AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 205 PM EDT TUE MAR 18 2008 .SYNOPSIS... HIGH PRESSURE WILL MOVE OFF THE SOUTHERN NEW ENGLAND COAST TODAY...AS A WARM FRONT SLOWLY APPROACHES FROM THE OHIO VALLEY AND THE MID ATLANTIC REGION WITH MIXED PRECIPITATION TONIGHT. A COMPLEX STORM SYSTEM OVER THE OHIO VALLEY AND GREAT LAKES REGION WILL BRING MORE UNSETTLED WEATHER TO THE REGION WEDNESDAY INTO THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... DESPITE THE DRY LOWER LEVELS AS SEEN IN THE SOUNDING HERE THIS MORNING...SURFACE TEMPERATURES HAVE YET TO REALLY RESPOND. THE MAIN CULPRIT IS INCREASING CLOUD COVER WHICH SEEMS TO BE TAKING A TOLL ON THE DIURNAL HEATING. LATEST GFS LAMP GUIDANCE IS STILL RUNNING A COUPLE DEGREES WARMER...BUT STILL COOLER THAN THE CURRENT GRIDS AND MOS GUIDANCE. THEREFORE...WILL DROP TEMPS SEVERAL DEGREES FOR THIS AFTERNOON. PRECIP CHANCES LOOK IN LINE WITH CURRENT RUC13 AND 12Z NAM12 AS PLENTY OF VIRGA EXPECTED GIVEN THE AFOREMENTIONED DRY LOW LEVELS. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... ONSET OF PRECIPITATION HINGES ON HOW PRECIPITATION CAN OVERCOME THE DEEP DRY LAYER. SOME CHANCES FOR RAIN AND SNOW IN CATSKILLS AND ADIRONDACKS BY SUNSET. LOW-LEVEL DEW POINTS WILL BE SLOW TO RISE...WITH AGEOSTROPHIC WINDS CONTINUING TO BE NORTHEAST..EVEN WITH THE ACTUAL SURFACE WINDS BEING SOUTHEAST. PRECIPITATION WILL START AS RAIN IN VALLEYS...BUT SNOW IN HIGHER ELEVATIONS. TEMPERATURES WILL FALL TOWARD WET BULB TEMPERATURES THROUGH THE NIGHT AS PRECIPITATION INTENSITY INCREASES...ESPECIALLY AFTER MIDNIGHT. SO...TEMPERATURES WILL FALL TO OR BELOW FREEZING IN MANY AREAS BY SUNRISE...EXCEPT FOR POU AREA. PRECIPITATION WILL BECOME SNOW AND SLEET OVER MOST AREAS THROUGH THE EVENING...AS THERMAL PROFILES SUGGEST AT OR BELOW FREEZING THOUGH MUCH OF THE NIGHT. THE BOUNDARY LAYER FREEZING LINE VERY SLOWLY INCHES THROUGH THE EASTERN CATSKILLS THROUGH THE SCHOHARIE VALLEY INTO THE CAPITAL DISTRICT BETWEEN MIDNIGHT AND SUNRISE. SOME MIXING WITH SLEET AND POCKETS OF FREEZING RAIN ARE POSSIBLE. WINTER WEATHER ADVISORY WILL BE ISSUED FOR ADIRONDACKS...WESTERN MOHAWK VALLEY...LAKE GEORGE AND SARATOGA REGIONS AND SOUTHERN VT. NO ADVISORY FOR THE CATSKILLS...CAPITAL DISTRICT OR BERKSHIRES...AS PRECIPITATION TRANSITION LOOKS TO BE SNOW AND SLEET TO RAIN...BUT INCLUDING CHANCES FOR FREEZING RAIN...FOR FLEXIBILITY TO REEVALUATE LATER TODAY...AS PRECIPITATION TRANSITIONS IN COMPLEX TERRAIN VERY MESSY. BUFKIT...PLUMES AND ENSEMBLE GUIDANCE NOT IN COMPLETE AGREEMENT ON PRECIPITATION TYPES...TRANSITIONS AND TIMING. WEDNESDAY...RAPID DEEP WARMING TAKES PLACE THROUGH THE MORNING AS STRONG SOUTHERLY LOW-LEVEL JET TRACKS INTO THE REGION. ALL PRECIPITATION WILL CHANGE TO RAIN BY MIDDAY...BUT DURING THE MORNING...AREAS OF THE WESTERN MOHAWK VALLEY...ADIRONDACKS...LAKE GEORGE AND SARATOGA REGIONS TO SOUTHERN VT COULD SEE ENOUGH FREEZING RAIN FOR SOME LIGHT ICE ACCUMULATIONS...MOSTLY IN HIGHER ELEVATIONS. HIGHS UPPER 30S COLDER AREAS TO 40S MOST EVERYWHERE ELSE. RAPID BOUNDARY LAYER COOLING WEDNESDAY EVENING...AND SOME SUGGESTION OF SOME ELEVATED INSTABILITY TRACKING THROUGH THE REGION...BUT NOT ENOUGH CONSENSUS TO ADD THUNDER TO FORECAST YET. ONCE COOLING TAKES PLACE...RAIN WILL TRANSITION TO SNOW SHOWER ACTIVITY. LOWS WILL RANGE FROM MID/UPPER 20S COOLER SPOTS TO 30S ELSEWHERE. THURSDAY...LINGERING CLOUDS AND LAKE EFFECT MOISTURE...SO SOME RAIN AND SNOW SHOWER ACTIVITY. WEST TO NORTHWEST WINDS WILL BE QUITE STRONG...AND MIGHT REQUIRE A WIND ADVISORY IN SOME PLACES. TEMPERATURES REACHING THE MID 30S IN COLDER AREAS TO LOWER/MID 40S ELSEWHERE. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... THU NT/FRI...COLD CYCLONIC FLOW WILL PROMOTE ABUNDANT CLOUDS AND SNOW SHOWERS ACROSS THE NORTH COUNTRY AND SOUTHERN VT...ESP THU NT. SOME LOCALLY HEAVIER SNOW BANDS ARE POSSIBLE ACROSS PORTIONS OF THE WESTERN ADIRONDACKS/MOHAWK VALLEY DURING THIS TIME PERIOD...WITH ADDITIONAL LIGHT TO MODERATE ACCUMS POSSIBLE. OTHERWISE...CONTINUED WINDY AND COLD...WITH MINS GENERALLY IN THE TEENS AND 20S...AND FRI MAXES MAINLY IN THE 20S AND 30S...EXCEPT SOME LOWER 40S WITHIN VALLEY LOCALES. FRI NT-SUN...WEAK CLIPPER SYSTEM APPEARS TO PASS WELL SOUTH OF REGION...IN RESPONSE TO DEEP CLOSED MID/UPPER LEVEL LOW OVER CANADIAN MARITIMES. 00Z/18 GFS ACTUALLY WRAPS MOISTURE AROUND WESTERN PERIPHERY OF MARITIME SYSTEM SOUTH...POSSIBLY KEEPING MORE CLOUDS...AND SNOW SHOWERS ACROSS THE NORTH COUNTRY INTO SUN. WILL NEED TO WATCH FOR THIS POSSIBILITY...AS ADDITIONAL OROGRAPHIC LIFT...AND ENHANCED LOW LEVEL MOISTURE FROM LAKES COULD PRODUCE ADDITIONAL SNOWFALL ACCUMS...PARTICULARLY ACROSS WEST FACING SLOPES OF THE DACKS AND GREENS. OTHERWISE...CONTINUED BLUSTERY...WITH MAXES MAINLY IN THE 20S TO LOWER 30S ACROSS THE HIGHER TERRAIN...AND 30S TO 40S WITHIN THE VALLEYS. HOWEVER...PERSISTENT BRISK WINDS WILL MAKE CONDITIONS FEEL EVEN COLDER. SUN NT-TUE...QUITE AN INTERESTING ARRAY OF MODEL SOLUTIONS DURING THIS TIME FRAME...ESP FOR MON-TUE. 00Z/18 GFS INDICATES A WEAK WAVE PASSING OFF TO OUR S...WHILE 00Z/18 ECMWF HINTS AT A POTENTIALLY ROBUST WINTER STORM FOR AT LEAST A PORTION OF OUR REGION. THE 00Z/18 MREF ENSEMBLE MEMBERS GENERALLY ARE MORE BENIGN...ALTHOUGH A FEW MEMBERS DO HINT AT A STORMIER PATTERN. FOR NOW...WILL INDICATE SLIGHT CHC POPS...HIGHEST TO THE S/E. HOWEVER...THIS PORTION OF FORECAST IS MUCH LOWER IN CONFIDENCE DUE TO THE CONSIDERABLE SPREAD OF MODEL SOLUTIONS. POTENTIAL BLOCKING PATTERN DEVELOPING ACROSS NE CANADA/N ATLANTIC USUALLY FORBODES A RELATIVELY STORMY PATTERN ACROSS EASTERN NOAM...ALTHOUGH STRONG BLOCKING CAN ALSO SUPPRESS THE STORM TRACK TOO FAR S OF OUR REGION. EITHER WAY...WILL CONTINUE TO INDICATE COLDER THAN SEASONAL TEMPS...WITH MAXES IN THE 20S ACROSS HIGHER ELEVATIONS...AND 30S TO LOWER 40S ACROSS THE VALLEYS. HOWEVER...SHOULD THE GFS PROVE CORRECT...EVEN COLDER MAXES ARE POSSIBLE...ALONG WITH OVERNIGHT MINS THAT COULD DIP CLOSE TO...OR EVEN SLIGHTLY BELOW ZERO ACROSS PORTIONS OF THE NORTH COUNTRY/SOUTHERN VT BY TUE AM. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... VFR CONDITIONS WILL CONTINUE THROUGH AT LEAST 00Z/WED...WITH LOWERING CIGS AS OVC050 MOVE IN FROM THE WEST. LIGHT SHOWERS WILL MOVE INTO KGFL/KALB AROUND 23Z/00Z. SOMEWHAT STEADIER PRECIP WILL DEVELOP AT 01Z KPOU AND 02Z KGFL/KALB. THIS PRECIP WILL BE ACCOMPANIED BY MVFR/IFR VSBYS AND CIGS. CONDITIONS WILL CONTINUE TO DETERIORATE WITH THE WORST CONDITIONS AS IFR AFTER SUNRISE 13Z/14Z AT ALL TERMINALS. AS FOR PRECIP AND P-TYPE...PRECIP WILL START AS A RAIN/SNOW MIX. THEREAFTER...PRECIP SHOULD BECOME A RAIN/SLEET MIX...EXCEPT AT KGFL WHERE A MIX OF FREEZING RAIN AND SLEET IS MORE LIKELY. PRECIP SHOULD BECOME ALL RAIN BY 12Z/WED...EXCEPT AT KGFL WHERE FREEZING RAIN IS EXPECTED TO LINGER. WINDS STRONGEST AT KALB AND REMAIN SO THROUGHOUT THE NEXT 24HRS. KGFL AND KPOU WIND SPEEDS INCREASING IN THE EVENING...STAYING BETWN 4-8KTS. OUTLOOK... WED-THU AM...MVFR/IFR. RAIN AND OR MIXED PCPN LIKELY. THU PM...VFR/MVFR. SCT -SHRA/-SHSN...STRONG WINDS POSSIBLE. FRI THRU SUN...VFR...NO SIG WX. && .FIRE WEATHER... HIGH PRESSURE WILL SLIDE EAST OFF THE NEW ENGLAND COAST TODAY. A COMPLEX LOW PRESSURE SYSTEM WILL LIFT NORTHEAST INTO THE OHIO VALLEY TONIGHT PUSHING A WARM FRONT IN OUR DIRECTION. THE LOW PRESSURE SYSTEM IS THEN EXPECTED TO TRACK EAST ACROSS PENNSYLVANIA ON WEDNESDAY AND THEN LIFT NORTHEAST ACROSS SOUTHEAST NEW YORK AND SOUTHERN NEW ENGLAND WEDNESDAY NIGHT...BRINGING UNSETTLED WEATHER TO THE REGION TUESDAY NIGHT INTO THURSDAY. THREE QUARTERS OF THE FA REMAINS SNOW COVERED WITH THE EASTERN MOHAWK VALLEY...THE HUDSON VALLEY SOUTH OF SARATOGA SPRINGS...PORTIONS OF THE SOUTHERN BERKSHIRES AND THE LITCHFIELD HILLS BEING THE ONLY AREAS WITHOUT SNOW COVER. RELATIVE HUMIDITY LEVELS WILL FALL INTO THE 20-30 PERCENT RANGE ACROSS THE MID HUDSON VALLEY...LITCHFIELD HILLS AND WESTERN MA...TO 40-50 PERCENT ACROSS THE WESTERN MOHAWK VALLEY AND ADIRONDACKS THIS AFTERNOON...RECOVERING TO 85-95 PERCENT TONIGHT. RH LEVELS WILL ONLY FALL SLIGHTLY FOR WED AFTERNOON...INTO THE 70-80 PERCENT RANGE. NO PRECIPITATION IS EXPECTED UNTIL THIS EVENING...WHEN A MIX OF LIGHT RAIN/SNOW/SLEET AND FREEZING RAIN IS EXPECTED...WITH A TRANSITION TO MOSTLY RAIN ESPECIALLY ACROSS SOUTHERN PORTIONS OF THE FA ON WEDNESDAY. HAINES INDICES WILL REACH 4 TO 5 ACROSS MOST AREAS THIS AFTERNOON...BUT WILL GENERALLY REMAIN AROUND 2 FOR WED. TRANSPORT WINDS WILL INITIALLY BE LIGHT AND VARIABLE THIS MORNING...BEFORE BECOMING SOUTH TO SOUTHEAST AND INCREASING TO 15 TO 25 MPH THIS AFTERNOON AND TONIGHT...WITH SOUTH WINDS INCREASING TO 30-40 MPH ON WED. && .HYDROLOGY... ANOTHER SIGNIFICANT PRECIPITATION EVENT IS EXPECTED TONIGHT INTO WED NIGHT. THE EVENT SHOULD CONSIST OF 2 MAXIMA...THE FIRST OCCURRING AHEAD OF A WARM FRONT FOR TUE NT/EARLY WED...WHICH SHOULD INVOLVE SOME FROZEN/MIXED P-TYPE. THE MORE SIGNIFICANT PRECIPITATION...MAINLY IN THE FORM OF RAIN...IS EXPECTED WED AFTERNOON THROUGH WED NT. CURRENT FORECASTS INDICATE THE POTENTIAL FOR 1-2 INCHES OF TOTAL QPF BY THU MORNING...ALTHOUGH CONFIDENCE IS STILL SOMEWHAT LOW ON THE EXPECT PLACEMENT OF THE MAXIMA. SINCE RIVERS/STREAMS/CREEKS ARE ALREADY RUNNING ANOMALOUSLY HIGH DUE TO THE ABUNDANCE OF ANTECEDENT RAINFALL...FLOODING CONCERNS WILL EXIST. THE MAIN AREAS OF CONCERN AT THIS POINT ARE FROM THE SOUTHEAST CATSKILLS EAST TO THE HOUSATONIC BASIN SOUTH OF MASSACHUSETTS. AT THIS POINT WILL CONTINUE TO HIGHLIGHT POTENTIAL OF FLOODING IN THE HWOALY. ALTHOUGH DEEP SNOWPACK CONTINUES ACROSS THE ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS OF VT...SNOWMELT POTENTIAL SEEMS LIMITED GIVEN TEMPS EXPECTED TO REMAIN BELOW 40 DEGREES THROUGH MUCH OF THIS EVENT...ALONG WITH EXPECTATION FOR TEMPS TO FALL BACK WELL BELOW FREEZING BY THU MORNING. THUS...IN ADDITION TO WATCHING FOR HEAVY RAIN POTENTIAL...THE TEMPERATURES WILL PLAY A CRITICAL ROLE AS WELL...AS ANY GREATER EROSION OF THE COLDER AIR AHEAD OF THE STORM SYSTEM WOULD RESULT IN A GREATER FLOOD THREAT ACROSS THESE AFOREMENTIONED SNOWPACKED AREAS. PLEASE REFER TO OUR ADVANCED HYDROLOGIC PREDICTION SERIES /AHPS/ PAGES ON THE WEB FOR DETAILS AND UPDATES ON THE RIVERS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO 11 AM EDT WEDNESDAY FOR NYZ032-033-038>043-047-048-082>084. MA...NONE. VT...WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO 11 AM EDT WEDNESDAY FOR VTZ013>015. && $$ NEAR TERM...BGM AVIATION...KGS FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 946 PM EDT MON MAR 17 2008 .SYNOPSIS... HIGH PRESSURE OVER THE AREA EARLY TONIGHT WILL MOVE OFFSHORE OVERNIGHT. LOW PRESSURE WILL PUSH IN FROM THE WEST WITH THE ASSOCIATED WARM FRONT PASSING NORTH OF THE REGION WEDNESDAY AFTERNOON, AND THE COLD FRONT MOVING OFFSHORE THURSDAY MORNING. HIGH PRESSURE WILL SPREAD OVER THE REGION UNTIL FRIDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... HIGH CLOUDS WERE ADVANCING INTO THE AREA AT EARLY EVENING, AS THEY WERE SPILLING OVER THE UPPER RIDGE AXIS WHICH WAS JUST WEST OF OUR AREA EARLY TONIGHT, AND WILL MOVE OVER OUR AREA OVERNIGHT. SO, THE PREVIOUS THEME OF HIGH CLOUDS THICKENING AND LOWERING WILL BE CONTINUED OVERNIGHT AS UPWARD VERTICAL MOTION GETS UNDERWAY IN ADVANCE OF THE NEXT UPPER TROUGH. WITH THICKENING CLOUDS, SOME UPWARD ADJUSTMENTS WERE MADE TO MINIMUM TEMPERATURES BY A DEGREE OR TWO. ALSO, RUC WINDS WERE USED TO START THE NIGHT OFF, AS THEY WERE NORTHERLY FOR MOST PLACES, EXCEPT WEST OVER OUR SOUTHERN ZONES. WINDS SHOULD BE PRETTY LIGHT OVERNIGHT. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... THE NORTHERN BRANCH WILL IMPINGE ON THE SOUTHERN BRANCHES ATTEMPT TO MOVE NORTH AND KEEP THE STREAM OF MOISTURE HEADED IN OUR DIRECTION. BY TUESDAY NIGHT...THE QPF MAX THROUGH THE MISSOURI AND OHIO VALLEY WILL BE SHEARED OFF TO THE EAST AND WEAKEN AS THE COLD FRONT...AIDED BY THE NORTHERN PUSH...BEGINS A MOVE TOWARD THE EAST ON WEDNESDAY. HEAVIEST QPF STILL ACROSS OUR NORTHERN ZONES BY WEDNESDAY AFTERNOON. LOWS FOR TUESDAY NIGHT WILL BE WARM AND HIGHS ON WEDNESDAY VERY MILD WITH MID TO UPPER 60S DOWN SOUTH. FOR WEDNESDAY NIGHT...THE SURFACE LOW WILL BE TRACKING ACROSS CENTRAL PENNSYLVANIA HEADED INTO SOUTHEAST NEW ENGLAND. WE`RE NEAR THE TRIPLE POINT ACROSS OUR SOUTHERN ZONES SO THINK I`LL JOIN MY COLLEAGUES FROM CTP AND AKQ AND INTRO A CHANCE OF A TSTM. THE COLD FRONT WILL BE MOVING OFFSHORE LATE WEDNESDAY AND ANY LEFT OVER SHOWERS MAY MIX WITH WET SNOW BEFORE ENDING UP NORTH. INSPITE OF THE COLD AIR ADVECTION, TEMPERATURES ON THURSDAY IN THE LOWER 40S TO UPPER 50S AND OVERNIGHT LOWS THURSDAY 19 TO 33. && .LONG TERM /THURSDAY THROUGH MONDAY/... WITH THE STRONG RIDGE OFFSHORE...THE SHORT WAVE OFFSHORE THURSDAY...THE FLOW RETURNS TO THE HI INDEX PACIFIC FLOW WE`VE SEEN SO OFTEN THIS YEAR. EMBEDDED WITHIN THE FLOW IS MOISTURE FROM THE PACIFIC THAT IS GOING TO REACH THE WESTERN PARTS OF OUR REGION BY FRIDAY EVENING. SYSTEM HAS ENOUGH DYNAMICS ESPECIALLY BELOW 80H TO BRING A .25 TO .31 QPF EVENING. MEANWHILE, THE TEMPERATURES ARE COLD AND WE CAN EXPECT TO SEE SOME LIGHT ACCUMULATING SNOW BEFORE THIS EVENT ENDS BY SATURDAY EVENING. SOME AREAS WILL HAVE A MIX OF RAIN AND SNOW SHOWERS. THE PRECIPITATION PUSHES SOUTH TO THE DELMARVA BY SATURDAY EVENING. HIGH PRESSURE WILL BUILD SOUTH FROM CENTRAL CANADA SATURDAY NIGHT...SUNDAY AND MONDAY WHILE THE UPPER CYCLONE SPINS AROUND WITH THE CENTER OVER JAMES BAY. OUR CHANGEABLE UPPER AIR PATTER WILL CONTINUE UNSETTLED FOR THE FOLLOWING WEEK. TEMPERATURES THROUGH THIS PERIOD WILL BE SLIGHTLY BELOW THE NORM. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... HIGH PRESSURE FROM SOUTHEASTERN CANADA TO VIRGINIA WILL CONTINUE TO SLIDE EASTWARD OVERNIGHT. PLENTY OF DRY AIR IS IN PLACE IN ASSOCIATION WITH THIS SURFACE HIGH, HOWEVER CIRRUS WAS BUILDING EASTWARD OVER THE AREA. CIRRUS CEILINGS WILL THICKEN AND LOWER OVERNIGHT AS A WARM FRONT ORGANIZES TO OUR SOUTHWEST, HOWEVER CONDITIONS WILL REMAIN VFR. AS THE AFOREMENTIONED WARM FRONT BECOMES BETTER DEFINED ON TUESDAY, CEILINGS WILL LOWER AND THIS SHOULD BECOME ENHANCED SOME BY A DEVELOPING SOUTHEASTERLY FLOW. THERE IS SOME UNCERTAINTY REGARDING HOW QUICKLY EAST SOME PRECIPITATION GETS ON TUESDAY, THEREFORE WE DID NOT HIT THIS REAL HARD AT THIS TIME. FOR NOW, WE INDICATED SOME LIGHT SHOWER POTENTIAL FOR KABE AND KRDG TOWARD 18Z TUESDAY, WITH A VICINITY SHOWER INDICATED ELSEWEHRE IN THE AFTERNOON, WITH A TEMPO GROUP FOR LOWER MARGINAL VFR CONDITIONS TOWARD DARK TUESDAY. IF THE PRECIPITATION DOES ARRIVE EARLY ENOUGH, THERE COULD BE ENOUGH EVAPORATIONAL COOLING TO PRODUCE SOME SNOW/ICE PELLETS AT KRDG AND KABE. THIS WAS NOT INCLUDED DUE TO THE UNCERTAINTY. LIGHT EASTERLY WINDS WILL INCREASE DURING THE MORNING AND SHIFT TO THE SOUTHEAST. OUTLOOK... A STORM SYSTEM TRACKS TO OUR WEST LATER TUESDAY AND WEDNESDAY, EVENTUALLY SWEEPING A COLD FRONT ACROSS ALL TERMINALS LATER WEDNESDAY NIGHT. THIS SYSTEM APPEARS TO PULL UP A FAIR AMOUNT OF MOISTURE ACROSS OUR AREA. THIS WILL PRODUCE DETERIORATING CEILINGS AND VISIBILITIES ESPECIALLY LATER TUESDAY THROUGH MOST OF WEDNESDAY. THERE MAY BE LOW-LEVEL WIND SHEAR MAINLY LATER TUESDAY INTO WEDNESDAY. WHILE NOT A HIGH PROBABILITY AT THIS TIME, SOME THUNDER IS POSSIBLE LATER WEDNESDAY. HIGH PRESSURE THEN BUILDS IN BRIEFLY FOR THURSDAY INTO FRIDAY, HOWEVER A WEAK AND QUICK MOVING STORM SYSTEM MAY CRUISE JUST TO OUR SOUTH FRIDAY NIGHT INTO SATURDAY. && .MARINE... AS THE SURFACE HIGH BUILDS OVER THE AREA WATERS, THE WINDS AND SEAS WILL CONTINUE TO DIMINISH. HOWEVER, WITH 6 FOOT SEAS AT BUOY 44009 AT 01Z, DESPITE BEING A LONG PERIOD AT 11 SECONDS, THE SMALL CRAFT ADVISORY WILL BE EXTENDED UNTIL 06Z OVER OUR SOUTHERN OCEAN WATERS TO MESH WITH OUR SOUTHERN NEIGHBOR. SEAS ARE THEN EXPECTED TO BE BELOW 5 FEET FOR AWHILE LATE TONIGHT AND MOST OF TUESDAY, BUT THEN A STRENGTHENING SOUTHEASTERLY FLOW WILL BUILD SEAS ONCE AGAIN TUESDAY NIGHT AND WEDNESDAY. A WARM FRONT WILL LIFT NORTHWARD TUESDAY NIGHT AND WEDNESDAY. AS THIS OCCURS, WINDS ABOVE THE SURFACE ARE FORECAST TO INCREASE SUBSTANTIALLY. THIS IS A CASE THOUGH ONCE AGAIN WHERE MILDER AIR WILL BE ARRIVING OVER THE COOLER WATER. THIS SCENARIO DOES NOT FAVOR THE STRONGER WINDS REACHING THE SURFACE. HOWEVER THERE WILL BE ENOUGH OF A SOUTHERLY FLOW TO HELP BUILD SEAS BACK UP BEYOND 5 FEET. THEREFORE WE WILL PROBABLY NEED A SMALL CRAFT ADVISORY ONCE AGAIN STARTING TUESDAY NIGHT, AT LEAST FOR THE OCEAN ZONES. THE SOUTHEASTERLY FLOW WILL FUNNEL UP DELAWARE BAY SOME AS WELL LATER TUESDAY INTO WEDNESDAY. THE SOUTHERLY WINDS ARE EXPECTED TO INCREASE SOME MORE ON WEDNESDAY AS A STORM SYSTEM MOVES TO OUR WEST. EVEN THOUGH WINDS ABOVE THE SURFACE WILL CONTINUE TO STRENGTHEN, THIS WILL NOT COMPLETELY REACH THE SURFACE AS FORECAST SOUNDINGS KEEP A LOW-LEVEL INVERSION IN PLACE THROUGH WEDNESDAY. AS A COLD FRONT THOUGH MOVES THROUGH LATER WEDNESDAY NIGHT INTO THURSDAY MORNING, WE BEGIN TO LOSE THE LOW-LEVEL INVERSION. ONCE THE WINDS SHIFT TO THE WEST AND COLDER AIR ARRIVES ALOFT, THIS WILL ALLOW VERTICAL MIXING TO BE MAXIMIZED. THE WIND FIELD ALOFT IS SUCH THAT GALE FORCE CONDITIONS WILL BE QUITE POSSIBLE ON THURSDAY. THE GUSTY WINDS WILL PROBABLY HOLD ON FOR AWHILE ON FRIDAY AS HIGH PRESSURE SLIDES TO OUR SOUTH. A WEAK AND QUICK MOVING SYSTEM MAY THEN AFFECT OUR WEATHER LATE FRIDAY INTO SATURDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR ANZ452>455. && $$ SYNOPSIS.../ EBERWINE NEAR TERM.../ EBERWINE SHORT TERM...EBERWINE LONG TERM...DELISI/EBERWINE AVIATION.../ GORSE MARINE.../ GORSE de AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TALLAHASSEE FL 645 AM EDT TUE MAR 18 2008 ...UPDATED TO DISCUSS HIGH SURF IMPACTS... .SYNOPSIS... 06Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING AN ACTIVE AND AMPLIFIED UPPER LEVEL PATTERN ACROSS NORTH AMERICA THIS MORNING. FROM EAST TO WEST WE SEE LARGE AND DOMINANT RIDGING EXTENDING NORTHWARD FROM THE EASTERN GULF OF MEXICO ALONG THE SPINE OF THE APPALACHIANS INTO SOUTHERN ONTARIO AND QUEBEC. FURTHER UPSTREAM WE FIND TROUGHING FROM THE SOUTHERN PRAIRIES OF CANADA DOWN INTO THE PLAINS STATES AND NORTHERN MEXICO. THE SOUTHERN PORTIONS OF THE TROUGH IS PINCHING OFF FROM THE NORTHERN STREAM ENERGY WITH A CLOSED CONTOUR FROM NORTHERN MEXICO INTO NEW MEXICO AND WESTERN TEXAS. AT THE SURFACE...HIGH PRESSURE CENTERED WELL TO OUR NORTHEAST ACROSS THE MID-ATLANTIC STATES CONTINUES TO PROVIDE FAIR WEATHER WITH A STEADY SOUTHEAST FLOW ACROSS THE FORECAST AREA. WARM NIGHT ONGOING WITH TEMPERATURES SLOWLY FALLING THROUGH THE UPPER 50S AND 60S. WELL OFF TO THE WEST WE SEE A COMPLEX SURFACE LOW/FRONTAL SYSTEM FROM SOUTHERN TEXAS NORTHEAST INTO THE MIDDLE MISSISSIPPI VALLEY ALONG THE LEADING EDGE OF THE MID/UPPER LEVEL TROUGH. NUMEROUS SHOWERS/STORMS ARE CURRENTLY ONGOING ACROSS THIS AREA. THIS AREA OF INCLEMENT WEATHER WILL REMAIN TO OUR WEST THOUGH TODAY BUT WILL BE MAKING SOME EASTWARD PROGRESS AND WILL EVENTUALLY COMPLICATE OUR WEATHER INTO WEDNESDAY/WEDNESDAY NIGHT. && .SHORT TERM...(TODAY-THURSDAY) STRONG MID/UPPER LEVEL RIDING WILL KEEP OUR WEATHER FAIR AND CONTINUED WARM TODAY. A FAIRLY TIGHT GRADIENT BETWEEN SURFACE HIGH PRESSURE WELL TO OUR NORTHEAST AND EVOLVING LOW PRESSURE WEST OF THE LOWER MISSISSIPPI VALLEY WILL CONTINUE A STEADY AND INCREASINGLY MOIST SOUTHEAST FLOW INTO THE REGION. ANTICIPATING FILTERED SUNSHINE INTO THE EARLY EVENING THROUGH PERIODS OF CIRRUS AHEAD OF THE APPROACHING SYSTEM TO OUR WEST. HIGH TEMPERATURES QUITE PLEASANT FOR MID MARCH WITH MIDDLE AND UPPER 70S COMMON. ONCE AGAIN A FEW WARMER LOCATIONS FROM KTLH TO KVLD AND KCTY ARE LIKELY TO APPROACH THE 80 DEGREE MARK. LOCATIONS ALONG THE IMMEDIATE COAST WEST OF JEFFERSON COUNTY ARE LIKELY TO SEE TEMPS A FEW DEGREES LOWER WITH FLOW OFF THE RELATIVELY COOLER SHELF WATERS. POTENT UPPER LEVEL SYSTEM EJECTS NORTHEAST INTO THE MIDDLE AND LOWER MISSISSIPPI VALLEY TONIGHT. ASSOCIATED SURFACE LOW PRESSURE WILL ALSO EJECT NORTHEAST INTO THE TN/OH VALLEYS BY SUNRISE WEDNESDAY. TRAILING COLD FRONT BY THE END OF TONIGHT WILL REACH A POSITION FROM NEAR NASHVILLE TN SOUTHWEST INTO THE LOWER MISSISSIPPI VALLEY. LINE OF SHOWERS AND THUNDERSTORMS WILL LIKELY BE PROGRESSING EASTWARD IN ADVANCE OF THIS FRONT THROUGH THE NIGHT. AT THIS TIME WOULD APPEAR THAT THE MAIN ROUND OF SHOWERS AND STORMS WILL REMAIN TO OUR WEST THROUGH THE NIGHT ALTHOUGH A FEW MORE ISOLATED SHOWERS/TSTORMS ARE POSSIBLE VERY LATE ACROSS THE EASTERN FL PANHANDLE INTO SOUTHEASTERN ALABAMA. WOULD EXPECT AN INCREASE IN CLOUDS FROM WEST TO EAST THROUGH THE NIGHT WITH A BREEZY SOUTHERLY WIND KEEPING LOW TEMPERATURES ON THE WARM SIDE. CURRENT GRIDS WILL SHOW LOWS AROUND 60 OR PERHAPS A FEW DEGREES WARMER INLAND AND MIDDLE AND UPPER 60S ALONG THE COAST. WITH THE STRONG SOUTHERLY FLOW HIGH SURF AND ABOVE NORMAL TIDES ARE BECOMING MORE LIKELY TONIGHT INTO WEDNESDAY. CURRENT FORECAST SHOWS TIDES RUNNING ABOUT ONE FOOT ABOVE NORMAL BY LATER TODAY INTO WEDNESDAY. THESE HIGHER THAN NORMAL TIDES COMBINED WITH POSSIBLE LARGE SURF MAY RESULT IN SOME MINOR BEACH EROSION AND EVEN SOME POSSIBLE MINOR FLOODING ALONG VULNERABLE ROADWAYS TONIGHT INTO WEDNESDAY...ESPECIALLY AT THE TIMES OF HIGH TIDE. A HIGH SURF ADVISORY MAY BE REQUIRED LATER TODAY. UPPER LEVEL SHORTWAVE ENERGY AND ASSOCIATED COLD FRONT WILL CONTINUE TO APPROACH THE AREA WEDNESDAY. COLD FRONT IS LIKELY TO REACH OUR WESTERN ZONES BY LATE IN THE DAY WITH A ROUND OF SHOWERS AND THUNDERSTORMS SPREADING EASTWARD IN ADVANCE. BEST ESTIMATE AT THE TIMING OF THE STEADIER SHOWERS/TSTORMS WILL BE FROM MID MORNING TO LATE AFTERNOON OVER OUR WESTERN ZONES AND DURING THE AFTERNOON AND EVENING HOURS OVER OUR EASTERN ZONES. COLD FRONT SHOULD EXIT THE SOUTHEAST FL BIG BEND AFTER MIDNIGHT WITH ANY LINGERING SHOWERS/STORMS COMING TO AN END DURING THE LATE NIGHT HOURS. ZONAL MID/UPPER LEVEL FLOW AND SURFACE HIGH PRESSURE WILL ESTABLISH BEHIND THE FRONT DURING THURSDAY WITH FAIR WEATHER AND SEASONABLE TEMPERATURES FOR THE END OF THE WORK WEEK. A QUICK LOOK AT ANY SEVERE THREAT WITH THE FRONTAL PASSAGE WEDNESDAY AND WEDNESDAY NIGHT. FAMILIAR SETUP TO THIS EVENT WITH THE USUAL BATTLE BETWEEN VERY FAVORABLE LOW LEVEL AND DEEP LAYER SHEAR PROFILES AND UNFAVORABLE INSTABILITY. FIRST WE WILL LOOK AT THE FAVORABLE SIDE...0-6KM DEEP LAYER BULK SHEAR IS QUITE IMPRESSIVE WITH MODEL CONSENSUS BETWEEN 55 AND 60 KTS AHEAD OF THE FRONT AND CERTAINLY ENOUGH TO MAINTAIN ENHANCED UPDRAFTS. IMPRESSIVE LOW LEVEL JET ALSO EXPECTED WITH GFS/SREF SHOWING WIDE SWATH OF 50-60 KNOTS AT 850MB. SUFFICIENT WIND PROFILES SHOULD BE IN PLACE...HOWEVER AS MENTIONED ABOVE THE INSTABILITY IS MARGINAL AT BEST. BUFKIT PROFILES ARE SHOWING FAIRLY WEAK LAPSE RATES IN THE MID LEVELS WITH SURFACE BASED INSTABILITY PEAKING IN THE 200-300 J/KG RANGE AND MU CAPES ONLY AROUND 400 J/KG. TAKING ALL THIS IN MIND...DO NOT EXPECT A WIDESPREAD SEVERE WX EVENT ON WEDNESDAY... HOWEVER WITH THE VERY STRONG SHEAR PROFILES...CAN NOT RULE OUT A FEW ISOLATED STRONG TO SEVERE CELLS/BOWING SEGMENTS IN LINE WITH THE LATEST FORECAST FROM THE STORM PREDICTION CENTER WHICH CONTINUES TO OUTLOOK OUR AREA FOR A SLIGHT RISK OF SEVERE WEATHER WITH THIS EVENT. MAIN THREATS WILL BE DAMAGING STRAIGHT LINE WINDS AND THE POSSIBILITY OF ISOLATED TORNADOES. DUE TO THE WEAK FORECAST LAPSE RATES AND INSTABILITY... WOULD APPEAR THE HAIL THREAT WILL BE MARGINAL AT BEST. WILL CONTINUE TO MONITOR THE SITUATION CLOSELY AS ANY TREND TOWARD HIGHER INSTABILITY WILL INCREASE THE OVERALL THREAT. && .LONG TERM... FAIR WEATHER WILL DOMINATE LONG TERM. STRONG ZONAL FLOW ALOFT WITH HIGH PRESSURE AT SURFACE WILL CONTINUE OVER FORECAST AREA WITH PERSISTENT DRY CONDITIONS THROUGH SATURDAY. ON SUNDAY...WEAK TROUGHING MOVING EWD INTO SE CONUS SHUNTED HIGH TOWARDS WRN ATLC. SHORTWAVE SYSTEM MOVES ACROSS THE SOUTHEAST STATES DRAGGING A WEAK COLD FRONT ACROSS CWA. 00Z GUIDANCE EVEN LESS IMPRESSIVE WITH SYSTEM THAN PREVIOUS RUN. WILL INCLUDE SLIGHT CHANCE POPS...MAINLY W HALF CWA IN PACKAGE. IN ITS WAKE...STRONG HIGH BUILDS SOUTH INTO REGION AND DRY CONDITIONS RETURN FOR EARLY WORK WEEK. IN WAKE OF INITIAL FRONT THAT EXITS CWA ON WED...MAX TEMPS REMAIN SEASONABLE EXCEPT FOR MODESTLY BELOW CLIMO ON SUN UNDER INFLUENCE OF CLOUDS ASSOCIATED WITH SECOND FRONT. MINS BEGIN BELOW CLIMO IN WAKE OF INITIAL FRONT AND THEN RISE TO NEAR CLIMO NEXT FEW NIGHTS BEFORE AGAIN DROPPING BELOW CLIMO SUN AND MON NIGHT IN WAKE OF SECOND FRONT. && .AVIATION... UNDER INCREASINGLY LOW LEVEL MOISTURE GENERATED BY WINDS VEERING TO STRONG EAST-SOUTHEAST FLOW....MVFR CIGS EXPECTED DURING PRE-DAWN HOURS THE REGION. THIS IS SUPPORTED BY BOTH THE NAM AND GFS AS WELL AS THE SREF PROBS. MAY ALSO SEE SOME LIGHT BR AT AREA TERMINALS STRENGTH OF BOUNDARY LAYER WINDS SHOULD KEEP CONDS ABOVE IFR. AFTER DAYBREAK...SHOULD SEE MVFR CIGS LIFT AND GRADUALLY SCATTER BY 15Z WITH BREEZY VFR CONDITIONS PREVAILING THROUGH THE REMAINDER OF THE TAF CYCLE. CLOUD DECKS WILL BEGIN TO LOWER FROM W-E AHEAD OF NEXT WEATHER MAKER AFTER MIDNIGHT BUT REMAIN ABOVE VFR THRU 06Z. && .MARINE... TIGHT GRADIENT BETWEEN HIGH PRESSURE TO OUR NORTHEAST AND LOW PRESSURE TO OUR WEST WILL KEEP WINDS ELEVATED OVER THE MARINE AREA TODAY. THESE WINDS AND SEAS ARE EXPECTED TO RISE TO ADVISORY LEVELS DURING THE DAY...ESPECIALLY ACROSS THE WESTERN LEGS. AS A COLD FRONT BEGINS TO APPROACH FROM THE WEST TONIGHT...ADVISORY LEVEL WINDS AND SEAS WILL BE MAINTAINED AND EXPAND EASTWARD TO COVER ALL OF THE FORECAST WATERS. COLD FRONT WILL CROSS THE WATERS LATER WEDNESDAY AND WEDNESDAY NIGHT WITH A LIKELY ROUND OF SHOWERS AND THUNDERSTORMS. ELEVATED WINDS AND SEAS WILL LINGER EVEN BEHIND THE FRONT INTO THE DAY ON THURSDAY BEFORE BEGINNING TO SUBSIDE LATE IN THE WEEK AS HIGH PRESSURE BUILDS TO THE NORTH. && .FIRE WEATHER... LOW LEVEL MOISTURE WILL BE ON THE INCREASE DURING THE NEXT 36 HOURS WITH RH VALUES REMAINING ABOVE CRITICAL LEVELS. CRITICAL FIRE WEATHER CONDITIONS ARE ANTICIPATED TO RETURN TO PORTIONS OF THE AREA BY THURSDAY AFTERNOON BEHIND A COLD FRONT LATER WEDNESDAY AND WEDNESDAY NIGHT. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 79 61 76 51 72 / 0 05 70 60 0 PANAMA CITY 78 65 75 51 71 / 0 20 70 40 0 DOTHAN 79 61 73 45 73 / 0 20 70 40 0 ALBANY 78 61 76 48 74 / 0 10 70 50 0 VALDOSTA 78 59 81 52 74 / 0 05 50 70 05 CROSS CITY 80 60 81 57 73 / 0 0 30 60 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...FIRE WEATHER WATCH IN EFFECT FOR THURSDAY AFTERNOON FOR SOUTHEAST ALABAMA. GA...FIRE WEATHER WATCH IN EFFECT FOR PORTIONS OF SOUTHWEST GEORGIA THURSDAY AFTERNOON. FL...FIRE WEATHER WATCH IN EFFECT FOR THURSDAY AFTERNOON FOR ALL OF THE EASTERN FLORIDA PANHANDLE AND FLORIDA BIG BEND. GM...SMALL CRAFT ADVISORY IN EFFECT THROUGH WEDNESDAY EVENING FOR THE FOLLOWING ZONES: COASTAL WATERS FROM OCHLOCKONEE RIVER TO APALACHICOLA FL OUT TO 20 NM...COASTAL WATERS FROM APALACHICOLA TO DESTIN FL OUT 20 NM...WATERS FROM SUWANNEE RIVER TO APALACHICOLA FL FROM 20 TO 60 NM...WATERS FROM APALACHICOLA TO DESTIN FL FROM 20 TO 60 NM. && $$ AVIATION/FIRE WX/LONG TERM...BLOCK PUBLIC/MARINE...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 330 AM EDT TUE MAR 18 2008 .SYNOPSIS... 06Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING AN ACTIVE AND AMPLIFIED UPPER LEVEL PATTERN ACROSS NORTH AMERICA THIS MORNING. FROM EAST TO WEST WE SEE LARGE AND DOMINANT RIDGING EXTENDING NORTHWARD FROM THE EASTERN GULF OF MEXICO ALONG THE SPINE OF THE APPALACHIANS INTO SOUTHERN ONTARIO AND QUEBEC. FURTHER UPSTREAM WE FIND TROUGHING FROM THE SOUTHERN PRAIRIES OF CANADA DOWN INTO THE PLAINS STATES AND NORTHERN MEXICO. THE SOUTHERN PORTIONS OF THE TROUGH IS PINCHING OFF FROM THE NORTHERN STREAM ENERGY WITH A CLOSED CONTOUR FROM NORTHERN MEXICO INTO NEW MEXICO AND WESTERN TEXAS. AT THE SURFACE...HIGH PRESSURE CENTERED WELL TO OUR NORTHEAST ACROSS THE MID-ATLANTIC STATES CONTINUES TO PROVIDE FAIR WEATHER WITH A STEADY SOUTHEAST FLOW ACROSS THE FORECAST AREA. WARM NIGHT ONGOING WITH TEMPERATURES SLOWLY FALLING THROUGH THE UPPER 50S AND 60S. WELL OFF TO THE WEST WE SEE A COMPLEX SURFACE LOW/FRONTAL SYSTEM FROM SOUTHERN TEXAS NORTHEAST INTO THE MIDDLE MISSISSIPPI VALLEY ALONG THE LEADING EDGE OF THE MID/UPPER LEVEL TROUGH. NUMEROUS SHOWERS/STORMS ARE CURRENTLY ONGOING ACROSS THIS AREA. THIS AREA OF INCLEMENT WEATHER WILL REMAIN TO OUR WEST THOUGH TODAY BUT WILL BE MAKING SOME EASTWARD PROGRESS AND WILL EVENTUALLY COMPLICATE OUR WEATHER INTO WEDNESDAY/WEDNESDAY NIGHT. && .SHORT TERM...(TODAY-THURSDAY) STRONG MID/UPPER LEVEL RIDING WILL KEEP OUR WEATHER FAIR AND CONTINUED WARM TODAY. A FAIRLY TIGHT GRADIENT BETWEEN SURFACE HIGH PRESSURE WELL TO OUR NORTHEAST AND EVOLVING LOW PRESSURE WEST OF THE LOWER MISSISSIPPI VALLEY WILL CONTINUE A STEADY AND INCREASINGLY MOIST SOUTHEAST FLOW INTO THE REGION. ANTICIPATING FILTERED SUNSHINE INTO THE EARLY EVENING THROUGH PERIODS OF CIRRUS AHEAD OF THE APPROACHING SYSTEM TO OUR WEST. HIGH TEMPERATURES QUITE PLEASANT FOR MID MARCH WITH MIDDLE AND UPPER 70S COMMON. ONCE AGAIN A FEW WARMER LOCATIONS FROM KTLH TO KVLD AND KCTY ARE LIKELY TO APPROACH THE 80 DEGREE MARK. LOCATIONS ALONG THE IMMEDIATE COAST WEST OF JEFFERSON COUNTY ARE LIKELY TO SEE TEMPS A FEW DEGREES LOWER WITH FLOW OFF THE RELATIVELY COOLER SHELF WATERS. POTENT UPPER LEVEL SYSTEM EJECTS NORTHEAST INTO THE MIDDLE AND LOWER MISSISSIPPI VALLEY TONIGHT. ASSOCIATED SURFACE LOW PRESSURE WILL ALSO EJECT NORTHEAST INTO THE TN/OH VALLEYS BY SUNRISE WEDNESDAY. TRAILING COLD FRONT BY THE END OF TONIGHT WILL REACH A POSITION FROM NEAR NASHVILLE TN SOUTHWEST INTO THE LOWER MISSISSIPPI VALLEY. LINE OF SHOWERS AND THUNDERSTORMS WILL LIKELY BE PROGRESSING EASTWARD IN ADVANCE OF THIS FRONT THROUGH THE NIGHT. AT THIS TIME WOULD APPEAR THAT THE MAIN ROUND OF SHOWERS AND STORMS WILL REMAIN TO OUR WEST THROUGH THE NIGHT ALTHOUGH A FEW MORE ISOLATED SHOWERS/TSTORMS ARE POSSIBLE VERY LATE ACROSS THE EASTERN FL PANHANDLE INTO SOUTHEASTERN ALABAMA. WOULD EXPECT AN INCREASE IN CLOUDS FROM WEST TO EAST THROUGH THE NIGHT WITH A BREEZY SOUTHERLY WIND KEEPING LOW TEMPERATURES ON THE WARM SIDE. CURRENT GRIDS WILL SHOW LOWS AROUND 60 OR PERHAPS A FEW DEGREES WARMER INLAND AND MIDDLE AND UPPER 60S ALONG THE COAST. UPPER LEVEL SHORTWAVE ENERGY AND ASSOCIATED COLD FRONT WILL CONTINUE TO APPROACH THE AREA WEDNESDAY. COLD FRONT IS LIKELY TO REACH OUR WESTERN ZONES BY LATE IN THE DAY WITH A ROUND OF SHOWERS AND THUNDERSTORMS SPREADING EASTWARD IN ADVANCE. BEST ESTIMATE AT THE TIMING OF THE STEADIER SHOWERS/TSTORMS WILL BE FROM MID MORNING TO LATE AFTERNOON OVER OUR WESTERN ZONES AND DURING THE AFTERNOON AND EVENING HOURS OVER OUR EASTERN ZONES. COLD FRONT SHOULD EXIT THE SOUTHEAST FL BIG BEND AFTER MIDNIGHT WITH ANY LINGERING SHOWERS/STORMS COMING TO AN END DURING THE LATE NIGHT HOURS. ZONAL MID/UPPER LEVEL FLOW AND SURFACE HIGH PRESSURE WILL ESTABLISH BEHIND THE FRONT DURING THURSDAY WITH FAIR WEATHER AND SEASONABLE TEMPERATURES FOR THE END OF THE WORK WEEK. A QUICK LOOK AT ANY SEVERE THREAT WITH THE FRONTAL PASSAGE WEDNESDAY AND WEDNESDAY NIGHT. FAMILIAR SETUP TO THIS EVENT WITH THE USUAL BATTLE BETWEEN VERY FAVORABLE LOW LEVEL AND DEEP LAYER SHEAR PROFILES AND UNFAVORABLE INSTABILITY. FIRST WE WILL LOOK AT THE FAVORABLE SIDE...0-6KM DEEP LAYER BULK SHEAR IS QUITE IMPRESSIVE WITH MODEL CONSENSUS BETWEEN 55 AND 60 KTS AHEAD OF THE FRONT AND CERTAINLY ENOUGH TO MAINTAIN ENHANCED UPDRAFTS. IMPRESSIVE LOW LEVEL JET ALSO EXPECTED WITH GFS/SREF SHOWING WIDE SWATH OF 50-60 KNOTS AT 850MB. SUFFICIENT WIND PROFILES SHOULD BE IN PLACE...HOWEVER AS MENTIONED ABOVE THE INSTABILITY IS MARGINAL AT BEST. BUFKIT PROFILES ARE SHOWING FAIRLY WEAK LAPSE RATES IN THE MID LEVELS WITH SURFACE BASED INSTABILITY PEAKING IN THE 200-300 J/KG RANGE AND MU CAPES ONLY AROUND 400 J/KG. TAKING ALL THIS IN MIND...DO NOT EXPECT A WIDESPREAD SEVERE WX EVENT ON WEDNESDAY... HOWEVER WITH THE VERY STRONG SHEAR PROFILES...CAN NOT RULE OUT A FEW ISOLATED STRONG TO SEVERE CELLS/BOWING SEGMENTS IN LINE WITH THE LATEST FORECAST FROM THE STORM PREDICTION CENTER WHICH CONTINUES TO OUTLOOK OUR AREA FOR A SLIGHT RISK OF SEVERE WEATHER WITH THIS EVENT. MAIN THREATS WILL BE DAMAGING STRAIGHT LINE WINDS AND THE POSSIBILITY OF ISOLATED TORNADOES. DUE TO THE WEAK FORECAST LAPSE RATES AND INSTABILITY... WOULD APPEAR THE HAIL THREAT WILL BE MARGINAL AT BEST. WILL CONTINUE TO MONITOR THE SITUATION CLOSELY AS ANY TREND TOWARD HIGHER INSTABILITY WILL INCREASE THE OVERALL THREAT. && .LONG TERM... FAIR WEATHER WILL DOMINATE LONG TERM. STRONG ZONAL FLOW ALOFT WITH HIGH PRESSURE AT SURFACE WILL CONTINUE OVER FORECAST AREA WITH PERSISTENT DRY CONDITIONS THROUGH SATURDAY. ON SUNDAY...WEAK TROUGHING MOVING EWD INTO SE CONUS SHUNTED HIGH TOWARDS WRN ATLC. SHORTWAVE SYSTEM MOVES ACROSS THE SOUTHEAST STATES DRAGGING A WEAK COLD FRONT ACROSS CWA. 00Z GUIDANCE EVEN LESS IMPRESSIVE WITH SYSTEM THAN PREVIOUS RUN. WILL INCLUDE SLIGHT CHANCE POPS...MAINLY W HALF CWA IN PACKAGE. IN ITS WAKE...STRONG HIGH BUILDS SOUTH INTO REGION AND DRY CONDITIONS RETURN FOR EARLY WORK WEEK. IN WAKE OF INITIAL FRONT THAT EXITS CWA ON WED...MAX TEMPS REMAIN SEASONABLE EXCEPT FOR MODESTLY BELOW CLIMO ON SUN UNDER INFLUENCE OF CLOUDS ASSOCIATED WITH SECOND FRONT. MINS BEGIN BELOW CLIMO IN WAKE OF INITIAL FRONT AND THEN RISE TO NEAR CLIMO NEXT FEW NIGHTS BEFORE AGAIN DROPPING BELOW CLIMO SUN AND MON NIGHT IN WAKE OF SECOND FRONT. && .AVIATION... UNDER INCREASINGLY LOW LEVEL MOISTURE GENERATED BY WINDS VEERING TO STRONG EAST-SOUTHEAST FLOW....MVFR CIGS EXPECTED DURING PRE-DAWN HOURS THE REGION. THIS IS SUPPORTED BY BOTH THE NAM AND GFS AS WELL AS THE SREF PROBS. MAY ALSO SEE SOME LIGHT BR AT AREA TERMINALS STRENGTH OF BOUNDARY LAYER WINDS SHOULD KEEP CONDS ABOVE IFR. AFTER DAYBREAK...SHOULD SEE MVFR CIGS LIFT AND GRADUALLY SCATTER BY 15Z WITH BREEZY VFR CONDITIONS PREVAILING THROUGH THE REMAINDER OF THE TAF CYCLE. CLOUD DECKS WILL BEGIN TO LOWER FROM W-E AHEAD OF NEXT WEATHER MAKER AFTER MIDNIGHT BUT REMAIN ABOVE VFR THRU 06Z. && .MARINE... TIGHT GRADIENT BETWEEN HIGH PRESSURE TO OUR NORTHEAST AND LOW PRESSURE TO OUR WEST WILL KEEP WINDS ELEVATED OVER THE MARINE AREA TODAY. THESE WINDS AND SEAS ARE EXPECTED TO RISE TO ADVISORY LEVELS DURING THE DAY...ESPECIALLY ACROSS THE WESTERN LEGS. AS A COLD FRONT BEGINS TO APPROACH FROM THE WEST TONIGHT...ADVISORY LEVEL WINDS AND SEAS WILL BE MAINTAINED AND EXPAND EASTWARD TO COVER ALL OF THE FORECAST WATERS. COLD FRONT WILL CROSS THE WATERS LATER WEDNESDAY AND WEDNESDAY NIGHT WITH A LIKELY ROUND OF SHOWERS AND THUNDERSTORMS. ELEVATED WINDS AND SEAS WILL LINGER EVEN BEHIND THE FRONT INTO THE DAY ON THURSDAY BEFORE BEGINNING TO SUBSIDE LATE IN THE WEEK AS HIGH PRESSURE BUILDS TO THE NORTH. && .FIRE WEATHER... LOW LEVEL MOISTURE WILL BE ON THE INCREASE DURING THE NEXT 36 HOURS WITH RH VALUES REMAINING ABOVE CRITICAL LEVELS. CRITICAL FIRE WEATHER CONDITIONS ARE ANTICIPATED TO RETURN TO PORTIONS OF THE AREA BY THURSDAY AFTERNOON BEHIND A COLD FRONT LATER WEDNESDAY AND WEDNESDAY NIGHT. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 79 61 76 51 72 / 0 05 70 60 0 PANAMA CITY 78 65 75 51 71 / 0 20 70 40 0 DOTHAN 79 61 73 45 73 / 0 20 70 40 0 ALBANY 78 61 76 48 74 / 0 10 70 50 0 VALDOSTA 78 59 81 52 74 / 0 05 50 70 05 CROSS CITY 80 60 81 57 73 / 0 0 30 60 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...FIRE WEATHER WATCH IN EFFECT FOR THURSDAY AFTERNOON FOR SOUTHEAST ALABAMA. GA...FIRE WEATHER WATCH IN EFFECT FOR PORTIONS OF SOUTHWEST GEORGIA THURSDAY AFTERNOON. FL...FIRE WEATHER WATCH IN EFFECT FOR THURSDAY AFTERNOON FOR ALL OF THE EASTERN FLORIDA PANHANDLE AND FLORIDA BIG BEND. GM...SMALL CRAFT ADVISORY IN EFFECT THROUGH WEDNESDAY EVENING FOR THE FOLLOWING ZONES: COASTAL WATERS FROM OCHLOCKONEE RIVER TO APALACHICOLA FL OUT TO 20 NM...COASTAL WATERS FROM APALACHICOLA TO DESTIN FL OUT 20 NM...WATERS FROM SUWANNEE RIVER TO APALACHICOLA FL FROM 20 TO 60 NM...WATERS FROM APALACHICOLA TO DESTIN FL FROM 20 TO 60 NM. && $$ AVIATION/FIRE WX/LONG TERM...BLOCK PUBLIC/MARINE...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 919 AM EDT MON MAR 17 2008 .SYNOPSIS...WATER VAPOR IMAGERY AND RUC H5 CONTINUE TO SHOW AN AMPLIFYING UPPER PATTERN ACROSS THE STATES WITH A RIDGE BUILDING ACROSS THE EASTERN HALF OF THE COUNTRY AND A LARGE UPPER LOW OUT WEST OVER THE FOUR CORNERS REGION. THE MORNING SURFACE ANALYSIS SHOWED A RIDGE AXIS EXTENDING NORTH TO SOUTH ALONG THE EAST COAST AND A DEVELOPING LOW PRESSURE SYSTEM AND COLD FRONT OUT WEST OVER OK/TX. THIS SURFACE RIDGE WILL PUSH EAST AND OFF THE COAST TODAY ALLOWING THE LOCAL WINDS TO VEER AROUND TOWARD THE SOUTHEAST. THE GRADIENT BETWEEN THE DEVELOPING LOW OUT WEST AND THIS RIDGE WILL CONTINUE TO TIGHTEN ACROSS THE AREA TODAY...WHICH WILL ALLOW THE SE WINDS TO BECOME QUITE GUSTY...ESPECIALLY ACROSS THE COASTAL WATERS. TLH VAD WIND PROFILE (VWP) IS SHOWING UP TO 45 KNOTS (52 MPH) JUST ABOVE THE SURFACE FROM ONE TO TWO KFT. THROUGH THE REST OF THE DAY...THE PLEASANT WEATHER CONDITIONS WILL CONTINUE WITH AFTERNOON HIGHS CLIMBING BACK INTO THE UPPER 70S. WILL ONLY MAKE A FEW MINOR TWEAKS IN THE GRIDS WITH NO MAJOR UPDATES EXPECTED AT THIS TIME. && .AVIATION...VFR CONDITIONS TO CONTINUE THROUGH THE DAY TODAY. ONLY WEATHER OF CONCERN WILL BUT GUSTY WINDS DURING THE DAY AND LOW LEVEL WIND SHEAR THIS MORNING. VWP DATA SHOWS 40KT AT 1KFT AND 5KT OR LESS AT THE SFC. THIS SHOULD MIX OUT BY 10AM. OTHERWISE...HIGH CLOUDS WILL GRADUALLY INCREASE TODAY AND TONIGHT AS DEVELOPING STORM TAKES SHAPE OVER TEXAS. && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING FROM 3 PM THIS AFTERNOON TO 7 PM EDT THIS EVENING FOR THE FOLLOWING ZONES: GADSDEN...JEFFERSON... LAFAYETTE...LEON...MADISON...TAYLOR...WAKULLA. GM...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR THE FOLLOWING ZONES: APALACHEE BAY OR COASTAL WATERS FROM KEATON BEACH TO OCHLOCKONEE RIVER FL OUT TO 20 NM...COASTAL WATERS FROM SUWANNEE RIVER TO KEATON BEACH OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 4 PM EDT WEDNESDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM OCHLOCKONEE RIVER TO APALACHICOLA FL OUT TO 20 NM...COASTAL WATERS FROM APALACHICOLA TO DESTIN FL OUT 20 NM...WATERS FROM SUWANNEE RIVER TO APALACHICOLA FL FROM 20 TO 60 NM...WATERS FROM APALACHICOLA TO DESTIN FL FROM 20 TO 60 NM. && $$ GIBBS/CAMP fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 110 PM CDT TUE MAR 18 2008 .DISCUSSION... ISSUED 1045 AM CDT TUE MAR 18 2008 WILL CONTINUE THE FLOOD WATCH SE OF I-55 THROUGH TONIGHT AND ALSO CONTINUE THE DENSE FOG ADVISORY ALONG AND NW OF I-55 THROUGH 2 PM TODAY. WILL COOL HIGH TEMPERAUTRES A FEW DEGREES IN SE IL DUE TO THE WIDESPREAD MODERATE TO HEAVY RAIN TODAY. SE IL COULD SEE 1.5 TO 3 INCHES OF RAIN GOING INTO THIS EVENING AND THIS ON TOP OF THE 1.25 TO 1.75 INCHES ALREADY RECEIVED SINCE MIDNIGHT. 15Z/10 AM SURFACE MAP SHOWS 998 MB LOW PRESSURE OVER SOUTH TX. A FRONTAL BOUNDARY EXTENDS FROM THE LOW ACROSS CENTRAL TX TO 1004 MB LOW PRESSURE IN FAR WEST CENTRAL AR. THE FRONT THEN EXTENDS ACROSS NW IL JUST NW OF THE IL RIVER. 1010 MB LOW PRESSURE WAS ALONG THIS FRONT JUST EAST OF QUINCY WITH A WARM FRONT OVER FAR SW IL INTO CENTRAL KY. A CONVEYOR BELT OF MODERATE TO HEAVY RAIN SHOWERS EXTENDED FROM TX ACROSS CENTRAL/SE MO AND SOUTHERN PARTS OF IL/IN/OH INTO SW PA. RADAR MOSAIC SHOWS RAIN SOUTH OF TAYLORVILLE TO PARIS LINE WITH SCATTERED THUNDERSTORMS AND HEAVY RAINS FROM I-70 SOUTH. WIDESPREAD DENSE FOG ALONG AND WEST OF I-55 INTO SE IA WHERE VSBYS LESS THAN A HALF MILE. TEMPS RANGE FROM THE LOWER 40S FROM THE IL RIVER NW TO THE LOWER 50S FROM I-72 SOUTH. ALOFT A STRONG 555 DM 500 MB LOW WAS JUST SW OF TX WITH A HIGHLY AMPLIFIED UPPER LEVEL FLOW OVER THE U.S. WITH UPPER LEVEL RIDGE OVER THE EASTERN STATES AND WEST COAST AND UPPER LEVEL TROF OVER THE CENTRAL PART OF THE COUNTRY. RUC AND WRF MODELS SHOW THE FRONTAL BOUNDARY SLIPPING SE THROUGH IL THIS AFTERNOON WHILE TWO SURFACE LOWS IN SOUTH TX AND WESTERN AR MOVES UP ALONG THE FRONT INTO THE OHIO VALLEY THROUGH WED AS UPPER LEVEL TROF MOVES INTO IL. THIS TO KEEP ROUNDS OF HEAVY RAINS OVER SE IL INTO WED MORNING. HEAVIEST RAINS TO OCCUR THIS AFTERNOON AND EVENING OVER SE IL WHERE 1.5 TO 3 INCHES OF RAIN FROM I-70 SOUTH TO THE OHIO RIVER. RAIN CHANCES DIMINISH TO LESS THAN 30 PERCENT OVER NW IL TODAY WHICH WILL BE ON NW FRINGE OF STORM SYSTEM. WIDESPREAD DENSE FOG SHOULD LIFT BY MID AFTERNOON AS FRONT SLIP SE THROUGH CENTRAL IL WITH LIGHT TO CALM WINDS BECOMING NW AROUND 10 KTS. TEMPS WILL NOT CLIMB TO MUCH TODAY WITH ALL THE CLOUDS AND RAIN AROUND. HIGHS RANGE FROM THE MID 40S FROM THE IL RIVER NW TO THE LOWER 60S IN SE IL. HUETTL && .AVIATION... ISSUED 100 PM CDT TUE MAR 18 2008 FOG...DENSE AT BMI WITH VSBY 1/8 MILE...WILL LIFT ALONG AND WEST OF I-55 THROUGH 20Z. RAIN WILL SPREAD NORTH ACROSS AREAS ALONG AND EAST OF I-55 THROUGH MID AFTERNOON WITH VSBYS RESTRICTED TO 2 TO 4 MILES. LOW CIELINGS BELOW 1K FT SHOULD PREVAIL THROUGH TONIGHT ACROSS CENTRAL IL TAF SITES. RAIN WILL DIMINISH BY MID WED MORNING EAST OF I-55. CEILING FROM 1 TO 2K FT AFTER 14Z WED MORNING EXCEPT SCATTERING OUT AT PIA. A FRONTAL BOUNDARY JUST EAST OF THE IL RIVER WILL MOVE INTO EASTERN IL DURING MID AFTERNOON. WINDS WILL BECOME NW 5 TO 10 KTS THEN TURN NORTH AND INCREASE TO 10 TO 15 KTS TONIGHT AS 1002 MB LOW PRESSURE OVER WEST CENTRAL AR AND 999 MB LOW PRESSURE IN SOUTH TX MOVES UP ALONG THE FRONT MOVING INTO THE OHIO VALLEY WED. WIDESPREAD RAIN SHOWERS WILL SPREAD NE ACROSS AREAS ALONG AND EAST OF I-55 THROUGH MID AFTERNOON AND CONTINUE TONIGHT. COULD BE ISOLATED THUNDER AS FAR NORTH AS I-72 LATE THIS AFTERNOON AND EVENING WHERE RAIN WILL BE HEAVIER AND REDUCE VSBYS MORE. HUETTL && .PREV DISCUSSION... ISSUED 415 AM CDT TUE MAR 18 2008 SHORT TERM...TODAY THROUGH THURSDAY. WV SAT IMAGERY SHOWS UPPER LOW OVER SOUTHERN CHIHUAHUA... FINALLY FINISHED WITH ITS SOUTHWARD DIGGING... AND GETTING READY TO DRIFT NORTHEASTWARD TOWARDS TEXAS. AHEAD OF THIS LOW... PLENTY OF DEEP MID/UPPER LEVEL MOISTURE FROM THE PACIFIC... AS WELL AS DEEP LOW LEVEL MOISTURE FROM THE GULF OF MEXICO CONTINUES TO STREAM NORTHWARD. THIS HAS RESULTED IN A STEADY STREAM OF MODERATE TO HEAVY PRECIPITATION STRETCHING FROM SOUTH OF THE BIG BEND ALL THE WAY INTO SOUTHERN OHIO. RADAR TRENDS OVERNIGHT INDICATE THE AXIS OF HEAVIER PRECIPITATION UP IN THIS NECK OF THE WOODS HAS DRIFTED MAINLY SOUTH OF THE I-70 CORRIDOR...QUITE OUT OF WHACK WITH THE 00Z NAM AND GFS QPF PREDICTIONS. 00Z GEM REGIONAL MODEL HAS HANDLED THE OVERNIGHT SITUATION MUCH BETTER... AND ACTUALLY SUGGESTS KEEPING THE FOCUS OF HEAVIER PRECIP AMOUNTS SOUTH OF I-70 THROUGH TODAY. STILL THINK PRECIP AXIS WILL TEND TO BUILD BACK NORTHWESTWARD TOWARDS THE SFC FRONT LATER TODAY...GIVEN CONTINUED SUPPLY OF AMPLE MOISTURE...SEVERAL DISTURBANCES EJECTING NORTHEAST OVER THE AREA... AND INCREASING UPPER LEVEL DIVERGENCE AS AREA REMAINS IN THE RRQ OF A STRENGTHENING JET OVER THE LOWER GREAT LAKES. DESPITE THE EARLY GOOD PERFORMANCE OF THE GEM-REGIONAL... NEED TO HEDGE TOWARDS THE NAM/GFS/ECMWF SOLUTIONS FOR LATER THIS AFTERNOON IN LIGHT OF THE AFOREMENTIONED FAVORABLE OBSERVED CONDITIONS. ALSO EXPECT SCATTERED SHOWERS AND AREAS OF DRIZZLE TO CONTINUE MUCH OF THE DAY ALONG/NORTHWEST OF THE ILLINOIS RIVER. KEPT THE WESTERN HALF OF THE CWA IN THE FLOOD WATCH THROUGH 12Z WED. THOUGH IT IS CLEAR THAT THE GREATEST THREAT AND GREATEST QPF WILL BE SOUTH OF I-70...RAINFALL AMOUNTS COULD STILL RANGE BETWEEN 0.75-1.50 INCHES FARTHER NORTH... WITH 2 TO 4 INCHES+ POSSIBLE SOUTH OF I-70. BY LATE TONIGHT... PRECIP FOCUS WILL SHIFT TO THE SOUTHEAST... WITH ANY REMAINING RAINFALL WEDNESDAY MORNING LIKELY ONLY AFFECTING THE EXTREME SOUTHEAST CORNER OF THE CWA. PULLED BACK ON TEMPS ACROSS THE WESTERN HALF OF THE CWA IN LIGHT OF CURRENT TEMPS AND OVERCAST CONDITIONS. INCREASING SSE SFC FLOW EAST OF I-57 SUGGESTS CMI/DNV AREA MAY STILL CRACK THE LOWER 50S DESPITE PRECIP/CLOUD COVER... BUT THE NORTHERN AND WESTERN EXTEND OF THIS WARM ADVECTION HAS TO END SOMEWHERE... AND THINK IT WILL NOT QUITE WRAP INTO THE BMI AREA. LONG TERM...THURSDAY NIGHT THROUGH SATURDAY NIGHT. WHILE THE OVERALL PATTERN IS WELL AGREED UPON BETWEEN THE MEDIUM RANGE MODELS... MUCH OF THE MIDWEST IS LEFT IN A LIMP QUASI-ZONAL FLOW THROUGH THE END OF THE WEEK... AND GUIDANCE IS BEGINNING TO SHOW DIFFERENCES OF OPINION IN THE TIMING OF A COUPLE OF WEAK/POORLY AMPLIFIED SHORTWAVES RIPPLING THROUGH THE FLOW. GFS IS THE WETTEST OF THE GUIDANCE... BUT CONTINUED TO SIDE CLOSER THE ECMWF AND PREV FORECAST PACKAGE...WHICH SUGGEST THE BETTER SHOT AT PRECIP WILL HOLD OFF UNTIL THURSDAY NIGHT INTO FRIDAY. COULD SEE A MIX OF RAIN/SNOW FOR A BRIEF PERIOD THURSDAY NIGHT INTO FRI MORNING ACROSS THE FAR NORTH... BUT AS MENTIONED YESTERDAY... WHERE THE BAROCLINIC ZONE DECIDES TO SET UP WILL BE KEY BOTH IN TERMS OF P-TYPE AND BEST PRECIP CHANCES... WHICH COULD END UP NORTH OF I-74. HARDIMAN && .ILX WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH THROUGH WEDNESDAY MORNING FOR ILZ044>046-052>057- 061>063-066>068-071>073. DENSE FOG ADVISORY UNTIL 2 PM CDT THIS AFTERNOON FOR ILZ027>031- 036>038-040>043-047>051. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1204 AM CDT TUE MAR 18 2008 .AVIATION... 06Z TAFS...ICT/SLN/HUT/CNU/RSL...BACK EDGE OF LOW CLOUDS/VISIBILITIES WILL PUSH EAST ACROSS THE AREA AS THE NIGHT PROGRESSES...AS FRONTAL BOUNDARY CONTINUES TO MARCH SLOWLY EAST. SOUTHEAST KANSAS WILL STAY IN THE GRUNGE THE LONGEST. OTHERWISE...CONVERGENCE ALONG ELEVATED FRONTAL BOUNDARY WILL RESULT IN AREAS OF SHOWERS/THUNDERSTORMS OVER SOUTHEAST KANSAS THROUGH THE OVERNIGHT HOURS. WILL MAKE TIMELY AMENDMENTS WHEN/WHERE NECESSARY. KLEINSASSER && .PREV DISCUSSION... /ISSUED 918 PM CDT MON MAR 17 2008/ UPDATE... STORMS MOVING NORTH/NORTHEAST OUT OF OKLAHOMA APPEAR TO BE ROOTED ALONG THE 850MB FRONTAL/CONVERGENCE ZONE. ADDITIONALLY...ACTIVITY IS LIKELY BEING AIDED BY LIFT IN RIGHT ENTRANCE REGION OF UPPER JET...COMBINED WITH SUBTLE SHORTWAVE ENERGY PROGRESSING ACROSS WEST TEXAS. ALL SHORT AND MEDIUM RANGE MODEL GUIDANCE SUGGESTS ELEVATED INSTABILITY DROPS OFF QUITE A BIT WITH NORTHWARD EXTENT...WITH THE HIGHEST VALUES ONLY APPROACHING 500 J/KG ACROSS SOUTHERN PORTIONS OF SOUTH-CENTRAL AND SOUTHEAST KANSAS. WITH THAT SAID...THINKING SHOWERS/THUNDERSTORMS WILL MOVE NORTH/NORTHEAST OUT OF OKLAHOMA ALONG LOW-LEVEL CONVERGENCE ZONE...TARGETING LOCATIONS GENERALLY EAST OF THE TURNPIKE. DEGREE OF INSTABILITY AND CLOUD-BEARING SHEAR WILL BE ENOUGH TO PRODUCE DIME/NICKEL SIZED HAIL IN THE STRONGEST CORES. THREAT WILL GRADUALLY SHIFT INTO JUST SOUTHEAST KANSAS AFTER MIDNIGHT. AS FAR AS HEAVY RAIN GOES...THINKING BULK OF ACTIVITY WILL REMAIN ACROSS EASTERN OKLAHOMA...SOUTHERN MISSOURI AND ARKANSAS...WHERE BEST LOW-LEVEL MOISTURE...INSTABILITY AND CONVERGENCE RESIDES. HOWEVER...NUMEROUS THUNDERSTORMS MAY CLIP FAR SOUTHEAST KANSAS LATER TONIGHT...INCREASING THE CHANCE FOR LOCALIZED MINOR FLOODING. FARTHER NORTHWEST...NEARLY SATURATED LOW-LEVELS AND WEAK LIFT WILL PROMOTE AREAS OF DRIZZLE AND LOW CLOUDS MUCH OF THE NIGHT. KLEINSASSER PREV DISCUSSION... /ISSUED 702 PM CDT MON MAR 17 2008/ AVIATION... 00Z TAFS...ICT/SLN/HUT/CNU/RSL...LOW CLOUDS AND REDUCED VISIBILITIES SHOULD GRADUALLY IMPROVE LATE TONIGHT AND TUESDAY MORNING FROM NORTHWEST TO SOUTHEAST...AS LOW-LEVEL DRY AIR ADVECTION COMMENCES SLOWLY IN WAKE OF COLD FRONT CURRENTLY PROGRESSING ACROSS OKLAHOMA/SOUTHEAST KANSAS. HOWEVER...CONFIDENCE REMAINS LOW ON EXACTLY WHEN THE CIGS/VSBYS WILL BEGIN TO IMPROVE LATER TONIGHT...ALONG WITH HOW MUCH THEY`LL IMPROVE. WILL MAKE TIMELY AMENDMENTS WHEN/WHERE NECESSARY. ADDITIONALLY...NUMEROUS SHOWERS/THUNDERSTORMS ARE ANTICIPATED THROUGH THE OVERNIGHT HOURS ACROSS EASTERN OKLAHOMA...ARKANSAS AND MISSOURI...AS MOISTURE CONVERGENCE INCREASES ALONG PROGRESSING FRONT...IN COMBINATION WITH INCREASING LOW-LEVEL JET. SOME OF THIS ACTIVITY COULD CLIP FAR SOUTHEAST KANSAS THROUGH THE OVERNIGHT HOURS. KLEINSASSER PREV DISCUSSION... /ISSUED 321 PM CDT MON MAR 17 2008/ DISCUSSION... FORECAST CHALLENGES WILL BE PRECIP CHANCES AND ASSOCIATED FLOODING FOR THE FIRST COUPLE OF PERIODS. SYNOPSIS: IN THE UPPER LEVELS CURRENTLY HAVE A POWERFUL UPPER LOW SITUATED OVER THE DESERT SOUTHWEST WITH WATER VAPOR IMAGERY SHOWING A NICE SUBTROPICAL MOISTURE FETCH INTO THE CENTRAL PLAINS. AT THE SURFACE A LOW IS LOCATED OVER SW TX WITH A COLD FRONT/TROUGH STRETCHING FROM NORTHWEST MO THROUGH CENTRAL OK. TONIGHT-TUE: THE UPPER LOW TO OUR SOUTHWEST IS EXPECTED TO MEANDER VERY SLOWLY EAST THIS EVENING AS LOW LEVEL MOISTURE CONTINUES TO PUMP INTO THE SOUTHERN PLAINS. SHORT RANGE MODELS(INCLUDING RUC) ARE IN GOOD AGREEMENT REGARDING QPF LOCATION OVER THE NEXT 12 HOURS WHICH DOES LEAD TO SOME CONFIDENCE. MOISTURE TRANSPORT OFF OF THE 300K SURFACE WILL SHIFT EAST OVERNIGHT...PLACING THE HIGHEST PRECIP TOTALS AND FLOODING OVER SOUTHERN MO AND AR. SO NOT PLANNING ANY FLOOD WATCHES AT THIS TIME WITH THE THINKING THAT PRECIP OVER SE KS MAY CAUSE SOME MINOR FLOODING OF FLOOD PRONE AREAS AT BEST...WITH THE MORE SIGNIFICANT FLOODING OCCURRING TO OUR EAST. NOT TOO IMPRESSED WITH SEVERE POTENTIAL OVER THE NEXT SEVERAL HOURS. SINCE WE`VE STAYED GRUNGED-OUT WITH LOW CLOUDS AND SHOWERS/STORMS...INSTABILITY IS VERY LIMITED. IN ADDITION MODELS ARE NOT SHOWING MUCH ELEVATED INSTABILITY. THEREFORE CURRENT THINKING IS THAT SPEED SHEAR FROM 850MB-500MB MAYBE GOOD ENOUGH TO PRODUCE SOME DIME TO NICKLE SIZE HAIL OVER SE KS. BY TUE AFTERNOON THE UPPER LOW WILL BE SITUATED OVER EXTREME SW TX WITH THE SURFACE TROUGH/COLD FRONT EXTENDING FROM THE ARKLATEX REGION INTO THE OZARKS. IN THE UPPER LEVELS A STRONG JET WILL BE TRACKING OVER THE NORTHERN MISSISSIPPI VALLEY PLACING THE OZARK REGION IN THE RIGHT ENTRANCE REGION OF THIS JET WITH THE MODELS RESPONDING TO THIS BY BACKING THE 850MB FLOW WHICH SHOULD ENHANCE LOW LEVEL CONVERGENCE AND PRECIP COVERAGE TO OUR EAST. FOR OUR AREA ONLY EXTREME SE KS WILL HAVE A SHOT AT ADDITIONAL PRECIP WITH THE REMAINDER OF THE AREA STAYING DRY ON TUE. WED-THU: STRONG UPPER LOW WILL MOVE INTO THE SOUTHERN MISSISSIPPI VALLEY BY WED AFTERNOON AS ANOTHER MUCH WEAKER UPPER PIECE OF ENERGY TRACKS ACROSS THE NORTHERN PLAINS. THIS SET-UP WILL ALLOW THE FORECAST AREA TO DRY OUT. FOR THU THE UPPER PATTERN WILL FLATTEN ALLOWING ABOVE NORMAL TEMPS TO PREVAIL ACROSS THE AREA. FRI-MON: UPPER PATTERN WILL REMAIN FAIRLY ZONAL THROUGH SAT WITH BOTH THE ECMWF AND GFS SWINGING THROUGH A FAST MOVING PIECE OF ENERGY ACROSS THE NORTHERN PLAINS AND INTO MO BY SUN MORNING. THIS FEATURE MAY SPARK OFF SOME PRECIP SAT INTO SAT NIGHT WHICH THE PREVIOUS FORECAST ALREADY HAD IN. IN ADDITION BOTH THE ECMWF AND GFS ARE SPILLING SOME COOLER AIR INTO THE AREA FOR SAT AS THIS SYSTEM DEPARTS. WITH THIS WAVE WELL TO OUR EAST ON SUN...SURFACE HIGH WILL SLIDE-IN OVER THE CENTRAL PLAINS. THEREFORE WENT AHEAD TOOK PRECIP OUT OF FORECAST FOR SUN. WHILE CONFIDENCE IN PRECIP CHANCES ARE LOW FOR MON...AM FAIRLY CONFIDENT THAT THERE WILL BE SOME LEE TROUGHING AND ABOVE NORMAL TEMPS. LAWSON AVIATION... 18Z TAFS...MOIST UPSLOPE FLOW HAS LED TO LIFR CONDITIONS AT SEVERAL SITES AND THIS WILL LIKELY CONTINUE THROUGHOUT THE AFTERNOON AND INTO THE EVENING. PRECIPITATION WILL BE MOST LIKELY AT KICT AND KCNU...WITH PERSISTENT LOW CLOUDS ELSEWHERE. WITH ASSOCIATED UPPER SYSTEM BEING SLOW TO MOVE OUT...CLEARING WILL BE VERY SLOW...WITH ONLY PARTIAL CLEARING AT NORTHWEST SITES ON TUE MORNING. -HOWERTON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 39 54 36 64 / 40 10 0 0 HUTCHINSON 34 55 36 63 / 20 10 0 0 NEWTON 37 54 36 63 / 30 10 0 10 ELDORADO 39 53 36 62 / 50 10 0 10 WINFIELD-KWLD 42 52 37 64 / 60 10 0 10 RUSSELL 32 55 30 64 / 10 10 0 0 GREAT BEND 32 55 32 64 / 10 10 0 0 SALINA 35 55 36 63 / 20 10 0 10 MCPHERSON 35 55 36 63 / 20 10 0 0 COFFEYVILLE 46 53 35 61 / 90 50 20 10 CHANUTE 44 51 35 60 / 90 40 20 10 IOLA 42 51 35 60 / 90 30 20 10 PARSONS-KPPF 45 52 35 61 / 90 50 20 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 918 PM CDT MON MAR 17 2008 .UPDATE... STORMS MOVING NORTH/NORTHEAST OUT OF OKLAHOMA APPEAR TO BE ROOTED ALONG THE 850MB FRONTAL/CONVERGENCE ZONE. ADDITIONALLY...ACTIVITY IS LIKELY BEING AIDED BY LIFT IN RIGHT ENTRANCE REGION OF UPPER JET...COMBINED WITH SUBTLE SHORTWAVE ENERGY PROGRESSING ACROSS WEST TEXAS. ALL SHORT AND MEDIUM RANGE MODEL GUIDANCE SUGGESTS ELEVATED INSTABILITY DROPS OFF QUITE A BIT WITH NORTHWARD EXTENT...WITH THE HIGHEST VALUES ONLY APPROACHING 500 J/KG ACROSS SOUTHERN PORTIONS OF SOUTH-CENTRAL AND SOUTHEAST KANSAS. WITH THAT SAID...THINKING SHOWERS/THUNDERSTORMS WILL MOVE NORTH/NORTHEAST OUT OF OKLAHOMA ALONG LOW-LEVEL CONVERGENCE ZONE...TARGETING LOCATIONS GENERALLY EAST OF THE TURNPIKE. DEGREE OF INSTABILITY AND CLOUD-BEARING SHEAR WILL BE ENOUGH TO PRODUCE DIME/NICKEL SIZED HAIL IN THE STRONGEST CORES. THREAT WILL GRADUALLY SHIFT INTO JUST SOUTHEAST KANSAS AFTER MIDNIGHT. AS FAR AS HEAVY RAIN GOES...THINKING BULK OF ACTIVITY WILL REMAIN ACROSS EASTERN OKLAHOMA...SOUTHERN MISSOURI AND ARKANSAS...WHERE BEST LOW-LEVEL MOISTURE...INSTABILITY AND CONVERGENCE RESIDES. HOWEVER...NUMEROUS THUNDERSTORMS MAY CLIP FAR SOUTHEAST KANSAS LATER TONIGHT...INCREASING THE CHANCE FOR LOCALIZED MINOR FLOODING. FARTHER NORTHWEST...NEARLY SATURATED LOW-LEVELS AND WEAK LIFT WILL PROMOTE AREAS OF DRIZZLE AND LOW CLOUDS MUCH OF THE NIGHT. KLEINSASSER && .PREV DISCUSSION... /ISSUED 702 PM CDT MON MAR 17 2008/ AVIATION... 00Z TAFS...ICT/SLN/HUT/CNU/RSL...LOW CLOUDS AND REDUCED VISIBILITIES SHOULD GRADUALLY IMPROVE LATE TONIGHT AND TUESDAY MORNING FROM NORTHWEST TO SOUTHEAST...AS LOW-LEVEL DRY AIR ADVECTION COMMENCES SLOWLY IN WAKE OF COLD FRONT CURRENTLY PROGRESSING ACROSS OKLAHOMA/SOUTHEAST KANSAS. HOWEVER...CONFIDENCE REMAINS LOW ON EXACTLY WHEN THE CIGS/VSBYS WILL BEGIN TO IMPROVE LATER TONIGHT...ALONG WITH HOW MUCH THEY`LL IMPROVE. WILL MAKE TIMELY AMENDMENTS WHEN/WHERE NECESSARY. ADDITIONALLY...NUMEROUS SHOWERS/THUNDERSTORMS ARE ANTICIPATED THROUGH THE OVERNIGHT HOURS ACROSS EASTERN OKLAHOMA...ARKANSAS AND MISSOURI...AS MOISTURE CONVERGENCE INCREASES ALONG PROGRESSING FRONT...IN COMBINATION WITH INCREASING LOW-LEVEL JET. SOME OF THIS ACTIVITY COULD CLIP FAR SOUTHEAST KANSAS THROUGH THE OVERNIGHT HOURS. KLEINSASSER PREV DISCUSSION... /ISSUED 321 PM CDT MON MAR 17 2008/ DISCUSSION... FORECAST CHALLENGES WILL BE PRECIP CHANCES AND ASSOCIATED FLOODING FOR THE FIRST COUPLE OF PERIODS. SYNOPSIS: IN THE UPPER LEVELS CURRENTLY HAVE A POWERFUL UPPER LOW SITUATED OVER THE DESERT SOUTHWEST WITH WATER VAPOR IMAGERY SHOWING A NICE SUBTROPICAL MOISTURE FETCH INTO THE CENTRAL PLAINS. AT THE SURFACE A LOW IS LOCATED OVER SW TX WITH A COLD FRONT/TROUGH STRETCHING FROM NORTHWEST MO THROUGH CENTRAL OK. TONIGHT-TUE: THE UPPER LOW TO OUR SOUTHWEST IS EXPECTED TO MEANDER VERY SLOWLY EAST THIS EVENING AS LOW LEVEL MOISTURE CONTINUES TO PUMP INTO THE SOUTHERN PLAINS. SHORT RANGE MODELS(INCLUDING RUC) ARE IN GOOD AGREEMENT REGARDING QPF LOCATION OVER THE NEXT 12 HOURS WHICH DOES LEAD TO SOME CONFIDENCE. MOISTURE TRANSPORT OFF OF THE 300K SURFACE WILL SHIFT EAST OVERNIGHT...PLACING THE HIGHEST PRECIP TOTALS AND FLOODING OVER SOUTHERN MO AND AR. SO NOT PLANNING ANY FLOOD WATCHES AT THIS TIME WITH THE THINKING THAT PRECIP OVER SE KS MAY CAUSE SOME MINOR FLOODING OF FLOOD PRONE AREAS AT BEST...WITH THE MORE SIGNIFICANT FLOODING OCCURRING TO OUR EAST. NOT TOO IMPRESSED WITH SEVERE POTENTIAL OVER THE NEXT SEVERAL HOURS. SINCE WE`VE STAYED GRUNGED-OUT WITH LOW CLOUDS AND SHOWERS/STORMS...INSTABILITY IS VERY LIMITED. IN ADDITION MODELS ARE NOT SHOWING MUCH ELEVATED INSTABILITY. THEREFORE CURRENT THINKING IS THAT SPEED SHEAR FROM 850MB-500MB MAYBE GOOD ENOUGH TO PRODUCE SOME DIME TO NICKLE SIZE HAIL OVER SE KS. BY TUE AFTERNOON THE UPPER LOW WILL BE SITUATED OVER EXTREME SW TX WITH THE SURFACE TROUGH/COLD FRONT EXTENDING FROM THE ARKLATEX REGION INTO THE OZARKS. IN THE UPPER LEVELS A STRONG JET WILL BE TRACKING OVER THE NORTHERN MISSISSIPPI VALLEY PLACING THE OZARK REGION IN THE RIGHT ENTRANCE REGION OF THIS JET WITH THE MODELS RESPONDING TO THIS BY BACKING THE 850MB FLOW WHICH SHOULD ENHANCE LOW LEVEL CONVERGENCE AND PRECIP COVERAGE TO OUR EAST. FOR OUR AREA ONLY EXTREME SE KS WILL HAVE A SHOT AT ADDITIONAL PRECIP WITH THE REMAINDER OF THE AREA STAYING DRY ON TUE. WED-THU: STRONG UPPER LOW WILL MOVE INTO THE SOUTHERN MISSISSIPPI VALLEY BY WED AFTERNOON AS ANOTHER MUCH WEAKER UPPER PIECE OF ENERGY TRACKS ACROSS THE NORTHERN PLAINS. THIS SET-UP WILL ALLOW THE FORECAST AREA TO DRY OUT. FOR THU THE UPPER PATTERN WILL FLATTEN ALLOWING ABOVE NORMAL TEMPS TO PREVAIL ACROSS THE AREA. FRI-MON: UPPER PATTERN WILL REMAIN FAIRLY ZONAL THROUGH SAT WITH BOTH THE ECMWF AND GFS SWINGING THROUGH A FAST MOVING PIECE OF ENERGY ACROSS THE NORTHERN PLAINS AND INTO MO BY SUN MORNING. THIS FEATURE MAY SPARK OFF SOME PRECIP SAT INTO SAT NIGHT WHICH THE PREVIOUS FORECAST ALREADY HAD IN. IN ADDITION BOTH THE ECMWF AND GFS ARE SPILLING SOME COOLER AIR INTO THE AREA FOR SAT AS THIS SYSTEM DEPARTS. WITH THIS WAVE WELL TO OUR EAST ON SUN...SURFACE HIGH WILL SLIDE-IN OVER THE CENTRAL PLAINS. THEREFORE WENT AHEAD TOOK PRECIP OUT OF FORECAST FOR SUN. WHILE CONFIDENCE IN PRECIP CHANCES ARE LOW FOR MON...AM FAIRLY CONFIDENT THAT THERE WILL BE SOME LEE TROUGHING AND ABOVE NORMAL TEMPS. LAWSON AVIATION... 18Z TAFS...MOIST UPSLOPE FLOW HAS LED TO LIFR CONDITIONS AT SEVERAL SITES AND THIS WILL LIKELY CONTINUE THROUGHOUT THE AFTERNOON AND INTO THE EVENING. PRECIPITATION WILL BE MOST LIKELY AT KICT AND KCNU...WITH PERSISTENT LOW CLOUDS ELSEWHERE. WITH ASSOCIATED UPPER SYSTEM BEING SLOW TO MOVE OUT...CLEARING WILL BE VERY SLOW...WITH ONLY PARTIAL CLEARING AT NORTHWEST SITES ON TUE MORNING. -HOWERTON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 39 54 36 64 / 40 10 0 0 HUTCHINSON 34 55 36 63 / 20 10 0 0 NEWTON 37 54 36 63 / 30 10 0 10 ELDORADO 39 53 36 62 / 50 10 0 10 WINFIELD-KWLD 42 52 37 64 / 60 10 0 10 RUSSELL 32 55 30 64 / 10 10 0 0 GREAT BEND 32 55 32 64 / 10 10 0 0 SALINA 35 55 36 63 / 20 10 0 10 MCPHERSON 35 55 36 63 / 20 10 0 0 COFFEYVILLE 46 53 35 61 / 90 50 20 10 CHANUTE 44 51 35 60 / 90 40 20 10 IOLA 42 51 35 60 / 90 30 20 10 PARSONS-KPPF 45 52 35 61 / 90 50 20 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 702 PM CDT MON MAR 17 2008 .AVIATION... 00Z TAFS...ICT/SLN/HUT/CNU/RSL...LOW CLOUDS AND REDUCED VISIBILITIES SHOULD GRADUALLY IMPROVE LATE TONIGHT AND TUESDAY MORNING FROM NORTHWEST TO SOUTHEAST...AS LOW-LEVEL DRY AIR ADVECTION COMMENCES SLOWLY IN WAKE OF COLD FRONT CURRENTLY PROGRESSING ACROSS OKLAHOMA/SOUTHEAST KANSAS. HOWEVER...CONFIDENCE REMAINS LOW ON EXACTLY WHEN THE CIGS/VSBYS WILL BEGIN TO IMPROVE LATER TONIGHT...ALONG WITH HOW MUCH THEY`LL IMPROVE. WILL MAKE TIMELY AMENDMENTS WHEN/WHERE NECESSARY. ADDITIONALLY...NUMEROUS SHOWERS/THUNDERSTORMS ARE ANTICIPATED THROUGH THE OVERNIGHT HOURS ACROSS EASTERN OKLAHOMA...ARKANSAS AND MISSOURI...AS MOISTURE CONVERGENCE INCREASES ALONG PROGRESSING FRONT...IN COMBINATION WITH INCREASING LOW-LEVEL JET. SOME OF THIS ACTIVITY COULD CLIP FAR SOUTHEAST KANSAS THROUGH THE OVERNIGHT HOURS. KLEINSASSER && .PREV DISCUSSION... /ISSUED 321 PM CDT MON MAR 17 2008/ DISCUSSION... FORECAST CHALLENGES WILL BE PRECIP CHANCES AND ASSOCIATED FLOODING FOR THE FIRST COUPLE OF PERIODS. SYNOPSIS: IN THE UPPER LEVELS CURRENTLY HAVE A POWERFUL UPPER LOW SITUATED OVER THE DESERT SOUTHWEST WITH WATER VAPOR IMAGERY SHOWING A NICE SUBTROPICAL MOISTURE FETCH INTO THE CENTRAL PLAINS. AT THE SURFACE A LOW IS LOCATED OVER SW TX WITH A COLD FRONT/TROUGH STRETCHING FROM NORTHWEST MO THROUGH CENTRAL OK. TONIGHT-TUE: THE UPPER LOW TO OUR SOUTHWEST IS EXPECTED TO MEANDER VERY SLOWLY EAST THIS EVENING AS LOW LEVEL MOISTURE CONTINUES TO PUMP INTO THE SOUTHERN PLAINS. SHORT RANGE MODELS(INCLUDING RUC) ARE IN GOOD AGREEMENT REGARDING QPF LOCATION OVER THE NEXT 12 HOURS WHICH DOES LEAD TO SOME CONFIDENCE. MOISTURE TRANSPORT OFF OF THE 300K SURFACE WILL SHIFT EAST OVERNIGHT...PLACING THE HIGHEST PRECIP TOTALS AND FLOODING OVER SOUTHERN MO AND AR. SO NOT PLANNING ANY FLOOD WATCHES AT THIS TIME WITH THE THINKING THAT PRECIP OVER SE KS MAY CAUSE SOME MINOR FLOODING OF FLOOD PRONE AREAS AT BEST...WITH THE MORE SIGNIFICANT FLOODING OCCURRING TO OUR EAST. NOT TOO IMPRESSED WITH SEVERE POTENTIAL OVER THE NEXT SEVERAL HOURS. SINCE WE`VE STAYED GRUNGED-OUT WITH LOW CLOUDS AND SHOWERS/STORMS...INSTABILITY IS VERY LIMITED. IN ADDITION MODELS ARE NOT SHOWING MUCH ELEVATED INSTABILITY. THEREFORE CURRENT THINKING IS THAT SPEED SHEAR FROM 850MB-500MB MAYBE GOOD ENOUGH TO PRODUCE SOME DIME TO NICKLE SIZE HAIL OVER SE KS. BY TUE AFTERNOON THE UPPER LOW WILL BE SITUATED OVER EXTREME SW TX WITH THE SURFACE TROUGH/COLD FRONT EXTENDING FROM THE ARKLATEX REGION INTO THE OZARKS. IN THE UPPER LEVELS A STRONG JET WILL BE TRACKING OVER THE NORTHERN MISSISSIPPI VALLEY PLACING THE OZARK REGION IN THE RIGHT ENTRANCE REGION OF THIS JET WITH THE MODELS RESPONDING TO THIS BY BACKING THE 850MB FLOW WHICH SHOULD ENHANCE LOW LEVEL CONVERGENCE AND PRECIP COVERAGE TO OUR EAST. FOR OUR AREA ONLY EXTREME SE KS WILL HAVE A SHOT AT ADDITIONAL PRECIP WITH THE REMAINDER OF THE AREA STAYING DRY ON TUE. WED-THU: STRONG UPPER LOW WILL MOVE INTO THE SOUTHERN MISSISSIPPI VALLEY BY WED AFTERNOON AS ANOTHER MUCH WEAKER UPPER PIECE OF ENERGY TRACKS ACROSS THE NORTHERN PLAINS. THIS SET-UP WILL ALLOW THE FORECAST AREA TO DRY OUT. FOR THU THE UPPER PATTERN WILL FLATTEN ALLOWING ABOVE NORMAL TEMPS TO PREVAIL ACROSS THE AREA. FRI-MON: UPPER PATTERN WILL REMAIN FAIRLY ZONAL THROUGH SAT WITH BOTH THE ECMWF AND GFS SWINGING THROUGH A FAST MOVING PIECE OF ENERGY ACROSS THE NORTHERN PLAINS AND INTO MO BY SUN MORNING. THIS FEATURE MAY SPARK OFF SOME PRECIP SAT INTO SAT NIGHT WHICH THE PREVIOUS FORECAST ALREADY HAD IN. IN ADDITION BOTH THE ECMWF AND GFS ARE SPILLING SOME COOLER AIR INTO THE AREA FOR SAT AS THIS SYSTEM DEPARTS. WITH THIS WAVE WELL TO OUR EAST ON SUN...SURFACE HIGH WILL SLIDE-IN OVER THE CENTRAL PLAINS. THEREFORE WENT AHEAD TOOK PRECIP OUT OF FORECAST FOR SUN. WHILE CONFIDENCE IN PRECIP CHANCES ARE LOW FOR MON...AM FAIRLY CONFIDENT THAT THERE WILL BE SOME LEE TROUGHING AND ABOVE NORMAL TEMPS. LAWSON AVIATION... 18Z TAFS...MOIST UPSLOPE FLOW HAS LED TO LIFR CONDITIONS AT SEVERAL SITES AND THIS WILL LIKELY CONTINUE THROUGHOUT THE AFTERNOON AND INTO THE EVENING. PRECIPITATION WILL BE MOST LIKELY AT KICT AND KCNU...WITH PERSISTENT LOW CLOUDS ELSEWHERE. WITH ASSOCIATED UPPER SYSTEM BEING SLOW TO MOVE OUT...CLEARING WILL BE VERY SLOW...WITH ONLY PARTIAL CLEARING AT NORTHWEST SITES ON TUE MORNING. -HOWERTON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 39 54 36 64 / 20 10 0 0 HUTCHINSON 33 55 36 63 / 20 10 0 0 NEWTON 36 54 36 63 / 20 10 0 10 ELDORADO 38 53 36 62 / 40 10 0 10 WINFIELD-KWLD 43 52 37 64 / 40 10 0 10 RUSSELL 31 55 30 64 / 10 10 0 0 GREAT BEND 30 55 32 64 / 10 10 0 0 SALINA 35 55 36 63 / 20 10 0 10 MCPHERSON 34 55 36 63 / 20 10 0 0 COFFEYVILLE 47 53 35 61 / 90 50 20 10 CHANUTE 44 51 35 60 / 90 40 20 10 IOLA 42 51 35 60 / 90 30 20 10 PARSONS-KPPF 46 52 35 61 / 90 50 20 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 321 PM CDT MON MAR 17 2008 .DISCUSSION... FORECAST CHALLENGES WILL BE PRECIP CHANCES AND ASSOCIATED FLOODING FOR THE FIRST COUPLE OF PERIODS. SYNOPSIS: IN THE UPPER LEVELS CURRENTLY HAVE A POWERFUL UPPER LOW SITUATED OVER THE DESERT SOUTHWEST WITH WATER VAPOR IMAGERY SHOWING A NICE SUBTROPICAL MOISTURE FETCH INTO THE CENTRAL PLAINS. AT THE SURFACE A LOW IS LOCATED OVER SW TX WITH A COLD FRONT/TROUGH STRETCHING FROM NORTHWEST MO THROUGH CENTRAL OK. TONIGHT-TUE: THE UPPER LOW TO OUR SOUTHWEST IS EXPECTED TO MEANDER VERY SLOWLY EAST THIS EVENING AS LOW LEVEL MOISTURE CONTINUES TO PUMP INTO THE SOUTHERN PLAINS. SHORT RANGE MODELS(INCLUDING RUC) ARE IN GOOD AGREEMENT REGARDING QPF LOCATION OVER THE NEXT 12 HOURS WHICH DOES LEAD TO SOME CONFIDENCE. MOISTURE TRANSPORT OFF OF THE 300K SURFACE WILL SHIFT EAST OVERNIGHT...PLACING THE HIGHEST PRECIP TOTALS AND FLOODING OVER SOUTHERN MO AND AR. SO NOT PLANNING ANY FLOOD WATCHES AT THIS TIME WITH THE THINKING THAT PRECIP OVER SE KS MAY CAUSE SOME MINOR FLOODING OF FLOOD PRONE AREAS AT BEST...WITH THE MORE SIGNIFICANT FLOODING OCCURRING TO OUR EAST. NOT TOO IMPRESSED WITH SEVERE POTENTIAL OVER THE NEXT SEVERAL HOURS. SINCE WE`VE STAYED GRUNGED-OUT WITH LOW CLOUDS AND SHOWERS/STORMS...INSTABILITY IS VERY LIMITED. IN ADDITION MODELS ARE NOT SHOWING MUCH ELEVATED INSTABILITY. THEREFORE CURRENT THINKING IS THAT SPEED SHEAR FROM 850MB-500MB MAYBE GOOD ENOUGH TO PRODUCE SOME DIME TO NICKLE SIZE HAIL OVER SE KS. BY TUE AFTERNOON THE UPPER LOW WILL BE SITUATED OVER EXTREME SW TX WITH THE SURFACE TROUGH/COLD FRONT EXTENDING FROM THE ARKLATEX REGION INTO THE OZARKS. IN THE UPPER LEVELS A STRONG JET WILL BE TRACKING OVER THE NORTHERN MISSISSIPPI VALLEY PLACING THE OZARK REGION IN THE RIGHT ENTRANCE REGION OF THIS JET WITH THE MODELS RESPONDING TO THIS BY BACKING THE 850MB FLOW WHICH SHOULD ENHANCE LOW LEVEL CONVERGENCE AND PRECIP COVERAGE TO OUR EAST. FOR OUR AREA ONLY EXTREME SE KS WILL HAVE A SHOT AT ADDITIONAL PRECIP WITH THE REMAINDER OF THE AREA STAYING DRY ON TUE. WED-THU: STRONG UPPER LOW WILL MOVE INTO THE SOUTHERN MISSISSIPPI VALLEY BY WED AFTERNOON AS ANOTHER MUCH WEAKER UPPER PIECE OF ENERGY TRACKS ACROSS THE NORTHERN PLAINS. THIS SET-UP WILL ALLOW THE FORECAST AREA TO DRY OUT. FOR THU THE UPPER PATTERN WILL FLATTEN ALLOWING ABOVE NORMAL TEMPS TO PREVAIL ACROSS THE AREA. FRI-MON: UPPER PATTERN WILL REMAIN FAIRLY ZONAL THROUGH SAT WITH BOTH THE ECMWF AND GFS SWINGING THROUGH A FAST MOVING PIECE OF ENERGY ACROSS THE NORTHERN PLAINS AND INTO MO BY SUN MORNING. THIS FEATURE MAY SPARK OFF SOME PRECIP SAT INTO SAT NIGHT WHICH THE PREVIOUS FORECAST ALREADY HAD IN. IN ADDITION BOTH THE ECMWF AND GFS ARE SPILLING SOME COOLER AIR INTO THE AREA FOR SAT AS THIS SYSTEM DEPARTS. WITH THIS WAVE WELL TO OUR EAST ON SUN...SURFACE HIGH WILL SLIDE-IN OVER THE CENTRAL PLAINS. THEREFORE WENT AHEAD TOOK PRECIP OUT OF FORECAST FOR SUN. WHILE CONFIDENCE IN PRECIP CHANCES ARE LOW FOR MON...AM FAIRLY CONFIDENT THAT THERE WILL BE SOME LEE TROUGHING AND ABOVE NORMAL TEMPS. LAWSON && .AVIATION... MOIST UPSLOPE FLOW HAS LED TO IIFR CONDITION AT SEVERAL SITES AND THIS WILL LIKELY CONTINUE THROUGHOUT THE AFTERNOON AND INTO THE EVENING. PRECIPITATION WILL BE MOST LIKELY AT KICT AND KCNU...WITH PERSISTENT LOW CLOUDS ELSEWHERE. WITH ASSOCIATED UPPER SYSTEM BEING SLOW TO MOVE OUT...CLEARING WILL BE VERY SLOW...WITH ONLY PARTIAL CLEARING AT NORTHWEST SITES ON TUE MORNING. -HOWERTON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 39 54 36 64 / 20 10 0 0 HUTCHINSON 33 55 36 63 / 20 10 0 0 NEWTON 36 54 36 63 / 20 10 0 10 ELDORADO 38 53 36 62 / 40 10 0 10 WINFIELD-KWLD 43 52 37 64 / 40 10 0 10 RUSSELL 31 55 30 64 / 10 10 0 0 GREAT BEND 30 55 32 64 / 10 10 0 0 SALINA 35 55 36 63 / 20 10 0 10 MCPHERSON 34 55 36 63 / 20 10 0 0 COFFEYVILLE 47 53 35 61 / 90 50 20 10 CHANUTE 44 51 35 60 / 90 40 20 10 IOLA 42 51 35 60 / 90 30 20 10 PARSONS-KPPF 46 52 35 61 / 90 50 20 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1256 PM CDT MON MAR 17 2008 .UPDATE... UPDATED GRIDS A WHILE AGO AND WILL LIKELY UPDATE AGAIN IN THE NEXT HOUR. RUC AND 1200 UTC GLOBAL FORECAST SYSTEM MODEL SHOW PRECIPITATION VERY GRADUALLY SHIFTING INTO SOUTHEAST KS. APPEARS THAT SEVERE THREAT MAY BE DIMINISHING...BUT GLOBAL FORECAST SYSTEM MODEL FORECAST SOUNDINGS SUGGEST AROUND 700 ELEVATED CONVECTIVE AVAILABLE POTENTIAL ENERGY. SO FAR THIS MORNING...MID LEVEL WIND PROFILES HAVE NOT BE CONDUCIVE TO HAIL PRODUCTION...HOWEVER PROFILES AND GLOBAL FORECAST SYSTEM MODEL FORECASTS SEEM TO SUGGEST THIS MAY IMPROVE DURING THE AFTERNOON. WILL CONTINUE MENTION OF SEVERE THREAT IN HAZARDOUS WEATHER OUTLOOK...BUT WILL LIKELY TRIM AREA A BIT TO THE SOUTHEAST. PRIMARY THREAT MAY BE HEAVY RAIN. HOWEVER 1200 UTC MODELS SUGGEST LESS PRECIPITATION POTENTIAL WITH DECREASING BAROCLINICITY...WHICH IS SUPPORTED BY LATEST RADAR TRENDS. DO NOT ANTICIPATE HOISTING FLOOD WATCH AT THIS TIME. -HOWERTON && .AVIATION... MOIST UPSLOPE FLOW HAS LED TO IIFR CONDITION AT SEVERAL SITES AND THIS WILL LIKELY CONTINUE THROUGHOUT THE AFTERNOON AND INTO THE EVENING. PRECIPITATION WILL BE MOST LIKELY AT KICT AND KCNU...WITH PERSISTENT LOW CLOUDS ELSEWHERE. WITH ASSOCIATED UPPER SYSTEM BEING SLOW TO MOVE OUT...CLEARING WILL BE VERY SLOW...WITH ONLY PARTIAL CLEARING AT NORTHWEST SITES ON TUE MORNING. -HOWERTON && .PREV DISCUSSION... /ISSUED 605 AM CDT MON MAR 17 2008/ AVIATION... 12Z TAFS...THUNDERSTORMS ALREADY MOVING INTO SOUTHERN KANSAS THIS MORNING...AND WILL CONTINUE TO AFFECT ALL TAF SITES FOR MUCH OF THE DAY. CENTRAL KANSAS WILL SEE THUNDER END FIRST...BUT LIGHT RAIN OR DRIZZLE WILL CONTINUE THROUGH THE TAF PERIOD WITH IFR CEILINGS. HARD TO PINPOINT WHEN BEST THUNDER CHANCES WILL BE AT EACH SITE AS THREAT WILL EXIST FOR MUCH OF THE TAF PERIOD IN SOUTH CENTRAL AND SOUTHEAST KANSAS. SOME OF THE THUNDERSTORMS COULD CONTAIN STRONG WINDS AND LARGE HAIL ESPECIALLY IN SOUTH CENTRAL AND SOUTHEAST KANSAS. SCHRECK PREV DISCUSSION... /ISSUED 316 AM CDT MON MAR 17 2008/ DISCUSSION... FORECAST CONCERNS...CONVECTIVE TRENDS/SEVERE POTENTIAL TODAY AND PRECIP AMOUNTS THROUGH TUESDAY MORNING. UPPER LOW WAS SPINNING OVER AZ/NM EARLY THIS MORNING...WITH LEAD IMPULSE BEGINNING TO EJECT NORTHEAST ACROSS THE SOUTHERN HIGH PLAINS. STRONG LOW LEVEL JET WILL TRANSPORT ELEVATED MOISTURE NORTHWARD THRU THE MORNING ACROSS CENTRAL/EASTERN KANSAS RESULTING RAPID DESTABILIZATION OF AIRMASS ACROSS THE AREA. ELEVATED CAPE VALUES OF 700 TO 900 J/KG PROGGED BY THE GFS BY 12Z...WITH STRONG DEEP LAYER SHEAR. CONVECTION SHOULD CONTINUE TO BLOSSOM ACROSS NORTHWEST OKLAHOMA INTO CENTRAL KANSAS THRU 12Z...AND EXPAND QUICKLY EAST-NORTHEAST INTO SOUTHEAST KANSAS INTO MIDDAY. THE GIVEN SHEAR AND EXPECTED INSTABILITY WILL RESULT IN A FEW STRONG AND PERHAPS LOCALLY SEVERE STORMS...PERHAPS EVEN A BIT FURTHER NORTHWEST OF CURRENT SPC DAY 1 OUTLOOK AREA. BEST LIFT/FORCING TO SHIFT JUST NORTHEAST OF THE AREA DURING THE AFTERNOON...WITH RELATIVE DECREASE IN AREAL COVERAGE AND LIKEWISE POP FORECAST. PREVALENT CLOUD COVER WILL LIMIT DIURNAL HEATING ALONG/SOUTH OF DEVELOPMENTAL SURFACE FRONTAL BOUNDARY THIS AFTERNOON/EARLY EVENING...ACROSS SOUTHERN SECTIONS OF THE FORECAST AREA. HOWEVER...A FEW STRONG/ISOLATED SEVERE STORMS WILL REMAIN POSSIBLE. COUPLED UPPER JET STRUCTURE LATE TONIGHT/EARLY TUESDAY MORNING ACROSS THE AREA WILL RESULT IN RENEWED/INCREASE COVERAGE IN CONVECTION FROM EASTERN OKLAHOMA INTO SOUTHWEST MISSOURI...SOME OF WHICH MAY AFFECT THE SOUTHEAST CORNER OF KANSAS. MEANWHILE...DRIER NORTHERLY LOW LEVEL FLOW ACROSS CENTRAL KANSAS WILL RESULT IN SQUEEZE PLAY WITH DECREASING CHANCES FOR MEASURABLE PRECIP. THEREFORE WILL SHOW A TIGHTER POP GRADIENT ACROSS THE FORECAST AREA LATE TONIGHT...AND LIKEWISE QPF GRADIENT FOR SOUTHEAST KANSAS. MAIN UPPER LOW WILL MOVE EAST-NORTHEAST ACROSS THE SOUTHERN PLAINS ON TUESDAY...WITH PRECIP CHANCES LINGERING IN THE SOUTHEAST BUT ENDING FOR CENTRAL KANSAS. DRIER/MILDER WEATHER ON TAP FOR WEDNESDAY...WITH LITTLE CHANGE TO OUTER PERIODS OF THE FORECAST. DARMOFAL AVIATION... 06Z TAFS...ICT/SLN/HUT/CNU/RSL...BUSY 24 HOURS FOR AREA AIRPORT TERMINALS. STRONG LOW-MID LEVEL ISENTROPIC ASCENT AND ESPECIALLY MOISTURE TRANSPORT WILL MOVE INTO THE AREA LATER TONIGHT...PER 50KT SOUTHERLY LOW-LEVEL JET. ATTENDANT ELEVATED INSTABILITY SHOULD INCREASE ENOUGH FOR SCATTERED TO NUMEROUS THUNDERSTORMS TO BREAK OUT AFTER 09-10Z (4-5AM) FROM SOUTH TO NORTH ACROSS THE AREA. AMPLE CLOUD-BEARING SHEAR MAY RESULT IN STRONG TO MARGINALLY SEVERE STORMS WITH DIME TO QUARTER SIZED HAIL THE PRIMARY THREAT. INCREASING LOW-LEVEL MOISTURE ALONG WITH PERSISTENT UPSLOPE FLOW WILL ALLOW CIGS TO EVENTUALLY FALL TO MVFR TO IFR CATEGORIES...LOWEST OVER THE WESTERN HALF OF KANSAS...AND PERSIST THROUGH MUCH OF MONDAY WITH AREAS OF PRECIPITATION SHIFTING EAST THROUGH THE DAY. KLEINSASSER && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 50 40 54 34 / 100 60 30 0 HUTCHINSON 44 34 53 32 / 100 50 20 0 NEWTON 46 36 52 32 / 100 60 20 0 ELDORADO 51 39 52 33 / 100 70 30 0 WINFIELD-KWLD 55 42 54 35 / 100 70 40 0 RUSSELL 41 30 54 28 / 100 30 10 0 GREAT BEND 42 32 54 30 / 100 30 10 0 SALINA 45 34 54 31 / 100 40 10 0 MCPHERSON 44 34 53 31 / 100 50 20 0 COFFEYVILLE 64 48 55 37 / 100 90 60 10 CHANUTE 58 43 53 34 / 100 90 60 10 IOLA 57 43 53 34 / 100 90 60 10 PARSONS-KPPF 61 46 54 36 / 100 90 60 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1145 AM MDT MON MAR 17 2008 .UPDATE... 1004 AM MDT MON MAR 17 2008 MOST OF THE PRECIPITATION HAS DROPPED OFF ACROSS THE AREA THIS MORNING DECREASING THE THREAT OF ADDITIONAL ACCUMULATIONS. HAVE CANCELLED ALL THE HIGHLIGHTS FOR THE FA AND UPDATED POPS AND WEATHER TO REFLECT THE CURRENT TRENDS. LEFT A CHC -SN AND PATCHY FRZG DRIZZLE OVER THE NORTHWEST PORTION OF THE TRI-STATE AREA WITH CHC -RA AND FOG ELSEWHERE. .DISCUSSION... 234 AM MDT MON MAR 17 2008 MAIN FORECAST PROBLEM WILL PRECIPITATION AMOUNTS AND PHASE THROUGH THE DAY. SECONDARY PROBLEM WILL BE THE AMOUNT OF WARMUP INTO WEDNESDAY WHICH WILL BE INFLUENCED BY THE EXTENT AND DEPTH OF THE SNOWFIELD. SATELLITE SHOWING A PROGRESSIVE BUT SOMEWHAT AMPLIFIED PATTERN FROM THE CENTRAL PACIFIC INTO THE WESTERN ATLANTIC. EXCEPTION TO THIS FLOW AND THE MAIN FEATURE OF INTEREST IS CUTOFF LOW OVER THE SOUTHERN GREAT BASIN THAT IS ONLY MOVING SLOWLY SOUTH AND EAST AT THIS TIME. THE NORTHERN CIRCULATION CENTER IS OVER NORTHEAST ARIZONA WITH THE TROUGH HANGING BACK TO THE SOUTHWEST. AT JET LEVEL...MODELS INITIALIZED WELL ON THE JET FROM THE PACIFIC INTO OUR AREA. VERY STRONG JET...150 TO 160 KNOTS...PUSHING INTO THE AREA. JET WINDS ARE STRONG ON THE WEST SIDE OF INCOMING UPPER TROUGH BUT ARE SLIGHTLY LOWER THAN ON THE EAST SIDE. WOULD GIVE THE EDGE TO THE NAM/GFS...ESPECIALLY ON THE SEGMENT OF THE JET BEHIND THE TROUGH. AT MID LEVELS...THE GFS/RUC WERE DOING SLIGHTLY BETTER THAN THE ECWMF/UKMET. AT LOW LEVELS...MODELS WERE HAVING THEIR PROBLEMS WITH THE THERMAL FIELD TO OUR SOUTH...AND ALSO WERE A LITTLE WARM WITH THE AIR MASS TO OUR NORTHWEST. THE GFS/UKMET LOOKED TO BE DOING A LITTLE BETTER WITH THE WIND FIELD. RIGHT THE GFS FORCING AND INSTABILITY AND EVEN PRECIPITATION FIELD ...EVEN THOUGH THE QPF AMOUNTS ARE OVERDONE...ARE MATCHING UP WELL WITH RADAR/SATELLITE/SURFACE OBSERVATIONS RIGHT NOW. THE GFS WITH SOME SUPPORT FROM THE SREF/HPC PRECIPITATION...SUPPORTS CURRENT PRECIPITATION FORECAST/HIGHLIGHTS WELL. WILL BE BLENDING THE GFS WITH REALITY FOR THE INITIALLY PORTION OF THE FORECAST AND THEN WILL GO WITH A BLEND OF MODEL OUTPUT...MAINLY GFS/UKMET...FOR THE REMAINDER OF THE FORECAST. TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET IS OVER THE AREA THROUGH THE EARLY AFTERNOON BEFORE PUSHING TO THE EAST. THE GFS IS A LITTLE FURTHER EAST THAN THE NAM. AS STATED ABOVE...GFS SUPPORTING CURRENT FORECAST. FORCING/LIFT/INSTABILITY PROGS SHOW BEST PARAMETERS CORRESPONDING TO THE WARNING AREA. SHOULD BE GETTING A GOOD BURST OF PRECIPITATION FROM NOW UNTIL THE MIDDLE OF THE MORNING. FROM LATE MORNING ON...WEAKER MESOSCALE AND STRONGER SYNOPTIC LIFT PREVAIL. HOWEVER...POINT SOUNDINGS SHOW THE AIR MASS DRYING OUT ABOVE 700 MB. THE BEST MOISTURE AND LIFT RESIDE IN THE NORTHWEST PORTION OF THE AREA AFTER 18Z. WILL PROBABLY KEEP A MENTION OF MEASURABLE THERE WITH AREAS OF DRIZZLE OR FREEZING DRIZZLE OVER THE REMAINDER OF THE AREA. CONCERNING THE HIGHLIGHT...IT MAY BE A LITTLE LONG. HOWEVER...DUE TO ENOUGH UNCERTAINTY...POOR MODEL PERFORMANCE...AND CURRENT RADAR TRENDS...WILL LEAVE IT OUT THROUGH 00Z. WOULD RATHER HAVE IT GO TOO LONG THAN NOT LONG ENOUGH. WILL MONTIOR TRENDS FOR NEAR RED WILLOW COUNTY. IF SNOW PICKS UP MORE...MAY UPGRADE THEM LATER TO A WARNING. DID NOT SPEND A LOT OF TIME ON TEMPERATURES. HOWEVER...GOING NEAR THE SIMILAR GUIDANCE LOOKS REASONABLE. TUESDAY/TUESDAY NIGHT...LOOK TO HAVE PLENT OF SUN. HOWEVER...UPPER TROUGH AND JET AXIS STILL TO THE WEST OF US. ALSO WIND WILL BE BLOWING OFF OF SNOW FIELD TO OUR NORTHWEST. WILL PROBABLY END UP GOING NEAR TO SLIGHTLY BELOW GUIDANCE NEAR AND IN THE EXPECTED SNOW FIELD. CAN SEE WHERE THE NAM HAS THE SNOW FIELD WITH THE COLD 2 METER TEMPERATURES FOR THE DAY. IT LOOKS LIKE IT IS OVERDOING IT. WEDNESDAY/WEDNESDAY NIGHT...JET MOVES EAST DURING THE DAY AS THE RIDGE BUILDS IN. THE GFS/MAV REALLY WARMS UP THE MAXES WITH NAM HOLDING ONTO THE COLDER TEMPERATURES. THAT MAY BE CORRECT IN THE DEEPER SNOW COVER BUT BELIEVE IT IS OVERDOING THE COVERAGE OF THE COLDER TEMPERATURES. WILL HAVE PLENTY OF SUN AND DOWNSLOPE WINDS WHICH MAY BRING SOME COOLER OFF THE SNOW FIELD. WILL PLAY FOR SLIGHTLY COOLER TEMPERATURES IN THE NORTHWEST HALF AND WARMER TEMPERATURES IN THE SOUTHEAST HALF. THANKS TO ALL FOR COLLABORATION. BULLER && .AVIATION... 1145 MDT MAR 17 2008 FOR THE 12Z TAFS... LIFR/IFR CONDITIONS REMAIN OVER THE TAF SITES AS CEILINGS CONTINUE TO HOVER BETWEEN 300-500 FT WITH VIS AROUND 3SM. WILL SEE IMPROVEMENT WITH THE AFTERNOON HOURS AS BOTH CIGS AND VIS IMPROVE TO MVFR THROUGH 00Z AND THEN AFTER 06Z TO VFR. MOST OF THE PRECIPITATION MOVED TO THE NORTHEAST OF THE TAF SITES THIS MORNING...BUT AM SEEING SOME ENHANCED CLOUD COVER THE KS/CO BORDER JUXTAPOSED WITH SOME LIGHT RADAR RETURNS. MAY SEE SOME FLURRIES THROUGH THE AFTERNOON HOURS. KTB && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ 99/99 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 538 AM MDT MON MAR 17 2008 .DISCUSSION... 234 AM MDT MON MAR 17 2008 MAIN FORECAST PROBLEM WILL PRECIPITATION AMOUNTS AND PHASE THROUGH THE DAY. SECONDARY PROBLEM WILL BE THE AMOUNT OF WARMUP INTO WEDNESDAY WHICH WILL BE INFLUENCED BY THE EXTENT AND DEPTH OF THE SNOWFIELD. SATELLITE SHOWING A PROGRESSIVE BUT SOMEWHAT AMPLIFIED PATTERN FROM THE CENTRAL PACIFIC INTO THE WESTERN ATLANTIC. EXCEPTION TO THIS FLOW AND THE MAIN FEATURE OF INTEREST IS CUTOFF LOW OVER THE SOUTHERN GREAT BASIN THAT IS ONLY MOVING SLOWLY SOUTH AND EAST AT THIS TIME. THE NORTHERN CIRCULATION CENTER IS OVER NORTHEAST ARIZONA WITH THE TROUGH HANGING BACK TO THE SOUTHWEST. AT JET LEVEL...MODELS INITIALIZED WELL ON THE JET FROM THE PACIFIC INTO OUR AREA. VERY STRONG JET...150 TO 160 KNOTS...PUSHING INTO THE AREA. JET WINDS ARE STRONG ON THE WEST SIDE OF INCOMING UPPER TROUGH BUT ARE SLIGHTLY LOWER THAN ON THE EAST SIDE. WOULD GIVE THE EDGE TO THE NAM/GFS...ESPECIALLY ON THE SEGMENT OF THE JET BEHIND THE TROUGH. AT MID LEVELS...THE GFS/RUC WERE DOING SLIGHTLY BETTER THAN THE ECWMF/UKMET. AT LOW LEVELS...MODELS WERE HAVING THEIR PROBLEMS WITH THE THERMAL FIELD TO OUR SOUTH...AND ALSO WERE A LITTLE WARM WITH THE AIR MASS TO OUR NORTHWEST. THE GFS/UKMET LOOKED TO BE DOING A LITTLE BETTER WITH THE WIND FIELD. RIGHT THE GFS FORCING AND INSTABILITY AND EVEN PRECIPITATION FIELD ...EVEN THOUGH THE QPF AMOUNTS ARE OVERDONE...ARE MATCHING UP WELL WITH RADAR/SATELLITE/SURFACE OBSERVATIONS RIGHT NOW. THE GFS WITH SOME SUPPORT FROM THE SREF/HPC PRECIPITATION...SUPPORTS CURRENT PRECIPITATION FORECAST/HIGHLIGHTS WELL. WILL BE BLENDING THE GFS WITH REALITY FOR THE INITIALLY PORTION OF THE FORECAST AND THEN WILL GO WITH A BLEND OF MODEL OUTPUT...MAINLY GFS/UKMET...FOR THE REMAINDER OF THE FORECAST. TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET IS OVER THE AREA THROUGH THE EARLY AFTERNOON BEFORE PUSHING TO THE EAST. THE GFS IS A LITTLE FURTHER EAST THAN THE NAM. AS STATED ABOVE...GFS SUPPORTING CURRENT FORECAST. FORCING/LIFT/INSTABILITY PROGS SHOW BEST PARAMETERS CORRESPONDING TO THE WARNING AREA. SHOULD BE GETTING A GOOD BURST OF PRECIPITATION FROM NOW UNTIL THE MIDDLE OF THE MORNING. FROM LATE MORNING ON...WEAKER MESOSCALE AND STRONGER SYNOPTIC LIFT PREVAIL. HOWEVER...POINT SOUNDINGS SHOW THE AIR MASS DRYING OUT ABOVE 700 MB. THE BEST MOISTURE AND LIFT RESIDE IN THE NORTHWEST PORTION OF THE AREA AFTER 18Z. WILL PROBABLY KEEP A MENTION OF MEASURABLE THERE WITH AREAS OF DRIZZLE OR FREEZING DRIZZLE OVER THE REMAINDER OF THE AREA. CONCERNING THE HIGHLIGHT...IT MAY BE A LITTLE LONG. HOWEVER...DUE TO ENOUGH UNCERTAINTY...POOR MODEL PERFORMANCE...AND CURRENT RADAR TRENDS...WILL LEAVE IT OUT THROUGH 00Z. WOULD RATHER HAVE IT GO TOO LONG THAN NOT LONG ENOUGH. WILL MONTIOR TRENDS FOR NEAR RED WILLOW COUNTY. IF SNOW PICKS UP MORE...MAY UPGRADE THEM LATER TO A WARNING. DID NOT SPEND A LOT OF TIME ON TEMPERATURES. HOWEVER...GOING NEAR THE SIMILAR GUIDANCE LOOKS REASONABLE. TUESDAY/TUESDAY NIGHT...LOOK TO HAVE PLENT OF SUN. HOWEVER...UPPER TROUGH AND JET AXIS STILL TO THE WEST OF US. ALSO WIND WILL BE BLOWING OFF OF SNOW FIELD TO OUR NORTHWEST. WILL PROBABLY END UP GOING NEAR TO SLIGHTLY BELOW GUIDANCE NEAR AND IN THE EXPECTED SNOW FIELD. CAN SEE WHERE THE NAM HAS THE SNOW FIELD WITH THE COLD 2 METER TEMPERATURES FOR THE DAY. IT LOOKS LIKE IT IS OVERDOING IT. WEDNESDAY/WEDNESDAY NIGHT...JET MOVES EAST DURING THE DAY AS THE RIDGE BUILDS IN. THE GFS/MAV REALLY WARMS UP THE MAXES WITH NAM HOLDING ONTO THE COLDER TEMPERATURES. THAT MAY BE CORRECT IN THE DEEPER SNOW COVER BUT BELIEVE IT IS OVERDOING THE COVERAGE OF THE COLDER TEMPERATURES. WILL HAVE PLENTY OF SUN AND DOWNSLOPE WINDS WHICH MAY BRING SOME COOLER OFF THE SNOW FIELD. WILL PLAY FOR SLIGHTLY COOLER TEMPERATURES IN THE NORTHWEST HALF AND WARMER TEMPERATURES IN THE SOUTHEAST HALF. THANKS TO ALL FOR COLLABORATION. BULLER && .AVIATION... 538 AM MDT MON MAR 17 2008 FOR THE 12Z TAFS...ONGOING WINTER WX PRIMARY CONCERN AS FAIRLY COMPLICATED SCENARIO ONGOING ACROSS THE CWA THIS MORNING. BACK EDGE OF PRECIPITATION APPEARS TO BE TIED TO AREA OF FRONTOGENESIS AROUND H65. THIS AREA HOVERS AROUND KGLD AREA THROUGH THE MORNING BEFORE RETREATING TO THE WEST AS NEXT SHORT WAVE TROUGH MOVES OVER THE AREA THIS AFTERNOON. WATER VAPOR IMAGERY CONFRIMS MODEL FORECASTS OF DRY SLOT MOVING INTO THE AREA...BUT FORECAST SOUNDINGS...ALONG WITH CURRENT RADAR PRODUCTS SEEM TO INDICATE THAT THIS FEATURE IS FURTHER DESTABILIZING THINGS RATHER THAN DECREASING PRECIPITATION. HIGHEST PROBALILTY OF IFR/LIFR CONDTIONS WILL BE BEFORE 16Z AS LLJ AND AFFORMENTIONED FORCING BEGIN TO WEAKEN AFTER THAT. LESS CONFIDENT ABOUT PRECIPITATION REDEVELOPING DURING THE AFTERNOON...AND AT THIS POINT WILL JUST KEEP MVFR/IFR CONDTIONS THROUGH THE AFTERNOON AS PROFILES WOULD SUPPORT PERIODS OF -FZDZ THROUGH THE DAY. JRM && .GLD WATCHES/WARNINGS/ADVISORIES... KS...WINTER WEATHER ADVISORY UNTIL 6 PM MDT /7 PM CDT/ THIS AFTERNOON FOR KSZ003-015-028-041. WINTER STORM WARNING UNTIL 6 PM MDT /7 PM CDT/ THIS AFTERNOON FOR KSZ001-002-013-014-027. NE...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NEZ081. WINTER STORM WARNING UNTIL 6 PM MDT /7 PM CDT/ THIS AFTERNOON FOR NEZ079-080. CO...WINTER STORM WARNING UNTIL 6 PM MDT THIS AFTERNOON FOR COZ090>092. && $$ WFO GOODLAND ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1204 AM CDT MON MAR 17 2008 .AVIATION... 06Z TAFS...ICT/SLN/HUT/CNU/RSL...BUSY 24 HOURS FOR AREA AIRPORT TERMINALS. STRONG LOW-MID LEVEL ISENTROPIC ASCENT AND ESPECIALLY MOISTURE TRANSPORT WILL MOVE INTO THE AREA LATER TONIGHT...PER 50KT SOUTHERLY LOW-LEVEL JET. ATTENDANT ELEVATED INSTABILITY SHOULD INCREASE ENOUGH FOR SCATTERED TO NUMEROUS THUNDERSTORMS TO BREAK OUT AFTER 09-10Z (4-5AM) FROM SOUTH TO NORTH ACROSS THE AREA. AMPLE CLOUD-BEARING SHEAR MAY RESULT IN STRONG TO MARGINALLY SEVERE STORMS WITH DIME TO QUARTER SIZED HAIL THE PRIMARY THREAT. INCREASING LOW-LEVEL MOISTURE ALONG WITH PERSISTENT UPSLOPE FLOW WILL ALLOW CIGS TO EVENTUALLY FALL TO MVFR TO IFR CATEGORIES...LOWEST OVER THE WESTERN HALF OF KANSAS...AND PERSIST THROUGH MUCH OF MONDAY WITH AREAS OF PRECIPITATION SHIFTING EAST THROUGH THE DAY. KLEINSASSER && .PREV DISCUSSION... /ISSUED 932 PM CDT SUN MAR 16 2008/ UPDATE... 00Z RAOBS OUT OF OUN AND FWD INDICATE MODELS ARE OVERDOING 850MB MOISTURE BY A FEW DEGREES. THIS IN COMBINATION WITH THE LATEST RUC MODEL SOLUTION MAKES ME BELIEVE THE MARGINAL SEVERE THUNDERSTORM THREAT FOR LATE TONIGHT HAS DECREASED JUST A TAD AND SHIFTED SOUTH OVER THE FORECAST AREA. HOWEVER...WITH STRONG LOW-LEVEL JET CONTINUING TO TRANSPORT COPIOUS AMOUNTS OF MOISTURE NORTHWARD AS THE NIGHT PROGRESSES...STILL THINKING ELEVATED INSTABILITY ROOTED AROUND 800-750MB WILL RANGE FROM 500-1000 J/KG BY LATE TONIGHT ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA. THROW IN EXPECTED AMPLE CLOUD BEARING SHEAR...AM STILL THINKING STRONG TO MARGINALLY SEVERE ELEVATED STORMS WILL BE POSSIBLE AFTER 4 AM ACROSS PRIMARILY SOUTHERN PORTIONS OF THE FORECAST AREA. PRIMARY THREAT WILL BE DIME TO QUARTER SIZED HAIL. KLEINSASSER PREV DISCUSSION... /ISSUED 707 PM CDT SUN MAR 16 2008/ AVIATION... 00Z TAFS...ICT/SLN/HUT/CNU/RSL...BUSY 24 HOURS ANTICIPATED OVER CENTRAL...SOUTH-CENTRAL AND SOUTHEAST KANSAS. STRONG LOW-MID LEVEL ISENTROPIC ASCENT AND MOISTURE TRANSPORT WILL MOVE NORTH TONIGHT...INCREASING INSTABILITY AND LIFT. LEADING EDGE OF DEEPER LOW-LEVEL MOISTURE...ROOTED AROUND 800-750MB...HAS ALREADY SURGED AS FAR NORTH AS CENTRAL OKLAHOMA PER STRATOCUMULUS VIA SATELLITE IMAGERY/ASOS SITES. THIS SHOULD ALLOW SCATTERED TO NUMEROUS SHOWERS/THUNDERSTORMS TO BREAK OUT BY 07-10Z (2-5AM) FROM SOUTHWEST TO NORTHEAST ACROSS THE AREA. ELEVATED INSTABILITY AND CLOUD BEARING SHEAR WILL BE SUFFICIENT FOR STRONG TO SEVERE STORMS...WITH HAIL UP TO QUARTER SIZE THE PRIMARY THREAT. ADDITIONALLY...THE COMBINATION OF CONTINUED UPSLOPE FLOW AND LOW-LEVEL MOISTURE TRANSPORT WILL ALLOW CIGS TO DROP BELOW 2000 FT AGL BY 05-08Z (MIDNIGHT-2AM)...LOWEST FOR RSL TAF WHERE UPSLOPE FLOW WILL BE STRONGEST. OFF AND ON SHOWERS/THUNDERSTORMS SHOULD CONTINUE FOR MOST AREAS THROUGH AT LEAST MONDAY MORNING...AS BEST LOW/MID-LEVEL ISENTROPIC ASCENT/MOISTURE TRANSPORT PUSHES SLOWLY EAST. MVFR TO IFR CIGS SHOULD CONTINUE AS WELL. WILL MAKE TIMELY AMENDMENTS WHEN/WHERE NECESSARY. KLEINSASSER PREV DISCUSSION... /ISSUED 330 PM CDT SUN MAR 16 2008/ DISCUSSION... TONIGHT-TUE NIGHT: VERY ACTIVE WEATHER SLATED FOR ALL AREAS FROM LATE TONIGHT THRU EARLY TUE...ESPECIALLY IN SE KS. SYNOPTIC PATTERN CONTINUES TO EVOLVE AS ANTICIPATED OVER PAST 2 DAYS...WITH VERY INTENSE UPPER- DECK TROF SITUATED OVER WRN U.S. PROGRESSING EVER SO SLOWLY E TOWARD ROCKIES. VERY DEEP UPPER LOW STILL EXPECTED TO FORM OVER WRN RIO GRANDE MON NIGHT THAT WILL INDUCE STRONG N/NE SFC-850MB MOISTURE SURGE THAT`LL TARGET SE KS MON & MON NIGHT. IN ADDITION...THE INCREASING & GRADUALLY VEERING LOWER-DECK FLOW WILL PROMOTE WARM FRONTOGENESIS FROM SFC LOW...PROGGED TO BE POSITIONED OVER TX PANHANDLE MON MORNING...NE ACROSS FAR SC TO SE KS. THE FRONT MAY LIFT TO ALMOST THE I-70 CORRIDOR MON AFTERNOON AT WHICH TIME IT`LL PIVOT & SURGE SE AS COLD FRONT MON EVENING. THE DEEP- LAYER SHEAR OVER SC & SE KS...ESPECIALLY THE DIRECTIONAL VARIANT...WILL BE IMPRESSIVE. THEREFORE TSRA OCCURRING OVER SE KS MON AFTERNOON & MON EVENING MAY BE SEVERE WITH LARGE HAIL THE PRIMARY THREAT. PRECIPITABLE WATERS OVER SC & SE KS INCREASE GREATLY TO 1.25 TO 1.33 INCHES ON MON...& WHEN COUPLED WITH GRADUALLY INCREASING DEEP LAYER LIFT...VERY HEAVY RAINS ARE A VIRTUAL CERTAINTY. CHECKED SWING ON ISSUANCE OF A FLOOD/FLASH FLOOD WATCH FOR SE KS AS IT APPEARS LOWER DECK MOISTURE AXIS WILL BE SHUNTING SE OF THIS AREA LATE MON NIGHT. AS SUCH EXPECT GREATEST POTENTIAL FOR FLOOD/FLASH FLOOD PRODUCING RAINFALL TO TARGET THE SERN PLAINS FROM THE ARKLATEX REGION NE ACROSS SRN/CENTRAL MO. REGARDLESS...THE BEHAVIOR OF SE KS RIVERS SUCH AS THE NEOSHO WILL REQUIRE CLOSE MONITORING LATE MON NIGHT & TUE. WED-FRI: QUIET WEATHER SLATED ALL AREAS AS VERY INTENSE MID-UPPER TROF SURGES ACROSS LOWER MS VALLEY WED MORNING LEAVING ZONAL FLOW REGIME IN IT`S WAKE. TEMPERATURES TO RUN 5-7F ABOVE NORMAL IN MOST CASES. NEXT WEEKEND: THE NEXT CHANCE FOR RA/TSRA APPEARS TICKETED FOR THE REGION NEXT SAT & SUNDAY. A MID-UPPER DECK TROF WILL STRENGTHEN FRI NIGHT AS IT MOVES SE FROM THE NRN ROCKIES TO THE NRN/CENTRAL PLAINS...THEREBY INDUCING SFC-850MB LOW TO DEVELOP OVER W TX/TX PANHANDLE FRI NIGHT & SAT. SFC TO 850-MB COLD FRONTOGENESIS ENSUES EARLY SAT WITH THE SW-NE ORIENTED BOUNDARY EXTENDING FROM THE LOW ACROSS C/SC KS TO NRN MO ~12NOON SAT. AS THE UPPER TROF DIGS SE OVER THE SRN PLAINS...THE COLD FRONT WILL LIKEWISE SURGE SE ACROSS SE KS SAT AFTERNOON & EVENING THAT SHOULD ENCOURAGE INCREASED ISENTROPIC ASCENT. BEING A DAYS 6-7 FORECAST WILL ASSIGN GENERIC ~30% TO MOST AREAS AND LOWER SAT`S HIGHS ACROSS C KS TO LOWER 50S. EPS && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 45 59 38 54 / 70 100 60 30 HUTCHINSON 42 56 35 55 / 70 100 40 20 NEWTON 43 57 37 52 / 70 100 60 30 ELDORADO 43 59 39 52 / 70 100 60 30 WINFIELD-KWLD 46 61 41 55 / 70 100 70 40 RUSSELL 38 45 30 53 / 70 90 30 20 GREAT BEND 39 48 31 54 / 70 100 30 20 SALINA 39 52 33 53 / 70 100 40 20 MCPHERSON 41 54 34 53 / 70 100 40 20 COFFEYVILLE 46 63 46 55 / 60 100 80 50 CHANUTE 43 61 44 53 / 60 100 80 50 IOLA 43 61 43 52 / 60 100 80 50 PARSONS-KPPF 45 62 45 54 / 60 100 80 50 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1057 PM EDT TUE MAR 18 2008 .UPDATE... UPDATED FCST TO DROP MENTION OF ISOLD -SHSN/FZDZ LATE TONIGHT INTO THE EARLY MORNING FOR WRN UPPER MI AS DRIER AIR WILL BE SPREADING INTO THE AREA PER SATELLITE IMAGERY. BEFORE THEN...THERE STILL APPEARS TO BE SOME POTENTIAL FOR -FZDZ/FLURRIES FOR THE NEXT SEVERAL HOURS AS NARROW BAND OF SLIGHTLY HIGHER SFC DWPTS OVER EXTREME NE MN MOVES E AND UPSLOPES INTO WRN UPPER MI ON W TO NW WINDS. IN ADDITION...THERE HAVE BEEN A FEW OBS IN NE MN EARLIER THIS EVENING THAT INDICATED -DZ/-SN...AND KDLH RADAR HAS SHOWN SOME WEAK RETURNS. && .PREV DISCUSSION... (ISSUED AT 355 PM EDT) SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW ACRS NAMERICA WITH NRN BRANCH TROFFING DOMINATING THE UP GRT LKS. DISTURBANCE EMBEDDED WITHIN THIS FLOW THAT WAS RESPONSIBLE FOR THE SN THAT FELL EARLIER IN THE DAY IS NOW HEADING ENEWD THRU ERN UPR MI. ACCOMPANYING PCPN HAS PRETTY MUCH ENDED WITH ARRIVAL OF DRIER AIR ALF (IN THE LYR COLDER THAN -10C) THAT WAS SHOWN ON THE 12Z MPX SNDG. BUT PLENTY OF LO CLD REMAINS WITH AMPLE LLVL MSTR LINGERING. THE HIER LLVL DWPTS (GENERALLY 30 TO 35) AND IFR/MVFR CIGS EXTEND WWD THRU MOST OF MN TO NEAR REINFORCING COLD FNT NOW MOVING INTO NW MN. SOME LGT PCPN HAS BEEN OBSVD ALG AND JUST AHD OF THIS BNDRY. BUT DRIER AIR IS NOTED MOVING IN BEHIND THE COLD FNT. THE CORE OF THE COLDER AIR IS LOCATED A BIT FARTHER N...WITH 12Z H85 TEMP AT YQD DOWN TO -11C...VS -5C OBSVD AT INL. SHORT TERM DISCUSSION (TNGT AND WED)... MAIN FCST CONCERNS TNGT/TMRW ARE LGT PCPN CHCS/TYPE. NUMERICAL GUIDANCE HINTS COLD FNT NOW MOVING THRU MN WL MOVE INTO THE WRN ZNS ARND 06Z. WITH ABUNDANT LLVL MSTR NOTED AHEAD OF THIS BNDRY...MAINTAINED QUITE A BIT OF CLD COVER INTO THE OVERNGT AS WELL AS SOME PTCHY -DZ/-FZDZ/-SN ACRS MAINLY THE WRN ZNS WHERE LGT WLY FLOW WL UPSLOPE. ALSO INTRODUCED SOME LO CHC POPS FOR SIMILAR PCPN TYPE OVER THE ERN ZNS DOWNSTREAM OF LK SUP LATE TNGT WITH BETTER LLVL CNVGC ASSOCIATED WITH THE ARRIVAL OF THIS BNDRY. BUT INFLUX OF DRIER AIR LATE TNGT WL AT LEAST END THE POTENTIAL FOR -FZDZ OVER THE W AND BEGIN TO BREAK UP THE PERSISTENT CLD COVER IN THE DOWNSLOPE AREAS. IN ANY EVENT...LIMITED MOISTURE DEPTH AND MODEST CHILL (TEMPS WITHIN THE MOIST LYR FCST TO BE HIER THAN -10C) WL LIMIT PCPN COVG AND INTENSITY. TENDED TOWARD A BLEND OF ETA/GFS MOS GUIDANCE FOR MIN TEMPS FCST...WITH THE LOWER READINGS OVER THE W WITH MORE VIGOROUS LLVL DRYING LATE. ON WED...AN INCRSG N TO NW FLOW WL ADVECT COLDER AIR NOW OVER SCNTRL CAN INTO THE UPR GRT LKS. DURING MID WINTER...WOULD HAVE TO CONSIDER LES HEADLINES...BUT TIMING OF ARRIVAL OF COLDER AIR DURING THE DIURNAL HTG TIME AS WELL AS ACYC NATURE OF LARGER SCALE FLOW WL LIMIT LES BAND DVLPMNT/COVG/INTENSITY. ALTHOUGH FCST SHARP INVRN ARND H85 OR SO WL RESULT IN INCRSG SC DVLPMNT WITH THE DIURNAL HTG... THIS LO INVRN SHOULD LIMIT THE POTENTIAL FOR ANY INSTABILTY SHSN THAT MIGHT OTRW DVLP WELL INLAND WITH SFC HTG/INFLUX OF LLVL MSTR OFF THE LK. MIXING TO H85-825 ON GFS FCST SDNGS YIELDS HI TEMPS ARND 40 OVER THE SCNTRL...WHICH WL BE WARMEST WITH DOWNSLOPING NNW FLOW. LONG TERM DISCUSSION (WEDNESDAY NIGHT THROUGH NEXT TUESDAY)... TROUGHING IN THE GREAT LAKES TO BEGIN THE PERIOD GRADUALLY GETS REPLACED BY FLATTER FLOW ALOFT. AS TROUGH RUNS INTO STRONG RIDGE OVR NORTH ATLANTIC/GREENLAND EXPECT IT TO STALL THIS WEEKEND WHEN IT REACHES NORTHERN NEW ENGLAND/EASTERN CANADA. USUALLY THIS PATTERN RESULTS IN A COLDER PATTERN FOR GREAT LAKES/MID ATLANTIC AND THIS TIME IS NO EXCEPTION. AT THE LEAST...EXPECT BLO NORMAL TEMPS THROUGH THE WEEKEND. ALSO...WITH H85 TEMPS TOWARD -12C COULD END UP WITH LIGHT LK EFFECT SNOW SHOWERS. DUE TO ONSHORE FLOW AND AT LEAST WEAK OVER WATER INSTABILITY...WENT AHEAD AND LINGERED SNOW SHOWERS INTO FRIDAY NEAR LK SUPERIOR. BEST CHANCE FOR A PERIOD OF SOME ACCUMULATION WOULD BE LATE WED NIGHT INTO THU WITH ADDITIONAL LIFT FM SHORTWAVE AND SFC TROUGH PASSING ACROSS EASTERN HALF OF LAKE SUPERIOR. EVENTUALLY...FLOW ALOFT BECOMES FLATTER OVR MUCH OF WESTERN HALF OF THE CONUS WHICH ALLOWS SHORTWAVE TROUGH CURRENTLY OFFSHORE OF WESTERN CONUS TO SHIFT INTO THE MIDDLE PORTION OF THE CONUS ON FRIDAY. ATTM...TRACK OF SHORTWAVE/SFC TROUGH KEEPS SNOW TO THE SOUTH OF CWA. YET...SINCE LARGE HIGH PRESSURE OVR CANADA HAS NOT ARRIVED BY THAT TIME...THERE IS STILL A POTENTIAL FOR TRACK OF THE LOW TO SHIFT FARTHER NORTH. DPROG/DT OF GFS/ECMWF INDICATE AN INCREASING NORTHERLY TREND TO NORTH EDGE OF SNOW SHIELD STREAKING ACROSS WI/IL. ON LATEST MODELS...THIS IS NOW INTO CNTRL WI. WILL KEEP DRY FCST FOR FRI ALONG WI BORDER...BUT SNOW MAY NEED TO BE INCLUDED IN LATER FORECASTS IF SIMILAR TREND CONTINUES. ANOTHER SHORTWAVE EMERGING FM TROUGH OVER WESTERN CANADA TRIES TO MAKE A RUN INTO WESTERN GREAT LAKES BY LATE WEEKEND. ALTHOUGH SFC HIGH/DRY AMBIENT AIR SHOULD KEEP PCPN TO A MINIMUM...INCLUDED A SMALL MENTION OF LIGHT SNOW SAT NIGHT INTO SUN AS WEAK SFC TROUGH TRIES TO MOVE THROUGH. GFS AN OUTLIER AT THIS POINT SHOWING STORM IN NORTHERN STREAM SHIFTING ACROSS NEXT TUE. 12Z ECMWF...OTHER GUIDANCE...AND THE HPC PREFERENCE...IS TO KEEP STORM TRACK FARTHER SOUTH SO CARRIED A DRY FCST MON/TUE. TEMPS REMAIN ON THE COOL SIDE OF CLIMATOLOGY THROUGH THE MIDDLE OF NEXT WEEK. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... IN THE WAKE OF THE SNOW SYSTEM EARLIER TODAY...ABUNDANT LOW-LEVEL MOISTURE LINGERS BACK TO NE MN. SO WITH UPSLOPING WNW FLOW...EXPECT KCMX TO REMAIN UNDER IFR/OCCASIONAL LIFR CONDITIONS THRU THE EVENING. MIGHT SEE A LITTLE -FZDZSN AS WELL...BUT THAT APPEARS TO BE A LOW PROBABILITY. WITH CLOUDS SCATTERING OUT IN NW MN...IT`S POSSIBLE CLOUDS COULD SCATTER OUT LATE AT KCMX...BUT AT THE MOMENT IT APPEARS MORE LIKELY THAT CIGS WILL SIMPLY RISE TO MVFR SINCE SFC DWPTS DON`T DROP SUBSTANTIALLY. MVFR CIGS SHOULD THEN LINGER THRU WED AFTN. AT KSAW...CIGS HAVE LIFTED TO MVFR OVER THE LAST FEW HRS. EXPECT MVFR CIGS TO PERSIST UNTIL LATER IN THE NIGHT WHEN ARRIVAL OF DRIER AIR WILL SCATTER OUT CLOUDS WITH ASSISTANCE OF DOWNSLOPING NW WINDS. WITH DAYTIME HEATING...MVFR CIGS WILL PROBABLY REDEVELOP WED MORNING AND THEN LIFT TO VFR IN THE AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW OVER NORTHERN ONTARIO WILL DRAG A COLD FRONT ACROSS LAKE SUPERIOR OVERNIGHT. THE LOW WILL DEEPEN AS IT MOVES TO JAMES BAY ON WEDNESDAY. LOOK FOR HIGH PRESSURE TO BUILD INTO THE NORTHERN PLAINS WEDNESDAY EVENING AND INTO THE UPPER GREAT LAKES ON THURSDAY. THIS HIGH WILL THEN BUILD THROUGH FRIDAY EVENING AND REMAIN NEARLY STATIONARY THROUGH SUNDAY. ALTHOUGH WINDS MAY REACH 30 KNOTS ON WEDNESDAY NIGHT/THURSDAY WITH THE INFLUX OF COLD AIR IN ADVANCE OF THE BUILDING RIDGE...NO GALES ARE EXPECTED DURING THIS FORECAST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SYNOPSIS/SHORT TERM DISCUSSION...KC LONG TERM DISCUSSION...JLA AVIATION...ROLFSON MARINE...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 735 PM EDT TUE MAR 18 2008 UPDATED AVIATION DISCUSSION FOR 00Z TAFS .SYNOPSIS... (ISSUED AT 355 PM EDT) 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW ACRS NAMERICA WITH NRN BRANCH TROFFING DOMINATING THE UP GRT LKS. DISTURBANCE EMBEDDED WITHIN THIS FLOW THAT WAS RESPONSIBLE FOR THE SN THAT FELL EARLIER IN THE DAY IS NOW HEADING ENEWD THRU ERN UPR MI. ACCOMPANYING PCPN HAS PRETTY MUCH ENDED WITH ARRIVAL OF DRIER AIR ALF (IN THE LYR COLDER THAN -10C) THAT WAS SHOWN ON THE 12Z MPX SNDG. BUT PLENTY OF LO CLD REMAINS WITH AMPLE LLVL MSTR LINGERING. THE HIER LLVL DWPTS (GENERALLY 30 TO 35) AND IFR/MVFR CIGS EXTEND WWD THRU MOST OF MN TO NEAR REINFORCING COLD FNT NOW MOVING INTO NW MN. SOME LGT PCPN HAS BEEN OBSVD ALG AND JUST AHD OF THIS BNDRY. BUT DRIER AIR IS NOTED MOVING IN BEHIND THE COLD FNT. THE CORE OF THE COLDER AIR IS LOCATED A BIT FARTHER N...WITH 12Z H85 TEMP AT YQD DOWN TO -11C...VS -5C OBSVD AT INL. && .SHORT TERM DISCUSSION (TNGT AND WED)... (ISSUED AT 355 PM EDT) MAIN FCST CONCERNS TNGT/TMRW ARE LGT PCPN CHCS/TYPE. NUMERICAL GUIDANCE HINTS COLD FNT NOW MOVING THRU MN WL MOVE INTO THE WRN ZNS ARND 06Z. WITH ABUNDANT LLVL MSTR NOTED AHEAD OF THIS BNDRY...MAINTAINED QUITE A BIT OF CLD COVER INTO THE OVERNGT AS WELL AS SOME PTCHY -DZ/-FZDZ/-SN ACRS MAINLY THE WRN ZNS WHERE LGT WLY FLOW WL UPSLOPE. ALSO INTRODUCED SOME LO CHC POPS FOR SIMILAR PCPN TYPE OVER THE ERN ZNS DOWNSTREAM OF LK SUP LATE TNGT WITH BETTER LLVL CNVGC ASSOCIATED WITH THE ARRIVAL OF THIS BNDRY. BUT INFLUX OF DRIER AIR LATE TNGT WL AT LEAST END THE POTENTIAL FOR -FZDZ OVER THE W AND BEGIN TO BREAK UP THE PERSISTENT CLD COVER IN THE DOWNSLOPE AREAS. IN ANY EVENT...LIMITED MOISTURE DEPTH AND MODEST CHILL (TEMPS WITHIN THE MOIST LYR FCST TO BE HIER THAN -10C) WL LIMIT PCPN COVG AND INTENSITY. TENDED TOWARD A BLEND OF ETA/GFS MOS GUIDANCE FOR MIN TEMPS FCST...WITH THE LOWER READINGS OVER THE W WITH MORE VIGOROUS LLVL DRYING LATE. ON WED...AN INCRSG N TO NW FLOW WL ADVECT COLDER AIR NOW OVER SCNTRL CAN INTO THE UPR GRT LKS. DURING MID WINTER...WOULD HAVE TO CONSIDER LES HEADLINES...BUT TIMING OF ARRIVAL OF COLDER AIR DURING THE DIURNAL HTG TIME AS WELL AS ACYC NATURE OF LARGER SCALE FLOW WL LIMIT LES BAND DVLPMNT/COVG/INTENSITY. ALTHOUGH FCST SHARP INVRN ARND H85 OR SO WL RESULT IN INCRSG SC DVLPMNT WITH THE DIURNAL HTG... THIS LO INVRN SHOULD LIMIT THE POTENTIAL FOR ANY INSTABILTY SHSN THAT MIGHT OTRW DVLP WELL INLAND WITH SFC HTG/INFLUX OF LLVL MSTR OFF THE LK. MIXING TO H85-825 ON GFS FCST SDNGS YIELDS HI TEMPS ARND 40 OVER THE SCNTRL...WHICH WL BE WARMEST WITH DOWNSLOPING NNW FLOW. .LONG TERM DISCUSSION (WEDNESDAY NIGHT THROUGH NEXT TUESDAY)... TROUGHING IN THE GREAT LAKES TO BEGIN THE PERIOD GRADUALLY GETS REPLACED BY FLATTER FLOW ALOFT. AS TROUGH RUNS INTO STRONG RIDGE OVR NORTH ATLANTIC/GREENLAND EXPECT IT TO STALL THIS WEEKEND WHEN IT REACHES NORTHERN NEW ENGLAND/EASTERN CANADA. USUALLY THIS PATTERN RESULTS IN A COLDER PATTERN FOR GREAT LAKES/MID ATLANTIC AND THIS TIME IS NO EXCEPTION. AT THE LEAST...EXPECT BLO NORMAL TEMPS THROUGH THE WEEKEND. ALSO...WITH H85 TEMPS TOWARD -12C COULD END UP WITH LIGHT LK EFFECT SNOW SHOWERS. DUE TO ONSHORE FLOW AND AT LEAST WEAK OVER WATER INSTABILITY...WENT AHEAD AND LINGERED SNOW SHOWERS INTO FRIDAY NEAR LK SUPERIOR. BEST CHANCE FOR A PERIOD OF SOME ACCUMULATION WOULD BE LATE WED NIGHT INTO THU WITH ADDITIONAL LIFT FM SHORTWAVE AND SFC TROUGH PASSING ACROSS EASTERN HALF OF LAKE SUPERIOR. EVENTUALLY...FLOW ALOFT BECOMES FLATTER OVR MUCH OF WESTERN HALF OF THE CONUS WHICH ALLOWS SHORTWAVE TROUGH CURRENTLY OFFSHORE OF WESTERN CONUS TO SHIFT INTO THE MIDDLE PORTION OF THE CONUS ON FRIDAY. ATTM...TRACK OF SHORTWAVE/SFC TROUGH KEEPS SNOW TO THE SOUTH OF CWA. YET...SINCE LARGE HIGH PRESSURE OVR CANADA HAS NOT ARRIVED BY THAT TIME...THERE IS STILL A POTENTIAL FOR TRACK OF THE LOW TO SHIFT FARTHER NORTH. DPROG/DT OF GFS/ECMWF INDICATE AN INCREASING NORTHERLY TREND TO NORTH EDGE OF SNOW SHIELD STREAKING ACROSS WI/IL. ON LATEST MODELS...THIS IS NOW INTO CNTRL WI. WILL KEEP DRY FCST FOR FRI ALONG WI BORDER...BUT SNOW MAY NEED TO BE INCLUDED IN LATER FORECASTS IF SIMILAR TREND CONTINUES. ANOTHER SHORTWAVE EMERGING FM TROUGH OVER WESTERN CANADA TRIES TO MAKE A RUN INTO WESTERN GREAT LAKES BY LATE WEEKEND. ALTHOUGH SFC HIGH/DRY AMBIENT AIR SHOULD KEEP PCPN TO A MINIMUM...INCLUDED A SMALL MENTION OF LIGHT SNOW SAT NIGHT INTO SUN AS WEAK SFC TROUGH TRIES TO MOVE THROUGH. GFS AN OUTLIER AT THIS POINT SHOWING STORM IN NORTHERN STREAM SHIFTING ACROSS NEXT TUE. 12Z ECMWF...OTHER GUIDANCE...AND THE HPC PREFERENCE...IS TO KEEP STORM TRACK FARTHER SOUTH SO CARRIED A DRY FCST MON/TUE. TEMPS REMAIN ON THE COOL SIDE OF CLIMATOLOGY THROUGH THE MIDDLE OF NEXT WEEK. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... IN THE WAKE OF THE SNOW SYSTEM EARLIER TODAY...ABUNDANT LOW-LEVEL MOISTURE LINGERS BACK TO NE MN. SO WITH UPSLOPING WNW FLOW...EXPECT KCMX TO REMAIN UNDER IFR/OCCASIONAL LIFR CONDITIONS THRU THE EVENING. MIGHT SEE A LITTLE -FZDZSN AS WELL...BUT THAT APPEARS TO BE A LOW PROBABILITY. WITH CLOUDS SCATTERING OUT IN NW MN...IT`S POSSIBLE CLOUDS COULD SCATTER OUT LATE AT KCMX...BUT AT THE MOMENT IT APPEARS MORE LIKELY THAT CIGS WILL SIMPLY RISE TO MVFR SINCE SFC DWPTS DON`T DROP SUBSTANTIALLY. MVFR CIGS SHOULD THEN LINGER THRU WED AFTN. AT KSAW...CIGS HAVE LIFTED TO MVFR OVER THE LAST FEW HRS. EXPECT MVFR CIGS TO PERSIST UNTIL LATER IN THE NIGHT WHEN ARRIVAL OF DRIER AIR WILL SCATTER OUT CLOUDS WITH ASSISTANCE OF DOWNSLOPING NW WINDS. WITH DAYTIME HEATING...MVFR CIGS WILL PROBABLY REDEVELOP WED MORNING AND THEN LIFT TO VFR IN THE AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW OVER NORTHERN ONTARIO WILL DRAG A COLD FRONT ACROSS LAKE SUPERIOR OVERNIGHT. THE LOW WILL DEEPEN AS IT MOVES TO JAMES BAY ON WEDNESDAY. LOOK FOR HIGH PRESSURE TO BUILD INTO THE NORTHERN PLAINS WEDNESDAY EVENING AND INTO THE UPPER GREAT LAKES ON THURSDAY. THIS HIGH WILL THEN BUILD THROUGH FRIDAY EVENING AND REMAIN NEARLY STATIONARY THROUGH SUNDAY. ALTHOUGH WINDS MAY REACH 30 KNOTS ON WEDNESDAY NIGHT/THURSDAY WITH THE INFLUX OF COLD AIR IN ADVANCE OF THE BUILDING RIDGE...NO GALES ARE EXPECTED DURING THIS FORECAST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM DISCUSSION...KC LONG TERM DISCUSSION...JLA AVIATION...ROLFSON MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 355 PM EDT TUE MAR 18 2008 .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW ACRS NAMERICA WITH NRN BRANCH TROFFING DOMINATING THE UP GRT LKS. DISTURBANCE EMBEDDED WITHIN THIS FLOW THAT WAS RESPONSIBLE FOR THE SN THAT FELL EARLIER IN THE DAY IS NOW HEADING ENEWD THRU ERN UPR MI. ACCOMPANYING PCPN HAS PRETTY MUCH ENDED WITH ARRIVAL OF DRIER AIR ALF (IN THE LYR COLDER THAN -10C) THAT WAS SHOWN ON THE 12Z MPX SNDG. BUT PLENTY OF LO CLD REMAINS WITH AMPLE LLVL MSTR LINGERING. THE HIER LLVL DWPTS (GENERALLY 30 TO 35) AND IFR/MVFR CIGS EXTEND WWD THRU MOST OF MN TO NEAR REINFORCING COLD FNT NOW MOVING INTO NW MN. SOME LGT PCPN HAS BEEN OBSVD ALG AND JUST AHD OF THIS BNDRY. BUT DRIER AIR IS NOTED MOVING IN BEHIND THE COLD FNT. THE CORE OF THE COLDER AIR IS LOCATED A BIT FARTHER N...WITH 12Z H85 TEMP AT YQD DOWN TO -11C...VS -5C OBSVD AT INL. && .SHORT TERM DISCUSSION (TNGT AND WED)... MAIN FCST CONCERNS TNGT/TMRW ARE LGT PCPN CHCS/TYPE. NUMERICAL GUIDANCE HINTS COLD FNT NOW MOVING THRU MN WL MOVE INTO THE WRN ZNS ARND 06Z. WITH ABUNDANT LLVL MSTR NOTED AHEAD OF THIS BNDRY...MAINTAINED QUITE A BIT OF CLD COVER INTO THE OVERNGT AS WELL AS SOME PTCHY -DZ/-FZDZ/-SN ACRS MAINLY THE WRN ZNS WHERE LGT WLY FLOW WL UPSLOPE. ALSO INTRODUCED SOME LO CHC POPS FOR SIMILAR PCPN TYPE OVER THE ERN ZNS DOWNSTREAM OF LK SUP LATE TNGT WITH BETTER LLVL CNVGC ASSOCIATED WITH THE ARRIVAL OF THIS BNDRY. BUT INFLUX OF DRIER AIR LATE TNGT WL AT LEAST END THE POTENTIAL FOR -FZDZ OVER THE W AND BEGIN TO BREAK UP THE PERSISTENT CLD COVER IN THE DOWNSLOPE AREAS. IN ANY EVENT...LIMITED MOISTURE DEPTH AND MODEST CHILL (TEMPS WITHIN THE MOIST LYR FCST TO BE HIER THAN -10C) WL LIMIT PCPN COVG AND INTENSITY. TENDED TOWARD A BLEND OF ETA/GFS MOS GUIDANCE FOR MIN TEMPS FCST...WITH THE LOWER READINGS OVER THE W WITH MORE VIGOROUS LLVL DRYING LATE. ON WED...AN INCRSG N TO NW FLOW WL ADVECT COLDER AIR NOW OVER SCNTRL CAN INTO THE UPR GRT LKS. DURING MID WINTER...WOULD HAVE TO CONSIDER LES HEADLINES...BUT TIMING OF ARRIVAL OF COLDER AIR DURING THE DIURNAL HTG TIME AS WELL AS ACYC NATURE OF LARGER SCALE FLOW WL LIMIT LES BAND DVLPMNT/COVG/INTENSITY. ALTHOUGH FCST SHARP INVRN ARND H85 OR SO WL RESULT IN INCRSG SC DVLPMNT WITH THE DIURNAL HTG... THIS LO INVRN SHOULD LIMIT THE POTENTIAL FOR ANY INSTABILTY SHSN THAT MIGHT OTRW DVLP WELL INLAND WITH SFC HTG/INFLUX OF LLVL MSTR OFF THE LK. MIXING TO H85-825 ON GFS FCST SDNGS YIELDS HI TEMPS ARND 40 OVER THE SCNTRL...WHICH WL BE WARMEST WITH DOWNSLOPING NNW FLOW. .LONG TERM DISCUSSION (WEDNESDAY NIGHT THROUGH NEXT TUESDAY)... TROUGHING IN THE GREAT LAKES TO BEGIN THE PERIOD GRADUALLY GETS REPLACED BY FLATTER FLOW ALOFT. AS TROUGH RUNS INTO STRONG RIDGE OVR NORTH ATLANTIC/GREENLAND EXPECT IT TO STALL THIS WEEKEND WHEN IT REACHES NORTHERN NEW ENGLAND/EASTERN CANADA. USUALLY THIS PATTERN RESULTS IN A COLDER PATTERN FOR GREAT LAKES/MID ATLANTIC AND THIS TIME IS NO EXCEPTION. AT THE LEAST...EXPECT BLO NORMAL TEMPS THROUGH THE WEEKEND. ALSO...WITH H85 TEMPS TOWARD -12C COULD END UP WITH LIGHT LK EFFECT SNOW SHOWERS. DUE TO ONSHORE FLOW AND AT LEAST WEAK OVER WATER INSTABILITY...WENT AHEAD AND LINGERED SNOW SHOWERS INTO FRIDAY NEAR LK SUPERIOR. BEST CHANCE FOR A PERIOD OF SOME ACCUMULATION WOULD BE LATE WED NIGHT INTO THU WITH ADDITIONAL LIFT FM SHORTWAVE AND SFC TROUGH PASSING ACROSS EASTERN HALF OF LAKE SUPERIOR. EVENTUALLY...FLOW ALOFT BECOMES FLATTER OVR MUCH OF WESTERN HALF OF THE CONUS WHICH ALLOWS SHORTWAVE TROUGH CURRENTLY OFFSHORE OF WESTERN CONUS TO SHIFT INTO THE MIDDLE PORTION OF THE CONUS ON FRIDAY. ATTM...TRACK OF SHORTWAVE/SFC TROUGH KEEPS SNOW TO THE SOUTH OF CWA. YET...SINCE LARGE HIGH PRESSURE OVR CANADA HAS NOT ARRIVED BY THAT TIME...THERE IS STILL A POTENTIAL FOR TRACK OF THE LOW TO SHIFT FARTHER NORTH. DPROG/DT OF GFS/ECMWF INDICATE AN INCREASING NORTHERLY TREND TO NORTH EDGE OF SNOW SHIELD STREAKING ACROSS WI/IL. ON LATEST MODELS...THIS IS NOW INTO CNTRL WI. WILL KEEP DRY FCST FOR FRI ALONG WI BORDER...BUT SNOW MAY NEED TO BE INCLUDED IN LATER FORECASTS IF SIMILAR TREND CONTINUES. ANOTHER SHORTWAVE EMERGING FM TROUGH OVER WESTERN CANADA TRIES TO MAKE A RUN INTO WESTERN GREAT LAKES BY LATE WEEKEND. ALTHOUGH SFC HIGH/DRY AMBIENT AIR SHOULD KEEP PCPN TO A MINIMUM...INCLUDED A SMALL MENTION OF LIGHT SNOW SAT NIGHT INTO SUN AS WEAK SFC TROUGH TRIES TO MOVE THROUGH. GFS AN OUTLIER AT THIS POINT SHOWING STORM IN NORTHERN STREAM SHIFTING ACROSS NEXT TUE. 12Z ECMWF...OTHER GUIDANCE...AND THE HPC PREFERENCE...IS TO KEEP STORM TRACK FARTHER SOUTH SO CARRIED A DRY FCST MON/TUE. TEMPS REMAIN ON THE COOL SIDE OF CLIMATOLOGY THROUGH THE MIDDLE OF NEXT WEEK. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... WITH THE ARRIVAL OF DRIER AIR ALF...THE STEADY PCPN AT BOTH CMX/SAW HAS ENDED. HOWEVER...EXPECT QUITE A BIT OF LO CLD TO LINGER THRU THE REST OF THIS AFTN/EVNG WITH INCRSGLY SHALLOW MOIST LYR REMAINING. SUSPECT THE VSBY AT SAW WL CLIMB TO VFR RANGE AS OBSVD UPSTREAM. BUT WEAK UPSLOPE FLOW LIKELY TO LINGER AT CMX SUGS VSBYS WL STAY IN THE IFR/MVFR RANGE THERE WITH SOME FZDZ/DZ PSBL. PASSAGE OF REINFORCING COLD FNT LATE TNGT WL OPEN THE DOOR TO DRIER AIR AND IMPROVING CONDITIONS...BUT MVFR CIGS WL LIKELY PERSIST UNDER DVLPG SUBSIDENCE INVRN EVEN THOUGH VSBY WL CLIMB TO VFR RANGE. BEST CHC FOR PERSISTENT MVFR CIGS WL BE AT CMX. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW OVER NORTHERN ONTARIO WILL DRAG A COLD FRONT ACROSS LAKE SUPERIOR OVERNIGHT. THE LOW WILL DEEPEN AS IT MOVES TO JAMES BAY ON WEDNESDAY. LOOK FOR HIGH PRESSURE TO BUILD INTO THE NORTHERN PLAINS WEDNESDAY EVENING AND INTO THE UPPER GREAT LAKES ON THURSDAY. THIS HIGH WILL THEN BUILD THROUGH FRIDAY EVENING AND REMAIN NEARLY STATIONARY THROUGH SUNDAY. ALTHOUGH WINDS MAY REACH 30 KNOTS ON WEDNESDAY NIGHT/THURSDAY WITH THE INFLUX OF COLD AIR IN ADVANCE OF THE BUILDING RIDGE...NO GALES ARE EXPECTED DURING THIS FORECAST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM DISCUSSION...KC LONG TERM DISCUSSION...JLA AVIATION...KC MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 125 PM EDT TUE MAR 18 2008 .UPDATE... EXPANDED THE ADVY AT 1148 AM TO INCLUDE MQT/ALGER/NRN SCHOOLCRAFT ZNS TO ACCOUNT FOR PERSISTENT BAND OF HEAVIER SN TIED CLOSELY TO GFS FCST SHARPER H7-5 FGEN. OTRW...RECENT TRENDS SHOW SN DIMINISHING OVER THE WRN ZNS WITH ARRIVAL OF DRIER AIR ALF. ISSUED SN ADVYS FOR THE NW HALF OF THE CWA AFT RECEIVING REPORT OF 4.5 INCHES OF SN AT IWD DURING THE NGT. AREA OF SN ON CYC SIDE OF TRACK OF SHRTWV MOVING THRU WI AND UNDER DEFORMATION ZN COLDER CLD TOPS HAS BEEN ENHANCED BY FAIRLY SHARP H7-5 FGEN. DESPITE ELEVATED AND RATHER SHALLOW DGZ...SN HAS FALLEN AT THE RATE OF AN INCH/HR AT SOME SPOTS WITH HIER SN/WATER RATIOS (ABOUT 16:1 AT IWD) THAN PREVIOUSLY EXPECTED WITH THE ENHANCED UVV/FGEN IMPACTING THE DGZ. BUT... LATEST RADAR IMAGERY/SFC OBS SHOW PCPN UPSTREAM IS BEGINNING TO DIMINISH WITH ARRIVAL OF DRIER AIR ALF AS INDICATED BY 12Z MPX SDNG/ WRMG CLD TOP TEMPS SHOWN ON IR STLT IMAGERY. BUT MUCH LO CLD/ FOG REMAINS WELL BACK INTO MN. AS THE WI SHRTWV CONTINUES TO THE ENE TDAY AND DRIER AIR ARRIVES ALF...EXPECT THE SN TO DIMINISH TO DZ WSW-ENE DURING THE DAY AS FCST. THE MOST SN WL FALL OVER THE W INTO THE NCNTRL ON THE CYC SIDE OF SHRTWV TRACK WHERE ADVYS ARE NOW POSTED. && .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS STILL SHOWS SPLIT FLOW ACROSS NORTH AMERICA. IN THE NORTHERN STREAM...A TROUGH STRETCHED FROM SOUTH CENTRAL CANADA INTO NEBRASKA...WITH RIDGES OVER THE GREAT LAKES AND PACIFIC NW. IN THE SOUTHERN STREAM...AN UPPER LOW EXISTS OVER NORTHERN MEXICO...WITH FAIRLY IMPRESSIVE RIDGES BOTH DOWNSTREAM OVER THE SE U.S. AND NEAR CALIFORNIA. IN-BETWEEN THE TWO STREAMS...A SHRTWV IS LOCATED OVER NW KS. ON WATER VAPOR AHEAD OF THE UPPER LOW AND NW KS SHRTWV...A SUBTROPICAL JET OF MOISTURE CAN BE SEEN SPREADING UP FROM THE DEEP TROPICS OF THE EAST PACIFIC... INTO MISSOURI AND LOWER MICHIGAN. IR IMAGERY REFLECTS THIS MOISTURE TOO WITH COLD CLOUD TOPS. PCPN UNDER THESE COLD CLOUD TOPS IS FOCUSED MOSTLY FROM IN/IL SOUTHWEST INTO TEXAS...WHERE A LOW LEVEL JET TRANSPORTING MOISTURE OUT OF THE GULF OF MEXICO IS INTERSECTING A WARM FRONT SITUATED FROM NE TEXAS INTO THE OHIO VALLEY. SETUP VERY FAVORABLE FOR HEAVY RAINFALL IN THIS REGION. TO THE NW OF THE SUBTROPICAL MOISTURE...WARMER BUT CONVECTIVE LOOK CLOUD TOPS ARE INDICATED FROM EASTERN SD INTO SRN MN...WI AND UPPER MI. RADAR IMAGERY ALSO REFLECTS THE CONVECTIVE LOOK...DUE TO 700-500MB LAPSE RATES OF 6.5-7C/KM PRESENT. PCPN IS MOSTLY IN THE FORM OF SNOW...AND FAIRLY WET AS EVIDENCED BY A DEEP AGGREGATE ZONE (UP TO 10000 FT) ON THE 00Z MPX SOUNDING. HOWEVER...SOME REPORTS OF DRIZZLE HAVE OCCURRED. THINKING IS THAT WITH THE -10C LAYER SO HIGH IN THE ATMOSPHERE...IT HAS A BETTER CHANCE OF DRYING OUT...RESULTING IN DRIZZLE INSTEAD OF SNOW. WATER VAPOR SORT OF DEPICTS THIS WITH MUCH OF THE MOISTURE WITH THE SUBTROPICAL JET. PCPN IS BEING DRIVEN BY ISENTROPIC LIFT ON THE 285K SURFACE...ALONG WITH DPVA AHEAD OF THE NW KS SHRTWV AND THE UPPER TROUGH CROSSING THE NORTHERN PLAINS. && .DISCUSSION... MAIN FORECAST CONCERN IS PCPN AND AMOUNTS TODAY. TODAY...SHRTWV OVER NW KS IS INDICATED TO CONTINUE LIFTING NE AS IT ENCOUNTERS THE GENERAL RIDGING PRESENT OVER THE EASTERN U.S.. BY 18Z...THE SHRTWV SHOULD REACH THE SOUTH CENTRAL U.P....THEN LIFT INTO NE ONTARIO BY 00Z. DPVA AHEAD OF THE SHRTWV...COMBINED WITH CONTINUED ISENTROPIC LIFT ON THE 285K SURFACE....SHOULD ALLOW PCPN TO EXPAND ACROSS UPPER MI EARLY THIS MORNING. ALL OF THE PCPN IS EXPECTED IN THE FORM OF SNOW...GIVEN THAT WET BULB ZERO HEIGHTS ARE INDICATED WELL BELOW 750 FT. ONCE THE SHRTWV PASSES...CAUSING DRYING OF THE MID LEVELS...THE SNOW WILL END. HOWEVER...THIS DRYING OF THE MID LEVELS MEANS THE LOW LEVELS STAY MOIST...SO SOME DRIZZLE IS POSSIBLE. TOTAL MODEL QPF AMOUNTS OF 0.10-0.25 INCH SEEM REASONABLE DURING THE TIME PERIOD OF THE SNOW (09Z-21Z)...ESPECIALLY WITH THE BULK OF THE DEEPER MOISTURE STUCK DOWN TO THE SOUTH OVER THE OHIO VALLEY AREA. GIVEN THE DEEP AGGREGATE ZONE SHOWN ON THE 00Z MPX SOUNDING AND FCST SOUNDINGS...SNOW TO WATER RATIOS WILL BE ON THE LOW SIDE...GENERALLY 10 TO 1 OR LESS. THUS...SNOWFALL AMOUNTS IN THE 1 TO LOCALLY 3 INCH RANGE SEEM REASONABLE. WITH CLOUDY SKIES THROUGH THE ENTIRE DAY...TEMPERATURES ARE NOT EXPECTED TO RISE MUCH. THE MAIN MECHANISM TO INCREASE TEMPS WILL LIKELY BE THE ADVECTION OF HIGHER DEWPOINTS INTO THE AREA...WHICH MEANS THERE IS POTENTIAL FOR FOG. SWITCH TO A NW WIND TOWARDS THE END OF THE DAY WILL ALLOW FOR LOWER DEWPOINTS TO ENTER IN AND DISSIPATE ANY FOG. TONIGHT...UPPER TROUGH OVER THE NORTHERN PLAINS IS PROGGED TO MOVE INTO UPPER MI. WITH THE TROUGH IS A WEAK SHRTWV...CURRENTLY IN CENTRAL NORTH DAKOTA...WHICH IS SHOWN TO MOVE THROUGH THE CWA DURING THE NIGHT. DPVA FROM THIS SHRTWV AND/OR UPSLOPE FLOW FROM WNW LOW LEVEL WINDS...COMBINED WITH LINGERING LOW LEVEL MOISTURE...MAY BE ENOUGH TO PRODUCE SOME FREEZING DRIZZLE OR LIGHT SNOW OVER THE WEST HALF OF UPPER MI. 850/925MB TEMPS ARE NOT COLD ENOUGH DURING THIS PERIOD TO THINK ABOUT LAKE EFFECT SNOW (ONLY DROPPING TO -7C AT MOST). OTHERWISE...THE NIGHT SHOULD BE FAIRLY QUIET WITH MOSTLY CLOUDY SKIES. THE CLOUDS WILL HELP HOLD TEMPS UP...THOUGH SOME COOLING IS EXPECTED WITH THE WNW LOW LEVEL FLOW. FOLLOWED CLOSE TO MAV GUIDANCE FOR LOWS. WEDNESDAY...CONTINUED COLD ADVECTION IS EXPECTED TO OCCUR DURING THE DAY WITH THE UPPER TROUGH GENERALLY OVERHEAD (850MB TEMPS FALL TO -10 TO -12C BY 00Z THU). ONE SHRTWV IS SHOWN TO MOVE SOUTH ON THE WEST SIDE OF THE UPPER TROUGH OVER NORTHERN ONTARIO...REACHING FAR NORTHERN LAKE SUPERIOR BY 00Z. THE COMBINATION OF THE STRONGER MARCH SUN AND THE COLD ADVECTION WILL HELP TO STEEPEN LOW LEVEL LAPSE RATES...AND WITH STILL SOME LOW LEVEL MOISTURE AROUND...SOME DIURNAL SNOW SHOWERS SEEM POSSIBLE. THUS 20-30 POPS REMAIN IN THE FORECAST. IN FACT...WOULD NOT BE SURPRISED TO SEE SOME LAKE EFFECT SNOW SHOWERS DEVELOP LATE IN THE DAY GIVEN THE 850MB TEMPS NOTED EARLIER. MADE VERY FEW CHANGES TO GOING HIGHS. ALTHOUGH 850MB TEMPS ARE COOLING... THEY PROMOTE BETTER MIXING...ESPECIALLY IN THE FAR SOUTH CENTRAL WITH THE DOWNSLOPING NW WIND. IN THIS AREA...READINGS SHOULD BE ABLE TO REACH THE 40 DEGREE MARK. WED NIGHT AND THU...SHRTWV AT 00Z THU OVER OR NEAR FAR NORTHERN LAKE SUPERIOR WILL END UP TAKING A SE TRACK...DUE TO A PHASING THAT IS PROGGED TO OCCUR OVER THE NORTHEAST U.S. WITH THE CURRENT UPPER LOW IN NORTHERN MEXICO AND THE UPPER TROUGH OVER OUR AREA ON WED. ACCOMPANYING THE SHRTWV WILL BE COLDER AIR YET...WITH 850MB TEMPS DROPPING AT LEAST ANOTHER 2C BY 12Z THU. THUS...LAKE EFFECT SNOW SHOWERS SEEM LIKELY...PARTICULARLY OVER EASTERN LAKE SUPERIOR WHERE THE COLDEST AIR CROSSES AND A LONGER FETCH OF ICE FREE AREA. LAKE EFFECT SNOW SHOWERS WILL BE ON THE DIMINISHING TREND DURING THE DAY THU AS DRY AIR AND WARMING 850MB TEMPS OCCUR WITH HIGH PRESSURE DROPPING SOUTH OUT OF NW ONTARIO. WITH THE COLDER AIR MOVING IN WED NIGHT...COOLED LOWS A BIT...PARTICULARLY IN THE LESS MODIFIED WESTERN U.P.. COOLED HIGHS A DEGREE OR TWO TOO FOR THU. THU NIGHT AND FRI...MODELS DEVELOP A FAIRLY DEEP STORM OVER THE CANADIAN MARITIMES THU NIGHT AS A RESULT OF THE PHASING THAT STARTED TO OCCUR ON THU. THIS STORM WILL HELP TO HOLD A TROUGH OVER NEW ENGLAND...WHICH MEANS HIGH PRESSURE ON ITS WEST SIDE OVER THE WESTERN GREAT LAKES. PREVIOUS RUNS OF MODELS WERE INDICATING SOME CLIPPER TYPE SYSTEM MOVING THROUGH IOWA THU NIGHT AND FRI TO HELP BRING SOME CLOUDS UP HERE. HOWEVER...WITH MORE EMPHASIS BEING PLACED ON THE CANADIAN MARITIMES STORM...THIS CLIPPER IS SUPPRESSED FARTHER SOUTH ACROSS KS AND MO. THUS...AFTER SOME LINGERING LAKE EFFECT SNOW OVER THE EASTERN CWA DIMINISHES THU EVENING DUE TO PERSISTENT DRY ADVECTION...DRY CONDITIONS WITH MOSTLY CLEAR SKIES ARE EXPECTED. WITH THE SURFACE RIDGE OVER THE CWA THU NIGHT...LIGHT WINDS AND DRY AIR (PRECIPITABLE WATER INDICATED AS LOW AS 0.10 OF AN INCH)...A FAVORABLE SCENARIO EXISTS TO GET CHILLY. LOWERED TEMPS INTO THE SINGLE DIGITS INLAND...AND WOULD NOT BE SURPRISED IF WE END UP WITH SOME BELOW ZERO READINGS. FUTURE SHIFTS MAY HAVE TO LOWER LOWS MORE. GIVEN THE COLDER TEMPS THU NIGHT...GENERAL LIGHT WINDS ON FRI TO PREVENT BETTER MIXING...HAVE LOWERED HIGHS A COUPLE DEGREES FOR FRI...DESPITE SUNSHINE. NO CHANGES MADE BEYOND FRI. WEEKEND STILL LOOKS DRY WITH THE GFS/ECMWF KEEPING THE SURFACE RIDGE ON FRI GENERALLY IN THE AREA. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... WITH THE ARRIVAL OF DRIER AIR ALF...THE STEADY PCPN AT BOTH CMX/SAW HAS ENDED. HOWEVER...EXPECT QUITE A BIT OF LO CLD TO LINGER THRU THE REST OF THIS AFTN/EVNG WITH INCRSGLY SHALLOW MOIST LYR REMAINING. SUSPECT THE VSBY AT SAW WL CLIMB TO VFR RANGE AS OBSVD UPSTREAM. BUT WEAK UPSLOPE FLOW LIKELY TO LINGER AT CMX SUGS VSBYS WL STAY IN THE IFR/MVFR RANGE THERE WITH SOME FZDZ/DZ PSBL. PASSAGE OF REINFORCING COLD FNT LATE TNGT WL OPEN THE DOOR TO DRIER AIR AND IMPROVING CONDITIONS...BUT MVFR CIGS WL LIKELY PERSIST UNDER DVLPG SUBSIDENCE INVRN EVEN THOUGH VSBY WL CLIMB TO VFR RANGE. BEST CHC FOR PERSISTENT MVFR CIGS WL BE AT CMX. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NO GALES EXPECTED IN THE WHOLE PERIOD. WINDS WILL COME UP TO 30 KNOTS OVER THE EAST WEDNESDAY INTO THURSDAY AS THE PRESSURE GRADIENT BETWEEN A LOW OVER NEW ENGLAND AND A HIGH PRESSURE OVER THE PLAINS CREATES A TIGHT PRESSURE GRADIENT ACROSS THE AREA. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...KC SYNOPSIS/DISCUSSION...AJ AVIATION...KC MARINE...GJM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1015 AM EDT TUE MAR 18 2008 .UPDATE... ISSUED SN ADVYS FOR THE NW HALF OF THE CWA AFT RECEIVING REPORT OF 4.5 INCHES OF SN AT IWD DURING THE NGT. AREA OF SN ON CYC SIDE OF TRACK OF SHRTWV MOVING THRU WI AND UNDER DEFORMATION ZN COLDER CLD TOPS HAS BEEN ENHANCED BY FAIRLY SHARP H7-5 FGEN. DESPITE ELEVATED AND RATHER SHALLOW DGZ...SN HAS FALLEN AT THE RATE OF AN INCH/HR AT SOME SPOTS WITH HIER SN/WATER RATIOS (ABOUT 16:1 AT IWD) THAN PREVIOUSLY EXPECTED WITH THE ENHANCED UVV/FGEN IMPACTING THE DGZ. BUT... LATEST RADAR IMAGERY/SFC OBS SHOW PCPN UPSTREAM IS BEGINNING TO DIMINISH WITH ARRIVAL OF DRIER AIR ALF AS INDICATED BY 12Z MPX SDNG/ WRMG CLD TOP TEMPS SHOWN ON IR STLT IMAGERY. BUT MUCH LO CLD/ FOG REMAINS WELL BACK INTO MN. AS THE WI SHRTWV CONTINUES TO THE ENE TDAY AND DRIER AIR ARRIVES ALF...EXPECT THE SN TO DIMINISH TO DZ WSW-ENE DURING THE DAY AS FCST. THE MOST SN WL FALL OVER THE W INTO THE NCNTRL ON THE CYC SIDE OF SHRTWV TRACK WHERE ADVYS ARE NOW POSTED. && .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS STILL SHOWS SPLIT FLOW ACROSS NORTH AMERICA. IN THE NORTHERN STREAM...A TROUGH STRETCHED FROM SOUTH CENTRAL CANADA INTO NEBRASKA...WITH RIDGES OVER THE GREAT LAKES AND PACIFIC NW. IN THE SOUTHERN STREAM...AN UPPER LOW EXISTS OVER NORTHERN MEXICO...WITH FAIRLY IMPRESSIVE RIDGES BOTH DOWNSTREAM OVER THE SE U.S. AND NEAR CALIFORNIA. IN-BETWEEN THE TWO STREAMS...A SHRTWV IS LOCATED OVER NW KS. ON WATER VAPOR AHEAD OF THE UPPER LOW AND NW KS SHRTWV...A SUBTROPICAL JET OF MOISTURE CAN BE SEEN SPREADING UP FROM THE DEEP TROPICS OF THE EAST PACIFIC... INTO MISSOURI AND LOWER MICHIGAN. IR IMAGERY REFLECTS THIS MOISTURE TOO WITH COLD CLOUD TOPS. PCPN UNDER THESE COLD CLOUD TOPS IS FOCUSED MOSTLY FROM IN/IL SOUTHWEST INTO TEXAS...WHERE A LOW LEVEL JET TRANSPORTING MOISTURE OUT OF THE GULF OF MEXICO IS INTERSECTING A WARM FRONT SITUATED FROM NE TEXAS INTO THE OHIO VALLEY. SETUP VERY FAVORABLE FOR HEAVY RAINFALL IN THIS REGION. TO THE NW OF THE SUBTROPICAL MOISTURE...WARMER BUT CONVECTIVE LOOK CLOUD TOPS ARE INDICATED FROM EASTERN SD INTO SRN MN...WI AND UPPER MI. RADAR IMAGERY ALSO REFLECTS THE CONVECTIVE LOOK...DUE TO 700-500MB LAPSE RATES OF 6.5-7C/KM PRESENT. PCPN IS MOSTLY IN THE FORM OF SNOW...AND FAIRLY WET AS EVIDENCED BY A DEEP AGGREGATE ZONE (UP TO 10000 FT) ON THE 00Z MPX SOUNDING. HOWEVER...SOME REPORTS OF DRIZZLE HAVE OCCURRED. THINKING IS THAT WITH THE -10C LAYER SO HIGH IN THE ATMOSPHERE...IT HAS A BETTER CHANCE OF DRYING OUT...RESULTING IN DRIZZLE INSTEAD OF SNOW. WATER VAPOR SORT OF DEPICTS THIS WITH MUCH OF THE MOISTURE WITH THE SUBTROPICAL JET. PCPN IS BEING DRIVEN BY ISENTROPIC LIFT ON THE 285K SURFACE...ALONG WITH DPVA AHEAD OF THE NW KS SHRTWV AND THE UPPER TROUGH CROSSING THE NORTHERN PLAINS. && .DISCUSSION... MAIN FORECAST CONCERN IS PCPN AND AMOUNTS TODAY. TODAY...SHRTWV OVER NW KS IS INDICATED TO CONTINUE LIFTING NE AS IT ENCOUNTERS THE GENERAL RIDGING PRESENT OVER THE EASTERN U.S.. BY 18Z...THE SHRTWV SHOULD REACH THE SOUTH CENTRAL U.P....THEN LIFT INTO NE ONTARIO BY 00Z. DPVA AHEAD OF THE SHRTWV...COMBINED WITH CONTINUED ISENTROPIC LIFT ON THE 285K SURFACE....SHOULD ALLOW PCPN TO EXPAND ACROSS UPPER MI EARLY THIS MORNING. ALL OF THE PCPN IS EXPECTED IN THE FORM OF SNOW...GIVEN THAT WET BULB ZERO HEIGHTS ARE INDICATED WELL BELOW 750 FT. ONCE THE SHRTWV PASSES...CAUSING DRYING OF THE MID LEVELS...THE SNOW WILL END. HOWEVER...THIS DRYING OF THE MID LEVELS MEANS THE LOW LEVELS STAY MOIST...SO SOME DRIZZLE IS POSSIBLE. TOTAL MODEL QPF AMOUNTS OF 0.10-0.25 INCH SEEM REASONABLE DURING THE TIME PERIOD OF THE SNOW (09Z-21Z)...ESPECIALLY WITH THE BULK OF THE DEEPER MOISTURE STUCK DOWN TO THE SOUTH OVER THE OHIO VALLEY AREA. GIVEN THE DEEP AGGREGATE ZONE SHOWN ON THE 00Z MPX SOUNDING AND FCST SOUNDINGS...SNOW TO WATER RATIOS WILL BE ON THE LOW SIDE...GENERALLY 10 TO 1 OR LESS. THUS...SNOWFALL AMOUNTS IN THE 1 TO LOCALLY 3 INCH RANGE SEEM REASONABLE. WITH CLOUDY SKIES THROUGH THE ENTIRE DAY...TEMPERATURES ARE NOT EXPECTED TO RISE MUCH. THE MAIN MECHANISM TO INCREASE TEMPS WILL LIKELY BE THE ADVECTION OF HIGHER DEWPOINTS INTO THE AREA...WHICH MEANS THERE IS POTENTIAL FOR FOG. SWITCH TO A NW WIND TOWARDS THE END OF THE DAY WILL ALLOW FOR LOWER DEWPOINTS TO ENTER IN AND DISSIPATE ANY FOG. TONIGHT...UPPER TROUGH OVER THE NORTHERN PLAINS IS PROGGED TO MOVE INTO UPPER MI. WITH THE TROUGH IS A WEAK SHRTWV...CURRENTLY IN CENTRAL NORTH DAKOTA...WHICH IS SHOWN TO MOVE THROUGH THE CWA DURING THE NIGHT. DPVA FROM THIS SHRTWV AND/OR UPSLOPE FLOW FROM WNW LOW LEVEL WINDS...COMBINED WITH LINGERING LOW LEVEL MOISTURE...MAY BE ENOUGH TO PRODUCE SOME FREEZING DRIZZLE OR LIGHT SNOW OVER THE WEST HALF OF UPPER MI. 850/925MB TEMPS ARE NOT COLD ENOUGH DURING THIS PERIOD TO THINK ABOUT LAKE EFFECT SNOW (ONLY DROPPING TO -7C AT MOST). OTHERWISE...THE NIGHT SHOULD BE FAIRLY QUIET WITH MOSTLY CLOUDY SKIES. THE CLOUDS WILL HELP HOLD TEMPS UP...THOUGH SOME COOLING IS EXPECTED WITH THE WNW LOW LEVEL FLOW. FOLLOWED CLOSE TO MAV GUIDANCE FOR LOWS. WEDNESDAY...CONTINUED COLD ADVECTION IS EXPECTED TO OCCUR DURING THE DAY WITH THE UPPER TROUGH GENERALLY OVERHEAD (850MB TEMPS FALL TO -10 TO -12C BY 00Z THU). ONE SHRTWV IS SHOWN TO MOVE SOUTH ON THE WEST SIDE OF THE UPPER TROUGH OVER NORTHERN ONTARIO...REACHING FAR NORTHERN LAKE SUPERIOR BY 00Z. THE COMBINATION OF THE STRONGER MARCH SUN AND THE COLD ADVECTION WILL HELP TO STEEPEN LOW LEVEL LAPSE RATES...AND WITH STILL SOME LOW LEVEL MOISTURE AROUND...SOME DIURNAL SNOW SHOWERS SEEM POSSIBLE. THUS 20-30 POPS REMAIN IN THE FORECAST. IN FACT...WOULD NOT BE SURPRISED TO SEE SOME LAKE EFFECT SNOW SHOWERS DEVELOP LATE IN THE DAY GIVEN THE 850MB TEMPS NOTED EARLIER. MADE VERY FEW CHANGES TO GOING HIGHS. ALTHOUGH 850MB TEMPS ARE COOLING... THEY PROMOTE BETTER MIXING...ESPECIALLY IN THE FAR SOUTH CENTRAL WITH THE DOWNSLOPING NW WIND. IN THIS AREA...READINGS SHOULD BE ABLE TO REACH THE 40 DEGREE MARK. WED NIGHT AND THU...SHRTWV AT 00Z THU OVER OR NEAR FAR NORTHERN LAKE SUPERIOR WILL END UP TAKING A SE TRACK...DUE TO A PHASING THAT IS PROGGED TO OCCUR OVER THE NORTHEAST U.S. WITH THE CURRENT UPPER LOW IN NORTHERN MEXICO AND THE UPPER TROUGH OVER OUR AREA ON WED. ACCOMPANYING THE SHRTWV WILL BE COLDER AIR YET...WITH 850MB TEMPS DROPPING AT LEAST ANOTHER 2C BY 12Z THU. THUS...LAKE EFFECT SNOW SHOWERS SEEM LIKELY...PARTICULARLY OVER EASTERN LAKE SUPERIOR WHERE THE COLDEST AIR CROSSES AND A LONGER FETCH OF ICE FREE AREA. LAKE EFFECT SNOW SHOWERS WILL BE ON THE DIMINISHING TREND DURING THE DAY THU AS DRY AIR AND WARMING 850MB TEMPS OCCUR WITH HIGH PRESSURE DROPPING SOUTH OUT OF NW ONTARIO. WITH THE COLDER AIR MOVING IN WED NIGHT...COOLED LOWS A BIT...PARTICULARLY IN THE LESS MODIFIED WESTERN U.P.. COOLED HIGHS A DEGREE OR TWO TOO FOR THU. THU NIGHT AND FRI...MODELS DEVELOP A FAIRLY DEEP STORM OVER THE CANADIAN MARITIMES THU NIGHT AS A RESULT OF THE PHASING THAT STARTED TO OCCUR ON THU. THIS STORM WILL HELP TO HOLD A TROUGH OVER NEW ENGLAND...WHICH MEANS HIGH PRESSURE ON ITS WEST SIDE OVER THE WESTERN GREAT LAKES. PREVIOUS RUNS OF MODELS WERE INDICATING SOME CLIPPER TYPE SYSTEM MOVING THROUGH IOWA THU NIGHT AND FRI TO HELP BRING SOME CLOUDS UP HERE. HOWEVER...WITH MORE EMPHASIS BEING PLACED ON THE CANADIAN MARITIMES STORM...THIS CLIPPER IS SUPPRESSED FARTHER SOUTH ACROSS KS AND MO. THUS...AFTER SOME LINGERING LAKE EFFECT SNOW OVER THE EASTERN CWA DIMINISHES THU EVENING DUE TO PERSISTENT DRY ADVECTION...DRY CONDITIONS WITH MOSTLY CLEAR SKIES ARE EXPECTED. WITH THE SURFACE RIDGE OVER THE CWA THU NIGHT...LIGHT WINDS AND DRY AIR (PRECIPITABLE WATER INDICATED AS LOW AS 0.10 OF AN INCH)...A FAVORABLE SCENARIO EXISTS TO GET CHILLY. LOWERED TEMPS INTO THE SINGLE DIGITS INLAND...AND WOULD NOT BE SURPRISED IF WE END UP WITH SOME BELOW ZERO READINGS. FUTURE SHIFTS MAY HAVE TO LOWER LOWS MORE. GIVEN THE COLDER TEMPS THU NIGHT...GENERAL LIGHT WINDS ON FRI TO PREVENT BETTER MIXING...HAVE LOWERED HIGHS A COUPLE DEGREES FOR FRI...DESPITE SUNSHINE. NO CHANGES MADE BEYOND FRI. WEEKEND STILL LOOKS DRY WITH THE GFS/ECMWF KEEPING THE SURFACE RIDGE ON FRI GENERALLY IN THE AREA. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... HEAVIEST SNOW WILL CONTINUE THIS MORNING WITH LIFR CONDITIONS FOR CIGS AND IFR CIGS AT KCMX BEFORE CONDITIONS IMPROVE THIS AFTERNOON TO BETTER VIS WITH WEST WINDS. ONLY PROBLEM IS WEST WIND STILL IS UPSLOPE AT KCMX...SO EXPECTING LIFR CIGS TO CONTINUE THROUGH THE REST OF THE PERIOD WITH -DZ...FZDZSN AND FOG WITH LOW LEVEL MOISTURE REMAINING TRAPPED UNDER AN INVERSION. KSAW WILL HAVE MVFR TO IFR CONDITIONS THIS MORNING WITH LIGHT SNOW AND CIGS GRADUALLY LOWERING WITH THE LOWER VIS. THE HEAVIEST SNOW LOOKS TO BE EARLY THIS AFTERNOON WITH LIFR CONDITIONS AND SOME DRIZZLE AFTER THE SNOW MOVES OUT BY MID AFTERNOON. AS WINDS GO TO THE WEST TOWARDS EVENING...VIS SHOULD IMPROVE AND CIGS SHOULD START TO COME UP AT KSAW AND THEN REMAIN IN THE MVFR CATEGORY BY MID EVENING ONWARD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NO GALES EXPECTED IN THE WHOLE PERIOD. WINDS WILL COME UP TO 30 KNOTS OVER THE EAST WEDNESDAY INTO THURSDAY AS THE PRESSURE GRADIENT BETWEEN A LOW OVER NEW ENGLAND AND A HIGH PRESSURE OVER THE PLAINS CREATES A TIGHT PRESSURE GRADIENT ACROSS THE AREA. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... SNOW ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR MIZ001-003-004- 084. SNOW ADVISORY UNTIL NOON EDT /11 AM CDT/ TODAY FOR MIZ002-009- 010. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ UPDATE...KC SYNOPSIS/DISCUSSION...AJ AVIATION/MARINE...GJM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 706 AM EDT TUE MAR 18 2008 .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS STILL SHOWS SPLIT FLOW ACROSS NORTH AMERICA. IN THE NORTHERN STREAM...A TROUGH STRETCHED FROM SOUTH CENTRAL CANADA INTO NEBRASKA...WITH RIDGES OVER THE GREAT LAKES AND PACIFIC NW. IN THE SOUTHERN STREAM...AN UPPER LOW EXISTS OVER NORTHERN MEXICO...WITH FAIRLY IMPRESSIVE RIDGES BOTH DOWNSTREAM OVER THE SE U.S. AND NEAR CALIFORNIA. IN-BETWEEN THE TWO STREAMS...A SHRTWV IS LOCATED OVER NW KS. ON WATER VAPOR AHEAD OF THE UPPER LOW AND NW KS SHRTWV...A SUBTROPICAL JET OF MOISTURE CAN BE SEEN SPREADING UP FROM THE DEEP TROPICS OF THE EAST PACIFIC... INTO MISSOURI AND LOWER MICHIGAN. IR IMAGERY REFLECTS THIS MOISTURE TOO WITH COLD CLOUD TOPS. PCPN UNDER THESE COLD CLOUD TOPS IS FOCUSED MOSTLY FROM IN/IL SOUTHWEST INTO TEXAS...WHERE A LOW LEVEL JET TRANSPORTING MOISTURE OUT OF THE GULF OF MEXICO IS INTERSECTING A WARM FRONT SITUATED FROM NE TEXAS INTO THE OHIO VALLEY. SETUP VERY FAVORABLE FOR HEAVY RAINFALL IN THIS REGION. TO THE NW OF THE SUBTROPICAL MOISTURE...WARMER BUT CONVECTIVE LOOK CLOUD TOPS ARE INDICATED FROM EASTERN SD INTO SRN MN...WI AND UPPER MI. RADAR IMAGERY ALSO REFLECTS THE CONVECTIVE LOOK...DUE TO 700-500MB LAPSE RATES OF 6.5-7C/KM PRESENT. PCPN IS MOSTLY IN THE FORM OF SNOW...AND FAIRLY WET AS EVIDENCED BY A DEEP AGGREGATE ZONE (UP TO 10000 FT) ON THE 00Z MPX SOUNDING. HOWEVER...SOME REPORTS OF DRIZZLE HAVE OCCURRED. THINKING IS THAT WITH THE -10C LAYER SO HIGH IN THE ATMOSPHERE...IT HAS A BETTER CHANCE OF DRYING OUT...RESULTING IN DRIZZLE INSTEAD OF SNOW. WATER VAPOR SORT OF DEPICTS THIS WITH MUCH OF THE MOISTURE WITH THE SUBTROPICAL JET. PCPN IS BEING DRIVEN BY ISENTROPIC LIFT ON THE 285K SURFACE...ALONG WITH DPVA AHEAD OF THE NW KS SHRTWV AND THE UPPER TROUGH CROSSING THE NORTHERN PLAINS. && .DISCUSSION... MAIN FORECAST CONCERN IS PCPN AND AMOUNTS TODAY. TODAY...SHRTWV OVER NW KS IS INDICATED TO CONTINUE LIFTING NE AS IT ENCOUNTERS THE GENERAL RIDGING PRESENT OVER THE EASTERN U.S.. BY 18Z...THE SHRTWV SHOULD REACH THE SOUTH CENTRAL U.P....THEN LIFT INTO NE ONTARIO BY 00Z. DPVA AHEAD OF THE SHRTWV...COMBINED WITH CONTINUED ISENTROPIC LIFT ON THE 285K SURFACE....SHOULD ALLOW PCPN TO EXPAND ACROSS UPPER MI EARLY THIS MORNING. ALL OF THE PCPN IS EXPECTED IN THE FORM OF SNOW...GIVEN THAT WET BULB ZERO HEIGHTS ARE INDICATED WELL BELOW 750 FT. ONCE THE SHRTWV PASSES...CAUSING DRYING OF THE MID LEVELS...THE SNOW WILL END. HOWEVER...THIS DRYING OF THE MID LEVELS MEANS THE LOW LEVELS STAY MOIST...SO SOME DRIZZLE IS POSSIBLE. TOTAL MODEL QPF AMOUNTS OF 0.10-0.25 INCH SEEM REASONABLE DURING THE TIME PERIOD OF THE SNOW (09Z-21Z)...ESPECIALLY WITH THE BULK OF THE DEEPER MOISTURE STUCK DOWN TO THE SOUTH OVER THE OHIO VALLEY AREA. GIVEN THE DEEP AGGREGATE ZONE SHOWN ON THE 00Z MPX SOUNDING AND FCST SOUNDINGS...SNOW TO WATER RATIOS WILL BE ON THE LOW SIDE...GENERALLY 10 TO 1 OR LESS. THUS...SNOWFALL AMOUNTS IN THE 1 TO LOCALLY 3 INCH RANGE SEEM REASONABLE. WITH CLOUDY SKIES THROUGH THE ENTIRE DAY...TEMPERATURES ARE NOT EXPECTED TO RISE MUCH. THE MAIN MECHANISM TO INCREASE TEMPS WILL LIKELY BE THE ADVECTION OF HIGHER DEWPOINTS INTO THE AREA...WHICH MEANS THERE IS POTENTIAL FOR FOG. SWITCH TO A NW WIND TOWARDS THE END OF THE DAY WILL ALLOW FOR LOWER DEWPOINTS TO ENTER IN AND DISSIPATE ANY FOG. TONIGHT...UPPER TROUGH OVER THE NORTHERN PLAINS IS PROGGED TO MOVE INTO UPPER MI. WITH THE TROUGH IS A WEAK SHRTWV...CURRENTLY IN CENTRAL NORTH DAKOTA...WHICH IS SHOWN TO MOVE THROUGH THE CWA DURING THE NIGHT. DPVA FROM THIS SHRTWV AND/OR UPSLOPE FLOW FROM WNW LOW LEVEL WINDS...COMBINED WITH LINGERING LOW LEVEL MOISTURE...MAY BE ENOUGH TO PRODUCE SOME FREEZING DRIZZLE OR LIGHT SNOW OVER THE WEST HALF OF UPPER MI. 850/925MB TEMPS ARE NOT COLD ENOUGH DURING THIS PERIOD TO THINK ABOUT LAKE EFFECT SNOW (ONLY DROPPING TO -7C AT MOST). OTHERWISE...THE NIGHT SHOULD BE FAIRLY QUIET WITH MOSTLY CLOUDY SKIES. THE CLOUDS WILL HELP HOLD TEMPS UP...THOUGH SOME COOLING IS EXPECTED WITH THE WNW LOW LEVEL FLOW. FOLLOWED CLOSE TO MAV GUIDANCE FOR LOWS. WEDNESDAY...CONTINUED COLD ADVECTION IS EXPECTED TO OCCUR DURING THE DAY WITH THE UPPER TROUGH GENERALLY OVERHEAD (850MB TEMPS FALL TO -10 TO -12C BY 00Z THU). ONE SHRTWV IS SHOWN TO MOVE SOUTH ON THE WEST SIDE OF THE UPPER TROUGH OVER NORTHERN ONTARIO...REACHING FAR NORTHERN LAKE SUPERIOR BY 00Z. THE COMBINATION OF THE STRONGER MARCH SUN AND THE COLD ADVECTION WILL HELP TO STEEPEN LOW LEVEL LAPSE RATES...AND WITH STILL SOME LOW LEVEL MOISTURE AROUND...SOME DIURNAL SNOW SHOWERS SEEM POSSIBLE. THUS 20-30 POPS REMAIN IN THE FORECAST. IN FACT...WOULD NOT BE SURPRISED TO SEE SOME LAKE EFFECT SNOW SHOWERS DEVELOP LATE IN THE DAY GIVEN THE 850MB TEMPS NOTED EARLIER. MADE VERY FEW CHANGES TO GOING HIGHS. ALTHOUGH 850MB TEMPS ARE COOLING... THEY PROMOTE BETTER MIXING...ESPECIALLY IN THE FAR SOUTH CENTRAL WITH THE DOWNSLOPING NW WIND. IN THIS AREA...READINGS SHOULD BE ABLE TO REACH THE 40 DEGREE MARK. WED NIGHT AND THU...SHRTWV AT 00Z THU OVER OR NEAR FAR NORTHERN LAKE SUPERIOR WILL END UP TAKING A SE TRACK...DUE TO A PHASING THAT IS PROGGED TO OCCUR OVER THE NORTHEAST U.S. WITH THE CURRENT UPPER LOW IN NORTHERN MEXICO AND THE UPPER TROUGH OVER OUR AREA ON WED. ACCOMPANYING THE SHRTWV WILL BE COLDER AIR YET...WITH 850MB TEMPS DROPPING AT LEAST ANOTHER 2C BY 12Z THU. THUS...LAKE EFFECT SNOW SHOWERS SEEM LIKELY...PARTICULARLY OVER EASTERN LAKE SUPERIOR WHERE THE COLDEST AIR CROSSES AND A LONGER FETCH OF ICE FREE AREA. LAKE EFFECT SNOW SHOWERS WILL BE ON THE DIMINISHING TREND DURING THE DAY THU AS DRY AIR AND WARMING 850MB TEMPS OCCUR WITH HIGH PRESSURE DROPPING SOUTH OUT OF NW ONTARIO. WITH THE COLDER AIR MOVING IN WED NIGHT...COOLED LOWS A BIT...PARTICULARLY IN THE LESS MODIFIED WESTERN U.P.. COOLED HIGHS A DEGREE OR TWO TOO FOR THU. THU NIGHT AND FRI...MODELS DEVELOP A FAIRLY DEEP STORM OVER THE CANADIAN MARITIMES THU NIGHT AS A RESULT OF THE PHASING THAT STARTED TO OCCUR ON THU. THIS STORM WILL HELP TO HOLD A TROUGH OVER NEW ENGLAND...WHICH MEANS HIGH PRESSURE ON ITS WEST SIDE OVER THE WESTERN GREAT LAKES. PREVIOUS RUNS OF MODELS WERE INDICATING SOME CLIPPER TYPE SYSTEM MOVING THROUGH IOWA THU NIGHT AND FRI TO HELP BRING SOME CLOUDS UP HERE. HOWEVER...WITH MORE EMPHASIS BEING PLACED ON THE CANADIAN MARITIMES STORM...THIS CLIPPER IS SUPPRESSED FARTHER SOUTH ACROSS KS AND MO. THUS...AFTER SOME LINGERING LAKE EFFECT SNOW OVER THE EASTERN CWA DIMINISHES THU EVENING DUE TO PERSISTENT DRY ADVECTION...DRY CONDITIONS WITH MOSTLY CLEAR SKIES ARE EXPECTED. WITH THE SURFACE RIDGE OVER THE CWA THU NIGHT...LIGHT WINDS AND DRY AIR (PRECIPITABLE WATER INDICATED AS LOW AS 0.10 OF AN INCH)...A FAVORABLE SCENARIO EXISTS TO GET CHILLY. LOWERED TEMPS INTO THE SINGLE DIGITS INLAND...AND WOULD NOT BE SURPRISED IF WE END UP WITH SOME BELOW ZERO READINGS. FUTURE SHIFTS MAY HAVE TO LOWER LOWS MORE. GIVEN THE COLDER TEMPS THU NIGHT...GENERAL LIGHT WINDS ON FRI TO PREVENT BETTER MIXING...HAVE LOWERED HIGHS A COUPLE DEGREES FOR FRI...DESPITE SUNSHINE. NO CHANGES MADE BEYOND FRI. WEEKEND STILL LOOKS DRY WITH THE GFS/ECMWF KEEPING THE SURFACE RIDGE ON FRI GENERALLY IN THE AREA. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... HEAVIEST SNOW WILL CONTINUE THIS MORNING WITH LIFR CONDITIONS FOR CIGS AND IFR CIGS AT KCMX BEFORE CONDITIONS IMPROVE THIS AFTERNOON TO BETTER VIS WITH WEST WINDS. ONLY PROBLEM IS WEST WIND STILL IS UPSLOPE AT KCMX...SO EXPECTING LIFR CIGS TO CONTINUE THROUGH THE REST OF THE PERIOD WITH -DZ...FZDZSN AND FOG WITH LOW LEVEL MOISTURE REMAINING TRAPPED UNDER AN INVERSION. KSAW WILL HAVE MVFR TO IFR CONDITIONS THIS MORNING WITH LIGHT SNOW AND CIGS GRADUALLY LOWERING WITH THE LOWER VIS. THE HEAVIEST SNOW LOOKS TO BE EARLY THIS AFTERNOON WITH LIFR CONDITIONS AND SOME DRIZZLE AFTER THE SNOW MOVES OUT BY MID AFTERNOON. AS WINDS GO TO THE WEST TOWARDS EVENING...VIS SHOULD IMPROVE AND CIGS SHOULD START TO COME UP AT KSAW AND THEN REMAIN IN THE MVFR CATEGORY BY MID EVENING ONWARD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NO GALES EXPECTED IN THE WHOLE PERIOD. WINDS WILL COME UP TO 30 KNOTS OVER THE EAST WEDNESDAY INTO THURSDAY AS THE PRESSURE GRADIENT BETWEEN A LOW OVER NEW ENGLAND AND A HIGH PRESSURE OVER THE PLAINS CREATES A TIGHT PRESSURE GRADIENT ACROSS THE AREA. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION/MARINE...GJM mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 131 AM EDT TUE MAR 18 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .UPDATE... (ISSUED AT 1037 PM EDT) WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW PATTERN ACROSS THE CONUS/SRN CANADA WITH A TROF OVER THE NRN PLAINS IN ONE OF THE BRANCHES. MAIN SHORTWAVE OF NOTE IS THE ONE LIFTING NE INTO NEBRASKA. AHEAD OF THE TROF/SHORTWAVE...ISENTROPIC ASCENT IS GENERATING A SLOWLY EXPANDING AREA OF PCPN FROM NEBRASKA TO MN. CLOSER TO HOME...UPPER DIVERGENCE IN RIGHT ENTRANCE OF JET STREAK FROM LAKE SUPERIOR EWD HAS BEEN SUPPORTING A BAND OF -SN ACROSS WRN INTO NRN UPPER MI. MEANWHILE...A FEED OF DRIER AIR IN THE LOWER LEVELS IS ALSO OCCURRING FROM THE SE. SFC DWPTS ACROSS CNTRL/NRN LWR MI ARE STILL IN THE UPPER TEENS/LWR 20S. THIS DRIER IS ALSO NOTED JUST OFF THE SFC ON THE 00Z KAPX/KGRB SOUNDINGS AND EVENING TAMDAR SOUNDINGS. IMPACT HAS BEEN FOR LIFTING OF CIGS IN PARTS OF ERN WI INTO SCNTRL UPPER MI NEAR LAKE MICHIGAN. FCST WAS UPDATED EARLIER THIS EVENING TO DELAY PCPN OVER THE SE FCST AREA BASED ON DRIER AIR MENTIONED ABOVE. IT APPEARS THIS DRIER AIR WILL ADVANCE A LITTLE FARTHER N AND SHOULD SLIGHTLY DELAY PCPN ONSET OVER THE E HALF OF THE FCST AREA. OTHERWISE...GOING FCST FOR THE OVERNIGHT APPEARS TO BE IN OVERALL GOOD SHAPE WITH POPS INCREASING FROM SW TO NE AS ISENTROPIC ASCENT DEVELOPS NE INTO UPPER MI. BEST COMBINATION OF ISENTROPIC ASCENT AND DEEP LAYER FORCING PER QVECTORS SHOULD OCCUR IN THE 09Z-15Z TIME FRAME WHICH IS INLINE WITH CATEGORICAL POPS ALREADY IN THE FCST ACROSS THE BOARD DURING THAT PERIOD. WITH MIXING RATIOS OF 3G/KG AVBL ON THE 290K SFC (700-775MB)...POTENTIAL IS THERE FOR UP TO 3 INCHES OF SNOW DURING THE 6HR PERIOD OF BEST ASCENT. HOWEVER...AS NOTED BY PREVIOUS SHIFT...LAYER OF DENDRITIC SNOW GROWTH TEMPS IS VERY ELEVATED...SO 3 INCHES MAY BE DIFFICULT TO ATTAIN. IN GENERAL...LOOKS LIKE SNOW TOTALS OF 1 TO 3 INCHES FOR THIS SNOW EVENT BY THE TIME IT ENDS. && .PREV DISCUSSION... (ISSUED AT 400 PM EDT) SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW PATTERN ACRS NAMERICA. ZONAL ARCTIC BRANCH NOTED OVER SRN CAN WITH FAIRLY VIGOROUS SHRTWV/ASSOCIATED SFC LO MOVING INTO FAR NW ONTARIO. VIGOROUS SUBTROPICAL JET CUTOFF LO NOTED OVER THE DESERT SW WITH A PLUME OF TROPICAL MSTR STREAMING NNEWD ON THE HEELS OF SSW H85 WINDS UP TO 60KTS AT OKC INTO THE CNTRL CONUS FEEDING DEEP CONVECTION/HVY RA IN CNTRL PLAINS/MID MS RIVER VALLEY CLOSER TO ASSOCIATED H85 STNRY/WARM FNT. IN BTWN THESE BRANCHES...A POLAR BRANCH FLOW OBSVD ACRS THE NRN STATES WITH FAIRLY WELL DEFINED SHRTWV OVER THE NRN PLAINS. ALTHOUGH QUITE A BIT OF MID/HI CLD IN ADVANCE OF THIS FEATURE AND ANOTHER SHRTWV LIFTING NE FM CO OUT OF THE SUBTROPICAL BRANCH CUTOFF HAS SPILLED INTO THE UPR GRT LKS...12Z GRB/APX RAOBS AND TAMDAR SDNGS SHOW A VERY DRY MID TROP OVER THE AREA. WITH SFC-H85 ACYC FLOW EXTENDING WWD FM HI CENTER IN QUEBEC INTO THE UPR LKS...NO SN HAS FALLEN SO FAR TDAY OVER THE FA. BUT...12Z MPX SDNG SHOWS DEEP SFC-H3 MSTR...AND SOME -SN HAS BROKEN OUT IN NE MN/NW WI AHEAD OF THIS RETURNING MSTR. A HEAVIER BATCH OF PCPN IS NOW MOVING INTO IA/SW MN IN AREA OF SHARPER DPVA AHEAD OF SHRTWV LIFTING NE FM CO/RRQ OF H3 JET AXIS THAT EXTENDED FM LK SUP TO NEAR ABR AT 12Z. SHORT TERM (TNGT AND TUE)... MAIN FORECAST CONCERNS DURING THIS PD IS PCPN COVG/TYPE/AMTS AND NEED FOR ANY HEADLINES. CONSIDERING THE RELIANCE OF THIS FCST ON THE INTERACTION OF THE VARIOUS BRANCHES DISCUSSED ABV...CONFIDENCE ON FCST EVOLUTION IS A BIT LOWER THAN EXPECTED FOR THIS SHORT TERM EVENT. FOR TNGT...GFS/NAM/LOCAL HI RES MODEL HAVE BEEN CONSISTENT SHOWING BAND OF -SN TO THE SW UNDER H4-2 DVGC IN RRQ OF JET AXIS DRIFTING ACRS THE FA THIS EVNG IN ADVANCE OF SHARPER DPVA/DEEP LYR H85-5 QVECTOR CNVGC FCST TO ARRIVE LATE TNGT AS SHRTWV NOW LIFTING NEWD FM CO MOVES TO SE MN BY 12Z TUE. WL GO WITH CHC POPS/SCT -SHSN THRU 06Z TO ACCOUNT FOR INITIAL WAVE OF -SN...THEN BUMP POPS UP TO CATEGORICAL AFT 06Z WITH ARRIVAL OF SHARPER DYNAMICS. ON TUE...SHRTWV IS FCST TO MOVE ACRS THE SE ZNS ARND 18Z AND INTO ONTARIO LATER IN THE DAY. EXPECT THE HIER QPF OVER THE W-CNTRL ON CYC SIDE OF THE TRACK OF THIS FEATURE...WITH MID LVL DRYING CUTTING DOWN ON THE PCPN TOTALS OVER THE SE. OTRW...EXPECT STEADY SN IN THE MRNG TO DIMINISH IN THE AFTN TO JUST SOME FLURRIES/-DZ WITH ARRIVAL OF DRIER AIR ALF AND IN LYRS WHERE THE TEMPS IS LOWER THAN -10C. NEITHER GFS/NAM FCST PROFILES SHOW FZRA/SLEET A LIKELY PCPN TYPE THRU THE EVENT. BEST CHC FOR THERE TO BE ANY PCPN TYPE BUT SN WL BE TUE AFTN WHEN TEMPS HAVE A CHC TO RECOVER FM SML DIURNAL TEMP FALL TNGT LIMITED BY WAD/ISENTROPIC LIFT. WL USE DZ TO COVER THAT PCPN TYPE WHEN MID LVL MSTR EXITS. AS FOR SN TOTALS...LOCAL HI RES MODEL SHOWS A FAIR AMT OF WATER EQUIVALENT PCPN (UP TO 0.40 INCH OR SO) FALLING OVER THE CNTRL ZNS DURING TUE MRNG ON CYC SIDE OF H5 VORT TRACK. CONSIDERING THE 3 G/KG SPECIFIC HUMIDITY NAM/GFS SHOW AVBL ON THE 290K SFC (H7-75)...THIS HI RES MODEL FCST DOES NOT APPEAR TOO OUT OF LINE. HOWEVER...SINCE THE CURRENT SHRTWV PLAYERS ARE OUT OF PHASE AND RICH TROPICAL MSTR WL BE INTERCEPTED ALG H85 WARM FNT WELL TO THE S...THINK SGNFT ADVY LEVEL PCPN IS UNLIKELY. ANOTHER NEGATIVE FOR HEAVY SN IS DGZ IS FCST TO BE ELEVATED AND RATHER NARROW IN DEPTH WITH INFLUX OF RELATIVELY WARM AIR BLO H7. LARGER SCALE MODELS (ESPECIALLY THE GFS) ALSO SHOW QUITE A BIT OF DRYING EVEN IN THE MRNG ABV H7. THIS FCST SEEMS A BIT UNREALISTIC OVER THE WCNTRL...WHICH WL BE IN BETTER POSITION RELATIVE TO THE VORT TRACK TO AVOID SGNFT DRYING ALF SO QUICKLY. IN ANY EVENT...WL NOT ISSUE ANY HEADLINES ATTM WITH PCPN/SN EFFICIENCY IN QUESTION. CONFIDENCE INCRSD BY LO NCEP FCST...WHICH SHOWS NO MORE THAN 2-3" THRU 00Z WED OVER THE WRN FA AND 1-2" OVER THE E. COORDINATED WITH APX/GRB/DLH. LONG TERM (TUESDAY NIGHT THROUGH NEXT MONDAY)... LOW PRESSURE TROUGH IN PROCESS OF EXITING UPR MI ON TUESDAY EVENING. DRY AIR IN MID LEVELS CONTINUES TO ERODE CHANCES OF ANY APPRECIABLE PCPN. LOW CHANCE POPS WERE RETAINED OVER EASTERN ZONES TO ACCOUNT FOR ANY TIMING DIFFERENCES OF EXITING PCPN SHIELD. OTHERWISE... CHANCES OF PCPN ON TUE NIGHT INTO WED MORNING LOOK MEAGER. TEMPS IN WAKE OF THE TROUGH NOT ALL THAT COLD WITH H9-H85 TEMPS ONLY AS LOW AS -7C...AND THIS IS OFF THE COLDER GFS OUTPUT. MOIST LOWER LAYERS BENEATH DRY LAYER ALOFT AND WNW UPSLOPE FLOW COULD YIELD FREEZING DRIZZLE/FLURRIES OVER THE WEST PORTION OF CWA. H5 TROUGH SLIDES ACROSS UPR LAKES ON WED WITH H5 TEMPS BLO -30C AND H7 TEMPS TOWARD -20C. MOISTURE FM H85 TO H7 IS LACKING. HOWEVER... LOW LEVEL LAPSE RATES TO H85 NEAR 8C/KM...LOW CONVECTIVE TEMPS...AND A SHORTWAVE PUSHING THROUGH TO ACT AS A TRIGGER MAY ALLOW FOR CU AND INSTABILITY SNOW SHOWERS. ONCE TROUGH OVR GREAT LAKES DEPARTS...LOOK FOR WEATHER TO BE FAIRLY TRANQUIL INTO THE WEEKEND. 00Z ECMWF FIT ASSOCIATED ENSEMBLES FM GFS/CANADIAN THE BEST SO...LIKE HPC...FOR THE MOST PART...PREFERRED ECMWF SOLUTION THROUGH THE EXTENDED. TROUGH THAT IS OVR GREAT LAKES REGION ON TUE EVENTUALLY LIFTS TOWARD EASTERN CANADA/NORTHERN NEW ENGLAND BY LATE WEEK. TROUGH WILL STALL THOUGH AS IT MEETS BUILDING RIDGE OVR NORTHERN ATLANTIC INTO GREENLAND. RESULT IS THE TROUGH HOLDING OVR EASTERN CANADA AND ADJACENT GREAT LAKES. THE PATTERN SHOULD KEEP A PERSISTENT CHILL TO THE TEMPS OVR MUCH OF THE GREAT LAKES INTO NEW ENGLAND THOUGH EARLY NEXT WEEK. EXPECT DAYTIME AND NIGHTTIME TEMPS TO RANGE FM 5-10 DEGREES BLO NORMAL. NEXT CHANCE OF ANY PCPN SKIRTS THE AREA LATE FRIDAY INTO SATURDAY. 00Z ECMWF WAS THE STRONGEST WITH SFC LOW MOVING INTO MN ON SATURDAY AND HAD QPF INTO WESTERN CWA BY 00Z SAT. TONED THAT IDEA DOWN AS OTHER MODELS WERE WEAKER WITH THE TROUGH AND EASTWARD EXTENT OF PCPN. SINCE CENTER OF LARGE/DRY CANADIAN HIGH PRES REMAINS OVR ONTARIO INTO GREAT LAKES...IMAGINE MOST PCPN WILL BE DEFLECTED TO WEST AND SOUTH OF THE CWA FRIDAY NIGHT INTO SAT. SOME LGT PCPN IS POSSIBLE AS UPR LEVEL WAVE SLIDES THROUGH ON SUN BUT WITH SFC HIGH AND DRY AIR IN VCNTY WILL NOT INCLUDE ANY MENTION ATTM. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... NARROW WEDGE OF LOW-LEVEL DRY AIR SHOULD ALLOW FOR VFR CONDITIONS FOR ANOTHER COUPLE OF HRS AT KCMX/KSAW. AFTER THAT...DISTURBANCE APPROACHING FROM THE SW WILL CAUSE DEVELOPMENT OF WIDESPREAD -SN WHICH WILL PERSIST THRU TUE MORNING. CIGS AND/OR VIS AT BOTH SITES SHOULD DROP TO LIFR LATE IN THE NIGHT WITH CONDITIONS LIKELY WORST AT KSAW DUE TO FAVORABLE UPSLOPING SE FLOW. PASSAGE OF SFC TROF AND RESULTING WIND SHIFT TO THE W OR NW WILL BRING IMPROVING CONDITIONS TO BOTH SITES LATE IN THE AFTN. BIGGEST IMPROVEMENT INITIALLY WILL BE WITH VIS. SLOW IMPROVEMENT SHOULD CONTINUE TUE EVENING WITH VIS BECOMING VFR...BUT CIGS SHOULD ONLY RISE TO THE LOWER END OF THE MVFR RANGE. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT A LOW NEAR HUDSON BAY TO DISSIPATE AS IT MOVES EASTWARD TONIGHT. ANOTHER LOW OVER SOUTHERN SASKATCHEWAN WILL DISSIPATE OVER NORTHWEST ONTARIO TUESDAY EVENING WHILE ANOTHER LOW PRESSURE SYSTEM GAINS STRENGTH OVER THE SOUTHERN PLAINS. THIS LOW WILL DEEPEN AS IT REACHES THE EASTERN GREAT LAKES WEDNESDAY EVENING. HIGH PRESSURE WILL THEN BUILD INTO THE NORTHERN PLAINS WEDNESDAY NIGHT AND THURSDAY MORNING. LOOK FOR THIS HIGH TO MOVE OVER THE UPPER GREAT LAKES THURSDAY AND REMAIN NEARLY STATIONARY THROUGH SATURDAY. THERE WILL BE NO GALES DURING THIS PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SYNOPSIS/SHORT TERM DISCUSSION...KC LONG TERM DISCUSSION...JLA AVIATION...ROLFSON MARINE...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1037 PM EDT MON MAR 17 2008 .UPDATE... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW PATTERN ACROSS THE CONUS/SRN CANADA WITH A TROF OVER THE NRN PLAINS IN ONE OF THE BRANCHES. MAIN SHORTWAVE OF NOTE IS THE ONE LIFTING NE INTO NEBRASKA. AHEAD OF THE TROF/SHORTWAVE...ISENTROPIC ASCENT IS GENERATING A SLOWLY EXPANDING AREA OF PCPN FROM NEBRASKA TO MN. CLOSER TO HOME...UPPER DIVERGENCE IN RIGHT ENTRANCE OF JET STREAK FROM LAKE SUPERIOR EWD HAS BEEN SUPPORTING A BAND OF -SN ACROSS WRN INTO NRN UPPER MI. MEANWHILE...A FEED OF DRIER AIR IN THE LOWER LEVELS IS ALSO OCCURRING FROM THE SE. SFC DWPTS ACROSS CNTRL/NRN LWR MI ARE STILL IN THE UPPER TEENS/LWR 20S. THIS DRIER IS ALSO NOTED JUST OFF THE SFC ON THE 00Z KAPX/KGRB SOUNDINGS AND EVENING TAMDAR SOUNDINGS. IMPACT HAS BEEN FOR LIFTING OF CIGS IN PARTS OF ERN WI INTO SCNTRL UPPER MI NEAR LAKE MICHIGAN. FCST WAS UPDATED EARLIER THIS EVENING TO DELAY PCPN OVER THE SE FCST AREA BASED ON DRIER AIR MENTIONED ABOVE. IT APPEARS THIS DRIER AIR WILL ADVANCE A LITTLE FARTHER N AND SHOULD SLIGHTLY DELAY PCPN ONSET OVER THE E HALF OF THE FCST AREA. OTHERWISE...GOING FCST FOR THE OVERNIGHT APPEARS TO BE IN OVERALL GOOD SHAPE WITH POPS INCREASING FROM SW TO NE AS ISENTROPIC ASCENT DEVELOPS NE INTO UPPER MI. BEST COMBINATION OF ISENTROPIC ASCENT AND DEEP LAYER FORCING PER QVECTORS SHOULD OCCUR IN THE 09Z-15Z TIME FRAME WHICH IS INLINE WITH CATEGORICAL POPS ALREADY IN THE FCST ACROSS THE BOARD DURING THAT PERIOD. WITH MIXING RATIOS OF 3G/KG AVBL ON THE 290K SFC (700-775MB)...POTENTIAL IS THERE FOR UP TO 3 INCHES OF SNOW DURING THE 6HR PERIOD OF BEST ASCENT. HOWEVER...AS NOTED BY PREVIOUS SHIFT...LAYER OF DENDRITIC SNOW GROWTH TEMPS IS VERY ELEVATED...SO 3 INCHES MAY BE DIFFICULT TO ATTAIN. IN GENERAL...LOOKS LIKE SNOW TOTALS OF 1 TO 3 INCHES FOR THIS SNOW EVENT BY THE TIME IT ENDS. && .PREV DISCUSSION... (ISSUED AT 400 PM EDT) SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW PATTERN ACRS NAMERICA. ZONAL ARCTIC BRANCH NOTED OVER SRN CAN WITH FAIRLY VIGOROUS SHRTWV/ASSOCIATED SFC LO MOVING INTO FAR NW ONTARIO. VIGOROUS SUBTROPICAL JET CUTOFF LO NOTED OVER THE DESERT SW WITH A PLUME OF TROPICAL MSTR STREAMING NNEWD ON THE HEELS OF SSW H85 WINDS UP TO 60KTS AT OKC INTO THE CNTRL CONUS FEEDING DEEP CONVECTION/HVY RA IN CNTRL PLAINS/MID MS RIVER VALLEY CLOSER TO ASSOCIATED H85 STNRY/WARM FNT. IN BTWN THESE BRANCHES...A POLAR BRANCH FLOW OBSVD ACRS THE NRN STATES WITH FAIRLY WELL DEFINED SHRTWV OVER THE NRN PLAINS. ALTHOUGH QUITE A BIT OF MID/HI CLD IN ADVANCE OF THIS FEATURE AND ANOTHER SHRTWV LIFTING NE FM CO OUT OF THE SUBTROPICAL BRANCH CUTOFF HAS SPILLED INTO THE UPR GRT LKS...12Z GRB/APX RAOBS AND TAMDAR SDNGS SHOW A VERY DRY MID TROP OVER THE AREA. WITH SFC-H85 ACYC FLOW EXTENDING WWD FM HI CENTER IN QUEBEC INTO THE UPR LKS...NO SN HAS FALLEN SO FAR TDAY OVER THE FA. BUT...12Z MPX SDNG SHOWS DEEP SFC-H3 MSTR...AND SOME -SN HAS BROKEN OUT IN NE MN/NW WI AHEAD OF THIS RETURNING MSTR. A HEAVIER BATCH OF PCPN IS NOW MOVING INTO IA/SW MN IN AREA OF SHARPER DPVA AHEAD OF SHRTWV LIFTING NE FM CO/RRQ OF H3 JET AXIS THAT EXTENDED FM LK SUP TO NEAR ABR AT 12Z. SHORT TERM (TNGT AND TUE)... MAIN FORECAST CONCERNS DURING THIS PD IS PCPN COVG/TYPE/AMTS AND NEED FOR ANY HEADLINES. CONSIDERING THE RELIANCE OF THIS FCST ON THE INTERACTION OF THE VARIOUS BRANCHES DISCUSSED ABV...CONFIDENCE ON FCST EVOLUTION IS A BIT LOWER THAN EXPECTED FOR THIS SHORT TERM EVENT. FOR TNGT...GFS/NAM/LOCAL HI RES MODEL HAVE BEEN CONSISTENT SHOWING BAND OF -SN TO THE SW UNDER H4-2 DVGC IN RRQ OF JET AXIS DRIFTING ACRS THE FA THIS EVNG IN ADVANCE OF SHARPER DPVA/DEEP LYR H85-5 QVECTOR CNVGC FCST TO ARRIVE LATE TNGT AS SHRTWV NOW LIFTING NEWD FM CO MOVES TO SE MN BY 12Z TUE. WL GO WITH CHC POPS/SCT -SHSN THRU 06Z TO ACCOUNT FOR INITIAL WAVE OF -SN...THEN BUMP POPS UP TO CATEGORICAL AFT 06Z WITH ARRIVAL OF SHARPER DYNAMICS. ON TUE...SHRTWV IS FCST TO MOVE ACRS THE SE ZNS ARND 18Z AND INTO ONTARIO LATER IN THE DAY. EXPECT THE HIER QPF OVER THE W-CNTRL ON CYC SIDE OF THE TRACK OF THIS FEATURE...WITH MID LVL DRYING CUTTING DOWN ON THE PCPN TOTALS OVER THE SE. OTRW...EXPECT STEADY SN IN THE MRNG TO DIMINISH IN THE AFTN TO JUST SOME FLURRIES/-DZ WITH ARRIVAL OF DRIER AIR ALF AND IN LYRS WHERE THE TEMPS IS LOWER THAN -10C. NEITHER GFS/NAM FCST PROFILES SHOW FZRA/SLEET A LIKELY PCPN TYPE THRU THE EVENT. BEST CHC FOR THERE TO BE ANY PCPN TYPE BUT SN WL BE TUE AFTN WHEN TEMPS HAVE A CHC TO RECOVER FM SML DIURNAL TEMP FALL TNGT LIMITED BY WAD/ISENTROPIC LIFT. WL USE DZ TO COVER THAT PCPN TYPE WHEN MID LVL MSTR EXITS. AS FOR SN TOTALS...LOCAL HI RES MODEL SHOWS A FAIR AMT OF WATER EQUIVALENT PCPN (UP TO 0.40 INCH OR SO) FALLING OVER THE CNTRL ZNS DURING TUE MRNG ON CYC SIDE OF H5 VORT TRACK. CONSIDERING THE 3 G/KG SPECIFIC HUMIDITY NAM/GFS SHOW AVBL ON THE 290K SFC (H7-75)...THIS HI RES MODEL FCST DOES NOT APPEAR TOO OUT OF LINE. HOWEVER...SINCE THE CURRENT SHRTWV PLAYERS ARE OUT OF PHASE AND RICH TROPICAL MSTR WL BE INTERCEPTED ALG H85 WARM FNT WELL TO THE S...THINK SGNFT ADVY LEVEL PCPN IS UNLIKELY. ANOTHER NEGATIVE FOR HEAVY SN IS DGZ IS FCST TO BE ELEVATED AND RATHER NARROW IN DEPTH WITH INFLUX OF RELATIVELY WARM AIR BLO H7. LARGER SCALE MODELS (ESPECIALLY THE GFS) ALSO SHOW QUITE A BIT OF DRYING EVEN IN THE MRNG ABV H7. THIS FCST SEEMS A BIT UNREALISTIC OVER THE WCNTRL...WHICH WL BE IN BETTER POSITION RELATIVE TO THE VORT TRACK TO AVOID SGNFT DRYING ALF SO QUICKLY. IN ANY EVENT...WL NOT ISSUE ANY HEADLINES ATTM WITH PCPN/SN EFFICIENCY IN QUESTION. CONFIDENCE INCRSD BY LO NCEP FCST...WHICH SHOWS NO MORE THAN 2-3" THRU 00Z WED OVER THE WRN FA AND 1-2" OVER THE E. COORDINATED WITH APX/GRB/DLH. LONG TERM (TUESDAY NIGHT THROUGH NEXT MONDAY)... LOW PRESSURE TROUGH IN PROCESS OF EXITING UPR MI ON TUESDAY EVENING. DRY AIR IN MID LEVELS CONTINUES TO ERODE CHANCES OF ANY APPRECIABLE PCPN. LOW CHANCE POPS WERE RETAINED OVER EASTERN ZONES TO ACCOUNT FOR ANY TIMING DIFFERENCES OF EXITING PCPN SHIELD. OTHERWISE... CHANCES OF PCPN ON TUE NIGHT INTO WED MORNING LOOK MEAGER. TEMPS IN WAKE OF THE TROUGH NOT ALL THAT COLD WITH H9-H85 TEMPS ONLY AS LOW AS -7C...AND THIS IS OFF THE COLDER GFS OUTPUT. MOIST LOWER LAYERS BENEATH DRY LAYER ALOFT AND WNW UPSLOPE FLOW COULD YIELD FREEZING DRIZZLE/FLURRIES OVER THE WEST PORTION OF CWA. H5 TROUGH SLIDES ACROSS UPR LAKES ON WED WITH H5 TEMPS BLO -30C AND H7 TEMPS TOWARD -20C. MOISTURE FM H85 TO H7 IS LACKING. HOWEVER... LOW LEVEL LAPSE RATES TO H85 NEAR 8C/KM...LOW CONVECTIVE TEMPS...AND A SHORTWAVE PUSHING THROUGH TO ACT AS A TRIGGER MAY ALLOW FOR CU AND INSTABILITY SNOW SHOWERS. ONCE TROUGH OVR GREAT LAKES DEPARTS...LOOK FOR WEATHER TO BE FAIRLY TRANQUIL INTO THE WEEKEND. 00Z ECMWF FIT ASSOCIATED ENSEMBLES FM GFS/CANADIAN THE BEST SO...LIKE HPC...FOR THE MOST PART...PREFERRED ECMWF SOLUTION THROUGH THE EXTENDED. TROUGH THAT IS OVR GREAT LAKES REGION ON TUE EVENTUALLY LIFTS TOWARD EASTERN CANADA/NORTHERN NEW ENGLAND BY LATE WEEK. TROUGH WILL STALL THOUGH AS IT MEETS BUILDING RIDGE OVR NORTHERN ATLANTIC INTO GREENLAND. RESULT IS THE TROUGH HOLDING OVR EASTERN CANADA AND ADJACENT GREAT LAKES. THE PATTERN SHOULD KEEP A PERSISTENT CHILL TO THE TEMPS OVR MUCH OF THE GREAT LAKES INTO NEW ENGLAND THOUGH EARLY NEXT WEEK. EXPECT DAYTIME AND NIGHTTIME TEMPS TO RANGE FM 5-10 DEGREES BLO NORMAL. NEXT CHANCE OF ANY PCPN SKIRTS THE AREA LATE FRIDAY INTO SATURDAY. 00Z ECMWF WAS THE STRONGEST WITH SFC LOW MOVING INTO MN ON SATURDAY AND HAD QPF INTO WESTERN CWA BY 00Z SAT. TONED THAT IDEA DOWN AS OTHER MODELS WERE WEAKER WITH THE TROUGH AND EASTWARD EXTENT OF PCPN. SINCE CENTER OF LARGE/DRY CANADIAN HIGH PRES REMAINS OVR ONTARIO INTO GREAT LAKES...IMAGINE MOST PCPN WILL BE DEFLECTED TO WEST AND SOUTH OF THE CWA FRIDAY NIGHT INTO SAT. SOME LGT PCPN IS POSSIBLE AS UPR LEVEL WAVE SLIDES THROUGH ON SUN BUT WITH SFC HIGH AND DRY AIR IN VCNTY WILL NOT INCLUDE ANY MENTION ATTM. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... SINCE SSE WINDS ARE SOMEWHAT DOWNSLOPING AT KCMX...VFR CONDITIONS SHOULD PREVAIL THERE THRU THE EVENING. HOWEVER...AREA OF -SN CURRENTLY OVER NW WI/FAR WRN UPPER MI MAY AFFECT KCMX...RESULTING IN PERIODIC MVFR CONDITIONS. AT KSAW...MVFR/IFR CIGS/VIS IN -SN SHOULD IMPROVE TO VFR LATER THIS EVENING AS DRIER AIR CURRENTLY OVER ERN WI LIFTS N. LATER IN THE NIGHT...DISTURBANCE APPROACHING FROM THE SW WILL CAUSE DEVELOPMENT OF WIDESPREAD -SN/FOG/IFR VSBYS AND CIGS WHICH WILL PERSIST THRU TUE MORNING. CONDITIONS WILL BE WORSE AT KSAW (DROPPING MORE FIRMLY INTO THE LIFR RANGE) DUE TO FAVORABLE UPSLOPING SE FLOW. PASSAGE OF SFC TROF AND RESULTING WIND SHIFT TO THE W OR NW WILL BRING IMPROVING CONDITIONS TO BOTH SITES TUE AFTN. BIGGEST IMPROVEMENT INITIALLY WILL BE WITH VIS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT A LOW NEAR HUDSON BAY TO DISSIPATE AS IT MOVES EASTWARD TONIGHT. ANOTHER LOW OVER SOUTHERN SASKATCHEWAN WILL DISSIPATE OVER NORTHWEST ONTARIO TUESDAY EVENING WHILE ANOTHER LOW PRESSURE SYSTEM GAINS STRENGTH OVER THE SOUTHERN PLAINS. THIS LOW WILL DEEPEN AS IT REACHES THE EASTERN GREAT LAKES WEDNESDAY EVENING. HIGH PRESSURE WILL THEN BUILD INTO THE NORTHERN PLAINS WEDNESDAY NIGHT AND THURSDAY MORNING. LOOK FOR THIS HIGH TO MOVE OVER THE UPPER GREAT LAKES THURSDAY AND REMAIN NEARLY STATIONARY THROUGH SATURDAY. THERE WILL BE NO GALES DURING THIS PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SYNOPSIS/SHORT TERM DISCUSSION...KC LONG TERM DISCUSSION...JLA AVIATION...ROLFSON MARINE...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 751 PM EDT MON MAR 17 2008 UPDATED AVIATION DISCUSSION FOR 00Z TAFS .SYNOPSIS... (ISSUED AT 400 PM EDT) 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW PATTERN ACRS NAMERICA. ZONAL ARCTIC BRANCH NOTED OVER SRN CAN WITH FAIRLY VIGOROUS SHRTWV/ASSOCIATED SFC LO MOVING INTO FAR NW ONTARIO. VIGOROUS SUBTROPICAL JET CUTOFF LO NOTED OVER THE DESERT SW WITH A PLUME OF TROPICAL MSTR STREAMING NNEWD ON THE HEELS OF SSW H85 WINDS UP TO 60KTS AT OKC INTO THE CNTRL CONUS FEEDING DEEP CONVECTION/HVY RA IN CNTRL PLAINS/MID MS RIVER VALLEY CLOSER TO ASSOCIATED H85 STNRY/WARM FNT. IN BTWN THESE BRANCHES...A POLAR BRANCH FLOW OBSVD ACRS THE NRN STATES WITH FAIRLY WELL DEFINED SHRTWV OVER THE NRN PLAINS. ALTHOUGH QUITE A BIT OF MID/HI CLD IN ADVANCE OF THIS FEATURE AND ANOTHER SHRTWV LIFTING NE FM CO OUT OF THE SUBTROPICAL BRANCH CUTOFF HAS SPILLED INTO THE UPR GRT LKS...12Z GRB/APX RAOBS AND TAMDAR SDNGS SHOW A VERY DRY MID TROP OVER THE AREA. WITH SFC-H85 ACYC FLOW EXTENDING WWD FM HI CENTER IN QUEBEC INTO THE UPR LKS...NO SN HAS FALLEN SO FAR TDAY OVER THE FA. BUT...12Z MPX SDNG SHOWS DEEP SFC-H3 MSTR...AND SOME -SN HAS BROKEN OUT IN NE MN/NW WI AHEAD OF THIS RETURNING MSTR. A HEAVIER BATCH OF PCPN IS NOW MOVING INTO IA/SW MN IN AREA OF SHARPER DPVA AHEAD OF SHRTWV LIFTING NE FM CO/RRQ OF H3 JET AXIS THAT EXTENDED FM LK SUP TO NEAR ABR AT 12Z. && .SHORT TERM (TNGT AND TUE)... (ISSUED AT 400 PM EDT) MAIN FORECAST CONCERNS DURING THIS PD IS PCPN COVG/TYPE/AMTS AND NEED FOR ANY HEADLINES. CONSIDERING THE RELIANCE OF THIS FCST ON THE INTERACTION OF THE VARIOUS BRANCHES DISCUSSED ABV...CONFIDENCE ON FCST EVOLUTION IS A BIT LOWER THAN EXPECTED FOR THIS SHORT TERM EVENT. FOR TNGT...GFS/NAM/LOCAL HI RES MODEL HAVE BEEN CONSISTENT SHOWING BAND OF -SN TO THE SW UNDER H4-2 DVGC IN RRQ OF JET AXIS DRIFTING ACRS THE FA THIS EVNG IN ADVANCE OF SHARPER DPVA/DEEP LYR H85-5 QVECTOR CNVGC FCST TO ARRIVE LATE TNGT AS SHRTWV NOW LIFTING NEWD FM CO MOVES TO SE MN BY 12Z TUE. WL GO WITH CHC POPS/SCT -SHSN THRU 06Z TO ACCOUNT FOR INITIAL WAVE OF -SN...THEN BUMP POPS UP TO CATEGORICAL AFT 06Z WITH ARRIVAL OF SHARPER DYNAMICS. ON TUE...SHRTWV IS FCST TO MOVE ACRS THE SE ZNS ARND 18Z AND INTO ONTARIO LATER IN THE DAY. EXPECT THE HIER QPF OVER THE W-CNTRL ON CYC SIDE OF THE TRACK OF THIS FEATURE...WITH MID LVL DRYING CUTTING DOWN ON THE PCPN TOTALS OVER THE SE. OTRW...EXPECT STEADY SN IN THE MRNG TO DIMINISH IN THE AFTN TO JUST SOME FLURRIES/-DZ WITH ARRIVAL OF DRIER AIR ALF AND IN LYRS WHERE THE TEMPS IS LOWER THAN -10C. NEITHER GFS/NAM FCST PROFILES SHOW FZRA/SLEET A LIKELY PCPN TYPE THRU THE EVENT. BEST CHC FOR THERE TO BE ANY PCPN TYPE BUT SN WL BE TUE AFTN WHEN TEMPS HAVE A CHC TO RECOVER FM SML DIURNAL TEMP FALL TNGT LIMITED BY WAD/ISENTROPIC LIFT. WL USE DZ TO COVER THAT PCPN TYPE WHEN MID LVL MSTR EXITS. AS FOR SN TOTALS...LOCAL HI RES MODEL SHOWS A FAIR AMT OF WATER EQUIVALENT PCPN (UP TO 0.40 INCH OR SO) FALLING OVER THE CNTRL ZNS DURING TUE MRNG ON CYC SIDE OF H5 VORT TRACK. CONSIDERING THE 3 G/KG SPECIFIC HUMIDITY NAM/GFS SHOW AVBL ON THE 290K SFC (H7-75)...THIS HI RES MODEL FCST DOES NOT APPEAR TOO OUT OF LINE. HOWEVER...SINCE THE CURRENT SHRTWV PLAYERS ARE OUT OF PHASE AND RICH TROPICAL MSTR WL BE INTERCEPTED ALG H85 WARM FNT WELL TO THE S...THINK SGNFT ADVY LEVEL PCPN IS UNLIKELY. ANOTHER NEGATIVE FOR HEAVY SN IS DGZ IS FCST TO BE ELEVATED AND RATHER NARROW IN DEPTH WITH INFLUX OF RELATIVELY WARM AIR BLO H7. LARGER SCALE MODELS (ESPECIALLY THE GFS) ALSO SHOW QUITE A BIT OF DRYING EVEN IN THE MRNG ABV H7. THIS FCST SEEMS A BIT UNREALISTIC OVER THE WCNTRL...WHICH WL BE IN BETTER POSITION RELATIVE TO THE VORT TRACK TO AVOID SGNFT DRYING ALF SO QUICKLY. IN ANY EVENT...WL NOT ISSUE ANY HEADLINES ATTM WITH PCPN/SN EFFICIENCY IN QUESTION. CONFIDENCE INCRSD BY LO NCEP FCST...WHICH SHOWS NO MORE THAN 2-3" THRU 00Z WED OVER THE WRN FA AND 1-2" OVER THE E. COORDINATED WITH APX/GRB/DLH. .LONG TERM (TUESDAY NIGHT THROUGH NEXT MONDAY)... LOW PRESSURE TROUGH IN PROCESS OF EXITING UPR MI ON TUESDAY EVENING. DRY AIR IN MID LEVELS CONTINUES TO ERODE CHANCES OF ANY APPRECIABLE PCPN. LOW CHANCE POPS WERE RETAINED OVER EASTERN ZONES TO ACCOUNT FOR ANY TIMING DIFFERENCES OF EXITING PCPN SHIELD. OTHERWISE... CHANCES OF PCPN ON TUE NIGHT INTO WED MORNING LOOK MEAGER. TEMPS IN WAKE OF THE TROUGH NOT ALL THAT COLD WITH H9-H85 TEMPS ONLY AS LOW AS -7C...AND THIS IS OFF THE COLDER GFS OUTPUT. MOIST LOWER LAYERS BENEATH DRY LAYER ALOFT AND WNW UPSLOPE FLOW COULD YIELD FREEZING DRIZZLE/FLURRIES OVER THE WEST PORTION OF CWA. H5 TROUGH SLIDES ACROSS UPR LAKES ON WED WITH H5 TEMPS BLO -30C AND H7 TEMPS TOWARD -20C. MOISTURE FM H85 TO H7 IS LACKING. HOWEVER... LOW LEVEL LAPSE RATES TO H85 NEAR 8C/KM...LOW CONVECTIVE TEMPS...AND A SHORTWAVE PUSHING THROUGH TO ACT AS A TRIGGER MAY ALLOW FOR CU AND INSTABILITY SNOW SHOWERS. ONCE TROUGH OVR GREAT LAKES DEPARTS...LOOK FOR WEATHER TO BE FAIRLY TRANQUIL INTO THE WEEKEND. 00Z ECMWF FIT ASSOCIATED ENSEMBLES FM GFS/CANADIAN THE BEST SO...LIKE HPC...FOR THE MOST PART...PREFERRED ECMWF SOLUTION THROUGH THE EXTENDED. TROUGH THAT IS OVR GREAT LAKES REGION ON TUE EVENTUALLY LIFTS TOWARD EASTERN CANADA/NORTHERN NEW ENGLAND BY LATE WEEK. TROUGH WILL STALL THOUGH AS IT MEETS BUILDING RIDGE OVR NORTHERN ATLANTIC INTO GREENLAND. RESULT IS THE TROUGH HOLDING OVR EASTERN CANADA AND ADJACENT GREAT LAKES. THE PATTERN SHOULD KEEP A PERSISTENT CHILL TO THE TEMPS OVR MUCH OF THE GREAT LAKES INTO NEW ENGLAND THOUGH EARLY NEXT WEEK. EXPECT DAYTIME AND NIGHTTIME TEMPS TO RANGE FM 5-10 DEGREES BLO NORMAL. NEXT CHANCE OF ANY PCPN SKIRTS THE AREA LATE FRIDAY INTO SATURDAY. 00Z ECMWF WAS THE STRONGEST WITH SFC LOW MOVING INTO MN ON SATURDAY AND HAD QPF INTO WESTERN CWA BY 00Z SAT. TONED THAT IDEA DOWN AS OTHER MODELS WERE WEAKER WITH THE TROUGH AND EASTWARD EXTENT OF PCPN. SINCE CENTER OF LARGE/DRY CANADIAN HIGH PRES REMAINS OVR ONTARIO INTO GREAT LAKES...IMAGINE MOST PCPN WILL BE DEFLECTED TO WEST AND SOUTH OF THE CWA FRIDAY NIGHT INTO SAT. SOME LGT PCPN IS POSSIBLE AS UPR LEVEL WAVE SLIDES THROUGH ON SUN BUT WITH SFC HIGH AND DRY AIR IN VCNTY WILL NOT INCLUDE ANY MENTION ATTM. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... SINCE SSE WINDS ARE SOMEWHAT DOWNSLOPING AT KCMX...VFR CONDITIONS SHOULD PREVAIL THERE THRU THE EVENING. HOWEVER...AREA OF -SN CURRENTLY OVER NW WI/FAR WRN UPPER MI MAY AFFECT KCMX...RESULTING IN PERIODIC MVFR CONDITIONS. AT KSAW...MVFR/IFR CIGS/VIS IN -SN SHOULD IMPROVE TO VFR LATER THIS EVENING AS DRIER AIR CURRENTLY OVER ERN WI LIFTS N. LATER IN THE NIGHT...DISTURBANCE APPROACHING FROM THE SW WILL CAUSE DEVELOPMENT OF WIDESPREAD -SN/FOG/IFR VSBYS AND CIGS WHICH WILL PERSIST THRU TUE MORNING. CONDITIONS WILL BE WORSE AT KSAW (DROPPING MORE FIRMLY INTO THE LIFR RANGE) DUE TO FAVORABLE UPSLOPING SE FLOW. PASSAGE OF SFC TROF AND RESULTING WIND SHIFT TO THE W OR NW WILL BRING IMPROVING CONDITIONS TO BOTH SITES TUE AFTN. BIGGEST IMPROVEMENT INITIALLY WILL BE WITH VIS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT A LOW NEAR HUDSON BAY TO DISSIPATE AS IT MOVES EASTWARD TONIGHT. ANOTHER LOW OVER SOUTHERN SASKATCHEWAN WILL DISSIPATE OVER NORTHWEST ONTARIO TUESDAY EVENING WHILE ANOTHER LOW PRESSURE SYSTEM GAINS STRENGTH OVER THE SOUTHERN PLAINS. THIS LOW WILL DEEPEN AS IT REACHES THE EASTERN GREAT LAKES WEDNESDAY EVENING. HIGH PRESSURE WILL THEN BUILD INTO THE NORTHERN PLAINS WEDNESDAY NIGHT AND THURSDAY MORNING. LOOK FOR THIS HIGH TO MOVE OVER THE UPPER GREAT LAKES THURSDAY AND REMAIN NEARLY STATIONARY THROUGH SATURDAY. THERE WILL BE NO GALES DURING THIS PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM DISCUSSION...KC LONG TERM DISCUSSION...JLA AVIATION...ROLFSON MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 PM EDT MON MAR 17 2008 .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW PATTERN ACRS NAMERICA. ZONAL ARCTIC BRANCH NOTED OVER SRN CAN WITH FAIRLY VIGOROUS SHRTWV/ASSOCIATED SFC LO MOVING INTO FAR NW ONTARIO. VIGOROUS SUBTROPICAL JET CUTOFF LO NOTED OVER THE DESERT SW WITH A PLUME OF TROPICAL MSTR STREAMING NNEWD ON THE HEELS OF SSW H85 WINDS UP TO 60KTS AT OKC INTO THE CNTRL CONUS FEEDING DEEP CONVECTION/HVY RA IN CNTRL PLAINS/MID MS RIVER VALLEY CLOSER TO ASSOCIATED H85 STNRY/WARM FNT. IN BTWN THESE BRANCHES...A POLAR BRANCH FLOW OBSVD ACRS THE NRN STATES WITH FAIRLY WELL DEFINED SHRTWV OVER THE NRN PLAINS. ALTHOUGH QUITE A BIT OF MID/HI CLD IN ADVANCE OF THIS FEATURE AND ANOTHER SHRTWV LIFTING NE FM CO OUT OF THE SUBTROPICAL BRANCH CUTOFF HAS SPILLED INTO THE UPR GRT LKS...12Z GRB/APX RAOBS AND TAMDAR SDNGS SHOW A VERY DRY MID TROP OVER THE AREA. WITH SFC-H85 ACYC FLOW EXTENDING WWD FM HI CENTER IN QUEBEC INTO THE UPR LKS...NO SN HAS FALLEN SO FAR TDAY OVER THE FA. BUT...12Z MPX SDNG SHOWS DEEP SFC-H3 MSTR...AND SOME -SN HAS BROKEN OUT IN NE MN/NW WI AHEAD OF THIS RETURNING MSTR. A HEAVIER BATCH OF PCPN IS NOW MOVING INTO IA/SW MN IN AREA OF SHARPER DPVA AHEAD OF SHRTWV LIFTING NE FM CO/RRQ OF H3 JET AXIS THAT EXTENDED FM LK SUP TO NEAR ABR AT 12Z. && .SHORT TERM DISCUSSION (TNGT AND TUE)... MAIN FORECAST CONCERNS DURING THIS PD IS PCPN COVG/TYPE/AMTS AND NEED FOR ANY HEADLINES. CONSIDERING THE RELIANCE OF THIS FCST ON THE INTERACTION OF THE VARIOUS BRANCHES DISCUSSED ABV...CONFIDENCE ON FCST EVOLUTION IS A BIT LOWER THAN EXPECTED FOR THIS SHORT TERM EVENT. FOR TNGT...GFS/NAM/LOCAL HI RES MODEL HAVE BEEN CONSISTENT SHOWING BAND OF -SN TO THE SW UNDER H4-2 DVGC IN RRQ OF JET AXIS DRIFTING ACRS THE FA THIS EVNG IN ADVANCE OF SHARPER DPVA/DEEP LYR H85-5 QVECTOR CNVGC FCST TO ARRIVE LATE TNGT AS SHRTWV NOW LIFTING NEWD FM CO MOVES TO SE MN BY 12Z TUE. WL GO WITH CHC POPS/SCT -SHSN THRU 06Z TO ACCOUNT FOR INITIAL WAVE OF -SN...THEN BUMP POPS UP TO CATEGORICAL AFT 06Z WITH ARRIVAL OF SHARPER DYNAMICS. ON TUE...SHRTWV IS FCST TO MOVE ACRS THE SE ZNS ARND 18Z AND INTO ONTARIO LATER IN THE DAY. EXPECT THE HIER QPF OVER THE W-CNTRL ON CYC SIDE OF THE TRACK OF THIS FEATURE...WITH MID LVL DRYING CUTTING DOWN ON THE PCPN TOTALS OVER THE SE. OTRW...EXPECT STEADY SN IN THE MRNG TO DIMINISH IN THE AFTN TO JUST SOME FLURRIES/-DZ WITH ARRIVAL OF DRIER AIR ALF AND IN LYRS WHERE THE TEMPS IS LOWER THAN -10C. NEITHER GFS/NAM FCST PROFILES SHOW FZRA/SLEET A LIKELY PCPN TYPE THRU THE EVENT. BEST CHC FOR THERE TO BE ANY PCPN TYPE BUT SN WL BE TUE AFTN WHEN TEMPS HAVE A CHC TO RECOVER FM SML DIURNAL TEMP FALL TNGT LIMITED BY WAD/ISENTROPIC LIFT. WL USE DZ TO COVER THAT PCPN TYPE WHEN MID LVL MSTR EXITS. AS FOR SN TOTALS...LOCAL HI RES MODEL SHOWS A FAIR AMT OF WATER EQUIVALENT PCPN (UP TO 0.40 INCH OR SO) FALLING OVER THE CNTRL ZNS DURING TUE MRNG ON CYC SIDE OF H5 VORT TRACK. CONSIDERING THE 3 G/KG SPECIFIC HUMIDITY NAM/GFS SHOW AVBL ON THE 290K SFC (H7-75)...THIS HI RES MODEL FCST DOES NOT APPEAR TOO OUT OF LINE. HOWEVER...SINCE THE CURRENT SHRTWV PLAYERS ARE OUT OF PHASE AND RICH TROPICAL MSTR WL BE INTERCEPTED ALG H85 WARM FNT WELL TO THE S...THINK SGNFT ADVY LEVEL PCPN IS UNLIKELY. ANOTHER NEGATIVE FOR HEAVY SN IS DGZ IS FCST TO BE ELEVATED AND RATHER NARROW IN DEPTH WITH INFLUX OF RELATIVELY WARM AIR BLO H7. LARGER SCALE MODELS (ESPECIALLY THE GFS) ALSO SHOW QUITE A BIT OF DRYING EVEN IN THE MRNG ABV H7. THIS FCST SEEMS A BIT UNREALISTIC OVER THE WCNTRL...WHICH WL BE IN BETTER POSITION RELATIVE TO THE VORT TRACK TO AVOID SGNFT DRYING ALF SO QUICKLY. IN ANY EVENT...WL NOT ISSUE ANY HEADLINES ATTM WITH PCPN/SN EFFICIENCY IN QUESTION. CONFIDENCE INCRSD BY LO NCEP FCST...WHICH SHOWS NO MORE THAN 2-3" THRU 00Z WED OVER THE WRN FA AND 1-2" OVER THE E. COORDINATED WITH APX/GRB/DLH. .LONG TERM DISCUSSION (TUESDAY NIGHT THROUGH NEXT MONDAY)... LOW PRESSURE TROUGH IN PROCESS OF EXITING UPR MI ON TUESDAY EVENING. DRY AIR IN MID LEVELS CONTINUES TO ERODE CHANCES OF ANY APPRECIABLE PCPN. LOW CHANCE POPS WERE RETAINED OVER EASTERN ZONES TO ACCOUNT FOR ANY TIMING DIFFERENCES OF EXITING PCPN SHIELD. OTHERWISE... CHANCES OF PCPN ON TUE NIGHT INTO WED MORNING LOOK MEAGER. TEMPS IN WAKE OF THE TROUGH NOT ALL THAT COLD WITH H9-H85 TEMPS ONLY AS LOW AS -7C...AND THIS IS OFF THE COLDER GFS OUTPUT. MOIST LOWER LAYERS BENEATH DRY LAYER ALOFT AND WNW UPSLOPE FLOW COULD YIELD FREEZING DRIZZLE/FLURRIES OVER THE WEST PORTION OF CWA. H5 TROUGH SLIDES ACROSS UPR LAKES ON WED WITH H5 TEMPS BLO -30C AND H7 TEMPS TOWARD -20C. MOISTURE FM H85 TO H7 IS LACKING. HOWEVER... LOW LEVEL LAPSE RATES TO H85 NEAR 8C/KM...LOW CONVECTIVE TEMPS...AND A SHORTWAVE PUSHING THROUGH TO ACT AS A TRIGGER MAY ALLOW FOR CU AND INSTABILITY SNOW SHOWERS. ONCE TROUGH OVR GREAT LAKES DEPARTS...LOOK FOR WEATHER TO BE FAIRLY TRANQUIL INTO THE WEEKEND. 00Z ECMWF FIT ASSOCIATED ENSEMBLES FM GFS/CANADIAN THE BEST SO...LIKE HPC...FOR THE MOST PART...PREFERRED ECMWF SOLUTION THROUGH THE EXTENDED. TROUGH THAT IS OVR GREAT LAKES REGION ON TUE EVENTUALLY LIFTS TOWARD EASTERN CANADA/NORTHERN NEW ENGLAND BY LATE WEEK. TROUGH WILL STALL THOUGH AS IT MEETS BUILDING RIDGE OVR NORTHERN ATLANTIC INTO GREENLAND. RESULT IS THE TROUGH HOLDING OVR EASTERN CANADA AND ADJACENT GREAT LAKES. THE PATTERN SHOULD KEEP A PERSISTENT CHILL TO THE TEMPS OVR MUCH OF THE GREAT LAKES INTO NEW ENGLAND THOUGH EARLY NEXT WEEK. EXPECT DAYTIME AND NIGHTTIME TEMPS TO RANGE FM 5-10 DEGREES BLO NORMAL. NEXT CHANCE OF ANY PCPN SKIRTS THE AREA LATE FRIDAY INTO SATURDAY. 00Z ECMWF WAS THE STRONGEST WITH SFC LOW MOVING INTO MN ON SATURDAY AND HAD QPF INTO WESTERN CWA BY 00Z SAT. TONED THAT IDEA DOWN AS OTHER MODELS WERE WEAKER WITH THE TROUGH AND EASTWARD EXTENT OF PCPN. SINCE CENTER OF LARGE/DRY CANADIAN HIGH PRES REMAINS OVR ONTARIO INTO GREAT LAKES...IMAGINE MOST PCPN WILL BE DEFLECTED TO WEST AND SOUTH OF THE CWA FRIDAY NIGHT INTO SAT. SOME LGT PCPN IS POSSIBLE AS UPR LEVEL WAVE SLIDES THROUGH ON SUN BUT WITH SFC HIGH AND DRY AIR IN VCNTY WILL NOT INCLUDE ANY MENTION ATTM. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... LLVL MSTR SHOWN ON THE 12Z GRB RAOB AND INDICATED BY HIER DWPTS NR LK MI HAS STREAMED N INTO THE CNTRL CWA AND CAUSED TEMPO LO MVFR SC CIG TO DVLP AT SAW WITH FVRBL UPSLOPE SLY FLOW. DOWNSLOPE NATURE OF THE FLOW AT CMX HAS PREVENTED THE DVLPMNT OF THIS CIG THERE. WITH PERSISTENT SSE FLOW THRU THIS EVNG...EXPECT MVFR CIG TO PREDOMINATE AT SAW WITH VFR CONDITIONS AT CMX. APRCH OF DISTURBANCE FM THE SW LATE TNGT WL CAUSE DVLPMNT OF WDSPRD -SN/FOG/IFR VSBYS AND CIGS AFT MIDNGT THRU TUE MRNG. CONDITIONS WL BE WORSE AT SAW WITH FVRBL SE FLOW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT A LOW NEAR HUDSON BAY TO DISSIPATE AS IT MOVES EASTWARD TONIGHT. ANOTHER LOW OVER SOUTHERN SASKATCHEWAN WILL DISSIPATE OVER NORTHWEST ONTARIO TUESDAY EVENING WHILE ANOTHER LOW PRESSURE SYSTEM GAINS STRENGTH OVER THE SOUTHERN PLAINS. THIS LOW WILL DEEPEN AS IT REACHES THE EASTERN GREAT LAKES WEDNESDAY EVENING. HIGH PRESSURE WILL THEN BUILD INTO THE NORTHERN PLAINS WEDNESDAY NIGHT AND THURSDAY MORNING. LOOK FOR THIS HIGH TO MOVE OVER THE UPPER GREAT LAKES THURSDAY AND REMAIN NEARLY STATIONARY THROUGH SATURDAY. THERE WILL BE NO GALES DURING THIS PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM DISCUSSION...KC LONG TERM DISCUSSION...JLA AVIATION...KC MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 125 PM EDT MON MAR 17 2008 UPDATED FOR AVIATION .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED SPLIT FLOW ACROSS NORTH AMERICA. WITHIN THE NORTHERN STREAM...WHICH IS MOSTLY ZONAL ACROSS SOUTHERN CANADA...THERE IS A SHRTWV TROUGH MOVING INTO WESTERN MANITOBA. SOME MID AND HIGH CLOUDS EXIST WITH THIS SHRTWV OVER MANITOBA...ALONG WITH A 1004 MB SURFACE LOW ON THE NORTH END OF LAKE WINNIPEG. IN THE SOUTHERN STREAM...AN UPPER TROUGH STRETCHED FROM THE FOUR CORNERS INTO BAJA CALIFORNIA...WITH RIDGING DOWNSTREAM INTO THE MISSOURI AND OHIO VALLEYS. NUMEROUS SHRTWVS ARE LOCATED WITHIN THE UPPER TROUGH...BUT THE MOST IMPORTANT ONE FOR THIS FORECAST IS LOCATED IN SW NEW MEXICO. ON WATER VAPOR...A SUBTROPICAL JET CAN BE SEEN AHEAD OF THIS TROUGH...WITH MOISTURE STREAMING FROM THE DEEP TROPICS OF THE EAST PACIFIC INTO THE CENTRAL PLAINS. IR IMAGERY REFLECTS THE MOISTURE WITH PLENTY OF CLOUDS FROM THE CENTRAL PLAINS UP INTO WISCONSIN. RUC ANALYSIS ALSO SHOWS A STRONG UPPER JET AROUND 200MB FROM WESTERN KS AND NEBRASKA EASTWARD TO PENNSYLVANIA (SPEEDS UP TO 160 KT). GIVEN THE POSITION OF THE UPPER TROUGH OVER THE SOUTHWEST U.S....A LOW LEVEL JET HAS DEVELOPED OVER THE CENTRAL AND SOUTHERN PLAINS. PROFILERS IN THIS AREA AT 850MB SHOW WINDS OUT OF THE SOUTH TO SE AT 50-75 KT...PULLING MOISTURE OUT OF THE GULF OF MEXICO. HOWEVER...IT SHOULD BE NOTED THAT 850MB MOISTURE WAS STILL LACKING AT 00Z AT OKC AND FWD WITH DEWPOINT DEPRESSIONS OF 5-10C. MUCH MORE MOISTURE WAS PRESENT NEAR THE GULF COAST AT CRP AND BRO... WHICH GIVEN THE STRENGTH OF THE WIND SHOULD BE MAKING ITS WAY UP INTO OKLAHOMA BY NOW. CLOSER TO HOME...THE AREA REMAINS UNDER THE INFLUENCE OF A 1036 MB SURFACE HIGH SITUATED OVER NE ONTARIO. DRY AIR...SEEN ON THE 00Z SOUNDINGS FROM APX AND GRB...ALONG WITH LIGHT WINDS AND CLEAR SKIES FOR MUCH OF THE NIGHT HAVE ALLOWED INLAND TEMPS TO GET CHILLY...ESPECIALLY IN THE EASTERN U.P.. HOWEVER... HIGH CLOUDS FROM THE SUBTROPICAL JET ARE STARTING TO MOVE INTO THE CWA. && .DISCUSSION... MAIN FORECAST CONCERN IS PCPN AND TYPE FOR TONIGHT AND TUESDAY. TODAY...DRY LOW LEVEL AIR ON THE 00Z APX AND GRB SOUNDINGS WILL BE THE MAIN ISSUE FOR FIGURING OUT WHETHER PCPN OCCURS. MODELS DEPICT THE SHRTWV TROUGH OVER MANITOBA TO LIFT UP TO HUDSON BAY...STAYING FAR ENOUGH AWAY FROM HERE THAT THE ONLY FACTOR WILL BE PUSHING THE SURFACE HIGH OVER EASTERN ONTARIO INTO QUEBEC. THEREFORE AN INCREASE IN SOUTHERLY WINDS IS LIKELY TODAY. TO OUR SW...THE SHRTWV OVER NEW MEXICO IS PROGGED TO LIFT INTO NE COLORADO. DPVA DOWNSTREAM OF THE SHRTWV ALONG WITH WARM ADVECTION SHOULD ALLOW EXPANSION OF THE CURRENT PCPN ACROSS NEBRASKA AND IOWA INTO SOUTHERN MN...NW WI AND EVENTUALLY WESTERN UPPER MI LATE IN THE AFTERNOON. LIKE THE LATE TIMING GIVEN THE CURRENT DRY AIR. HAVE ADJUSTED THE GRIDS FOR A SLOWER ARRIVAL OF PCPN CHANCES. ANY PCPN THAT DOES FALL LOOKS TO BE MINIMAL...GIVEN THE DRY AIR...AND MODEL QPF FIELDS REFLECT THIS WITH ONLY A HUNDREDTH OR TWO AT MOST. ALTHOUGH PCPN IS MINIMAL TODAY... LOOK FOR CLOUD COVER TO BE ON THE INCREASE...WITH CEILINGS GRADUALLY LOWERING THROUGH THE DAY. THESE CLOUDS WILL PREVENT SURFACE HEATING FROM THE SUN...BUT THE INCREASING WINDS SHOULD HELP IN BRINGING WARMER AIR NORTHWARD. PREVIOUS FORECAST HIGHS LOOK GOOD AND ONLY SLIGHT TWEAKS MADE. TONIGHT AND TUESDAY...SHRTWV OVER NE COLORADO LIFTS UP INTO SRN MN BY 12Z TUE...OVER THE CWA AT 18Z TUE AND INTO NE ONTARIO BY 00Z WED. CONTINUED DPVA AHEAD OF THIS SHRWTV ALONG WITH ISENTROPIC LIFT/MID-LEVEL FRONTOGENESIS WILL HELP TO BRING MORE PCPN INTO THE AREA...WITH THE MAJORITY OF IT OCCURRING DURING THE 06Z-18Z TUE TIMEFRAME WHEN THE SHRTWV IS APPROACHING. THERE IS ONE MAJOR ISSUE WITH REGARDS TO QPF AMOUNTS AND THAT IS A LOT OF THE GULF OF MEXICO MOISTURE IS GOING TO GET INTERCEPTED NEAR THE OHIO RIVER VALLEY... DOWN NEAR THE MAIN WARM FRONTAL BOUNDARY AND UPPER LEVEL DIVERGENCE AREA. MOST MODELS HAVE RESPONDED BY HAVING LESS QPF THAN PREVIOUSLY FORECASTED...WITH GENERAL AMOUNTS DURING THE 06-18Z TIME FRAME MENTIONED ABOVE IN THE 0.25 TO 0.40 OF AN INCH RANGE. WARMER AIR WILL STILL GET PULLED UP INTO THE AREA...ESPECIALLY IN THE REGIONAL CANADIAN MODEL...MEANING A DEEP AGGREGATION ZONE TO HELP REDUCE SNOW TO WATER RATIOS (LIKELY AROUND OR JUST BELOW 10 TO 1). PCPN ALONG LAKE MI IN THE LATEST NAM AND GFS WOULD STAY MAINLY AS SNOW...BUT WITH THE REGIONAL CANADIAN DRAWING WARMER AIR IN AND TO MAINTAIN SOME CONTINUITY WITH PREVIOUS FORECASTS...HAVE DECIDED TO KEEP A MENTION OF SOME RAIN. THERE COULD BE FREEZING RAIN OR SLEET ALONG LAKE MI...BUT WITH THE MAJORITY OF THE MODELS MAINTAIN A THERMODYNAMIC PROFILE BELOW FREEZING FOR THE BULK OF THE PCPN... HAVE WENT WITH EITHER RAIN OR SNOW. LATER FORECASTS CAN REFINE FOR REMOVAL OF RAIN...OR INCLUSION OF FREEZING RAIN AND SLEET IF NECESSARY. AS FAR AS THE HEADLINE ISSUE...EVENT NOW LOOKS MORE LIKE A MARGINAL ADVISORY...BUT GIVEN THE LOW SNOW TO WATER RATIOS...AN ADVISORY FOR AT LEAST THE WEST HALF OF UPPER MI WILL LIKELY BE NEEDED. HOWEVER...SINCE THE EVENT REALLY DOES NOT GET GOING UNTIL AFTER MIDNIGHT TONIGHT...HAVE DECIDED NOT TO ISSUE THE ADVISORY YET. WILL UPDATE THE SPS...THOUGH. LAST ITEM TO NOTE IS THAT IT APPEARS IN THE WAKE OF THE SHRTWV...THE MID LEVELS WILL DRY OUT...CAUSING THE -10C ISOTHERM TO BECOME UNSATURATED. THEREFORE...HAVE INCLUDED A MENTION OF DRIZZLE FOR THE WEST HALF OF UPPER MI. LOW AND HIGH TEMPS DURING THIS PERIOD LOOK REASONABLE. TUESDAY NIGHT THROUGH THURSDAY...MAJORITY OF THIS PERIOD IS FAIRLY QUIET. NORTHERN STREAM UPPER TROUGH SITUATED OVER THE NORTHERN PLAINS AT 00Z WED IS PROGGED TO SHIFT OVER THE GREAT LAKES ON WED...THEN AMPLIFY WED NIGHT AND THU AS THE SOUTHERN STREAM UPPER LOW PHASES WITH THIS TROUGH. SOME COLDER AIR ADVECTS IN TUE NIGHT AND WED...BUT 850MB TEMPS DO NOT FALL BELOW -10C...SUGGESTING LAKE EFFECT POTENTIAL IS MINIMAL. HOWEVER...SOME UPSLOPE PCPN IS POSSIBLE IN NW FLOW AREAS ON TUE NIGHT...WITH DIURNAL SNOW SHOWER ACTIVITY ON WED UNDER THE UPPER TROUGH. COLDER AIR...PERHAPS WITH 850MB TEMPS FALLING TO -10 TO -12C IS INDICATED TO FLOW IN WED NIGHT AND THU AS THE UPPER TROUGH AMPLIFIES...WHICH COULD GET SOME LAKE EFFECT SNOW GOING. HOWEVER...A RIDGE OF CANADIAN HIGH PRESSURE IS PROGGED TO BUILD IN THU AFTERNOON INTO WESTERN LAKE SUPERIOR...AND THE COMBINATION OF DAYTIME HEATING AND DRY AIR FROM THIS RIDGE SHOULD END ANY LAKE EFFECT OVER THE WEST HALF OF UPPER MI. ALTHOUGH THE AIR IS COLDER THAN TODAY AND TUESDAY...THE AIR IS BETTER FOR MIXING... ESPECIALLY DURING THE DAYTIME. THUS HAVE WENT WITH HIGHS SIMILAR TO TODAY AND TUESDAY...AND THOSE AREAS IN NW DOWNSLOPE LIKE MNM COULD ACTUALLY END UP BEING WARMER. BEYOND THURSDAY...THE ONLY CHANGE MADE TO THE FORECAST WAS TO LOWER LOWS FOR THU NIGHT WITH THE DRY CANADIAN HIGH PRESSURE RIDGE OVERHEAD. THESE LOWS MAY NEED TO BE DROPPED EVEN MORE. DRY FORECAST STILL LOOKS GOOD INTO FRIDAY...AND COULD BE DRIED OUT INTO SATURDAY WITH THE HIGH PRESSURE RIDGE REMAINING IN PLACE PER THE 00Z ECMWF/GFS. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... LLVL MSTR SHOWN ON THE 12Z GRB RAOB AND INDICATED BY HIER DWPTS NR LK MI HAS STREAMED N INTO THE CNTRL CWA AND CAUSED TEMPO LO MVFR SC CIG TO DVLP AT SAW WITH FVRBL UPSLOPE SLY FLOW. DOWNSLOPE NATURE OF THE FLOW AT CMX HAS PREVENTED THE DVLPMNT OF THIS CIG THERE. WITH PERSISTENT SSE FLOW THRU THIS EVNG...EXPECT MVFR CIG TO PREDOMINATE AT SAW WITH VFR CONDITIONS AT CMX. APRCH OF DISTURBANCE FM THE SW LATE TNGT WL CAUSE DVLPMNT OF WDSPRD -SN/FOG/IFR VSBYS AND CIGS AFT MIDNGT THRU TUE MRNG. CONDITIONS WL BE WORSE AT SAW WITH FVRBL SE FLOW. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NO GALES SEEN ANYTIME SOON. WENT WITH THE NAM SOLUTION WHICH HAD WEAKER WINDS FOR WED ONWARD AND THEN THE GFS SOLUTION WHICH WAS CLOSE TO THE ECMWF SOLUTION. THE GFS SOLUTION WAS AN OUTLIER WITH ITS STRONGER WINDS AND DID NOT USE. WINDS STAY BELOW 25 KNOTS THE ENTIRE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...KC MARINE...GJM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 709 AM EDT MON MAR 17 2008 .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED SPLIT FLOW ACROSS NORTH AMERICA. WITHIN THE NORTHERN STREAM...WHICH IS MOSTLY ZONAL ACROSS SOUTHERN CANADA...THERE IS A SHRTWV TROUGH MOVING INTO WESTERN MANITOBA. SOME MID AND HIGH CLOUDS EXIST WITH THIS SHRTWV OVER MANITOBA...ALONG WITH A 1004 MB SURFACE LOW ON THE NORTH END OF LAKE WINNIPEG. IN THE SOUTHERN STREAM...AN UPPER TROUGH STRETCHED FROM THE FOUR CORNERS INTO BAJA CALIFORNIA...WITH RIDGING DOWNSTREAM INTO THE MISSOURI AND OHIO VALLEYS. NUMEROUS SHRTWVS ARE LOCATED WITHIN THE UPPER TROUGH...BUT THE MOST IMPORTANT ONE FOR THIS FORECAST IS LOCATED IN SW NEW MEXICO. ON WATER VAPOR...A SUBTROPICAL JET CAN BE SEEN AHEAD OF THIS TROUGH...WITH MOISTURE STREAMING FROM THE DEEP TROPICS OF THE EAST PACIFIC INTO THE CENTRAL PLAINS. IR IMAGERY REFLECTS THE MOISTURE WITH PLENTY OF CLOUDS FROM THE CENTRAL PLAINS UP INTO WISCONSIN. RUC ANALYSIS ALSO SHOWS A STRONG UPPER JET AROUND 200MB FROM WESTERN KS AND NEBRASKA EASTWARD TO PENNSYLVANIA (SPEEDS UP TO 160 KT). GIVEN THE POSITION OF THE UPPER TROUGH OVER THE SOUTHWEST U.S....A LOW LEVEL JET HAS DEVELOPED OVER THE CENTRAL AND SOUTHERN PLAINS. PROFILERS IN THIS AREA AT 850MB SHOW WINDS OUT OF THE SOUTH TO SE AT 50-75 KT...PULLING MOISTURE OUT OF THE GULF OF MEXICO. HOWEVER...IT SHOULD BE NOTED THAT 850MB MOISTURE WAS STILL LACKING AT 00Z AT OKC AND FWD WITH DEWPOINT DEPRESSIONS OF 5-10C. MUCH MORE MOISTURE WAS PRESENT NEAR THE GULF COAST AT CRP AND BRO... WHICH GIVEN THE STRENGTH OF THE WIND SHOULD BE MAKING ITS WAY UP INTO OKLAHOMA BY NOW. CLOSER TO HOME...THE AREA REMAINS UNDER THE INFLUENCE OF A 1036 MB SURFACE HIGH SITUATED OVER NE ONTARIO. DRY AIR...SEEN ON THE 00Z SOUNDINGS FROM APX AND GRB...ALONG WITH LIGHT WINDS AND CLEAR SKIES FOR MUCH OF THE NIGHT HAVE ALLOWED INLAND TEMPS TO GET CHILLY...ESPECIALLY IN THE EASTERN U.P.. HOWEVER... HIGH CLOUDS FROM THE SUBTROPICAL JET ARE STARTING TO MOVE INTO THE CWA. && .DISCUSSION... MAIN FORECAST CONCERN IS PCPN AND TYPE FOR TONIGHT AND TUESDAY. TODAY...DRY LOW LEVEL AIR ON THE 00Z APX AND GRB SOUNDINGS WILL BE THE MAIN ISSUE FOR FIGURING OUT WHETHER PCPN OCCURS. MODELS DEPICT THE SHRTWV TROUGH OVER MANITOBA TO LIFT UP TO HUDSON BAY...STAYING FAR ENOUGH AWAY FROM HERE THAT THE ONLY FACTOR WILL BE PUSHING THE SURFACE HIGH OVER EASTERN ONTARIO INTO QUEBEC. THEREFORE AN INCREASE IN SOUTHERLY WINDS IS LIKELY TODAY. TO OUR SW...THE SHRTWV OVER NEW MEXICO IS PROGGED TO LIFT INTO NE COLORADO. DPVA DOWNSTREAM OF THE SHRTWV ALONG WITH WARM ADVECTION SHOULD ALLOW EXPANSION OF THE CURRENT PCPN ACROSS NEBRASKA AND IOWA INTO SOUTHERN MN...NW WI AND EVENTUALLY WESTERN UPPER MI LATE IN THE AFTERNOON. LIKE THE LATE TIMING GIVEN THE CURRENT DRY AIR. HAVE ADJUSTED THE GRIDS FOR A SLOWER ARRIVAL OF PCPN CHANCES. ANY PCPN THAT DOES FALL LOOKS TO BE MINIMAL...GIVEN THE DRY AIR...AND MODEL QPF FIELDS REFLECT THIS WITH ONLY A HUNDREDTH OR TWO AT MOST. ALTHOUGH PCPN IS MINIMAL TODAY... LOOK FOR CLOUD COVER TO BE ON THE INCREASE...WITH CEILINGS GRADUALLY LOWERING THROUGH THE DAY. THESE CLOUDS WILL PREVENT SURFACE HEATING FROM THE SUN...BUT THE INCREASING WINDS SHOULD HELP IN BRINGING WARMER AIR NORTHWARD. PREVIOUS FORECAST HIGHS LOOK GOOD AND ONLY SLIGHT TWEAKS MADE. TONIGHT AND TUESDAY...SHRTWV OVER NE COLORADO LIFTS UP INTO SRN MN BY 12Z TUE...OVER THE CWA AT 18Z TUE AND INTO NE ONTARIO BY 00Z WED. CONTINUED DPVA AHEAD OF THIS SHRWTV ALONG WITH ISENTROPIC LIFT/MID-LEVEL FRONTOGENESIS WILL HELP TO BRING MORE PCPN INTO THE AREA...WITH THE MAJORITY OF IT OCCURRING DURING THE 06Z-18Z TUE TIMEFRAME WHEN THE SHRTWV IS APPROACHING. THERE IS ONE MAJOR ISSUE WITH REGARDS TO QPF AMOUNTS AND THAT IS A LOT OF THE GULF OF MEXICO MOISTURE IS GOING TO GET INTERCEPTED NEAR THE OHIO RIVER VALLEY... DOWN NEAR THE MAIN WARM FRONTAL BOUNDARY AND UPPER LEVEL DIVERGENCE AREA. MOST MODELS HAVE RESPONDED BY HAVING LESS QPF THAN PREVIOUSLY FORECASTED...WITH GENERAL AMOUNTS DURING THE 06-18Z TIME FRAME MENTIONED ABOVE IN THE 0.25 TO 0.40 OF AN INCH RANGE. WARMER AIR WILL STILL GET PULLED UP INTO THE AREA...ESPECIALLY IN THE REGIONAL CANADIAN MODEL...MEANING A DEEP AGGREGATION ZONE TO HELP REDUCE SNOW TO WATER RATIOS (LIKELY AROUND OR JUST BELOW 10 TO 1). PCPN ALONG LAKE MI IN THE LATEST NAM AND GFS WOULD STAY MAINLY AS SNOW...BUT WITH THE REGIONAL CANADIAN DRAWING WARMER AIR IN AND TO MAINTAIN SOME CONTINUITY WITH PREVIOUS FORECASTS...HAVE DECIDED TO KEEP A MENTION OF SOME RAIN. THERE COULD BE FREEZING RAIN OR SLEET ALONG LAKE MI...BUT WITH THE MAJORITY OF THE MODELS MAINTAIN A THERMODYNAMIC PROFILE BELOW FREEZING FOR THE BULK OF THE PCPN... HAVE WENT WITH EITHER RAIN OR SNOW. LATER FORECASTS CAN REFINE FOR REMOVAL OF RAIN...OR INCLUSION OF FREEZING RAIN AND SLEET IF NECESSARY. AS FAR AS THE HEADLINE ISSUE...EVENT NOW LOOKS MORE LIKE A MARGINAL ADVISORY...BUT GIVEN THE LOW SNOW TO WATER RATIOS...AN ADVISORY FOR AT LEAST THE WEST HALF OF UPPER MI WILL LIKELY BE NEEDED. HOWEVER...SINCE THE EVENT REALLY DOES NOT GET GOING UNTIL AFTER MIDNIGHT TONIGHT...HAVE DECIDED NOT TO ISSUE THE ADVISORY YET. WILL UPDATE THE SPS...THOUGH. LAST ITEM TO NOTE IS THAT IT APPEARS IN THE WAKE OF THE SHRTWV...THE MID LEVELS WILL DRY OUT...CAUSING THE -10C ISOTHERM TO BECOME UNSATURATED. THEREFORE...HAVE INCLUDED A MENTION OF DRIZZLE FOR THE WEST HALF OF UPPER MI. LOW AND HIGH TEMPS DURING THIS PERIOD LOOK REASONABLE. TUESDAY NIGHT THROUGH THURSDAY...MAJORITY OF THIS PERIOD IS FAIRLY QUIET. NORTHERN STREAM UPPER TROUGH SITUATED OVER THE NORTHERN PLAINS AT 00Z WED IS PROGGED TO SHIFT OVER THE GREAT LAKES ON WED...THEN AMPLIFY WED NIGHT AND THU AS THE SOUTHERN STREAM UPPER LOW PHASES WITH THIS TROUGH. SOME COLDER AIR ADVECTS IN TUE NIGHT AND WED...BUT 850MB TEMPS DO NOT FALL BELOW -10C...SUGGESTING LAKE EFFECT POTENTIAL IS MINIMAL. HOWEVER...SOME UPSLOPE PCPN IS POSSIBLE IN NW FLOW AREAS ON TUE NIGHT...WITH DIURNAL SNOW SHOWER ACTIVITY ON WED UNDER THE UPPER TROUGH. COLDER AIR...PERHAPS WITH 850MB TEMPS FALLING TO -10 TO -12C IS INDICATED TO FLOW IN WED NIGHT AND THU AS THE UPPER TROUGH AMPLIFIES...WHICH COULD GET SOME LAKE EFFECT SNOW GOING. HOWEVER...A RIDGE OF CANADIAN HIGH PRESSURE IS PROGGED TO BUILD IN THU AFTERNOON INTO WESTERN LAKE SUPERIOR...AND THE COMBINATION OF DAYTIME HEATING AND DRY AIR FROM THIS RIDGE SHOULD END ANY LAKE EFFECT OVER THE WEST HALF OF UPPER MI. ALTHOUGH THE AIR IS COLDER THAN TODAY AND TUESDAY...THE AIR IS BETTER FOR MIXING... ESPECIALLY DURING THE DAYTIME. THUS HAVE WENT WITH HIGHS SIMILAR TO TODAY AND TUESDAY...AND THOSE AREAS IN NW DOWNSLOPE LIKE MNM COULD ACTUALLY END UP BEING WARMER. BEYOND THURSDAY...THE ONLY CHANGE MADE TO THE FORECAST WAS TO LOWER LOWS FOR THU NIGHT WITH THE DRY CANADIAN HIGH PRESSURE RIDGE OVERHEAD. THESE LOWS MAY NEED TO BE DROPPED EVEN MORE. DRY FORECAST STILL LOOKS GOOD INTO FRIDAY...AND COULD BE DRIED OUT INTO SATURDAY WITH THE HIGH PRESSURE RIDGE REMAINING IN PLACE PER THE 00Z ECMWF/GFS. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... VFR CONDITIONS WILL CONTINUE UNTIL MID AFTERNOON. CIGS WILL LOWER INTO MVFR CATEGORY BY MID AFTERNOON. BROUGHT IN SNOW BY LATE AFTERNOON IN A PROB30 GROUP WITH THE STEADIER AND HEAVIER SNOW HOLDING OFF UNTIL MID TO LATE EVENING WHEN IFR/LIFR CONDITIONS ARRIVE WITH THE HEAVIER SNOW. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NO GALES SEEN ANYTIME SOON. WENT WITH THE NAM SOLUTION WHICH HAD WEAKER WINDS FOR WED ONWARD AND THEN THE GFS SOLUTION WHICH WAS CLOSE TO THE ECMWF SOLUTION. THE GFS SOLUTION WAS AN OUTLIER WITH ITS STRONGER WINDS AND DID NOT USE. WINDS STAY BELOW 25 KNOTS THE ENTIRE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION/MARINE...GJM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1239 PM CDT TUE MAR 18 2008 .UPDATE...FOR 18Z TAF ISSUANCE && .DISCUSSION... NARROW BAND OF MOD TO HEAVY SNOW MOVING THROUGH S AND E METRO INTO WESTERN WI. LATEST RUC SHOWING AN AXIS OF 700-500MB LAPSE RATES OF AROUND 7.5 DEGREES C JUST SOUTH OF THIS BAND OF SNOW. BACK EDGE OF COMPACT WAVE MOVING UP THROUGH SW MN AS WELL. WILL BEEF UP THE SNOW A LITTLE MORE IN WI THIS MORNING. OTHERWISE MOST OF THE PRECIP SHOULD MOVE OUT OF WI BEFORE NOON. SHOULD BE SOME CLEARING LATER THIS AFTERNOON IN THE WEST BEHIND WAVE IN ND AND CURRENT WAVE MOVING THROUGH EASTERN CWA. STEEP LAPSE RATES SHOWING UP OVER ND AND WESTERN MN LATE THIS AFTERNOON AND EVENING AND YET ANOTHER SMALL WAVE ENTERING WESTERN ND AT THIS TIME COULD CAUSE A AN ISOLD RN OR SNW SHOWER FAR WEST. SOME DIFFERENCES IN MODEL TRENDS FOR NEXT CHANCE OF PRECIP FOR LATE WED AND WED NIGHT. WILL FOLLOW MORE OF THE SREF TRENDS OF CONFINING CHC TO THE SOUTHWEST. BETTER CHANCE OF SNOW FRIDAY...ALTHOUGH THAT WILL LIKELY BE MAINLY OVER SOUTHERN MN. NO BIG TEMP CHANGES WITH READINGS CLOSE TO NORMAL...ALTHOUGH BETTER CHANCE FOR SOME COLDER AIR FILTERING IN BEYOND THE FORECAST PERIOD AFTER SEVERAL OF THESE WNW FLOW SYSTEMS MOVE THROUGH..AND DIG SOMEWHAT TO OUR SOUTHEAST. && .AVIATION.../18Z TAF ISSUANCE/ LINGERING IFR/MVFR CIGS/VSBY BEHIND DEPARTING SYSTEM. CONDS WILL CONTINUE TO IMPROVE AS SUBSIDENCE AND DRYER AIR MOVE IN. MAINLY CLEAR SKIES EXPECTED OVERNIGHT. PATCHY FOG...MAINLY W MN...EXPECTED TO DEVELOP OVERNIGHT. SCT-BKN MID-LEVEL CLOUDS PRECEDING THE NEXT SYSTEM FOR WEDNESDAY MORNING. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JPR/KFM/JVM mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 932 AM CDT TUE MAR 18 2008 .UPDATE... SNOW ADVISORY HAS EXPIRED. VISIBILITY IMPROVING OVER ERN EDGE OF CWA AS SHORTWAVE EVIDENT ON WV IMAGERY/RUC13 50H TEMP FILED MOVES NE OF REGION. BRIEF PATCHY FZDZ OCCURRING ON BACK EDGE OF PRECIP SHIELD OVER WRN CWA EARLY THIS MORNING. WILL NOT INTRODUCE INTO ZONES AS SFC OBS INDICATE VERY SHORT NATURE OF THIS POPTYP. RUC13 SHOWS SOME WARM AIR ADVECTION AT 85H EDGING INTO WRN CWA. WITH SFC/925 WIND ON LIGHT SIDE EXPECT AREAS OF DENSE FOG MAY PERSIST TIL LATE MORNING. FARTHER EAST AREAS OF FOG ALSO OCCURRING AS RELATIVELY WARMER/DRIER AIR ALOFT ADVECTS OVER COOL/MOIST NEAR SFC LAYER. GIVEN CONDITIONS FARTHER WEST OF CWA...SUSPECT THAT FOG MAY LINGER MOST OF DAY...OR AT LEAST SOME LOW CLOUD COVER UNTIL INCREASED MIXING/WINDSHIFT OCCURS COURTESY OF SFC BDRY NOW IN NW CORNER OF STATE. && .PREV DISCUSSION... /ISSUED 353 AM CDT TUE MAR 18 2008/ DISCUSSION...BANDS OF LIGHT SNOW ASSOCIATED WITH A WEAK LOW PRESSURE SYSTEM CONTINUE TO AFFECT THE NORTHLAND EARLY THIS MORNING. LATEST KDLH RADAR IMAGERY SHOWS TWO DISTINCT BANDS...ONE OVER THE TWIN PORTS...WITH A STRONGER ONE OVER THE TWIN CITIES AND WEST CENTRAL WI...WHICH IS TRACKING NE TOWARDS AND OVER NWRN WI. VSBYS ASSOCIATED WITH THESE BANDS GENERALLY RANGE FROM 1 TO 2 MILES...WITH ISOLD REPORTS OF LOWER VSBYS. BECAUSE OF LIGHTER SNOWFALL RATES AND MILD TEMPS...THE SNOW ACCUMULATION HAS BEEN LESS THAN EXPECTED ACROSS THE NORTHLAND. HOWEVER WILL KEEP ADVISORY IN EFFECT THROUGH EARLY THIS MORNING SINCE TRAVEL COULD STILL BE HAZARDOUS. THE SNOW IS PROGGED TO DIMINISH OR MOVE EAST OF OUR FCST AREA BY LATE THIS MORNING OR EARLY THIS AFTERNOON. THERE WILL BE A CONTINUED CHANCE OF SNOW SHOWERS ACROSS OUR NRN ZONES AND SNOWBELT ZONES OF NWRN WI ZONES THROUGH TOMORROW AS SEVERAL WEAK VORTICITY MAXIMA TRACK ACROSS THE UPPER MIDWEST. BUT BECAUSE MOISTURE WILL BE MORE LIMITED...THE CHANCE OF SNOW WILL BE LOW AND SNOWFALL AMOUNTS LIGHT. ELSEWHERE SFC HIGH PRESSURE WILL KEEP CONDITIONS MAINLY DRY. AVIATION...WIDESPREAD LIFR/IFR CIGS/VSBYS WILL PREVAIL EARLY THIS MORNING DUE TO FOG AND LIGHT SNOW. DRIER AIR MOVING IN FROM THE WEST BEHIND A DEPARTING LOW PRESSURE SYSTEM...WILL BRING SOME IMPROVEMENT IN CONDITIONS AS THE DAY WEARS ON. CIGS SHOULD RISE TO MVFR DURING THE AFTERNOON...WITH SOME VFR CONDITIONS EXPECTED BY THIS EVENING. THERE IS THE POTENTIAL FOR MORE FOG AND LOW CLOUDS TO REDEVELOP LATER TONIGHT...RESULTING IN LOCALIZED IFR/LIFR CIGS/VSBYS ONCE AGAIN. && POINT TEMPS/POPS... DLH 35 22 35 13 / 40 10 10 10 INL 37 20 34 9 / 30 20 20 10 BRD 37 22 38 15 / 10 10 10 10 HYR 37 20 38 13 / 70 10 10 10 ASX 35 24 36 16 / 80 20 20 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ CANNON mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 636 AM CDT TUE MAR 18 2008 .UPDATE...FOR 12Z AVIATION DISCUSSION BELOW && .DISCUSSION.../ISSUED 357 AM CDT TUE MAR 18 2008/ NARROW BAND OF MOD TO HEAVY SNOW MOVING THROUGH S AND E METRO INTO WESTERN WI. LATEST RUC SHOWING AN AXIS OF 700-500MB LAPSE RATES OF AROUND 7.5 DEGREES C JUST SOUTH OF THIS BAND OF SNOW. BACK EDGE OF COMPACT WAVE MOVING UP THROUGH SW MN AS WELL. WILL BEEF UP THE SNOW A LITTLE MORE IN WI THIS MORNING. OTHERWISE MOST OF THE PRECIP SHOULD MOVE OUT OF WI BEFORE NOON. SHOULD BE SOME CLEARING LATER THIS AFTERNOON IN THE WEST BEHIND WAVE IN ND AND CURRENT WAVE MOVING THROUGH EASTERN CWA. STEEP LAPSE RATES SHOWING UP OVER ND AND WESTERN MN LATE THIS AFTERNOON AND EVENING AND YET ANOTHER SMALL WAVE ENTERING WESTERN ND AT THIS TIME COULD CAUSE A AN ISOLD RN OR SNW SHOWER FAR WEST. SOME DIFFERENCES IN MODEL TRENDS FOR NEXT CHANCE OF PRECIP FOR LATE WED AND WED NIGHT. WILL FOLLOW MORE OF THE SREF TRENDS OF CONFINING CHC TO THE SOUTHWEST. BETTER CHANCE OF SNOW FRIDAY...ALTHOUGH THAT WILL LIKELY BE MAINLY OVER SOUTHERN MN. NO BIG TEMP CHANGES WITH READINGS CLOSE TO NORMAL...ALTHOUGH BETTER CHANCE FOR SOME COLDER AIR FILTERING IN BEYOND THE FORECAST PERIOD AFTER SEVERAL OF THESE WNW FLOW SYSTEMS MOVE THROUGH..AND DIG SOMEWHAT TO OUR SOUTHEAST. && .AVIATION.../12Z TAF ISSUANCE/ SNOW ACROSS EAST CENTRAL MN AND WEST CENTRAL WI AT THE START OF THE TAF PERIOD WILL COME TO AN END AROUND 14Z AT KMSP...AND BETWEEN 15Z AND 16Z AT KRNH AND KEAU. ATTENDANT IFR CEILINGS/VISIBILITIES WILL IMPROVE SHORTLY THEREAFTER...BUT MVFR CEILINGS WILL PERSIST THROUGH THE MORNING. AREAS OF FOG WILL RESTRICT VISIBILITIES TO IFR/LIFR THIS MORNING AT KSTC/KAXN/KRWF...WITH IMPROVEMENT EXPECTED DURING THE LATE MORNING. CONDITIONS WILL IMPROVE TO THE VFR CATEGORY THIS AFTERNOON AS THE TROUGH PUSHES OFF TO THE EAST...WITH LIGHT WEST- NORTHWEST WINDS EXPECTED TONIGHT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 357 AM CDT TUE MAR 18 2008 .DISCUSSION... NARROW BAND OF MOD TO HEAVY SNOW MOVING THROUGH S AND E METRO INTO WESTERN WI. LATEST RUC SHOWING AN AXIS OF 700-500MB LAPSE RATES OF AROUND 7.5 DEGREES C JUST SOUTH OF THIS BAND OF SNOW. BACK EDGE OF COMPACT WAVE MOVING UP THROUGH SW MN AS WELL. WILL BEEF UP THE SNOW A LITTLE MORE IN WI THIS MORNING. OTHERWISE MOST OF THE PRECIP SHOULD MOVE OUT OF WI BEFORE NOON. SHOULD BE SOME CLEARING LATER THIS AFTERNOON IN THE WEST BEHIND WAVE IN ND AND CURRENT WAVE MOVING THROUGH EASTERN CWA. STEEP LAPSE RATES SHOWING UP OVER ND AND WESTERN MN LATE THIS AFTERNOON AND EVENING AND YET ANOTHER SMALL WAVE ENTERING WESTERN ND AT THIS TIME COULD CAUSE A AN ISOLD RN OR SNW SHOWER FAR WEST. SOME DIFFERENCES IN MODEL TRENDS FOR NEXT CHANCE OF PRECIP FOR LATE WED AND WED NIGHT. WILL FOLLOW MORE OF THE SREF TRENDS OF CONFINING CHC TO THE SOUTHWEST. BETTER CHANCE OF SNOW FRIDAY...ALTHOUGH THAT WILL LIKELY BE MAINLY OVER SOUTHERN MN. NO BIG TEMP CHANGES WITH READINGS CLOSE TO NORMAL...ALTHOUGH BETTER CHANCE FOR SOME COLDER AIR FILTERING IN BEYOND THE FORECAST PERIOD AFTER SEVERAL OF THESE WNW FLOW SYSTEMS MOVE THROUGH..AND DIG SOMEWHAT TO OUR SOUTHEAST. && .AVIATION.../06Z TAF ISSUANCE/ WIDESPREAD IFR CEILINGS AND VISIBILITIES WILL PERSIST AT TAF SITES OVERNIGHT...TO THE NORTH OF A TROUGH OF LOW PRESSURE MOVING ACROSS THE CENTRAL MS VALLEY REGION. PERIODS OF LIGHT TO MODERATE SNOW WILL OCCUR OVERNIGHT AS WELL...WITH THE EXCEPTION OF KAXN WHERE THE MAIN VISIBILITY RESTRICTION WILL BE BR/FOG. CIRA IR SATELLITE INDICATES THAT SOUTH/EAST CENTRAL MN AND WEST CENTRAL WISCONSIN MAY BE LACKING ICE CRYSTALS...SO -RASN OR -DZ WILL BE POSSIBLE OVERNIGHT AT KMSP/KRNH/KEAU. BY DAYBREAK TUESDAY...THE BACK EDGE OF THE SNOW AREA SHOULD BE NEAR KMSP...WITH PRECIP EXPECTED TO LINGER AT KEAU/KRNH UNTIL AROUND 15Z. EXPECT VISIBILITIES TO IMPROVE TO THE VFR CATEGORY AFTER DAYBREAK...ALTHOUGH IFR TO LOW- END MVFR CIGS WILL LINGER THROUGH THE MORNING. IMPROVING CONDITIONS AND ATTENDANT VFR CONDITIONS ARE EXPECTED DURING THE AFTERNOON...ALONG WITH LIGHT WEST TO NORTHWEST WINDS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JPR/LS/JVM mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DULUTH MN 852 PM CDT MON MAR 17 2008 .UPDATE...CURRENT HEADLINES AND SNOW AMOUNTS ARE IN GREAT SHAPE AS UPPER LEVEL JET AXIS SHIFTS SLOWLY SOUTHEASTWARD. THE UPPER JET IS ALIGNED PARALLEL TO THE UPPER LEVEL TROF. EMBEDDED PIECES OF ENERGY ARE ADVECTING NORTHEASTWARD THROUGH THE AREA AND IS EVIDENCED BY A NEW BATCH OF MODERATE SNOW BREAKING OUT OVER THE SOUTHERN TIER OF THE FA ATTM. MADE SOME MINOR ADJUSTMENTS TO THE REST OF THE FORECAST INCLUDING RAISING MIN TEMPS A BIT. && .PREV DISCUSSION... /ISSUED 308 PM CDT MON MAR 17 2008/ DISCUSSION... SPLIT FLOW IN WESTERLIES WITH CWA UNDERNEATH THE INFLUENCE OF NRN BRANCH AND ITS APPROACHING MID LVL TROF. SRN BRANCH VORTEX WILL REMAIN WELL SOUTH OF REGION WITH MAJORITY OF SIGNIFICANT PW AND LIFT. DIFFICULT FORECAST THIS AFTERNOON AS SIGNALS FOR LIFT HAVE BEEN RATHER TRANSIENT IN NATURE AND MDL CONSENSUS HAS BEEN LACKING. THE LATEST RUC13 ANIMATION DEPICTS WELL DEFINED RRQ OF 30H JET LIFTING NORTHEAST OF REGION. THIS HAS HELP INDUCE A LLJ ACROSS ERN MN THIS AFTERNOON. 12Z NAM HAS LLJ AXIS IN GOOD AGREEMENT WITH CURRENT LOCATION. AREA OF DECENT ISENTROPIC LIFT ASSOCIATED WITH THIS FEATURE LIFTING NORTH AS WELL. EXPECT BEST ORIENTATION OF LLJ/ISENTROPIC LIFT TO FOCUS ACROSS SE CWA THIS EVENING BEFORE OVERALL FORCING BECOMES QUITE WEAK ACROSS MOST OF CWA. ALTHOUGH POPS WILL REMAIN HIGH...ONCE AGAIN... QPF WITH THIS SYSTEM SHOULD REMAIN LOW. AS A RESULT... HAVE RESHAPED AREA OF HEADLINES OVERNIGHT AND MOVED START TIME CLOSER TO ZONE ISSUANCE. WILL CHANGE WWA TO SNOW ADV AS POP/TYPE ISSUES NOT EXPECTED TO BE SIGNIFICANT. EXPECT MORE OF A TWO TO 4 INCH SNOWFALL IN MOST LOCATIONS WITH ISOLATED 5 INCH POSSIBLE IN SE CWA. MOST SYNOPTIC SCALE FORCING SHOULD BE EXITING REGION BY EARLY TUESDAY. EXTENDED...WED THROUGH FRIDAY...QUIET PATTERN AS NRN BRANCH DOMINATES REGION WITH ONLY WEAK SHORTWAVES MIGRATING THROUGH. ALTHOUGH LOW LVL WINDS MAY FAVOR LES POTENTIAL WEDNESDAY OVER WI SNOWBELT...IT LOOKS LIKE DEEP LAYER DRYING WITH INVERSION WOULD LIMIT ABILITY OF ANY MESOSCALE LIFT TO GENERATE ADEQUATE DEPTH OF CLOUD DEVELOPMENT. AVIATION... MVFR AND IFR CEILINGS WILL CONTINUE THROUGH THE PERIOD AS A WEAK TROUGH OF LOW PRESSURE MOVES THROUGH THE REGION. IFR OR LOW MVFR VSBYS IN LIGHT SNOW OR FOG WILL ALSO PERSIST THROUGH THE EVENING. && POINT TEMPS/POPS... DLH 26 34 23 35 / 90 70 10 10 INL 28 34 20 34 / 60 40 10 10 BRD 29 37 21 38 / 90 40 10 10 HYR 30 35 22 38 / 100 80 10 10 ASX 29 34 24 36 / 100 80 10 30 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...SNOW ADVISORY UNTIL 7 AM CDT TUESDAY FOR CARLTON/SOUTHERN ST. LOUIS-PINE. WI...SNOW ADVISORY UNTIL 7 AM CDT TUESDAY FOR ASHLAND-BAYFIELD- BURNETT-DOUGLAS-IRON-PRICE-SAWYER-WASHBURN. $$ GSF mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 308 PM CDT MON MAR 17 2008 .DISCUSSION... SPLIT FLOW IN WESTERLIES WITH CWA UNDERNEATH THE INFLUENCE OF NRN BRANCH AND ITS APPROACHING MID LVL TROF. SRN BRANCH VORTEX WILL REMAIN WELL SOUTH OF REGION WITH MAJORITY OF SIGNIFICANT PW AND LIFT. DIFFICULT FORECAST THIS AFTERNOON AS SIGNALS FOR LIFT HAVE BEEN RATHER TRANSIENT IN NATURE AND MDL CONSENSUS HAS BEEN LACKING. THE LATEST RUC13 ANIMATION DEPICTS WELL DEFINED RRQ OF 30H JET LIFTING NORTHEAST OF REGION. THIS HAS HELP INDUCE A LLJ ACROSS ERN MN THIS AFTERNOON. 12Z NAM HAS LLJ AXIS IN GOOD AGREEMENT WITH CURRENT LOCATION. AREA OF DECENT ISENTROPIC LIFT ASSOCIATED WITH THIS FEATURE LIFTING NORTH AS WELL. EXPECT BEST ORIENTATION OF LLJ/ISENTROPIC LIFT TO FOCUS ACROSS SE CWA THIS EVENING BEFORE OVERALL FORCING BECOMES QUITE WEAK ACROSS MOST OF CWA. ALTHOUGH POPS WILL REMAIN HIGH...ONCE AGAIN... QPF WITH THIS SYSTEM SHOULD REMAIN LOW. AS A RESULT... HAVE RESHAPED AREA OF HEADLINES OVERNIGHT AND MOVED START TIME CLOSER TO ZONE ISSUANCE. WILL CHANGE WWA TO SNOW ADV AS POPTYP ISSUES NOT EXPECTED TO BE SIGNIFICANT. EXPECT MORE OF A TWO TO 4 INCH SNOWFALL IN MOST LOCATIONS WITH ISOLATED 5 INCH POSSIBLE IN SE CWA. MOST SYNOPTIC SCALE FORCING SHOULD BE EXITING REGION BY EARLY TUESDAY. EXTENDED...WED THROUGH FRIDAY...QUIET PATTERN AS NRN BRANCH DOMINATES REGION WITH ONLY WEAK SHORTWAVES MIGRATING THROUGH. ALTHOUGH LOW LVL WINDS MAY FAVOR LES POTENTIAL WEDNESDAY OVER WI SNOWBELT...IT LOOKS LIKE DEEP LAYER DRYING WITH INVERSION WOULD LIMIT ABILITY OF ANY MESOSCALE LIFT TO GENERATE ADEQUATE DEPTH OF CLOUD DEVELOPMENT. && .AVIATION... MVFR AND IFR CEILINGS WILL CONTINUE THROUGH THE PERIOD AS A WEAK TROUGH OF LOW PRESSURE MOVES THROUGH THE REGION. IFR OR LOW MVFR VSBYS IN LIGHT SNOW OR FOG WILL ALSO PERSIST THROUGH THE EVENING. && POINT TEMPS/POPS... DLH 26 34 23 35 / 90 70 10 10 INL 25 34 20 34 / 50 40 10 10 BRD 26 37 21 38 / 90 40 10 10 HYR 25 35 22 38 / 100 80 10 10 ASX 27 34 24 36 / 100 80 10 30 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...SNOW ADVISORY UNTIL 7 AM CDT TUESDAY FOR CARLTON/SOUTHERN ST. LOUIS-PINE. WI...SNOW ADVISORY UNTIL 7 AM CDT TUESDAY FOR ASHLAND-BAYFIELD- BURNETT-DOUGLAS-IRON-PRICE-SAWYER-WASHBURN. $$ CANNON/MELDE mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 944 AM CDT MON MAR 17 2008 .DISCUSSION... SNOW IS SPREADING NORTHEAST FROM SWRN CWA INTO TWIN PORTS. HAVE INCREASED POPS FROM PREVIOUS ZONES/GRIDS. LATEST RUC13 AND NAM12 HAVE DECENT HANDLE ON AREAL COVERAGE OF PRECIP SHIELD AND WILL USE THROUGH TODAY. HAVE ALSO KEPT POPTYP AS ALL SNOW AS LATEST NAM SNDGS KEEP IC DESCENDING INTO SUFFICIENTLY COLD BL...ESPECIALLY WITH SOME EVAP COOLING POTENTIAL. AMNTS SHOULD BE LIGHT AS ISENTROPIC ASCENT STILL ENCOUNTERS ANTICYCLONIC CURVATURE IN LOW LEVELS. STILL ANTICIPATE MAIN SHOT OF SNOW TONIGHT WITH DEEPER LAYER OF FORCING WITH 85/50H OMEGA FIELDS. WILL AWAIT 12Z GFS TO SEE IF ANY SIGNIFICANT CHANGES ARE ANTICIPATED. && POINT TEMPS/POPS... DLH 33 26 34 22 / 70 90 70 20 INL 37 25 37 19 / 40 50 40 20 BRD 36 26 37 21 / 80 80 50 10 HYR 35 25 35 22 / 70 100 80 20 ASX 34 27 34 24 / 50 100 90 30 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 9 AM CDT TUESDAY FOR CARLTON/SOUTHERN ST. LOUIS-CENTRAL ST. LOUIS- PINE. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 12 PM CDT TUESDAY FOR NORTHERN COOK/NORTHERN LAKE-SOUTHERN COOK/LAKESHORE-SOUTHERN LAKE/LAKESHORE. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CDT TUESDAY FOR CROW WING-NORTHERN AITKIN-SOUTHERN AITKIN. WI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 9 AM CDT TUESDAY FOR BURNETT. WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 12 PM CDT TUESDAY FOR ASHLAND-BAYFIELD-DOUGLAS-IRON-PRICE-SAWYER- WASHBURN. $$ CANNON mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 1023 PM CDT TUE MAR 18 2008 .DISCUSSION...THE SURFACE LOW IS NOW CENTERED OVER THE ARKLATEX REGION THIS EVENING. THE LINE OF STORMS IS NOW DEVELOPING OVER EAST TEXAS. OVER THE CWFA WE ARE SEEING SHOWERS DEVELOP...WHICH SHOULD CONTINUE UNTIL THE LINE OF STORMS REACHES THE AREA. OVERALL THINKING HAS NOT CHANGED OVER THE PAST COUPLE OF HOURS. HAVE NOT CHANGED POP AND WEATHER GRIDS AS A RESULT. DID MAKE A COUPLE OF QUICK UPDATES MAINLY FOR TEMPERATURES. TEMPERATURES ARE HOLDING NEARLY STEADY AROUND THE LOWER 70S EAST TO UPPER 70S WEST THIS EVENING. THEY ARE DEFINITELY FALLING MUCH SLOWER THAN EXPECTED WITH ALL OF THE CLOUD COVER AND STRONG SOUTHERLY WINDS AROUND. AS A RESULT HAVE ADJUSTED THE LOWER TEMPERATURES UP A DEGREE OR TWO...MAINLY OVER THE EAST WHICH WILL BE THE LAST TO SEE THE LINE OF STORMS MOVE THROUGH. ALSO ADJUSTED HOURLY TEMPS BASED ON THIS CHANGE AND OBSERVATIONAL TRENDS. OTHERWISE THE FORECAST LOOKS ON TRACK AND WILL ATTACH THE PREVIOUS DISCUSSION. && .PREVIOUS DISCUSSION...THINGS ARE EVOLVING SLOWLY AT THIS POINT...BUT ARE EXPECTED TO HAVE A MARKED INCREASE IN THE ACTION BETWEEN 8-9 PM TO OUR WEST WITH THINGS EVOLVING QUICKLY THROUGH THE REMAINDER OF THE EVENING AND ACCELERATING EASTWARD ACROSS MY FORECAST AREA BETWEEN MIDNIGHT AND 7 AM. DUE TO THE SLOW EVOLUTION UP TO THIS POINT...THE FORECAST HAS BEEN ADJUSTED TO REFLECT THAT TIMING. AS FOR THE CONDITIONS OUTSIDE...WINDS WILL REMAIN QUITE STRONG AHEAD OF THE SQUALL LINE AS THE SFC LOW EDGES EVER CLOSER. ALOFT...WINDS WILL STEADILY INCREASE IN ADVANCE OF THE SYSTEM...CREATING A STRONGLY SHEARED ENVIRONMENT WITH 0-1 KM VALUES BETWEEN 45-50KTS. LOW LEVEL HELICITIES...0-1KM...WILL ALSO BE OFF THE CHART WITH VALUES BETWEEN 400-600 M2/S2. STRONG ASCENT WILL APPROACH THE FORECAST AREA BY 10-11PM AND HELP TO REMOVE THE WARM MID LEVEL LAYER. THE RESULT WILL BE A STRONGLY FORCED SQUALL LINE MOVING ACROSS THE AREA. AS THIS LINE EVOLVES...BOWING SEGMENTS WILL BE COMMON AND POSE A SIG WIND THREAT. SOME GUSTS IN THE SEGMENTS COULD EXCEED 80 MPH. ALSO...DUE TO THE VERY HIGH LEVELS OF LOW LEVEL WIND SHEAR...THESE BOWING SEGMENTS WILL POSE A DECENT TORNADO RISK. OFTEN TIMES...THESE BOWING SEGMENTS IN SIMILAR VERY HIGH SHEAR ENVIRONMENTS ARE VERY EFFICIENT AT PRODUCING TORNADOES. AS HAS BEEN THE CASE WITH ALL PREV FORECAST FOR THIS EVENT...INSTABILITY WILL REMAIN ON THE LOW SIDE. HOWEVER...GRIDDED MLCAPE VALUES FROM THE RUC OFFER 400-600 J/KG JUST AHEAD OF THE LINE AND GFS BUFR SOUNDINGS SHOW 600-1000 J/KG OF MLCAPE. THIS HAS BEEN VERY CONSISTENT AND MATCHES WELL WITH THE OBSERVED 00Z RAOBS AT SHV/LCH. IF THAT TYPE OF INSTABILITY CAN REMAIN AS THE STRONG FORCING ASSOCIATED WITH +90KTS AT 500MB AND 70-80KTS AT 700MB...THEN A NASTY LINE WITH BOWING SEGMENTS CAN BE EXPECTED. LATEST GRAPHICAST OUTLINES THE TIMING WITH AREAS ALONG AND W OF THE MS RIVER SEEING ACTIVITY BETWEEN 10 PM AND 1 AM. THE I-55 CORRIDOR BETWEEN 1-4 AM WHILE THE E 1/3 BETWEEN 4-7 AM. && .AVIATION...VFR TO MVFR FLIGHT CATEGORIES WILL CONTINUE THROUGH THE NEXT COUPLE OF HOURS. CEILINGS HAVE BEGUN TO LOWER FROM WEST TO EAST THIS EVENING AND WILL CONTINUE TO DO SO...BRINGING FLIGHT CATEGORIES TO MVFR. SHOWERS WITH A FEW POSSIBLE RUMBLES OF THUNDER CAN BE EXPECTED OVER THE REGION AHEAD OF AN APPROACHING SQUALL LINE. THE SQUALL LINE IS EXPECTED TO MOVE THROUGH THE REGION MAINLY OVERNIGHT...REACHING THE MISSISSIPPI RIVER BETWEEN 06Z-09Z AND LEAVING THE EASTERN SITES BETWEEN 10Z-13Z. THE MAIN CONCERN WITH THIS SQUALL LINE WILL BE DAMAGING STRAIGHT LINE WINDS. VISIBILITIES WILL ALSO DROP TO IFR OR LIFR AS THIS LINE MOVES THROUGH. AFTER THE SQUALL LINE MOVES THROUGH THE AREA...MVFR CEILINGS SHOULD PERSIST THROUGH THE REMAINDER OF THE FORECAST PERIOD. IN ADDITION TO THE SEVERE WEATHER POTENTIAL...THE AREA WILL CONTINUE TO SEE STRONG WINDS BEFORE THE SQUALL LINE EVEN REACHES THE AREA. SUSTAINED WINDS BETWEEN 15-25KTS WITH GUSTS OF AROUND 30-35KTS CAN BE EXPECTED OVER THE ENTIRE REGION. SITES ALONG AND WEST OF THE INTERSTATE 55 CORRIDOR WILL SEE EVEN HIGHER WINDS THIS EVENING...WITH SUSTAINED AROUND 20-30KTS WITH GUSTS OF 30-40KTS. THIS WILL BE AHEAD OF THE SQUALL LINE AND IN ADDITION TO THE STRONG WINDS THAT WILL BE PROVIDED WITH THE SQUALL LINE. AFTER THE LINE MOVES THROUGH...WINDS WILL SUBSIDE A LITTLE...BUT SHOULD STILL BE SUSTAINED AT AROUND 15-20KTS WITH GUSTS OF 20-25KTS THROUGH THE REMAINDER OF THE FORECAST PACKAGE. /14/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 58 63 41 70 / 100 12 0 0 MERIDIAN 61 67 39 69 / 100 37 0 0 VICKSBURG 56 63 42 69 / 100 10 0 0 HATTIESBURG 61 69 41 73 / 100 31 0 0 NATCHEZ 56 64 40 67 / 100 3 0 0 GREENVILLE 55 59 42 69 / 100 28 0 0 GREENWOOD 57 61 39 68 / 100 27 0 0 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...LAKE WIND ADVISORY UNTIL 7 AM CDT WEDNESDAY FOR MSZ030-031-033- 038-039-045-046-051-052-056>058-064>066-072>074. LAKE WIND ADVISORY UNTIL 7 AM CDT WEDNESDAY FOR MSZ018-019- 025>029-032-034>037-040>044-047>050-053>055-059>063. WIND ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR MSZ018-019-025>029- 032-034>037-040>044-047>050-053>055-059>063. LA...LAKE WIND ADVISORY UNTIL 7 AM CDT WEDNESDAY FOR LAZ007>009-015- 016-023>026. WIND ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR LAZ007>009-015-016- 023>026. AR...LAKE WIND ADVISORY UNTIL 7 AM CDT WEDNESDAY FOR ARZ074-075. WIND ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR ARZ074-075. && $$ 14 ms AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 810 PM CDT TUE MAR 18 2008 .DISCUSSION...THINGS ARE EVOLVING SLOWLY AT THIS POINT...BUT ARE EXPECTED TO HAVE A MARKED INCREASE IN THE ACTION BETWEEN 8-9 PM TO OUR WEST WITH THINGS EVOLVING QUICKLY THROUGH THE REMAINDER OF THE EVENING AND ACCELERATING EASTWARD ACROSS MY FORECAST AREA BETWEEN MIDNIGHT AND 7 AM. DUE TO THE SLOW EVOLUTION UP TO THIS POINT...THE FORECAST HAS BEEN ADJUSTED TO REFLECT THAT TIMING. AS FOR THE CONDITIONS OUTSIDE...WINDS WILL REMAIN QUITE STRONG AHEAD OF THE SQUALL LINE AS THE SFC LOW EDGES EVER CLOSER. ALOFT...WINDS WILL STEADILY INCREASE IN ADVANCE OF THE SYSTEM...CREATING A STRONGLY SHEARED ENVIRONMENT WITH 0-1 KM VALUES BETWEEN 45-50KTS. LOW LEVEL HELICITIES...0-1KM...WILL ALSO BE OFF THE CHART WITH VALUES BETWEEN 400-600 M2/S2. STRONG ASCENT WILL APPROACH THE FORECAST AREA BY 10-11PM AND HELP TO REMOVE THE WARM MID LEVEL LAYER. THE RESULT WILL BE A STRONGLY FORCED SQUALL LINE MOVING ACROSS THE AREA. AS THIS LINE EVOLVES...BOWING SEGMENTS WILL BE COMMON AND POSE A SIG WIND THREAT. SOME GUSTS IN THE SEGMENTS COULD EXCEED 80 MPH. ALSO...DUE TO THE VERY HIGH LEVELS OF LOW LEVEL WIND SHEAR...THESE BOWING SEGMENTS WILL POSE A DECENT TORNADO RISK. OFTEN TIMES...THESE BOWING SEGMENTS IN SIMILAR VERY HIGH SHEAR ENVIRONMENTS ARE VERY EFFICIENT AT PRODUCING TORNADOES. AS HAS BEEN THE CASE WITH ALL PREV FORECAST FOR THIS EVENT...INSTABILITY WILL REMAIN ON THE LOW SIDE. HOWEVER...GRIDDED MLCAPE VALUES FROM THE RUC OFFER 400-600 J/KG JUST AHEAD OF THE LINE AND GFS BUFR SOUNDINGS SHOW 600-1000 J/KG OF MLCAPE. THIS HAS BEEN VERY CONSISTENT AND MATCHES WELL WITH THE OBSERVED 00Z RAOBS AT SHV/LCH. IF THAT TYPE OF INSTABILITY CAN REMAIN AS THE STRONG FORCING ASSOCIATED WITH +90KTS AT 500MB AND 70-80KTS AT 700MB...THEN A NASTY LINE WITH BOWING SEGMENTS CAN BE EXPECTED. LATEST GRAPHICAST OUTLINES THE TIMING WITH AREAS ALONG AND W OF THE MS RIVER SEEING ACTIVITY BETWEEN 10 PM AND 1 AM. THE I-55 CORRIDOR BETWEEN 1-4 AM WHILE THE E 1/3 BETWEEN 4-7 AM. && .AVIATION...VFR TO MVFR FLIGHT CATEGORIES WILL CONTINUE THROUGH THE REMAINDER OF THE AFTERNOON THROUGH THE MID EVENING. BY THE MID TO LATE EVENING AND OVERNIGHT HOURS...CEILINGS WILL BEGIN TO LOWER FROM WEST TO EAST...BRINGING FLIGHT CATEGORIES TO MVFR. SHOWERS WITH A FEW POSSIBLE RUMBLES OF THUNDER CAN BE EXPECTED OVER THE REGION AHEAD OF AN APPROACHING SQUALL LINE. THE SQUALL LINE IS EXPECTED TO MOVE THROUGH THE REGION MAINLY OVERNIGHT...REACHING THE MISSISSIPPI RIVER BETWEEN 04Z-07Z AND LEAVING THE EASTERN SITES BETWEEN 10Z-13Z. THE MAIN CONCERN WITH THIS SQUALL LINE WILL BE DAMAGING STRAIGHT LINE WINDS. VISIBILITIES WILL ALSO DROP TO IFR OR LIFR AS THIS LINE MOVES THROUGH. AFTER THE SQUALL LINE MOVES THROUGH THE AREA...MVFR CEILINGS SHOULD PERSIST THROUGH THE REMAINDER OF THE FORECAST PERIOD. IN ADDITION TO THE SEVERE WEATHER POTENTIAL...THE AREA WILL CONTINUE TO SEE STRONG WINDS BEFORE THE SQUALL LINE EVEN REACHES THE AREA. SUSTAINED WINDS BETWEEN 15-25KTS WITH GUSTS OF AROUND 30-35KTS CAN BE EXPECTED OVER THE ENTIRE REGION. SITES ALONG AND WEST OF THE INTERSTATE 55 CORRIDOR WILL SEE EVEN HIGHER WINDS THIS EVENING...WITH SUSTAINED AROUND 20-30KTS WITH GUSTS OF 30-40KTS. THIS WILL BE AHEAD OF THE SQUALL LINE AND IN ADDITION TO THE STRONG WINDS THAT WILL BE PROVIDED WITH THE SQUALL LINE. AFTER THE LINE MOVES THROUGH...WINDS WILL SUBSIDE A LITTLE...BUT SHOULD STILL BE SUSTAINED AT AROUND 15-20KTS WITH GUSTS OF 20-25KTS THROUGH THE REMAINDER OF THE FORECAST PACKAGE. /14/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 56 63 41 70 / 100 12 0 0 MERIDIAN 58 67 39 69 / 100 37 0 0 VICKSBURG 55 63 42 69 / 100 10 0 0 HATTIESBURG 58 69 41 73 / 100 31 0 0 NATCHEZ 55 64 40 67 / 100 3 0 0 GREENVILLE 54 59 42 69 / 100 28 0 0 GREENWOOD 56 61 39 68 / 100 27 0 0 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...LAKE WIND ADVISORY UNTIL 7 AM CDT WEDNESDAY FOR MSZ030-031-033- 038-039-045-046-051-052-056>058-064>066-072>074. LAKE WIND ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT WEDNESDAY FOR MSZ018-019-025>029-032-034>037-040>044-047>050-053>055- 059>063. WIND ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR MSZ018-019-025>029- 032-034>037-040>044-047>050-053>055-059>063. LA...LAKE WIND ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT WEDNESDAY FOR LAZ007>009-015-016-023>026. WIND ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR LAZ007>009-015-016- 023>026. AR...LAKE WIND ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT WEDNESDAY FOR ARZ074-075. WIND ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR ARZ074-075. && $$ CME 14 ms AREA FORECAST DISCUSSION...UPDATED FOR AVIATION NATIONAL WEATHER SERVICE JACKSON MS 645 AM CDT TUE MAR 18 2008 .SHORT TERM...TODAY THROUGH WEDNESDAY...ALTHOUGH MODELS ARE A LITTLE SLOWER THIS RUN WITH THE PROGRESSION OF THE STRONG LOW PRESSURE SYSTEM TO AFFECT OUR CWFA TONIGHT...ANOTHER NIGHT-TIME SEVERE WEATHER EVENT IS STILL EXPECTED. WATER VAPOR IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND A CUTOFF LOW SPINNING OVER MEXICO SW OF THE TEXAS BIG BEND. BELIEVE THIS IS A LITTLE FARTHER SOUTH THAN THE MODELS PROGGED A DAY OR TWO AGO AND MAY ACCOUNT FOR THE SLOWER PROGRESSION CURRENTLY FCST. SURFACE ANALYSIS HAS A 1000MB LOW OVER SOUTHWEST TEXAS WITH HIGH PRESSURE ALONG THE EASTERN SEABOARD. THE TIGHT PRESSURE GRADIENT BETWEEN THE TWO ARE RESULTING IN BREEZY CONDITIONS OVER THE AREA ALREADY...WITH STRONGER WINDS EXPECTED LATER TODAY. HAVE CONTINUED INHERITED WIND AND LAKE WIND ADVISORIES THROUGH TONIGHT. BOTH THE SURFACE LOW AND CUTOFF LOW ARE EXPECTED TO MOVE TO THE NORTHEAST ACROSS TEXAS TODAY AND STRENGTHEN. MODELS ARE IN FAIR AGREEMENT THAT THE SFC LOW WILL BE ENTERING SW ARKANSAS BY 00Z AND OVER CENTRAL TENNESSEE BY WEDNESDAY MORNING. THE TRAILING COLD FRONT WILL NOT MOVE ACROSS OUR AREA UNTIL WEDNESDAY BUT...A SQUALL LINE IS EXPECTED TO DEVELOP ALONG THE FRONT OVER EAST TEXAS TODAY AND MOVE AHEAD ACROSS OUR AREA TONIGHT. THERE MAY BE A COUPLE OF STRONG TO SEVERE STORMS IN OUR WESTERN COUNTIES AND PARISHES LATE THIS AFTERNOON BUT THE MAIN FOCUS FOR SEVERE STORMS WILL BE WITH THE EXPECTED SQUALL LINE TONIGHT. THE ENVIRONMENT OVER OUR REGION TODAY AHEAD OF THE SQUALL LINE WILL BE WARM AND MOIST WITH INCREASING WIND SHEAR. DEW POINTS HAVE RISEN BACK INTO THE LOWER 60S ACROSS THE SOUTHWEST HALF OF THE AREA THIS MORNING AND WILL INCREASE TODAY. STRONG GRADIENT WINDS WITH GUSTS OVER 35MPH TODAY AHEAD OF THE SQUALL LINE MAY RESULT IN DOWNED TREES...BUT EXPECT A SQUALL LINE PUSHING EAST AT 40-50MPH WITH BOWING SEGMENTS PRODUCING DAMAGING AND PERHAPS A FEW TORNADOES. ALTHOUGH THE SQUALL LINE WILL BE SHIFTING EAST OF OUR AREA WEDNESDAY MORNING...THE COLD FRONT WILL FOLLOW LATER IN THE DAY. LOW CLOUDS BUILDING BACK IN ALONG AND BEHIND THIS COLD FRONTAL PASSAGE WILL HAVE A HARD TIME CLEARING BEFORE WEDNESDAY EVENING. TEMPERATURES WILL HAVE A STRUGGLE MOVING UPWARD THROUGH THE 60S. /22/ .LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY...THE UPPER TROUGH AXIS WILL BE PULLING WELL AWAY FROM THE ARKLAMISS REGION ON WEDNESDAY NIGHT...ALTHOUGH LOW CLOUDS ASSOCIATED WITH THE LOW LEVEL THERMAL TROUGH IN THE WAKE OF THE COLD FRONT WILL TAKE LONGER TO CLEAR OUT TO THE EAST. EXPECT NORTHWEST WINDS TO REMAIN A LITTLE GUSTY IN MOST AREAS IN THE EVENING...BUT WILL SLACKEN FROM WEST TO EAST AS THE NIGHT WEARS ON. DRIER AND COOLER AIR FILTERING INTO THE LOWER MS VALLEY WILL ALLOW TEMPS TO DROP RATHER CONSIDERABLY BY MORNING...ESPECIALLY OVER WESTERN ZONES WHERE A LONGER PERIOD OF LIGHT WINDS BEFORE SUNRISE WILL PROVIDE BETTER RAD COOLING CONDITIONS. CUT MINS 1 TO 2 DEGREES BELOW 00Z MEX IN THOSE AREAS..BUT WENT WITH GUIDANCE ELSEWHERE. EXPECT A RANGE OF UPPER 30S WEST TO LOWER 40S EAST. THURSDAY LOOKS TO BE A BEAUTIFUL DAY WITH HIGH PRESSURE BRINGING SUNNY SKIES...LIGHT WINDS...AND TEMPERATURES JUST A TOUCH BELOW NORMAL FOR THE SEASON. EXPECT HIGHS MAINLY IN THE UPPER 60S AND I WENT RIGHT WITH 00Z MEX FOR TEMPS. MODELS NOW SUGGEST THAT SURFACE RIDGING WILL LINGER LONGER OVER THE REGION AND THIS WILL GIVE AN OPPORTUNITY FOR ANOTHER NIGHT OF GOOD RAD COOLING CONDITIONS IN MOST AREAS FOR THURSDAY NIGHT. SOME HIGH CLOUDS PRECEDING THE NEXT DISTURBANCE WILL AFFECT AT LEAST NORTHERN ZONES BEFORE MORNING...BUT THEY SHOULD NOT BE TOO BIG AN IMPEDIMENT TO COOLING. EXPECT A RANGE OF UPPER 30S EAST TO LOW 40S WEST BY FRIDAY MORNING. THIS IS RIGHT WITH 00Z MEX EXCEPT IN FAR NORTHWEST (DELTA) WHERE A BIT OF SOUTHERLY FLOW WILL KEEP TEMPS FROM BOTTOMING OUT LATE AT NIGHT. IN THE REALLY LONG TERM...THE GFS MODELS CONTINUES TO WANT TO BRING A RATHER STRONG COLD FRONT INTO AND THROUGH THE REGION FRIDAY THROUGH EARLY SATURDAY IN A DEVELOPING NORTHWEST UPPER FLOW REGIME. THIS SCENARIO WOULD BRING VERY LITTLE PRECIP ALONG THE FRONT WITH COOLER THAN NORMAL TEMPERATURES GETTING ENTRENCHED INTO THE REGION THROUGH AT LEAST THE END OF THE WEEK. THE GENERALLY MORE RELIABLE (AT LEAST IN THE LONG RANGE) EUROPEAN MODEL SUGGESTS THAT STRONG RIDGING OFF THE EAST COAST WILL SLOW DOWN AND AMPLIFY ENERGY COMING INTO THE PLAINS FOR LATE IN THE WORK WEEK...HOLDING UP ANY COLD FRONT BEFORE IT CAN BLAST SOUTH THROUGH HERE. THESE DIFFERENCES IN THE MODELS ARE COMPOUNDED BY EARLY NEXT WEEK AS ADDITIONAL ENERGY FORECAST TO DROP INTO THE CENTER OF THE NATION BY BOTH MODELS IS HANDLED MUCH DIFFERENTLY: THE EURO MODEL PASSES TWO RATHER POTENT STORM SYSTEMS CLOSE ENOUGH TO THE ARKLAMISS BETWEEN SUNDAY AND NEXT TUESDAY TO PRODUCE WEATHER; WHILE THE GFS JUST REINFORCES NORTHWEST FLOW ALOFT OVER THE AREA ON SUNDAY WITH A CLIPPER-TYPE SYSTEM THAT BRINGS A SHOT OF COLD AIR AND LITTLE PRECIP. GIVEN TENDENCIES OBSERVED OVER THE PAST FEW MONTHS AND THE FACT THAT LA NINA CONTINUES...THE EURO SEEMS LIKE THE WAY TO GO. THIS SOLUTION SHOULD EVENTUALLY RESULT IN A GOOD SHOT OF LATE SEASON COLD TO THE REGION...BUT PROBABLY A FEW DAYS SLOWER THAN THE GFS MODELS SUGGESTS. THE EURO ALSO WOULD BE MORE FAVORABLE FOR AT LEAST ONE BOUT OF SIGNIFICANT PRECIP WITHIN THE NEXT WEEK WHILE THE GFS DOES NOT OFFER MUCH HOPE OF THAT. ALL THE ABOVE BEING SAID...I MADE SOME CHANGES TO LATEST 00Z MEX GUIDANCE FRIDAY THROUGH NEXT MONDAY. MAIN ALTERATIONS WHERE TO BOOST TEMPERATURES FOR NEARLY ALL PERIODS IN THE MENTIONED RANGE SINCE GFS PREDICTS MAINLY BELOW NORMAL TEMPS AND NEAR-NORMAL TEMPS (HIGHS UPPER 60S TO MID 70S; LOWS IN THE 40S) LOOK MUCH MORE LIKELY. GFS POPS ARE ALL 20 PERCENT OR LESS FROM FRIDAY THROUGH MONDAY...BUT THERE DEFINITELY LOOKS TO BE MUCH MORE POTENTIAL FOR RAIN WITHIN THAT PERIOD THAN THOSE NUMBERS SUGGEST. HOWEVER...DECIDING ON THE DAY WHEN BEST CHANCES WILL COME IS BEYOND MY SKILL RIGHT NOW SO TWEAKS TO POPS WERE ONLY MINOR. /BB/ && .AVIATION...BROKEN LAYER OF CLOUDS 1800-2300FT RESULTING IN MVFR CONDITIONS THIS MORNING WILL CONTINUE MAINLY IN THE SOUTH AND WEST THROUGH MUCH OF TODAY AND LOWER TONIGHT AS A CENTER OF LOW PRESSURE DRAWS CLOSER TO THE AREA. AS A RESULT OF THE APPROACHING LOW...STRONG GUSTY SOUTHERLY WINDS 20-25KTS WITH GUSTS TO 35KTS WILL PREVAIL TODAY. SHOWERS AND A FEW THUNDERSTORMS WILL DEVELOP MAINLY IN THE WEST THIS AFTERNOON BUT A SQUALL LINE IS EXPECTED TO MOVE ACROSS THE AREA TONIGHT. THE LINE SHOULD BE IN VCTY OF GLH BY 05Z AND PROGRESS EASTWARD TO VCTY OF GTR-MEI-HBG LINE BY 12Z. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 78 60 61 40 / 54 100 41 0 MERIDIAN 78 61 64 40 / 27 100 57 2 VICKSBURG 80 59 60 37 / 74 100 29 0 HATTIESBURG 79 61 65 40 / 36 100 43 1 NATCHEZ 80 60 59 38 / 72 100 21 0 GREENVILLE 77 57 56 38 / 82 100 41 0 GREENWOOD 77 59 60 38 / 62 100 49 0 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...LAKE WIND ADVISORY UNTIL 7 AM CDT WEDNESDAY FOR MSZ030-031-033- 038-039-045-046-051-052-056>058-064>066-072>074. LAKE WIND ADVISORY UNTIL 7 AM CDT THIS MORNING FOR MSZ018-019- 025>029-032-034>037-040>044-047>050-053>055-059>063. LAKE WIND ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT WEDNESDAY FOR MSZ018-019-025>029-032-034>037-040>044-047>050-053>055- 059>063. WIND ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR MSZ018-019-025>029- 032-034>037-040>044-047>050-053>055-059>063. LA...LAKE WIND ADVISORY UNTIL 7 AM CDT THIS MORNING FOR LAZ007>009- 015-016-023>026. LAKE WIND ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT WEDNESDAY FOR LAZ007>009-015-016-023>026. WIND ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR LAZ007>009-015-016- 023>026. AR...LAKE WIND ADVISORY UNTIL 7 AM CDT THIS MORNING FOR ARZ074-075. LAKE WIND ADVISORY FROM MIDNIGHT TONIGHT TO 7 AM CDT WEDNESDAY FOR ARZ074-075. WIND ADVISORY UNTIL MIDNIGHT CDT TONIGHT FOR ARZ074-075. && $$ SHORT TERM/AVIATION: 22 LONG TERM: BB ms AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 1105 AM CDT MON MAR 17 2008 .UPDATE...WINDS...TEMPS AND DEWPOINTS REMAINING CLOSE TO HOURLY GRIDS AS MOISTURE SURGE NOW UNDERWAY INTO THE LOWER MS VALLEY. PRESSURE GRADIENT FROM E TO W ACROSS THE CWFA NEAR 6MB CURRENTLY AND THIS PATTERN SHOULD HOLD UP ACROSS THE LAKE WIND ADVY LOCATIONS THROUGH TONIGHT. UPPER LEVEL CLOUD SHIELD GRADUALLY THICKENING AS WELL. LITTLE CHANGE TO GRIDS AND UPDATED NUMBERS SHOULD BE POSTED WITH NEW ZONE PACKAGE SHORTLY JUST TO ADJUST WORDING./40/ PREVIOUS DISCUSSION FOLLOWS: SHORT TERM(TODAY THROUGH TUESDAY)...WATER VAPOR IMAGERY/RUC ANALYSIS THIS MORNING SHOWS THE CIRCULATION AROUND A DEEP CLOSED LOW OVER THE DESERT SOUTHWEST THAT WILL SWING EAST TODAY TO THE TEXAS BIG BEND AND THEN NORTHEAST TUESDAY ACROSS CENTRAL TEXAS. MODELS ARE IN AGREEMENT THAT THIS UPPER LOW WILL HELP DEVELOP A SURFACE LOW OVER SOUTHERN TEXAS THAT WILL TRACK NORTHEAST ACROSS THE ARKLATEX TUESDAY AND DRAG A COLD FRONT INTO OUR CWA TUESDAY NIGHT WITH SEVERE THUNDERSTORM POTENTIAL. FOR TODAY THOUGH...LATEST SURFACE ANALYSIS SHOWS A 1000MB LOW OVER WEST CENTRAL TEXAS WITH HIGH PRESSURE CENTERED OVER THE EASTERN SEABOARD. THE PRESSURE GRADIENT BETWEEN THESE FEATURES HAS KEPT OUR WINDS UP ALL NIGHT AND WILL RESULT IN A WARM AND BREEZY DAY TODAY. SUSTAINED WINDS OF 15 TO 25 MPH ARE EXPECTED OVER MUCH OF AREA TODAY MEETING LOCAL LAKE WIND ADVISORY CRITERIA. THE WINDS WILL BECOME LIGHTER THIS EVENING AND FALL BELOW LAKE WIND ADVISORY CRITERIA BEFORE INCREASING AGAIN AFTER MIDNIGHT AS THE LOW DRAWS CLOSER. EVEN STRONGER WINDS ARE EXPECTED TUESDAY AND A WIND ADVISORY WL LIKELY BE ISSUED LATER TODAY FOR TUESDAY AND OVER MOST OF THE CWFA. WL INCREASE AREA OF THE LAKE WIND ADVISORY THAT IS IN EFFECT FOR TODAY TO INCORPORATE ALL BUT OUR SOUTHEAST COUNTIES. THE WARM SOUTHERLY WINDS WILL BEGIN INCREASING MOISTURE BACK INTO OUR AREA TODAY. LOWER 60 DEW POINTS ARE EXPECTED BACK IN OUR SOUTHWEST ZONES BY SUN DOWN. STRENGTHENING WAA SHOULD ALLOW TEMPERATURES TO TOP OUT IN THE LOWER 80S SOUTH TO THE MID 70S NORTHEAST. TEMPERATURES WILL BE RATHER MILD TONIGHT IN THE LOWER 60S AND RISE BACK INTO THE UPPER 70S TUESDAY. GUIDANCE TEMPS WERE CLOSE AND ACCEPTED FOR TODAY AND TONIGHT BUT WERE TOO COOL IN THE EAST FOR TUESDAY. BOTH THE UPPER LOW AND DEVELOPING SURFACE LOW WILL BE STRENGTHENING TUESDAY AS THEY APPROACH OUR CWFA. A STRONGLY SHEARED ENVIRONMENT ALONG WITH A WARM MOIST AIRMASS WILL BE BACK OVER OUR AREA BY TUESDAY AFTERNOON. SOUNDINGS INDICATE A WEAKENING CAP BUT RATHER WEAK LAPSE RATES LIMITING INSTABILITY. THERE MAY BE A COUPLE OF STRONG TO SEVER STORMS IN OUR WESTERN COUNTIES AND PARISHES LATE TUESDAY AFTERNOON BUT THE MAIN FOCUS FOR SEVERE STORMS WILL BE WITH THE EXPECTED SQUALL LINE TO MOVE THROUGH TUESDAY NIGHT. /22/ .LONG TERM...MAIN FOCUS IS STILL ON THE BIG DISTURBANCE EXPECTED TO PUSH INTO THE ARKLAMISS TUESDAY NIGHT. MODELS CONTINUE TO SUGGEST THAT THE COMBINATION OF RATHER LOW INSTABILITY (DUE TO POOR ATMOSPHERIC LAPSE RATES)...HIGH AMOUNTS OF LOW LEVEL WIND SHEAR...CONCENTRATED ATMOSPHERIC LIFT...AND DEEP SHEAR VECTORS ROUGHLY PARALLEL TO THE APPROACHING COLD FRONT WILL BE THE PROPER RECIPE FOR A VIGOROUS SQUALL LINE PUSHING EAST THROUGH THE FORECAST AREA AHEAD OF THE COLD FRONT. AMBIENT SOUTHERLY WINDS AHEAD OF THE COLD FRONT WILL BE QUITE STRONG AND FREQUENT GUSTS WELL OVER 30 MPH COULD PRODUCE SOME ISOLATED LIGHT DAMAGE BEFORE STORMS EVEN ARRIVE. THE EXPECTED SQUALL LINE WILL BE ABLE TO BRING POWERFUL LOWER ATMOSPHERIC WINDS (>50 KTS AT 2500 FT) DOWN TO THE SURFACE EVEN MORE EFFICIENTLY. MODEL DEPICTIONS OF A 700 MB "DRY SLOT" GETTING ENTRAINED INTO THE ANTICIPATED NORTH TO THE SOUTH ORIENTED SQUALL LINE BEFORE WEDNESDAY MORNING SUGGESTS RAPID FORWARD-PROPAGATION OF THE FEATURE IS POSSIBLE LATE TUESDAY NIGHT...WHICH WILL FURTHER RAISE DAMAGING WIND POTENTIAL. IT IS STILL POSSIBLE THAT MINOR SURFACE INVERSIONS DEVELOPING OVER THE EASTERN HALF OF THE AREA COULD BUFFER THE GROUND FROM THE WORST OF THE WEATHER...BUT MODEL SOUNDINGS DO NOT REALLY SUGGEST THIS AND IT IS LOOKING MORE LIKELY THAT A WIDESPREAD DAMAGING WIND EVENT IS ON TAP FOR TUESDAY NIGHT. THE LEVELS OF WIND SHEAR REFERRED TO ABOVE WILL ALSO BE CONDUCIVE FOR LEWP (LINE ECHO WAVE PATTERN) SIGNATURES THAT COULD EASILY SPIN UP TORNADOES. FINALLY...HIGHER CONFIDENCE IN THE FAST PROGRESSION OF A SQUALL LINE THROUGH THE REGION FURTHER LOWERS THE POTENTIAL FOR ANY WIDESPREAD EXCESSIVE RAINFALL ISSUES (AND MODEL OUTPUT BACKS THAT UP). THE ACTUAL COLD FRONT MAY NOT COME THROUGH TILL THAT DAYLIGHT HOURS ON WEDNESDAY...BUT THE GFS MODEL SUGGESTS DRY AIR AT 700 MB WILL BE BROUGHT DOWN TO THE SURFACE BEHIND THE EASTWARD-RACING SQUALL LINE SO EFFICIENTLY THAT A SORT OF SMALL-SCALE COLD FRONT WILL BE CREATED. THUS...MOST AREAS SHOULD START OUT IN THE LOW TO MID 50S WITH CLOUDS THICKENING BACK UP AS THE MAIN COLD FRONT OOZES THROUGH AND THE MEAT OF THE UPPER LEVEL TROUGH SWINGS THROUGH. MORE RAIN WILL BE POSSIBLE IN THIS TIME FRAME WITH ISOLATED STORMS NOT OUT OF THE QUESTION IN THE FAR NORTH WHERE UPPER LEVEL DEFORMATION ASSOCIATED WITH THE UPPER LOW WILL ENHANCE LIFT. NO SEVERE WEATHER IS EXPECTED WITH THIS ACTIVITY AND ANY RAIN SHOULD BE PULLING OUT IN THE AFTERNOON (OR EARLIER). LATESTS MODELS (ESPECIALLY THE GFS) SUGGEST THAT LOW CLOUDS BUILDING BACK IN ALONG AND BEHIND THIS COLD FRONTAL PASSAGE WILL HAVE A HARD TIME CLEARING BEFORE EARLY WEDNESDAY EVENING. IF THIS IS THE CASE THEN TEMPERATURES WILL HAVE A STRUGGLE MOVING UPWARD AND I WENT WITH MUCH LOWER 00Z MEX GUIDANCE (WHICH FORECASTS HIGHS MAINLY IN THE UPPER 50S WITH GUSTY NORTHWEST WINDS). HOWEVER...THERE IS STILL AT LEAST SOME POTENTIAL FOR WARMER WEATHER ON WEDNESDAY SINCE ANY EARLIER CLEARING FROM WEST TO EAST SHOULD CAUSE TEMPS TO RESPOND UPWARD QUICKLY. WEDNESDAY NIGHT SHOULD BE A COOL ONE AS HIGH PRESSURE AND CLEAR SKIES COMBINE OVER THE ARKLAMISS IN THE WAKE OF THE STRONG FRONT. TEMPERATURES IN THE 30S ARE NOW ANTICIPATED IN MANY AREAS...BUT NO FREEZING TEMPS ARE EXPECTED AT THIS TIME. LOOK FOR A WARM UP TO START ON THURSDAY AS UPPER LEVEL RIDGING DEVELOPS OVER THE LOWER MISSISSIPPI VALLEY. MODELS ARE HAVING A RATHER TOUGH TIME WITH THE NEXT SYSTEM THAT WAS SCHEDULED TO THE IMPACT THE REGION LATE IN THE WEEK. SEVERAL PREVIOUS MODEL SOLUTIONS FROM THE GFS AND ECMWF SUGGESTED A SOUTHEAST MOVING WAVE TO AMPLIFY QUICKLY OVER THE PLAINS AND SPUR CYCLOGENESIS NEARBY OUR REGION AS A COLD FRONT MOVED TOWARD THE COAST BEFORE STALLING. THAT RECIPE WOULD HAVE SET THE STAGE FOR AT LEAST A FEW DAYS OF INCLEMENT WEATHER. NOW MODELS THINK THIS WAVE WILL NOT AMPLIFY MUCH AS IT HEADS SOUTHEAST...WITH MOST OF ITS ENERGY REMAINING NORTH OF THE LOWER MISSISSIPPI VALLEY. A FRONT COULD STILL WORK INTO THE AREA FROM THE NORTHWEST BY FRIDAY...BUT THERE WILL BE RELATIVELY LITTLE UPPER SUPPORT OR MOISTURE FOR THE PRODUCTION OF WIDESPREAD PRECIP. THIS FORECAST GENERALLY BUYS INTO THE LATEST IDEA...BUT GIVEN THE ACTIVE WEATHER PATTERN OF LATE I WOULD NOT BE COMPLETELY SURPRISED IT MODELS TRENDED BACK TO A STORMIER SOLUTION WITHIN A FEW DAYS. WE`LL SEE. I GENERALLY STUCK RIGHT WITH LATEST 00Z MEX POPS AND TEMPS THROUGH THE LONG TERM. MAIN DEVIATIONS WERE TO POPS FOR TUESDAY NIGHTS EVENT AS CONFIDENCE IS NOW HIGH ENOUGH TO GO WITH 100 PERCENTS. EXPECT TEMPERATURES TO BE A LITTLE ABOVE NORMAL THROUGH NEXT WEEKEND (ASIDE FROM THE QUICK CHILLY PERIOD BEHIND EARLY WEDNESDAY`S COLD FRONTAL PASSAGE). /BB/ && .AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH 00Z WITH BROKEN CEILINGS DROPPING TO MVFR CONDITIONS 00Z-04Z ESPECIALLY IN THE WEST. THE FOCUS WILL REMAIN ON THE INCREASING LOW LEVEL WINDS AND GUSTS OF 25-30KTS AT TIMES. HIGHEST WINDS WILL BE OVER THE NORTHWEST WITH LIGHTEST IN THE SOUTHEAST. A FEW SHRA MAY BEGIN POPPING AFTER 04Z AS WELL. /40/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 81 62 79 54 / 4 16 32 98 MERIDIAN 80 57 79 56 / 4 7 23 100 VICKSBURG 82 63 80 53 / 9 18 55 100 HATTIESBURG 82 59 79 60 / 11 16 26 100 NATCHEZ 83 65 79 53 / 9 16 51 100 GREENVILLE 77 63 76 50 / 12 29 63 100 GREENWOOD 78 63 78 54 / 7 19 57 100 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...LAKE WIND ADVISORY UNTIL 7 AM CDT TUESDAY FOR MSZ018-019-025>054- 059>062. LA...LAKE WIND ADVISORY UNTIL 7 AM CDT TUESDAY FOR LAZ007>009-015-016- 023>026. AR...LAKE WIND ADVISORY UNTIL 7 AM CDT TUESDAY FOR ARZ074-075. && $$ ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 415 AM CDT MON MAR 17 2008 .SHORT TERM...TODAY THROUGH TUESDAY...WATER VAPOR IMAGERY/RUC ANALYSIS THIS MORNING SHOWS THE CIRCULATION AROUND A DEEP CLOSED LOW OVER THE DESERT SOUTHWEST THAT WILL SWING EAST TODAY TO THE TEXAS BIG BEND AND THEN NORTHEAST TUESDAY ACROSS CENTRAL TEXAS. MODELS ARE IN AGREEMENT THAT THIS UPPER LOW WILL HELP DEVELOP A SURFACE LOW OVER SOUTHERN TEXAS THAT WILL TRACK NORTHEAST ACROSS THE ARKLATEX TUESDAY AND DRAG A COLD FRONT INTO OUR CWA TUESDAY NIGHT WITH SEVERE THUNDERSTORM POTENTIAL. FOR TODAY THOUGH...LATEST SURFACE ANALYSIS SHOWS A 1000MB LOW OVER WEST CENTRAL TEXAS WITH HIGH PRESSURE CENTERED OVER THE EASTERN SEABOARD. THE PRESSURE GRADIENT BETWEEN THESE FEATURES HAS KEPT OUR WINDS UP ALL NIGHT AND WILL RESULT IN A WARM AND BREEZY DAY TODAY. SUSTAINED WINDS OF 15 TO 25 MPH ARE EXPECTED OVER MUCH OF AREA TODAY MEETING LOCAL LAKE WIND ADVISORY CRITERIA. THE WINDS WILL BECOME LIGHTER THIS EVENING AND FALL BELOW LAKE WIND ADVISORY CRITERIA BEFORE INCREASING AGAIN AFTER MIDNIGHT AS THE LOW DRAWS CLOSER. EVEN STRONGER WINDS ARE EXPECTED TUESDAY AND A WIND ADVISORY WL LIKELY BE ISSUED LATER TODAY FOR TUESDAY AND OVER MOST OF THE CWFA. WL INCREASE AREA OF THE LAKE WIND ADVISORY THAT IS IN EFFECT FOR TODAY TO INCORPORATE ALL BUT OUR SOUTHEAST COUNTIES. THE WARM SOUTHERLY WINDS WILL BEGIN INCREASING MOISTURE BACK INTO OUR AREA TODAY. CURRENT SURFACE DEW POINTS ARE RUNNING IN THE UPPER 30S TO LOWER 40S. LOWER 60 DEW POINTS ARE EXPECTED BACK IN OUR SOUTHWEST ZONES BY SUN DOWN. CLOUDS WILL BE ON THE INCREASE TODAY AS WELL BUT ENOUGH INSOLATION COMBINED WITH STRENGTHENING WAA SHOULD ALLOW TEMPERATURES TO TOP OUT IN THE LOWER 80S SOUTH TO THE MID 70S NORTHEAST. TEMPERATURES WILL BE RATHER MILD TONIGHT IN THE LOWER 60S AND RISE BACK INTO THE UPPER 70S TUESDAY. GUIDANCE TEMPS WERE CLOSE AND ACCEPTED FOR TODAY AND TONIGHT BUT WERE TOO COOL IN THE EAST FOR TUESDAY. BOTH THE UPPER LOW AND DEVELOPING SURFACE LOW WILL BE STRENGTHENING TUESDAY AS THEY APPROACH OUR CWFA. A STRONGLY SHEARED ENVIRONMENT ALONG WITH A WARM MOIST AIRMASS WILL BE BACK OVER OUR AREA BY TUESDAY AFTERNOON. SOUNDINGS INDICATE A WEAKENING CAP BUT RATHER WEAK LAPSE RATES LIMITING INSTABILITY. THERE MAY BE A COUPLE OF STRONG TO SEVER STORMS IN OUR WESTERN COUNTIES AND PARISHES LATE TUESDAY AFTERNOON BUT THE MAIN FOCUS FOR SEVERE STORMS WILL BE WITH THE EXPECTED SQUALL LINE TO MOVE THROUGH TUESDAY NIGHT. /22/ .LONG TERM...MAIN FOCUS IS STILL ON THE BIG DISTURBANCE EXPECTED TO PUSH INTO THE ARKLAMISS TUESDAY NIGHT. MODELS CONTINUE TO SUGGEST THAT THE COMBINATION OF RATHER LOW INSTABILITY (DUE TO POOR ATMOSPHERIC LAPSE RATES)...HIGH AMOUNTS OF LOW LEVEL WIND SHEAR...CONCENTRATED ATMOSPHERIC LIFT...AND DEEP SHEAR VECTORS ROUGHLY PARALLEL TO THE APPROACHING COLD FRONT WILL BE THE PROPER RECIPE FOR A VIGOROUS SQUALL LINE PUSHING EAST THROUGH THE FORECAST AREA AHEAD OF THE COLD FRONT. AMBIENT SOUTHERLY WINDS AHEAD OF THE COLD FRONT WILL BE QUITE STRONG AND FREQUENT GUSTS WELL OVER 30 MPH COULD PRODUCE SOME ISOLATED LIGHT DAMAGE BEFORE STORMS EVEN ARRIVE. THE EXPECTED SQUALL LINE WILL BE ABLE TO BRING POWERFUL LOWER ATMOSPHERIC WINDS (>50 KTS AT 2500 FT) DOWN TO THE SURFACE EVEN MORE EFFICIENTLY. MODEL DEPICTIONS OF A 700 MB "DRY SLOT" GETTING ENTRAINED INTO THE ANTICIPATED NORTH TO THE SOUTH ORIENTED SQUALL LINE BEFORE WEDNESDAY MORNING SUGGESTS RAPID FORWARD-PROPAGATION OF THE FEATURE IS POSSIBLE LATE TUESDAY NIGHT...WHICH WILL FURTHER RAISE DAMAGING WIND POTENTIAL. IT IS STILL POSSIBLE THAT MINOR SURFACE INVERSIONS DEVELOPING OVER THE EASTERN HALF OF THE AREA COULD BUFFER THE GROUND FROM THE WORST OF THE WEATHER...BUT MODEL SOUNDINGS DO NOT REALLY SUGGEST THIS AND IT IS LOOKING MORE LIKELY THAT A WIDESPREAD DAMAGING WIND EVENT IS ON TAP FOR TUESDAY NIGHT. THE LEVELS OF WIND SHEAR REFERRED TO ABOVE WILL ALSO BE CONDUCIVE FOR LEWP (LINE ECHO WAVE PATTERN) SIGNATURES THAT COULD EASILY SPIN UP TORNADOES. FINALLY...HIGHER CONFIDENCE IN THE FAST PROGRESSION OF A SQUALL LINE THROUGH THE REGION FURTHER LOWERS THE POTENTIAL FOR ANY WIDESPREAD EXCESSIVE RAINFALL ISSUES (AND MODEL OUTPUT BACKS THAT UP). THE ACTUAL COLD FRONT MAY NOT COME THROUGH TILL THAT DAYLIGHT HOURS ON WEDNESDAY...BUT THE GFS MODEL SUGGESTS DRY AIR AT 700 MB WILL BE BROUGHT DOWN TO THE SURFACE BEHIND THE EASTWARD-RACING SQUALL LINE SO EFFICIENTLY THAT A SORT OF SMALL-SCALE COLD FRONT WILL BE CREATED. THUS...MOST AREAS SHOULD START OUT IN THE LOW TO MID 50S WITH CLOUDS THICKENING BACK UP AS THE MAIN COLD FRONT OOZES THROUGH AND THE MEAT OF THE UPPER LEVEL TROUGH SWINGS THROUGH. MORE RAIN WILL BE POSSIBLE IN THIS TIME FRAME WITH ISOLATED STORMS NOT OUT OF THE QUESTION IN THE FAR NORTH WHERE UPPER LEVEL DEFORMATION ASSOCIATED WITH THE UPPER LOW WILL ENHANCE LIFT. NO SEVERE WEATHER IS EXPECTED WITH THIS ACTIVITY AND ANY RAIN SHOULD BE PULLING OUT IN THE AFTERNOON (OR EARLIER). LATESTS MODELS (ESPECIALLY THE GFS) SUGGEST THAT LOW CLOUDS BUILDING BACK IN ALONG AND BEHIND THIS COLD FRONTAL PASSAGE WILL HAVE A HARD TIME CLEARING BEFORE EARLY WEDNESDAY EVENING. IF THIS IS THE CASE THEN TEMPERATURES WILL HAVE A STRUGGLE MOVING UPWARD AND I WENT WITH MUCH LOWER 00Z MEX GUIDANCE (WHICH FORECASTS HIGHS MAINLY IN THE UPPER 50S WITH GUSTY NORTHWEST WINDS). HOWEVER...THERE IS STILL AT LEAST SOME POTENTIAL FOR WARMER WEATHER ON WEDNESDAY SINCE ANY EARLIER CLEARING FROM WEST TO EAST SHOULD CAUSE TEMPS TO RESPOND UPWARD QUICKLY. WEDNESDAY NIGHT SHOULD BE A COOL ONE AS HIGH PRESSURE AND CLEAR SKIES COMBINE OVER THE ARKLAMISS IN THE WAKE OF THE STRONG FRONT. TEMPERATURES IN THE 30S ARE NOW ANTICIPATED IN MANY AREAS...BUT NO FREEZING TEMPS ARE EXPECTED AT THIS TIME. LOOK FOR A WARM UP TO START ON THURSDAY AS UPPER LEVEL RIDGING DEVELOPS OVER THE LOWER MISSISSIPPI VALLEY. MODELS ARE HAVING A RATHER TOUGH TIME WITH THE NEXT SYSTEM THAT WAS SCHEDULED TO THE IMPACT THE REGION LATE IN THE WEEK. SEVERAL PREVIOUS MODEL SOLUTIONS FROM THE GFS AND ECMWF SUGGESTED A SOUTHEAST MOVING WAVE TO AMPLIFY QUICKLY OVER THE PLAINS AND SPUR CYCLOGENESIS NEARBY OUR REGION AS A COLD FRONT MOVED TOWARD THE COAST BEFORE STALLING. THAT RECIPE WOULD HAVE SET THE STAGE FOR AT LEAST A FEW DAYS OF INCLEMENT WEATHER. NOW MODELS THINK THIS WAVE WILL NOT AMPLIFY MUCH AS IT HEADS SOUTHEAST...WITH MOST OF ITS ENERGY REMAINING NORTH OF THE LOWER MISSISSIPPI VALLEY. A FRONT COULD STILL WORK INTO THE AREA FROM THE NORTHWEST BY FRIDAY...BUT THERE WILL BE RELATIVELY LITTLE UPPER SUPPORT OR MOISTURE FOR THE PRODUCTION OF WIDESPREAD PRECIP. THIS FORECAST GENERALLY BUYS INTO THE LATEST IDEA...BUT GIVEN THE ACTIVE WEATHER PATTERN OF LATE I WOULD NOT BE COMPLETELY SURPRISED IT MODELS TRENDED BACK TO A STORMIER SOLUTION WITHIN A FEW DAYS. WE`LL SEE. I GENERALLY STUCK RIGHT WITH LATEST 00Z MEX POPS AND TEMPS THROUGH THE LONG TERM. MAIN DEVIATIONS WERE TO POPS FOR TUESDAY NIGHTS EVENT AS CONFIDENCE IS NOW HIGH ENOUGH TO GO WITH 100 PERCENTS. EXPECT TEMPERATURES TO BE A LITTLE ABOVE NORMAL THROUGH NEXT WEEKEND (ASIDE FROM THE QUICK CHILLY PERIOD BEHIND EARLY WEDNESDAY`S COLD FRONTAL PASSAGE). /BB/ && .AVIATION...VFR CONDITIONS WILL PREVAIL THROUGH 00Z TODAY WITH CEILINGS DROPPING TO MVFR CONDITIONS TONIGHT ESPECIALLY IN THE WEST. THE FOCUS TODAY WILL REMAIN ON THE WINDS AND GUSTS BETWEEN 14-00Z. HIGHEST WINDS WILL BE OVER THE NORTHWEST WITH LIGHTEST IN THE SOUTHEAST. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 80 62 79 54 / 4 16 32 98 MERIDIAN 79 57 79 56 / 4 7 23 100 VICKSBURG 81 63 80 53 / 9 18 55 100 HATTIESBURG 81 59 79 60 / 11 16 26 100 NATCHEZ 82 65 79 53 / 9 16 51 100 GREENVILLE 76 63 76 50 / 12 29 63 100 GREENWOOD 77 63 78 54 / 7 19 57 100 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...LAKE WIND ADVISORY FROM 9 AM THIS MORNING TO 7 AM CDT TUESDAY FOR MSZ018-019-025>054-059>062. LA...LAKE WIND ADVISORY FROM 9 AM THIS MORNING TO 7 AM CDT TUESDAY FOR LAZ007>009-015-016-023>026. AR...LAKE WIND ADVISORY FROM 9 AM THIS MORNING TO 7 AM CDT TUESDAY FOR ARZ074-075. && $$ SHORT TERM/AVIATION: 22 LONG TERM: BB ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 845 PM CDT TUE MAR 18 2008 ...MESOSCALE CONVECTIVE DISCUSSION... .UPDATE... RAINFALL CONTINUES ACROSS THE REGION. SUBSTANTIAL FLOODING WILL CONTINUE INTO WEDNESDAY MORNING WITH MODERATE TO MAJOR RIVER FLOODING EXPECTED WEDNESDAY AND LIKELY BEYOND. STRONG UPPER LOW NOW BEGINNING TO PROGRESS A BIT INTO TEXAS. ELONGATED UPPER JET ORIENTED FROM CENTRAL/EAST TEXAS THROUGH EASTERN KANSAS AND INTO THE GREAT LAKES REGION. UPPER DIFFLUENCE REMAINS PRONOUNCED ACROSS THE MIDDLE OF THE NATION. IN THE LOWER LEVELS...A LOW LEVEL JET CONTINUES TO SLOWLY SHIFT EASTWARD INTO THE LOWER MS RIVER VALLEY REGION. AT THE SFC...A COLD FRONT EXTENDS FROM JUST SOUTHEAST OF THE BOOT HEEL OF MO TO NEAR LITTLE ROCK AND TEXARKANA. A SFC LOW CONTINUES TO SLOWLY RIDE NORTHEASTWARD ALONG THIS FRONT AND IS CURRENTLY LOCATED OVER SOUTHWEST ARKANSAS. LOOKING AT THE LATEST RUC INITIALIZATIONS...FRONTOGENESIS IN BOTH THE LOW AND MID LEVELS WILL BE IN PLACE ALONG AND SOUTHEAST OF THE INTERSTATE 44 CORRIDOR THROUGH THE OVERNIGHT HOURS. THE UPPER LOW WILL BE SLOW TO TRAVERSE TEXAS...LIFTING TO THE EAST NORTHEAST OVERNIGHT. THE UPPER LOW OVER TEXAS WILL WEAKEN A BIT AS IT DOES SO...JOINING THE NORTHERN STREAM WEDNESDAY MORNING. THIS WILL RESULT IN A SLOW END TO OUR LIGHT TO MODERATE RAINFALL. EASTWARD PROGRESS OF THE BACK EDGE OF THE THIS RAINFALL WILL BE SLOW TO NEGLIGIBLE OVER THE NEXT SEVERAL HOURS...WAITING UNTIL THE AFOREMENTIONED SFC LOW IS EAST OF THE AREA AND THE UPPER LOW ACCELERATES TO THE EAST NORTHEAST. STRONG UPPER SUPPORT AND DEEP CONVERGENCE SHOULD MAINTAIN A NEARLY SOLID SHIELD OF RAINFALL TONIGHT. THE GOING FORECAST OF ONE TO THREE INCHES OF RAINFALL TONIGHT LOOKS GOOD...HIGHER AMOUNTS OF THREE TO FIVE INCHES ARE POSSIBLE OVER SOUTH CENTRAL MISSOURI. GAGAN && .DISCUSSION... HEAVY RAIN CONTINUES ACROSS SOUTHWEST AND CENTRAL MISSOURI THIS AFTERNOON. THOUGH WE HAVE SEEN TREMENDOUS RAINFALL AMOUNTS SO FAR...WE STILL HAVE A PERIOD OF HEAVY RAINFALL THAT WILL MOVE UP INTO THE AREA FROM NORTHWEST ARKANSAS AND EASTERN OKLAHOMA. ANY ADDITIONAL RAINFALL WILL ONLY MAKE FLOODING MATTERS WORSE. SHORT TERM (TONIGHT THROUGH THURSDAY)... FRONT EXTENDS FROM SURFACE LOW OVER SOUTH CENTRAL ARKANSAS NORTHEAST INTO THE MISSOURI BOOT HEEL THIS AFTERNOON. PROFILER DATA OVER SOUTHWEST ARKANSAS CONTINUES TO SHOW A STRONG 50KT LOW LEVEL JET EXTENDING FROM SOUTHWEST ARKANSAS UP INTO SOUTHEAST MISSOURI. MOISTURE IS RIDING UP ALONG THIS BOUNDARY INTO NORTHEAST OKLAHOMA/NORTHWEST ARKANSAS...INTO MOST OF THE CWA. UPPER LOW STILL DOWN OVER SOUTHWEST MISSOURI. SO THE MOISTURE TRAIN WILL STAY IN TACT OVER NIGHT. SERIOUS MAJOR TO RECORD FLOODING IS IN THE PROCESS OF COMING TO FRUITION. HEAVY RAIN WILL CONTINUE OVERNIGHT WITH AN ADDITIONAL 1.5-2.5 INCHES EXPECTED ALONG THE INTERSTATE 44 CORRIDOR. HPC QPF GUIDANCE SHOWING ANOTHER 2-3 INCHES EXPECTED FOR COMMUNITIES SOUTH AND EAST OF INTERSTATE 44 FOR TONIGHT. LATEST RUC GUIDANCE SHOWING A WAVE ALONG THE FRONT PUSHING INTO SOUTHERN MISSOURI THIS EVENING. FLASH FLOOD WARNINGS ARE WILL MOST LIKELY BE EXTENDED THROUGH THE OVERNIGHT AREAS TO REFLECT THESE PRECIP AMOUNTS. UPPER LOW OPENS AFTER MIDNIGHT AND TRACKS ACROSS SOUTHEAST MISSOURI WEDNESDAY MORNING. PRECIPITATION WILL END FROM WEST TO EAST WEDNESDAY MORNING. CLAYCOMB LONG TERM (FRIDAY THROUGH TUESDAY)... IN THE LONG TERM...A PROGRESSIVE PATTERN DOMINATED BY NORTHWEST FLOW ALOFT WILL DOMINATE OUR WEATHER PATTERN. SEVERAL UPPER LEVEL DISTURBANCES WILL QUICKLY PROGRESS THROUGH THIS FLOW...EACH HAVING AT LEAST A MINOR EFFECT ON OUR SENSIBLE WEATHER. THE NICEST DAY DURING THE PERIOD WILL LIKELY BE FRIDAY AS LOW PRESSURE TO THE NORTHWEST ISSUES A WARM AIR ADVECTION REGIME INTO THE AREA BRIEFLY. THIS LOW WILL BE QUICK TO MOVE THROUGH...LARGELY AFFECTING NORTHERN MISSOURI AND PERHAPS BRINGING A CHANCE FOR LIGHT SHOWERS TO OUR NORTHERN CWA. THE LOW LEVELS LOOK TO BE QUITE DRY BUT WE MAY HAVE ENOUGH LIFT AND MOISTURE IN THE MID LEVELS TO CREATE A FEW RAIN SHOWERS. A COLD FRONT SWEEPS THROUGH ON THE BACK SIDE OF THIS SYSTEM WITH MODERATE COLD AIR ADVECTION IN ITS WAKE. ANOTHER UPPER LEVEL IMPULSE DIVES SOUTHEAST BY LATE SATURDAY. THE ECMWF IS MORE AGGRESSIVE WITH PRECIP FOR THIS SYSTEM. WITH THE AMOUNT OF MID LEVEL LIFT AND THE JET PATTERN PRESENT...THIS BECOMES BELIEVABLE. HOWEVER...THERE IS ONCE AGAIN A QUESTION OF JUST HOW MUCH MOISTURE WILL BE AVAILABLE. IT APPEARS THAT THE GULF WILL OPEN UP BY LATE MONDAY AND SLIGHTLY WARMER TEMPERATURES ALONG WITH MORE SIGNIFICANT MOISTURE WILL BE BROUGHT NORTH. THE ECMWF HAS BEEN CONSISTENT IN BRINGING IN A WELL DEVELOPED STORM SYSTEM WITH A CUTOFF LOW AT 500 HPA. THE GFS ON THE OTHER HAND...HAS A WEAK WAVE IN THE UPPER FLOW MOVING THROUGH THE GREAT LAKES REGION. HAVE TRENDED TOWARD THE ECMWF AND HAVE CHANCE POPS IN THE GRIDS FOR THE MONDAY/TUESDAY TIME FRAME WITH THE MENTION OF THUNDER. AT THIS TIME...IT APPEARS THERE WOULD BE SIGNIFICANT COLD AIR BROUGHT IN WITH THIS SYSTEM. SNOW DOES NOT APPEAR LIKELY...BUT CAN NOT BE COMPLETELY RULED OUT. FUTURE MODEL RUNS WILL PROVIDE MORE DETAIL INTO THIS PORTION OF THE FORECAST. BARJENBRUCH && .AVIATION... FOR THE 0000 UTC KSGF/KJLN TAFS...PERIODS OF MODERATE HEAVY RAIN THIS EVENING WITH SCATTERED THUNDERSTORMS. IFR CONDITIONS SHOULD PERSIST. WENT AHEAD WITH LOCAL RULE OF THUMB WITH 850MB THERMAL TROUGH LIFTING CEILINGS. GETS PRETTY CLOSE TO THE JLN TERMINAL AROUND 03Z THIS EVENING. IFR CONDITIONS FOR THE SGF TERMINAL PROBABLY UNTIL AFTER MIDNIGHT. KEEPING MVFR CONDITIONS UNTIL WEDNESDAY MORNING WHERE CONDITIONS SHOULD SCATTER OUT. ALL DEPENDS THOUGH ON HOW THE UPPER LOW TRACKS OVERNIGHT. GCC && .CLIMATE... RECORD DAILY RAINFALL FOR TODAY SITE AMOUNT YEAR JOPLIN 1.42 1984 SPRINGFIELD 2.79 1889 VICHY/ROLLA 1.33 1944 WEST PLAINS 1.29 1975 LD && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH UNTIL 7 AM CDT WEDNESDAY FOR MOZ055>058- 066>071-077>083-088>098-101>106. KS...FLASH FLOOD WATCH UNTIL 7 AM CDT WEDNESDAY FOR KSZ073-097-101. && $$ mo AREA FORECAST DISCUSSION...AVIATION UPDATE NATIONAL WEATHER SERVICE SPRINGFIELD MO 615 PM CDT TUE MAR 18 2008 .DISCUSSION... HEAVY RAIN CONTINUES ACROSS SOUTHWEST AND CENTRAL MISSOURI THIS AFTERNOON. THOUGH WE HAVE SEEN TREMENDOUS RAINFALL AMOUNTS SO FAR...WE STILL HAVE A PERIOD OF HEAVY RAINFALL THAT WILL MOVE UP INTO THE AREA FROM NORTHWEST ARKANSAS AND EASTERN OKLAHOMA. ANY ADDITIONAL RAINFALL WILL ONLY MAKE FLOODING MATTERS WORSE. SHORT TERM (TONIGHT THROUGH THURSDAY)... FRONT EXTENDS FROM SURFACE LOW OVER SOUTH CENTRAL ARKANSAS NORTHEAST INTO THE MISSOURI BOOT HEEL THIS AFTERNOON. PROFILER DATA OVER SOUTHWEST ARKANSAS CONTINUES TO SHOW A STRONG 50KT LOW LEVEL JET EXTENDING FROM SOUTHWEST ARKANSAS UP INTO SOUTHEAST MISSOURI. MOISTURE IS RIDING UP ALONG THIS BOUNDARY INTO NORTHEAST OKLAHOMA/NORTHWEST ARKANSAS...INTO MOST OF THE CWA. UPPER LOW STILL DOWN OVER SOUTHWEST MISSOURI. SO THE MOISTURE TRAIN WILL STAY IN TACT OVER NIGHT. SERIOUS MAJOR TO RECORD FLOODING IS IN THE PROCESS OF COMING TO FRUITION. HEAVY RAIN WILL CONTINUE OVERNIGHT WITH AN ADDITIONAL 1.5-2.5 INCHES EXPECTED ALONG THE INTERSTATE 44 CORRIDOR. HPC QPF GUIDANCE SHOWING ANOTHER 2-3 INCHES EXPECTED FOR COMMUNITIES SOUTH AND EAST OF INTERSTATE 44 FOR TONIGHT. LATEST RUC GUIDANCE SHOWING A WAVE ALONG THE FRONT PUSHING INTO SOUTHERN MISSOURI THIS EVENING. FLASH FLOOD WARNINGS ARE WILL MOST LIKELY BE EXTENDED THROUGH THE OVERNIGHT AREAS TO REFLECT THESE PRECIP AMOUNTS. UPPER LOW OPENS AFTER MIDNIGHT AND TRACKS ACROSS SOUTHEAST MISSOURI WEDNESDAY MORNING. PRECIPITATION WILL END FROM WEST TO EAST WEDNESDAY MORNING. CLAYCOMB LONG TERM (FRIDAY THROUGH TUESDAY)... IN THE LONG TERM...A PROGRESSIVE PATTERN DOMINATED BY NORTHWEST FLOW ALOFT WILL DOMINATE OUR WEATHER PATTERN. SEVERAL UPPER LEVEL DISTURBANCES WILL QUICKLY PROGRESS THROUGH THIS FLOW...EACH HAVING AT LEAST A MINOR EFFECT ON OUR SENSIBLE WEATHER. THE NICEST DAY DURING THE PERIOD WILL LIKELY BE FRIDAY AS LOW PRESSURE TO THE NORTHWEST ISSUES A WARM AIR ADVECTION REGIME INTO THE AREA BRIEFLY. THIS LOW WILL BE QUICK TO MOVE THROUGH...LARGELY AFFECTING NORTHERN MISSOURI AND PERHAPS BRINGING A CHANCE FOR LIGHT SHOWERS TO OUR NORTHERN CWA. THE LOW LEVELS LOOK TO BE QUITE DRY BUT WE MAY HAVE ENOUGH LIFT AND MOISTURE IN THE MID LEVELS TO CREATE A FEW RAIN SHOWERS. A COLD FRONT SWEEPS THROUGH ON THE BACK SIDE OF THIS SYSTEM WITH MODERATE COLD AIR ADVECTION IN ITS WAKE. ANOTHER UPPER LEVEL IMPULSE DIVES SOUTHEAST BY LATE SATURDAY. THE ECMWF IS MORE AGGRESSIVE WITH PRECIP FOR THIS SYSTEM. WITH THE AMOUNT OF MID LEVEL LIFT AND THE JET PATTERN PRESENT...THIS BECOMES BELIEVABLE. HOWEVER...THERE IS ONCE AGAIN A QUESTION OF JUST HOW MUCH MOISTURE WILL BE AVAILABLE. IT APPEARS THAT THE GULF WILL OPEN UP BY LATE MONDAY AND SLIGHTLY WARMER TEMPERATURES ALONG WITH MORE SIGNIFICANT MOISTURE WILL BE BROUGHT NORTH. THE ECMWF HAS BEEN CONSISTENT IN BRINGING IN A WELL DEVELOPED STORM SYSTEM WITH A CUTOFF LOW AT 500 HPA. THE GFS ON THE OTHER HAND...HAS A WEAK WAVE IN THE UPPER FLOW MOVING THROUGH THE GREAT LAKES REGION. HAVE TRENDED TOWARD THE ECMWF AND HAVE CHANCE POPS IN THE GRIDS FOR THE MONDAY/TUESDAY TIME FRAME WITH THE MENTION OF THUNDER. AT THIS TIME...IT APPEARS THERE WOULD BE SIGNIFICANT COLD AIR BROUGHT IN WITH THIS SYSTEM. SNOW DOES NOT APPEAR LIKELY...BUT CAN NOT BE COMPLETELY RULED OUT. FUTURE MODEL RUNS WILL PROVIDE MORE DETAIL INTO THIS PORTION OF THE FORECAST. BARJENBRUCH && .AVIATION... FOR THE 0000 UTC KSGF/KJLN TAFS...PERIODS OF MODERATE HEAVY RAIN THIS EVENING WITH SCATTERED THUNDERSTORMS. IFR CONDITIONS SHOULD PERSIST. WENT AHEAD WITH LOCAL RULE OF THUMB WITH 850MB THERMAL TROUGH LIFTING CEILINGS. GETS PRETTY CLOSE TO THE JLN TERMINAL AROUND 03Z THIS EVENING. IFR CONDITIONS FOR THE SGF TERMINAL PROBABLY UNTIL AFTER MIDNIGHT. KEEPING MVFR CONDITIONS UNTIL WEDNESDAY MORNING WHERE CONDITIONS SHOULD SCATTER OUT. ALL DEPENDS THOUGH ON HOW THE UPPER LOW TRACKS OVERNIGHT. GCC && .CLIMATE... RECORD DAILY RAINFALL FOR TODAY SITE AMOUNT YEAR JOPLIN 1.42 1984 SPRINGFIELD 2.79 1889 VICHY/ROLLA 1.33 1944 WEST PLAINS 1.29 1975 LD && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR MOZ055>058- 066>071-077>083-088>098-101>106. KS...FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR KSZ073-097-101. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTH PLATTE NE 1028 AM CDT MON MAR 17 2008 .UPDATE... SNOW DECREASING RAPIDLY AS STRONG MID LEVEL FGEN BAND WEAKENS. KEPT ERN MOST COUNTIES HEADLINES GOING FOR NOW...BUT WILL LIKELY CANCEL THOSE SOON. 12Z RUC INDICATING SOME POTENTIAL FOR REDEVELOPMENT THIS AFTERNOON...THOUGH NRN STREAM SHOULD BEGIN TO DOMINATE AND DOWNGLIDE SHOULD TAKE OVER. WILL RE-EVALUATE THIS AS WELL. && .PREV DISCUSSION... /ISSUED 335 AM CDT MON MAR 17 2008/ DISCUSSION... STRONG LIFT FROM FRONTO BAND HAS BEEN REALIZED AS FCST BY MODELS PAST FEW DAYS...THOUGH LOCATION HAS DRIFTING FARTHER SOUTH THAN EARLIER GUIDANCE. IMPRESSIVE AMOUNTS ALREADY UNDER THE MAIN BAND WITH AT LEAST AN INCH PER HOUR HERE AT LBF 3 OF LAST 4 HOURS. EXPECT HEAVIEST SNOW BAND TO BE FROM IML TO LBF TO BBW FROM MOSAIC PAST FEW HOURS. CONVECTIVE RETURNS MOVING UP FROM W.KS IS VERY CONCERNING AS THIS MERGES WITH PRESENT BAND OR CREATES IS OWN SWATH OF HEAVIER PCPN. WILL DROP FAR NW CORNER FROM ADV AND UPGRADE FAR SE CWA INTO WARNING WITH APPROACHING FEATURE TO THE SOUTH. WILL HAVE TO ACCUMULATE THE SNOW THROUGH MID MORNING AS BUFKIT SOUNDINGS ARE INDICATING THE DARKENING FEATURE ACROSS NW NMEX WILL MOVE OVER CWA BY LATE MORNING AND ERODE THE MOISTURE FROM DENDRITIC LAYER OVER MUCH OF SOUTHERN CWA AND EITHER TURN TO DRIZZLE OR VERY LIGHT SNOW SO HAVE INTRODUCED THIS TO WX GRIDS. THIS IS MOST LIKELY ASSOC WITH EPV ON NOSE OF STRONGER JET MAX STRENGTHENING ON LEADING SIDE OF TROF AND THERE HAS BEEN AN INCREASE IN LTG INTO SW KS AS A RESULT. THIS MIX OF PCPN WILL CONTINUE TO ENHANCE THE WARNING THROUGH THE AFTERNOON IF NEEDED AND WILL NOT ALTER ENDING TIME ATTM...HOWEVER IF TREND OF 06Z MODELS ARE TO BE BELIEVED EVENT MOST LIKELY WILL BE OVER BY NEXT ZONE ISSUANCES. SNOW COVER WILL AFFECT TEMPS FCST AT LEAST NEXT TWO DAYS AND HAVE DROPPED TEMPS IN SE THIRD OF CWA. HAD MINIMAL TIME TO LOOK BEYOND FIRST PART OF FCST AND MADE SOME MINOR TWEAKS WITH NEXT PCPN EVENT HEADING TOWARD N.CWA WED NIGHT INTO THURSDAY. AVIATION... TODAY...POWERFUL FRONTOGENETIC BAND OF SNOW AND LIFR ALIGNED SOUTHWEST TO NORTHEAST FROM KIML TO SOUTH OF KONL IS EXPECTED TO DRIFT SLOWLY EAST THIS MORNING. AREAS NORTHWEST OF THE HEAVY SNOW SHOULD EXPERIENCE MVFR AND EVEN VFR CONDITIONS. CONDITIONS SHOULD IMPROVE TO VFR THIS EVENING WITH MVFR PERHAPS CONTINUING ACROSS A LINE FROM KOGA TO KONL AND SOUTHEAST. && .LBF WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING UNTIL 7 PM CDT THIS EVEN 026>029-038. SNOW ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NEZ006-007. && $$ DP/CC/JWS ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 900 PM EDT TUE MAR 18 2008 .SYNOPSIS...AN AREA OF HIGH PRESSURE OFF THE EAST COAST...WILL BRING INCREASING HUMIDITY OVERNIGHT...AS SOUTHERLY WINDS STRENGTHEN OVER THE AREA. A STRONG STORM SYSTEM OVER THE CENTRAL AND SOUTHERN PLAIN... WILL TRACK NORTHEAST THROUGH THE OHIO VALLEY LATE WEDNESDAY. THE TRAILING COLD FRONT WILL PUSH EAST ACROSS NORTH CAROLINA WEDNESDAY EVENING. HIGH PRESSURE WILL BRING COOL DRY CONDITIONS BACK TO THE REGION THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 900 PM TUESDAY... THIS EVENING... LATEST IR IMAGERY SHOWS A STEADY FLUX OF LOW-LEVEL MOISTURE (CLOUD BASES 2 TO 6KFT) STREAMING FROM OFF THE FLORIDA SE COAST... NORTHWEST THROUGH THE SAVANNAH VALLEY...AND INTO NORTH CAROLINA. THIS AREA OF STRATUS LINES UP WELL WITH THE RUC ANALYSIS OF GOOD 925MB SPEED CONVERGENCE OF 30 TO 35KTS FROM THE SOUTH. AS A RESULT...SKIES WILL REMAIN MOSTLY CLOUDY FOR THE REMAINDER OF THE EVENING... AS THE MID AND HIGH CLOUDS DRIFT EAST OF THE AREA. MEANWHILE AT THE SURFACE...A PSEUDO WARM FRONT...PRIMARILY A DEWPOINT BOUNDARY...HAS JUST BEGUN TO PUSH NORTH INTO THE NORTHERN TIER COUNTIES. MODELS WERE OVERZEALOUS THAN REALITY IN THE TIMING OF THIS MODERATION IN AIRMASS. HOWEVER AS THE SURFACE HIGH CONTINUES TO PUSH FURTHER OFFSHORE...THE STRENGTHENING SOUTHERLY RETURN FLOW (5 TO 10KTS) WILL ALLOW FOR FURTHER DEWPOINT RECOVERY...WITH DEWPOINTS CLIMBING INTO THE LOWER 50S ACROSS THE SOUTH...TO MID 40S ACROSS THE NORTH. OVERNIGHT... WAA/ISENTROPIC LIFT WILL INCREASE FROM WEST TO EAST OVERNIGHT...AS RIDGE ALOFT SHIFTS EAST AND OFFSHORE. EXPECT CLOUDS TO THICKEN AND LOWER OVERNIGHT...HOWEVER LITTLE IN THE WAY OF PRECIP THROUGH 12Z...AS STRONG MID LEVEL SUBSIDENCE CONTINUES TO LOWER WITH A STABLE BL. WILL REMOVE LOW CHANCE POPS ACROSS THE WESTERN HALF OF THE FORECAST AREA. THE COMBINATION OF THE CLOUDS... INCREASING MOISTURE... AND SURFACE WINDS REMAINING AT 10-15 MPH OVERNIGHT... WILL KEEP LOW TEMPERATURES A FEW DEGREES ABOVE GUIDANCE...IN THE LOWER TO MID 50S...WITH THE COOLEST READINGS IN THE NORTHEAST. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... AS OF 145 PM THIS AFTERNOON... MODELS ARE IN GENERAL AGREEMENT WITH THE STORM TRACK THROUGH THE LOWER TO MID MISSISSIPPI VALLEY REGION NORTHEAST THROUGH THE OHIO VALLEY THIS PERIOD. THIS KEEPS THE HEAVY TO EXCESSIVE RAINFALL WEST OF THE MOUNTAINS WITH THIS SYSTEM. THERE IS ALSO GENERAL AGREEMENT WITH THE TIMING OF THE ASSOCIATED COLD FRONTAL PASSAGE ACROSS CENTRAL NC... SUGGESTING THE MAIN BAND OF CONVECTION WILL AFFECT THE REGION BEGINNING IN THE WESTERN PIEDMONT (LATE AFTERNOON)... AND PROGRESSIVELY PUSHING EAST ACROSS CENTRAL NC BY MIDNIGHT. AS FAR AS THE SEVERE WEATHER POTENTIAL AND QPF... MUCH OF OUR REGION WILL BE IN A SLIGHT RISK OF SEVERE THUNDERSTORMS ASSOCIATED WITH THE EXPECTED CONVECTIVE LINE (WITH THE MAIN THREAT EXPECTED TO BE BOWING LINE SEGMENTS THAT MAY PRODUCE ISOLATED WIND DAMAGE). THE LATEST GUIDANCE CONTINUED TO SHOW THE MAIN UPPER DYNAMICS WILL BE IN A GRADUAL WEAKENING MODE AS THEY PASS JUST TO OUR WEST AND NORTH LATE WEDNESDAY. THE POTENT MID LEVEL LOW SEEN ON WATER VAPOR THIS AFTERNOON OVER NORTHERN MEXICO IS FORECAST TO DE-AMPLIFY SOME AS IT LIFTS NORTHEAST TOWARD THE OHIO VALLEY AS AN OPEN WAVE. HOWEVER... STRONG HEIGHT FALLS (180 TO 240 METERS AT H5)... COMBINED WITH VERY STRONG SPEED SHEAR WITH HEIGHT AND FAVORABLE UPPER JET POSITION OVER OUR REGION SUGGEST VERY STRONG FORCING ALONG THE LINE. THE MODEL FORECASTS OF A 50-60KT LOW LEVEL JET AT H85 POINT TOWARD STRONG WIND GUSTS TO THE SURFACE WITH ANY DEEP CONVECTION ALONG THE LINE. ISOLATED SEVERE CONVECTIVE WIND GUSTS IN BOWING LINE SEGMENTS AS THE LINE PUSHES THROUGH THE REGION WILL BE POSSIBLE. LIMITING FACTORS TO A MAJOR SEVERE OUTBREAK INCLUDE LIMITED INSTABILITY ESPECIALLY IN THE WEST AND NORTH PIEDMONT WHERE CLOUDS SHOULD KEEP TEMPS IN CHECK. BETTER INSTABILITY IN THE SOUTH AND EAST MAY ENHANCE THE SEVERE POTENTIAL THERE. WHILE MUCH OF THE DEEP SUBTROPICAL MOISTURE WILL HAVE BEEN WRUNG OUT OVER AND WEST OF THE APPALACHIANS TONIGHT AND WEDNESDAY... THERE WILL BE A NARROW BAND OF DEEP MOISTURE (PW`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nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1048 PM EDT MON MAR 17 2008 .SYNOPSIS...SURFACE HIGH PRESSURE EXTENDING DOWN THE EASTERN SEABOARD WILL SHIFT OFFSHORE OVERNIGHT...WHILE RIDGING ALOFT CONTINUES TO BUILD OVER THE AREA ON TUESDAY. MEANWHILE...A LOW PRESSURE SYSTEM WILL DEVELOP OVER THE DEEP SOUTH...AND TRACK QUICKLY TO THE NORTHEAST ON WEDNESDAY...WITH THE ATTENDANT COLD FRONT CROSSING NORTH CAROLINA LATE WEDNESDAY. && .NEAR TERM /THROUGH TUESDAY/... AS OF 1045 PM MONDAY...SURFACE RIDGE CONTINUES TO EXTEND FROM THE EASTERN GREAT LAKES THROUGH THE CAROLINAS...WITH A SLACK GRADIENT AND LOW DEW POINTS OVER CENTRAL NORTH CAROLINA. THE HIGH WILL CONTINUE TO DRIFT SLOWLY EAST OVERNIGHT...AS THE UPPER RIDGE AXIS SHIFTS EAST AS WELL. CIRRUS AND A FEW AC WERE SPILLING OVER THE RIDGE INTO CENTRAL NORTH CAROLINA AND THIS SHOULD CONTINUE OVERNIGHT...WITH THE RUC AND THE NAM UPPER-LEVEL MOISTURE FORECASTS SHOWING THE CIRRUS OVER EASTERN TENNESSEE HOLDING TOGETHER SOME AS IT MOVES EAST ACROSS THE STATE. SATELLITE TRENDS AS OF LATE EVENING SHOWED THIS TO BE VERIFYING WELL. EXPECT THE CIRRUS TO THIN AS IT MOVES PAST THE RIDGE AXIS SO...AT MOST...ANTICIPATE PARTLY CLOUDY CONDITIONS OR MOSTLY CLEAR SKIES IN THE COASTAL PLAIN BECOMING PARTLY CLOUDY OVERNIGHT. DESPITE AMPLE 850MB MOISTURE OVER THE GULF COAST STATES...VERY DRY 850MB AIR WAS PRESENT ON THE 00Z RAOB ANALYSIS FROM EASTERN TENNESSEE AND NORTHERN GEORGIA NORTH THROUGH THE CAROLINAS AND VIRGINIA. AS THE RIDGE MOVES EAST...INCREASING MOISTURE WILL GRADUALLY WORK ITS WAY INTO THE STATE...BUT THE DRY AIR INITIALLY WILL BE DIFFICULT TO OVERCOME. TRENDS OF THE GFS BUFR SOUNDINGS AND MOS GUIDANCE IS FOR SLIGHTLY FEWER CLOUDS AND WARMER DAYTIME HIGHS TUESDAY...AND THIS SEEMS REASONABLE AS THE SATELLITE DPI LOW CLOUD IMAGES CORRELATING WITH SURFACE OBSERVATIONS TOWARD THE FLORIDA GULF COAST...AND SOUTHERN GEORGIA AND ALABAMA...SHOW LITTLE IN THE WAY OF LOW-LEVEL CLOUD FORMATION AT PRESENT. AT THIS POINT OPTED TO SHOW A MINOR INCREASE IN DAYTIME HIGHS FOR TUESDAY... ABOUT A CATEGORY PARTICULARLY IN NORTHERN ZONES...AND IF THERE CONTINUES TO BE INCREASING EVIDENCE OF BETTER MIXING AND FEWER LOW CLOUDS FOR TUESDAY HIGHS MAY END UP BEING NUDGED UP EVEN MORE WITH UPCOMING FORECAST ISSUANCES. GOOD LOW-LEVEL MIXING SHOULD ALLOW FOR A FEW WIND GUSTS IN THE TEENS KT BASED ON INCREASING 925MB WINDS TUESDAY AFTERNOON. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...SOUTH WINDS ON THE INCREASE TUESDAY NIGHT AHEAD OF APPROACHING FRONT. LOW LEVEL THICKNESS AND LOW CLOUDS ON THE INCREASE AS WELL. THUS OVERNIGHT LOWS SHOULD OCCUR BEFORE MIDNIGHT AND TEMPERATURES SLOWLY RISE TO MID 50S TO NEAR 60 BY SUNRISE WEDNESDAY. STILL MINOR TIMING DIFFERENCES IN ONSET OF PRECIPITATION WEDNESDAY BUT LIKELY NOTHING SIGNIFICANT NOR WIDESPREAD BEFORE MID AFTERNOON. ALL RAIN SHOULD EXIT MOST OF CENTRAL NORTH CAROLINA BEFORE MIDNIGHT WEDNESDAY NIGHT. STORM RELATIVE HELICITY FORECAST ABOVE 500 WITH WINDS IN EXCESS OF 50 KNOTS BELOW 5000 FEET DURING THE EVENT. FORECAST SOUNDINGS ARE A BIT MORE STABLE WITH THIS SYSTEM THEN ON MARCH FIFTEENTH. ALTHOUGH THE SEVERE THREAT IS NOT ZERO...IT DOES APPEAR LESSENED COMPARED TO THE PREVIOUS EVENT. FORECAST RAINFALL AMOUNTS OF FOUR TO SIX TENTHS OF AN INCH COULD BE SLIGHTLY ON THE LOW SIDE. SOME LOCAL AMOUNTS WILL EXCEED ONE INCH IN THE STRONGER THUNDERSTORMS. WITH PRECIPITATION A BIT DELAYED FROM THINKING OF SUNDAY...AFTERNOON HIGHS SHOULD BE LOW 70S WEST TO UPPER 70S EAST. WEDNESDAY NIGHT LOWS IN THE 40S. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 3 PM MONDAY...A BACK DOOR COLD FRONT HINTED AT ON SOME MODELS YESTERDAY FOR THE COMING WEEKEND LOOKS MORE CERTAIN AT THIS TIME. FRONT SLIPS SOUTH DURING THE DAY SATURDAY AND NORTHEAST FLOW IS EXPECTED TO PERSIST INTO SUNDAY NIGHT. IF LOW STRATUS ADVECTS INTO THE STATE SUNDAY NIGHT AS THE GFS MODEL SUGGESTS TEMPERATURES COULD STRUGGLE TO RISE MUCH PAST 50 DEGREES...AND DRIZZLE POSSIBLE AS WELL. WILL STAY A LITTLE ON THE OPTIMISTIC SIDE AT THIS TIME AND ADDRESS THIS IN THE FUTURE. WINDS SHIFT TO NORTHWEST TO WEST MONDAY BUT ENOUGH BOUNDARY LAYER MOISTURE REMAINS TO DEVELOP AFTERNOON CUMULUS MONDAY AND PERHAPS BECOME MOSTLY CLOUDY. AFTERNOON HIGHS IN THE 60S EXCEPT 50S OR LOWER SUNDAY AND MONDAY. MORNING LOWS GENERALLY WITHIN A FEW DEGREES OF 40. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... AS OF 1045 PM MONDAY...SFC HIGH PRESSURE OVER NEW ENGLAND WILL CONTINUE TO RIDGE INTO CENTRAL NORTH CAROLINA TONIGHT...WITH THE RIDGE AXIS GRADUALLY SHIFTING EAST OVERNIGHT. DRY LOW LEVELS ALONG WITH A WEAK PRESSURE GRADIENT WILL SET THE STAGE FOR LIGHT WINDS AND PASSING MID AND MAINLY HIGH LEVEL CLOUDS. AS THE HIGH SHIFTS FURTHER OFFSHORE TUESDAY...MOISTURE WILL BEGIN TO INCREASE FROM THE SOUTH UNDER RETURN FLOW. GUIDANCE HAS BACKED OFF ON THE DEGREE OF ISENTROPIC LIFT AND RESULTANT LOW CLOUDS TOMORROW. THE LATEST FORECAST REFLECTS A LATER ARRIVAL OF STRATOCUMULUS...WITH ANY CIGS EXPECTED TO STAY VFR AND OCCUR AROUND 18Z AT GSO/INT AND 20-23Z AT RDU/FAY/RWI. MVFR CIGS WILL BEGIN TO ENTER INT CLOSE TO 00Z AS STRONGER ISENTROPIC LIFT DEVELOPS. -JFB/BLS WITH THE APPROACH OF A WARM FRONT FROM THE SOUTH...MVFR CONDITIONS ARE LIKELY OVER CENTRAL NC TUE NIGHT AND POSSIBLY LOWERING TO IFR A FEW HOURS WED MORNING. CONDITIONS MIX TO VFR WEATHER AHEAD OF A COLD FRONT FROM THE WEST AND LOWER LEVEL WINDS STRENGTHEN TO 50 KTS WITHIN 3 THSD FT OF THE SURFACE LATE WED. THE COLD FRONT IS LIKELY TO BE ACCOMPANIED BY A LINE OF HEAVY SHOWERS OR TSTMS OVER CENTRAL NC WED EVENING. FOLLOWING THE COLD FRONT EARLY WED NIGHT...VFR CONDITIONS ARE LIKELY WITH DRY AIR FROM HIGH PRESSURE DRIFTING EAST FROM THE TENNESSEE VALLEY. HIGH PRESSURE DRIFTS SLOWLY EAST THE NEXT TWO DAYS AND OFF THE COAST AND SHOULD MAINTAIN VFR WEATHER THROUGH THE END OF THE WEEK. -RFG && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLS NEAR TERM...DJF SHORT TERM...RLH LONG TERM...RLH AVIATION...BLS/JFB/RFG nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 751 PM EDT MON MAR 17 2008 .SYNOPSIS...AN AREA OF HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH TONIGHT. THE HIGH WILL SHIFT OFFSHORE TUESDAY...IN ADVANCE OF A COLD FRONT THAT WILL CROSS CENTRAL NORTH CAROLINA WEDNESDAY AFTERNOON AND EVENING. && .NEAR TERM /THROUGH TUESDAY/... AS OF 750 PM MONDAY...SURFACE RIDGE CONTINUES TO EXTEND FROM THE EASTERN GREAT LAKES THROUGH THE CAROLINAS...WITH A SLACK GRADIENT AND LOW DEW POINTS OVER CENTRAL NORTH CAROLINA. THE HIGH WILL CONTINUE TO DRIFT SLOWLY EAST OVERNIGHT...AS THE UPPER RIDGE AXIS SHIFTS EAST AS WELL. CIRRUS AND A FEW AC WERE SPILLING OVER THE RIDGE INTO CENTRAL NORTH CAROLINA AND THIS SHOULD CONTINUE OVERNIGHT...WITH THE RUC AND THE NAM UPPER-LEVEL MOISTURE FORECASTS SHOWING THE CIRRUS OVER EASTERN TENNESSEE HOLDING TOGETHER SOME AS IT MOVES EAST ACROSS THE STATE. EXPECT THE CIRRUS TO THIN AS IT MOVES PAST THE RIDGE AXIS SO...AT MOST...ANTICIPATE PARTLY CLOUDY CONDITIONS OR MOSTLY CLEAR SKIES BECOMING PARTLY CLOUDY OVERNIGHT. LATE TONIGHT AND BY DAYBREAK TUESDAY...THE NAM AND THE GFS SHOW A SURGE OF MOIST AIR OFF THE ATLANTIC AND THE GULF DRIFTING NORTH UP THE SAVANNAH BASIN AND INTO WESTERN NORTH CAROLINA. THE LAYER OF MOISTURE IS ABOUT 100 MB DEEP AND BECOMES SATURATED BENEATH THE SUBSIDENCE INVERSION MAINTAINED BY THE SHARP RIDGE ALOFT. THERE IS SOME CONCERN THAT THE MODELS MAY BE OVERDOING THE EASTWARD TRANSPORT OF THIS MOISTURE FOLLOWING DIURNAL MIXING...AND THOUGH IR IMAGES DO SHOW DEVELOPMENT OF LOW CLOUDS TAKING PLACE IN SOUTHWEST GEORGIA AS FORECAST BY THE LOW-LEVEL MOISTURE FIELDS OF THE RUC AND THE NAM...THE LATEST GFS MOS IS DELAYED IN BRINGING LOWER LEVEL CLOUDS INTO THE WESTERN PIEDMONT UNTIL TUESDAY NIGHT. STILL...EXPECT SOME INCREASE IN STRATOCUMULUS ESPECIALLY WESTERN ZONES WITH MID AND HIGH CLOUDS RESULTING IN THE ENTIRE AREA BEING PARTLY TO MOSTLY CLOUDY IN THE AFTERNOON. INCREASED GRIDDED AND WORDED SOUTHERLY FORECAST WINDS IN THE WEST SLIGHTLY DURING THE AFTERNOON ANTICIPATING A LITTLE MORE MIXING...IN LINE WITH THE GRADUALLY INCREASING GRADIENT ON THE WEST SIDE OF THE HIGH AND A SLIGHT UPWARD TREND IN MOS GUIDANCE WINDS FOR TUESDAY AFTERNOON. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...SOUTH WINDS ON THE INCREASE TUESDAY NIGHT AHEAD OF APPROACHING FRONT. LOW LEVEL THICKNESS AND LOW CLOUDS ON THE INCREASE AS WELL. THUS OVERNIGHT LOWS SHOULD OCCUR BEFORE MIDNIGHT AND TEMPERATURES SLOWLY RISE TO MID 50S TO NEAR 60 BY SUNRISE WEDNESDAY. STILL MINOR TIMING DIFFERENCES IN ONSET OF PRECIPITATION WEDNESDAY BUT LIKELY NOTHING SIGNIFICANT NOR WIDESPREAD BEFORE MID AFTERNOON. ALL RAIN SHOULD EXIT MOST OF CENTRAL NORTH CAROLINA BEFORE MIDNIGHT WEDNESDAY NIGHT. STORM RELATIVE HELICITY FORECAST ABOVE 500 WITH WINDS IN EXCESS OF 50 KNOTS BELOW 5000 FEET DURING THE EVENT. FORECAST SOUNDINGS ARE A BIT MORE STABLE WITH THIS SYSTEM THEN ON MARCH FIFTEENTH. ALTHOUGH THE SEVERE THREAT IS NOT ZERO...IT DOES APPEAR LESSENED COMPARED TO THE PREVIOUS EVENT. FORECAST RAINFALL AMOUNTS OF FOUR TO SIX TENTHS OF AN INCH COULD BE SLIGHTLY ON THE LOW SIDE. SOME LOCAL AMOUNTS WILL EXCEED ONE INCH IN THE STRONGER THUNDERSTORMS. WITH PRECIPITATION A BIT DELAYED FROM THINKING OF SUNDAY...AFTERNOON HIGHS SHOULD BE LOW 70S WEST TO UPPER 70S EAST. WEDNESDAY NIGHT LOWS IN THE 40S. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 3 PM MONDAY...A BACK DOOR COLD FRONT HINTED AT ON SOME MODELS YESTERDAY FOR THE COMING WEEKEND LOOKS MORE CERTAIN AT THIS TIME. FRONT SLIPS SOUTH DURING THE DAY SATURDAY AND NORTHEAST FLOW IS EXPECTED TO PERSIST INTO SUNDAY NIGHT. IF LOW STRATUS ADVECTS INTO THE STATE SUNDAY NIGHT AS THE GFS MODEL SUGGESTS TEMPERATURES COULD STRUGGLE TO RISE MUCH PAST 50 DEGREES...AND DRIZZLE POSSIBLE AS WELL. WILL STAY A LITTLE ON THE OPTIMISTIC SIDE AT THIS TIME AND ADDRESS THIS IN THE FUTURE. WINDS SHIFT TO NORTHWEST TO WEST MONDAY BUT ENOUGH BOUNDARY LAYER MOISTURE REMAINS TO DEVELOP AFTERNOON CUMULUS MONDAY AND PERHAPS BECOME MOSTLY CLOUDY. AFTERNOON HIGHS IN THE 60S EXCEPT 50S OR LOWER SUNDAY AND MONDAY. MORNING LOWS GENERALLY WITHIN A FEW DEGREES OF 40. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... AS OF 750 PM MONDAY...SFC HIGH PRESSURE OVER NEW ENGLAND WILL CONTINUE TO RIDGE INTO CENTRAL NORTH CAROLINA TONIGHT...WITH THE RIDGE AXIS GRADUALLY SHIFTING EAST OVERNIGHT. DRY LOW LEVELS ALONG WITH A WEAK PRESSURE GRADIENT WILL SET THE STAGE FOR LIGHT WINDS AND MAINLY CLEAR SKIES TONIGHT...EXCEPT FOR SOME PASSING MID AND HIGH LEVEL CLOUDS. AS THE HIGH SHIFTS FURTHER OFFSHORE TOMORROW...MOISTURE WILL BEGIN TO INCREASE FROM THE SOUTH UNDER RETURN FLOW. GUIDANCE HAS BACKED OFF ON THE DEGREE OF ISENTROPIC LIFT AND RESULTANT LOW CLOUDS TOMORROW. THE LATEST FORECAST REFLECTS A LATER ARRIVAL OF STRATOCUMULUS...WITH ANY CIGS EXPECTED TO STAY VFR AND OCCUR AROUND 18Z AT GSO/INT AND 20-23Z AT RDU/FAY/RWI. MVFR CIGS WILL BEGIN TO ENTER INT CLOSE TO 00Z AS STRONGER ISENTROPIC LIFT DEVELOPS. -JFB/BLS WITH THE APPROACH OF A WARM FRONT FROM THE SOUTH...MVFR CONDITIONS ARE LIKELY OVER CENTRAL NC TUE NIGHT AND POSSIBLY LOWERING TO IFR A FEW HOURS WED MORNING. CONDITIONS MIX TO VFR WEATHER AHEAD OF A COLD FRONT FROM THE WEST AND LOWER LEVEL WINDS STRENGTHEN TO 50 KTS WITHIN 3 THSD FT OF THE SURFACE LATE WED. THE COLD FRONT IS LIKELY TO BE ACCOMPANIED BY A LINE OF HEAVY SHOWERS OR TSTMS OVER CENTRAL NC WED EVENING. FOLLOWING THE COLD FRONT EARLY WED NIGHT...VFR CONDITIONS ARE LIKELY WITH DRY AIR FROM HIGH PRESSURE DRIFTING EAST FROM THE TENNESSEE VALLEY. HIGH PRESSURE DRIFTS SLOWLY EAST THE NEXT TWO DAYS AND OFF THE COAST AND SHOULD MAINTAIN VFR WEATHER THROUGH THE END OF THE WEEK. -RFG && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLS NEAR TERM...DJF SHORT TERM...RLH LONG TERM...RLH AVIATION...BLS/JFB/RFG nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE WILMINGTON NC 125 AM EDT MON MAR 17 2008 .UPDATE... AS OF 1159 PM SUNDAY...HAVE UPDATED THE MARINE TO INCLUDE A "SMALL CRAFT EXERCISE CAUTION" HEADLINE LATE TONIGHT FOR THE INCOMING NORTHERLY SURGE. THIS SURGE IS CAUSING NEAR GALE-FORCE WINDS NEAR THE NC/VA BORDER AND THE LATEST RUC MODEL ACTUALLY BRING 25 KT WINDS INTO OUR COASTAL WATERS TONIGHT. WILL TREND INTO THIS CHANGE...BRINGING SUSTAINED NORTHERLY WINDS UP TO 20 KNOTS AFTER 2-3 AM AND HOLDING THEM THERE UNTIL SHORTLY AFTER DAYBREAK MONDAY. NO OTHER CHANGES AT THIS TIME. TRA && .SYNOPSIS... HIGH PRESSURE WILL BUILD IN FROM THE NORTH THROUGH MONDAY...THEN SLIDE OFFSHORE LATE TUESDAY. SHOWERS AND THUNDERSTORMS SHOULD ACCOMPANY A COLD FRONT LATE WEDNESDAY. HIGH PRESSURE WILL BUILD IN FROM THE WEST THE LATTER HALF OF THE WEEK WITH NEAR NORMAL TEMPERATURES AND DRY WEATHER EXPECTED. && .NEAR TERM /UNTIL 6 AM MONDAY/... AS OF 9 PM SUNDAY...LATEST SAT IMAGERY AND TRENDS INDICATE CLEAR SKIES...WHICH WILL LIKELY REMAIN ACROSS THE AREA OVERNIGHT. SFC BASED INVERSION EARLY THIS EVENING HAS ALLOWED SFC WINDS TO DECOUPLE. AS A RESULT...EXCELLENT RAD COOLING CONDITIONS WILL START THE NIGHT. AFTER 2AM MONDAY...A SHALLOW CAA SURGE TO COMMENCE AND LAST INTO LATE MORNING MONDAY. IT IS BEST PROGGED USING THE 925 MB TEMPS. IN ADDITION...SFC RIDGE AXIS WILL NOSE SOUTHWARD ACROSS THE INLAND CAROLINAS. THIS WILL ALSO RESULT IN A TIGHTENING OF THE SFC PRESSURE GRADIENT. LOOK FOR SFC NORTH TO NORTHEAST WINDS TO INCREASE ENOUGH ACROSS THE ILM CWA OVERNIGHT TO PREVENT A FULL NIGHTS WORTH OF RAD COOLING. MODELS INDICATING ENUF MOISTURE IN THE MID LEVELS FOR FEW/SCT ALTOCU BY DAYBREAK...AND POSSIBLY LASTING INTO MIDDAY MONDAY. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 PM SUNDAY...MID AND UPPER LEVEL RIDGE AXIS STILL WEST OF THE CWA ON MONDAY. HIGH PRESSURE CENTERED TO THE NORTH WILL RESULT IN A NE COMPONENT TO THE WIND...AND THIS WILL ACT TO KEEP TEMPS ON THE COOL SIDE OF CLIMO THROUGH MONDAY NIGHT. BY TUESDAY...THE UPPER RIDGE AXIS SHIFTS OVERHEAD AND RETURN FLOW AT THE SURFACE WILL PROPEL TEMPS BACK TO NEAR SEASONABLE VALUES. ALSO...THE GFS IS HINTING AT THE POSSIBLE DEVELOPMENT OF A WEAK COASTAL TROUGH EARLY TUESDAY WHICH WOULD LIFT NORTH AS A WARM FRONT. AT THIS POINT IT LOOKS LIKE THE ONLY IMPLICATIONS WOULD BE A WIND SHIFT. SPEAKING OF WIND...THE PRESSURE GRADIENT WILL BEGIN TO TIGHTEN OVER THE EASTERN CAROLINAS LATE TUESDAY AND TUESDAY NIGHT AS STRONG LOW PRESSURE AND ASSOCIATED COLD FRONT MOVES ACROSS THE MISSISSIPPI RIVER VALLEY. && .LONG TERM/WEDNESDAY THROUGH SUNDAY/... AS OF 3PM SUNDAY...DYNAMIC COLD FRONT WILL BE BEARING DOWN ON THE AREA WEDNESDAY ALTHOUGH ITS EXACT TIMING IS STILL IN QUESTION REGARDING A LATE AFTERNOON OR WED NIGHT FROPA. SPC HAS ALREADY HIGHLIGHTED MOST OF THE SOUTHEAST AND MIDATLANTIC FOR THE POSSIBILITY OF SEVERE WEATHER ON ACCOUNT OF STRONG LOW LEVEL WIND FIELDS. THE SWRLY FLOW WILL BOOST AFTERNOON HIGHS INTO THE UPPER 70S. ZONAL FLOW OVER THE EASTERN HALF OF THE NATION WHILE A STORM SYSTEM AFFECTS THE ROCKIES OR PLAINS WILL BRING SEASONABLE TEMPS TO START WITH A SLOW UPWARD TREND AS THE WEEKENDED NEARS. POPS WILL BE BROUGHT TO SLIGHT CHANCE BY SUNDAY DUE TO THE APPROACH OF THIS WESTERN STORM SYSTEM. SLOWER SOLUTIONS WILL LIKELY END UP BEING FAVORED HOWEVER AS A CERTAIN DEGREE OF PHASING MAY OCCUR EARLY NEXT WEEK. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... A NORTH-NORTHEAST COOL SURGE IS PUSHING ACROSS NORTHEASTERN SOUTH CAROLINA AT THE PRESENT TIME. STRONG PRESSURE RISES...ON THE ORDER OF 8 MB IN JUST 6 HOURS...ARE BUILDING SOUTH INTO THE REGION. SURFACE WINDS OF 8-10 KT WILL INCREASE TO 12G20KT AFTER SUNRISE AS MIXING COMMENCES. THE GUSTINESS WILL SUBSIDE THIS AFTERNOON...AND WINDS SHOULD BECOME LIGHT AND VARIABLE AFTER SUNSET TONIGHT. CIRRUS AND PERHAPS SOME MID-LEVEL ALTOSTRATUS ARE POSSIBLE TODAY...BUT SHOULD FADE OFFSHORE LATE THIS AFTERNOON AS THE NEXT MID AND UPPER LEVEL RIDGE BUILDS EAST. THERE IS A CHANCE OF TEMPORARY IFR CONDITIONS DURING THUNDERSTORMS WEDNESDAY AFTERNOON AND EVENING...ALONG THE NEXT SIGNIFICANT COLD FRONT EXPECTED TO AFFECT THE AREA. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 9 PM SUNDAY...WEAKNESS IN THE SFC PRESSURE FIELD HAS CAUSED WIND SPEEDS TO TEMPORARILY FALL BELOW 15 KT. AFFECTS FROM THE INTENSIFYING LOW EAST NORTHEAST AND WELL OFFSHORE FROM THE EAST COAST OF THE U.S ARE NO MORE. IN ITS WAKE...SFC HIGH TO RIDGE SOUTH ACROSS THE AREA WATERS LATER TONIGHT AND MONDAY. A SHALLOW BUT SHORT-LIVED CAA SURGE...COMBINED WITH A TIGHTENED SFC PG...WILL PUSH FROM NORTH TO SOUTH ACROSS THE AREA WATERS AFTER MIDNIGHT. HAVE INDICATED A SLIGHT VEERING IN THE WINDS TO NORTHEAST...WITH SPEEDS INCREASING TO 15-20 KT. SHORT PERIOD WIND DRIVEN WAVES WILL COMPRISE THE SEAS AND WILL INCREASE TO 4 TO 5 FT...EXCEPT AROUND 3 FT NEAR SHORE. WILL HAVE TO MONITOR FOR POSSIBLY ISSUING A SHORT TERM SMALL CRAFT EXERCISE CAUTION HAZARD. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 PM SUNDAY...HIGH PRESSURE LOCATED NORTH OF THE AREA WILL MOVE EAST...AND WINDS WILL SHIFT FROM NNE EARLY IN THE DAY TO ENE DURING THE AFTERNOON. THE POSSIBLE DEVELOPMENT OF A WEAK COASTAL TROUGH MONDAY NIGHT WOULD MAINTAIN AN EASTERLY COMPONENT TO THE WIND UNTIL EARLY TUESDAY MORNING. THIS TROUGH WOULD MOVE QUICKLY INLAND...AND WINDS WILL SHIFT TO THE SOUTH BY TUESDAY EVENING. AS STRONG LOW PRESSURE MOVES ACROSS THE MISSISSIPPI RIVER VALLEY...AN INCREASING PRESSURE GRADIENT OVER THE WATERS WILL CAUSE WIND SPEEDS TO INCREASE TO 20-25 KT BY TUESDAY NIGHT. SEAS ARE EXPECTED TO BUILD TO 5-6 FT AND PUSH INTO THE NEARSHORE WATERS AFTER MIDNIGHT. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 3PM SUNDAY...SMALL CRAFT ADVISORY LIKELY TO START THE PD AHEAD OF A DYNAMIC COLD FRONT. TOO EARLY TO TELL WHETHER OR NOT LOW LEVEL WIND FIELDS WILL SUPPORT ANY GALE GUSTS AND HOW SSTS WILL AFFECT MIXING. A SHARP VEER TO OFFSHORE WILL OCCUR WED NIGHT BEHIND THE FRONT. OFFSHORE WIND DIRECTION WILL BEGIN TO PUSH THE HIGHEST SEAS OUT OF THE FCST AREA ON THURSDAY BUT AS THE GRADIENT IS SLOW TO DECREASE SCEC HEADLINES MAY BE REQUIRED. WINDS MAY VEER SLIGHTLY TOWARDS THE END OF THE PD AHEAD OF AN APPROACHING BACKDOOR COLD FRONT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...BACON NEAR TERM...HOEHLER SHORT TERM...MORGAN LONG TERM...BACON AVIATION...TRA nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAND FORKS ND 846 PM CDT MON MAR 17 2008 .DISCUSSION...RADAR IMAGERY SHOWING RETURNS ACROSS CENTRAL ND ASSOCIATED WITH SFC TROUGH (WARM AIR ADVECTION) FROM NORTHERN STREAM SHORTWAVE. APPEARS COVERAGE IS ISOLATED. WILL KEEP 20 POPS CONSIDERING CURRENT ISOLD NATURE OF THESE SHOWERS...BUT WILL SPEED UP TIMING IN THE GRIDS. P-TYPE WITH THIS SFC TROUGH TRICKY FOR THE W FA...00Z RUC13 SHOWING 925MB-850MB REMAINING ABOVE FREEZING. SFC TEMPS WILL BE NEAR FREEZING...SO WILL HAVE TO WATCH CLOSELY FOR FZRA. FOR NOW WILL CHANGE DVL BASIN TO RAIN AND SNOW (NO FZRA). THINK PROBABILITY OF FZRA TOO LOW TO MENTION AT THIS TIME. WILL MAINTAIN P-TYPE AS ALL SNOW ACROSS THE REMAINDER OF THE FA WITH 00Z RUC13 SHOWING THERMAL PROFILE BELOW FREEZING. CLOUD COVER AND SOUTHERLY FLOW THROUGH MUCH OF THE NIGHT WILL NOT ALLOW MUCH TEMPERATURE FALL. SNOW COVERAGE FROM SOUTHERN STREAM WAVE REMAINING SOUTH OF THE FA FOR NOW...WILL MAINTAIN CHANCE POPS WITH THE SNOW SO CLOSE. && .AVIATION...KFAR/KGFK WILL CONTINUE TO REMAIN UNDER A STRATUS DECK...IFR WITH CIGS AROUND 600FT. -SN WILL CONTINUE UNDER MVFR/IFR CIGS IN BJI AS LIFT SLOWLY MOVES TO THE NE. EXPECT SNOW TO TAPPER OFF TONIGHT BUT MVFR TO IFR CONDITIONS WILL PERSIST. CIGS WILL SLOWLY LIFT TOMORROW MORNING AS WINDS SHIFT FROM THE S TO THE NW WITH TROUGH PASSAGE. && .PREV DISCUSSION... /ISSUED 258 PM CDT MON MAR 17 2008/ SHORT TERM... ALL MODELS HAVE NOW COME INTO BETTER AGREEMENT IN STRONGLY DOWNPLAYING WHAT WAS ONCE A POTENTIAL HEAVY SNOW THREAT FOR PARTS OF SE SD INTO CNTRL MN TONIGHT. LOOKING AT RADAR AND UPPER AIR JET STRUCTURE WOULD APPEAR BEST BET FOR PCPN WAS ACTUALLY EARLIER TODAY WITH ACTUALLY NOT A LOT OF SUPPORT TONIGHT FOR MUCH -SN. THIS IS CONFIRMED BY RADAR WITH SHOWS NO ECHOES AT ALL IN SD/NEB. OBS/RADAR STILL INDICATE SOME NUISANCE LIGHT SNOW IN WCNTRL MN (BJ-DTL-FFM EAST) AND THIS WILL LINGER A BIT INTO THE EVENING BEFORE MOVING OUT...AND THEN QUESTION IF ANY MORE WILL DEVELOP LATER TONIGHT. ONE CAVEAT IS AN AREA OF MID LEVEL FRONTOGENESIS STILL PROGGED FROM MARSHALL MN TO SOUTH OF DLH AND GFS DOES STILL WANT TO GENERATE PCPN WITH THIS BAND. GOING WITH THIS IDEA WILL LINGER SOME POPS IN THE FAR SOUTHEASTERN FCST AREA THRU THE NIGHT BUT DROP ANY MEASURABLE SNOWFALL TO UNDER AN INCH IN THAT AREA. OTHERWISE...ANOTHER FAST MOVING 500 MB VORT WILL MOVE THRU ERN ND LATE TONIGHT AND INTO MN TUESDAY. GFS STANDS ALONE IN GENERATING SOME LIGHT QPF WHILE OTHER MODELS DRY. GIVEN SOME WEAK ECHOES IN ERN MT AND IN SASK WITH THE SYSTEM WILL MAINTAIN 20 POP OVERNIGHT INTO EARLY TUESDAY FOR THIS SYSTEM. TEMPS TONIGHT WILL BE MILD AS DEW PTS REMAIN FAIRLY HIGH. SKY COVER A BIT OF A TROUBLE...AS CLEAR WEDGE REMAINS DVL-JMS-BIS AREA AND THIS WILL LIKELY HOLD TIL MID CLDS ADVANCE EAST FROM WRN ND THIS EVE. LOWER CLOUDS WILL LIKELY HOLD TOO ROX-GFK-ABR EASTWARD IN DEEPER 850 MB MOISTURE STILL PROGGED TO HANG AROUND TONIGHT. EXPECT SOME MORNING CLOUDS AND PSBLY A LITTLE -SN TUES MORNING...THEN SOME CLEARING AS 500 MB VORT MOVES EAST. 850 MB TEMPS ARE JUST A TOUCH COOLERE THAN TODAY...BUT WITH SOME SUN AND INCREASING BARE GROUND IN SPOTS IN PARTS OF ERN ND THINK ITS TIME TO ADJUST TEMPS UP SOME IN ND. DID GO ALONG WITH GFS WITH NEXT 500 MB VORT DIVING SOUTHEAST ON WEDNESDAY. 12Z NAM LOOKED WAY OVERDONE. DO EXPECT A NARROW AREA OF SOME PCPN RIGHT ALONG VORT TRACK FROM WRN ND INTO ERN SD WITH CHANCE OF R/S BRUSHING FAR SOUTHWEST FCST AREA. ADDED 20 POP FOR THIS FOR WED AFTN. LONG TERM (FRI-MON)... MODELS IN FAIRLY GOOD AGREEMENT AT THE BEGINNING OF THE PERIOD AND THEN BEGIN TO DIVERGE IN THEIR SOLN NEXT WEEKEND. 500MB FLOW LOOKS TO CONTINUE ITS ACTIVE MARCH PATTERN IN THE EXTENDED TIME FRAME. FRIDAY AM...SFC HIGH PRESSURE SITUATED OVER THE WESTERN GREAT LAKES WILL PROVIDE CLIMATOLOGICALLY DRY AIR WITH SOUTHEASTERLY FLOW INTO THE NEXT WAVE PROLONGING THE START OF PCPN. THUS DELAYED THE 20 POP TO JUST THE WESTERN FRINGE OF THE FA ON FRI. TWEAKED THE POPS ON SAT TO THE SOUTHERN HALF OF THE AREA...IT APPEARS THAT THE HIGH WILL KEEP THINGS DRY ACROSS THE NORTH. WENT WITH HPC GUIDANCE FOR THE SAT AND SUN TIME FRAME...CONFIDENCE IS LOW WITH THE TIMING AND TRACK OF THE NEXT WAVE. TEMPERATURES WILL CONTINUE TO BE NEAR SEASONAL AVERAGES. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 156 PM EDT TUE MAR 18 2008 .SYNOPSIS... RAIN WILL SPREAD EAST ALONG DEVELOPING WARM FRONT...ACROSS OH AND NORTHERN WV. WARM FRONT MOVES NORTH TONIGHT AS LOW PRESSURE ENTERS OHIO VALLEY. THAT LOW PULLS A COLD FRONT THROUGH LATE WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... RAIN IS MAKING PROGRESS FURTHER SOUTH AND EAST...AS A WARM FRONT DEVELOPS JUST SOUTH OF HTS/CRW/BKW AND THEN EXTENDED WEST TOWARD LEX/SDF. RAIN CONTINUES TO FORM ALONG AND NORTH OF THIS BOUNDARY AND THEN HEADS EAST INTO OHIO AND NRN WV. SO HAVE INCREASED POPS FURTHER SOUTH AND EAST...BUT HAVE HELD TO THE DRY WEATHER SOUTH AND EAST OF CRW. BUT WILL HAVE TO WATCH THIS CLOSELY AS THE NEW 12Z NAM SHOWS THAT THIS INITIAL SHOT OF PRECIPITATION MAKES IT THROUGH CRW AND MAYBE AS FAR SOUTH AS BKW. ALSO SEEING THAT THE CLOUDS WILL HOLD IN PLACE FOR MOST AREAS SO HAVE INCREASED THE SKY COVER AS WELL AS LOWERING THE HIGHS ABOUT 5 DEGREES ACROSS THE BOARD AND THAT MAY NOT BE NEAR ENOUGH FOR SOME OF THE NRN LOCATIONS ALONG THE US 50 CORRIDOR AND FURTHER NORTH. BY THIS EVENING...THIS INITIAL BAND OF RAIN SHOULD FINALLY LIFT NORTH OF THE REGION BY 6Z AS THE MAIN UPPER LEVEL TROUGH AND SIGNIFICANT SURFACE LOW ENTER THE OHIO VALLEY. HAVE LOWERS POPS SOME FOR TONIGHT...BUT WITH NEW GUIDANCE ARRIVING WILL BE TWEAKING FURTHER TO SHOW THE DRIER PERIOD TONIGHT. AS FAR AS THE FLOOD WATCH GOES...HAVE EXPANDED THE AREA BY 7 COUNTIES TO BEGIN TO MOVE THE AXIS OF RAIN INTO NWRN WV AS WELL. STILL COULD SEE 1 TO 2 INCHES OF RAIN WITH THIS SYSTEM ACROSS SE OH INTO NRN WV AS THE RAIN TRAINS ALONG THE WEAK WARM FRONT. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... COMPLEX SYSTEM MOVES THROUGH WED AND WED NT. SOUTHERN STREAM UPPER LEVEL LOW OPENS UP INTO A SHORT WAVE TROUGH AS IT LIFTS NE ON THE E SIDE OF THE LONG WAVE TROUGH POSITION. THIS IS GOOD NEWS AS THE SYSTEM PICKS UP SPEED...ENOUGH SO THAT PORTION OF THE CWA SE OF THE OH RIVER WILL NOT HAVE THE EXCESSIVE RAIN THAT WILL TAKE PLACE IN OH OVER THE NEXT THREE PERIODS. INDEED...FRONTOGENESIS IS SHOWN TO BE WEAK AS THE SYSTEM OPENS UP BUT GOOD UPPER DIV...MID LEVEL CONV OF Q AND DEFM STILL EXIST SUFFICIENTLY TO WARRANT CAT POPS FOR WED. SLOWED ONSET OF PRECIPITATION BY ABOUT 3 HRS BASED ON LATEST MODEL DATA BUT KEPT THE END TIME ABOUT THE SAME. ROLLED WITH HPC QPF WHICH WAS CLOSE TO THE NAM. THE NAM12 HAD WHAT WAS LIKELY TOO MUCH DETAIL FOR THIS PROJECTION IN TIME AS ASSOCIATED DYNAMICS ARE LIKELY TO CHANGE SOMEWHAT. EVENT TOTAL PRECIPITATION DROPS OFF SHARPLY ACROSS THE OHIO RIVER ON ACCOUNT OF THE INCREASED SPEED OF THE SYSTEM. STRONG WINDS AHEAD OF THE SYSTEM COUPLED WITH SMALL AMOUNT OF CAPE NECESSITATES THE MENTION OF THUNDER IN THE FORECAST. THE TIMING OF THE FRONT IS FAVORABLE FOR CONVECTION OVER THE EASTERN ROUGHLY HALF OF THE AREA BUT THE AMOUNT OF CLOUDS AND PRECIPITATION ASSOCIATED WITH THIS SYSTEM WILL LIKELY LIMIT DAYTIME HEATING SOMEWHAT. SPC HAS ISSUED A SLIGHT RISK FOR EXTREME SE PORTIONS OF AREA...THE MOST LIKELY TO HAVE SOME OPPORTUNITY FOR HEATING...AND WILL HIGHLIGHT THUSLY IN HWO. SFC WAVE LIFTS N OF THE AREA WED EVE AS OPEN SHORT WAVE LIFTS OUT. THIS WILL TAKE THE PRECIPITATION WITH IT AND BRING COLDER AIR IN ITS WAKE. THE COLD ER AIR WILL BE ENOUGH FOR A TRANSITION TO SNOW SHOWERS IN THE MOUNTAINS VERY LATE WED NT. STRONGEST WIND GUSTS WITH SYSTEM...NOTWITHSTANDING CONVECTION...WILL LIKELY BE TRANSFERRED DOWN AS THE COLD FRONT COMES THROUGH WED EVE, PEAK GUSTS OFF THE RUC ALGORITHM USING THE NAM ARE JUST BELOW CRITERIA FOR WIND ADVISORY ACROSS HIGHER TERRAIN SO ONE IS NOT NEEDED DUE TO THE SMALL SCALED NATURE THE EVENT. A NUMBER OF FAST MOVING CLIPPERS STREAK THROUGH IN THE FAST WNW FLOW ALOFT. MODELS SHOW A SMALL HINT OF ONE AS EARLY AS THU NT. A MORE ORGANIZED CLIPPER APPROACHES NEAR THE END OF THE PERIOD...A LITTLE SLOWER THAN PREVIOUS RUNS. ROLLED WITH THE MET FOR HIGHS WED...MOST NOTABLE DIFFERENCE BEING LOWER IN THE W WITH THE ONSET OF PRECIPITATION AND EVENTUAL FRONTAL PASSAGE THERE. TOOK NUMBERS UP TO THE LOWER MET FOR LOWS WED NT WHILE MAKING LITTLE CHANGE TO HIGHS THU. RAISED LOWS A BIT S THU NT WHILE LITTLE CHANGE WAS NEEDED TO HIGHS FRI OR LOWS FRI NT. && .LONG TERM /SATURDAY THROUGH MONDAY/... A FAST MOVING SHORT WAVE MOVES FROM THE CENTRAL PLAINS EAST THROUGH THE AREA ON SATURDAY. HPC GUIDANCE SUGGEST THE LOW TRACK RIGHT ACROSS WV...POSING A POSSIBILITY OF MIXED PRECIP ACROSS THE EXTREME NORTH. GFS AND ECMWF IN AGREEMENT BRINGING QPF ACROSS THE NORTHERN SECTIONS OF WV BY SAT 06-12Z...SPREADING SLOWLY SOUTH TO THE REST OF THE AREA THRU SUN 00Z. BOTH MODELS SHOW H8 FREEZING LINE JUST NORTH OF THE CWA AT 12Z SAT...WITH NORTHERLY FLOW PUSHING COLDER AIR AND FREEZING LINE SOUTH OF THE CWA BY SUN 12Z. THEREFORE...MIXED PRECIP OR SNOW SHOWERS WILL START ACROSS THE NORTHERN SECTIONS...WHILE RAIN SHOWERS WILL PREVAIL ACROSS THE SOUTHERN TWO THIRDS EARLY SATURDAY. ABOVE FREEZING TEMPS WILL PREVAIL AT THE LOWER LEVELS SATURDAY...CAUSING PRECIP TO PREVAIL AS LIQUID ACROSS THE ENTIRE AREA BY SAT AFTERNOON. PERHAPS THE NORTHEAST MOUNTAINS COULD SEE MIXED PRECIP SAT AFTERNOON AND ALL SNOW SAT EVENING. ANOTHER WEAK LOW PRESSURE MOVES INTO THE OH VALLEY ...PROVIDING A SMALL CHANCE OF PRECIP ON EASTER SUNDAY. HOWEVER...MODELS SOLUTIONS SPREAD FROM DAY 6-7...SO THERE IS LOW CONFIDENCE WITH THIS SYSTEM AND CHANGES IN FORECAST COULD OCCUR DURING THE NEXT COUPLE OF DAYS. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... WARM FRONT THAT STRETCHES FROM THE SRN COAL FIELDS OF WEST VIRGINIA TO NEAR SDF CONTINUES TO BE THE DIVIDE BETWEEN RAIN AND DRY WEATHER. THIS FRONT GRADUALLY LIFT NORTH DURING THE AFTERNOON AND MOVE INTO PA AND NRN OHIO BETWEEN 00Z AND 6Z TONIGHT. IN THE BAND OF RAIN NOT SEEING CEILING DIP MUCH BELOW 3500 FT...MOST STILL SHOWING 4000 TO 5000 FT CEILINGS...BUT VISIBILITIES DROPPING DOWN TO BETWEEN 2 AND 4 MILES IN THE STEADY RAIN FOR PKB/CKB. EKN SHOULD GET CLIPPED THIS AFTERNOON SO SOME VISIBILITY RESTRICTIONS CAN BE EXPECTED THROUGH ABOUT 00Z WED. THE BAND OF RAIN WILL SHIFT NORTH WITH THE FRONT THIS EVENING WITH VFR CONDITIONS RETURNING AREA WIDE OVERNIGHT. SOUTH OF THE BOUNDARY VFR CONDITIONS CURRENTLY IN PLACE AND SHOULD REMAIN. AFTER 12Z WED...STRONG LOW PRESSURE WILL MOVE ACROSS THE OHIO VALLEY WITH A STRONG COLD FRONT SWINGING THROUGH. EXPECT SHRA AND TSRA WITH THE FRONT BEGINNING A EARLY AS 15Z FOR PKB/HTS. IT SHOULD BE ENTERING THE MOUNTAINS AROUND 18Z. AVIATION OUTLOOK /AFTER 18Z WEDNESDAY/ IFR RA PSBL ALONG AND AHEAD OF COLD FRONT...WITH CONDITIONS IMPROVING BEHIND THE FRONT. && .HYDROLOGY... HOISTED FLOOD WATCH FOR PARTS OF SERN OH DUE TO THE THREAT OF EXCESSIVE RAINFALL. FOLLOWING THE NAM OUTPUT WHICH YIELDS ONE TO TWO INCHES OVER THE WATCH AREA. DEEP MSTR SURGES NORTHWARD...WHILE A BOUNDARY SETS UP THROUGH CENTRAL OHIO AND IND. IN ADDITION...WAVES OF LOW PRESSURE RIDE ALONG THE BAROCLINIC ZONE. EXPECT STRONG RISES ON STREAMS AND CREEKS TUESDAY NIGHT WITH RIVERS BECOMING SWOLLEN OR POSSIBLY GOING INTO FLOOD WED. WE WILL BE CLOSELY WATCHING THE MUSKINGUM AND HOCKING RIVERS...ESPECIALLY SINCE THEIR RESPECTIVE HEADWATERS GET NAILED WITH TWO TO THREE INCHES OF QPF. IT WILL TAKE INTO THE WEEKEND OR PERHAPS LONGER BEFORE SECTIONS OF THE MUSKINGUM FALL BELOW ACTION STAGE. AT THIS POINT...THE GROUND CAN WITHSTAND 1.5 - 2.0 INCHES WITH AMOUNTS GREATER CAUSING HIGH WATER. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR WVZ009>011-019-020. OH...FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR OHZ066-067-075-076- 083>086. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/29 NEAR TERM...ESS SHORT TERM...TRM LONG TERM...TRM/ARJ AVIATION...ESS HYDROLOGY... oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 656 AM EDT TUE MAR 18 2008 .SYNOPSIS... A WARM FRONT WILL LIFT NORTH ACROSS THE REGION TODAY...AND BE THE FOCUS FOR WIDESPREAD RAINFALL. HEAVY RAIN AND EMBEDDED THUNDERSTORMS WILL PERSIST FOR TONIGHT AND WEDNESDAY AS SEVERAL WAVES OF LOW PRESSURE RIDE ALONG A TRAILING COLD FRONT. HIGH PRESSURE WILL BUILD INTO THE OHIO VALLEY FOR THURSDAY WITH DRY WEATHER. && .NEAR TERM /THROUGH TONIGHT/... PCPN COVERAGE CONTINUES TO GRADUALLY EXPAND ACRS WESTERN FCST AREA ERLY THIS MRNG. WARM FRONT CURRENTLY EXTNDG NORTHEAST ALONG THE OHIO RIVER LIFTING SLOWLY NORTH. INCREASING LO LVL WAA PRODUCING LARGE AREA OF OVERRUNNING RAINFALL WITH EMBEDDED TSTMS NORTH OF THE WARM FRONT TO SOUTHWEST OF FCST AREA. TEMPS HAD RISEN INTO THE 40S ACRS THE FCST AREA. PROLONGED AND SIGNIFICANT RAINFALL EVENT COMMENCING ACRS REGION THIS MRNG. 06Z RUC HAS A REAL NICE HANDLE ON THE ONGOING PLACEMENT OF THE WARM FRONT AND THE STRENGTHENING LO LVL DYNAMICS INVOF THE BNDRY. 50-60KT 850 LLJ NOSING NE UP THE OHIO RIVER VLY...FUELING AXIS OF DEEP MOIST CONVERGENCE AS WARM FRONT SLOWLY LIFTS NORTH ACRS FCST AREA TODAY. AXIS OF ELEVATED INSTABILITY ALSO RIDING ALONG BNDRY AND WILL BE FOCUS FOR EMBEDDED TSTMS AS DEEPER GULF MOISTURE IS TRANSPORTED NORTH INTO THE OH VLY THRU THE MRNG HOURS. WHILE QPF HAS BEEN LIGHT (0.10 IN/HOUR OR LESS) UP TO THIS POINT...PCPN ACCUMS APPCHG 0.40-0.60 IN/HOUR CLOSER TO LEAD SFC WAVE ACRS SRN MISSOURI/ILLINOIS/SW INDIANA. EXPECT THESE HEAVIER RAINS WILL SHIFT NORTHEAST ALONG FRNTL BNDRY AND INTO WESTERN FCST AREA WITHIN NEXT FEW HOURS. AS WARM FRONT LIFTS NORTH...BELIEVE AXIS OF HEAVIEST RAINFALL WILL EXTEND FROM SE INDIANA NORTHEAST TO ENCOMPASS ALL THREE METRO AREAS. THIS ALIGNS VERY NICELY WITH PRECIP EFFICIENCY PROGS WHICH INDICATE AXIS OF DEEP CONVERGENCE TO 700MB ALONG NRN FLANK OF STRONG LO LVL JET COMBINED WITH PWATS APPCHG 1.5 INCHES INVOF FRNTL BNDRY. ACRS FAR SRN FCST AREA FROM GRANT CO NORTHEAST INTO LEWIS/SCIOTO COS...RAIN LKLY TO BE MORE SCATTERED THIS MRNG AND POSSIBLY INTO THE AFTN AS WELL...AS WARM FRONT FOCUSES FURTHER NORTH OF THIS AREA. HAVE PLACED A TIGHT POP GRADIENT IN THIS AREA...WITH MORE OF THE HEAVIER AND WIDESPREAD RAINFALL NOT LIKELY TO FOCUS ACRS NE KY/SO CNTRL OH UNTIL THIS EVNG AND OVERNIGHT. REGARDLESS...NOT GOING TO GET FANCY WITH FLOOD WATCH HEADLINES AND WILL CONTINUE TO LET THEM ROLL AT 12Z FOR ENTIRE FCST AREA ALONG AND SOUTH OF THE I-70 CORRIDOR. FLOOD WATCH ALREADY RUNNING NORTH OF I-70 (STARTED AT 06Z) AND THESE HEADLINES WILL CONTINUE AS WELL. WINDS HAVE THE POTENTIAL TO BE GUSTY SOUTH OF THE WARM FRONT...PARTICULARLY IN FAR SRN FCST AREA HIGHLIGHTED ABV WHERE LESS PCPN COVERAGE WILL ALLOW FOR MORE MIXING OF THE BNDRY LYR AND ENABLE SOME OF THE AFOREMENTIONED LO LVL JET TO BE PULLED DOWN TO THE GROUND. FRNTL BNDRY PULLS BACK TO NORTHWEST TONIGHT IN RESPONSE TO ANOTHER DEEPENING SFC WAVE LIFTING NORTHEAST INTO THE REGION. THIS WILL SHIFT HVY RAIN AXIS SLIGHTLY...TO FOCUS BACK TO THE WEST OF I-71 WHERE DEEPEST LO LVL CONVERGENCE AXIS ALIGNS WITH SLUG OF GULF MOISTURE. PERSISTENT LO LVL JET AT 60-70KTS ALIGNS JUST EAST OF THIS AREA ALL NIGHT. LARGE AREA OF UPR DIFFLUENCE SETS UP ACRS OH VLY OVERNIGHT TO RIGHT OF 140KT UPR JET ACRS WESTERN GRT LKS. THIS COMBINED WITH ADDL UPR JET ENERGY ROUNDING BASE OF APPCHG UPR LO LATE TONIGHT WILL PRODUCE EXCELLENT UPR LVL DYNAMICS ACRS REGION AND FURTHER ASSIST IN WIDESPREAD HVY RAINFALL. WILL CONTINUE WITH CAT POPS FOR MOST OF FCST AREA EXCEPT FAR SE COUNTIES. EMBEDDED TSTMS WILL CONTINUE AS WELL WITH AVAIL ELEVATED INSTABILITY... FURTHER ADDING TO ROBUST RAINFALL TOTALS. TEMPS...AS WARM FRONT LIFTS NORTH TODAY...WILL SEE TEMPS RISE INTO THE 50S ACRS NRN 1/2 FCST AREA...WITH POTENTIAL AT L/M60S ACRS THE SOUTH. LEANED IN GENERAL TOWARDS MET GUID FOR AFTN HIGHS. TEMPS WILL FALL BACK INTO THE 40S AND 50S TONIGHT...POSSIBLY EVEN THE U30S ACRS WEST CNTRL OH AS COOLER AIR IS PULLED SOUTH ON BACK SIDE OF FRNTL BNDRY. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... PROLONGED RAINFALL CONTINUES INTO WED AS AFOREMENTIONED SFC WAVE LIFTS THRU OH VLY...FOLLOWED BY YET ANOTHER DEEPENING WAVE DURING THE DAY AHEAD OF APPCHG UPR LO. MID/UPR LVL DYNAMICS REMAIN IDEAL FOR A CONTINUATION OF THE WIDESPREAD HVY RAINFALL WITH SECONDARY UPR JET AHEAD OF UPR LO LIFTING ACRS FCST AREA DURING THE AFTN. STRONG 60+KT 850 LLJ PERSISTS TO THE RIGHT OF DEEP CONVERGENCE AXIS...TRANSITIONING SLOWLY EAST ACRS FCST AREA THRU THE DAY AS FINAL SFC WAVE LIFTS NORTHEAST THRU REGION. EVEN AS HEAVIER AXIS OF PCPN SHIFTS EAST WITH THE FRONT INTO THE AFTN HOURS...MID LVL DEFORMATION AND FRONTOGENETICAL FORCING AXIS ON BACK SIDE OF UPR TROF WILL ENABLE RAIN TO PERSIST ALL DAY LONG. EMBEDDED TSTMS WILL REMAIN A POSSIBILITY ALONG AND AHEAD OF FRONT THRU ABOUT MID AFTN. AS COLDER AIR ADVECTS IN FROM NORTHWEST INTO THE EVNG HOURS... RAIN WILL LIKELY MIX WITH OR CHANGE OVER TO A BRIEF PERIOD OF WET SNOW BEFORE ENDING AFT MIDNIGHT. WHEN PCPN IS ALL SAID AND DONE LATE WED NIGHT...EXPECT A LARGE AREA OF 2 TO 4 INCHES OF RAINFALL ALONG AN AXIS EXTNDG FROM SE INDIANA NE THRU THE CVG/DAY/CMH METROS...WITH AROUND 2 INCHES ON EITHER SIDE OF THAT AXIS ACRS REMAINDER OF FCST AREA. WITHIN THE 2 TO 4 INCH AREA...SEEMS QUITE PLAUSIBLE THAT SOME LOCALIZED AREAS WILL APPCH 5 INCHES. CONSIDERING RECENT ACTIVE WX PATTERN HIGHLIGHTED BY ABV NORMAL PCPN COURTESY OF SVRL SIGNIFICANT STORMS AND A 12-18 INCH SNOWMELT...GROUND IS BEYOND SATURATED. MANY AREA STREAMS/RIVERS CONTINUE TO RUN NEAR BANKFUL AND THIS AMOUNT OF RAINFALL WILL LIKELY CAUSE SIGNIFICANT AND POTENTIALLY WIDESPREAD COUNTY/RIVER FLOODING. WEAK SFC HI PRES BUILDS INTO OH VLY THURS PROVIDING A BRIEF BREAK FROM PCPN. SHOULD SEE SOME SUNSHINE...WITH CLOUDS INCREASING LATE IN THE DAY AND INTO THURS NIGHT AHEAD OF ANOTHER APPCHG SFC LO. THIS TIME...SFC LO WILL APPCH RAPIDLY FROM THE NRN PLAINS. MODEL CONSENSUS INDCG WARM FRONT WILL SET UP ACRS NRN FCST AREA LATE THURS NIGHT AND COMBINATION OF INCREASING ISENT LIFT AND LO LVL WAA WILL ENABLE PCPN TO DVLP PRIOR TO DAYBREAK IN WEST CNTRL OH. AT THIS TIME...TEMPS APPEAR COLD ENUF INITIALLY FOR PCPN TO BEGIN AS SNOW. MORE ON THIS SYSTEM AND ITS IMPACTS FOR FCST AREA IN LONG TERM DISCUSSION. TEMPS...FAIRLY SHARP TEMP GRADIENT ON WED AS FRNTL BNDRY BISECTS FCST AREA. MOST LOCATIONS WILL SEE HIGH TEMPS FOR THE DAY REACHED IN THE MRNG...AS LO LVL CAA DVLPS ON BACK SIDE OF FRNTL BNDRY. LEANED TOWARDS WARMER MAV GUID FOR HIGHS. ALSO TRENDED TOWARDS MAV GUID THRU REMAINDER OF FCST PERIOD...AS TEMPS RETURN TO SLIGHTLY BELOW NORM LVLS. && .LONG TERM /FRIDAY THROUGH MONDAY/... MODELS HAVE BEEN CONSISTENT ON BRINGING A FAST MOVING BUT POTENT WX SYSTEM ACROSS THE OHIO VALLEY REGION FRIDAY/FRIDAY NIGHT. LOW PRESSURE IS FORECAST TO TRACK ALONG THE OHIO RIVER VALLEY FRIDAY NIGHT. AS THE LOW APPROACHES THE REGION FROM THE WEST ON FRIDAY...A WARM FRONT WILL PIVOT NORTH INTO THE REGION...AND WILL ESSENTIALLY BISECT THE FORECAST AREA. THIS SYSTEM HAS A RESEMBLANCE OF BEING A CLIPPER IN WHICH MOST OF THE PCPN FALLS NORTH OF THE WARM FRONT. WILL CONFINE POPS TO THE NRN HALF OF THE CWFA ON FRIDAY. PCPN WILL FALL AS MAINLY RAIN...WITH A MIXTURE OF RAIN/SNOW ACRS THE FAR NORTH. SINCE THE WARM FRONT WILL BISECT THE AREA...THERE WILL BE A SHARP TEMPERATURE GRADIENT FOR HIGHS. HIGHS WILL RANGE FROM NEAR 40 FAR NORTH TO THE UPPER 50S SOUTH OF THE OHIO RIVER. AS THE LOW TRAVERSES ALONG THE OHIO RIVER FRIDAY NIGHT...STRONG...MOIST ASCENT IN CONJUNCTION WITH DECENT LOW TO MID LVL FRONTOGENETIC FORCING WILL SPREAD PCPN ACRS THE ENTIRE REGION. HAVE BUMPED POPS INTO THE 40 TO 50 PERCENT RANGE. IF MODELS CONTINUE TO TREND THE SAME AS THEY HAVE FOR SEVERAL RUNS NOW...POPS WILL EVENTUALLY HAVE TO BE RAISED EVEN HIGHER. AS COLDER AIR FILTERS IN FROM THE NORTH...PCPN WILL CHANGE OVER TO SNOW FROM NW TO SE OVERNIGHT. THERE COULD BE AT LEAST A COUPLE OF INCHES OF WET SNOW WITH THIS SYSTEM...ESPECIALLY ALONG AND NORTH OF I-70. WILL CONTINUE TO MONITOR THIS SYSTEM AS THE WEEK GOES ALONG. THE LOW WILL MOVE AWAY FROM THE REGION BY SATURDAY MORNING. ANY LINGERING SNOW WILL END QUICKLY AND SKIES WILL BECOME PARTLY CLOUDY. HIGHS SATURDAY WILL RANGE FROM THE LOWER 40S NORTH TO THE UPPER 40S SOUTH. FOR THE REMAINDER OF THE EXTENDED...SATURDAY NIGHT THROUGH MONDAY...HAVE KEPT FORECAST AS IS FROM PREVIOUS SHIFT. MODELS CONTINUE TO STRUGGLE WITH UPCOMING DIGGING ENERGY IN NWLY FLOW ALOFT...GIVING MIXED SIGNALS AS TO WHETHER OR NOT A STORM SYSTEM WILL AFFECT THE OHIO VALLEY REGION ON SUNDAY INTO MONDAY. WILL HOPE FOR BETTER MODEL CONSENSUS WITH FUTURE RUNS. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... CIGS AND VSBYS WILL DETERIORATE THROUGH THE TAF PERIOD AS FRONTAL SYSTEMS ACROSS THE REGION INTERACT WITH COPIOUS AMOUNTS OF GULF MOISTURE. A WARM FRONT ALONG AND SOUTH OF THE LOWER OHIO RIVER VALLEY THIS MORNING WILL LIFT NORTHEAST THROUGH THE TAF SITES BETWEEN 16Z AND 20Z. INCREASING UPPER LEVEL LIFT AND LOW LEVEL FORCING WILL RESULT IN WIDESPREAD RAIN ACROSS THE FORECAST AREA. MODELS CONTINUE TO INDICATE ELEVATED INSTABILITY WITH THE APPROACHING WARM FRONT THROUGH THE MORNING AND EARLY AFTERNOON HOURS. THUS...SOME EMBEDDED THUNDERSTORMS WILL BE POSSIBLE WITHIN THE RAIN. BEST CHANCE WILL BE NEAR KCVG AND KLUK AND WILL INCLUDE TEMPO TSRA AT THESE LOCATIONS THROUGH AT LEAST 16Z. WILL EMPLOY THE CB DESCRIPTOR AT KDAY AND KILN WHERE THUNDERSTORM THREAT IS MUCH SMALLER. ATTM...AM NOT EXPECTING THUNDERSTORMS AT THE KCMH AND KLCK TERMINALS...ALTHOUGH AN ISOLATED THUNDERSTORM CAN NOT BE RULED OUT. FOR THE TAF PERIOD 20Z THROUGH 12Z...A COLD FRONTAL BOUNDARY WILL SAG SLOWLY SOUTHEAST INTO THE FORECAST AREA. WAVES OF LOW PRESSURE ARE EXPECTED TO RIDE ALONG THIS BOUNDARY THROUGH 12Z AND BEYOND. THESE SURFACE LOWS...ALONG WITH STRONG UPPER LEVEL LIFT AND LOW LEVEL JET FORCING...WILL ONLY ACT TO ENHANCE THE RAINFALL ACROSS THE OHIO VALLEY REGION. THUS...HAVE INCLUDED MODERATE TO HEAVY RAIN IN THE TAFS...WHICH WILL PRODUCE IFR CIGS AND VSBYS. OUTLOOK...IFR CIGS AND VSBYS LIKELY THROUGH WEDNESDAY AFTERNOON. MVFR CIGS AND VSBYS LIKELY WEDNESDAY EVENING. MVFR CIGS AND VSBYS POSSIBLE FRIDAY AFTERNOON THROUGH SATURDAY MORNING. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR OHZ026-034-035- 042>046-051>056-060>062. FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR OHZ063>065-070>074- 077>082-088. KY...FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR KYZ089>100. IN...FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR INZ050-058-059. FLOOD WATCH THROUGH WEDNESDAY AFTERNOON FOR INZ066-073>075-080. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM...HICKMAN AVIATION...HICKMAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 627 AM EDT TUE MAR 18 2008 .SYNOPSIS... ONE LAST WARM AND DRY DAY FOR A GOOD CHUNK OF THE AREA UNTIL LOW PRESSURE APPROACHES TONIGHT. THAT LOW PULLS A COLD FRONT THROUGH WEDNESDAY AFTERNOON AND EVENING. WEAKER SYSTEMS FOLLOW THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... QUIET AND MILD PREDAWN WITH A CANOPY OF MID DECK OBSCURING FULL WORM MOON. SE WINDS HAVE KEPT TEMPS NEARLY STEADY AND PLACES THAT RADIATED LAST EVNG ARE RISING DUE TO NOCTURNAL INV BEING BROKEN. MOS TEMPS ARE OFF BY TEN DEGREES AS OF 6Z AT MOST LOCATIONS. NEAR TERM IS THE CALM BEFORE THE STORM. COMBINATION OF A KATABATIC WIND AND MID LVL HGT RISES SUPPORT A PRECIP FREE FCST OUTSIDE NWRN AREAS. USED NAM/ECMWF SLTN WHICH IS SLOWER EXITING SERN RDG...THEREFORE KEEPING ERN 2/3 OF CWA DRY AND WARM. CONFINED LKLY/CAT POPS FM JACKSON COUNTY OHIO THRU TYLER COUNTY WITH SCHC TO CKB. WEAK 305-315K ISENTROPIC UPGLIDE COULD YIELD RW-- MUCH LIKE MONDAY...BUT DID NOT INCLUDE THAT INTO THE FCST GIVEN 10-20F T/TD SPREAD XPCTD THIS AFTN. DUE TO POOR VERIFICATION OF GUID AT THIS HOUR...CONTD TO BE A FEW DEGREES ABOVE MET SAVE FOR BKW. SE WINDS WILL KEEP ERN SLOPES IN THE 50S. ADIABATIC MIXING ALLOWS WINDS GUST BTWN 25 TO 35 MPH THIS AFTN. PCPN SHUNTS WWRD THIS EVNG AS WE AWAIT NEXT LOW RIDING UP THE MS RVR VLY. PUSHED CHC POPS ALL THE WAY TO INTERIOR SERN OH FOR A LTL BIT THEN BROUGHT THEM BACK E AS LOW APPROACHES BY DAWN. ELEVATED INSTABILITY COULD YIELD ISOLD TRW CLOSE TO BAROCLINIC ZONE. USED NAM QPF WITH DOWNWARD ADJ OVER PERRY COUNTY. RAINFALL AMOUNTS THRU 12Z WED RANGE FM 1.75 INCHES IN PERRY / MORGAN COUNTIES TAPERING BACK TO A QUARTER OF AN INCH FM RIO GRANDE TO MARIETTA. DO NOT FORESEE MUCH DROP IN TEMPS TNGT WITH READINGS HOLDING IN THE 50S AREAWIDE WITH DEEPER HOLLOW PERHAPS DROPPING INTO THE 40S. FLOOD WATCH WAS ISSUED FOR PORTIONS OF SERN OHIO. FOR MORE INFORMATION...SEE HYDROLOGY SECTION NEAR THE END OF THIS PRODUCT. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... COMPLEX SYSTEM MOVES THROUGH WED AND WED NT. SOUTHERN STREAM UPPER LEVEL LOW OPENS UP INTO A SHORT WAVE TROUGH AS IT LIFTS NE ON THE E SIDE OF THE LONG WAVE TROUGH POSITION. THIS IS GOOD NEWS AS THE SYSTEM PICKS UP SPEED...ENOUGH SO THAT PORTION OF THE CWA SE OF THE OH RIVER WILL NOT HAVE THE EXCESSIVE RAIN THAT WILL TAKE PLACE IN OH OVER THE NEXT THREE PERIODS. INDEED...FRONTOGENESIS IS SHOWN TO BE WEAK AS THE SYSTEM OPENS UP BUT GOOD UPPER DIV...MID LEVEL CONV OF Q AND DEFM STILL EXIST SUFFICIENTLY TO WARRANT CAT POPS FOR WED. SLOWED ONSET OF PRECIPITATION BY ABOUT 3 HRS BASED ON LATEST MODEL DATA BUT KEPT THE END TIME ABOUT THE SAME. ROLLED WITH HPC QPF WHICH WAS CLOSE TO THE NAM. THE NAM12 HAD WHAT WAS LIKELY TOO MUCH DETAIL FOR THIS PROJECTION IN TIME AS ASSOCIATED DYNAMICS ARE LIKELY TO CHANGE SOMEWHAT. EVENT TOTAL PRECIPITATION DROPS OFF SHARPLY ACROSS THE OHIO RIVER ON ACCOUNT OF THE INCREASED SPEED OF THE SYSTEM. STRONG WINDS AHEAD OF THE SYSTEM COUPLED WITH SMALL AMOUNT OF CAPE NECESSITATES THE MENTION OF THUNDER IN THE FORECAST. THE TIMING OF THE FRONT IS FAVORABLE FOR CONVECTION OVER THE EASTERN ROUGHLY HALF OF THE AREA BUT THE AMOUNT OF CLOUDS AND PRECIPITATION ASSOCIATED WITH THIS SYSTEM WILL LIKELY LIMIT DAYTIME HEATING SOMEWHAT. SPC HAS ISSUED A SLIGHT RISK FOR EXTREME SE PORTIONS OF AREA...THE MOST LIKELY TO HAVE SOME OPPORTUNITY FOR HEATING...AND WILL HIGHLIGHT THUSLY IN HWO. SFC WAVE LIFTS N OF THE AREA WED EVE AS OPEN SHORT WAVE LIFTS OUT. THIS WILL TAKE THE PRECIPITATION WITH IT AND BRING COLDER AIR IN ITS WAKE. THE COLD ER AIR WILL BE ENOUGH FOR A TRANSITION TO SNOW SHOWERS IN THE MOUNTAINS VERY LATE WED NT. STRONGEST WIND GUSTS WITH SYSTEM...NOTWITHSTANDING CONVECTION...WILL LIKELY BE TRANSFERRED DOWN AS THE COLD FRONT COMES THROUGH WED EVE, PEAK GUSTS OFF THE RUC ALGORITHM USING THE NAM ARE JUST BELOW CRITERIA FOR WIND ADVISORY ACROSS HIGHER TERRAIN SO ONE IS NOT NEEDED DUE TO THE SMALL SCALED NATURE THE EVENT. A NUMBER OF FAST MOVING CLIPPERS STREAK THROUGH IN THE FAST WNW FLOW ALOFT. MODELS SHOW A SMALL HINT OF ONE AS EARLY AS THU NT. A MORE ORGANIZED CLIPPER APPROACHES NEAR THE END OF THE PERIOD...A LITTLE SLOWER THAN PREVIOUS RUNS. ROLLED WITH THE MET FOR HIGHS WED...MOST NOTABLE DIFFERENCE BEING LOWER IN THE W WITH THE ONSET OF PRECIPITATION AND EVENTUAL FRONTAL PASSAGE THERE. TOOK NUMBERS UP TO THE LOWER MET FOR LOWS WED NT WHILE MAKING LITTLE CHANGE TO HIGHS THU. RAISED LOWS A BIT S THU NT WHILE LITTLE CHANGE WAS NEEDED TO HIGHS FRI OR LOWS FRI NT. && .LONG TERM /SATURDAY THROUGH MONDAY/... A FAST MOVING SHORT WAVE MOVES FROM THE CENTRAL PLAINS EAST THROUGH THE AREA ON SATURDAY. HPC GUIDANCE SUGGEST THE LOW TRACK RIGHT ACROSS WV...POSING A POSSIBILITY OF MIXED PRECIP ACROSS THE EXTREME NORTH. GFS AND ECMWF IN AGREEMENT BRINGING QPF ACROSS THE NORTHERN SECTIONS OF WV BY SAT 06-12Z...SPREADING SLOWLY SOUTH TO THE REST OF THE AREA THRU SUN 00Z. BOTH MODELS SHOW H8 FREEZING LINE JUST NORTH OF THE CWA AT 12Z SAT...WITH NORTHERLY FLOW PUSHING COLDER AIR AND FREEZING LINE SOUTH OF THE CWA BY SUN 12Z. THEREFORE...MIXED PRECIP OR SNOW SHOWERS WILL START ACROSS THE NORTHERN SECTIONS...WHILE RAIN SHOWERS WILL PREVAIL ACROSS THE SOUTHERN TWO THIRDS EARLY SATURDAY. ABOVE FREEZING TEMPS WILL PREVAIL AT THE LOWER LEVELS SATURDAY...CAUSING PRECIP TO PREVAIL AS LIQUID ACROSS THE ENTIRE AREA BY SAT AFTERNOON. PERHAPS THE NORTHEAST MOUNTAINS COULD SEE MIXED PRECIP SAT AFTERNOON AND ALL SNOW SAT EVENING. ANOTHER WEAK LOW PRESSURE MOVES INTO THE OH VALLEY ...PROVIDING A SMALL CHANCE OF PRECIP ON EASTER SUNDAY. HOWEVER...MODELS SOLUTIONS SPREAD FROM DAY 6-7...SO THERE IS LOW CONFIDENCE WITH THIS SYSTEM AND CHANGES IN FORECAST COULD OCCUR DURING THE NEXT COUPLE OF DAYS. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... VFR. GUSTY S/SE WINDS IN THE 20-30KT RANGE ARE THE STORY THE NEXT 24HRS. SUSTAIN SPEEDS WILL BE AOA 12KTS FM MID MRNG THRU THIS EVNG. THERE IS A POSSIBLITY OF -RA AT PKB AND HTS LATE MRNG INTO EARLY AFTN...BUT NO FLIGHT RESTRICTIONS ARE FORESEEN. BY THE END OF THE FCST...MVFR CIGS AND WIDESPREAD RA WILL BE KNOCKING ON THE DOOR OF HTS AND PKB. AVIATION OUTLOOK /AFTER 12Z WEDNESDAY/ IFR RA PSBL WED AS A COLD FRONT PASSES. TSTMS ARE PSBL AT ALL AIRPORTS WED SAVE FOR PKB/HTS. && .HYDROLOGY... HOISTED FLOOD WATCH FOR PARTS OF SERN OH DUE TO THE THREAT OF EXCESSIVE RAINFALL. FOLLOWING THE NAM OUTPUT WHICH YIELDS ONE TO TWO INCHES OVER THE WATCH AREA. DEEP MSTR SURGES NORTHWARD...WHILE A BOUNDARY SETS UP THROUGH CENTRAL OHIO AND IND. IN ADDITION...WAVES OF LOW PRESSURE RIDE ALONG THE BAROCLINIC ZONE. EXPECT STRONG RISES ON STREAMS AND CREEKS TUESDAY NIGHT WITH RIVERS BECOMING SWOLLEN OR POSSIBLY GOING INTO FLOOD WED. WE WILL BE CLOSELY WATCHING THE MUSKINGUM AND HOCKING RIVERS...ESPECIALLY SINCE THEIR RESPECTIVE HEADWATERS GET NAILED WITH TWO TO THREE INCHES OF QPF. IT WILL TAKE INTO THE WEEKEND OR PERHAPS LONGER BEFORE SECTIONS OF THE MUSKINGUM FALL BELOW ACTION STAGE. AT THIS POINT...THE GROUND CAN WITHSTAND 1.5 - 2.0 INCHES WITH AMOUNTS GREATER CAUSING HIGH WATER. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...FLOOD WATCH FROM 6 PM EDT THIS EVENING THROUGH WEDNESDAY AFTERNOON FOR OHZ066-067-075-076-083-084. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/29 NEAR TERM...29 SHORT TERM...TRM LONG TERM...TRM/ARJ AVIATION...29 HYDROLOGY...29 oh AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 206 PM MDT TUE MAR 18 2008 .DISCUSSION...19Z SURFACE ANALYSIS HAD WEAK LOW OVER SOUTHERN AB WITH TROUGH INTO CWA. SHORTWAVE ENERGY/COLD POOL ALOFT OVER MT/WY HEADING INTO THE CWA WITH STEEP LAPSE RATES AND LI/S FROM 0 TO -2. 18Z RUC HAD ABOUT 100 J/KG MLCAPE...SIGNS OF SPRING. POPCORN CU AND ISOLATED -SHRA EVIDENT ON 1KM VISIBLE/RADAR LOOPS. EXPECT ACTIVITY SOUTH OF I-90 TO BE QUITE DIURNAL...BUT STUFF IN NORTH WILL PERSIST OVERNIGHT AS A SECONDARY SHORTWAVE ZIPS INTO THE AREA. AS TEMPERATURES FALL PRECIPITATION WILL MIX WITH AND THEN CHANGE TO SNOW. LOWS TONIGHT WILL BE HELD UP BY CLOUDS AND RETURN TO WARM AIR ADVECTION/SOUTHWESTERLY FLOW AHEAD OF SECOND SHORTWAVE. WEDNESDAY...SECOND SHORTWAVE MOVES EAST OF CWA BY 00Z...CONTINUED POPS IN THE NORTH FOR -RASN IN THE MORNING...EXITING CWA VIA -RA IN THE AFTERNOON. HIGHS A TINY BIT COOLER THAN TODAY AS SURFACE TROUGH/COLD FRONT DROPS IN BEHIND WAVE. BREEZY SPOTS EXPECTED. WEDNESDAY NIGHT/THURSDAY...MAIN SHORT TERM EVENT FORESEEN AS BETTER ORGANIZED UPPER TROUGH MOVES FROM THE NORTHERN ROCKIES INTO NORTHERN PLAINS. LIFT BEGINS LATER WEDNESDAY NIGHT AND PEAKS DURING DAY THURSDAY WITH MODEST ISENTROPIC LIFT. TEMPERATURES WILL BE CRITICAL FOR THIS SYSTEM. NAM WARMER THAN GFS...WITH GFS TRENDING SLIGHTLY COOLER AND FURTHER SOUTH. HAVE GIVEN THE WINK TO GFS IN GENERAL. GFS SHOWS SIGNS OF WEAKLY COUPLED JET STRUCTURE. THIS PUTS AREAS NORTH OF I-90 IN THE LIKELY POP REGIME WITH A COUPLE INCHES OF SNOW POSSIBLE. STEEP LAPSE RATES WILL NEED TO BE MONITORED FOR POSSIBLE CONVECTIVE SNOW DEVELOPMENT. IF DYNAMIC COOLING CAN TAKE HOLD...COULD BE AN ADVISORY EVENT WHEN ALL IS SAID AND DONE. BREEZY NORTHWEST WINDS AS SURFACE LOW SLIPS FROM WY INTO NE...WHICH SHOULD DOWNSLOPE RAPID CITY LATE IN THE DAY. WENT COOLER THAN GUIDANCE FOR TEMPERATURES WITH LIKELY POPS...CLOSE TO GUIDANCE ELSEWHERE. EXTENDED...FAST NORTHWEST UPPER LEVEL FLOW WILL DOMINATE THE NORTHERN PLAINS DURING THE EXTENDED PERIOD. SEVERAL WEAK DISTURBANCES IN THIS FLOW WILL MOVE THROUGH THE REGION FOR THE END OF THE WORK WEEK INTO THE WEEKEND...BRINGING AN ALMOST DAILY CHANCE OF PRECIPITATION TO MUCH OF THE AREA. TEMPERATURES WILL BE NEAR TO SLIGHTLY BELOW AVERAGE. && .AVIATION...ISOLATED RAIN OR SNOW SHOWERS THIS EVENING AND OVERNIGHT ACROSS THE CWA MAY BRING SOME MVFR CIGS TO THOSE AREAS. OTHERWISE...VFR CONDITIONS WILL CONTINUE THROUGH WEDNESDAY MORNING. A COLD FRONT WILL PASS THROUGH THE NORTHERN PLAINS WEDNESDAY MORNING...INCREASING NORTHWEST SURFACE WINDS ACROSS THE SOUTH DAKOTA PLAINS TO 15 TO 25 MPH FOR MOST OF THE DAY. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ HELGESON/RUDGE sd AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 238 PM MDT MON MAR 17 2008 .DISCUSSION...20Z SURFACE ANALYSIS SHOWS BOUNDARY CURRENTLY OVER EASTERN MONTANA. A CU FIELD HAS DEVELOPED OVER HARDING COUNTY OVER THE PAST FEW HOURS. RUC FORECAST SOUNDING IS INDICATING AROUND 75 J/KG OF CAPE OVER THIS AREA THIS AFTERNOON. DO NOT EXPECT MUCH MORE THAN A FEW SPRINKLES OUT OF THIS ACTIVITY THE REST OF THIS AFTERNOON. ACTIVITY WILL TAPER OFF AFTER SUNSET. TEMPERATURES HAVE WARMED INTO THE UPPER 40 ACROSS NORTHWEST AND WEST CENTRAL SD AS WELL AS PORTIONS OF NORTHEAST WYOMING. SHORTWAVE...EVIDENT ON WATER VAPOR IMAGERY...OVER EASTERN MONTANA WILL MOVE OVER NORTHERN PORTIONS OF THE CWA THIS EVENING BRINGING ISOLATED SPRINKLES OR FLURRIES TO NORTHWESTERN SOUTH DAKOTA. TROF OF LOW PRESSURE ACROSS THE CENTRAL CONUS WILL CONTINUE TO PROGRESS EASTWARD THIS EVENING AS A WEAK RIDGE OF HIGH PRESSURE BUILDS INTO THE CWA ON TUESDAY. TEMPERATURES WILL BE SEASONAL ACROSS WESTERN SOUTH DAKOTA AND NORTHEASTERN WYOMING ON TUESDAY. WEAK DOWNSLOPING WILL OCCUR ALONG THE EASTERN BLACK HILLS ON TUESDAY ALLOWING TEMPERATURES TO WARM INTO THE MID TO UPPER 50S. THE NEXT SHORTWAVE SWINGS INTO NORTHWESTERN PORTIONS OF THE CWA ON WEDNESDAY BRINGING ANOTHER CHANCE OF PRECIPITATING TO THE AREA. PRECIP WILL START OUT AS SNOW IN THE EARLY MORNING AND SWITCH OVER TO RAIN BY THE AFTERNOON. ANOTHER SHORTWAVE WILL APPROACH THE CWA ON THURSDAY AS A SURFACE LOW DEVELOPS OVER EASTERN WYOMING BRINGING A SLIGHT CHANCE OF RAIN OR SNOW TO WESTERN SOUTH DAKOTA. EXTENDED...UPPER LEVEL FLOW WILL BECOME FAIRLY PROGRESSIVE IN THE EXTENDED TIME FRAME. SEVERAL WEAK DISTURBANCES WILL MOVE THROUGH THE REGION FROM THURSDAY THROUGH THE WEEKEND...BRINGING AN ALMOST DAILY CHANCE OF PRECIPITATION. STRONGEST SHORTWAVE STILL LOOKS LIKE IT WILL PASS THROUGH THE FORECAST AREA ON THURSDAY. TEMPERATURES WILL START TO COOL FOR THE LAST PART OF THE WORK WEEK...WITH BELOW AVERAGE TEMPERATURES EXPECTED FOR THE WEEKEND. && .AVIATION...VFR CONDITIONS EXPECTED THROUGH TUESDAY MORNING. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ WETENKAMP/RUDGE sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 743 PM CDT TUE MAR 18 2008 .UPDATE... CLEARING THE TORNADO WATCH WITH COLD FRONT NOW THROUGH ALL OF NORTH TEXAS. OTHERWISE HAVE MADE MINOR CHANGES TO LOWER LOW TEMPS A LITTLE AND TWEAKS TO SKY/POPS THROUGH TONIGHT. UPPER LEVEL LOW STILL BACK IN SW TEXAS WILL BE MOVING OVER NORTH TEXAS DURING THE OVERNIGHT HOURS. STRONG FRONTOGENESIS ASSOCIATED WITH THE CORE OF THE UPPER LEVEL LOW WILL MAINTAIN UPWARD VERTICAL MOTIONS OVER THE AREA AND SQUEEZE OUT THE REMAINING MOISTURE ALOFT. AREAS OF MODERATE RAIN ARE EXPECTED TO CONTINUE...BUT RAINFALL RATES SHOULD STAY LESS THAN 1/4 INCH AN HOUR...WITH ADDITIONAL TOTALS OF A HALF INCH TO AN INCH NORTH OF A COMANCHE TO CANTON LINE. RAIN TOTALS WILL BE LESS THAN A HALF INCH IN THE SOUTHERN ZONES. TR.92 && .PREV DISCUSSION... /ISSUED 659 PM CDT TUE MAR 18 2008/ UPDATE... TORNADO WATCH WILL CONTINUE FOR ANDERSON AND HENDERSON COUNTY FOR AT LEAST THE NEXT HOUR BEFORE WE CLEAR IT. OTHERWISE...STRONG PRESSURE RISES ARE OCCURRING AND RUC FORECASTS SHOW 925 MB WINDS APPROACHING 50 KNOTS TONIGHT. STRONG ISENTROPIC DESCENT AND COLD ADVECTION WILL FAVOR SOME MIXING OF THIS WIND DOWN TO THE SURFACE SO HAVE ISSUED A WIND ADVISORY FOR THE ENTIRE AREA THROUGH 4 AM. NO OTHER CHANGES AT THIS TIME. TR.92 PREV DISCUSSION... /ISSUED 550 PM CDT TUE MAR 18 2008/ AVIATION... 550 PM ACT SEEING ABOUT THE LAST HOUR OR TWO OF THE WORST TSTMS. DFW AREA ALSO HAS THE STRONGEST STORMS TO THE EAST. EXPECT RAIN TO CONTINUE IN METROPLEX FOR NEXT 3-4 HOURS WITH SOME EMBEDDED TSTMS...THEN TAPER OFF TO INTERMITTENT SHOWERS OVERNIGHT. RAIN SHOULD END AROUND SUNRISE AS UPPER SYSTEM FINALLY MOVES EAST. MVFR CEILINGS SHOULD CONTINUE THROUGH ABOUT MIDNIGHT WHEN DEEPER LLVL DRY AIR CAUSES THEM TO LIFT TO VFR. 84 UPDATE... 530 PM HAVE UPDATED TO INCLUDE THE NEW TOR BOX FOR THE EXTREME EAST. TORNADO THREAT ONLY WILL END IN A COUPLE HOURS AND WATCH WILL BE CANCELED WELL BEFORE THE LISTED EXPIRATION TIME. OTHERWISE HAVE AMENDED THE FORECAST TO INCREASE WIND SPEEDS TONIGHT...BUT WILL HOLD OFF ON A WIND ADVISORY FOR NOW...AWAITING TO SEE ISALLOBARIC TRENDS UNFOLD WITH DYNAMIC SYSTEM MOVING ACROSS. TR.92 DISCUSSION... AREA OF RAIN AND THUNDERSTORMS CURRENTLY MOVING SOUTH TO NORTH OVER MUCH OF NORTH TEXAS IS BEING FED BY A 50+ KT LOW LEVEL JET. COLD FRONT CONTINUES ITS SLOW MARCH SOUTHEASTWARD ACROSS THE AREA. AREAS AHEAD OF THE FRONT STILL HAVE A CHANCE FOR SEVERE WEATHER... ALTHOUGH SO FAR HEAVY RAIN AND FLASH FLOODING HAVE PROVED TO BE THE MAIN HAZARDS. MOST AREAS HAVE RECEIVED BETWEEN ONE AND TWO INCHES SO FAR WITH ANOTHER INCH OR MORE STILL POSSIBLE. EVEN AS THE FRONT EXITS STAGE RIGHT...WE WILL SEE RAIN CHANCES INTO THE EVENING HOURS AND OVERNIGHT AS THE MAIN UPPER LOW ROTATES OVER THE REGION. LARGELY UNI-DIRECTIONAL SHEAR WILL CONTINUE TO PROMOTE TRAINING OF CELLS AND FLASH FLOODING. WRAP-AROUND PRECIP WILL LINGER IN THE NORTHEAST INTO THE EARLY MORNING HOURS BUT SHOULD SHUT OFF RATHER QUICKLY. UPPER PATTERN WILL BECOME FLAT AND ZONAL FROM WEDNESDAY NIGHT THROUGH THE WEEKEND. PLEASANT TEMPERATURES ARE EXPECTED WITH SOUTHERLY FLOW RETURNING THURSDAY MORNING. CLEAR SKIES WILL ALLOW FOR AFTERNOON READINGS IN THE 70S THURSDAY AND FRIDAY. THERE WILL BE A SLIGHT COOL DOWN OVER THE WEEKEND AS A WEAK FRONT MOVES THROUGH THE AREA. RAIN CHANCES WITH THIS SYSTEM LOOK LOWER THAN PREVIOUSLY THOUGHT WITH MOST OF THE ENERGY WELL TO OUR NORTH. HAVE LEFT SLIGHT CHANCE POPS IN FOR NOW AND WILL CONTINUE TO WATCH THIS SYSTEM. QUIET WEATHER IS EXPECTED FOR THE BEGINNING OF NEXT WEEK WITH THE MAIN STORM TRACK STAYING ACROSS THE NORTHERN PLAINS. SH/13 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 44 66 43 72 50 / 100 0 0 0 5 WACO, TX 45 69 41 72 52 / 60 0 0 0 5 PARIS, TX 45 64 41 69 46 / 100 20 0 0 5 DENTON, TX 43 66 40 72 49 / 100 5 0 0 5 MCKINNEY, TX 45 66 39 73 48 / 100 20 0 0 5 DALLAS, TX 44 67 44 73 52 / 100 5 0 0 5 TERRELL, TX 45 65 40 72 50 / 90 10 0 0 5 CORSICANA, TX 46 67 41 73 49 / 60 0 0 0 5 TEMPLE, TX 46 70 40 72 48 / 50 0 0 0 5 && .FWD WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 7 AM CDT WEDNESDAY FOR THE FOLLOWING ZONES: TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175. WIND ADVISORY UNTIL 4 AM CDT WEDNESDAY FOR THE FOLLOWING ZONES: TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175. && $$ 99/99 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 659 PM CDT TUE MAR 18 2008 .UPDATE... TORNADO WATCH WILL CONTINUE FOR ANDERSON AND HENDERSON COUNTY FOR AT LEAST THE NEXT HOUR BEFORE WE CLEAR IT. OTHERWISE...STRONG PRESSURE RISES ARE OCCURRING AND RUC FORECASTS SHOW 925 MB WINDS APPROACHING 50 KNOTS TONIGHT. STRONG ISENTROPIC DESCENT AND COLD ADVECTION WILL FAVOR SOME MIXING OF THIS WIND DOWN TO THE SURFACE SO HAVE ISSUED A WIND ADVISORY FOR THE ENTIRE AREA THROUGH 4 AM. NO OTHER CHANGES AT THIS TIME. TR.92 && .PREV DISCUSSION... /ISSUED 550 PM CDT TUE MAR 18 2008/ AVIATION... 550 PM ACT SEEING ABOUT THE LAST HOUR OR TWO OF THE WORST TSTMS. DFW AREA ALSO HAS THE STRONGEST STORMS TO THE EAST. EXPECT RAIN TO CONTINUE IN METROPLEX FOR NEXT 3-4 HOURS WITH SOME EMBEDDED TSTMS...THEN TAPER OFF TO INTERMITTENT SHOWERS OVERNIGHT. RAIN SHOULD END AROUND SUNRISE AS UPPER SYSTEM FINALLY MOVES EAST. MVFR CEILINGS SHOULD CONTINUE THROUGH ABOUT MIDNIGHT WHEN DEEPER LLVL DRY AIR CAUSES THEM TO LIFT TO VFR. 84 UPDATE... 530 PM HAVE UPDATED TO INCLUDE THE NEW TOR BOX FOR THE EXTREME EAST. TORNADO THREAT ONLY WILL END IN A COUPLE HOURS AND WATCH WILL BE CANCELED WELL BEFORE THE LISTED EXPIRATION TIME. OTHERWISE HAVE AMENDED THE FORECAST TO INCREASE WIND SPEEDS TONIGHT...BUT WILL HOLD OFF ON A WIND ADVISORY FOR NOW...AWAITING TO SEE ISALLOBARIC TRENDS UNFOLD WITH DYNAMIC SYSTEM MOVING ACROSS. TR.92 DISCUSSION... AREA OF RAIN AND THUNDERSTORMS CURRENTLY MOVING SOUTH TO NORTH OVER MUCH OF NORTH TEXAS IS BEING FED BY A 50+ KT LOW LEVEL JET. COLD FRONT CONTINUES ITS SLOW MARCH SOUTHEASTWARD ACROSS THE AREA. AREAS AHEAD OF THE FRONT STILL HAVE A CHANCE FOR SEVERE WEATHER... ALTHOUGH SO FAR HEAVY RAIN AND FLASH FLOODING HAVE PROVED TO BE THE MAIN HAZARDS. MOST AREAS HAVE RECEIVED BETWEEN ONE AND TWO INCHES SO FAR WITH ANOTHER INCH OR MORE STILL POSSIBLE. EVEN AS THE FRONT EXITS STAGE RIGHT...WE WILL SEE RAIN CHANCES INTO THE EVENING HOURS AND OVERNIGHT AS THE MAIN UPPER LOW ROTATES OVER THE REGION. LARGELY UNI-DIRECTIONAL SHEAR WILL CONTINUE TO PROMOTE TRAINING OF CELLS AND FLASH FLOODING. WRAP-AROUND PRECIP WILL LINGER IN THE NORTHEAST INTO THE EARLY MORNING HOURS BUT SHOULD SHUT OFF RATHER QUICKLY. UPPER PATTERN WILL BECOME FLAT AND ZONAL FROM WEDNESDAY NIGHT THROUGH THE WEEKEND. PLEASANT TEMPERATURES ARE EXPECTED WITH SOUTHERLY FLOW RETURNING THURSDAY MORNING. CLEAR SKIES WILL ALLOW FOR AFTERNOON READINGS IN THE 70S THURSDAY AND FRIDAY. THERE WILL BE A SLIGHT COOL DOWN OVER THE WEEKEND AS A WEAK FRONT MOVES THROUGH THE AREA. RAIN CHANCES WITH THIS SYSTEM LOOK LOWER THAN PREVIOUSLY THOUGHT WITH MOST OF THE ENERGY WELL TO OUR NORTH. HAVE LEFT SLIGHT CHANCE POPS IN FOR NOW AND WILL CONTINUE TO WATCH THIS SYSTEM. QUIET WEATHER IS EXPECTED FOR THE BEGINNING OF NEXT WEEK WITH THE MAIN STORM TRACK STAYING ACROSS THE NORTHERN PLAINS. SH/13 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 47 66 43 72 50 / 100 0 0 0 5 WACO, TX 46 69 41 72 52 / 60 0 0 0 5 PARIS, TX 45 64 41 69 46 / 100 20 0 0 5 DENTON, TX 45 66 40 72 49 / 100 5 0 0 5 MCKINNEY, TX 45 66 39 73 48 / 100 20 0 0 5 DALLAS, TX 49 67 44 73 52 / 100 5 0 0 5 TERRELL, TX 48 65 40 72 50 / 90 10 0 0 5 CORSICANA, TX 47 67 41 73 49 / 70 0 0 0 5 TEMPLE, TX 46 70 40 72 48 / 40 0 0 0 5 && .FWD WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR THE FOLLOWING ZONES: TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175. WIND ADVISORY UNTIL 4 AM CDT WEDNESDAY FOR THE FOLLOWING ZONES: TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175. && $$ 99/99 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 200 AM CDT TUE MAR 18 2008 .UPDATE... COLD FRONT IS FINALLY STARTING TO MAKE SOME PROGRESS SOUTHEAST. THUNDERSTORMS WILL CONTINUE TO FORM ALONG AND BEHIND THE FRONT. THE POTENTIAL FOR SEVERE STORMS WILL CONTINUE ALONG AND JUST AHEAD OF THE FRONT SO WILL KEEP SEVERE MENTIONED OVERNIGHT AND SEND OUT A QUICK UPDATE TO ADD TORNADO WATCH 129 VALID UNTIL 9 AM FOR LOCATIONS WEST OF INTERSTATE 35 AND SOUTH OF INTERSTATE 20. WILL ALSO LOWER OVERNIGHT POPS EAST OF INTERSTATE 35. .79... && .AVIATION... 1128 PM TAF SITES CONTINUE TO BE SURROUNDED BY PRECIP. STORMS WEST OF SAN ANGELO HINTING AT FORMING A SQUALL LINE...AND IF IT FORMS IT COULD BE INTO TAF SITES JUST BEFORE SUNRISE. WEAK SHOWERS ALSO FORMING IN SOUTHEASTERN NORTH TX...SO WILL CONTINUE TO EXPECT THE PRECIP TO FILL IN ACROSS THE TAF SITES THIS MORNING. 84 && .UPDATE... 933 PM ACTIVITY OVER THE NE CWA HAS DIMINISHED AS LOW LEVEL CONVERGENCE WEAKENS WITH THE EXIT OF THE FIRST SHORTWAVE. THE LOW LEVEL FLOW HAS ALSO WEAKENED IN THE WESTERN ZONES IN RESPONSE TO THE NEXT SHORTWAVE TROUGH MOVING INTO SW TEXAS. THIS HAS TEMPORARILY LESSENED THE TORNADO THREAT...BUT SHORT TERM MODEL GUIDANCE DOES INDICATE LOW LEVEL SHEAR INTENSIFYING RAPIDLY AFTER MIDNIGHT - ESPECIALLY ACROSS THE SW AND SOUTHERN COUNTIES WHERE A SURFACE LOW CROSSES. CONVECTION WILL CONTINUE TO DEVELOP INTO THE WESTERN COUNTIES DURING THE NEXT FEW HOURS ALONG SLOW MOVING COLD FRONT. STILL EXPECT RAIN AND STORMS TO ARRIVE AT THE I-35 CORRIDOR AFTER MIDNIGHT WITH WATCH BOXES EXPANDING EASTWARD. FOR THE UPDATE...HAVE ADDED WISE AND PARKER COUNTIES TO THE FLASH FLOOD WATCH WITH GUIDANCE SHIFTING AXIS OF HEAVY RAIN TONIGHT ALONG AND BEHIND THE FRONT WHICH SHOULD BE DRAPED ACROSS THE I-35 CORRIDOR BY SUNRISE. HAVE ALSO TRIMMED THE SW COUNTIES OFF TORNADO WATCH 125 WITH ADDITIONAL CONVECTIVE DEVELOPMENT APPEARING UNLIKELY THROUGH MIDNIGHT. TR.92 && .PREV DISCUSSION... /ISSUED 855 PM CDT MON MAR 17 2008/ AVIATION... 855 PM BACKING OFF ON THE THUNDER AND RAIN THIS EVENING FOR THE TAF SITES. NEWEST RUC INDICATES THAT THE WEAKENING PRECIP ACROSS THE AREA WILL CONTINUE TO WEAKEN AND HEAVY RAIN WILL NOT GET GOING UNTIL AFTER MIDNIGHT. 00Z NAM JUST COMING IN BUT HINTS AT THE SAME OUTCOME. THERE WILL STILL BE SOME SHOWERS IN THE VICINITY THIS EVENING. 84 UPDATE... 600 PM UPDATING TO INCLUDE TORNADO WATCH IN THE EAST. WATCHING STORMS EXPLODE IN LOW LEVEL CONFLUENCE ZONE OVER NORTHEASTERN COUNTIES AND THESE STORMS ARE IMMERSED WITHIN FAVORABLE ENVIRONMENT FOR LOW LEVEL ROTATION. WARM FRONT IS IN THE PARIS VICINITY ATTM WHICH WILL ENHANCE TORNADO THREAT. WATCH DOES NOT INCLUDE THE IMMEDIATE METROPLEX AREA...BUT WILL NOT HESITATE TO EXPAND IT WESTWARD BASED ON RADAR TRENDS DURING THE NEXT COUPLE HOURS...BUT THINKING IS TOR THREAT WILL BE JUST EAST THROUGH THE EVENING HOURS. TR.92 PREV DISCUSSION... /ISSUED 545 PM CDT MON MAR 17 2008/ AVIATION... 545 PM THIS TAF PACKAGE WILL CONTINUE WITH PREVIOUS TRENDS. EXPECT PRECIP TO CONTINUE TO INCREASE WITH METROPLEX AIRPORTS SEEING SHOWERS WITH EMBEDDED THUNDERSTORMS BY MID-LATE EVENING CONTINUING OVERNIGHT. CEILINGS WILL CONTINUE TO DECREASE THIS EVENING AND EXPECT MVFR CIGS BY LATE EVENING WITH A POSSIBLE DIP INTO IFR RANGE DEPENDING ON PRECIP. FRONT SHOULD PASS METROPLEX JUST AFTER SUNRISE TUESDAY BUT PRECIP WILL CONTINUE LIKELY THROUGH MIDDAY. 84 DISCUSSION... 242 PM A LINE OF SHOWERS AND THUNDERSTORMS CONTINUES TO DEVELOP ALONG A DRY LINE WHICH STRETCHED FROM ALTUS TO SWEETWATER TO NEAR FORT STOCKTON. A WARM FRONT RAN ROUGHLY ALONG A LINE FROM ALTUS TO ARDMORE TO PARIS. WATER VAPOR IMAGERY SHOWS A POTENT UPPER LOW SPINNING OVER ARIZONA. THIS FEATURE IS FORECAST TO DIP SOUTHEAST INTO NORTHERN MEXICO BEFORE MOVING ACROSS TEXAS TOMORROW. AS THIS OCCURS...LARGE SCALE ASCENT WILL INCREASE AND SHOWERS AND THUNDERSTORMS WILL EXPAND IN COVERAGE. ATMOSPHERE OVER NORTH TEXAS REMAINS CAPPED BUT IS IN THE PROCESS OF ERODING. A 19Z SOUNDING WILL CONFIRM THIS. VERY MOIST GULF AIR HAS ADVECTED ACROSS MUCH OF THE CWA WITH DEWPOINTS COMMONLY IN THE 60S. SKIES ARE CLEARING ALONG AND AHEAD OF THE DRY LINE ALLOWING FOR DECENT INSOLATION. RESULTANT SBCAPES OF AT LEAST 2000 J/KG AND AMPLE SHEAR WILL FOSTER DISCRETE SUPERCELLS ALONG THE DRY LINE WITH THE POTENTIAL TO PRODUCE LARGE HAIL...DAMAGING WINDS...AND TORNADOES. A SEVERE THUNDERSTORM WATCH IS ALREADY IN EFFECT FOR EXTREME WESTERN PORTIONS OF NORTH TEXAS. STORM MODE WILL TRANSITION TO A LINEAR MCS AS THE COLD FRONT CATCHES UP WITH THE DRY LINE LATE TONIGHT. EXPECT WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS NORTH TEXAS OVERNIGHT AND INTO TOMORROW WITH VERY MOIST AIR IN PLACE. GREATEST THREAT WILL THEN BECOME FLASH FLOODING WITH HPC FORECASTING 24 HR QPF AMOUNTS AS HIGH AS 5 INCHES ALONG THE RED RIVER. MOST NORTH TEXANS CAN EXPECT RAINFALL AMOUNTS BETWEEN 2 AND 4 INCHES BEFORE ALL IS SAID AND DONE. A FLASH FLOOD WATCH REMAINS IN EFFECT FROM 00Z THIS EVENING THROUGH WEDNESDAY MORNING FOR MUCH OF THE AREA. RAIN PROCESSES WILL BEGIN TO SHUT DOWN FROM WEST TO EAST WEDNESDAY MORNING AS THE UPPER LOW MOVES OFF TO THE NORTHEAST. SOME WRAP- AROUND PRECIP IS LIKELY ACROSS THE NORTHERN COUNTIES. UPPER LEVEL PATTERNS FLATTENS OUT FOR THE WEDNESDAY THROUGH FRIDAY TIME FRAME WITH HIGH TEMPERATURES WARMING INTO THE 70S THURSDAY AND FRIDAY. THE NEXT CHANCE FOR RAIN FOR NORTH TEXAS WILL OCCUR OVER THE WEEKEND AS A WEAK SHORTWAVE PASSES BY IN WNW FLOW ALOFT. SH/13 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 65 65 43 66 41 / 100 100 90 5 0 WACO, TX 66 66 46 68 42 / 100 100 80 0 0 PARIS, TX 66 66 44 59 38 / 100 100 100 10 0 DENTON, TX 63 63 42 64 39 / 100 100 80 5 0 MCKINNEY, TX 65 65 45 64 37 / 100 100 90 5 0 DALLAS, TX 65 65 44 67 45 / 100 100 90 5 0 TERRELL, TX 66 66 42 64 40 / 100 100 90 5 0 CORSICANA, TX 67 67 44 67 41 / 100 100 90 5 0 TEMPLE, TX 66 66 44 71 41 / 100 100 80 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR THE FOLLOWING ZONES: TXZ092>095-103>107-118>123-130>135-141>148-156>162-174-175. FLASH FLOOD WATCH UNTIL 1 AM CDT TUESDAY FOR THE FOLLOWING ZONES: TXZ102-117. && $$ tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1128 PM CDT MON MAR 17 2008 .AVIATION... 1128 PM TAF SITES CONTINUE TO BE SURROUNDED BY PRECIP. STORMS WEST OF SAN ANGELO HINTING AT FORMING A SQUALL LINE...AND IF IT FORMS IT COULD BE INTO TAF SITES JUST BEFORE SUNRISE. WEAK SHOWERS ALSO FORMING IN SOUTHEASTERN NORTH TX...SO WILL CONTINUE TO EXPECT THE PRECIP TO FILL IN ACROSS THE TAF SITES THIS MORNING. 84 && .UPDATE... 933 PM ACTIVITY OVER THE NE CWA HAS DIMINISHED AS LOW LEVEL CONVERGENCE WEAKENS WITH THE EXIT OF THE FIRST SHORTWAVE. THE LOW LEVEL FLOW HAS ALSO WEAKENED IN THE WESTERN ZONES IN RESPONSE TO THE NEXT SHORTWAVE TROUGH MOVING INTO SW TEXAS. THIS HAS TEMPORARILY LESSENED THE TORNADO THREAT...BUT SHORT TERM MODEL GUIDANCE DOES INDICATE LOW LEVEL SHEAR INTENSIFYING RAPIDLY AFTER MIDNIGHT - ESPECIALLY ACROSS THE SW AND SOUTHERN COUNTIES WHERE A SURFACE LOW CROSSES. CONVECTION WILL CONTINUE TO DEVELOP INTO THE WESTERN COUNTIES DURING THE NEXT FEW HOURS ALONG SLOW MOVING COLD FRONT. STILL EXPECT RAIN AND STORMS TO ARRIVE AT THE I-35 CORRIDOR AFTER MIDNIGHT WITH WATCH BOXES EXPANDING EASTWARD. FOR THE UPDATE...HAVE ADDED WISE AND PARKER COUNTIES TO THE FLASH FLOOD WATCH WITH GUIDANCE SHIFTING AXIS OF HEAVY RAIN TONIGHT ALONG AND BEHIND THE FRONT WHICH SHOULD BE DRAPED ACROSS THE I-35 CORRIDOR BY SUNRISE. HAVE ALSO TRIMMED THE SW COUNTIES OFF TORNADO WATCH 125 WITH ADDITIONAL CONVECTIVE DEVELOPMENT APPEARING UNLIKELY THROUGH MIDNIGHT. TR.92 && .PREV DISCUSSION... /ISSUED 855 PM CDT MON MAR 17 2008/ AVIATION... 855 PM BACKING OFF ON THE THUNDER AND RAIN THIS EVENING FOR THE TAF SITES. NEWEST RUC INDICATES THAT THE WEAKENING PRECIP ACROSS THE AREA WILL CONTINUE TO WEAKEN AND HEAVY RAIN WILL NOT GET GOING UNTIL AFTER MIDNIGHT. 00Z NAM JUST COMING IN BUT HINTS AT THE SAME OUTCOME. THERE WILL STILL BE SOME SHOWERS IN THE VICINITY THIS EVENING. 84 UPDATE... 600 PM UPDATING TO INCLUDE TORNADO WATCH IN THE EAST. WATCHING STORMS EXPLODE IN LOW LEVEL CONFLUENCE ZONE OVER NORTHEASTERN COUNTIES AND THESE STORMS ARE IMMERSED WITHIN FAVORABLE ENVIRONMENT FOR LOW LEVEL ROTATION. WARM FRONT IS IN THE PARIS VICINITY ATTM WHICH WILL ENHANCE TORNADO THREAT. WATCH DOES NOT INCLUDE THE IMMEDIATE METROPLEX AREA...BUT WILL NOT HESITATE TO EXPAND IT WESTWARD BASED ON RADAR TRENDS DURING THE NEXT COUPLE HOURS...BUT THINKING IS TOR THREAT WILL BE JUST EAST THROUGH THE EVENING HOURS. TR.92 PREV DISCUSSION... /ISSUED 545 PM CDT MON MAR 17 2008/ AVIATION... 545 PM THIS TAF PACKAGE WILL CONTINUE WITH PREVIOUS TRENDS. EXPECT PRECIP TO CONTINUE TO INCREASE WITH METROPLEX AIRPORTS SEEING SHOWERS WITH EMBEDDED THUNDERSTORMS BY MID-LATE EVENING CONTINUING OVERNIGHT. CEILINGS WILL CONTINUE TO DECREASE THIS EVENING AND EXPECT MVFR CIGS BY LATE EVENING WITH A POSSIBLE DIP INTO IFR RANGE DEPENDING ON PRECIP. FRONT SHOULD PASS METROPLEX JUST AFTER SUNRISE TUESDAY BUT PRECIP WILL CONTINUE LIKELY THROUGH MIDDAY. 84 DISCUSSION... 242 PM A LINE OF SHOWERS AND THUNDERSTORMS CONTINUES TO DEVELOP ALONG A DRY LINE WHICH STRETCHED FROM ALTUS TO SWEETWATER TO NEAR FORT STOCKTON. A WARM FRONT RAN ROUGHLY ALONG A LINE FROM ALTUS TO ARDMORE TO PARIS. WATER VAPOR IMAGERY SHOWS A POTENT UPPER LOW SPINNING OVER ARIZONA. THIS FEATURE IS FORECAST TO DIP SOUTHEAST INTO NORTHERN MEXICO BEFORE MOVING ACROSS TEXAS TOMORROW. AS THIS OCCURS...LARGE SCALE ASCENT WILL INCREASE AND SHOWERS AND THUNDERSTORMS WILL EXPAND IN COVERAGE. ATMOSPHERE OVER NORTH TEXAS REMAINS CAPPED BUT IS IN THE PROCESS OF ERODING. A 19Z SOUNDING WILL CONFIRM THIS. VERY MOIST GULF AIR HAS ADVECTED ACROSS MUCH OF THE CWA WITH DEWPOINTS COMMONLY IN THE 60S. SKIES ARE CLEARING ALONG AND AHEAD OF THE DRY LINE ALLOWING FOR DECENT INSOLATION. RESULTANT SBCAPES OF AT LEAST 2000 J/KG AND AMPLE SHEAR WILL FOSTER DISCRETE SUPERCELLS ALONG THE DRY LINE WITH THE POTENTIAL TO PRODUCE LARGE HAIL...DAMAGING WINDS...AND TORNADOES. A SEVERE THUNDERSTORM WATCH IS ALREADY IN EFFECT FOR EXTREME WESTERN PORTIONS OF NORTH TEXAS. STORM MODE WILL TRANSITION TO A LINEAR MCS AS THE COLD FRONT CATCHES UP WITH THE DRY LINE LATE TONIGHT. EXPECT WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS NORTH TEXAS OVERNIGHT AND INTO TOMORROW WITH VERY MOIST AIR IN PLACE. GREATEST THREAT WILL THEN BECOME FLASH FLOODING WITH HPC FORECASTING 24 HR QPF AMOUNTS AS HIGH AS 5 INCHES ALONG THE RED RIVER. MOST NORTH TEXANS CAN EXPECT RAINFALL AMOUNTS BETWEEN 2 AND 4 INCHES BEFORE ALL IS SAID AND DONE. A FLASH FLOOD WATCH REMAINS IN EFFECT FROM 00Z THIS EVENING THROUGH WEDNESDAY MORNING FOR MUCH OF THE AREA. RAIN PROCESSES WILL BEGIN TO SHUT DOWN FROM WEST TO EAST WEDNESDAY MORNING AS THE UPPER LOW MOVES OFF TO THE NORTHEAST. SOME WRAP- AROUND PRECIP IS LIKELY ACROSS THE NORTHERN COUNTIES. UPPER LEVEL PATTERNS FLATTENS OUT FOR THE WEDNESDAY THROUGH FRIDAY TIME FRAME WITH HIGH TEMPERATURES WARMING INTO THE 70S THURSDAY AND FRIDAY. THE NEXT CHANCE FOR RAIN FOR NORTH TEXAS WILL OCCUR OVER THE WEEKEND AS A WEAK SHORTWAVE PASSES BY IN WNW FLOW ALOFT. SH/13 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 65 65 43 66 41 / 100 100 90 5 0 WACO, TX 66 66 46 68 42 / 100 100 80 0 0 PARIS, TX 66 66 44 59 38 / 100 100 100 10 0 DENTON, TX 63 63 42 64 39 / 100 100 80 5 0 MCKINNEY, TX 65 65 45 64 37 / 100 100 90 5 0 DALLAS, TX 65 65 44 67 45 / 100 100 90 5 0 TERRELL, TX 66 66 42 64 40 / 100 100 90 5 0 CORSICANA, TX 67 67 44 67 41 / 100 100 90 5 0 TEMPLE, TX 66 66 44 71 41 / 100 100 80 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR THE FOLLOWING ZONES: TXZ092>095-103>107-118>123-130>135-141>148-156>162-174-175. FLASH FLOOD WATCH UNTIL 1 AM CDT TUESDAY FOR THE FOLLOWING ZONES: TXZ102-117. && $$ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 933 PM CDT MON MAR 17 2008 .UPDATE... ACTIVITY OVER THE NE CWA HAS DIMINISHED AS LOW LEVEL CONVERGENCE WEAKENS WITH THE EXIT OF THE FIRST SHORTWAVE. THE LOW LEVEL FLOW HAS ALSO WEAKENED IN THE WESTERN ZONES IN RESPONSE TO THE NEXT SHORTWAVE TROUGH MOVING INTO SW TEXAS. THIS HAS TEMPORARILY LESSENED THE TORNADO THREAT...BUT SHORT TERM MODEL GUIDANCE DOES INDICATE LOW LEVEL SHEAR INTENSIFYING RAPIDLY AFTER MIDNIGHT - ESPECIALLY ACROSS THE SW AND SOUTHERN COUNTIES WHERE A SURFACE LOW CROSSES. CONVECTION WILL CONTINUE TO DEVELOP INTO THE WESTERN COUNTIES DURING THE NEXT FEW HOURS ALONG SLOW MOVING COLD FRONT. STILL EXPECT RAIN AND STORMS TO ARRIVE AT THE I-35 CORRIDOR AFTER MIDNIGHT WITH WATCH BOXES EXPANDING EASTWARD. FOR THE UPDATE...HAVE ADDED WISE AND PARKER COUNTIES TO THE FLASH FLOOD WATCH WITH GUIDANCE SHIFTING AXIS OF HEAVY RAIN TONIGHT ALONG AND BEHIND THE FRONT WHICH SHOULD BE DRAPED ACROSS THE I-35 CORRIDOR BY SUNRISE. HAVE ALSO TRIMMED THE SW COUNTIES OFF TORNADO WATCH 125 WITH ADDITIONAL CONVECTIVE DEVELOPMENT APPEARING UNLIKELY THROUGH MIDNIGHT. TR.92 && .PREV DISCUSSION... /ISSUED 855 PM CDT MON MAR 17 2008/ AVIATION... 855 PM BACKING OFF ON THE THUNDER AND RAIN THIS EVENING FOR THE TAF SITES. NEWEST RUC INDICATES THAT THE WEAKENING PRECIP ACROSS THE AREA WILL CONTINUE TO WEAKEN AND HEAVY RAIN WILL NOT GET GOING UNTIL AFTER MIDNIGHT. 00Z NAM JUST COMING IN BUT HINTS AT THE SAME OUTCOME. THERE WILL STILL BE SOME SHOWERS IN THE VICINITY THIS EVENING. 84 UPDATE... 600 PM UPDATING TO INCLUDE TORNADO WATCH IN THE EAST. WATCHING STORMS EXPLODE IN LOW LEVEL CONFLUENCE ZONE OVER NORTHEASTERN COUNTIES AND THESE STORMS ARE IMMERSED WITHIN FAVORABLE ENVIRONMENT FOR LOW LEVEL ROTATION. WARM FRONT IS IN THE PARIS VICINITY ATTM WHICH WILL ENHANCE TORNADO THREAT. WATCH DOES NOT INCLUDE THE IMMEDIATE METROPLEX AREA...BUT WILL NOT HESITATE TO EXPAND IT WESTWARD BASED ON RADAR TRENDS DURING THE NEXT COUPLE HOURS...BUT THINKING IS TOR THREAT WILL BE JUST EAST THROUGH THE EVENING HOURS. TR.92 PREV DISCUSSION... /ISSUED 545 PM CDT MON MAR 17 2008/ AVIATION... 545 PM THIS TAF PACKAGE WILL CONTINUE WITH PREVIOUS TRENDS. EXPECT PRECIP TO CONTINUE TO INCREASE WITH METROPLEX AIFPORTS SEEING SHOWERS WITH EMBEDDED THUNDERSTORMS BY MID-LATE EVENING CONTINUING OVERNIGHT. CEILINGS WILL CONTINUE TO DECREASE THIS EVENING AND EXPECT MVFR CIGS BY LATE EVENING WITH A POSSIBLE DIP INTO IFR RANGE DEPENDING ON PRECIP. FRONT SHOULD PASS METROPLEX JUST AFTER SUNRISE TUESDAY BUT PRECIP WILL CONTINUE LIKELY THROUGH MIDDAY. 84 DISCUSSION... 242 PM A LINE OF SHOWERS AND THUNDERSTORMS CONTINUES TO DEVELOP ALONG A DRY LINE WHICH STRETCHED FROM ALTUS TO SWEETWATER TO NEAR FORT STOCKTON. A WARM FRONT RAN ROUGHLY ALONG A LINE FROM ALTUS TO ARDMORE TO PARIS. WATER VAPOR IMAGERY SHOWS A POTENT UPPER LOW SPINNING OVER ARIZONA. THIS FEATURE IS FORECAST TO DIP SOUTHEAST INTO NORTHERN MEXICO BEFORE MOVING ACROSS TEXAS TOMORROW. AS THIS OCCURS...LARGE SCALE ASCENT WILL INCREASE AND SHOWERS AND THUNDERSTORMS WILL EXPAND IN COVERAGE. ATMOSPHERE OVER NORTH TEXAS REMAINS CAPPED BUT IS IN THE PROCESS OF ERODING. A 19Z SOUNDING WILL CONFIRM THIS. VERY MOIST GULF AIR HAS ADVECTED ACROSS MUCH OF THE CWA WITH DEWPOINTS COMMONLY IN THE 60S. SKIES ARE CLEARING ALONG AND AHEAD OF THE DRY LINE ALLOWING FOR DECENT INSOLATION. RESULTANT SBCAPES OF AT LEAST 2000 J/KG AND AMPLE SHEAR WILL FOSTER DISCRETE SUPERCELLS ALONG THE DRY LINE WITH THE POTENTIAL TO PRODUCE LARGE HAIL...DAMAGING WINDS...AND TORNADOES. A SEVERE THUNDERSTORM WATCH IS ALREADY IN EFFECT FOR EXTREME WESTERN PORTIONS OF NORTH TEXAS. STORM MODE WILL TRANSITION TO A LINEAR MCS AS THE COLD FRONT CATCHES UP WITH THE DRY LINE LATE TONIGHT. EXPECT WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS NORTH TEXAS OVERNIGHT AND INTO TOMORROW WITH VERY MOIST AIR IN PLACE. GREATEST THREAT WILL THEN BECOME FLASH FLOODING WITH HPC FORECASTING 24 HR QPF AMOUNTS AS HIGH AS 5 INCHES ALONG THE RED RIVER. MOST NORTH TEXANS CAN EXPECT RAINFALL AMOUNTS BETWEEN 2 AND 4 INCHES BEFORE ALL IS SAID AND DONE. A FLASH FLOOD WATCH REMAINS IN EFFECT FROM 00Z THIS EVENING THROUGH WEDNESDAY MORNING FOR MUCH OF THE AREA. RAIN PROCESSES WILL BEGIN TO SHUT DOWN FROM WEST TO EAST WEDNESDAY MORNING AS THE UPPER LOW MOVES OFF TO THE NORTHEAST. SOME WRAP- AROUND PRECIP IS LIKELY ACROSS THE NORTHERN COUNTIES. UPPER LEVEL PATTERNS FLATTENS OUT FOR THE WEDNESDAY THROUGH FRIDAY TIME FRAME WITH HIGH TEMPERATURES WARMING INTO THE 70S THURSDAY AND FRIDAY. THE NEXT CHANCE FOR RAIN FOR NORTH TEXAS WILL OCCUR OVER THE WEEKEND AS A WEAK SHORTWAVE PASSES BY IN WNW FLOW ALOFT. SH/13 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 65 65 43 66 41 / 100 100 90 5 0 WACO, TX 66 66 46 68 42 / 100 100 80 0 0 PARIS, TX 66 66 44 59 38 / 100 100 100 10 0 DENTON, TX 63 63 42 64 39 / 100 100 80 5 0 MCKINNEY, TX 65 65 45 64 37 / 100 100 90 5 0 DALLAS, TX 65 65 44 67 45 / 100 100 90 5 0 TERRELL, TX 66 66 42 64 40 / 100 100 90 5 0 CORSICANA, TX 67 67 44 67 41 / 100 100 90 5 0 TEMPLE, TX 66 66 44 71 41 / 100 100 80 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR THE FOLLOWING ZONES: TXZ092>095-103>107-118>123-130>135-141>148-156>162-174-175. FLASH FLOOD WATCH UNTIL 1 AM CDT TUESDAY FOR THE FOLLOWING ZONES: TXZ102-117. && $$ tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 855 PM CDT MON MAR 17 2008 .AVIATION... 855 PM BACKING OFF ON THE THUNDER AND RAIN THIS EVENING FOR THE TAF SITES. NEWEST RUC INDICATES THAT THE WEAKENING PRECIP ACROSS THE AREA WILL CONTINUE TO WEAKEN AND HEAVY RAIN WILL NOT GET GOING UNTIL AFTER MIDNIGHT. 00Z NAM JUST COMING IN BUT HINTS AT THE SAME OUTCOME. THERE WILL STILL BE SOME SHOWERS IN THE VICINITY THIS EVENING. 84 && .UPDATE... 600 PM UPDATING TO INCLUDE TORNADO WATCH IN THE EAST. WATCHING STORMS EXPLODE IN LOW LEVEL CONFLUENCE ZONE OVER NORTHEASTERN COUNTIES AND THESE STORMS ARE IMMERSED WITHIN FAVORABLE ENVIRONMENT FOR LOW LEVEL ROTATION. WARM FRONT IS IN THE PARIS VICINITY ATTM WHICH WILL ENHANCE TORNADO THREAT. WATCH DOES NOT INCLUDE THE IMMEDIATE METROPLEX AREA...BUT WILL NOT HESITATE TO EXPAND IT WESTWARD BASED ON RADAR TRENDS DURING THE NEXT COUPLE HOURS...BUT THINKING IS TOR THREAT WILL BE JUST EAST THROUGH THE EVENING HOURS. TR.92 && .PREV DISCUSSION... /ISSUED 545 PM CDT MON MAR 17 2008/ AVIATION... 545 PM THIS TAF PACKAGE WILL CONTINUE WITH PREVIOUS TRENDS. EXPECT PRECIP TO CONTINUE TO INCREASE WITH METROPLEX AIFPORTS SEEING SHOWERS WITH EMBEDDED THUNDERSTORMS BY MID-LATE EVENING CONTINUING OVERNIGHT. CEILINGS WILL CONTINUE TO DECREASE THIS EVENING AND EXPECT MVFR CIGS BY LATE EVENING WITH A POSSIBLE DIP INTO IFR RANGE DEPENDING ON PRECIP. FRONT SHOULD PASS METROPLEX JUST AFTER SUNRISE TUESDAY BUT PRECIP WILL CONTINUE LIKELY THROUGH MIDDAY. 84 DISCUSSION... 242 PM A LINE OF SHOWERS AND THUNDERSTORMS CONTINUES TO DEVELOP ALONG A DRY LINE WHICH STRETCHED FROM ALTUS TO SWEETWATER TO NEAR FORT STOCKTON. A WARM FRONT RAN ROUGHLY ALONG A LINE FROM ALTUS TO ARDMORE TO PARIS. WATER VAPOR IMAGERY SHOWS A POTENT UPPER LOW SPINNING OVER ARIZONA. THIS FEATURE IS FORECAST TO DIP SOUTHEAST INTO NORTHERN MEXICO BEFORE MOVING ACROSS TEXAS TOMORROW. AS THIS OCCURS...LARGE SCALE ASCENT WILL INCREASE AND SHOWERS AND THUNDERSTORMS WILL EXPAND IN COVERAGE. ATMOSPHERE OVER NORTH TEXAS REMAINS CAPPED BUT IS IN THE PROCESS OF ERODING. A 19Z SOUNDING WILL CONFIRM THIS. VERY MOIST GULF AIR HAS ADVECTED ACROSS MUCH OF THE CWA WITH DEWPOINTS COMMONLY IN THE 60S. SKIES ARE CLEARING ALONG AND AHEAD OF THE DRY LINE ALLOWING FOR DECENT INSOLATION. RESULTANT SBCAPES OF AT LEAST 2000 J/KG AND AMPLE SHEAR WILL FOSTER DISCRETE SUPERCELLS ALONG THE DRY LINE WITH THE POTENTIAL TO PRODUCE LARGE HAIL...DAMAGING WINDS...AND TORNADOES. A SEVERE THUNDERSTORM WATCH IS ALREADY IN EFFECT FOR EXTREME WESTERN PORTIONS OF NORTH TEXAS. STORM MODE WILL TRANSITION TO A LINEAR MCS AS THE COLD FRONT CATCHES UP WITH THE DRY LINE LATE TONIGHT. EXPECT WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS NORTH TEXAS OVERNIGHT AND INTO TOMORROW WITH VERY MOIST AIR IN PLACE. GREATEST THREAT WILL THEN BECOME FLASH FLOODING WITH HPC FORECASTING 24 HR QPF AMOUNTS AS HIGH AS 5 INCHES ALONG THE RED RIVER. MOST NORTH TEXANS CAN EXPECT RAINFALL AMOUNTS BETWEEN 2 AND 4 INCHES BEFORE ALL IS SAID AND DONE. A FLASH FLOOD WATCH REMAINS IN EFFECT FROM 00Z THIS EVENING THROUGH WEDNESDAY MORNING FOR MUCH OF THE AREA. RAIN PROCESSES WILL BEGIN TO SHUT DOWN FROM WEST TO EAST WEDNESDAY MORNING AS THE UPPER LOW MOVES OFF TO THE NORTHEAST. SOME WRAP- AROUND PRECIP IS LIKELY ACROSS THE NORTHERN COUNTIES. UPPER LEVEL PATTERNS FLATTENS OUT FOR THE WEDNESDAY THROUGH FRIDAY TIME FRAME WITH HIGH TEMPERATURES WARMING INTO THE 70S THURSDAY AND FRIDAY. THE NEXT CHANCE FOR RAIN FOR NORTH TEXAS WILL OCCUR OVER THE WEEKEND AS A WEAK SHORTWAVE PASSES BY IN WNW FLOW ALOFT. SH/13 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 60 63 43 66 41 / 100 100 90 5 0 WACO, TX 63 65 46 68 42 / 100 100 80 0 0 PARIS, TX 63 65 44 59 38 / 100 100 100 10 0 DENTON, TX 57 59 42 64 39 / 100 100 80 5 0 MCKINNEY, TX 61 64 45 64 37 / 100 100 90 5 0 DALLAS, TX 61 65 44 67 45 / 100 100 90 5 0 TERRELL, TX 64 65 42 64 40 / 100 100 90 5 0 CORSICANA, TX 64 65 44 67 41 / 100 100 90 5 0 TEMPLE, TX 63 66 44 71 41 / 100 100 80 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR THE FOLLOWING ZONES: TXZ092>095-103>107-118>123-130>135-141>148-156>162-174-175. && $$ 99/99 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LUBBOCK TX 1123 AM CDT MON MAR 17 2008 .UPDATE... COMPLEX SCENARIO ATTM ACROSS THE FCST AREA. 12Z WRF-NAM AND TO A LESSER DEGREE THE 15Z RUC SEEM TO HAVE THE BEST HANDLE ON EVOLUTION OF SFC FEATURES THROUGH THE DAY. SFC TROUGH NEAR A FLUVANNA TO PADUCAH TO CHILDRESS LINE AT 16Z WITH SOUTH WINDS AND WARM TEMPS TO THE EAST OF THE TROUGH AND NW WINDS AND RELATIVELY COOL BUT FAIRLY MOIST CONDITIONS TO THE WEST. A COLD FRONT IS POISED NOT TOO FAR NORTH INTO THE TX PANHANDLE. MODELS STILL INSIST IN SOME PRESSURE FALLS INDUCING BACKING FLOW ACROSS THE SWRN ZONES WITH DRIER AND WARMER CONDITIONS THERE BY MID AFTERNOON. UPSTREAM WINDS AT RUIDOSO...GUADALUPE PASS AND CARLSBAD SUGGEST THIS MAY YET OCCUR. SERN PANHANDLE HOWEVER MAY REMAIN SOCKED IN BEHIND LOW CLOUDS AND A SURGE SWD OF COOLER AIR AND NLY WINDS. WILL ALSO HAVE TO WATCH HOW FAR S AND W STRATUS REMAINS OVER THE SCNTL AND SWRN PANHANDLE AND EFFECT ON TEMPS THERE. HAVE MADE SOME MAJOR CHANGES TO THE FCST BASED UPON THESE TRENDS. 12Z MODEL RUNS CONTINUING TREND OF 06Z RUNS WITH A SLOWER AND FURTHER NORTH HANDLING OF THE CLOSED LOWS EJECTION TUESDAY. MAY HAVE TO INCREASE POPS SOME LATER TONIGHT AND TUESDAY...AS WELL AS PULL POPS BACK TO THE NW. WILL ADDRESS THAT WITH THE FCST PACKAGE THIS AFTN. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 56 32 55 24 68 / 0 10 10 0 0 TULIA 60 34 56 28 67 / 10 10 10 0 0 PLAINVIEW 64 36 57 27 67 / 10 20 10 0 0 LEVELLAND 67 37 58 27 71 / 10 20 10 0 0 LUBBOCK 69 38 58 29 69 / 10 20 20 0 0 DENVER CITY 67 38 59 30 69 / 0 20 20 0 0 BROWNFIELD 70 40 58 29 70 / 10 20 20 0 0 CHILDRESS 66 40 55 36 70 / 10 30 20 10 0 SPUR 75 43 59 30 70 / 10 30 20 10 0 ASPERMONT 79 49 55 31 71 / 10 30 30 10 0 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 412 AM EDT WED MAR 19 2008 .SHORT TERM... DEEP SRN STREAM SW TROUGH FINALLY EJECTING NEWD. BACKING MID LVL FLW AND TIGHT LL THERMAL GRADIENT LEADING TO EXPANDING AREA OF LT-MOD RAIN OVR SERN HALF OF CWA W/HEAVIER FNTL RAIN BAND NOW CLIPPING SE CORNER OF CWA. TRIMMED FLOOD WATCH FM EARLIER UPDATE MAY NOW ACTUALLY PAN OUT ALG A MARION...OTTAWA LINE SOUTH AND IN LIGHT OF SHRT TERM RUC SOLUTION WILL REMAIN IN PLACE THROUGH 12Z AS DRIVING MID LVL BAROCLINIC ZONE WORKS SLOWLY EWD. AFT THAT...HEAVIEST RAIN WILL SHIFT EWD INTO CNTRL/SRN OH CORRESPONDING TO BEST LL MSTR TRANSPORT W/ELONGATED MID LVL DEFORMATION ZONE HOLDING SE HALF THROUGH EARLY AFTN BFR BREAKING DOWN IN ASSOCN/W UPR TROUGH ACCELERATING EWD. LL CAA MAY STILL LEAD TO A MIX OF SNOW ON TAIL END OF PRECIP BUT W/SKIN TEMPS REMAINING WELL ABV FREEZING ACCUMULATIONS INSIGNIFICANT. MEANWHILE POST FNTL AIRMASS CONTS TO DRY NW AND WILL SPREAD SEWD THROUGH THE DAY W/EVENTUAL CLEARING LT AFTERNOON NW THROUGH EVENING SE AND GIVEN EXTRAPOLATION OF BACK EDGE TO PCPN SHIELD WILL DROP MENTION ALTOGETHER FAR NW. OTHERWISE WILL HOLD CLOSE TO GOING TEMPS FOR THE MOST PART GIVEN INTERVENTION HAS CAUSED MORE HARM THEN GOOD LAST TWO DAYS. && .LONG TERM... NEGATIVE HEIGHT ANOMALY IN THE GULF OF ALASKA THROUGH THE PERIOD WILL RESULT IN AN ACTIVE PATTERN DOWNSTREAM...WITH ONE DISTURBANCE POSSIBLY RESULTING IS SOME ACCUMULATING SNOW FRI INTO EARLY SAT AND ANOTHER SYSTEM BY MON NIGHT/TUE. THIS PATTERN DOES FAVOR OVERALL UPPER LEVEL TROUGHING IN THE EASTERN US WHICH WILL LIKELY RESULT IN BELOW NORMAL TEMPERATURES THROUGH THE MIDDLE OF NEXT WEEK. THU NIGHT - SAT AM: THE MAIN CONCERN CONTINUES TO BE THE PLACEMENT OF BAROCLINIC ZONE AND THE EVENTUAL TRACK OF A SFC LOW PROGGED TO TRACK ESE ALONG IT LATE THU NIGHT INTO FRI/FRI EVE. A SHRTWV WILL EJECT INTO THE CENTRAL/NORTHERN PLAINS AND INDUCE CYCLOGENESIS THU NIGHT NEAR/JUST SOUTH OF THE OMAHA AREA. THIS RELATIVELY WEAK SFC REFLECTION WILL THEN TRACK EAST INTO NORTHERN OR CENTRAL IN BY EARLY FRI EVE. FOLLOWED CLOSE TO PREVIOUS FCST WHICH MATCHED UP WELL WITH THE FARTHER NORTH 00Z OPERATIONAL GFS...NAM...AND SREF. HOWEVER...THE LATEST ECMWF AND GEM RUN ARE A LITTLE FARTHER SOUTH WITH BOUNDARY AND ACCUMULATING SNOW. SYSTEM IN QUESTION IS STILL OFFSHORE SO EXPECT DETAILS TO BECOME CLEARER WITH BETTER SAMPLING AS SHRTWV SLIDES INTO THE PAC NW BY WED EVE. TOP DOWN METHOD FROM GFS/NAM SOUNDINGS AND PROGGED PARTIAL THICKNESSES INDICATE ALL SNOW JUST NORTH OF THE 850H LOW TRACK AND RAIN SOUTH. AS FOR INITIAL THOUGHTS ON TIMING...THINK BAND OF PRECIP BREAKS OUT ACROSS E IA...N IL...AND S WI THU EVE AND TRACKS EAST INTO SRN MI AND POSSIBLY FAR NRN IN BY LATE THU NIGHT INTO FRI AM. THIS INITIAL BATCH OF PRECIP WILL DEVELOP IN RESPONSE TO THETA-E ADV WITH LL CONVERGENCE AT NOSE OF EXPECTED 35-50KT LL JET. ALSO...THE GFS AND NAM ARE REMAINING CONSISTENT IN SHOWING ROBUST FRONTOGENESIS MAINLY IN THE 850-700H LAYER WITH POTENTIAL NARROW BAND OF ACCUMULATING SNOW. EVEN IF BAND ASSOCIATED WITH LL FORCING ENDS UP JUST NORTH OF CWA THU NIGHT/FRI AM...STILL THINK CWA WILL GET INTO SOME RAIN/SNOW FRI AFTN/EVE WITH LARGE SCALE ASCENT PROVIDED BY SHRTWV AND ITS ASSOCIATED DEEPER MOISTURE/OMEGA. AS A RESULT...DECIDED TO CONTINUE WITH LIKELY SN POPS ALONG/NORTH OF ROUTE 6 06-18Z FRI AND CHC POPS FOR MIX SOUTH. AND CONTINUED WITH LIKELY POPS FRI AFTN EVERYWHERE FOR RAIN AND SNOW NORTH...AND ALL RAIN SOUTH. SOME LIGHT SNOW...POSSIBLY MIXED WITH RN IN THE EVE...WILL CONTINUE FRI NIGHT INTO SAT AM. KEPT WITH CHC POPS FOR THIS TIMEFRAME WITH SUBSEQUENT SHIFTS PROBABLY NEEDING TO BUMP POPS INTO LIKELY CATEGORY FOR AT LEAST FRI EVE. FIRST GUESS FOR TOTAL SNOW ACCUMULATION IN THE GRIDS IS 2-4 INCHES ALONG/NORTH OF ROUTE 6...AROUND AN INCH IN THE CENTRAL CWA...AND AN INCH OR LESS FAR SOUTH. SAT-TUE: SEVERAL WEAK DISTURBANCES IN NORTHWEST FLOW MAY BRING SOME VERY LIGHT PRECIP INTO THE REGION DURING THE SATURDAY THROUGH MONDAY TIMEFRAME. HOWEVER...WILL KEEP WITH DRY FCST AS TIMING THESE QUICK MOVING WAVES IS NEARLY IMPOSSIBLE THIS FAR OUT AND THAT ANY SNOW WILL BE BRIEF/LIGHT DUE TO THERE BEING LITTLE IF ANY MOISTURE TO WORK WITH. THE ONLY EXCEPTION WILL BE SNOW CHCS SAT AM WITH TROUGH AXIS SWINGING THROUGH. THE ECMWF AND GEM CONTINUE TO HINT AT A STRONG WAVE ROUNDING THE BASE OF THE TROUGH WITH A POTENTIAL WINTER STORM AFFECTING THE EASTERN SEABOARD. THIS WILL REINFORCE TROUGH IN PLACE AND KEEP TEMPERATURES WELL BELOW NORMAL THROUGH THE WEEKEND INTO THE FIRST PART OF NEXT WEEK. KEPT LOW CHC POPS IN FOR LATE MON NIGHT INTO TUE AS 00Z GUIDANCE REMAINS CONSISTENT IN DROPPING A CLIPPER-LIKE SYSTEM INTO THE GREAT LAKES. && .AVIATION/UPDATE... WIDESPREAD IFR/MVFR XPCD TO CONT THROUGH MID MORNING COINCIDENT W/EXPANDING AREA OF LT-MOD RAIN INADV OF EJECTING DEEP SRN STREAM SW TROUGH. REGIONAL VWP/PROFILERS SHOWING BACKING MID LVL FLW AHD OF MID LVL TROUGH AND W/DECAYED CONVECTION THROUGH THE OH RIVER VALLEY FOR THE TIME BEING BTR MSTR TRANSPORT INVOF OF TIGHT MID LVL BAROCLINIC ZONE. HWVR BEST COMBINATION OF MSTR FLUX CVRG AND FORCED ASCENT STILL SOUTH OF MOST 00Z MODEL DEPICTIONS AND TRIMMED NRN PORTION OF FLOOD WATCH FURTHER TO ACCOUNT FOR UPSTREAM EXTRAPOLATION OF HEAVIER RAIN BANDS THROUGH THIS MORNING. IMPROVING CONDS LT THIS AFTN AS TROUGH ACCELERATES EWD AND MORE SIG LL DRYING ENSUES. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR INZ026-027-032>034. MI...NONE. OH...FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR OHZ016-024-025. LM...NONE. && $$ SHORT TERM...HOLSTEN LONG TERM...STEINWEDEL AVIATION/UPDATE...HOLSTEN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 222 AM MDT WED MAR 19 2008 .DISCUSSION... 222 AM MDT WED MAR 19 2008 FORECAST PROBLEMS WILL BE HIGH TEMPERATURES/WINDS/FIRE WEATHER CONCERNS TODAY...TEDIOUS TEMPERATURE/WIND FORECAST THURSDAY...AND HOW MUCH TO COOL DOWN FRIDAY...AND CHANCES OF PRECIPITATION THURSDAY NIGHT AND AT THE BEGINNING OF THE WEEKEND. SATELLITE SHOWING A PROGRESSIVE FLOW FROM THE CENTRAL PACIFIC THROUGH THE CONTINENTAL UNITED STATES. SOUTHERN PLAINS LOW LOOKING LIKE IT IS BEGINNING TO PUSH EAST. FLOW SLOWS UP AND IS BLOCKY IN THE CENTRAL ATLANTIC. AT JET LEVEL...INITIALLY MODELS DID WELL WITH JET POSITION AND STRENGTH...ESPECIALLY WITH THE JET TO OUR NORTH. THE NAM AND UKMET WERE SLIGHTLY BETTER THAN THE GFS. AT 06Z...THE MODELS WERE A LITTLE TOO FAR SOUTH WITH THE JET POSITION. AT MID LEVELS...MODELS ARE REASONABLY INTIALIZED AND SIMILAR. ALL OF THEM ARE CATCHING NORTHERN STREAM SHORTWAVE TROUGH WELL. THEY DO DIFFER ON THE SOUTHERN PLAINS LOW BUT DIFFERENCES DO NOT APPEAR SIGNIFICANT AT THIS TIME. THE GFS DOES LOOK TO HAVE TO BE TOO MOIST. AT LOW LEVELS...THE NAM AND RUC WERE DOING THE BEST WITH THE WIND FIELD. MODELS WERE HAVING DIFFICULTY WITH THE COLD POOL TO OUR EAST AND TO A LESSER EXTENT TO OUR NORTH. MODELD DID NOT HAVE THE EASTERN COLD POOL FAR ENOUGH SOUTH AND EAST. OVERALL THE GFS WAS DOING SLIGHTLY BETTER THAN THE UKMET AND ECMWF. WILL BE GOING WITH A BLEND OF THE MODELS WITH A TREND TOWARD THE WARMER...DRIER...AND WINDIER OUTPUT. TODAY/TONIGHT...THE MAIN JET WILL REMAIN TO THE NORTH OF THE AREA THROUGH THE DAY WITH FORECAST AREA UNDER JET SUBSIDENCE. AREA LOOKS TO HAVE PLENTY OF SUN. MAY HAVE AFTERNOON CUMULUS BUILD UP AGAIN BUT IT LOOKS A LITTLE LESS THAN YESTERDAY. SNOW FIELD WAS A NON ISSUE YESTERDAY WITH THE TEMPERATURES WITH GUIDANCE AND FORECAST BEING TOO COOL. THIS HAS BEEN THE TREND OF THE MAV/GFS LATELY. USING THE TEMPERATURE CHANGE FROM YESTERDAY...DIURNAL RANGE...AND BIASES FROM THE 2 METER AND 850 MB...YIELDED TEMPERATURES IN THE LOWER AND MIDDLE 60S WHICH IS WARMER THAN THE PREVIOUS FORECAST. BASED ON TRAJECTORY OF THE SYSTEM TO OUR NORTH...DRY LOW LEVEL AIR MASS...AND SUBSIDENCE...EXPECT THE WINDS OVER MOST OF THE AREA TO BE BREEZY AGAIN. ANOTHER PROBLEM WITH THIS IS LOW DEWPOINTS EXPECTED. DEWPOINTS NEAR WESTERN END OF OUR FORECAST AREA AND UPSTREAM RANGE FROM THE MIDDLE TEENS TO NEAR 20 AND THIS IS IN THE MIDDLE OF THE NIGHT. AREA SOUNDINGS WOULD SHOW THAT DEWPOINTS WILL HAVE POTENTIAL TO TANK ONCE MIXING OCCURS. MOST MODEL OUTPUT IS WAY TOO HIGH ON MOISTURE. USED THE NGM AS A FIRST GUESS SINCE IT WAS THE LOWEST...AND THEN MODIFIED. WIND WIND WILL BE THE WILD CARD AND WILL BE CLOSE. MAY NEED TO ISSUE A WARNING. WIND FIELD IS VERY LIGHT TONIGHT...ESPECIALLY IN THE EASTERN HALF. THERE IS A TENDENCY TOWARD UPSLOPE BUT SINCE SPEEDS ARE NOT THAT HIGH...DO NOT BUY THE HIGHER DEWPOINTS. WITH LITTLE CLOUD COVER... BELIEVE THAT LOWS COULD DROP WELL BELOW GUIDANCE. TRENDED MINS... ESPECIALLY IN THE EAST...TO THAT DIRECTION. THURSDAY/THURSDAY NIGHT...MODELS ARE IN CLOSER AGREEMENT TO THE JET POSITION THAN THEY WERE YESTERDAY. ALTHOUGH THERE IS SLIGHT DIFFERENCE BY THE END OF THE DAY. THE UKMET AND NAM ARE FURTHER NORTH WITH THE AXIS. THE NAM BRINGS IN A BETTER RIGHT REAR QUADRANT IN THE AFTERNOON THAN THE UKMET WHICH KEEPS US IN MUCH LESS LIFT. THE GFS AGAIN IS SLIGHTLY FURTHER SOUTH. HOWEVER...IT DOES NOT BRING THE AXIS OVER THE AREA UNTIL THE AFTERNOON. ALL THE MODELS BRING THE RIGHT REAR QUADRANT ACROSS THE FORECAST IN THE 00Z TO 06Z TIME FRAME. MAIN SYSTEM AND STRONGEST LIFT REMAIN WELL NORTH OVER THE NORTH CENTRAL PORTION OF THE COUNTRY. HOWEVER...THE MODELS DO SWING A DECENT SHORTWAVE TROUGH THROUGH THE AREA DURING THE EVENING. THEN SUBSIDENCE AND AN EXTREMELY DRY AIR MASS ALOFT QUICKLY MOVE IN AFTER 06Z. SO WHATEVER PRECIPITATION FALLS WILL BE DONE BY 06Z. POINT SOUNDINGS WOULD INDICATE THAT LOW LEVELS WILL BE DRY. CONSIDERING THAT THE FRONT AND WESTERLY SURFACE WINDS WILL PRECEDE UPPER LIFT...WOULD AGREE WITH THAT ASSESSMENT. SINCE SYSTEM WILL GO QUICKLY THROUGH...DO NOT BELIEVE THERE WILL BE TIME FOR THE MOISTURE TO SATURATE DOWN. THE TENDENCY WITH THESE FAST WEST TO NORTHWEST SHORTWAVES HAS BEEN TO OVERPRODUCE PRECIPITATION. AM LEANING TOWARD JUST HAVING EVENING SPRINKLES AT THIS TIME. HIGH TEMPERATURE FORECAST WILL BE TRICKY. A LOT WILL DEPEND ON HOW FAST WEAK BOUNDARY/EASTERLY WINDS MIX OUT AND PUSH TO THE EAST. GIVEN THE FLOW ALOFT AND GOOD MIXING EXPECTED...THINK THAT THE BOUNDARY WILL MOVE EAST RAPIDLY. HOWEVER...CLOUDS INCREASE AND FRONT APPROACHES IN THE AFTERNOON. USING DIFFERENT TEMPERATURE METHODS POINTED TO TEMPERATURES BEING NEAR TO SLIGHTLY ABOVE 70 OVER MOST OF THE AREA. IF HAVE LESS CLOUDS AND SLOWER FRONT...WILL BE MUCH WARMER. MODELS...ESPECIALLY THE NAM...ALSO BRING UP THE WINDS TO NEAR OR SLIGHTLY ABOVE 20 KNOTS. NOT THE RIGHT TIME OF DAY YOU WOULD EXPECT TO GET STRONG WINDS. MODELS ARE INDICATING STRONG SUBSIDENCE AND MAY BE POSSIBLE AND CONSIDERING A FAVORABLE TRACK OF THE UPPER SYSTEM TO BRING IN STRONGER WINDS...THIS DOES SEEM REASONABLE. WILL INCREASE WINDS FOR THE NIGHT WHICH WILL KEEP MINS MILD. FRIDAY/FRIDAY NIGHT...MAIN JET IS FURTHER SOUTH. HOWEVER...NAM AND GFS DEVELOP A SECONDARY AXIS THAT PUTS THE AREA...MOSTLY THE NORTHEAST HALF...IN SOME LIFT DURING THE AFTERNOON. HOWEVER THERE LOOKS TO BE PLENTY OF SUN...SPRING SUN...WITH DOWNSLOPE COMPONENT TO THE WINDS. MODELS HAVE BEEN TOO COOL IN THIS SETUP THIS MONTH AND WILL TEND TO GO TOWARD THE WARMER GUIDANCE. WILL ALSO PROBABLY KEEP THE WINDS UP CONSIDERING THAT MIXING AND SUBSIDENCE WILL CONTINUE. AREA STAYS UNDER THE ENTRANCE REGION OF THE JET THROUGH THE NIGHT AND A STRONG SHORTWAVE IS APPROACHING FROM THE NORTHWEST. POINT SOUNDINGS SHOW THAT THE LOW LEVELS ARE TOO DRY TO ALLOW MEASURABLE PRECIPITATION DURING THE NIGHT. WILL KEEP IT DRY BUT RAISE THE SILENT POPS. SATURDAY...MOISTURE AND FORCING COME TOGETHER DURING THE DAY. THE LAPSE RATES ARE THE BEST IN THE SOUTHWEST HALF. FORECAST HAS PRECIPITATION IN THERE AND WILL ONLY TWEEK IF NECESSARY. COOLER TEMPERATURES FOR SATURDAY LOOK FINE AT THIS TIME. THANKS TO ALL FOR COLLABORATION...IT WAS MUCH APPRECIATED. BULLER && .AVIATION... 1120 PM MDT TUE MAR 18 2008 FOR THE 06Z TAF CYCLE...VFR CONDITIONS WILL CONTINUE TO DOMINATE BOTH KGLD AND KMCK. AT KMCK...WINDS ARE NOW...AND WILL CONTINUE TO REMAIN CALM UNTIL ABOUT 17Z OR 18Z. AT KGLD WINDS ARE NOW FROM THE WEST AT 8 KTS. FOR BOTH KGLD AND KMCK...FROM ABOUT 18Z TO 23Z... WESTERLY AND NORTHWESTERLY WINDS WILL INCREASE TO THE 15 KT RANGE WITH SOME GUSTS IN THE 25 KT RANGE. AFTER 23Z...NORTHWESTERLY AND NORTHERLY WINDS WILL CALM TO THE 5 TO 10 KT RANGE. SKIES WILL REMAIN MOSTLY CLEAR OVERNIGHT AND THROUGH A GOOD PORTION OF THE DAY TOMORROW. BY 00Z...BKN HIGH LEVEL CLOUDS WILL MOVE OVER THE REGION. BLM && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ WFO GOODLAND ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 AM EDT WED MAR 19 2008 .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS STARTING TO SHOW SOME CHANGE IN THE PATTERN THANKS TO A BIT STRONGER ZONAL PACIFIC JET PUNCHING INTO THE PACIFIC NW. STILL...SPLIT FLOW EXISTS ACROSS THE EASTERN 2/3 OF NORTH AMERICA. IN THE NORTHERN STREAM...AN UPPER TROUGH STRETCHES FROM NE MANITOBA...INTO NW ONTARIO AND SW INTO SRN MN...WITH RIDGING AHEAD OF IT IN SE CANADA. IN THE SOUTHERN STREAM...AN UPPER TROUGH IS PRESENT OVER OK AND EAST TEXAS...WITH STRONG RIDGING DOWNSTREAM OVER THE SE U.S.. A STRONG SUBTROPICAL JET STILL EXISTS AHEAD OF SRN PLAINS TROUGH...WITH MOISTURE ON WATER VAPOR STREAMING FROM THE EAST PACIFIC INTO THE OHIO VALLEY. THIS UPPER MOISTURE...COMBINED WITH STRONG SOUTHERLY WINDS BRINGING ABNORMALLY HIGH AMOUNTS OF GULF OF MEXICO MOISTURE NORTHWARD (PRECIPITABLE WATER VALUES OF 200-300 PCT OF NORMAL) IS CONTRIBUTING TO THE ONGOING FLOODING SITUATION ACROSS THE OHIO VALLEY INTO MO/AR. MUCH QUIETER WEATHER OCCURRING OVER THE CWA BEING NORTH OF THE SUBTROPICAL JET AND WITH VERY LITTLE FORCING. HOWEVER...AFTER YESTERDAYS SYSTEM...PLENTY OF LOW LEVEL MOISTURE REMAINS AS EVIDENCED BY LOW CLOUDS ACROSS MUCH OF ERN WI INTO UPPER MI PER 11-3.9U SATELLITE LOOP AND SURFACE OBS. 00Z SOUNDINGS FROM GRB AND INL DEPICT THIS MOISTURE BY SATURATION BETWEEN 900-850MB (ALSO THE LOCATION OF THE FRONTAL INVERSION). WITH AN INVERTED-V LOOK TO THE SOUNDINGS BELOW 900MB AND THE GENERAL THIN LAYER OF SATURATION... VERY LITTLE IN THE WAY OF PCPN IS OCCURRING. SKIES HAVE NOW CLEARED ACROSS MUCH OF MN...THANKS TO DRIER AIR EVIDENT ON THE 00Z SOUNDINGS FROM BIS AND ABR. UPSTREAM TO OUR NW...AIRMASS IS NOT ALL THAT COLD WITH 850MB TEMPS OF -7C AT INL AND -6C AT CWPL. 850MB TEMPS FALL BELOW -10C IN NORTHERN MANITOBA...WITH READINGS OF -11C AT THE PAS AND -17C AT CHURCHILL. && .DISCUSSION... MAIN FORECAST CONCERN IS LAKE EFFECT CLOUDS/PCPN THROUGH SAT. TODAY...UPPER TROUGH AXIS OVER MN IS PROGGED TO SHIFT EASTWARD ACROSS UPPER MI DURING THE DAY AND ALMOST TO LAKE HURON BY 00Z. ALSO TO NOTE IS A SHRTWV ON THE NRN END OF THIS UPPER TROUGH IN NORTHERN MANITOBA...WHICH IS EXPECTED TO DROP DOWN TO NEAR LAKE SUPERIOR BY 00Z. ALTHOUGH DPVA WILL OCCUR WITH THE UPPER TROUGH MOVING IN...THE LACK OF ANY MOISTURE IN THE MID LEVELS (AS NOTED FROM INL...MPX AND GRB RAOBS) MEANS LITTLE IF ANY IMPACT FROM IT. THE MAIN ITEM EXPECTED WITH THE TROUGH IS TO ALLOW THE COLDER AIR OVER NORTHERN MANITOBA TO FILTER INTO THE CWA. BY 21Z...850MB TEMPS ARE PROGGED BTWN -9 AND -12C. BEFORE THIS COOLING ARRIVES...SKIES SHOULD MAKE AN ATTEMPT AT CLEARING THIS MORNING AS THE DRIER AIR OVER MN AND NW WI MOVES IN. CLOUDS WILL THEN REDEVELOP EITHER LATE THIS MORNING OR EARLY THIS AFTERNOON AS THE COLDER AIR MIXED WITH DAYTIME HEATING STEEPEN LOW LEVEL LAPSE RATES...ALONG WITH SURFACE DEWPOINTS REMAIN RELATIVELY HIGH (WHICH ARE ALSO AIDED BY MOISTENING OFF LAKE SUPERIOR). SOME DIURNAL -SHSN ARE EXPECTED TOO OUT OF THESE CLOUDS...PRIMARILY IN THE DOWNSLOPING NW FLOW AREAS. SOME LAKE EFFECT SNOW SHOWERS COULD ALSO DEVELOP LATE IN THE DAY AS SOLAR HEATING DIMINISHES AND THE COLDER AIR AROUND -12C MOVES IN. ACCUMULATION SHOULD BE LITTLE DUE TO LOW INVERSIONS...SMALL CLOUD DEPTHS AND THE STRONGER MARCH SUN MELTING SNOW. BECAUSE OF MORE SOLAR HEATING...AND THE BETTER MIXING WITH COLD ADVECTION...TEMPS TODAY SHOULD BE AT OR ABOVE YESTERDAYS READINGS. WARMEST TEMPS... NEAR 40...EXPECTED IN THE DOWNSLOPING NW FLOW AREA IN THE SOUTH CENTRAL U.P.. TONIGHT...SRN STREAM TROUGH OVER ERN TEXAS LIFTING NE TODAY IS SHOWN TO PHASE WITH THE NRN STREAM TROUGH DURING THIS PERIOD...OVER THE EASTERN GREAT LAKES. AS THIS PHASING OCCURS...EVEN COLDER AIR IS ADVECTED SOUTHWARD INTO THE AREA...WITH HELP FROM THE SHRTWV NEAR LAKE SUPERIOR AT 00Z CROSSING NEAR ANJ AROUND 06Z. 850MB TEMPS ARE PROGGED TO DROP TO -12 TO -14C...AND WITH WIND FLOW FROM THE NNW SHOULD ALLOW FOR LAKE EFFECT SNOW SHOWERS TO IMPACT MUCH OF THE NORTHERN AND EASTERN U.P.. STILL...INVERSIONS ARE ONLY PROGGED TO REACH AT 5000 FT...SO CANNOT IMAGINE LAKE EFFECT WILL GET GOING TOO STRONG. HOWEVER...ONE BIG POSITIVE FOR SNOW PRODUCTION IS THAT MUCH OF THE CLOUD DECK IS WITHIN THE DENDRITIC GROWTH ZONE...SO SNOW TO WATER RATIOS WILL BE ON THE HIGH SIDE...30 TO 1 OR HIGHER. THEREFORE...IF ANY BAND CAN SET UP FOR A FEW HOURS...AS OUR LOCAL WRF-ARW RUN DEPICTS IN LUCE COUNTY...A COUPLE OF INCHES ARE NOT OUT OF THE QUESTION. DAY SHIFT MAY NEED TO LOOK AT THIS MORE. LOW TEMPS WILL CERTAINLY BE COLDER THAN THE CURRENT READINGS THANKS TO THE COLDER AIRMASS MOVING IN. INLAND AREAS OF THE WESTERN U.P. COULD DROP DOWN INTO THE MID TEENS. WARMER TEMPS EXPECTED ELSEWHERE WITH FLOW OFF LAKE SUPERIOR. THURSDAY...PHASING TROUGH SHIFTS TO NEW ENGLAND BY 00Z THU...WHICH ALLOWS A SURFACE RIDGE TO BUILD INTO THE CWA (CURRENTLY IN NW MANITOBA). DRY AIR ASSOCIATED WITH THE SURFACE RIDGE...COMBINED WITH DAYTIME HEATING AND 850MB TEMPS RISING TO -8 TO -10C BY 21Z...WILL LIKELY DISRUPT THE LAKE EFFECT. HOWEVER INLAND AREAS SUCH AS IRON COUNTY MIGHT BE ABLE TO GENERATE SOME DIURNAL STRATOCU. VERY LITTLE CONCERN FOR PCPN COMING OUT OF THIS STRATOCU COMPARED TO TODAY DUE TO EVEN LOWER INVERSION HEIGHTS...ALONG WITH DRIER SURFACE DEWPOINTS MOVING IN. WOULD NOT BE SURPRISED TO SEE THE SPRING/SUMMER-TIME LOOK OF CLEARING OVER THE LAKE AND LAND AREAS NEAR THE SHORE THANKS TO LAKE BREEZES...AND MORE CLOUDS INLAND. ALTHOUGH 850MB TEMPS WARM THROUGH THE DAY...THE COLDER START OFF COMPARED TO TODAY SHOULD RESULT IN COLDER HIGHS...PROBABLY BY A FEW DEGREES AT LEAST. WARMEST TEMPS STILL EXPECTED IN THE SOUTH CENTRAL U.P. WHERE NW WINDS CONTINUE TO DOWNSLOPE. THU NIGHT AND FRI...MODELS OVER THE PAST FEW DAYS HAVE BEEN EXPERIENCING ISSUES WITH REGARDS TO A SHRTWV MOVING ACROSS THE CENTRAL PLAINS DURING THIS PERIOD. THE SYSTEM ORIGINATES FROM THE UPPER TROUGH CURRENTLY OFF THE PACIFIC NW. THE QUESTION IS AS THIS SHRTWV COMES OUT INTO THE CENTRAL PLAINS (PRIMARILY KS/NE/IA/MO AREA)...WILL IT BE A FLATTER OR HAVE MORE AMPLITUDE. THE 19/00Z AND 18/12Z ECMWF RUNS ARE THE FLATTEST OF THE BUNCH...WHICH ALLOWS THE HIGH PRESSURE RIDGE BUILDING INTO THE AREA THU TO REMAIN IN PLACE THRU FRI. THE UKMET IS THE MOST AMPLIFIED...AND IF IT WERE TO PAN OUT...POPS WOULD HAVE TO BE INTRODUCED ALONG THE WI BORDER FRI. HAVE FOLLOWED HPC PREFERENCE...WHICH IS THE COMPROMISE SOLUTIONS OF THE GFS/NAM. THESE SOLUTIONS RESULT IN BRINGING MORE CLOUD COVER INTO THE CWA THU NIGHT...MOSTLY IN THE FORM OF MID/HIGH CLOUDS. THUS...HAVE BOOSTED LOW TEMPS UP A BIT. THESE CLOUDS SHOULD SLOWLY EXIT THE CWA ON FRI AS THE SYSTEM PROGRESSES INTO CENTRAL ILLINOIS. GIVEN THE MORE CLOUD COVER ON FRI...ENDED UP KNOCKING DOWN HIGHS A FEW DEGREES...WHICH PROBABLY WOULD NEED TO BE LOWERED TOO BECAUSE OF NE WINDS AROUND THE HIGH PRESSURE AREA BRINGING COOL AIR DOWN OUT OF ONTARIO. ONLY OTHER ISSUE DURING THIS PERIOD IS LAKE EFFECT. FOLLOWED THE PREVIOUS FORECAST AND NAM/GFS 900/925MB RH FIELDS WHICH TAKE DISSIPATING CLOUDS BANDS OVER THE EASTERN CWA WESTWARD AS WINDS SWITCH TO THE NE. ANY WEAK SNOW SHOWERS AND CLOUDS SHOULD DISSIPATE DURING THE DAY FRI AS DRY AIR AND HEATING HELP MIX THEM OUT. FRI NIGHT AND SAT....AS THE SYSTEM IN CENTRAL ILLINOIS EXITS OFF TO THE EAST FRI NIGHT...ANOTHER AREA OF HIGH PRESSURE BEGINS BUILDING SOUTH OUT OF CENTRAL CANADA. THIS AREA OF HIGH PRESSURE WILL HELP TO REINFORCE NE WINDS OVER THE CWA. THE QUESTION DURING THIS PERIOD...WHICH AFFECTS MAINLY THE WEST HALF OF THE CWA...IS WHETHER OR NOT LAKE EFFECT CLOUDS CAN REFORM...AS INDICATED BY 925MB RH FIELDS OFF THE NAM/GFS. THE GFS/NAM 925MB TEMPS ARE AROUND -10C...WHICH IS PLENTY COLD ENOUGH TO GENERATE CLOUDS OFF THE LAKE. HOWEVER...THE AIR COMING ACROSS LAKE SUPERIOR MAY BE TOO DRY TO ALLOW FOR CLOUD GROWTH. FOR NOW...TOOK A MIDDLE OF THE ROAD APPROACH...INCREASING CLOUD COVER AND RAISING TEMPS UP OVER THE WEST HALF OF UPPER MI. IF THE NAM/GFS ARE CORRECT...SOME FLURRIES WOULD HAVE TO BE INTRODUCED TOO...PARTICULARLY IN UPSLOPE AREAS. ON SAT...A FEW SHRTWVS ARE PROGGED TO DROP SOUTH THROUGH THE NORTHERN PLAINS...BUT REMAINING FAR ENOUGH WEST TO PREVENT ANY PCPN HERE. ANY LAKE EFFECT CLOUDS SHOULD AGAIN DISSIPATE WITH HEATING. LOWERED HIGHS SLIGHTLY TO ACCOUNT FOR THE PERSISTENT NE FLOW. BEYOND SAT...NO CHANGES MADE. HOWEVER...THE 18/12Z AND 19/00Z ECMWF ARE SUGGESTING A BRIEF BOUT OF ARCTIC AIR CLIPPING THE CWA SUN NIGHT AND MON. 850MB TEMPS FALL TO -16 TO -18C BY 00Z TUE. IF THESE ARE CORRECT...HIGHS WILL NEED TO BE LOWERED. DRY AIRMASS ACCOMPANIES THIS COLD AIR...THEREFORE ANY LAKE EFFECT SHOULD BE WEAK. AWAY FROM THE CWA...IF THESE ECMWF RUNS ARE CORRECT...THERE COULD BE A LATE SEASON SNOWSTORM FOR THE MID-ATLANTIC AND NORTHEAST U.S. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... APPEARS NARROW BAND OF HIGHER SFC DWPTS SHOULD BE CROSSING THE KEWEENAW ATTM. SO...HAVE MAINTAINED A MENTION OF LIFR CIGS AND MVFR VIS IN -FZDZSN THRU ABOUT 07Z AT KCMX. THIS IS INLINE WITH A FEW OBS THAT REPORTED -DZ/FLURRIES UPSTREAM IN NE MN EARLIER IN THE NIGHT. OTHERWISE...SLIGHTLY DRIER AIR IS SPREADING OVER WRN LAKE SUPERIOR AND WILL MAKE INROADS INTO UPPER MI FROM THE NW DURING THE OVERNIGHT. SINCE IT`S NOT A STRONG PUSH OF DRIER AIR...ANTICIPATE CIGS REMAINING IN THE MVFR RANGE FOR THE BULK OF THE FCST PERIOD AT KCMX. SOME LAKE EFFECT -SHSN MAY DEVELOP IN THE EVENING AS AIRMASS BECOMES COLDER. AT KSAW...EXPECT MVFR CIGS TO DOMINATE THRU THE NIGHT INTO THE AFTN. THERE MAY BE A PERIOD LATE IN THE NIGHT/EARLY MORNING WHERE CLOUDS SCT OUT AS DRIER AIR AND DOWNSLOPING NW WINDS WORK TO BREAK UP CLOUD DECK. IF CLOUDS DO SCT OUT...DAYTIME HEATING SHOULD RESULT IN REDEVELOPMENT OF MVFR CIGS MID/LATE MORNING. CLOUDS SHOULD LIFT TO VFR IN THE AFTN. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NO GALES FORESEEN ANYTIME SOON. WINDS DO GET UP TO 30 KNOTS TODAY THROUGH THU AFTERNOON BEFORE DECREASING BECAUSE OF A TIGHT PRESSURE GRADIENT BETWEEN LOW PRESSURE EAST OF HERE AND A HIGH BUILDING INTO THE NORTHERN PLAINS. WITH COLD AIR TONIGHT AND STRONGER WINDS OVER THE EASTERN CWA...HEAVY FREEZING SPRAY WILL BRIEFLY BE POSSIBLE ACROSS THE CENTRAL AND EASTERN PARTS OF THE LAKE. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 2 AM TO 8 AM EDT THURSDAY FOR LSZ264-266-267. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...ROLFSON MARINE...GJM mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 130 AM EDT WED MAR 19 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .UPDATE... (ISSUED AT 1057 PM EDT) UPDATED FCST TO DROP MENTION OF ISOLD -SHSN/FZDZ LATE TONIGHT INTO THE EARLY MORNING FOR WRN UPPER MI AS DRIER AIR WILL BE SPREADING INTO THE AREA PER SATELLITE IMAGERY. BEFORE THEN...THERE STILL APPEARS TO BE SOME POTENTIAL FOR -FZDZ/FLURRIES FOR THE NEXT SEVERAL HOURS AS NARROW BAND OF SLIGHTLY HIGHER SFC DWPTS OVER EXTREME NE MN MOVES E AND UPSLOPES INTO WRN UPPER MI ON W TO NW WINDS. IN ADDITION...THERE HAVE BEEN A FEW OBS IN NE MN EARLIER THIS EVENING THAT INDICATED -DZ/-SN...AND KDLH RADAR HAS SHOWN SOME WEAK RETURNS. && .PREV DISCUSSION... (ISSUED AT 355 PM EDT) SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW ACRS NAMERICA WITH NRN BRANCH TROFFING DOMINATING THE UP GRT LKS. DISTURBANCE EMBEDDED WITHIN THIS FLOW THAT WAS RESPONSIBLE FOR THE SN THAT FELL EARLIER IN THE DAY IS NOW HEADING ENEWD THRU ERN UPR MI. ACCOMPANYING PCPN HAS PRETTY MUCH ENDED WITH ARRIVAL OF DRIER AIR ALF (IN THE LYR COLDER THAN -10C) THAT WAS SHOWN ON THE 12Z MPX SNDG. BUT PLENTY OF LO CLD REMAINS WITH AMPLE LLVL MSTR LINGERING. THE HIER LLVL DWPTS (GENERALLY 30 TO 35) AND IFR/MVFR CIGS EXTEND WWD THRU MOST OF MN TO NEAR REINFORCING COLD FNT NOW MOVING INTO NW MN. SOME LGT PCPN HAS BEEN OBSVD ALG AND JUST AHD OF THIS BNDRY. BUT DRIER AIR IS NOTED MOVING IN BEHIND THE COLD FNT. THE CORE OF THE COLDER AIR IS LOCATED A BIT FARTHER N...WITH 12Z H85 TEMP AT YQD DOWN TO -11C...VS -5C OBSVD AT INL. SHORT TERM DISCUSSION (TNGT AND WED)... MAIN FCST CONCERNS TNGT/TMRW ARE LGT PCPN CHCS/TYPE. NUMERICAL GUIDANCE HINTS COLD FNT NOW MOVING THRU MN WL MOVE INTO THE WRN ZNS ARND 06Z. WITH ABUNDANT LLVL MSTR NOTED AHEAD OF THIS BNDRY...MAINTAINED QUITE A BIT OF CLD COVER INTO THE OVERNGT AS WELL AS SOME PTCHY -DZ/-FZDZ/-SN ACRS MAINLY THE WRN ZNS WHERE LGT WLY FLOW WL UPSLOPE. ALSO INTRODUCED SOME LO CHC POPS FOR SIMILAR PCPN TYPE OVER THE ERN ZNS DOWNSTREAM OF LK SUP LATE TNGT WITH BETTER LLVL CNVGC ASSOCIATED WITH THE ARRIVAL OF THIS BNDRY. BUT INFLUX OF DRIER AIR LATE TNGT WL AT LEAST END THE POTENTIAL FOR -FZDZ OVER THE W AND BEGIN TO BREAK UP THE PERSISTENT CLD COVER IN THE DOWNSLOPE AREAS. IN ANY EVENT...LIMITED MOISTURE DEPTH AND MODEST CHILL (TEMPS WITHIN THE MOIST LYR FCST TO BE HIER THAN -10C) WL LIMIT PCPN COVG AND INTENSITY. TENDED TOWARD A BLEND OF ETA/GFS MOS GUIDANCE FOR MIN TEMPS FCST...WITH THE LOWER READINGS OVER THE W WITH MORE VIGOROUS LLVL DRYING LATE. ON WED...AN INCRSG N TO NW FLOW WL ADVECT COLDER AIR NOW OVER SCNTRL CAN INTO THE UPR GRT LKS. DURING MID WINTER...WOULD HAVE TO CONSIDER LES HEADLINES...BUT TIMING OF ARRIVAL OF COLDER AIR DURING THE DIURNAL HTG TIME AS WELL AS ACYC NATURE OF LARGER SCALE FLOW WL LIMIT LES BAND DVLPMNT/COVG/INTENSITY. ALTHOUGH FCST SHARP INVRN ARND H85 OR SO WL RESULT IN INCRSG SC DVLPMNT WITH THE DIURNAL HTG... THIS LO INVRN SHOULD LIMIT THE POTENTIAL FOR ANY INSTABILTY SHSN THAT MIGHT OTRW DVLP WELL INLAND WITH SFC HTG/INFLUX OF LLVL MSTR OFF THE LK. MIXING TO H85-825 ON GFS FCST SDNGS YIELDS HI TEMPS ARND 40 OVER THE SCNTRL...WHICH WL BE WARMEST WITH DOWNSLOPING NNW FLOW. LONG TERM DISCUSSION (WEDNESDAY NIGHT THROUGH NEXT TUESDAY)... TROUGHING IN THE GREAT LAKES TO BEGIN THE PERIOD GRADUALLY GETS REPLACED BY FLATTER FLOW ALOFT. AS TROUGH RUNS INTO STRONG RIDGE OVR NORTH ATLANTIC/GREENLAND EXPECT IT TO STALL THIS WEEKEND WHEN IT REACHES NORTHERN NEW ENGLAND/EASTERN CANADA. USUALLY THIS PATTERN RESULTS IN A COLDER PATTERN FOR GREAT LAKES/MID ATLANTIC AND THIS TIME IS NO EXCEPTION. AT THE LEAST...EXPECT BLO NORMAL TEMPS THROUGH THE WEEKEND. ALSO...WITH H85 TEMPS TOWARD -12C COULD END UP WITH LIGHT LK EFFECT SNOW SHOWERS. DUE TO ONSHORE FLOW AND AT LEAST WEAK OVER WATER INSTABILITY...WENT AHEAD AND LINGERED SNOW SHOWERS INTO FRIDAY NEAR LK SUPERIOR. BEST CHANCE FOR A PERIOD OF SOME ACCUMULATION WOULD BE LATE WED NIGHT INTO THU WITH ADDITIONAL LIFT FM SHORTWAVE AND SFC TROUGH PASSING ACROSS EASTERN HALF OF LAKE SUPERIOR. EVENTUALLY...FLOW ALOFT BECOMES FLATTER OVR MUCH OF WESTERN HALF OF THE CONUS WHICH ALLOWS SHORTWAVE TROUGH CURRENTLY OFFSHORE OF WESTERN CONUS TO SHIFT INTO THE MIDDLE PORTION OF THE CONUS ON FRIDAY. ATTM...TRACK OF SHORTWAVE/SFC TROUGH KEEPS SNOW TO THE SOUTH OF CWA. YET...SINCE LARGE HIGH PRESSURE OVR CANADA HAS NOT ARRIVED BY THAT TIME...THERE IS STILL A POTENTIAL FOR TRACK OF THE LOW TO SHIFT FARTHER NORTH. DPROG/DT OF GFS/ECMWF INDICATE AN INCREASING NORTHERLY TREND TO NORTH EDGE OF SNOW SHIELD STREAKING ACROSS WI/IL. ON LATEST MODELS...THIS IS NOW INTO CNTRL WI. WILL KEEP DRY FCST FOR FRI ALONG WI BORDER...BUT SNOW MAY NEED TO BE INCLUDED IN LATER FORECASTS IF SIMILAR TREND CONTINUES. ANOTHER SHORTWAVE EMERGING FM TROUGH OVER WESTERN CANADA TRIES TO MAKE A RUN INTO WESTERN GREAT LAKES BY LATE WEEKEND. ALTHOUGH SFC HIGH/DRY AMBIENT AIR SHOULD KEEP PCPN TO A MINIMUM...INCLUDED A SMALL MENTION OF LIGHT SNOW SAT NIGHT INTO SUN AS WEAK SFC TROUGH TRIES TO MOVE THROUGH. GFS AN OUTLIER AT THIS POINT SHOWING STORM IN NORTHERN STREAM SHIFTING ACROSS NEXT TUE. 12Z ECMWF...OTHER GUIDANCE...AND THE HPC PREFERENCE...IS TO KEEP STORM TRACK FARTHER SOUTH SO CARRIED A DRY FCST MON/TUE. TEMPS REMAIN ON THE COOL SIDE OF CLIMATOLOGY THROUGH THE MIDDLE OF NEXT WEEK. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... APPEARS NARROW BAND OF HIGHER SFC DWPTS SHOULD BE CROSSING THE KEWEENAW ATTM. SO...HAVE MAINTAINED A MENTION OF LIFR CIGS AND MVFR VIS IN -FZDZSN THRU ABOUT 07Z AT KCMX. THIS IS INLINE WITH A FEW OBS THAT REPORTED -DZ/FLURRIES UPSTREAM IN NE MN EARLIER IN THE NIGHT. OTHERWISE...SLIGHTLY DRIER AIR IS SPREADING OVER WRN LAKE SUPERIOR AND WILL MAKE INROADS INTO UPPER MI FROM THE NW DURING THE OVERNIGHT. SINCE IT`S NOT A STRONG PUSH OF DRIER AIR...ANTICIPATE CIGS REMAINING IN THE MVFR RANGE FOR THE BULK OF THE FCST PERIOD AT KCMX. SOME LAKE EFFECT -SHSN MAY DEVELOP IN THE EVENING AS AIRMASS BECOMES COLDER. AT KSAW...EXPECT MVFR CIGS TO DOMINATE THRU THE NIGHT INTO THE AFTN. THERE MAY BE A PERIOD LATE IN THE NIGHT/EARLY MORNING WHERE CLOUDS SCT OUT AS DRIER AIR AND DOWNSLOPING NW WINDS WORK TO BREAK UP CLOUD DECK. IF CLOUDS DO SCT OUT...DAYTIME HEATING SHOULD RESULT IN REDEVELOPMENT OF MVFR CIGS MID/LATE MORNING. CLOUDS SHOULD LIFT TO VFR IN THE AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW OVER NORTHERN ONTARIO WILL DRAG A COLD FRONT ACROSS LAKE SUPERIOR OVERNIGHT. THE LOW WILL DEEPEN AS IT MOVES TO JAMES BAY ON WEDNESDAY. LOOK FOR HIGH PRESSURE TO BUILD INTO THE NORTHERN PLAINS WEDNESDAY EVENING AND INTO THE UPPER GREAT LAKES ON THURSDAY. THIS HIGH WILL THEN BUILD THROUGH FRIDAY EVENING AND REMAIN NEARLY STATIONARY THROUGH SUNDAY. ALTHOUGH WINDS MAY REACH 30 KNOTS ON WEDNESDAY NIGHT/THURSDAY WITH THE INFLUX OF COLD AIR IN ADVANCE OF THE BUILDING RIDGE...NO GALES ARE EXPECTED DURING THIS FORECAST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SYNOPSIS/SHORT TERM DISCUSSION...KC LONG TERM DISCUSSION...JLA AVIATION...ROLFSON MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 435 AM CDT WED MAR 19 2008 .SHORT TERM...TODAY THROUGH THURSDAY NIGHT...THE SQUALL LINE WAS NEARING THE I-55 CORRIDOR AT 330 AM AND STRONGEST FROM HIGHWAY 82 AND SOUTHWARD. OUR EASTERN COUNTIES WILL BE UNDER THE GUN DURING THE NEXT SEVERAL HOURS. THE LINE IS EXPECTED TO BE CLOSE TO THE MS/AL STATE LINE BY 7 AM ESSENTIALLY ENDING THE SEVERE WEATHER THREAT FOR OUR AREA. WATER VAPOR IMAGERY/RUC ANALYSIS SHOWS THE CLOSED UPPER LOW OVER THE RED RIVER VALLEY WHILE SURFACE ANALYSIS PLACES THE LOW OVER SOUTHEAST ARKANSAS. THE SURFACE LOW WILL TRACK TO THE NORTHEAST ACROSS NORTHEAST MISSISSIPPI TODAY WHILE THE CLOSED UPPER LOW OPENS UP AND SHIFTS EAST. WATER VAPOR IMAGERY IS ALSO SHOWING THE EXPECTED DRY SLOTTING WRAPPING UP AROUND THE EAST SIDE OF THE UPPER LOW...OVER OUR WESTERN ZONES. HOWEVER...REGIONAL RADARS ARE SHOWING A LINE OF SHOWERS ALONG THE TRAILING COLD FRONT BACK OVER WESTERN LOUISIANA SO WL MAINTAIN RAIN CHANCES THIS MORNING FOR THE FRONT. THE COLD FRONT IS EXPECTED TO BE EAST THE I-55 CORRIDOR BY NOON AND EAST OF OUR CWA BY LATE AFTERNOON. ALTHOUGH THE FRONT WILL BE TO OUR EAST...THE UPPER TROUGH AXIS AND ASSOCIATED CLOUD COVER WON`T SHIFT EAST UNTIL TONIGHT. THE WINDS BEHIND THE COLD FRONT WILL APPROACH LOCAL LAKE WIND ADVISORY CRITERIA FOR A COUPLE OF HOURS THIS MORNING OVER OUR DELTA REGION. WL HOLD OFF ISSUANCE FOR NOW AND REEVALUATE LATER. THUS WL ALLOW THE CURRENT LAKE WIND ADVISORY FOR THE WHOLE AREA TO EXPIRE AT 7 AM. HIGH PRESSURE WILL BUILD OVER OR CWFA FROM THE WEST TONIGHT INTO THURSDAY BEFORE SHIFTING EAST OF OUR CWFA THURSDAY NIGHT. THE COOLER AND DRIER AIR BEHIND THE FRONT WILL RESULT IN BELOW NORMAL TEMPERATURES THROUGH FRIDAY MORNING. .LONG TERM...FRIDAY THROUGH WEDNESDAY...OVERALL MEDIUM RANGE MODELS ARE DRIER IN THE LONG TERM BUT MAINTAIN RAIN CHANCES FOR OUR AREA FOR SUNDAY INTO SUNDAY NIGHT. BY FRIDAY MORNING HIGH PRESSURE AT THE SURFACE WILL BE CENTERED OVER THE SOUTHEAST CONUS AND SLIDE EAST INTO THE ATLANTIC DURING THE DAY. OUR LOW LEVEL FLOW WILL VEER TO THE SOUTH BUT REMAIN LIGHT AND NOT WORK TO INCREASE MOISTURE MUCH BEFORE A DRY COLD FRONT MOVES THROUGH OUR CWFA SATURDAY. THE COLD FRONT IS EXPECTED TO MAKE IT TO THE GULF COAST BEFORE STALLING. HIGH PRESSURE CENTERED OVER THE GREAT LAKES REGION WILL BRIEFLY RIDGE SOUTH INTO OUR AREA INTO SUNDAY BEFORE SLIDING EAST AND ALLOWING A STRONGER DISTURBANCE TO MOVE INTO OUR REGION SUNDAY NIGHT. THERE AREA STRENGTH AND TIMING DIFFERENCES BETWEEN THE GFS AND THE ECMWF BUT A POTENT NORTHERN STREAM SHORTWAVE WILL DROP SOUTH OUT OF THE NORTHERN PLAINS AND DEEPEN A TROUGH OVER OUR REGION. THIS WILL BRING AN INCREASE IN RAIN CHANCES BY SUNDAY AFTERNOON AND LAST INTO SUNDAY NIGHT. THE ECMWF IS DEEPER AND A TAD FASTER THAN THE GFS WITH THIS FEATURE. MONDAY MORNING TEMPERATURES ARE EXPECTED TO DIP INTO THE LOWER 30S IN THE NORTH RESULTING IN PATCHY FROST. IF THE GFS TRENDS TOWARD THE ECMWF EVEN COLDER MORNING LOWS COULD BE REALIZED MONDAY MORNING. RIDGING SURFACE AND ALOFT WILL BUILD OVER OUR REGION MONDAY THROUGH WEDNESDAY RESULTING IN A RETURN TO DRY WEATHER AND A WARMING TREND TOWARD NEAR NORMAL TEMPERATURES. && .AVIATION...SQUALL LINE WILL MOVE EAST OVER THE EASTERN HALF OF MISSISSIPPI THROUGH 13Z BEFORE SHIFTING EAST INTO ALABAMA. OUTSIDE OF THUNDERSTORM AREAS...WIDESPREAD MVFR CEILINGS WILL PREVAIL TODAY. A TRAILING COLD FRONT WILL MOVE ACROSS THE AREA LATER TODAY WITH A FEW ADDITIONAL SHOWERS POSSIBLE MAINLY IN THE NORTH. AN UPPER LEVEL TROUGH AXIS WILL NOT SHIFT EAST ACROSS THE AREA UNTIL TONIGHT. BREAKS IN THE CLOUDS MAY OCCUR IN THE SOUTH TODAY BUT THE LOW CLOUDS WILL LIKELY HANG IN THE NORTH UNTIL THE UPPER TROUGH AXIS SHIFTS EAST. && .PRELIMINARY POINT TEMPS/POPS... JACKSON 63 41 70 42 / 37 0 0 0 MERIDIAN 67 42 69 38 / 61 0 0 0 VICKSBURG 62 41 69 42 / 24 0 0 0 HATTIESBURG 67 43 72 39 / 52 0 0 0 NATCHEZ 63 43 68 41 / 14 0 0 0 GREENVILLE 61 40 68 45 / 41 0 0 0 GREENWOOD 62 39 68 43 / 50 0 0 0 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...LAKE WIND ADVISORY UNTIL 7 AM CDT THIS MORNING FOR MSZ018-019- 025>066-072>074. LA...LAKE WIND ADVISORY UNTIL 7 AM CDT THIS MORNING FOR LAZ007>009- 015-016-023>026. AR...LAKE WIND ADVISORY UNTIL 7 AM CDT THIS MORNING FOR ARZ074-075. && $$ 22 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1240 AM CDT WED MAR 19 2008 ...UPDATE TO AVIATION... .UPDATE... RAINFALL CONTINUES ACROSS THE REGION. SUBSTANTIAL FLOODING WILL CONTINUE INTO WEDNESDAY MORNING WITH MODERATE TO MAJOR RIVER FLOODING EXPECTED WEDNESDAY AND LIKELY BEYOND. STRONG UPPER LOW NOW BEGINNING TO PROGRESS A BIT INTO TEXAS. ELONGATED UPPER JET ORIENTED FROM CENTRAL/EAST TEXAS THROUGH EASTERN KANSAS AND INTO THE GREAT LAKES REGION. UPPER DIFFLUENCE REMAINS PRONOUNCED ACROSS THE MIDDLE OF THE NATION. IN THE LOWER LEVELS...A LOW LEVEL JET CONTINUES TO SLOWLY SHIFT EASTWARD INTO THE LOWER MS RIVER VALLEY REGION. AT THE SFC...A COLD FRONT EXTENDS FROM JUST SOUTHEAST OF THE BOOT HEEL OF MO TO NEAR LITTLE ROCK AND TEXARKANA. A SFC LOW CONTINUES TO SLOWLY RIDE NORTHEASTWARD ALONG THIS FRONT AND IS CURRENTLY LOCATED OVER SOUTHWEST ARKANSAS. LOOKING AT THE LATEST RUC INITIALIZATIONS...FRONTOGENESIS IN BOTH THE LOW AND MID LEVELS WILL BE IN PLACE ALONG AND SOUTHEAST OF THE INTERSTATE 44 CORRIDOR THROUGH THE OVERNIGHT HOURS. THE UPPER LOW WILL BE SLOW TO TRAVERSE TEXAS...LIFTING TO THE EAST NORTHEAST OVERNIGHT. THE UPPER LOW OVER TEXAS WILL WEAKEN A BIT AS IT DOES SO...JOINING THE NORTHERN STREAM WEDNESDAY MORNING. THIS WILL RESULT IN A SLOW END TO OUR LIGHT TO MODERATE RAINFALL. EASTWARD PROGRESS OF THE BACK EDGE OF THE THIS RAINFALL WILL BE SLOW TO NEGLIGIBLE OVER THE NEXT SEVERAL HOURS...WAITING UNTIL THE AFOREMENTIONED SFC LOW IS EAST OF THE AREA AND THE UPPER LOW ACCELERATES TO THE EAST NORTHEAST. STRONG UPPER SUPPORT AND DEEP CONVERGENCE SHOULD MAINTAIN A NEARLY SOLID SHIELD OF RAINFALL TONIGHT. THE GOING FORECAST OF ONE TO THREE INCHES OF RAINFALL TONIGHT LOOKS GOOD...HIGHER AMOUNTS OF THREE TO FIVE INCHES ARE POSSIBLE OVER SOUTH CENTRAL MISSOURI. GAGAN && .DISCUSSION... HEAVY RAIN CONTINUES ACROSS SOUTHWEST AND CENTRAL MISSOURI THIS AFTERNOON. THOUGH WE HAVE SEEN TREMENDOUS RAINFALL AMOUNTS SO FAR...WE STILL HAVE A PERIOD OF HEAVY RAINFALL THAT WILL MOVE UP INTO THE AREA FROM NORTHWEST ARKANSAS AND EASTERN OKLAHOMA. ANY ADDITIONAL RAINFALL WILL ONLY MAKE FLOODING MATTERS WORSE. SHORT TERM (TONIGHT THROUGH THURSDAY)... FRONT EXTENDS FROM SURFACE LOW OVER SOUTH CENTRAL ARKANSAS NORTHEAST INTO THE MISSOURI BOOT HEEL THIS AFTERNOON. PROFILER DATA OVER SOUTHWEST ARKANSAS CONTINUES TO SHOW A STRONG 50KT LOW LEVEL JET EXTENDING FROM SOUTHWEST ARKANSAS UP INTO SOUTHEAST MISSOURI. MOISTURE IS RIDING UP ALONG THIS BOUNDARY INTO NORTHEAST OKLAHOMA/NORTHWEST ARKANSAS...INTO MOST OF THE CWA. UPPER LOW STILL DOWN OVER SOUTHWEST MISSOURI. SO THE MOISTURE TRAIN WILL STAY IN TACT OVER NIGHT. SERIOUS MAJOR TO RECORD FLOODING IS IN THE PROCESS OF COMING TO FRUITION. HEAVY RAIN WILL CONTINUE OVERNIGHT WITH AN ADDITIONAL 1.5-2.5 INCHES EXPECTED ALONG THE INTERSTATE 44 CORRIDOR. HPC QPF GUIDANCE SHOWING ANOTHER 2-3 INCHES EXPECTED FOR COMMUNITIES SOUTH AND EAST OF INTERSTATE 44 FOR TONIGHT. LATEST RUC GUIDANCE SHOWING A WAVE ALONG THE FRONT PUSHING INTO SOUTHERN MISSOURI THIS EVENING. FLASH FLOOD WARNINGS ARE WILL MOST LIKELY BE EXTENDED THROUGH THE OVERNIGHT AREAS TO REFLECT THESE PRECIP AMOUNTS. UPPER LOW OPENS AFTER MIDNIGHT AND TRACKS ACROSS SOUTHEAST MISSOURI WEDNESDAY MORNING. PRECIPITATION WILL END FROM WEST TO EAST WEDNESDAY MORNING. CLAYCOMB LONG TERM (FRIDAY THROUGH TUESDAY)... IN THE LONG TERM...A PROGRESSIVE PATTERN DOMINATED BY NORTHWEST FLOW ALOFT WILL DOMINATE OUR WEATHER PATTERN. SEVERAL UPPER LEVEL DISTURBANCES WILL QUICKLY PROGRESS THROUGH THIS FLOW...EACH HAVING AT LEAST A MINOR EFFECT ON OUR SENSIBLE WEATHER. THE NICEST DAY DURING THE PERIOD WILL LIKELY BE FRIDAY AS LOW PRESSURE TO THE NORTHWEST ISSUES A WARM AIR ADVECTION REGIME INTO THE AREA BRIEFLY. THIS LOW WILL BE QUICK TO MOVE THROUGH...LARGELY AFFECTING NORTHERN MISSOURI AND PERHAPS BRINGING A CHANCE FOR LIGHT SHOWERS TO OUR NORTHERN CWA. THE LOW LEVELS LOOK TO BE QUITE DRY BUT WE MAY HAVE ENOUGH LIFT AND MOISTURE IN THE MID LEVELS TO CREATE A FEW RAIN SHOWERS. A COLD FRONT SWEEPS THROUGH ON THE BACK SIDE OF THIS SYSTEM WITH MODERATE COLD AIR ADVECTION IN ITS WAKE. ANOTHER UPPER LEVEL IMPULSE DIVES SOUTHEAST BY LATE SATURDAY. THE ECMWF IS MORE AGGRESSIVE WITH PRECIP FOR THIS SYSTEM. WITH THE AMOUNT OF MID LEVEL LIFT AND THE JET PATTERN PRESENT...THIS BECOMES BELIEVABLE. HOWEVER...THERE IS ONCE AGAIN A QUESTION OF JUST HOW MUCH MOISTURE WILL BE AVAILABLE. IT APPEARS THAT THE GULF WILL OPEN UP BY LATE MONDAY AND SLIGHTLY WARMER TEMPERATURES ALONG WITH MORE SIGNIFICANT MOISTURE WILL BE BROUGHT NORTH. THE ECMWF HAS BEEN CONSISTENT IN BRINGING IN A WELL DEVELOPED STORM SYSTEM WITH A CUTOFF LOW AT 500 HPA. THE GFS ON THE OTHER HAND...HAS A WEAK WAVE IN THE UPPER FLOW MOVING THROUGH THE GREAT LAKES REGION. HAVE TRENDED TOWARD THE ECMWF AND HAVE CHANCE POPS IN THE GRIDS FOR THE MONDAY/TUESDAY TIME FRAME WITH THE MENTION OF THUNDER. AT THIS TIME...IT APPEARS THERE WOULD BE SIGNIFICANT COLD AIR BROUGHT IN WITH THIS SYSTEM. SNOW DOES NOT APPEAR LIKELY...BUT CAN NOT BE COMPLETELY RULED OUT. FUTURE MODEL RUNS WILL PROVIDE MORE DETAIL INTO THIS PORTION OF THE FORECAST. BARJENBRUCH && .AVIATION... FOR THE 06Z TAF PACKAGE...FORECAST CHALLENGE FOR THE NEXT 6 TO 12 HOURS IS THE DEPARTING STORM SYSTEM. THE WESTERN EDGE OF THE AREA OF RAINFALL THAT HAS PLAGUED THE REGION IS SLOWLY WORKING ITS WAY TOWARD THE SGF AERODROME. CIGS/VIS HAVE BEEN VARIABLE AT BOTH JLN AND SGF OVER THE PAST FEW HOURS...REALLY HUGGING MVFR/IFR AT SGF. WITH ANOTHER AREA OF RAINFALL COMING ACROSS THE SGF AERODROME... HAVE OPTED TO CONTINUE MENTIONING IFR CIGS. VISIBILITY SHOULD VARY FROM MVFR TO VFR BASED ON RAINFALL INTENSITY. AT JLN...CIGS HAVE RISEN TO THE MVFR CATEGORY AND THIS LOOKS TO PERSIST THROUGH THE OVERNIGHT. IMPROVING VIS/CIG IS EXPECTED DURING THE LATE MORNING HOURS WITH CLEARING BY MIDDAY. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLASH FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR MOZ055>058- 066>071-077>083-088>098-101>106. KS...FLASH FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR KSZ073-097-101. && $$ mo AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1135 PM CDT TUE MAR 18 2008 .AVIATION... 1135 PM EXPECT A FEW HOURS MORE OF RAIN AND MVFR CEILINGS...THEN BEFORE SUNRISE CIGS SHOULD LIFT AS UPPER SYSTEM FINALLY MOVES ON EAST. REST OF PERIOD WILL BE VFR. 84 && .UPDATE... 743 PM CLEARING THE TORNADO WATCH WITH COLD FRONT NOW THROUGH ALL OF NORTH TEXAS. OTHERWISE HAVE MADE MINOR CHANGES TO LOWER LOW TEMPS A LITTLE AND TWEAKS TO SKY/POPS THROUGH TONIGHT. UPPER LEVEL LOW STILL BACK IN SW TEXAS WILL BE MOVING OVER NORTH TEXAS DURING THE OVERNIGHT HOURS. STRONG FRONTOGENESIS ASSOCIATED WITH THE CORE OF THE UPPER LEVEL LOW WILL MAINTAIN UPWARD VERTICAL MOTIONS OVER THE AREA AND SQUEEZE OUT THE REMAINING MOISTURE ALOFT. AREAS OF MODERATE RAIN ARE EXPECTED TO CONTINUE...BUT RAINFALL RATES SHOULD STAY LESS THAN 1/4 INCH AN HOUR...WITH ADDITIONAL TOTALS OF A HALF INCH TO AN INCH NORTH OF A COMANCHE TO CANTON LINE. RAIN TOTALS WILL BE LESS THAN A HALF INCH IN THE SOUTHERN ZONES. TR.92 && .PREV DISCUSSION... /ISSUED 659 PM CDT TUE MAR 18 2008/ UPDATE... TORNADO WATCH WILL CONTINUE FOR ANDERSON AND HENDERSON COUNTY FOR AT LEAST THE NEXT HOUR BEFORE WE CLEAR IT. OTHERWISE...STRONG PRESSURE RISES ARE OCCURRING AND RUC FORECASTS SHOW 925 MB WINDS APPROACHING 50 KNOTS TONIGHT. STRONG ISENTROPIC DESCENT AND COLD ADVECTION WILL FAVOR SOME MIXING OF THIS WIND DOWN TO THE SURFACE SO HAVE ISSUED A WIND ADVISORY FOR THE ENTIRE AREA THROUGH 4 AM. NO OTHER CHANGES AT THIS TIME. TR.92 PREV DISCUSSION... /ISSUED 550 PM CDT TUE MAR 18 2008/ AVIATION... 550 PM ACT SEEING ABOUT THE LAST HOUR OR TWO OF THE WORST TSTMS. DFW AREA ALSO HAS THE STRONGEST STORMS TO THE EAST. EXPECT RAIN TO CONTINUE IN METROPLEX FOR NEXT 3-4 HOURS WITH SOME EMBEDDED TSTMS...THEN TAPER OFF TO INTERMITTENT SHOWERS OVERNIGHT. RAIN SHOULD END AROUND SUNRISE AS UPPER SYSTEM FINALLY MOVES EAST. MVFR CEILINGS SHOULD CONTINUE THROUGH ABOUT MIDNIGHT WHEN DEEPER LLVL DRY AIR CAUSES THEM TO LIFT TO VFR. 84 UPDATE... 530 PM HAVE UPDATED TO INCLUDE THE NEW TOR BOX FOR THE EXTREME EAST. TORNADO THREAT ONLY WILL END IN A COUPLE HOURS AND WATCH WILL BE CANCELED WELL BEFORE THE LISTED EXPIRATION TIME. OTHERWISE HAVE AMENDED THE FORECAST TO INCREASE WIND SPEEDS TONIGHT...BUT WILL HOLD OFF ON A WIND ADVISORY FOR NOW...AWAITING TO SEE ISALLOBARIC TRENDS UNFOLD WITH DYNAMIC SYSTEM MOVING ACROSS. TR.92 DISCUSSION... AREA OF RAIN AND THUNDERSTORMS CURRENTLY MOVING SOUTH TO NORTH OVER MUCH OF NORTH TEXAS IS BEING FED BY A 50+ KT LOW LEVEL JET. COLD FRONT CONTINUES ITS SLOW MARCH SOUTHEASTWARD ACROSS THE AREA. AREAS AHEAD OF THE FRONT STILL HAVE A CHANCE FOR SEVERE WEATHER... ALTHOUGH SO FAR HEAVY RAIN AND FLASH FLOODING HAVE PROVED TO BE THE MAIN HAZARDS. MOST AREAS HAVE RECEIVED BETWEEN ONE AND TWO INCHES SO FAR WITH ANOTHER INCH OR MORE STILL POSSIBLE. EVEN AS THE FRONT EXITS STAGE RIGHT...WE WILL SEE RAIN CHANCES INTO THE EVENING HOURS AND OVERNIGHT AS THE MAIN UPPER LOW ROTATES OVER THE REGION. LARGELY UNI-DIRECTIONAL SHEAR WILL CONTINUE TO PROMOTE TRAINING OF CELLS AND FLASH FLOODING. WRAP-AROUND PRECIP WILL LINGER IN THE NORTHEAST INTO THE EARLY MORNING HOURS BUT SHOULD SHUT OFF RATHER QUICKLY. UPPER PATTERN WILL BECOME FLAT AND ZONAL FROM WEDNESDAY NIGHT THROUGH THE WEEKEND. PLEASANT TEMPERATURES ARE EXPECTED WITH SOUTHERLY FLOW RETURNING THURSDAY MORNING. CLEAR SKIES WILL ALLOW FOR AFTERNOON READINGS IN THE 70S THURSDAY AND FRIDAY. THERE WILL BE A SLIGHT COOL DOWN OVER THE WEEKEND AS A WEAK FRONT MOVES THROUGH THE AREA. RAIN CHANCES WITH THIS SYSTEM LOOK LOWER THAN PREVIOUSLY THOUGHT WITH MOST OF THE ENERGY WELL TO OUR NORTH. HAVE LEFT SLIGHT CHANCE POPS IN FOR NOW AND WILL CONTINUE TO WATCH THIS SYSTEM. QUIET WEATHER IS EXPECTED FOR THE BEGINNING OF NEXT WEEK WITH THE MAIN STORM TRACK STAYING ACROSS THE NORTHERN PLAINS. SH/13 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 44 66 43 72 50 / 100 0 0 0 5 WACO, TX 45 69 41 72 52 / 60 0 0 0 5 PARIS, TX 45 64 41 69 46 / 100 20 0 0 5 DENTON, TX 43 66 40 72 49 / 100 5 0 0 5 MCKINNEY, TX 45 66 39 73 48 / 100 20 0 0 5 DALLAS, TX 44 67 44 73 52 / 100 5 0 0 5 TERRELL, TX 45 65 40 72 50 / 90 10 0 0 5 CORSICANA, TX 46 67 41 73 49 / 60 0 0 0 5 TEMPLE, TX 46 70 40 72 48 / 50 0 0 0 5 && .FWD WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 7 AM CDT WEDNESDAY FOR THE FOLLOWING ZONES: TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175. WIND ADVISORY UNTIL 4 AM CDT WEDNESDAY FOR THE FOLLOWING ZONES: TXZ091>095-100>107-115>123-129>135-141>148-156>162-174-175. && $$ 99/99 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 437 AM MDT WED MAR 19 2008 .SHORT TERM... (TODAY AND TONIGHT) CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING MODERATE WEST TO NORTHWEST FLOW ALOFT ACROSS THE REGION WITH A MINOR SHORT WAVE TROUGH MOVING ACROSS THE NORTHERN TIER AND INTO THE NORTHERN ROCKIES ATTM. CURRENT SATELLITE INDICATING GENERALLY CLEAR SKIES ACROSS SOUTH CENTRAL AND SOUTHEAST COLORADO WITH SOME HIGH CLOUDS ACROSS NORTHWEST COLORADO AND A FEW WAVE CLOUDS DEVELOPING ACROSS THE FRONT RANGE. TODAY AND TONIGHT...MODELS INDICATING INCREASING WEST TO NORTHWEST FLOW ACROSS THE REGION THIS MORNING WITH MODERATING WESTERLY FLOW THROUGH THE AFTERNOON...AS NORTHERN ROCKIES SYSTEM CONTINUES INTO THE UPPER MIDWEST. WITH THE SYSTEM STAYING FURTHER NORTH...MODELS INDICATING LESS AVAILABLE MOISTURE MOVING INTO THE REGION...AND HAVE CUT BACK POPS CONFINING SLIGHT CHANCES TO THE HIGHEST WEST FACING SLOPES OF THE CENTRAL MTS THIS AFTERNOON. WITH AMPLE SUNSHINE...SHOULD SEE BREEZY WESTERLY WINDS MIXING DOWN ACROSS THE AREA...OWNING TO HIGHS CLOSER TO THE WARMER SIDE OF GUIDANCE ONCE AGAIN. WESTERLY FLOW TO INCREASE ACROSS THE REGION TONIGHT AS A STRONGER SHORT SYSTEM MOVING ACROSS THE WEST COAST CONTINUES INTO THE SOUTHERN GREAT BASIN. LEE TROUGHING STRENGTHENS ACROSS THE I-25 CORRIDOR OVERNIGHT AND WITH WAA AND BREEZY DOWNSLOPE WINDS...SHOULD SEE FAIRLY MILD OVERNIGHT LOWS...ESPECIALLY ACROSS THE LOWER EASTERN SLOPES AND IMMEDIATE ADJACENT PLAINS. -MW .LONG TERM... (THURSDAY THROUGH TUESDAY) ...A WEAK SYSTEM THURSDAY AND POSSIBLY STRONGER SYSTEM OVER THE WEEKEND... .THURSDAY...SHORTWAVE PASSES THROUGH THE STATE THURSDAY NIGHT. MAIN IMPACT FOR PRECIPITATION WILL BE IN THE CENTRAL MOUNTAINS...AND THE BEST MOISTURE...LIFT AND PRECIPITATION WILL STAY TO THE NORTH OF THE CWA. GRIDS HAVE GENERALLY 1 TO 4 INCHES FOR THE CENTRAL MOUNTAINS...WHICH IS BELOW ADVISORY CRITERIA. OTHER MAIN THREAT WITH THIS SYSTEM IS GUSTY SOUTHWEST WINDS ON THE PLAINS. SPC FIRE WEATHER DISCUSSION HAS A CRITICAL AREA EXTENDING INTO BACA COUNTY. NAM SURFACE FIELDS SHOW THE POTENTIAL FOR RED FLAG CONDITIONS IN BACA COUNTY. ON MONDAY MORNING...THUNDERSTORMS MOVED THROUGH BACA COUNTY WITH KSPD HAVING NEARLY AN INCH OF RAIN...AND FUELS MAY NOT BE CRITICAL. GIVEN THE SMALL AREA AND RECENT RAINS IN THIS REGION...WILL NOT ISSUE ANY FIRE WEATHER WATCH AT THIS TIME. WITH +4C AT 700MB AND SOUTHWEST WINDS...EXPECT A MILD DAY ON THE PLAINS WITH TEMPERATURES IN THE 70S. .FRIDAY...BEHIND THE TROUGH...A WEAK UPSLOPE SURGE WILL DEVELOP OVER THE PLAINS. AIR ALOFT COOLS MODESTLY...AND WITH THE STRONGER MID MARCH SUNSHINE...TEMPERATURES WILL STILL BE NEAR OR ABOVE NORMAL OVER THE REGION. WITH ANOTHER WEAK SHORTWAVE MOVING INTO THE STATE...KEPT SOME SLIGHT CHANCE TO CHANCE POPS OVER THE CENTRAL MOUNTAINS...AND ANY ACCUMULATIONS WILL BE LIGHT. .SATURDAY AND SUNDAY...STRONGER TROUGH WILL MOVE INTO THE REGION FROM THE NORTHWEST. SYSTEM IS STILL WELL OFF THE COAST AND IT IS TOUGH TO GET VERY SPECIFIC ABOUT THE SYSTEM. MODELS HAVE BEEN TRENDING STRONGER WITH THE TROUGH. 00Z EC AND 06Z GFS SUGGEST SATURDAY COULD BE A CHILLY DAY ON THE PLAINS WITH THE POTENTIAL FOR SOME PRECIPITATION. DECIDED TO ONLY MAKE MINOR CHANGES TO THE GRIDS AT THIS TIME. GRIDS STILL FOLLOW MEX NUMBERS CLOSELY. DEPENDING ON TIMING AND STRENGTH OF THE SYSTEM...MAXIMUMS ON SATURDAY OR SUNDAY COULD BE COOLER THAN IN THE GRIDS. BY SUNDAY AFTERNOON...EC AND GFS SUGGEST A LEE TROUGH TRYING TO DEVELOP WITH WARMER AIR MOVING INTO THE REGION. IF THESE TRENDS CONTINUE...DAYSHIFT MAY HAVE TO COOL AND MOISTEN THE WEEKEND GRIDS. IN THE CENTRAL AND SOUTHWEST MOUNTAINS...SYSTEM IS MOVING FAIRLY FAST AND MID LEVEL MOISTURE MAY BE LIMITED. EXPECT ACCUMULATIONS TO BE BELOW ADVISORY CRITERIA. .MONDAY AND TUESDAY...POLICY IS NOT TO CHANGE DAYS 6 AND 7 ON MIDSHIFT...UNLESS CHANGE IS SUBSTANTIAL. MODELS CONTINUE TREND OF SHORTWAVE RIDGE OVER THE REGION WITH MILD TEMPERATURES. CURRENT GRIDS HAVE THIS HANDLED WELL. --PGW-- && .AVIATION...VFR CONDITIONS EXPECTED ACROSS THE AREAS AND TAF SITES TODAY AND TONIGHT. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/06 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1023 AM CDT WED MAR 19 2008 .DISCUSSION... ISSUED 1022 AM CDT WED MAR 19 2008 MOISTURE CHANNEL SATELLITE IMAGERY MATHCES UP THE BEST EDGE OF THE EXTENSIVE PRECIPITATION FIELD OVER OH VALLEY REGION WITH THE MAIN UPPER 500 MB TROUGH. THIS ALSO SEEN IN THE PROFILER DATA AS THE TROUGH NOW BEGINNING TO MOVE TO THE EAST. RUC MODEL SHOWS THE PROG OF THE UPPER TROUGH TO SLOWLY MOVE TO THE EAST TODAY...FINALLY BRINGING AN END TO THE PCPN BY LATE AFTERNOON. WITH THE CONTINUED MODERATE RAIN OVER PORTIONS OF THE SOUTHEAST CWA...CONTINUED THE FLOOD WATCH THROUGH THE AFTERNOON WITH THE AREAL FLOOD WARNING FOR THE EXTREME SOUTHEAST COUNTIES. MADE SOME MINOR MODIFICATIONS TO THE TEMPERATURE GRIDS FOR THIS AFTERNOON...LOWERING THEM DUE TO THE CLOUD COVER AND PCPN. ALSO SLOWED DOWN THE CLEARING OF THE CLOUDS A LITTLE DURING THE AFTERNOON. GOETSCH && .AVIATION... ISSUED 648 AM CDT WED MAR 19 2008 PIA...BMI AND SPI WILL SEE MVFR CIGS THROUGH ABOUT 18Z WITH WINDS OUT OF THE N TO NW. MODEL INDICATES THE LOW LEVEL CLOUDS SCATTERING OUT AROUND THE SAME TIME LEAVING ONLY SOME CIRRUS AROUND INTO THE NIGHT. THEN OVERNIGHT...MID LEVEL CIGS OF AROUND 15KFT WILL MOVE IN AHEAD OF THE NEXT SYSTEM FROM THE WEST. DEC AND CMI WILL SEE IFR CIGS AS THEY REMAIN ON THE NORTHERN EDGE OF THE PCPN. THEREFORE WILL ALSO HAVE VCSH AT BOTH SITES THIS MORNING FOR A FEW HOURS. CIGS WILL GRADUALLY IMPROVE DURING THE MORNING AND INTO AFTERNOON HOURS...BUT CIGS WILL NOT SCATTER OUT UNTIL AROUND 23-00Z...LEAVING CIRRUS FOR MOST OF THE NIGHT. THEN DEC AND CMI WILL SEE INFLOW OF MID LVL CLOUDS TOWARD TOMORROW MORNING. AUTEN && .PREV DISCUSSION... ISSUED 335 AM CDT WED MAR 19 2008 SHORT TERM...TODAY THROUGH FRIDAY. MODERATE TO LOCALLY HEAVY RAINFALL CONTINUES TO FALL ACROSS THE EASTERN 2/3RDS OF THE CWA THIS MORNING...WITH IMPRESSIVE RAINFALL TOTALS CONTINUING TO MOUNT UP. NOT MUCH IN THE WAY OF REPORTS DURING THE OVERNIGHT HOURS...SO FAR 5.95 INCHES 4 SE OF CLAY CITY HAS BEEN THE WINNER... AND THAT WAS AS OF 1030 PM. RIVERS ACROSS THE SOUTHEAST HAVE BEEN RESPONDING OVERNIGHT... BUT IN MANY CASES ARE QUITE SURPRISINGLY RUNNING BELOW RFC FORECASTS. NOTE THE LEVELING OFF IN THE HYDROGRAPH AT CLAI2 AND LAWI2. WITH THE SATURATED GROUND...EXPECT PRETTY MUCH ANY RAINFALL WE GET OVER THE NEXT 6-12 HOURS WILL BE PURE RUN OFF... AND SUSPECT THAT RIVERS IN THE SOUTHEASTERN CWA WILL BEGIN A STEADY CLIMB AGAIN LATER TODAY. WITH THE MAINSTEM WABASH ALREADY IN FLOOD...RIVER STAGES AT THE NORMALLY FLASHIER RIVERS SUCH AS THE LITTLE WABASH MAY NIGHT DROP OFF AS QUICKLY AS THEY TYPICALLY DO. DECIDED TO EXTEND FLOOD WATCH THROUGH 18Z...ALTHOUGH MAIN AREAS OF CONCERN ARE ALREADY UNDER FLASH FLOOD AND/OR AREAL FLOOD WARNINGS AT THIS TIME. REPORTS OF WATER ISSUES ARE ESPECIALLY HARD TO COME BY AT NIGHT... ESPECIALLY FLOODED ROADWAYS IN RURAL AREAS... AND I AM WILLING TO HAZARD A GUESS THAT WE WILL RECEIVE SEVERAL MORE REPORTS OF PROBLEMS AS PEOPLE BEGIN WAKING UP AND TRAVELING THE ROADS... EVEN IN AREAS NORTH OF I-70. WATER VAPOR IMAGERY INDICATES DRY SLOT TRYING TO SNEAK INTO EXTREME SOUTHERN ILLINOIS THIS MORNING AHEAD OF THE UPPER LOW OVER TEXAS. THIS LOW WILL SHEAR OUT TO OUR EAST TODAY... KEEPING ANY DRY SLOTTING OFF TO OUR SE... AND MORE OF A DEFORMATION ZONE BAND HANGING BACK ACROSS THE FAR EASTERN CWA THROUGH EARLY AFTERNOON. ALTHOUGH H85 TEMPS DO DROP BELOW FREEZING LATER TODAY... SFC AND LOWER LEVELS REMAIN WARM AND QUITE SATURATED. WITHOUT ANY STRONG SFC CAA EXPECTED... DOUBT THERE WILL BE MUCH IF ANY ISSUES WITH PRECIP CHANGE OVER... AND WILL THEREFORE KEEP THE FORECAST ALL WET... WITH NO WHITE. WEAK HIGH PRESSURE WILL BUILD LATE TONIGHT THROUGH THURSDAY... AS PATTERN BECOMES MORE ZONAL AND ILL DEFINED. MODELS COMING INTO BETTER AGREEMENT ON TRANSITORY WAVES MOVING THROUGH THE QUASI- ZONAL FLOW REGIME THROUGH THE REST OF THE WORK WEEK. INCREASING LOW LEVEL WAA AHEAD OF THE FIRST WAVE WILL RESULT IN PRECIPITATION MAINLY NORTH OF I-74 THURSDAY NIGHT. INCREASED TEMPERATURES THURSDAY NIGHT AND FRIDAY SOUTH OF I-70 AS IT LOOKS LIKE WE WILL REMAIN SOUTH OF THE DEVELOPING WARM FRONT. COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL SWING THROUGH FRIDAY AFTERNOON. DEPENDING ON HOW MUCH WE CAN WARM UP WITHIN THE WARM SECTOR... WE COULD SEE SOME CONVECTIVE SHOWERS AND THUNDERSTORMS AHEAD OF THE COLD FRONT... ESPECIALLY ACROSS THE EAST AND SOUTHEAST CWA FRIDAY AFTERNOON. NOTE 06Z NAM CONTINUES A NORTHWARD TREND WITH THU/FRI SYSTEM. AS MENTIONED THE PAST FEW SHIFTS... SOUTH EDGE OF PRECIP AREA WILL BE SHARPLY DEFINED. FOR NOW... CONTINUED TO GO WITH A BLEND OF THE ECMWF/GFS SOLUTIONS... WHICH SUGGESTS PRECIP WILL AFFECT MAINLY OUR NORTHERN 1/3RD THURSDAY NIGHT... WHEREAS THE 06Z NAM KEEPS ALL THE PRECIP NORTH OF I-80. WILL NEED TO WATCH FOR ANY TRENDS HOWEVER. LONG TERM...SATURDAY AND SUNDAY. PATTERN LOOKS TO REMAIN QUASI-ZONAL ACROSS THE CONUS THROUGH THE WEEKEND... WITH THE ONLY PERSISTENT FEATURE ACROSS THE CONTINENT BEING A DEEP TROUGH CARVED OUT ACROSS THE CANADIAN MARITIMES...AND WEAK RIDGING OVER THE PACIFIC COAST. COLD FRONT WILL BE SOUTH OF THE AREA BY SATURDAY...WITH THE NEXT DISTURBANCE APPROACHING THE AREA SUNDAY. AT THIS POINT IT LOOKS TO WEAK AS IT MOVES THROUGH OUR AREA... BUT COULD BECOME A PRETTY DECENT STORM FOR THE EAST COAST BY EARLY NEXT WEEK. HARDIMAN && .ILX WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH UNTIL 4 PM CDT THIS AFTERNOON FOR ILZ044>046-052>057- 061>063-066>068-071>073. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 711 AM EDT WED MAR 19 2008 .AVIATION (12Z TAFS)... TEMPORARY IMPROVEMENT AT KSBN THIS MORNING ALG EDGE OF MID LVL TROUGH AND SUBSIDENCE ALG PCPN SHIELD EDGE. THIS WILL QUICKLY FILL IN W/MVFR STRATOCU WHICH EXTENDS WELL WEST INTO ERN IA. IFR CIGS CONT AT KFWA IN LT-MOD RAIN AND APPEARS THAT WILL CONT THROUGH 14Z OR SO BFR DIMINISHING AND SLOW IMPROVEMENT TO CIG HGTS ENSUES. W/UPR TROUGH ACCELERATING EWD INTO THIS AFTN AND BLDG RIDGING SFC AND ALOFT...EXPECT SKIES TO QUICKLY CLEAR OUT THROUGH THIS EVENING. && .PREV DISCUSSION... /ISSUED 412 AM EDT WED MAR 19 2008/ SHORT TERM... DEEP SRN STREAM SW TROUGH FINALLY EJECTING NEWD. BACKING MID LVL FLW AND TIGHT LL THERMAL GRADIENT LEADING TO EXPANDING AREA OF LT-MOD RAIN OVR SERN HALF OF CWA W/HEAVIER FNTL RAIN BAND NOW CLIPPING SE CORNER OF CWA. TRIMMED FLOOD WATCH FM EARLIER UPDATE MAY NOW ACTUALLY PAN OUT ALG A MARION...OTTAWA LINE SOUTH AND IN LIGHT OF SHRT TERM RUC SOLUTION WILL REMAIN IN PLACE THROUGH 12Z AS DRIVING MID LVL BAROCLINIC ZONE WORKS SLOWLY EWD. AFT THAT...HEAVIEST RAIN WILL SHIFT EWD INTO CNTRL/SRN OH CORRESPONDING TO BEST LL MSTR TRANSPORT W/ELONGATED MID LVL DEFORMATION ZONE HOLDING SE HALF THROUGH EARLY AFTN BFR BREAKING DOWN IN ASSOCN/W UPR TROUGH ACCELERATING EWD. LL CAA MAY STILL LEAD TO A MIX OF SNOW ON TAIL END OF PRECIP BUT W/SKIN TEMPS REMAINING WELL ABV FREEZING ACCUMULATIONS INSIGNIFICANT. MEANWHILE POST FNTL AIRMASS CONTS TO DRY NW AND WILL SPREAD SEWD THROUGH THE DAY W/EVENTUAL CLEARING LT AFTERNOON NW THROUGH EVENING SE AND GIVEN EXTRAPOLATION OF BACK EDGE TO PCPN SHIELD WILL DROP MENTION ALTOGETHER FAR NW. OTHERWISE WILL HOLD CLOSE TO GOING TEMPS FOR THE MOST PART GIVEN INTERVENTION HAS CAUSED MORE HARM THEN GOOD LAST TWO DAYS. LONG TERM... NEGATIVE HEIGHT ANOMALY IN THE GULF OF ALASKA THROUGH THE PERIOD WILL RESULT IN AN ACTIVE PATTERN DOWNSTREAM...WITH ONE DISTURBANCE POSSIBLY RESULTING IS SOME ACCUMULATING SNOW FRI INTO EARLY SAT AND ANOTHER SYSTEM BY MON NIGHT/TUE. THIS PATTERN DOES FAVOR OVERALL UPPER LEVEL TROUGHING IN THE EASTERN US WHICH WILL LIKELY RESULT IN BELOW NORMAL TEMPERATURES THROUGH THE MIDDLE OF NEXT WEEK. THU NIGHT - SAT AM: THE MAIN CONCERN CONTINUES TO BE THE PLACEMENT OF BAROCLINIC ZONE AND THE EVENTUAL TRACK OF A SFC LOW PROGGED TO TRACK ESE ALONG IT LATE THU NIGHT INTO FRI/FRI EVE. A SHRTWV WILL EJECT INTO THE CENTRAL/NORTHERN PLAINS AND INDUCE CYCLOGENESIS THU NIGHT NEAR/JUST SOUTH OF THE OMAHA AREA. THIS RELATIVELY WEAK SFC REFLECTION WILL THEN TRACK EAST INTO NORTHERN OR CENTRAL IN BY EARLY FRI EVE. FOLLOWED CLOSE TO PREVIOUS FCST WHICH MATCHED UP WELL WITH THE FARTHER NORTH 00Z OPERATIONAL GFS...NAM...AND SREF. HOWEVER...THE LATEST ECMWF AND GEM RUN ARE A LITTLE FARTHER SOUTH WITH BOUNDARY AND ACCUMULATING SNOW. SYSTEM IN QUESTION IS STILL OFFSHORE SO EXPECT DETAILS TO BECOME CLEARER WITH BETTER SAMPLING AS SHRTWV SLIDES INTO THE PAC NW BY WED EVE. TOP DOWN METHOD FROM GFS/NAM SOUNDINGS AND PROGGED PARTIAL THICKNESSES INDICATE ALL SNOW JUST NORTH OF THE 850H LOW TRACK AND RAIN SOUTH. AS FOR INITIAL THOUGHTS ON TIMING...THINK BAND OF PRECIP BREAKS OUT ACROSS E IA...N IL...AND S WI THU EVE AND TRACKS EAST INTO SRN MI AND POSSIBLY FAR NRN IN BY LATE THU NIGHT INTO FRI AM. THIS INITIAL BATCH OF PRECIP WILL DEVELOP IN RESPONSE TO THETA-E ADV WITH LL CONVERGENCE AT NOSE OF EXPECTED 35-50KT LL JET. ALSO...THE GFS AND NAM ARE REMAINING CONSISTENT IN SHOWING ROBUST FRONTOGENESIS MAINLY IN THE 850-700H LAYER WITH POTENTIAL NARROW BAND OF ACCUMULATING SNOW. EVEN IF BAND ASSOCIATED WITH LL FORCING ENDS UP JUST NORTH OF CWA THU NIGHT/FRI AM...STILL THINK CWA WILL GET INTO SOME RAIN/SNOW FRI AFTN/EVE WITH LARGE SCALE ASCENT PROVIDED BY SHRTWV AND ITS ASSOCIATED DEEPER MOISTURE/OMEGA. AS A RESULT...DECIDED TO CONTINUE WITH LIKELY SN POPS ALONG/NORTH OF ROUTE 6 06-18Z FRI AND CHC POPS FOR MIX SOUTH. AND CONTINUED WITH LIKELY POPS FRI AFTN EVERYWHERE FOR RAIN AND SNOW NORTH...AND ALL RAIN SOUTH. SOME LIGHT SNOW...POSSIBLY MIXED WITH RN IN THE EVE...WILL CONTINUE FRI NIGHT INTO SAT AM. KEPT WITH CHC POPS FOR THIS TIMEFRAME WITH SUBSEQUENT SHIFTS PROBABLY NEEDING TO BUMP POPS INTO LIKELY CATEGORY FOR AT LEAST FRI EVE. FIRST GUESS FOR TOTAL SNOW ACCUMULATION IN THE GRIDS IS 2-4 INCHES ALONG/NORTH OF ROUTE 6...AROUND AN INCH IN THE CENTRAL CWA...AND AN INCH OR LESS FAR SOUTH. SAT-TUE: SEVERAL WEAK DISTURBANCES IN NORTHWEST FLOW MAY BRING SOME VERY LIGHT PRECIP INTO THE REGION DURING THE SATURDAY THROUGH MONDAY TIMEFRAME. HOWEVER...WILL KEEP WITH DRY FCST AS TIMING THESE QUICK MOVING WAVES IS NEARLY IMPOSSIBLE THIS FAR OUT AND THAT ANY SNOW WILL BE BRIEF/LIGHT DUE TO THERE BEING LITTLE IF ANY MOISTURE TO WORK WITH. THE ONLY EXCEPTION WILL BE SNOW CHCS SAT AM WITH TROUGH AXIS SWINGING THROUGH. THE ECMWF AND GEM CONTINUE TO HINT AT A STRONG WAVE ROUNDING THE BASE OF THE TROUGH WITH A POTENTIAL WINTER STORM AFFECTING THE EASTERN SEABOARD. THIS WILL REINFORCE TROUGH IN PLACE AND KEEP TEMPERATURES WELL BELOW NORMAL THROUGH THE WEEKEND INTO THE FIRST PART OF NEXT WEEK. KEPT LOW CHC POPS IN FOR LATE MON NIGHT INTO TUE AS 00Z GUIDANCE REMAINS CONSISTENT IN DROPPING A CLIPPER-LIKE SYSTEM INTO THE GREAT LAKES. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR INZ026-027-032>034. MI...NONE. OH...FLOOD WATCH UNTIL 8 AM EDT THIS MORNING FOR OHZ016-024-025. LM...NONE. && $$ SHORT TERM...HOLSTEN LONG TERM...STEINWEDEL AVIATION...HOLSTEN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 732 AM CDT WED MAR 19 2008 .UPDATE...STILL A FEW SHOWERS OVER OUR EASTERN COUNTIES BUT THE SQUALL LINE HAS MOVED EAST OF OUR AREA AND THE TORNADO WATCH EXPIRED AT 7AM. SURFACE ANALYSIS HAS THE STRONG LOW BETWEEN GREENVILLE AND GREENWOOD. THE TEMPERATURE AT GREENWOOD AT 7AM WAS STILL 71F WHILE THE TEMPERATURE AT GREENVILLE DROPPED TO 61F. LOWER 50S WERE NOTED BACK OVER SOUTHEAST ARKANSAS THAT WILL FILTER INTO THE AREA IN THE WAKE OF THE COLD FRONT AS THE LOW MOVES NORTHEAST TODAY. HAVE ADJUSTED THE MAXIMUM TEMPERATURE FORECAST TO REFLECT CURRENT TEMPS ALONG WITH FALLING TEMPERATURES EXPECTED WITH THE FRONT TODAY. GRADIENT WINDS OVER THE DELTA REGION ARE EXPECTED TO REACH LOCAL LAKE WIND ADVISORY CRITERIA LATER THIS MORNING THROUGH THE EARLY AFTERNOON SO HAVE EXTENDED THE LAKE WIND ADVISORY TODAY NORTHWEST OF A WINNSBORO TO GRENADA LINE. THE UPPER LOW WAS NOTED ON SATELLITE IMAGERY MOVING UP INTO WESTERN ARKANSAS. THIS LOW WILL WEAKEN TODAY BUT BRING A FEW SHOWERS BACK INTO OUR NORTHERN COUNTIES LATER TODAY. DRIER AIR HAS MOVED INTO OUR SOUTHWEST ZONES AND SHOULD LIMIT RAIN CHANCES IN OUR SOUTHERN ZONES ONCE THE CURRENT MORNING ACTIVITY CLEARS OUT. UPDATES ARE POSTED. && .PREVIOUS DISCUSSION...SHORT TERM...TODAY THROUGH THURSDAY NIGHT...THE SQUALL LINE WAS NEARING THE I-55 CORRIDOR AT 330 AM AND STRONGEST FROM HIGHWAY 82 AND SOUTHWARD. OUR EASTERN COUNTIES WILL BE UNDER THE GUN DURING THE NEXT SEVERAL HOURS. THE LINE IS EXPECTED TO BE CLOSE TO THE MS/AL STATE LINE BY 7 AM ESSENTIALLY ENDING THE SEVERE WEATHER THREAT FOR OUR AREA. WATER VAPOR IMAGERY/RUC ANALYSIS SHOWS THE CLOSED UPPER LOW OVER THE RED RIVER VALLEY WHILE SURFACE ANALYSIS PLACES THE LOW OVER SOUTHEAST ARKANSAS. THE SURFACE LOW WILL TRACK TO THE NORTHEAST ACROSS NORTHEAST MISSISSIPPI TODAY WHILE THE CLOSED UPPER LOW OPENS UP AND SHIFTS EAST. WATER VAPOR IMAGERY IS ALSO SHOWING THE EXPECTED DRY SLOTTING WRAPPING UP AROUND THE EAST SIDE OF THE UPPER LOW...OVER OUR WESTERN ZONES. HOWEVER...REGIONAL RADARS ARE SHOWING A LINE OF SHOWERS ALONG THE TRAILING COLD FRONT BACK OVER WESTERN LOUISIANA SO WL MAINTAIN RAIN CHANCES THIS MORNING FOR THE FRONT. THE COLD FRONT IS EXPECTED TO BE EAST THE I-55 CORRIDOR BY NOON AND EAST OF OUR CWA BY LATE AFTERNOON. ALTHOUGH THE FRONT WILL BE TO OUR EAST...THE UPPER TROUGH AXIS AND ASSOCIATED CLOUD COVER WON`T SHIFT EAST UNTIL TONIGHT. THE WINDS BEHIND THE COLD FRONT WILL APPROACH LOCAL LAKE WIND ADVISORY CRITERIA FOR A COUPLE OF HOURS THIS MORNING OVER OUR DELTA REGION. WL HOLD OFF ISSUANCE FOR NOW AND REEVALUATE LATER. THUS WL ALLOW THE CURRENT LAKE WIND ADVISORY FOR THE WHOLE AREA TO EXPIRE AT 7 AM. HIGH PRESSURE WILL BUILD OVER OR CWFA FROM THE WEST TONIGHT INTO THURSDAY BEFORE SHIFTING EAST OF OUR CWFA THURSDAY NIGHT. THE COOLER AND DRIER AIR BEHIND THE FRONT WILL RESULT IN BELOW NORMAL TEMPERATURES THROUGH FRIDAY MORNING. LONG TERM...FRIDAY THROUGH WEDNESDAY...OVERALL MEDIUM RANGE MODELS ARE DRIER IN THE LONG TERM BUT MAINTAIN RAIN CHANCES FOR OUR AREA FOR SUNDAY INTO SUNDAY NIGHT. BY FRIDAY MORNING HIGH PRESSURE AT THE SURFACE WILL BE CENTERED OVER THE SOUTHEAST CONUS AND SLIDE EAST INTO THE ATLANTIC DURING THE DAY. OUR LOW LEVEL FLOW WILL VEER TO THE SOUTH BUT REMAIN LIGHT AND NOT WORK TO INCREASE MOISTURE MUCH BEFORE A DRY COLD FRONT MOVES THROUGH OUR CWFA SATURDAY. THE COLD FRONT IS EXPECTED TO MAKE IT TO THE GULF COAST BEFORE STALLING. HIGH PRESSURE CENTERED OVER THE GREAT LAKES REGION WILL BRIEFLY RIDGE SOUTH INTO OUR AREA INTO SUNDAY BEFORE SLIDING EAST AND ALLOWING A STRONGER DISTURBANCE TO MOVE INTO OUR REGION SUNDAY NIGHT. THERE AREA STRENGTH AND TIMING DIFFERENCES BETWEEN THE GFS AND THE ECMWF BUT A POTENT NORTHERN STREAM SHORTWAVE WILL DROP SOUTH OUT OF THE NORTHERN PLAINS AND DEEPEN A TROUGH OVER OUR REGION. THIS WILL BRING AN INCREASE IN RAIN CHANCES BY SUNDAY AFTERNOON AND LAST INTO SUNDAY NIGHT. THE ECMWF IS DEEPER AND A TAD FASTER THAN THE GFS WITH THIS FEATURE. MONDAY MORNING TEMPERATURES ARE EXPECTED TO DIP INTO THE LOWER 30S IN THE NORTH RESULTING IN PATCHY FROST. IF THE GFS TRENDS TOWARD THE ECMWF EVEN COLDER MORNING LOWS COULD BE REALIZED MONDAY MORNING. RIDGING SURFACE AND ALOFT WILL BUILD OVER OUR REGION MONDAY THROUGH WEDNESDAY RESULTING IN A RETURN TO DRY WEATHER AND A WARMING TREND TOWARD NEAR NORMAL TEMPERATURES. && .AVIATION...SQUALL LINE WILL MOVE EAST OVER THE EASTERN HALF OF MISSISSIPPI THROUGH 13Z BEFORE SHIFTING EAST INTO ALABAMA. OUTSIDE OF THUNDERSTORM AREAS...WIDESPREAD MVFR CEILINGS WILL PREVAIL TODAY. A TRAILING COLD FRONT WILL MOVE ACROSS THE AREA LATER TODAY WITH A FEW ADDITIONAL SHOWERS POSSIBLE MAINLY IN THE NORTH. AN UPPER LEVEL TROUGH AXIS WILL NOT SHIFT EAST ACROSS THE AREA UNTIL TONIGHT. BREAKS IN THE CLOUDS MAY OCCUR IN THE SOUTH TODAY BUT THE LOW CLOUDS WILL LIKELY HANG IN THE NORTH UNTIL THE UPPER TROUGH AXIS SHIFTS EAST. && .PRELIMINARY POINT TEMPS/POPS... JACKSON 69 41 70 42 / 20 0 0 0 MERIDIAN 71 42 69 38 / 61 0 0 0 VICKSBURG 67 41 69 42 / 16 0 0 0 HATTIESBURG 71 43 72 39 / 30 0 0 0 NATCHEZ 65 43 68 41 / 14 0 0 0 GREENVILLE 66 40 68 45 / 41 0 0 0 GREENWOOD 69 39 68 43 / 50 0 0 0 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...LAKE WIND ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR MSZ018-019- 025-026-034-035-040-041. LA...LAKE WIND ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR LAZ007>009- 015. AR...LAKE WIND ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR ARZ074-075. && $$ 22 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1127 AM EDT WED MAR 19 2008 .SYNOPSIS... LOW PRESSURE WILL MOVE FROM PENNSYLVANIA TO NEW ENGLAND THROUGH TONIGHT. RAIN, HEAVY AT TIMES, WILL SPREAD INTO NY AND PA AHEAD OF THE STORM. SNOW WILL FOLLOW ONCE THE STORM MOVES EAST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LOCAL RADARS SHOW LARGE HOLES IN PRECIP SHIELD FROM CNTRL NY THROUGH NORTHWEST PA TO CNTRL OHIO. BOTH 12Z NAM AND LATEST RUC INDICATE LIGHTER QPF THROUGH LATE AFTERNOON. ADJUSTED GRIDS/ZONES TO MENTION OCCASIONAL LIGHT RAIN FOR THE REMAINDER OF THE AFTERNOON. NO OTHER CHANGES. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... AS WE APPROACH LATE AFTERNOON AND EARLY EVENING, MODELS INDICATE THE ATMOSPHERE WILL DESTABILIZE FROM THE TWIN TIERS DOWN THROUGH THE WYOMING VALLEY. SOME OF THE MODEL SOUNDINGS PRODUCED MODERATELY UNSTABLE LI/S, BUT THESE WERE BASED ON UNREALISTICALLY HIGH DEW POINTS. WE MODIFIED UPSTREAM SOUNDINGS USING SFC TEMPS IN THE UPPER 40S TO LOWER 50S, AND DEW POINTS FROM 41F TO 45F. THIS PRODUCED LI/S FROM -2C TO +1C. K-INDICES ALSO SHOUTING CONVECTIVE POTENTIAL IN THIS REGION. GIVEN POSITION OF LLJ NOSE AND DEVELOPING INSTABILITY, WE HAVE ADDED CHC THUNDER FROM 22Z TO 6Z ALONG AND AHEAD OF COLD FRONT. WINDS OF 50-60 KTS FROM 3-5KFT SUGGEST STRONGER STORMS MAY PRODUCE VERY GUSTY WINDS. DOWNPOURS COULD BE PARTICULARLY TROUBLESOME IF TERRAIN IS ALREADY SATURATED. COLD AIR BEHIND COLD FRONT WILL CHANGE PRECIPITATION OVER TO SNOW FROM WEST TO EAST OVERNIGHT. WE HAVE INDICATED UP TO AN INCH OF SNOW OVER THE FAR WESTERN FORECAST AREA BY SUNRISE THURSDAY. PERSISTENT WRAP AROUND FORMS BEHIND STORM AS UL TROF ENERGY SITS OVERHEAD. FLOW IS FAVORABLE FOR LAKE ENHANCEMENT. A 1-2 INCH SNOW ACCUMULATION IS EXPECTED THURSDAY, WITH THE POSSIBILITY FOR UP TO 3 INCHES DOWNWIND OF LAKE ONTARIO. THIS PATTERN SLOWLY WEAKENS THROUGH FRIDAY MORNING. LOW PRESSURE MOVING THROUGH THE OHIO VALLEY WILL BRING ANOTHER POTENTIAL SNOW EVENT TO THE REGION LATE FRIDAY NIGHT. MAIN THREAT FOR SNOW ACCUMULATION WILL BE OVER SOUTHERN HALF OF FORECAST AREA. && .LONG TERM /SATURDAY THROUGH TUESDAY/... RELATIVELY LITTLE CHANGE TO EXISTING FORECAST. FAST MOVING SURFACE WAVE IS PROGGED TO PASS TO OUR SOUTH BY EARLY SATURDAY...WITH A CHANCE OF LIGHT RAIN OR SNOW ACROSS NORTHEAST PA AND SULLIVAN COUNTY NY. OTHERWISE...MOST OF THE REMAINDER OF THE WEEKEND LOOKS DRY...WITH A LARGE HIGH PRESSURE RIDGE FROM CANADA IN CONTROL. CONSIDERABLE UNCERTAINTY REMAINS FOR SUNDAY NIGHT AND MONDAY...WITH A POTENTIALLY SIGNIFICANT CYCLONE DEVELOPING NEAR THE EAST COAST. THE GFS KEEPS MOST...IF NOT ALL OF THE PRECIPITATION WITH THIS STORM SOUTH AND EAST OF OUR FORECAST AREA...WHILE THE EUROPEAN MODEL BRINGS SNOW TO MUCH OF CENTRAL NY/NORTHEAST PA...ALTHOUGH EVEN ITS SOLUTION IS FARTHER TO THE EAST THAN IT WAS YESTERDAY. FOR NOW...WE`LL KEEP IN THE CHANCE OF SNOW AREA-WIDE. FOR TUESDAY AND WEDNESDAY...A COLD NORTHWEST FLOW WILL BRING THE CHANCE OF LAKE-EFFECT SNOW SHOWERS. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... MVFR TO IFR INDICATED THROUGH MOST OF TONIGHT...AS RAIN AND LOWER CEILINGS IMPACT THE REGION. SOUTH TO SOUTHEAST WINDS WILL ALSO PREVAIL AT THE SURFACE...WITH LOW-LEVEL WIND SHEAR LOOKING TO BECOME MORE OF A CONCERN THIS AFTERNOON. WINDS WILL SWING AROUND TO THE NORTHWEST LATER THIS EVENING...UPON PASSAGE OF A STRONG COLD FRONT. RAIN SHOULD ALSO BEGIN TO MIX WITH SNOW AFTER ABOUT 09Z. OUTLOOK... THUR/THUR NIGHT...OCCASIONAL SNOW SHOWERS...WHICH COULD CAUSE MVFR TO BRIEF IFR RESTRICTIONS. BEST CHANCE WILL BE SYR-ITH-BGM- RME TERMINALS. GUSTY 15-25 KT NORTHWESTERLY WINDS EXPECTED. FRIDAY THROUGH SUNDAY...VFR CONDITIONS EXPECTED. STILL A POSSIBILITY FOR A FEW LAKE EFFECT SNOW SHOWERS NEAR SYR TERMINAL ON FRIDAY. SNOW SHOWERS COULD CAUSE MVFR TO BRIEF IFR RESTRICTIONS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR PAZ038>040-043-044- 047-048-072. NY...FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR NYZ009-015>018- 022>025-036-037-044>046-055>057-062. && $$ SYNOPSIS...DJP NEAR TERM...RRM SHORT TERM...DJP LONG TERM...MLJ AVIATION...JML/MLJ ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE UPTON NY 344 PM EDT WED MAR 19 2008 .SYNOPSIS... A WARM FRONT WILL MOVE NORTHWARD...FOLLOWED QUICKLY BY A COLD FRONT TONIGHT. LOW PRESSURE WILL LIFT NORTH AND EAST LATE TONIGHT AND THURSDAY. A STRONG WESTERLY FLOW WILL PREVAIL THURSDAY AND FRIDAY AS THE LOW SETTLES TO THE NORTH. A WEAK WAVE OF LOW PRESSURE WILL PASS JUST SOUTH OF THE AREA SAT. LOW PRESSURE PASSES OFF THE MID ATLANTIC COAST SUN NIGHT AND MON...FOLLOWED BY HIGH PRES INTO TUE. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... NORTHERN AND SOUTHERN BRANCHES PHASE THIS EVENING. PLENTY OF GULF MOISTURE GETTING SWEPT NORTHWARD ALONG EASTERN SEABOARD...SEEN NICELY ON WATER VAPOR IMAGERY. OCCASIONAL SHOWERS TO PREVAIL THROUGH TONIGHT. WARM FRONT KNOCKING ON OUR DOORSTEP...AND THIS FRONT SHOULD MOVE THROUGH AT LEAST HALF TO MOST OF THE CWA...FROM SOUTHWEST TO NORTHEAST AHEAD OF CONSOLIDATING LOW PRESSURE OVER CENTRAL PA. WARM SECTOR SHOULD BE BRIEF THOUGH AS THIS LOW PRESSURE DRAGS A COLD FRONT THROUGH AFTER MIDNIGHT. STILL SOME MODEL TIMING DIFFERENCES...BUT SFC COLD FRONT ON ALL MODELS DEPICTED TO BE EAST OF THE AREA BY MORNING. STRONG FRONTAL FORCING...MARGINAL INSTABILITY ALOFT AND FAVORABLE JET DYNAMICS WILL AID IN THE DEVELOPMENT OF ISOLATED THUNDERSTORMS ALONG AND AHEAD OF THE FRONT OVERNIGHT. ALWAYS RUN THE RISK OF MIXING SOME OF THE STRONG WINDS DOWN (LOW LEVEL JET) IN ANY HEAVIER CONVECTION. THIS HAS HAPPENED SEVERAL TIMES THIS WINTER. THIS WOULD BE IN ADDITION TO GRADIENT SOUTHERLY FLOW. TEMPS SHOULD SLOWLY RISE THROUGH THE OVERNIGHT...BEFORE DROPPING BACK A FEW DEGREES TOWARD MORNING BEHIND THE FRONT. AS FOR RAINFALL...COULD SEE LOCAL HEAVY DOWNPOURS...BUT ADDITIONAL AREAL RAINFALL OF A HALF TO THREE QUARTERS OF AN INCH POSSIBLE. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... MID AND UPPER LEVEL TROUGH MOVE THROUGH EARLY THURSDAY MORNING. THIS IS A FEW HOUR LAG BEHIND SFC FRONT. A FEW SHOWERS ARE POSSIBLE AS THIS MOVES THROUGH. THEN...HIGHLY ANOMALOUS UPPER AND SFC LOW SETTLE OVER CANADIAN MARITIMES BEFORE SLOWLY RETROGRADING INTO SOUTHEAST CANADA THURSDAY AND FRIDAY. THE SFC LOW DEEPENS THROUGH THE DAY THURSDAY...BEFORE WEAKENING SLIGHTLY FRIDAY. SOME MODEL DIFFERENCES WITH REGARD TO THE STRENGTH OF THIS LOW...WITH NAM AND GFS STRONGER AT APPROX 974 HPA BY THU EVENING. EC/UKMET/GGEM NOT AS DEEP...BUT DEEP NONETHELESS. VERY TIGHT PRESSURE GRADIENT PREVAILS THROUGH THIS TIME FRAME. AS SUCH...WEST/NW WINDS WILL REMAIN STRONG THROUGH THE PERIOD...AND WE COULD EVEN SEE OUR STRONGEST WINDS OCCUR LATE IN THE DAY THURSDAY INTO THURSDAY EVENING. A FEW CLOUDS FROM LAKE MOISTURE AND CYCLONIC FLOW...BUT DEEP NW FLOW UP THE COLUMN WILL KEEP IT DRY. AS THE UPPER LOW PIVOTS NORTHWESTWARD FRIDAY NIGHT...WEAK UPPER WAVE/SFC LOW APPROACH IN FAST WEST FLOW. SOME MID AND HIGH CLOUDS MOVE IN FRIDAY NIGHT...AND WE COULD SEE SOME LIGHT PRECIPITATION BY LATE AT NIGHT/EARLY SATURDAY. AGAIN...THIS IS EXPECTED TO BE LIGHT...AND MAINLY TO THE SOUTH. COULD SEE SOME LIGHT SNOW OR A RAIN/SNOW MIX. DRYING MOVES IN FROM THE NORTH BY SAT AFTN. TEMPS: FOLLOWED A MOS BLEND THROUGH THE PERIOD...ALTHOUGH I DISCOUNTED SOME OF THE COOLER FWC NUMBERS AS THEY SEEMED TO BE AN OUTLIER WITH MET/MAV AND 2 M MODEL TEMPS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... WEAK LOW PRESSURE WILL PASS TO THE SOUTH ON SAT...WITH HIGH PRESSURE BUILDING INTO THE REGION SUNDAY INTO MONDAY. IN THE MONDAY THROUGH WEDNESDAY PERIOD...MODELS INDICATE CYCLOGENESIS OFF THE EASTERN SEABOARD BUT TRACK OF THIS POTENTIALLY POTENT SYSTEM REMAINS UNCERTAIN. RECENT ECMWF RUNS HAVE SHOWN A LATE SEASON SNOWSTORM IMPACTING THE MID ATLANTIC AND NORTHEAST REGIONS. HOWEVER..THE LATEST 12Z ECMWF RUN HAS BACKED OFF THIS SCENARIO IN FAVOR OF A TRACK FURTHER OFF THE COAST. LATEST 12Z GFS AND CANADIAN RUNS ALSO DEPICT A MORE OFFSHORE TRACK WHICH WOULD RESULT IN MINIMAL PRECIPITATION AMOUNTS ACROSS THE TRI-STATE AREA. THERE IS ALSO MODEL DISPARITY IN THE TIMING AND SPEED OF THIS SYSTEM...WITH ECMWF MORE PROGRESSIVE AND GFS SLOWER. BY WEDNESDAY...THE COASTAL LOW LIFTS NORTHEAST INTO THE CANADIAN MARITIMES LEAVING SLIGHTLY BELOW AVERAGE TEMPERATURES IN ITS WAKE. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... IFR CONDITIONS WEDNESDAY AFTERNOON WITH LOW CIGS...SCATTERED SHOWERS AND FOG AT AREA TERMINALS AS WARM FRONT APPROACHES FROM THE SOUTH. IMPROVEMENT IN CIGS/VSBYS WILL BE DICTATED BY HOW FAR NORTH THE FRONT PROGRESSES TODAY AND HOW QUICKLY IT MOVES. GFS AND ETA MOS GUIDANCE KEEP LIFR/IFR CIGS IN PLACE UNTIL 09Z THURSDAY (WHEN COLD FRONT PASSES) WHILE RUC AND GFS BUFKIT ANALYSIS INDICATE MVFR CONDS AFTER 02Z. WROTE HIGH END IFR CONDS INTO 18Z TAFS UNTIL 02Z...AND WILL MONITOR PROGRESSION OF FRONT THIS AFTERNOON. EXPECT A ESE TO SE FLOW 10 TO 15 KT TO THE NORTH OF THE WARM FRONT...WITH A S FLOW INCREASING TO 15 TO 20 KT TO THE SOUTH OF THE FRONT. LOW LEVEL WIND PROFILE STRENGTHENS AFTER ABOUT 20/02Z. LOOK FOR A 50 TO 60 KT SOUTHWEST FLOW AT 1500-2000 FT. CONTINUED MENTION OF WS IN THE TAFS. COLD FROPA TONIGHT EXPECTED TO RANGE BETWEEN 08-12Z FROM WEST TO EAST...LIKELY ACCOMPANIED OR IMMEDIATELY PRECEDED BY A LINE OR BROKEN LINE OF CONVECTION. THERE COULD POSSIBLY BE A RUMBLE OF THUNDER...BUT CONFIDENCE IS TOO LOW TO INCLUDE IN TAFS AT THIS TIME. A STRONG AND GUSTY WEST TO NORTHWEST FLOW WILL DEVELOP BEHIND THE FRONT...ALONG WITH A RETURN TO VFR CONDITIONS. OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...VFR CONDITIONS WITH GUSTY W TO NW WINDS CONTINUE THU INTO FRI. WEAK LOW PRESSURE WILL PASS TO THE SOUTH ON SAT...BUT NO CIG/VSBY ISSUES ARE EXPECTED ATTM. HIGH PRESSURE BUILDS IN SUNDAY AND MONDAY. && .MARINE... WARM FRONT EXPECTED TO MAKE IT NORTHWARD THROUGH ALL AREA WATERS THIS EVENING...WITH LOW PRESSURE PASSING TO THE NORTH LATE TONIGHT INTO TOMORROW MORNING...DRAGGING A COLD FRONT THROUGH THE WATERS DURING THIS TIME. WILL KEEP SCA TONIGHT...TRANSITIONING TO GALES TOMORROW AND TOMORROW NIGHT...ALTHOUGH THERE MAY BE A PERIOD DURING THIS EVENING WHEN GUSTS ARE NOT REACHING 25 KT. SEAS ON THE OCEAN ARE ALREADY AT 6-7 FT...AND SHOULD REMAIN AT SCA LEVELS FOR MOST...IF NOT ALL...OF THIS EVENING. WINDS PICK UP AFTER MIDNIGHT AS COLD FRONT APPROACHES AND PASSES THROUGH. MODELS INDICATING A 60-70KT LLJ PRECEDING THE FRONT...HOWEVER A STRONG LOW LEVEL INVERSION SHOULD REMAIN IN PLACE UNTIL FROPA. IT WOULD LIKELY TAKE STRONGER CONVECTION TO MIX DOWN STRONG GUSTS...AND CONVECTION IS EXPECTED TO BE ISOLATED...BUT WILL MENTION OCCASIONAL GALE FORCE GUSTS IN CWF LATE AT NIGHT. GALE FORCE GUSTS ACCOMPANIED BY WNW SUSTAINED WINDS OF 20-30 KTS THEN EXPECTED THROUGH THURSDAY. SEAS ON THE OCEAN EXPECTED TO BUILD UP TO 7-10 FT. PRESSURE GRADIENT REMAINS TIGHT OVER THE AREA ON THURSDAY NIGHT AS HIGH PRESSURE BUILDS IN BEHIND THE STORM MOVING FARTHER OFF TO THE NORTHEAST...STRENGTHENING AS IT DOES SO. GALES THEREFORE CONTINUE THROUGH THE NIGHT...AND LIKELY INTO FRIDAY AS WELL. WILL ALLOW MID SHIFT TO EXTEND GALES INTO FRIDAY WHERE NECESSARY. SUB SCA CONDITIONS MAY NOT RETURN UNTIL SOMETIME LATE FRIDAY NIGHT INTO SATURDAY MORNING. GENERALLY QUIET CONDITIONS WILL DOMINATE SATURDAY NIGHT INTO SUNDAY AS HIGH PRESSURE BUILDS INTO THE AREA. A COASTAL LOW WILL BEGIN TO IMPACT THE AREA ON MONDAY...RESULTING IN INCREASING NE FLOW AND BUILDING SEAS. CONDITIONS WILL LIKELY REACH SCA CRITERION LATER ON MONDAY WITH GALE FORCE WINDS POSSIBLE. && .HYDROLOGY... MUCH OF THE AREA HAS RECEIVED A HALF TO AN INCH OF QPF...AND ANOTHER HALF TO THREE QUARTERS OF AN INCH IS POSSIBLE. SOME ISOLATED HEAVIER AMOUNTS POSSIBLE AHEAD OF COLD FRONT OVERNIGHT. RIVERS AND STREAMS ARE SHOWING MINOR TO MODERATE RISES THROUGH THE PERIOD. THE GROUND SHOULD BE ABLE TO ABSORB SOME RUNOFF...AND SOME RIVERS AND STREAMS HAVE BEEN ABLE TO RETURN TO NORMAL...SO NO RIVER/STREAM FLOODING IS ANTICIPATED AT THIS TIME. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ330-335- 338-340-345-350-353-355-370. GALE WARNING FROM 6 AM THURSDAY TO 6 AM EDT FRIDAY FOR ANZ330- 335-338-340-345-350-353-355. && $$ SYNOPSIS...PW NEAR TERM...PW SHORT TERM...PW LONG TERM...NV/MS AVIATION...KS/JC MARINE...JC/NV/MS HYDROLOGY...PW ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE UPTON NY 244 PM EDT WED MAR 19 2008 .SYNOPSIS... A WARM FRONT APPROACHING THE AREA FROM THE SOUTH WILL WORK SLOWLY NORTHWARD THIS AFTERNOON...PASSING THROUGH THE TRI-STATE AREA DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. THERE IS A CHANCE THAT THE WARM FRONT MAY NOT CLEAR NORTHERN PORTIONS OF THE LOWER HUDSON VALLEY AND INTERIOR SOUTHWEST CONNECTICUT. THIS FRONT IS PART OF A MUCH LARGER FRONTAL SYSTEM ENCOMPASSING THE OHIO AND TENNESSEE VALLEYS. SEVERAL WAVES OF LOW PRESSURE ALONG THIS BOUNDARY WILL CONSOLIDATE INTO ONE AREA OF LOW PRESSURE OVER CENTRAL PA TONIGHT. AS THIS LOW LIFTS NORTH AND EAST OF THE AREA TONIGHT...A STRONG COLD FRONT WILL PUSH THROUGH LATE. A STRONG WESTERLY FLOW WILL FOLLOW FOR THU AND FRI AS THE DEEPENING LOW BECOMES NEARLY STATIONARY OVER THE CANADIAN MARITIMES. A WEAK WAVE OF LOW PRESSURE WILL PASS SOUTH OF THE AREA ON SAT...FOLLOWED BY HIGH PRESSURE BUILDING FROM CENTRAL CANADA ON SUN. LOW PRESSURE PASSES OFF THE MID ATLANTIC COAST SUN NIGHT AND MON...FOLLOWED BY HIGH PRES INTO TUE. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... RADAR TRENDS SUGGEST LESS ORGANIZED RAIN...BUT STILL WIDESPREAD COVERAGE UPSTREAM. OCCASIONAL RAIN ANTICIPATED AS AIR GETS FORCED OVER SURFACE WARM FRONT...WHICH SITS JUST TO OUR SOUTH. IN ANY BREAKS...COULD OBSERVE LIGHT RAIN/DRIZZLE. ALWAYS HARD TO FORECAST THE EXTENT OF NORTHWARD PROGRESSION OF THESE WARM FRONTS THIS TIME OF YEAR...BUT IT DOES APPEAR THAT THE FRONT SHOULD MOVE ACROSS CSTL SECTIONS BY LATE THIS AFTERNOON AS LOW PRESSURE MOVES TOWARD PA. MODEL CONSENSUS STILL PLACES LOW PRES OVER N CENTRAL PA WITH A PRESSURE AROUND 992 MB. A STRENGTHENING LOW-LEVEL SOUTHERLY JET TO THE EAST OF THE SYSTEM IS THE MAIN IMPETUS TO PUSH THE WARM FRONT TO THE NORTH OF THE TRI- STATE AREA. AREAS OF FOG REMAIN IN THE FORECAST AHEAD OF THE FRONT...AS USUALLY OCCURS. COULD BE DENSE IN SPOTS. TEMPS WILL BE SLOW TO RISE WITH THE CLOUD COVER AND RAINFALL. LATE DAYTIME HIGHS WILL BE IN THE UPPER 40S TO AROUND 50 AND WILL RISE A FEW MORE DEGREES INTO THE EVENING HOURS FOLLOWING THE WARM FRONTAL PASSAGE. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... PCPN WILL BECOME MORE DISJOINTED AND UNORGANIZED DURING THE LATE AFTERNOON AND EARLY EVENING HOURS IN THE WARM SECTOR. HOWEVER...AS LOW PRESSURE LIFTS TO THE NE AND UP INTO NEW ENGLAND...ITS TRAILING COLD FRONT WILL MOVE THROUGH BETWEEN 06Z AND 10Z. STRONG FRONTAL FORCING...MARGINAL INSTABILITY AND FAVORABLE JET DYNAMICS WILL PRODUCE WIDESPREAD SHOWERS/ISOLATED THUNDERSTORMS ALONG AND AHEAD OF THE FRONT OVERNIGHT. SHOULD SURFACE BASED INSTABILITY BECOME MORE PRONOUNCED WITH A WARMER BOUNDARY LAYER THIS EVENING... CONCERN FOR STRONG THUNDERSTORMS MAY ARISE. HOWEVER...CURRENT MODEL SOUNDINGS DO NOT SUPPORT SUCH A SCENARIO. RAINFALL AMOUNTS ASSOCIATED WITH THE COLD FRONTAL BAND ARE EXPECTED TO BE BETWEEN ONE-QUARTER TO ONE-HALF INCH WITH TOTAL QPF FROM THE EVENT BETWEEN ONE AND ONE ONE HALF INCHES. THE 00Z NAM AND GFS DIFFERED BY ABOUT 6 HR WITH THE COLD FRONTAL TIMING...WITH THE GFS BEING THE FASTER SOLUTION. BOTH THE 21Z SREF AND 00Z GFES SUPPORTED A COMPROMISE BETWEEN THE TWO SOLUTIONS. FOLLOWING THE COLD FRONTAL PASSAGE...A STRONG W/NW FLOW ENSUES THU INTO FRI AS DEEPENING LOW PRESSURE BECOMES NEARLY STATIONARY OVER THE CANADIAN MARITIMES. WINDS ON THU LOOK TO BE JUST BELOW WIND ADVISORY CRITERIA. HOWEVER...A STRONG ISALLOBARIC SURGE BEHIND THE COLD FRONT COULD BRIEFLY PRODUCE WINDS MEETING ADVISORY CRITERIA. CONFIDENCE FOR SUCH A SCENARIO IS NOT HIGH ENOUGH AT THIS TIME TO WARRANT THE ISSUANCE OF AN ADVISORY. CYCLONIC FLOW AND RESIDUAL MOISTURE ON THU WILL BE OFFSET BY A STRONG DOWNSLOPE COMPONENT WITH SKIES CLEARING BY AFTERNOON. EXPECTING NEAR NORMAL TEMPS THROUGH THE PERIOD. THERE ARE NO BIG DIFFERENCES IN MOS NUMBERS...SO WILL FOLLOW A BLEND. && .LONG TERM /SATURDAY THROUGH TUESDAY/... INITIALLY...STRONG LOW PRESSURE OVER THE CANADIAN MARITIMES AND A HIGH PRESSURE RIDGE NOSING DOWN INTO THE AREA IN ITS WAKE FRI NIGHT THROUGH SUNDAY SHOULD SUPPRESS A WEAK LOW MOVING EAST FROM THE PLAINS STATES TOWARD THE OH/TN VALLEYS AND THE MID ATLANTIC REGION ON SAT. TEMPS WILL RUN SLIGHTLY BELOW NORMAL. PER HPC...UNCERTAINTY INCREASES FROM SUNDAY AND BEYOND AS MODEL GUIDANCE SHOWS A WIDE ARRAY OF POTENTIAL SOLUTIONS AND RELATIVELY POOR RUN TO RUN CONTINUITY...AND IS STILL HAVING TROUBLE RESOLVING HOW QUICKLY TO BRING PACIFIC ENERGY ASSOCIATED WITH A DEEP NE PACIFIC CLOSED LOW INTO NORTH AMERICA...AND HOW AMPLIFIED THIS ENERGY WILL BE. AS A RESULT THIS FORECAST WILL REFLECT PRELIMINARY HPC GUIDANCE WHICH IS BASED ON A BLEND OF THE 18/00Z ECMWF...00Z ECMWF ENSEMBLE MEAN...AND THE 17/12Z ECMWF...WHICH DEPICTS LOW PRESSURE DEVELOPING OVER THE SOUTHEAST STATES ON SUNDAY...THEN MOVING OFFSHORE NEAR CAPE HATTERAS EARLY MON MORNING AND HEADING NE TOWARD THE CANADIAN MARITIMES LATER MON. THIS TRANSLATES TO CHANCE POP SUN NIGHT/MON...WITH TEMPS COLD ENOUGH FOR WET SNOW OVER THE INTERIOR MAINLY LATE SUN NIGHT/EARLY MON MORNING. A SLIGHT CHANCE FOR RAIN/SNOW SHOWERS IN CYCLONIC FLOW ON THE BACK SIDE OF THIS LOW SHOULD CONTINUE FOR MON NIGHT/EARLY TUE MORNING...THEN DRY WX EXPECTED FOR THE REST OF TUE...WITH TEMPS STILL SLIGHTLY BELOW NORMAL. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... IFR CONDITIONS WEDNESDAY AFTERNOON WITH LOW CIGS...SCATTERED SHOWERS AND FOG AT AREA TERMINALS AS WARM FRONT APPROACHES FROM THE SOUTH. IMPROVEMENT IN CIGS/VSBYS WILL BE DICTATED BY HOW FAR NORTH THE FRONT PROGRESSES TODAY AND HOW QUICKLY IT MOVES. GFS AND ETA MOS GUIDANCE KEEP LIFR/IFR CIGS IN PLACE UNTIL 09Z THURSDAY (WHEN COLD FRONT PASSES) WHILE RUC AND GFS BUFKIT ANALYSIS INDICATE MVFR CONDS AFTER 02Z. WROTE HIGH END IFR CONDS INTO 18Z TAFS UNTIL 02Z...AND WILL MONITOR PROGRESSION OF FRONT THIS AFTERNOON. EXPECT A ESE TO SE FLOW 10 TO 15 KT TO THE NORTH OF THE WARM FRONT...WITH A S FLOW INCREASING TO 15 TO 20 KT TO THE SOUTH OF THE FRONT. LOW LEVEL WIND PROFILE STRENGTHENS AFTER ABOUT 20/02Z. LOOK FOR A 50 TO 60 KT SOUTHWEST FLOW AT 1500-2000 FT. CONTINUED MENTION OF WS IN THE TAFS. COLD FROPA TONIGHT EXPECTED TO RANGE BETWEEN 08-12Z FROM WEST TO EAST...LIKELY ACCOMPANIED OR IMMEDIATELY PRECEDED BY A LINE OR BROKEN LINE OF CONVECTION. THERE COULD POSSIBLY BE A RUMBLE OF THUNDER...BUT CONFIDENCE IS TOO LOW TO INCLUDE IN TAFS AT THIS TIME. A STRONG AND GUSTY WEST TO NORTHWEST FLOW WILL DEVELOP BEHIND THE FRONT...ALONG WITH A RETURN TO VFR CONDITIONS. OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...VFR CONDITIONS WITH GUSTY W TO NW WINDS CONTINUE THU INTO FRI. WEAK LOW PRESSURE WILL PASS TO THE SOUTH ON SAT...BUT NO CIG/VSBY ISSUES ARE EXPECTED ATTM. HIGH PRESSURE BUILDS IN SUNDAY AND MONDAY. && .MARINE... A SMALL CRAFT ADVISORY WILL BE IN EFFECT FOR ALL WATERS THIS AFTERNOON AND TONIGHT. EXPECT TO SEE WIND GUSTS UP TO 25 KT TODAY AND OCCASIONAL GUSTS TO 30-35 KT TONIGHT. SEAS ON THE OCEAN WILL ALSO BE ROUGH. GALE WARNINGS WILL BE RAISED FOR ALL WATERS FOR THURSDAY AND THURSDAY NIGHT. ONCE THE COLD FRONT PUSHES THROUGH...A VERY STRONG WEST FLOW WILL DEVELOP AS THE PRESSURE GRADIENT TIGHTENS BETWEEN THE DEPARTING LOW AND APPROACHING HIGH PRESSURE. VERY HIGH CONFIDENCE EXISTS FOR THE PERSISTENCE OF GALE FORCE WIND GUSTS OVER ALL WATERS THU AND THU NIGHT. THEREAFTER...SCA CONDITIONS ARE LIKELY TO CONTINUE INTO FRI NIGHT ON ALL WATERS...AND ON THE OCEAN THROUGH SAT NIGHT...AS MODERATE NW FLOW CONTINUES. QUIET CONDITIONS FOLLOW WITH HIGH PRESSURE OVERHEAD ON SUNDAY...WHICH THEN GRADUALLY GIVES WAY TO APPROACHING LOW PRESSURE SUNDAY NIGHT. INCREASING NE-E FLOW SHOULD RESULT IN BUILDING SEAS SUNDAY NIGHT...BUT REMAINING BELOW SCA THRESHOLDS. && .HYDROLOGY... A COMPLEX WEATHER SYSTEM WILL IMPACT THE LOCAL AREA TODAY INTO TONIGHT...RESULTING IN 1 TO 1 1/2 INCHES OF RAINFALL WITH LOCALLY HIGHER AMOUNTS POSSIBLE BY THU MORNING. THE HEAVIEST RAINS WILL COME IN TWO INSTALLMENTS...WITH THE WARM FRONT INTO EARLY THIS AFTERNOON...THEN WITH THE COLD FRONTAL PASSAGE OVERNIGHT. RIVERS AND STREAMS ARE SHOWING MINOR TO MODERATE RISES THROUGH THIS PERIOD. THE GROUND SHOULD BE ABLE TO ABSORB SOME RUNOFF...AND SOME RIVERS AND STREAMS HAVE BEEN ABLE TO RETURN TO NORMAL...SO NO RIVER/STREAM FLOODING IS ANTICIPATED AT THIS TIME. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ330-335- 338-340-345-350-353-355-370. GALE WARNING FROM 6 AM THURSDAY TO 6 AM EDT FRIDAY FOR ANZ330- 335-338-340-345-350-353-355. && $$ ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 152 PM EDT WED MAR 19 2008 .SYNOPSIS... A LOW PRESSURE SYSTEM OVER THE LOWER MISSISSIPPI VALLEY WILL TRACK NORTHEAST INTO SOUTHERN NEW YORK STATE TODAY AND TONIGHT...AND OFF THE NORTHERN NEW ENGLAND COAST BY THURSDAY. WINDY AND COLDER CONDITIONS WILL FOLLOW IN THE WAKE OF THIS STORM SYSTEM FOR THURSDAY AND FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... BUSY MORNING...WITH A SECOND UPDATE EARLY THIS AFTERNOON. WE CANCELED THE WINTER STORM WARNINGS FOR NRN WASHINGTON AND SOUTHEASTERN WARREN COUNTIES. THE REMAINING WINTER ADVISORIES WERE ALLOWED TO EXPIRE. SOME POCKETS OF FREEZING RAIN/SLEET WILL CONTINUE PORTIONS OF THE NRN BERKS AND FOOTHILLS OF THE ADIRONDACKS. MADIS/METARS AROUND THE AREA SHOW TEMPS SLOWLY WARMING INTO THE MID 30S OVER PORTIONS OF THE NRN TIER. WE HAD A REPORT OF SLEET AND FREEZING RAIN STILL ONGOING IN NRN WARREN COUNTY. ELEVATED FREEZING RAIN LOOKS TO BE STILL ONGOING OVER WINDHAM COUNTY. LOCATIONS LIKE KGFL HAVE RISEN ABOVE FREEZING. THE TREND WILL BE FOR ALL LOCATIONS TO GET ABOVE FREEZING IN THE MID AFTERNOON...AS THE MAIN WARM FRONT LIFTS NORTHEAST FROM PA. THE REGIONAL RADAR TRENDS ARE SHOWING A BIT OF A LULL IN THE PCPN W/SW OF ERN NY. WE WILL CONTINUE WITH THE PERIODS OF RAIN PHRASING FOR THE AFTERNOON. FOR THE MOST PART...ITS HAS BEEN LIGHT WITH TOTAL QPF ACROSS THE REGION RANGING FROM A FEW TENTHS TO A THIRD OF AN INCH THUS FAR. THE 13KM RUC SHOWS THE FIRST OF A SERIES OF WAVES MOVING N/NE FROM OH VALLEY. THE QG LIFT WILL INCREASE IN THE LATE PM FROM THE STRONG LOW LEVEL CONVERGENCE TO THE WAVE. WE STILL BELIEVE SOME SCT TSRAS MAYBE BE POSSIBLE WITH SHOWALTER VALUES 0 TO -2C IN THE 22Z TO 06Z TIME FRAME. FLOOD WATCH CONTINUES WITH 1-2" OF LIQUID EQUIVALENT POSSIBLE BY 12Z THU. THE WINTER STORM WARNING CONTINUES FOR THE SRN ADIRONDACKS WITH 6-12 INCHES POSSIBLE BY FRIDAY MORNING. THIS WARNING WILL BE FURTHER ADDRESSED THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... TONIGHT...PERIODS OF RAIN...HVY AT TIMES...WILL CONTINUE THROUGH MIDNIGHT. IN ADDITION...AS ELEVATED INSTABILITY MOVES NE AHEAD OF SFC LOW...SOME THUNDER IS ALSO POSSIBLE...AND THUS HAVE INCLUDED MENTION FOR AREAS S OF THE MOHAWK RIVER...INTO EXTREME SOUTHERN VT. WILL NEED TO WATCH FOR POSSIBLE STRONGER THUNDERSTORMS ACROSS THE MID HUDSON VALLEY INTO NW CT LATER THIS EVENING UNTIL SHORTLY AFTER MIDNIGHT...AS STRONG LOW LEVEL WINDS COULD EASILY BE PROPELLED DOWNWARD WITHIN ANY DEEPER CONVECTIVE ELEMENTS...ESP SOUTH OF THE WARM FRONT. THE LOW SHOULD THEN TRACK ACROSS SE AREAS AROUND/JUST AFTER MIDNIGHT...AND TOWARD THE NEW ENG COAST BY DAYBREAK. THIS TRACK WILL ALLOW COLDER AIR TO SURGE E/SE AFTER MIDNIGHT...CHANGING THE RAIN INTO SNOW FOR HIGHER ELEVATIONS OF THE ADIRONDACKS...WHERE SEVERAL INCHES OF ACCUM IS POSSIBLE BY THU AM. ELSEWHERE...RAIN SHOWERS MAY CHANGE TO SNOW SHOWERS BY DAYBREAK...ESP FOR HIGHER ELEVATIONS. TEMPS TONIGHT WILL CONTINUE TO RISE UNTIL AROUND MIDNIGHT...THEN SHOULD FALL SHARPLY. SOME REGIONS OF THE MID HUDSON VALLEY AND NW CT COULD ACTUALLY RISE INTO THE MID 50S...WITH MID/UPPER 40S EVEN POSSIBLE INTO THE CAPITAL REGION...BEFORE THE COLDER AIR RETURNS LATER TONIGHT...WITH MINS OCCURRING AROUND 12Z. THU-THU NT...STRONG OROGRAPHIC LIFT...COMBINED WITH ENHANCED LOW LEVEL INSTABILITY/MOISTURE FROM LAKES WILL PROMOTE FREQUENT SNOW SHOWERS ACROSS THE ADIRONDACKS/WESTERN MOHAWK VALLEY...AND INTO SOUTHERN VT FOR THU-THU NT. THIS WILL LEAD TO SIGNIFICANT ACCUMS ACROSS PORTIONS OF NORTHERN HERKIMER/HAMILTON COS...WHERE WARNINGS REMAIN IN EFFECT UNTIL FRI AM. ELSEWHERE...SCATTERED SNOW SHOWERS WILL CONTINUE...WITH PERHAPS SOME RAIN MIXED IN ACROSS VALLEY LOCALES. THE BIGGER STORY OUTSIDE OF THE WINTER STORM WARNING AREA WILL BE THE STRONG/GUSTY WNW WINDS...WHICH MAY REACH OR EXCEED ADVISORY LEVELS. WE HAVE HELD OFF ON ANY WIND ADV THUS FAR...BUT MAY NEED TO ISSUE THIS WITH SUBSEQUENT FORECASTS. OTHERWISE...GENERALLY WENT WITH MAV/MET MOS BLEND FOR MAX TEMPS...EXCEPT SLIGHT WARMINER FOR THU NT MINS...AS CLOUDS AND WIND SHOULD KEEP TEMPS SLIGHTLY ABOVE TEMPS SUGGESTED BY MOS. FRI-FRI NT...STILL WINDY ON FRI...WITH LINGERING SNOW SHOWERS ACROSS NORTHERN AREAS. OTHERWISE...EXPECT MOSTLY CLEAR CONDITIONS...WITH DIMINISHING WINDS FOR FRI NT. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... ON SATURDAY...A WEAK CLIPPER MOVES FROM OHIO TO THE DELMARVA AND INTO THE ATLANTIC AND THEN LIFTS NORTHEAST ONCE IT IS WELL OUT TO SEA. MEANWHILE CLOSED 500 HPA LOW REMAINS OVER THE MARITIMES AND DRIFTS NORTH VERY SLOWLY THROUGH SUNDAY NIGHT. THE RESULT WILL BE A PROLONGED NORTHWEST FLOW BRINGING UNSEASONABLY COLD AIR FROM CENTRAL CANADA...ALONG WITH BRISK WINDS AND CLOUDS AND SNOW/RAIN FROM LAKE EFFECT. HIGH TEMPERATURES WILL BE ABOUT 10 DEGREES COOLER THAN NORMAL...WITH CLOUDS AND WIND MAKING IT FEEL EVEN COLDER. MODELS DISAGREE ON TRACK OF A LOW FORECAST TO DEVELOP IN THE SOUTHEASTERN STATES AND MOVE NORTHEAST. THE EUROPEAN MODEL WOULD BRING A SIGNIFICANT SNOWFALL WHILE THE GFS WOULD KEEP THE REGION NORTH AND WEST OF THE SNOW. AT THIS POINT WE WILL GO WITH CHANCE POPS. HIGH PRESSURE MOVES IN TUESDAY AND LOOKS LIKE IT WILL BE FOLLOWED BY ANOTHER CLIPPER TYPE SYSTEM WEDNESDAY. && .AVIATION /18Z WEDNESDAY THROUGH SUNDAY/... CLEARLY A MESS TODAY. GFL KICKS IT OFF WITH LIFR CIGS...WHILE ALB AND POU MVFR. THINGS WILL ONLY DETERIORATE AS LOW PRESSURE INCHES CLOSER. EXPANDING BATCH OF HEAVIER PRECIP OVER EASTERN PA ON RADAR LIKELY TO MAKE IT INTO REGION BY 00Z ACCORDING TO NAM. HAVE CONDITIONS DETERIORATING TO LIFR/IFR CIGS/VSBY IN MODERATE RAIN. WIND SHEAR WILL BE AN ISSUE...ESPECIALLY AT ALB AND POU...SO HAVE INCLUDED A GROUP FOR ALL PORTS 00-05Z. LOW PROGGED TO PASS RIGHT OVER ALB AREA. ONCE COLD FRONT PULLS THROUGH...WINDS MIX DOWN AND WIND SHEAR NOT AN ISSUE...BUT STRONG...GUSTY SURFACE WINDS WILL BE. THINGS LIGHTEN TO SHOWERY...AND WITH COLDER AIR PULLING IN...HAVE CALLED FOR -SHRASNPL AFT 10Z AT ALL. WITH SOME DEGREE OF WRAPAROUND EXPECTED BEHIND DEPARTING SYSTEM...HAVE INCLUDED VCSH ALL 15-18Z... BY WHICH TIME WE`RE AT VFR...THOUGH BKN-OVC. MOST CRITICAL ISSUE THEN WILL BE THE SURFACE WINDS. OUTLOOK... LATE THU NIGHT THRU FRI...VFR/MVFR WITH A CHANCE OF RAIN/SNOW SHOWERS EARLY PART. STRONG GUSTY WINDS LIKELY THROUGH PERIOD. SAT THRU SUN...VFR NO WX. && .FIRE WEATHER... LOW PRESSURE WILL TRACK NORTHEAST FROM THE LOWER MISSISSIPPI VALLEY INTO SOUTHEAST NEW YORK THROUGH TONIGHT...AND OFF THE NEW ENGLAND COAST THURSDAY. A WIDESPREAD MODERATE TO HEAVY RAINFALL IS EXPECTED ACROSS THE REGION TODAY AND TONIGHT...WITH SCATTERED RAIN AND SNOW SHOWERS ON THURSDAY. WINDS WILL BE FROM THE SOUTHEAST TO SOUTH AT 10-20 MPH TODAY...SHIFTING INTO THE W TO NW AND INCREASE TO 20-30 MPH TONIGHT AND THURSDAY. HAINES INDICES WILL ONLY REACH 2 TODAY...AND RANGE FROM 3 TO 4 FOR THU AFTERNOON...WITH HIGHEST VALUES ACROSS LOWER ELEVATIONS WITHIN THE MID HUDSON VALLEY. && .HYDROLOGY... A SIGNIFICANT PRECIPITATION EVENT IS EXPECTED TODAY INTO TONIGHT...WITH TOTAL PRECIPITATION GENERALLY AROUND 1.5 INCHES. TEMPERATURES WERE STILL BELOW FREEZING OVER THE ADIRONDACKS...THE LAKE GEORGE REGION...AND SOUTHERN VERMONT EARLY THIS MORNING...BUT THEY ARE EXPECTED TO WARM ABOVE FREEZING BY MID MORNING AND MOST OF THE PRECIP WILL COME AS RAIN THIS AFTERNOON AND TONIGHT AS THE MAIN STORM MOVES ACROSS THE REGION. RIVERS AND STREAMS ARE ALREADY RUNNING HIGH DUE TO THE ABUNDANCE OF ANTECEDENT RAINFALL...WHICH IS THE NORM FOR MID MARCH. FLOODING CONCERNS EXIST ACROSS MOST OF THE FORECAST AREA ALTHOUGH TEMPERATURES WILL PROBABLY REMAIN COOL ENOUGH IN THE ADIRONDACKS AND MOUNTAINS OF SOUTHERN VERMONT TO AVERT A RAPID MELTDOWN OF THE WINTER SNOW. THE MAIN AREAS OF CONCERN AT THIS POINT ARE FROM THE MOHAWK RIVER TO THE SOUTHEAST CATSKILLS AND FROM THE SOUTHWEST VERMONT AND THE HUDSON RIVER FROM SCHUYLERVILLE SOUTH AND EAST THROUGH THE BERKSHIRES AND LITCHFIELD HILLS. ESPECIALLY VULNERABLE WILL BE THE ESOPUS AND RONDOUT CREEKS AS WELL AS THE HOUSATONIC BASIN SOUTH OF MASSACHUSETTS. ALSO SNOWMELT MAY OCCUR IN THE CATSKILLS...SOUTHERN VERMONT AND THE BERKSHIRES WHICH WOULD ADD ADDITIONAL RUNOFF TO RIVERS IN THESE AREAS. THERE IS ALSO A POSSIBILITY OF SOME CONVECTION THIS AFTER NOON AND EVENING ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA WHICH COULD ADD TO THE PRECIP AMOUNTS. A FLOOD WATCH IS IN EFFECT FROM 2PM TODAY UNTIL 2PM THURSDAY. COLD AIR WILL BEGIN TO FLOW BACK INTO THE REGION TONIGHT AND CHANGE ANY LINGERING RAIN BACK TO SNOW. PLEASE REFER TO OUR ADVANCED HYDROLOGIC PREDICTION SERIES /AHPS/ PAGES ON THE WEB FOR DETAILS AND UPDATES ON THE RIVERS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR CTZ001-013. NY...FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR NYZ038>041-043- 047>054-058>061-063>066-082-084. WINTER STORM WARNING UNTIL 6 PM EDT THIS AFTERNOON FOR NYZ042. WINTER STORM WARNING UNTIL 6 AM EDT FRIDAY FOR NYZ032-033. MA...FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR MAZ001-025. VT...FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR VTZ013. WINTER STORM WARNING UNTIL 6 PM EDT THIS AFTERNOON FOR VTZ014- 015. && $$ SYNOPSIS...KL/TAW NEAR TERM...TAW SHORT TERM...KL LONG TERM...RCK AVIATION...ELH FIRE WEATHER...KL HYDROLOGY...RCK ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1144 AM MDT WED MAR 19 2008 .UPDATE...HAVE ISSUED A RED FLAG WARNING FOR THE WESTERN PORTIONS OF THE TRI STATE AREA AS RELATIVE HUMIDITIES HAVE DETERIORATED NEAR 15 PERCENT AND EXPECT THEM TO CONTINUE TO DROP BELOW 15 PERCENT THIS AFTERNOON. WINDS HAVE PICKED UP OUT OF THE SOUTHWEST THIS MORNING SUSTAINED BETWEEN 15 AND 20 MPH WITH GUSTS OVER 25 MPH CREATING CRITICAL FIRE WEATHER CONDITIONS. EXPECT WINDS TO DECREASE AND RH TO RECOVER LATER THIS AFTERNOON. TEMPERATURES ARE ON TRACK SO FAR TODAY AND EXPECT MAX TEMPS ACROSS THE TRI STATE AREA TO REACH INTO THE MID TO UPPER 60`S TODAY. BURTIS .DISCUSSION... 222 AM MDT WED MAR 19 2008 FORECAST PROBLEMS WILL BE HIGH TEMPERATURES/WINDS/FIRE WEATHER CONCERNS TODAY...TEDIOUS TEMPERATURE/WIND FORECAST THURSDAY...AND HOW MUCH TO COOL DOWN FRIDAY...AND CHANCES OF PRECIPITATION THURSDAY NIGHT AND AT THE BEGINNING OF THE WEEKEND. SATELLITE SHOWING A PROGRESSIVE FLOW FROM THE CENTRAL PACIFIC THROUGH THE CONTINENTAL UNITED STATES. SOUTHERN PLAINS LOW LOOKING LIKE IT IS BEGINNING TO PUSH EAST. FLOW SLOWS UP AND IS BLOCKY IN THE CENTRAL ATLANTIC. AT JET LEVEL...INITIALLY MODELS DID WELL WITH JET POSITION AND STRENGTH...ESPECIALLY WITH THE JET TO OUR NORTH. THE NAM AND UKMET WERE SLIGHTLY BETTER THAN THE GFS. AT 06Z...THE MODELS WERE A LITTLE TOO FAR SOUTH WITH THE JET POSITION. AT MID LEVELS...MODELS ARE REASONABLY INTIALIZED AND SIMILAR. ALL OF THEM ARE CATCHING NORTHERN STREAM SHORTWAVE TROUGH WELL. THEY DO DIFFER ON THE SOUTHERN PLAINS LOW BUT DIFFERENCES DO NOT APPEAR SIGNIFICANT AT THIS TIME. THE GFS DOES LOOK TO HAVE TO BE TOO MOIST. AT LOW LEVELS...THE NAM AND RUC WERE DOING THE BEST WITH THE WIND FIELD. MODELS WERE HAVING DIFFICULTY WITH THE COLD POOL TO OUR EAST AND TO A LESSER EXTENT TO OUR NORTH. MODELD DID NOT HAVE THE EASTERN COLD POOL FAR ENOUGH SOUTH AND EAST. OVERALL THE GFS WAS DOING SLIGHTLY BETTER THAN THE UKMET AND ECMWF. WILL BE GOING WITH A BLEND OF THE MODELS WITH A TREND TOWARD THE WARMER...DRIER...AND WINDIER OUTPUT. TODAY/TONIGHT...THE MAIN JET WILL REMAIN TO THE NORTH OF THE AREA THROUGH THE DAY WITH FORECAST AREA UNDER JET SUBSIDENCE. AREA LOOKS TO HAVE PLENTY OF SUN. MAY HAVE AFTERNOON CUMULUS BUILD UP AGAIN BUT IT LOOKS A LITTLE LESS THAN YESTERDAY. SNOW FIELD WAS A NON ISSUE YESTERDAY WITH THE TEMPERATURES WITH GUIDANCE AND FORECAST BEING TOO COOL. THIS HAS BEEN THE TREND OF THE MAV/GFS LATELY. USING THE TEMPERATURE CHANGE FROM YESTERDAY...DIURNAL RANGE...AND BIASES FROM THE 2 METER AND 850 MB...YIELDED TEMPERATURES IN THE LOWER AND MIDDLE 60S WHICH IS WARMER THAN THE PREVIOUS FORECAST. BASED ON TRAJECTORY OF THE SYSTEM TO OUR NORTH...DRY LOW LEVEL AIR MASS...AND SUBSIDENCE...EXPECT THE WINDS OVER MOST OF THE AREA TO BE BREEZY AGAIN. ANOTHER PROBLEM WITH THIS IS LOW DEWPOINTS EXPECTED. DEWPOINTS NEAR WESTERN END OF OUR FORECAST AREA AND UPSTREAM RANGE FROM THE MIDDLE TEENS TO NEAR 20 AND THIS IS IN THE MIDDLE OF THE NIGHT. AREA SOUNDINGS WOULD SHOW THAT DEWPOINTS WILL HAVE POTENTIAL TO TANK ONCE MIXING OCCURS. MOST MODEL OUTPUT IS WAY TOO HIGH ON MOISTURE. USED THE NGM AS A FIRST GUESS SINCE IT WAS THE LOWEST...AND THEN MODIFIED. WIND WIND WILL BE THE WILD CARD AND WILL BE CLOSE. MAY NEED TO ISSUE A WARNING. WIND FIELD IS VERY LIGHT TONIGHT...ESPECIALLY IN THE EASTERN HALF. THERE IS A TENDENCY TOWARD UPSLOPE BUT SINCE SPEEDS ARE NOT THAT HIGH...DO NOT BUY THE HIGHER DEWPOINTS. WITH LITTLE CLOUD COVER... BELIEVE THAT LOWS COULD DROP WELL BELOW GUIDANCE. TRENDED MINS... ESPECIALLY IN THE EAST...TO THAT DIRECTION. THURSDAY/THURSDAY NIGHT...MODELS ARE IN CLOSER AGREEMENT TO THE JET POSITION THAN THEY WERE YESTERDAY. ALTHOUGH THERE IS SLIGHT DIFFERENCE BY THE END OF THE DAY. THE UKMET AND NAM ARE FURTHER NORTH WITH THE AXIS. THE NAM BRINGS IN A BETTER RIGHT REAR QUADRANT IN THE AFTERNOON THAN THE UKMET WHICH KEEPS US IN MUCH LESS LIFT. THE GFS AGAIN IS SLIGHTLY FURTHER SOUTH. HOWEVER...IT DOES NOT BRING THE AXIS OVER THE AREA UNTIL THE AFTERNOON. ALL THE MODELS BRING THE RIGHT REAR QUADRANT ACROSS THE FORECAST IN THE 00Z TO 06Z TIME FRAME. MAIN SYSTEM AND STRONGEST LIFT REMAIN WELL NORTH OVER THE NORTH CENTRAL PORTION OF THE COUNTRY. HOWEVER...THE MODELS DO SWING A DECENT SHORTWAVE TROUGH THROUGH THE AREA DURING THE EVENING. THEN SUBSIDENCE AND AN EXTREMELY DRY AIR MASS ALOFT QUICKLY MOVE IN AFTER 06Z. SO WHATEVER PRECIPITATION FALLS WILL BE DONE BY 06Z. POINT SOUNDINGS WOULD INDICATE THAT LOW LEVELS WILL BE DRY. CONSIDERING THAT THE FRONT AND WESTERLY SURFACE WINDS WILL PRECEDE UPPER LIFT...WOULD AGREE WITH THAT ASSESSMENT. SINCE SYSTEM WILL GO QUICKLY THROUGH...DO NOT BELIEVE THERE WILL BE TIME FOR THE MOISTURE TO SATURATE DOWN. THE TENDENCY WITH THESE FAST WEST TO NORTHWEST SHORTWAVES HAS BEEN TO OVERPRODUCE PRECIPITATION. AM LEANING TOWARD JUST HAVING EVENING SPRINKLES AT THIS TIME. HIGH TEMPERATURE FORECAST WILL BE TRICKY. A LOT WILL DEPEND ON HOW FAST WEAK BOUNDARY/EASTERLY WINDS MIX OUT AND PUSH TO THE EAST. GIVEN THE FLOW ALOFT AND GOOD MIXING EXPECTED...THINK THAT THE BOUNDARY WILL MOVE EAST RAPIDLY. HOWEVER...CLOUDS INCREASE AND FRONT APPROACHES IN THE AFTERNOON. USING DIFFERENT TEMPERATURE METHODS POINTED TO TEMPERATURES BEING NEAR TO SLIGHTLY ABOVE 70 OVER MOST OF THE AREA. IF HAVE LESS CLOUDS AND SLOWER FRONT...WILL BE MUCH WARMER. MODELS...ESPECIALLY THE NAM...ALSO BRING UP THE WINDS TO NEAR OR SLIGHTLY ABOVE 20 KNOTS. NOT THE RIGHT TIME OF DAY YOU WOULD EXPECT TO GET STRONG WINDS. MODELS ARE INDICATING STRONG SUBSIDENCE AND MAY BE POSSIBLE AND CONSIDERING A FAVORABLE TRACK OF THE UPPER SYSTEM TO BRING IN STRONGER WINDS...THIS DOES SEEM REASONABLE. WILL INCREASE WINDS FOR THE NIGHT WHICH WILL KEEP MINS MILD. FRIDAY/FRIDAY NIGHT...MAIN JET IS FURTHER SOUTH. HOWEVER...NAM AND GFS DEVELOP A SECONDARY AXIS THAT PUTS THE AREA...MOSTLY THE NORTHEAST HALF...IN SOME LIFT DURING THE AFTERNOON. HOWEVER THERE LOOKS TO BE PLENTY OF SUN...SPRING SUN...WITH DOWNSLOPE COMPONENT TO THE WINDS. MODELS HAVE BEEN TOO COOL IN THIS SETUP THIS MONTH AND WILL TEND TO GO TOWARD THE WARMER GUIDANCE. WILL ALSO PROBABLY KEEP THE WINDS UP CONSIDERING THAT MIXING AND SUBSIDENCE WILL CONTINUE. AREA STAYS UNDER THE ENTRANCE REGION OF THE JET THROUGH THE NIGHT AND A STRONG SHORTWAVE IS APPROACHING FROM THE NORTHWEST. POINT SOUNDINGS SHOW THAT THE LOW LEVELS ARE TOO DRY TO ALLOW MEASURABLE PRECIPITATION DURING THE NIGHT. WILL KEEP IT DRY BUT RAISE THE SILENT POPS. SATURDAY...MOISTURE AND FORCING COME TOGETHER DURING THE DAY. THE LAPSE RATES ARE THE BEST IN THE SOUTHWEST HALF. FORECAST HAS PRECIPITATION IN THERE AND WILL ONLY TWEEK IF NECESSARY. COOLER TEMPERATURES FOR SATURDAY LOOK FINE AT THIS TIME. THANKS TO ALL FOR COLLABORATION...IT WAS MUCH APPRECIATED. BULLER && .AVIATION... 1144 AM MDT WED MAR 19 2008 FOR 18Z TAFS... VFR CONDITIONS EXPECTED THROUGH THE ENTIRE TAF PERIOD. WINDS HAVE INCREASED OUT OF THE SOUTHWEST FROM 15 TO 20 KTS WITH HIGHER GUSTS IN KGLD. KMCK SHOULD FOLLOW SHORTLY WITH WINDS TO PICK UP. WILL SEE THESE WINDS DROP TOWARD THE EVENING HOURS AS THEY ARE DIURNALLY DRIVEN. BURTIS && .GLD WATCHES/WARNINGS/ADVISORIES... KS...RED FLAG WARNING UNTIL 5 PM MDT /6 PM CDT/ THIS AFTERNOON FOR KSZ001-013-027-041-042. NE...NONE. CO...RED FLAG WARNING UNTIL 5 PM MDT THIS AFTERNOON FOR COZ252>254. && $$ WFO GOODLAND ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 418 PM EDT WED MAR 19 2008 .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOW AN UPR LVL TROF AND SHORTWAVE APPROACHING NRN LAKE SUPERIOR. MODELS INDICATE THAT THIS SHORTWAVE WILL BRUSH ACROSS THE UPR GREAT LAKES BEFORE EXITING EAST BY 12Z THU. COLD ADVECTION BEHIND THIS SHORTWAVE SHOULD LEAD TO SOME LES FORMATION TONIGHT AS 850 MB TEMPS OF -14 TO -15C MOVE ACROSS THE LAKE. SHORT TERM (TONIGHT AND THURSDAY)... TONIGHT...AS SHORTWAVE OVER ONTARIO CROSSES THE LAKE TONIGHT INCREASINGLY COLDER AIR WILL BE ADVECTED INTO THE REGION. 850MB TEMPS ARE PROGGED TO DROP TO -14 TO -15C BY 06Z TONIGHT AND WITH NNW WIND FLOW...WOULD EXPECT LAKE EFFECT SNOW SHOWERS TO FORM AND IMPACT MUCH OF THE NORTHERN AND EASTERN U.P. HOWEVER...DEPTH OF COLD LAYER WILL STRUGGLE TO REACH 5KFT SO THIS WILL LIMIT STRENGTH OF LES BANDS DESPITE FAVORABLE DENDRITIC GROWTH REGION PROGGED WITHIN THE CLOUD LAYER. THIS FAVORABLE SNOW GROWTH WILL RESULT IN SNOW/WATER RATIOS CLOSER TO 30 TO 1. LOCAL WRF-ARW MODEL SIMILAR TO PREVIOUS RUN WHICH DEPICTS MORE DOMINANT BANDS SETTING UP OVER WRN ALGER/ERN MQT COUNTY AND OVER LUCE COUNTY. IF BANDS STAY OVER A LOCATION FOR ANY LENGTH OF TIME...THERE COULD BE LOCAL ACCUMULATIONS OF UP TO 2 INCHES. MOST LOCATIONS OVER NCNTRL AND ERN ZONES SHOULD SEE AN INCH OR LESS. FOLLOWED PRETTY CLOSE TO GFS MOS GUIDANCE FOR MIN TEMPS WITH LOWS REACHING INTO THE MID TEENS OVER THE WRN INTERIOR AND UPR TEENS TO AROUND 20F EAST. THURSDAY...LES BANDS WILL CONTINUE IN THE MORNING OVER THE ERN COUNTIES ALTHOUGH THE HEART OF THE COLDEST 850 MB TEMPS WILL HAVE MOVED EAST AFT 12Z. INCREASINGLY DIFFLUENT FLOW AHEAD OF MID-UPR LVL RIDGE WILL ALLOW FOR SUBSIDENCE INVERSION TO LOWER BLO 3KFT BY MORNING. THIS ALONG WITH DAYTIME HEATING WILL LIKELY DISRUPT ANY REMAINING LES BANDS OVER ERN COUNTIES BY AFTERNOON. MODELS STILL SHOW 850MB TEMPS -9 TO -12C WITH SNDGS INDICATING POTENTIAL FOR SOME DIURNAL CU TO FORM OVER INLAND AREAS. AGAIN FOLLOWED GFS MOS GUIDANCE FOR TEMPS WITH WARMEST READINGS EXPECTED IN THE SOUTH CENTRAL U.P. FOR DOWNSLOPE AREAS ALONG LAKE MI. .LONG TERM (THURSDAY NIGHT THROUGH NEXT WEDNESDAY)... TO BEGIN THE PERIOD...TROUGH OVR NEW ENGLAND AND EASTERN CANADA KEEPS NW FLOW ALOFT INTO GREAT LAKES WHILE A SFC HIGH PRESSURE RIDGE DRIFTS ACROSS ONTARIO AND UPR GREAT LAKES. SHORTWAVE AND SFC LOW DIVING ESE ACROSS PLAINS STILL PROJECTED TO MISS UPR MI WITH ANY SNOW ON FRIDAY. STRIPE OF ACCUMULATING SNOW LIKELY FM NORTHERN SD ACROSS SOUTHERN MN AND INTO SOUTHWEST WI. ATTM LOOKS LIKE NORTH EDGE OF SNOW WILL STAY OUT OF CWA BUT THERE COULD BE SOME INCREASING CLOUDS ALONG THE WI BORDER ON FRI. NORTH TO NORTHEAST WINDS ON SOUTHERN FLANK OF THE HIGH AND SHALLOW COLD AIR LEFT OVER FM BRIEF COLD PUSH ON THU COULD YIELD LK EFFECT SNOW SHOWERS AND FLURRIES INTO FRIDAY. BY FRI AFTN PREFER THE DRIER LOOK OF NAM SOUNDINGS AS HIGHER SUN ANGLE/DAYTIME HEATING SHOULD RESULT IN NOTHING MORE THAN A FEW LK EFFECT FLURRIES. WEAK SHORTWAVE RIDGING EXPECTED TO START THE WEEKEND. NE WINDS AND COOL AIR CONTINUE TO AFFECT NORTHERN UPR MI. CANNOT REALLY RULE OUT SOME LK EFFECT FLURRIES...BUT SINCE OVERALL EXPECT DOWNWARD MOTION AND INVERSIONS LOWER THAN H9...DECIDED TO LEAVE IT OUT FOR NOW. GFS/ECMWF CONTINUE TO SHOW SHORTWAVE TROUGH AND A WEAK SFC TROUGH PRESSING INTO UPR LAKES SATURDAY NIGHT INTO SUNDAY. SOME WEAK LIFT WITH THE FEATURES AND AN INCREASE IN MID LEVEL MOISTURE MAY ALLOW FOR SOME LIGHT SNOW TO PUSH INTO WESTERN HALF OF CWA. LIGHT NORTH WINDS WITH H85 TEMPS AS LOW AS -14C COMBINED WITH THE LARGE SCALE LIFT SHOULD LEAD TO INCREASE IN LK EFFECT OVR NW AND NCNTRL CWA. COLDER 00Z ECMWF RESULTS IN A PUSH OF VERY CHILLY AIR FOR LATE MARCH SUN NIGHT INTO MONDAY. 1000-500MB THICKNESSES GET CLOSE TO 500DAM AND H85 TEMPS ARE AROUND -18C AT 12Z MON. WITH NE WINDS...LK EFFECT SNOW SHOWERS LOOK LIKELY FOR NW AND NORTH CENTRAL CWA. LATEST ECMWF NOT NEAR AS AGGRESSIVE IN KEEPING THE COLD AIR AROUND. IN FACT ...ECMWF NOW LOOKS A LOT LIKE EARLIER RUNS OF GFS WHICH BROUGHT LOW PRESSURE AND A SHOT FOR SNOW ACROSS UPR GREAT LAKES ON TUE. CANADIAN STILL DRY AND EARLIER ENSEMBLES KEPT THE SYSTEM SUPPRESSED TO THE SOUTH WHILE A VIGOROUS STORM TAKES AIM ON THE MID ATLANTIC WITH LATE SEASON SNOWSTORM. SINCE THERE ARE STILL CONFLICTING SIGNALS...STUCK WITH A DRY FORECAST FOR TUE/WED. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... DIURNAL CU HAS RESULTED IN AN OCCASIONAL BKN MVFR CEILING AT KCMX THIS AFTERNOON. ADVECTION OF COLDER AIR FROM NORTH OF LAKE SUPERIOR WILL INCREASE LAKE CLOUDS AS A PREVAILING MVFR DECK MOVES IN AT BOTH KCMX AND KSAW LATER THIS EVENING. LAKE EFFECT SNOW IS ALSO POSSIBLE AT BOTH SITES BY LATE EVENING CONITNUING INTO THE OVERNIGHT HOURS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT WINDS TO 30 KNOTS TONIGHT INTO THU MORNING OVER THE ERN HALF OF LAKE SUPERIOR FROM TIGHT PRESSURE GRADIENT BETWEEN LOW PRESSURE TO THE EAST AND A HIGH BUILDING IN FROM SOUTH CENTRAL CANADA. WITH COLD AIR TONIGHT AND STRONGER WINDS OVER THE EASTERN CWA...HEAVY FREEZING SPRAY WILL BRIEFLY BE POSSIBLE ACROSS THE CENTRAL AND EASTERN PARTS OF THE LAKE. OTHERWISE...WINDS THROUGH THE REST OF THE FCST PD SHOULD BE 25 KNOTS OR LESS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 2 AM TO 8 AM EDT THURSDAY FOR LSZ264-266-267. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM...VOSS LONG TERM...JLA AVIATION/MARINE...VOSS mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 417 PM EDT WED MAR 19 2008 UPDATED FOR AVIATION DISCUSSION .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOW AN UPR LVL TROF AND SHORTWAVE APPROACHING NRN LAKE SUPERIOR. MODELS INDICATE THAT THIS SHORTWAVE WILL BRUSH ACROSS THE UPR GREAT LAKES BEFORE EXITING EAST BY 12Z THU. COLD ADVECTION BEHIND THIS SHORTWAVE SHOULD LEAD TO SOME LES FORMATION TONIGHT AS 850 MB TEMPS OF -14 TO -15C MOVE ACROSS THE LAKE. SHORT TERM... TONIGHT...AS SHORTWAVE OVER ONTARIO CROSSES THE LAKE TONIGHT INCREASINGLY COLDER AIR WILL BE ADVECTED INTO THE REGION. 850MB TEMPS ARE PROGGED TO DROP TO -14 TO -15C BY 06Z TONIGHT AND WITH NNW WIND FLOW...WOULD EXPECT LAKE EFFECT SNOW SHOWERS TO FORM AND IMPACT MUCH OF THE NORTHERN AND EASTERN U.P. HOWEVER...DEPTH OF COLD LAYER WILL STRUGGLE TO REACH 5KFT SO THIS WILL LIMIT STRENGTH OF LES BANDS DESPITE FAVORABLE DENDRITIC GROWTH REGION PROGGED WITHIN THE CLOUD LAYER. THIS FAVORABLE SNOW GROWTH WILL RESULT IN SNOW/WATER RATIOS CLOSER TO 30 TO 1. LOCAL WRF-ARW MODEL SIMILAR TO PREVIOUS RUN WHICH DEPICTS MORE DOMINANT BANDS SETTING UP OVER WRN ALGER/ERN MQT COUNTY AND OVER LUCE COUNTY. IF BANDS STAY OVER A LOCATION FOR ANY LENGTH OF TIME...THERE COULD BE LOCAL ACCUMULATIONS OF UP TO 2 INCHES. MOST LOCATIONS OVER NCNTRL AND ERN ZONES SHOULD SEE AN INCH OR LESS. FOLLOWED PRETTY CLOSE TO GFS MOS GUIDANCE FOR MIN TEMPS WITH LOWS REACHING INTO THE MID TEENS OVER THE WRN INTERIOR AND UPR TEENS TO AROUND 20F EAST. THURSDAY...LES BANDS WILL CONTINUE IN THE MORNING OVER THE ERN COUNTIES ALTHOUGH THE HEART OF THE COLDEST 850 MB TEMPS WILL HAVE MOVED EAST AFT 12Z. INCREASINGLY DIFFLUENT FLOW AHEAD OF MID-UPR LVL RIDGE WILL ALLOW FOR SUBSIDENCE INVERSION TO LOWER BLO 3KFT BY MORNING. THIS ALONG WITH DAYTIME HEATING WILL LIKELY DISRUPT ANY REMAINING LES BANDS OVER ERN COUNTIES BY AFTERNOON. MODELS STILL SHOW 850MB TEMPS -9 TO -12C WITH SNDGS INDICATING POTENTIAL FOR SOME DIURNAL CU TO FORM OVER INLAND AREAS. AGAIN FOLLOWED GFS MOS GUIDANCE FOR TEMPS WITH WARMEST READINGS EXPECTED IN THE SOUTH CENTRAL U.P. FOR DOWNSLOPE AREAS ALONG LAKE MI. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... DIURNAL CU HAS RESULTED IN AN OCCASIONAL BKN MVFR CEILING AT KCMX THIS AFTERNOON. ADVECTION OF COLDER AIR FROM NORTH OF LAKE SUPERIOR WILL INCREASE LAKE CLOUDS AS A PREVAILING MVFR DECK MOVES IN AT BOTH KCMX AND KSAW LATER THIS EVENING. LAKE EFFECT SNOW IS ALSO POSSIBLE AT BOTH SITES BY LATE EVENING CONITNUING INTO THE OVERNIGHT HOURS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT WINDS TO 30 KNOTS TONIGHT INTO THU MORNING OVER THE ERN HALF OF LAKE SUPERIOR FROM TIGHT PRESSURE GRADIENT BETWEEN LOW PRESSURE TO THE EAST AND A HIGH BUILDING IN FROM SOUTH CENTRAL CANADA. WITH COLD AIR TONIGHT AND STRONGER WINDS OVER THE EASTERN CWA...HEAVY FREEZING SPRAY WILL BRIEFLY BE POSSIBLE ACROSS THE CENTRAL AND EASTERN PARTS OF THE LAKE. OTHERWISE...WINDS THROUGH THE REST OF THE FCST PD SHOULD BE 25 KNOTS OR LESS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 2 AM TO 8 AM EDT THURSDAY FOR LSZ264-266-267. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM...VOSS AVIATION/MARINE...VOSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 351 PM CDT WED MAR 19 2008 .DISCUSSION... FORECAST CONCERN NEAR TERM...HANDLING SHORT WAVE MOVING ACROSS EASTERN SODAK. THIS SYSTEM SHOULD DROP SOUTHEAST AND AFFECT PARTS OF WC/SW MN DURING THE NIGHT. APPEARS QUITE STRONG ON WATER VAPOR IMAGERY(DARKENING NOTED ON WESTERN SIDE). MAY SEE SOME SLUSHY ACCUMULATIONS FAR SOUTHWEST OVERNIGHT...BUT SHOULD REMAIN OVER THAT REGION. CLOUDS TO SPREAD OVER MN PORTION WITH HIGH CLOUDS INTO WI. TEMPERATURES SHOULD BE HELD UP SOME WITH THE THICKER CLOUD COVER...AND OPTED TO GO A BIT WARMER ON LOWS TONIGHT...MAINLY SOUTHWEST. THEN FOCUS TURNS TO DEVELOPING SNOW EVENT FOR THU NIGHT AND FRIDAY ACROSS MAINLY SOUTHERN CWA. 12Z NAM APPEARED TO BE ODD MODEL OUT THIS RUN...WITH SNOW BAND DEVELOPING ACROSS CENTRAL MN DURING THIS PERIOD. IT ACTUALLY CUT OFF MID LEVEL CIRCULATION ACROSS THIS REGION WITH RATHER ROBUST DEFORMATION SETTING UP. OPTED TO GO WITH MORE CONSISTENT GFS...WHICH CONTINUES TO TREND SNOW BAND ACROSS SOUTHERN CWA...MAINLY ALONG MN RIVER VALLEY REGION. SURFACE LOW PROGGED TO DEVELOP OVER NEB AREA AND MOVE EAST ACROSS EXTREME SOUTHERN IOWA FRIDAY. MAIN H5 WAVE TO GRADUALLY DEEPEN WITH TIME AS MAIN ENERGY ARRIVE FROM THE WESTERN US. FOLLOWED DEVELOPMENT OF H7 WAVE...AND CIRCULATION DOES CUT OFF WITH TIME-FRIDAY. THIS SHOULD PROVIDE FOR GOOD DEFORMATION AXIS ACROSS MN RIVER VALLEY REGION...PERHAPS AFFECTING SOUTHERN METRO AS WELL. WENT WITH WINTER STORM WATCH WITH MARGINAL STORM ACCUMULATIONS/AROUND 6 INCHES TOTAL/ IN THIS AREA. GOOD BE MORE IF WE CAN GET SUSTAINED LIFT OVER A REGION FOR FRIDAY. WILL BE HEAVY/WET SNOW NONETHELESS. SYSTEM SHOULD MOVE OUT FRIDAY EVENING...LEAVING SOME CLOUD COVER AND THREAT OF LIGHT SNOW/FLURRIES INTO SUNDAY MORNING. OTHERWISE...UPPER FLOW BECOMING MORE ZONAL WITH TIME...AND COULD BE SUSCEPTIBLE TO FAST MOVING STORM SYSTEMS. BEST CHANCE OF THIS OCCURRING APPEARS TO BE MONDAY NIGHT AND TUESDAY OVER THE REGION...AND WENT WITH SOME SMALL CHANCE POPS ACROSS THE REGION THEN. TEMPERATURES TO REMAIN AT OR SLIGHTLY BELOW NORMAL DURING THE EXTENDED PERIOD. && .AVIATION.../18Z TAF ISSUANCE/ SHORT WAVE DROPPING SE THROUGH SD AT THIS TIME APPEARS A BIT STRONGER THAN THE 12Z NAM OR GFS. RUC SEEMS TO HAVE THE BEST HANDLE ON IT...BUT WEAKENS IT THIS EVENING...AS DO THE OTHER MODELS...WITH RIDGE MOVING SLOWLY EASTWARD ACROSS MN. ABUNDANT MID AND HIGH CLOUDINESS. SATURATION DOES NOT APPEAR TO BE TOO PROMISING. WL KEEP CHC FLURRIES LATE TONIGHT IN SW MN. MAY NEED TO ADD AXN TO THIS. OTHERWISE LIGHT NW WINDS WILL GRADUALLY SHIFT TO THE NORTHEAST OVER MOST AREAS... EXCEPT RWF WHERE SFC LOW WL SLIDE BY TO THE SOUTHWEST. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WATCH FROM THURSDAY EVENING THROUGH FRIDAY EVENING FOR BLUE EARTH-BROWN-CARVER-CHIPPEWA-DAKOTA-FARIBAULT- FREEBORN-GOODHUE-KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN- MCLEOD-MEEKER-NICOLLET-POPE-REDWOOD-RENVILLE-RICE-SCOTT- SIBLEY-STEELE-STEVENS-SWIFT-WASECA-WATONWAN-YELLOW MEDICINE. WI...NONE. && $$ TDK/DWE mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1257 PM CDT WED MAR 19 2008 .DISCUSSION... SUBSIDENCE AND WEAK HIGH PRESSURE PROVIDING MOSTLY CLEAR SKIES THIS MORNING...BUT COMBO OF APPROACHING WAVE AND SOME POSSIBILITY OF CU SHOULD GIVE A MIX OF CLOUDS AND SUN FOR AFTERNOON. MODELS WEAKEN THE LOW PRESSURE SLIDING THROUGH THE DAKOTAS INTO IA LATER TODAY AND TONIGHT. JUST THE SOUTHWEST AND FAR SOUTH CENTRAL AND SOUTHWEST SEE DECENT SATURATION IN THE COLUMN AS THIS WAVE PASSES BY. HAVE DELAYED THE CHANCE OF PRECIP...BUT KEEP THE SAME GENERAL AREA. WILL ALSO BE MILD ENOUGH TO SEE A RAIN AND SNOW MIX AS TEMPS COOL FROM A HIGH IN THE 40S. STRONGER SYSTEM TO MOVE THROUGH THE AREA THURSDAY AFTERNOON THROUGH FRIDAY WITH MUCH BETTER PRECIPITABLE WATER TO WORK WITH. LIKE THE TRENDS OF THE ECMWF/GFS/SREF AS NAM HAS BEEN JUMPING AROUND THE LAST FEW RUNS. ECMWF AND SREF TAKE A 700 MB LOW GENERALLY ESE ACROSS SOUTHERN MN WHICH WOULD BE A GOOD TREND FOR SNOW. WARMER 1000-850 THICKNESS SUPPORTS A RAIN AND SNOW MIX FAR SOUTH OR SOUTHWEST. FRONTOGENETIC BAND COULD SET UP ACROSS SOUTHERN MN. GENERALLY AGREE WITH HPC OF POSSIBLE 4 TO 6 INCH SNOWS ACROSS THIS AREA. CHANCE FOR LIGHT SNOW WILL LINGER INTO THE WEEKEND WITH A COUPLE OF TROFS IN THE NW FLOW. ENSEMBLE TEMPS FOR THE END OF THE WEEKEND INTO EARLY NEXT WEEK SHOWING INCREASING UNCERTAINTY...AND POSSIBLE TREND FOR A COUPLE OF COLDER DAYS. HAVE DROPPED MAX TEMPS A JUST A BIT FOR SUNDAY. WILL BE INTERESTING TO SEE WHAT DEVELOPS. && .AVIATION.../18Z TAF ISSUANCE/ SHORT WAVE DROPPING SE THROUGH SD AT THIS TIME APPEARS A BIT STRONGER THAN THE 12Z NAM OR GFS. RUC SEEMS TO HAVE THE BEST HANDLE ON IT...BUT WEAKENS IT THIS EVENING...AS DO THE OTHER MODELS...WITH RIDGE MOVING SLOWLY EASTWARD ACROSS MN. ABUNDANT MID AND HIGH CLOUDINESS. SATURATION DOES NOT APPEAR TO BE TOO PROMISING. WL KEEP CHC FLURRIES LATE TONIGHT IN SW MN. MAY NEED TO ADD AXN TO THIS. OTHERWISE LIGHT NW WINDS WILL GRADUALLY SHIFT TO THE NORTHEAST OVER MOST AREAS... EXCEPT RWF WHERE SFC LOW WL SLIDE BY TO THE SOUTHWEST. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JPR/TDK mn