AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 1010 AM EST SAT FEB 10 2007 .UPDATE...LOWERED DEWPOINTS/RHS ACROSS THE PENINSULA AFTER LOOKING A THE RUC, WRF, AND CURRENT TRENDS. THE RESULT IS RED FLAG CONDITIONS WILL BE POSSIBLE ACROSS JUST ABOUT ALL OF SOUTH FLORIDA EXCEPT FAR WESTERN COLLIER COUNTY AND ALONG THE IMMEDIATE EAST COAST THIS AFTERNOON. WAVE HEIGHTS WERE ALSO TWEAKED DOWN DURING SUNDAY SINCE THE HEIGHTS SEEMED TO JUMP UP TOO QUICKLY FROM THE NORTHERLY WINDS. OTHERWISE, THE REST OF THE FORECAST PACKAGE SEEMS TO BE ON TRACK AND NO MAJOR CHANGES WERE MADE. .PREVIOUS DISCUSSION... MOSTLY CLOUDY SKIES ARE IN PLACE ACROSS SOUTH FLORIDA THIS MORNING...AS MID AND HIGH LEVEL MOISTURE CONTINUES TO BE ADVECTED ACROSS THE REGION IN SUBTROPICAL BRANCH OF THE UPPER LEVEL JET. EXPECT THIS TREND TO CONTINUE FOR REMAINDER OF THE WEEKEND...WITH PARTLY TO MOSTLY SKIES THROUGH SUNDAY. IN THE LOWER LEVELS...DRY NORTHWEST FLOW THROUGHOUT THE BOUNDARY LAYER ON SATURDAY WILL BOTH INHIBIT DEVELOPMENT OF EAST COAST SEABREEZE AND ENHANCE THE FIRE WEATHER THREAT FOR INTERIOR AND EAST COAST LOCATION...AND WILL HIGHLIGHT THIS THREAT IN UPCOMING ISSUANCE OF THE FWFMFL. MODELS CONTINUE TO SHOW GOOD AGREEMENT IN FORECASTING AN EASTWARD TRANSLATION OF A WEAK MID-LEVEL VORT MAX...CURRENTLY LOCATED OVER NORTHERN MEXICO...DURING THE DAY ON SUNDAY. THIS WILL ULTIMATELY ALLOW LOW-LEVEL FLOW TO GRADUALLY VEER FROM NORTHWEST TO EAST ON SUNDAY...SETTING THE STAGE FOR AN INCREASING THREAT OF RIP CURRENTS ALONG THE ATLANTIC COAST. LOW-LEVEL WINDS WILL CONTINUE TO VEER TO THE SOUTHEAST ON SUNDAY NIGHT/MONDAY...WITH DEVELOPING WARM ADVECTION REGIME LEADING TO RAPIDLY INCREASING RAINFALL CHANCES DURING THIS PERIOD. MODELS INDICATE THAT RICH TROPICAL MOISTURE WILL SPREAD INLAND DURING THE DAY ON MONDAY...WITH SURFACE DEW POINTS INCREASING TO 65-70 F AND 850 MB DEW POINTS CLIMBING TO 12-15 C. LARGE SCALE ASCENT WILL INCREASE DURING THE DAY WITH APPROACH OF MID-LEVEL SHORTWAVE FORM THE WEST AND INCREASING WARM ADVECTION...AND EXPECT A GOOD COVERAGE OF RAIN AND SHOWERS FOR THE ENTIRE AREA FROM MONDAY INTO TUESDAY MORNING. WILL ALSO CONTINUE TO MENTION ISOLATED THUNDERSTORMS...GIVEN PRESENCE OF 30-40 KNOT FLOW IN THE MID-LEVELS AND MAGNITUDE OF INSTABILITY BOTH AT THE SURFACE AND ALOFT. GIVEN LACK OF A STRONG UPPER LEVEL SHORTWAVE...EXPECT THE COVERAGE OF THUNDERSTORMS TO REMAIN ISOLATED AT BEST. HOWEVER...GIVEN VERY GOOD CONSISTENCY AMONG THE GFS/UKMET/CMC GUIDANCE...HAVE INCREASED POPS INTO THE LIKELY CATEGORY FOR MUCH OF THE REGION ON MONDAY AND MONDAY NIGHT. PRECIPITATION CHANCES WILL CONTINUE THROUGHOUT THE DAY ON TUESDAY AND INTO AT LEAST THE FIRST HALF OF WEDNESDAY...BUT WILL GRADUALLY DIMINISH AS LOW-LEVEL WINDS VEER TO SOUTHWEST IN RESPONSE TO THE PASSAGE OF A PRE-FRONTAL TROUGH ASSOCIATED WITH DEVELOPING SURFACE CYCLONE OVER THE SOUTHEASTERN STATES. TIMING OF THE TRUE COLD FRONTAL PASSAGE IS STILL UNCERTAIN AT THIS POINT...WITH AVAILABLE GUIDANCE FROM THE GFS/ECMWF/CMC ALL INDICATING A DIFFERENT TIMING DURING THE DAY ON WEDNESDAY. AT THIS POINT...WILL SPLIT THE DIFFERENCE AND INDICATE FRONT ENTERING THE NORTHWEST COUNTIES ON WEDNESDAY MORNING...AND MOVING OFF THE SOUTHEAST COAST BY LATE AFTERNOON. NCEP ENSEMBLE MEAN PLOT SUGGEST THAT A DEEP UPPER LOW WILL REMAIN ANCHORED OVER THE NORTHEASTERN U.S. FOR THE REMAINDER OF THE FORECAST PERIOD...WITH WEST TO NORTHWEST FLOW ALOFT OVER SOUTH FLORIDA. THUS...EXPECT DRY AND SEASONABLY COOL WEATHER TO PERSIST FROM THURSDAY INTO NEXT WEEKEND. && .AVIATION... HIGH LEVEL CIRRUS CONTINUES TO STREAM NE ACROSS SOUTH FLORIDA WHICH WILL BE SCATTERED TO BROKEN AT TIMES THROUGH THE DAY. FORECAST SOUNDINGS INDICATE DRY AIR IN THE BOUNDARY LAYER...HOWEVER DEEP MIXING MAY ALLOW FOR SCT CU TO FORM IN THE 4-5K FOOT RANGE DURING THE AFTERNOON HOURS. ONLY PROBLEM FORESEEN AT THIS TIME IS SOME PATCHY FOG AROUND THE KTMB AREA...BUT THIS SHOULD BURN OFF RELATIVELY QUICKLY. && .MARINE... TRANQUIL MARINE CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE BEGINNING OF NEXT WEEK...DESPITE STRONGER NORTHERLY FLOW ALLOWING GULF STREAM SEAS TO BUILD SLIGHTLY ON SUNDAY. STRONGER SOUTHERLY/SOUTHWESTERLY WINDS TOWARD THE MIDDLE OF NEXT WEEK WILL PRESENT THE GREATEST CONCERN...WITH SEAS LIKELY APPROACHING 6 FEET BY WEDNESDAY. && .FIRE WEATHER... GREATEST SHORT TERM CONCERN WILL COME THIS AFTERNOON ACROSS INTERIOR LOCATIONS WITH A DRY AIRMASS PRESENT AT THE SURFACE AND AT LEAST SOME POTENTIAL FOR DEEPER MIXING OF DRY AIR FROM ALOFT. A RED FLAG WARNING WILL LIKELY BE NEEDED FOR PORTIONS OF THE AREA...AND WILL ADDRESS IN THE FIRE WEATHER PRODUCTS LATER THIS MORNING. AFTER TODAY...ONSHORE FLOW AND INCREASING AMOUNTS OF BOUNDARY LAYER MOISTURE WILL LIMIT THE FIRE WEATHER THREAT UNTIL THE END OF NEXT WEEK WHEN DRY AIR WILL ONCE AGAIN SPREAD SOUTHWARD BEHIND A COLD FRONT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 77 57 75 64 / - 10 10 10 FORT LAUDERDALE 78 61 76 67 / - 10 10 10 MIAMI 80 61 77 67 / - 10 10 20 NAPLES 74 56 74 59 / - - - 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ LONG TERM...70/DD SHORT TERM...65 AVIATION...65 UPDATE...TINGLER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 855 PM CST SUN FEB 11 2007 .DISCUSSION... UPDATING THE FORECAST AROUND 915 PM TO REMOVE SLIGHT CHANCE OF LIGHT SNOW SOUTH OF I-74 WITH JUST SLIGHT CHANCE OF LIGHT SNOW OR FLURRIES FROM I-74 NORTH. BEST CHANCE OF LIGHT SNOW TONIGHT WILL BE ALONG AND NORTH OF I-80 ACROSS NORTHERN IL WERE A COUPLE INCHES OF SNOW COULD ACCUMULATE ESPECIALLY NEAR THE WI BORDER. 02Z/8 PM SURFACE MAP SHOWS 1028 MB HIGH PRESSURE OVER WV WHILE 1008 MB LOW PRESSURE OVER SOUTHERN QUEBEC WITH ITS COLD FRONT EXTENDING ACROSS FAR NORTHERN LOWER MI...NORTHERN WI AND SOUTHERN MN. MID AND HIGH CLOUDS SPREAD EAST ACROSS IL AND INTO INDIANA BY MID EVENING. 8 TO 10 KFT CEILINGS FROM PEORIA AND SPRINGFIELD WEST. LIGHT SNOW WAS ACROSS NORTHERN IOWA AND SW WI NORTH OF I-80 AND MOVING EAST TOWARD NORTHERN IL. TEMPS RANGE FROM THE 20S FROM I-74 NORTH TO THE LOWER 30S FROM GALESBURG...SPRINGFIELD...MATTOON AND TERRE HAUTE SW. DEWPOINTS WERE IN THE MID TEENS TO AROUND 20F. MOST AREAS GOT ABOVE FREEZING THIS AFTERNOON WITH HIGHS IN THE LOWER 30S FROM I-74 NORTH TO THE LOWER 40S FROM SPRINGFIELD AND LAWRENCEVILLE SW. RUC AND WRF KEEP LIGHT SNOW NORTH OF GALESBURG AND LACON AND ISENTROPIC SURFACES SHOW THE LOWER PRESSURE CONDENSATION DEFICITS NORTH OF I-74 TONIGHT AND SHIFTING NORTH OF I-80 OVERNIGHT. SO JUST HAVING SLIGHT CHANCE OF LIGHT SNOW OR FLURRIES FROM I-74 NORTH AND DRY CENTRAL AND SE IL. SE WINDS UNDER 10 MPH BUT MOSTLY CLOUDY SKIES TO KEEP TEMPS FROM COOLING TOO MUCH MORE WITH LOWS AROUND 20F IN EAST CENTRAL IL AND AROUND 25F FROM GALESBURG TO SPRINGFIELD TO LAWRENCEVILLE SW. MODELS TRENDING SLOWER WITH STORM SYSTEM DEVELOPING OVER THE FRONT RANGE OF THE ROCKIES AND DEEPENING LOW PRESSURE INTO NORTH TX/SW OK MON. QPF MOVING INTO SW HALF DURING MON AFTERNOON AND COULD BE WARM ENOUGH FOR RAIN MON AFTERNOON ESPECIALLY SE IL WHERE TEMPS UPPER 30S TO NEAR 40F. GFS IS COLDER AND FASTER WITH QPF THAN WRF MODEL WHICHS WAITS UNTIL MON NIGHT TO BRING IN QPF AND LIGHTER FROM THE IL RIVER NW. && .PREV DISCUSSION... LATEST SURFACE ANALYSIS HAD HIGH PRESSURE CENTERED OVER THE SOUTHEAST UNITED STATES. MEANWHILE...A CLIPPER SYSTEM WAS OVER THE ONTARIO/QUEBEC BORDER...WITH A COLD FRONT EXTENDING SOUTHWEST INTO THE UPPER MIDWEST. ALSO...WEAK LOW PRESSURE WAS JUST IN THE LEE OF THE ROCKIES...WITH A WARM FRONT EXTENDING NORTHEAST TO CONNECT WITH THE UPPER MIDWEST COLD FRONT. ALOFT...A POLAR VORTEX WAS CENTERED OVER NORTHERN ONTARIO...WITH WEAK UPPER RIDGING EXTENDING FROM THE GULF COAST OF TEXAS TO THE PACIFIC NORTHWEST. ALSO...A VIGOROUS WAVE WAS COMING ONSHORE ALONG THE CALIFORNIA COAST. MAIN FORECAST CONCERN THE NEXT FEW DAYS REVOLVES AROUND INTERACTION OF THE UPPER VORTEX...APPROACHING UPPER WAVE...AND STRONG THERMAL GRADIENT ACROSS THE NATION/S MID SECTION. THESE FEATURES ARE EXPECTED TO BRING REGION AN EXTENDED PERIOD OF WINTRY PRECIPITATION EARLY THIS WEEK. 12Z MODELS IN GOOD AGREEMENT WITH MOST MAJOR FEATURES...THOUGH SUBTLE IMPORTANT DIFFERENCES PERSIST IN QPF AMOUNT AND MAX/MIN AXES AS WELL AS LOW LEVEL THERMAL PROFILE. THE MODELS HAVE ALSO CONTINUED TO SLOW THE APPROACH OF THE WEST COAST WAVE...MAKING THE CURRENT EXPECTED ONSET OF THE HEAVIER PRECIPITATION ABOUT 24 HOURS LATER THAN PROGS OF ONLY A COUPLE DAYS AGO. DUE TO THIS LINGERING UNCERTAINTY ON THE DETAILS...CONTINUED SLOWING IN THE MODELS...AND AT LEAST A 24 HOUR TIME PERIOD BEFORE SIGNIFICANT PRECIPITATION ARRIVES...WE AND SURROUNDING OFFICES HAVE OPTED TO LEAVE GOING WATCH UNCHANGED. SHORT TERM...TONIGHT THROUGH WEDNESDAY... TONIGHT...AS STATED ABOVE...WEST COAST WAVE WILL BE SLOW TO ARRIVE AND FRONT TO THE NORTH WILL BE MOISTURE STARVED AS IT DROPS IN TONIGHT. INITIAL...MODEST WAA/ISENTROPIC LIFT AHEAD OF APPROACHING WAVE SHOULD ONLY YIELD AN INCREASE IN CLOUDS. HAVE LOWERED PRECIPITATION CHANCES CONSIDERABLY AND RESTRICTED THOSE THAT REMAIN TO THE OVERNIGHT HOURS. MONDAY THROUGH TUESDAY...THE MAIN EVENT. SURFACE BOUNDARY SINKS TO THE OHIO VALLEY BY MONDAY AFTERNOON...A POSITION IT WILL MAINTAIN UNTIL MAIN SYSTEM PASSES BY LATER TUESDAY. WAA/ISENTROPIC LIFT WILL CONTINUE/INCREASE TO THE NORTH OF THE BOUNDARY WITH TIME MONDAY AND SHOULD ALLOW PRECIPITATION TO BREAK OUT ACROSS MOST LOCATIONS BY LATE MONDAY AFTERNOON. THERMAL PROFILES SUPPORT SNOW ACROSS MOST OF FORECAST AREA...BUT AREAS SOUTH OF I-70 WILL LIKELY BE WARM ENOUGH FOR SLEET OR RAIN. SURFACE TEMPERATURES SOUTH OF I-70 SHOULD ALSO BE JUST ABOVE FREEZING SO ICE IS NOT CONSIDERED A MAJOR THREAT UNTIL MONDAY EVENING. DUE TO THE LATE ONSET OF PRECIPITATION...SIGNIFICANT ACCUMULATIONS OF ANY PRECIPITATION TYPE ARE NOT EXPECTED TO BEGIN UNTIL MONDAY NIGHT. MAIN UPPER WAVE AND ASSOCIATED SURFACE LOW ARE EXPECTED TO MOVE FROM THE CENTRAL PLAINS BY EARLY MONDAY EVENING...TO THE CENTRAL OHIO VALLEY BY TUESDAY EVENING. STRONG FORCING WILL PASS THROUGH FORECAST AREA FROM MONDAY EVENING INTO MIDDAY TUESDAY. THIS FORCING WILL INITIAL COME FROM PERSISTENT ISENTROPIC LIFT AND TRANSITION MORE TO STRONG MID LEVEL FRONTOGENESIS WITH TIME. THE TIGHTENING OF THE ALREADY SUBSTANTIAL BAROCLINIC ZONE WILL OCCUR COURTESY OF STRONG UPPER DIVERGENCE FROM A COUPLED JET PASSING NEARLY OVERHEAD. THE EXACT PLACEMENT OF THE HEAVIEST SNOW ACCUMULATION IS STILL A TOUGH CALL. HOWEVER...THE CHANCE THAT HEAVY ACCUMULATIONS WILL OCCUR IS LOOKING PRETTY GOOD. THE AMPLE FORCING MENTIONED ABOVE WILL ALSO HAVE SIGNIFICANT MOISTURE TO WORK WITH. PRECIPITABLE WATER VALUES ACROSS MOST OF FORECAST AREA WILL AVERAGE ONE HALF TO THREE QUARTERS OF AN INCH DURING THE FAVORED PRECIPITATION PERIOD. LOOKING AT IT ANOTHER WAY...MIXING RATIOS WILL AVERAGE 3 TO 4 G/KG DURING THE UP TO 12 HOURS OF MODEST TO STRONG ISENTROPIC LIFT WHICH COULD YIELD 6 TO 8 INCHES OF SNOW. SOUTH OF I-70...THERMAL PROFILES SUPPORT PERIODS OF SLEET AND POSSIBLY FREEZING RAIN AS WELL AS THE MAXIMUM TEMPERATURE IN THE ELEVATED WARM LAYER WILL AVERAGE 2-3 C THROUGH MONDAY NIGHT. THE SNOW WILL BEGIN TO TAPER OFF TUESDAY AS THE DEFORMATION ZONE IN THE WAKE OF THE SYSTEM PULLS AWAY. HOWEVER...STIFF NORTHEAST WINDS WILL CAUSE BLOWING AND DRIFTING OF THE NEWLY FALLEN SNOW. HOWEVER... WINDS ARE NOT EXPECTED TO BE STRONG ENOUGH TO PRODUCE BLIZZARD CONDITIONS. WEDNESDAY...QUIET AND COLD CONDITIONS RETURN AS ANOTHER ARCTIC HIGH STARTS TO BUILD IN. TEMPERATURES THROUGH THE REST OF THE WEEK CERTAINLY HAVE THE POTENTIAL TO BE COLDER THAN CURRENT FORECAST. HOWEVER...THIS WILL BE LARGELY DEPENDANT ON WHERE AND HOW MUCH SNOW FALLS OVER THE NEXT COUPLE OF DAYS. LONG TERM...THURSDAY THROUGH SUNDAY...MODELS/ENSEMBLES IN PRETTY GOOD AGREEMENT WITH THE GENERALLY QUIET/UNSEASONABLY COOL CONDITIONS EXPECTED THROUGH THE PERIOD. AN ARCTIC SURFACE HIGH WILL SLOWLY BUILD THROUGH THE REGION FROM THE NORTHWEST...WHILE A COMPLEX POLAR VORTEX CONTINUES TO WOBBLE OVER EASTERN CANADA. SOME IMPULSES ARE EXPECTED TO ARRIVE BY THE WEEKEND IN THE PERSISTENT NORTHWEST UPPER FLOW...BUT THE MODEL DIFFERENCES IN THESE SMALL SCALE FEATURES PRECLUDE ADDING A MENTION OF SNOW AT THIS TIME. HOWEVER...THIS WILL NEED TO BE WATCHED CLOSELY OVER THE NEXT FEW DAYS. && .ILX WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH IN EFFECT FOR ENTIRE ILX CWA FROM 18Z MONDAY TO 00Z WEDNESDAY. && $$ HUETTL/BAK il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 239 PM MST SUN FEB 11 2007 .SHORT TERM... (TONIGHT - WEDNESDAY) LATEST SURFACE MAP ANALYSIS SHOWED HIGH PRESSURE RIDGE CENTERED OVER ILLINOIS WITH A STATIONARY FRONT OVER EASTERN COLORADO AND EASTERN NEW MEXICO. LATEST IR AND WATER VAPOR SATELLITE IMAGERY SHOWED CYCLONIC SPIN AND EASTWARD PROGRESSION OF STRONG SHORTWAVE AND TROUGH NOW MOVING INTO THE ROCKIES FROM IDAHO THROUGH NEVADA INTO WESTERN ARIZONA. LIGHTNING STRIKES HAVE ALSO BEEN SEEN WITH THIS SYSTEM THIS AFTERNOON. MAJOR FORECAST CONCERNS IN THE SHORT TERM INCLUDE THE POSSIBILITY OF MORE FREEZING FOG TONIGHT AND THEN PRECIPITATION TYPES AND AMOUNTS TOMORROW AND TOMORROW NIGHT WITH TROUGH TO OUR WEST. FOR TONIGHT A SURFACE LOW PRESSURE SYSTEM DEVELOPS IN SOUTHEAST COLORADO. WILL STILL HAVE LOTS OF BOUNDARY LATER RH AS SEEN ON LATEST RUC SOUNDINGS. WILL CARRY MENTION OF LIGHT FREEZING DRIZZLE AND FOG ENTIRE FORECAST AREA UNTIL MIDNIGHT THEN FREEZING DRIZZLE AND FREEZING FOG MUCH OF FORECAST AREA WITH SLIGHT CHANCE OF FLURRIES IN FAR NORTHWEST AND SLIGHT CHANCE OF LIGHT SHOWERS AFTER MIDNIGHT WITH THE LIGHT FREEZING DRIZZLE EAST TO WEST ACROSS THE MIDDLE OF THE FORECAST AREA. WILL GO WITH LOW TEMPERATURES RANGING FROM LOW 20S NORTHWEST TO LOW 30S SOUTH AND EAST. THEN MONDAY AND MONDAY NIGHT BECOME QUITE INTERESTING. SURFACE LOW DEEPENS AS IT MOVES NORTHEAST ACROSS SOUTHWEST AND CENTRAL KANSAS ALONG WITH IMPRESSIVE SHORTWAVE TROUGH. LOOKING AT NAM AND GFS MODEL SOUNDINGS LOOKS LIKE PRECIPITATION TYPE WILL BE A CONCERN ACROSS THE REGION WITH A MIXTURE OF TYPES TO BEGIN WITH. PRIOR TO 18Z WILL PLAN TO CARRY AREAS OF FREEZING DRIZZLE AND CHANCE OF LIGHT SNOW SHOWERS NORTHWEST HALF OF FORECAST AREA WITH AREAS OF FREEZING DRIZZLE AND SLEET SOUTHEAST HALF. AFTER 18Z DURING THE AFTERNOON WILL SEE COLDER AIR BEING DRAWN AROUND ON THE BACKSIDE OF THE LOW AND TROUGH WHICH SHOULD CHANGE OVER ALL PRECIPITATION TO A FROZEN VARIETY. WILL GO WITH COLD HIGH TEMPERATURES RANGING FROM THE MIDDLE 20S FAR NORTH TO LOWER 30S SOUTH THROUGH EAST. FOR MONDAY NIGHT WILL CONTINUE CHANCES FOR LIGHT SNOW ACROSS THE ENTIRE AREA WITH LOWER CHANCES WEST TO EAST AFTER MIDNIGHT AS SYSTEM MOVES ON TO THE EAST AND AWAY FROM OUR AREA. WILL EXPECT TO SEE SOME SNOW BY THE TIME ALL IS DONE. AT THIS TIME ONLY EXPECTING ACCUMULATIONS OF PERHAPS 1 TO 2 INCHES CAN BE EXPECTED WITH HIGHEST AMOUNTS FROM THE HILL CITY TO TRIBUNE AREAS. WILL GO CLOSE TO GUIDANCE FOR COLD LOW TEMPERATURES IN THE TEENS AND SINGLE DIGITS. FOR TUESDAY THROUGH WEDNESDAY WILL SEE A DRY PERIOD ON TUESDAY BEFORE THE NEXT WEAKER TROUGH MOVES THROUGH THE REGION TUESDAY NIGHT AND WEDNESDAY. LOOKS LIKE A LITTLE MOISTURE AND DYNAMICS WITH WHICH THIS SYSTEM CAN USE. HAVE KEPT SLIGHT CHANCE MENTION FOR LIGHT SNOW FOR TUESDAY NIGHT INTO WEDNESDAY. DID NOT CHANGE TEMPERATURES MUCH AT ALL FOR TUESDAY THROUGH WEDNESDAY AS COLD AIR STILL IN PLACE. .LONG TERM... (THURSDAY THROUGH SUNDAY) UPPER RIDGE PRESENTLY OVER WEST COAST WILL SLIDE SLOWLY EASTWARD AND MAINTAIN A PERIOD OF DRY WEATHER INTO NEXT WEEKEND. ALSO TEMPERATURES LOOK TO WARM UP AS WELL WITH HIGHS RISING INTO THE 40S AND LOWS IN THE TEENS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ LAMMERS ks AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE GOODLAND KS 1030 AM MST SUN FEB 11 2007 .DISCUSSION...JUST COMPLETED ANOTHER UPDATE. MAIN REASON WAS TO DROP THE FREEZING FOG ADVISORY. VERY COMPLICATED AND TEDIOUS SITUATION FOR TODAY. CLOUDS HAVE CLEARED FROM THE WEST. HOWEVER...THE CLEARING DOES NOT LOOK LIKE IT WILL MOVE MUCH FURTHER SOUTH AND EAST THAN RIGHT NOW. MODELS DO NOT HAVE SURFACE TROUGH TO OUR WEST STRONG ENOUGH AS EVIDENCED BY THE STRONGER WINDS NEAR THE KANSAS AND COLORADO BORDER. ALSO BECAUSE OF THE POSITION AND STRENGTH OF TROUGH...WINDS ARE GOING TO BE SOUTH AND SOUTHEAST THAN CURRENTLY EXPECTED. THAT IS WHY CLEARING LINE WILL NOT PROGRESS MUCH FURTHER AND ALSO WHY HAVE INCREASED WIND SPEEDS. BOUNDARY LAYER RH STAYS VERY HIGH IN THE SOUTH AND EAST. THAT WILL KEEP OVERCAST SKIES THERE. RUC40 AND RUC13 WHICH DID BETTER ON STRATUS AND FOG POSITION AND RETURN YESTERDAY...BRING FOG AND STRATUS BACK RAPIDLY IN THE SOUTHWEST LATER THIS AFTERNOON. SO KEPT A MENTION OF PATCHY FOG IN THE SOUTH AND EAST. WILL PROBABLY NEED FOG PUT IN THE FORECAST FOR THIS EVENING/TONIGHT IN ADVANCE OF PRECIPITATION. WILL BE TALKING WITH THE DAY FORECASTER AND MONITOR TRENDS TO MAKE A LATER DECISION ON THAT. THERE IS SOME MIDDLE AND HIGH LEVEL CLOUD COVER MOVING THROUGH WHICH COMPLICATES HIGH TEMPERATURE FORECAST EVEN MORE. BECAUSE OF THE CLEARING THAT HAS TAKEN PLACE AND CURRENT TEMPERATURES...RAISED HIGH TEMPERATURES FOR THE DAY...ESPECIALLY IN THE COLORADO PORTION OF OUR AREA. THINK THAT IS ALL. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 229 PM MST SAT FEB 10 2007 .SHORT TERM... (TONIGHT - TUESDAY) FORECAST CONCERNS FOR THE SHORT TERM INCLUDE MORE FREEZING FOG ALONG WITH TEMPERATURES AND CHANCES FOR SNOW SUNDAY NIGHT INTO MONDAY. LATEST SURFACE MAP SHOWS AXIS OF HIGH PRESSURE RIDGE FROM IOWA TO TEXAS WITH STATIONARY FRONT DRAPED ACROSS CENTRAL COLORADO AND EASTERN NEW MEXICO. LATEST IR AND WATER VAPOR SATELLITE IMAGERY SHOWS CYCLONIC SPIN ASSOCIATED WITH TROUGH APPROACHING THE WEST COAST. SEVERAL OTHER SIMILAR FEATURES WERE SEEN FURTHER WEST OVER THE EASTERN PACIFIC. HUGE HUDSON BAY LOW STILL SPINNING IN PLACE NORTH OF THE GREAT LAKES. COLD ARCTIC AIR STILL ENTRENCHED ACROSS THE GOOD LAND FORECAST AREA WITH LITTLE CHANGE OVER THE PAST SEVERAL DAYS WITH REGARD TO LOW STRATUS AND FREEZING FOG EPISODES. MODELS WERE IN GOOD AGREEMENT TODAY IN THE SHORT TERM WITH REGARD TO SURFACE FEATURES AS WELL AS WITH THE POSITION AND MOVEMENT OF TROUGH OFF WEST COAST WHICH WILL BEGIN AFFECTING OUR WEATHER BY LATE SUNDAY INTO MONDAY. PREFERRED THE GFS MODEL SLIGHTLY BETTER THAN THE REST AS IT WAS DOING LITTLE BETTER WITH TIMING AND POSITION OF SYSTEMS AS WELL AS WITH FORECAST TEMPERATURE FIELDS. FOR TONIGHT LATEST RUC MODEL STILL SHOWED DECENT SWATH OF HIGH BOUNDARY LAYER RH VALUES AND DEEP MOISTURE WITH LIGHT WINDS WHICH SHOULD SET THE STAGE FOR ANOTHER FOGGY NIGHT. WILL CARRY AREAS OF FREEZING FOG. FOR LOW TEMPERATURES WILL GO CLOSE TO GUIDANCE FOR LOWS SIMILAR TO PREVIOUS COUPLE OF NIGHTS IN THE LOWER TO MIDDLE 20S. SUNDAY SHOULD SEE FREEZING FOG FOR THE MORNING BEFORE BURNING OFF BY MIDDLE OF THE DAY. WILL STILL HAVE CANOPY OF STRATUS CLOUDS IN PLACE AS WELL. 850 MB TEMPS OF SHORT RANGE MODELS ATTEMPT TO WARM UP THE REGION FROM PREVIOUS DAY AND EXPECT SOME WARMING TO OCCUR. TEMPERATURES DO HOWEVER REMAIN SOMEWHAT PROBLEMATIC AS WE STILL HAVE OUR SNOW COVER IN PLACE. WILL GO WITH HIGH TEMPERATURES MOSTLY IN THE MIDDLE 30S. A SHORTWAVE TROUGH OFF THE WEST COAST WILL BE APPROACHING SUNDAY NIGHT AND THEN MOVE THROUGH THE AREA MONDAY AND MONDAY NIGHT. MODELS DO SHOW SOME REALLY DECENT LIFT AND INSTABILITY WITH THIS SYSTEM. APPEARS WE WILL HAVE A CHANCE FOR SOME LIGHT SNOW SUNDAY NIGHT WITH BEST CHANCES DURING THE DAY ON MONDAY. HAVE INCREASED POPS A BIT FOR MONDAY INTO THE 40 TO 50 PERCENT RANGE. HAVE ALSO MAINTAINED CHANCE POPS INTO MONDAY NIGHT AS SYSTEM EXITS THE REGION. MODELS ALSO SHOW A SLUG OF COLDER AIR TO MOVE INTO REGION WITH TROUGH PASSAGE. WILL GO WITH HIGH TEMPERATURES MONDAY IN THE UPPER 20S AND LOWER 30S WHILE LOW TEMPERATURES MONDAY NIGHT FALL INTO THE LOWER TO MIDDLE TEENS. FOR TUESDAY WILL BE BETWEEN SYSTEMS BEFORE NEXT SHORTWAVE TROUGH APPROACHES AND MOVES THROUGH. WILL KEEP TUESDAY DRY AND MOSTLY CLOUDY. WILL KEEP HIGH TEMPERATURES COLD MAINLY IN THE MIDDLE 20S. BY TUESDAY NIGHT EXPECT SYSTEM TO BE CLOSE ENOUGH WITH ENOUGH MOISTURE AND DYNAMICS TO BEGIN TO PRODUCE SMALL CHANCE OF LIGHT SNOW. EXPECT LOW TEMPERATURES TO REMAIN COLD IN THE TEENS AND SINGLE DIGITS. .LONG TERM... (WEDNESDAY - SATURDAY) IN THE LONG TERM MODELS WERE ALL OVER THE PLACE WITH REGARD TO EXACT TRACK OF THE NEXT SHORTWAVE TROUGH TO PASS THROUGH THE FORECAST AREA. CURRENTLY TRACK LOOKS TO BE MORE TO OUR SOUTH. MODELS DO ALSO HINT AT A SURFACE LOW PRESSURE AREA TO DEVELOP NEARBY TO OUR SOUTH ON WEDNESDAY. AT THIS TIME ENOUGH CONFIDENCE WAS HAD TO CONTINUE TO MENTION A CHANCE FOR LIGHT SNOW DURING THE DAY ON WEDNESDAY. KEPT THE REST OF THE FORECAST THROUGH SATURDAY DRY AS HIGH PRESSURE BUILDS BACK INTO THE REGION AND DRIES OUT THE ATMOSPHERE. TEMPERATURES WILL BE COLD FOR WEDNESDAY AND THURSDAY WITH A LITTLE WARMING ON FRIDAY. THEN ANOTHER SURGE OF COLD AIR LOOKS TO RETURN TO THE FORECAST AREA BY NEXT WEEKEND. FUTURE SHIFTS WILL NEED TO WATCH THE EXTENDED MODELS CLOSELY FOR BETTER TIMING AND TRACK OF THESE FEATURES NEXT WEEK. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ LAMMERS ks AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE GOODLAND KS 1157 AM MST SAT FEB 10 2007 .DISCUSSION...JUST COMPLETED ANOTHER UPDATE. CLEARING IS OCCURRING FROM THE WEST AND QUESTION IS HOW FAR EAST DOES IT GET. BOUNDARY LAYER MOISTURE FORECASTS FROM RUC/NAM MATCHING UP WELL WITH REALITY. GOING TO BE AN EXTREMELY TIGHT GRADIENT OVER THE COLORADO COUNTIES TO NEAR THE KANSAS AND COLORADO BORDER. CLOUD COVER HANGING ON TOUGH AND ACTUALLY THICKENING OVER THE REST OF THE AREA. SO BLEND OF REALITY AND RUC/NAM SHOULD WORK OUT FINE. ALSO WILL HAVE TO EXTEND THE FOG THROUGH THE AFTERNOON OVER MOST OF THE AREA. WHERE LOW LEVEL MOISTURE AXIS IS FORECAST TO BE ACCORDING TO THE RUC/NAM...WILL KEEP AREAS OF FOG. KMCK HAS ACTUALLY DROPPED IN VISIBILITY RECENTLY SO LOOKS LIKE THIS WILL WORK. WILL HAVE PATCHY FOG ON THE BORDER OF THIS AREA WITH THE EXTREME EAST AND NORTHWEST SECTION WITH NO FOG...HOPEFULLY. FOG LOOKS TO RAPIDLY REDEVELOP IN THE SOUTHWEST IF BELIEVE THE RUC. NAM12 DOING VERY WELL WITH THE WIND FIELD...AND UPDATED THIS AFTERNOON WITH IT. ADJUSTED MAX TEMPERATURES DOWN IN THE EAST SLIGHTLY WHERE PERSISTENT FOG AND STRATUS WILL CONTINUE. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ BULLER ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1045 PM EST SUN FEB 11 2007 .UPDATE... UPDATE FOCUSES ON LES TRENDS. LATEST MQT RADAR LOOP SHOWS DOMINANT LES BAND WHICH FORMED ALONG WIND SHIFT LINE HAS SAGGED SE ALONG SHOT POINT-MUNISING LINE. STILL SOME REFLECTIVITIES EXCEEDING 30 DBZ WITHIN THIS NARROW BAND AND WOULD NOT BE SURPRISED IF SNOWFALL RATES ARE EXCEEDING AN INCH/HOUR AS IT PASSES. QUESTIONS FOR OVERNIGHT WILL BE WHETHER OR NOT THIS BAND WILL PERSIST IN INTENSITY OR IF ANOTHER BAND WILL REFORM OVER ERN ALGER AND NRN SCHOOLCRAFT COUNTIES IN AREA OF ENHANCED LOW-LEVEL CONVERGENCE AS DEPICTED BY 00Z MESOSCALE MODELS (RUC13, NAM12, AND WRF-ARW). GIVEN THAT THE BAND APPEARS TO BE DIMINISHING SOMEWHAT ALONG ITS WESTERN EXTENT...IT LOOKS LIKE MESOSCALE MODELS MIGHT HAVE RIGHT IDEA. SO WOULD LOOK FOR CURRENT BAND TO EITHER PROPAGATE BACK EAST OR REFORM OVER ERN ALGER AND NRN SCHOOLCRAFT LATER TONIGHT AS LAND BREEZES HELP FOCUS LOW-LEVEL CONVERGENCE OVER THIS AREA. KEPT IN ADDITIONAL AMTS OF 1-3 INCHES FOR ALGER COUNTY IN THE OVERNIGHT PERIOD. ALSO TRIMMED BACK LES COVERAGE FM NUMEROUS TO SCATTERED ALONG MQT COUNTY LAKESHORE AREA GIVEN THAT BETTER CONVERGENCE WILL TEND TO BE FOCUSED FARTHER E. OTHER CHANGE WAS TO TRIM BACK POPS OVER WRN COUNTIES AS VERY DRY AIR UPSTREAM AND ANTICYCLONIC FLOW HAVE BASICALLY DIMINISHED LES TO FLURRIES THERE AS NOTED ON IR SATELLITE IMAGERY. && .SHORT TERM (TONIGHT AND MONDAY)... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD VORTEX CENTERED IN THE VCNTY OF JAMES BAY AND A RIDGE EXTENDING FROM THE SRN ROCKIES TO THE NE GULF OF ALASKA. RESULT IS NW FLOW DOMINATING THE GREAT LAKES REGION. MAIN FEATURE OF INTEREST IN THE SHORT TERM IS A SHEARED SHORTWAVE DROPPING SE ACROSS MANITOBA/ONTARIO. AT THE LOW LEVELS... CONVERGENT WRLY FLOW OVER WRN LAKE SUPERIOR HAS LED TO MAIN ZONE OF LES ACROSS N HALF OF HOUGHTON COUNTY THIS AFTN. HOWEVER...THE GENERALLY DRY UPSTREAM AIRMASS PER 12Z KINL SOUNDING HAS LARGELY KEPT LES IN CHECK. 19Z TAMDAR SOUNDING FROM KCMX LOOKED MORE SUPPORTIVE OF DECENT LES THOUGH WITH INVERSION AT 830MB (5.4KFT)... SO THERE MIGHT BE SOME LOCALIZED HEAVIER SNOW BURSTS OCCURRING. OVER ERN LAKE SUPERIOR...LES HAS UNDERGONE SOME REORGANIZATION THIS AFTN...AND THE EXPECTED HVY BAND OF LES ALONG WIND SHIFT HAS FINALLY TAKEN SHAPE FROM NEAR THE HURON ISLANDS TO GRAND MARAIS. BAND IS VERY NARROW...BUT 0.5 DEGREE REFLECTIVITY IMAGERY FROM KMQT RADAR IS SHOWING INCREASING AREA OF GREATER THAN 28DBZ ECHOES. SO 1-3 INCH/HR SNOW RATES ARE PROBABLY COMMON IN THIS NARROW BAND OF SNOW. AS SHORTWAVE MENTIONED ABOVE CONTINUES SHEARING SE THIS EVENING... SYNOPTIC ENHANCEMENT TO LES WILL END EARLY THIS EVENING AS INDICATED BY DEEP LAYER QVECTOR CONVERGENCE SHIFTING E OF THE AREA. THIS FORCING LATE AFTN/EARLY EVENING WILL ASSIST THE MAIN BAND OF LES ON WIND SHIFT WHICH IS DROPPING THRU SCNTRL/SE LAKE SUPERIOR ATTM. COULD SEE A QUICK 2-3INCHES OF SNOW FROM THIS LES BAND PROVIDED IT DOES NOT BECOME NEARLY STATIONARY. FEEL CONFIDENT THAT WIND SHIFT WILL PROGRESS STEADILY THRU ERN ALGER/LUCE COUNTIES THIS EVENING WHICH WOULD KEEP BAND ON THE MOVE AND LIMIT ACCUMULATIONS. FARTHER W...WILL NEED TO KEEP AN EYE ON WRN ALGER COUNTY. AS WINDS BECOME NW...LAND BREEZE OFF HURON MOUNTAINS COULD RESULT IN THE TAIL END OF THIS BAND BECOMING STATIONARY FROM AROUND BIG BAY TOWARD THE AREA FROM SHOT POINT TO MUNISING. OTHERWISE...WITHOUT FOCUSED CONVERGENCE...LES THRU THE NIGHT SHOULD BE ON THE LIGHT SIDE (GENERALLY 1-3 INCHES) WITH INVERSION SETTING UP AROUND 4KFT. OUT W...LES SHOULD BECOME SCT OVER THE KEWEENAW AS WINDS VEER NNW WITH ISLE ROYALE LIMITING FETCH. LES SHOULD BECOME FOCUSED FARTHER S INTO ONTONAGON/GOGEBIC COUNTIES. ICE COVER EXTENDS FROM THE APOSTLE ISLANDS TO NEAR THE LOCATION OF WRN LAKE SUPERIOR BUOY. ALTHOUGH THE ICE COVER IS NOT SOLID...IT WILL WORK TO LIMIT HEAT/MOISTURE FLUXES AND WILL HAVE SOME IMPACT ON LES COVERAGE INTO GOGEBIC COUNTY. HAVE THUS CONFINED NUMEROUS SHSN COVERAGE TO ONLY A SMALL PART OF THE COUNTY N OF KIWD. AS FOR TEMPS...LOWERED MINS INLAND TONIGHT A FEW DEGREES WITH A BIT LESS CLOUD COVER THAN ORIGINALLY EXPECTED. WOULDN`T BE SURPRISED TO SEE -10F OR LOWER AT THE USUAL COLD SPOTS OVER THE INTERIOR W HALF. ON MON...WINDS WILL SLOWLY VEER TO A N TO NE DIRECTION AS SFC HIGH PRES RIDGE BUILDS E ACROSS ONTARIO. HOWEVER...THERE IS LITTLE CHANGE WITH RESPECT TO INVERSION HEIGHTS/MOISTURE PROFILES. SO...LES WILL REMAIN ON THE LIGHT SIDE (SUB ADVY ACCUMULATIONS). THOUGHT ABOUT LOWERING POPS INTO THE CHC CATEGORY OVER THE KEWEENAW...BUT WITH WINDS VEERING N...FETCH WILL ACTUALLY IMPROVE. EVEN SO...WITH A N WIND...THERE WILL BE A TENDENCY FOR DIVERGENCE OVER THE KEWEENAW DUE TO LAND BREEZE COMPONENTS OVER LAND. THIS SHOULD AT LEAST KEEP ACCUMULATIONS LIGHTER THAN WHAT WILL OCCUR FROM ROCKLAND TO THE VCNTY OF THE PORCUPINE MOUNTAINS AND OVER NCNTRL UPPER MI. .LONG TERM (MON NIGHT THROUGH NEXT SUN)... NORTHERLY WINDS AND H85 TEMPS NEAR -20C WILL KEEP LES GOING CLOSE TO LK SUPERIOR. WX MAY GET MORE MUDDLED LATER MON NIGHT INTO TUE AS RUC 13 AND LOCAL WRF-ARW INDICATE LAND BREEZES BEGIN TO DOMINATE LOWER LEVEL WINDS. IDEA MAKES SOME SENSE AS TEMPS WILL BE REALLY COOLING OVR FAR EASTERN UPR MI AS WINDS ARE FM NORTHEAST. SOME SCENARIOS EVEN RESULT IN PUSHING ANY LES COMPELTELY OFFSHORE OF NCNTRL AREAS OUT INTO LK SUPERIOR. NOT SURE HOW THIS SETUP WILL PLAY OUT...BUT FOR NOW DID SHOW A RETREATING TREND TO THE LES MON NIGHT INTO TUE AM BEFORE SYNOPTIC FLOW FM N STRENGTHENS AGAIN. AIRMASS IS DRY AS MAIN MOISTURE WILL BE TIED UP TO SIG STORM AFFECTING CNTRL PLAINS INTO OHIO VALLEY DURING THIS TIME. IF THE ASSOCIATED SFC TROUGH WITH THAT LOW COULD PROGRESS FARTHER NORTH...THEN ONGOING LES MAY GET A BOOST. AS IT STANDS NOW...LES SHOULD BE PRETTY MINIMAL WITH INVERSIONS WELL BLO H85. NE WINDS MAKE LES A NON ISSUE OVR LUCE COUNTY...SO LOWERED TEMPS A BIT TO ACCOUNT FOR THE EASTERLY DRAINAGE FLOW OUT OF ONTARIO ALLOWING TEMPS TO PLUMMET. HIGH RESOLUTION GUIDANCE INDICATES TEMPS TOWARD 25 BLO ZERO MON NIGHT OVR FAR EAST. CERTAINLY PLAUSIBLE IN LOCAL COLD SPOTS WHERE SKIES CAN CLEAR AND WINDS BECOME CALM. WHILE LARGE STORM MOVES INTO THE NORTHEAST CONUS...UPR LOW AND POOL OF COLD AIR SINKS ACROSS UPR LAKES BY WED. ON AVERAGE H85 TEMPS FALL TO -20C TO -25C 12Z WED THROUGH 12Z THU. AT SFC...CYCLONIC N/NW FLOW BTWN STRONG LOW OFF OF NEW ENGLAND AND SPRAWLING HIGH OVR CNTRL CANADA INTO PLAINS WILL GENERATE MODERATE LES. LES WILL LIKELY BECOME HEAVY FOR A PERIOD LATER WED INTO THU AS UPR LOW/LARGE SCALE LIFT/10KFT INVERSION/MOISTURE TO 10-15KFT SWEEPS ACROSS UPR GREAT LAKES. NW-N WINDS IN LOWER LAYERS AS ENHANCING FACTORS ARE BOOSTING LES. EXTENDED LIKELY POPS INTO THU NIGHT-FRI NEAR LK SUPERIOR. UPR LOW SHIFTS TOWARD NEW ENGLAND ON FRI WITH WINDS GRADUALLY BACKING TOWARD A WEST DIRECTION BY SAT. CLIPPER SYSTEM LOOKED LIKE IT WAS GOING TO AFFECT UPR LAKES FRI-SAT. NOW...AS MAIN UPR LOW IS TRENDING SLOWER IN EXITING THE CONUS...THAT SYSTEM STAYS WELL TO THE SW OF THE REGION. KEPT SMALL POPS IN AS WEAKER NORTHERN STREAM TROUGH MOVES THROUGH LATE FRI INTO SAT. MORE NW FLOW LES ON SUN. INTERESTING THAT SIGNS ARE BEGINNING TO EMERGE IN LATEST LONG RANGE GUIDANCE THAT A PATTERN CHANGE COULD START TAKING SHAPE 7-10 DAYS OUT. ACCORDING TO GFS/ECMWF LOOKS LIKE MORE TROUGHING DEVELOPS OVR EASTERN PACIFIC AS STRONGER JET SETS UP FARTHER NORTH TOWARD GULF OF AK. THIS LEADS TO RIDGE OVR WEST CONUS AND TROUGH OVR ERN CANADA AND CONUS BOTH BEGINNING TO MOVE EASTWARD. RESULT IS A WARMER PATTERN FOR MUCH OF THE COUNTRY...INCLUDING UPR GREAT LAKES. && .MQT WATCHES/WARNINGS/ADVISORIES... HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. && $$ UPDATE...VOSS SHORT TERM...ROLFSON LONG TERM...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1150 AM EST SUN FEB 11 2007 .UPDATE... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD VORTEX CENTERED OVER ONTARIO AND A RIDGE EXTENDING FROM THE SRN ROCKIES TO THE NE GULF OF ALASKA. RESULT IS NW FLOW DOMINATING THE GREAT LAKES REGION. MAIN FEATURE OF INTEREST TODAY IS A SHEARED SHORTWAVE DROPPING SE ACROSS MANITOBA/ONTARIO. AT THE LOW LEVELS...CONVERGENT WRLY FLOW OVER WRN LAKE SUPERIOR HAS LED TO SOME LOCALLY HEAVIER SNOW BANDS INTO THE KEWEENAW THIS MORNING...BUT THE GENERALLY DRY UPSTREAM AIRMASS PER 12Z KINL SOUNDING HAS KEPT LES IN CHECK. OVER ERN LAKE SUPERIOR...MAIN LES BANDS ARE OFFSHORE OF ERN UPPER MI. HOWEVER... LIGHTER LES WHICH DEVELOPED N OF MUNISING EARLIER THIS MORNING HAS BEEN STREAMING INTO THE LAKESHORE AREAS FROM PICTURED ROCKS E. SHORTWAVE MENTIONED ABOVE WILL CONTINUE SHEARING SE TODAY...BUT IT WILL PROVIDE A PERIOD OF SYNOPTIC FORCING AS INDICATED BY WEAK DEEP LAYER QVECTOR CONVERGENCE. THAT FORCING IS SPREADING ACROSS LAKE SUPERIOR NOW. THUS...EXPECT A BOOST IN LES FOR A TIME. 12Z NAM/RUC SHOW FORCING EXITING THE NW FCST AREA BY 21Z...SO PERIOD OF ENHANCEMENT IS SHORT-LIVED THERE. IN ADDITION...WITH WINDS VEERING FROM W TO NW...BANDS WILL BE SHIFTING AND FETCH WILL BECOME SHORTER. A 1-3 INCH ACCUMULATION FOR THE REST OF TODAY SEEMS REASONABLE FOR THE KEWEENAW BASED ON EXPECTED CONDITIONS. THE HIGHER AMOUNTS SHOULD OCCUR OVER THE HIGHER TERRAIN S OF HOUGHTON WHERE CONVERGENCE WILL BE FOCUSED EARLY THIS AFTN BEFORE SHIFTING FARTHER S. TO THE E...THE BENEFIT OF A LONGER OVERWATER FETCH WILL YIELD HEAVIER SNOW AS BANDS SHIFT S INTO ALGER/LUCE COUNTIES. CONSIDERED HOISTING AN ADVY...BUT IT REALLY APPEARS THAT THERE WILL BE JUST ONE DOMINATE BAND ALONG THE WIND SHIFT. SINCE THE WIND SHIFT WILL BE PROGRESSIVE...DON`T THINK ANY LOCATION IN PARTICULAR WILL BE UNDER THE BAND FOR LONG. IN GENERAL...EXPECT 1 TO 3 INCH ACCUMULATION FOR ALGER/LUCE FOR THE REMAINDER OF TODAY WITH SOME LOCAL 4 INCH AMOUNTS NEAR THE SHORE. MOST OF THE SNOW WILL FALL E OF MUNISING TODAY. ELSEWHERE...SNOW SHOWERS WILL SPREAD S ACROSS MUCH OF ONTONAGON COUNTY. MIGHT SEE 1 OR 2 INCHES OF ACCUMULATION ACROSS THE NRN PART OF THE COUNTY. SCT -SHSN/FLURRIES WILL ALSO EXPAND INTO SRN HOUGHTON/BARAGA/NW MARQUETTE COUNTIES AS WINDS VEER. ACROSS THE S...A DRY AFTN IS EXPECTED. && .PREV DISCUSSION... ISSUED AT 515 AM EST TAKING A LOOK AT THE WATER VAPOR IMAGERY THIS MORNING AND RUC ANALYSIS...MUCH OF THE NATION WAS UNDER THE INFLUENCE OF HIGH PRESSURE. IN FACT...EASTERN HALF OF THE NATION WAS DOMINATED BY HIGH PRESSURE...CENTERED OVER THE OHIO VALLEY. AN ELONGATED AREA OF LOW PRESSURE WAS SITUATED ALONG THE FRONT RANGE OF THE ROCKY MOUNTAINS...WITH A STATIONARY FRONT STRETCHING FROM NORTHWEST MONTANA...SOUTH AND EASTWARD THROUGH WYOMING...EASTERN COLORADO...AND WESTERN TEXAS. CLOSER TO HOME...BUT ACROSS THE BORDER...AN AREA OF LOW PRESSURE SITUATED ACROSS WESTERN HUDSON BAY AND JAMES BAY. FROM THIS SYSTEM...A RELATIVELY WEAK COLD FRONT STRETCHED WESTWARD OVER SOUTHERN ONTARIO. LOOKING AT THE IR AND WATER VAPOR IMAGERY...SOME CLOUDS WERE EVIDENT ALONG THIS FEATURE...DIMINISHING IN AREAL COVERAGE THE FURTHER WESTWARD TOWARDS MANITOBA YOU GO. LOOKING AT THE WATER VAPOR IMAGERY...AN APPROACHING SHORTWAVE WAS LOCATED FURTHER TO OUR NORTHWEST...ACROSS CENTRAL AND NORTHERN ONTARIO AND MANITOBA. GREATEST CONVERGENCE TODAY STILL LOOKS TO BE OVER THE KEWEENAW PENINSULA BETWEEN 09 AND 18Z. IN FACT...SNOW BEGAN AT CMX SHORTLY BEFORE 08Z. INVERSION HEIGHTS...AND INITIAL DRY ARE OVER THE AREA HAS HINDERED AND SLOWED DOWN THE ONSET OF SNOW OVERNIGHT. OTHERWISE FOR TODAY AND TONIGHT...SURFACE COLD FRONT TO OUR NORTH IS PROGGED TO SLIDE ACROSS THE NORTHERN HALF OF LAKE SUPERIOR BY 18Z...THEN PROGRESS SOUTHWARD AND EXIT THE MNM AREA AROUND OR SHORTLY AFTER 03Z SUNDAY. AS A RESULT...OUR WESTERLY FLOW TODAY WILL VEER NORTHWESTERLY AND THEN NORTHERLY ACROSS THE ENTIRE FORECAST AREA BY MIDNIGHT TONIGHT...USHERING IN COOLER AIR. FOR TEMPERATURES OVERNIGHT TONIGHT...GUIDANCE VALUES FROM THE MET AND MAV DIFFER ACROSS MUCH OF THE CWA BY 6 DEGREES OR SO...WITH THE NAM BEING THE WARMEST DESPITE IT ALSO GIVING FEWER CLOUDS AT THIS TIME PERIOD. WITH SUCH DISCREPANCIES...HAVE LEANED THE TEMPERATURES EVER SO SLIGHTLY TOWARDS THE GFS...COOLING TEMPS 1 TO 4 DEGREES ACROSS THE REGION. THE GFS IS GENERALLY QUICKER AND INITIALLY COOLER TO BRING IN THE COOLER TEMPERATURES ALOFT. THE 00Z/10 NAM DID SEEM TO HAVE SOME PROBLEMS WITH INITIALIZATION. FOR MONDAY...850MB TEMPERATURES ARE EXPECTED TO PLUMMET FROM THE CURRENT -12 TO -14C TO A LOW POINT OF -18C WEST TO -22 TO -24C CENTRAL AND EASTERN LAKE SUPERIOR SHORELINES BY 18Z MONDAY. THE COLDEST AIR WILL STILL REMAIN FURTHER TO OUR NNE...WITH -33C ANTICIPATED OVER EAST CENTRAL ONTARIO. OTHERWISE ON MONDAY...LARGE SURFACE HIGH PRESSURE CENTERED FROM ALBERTA THROUGH CENTRAL MANITOBA WILL BEGIN TO SLOWLY WORK ITS WAY IN FROM THE NORTHWEST...NEVER MAKING IT DIRECTLY OVER THE CWA. A SURFACE LOW OVER NORTHERN TEXAS AND OKLAHOMA WILL BE THE MAIN FOCAL POINT ACROSS THE NATION...LEAVING US WITHOUT SYNOPTIC FORCING TO ASSIST IN SNOW PRODUCTION. INSTEAD...WE WILL CONTINUE TO LOOK TO LAKE SUPERIOR AND TO A LESSER EXTEND LAKE MICHIGAN FOR THE POSSIBILITY OF SNOW...WITH INVERSION HEIGHTS...WIND DIRECTION...AND AVAILABLE MOISTURE BEING KEY...WITH MAINLY LIGHT AMOUNTS ANTICIPATED THROUGH THE PERIOD. BACK TO MONDAY...WINDS BECOME MORE NORTHEASTERLY MONDAY AFTERNOON INTO MONDAY NIGHT...ALLOWING FOR THE BEST CHANCE OF LAKE EFFECT SNOW TO SLIDE WESTWARD OUT OF LUCE COUNTY. HAVE ALSO DECREASED CLOUD COVER TO ACCOUNT FOR THIS ACROSS THE EASTERN THIRD OF THE CWA...FOR MONDAY AND ESPECIALLY MONDAY NIGHT. FOR TUESDAY NIGHT ON...INVERTED TROUGH FROM THE PREVIOUSLY MENTIONED SURFACE LOW SITUATED TO OUR SOUTH WILL STRETCH OVER THE CWA...AND MORE SPECIFICALLY THE EASTERN HALF OF THE CWA THROUGH THURSDAY. LOOKING AT THE 500MB FEATURES...LOOKS LIKE THE 12Z/10 CANADIAN MODEL IS A SLIGHTLY FURTHER SOUTH COMPROMISE BETWEEN THE 00Z/11 RUNS OF THE NAM AND GFS. STILL...JUST ANOTHER REASON TO CONTINUE TO HEDGE THE FORECAST CLOSER TO THE GFS AND FURTHER AWAY FROM THE NAM THROUGH THE PERIOD. WILL CONTINUE TO REVISIT THE LOCATION OF THIS 500MB LOW AS IT WILL PLAY A ROLE IN ENHANCING OUR LAKE EFFECT SNOW...MOISTENING UP THE MID LEVELS && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING E HALF OF LAKE SUPERIOR. HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. && $$ ROLFSON (UPDATE) KF (PREV DISCUSSION) mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1110 PM EST SAT FEB 10 2007 .UPDATE... UPDATE FOCUSED ON HEADLINE FOR LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY OVER THE KEWEENAW PENINSULA. UPSTREAM TAMDAR AND 00Z RAOBS WERE QUITE DRY AT LOW LEVELS WITH INVERSION HGTS AROUND 3KFT. RUC...NAM AND WRF-ARW FCST SNDGS SEEMED TO HAVE A GOOD HANDLE ON DRY AIR AND LOW INVERSION HGTS ALONG WITH CONVERGENCE AREA OFF TIP OF THE KEWEENAW PENINSULA. GIVEN DRYNESS OF SNDGS AND FACT THAT GOOD LOW-LEVEL CONVERGENCE REALLY DOESN`T COME ONSHORE UNTIL AFT 08Z TONIGHT...DO NOT BELIEVE LES WHICH FORMS LATE TONIGHT INTO SUNDAY WILL BE VERY ORGANIZED OR INTENSE. NAM AND RUC FCST SNDGS ALSO SEEM TO SUGGEST THAT LES WILL GENERALLY BE LIGHT AS INVERSION HGTS REMAIN BLO 4KFT. THUS...HAVE CANCELLED THE LES AND BLOWING SNOW ADVISORY OVER THE KEWEENAW PENINSULA. TRIMMED LES AMTS TO 1 TO 2 INCHES LATE TONIGHT WITH ANOTHER 1 TO 2 INCHES EXPECTED IN THE MORNING. ALSO HAD TO ADJUST TEMPS UP A FEW DEGREES AS MID-HIGH CLOUDS MOVING IN FROM THE WEST HAVE KEPT READINGS FROM FALLING MUCH OVER THE WI BDR COUNTIES. WENT WITH LOWS CLOSER TO ZERO OVER MUCH OF THE INTERIOR FCST AREA AND 5 TO 10 DEGREES ALONG THE LAKE SUPERIOR SHORELINE. $$ .SHORT TERM (TONIGHT AND SUNDAY)... H5 HEIGHTS INDICATE A RIDGE OVR WESTERN NORTH AMERICA WITH TROUGHING OVR EASTERN CANADA INTO THE GREAT LAKES AND NORTHEAST UNITED STATES. POLAR VORTEX HAS SUNK INTO NORTHERN ONTARIO WITH H5 HEIGHTS BLO 500 DAM. COUPLE OF SHORTWAVES WEST OF THE GREAT LAKES TODAY WILL SWING TOWARD THE AREA OR JUST TO THE SOUTH INTO SUNDAY. ISENTROPIC LIFT ON THE 280K SFC WILL PROVIDE A GOOD SWATH OF MID CLOUDS INTO SUN...BUT SYNOPTIC PCPN SHOULD REMAIN FARTHER S OVR WI WHERE LOWER LEVEL MOISTENING IS A BIT MORE PRONOUNCED. AS HAS BEEN THE CASE FOR THE LAST WEEK...ANY PCPN OVR UPR MI WILL BE CAUSED BY LK SUPERIOR. LES RIGHT NOW IS PRETTY MUCH NON EXISTENT. INVERSION LOWERING BLO H9 AS SEEN ON 12Z KINL SOUNDING/EARLY AFTN TAMDAR FM CYQT IS CAUSING THIS TREND. TEMPS AT TOP OF INVERSION CONTINUE TO WARM ALSO... NEARING -15C BY 00Z. LOBES OF LARGE SCALE LIFT FM POLAR VORTEX DROPPING TOWARD LK SUPERIOR LATE TONIGHT/APPROACHING SHORTWAVE FM THE WEST SHOULD BOOST LES AFT MIDNIGHT. LOWER LEVEL WINDS ALSO BECOME LESS SHEARED FM THE WEST AND CONVERGENCE PICKS UP FM SFC-H9 AS WELL. SO...EXPECT LES TO GET SOMEWHAT BETTER ORGANIZED IN THE OVERNIGHT. LOCAL HIGHER RESOLUTION WRF-ARW AND RUC13 INDICATE GREATEST CONVERGENCE OVR KEWEENAW 09Z-18Z SUN AS NW WINDS OVR LK SUPERIOR MEET THE STUBBORN W/SW FLOW OVR LAND. EVEN WITH THESE POSITIVES...INVERSION HEIGHTS STILL ONLY TOP OUT AROUND H85...SO CONVECTIVE DEPTH DOES NOT LOOK TOO IMPRESSIVE. THIS WAS PRIMARY REASON NOT TO GO WITH WARNING. INSTEAD...WILL ISSUE A LES/BLSN ADVY FOR KEWEENAW PENINSULA. ADDED BLSN AS EXPECT BLYR WINDS TO BE BTWN 20-30 MPH LATER TONIGHT THROUGH SUN. WINDS SHIFTING NW IN MIXED LAYER AFT 18Z SHOULD DIMINISH LES ON KEWEENAW SUN AFTN...SO WILL END ADVY AT THAT TIME. OTHER CONCERN IS OVR FAR NE CWA...WHERE AN ADVY MAY BE NEEDED ON SUN. NOT ISSUING THAT NOW SINCE IT IS STILL LATER IN THE SECOND PERIOD. BACK TO WINDS...MODELS HAVE STRUGGLED LATELY WITH WIND SPEEDS OVR LK SUPERIOR. LAST TWO GALE EVENTS...NAM/GFS HAVE UNDERESTIMATED MAX WINDS BY 5-10KT AND IT IS HAPPENING AGAIN TODAY...WITH GALE FORCE GUSTS OBSERVED MOST DAY ON LK SUPERIOR AND 30 KT AT MOST IN MODEL GUIDANCE. SINCE WINDS ARE PROGGED TO INCREASE THROUGH H85 TONIGHT AHEAD OF SHORTWAVES...WENT WITH GALE WARNING ON LK SUPERIOR THROUGH SUN AM. MOS TEMPS FOR TONIGHT/SUNDAY SEEMED REASONABLE. LOWERED TEMPS OVR INLAND WEST HALF (5 TO 10 BLO ZERO) AS CLEAR SKIES THIS EVENING AND FAIRLY LGT WINDS MAY RESULT IN TEMPS DROPPING QUICKLY TOWARD CURRENT DEWPOINTS. .LONG TERM (SUN NIGHT THROUGH SAT)... COLD FRONT REACHING THE KEWEENAW SUN AFTN WILL EXIT THE FCST AREA SUN EVENING. IN ITS WAKE...850MB TEMPS DROP INTO THE -20 TO -24C RANGE OVER LAKE SUPERIOR BY 12Z MON. ALTHOUGH THERE IS PLENTY OF INSTABILITY FOR LES....NAM HAS COME AROUND TO THE GFS WITH RESPECT TO LOWER INVERSIONS OF 4-5KFT AND A LESS SUPPORTIVE MOISTURE PROFILE. SO...AFTER INTIAL BURST OF SNOW WITH FROPA...LES SHOULD SETTLE DOWN TO A RELATIVELY LIGHT INTENSITY THROUGH SUN NIGHT. VEERING WINDS WITH HIGH PRES BUILDING E THRU MANITOBA/ONTARIO WILL ALSO KEEP BANDS SHIFTING...KEEPING ACCUMULATIONS DOWN. IN ADDITION...LARGE SCALE ANTICYCLONIC FLOW WILL BE ANOTHER NEGATIVE. HOWEVER...THERE ARE INDICATIONS THAT LOCAL CONVERGENCE OR EVEN A MESOLOW WILL DEVELOP OVER SCNTRL LAKE SUPERIOR AS VEERING LARGE SCALE WINDS ARE ENHANCED BY LAND BREEZE OFF ONTARIO TO TAKE ON A MORE ERLY COMPONENT OVER ERN SUPERIOR. WILL NEED TO KEEP AN EYE ON THIS POTENTIAL WHICH COULD LEAD TO LOCAL HVY LES IN MARQUETTE OR ALGER COUNTIES LATE SUN NIGHT. ON MON...WINDS CONTINUING VEERING TO A NE DIRECTION...BUT THERE IS LITTLE CHANGE WITH RESPECT TO INVERSION HEIGHTS/MOISTURE PROFILES. SO...LES WILL REMAIN ON THE LIGHT SIDE (SUB ADVY ACCUMULATIONS). IF A MESOLOW DOES DEVELOP OVER SCNTRL LAKE SUPERIOR LATE SUN NIGHT... SNOW COULD BE LOCALLY HVY THRU MON MORNING OVER A SMALL PART OF NCNTL UPPER MI. ALTHOUGH CORE OF COLDEST AIR PASSES JUST NE OF FCST AREA...TEMPS WILL PROBABLY STRUGGLE TO REACH 10F OVER THE HIGHER TERRAIN OF THE W AND NCNTL FCST AREA WITH 850MB TEMPS HOVERING AROUND -22C. TUE THRU SAT...OTHER THAN LES...THERE WON`T BE MUCH PCPN DURING THIS PERIOD UNDER A GENERAL DRY NW FLOW PATTERN. MAIN FCST ISSUE IS POTENTIAL OF A MIDLEVEL LOW TO DROP INTO THE UPPER GREAT LAKES MIDWEEK. 00Z/12Z FEB9 ECWMF/GFS/GLOBAL CANADIAN RUNS WERE IN GOOD AGREEMENT ON SUCH A SCENARIO. THE 00Z/12Z FEB10 ECMWF RUNS STILL SHOW THIS SOLUTION (JUST SLIGHTLY W AND SLIGHTLY DEEPER THAN FEB9 RUNS). THE 00Z/06Z/12Z GFS RUNS HAVE BACKED AWAY FROM THE MIDLEVEL LOW OVER THE UPPER LAKES AND NOW ONLY SHOW AN OPEN WAVE SWINGING THRU THE UPPER LAKES WED OR KEEP MIDLEVEL LOW N OF LAKE SUPERIOR. THE 00Z GLOBAL CANADIAN SUPPORTS THE ECWMF...BUT WITH HEIGHTS NOT NEARLY AS LOW AS THE ECMWF (500MB HEIGHT WITH MIDLEVEL LOW OVER NE LWR MI 00Z THU IN THE CANADIAN SOLUTION IS 180M HIGHER THAN THE ECWMF). THE 00Z UKMET WHICH HAS SHOWN VERY POOR RUN-TO-RUN CONSISTENCY DOES SUPPORT AN ECMWF/CANADIAN SOLUTION BUT IS ABOUT 24HR SLOWER WITH THE WHOLE PROGRESSION OF MIDLEVEL LOW. 12Z UKMET NOW LOOKS JUST LIKE THE ECWMF WITH TIMING AND DEPTH OF MIDLEVEL SYSTEM. 12Z CANADIAN HAS TRENDED DEEPER AND FARTHER W WITH MIDLEVEL LOW AND JUST DRIFTS IT ACROSS THE WRN GREAT LAKES WED AND THU. AT THIS POINT...DIFFERENCES IN THE DETAILS FOR A SYSTEM 3-5DAYS OUT YET WON`T MAKE TOO MUCH DIFFERENCE IN THE BASIC WEATHER HERE AS ALL SUGGEST A GENERAL NRLY FLOW LES PATTERN TUE/WED WITH LIKELY POPS NEAR LAKE SUPERIOR. IF THE ECMWF SOLUTION WORKS OUT...THERE WOULD BE A SIGNIFICANT LAKE EFFECT/LAKE ENHANCED SNOW EVENT FOR AREAS FAVORED BY NRLY LOW-LEVEL WINDS LATE TUE THRU WED NIGHT. ALTHOUGH NON GFS SOLUTIONS SUPPORT POTENTIAL FOR SIGNIFICANT SNOW... CONFIDENCE IS NOT HIGH ENOUGH RIGHT NOW TO START HIGHLIGHTING POSSIBILITY IN HAZARDOUS WX OUTLOOK. LES WILL WIND DOWN WITH MODERATING AIRMASS AND BACKING WINDS THU AND SHOULD ACTUALLY END FRI AS 850MB TEMPS CONTINUE TO RISE. DESPITE REASONABLE GFS/ECMWF AGREEMENT LATE IN THE WEEK...HAVE LOW CONFIDENCE ON TIMING NEXT SHORTWAVE APPROACHING UPPER LAKES LATE FRI. HAVE INCLUDED LOW CHC POPS FOR -SN FRI NIGHT INTO SAT FOR THIS SYSTEM. TEMPS WILL BE BELOW NORMAL EARLY IN THE PERIOD AND WILL RISE TO AROUND NORMAL BY THE END OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING LAKE SUPERIOR. HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. && $$ VOSS (UPDATE) JLA (SHORT TERM) ROLFSON (LONG TERM) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 947 PM EST SAT FEB 10 2007 .UPDATE...A RELATIVELY BENIGN NIGHT ACROSS NRN MICHIGAN COMPARED TO NIGHTS RECENT NIGHTS WITH HIGH PRESSURE MOVING THROUGH TO THE SOUTH...WEDGE OF LOW LEVEL DRY AIR SPREADING IN FROM THE WEST (PER 00Z GRB SOUNDING) AND MODERATING LOW LEVEL TEMPS KEEPING LAKE CONVECTION IN CHECK. 00Z APX SOUNDING SHOWING THE RESULTS WITH THE INVERSION LOWERED BLO 875 MB AND DRYING OUT IN THE LOWER LEVELS. LOW LEVEL FLOW HAS BACKED CONSIDERABLY OVER THE LAST FEW HOURS AS REMAINING LIGHT LAKE EFFECT SNOW SHOWERS/FLURRIES TAKING ON A NEARLY SW FLOW ORIENTATION WHILE AREAS FURTHER INLAND LOOKING AT GENERALLY CLEAR SKIES AT THE MOMENT. UPSTREAM...SATELLITE IMAGERY SHOWING AN AREA OF MID/HIGH CLOUD COVER SLIDING OUT OF WISCONSIN AND HEADING TOWARD LOWER MICHIGAN. MEANWHILE...WATER VAPOR IMAGERY SHOWING NEXT UPSTREAM SHORT WAVE DROPPING QUICKLY SE ACROSS LAKE WINNIPEG... EXPECTED TO BRING ADDITIONAL SNOWFALL TO THE REGION ON SUNDAY. OVERNIGHT...ONLY MINOR TWEAKS ANTICIPATED TO THE GOING FORECAST. LOW LEVEL FLOW EXPECTED TO VEER AROUND MORE WSW-W OVERNIGHT PER 00Z NAM AND RECENT RUC DATA. ENOUGH OVER LAKE INSTABILITY REMAINING BELOW THE INVERSION TO KEEP LIGHT LAKE EFFECT SNOW SHOWERS/FLURRIES GOING PRIMARILY BETWEEN M-72 TO THE STRAITS IN NW LOWER MICHIGAN. BUT WITH INVERSION HEIGHTS ALSO EXPECTED TO REMAIN AOB 875 MB/MARGINAL INSTABILITY (DELTA T`S IN THE MID TEENS) AND FURTHER LOW LEVEL DRYING SLIDING OUT OF WISCONSIN...LOOKING AT ONLY MINOR ACCUMS. PERHAPS AROUND HALF AN INCH OFF THE LONGEST FETCH OF LAKE MICHIGAN IN CHARLEVOIX/EMMET AND CHEBOYGAN COUNTIES. FOR EVERYONE ELSE...AREA OF MID/HIGH CLOUD COVER WILL BE ADVANCING INTO THE REGION OVER THE NEXT FEW HOURS BRINGING SCT-BKN CONDITIONS FOR MOST AREAS. COMBINED WITH A PERSISTENT WIND THIS SHOULD KEEP TEMPS FROM DROPPING TOO FAR. ADAM && .PREV DISCUSSION...ISSUED AT 322 PM EST SAT FEB 10 2007 DISCUSSION...ON THE LATEST SURFACE WEATHER MAP...1031 MB HIGH PRESSURE WAS OVER THE FAR EASTERN PLAINS WITH 1006 MB LOW PRESSURE OVER NORTHEAST ONTARIO. APX RADAR SHOWED LAKE EFFECT OFF OF LAKE MICHIGAN HAD A GENERAL WEAKENING TREND WHILE BEGINNING TO BACK TOWARD THE WEST. THE MAIN SHORT TERM FORECAST CONCERNS WILL REVOLVE AROUND POPS TONIGHT INTO SUNDAY MORNING THEN POPS AND SNOWFALL ACCUMULATIONS FROM SUNDAY AFTERNOON INTO MONDAY. TONIGHT...MEAN SURFACE-850 MB FLOW CONTINUES TO BACK INTO THE WEST OR EVEN WEST SOUTHWEST THIS EVENING AND HOLDS OVERNIGHT. MOISTURE IS DEFINITELY ON THE LEAN SIDE HOWEVER WITH MEAN 900-700 MB RH ONLY 30 TO 40 PERCENT. PLUS 850 MB TEMPERATURES ARE ONLY -13 TO -14C AND INVERSION HEIGHTS ARE A PALTRY 2500 FEET OR SO. THEREFORE...ONLY SCATTERED LIGHT SNOW SHOWERS EXPECTED WITH ACCUMULATIONS UNDER A HALF INCH. OUTSIDE OF LAKE EFFECT AREAS...PARTLY CLOUDY SKIES EXPECTED. A WESTERLY WIND AROUND 10 MPH SHOULD KEEP TEMPERATURES FROM FALLING BELOW ZERO WITH LOWS IN THE SINGLE DIGITS ACROSS MOST AREAS EXCEPT FOR AROUND 10 ABOVE NEAR THE LAKE MICHIGAN SHORELINE. SUNDAY...SURFACE LOW PRESSURE AND DEEP UPPER TROUGH MOVE ACROSS SOUTHEAST ONTARIO DURING THE DAY. ASSOCIATED Q-VECTOR FORCING AND A SURFACE COLD FRONT WILL ARRIVE ACROSS EASTERN UPPER LATE IN THE DAY AND THE FRONT WILL SHIFT WINDS INTO THE WEST NORTHWEST. IN ADDITION...MOISTURE AHEAD OF THIS FEATURE INCREASES IN THE AFTERNOON WITH MEAN 900-700 MB RH TO NEAR 90 PERCENT ACROSS NORTHERN LOWER AND 60 TO 70 PERCENT IN EASTERN UPPER. ENHANCEMENT OFF OF LAKE MICHIGAN EXPECTED WITH 850 MB TEMPERATURES BETWEEN -13 AND -15C. THIS WILL OCCUR ESPECIALLY NEAR THE LAKE MICHIGAN SHORELINE WITH HIGH LIKELY POPS IN ORDER (70). WILL PENCIL IN A COUPLE OF INCHES OF ACCUMULATION FOR NOW IN THESE AREAS AS WELL AS IN THE WHITEFISH POINT/PARADISE REGION AS WINDS VEER TO ONSHORE BEHIND SURFACE COLD FRONT WITH UNDER AN INCH ELSEWHERE. HIGHS RANGING FROM THE UPPER TEENS TO MIDDLE 20S. SUNDAY NIGHT...THE COLD FRONT WILL SWEEP SOUTHWARD OVER THE NORTHERN LAKES REGION. THIS FEATURE WILL DROP SOUTH OF THE STRAITS SUNDAY EVENING...BEFORE EXITING SOUTHEAST OF THE LAKES AROUND 12Z MONDAY. SUFFICIENT MOISTURE ALONG THE FRONT (80 PCT BTW 850/300 MB) WILL BE ENOUGH TO MENTION SNOW SHOWERS FOR THE ENTIRE FORECAST AREA. THE HIGHEST AMOUNTS WILL BE NOTED ALONG LAKES MICHIGAN AND HURON SHORELINES DUE TO LAKE EFFECTS. 925 AND 850 MB WINDS WILL BE TURNING THRU 12Z MONDAY. WINDS WILL BE AT 270 AT 00Z MONDAY...SHIFTING TO 360 BY 12Z MONDAY. MODEL SOUNDINGS SHOW INVERSION HEIGHTS AROUND 4500 FEET DURING THE OVERNIGHT PERIOD...ADDING TO SNOWFALL POTENTIAL OVER FAVORED WEST TO NORTH SNOW BELTS. WILL KEEP SNOW ACCUMULATIONS UNDER ADVISORY CRITERIA AT THE MOMENT...AS BOTH THE FRONTAL POSITION AND WINDS WILL BE CHANGING QUICKLY. THE BEST SNOWFALL CHANCES SHOULD BE BETWEEN 00Z MONDAY AND 06Z MONDAY...AS LAKE EFFECTS AND SYNOPTICS COMBINE. WITH 850 TEMPS REMAINING AROUND -16C...WILL KEEP OVERNIGHT LOWS IN THE SINGLE DIGITS...WILL NOT DROP TEMPS BELOW ZERO AS SNOWFALL AND CLOUD COVER SHOULD HINDER DRASTIC TEMPERATURE DROPS. MONDAY...THE SURFACE TROUGH PUSHES EAST FROM THE LAKES...WITH COLD SURFACE RIDGING BUILDING IN FROM CENTRAL CANADA. 850 MB TEMPS DROP FROM AROUND -16C TO AROUND -20C...WITH MUCH DRIER AIR SINKING SOUTH. 850/300 MB RH DROPS FROM THE 80 PCT SUNDAY NIGHT TO AROUND 40 PERCENT MONDAY MORNING. 925 AND 850 MB WINDS BECOME MORE NORTHERLY BETWEEN 350 AND 010...AS RIDGING SLIDES SOUTH. MODEL SOUNDINGS SHOW INVERSION HEIGHTS OVER NRN LOWER AND EAST UPPER DROPPING TO AROUND 3300 FEET. OVERALL SNOWFALL SHOULD REMAIN LIMITED ONCE AGAIN WITH...THE ABSENCE OF SYNOPTIC FORCING...LOW INVERSION HEIGHTS AND MUCH DRIER AIR (900/700MB RH 40 TO 50 PCT). WILL KEEP MUCH OF NRN LWR MICHIGAN DRY MONDAY...ESPECIALLY IN THE AFTERNOON DUE TO THE MORE NORTHERLY WINDS. WILL HOWEVER KEEP A MENTION OF LAKE INDUCED SNOW SHOWERS RIGHT ALONG THE IMMEDIATE LAKE HURON AND LAKE MICHIGAN SHORELINES. EXPECT AFTERNOON HIGHS TO REMAIN COLD...ONLY IN THE TEENS...AS 850 AIR BEHIND THE FRONTAL PASSAGE DROPS...HOWEVER FULL MID FEB SUNSHINE WILL FEEL PRETTY GOOD. MONDAY NIGHT...MUCH THE SAME EXPECTED MONDAY NIGHT AS MONDAY. LAKE EFFECTS WILL BE THE MAIN FEATURE. 925 AND 850MB WINDS WILL TURN MORE TOWARD THE NORTHEAST...AS THE STRONG COLD AND DRY RIDGE FROM CENTRAL CANADA BUILDS FURTHER SOUTH INTO THE LAKES REGION. MODEL SOUNDINGS ONCE AGAIN SHOW INVERSION HEIGHTS REMAINING AROUND 3000 FEET...AND 900/700 MB RH REMAINS AROUND 40 PERCENT. THEREFORE WILL KEEP SOME MENTION OF LAKE SNOW ALONG THE LAKES MICHIGAN AND HURON IMMEDIATE LAKE SHORES. WILL MENTION MUCH COLDER LOWS MONDAY NIGHT AS COMPARED TO SUNDAY NIGHT...WITH COLDER 850 AIR AND STRONGER SUBSIDENCE GENERATING A CLR SKIES...ESPECIALLY FOR THE INTERIOR PORTIONS OF THE CWA. WILL DROP OVERNIGHT LOWS IN THE LOW SINGLE DIGITS TO AROUND 5 BELOW ZERO. TUESDAY...AGAIN NORTHEAST LAKE EFFECTS THE MAIN ISSUE. 850 MB TEMPS ATTEMPT TO RISE DURING THE AFTERNOON...AS A STRONG STORM SYSTEM PUSHES UP INTO THE NORTHERN OHIO VALLEY. HOWEVER STRONG CANADIAN RIDGE WILL BE FIRMLY IN PLACE ACROSS THE GREAT LAKES...WITH DRY AIR REMAINING. IT WILL BE HARD FOR MUCH CLOUD INCREASE DURING THE DAY AS 900/700 AND 850/300 MB RH REMAINS AROUND 30 TO 40 PERCENT. WILL KEEP SOME LIGHT MENTION OF SNOW SHOWERS OVER THE NORTHEAST PORTIONS OF LOWER MICHIGAN...AS 900/700 WINDS TURN EVEN MORE NORTHEAST TO AROUND 030-040. INVERSIONS HEIGHT REMAIN LOW NEAR 3000 FEET. EXPECT SOME SUN AGAIN TUESDAY...AS SUBSIDENCE AND DRY AIR PREVAIL. WILL GO A FEW DEGREES ABOVE GUIDANCE TUESDAY DUE TO AFTERNOON SOLAR HEATING...HOWEVER HIGHS ONCE AGAIN...HIGHS IN THE TEENS. DAYS 4-7 (WEDNESDAY THROUGH SATURDAY)...A LARGE AREA OF CANADIAN HIGH PRESSURE WILL REMAIN FIRMLY IN PLACE OVER THE LAKES REGION AND CENTRAL US WEDNESDAY AND THURSDAY. A WEAK WAVE DEVELOPS OVER THE UPPER LAKES WEDNESDAY AFTN/EVE...WITH PVA AFFECTING THE REGION IN THE BASE OF A 500 MB TROF...MOVING INTO ERN HUDSON BAY. THIS WILL BE ENOUGH FOR A LEAST A CHC OF SHSN OVER THE CWA INTO THURSDAY. WINDS BECOME FAVORABLE FOR AN EXTENDED PERIOD OF LAKE EFFECT SNOW WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...AS WINDS TURN MORE NORTHWEST...AS THE GREAT LAKES BECOMES A BATTLE ZONE BETWEEN THE STRONG LOW DEVELOPING AND MOVING NORTH ALONG THE ATLANTIC SEABOARD AND THE AREA OF HIGH PRESSURE OVER THE CENTRAL PLAINS. LAKE SNOW BEGINS TO DIMINISH OVER THE REGION FRIDAY AS WINDS BEGIN TURNING WEST...TO ALMOST SOUTHWEST...AS THE NORTH ATLANTIC STORM PUSHES FURTHER NORTH AND THE AREA OF HIGH PRESSURE SWINGS SOUTH INTO THE EASTERN US AND NORTHERN OHIO VALLEY. WARMER TEMPERATURES APPEAR TO BE ON THE HORIZON ACROSS THE GREAT LAKES FOR NEXT WEEKEND. CURRENTLY...850 MB TEMPS ARE PROGGED TO WARM FROM AROUND -20C WEDNESDAY TO -8C ON SATURDAY. SWR && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 436 PM EST SAT FEB 10 2007 .SHORT TERM (TONIGHT AND SUNDAY)... H5 HEIGHTS INDICATE A RIDGE OVR WESTERN NORTH AMERICA WITH TROUGHING OVR EASTERN CANADA INTO THE GREAT LAKES AND NORTHEAST UNITED STATES. POLAR VORTEX HAS SUNK INTO NORTHERN ONTARIO WITH H5 HEIGHTS BLO 500 DAM. COUPLE OF SHORTWAVES WEST OF THE GREAT LAKES TODAY WILL SWING TOWARD THE AREA OR JUST TO THE SOUTH INTO SUNDAY. ISENTROPIC LIFT ON THE 280K SFC WILL PROVIDE A GOOD SWATH OF MID CLOUDS INTO SUN...BUT SYNOPTIC PCPN SHOULD REMAIN FARTHER S OVR WI WHERE LOWER LEVEL MOISTENING IS A BIT MORE PRONOUNCED. AS HAS BEEN THE CASE FOR THE LAST WEEK...ANY PCPN OVR UPR MI WILL BE CAUSED BY LK SUPERIOR. LES RIGHT NOW IS PRETTY MUCH NON EXISTENT. INVERSION LOWERING BLO H9 AS SEEN ON 12Z KINL SOUNDING/EARLY AFTN TAMDAR FM CYQT IS CAUSING THIS TREND. TEMPS AT TOP OF INVERSION CONTINUE TO WARM ALSO... NEARING -15C BY 00Z. LOBES OF LARGE SCALE LIFT FM POLAR VORTEX DROPPING TOWARD LK SUPERIOR LATE TONIGHT/APPROACHING SHORTWAVE FM THE WEST SHOULD BOOST LES AFT MIDNIGHT. LOWER LEVEL WINDS ALSO BECOME LESS SHEARED FM THE WEST AND CONVERGENCE PICKS UP FM SFC-H9 AS WELL. SO...EXPECT LES TO GET SOMEWHAT BETTER ORGANIZED IN THE OVERNIGHT. LOCAL HIGHER RESOLUTION WRF-ARW AND RUC13 INDICATE GREATEST CONVERGENCE OVR KEWEENAW 09Z-18Z SUN AS NW WINDS OVR LK SUPERIOR MEET THE STUBBORN W/SW FLOW OVR LAND. EVEN WITH THESE POSITIVES...INVERSION HEIGHTS STILL ONLY TOP OUT AROUND H85...SO CONVECTIVE DEPTH DOES NOT LOOK TOO IMPRESSIVE. THIS WAS PRIMARY REASON NOT TO GO WITH WARNING. INSTEAD...WILL ISSUE A LES/BLSN ADVY FOR KEWEENAW PENINSULA. ADDED BLSN AS EXPECT BLYR WINDS TO BE BTWN 20-30 MPH LATER TONIGHT THROUGH SUN. WINDS SHIFTING NW IN MIXED LAYER AFT 18Z SHOULD DIMINISH LES ON KEWEENAW SUN AFTN...SO WILL END ADVY AT THAT TIME. OTHER CONCERN IS OVR FAR NE CWA...WHERE AN ADVY MAY BE NEEDED ON SUN. NOT ISSUING THAT NOW SINCE IT IS STILL LATER IN THE SECOND PERIOD. BACK TO WINDS...MODELS HAVE STRUGGLED LATELY WITH WIND SPEEDS OVR LK SUPERIOR. LAST TWO GALE EVENTS...NAM/GFS HAVE UNDERESTIMATED MAX WINDS BY 5-10KT AND IT IS HAPPENING AGAIN TODAY...WITH GALE FORCE GUSTS OBSERVED MOST DAY ON LK SUPERIOR AND 30 KT AT MOST IN MODEL GUIDANCE. SINCE WINDS ARE PROGGED TO INCREASE THROUGH H85 TONIGHT AHEAD OF SHORTWAVES...WENT WITH GALE WARNING ON LK SUPERIOR THROUGH SUN AM. MOS TEMPS FOR TONIGHT/SUNDAY SEEMED REASONABLE. LOWERED TEMPS OVR INLAND WEST HALF (5 TO 10 BLO ZERO) AS CLEAR SKIES THIS EVENING AND FAIRLY LGT WINDS MAY RESULT IN TEMPS DROPPING QUICKLY TOWARD CURRENT DEWPOINTS. .LONG TERM (SUN NIGHT THROUGH SAT)... COLD FRONT REACHING THE KEWEENAW SUN AFTN WILL EXIT THE FCST AREA SUN EVENING. IN ITS WAKE...850MB TEMPS DROP INTO THE -20 TO -24C RANGE OVER LAKE SUPERIOR BY 12Z MON. ALTHOUGH THERE IS PLENTY OF INSTABILITY FOR LES....NAM HAS COME AROUND TO THE GFS WITH RESPECT TO LOWER INVERSIONS OF 4-5KFT AND A LESS SUPPORTIVE MOISTURE PROFILE. SO...AFTER INTIAL BURST OF SNOW WITH FROPA...LES SHOULD SETTLE DOWN TO A RELATIVELY LIGHT INTENSITY THROUGH SUN NIGHT. VEERING WINDS WITH HIGH PRES BUILDING E THRU MANITOBA/ONTARIO WILL ALSO KEEP BANDS SHIFTING...KEEPING ACCUMULATIONS DOWN. IN ADDITION...LARGE SCALE ANTICYCLONIC FLOW WILL BE ANOTHER NEGATIVE. HOWEVER...THERE ARE INDICATIONS THAT LOCAL CONVERGENCE OR EVEN A MESOLOW WILL DEVELOP OVER SCNTRL LAKE SUPERIOR AS VEERING LARGE SCALE WINDS ARE ENHANCED BY LAND BREEZE OFF ONTARIO TO TAKE ON A MORE ERLY COMPONENT OVER ERN SUPERIOR. WILL NEED TO KEEP AN EYE ON THIS POTENTIAL WHICH COULD LEAD TO LOCAL HVY LES IN MARQUETTE OR ALGER COUNTIES LATE SUN NIGHT. ON MON...WINDS CONTINUING VEERING TO A NE DIRECTION...BUT THERE IS LITTLE CHANGE WITH RESPECT TO INVERSION HEIGHTS/MOISTURE PROFILES. SO...LES WILL REMAIN ON THE LIGHT SIDE (SUB ADVY ACCUMULATIONS). IF A MESOLOW DOES DEVELOP OVER SCNTRL LAKE SUPERIOR LATE SUN NIGHT... SNOW COULD BE LOCALLY HVY THRU MON MORNING OVER A SMALL PART OF NCNTL UPPER MI. ALTHOUGH CORE OF COLDEST AIR PASSES JUST NE OF FCST AREA...TEMPS WILL PROBABLY STRUGGLE TO REACH 10F OVER THE HIGHER TERRAIN OF THE W AND NCNTL FCST AREA WITH 850MB TEMPS HOVERING AROUND -22C. TUE THRU SAT...OTHER THAN LES...THERE WON`T BE MUCH PCPN DURING THIS PERIOD UNDER A GENERAL DRY NW FLOW PATTERN. MAIN FCST ISSUE IS POTENTIAL OF A MIDLEVEL LOW TO DROP INTO THE UPPER GREAT LAKES MIDWEEK. 00Z/12Z FEB9 ECWMF/GFS/GLOBAL CANADIAN RUNS WERE IN GOOD AGREEMENT ON SUCH A SCENARIO. THE 00Z/12Z FEB10 ECMWF RUNS STILL SHOW THIS SOLUTION (JUST SLIGHTLY W AND SLIGHTLY DEEPER THAN FEB9 RUNS). THE 00Z/06Z/12Z GFS RUNS HAVE BACKED AWAY FROM THE MIDLEVEL LOW OVER THE UPPER LAKES AND NOW ONLY SHOW AN OPEN WAVE SWINGING THRU THE UPPER LAKES WED OR KEEP MIDLEVEL LOW N OF LAKE SUPERIOR. THE 00Z GLOBAL CANADIAN SUPPORTS THE ECWMF...BUT WITH HEIGHTS NOT NEARLY AS LOW AS THE ECMWF (500MB HEIGHT WITH MIDLEVEL LOW OVER NE LWR MI 00Z THU IN THE CANADIAN SOLUTION IS 180M HIGHER THAN THE ECWMF). THE 00Z UKMET WHICH HAS SHOWN VERY POOR RUN-TO-RUN CONSISTENCY DOES SUPPORT AN ECMWF/CANADIAN SOLUTION BUT IS ABOUT 24HR SLOWER WITH THE WHOLE PROGRESSION OF MIDLEVEL LOW. 12Z UKMET NOW LOOKS JUST LIKE THE ECWMF WITH TIMING AND DEPTH OF MIDLEVEL SYSTEM. 12Z CANADIAN HAS TRENDED DEEPER AND FARTHER W WITH MIDLEVEL LOW AND JUST DRIFTS IT ACROSS THE WRN GREAT LAKES WED AND THU. AT THIS POINT...DIFFERENCES IN THE DETAILS FOR A SYSTEM 3-5DAYS OUT YET WON`T MAKE TOO MUCH DIFFERENCE IN THE BASIC WEATHER HERE AS ALL SUGGEST A GENERAL NRLY FLOW LES PATTERN TUE/WED WITH LIKELY POPS NEAR LAKE SUPERIOR. IF THE ECMWF SOLUTION WORKS OUT...THERE WOULD BE A SIGNIFICANT LAKE EFFECT/LAKE ENHANCED SNOW EVENT FOR AREAS FAVORED BY NRLY LOW-LEVEL WINDS LATE TUE THRU WED NIGHT. ALTHOUGH NON GFS SOLUTIONS SUPPORT POTENTIAL FOR SIGNIFICANT SNOW... CONFIDENCE IS NOT HIGH ENOUGH RIGHT NOW TO START HIGHLIGHTING POSSIBILITY IN HAZARDOUS WX OUTLOOK. LES WILL WIND DOWN WITH MODERATING AIRMASS AND BACKING WINDS THU AND SHOULD ACTUALLY END FRI AS 850MB TEMPS CONTINUE TO RISE. DESPITE REASONABLE GFS/ECMWF AGREEMENT LATE IN THE WEEK...HAVE LOW CONFIDENCE ON TIMING NEXT SHORTWAVE APPROACHING UPPER LAKES LATE FRI. HAVE INCLUDED LOW CHC POPS FOR -SN FRI NIGHT INTO SAT FOR THIS SYSTEM. TEMPS WILL BE BELOW NORMAL EARLY IN THE PERIOD AND WILL RISE TO AROUND NORMAL BY THE END OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW AND BLSN ADVY 06Z UNTIL 18Z SUN MIZ001-003. GALE WARNING LAKE SUPERIOR. HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. && $$ JLA (SHORT TERM) ROLFSON (LONG TERM) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 335 AM EST SAT FEB 10 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW NW ARCTIC BRANCH FLOW ALF OVER THE GRT LKS BTWN PERSISTENT HI AMPLITUDE RDG OVER WRN CAN AND VORTEX CENTERED IN SE CAN. ONE SHRTWV EMBBEDDED WITHIN THIS FLOW HAS TRACKED ACRS NRN WI INTO NRN LWR MI TNGT WHILE ANOTHER HAS DROPPED SE THRU NW ONTARIO TOWARD ANJ. THE TRACK OF THESE SHRTWVS HAS CAUSED LLVL WINDS TO VEER MORE NW THE LAST COUPLE OF HRS...WHICH HAS RESULTED IN LES THAT WAS MAINLY OVER THE KEWEENAW AND OVER THE OPEN WATERS OF ERN LK SUP TO SHIFT INTO ONTONAGON COUNTY AND INTO ALGER/LUCE/NRN SCHOOLCRAFT COUNTIES. MQT 88D SHOWS HIER REFLECTIVITIES IN THE BANDS TO THE E ARE FAIRLY LIMITED...BUT A FEW RETURNS IN THE 24-28DBZ RANGE NOTED WITHIN THE CLOSER BANDS. NW GALE FORCE WINDS OBSVD AT PILM4/STDM4...AND WIND GUSTS ARND 40 MPH NOTED AT P59. LES APPEARS WEAKER OVER THE WRN ZNS WITH SHORTER FETCH (LIMITED BY SOME ICE COVG) AND CLOSER PROXIMITY TO LO INVRNS ARND H9-925 NOTED ON THE 00Z INL/YPL RAOBS AND 03Z TAMDAR SDNG FM CYQT AS WELL AS DRY SUB INVRN LYR (SFC DWPTS UPSTREAM OF WRN LK SUP IN THE -15C TO -20C RANGE). HOWEVER...INL SDNG DOES SHOW SOME MSTR ABV THE INVRN BTWN H925-825. 00Z APX SDNG/TAMDAR SDNG FM CIU HINT THAT INVRN IN AREAS DOWNSTREAM OF LK MODERATION IS H8-85. OVER THE INTERIOR ZNS...SKIES ARE CLR-PCLDY...AND TEMPS HAVE FALLEN AOB 0F AT A NUMBER OF SPOTS. OTRW...SHRTWV RDGING NOTED BLDG INTO SASKATCHEWAN/MANITOBA BEHIND ONTARIO SHRTWV. 00Z YQD SDNG IS QUITE DRY (PWAT 0.06 INCH) AND EXCESSIVELY STABLE (INVRN BASE H95). MAIN FCST CONCERNS THE NEXT COUPLE OF DAYS REVOLVE ARND LES TRENDS/ AMTS/HEADLINES ASSOCIATED WITH SHRTWVS EMBEDDED IN NW ARCTIC BRANCH FLOW AND DROP SE OVER THE GRT LKS. FOR TDAY...SHRTWV RDGING OVER SCNTRL CAN PROGGED TO DRIFT INTO THE UPR GRT LKS. GFS/NAM FCST SDNGS SHOW INVRN BASE AT ERY DROPPING FM H85 THIS MRNG TO H9 BY 00Z SUN WHILE LLVL FLOW BACKS MORE W. INVRN BASE AT CMX FCST TO DROP FM H875 TO H9 (GFS) OR EVEN H925 (NAM) BY THIS EVNG WITH ARPCH OF RDG. ALTHOUGH MOIST H9-85 LYR ON THE INL SDNG MAY SUSTAIN THE LES THRU THE MRNG...SUSPECT ACTIVITY WL REALLY WANE THIS AFTN WITH ARRIVAL OF DRIER AIR W-NW OF INL AND LOWER INVRN BASE. ALTHOUGH RELATIVELY WEAK RADAR RETURNS OVER THE E/SHIFTING NATURE OF LES BANDS SO FAR HAVE PROBABLY LIMITED SN ACCUMULATION THERE...WL EXTEND LES/BLSN ADVY (BLSN PER GALE FORCE WINDS OBSVD OVER LK SUP) THRU THE MRNG FOR ALGER/LUCE ZNS TO ACCOUNT FOR WINDOW OF BETTER MSTR/FVRBL WIND DIRECTION BEFORE INVRN FALLS/FLOW BACKS TOO WSW LATER IN THE AFTN AND DRIER SUB INVRN AIR ARRIVES. DESPITE POTENTIAL FOR FVRBL DENDRITIC SN GROWTH WITH MIXED LYR TEMPS IN THE -12C TO -20C RANGE...STEADILY SHIFTING WINDS/LLVL CNVGC AFT 15Z SHOULD LIMIT THE POTENTIAL FOR WRNG SN AMTS. OVER THE INLAND ZNS...SKIES SHOULD BE PARTLY-MOSUNNY. CONSIDERING THE HI STABILITY OF UPSTREAM AIRMASS/ MAX TEMPS ON FRI/BETTER RECENT VERIFICATION OF THE LO END OF MOS GUIDANCE...WL TEND TOWARD THE LOWER GFS MOS GUIDANCE FOR HI TEMPS TDAY. TNGT...GFS/NAM SHOW ANOTHER SHRTWV DROPPING INTO THE UPR GRT LKS FM SCNTRL CAN. THIS WAVE IS RATHER SHEARED HOWEVER...SO THE FCST IMPACT ON INVRN HGT APPEARS TO BE RATHER MINIMAL. THE GFS SHOWS SOMEWHAT MORE RESPONSE AT CMX WITH INVRN BASE RISING FM H9 TO H875 WITH SOME LO-MID LVL MOISTENING AS WELL. WITH FLOW BACKING TO A MORE 260 DIRECTION...EXPECT LES OVER THE W TO SHIFT TO MAINLY JUST THE KEWEENAW. IN FACT...RECENT RUC13 SHOWS FLOW ENHANCED BY LAND BREEZE BACKING SUFFICIENTLY THAT MODEL QPF IS ALMOST ENTIRELY N OF CMX. IF UPSTREAM AIRMASS WERE MOISTER/SHRTWV STRONGER/INVRN HIER AND ICE OVER THE SRN PORTIONS OF WRN LK SUP WERE ABSENT...POTENTIAL FOR MORE INTENSE DOMINANT BAND IN LAND BREEZE/SYNOPTIC SCALE WNW FLOW CNVGC RUNNING THE LENGTH OF WRN LK SUP TO CAUSE HEAVY SN WOULD BE HI. HOWEVER... NEGATIVES MENTIONED ABV SUG MORE LIKELY SCENARIO WL BE A SUB ADVY EVENT...WITH UP TO 4 INCHES FCST OVER HIER TERRAIN N OF CMX PER RUC13 QPF ARND 0.15 INCH AND FVRBL SN/WATER RATIO. SINCE TEMPS ARND -15C WITHIN MIXED LYR ARE FVRBL FOR DENDRITIC SN GROWTH... REMAIN WARY OF POTENTIAL FOR ADVY SN WITH PERSISTENT LLVL CNVGC. OVER THE E... INCRSG LAND BREEZE WSW FLOW SHOULD PUSH LINGERING LES INTO THE OPEN WATERS OF ERN LK SUP...BUT WL RETAIN CHC POPS NEAR THE SHORE E OF THE PIX ROCKS IN CASE FLOW ABV SHALLOW ARCTIC. SKIES WL BE MARRED BY ONLY SOME HI CLDS ASSOCIATED WITH THE SHRTWV OVER THE INTERIOR...WITH TEMPS NEAR LO END OF MOS GUIDANCE WITH LAND BREEZE/ SHALLOW ARCTIC AIR DESPITE STEADY W WIND/SOME HI CLD. A MORE IMPORTANT SHRTWV/COLD FNT IS FCST TO APRCH ON SUN WITH DPVA/ H85-5 QVECTOR CNVGC IN ADVANCE OF THIS SYS FCST BY GFS/NAM/CNDN MODELS TO RAISE INVRN BASE OVER THE NW AND E TOWARD H8 AND MOISTEN THE LLVLS. CONSIDERING THE POTENTIAL FOR DECENT SN LATER SAT NGT OVER THE KEWEENAW AND APRCH OF THIS SYS/FVRBL TEMPS FOR DENDRITIC SN GROWTH BEFORE ARRIVAL OF COLDER AIR LATE BEHIND THE COLD FROPA... DECIDED TO ISSUE AN LES WATCH FOR THAT AREA SAT NGT INTO SUN BEFORE SHIFTING WINDS TO A MORE UNFVRBL 330 DIRECTION IN THE AFTN DIMINISH THE ACTIVITY THERE. RUC13 SHOWS WSHFT EARLIER IN THE MRNG...BUT NAM/GFS HOLD ON TO FVRBL 270-280 FLOW LONGER UNDER INCRSG DPVA. HAVE TO ADMIT DOUBTS ABOUT ICE COVER/SHORTER FETCH/UPSTREAM DRY AIR MIGHT CUT BACK ON SN AMTS...BUT CONFIDENT ENUF THAT AT LEAST AN ADVY SN WL OCCUR SAT NGT THRU SUN MRNG. SINCE MAIN SN BAND WL BE OFFSHORE OVER THE E WHEN THE SHARPER DYNAMICS ARRIVE...WL HOLD OFF ON ANY ADDITIONAL HEADLINES THERE ATTM. AS LLVL WINDS SHIFT TO MORE NNW SUN NGT...MORE SGNFT LES WL SHIFT MORE TOWARD IWD/MQT. && .MQT WATCHES/WARNINGS/ADVISORIES... HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. LAKE EFFECT SNOW AND BLOWING SNOW ADVY UNTIL 17Z SAT MIZ006-007. LES WATCH 03Z-22Z SUN MIZ001-003. && $$ KC mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE JACKSON MS 845 PM CST SUN FEB 11 2007 .DISCUSSION... MAJOR SOUTHERN STREAM DISTURBANCE HEADED OUR WAY IS EASILY EVIDENT ON CONUS-SCALE WATER VAPOR IMAGERY THIS EVENING. THIS FEATURE WILL BE LARGELY RESPONSIBLE FOR DETERIORATING WEATHER CONDITIONS OVER THE ARKLAMISS OVER THE NEXT 24 HOURS. HOWEVER...THE DISTURBANCE IS CURRENTLY NEAR THE FOUR CORNERS OF THE DESERT SOUTHWEST...SO IT HAS A LONG WAY TO GO AND THEREFORE THE ONSET OF INCLEMENT WEATHER IN THE LOWER MISSISSIPPI VALLEY THROUGH THE DAYLIGHT HOURS ON MONDAY WILL BE GRADUAL. IR IMAGERY SHOWS LOWER CLOUDS FORMED THROUGH WARM AIR AND MOISTURE ADVECTION PROCESSES TO BE THICKEST WEST OF THE MS RIVER THIS EVENING...WITH THOSE CLOUDS MUCH MORE SPORADIC OVER MS. THIS GENERAL TREND SHOULD PERSIST THROUGH THE BULK OF THE NIGHT...ALTHOUGH CLOUDS WILL BE SUBTLY ON THE INCREASE FROM THE WEST TOWARD DAWN. ISENTROPIC LIFT ALOFT MAY BE ENOUGH TO GET SOME LIGHT RAIN TO THE SURFACE BY MIDDAY TO AFTERNOON TOMORROW ALONG AND NORTHWEST OF THE NATCHEZ TRACE CORRIDOR...BUT MODELS CONTINUE TO BACK OFF THE ADVANCE OF CYCLONIC LOW LEVEL FEATURES WITH THE INCOMING SYSTEM SO MOST MEASURABLE PRECIP IN THE REGION SHOULD HOLD OFF UNTIL TOMORROW NIGHT. TEMPERATURES TONIGHT IN THE MENTIONED CLOUD REGIME WILL BE VERY TRICKY SINCE RAD COOLING POTENTIAL WILL BE GOOD IN AREAS OF CLEAR SKIES. TWEAKED FORECAST MINS A BIT TO ACCOUNT FOR CURRENT TRENDS AND THE EXPECTATION THAT TEMPS WILL PROBABLY RISE IN MOST AREAS TOWARDS DAYBREAK AS CLOUDS INCREASE. OVERALL TEMP FORECAST NOT FAR FROM PREVIOUS FORECAST. ADDITIONALLY...REDUCED POPS 5 TO 15 POINTS IN MOST LOCATIONS TOMORROW DUE TO ABOVE REASONING...ALTHOUGH LEAVING NUMBERS IN THE UPPER DELTA ALONE WHERE LIGHT RAIN POTENTIAL STILL DEEMED BEST. /BB/ && .AVIATION... CLOUDS WILL CONTINUE TO GRADUALLY INCREASE FROM THE WEST THROUGH MIDDAY TUESDAY...AT WHICH POINT WIDESPREAD OVERCAST CONDITIONS WILL COMMON. EXPECTING MOST CEILINGS TO REMAIN VFR TONIGHT...BUT THEN DECREASING AT LEAST INTERMITTENT TO MVFR EARLY TUESDAY FROM THE AXIS OF THE MS EASTWARD. MAIN CHANCE OF LIGHT PRECIP COMING IN LATER TOMORROW WILL BE CONFINED NORTHWEST OF THE NATCHEZ TRACE CORRIDOR. /BB/ && .PREVIOUS DISCUSSION...(TONIGHT THROUGH MONDAY NIGHT) LATEST SATELLITE VAPOR IMAGERY SHOWED THE REGION UNDER WESTERLY FLOW ALOFT WITH A SERIES OF SHORT WAVES MOVING THROUGH THE SOUTHERN STREAM. LATEST VISIBLE IMAGERY SHOWED AN AREA OF LOW CLOUDS MOVING ACROSS LOUISIANA AND ARKANSAS INTO WESTERN MISSISSIPPI. LATEST RUC ANALYSIS SHOWS EQUIVALENT POTENTIAL TEMP ADVECTION COMING INTO THE REGION FROM THE WEST. ON THE SURFACE HIGH PRESSURE WAS CENTERED ACROSS THE LOWER MISSISSIPPI VALLEY. LOOKING AT THE SHORT TERM. WE WILL BE DEALING WITH SOME SEVERE WEATHER ON MONDAY NIGHT ACCORDING TO THE MODELS. CLOUDS WILL INCREASE ACROSS THE REGION FROM THE WEST TONIGHT AS SOUTHERLY LOW LEVEL FLOW AND THETA ADVECTION BECOMES ESTABLISHED ACROSS THE REGION. AN UPPER LEVEL DISTURBANCE WILL BE PUSHING INTO THE SOUTHERN PLAINS WITH AN ASSOCIATED AREA OF LOW PRESSURE. FOR MONDAY THINGS START TO GET A LITTLE INTERESTING. WE WILL GET SOME WARM AIR ADVECTION AS A WARM FRONT PUSHES THROUGH THE REGION DURING THE DAY. IT WILL ADVECT SOME 40S AND 50S DEWPOINTS ACROSS THE REGION. WITH THE UPPER DISTURBANCE SOME GOOD 500 DKM HEIGHT FALLS APPROACH THE REGION DURING THE FROM THE PLAINS(70 DKM). IN THE JET DEPARTMENT A STRONG UPPER JET OF AROUND 150 KNOTS PUNCHES INTO THE SOUTHERN PLAINS TOWARD THE REGION...WHICH WILL AFFECT US ON MONDAY NIGHT. INSTABILITY WILL STILL BE LACKING AT THIS POINT. WE WILL HAVE JUST ENOUGH LIFT AND INSTABILITY FOR SOME PATCHY LIGHT RAIN MONDAY MORNING THEN MIX IN SOME ISOLATED THUNDERSTORMS...GENERALLY ALONG AND WEST OF THE MS RIVER ON MONDAY AFTERNOON. THIS SYSTEM WILL HAVE SOME GOOD COOLING ALOFT WITH -16C TO -18C COMING INTO THE REGION LATE MONDAY AFTERNOON. FOR MONDAY NIGHT THINGS COME TOGETHER FOR A ROUND OF SEVERE WEATHER. THE SHORTWAVE COMING THROUGH THE PLAINS BECOME NEGATIVELY TILTED AS THE ASSOCIATED SURFACE LOW PUSHES NORTHEAST ACROSS ARKANSAS DURING THE NIGHT. JET DYNAMICS COME INTO PLAY AS WE WILL GET INTO THE LEFT FRONT QUAD OF A 160 PLUS KNOT JET BY EARLY TUESDAY. WE WILL ALSO GET INTO THE LEFT FRONT QUAD OF 70 KNOT JET AT 500 MB. TEMPS WILL BE QUITE COOL ALOFT WITH -45C AT 300 MB AND 500 MB TEMPS AT -18 TO -21C...WHICH COULD SPELL SOME GOOD HAIL RISKS. THERE WILL BE 100 PLUS DKM HEIGHT FALLS COMING INTO THE REGION BY EARLY TUESDAY...WHICH SPELL GOOD FOLDING OF THE TROP. WITH THIS SCENARIO SHEAR WILL BE STRONG WITH STRONG DIVERGENCE ALOFT IN THE MID TO UPPER LEVELS. DURING THE NIGHT DEWPOINTS WILL CREEP UP TO THE LOWER TO UPPER 50S...WHICH MEANS THE CONVECTION WILL BE ELEVATED. EXPECT THE CONVECTION TO INCREASE IN COVERAGE AS THE LOWER AND UPPER LEVEL DYNAMICS EVOLVE DURING THE NIGHT. AS FAR AS LOW LEVEL INSTABILITY IS CONCERN LIFTED INDEXES -1 TO -5 I-55 ON WESTWARD...SHOWALTER INDEX 0 TO -2...PRECIPITABLE WATER AROUND ONE INCH...CAPE AROUND 500...AND LAPSE RATES 6-8C. TIMING WISE EXPECT THE BEST CHANCE OF SEVERE WEATHER IN THE DELTA REGION FROM THE 8 PM TO 3 AM TIME FRAME...THE NATCHEZ TRACE TO I-55 CORRIDOR TO BE FROM MIDNIGHT TO 4 AM...THEN THE EAST MISSISSIPPI REGION FROM 3 TO 6 AM TUESDAY MORNING. THE AREA MAINLY ALONG AND WEST OF INTERSTATE 55 WILL HAVE THE BETTER CHANCE OF SEVERE WEATHER. THE PRIMARY RISKS FOR THIS SEVERE EVENT WILL PRIMARILY BE HAIL WITH A LESS RISK FOR DAMAGING WINDS. HAIL SIZE WISE LOOKING AT UP TO QUARTER TO GOLF BALL SIZE HAIL DURING THE NIGHT. IF WE DO GET ISOLATED TORNADOES...THE BEST CHANCE LOOKS TO BE IN THE SOUTHWEST IF 60 PLUS DEWPOINTS SNEAK INTO THAT AREA BEFORE DAYBREAK. LOOKING AT SURFACE WINDS AS THE AREA OF LOW PRESSURE MOVES NORTHWEST OF THE REGION THE PRESSURE GRADIENT WILL TIGHTEN ACROSS THE REGION. GUIDANCE HAD GRIDS OF AROUND 20 KNOTS IN THE DELTA REGION...SO PUT IN GUST GRIDS OF APPROACHING 30 KNOTS...WHICH WILL BRING US TO POSSIBLE LAKE WIND ADVISORY CRITERIA FOR MONDAY NIGHT. THE WILL BE ESPECIALLY TRUE ACROSS THE DELTA REGION. AS FAR AS TEMPS ARE CONCERN MADE SOME SLIGHT ADJUSTMENTS TO GUIDANCE. WITH POPS WENT CLOSE TO GUIDANCE ON POPS FOR MONDAY AND MAINTAINED HIGH POPS FOR MONDAY NIGHT. LONG TERM...(TUESDAY THROUGH SUNDAY)SIMILAR TO YESTERDAY...TWO MAIN ELEMENTS OF THE FORECAST TO DISCUSS. FIRST WILL BE THE EXTENDED SVR RISK ON TUE THEN A SHIFT TO COLDER CONDITIONS FOR THE REMAINDER OF THE WEEK. WITH MOST OF THE SVR STORM ACTIVITY OCCURRING BETWEEN MIDNIGHT AND 6 AM...THE START OF THE TUE PERIOD WILL LIKELY BE QUITE. THAT WILL NOT LAST REAL LONG FOR SOME LOCATIONS AS I WILL DISCUSS. BASED ON THE PROGRESSION OF THINGS...I REALLY DON`T EXPECT THE MAIN AXIS OF STORMS TO LINGER PAST 6 AM. JUST TO COVER ANY TIMING ISSUES...I WILL HAVE SOME WX GOING FOR THE FIRST FEW HOURS OF THE TUE PERIOD FOR THE FAR EASTERN CWA. WHAT I AM EXPECTING IS THE PRE FRONTAL TROUGH (AND ASSOCIATED WX) TO SHIFT EAST OF THE CWA BETWEEN 5-7 AM AS THE UPPER TROUGH TAKES ON NEG TILT AND THE DRY SLOT SURGES EAST. THIS DRY SLOT WILL KEEP MOST OF THE CWA QUIET THROUGH LATE MORNING OR AROUND NOON. THE KEY NOW BECOMES THE POSITION AND PROGRESSION OF THE SFC LOW AND COLD FRONT. THE PAST SEVERAL RUNS HAVE SLOWED DOWN THIS PROGRESSION AND THE LATEST ONE IS NO DIFFERENT. THIS HAS HUGE IMPACTS ON THE FORECAST FOR TUE NOW. AS THE DRY SLOT MOVES OVER THE AREA...COLDER TEMPS ALOFT (-20C AT H5) WILL SERVE TO STEEPEN ALREADY STEEP LAPSE RATES! COMBINE THIS WITH SFC TEMPS BETWEEN 65-73 IN ADVANCE OF THE SFC FRONT AND THE REGION WILL BECOME VERY UNSTABLE. THIS UNSTABLE AIR WILL LIKELY GET REALIZED FOR SOME LOCATIONS AS FRONTAL FORCING OCCURS WITH THE SE PUSH OF THE ACTUAL FRONT. THE FRONT WON`T FIRE STORMS EVERYWHERE DUE TO SOME LOCATIONS BEING CAPED AND IN A UNFAVORABLE LOCATION DUE TO THE POSITION OF THE MID AND UPPER LEVEL JET. AT THIS TIME...AREAS ALONG AND NORTH OF A GREENVILLE TO CARTHAGE TO QUITMAN LINE WILL BE LOCATED N OF THE H5 JET STREAK AND WITHIN THE VERY FAVORABLE CYCLONICALLY CURVED SIDE OF THIS JET. AREAS S OF THAT WILL BE UNDER THE JET CORE (NOT FAVORABLE) AND BATTLING LOW-LEVEL CAPPING. THE THING ABOUT THE NORTHERN AREA IS THAT IT WILL BE QUITE UNSTABLE AS THE FRONT AND ITS FORCING MOVE THROUGH...SOMETIME BETWEEN LATE MORNING AND LATE AFTERNOON. AT THIS TIME...1000-1500 MLCAPE AND -5 TO -8 LI LOOK TO BE PRESENT WITH THE MLCAPE OF THE "FAT" VARIETY. WHAT DOES ALL THIS MEAN? THIS POINTS TO A SECONDARY SVR WX RISK FOR LATE TUE MORNING INTO THE AFTERNOON HOURS. AT THIS TIME...AN AREA ALONG AND NORTH OF A GREENVILLE TO CARTHAGE TO QUITMAN LINE SEEM UNDER THE GUN. THIS THERMODYNAMIC SETUP REALLY FAVORS LARGE HAIL...AT LEAST TO GOLF BALL SIZE IF NOT NOT LARGER. I EXPECT SCT SUPERCELL STORMS IN THIS ENVIRONMENT ALONG AN IN ADVANCE OF THE SFC FRONT. DEEP LAYER SHEAR AND THE PRESENCE OF A DRY ATMOSPHERE SUGGEST DISCRETE SUPERCELLS WITH THE RISK OF LARGE HAIL. THINGS SHOULD EVOLVE QUICKLY AND BE DONE WITH OR OUT OF THE CWA BY 21-23Z AS UNFAVORABLE JET LEVEL WINDS WILL MOVE IN BY LATE AFTERNOON. WITH THAT DONE NOW DONE...BUNDLE UP AND GET READY FOR ANOTHER SHOT OF COLD WX. AS THE FRONT PUSH SE AND THROUGH THE CWA...DON`T BE SURPRISED TO SEE LIGHT RA...SPRINKLES OR EVEN DRIZZLE AS THE LOW-LEVELS GET SQUEEZED. CLOUDS HANG AROUND THROUGH AT LEAST EARLY TUE AS CAA REMAINS STRONG. AS FOR TEMPS...I FOLLOWED CLOSE TO GUID TEMPS ON TUE AND ACTUALLY BUMPED A FEW SITES UP A TAD BASED ON FORECAST SOUNDINGS. AREAS ALONG AND SE OF THE TRACE WILL LIKELY SEE 66-73 DEGREES TUE AFTERNOON. THINGS TURN COLD TUE NIGHT AND WILL FOLLOW LATEST GUID WITH AROUND 30 N TO NEAR 40 SOUTH. AS FOR THE REST OF THE FORECAST...CURRENT LOW TEMPS WERE GOOD AND STAYED BASICALLY WITH WHAT WE HAD WITH FEW TWEAKS. THE MAIN CHANGES WERE TO GO COLDER WITH HIGHS WED/THU. I STAYED CONSERVATIVE AND WENT WITH UPPER 30S N TO LOWER/MID 40S SOUTH. I COULD ACTUALLY KNOCK OFF 3-5 MORE DEGREES. && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ 50 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 240 PM CST SUN FEB 11 2007 .DISCUSSION...(TONIGHT THROUGH MONDAY NIGHT) LATEST SATELLITE VAPOR IMAGERY SHOWED THE REGION UNDER WESTERLY FLOW ALOFT WITH A SERIES OF SHORT WAVES MOVING THROUGH THE SOUTHERN STREAM. LATEST VISIBLE IMAGERY SHOWED AN AREA OF LOW CLOUDS MOVING ACROSS LOUISIANA AND ARKANSAS INTO WESTERN MISSISSIPPI. LATEST RUC ANALYSIS SHOWS EQUIVALENT POTENTIAL TEMP ADVECTION COMING INTO THE REGION FROM THE WEST. ON THE SURFACE HIGH PRESSURE WAS CENTERED ACROSS THE LOWER MISSISSIPPI VALLEY. LOOKING AT THE SHORT TERM. WE WILL BE DEALING WITH SOME SEVERE WEATHER ON MONDAY NIGHT ACCORDING TO THE MODELS. CLOUDS WILL INCREASE ACROSS THE REGION FROM THE WEST TONIGHT AS SOUTHERLY LOW LEVEL FLOW AND THETA ADVECTION BECOMES ESTABLISHED ACROSS THE REGION. AN UPPER LEVEL DISTURBANCE WILL BE PUSHING INTO THE SOUTHERN PLAINS WITH AN ASSOCIATED AREA OF LOW PRESSURE. FOR MONDAY THINGS START TO GET A LITTLE INTERESTING. WE WILL GET SOME WARM AIR ADVECTION AS A WARM FRONT PUSHES THROUGH THE REGION DURING THE DAY. IT WILL ADVECT SOME 40S AND 50S DEWPOINTS ACROSS THE REGION. WITH THE UPPER DISTURBANCE SOME GOOD 500 DKM HEIGHT FALLS APPROACH THE REGION DURING THE FROM THE PLAINS(70 DKM). IN THE JET DEPARTMENT A STRONG UPPER JET OF AROUND 150 KNOTS PUNCHES INTO THE SOUTHERN PLAINS TOWARD THE REGION...WHICH WILL AFFECT US ON MONDAY NIGHT. INSTABILITY WILL STILL BE LACKING AT THIS POINT. WE WILL HAVE JUST ENOUGH LIFT AND INSTABILITY FOR SOME PATCHY LIGHT RAIN MONDAY MORNING THEN MIX IN SOME ISOLATED THUNDERSTORMS...GENERALLY ALONG AND WEST OF THE MS RIVER ON MONDAY AFTERNOON. THIS SYSTEM WILL HAVE SOME GOOD COOLING ALOFT WITH -16C TO -18C COMING INTO THE REGION LATE MONDAY AFTERNOON. FOR MONDAY NIGHT THINGS COME TOGETHER FOR A ROUND OF SEVERE WEATHER. THE SHORTWAVE COMING THROUGH THE PLAINS BECOME NEGATIVELY TILTED AS THE ASSOCIATED SURFACE LOW PUSHES NORTHEAST ACROSS ARKANSAS DURING THE NIGHT. JET DYNAMICS COME INTO PLAY AS WE WILL GET INTO THE LEFT FRONT QUAD OF A 160 PLUS KNOT JET BY EARLY TUESDAY. WE WILL ALSO GET INTO THE LEFT FRONT QUAD OF 70 KNOT JET AT 500 MB. TEMPS WILL BE QUITE COOL ALOFT WITH -45C AT 300 MB AND 500 MB TEMPS AT -18 TO -21C...WHICH COULD SPELL SOME GOOD HAIL RISKS. THERE WILL BE 100 PLUS DKM HEIGHT FALLS COMING INTO THE REGION BY EARLY TUESDAY...WHICH SPELL GOOD FOLDING OF THE TROP. WITH THIS SCENARIO SHEAR WILL BE STRONG WITH STRONG DIVERGENCE ALOFT IN THE MID TO UPPER LEVELS. DURING THE NIGHT DEWPOINTS WILL CREEP UP TO THE LOWER TO UPPER 50S...WHICH MEANS THE CONVECTION WILL BE ELEVATED. EXPECT THE CONVECTION TO INCREASE IN COVERAGE AS THE LOWER AND UPPER LEVEL DYNAMICS EVOLVE DURING THE NIGHT. AS FAR AS LOW LEVEL INSTABILITY IS CONCERN LIFTED INDEXES -1 TO -5 I-55 ON WESTWARD...SHOWALTER INDEX 0 TO -2...PRECIPITABLE WATER AROUND ONE INCH...CAPE AROUND 500...AND LAPSE RATES 6-8C. TIMING WISE EXPECT THE BEST CHANCE OF SEVERE WEATHER IN THE DELTA REGION FROM THE 8 PM TO 3 AM TIME FRAME...THE NATCHEZ TRACE TO I-55 CORRIDOR TO BE FROM MIDNIGHT TO 4 AM...THEN THE EAST MISSISSIPPI REGION FROM 3 TO 6 AM TUESDAY MORNING. THE AREA MAINLY ALONG AND WEST OF INTERSTATE 55 WILL HAVE THE BETTER CHANCE OF SEVERE WEATHER. THE PRIMARY RISKS FOR THIS SEVERE EVENT WILL PRIMARILY BE HAIL WITH A LESS RISK FOR DAMAGING WINDS. HAIL SIZE WISE LOOKING AT UP TO QUARTER TO GOLF BALL SIZE HAIL DURING THE NIGHT. IF WE DO GET ISOLATED TORNADOES...THE BEST CHANCE LOOKS TO BE IN THE SOUTHWEST IF 60 PLUS DEWPOINTS SNEAK INTO THAT AREA BEFORE DAYBREAK. LOOKING AT SURFACE WINDS AS THE AREA OF LOW PRESSURE MOVES NORTHWEST OF THE REGION THE PRESSURE GRADIENT WILL TIGHTEN ACROSS THE REGION. GUIDANCE HAD GRIDS OF AROUND 20 KNOTS IN THE DELTA REGION...SO PUT IN GUST GRIDS OF APPROACHING 30 KNOTS...WHICH WILL BRING US TO POSSIBLE LAKE WIND ADVISORY CRITERIA FOR MONDAY NIGHT. THE WILL BE ESPECIALLY TRUE ACROSS THE DELTA REGION. AS FAR AS TEMPS ARE CONCERN MADE SOME SLIGHT ADJUSTMENTS TO GUIDANCE. WITH POPS WENT CLOSE TO GUIDANCE ON POPS FOR MONDAY AND MAINTAINED HIGH POPS FOR MONDAY NIGHT. LONG TERM...(TUESDAY THROUGH SUNDAY)SIMILAR TO YESTERDAY...TWO MAIN ELEMENTS OF THE FORECAST TO DISCUSS. FIRST WILL BE THE EXTENDED SVR RISK ON TUE THEN A SHIFT TO COLDER CONDITIONS FOR THE REMAINDER OF THE WEEK. WITH MOST OF THE SVR STORM ACTIVITY OCCURRING BETWEEN MIDNIGHT AND 6 AM...THE START OF THE TUE PERIOD WILL LIKELY BE QUITE. THAT WILL NOT LAST REAL LONG FOR SOME LOCATIONS AS I WILL DISCUSS. BASED ON THE PROGRESSION OF THINGS...I REALLY DON`T EXPECT THE MAIN AXIS OF STORMS TO LINGER PAST 6 AM. JUST TO COVER ANY TIMING ISSUES...I WILL HAVE SOME WX GOING FOR THE FIRST FEW HOURS OF THE TUE PERIOD FOR THE FAR EASTERN CWA. WHAT I AM EXPECTING IS THE PRE FRONTAL TROUGH (AND ASSOCIATED WX) TO SHIFT EAST OF THE CWA BETWEEN 5-7 AM AS THE UPPER TROUGH TAKES ON NEG TILT AND THE DRY SLOT SURGES EAST. THIS DRY SLOT WILL KEEP MOST OF THE CWA QUIET THROUGH LATE MORNING OR AROUND NOON. THE KEY NOW BECOMES THE POSITION AND PROGRESSION OF THE SFC LOW AND COLD FRONT. THE PAST SEVERAL RUNS HAVE SLOWED DOWN THIS PROGRESSION AND THE LATEST ONE IS NO DIFFERENT. THIS HAS HUGE IMPACTS ON THE FORECAST FOR TUE NOW. AS THE DRY SLOT MOVES OVER THE AREA...COLDER TEMPS ALOFT (-20C AT H5) WILL SERVE TO STEEPEN ALREADY STEEP LAPSE RATES! COMBINE THIS WITH SFC TEMPS BETWEEN 65-73 IN ADVANCE OF THE SFC FRONT AND THE REGION WILL BECOME VERY UNSTABLE. THIS UNSTABLE AIR WILL LIKELY GET REALIZED FOR SOME LOCATIONS AS FRONTAL FORCING OCCURS WITH THE SE PUSH OF THE ACTUAL FRONT. THE FRONT WON`T FIRE STORMS EVERYWHERE DUE TO SOME LOCATIONS BEING CAPED AND IN A UNFAVORABLE LOCATION DUE TO THE POSITION OF THE MID AND UPPER LEVEL JET. AT THIS TIME...AREAS ALONG AND NORTH OF A GREENVILLE TO CARTHAGE TO QUITMAN LINE WILL BE LOCATED N OF THE H5 JET STREAK AND WITHIN THE VERY FAVORABLE CYCLONICALLY CURVED SIDE OF THIS JET. AREAS S OF THAT WILL BE UNDER THE JET CORE (NOT FAVORABLE) AND BATTLING LOW-LEVEL CAPPING. THE THING ABOUT THE NORTHERN AREA IS THAT IT WILL BE QUITE UNSTABLE AS THE FRONT AND ITS FORCING MOVE THROUGH...SOMETIME BETWEEN LATE MORNING AND LATE AFTERNOON. AT THIS TIME...1000-1500 MLCAPE AND -5 TO -8 LI LOOK TO BE PRESENT WITH THE MLCAPE OF THE "FAT" VARIETY. WHAT DOES ALL THIS MEAN? THIS POINTS TO A SECONDARY SVR WX RISK FOR LATE TUE MORNING INTO THE AFTERNOON HOURS. AT THIS TIME...AN AREA ALONG AND NORTH OF A GREENVILLE TO CARTHAGE TO QUITMAN LINE SEEM UNDER THE GUN. THIS THERMODYNAMIC SETUP REALLY FAVORS LARGE HAIL...AT LEAST TO GOLF BALL SIZE IF NOT NOT LARGER. I EXPECT SCT SUPERCELL STORMS IN THIS ENVIRONMENT ALONG AN IN ADVANCE OF THE SFC FRONT. DEEP LAYER SHEAR AND THE PRESENCE OF A DRY ATMOSPHERE SUGGEST DISCRETE SUPERCELLS WITH THE RISK OF LARGE HAIL. THINGS SHOULD EVOLVE QUICKLY AND BE DONE WITH OR OUT OF THE CWA BY 21-23Z AS UNFAVORABLE JET LEVEL WINDS WILL MOVE IN BY LATE AFTERNOON. WITH THAT DONE NOW DONE...BUNDLE UP AND GET READY FOR ANOTHER SHOT OF COLD WX. AS THE FRONT PUSH SE AND THROUGH THE CWA...DON`T BE SURPRISED TO SEE LIGHT RA...SPRINKLES OR EVEN DRIZZLE AS THE LOW-LEVELS GET SQUEEZED. CLOUDS HANG AROUND THROUGH AT LEAST EARLY TUE AS CAA REMAINS STRONG. AS FOR TEMPS...I FOLLOWED CLOSE TO GUID TEMPS ON TUE AND ACTUALLY BUMPED A FEW SITES UP A TAD BASED ON FORECAST SOUNDINGS. AREAS ALONG AND SE OF THE TRACE WILL LIKELY SEE 66-73 DEGREES TUE AFTERNOON. THINGS TURN COLD TUE NIGHT AND WILL FOLLOW LATEST GUID WITH AROUND 30 N TO NEAR 40 SOUTH. AS FOR THE REST OF THE FORECAST...CURRENT LOW TEMPS WERE GOOD AND STAYED BASICALLY WITH WHAT WE HAD WITH FEW TWEAKS. THE MAIN CHANGES WERE TO GO COLDER WITH HIGHS WED/THU. I STAYED CONSERVATIVE AND WENT WITH UPPER 30S N TO LOWER/MID 40S SOUTH. I COULD ACTUALLY KNOCK OFF 3-5 MORE DEGREES && .PRELIMINARY POINT TEMPS/POPS... JACKSON 39 64 54 66 / 8 26 97 44 MERIDIAN 35 64 50 70 / 5 14 90 71 VICKSBURG 42 63 55 62 / 9 38 100 23 HATTIESBURG 38 66 53 73 / 6 8 74 30 NATCHEZ 44 65 56 65 / 11 35 99 12 GREENVILLE 40 60 52 58 / 12 54 100 54 GREENWOOD 38 61 54 60 / 9 40 100 67 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM/AVIATION: 17 LONG TERM: CME ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 515 PM CST SUN FEB 11 2007 .DISCUSSION... MONDAY THROUGH TUESDAY CONTINUES TO BE THE FOCUS AS A SIGNIFICANT WINTER STORM WILL AFFECT THE REGION. GFS/NAM/SREF ARE IN GOOD AGREEMENT WITH RESPECT TO THE TRACK OF THE SURFACE LOW. DID NOTICE THAT LAST COUPLE OF MODEL RUNS HAVE TAKEN THE SURFACE LOW A TAD FURTHER SOUTH. MODELS ALSO CLOSE ON TIMING/STRENGTH OF MID LEVEL SHORTWAVE THROUGH MONDAY NIGHT...WITH THE GFS A TAD FASTER THAN THE NAM. PRIMARY DIFFERENCES...ALTHOUGH MINOR...ARE WITH RESPECT TO THE MASS FIELDS...AND THEY COULD HAVE SIGNIFICANT EFFECTS ON THE SENSIBLE WEATHER. OVERALL FELT THE GFS/SREF OFFER THE BEST CONTINUITY WITH A DOWNWARD ADJUSTMENT TO THE GFS QPF...AT LEAST INITIALLY. SOUTHERLY BOUNDARY LAYER WINDS HAVE EFFECTIVELY DRAWN UP WARMER MORE MOIST AIR. NOW THAT THE LOW CLOUDS ARE ROLLING IN TEMPERATURES OVER THE WESTERN AND SOUTHERN CWA SHOULD ONLY DRIFT DOWNWARD WHILE AN EARLY EVENING LOW ANTICIPATED IN THE NORTHEASTERN COUNTIES BEFORE REBOUNDING ONCE THE CLOUDS AND MOISTURE MOVE IN THIS EVENING. HAVE ONLY MADE MINOR ADJUSTMENTS TO THE OVERALL GRIDS ON PLACEMENT AND TIMING OF THE DIFFERENT WEATHER TYPES. SLEET NOT AS MUCH OF AN ISSUE BUT FREEZING RAIN AND/OR FREEZING DRIZZLE COULD BECOME A MORE SIGNIFICANT ISSUE. STILL EXPECTING AN EAST-WEST FRONTAL BOUNDARY TO SET UP BY TOMORROW MORNING ACROSS NORTHERN MO. ONCE THE FRONT SETS UP IT SHOULD HOLD STEADY THROUGH THE DAYLIGHT HOURS AND WAIT TILL THE SURFACE LOW TRACKS SOUTH AND EAST OF THE CWA. ONCE THAT OCCURS THE COLDER AIR NECESSARY TO SUFFICIENTLY COOL THE COLUMN FOR A CHANGE OVER TO SNOW WILL SURGE SOUTHWARD. RIGHT NOW THAT LOOKS LIKE IT WILL BEGIN MID TO LATE AFTERNOON OVER THE FAR NORTHERN COUNTIES. UNTIL THEN INSPECTION OF THE MODEL SOUNDINGS INDICATE A LACK OF ICE CRYSTALS ACROSS NORTHERN MO SO FREEZING PRECIPITATION WILL BE THE PRIMARY WEATHER TYPE WHILE AREAS SOUTH OF A KANSAS CITY TO MOBERLY LINE SHOULD SEE ALL RAIN. THAT BEING SAID WILL NEED TO KEEP AN EYE ON MORNING TEMPERATURES AND ANY PRECIPITATION OVER THE EXTREME SOUTHEAST COUNTIES AS THEY WILL BE FURTHEST FROM THE MORE MOIST AIR AND MAY BE COOL ENOUGH AT THE START OF THE MORNING FOR SOME PATCHY LIGHT FREEZING RAIN. TEMPERATURES SHOULD MOVE LITTLE DURING THE DAY. PRIMARY LIFT WILL ARRIVE MONDAY NIGHT AS STRONG ISENTROPIC ASCENT CENTERED ON THE 300K SURFACE AND PRONOUNCED SLOPED FRONTOGENIC FORCING WILL LEAD TO HEAVIER SNOW RATES ACROSS NORTHERN MO. STILL CONCERNED ABOUT THE 3-4 G/KG OF MOISTURE AVAILABLE FOR SNOW PRODUCTION BUT TIME CROSS SECTIONS SHOW THE CENTER OF THE BEST UPWARD VERTICAL MOTION IS NOW CENTERED BELOW THE FAVORED DENDRITIC GROWTH ZONE. IF THIS REGION OF UVV SHIFTS UPWARDS THEN LATER FORECASTS WILL NEED TO CONSIDER INCREASING SNOW AMOUNTS. LATER SHIFTS WILL ALSO NEED TO KEEP AN EYE ON EVOLUTION OF CONVECTION. EXPECT ANY THUNDER ON MONDAY TO OCCUR JUST SOUTH OF THE CWA BUT IF THE MODELS SHIFT THE SYSTEM TO THE NORTH THEN THIS WILL NEED TO BE REVISITED. PVU PROGS ALSO INDICATE POTENTIAL FOR CONVECTIVE SNOWS WITHIN THE DEFORMATION ZONE WHICH FORMS LATE MONDAY NIGHT OVER EASTERN KS. THIS WAS PRIMARY REASON TO EXTEND THE WINTER STORM WATCH THROUGH TUESDAY MORNING AS ACCUMULATING SNOWS WILL LAST THROUGH TUESDAY MORNING. LATER SHIFTS WILL ALSO NEED TO CONSIDER WHETHER OR NOT ENOUGH SNOW WILL FALL UNDER THE DEFORMATION ZONE TO MEET WARNING CRITERIA. STILL A WAYS OUT BUT JUST ANOTHER ITEM TO CONSIDER. MJ WEDNESDAY-SUNDAY... FOR A COUPLE DAYS FOLLOWING THE EARLY WORK WEEK WINTER STORM TEMPERATURES ACROSS THE CENTRAL PLAINS WILL REMAIN WELL BELOW NORMAL. A COLD SURFACE HIGH WILL FLOW SOUTH AS THE WINTER STORM SHORTWAVE EXITS THE PLAINS. TRENDED WEDNESDAY AND THURSDAY TEMPERATURES DOWN AS A RESULT. THURSDAY SHOULD SEE A SLOW BEGINNING TO A WARMING TREND THAT WILL PERSIST INTO THE WEEKEND. BY LATE IN THE WORK WEEK A NORTHERN STREAM FLOW WILL ATTEMPT TO REESTABLISH ITSELF ACROSS THE WESTERN HALF OF THE CONUS AS THE FLOW ACROSS THE PACIFIC SPLITS. THIS MAKES FOR A MESSY PATTERN IN THE OFFING ACROSS THE PLAINS FOR NEXT WEEKEND...AND BY MESSY I MEAN HARD TO PIN DOWN WITH LOTS OF UNCERTAINTY. TEMPERATURES WILL MODERATE BACK TOWARDS SEASONALLY NORMAL VALUES AS THE PROGGED WEST COAST RIDGE MOVES SLOWLY EAST. HOWEVER...CONFIDENCE IN PLACEMENT OF ANY WAVES AND THEIR TIMING IS VERY POOR OWING TO THE SPLIT FLOW. THEREFORE...HAVE AVOIDED ATTACHING POPS TO ANY OF THE SHORTWAVES PROGGED TO COMING ZIPPING THROUGH PLAINS OVER THE LAST HALF OF THE FORECAST AT THIS TIME. CUTTER .PREV DISCUSSION... 505 AM... PRIMARY FORECAST CONCERN WILL BE THE POTENTIAL FOR A SIGNIFICANT WINTER STORM ACROSS THE AREA TO BEGIN THE WORK WEEK. CURRENT RUC ANALYSIS AND WV IMAGERY SHOWS NORTHWEST FLOW ALOFT OVER THE REGION WITH THE ANTICIPATED WINTER WEATHER PRODUCING UPPER WAVE FINALLY APPROACHING THE WEST COAST. SURFACE HIGH PRESSURE WAS GRADUALLY SHIFTING TO THE EAST THIS MORNING WHICH WILL ALLOW FOR SOUTHERLY WINDS AND INCREASING MOISTURE AHEAD OF THE APPROACHING UPPER SYSTEM. FORECAST GRIDS GENERALLY SIDED TOWARD THE GFS AND SREF GUIDANCE AS THEY HAVE BEEN THE MOST CONSISTENT WITH THERMAL FIELDS AND THE GFS HAS BEEN MORE CONSISTENT WITH ITS PLACEMENT WITH THE HEAVIER QPF. INITIAL CHANGE TO THE GRIDS WAS TO REDUCE POPS TONIGHT FROM LIKELY INTO THE CHANCE RANGE AS THE BETTER ISENTROPIC LIFT WON`T BE REACHING THE AREA UNTIL TOWARD DAWN. IN ADDITION...THE 21Z RUN OF THE SREF WAS POINTING MORE IN THE DIRECTION OF CHANCE POPS. STILL UNCERTAINTY REGARDING PRECIPITATION TYPES AND HOW FAST THE COLDER AIR WILL BE DRAWN SOUTHWARD AS SURFACE LOW TRACKS ACROSS THE RED RIVER VALLEY AND INTO LOWER MISSISSIPPI VALLEY BY TUESDAY. MEAN SREF DATA SHOWS BOTH THE SURFACE FREEZING LINE AND 0 DEG C LINE AT 850 MB ONLY MAKING VERY SLOW SOUTHWARD PROGRESS ACROSS THE AREA ON MONDAY...WITH THE PROGGED FREEZING LINE NOT MAKING IT TO THE METRO AREA UNTIL BETWEEN 21Z AND 00Z TUESDAY. HOWEVER...GFS POINT SOUNDINGS DO NOT SHOW A STRONG WARM LAYER ALOFT AND THERE IS CONCERN REGARDING HOW MUCH THE EXPECTED STRONG VERTICAL MOTION WILL COOL THE LOWER ATMOSPHERE. THE GFS HAS BEEN FAIRLY CONSISTENT IN BRINGING STRONG OMEGAS AND MID- LEVEL FRONTOGENESIS INTO THE NORTHERN HALF OF THE FORECAST AREA MONDAY INTO MONDAY EVENING. LOCATIONS NORTH OF THE INTERSTATE 70 CORRIDOR WILL LIKELY GET THE BEST FORCING AND HEAVIEST QPFS IS THIS FORCING PANS OUT. WILL START OUT THE SOUTHERN HALF OF THE FORECAST AREA AS ALL RAIN MONDAY MORNING...WITH A WINTERY MIX ACROSS OUR FAR NORTHERN 2 OR 3 TIERS OF COUNTIES. WILL ANTICIPATE THAT COLD AIR WILL MAKE PROGRESS TO THE SOUTH AND TRANSITION NORTHERN AREAS TO MAINLY SNOW DURING THE AFTERNOON...WITH AREAS ALONG THE INTERSTATE 70 CORRIDOR STARTING TO GET A WINTRY MIX...BUT RAIN HOLDING ON ACROSS FAR SOUTHERN AREAS THROUGH THE DURATION OF MONDAY AFTERNOON. BY LATE MONDAY EVENING...ALL AREAS SHOULD BE TRANSITIONING TO ALL SNOW. POINT SOUNDINGS DO NOT INDICATE LONG PERIODS OF ICE ACCUMULATIONS. THEY SHOW MORE OF A QUICK TRANSITION FROM RAIN TO SNOW ACROSS THE SOUTHERN HALF OF THE FORECAST AREA WITH ONLY A FEW HOUR TRANSITION PERIOD WHERE AN ICY MIX IS POSSIBLE. KEPT THE STORM TOTAL SNOW GRIDS AS IS SINCE IT DEPICTED THE HEAVIEST SNOW ACROSS FAR NORTHERN MISSOURI...AND WAS SIMILAR TO THE HPC GUIDANCE. LATER SHIFTS MAY NEED TO BUMP UP TOTALS FURTHER...AS CROSS- SECTIONS SHOW A NICE BULLSEYE OF LIFT WITHIN THE BEST TEMPERATURES FOR DENDRITIC ICE CRYSTAL GROWTH MONDAY AFTERNOON. IN ADDITION...THERE LOOKS TO BE PLENTY OF MOISTURE AS MIXING RATIOS ARE IN THE 3 TO 4 G/KG RANGE. WITH CONCERNS REGARDING PRECIP TYPE...DECIDED TO HOLD OFF ON UPPING TOTALS YET. FORECAST SNOW TOTALS ARE FOR AROUND 4 TO 6 INCHES ACROSS OUR NORTHERN 2 OR 3 TIERS OF COUNTIES WITH AMOUNTS LOWERING TO AN INCH OR TWO OVER FAR SOUTHERN AREAS BY THE TIME THE SNOW TAPERS OFF TUESDAY MORNING. WENT AHEAD AN HOISTED A WINTER STORM WATCH ACROSS FAR NORTHERN MISSOURI FROM 12Z MONDAY TO 12Z TUESDAY. THIS AREA STANDS THE BEST CHANCE OF GETTING COLD ENOUGH FOR HEAVIER SNOW...AND AS MENTIONED BEFORE WILL EXPERIENCE THE BETTER MID-LEVEL FORCING. IF COLDER AIR FILTERS IN FASTER THAN CURRENTLY EXPECTED...THIS WATCH MAY NEED TO BE EXPANDED SOUTHWARD. IN ADDITION TO THE SNOW...WINDS WILL INCREASE CAUSING BLOWING AND DRIFTING SNOW MONDAY NIGHT AS THE PRESSURE GRADIENT INCREASES WITH THE SURFACE LOW PASSING TO THE SOUTH. MADE NO OTHER CHANGES TO THE EXTENDED GRIDS. SAW && .EAX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WATCH FROM 6 AM MONDAY TO 12 PM TUESDAY FOR MOZ001-MOZ002-MOZ003-MOZ004-MOZ005-MOZ006-MOZ007-MOZ008-MOZ011- MOZ012-MOZ013-MOZ014-MOZ015-MOZ016-MOZ017. KS...NONE. $$ WFO EAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 505 AM CST SUN FEB 11 2007 .DISCUSSION... PRIMARY FORECAST CONCERN WILL BE THE POTENTIAL FOR A SIGNIFICANT WINTER STORM ACROSS THE AREA TO BEGIN THE WORK WEEK. CURRENT RUC ANALYSIS AND WV IMAGERY SHOWS NORTHWEST FLOW ALOFT OVER THE REGION WITH THE ANTICIPATED WINTER WEATHER PRODUCING UPPER WAVE FINALLY APPROACHING THE WEST COAST. SURFACE HIGH PRESSURE WAS GRADUALLY SHIFTING TO THE EAST THIS MORNING WHICH WILL ALLOW FOR SOUTHERLY WINDS AND INCREASING MOISTURE AHEAD OF THE APPROACHING UPPER SYSTEM. FORECAST GRIDS GENERALLY SIDED TOWARD THE GFS AND SREF GUIDANCE AS THEY HAVE BEEN THE MOST CONSISTENT WITH THERMAL FIELDS AND THE GFS HAS BEEN MORE CONSISTENT WITH ITS PLACEMENT WITH THE HEAVIER QPF. INITIAL CHANGE TO THE GRIDS WAS TO REDUCE POPS TONIGHT FROM LIKELY INTO THE CHANCE RANGE AS THE BETTER ISENTROPIC LIFT WON`T BE REACHING THE AREA UNTIL TOWARD DAWN. IN ADDITION...THE 21Z RUN OF THE SREF WAS POINTING MORE IN THE DIRECTION OF CHANCE POPS. STILL UNCERTAINTY REGARDING PRECIPITATION TYPES AND HOW FAST THE COLDER AIR WILL BE DRAWN SOUTHWARD AS SURFACE LOW TRACKS ACROSS THE RED RIVER VALLEY AND INTO LOWER MISSISSIPPI VALLEY BY TUESDAY. MEAN SREF DATA SHOWS BOTH THE SURFACE FREEZING LINE AND 0 DEG C LINE AT 850 MB ONLY MAKING VERY SLOW SOUTHWARD PROGRESS ACROSS THE AREA ON MONDAY...WITH THE PROGGED FREEZING LINE NOT MAKING IT TO THE METRO AREA UNTIL BETWEEN 21Z AND 00Z TUESDAY. HOWEVER...GFS POINT SOUNDINGS DO NOT SHOW A STRONG WARM LAYER ALOFT AND THERE IS CONCERN REGARDING HOW MUCH THE EXPECTED STRONG VERTICAL MOTION WILL COOL THE LOWER ATMOSPHERE. THE GFS HAS BEEN FAIRLY CONSISTENT IN BRINGING STRONG OMEGAS AND MID- LEVEL FRONTOGENESIS INTO THE NORTHERN HALF OF THE FORECAST AREA MONDAY INTO MONDAY EVENING. LOCATIONS NORTH OF THE INTERSTATE 70 CORRIDOR WILL LIKELY GET THE BEST FORCING AND HEAVIEST QPFS IS THIS FORCING PANS OUT. WILL START OUT THE SOUTHERN HALF OF THE FORECAST AREA AS ALL RAIN MONDAY MORNING...WITH A WINTERY MIX ACROSS OUR FAR NORTHERN 2 OR 3 TIERS OF COUNTIES. WILL ANTICIPATE THAT COLD AIR WILL MAKE PROGRESS TO THE SOUTH AND TRANSITION NORTHERN AREAS TO MAINLY SNOW DURING THE AFTERNOON...WITH AREAS ALONG THE INTERSTATE 70 CORRIDOR STARTING TO GET A WINTRY MIX...BUT RAIN HOLDING ON ACROSS FAR SOUTHERN AREAS THROUGH THE DURATION OF MONDAY AFTERNOON. BY LATE MONDAY EVENING...ALL AREAS SHOULD BE TRANSITIONING TO ALL SNOW. POINT SOUNDINGS DO NOT INDICATE LONG PERIODS OF ICE ACCUMULATIONS. THEY SHOW MORE OF A QUICK TRANSITION FROM RAIN TO SNOW ACROSS THE SOUTHERN HALF OF THE FORECAST AREA WITH ONLY A FEW HOUR TRANSITION PERIOD WHERE AN ICY MIX IS POSSIBLE. KEPT THE STORM TOTAL SNOW GRIDS AS IS SINCE IT DEPICTED THE HEAVIEST SNOW ACROSS FAR NORTHERN MISSOURI...AND WAS SIMILAR TO THE HPC GUIDANCE. LATER SHIFTS MAY NEED TO BUMP UP TOTALS FURTHER...AS CROSS- SECTIONS SHOW A NICE BULLSEYE OF LIFT WITHIN THE BEST TEMPERATURES FOR DENDRITIC ICE CRYSTAL GROWTH MONDAY AFTERNOON. IN ADDITION...THERE LOOKS TO BE PLENTY OF MOISTURE AS MIXING RATIOS ARE IN THE 3 TO 4 G/KG RANGE. WITH CONCERNS REGARDING PRECIP TYPE...DECIDED TO HOLD OFF ON UPPING TOTALS YET. FORECAST SNOW TOTALS ARE FOR AROUND 4 TO 6 INCHES ACROSS OUR NORTHERN 2 OR 3 TIERS OF COUNTIES WITH AMOUNTS LOWERING TO AN INCH OR TWO OVER FAR SOUTHERN AREAS BY THE TIME THE SNOW TAPERS OFF TUESDAY MORNING. WENT AHEAD AN HOISTED A WINTER STORM WATCH ACROSS FAR NORTHERN MISSOURI FROM 12Z MONDAY TO 12Z TUESDAY. THIS AREA STANDS THE BEST CHANCE OF GETTING COLD ENOUGH FOR HEAVIER SNOW...AND AS MENTIONED BEFORE WILL EXPERIENCE THE BETTER MID-LEVEL FORCING. IF COLDER AIR FILTERS IN FASTER THAN CURRENTLY EXPECTED...THIS WATCH MAY NEED TO BE EXPANDED SOUTHWARD. IN ADDITION TO THE SNOW...WINDS WILL INCREASE CAUSING BLOWING AND DRIFTING SNOW MONDAY NIGHT AS THE PRESSURE GRADIENT INCREASES WITH THE SURFACE LOW PASSING TO THE SOUTH. MADE NO OTHER CHANGES TO THE EXTENDED GRIDS. SAW && .PREV DISCUSSION... /ISSUED 430 PM CST SAT FEB 10 2007/ DISCUSSION... SIGNIFICANT WINTER SYSTEM WILL AFFECT THE REGION BEGINNING SUNDAY EVENING AND LASTING INTO TUESDAY. IN THE NEAR TERM WEAK WARM ADVECTION AND STRUNG OUT VORTICITY AIDING BAND OF MID CLOUDS STREAMING THROUGH CWA. THERE ARE ALSO SOME LOWER UPSTREAM MID CLOUDS WHICH WILL TRACK ACROSS THE NORTHERN HALF OF THE CWA OVERNIGHT. SOUTHWEST 1/4 OF CWA MAY NOT SEE MUCH CLOUD COVER TILL TOMORROW. FOLLOWED MAV/MET MOS NUMBERS WHICH WERE CLOSE TO THE GOING LOW TEMPERATURE FORECAST FOR TONIGHT. ATTENTION THEN TURNS TO SUNDAY AS SHORTWAVE NOW APPROACHING THE CA COAST IS PROGGED TO DEEPEN AS IT MOVES ACROSS THE CENTRAL/SOUTHERN ROCKIES AND INTO THE SOUTHERN PLAINS ON MONDAY. EACH OF THE PAST COUPLE MODEL RUNS OF THE GFS AND NAM THROUGH THE 18Z RUN TODAY HAS COME IN WITH PROGRESSIVELY WARMER BOUNDARY LAYER TEMPERATURES AS WELL AS DELAYING THE ONSET OF PRECIPITATION. NONETHELESS STILL BELIEVE THE WARM ADVECTION AS NOTED SPECIFICALLY ON THE 300K ISENTROPIC CHART WILL GENERATE THE FIRST SALVO OF PRECIPITATION SUNDAY EVENING. HOW MUCH WARM AIR CAN BE BROUGHT NORTHWARD TOMORROW AND TOMORROW NIGHT WILL GO A LONG WAYS TOWARDS DETERMINING PRECIPITATION TYPES. GIVEN THE STRENGTH OF THE WARM AIR ADVECTION AND KNOWING THAT HEAVY SNOWFALL NEEDS THE COLD AIR TO BE IN PLACE AHEAD OF TIME IN MOST CASES HAVE SHIFTED THE THREAT FOR SIGNIFICANT SNOW OVER THE NORTHERN 1/4 OF THE CWA. WENT CONSERVATIVE ON SNOW AMOUNTS DUE TO UNCERTAINTY ON HOW FAR NORTH ABOVE FREEZING TEMPERATURES WILL END UP PLUS THE LACK OF CONFIDENCE IN THE THERMAL PROFILES AS WARM NOSES COULD EASILY SHOW UP IN FUTURE MODEL RUNS AND THUS DISTORT THE SNOW ACCUMULATIONS. THE CURRENT THERMAL PROFILES ALSO SUGGEST MENTIONED THE POTENTIAL FOR FREEZING RAIN AND SLEET. THAT BEING SAID HAVE TO BE IMPRESSED WITH THE 4-6G/KG OF MOISTURE AVAILABLE ON THE 300K SURFACE AND WITH THE POSSIBILITY IT COULD SNOW FOR 18-24 HOURS ACROSS NORTHERN MO THERE CERTAINLY COULD BE MUCH MORE THAN THE 6 INCHES CURRENTLY FORECAST FOR FAR NORTHERN MO. DID NOT GO WITH HEADLINES THIS FORECAST PACKAGE DUE TO THE DISCREPANCIES BETWEEN THE NAM/GFS/SREF ON PLACEMENT OF HEAVIEST QPF AND THE FACT THAT THE SYSTEM HAS NOT EVEN REACHED THE WEST COAST. SO THERE IS PLENTY OF TIME TO REFINE THE PLACEMENT OF A WINTER STORM WATCH AS WELL AS DETERMINE A MORE EXACT PLACEMENT OF THE HEAVY SNOW THREAT. MJ TUESDAY-SATURDAY... WITH THE LATEST MODEL RUNS IT LOOKS AS IF THE TAIL END OF OUR SUNDAY NIGHT/EARLY WORK WEEK WINTER STORM SYSTEM WILL BE JUST LEAVING THE FORECAST AREA DURING THE DAYLIGHT HOURS TUESDAY. THE WRF/GFS/AND ECMWF HAVE ALL FOLLOWED THIS SLOWING TREND WITH THE LATE WEEKEND SYSTEM...SWINGING THE ASSOCIATED SURFACE LOW A LITTLE FARTHER NORTH THAN PREVIOUS RUNS. FOR NOW THE UPSHOT OF THE MEDIUM RANGE MODEL ADJUSTMENTS IS TO ADD IN CHANCE SNOW ACCUMULATIONS TO THE DAYLIGHT HOURS OF TUESDAY. ON THE UPSIDE TEMPERATURE PROFILES BY TUESDAY INDICATE THAT TEMPERATURES EVERYWHERE SHOULD BE AT OR BELOW FREEZING MAKING FOR A SIMPLER PRECIPITATION TYPE FORECAST...SNOW. HOWEVER...HAVE KEPT THE SNOW ACCUMULATIONS FOR TUESDAY MUTED TO UNDER AN INCH AS THERE IS STILL CONSIDERABLE UNCERTAINTY IN THE EXACT EXIT TIMING. OTHERWISE...IN THE WAKE OF THE EARLY WORK WEEK WINTER STORM SOME COLD CANADIAN HIGH PRESSURE WILL SURGE SOUTH INTO THE PLAINS. BOTH THE GFS AND ECMWF SHOW THE SURFACE HIGH STARTING OUT GREATER THAN 1040MB AS IT SLIDES SOUTH INTO THE STATES...BUT IT BEGINS TO MODIFY AS IT SETTLES THROUGH THE PLAINS TO AROUND 1035MB BY THURSDAY MORNING. CANADIAN MODEL IS MUCH MORE AGRESSIVE WITH THE COLD AIR KEEPING THE SURFACE HIGH ABOVE 1040MB THROUGH FRIDAY NIGHT. THIS MAKES THE CANADIAN THE SLOWEST AT MOVING THE SURFACE COLD POOL OUT OF THE PLAINS. ALSO...THE GFS AND ECMWF ARE SIMILAR IN BUCKLING THE STRONG ZONAL JET...THAT WILL PREVAIL ACROSS THE SOUTHERN CONUS THIS COMING WEEK...ALONG THE WEST COAST LATE IN THE WORK WEEK. THINK THIS SHOULD HELP SHOVE THE SURFACE HIGH TO THE SOUTHEAST BY NEXT WEEKEND. HOWEVER...I HAVE KEPT TEMPERATURES AT OR JUST BELOW MEX GUIDANCE THROUGH THE WEEKEND GIVEN THE NORTHWEST FLOW THAT WILL BE REESTABLISHING ITSELF ACROSS THE PLAINS. CUTTER && .EAX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WATCH FROM 6 AM MONDAY TO 6 AM TUESDAY FOR MOZ001- MOZ002-MOZ003-MOZ004-MOZ005-MOZ006-MOZ007-MOZ008-MOZ011- MOZ012-MOZ013-MOZ014-MOZ015-MOZ016-MOZ017. KS...NONE. $$ WFO EAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 503 PM CST SAT FEB 10 2007 .DISCUSSION... THE 12Z SHORT-TERM MODELS (TIL TUESDAY)...GENERAL PATTERN AT H500 THAT WE HAVE SEEN THE PAST FEW DAYS WITH LONGWAVE TROF OVER ERN NOAM AND NWLY FLOW OVER THE MS VALLEY WILL EVOLVE INTO A SPLIT FLOW PATTERN BY EARLY NEXT WEEK. THREE SHORTWAVES TO AFFECT OUR REGION DURING THIS TIME...WITH THE FIRST TONIGHT...BUT WITH LITTLE MOISTURE TO WORK WITH THIS WILL NOT PRODUCE PCPN BUT JUST AN AREA OF MID CLOUD...THE SECOND SHORTWAVE ON SUNDAY NIGHT WILL BE A LEAD IMPULSE FROM A SRN STREAM SYSTEM TO APPROACH EARLY NEXT WEEK...AND THEN THE MAIN SHORTWAVE TO IMPACT THE AREA MONDAY THRU TUESDAY. AT THE SURFACE...HI PRES WILL SLIDE TO THE SE TONIGHT WITH SLY FLOW ON SUNDAY. CDFNT WILL THEN APPROACH FROM THE N SUNDAY NIGHT AND MOVE THRU MONDAY AS A WAVE OF LO PRES ORGANIZES AND RIDES ALONG THE FRONT THRU NRN AR AND WRN TN DURING MONDAY NIGHT AND TUESDAY. AN ARCTIC HI PRES THEN BEGINS TO BUILD IN FOR TUESDAY. MAIN WX STORY WILL BE ON THE IMPENDING STORM FOR LATE SUNDAY NIGHT THRU TUESDAY. MODEL TRENDS HAVE BEEN FOR A WARMER SOLUTION THRU THE COLUMN...AS WELL AS A SLOWER PROGRESSING STORM THRU OUR PART OF THE CONUS. THIS WILL PUSH ACCUMULATING SNOW AND ICE FURTHER N...BUT WILL BE PARTIALLY MADE UP IN OUR AREA BY THE LAGGING STORM LATE MONDAY NIGHT INTO TUESDAY. WITH A FAIR AMOUNT OF DRY AIR TO OVERCOME INITIALLY...EVAPORATIONAL COOLING WILL PLAY A ROLE IN DETERMINING P-TYPES LATE SUNDAY NIGHT INTO MONDAY...DEPENDING ON HOW FAST PCPN MOVES IN...WITH SOME MODELS SUCH AS THE GFS MOVING IT IN BY LATE SUNDAY NIGHT FOR MOST LOCATIONS AND OTHERS LIKE THE NAM MUCH SLOWER IN DEVELOPING IT. WITH RATHER STRONG DYNAMICS PUSHING INTO THE AREA WITH THE LEAD IMPULSE ON SUNDAY NIGHT...TENDED TO FAVOR THE FASTER GFS ON TIMING. H700 LO CENTER NOT EXPECTED TO DEVELOP TIL MONDAY AFTERNOON...AND THEN UPSTREAM FROM OUR FA...SO TIL THEN...LOOK FOR WEDGE OF WARM AIR TO DEVELOP ALOFT AND RESULT IN A WINTRY MIX FOR AREAS GENERALLY N AND NE OF ST LOUIS...ALTHOUGH A BRIEF WINTRY MIX FOR OTHER AREAS AT THE INITIAL ONSET NOT OUT OF THE QUESTION. H700 LO CENTER WILL THEN TRACK ACROSS NRN MO/CNTRL IL MONDAY NIGHT SETTING UP THE NRN LIMITS OF THE WARM WEDGE OF AIR ALOFT AS WELL AS WHERE THE BETTER BANDED SNOW WILL SETUP. IT IS THERE WHERE THE BEST SNOW TOTALS ARE EXPECTED TO BE FOUND...POSSIBLY EXCEEDING 6 INCHES BEFORE THE EVENT ENDS TUESDAY MORNING. WARM WEDGE OF AIR ALOFT ELSEWHERE WILL MAINTAIN EITHER JUST A COLD RAIN OR...WHERE TEMPS CAN EDGE CLOSER TO OR JUST BELOW THE FREEZING MARK...A WINTRY MIX WITH MINOR ICE ACCUMS. HOWEVER...ADD TO THIS THAT WE ARE TRACKING A /MOVING TARGET/ ON MODEL SOLUTIONS AND THAT THIS IS ALL EXPECTED TO OCCUR FROM THE 4TH THRU 6TH PERIODS OF THE FORECAST...AND CONFIDENCE IN A WARNING CRITERIA EVENT IS JUST A HAIR BELOW 50PCT AT THIS TIME...AND SO WILL DEFER ANY WATCH DECISION TO THE MID SHIFT. FOR THE EXTENDED PERIOD (TUESDAY NIGHT - SATURDAY)...SIGNIFICANT DIFFERENCES EXIST BETWEEN THE MODELS ON HOW TO HANDLE THE NRN STREAM AND THE H500 POLAR VORTEX THAT IS EXPECTED TO BEGIN THIS PERIOD JUST NW OF THE GREAT LAKES REGION. THE UKMET/ECMWF/NOGAPS/CMC WANT TO LINGER THIS POLAR VORTEX AROUND FOR MUCH OF NEXT WEEK AND RESULT IN A SERIES OF NRN STREAM SHORTWAVES MOVING THRU WHILE THE GFS/DGEX SUGGESTS A MORE PROGRESSIVE SOLUTION. EVEN THE MODELS THAT WANT TO MAINTAIN POLAR VORTEX DO SO IN VARYING DEGREES AND FOR NOW PLAN ON GOING WITH A MIDDLE-OF-THE-ROAD CONSENSUS SOLUTION BETWEEN THEM WHICH SLOWLY PULLS POLAR VORTEX AWAY FROM THE GREAT LAKES BY LATE WEEK. AT THE SURFACE...THINGS ARE MORE OR LESS THE SAME WITH COLD ARCTIC HI PRES BUILDING INTO THE AREA THRU FRIDAY AND THEN OUR REGION IS ON THE BACKSIDE OF THIS HI ON SATURDAY WITH A FRONT EXPECTED TO PUSH THRU LATE SATURDAY. AM EXPECTING A DRY AND LARGELY COLD PERIOD...WITH SPLIT FLOW NOT TOO FAVORABLE FOR ANY SIGNFICANT PCPN EVENTS. THE ONLY SRN STREAM SHORTWAVE THAT MIGHT BE ABLE TO DELIVER SOME PCPN IS EXPECTED TO PASS TO OUR S ON THURSDAY. TES && .AVIATION... FOR THE 18Z TAFS...MID LVL CLOUDINESS OVR NWRN MO WILL BE SPREADING E-SEWD THRU THE TAF SITES THIS AFTN AND THIS EVNG. LATEST RUC RH ANALYSIS HAS 80 PERCENT OR GREATER RH VALUES AT 700 MB OVER ALL THE TAF SITES BY 03Z SUN. SFC HI CNTRD OVR NWRN MO SWRN IA WILL MOVE E-SEWD THRU THE CWA THIS AFTN AND THIS EVNG. NWLY SFC WNDS WILL BCM LGT BY LT AFTN AND EARLY EVNG UNDERNEATH SFC HI...THEN THE SFC WND WL BCM S-SELY LT TGT AND SUN MRNG ON THE WEST SIDE OF THE SFC RDG. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1027 PM EST SAT FEB 10 2007 .SHORT TERM /REST OF TONIGHT THROUGH TUESDAY/... LAKE EFFECT SNOW BANDS HAVE BECOME MORE DIFFUSE BUT HAVE REORIENTED MORE FROM 300 DEGREE IN A LL CONVERGENT REGION ALONG THE LONG AXIS OF LAKE ONTARIO. SUBSDC HAS KICKED IN AND THE WINDS HAVE SHIFTED SOMEWHAT TO THE NW AT LEAST ABV THE SFC LAYER. THIS CAN BE SEEN SOMEWHAT ON THE TYX 88D VWP. SFC WINDS ARE MORE SWRLY. THE SHEARING HAS LIKELY LESSONED THE INTENSITY OF THE LAKE EFFECT SOME. KEPT ADVY TOTAL SNOW AMNTS MAINLY FOR FAR NRN PARTS OF ONONDAGA AND MADISON AND CENTRAL ONEIDA. SHRT WAVE CURRENTLY SEEN WELL MOVG INTO THE WRN GREAT LAKES WILL BACK THE FLO ENUF TO POTENTIALLY RE-ORGANIZE THE LES BANDS AS THEY SHIFT NORTH BACK INTO NORTHERN ONEIDA COUNTY. WILL KEEP WARNINGS GOING SINCE WARNING CRITERIA HAS ALREADY BEEN MET UP IN NRN ONEIDA AND THIS NEXT BAND WILL ADD TO THE SNOWFALL. SOME LAKE ERIE SNOW BANDS WILL CONT TO AFFECT STEUBEN CO TO THE WRN FINGER LAKES OVRNGT. REST OF CWA...PC SKIES FEW FLURRIES IN C NY...MAINLY CLR IN NE PA OVERNIGHT. && .PREV DISCUSSION... /ISSUED 747 PM EST SAT FEB 10 2007/ SHORT TERM /REST OF TONIGHT THROUGH TUESDAY/... LAKE EFFECT SNOWS CONTINUE TO HIT NORTHERN ONEIDA COUNTY. THE RADAR ECHOES HAVE DIMINISH SOME AS SUBSDC DRYING BEHIND A SHRT WAVE LIKELY IS LOWERING INVERSION SOME. IN ADDITION A MORE NWRLY FLO HAS SET UP ACRS NRN LAKE ONT WITH SW LL WINDS SOUTH OF THE LAKE. CONVERGENCE WAS INCREASING IN AN AXIS THAT SEEMS TO BE FAVORING A NEW BAND TO RE-ORGANIZE FARTHER SOUTH ACRS FAR NORTHERN ONONDAGA COUNTY...FAR NORTHERN MADISON COUNTY AND TO THE THRUWAY IN ONIEDA COUNTY. MODEL SOUNDINGS FROM RUC...WRF ALL SUGGEST A MAJOR SHIFT TO NW WINDS IN THE LL/S THAT JUST IS NOT APPEARING IN THE VWP DATA OR IN THE SFC DATA. THEREFORE AM NOT GOING ANY FARTHER SOUTH WITH THE LAKE EFFECT BANDS THAN THE THRUWAY. THE LL FLOW WAS ALSO BACKING IN SRN ONT IN RESPONSE TO ANTHR SHRT WAVE MOVING INTO THE GREAT LAKES. THIS WAVE WILL REORGANIZE THE LAKE EFFECT BANDS LATER TONIGHT SHIFT THEM BACK NORTH ACR NRN ONEIDA COUNTY AGAIN FOR A TIME...UNTIL LATE SUNDAY MORNING (THE LATEST). ISSUED ADVY 3-7 INCHES FROM THRUWAY SYR-UCA AND NORTH TO RME. NORTH OF THERE WARNING SNOWS WILL CONT. S OF THRUWAY 1-3 INCHES AT BEST. ALSO HAVE SOME LES SNOWS AFFECTING FAR WESTERN STUEBEN CO AND YATES CO/S OVR THE HIGHER TERRAIN. SEE SUB-ADVY CRITERIA SNOWS IN THESE AREAS. 1-3 INCHES HIGHER TERRAIN. REST OF CWA...PC SKIES AND A FEW FLURRIES...JUST QUIET AND COLD. NEXT SHORT TERM UPDATE BY 10 PM OR SO. AVIATION /01Z-24Z/... FOR KSYR AND KRME...LAKE EFFECT SNOWS WILL BRING PERIODS OF IFR OVERNIGHT. FOR KSYR...IMPROVEMENT IS ANTICIPATED AFTER ABOUT 09Z...AS THE LAKE BAND SHIFTS NORTH OF THIS TERMINAL. AT KRME...NOTICEABLE IMPROVEMENT IS NOT EXPECTED UNTIL AFTER ABOUT 12Z SUNDAY. ELSEWHERE OVERNIGHT...MAINLY VFR IS ANTICIPATED. WESTERLY WINDS OF 10-15 KT THIS EVENING...WILL BACK TO THE SOUTHWEST...AND DIMINISH TO 5-10 KT AFTER 06Z. DURING THE DAY SUNDAY...LOOK FOR VFR AREA-WIDE...WITH SOUTHWEST WINDS NEAR 10 KT. PREV DISCUSSION... /ISSUED 318 PM EST SAT FEB 10 2007/ SHORT TERM /TONIGHT THROUGH TUESDAY/... SAME OLD SONG AND DANCE AS LK ONTARIO REFUSES TO SHUT OFF. CONNECTION HAS NOW BEEN MADE TO LK HURON WITH LONG BAND STREAMING ACROSS CENTER AXIS OF LAKE AND INTO OSWEGO/NRN ONEIDA COUNTY. SNOWFALL RATES IN THIS BAND BEING REPORTED AT 4 INCHES PER HOUR IN CENTRAL OSWEGO COUNTY. BAND WILL REMAIN NEARLY STATIONARY OVER NRN ONEIDA COUNTY THIS EVENING...WITH A POSSIBLE FLUCTUATION TO THE NORTH BTWN 21Z AND 00Z. TROF LOCATED OVER CENTRAL LK ONTARIO WILL RESULT IN A MORE NWRLY FLOW LATE THIS EVENING...POSSIBLY DROPPING BAND INTO SRN ONEIDA COUNTY BTWN 03-06Z AND THEN INTO EXTREME NRN ONONDAGA/MADISON CTY. HOWEVER AT THE SAME TIME...INVERSION BEGINS CRASHING AND LIFT DIMINISHES. AM EXPECTING SNOWFALL RATES TO DECREASE AFTER MIDNIGHT TONIGHT. SNOW ACCUMS OF 2-4 INCHES EXPECTED OVER ONONDAGA AND MADISON COUNTIES TONIGHT. FOR ONEIDA...COULD SEE SLIGHTLY HIGHER AMOUNTS NORTH OF THE ROME UTICA AREA OVERNIGHT. BUT AM EXPECTING ACCUMS TO REMAIN JUST BLO ADVISORY CRITERIA AS BAND OSCILLATES NORTH AND SOUTH THIS EVENING. HAVE CONTD WARNING FOR NRN ONEIDA WITH 2-4 INCH PER HOUR AMOUNTS POSSIBLE THRU THE EVENING BEFORE DIMINISHING. COULD SEE STORM TOTALS EXCEEDING A FOOT BY MORNING...MOST OF IT FALLING BTWN NOW AND MIDNIGHT. REMAINDER OF AREA SHOULD SEE FEW LIGHT SNOW SHOWERS AND/OR FLURRIES THIS EVENING BEFORE CLEARING OUT. LAKE EFFECT SNOW EXPECTED TO SHIFT NORTH OF FA MID-MORNING SUNDAY...WITH FAIR AMOUNT OF SUNSHINE OVER MOST OF THE REGION. ON SUNDAY NIGHT NEXT SYSTEM MOVES EAST OVER CANADA AND DRAGS AND ARCTIC CLD FRONT WITH IT. FRONT WILL APPROACH UPSTATE NY MONDAY MORNING AND MOVE THRU FA DURING THE DAY MONDAY. AS WAS THE CASE LAST TIME...BRIEF SQUALLS COULD ACCOMPANY FRONT...ESPECIALLY OVER NRN ZONES WITH LESS CHC OVER NEPA. LOW LEVEL CONVERGENCE DOES NOT APPEAR TO BE AS STRONG WITH THIS FRONT ALTHOUGH MAY BE ENOUGH TO PRODUCE A QUICK 1-3 INCHES NORTH AND CENTRAL. AFTER PASSAGE...NRLY FLOW USHERING IN COLD CANADIAN AIR...WITH BAROCLINIC ZONE SETTING UP SOUTH OF REGION THRU TUESDAY AFTERNOON. LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... FOLLOWED HPC GUIDANCE. SAME PATTERN CONTINUES FOR EXTENDED. NW FLOW WITH COLD AIR. A LARGE CONTINENTAL ARCTIC HIGH BUILDS INTO THE PLAINS WHILE A STORM HEADS EAST ACROSS THE MID ATLANTIC. STILL QUESTIONS ON HOW FAR N THE SNOW WILL COME TUESDAY NIGHT AND WED. THE COLD AIR WILL KEEP MOST OF THE SNOW OUT OF NY WITH ONLY LGT SNOW IN PA. WITH VARIED MODEL OUTPUT AND LOW HPC CONFIDENCE WILL CONTINUE WITH CHC POPS. AS THIS STORM EXITS ANOTHER SHOT OF COLD AIR AND LES WILL RETURN FOR WED TO FRI. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST SUNDAY FOR NYZ018-036- 037. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST SUNDAY FOR NYZ009. PA...NONE. && $$ SHORT TERM...DJN ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 747 PM EST SAT FEB 10 2007 .SHORT TERM /REST OF TONIGHT THROUGH TUESDAY/... LAKE EFFECT SNOWS CONTINUE TO HIT NORTHERN ONEIDA COUNTY. THE RADAR ECHOES HAVE DIMINISH SOME AS SUBSDC DRYING BEHIND A SHRT WAVE LIKELY IS LOWERING INVERSION SOME. IN ADDITION A MORE NWRLY FLO HAS SET UP ACRS NRN LAKE ONT WITH SW LL WINDS SOUTH OF THE LAKE. CONVERGENCE WAS INCREASING IN AN AXIS THAT SEEMS TO BE FAVORING A NEW BAND TO RE-ORGANIZE FARTHER SOUTH ACRS FAR NORTHERN ONONDAGA COUNTY...FAR NORTHERN MADISON COUNTY AND TO THE THRUWAY IN ONIEDA COUNTY. MODEL SOUNDINGS FROM RUC...WRF ALL SUGGEST A MAJOR SHIFT TO NW WINDS IN THE LL/S THAT JUST IS NOT APPEARING IN THE VWP DATA OR IN THE SFC DATA. THEREFORE AM NOT GOING ANY FARTHER SOUTH WITH THE LAKE EFFECT BANDS THAN THE THRUWAY. THE LL FLOW WAS ALSO BACKING IN SRN ONT IN RESPONSE TO ANTHR SHRT WAVE MOVING INTO THE GREAT LAKES. THIS WAVE WILL REORGANIZE THE LAKE EFFECT BANDS LATER TONIGHT SHIFT THEM BACK NORTH ACR NRN ONEIDA COUNTY AGAIN FOR A TIME...UNTIL LATE SUNDAY MORNING (THE LATEST). ISSUED ADVY 3-7 INCHES FROM THRUWAY SYR-UCA AND NORTH TO RME. NORTH OF THERE WARNING SNOWS WILL CONT. S OF THRUWAY 1-3 INCHES AT BEST. ALSO HAVE SOME LES SNOWS AFFECTING FAR WESTERN STUEBEN CO AND YATES CO/S OVR THE HIGHER TERRAIN. SEE SUB-ADVY CRITERIA SNOWS IN THESE AREAS. 1-3 INCHES HIGHER TERRAIN. REST OF CWA...PC SKIES AND A FEW FLURRIES...JUST QUIET AND COLD. NEXT SHORT TERM UPDATE BY 10 PM OR SO. && .AVIATION /01Z-24Z/... FOR KSYR AND KRME...LAKE EFFECT SNOWS WILL BRING PERIODS OF IFR OVERNIGHT. FOR KSYR...IMPROVEMENT IS ANTICIPATED AFTER ABOUT 09Z...AS THE LAKE BAND SHIFTS NORTH OF THIS TERMINAL. AT KRME...NOTICEABLE IMPROVEMENT IS NOT EXPECTED UNTIL AFTER ABOUT 12Z SUNDAY. ELSEWHERE OVERNIGHT...MAINLY VFR IS ANTICIPATED. WESTERLY WINDS OF 10-15 KT THIS EVENING...WILL BACK TO THE SOUTHWEST...AND DIMINISH TO 5-10 KT AFTER 06Z. DURING THE DAY SUNDAY...LOOK FOR VFR AREA-WIDE...WITH SOUTHWEST WINDS NEAR 10 KT. && .PREV DISCUSSION... /ISSUED 318 PM EST SAT FEB 10 2007/ SHORT TERM /TONIGHT THROUGH TUESDAY/... SAME OLD SONG AND DANCE AS LK ONTARIO REFUSES TO SHUT OFF. CONNECTION HAS NOW BEEN MADE TO LK HURON WITH LONG BAND STREAMING ACROSS CENTER AXIS OF LAKE AND INTO OSWEGO/NRN ONEIDA COUNTY. SNOWFALL RATES IN THIS BAND BEING REPORTED AT 4 INCHES PER HOUR IN CENTRAL OSWEGO COUNTY. BAND WILL REMAIN NEARLY STATIONARY OVER NRN ONEIDA COUNTY THIS EVENING...WITH A POSSIBLE FLUCTUATION TO THE NORTH BTWN 21Z AND 00Z. TROF LOCATED OVER CENTRAL LK ONTARIO WILL RESULT IN A MORE NWRLY FLOW LATE THIS EVENING...POSSIBLY DROPPING BAND INTO SRN ONEIDA COUNTY BTWN 03-06Z AND THEN INTO EXTREME NRN ONONDAGA/MADISON CTY. HOWEVER AT THE SAME TIME...INVERSION BEGINS CRASHING AND LIFT DIMINISHES. AM EXPECTING SNOWFALL RATES TO DECREASE AFTER MIDNIGHT TONIGHT. SNOW ACCUMS OF 2-4 INCHES EXPECTED OVER ONONDAGA AND MADISON COUNTIES TONIGHT. FOR ONEIDA...COULD SEE SLIGHTLY HIGHER AMOUNTS NORTH OF THE ROME UTICA AREA OVERNIGHT. BUT AM EXPECTING ACCUMS TO REMAIN JUST BLO ADVISORY CRITERIA AS BAND OSCILLATES NORTH AND SOUTH THIS EVENING. HAVE CONTD WARNING FOR NRN ONEIDA WITH 2-4 INCH PER HOUR AMOUNTS POSSIBLE THRU THE EVENING BEFORE DIMINISHING. COULD SEE STORM TOTALS EXCEEDING A FOOT BY MORNING...MOST OF IT FALLING BTWN NOW AND MIDNIGHT. REMAINDER OF AREA SHOULD SEE FEW LIGHT SNOW SHOWERS AND/OR FLURRIES THIS EVENING BEFORE CLEARING OUT. LAKE EFFECT SNOW EXPECTED TO SHIFT NORTH OF FA MID-MORNING SUNDAY...WITH FAIR AMOUNT OF SUNSHINE OVER MOST OF THE REGION. ON SUNDAY NIGHT NEXT SYSTEM MOVES EAST OVER CANADA AND DRAGS AND ARCTIC CLD FRONT WITH IT. FRONT WILL APPROACH UPSTATE NY MONDAY MORNING AND MOVE THRU FA DURING THE DAY MONDAY. AS WAS THE CASE LAST TIME...BRIEF SQUALLS COULD ACCOMPANY FRONT...ESPECIALLY OVER NRN ZONES WITH LESS CHC OVER NEPA. LOW LEVEL CONVERGENCE DOES NOT APPEAR TO BE AS STRONG WITH THIS FRONT ALTHOUGH MAY BE ENOUGH TO PRODUCE A QUICK 1-3 INCHES NORTH AND CENTRAL. AFTER PASSAGE...NRLY FLOW USHERING IN COLD CANADIAN AIR...WITH BAROCLINIC ZONE SETTING UP SOUTH OF REGION THRU TUESDAY AFTERNOON. LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... FOLLOWED HPC GUIDANCE. SAME PATTERN CONTINUES FOR EXTENDED. NW FLOW WITH COLD AIR. A LARGE CONTINENTAL ARCTIC HIGH BUILDS INTO THE PLAINS WHILE A STORM HEADS EAST ACROSS THE MID ATLANTIC. STILL QUESTIONS ON HOW FAR N THE SNOW WILL COME TUESDAY NIGHT AND WED. THE COLD AIR WILL KEEP MOST OF THE SNOW OUT OF NY WITH ONLY LGT SNOW IN PA. WITH VARIED MODEL OUTPUT AND LOW HPC CONFIDENCE WILL CONTINUE WITH CHC POPS. AS THIS STORM EXITS ANOTHER SHOT OF COLD AIR AND LES WILL RETURN FOR WED TO FRI. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...LAKE EFFECT SNOW ADVISORY UNTIL 4 AM EST SUNDAY FOR NYZ018-036- 037. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST SUNDAY FOR NYZ009. PA...NONE. && $$ SHORT TERM...DJN AVIATION...MLJ ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE RALEIGH NC 954 AM EST SAT FEB 10 2007 .SHORT TERM /REST OF TODAY/... CLEAR AND DRY DAY FOR CENTRAL NC. WILL UPDATE FORECAST DWPTS FOR THIS AFTERNOON DROPPING THEM SEVERAL DEGREES BASED UPON RUC SOUNDINGS AND NW FLOW. OTHERWISE FORECAST IS ON TRACK AND NO OTHER CHANGES ARE ANTICIPATED FOR THE MORNING UPDATE. && .PREV DISCUSSION... /ISSUED 245 AM EST SAT FEB 10 2007/ SHORT TERM /TODAY THROUGH SUNDAY NIGHT/... TODAY... WEAK S/W AND ASSOCIATED CLOUDINESS CURRENTLY MOVING THROUGH CWA WILL BE EAST OF AREA PRIOR TO DAYBREAK. THEN CLEARING SKIES. EXPECT SOME HIGH CLOUDS DURING THE AFTERNOON BUT MOSTLY SUNNY SKIES WILL PREVAIL. HIGH PRESSURE WILL CONTINUE TO BUILD SOUTHEAST OVER THE REGION. DEWPOINTS HAVE RECOVERED EARLY THIS MORNING FROM THE SUB-ZERO VALUES OF YESTERDAY. BUT SHOULD SEE DEWPOINTS PLUNGE TO SUB-ZERO VALUES AGAIN THIS AFTERNOON AS RE-ENFORCEMENT OF DRY AIR INTO REGION...ESPECIALLY NORTHERN TIER BUT NOT AS LOW AS YESTERDAY. WARMER TODAY WITH HIGHS RANGING FROM THE LOWER TO UPPER 40S...A FEW LOCATIONS SOUTHEAST SECTIONS MAY APPROACH THE 50 DEGREE MARK. TONIGHT... HIGH PRESSURE SETTLING OVERHEAD...CLEAR SKIES AND LIGHT WINDS WILL RESULT IN A COLD NIGHT. SOME TEENS ARE POSSIBLE ACROSS NORTHERN TIER. GENERAL RANGE OF 19-24 ACROSS THE CWA. SUNDAY AND SUNDAY NIGHT... HIGH PRESSURE MOVING OFFSHORE WITH RETURN FLOW SETTING UP OVER AREA. THUS CLOUDS AND MOISTURE WILL BE ON THE INCREASE. CONTINUED WARMING WITH HIGHS IN THE UPPER 40S TO LOWER 50S. LOWS GENERALLY 25 TO 30. LONG TERM /MONDAY THROUGH FRIDAY/... UNSETTLED WEATHER DEVELOPS DURING THIS PERIOD. THERE IS THE POTENTIAL FOR POSSIBLE P-TYPE ISSUES TOWARD MID WEEK BUT LOW CONFIDENCE AS CONSIDERABLE UNCERTAINTY AND MODELS INCONSISTENCIES. MONDAY WILL BE THE WARMEST OF THE WEEK AS SOUTHERLY FLOW PUMP WARM AIR INTO THE REGION. HIGHS WILL BE IN THE 50S TO NEAR 60 SOUTHEAST. THERE IS POTENTIAL FOR RAIN DEVELOPING MAINLY MONDAY AFTERNOON AS SOUTHERN STREAM WAVE HEADS TOWARD THE SOUTHEAST MID ATLC. TRENDS INDICATE PRECIP MOVING IN SLOWER. SO DONT EXPECT MUCH IN THE WAY OF RAIN BY MONDAY MORNING. STILL UNCERTAINTY REMAINS AS TO THE TRACK/STRENGTH OF THIS WAVE AND DEVELOPING SURFACE LOW. ALSO MODEL TRENDS HAVE BEEN QUITE VARIABLE. THE GFS TRENDS HAVE BEEN INCONSISTENT FROM RUN TO RUN...AS ONE RUN BRINGS SYSTEM FURTHER NORTH AND WARMER...NEXT RUN COLDER WITH SYSTEM FARTHER SOUTH. ALSO OF NOTE...NO STRONG HIGH AS HIGH CENTERED WELL TO THE NORTHWEST AND NO DRY AIR RIDGE. SO AT THIS POINT WILL CONTINUE CURRENT FORECAST TRENDS...RAIN MOVING IN BY MONDAY AFTERNOON WITH LIKELY POPS TUESDAY INTO TUESDAY EVENING. TOO MUCH UNCERTAINTY TO INCLUDE ANY P-TYPE TRENDS FOR TUESDAY NIGHT INTO WEDNESDAY AS DEPENDANT UPON TRACK/STRENGTH OF SURFACE LOW. ANY DEVIATION COULD MEAN THE DIFFERENCE AS TO WHETHER LIQUID OR FROZEN P-TYPE CONCERNS. ADDRESS ON LATER SHIFTS/SUBSEQUENT MODEL RUNS. A RETURN TO MUCH COLDER WEATHER BY THE END OF THE WEEK. AVIATION /05Z-24Z/... VFR CONDITIONS WILL CONTINUE. MINOR DISTURBANCES IN FAST WEST NORTHWEST FLOW ALOFT WILL RESULT IN OCCASIONAL BROKEN LAYERS AT OR ABOVE 8 THSD FT THROUGH DAYBREAK. OTHERWISE SURFACE HIGH PRESSURE AND A VERY DRY AIRMASS WILL CONTINUE TO DRIFT INTO THE REGION FROM THE UPPER MIDWEST THROUGH TONIGHT. -RFG/RHJ FIRE WEATHER... VERY DRY AIR MASS OVER THE REGION WILL RESULT IN VERY LOW RHS AGAIN TODAY ESPECIALLY ACROSS NORTHERN SECTIONS. POTENTIAL FOR RHS AT OR BELOW 15 PERCENT. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JO nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 1154 AM EST SAT FEB 10 2007 .SHORT TERM UPDATE/THIS AFTERNOON/... A SYSTEM MOVING SOUTH THROUGH EASTERN GREAT LAKES CAUSING SOME FLURRIES AND OR SNOW SHOWERS. ACCUMULATIONS INCH OR LESS THROUGH THE EARLY AFTERNOON. HIGHS 15 TO 20. && .AVIATION(12Z-12Z)... A WEAK SURFACE TROF WILL MOVE ACROSS NRN OH/NW PA THIS MORNING. EXPECT WIDESPREAD FLURRIES AND MVFR CIGS THIS MORNING BUT LITTLE TO NO ACCUMULATION. SNOW WILL BE A LITTLE HEAVIER IN THE SNOW BELT EAST OF CLEVELAND...BUT EVEN THERE SHOULD NOT SEE MUCH IN THE WAY OF ACCUMULATION. AGAIN AS WITH THE 06Z AFD RUC SEEMED TO HAVE THE BEST HANDLE ON THE CLOUDS. CLOUDS GRADUALLY CLEARING FROM THE WEST THIS AFTERNOON AS RIDGE OF HIGH PRESSURE OVER THE MIDDLE MISSISSIPPI VALLEY SHIFTS EAST. THINGS SHOULD REMAIN VFR OVERNIGHT. && .SHORT TERM /TODAY-MONDAY/... WEAK SFC TROF ACRS WRN LERI INTO NW OHIO WITH AN UPR LVL S/W MOVING THROUGH THE LOWER LAKES PROG TO MOV ACROSS THE AREA THIS MORNING. EXPECT CLOUDINESS WITH THESE FEATURES TO BECOME MORE WIDESPREAD OVER THE REGION THIS MORNING. EXPECT FLURRIES THIS MORNING MOST PLACES AS THESE FEATURES MOVE THROUGH. WILL CONTINUE WITH THE CHC/SCT LAKE EFFECT SNOW SHOWERS IN THE WESTERLY FLOW IN THE EXTREME NE THROUGHOUT THE DAY. VERY LIMITED MOISTURE AND WITH LAKE BEING MOSTLY ICE COVERE NOT EXPECTING ANY ACCUMULULATING OR LEAST LESS THAN INCH. SOME FLURRIES WILL LIKELY CONTINUE IN THE NE TONIGHT. HIGH PRESSURE BUILDS IN LATER TONIGHT MOVING THROUGH THE OHIO VALLEY LATE TONIGHT AND EARLY SUNDAY. BACKING WINDS SHOULD END ANY LAKE EFFECT FLURRIES/SNOW SHOWERS EARLY SUNDAY. WONT MAKE ANY CHANGES TO FORECAST FOR SUNDAY NIGHT AND MONDAY AT THIS TIME. STILL DIFFERENCE IN MODELS ON HOW FAST PCPN RETURN WITH NAM NOW HOLDING OFF UNTIL MONDAY WITH GFS SPREADING BACK IN SUNDAY NIGHT...FLIP FLOP FROM 12Z RUN. THE DRY AMS IN PLACE AND RIDGE JUST EXITING SUNDAY NIGHT WILL CONTINUE TO HOLD OFF THE PRCIP UNTIL MONDAY EXCEPT IN THE WEST. && && .LONG TERM /TUESDAY-FRIDAY/... NO MAJOR CHANGES TO THE LONG TERM PLANNED. PATTERN REMAINS QUITE COLD WITH BELOW NORMAL TEMPS CONTINUING. THE MODELS ARE IN FAIRLY GOOD AGREEMENT...BUT DO HAVE SOME ISSUES WITH THE TIMING OF THE TRUE ARCTIC AIRMASS MOVING IN BY WED. THE ECMWF HAS BEEN CONSISTENTLY FASTER WITH THIS FEATURE FOR THE PAST SEVERAL DAYS...WHILE THE GFS IS STARTING TO COME AROUND. IT LOOKS LIKE THE SOUTHERN STREAM SYSTEM WILL STAY FAR ENOUGH SOUTH AND EAST TO KEEP MOST OF THE SNOW OUT OF THE AREA. WITH THE INEVITABLE WEAK INVERTED TROUGH MOVING THRU THE AREA TUE THERE COULD BE SOME LIGHT SNOW MOVING THRU...BUT THE DRY AIR AND DOWNWARD MOTION FROM THE HIGH SHOULD BE ENOUGH TO GREATLY DIMINISH MOST PCPN. WILL DROP POPS TO LOW CHANCE FOR THE AREA ON TUE. NORTHERLY FLOW MAY ALLOW FOR A LAKE HURON FETCH...AND HAVE CONTINUED 30 POP FOR THE NORTH TUE NIGHT. ARCTIC AIR ONCE AGAIN MOVES INTO THE AREA WED-THU WITH 850MB TEMPS BELOW -20C PER GFS/ECMWF PROGS. FLOW EVENTUALLY BACKS TO THE NW WHICH SHOULD ALLOW FOR LES IN THE TRADITIONAL SNOWBELT. HOWEVER...WITH LAKE ERIE BEING MOSTLY ICE COVERED...WILL HAVE TO RELY ON LAKE HURON FOR MUCH OF THE HEAT FLUX AND MOISTURE. ALTHOUGH IT WILL LIKELY SNOW WITH COLD 850MB TEMPS...DO NOT THINK IT WILL BE A BIG EVENT DUE TO STRONG HIGH PRES AND ASSOCIATED DRY AIR/DOWNWARD MOTION. WILL CONTINUE WITH CHANCE WORDING IN THE SNOWBELT THRU FRIDAY WITH PERSISTENT NW FLOW. AS STATED ABOVE...TEMPS WILL CONTINUE BELOW NORMAL. SOME TIMING ISSUES WITH THE TRUE ARCTIC AIR...BUT WED/THU WILL LIKELY BE THE COLDEST DAYS OF THE EXTENDED WITH TEMPS LUCKY TO RISE OUT OF THE TEENS DURING THE DAY AND WILL STAY IN THE LOW SINGLE DIGITS AT NIGHT. MAY SEE SOME BELOW ZERO TEMPS AGAIN WED/THU. IN GENERAL...HAVE CUT A FEW DEGREES OFF OF GFS MOS GUIDANCE AND HPC EXTENDED GUIDANCE...ESPECIALLY AT NIGHT WITH SNOW COVER AND POTENTIAL FOR MOSTLY CLEAR SKIES. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. && $$ SHORT TERM...THOMPSON LONG TERM...MRD AVIATION...DJB oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 630 AM EST SAT FEB 10 2007 .AVIATION(12Z-12Z)... A WEAK SURFACE TROF WILL MOVE ACROSS NRN OH/NW PA THIS MORNING. EXPECT WIDESPREAD FLURRIES AND MVFR CIGS THIS MORNING BUT LITTLE TO NO ACCUMULATION. SNOW WILL BE A LITTLE HEAVIER IN THE SNOW BELT EAST OF CLEVELAND...BUT EVEN THERE SHOULD NOT SEE MUCH IN THE WAY OF ACCUMULATION. AGAIN AS WITH THE 06Z AFD RUC SEEMED TO HAVE THE BEST HANDLE ON THE CLOUDS. CLOUDS GRADUALLY CLEARING FROM THE WEST THIS AFTERNOON AS RIDGE OF HIGH PRESSURE OVER THE MIDDLE MISSISSIPPI VALLEY SHIFTS EAST. THINGS SHOULD REMAIN VFR OVERNIGHT. && .SHORT TERM /TODAY-MONDAY/... WEAK SFC TROF ACRS WRN LERI INTO NW OHIO WITH AN UPR LVL S/W MOVING THROUGH THE LOWER LAKES PROG TO MOV ACROSS THE AREA THIS MORNING. EXPECT CLOUDINESS WITH THESE FEATURES TO BECOME MORE WIDESPREAD OVER THE REGION THIS MORNING. EXPECT FLURRIES THIS MORNING MOST PLACES AS THESE FEATURES MOVE THROUGH. WILL CONTINUE WITH THE CHC/SCT LAKE EFFECT SNOW SHOWERS IN THE WESTERLY FLOW IN THE EXTREME NE THROUGHOUT THE DAY. VERY LIMITED MOISTURE AND WITH LAKE BEING MOSTLY ICE COVERE NOT EXPECTING ANY ACCUMULULATING OR LEAST LESS THAN INCH. SOME FLURRIES WILL LIKELY CONTINUE IN THE NE TONIGHT. HIGH PRESSURE BUILDS IN LATER TONIGHT MOVING THROUGH THE OHIO VALLEY LATE TONIGHT AND EARLY SUNDAY. BACKING WINDS SHOULD END ANY LAKE EFFECT FLURRIES/SNOW SHOWERS EARLY SUNDAY. WONT MAKE ANY CHANGES TO FORECAST FOR SUNDAY NIGHT AND MONDAY AT THIS TIME. STILL DIFFERENCE IN MODELS ON HOW FAST PCPN RETURN WITH NAM NOW HOLDING OFF UNTIL MONDAY WITH GFS SPREADING BACK IN SUNDAY NIGHT...FLIP FLOP FROM 12Z RUN. THE DRY AMS IN PLACE AND RIDGE JUST EXITING SUNDAY NIGHT WILL CONTINUE TO HOLD OFF THE PRCIP UNTIL MONDAY EXCEPT IN THE WEST. && && .LONG TERM /TUESDAY-FRIDAY/... NO MAJOR CHANGES TO THE LONG TERM PLANNED. PATTERN REMAINS QUITE COLD WITH BELOW NORMAL TEMPS CONTINUING. THE MODELS ARE IN FAIRLY GOOD AGREEMENT...BUT DO HAVE SOME ISSUES WITH THE TIMING OF THE TRUE ARCTIC AIRMASS MOVING IN BY WED. THE ECMWF HAS BEEN CONSISTENTLY FASTER WITH THIS FEATURE FOR THE PAST SEVERAL DAYS...WHILE THE GFS IS STARTING TO COME AROUND. IT LOOKS LIKE THE SOUTHERN STREAM SYSTEM WILL STAY FAR ENOUGH SOUTH AND EAST TO KEEP MOST OF THE SNOW OUT OF THE AREA. WITH THE INEVITABLE WEAK INVERTED TROUGH MOVING THRU THE AREA TUE THERE COULD BE SOME LIGHT SNOW MOVING THRU...BUT THE DRY AIR AND DOWNWARD MOTION FROM THE HIGH SHOULD BE ENOUGH TO GREATLY DIMINISH MOST PCPN. WILL DROP POPS TO LOW CHANCE FOR THE AREA ON TUE. NORTHERLY FLOW MAY ALLOW FOR A LAKE HURON FETCH...AND HAVE CONTINUED 30 POP FOR THE NORTH TUE NIGHT. ARCTIC AIR ONCE AGAIN MOVES INTO THE AREA WED-THU WITH 850MB TEMPS BELOW -20C PER GFS/ECMWF PROGS. FLOW EVENTUALLY BACKS TO THE NW WHICH SHOULD ALLOW FOR LES IN THE TRADITIONAL SNOWBELT. HOWEVER...WITH LAKE ERIE BEING MOSTLY ICE COVERED...WILL HAVE TO RELY ON LAKE HURON FOR MUCH OF THE HEAT FLUX AND MOISTURE. ALTHOUGH IT WILL LIKELY SNOW WITH COLD 850MB TEMPS...DO NOT THINK IT WILL BE A BIG EVENT DUE TO STRONG HIGH PRES AND ASSOCIATED DRY AIR/DOWNWARD MOTION. WILL CONTINUE WITH CHANCE WORDING IN THE SNOWBELT THRU FRIDAY WITH PERSISTENT NW FLOW. AS STATED ABOVE...TEMPS WILL CONTINUE BELOW NORMAL. SOME TIMING ISSUES WITH THE TRUE ARCTIC AIR...BUT WED/THU WILL LIKELY BE THE COLDEST DAYS OF THE EXTENDED WITH TEMPS LUCKY TO RISE OUT OF THE TEENS DURING THE DAY AND WILL STAY IN THE LOW SINGLE DIGITS AT NIGHT. MAY SEE SOME BELOW ZERO TEMPS AGAIN WED/THU. IN GENERAL...HAVE CUT A FEW DEGREES OFF OF GFS MOS GUIDANCE AND HPC EXTENDED GUIDANCE...ESPECIALLY AT NIGHT WITH SNOW COVER AND POTENTIAL FOR MOSTLY CLEAR SKIES. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. && $$ SHORT TERM...WCR LONG TERM...MRD AVIATION...DJB oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 300 AM EST SAT FEB 10 2007 .SHORT TERM /TODAY-MONDAY/... WEAK SFC TROF ACRS WRN LERI INTO NW OHIO WITH AN UPR LVL S/W MOVING THROUGH THE LOWER LAKES PROG TO MOV ACROSS THE AREA THIS MORNING. EXPECT CLOUDINESS WITH THESE FEATURES TO BECOME MORE WIDESPREAD OVER THE REGION THIS MORNING. EXPECT FLURRIES THIS MORNING MOST PLACES AS THESE FEATURES MOVE THROUGH. WILL CONTINUE WITH THE CHC/SCT LAKE EFFECT SNOW SHOWERS IN THE WESTERLY FLOW IN THE EXTREME NE THROUGHOUT THE DAY. VERY LIMITED MOISTURE AND WITH LAKE BEING MOSTLY ICE COVERE NOT EXPECTING ANY ACCUMULULATING OR LEAST LESS THAN INCH. SOME FLURRIES WILL LIKELY CONTINUE IN THE NE TONIGHT. HIGH PRESSURE BUILDS IN LATER TONIGHT MOVING THROUGH THE OHIO VALLEY LATE TONIGHT AND EARLY SUNDAY. BACKING WINDS SHOULD END ANY LAKE EFFECT FLURRIES/SNOW SHOWERS EARLY SUNDAY. WONT MAKE ANY CHANGES TO FORECAST FOR SUNDAY NIGHT AND MONDAY AT THIS TIME. STILL DIFFERENCE IN MODELS ON HOW FAST PCPN RETURN WITH NAM NOW HOLDING OFF UNTIL MONDAY WITH GFS SPREADING BACK IN SUNDAY NIGHT...FLIP FLOP FROM 12Z RUN. THE DRY AMS IN PLACE AND RIDGE JUST EXITING SUNDAY NIGHT WILL CONTINUE TO HOLD OFF THE PRCIP UNTIL MONDAY EXCEPT IN THE WEST. && && .LONG TERM /TUESDAY-FRIDAY/... NO MAJOR CHANGES TO THE LONG TERM PLANNED. PATTERN REMAINS QUITE COLD WITH BELOW NORMAL TEMPS CONTINUING. THE MODELS ARE IN FAIRLY GOOD AGREEMENT...BUT DO HAVE SOME ISSUES WITH THE TIMING OF THE TRUE ARCTIC AIRMASS MOVING IN BY WED. THE ECMWF HAS BEEN CONSISTENTLY FASTER WITH THIS FEATURE FOR THE PAST SEVERAL DAYS...WHILE THE GFS IS STARTING TO COME AROUND. IT LOOKS LIKE THE SOUTHERN STREAM SYSTEM WILL STAY FAR ENOUGH SOUTH AND EAST TO KEEP MOST OF THE SNOW OUT OF THE AREA. WITH THE INEVITABLE WEAK INVERTED TROUGH MOVING THRU THE AREA TUE THERE COULD BE SOME LIGHT SNOW MOVING THRU...BUT THE DRY AIR AND DOWNWARD MOTION FROM THE HIGH SHOULD BE ENOUGH TO GREATLY DIMINISH MOST PCPN. WILL DROP POPS TO LOW CHANCE FOR THE AREA ON TUE. NORTHERLY FLOW MAY ALLOW FOR A LAKE HURON FETCH...AND HAVE CONTINUED 30 POP FOR THE NORTH TUE NIGHT. ARCTIC AIR ONCE AGAIN MOVES INTO THE AREA WED-THU WITH 850MB TEMPS BELOW -20C PER GFS/ECMWF PROGS. FLOW EVENTUALLY BACKS TO THE NW WHICH SHOULD ALLOW FOR LES IN THE TRADITIONAL SNOWBELT. HOWEVER...WITH LAKE ERIE BEING MOSTLY ICE COVERED...WILL HAVE TO RELY ON LAKE HURON FOR MUCH OF THE HEAT FLUX AND MOISTURE. ALTHOUGH IT WILL LIKELY SNOW WITH COLD 850MB TEMPS...DO NOT THINK IT WILL BE A BIG EVENT DUE TO STRONG HIGH PRES AND ASSOCIATED DRY AIR/DOWNWARD MOTION. WILL CONTINUE WITH CHANCE WORDING IN THE SNOWBELT THRU FRIDAY WITH PERSISTENT NW FLOW. AS STATED ABOVE...TEMPS WILL CONTINUE BELOW NORMAL. SOME TIMING ISSUES WITH THE TRUE ARCTIC AIR...BUT WED/THU WILL LIKELY BE THE COLDEST DAYS OF THE EXTENDED WITH TEMPS LUCKY TO RISE OUT OF THE TEENS DURING THE DAY AND WILL STAY IN THE LOW SINGLE DIGITS AT NIGHT. MAY SEE SOME BELOW ZERO TEMPS AGAIN WED/THU. IN GENERAL...HAVE CUT A FEW DEGREES OFF OF GFS MOS GUIDANCE AND HPC EXTENDED GUIDANCE...ESPECIALLY AT NIGHT WITH SNOW COVER AND POTENTIAL FOR MOSTLY CLEAR SKIES. && .AVIATION(06Z-06Z)... A WEAK SURFACE TROF WILL AFFECT THE EASTERN PORTION OF THE FORECAST AREA BY 12Z. PLENTY OF CLOUDS OVER MICHIGAN SEEMED TO BE HEADED TO THE FORECAST AREA. THE MODELS SEEM TO BE HAVING A TOUGH TIME HANDLING THIS. THE GFS AND NAM TRY TO BRING THE CLOUDS IN FOR A SHORT TIME OVERNIGHT AND THEN LIFT THEM OUT SATURDAY MORNING AND THEN BRING THEM BACK IN SATURDAY AFTERNOON. THE 03Z RUC SEEMS TO HAVE A HANDLE ON THINGS BRINING IN CEILINGS 3000 TO 3500 AND KEEPING THEM MUCH OF SATURDAY DURING THE DAYLIGHT HOURS AND THEN AS THE RIDGE GETS CLOSER AND THE FLOW WESTERLY...DRYING OUT. BECAUSE OF THE NORTHWEST FLOW...I AM GOING WITH THE RUC AND BRING THE CLOUDS IN AND KEEP THEM IN. WATCHING PLENTY OF FLURRIES OVER MICHIGAN...MOST OF THE VISIBILITIES ARE UNRESTRICTED...WILL GO WITH THAT EXCEPT AT ERI AND YNG. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. && $$ SHORT TERM...WCR LONG TERM...MRD AVIATION...KIELTYKA oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 1146 PM EST FRI FEB 9 2007 .AVIATION(06Z-06Z)... A WEAK SURFACE TROF WILL AFFECT THE EASTERN PORTION OF THE FORECAST AREA BY 12Z. PLENTY OF CLOUDS OVER MICHIGAN SEEMED TO BE HEADED TO THE FORECAST AREA. THE MODELS SEEM TO BE HAVING A TOUGH TIME HANDLING THIS. THE GFS AND NAM TRY TO BRING THE CLOUDS IN FOR A SHORT TIME OVERNIGHT AND THEN LIFT THEM OUT SATURDAY MORNING AND THEN BRING THEM BACK IN SATURDAY AFTERNOON. THE 03Z RUC SEEMS TO HAVE A HANDLE ON THINGS BRINING IN CEILINGS 3000 TO 3500 AND KEEPING THEM MUCH OF SATURDAY DURING THE DAYLIGHT HOURS AND THEN AS THE RIDGE GETS CLOSER AND THE FLOW WESTERLY...DRYING OUT. BECAUSE OF THE NORTHWEST FLOW...I AM GOING WITH THE RUC AND BRING THE CLOUDS IN AND KEEP THEM IN. WATCHING PLENTY OF FLURRIES OVER MICHIGAN...MOST OF THE VISIBILITIES ARE UNRESTRICTED...WILL GO WITH THAT EXCEPT AT ERI AND YNG. && .SHORT TERM /TONIGHT/... QUESTION FOR REST OF TNGT IS WHETHER OR NOT SFC TROF WL BE ABLE TO CLEANLY PUSH SE ACRS LERI INTO NERN OH AND NW PA. FOR WK TROFS LIKE THIS THERE IS A TENDENCY FOR THE MODELS TO PUSH THE TROF THRU BUT IN FACT THE TROF OFTEN LINGERS BACK OVER THE LAKES CLOSER TO THE THERMAL FIELD INDUCING THE TROF. FOR THE OVERNIGHT WL TRIM BACK SOME ON THE SNOWFALL TO MAKE THE FCST MORE OPTIMISTIC AND BACK TIMING OF ACCUMULATING SN FOR THE SNOWBELT TIL TWD DAYBREAK. WL STAY WITH FCST LOW TEMPS WHICH SEEM TO BE A GOOD A GUESS AS ANY. WNDS ON AVG SHUD STAY UNDER 10 MPH DURG THE COLDER LATE NITE/EARLY MORN HRS SO WL CONT TO STAY AWAY FM ANY WIND CHILL ADVISORIES. BESIDES THE WND CHILL ADVSRY HAS BEEN BEATEN TO DEATH OVR THE PAST WK ANYWAY AND TOMORROW MORN IS NOT A SCHOOL DAY NOR A WORK DAY FOR MOST PEOPLE. && .SHORT TERM /TONIGHT-MONDAY/... HIGH PRES RIDGING CONTINUES ACROSS THE AREA. A SHORT WAVE OVER THE NORTHERN PLAINS/WESTERN GREAT LAKES WILL MOVE SOUTH AND EAST OVERNIGHT...AND PASS OVER THE AREA SAT MORNING. NOT MUCH WEATHER ASSOCIATED WITH THIS SYSTEM...OTHER THAN SOME MID-HIGH CLOUDS. AHEAD OF THE SYSTEM THIS EVENING...THE SURFACE WINDS WILL BACK TO W-SW LIMITING ANY LES TO THE EXTREME LAKESHORE OF NW PA. BEHIND THE SHORT WAVE AND ASSOCIATED SFC REFLECTION...THE BOUNDARY LAYER WINDS WILL TURN W-NW WHICH SHOULD ALLOW ANY LES TO MOVE INLAND AND INCREASE DUE TO BETTER SYNOPTIC SUPPORT FROM THE SHORT WAVE. WILL GO WITH LIKELY POPS IN THE NW PA SNOWBELT...BUT ONLY LIMIT ACCUMS TO 1-2 INCHES DUE TO THE LOSS OF HEAT FLUX FROM THE LAKE DUE TO IT BEING MOSTLY ICE COVERED. THE ARCTIC HIGH SLOWLY BUILDS INTO THE AREA FOR THE WEEKEND. W-NW FLOW WILL KEEP AT LEAST SMALL CHANCE OF LES IN THE SNOWBELT THRU SUNDAY...BUT ONCE AGAIN THE CHANCES WILL BE DIMINISHED DUE TO ICE COVER. AS THE HIGH BUILDS OVERHEAD ON SAT NIGHT/SUN MORNING EXPECT SKIES TO CLEAR OUT ACROSS THE ENTIRE AREA AWAY FROM THE SNOWBELT. WINDS WILL SLOWLY TURN SW ON SUNDAY AS THE HIGH BUILDS EAST AND WARM ADVECTION SETS UP. THIS SHOULD DIMINISH ALL CHANCES OF SNOW UNTIL SUNDAY NIGHT WHEN THE NEXT FRONT APPROACHES. THE MODELS DIFFER ON HOW FAST THE PCPN MOVES INTO THE AREA...WITH THE NAM BRINGING PCPN IN SUN NIGHT AND THE GFS HOLDING OFF UNTIL MON AFTN. WITH HIGH PRES RIDGING ACROSS THE AREA SUN NIGHT...I WOULD EXPECT THAT THE PCPN WILL LIKELY HOLD OFF ESPECIALLY WITH THE DRY AIRMASS ALREADY IN PLACE. A DECENT BAROCLINIC ZONE SETS UP JUST SOUTH OF THE AREA ON MONDAY INTO MONDAY NIGHT...BUT IT LOOKS LIKE THE BEST PCPN WILL ALSO STAY SOUTH OF THE AREA WHERE THE BETTER LIFT OCCURS. COULD SEE AN INCH OR TWO OF LIGHT SYNOPTIC SNOW MON/MON NIGHT...WITH PERHAPS SOME WEAK LAKE ENHANCEMENT IN THE NE FLOW MON NIGHT...BUT WITH THE STRONG RIDGING MOVING IN IT DOES NOT LOOK LIKELY. TEMPS WILL REMAIN BELOW NORMAL THRU THE WKND. IT WILL CONTINUE TO BE QUITE COLD AGAIN TONIGHT WITH LOWS IN THE ZERO TO 5 ABOVE RANGE WITH WINDS 5-10 MPH. EXPECT WIND CHILL VALUES AROUND -10F...OR JUST BELOW ADVY CRITERIA OF -15F. ALTHOUGH MOS GUIDANCE ALLOWS TEMPS TO RISE INTO THE MID-UPR 20S ON SUNDAY...WITH THE SNOW COVER AND INCREASING MID CLOUDS HAVE OPTED TO GO LOWER THAN GUIDANCE. SKIES SHOULD ALSO BE RELATIVELY CLEAR SAT NIGHT SO EXPECT TEMPS TO ALSO BE A CATEGORY OR TWO LOWER THAN GUIDANCE. && .LONG TERM /TUESDAY-FRIDAY/... NO MAJOR CHANGES TO THE LONG TERM PLANNED. PATTERN REMAINS QUITE COLD WITH BELOW NORMAL TEMPS CONTINUING. THE MODELS ARE IN FAIRLY GOOD AGREEMENT...BUT DO HAVE SOME ISSUES WITH THE TIMING OF THE TRUE ARCTIC AIRMASS MOVING IN BY WED. THE ECMWF HAS BEEN CONSISTENTLY FASTER WITH THIS FEATURE FOR THE PAST SEVERAL DAYS...WHILE THE GFS IS STARTING TO COME AROUND. IT LOOKS LIKE THE SOUTHERN STREAM SYSTEM WILL STAY FAR ENOUGH SOUTH AND EAST TO KEEP MOST OF THE SNOW OUT OF THE AREA. WITH THE INEVITABLE WEAK INVERTED TROUGH MOVING THRU THE AREA TUE THERE COULD BE SOME LIGHT SNOW MOVING THRU...BUT THE DRY AIR AND DOWNWARD MOTION FROM THE HIGH SHOULD BE ENOUGH TO GREATLY DIMINISH MOST PCPN. WILL DROP POPS TO LOW CHANCE FOR THE AREA ON TUE. NORTHERLY FLOW MAY ALLOW FOR A LAKE HURON FETCH...AND HAVE CONTINUED 30 POP FOR THE NORTH TUE NIGHT. ARCTIC AIR ONCE AGAIN MOVES INTO THE AREA WED-THU WITH 850MB TEMPS BELOW -20C PER GFS/ECMWF PROGS. FLOW EVENTUALLY BACKS TO THE NW WHICH SHOULD ALLOW FOR LES IN THE TRADITIONAL SNOWBELT. HOWEVER...WITH LAKE ERIE BEING MOSTLY ICE COVERED...WILL HAVE TO RELY ON LAKE HURON FOR MUCH OF THE HEAT FLUX AND MOISTURE. ALTHOUGH IT WILL LIKELY SNOW WITH COLD 850MB TEMPS...DO NOT THINK IT WILL BE A BIG EVENT DUE TO STRONG HIGH PRES AND ASSOCIATED DRY AIR/DOWNWARD MOTION. WILL CONTINUE WITH CHANCE WORDING IN THE SNOWBELT THRU FRIDAY WITH PERSISTENT NW FLOW. AS STATED ABOVE...TEMPS WILL CONTINUE BELOW NORMAL. SOME TIMING ISSUES WITH THE TRUE ARCTIC AIR...BUT WED/THU WILL LIKELY BE THE COLDEST DAYS OF THE EXTENDED WITH TEMPS LUCKY TO RISE OUT OF THE TEENS DURING THE DAY AND WILL STAY IN THE LOW SINGLE DIGITS AT NIGHT. MAY SEE SOME BELOW ZERO TEMPS AGAIN WED/THU. IN GENERAL...HAVE CUT A FEW DEGREES OFF OF GFS MOS GUIDANCE AND HPC EXTENDED GUIDANCE...ESPECIALLY AT NIGHT WITH SNOW COVER AND POTENTIAL FOR MOSTLY CLEAR SKIES. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. && $$ SHORT TERM...MRD/ADAMS LONG TERM...MRD AVIATION...KIELTYKA oh AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1137 AM CST SAT FEB 10 2007 .AVIATION... NOT A CLEAR CUT CIG/FR FCST FOR N TX TAFS...BUT COORD WITH CWSU HAS BEEN INVALUABLE. PER RUC BL AND SOUNDING TRENDS...AND SATL...HAVE DECIDED TO KEEP VFR CIGS BTWN 035-040 THRU AT LEAST 21-22Z WHICH WILL AFFECT AIRPORT ACCEPTANCE RATES FOR LANDINGS. SFC FLO STILL N/NE MOST AREAS WHICH SHOULD KEEP CIGS IN DFW AREA TAFS...AND SLOWLY FILL IN AT WACO BY 20Z. MAY BE OPTIMISTIC ON SCT/HI VFR CIG CONDS AFTR 00Z...BUT WILL INDICATE THAT FOR NOW PER RUC PROGS...AS FLO VEER SELY...THEN SLY BY 18Z/AFTR ON SUNDAY...WITH MVFR CONDS RETURNING JUST BEFORE 12Z SUN AND LINGERING THRU 18Z. && .PREV DISCUSSION... /ISSUED 959 AM CST SAT FEB 10 2007/ UPDATE... MADE ONLY A FEW CHANGES TO AFTERNOON CLOUD COVER IN THE SOUTH...AND REMOVED MENTION OF FOG THIS MORNING. OTHERWISE NO FURTHER CHANGES AT THIS TIME. 42 AVIATION... 52227 AM CST... VFR CONDITIONS LIKELY TO PREVAIL THROUGH EARLY SUNDAY MORNING WITH OVC SKIES LIKELY BREAKING UP A BIT DURING THE DAY. THERE MAY BE A FEW HOURS WITH NO CIGS BUT IMPOSSIBLE TO TIME. FLOW GOES BACK SOUTHEAST THIS AFTN/EVE AND AS LOWER LEVELS SATURATE OVERNIGHT IT LOOKS LIKE MVFR CIGS WILL RETURN BEFORE SUNRISE SUNDAY. 84 DISCUSSION... 410 AM MOSTLY CLOUDY AND COOL CONDITIONS WILL PREVAIL ACROSS NORTH TEXAS TODAY AS THE COLD AIRMASS REMAINS IN PLACE ACROSS THE REGION. AS A LEE SIDE TROUGH DEVELOPS AND THE SURFACE RIDGE MOVES OFF TO THE EAST...WE WILL SEE THE LOW LEVEL WINDS BECOME SOUTHEAST TONIGHT... AND SOUTH SOUTHEASTERLY ON SUNDAY. WE WILL THEN SEE MODERATING TEMPERATURES AND INCREASED LOW LEVEL MOISTURE ON SUNDAY AND MONDAY. THERE WILL BE A CHANCE OF RAIN SUNDAY AFTERNOON ACROSS THE EAST...AND AREAWIDE SUNDAY NIGHT. BY MONDAY...WE WILL SEE A CHANCE OF THUNDERSTORMS AREAWIDE AS A SHORTWAVE APPROACHES. GIVEN THE EXPECTED LAPSE RATES AND SHEAR...THERE WILL BE THE POTENTIAL FOR SEVERE THUNDERSTORMS ACROSS THE EASTERN PART OF THE FORECAST AREA MONDAY AFTERNOON AND EVENING. A STRONG COLD FRONT IS EXPECTED TO ENTER THE NORTHWESTERN PART OF NORTH TEXAS LATE MONDAY AFTERNOON AND THROUGH THE SOUTHEAST SECTIONS AFTER MIDNIGHT. WE WILL SEE COLDER TEMPERATURES FOR THE REST OF THE WEEK. AS ANOTHER SHORTWAVE APPROACHES WEDNESDAY...WE WILL SEE PRECIPITATION CHANCE RETURN. FORECAST TEMPERATURE PROFILES INDICATE THAT WE HAVE A CHANCE OF A WINTRY MIX OF PRECIPITATION WEDNESDAY AND WEDNESDAY NIGHT WITH THE PRECIPITATION ENDING EARLY THURSDAY MORNING. #58 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 47 38 56 56 69 / 10 10 10 40 50 WACO, TX 49 41 58 58 70 / 10 10 20 40 50 PARIS, TX 48 34 49 49 66 / 10 10 10 60 60 DENTON, TX 47 38 55 55 70 / 10 10 10 40 40 MCKINNEY, TX 46 36 53 53 67 / 10 10 10 40 50 DALLAS, TX 48 40 56 56 70 / 10 10 10 40 50 TERRELL, TX 47 38 54 54 69 / 10 0 10 50 60 CORSICANA, TX 48 38 56 56 69 / 10 10 20 50 60 TEMPLE, TX 50 42 57 57 71 / 10 10 20 40 50 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 42/58/05 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 926 AM CST SAT FEB 10 2007 .UPDATE...ISENTROPIC LIFT WL CONTRIBUTE TO STRATIFORM RAIN TDA NOTWITHSTANDING THE UPPER DISTURBANCE MOVG ACRS DEEP SOUTH TX. CURRENT POPS REASONABLE. BASED ON OUTPUT FROM THE RUC...EXPECT SFC WIND TO FALL BELOW SCA CRITERION OVR THE COASTAL WATERS BY 21Z. SEA HGTS SHOULD REMAIN BELOW SCA CRITERION. && .CRP WATCHES/WARNINGS/ADVISORIES...TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR COASTAL WATERS BAFFIN BAY TO PORT ARANSAS OUT 20 NM-COASTAL WATERS PORT ARANSAS TO MATAGORDA SHIP CHANNEL OUT 20 NM-WATERS BAFFIN BAY TO PORT ARANSAS 20 TO 60 NM-WATERS PORT ARANSAS TO MATAGORDA SHIP CHANNEL 20 TO 60 NM. && $$ SHORT TERM...87 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WA 945 PM PST SAT FEB 10 2007 .SYNOPSIS...ANOTHER WEATHER DISTURBANCE WILL MOVE THROUGH THE PACIFIC NORTHWEST TONIGHT AND TOMORROW. RAIN AND MOUNTAIN SNOW WILL ACCOMPANY THE PASSAGE OF THIS DISTURBANCE. && .DISCUSSION... A WARM FRONT IS CURRENTLY MOVING THROUGH THE COLUMBIA BASIN AND HEADING NORTHEAST ACROSS THE FORECAST AREA. KOTX RADAR IS SHOWING A BAND OF PRECIPITATION FROM NEAR CHELAN SOUTHEAST TO NEAR PULLMAN. THE PRECIPITATION APPEARS TO BE LINING UP WITH THE ISENTROPIC UPGLIDE ALONG THE 285-295K. THE RUC40/00Z GFS SEEM TO HAVE HAD THE BEST HANDLE ON THE TIMING OF THE PRECIPITATION. THE 00Z NAM IS ABOUT 3 HOURS TO SLOW. POPS HAVE ALREADY BEEN BUMPED UP ACROSS THE FORECAST AREA AND DO NOT SEE ANY NEED TO UPDATE ANY FURTHER. REPORTS OF A QUICK INCH OF SNOW WAS REPORTED IN THE KLICKITAT VALLEY EARLIER THIS EVENING ABOVE 2500 FEET. THIS IS ALREADY COVERED IN THE FORECAST. LOCALIZED POCKETS OF FREEZING RAIN ARE POSSIBLE OVERNIGHT IN THE LOWER VALLEYS NORTH OF A SPOKANE-WENATCHEE LINE. AT 05Z SOME OF THE NORTHERN VALLEYS HAVE DIPPED BELOW FREEZING...HOWEVER CONFIDENCE REMAINS LOW THAT ANY APPRECIABLE AMOUNTS WILL BE SEEN BEFORE THE TEMPERATURES INCREASE BACK ABOVE FREEZING. /TOBIN && .AVIATION... KGEG-KCOE CORRIDOR AND THE VALLEYS TO THE NORTH OF THAT LINE WILL SEE IFR OR LOWER CONDITIONS THROUGH 07-09Z OR SO FOR VSBY/CIGS. OTHERWISE AN APPROACHING WARM FRONT WILL ALLOW A LITTLE BETTER VERTICAL MIXING FOR CONDITIONS IMPROVING VFR-MVFR OVERNIGHT. A BREAK IN THE STABLE PRECIPITATION AFTER 11Z WILL ALMOST CERTAINLY ALLOW CONDITIONS TO DETERIORATE EARLY THIS MORNING THROUGH 15Z. SHOWERS DEVELOPING WITH AN APPROACHING TROUGH THIS AFTERNOON WILL AGAIN ALLOW CONDITIONS TO CLIMB TO VFR-MVFR. /TOBIN && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 33 39 30 38 30 41 / 80 80 30 20 20 10 COEUR D`ALENE 33 39 30 38 30 41 / 70 90 50 30 20 10 PULLMAN 36 41 32 40 32 43 / 80 70 40 20 20 20 LEWISTON 38 45 35 45 33 46 / 80 60 40 20 20 10 COLVILLE 31 37 32 40 29 40 / 60 80 50 30 20 10 SANDPOINT 31 38 27 36 28 38 / 60 90 60 40 20 10 KELLOGG 32 41 31 39 30 41 / 60 90 60 40 30 10 MOSES LAKE 34 43 31 44 32 44 / 70 50 20 20 20 20 WENATCHEE 35 44 31 42 32 43 / 70 60 20 30 20 20 OMAK 32 41 29 39 28 42 / 70 70 30 20 20 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...NONE. WA...NONE. && $$ wa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 1020 AM CST SUN FEB 11 2007 .UPDATE... LATEST WATER VAPOR SATELLITE IMAGERY INDICATING WEAK UPPER LEVEL DISTURBANCE OVER WESTERN WISCONSIN. LATEST 16Z SURFACE METARS ACROSS FORECAST AREA INDICATING SNOW FLURRIES. 15Z LAPS/RUC SOUNDINGS INDICATE ANY PRECIPITATION THIS MORNING WILL BE ALL SNOW ACROSS FORECAST AREA. 12Z RUC FORECAST SOUNDINGS DO INDICATE ALL SNOW ACROSS PORTIONS OF NORTH CENTRAL WISCONSIN INTO THIS AFTERNOON. FOR THE REST OF THE FORECAST AREA...RUC FORECAST SOUNDINGS INDICATE LOSS OF ICE CRYSTALS THIS AFTERNOON AND THIS WILL ALLOW FOR PATCHY FREEZING DRIZZLE OR POSSIBLY FLURRIES. HAVE UPDATED TODAYS FORECAST FOR THESE TRENDS. && DTJ .PREV DISCUSSION... /ISSUED 352 AM CST SUN FEB 11 2007/ .SHORT TERM...THROUGH TUESDAY NIGHT FOCUS IN THE SHORT TERM ARE PLENTY...CHANCES OF FREEZING DRIZZLE TODAY...SNOW CHANCES/ACCUMULATIONS TONIGHT...AND THEN LARGE WINTER STORM MONDAY AND TUESDAY. WITH HPC NOTING NAM-WRF INITIALIZATION ERRORS IN NRN STREAM...HAVE SIDED THE FORECAST STRONGLY IN GFS/SREF COURT...WITH THESE SOLUTIONS AS WELL AS HI-RES CANADIAN GIVING A RATHER STRONG CONSENSUS THROUGH THE FIRST 48-60 HOURS. FIRST THING WE NEED TO ADDRESS IS THE FREEZING DRIZZLE POSSIBILITIES TODAY IN STRONG LOW LEVEL WARM ADVECTION REGIME AHEAD OF LOW AMPLITUDE WAVE TO MOVE THROUGH THE AREA THIS EVENING. AREA PROFILERS AND SURFACE OBSERVATIONS SHOWING RAPIDLY EXPANDING IFR CEILING/VISIBILITY DECK IN SWRN MN/NWRN IA MOVING EAST ON WESTERLY 925MB WINDS ON WOOD LAKE PROFILER. HAVE SEEN CEILINGS/VISIBILITIES TO OUR WEST LOWER QUICKLY...WITH WFO DMX NOTING SOME ICING OCCURRING IN NRN IA WHERE VSBYS DOWN TO 2SM AND BELOW. LATEST RUC-WRF SHOWING THIS LOW LEVEL MOISTURE SURGING INTO CWA THIS MORNING...AND DEEPENING INTO THE AFTERNOON. PERUSING BUFR SOUNDINGS ACROSS THE CWA GIVES MIXED RESULTS...AS TEMPERATURES VERY CLOSE TO HIGHER PROBABILITIES OF ICE INTRODUCTION AT THE TOP OF THE CLOUD LAYER /-10C/. ALSO OF CONCERN...IS TRANSIENT MID CLOUDS WHICH MAY SEED LOWER LEVEL DECKS AT TIMES THROUGH DAY. ALSO...LIFT IN THE WARM ADVECTION/ISENTROPIC CHARTS NOT ALL THAT IMPRESSIVE IN/ON TOP OF THE SATURATED LAYER...SO I DIDN/T GO TOO BULLISH ON THIS. STILL...WITH UPSTREAM SITES REPORTING SOME ISOLD -FZDZ...AND ALSO SOME VERY LIGHT SNOW/FLURRIES...I CARRIED THIS SCENARIO THROUGH MUCH OF THE DAY ACROSS CWA AS THE MOISTURE CONTINUES TO STREAM INTO THE AREA AS THE DAY WEARS ON. DON/T THINK IT WILL BE HEAVY OR WIDESPREAD ENOUGH TO WARRANT POPS THIS MORNING...BUT AS LARGE SCALE ASCENT /QG FORCING AND HEIGHT FALLS/ INCREASES THROUGH THE AFTERNOON AHEAD OF THE WAVE...COULD SEE A SOME MORE ORGANIZED AREAS BY LATER IN THE AFTERNOON...THUS LOWER POPS IN THE AFTN. NEXT UP IS THE WAVE FOR TONIGHT...MAINLY THIS EVENING. FORCING SIGNALS DRASTICALLY ON THE UPTICK IN THE LAST COUPLE OF RUNS OF DETERMINISTIC WRF AND GFS. THIS WAVE MOVING ACROSS ROCKIES AS WE SPEAK...AND HAS SOME DEEPER PACIFIC MOISTURE TO TAP...WITH AFOREMENTIONED SURGE OF LOW LEVEL MOISTURE AROUND BACKSIDE OF DEPARTING HIGH. WEAK/MOD BUT DEEP Q/G SIGNAL CROSSES SRN 2/3RD OF ARX CWA THIS EVENING AMIDST DEEP SATURATION. ISENTROPIC WORK /280-290K/ VERY SUPPORTIVE OF STRONG LIFT OVER THE SRN CWA. LATEST 11.06Z NAM-WRF NOW PUMPING OUT 0.30 INCHES OF LIQUID ACROSS SRN 2 TIERS OF COUNTIES...AND 11.00Z GFS NOT FAR BEHIND. BOTH 21Z AND 03Z SREF SHOW INCREASING PROBABILITIES...WITH 03Z SREF MEAN INDICATING 2 INCH PLUS OF SNOW IN GRANT COUNTY ALONG IL/WISC BORDER. THINK THIS SUPPORTS AT LEAST HIGH END LIKELY POPS RIGHT NOW AND SHOULD BE MOVED CATEGORICAL OVER SRN 1/2 OF CWA WITH NEXT ISSUANCE. FRONTOGENESIS IS STRONG ACROSS SRN 2 TIERS OF ARX CWA...AND EVEN CONCERNED ABOUT ANOTHER FRONTOGENETICAL BAND /800MB/ FURTHER NORTH OVER RST TO LSE LINE WHICH MAY BRING ACCUMS FURTHER NORTH FOR A TIME. STILL...ANTICIPATE THE LONGEST DURATION/STRONG FORCING ACROSS ALL OF NERN IA INTO SWRN WI...WHERE I AM RUNNING 2.0-3.5 INCHES OF ACCUMULATION. GIVEN STRONG CONSISTENT SIGNALS IN SREF/GFS/NAM WRF...AND ADDITIONAL SUPPORT IN SPC 5KM WRF AND HI RES CANADIAN...WOULD NOT BE AT ALL SURPRISED IF WE NEED TO MOVE TO AN ADVISORY FOR THE SRN 2 TIERS OF COUNTIES FOR 3-4 OR 3-5 INCHES OF SNOW. COBB DATA INDICATING SNOW-WATER RATIOS A LITTLE LESS THAN RECENTLY SEEN...DUE TO INFLUX OF WARMER AIR...MAINLY 11-13:1. NRN FRINGE OF SNOW WILL BE TOUGH /I-90 CORRIDOR/...AND THIS AREA COULD SEE ANYWHERE FROM A DUSTING TO 2 INCHES GIVEN WHAT SHOULD BE A TIGHT NRN FRINGE TO THE SNOW. FINALLY...LARGE WRN TROUGH MOVES INTO THE CNTL CONUS MONDAY AND GENS UP SIGNIFICANT/DEEPENING LOW PRESSURE OFF TO OUR SOUTH. NAM IS MUCH MORE NLY THAN ANY OTHER DETERMINISTIC RUN...THUS I AM IGNORING THE DECENT ACCUMULATIONS IT SENDS OUR WAY MONDAY NIGHT/TUES. THE SREF MEANS/PROBABILITIES AND GEFS PROBABILITIES DO NOT SUPPORT THIS PCPN THIS FAR NORTH INTO THE DRY NELY FLOW INTO THE SRN PLAINS LOW. I DID KEEP THE POPS IN THE FAR SOUTH FOR WHAT WILL BE A CLOSE CALL AS THE NRN FRINGE OF THE DEFORMATION/ISENTROPIC LIFT BRUSHES BY IN THE I-80/HWY 30 CORRIDORS. THIS WILL NEED TO BE WATCHED OVER THE NEXT 24 HOURS...BUT AS OF NOW...AGREEMENT IN ECMWF/GEFS/GFS SEEMS RATHER STRONG THAT THIS SYSTEM WILL PASS TO OUR SOUTH. WILL NEED TO WATCH WINDS ON MONDAY NIGHT/TUES FOR BLOWING SNOW OVER OPEN AREAS OF NERN IA WITH WHAT FALLS THIS EVENING. .LONG TERM...WEDNESDAY THROUGH SATURDAY PATTERN RE-AMPLIFICATION SEEMS IN THE CARDS IN THE WAKE OF THE STRONG SYSTEM TRAVERSING THE CNTL-ERN CONUS MON-WED. NEW 11.00Z GEFS MEAN AND ECMWF OPERATIONAL RUNS SHOWING HIGH AMPLITUDE WRN RIDGE/ERN TROUGH WITH ARX CWA IN STRONG NWLY FLOW. ECMWF SHOWS RATHER STRONG SHORTWAVE DIVING THROUGH THIS FLOW FRI/SAT SO THIS WILL HAVE TO BE WATCHED FOR SNOW CHANCES. OTHERWISE...TEMPERATURES STARTING OUT VERY COOL ON WEDNESDAY AS LOBE OF ARCTIC AIR MOVES THROUGH...THEN MODERATION AS PROXIMITY OF PACIFIC AIRMASS ALLOWS SOME WARM ADVECTION AHEAD OF THAT FRI/SAT WAVE. SHOULD SEE TEMPERATURES MODERATE BACK CLOSER TO NORMAL FOR THE FIRST TIME IN WEEKS...THOUGH LIKELY TO STAY JUST BELOW NORMAL GIVEN LOCATION OF RIDGE AXIS AND NWLY FLOW. MAY BE ANOTHER BRIEF DUMP OF ARCTIC AIR BEHIND THE WEEKEND SHORTWAVE TOO. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ BINAU wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 352 AM CST SUN FEB 11 2007 .SHORT TERM...THROUGH TUESDAY NIGHT FOCUS IN THE SHORT TERM ARE PLENTY...CHANCES OF FREEZING DRIZZLE TODAY...SNOW CHANCES/ACCUMULATIONS TONIGHT...AND THEN LARGE WINTER STORM MONDAY AND TUESDAY. WITH HPC NOTING NAM-WRF INITIALIZATION ERRORS IN NRN STREAM...HAVE SIDED THE FORECAST STRONGLY IN GFS/SREF COURT...WITH THESE SOLUTIONS AS WELL AS HI-RES CANADIAN GIVING A RATHER STRONG CONSENSUS THROUGH THE FIRST 48-60 HOURS. FIRST THING WE NEED TO ADDRESS IS THE FREEZING DRIZZLE POSSIBILITIES TODAY IN STRONG LOW LEVEL WARM ADVECTION REGIME AHEAD OF LOW AMPLITUDE WAVE TO MOVE THROUGH THE AREA THIS EVENING. AREA PROFILERS AND SURFACE OBSERVATIONS SHOWING RAPIDLY EXPANDING IFR CEILING/VISIBILITY DECK IN SWRN MN/NWRN IA MOVING EAST ON WESTERLY 925MB WINDS ON WOOD LAKE PROFILER. HAVE SEEN CEILINGS/VISIBILITIES TO OUR WEST LOWER QUICKLY...WITH WFO DMX NOTING SOME ICING OCCURRING IN NRN IA WHERE VSBYS DOWN TO 2SM AND BELOW. LATEST RUC-WRF SHOWING THIS LOW LEVEL MOISTURE SURGING INTO CWA THIS MORNING...AND DEEPENING INTO THE AFTERNOON. PERUSING BUFR SOUNDINGS ACROSS THE CWA GIVES MIXED RESULTS...AS TEMPERATURES VERY CLOSE TO HIGHER PROBABILITIES OF ICE INTRODUCTION AT THE TOP OF THE CLOUD LAYER /-10C/. ALSO OF CONCERN...IS TRANSIENT MID CLOUDS WHICH MAY SEED LOWER LEVEL DECKS AT TIMES THROUGH DAY. ALSO...LIFT IN THE WARM ADVECTION/ISENTROPIC CHARTS NOT ALL THAT IMPRESSIVE IN/ON TOP OF THE SATURATED LAYER...SO I DIDN/T GO TOO BULLISH ON THIS. STILL...WITH UPSTREAM SITES REPORTING SOME ISOLD -FZDZ...AND ALSO SOME VERY LIGHT SNOW/FLURRIES...I CARRIED THIS SCENARIO THROUGH MUCH OF THE DAY ACROSS CWA AS THE MOISTURE CONTINUES TO STREAM INTO THE AREA AS THE DAY WEARS ON. DON/T THINK IT WILL BE HEAVY OR WIDESPREAD ENOUGH TO WARRANT POPS THIS MORNING...BUT AS LARGE SCALE ASCENT /QG FORCING AND HEIGHT FALLS/ INCREASES THROUGH THE AFTERNOON AHEAD OF THE WAVE...COULD SEE A SOME MORE ORGANIZED AREAS BY LATER IN THE AFTERNOON...THUS LOWER POPS IN THE AFTN. NEXT UP IS THE WAVE FOR TONIGHT...MAINLY THIS EVENING. FORCING SIGNALS DRASTICALLY ON THE UPTICK IN THE LAST COUPLE OF RUNS OF DETERMINISTIC WRF AND GFS. THIS WAVE MOVING ACROSS ROCKIES AS WE SPEAK...AND HAS SOME DEEPER PACIFIC MOISTURE TO TAP...WITH AFOREMENTIONED SURGE OF LOW LEVEL MOISTURE AROUND BACKSIDE OF DEPARTING HIGH. WEAK/MOD BUT DEEP Q/G SIGNAL CROSSES SRN 2/3RD OF ARX CWA THIS EVENING AMIDST DEEP SATURATION. ISENTROPIC WORK /280-290K/ VERY SUPPORTIVE OF STRONG LIFT OVER THE SRN CWA. LATEST 11.06Z NAM-WRF NOW PUMPING OUT 0.30 INCHES OF LIQUID ACROSS SRN 2 TIERS OF COUNTIES...AND 11.00Z GFS NOT FAR BEHIND. BOTH 21Z AND 03Z SREF SHOW INCREASING PROBABILITIES...WITH 03Z SREF MEAN INDICATING 2 INCH PLUS OF SNOW IN GRANT COUNTY ALONG IL/WISC BORDER. THINK THIS SUPPORTS AT LEAST HIGH END LIKELY POPS RIGHT NOW AND SHOULD BE MOVED CATEGORICAL OVER SRN 1/2 OF CWA WITH NEXT ISSUANCE. FRONTOGENESIS IS STRONG ACROSS SRN 2 TIERS OF ARX CWA...AND EVEN CONCERNED ABOUT ANOTHER FRONTOGENETICAL BAND /800MB/ FURTHER NORTH OVER RST TO LSE LINE WHICH MAY BRING ACCUMS FURTHER NORTH FOR A TIME. STILL...ANTICIPATE THE LONGEST DURATION/STRONG FORCING ACROSS ALL OF NERN IA INTO SWRN WI...WHERE I AM RUNNING 2.0-3.5 INCHES OF ACCUMULATION. GIVEN STRONG CONSISTENT SIGNALS IN SREF/GFS/NAM WRF...AND ADDITIONAL SUPPORT IN SPC 5KM WRF AND HI RES CANADIAN...WOULD NOT BE AT ALL SURPRISED IF WE NEED TO MOVE TO AN ADVISORY FOR THE SRN 2 TIERS OF COUNTIES FOR 3-4 OR 3-5 INCHES OF SNOW. COBB DATA INDICATING SNOW-WATER RATIOS A LITTLE LESS THAN RECENTLY SEEN...DUE TO INFLUX OF WARMER AIR...MAINLY 11-13:1. NRN FRINGE OF SNOW WILL BE TOUGH /I-90 CORRIDOR/...AND THIS AREA COULD SEE ANYWHERE FROM A DUSTING TO 2 INCHES GIVEN WHAT SHOULD BE A TIGHT NRN FRINGE TO THE SNOW. FINALLY...LARGE WRN TROUGH MOVES INTO THE CNTL CONUS MONDAY AND GENS UP SIGNIFICANT/DEEPENING LOW PRESSURE OFF TO OUR SOUTH. NAM IS MUCH MORE NLY THAN ANY OTHER DETERMINISTIC RUN...THUS I AM IGNORING THE DECENT ACCUMULATIONS IT SENDS OUR WAY MONDAY NIGHT/TUES. THE SREF MEANS/PROBABILITIES AND GEFS PROBABILITIES DO NOT SUPPORT THIS PCPN THIS FAR NORTH INTO THE DRY NELY FLOW INTO THE SRN PLAINS LOW. I DID KEEP THE POPS IN THE FAR SOUTH FOR WHAT WILL BE A CLOSE CALL AS THE NRN FRINGE OF THE DEFORMATION/ISENTROPIC LIFT BRUSHES BY IN THE I-80/HWY 30 CORRIDORS. THIS WILL NEED TO BE WATCHED OVER THE NEXT 24 HOURS...BUT AS OF NOW...AGREEMENT IN ECMWF/GEFS/GFS SEEMS RATHER STRONG THAT THIS SYSTEM WILL PASS TO OUR SOUTH. WILL NEED TO WATCH WINDS ON MONDAY NIGHT/TUES FOR BLOWING SNOW OVER OPEN AREAS OF NERN IA WITH WHAT FALLS THIS EVENING. .LONG TERM...WEDNESDAY THROUGH SATURDAY PATTERN RE-AMPLIFICATION SEEMS IN THE CARDS IN THE WAKE OF THE STRONG SYSTEM TRAVERSING THE CNTL-ERN CONUS MON-WED. NEW 11.00Z GEFS MEAN AND ECMWF OPERATIONAL RUNS SHOWING HIGH AMPLITUDE WRN RIDGE/ERN TROUGH WITH ARX CWA IN STRONG NWLY FLOW. ECMWF SHOWS RATHER STRONG SHORTWAVE DIVING THROUGH THIS FLOW FRI/SAT SO THIS WILL HAVE TO BE WATCHED FOR SNOW CHANCES. OTHERWISE...TEMPERATURES STARTING OUT VERY COOL ON WEDNESDAY AS LOBE OF ARCTIC AIR MOVES THROUGH...THEN MODERATION AS PROXIMITY OF PACIFIC AIRMASS ALLOWS SOME WARM ADVECTION AHEAD OF THAT FRI/SAT WAVE. SHOULD SEE TEMPERATURES MODERATE BACK CLOSER TO NORMAL FOR THE FIRST TIME IN WEEKS...THOUGH LIKELY TO STAY JUST BELOW NORMAL GIVEN LOCATION OF RIDGE AXIS AND NWLY FLOW. MAY BE ANOTHER BRIEF DUMP OF ARCTIC AIR BEHIND THE WEEKEND SHORTWAVE TOO. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ BINAU wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 1039 AM CST SAT FEB 10 2007 .UPDATE... LATEST 16Z SURFACE ANALYSIS INDICATES ARCTIC HIGH OVER WESTERN IOWA AND EASTERN NEBRASKA. 12Z 850MB UPPER AIR PLOT INDICATES COLD POOL OF -17 AT MPX...GRB AND -12 DEGREES CELSIUS AT DVN THIS MORNING. CURRENT TEMPERATURES ARE RUNNING AROUND 5 DEGREES COOLER THAN YESTERDAY AT THIS TIME. LATEST RUC INDICATES ARCTIC COLD POOL OVER FORECAST AREA...COMBINED WITH ARCTIC HIGH BUILDING INTO EASTERN IOWA AND CENTRAL ILLINOIS THIS AFTERNOON. WILL UPDATE TO LOWER MAX TEMPERATURES ACROSS FORECAST AREA TODAY. && DTJ .PREV DISCUSSION... /ISSUED 352 AM CST SAT FEB 10 2007/ .SHORT TERM...THROUGH MONDAY SHORT TERM FOCUS WILL BE ON LIGHT SNOW CHANCES LATE TONIGHT AND SUNDAY...AND SYSTEM SKIRTING BY TO OUR SOUTH MON...WITH CONTINUED BELOW NORMAL TEMPERATURES. CURRENTLY...STRONG HIGH PRESSURE STILL RUNNING FROM SASKATCHEWAN SOUTHEAST TOWARDS SIOUX FALLS AND OMAHA. LIGHT NORTHWEST WINDS COMBINING WITH THE SUBZERO TEMPS TO CREATE LOCAL WIND CHILLS OF 15 TO 30 BELOW ZERO. WITH VERY FEW SITES MEETING CRITERIA-MANDATED 10 MPH...WILL HOLD OFF ON ADVISORY. SOME SUBTLE DIFFERENCES IN NWP MODEL SUITE THIS MORNING...BUT EFFECTS ARE PRETTY MARGINAL IN ARX CWA IN TERMS OF SENSIBLE WEATHER. TODAY...SURFACE HIGH TO QUICKLY SINK SOUTH INTO SRN IA BY THIS EVENING. CLEAR SKIES THIS MORNING WILL GIVE WAY TO INCREASING MID/HIGH CLOUDS THIS AFTERNOON AS NEXT WEAK PERTURBATIONS ZIP DOWN THE NWLY FLOW INTO THE REGION BY TONIGHT. PLENTY OF SUNSHINE THIS MORNING. AS PER LAST WEEK OR SO...UNDERCUT MOS TEMPS MOST AREAS...ESPECIALLY IN SERN MN/NERN IA PER PVS FORECAST. ANOTHER DAY WITH HIGH TEMPERATURES 15 TO 20 DEGREES BELOW NORMAL. SOME COLD WIND CHILLS THIS MORNING WILL QUICKLY MODERATE AS WINDS DECREASE AND BACK TO THE SOUTHWEST AS HIGH PRESSURE MOVES INTO IOWA. TONIGHT...STARTING TO SEE INCREASING SIGNAL IN OPERATIONAL RUNS OF 10.00Z GFS/WRF AND 21Z/03Z SREF OF A COUPLE WEAK WAVES TONIGHT/SUNDAY MORNING INCREASING THERMODYNAMIC LIFT OVER AREA. VERY LITTLE SIGNAL OF THESE SYSTEMS ALOFT...BUT MARKED WARM ADVECTION/ISENTROPIC SIGNALS. 275-285K LAYER DEPICTS INCREASING ASCENT AS LOWER LEVEL MOISTURE SURGES IN ON SWLY LOW LEVEL FLOW. BUFR SOUNDINGS /WRF AND GFS/ SHOWING MUCH OF THE OMEGA CENTERED VERY LOW ON THE SOUNDINGS...TIED DIRECTLY TO THIS ISENTROPIC LIFT/WARM ADVECTION. SREF NOW DEPICTS A RATHER DECENT SIGNAL FOR MEASURABLE SNOW...CENTERED SQUARELY ON ARX CWA FROM 09Z THROUGH 18Z AS ISENTROPIC OMEGA MAX CROSSES CWA. ALSO A WEAK 850-700MB Q/G SIGNAL WITH THE VERY WEAK MID LEVEL WAVE. WITH SATURATED PORTIONS OF SOUNDINGS AGAIN RESIDING IN OR VERY NEAR DENDRITIC ZONE /-12C TO -18C/...WON/T BE HARD TO BRING AN HOUR OR TWO OF DECENT SNOW TO THE AREA AS THIS BAND OF FORCING MOVES THROUGH. MOVED POPS INTO CHANCE RANGE FOR LATER TONIGHT AND SUNDAY MORNING ACROSS CWA...AND THIS WILL NEED TO BE MOVED FURTHER TOWARD LIKELY IF CURRENT SIGNALS PERSIST. ACCUMS WON/T BE MORE THAN AN INCH...AND MAY NOT BE MORE THAN A DUSTING TO A COUPLE TENTHS GIVEN WEAK FORCING. FOCUS SUNDAY NIGHT/MONDAY TURNS TO WRN ENERGY AND SFC LOW TO ORGANIZE OVER THE SRN PLAINS. COLD FRONT TIED TO AFOREMENTIONED WAVES SLIDES THROUGH SUNDAY EVENING AND SETS UP DRY NELY FLOW IN LOW LEVELS OVER MUCH OF CWA. HOWEVER...THIS BOUNDARY HANGS UP OVER CNTL PLAINS AS HEIGHT FALLS MOVE OUT INTO THE AREA SUNDAY NIGHT. INCREASING MIDLEVEL FORCING /FRONTOGENESIS/ TO OUR SOUTH WILL ORGANIZE BAND OF LIGHT SNOW TO OUR SOUTH SUNDAY NIGHT OVER IOWA...AND STILL NOT ENOUGH CONFIDENCE TO LOWER POPS FURTHER...AS SREF POINTS TO A FEW MEMBERS DRAGGING NRN FRINGE OF THIS FRONTOGENETICAL BAND ACROSS FAR SRN TIER OF CWA SUN NIGHT/MONDAY WITH LIGHT ACCUM POTENTIAL. DON/T WANT TO GIVE UP ON THIS TOO SOON DESPITE THE BETTER CHANCES OF DRIER LOW LEVEL AIR WINNING OUT. WILL MAINTAIN CHANCES FOR SNOW IN SRN CWA SUN NIGHT/MONDAY UNTIL SREF POPS DROP OUT OF CWA...WHICH THEY ARE NOT FOR NOW. BEST CHANCES WILL COME SUNDAY NIGHT AS FRONTOGENETICAL FORCING CLOSEST BY...BEFORE SLOWLY SAGGING SOUTHEAST WITH TIME. .LONG TERM...TUESDAY THROUGH FRIDAY EXTENDED FORECAST STILL CHARACTERIZED BY BELOW NORMAL TEMPERATURES...ESPECIALLY EARLY ON...BEFORE SLOW MODERATION IS SEEN. NEW 10.00Z ECMWF AND 10.00Z CANADIAN GLOBAL MODEL IN STRONG AGREEMENT IN AN OTHERWISE PERIOD OF INCREASING UNCERTAINTY ON HOW THE LARGE SCALE PATTERN WILL EVOLVE INTO THE SECOND HALF OF FEBRUARY. ON TUESDAY...HUGE 1045MB HIGH OVER THE DAKOTAS WILL DROP SOUTH AS LOW PRESSURE RIDES UP THE ERN SEABOARD. ONE MORE ARCTIC PUSH WITH THIS HIGH...AND LIKELY ANOTHER ROUND OF SUBZERO NIGHTS AS THE DRY/COLD AIRMASS FILTERS IN. TEMPERATURES TUES/WED MAY NEED TO BE MOVED DOWNWARD IN COMING FORECASTS. THIS HIGH SINKS SOUTH OFF THE GULF COAST BY FRIDAY WITH RAPID WARM ADVECTION BY NEXT WEEKEND...WITH TEMPERATURES PERHAPS RETURNING TO SOME SEMBLANCE OF NORMALCY...THOUGH LIKELY STILL BELOW CLIMO. SEEMS INCREASING SIGNALS THOUGH THAT PACIFIC AIRMASS /OR A DESCENDANT THEREOF/ WILL ACCOMPANY RIDGING INTO THE WRN CONUS NEXT WEEKEND...WITH ARCTIC AIR DEPARTING. MAY BE A SHORTWAVE OR TWO WITH WARM ADVECTION SNOW CHANCES AT SOME POINT THURS/FRI...BUT NOT ENOUGH OF A SIGNAL YET. BETTER CHANCES RIGHT NOW SEEM TO BE ON FRIDAY. WILL LET DAY CREW ASSESS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ BINAU wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 303 AM EST MON FEB 12 2007 ...INCREASED RAIN CHANCES THRU TUE NIGHT... .SYNOPSIS...WELL DEFINED SHORTWAVE INDICATED OVER THE CENTRAL GOMEX BY BOTH H2O VAPOR SAT PIX AND RUC ANALYSIS WITH LARGE SHIELD OF MID AND HIGH CLOUDINESS SPREADING ACROSS THE SE US. LIGHT TO MODERATE RAIN OCCURRING ACROSS THE S FL PENINSULA WHERE THE SHORT WAVE IS INTERACTING WITH AN OLD FRONTAL BOUNDARY. RADAR MOSAIC ALSO INDICATING VERY LIGHT RETURNS ACROSS CENTRAL FL...BUT AS YET THIS APPEARS TO BE VIRGA. ANOTHER ELONGATED SHORTWAVE EXTENDS FROM THE PAC NW TO EXTREME N MEXICO. CLOUDINESS HAS SLOWED TEMP DROP OVER MOST OF THE COUNTY WARNING AREA (CWA) WITH TEMPS RANGING FROM THE LOWER 40S OVER N ZONES TO THE LOWER 50S IN THE S. INVERTED TROF IS LOCATED OVER OUR ATLC WATERS. .SHORT TERM...MODELS SHIFT S SHORTWAVE E ACROSS THE REMAINDER OF THE GOMEX AND THE FL PENINSULA TODAY. MEANWHILE...N SYSTEM AMPLIFIES AND MOVES ACROSS THE PLAINS. MODELS AGREE THAT THESE SYSTEMS DON`T PHASE UNTIL BOTH ARE NE OF OUR AREA. AT THE SFC...LOW PRESSURE SYSTEM WILL MOVE E INTO THE SE US...THEN SHIFT NE AS ANOTHER LOW DEVELOPS OFF THE SE COAST AND MERGES WITH THE AFOREMENTIONED LOW OFF THE NEW ENGLAND COAST. GFS...AND TO SOME EXTENT THE NGM....DEVELOP A WEAK SFC LOW OVER THE E GOMEX LATE TODAY AND MOVE IT ACROSS S CENTRAL FL. REGARDLESS OF THE STRENGTH OF THE LOW...POSITION OF DEVELOPING WARM FRONT WILL LIKELY STAY S OF OUR CWA UNTIL THIS WEAKNESS MOVES AWAY AND SE FLOW CAN BECOME BETTER ESTABLISHED AHEAD OF STRONGER LOW. HOWEVER...INCREASING THICKNESSES AND GENERAL VEERING LOW LEVEL FLOW WILL BRING WARMER TEMPS ACROSS THE AREA. HAVE BUMPED UP POPS FOR TODAY ACROSS MAINLY THE S 1/3 OF THE AREA DUE TO MODEST ISENTROPIC LIFT AND GRADUALLY INCREASING MOISTURE. EXPECT MOST OF THIS PRECIP TO BE LIGHT AND STRATIFORM IN NATURE. PRECIP INCREASES TONIGHT ACROSS MAINLY E AREAS AS WARM FRONT BEGINS TO LIFT N. PRECIP FIELDS BECOME INCREASINGLY CONFUSED TUE AFTN AND EVENING AS LOWS CONSOLIDATE N OF THE AREA. NONE OF THE MODELS INDICATE MUCH OF AN ORGANIZED SQUALL LINE WITH THIS SYSTEM...EITHER ALONG THE PRE-FRONTAL TROF OF THE FRONT ITSELF... PROBABLY DUE TO COMPETING FLOW FROM SFC FEATURES PROVIDING LIMITED LOW-LEVEL CONVERGENCE. NAM DOES HINT AT ORGANIZED CONVECTION W OF THE AREA TUE AFTN...BUT IT MOSTLY FALLS APART BEFORE REACHING OUR W ZONES. STILL EXPECT ISOLD STRONG TO SVR STORMS...ESPECIALLY IF ANY BREAKS IN CLOUD COVER PROVIDE AN INCREASE IN INSTABILITY. GREATEST THREAT FROM ANY STORMS APPEARS TO BE HAIL ATTM WITH 500 MB TEMPS AROUND -15 C AND ENUF SHEAR TO TILT STORMS TUE AFTN AND EVENING. CLOUDS AND PRECIP SHOULD BEGIN TO EXIT AFTER MIDNIGHT TUE NIGHT...BUT 850 MB PROGS INDICATE POSSIBILITY OF WRAP-AROUND LOW CLOUDS THRU WED OVER N ZONES. MAV AND NAM MOS TEMPS ARE IN GOOD AGREEMENT AND A BLEND WAS USED WITH SLIGHT ADJUSTMENTS BASED ON CLOUD COVER. FOG THREAT WILL BE LIMITED BY CLOUDS THIS MORNING AND BY CLOUDS AND INCREASING LOW LEVEL WINDS TUE MORNING. WILL MENTION PATCHY FOG AT BEST. .LONG TERM...COLD STRETCH STILL LOOKS LIKELY LATE THIS WEEK... SEVERAL DAYS OF SUB-FREEZING LOWS OVER INLAND SECTIONS. TEMPS EXPECTED TO REBOUND SLIGHTLY SAT BEFORE ANOTHER FRONT SWEEPS ACROSS THE AREA. ONLY MINOR CHANGES HAVE BEEN MADE TO TEMPS THIS PACKAGE. && .AVIATION...THE HIGH CLOUDS HAVE HELPED DELAY THE ONSET OF FOG BUT THIN SPOTS COMING IN LATER TONIGHT/EARLY TUES AM WILL HELP PROMOTE THE FORMATION OF FOG. HAVE GONE WITH MVFR AFTER 09Z AT JAX...CRG...SSI AND PUT IN A TEMPO AT GNV FOR IFR BETWEEN 09Z AND 13Z. SE WINDS BRING IN INCREASED MOISTURE TO THE AREA AND HAVE GONE WITH CIGS AROUND 3000 FT THROUGH THE MORNING...INCREASING TO VFR DURING THE AFTERNOON. AS LOW PRESSURE BEGINS TO DEVELOP AND MOVE TOWARDS THE SOUTHERN FL PEN...SCATTERED SHOWERS WILL FORM IN THE AFTERNOON...SOME OF WHICH MAY MOVE THROUGH THE SOUTHERN AREAS. HAVE GONE WITH SHOWERS IN THE VICINITY AT GNV AFTER 19Z. && .MARINE...PRESSURE GRADIENT BEGINS TO TIGHTEN TODAY AS HIGH PRESSURE MOVES OFFSHORE AND LOW PRESSURE TRACKS TOWARD THE SOUTHERN FL PEN. WINDS/SEAS INCREASE TO SCEC LEVELS OFFSHORE TODAY. INCREASING SE FETCH BUILDS SEAS TO THE 5 TO 7 FOOT RANGE OFFSHORE TONIGHT AND TUESDAY AM FOR THE FL OFFSHORE AND HAVE GONE WITH SCA THERE FOR TONIGHT INTO TUES AM. SCA CONDITIONS EXPECTED TUES NIGHT/WED AS COLD FRONT PUSHES THROUGH THE WATERS. && .PRELIMINARY POINT TEMPS/POPS... AMG 70 52 71 48 / 0 10 60 50 SSI 67 55 69 52 / 10 30 50 50 JAX 71 55 73 52 / 20 30 40 40 SGJ 69 59 72 54 / 20 40 40 40 GNV 72 53 75 51 / 30 30 50 40 OCF 71 55 75 52 / 40 30 50 40 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...SMALL CRAFT ADVISORY FROM 1 AM TO 12 PM EST TUESDAY FOR FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE- ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE. && $$ CARROLL/PETERSON fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 520 AM EST MON FEB 12 2007 .SHORT TERM... FLOW ALOFT BECOMING SOUTHWESTERLY AHEAD OF AN APPROACHING TROUGH. COMBINED WITH INCREASING LOW LEVEL FLOW AS THE PERSISTENT SURFACE RIDGE THAT HAS DOMINATED THE REGION SLIPS OFF THE EAST COAST THIS ALLOWS TEMPERATURES TO WARM NICELY TODAY. MODELS IN FAIRLY GOOD AGREEMENT WITH THE MOVEMENT OF THE UPPER TROUGH AND THE ASSOCIATED SURFACE LOW. GFS IS STILL A LITTLE MORE EAGER TO SHIFT THE SURFACE LOW FURTHER EAST FASTER TUESDAY AS THE COASTAL LOW DEEPENS OFF THE CAROLINA COAST. ALL IN ALL THE EFFECT IS THE SAME FOR GEORGIA AS A SIGNIFICANT RETURN OF MOISTURE SURGES NORTHWARD AHEAD OF THE LOW. MODELS DO NOT DEVELOP A SUPER LOW LEVEL JET ACROSS THE REGION...BUT THERE SHOULD BE ENOUGH LOW LEVEL SHEAR FOR THE THREAT OF SOME SEVERE STORMS AS WE MOVE INTO TUESDAY AFTERNOON. THERE WILL BE SOME WRAP AROUND MOISTURE AS THE SYSTEM EXITS TUESDAY EVENING...BUT I THINK THE PRECIPITATION WILL BE ENDING BEFORE THE SIGNIFICANT COLD AIR MOVES IN LIMITING THE CHANCES FOR ANY WINTRY CHANGEOVER. .LONG TERM... THE UPPER LEVEL PATTERN GOES THROUGH A REAMPLIFICATION DURING THE EXTENDED FORECAST PERIOD WITH A LARGE RIDGE BUILDING OUT WEST AND THE EASTERN TROUGH DIGGING DOWN THE EAST COAST. THIS PUTS THE FORECAST AREA BACK INTO A COOL AND DRY NORTHWEST FLOW PATTERN. THE UPPER PATTERN IS A BIT MORE PROGRESSIVE THAN THIS SET UP WAS THE PAST COUPLE OF WEEKS WITH THE WESTERN RIDGE FORECAST TO SHIFT EAST SLOWLY OVER TIME. IN THE MEANTIME A RATHER STRONG SHORTWAVE DIGS DOWN THE BACKSIDE OF THE EASTERN TROUGH BRINGING US A CHANCE FOR SOME PRECIPITATION NEXT WEEKEND. AT THIS TIME THE GFS IS KEEPING THE REGION COOL ENOUGH FOR A POSSIBILITY THIS COULD END UP BEING AT LEAST A RAIN SNOW MIX. THIS IS AT THE END OF THIS FORECAST AND A LOT CAN CHANGE IN 6 DAYS SO CONFIDENCE IS STILL VERY LOW. && .AVIATION... LATEST 06Z RUN OF NAM AND GFS INDICATE LOW LEVEL MOISTURE WILL BE MOVING INTO THE SOUTHERN AND EASTERN PART OF THE CWA EARLIER THAN PREVIOUS RUN. NAM AND GFS HAVE 925MB MOISTURE INCREASING OVER FLORIDA AND MOVING RAPIDLY INTO CENTRAL AND EARN GA BY 18Z. AM NOT READY TO BUY INTO THIS YET BUT WILL BEGIN TRENDING LOWER LEVEL CLOUDS THIS AFTERNOON IN MCN AND AHN. THIS MOISTURE WILL SPREAD WEST AND NORTH AFTER 00Z BRINGING CIGS DOWN TO 1500 TO 2500 FT BY 06Z TO 09Z ALL SITES. OTHER PROBLEM IS THE 5K FT CLOUDS OVER AL. MODELS APPEAR TO BE A BIT SLOW IN SPREADING THIS EASTWARD BUT ALSO ADVECT THE MOISTURE NORTHEAST KEEPING IT OUT OF ATL. THE RUC CONTINUES TO SHOW THIS TREND AS WELL. HOWEVER SEEING THAT THE CLOUDS ARE FURTHER EAST THAN WHAT THE MODELS SHOW FOR THIS TIME WILL ADD SCT050 IN ATL AREA AROUND 15Z. WINDS WILL BE SOUTHEAST BUT LESS THAN 10 KTS. && .PRELIMINARY POINT TEMPS/POPS... ATHENS 64 43 59 38 45 / 0 5 80 40 5 ATLANTA 64 48 61 37 43 / 0 5 80 40 5 BLAIRSVILLE 59 40 57 33 41 / 5 10 80 50 5 CARTERSVILLE 62 44 58 35 40 / 5 10 80 50 5 COLUMBUS 67 48 65 41 50 / 0 5 60 30 5 GAINESVILLE 62 46 58 37 44 / 5 5 80 50 5 MACON 68 48 66 43 53 / 0 5 60 30 5 ROME 61 43 63 32 43 / 5 20 90 50 5 PEACHTREE CITY 63 44 63 35 44 / 0 5 80 40 5 VIDALIA 69 52 68 48 56 / 0 10 60 30 5 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 20/20 ga AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 645 PM CST SAT FEB 10 2007 .DISCUSSION... S/W APPEARS AHEAD OF SCHEDULE AS VISIBILITIES DROP TO 2 MILES IN THE NORTH AND 5-7 WEST CENTRAL. WILL ALSO ADJUST TEMPS AS FALL HAS PRETTY MUCH ENDED AND STEADY TO SLOWLY RISING. RUC HANDLING THIS SITUATION WELL. .PREVIOUS DISCUSSION... PLENTY OF ISSUES IN THIS FORECAST AS SIGNIFICANT SYSTEM PASSES THROUGH THE REGION EARLY NEXT WEEK. CURRENTLY...SFC RIDGE PASSING ACRS THE STATE WITH LIGHT WINDS AND UNSEASONABLY COOL TEMPS. THE RIDGE WL CONTINUE ITS EASTWARD PROGRESS OVERNIGHT AS WAA INTENSIFIES. CLDS ALREADY SPREADING INTO WESTERN IA IN ASSOCIATION WITH THE WAA AND EXPECT THEM TO MOVE ACRS ENTIRE CWA OVERNIGHT. SCATTERED FLURRIES ALSO REMAIN PSBL WITH THE SURGE OF WARMER AIR. TEMPS WL BOTTOM THIS EVENING WITH SLOWLY RISING READINGS DURING THE NIGHT WITH INCREASING GRADIENT AND CLDS. IA WL BE IN THE "WARM SECTOR" ON SUNDAY WITH READINGS CLIMBING TO THEIR WARMEST LEVELS SINCE JANUARY 26TH. HAVE MODERATED THE GUIDANCE SOMEWHAT WITH SNOW COVER AND WINDS NOT OVERLY CONDUCIVE TO LARGE WARMUP...BUT THIS WL HAVE TO BE WATCHED. OTHERWISE...COLD FRONT WILL PUSH INTO NORTHERN IOWA BY AFTERNOON ASSOCIATED WITH A SHORTWAVE ACROSS SOUTHERN CANADA. SOME FLURRIES OR LGT SNOW MAY BE ASSOCIATED WITH THIS BOUNDARY BUT THE LARGE INCREASE IN PCPN PREVIOUSLY THOUGHT DOES NOT LOOK AS LIKELY NOW AND HAVE CUT BACK POPS SIGNIFICANTLY DURING THE AFTERNOON. SUNDAY NIGHT INTO MONDAY WL SEE CYCLOGENESIS OCCUR IN SE COLORADO AS SHORTWAVE MOVES THROUGH THE WESTERN U.S. BOUNDARY IN IA WL EASE SLOWLY SOUTH OVERNIGHT WITH MOISTURE TRANSPORT INCREASING ACRS THE PLAINS AHEAD OF THE DEVELOPING LOW. IT NOW APPEARS PCPN SHOULD BEGIN BREAKING OUT AFTER MIDNIGHT ACRS THE SOUTH IN INCREASING WAA WITH A BAND FARTHER NORTH ASSOCIATED WITH SOME MIDLEVEL FRONTOGENETICAL FORCING. HAVE TRENDED POPS HIGHER AS THE NIGHT PROGRESSES. SOUNDINGS DO INDICATE SOME WARM AIR ALOFT AND SOME MIXTURE REMAINS PSBL IN THE FAR SOUTH PRIOR TO TRANSITION TO ALL SNOW BY MONDAY AS PCPN INTENSITY INCREASES. MONDAY THROUGH MONDAY NIGHT WL SEE STRONG ISENTROPIC LIFT ACRS THE STATE WITH BEST UVV ACRS THE SOUTH. PCPN RATES EXPECTED TO INCREASE DURING THE DAY WITH HIGHEST QPF IN THE SOUTH. QPF AND HPC GUIDANCE WOULD CERTAINLY SUGGEST AMOUNTS APPROACHING OR EXCEEDING WARNING CRITERIA BY TUESDAY MORNING. BUFKIT PCPN OVERVIEW AND COBB PCPN ALSO GIVE SIGNIFICANT AMOUNTS ACRS SOUTHERN THIRD OF CWA. GIVEN RECENT MODEL UNCERTAINTY AND COLLABORATION WITH SURROUNDING OFFICES...WL ISSUE STRONGLY WORDED HWO BUT WOULD NOT BE SURPRISED TO SEE SOME HEADLINES ISSUED TONIGHT. WINDS ALSO APPEAR TO CRANK UP BY MONDAY NIGHT AS GRADIENT TIGHTENS AROUND DEEPENING LOW SO BLOWING SNOW MAY BECOME A PROBLEM AS WELL. SYSTEM TO DEPART ON TUESDAY WITH SOME LINGERING LGT SNOW ACRS THE SE IN THE MORNING. THEN LARGE CANADIAN HIGH WL SETTLE ACRS THE STATE WITH COLD TEMPS ONCE AGAIN ALONG WITH CLEARING SKIES. REMAINDER OF EXTENDED IS DRY WITH TEMPS REMAINING BELOW NORMAL ALTHOUGH SOME MODERATION IS EXPECTED BY LATE NEXT WEEK. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ COGIL/FORSTER 203/39 ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 235 AM CST MON FEB 12 2007 .DISCUSSION... THE UPPER LEVEL WAVE THAT WILL BE RESPONSIBLE FOR STRENGTHENING AND SHIFTING OUR NEXT SURFACE CYCLONE EAST...IS PROGRESSING AS SCHEDULED OVER THE INTERMOUNTAIN WEST. WATER VAPOR IS SHOWING SOME INTERESTING SIGNATURES OVER CENTRAL ARIZONA THIS MORNING...SOME EVIDENCE THAT A CLOSED CIRCULATION EXISTS AND THAT THE STRENGTH AND STRUCTURE OF THE UPPER TROUGH MAY BE DIFFERENT THAN WHAT MODELS HAVE SUGGESTED THUS FAR. THIS SYSTEM WILL BEGIN TO IMPACT THE REGION TODAY IN THE FORM OF RAIN AND POTENTIALLY A FEW THUNDERSTORMS. PRECIPITATION TYPE AND CHANCES CONTINUE TO BE THE PRIMARY FORECAST CHALLENGES. HEAVY RAIN LEADING TO POSSIBLE FLOODING OVER SOUTH CENTRAL/CENTRAL MISSOURI WAS ALSO CLOSELY ANALYZED. SHORT TERM (TODAY - TUESDAY)... CONCERNS ARE INCREASING REGARDING THE POSSIBILITY OF A CLOSED OFF CIRCULATION DEVELOPING OVER ARIZONA. NONE OF THE MODELS HAD SUGGESTED THIS TO HAPPEN. IF STRENGTHENING OCCURS AS THE CIRCULATION SHIFTS OFF THE HIGHER TERRAIN OF NEW MEXICO...THEN ENHANCED LIFT ON IT`S NORTHERN FLANK WOULD FAVOR A TRACK DIRECTLY OVER THE CWA. MEANWHILE TIMING WOULD FAVOR RAIN CHANGING OVER TO SNOW AT ABOUT THIS TIME. THE LATEST RUC80 MAY BE CATCHING ON WITH THE SYSTEM`S STRUCTURE. 500 MB THETA E FIELDS ARE SHOWING A HIGH LEVEL TROWAL DEVELOPING BY 18Z THAT EXTENDS FROM NEAR WICHITA BACK INTO THE PANHANDLES. I`M NOT GOING TO MAKE ANY DRASTIC CHANGES TO THE SNOWFALL ACCUMULATION FORECAST AT THIS TIME...BUT WE`LL BE KEEPING A CLOSE EYE ON THIS OVER THE NEXT FEW HOURS. LARGE SCALE ASCENT HAS COMMENCED OVER WEST TEXAS AND OKLAHOMA EARLY THIS MORNING. RAIN IS INCREASING IN AREAL COVERAGE...WHICH WILL EVENTUALLY SPREAD OVER SE KANSAS AND THE MISSOURI OZARKS LATER TODAY. AREAL COVERAGE OF MEASURABLE RAIN SHOULD BE 100%...AND THATS WHAT WE`LL BE GOING WITH IN THE OFFICIAL FORECAST. HEAVY RAIN IS LIKELY AS MODELS SUGGEST PWATS APPROACHING 1.00...WHICH IS HIGH FOR THE TIME OF YEAR. DUE TO THE LACK OF FEBRUARY VEGETATION...RAINFALL SURPLUS OVER SOUTH CENTRAL MISSOURI...AND A FROZEN GROUND...WE`LL BE ISSUING A FLOOD WATCH FOR AREAS ALONG AND SOUTH OF I-44...FROM SPRINGFIELD TO ROLLA. MODELS CONTINUE TO SHOW MUCH COLDER AIR SPREADING IN BEHIND THE LOW CENTER LATE TONIGHT INTO EARLY TUESDAY MORNING. RAIN WILL CHANGE OVER TO SNOW FROM NORTHWEST TO SOUTHEAST...SOMETIME AFTER MIDNIGHT TONIGHT. RESIDUAL FLURRIES OR LIGHT SNOW SHOWERS WILL BE POSSIBLE THROUGH TUESDAY AFTERNOON...WITH THE SYSTEM SHIFTING EAST OF THE REGION BY TUESDAY NIGHT. LONG TERM (WEDNESDAY - SUNDAY)... COLD TEMPERATURES WILL FOLLOW OUR PREVIOUSLY MENTIONED ACTIVE WEATHER. LOWERED TEMPERATURES FROM WEDNESDAY THROUGH FRIDAY IN JUST ABOUT EVERY PERIOD. THE ARCTIC HIGH IS STILL PROGGED TO SLIDE DOWN THE PLAINS AND TRACK ALMOST DIRECTLY OVER THE REGION BY THURSDAY AFTERNOON. TEMPERATURES UNDERNEATH THE HIGH...OR OVER WESTERN CANADA...ARE CURRENTLY APPROACHING -25 TO -30 DEGS. A WARM UP MAY BE IN SIGHT ACCORDING TO THE LATEST GFS LONG RANGE PROGS. BY NEXT WEEKEND OR EARLY NEXT WORK WEEK...THE MODELS SUGGESTS THAT A LONG WAVE RIDGE WILL BUILD OVER MIDDLE AMERICA. THIS SUGGESTED PATTERN HAS NOT BEEN OBSERVED FOR TWO OR THREE MONTHS. ONGOING PRECIPITATION FORECASTS IN THE EXTENDED LOOKED GOOD...AND MADE NO CHANGES. CRAMER && .AVIATION... FOR THE 0600 UTC KSGF/KJLN TAFS... MVFR CEILINGS CONTINUED THIS EVENING WHILE GRADUALLY LOWERING. SOME VERY LIGHT DRIZZLE HAS DEVELOPED AT KSGF DURING THE PAST HOUR AND THE VISIBILITY...WHILE STILL VFR...HAS BEEN AFFECTED. WILL DROP THE VISIBILITY INTO THE MVFR CATEGORY LATER TONIGHT WHICH IS FAVORED BY CONDITIONAL CLIMO. RAIN SHOULD SPREAD INTO THE AREA NEAR SUNRISE...AND HAVE CONDITIONS LOWERING TO IFR DURING THE MORNING. PROGGED SOUNDINGS INDICATE LOW CEILINGS WILL CONTINUE INTO THE EVENING HOURS. DSA && .SGF WATCHES/WARNINGS/ADVISORIES... MO...FLOOD WATCH SOUTH OF I44 AND EAST OF US 65 THROUGH TUESDAY AFTERNOON. KS...NONE. $$ WFO SGF mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1138 PM CST SUN FEB 11 2007 .AVIATION... FOR THE 06Z TAFS... MAIN CONCERN THROUGH THE NEXT 24 HOURS REMAINS PRECIPITATION TYPE TOWARD THE END OF THE CYCLE. IN THE SHORT TERM...MVFR CEILINGS HAVE ENVELOPED THE AREA WITH A STEADY DROP WEST OF THE KS/MO BORDER DUE TO EASTERLY UPSLOPE. THESE SHOULD REMAIN FAIRLY STEADY AROUND 2KFT AGL OVERNIGHT...WITH VISIBILITIES GENERALLY IN THE 4-6SM RANGE AS SOME PATCHY LIGHT DRIZZLE ACCOMPANIES THE MODEST WARM AIR/MOISTURE ADVECTION. CURRENT FORECAST CALLS FOR THE WEAK WARM FRONT STRETCHING ACROSS NEBRASKA AND IOWA TO DISSOLVE TOWARD DAYBREAK AS A SECONDARY FRONT DEVELOPS FROM KTUL-KSGF-KSTL. THIS WILL ALLOW WINDS TO BACK INTO THE EAST AND EVENTUALLY NORTHEAST. HOWEVER...WITH THE AIRMASS ALREADY IN PLACE...THIS IS NOT A COLD ADVECTION DIRECTION AND AS PRECIPITATION BEGINS TO OVERSPREAD THE AREA TOWARD NOON...RAIN IS EXPECTED. GENERALLY SPEAKING... TEMPERATURES WILL DECREASE WITH HEIGHT SO PILOTS WILL LIKELY ENCOUNTER A FAIRLY PROGRESSIVE RAIN TO SNOW CHANGEOVER BETWEEN 5-7KFT AGL. AS SURFACE LOW PRESSURE TRACKS INTO ARKANSAS MONDAY EVENING...WINDS OVER NW MO WILL RAPIDLY INCREASE AND BEGIN TO SHIFT INTO THE NORTHEAST. GUSTS OF 25 TO 30KTS MAY BECOME FREQUENT TOWARD DAYBREAK TUESDAY. THE TIMING OF THE COLD AIR ASSOCIATED WITH THIS GRADUAL WIND SHIFT REMAINS QUESTIONABLE...AND MAY NOT OCCUR AT THE KANSAS CITY TERMINALS UNTIL MIDNIGHT TUESDAY. FOR THIS REASON HAVE DELAYED THE ONSET OF SNOWFALL AND REDUCED THE CHANCES FOR BOTH KMKC/KMCI. BOOKBINDER && .DISCUSSION... MONDAY THROUGH TUESDAY CONTINUES TO BE THE FOCUS AS A SIGNIFICANT WINTER STORM WILL AFFECT THE REGION. GFS/NAM/SREF ARE IN GOOD AGREEMENT WITH RESPECT TO THE TRACK OF THE SURFACE LOW. DID NOTICE THAT LAST COUPLE OF MODEL RUNS HAVE TAKEN THE SURFACE LOW A TAD FURTHER SOUTH. MODELS ALSO CLOSE ON TIMING/STRENGTH OF MID LEVEL SHORTWAVE THROUGH MONDAY NIGHT...WITH THE GFS A TAD FASTER THAN THE NAM. PRIMARY DIFFERENCES...ALTHOUGH MINOR...ARE WITH RESPECT TO THE MASS FIELDS...AND THEY COULD HAVE SIGNIFICANT EFFECTS ON THE SENSIBLE WEATHER. OVERALL FELT THE GFS/SREF OFFER THE BEST CONTINUITY WITH A DOWNWARD ADJUSTMENT TO THE GFS QPF...AT LEAST INITIALLY. SOUTHERLY BOUNDARY LAYER WINDS HAVE EFFECTIVELY DRAWN UP WARMER MORE MOIST AIR. NOW THAT THE LOW CLOUDS ARE ROLLING IN TEMPERATURES OVER THE WESTERN AND SOUTHERN CWA SHOULD ONLY DRIFT DOWNWARD WHILE AN EARLY EVENING LOW ANTICIPATED IN THE NORTHEASTERN COUNTIES BEFORE REBOUNDING ONCE THE CLOUDS AND MOISTURE MOVE IN THIS EVENING. HAVE ONLY MADE MINOR ADJUSTMENTS TO THE OVERALL GRIDS ON PLACEMENT AND TIMING OF THE DIFFERENT WEATHER TYPES. SLEET NOT AS MUCH OF AN ISSUE BUT FREEZING RAIN AND/OR FREEZING DRIZZLE COULD BECOME A MORE SIGNIFICANT ISSUE. STILL EXPECTING AN EAST-WEST FRONTAL BOUNDARY TO SET UP BY TOMORROW MORNING ACROSS NORTHERN MO. ONCE THE FRONT SETS UP IT SHOULD HOLD STEADY THROUGH THE DAYLIGHT HOURS AND WAIT TILL THE SURFACE LOW TRACKS SOUTH AND EAST OF THE CWA. ONCE THAT OCCURS THE COLDER AIR NECESSARY TO SUFFICIENTLY COOL THE COLUMN FOR A CHANGE OVER TO SNOW WILL SURGE SOUTHWARD. RIGHT NOW THAT LOOKS LIKE IT WILL BEGIN MID TO LATE AFTERNOON OVER THE FAR NORTHERN COUNTIES. UNTIL THEN INSPECTION OF THE MODEL SOUNDINGS INDICATE A LACK OF ICE CRYSTALS ACROSS NORTHERN MO SO FREEZING PRECIPITATION WILL BE THE PRIMARY WEATHER TYPE WHILE AREAS SOUTH OF A KANSAS CITY TO MOBERLY LINE SHOULD SEE ALL RAIN. THAT BEING SAID WILL NEED TO KEEP AN EYE ON MORNING TEMPERATURES AND ANY PRECIPITATION OVER THE EXTREME SOUTHEAST COUNTIES AS THEY WILL BE FURTHEST FROM THE MORE MOIST AIR AND MAY BE COOL ENOUGH AT THE START OF THE MORNING FOR SOME PATCHY LIGHT FREEZING RAIN. TEMPERATURES SHOULD MOVE LITTLE DURING THE DAY. PRIMARY LIFT WILL ARRIVE MONDAY NIGHT AS STRONG ISENTROPIC ASCENT CENTERED ON THE 300K SURFACE AND PRONOUNCED SLOPED FRONTOGENIC FORCING WILL LEAD TO HEAVIER SNOW RATES ACROSS NORTHERN MO. STILL CONCERNED ABOUT THE 3-4 G/KG OF MOISTURE AVAILABLE FOR SNOW PRODUCTION BUT TIME CROSS SECTIONS SHOW THE CENTER OF THE BEST UPWARD VERTICAL MOTION IS NOW CENTERED BELOW THE FAVORED DENDRITIC GROWTH ZONE. IF THIS REGION OF UVV SHIFTS UPWARDS THEN LATER FORECASTS WILL NEED TO CONSIDER INCREASING SNOW AMOUNTS. LATER SHIFTS WILL ALSO NEED TO KEEP AN EYE ON EVOLUTION OF CONVECTION. EXPECT ANY THUNDER ON MONDAY TO OCCUR JUST SOUTH OF THE CWA BUT IF THE MODELS SHIFT THE SYSTEM TO THE NORTH THEN THIS WILL NEED TO BE REVISITED. PVU PROGS ALSO INDICATE POTENTIAL FOR CONVECTIVE SNOWS WITHIN THE DEFORMATION ZONE WHICH FORMS LATE MONDAY NIGHT OVER EASTERN KS. THIS WAS PRIMARY REASON TO EXTEND THE WINTER STORM WATCH THROUGH TUESDAY MORNING AS ACCUMULATING SNOWS WILL LAST THROUGH TUESDAY MORNING. LATER SHIFTS WILL ALSO NEED TO CONSIDER WHETHER OR NOT ENOUGH SNOW WILL FALL UNDER THE DEFORMATION ZONE TO MEET WARNING CRITERIA. STILL A WAYS OUT BUT JUST ANOTHER ITEM TO CONSIDER. MJ WEDNESDAY-SUNDAY... FOR A COUPLE DAYS FOLLOWING THE EARLY WORK WEEK WINTER STORM TEMPERATURES ACROSS THE CENTRAL PLAINS WILL REMAIN WELL BELOW NORMAL. A COLD SURFACE HIGH WILL FLOW SOUTH AS THE WINTER STORM SHORTWAVE EXITS THE PLAINS. TRENDED WEDNESDAY AND THURSDAY TEMPERATURES DOWN AS A RESULT. THURSDAY SHOULD SEE A SLOW BEGINNING TO A WARMING TREND THAT WILL PERSIST INTO THE WEEKEND. BY LATE IN THE WORK WEEK A NORTHERN STREAM FLOW WILL ATTEMPT TO REESTABLISH ITSELF ACROSS THE WESTERN HALF OF THE CONUS AS THE FLOW ACROSS THE PACIFIC SPLITS. THIS MAKES FOR A MESSY PATTERN IN THE OFFING ACROSS THE PLAINS FOR NEXT WEEKEND...AND BY MESSY I MEAN HARD TO PIN DOWN WITH LOTS OF UNCERTAINTY. TEMPERATURES WILL MODERATE BACK TOWARDS SEASONALLY NORMAL VALUES AS THE PROGGED WEST COAST RIDGE MOVES SLOWLY EAST. HOWEVER...CONFIDENCE IN PLACEMENT OF ANY WAVES AND THEIR TIMING IS VERY POOR OWING TO THE SPLIT FLOW. THEREFORE...HAVE AVOIDED ATTACHING POPS TO ANY OF THE SHORTWAVES PROGGED TO COMING ZIPPING THROUGH PLAINS OVER THE LAST HALF OF THE FORECAST AT THIS TIME. CUTTER .PREV DISCUSSION... 505 AM... PRIMARY FORECAST CONCERN WILL BE THE POTENTIAL FOR A SIGNIFICANT WINTER STORM ACROSS THE AREA TO BEGIN THE WORK WEEK. CURRENT RUC ANALYSIS AND WV IMAGERY SHOWS NORTHWEST FLOW ALOFT OVER THE REGION WITH THE ANTICIPATED WINTER WEATHER PRODUCING UPPER WAVE FINALLY APPROACHING THE WEST COAST. SURFACE HIGH PRESSURE WAS GRADUALLY SHIFTING TO THE EAST THIS MORNING WHICH WILL ALLOW FOR SOUTHERLY WINDS AND INCREASING MOISTURE AHEAD OF THE APPROACHING UPPER SYSTEM. FORECAST GRIDS GENERALLY SIDED TOWARD THE GFS AND SREF GUIDANCE AS THEY HAVE BEEN THE MOST CONSISTENT WITH THERMAL FIELDS AND THE GFS HAS BEEN MORE CONSISTENT WITH ITS PLACEMENT WITH THE HEAVIER QPF. INITIAL CHANGE TO THE GRIDS WAS TO REDUCE POPS TONIGHT FROM LIKELY INTO THE CHANCE RANGE AS THE BETTER ISENTROPIC LIFT WON`T BE REACHING THE AREA UNTIL TOWARD DAWN. IN ADDITION...THE 21Z RUN OF THE SREF WAS POINTING MORE IN THE DIRECTION OF CHANCE POPS. STILL UNCERTAINTY REGARDING PRECIPITATION TYPES AND HOW FAST THE COLDER AIR WILL BE DRAWN SOUTHWARD AS SURFACE LOW TRACKS ACROSS THE RED RIVER VALLEY AND INTO LOWER MISSISSIPPI VALLEY BY TUESDAY. MEAN SREF DATA SHOWS BOTH THE SURFACE FREEZING LINE AND 0 DEG C LINE AT 850 MB ONLY MAKING VERY SLOW SOUTHWARD PROGRESS ACROSS THE AREA ON MONDAY...WITH THE PROGGED FREEZING LINE NOT MAKING IT TO THE METRO AREA UNTIL BETWEEN 21Z AND 00Z TUESDAY. HOWEVER...GFS POINT SOUNDINGS DO NOT SHOW A STRONG WARM LAYER ALOFT AND THERE IS CONCERN REGARDING HOW MUCH THE EXPECTED STRONG VERTICAL MOTION WILL COOL THE LOWER ATMOSPHERE. THE GFS HAS BEEN FAIRLY CONSISTENT IN BRINGING STRONG OMEGAS AND MID- LEVEL FRONTOGENESIS INTO THE NORTHERN HALF OF THE FORECAST AREA MONDAY INTO MONDAY EVENING. LOCATIONS NORTH OF THE INTERSTATE 70 CORRIDOR WILL LIKELY GET THE BEST FORCING AND HEAVIEST QPFS IS THIS FORCING PANS OUT. WILL START OUT THE SOUTHERN HALF OF THE FORECAST AREA AS ALL RAIN MONDAY MORNING...WITH A WINTERY MIX ACROSS OUR FAR NORTHERN 2 OR 3 TIERS OF COUNTIES. WILL ANTICIPATE THAT COLD AIR WILL MAKE PROGRESS TO THE SOUTH AND TRANSITION NORTHERN AREAS TO MAINLY SNOW DURING THE AFTERNOON...WITH AREAS ALONG THE INTERSTATE 70 CORRIDOR STARTING TO GET A WINTRY MIX...BUT RAIN HOLDING ON ACROSS FAR SOUTHERN AREAS THROUGH THE DURATION OF MONDAY AFTERNOON. BY LATE MONDAY EVENING...ALL AREAS SHOULD BE TRANSITIONING TO ALL SNOW. POINT SOUNDINGS DO NOT INDICATE LONG PERIODS OF ICE ACCUMULATIONS. THEY SHOW MORE OF A QUICK TRANSITION FROM RAIN TO SNOW ACROSS THE SOUTHERN HALF OF THE FORECAST AREA WITH ONLY A FEW HOUR TRANSITION PERIOD WHERE AN ICY MIX IS POSSIBLE. KEPT THE STORM TOTAL SNOW GRIDS AS IS SINCE IT DEPICTED THE HEAVIEST SNOW ACROSS FAR NORTHERN MISSOURI...AND WAS SIMILAR TO THE HPC GUIDANCE. LATER SHIFTS MAY NEED TO BUMP UP TOTALS FURTHER...AS CROSS- SECTIONS SHOW A NICE BULLSEYE OF LIFT WITHIN THE BEST TEMPERATURES FOR DENDRITIC ICE CRYSTAL GROWTH MONDAY AFTERNOON. IN ADDITION...THERE LOOKS TO BE PLENTY OF MOISTURE AS MIXING RATIOS ARE IN THE 3 TO 4 G/KG RANGE. WITH CONCERNS REGARDING PRECIP TYPE...DECIDED TO HOLD OFF ON UPPING TOTALS YET. FORECAST SNOW TOTALS ARE FOR AROUND 4 TO 6 INCHES ACROSS OUR NORTHERN 2 OR 3 TIERS OF COUNTIES WITH AMOUNTS LOWERING TO AN INCH OR TWO OVER FAR SOUTHERN AREAS BY THE TIME THE SNOW TAPERS OFF TUESDAY MORNING. WENT AHEAD AN HOISTED A WINTER STORM WATCH ACROSS FAR NORTHERN MISSOURI FROM 12Z MONDAY TO 12Z TUESDAY. THIS AREA STANDS THE BEST CHANCE OF GETTING COLD ENOUGH FOR HEAVIER SNOW...AND AS MENTIONED BEFORE WILL EXPERIENCE THE BETTER MID-LEVEL FORCING. IF COLDER AIR FILTERS IN FASTER THAN CURRENTLY EXPECTED...THIS WATCH MAY NEED TO BE EXPANDED SOUTHWARD. IN ADDITION TO THE SNOW...WINDS WILL INCREASE CAUSING BLOWING AND DRIFTING SNOW MONDAY NIGHT AS THE PRESSURE GRADIENT INCREASES WITH THE SURFACE LOW PASSING TO THE SOUTH. MADE NO OTHER CHANGES TO THE EXTENDED GRIDS. SAW && .EAX WATCHES/WARNINGS/ADVISORIES... MO...WINTER STORM WATCH FROM 6 AM MONDAY TO 12 PM TUESDAY FOR MOZ001-MOZ002-MOZ003-MOZ004-MOZ005-MOZ006-MOZ007-MOZ008-MOZ011- MOZ012-MOZ013-MOZ014-MOZ015-MOZ016-MOZ017. KS...NONE. $$ WFO EAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 930 AM EST MON FEB 12 2007 .UPDATE... LATEST SURFACE ANALYSIS PLACES SURFACE TROUGH EXTENDING FROM THE YUCATAN PENINSULA ACROSS THE FLORIDA STRAITS JUST SOUTH OF THE KEYS NE ALONG THE GULF STREAM EAST OF THE SE FLORIDA COAST AND INTO THE NW BAHAMAS. AT THE UPPER LEVELS...12Z ANALYSIS SHOWS AXIS OF UPR LVL JET MAX ACROSS CWA WITH RIGHT REAR QUADRANT RIGHT ABOVE THE SURFACE TROUGH ACROSS THE STRAITS. THE ANALYSIS ALSO SHOWS A NEGATIVELY TILTED S/W TROUGH JUST DUE NORTH OF THE YUCATAN PENINSULA ACROSS THE CENTRAL GULF OF MEXICO AT THIS TIME WITH PLENTY OF DIVERGENCE TO ITS EAST NORTHEAST ALOFT. HOWEVER...WATER VAPOR LOOPS OVER PAST FEW HOURS HAVE BEEN SHOWING THE AXIS OF THE S/W BECOMING LESS NEGATIVELY TILTED AND ONE WOULD EXPECT UPR LVL DIV TO DECREASE WITH THAT IF THAT TREND CONTINUES. FOR THE TIME BEING HOWEVER, THERE IS ENOUGH TO SUPPORT LARGE SCALE ASCENT FOR CONVECTION...EVEN STRONG CONVECTION LIKE IT IS HAPPENING ACROSS THE KEYS. WHEN LOOKING AT THE CONVECTIVE PARAMETERS ONE CAN SEE THE LIMITING FACTOR AT THIS TIME AND THAT IS LIMITED CAPE (LESS THAN 1000) WITH TEMP PROFILES THAT LOOK VERY CLOSE TO MOIST ADIABATIC A RESULT OF THE LOW LEVEL MOIST AIR ADVECTION THAT HAS BEEN TAKING PLACE SINCE YESTERDAY AND THE EXTENSIVE CLOUD COVER. THIS IS DESPITE MODIFIED AFTERNOON LI`S OF AROUND -4. NOW...THE QUESTION IS WHAT HAPPENS FROM THIS POINT ON. THIS IS WHERE YOU GO ON A LIMB DUE TO THAT DATA HOLE THAT IS THE GULF OF MEXICO. THERE COULD BE...ARGUABLY A WEAK SFC LOW TRYING TO DEVELOP SOMEWHERE AROUND THE YUCATAN PENINSULA BUT IT IS HARD TO FIND EVEN VIA HAND ANALYSIS. THIS IS PERHAPS WHAT GFS IS LATCHING ON TO WHICH IT DEVELOPS RATHER AGGRESSIVELY AS THE DAY PROGRESSES IN RESPONSE TO UPR LVL S/W FORCING. IF THIS HAPPENS, THEN THERE IS NO DOUBT SFC TROUGH TO OUR SOUTH SHOULD LIFT NORTH AS THE LOW AND UPR LVL S/W APPROACHES WEST CENTRAL AND SW FLORIDA TONIGHT INCREASING SEVERE WEATHER THREAT ACROSS THE AREA. ON THE OTHER HAND...THE NAM12 ...LOCAL WRF...AND RUC DO NOT QUITE BUY THIS SCENARIO AND KEEP THE SFC TROUGH EITHER TO OUR SOUTH OR MEANDERING ACROSS SOUTHERN PORTIONS OF CWA. THIS WOULD KEEP ANY POSSIBILITY OF SEVERE WEATHER CONFINED TO OUR SOUTH AND EXTREME ESE FLORIDA COAST. AT THIS TIME HAVE OPTED TO MENTION POSSIBILITY OF SEVERE WEATHER IN HWO OVER NEXT FEW HOURS IN GULF STREAM WATERS SE OF BISCAYNE BAY AND ACROSS THE OFFSHORE WATERS OF COLLIER AND MAINLAND MONROE COUNTIES WITH THE POSSIBILITY OF SEVERE WEATHER ACROSS THE REMAINDER OF THE AREA LATER THIS AFTERNOON INTO THE EVENING IF THE SFC TROUGH LIFTS NORTH AND THERE ARE ENOUGH BREAKS IN THE CLOUD TO OVERCOME LACK OF CONVECTIVE INSTABILITY (AND THERE ARE SOME). RIGHT NOW THERE IS TOO MUCH SHEAR FOR THE AMOUNT OF CAPE AVAILABLE AND THIS IS REFLECTED WELL IN THE NAM12 AND RUC40 BRN EXCEPT FOR THE GFS40 WHICH SHOWS BRN TYPICAL OF SUPERCELL ENVIRONMENTS. AT THIS TIME THE PRUDENT THING TO DO IS KEEP TALKING ABOUT THE POTENTIAL...WHICH CERTAINLY EXISTS... BUT KEEP IT AT THAT UNTIL TRENDS IN THE DATA BEGINS TO FAVOR THE GFS SOLUTION. HWO WILL BE UPDATED AS NEEDED DURING THE DAY. OTHER THAN THAT WILL TAPER DOWN THE 100 POPS TO 80 TO KEEP IT CATEGORICAL AS IT IS EVIDENT IT WILL NOT BE RAINING ALL DAY LONG BUT CERTAINLY MOST OF THE DAY. OTHER THAN THAT CURRENT FCST LOOKS ON TRACK. DESPITE SEVERE WEATHER OR NOT...THERE IS A CHC OF TSTMS EVERYWHERE AS S/W TROUGH APPROACHES THE AREA LATER TODAY. .DISCUSSION... A VERY PRONOUNCED MID-LEVEL CIRCULATION -- SEEN ON WATER VAPOR ANIMATION OVER THE CENTRAL GULF JUST NORTH OF YUCATAN THIS MORNING -- WILL HAVE THE MOST SIGNIFICANT IMPACT ON SOUTH FLORIDA FOR THE NEXT 24 HOURS. THE SATELLITE DEPICTION OF THIS FEATURE SUGGESTS THAT IT IS LIKELY STRONGER THAN ANY OF THE AVAILABLE MODEL GUIDANCE WOULD INDICATE...WITH THE GFS SOLUTION PROBABLY CLOSEST TO REALITY. WIDESPREAD AREAS OF LIGHT RAIN CONTINUE TO MOVE NORTHWARD OVER THE PENINSULA IN RAPIDLY STRENGTHENING WARM ADVECTION PATTERN SEEN IN AREA VWP DATA. BOTH AREAL COVERAGE AND INTENSITY OF RAINFALL IS EXPECTED TO INCREASE THROUGH THE MORNING HOURS...AND WILL CONTINUE WITH CATEGORICAL POPS FOR THE ENTIRE FORECAST AREA. AT THE SURFACE...A WEAK WARM FRONT WILL ATTEMPT TO MOVE NORTHWARD ACROSS THE AREA DURING THE DAY...WITH THE NORTHWARD MOTION LIKELY IMPEDED BY DIABATIC COOLING EFFECTS ACROSS NORTHERN PORTION OF THE AREA. IF THIS BOUNDARY INDEED BISECTS THE REGION THIS AFTERNOON...ALLOWING THE TROPICAL WARM SECTOR AIRMASS TO SPREAD NORTH ACROSS THE SOUTHERN HALF OF THE PENINSULA...THE THREAT OF SEVERE THUNDERSTORMS WILL INCREASE SUBSTANTIALLY GIVEN PRESENCE OF STRONG DIFFERENTIAL PVA OVER THE AREA AND LONG HODOGRAPHS PROGGED BY MODEL SOUNDINGS. THE UPPER TROUGH AXIS STILL APPEARS AS IF IT WILL GRADUALLY SHIFT EASTWARD ACROSS THE AREA OVERNIGHT...WITH THE APPROACH OF A STRONGER SYSTEM OVER THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY REGION. EXPECT SHOWERS/THUNDERSTORMS TO SLOWLY DIMINISH FROM SOUTHWEST TO NORTHEAST AS THIS OCCURS...WITH THE MOST CONCENTRATED RAINFALL SHIFTING NORTHEASTWARD INTO CENTRAL FLORIDA AND EASTWARD OFF THE ATLANTIC COAST OVERNIGHT. LOW-LEVEL WINDS WILL VEER TO THE SOUTHWEST ON TUESDAY MORNING...AS UPPER TROUGH MOVES AWAY FROM THE AREA AND WESTERLY FLOW JUST OFF THE SURFACE BEGINS TO MIX DOWNWARD. THIS WILL LIMIT CONVERGENCE AND THE COVERAGE OF SHOWERS/STORMS ON TUESDAY...BUT WILL LEAVE LOW CHANCE POPS IN FOR THE ENTIRE AREA GIVEN PRESENCE OF RESIDUAL LOW-LEVEL MOISTURE AND PASSAGE OF YET ANOTHER UPPER SHORTWAVE. RAIN CHANCES WILL END FOR THE ENTIRE AREA BY EARLY WEDNESDAY MORNING. IN THE EXTENDED FORECAST...MODELS ARE COMING INTO BETTER AGREEMENT ON TIMING OF FRONTAL PASSAGE ON WEDNESDAY...WITH THE GFS SOLUTION CLOSELY MATCHED WITH THE UKMET/ECMWF/CMC SUITE IN INDICATING FRONTAL PASSAGE ACROSS THE NORTHWEST COUNTIES BY EARLY AFTERNOON...AND ACROSS THE SOUTHEAST BY EARLY TO MID EVENING. WITH WESTERLY FLOW IN PLACE...EXPECT WEDNESDAY TO BE VERY WARM FOR ALL LOCATIONS... BUT THIS WILL BE THE LAST WARM DAY FOR QUITE AWHILE AS UPPER LOW AND ASSOCIATED SURFACE CYCLONE UNDERGO RAPID DEEPENING OVER THE NORTHEASTERN STATES...ALLOWING A VERY COLD ARCTIC AIRMASS TO COME CRASHING SOUTHWARD ACROSS THE CENTRAL/EASTERN CONUS. THERE IS STILL A SIGNAL FOR SOME LIGHT RAINFALL ON THURSDAY NIGHT AND FRIDAY...BUT THE GREATEST CONCERN IN THE EXTENDED FORECAST IS THE POTENTIAL FOR A FREEZE ACROSS AT LEAST A PORTION OF THE AREA ON SATURDAY MORNING. WILL CONTINUE TO TREND TEMPERATURES COLDER THAN ANY AVAILABLE GUIDANCE...WITH FORECASTED POSITION OF SURFACE HIGH ALLOWING FOR A GOOD NORTHERLY FETCH DOWN THE PENINSULA. && .AVIATION... OVERCAST SKIES WITH PERIODS OF LIGHT TO MODERATE RAIN EXPECTED TO CONTINUE AT ALL TERMINALS INTO THE MORNING HOURS TODAY AS COPIOUS AMOUNTS OF MOISTURE STREAM NORTHWARD...HOWEVER CEILINGS/VSBYS SHOULD ONLY DROP BELOW VFR LEVELS IN HEAVIER RAINFALL...WHICH MAY BE STEADY FOR A WHILE EARLY TOMORROW MORNING AT THE EAST COAST TERMINALS. FORECAST FOR TOMORROW IS UNCERTAIN IN REGARDS TO HOW MANY BREAKS IN THE CLOUDS WILL BE POSSIBLE...BUT DEFINITELY A BETTER CHANCE FOR A FEW BREAKS AT SOUTHERN TERMINALS KMIA AND KTMB BY MID DAY. FOR NOW HAVE GONE WITH VICINITY THUNDER THIS AFTERNOON AT ALL TERMINALS AS INSTABILITY AND MOISTURE INCREASE SOMEWHAT. && .MARINE... NO IMMEDIATE CONCERNS. HOWEVER...WITH LOW-LEVEL FLOW VEERING TO WESTERLY ON TUESDAY...AN INCREASED THREAT OF RIP CURRENTS ALONG THE GULF COAST CAN BE EXPECTED. OTHERWISE...GULF STREAM SEAS WILL SLOWLY RESPOND TO STRONGER WINDS BY APPROACHING ADVISORY CRITERIA ON WEDNESDAY. SEAS SHOULD EXCEED ADVISORY CRITERIA BEGINNING ON THURSDAY AS STRONG NORTHWEST WINDS SPREAD SOUTHWARD BEHIND A COLD FRONT. && .FIRE WEATHER... NO IMMEDIATE CONCERNS. HOWEVER...MODELS CONTINUE TO INDICATE POTENTIALLY DANGEROUS FIRE WEATHER CRITERIA BEING REACHED ONCE AGAIN TOWARD THE END OF THE WEEK...AS A DRY ARCTIC AIRMASS SPREADS ACROSS THE AREA. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 74 70 81 66 / + 90 40 20 FORT LAUDERDALE 76 71 82 67 / + 90 40 20 MIAMI 75 71 82 68 / + 70 30 20 NAPLES 75 67 78 68 / + 70 30 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ LONG TERM...70/DD SHORT TERM/AVIATION...65/GS fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 935 AM EST MON FEB 12 2007 .SHORT TERM /REST OF TODAY/... GIVEN THE DEPTH AND OPACITY OF THE MID CLOUD LAYER THIS MORNING AND PERHAPS SOME OROGRAPHIC ENHANCEMENT IN THE FAST WESTERLY FLOW ALOFT... SKY COVER WILL BE INCREASED FOR TODAY THOUGH SOME BREAKS ARE EXPECTED THIS AFTERNOON. THIS WILL SLOW TEMPERATURE RISE AS ALREADY BEING OBSERVED COMPARED TO PREVIOUS FORECASTS. MAX READINGS WILL BE REDUCED 2-3 DEGREES AS SUPPORTED BY THE NEWEST RUC AND WRF. -RFG && .PREV DISCUSSION... /ISSUED 315 AM EST MON FEB 12 2007/ SHORT TERM /TODAY THROUGH WEDNESDAY/... HIGH PRESSURE OVER THE AREA WILL DRIFT TO THE EAST...ALLOWING WINDS TO SHIFT TO THE SOUTHEAST ADVECTING MOISTURE INTO THE REGION. A LOW PRESSURE AREA OVER CENTRAL TEXAS WILL ADVANCE EAST TONIGHT. AS THIS SYSTEM APPROACHES AND MOISTURE ABOUNDS... THE CHANCE FOR RAIN WILL INCREASE OVERNIGHT THROUGH EARLY TUESDAY MORNING. THE TEXAS LOW WILL MOVES THROUGH THE TENNESSEE VALLEY TUESDAY AFTERNOON... WHILE A COASTAL LOW DEVELOPS ALONG THE CAROLINAS. THESE TWO SYSTEM WILL MERGE INTO A SINGLE LOW OVER DELMARVA WEDNESDAY MORNING. THUS THE CHANCE FOR RAIN WILL CONTINUE THROUGH MIDWEEK. RAIN WILL TAPER OFF AND END FROM THE WEST WEDNESDAY AFTERNOON. AT THE PRESENT TIME IT LOOKS LIKE THE MOISTURE WILL RETREAT WEDNESDAY BEFORE THE COLD AIR BUILDS ACROSS THE AREA. HIGHS TODAY MID 50S NW TO LOWER 60S SE... COOLING TO MID 30S NW TO MID 409S SE BY WEDNESDAY. LOWS UPPER 30S TO LOWER 40S TONIGHT... DROPPING TO LOWER 30S NW TO AROUND 40 SE BY TUESDAY NIGHT. LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... HIGH PRESSURE WILL BUILD INTO THE REGION WEDNESDAY NIGHT THROUGH FRIDAY NIGHT. NORTHERLY FLOW WILL KEEP US BELOW NORMAL ON TEMPERATURES. AS A FRONTAL SYSTEM DEVELOPS FROM THE THE GREAT LAKES TO CENTRAL TEXAS SATURDAY... HIGH PRESSURE OVER THE GULF OF MEXICO WILL ALLOW WINDS TO BECOME SOUTHWEST TO WEST. THIS WILL RESULT IN A SLOW WARMING TREND AS HIGHS REACH INTO THE 40S SATURDAY... AND THE UPPER 40S TO LOWER 50S SUNDAY. IT WILL REMAIN DRY THROUGH THE EXTENDED. AVIATION /06Z-06Z/... UPPER LEVEL WINDS WILL SPREAD HIGH AND MID CLOUDS INTO CENTRAL NORTH CAROLINA OVERNIGHT AND INTO EARLY MONDAY MORNING. CLOUD BASES SHOULD BE AT OR ABOVE 12000 FEET THROUGH 13Z. CLOUD BASES WILL GRADUALLY LOWER TO BETWEEN FIVE AND TEN THOUSAND FEET BY EARLY MONDAY AFTERNOON AS THE AIR MASS GRADUALLY GAINS MOISTURE IN INCREASING SOUTHWEST FLOW IN THE MID LEVEL FLOW. BY LATE MONDAY AFTERNOON OR EVENING...CLOUD BASES CONTINUE TO LOWER TO NEAR MVFR CEILINGS AS COLUMNS CONTINUES TO MOISTEN. DOES NOT APPEAR TO BE ENOUGH LIFT TO GENERATE ANYTHING MORE THAN CLOUDS (NO PRECIPITATION) THROUGH 06Z TUESDAY. PRETTY DECENT DIRECTIONAL AND SPEED SHEAR PROJECTED FOR TUESDAY AFTERNOON AND EVENING. LOW LEVEL WIND SHEAR MAY NEED TO BE INTRODUCED IN LATER TAF ISSUANCE. -WSS/RLH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RFG nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 215 PM CST MON FEB 12 2007 .DISCUSSION... SNOW AND ANOTHER ROUND OF ARCTIC AIR MAIN FOCUS IN THE SHORT TERM. REGIONAL RADARS SHOWING TWO AREAS OF PRECIP MOVING TOWARD THE CWA AT 19Z. ONE ACROSS CENTRAL NEBRASKA ASSOCIATED WITH MID LEVEL SHORT WAVE AND THE SECOND OVER KANSAS ASSOCIATED WITH ISENTROPIC LIFT AHEAD OF SOUTHERN PLAINS SURFACE LOW. SNOW EXPECTED TO DEVELOP AND OVERSPREAD THE AREA BY LATE AFTERNOON AS VERTICAL MOTION FIELD INCREASES WITH THE APPROACHING SHORT WAVE. 18Z RUC LIMITS ISENTROPIC FORCING TO ALONG AND SOUTH OF THE NEBRASKA KANSAS BORDER DURING THE AFTERNOON AND WITH CURRENT SURFACE TEMPERATURES IN THE MID 30S A PERIOD OF MIXED RAIN SLEET AND SNOW LIKELY BEFORE CHANGING TO ALL SNOW BY EVENING THERE IN THE SOUTHERN PART OF THE CWA AS DYNAMIC COOLING AND COLDER SURFACE AIR COMBINE TO DROP TEMPERATURES IN THE LOWER LAYERS. SNOW ADVISORY CHANGED TO WINTER WEATHER ADVISORY EARLIER AND WILL CONTINUE THAT HEADLINE FOR THIS FORECAST. LATEST INDICATIONS STILL LOOKING FOR 3 TO 5 INCH SNOWFALL ACROSS THE AREA BY TUESDAY MORNING WITH MAIN PERIOD OF ACCUMULATION EXPECTED THIS EVENING THROUGH ABOUT MIDNIGHT. ARCTIC AIR FOLLOWS BEHIND THIS SYSTEM ON TUESDAY WITH VERY COLD TEMPERATURES ACROSS THE REGION THROUGH THURSDAY AS HIGH CENTER DROPS SOUTH INTO THE CENTRAL PLAINS. CONTINUED TO TREND TEMPERATURES TOWARD THE COLDER GFS WITH COLDEST READINGS EXPECTED THURSDAY MORNING AS CENTER OF THE HIGH SETTLES ACROSS THE AREA. IN THE EXTENDED RETURN FLOW SETS UP BY THE BEGINNING OF THE PERIOD AS SFC HI PRES SHIFTS SEWD INTO MISSOURI AND ARKANSAS. THIS SHOULD GIVE US A QUICK WARM UP AS STRONG WARM AIR ADVECTION MOVES IN. NORTHWESTERLY FLOW ALOFT CONTINUES AND A SHORTWAVE TROF AND ITS ASSOCIATED SFC LOW PUSH THRU THE NRN PLAINS THRU THE DAY FRIDAY. SFC COLD FRONT PUSHES INTO THE FORECAST AREA BY FRIDAY NIGHT AND MODELS HAVE BEEN FAIRLY CONSISTENT AT THIS SO WILL INCREASE TO CHANCE POPS FOR SNOW. WL COOL DOWN BRIEFLY ON SATURDAY BEFORE A MUCH STRONGER WARM PUSH ON SUNDAY AND MONDAY. HIGHS IN THE 40S QUITE POSSIBLE BY MONDAY. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM CST TUESDAY FOR NEZ015-034-045-052-053-067-068-090>093. WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR NEZ011-012- 016>018-030>033-042>044-050-051-065-066-078-088-089. IA...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM CST TUESDAY FOR IAZ043-055-056-069-079-080-090-091. && $$ FOBERT/GRIFFIS ne