AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1006 PM EST FRI NOV 23 2007 .SYNOPSIS... A LARGE RIDGE OF HIGH PRESSURE WILL BUILD INTO OUR REGION FROM THE OHIO VALLEY TONIGHT BRINGING AN END TO THE LAKE EFFECT ACTIVITY OFF OF LAKE ONTARIO. A WARM FRONT LIFTING THROUGH THE UPPER GREAT LAKES LATE SATURDAY INTO SATURDAY NIGHT MAY BRING A LITTLE LIGHT SNOW TO THE SOUTHERN ADIRONDACKS SATURDAY NIGHT. MORE SEASONABLE WEATHER WILL FOLLOW ON SUNDAY AS HIGH PRESSURE RETURNS TO THE REGION. ON MONDAY A STORM SYSTEM WILL LIFT NORTHEAST FROM THE TENNESSEE VALLEY INTO THE EASTERN GREAT LAKES BRINGING MAINLY RAIN TO OUR REGION. && .NEAR TERM /THROUGH SATURDAY/... LAKE EFFECT ACTIVITY CONTINUING AND NOSING INTO CAPITOL REGION AND BERKSHIRES. RUC ANALYSIS SHOWS WEAK SHORTWAVE SWINGING THROUGH IN NORTHWEST FLOW. UPDATED CLOUDS/POPS/WEATHER BASED ON SATELLITE AND RADAR TRENDS. LOOKS LIKE SNOW SHOWERS WILL GRADUALLY DIMINISH OVERNIGHT AFTER TROUGH SWINGS THROUGH. ON SATURDAY TEMPS WILL STRUGGLE TO REACH THE FREEZING MARK NORTH AND IN THE MOUNTAINS WITH HIGHS MAINLY 35 TO 40 SOUTH AS 850MB TEMPS AVERAGE ABOUT -10C ACROSS AREA. CLOUDS ARE ALSO EXPECTED TO INCREASE DURING THE AFTERNOON ACROSS THE SOUTHERN ADIRONDACKS AHEAD OF A WARM FRONT LIFTING THROUGH THE UPPER GREAT LAKES REGION. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... WHILE MOST AREAS EXPECTED TO BE DRY SATURDAY NIGHT...NORTHWEST ZONES WILL HAVE A CHANCE OF LIGHT SNOW IN ADVANCE OF AFOREMENTIONED WARM FRONT. TEMPS WILL BE TRICKY ON SATURDAY NIGHT...BUT TEMPS ARE EXPECTED TO DROP LATE ACROSS SOUTHERN TWO THIRDS OF FA AS CLOUDS DIMINISH. EXPECT A SIGNIFICANT MODERATING TREND ON SUNDAY AS WARM FRONT LIFTS WELL NORTHEAST OF FA. H8 TEMPS EXPECTED TO BE 3-5C WARMER THAN SATURDAY WITH H10-H5 THICKNESS VALUES RISING FROM 522-531 DECAMETERS SATURDAY EVENING TO 537-543 DECAMETERS SUNDAY EVENING...THUS EXPECTING TEMPS SUNDAY AFTERNOON 8-10F WARMER ON SUNDAY THAN SATURDAY. AT THIS POINT IN TIME IT LOOKS AS IF PCPN WILL HOLD OFF UNTIL VERY LATE SUNDAY NIGHT OR INTO MONDAY AND THIS TIMING WILL BE CRITICAL TO PCPN TYPE. BASED ON PARTIAL THICKNESS VALUES AND MODEL SOUNDINGS...IF PCPN ARRIVES BEFORE DAYBREAK ON MONDAY PTYPE WILL LIKELY BE FREEZING RAIN. CURRENTLY GOING WITH SLIGHT CHANCE TO CHANCE POPS LATE SUNDAY NIGHT SOUTH OF MOHAWK VALLEY AND WILL INCLUDE MENTION OF THIS IN HWO. && .LONG TERM /MONDAY THROUGH THURSDAY/... ON MONDAY...THE 850 TROF WITH ITS CLOSED LOW OVER SOUTHERN MISSOURI BEGINS TO FILL AND LIFTS NORTHEAST TOWARD THE GREAT LAKES. THE SURFACE LOW MOVES FROM WESTERN TENNESSEE TO THE GREAT LAKES BRINGING A LOW LEVEL JET OF 50 TO 55 KNOTS ALONG THE APPALACHIANS BRINGING WARM AND MOIST AIR FROM THE SOUTH EASTERN STATES INTO THE REGION OVER THE COLDER AIR REMAINING FROM THE HIGH THE PAST WEEKEND. THERE IS SOME QUESTION OF WHEN PRECIPITATION WILL BEGIN AS IF IT STARTS EARLY ENOUGH IT COULD BEGIN AS FREEZING RAIN WITH 925-850 TEMPERATURES PLUS 2 HERE AT ALBANY. WE WILL CONTINUE THE PREVIOUS FORECAST OF SLIGHT CHANCE OF FREEZING RAIN FOR EARLY MONDAY...TURNING TO ALL RAIN BY LATE MORNING...WITH TEMPERATURES CLIMBING FROM OVERNIGHT LOWS IN THE 20S TO HIGHS FROM THE UPPER 30S TO THE MID 40S. THE LOW MOVES TO LAKE ERIE BY MONDAY EVENING AND UP THE SAINT LAWRENCE VALLEY MONDAY NIGHT INTO SOUTH EASTERN QUEBEC BY TUESDAY MORNING AND IT CONTINUES TO LIFT NORTHEAST. AS IT LIFTS OUT DRIER AIR WILL BE BROUGHT IN FROM THE NATION/S MIDSECTION AROUND THE NORTH SIDE OF A HIGH WHICH WILL BUILD INTO THE MID ATLANTIC STATES. THIS HIGH WILL DOMINATE OUR WEATHER TUESDAY AND THE FIRST PART OF WEDNESDAY BEFORE ANOTHER LOW MOVES FROM THE MISSISSIPPI VALLEY TO THE GREAT LAKES AND UP THE ST LAWRENCE VALLEY THURSDAY. IT CONTINUES INTO THE MARITIMES AS ANOTHER HIGH BUILDS OVER THE REGION TO DOMINATE OUR WEATHER FRIDAY. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... WITH HIGH PRESSURE BUILDING IN...TAF SITES WILL REMAIN VFR THROUGH 00Z SUNDAY. A FEW LIGHT SNOW FLURRIES POSSIBLE AT KALB THIS EVENING ALONG WITH A BROKEN CEILING AROUND 3500FT. LAKE EFFECT SNOW SHOWERS WITH MVFR CIG/VIS WILL CONTINUE THROUGH ABOUT MIDNIGHT OVER THE MOHAWK VALLEY AND THE SOUTHWESTERN ADIRONDACKS. TOO COLD AND DRY FOR NIGHTTIME FOG. WINDS WILL GRADUALLY DIE OUT THIS EVENING AND STAY LOW ON SATURDAY AS THE HIGH SETTLES IN. SATURDAY MAINLY CLEAR EARLY...WITH HIGH CLOUDS INCREASING LATE IN THE DAY AS A WARM FRONT APPROACHES. SOME LIGHT SNOW POSSIBLE EARLY SUNDAY MORNING KGFL AND NORTH. OUTLOOK... SAT TO SUN NIGHT...VFR EXCEPT POSSIBLE MVFR KGFL AND NORTH IN LIGHT SNOW EARLY SUNDAY MORNING. MON TO TUE...VFR BECOMING MVFR/IFR WITH RAIN MOVING IN. TUE NIGHT TO WED...BACK TO VFR. && .HYDROLOGY... THE HEAVY RAIN THAT HAD BEEN FORECAST FOR THE UPPER MOHAWK BASIN OVER THE HOLIDAY REMAINED NORTH...SO THE RIVER AT UTICA WILL REMAIN CLOSE TO THE 400 FOOT ELEVATION TODAY AND THEN GRADUALLY RECEDE ABOUT A FOOT OVER THE NEXT TWO DAYS. A RELEASE OF JUST UNDER 1000 CUBIC FEET PER SECOND CONTINUES OUT OF LAKE DELTA TO LOWER THE LAKE LEVEL. THE MOOSE RIVER CRESTED A LITTLE OVER 6 FEET AT MCKEEVER AND IT WILL RECEDE ABOUT TWO FEET OVER THE NEXT TWO TO THREE DAYS. THE RAIN ALSO CAUSED THE HUDSON RIVER AT NORTH CREEK TO RISE ABOUT A FOOT SINCE WEDNESDAY EVENING. IT WAS CRESTING THERE THIS MORNING AND IT WILL CREST A LITTLE OVER 5 FEET AT HADLEY THIS EVENING. A RELEASE OF 4100 CFS WILL CONTINUE FROM GREAT SACANDAGA LAKE. THIS WILL KEEP THE HUDSON RIVER UP SLIGHTLY BETWEEN CORINTH AND WATERFORD. MODEL GUIDANCE SUGGESTS WE COULD GET ONE TO ONE AND A HALF INCHES OF RAIN MONDAY AND MONDAY NIGHT...WHICH DEFINITELY BEARS WATCHING. THE STORM LATER NEXT WEEK COULD BRING ANOTHER HALF INCH TO AN INCH OF RAIN. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...11 NEAR TERM...SND SHORT TERM...11 LONG TERM...KILPATRICK AVIATION...SND HYDROLOGY...KILPATRICK ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1240 AM EST FRI NOV 23 2007 .SYNOPSIS... BEHIND A STRONG COLD FRONT...MUCH COLDER TEMPERATURES WILL FILTER INTO THE REGION FOR TONIGHT THROUGH THE WEEKEND...AS AN AREA OF CANADIAN HIGH PRESSURE MOVES ACROSS THE NORTHEAST. EARLY NEXT WEEK...ANOTHER STORM SYSTEM WILL MOVE THROUGH THE EASTERN GREAT LAKES...BRINGING A FEW ROUNDS OF PRECIPITATION THE AREA...AS THE STORM/S WARM FRONT AND COLD FRONT MOVE THROUGH THE REGION. && .NEAR TERM /TONIGHT AND FRIDAY/... AT 1800 UTC...THE 40KM RUC AND MSAS OBSERVATIONS SHOW LOW PRESSURE PASSING BETWEEN KRME AND KALB. THERE IS AN IMPRESSIVE FALL/RISE ISALLOBARIC PRESSURE COUPLET WITH THE SFC WAVE PASSING ALONG THE FRONTAL BOUNDARY. THE 3-HR PRESSURE RISES OVER W-CNTRL PA...ERN OH ...AND NRN WV ARE 5-6 HPA. LOCATIONS SOUTH AND EAST OF THE CAPITAL DISTRICT PUNCHED INTO THE WARM AIR...WITH TEMPS IN THE 50S AND 60S. KALB HAS STRUGGLED TO GET TO THE MID TO UPPER 40S. THE PCPN SHIELD HAS SHRUNK WITH THE FRONT/WAVE QUITE A BIT OVER THEN PAST FEW HOURS. THE BEST UPPER LEVEL JET STREAK AND DIVERGENCE WENT WELL N/NE INTO CANADA. UPSTATE NY IS IN THE UNFAVORABLE RIGHT FRONT QUAD/RIGHT EXIT REGION OF THE UPPER LEVEL JET. THE THERMAL GRADIENT IS STILL VERY STRONG WITH THE FRONT...WITH 850 MB TEMPS AHEAD OF THE BOUNDARY +10-+11C...AND WEST OF THE BOUNDARY -9C TO -10C OVER NEAR KBUF. WE SHOULD SEE THE CURRENT BAND OF SHRAS MOVE THROUGH THE CAPITAL REGION 20Z-22Z WITH AN ABRUPT WIND SHIFT TO THE WEST NORTHWEST. OVERNIGHT...EARLY ON THIS EVENING WE KEPT A SLIGHT CHANCE OF SHOWERS OVER THE E/SE PORTION OF THE FCST AREA UNTIL ABOUT 00Z. THE WINDS WILL CONTINUE TO BE BLUSTERY FROM THE W/NW AT 15-25 MPH WITH PERHAPS A FEW GUSTS GETTING CLOSE TO 40 MPH. THE SFC LOW SHOULD INTENSIFY AS IT MOVES NE ALONG THE ST LAWRENCE RIVER VALLEY. THE LOW LEVEL PRESSURE GRADIENT BETWEEN THE 1035 MB HIGH OVER THE SRN PLAINS AND A 995 HPA LOW EAST OF MAINE BY 12Z FRI WILL KEEP THE CHILLY NW FLOW IN PLACE. THE LAKE EFFECT SNOW OFF ONTARIO LOOKS TO BE OF THE MULTIBAND VARIETY...WITH A PREDOMINANT 310 DEGREE TRAJECTORY WITH MODERATE INSTABILITY. THE BEST CHANCES OF SHSNS WERE PLACED OVER SRN HERKIMER...SCHOHARIE...WRN GREENE AND WRN ULSTER COUNTIES. WE ARE EXPECTING A DUSTING TO AN INCH OR TWO. THERE MAY ALSO BE SOME WESTERLY UPSLOPE SHSNS OVER THE SRN GREENS AND WRN ADIRONDACKS EARLY ON...IN THE WAKE OF THE FRONT. WE KEPT SOME LOW CHANCE POPS THERE. THE STRONG COLD AIR ADVECTION ALLOWS H850 TEMPS TO FALL TO -10C TO -15C FROM SE TO NW ACROSS THE FCST AREA BY 1200 UTC. WE WENT CLOSE TO THE COLD GFSMOS TEMPS. FRIDAY...A BRISK AND COLD SHOPPING DAY LOOKS TO BE ON TAP. THE BUFKIT PROFILES FOR KSYR SHOW THE LOW LEVEL INVERSION DROP TO 5 KFT AROUND NOONTIME...WHICH SHOULD SQUASH ANY SUBSTANTIAL LAKE BANDS IMPACTING OUR FCST AREA. THE LOW LEVEL FLOW ALSO TURNS ANTICYCLONIC...AS HIGH PRESSURE NUDGES IN FROM THE OH VALLEY BY THE AFTERNOON. WE TAPERED POPS TO SLIGHT CHANCE VALUES. DOWNSLOPING OFF THE CATSKILLS AND ADIRONDACKS SHOULD YIELD PARTLY TO MOSTLY SUNNY SKIES OVER THE MID HUDSON VALLEY...AND CAPITAL DISTRICT. WE WENT A TAD COLDER THAN THE GFSMOS VALUES ON FRIDAY DUE TO THE FRIGID 850 MB TEMPS STILL IN THE -12C TO -15C RANGE WITH THE CORE OF COLDEST AIR ALOFT MOVING OVERHEAD. WIND CHILLS WILL RANGE FROM THE SINGLE DIGITS OVER THE ADIRONDACKS TO THE TEENS AND TWENTIES OVER THE REST OF THE REGION. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... SUBSIDENCE IN THE WAKE OF THE SHORT WAVE AND RISING SURFACE PRESSURES SHOULD PRECLUDE THE MENTION OF RESIDUAL PRECIP CHANCES AND LAKE ONTARIO CONTRIBUTIONS. IN FACT...THIS COULD BE QUITE A CHILLY NIGHT FOR THE REGION WITH A FAIRLY DRY ATMOSPHERIC COLUMN WITH CLEARING SKIES AND LIGHT WINDS. HAVE DECIDED TO GO AT OR JUST BELOW GUIDANCE WITH MAINLY TEENS IN THE VALLEY LOCATIONS AND SINGLE DIGITS FOR THE HIGHER ELEVATIONS AS 850MB TEMPS WILL BE AT OR BELOW -10C WHICH SEEMS TO BE THE NCEP MODEL SUITE CONSENSUS. SATURDAY... SURFACE RIDGE AXIS AND ALOFT WILL SLIDE TO OUR EAST SATURDAY AFTERNOON. MEANWHILE...A RATHER FAST MOVING IMPULSE WITHIN THE WESTERLIES WILL IMPACT THE REGION IN THE FORM OF HIGH AND MID LEVEL MOISTURE. BUFR SOUNDINGS FROM THE NAM/GFS REFLECT A RATHER HIGH DEWPOINT DEPRESSIONS BETWEEN 600-875MBS. THE EXCEPTION COULD BE OFF OF LAKE ONTARIO WITH FAVORABLE INSTABILITY AND TRAJECTORY ALONG WITH THIS AFOREMENTIONED WAVE COULD BRING A LITTLE LIGHT SNOW FOR PORTIONS OF HERKIMER COUNTY AND NORTHERN ADIRONDACKS. SUNSHINE WILL BECOME MORE FILTERED THROUGH THE DAY AND HOLD OFF THE INSOLATION WHICH SHOULD KEEP TEMPERATURES FROM RISING MUCH ABOVE THE MIDDLE 30S. SATURDAY NIGHT... THE WAVE DEPARTS OFF THE NORTHEAST COAST SATURDAY EVENING LEAVING BEHIND A RATHER CONFLUENT FLOW ACROSS THE GREAT LAKES REGION. THIS SHOULD PROVIDE A TRANQUIL NIGHT FOR THE REGION WITH PERHAPS A LITTLE ENTRANCE REGION DYNAMICS ACROSS THE ADIRONDACKS WITH A SLIGHT CHANCE FOR A LITTLE SNOW. SUNDAY... OUR EXTREME NORTHWEST CWA REMAINS RATHER CLOSE TO UPPER JET DYNAMICS AND INCREASING BAROCLINICITY SO WILL CONTINUE WITH THE VERY LOW POPS AT THIS TIME. OTHERWISE...BASED ON FORECAST MIXING LAYER HEIGHTS BETWEEN 850-900MB WE SHOULD TAP OUT INTO THE 40S FOR HIGH TEMPERATURES WITH A FAIR AMOUNT OF SUNSHINE. COULD SEE FAVORABLE DOWNSLOPING CONDITIONS FOR THE HUDSON VALLEY REGION SUNDAY AFTERNOON AS WELL WITH STRENGTHENING WEST-SOUTHWEST FLOW. SUNDAY NIGHT... THIS WILL BE A TRANSITIONAL PERIOD AS WE MONITOR THE UPPER WAVE NOW CROSSING NEVADA BECOMING NEARLY CUT OFF BEFORE BECOMING ENTRAINED WITHIN THE LONG WAVE TROUGH OVERNIGHT AS ADDITIONAL SHORT WAVE ENERGY DIVES SOUTHEAST OUT OF THE GULF OF ALASKA. THIS LEAVES THE CWA WITHIN A NULL REGION...AND WILL CONTINUE WITH THE NULL PRECIP FORECAST. SKY COVER WILL BE PROBLEMATIC BUT WILL FAVOR A MOCLR TO PTCLDY FORECAST. TEMPERATURES SHOULD BOTTOM OUT INTO THE MIDDLE 20S WITH PERHAPS WARMING A FEW DEGREES OVERNIGHT WITH SOME OF THOSE CLOUDS INCREASING FROM SOUTH TO NORTH. && .LONG TERM /MONDAY THROUGH THURSDAY/... ECMWF AND GFS ENSEMBLE ALONG WITH NAEFS ENSEMBLE MEAN SUPPORT THE MORE WESTWARD TRACK OF THE EJECTING SURFACE LOW FROM THE LOWER MISSISSIPPI RIVER VALLEY MONDAY-TUESDAY TIME FRAME AS HEIGHTS CONTINUE TO BUILD ACROSS BAHAMAS/FL/SOUTHEAST CONUS. WITH THE MJO ENTERING PHASE 8 AT THIS TIME...TELECONNECTION POINT TOWARD A MORE EASTERN CONUS RIDGING AND A WELL AGREED UPON HEIGHT RISE ALONG THE MID AND SE COAST SHOULD HAVE THIS LOW TRACK ALONG OR WEST OF THE REGION. THE MIXED PRECIP POTENTIAL IS STILL THERE BUT IT SEEMS TO BE DIMINISHING WITH A FURTHER WEST TRACK OF THE EXPECTED CYCLONE. IN THE WAKE OF THIS SYSTEM...THE COLD ADVECTION MAY NOT HAVE A HUGE IMPACT AS PREVIOUS RUNS WOULD INDICATE. HAVE REFLECTED THIS IDEA IN THE LATEST FORECAST/GRIDS WITH A WARMER SIDE OF THE GUIDANCE ENVELOPE AND REDUCE PRECIP CHANCES ACCORDINGLY. NEXT SYSTEM TO APPROACH AND IMPACT THE AREA ARRIVES LATE IN THE WEEK. CONSENSUS FAVORS A FURTHER WEST AND COINCIDING WARMER SOLUTION FOR THE REGION. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... LOW PRESSURE CONTINUES TO MOVE NORTHEAST INTO NEW BRUNSWICK. COLD AIR IN THE WAKE OF THE STRONG COLD FRONT THAT MOVED THROUGH YESTERDAY AFTERNOON CONTINUES TO FUNNEL INTO UPSTATE NY AND NEW ENGLAND. BLUSTERY NW WINDS WILL CONTINUE WITH VARIABLE CLOUDINESS DUE TO LAKE ENHANCED SHSNS AND FLURRIES AND THE APPROACH OF THE UPPER LEVEL TROUGH. VFR/MVFR CONDITIONS WILL PREVAIL PRIOR TO 12Z FRI. THE MVFR CONDITIONS WILL BE DUE TO CIGS IN THE 2-3 KFT AGL RANGE FROM TIME TO TIME FROM KALB NORTH TO KGFL. CIGS WILL GENERALLY BE BKN035-045 BTWN 12Z AND 22Z FRI. THE BIGGER TAF ISSUE WILL CONTINUE TO BE THE STRONG W/NW WINDS. THEY WILL CONTINUE TO BE 8-16 KTS WITH GUSTS IN THE 25-30 KT RANGE...ESPECIALLY AT KALB THIS MORNING. THE BRISK NW WINDS WILL CONTINUE AFTER 12Z FRI WITH 10-15 KTS AND A FEW GUSTS CLOSER TO 25 KTS. HIGH PRESSURE WILL BE BUILDING IN FROM THE OHIO VALLEY FRIDAY PM WITH THE SKIES CLEARING...AND THE WINDS DIMINISHING TO 5-10 KTS TOWARDS 00Z SAT. OUTLOOK... SAT TO MON PM...VFR. MON NIGHT-TUE...VFR BECOMING MVFR/IFR WITH RAIN MOVING IN. && .HYDROLOGY... NO HYDRO PROBLEMS ANTICIPATED. THE W-CNTRL MOHAWK VALLEY HAS RECEIVED LESS THAN A HALF AN INCH OF PRECIPITATION. THE MOHAWK RIVER VALLEY NEAR UTICA HAS RISEN VERY LITTLE AND NO PROBLEMS ARE EXPECTED. FURTHER NORTH ACROSS THE BLACK RIVER BASIN...UP TO AN INCH OF RAINFALL FELL. ANY ADDITIONAL PCPN WILL BE WITH THE FRONTAL PASSAGE LATE THIS PM/EARLY THIS EVENING. A COLD CANADIAN AIR MASS WILL BUILD IN FROM THE MIDWEST AND GREAT LAKES REGION FRIDAY THRU THE HOLIDAY WEEKEND WITH MAINLY DRY WEATHER. LOW PRESSURE WILL MOVE IN FROM THE SOUTH AND WEST LATE MON INTO TUESDAY WITH PERHAPS A MIX BAG OF PCPN CHANGING TO RAINFALL. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...FRUGIS NEAR TERM...TAW SHORT TERM...BGM LONG TERM...BGM AVIATION...TAW HYDROLOGY...TAW WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1237 PM EST THU NOV 22 2007 .SYNOPSIS... HAPPY THANKSGIVING. AN AREA OF LOW PRESSURE WILL MOVE EASTWARD ALONG A FRONTAL BOUNDARY DRAPED ACROSS NORTHERN NEW YORK. THE LOW WILL MOVE DIRECTLY OVER THE LOCAL AREA THIS AFTERNOON. AHEAD OF THE LOW AND TO THE SOUTH OF THE FRONTAL BOUNDARY THE WEATHER WILL BE VERY MILD. HOWEVER ONCE THE LOW MOVES OFF TO OUR EAST...A SHARP COLD FRONT WILL BE DRAGGED ACROSS THE AREA AND MUCH COLDER AIR WILL BE USHERED IN AND TEMPERATURES WILL TUMBLE. THE LOW WILL DEEPEN AS IT HEADS NORTHEAST TO THE CANADIAN MARITIMES TONIGHT. HIGH PRESSURE WILL BUILD IN ON FRIDAY AND DOMINATE OUR WEATHER SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... AT 15 UTC THE 40KM RUC SHOWS SFC LOW PRESSURE JUST SW OF KELM. A WARM FRONT IS RAPIDLY LIFTING N/NE AHEAD OF THE WARM FRONT. THE LATEST TEMPERATURE FROM THE HUDSON AWOS IN COLUMBIA IS 60F ! HERE AT KALB WE ARE SITTING AT 38F ! THE SHALLOW NATURE OF THE COLD AIR IS VERY EVIDENT ON THE 12Z KALB SOUNDING. WE ANTICIPATE A BRIEF JUMP UP IN TEMPERATURES TO THE LOWER TO MID 50S IN THE CAPITAL REGION...WITH MID 50S TO LOWER 60S OVER THE MID HUDSON VALLEY...TACONICS AND PORTIONS OF WRN NEW ENGLAND. WE TRIED TO ACCOUNT FOR THE TEMP TRENDS IN THE HOURLY TRENDS. WE DID CURTAIL ABOUT 3-5 DEGREES OFF THE PREV MAX TEMPS FROM THE CAPITAL REGION NORTH AND WEST...SINCE THE MINS AND SHALLOW NATURE OF THE COLD AIR WAS NOT CAPTURED WELL BY THE PREVIOUS MOS GUIDANCE. 850 MB TEMPS ARE A PALTRY +9-+11C IN ADVANCE OF THE SFC WAVE. WE DO NOT THINK THE MIXED PCPN WILL BE AN ISSUE OVER THE SRN ADIRONDACKS THE REST OF TODAY. TEMPS ARE GENERALLY IN THE 34-36F RANGE IN NORTHERN HERKIMER AND HAMILTON COUNTIES FROM SOME OF THE NERON OBS SITES /OLD FORGE...INDIAN LAKE...AND NORTH CREEK/. A FAIRLY SHARP TRANSITION TO SNOW SHOULD OCCUR IN THE LATE PM/EARLY PM WITH THE COLD FRONTAL PASSAGE. WE WE STILL KEPT LOW LIKELY POPS AS FAR SOUTH AS THE MID HUDSON VALLEY WITH THE FRONTAL PASSAGE. WE PLACED AN INCH OR SO OF SNOW OVER THE SRN ADIRONDACKS PRIOR TO 23Z. WE KEPT AN INCH OR SO IN OVERNIGHT WITH THE BRISK W/NW FLOW IN THE WAKE OF THE FRONTAL PASSAGE. SIGNIFICANT COLD AIR ADVECTION WILL BE ONGOING. THE PRESSURE RISES IN THE WAKE OF THE FRONT AND LOW PASSAGE ARE QUITE SIGNIFICANT OVER OHIO WITH 3 HR CHANGES IN EXCESS OF 6 HPA. ANY UPSLOPE SHSNS AND FLURRIES OFF THE SRN ADIRONDACKS AND SRN GREENS WILL BEGIN TO DWINDLE AROUND 06Z. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... RIDGE BUILDS IN FRIDAY AND PRESSURE GRADIENTS WEAKENS AS LOW MOVES FARTHER AWAY FROM REGION. UPPER TROUGH AXIS MOVES OFF TO OUR EAST IN THE AFTERNOON. NORTHWEST FLOW OF COLD AIR OVER LAKE ONTARIO WILL RESULT IN SOME LAKE ENHANCED SNOW SHOWERS FOR THE EASTERN CATSKILLS FRIDAY BUT CHANCES WILL DECREASE AS THE DAY PROGRESSES AND THE FLOW BECOMES MORE ANTICYCLONIC. THE SURFACE HIGH IS CENTERED WELL TO OUR SOUTH AND WILL SHIFT OFF THE MID ATLANTIC/SOUTHEAST COAST SATURDAY. ALOFT MEAN TROUGH WILL REMAIN OVER REGION. IT WILL BE COLD WITH HIGHS ONLY IN THE 30S WITH 20S ACROSS THE HIGHER TERRAIN BOTH FRIDAY AND SATURDAY. LOWS N THE TEENS FRIDAY NIGHT WITH SINGLE DIGITS ACROSS THE SOUTHERN ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... SHORT WAVE ZIPS THROUGH FLAT TROUGH OVER THE REGION SATURDAY NIGHT AND SUNDAY WITH LITTLE IMPACT EXPECTED TO AREA. MODELS CONTINUE TO SHOW SPLIT FLOW DEVELOPS AS UPPER LOW CUTS OFF OVER THE SOUTHWEST AND NORTHERN MEXICO THIS WEEKEND. A LOW PRESSURE WILL DEVELOP OVER THE SOUTH DEEP IN RESPONSE. THIS SYSTEM IS THEN EXPECTED TO HEAD NORTHEAST AND SHOULD IMPACT OUR REGION EARLY NEXT WEEK. THE DETAILS...TIMING AND TRACK...ARE UNCERTAININ. THE ECMWF AND GFS HAVE SOLUTIONS MORE SIMILAR THIS MORNING THAN YESTERDAY BUT STILL VERY DIFFERENT. THE ECMWF TRACKS THE SURFACE LOW UP THE MISSISSIPPI VALLEY TO THE GREAT LAKES REGION MONDAY INTO TUESDAY WITH THE GFS TRACK FARTHER TO EAST AND A BIT SLOWER. EITHER WAY THERE IS THE THREAT FOR A MIXED PRECIPITATION EVENT WITH FREEZING RAIN/SLEET IN OUR AREA MONDAY NIGHT INTO TUESDAY MORNING AS WARM AIR OVERRIDES COLD AIR AT THE SURFACE. WILL CONTINUE OT HIGHLIGHT THREAT IN THE HAZARDOUS WEATHER OUTLOOK. && .AVIATION /18Z THURSDAY THROUGH MONDAY/...LOW PRESSURE NEAR KBGM CONTINUES TO MOVE E/NE AT 17 UTC ALONG A FRONTAL BOUNDARY. THE WARM FRONT EAST OF THE LOW HAS MADE IT VERY CLOSE TO KALB. HOWEVER...IT DOES LOOK LIKE LLWS AND LIFR/IFR CIGS WILL PERSIST FOR A FEW MORE HOURS /AROUND 22Z/ UNTIL THE COLD FRONT MOVES THROUGH. WE ARE EXPECTING A FRONTAL PASSAGE IN THE 21Z-00Z TIME FRAME ACROSS ERN NY. THE CIGS AND VSBYS SHOULD BE PREDOMINANTLY HIGH MVFR/LOW VFR IN THE WAKE OF THE FRONTAL PASSAGE OVERNIGHT. THE WINDS WILL BE FROM THE W/NW AT 10-15 KTS WITH SOME GUST APPROACHING 25 KTS. THE WINDS MAY RELAX A LITTLE AFTER 05Z. AFTER 12Z FRI...SCT-BKN CIGS AT AROUND 4 KFT WITH BRISK NW WINDS 10-15 KTS WITH GUSTS AROUND 25 KTS WILL PREVAIL. OUTLOOK... FRIDAY...VFR/MVFR WITH LAKE EFFECT SNOW SHOWERS WEST OF THE HUDSON RIVER VALLEY. SAT...VFR. SUN-MON PM...VFR. MON NIGHT-TUE...VFR BECOMING IFR AS RAIN/SNOW/POSSIBLY FZRA MOVES IN. && .HYDROLOGY... NO HYDRO PROBLEMS ANTICIPATED. THE W-CNTRL MOHAWK VALLEY HAS RECEIVED LESS THAN A HALF AN INCH OF PRECIPITATION. THE MOHAWK RIVER VALLEY NEAR UTICA HAS RISEN VERY LITTLE AND NO PROBLEMS ARE EXPECTED. FURTHER NORTH ACROSS THE BLACK RIVER BASIN...UP TO AN INCH OF RAINFALL FELL. ANY ADDITIONAL PCPN WILL BE WITH THE FRONTAL PASSAGE LATE THIS PM/EARLY THIS EVENING. A COLD CANADIAN AIR MASS WILL BUILD IN FROM THE MIDWEST AND GREAT LAKES REGION FRIDAY THRU THE HOLIDAY WEEKEND WITH MAINLY DRY WEATHER. LOW PRESSURE WILL MOVE IN FROM THE SOUTH AND WEST LATE MON INTO TUESDAY WITH PERHAPS A MIX BAG OF PCPN CHANGING TO RAINFALL. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ NEAR TERM...TAW AVIATION...TAW HYDROLOGY...TAW ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 100 AM EST THU NOV 22 2007 .SYNOPSIS... A STRONG FRONTAL BOUNDARY WAS DRAPED ACROSS THE MID WEST...NORTHERN NEW YORK AND INTO NEW ENGLAND. SOUTH OF THIS BOUNDARY...MILD CONDITIONS PREVAIL WHICH WILL CONTINUE THROUGH THE FIRST HALF OF THE THANKSGIVING HOLIDAY. THEN A WAVE OF LOW PRESSURE ACROSS THE OHIO RIVER VALLEY WILL INTENSIFY AND TRACK ACROSS THE REGION BRINGING A SHARP COLD FRONT THROUGH THANKSGIVING AFTERNOON. WINDY AND COLDER WEATHER WILL PREVAIL THROUGH FRIDAY...WITH THOSE COLDER TEMPERATURES HOLDING ON THROUGH THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY/... WITH SOME PEAKS OF SUNSHINE AND PASSAGE OF THE WARM FRONT...TEMPS HAVE RISEN NICELY WELL INTO THE 40S AND LOWER 50S FROM THE CAPITAL REGION AND POINTS SOUTH. CURRENT H2O VAPOR LOOP ANALYSIS REVEALS A DIGGING SHORT WAVE INTO THE LONG WAVE TROUGH ACROSS THE PLAINS WITH A NEARLY 130KT UPPER LEVEL JET DEPARTING THE GREAT LAKES REGION. THIS LEAVES AN ENTRANCE REGION/ENHANCED LIFT ACROSS THE MID MISSISSIPPI RIVER VALLEY. FURTHERMORE...WIND PROFILERS UPSTREAM ALSO SHOW A JET STREAK NEAR 100KTS ACROSS OKLAHOMA WHICH WILL ONLY ENHANCE LIFT. LATEST NCEP NUMERICAL SUITE ALONG WITH RUC ANALYSIS ARE QUITE SIMILAR WITH THE SYNOPTIC ANAFRONTAL CHARACTERISTICS. THIS SHOULD RESULT WITH LITTLE IN THE WAY OF PRECIP SOUTH OF THE CAPITAL REGION TONIGHT AND WILL TAYLOR POPS ACCORDINGLY. TEMPERATURES OVERNIGHT WILL REMAIN NEARLY STEADY OR SLOWLY RISE OVERNIGHT WITH THE INCREASING LOW LEVEL JET AND WARM ADVECTION. SURFACE WAVE WILL TRACK ACROSS NEW YORK STATE ON THANKSGIVING WITH IMPRESSIVE WARM SECTOR ACROSS THE CWA. IF SUNSHINE IS ABLE TO PEAK OUT...COULD SEE TEMPERATURES TAKE A RUN TOWARD 60F IN THE VALLEYS! IN FACT...WE WILL TREND IN THIS DIRECTION FROM THE CAPITAL DISTRICT AND POINTS SOUTHWARD. SHARP COLD FRONT WILL OCCUR DURING THE AFTERNOON HOURS WITH AN ABRUPT WIND SHIFT AND ASSOCIATED TEMPERATURE DROP BY MID-LATE AFTERNOON. BUFKIT PROFILES DO SUGGEST A LITTLE INSTABILITY IN THE MID LEVELS BUT NOT ENOUGH SO TO MENTION THUNDER AT THIS TIME. 850MB TEMPS WILL TUMBLE FROM AROUND +10C DURING THE MORNING TO ALMOST -10C BY EVENING! WILL NEED TO WATCH THOSE MIXING HEIGHTS AND WINDS WITH THE POTENTIAL OF MOHAWK VALLEY CHANNELING. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... UPPER TROUGH EXPECTED TO SWING THROUGH FA IN WAKE OF SURFACE LOW PRESSURE ON THURSDAY NIGHT WITH STRONG VORT AXIS. DESPITE LIMITED MOISTURE IN WAKE OF FRONTAL BOUNDARY EXPECT THAT MOST AREAS WILL SEE AT LEAST SOME SCATTERED SNOW SHOWERS THURSDAY NIGHT INTO FRIDAY MORNING WITH LIMITED LAKE EFFECT CONTINUING THROUGH FRIDAY NIGHT. LOW LEVEL FLOW ON FRIDAY WILL PRIMARILY CONFINE ACTIVITY TO MOHAWK VALLEY ON FRIDAY WITH AXIS LIFTING NORTH INTO WESTERN ADIRONDACKS FRIDAY NIGHT INTO SATURDAY MORNING BEFORE AXIS SHIFTS NORTH OF FA AND WEAKENS AS SHEAR INCREASES AND INSTABILITY DECREASES. HAVE GENERALLY GONE CLOSE TO MAV TEMPS THURSDAY NIGHT THROUGH FRIDAY WITH THURSDAY NIGHT INTO FRIDAY EXPECTED TO BE QUITE WINDY AS STRONG PRESSURE GRADIENT REMAINS IN PLACE ACROSS FA IN WAKE OF EXITING AREA OF LOW PRESSURE AND HIGH PRESSURE BUILDING EAST FROM THE GREAT LAKES. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... MAINLY QUIET WEATHER EXPECTED OVER THE WEEKEND AS A LARGE RIDGE OF HIGH PRESSURE BUILDS OVER FA ON SATURDAY WITH TEMPS REMAINING SLIGHTLY BELOW NORMAL. WEAK TROUGH DROPPING SOUTHEAST FROM CANADA COMBINED WITH LIMITED MOISTURE MAY TURN FLOW BACK INTO WESTERN ADIRONDACKS LATE SATURDAY NIGHT INTO SUNDAY MORNING RESULTING IN SOME MORE LAKE EFFECT SNOW SHOWERS. OTHERWISE EXPECT MAINLY DRY AND COOL CONDITIONS OVER THE WEEKEND WITH TEMPS AVERAGING ABOUT 5 DEGREES BELOW NORMAL ON SATURDAY AND NEAR NORMAL ON SUNDAY. NEXT FORECAST PROBLEM WILL BE LOW PRESSURE LIFTING NORTHEAST FROM OHIO VALLEY AND COLD FRONT DROPPING SOUTHEAST FROM CANADA. AT THIS POINT IT LOOKS LIKE THE FRONT WILL STALL ACROSS OUR FA AND THE LOW PRESSURE SYSTEM WILL LIFT NORTHEAST ALONG IT. THIS SCENARIO WOULD APPEAR TO SPLIT THE FA BETWEEN MIXED PCPN ACROSS NORTHERN PORTIONS OF FA AND MORE LIKELY RAIN ACROSS SOUTHERN PORTIONS ALTHOUGH ANY ATTEMPT TO PINPOINT TRACK THIS FAR OUT IN THE MONDAY INTO TUESDAY TIME FRAME IS DIFFICULT AT BEST. THE GFS AND ECMWF ARE IN FAIRLY GOOD AGREEMENT WITH THIS SCENARIO...THE BIG CONCERN AT THIS POINT BASED ON PARTIAL THICKNESS VALUES IS THE POTENTIAL FOR A WINTRY MIX OF PCPN INCLUDING FREEZING RAIN AND SLEET LATE SUNDAY NIGHT INTO TUESDAY MORNING...WITH THE FREEZING RAIN MAINLY CONFINED TO THE LATE NIGHT AND EARLY MORNING PERIODS. ONCE THIS SYSTEM EXITS A LARGE RIDGE OF HIGH PRESSURE IS THEN EXPECTED TO BUILD INTO THE REGION ON WEDNESDAY WITH NEAR SEASONABLE TEMPERATURES. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... THE STALLED FRONT ACROSS THE NORTHERN PART OF THE FORECAST AREA HAS RESULTED IN IFR OR NEAR IFR FLIGHT CONDITIONS. TO THE NORTH IT IS A COMBINATION OF A LOW STRATUS DECK ALONG WITH AREAS OF RAIN WHILE TO THE SOUTH A LARGE AREA OF FOG WITH VISIBILITY OF 2 MILES OR LESS WAS OVER MOST OF THE HUDSON VALLEY SOUTH OF ALBANY ALONG WITH ADJACENT NORTHWESTERN CONNECTICUT. WINDS AT THE SURFACE WERE LIGHT AND VARIABLE. ALOFT LOW LEVEL WINDS WERE FROM THE SOUTHWEST AROUND 30 TO 35 KNOTS SO WE HAVE INCLUDED LLWS IN THE HUDSON VALLEY TAFS. IFR WITH OCCASIONAL MVFR CONDITIONS MAY BE EXPECTED ACROSS THE REGION THROUGH THIS AFTERNOON AS MOIST AIR HANGS OVER THE REGION WITH ITS STRATUS AND FOG. MODEL FORECASTS INDICATE MOST OF THE RAIN ASSOCIATED WITH THE SURFACE LOW WILL REMAIN TO THE NORTH AND ARE ONLY FORECASTING VCSH AT KPOU FOR THE ENTIRE TAF PERIOD. THE LIKELIHOOD OF RAIN INCREASES AS ONE GOES NORTH. HOWEVER THE RAIN IS NOT LIKELY TO LOWER THE CEILING OR VISIBILITY AND IN FACT MAY EVEN RESULT IN SOME SLIGHT IMPROVEMENT. THE LOW PRESSURE CENTER IS FORECAST TO MOVE THROUGH THE REGION DURING THE AFTERNOON AFTER WHICH WINDS WILL VEER AROUND TO THE WEST AND NORTHWEST. LATE IN THE AFTERNOON WINDS MAY GUST AS HIGH AS 20 KNOTS. FOLLOWING THE FRONTAL PASSAGE FLIGHT CONDITIONS SHOULD IMPROVE TO VFR WITHIN A FEW HOURS EXCEPT NORTH OF THE MOHAWK VALLEY WHERE LOW CLOUDS MAY LINGER FOR A WHILE RESULTING IN MVFR CEILINGS. AS NORTHWESTERLY WINDS USHER IN MUCH COLDER AIR LAKE EFFECT CLOUDS AND SNOW SHOWERS WILL CAUSE CONDITIONS IN THE ADIRONDACKS...THE MOHAWK VALLEY...AND THE NORTHWESTERN CATSKILLS TO DETERIORATE TO MVFR IN THE MOHAWK VALLEY WITH AREAS OF IFR OVER THE HIGHER TERRAIN NORTH AND SOUTH. OUTLOOK... FRIDAY...VFR/MVFR WITH LAKE EFFECT SNOW SHOWERS CATSKILLS NORTH TO ADIRONDACKS. SAT...VFR. SUN...VFR. MON...VFR BECOMING IFR AS RAIN/SNOW/POSSIBLY FZRA MOVES IN. && .HYDROLOGY... MAIN CONCERN AT THIS POINT...WITH THE AREA OF THE HEAVY RAIN BEING MOSTLY NORTH AND WEST OF THE FORECAST AREA...IS THE MOHAWK RIVER IN THE UTICA AREA. WATER IS BEING RELEASED FROM LAKE DELTA TO PROVIDE SOME STORAGE AND THAT HAS RAISED THE RIVER LEVEL ABOUT TWO FEET. FORTUNATELY IT LOOKS LIKE THE RUNOFF FROM THE HEAVIEST RAIN WILL MOSTLY BE IMPOUNDED IN LAKE DELTA...WITH LESS RAIN OVER THE ORISKANY AND SAUQUOIT BASINS WHICH ARE UNCONTROLLED. THE BEAVER AND MOOSE RIVER BASINS ARE ALSO IN THE HEAVY RAIN AREA BUT NO PROBLEMS ARE EXPECTED THERE. SOME RUNOFF MAY ALSO BE EXPECTED OVER THE HEADWATERS OF THE HUDSON...SACANDAGA...AND SCHROON RIVERS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...BGM NEAR TERM...BGM SHORT TERM...11 LONG TERM...11 AVIATION...RCK HYDROLOGY...RCK ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 735 PM EST FRI NOV 23 2007 .SYNOPSIS... 00Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING AN INCREASINGLY AMPLIFIED PATTERN ACROSS THE CONUS...ESPECIALLY TO THE WEST OF THE MISSISSIPPI RIVER. SHARP RIDGING ALONG AND JUST OFF THE PACIFIC COAST DIVES UPSTREAM INTO A POSITIVELY TILTED TROUGH OVER THE INTERMOUNTAIN WEST AND NORTHERN PLAINS. VERY SHARP PIECE OF SHORTWAVE ENERGY IS SEEN ROTATING AROUND THE BASE OF THIS TROUGH FROM SOUTHERN CALIFORNIA TO THE FOUR CORNERS REGION. FLOW THEN BECOMES BRIEFLY ZONAL FURTHER DOWNSTREAM FROM THE SOUTHEASTERN STATES TO THE TENNESSEE AND OHIO VALLEYS BEFORE DIVING INTO YET ANOTHER SHORTWAVE OVER THE NORTHEASTERN STATES. AT THE SURFACE OUR FORECAST AREA RESIDES ON THE SOUTHERN PERIPHERY OF HIGH PRESSURE CENTERED OVER THE OHIO VALLEY. THE FLOW AROUND THIS HIGH CONTINUES TO DELIVER A SUPPLY OF DRY AND COOL AIR FROM THE NORTH AND NORTHEAST. && .DISCUSSION... MOSTLY CLEAR SKIES THIS EVENING WILL BEGIN TO FILL WITH MORE AND MORE HIGH AND MID LEVEL CLOUDS OVER THE NEXT 12 TO 18 HOURS. LOW TEMPS ARE STILL EXPECTED TO REACH THE UPPER 30S TO LOWER 40S OVER MANY INLAND LOCATIONS OVERNIGHT. SOME CONCERN...THE INCREASING HIGH CLOUDS LATE WILL SLOW THE TEMPERATURE FALL...HOWEVER THINK THE THICKER CLOUDS WILL HOLD OFF UNTIL SATURDAY MORNING. CERTAINLY WILL SEE AN INCREASE IN CLOUDS DURING THE DAY ON SATURDAY ALTHOUGH ANY RAIN CHANCES SHOULD HOLD OFF UNTIL THE EVENING HOURS OR LATER. GUIDANCES HAS CONTINUED THE TREND OF BRINGING THE BEST LIFT AND MOISTURE FURTHER WEST WITH TIME. WHAT DID LOOK LIKE A PRETTY GOOD CHANCE OF WIDESPREAD RAINFALL OVER THE AREA 24 HOURS AGO IS NOW IN JEOPARDY. THE BEST ISENTROPIC LIFT ALONG A WARM EXTENDING INTO OUR COASTAL WATERS FROM DEVELOPING LOW PRESSURE IN THE WESTERN GOMEX IS NOW EXPECTED TO STAY OVER OUR FAR WESTERN ZONES AND WESTWARD. THE REMAINDER OF OUR FORECAST AREA NOW LOOKS TO RECEIVE MUCH MORE SPOTTY SHOWER ACTIVITY WITH QPF AMOUNTS SIGNIFICANTLY LESS THAN EARLIER THOUGHT THROUGH SUNDAY MORNING. AS A SURFACE LOW EJECTS OUT OF THE WESTERN GULF OF MEXICO TOWARD THE LOWER MISSISSIPPI VALLEY SUNDAY AFTERNOON AND NIGHT...IT WILL DRAG THE WARM FRONT TO OUR NORTH AND BRING A PERIOD OF MAINLY RAIN FREE AND WARM CONDITIONS. THE SURFACE LOW WILL THEN RAPIDLY MOVE NORTHEAST INTO THE OHIO VALLEY DRAGGING A COLD FRONT THROUGH THE SOUTHEAST MONDAY AND MONDAY NIGHT. EXPECTING ANOTHER SHOT AT A SHOWER OR THUNDERSTORM WITH THIS FRONTAL PASSAGE. && .MARINE... SOLID CAUTIONARY CONDITIONS CONTINUE ACROSS THE COASTAL LEGS THIS EVENING WITH NORTHEASTERLY FLOW BETWEEN 15 AND 20 KNOTS. AS THE HIGH TO OUR NORTH CONTINUES TO MOVE EASTWARD WILL EXPECT TO SEE WINDS COME AROUND TO A MORE EASTERLY DIRECTION BY SUNRISE TOMORROW BUT REMAIN AT OR CLOSE TO CAUTIONARY LEVELS. FLOW CONTINUES TO VEER AROUND TO THE SOUTHEAST BY SATURDAY EVENING WITH RAIN/THUNDERSTORM CHANCES RETURNING. && .AVIATION... THE OVERNIGHT HOURS WILL FEATURE VFR CONDITIONS AT ALL LOCAL AREA TERMINALS, WITH JUST SOME CIRRUS CLOUDS EDGING NWD AND EWD ACROSS THE AREA. MID CLOUDS MOVE IN AHEAD OF AN ADVANCING WARM FRONT DURING THE MORNING SAT. LOWER CLOUDS WILL ARRIVE AROUND MIDDAY WITH CEILINGS IN THE MVFR RANGE BY AFTERNOON FOR TLH, PFN, AND VLD, AND 3-4 KFT AT DHN AND ABY. THERE IS A SLIGHT CHANCE FOR RAIN AT THE TERMINALS DURING THE AFTERNOON, BUT MOST OF THAT SHOULD HOLD OFF UNTIL THE OVERNIGHT HOURS SAT NIGHT. && .FIRE WEATHER... THE RH WILL REMAIN ABOVE THE CRITICAL 35 PERCENT LEVEL SATURDAY AFTERNOON AS LOW LAYER MOISTURE INCREASES FROM THE SOUTH. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 38 66 52 74 59 / 0 20 60 40 30 PANAMA CITY 43 65 55 74 61 / 0 20 80 50 40 DOTHAN 36 59 49 68 57 / 0 20 80 60 50 ALBANY 36 60 46 68 57 / 0 20 60 60 40 VALDOSTA 39 64 49 73 58 / 0 20 40 40 30 CROSS CITY 41 71 53 77 59 / 0 20 30 20 30 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GMZ750...NONE. GMZ755...NONE. GMZ770...NONE. GMZ775...NONE. && $$ AVIATION...WOOL FIRE WX...WATSON PUBLIC/MARINE...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 943 AM EST FRI NOV 23 2007 .SYNOPSIS... THE 12 UTC REGIONAL SURFACE ANALYSIS SHOWED A COLD FRONT ACROSS CENTRAL FL...EXTENDING SOUTHWESTWARD INTO THE GULF FOR SEVERAL HUNDRED MILES. THE 12 UTC KTAE SOUNDING SHOWED AN UNUSUALLY SHALLOW CP AIRMASS...WITH THE COLD AIR ONLY EXTENDING UP TO ABOUT THE 950 MB LEVEL (2K FT). EVEN WITH A LOT OF SUN WE WILL NOT BREAK THE STRONG CAP ABOVE THIS COLD LAYER...SO AFTERNOON HIGHS WILL BE COOL AND A LITTLE BELOW AVERAGE FOR THIS TIME OF YEAR (UPPER 50S TO MID 60S). VAPOR IMAGERY AND UPPER AIR PROFILERS SHOW A SHORT WAVE TROUGH PROPAGATING EASTWARD OVER THE SOUTHEAST...AND THERE ARE SOME MID TO UPPER LEVEL CLOUDS (AND EVEN A FEW SPRINKLES/FLURRIES) ASSOCIATED WITH THIS FEATURE TO OUR NORTH AND WEST. ALL OF THE NUMERICAL GUIDANCE FORECASTS THESE CLOUDS TO DISSIPATE BY AFTERNOON. THE LATEST BLEND OF THE GFS MOS...WRF...AND RUC YIELD FAIRLY LOW DEWPOINTS THIS AFTERNOON...BUT WE THINK TEMPERATURES WILL BE A LITTLE COOL TO REACH RED FLAG CONDITIONS. THERE COULD BE A FEW POCKETS OF 1 TO 2 HOURS NEAR 35 PERCENT. THE WINDS HAVE BEEN SLOW TO INCREASE OVER OUR COASTAL WATERS THIS MORNING...DESPITE A PRETTY TIGHT PRESSURE GRADIENT. WE DROPPED THE SMALL CRAFT ADVISORY FOR OUR NEAR SHORE WATERS BUT KEPT IT UP FOR OUR OUTER WATERS FOR MARGINAL ADVISORY CONDITIONS. && .AVIATION... MVFR CLOUDS ASSOCIATED WITH THE COLD FRONT CONTINUE TO PUSH SOUTHEAST AND WILL EXIT THE EXTREME SOUTHEAST FLORIDA BIG BEND BY 15-16Z. ELSEWHERE...PATCHES OF MIDDLE CLOUDS ACROSS SOUTHERN ALABAMA WITH A FEW OCCASIONAL SPRINKLES WILL CONTINUE EASTWARD INTO CENTRAL AND SOUTH CENTRAL GEORGIA THIS AFTERNOON AND WEAKENING SOMEWHAT THROUGH THE REST OF THE DAY. OTHERWISE...THE REMAINDER OF TODAY AND TONIGHT WILL BE MOSTLY CLEAR. ON SATURDAY...MID AND HIGH CLOUDS WILL BEGIN TO APPROACH FROM THE WEST WITH THE POSSIBILITY OF SHOWERS BEGINNING LATE IN THE AFTERNOON. && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GMZ750...NONE. GMZ755...NONE. GMZ770...SMALL CRAFT ADVISORY. GMZ775...SMALL CRAFT ADVISORY. && $$ AVIATION...WATSON REST OF DISCUSSION...FOURNIER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 715 PM EST THU NOV 22 2007 .SYNOPSIS... 00Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING AN UNUSUALLY DOMINANT LONG WAVE TROUGH COVERING ALMOST THE ENTIRE CONUS. EMBEDDED WITHIN THE LARGER TROUGH WE WEE SEVERAL DISTINCT PIECES OF SHORTWAVE ENERGY...INCLUDING ONE SHORTWAVE PUSHING EAST OUT OF THE UPPER MISSISSIPPI VALLEY AND A SERIES OF SHORTWAVES DIVING SOUTH THROUGH THE INTER-MOUNTAIN WEST ALONG THE WESTERN PERIPHERY OF THE TROUGH. AT THE SURFACE...COLD FRONT HAS BEEN MAKING STEADY PROGRESS EASTWARD THROUGH THE AFTERNOON AND IS NOW RUNNING FROM SOUTH-CENTRAL GA INTO THE WESTERN BIG BEND AND OUT INTO THE WESTERN COASTAL WATERS. && .DISCUSSION... A THIN BROKEN LINE OF SHOWERS/SPRINKLES IS SEEN ON REGIONAL RADARS RIGHT ALONG THE FRONTAL BOUNDARY AND A BRIEF SHOWER OR SPRINKLE CAN NOT BE RULED OUT THIS EVENING ACROSS OUR EASTERN ZONES UNTIL THE FRONT PASSES. A WIND SHIFT TO THE NORTHWEST WHICH HAS OCCURRED ACROSS THE NORTHWEST HALF OF THE AREA CAN BE EXPECTED WITH THE FRONTAL PASSAGE. WITH THE WIND SHIFT DEWPOINTS WILL DROP WITHIN A FEW HOURS FROM THE LOWER 60S THROUGH THE 50S AND INTO THE UPPER 40S. TEMPERATURES WILL ALSO FALL THROUGH THE 50S AND EVENTUALLY 40S LATER TONIGHT. AS WAS MENTIONED IN THE PREVIOUS DISCUSSION...THE TIGHT GRADIENT BEHIND THE FRONT COMBINED WITH PLENTY OF LOW/MID LEVEL CLOUDS WILL HELP KEEP TEMPS FROM FALLING ALL THAT RAPIDLY OVERNIGHT. A COOLER BUT DRIER DAY FOR FRIDAY AS NORTH-NORTHEAST WINDS CONTINUE TO DELIVER A CONTINENTAL POLAR AIRMASS TO THE SOUTHEASTERN STATES. HIGH TEMPS WILL END UP BELOW CLIMO WITH LOWER AND MIDDLE 60S ABOUT THE MOST WE CAN EXPECT. THEREAFTER THE BIG STORY WILL BE THE DEVELOPMENT OF LOW PRESSURE IN THE WESTERN GULF OF MEXICO SATURDAY AND SATURDAY NIGHT. A WARM FRONT ASSOCIATED WITH THE DEVELOPING LOW WILL EXTEND EAST INTO THE NORTHEAST GULF BY LATE SATURDAY. AT THIS TIME GUIDANCE IS IN FAIRLY GOOD AGREEMENT IN HOLDING OFF THE BEST RAIN CHANCES UNTIL SATURDAY EVENING OR NIGHT. BY SATURDAY NIGHT THOUGH...GFS/NAM/ECMWF ALL SHOWING STRONG DEEP LAYER ISENTROPIC LIFT ALONG THE 300-310K SURFACES WHICH WILL LIKELY RESULT IN A WIDESPREAD AREA OF RAIN SPREADING INLAND FROM THE COASTAL WATERS. ALTHOUGH IT IS STILL EARLY FOR DETAILS...THE POTENTIAL IS CERTAINLY THERE FOR WIDESPREAD BENEFICIAL RAIN. AS IS THE CASE WHEN ANY WELL DEFINED WARM FRONT APPROACHES THE COAST...WE WILL HAVE TO CONSIDER THE POSSIBILITY OF A FEW STRONGER ROTATING STORMS DEVELOPING OVER THE COASTAL WATERS AND MOVING TOWARD THE COAST. THE 0-6KM BULK SHEAR AND THE LOW LEVEL SHEAR AROUND THE FRONT ARE CERTAINLY SUBSTANTIAL ENOUGH... HOWEVER THE INSTABILITY (AT LEAST FOR NOW) LOOKS TO BE LACKING EVEN AT THE COAST. LATEST SREF ENSEMBLE MEMBERS ARE IN VERY GOOD AGREEMENT IN KEEPING THE 500 J/KG CAPE CONTOUR SOUTH OF THE COAST SATURDAY NIGHT/SUNDAY MORNING. IN FACT THE LATEST PROBABILITY OF THE 500 J/KG CAPE CONTOUR EVEN REACHING THE IMMEDIATE SHORELINE IS ONLY AROUND 10%. HOWEVER...DO EXPECT A FEW STRONGER ROTATING STORMS TO DEVELOP ACROSS OUR OFFSHORE MARINE LEGS SATURDAY NIGHT WHERE THE CHANCES FOR BETTER INSTABILITY ALONG AND JUST NORTH OF THE WARM FRONT WILL BE FOUND. WILL CONTINUE TO MONITOR THE SITUATION AS THE LOW ACTUALLY DEVELOPS TO MAKE SURE THE BEST INSTABILITY DOES NOT BEGIN TO EDGE FURTHER NORTH. && .MARINE... COLD FRONT CONTINUES TO CROSS THE FORECAST WATERS THIS EVENING AND WILL BE PASSING SOUTH AND EAST OF THE AREA BY AROUND MIDNIGHT. WINDS BEHIND THE FRONT WILL COME AROUND TO THE NORTHWEST AND THE NORTH WITH SHOWER/STORM CHANCES ENDING. LATEST GUIDANCE HAS ACTUALLY COME DOWN JUST A BIT ON THE WIND SPEEDS TONIGHT AND EARLY FRIDAY BEHIND THE FRONT. STILL LOOKS LIKE A MARGINAL SMALL CRAFT ADVISORY EVENT SO WILL NOT DROP THE ADVISORY AT THIS TIME. WINDS COME AROUND TO THE NORTHEAST DURING FRIDAY WITH CAUTION TO ADVISORY LEVEL CONDITIONS CONTINUING INTO THE WEEKEND. && .AVIATION... SHOWERS ALONG AND AHEAD OF THE COLD FRONT WILL SWEEP FROM WEST TO EAST AND CONTINUE TO WEAKEN ACROSS THE ERN BIG BEND AND SCNTRL GA FOR THE REMAINDER OF THE EVENING. OTHERWISE...CIGS WILL ALTERNATE FROM MVFR/IFR AT MOST TAF SITES UNTIL MUCH DRIER AIR FILTERS IN BEGINNING AROUND MIDNIGHT ACROSS WRN TERMINALS AND THEN DURING THE PREDAWN HOURS ACROSS ERN TERMINALS. BY SUNRISE VFR CONDS ACROSS ENTIRE TRI-STATE AREA. && .FIRE WEATHER... WE MAY SEE ONE TO THREE HOUR DURATIONS OF LOW RH ACROSS PORTIONS OF NORTH FLORIDA FRIDAY AFTERNOON. OTHERWISE...NO CONCERNS FOR THE NEXT SEVERAL DAYS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 47 62 41 62 54 / 0 0 0 50 80 PANAMA CITY 45 64 46 66 58 / 0 0 0 60 80 DOTHAN 42 61 39 58 52 / 0 0 0 40 80 ALBANY 43 63 42 58 51 / 0 0 0 30 80 VALDOSTA 49 63 43 62 54 / 15 0 0 30 80 CROSS CITY 50 67 46 71 59 / 20 0 0 40 70 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GMZ...SMALL CRAFT ADVISORY. && $$ AVIATION...BLOCK FIRE WX...BARRY PUBLIC/MARINE...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 303 AM EST THU NOV 22 2007 .SYNOPSIS... A COLD FRONT WILL PUSH THROUGH THE REGION THIS AFTERNOON...BRINGING SOME LIGHT SHOWERS WITH IT. HIGH PRESSURE WILL BUILD IN TONIGHT INTO THE WEEKEND. AN AREA OF LOW PRESSURE WILL DEVELOP IN THE GULF OF MEXICO AND MOVE TOWARDS OUR REGION BY LATE SATURDAY AND SUNDAY...BRINGING INCREASED CHANCES FOR PRECIPITATION. ANOTHER COLD FRONT WILL MOVE THROUGH MONDAY. DRY WEATHER WILL RETURN TO THE REGION LATER ON TUESDAY. && .NEAR TERM /THROUGH TODAY/... LATEST SURFACE ANALYSIS INDICATES A LOW PRESSURE SYSTEM LOCATED OVER SOUTHERN OHIO WITH A COLD FRONT EXTENDING SOUTHWARD THROUGH TENNESSEE INTO NORTHWEST ALABAMA AT THIS TIME. REGIONAL RADAR SHOWS SCATTERED SHOWERS IN THE WARM ADVECTION AHEAD OF THE COLD FRONT...WITH A MORE SUBSTANTIAL BAND OF PRECIPITATION ALONG THE FRONT. THE FRONT IS EXPECTED TO PUSH THROUGH THE MIDLANDS DURING THE AFTERNOON HOURS. CHANCES OF RAIN WILL INCREASE AS THE FRONT APPROACHES AND HAVE BUMPED POPS UP TO LIKELY AS IT APPEARS MEASURABLE PRECIPITATION IS LIKELY...BUT AMOUNTS WILL BE QUITE LIGHT...MAYBE UP TO A TENTH OF AN INCH. TEMPERATURES ARE QUITE MILD CURRENTLY AS SOUTHERLY WINDS AROUND 10 MPH ARE KEEPING THE ATMOSPHERE WELL MIXED. EXPECT TO SEE HIGHS IN THE LOW TO MID 70S BEFORE THE FRONT PUSHES THROUGH...AND WINDS SHOULD INCREASE TODAY WITH SPEEDS AROUND 15 TO 20 MPH. A LAKE WIND ADVISORY IS ALREADY POSTED AND THAT LOOKS GOOD. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... PRECIPITATION MAY LINGER EARLY THIS EVENING ALONG AND EAST OF I-20 BUT SHOULD BE GONE BY 03Z. HIGH PRESSURE WILL BUILD IN OVERNIGHT IN THE WAKE OF THE FRONT...USHERING IN COOLER AND DRIER AIR. TEMPERATURES WILL BE QUITE DIFFERENT FOR FRIDAY THROUGH THE WEEKEND AS A COLD AIRMASS SETTLES OVER THE REGION. TEMPERATURES WILL BE WELL BELOW NORMAL DURING THE PERIOD. ANOTHER VIGOROUS SHORTWAVE WILL DIVE INTO THE FOUR CORNERS REGION ON FRIDAY...BUT MODELS ARE STRUGGLING TO HANDLE THE TIMING AND STRENGTH OF THE SYSTEM WHICH IS RESULTING IN VARIOUS SOLUTIONS AND THEREFORE SENSIBLE WEATHER DOWNSTREAM OVER THE SOUTHEASTERN CONUS. IT DOES APPEAR THAT WARM ADVECTION AND SOME OVERRUNNING WILL TAKE PLACE SOMETIME BETWEEN LATE SATURDAY AND DURING THE DAY SUNDAY...BUT THAT IS UNCERTAIN AT THIS TIME. HAVE NOT CHANGED THE POPS MUCH DURING THIS PERIOD TO CONTINUE WITH SOME PERSISTENCE UNTIL THE MODELS CONVERGE ON A SOLUTION. STRONG HIGH PRESSURE SETTING UP OVER THE NORTHEAST AND MID ATLANTIC REGION IS SHOWING SIGNS THAT WE MIGHT EXPERIENCE SOME WEDGING BY SUNDAY...AND HAVE LOWERED MAXIMUM TEMPERATURES A BIT TO ACCOUNT FOR THIS. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... SLIGHT BREAK BETWEEN SYSTEMS SUNDAY NIGHT AS ON SYSTEM EXITS UP THE EAST COAST...AND ANOTHER DEVELOPS IN THE GULF OF MEXICO. WILL HOLD ON TO CHANCE POPS FOR NOW DUE TO UNCERTAINTY IN TIMING OF EXITING SYSTEM. NEXT SYSTEM DEVELOPS IN THE NORTHERN GULF AND MOVES TOWARDS THE STATE MONDAY. BEST CHANCE FOR RAINFALL WOULD APPEAR TO BE LATE MONDAY AFTERNOON AND NIGHT. COLD FRONT MOVES THROUGH TUESDAY MORNING...WITH DRYING EXPECTED IN ITS WAKE. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... SOUTHWEST WIND FLOW AROUND 10 KT AT THE SURFACE WITH CONTINUE OVERNIGHT AHEAD OF AN APPROACHING COLD FRONT. THIS WILL SPREAD MOISTURE IN THE FORM OF CLOUDS OVER THE AREA 06Z-13Z EARLY THIS MORNING. VFR CONDITIONS ARE EXPECTED AS CLOUD BASES ARE EXPECTED TO BE 4-6 KFT WITH VSBYS 7 MILES. MAIN PROBLEM OVERNIGHT WILL BE INCREASING LOW LEVEL WINDS 1-2 KFT. BOTH NAM AND RUC FORECAST RAOBS ARE SHOWING WINDS BECOMING SOUTHWEST AT 35 KT NEAR THE 1.5 KFT LEVEL BY 03Z AND CONTINUING THROUGH 13Z WHEN SURFACE WINDS INCREASE TO 15-20 KT. SO WILL CONTINUE THE MENTION OF LOW LEVEL WIND SHEAR SURFACE-1.5 KT 03Z-12Z. AFTER 13Z...MAINLY VFR CONDITIONS WITH CIGS NEAR 4 KFT AND VSBYS 7 MILES. A COLD FRONT SHOULD MOVE THROUGH THE AREA 18Z-24Z TIME FRAME. BRIEF MVFR CONDITIONS POSSIBLE IN SHOWERS 18Z-24Z BUT GENERALLY VFR. COLD FRONT AND SHOWERS MOVE EAST AS HIGH PRESSURE BUILDS OVER AREA 00Z-06Z WITH VFR CONDITIONS...SCATTERED CLOUDS 4-5 KFT AND VSBYS 7 MILES OR BETTER. VFR CONDITIONS BY 06Z FRIDAY THROUGH MONDAY WITH NO SIGNIFICANT AVIATION IMPACTS EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...LAKE WIND ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR SCZ015- 016-018-020>022-025>031-035>038-041. GA...LAKE WIND ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR GAZ040- 063>065-077. && $$ SYNOPSIS...HC NEAR TERM...HC SHORT TERM...HC LONG TERM...HC AVIATION...CL ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 1223 AM EST THU NOV 22 2007 .SYNOPSIS... HIGH PRESSURE OFF OF THE SOUTHEAST COAST WILL SLOWLY GIVE WAY TO AN APPROACHING COLD FRONT. COLD FRONT WILL CROSS THE AREA DURING THE AFTERNOON ON THURSDAY. THERE WILL BE A CHANCE OF SHOWERS AHEAD OF THE FRONT LATE TONIGHT AND THANKSGIVING DAY. EXPECT COOLER CONDITIONS BEHIND THE FRONT FOR FRIDAY. AN AREA OF LOW PRESSURE WILL DEVELOP IN THE GULF OF MEXICO AND MOVE TOWARDS OUR REGION BY LATE SATURDAY AND SUNDAY. ANOTHER COLD FRONT WILL MOVE THROUGH MONDAY. DRY WEATHER WILL RETURN TO THE REGION LATER ON TUESDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... REGIONAL COMPOSITE RADAR SHOWING AREA OF MAINLY LIGHT SHOWERS ACROSS PORTIONS OF NORTHERN GA EXTENDING INTO SE AL. FEW SHOWERS ALSO NOTED OVER PARTS OF THE SC UPSTATE AND NORTHERN MIDLANDS. FEW CHANGES TO ZONES OTHER THAN WORDING CHANGES TO PRECIPITATION TRENDS OVERNIGHT. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... THE COLD FRONT SHOULD MOVE THROUGH THE MIDLANDS SOMETIME DURING THE AFTERNOON HOURS ON THURSDAY (18Z-21Z)...FOLLOWED BY COLD ADVOCATION ON NORTHWESTERLY FLOW OVERNIGHT AND THROUGH THE DAY FRIDAY. WITH MOISTURE AND INSTABILITY INCREASING AHEAD OF THE FRONT EXPECT A GOOD CHANCE OF SHOWERS ON THURSDAY. RAINFALL AMOUNTS WILL GENERALLY BE AROUND .25 INCH OR LESS. RAINFALL WILL END ACROSS THE REGION EARLY THURSDAY NIGHT WITH CLEARING SKIES FOLLOWING THE FRONT ACROSS THE AREA. LOWS BY FRIDAY MORNING WILL BE COOLER DROPPING INTO THE 40S. TEMPERATURES WILL STILL BE MILD THURSDAY WITH SOUTHWESTERLY FLOW AND A WELL MIXED ATMOSPHERE AS WINDS WILL BE FAIRLY STRONG. HIGHS ON FRIDAY WILL BE SUBSTANTIALLY COOLER AND BELOW NORMAL WITH HIGHS IN THE UPPER 50S TO AROUND 60...SOME 15 TO 20 DEGREES COOLER THAN THURSDAY. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... THE LONG WAVE PATTERN CONSISTING OF A STRONG BERMUDA HIGH ANCHORED JUST OFF THE COAST OF THE SOUTHEAST UNITED STATES AND A TROFF IN THE WEST IS TRYING TO MAKE A CHANGE AS A VIGOROUS SHORT WAVE TROFF CURRENTLY OFF THE CENTRAL CALIFORNIA COAST TRIES TO SWING EAST ACROSS THE GULF STATES. THIS CHANGE WILL BRING MORE MOISTURE OFF THE GULF OF MEXICO INTO THE SOUTHEASTERN UNITED STATES BRINGING WITH IT AN INCREASE IN THE CHANCE FOR SIGNIFICANT RAIN. HOWEVER MODEL GUIDANCE IS CONFLICTED IN HANDLING THE SYSTEM. THE CANADIAN GEM MODEL DEVELOPS IT OVER EASTERN TEXAS MONDAY MORNING AND MOVES IT TO NORTHERN PENNSYLVANIA BY TUESDAY MORNING WITH THE ECMWF DEVELOPING IT OVER SOUTHERN LOUISIANA SUNDAY NIGHT AND MOVING IT TO WESTERN NEW YORK BY MONDAY NIGHT AND THE GFS DEVELOPING IT NEAR NEW ORLEANS AND MOVING IT TO CENTRAL OHIO BY MONDAY NIGHT. THE GFS DEVELOPS A STRONGER LOW THEN THEN THE GEM OR THE ECMWF WHICH WOULD GIVE THE SOUTHEASTERN UNITED STATES THE BEST CHANCE OF RAINFALL. THE FORECAST WAS BASED HPC GUIDANCE WHICH SEEMS TO LEAN TOWARD THE GFS SOLUTION AND IS CLOSE TO THE CURRENT FORECAST. WITH SO MUCH UNCERTAINTY...FEW CHANGES WERE MADE TO THE CURRENT FORECAST PACKAGE. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... SOUTHWEST WIND FLOW AROUND 10 KT AT THE SURFACE WITH CONTINUE OVERNIGHT AHEAD OF AN APPROACHING COLD FRONT. THIS WILL SPREAD MOISTURE IN THE FORM OF CLOUDS OVER THE AREA 06Z-13Z EARLY THIS MORNING. VFR CONDITIONS ARE EXPECTED AS CLOUD BASES ARE EXPECTED TO BE 4-6 KFT WITH VSBYS 7 MILES. MAIN PROBLEM OVERNIGHT WILL BE INCREASING LOW LEVEL WINDS 1-2 KFT. BOTH NAM AND RUC FORECAST RAOBS ARE SHOWING WINDS BECOMING SOUTHWEST AT 35 KT NEAR THE 1.5 KFT LEVEL BY 03Z AND CONTINUING THROUGH 13Z WHEN SURFACE WINDS INCREASE TO 15-20 KT. SO WILL CONTINUE THE MENTION OF LOW LEVEL WIND SHEAR SURFACE-1.5 KT 03Z-12Z. AFTER 13Z...MAINLY VFR CONDITIONS WITH CIGS NEAR 4 KFT AND VSBYS 7 MILES. A COLD FRONT SHOULD MOVE THROUGH THE AREA 18Z-24Z TIME FRAME. BRIEF MVFR CONDITIONS POSSIBLE IN SHOWERS 18Z-24Z BUT GENERALLY VFR. COLD FRONT AND SHOWERS MOVE EAST AS HIGH PRESSURE BUILDS OVER AREA 00Z-06Z WITH VFR CONDITIONS...SCATTERED CLOUDS 4-5 KFT AND VSBYS 7 MILES OR BETTER. VFR CONDITIONS BY 06Z FRIDAY THROUGH MONDAY WITH NO SIGNIFICANT AVIATION IMPACTS EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...LAKE WIND ADVISORY FROM 5 AM EARLY THIS MORNING TO 6 PM EST THIS AFTERNOON FOR SCZ015-016-018-020>022-025>031-035>038- 041. GA...LAKE WIND ADVISORY FROM 5 AM EARLY THIS MORNING TO 6 PM EST THIS AFTERNOON FOR GAZ040-063>065-077. && $$ ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 334 AM CST FRI NOV 23 2007 .DISCUSSION... ISSUED 302 AM CST FRI NOV 23 2007 SFC HIGH PRESSURE OVER THE CENTER OF THE CONUS...WITH THE MIDWEST STILL IN NRLY FLOW BEHIND EXITING SYSTEM. SOME LLVL CLOUDS KEEPING THE TEMPS IN THE MID TO UPPER 20S FOR MUCH OF THE CWA...THOUGH AREAS THAT HAVE BEEN ABLE TO CLEAR OUT ARE DROPPING TO THE LOWER 20S THIS MORNING. LLVL CLOUDS FINALLY BEGINNING TO BREAK UP ON SATELLITE IMAGERY. MODELS RELATIVELY IN AGREEMENT THROUGH THE SHORT AND MID TERM WITH THE ONLY DIFFERENCE SHOWING UP EARLY IN THE WORK WEEK AS THE NEXT PRECIP CHANCE MOVES IN FROM THE SW. MAIN DIFFERENCE AT THIS POINT IS WITH THE TRACK. ALL MODELS HAVE SPED UP THE SPEED OF THE SYSTEM AS BEYOND DAY 4 AS IT EXITS THE REGION...BUT THE ARRIVAL TIME HAS MAINTAINED CONTINUITY. AT ANY RATE...HAVE GONE WITH A BLEND...WEIGHTED ONLY SLIGHTLY TO THE ECMWF. SHORT TERM...TODAY AND TOMORROW... BECOMING MORE SUNNY AS THE DAY PROGRESSES AND THE LOW CLOUDS CONTINUE TO BREAK UP. OVERNIGHT TEMPS ARE A BIT OF AN ISSUE FOR THE FORECAST AS CLOUDS WILL BE COMING BACK INTO THE REGION WITH SOUTHERLY FLOW AS THE RIDGE MOVES EAST AFTER MIDNIGHT...EFFECTIVELY ENDING THE MOST AGGRESSIVE RADIATIONAL COOLING CLOSER TO DAWN. HAVE GONE VERY CLOSE TO MOS...BUT SLIGHTLY UNDER FOR UNCERTAINTY IN THE CLOUD COVERAGE. TOMORROW...SOUTHERLY WINDS EDGE UP THE TEMPERATURES SLIGHTLY FROM THE DAY BEFORE...BUT CLOUDS KEEP THE MORNING RATHER COOL BEFORE NOON. LONG TERM...SUNDAY THROUGH TUESDAY... ANOTHER TROF DIGS OUT OVER THE DESERT SW AND MOVES INTO THE SRN PLAINS ON SUNDAY. COLD AND DRY CONTINUES THROUGH THE END OF THE WEEKEND UNTIL THE WAVE PUSHES OUT OF THE SRN PLAINS...MAKING ITS WAY TO THE MIDWEST LATE SUNDAY/EARLY MONDAY. PRECIP RETURNING TO THE FORECAST FOR SUNDAY NIGHT AND MONDAY...WITH THE SFC LOW SLIDING BY LATE MONDAY AND INTO THE OVERNIGHT HOURS. THE MODELS ALSO HAVE A DIFFERENCE IN TRACK...WITH THE CAN/GLOB NOW THE SRN OUTLIER (PREVIOUSLY MORE MIDDLE)...AND THE ECMWF MAINTAINING ITS FURTHER TO THE NORTH TRACK...THOUGH SLIGHTLY SOUTH OF LAST 00Z RUN. THE GFS AND THE NAM ARE SURPRISINGLY SIMILAR TO ONE ANOTHER...AND NOT FAR OFF FROM THE ECMWF. MODELS TRENDING TOGETHER GIVES A BIT MORE CONFIDENCE WITH THIS FORECAST THAN THE LAST...AND BEST CHANCES FOR PRECIP SUNDAY NIGHT AND ESP MONDAY. TUESDAY SEES A SLOW RETURN TO DRIER CONDITIONS. HJS && .AVIATION... ISSUED 1144 PM CST THU NOV 22 2007...FOR THE 06Z TAFS BREAKS IN THE CLOUD COVER ARE PROGRESSING SOUTH INTO OUR EASTERN CWA...VERY CLOSE TO THE RUC FORECAST LOW LEVEL RH. A BAND OF 035 TO 040 CLOUDS WILL LIKELY REMAIN ACROSS THE WESTERN HALF OF THE CWA THROUGH MORNING. WILL TRY TO TEMPO AROUND THE CLEARING SPOTS...ALTHOUGH A FEW MAY CREEP TOWARD PIA AND SPI. DEC...BMI...AND CMI WILL HAVE THE BEST CHANCE FOR EXTENDED PERIODS OF CLEARING THE REST OF THE NIGHT...AND I TRIED TO PORTRAY THAT IN THE TIMING OF CLEARING CLOUDS. CU RULE PLOTS SHOW CLEAR SKIES OR SCATTERED CLOUDS ACROSS OUR CWA TOMORROW. WILL NOT PUT ANY TEMPO BKN DECKS AS A RESULT. NO MAJOR ISSUES FOR LOW VIS OR CIGS FOR THIS TAF ISSUANCE. WINDS WILL REMAIN LIGHT AS WELL. SHIMON && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1145 PM CST THU NOV 22 2007 .DISCUSSION... ISSUED 848 PM CST THU NOV 22 2007 LOW CLOUDS AND FLURRIES WILL LIKELY LINGER THE REST OF THE NIGHT...BASED ON SATELLITE AND RADAR INDICATIONS. A STRONG H5 VORT MAX WILL AFFECT OUR CWA...AS THE AXIS OF THE H5 TROUGH PASSES ACROSS OUR CWA BETWEEN MIDNIGHT AND 6 AM. THE DPVA WILL NOT BE AS EFFECTIVE AT GENERATING LIFT AS IT COULD BE...BECAUSE IT IS MORE CHANNELED THAN PRE TROUGH DPVA. THEREFORE...I ADJUSTED THE WEATHER GRIDS TO INCLUDE FLURRIES THE REST OF THE NIGHT. TEMPS ARE ON TRACK...AS CLOUDY TO MOSTLY CLOUDY SKIES ARE EXPECTED THE REST OF THE NIGHT. A FEW HOLES IN THE CLOUDS WILL DEVELOP IN OUR NE CWA...AS INDICATED BY SATELLITE IMAGES...AND THE RUC RH FORECAST. THIS WILL ALLOW TEMPS TO DIP INTO THE LOWER 20S IN A FEW LOCATIONS ACROSS THE NORTHERN CWA. THIS WAS ALREADY HANDLED WELL IN THE LOW TEMP GRID. THE REST OF THE FORECAST WAS DOING WELL. THE UPDATED GRIDS AND ZONES ARE ALREADY AVAILABLE. SHIMON && .AVIATION... ISSUED 1144 PM CST THU NOV 22 2007...FOR THE 06Z TAFS BREAKS IN THE CLOUD COVER ARE PROGRESSING SOUTH INTO OUR EASTERN CWA...VERY CLOSE TO THE RUC FORECAST LOW LEVEL RH. A BAND OF 035 TO 040 CLOUDS WILL LIKELY REMAIN ACROSS THE WESTERN HALF OF THE CWA THROUGH MORNING. WILL TRY TO TEMPO AROUND THE CLEARING SPOTS...ALTHOUGH A FEW MAY CREEP TOWARD PIA AND SPI. DEC...BMI...AND CMI WILL HAVE THE BEST CHANCE FOR EXTENDED PERIODS OF CLEARING THE REST OF THE NIGHT...AND I TRIED TO PORTRAY THAT IN THE TIMING OF CLEARING CLOUDS. CU RULE PLOTS SHOW CLEAR SKIES OR SCATTERED CLOUDS ACROSS OUR CWA TOMORROW. WILL NOT PUT ANY TEMPO BKN DECKS AS A RESULT. NO MAJOR ISSUES FOR LOW VIS OR CIGS FOR THIS TAF ISSUANCE. WINDS WILL REMAIN LIGHT AS WELL. SHIMON && .PREV DISCUSSION... ISSUED 305 PM CST THU NOV 22 2007 SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT. FAIRLY QUIET PERIOD OVER THE NEXT FEW DAYS... WITH COOL/DRY CONDITIONS PREVAILING THROUGH THE FIRST HALF OF THE WEEKEND. WE WILL BE IN THE BASE OF A RATHER FLAT LONGWAVE TROUGH THAT HAS SET UP OVER THE NORTHEASTERN CORNER OF NORTH AMERICA... WHICH WILL RESULT IN QUASI-ZONAL FLOW... KEEPING THE COLDEST AIRMASS WELL TO OUR NORTH. BIGGEST CONCERN IN THE SHORT TERM IS HOW TO HANDLE OVERNIGHT SKY CONDITIONS AND LOW TEMPERATURES. BROAD VORT MAX CURRENTLY OVER IOWA WILL SLOWLY LUMBER ITS WAY ACROSS ILLINOIS THROUGH LATE TONIGHT... BRINGING CONTINUED COOL ADVECTION ALOFT AND CYCLONIC FLOW. THIS WOULD SUPPORT CLOUD COVER CONTINUING THROUGH THE OVERNIGHT HOURS... HOWEVER THE VISIBLE SATELLITE IMAGERY SHOWS PLENTY OF HOLES IN THE OVERCAST LAYER... ASSOCIATED WITH AN ARROW TONGUE OF DRY AIR EXTENDING ACROSS WISCONSIN AND INTO THE EASTERN HALF OF OUR CWA... WHERE CLOUDS APPEAR TO BE MORE CELLULAR AND DIURNAL IN NATURE. HOWEVER... EXTENSIVE CLOUD COVER STILL REMAINS BACK ACROSS IOWA... AND THIS SHOULD HOLD TOGETHER EVEN AFTER DARK. MODEL RH FIELDS SUGGEST SOME SCATTERING OUT WITHIN THE DRY TONGUE ACROSS THE EAST THIS EVENING... BUT THICK CLOUD COVER PERSISTING FARTHER WEST. LATEST RUC IS VERY QUICK TO EXPAND CLEARING ACROSS THE AREA AFTER MIDNIGHT... BUT PREFERENCE HERE IS FOR THE MORE PESSIMISTIC 18Z NAM... WHICH SUGGESTS SOME PARTIAL CLEARING ACROSS NORTHERN AREAS OF THE CWA TOWARDS MORNING... AS THE SHEARED-OUT VORT MAX SHIFTS EAST OF THE AREA. HOWEVER... LOW LEVEL /925-850MB/ WINDS STILL EXHIBIT A MORE OF A NNW DIRECTION THROUGH 12Z. USUALLY LIKE TO SEE MORE OF A WESTERLY COMPONENT TO REALLY BRING IN THE CLEARING. OVERALL... THE SKY GRIDS KEEP THINGS MOSTLY CLOUDY ACROSS THE FAR EAST THROUGH THE NIGHT... ALTHOUGH WOULD NOT BE SURPRISED TO SEE SOME SCATTERING OUT. KEPT THINGS MORE OR LESS CLOUDY THROUGH 09Z OR SO IN THE WEST... WITH SOME SCATTERING OUT IN THE FAR NW BETWEEN 09-12Z. COULD CONTINUE TO SEE SOME SCATTERED FLURRIES ACROSS THE WEST THIS EVENING AS THE WEAK VORT MAX SLOWLY SHIFTS EASTWARD. ALREADY SEEING THIS ACROSS MUCH OF THE SOUTHWEST CORNER OF THE CWA. LATEST RUC DOES INDICATE SOME WEAK FRONTOGENETIC FORCING ACROSS THIS AREA... SHIFTING SE AFTER 00Z. BUT GIVEN THE FAIRLY WEAK FORCING AND LACK OF MOISTURE... WILL FORGO ADDING POPS AND KEEP THE MENTION OF FLURRIES IN THROUGH MIDNIGHT. OTHERWISE FEW CHANGES FRI-SAT... MAIN SYSTEM OF INTEREST IS THE COMPACT UPPER LOW DROPPING DOWN ACROSS NEVADA CURRENTLY... WHICH IS EXPECTED TO CUTOFF OVER THE DESERT SOUTHWEST BEFORE EJECTING EASTWARD... AFFECTING OUR WX IN THE SUN-MON TIME FRAME. LONG TERM...SUNDAY THROUGH THURSDAY. LONGER RANGE MODELS COMING INTO BETTER AGREEMENT WITH HANDLING OF CLOSED H5 LOW OVER THE DESERT SOUTHWEST THIS WEEKEND. 12Z ECMWF HAS TRENDED SLOWER... CLOSER TO THE GFS... WHICH HAS MAINTAINED IMPRESSIVE RUN-TO-RUN CONSISTENCY CONSIDERING RECENT PERFORMANCE. STILL THINK THE GFS MAY BE A HAIR TOO QUICK IN KICKING OUT THE CLOSED LOW... ESPECIALLY GIVEN THE MODEL TENDENCY TO DIG THE LOW SOUTHWARD A LITTLE DEEPER OVER THE PAST FEW RUNS. CONSIDERING THIS... KEPT THE HIGHEST POPS IN THE SUNDAY NIGHT-MONDAY TIME FRAME... WITH A PRETTY SHARP NW-SE GRADIENT. LATEST GFS DOES BRING QPF ACROSS THE ENTIRE AREA... BUT ATMOSPHERE WILL BE RATHER DRY THE FARTHER NORTHWEST ONE GOES FROM THE OHIO VALLEY. BEST PRECIP CHANCES/QPF WILL BE ACROSS THE FAR SOUTHEAST LATE SUNDAY NIGHT INTO EARLY MONDAY... WHEN LONG RANGE MODELS SUGGEST WEAKLY COUPLED JET STRUCTURE OVER THE OHIO VALLEY. PRIMARY PRECIP TYPE AT THIS POINT STILL LOOKS TO BE RAIN. ASSUMING THE CLOSED LOW AND THE NORTHERN STREAM KICKER TROUGH REMAIN UN-PHASED... THE NORTHERN STREAM WAVE WILL COME TOO LATE AND WILL HAVE LITTLE IN THE WAY OF MOISTURE TO WORK WITH... AND THE COLD AIR WILL FILTER IN AFTER PRECIP HAS CEASED. HARDIMAN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 555 PM CST THU NOV 22 2007 .DISCUSSION... ISSUED 305 PM CST THU NOV 22 2007 SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT. FAIRLY QUIET PERIOD OVER THE NEXT FEW DAYS... WITH COOL/DRY CONDITIONS PREVAILING THROUGH THE FIRST HALF OF THE WEEKEND. WE WILL BE IN THE BASE OF A RATHER FLAT LONGWAVE TROUGH THAT HAS SET UP OVER THE NORTHEASTERN CORNER OF NORTH AMERICA... WHICH WILL RESULT IN QUASI-ZONAL FLOW... KEEPING THE COLDEST AIRMASS WELL TO OUR NORTH. BIGGEST CONCERN IN THE SHORT TERM IS HOW TO HANDLE OVERNIGHT SKY CONDITIONS AND LOW TEMPERATURES. BROAD VORT MAX CURRENTLY OVER IOWA WILL SLOWLY LUMBER ITS WAY ACROSS ILLINOIS THROUGH LATE TONIGHT... BRINGING CONTINUED COOL ADVECTION ALOFT AND CYCLONIC FLOW. THIS WOULD SUPPORT CLOUD COVER CONTINUING THROUGH THE OVERNIGHT HOURS... HOWEVER THE VISIBLE SATELLITE IMAGERY SHOWS PLENTY OF HOLES IN THE OVERCAST LAYER... ASSOCIATED WITH AN ARROW TONGUE OF DRY AIR EXTENDING ACROSS WISCONSIN AND INTO THE EASTERN HALF OF OUR CWA... WHERE CLOUDS APPEAR TO BE MORE CELLULAR AND DIURNAL IN NATURE. HOWEVER... EXTENSIVE CLOUD COVER STILL REMAINS BACK ACROSS IOWA... AND THIS SHOULD HOLD TOGETHER EVEN AFTER DARK. MODEL RH FIELDS SUGGEST SOME SCATTERING OUT WITHIN THE DRY TONGUE ACROSS THE EAST THIS EVENING... BUT THICK CLOUD COVER PERSISTING FARTHER WEST. LATEST RUC IS VERY QUICK TO EXPAND CLEARING ACROSS THE AREA AFTER MIDNIGHT... BUT PREFERENCE HERE IS FOR THE MORE PESSIMISTIC 18Z NAM... WHICH SUGGESTS SOME PARTIAL CLEARING ACROSS NORTHERN AREAS OF THE CWA TOWARDS MORNING... AS THE SHEARED-OUT VORT MAX SHIFTS EAST OF THE AREA. HOWEVER... LOW LEVEL /925-850MB/ WINDS STILL EXHIBIT A MORE OF A NNW DIRECTION THROUGH 12Z. USUALLY LIKE TO SEE MORE OF A WESTERLY COMPONENT TO REALLY BRING IN THE CLEARING. OVERALL... THE SKY GRIDS KEEP THINGS MOSTLY CLOUDY ACROSS THE FAR EAST THROUGH THE NIGHT... ALTHOUGH WOULD NOT BE SURPRISED TO SEE SOME SCATTERING OUT. KEPT THINGS MORE OR LESS CLOUDY THROUGH 09Z OR SO IN THE WEST... WITH SOME SCATTERING OUT IN THE FAR NW BETWEEN 09-12Z. COULD CONTINUE TO SEE SOME SCATTERED FLURRIES ACROSS THE WEST THIS EVENING AS THE WEAK VORT MAX SLOWLY SHIFTS EASTWARD. ALREADY SEEING THIS ACROSS MUCH OF THE SOUTHWEST CORNER OF THE CWA. LATEST RUC DOES INDICATE SOME WEAK FRONTOGENETIC FORCING ACROSS THIS AREA... SHIFTING SE AFTER 00Z. BUT GIVEN THE FAIRLY WEAK FORCING AND LACK OF MOISTURE... WILL FORGO ADDING POPS AND KEEP THE MENTION OF FLURRIES IN THROUGH MIDNIGHT. OTHERWISE FEW CHANGES FRI-SAT... MAIN SYSTEM OF INTEREST IS THE COMPACT UPPER LOW DROPPING DOWN ACROSS NEVADA CURRENTLY... WHICH IS EXPECTED TO CUTOFF OVER THE DESERT SOUTHWEST BEFORE EJECTING EASTWARD... AFFECTING OUR WX IN THE SUN-MON TIME FRAME. LONG TERM...SUNDAY THROUGH THURSDAY. LONGER RANGE MODELS COMING INTO BETTER AGREEMENT WITH HANDLING OF CLOSED H5 LOW OVER THE DESERT SOUTHWEST THIS WEEKEND. 12Z ECMWF HAS TRENDED SLOWER... CLOSER TO THE GFS... WHICH HAS MAINTAINED IMPRESSIVE RUN-TO-RUN CONSISTENCY CONSIDERING RECENT PERFORMANCE. STILL THINK THE GFS MAY BE A HAIR TOO QUICK IN KICKING OUT THE CLOSED LOW... ESPECIALLY GIVEN THE MODEL TENDENCY TO DIG THE LOW SOUTHWARD A LITTLE DEEPER OVER THE PAST FEW RUNS. CONSIDERING THIS... KEPT THE HIGHEST POPS IN THE SUNDAY NIGHT-MONDAY TIME FRAME... WITH A PRETTY SHARP NW-SE GRADIENT. LATEST GFS DOES BRING QPF ACROSS THE ENTIRE AREA... BUT ATMOSPHERE WILL BE RATHER DRY THE FARTHER NORTHWEST ONE GOES FROM THE OHIO VALLEY. BEST PRECIP CHANCES/QPF WILL BE ACROSS THE FAR SOUTHEAST LATE SUNDAY NIGHT INTO EARLY MONDAY... WHEN LONG RANGE MODELS SUGGEST WEAKLY COUPLED JET STRUCTURE OVER THE OHIO VALLEY. PRIMARY PRECIP TYPE AT THIS POINT STILL LOOKS TO BE RAIN. ASSUMING THE CLOSED LOW AND THE NORTHERN STREAM KICKER TROUGH REMAIN UN-PHASED... THE NORTHERN STREAM WAVE WILL COME TOO LATE AND WILL HAVE LITTLE IN THE WAY OF MOISTURE TO WORK WITH... AND THE COLD AIR WILL FILTER IN AFTER PRECIP HAS CEASED. HARDIMAN && .AVIATION... ISSUED 555 PM CST THU NOV 22 2007...FOR THE 00Z TAFS STRATO CUMULUS WILL HAVE SOME CLEARING SPOTS THIS EVENING. MAKES FOR TOUGH TAF WRITING...AS THE SITES COULD GO FROM BKN035 TO SKC IN SHORT PERIODS OF TIME. RUC RH FIELDS STILL SEEM TO HAVE A GOOD HANDLE ON THE RIBBONS OF MOSTLY CLEAR SLOTS AS SEEN ON SATELLITE. THE CURRENT THIN SPOT IN THE CLOUDS EXTENDS FROM PIA TO BMI TO CMI. THE NEXT AREA OF CLEARING NORTH OF THAT IS IN SOUTHEAST WISCONSIN. THE RUC FORECAST SHOWS THAT AREA OF CLEARING DROPPING SOUTH INTO EASTERN ILLINOIS BETWEEN 03Z AND 06Z. WILL NOT TRY TO GET TOO CUTE WITH CLEARING TRENDS FOR NOW. WILL KEEP IFR CEILINGS FOR PREVAILING CONDITIONS THE REST OF THE EVENING...THEN BRING SOME CLEARING SPOTS. TOMORROW SHOULD BE MOSTLY CLEAR...WITH NO CEILINGS EXPECTED. RH DROPS OFF SIGNIFICANTLY...EVEN IN THE LOWEST LEVELS. SHIMON && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 225 PM CST THU NOV 22 2007 .DISCUSSION... 330 AM CST FORECAST FOCUS TODAY WILL CENTER ON LAKE EFFECT SNOW FOR EXTREME NORTHEAST ILLINOIS AND NORTHWEST INDIANA. UPPER LEVEL SHORT WAVE TROUGH WHICH AIDED IN LIGHT SNOW ACROSS THE FORECAST AREA LAST EVENING IS TRACKING THROUGH LOWER MICHIGAN AT THIS TIME...HOWEVER BROAD UPPER TROUGHING STILL LINGERS BACK TO THE WEST WITH A FEW ADDITIONAL SHORT WAVES EXPECTED TO BE MOVING THROUGH THE SOUTHERN GREAT LAKES REGION THROUGH TONIGHT. SURFACE LOW CURRENTLY TRACKING ACROSS CENTRAL OHIO WILL CONTINUE INTO WESTERN PENNSYLVANIA THIS MORNING. LOW LEVEL WINDS WILL CONTINUE TO BACK TO THE NORTHWEST THIS MORNING WHICH SHOULD EVENTUALLY FAVOR LAKE EFFECT SNOW SHOWERS OVER NORTHWEST INDIANA BY MID MORNING. WSR-88D HAS BEEN INDICATING SOME WEAKENING TRENDS IN RATHER BROAD DIFFUSE AREA OF PRECIP COMING OFF LAKE MICHIGAN THIS MORNING LIKELY IN RESPONSE TO A AFOREMENTIONED SHORT WAVE TROUGH HAVING TRACKED EAST OF THE AREA. HOWEVER...ACROSS CENTRAL LAKE MICHIGAN STARTING TO SEE PERHAPS MORE ORGANIZED SINGLE BAND DEVELOPING ON REGIONAL RADAR MOSAICS. LOW LEVEL LAPSE RATES WILL CONTINUE TO STEEPEN THROUGH THE MORNING AS COLD AIR ADVECTION CONTINUES WITH SHORT TERM RUC/WRF PROGS INDICATING LAKE/850 HPA DELTA TEMPERATURES ON THE ORDER OF 18 DEG CELS SHORTLY AFTER 12Z. MODIFIED SOUTHERN LAKE MICHIGAN FORECAST SOUNDINGS FOR THESE WARMER LAKE TEMPS STILL SUGGESTING LAKE INDUCED CAPES OF AROUND 500 J/KG BY MID MORNING WITH EQUIL LEVELS RISING TO 12-13K FT. RATHER IMPRESSIVE PARAMETERS FOR LAKE EFFECT SNOW BUT THE SAME FACTORS LEADING TO THESE IMPRESSIVE PARAMETERS WILL POSE SOME QUESTION AS TO PRECIP TYPE GIVEN RELATIVELY WARM/MOIST FLOW OFF THE LAKE. THIS SHOULD LIMIT ACCUMS AT LEAST INITIALLY THIS MORNING NEAR THE LAKESHORE. SHOULD TEND TO FAVOR SINGLE BANDED TYPE EVENT BY MID TO LATE MORNING...WHEN LOW LEVEL WIND PROFILES WILL BE MORE SUPPORTIVE OF THIS BAND ACROSS WESTERN LAKE COUNTY INDIANA...SHIFTING EASTWARD THROUGH LATE MORNING INTO EARLY AFTERNOON. AT THIS TIME AM NOT PLANNING MANY CHANGES TO GOING LAKE EFFECT HEADLINES. FAR EASTERN COOK AND WILL COUNTIES WILL HAVE A SHORT WINDOW OF OPPORTUNITY FOR ACCUMS AS MORE IMPRESSIVE LOW LEVEL LAPSE RATES ARRIVE RIGHT AS WIND PROFILES WILL BECOME MORE FAVORABLE FOR LAKE EFFECT SNOW EASTWARD INTO NORTHWEST INDIANA. THUS...WILL DROP LAKE EFFECT SNOW ADVISORY FOR FAR SOUTHEAST COOK/EASTERN WILL COUNTIES. WILL RANGE ACCUMS FROM AROUND AN INCH ACROSS FAR SOUTHEAST COOK/FAR EASTERN WILL COUNTY...TO 2 TO 4 INCHES ACROSS LAKE CO IND AND PORTER COUNTIES WITH LOCALLY HIGHER AMOUNTS POSSIBLE DUE TO EXPECTED SINGLE BANDED CONVECTIVE NATURE. A FEW INCHES OF SNOW ALSO POSSIBLE TODAY DOWNWIND OF THE LAKE ACROSS NORTHERN JASPER/NEWTON COUNTIES. ELSEWHERE...VARIABLE CLOUDINESS EARLY THIS MORNING SHOULD GIVE WAY TO MOSTLY CLOUDY SKIES DUE TO INFLUENCE OF UPSTREAM SHORT WAVES APPROACHING FROM IA/NRN MO WITH A FEW FLURRIES POSSIBLE. HIGHS IN THE MID 30S ALSO SEEMS REASONABLE FOR MOST LOCATIONS TODAY WITH NOT MUCH CHANGE FROM MORNING READINGS DUE TO COLD ADVECTION. BY THIS EVENING LOW LEVEL WINDS WILL CONTINUE TO BACK NORTHWEST WHICH SHOULD TAKE LAKE EFFECT SNOW THREAT EAST OF PORTER COUNTY...SO 02Z ENDING TIME TO THE LAKE EFFECT SNOW ADVISORY WILL BE LEFT AS IS. LAST IN THE SERIES OF UPSTREAM SHORT WAVES SHOULD BE PASSING THROUGH THE FORECAST AREA LATE TONIGHT WHICH SHOULD ALLOW FOR CLEARING TREND OVERNIGHT AND COLD OVERNIGHT TEMPS. CLEARING SKIES AND WEAKENING WINDS SHOULD ALLOW FOR QUITE COLD TEMPS TONIGHT...FROM UPPER TEENS ACROSS NORTHWEST ILLINOIS TO THE LOWER TO MID 20S ACROSS NORTHWEST INDIANA WHERE AIR MASS WILL BE MODIFIED FROM TODAY`S FLOW OFF THE LAKE. ON FRIDAY...SURFACE HIGH WILL MOVE ACROSS THE MID MS RIVER VALLEY AND LACK OF ANY SIG THERMAL ADVECTION WILL RESULT IN ANOTHER COLD DAY WITH HIGHS IN THE MID TO UPPER 30S...ALTHOUGH WILL FINALLY GET INTO SOME SUNSHINE. ON SATURDAY...ANOTHER UPPER TROUGH APPROACHES THE REGION FROM SOUTHERN CANADA. UPPER LEVEL Q-VECTORS SUPPORT STRONGER UPPER FORCING REMAINING ACROSS SOUTHERN CANADA. MAY HAVE A FEW SPRINKLES OR FLURRIES AS WEAK ASSOCIATED LOW LEVEL TROUGH MOVES THROUGH THE REGION SATURDAY...BUT WILL KEEP DRY AT THIS TIME AND JUST NUDGE UP CLOUDS A BIT. ONLY CHANGE MADE TO THE EXTENDED FORECAST WAS TO DELAY TIMING OF NEXT PRECIP CHANCE...AS CUT OFF LOW ACROSS THE SOUTHWEST US SHOULD GET REINGESTED IN THE WESTERLIES. NEW 00Z DATA WOULD SUGGEST CHANCE OF -RA ON MONDAY...BUT STILL MUCH UNCERTAINTY IN REGARDS TO THE TRACK OF THIS UPPER LOW...SO WILL KEEP THE POPS LOW FOR THIS PERIOD. MARSILI && .AVIATION... A WEAK SURFACE TROUGH IS PASSING THROUGH NORTHEAST ILLINOIS. THE TROUGH LIES FROM BENTON HARBOR MICHIGAN TO ROCKFALLS ILLINOIS AT 1700 UTC. THIS IS WHERE A BAND OF SNOW IS OCCURRING. THERE WAS LIFR VISIBILITY AT MIDWAY FOR A SHORT TIME. THE LAKE HAS SOME INFLUENCE FOR THIS SNOW. THE SNOW WILL AFFECT MDW AND GYY. THE TROUGH WILL MOVE SOUTH AND THE SNOW IS EXPECTED TO END THIS AFTERNOON. WE EXPECT A BROKEN CEILING OF STRATOCUMULUS CLOUDS THE REST OF THE AFTERNOON. TONIGHT...THE CLOUDS WILL BECOME SCATTERED. AS A HIGH MOVES INTO THE OHIO VALLEY BY FRIDAY EVENING THE WIND IS FORECAST TO BECOME MORE WESTERLY FRIDAY MORNING. && .MARINE... THE SURFACE LOW CONTINUES TO MOVE NORTHEAST FROM EASTERN NEW YORK TOWARDS NEWFOUNDLAND. HIGH PRESSURE IS EXPECTED TO MOVE INTO THE CENTRAL PLAINS TONIGHT THE PRESSURE GRADIENT ACROSS LAKE MICHIGAN IS EXPECTED TO DECREASE. A NORTHWEST WIND WILL BE 10 TO 20 KNOTS. SNOW SHOWERS WILL CONTINUE AS AN UPPER AIR TROUGH MOVES ACROSS THE GREAT LAKES. THE WAVES WILL DECREASE OVERNIGHT. THE SOUTH PORTION OF LAKE MICHIGAN WILL HAVE HIGHER WAVES THAN THE NORTH BECAUSE OF THE FETCH OF THE NORTHWEST TO NORTH WIND OVER THE LAKE. HIGH PRESSURE WILL MOVE ACROSS THE OHIO VALLEY SATURDAY AND SUNDAY. THE INCREASE PRESSURE GRADIENT OVER LAKE MICHIGAN FROM THE HIGH AND A LOW OVER HUDSON BAY WILL GIVE A 25 TO 30 KNOTS SOUTHWEST WIND SATURDAY. BY LATE SUNDAY NIGHT A LOW WILL MOVE INTO ONTARIO WHILE A LOW DEVELOPS IN ARKANSAS. THIS LOW IN ARKANSAS WILL MOVE INTO LAKE ONTARIO BY MONDAY NIGHT. && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE LM...SMALL CRAFT ADV FOR ILLINOIS NEARSHORE WATERS THROUGH TONIGHT. SMALL CRAFT ADV FOR INDIANA NEARSHORE WATERS THROUGH FRIDAY MORNING. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1114 PM CST WED NOV 21 2007 .DISCUSSION... ISSUED 859 PM CST WED NOV 21 2007 THE DEFORMATION ZONE OF SNOW SET UP PRIMARILY ACROSS IOWA. ACCUMULATING SNOW HAS NOT AFFECTED OUR CWA TOO MUCH YET. A CALL TO THE KNOX COUNTY SHERIFF INDICATED LITTLE SNOW ACCUMULATION THERE TO THIS POINT. THERE WERE A FEW ACCIDENTS ON THE ROADS...SO SOME ICING MAY BE OCCURRING. THE CHANGE OF RAIN TO SNOW HAS BEEN CONFINED MAINLY TO AREAS WEST OF THE ILLINOIS RIVER. THE DEFORMATION ZONE IS EXPECTED TO PROGRESS EASTWARD...WITH THE SOUTHERN EDGE OF THE ACCUMULATING SNOW SHOWERS EXPECTED TO REMAIN NORTH OF A LINE FROM MACOMB TO BLOOMINGTON. GALESBURG AND LACON WILL HAVE THE BEST CHANCE FOR A HALF INCH OF SNOW...WHILE PEORIA MOST LIKELY WILL SEE A DUSTING TO A COUPLE OF TENTHS. LITTLE ADDITIONAL SNOW ACCUMULATION WILL OCCUR AFTER MIDNIGHT...SO WHATEVER STICKS ON THE GROUND UNTIL THEN WILL BE ALL FOR MEASURABLE SNOW. AS THE SURFACE LOW MOVES FROM CENTRAL INDIANA TO OHIO THE REST OF THE NIGHT...A REGION OF LIFT WILL MOVE ACROSS THE REST OF OUR CWA. WE MAY SEE A FEW RAIN OR SNOW SHOWERS BETWEEN MIDNIGHT AND 6 AM EAST OF I-55. DRIZZLE WILL BE THE MAIN FEATURE SE OF I-55 UNTIL THE MID LEVEL MOISTURE PROGRESSES ACROSS THAT AREA AND PROVIDES SOME ICE CRYSTALS FROM ABOVE TO DROP INTO THE LOW MOISTURE LAYER. THAT WILL HELP PRODUCE RAIN OR SNOW SHOWERS...INSTEAD OF DRIZZLE. BRISK NORTH WINDS WILL CONTINUE THE REST OF THE NIGHT...MAKING IT FEEL MUCH COLDER THAN THE LOWER 30S. TEMPS ACROSS MUCH OF IOWA ARE STILL IN THE 30S...SO OUR FORECAST LOWS OF LOW TO MID 30S LOOK GOOD. SOME UPPER 20S MIGHT OCCUR IN KNOX COUNTY IF ANY CLEAR SPOTS DEVELOP IN THE CLOUDS LATE TONIGHT. OVERALL...THE MAIN CHANGES TO THE GRIDS WERE TO THE WEATHER AND POPS. THE REST LOOKS ON TRACK. UPDATED INFORMATION ALREADY AVAILABLE. SHIMON && .AVIATION... ISSUED 1115 PM CST WED NOV 21 2007...FOR THE 06Z TAFS THE DEFORMATION SNOW/RAIN BAND HAS MOSTLY DISSIPATED ACROSS OUR CWA...WITH THE MAIN PRECIP NOW NORTH OF OUR CWA. A SMALL LINGERING BAND OR RAIN OVER OUR CWA IS ABOUT TO DEPART DEC AND AFFECT CMI...OTHERWISE PRECIP HAS QUIETED DOWN AT THE OTHER TAF SITES. THE SURFACE LOW HAS MOVED TO NEAR THE INDIANA...OHIO BORDER...AND ISENTROPIC DOWNGLIDE WILL BEGIN TO TAKE ITS TOLL ON ANY ADDITIONAL CHANCES OF MEASURABLE PRECIPITATION. FLURRIES OR DRIZZLE WILL MOST LIKELY BE ALL THAT REMAINS AFTER THE NEXT FEW HOURS. LIFR LOW CLOUDS HAVE ALREADY LIFTED UP TO IFR LEVELS FOR ALL SITES EXCEPT CMI. CMI SHOULD CLIMB UP THERE SOON AS WELL. BY MORNING...CIGS MAY LIFT TO MVFR OR VFR IN SPOTS. WILL TEMPO IN SOME VFR CIGS FOR PIA AND SPI AT LEAST. NORTH WINDS WILL CONTINUE TO GUST TO 30 MPH FOR AT LEAST ANOTHER 3 TO 4 HOURS. BY MORNING...GUSTS SHOULD HAVE DIMINISHED. NO MAJOR VISIBILITY ISSUES ARE EXPECTED FOR THIS FORECAST. SHIMON && .PREV DISCUSSION... ISSUED 301 PM CST WED NOV 21 2007 SHORT TERM...TONIGHT THROUGH SATURDAY... SHARP BUT WAVY COLD FRONT HAS JUST PASSED THROUGH PARIS AND EFFINGHAM...BUT IS NOT BREAKING ANY SPEED RECORDS. ONE WAVE ALONG THE FRONT IS NOW LOCATED JUST EAST OF EFFINGHAM...WHILE ANOTHER ONE IS APPROACHING FROM SOUTHWEST OF SALEM. THE FRONT WILL LIKELY NOT CLEAR THE SOUTHEASTERN COUNTIES UNTIL AROUND 7PM THIS EVENING AS THE SALEM WAVE RIPPLES NORTHEASTWARD INTO INDIANA. INSTABILITY HAS BEEN INCREASING AHEAD OF THE FRONT THIS AFTERNOON...WITH SURFACE-BASED LIFTED INDICES AROUND ZERO AT LWV AND STRONGER FURTHER SOUTHWEST. CONVECTION WILL CONTINUE TO INCREASE ALONG THE FRONT AND COME INTO THE INTERSTATE 70 CORRIDOR THIS EVENING. WOULD NOT BE SURPRISED TO SEE SOME SMALL HAIL IN THE STRONGER STORMS...BUT NO ORGANIZED SEVERE IS ANTICIPATED AT THIS TIME. MEANWHILE TO THE NORTHWEST...RAIN IS IN THE PROCESS OF CHANGING TO A MIXTURE OF LIGHT SNOW AND LIGHT SLEET IN THE FAR NORTH AND NORTHWEST COUNTIES UP AROUND GALESBURG. QUINCY/BURLINGTON/MACOMB ARE ALL REPORTING LIGHT SNOW NOW. WITH THE VERY SLOW MOVEMENT OF THE FRONT THIS AFTERNOON...COLD ADVECTION HAS ALSO BEEN VERY SLOW. AS THE AFOREMENTIONED WAVE MOVES INTO INDIANA...SURFACE WINDS WILL BACK AROUND TO NORTHWESTERLY AND THE RAIN/SNOW LINE SHOULD START PROGRESSING SOUTHEASTWARD. FORECAST SOUNDINGS FROM THE RUC40 MODEL SUGGEST THAT THERE WILL BE A PERIOD OF A COUPLE HOURS DURING TRANSITION TIME THAT A FAIRLY DEEP LAYER 2K-8K FT WILL BE BOUNCING RIGHT ALONG THE FREEZING LINE...SO WILL CONTINUE THE MENTION OF LIGHT SLEET DURING PRECIPITATION PHASE CHANGE. TEMPERATURES AT GROUND LEVEL SHOULD STAY ABOVE FREEZING THIS EVENING...POSSIBLY GETTING DOWN TO 32F AT GALESBURG BY MIDNIGHT. PRECIPITATION SHOULD BE ENTIRELY SNOW UP THERE BY THEN. THIS TREND SHOULD CONTINUE... WITH RAIN CHANGING TO SNOW BEFORE SURFACE TEMPERATURES GET DOWN TO FREEZING...AND THUS MITIGATING THE THREAT FOR FREEZING RAIN/ICING. THE FREEZING LINE SHOULD ONLY PROGRESS TO THE INTERSTATE 55 CORRIDOR BY SUNRISE. AS FOR SNOW AMOUNTS...EXPECT LITTLE OR NO ACCUMULATIONS SOUTH OF A TAYLORVILLE TO PARIS LINE. EVERYONE NORTH OF THERE SHOULD BE LESS THAN ONE HALF INCH...EXCEPT POSSIBLY 0.5-1.0 INCH FROM MACOMB TO BLOOMINGTON AND NORTHWARD CLOSER TO THE MID LEVEL DEFORMATION ZONE THAT WILL BE SWEEPING FROM EASTERN IOWA THROUGH NORTHERN ILLINOIS. AFTER A SLIGHT CHANCE OF FLURRIES THURSDAY MORNING...EXPECT MAINLY DRY AND COLDER CONDITIONS THROUGH THE END OF THE WEEK. INITIAL STRONG NORTH WINDS TONIGHT AND EARLY THURSDAY WILL DECREASE AS THE SURFACE LOW DEPARTS THE MIDWEST AND THE PRESSURE GRADIENT RELAXES BY MIDDAY THURSDAY. THERE SHOULD BE TOO MUCH OF A TEMPERATURE RISE ON THURSDAY...WITH HIGHS RANGING FROM THE MID 30S TO LOWER 40S. LONG TERM...SUNDAY THROUGH WEDNESDAY... THE LONGER RANGE MODELS ARE IN SURPRISINGLY DECENT AGREEMENT ON SLOWING DOWN THE UPPER LOW THAT WILL BE MIGRATING ACROSS THE SOUTHERN PLAINS THEN EJECTING TOWARD ILLINOIS EARLY NEXT WEEK. THE UPPER LOW IS NOW EXPECTED TO PROGRESS INTO THE NORTH TEXAS AREA BY LATE SUNDAY...THEN MOVE NORTHEAST TO SOUTHERN ILLINOIS BY 12Z MONDAY. THUS THE BEST PROSPECTS FOR PRECIPITATION APPEAR TO BE SUNDAY NIGHT INTO MONDAY NIGHT. FORECAST SOUNDINGS SUGGEST THAT ALL THE PRECIPITATION SHOULD BE RAIN AND THIS MAKES SENSE GIVEN ALL OF THE WARM ADVECTION AHEAD OF THE SYSTEM. IT COULD BE CLOSE IN THE NORTHWEST AS THE PRECIPITATION ENDS MONDAY NIGHT...BUT THE RISK APPEARS TOO SLIM TO MENTION THIS FAR IN ADVANCE. 04 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 115 AM EST THU NOV 22 2007 .AVIATION... MAIN FOCUS ON TIMING OF DEFORMATION ZONE COINCIDENT WITH INCREASED UVM SUFFICIENT FOR CHANGEOVER TO SNOW/TEMPO LIFR CONDITIONS LWRG IN SN/BR AS IT SLIDES EWD THIS AM. RUC SEEMS TO HAVE GOOD BEAT ON FEATURE AND FOLLOWED CLOSELY...AIR TEMP AT KIWX 35.2 DEGREES ATTM WITH SNOW JUST TO NORTH OF OFFICE. AS WINDS CONTINUE TO BACK SLIGHTLY AT KFWA NEXT COUPLE OF HOURS CHANGE TO SNOW CLOSE AT HAND. OTHER FACTOR LATER THIS AFTERNOON AND ESPECIALLY TONIGHT AT KSBN WILL BE LAKE EFFECT SNOW POTENTIAL. INITIALLY FETCH NRLY AND SINGLE BAND SHOULD SET UP WEST OF AIRFIELD...HOWEVER AS NIGHT PROGRESSES AND WINDS BACK FURTHER...BAND TO SHIFT/PERHAPS TRANSITION INTO MULTIBANDED EVENT AS WELL AND LIKELY BRING LOWERING CONDITIONS TOWARD END OF FCST PERIOD. && .UPDATE... RAIN BEGINNING TO CHANGE TO SNOW OVER NWRN PORTIONS OF CWA. THIS IS A LITTLE LATER THAN EARLIER FCSTS. THUS, HAVE UPDATED FCSTS TO LOWER SNOW ACCUMULATIONS A BIT OVERNIGHT. CONTD WITH LAKE EFFECT SNOW WATCH FOR THURSDAY AS APPEARS AIRMASS WILL BE COLD ENOUGH WITH NORTHERLY FLOW FOR A SINGLE BAND TO DEVELOP AND AFFECT THE AREA SOUTH OF LM MUCH OF THE DAY WITH WIND FLOW GRDLY BACKING CAUSING BANDS TO SHIFT EASTWARD ACROSS NRN INDIANA AND SW MI IN THE AFTN. && .PREV DISCUSSION... /ISSUED 741 PM EST WED NOV 21 2007/ UPDATE... FCST GRIDS LOOK ON TRACK AS CONTD CAA SHOULD CAUSE RAIN TO CHANGE OVER TO SNOW FM NW-SE ACROSS THE CWA BETWEEN 03Z-09Z. UPDATED ZONES JUST TO FRESHEN WORDING. PREV DISCUSSION... /ISSUED 705 PM EST WED NOV 21 2007/ MARINE... LOW OVER SWRN INDIANA DEEPENING A LITTLE QUICKER THAN INDICATED BY RECENT MODEL RUNS. AS LOW MOVES NE THIS EVE...ISALLOBARIC GRADIENT SHOULD ENHANCE WINDS OVER SRN LM. SUSTAINED WINDS APPROACHING GALE FORCE WITH GUSTS INTO THE U30S AT 23Z. EXPECT THIS TO CONT OR INCREASE SLIGHTLY THROUGH 06Z THAN GRDLY DIMINISH LATE TONIGHT. THUS, HAVE ISSUED A GALE WARNING FOR THE NSH WATERS OVERNIGHT. PREV DISCUSSION... /ISSUED 444 PM EST WED NOV 21 2007/ SHORT TERM...TONIGHT THROUGH TOMORROW NIGHT. A LOW PRESSURE STRETCHED FROM WESTERN NEW YORK THROUGH CENTRAL INDIANA AND ON DOWN TO ARKANSAS. THIS WILL MOVE ON TO THE EAST COAST STATES TONIGHT AND FURTHER EASTWARD THROUGH TOMORROW. ALSO TOMORROW HIGH PRESSURE WILL BE MOVING THIS WAY FROM THE WEST AND AN UPPER LEVEL TROUGH WILL BE MOVING THIS WAY FROM THE NORTH. THE UPPER TROUGH WILL THEN MOVE THROUGH TOMORROW NIGHT...POSSIBLY ALTERING THE PATH OF THE LAKE EFFECT SNOW FOR A SHORT TIME...AS THE HIGH PRESSURE ADVANCES EVEN CLOSER. AS THE LOW PRESSURE TROUGH HAS BEEN ADVANCING EASTWARD TODAY...AREAS BEHIND IT HAVE SEEN DROPPING TEMPERATURES. PRETTY MUCH THE ENTIRE CWA HAS ALREADY DROPPED INTO THE 40S WITH MUCH OF THE CWA IN THE LOWER 40S. AS MORE AND MORE OF THE COLDER AIR PUSHES INTO THE CWA THIS EVENING AND OVERNIGHT...AREAS WILL SEE THE RAIN CHANGE OVER TO SNOW FROM THE NORTHWEST TO THE SOUTHEAST. DURING THIS CHANGE OVER THERE MAY BE A VERY BRIEF TIME OF SLEET...BUT IF SLEET DOES OCCUR...IT IS EXPECTED TO NOT LAST LONG. MODEL SOUNDINGS AND THICKNESS VALUES INDICATE THAT THE RAIN WILL CHANGE OVER TO SNOW AT SBN ROUGHLY AROUND 03-04Z AT SBN...07-08Z AT FWA...AND 08-10Z AT AOH. ABOUT ONE TO TWO INCHES OF SNOW CAN BE EXPECTED ACROSS THE CWA TONIGHT. BUT THERE IS ONE UNKNOWN ITEM WITH THE SNOW ACCUMULATING...AND THAT IS THE WARM GROUND. AT THIS TIME OF YEAR THE GROUND IS STILL RELATIVELY WARM AND ALSO WITH THE GROUND SATURATED FROM TODAY/S RAINFALL...HOW LONG IT WILL TAKE FOR THE SNOW TO BEGIN STICKING IS IN QUESTION FOR TONIGHT AND TOMORROW. THE PRESSURE GRADIENT IS GOING TO BE FAIRLY TIGHT TONIGHT RESULTING IN A STRONG WIND OUT OF THE NORTH. THEN LATE TONIGHT/EARLY TOMORROW MORNING AS THE SYNOPTIC SNOW IS LEAVING THE EASTERN PART OF THE CWA LAKE EFFECT SNOW WILL BEGIN IN THE NORTHWESTERN PART. WITH THE WIND OUT OF DUE NORTH TO START OUT TOMORROW MORNING...THE LAKE EFFECT SNOW IS EXPECTED TO HIT DUE SOUTH OF LAKE MICHIGAN FIRST. BUT THEN AS THE WIND TURNS A LITTLE MORE NORTHWESTERLY LATER TOMORROW THROUGH TOMORROW NIGHT...THE LAKE EFFECT SNOW IS EXPECTED TO TURN MORE SOUTHEASTERLY FROM THE LAKE. THE POTENTIAL IS THERE FOR LAKE EFFECT AREAS TO SEE SEVERAL INCHES OF SNOW WITH LAKE MICHIGAN STILL BEING SO WARM WITH SUCH COLD AIR MOVING OVER IT...BUT LIKE MENTIONED ABOVE THE PROBLEM IS HOW MUCH THE WARM/WET GROUND IS GOING TO PLAY INTO THE SITUATION. SO THE LAKE EFFECT WATCH WILL BE LEFT AS A WATCH FOR NOW INSTEAD OF UPGRADING TO AN ADVISORY WITH THIS WARM GROUND GIVING LOWER CONFIDENCE THAN USUAL. WITH THE OVERCAST SKIES TOMORROW AND THE SNOWFALL...TEMPERATURES ARE NOT EXPECTED TO RISE THAT MUCH TOMORROW. LONG TERM...FRIDAY THROUGH WEDNESDAY. FRI-SUN...CONFIDENCE IS RELATIVELY HIGH DURING THIS PERIOD WITH MODELS AGREEING ON A SPLIT FLOW REGIME WITH A SFC HIGH TRANSLATING FROM THE OH VALLEY EASTWARD INTO THE MIDDLE ATLANTIC. LAKE EFFECT SNOW ACTIVITY WILL RAPIDLY DECREASE IN COVERAGE/INTENSITY LATE THU NIGHT INTO FRI MORNING WITH HEIGHT RISES AND 1000-700MB WINDS BACKING TO THE WSW BY FRI AFTN. A NRN STREAM SHRTWV WILL TRACK THRU THE UPPER MIDWEST AND GREAT LAKES LATE SAT. EXPECT THIS SHRTWV TO COME THRU DRY AS BEST DYNAMICS STAY WELL NORTH. SUN WILL LIKELY FEATURE SOME INCREASE IN MID/HIGH LEVEL CLOUDS AS THE WELL ADVERTISED SRN STREAM SYSTEM TAKES SHAPE OVER THE SRN PLAINS/LOWER MS VALLEY. OTHERWISE...A WARM-UP IS EXPECTED WITH A RETURN TO NORMAL TEMPS BY SUNDAY. MON-WED...MAIN CONCERN IS THE TRACK/STRENGTH/TIMING OF SRN STREAM UPPER LOW FCST TO IMPACT THE OH VALLEY AND POSSIBLY THE SRN GREAT LAKES SUN NIGHT THRU MON NIGHT. THIS HINGES ON THE DEPTH AND STRENGTH OF ADDITIONAL PACIFIC ENERGY PROGGED TO PROGRESS INTO THE NORTHWEST CONUS AND ITS INTERACTION WITH A POLAR VORTEX IN CENTRAL CANADA. EXPECT JUST RAIN WITH THIS SYSTEM AS MODELS HAVE COME INTO GENERAL AGREEMENT ON WARMER THERMAL FIELDS LATE SUN NIGHT INTO MONDAY. HOWEVER...THERE ARE STILL DIFFERENCES REGARDING THE TRACK/STRENGTH. THE ECMWF REMAINS THE STRONGER...FASTER...AND FARTHER NW SOLUTION...PRODUCING DEFORMATION ZONE RAINS SUN NIGHT INTO MON. CONTINUE TO FAVOR SLIGHTLY SLOWER SOLUTIONS OF THE OPERATIONAL GFS...MANY GFS ENSEMBLE MEMBERS...GEFS...AND CANADIAN WHICH HINT AT THE BEST CHC OF RAIN BEING DURING THE DAY ON MON. AS A RESULT...HAVE LOW CHC POPS ON MONDAY WITH SUBSEQUENT SHIFTS POSSIBLY NEEDING TO ADD POPS TO MONDAY EVENING. FOR TUE-WED...THINK THE 12Z ECMWF/GFS IS TOO FAR SOUTH WITH VORT LOBE UNDERCUTTING STRONG UPPER-LOW OVER CENTRAL CANADA...RESULTING IN THE SOUTHERN GREAT LAKES BEING ON THE SOUTHERN FRINGE OF AN ARCTIC AIRMASS. PREFER FARTHER NORTH PLACEMENT OF ARCTIC AIRMASS SO WILL REMAIN NEAR CLIMO AND HPC GUIDANCE ON DAYS 6/7. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...LAKE EFFECT SNOW WATCH FROM 6 AM CST THURSDAY THROUGH THURSDAY EVENING FOR INZ012. LAKE EFFECT SNOW WATCH FROM 7 AM EST /6 AM CST/ THURSDAY THROUGH FRIDAY MORNING FOR INZ003-004. MI...LAKE EFFECT SNOW WATCH FROM 7 AM EST THURSDAY THROUGH FRIDAY MORNING FOR MIZ077. LAKE EFFECT SNOW WATCH FROM THURSDAY AFTERNOON THROUGH FRIDAY MORNING FOR MIZ078. OH...NONE. LM...SMALL CRAFT ADVISORY FROM 4 AM THURSDAY TO 11 AM EST FRIDAY FOR LMZ043-046. GALE WARNING UNTIL 4 AM EST THURSDAY FOR LMZ043-046. && $$ SHORT TERM...LOTHAMER LONG TERM...STEINWEDEL UPDATE...TAYLOR MARINE...TAYLOR AVIATION...MURPHY in AREA FORECAST DISCUSSION...CORRECTION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 255 PM CST THU NOV 22 2007 .SYNOPSIS... QUIET BUT COLD WEATHER WILL BE SEEN FOR MUCH OF THE HOLIDAY WEEKEND AS HIGH PRESSURE MOVES THROUGH THE REGION. A SIGNIFICANT STORM SYSTEM IS EXPECTED TO AFFECT PART OF THE MIDWEST SUNDAY NIGHT INTO MONDAY. THIS STORM SYSTEM HERALDS THE START OF AN UNSETTLED WEATHER PATTERN FOR NEXT WEEK. && .SHORT TERM...TONIGHT AND FRIDAY... RUC HAS A MESOSCALE BAND OF FORCING REMAINING ACROSS THE SOUTH THIRD THIS EVENING BEFORE DISSIPATING. SAID FEATURE HAS ALLOWED FLURRIES AND -SN TO PERSIST THROUGH THE DAY. EXPECT TO SEE SOME FLURRIES OR -SN INTO THE EVENING BEFORE DISSIPATING. FRONTOGENETICAL FORCING DEVELOPS ACROSS THE REST OF THE AREA LATE THIS AFTERNOON/EVENING WHICH SHOULD ALLOW SOME FLURRIES TO DEVELOP. CLOUDS SHOULD START TO SLOWLY CLEAR IN THE WEST 03Z-06Z WITH THE BACK EDGE OF THE CLOUDS EAST OF THE MISSISSIPPI RIVER BY 12Z. TEMPERATURES SHOULD APPROACH OR ACHIEVE SINGLE DIGITS OVER THE DEEPER SNOW IN THE NORTHWEST PART OF THE CWFA. QUIET WX FRIDAY AS CANADIAN HIGH PRESSURE MOVES ACROSS THE AREA. TEMPERATURES SHOULD BE 5-7 DEGREES WARMER. ...08... .LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY... ACTIVE PATTERN CONTINUES...SEASONABLY COLD WITH ANOTHER STORM SYSTEM MONDAY AND AGAIN MID TO LATE NEXT WEEK. PREFER ECMWF AS MORE STABLE AND ACCURATE RUN-TO-RUN. FRIDAY NIGHT THROUGH SUNDAY...QUIET WEATHER WITH SLOWLY MODERATING TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL WITH PERIODS OF MID AND HIGH CLOUDS AS CANADIAN HIGH PRESSURE SLOWLY MOVES EAST AHEAD OF WESTERN US TROUGH DIGGING INTO TEXAS. KEPT MIN TEMPS NEAR GUIDANCE WITH POTENTIAL FOR MIN TEMPS A CATEGORY BELOW OR MORE...ESPECIALLY NW 1/3 WITH SNOW COVER IF CLOUDS CLEAR. SUNDAY NIGHT THROUGH MONDAY NIGHT...SOLUTIONS CONVERGING TO SOUTHERN PLAINS LOW TO LIFT NE OVER AT LEAST SE 1/2 AREA AHEAD OF NEXT SHOT OF CANADIAN AIRMASS. LARGE SCALE FORCING SUPPORTS UPPING POPS TO SLIGHT CHANCE NW AND CHANCE SE SECTIONS. PREFER ECMWF THERMAL FIELDS WHICH HAVE BEEN CONSISTENT FOR GOOD EVAPORATIVE COOLING TO ALLOW FOR RAIN AND SNOW MIXTURE. TRENDS SUGGEST THIS BETTER CLARIFIED NEXT 24 HOURS. HAVE UPDATED HAZARDOUS WEATHER OUTLOOK AS SYSTEM TO PRODUCE SEASONABLY MODERATE TO HEAVY AMOUNTS IN CASE ENOUGH COOLING POTENTIAL TO PRODUCE SOME ACCUMULATIONS AS SFC LOW LIFTS NE AND COLDER AIR ALSO MOVES IN. NOTABLE GFS HAS TRENDED COLDER PAST THREE RUNS WITH LOWER LEVEL THERMAL FIELDS. TEMPS A CHALLENGE WITH MIN/MAX TEMPS A CATEGORY TOO LOW/HIGH IF CLOUDS AND PRECIPITATION COME IN AS SUGGESTED. TUESDAY AND WEDNESDAY...CANADIAN HIGH PRESSURE TO BRING MORE COLDER AIR IN WITH THERMAL FIELDS FROM ECMWF AND A LESSER EXTENT GFS/GEFS SUGGESTING MIN TEMPS NEED LOWERING AT LEAST ANOTHER 2 TO 5 DEGREES AND MAX TEMPS MAY BE A FEW DEGREES TOO MILD AS WELL...ESPECIALLY IF MORE SNOWFALL OCCURS. DAYS 8-15.../NOV 29-DEC 7/...ALL SOLUTIONS CONTINUE EXTREMELY ACTIVE PATTERN WITH FAVORABLE REGIME FOR MAJOR STORMS PASS NEAR TO OVER UPPER MIDWEST WITH INTERVALS OF COLD ARCTIC AIR TO IMPACT AREA. MODERATE TO STRONG SYSTEM SUPPORTED CIRCA NOV 29 WITH RISK OF ACCUMULATING SNOW AND ANOTHER SIGNIFICANT SYSTEM...SOME TECHNIQUES SUGGEST TO BE STRONG TO EXTREMELY STRONG CIRCA DEC 1-3 PERIOD WITH LOTS OF SNOW AND/OR RAIN. APPEARS REGION TO REMAIN SUSCEPTIBLE FOR INCREASINGLY COLDER ARCTIC AIR INTRUSIONS WELL INTO THE FIRST WEEK OF DECEMBER. ..NICHOLS.. && .AVIATION... 850-500MB FRONTOGENETICAL FORCING AND LOW LEVEL F VECTOR CONVERGENCE HAS RESULTED IN A PERSISTENT BAND OF -SN/--SN AROUND THE KBRL AREA. 18Z RUC SHOWS THIS FEATURE PERSISTING INTO THE EVENING HOURS. THUS WILL KEEP 2-3KFT CIGS GOING WITH VSBYS IMPROVING TO 6SM OR BETTER STARTING AT 22Z. LOW CLOUDS TO BREAK UP BETWEEN 03Z-06Z. ALL OTHER TAF SITES TO STAY P6SM WITH CIGS JUST ABOVE 3KFT WITH SCATTERED --SN. OTHER TAF SITES TO BREAK UP CLOUDS BETWEEN 03Z-06Z. ...08... && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ 08/NICHOLS ia AREA FORECAST DISCUSSION...UPDATE... NATIONAL WEATHER SERVICE QUAD CITIES IA IL 1106 AM CST THU NOV 22 2007 .UPDATE... PERSISTENT BAND OF -SN ACROSS THE SOUTH THIRD IS ASSOCIATED WITH NICE 1000-850MB F VECTOR CONVERGENCE AND 850-500MB FRONTOGENESIS. 15Z RUC SHOWS THIS FEATURE PERSISTING THROUGH THE AFTERNOON ROUGHLY ALONG HIGHWAY 30. WITH SEVERAL OB SITES REPORTING 3-5SM...HAVE UPDATED THE FORECAST TO MENTION LIGHT SNOW. ...08... /PREVIOUS DISCUSSION/ .SYNOPSIS... STRONG COLD ADVECTION...AND CYCLONIC FLOW CONTINUES EARLY THIS MORNING ACROSS THE MIDWEST...AND SHOULD BE THE DOMINANT WEATHER FOR TODAY. A HIGH PRESSURE RIDGE IS LOCATED OVER THE PLAINS...AND THIS WILL WORK TOWARDS THE AREA FOR TONIGHT. SNOWFALL TOTALS YESTERDAY WERE CONFINED TO LOCATIONS WEST OF A LINE FROM MEMPHIS MO...TO DAVENPORT...TO JO DAVIESS COUNTY ILLINOIS. THE PRIMARY AXIS OF SIGNIFICANT SNOW...3 TO 4.5 INCHES...IS FELL FROM NEAR BELLE PLAINE IOWA...THROUGH LINN...DELAWARE AND DUBUQUE COUNTIES. THIS WILL ALMOST CERTAINLY LAST THROUGH THE DAY TODAY WITHOUT MELTING...AND WILL BE ADDRESSED IN THE TEMPERATURE FORECAST TODAY AND TONIGHT. && .SHORT TERM...TODAY AND TONIGHT... CLOUDS LOOK TO REMAIN IN PLACE MUCH OF THE DAY TODAY AS A VORT CENTER ROTATES ACROSS THE UPPER MIDWEST IN THE CYCLONIC FLOW. THIS MAY ALLOW FOR SOME FLURRIES FROM TIME TO TIME AS WELL. TEMPERATURES SHOULD RISE TO THE MID 30S VERY SLOWLY TODAY...BUT OVER THE SNOW COVER...THEY MAY HOLD BETWEEN 30 AND 32 TODAY. TONIGHT...SKIES SHOULD BECOME CLEAR...OR AT LEAST BECOME SCATTERED...AND WITH LIGHT WINDS...WE SHOULD GET VERY COLD. MID TO UPPER TEENS SHOULD BE FOUND OVER ALL BUT THE FAR SOUTH...WHERE NEAR 20 IS LIKELY. OVER THE REMAINING SNOWPACK...LOWS COULD REALLY TUMBLE DOWN. FOR NOW...WILL GO WITH 10 TO 15 IN THESE SPECIFIC LOCATIONS. ...ERVIN... .LONG TERM...FRIDAY THROUGH WEDNESDAY... TEMPERATURES MAIN FOCUS EARLY...THEN POTENTIAL FOR PRECIPITATION EARLY NEXT WEEK. SURFACE HIGH DROPS SE OUT OF NORTHERN PLAINS PASSING TO SOUTH ON FRI WITH NW FLOW ALOFT. LIMITED MIXING AND COLD START WILL LIMIT HIGHS TO MID 30S OVER REMNANTS OF CURRENT SNOW/WET GROUND OVER EAST CENTRAL IA WITH SW CWA POSSIBLY REACHING 40 WITH HELP OF LIGHT SW WINDS BY AFTERNOON. FRI NIGHT SHOULD NOT BE AS COLD WITH INCREASING SW FLOW AHEAD OF SURFACE TROUGH AND UPPER SHORTWAVE THAT PUSHES THROUGH SAT. FORCING AND WEAK MID LEVEL INSTABILITY ASSOCIATED WITH THIS TROUGH THAT IS PROGGED TO PUSH THROUGH SAT AFTERNOON MAY BE ENOUGH TO PRODUCE FLURRIES AND BROUGHT INTO FORECAST KEEPING POPS BELOW SLIGHT CHANCE FOR NOW. TEMPERATURES WILL CONTINUE TO MODERATE OVER WEEKEND WITH HIGHS CLOSER TO LATE NOV CLIMO AVERAGES IN 40S. BEYOND...MODELS STILL DIVERGE ON PATH OF H5 LOW THAT WILL BE OVER TX SUN NIGHT THAT EJECTS NORTHEAST INTO OPEN WAVE EARLY NEXT WEEK. ECMWF CONTINUES TO BE FASTEST SOLUTION WITH MOST NORTHERN PATH...WITH UPPER WAVE AND SURFACE LOW INTO LOWER MI MON NIGHT...WHICH WOULD BE FAVORABLE FOR PRECIPITATION IN AT LEAST SE HALF CWA. GFS AND UKMET...NOT NEARLY AS PROGRESSIVE AND TAKE MORE SOUTHERLY ROUTE WITH THIS FEATURE. WILL HANDLE WITH SLIGHT CHANCE POPS FOR RAIN OR SNOW SUN NIGHT INTO MON UNTIL MODELS GET A BETTER HANDLE AND AGREEMENT ON THIS FEATURE. EXTENDED MODELS DEPICT ACTIVE PATTERN FOR MUCH OF NEXT WEEK. ..SHEETS.. && .AVIATION... MVFR CIGS AROUND 2500FT SHOULD LAST THROUGH THE DAY TODAY AT ALL TAF SITES...BUT FROM TIME TO TIME...THEY WILL GIVE WAY TO A VFR MID CLOUD DECK AROUND 8000FT. VISIBILITIES SHOULD REMAIN ABOVE 6 MILES ALL DAY...THOUGH A FEW SNOW FLURRIES WILL BE POSSIBLE THROUGH 4 PM. TONIGHT...VFR CONDITIONS ARE ANTICIPATED WITH LIGHT WINDS. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ ERVIN/SHEETS ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 735 PM MST FRI NOV 23 2007 .DISCUSSION... BACK EDGE OF PRECIP SHIELD HAS ENTERED THE NORTHWEST 1/4 OF THE AREA WITH LIGHT SNOW AHEAD OF IT. VISIBILITIES REMAIN IN THE ONE TO FOUR MILE RANGE. HAVE STARTED TO CANCEL THE ADVISORY ALONG AND BEHIND THE PRECIP SHIELD AND AS THE NIGHT GOES ON I EXPECT TO CONTINUE CANCELLING IT BEFORE THE 12Z EXPIRATION CURRENTLY IN EFFECT. CALLS TO ALL OF THE LAW ENFORCEMENT AGENCIES AT 23Z SUGGEST SNOW DEPTHS RANGING FROM A HALF INCH TO INCH ACROSS THE SOUTH TO ONE TO TWO INCHES ALONG INTERSTATE 70 TO ONE TO FOUR INCHES (FOUR IN HITCHCOCK COUNTY) IN NEBRASKA. CO-OP REPORTS WILL GIVE A BIT MORE DETAIL AS FAR AS AMOUNTS IN THE MORNING. ADJUSTED TEMP/DP GRIDS WHICH GENERALLY SHOW HIGHER NUMBERS THAN PREVIOUSLY EXPECTED. THIS IS IN LINE WITH THE SREF/NAM/RUC FORECASTS AND MATCHES WELL TO CURRENT REAL DATA. && .AVIATION... FOR 00Z TAFS...PERIODS OF -SN TO SN WILL CONTINUE THROUGH THE EARLY EVENING BEFORE TAPERING OFF FROM WEST TO EAST AT THE TWO TERMINALS AFTER 05Z...SLOWER TO END AT MCK. IFR CIGS AND VIS SHOULD HOLD THROUGH THE NIGHT BEFORE A SLOW MIX OUT IN CIGS STARTING AT 14/15 UTC. CIGS AND VIS SHOULD BECOME MVFR TO VFR TOMORROW AFTERNOON. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR KSZ003-004-014>016-028- 029. NE...NONE. CO...NONE. && $$ DDT/05 ks AREA FORECAST DISCUSSION...CORRECTED TYPO NATIONAL WEATHER SERVICE TOPEKA KS 318 AM CST THU NOV 22 2007 .DISCUSSION... FORECAST LOOKS TO BE IN PRETTY GOOD SHAPE AND HAVE NOT NEEDED TO MAKE MANY CHANGES. 08Z WATER VAPOR IMAGERY SHOWS A BROAD MID LEVEL TROUGH OVER THE NORTH CENTRAL CONUS WITH A SHORTWAVE ROTATING SOUTH THROUGH THE BACKSIDE OF THE TROUGH ACROSS THE NEB PANHANDLE. A COUPLE OTHER SHORTWAVES WERE NOTED OVER THE WEST IN THE BROAD CYCLONIC FLOW. ONE MOVING ACROSS THE DESERT SOUTHWEST AND A SECOND MOVING SOUTH ACROSS THE PACIFIC NORTHWEST. SFC OBS AT 08Z SHOW RIDGE CENTERED ACROSS WESTERN KS AND THE HIGH PLAINS. MAIN CONCERN IN THE FORECAST IS CHANCES FOR SNOW FRIDAY NIGHT. THE 00Z GFS IS THE PREFERRED MODEL WITH THE SUPPORT OF THE CANADIAN... UKMET AND ECMWF. THESE MODELS HANDEL THE SHORTWAVE CURRENTLY DIVING DOWN THE PACIFIC NORTHWEST SIMILARLY...AND EJECT IT OUT ACROSS THE CENTRAL HIGH PLAINS ON FRIDAY NIGHT. WITH SOME WEAK WAA AND ISENTROPIC LIFT...THE GFS ALSO SHOWS SOME Q VECTOR CONVERGENCE MOVING ACROSS THE FORECAST AREA AHEAD OF THE SHORTWAVE. WHILE MOISTURE ADVECTION DOES NOT LOOK ALL THAT GREAT...MODELS DO SATURATE THE LOWER ATMOSPHERE. BECAUSE OF THIS AND THE EXPECTED FORCING...TWEAKED POPS UP A LITTLE...MAINLY ACROSS CENTRAL KS. THERE IS SOME CONCERN THAT THE FORCING WILL FALL APART AS THE SHORTWAVE MOVES EAST AND THE NORTHERN STREAM TROUGH ABSORBS THE SHORTWAVE. IN ANY CASE GIVEN AMOUNT OF MOISTURE TO WORK WITH...EXPECT ANY SNOWFALL TO BE LIGHT WITH AMOUNTS LESS THAN AN INCH. OTHERWISE VERY DRY AIR IN PLACE SHOULD PRECLUDE ANY PRECIP IN THE SHORT TERM. SHORTWAVE MOVING ACROSS WESTERN NEB WILL LIKELY BRING SOME MID LEVEL CLOUDS INTO NORTHER KS THIS AFTERNOON. THERE ARE EVEN SOME RADAR RETURNS SHOWING UP ON KLBF WITHIN THE SC OVER WESTERN NEB. 06Z NAM AND RUC SHOW THIS CLOUD DECK DISSIPATING AS IT MOVES INTO NORTHEAST KS...BUT THE SC COULD HOLD TOGETHER AND MOVE INTO THE CNK AREA. THIS COULD KEEP AFTERNOON HIGHS A COUPLE DEGREES COOLER THAN THEY WOULD OTHERWISE BE. THINK THAT FOR THE MOST PART THERE SHOULD BE SOME DECENT SOLAR INSOLATION FOR THIS TIME OF YEAR TO OFF SET THE WEAKENING CAA. THEREFORE HAVE TEMPS FROM THE MID 30S ACROSS NORTH CENTRAL KS WERE THERE COULD BE MORE CLOUD COVER...TO AROUND 40 OVER EAST CENTRAL KS. FRIDAY MORNING LOWS SHOULD PLUNGE INTO THE TEENS AS THE SFC RIDGE SLIDES BY CAUSING LIGHT WINDS WITH CLEAR SKIES. DID NOT MAKE ANY CHANGES TO THE FORECAST BEYOND SATURDAY. THERE IS STILL UNCERTAINTY WITH THE SYSTEM EJECTING OUT FROM OLD MEXICO ON SUNDAY NIGHT AND MONDAY. THE GFS KEEPS THE SYSTEM SOUTH WHILE THE ECMWF IS FURTHER NORTHWEST WITH THE TRACK OF THE UPPER LOW. && WOLTERS .AVIATION... LOW CLOUDS...1500-2000 FT...WRAPPING SOUTHEAST OVER FAR EASTERN NEBRASKA AND A PERSISTENT BAND OF 3000=5000FT CLOUDS OVER WEST CENTRAL NEBRASKA TRYING TO PUSH INTO PARTS OF NORTHCENTRAL KANSAS AT 08Z. LATEST RUC/NAM12 SOUNDINGS/PLAN VIEW SHOWING INCREASE IN H925-H850MB RH 12Z-18Z THEN DECREASING IN AFTERNOON. AT THIS POINT WILL ADD AT LEAST SOME SCT 2500-3000FT CLOUDS TO GOING TAFS AROUND 15-16Z WITH INCREASE NORTHWEST WINDS IN THE 8 TO 12KT RANGE. EXPECTING GENERALLY CLEAR SKIES AFT 00Z WITH WINDS BECOMING LIGHT AND VARIABLE. && PF .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ HAPPY THANKSGIVING! ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 814 PM EST FRI NOV 23 2007 .SHORT TERM.../THE REST OF TONIGHT/...UPDATED SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA THROUGH TONIGHT...DRYING OUT THE LOWER LEVELS AND VEERING THE SURFACE WINDS TO SOUTHWESTERLY. WITH DRIER AIR MOVING IN...CLOUD COVER WILL CONTINUE TO DIMINISH ALLOWING FOR GOOD RADIATIONAL COOLING AND LOW TEMPERATURES IN THE LOW TO MID 20S OVERNIGHT. FORECAST IS ON TRACK FOR THIS EVENING...SO WILL ONLY MAKE MINOR CHANGES TO GRIDS BASED ON CURRENT OBSERVATIONS. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TONIGHT THROUGH SATURDAY NIGHT/ THE COMBINATION OF A FAIRLY STRONG SHORT WAVE AND A STREAM OF MOISTURE FROM LAKE MICHIGAN MOVED ACROSS THE AREA TODAY BRINGING WITH IT MOSTLY CLOUDY SKIES AND MANY INSTANCES OF SNOW FLURRIES. SOME OF THE FLURRIES GOT A LITTLE STRONGER AND A FEW LIGHT SNOW SHOWERS ALSO DEVELOPED. AS THE SUN SETS TODAY AND THE WINDS START SHIFTING MORE TO THE NORTH...THE CLOUDS SHOULD GO AWAY. WITH THE WINDS SHIFT...DRIER AIR WILL BE MAKING ITS WAY INTO THE AREA. THE COMBINATION OF THE DRIER AIR AND CLEARING SKIES...WILL COMBINE TO PUT A BIT OF FROST ON THE PUMPKIN TONIGHT. TOMORROW WILL BE QUITE PLEASANT WITH HIGHS REBOUNDING TO NEAR 50. THE CLOUDS SHOULD BE STEADILY INCREASING TOMORROW AFTERNOON AS SOME CIRRUS AND HIGH CLOUDS START MOVING INTO THE AREA AHEAD OF THE NEXT FRONT. MADE ONLY SLIGHT TWEAKS TO THE TEMPERATURE FORECAST FROM MID SHIFT. GENERALLY WENT WITH A MOS BLEND. .LONG TERM.../SUNDAY THROUGH FRIDAY/ MOISTURE BEGINS TO INCREASE ON SUNDAY. ISENTROPIC LIFT WITH WARM AIR ADVECTION WILL BRING A CHANCE OF RAIN TO THE AREA...WITH THE HIGHEST CHANCES SOUTH OF THE HAL ROGERS PARKWAY. CLOUDS WILL INCREASE THROUGHOUT THE DAY FROM NORTH TO SOUTH. GENERALLY LIKE THE GFS/ECMWF SOLUTIONS WITH THE HANDLING OF A DEVELOPING LOW PRESSURE SYSTEM OVER THE MISSISSIPPI VALLEY. A NEGATIVELY TILTED H5 TROF WILL DIG INTO THE MISSISSIPPI VALLEY REGION SUNDAY NIGHT...AS A SURFACE LOW STRENGTHENS OVER LOUISIANA AND MISSISSIPPI. THIS LOW...AND ITS ASSOCIATED WARM FRONT...WILL MOVE NORTH SUNDAY NIGHT. THE LOW IS EXPECTED TO REACH WESTERN KENTUCKY BY MONDAY MORNING...WITH THE WARM FRONT REACHING THE OHIO RIVER. THIS WILL SPREAD SHOWERS ACROSS THE AREA THROUGH THE NIGHT. MODELS INDICATE WEAK INSTABILITY WITH THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS...COMBINED WITH SIGNIFICANT SPEED AND DIRECTIONAL SHEAR...COULD LEAD TO A FEW GUSTY THUNDERSTORMS. THE LIMITING FACTOR IN THUNDERSTORM DEVELOPMENT WILL BE THE WEAK INSTABILITY...HOWEVER ANY STORM THAT DEVELOPS COULD BE SEVERE WITH PLENTY OF SHEAR AND STRONG WINDS ALOFT. IN FACT...THE GFS SHOWS A 70KT H8 JET MOVING ACROSS THE REGION LATE SUNDAY NIGHT INTO EARLY MONDAY AFTERNOON. THE WRF IS A LITTLE WEAKER WITH THE JET...BUT STILL SHOWS 60 KT. WENT CATEGORICAL POPS SUNDAY NIGHT INTO MONDAY WITH PLENTY OF MOISTURE AND DYNAMICS MOVING ACROSS THE REGION. EVEN IF THUNDERSTORM DO NOT DEVELOP...THINK ANY OF THE SHOWERS WILL BE ABLE TO MIX DOWN SOME GUSTY WINDS LATE SUNDAY NIGHT AND MONDAY. AN INVERSION IN PLACE MAY HELP TO LIMIT MIXING OF WINDS INITIALLY...BUT LATER MONDAY MORNING THE LOWER LEVELS WARM ENOUGH TO ALLOW FOR NON CONVECTIVE MIXING AS WELL...WHICH COULD ALSO LEAD TO STRONG WIND GUSTS. WILL CONTINUE TO CLOSELY MONITOR THIS SITUATION OVER THE NEXT COUPLE OF DAYS. THE LOW WILL MOVE NORTHEAST DURING THE DAY MONDAY...DRAGGING A COLD FRONT THROUGH THE AREA. THE LOW PRESSURE SYSTEM WILL MOVE NORTHEAST TO THE LOWER GREAT LAKES BY MONDAY NIGHT...HOWEVER SOME WRAP AROUND MOISTURE AND H5 VORT MAX WILL KEEP A CHANCE OF SHOWERS IN THE AREA THROUGH TUESDAY MORNING. H8 TEMPS REACH 0 TO -1 DEG C MONDAY NIGHT...HOWEVER THICKNESS REMAIN ABOVE CRITICAL THRESHOLDS...SO KEPT PRECIPITATION ALL RAIN. HIGH PRESSURE BUILDS INTO THE AREA LATER TUESDAY...BRINGING CLEARING SKIES AND DRY WEATHER. A FAST MOVING COLD FRONT IS EXPECTED TO MOVE EAST ACROSS THE AREA LATE WEDNESDAY NIGHT INTO THURSDAY...BRINGING ANOTHER CHANCE OF SHOWERS TO THE REGION. GOOD COLD AIR ADVECTION BEHIND THE FRONT...BUT WITH HIGH PRESSURE RAPIDLY BUILDING IN AND A LACK OF MOISTURE...WILL NOT INCLUDE A POSSIBILITY OF ANY UPSLOPE SNOW FLURRIES ATTM. MODELS DIFFER ON THE DEVELOPMENT OF A SYSTEM IN THE SOUTHWESTERN CONUS ON FRIDAY. THE ECMWF AND GFS WERE INITIALLY IN SOMEWHAT AGREEMENT ON THIS SYSTEM...HOWEVER THE LATEST MODEL RUNS DIFFER. THE GFS KEEPS THE SYSTEM MUCH LESS DEVELOPED FROM EARLIER RUNS...AND FURTHER SOUTH OF OUR AREA. THE ECMWF TRENDED WEAKER ON ITS LATEST RUN...BUT STILL ALLOWS FOR A CHANCE OF RAIN LATE FRIDAY. PREFER TO SIDE CLOSER TO THE ECMWF/S HANDLING OF THIS SYSTEM...WITH A H5 TROF DIGGING INTO THE WESTERN CONUS. COLDER AIR SHOULD BE MOVING NORTH OF THE REGION BEFORE ANY MOISTURE MOVES IN WITH THIS SYSTEM. UNDERCUT MOS GUIDANCE ON SEVERAL DAYS...WITH GOOD COLD AIR ADVECTION OCCURRING BEHIND THE SERIES OF SYSTEMS MOVING THROUGH. && .AVIATION.../00Z TO 24Z/ CLOUDS ARE SLOWLY DISSIPATING AND EXPECT CLEAR CONDITIONS BY MIDNIGHT. HIGH PRESSURE IS BECOMING MORE DOMINANT AND ALSO SLIDING FARTHER EAST. RUC SHOWS THAT 850 MB FLOW WILL BE DIRECTLY DOWNSLOPE OFF OF THE APPALACHIANS BY 09Z. A 700 MB SHORTWAVE WILL PASS OVER SAT AFTERNOON FOR AN INCREASE IN MID/HIGH CLOUDS BUT LITTLE ELSE. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JJ/SCHOETTMER LONG TERM....WJM AVIATION...GV ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 714 PM EST FRI NOV 23 2007 .SHORT TERM.../TONIGHT THROUGH SATURDAY NIGHT/ THE COMBINATION OF A FAIRLY STRONG SHORT WAVE AND A STREAM OF MOISTURE FROM LAKE MICHIGAN MOVED ACROSS THE AREA TODAY BRINGING WITH IT MOSTLY CLOUDY SKIES AND MANY INSTANCES OF SNOW FLURRIES. SOME OF THE FLURRIES GOT A LITTLE STRONGER AND A FEW LIGHT SNOW SHOWERS ALSO DEVELOPED. AS THE SUN SETS TODAY AND THE WINDS START SHIFTING MORE TO THE NORTH...THE CLOUDS SHOULD GO AWAY. WITH THE WINDS SHIFT...DRIER AIR WILL BE MAKING ITS WAY INTO THE AREA. THE COMBINATION OF THE DRIER AIR AND CLEARING SKIES...WILL COMBINE TO PUT A BIT OF FROST ON THE PUMPKIN TONIGHT. TOMORROW WILL BE QUITE PLEASANT WITH HIGHS REBOUNDING TO NEAR 50. THE CLOUDS SHOULD BE STEADILY INCREASING TOMORROW AFTERNOON AS SOME CIRRUS AND HIGH CLOUDS START MOVING INTO THE AREA AHEAD OF THE NEXT FRONT. MADE ONLY SLIGHT TWEAKS TO THE TEMPERATURE FORECAST FROM MID SHIFT. GENERALLY WENT WITH A MOS BLEND. .LONG TERM.../SUNDAY THROUGH FRIDAY/ MOISTURE BEGINS TO INCREASE ON SUNDAY. ISENTROPIC LIFT WITH WARM AIR ADVECTION WILL BRING A CHANCE OF RAIN TO THE AREA...WITH THE HIGHEST CHANCES SOUTH OF THE HAL ROGERS PARKWAY. CLOUDS WILL INCREASE THROUGHOUT THE DAY FROM NORTH TO SOUTH. GENERALLY LIKE THE GFS/ECMWF SOLUTIONS WITH THE HANDLING OF A DEVELOPING LOW PRESSURE SYSTEM OVER THE MISSISSIPPI VALLEY. A NEGATIVELY TILTED H5 TROF WILL DIG INTO THE MISSISSIPPI VALLEY REGION SUNDAY NIGHT...AS A SURFACE LOW STRENGTHENS OVER LOUISIANA AND MISSISSIPPI. THIS LOW...AND ITS ASSOCIATED WARM FRONT...WILL MOVE NORTH SUNDAY NIGHT. THE LOW IS EXPECTED TO REACH WESTERN KENTUCKY BY MONDAY MORNING...WITH THE WARM FRONT REACHING THE OHIO RIVER. THIS WILL SPREAD SHOWERS ACROSS THE AREA THROUGH THE NIGHT. MODELS INDICATE WEAK INSTABILITY WITH THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS...COMBINED WITH SIGNIFICANT SPEED AND DIRECTIONAL SHEAR...COULD LEAD TO A FEW GUSTY THUNDERSTORMS. THE LIMITING FACTOR IN THUNDERSTORM DEVELOPMENT WILL BE THE WEAK INSTABILITY...HOWEVER ANY STORM THAT DEVELOPS COULD BE SEVERE WITH PLENTY OF SHEAR AND STRONG WINDS ALOFT. IN FACT...THE GFS SHOWS A 70KT H8 JET MOVING ACROSS THE REGION LATE SUNDAY NIGHT INTO EARLY MONDAY AFTERNOON. THE WRF IS A LITTLE WEAKER WITH THE JET...BUT STILL SHOWS 60 KT. WENT CATEGORICAL POPS SUNDAY NIGHT INTO MONDAY WITH PLENTY OF MOISTURE AND DYNAMICS MOVING ACROSS THE REGION. EVEN IF THUNDERSTORM DO NOT DEVELOP...THINK ANY OF THE SHOWERS WILL BE ABLE TO MIX DOWN SOME GUSTY WINDS LATE SUNDAY NIGHT AND MONDAY. AN INVERSION IN PLACE MAY HELP TO LIMIT MIXING OF WINDS INITIALLY...BUT LATER MONDAY MORNING THE LOWER LEVELS WARM ENOUGH TO ALLOW FOR NON CONVECTIVE MIXING AS WELL...WHICH COULD ALSO LEAD TO STRONG WIND GUSTS. WILL CONTINUE TO CLOSELY MONITOR THIS SITUATION OVER THE NEXT COUPLE OF DAYS. THE LOW WILL MOVE NORTHEAST DURING THE DAY MONDAY...DRAGGING A COLD FRONT THROUGH THE AREA. THE LOW PRESSURE SYSTEM WILL MOVE NORTHEAST TO THE LOWER GREAT LAKES BY MONDAY NIGHT...HOWEVER SOME WRAP AROUND MOISTURE AND H5 VORT MAX WILL KEEP A CHANCE OF SHOWERS IN THE AREA THROUGH TUESDAY MORNING. H8 TEMPS REACH 0 TO -1 DEG C MONDAY NIGHT...HOWEVER THICKNESS REMAIN ABOVE CRITICAL THRESHOLDS...SO KEPT PRECIPITATION ALL RAIN. HIGH PRESSURE BUILDS INTO THE AREA LATER TUESDAY...BRINGING CLEARING SKIES AND DRY WEATHER. A FAST MOVING COLD FRONT IS EXPECTED TO MOVE EAST ACROSS THE AREA LATE WEDNESDAY NIGHT INTO THURSDAY...BRINGING ANOTHER CHANCE OF SHOWERS TO THE REGION. GOOD COLD AIR ADVECTION BEHIND THE FRONT...BUT WITH HIGH PRESSURE RAPIDLY BUILDING IN AND A LACK OF MOISTURE...WILL NOT INCLUDE A POSSIBILITY OF ANY UPSLOPE SNOW FLURRIES ATTM. MODELS DIFFER ON THE DEVELOPMENT OF A SYSTEM IN THE SOUTHWESTERN CONUS ON FRIDAY. THE ECMWF AND GFS WERE INITIALLY IN SOMEWHAT AGREEMENT ON THIS SYSTEM...HOWEVER THE LATEST MODEL RUNS DIFFER. THE GFS KEEPS THE SYSTEM MUCH LESS DEVELOPED FROM EARLIER RUNS...AND FURTHER SOUTH OF OUR AREA. THE ECMWF TRENDED WEAKER ON ITS LATEST RUN...BUT STILL ALLOWS FOR A CHANCE OF RAIN LATE FRIDAY. PREFER TO SIDE CLOSER TO THE ECMWF/S HANDLING OF THIS SYSTEM...WITH A H5 TROF DIGGING INTO THE WESTERN CONUS. COLDER AIR SHOULD BE MOVING NORTH OF THE REGION BEFORE ANY MOISTURE MOVES IN WITH THIS SYSTEM. UNDERCUT MOS GUIDANCE ON SEVERAL DAYS...WITH GOOD COLD AIR ADVECTION OCCURRING BEHIND THE SERIES OF SYSTEMS MOVING THROUGH. && .AVIATION.../00Z TO 24Z/...UPDATED CLOUDS ARE SLOWLY DISSIPATING AND EXPECT CLEAR CONDITIONS BY MIDNIGHT. HIGH PRESSURE IS BECOMING MORE DOMINANT AND ALSO SLIDING FARTHER EAST. RUC SHOWS THAT 850 MB FLOW WILL BE DIRECTLY DOWNSLOPE OFF OF THE APPALACHIANS BY 09Z. A 700 MB SHORTWAVE WILL PASS OVER SAT AFTERNOON FOR AN INCREASE IN MID/HIGH CLOUDS BUT LITTLE ELSE. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JJ LONG TERM....WJM AVIATION...GV FIRE WEATHER...JJ ky AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1025 PM EST FRI NOV 23 2007 .UPDATE... MAIN FCST CONCERNS ARE -SN AND POTENTIAL LES OVER THE KEWEENAW. A SHORTWAVE TROUGH FROM NRN ONTARIO INTO NW MN SUPPORTED AN AREA OF LIGHT SNOW OR FLURRIES OVER NE MN INTO FAR NW WI WITH LOWEST VSBYS GENERALLY IN THE 3-5SM RANGE. S TO SW SFC WINDS PREVAILED ACROSS MOST OF THE CWA AHEAD OF A WEAK TROF MOVING THROUGH NE MN. WITH ADDITIONAL PRES FALLS EXPECTED N OF LAKE SUPERIOR TOWARD DAYBREAK AHEAD OF ANOTHER LOW PRES MOVING SE FROM MANITOBA...AND DEVELOPING LAND BREEZES...MAIN CONVERGENT ZONE OVER WRN LAKE SUPERIOR IS EXPECTED TO REMAIN MAINLY OFFSHORE INTO SAT MORNING. SO...POPS WERE LOWERED OVER THE NRN KEWEENAW. OTHERWISE...280K-285 ISENTROPIC ASCENT AHEAD OF THE SHORTWAVE MAY BRING SOME LIGHT SNOW INTO UPPER MI. HOWEVER...WITH A SIGNIFICANT 850-700 DRY LAYER...PER 03Z KSAW TAMDAR SOUNDING...ONLY WEAK LIFT AND LIMITED MOISTURE AVAILABLE...MAINLY FLURRIES ARE EXPECTED WITH LITTLE OR NO ACCUMULATION. && .SHORT TERM (TONIGHT AND SAT)... MAIN FCST ISSUE REVOLVES AROUND LES. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE ALONG THE W COAST OF NAMERICA WITH THE DOWNSTREAM TROF DOMINATING MUCH OF CNTRL/ERN NAMERICA. IN THE NW FLOW...ONE SHORTWAVE IS OVER NRN ONTARIO WITH A STRONGER SHORTWAVE DROPPING TOWARD NRN SASKATCHEWAN/MANITOBA. WAA REGIME IN RESPONSE TO THE ONTARIO SHORTWAVE HAS BROUGHT A BAND OF MID CLOUDS AND STRATOCU INTO UPPER MI TODAY. SOME FLURRIES HAVE ALSO OCCURRED OVER THE WRN FCST AREA. MEANWHILE...THE LOW-LEVEL SW FLOW THAT HAS DEVELOPED HAS SHIFTED WHAT IS LEFT OF LES COMPLETELY OFFSHORE OF UPPER MI. EARLIER TODAY...THERE WAS A DOMINANT BAND CLOSE TO THE N SHORE OF MN EXTENDING NE TO JUST N OF ISLE ROYALE. IT APPEARS MUCH OF THAT BAND HAS BROKEN UP. IT`S DIFFICULT TO TELL WHAT IS HAPPENING NOW AS HIGHER CLOUDS ARE OBSCURING LAKE EFFECT...BUT THERE ARE SOME HINTS THAT LES IS OCCURRING BTWN THE KEWEENAW AND ISLE ROYALE. WITH 850MB TEMPS RISING NO HIGHER THAN -9C TONIGHT...LES WILL CONTINUE TO BE A POSSIBILITY...AND ONGOING SW FLOW WILL ALLOW FOR THE POTENTIAL OF LONG FETCH SW-NE ORIENTED LES BANDS OVER WRN LAKE SUPERIOR. AS SHORTWAVE OVER NRN ONTARIO HEADS ESE...SFC TROF NOW EXTENDING FROM NRN ONTARIO TO FAR NW MN WILL SLIP OVER LAKE SUPERIOR TONIGHT. THIS WILL ENHANCE THE CONVERGENCE...PROMOTING THE DEVELOPMENT OF A DOMINANT BAND ALONG THE TROF. ALL THE MODELS SUGGEST THIS...BUT THE RUC13 AND LOCALLY RUN HIGH RES WRF-ARW ARE MUCH MORE WELL-DEFINED WITH THE BAND. SO THE QUESTION IS...WILL THE WINDS BECOME WRLY ENOUGH TO PUSH THIS BAND TO THE KEWEENAW. CURRENTLY...PRES RISES BEHIND THE SFC TROF ARE WEAKENING TO THE POINT THAT THERE ARE ALMOST NO RISES NOTED IN THE LAST 3HRS...AND PRES FALLS ARE ALREADY INCREASING AND SPREADING S INTO SCNTRL CANADA AHEAD OF THE STRONGER SHORTWAVE DROPPING S IN NRN CANADA. THUS...IT WOULD APPEAR THE TROF/WIND SHIFT WILL NOT MAKE SIGNIFICANT PROGRESS ACROSS THE LAKE. HOWEVER...WITH SOME UNCERTAINTY...WILL KEEP CHC POPS N OF HOUGHTON OVERNIGHT AND JUST BRUSH THE SHORE OF KEWEENAW COUNTY WITH LIKELY POPS AND ABOUT 1 INCH OF ACCUMULATION. EVENING SHIFT WILL PROBABLY BE ABLE TO SHIFT HIGHER POPS OFFSHORE OF THE KEWEENAW IF UPSTREAM PRES FALLS BECOME MORE SIGNIFICANT BEHIND TROF. AS FOR LES NEAR LAKE MICHIGAN...SW FLOW WILL HAVE ENOUGH WRLY COMPONENT TO KEEP ANY LES OFF LAKE MICHIGAN E OF THE FCST AREA. AWAY FROM THE POSSIBLE LES OVER THE KEWEENAW...MAINTAINED A MENTION OF SLIGHT CHC -SHSN OVERNIGHT ACROSS THE FCST AREA AS SFC OBS/RADAR INDICATE SOME -SN/FLURRIES IN THE VCNTY OF SFC TROF. SHORTWAVE CURRENTLY DROPPING TOWARD SASKATCHEWAN/MANITOBA WILL REACH NRN ONTARIO SAT. AS A RESULT...WIND DIRECTION WILL CHANGE LITTLE FOR MOST OF SAT. SO...THE TIP OF THE KEWEENAW REMAINS THE ONLY LOCATION FOR ANY LES CONCERNS. SINCE THERE IS A HINT THAT THE 850MB WINDS TAKE ON A MORE WRLY DIRECTION SAT AFTN...THE POTENTIAL FOR LES ON THE KEWEENAW SHOULD IMPROVE DURING THE DAY. IF LES DOES NOT REACH THAT AREA TONIGHT...IT SHOULD SAT AFTN. GIVEN THE UNCERTAINTY...KEPT SNOW AMOUNTS CONSERVATIVE WITH JUST 1 TO MAYBE 3 INCHES NORTH OF HOUGHTON. LONGER TERM...00Z SUN ONWARD... NAM SHOWING 500 MB FLOW GETTING ZONAL ON SUN AFTER TROUGH AXIS PASSES THROUGH EARLY SAT NIGHT WITH TROUGHING FOR MON. THERE IS A NARROW RIBBON OF MOISTURE ON THE I280K-I295K SURFACES ON THE NAM ACROSS SOUTHERN AND CENTRAL LAKE SUPERIOR SAT NIGHT THAT SHIFTS TO THE NORTH ON SUN. GFS SHOWS THIS AS WELL ON I280K-I300K SURFACES ALONG WITH BOTH MODELS SHOWING SOME WEAK 850-500 MB Q-VECTOR CONVERGENCE WHICH REMAINS ON SUN ACROSS THE CWA. WITH WEST WINDS ON SAT NIGHT THROUGH SUN MORNING...THE KEWEENAW COULD SEE SOME DECENT SNOW WITH A POSSIBLE SEEDER FEEDER MECHANISM SETTING UP TO HELP THE SNOWFALL RATES ALONG. GFS SOUNDINGS FOR KCMX AND KP59 SHOW INVERSION HEIGHTS ABOUT 5000 FEET THEN AND THIS FALLS LATE SAT NIGHT INTO SUN MORNING. PROBLEM LATE SAT NIGHT INTO SUN MORNING IS THERE IS WARMING AT 850 MB FROM -8C TO -10C TO -6C TO -8C BY 12Z SUN AND THEN 850 MB TEMPERATURES WARM MORE AFTER THAT AND THE WIND TURNS SOUTHERLY BY 18Z SUN. LAKE EFFECT COMBINED WITH THE NARROW RIBBON OF MOISTURE IN THE LOW AND MID LEVELS WILL GIVE SNOWFALL AMOUNTS UP TO 6 INCHES SAT NIGHT INTO SUN MORNING OVER THE KEWEENAW WITH THE RIBBON OF MOISTURE CONFINED TO THE NORTHERN CWA AT THAT TIME AND THIS WILL STILL NEED TO BE WATCHED AS THIS COULD BE ADVISORY AMOUNT SNOW OR JUST BELOW ADVISORY DEPENDING ON HOW AND WHERE THE LAKE EFFECT SNOWBAND SETS UP AND IF IT MOVES BACK AND FORTH AT ALL. THIS IS THE ONLY SPOT THAT WOULD SEE SIGNIFICANT SNOW WITH THE LAKE EFFECT COMBINED WITH THE NARROW RIBBON OF MOISTURE. WILL GO UNDERNEATH ADVISORY AMOUNTS FOR NOW AS GFS SOUNDINGS SHOW THE LOWEST LEVELS AGAIN HAVE AN INVERTED-V SOUNDING LOOK TO THEM WITH SOME DRY AIR AND THIS SHOULD CUT INTO AMOUNTS A BIT. OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST EXCEPT TO GO LIKELY OVER THE KEWEENAW PENINSULA WITH THE LAKE EFFECT SNOW BAND AND THE SYNOPTIC MOISTURE AROUND. FOR TEMPERATURES...DID NOT MAKE ANY CHANGES OR VERY LITTLE CHANGE TO THE GOING FORECAST. IN THE EXTENDED...GFS...ECMWF AND CANADIAN MODELS ALL SHOW THE 500 MB PATTERN CONSISTS OF A TROUGH MOVING INTO THE UPPER GREAT LAKES 00Z TUE WITH A SHORTWAVE RIDGE AFFECTING THE AREA 00Z WED. ANOTHER TROUGH MOVES IN FOR 00Z THU AND FOR 00Z FRI WITH RIDGING FOR 00Z SAT. WE END UP GETTING TWO STORMS WITH THE FIRST ON MON AND THE NEXT ON WED AND THU. THE ONE FOR WED AND THU COULD BE A SIGNIFICANT SNOW PRODUCER BEHIND IT WITH LAKE EFFECT SNOW AND STRONG NORTH TO NORTHWEST WINDS. WILL HAVE TO WATCH THIS ONE WITH ITS TRACK ANYWAY. WENT CLOSE TO 06Z GFS AND 00Z ECMWF FOR THIS FORECAST. TEMPERATURES LOOK TO BE COLDER THAN NORMAL IN THE EXTENDED STARTING ON WED AND WENT CLOSE TO ADJMXR FOR LOWS AND HIGHS. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL AT KSAW THRU THIS FCST PERIOD. THERE MIGHT BE A FEW FLURRIES LATE IN THE NIGHT AND SAT MORNING...BUT NO VIS RESTRICTION IS EXPECTED. AT KCMX...VFR CONDITIONS WILL PREVAIL WHILE AWAITING THE EVOLUTION OF LAKE EFFECT -SHSN OVER WRN LAKE SUPERIOR. IT REMAINS VERY UNCERTAIN WHETHER THE WINDS WILL VEER WRLY ENOUGH LATE TONIGHT OR SAT MORNING TO BRING WHAT COULD BE A FAIRLY SIGNIFICANT DOMINANT SNOW BAND ONSHORE AS FAR S AS KCMX. WITH LOW CONFIDENCE...TENTATIVELY INCLUDED MVFR VIS IN -SHSN MID MORNING SAT BASED ON SUGGESTION FROM SOME OF THE HIGHER RESOLUTION FORECAST MODELS THAT WINDS WILL VEER ENOUGH TO THE W. CONDITIONS COULD REMAIN VFR OR DROP TO IFR DEPENDING ON VERY SUBTLE CHANGES IN WIND DIRECTION. WHETHER OR NOT SNOW DEVELOPS...WINDS WILL LIKELY BECOME RATHER GUSTY IN THE AFTERNOON. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FCST CONCERN CONTINUES TO BE THE POTENTIAL OF GALES SAT/SAT NIGHT. LATEST ROUND OF FCST GUIDANCE SUPPORTS THE THINKING OF THE LAST COUPLE OF DAYS THAT WSW GALES WILL IN FACT OCCUR SAT AFTN/EVENING AS PRES GRADIENT TIGHTENS AHEAD OF A LOW PRES TROF DROPPING SE TOWARD LAKE SUPERIOR. HAVE THUS ISSUED GALE WARNINGS FOR THE OPEN WATERS OF LAKE SUPERIOR SAT AFTN/NIGHT. BEFORE THE GALES BEGIN...STIFF SW WINDS OF 20-30KT WILL DOMINATE TONIGHT/SAT MORNING WITH THE STRONGEST WINDS PROBABLY BTWN THE KEWEENAW AND ISLE ROYALE. ANOTHER ROUND OF GALES...THIS TIME N TO NW GALES...MAY OCCUR LATE WED AS DEEPENING LOW PRES MOVES NE INTO THE GREAT LAKES REGION. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING 1 PM SAT TO MIDNIGHT EST SAT NIGHT LSZ263-264. GALE WARNING 4 PM SAT TO 3 AM EST SUN LSZ265>267. && $$ UPDATE...JLB SHORT TERM...ROLFSON LONG TERM...GJM AVIATION...ROLFSON/TAG MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 948 PM EST FRI NOV 23 2007 .UPDATE...LAKE EFFECT SNOW (LES) EXPERIENCED A LULL IN THE LATE AFTERNOON/EARLY EVENING. SINCE THEN...A DOMINANT BAND HAS TRIED TO REORGANIZE...FROM CROSS VILLAGE TO BOIS BLANC ISLAND...AND IS VERY SLOWLY DRIFTING SOUTHWARD. THIS IS NORTH OF WHERE THE HEAVIER SNOW FELL DURING THE DAY. THIS BAND IS NOT YET ESPECIALLY IMPRESSIVE...AS SYNOPTIC-SCALE MOISTURE AND FORCING IS LACKING. HOWEVER...THERE IS A FAIRLY IMPRESSIVE AREA OF SURFACE CONVERGENCE THAT HAS DEVELOPED OVER THE TIP OF THE MITT...WITH MAINLY SOUTH WINDS OVER NORTHERN LOWER MI...AND WSW WINDS ON BEAVER ISLAND AND THE NORTHERN LK HURON BUOY. FOR THE OVERNIGHT...WILL BE INTERESTING TO SEE IF THE CONVERGENCE ZONE CAN HOLD TOGETHER AS THE PRESSURE GRADIENT TIGHTENS...AHEAD OF THE MAIN COLD FRONT HEADING TOWARD THE CANADIAN PRAIRIE. IF IT CAN...1000-850MB CONVERGENCE WILL STRENGTHEN...AND SO SHOULD THE LES BAND. MIXED SIGNAL FROM THE SHORT-TERM MODELS. THE RUC STRENGTHENS LOW-LEVEL CONVERGENCE WITH TIME...BUT MAINLY BECAUSE ITS SURFACE WIND FIELDS ARE TOO WEAK IN THE HERE AND NOW (ESPECIALLY OVER LAKE MI). THE NAM IS INCLINED TO WEAKEN CONVERGENCE WITH TIME...BUT IT IS ALSO STRUGGLING WITH THE SURFACE WIND FIELDS...WHICH ARE NOT BACKED ENOUGH OVER LAND. AM INCLINED TO THINK THAT SURFACE WINDS WILL REMAIN RELATIVELY BACKED OVER LAND AREAS THRU THE NIGHT. OUTSIDE OF MAIN LES AREAS...CLOUD COVER IS PATCHY/THIN AND HAS HELPED IN KEEPING THE LOW LEVEL WINDS FROM FULLY COUPLING. WITH THAT THOUGHT IN MIND...LES BAND SHOULD STRENGTHEN...THOUGH IT WILL ALSO CONTINUE TO WOBBLE A BIT AS 1000-850MB WINDS SHIFT (SLIGHT BACKING THIS EVENING...SLIGHT VEERING OVERNIGHT...AT LEAST IF THE NAM IS TO BE BELIEVED). OVERALL...HAVE DIMINISHED THE HIGHEST SNOWFALL AMOUNTS IN EMMET COUNTY A BUT...WITH AROUND 4 INCHES OR SO IN THE NORTH HALF OF THE COUNTY. HAVE INCREASED SNOW AMOUNTS DOWNSTREAM...IN FAR NORTHERN CHEBOYGAN COUNTY...AND OUT TOWARD DE TOUR/DRUMMOND. THESE CHANGES WILL PROMPT AN LES ADVISORY FOR NORTHERN CHEBOYGAN CO...WHICH WILL RUN THRU 7 PM SATURDAY. SPEAKING OF WHICH...WILL BUMP UP SNOW AMOUNTS A BIT FOR SATURDAY. SURFACE TEMPS WILL BE ON THE WARM SIDE (AT LEAST INITIALLY). BUT AS THE BETTER FORCING ARRIVES AT MIDDAY (STILL COINCIDENT WITH DELTA T/S AROUND 17C)...BANDED LES OFF THE LAKE SHOULD BE SUFFICIENTLY STRONG TO LOWER SURFACE TEMPS BACK TO AROUND FREEZING. ELSEWHERE IN THE REGION...HAVE ALREADY LOWERED MIN TEMPS A BIT IN SOME SPOTS (LIKE GRAYLING). HOWEVER...WITH WINDS INCREASING WITH TIME...SUSPECT MOST PLACES ARE NEAR (OR HAVE ALREADY SEEN) THEIR LOWS FOR THE NIGHT. ZOLTOWSKI && .AVIATION...ISSUED 625 PM FRI NOV 23... LAKE EFFECT SNOW HAS BEEN WANING IN THE PLN AREA LATE TODAY. THIS RELATIVE LULL SHOULD CONTINUE THRU MOST OF THE EVENING. AN UPTICK IS EXPECTED OVERNIGHT...AS MID LEVEL MOISTURE (8-10K CLOUD DECK OVER NORTHERN WI) MOVES OVERHEAD. THE PERSISTENT SW WINDS WILL HELP RETURN OCCASIONAL IFR CONDITIONS TO PLN LATE TONIGHT...WITH WEAKER SNOW SHOWERS IN THE VICINITY OF TVC...AND LITTLE AT APN. THE MAIN SHOW WILL OCCUR DURING THE DAYLIGHT HOURS ON SATURDAY...AS AN UPPER LEVEL DISTURBANCE BRINGS MUCH DEEPER MOISTURE TO THE REGION. LOW LEVEL WINDS REMAIN SW...RESULTING IN PREVAILING LIFR CONDITIONS AT PLN IN FALLING AND BLOWING SNOW...IFR AT TIMES AT TVC...AND LOW-END MVFR LATE IN THE DAY AT APN. JZ && .PREVIOUS DISCUSSION...ISSUED 404 PM FRI NOV 23... PRIMARY FORECAST CHALLENGE OVER THE NEXT 24 HOURS REMAINS LAKE EFFECT/ENHANCED SNOWFALL AND AMOUNTS...AND WHAT/IF ANY HEADLINES MAY BE NEEDED. EARLY AFTERNOON ANALYSIS PLACES MUCH OF NORTHERN MICHIGAN ON THE BACKSIDE OF LOW LEVEL RIDGE AXIS EXTENDING FROM THE MID MISS VALLEY UP THROUGH EASTERN ONTARIO...WHILE ALOFT...WEAK SHORTWAVE RIDGING BUILDING ACROSS THE REGION IN ADVANCE SHORTWAVE ENERGY DROPPING THROUGH THE NORTHERN HIGH PLAINS. OVERALL LOW LEVEL FLOW REGIME HAS BEEN IN TRANSIT THROUGH THE DAY...STARTING NORTH/NORTHWEST AND ENDING UP MORE WEST/SOUTHWEST AS OF 19Z...WITH A CORRESPONDING SHIFT IN LAKE EFFECT SNOW SHOWERS TOWARD THE WSW FAVORED LOCATIONS. DESPITE RATHER SCANT 900-700MB MOISTURE INITIALLY...LATEST RUC/SATELLITE ANALYSIS SHOWS AN UPTICK IN BOUNDARY LAYER RH GIVEN INCREASINGLY LONG FETCH ACROSS LAKE MICHIGAN. SNOWFALL AMOUNTS THROUGH THE DAY HAVE BEEN RATHER IMPRESSIVE IN A FEW SPOTS...NAMELY OWING TO PRONOUNCED STUBBORN LOW LEVEL CONVERGENCE AS A WEAK WARM FRONT SNUCK ITS WAY NORTH THROUGH THE DAY. BIGGEST WINNERS SO FAR - CHARLEVOIX AND EMMET COUNTIES...WHERE SEVERAL REPORTS OF 3 TO AS MUCH AS LOCALLY 5 INCHES HAVE BEEN NOTED...VERY MUCH IN LINE WITH LATEST KAPX RADAR STORM TOTAL SNOW GRAPHICS. FOR TONIGHT...OVERALL PATTERN PROGGED TO CHANGE VERY LITTLE AS PERSISTENT WEST TO SOUTHWESTERLY FLOW REMAINS INTACT AHEAD OF APPROACHING LOW/MID LEVEL TROUGH. PLENTY OF OVER-LAKE INSTABILITY TO WORK WITH (OBVIOUSLY GIVEN ONGOING SNOWS)...WITH H85 TEMPS PROGGED TO "WARM" JUST SLIGHTLY TO AROUND -10C BY 12Z TOMORROW. 900-700MB RH ALSO QUITE CONDUCIVE FOR LES...WITH VALUES ON THE RISE TO 80 PERCENT OR BETTER OVERNIGHT PER CONTINUED LONG FETCH UP LAKE MICHIGAN. DIFFICULT TO FIND ANY REASON WHY SNOWS WON/T CONTINUE THROUGH MUCH OF THE NIGHT AS WEST/SOUTHWEST FLOW HOLDS STATUS QUO...AND INCREASING GRADIENT ACTS TO PREVENT ANY LAND BREEZES THAT COULD POTENTIALLY TRY TO SHOVE ANY SNOW BANDS FARTHER OFFSHORE. USING THE 15Z SREF POP MEAN AS GUIDANCE...WILL HANG THE HIGHEST POPS ACROSS EMMET AND SOUTHERN MACKINAC COUNTIES (I.E. W/SW FLOW AREAS)...AND WILL RUN WITH A WARNING ACROSS EMMET (GIVEN ALREADY SNOWY CONDITIONS THIS AFTERNOON) AND AN ADVISORY FOR MACKINAC (WITH A HIGHER CRITERIA FOR WARNING). HEADING INTO TOMORROW...UPPER WAVE PROGGED TO SWING THROUGH THE REGION BETWEEN 15Z AND 21Z...WITH AXIS OF DECENT 700-500MB -DIVQ AND MUCH DEEPER PLUME OF MOISTURE (1000-500MB RH INCREASES TO BETTER THAN 90 PERCENT) ANNOUNCING THE LIKELIHOOD OF A SYNOPTIC COMPONENT TO THE EVENT. CONTINUED WEST/SOUTHWEST LOW LEVEL FLOW REGIME SHOULD EASILY CONTRIBUTE TO ENHANCEMENT ACROSS THE STRAITS REGION...HOWEVER WILL BE DEALING WITH SOME POSSIBLE PTYPE ISSUES ALONG THE IMMEDIATE COAST GIVEN LONG PERIOD OF ONSHORE FLOW...WITH FORECAST RAOBS INDICATING FREEZING LEVELS ABOUT 1500 FT AGL. SOME QUESTION WHETHER THIS WILL BE SUFFICIENT FOR MELTING...AND PROBABLY DEPENDENT ON INTENSITY OF PRECIP. HOWEVER...FOR SIMPLICITY...WILL HOLD PRECIP ALL SNOW. OUTSIDE OF THE LAKE ENHANCEMENT...OVERALL INCREASING SYNOPTIC SUPPORT SHOULD BE SUFFICIENT TO GENERATE SOME LIGHT SNOW FROM WEST TO EAST AS -DIVQ AXIS ADVANCES ACROSS NORTHERN MICHIGAN...BUT DOUBTFUL OF MUCH IN THE WAY OF ACCUMULATION GIVEN EXPECTED HIGHS IN THE LOWER/MIDDLE 30S UNDER INCREASING LOW LEVEL WARM ADVECTION AND OVERALL WEAK FORCING. ON THE MARINE SIDE...INCREASINGLY GUSTY WINDS AND BUILDING WAVES EXPECTED ON THE LAKE MICHIGAN SIDE LATE TONIGHT AND ESPECIALLY TOMORROW MORNING AS GRADIENT TIGHTENS...WITH WINDS AT THE TOP OF THE INSTABILITY-MIXED LAYER RUNNING ABOUT 35-40 KNOTS. COUPLED WITH COASTAL CONVERGENCE SHOULD EASILY SEE GUSTS IN THE GALE RANGE...WITH GALE CONDITIONS SPREADING TO OTHER NEARSHORE AREAS BY EARLY AFTERNOON AS CORE OF STRONGER 900-850MB WINDS SPREADS EAST. LAWRENCE SATURDAY NIGHT INTO SUNDAY...SOUTHWEST FLOW LAKE EFFECT IS EXPECTED TO WIND DOWN SATURDAY NIGHT AS THE SHORTWAVE TROUGH MOVES EAST OF THE REGION. 850-700MB RH FALLS FROM 55-65 PCT AT 00Z SUN TO 45-55 PCT BY 12Z AND INVERSION HEIGHTS LOWER FROM AROUND 6KFT TO ABOUT 3KFT OVER THAT SAME TIME PERIOD. THIS ALL POINTS TO A DIMINISHING TREND OF LES ACTIVITY WITH MOST ACCUMULATIONS ARRIVING DURING THE EVENING AND WILL GO UP TO A HALF INCH OVER SOUTHERN MACKINAC AND NORTHERN EMMET COUNTIES. MID-LEVEL DRY AIR WILL CONTINUE TO POUR INTO THE AREA ON SUNDAY AS 850MB TEMPS MODERATE BETWEEN -3C TO -6C IN THE MORNING TO NEAR 0C BY EARLY IN THE EVENING. BELIEVE ANY LINGERING LOW LEVEL INSTABILITY WILL BE TOO SHALLOW FOR ANY LES ACTIVITY AND WILL KEEP SNOW CHANCES OUT OF THE FORECAST. MOISTURE ALONG THE LOW LEVEL BAROCLINIC ZONE WILL MOVE NE INTO ONTARIO AS WILL MID-UPPER LEVEL MOISTURE ALONG THE SOUTHERN FRINGES OF THE JET STREAM. SO WITH THE DEPARTING MOISTURE ACROSS THE NORTHERN CWA...LOOKS LIKE SOME SUNSHINE WILL BE HAD ON SUNDAY WITH HIGHS RANGING FROM THE UPPER 30S NORTH TO MID 40S SOUTH. SUNDAY NIGHT INTO MONDAY...SURFACE LOW PRESSURE AHEAD OF A MID- LEVEL WAVE OVER THE NORTHERN PLAINS WILL TRACK ALONG ITS WARM FRONT ACROSS SOUTHERN ONTARIO. AHEAD OF THE SURFACE LOW...SW WINDS WILL BRING RELATIVELY WARM AIR (850MB TEMPS BETWEEN -3C AND 0C) INTO MICHIGAN...WHICH WILL LEAD TO LOWS IN THE UPPER 20S TO MIDDLE 30S. DRY AIR OVER THE AREA SUNDAY NIGHT WILL EVENTUALLY LOSE OUT TO INCREASING MOISTURE AHEAD OF A NE MOVING SURFACE LOW OUT OF THE SOUTHERN PLAINS...WHICH GETS PICKED UP BY THE AFOREMENTIONED PACIFIC WAVE. THIS LOW WILL TRAVEL INTO THE LOWER OHIO RIVER VALLEY BY MIDDAY TO CENTRAL OHIO BY 00Z TUE. NORTHERN PERIPHERY OF THE DEFORMATION ZONE ON THE NW SIDE OF THE LOW STILL LOOKS TO CLIP COUNTIES NEAR SAGINAW BAY. STILL HARD TO SAY IF PRECIP WILL MAKE HERE SINCE INITIAL DRY AIRMASS WILL NEED TO BE OVERCOME. WILL TAKE OUT PRECIP CHANCES FOR THE MORNING DUE TO THIS REASON BUT WILL LEAVE A LOW CHANCE OF RAIN FOR THE AFTERNOON GIVEN 850MB TEMPS AROUND 0C AND SURFACE TEMPS AROUND 40F. PASSAGE OF AN 850MB TROUGH DURING THE AFTERNOON WILL HELP SWITCH THE WINDS TO THE NW AND ADVECT IN COOLER AIR...BUT NOT COOL ENOUGH FOR LAKE EFFECT PRECIP TO BE GENERATED. HIGHS WILL BE IN THE UPPER 30S TO LOW 40S. TUESDAY THROUGH FRIDAY...MODELS HAVE A LITTLE BETTER HANDLE ON THE NEXT SW LOW DUE TO PASS ACROSS THE OHIO VALLEY ON MONDAY AND INTO THE EASTERN GREAT LAKES ON TUESDAY...BUT STILL HAVE THEIR DIFFERENCES...SPECIFICALLY WITH THE SPEED OF THE SYSTEM. BEYOND TUESDAY...LOW CONFIDENCE EXISTS WITH LOW PRESSURE DEVELOPMENT MID TO LATE NEXT WEEK. PUT HIGHER FAITH IN THE ENSEMBLES THAN ANY ONE PARTICULAR MODEL RUN. TUESDAY...LOW PRESSURE WILL MOVE FROM THE OHIO RIVER VALLEY NE INTO NEW ENGLAND. THE 06Z GFS IS ON THE NORTHERN EDGE OF ENSEMBLE MEMBERS WHILE THE 00Z ECMWF IS ON THE QUICKER SIDE...SO TRIED TO TAKE A MORE CONSENSUS TRACK. THIS WOULD PLACE THE SOUTHEAST CWA ON THE EDGE OF THE DEFORMATION ZONE MONDAY NIGHT. AN INVERTED TROUGH WILL EMANATE FROM THIS LOW AND MOVE ACROSS THE CWA AS THE SURFACE LOW PASSES TO OUR SE. WINDS BEHIND THIS TROUGH WILL SWITCH TO THE NW AND BRING IN COLDER AIR WHICH HAS THE CHANCE TO START UP LAKE EFFECT PROCESSES. 06Z GFS IS ON THE COLDER EDGE OF GUIDANCE AND WILL TEMPER EXPECTATIONS ON HOW QUICK THE COLDER AIR MOVES IN...ESPECIALLY SINCE 00Z GFS ENSEMBLE HAS SLOWED THE PROGRESSION OF THE COLDER AIR INTO THE AREA. BUT WITH THE GENERAL LOW LEVEL CYCLONIC FLOW...AND QUESTION MARKS WITH LAKE EFFECT PROCESSES...WILL LEAVE A GENERAL LOW CHANCE POP MONDAY NIGHT. MEANWHILE...NORTHERN STREAM ENERGY ROTATING AROUND THE POLAR VORTEX WILL SKIRT BY TO THE NORTH WITHOUT MUCH IMPACT. ALTHOUGH THE CORE OF THE COLD AIR WILL SKIRT BY TO THE NORTH...COLD AIR ADVECTION WILL CONTINUE DURING THE DAY AS 850MB TEMPS FALL INTO THE LOWER TEENS. HOWEVER...VERY DRY AIR WILL POUR INTO THE NORTHERN GREAT LAKES BEHIND THE SURFACE LOW...AND DO NOT EXPECT A LARGE LAKE EFFECT EVENT. HIGHS WILL BE IN THE MIDDLE TO UPPER 30S. WEDNESDAY...HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE STATE. ANY LIGHT LAKE EFFECT WILL CONTINUE INTO TUESDAY NIGHT...WHILE MID-HIGH CLOUDS WILL STREAM ACROSS THE AREA WITH SW ALOFT. DRY LOW LEVELS WITH THE SURFACE RIDGE AXIS PRESENT WILL TRY TO KEEP THE AREA PRECIP FREE DESPITE 850MB TEMPS AROUND -10C. SO WILL GO WITH A DRY BUT MOSTLY CLOUDY DAY WITH HIGHS IN THE LOWER TO MIDDLE 30S. THURSDAY THROUGH FRIDAY...CONFIDENCE LOW DURING THIS PERIOD...ALL STEMMING FROM THE STRENGTH OF SURFACE LOW AS THE NEXT PACIFIC WAVE EMERGES FROM THE ROCKIES. 06Z GFS/00Z ECMWF LEAVE THE DOOR OPEN FOR A STRONGER SURFACE WAVE THAT WOULD PASS ACROSS THE CENTRAL GREAT LAKES WEDNESDAY NIGHT...BUT THEIR SOLUTIONS DO NOT HAVE MUCH SUPPORT FROM THE GFS ENSEMBLE MEMBERS. WILL INCREASE POPS HEADING INTO THURSDAY AS SOME SORT OF SURFACE FEATURE PASSES TO THE SOUTH...THEN KEEP A CHANCE OF SNOW FOR FRIDAY FOR THE LAKE EFFECT SNOW BELTS AS COLDER AIR WRAPS IN BEHIND ANY SYSTEM. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST SATURDAY FOR MIZ015-017. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SATURDAY FOR MIZ016. LM...GALE WARNING FROM 7 AM SATURDAY TO 11 AM EST SUNDAY FOR LMZ323- 341-342-344>346. LH...GALE WARNING FROM 7 AM SATURDAY TO 11 AM EST SUNDAY FOR LHZ345>349. LS...GALE WARNING FROM 7 AM SATURDAY TO 5 AM EST SUNDAY FOR LSZ321- 322. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 625 PM EST FRI NOV 23 2007 .AVIATION...LAKE EFFECT SNOW HAS BEEN WANING IN THE PLN AREA LATE TODAY. THIS RELATIVE LULL SHOULD CONTINUE THRU MOST OF THE EVENING. AN UPTICK IS EXPECTED OVERNIGHT...AS MID LEVEL MOISTURE (8-10K CLOUD DECK OVER NORTHERN WI) MOVES OVERHEAD. THE PERSISTENT SW WINDS WILL HELP RETURN OCCASIONAL IFR CONDITIONS TO PLN LATE TONIGHT...WITH WEAKER SNOW SHOWERS IN THE VICINITY OF TVC...AND LITTLE AT APN. THE MAIN SHOW WILL OCCUR DURING THE DAYLIGHT HOURS ON SATURDAY...AS AN UPPER LEVEL DISTURBANCE BRINGS MUCH DEEPER MOISTURE TO THE REGION. LOW LEVEL WINDS REMAIN SW...RESULTING IN PREVAILING LIFR CONDITIONS AT PLN IN FALLING AND BLOWING SNOW...IFR AT TIMES AT TVC...AND LOW-END MVFR LATE IN THE DAY AT APN. JZ && .DISCUSSION...ISSUED 404 PM FRI NOV 23... PRIMARY FORECAST CHALLENGE OVER THE NEXT 24 HOURS REMAINS LAKE EFFECT/ENHANCED SNOWFALL AND AMOUNTS...AND WHAT/IF ANY HEADLINES MAY BE NEEDED. EARLY AFTERNOON ANALYSIS PLACES MUCH OF NORTHERN MICHIGAN ON THE BACKSIDE OF LOW LEVEL RIDGE AXIS EXTENDING FROM THE MID MISS VALLEY UP THROUGH EASTERN ONTARIO...WHILE ALOFT...WEAK SHORTWAVE RIDGING BUILDING ACROSS THE REGION IN ADVANCE SHORTWAVE ENERGY DROPPING THROUGH THE NORTHERN HIGH PLAINS. OVERALL LOW LEVEL FLOW REGIME HAS BEEN IN TRANSIT THROUGH THE DAY...STARTING NORTH/NORTHWEST AND ENDING UP MORE WEST/SOUTHWEST AS OF 19Z...WITH A CORRESPONDING SHIFT IN LAKE EFFECT SNOW SHOWERS TOWARD THE WSW FAVORED LOCATIONS. DESPITE RATHER SCANT 900-700MB MOISTURE INITIALLY...LATEST RUC/SATELLITE ANALYSIS SHOWS AN UPTICK IN BOUNDARY LAYER RH GIVEN INCREASINGLY LONG FETCH ACROSS LAKE MICHIGAN. SNOWFALL AMOUNTS THROUGH THE DAY HAVE BEEN RATHER IMPRESSIVE IN A FEW SPOTS...NAMELY OWING TO PRONOUNCED STUBBORN LOW LEVEL CONVERGENCE AS A WEAK WARM FRONT SNUCK ITS WAY NORTH THROUGH THE DAY. BIGGEST WINNERS SO FAR - CHARLEVOIX AND EMMET COUNTIES...WHERE SEVERAL REPORTS OF 3 TO AS MUCH AS LOCALLY 5 INCHES HAVE BEEN NOTED...VERY MUCH IN LINE WITH LATEST KAPX RADAR STORM TOTAL SNOW GRAPHICS. FOR TONIGHT...OVERALL PATTERN PROGGED TO CHANGE VERY LITTLE AS PERSISTENT WEST TO SOUTHWESTERLY FLOW REMAINS INTACT AHEAD OF APPROACHING LOW/MID LEVEL TROUGH. PLENTY OF OVER-LAKE INSTABILITY TO WORK WITH (OBVIOUSLY GIVEN ONGOING SNOWS)...WITH H85 TEMPS PROGGED TO "WARM" JUST SLIGHTLY TO AROUND -10C BY 12Z TOMORROW. 900-700MB RH ALSO QUITE CONDUCIVE FOR LES...WITH VALUES ON THE RISE TO 80 PERCENT OR BETTER OVERNIGHT PER CONTINUED LONG FETCH UP LAKE MICHIGAN. DIFFICULT TO FIND ANY REASON WHY SNOWS WON/T CONTINUE THROUGH MUCH OF THE NIGHT AS WEST/SOUTHWEST FLOW HOLDS STATUS QUO...AND INCREASING GRADIENT ACTS TO PREVENT ANY LAND BREEZES THAT COULD POTENTIALLY TRY TO SHOVE ANY SNOW BANDS FARTHER OFFSHORE. USING THE 15Z SREF POP MEAN AS GUIDANCE...WILL HANG THE HIGHEST POPS ACROSS EMMET AND SOUTHERN MACKINAC COUNTIES (I.E. W/SW FLOW AREAS)...AND WILL RUN WITH A WARNING ACROSS EMMET (GIVEN ALREADY SNOWY CONDITIONS THIS AFTERNOON) AND AN ADVISORY FOR MACKINAC (WITH A HIGHER CRITERIA FOR WARNING). HEADING INTO TOMORROW...UPPER WAVE PROGGED TO SWING THROUGH THE REGION BETWEEN 15Z AND 21Z...WITH AXIS OF DECENT 700-500MB -DIVQ AND MUCH DEEPER PLUME OF MOISTURE (1000-500MB RH INCREASES TO BETTER THAN 90 PERCENT) ANNOUNCING THE LIKELIHOOD OF A SYNOPTIC COMPONENT TO THE EVENT. CONTINUED WEST/SOUTHWEST LOW LEVEL FLOW REGIME SHOULD EASILY CONTRIBUTE TO ENHANCEMENT ACROSS THE STRAITS REGION...HOWEVER WILL BE DEALING WITH SOME POSSIBLE PTYPE ISSUES ALONG THE IMMEDIATE COAST GIVEN LONG PERIOD OF ONSHORE FLOW...WITH FORECAST RAOBS INDICATING FREEZING LEVELS ABOUT 1500 FT AGL. SOME QUESTION WHETHER THIS WILL BE SUFFICIENT FOR MELTING...AND PROBABLY DEPENDENT ON INTENSITY OF PRECIP. HOWEVER...FOR SIMPLICITY...WILL HOLD PRECIP ALL SNOW. OUTSIDE OF THE LAKE ENHANCEMENT...OVERALL INCREASING SYNOPTIC SUPPORT SHOULD BE SUFFICIENT TO GENERATE SOME LIGHT SNOW FROM WEST TO EAST AS -DIVQ AXIS ADVANCES ACROSS NORTHERN MICHIGAN...BUT DOUBTFUL OF MUCH IN THE WAY OF ACCUMULATION GIVEN EXPECTED HIGHS IN THE LOWER/MIDDLE 30S UNDER INCREASING LOW LEVEL WARM ADVECTION AND OVERALL WEAK FORCING. ON THE MARINE SIDE...INCREASINGLY GUSTY WINDS AND BUILDING WAVES EXPECTED ON THE LAKE MICHIGAN SIDE LATE TONIGHT AND ESPECIALLY TOMORROW MORNING AS GRADIENT TIGHTENS...WITH WINDS AT THE TOP OF THE INSTABILITY-MIXED LAYER RUNNING ABOUT 35-40 KNOTS. COUPLED WITH COASTAL CONVERGENCE SHOULD EASILY SEE GUSTS IN THE GALE RANGE...WITH GALE CONDITIONS SPREADING TO OTHER NEARSHORE AREAS BY EARLY AFTERNOON AS CORE OF STRONGER 900-850MB WINDS SPREADS EAST. LAWRENCE SATURDAY NIGHT INTO SUNDAY...SOUTHWEST FLOW LAKE EFFECT IS EXPECTED TO WIND DOWN SATURDAY NIGHT AS THE SHORTWAVE TROUGH MOVES EAST OF THE REGION. 850-700MB RH FALLS FROM 55-65 PCT AT 00Z SUN TO 45-55 PCT BY 12Z AND INVERSION HEIGHTS LOWER FROM AROUND 6KFT TO ABOUT 3KFT OVER THAT SAME TIME PERIOD. THIS ALL POINTS TO A DIMINISHING TREND OF LES ACTIVITY WITH MOST ACCUMULATIONS ARRIVING DURING THE EVENING AND WILL GO UP TO A HALF INCH OVER SOUTHERN MACKINAC AND NORTHERN EMMET COUNTIES. MID-LEVEL DRY AIR WILL CONTINUE TO POUR INTO THE AREA ON SUNDAY AS 850MB TEMPS MODERATE BETWEEN -3C TO -6C IN THE MORNING TO NEAR 0C BY EARLY IN THE EVENING. BELIEVE ANY LINGERING LOW LEVEL INSTABILITY WILL BE TOO SHALLOW FOR ANY LES ACTIVITY AND WILL KEEP SNOW CHANCES OUT OF THE FORECAST. MOISTURE ALONG THE LOW LEVEL BAROCLINIC ZONE WILL MOVE NE INTO ONTARIO AS WILL MID-UPPER LEVEL MOISTURE ALONG THE SOUTHERN FRINGES OF THE JET STREAM. SO WITH THE DEPARTING MOISTURE ACROSS THE NORTHERN CWA...LOOKS LIKE SOME SUNSHINE WILL BE HAD ON SUNDAY WITH HIGHS RANGING FROM THE UPPER 30S NORTH TO MID 40S SOUTH. SUNDAY NIGHT INTO MONDAY...SURFACE LOW PRESSURE AHEAD OF A MID- LEVEL WAVE OVER THE NORTHERN PLAINS WILL TRACK ALONG ITS WARM FRONT ACROSS SOUTHERN ONTARIO. AHEAD OF THE SURFACE LOW...SW WINDS WILL BRING RELATIVELY WARM AIR (850MB TEMPS BETWEEN -3C AND 0C) INTO MICHIGAN...WHICH WILL LEAD TO LOWS IN THE UPPER 20S TO MIDDLE 30S. DRY AIR OVER THE AREA SUNDAY NIGHT WILL EVENTUALLY LOSE OUT TO INCREASING MOISTURE AHEAD OF A NE MOVING SURFACE LOW OUT OF THE SOUTHERN PLAINS...WHICH GETS PICKED UP BY THE AFOREMENTIONED PACIFIC WAVE. THIS LOW WILL TRAVEL INTO THE LOWER OHIO RIVER VALLEY BY MIDDAY TO CENTRAL OHIO BY 00Z TUE. NORTHERN PERIPHERY OF THE DEFORMATION ZONE ON THE NW SIDE OF THE LOW STILL LOOKS TO CLIP COUNTIES NEAR SAGINAW BAY. STILL HARD TO SAY IF PRECIP WILL MAKE HERE SINCE INITIAL DRY AIRMASS WILL NEED TO BE OVERCOME. WILL TAKE OUT PRECIP CHANCES FOR THE MORNING DUE TO THIS REASON BUT WILL LEAVE A LOW CHANCE OF RAIN FOR THE AFTERNOON GIVEN 850MB TEMPS AROUND 0C AND SURFACE TEMPS AROUND 40F. PASSAGE OF AN 850MB TROUGH DURING THE AFTERNOON WILL HELP SWITCH THE WINDS TO THE NW AND ADVECT IN COOLER AIR...BUT NOT COOL ENOUGH FOR LAKE EFFECT PRECIP TO BE GENERATED. HIGHS WILL BE IN THE UPPER 30S TO LOW 40S. TUESDAY THROUGH FRIDAY...MODELS HAVE A LITTLE BETTER HANDLE ON THE NEXT SW LOW DUE TO PASS ACROSS THE OHIO VALLEY ON MONDAY AND INTO THE EASTERN GREAT LAKES ON TUESDAY...BUT STILL HAVE THEIR DIFFERENCES...SPECIFICALLY WITH THE SPEED OF THE SYSTEM. BEYOND TUESDAY...LOW CONFIDENCE EXISTS WITH LOW PRESSURE DEVELOPMENT MID TO LATE NEXT WEEK. PUT HIGHER FAITH IN THE ENSEMBLES THAN ANY ONE PARTICULAR MODEL RUN. TUESDAY...LOW PRESSURE WILL MOVE FROM THE OHIO RIVER VALLEY NE INTO NEW ENGLAND. THE 06Z GFS IS ON THE NORTHERN EDGE OF ENSEMBLE MEMBERS WHILE THE 00Z ECMWF IS ON THE QUICKER SIDE...SO TRIED TO TAKE A MORE CONSENSUS TRACK. THIS WOULD PLACE THE SOUTHEAST CWA ON THE EDGE OF THE DEFORMATION ZONE MONDAY NIGHT. AN INVERTED TROUGH WILL EMANATE FROM THIS LOW AND MOVE ACROSS THE CWA AS THE SURFACE LOW PASSES TO OUR SE. WINDS BEHIND THIS TROUGH WILL SWITCH TO THE NW AND BRING IN COLDER AIR WHICH HAS THE CHANCE TO START UP LAKE EFFECT PROCESSES. 06Z GFS IS ON THE COLDER EDGE OF GUIDANCE AND WILL TEMPER EXPECTATIONS ON HOW QUICK THE COLDER AIR MOVES IN...ESPECIALLY SINCE 00Z GFS ENSEMBLE HAS SLOWED THE PROGRESSION OF THE COLDER AIR INTO THE AREA. BUT WITH THE GENERAL LOW LEVEL CYCLONIC FLOW...AND QUESTION MARKS WITH LAKE EFFECT PROCESSES...WILL LEAVE A GENERAL LOW CHANCE POP MONDAY NIGHT. MEANWHILE...NORTHERN STREAM ENERGY ROTATING AROUND THE POLAR VORTEX WILL SKIRT BY TO THE NORTH WITHOUT MUCH IMPACT. ALTHOUGH THE CORE OF THE COLD AIR WILL SKIRT BY TO THE NORTH...COLD AIR ADVECTION WILL CONTINUE DURING THE DAY AS 850MB TEMPS FALL INTO THE LOWER TEENS. HOWEVER...VERY DRY AIR WILL POUR INTO THE NORTHERN GREAT LAKES BEHIND THE SURFACE LOW...AND DO NOT EXPECT A LARGE LAKE EFFECT EVENT. HIGHS WILL BE IN THE MIDDLE TO UPPER 30S. WEDNESDAY...HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE STATE. ANY LIGHT LAKE EFFECT WILL CONTINUE INTO TUESDAY NIGHT...WHILE MID-HIGH CLOUDS WILL STREAM ACROSS THE AREA WITH SW ALOFT. DRY LOW LEVELS WITH THE SURFACE RIDGE AXIS PRESENT WILL TRY TO KEEP THE AREA PRECIP FREE DESPITE 850MB TEMPS AROUND -10C. SO WILL GO WITH A DRY BUT MOSTLY CLOUDY DAY WITH HIGHS IN THE LOWER TO MIDDLE 30S. THURSDAY THROUGH FRIDAY...CONFIDENCE LOW DURING THIS PERIOD...ALL STEMMING FROM THE STRENGTH OF SURFACE LOW AS THE NEXT PACIFIC WAVE EMERGES FROM THE ROCKIES. 06Z GFS/00Z ECMWF LEAVE THE DOOR OPEN FOR A STRONGER SURFACE WAVE THAT WOULD PASS ACROSS THE CENTRAL GREAT LAKES WEDNESDAY NIGHT...BUT THEIR SOLUTIONS DO NOT HAVE MUCH SUPPORT FROM THE GFS ENSEMBLE MEMBERS. WILL INCREASE POPS HEADING INTO THURSDAY AS SOME SORT OF SURFACE FEATURE PASSES TO THE SOUTH...THEN KEEP A CHANCE OF SNOW FOR FRIDAY FOR THE LAKE EFFECT SNOW BELTS AS COLDER AIR WRAPS IN BEHIND ANY SYSTEM. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST SATURDAY FOR MIZ015. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SATURDAY FOR MIZ016. LM...GALE WARNING FROM 7 AM SATURDAY TO 11 AM EST SUNDAY FOR LMZ323- 341-342-344>346. LH...GALE WARNING FROM 7 AM SATURDAY TO 11 AM EST SUNDAY FOR LHZ345>349. LS...GALE WARNING FROM 7 AM SATURDAY TO 5 AM EST SUNDAY FOR LSZ321- 322. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 625 PM EST FRI NOV 23 2007 UPDATED FOR 00Z AVIATION SECTION .SHORT TERM (TONIGHT AND SAT)... MAIN FCST ISSUE REVOLVES AROUND LES. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE ALONG THE W COAST OF NAMERICA WITH THE DOWNSTREAM TROF DOMINATING MUCH OF CNTRL/ERN NAMERICA. IN THE NW FLOW...ONE SHORTWAVE IS OVER NRN ONTARIO WITH A STRONGER SHORTWAVE DROPPING TOWARD NRN SASKATCHEWAN/MANITOBA. WAA REGIME IN RESPONSE TO THE ONTARIO SHORTWAVE HAS BROUGHT A BAND OF MID CLOUDS AND STRATOCU INTO UPPER MI TODAY. SOME FLURRIES HAVE ALSO OCCURRED OVER THE WRN FCST AREA. MEANWHILE...THE LOW-LEVEL SW FLOW THAT HAS DEVELOPED HAS SHIFTED WHAT IS LEFT OF LES COMPLETELY OFFSHORE OF UPPER MI. EARLIER TODAY...THERE WAS A DOMINANT BAND CLOSE TO THE N SHORE OF MN EXTENDING NE TO JUST N OF ISLE ROYALE. IT APPEARS MUCH OF THAT BAND HAS BROKEN UP. IT`S DIFFICULT TO TELL WHAT IS HAPPENING NOW AS HIGHER CLOUDS ARE OBSCURING LAKE EFFECT...BUT THERE ARE SOME HINTS THAT LES IS OCCURRING BTWN THE KEWEENAW AND ISLE ROYALE. WITH 850MB TEMPS RISING NO HIGHER THAN -9C TONIGHT...LES WILL CONTINUE TO BE A POSSIBILITY...AND ONGOING SW FLOW WILL ALLOW FOR THE POTENTIAL OF LONG FETCH SW-NE ORIENTED LES BANDS OVER WRN LAKE SUPERIOR. AS SHORTWAVE OVER NRN ONTARIO HEADS ESE...SFC TROF NOW EXTENDING FROM NRN ONTARIO TO FAR NW MN WILL SLIP OVER LAKE SUPERIOR TONIGHT. THIS WILL ENHANCE THE CONVERGENCE...PROMOTING THE DEVELOPMENT OF A DOMINANT BAND ALONG THE TROF. ALL THE MODELS SUGGEST THIS...BUT THE RUC13 AND LOCALLY RUN HIGH RES WRF-ARW ARE MUCH MORE WELL-DEFINED WITH THE BAND. SO THE QUESTION IS...WILL THE WINDS BECOME WRLY ENOUGH TO PUSH THIS BAND TO THE KEWEENAW. CURRENTLY...PRES RISES BEHIND THE SFC TROF ARE WEAKENING TO THE POINT THAT THERE ARE ALMOST NO RISES NOTED IN THE LAST 3HRS...AND PRES FALLS ARE ALREADY INCREASING AND SPREADING S INTO SCNTRL CANADA AHEAD OF THE STRONGER SHORTWAVE DROPPING S IN NRN CANADA. THUS...IT WOULD APPEAR THE TROF/WIND SHIFT WILL NOT MAKE SIGNIFICANT PROGRESS ACROSS THE LAKE. HOWEVER...WITH SOME UNCERTAINTY...WILL KEEP CHC POPS N OF HOUGHTON OVERNIGHT AND JUST BRUSH THE SHORE OF KEWEENAW COUNTY WITH LIKELY POPS AND ABOUT 1 INCH OF ACCUMULATION. EVENING SHIFT WILL PROBABLY BE ABLE TO SHIFT HIGHER POPS OFFSHORE OF THE KEWEENAW IF UPSTREAM PRES FALLS BECOME MORE SIGNIFICANT BEHIND TROF. AS FOR LES NEAR LAKE MICHIGAN...SW FLOW WILL HAVE ENOUGH WRLY COMPONENT TO KEEP ANY LES OFF LAKE MICHIGAN E OF THE FCST AREA. AWAY FROM THE POSSIBLE LES OVER THE KEWEENAW...MAINTAINED A MENTION OF SLIGHT CHC -SHSN OVERNIGHT ACROSS THE FCST AREA AS SFC OBS/RADAR INDICATE SOME -SN/FLURRIES IN THE VCNTY OF SFC TROF. SHORTWAVE CURRENTLY DROPPING TOWARD SASKATCHEWAN/MANITOBA WILL REACH NRN ONTARIO SAT. AS A RESULT...WIND DIRECTION WILL CHANGE LITTLE FOR MOST OF SAT. SO...THE TIP OF THE KEWEENAW REMAINS THE ONLY LOCATION FOR ANY LES CONCERNS. SINCE THERE IS A HINT THAT THE 850MB WINDS TAKE ON A MORE WRLY DIRECTION SAT AFTN...THE POTENTIAL FOR LES ON THE KEWEENAW SHOULD IMPROVE DURING THE DAY. IF LES DOES NOT REACH THAT AREA TONIGHT...IT SHOULD SAT AFTN. GIVEN THE UNCERTAINTY...KEPT SNOW AMOUNTS CONSERVATIVE WITH JUST 1 TO MAYBE 3 INCHES NORTH OF HOUGHTON. LONGER TERM...00Z SUN ONWARD... NAM SHOWING 500 MB FLOW GETTING ZONAL ON SUN AFTER TROUGH AXIS PASSES THROUGH EARLY SAT NIGHT WITH TROUGHING FOR MON. THERE IS A NARROW RIBBON OF MOISTURE ON THE I280K-I295K SURFACES ON THE NAM ACROSS SOUTHERN AND CENTRAL LAKE SUPERIOR SAT NIGHT THAT SHIFTS TO THE NORTH ON SUN. GFS SHOWS THIS AS WELL ON I280K-I300K SURFACES ALONG WITH BOTH MODELS SHOWING SOME WEAK 850-500 MB Q-VECTOR CONVERGENCE WHICH REMAINS ON SUN ACROSS THE CWA. WITH WEST WINDS ON SAT NIGHT THROUGH SUN MORNING...THE KEWEENAW COULD SEE SOME DECENT SNOW WITH A POSSIBLE SEEDER FEEDER MECHANISM SETTING UP TO HELP THE SNOWFALL RATES ALONG. GFS SOUNDINGS FOR KCMX AND KP59 SHOW INVERSION HEIGHTS ABOUT 5000 FEET THEN AND THIS FALLS LATE SAT NIGHT INTO SUN MORNING. PROBLEM LATE SAT NIGHT INTO SUN MORNING IS THERE IS WARMING AT 850 MB FROM -8C TO -10C TO -6C TO -8C BY 12Z SUN AND THEN 850 MB TEMPERATURES WARM MORE AFTER THAT AND THE WIND TURNS SOUTHERLY BY 18Z SUN. LAKE EFFECT COMBINED WITH THE NARROW RIBBON OF MOISTURE IN THE LOW AND MID LEVELS WILL GIVE SNOWFALL AMOUNTS UP TO 6 INCHES SAT NIGHT INTO SUN MORNING OVER THE KEWEENAW WITH THE RIBBON OF MOISTURE CONFINED TO THE NORTHERN CWA AT THAT TIME AND THIS WILL STILL NEED TO BE WATCHED AS THIS COULD BE ADVISORY AMOUNT SNOW OR JUST BELOW ADVISORY DEPENDING ON HOW AND WHERE THE LAKE EFFECT SNOWBAND SETS UP AND IF IT MOVES BACK AND FORTH AT ALL. THIS IS THE ONLY SPOT THAT WOULD SEE SIGNIFICANT SNOW WITH THE LAKE EFFECT COMBINED WITH THE NARROW RIBBON OF MOISTURE. WILL GO UNDERNEATH ADVISORY AMOUNTS FOR NOW AS GFS SOUNDINGS SHOW THE LOWEST LEVELS AGAIN HAVE AN INVERTED-V SOUNDING LOOK TO THEM WITH SOME DRY AIR AND THIS SHOULD CUT INTO AMOUNTS A BIT. OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST EXCEPT TO GO LIKELY OVER THE KEWEENAW PENINSULA WITH THE LAKE EFFECT SNOW BAND AND THE SYNOPTIC MOISTURE AROUND. FOR TEMPERATURES...DID NOT MAKE ANY CHANGES OR VERY LITTLE CHANGE TO THE GOING FORECAST. IN THE EXTENDED...GFS...ECMWF AND CANADIAN MODELS ALL SHOW THE 500 MB PATTERN CONSISTS OF A TROUGH MOVING INTO THE UPPER GREAT LAKES 00Z TUE WITH A SHORTWAVE RIDGE AFFECTING THE AREA 00Z WED. ANOTHER TROUGH MOVES IN FOR 00Z THU AND FOR 00Z FRI WITH RIDGING FOR 00Z SAT. WE END UP GETTING TWO STORMS WITH THE FIRST ON MON AND THE NEXT ON WED AND THU. THE ONE FOR WED AND THU COULD BE A SIGNIFICANT SNOW PRODUCER BEHIND IT WITH LAKE EFFECT SNOW AND STRONG NORTH TO NORTHWEST WINDS. WILL HAVE TO WATCH THIS ONE WITH ITS TRACK ANYWAY. WENT CLOSE TO 06Z GFS AND 00Z ECMWF FOR THIS FORECAST. TEMPERATURES LOOK TO BE COLDER THAN NORMAL IN THE EXTENDED STARTING ON WED AND WENT CLOSE TO ADJMXR FOR LOWS AND HIGHS. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL AT KSAW THRU THIS FCST PERIOD. THERE MIGHT BE A FEW FLURRIES LATE IN THE NIGHT AND SAT MORNING...BUT NO VIS RESTRICTION IS EXPECTED. AT KCMX...VFR CONDITIONS WILL PREVAIL WHILE AWAITING THE EVOLUTION OF LAKE EFFECT -SHSN OVER WRN LAKE SUPERIOR. IT REMAINS VERY UNCERTAIN WHETHER THE WINDS WILL VEER WRLY ENOUGH LATE TONIGHT OR SAT MORNING TO BRING WHAT COULD BE A FAIRLY SIGNIFICANT DOMINANT SNOW BAND ONSHORE AS FAR S AS KCMX. WITH LOW CONFIDENCE...TENTATIVELY INCLUDED MVFR VIS IN -SHSN MID MORNING SAT BASED ON SUGGESTION FROM SOME OF THE HIGHER RESOLUTION FORECAST MODELS THAT WINDS WILL VEER ENOUGH TO THE W. CONDITIONS COULD REMAIN VFR OR DROP TO IFR DEPENDING ON VERY SUBTLE CHANGES IN WIND DIRECTION. WHETHER OR NOT SNOW DEVELOPS...WINDS WILL LIKELY BECOME RATHER GUSTY IN THE AFTERNOON. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FCST CONCERN CONTINUES TO BE THE POTENTIAL OF GALES SAT/SAT NIGHT. LATEST ROUND OF FCST GUIDANCE SUPPORTS THE THINKING OF THE LAST COUPLE OF DAYS THAT WSW GALES WILL IN FACT OCCUR SAT AFTN/EVENING AS PRES GRADIENT TIGHTENS AHEAD OF A LOW PRES TROF DROPPING SE TOWARD LAKE SUPERIOR. HAVE THUS ISSUED GALE WARNINGS FOR THE OPEN WATERS OF LAKE SUPERIOR SAT AFTN/NIGHT. BEFORE THE GALES BEGIN...STIFF SW WINDS OF 20-30KT WILL DOMINATE TONIGHT/SAT MORNING WITH THE STRONGEST WINDS PROBABLY BTWN THE KEWEENAW AND ISLE ROYALE. ANOTHER ROUND OF GALES...THIS TIME N TO NW GALES...MAY OCCUR LATE WED AS DEEPENING LOW PRES MOVES NE INTO THE GREAT LAKES REGION. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING 1 PM SAT TO MIDNIGHT EST SAT NIGHT LSZ263-264. GALE WARNING 4 PM SAT TO 3 AM EST SUN LSZ265>267. && $$ SHORT TERM...ROLFSON LONG TERM...GJM AVIATION...ROLFSON/TAG MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 435 PM EST FRI NOV 23 2007 .SHORT TERM (TONIGHT AND SAT)... MAIN FCST ISSUE REVOLVES AROUND LES. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE ALONG THE W COAST OF NAMERICA WITH THE DOWNSTREAM TROF DOMINATING MUCH OF CNTRL/ERN NAMERICA. IN THE NW FLOW...ONE SHORTWAVE IS OVER NRN ONTARIO WITH A STRONGER SHORTWAVE DROPPING TOWARD NRN SASKATCHEWAN/MANITOBA. WAA REGIME IN RESPONSE TO THE ONTARIO SHORTWAVE HAS BROUGHT A BAND OF MID CLOUDS AND STRATOCU INTO UPPER MI TODAY. SOME FLURRIES HAVE ALSO OCCURRED OVER THE WRN FCST AREA. MEANWHILE...THE LOW-LEVEL SW FLOW THAT HAS DEVELOPED HAS SHIFTED WHAT IS LEFT OF LES COMPLETELY OFFSHORE OF UPPER MI. EARLIER TODAY...THERE WAS A DOMINANT BAND CLOSE TO THE N SHORE OF MN EXTENDING NE TO JUST N OF ISLE ROYALE. IT APPEARS MUCH OF THAT BAND HAS BROKEN UP. IT`S DIFFICULT TO TELL WHAT IS HAPPENING NOW AS HIGHER CLOUDS ARE OBSCURING LAKE EFFECT...BUT THERE ARE SOME HINTS THAT LES IS OCCURRING BTWN THE KEWEENAW AND ISLE ROYALE. WITH 850MB TEMPS RISING NO HIGHER THAN -9C TONIGHT...LES WILL CONTINUE TO BE A POSSIBILITY...AND ONGOING SW FLOW WILL ALLOW FOR THE POTENTIAL OF LONG FETCH SW-NE ORIENTED LES BANDS OVER WRN LAKE SUPERIOR. AS SHORTWAVE OVER NRN ONTARIO HEADS ESE...SFC TROF NOW EXTENDING FROM NRN ONTARIO TO FAR NW MN WILL SLIP OVER LAKE SUPERIOR TONIGHT. THIS WILL ENHANCE THE CONVERGENCE...PROMOTING THE DEVELOPMENT OF A DOMINANT BAND ALONG THE TROF. ALL THE MODELS SUGGEST THIS...BUT THE RUC13 AND LOCALLY RUN HIGH RES WRF-ARW ARE MUCH MORE WELL-DEFINED WITH THE BAND. SO THE QUESTION IS...WILL THE WINDS BECOME WRLY ENOUGH TO PUSH THIS BAND TO THE KEWEENAW. CURRENTLY...PRES RISES BEHIND THE SFC TROF ARE WEAKENING TO THE POINT THAT THERE ARE ALMOST NO RISES NOTED IN THE LAST 3HRS...AND PRES FALLS ARE ALREADY INCREASING AND SPREADING S INTO SCNTRL CANADA AHEAD OF THE STRONGER SHORTWAVE DROPPING S IN NRN CANADA. THUS...IT WOULD APPEAR THE TROF/WIND SHIFT WILL NOT MAKE SIGNIFICANT PROGRESS ACROSS THE LAKE. HOWEVER...WITH SOME UNCERTAINTY...WILL KEEP CHC POPS N OF HOUGHTON OVERNIGHT AND JUST BRUSH THE SHORE OF KEWEENAW COUNTY WITH LIKELY POPS AND ABOUT 1 INCH OF ACCUMULATION. EVENING SHIFT WILL PROBABLY BE ABLE TO SHIFT HIGHER POPS OFFSHORE OF THE KEWEENAW IF UPSTREAM PRES FALLS BECOME MORE SIGNIFICANT BEHIND TROF. AS FOR LES NEAR LAKE MICHIGAN...SW FLOW WILL HAVE ENOUGH WRLY COMPONENT TO KEEP ANY LES OFF LAKE MICHIGAN E OF THE FCST AREA. AWAY FROM THE POSSIBLE LES OVER THE KEWEENAW...MAINTAINED A MENTION OF SLIGHT CHC -SHSN OVERNIGHT ACROSS THE FCST AREA AS SFC OBS/RADAR INDICATE SOME -SN/FLURRIES IN THE VCNTY OF SFC TROF. SHORTWAVE CURRENTLY DROPPING TOWARD SASKATCHEWAN/MANITOBA WILL REACH NRN ONTARIO SAT. AS A RESULT...WIND DIRECTION WILL CHANGE LITTLE FOR MOST OF SAT. SO...THE TIP OF THE KEWEENAW REMAINS THE ONLY LOCATION FOR ANY LES CONCERNS. SINCE THERE IS A HINT THAT THE 850MB WINDS TAKE ON A MORE WRLY DIRECTION SAT AFTN...THE POTENTIAL FOR LES ON THE KEWEENAW SHOULD IMPROVE DURING THE DAY. IF LES DOES NOT REACH THAT AREA TONIGHT...IT SHOULD SAT AFTN. GIVEN THE UNCERTAINTY...KEPT SNOW AMOUNTS CONSERVATIVE WITH JUST 1 TO MAYBE 3 INCHES NORTH OF HOUGHTON. LONGER TERM...00Z SUN ONWARD... NAM SHOWING 500 MB FLOW GETTING ZONAL ON SUN AFTER TROUGH AXIS PASSES THROUGH EARLY SAT NIGHT WITH TROUGHING FOR MON. THERE IS A NARROW RIBBON OF MOISTURE ON THE I280K-I295K SURFACES ON THE NAM ACROSS SOUTHERN AND CENTRAL LAKE SUPERIOR SAT NIGHT THAT SHIFTS TO THE NORTH ON SUN. GFS SHOWS THIS AS WELL ON I280K-I300K SURFACES ALONG WITH BOTH MODELS SHOWING SOME WEAK 850-500 MB Q-VECTOR CONVERGENCE WHICH REMAINS ON SUN ACROSS THE CWA. WITH WEST WINDS ON SAT NIGHT THROUGH SUN MORNING...THE KEWEENAW COULD SEE SOME DECENT SNOW WITH A POSSIBLE SEEDER FEEDER MECHANISM SETTING UP TO HELP THE SNOWFALL RATES ALONG. GFS SOUNDINGS FOR KCMX AND KP59 SHOW INVERSION HEIGHTS ABOUT 5000 FEET THEN AND THIS FALLS LATE SAT NIGHT INTO SUN MORNING. PROBLEM LATE SAT NIGHT INTO SUN MORNING IS THERE IS WARMING AT 850 MB FROM -8C TO -10C TO -6C TO -8C BY 12Z SUN AND THEN 850 MB TEMPERATURES WARM MORE AFTER THAT AND THE WIND TURNS SOUTHERLY BY 18Z SUN. LAKE EFFECT COMBINED WITH THE NARROW RIBBON OF MOISTURE IN THE LOW AND MID LEVELS WILL GIVE SNOWFALL AMOUNTS UP TO 6 INCHES SAT NIGHT INTO SUN MORNING OVER THE KEWEENAW WITH THE RIBBON OF MOISTURE CONFINED TO THE NORTHERN CWA AT THAT TIME AND THIS WILL STILL NEED TO BE WATCHED AS THIS COULD BE ADVISORY AMOUNT SNOW OR JUST BELOW ADVISORY DEPENDING ON HOW AND WHERE THE LAKE EFFECT SNOWBAND SETS UP AND IF IT MOVES BACK AND FORTH AT ALL. THIS IS THE ONLY SPOT THAT WOULD SEE SIGNIFICANT SNOW WITH THE LAKE EFFECT COMBINED WITH THE NARROW RIBBON OF MOISTURE. WILL GO UNDERNEATH ADVISORY AMOUNTS FOR NOW AS GFS SOUNDINGS SHOW THE LOWEST LEVELS AGAIN HAVE AN INVERTED-V SOUNDING LOOK TO THEM WITH SOME DRY AIR AND THIS SHOULD CUT INTO AMOUNTS A BIT. OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST EXCEPT TO GO LIKELY OVER THE KEWEENAW PENINSULA WITH THE LAKE EFFECT SNOW BAND AND THE SYNOPTIC MOISTURE AROUND. FOR TEMPERATURES...DID NOT MAKE ANY CHANGES OR VERY LITTLE CHANGE TO THE GOING FORECAST. IN THE EXTENDED...GFS...ECMWF AND CANADIAN MODELS ALL SHOW THE 500 MB PATTERN CONSISTS OF A TROUGH MOVING INTO THE UPPER GREAT LAKES 00Z TUE WITH A SHORTWAVE RIDGE AFFECTING THE AREA 00Z WED. ANOTHER TROUGH MOVES IN FOR 00Z THU AND FOR 00Z FRI WITH RIDGING FOR 00Z SAT. WE END UP GETTING TWO STORMS WITH THE FIRST ON MON AND THE NEXT ON WED AND THU. THE ONE FOR WED AND THU COULD BE A SIGNIFICANT SNOW PRODUCER BEHIND IT WITH LAKE EFFECT SNOW AND STRONG NORTH TO NORTHWEST WINDS. WILL HAVE TO WATCH THIS ONE WITH ITS TRACK ANYWAY. WENT CLOSE TO 06Z GFS AND 00Z ECMWF FOR THIS FORECAST. TEMPERATURES LOOK TO BE COLDER THAN NORMAL IN THE EXTENDED STARTING ON WED AND WENT CLOSE TO ADJMXR FOR LOWS AND HIGHS. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL AT KSAW THRU THIS FCST PERIOD. THERE MIGHT BE A FEW FLURRIES LATE IN THE NIGHT AND SAT MORNING...BUT NO VIS RESTRICTION IS EXPECTED. AT KCMX...VFR CONDITIONS WILL PREVAIL WHILE AWAITING THE EVOLUTION OF LAKE EFFECT -SHSN OVER WRN LAKE SUPERIOR. IT IS VERY UNCERTAIN WHETHER THE WINDS WILL VEER WRLY ENOUGH LATE TONIGHT OR SAT MORNING TO BRING WHAT COULD BE A FAIRLY SIGNIFICANT DOMINANT SNOW BAND ONSHORE AS FAR S AS KCMX. WITH LOW CONFIDENCE...TENTATIVELY INCLUDED MVFR VIS IN -SHSN MID MORNING SAT BASED ON SUGGESTION FROM SOME OF THE HIGHER RESOLUTION FORECAST MODELS THAT WINDS WILL VEER ENOUGH TO THE W. CONDITIONS COULD REMAIN VFR OR DROP TO IFR DEPENDING ON VERY SUBTLE CHANGES IN WIND DIRECTION. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FCST CONCERN CONTINUES TO BE THE POTENTIAL OF GALES SAT/SAT NIGHT. LATEST ROUND OF FCST GUIDANCE SUPPORTS THE THINKING OF THE LAST COUPLE OF DAYS THAT WSW GALES WILL IN FACT OCCUR SAT AFTN/EVENING AS PRES GRADIENT TIGHTENS AHEAD OF A LOW PRES TROF DROPPING SE TOWARD LAKE SUPERIOR. HAVE THUS ISSUED GALE WARNINGS FOR THE OPEN WATERS OF LAKE SUPERIOR SAT AFTN/NIGHT. BEFORE THE GALES BEGIN...STIFF SW WINDS OF 20-30KT WILL DOMINATE TONIGHT/SAT MORNING WITH THE STRONGEST WINDS PROBABLY BTWN THE KEWEENAW AND ISLE ROYALE. ANOTHER ROUND OF GALES...THIS TIME N TO NW GALES...MAY OCCUR LATE WED AS DEEPENING LOW PRES MOVES NE INTO THE GREAT LAKES REGION. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING 1 PM SAT TO MIDNIGHT EST SAT NIGHT LSZ263-264. GALE WARNING 4 PM SAT TO 3 AM EST SUN LSZ265>267. && $$ SHORT TERM...ROLFSON LONG TERM...GJM AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 404 PM EST FRI NOV 23 2007 .DISCUSSION...PRIMARY FORECAST CHALLENGE OVER THE NEXT 24 HOURS REMAINS LAKE EFFECT/ENHANCED SNOWFALL AND AMOUNTS...AND WHAT/IF ANY HEADLINES MAY BE NEEDED. EARLY AFTERNOON ANALYSIS PLACES MUCH OF NORTHERN MICHIGAN ON THE BACKSIDE OF LOW LEVEL RIDGE AXIS EXTENDING FROM THE MID MISS VALLEY UP THROUGH EASTERN ONTARIO...WHILE ALOFT...WEAK SHORTWAVE RIDGING BUILDING ACROSS THE REGION IN ADVANCE SHORTWAVE ENERGY DROPPING THROUGH THE NORTHERN HIGH PLAINS. OVERALL LOW LEVEL FLOW REGIME HAS BEEN IN TRANSIT THROUGH THE DAY...STARTING NORTH/NORTHWEST AND ENDING UP MORE WEST/SOUTHWEST AS OF 19Z...WITH A CORRESPONDING SHIFT IN LAKE EFFECT SNOW SHOWERS TOWARD THE WSW FAVORED LOCATIONS. DESPITE RATHER SCANT 900-700MB MOISTURE INITIALLY...LATEST RUC/SATELLITE ANALYSIS SHOWS AN UPTICK IN BOUNDARY LAYER RH GIVEN INCREASINGLY LONG FETCH ACROSS LAKE MICHIGAN. SNOWFALL AMOUNTS THROUGH THE DAY HAVE BEEN RATHER IMPRESSIVE IN A FEW SPOTS...NAMELY OWING TO PRONOUNCED STUBBORN LOW LEVEL CONVERGENCE AS A WEAK WARM FRONT SNUCK ITS WAY NORTH THROUGH THE DAY. BIGGEST WINNERS SO FAR - CHARLEVOIX AND EMMET COUNTIES...WHERE SEVERAL REPORTS OF 3 TO AS MUCH AS LOCALLY 5 INCHES HAVE BEEN NOTED...VERY MUCH IN LINE WITH LATEST KAPX RADAR STORM TOTAL SNOW GRAPHICS. FOR TONIGHT...OVERALL PATTERN PROGGED TO CHANGE VERY LITTLE AS PERSISTENT WEST TO SOUTHWESTERLY FLOW REMAINS INTACT AHEAD OF APPROACHING LOW/MID LEVEL TROUGH. PLENTY OF OVER-LAKE INSTABILITY TO WORK WITH (OBVIOUSLY GIVEN ONGOING SNOWS)...WITH H85 TEMPS PROGGED TO "WARM" JUST SLIGHTLY TO AROUND -10C BY 12Z TOMORROW. 900-700MB RH ALSO QUITE CONDUCIVE FOR LES...WITH VALUES ON THE RISE TO 80 PERCENT OR BETTER OVERNIGHT PER CONTINUED LONG FETCH UP LAKE MICHIGAN. DIFFICULT TO FIND ANY REASON WHY SNOWS WON/T CONTINUE THROUGH MUCH OF THE NIGHT AS WEST/SOUTHWEST FLOW HOLDS STATUS QUO...AND INCREASING GRADIENT ACTS TO PREVENT ANY LAND BREEZES THAT COULD POTENTIALLY TRY TO SHOVE ANY SNOW BANDS FARTHER OFFSHORE. USING THE 15Z SREF POP MEAN AS GUIDANCE...WILL HANG THE HIGHEST POPS ACROSS EMMET AND SOUTHERN MACKINAC COUNTIES (I.E. W/SW FLOW AREAS)...AND WILL RUN WITH A WARNING ACROSS EMMET (GIVEN ALREADY SNOWY CONDITIONS THIS AFTERNOON) AND AN ADVISORY FOR MACKINAC (WITH A HIGHER CRITERIA FOR WARNING). HEADING INTO TOMORROW...UPPER WAVE PROGGED TO SWING THROUGH THE REGION BETWEEN 15Z AND 21Z...WITH AXIS OF DECENT 700-500MB -DIVQ AND MUCH DEEPER PLUME OF MOISTURE (1000-500MB RH INCREASES TO BETTER THAN 90 PERCENT) ANNOUNCING THE LIKELIHOOD OF A SYNOPTIC COMPONENT TO THE EVENT. CONTINUED WEST/SOUTHWEST LOW LEVEL FLOW REGIME SHOULD EASILY CONTRIBUTE TO ENHANCEMENT ACROSS THE STRAITS REGION...HOWEVER WILL BE DEALING WITH SOME POSSIBLE PTYPE ISSUES ALONG THE IMMEDIATE COAST GIVEN LONG PERIOD OF ONSHORE FLOW...WITH FORECAST RAOBS INDICATING FREEZING LEVELS ABOUT 1500 FT AGL. SOME QUESTION WHETHER THIS WILL BE SUFFICIENT FOR MELTING...AND PROBABLY DEPENDENT ON INTENSITY OF PRECIP. HOWEVER...FOR SIMPLICITY...WILL HOLD PRECIP ALL SNOW. OUTSIDE OF THE LAKE ENHANCEMENT...OVERALL INCREASING SYNOPTIC SUPPORT SHOULD BE SUFFICIENT TO GENERATE SOME LIGHT SNOW FROM WEST TO EAST AS -DIVQ AXIS ADVANCES ACROSS NORTHERN MICHIGAN...BUT DOUBTFUL OF MUCH IN THE WAY OF ACCUMULATION GIVEN EXPECTED HIGHS IN THE LOWER/MIDDLE 30S UNDER INCREASING LOW LEVEL WARM ADVECTION AND OVERALL WEAK FORCING. ON THE MARINE SIDE...INCREASINGLY GUSTY WINDS AND BUILDING WAVES EXPECTED ON THE LAKE MICHIGAN SIDE LATE TONIGHT AND ESPECIALLY TOMORROW MORNING AS GRADIENT TIGHTENS...WITH WINDS AT THE TOP OF THE INSTABILITY-MIXED LAYER RUNNING ABOUT 35-40 KNOTS. COUPLED WITH COASTAL CONVERGENCE SHOULD EASILY SEE GUSTS IN THE GALE RANGE...WITH GALE CONDITIONS SPREADING TO OTHER NEARSHORE AREAS BY EARLY AFTERNOON AS CORE OF STRONGER 900-850MB WINDS SPREADS EAST. LAWRENCE SATURDAY NIGHT INTO SUNDAY...SOUTHWEST FLOW LAKE EFFECT IS EXPECTED TO WIND DOWN SATURDAY NIGHT AS THE SHORTWAVE TROUGH MOVES EAST OF THE REGION. 850-700MB RH FALLS FROM 55-65 PCT AT 00Z SUN TO 45-55 PCT BY 12Z AND INVERSION HEIGHTS LOWER FROM AROUND 6KFT TO ABOUT 3KFT OVER THAT SAME TIME PERIOD. THIS ALL POINTS TO A DIMINISHING TREND OF LES ACTIVITY WITH MOST ACCUMULATIONS ARRIVING DURING THE EVENING AND WILL GO UP TO A HALF INCH OVER SOUTHERN MACKINAC AND NORTHERN EMMET COUNTIES. MID-LEVEL DRY AIR WILL CONTINUE TO POUR INTO THE AREA ON SUNDAY AS 850MB TEMPS MODERATE BETWEEN -3C TO -6C IN THE MORNING TO NEAR 0C BY EARLY IN THE EVENING. BELIEVE ANY LINGERING LOW LEVEL INSTABILITY WILL BE TOO SHALLOW FOR ANY LES ACTIVITY AND WILL KEEP SNOW CHANCES OUT OF THE FORECAST. MOISTURE ALONG THE LOW LEVEL BAROCLINIC ZONE WILL MOVE NE INTO ONTARIO AS WILL MID-UPPER LEVEL MOISTURE ALONG THE SOUTHERN FRINGES OF THE JET STREAM. SO WITH THE DEPARTING MOISTURE ACROSS THE NORTHERN CWA...LOOKS LIKE SOME SUNSHINE WILL BE HAD ON SUNDAY WITH HIGHS RANGING FROM THE UPPER 30S NORTH TO MID 40S SOUTH. SUNDAY NIGHT INTO MONDAY...SURFACE LOW PRESSURE AHEAD OF A MID- LEVEL WAVE OVER THE NORTHERN PLAINS WILL TRACK ALONG ITS WARM FRONT ACROSS SOUTHERN ONTARIO. AHEAD OF THE SURFACE LOW...SW WINDS WILL BRING RELATIVELY WARM AIR (850MB TEMPS BETWEEN -3C AND 0C) INTO MICHIGAN...WHICH WILL LEAD TO LOWS IN THE UPPER 20S TO MIDDLE 30S. DRY AIR OVER THE AREA SUNDAY NIGHT WILL EVENTUALLY LOSE OUT TO INCREASING MOISTURE AHEAD OF A NE MOVING SURFACE LOW OUT OF THE SOUTHERN PLAINS...WHICH GETS PICKED UP BY THE AFOREMENTIONED PACIFIC WAVE. THIS LOW WILL TRAVEL INTO THE LOWER OHIO RIVER VALLEY BY MIDDAY TO CENTRAL OHIO BY 00Z TUE. NORTHERN PERIPHERY OF THE DEFORMATION ZONE ON THE NW SIDE OF THE LOW STILL LOOKS TO CLIP COUNTIES NEAR SAGINAW BAY. STILL HARD TO SAY IF PRECIP WILL MAKE HERE SINCE INITIAL DRY AIRMASS WILL NEED TO BE OVERCOME. WILL TAKE OUT PRECIP CHANCES FOR THE MORNING DUE TO THIS REASON BUT WILL LEAVE A LOW CHANCE OF RAIN FOR THE AFTERNOON GIVEN 850MB TEMPS AROUND 0C AND SURFACE TEMPS AROUND 40F. PASSAGE OF AN 850MB TROUGH DURING THE AFTERNOON WILL HELP SWITCH THE WINDS TO THE NW AND ADVECT IN COOLER AIR...BUT NOT COOL ENOUGH FOR LAKE EFFECT PRECIP TO BE GENERATED. HIGHS WILL BE IN THE UPPER 30S TO LOW 40S. TUESDAY THROUGH FRIDAY...MODELS HAVE A LITTLE BETTER HANDLE ON THE NEXT SW LOW DUE TO PASS ACROSS THE OHIO VALLEY ON MONDAY AND INTO THE EASTERN GREAT LAKES ON TUESDAY...BUT STILL HAVE THEIR DIFFERENCES...SPECIFICALLY WITH THE SPEED OF THE SYSTEM. BEYOND TUESDAY...LOW CONFIDENCE EXISTS WITH LOW PRESSURE DEVELOPMENT MID TO LATE NEXT WEEK. PUT HIGHER FAITH IN THE ENSEMBLES THAN ANY ONE PARTICULAR MODEL RUN. TUESDAY...LOW PRESSURE WILL MOVE FROM THE OHIO RIVER VALLEY NE INTO NEW ENGLAND. THE 06Z GFS IS ON THE NORTHERN EDGE OF ENSEMBLE MEMBERS WHILE THE 00Z ECMWF IS ON THE QUICKER SIDE...SO TRIED TO TAKE A MORE CONSENSUS TRACK. THIS WOULD PLACE THE SOUTHEAST CWA ON THE EDGE OF THE DEFORMATION ZONE MONDAY NIGHT. AN INVERTED TROUGH WILL EMANATE FROM THIS LOW AND MOVE ACROSS THE CWA AS THE SURFACE LOW PASSES TO OUR SE. WINDS BEHIND THIS TROUGH WILL SWITCH TO THE NW AND BRING IN COLDER AIR WHICH HAS THE CHANCE TO START UP LAKE EFFECT PROCESSES. 06Z GFS IS ON THE COLDER EDGE OF GUIDANCE AND WILL TEMPER EXPECTATIONS ON HOW QUICK THE COLDER AIR MOVES IN...ESPECIALLY SINCE 00Z GFS ENSEMBLE HAS SLOWED THE PROGRESSION OF THE COLDER AIR INTO THE AREA. BUT WITH THE GENERAL LOW LEVEL CYCLONIC FLOW...AND QUESTION MARKS WITH LAKE EFFECT PROCESSES...WILL LEAVE A GENERAL LOW CHANCE POP MONDAY NIGHT. MEANWHILE...NORTHERN STREAM ENERGY ROTATING AROUND THE POLAR VORTEX WILL SKIRT BY TO THE NORTH WITHOUT MUCH IMPACT. ALTHOUGH THE CORE OF THE COLD AIR WILL SKIRT BY TO THE NORTH...COLD AIR ADVECTION WILL CONTINUE DURING THE DAY AS 850MB TEMPS FALL INTO THE LOWER TEENS. HOWEVER...VERY DRY AIR WILL POUR INTO THE NORTHERN GREAT LAKES BEHIND THE SURFACE LOW...AND DO NOT EXPECT A LARGE LAKE EFFECT EVENT. HIGHS WILL BE IN THE MIDDLE TO UPPER 30S. WEDNESDAY...HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE STATE. ANY LIGHT LAKE EFFECT WILL CONTINUE INTO TUESDAY NIGHT...WHILE MID-HIGH CLOUDS WILL STREAM ACROSS THE AREA WITH SW ALOFT. DRY LOW LEVELS WITH THE SURFACE RIDGE AXIS PRESENT WILL TRY TO KEEP THE AREA PRECIP FREE DESPITE 850MB TEMPS AROUND -10C. SO WILL GO WITH A DRY BUT MOSTLY CLOUDY DAY WITH HIGHS IN THE LOWER TO MIDDLE 30S. THURSDAY THROUGH FRIDAY...CONFIDENCE LOW DURING THIS PERIOD...ALL STEMMING FROM THE STRENGTH OF SURFACE LOW AS THE NEXT PACIFIC WAVE EMERGES FROM THE ROCKIES. 06Z GFS/00Z ECMWF LEAVE THE DOOR OPEN FOR A STRONGER SURFACE WAVE THAT WOULD PASS ACROSS THE CENTRAL GREAT LAKES WEDNESDAY NIGHT...BUT THEIR SOLUTIONS DO NOT HAVE MUCH SUPPORT FROM THE GFS ENSEMBLE MEMBERS. WILL INCREASE POPS HEADING INTO THURSDAY AS SOME SORT OF SURFACE FEATURE PASSES TO THE SOUTH...THEN KEEP A CHANCE OF SNOW FOR FRIDAY FOR THE LAKE EFFECT SNOW BELTS AS COLDER AIR WRAPS IN BEHIND ANY SYSTEM. MPC && .AVIATION... /ISSUED 1245 PM EST FRI NOV 23 2007/ A VARIETY OF WEATHER CONDITIONS ACROSS THE REGION EXPECTED THROUGH TONIGHT...WITH KPLN LIKELY TO EXPERIENCE THE WORST OF THE WEATHER. ONGOING LAKE EFFECT SNOW SHOWERS WILL SHIFT AWAY FROM KTVC THROUGH THE AFTERNOON...BUT BECOME MORE FOCUSED ON KPLN BY LATE AFTERNOON AND THROUGH TONIGHT. MEANWHILE...DO NOT EXPECT MUCH OF ANYTHING AROUND KAPN...WITH JUST AN INCREASE IN MID/HIGH CLOUDS (MAYBE A LITTLE STRATOCU EARLY TOO) THROUGH THE NIGHT IN ADVANCE OF NEXT SHORTWAVE DROPPING THROUGH THE NORTHERN HIGH PLAINS. WINDS WILL BE ON THE INCREASE THROUGH THE NIGHT...AND ESPECIALLY TOMORROW MORNING AS GRADIENT TIGHTENS IN ADVANCE OF LOW PRESSURE OVER SOUTHERN ONTARIO...WITH GUSTS OF 20 TO 25 KNOTS POSSIBLE BY 12-15Z. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST SATURDAY FOR MIZ015. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SATURDAY FOR MIZ016. LM...GALE WARNING FROM 7 AM SATURDAY TO 11 AM EST SUNDAY FOR LMZ323- 341-342-344>346. LH...GALE WARNING FROM 7 AM SATURDAY TO 11 AM EST SUNDAY FOR LHZ345>349. LS...GALE WARNING FROM 7 AM SATURDAY TO 5 AM EST SUNDAY FOR LSZ321- 322. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1230 PM EST FRI NOV 23 2007 UPDATED FOR 18Z TAF DISCUSSION .SYNOPSIS (ISSUED AT 308 AM EST)... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED HIGHLY AMPLIFIED FLOW ACROSS NORTH AMERICA...WITH RIDGING EXTENDING FROM JUST ALONG THE WEST COAST OF THE U.S. INTO THE YUKON AND TROUGHING COVERING MUCH OF THE REST OF CANADA INTO THE SOUTHERN THIRD OF THE U.S.. WITHIN THE TROUGH...THERE ARE THREE MAIN SHRTWVS TO NOTE. THE FIRST SHRTWV LOCATED OVER CENTRAL MANITOBA CAN BE SEEN ON IR IMAGERY WITH HIGH CLOUDS OVER NW ONTARIO AT THE SURFACE BY A COLD FRONT OVER CENTRAL MANITOBA. WARM ADVECTION SOUTH OF THIS SHRTWV IS SUPPORTING A BAND OF STRATUS MOVING ACROSS NORTHERN MN...WHICH HAS HAD SOME FLURRIES ASSOCIATED WITH IT. THE SECOND SHRTWV IS COMING DOWN THROUGH THE NORTHWEST TERRITORIES ON THE EAST SIDE OF THE RIDGE. THE LAST SHRTWV IS UP IN THE NUNAVUT REGION ASSOCIATED WITH THE POLAR VORTEX. CLOSER TO HOME...A 1028MB SURFACE RIDGE HAS DROPPED SE INTO UPPER MI. DRY AIR SEEN ON THE 00Z INL SOUNDING AND CLEAR SKIES ASSOCIATED WITH THE HIGH HAS ALLOWED INLAND TEMPERATURES TO DROP TO 1 ABOVE F AT WAKEFIELD AND IN LAND O LAKES (THE CHAMPION AREA IS PROBABLY JUST AS COLD GIVEN THAT WE ARE 7 ABOVE HERE). A FEW LAKE EFFECT SNOW SHOWERS ARE STILL MANAGING TO PERSIST OVER THE KEWEENAW PENINSULA AND EAST OF MARQUETTE...DESPITE THE DRY AIR. LOOK LIKE THE LAKE EFFECT IS BEING MAINTAINED MOSTLY BY LAND BREEZE CONVERGENCE MECHANISMS...AND WITH LIGHT FLOW...MORE LAKE MOISTENING CAN TAKE PLACE. IN FACT...CMX DID GO DOWN TO A 1/2SM A COUPLE OF HOURS AGO. && .DISCUSSION (ISSUED AT 308 AM EST)... MAIN FORECAST CONCERN IS POSITION OF LAKE EFFECT BAND OVER WESTERN LAKE SUPERIOR TODAY THROUGH SATURDAY. TODAY...SHRTWV OVER MANITOBA WILL DROP SE INTO NORTHERN ONTARIO BY 00Z...BRINGING THE SURFACE COLD FRONT DOWN INTO NORTHERN MN. SW FLOW AHEAD OF THE FRONT SHOULD BRING SOME WARMER AIR INTO THE CWA... THOUGH WITH 00Z RAOBS SHOWING 850MB TEMPS AS COLD AS -12C AT MPX...BIS AND ABR...NOT A WHOLE LOT OF WARMING WILL TAKE PLACE. IN FACT...THE NAM/GFS ONLY SHOW 850MB TEMPS WARMING TO ABOUT -9 TO -11C BY 21Z WHICH WOULD BE AN INCREASE OF 2-3C FROM CURRENT. INITIAL SURGE OF WARM ADVECTION OVER NORTHERN MN LOOKS TO ENTER WESTERN LAKE SUPERIOR AND THE WESTERN U.P. THIS MORNING...THEN CROSSES EASTERN LAKE SUPERIOR DURING THE AFTERNOON. BEST FORCING FOR -SN IS MAINLY OVER LAKE SUPERIOR AND THE KEWEENAW PENINSULA GIVEN THE TRACK OF THE SHRTWV...HOWEVER SOME MID CLOUDS ARE LIKELY TO CROSS THE REST OF THE CWA. GIVEN THE COLD 850MB TEMPS...THE OTHER ITEM TO WATCH IS LAKE EFFECT. SINCE LAKE EFFECT BANDS STILL PERSIST RIGHT NOW OVER WESTERN LAKE SUPERIOR...THEY SHOULD REORIENT THEMSELVES WITH THE SW FLOW. RIGHT NOW IT APPEARS THEY SHOULD STAY OFFSHORE OF THE KEWEENAW PENINSULA...WITH THE STRONGEST CONVERGENCE FOCUSED BETWEEN KEWEENAW COUNTY AND ISLE ROYALE. WILL MAINTAIN SCATTERED SNOW SHOWERS FOR THE MORNING UP IN THE KEWEENAW AS WE WAIT FOR THE WINDS TO BACK SW...BUT IN THE AFTERNOON...ANY LAKE EFFECT SNOW SHOULD STAY OFFSHORE. TEMPS TODAY SHOULD REMAIN FAIRLY COOL OVER THE INTERIOR WEST HALF...BUT PROBABLY REACH AT OR ABOVE FREEZING ALONG THE LAKE SUPERIOR SHORELINE (DOWNSLOPING) AND OVER THE EAST WITH FLOW OFF LAKE MICHIGAN. TONIGHT...SHRTWV OVER THE YUKON IS PROGGED TO DROP DOWN INTO MANITOBA AND CONNECT WITH THE SHRTWV OVER THE NUNAVUT REGION... BRINGING YET ANOTHER COLD FRONT SOUTHWARD INTO NW ONTARIO. SW FLOW AHEAD OF THIS FRONT...ALONG WITH THE SHRTWV TODAY MOVING INTO NORTHERN ONTARIO HEADING OFF INTO QUEBEC...SHOULD RESULT IN A SLOW EASTWARD MOVEMENT OF THE COLD FRONT OVER NORTHERN MN. THERE IS SOME QUESTION WHETHER OR NOT IT WILL MAKE INTO THE KEWEENAW PENINSULA BEFORE 12Z. IF IT MOVES INTO THE KEWEENAW PENINSULA AS SUGGESTED BY OUR LOCAL WRF-ARW RUN...THEN THERE COULD BE A PERIOD OF DECENT LAKE EFFECT SNOW DUE TO CONVERGENCE ALONG THE FRONTAL BOUNDARY. HOWEVER...THE GFS AND NAM WANT TO KEEP THE FRONT TO THE WEST...WHICH RESULTS IN GENERAL SW FLOW...THUS HOLDING ANY LES CONVERGENT BAND OFFSHORE. PREVIOUS FORECAST HAD LIKELY SNOW SHOWERS AFTER MIDNIGHT OVER KEWEENAW COUNTY...AND HAVE DECIDED TO LEAVE IT ALONE UNTIL A CLEARER PICTURE IS PRESENT TO EITHER UPGRADE OR DOWNGRADE POPS. OVER THE REST OF THE CWA...MODELS DEPICT ANOTHER SURGE OF LOW TO MID-LEVEL MOISTURE MOVING ACROSS THE CWA IN SW FLOW ALOFT AHEAD OF UPPER TROUGHING CROSSING MN. THE GFS DEPICTS SOME LIGHT QPF WITH THIS MOISTURE GIVEN RELATIVELY WEAK DPVA FORCING. WE COULD BE DEALING WITH EITHER SOME LIGHT SNOW SHOWERS OR FLURRIES... BUT GIVEN THE WEAK FORCING...NO MORE THAN 20 POPS ARE WARRANTED. WITH A SW BREEZE AND CLOUD COVER...BROUGHT TEMPS UP A FEW DEGREES FROM THE PREVIOUS FORECAST. SATURDAY...THE WESTERN NORTH AMERICA RIDGE IS PROGGED TO BREAK DOWN DURING THIS PERIOD...CAUSING THE FLOW TO TURN MORE ZONAL ACROSS THE NORTHERN U.S.. THUS...ALTHOUGH THE SHRTWV OVER MANITOBA IS FAIRLY STRONG...IT WILL GET SHUNTED TO THE EAST INTO NORTHERN ONTARIO WITH THE POLAR VORTEX ONLY MAKING IT AS FAR SOUTH AS CHURCHILL MANITOBA. HOWEVER...THE FLOW TURNING WESTERLY ALOFT SHOULD HELP PROPEL THE COLD FRONT NEAR OR OVER WESTERN LAKE SUPERIOR ACROSS THE CWA. THEREFORE LAKE EFFECT SNOW SHOWERS ARE EXPECTED FOR THE KEWEENAW PENINSULA...MOST LIKELY HEAVIEST IN THE MORNING WITH CONVERGENCE ALONG THE COLD FRONT. ANOTHER SPOT OF INTEREST FOR LAKE EFFECT SNOW IS THE EASTERN PORTIONS OF LUCE AND SCHOOLCRAFT COUNTIES. RIGHT NOW THE WINDS APPEAR TOO SW TO IMPACT THESE AREAS...BUT SOMETHING TO WATCH. FOR THE REST OF THE CWA...SOME LIGHT SNOW IS POSSIBLE IN THE MORNING AS MENTIONED IN THE TONIGHT DISCUSSION AS THE UPPER TROUGH OVER MN CROSSES THE CWA. COOL 850MB TEMPS REMAINING OVER THE AREA (-9 TO -10C) COMBINED WITH MORNING CLOUD COVER SHOULD KEEP SURFACE TEMPS COOL BUT PROBABLY SIMILAR TO HIGHS OF TODAY. SATURDAY NIGHT INTO SUNDAY...ANOTHER SHRTWV TROUGH IS SHOWN TO DROP SOUTH THROUGH BRITISH COLUMBIA SAT NIGHT...DEVELOPING LOW PRESSURE OVER CENTRAL SASKATCHEWAN BY 12Z SUNDAY. AS THE TROUGH MOVES SOUTH INTO MONTANA IN RESPONSE OT A MUCH STRONGER TROUGH DROPPING INTO NORTHERN ALBERTA ON SUNDAY...THE LOW PRESSURE AREA GETS SHUNTED SE TO SE MANITOBA BY 00Z MON. SW FLOW AHEAD OF THIS LOW WILL HELP TO BRING SOME WARMER AIR INTO THE CWA ON SUNDAY...WITH 850MB TEMPS PROGGED TO CLIMB TO 0C BY 00Z MONDAY. BEFORE THIS HAPPENS...THERE IS ONE CONCERN FOR SATURDAY NIGHT. ALTHOUGH THE UPPER TROUGH CROSSING THE AREA ON SATURDAY WILL BE HEADING OFF TOWARDS QUEBEC...THE COLD FRONT ASSOCIATED WITH IT IS EXPECTED TO MOVE SOUTH INTO THE KEWEENAW PENINSULA. MAY HAVE TO WATCH THIS AS THERE LOOKS TO BE SOME DECENT CONVERGENCE ALONG THE FRONT...ALONG WITH SOME MID-LEVEL MOISTURE AND WEAK LIFT OVERHEAD THAT COULD PROVIDE SOME ENHANCEMENT. THIS ZONE OF MID-LEVEL MOISTURE...MOSTLY CAUSED BY ISENTROPIC LIFTING IN THE WARM ADVECTION PATTERN THAT DEVELOPS AHEAD OF THE APPROACHING LOW...WILL REMAIN OVER THE CWA FOR MUCH OF SATURDAY NIGHT INTO SUNDAY MORNING. THIS CLOUD DECK WILL HELP TO HOLD READINGS UP SATURDAY NIGHT...BUT MAY PREVENT OUR HIGHS FROM GETTING AS WARM AS THEY COULD ON SUNDAY. TRIMMED TEMPS BACK A DEGREE OR TWO ON SUNDAY TO ACCOUNT FOR THESE CLOUDS. SUNDAY NIGHT INTO MONDAY...STRONG UPPER TROUGH OVER NORTHERN ALBERTA IS PROGGED TO CONTINUE DROPPING SOUTH...BUT STRONG PACIFIC FLOW REDEVELOPING ON MONDAY WILL ALSO CAUSE MUCH OF THIS UPPER TROUGH TO GET SHUNTED EAST. AT 00Z TUE...ALL THE MODELS DEPICT AN UPPER LOW/TROUGH SITUATED NEAR THE MANITOBA/NORTHERN ONTARIO BORDER. WITH THE FLOW STAYING FAIRLY PROGRESSIVE...THE LOW THAT WAS OVER SE MANITOBA AT 00Z MON SHOULD MOVE ACROSS NORTHERN ONTARIO ON MONDAY...DRAGGING A COLD FRONT ACROSS THE AREA. THE SYSTEM LOOKS QUITE DRY...WITH MOST OF THE MOISTURE TIED UP WITH A SOUTHERN STREAM SYSTEM MOVING THROUGH THE OHIO VALLEY. THUS...THE ONLY WAY IT LOOKS LIKE WE CAN GET PCPN WOULD BE FROM LAKE EFFECT...WITH THE ECMWF SHOWING 850MB TEMPS DROPPING TO -8 TO -10C BY 00Z TUE. HOWEVER...GIVEN TIME OF DAY AND LACK OF ANY LAKE EFFECT TO BEGIN WITH...GENERATING LAKE EFFECT MIGHT BE DIFFICULT. THEREFORE...HAVE LOWERED POPS TO 20 AND ONLY PUT THEM IN THE AFTERNOON FOR NW FLOW AREAS. DESPITE MOSTLY CLEAR SKIES FOR SUNDAY NIGHT...A WARMER AIRMASS MOVING IN AND SOMEWHAT OF A SW BREEZE SHOULD HELP HOLD READINGS UP. ON MONDAY...SOME SUN DURING THE MORNING SHOULD HELP BOOST READINGS TO HIGHS SIMILAR TO THOSE ON SUNDAY...WITH PERHAPS A STEADY OR SLOWLY FALLING TEMPERATURE TREND IN THE AFTERNOON WITH THE COLD FRONTAL PASSAGE. BEYOND MONDAY...THERE REMAINS CONSIDERABLE UNCERTAINTY ON ANY COLD SHOT OF AIR COMING INTO THE AREA FOR MONDAY NIGHT AND TUESDAY. 00Z GFS STILL WANTS TO BRING THE UPPER TROUGH ON TUESDAY ACROSS THE CWA...WHICH ALLOWS 850MB TEMPS TO FALL TO -15 TO -19C BY 00Z. HOWEVER...THE 00Z ECMWF KEEPS THAT UPPER TROUGH PROGRESSIVE...MOVING IT INTO QUEBEC BY 00Z WED. ALSO...THE 00Z ECMWF DEPICTS A LOW PRESSURE SYSTEM DEVELOPING IN THE PLAINS ON TUE...AND FRONTOGENESIS NORTH OF THIS LOW COULD RESULT IN SOME LIGHT SNOW IMPACTING THE CWA BY TUESDAY EVENING. 850MB TEMPS IN THE 00Z ECMWF ARE MUCH WARMER...FROM -4C NEAR MNM TO -12C OVER NORTHERN LAKE SUPERIOR. GIVEN THIS DIFFERENCE AND CHANGE FROM PREVIOUS RUNS...WILL NOT MODIFY THE FORECAST MUCH BEYOND MONDAY. HOWEVER...GIVEN WHAT LOOKS TO BE STRONGER PACIFIC FLOW ON MONDAY NOW...THE ECMWF SOLUTION MAY NOT BE TOO FAR-FETCHED. IF THE ECMWF DOES PAN OUT...THAT LOW PRESSURE SYSTEM IS SHOWN TO MOVE UP INTO THE CWA ON WED...WHICH COULD PROVIDE FOR SOME DECENT SYNOPTIC SNOW...PARTICULARLY ON THE NORTH AND NORTHWEST SIDE OF THE LOW TRACK. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL AT KSAW THRU THIS FCST PERIOD. THERE MIGHT BE A FEW FLURRIES LATE IN THE NIGHT AND SAT MORNING...BUT NO VIS RESTRICTION IS EXPECTED. AT KCMX...VFR CONDITIONS WILL PREVAIL WHILE AWAITING THE EVOLUTION OF LAKE EFFECT -SHSN OVER WRN LAKE SUPERIOR. IT IS VERY UNCERTAIN WHETHER THE WINDS WILL VEER WRLY ENOUGH LATE TONIGHT OR SAT MORNING TO BRING WHAT COULD BE A FAIRLY SIGNIFICANT DOMINANT SNOW BAND ONSHORE AS FAR S AS KCMX. WITH LOW CONFIDENCE...TENTATIVELY INCLUDED MVFR VIS IN -SHSN MID MORNING SAT BASED ON SUGGESTION FROM SOME OF THE HIGHER RESOLUTION FORECAST MODELS THAT WINDS WILL VEER ENOUGH TO THE W. CONDITIONS COULD REMAIN VFR OR DROP TO IFR DEPENDING ON VERY SUBTLE CHANGES IN WIND DIRECTION. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FCST CONCERN IS THE POTENTIAL FOR GALES OVER THE WEEKEND. OF GREATEST CONCERN IS THE WINDS SATURDAY AFTERNOON AND EVENING..BASICALLY 21Z FOR THE ENTIRE LAKE TO AROUND 06Z SUNDAY ACROSS THE EAST. FREQUENT WIND GUSTS TO NEAR GALE CRITERIA STILL SEEM REALISTIC AS THE TROUGH/COLD FRONT SWINGS ACROSS THE AREA. SUNDAY IS BECOMING LESS OF A CONCERN...AND HAVE DECREASED WINDS AS A RESULT. STILL...SOME DISCREPANCIES REMAIN WITH THE POSITIONING AND STRENGTH OF THIS NEXT LOW. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...ROLFSON MARINE...KF mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 640 AM EST FRI NOV 23 2007 UPDATED FOR 12Z TAF DISCUSSION .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED HIGHLY AMPLIFIED FLOW ACROSS NORTH AMERICA...WITH RIDGING EXTENDING FROM JUST ALONG THE WEST COAST OF THE U.S. INTO THE YUKON AND TROUGHING COVERING MUCH OF THE REST OF CANADA INTO THE SOUTHERN THIRD OF THE U.S.. WITHIN THE TROUGH...THERE ARE THREE MAIN SHRTWVS TO NOTE. THE FIRST SHRTWV LOCATED OVER CENTRAL MANITOBA CAN BE SEEN ON IR IMAGERY WITH HIGH CLOUDS OVER NW ONTARIO AT THE SURFACE BY A COLD FRONT OVER CENTRAL MANITOBA. WARM ADVECTION SOUTH OF THIS SHRTWV IS SUPPORTING A BAND OF STRATUS MOVING ACROSS NORTHERN MN...WHICH HAS HAD SOME FLURRIES ASSOCIATED WITH IT. THE SECOND SHRTWV IS COMING DOWN THROUGH THE NORTHWEST TERRITORIES ON THE EAST SIDE OF THE RIDGE. THE LAST SHRTWV IS UP IN THE NUNAVUT REGION ASSOCIATED WITH THE POLAR VORTEX. CLOSER TO HOME...A 1028MB SURFACE RIDGE HAS DROPPED SE INTO UPPER MI. DRY AIR SEEN ON THE 00Z INL SOUNDING AND CLEAR SKIES ASSOCIATED WITH THE HIGH HAS ALLOWED INLAND TEMPERATURES TO DROP TO 1 ABOVE F AT WAKEFIELD AND IN LAND O LAKES (THE CHAMPION AREA IS PROBABLY JUST AS COLD GIVEN THAT WE ARE 7 ABOVE HERE). A FEW LAKE EFFECT SNOW SHOWERS ARE STILL MANAGING TO PERSIST OVER THE KEWEENAW PENINSULA AND EAST OF MARQUETTE...DESPITE THE DRY AIR. LOOK LIKE THE LAKE EFFECT IS BEING MAINTAINED MOSTLY BY LAND BREEZE CONVERGENCE MECHANISMS...AND WITH LIGHT FLOW...MORE LAKE MOISTENING CAN TAKE PLACE. IN FACT...CMX DID GO DOWN TO A 1/2SM A COUPLE OF HOURS AGO. && .DISCUSSION... MAIN FORECAST CONCERN IS POSITION OF LAKE EFFECT BAND OVER WESTERN LAKE SUPERIOR TODAY THROUGH SATURDAY. TODAY...SHRTWV OVER MANITOBA WILL DROP SE INTO NORTHERN ONTARIO BY 00Z...BRINGING THE SURFACE COLD FRONT DOWN INTO NORTHERN MN. SW FLOW AHEAD OF THE FRONT SHOULD BRING SOME WARMER AIR INTO THE CWA... THOUGH WITH 00Z RAOBS SHOWING 850MB TEMPS AS COLD AS -12C AT MPX...BIS AND ABR...NOT A WHOLE LOT OF WARMING WILL TAKE PLACE. IN FACT...THE NAM/GFS ONLY SHOW 850MB TEMPS WARMING TO ABOUT -9 TO -11C BY 21Z WHICH WOULD BE AN INCREASE OF 2-3C FROM CURRENT. INITIAL SURGE OF WARM ADVECTION OVER NORTHERN MN LOOKS TO ENTER WESTERN LAKE SUPERIOR AND THE WESTERN U.P. THIS MORNING...THEN CROSSES EASTERN LAKE SUPERIOR DURING THE AFTERNOON. BEST FORCING FOR -SN IS MAINLY OVER LAKE SUPERIOR AND THE KEWEENAW PENINSULA GIVEN THE TRACK OF THE SHRTWV...HOWEVER SOME MID CLOUDS ARE LIKELY TO CROSS THE REST OF THE CWA. GIVEN THE COLD 850MB TEMPS...THE OTHER ITEM TO WATCH IS LAKE EFFECT. SINCE LAKE EFFECT BANDS STILL PERSIST RIGHT NOW OVER WESTERN LAKE SUPERIOR...THEY SHOULD REORIENT THEMSELVES WITH THE SW FLOW. RIGHT NOW IT APPEARS THEY SHOULD STAY OFFSHORE OF THE KEWEENAW PENINSULA...WITH THE STRONGEST CONVERGENCE FOCUSED BETWEEN KEWEENAW COUNTY AND ISLE ROYALE. WILL MAINTAIN SCATTERED SNOW SHOWERS FOR THE MORNING UP IN THE KEWEENAW AS WE WAIT FOR THE WINDS TO BACK SW...BUT IN THE AFTERNOON...ANY LAKE EFFECT SNOW SHOULD STAY OFFSHORE. TEMPS TODAY SHOULD REMAIN FAIRLY COOL OVER THE INTERIOR WEST HALF...BUT PROBABLY REACH AT OR ABOVE FREEZING ALONG THE LAKE SUPERIOR SHORELINE (DOWNSLOPING) AND OVER THE EAST WITH FLOW OFF LAKE MICHIGAN. TONIGHT...SHRTWV OVER THE YUKON IS PROGGED TO DROP DOWN INTO MANITOBA AND CONNECT WITH THE SHRTWV OVER THE NUNAVUT REGION... BRINGING YET ANOTHER COLD FRONT SOUTHWARD INTO NW ONTARIO. SW FLOW AHEAD OF THIS FRONT...ALONG WITH THE SHRTWV TODAY MOVING INTO NORTHERN ONTARIO HEADING OFF INTO QUEBEC...SHOULD RESULT IN A SLOW EASTWARD MOVEMENT OF THE COLD FRONT OVER NORTHERN MN. THERE IS SOME QUESTION WHETHER OR NOT IT WILL MAKE INTO THE KEWEENAW PENINSULA BEFORE 12Z. IF IT MOVES INTO THE KEWEENAW PENINSULA AS SUGGESTED BY OUR LOCAL WRF-ARW RUN...THEN THERE COULD BE A PERIOD OF DECENT LAKE EFFECT SNOW DUE TO CONVERGENCE ALONG THE FRONTAL BOUNDARY. HOWEVER...THE GFS AND NAM WANT TO KEEP THE FRONT TO THE WEST...WHICH RESULTS IN GENERAL SW FLOW...THUS HOLDING ANY LES CONVERGENT BAND OFFSHORE. PREVIOUS FORECAST HAD LIKELY SNOW SHOWERS AFTER MIDNIGHT OVER KEWEENAW COUNTY...AND HAVE DECIDED TO LEAVE IT ALONE UNTIL A CLEARER PICTURE IS PRESENT TO EITHER UPGRADE OR DOWNGRADE POPS. OVER THE REST OF THE CWA...MODELS DEPICT ANOTHER SURGE OF LOW TO MID-LEVEL MOISTURE MOVING ACROSS THE CWA IN SW FLOW ALOFT AHEAD OF UPPER TROUGHING CROSSING MN. THE GFS DEPICTS SOME LIGHT QPF WITH THIS MOISTURE GIVEN RELATIVELY WEAK DPVA FORCING. WE COULD BE DEALING WITH EITHER SOME LIGHT SNOW SHOWERS OR FLURRIES... BUT GIVEN THE WEAK FORCING...NO MORE THAN 20 POPS ARE WARRANTED. WITH A SW BREEZE AND CLOUD COVER...BROUGHT TEMPS UP A FEW DEGREES FROM THE PREVIOUS FORECAST. SATURDAY...THE WESTERN NORTH AMERICA RIDGE IS PROGGED TO BREAK DOWN DURING THIS PERIOD...CAUSING THE FLOW TO TURN MORE ZONAL ACROSS THE NORTHERN U.S.. THUS...ALTHOUGH THE SHRTWV OVER MANITOBA IS FAIRLY STRONG...IT WILL GET SHUNTED TO THE EAST INTO NORTHERN ONTARIO WITH THE POLAR VORTEX ONLY MAKING IT AS FAR SOUTH AS CHURCHILL MANITOBA. HOWEVER...THE FLOW TURNING WESTERLY ALOFT SHOULD HELP PROPEL THE COLD FRONT NEAR OR OVER WESTERN LAKE SUPERIOR ACROSS THE CWA. THEREFORE LAKE EFFECT SNOW SHOWERS ARE EXPECTED FOR THE KEWEENAW PENINSULA...MOST LIKELY HEAVIEST IN THE MORNING WITH CONVERGENCE ALONG THE COLD FRONT. ANOTHER SPOT OF INTEREST FOR LAKE EFFECT SNOW IS THE EASTERN PORTIONS OF LUCE AND SCHOOLCRAFT COUNTIES. RIGHT NOW THE WINDS APPEAR TOO SW TO IMPACT THESE AREAS...BUT SOMETHING TO WATCH. FOR THE REST OF THE CWA...SOME LIGHT SNOW IS POSSIBLE IN THE MORNING AS MENTIONED IN THE TONIGHT DISCUSSION AS THE UPPER TROUGH OVER MN CROSSES THE CWA. COOL 850MB TEMPS REMAINING OVER THE AREA (-9 TO -10C) COMBINED WITH MORNING CLOUD COVER SHOULD KEEP SURFACE TEMPS COOL BUT PROBABLY SIMILAR TO HIGHS OF TODAY. SATURDAY NIGHT INTO SUNDAY...ANOTHER SHRTWV TROUGH IS SHOWN TO DROP SOUTH THROUGH BRITISH COLUMBIA SAT NIGHT...DEVELOPING LOW PRESSURE OVER CENTRAL SASKATCHEWAN BY 12Z SUNDAY. AS THE TROUGH MOVES SOUTH INTO MONTANA IN RESPONSE OT A MUCH STRONGER TROUGH DROPPING INTO NORTHERN ALBERTA ON SUNDAY...THE LOW PRESSURE AREA GETS SHUNTED SE TO SE MANITOBA BY 00Z MON. SW FLOW AHEAD OF THIS LOW WILL HELP TO BRING SOME WARMER AIR INTO THE CWA ON SUNDAY...WITH 850MB TEMPS PROGGED TO CLIMB TO 0C BY 00Z MONDAY. BEFORE THIS HAPPENS...THERE IS ONE CONCERN FOR SATURDAY NIGHT. ALTHOUGH THE UPPER TROUGH CROSSING THE AREA ON SATURDAY WILL BE HEADING OFF TOWARDS QUEBEC...THE COLD FRONT ASSOCIATED WITH IT IS EXPECTED TO MOVE SOUTH INTO THE KEWEENAW PENINSULA. MAY HAVE TO WATCH THIS AS THERE LOOKS TO BE SOME DECENT CONVERGENCE ALONG THE FRONT...ALONG WITH SOME MID-LEVEL MOISTURE AND WEAK LIFT OVERHEAD THAT COULD PROVIDE SOME ENHANCEMENT. THIS ZONE OF MID-LEVEL MOISTURE...MOSTLY CAUSED BY ISENTROPIC LIFTING IN THE WARM ADVECTION PATTERN THAT DEVELOPS AHEAD OF THE APPROACHING LOW...WILL REMAIN OVER THE CWA FOR MUCH OF SATURDAY NIGHT INTO SUNDAY MORNING. THIS CLOUD DECK WILL HELP TO HOLD READINGS UP SATURDAY NIGHT...BUT MAY PREVENT OUR HIGHS FROM GETTING AS WARM AS THEY COULD ON SUNDAY. TRIMMED TEMPS BACK A DEGREE OR TWO ON SUNDAY TO ACCOUNT FOR THESE CLOUDS. SUNDAY NIGHT INTO MONDAY...STRONG UPPER TROUGH OVER NORTHERN ALBERTA IS PROGGED TO CONTINUE DROPPING SOUTH...BUT STRONG PACIFIC FLOW REDEVELOPING ON MONDAY WILL ALSO CAUSE MUCH OF THIS UPPER TROUGH TO GET SHUNTED EAST. AT 00Z TUE...ALL THE MODELS DEPICT AN UPPER LOW/TROUGH SITUATED NEAR THE MANITOBA/NORTHERN ONTARIO BORDER. WITH THE FLOW STAYING FAIRLY PROGRESSIVE...THE LOW THAT WAS OVER SE MANITOBA AT 00Z MON SHOULD MOVE ACROSS NORTHERN ONTARIO ON MONDAY...DRAGGING A COLD FRONT ACROSS THE AREA. THE SYSTEM LOOKS QUITE DRY...WITH MOST OF THE MOISTURE TIED UP WITH A SOUTHERN STREAM SYSTEM MOVING THROUGH THE OHIO VALLEY. THUS...THE ONLY WAY IT LOOKS LIKE WE CAN GET PCPN WOULD BE FROM LAKE EFFECT...WITH THE ECMWF SHOWING 850MB TEMPS DROPPING TO -8 TO -10C BY 00Z TUE. HOWEVER...GIVEN TIME OF DAY AND LACK OF ANY LAKE EFFECT TO BEGIN WITH...GENERATING LAKE EFFECT MIGHT BE DIFFICULT. THEREFORE...HAVE LOWERED POPS TO 20 AND ONLY PUT THEM IN THE AFTERNOON FOR NW FLOW AREAS. DESPITE MOSTLY CLEAR SKIES FOR SUNDAY NIGHT...A WARMER AIRMASS MOVING IN AND SOMEWHAT OF A SW BREEZE SHOULD HELP HOLD READINGS UP. ON MONDAY...SOME SUN DURING THE MORNING SHOULD HELP BOOST READINGS TO HIGHS SIMILAR TO THOSE ON SUNDAY...WITH PERHAPS A STEADY OR SLOWLY FALLING TEMPERATURE TREND IN THE AFTERNOON WITH THE COLD FRONTAL PASSAGE. BEYOND MONDAY...THERE REMAINS CONSIDERABLE UNCERTAINTY ON ANY COLD SHOT OF AIR COMING INTO THE AREA FOR MONDAY NIGHT AND TUESDAY. 00Z GFS STILL WANTS TO BRING THE UPPER TROUGH ON TUESDAY ACROSS THE CWA...WHICH ALLOWS 850MB TEMPS TO FALL TO -15 TO -19C BY 00Z. HOWEVER...THE 00Z ECMWF KEEPS THAT UPPER TROUGH PROGRESSIVE...MOVING IT INTO QUEBEC BY 00Z WED. ALSO...THE 00Z ECMWF DEPICTS A LOW PRESSURE SYSTEM DEVELOPING IN THE PLAINS ON TUE...AND FRONTOGENESIS NORTH OF THIS LOW COULD RESULT IN SOME LIGHT SNOW IMPACTING THE CWA BY TUESDAY EVENING. 850MB TEMPS IN THE 00Z ECMWF ARE MUCH WARMER...FROM -4C NEAR MNM TO -12C OVER NORTHERN LAKE SUPERIOR. GIVEN THIS DIFFERENCE AND CHANGE FROM PREVIOUS RUNS...WILL NOT MODIFY THE FORECAST MUCH BEYOND MONDAY. HOWEVER...GIVEN WHAT LOOKS TO BE STRONGER PACIFIC FLOW ON MONDAY NOW...THE ECMWF SOLUTION MAY NOT BE TOO FAR-FETCHED. IF THE ECMWF DOES PAN OUT...THAT LOW PRESSURE SYSTEM IS SHOWN TO MOVE UP INTO THE CWA ON WED...WHICH COULD PROVIDE FOR SOME DECENT SYNOPTIC SNOW...PARTICULARLY ON THE NORTH AND NORTHWEST SIDE OF THE LOW TRACK. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... VFR CIGS AND VIS EXPECTED THROUGH THE END OF THE PERIOD. THE ONLY FLY IN THE OINTMENT TO THIS IS CMX...BOTH EARLY AND LATE. PESKY WESTERLY TO SOUTHWESTERLY FLOW CONVERGING OVER THE KEWENAW HAS BROUGHT ABOUT WIDELY VARYING VIS AND CIGS WITH SNOW SHOWERS. THIS IS EXPECTED TO WEAKEN OVER THE NEXT FEW HOURS. THE NEXT BAND OF SNOW SHOWERS MAY BE ABLE TO SLIDE FAR ENOUGH ACROSS THE KEWENAW PENINSULA TO BRING MVFR OR SLIGHTLY LOWER CONDITIONS TOWARDS THE LAST 6 TO 8 HOURS OF THE FORECAST. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FCST CONCERN IS THE POTENTIAL FOR GALES OVER THE WEEKEND. OF GREATEST CONCERN IS THE WINDS SATURDAY AFTERNOON AND EVENING..BASICALLY 21Z FOR THE ENTIRE LAKE TO AROUND 06Z SUNDAY ACROSS THE EAST. FREQUENT WIND GUSTS TO NEAR GALE CRITERIA STILL SEEM REALISTIC AS THE TROUGH/COLD FRONT SWINGS ACROSS THE AREA. SUNDAY IS BECOMING LESS OF A CONCERN...AND HAVE DECREASED WINDS AS A RESULT. STILL...SOME DISCREPANCIES REMAIN WITH THE POSITIONING AND STRENGTH OF THIS NEXT LOW. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...JLB MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 308 AM EST FRI NOV 23 2007 .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED HIGHLY AMPLIFIED FLOW ACROSS NORTH AMERICA...WITH RIDGING EXTENDING FROM JUST ALONG THE WEST COAST OF THE U.S. INTO THE YUKON AND TROUGHING COVERING MUCH OF THE REST OF CANADA INTO THE SOUTHERN THIRD OF THE U.S.. WITHIN THE TROUGH...THERE ARE THREE MAIN SHRTWVS TO NOTE. THE FIRST SHRTWV LOCATED OVER CENTRAL MANITOBA CAN BE SEEN ON IR IMAGERY WITH HIGH CLOUDS OVER NW ONTARIO AT THE SURFACE BY A COLD FRONT OVER CENTRAL MANITOBA. WARM ADVECTION SOUTH OF THIS SHRTWV IS SUPPORTING A BAND OF STRATUS MOVING ACROSS NORTHERN MN...WHICH HAS HAD SOME FLURRIES ASSOCIATED WITH IT. THE SECOND SHRTWV IS COMING DOWN THROUGH THE NORTHWEST TERRITORIES ON THE EAST SIDE OF THE RIDGE. THE LAST SHRTWV IS UP IN THE NUNAVUT REGION ASSOCIATED WITH THE POLAR VORTEX. CLOSER TO HOME...A 1028MB SURFACE RIDGE HAS DROPPED SE INTO UPPER MI. DRY AIR SEEN ON THE 00Z INL SOUNDING AND CLEAR SKIES ASSOCIATED WITH THE HIGH HAS ALLOWED INLAND TEMPERATURES TO DROP TO 1 ABOVE F AT WAKEFIELD AND IN LAND O LAKES (THE CHAMPION AREA IS PROBABLY JUST AS COLD GIVEN THAT WE ARE 7 ABOVE HERE). A FEW LAKE EFFECT SNOW SHOWERS ARE STILL MANAGING TO PERSIST OVER THE KEWEENAW PENINSULA AND EAST OF MARQUETTE...DESPITE THE DRY AIR. LOOK LIKE THE LAKE EFFECT IS BEING MAINTAINED MOSTLY BY LAND BREEZE CONVERGENCE MECHANISMS...AND WITH LIGHT FLOW...MORE LAKE MOISTENING CAN TAKE PLACE. IN FACT...CMX DID GO DOWN TO A 1/2SM A COUPLE OF HOURS AGO. && .DISCUSSION... MAIN FORECAST CONCERN IS POSITION OF LAKE EFFECT BAND OVER WESTERN LAKE SUPERIOR TODAY THROUGH SATURDAY. TODAY...SHRTWV OVER MANITOBA WILL DROP SE INTO NORTHERN ONTARIO BY 00Z...BRINGING THE SURFACE COLD FRONT DOWN INTO NORTHERN MN. SW FLOW AHEAD OF THE FRONT SHOULD BRING SOME WARMER AIR INTO THE CWA... THOUGH WITH 00Z RAOBS SHOWING 850MB TEMPS AS COLD AS -12C AT MPX...BIS AND ABR...NOT A WHOLE LOT OF WARMING WILL TAKE PLACE. IN FACT...THE NAM/GFS ONLY SHOW 850MB TEMPS WARMING TO ABOUT -9 TO -11C BY 21Z WHICH WOULD BE AN INCREASE OF 2-3C FROM CURRENT. INITIAL SURGE OF WARM ADVECTION OVER NORTHERN MN LOOKS TO ENTER WESTERN LAKE SUPERIOR AND THE WESTERN U.P. THIS MORNING...THEN CROSSES EASTERN LAKE SUPERIOR DURING THE AFTERNOON. BEST FORCING FOR -SN IS MAINLY OVER LAKE SUPERIOR AND THE KEWEENAW PENINSULA GIVEN THE TRACK OF THE SHRTWV...HOWEVER SOME MID CLOUDS ARE LIKELY TO CROSS THE REST OF THE CWA. GIVEN THE COLD 850MB TEMPS...THE OTHER ITEM TO WATCH IS LAKE EFFECT. SINCE LAKE EFFECT BANDS STILL PERSIST RIGHT NOW OVER WESTERN LAKE SUPERIOR...THEY SHOULD REORIENT THEMSELVES WITH THE SW FLOW. RIGHT NOW IT APPEARS THEY SHOULD STAY OFFSHORE OF THE KEWEENAW PENINSULA...WITH THE STRONGEST CONVERGENCE FOCUSED BETWEEN KEWEENAW COUNTY AND ISLE ROYALE. WILL MAINTAIN SCATTERED SNOW SHOWERS FOR THE MORNING UP IN THE KEWEENAW AS WE WAIT FOR THE WINDS TO BACK SW...BUT IN THE AFTERNOON...ANY LAKE EFFECT SNOW SHOULD STAY OFFSHORE. TEMPS TODAY SHOULD REMAIN FAIRLY COOL OVER THE INTERIOR WEST HALF...BUT PROBABLY REACH AT OR ABOVE FREEZING ALONG THE LAKE SUPERIOR SHORELINE (DOWNSLOPING) AND OVER THE EAST WITH FLOW OFF LAKE MICHIGAN. TONIGHT...SHRTWV OVER THE YUKON IS PROGGED TO DROP DOWN INTO MANITOBA AND CONNECT WITH THE SHRTWV OVER THE NUNAVUT REGION... BRINGING YET ANOTHER COLD FRONT SOUTHWARD INTO NW ONTARIO. SW FLOW AHEAD OF THIS FRONT...ALONG WITH THE SHRTWV TODAY MOVING INTO NORTHERN ONTARIO HEADING OFF INTO QUEBEC...SHOULD RESULT IN A SLOW EASTWARD MOVEMENT OF THE COLD FRONT OVER NORTHERN MN. THERE IS SOME QUESTION WHETHER OR NOT IT WILL MAKE INTO THE KEWEENAW PENINSULA BEFORE 12Z. IF IT MOVES INTO THE KEWEENAW PENINSULA AS SUGGESTED BY OUR LOCAL WRF-ARW RUN...THEN THERE COULD BE A PERIOD OF DECENT LAKE EFFECT SNOW DUE TO CONVERGENCE ALONG THE FRONTAL BOUNDARY. HOWEVER...THE GFS AND NAM WANT TO KEEP THE FRONT TO THE WEST...WHICH RESULTS IN GENERAL SW FLOW...THUS HOLDING ANY LES CONVERGENT BAND OFFSHORE. PREVIOUS FORECAST HAD LIKELY SNOW SHOWERS AFTER MIDNIGHT OVER KEWEENAW COUNTY...AND HAVE DECIDED TO LEAVE IT ALONE UNTIL A CLEARER PICTURE IS PRESENT TO EITHER UPGRADE OR DOWNGRADE POPS. OVER THE REST OF THE CWA...MODELS DEPICT ANOTHER SURGE OF LOW TO MID-LEVEL MOISTURE MOVING ACROSS THE CWA IN SW FLOW ALOFT AHEAD OF UPPER TROUGHING CROSSING MN. THE GFS DEPICTS SOME LIGHT QPF WITH THIS MOISTURE GIVEN RELATIVELY WEAK DPVA FORCING. WE COULD BE DEALING WITH EITHER SOME LIGHT SNOW SHOWERS OR FLURRIES... BUT GIVEN THE WEAK FORCING...NO MORE THAN 20 POPS ARE WARRANTED. WITH A SW BREEZE AND CLOUD COVER...BROUGHT TEMPS UP A FEW DEGREES FROM THE PREVIOUS FORECAST. SATURDAY...THE WESTERN NORTH AMERICA RIDGE IS PROGGED TO BREAK DOWN DURING THIS PERIOD...CAUSING THE FLOW TO TURN MORE ZONAL ACROSS THE NORTHERN U.S.. THUS...ALTHOUGH THE SHRTWV OVER MANITOBA IS FAIRLY STRONG...IT WILL GET SHUNTED TO THE EAST INTO NORTHERN ONTARIO WITH THE POLAR VORTEX ONLY MAKING IT AS FAR SOUTH AS CHURCHILL MANITOBA. HOWEVER...THE FLOW TURNING WESTERLY ALOFT SHOULD HELP PROPEL THE COLD FRONT NEAR OR OVER WESTERN LAKE SUPERIOR ACROSS THE CWA. THEREFORE LAKE EFFECT SNOW SHOWERS ARE EXPECTED FOR THE KEWEENAW PENINSULA...MOST LIKELY HEAVIEST IN THE MORNING WITH CONVERGENCE ALONG THE COLD FRONT. ANOTHER SPOT OF INTEREST FOR LAKE EFFECT SNOW IS THE EASTERN PORTIONS OF LUCE AND SCHOOLCRAFT COUNTIES. RIGHT NOW THE WINDS APPEAR TOO SW TO IMPACT THESE AREAS...BUT SOMETHING TO WATCH. FOR THE REST OF THE CWA...SOME LIGHT SNOW IS POSSIBLE IN THE MORNING AS MENTIONED IN THE TONIGHT DISCUSSION AS THE UPPER TROUGH OVER MN CROSSES THE CWA. COOL 850MB TEMPS REMAINING OVER THE AREA (-9 TO -10C) COMBINED WITH MORNING CLOUD COVER SHOULD KEEP SURFACE TEMPS COOL BUT PROBABLY SIMILAR TO HIGHS OF TODAY. SATURDAY NIGHT INTO SUNDAY...ANOTHER SHRTWV TROUGH IS SHOWN TO DROP SOUTH THROUGH BRITISH COLUMBIA SAT NIGHT...DEVELOPING LOW PRESSURE OVER CENTRAL SASKATCHEWAN BY 12Z SUNDAY. AS THE TROUGH MOVES SOUTH INTO MONTANA IN RESPONSE OT A MUCH STRONGER TROUGH DROPPING INTO NORTHERN ALBERTA ON SUNDAY...THE LOW PRESSURE AREA GETS SHUNTED SE TO SE MANITOBA BY 00Z MON. SW FLOW AHEAD OF THIS LOW WILL HELP TO BRING SOME WARMER AIR INTO THE CWA ON SUNDAY...WITH 850MB TEMPS PROGGED TO CLIMB TO 0C BY 00Z MONDAY. BEFORE THIS HAPPENS...THERE IS ONE CONCERN FOR SATURDAY NIGHT. ALTHOUGH THE UPPER TROUGH CROSSING THE AREA ON SATURDAY WILL BE HEADING OFF TOWARDS QUEBEC...THE COLD FRONT ASSOCIATED WITH IT IS EXPECTED TO MOVE SOUTH INTO THE KEWEENAW PENINSULA. MAY HAVE TO WATCH THIS AS THERE LOOKS TO BE SOME DECENT CONVERGENCE ALONG THE FRONT...ALONG WITH SOME MID-LEVEL MOISTURE AND WEAK LIFT OVERHEAD THAT COULD PROVIDE SOME ENHANCEMENT. THIS ZONE OF MID-LEVEL MOISTURE...MOSTLY CAUSED BY ISENTROPIC LIFTING IN THE WARM ADVECTION PATTERN THAT DEVELOPS AHEAD OF THE APPROACHING LOW...WILL REMAIN OVER THE CWA FOR MUCH OF SATURDAY NIGHT INTO SUNDAY MORNING. THIS CLOUD DECK WILL HELP TO HOLD READINGS UP SATURDAY NIGHT...BUT MAY PREVENT OUR HIGHS FROM GETTING AS WARM AS THEY COULD ON SUNDAY. TRIMMED TEMPS BACK A DEGREE OR TWO ON SUNDAY TO ACCOUNT FOR THESE CLOUDS. SUNDAY NIGHT INTO MONDAY...STRONG UPPER TROUGH OVER NORTHERN ALBERTA IS PROGGED TO CONTINUE DROPPING SOUTH...BUT STRONG PACIFIC FLOW REDEVELOPING ON MONDAY WILL ALSO CAUSE MUCH OF THIS UPPER TROUGH TO GET SHUNTED EAST. AT 00Z TUE...ALL THE MODELS DEPICT AN UPPER LOW/TROUGH SITUATED NEAR THE MANITOBA/NORTHERN ONTARIO BORDER. WITH THE FLOW STAYING FAIRLY PROGRESSIVE...THE LOW THAT WAS OVER SE MANITOBA AT 00Z MON SHOULD MOVE ACROSS NORTHERN ONTARIO ON MONDAY...DRAGGING A COLD FRONT ACROSS THE AREA. THE SYSTEM LOOKS QUITE DRY...WITH MOST OF THE MOISTURE TIED UP WITH A SOUTHERN STREAM SYSTEM MOVING THROUGH THE OHIO VALLEY. THUS...THE ONLY WAY IT LOOKS LIKE WE CAN GET PCPN WOULD BE FROM LAKE EFFECT...WITH THE ECMWF SHOWING 850MB TEMPS DROPPING TO -8 TO -10C BY 00Z TUE. HOWEVER...GIVEN TIME OF DAY AND LACK OF ANY LAKE EFFECT TO BEGIN WITH...GENERATING LAKE EFFECT MIGHT BE DIFFICULT. THEREFORE...HAVE LOWERED POPS TO 20 AND ONLY PUT THEM IN THE AFTERNOON FOR NW FLOW AREAS. DESPITE MOSTLY CLEAR SKIES FOR SUNDAY NIGHT...A WARMER AIRMASS MOVING IN AND SOMEWHAT OF A SW BREEZE SHOULD HELP HOLD READINGS UP. ON MONDAY...SOME SUN DURING THE MORNING SHOULD HELP BOOST READINGS TO HIGHS SIMILAR TO THOSE ON SUNDAY...WITH PERHAPS A STEADY OR SLOWLY FALLING TEMPERATURE TREND IN THE AFTERNOON WITH THE COLD FRONTAL PASSAGE. BEYOND MONDAY...THERE REMAINS CONSIDERABLE UNCERTAINTY ON ANY COLD SHOT OF AIR COMING INTO THE AREA FOR MONDAY NIGHT AND TUESDAY. 00Z GFS STILL WANTS TO BRING THE UPPER TROUGH ON TUESDAY ACROSS THE CWA...WHICH ALLOWS 850MB TEMPS TO FALL TO -15 TO -19C BY 00Z. HOWEVER...THE 00Z ECMWF KEEPS THAT UPPER TROUGH PROGRESSIVE...MOVING IT INTO QUEBEC BY 00Z WED. ALSO...THE 00Z ECMWF DEPICTS A LOW PRESSURE SYSTEM DEVELOPING IN THE PLAINS ON TUE...AND FRONTOGENESIS NORTH OF THIS LOW COULD RESULT IN SOME LIGHT SNOW IMPACTING THE CWA BY TUESDAY EVENING. 850MB TEMPS IN THE 00Z ECMWF ARE MUCH WARMER...FROM -4C NEAR MNM TO -12C OVER NORTHERN LAKE SUPERIOR. GIVEN THIS DIFFERENCE AND CHANGE FROM PREVIOUS RUNS...WILL NOT MODIFY THE FORECAST MUCH BEYOND MONDAY. HOWEVER...GIVEN WHAT LOOKS TO BE STRONGER PACIFIC FLOW ON MONDAY NOW...THE ECMWF SOLUTION MAY NOT BE TOO FAR-FETCHED. IF THE ECMWF DOES PAN OUT...THAT LOW PRESSURE SYSTEM IS SHOWN TO MOVE UP INTO THE CWA ON WED...WHICH COULD PROVIDE FOR SOME DECENT SYNOPTIC SNOW...PARTICULARLY ON THE NORTH AND NORTHWEST SIDE OF THE LOW TRACK. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... WINDS SHOULD CONTINUING BACKING TONIGHT...LEAVING CLEAR SKIES AT KSAW BUT KEEPING FLURRIES GOING AT CMX THROUGH THE NIGHT...SO LEFT PRECIP IN THE TAF THROUGH THAT TIME PERIOD. AS WINDS BECOME SW... CHANCE OF LIGHT SNOW COMES BACK INTO CMX. ALTHOUGH CMX MAY FLIRT WITH MVFR CEILINGS EARLY...CONDITIONS AT BOTH LOCATIONS SHOULD REMAIN VFR THROUGH THE PERIOD. WEST SOUTHWEST WINDS LATE FRIDAY EVENING MAY PUSH MORE LAKE EFFECT SNOW SHOWERS BACK INTO CMX. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FCST CONCERN IS THE POTENTIAL FOR GALES OVER THE WEEKEND. OF GREATEST CONCERN IS THE WINDS SATURDAY AFTERNOON AND EVENING..BASICALLY 21Z FOR THE ENTIRE LAKE TO AROUND 06Z SUNDAY ACROSS THE EAST. FREQUENT WIND GUSTS TO NEAR GALE CRITERIA STILL SEEM REALISTIC AS THE TROUGH/COLD FRONT SWINGS ACROSS THE AREA. SUNDAY IS BECOMING LESS OF A CONCERN...AND HAVE DECREASED WINDS AS A RESULT. STILL...SOME DISCREPANCIES REMAIN WITH THE POSITIONING AND STRENGTH OF THIS NEXT LOW. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...JLB MARINE...KF mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1230 AM EST FRI NOV 23 2007 UPDATED FOR 06Z AVIATION SECTION .SHORT TERM (TONIGHT AND FRI)... MAIN FCST ISSUES ARE MIN TEMPS TONIGHT AND EVOLUTION OF LES. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF DOMINATING CENTRAL NAMERICA BTWN RIDGES OVER THE W COAST AND JUST OFF THE E COAST. AT THE SFC...A LARGE AREA OF HIGH PRES WAS OVER THE WRN PLAINS WITH A RIDGE EXTENDING NE INTO ONTARIO. AIRMASS FLOWING INTO UPPER MI ON THE NRLY FLOW AHEAD OF THE RIDGE IS VERY DRY. SFC DWPTS UPWIND OF LAKE SUPERIOR ARE AROUND 0F...AND 12Z RAOBS FROM KINL/CWPL SHOWED MEAGER PRECIPITABLE WATER UNDER ONE TENTH OF AN INCH. IN THE CASE OF KINL...THAT IS 25PCT OF NORMAL FOR THIS TIME OF YEAR. THE DRY AIR HAS HAD A SIGNIFICANT NEGATIVE IMPACT ON LES DESPITE 850MB TEMPS AROUND -15C (PER EARLY AFTN TAMDAR SOUNDINGS)...YIELDING A LAKE-850MB DELTA-T AROUND 20C. NOTHING MORE THAN -SHSN/FLURRIES HAVE BEEN NOTED WITH ONE EXCEPTION. LONG FETCH COMBINED WITH PRECONDITIONING FROM LAKE NIPIGON AND LAND BREEZE CONVERGENCE INTO THUNDER BAY N OF ISLE ROYALE HAS LED TO MORE SIGNIFICANT LES STREAMING S AND IMPACTING VERY SMALL AREAS OF FAR WRN GOGEBIC/ONTONAGON COUNTIES. KIWD VCNTY HAS PICKED UP 3-4 INCHES OF SNOW TODAY. WOULDN`T BE SURPRISED IF THERE HAS BEEN LOCALLY MORE. AS THE SFC HIGH PRES RIDGE MOVES ACROSS THE UPPER LAKES REGION TONIGHT...WINDS WILL GRADUALLY BACK TO A SW DIRECTION OVER WRN UPPER MI AND TO A WNW DIRECTION OVER ERN UPPER MI BY SUNRISE. THIS WILL SHIFT LINGERING LES N AND OUT OF GOGEBIC/ONTONAGON COUNTIES. AT THIS POINT...NOT EXPECTING MUCH ACCUMULATION OVER THE WRN FCST AREA TONIGHT DUE TO SHIFTING BANDS AND LOSS OF THE LAKE NIPIGON CONNECTION. FETCH LENGTH WILL IMPROVE INTO THE KEWEENAW LATE TONIGHT WITH THE POSSIBILITY OF LAND BREEZES FOCUSING CONVERGENCE. EVEN SO...UPSTREAM DRY AIRMASS AND LOW INVERSION AROUND 4KFT SHOULD KEEP LES IN CHECK WITH ACCUMULATIONS LESS THAN 1 INCH. TO THE E...THERE SHOULD BE SOME INCREASE IN LIGHT LES AS FETCH LENGTH INCREASES IN NW FLOW. AS FOR TEMPS...THERE WILL BE A GREAT OPPORTUNITY FOR TEMPS TO CRASH TONIGHT OVER THE W AND CNTRL. HIGH PRES RIDGE ARRIVING DURING THE MIDDLE OF THE NIGHT WILL ALLOW WINDS TO GO CALM. THEN ONCE SHARP SFC BASED INVERSION DEVELOPS...RETURN FLOW WILL LIKELY NOT DEVELOP DOWN TO THE SFC UNTIL AFTER SUNRISE. MIN PRECIPITABLE WATER (ONE-TENTH OF AN INCH OR 25-35PCT OF NORMAL) PASSING OVERHEAD AT THE SAME TIME WILL ENHANCE THE COOLING POTENTIAL. LOCATIONS THAT HAVE A LIGHT SNOW COVER SHOULD SEE TEMPS TUMBLE TOWARD 0F. DECIDED TO LOWER TEMPS TO 0F AROUND THE TYPICAL COLD SPOT OF CHAMPION. WOULD NOT BE SURPRISED TO SEE THE FAR W (KIWD TOWARD BERGLAND/MARENISCO) DROP JUST AS LOW WITH THE NEW FRESH SNOW COVER. HAVE ONLY GONE 5-10F IN THAT AREA. WILL NEED TO WATCH TRENDS THERE THIS EVENING. A COUPLE OF SHORTWAVES DROPPING SE THRU SCNTRL CANADA AND THE DAKOTAS WILL BRING INCREASING CLOUDS IN WAA/ISENTROPIC ASCENT REGIME. CONDENSATION PRES DEFICITS ARE HIGH...SO IT MAY TAKE A WHILE FOR INCREASING HIGH CLOUDS TO LOWER INTO A MID CLOUD DECK DURING THE DAY. WITH 850MB TEMPS AROUND -12C OVER LAKE SUPERIOR...LES SHOULD CONTINUE ON LAKE SUPERIOR. HOWEVER...WITH SW FLOW...LES WILL BE MOSTLY BE OFFSHORE OF UPPER MI. ONLY EXCEPTION WOULD BE THE TIP OF THE KEWEENAW WHERE THERE MAY BE JUST ENOUGH OF A WRLY COMPONENT -SHSN/FLURRIES TO CLIP THAT AREA. .LONG TERM (00Z SAT ONWARD)... 500 MB TROUGHING CONTINUES TO AFFECT THE AREA FRI NIGHT AND SAT WITH NW FLOW BEFORE ZONAL UPPER LEVEL FLOW MOVES IN TO THE AREA FOR SUN. NAM SHOWING SOME 850-500 MB Q-VECTOR CONVERGENCE MOVING THROUGH FRI NIGHT AND SAT WITH SOME MOISTURE AS WELL. NAM SHOWING SOME ISENTROPIC LIFT AND MOISTURE ON I280K-I285K SURFACES IN THE MID LEVELS OF THE ATMOSPHERE FRI NIGHT. GFS SHOWS THE SAME THING ALONG WITH THE Q-VECTOR CONVERGENCE AND MOISTURE FRI NIGHT AND SAT AS WELL. MOISTURE IS IN THE MID LEVELS HOWEVER...SO WILL GO SLIGHT CHANCE POPS AFTER MIDNIGHT ACROSS THE CWA AS LOW LEVELS WILL TAKE TIME TO SATURATE EXCEPT IN THE KEWEENAW WITH LAKE EFFECT GOING. WHAT THIS WILL DO IS HELP A SOUTHWEST TO WEST ORIENTED LAKE EFFECT SNOW BAND TO GET GOING AND COULD BE ORIENTED ACROSS THE WEST HALF OF THE LAKE ACROSS THE KEWEENAW SOMEWHERE NORTH OF HOUGHTON FRI NIGHT INTO SAT. A SEEDER-FEEDER MECHANISM COULD SET UP WHICH WOULD HELP ACCUMULATIONS OUT. THE PROBLEM IS THE WIND IS WSW TO SW WHICH SHOULD KEEP THE MAJORITY OF THE HEAVY SNOW BAND OFFSHORE OF THE KEWEENAW...BUT WILL HAVE TO WATCH THIS CAREFULLY SINCE IT COULD SNOW PRETTY HEAVILY FRI NIGHT AND SAT WITH THE SEEDER-FEEDER MECHANISM IN PLACE. COULD BE ADVISORY OR CLOSE TO IT...BUT THINK A SMALL ENOUGH AREA IS AFFECTED TO NOT GO WITH ANYTHING RIGHT NOW. THIS WILL HAVE TO BE WATCHED AND IS HIGHLY DEPENDENT ON WIND DIRECTION. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST OTHERWISE. WENT CLOSE TO ADJMVR FOR TEMPERATURES. IN THE EXTENDED...GFS...CANADIAN AND ECMWF SHOW A 500 MB TROUGH ACROSS THE ROCKIES AND SOUTHERN PLAINS 00Z MON WITH ZONAL FLOW ACROSS THE NORTHERN U.S. AT THAT TIME. THE TROUGH MOVES EAST AND AFFECTS THE CWA 00Z TUE. THE TROUGH IS TO THE EAST OF THE CWA 00Z WED WITH RIDGING ACROSS THE NORTHERN PLAINS 00Z WED. RIDGING CONTINUES INTO 00Z THU AND 00Z FRI. TEMPERATURES LOOK TO BE ABOUT NORMAL TO SLIGHTLY BELOW NORMAL. WENT CLOSE TO ADJMXR FOR TEMPERATURES MOSTLY WITH A FEW MINOR TWEAKS HERE AND THERE. ALSO WENT WITH A CHANCE OF SNOW IN EVERY PERIOD BUT SUN NIGHT AND WED WITH RIDGING FOR SUN NIGHT WITH FRONT TO THE NORTH OF THE AREA AND FOR WED WITH A SFC HIGH BUILDING IN AND LIGHT WINDS. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... WINDS SHOULD CONTINUING BACKING TONIGHT...LEAVING CLEAR SKIES AT KSAW BUT KEEPING FLURRIES GOING AT CMX THROUGH THE NIGHT...SO LEFT PRECIP IN THE TAF THROUGH THAT TIME PERIOD. AS WINDS BECOME SW...CHANCE OF LIGHT SNOW COMES BACK INTO CMX. ALTHOUGH CMX MAY FLIRT WITH MVFR CEILINGS EARLY...CONDITIONS AT BOTH LOCATIONS SHOULD REMAIN VFR THROUGH THE PERIOD. WEST SOUTHWEST WINDS LATE FRIDAY EVENING MAY PUSH MORE LAKE EFFECT SNOW SHOWERS BACK INTO CMX. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FCST CONCERN IS THE POTENTIAL FOR GALES SAT/SAT EVENING AS A TROF PASSES THE AREA. TIGHTENING PRES GRADIENT WITH AIRMASS STILL UNSTABLE OVER THE LAKE SHOULD SUPPORT LOW END GALES (AT A MINIMUM FREQUENT GALE GUSTS). ANOTHER LOW PRES APPROACHING FROM THE W ON SUN COULD BOOST WINDS BACK TOWARD GALES AGAIN SUN AFTN/EVENING. HAVE ONLY INDICATED WINDS TO 30KT FOR NOW. NO GALES ARE FORESEEN FOR THE REMAINDER OF THIS FCST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...ROLFSON LONG TERM...GJM AVIATION...TAG/JLB MARINE..ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 630 PM EST THU NOV 22 2007 UPDATED FOR 00Z AVIATION SECTION .SHORT TERM (TONIGHT AND FRI)... MAIN FCST ISSUES ARE MIN TEMPS TONIGHT AND EVOLUTION OF LES. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF DOMINATING CENTRAL NAMERICA BTWN RIDGES OVER THE W COAST AND JUST OFF THE E COAST. AT THE SFC...A LARGE AREA OF HIGH PRES WAS OVER THE WRN PLAINS WITH A RIDGE EXTENDING NE INTO ONTARIO. AIRMASS FLOWING INTO UPPER MI ON THE NRLY FLOW AHEAD OF THE RIDGE IS VERY DRY. SFC DWPTS UPWIND OF LAKE SUPERIOR ARE AROUND 0F...AND 12Z RAOBS FROM KINL/CWPL SHOWED MEAGER PRECIPITABLE WATER UNDER ONE TENTH OF AN INCH. IN THE CASE OF KINL...THAT IS 25PCT OF NORMAL FOR THIS TIME OF YEAR. THE DRY AIR HAS HAD A SIGNIFICANT NEGATIVE IMPACT ON LES DESPITE 850MB TEMPS AROUND -15C (PER EARLY AFTN TAMDAR SOUNDINGS)...YIELDING A LAKE-850MB DELTA-T AROUND 20C. NOTHING MORE THAN -SHSN/FLURRIES HAVE BEEN NOTED WITH ONE EXCEPTION. LONG FETCH COMBINED WITH PRECONDITIONING FROM LAKE NIPIGON AND LAND BREEZE CONVERGENCE INTO THUNDER BAY N OF ISLE ROYALE HAS LED TO MORE SIGNIFICANT LES STREAMING S AND IMPACTING VERY SMALL AREAS OF FAR WRN GOGEBIC/ONTONAGON COUNTIES. KIWD VCNTY HAS PICKED UP 3-4 INCHES OF SNOW TODAY. WOULDN`T BE SURPRISED IF THERE HAS BEEN LOCALLY MORE. AS THE SFC HIGH PRES RIDGE MOVES ACROSS THE UPPER LAKES REGION TONIGHT...WINDS WILL GRADUALLY BACK TO A SW DIRECTION OVER WRN UPPER MI AND TO A WNW DIRECTION OVER ERN UPPER MI BY SUNRISE. THIS WILL SHIFT LINGERING LES N AND OUT OF GOGEBIC/ONTONAGON COUNTIES. AT THIS POINT...NOT EXPECTING MUCH ACCUMULATION OVER THE WRN FCST AREA TONIGHT DUE TO SHIFTING BANDS AND LOSS OF THE LAKE NIPIGON CONNECTION. FETCH LENGTH WILL IMPROVE INTO THE KEWEENAW LATE TONIGHT WITH THE POSSIBILITY OF LAND BREEZES FOCUSING CONVERGENCE. EVEN SO...UPSTREAM DRY AIRMASS AND LOW INVERSION AROUND 4KFT SHOULD KEEP LES IN CHECK WITH ACCUMULATIONS LESS THAN 1 INCH. TO THE E...THERE SHOULD BE SOME INCREASE IN LIGHT LES AS FETCH LENGTH INCREASES IN NW FLOW. AS FOR TEMPS...THERE WILL BE A GREAT OPPORTUNITY FOR TEMPS TO CRASH TONIGHT OVER THE W AND CNTRL. HIGH PRES RIDGE ARRIVING DURING THE MIDDLE OF THE NIGHT WILL ALLOW WINDS TO GO CALM. THEN ONCE SHARP SFC BASED INVERSION DEVELOPS...RETURN FLOW WILL LIKELY NOT DEVELOP DOWN TO THE SFC UNTIL AFTER SUNRISE. MIN PRECIPITABLE WATER (ONE-TENTH OF AN INCH OR 25-35PCT OF NORMAL) PASSING OVERHEAD AT THE SAME TIME WILL ENHANCE THE COOLING POTENTIAL. LOCATIONS THAT HAVE A LIGHT SNOW COVER SHOULD SEE TEMPS TUMBLE TOWARD 0F. DECIDED TO LOWER TEMPS TO 0F AROUND THE TYPICAL COLD SPOT OF CHAMPION. WOULD NOT BE SURPRISED TO SEE THE FAR W (KIWD TOWARD BERGLAND/MARENISCO) DROP JUST AS LOW WITH THE NEW FRESH SNOW COVER. HAVE ONLY GONE 5-10F IN THAT AREA. WILL NEED TO WATCH TRENDS THERE THIS EVENING. A COUPLE OF SHORTWAVES DROPPING SE THRU SCNTRL CANADA AND THE DAKOTAS WILL BRING INCREASING CLOUDS IN WAA/ISENTROPIC ASCENT REGIME. CONDENSATION PRES DEFICITS ARE HIGH...SO IT MAY TAKE A WHILE FOR INCREASING HIGH CLOUDS TO LOWER INTO A MID CLOUD DECK DURING THE DAY. WITH 850MB TEMPS AROUND -12C OVER LAKE SUPERIOR...LES SHOULD CONTINUE ON LAKE SUPERIOR. HOWEVER...WITH SW FLOW...LES WILL BE MOSTLY BE OFFSHORE OF UPPER MI. ONLY EXCEPTION WOULD BE THE TIP OF THE KEWEENAW WHERE THERE MAY BE JUST ENOUGH OF A WRLY COMPONENT -SHSN/FLURRIES TO CLIP THAT AREA. .LONG TERM (00Z SAT ONWARD)... 500 MB TROUGHING CONTINUES TO AFFECT THE AREA FRI NIGHT AND SAT WITH NW FLOW BEFORE ZONAL UPPER LEVEL FLOW MOVES IN TO THE AREA FOR SUN. NAM SHOWING SOME 850-500 MB Q-VECTOR CONVERGENCE MOVING THROUGH FRI NIGHT AND SAT WITH SOME MOISTURE AS WELL. NAM SHOWING SOME ISENTROPIC LIFT AND MOISTURE ON I280K-I285K SURFACES IN THE MID LEVELS OF THE ATMOSPHERE FRI NIGHT. GFS SHOWS THE SAME THING ALONG WITH THE Q-VECTOR CONVERGENCE AND MOISTURE FRI NIGHT AND SAT AS WELL. MOISTURE IS IN THE MID LEVELS HOWEVER...SO WILL GO SLIGHT CHANCE POPS AFTER MIDNIGHT ACROSS THE CWA AS LOW LEVELS WILL TAKE TIME TO SATURATE EXCEPT IN THE KEWEENAW WITH LAKE EFFECT GOING. WHAT THIS WILL DO IS HELP A SOUTHWEST TO WEST ORIENTED LAKE EFFECT SNOW BAND TO GET GOING AND COULD BE ORIENTED ACROSS THE WEST HALF OF THE LAKE ACROSS THE KEWEENAW SOMEWHERE NORTH OF HOUGHTON FRI NIGHT INTO SAT. A SEEDER-FEEDER MECHANISM COULD SET UP WHICH WOULD HELP ACCUMULATIONS OUT. THE PROBLEM IS THE WIND IS WSW TO SW WHICH SHOULD KEEP THE MAJORITY OF THE HEAVY SNOW BAND OFFSHORE OF THE KEWEENAW...BUT WILL HAVE TO WATCH THIS CAREFULLY SINCE IT COULD SNOW PRETTY HEAVILY FRI NIGHT AND SAT WITH THE SEEDER-FEEDER MECHANISM IN PLACE. COULD BE ADVISORY OR CLOSE TO IT...BUT THINK A SMALL ENOUGH AREA IS AFFECTED TO NOT GO WITH ANYTHING RIGHT NOW. THIS WILL HAVE TO BE WATCHED AND IS HIGHLY DEPENDENT ON WIND DIRECTION. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST OTHERWISE. WENT CLOSE TO ADJMVR FOR TEMPERATURES. IN THE EXTENDED...GFS...CANADIAN AND ECMWF SHOW A 500 MB TROUGH ACROSS THE ROCKIES AND SOUTHERN PLAINS 00Z MON WITH ZONAL FLOW ACROSS THE NORTHERN U.S. AT THAT TIME. THE TROUGH MOVES EAST AND AFFECTS THE CWA 00Z TUE. THE TROUGH IS TO THE EAST OF THE CWA 00Z WED WITH RIDGING ACROSS THE NORTHERN PLAINS 00Z WED. RIDGING CONTINUES INTO 00Z THU AND 00Z FRI. TEMPERATURES LOOK TO BE ABOUT NORMAL TO SLIGHTLY BELOW NORMAL. WENT CLOSE TO ADJMXR FOR TEMPERATURES MOSTLY WITH A FEW MINOR TWEAKS HERE AND THERE. ALSO WENT WITH A CHANCE OF SNOW IN EVERY PERIOD BUT SUN NIGHT AND WED WITH RIDGING FOR SUN NIGHT WITH FRONT TO THE NORTH OF THE AREA AND FOR WED WITH A SFC HIGH BUILDING IN AND LIGHT WINDS. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... WINDS SHOULD CONTINUING BACKING TONIGHT...SHUTTING OFF LAKE EFFECT SNOW NEAR KSAW. FLURRIES MAY CONTINUE AT CMX THROUGH THE NIGHT...SO LEFT PRECIP IN THE TAF THROUGH THAT TIME PERIOD. AS WINDS BECOME SW...CHANCE OF LIGHT SNOW COMES BACK INTO CMX. ALTHOUGH CMX MAY FLIRT WITH MVFR CEILINGS EARLY...CONDITIONS AT BOTH LOCATIONS SHOULD REMAIN VFR THROUGH THE PERIOD. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FCST CONCERN IS THE POTENTIAL FOR GALES SAT/SAT EVENING AS A TROF PASSES THE AREA. TIGHTENING PRES GRADIENT WITH AIRMASS STILL UNSTABLE OVER THE LAKE SHOULD SUPPORT LOW END GALES (AT A MINIMUM FREQUENT GALE GUSTS). ANOTHER LOW PRES APPROACHING FROM THE W ON SUN COULD BOOST WINDS BACK TOWARD GALES AGAIN SUN AFTN/EVENING. HAVE ONLY INDICATED WINDS TO 30KT FOR NOW. NO GALES ARE FORESEEN FOR THE REMAINDER OF THIS FCST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...ROLFSON LONG TERM...GJM AVIATION...TAG MARINE..ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 440 PM EST THU NOV 22 2007 .SHORT TERM (TONIGHT AND FRI)... MAIN FCST ISSUES ARE MIN TEMPS TONIGHT AND EVOLUTION OF LES. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF DOMINATING CENTRAL NAMERICA BTWN RIDGES OVER THE W COAST AND JUST OFF THE E COAST. AT THE SFC...A LARGE AREA OF HIGH PRES WAS OVER THE WRN PLAINS WITH A RIDGE EXTENDING NE INTO ONTARIO. AIRMASS FLOWING INTO UPPER MI ON THE NRLY FLOW AHEAD OF THE RIDGE IS VERY DRY. SFC DWPTS UPWIND OF LAKE SUPERIOR ARE AROUND 0F...AND 12Z RAOBS FROM KINL/CWPL SHOWED MEAGER PRECIPITABLE WATER UNDER ONE TENTH OF AN INCH. IN THE CASE OF KINL...THAT IS 25PCT OF NORMAL FOR THIS TIME OF YEAR. THE DRY AIR HAS HAD A SIGNIFICANT NEGATIVE IMPACT ON LES DESPITE 850MB TEMPS AROUND -15C (PER EARLY AFTN TAMDAR SOUNDINGS)...YIELDING A LAKE-850MB DELTA-T AROUND 20C. NOTHING MORE THAN -SHSN/FLURRIES HAVE BEEN NOTED WITH ONE EXCEPTION. LONG FETCH COMBINED WITH PRECONDITIONING FROM LAKE NIPIGON AND LAND BREEZE CONVERGENCE INTO THUNDER BAY N OF ISLE ROYALE HAS LED TO MORE SIGNIFICANT LES STREAMING S AND IMPACTING VERY SMALL AREAS OF FAR WRN GOGEBIC/ONTONAGON COUNTIES. KIWD VCNTY HAS PICKED UP 3-4 INCHES OF SNOW TODAY. WOULDN`T BE SURPRISED IF THERE HAS BEEN LOCALLY MORE. AS THE SFC HIGH PRES RIDGE MOVES ACROSS THE UPPER LAKES REGION TONIGHT...WINDS WILL GRADUALLY BACK TO A SW DIRECTION OVER WRN UPPER MI AND TO A WNW DIRECTION OVER ERN UPPER MI BY SUNRISE. THIS WILL SHIFT LINGERING LES N AND OUT OF GOGEBIC/ONTONAGON COUNTIES. AT THIS POINT...NOT EXPECTING MUCH ACCUMULATION OVER THE WRN FCST AREA TONIGHT DUE TO SHIFTING BANDS AND LOSS OF THE LAKE NIPIGON CONNECTION. FETCH LENGTH WILL IMPROVE INTO THE KEWEENAW LATE TONIGHT WITH THE POSSIBILITY OF LAND BREEZES FOCUSING CONVERGENCE. EVEN SO...UPSTREAM DRY AIRMASS AND LOW INVERSION AROUND 4KFT SHOULD KEEP LES IN CHECK WITH ACCUMULATIONS LESS THAN 1 INCH. TO THE E...THERE SHOULD BE SOME INCREASE IN LIGHT LES AS FETCH LENGTH INCREASES IN NW FLOW. AS FOR TEMPS...THERE WILL BE A GREAT OPPORTUNITY FOR TEMPS TO CRASH TONIGHT OVER THE W AND CNTRL. HIGH PRES RIDGE ARRIVING DURING THE MIDDLE OF THE NIGHT WILL ALLOW WINDS TO GO CALM. THEN ONCE SHARP SFC BASED INVERSION DEVELOPS...RETURN FLOW WILL LIKELY NOT DEVELOP DOWN TO THE SFC UNTIL AFTER SUNRISE. MIN PRECIPITABLE WATER (ONE-TENTH OF AN INCH OR 25-35PCT OF NORMAL) PASSING OVERHEAD AT THE SAME TIME WILL ENHANCE THE COOLING POTENTIAL. LOCATIONS THAT HAVE A LIGHT SNOW COVER SHOULD SEE TEMPS TUMBLE TOWARD 0F. DECIDED TO LOWER TEMPS TO 0F AROUND THE TYPICAL COLD SPOT OF CHAMPION. WOULD NOT BE SURPRISED TO SEE THE FAR W (KIWD TOWARD BERGLAND/MARENISCO) DROP JUST AS LOW WITH THE NEW FRESH SNOW COVER. HAVE ONLY GONE 5-10F IN THAT AREA. WILL NEED TO WATCH TRENDS THERE THIS EVENING. A COUPLE OF SHORTWAVES DROPPING SE THRU SCNTRL CANADA AND THE DAKOTAS WILL BRING INCREASING CLOUDS IN WAA/ISENTROPIC ASCENT REGIME. CONDENSATION PRES DEFICITS ARE HIGH...SO IT MAY TAKE A WHILE FOR INCREASING HIGH CLOUDS TO LOWER INTO A MID CLOUD DECK DURING THE DAY. WITH 850MB TEMPS AROUND -12C OVER LAKE SUPERIOR...LES SHOULD CONTINUE ON LAKE SUPERIOR. HOWEVER...WITH SW FLOW...LES WILL BE MOSTLY BE OFFSHORE OF UPPER MI. ONLY EXCEPTION WOULD BE THE TIP OF THE KEWEENAW WHERE THERE MAY BE JUST ENOUGH OF A WRLY COMPONENT -SHSN/FLURRIES TO CLIP THAT AREA. .LONG TERM (00Z SAT ONWARD)... 500 MB TROUGHING CONTINUES TO AFFECT THE AREA FRI NIGHT AND SAT WITH NW FLOW BEFORE ZONAL UPPER LEVEL FLOW MOVES IN TO THE AREA FOR SUN. NAM SHOWING SOME 850-500 MB Q-VECTOR CONVERGENCE MOVING THROUGH FRI NIGHT AND SAT WITH SOME MOISTURE AS WELL. NAM SHOWING SOME ISENTROPIC LIFT AND MOISTURE ON I280K-I285K SURFACES IN THE MID LEVELS OF THE ATMOSPHERE FRI NIGHT. GFS SHOWS THE SAME THING ALONG WITH THE Q-VECTOR CONVERGENCE AND MOISTURE FRI NIGHT AND SAT AS WELL. MOISTURE IS IN THE MID LEVELS HOWEVER...SO WILL GO SLIGHT CHANCE POPS AFTER MIDNIGHT ACROSS THE CWA AS LOW LEVELS WILL TAKE TIME TO SATURATE EXCEPT IN THE KEWEENAW WITH LAKE EFFECT GOING. WHAT THIS WILL DO IS HELP A SOUTHWEST TO WEST ORIENTED LAKE EFFECT SNOW BAND TO GET GOING AND COULD BE ORIENTED ACROSS THE WEST HALF OF THE LAKE ACROSS THE KEWEENAW SOMEWHERE NORTH OF HOUGHTON FRI NIGHT INTO SAT. A SEEDER-FEEDER MECHANISM COULD SET UP WHICH WOULD HELP ACCUMULATIONS OUT. THE PROBLEM IS THE WIND IS WSW TO SW WHICH SHOULD KEEP THE MAJORITY OF THE HEAVY SNOW BAND OFFSHORE OF THE KEWEENAW...BUT WILL HAVE TO WATCH THIS CAREFULLY SINCE IT COULD SNOW PRETTY HEAVILY FRI NIGHT AND SAT WITH THE SEEDER-FEEDER MECHANISM IN PLACE. COULD BE ADVISORY OR CLOSE TO IT...BUT THINK A SMALL ENOUGH AREA IS AFFECTED TO NOT GO WITH ANYTHING RIGHT NOW. THIS WILL HAVE TO BE WATCHED AND IS HIGHLY DEPENDENT ON WIND DIRECTION. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST OTHERWISE. WENT CLOSE TO ADJMVR FOR TEMPERATURES. IN THE EXTENDED...GFS...CANADIAN AND ECMWF SHOW A 500 MB TROUGH ACROSS THE ROCKIES AND SOUTHERN PLAINS 00Z MON WITH ZONAL FLOW ACROSS THE NORTHERN U.S. AT THAT TIME. THE TROUGH MOVES EAST AND AFFECTS THE CWA 00Z TUE. THE TROUGH IS TO THE EAST OF THE CWA 00Z WED WITH RIDGING ACROSS THE NORTHERN PLAINS 00Z WED. RIDGING CONTINUES INTO 00Z THU AND 00Z FRI. TEMPERATURES LOOK TO BE ABOUT NORMAL TO SLIGHTLY BELOW NORMAL. WENT CLOSE TO ADJMXR FOR TEMPERATURES MOSTLY WITH A FEW MINOR TWEAKS HERE AND THERE. ALSO WENT WITH A CHANCE OF SNOW IN EVERY PERIOD BUT SUN NIGHT AND WED WITH RIDGING FOR SUN NIGHT WITH FRONT TO THE NORTH OF THE AREA AND FOR WED WITH A SFC HIGH BUILDING IN AND LIGHT WINDS. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... SFC HIGH PRES RIDGE FROM THE WRN PLAINS TO ONTARIO WILL MOVE E... CROSSING UPPER MI TONIGHT. AS A RESULT...WINDS WILL GRADUALLY BACK LATE THIS AFTN THRU TONIGHT TO A SW DIRECTION BY DAYBREAK. THIS WILL SHIFT LAKE EFFECT CLOUDS/FLURRIES OVER TIME. WILL CARRY FLURRIES WITH CIGS FLUCTUATING AROUND 3KFT AT KCMX UNTIL AROUND SUNRISE FRI. IT IS AROUND THAT TIME WHEN WINDS WILL FINALLY TAKE ON ENOUGH SW COMPONENT TO SHIFT LAKE EFFECT CLOUDS/FLURRIES N OF THAT AREA. AT KSAW...EXPECT CLOUDS/FLURRIES TO CLEAR OUT EARLY THIS EVENING AS WINDS BECOME NW. BOTH SITES WILL REMAIN UNDER VFR CONDITIONS ONCE THE LAKE EFFECT CLOUDS EXIT. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FCST CONCERN IS THE POTENTIAL FOR GALES SAT/SAT EVENING AS A TROF PASSES THE AREA. TIGHTENING PRES GRADIENT WITH AIRMASS STILL UNSTABLE OVER THE LAKE SHOULD SUPPORT LOW END GALES (AT A MINIMUM FREQUENT GALE GUSTS). ANOTHER LOW PRES APPROACHING FROM THE W ON SUN COULD BOOST WINDS BACK TOWARD GALES AGAIN SUN AFTN/EVENING. HAVE ONLY INDICATED WINDS TO 30KT FOR NOW. NO GALES ARE FORESEEN FOR THE REMAINDER OF THIS FCST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...ROLFSON LONG TERM...GJM AVIATION...ROLFSON MARINE..ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1236 PM EST THU NOV 22 2007 UPDATED FOR 18Z AVIATION DISCUSSION .DISCUSSION (ISSUED AT 400 AM EST)... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEPENING UPR TROF IN CNTRL NAMERICA SANDWICHED BTWN RDG OFF THE W COAST AND OVER THE E. SHRTWVS ROTATING THRU THE BASE OF THE TROF IN THE PLAINS/MS VALLEY ARE CAUSING LO PRES OVER THE OH VALLEY...BUT THIS SYS IS MOVING ENEWD WITH FORCING TO THE S OF THE CWA. FA IS DOMINATED BY COLD NNE FLOW BTWN ARCTIC HI PRES OVER SCNTRL CAN AND THIS LO PRES. ALTHOUGH THE NNE FLOW OVER THE UPR LKS/H85 TEMPS OF -12C/-13C OVER THE LK IS FVRBL FOR LES OVER THE SN BELTS OF THE NCNTRL...THE INFUSION OF VERY DRY AIR OVER ONTARIO (SFC DWPTS BLO 0F) AS SHOWN ON THE 00Z YPL SDNG AND LACK OF CYC FLOW/LLVL CNVGC HAS SGNFTLY LIMITED LES AMTS EVEN OVER THE HIER TERRAIN LOCATIONS. 00Z PWAT BLO 0.10 INCH AT YQD/YPL...SO UPSTREAM AIRMASS UNDER THE ARCTIC HI IS QUITE DRY. MAIN FCST CONCERNS THE NEXT FEW DAYS ARE LES TRENDS/AMTS AND TEMPS. FOR TDAY...SFC HI PRES RDG FM OVER SCNTRL CAN PROGGED TO BLD INTO THE UPR GRT LKS BY 00Z FRI...CAUSING LLVL FLOW TO BACK FM NNE THIS MRNG TO MORE NNW THIS AFTN. ARRIVAL OF EVEN DRIER AIR AS EVIDENCED BY INCRSG H925-85 DWPT DEPRESSION THIS AFTN AS WELL AS MORE ACYC FLOW/FALLING INVRN HGT (FCST TO 2K FT AT IWD BY 00Z) WL PRETTY MUCH END THE LES OVER THE W BY LATE IN THE DAY EVEN THOUGH H85 THERMAL RDG (-13C TO -14C) IS NEARLY OVHD AT 00Z. THE LONGER FETCH/NEARLY UNIDIRECTIONAL FLOW WITHIN THE MIXED LYR OVER ERN LK SUP WL TEND TO MITIGATE THE DRYING A BIT...BUT FCST SDNGS STILL LOOK QUITE DRY EVEN AS LES SHIFTS ITS FOCUS TO AREAS E OF MQT BY 00Z. VARIOUS MOS FCST TEMPS ARE SIMILAR AND SEEM RSNBL FOR HI TEMPS GENERALLY IN THE 20S TO THE LO 30S OVER THE SCNTRL. WHERE THERE ARE DIFFERENCES...WL TEND TOWARD THE LO END OF GUIDANCE PER MIXING TO INVRN BASE ON GFS FCST SDNGS. SHRTWV RDG/SFC HI PRES FCST TO DRIFT INTO THE CWA TNGT. CONSIDERING THE DRYNESS OF THE UPSTREAM AIRMASS AND QUICKLY FALLING TEMPS THERE NOW...ELECTED TO GO BLO MOS GUIDANCE OVER THE INTERIOR W HALF AS THIS AREA WL HAVE THE BEST CHC FOR REALLY LGT WINDS CLOSER TO THE HI CENTER FCST TO BLD INTO MO BY 12Z FRI. SOME LGT LES/MORE SC WL PERSIST E OF MQT WITH LLVL FLOW SLOWLY BACKING FM NNW TO WNW DURING THE NGT. INFLUX OF DRY AIR/LO INVRN HGT IN THE 3-5K FT RANGE/ SHIFTING WINDS WL SGNFTLY LIMIT ANY ACCUM. MAINTAINED 30 POP OVER THE KEWEENAW AFT MIDNGT TO ACCOUNT FOR INCRSG MSTR/FVRBL CNVGC IN THE WLY FLOW OVER WRN LK SUP. BUT DRY AIRMASS WL NEGATIVELY IMPACT THIS BAND AS WELL. ON FRI...NRN BRANCH SHRTWV/LO PRES TROF DROPPING THRU SCNTRL CAN WL REACH NW ONTARIO/MN BY 00Z SAT. AIRMASS IN ADVANCE OF THIS SHRTWV IS TOO DRY FOR ANY LARGER SCALE PCPN...BUT APRCH OF SYS/DPVA/H85-5 QVECTOR CNVGC LATER IN THE AFTN MAY LIFT INVRN BASE OVER LES BAND OVER WRN LK SUP. BUT LLVL FLOW MAY ALSO BACK ENUF FOR BAND TO DRIFT AWAY FM ALL BUT THE NW CORNER OF THE KEWEENAW. ANY LINGERING LES OVER THE E WL END EARLY WITH BACKING LLVL FLOW. OTRW...THERE WL BE AN INCRS IN HI/MID CLD ESPECIALLY OVER THE NW IN THE AFTN. FCST SDNGS SUG MAX TEMPS WL REMAIN BLO FRZG AT MOST INTERIOR SPOTS EXCEPT OVER THE SCNTRL AND E WITH SW FLOW ENDING LK SUP MODERATION. SHRTWV/SFC LO PRES TROF FCST TO SWING INTO THE UPR LKS FRI NGT... WITH VEERING LLVL FLOW SHOWN AFT MIDNGT. SO EXPECT LES BAND OVER MAINLY THE OPEN WATERS OF WRN LK SUP FRI AFTN/EVNG TO DRIFT ONSHORE DURING THE NGT...IMPACTING MAINLY AREAS N OF CMX WITH MORE 250-260 FLOW. OTRW...ADDED 20 POPS TO THE REST OF THE FA AFT MIDNGT WITH GFS FCST SDNGS SHOWING SGNFT MOISTENING/UPR DVGC DESPITE LACK OF ISENTROPIC LIFT IN DRY AIRMASS IN AN ABSOLUTE SENSE (FCST PWAT ONLY ARND 0.33 INCH). SOME CONCERN FLOW MIGHT BACK ENUF TO ALLOW SOME MOISTENING OFF LK MI INTO THE ERN ZNS...BUT H925 FLOW PROGGED TO BACK NO MORE THAN 240 OR SO AHEAD OF THE SHRTWV...NOT ENUF TO WARRANT MENTION OF LES OFF LK MI. RISING HGTS/DVLPMNT OF MORE ACYC FLOW IN WAKE OF SHRTWV ON SAT WL ALLOW FOR DCRSG CLDS IN MOST PLACES W-E AFT LINGERING MRNG 20-30 POPS. BUT SOME LES WL PERSIST ALL DAY OVER THE KEWEENAW IN EXPECTED WLY FLOW. NOT OUT OF QUESTION AN LES ADVY MAY BE REQUIRED FOR AT LEAST KEWEENAW COUNTY FOR FRI NGT THRU AT LEAST SAT MRNG BEFORE ARRIVAL OF NEGATIVE DYNAMICS/SINKING INVRN BASE/MID LVL DRYING NEGATIVELY IMPACT LES THERE. THESE SHSN WL GRDLY END SAT NGT AS COLD AIR RETREATS INTO ONTARIO AND LK INSTABILITY WANES IN WAD REGIME. COORDINATED WITH GRB. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... SFC HIGH PRES RIDGE FROM THE WRN PLAINS TO ONTARIO WILL MOVE E... CROSSING UPPER MI TONIGHT. AS A RESULT...WINDS WILL GRADUALLY BACK LATE THIS AFTN THRU TONIGHT TO A SW DIRECTION BY DAYBREAK. THIS WILL SHIFT LAKE EFFECT CLOUDS/FLURRIES OVER TIME. WILL CARRY FLURRIES WITH CIGS FLUCTUATING AROUND 3KFT AT KCMX UNTIL AROUND SUNRISE FRI. IT IS AROUND THAT TIME WHEN WINDS WILL FINALLY TAKE ON ENOUGH SW COMPONENT TO SHIFT LAKE EFFECT CLOUDS/FLURRIES N OF THAT AREA. AT KSAW...EXPECT CLOUDS/FLURRIES TO CLEAR OUT EARLY THIS EVENING AS WINDS BECOME NW. BOTH SITES WILL REMAIN UNDER VFR CONDITIONS ONCE THE LAKE EFFECT CLOUDS EXIT. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NO GALES FORESEEN AS HIGH PRESSURE MOVES IN AND REMAINS IN CONTROL THROUGH FRIDAY. A TROUGH MOVES THROUGH ON SATURDAY AND AGAIN ON MONDAY. STILL...WINDS TO ABOUT 30 KNOTS WILL STILL BE POSSIBLE SATURDAY INTO EARLY SUNDAY...ASSOCIATED WITH THAT NEXT TROUGH. FOR THIS ISSUANCE THE MAIN CHANGE INCLUDED INCREASING AND TURNING THE WINDS MORE WESTERLY FOR SATURDAY EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...ROLFSON MARINE...KF mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 608 AM EST THU NOV 22 2007 ...UPDATED FOR 12Z AVIATION DISCUSSSION... .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEPENING UPR TROF IN CNTRL NAMERICA SANDWICHED BTWN RDG OFF THE W COAST AND OVER THE E. SHRTWVS ROTATING THRU THE BASE OF THE TROF IN THE PLAINS/MS VALLEY ARE CAUSING LO PRES OVER THE OH VALLEY...BUT THIS SYS IS MOVING ENEWD WITH FORCING TO THE S OF THE CWA. FA IS DOMINATED BY COLD NNE FLOW BTWN ARCTIC HI PRES OVER SCNTRL CAN AND THIS LO PRES. ALTHOUGH THE NNE FLOW OVER THE UPR LKS/H85 TEMPS OF -12C/-13C OVER THE LK IS FVRBL FOR LES OVER THE SN BELTS OF THE NCNTRL...THE INFUSION OF VERY DRY AIR OVER ONTARIO (SFC DWPTS BLO 0F) AS SHOWN ON THE 00Z YPL SDNG AND LACK OF CYC FLOW/LLVL CNVGC HAS SGNFTLY LIMITED LES AMTS EVEN OVER THE HIER TERRAIN LOCATIONS. 00Z PWAT BLO 0.10 INCH AT YQD/YPL...SO UPSTREAM AIRMASS UNDER THE ARCTIC HI IS QUITE DRY. MAIN FCST CONCERNS THE NEXT FEW DAYS ARE LES TRENDS/AMTS AND TEMPS. FOR TDAY...SFC HI PRES RDG FM OVER SCNTRL CAN PROGGED TO BLD INTO THE UPR GRT LKS BY 00Z FRI...CAUSING LLVL FLOW TO BACK FM NNE THIS MRNG TO MORE NNW THIS AFTN. ARRIVAL OF EVEN DRIER AIR AS EVIDENCED BY INCRSG H925-85 DWPT DEPRESSION THIS AFTN AS WELL AS MORE ACYC FLOW/FALLING INVRN HGT (FCST TO 2K FT AT IWD BY 00Z) WL PRETTY MUCH END THE LES OVER THE W BY LATE IN THE DAY EVEN THOUGH H85 THERMAL RDG (-13C TO -14C) IS NEARLY OVHD AT 00Z. THE LONGER FETCH/NEARLY UNIDIRECTIONAL FLOW WITHIN THE MIXED LYR OVER ERN LK SUP WL TEND TO MITIGATE THE DRYING A BIT...BUT FCST SDNGS STILL LOOK QUITE DRY EVEN AS LES SHIFTS ITS FOCUS TO AREAS E OF MQT BY 00Z. VARIOUS MOS FCST TEMPS ARE SIMILAR AND SEEM RSNBL FOR HI TEMPS GENERALLY IN THE 20S TO THE LO 30S OVER THE SCNTRL. WHERE THERE ARE DIFFERENCES...WL TEND TOWARD THE LO END OF GUIDANCE PER MIXING TO INVRN BASE ON GFS FCST SDNGS. SHRTWV RDG/SFC HI PRES FCST TO DRIFT INTO THE CWA TNGT. CONSIDERING THE DRYNESS OF THE UPSTREAM AIRMASS AND QUICKLY FALLING TEMPS THERE NOW...ELECTED TO GO BLO MOS GUIDANCE OVER THE INTERIOR W HALF AS THIS AREA WL HAVE THE BEST CHC FOR REALLY LGT WINDS CLOSER TO THE HI CENTER FCST TO BLD INTO MO BY 12Z FRI. SOME LGT LES/MORE SC WL PERSIST E OF MQT WITH LLVL FLOW SLOWLY BACKING FM NNW TO WNW DURING THE NGT. INFLUX OF DRY AIR/LO INVRN HGT IN THE 3-5K FT RANGE/ SHIFTING WINDS WL SGNFTLY LIMIT ANY ACCUM. MAINTAINED 30 POP OVER THE KEWEENAW AFT MIDNGT TO ACCOUNT FOR INCRSG MSTR/FVRBL CNVGC IN THE WLY FLOW OVER WRN LK SUP. BUT DRY AIRMASS WL NEGATIVELY IMPACT THIS BAND AS WELL. ON FRI...NRN BRANCH SHRTWV/LO PRES TROF DROPPING THRU SCNTRL CAN WL REACH NW ONTARIO/MN BY 00Z SAT. AIRMASS IN ADVANCE OF THIS SHRTWV IS TOO DRY FOR ANY LARGER SCALE PCPN...BUT APRCH OF SYS/DPVA/H85-5 QVECTOR CNVGC LATER IN THE AFTN MAY LIFT INVRN BASE OVER LES BAND OVER WRN LK SUP. BUT LLVL FLOW MAY ALSO BACK ENUF FOR BAND TO DRIFT AWAY FM ALL BUT THE NW CORNER OF THE KEWEENAW. ANY LINGERING LES OVER THE E WL END EARLY WITH BACKING LLVL FLOW. OTRW...THERE WL BE AN INCRS IN HI/MID CLD ESPECIALLY OVER THE NW IN THE AFTN. FCST SDNGS SUG MAX TEMPS WL REMAIN BLO FRZG AT MOST INTERIOR SPOTS EXCEPT OVER THE SCNTRL AND E WITH SW FLOW ENDING LK SUP MODERATION. SHRTWV/SFC LO PRES TROF FCST TO SWING INTO THE UPR LKS FRI NGT... WITH VEERING LLVL FLOW SHOWN AFT MIDNGT. SO EXPECT LES BAND OVER MAINLY THE OPEN WATERS OF WRN LK SUP FRI AFTN/EVNG TO DRIFT ONSHORE DURING THE NGT...IMPACTING MAINLY AREAS N OF CMX WITH MORE 250-260 FLOW. OTRW...ADDED 20 POPS TO THE REST OF THE FA AFT MIDNGT WITH GFS FCST SDNGS SHOWING SGNFT MOISTENING/UPR DVGC DESPITE LACK OF ISENTROPIC LIFT IN DRY AIRMASS IN AN ABSOLUTE SENSE (FCST PWAT ONLY ARND 0.33 INCH). SOME CONCERN FLOW MIGHT BACK ENUF TO ALLOW SOME MOISTENING OFF LK MI INTO THE ERN ZNS...BUT H925 FLOW PROGGED TO BACK NO MORE THAN 240 OR SO AHEAD OF THE SHRTWV...NOT ENUF TO WARRANT MENTION OF LES OFF LK MI. RISING HGTS/DVLPMNT OF MORE ACYC FLOW IN WAKE OF SHRTWV ON SAT WL ALLOW FOR DCRSG CLDS IN MOST PLACES W-E AFT LINGERING MRNG 20-30 POPS. BUT SOME LES WL PERSIST ALL DAY OVER THE KEWEENAW IN EXPECTED WLY FLOW. NOT OUT OF QUESTION AN LES ADVY MAY BE REQUIRED FOR AT LEAST KEWEENAW COUNTY FOR FRI NGT THRU AT LEAST SAT MRNG BEFORE ARRIVAL OF NEGATIVE DYNAMICS/SINKING INVRN BASE/MID LVL DRYING NEGATIVELY IMPACT LES THERE. THESE SHSN WL GRDLY END SAT NGT AS COLD AIR RETREATS INTO ONTARIO AND LK INSTABILITY WANES IN WAD REGIME. COORDINATED WITH GRB. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... 500MB TROUGH WILL BE TEMPORARILY REPLACED WITH SOME RIDGING TOWARDS THE END OF THE PERIOD OVERNIGHT. DRY AIR WILL CONTINUE TO SLOWLY WORK INTO BOTH CMX AND SAW...WITH CONDITIONS EXPECTED TO IMPROVE FROM TEMPORARY HIGH MVFR TO VFR. STILL FIGURE DAYTIME HEATING TO COMBINE WITH THE DRY AIR TO HELP SCATTER OUT THE CLOUDS AT CMX AROUND 21Z. SAW SHOULD SEE CLEARING TOO...MORE LIKELY AFTER THE WINDS TURN NW WHICH LOOK TO OCCUR AROUND 01Z. MODEL WISE...BOTH THE NAM AND GFS SEEMS RELATIVELY CONSISTENT SCOURING OUT THE LOWER LEVEL CLOUDS. HOWEVER THE MID DECK IS A LITTLE DIFFERENT...WITH THE GFS CONTAINING MUCH MORE MOISTURE BETWEEN 300 AND 500MB. LOOKING UPSTREAM IT SEEMS THAT THE GFS IS A LITTLE OVERDONE GIVEN THE LATEST SOUNDINGS FROM UPSTREAM...SO HAVE SIDED CLOSER TO THE DRIER NAM SOLUTION. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NO GALES FORESEEN AS HIGH PRESSURE MOVES IN AND REMAINS IN CONTROL THROUGH FRIDAY. A TROUGH MOVES THROUGH ON SATURDAY AND AGAIN ON MONDAY. STILL...WINDS TO ABOUT 30 KNOTS WILL STILL BE POSSIBLE SATURDAY INTO EARLY SUNDAY...ASSOCIATED WITH THAT NEXT TROUGH. FOR THIS ISSUANCE THE MAIN CHANGE INCLUDED INCREASING AND TURNING THE WINDS MORE WESTERLY FOR SATURDAY EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...KF MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 AM EST THU NOV 22 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEPENING UPR TROF IN CNTRL NAMERICA SANDWICHED BTWN RDG OFF THE W COAST AND OVER THE E. SHRTWVS ROTATING THRU THE BASE OF THE TROF IN THE PLAINS/MS VALLEY ARE CAUSING LO PRES OVER THE OH VALLEY...BUT THIS SYS IS MOVING ENEWD WITH FORCING TO THE S OF THE CWA. FA IS DOMINATED BY COLD NNE FLOW BTWN ARCTIC HI PRES OVER SCNTRL CAN AND THIS LO PRES. ALTHOUGH THE NNE FLOW OVER THE UPR LKS/H85 TEMPS OF -12C/-13C OVER THE LK IS FVRBL FOR LES OVER THE SN BELTS OF THE NCNTRL...THE INFUSION OF VERY DRY AIR OVER ONTARIO (SFC DWPTS BLO 0F) AS SHOWN ON THE 00Z YPL SDNG AND LACK OF CYC FLOW/LLVL CNVGC HAS SGNFTLY LIMITED LES AMTS EVEN OVER THE HIER TERRAIN LOCATIONS. 00Z PWAT BLO 0.10 INCH AT YQD/YPL...SO UPSTREAM AIRMASS UNDER THE ARCTIC HI IS QUITE DRY. MAIN FCST CONCERNS THE NEXT FEW DAYS ARE LES TRENDS/AMTS AND TEMPS. FOR TDAY...SFC HI PRES RDG FM OVER SCNTRL CAN PROGGED TO BLD INTO THE UPR GRT LKS BY 00Z FRI...CAUSING LLVL FLOW TO BACK FM NNE THIS MRNG TO MORE NNW THIS AFTN. ARRIVAL OF EVEN DRIER AIR AS EVIDENCED BY INCRSG H925-85 DWPT DEPRESSION THIS AFTN AS WELL AS MORE ACYC FLOW/FALLING INVRN HGT (FCST TO 2K FT AT IWD BY 00Z) WL PRETTY MUCH END THE LES OVER THE W BY LATE IN THE DAY EVEN THOUGH H85 THERMAL RDG (-13C TO -14C) IS NEARLY OVHD AT 00Z. THE LONGER FETCH/NEARLY UNIDIRECTIONAL FLOW WITHIN THE MIXED LYR OVER ERN LK SUP WL TEND TO MITIGATE THE DRYING A BIT...BUT FCST SDNGS STILL LOOK QUITE DRY EVEN AS LES SHIFTS ITS FOCUS TO AREAS E OF MQT BY 00Z. VARIOUS MOS FCST TEMPS ARE SIMILAR AND SEEM RSNBL FOR HI TEMPS GENERALLY IN THE 20S TO THE LO 30S OVER THE SCNTRL. WHERE THERE ARE DIFFERENCES...WL TEND TOWARD THE LO END OF GUIDANCE PER MIXING TO INVRN BASE ON GFS FCST SDNGS. SHRTWV RDG/SFC HI PRES FCST TO DRIFT INTO THE CWA TNGT. CONSIDERING THE DRYNESS OF THE UPSTREAM AIRMASS AND QUICKLY FALLING TEMPS THERE NOW...ELECTED TO GO BLO MOS GUIDANCE OVER THE INTERIOR W HALF AS THIS AREA WL HAVE THE BEST CHC FOR REALLY LGT WINDS CLOSER TO THE HI CENTER FCST TO BLD INTO MO BY 12Z FRI. SOME LGT LES/MORE SC WL PERSIST E OF MQT WITH LLVL FLOW SLOWLY BACKING FM NNW TO WNW DURING THE NGT. INFLUX OF DRY AIR/LO INVRN HGT IN THE 3-5K FT RANGE/ SHIFTING WINDS WL SGNFTLY LIMIT ANY ACCUM. MAINTAINED 30 POP OVER THE KEWEENAW AFT MIDNGT TO ACCOUNT FOR INCRSG MSTR/FVRBL CNVGC IN THE WLY FLOW OVER WRN LK SUP. BUT DRY AIRMASS WL NEGATIVELY IMPACT THIS BAND AS WELL. ON FRI...NRN BRANCH SHRTWV/LO PRES TROF DROPPING THRU SCNTRL CAN WL REACH NW ONTARIO/MN BY 00Z SAT. AIRMASS IN ADVANCE OF THIS SHRTWV IS TOO DRY FOR ANY LARGER SCALE PCPN...BUT APRCH OF SYS/DPVA/H85-5 QVECTOR CNVGC LATER IN THE AFTN MAY LIFT INVRN BASE OVER LES BAND OVER WRN LK SUP. BUT LLVL FLOW MAY ALSO BACK ENUF FOR BAND TO DRIFT AWAY FM ALL BUT THE NW CORNER OF THE KEWEENAW. ANY LINGERING LES OVER THE E WL END EARLY WITH BACKING LLVL FLOW. OTRW...THERE WL BE AN INCRS IN HI/MID CLD ESPECIALLY OVER THE NW IN THE AFTN. FCST SDNGS SUG MAX TEMPS WL REMAIN BLO FRZG AT MOST INTERIOR SPOTS EXCEPT OVER THE SCNTRL AND E WITH SW FLOW ENDING LK SUP MODERATION. SHRTWV/SFC LO PRES TROF FCST TO SWING INTO THE UPR LKS FRI NGT... WITH VEERING LLVL FLOW SHOWN AFT MIDNGT. SO EXPECT LES BAND OVER MAINLY THE OPEN WATERS OF WRN LK SUP FRI AFTN/EVNG TO DRIFT ONSHORE DURING THE NGT...IMPACTING MAINLY AREAS N OF CMX WITH MORE 250-260 FLOW. OTRW...ADDED 20 POPS TO THE REST OF THE FA AFT MIDNGT WITH GFS FCST SDNGS SHOWING SGNFT MOISTENING/UPR DVGC DESPITE LACK OF ISENTROPIC LIFT IN DRY AIRMASS IN AN ABSOLUTE SENSE (FCST PWAT ONLY ARND 0.33 INCH). SOME CONCERN FLOW MIGHT BACK ENUF TO ALLOW SOME MOISTENING OFF LK MI INTO THE ERN ZNS...BUT H925 FLOW PROGGED TO BACK NO MORE THAN 240 OR SO AHEAD OF THE SHRTWV...NOT ENUF TO WARRANT MENTION OF LES OFF LK MI. RISING HGTS/DVLPMNT OF MORE ACYC FLOW IN WAKE OF SHRTWV ON SAT WL ALLOW FOR DCRSG CLDS IN MOST PLACES W-E AFT LINGERING MRNG 20-30 POPS. BUT SOME LES WL PERSIST ALL DAY OVER THE KEWEENAW IN EXPECTED WLY FLOW. NOT OUT OF QUESTION AN LES ADVY MAY BE REQUIRED FOR AT LEAST KEWEENAW COUNTY FOR FRI NGT THRU AT LEAST SAT MRNG BEFORE ARRIVAL OF NEGATIVE DYNAMICS/SINKING INVRN BASE/MID LVL DRYING NEGATIVELY IMPACT LES THERE. THESE SHSN WL GRDLY END SAT NGT AS COLD AIR RETREATS INTO ONTARIO AND LK INSTABILITY WANES IN WAD REGIME. COORDINATED WITH GRB. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... NORTHERLY FLOW AROUND HIGH PRESSURE OVER MANITOBA CONTINUES TO DRIVE DRY AIR SOUTHWARD FROM ONTARIO ACROSS LAKE SUPERIOR. THIS DRY AIR HAS HELPED KEPT VISIBILITIES VFR AND CEILINGS HIGH MVFR TO VFR FROM THE LAKE EFFECT SNOW. AS MORE DRY AIR IS PULLED SOUTH ACROSS LAKE SUPERIOR...THE LAKE EFFECT SNOW SHOULD CONTINUE TO DIMINISH. IN FACT...DAYTIME HEATING SHOULD COMBINE WITH THE DRY AIR TO HELP SCATTER OUT THE CLOUDS AT CMX AROUND 21Z. SAW SHOULD SEE CLEARING TOO...MORE LIKELY AFTER THE WINDS TURN NW WHICH LOOK TO OCCUR AROUND 01Z. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NO GALES FORESEEN AS HIGH PRESSURE MOVES IN AND REMAINS IN CONTROL THROUGH FRIDAY. A TROUGH MOVES THROUGH ON SATURDAY AND AGAIN ON MONDAY. STILL...WINDS TO ABOUT 30 KNOTS WILL STILL BE POSSIBLE SATURDAY INTO EARLY SUNDAY...ASSOCIATED WITH THAT NEXT TROUGH. FOR THIS ISSUANCE THE MAIN CHANGE INCLUDED INCREASING AND TURNING THE WINDS MORE WESTERLY FOR SATURDAY EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...AJ MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 551 PM CST FRI NOV 23 2007 .DISCUSSION... TROUGH AXIS NOW MOVING ACROSS CNTRL ND. PLENTY OF RADAR ECHOES IN THE WARM ADVECTION PATTERN...BUT THEY ARE MOSTLY ALOFT UNTIL ONE GETS FAR ENOUGH NORTH WHERE LOW SATURATION IS BETTER. STILL...A FEW FLURRIES FARTHER SOUTH EMANATING FROM THE MID LEVEL CLOUDS. AS THE TROUGH MOVES SE...LATEST RUC BRINGS SIGNIFICANT LOW LEVEL SATURATION TO AN RNH-RWF LINE BY 06Z...AND NAM BRINGS IT ACROSS ALL BUT SC MN BY 12Z. SIMILAR CONSIDERATIONS AS IN PREVIOUS DISCUSSION SUGGEST KEEPING SNOW SHOWERS OVERNIGHT AS WELL A COATING OF SNOW... MAINLY FROM WC MN ACROSS TO WC WISC. ONCE TROUGH GOES BY...MODELS ARE IN PRETTY GOOD AGREEMENT FOR ABOUT THREE MORE DAYS. WITH BROAD WESTERLY UPPER FLOW AXIS TO OUR NORTH... AND ANOTHER UPPER LOW TO THE SOUTHWEST... MN AND WI WILL BE IN A PACIFIC FLOW PATTERN INTO TUESDAY. SFC TROUGH IS PROGGED TO MOVE ACROSS SUNDAY AFTERNOON/EVENING. RELATIVELY DRY AIR AND WESTERLY TRAJECTORIES SUGGEST SUNDAY WILL BE A RATHER MILD DAY. WOULD NOT BE SURPRISED TO SEE A FEW SPOTS IN WC/SW MN REACHING 50 DEGREES. REST OF AREA WILL BE INTO THE MID/UPPER 40S. THE MAIN QUESTION IS EXTENT OF HIGH LEVEL CLOUDINESS. NEXT SYSTEM OF SIGNIFICANCE WILL BE WEDNESDAY. BOTH ECMWF AND GFS DEPICT LARGE TROUGH MOVING ACROSS THE SOUTHWEST STATES INTO THE SOUTH CENTRAL PART OF THE COUNTRY...AT THE SAME TIME AS CANADIAN LOW SWINGS A TROUGH ACROSS SOUTH CENTRAL CANADA. 12Z ECMWF IS A LITTLE STRONGER THAN THE 00Z VERSION WAS...AND THE 12Z RUN ALSO SHOWS A HINT OF POSSIBLE PHASING. ECMWF 850 MB LOW IS STRONGER AND A BIT FARTHER NORTH THAN THE OPERATIONAL GFS. INTERESTINGLY... THE 12Z GFS ENSEMBLE MEAN SHOWS THE 850 LOW FARTHER NORTH THAN THE OPERATIONAL GFS DOES. HAVE CONTINUED POPS FOR MIDWEEK. SPAGHETTI CHARTS SOME SOME DISTRIBUTION IN THEIR SOLUTIONS BUT NOT AS MUCH AS ONE MIGHT EXPECT. && .AVIATION.../00Z TAF ISSUANCE/ DETERIORATING CONDITIONS EXPECTED THROUGH THE EVENING AS AN UPPER LEVEL TROUGH SWINGS ACROSS MINNESOTA. AT THE SURFACE...SOUTH TO SOUTHWEST WINDS CONTINUE WITH A MIX OF MID AND HIGH CLOUDS ACROSS JUST ABOUT THE ENTIRE AREA. OBS AND SATELLITE IMAGERY SHOWS MVFR CLOUD DECK...WITH LOWER END VFR CLOUDS ON ITS LEADING EDGE... MAKING PROGRESS SOUTHEAST OUT OF THE DAKOTAS AND NORTHWEST MINNESOTA. SNOW SHOWERS ARE ALSO BEING OBSERVED JUST TO THE NORTHWEST OF KAXN AND KSTC WITH LOWEST VISBYS DOWN BETWEEN 1 AND 3 MILES AND LOWEST CIGS TO BETWEEN 1 AND 2 KFT. EXPECT THESE TRENDS TO TRANSLATE SOUTHEAST THROUGH THE EARLY EVENING AND AFFECT MINNESOTA SITES AND KRNH THROUGH THE COURSE OF THE NIGHT. CIGS WILL BE THE MAIN CHALLENGE. THE LOWEST CIGS WILL PROBABLY ARRIVE LATER IN THE EVENING AS COLDER AIR FILTERS IN BUT PERIODIC REDUCTION IN SNOW SHOWERS...ESPECIALLY ACROSS CENTRAL MINNESOTA WILL BE POSSIBLE. MVFR CLOUDS MAY NOT MAKE IT AS FAR AS KEAU. SOME LIGHT SNOW ACCUMULATION WILL BE POSSIBLE UNDER THE HEAVIER SHOWERS BUT SHOULD NOT AMOUNT TO MORE THAN A DUSTING OR A TENTH OR 2. MVFR CLOUDS ARE EXPECTED TO HANG AROUND THROUGH DAYBREAK BEFORE DECREASING ALLOWING VFR CONDITIONS TO RETURN. SOUTHWEST WINDS WILL INCREASE DURING THE LATE MORNING HOURS WITH SOME GUSTS TO AROUND 25 KTS POSSIBLE FOR A SHORT TIME IN THE AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ TDK/MDB mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 548 AM CST THU NOV 22 2007 .UPDATE...FOR 12Z AVIATION DISCUSSION BELOW && .DISCUSSION.../ISSUED 325 AM CST THU NOV 22 2007/ FORECAST CONCERN NEAR TERM...IS THE LINGERING SNOW FLURRIES AND PERSISTENT CLOUD COVER. THE LATEST SATELLITE AND SFC OBSERVATIONS SHOWED CLOUDS HAD CLEARED OVER THE NORTHERN ONE THIRD OF THE STATE. 850 MB TEMPS OF -15 DEG CELSIUS...LAKE EFFECT SNOW SHOWERS CONTINUE TO DEVELOP OVER THE WARM WATERS AND LARGE AREA LAKES OVER EASTERN HALF OF MN AND WEST CENTRAL WISCONSIN. THIS TREND SHOULD CONTINUE THROUGHOUT MUCH OF THE DAY. THUS KEPT THE MENTION OF SNOW FLURRIES OVER SOUTHEAST HALF OF CWA INTO LATE AFTERNOON. IN THE MEDIUM RANGE...MODELS ARE IN GENERAL AGREEMENT OUT THROUGH 120 HOURS. THE UPPER AIRFLOW WILL REMAIN NORTHWEST THRU SUNDAY MRNG...THEN TURN MORE ZONAL AFTERWARDS. TEMPERATURES SLOWLY MODERATING INTO THE MIDDLE 30S TO AROUND 40 DEGREES BY SUNDAY AFTERNOON. BOTH THE LATEST ECMWF AND GFS MODELS KEEPS MUCH OF THE UPPER MIDWEST DRY THROUGH THE BALANCE OF THE FORECAST. NOT MUCH CHANGE TO THE OVERALL FORECAST. && .AVIATION.../12Z TAF ISSUANCE/ THE MORNING LOW CLOUD SCENARIO IS CAPTURE WELL BY THE 06Z NAM AND 03Z RUC 900MB RH PROGS...WHICH REMAIN SATURATED THROUGH 18Z. THEREFORE EXPECT MVFR TO LOW-END VFR CIGS TO PERSIST ACROSS TAF SITES INTO THE AFTERNOON. SCATTERED FLURRIES WILL ALSO LINGER THIS MORNING...ALTHOUGH NO REDUCTION IN VISIBILITIES IS EXPECTED. NORTHERLY MORNING WINDS WILL BACK TO WEST/NORTHWESTERLY THIS AFTERNOON...AND THEN BECOME SOUTHWESTERLY THIS EVENING. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 505 AM CST FRI NOV 23 2007 .DISCUSSION...SHORT TERM(TODAY THROUGH SATURDAY NIGHT) LATEST SURFACE ANALYSIS SHOWING THE STRONG COLD FRONT NOW ACROSS THE CENTRAL GULF OF MEXICO STILL MOVING STEADILY SEWD WHILE A 1035MB HIGH CENTER IN SERN KS MOVING EASTWARD ACROSS THE OZARKS. CURRENT RADAR/SATELLITE IMAGERY HAS A NARROW BAND OF LIGHT RAIN/SHRA ALONG THE I-20 CORRIDOR RACING EAST AT 45 MPH AS A MID LEVEL SHORTWAVE CROSSES THE LOWER MS VALLEY THIS MORNING. WE HAVE RECEIVED A COUPLE OF REPORTS OF BRIEF WET SLEET MELTING ON CONTACT. WILL KEEP MENTION OF SPRINKLES ACROSS SRN MS THROUGH MID MORNING AS RUC/WRF SHOW THE PRECIP QUICKLY DRYING UP. EVEN SO...CLOUD COVER WILL PREVAIL THROUGH MIDDAY BEFORE GRADUALLY DRYING UP FROM N TO S THIS AFTERNOON. SURFACE TEMPS FALLING THROUGH THE U30S TO L40S WITH WETBULBS HOLDING ABOVE FREEZING AS CAA SLOWED A LITTLE BY THE EXTRA PRECIPITATION. BY THIS AFTERNOON...BETTER DOWNGLIDE PREVAILS ALLOWING CLOUDS TO BREAK UP AS THE SURFACE HIGH(1034MB) BUILDS INTO SERN MO TOWARD THE OH VALLEY. SOME ADDITIONAL CIRRUS SHOULD STREAK TOWARD THE LOWER MS VALLEY UNDER A W TO E 120-130KT 200MB JET AXIS SET UP ACROSS THE GULF STATES BY TONIGHT. THE HIGH SHIFTS EWD THROUGH THE OH VALLEY WITH ISENTROPIC UPGLIDE BEGINNING IN THE 300-315K LAYERS MAINLY AFTER MIDNIGHT. ECMWF REMAINS THE MOST AGGRESSIVE WITH LIGHT RAINS BREAKING OUT FROM SW CWFA TOWARD THE NE EARLY SATURDAY MORNING. TIMING AND THICKNESS OF THESE CLOUDS WILL ULTIMATELY DETERMINE HOW COLD WE COULD GET SO WILL NOT DEVIATE MUCH FROM MAV MOS AS YET. ON SATURDAY...UPGLIDE INCREASES WITH WIDESPREAD CONDENSATION PRESSURE DEFICITS OF LESS THAN 2MB IN THE 305-315K LAYERS ACROSS THE ENTIRE CWFA. EXPECT STEADY RAINS OVER AT LEAST THE SW HALF OF THE CWFA BY EARLY AFTERNOON. HAVE BOOSTED POPS FOR MUCH OF THE AREA FROM SATURDAY AFTERNOON THROUGH SATURDAY NIGHT WITH AT LEAST A COUPLE OF SHORTWAVES PROVIDING PERIODIC ENHANCEMENT OF UVV. WE COULD SEE NEAR 1 INCH QPF AMOUNTS BY MIDNIGHT SATURDAY NIGHT AT MANY LOCATIONS WITH MORE TO FOLLOW. /40/ SIGNIFICANT SEVERE WEATHER AND HEAVY RAIN EVENT STILL ON TAP FOR SUNDAY AND SUNDAY NIGHT... IT CONTINUES TO LOOK MORE LIKELY THAT SEVERE WEATHER AND HEAVY RAINFALL WILL DEVELOP OVER THE FORECAST AREA SUNDAY AND PERSIST THROUGH SUNDAY NIGHT. THE POTENTIAL FOR HEAVY RAINFALL EXISTS OVER THE ENTIRE AREA...WHILE THE GREATEST POTENTIAL FOR SEVERE THUNDERSTORMS IS ALONG AND SOUTHEAST OF THE NATCHEZ TRACE PARKWAY. WE ARE MORE CONFIDENT NOW WITH THESE AREAL DESIGNATIONS...BUT SEVERE WEATHER STILL CANNOT BE RULED OUT OVER THE ENTIRE AREA. THE 00Z OPERATIONAL GFS/ECMWF/GFS ENSEMBLE AND 06Z GFS ARE IN GOOD AGREEMENT ON THE TIMING AND PLACEMENT OF THE SURFACE LOW CIRCULATION...TRACKING IT NEWD ALONG THE NATCHEZ TRACE SUNDAY NIGHT. THIS IS IN AGREEMENT WITH PREVIOUS FORECAST THINKING AND SEE NO REASON TO DEVIATE FROM IT AT THIS POINT. AS THE PRIMARY SHORTWAVE TROUGH APPROACHES SUNDAY...SOUTHERLY LOW-LEVEL FLOW AND MOISTURE TRANSPORT WILL INCREASE DRAMATICALLY (850MB FROM 20KT TO 50KT AND 850MB THETAE FROM ~320 TO 330+ DEG K) UNDERNEATH RIGHT ENTRANCE REGION OF A 120KT UPPER JET. ELEVATED INSTABILITY SUNDAY MORNING (SHOWALTER INDICES ~ -2 DEG C) WILL GRADUALLY TRANSITION TO SFC-BASED INSTABILITY AS THE WARM SECTOR SURGES NORTHWARD (BL LI -2 TO -3 DEG C) ACROSS SRN AND ERN MS. WIDESPREAD DEEP CONVECTION SHOULD DEVELOP BY SUNDAY AFTERNOON ACROSS MUCH OF THE AREA. THERE MAY BE A SMALL WINDOW FOR DISCRETE SFC-BASED TSTMS SUNDAY AFTERNOON IN THE HBG-LAUREL AREA AS ENVIRONMENTAL SHEAR BECOMES VERY IMPRESSIVE (0-1KM 35-40KTS, 0-6KM ~45KTS). HOWEVER...EXPECT THE PRIMARY CONVECTIVE MODE WILL BECOME ORGANIZED AND LINEAR. WHILE 2-8 KM SHEAR VECTORS ARE FORECAST TO BE NORMAL TO THE APPROACHING COLD FRONT SUGGESTING CELLULAR CONVECTION...THEY ARE ALSO FORECAST TO BE QUITE WEAK (< 8KTS). THIS COMBINED WITH STRONG FORCING AND LOW-LEVEL CONVERGENCE IMPLIES THE DEVELOPMENT OF A LINEAR CONVECTIVE SYSTEM COMPRISED OF OCCASIONAL BOWS AND LEWPS AND ISOLATED TORNADOES. GIVEN THE STRENGTH OF THE LOW-LEVEL WIND FIELDS...EXPECT THAT SIGNIFICANT WIND DAMAGE COULD OCCUR OVER PORTIONS OF CNTRL/ERN MS WITH THE GREATEST RISK BEING ALONG THE INTERSTATE 59 CORRIDOR FORM HBG TO MEI...AND SLIGHTLY LOWER RISK NEAR AND SOUTHEAST OF THE NATCHEZ TRACE. THE PAST FEW RUNS OF THE GFS HAVE BEEN CONSISTENT IN THIS PORTRAYAL. HEAVY RAINFALL IS ALMOST A CERTAINTY WITH TOTAL AMOUNTS OF TWO TO FOUR INCHES EXPECTED AREA-WIDE...ALTHOUGH LOCATIONS EAST OF THE MS RIVER APPEAR TO HAVE THE GREATEST POTENTIAL TO GET LOCALLY HEAVIER TOTALS WHERE DEEP CONVECTION CAN PERSIST LONGEST. THE PROGRESSIVE NATURE OF THE SYSTEM SHOULD KEEP THE AREA FROM EXPERIENCING SIGNIFICANT FLOODING. IT DOES NOT LOOK LIKE RAINFALL WILL WE WILL HAVE ANY SIGNIFICANT FLOODING PROBLEMS. WILL CONTINUE TO CONVEY SEVERE WEATHER AND HEAVY RAIN RISKS IN THE HWO AND GRAPHICAL PRODUCTS. BEYOND MONDAY...THE PATTERN LOOKS TO STAY ACTIVE AS A LONGWAVE TROUGH OVER THE WRN CONUS IS STRENGTHENED BY ADDITIONAL SHORTWAVE ENERGY DIVING SWD INTO THE BASE OF THE TROUGH. THE GFS AND ECMWF HAVE BETTER AGREEMENT IN THE FORECAST DETAILS...SHOWING THE NEXT FRONTAL RAIN/TSTM EVENT SETTING UP IN THE WED-THU TIME FRAME...AND THEN AGAIN DURING THE WEEK`S END. TEMPERATURES MAY FLUCTUATE QUITE A BIT...MORE THAN INDICATED BY MEX MOS GUIDANCE...GIVEN THE OSCILLATING POLAR FRONTAL BOUNDARY OVER THE LOWER MS VALLEY AND VERY STRONG RIDGE OVER THE FL PENINSULA. DEPENDING ON HOW MUCH RAINFALL IS RECEIVED IN THE NEXT FEW DAYS...FLOODING COULD BECOME A CONCERN IN THIS SORT OF TROUGH-TO-RIDGE PATTERN. HAVE THEIR OWN IDEAS ABOUT THE FORECAST DETAILS WITH THE GFS HOLDING THE NEXT STORM SYSTEM OFF UNTIL NEXT WEEKEND AND THE ECMWF INSISTING ON AN EARLIER ARRIVAL. IN ANY CASE...WE COULD SEE THE DEVELOPMENT OF A STORMY TROUGH-TO-RIDGE PATTERN AS THE WEEK PROGRESSES. /EC/ && .AVIATION... MOST AREAS CAN COUNT ON AT LEAST VFR MID LEVEL CEILINGS OF 6-9K FEET WITH LIGHT RAIN STILL POSSIBLE ACROSS SRN THIRD OF MS THROUGH 15Z. THE SHOWERS WILL END FROM THE NORTHWEST BEFORE 16Z WITH CLOUDS SLOWLY BREAKING FROM N TO S BY 20Z. N SURFACE WINDS WILL PERSIST AT 10-15KTS MUCH OF DAY WITH SOME HIGHER GUSTS AT TIMES. TEMPORARY CLEARING OF CLOUDS FROM N TO S EXPECTED THIS EVENING WITH NE WINDS 5-10KTS. MORE CIRRUS SHOULD ARRIVE LATE TONIGHT. /40/ && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM: 40 LONG TERM: EC ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 344 PM CST THU NOV 22 2007 .DISCUSSION... PERSISTENT STRATUS/STRATOCUMULUS DECK HAS KEPT TEMPERATURES DOWN THIS AFTERNOON...AND WITH COLD ADVECTION CONTINUING TONIGHT...IT LOOKS LIKE FORECAST TEMPS IN THE LOW TO MID 20S ACROSS MOST OF THE CWFA WILL BE SPOT ON. CLOUDS SHOULD STICK IN MOST AREAS THROUGH 06Z...THEN CLEAR OUT FROM THE NORTHWEST ACROSS THE AREA THROUGH 12-15Z FRIDAY. COOL AND QUIET WEATHER SHOULD CONTINUE INTO THE WEEKEND...WITH HIGHER CLOUDS STREAMING INTO THE AREA ON SATURDAY AS A SHORTWAVE AND ASSOCIATED MID/UPPER LEVEL MOISTURE TRAVERSES THE MIDWEST. SUNDAY INTO MONDAY IS STILL LOOKING PRETTY INTERESTING AS A 500MB CUTOFF LOW EJECTS FROM THE SOUTHWESTERN US INTO THE SOUTHERN PLAINS AND THE MID-MISSISSIPPI VALLEY. THE GFS AND ECMWF HAVE COME INTO PRETTY DECENT AGREEMENT WITH THE HANDLING OF THIS SYSTEM...SPREADING A LARGE AREA OF QPF OUT AHEAD OF THE SYSTEM ACROSS SOUTHERN MISSOURI ON SUNDAY NIGHT AND OUT ACROSS MUCH OF THE REST OF THE AREA ON MONDAY. I HAVE INCREASED POPS A BIT FOR THOSE PERIODS SINCE THE MODELS HAVE COME INTO BETTER ALIGNMENT...BUT THE 22/00Z GFS ENSEMBLE RUN STILL HOLDS THE STORM BACK A BIT IN THE SOUTHERN PLAINS...SO I HAVEN`T INCREASED TO LIKELY POPS YET. WOULD LIKE TO LET THE NAM CHEW ON THIS SYSTEM FOR A CYCLE OR TWO BEFORE RAISING POPS INTO LIKELY CATEGORY. THERMAL PROFILES ARE INDICATING THAT THE PRECIPITATION SHOULD BE ALL RAIN ACROSS THE CWFA...POSSIBLY ENDING AS SNOW LATE MONDAY AFTERNOON OR EVENING. BUT WE`RE PRETTY CLOSE TO THE LINE. WOULDN`T BE SURPRISED TO SEE SUBSEQUENT MODEL RUNS FLIP-FLOP THE PRECIPITATION TYPE BETWEEN RAIN AND SNOW A FEW TIMES BEFORE THE STORM HITS. KEPT PRECIP TYPE ALL RAIN FOR THIS PACKAGE SINCE THAT`S WHAT THE DATA INDICATES. AFTER THE STORM EXITS THE REGION ON MONDAY NIGHT...TUESDAY AND WEDNESDAY LOOK TO BE DOMINATED BY ANOTHER COOL HIGH PRESSURE SYSTEM. THE NEXT POTENTIAL STORM SYSTEM FOR THE MID-MISSISSIPPI VALLEY COULD AFFECT THE AREA AS EARLY AS THURSDAY...BUT MIDRANGE MODELS ARE DIFFERING ONCE AGAIN ON TIMING AND STRENGTH WITH THIS SECOND SYSTEM SO HAVE LEFT FORECAST DRY FOR NOW. CARNEY && .AVIATION... FOR THE 18Z TAFS...AFTER CONSULTATION WITH OTHER OFFICES AND CWSU LOOKS LIKE THE CLOUDS WIL HOLD ON LONGER THE EARLIER FORECAST. RUC KEEPS HIGH 850 MOISTURE OVR THE NRN THIRD OF THE CWA THROUGH 03Z WITH IT MOVING SOUTH. COU SHOULD BE THE FIRST TO IMPORVE WITH VFR POSSIBLE BY 03S. HAVE KEPT MVFR CLOUD DECK FOR UIN UNTIL 06Z AND STL AND SUS UNTIL 06Z. JPK && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 1225 PM CST THU NOV 22 2007 .DISCUSSION... THE 00Z SHORT-TERM MODELS (TIL SUNDAY)...ARE IN DECENT AGREEMENT ON MASS FIELDS THRU THE NEXT 36HRS...BUT THEN DIVERGE ON HANDLING OF BREAKAWAY ENERGY FROM NEW SYSTEM OVER THE SWRN CONUS...AND HOW IT WILL MERGE WITH/BECOME IN-PHASE WITH NRN STREAM ENERGY. FURTHER DIFFERENCES ARISE...PRIMARILY WITH TIMING...ON STRONG SYSTEM TO IMPACT THE AREA EARLY NEXT WEEK...AS THE SWRN CONUS SYSTEM EJECTS NEWD TOWARDS THE LOWER-MID MS VALLEY. IN THE MEANTIME...LONGWAVE H500 TROF DOMINATING MUCH OF THE CONUS THIS THANKSGIVING DAY 2007 WILL PERSIST FOR ABOUT ANOTHER 24-36HRS AND THEN RECEDE WHILE SHIFTING EWD DURING THE HOLIDAY WEEKEND. A TRANSITIONAL...YET ACTIVE...PATTERN WILL THEN TAKE SHAPE FOR NEXT WEEK. AT THE SURFACE...PRESSURE GRADIENT WILL WEAKEN TODAY RESULTING IN GRADUAL ABATEMENT OF THE WIND SPEEDS WHILE WEAK CYCLONIC FLOW BECOMES ANTI-CYCLONIC THIS MORNING...WHICH SHOULD DIMINISH OR END THE FLURRIES. P-TYPE THIS MORNING AFTER 12Z...IF ANY FALLS...SHOULD BE OVERWHELMINGLY FLURRIES WITH CLOUD TOPS EXPECTED TO REACH TO -10C AND BE ABLE TO TAP INTO SOME ICE NUCLEI. THIS IS IN LIEU OF DRIZZLE OR FREEZING DRIZZLE. OVERALL THOUGH...PCPN COVERAGE WILL BECOME MORE AND MORE SPARSE AS ANTI- CYCLONIC FLOW BUILDS IN FROM STRONG CANADIAN HI PRES. TEMP RECOVERY TODAY WILL BE RATHER MEAGER GIVEN EXTENSIVE LO CLOUD ALREADY IN PLACE...AND REINFORCEMENTS ARE MOVING S FROM IA. LOCAL CLIMATOLOGY SUGGESTS ABOUT 5F. THIS SUPPORTS FORECASTING AOB THE COOLEST MOS...AND SEEMS REASONABLE. STRENGTH OF COLD AIRMASS SETTLING INTO THE AREA TONIGHT SUPPORTS A MIN TEMP FORECAST AOB THE COLDEST MOS...ESPECIALLY WITH CLEARING SKIES EXPECTED. MODELS DIVERGE ON HANDLING OF SYSTEM ON SATURDAY...WITH ITS TWO DISTINCT PARTS. THE FIRST PART WILL BE A BREAKAWAY PIECE OF THE SWRN CONUS SYSTEM THAT WILL TEMPORARILY BE CUTOFF FROM THE MAIN FLOW. MODELS ARE IN GOOD AGREEMENT ON TIMING...LATE FRIDAY NIGHT AND INTO SATURDAY MORNING...BUT THIS IS ONLY WITH THE MODELS THAT SHOW THIS PIECE OF ENERGY...NOT ALL DO. TWO SHORTWAVES WILL HELP TO CREATE CUTOFF LO OVER THE SWRN CONUS INITIALLY...AND GFS HANDLING OF BREAKWAY ENERGY WITH THE FIRST PIECE SEEMS MORE REASONABLE...AND NOTICED THAT THE 06Z NAM HAS COME MORE ON BOARD WITH THE GFS WHEREAS THE 00Z DID NOT. TWO MAIN FORCING MECHS TO CONSIDER...WITH UPPER LEVEL DIVERGENCE WITH LEFT EXIT OF H300 SPEED MAX AND MID-LEVEL Q-VEC CONVERGENCE...BUT THESE BECOME OUT OF PHASE BEFORE THEY MOVE TO FAR INTO MO FROM THE W. AND BECAUSE OF THIS...THE ASSOCIATED LIGHT PCPN WITH THIS WILL FALL APART BEFORE IT GETS TO THE FA AS DRY AIR ENTRENCHED AT THE LO LEVELS WILL DELIVER THE FINAL BLOW. CANNOT FULLY RULE OUT A SNOW FLURRY OR SPRINKLE...BUT LOW ENOUGH PROB TO NOT MENTION AT THIS TIME. SECOND PART OF THE SATURDAY SYSTEM WILL BE MERGING OF NRN STREAM ENERGY LATER SATURDAY AFTERNOON AND EARLY EVENING WITH BRIEF APPEARANCE OF ANOTHER SHOT OF UPPER LEVEL DIVERGENCE FROM RIGHT ENTRANCE REGION OF H300 SPEED MAX AND ANOTHER AREA OF MID LEVEL Q-VEC CONVERGENCE...BUT THE RAPIDLY EWD MOVING FORCING MECHS AND THE DRY AIR UNDERLYING THEM SHOULD PREVENT NEW PCPN DEVELOPMENT... ALTHOUGH AGAIN A SPRINKLE COULD NOT FULLY BE RULED OUT...GENERALLY S OF THE I-70 CORRIDOR. MOS BLEND USED ON MAX TEMPS FOR FRIDAY...AND FAVORED THE COOLER END OF MOS FOR SATURDAY WITH EXPECTED CLOUD COVER. ANOTHER...MUCH STRONGER SYSTEM...TO IMPACT THE AREA SOME TIME EARLY NEXT WEEK...AS THE SWRN CONUS CUTOFF GETS EJECTED THRU THE SRN PLAINS AND THEN TURNS NEWD THRU THE LWR-MID MS VALLEY. TIMING ISSUES ABOUND...WITH A ROUGH CENTERING ON MONDAY. P-TYPE EXPECTED TO BE LIQUID WITH THIS SYSTEM. TES && .AVIATION... FOR THE 18Z TAFS...AFTER CONSULTATION WITH OTHER OFFICES AND CWSU LOOKS LIKE THE CLOUDS WIL HOLD ON LONGER THE EARLIER FORECAST. RUC KEEPS HIGH 850 MOISTURE OVR THE NRN THIRD OF THE CWA THROUGH 03Z WITH IT MOVING SOUTH. COU SHOULD BE THE FIRST TO IMPORVE WITH VFR POSSIBLE BY 03S. HAVE KEPT MVFR CLOUD DECK FOR UIN UNTIL 06Z AND STL AND SUS UNTIL 06Z. JPK && .PRELIMINARY POINT TEMPS/POPS... ST LOUIS 39 26 42 30 / 5 0 0 5 QUINCY 35 20 40 25 / 5 0 0 5 COLUMBIA 37 20 41 27 / 0 0 0 10 JEFFERSON CITY 38 20 41 27 / 0 0 0 10 SALEM 39 24 42 25 / 10 5 0 5 FARMINGTON 39 21 40 24 / 5 0 0 10 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 959 AM EST THU NOV 22 2007 .SYNOPSIS... LOW PRESSURE WILL MOVE ACROSS THE REGION TODAY...BRINGING WITH IT SOME RAIN SHOWERS. THIS AFTERNOON...AS THE LOW BEGINS TO PULL AWAY FROM THE REGION...MUCH COLDER AIR WILL FILTER IN...CHANGING ANY REMAINING PRECIPITATION TO SNOW BY MID TO LATE AFTERNOON ACROSS CENTRAL NEW YORK...WITH A FEW FLAKES POSSIBLE INTO NORTHEAST PENNSYLVANIA BY THIS EVENING. LAKE EFFECT SNOW WILL DEVELOP BEHIND THE FRONT TONIGHT, AND BRING A FEW INCHES OF SNOW TO UPSTATE NY. && .NEAR TERM /TODAY/... HAVE UPDATED THIS MORNING TO ACCOUNT FOR RELATIVE LACK OF PRECIPITATION ACROSS THE CWA...WITH FRONTAL BOUNDARY STILL LOCATED OVER THE NORTHWESTERN HALF OF THE CWA...WITH THE PRIMARY BATCH OF SHOWERS WELL NORTH AND WEST OF THIS BOUNDARY...COLLOCATED WITH A GOOD BAND OF MID LEVEL FN CONVERGENCE. SURFACE LOW IS CURRENTLY LOCATED NEAR BRADFORD AND SHOULD TRACK TOWARDS ELMIRA BY NOON...AND THEN NORTHEAST TOWARDS COOPERSTOWN BY MID AFTERNOON. TEMPERATURES HAVE REMAINED ABOVE FREEZING THROUGHOUT THE CWA...WITH NORTHERN ONEIDA COUNTY BEING THE CLOSEST TO ANY PTYPE ISSUES AT THE MOMENT. TEMPS NORTH OF THE BOUNDARY FROM KITH TO KSYR TO KRME HAVE BEEN STEADY THIS MORNING...AND SEE NO REASON FOR MUCH COOLING TO OCCUR UNTIL THE LOW PASSES NORTH OF YOUR LATITUDE. THEREFORE...HAVE DELAYED CHANGEOVER TO SNOW...WITH ALL LOCATIONS EXPECTED TO REMAIN RAIN THROUGH ABOUT 1 PM. AFTER THIS POINT...EXPECT THE CHANGE TO SNOW TO REACH AN ELM-ITH-RME LINE BY ABOUT 3-4 PM...BGM NEAR OR A LITTLE AFTER SUNSET...AND AVP DURING THE EVENING. THE OTHER QUESTION TODAY WILL BE...IS THERE ANY PRECIP LEFT WHEN IT BECOMES COLD ENOUGH TO SNOW. REGIONAL RADAR SUGGESTS VERY LITTLE BEHIND THE DEVELOPING LOW...INCLUDING LOCATIONS LIKE KBUF...WHICH ARE NEARING FREEZING AT THIS HOUR. THEREFORE...FEEL THAT THERE WILL BE LITTLE IF ANY IN THE WAY OF ACCUMULATIONS THIS AFTERNOON WITH NOT MUCH QPF TO SPEAK OF. HAVE KEPT LIKELY POPS NORTH OF THE NY/PA BOARDER TO ACCOUNT FOR THE FACT THAT THIS FRONT WILL BE GETTING A GOOD BOOST FROM STRENGTHENING UPPER DYNAMICS AS THE LOW PRESSURE SYSTEM GETS ITS ACT TOGETHER OVERHEAD. HOWEVER...HAVE CUT BACK POPS TO SCATTERED OVER NE PA AND HAVE A FEELING THAT SOME LOCATIONS MAY MAKE IT THROUGH THE DAY DRY. HAVE CONTINUED TO FOLLOW HOURLY TEMP DEPICTION OF OUR LOCAL WORKSTATION WRF RUN...BUT HAVE NUDGED IT TO THE LATEST RUC GUIDANCE WHICH HOLDS OFF THE COLD AIR JUST A BIT LONGER. UPDATED ZONES/GRIDS ARE ON THE STREET. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... 310-FLOW SETS UP BEHIND THE FRONT, WITH A MODEST SNOW GROWTH LAYER, DECENT LAKE CAPE, AND FAVORABLE SHEAR. WE EXPECT A BAND TO FORM AND EXTEND INTO ONONDAGA AND MADISON COUNTIES, WITH PERIPHERAL ACTIVITY IN THE SURROUNDING COUNTIES. DIRECTLY UNDER THE BAND, A 1 TO 3 INCH ACCUMULATION IS POSSIBLE BY EARLY FRIDAY. THE FLOW SHIFTS A BIT ON FRIDAY TO A MORE 320-TYPE FLOW. OUR SIMILAR SOUNDINGS DATABASE SHOWS THIS TYPE OF FLOW TENDS TO WIDEN OUT THE ACTIVITY, AND LESSEN THE INTENSITY TOO, DUE TO A POOR FETCH. THERE COULD BE SOME ENHANCEMENT DOWNWIND OF THE FINGER LAKES. A GENERALIZED INCH OR SO OF SNOW IS FORECAST ACROSS MUCH OF UPSTATE NY AND THE NORTHERN TIER OF PA. AS HIGH PRESSURE APPROACHES, THE FLOW WILL BRIEFLY SHIFT LIGHT ACTIVITY INTO NORTHERN ONONDAGA AND ONEIDA COUNTIES FRIDAY NIGHT. ON SATURDAY, HIGH PRESSURE WILL END THE LAKE ACTIVITY AND BRING FAIR WEATHER. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... SHRT WV LIFTS NEWRD IN THE SW FLOW AND PUSHES PCPN INTO THE AREA LATE MON OR EARLY TUE. TEMPS MRGNL BUT IT COULD BE COLD ENUF FOR SOME MIXED PCPN AT NGT...OTRW GNRLY LOOKING AT A WET SCENARIO WITH THIS SRN SYSTEM. GOOD PUSH OF COLD AIR BHD THE SYSTEM BEGINNING WED WITH SCT LE SNOWS SURE TO FOLLOW. GMOS TEMP GUID WAS CONSISITENT SO WAS FLWD. MINOR ADJUSTMENTS WERE MADE TO THE OTR FIELDS. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... FNTL BNDRY CUTS THRU THE FCST AREA THIS MRNG WITH VAST DFRNCS IN WX AND FLIGHT CONDITIONS. IN THE COLD AIR...STATIONS GNRLY IFR OR LIFR WITH STATIONS IN THE WRM SECTOR VFR. BNDRY WILL BEGIN TO PUNGE SOUTH BETWEEN 15Z AND 18Z FLWG A WV MVG NEWRD AND WILL BRING MUCH COLDER AIR INTO THE AREA. THIS COLDER AIR WILL GNRLY BE DRYER AND ALLOW CIGS TO RISE...XCPT IN SCT SNOW SHWRS. LE SNOW SHWRS AND MVFR CIGS AND VSBYS CUD LINGER THRU THE NGT IN ALL STATION OTR THAN AVP. XTNDD PD WILL BRING GNRL VFR CONDS WITH HIPRES. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJP NEAR TERM...JMA SHORT TERM...DJP LONG TERM...DGM AVIATION...DGM ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1235 PM EST THU NOV 22 2007 .SYNOPSIS... A COLD FRONT WILL PUSH THROUGH THE CAROLINAS LATE THIS AFTERNOON FROM WEST TO EAST REACHING THE COASTAL WATERS THIS EVENING. HIGH PRESSURE WILL BUILD ACROSS THE AREA FROM THE NORTHWEST FRIDAY THROUGH SATURDAY. A COASTAL TROUGH WILL DEVELOP ACROSS THE SOUTHEAST COAST SATURDAY NIGHT INTO SUNDAY AS A STORM SYSTEM TAKES SHAPE WHICH SHOULD AFFECT OUR AREA EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 9 AM THURSDAY...FIRST LIGHT BATCH OF PRECIPITATION HAS DISSIPATED OVER SOUTHEAST NORTH CAROLINA AND ANOTHER VERY LIGHT PATCH OF RAIN IS MOVING INTO SOUTHWEST PORTION OF COUNTY WARNING AREA. IT APPEARS THAT CONVECTION OVER SOUTHEASTERN GEORGIA AND NORTHERN FLORIDA HAS HINDERED THE MOISTURE FLOW INTO THE AREA FOR THIS MORNING. THERE IS A OPEN SLOT FOR MOISTURE BEHIND THIS CONVECTION AND THE 13 UTC RUC IS SHOWING A SHORTWAVE MOVING ACROSS WESTERN SOUTH CAROLINA WHICH IS ASSOCIATED WITH AN AREA OF SHOWERS AND ISOLATED THUNDERSTORMS. THE RUC INDICATES THE LIFT WILL SHIFT TO THE COAST THIS AFTERNOON SO THIS MAY BE OUR BEST CHANCE OF RAIN. THE FRONT IS PROGGED TO MOVE ACROSS THE AREA TONIGHT AND THE LOCAL 4KM WRF SHOWS FRONT MAKING IT TO THE COAST BY 06 UTC. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 AM THURSDAY...HIGH PRESSURE WILL BUILD IN FRIDAY INTO SATURDAY WITH COLD DRY AIR IN PLACE THROUGH EARLY SATURDAY. MAX TEMPS WILL BE A GOOD 10 DEGREES COOLER THAN PREVIOUS DAYS IN A BRISK NORTHERLY WIND. THE COLDEST WEATHER OF THIS WEEK WILL PREVAIL FRI NIGHT WITH TEMPS DIPPING DOWN TO THE FREEZING MARK. SATURDAY WILL START OUT COLD...BUT BY SAT EVENING A TRANSITION WILL OCCUR AS WINDS SHIFT AROUND TO THE SOUTH AT LOW LEVELS BRINGING IN WARMER MOISTER AIR THROUGH SAT NIGHT. SHOULD SEE AN INCREASE IN CLOUDS LATE SATURDAY WITH AN INCREASING CHC OF PCP. PCP WATER VALUES WILL BOTTOM OUT EARLY SAT AT LESS THAN A QUARTER OF AN INCH...BUT WILL RISE RATHER RAPIDLY THROUGH THE DAY REACHING AROUND AN INCH BY MIDNIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 3 AM THURSDAY...AS HIGH PRESSURE MOVES OFF THE MID ATLANTIC COAST LATE SATURDAY INTO SUNDAY A COASTAL TROUGH SETS UP KEEPING A LIGHT NORTHEAST FLOW AT THE SFC..BUT A RETURN FLOW SETS UP AT LOWER LEVELS BRINGING GULF MOISTURE RAPIDLY BACK INTO THE LOCAL AREA...AS A LOW PRESSURE SYSTEM DEVELOPS IN THE GULF. LOW LEVEL WINDS WILL INCREASE THROUGH SUNDAY TO AROUND 20 TO 30 KTS. THE LOW PRESSURE SYSTEM DEEPENS AS IT MOVES RAPIDLY OFF TO THE NORTH NORTHEAST TOWARD THE NEW ENGLAND DRAGGING A WARM FRONT ACROSS THE AREA ON MONDAY WITH THE COLD FRONT FOLLOWING ON TUESDAY NIGHT INTO WED. OVERALL CLOUDS SHOULD INCREASE THROUGH EARLY SUNDAY AND REMAIN THROUGH EARLY NEXT WEEK WITH INCREASING CHC OF PCP AND POTENTIAL FOR SOME DESCENT QPF UNTIL COLD FRONT PASSES ON TUESDAY. WITH COASTAL TROUGH TO THE EAST AND COOL WEDGE OF HIGH PRESSURE TO THE WEST ON SUNDAY...TEMPS WILL BE TRICKY. FOR NOW WENT WITH FAIRLY TIGHT GRADIENT WITH WARMER TEMPS ALONG THE COAST TO AROUND 60 AND COOLER TEMPS INLAND...REMAINING IN THE LOWER 50S. COASTAL TROF PROGGED TO PUSH INLAND SUN NIGHT AS LOW PRESSURE TAKES SHAPE ALONG THE GULF COAST...WITH MUCH WARMER AIR FOR MONDAY. COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT INTO WED. COOLER AND DRIER WEATHER WILL FOLLOW FOR MID WEEK AS STRONG HIGH PRESSURE BUILDS INTO THE AREA. && .AVIATION /18Z THURSDAY THROUGH MONDAY/... COLD FRONT APPROACHING THE WESTERN CAROLINAS IS EXPECTED TO CROSS THE INLAND TAF SITES AROUND 01 UTC AND APPROACH THE COASTAL SITES AROUND 14 UTC. CEILING AND VISIBILITIES ARE EXPECTED TO ONLY LOWER TO MVFR CONDITIONS. WINDS ARE EXPECTED TO INCREASE AHEAD OF FRONTAL PASSAGE WITH A QUICK WIND SHIFT. HIGH PRESSURE SHOULD BRING VFR CONDITIONS FRIDAY THROUGH SATURDAY. A GULF COAST STORM SYSTEM AND A COASTAL TROUGH JUST OFFSHORE WILL LEAD TO THE DEVELOPMENT OF LOW CLOUDS AND WIDESPREAD RAIN SUNDAY INTO MONDAY. IFR CEILINGS AND/OR VISIBILITIES ARE EXPECTED TO FOR SUNDAY AND MONDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 9 AM THURSDAY...LATEST BUOY OBSERVATIONS SHOWING SOUTHWEST WINDS OF 15 KNOTS WITH FRYING PAN SHOALS NEAR 20 KTS. SEAS ARE RUNNING 3 TO 4 FT AT THE ONSLOW BAY BUOYS WITH 5.5 FT REPORTED AT FRYING PAN SHOALS. STILL HAVE FRONTAL BOUNDARY APPROACHING THE COAST AROUND 06 UTC. LATEST RUC 10 METER WINDS INDICATES A LINE OF INCREASED WINDS JUST AHEAD OF THE FRONT. THE WINDS ARE EXPECTED TO 20 TO 25 KNOTS AND GUSTS OF 30 TO 35 NORTH OF CAPE FEAR AND GUST OF 25 TO 30 TO THE SOUTH. WITH THIS LATEST RUN THE WIND SPEEDS ARE EXPECTED TO REACH SMALL CRAFT CONDITIONS FOR ALL OF OUR WATERS SO HAVE ADDED MARINE ZONE FROM MURRELLS INLET TO THE SOUTH SANTEE RIVER IN THIS UPDATE. SHORT TERM/FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 AM THURSDAY...OFFSHORE FLOW WILL KNOCK DOWN SEAS TO BELOW SIX FEET FRIDAY MORNING BRINGING SEAS TO BELOW SCA. WINDS WILL REMAIN 15-20 KNOTS WITH A FEW HIGHER GUSTS IN COLD AIR ADVECTION FRIDAY THROUGH FRIDAY NIGHT AS HIGH PRESSURE BUILDS IN. LONG TERM/SUNDAY THROUGH MONDAY/... AS OF 3 AM THURSDAY...COASTAL TROUGH SETS UP ON SUNDAY INTO MONDAY. FORECAST HIGHLY DEPENDENT ON THE POSITION OF THE COASTAL TROF...BUT WINDS SHOULD REMAIN NE THROUGH SUNDAY. ONCE THE COASTAL FRONT/TROF LIFTS NORTH SUNDAY NIGHT...THE WINDS WILL VEER AROUND TO THE SOUTH FOR MONDAY. INCREASING SOUTHERLY WINDS WILL HELP TO BUMP SEAS UP MONDAY INTO POSSIBLE SCA. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EST FRIDAY FOR AMZ254-256. SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR AMZ250-252. && $$ SYNOPSIS...RGZ NEAR TERM...HAWKINS SHORT TERM...RGZ LONG TERM...RGZ AVIATION...HAWKINS nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 313 AM EST THU NOV 22 2007 .SYNOPSIS...A STRONG COLD FRONT WILL APPROACH FROM THE WEST ... CROSSING CENTRAL NORTH CAROLINA BY SUNSET. BELOW NORMAL TEMPERATURES WILL RETURN TO THE REGION FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... THE 07Z RUC MODEL IS INDICATING A SUBTLE JET STREAM LEVEL SHORT WAVE WITH SOME DIVERGENCE IN THE CURRENT PRECIPITATION AREA. THIS AREA LIFTS TO THE EAST NORTHEAST THIS MORNING. A QUICK TENTH INCH OF RAIN POSSIBLE WEST OF HIGH 49 IN THE WEST PIEDMONT AND NORTH OF HIGHWAY 64 IN THE EAST...WITH GENERALLY LESSER AMOUNTS SOUTH. THERE HAS BEEN A RARE CLAP OF THUNDER WITH THESE SHOWERS. ANOTHER BATCH OF PRECIPITATION WILL MOVE IN WITH THE FRONT THIS AFTERNOON. RAINFALL AMOUNTS STILL EXPECTED TO BE RELATIVELY LIGHT AT AROUND ONE TENTH INCH. ONLY A SMALL CHANCE OF RAIN EAST OF INTERSTATE 95 AFTER SUNSET...WHICH SHOULD CLEAR QUICKLY. TEMPERATURES EITHER HOLDING STEADY BEFORE SUNRISE THIS MORNING OR MAKING A SLOW RISE AS CLOUDS INCREASE AND STEADY SOUTHWEST BREEZE CONTINUES. EXPECT SOME SUNSHINE AHEAD OF THE FRONT AND AFTERNOON HIGHS WILL BE TRICKY. A TEN DEGREE RISE AS CURRENTLY FORECAST LOOKS CLOSE. LOW LEVEL THICKNESSES PLUNGE LATE THIS AFTERNOON INTO TONIGHT. THE CURRENT FORECAST OF 35 TO 45 DEGREES NORTHWEST TO SOUTHEAST STILL LOOKS GOOD. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... THE FORECAST FOR THIS PERIOD IS LARGELY UNCHANGED. SURFACE HIGH PRESSURE WILL PUSH EAST BEHIND THE EXITING FRONT AND SETTLE OVER NORTH CAROLINA AND VIRGINIA SATURDAY. BELOW NORMAL HIGH TEMPERATURES OF 45 TO 55 ARE FORECAST WITH FRIDAY NIGHT LOWS BELOW FREEZING. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... SATURDAY NIGHT THROUGH MONDAY...THE MEDIUM RANGE BEGINS WITH COLD HIGH PRESSURE OVER THE AREA AND A COLD AIR DAMMING SCENARIO SETTING UP AS A WARM FRONT DEVELOPS TO OUR SOUTH WITH BROAD CONFLUENT SOUTHERLY FLOW OFF THE GULF AND THE ATLANTIC. THIS LEADS TO LARGE SCALE ISENTROPIC LIFT WITH VARYING AMOUNTS OF SATURATION AT VARIOUS TIMES AND LEVELS. POPS WILL BE INCREASING TO NEAR LIKELY WITH THIS PATTERN...BUT RAINFALL WILL BE LIGHT THROUGH SUNDAY NIGHT. THE ONSET OF PRECIPITATION SATURDAY NIGHT OR EARLY SUNDAY WITH DEW POINTS IN THE LOWER 20S MEANS SIGNIFICANT DIABATIC COOLING POTENTIAL AND TEMPERATURES HAVE BEEN FORECAST COLDER THAN GUIDANCE FOR MAXIMUMS...ESPECIALLY NORTHWEST SUNDAY. LOWS SATURDAY NIGHT 34 TO 40 AND HIGHS SUNDAY 41 TO 50. TEMPERATURES SHOULD HOLD NEARLY STEADY SUNDAY NIGHT. ON MONDAY...MODELS DIFFER WITH REGARD TO MOVEMENT OF DEEPENING LOW PRESSURE TO THE WEST OF THE APPALACHIANS AND DEGREE OF EROSION OF THE COLD AIR DAMMING OVER CENTRAL NORTH CAROLINA. THE FORECAST LEANS MORE TOWARD THE ECMWF AND CLIMATOLOGY IN KEEPING COLDER MOIST AIR OVER THE NORTHWEST PIEDMONT AND ONLY MODEST EROSION IN THE EASTERN AND SOUTHERN PIEDMONT PRIOR TO COLD FRONTAL PASSAGE MONDAY NIGHT. THE AIRMASS DESTABILIZES TO A MODERATE DEGREE WITH A SHARP TEMPERATURE CONTRAST LIKELY NEAR THE SURFACE AND ASSOCIATED WIND SHEAR NEAR A WARM FRONT. THIS WILL HAVE TO BE MONITORED IN SUCCEEDING MODEL RUNS FOR SEVERE WEATHER POTENTIAL. MAXIMUM TEMPERATURE CONTRAST MONDAY MAY STRETCH FROM 50 NORTHWEST TO NEAR 70 SOUTHEAST. MONDAY NIGHT THROUGH WEDNESDAY... THE COLD FRONT PASSES MONDAY NIGHT FOLLOWED BY A MODIFIED PACIFIC AIRMASS BENEATH A RIDGING PATTERN TUESDAY AND WEDNESDAY. TEMPERATURES HAVE BEEN KEPT NEAR CLIMATOLOGY FOR NOW DUE TO UNCERTAINTY IN THE PROGRESSION OF THE PATTERN BY DAYS 6 AND 7. BUT CONSISTENCY WITH THIS PATTERN WOULD FAVOR TEMPERATURES RISING ABOVE NORMAL FOR THE MIDDLE OF NEXT WEEK. -RFG && .AVIATION /08Z THURSDAY THROUGH MONDAY/... SHOWERS DEVELOPING AHEAD OF AN APPROACHING COLD FRONT WILL SLOWLY PUSH EAST ACROSS THE REGION THIS MORNING REACHING INT AND GSO AFTER 09Z. SHOWER ACTIVITY THIS MORNING WILL BE LIGHT AND IS EXPECTED TO REDUCE VISIBILITIES TO ABOUT 4SM. CEILINGS SHOULD ALSO GRADUALLY APPROACH MVFR THIS MORNING FROM WEST TO EAST AS SKIES BECOME BKN-OVC030. THE MVFR CONDITIONS AND RAIN WILL TAKE LONGER TO REACH RDU AND POINTS EAST AND WILL LIKELY NOT IMPACT RDU...RWI AND FAY UNTIL AFTER 12Z. GUSTY SW WINDS WILL ALSO DEVELOP AFTER DAYBREAK AS 30 KT WINDS IN THE LOWEST FEW THOUSAND FEET MIX DOWN TO THE SURFACE. ALSO EXPECT A FEW THUNDERSTORMS ACROSS THE ENTIRE REGION THIS AFTERNOON AS THE ATMOSPHERE DESTABILIZES AHEAD OF A STRONG APPROACHING COLD FRONT. MVFR TO OCCASIONAL IFR CONDITIONS ARE EXPECTED JUST AHEAD AND ALONG THE COLD FRONT. THE HEAVIEST RAIN AND THUNDERSTORMS ACTIVITY WILL OCCUR ALONG THE FRONT WHICH WILL PUSH ACROSS CENTRAL NORTH CAROLINA FROM 18Z TO 00Z. GUSTY NORTHWEST WINDS WILL OCCUR IMMEDIATELY BEHIND THE FRONT WITH GUSTS AS HIGH AS 20 KNOTS. DRIER AIR WILL IMPROVE CONDITIONS THURSDAY NIGHT WITH JUST SOME MID AND HIGH CLOUDS EXPECTED ABOVE 5000 FEET. AS HIGH PRESSURE MOVES IN ON FRI AND SAT SKIES WILL REMAIN VFR. AN AREA OF LOW PRESSURE DEVELOPING IN THE GULF OF MEXICO WILL PUSH MOISTURE NORTH OVERRIDING THE COLD HIGH PRESSURE AT THE SURFACE. THIS WILL LIKELY RESULT IN WIDESPREAD IFR CEILINGS BY SUNDAY MORNING. CEILINGS SHOULD REMAIN IFR THROUGH THE DAY SUNDAY AND EVEN INTO MONDAY AS PERIODS OF RAIN MOVE THROUGH ALL OF CENTRAL NORTH CAROLINA. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ AVIATION...JO nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 904 AM EST THU NOV 22 2007 .SYNOPSIS... LOW PRESSURE LOCATED OVER NORTHWEST PENNSYLVANIA WILL CONTINUE MOVING TOWARD NEW ENGLAND PULLING MUCH COLD AIR INTO THE REGION. HIGH PRESSURE OVER THE CENTRAL PLAINS WILL SLOWLY BUILD INTO THE AREA ON FRIDAY AND THEN MOVE OVER THE OHIO VALLEY ON SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CHANGEOVER TO SNOW CONTINUES TO PROGRESS ESE ACROSS THE CWA AT THIS TIME. CHANGE NEAR CLE AND MFD AND SHOULD SPREAD RAPIDLY OVER THE REST OF THE AREA THROUGH NOON. DRIER PUNCH OF AIR AT MID LEVELS HAS CUT OFF MOST OF THE SIGNIFICANT PRECIP. THE ONLY SIGNIFICANT PRECIP CURRENTLY IS LAKE ENHANCED BAND OF MAINLY SNOW MOVING ESE ACROSS NORTH CENTRAL LAKESHORE COUNTIES. WILL USE UPDATE TO ADJUST FORECAST TO BACK OFF ON LIKELY OUTSIDE OF NORTH CENTRAL AND SNOW BELT COUNTIES FOR THIS AFTERNOON. REMAIN ON THE BUBBLE AS TO WHETHER A LAKE EFFECT SNOW ADVISORY IS NEEDED BUT GIVEN MAINLY LATE DAY AND TONIGHT EVENT INTO FRI MORNING CAN WAIT TIL 330 PM FORECAST TO ISSUE IF THINK ONE IS NEEDED. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... FOR TONIGHT HAVE CHANCE SNOW SHOWERS ACROSS MUCH OF THE FORECAST AREA. FOCUS WILL SHIFT TO LES DEVELOPING AS WINDS TURN NORTHERLY OVER THE LAKE TONIGHT. ALSO WITH FALLING TEMPS ANY SNOW THAT IS FALLING AFTER SUNSET WILL BEGIN TO STICK TO SURFACES AND IT IS AT THIS POINT ACCUMULATIONS WOULD BEGIN. GUIDANCE IS SUGGESTING THAT WINDS EARLY THIS EVENING WILL BE MAINLY FROM THE NORTH AND SUGGESTING THAT ANY LAKE EFFECT SNOW EARLY ON MIGHT BE MORE WIDESPREAD BUT DO NOT THINK ACCUMULATIONS WILL GET OUT OF CONTROL. FOCUS WILL BECOME LATE THURSDAY NIGHT INTO FRIDAY MORNING AS MODELS ARE SUGGESTING A LK HURON FETCH SETTING UP BRINGING SOME LE SNOWBANDS INTO PORTIONS OF NE OH AND THEN SHIFTING THEM INTO NW PA LATER ON FRIDAY. AT THIS TIME HAVE ACCUMULATIONS BELOW ADVISORY CRITERIA. SOME GOOD POINT ARE THE COLD H850S BUILDING OVER THE AREA BUT AT SAME TIME PLENTY OF DRY AIR BUILDING INTO THE AREA BEHIND THIS SYSTEM BY THUR NIGHT INTO FRIDAY. AT THIS TIME SEE SOME POSITIVES BUT ALSO QUITE A FEW NEGATIVES WHICH WOULD LIMIT CONFIDENCE AT THIS TIME OF AN AT LEAST ADVISORY EVENT. THERE IS THE CHC OF SOME LOCAL AMOUNTS ACROSS NE OH/NW PA SEEING ADVISORY CRITERIA BUT DO NOT SEE ANYTHING WIDESPREAD. FUTURE SHIFTS WILL ALSO CONTINUE TO EVALUATE THIS SITUATION. AS UPPER TROUGH PULLS AWAY AND HIGH PRESSURE BUILDS IN GRADUALLY WOUND DOWN LES ACROSS NE OH/NW PA INTO SATURDAY. BY THEN HIGH PRESSURE WILL BE BUILDING OVER OHIO VALLEY AND CONDITIONS WILL BE IMPROVING. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... HIGH PRESSURE RIDGE FOR SUNDAY NIGHT WILL WEAKEN AS LOW PRESSURE MOVES THROUGH THE AREA THROUGH TUESDAY. ECMWF AND GFS IN GENERAL AGREEMENT...LOCATION OF THE LOW ISSUES. IT DOES LOOK LIKE IT SHOULD BE ALL RAIN. TRYING TO DRY THINGS OUT ON TUESDAY BUT SOME PRECIPITATION COULD LINGER IN THE EXTREME EAST. IT TRIES TO GET COLD ON WEDNESDAY BUT WITH ALOT OF RIDGING WILL TRY TO KEEP THE SNOW BELT AND THE ENTIRE FORECAST AREA DRY. THIS WILL HAVE TO BE MONITORED. GUIDANCE TEMPERATURES GENERALLY OK. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... THE LOW IS NEAR YNG AT 12Z AND MOVING RAPIDLY NORTHEAST. USING THE 1300 1000-850 MB THICKNESS FOR THE SWITCH TO SNOW FROM THE RUC MODEL. THE PRECIPITATION IS REALLY LIGHT OVER MUCH OF THE AREA EXCEPT RIGHT NEAR THE LOW. SO ANY PRECIPITATION THIS MORNING WILL BE LIGHT RAIN BEFORE SWITCHING TO FLURRIES OR LIGHT SNOW SHOWERS. A LITTLE SLEET COULD OCCUR EAST OF TOL AND FDY THIS AM BUT IT WILL ONLY LAST FOR LESS THAN 30 MINUTES. THIS AFTERNOON WILL BEGIN THE TRANSITION TO LAKE EFFECT SNOW SHOWERS. MOISTURE IS LIMITED AND NOT A REAL STRONG SHORTWAVE. THE AIRMASS WILL CONTINUE TO DRY OUT TONIGHT WITH LAKE EFFECT SNOW SHOWERS CONTINUING IN THE EAST. MVFR OR LOWER THIS MORNING AND THEN SOME VFR TRYING TO DEVELOP OVER THE NORTHWEST IN THE AFTERNOON WITH MVFR CONTINUING EAST AND IFR IN SNOW SHOWERS. OUTLOOK...HIGH PRESSURE WILL BEGIN BUILDING IN FRIDAY AND SOME LAKE EFFECT WILL LINGER IN THE NORTHEAST PORTION OF THE FORECAST AREA. OTHERWISE IT WILL BE VFR. THE HIGH WILL MOVE EAST OVER THE WEEKEND AS A LOW PRESSURE MOVES TOWARD THE AREA FOR EARLY IN THE WORK. THE WEEKEND WILL BE VFR WITH SOME NON VFR CONDITIONS DEVELOPING ON MONDAY AS THE LOW MOVES INTO THE AREA. && .MARINE... THE STRONGEST WINDS WILL BE THIS MORNING AND EARLY AFTERNOON...THEY SHOULD STAY JUST BELOW GALE AND WILL OF COURSE CONTINUE THE SMALL CRAFT ADVISORY. WATER LEVELS SHOULD NOT GET HIGH ENOUGH IN THE NE FLOW THIS MORNING FOR ANY HIGH WATER CONCERNS ON THE WEST END OF THE LAKE. AS THE RIDGE BUILDS IN FRIDAY THE WINDS WILL DECREASE. AS THE HIGH MOVES EAST OVER THE WEEKEND A SOUTHWEST FLOW WILL DEVELOP. AS THE LOW MOVES UP FOR EARLY IN THE WEEK THE WINDS WILL INCREASE FROM THE WEST AND SMALL CRAFT ADVISORIES MAY BE NEEDED. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST FRIDAY FOR LEZ142>149. && $$ SYNOPSIS...ABE NEAR TERM...ABE SHORT TERM...ADAMS LONG TERM...KIELTYKA AVIATION...KIELTYKA MARINE...KIELTYKA oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 707 AM EST THU NOV 22 2007 .SYNOPSIS... LOW PRESSURE LOCATED OVER NORTH CENTRAL OHIO WILL CONTINUE MOVING NORTHEAST THIS MORNING ALONG THE COLD FRONT. ONCE LOW PRESSURE MOVES EAST INTO WESTERN PENNSYLVANIA AND THE COLD FRONT MOVES EAST OF THE AREA MUCH COLDER AIR WILL BUILD INTO THE REGION. HIGH PRESSURE FROM THE CENTRAL PLAINS WILL SLOWLY BUILD INTO THE AREA ON FRIDAY AND THEN MOVE OVER THE OHIO VALLEY ON SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... QUITE A VARIATION IN WEATHER EARLY THIS MORNING ACROSS THE FORECAST AREA. LOW PRESSURE CURRENTLY CENTERED JUST SOUTH OF WOOSTER ACCORDING TO 09Z ANALYSIS. TEMPERATURES AT THIS TIME JUST SOUTHWEST OF THE LOW CENTER IN THE LOWER 60S WHILE TEMPS JUST BEHIND THE LOW AT LOCATIONS SUCH AS MARION IN THE UPPER 40S. MOST GUIDANCE ON REASONABLE TRACK AT THIS TIME BUT MAY BE JUST A BIT FAST IN MOVING LOW INTO WESTERN PA OVER THE NEXT 6 HOURS OR SO. THE TIMING IS RATHER CRITICAL AS ALL MODELS ARE SHOWING QUICK CAA INTO THE AREA BEHIND THIS LOW LATER THIS MORNING WITH H850 TEMPS DROPPING WELL BELOW ZERO. TEMPS ACROSS NW ZONES EARLY THIS MORNING ALREADY IN UPPER 30S AT TOL AND FDY. RADAR SHOWING SWATH OF RAIN FROM BJJ TO MFD SW TO CMH AT THIS TIME. THIS WILL CONTINUE MOVING NE THROUGH THE FORECAST AREA OVER THE NEXT SEVERAL HOURS. WITH THAT KEPT AT LEAST LIKELY POPS ACROSS EASTERN AREAS TO GET RAIN OUT OF THE AREA. OTHER AREA OF PRECIP IS ACROSS MI AND NRN IN AT THIS TIME. EXPECTING THIS TO AFFECT NW ZONES EARLY THIS MORNING SO CONTINUED WITH LIKELY POPS OUT WEST ALSO. HOWEVER ONCE DEFORMATION PRECIP MOVES EAST THIS AFTERNOON BROUGHT POPS DOWN TO CHC ACROSS WESTERN AREAS. FOR THE VARIOUS PRECIP ACROSS THE AREA WORDED ZONES TO MENTION THE RAIN THIS MORNING CHANGING TO MIX RAIN AND SNOW SHOWERS THEN JUST SNOW SHOWERS ONCE COLDER AIR SETTLES OVERHEAD LATER THIS AFTERNOON. ALSO JUST MENTIONED TEMPS FALLING TODAY ACROSS AREA AS MT VERNON LAST HOUR WAS IN LOW 60S WHILE MARION WITH IN UPPER 40S. SIMPLY PUT TREND WILL BE FOR FALLING TEMPS TODAY AREAWIDE. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... FOR TONIGHT HAVE CHANCE SNOW SHOWERS ACROSS MUCH OF THE FORECAST AREA. FOCUS WILL SHIFT TO LES DEVELOPING AS WINDS TURN NORTHERLY OVER THE LAKE TONIGHT. ALSO WITH FALLING TEMPS ANY SNOW THAT IS FALLING AFTER SUNSET WILL BEGIN TO STICK TO SURFACES AND IT IS AT THIS POINT ACCUMULATIONS WOULD BEGIN. GUIDANCE IS SUGGESTING THAT WINDS EARLY THIS EVENING WILL BE MAINLY FROM THE NORTH AND SUGGESTING THAT ANY LAKE EFFECT SNOW EARLY ON MIGHT BE MORE WIDESPREAD BUT DO NOT THINK ACCUMULATIONS WILL GET OUT OF CONTROL. FOCUS WILL BECOME LATE THURSDAY NIGHT INTO FRIDAY MORNING AS MODELS ARE SUGGESTING A LK HURON FETCH SETTING UP BRINGING SOME LE SNOWBANDS INTO PORTIONS OF NE OH AND THEN SHIFTING THEM INTO NW PA LATER ON FRIDAY. AT THIS TIME HAVE ACCUMULATIONS BELOW ADVISORY CRITERIA. SOME GOOD POINT ARE THE COLD H850S BUILDING OVER THE AREA BUT AT SAME TIME PLENTY OF DRY AIR BUILDING INTO THE AREA BEHIND THIS SYSTEM BY THUR NIGHT INTO FRIDAY. AT THIS TIME SEE SOME POSITIVES BUT ALSO QUITE A FEW NEGATIVES WHICH WOULD LIMIT CONFIDENCE AT THIS TIME OF AN AT LEAST ADVISORY EVENT. THERE IS THE CHC OF SOME LOCAL AMOUNTS ACROSS NE OH/NW PA SEEING ADVISORY CRITERIA BUT DO NOT SEE ANYTHING WIDESPREAD. FUTURE SHIFTS WILL ALSO CONTINUE TO EVALUATE THIS SITUATION. AS UPPER TROUGH PULLS AWAY AND HIGH PRESSURE BUILDS IN GRADUALLY WOUND DOWN LES ACROSS NE OH/NW PA INTO SATURDAY. BY THEN HIGH PRESSURE WILL BE BUILDING OVER OHIO VALLEY AND CONDITIONS WILL BE IMPROVING. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... HIGH PRESSURE RIDGE FOR SUNDAY NIGHT WILL WEAKEN AS LOW PRESSURE MOVES THROUGH THE AREA THROUGH TUESDAY. ECMWF AND GFS IN GENERAL AGREEMENT...LOCATION OF THE LOW ISSUES. IT DOES LOOK LIKE IT SHOULD BE ALL RAIN. TRYING TO DRY THINGS OUT ON TUESDAY BUT SOME PRECIPITATION COULD LINGER IN THE EXTREME EAST. IT TRIES TO GET COLD ON WEDNESDAY BUT WITH ALOT OF RIDGING WILL TRY TO KEEP THE SNOW BELT AND THE ENTIRE FORECAST AREA DRY. THIS WILL HAVE TO BE MONITORED. GUIDANCE TEMPERATURES GENERALLY OK. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... THE LOW IS NEAR YNG AT 12Z AND MOVING RAPIDLY NORTHEAST. USING THE 1300 1000-850 MB THICKNESS FOR THE SWITCH TO SNOW FROM THE RUC MODEL. THE PRECIPITATION IS REALLY LIGHT OVER MUCH OF THE AREA EXCEPT RIGHT NEAR THE LOW. SO ANY PRECIPITATION THIS MORNING WILL BE LIGHT RAIN BEFORE SWITCHING TO FLURRIES OR LIGHT SNOW SHOWERS. A LITTLE SLEET COULD OCCUR EAST OF TOL AND FDY THIS AM BUT IT WILL ONLY LAST FOR LESS THAN 30 MINUTES. THIS AFTERNOON WILL BEGIN THE TRANSITION TO LAKE EFFECT SNOW SHOWERS. MOISTURE IS LIMITED AND NOT A REAL STRONG SHORTWAVE. THE AIRMASS WILL CONTINUE TO DRY OUT TONIGHT WITH LAKE EFFECT SNOW SHOWERS CONTINUING IN THE EAST. MVFR OR LOWER THIS MORNING AND THEN SOME VFR TRYING TO DEVELOP OVER THE NORTHWEST IN THE AFTERNOON WITH MVFR CONTINUING EAST AND IFR IN SNOW SHOWERS. OUTLOOK...HIGH PRESSURE WILL BEGIN BUILDING IN FRIDAY AND SOME LAKE EFFECT WILL LINGER IN THE NORTHEAST PORTION OF THE FORECAST AREA. OTHERWISE IT WILL BE VFR. THE HIGH WILL MOVE EAST OVER THE WEEKEND AS A LOW PRESSURE MOVES TOWARD THE AREA FOR EARLY IN THE WORK. THE WEEKEND WILL BE VFR WITH SOME NON VFR CONDITIONS DEVELOPING ON MONDAY AS THE LOW MOVES INTO THE AREA. && .MARINE... THE STRONGEST WINDS WILL BE THIS MORNING AND EARLY AFTERNOON...THEY SHOULD STAY JUST BELOW GALE AND WILL OF COURSE CONTINUE THE SMALL CRAFT ADVISORY. WATER LEVELS SHOULD NOT GET HIGH ENOUGH IN THE NE FLOW THIS MORNING FOR ANY HIGH WATER CONCERNS ON THE WEST END OF THE LAKE. AS THE RIDGE BUILDS IN FRIDAY THE WINDS WILL DECREASE. AS THE HIGH MOVES EAST OVER THE WEEKEND A SOUTHWEST FLOW WILL DEVELOP. AS THE LOW MOVES UP FOR EARLY IN THE WEEK THE WINDS WILL INCREASE FROM THE WEST AND SMALL CRAFT ADVISORIES MAY BE NEEDED. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST FRIDAY FOR LEZ142>149. && $$ SYNOPSIS...ABE NEAR TERM...ABE SHORT TERM...ABE LONG TERM...KIELTYKA AVIATION...KIELTYKA MARINE...KIELTYKA oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1023 AM CST THU NOV 22 2007 .UPDATE...CLOUDS WILL THICKEN THIS AFTERNOON IN ADVANCE OF A SHORT WAVE UPPER TROUGH TRACKING FROM SOUTHERN NEW MEXICO INTO WEST TEXAS. LOW LEVELS TO REMAIN DRY...BUT MID AND UPPER LEVEL FRONTAL ZONES STILL RESIDE OVER THE REGION...AND WILL SUPPORT ENHANCED UPWARD MOTION AS THE TROUGH APPROACHES. CLOUDS WILL INCREASE IN THICKNESS FROM NORTH TO SOUTH. FOR THIS REASON...HAVE DROPPED FORECAST HIGHS A FEW DEGREES NEAR THE RED RIVER AND INTO NORTH TEXAS. ALSO...RAISED POPS TO THE LIKELY CATEGORY FOR AREAS JUST SOUTH OF WICHITA FALLS AND VERNON. RADAR IMAGERY AND SURFACE OBS SUGGEST A FAIRLY BROAD AREA OF LIGHT PRECIP SOUTH OF A LUBBOCK TO ABILENE LINE...SPREADING EAST AND SLIGHTLY NORTH. NAM AND RUC MODELS ARE VERY SIMILAR IN BRINGING SATURATION DOWN TO AROUND 3 KM AGL...SOUTH OF HIGHWAY 287. THIS SHOULD BE SUFFICIENT TO GET LIGHT PRECIP TO THE GROUND. MAJORITY OF IT MAY FALL AS SNOW...BUT COULD SEE SOME WATER COATED SNOW GRAINS OR RAIN DROPS AS NEAR GROUND TEMPERATURES REMAIN JUST ABOVE FREEZING. NO TRAVEL PROBLEMS ANTICIPATED. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 44 28 46 31 / 0 10 10 30 HOBART OK 43 27 45 31 / 0 10 20 30 WICHITA FALLS TX 42 30 48 35 / 20 20 10 20 GAGE OK 44 21 37 26 / 0 10 30 50 PONCA CITY OK 42 26 42 31 / 0 0 20 40 DURANT OK 46 35 51 34 / 0 10 10 20 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ BURKE ok AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 933 PM CST FRI NOV 23 2007 .UPDATE... WATER VAPOR IMAGERY AND RUC H5 HEIGHT ANALYSIS INDICATE THAT INITIAL SHORTWAVE TROUGH IS NOW DIVING SOUTHWARD ACROSS SOUTHWESTERN COLORADO AND NORTHWESTERN NEW MEXICO...WHILE SECONDARY UPPER LEVEL LOW IS BEGINNING TO PINCH OFF ACROSS SOUTHWESTERN ARIZONA AND THE NORTHERN BAJA REGION AS EXPECTED COURTESY OF 90-100 KNOT UPPER JET DIVING SOUTHWARD ACROSS UTAH/NEVADA. SYNOPTIC SCALE LIFT IS BEGINNING TO INCREASE FROM SOUTHWESTERN TO CENTRAL NEW MEXICO AS EVIDENCED BY INCREASING PRECIPITATION RETURNS ON REGIONAL RADAR IMAGERY. THIS LIFT SHOULD BE INCREASING FROM THE GUADALUPE MOUNTAINS TO THE SOUTHEASTERN NEW MEXICO PLAINS AFTER 06Z...AND EXPECT SNOW TO INCREASE IN COVERAGE ACROSS THESE LOCATIONS DURING THIS TIME FRAME. HAVE DECIDED TO INCREASE OVERNIGHT POPS SIGNIFICANTLY TO THE LIKELY CATEGORY ACROSS THE ABOVE MENTIONED LOCATIONS...BETTER IN LINE WITH THE CURRENT WSW PRODUCT. ALSO INCREASED POPS GENERALLY ALONG AND NORTH OF THE I-20 CORRIDOR BEFORE 12Z. WE HAVE ALSO MADE SOME ADJUSTMENTS TO THE SATURDAY FORECAST. COLD FRONT SHOULD CONTINUE TO DIVE SOUTHWARD ACROSS THE CWA DURING THE DAY...AND LARGE SCALE LIFT SHOULD BECOME FOCUSED ACROSS THE CENTRAL AND SOUTHERN CWA AS THE DAY PROGRESSES AS THE UPPER LOW DEEPENS ACROSS NORTHERN MEXICO. AS SUCH...HAVE INCREASED POPS TO LIKELY CATEGORY ACROSS MOST LOCATIONS SATURDAY. FORECAST SOUNDINGS INITIALLY SUGGEST A MIX OF RAIN/SNOW SOUTH OF I-20 DURING THE MORNING...BUT DO SUPPORT ALL SNOW ACROSS VIRTUALLY THE ENTIRE CWA DURING THE AFTERNOON. WILL LET THE MID SHIFT DETERMINE IF A SNOW ADVISORY WILL BE NEEDED...INITIAL THOUGHTS ARE THAT ONE MAY BE NECESSARY FROM THE VAN HORN CORRIDOR TO THE PERMIAN BASIN TOMORROW. SNOW ACCUMULATIONS OF 3 TO 5 INCHES...WITH ISOLATED AMOUNTS OVER 6 INCHES LOOK PROBABLE ACROSS SOUTHEAST NEW MEXICO AND THE GUADALUPE MOUNTAINS BY TOMORROW EVENING IN THE WINTER STORM WARNING AREA. HIGH TEMPERATURES HAVE BEEN ADJUSTED DOWNWARD ACROSS A GOOD PORTION OF THE AREA. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT MST SATURDAY NIGHT FOR THE FOLLOWING ZONES...CENTRAL LEA COUNTY...EDDY COUNTY PLAINS...GUADALUPE MOUNTAINS OF EDDY COUNTY...NORTHERN LEA COUNTY...SOUTHERN LEA COUNTY. TX...WINTER STORM WATCH FROM 6 AM SATURDAY TO 12 PM CST SUNDAY FOR THE FOLLOWING ZONES...ANDREWS...BORDEN...CRANE... DAVIS/APACHE MOUNTAINS AREA...DAWSON...ECTOR...GAINES... GLASSCOCK...HOWARD...LOVING...MARTIN...MIDLAND...MITCHELL... PECOS...REAGAN...REEVES COUNTY AND UPPER TRANS PECOS... SCURRY...UPTON...VAN HORN AND HIGHWAY 54 CORRIDOR...WARD... WINKLER. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT MST SATURDAY NIGHT FOR THE FOLLOWING ZONES...GUADALUPE MOUNTAINS. && $$ 21 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 751 PM CST FRI NOV 23 2007 .UPDATE... ADDED BEAVER...OCHILTREE AND LIPSCOMB COUNTIES TO THE SNOW ADVISORY. CALLS UP TO BEAVER REVEAL THAT THERE IS 2 INCHES OF SNOW ON THE GROUND NOW. RADAR AND SATELLITE TRENDS SUGGEST THAT MORE SNOW IS HEADED TOWARD THIS AREA...THEREFORE THE SNOW ADVISORY. && .PREV DISCUSSION... /ISSUED 649 PM CST FRI NOV 23 2007/ UPDATE... WENT AHEAD AND EXTENDED THE SNOW ADVISORY UNTIL 6 AM SATURDAY FOR THE SAME AREA. SNOW ACROSS EASTERN NEW MEXICO IS EXPECTED TO CONTINUE SPREADING EAST ACROSS OUR AREA. LOW LEVEL UPSLOPE FLOW ALONG WITH THE ENTRANCE REGION OF THE JET STREAM MOVING OVER SHOULD ENHANCE SNOWFALL ACROSS THE ADVISORY AREA. 1 TO 3 INCH ADDITIONAL ACCUMULATIONS ARE EXPECTED WITH THE GREATEST AMOUNTS IN THE WESTERN OKLAHOMA AND NORTHWEST TEXAS PANHANDLE MAINLY NORTHWEST OF A LINE FROM GUYMON TO ADRIAN. PREV DISCUSSION... /ISSUED 616 PM CST FRI NOV 23 2007/ AVIATION... SNOW CONTINUES TO INCREASE IN COVERAGE ACROSS CENTRAL NEW MEXICO GENERATED BY A S/WV TROUGH NEAR THE FOUR CORNERS REGION. EXPECT THIS AREA OF SNOW TO BECOME MORE WIDESPREAD TONIGHT. THUS INSERTED PREVAILING LIGHT SNOW WITH MVFR CIGS AND VISBYS INITIALLY. APPEARS THE BEST FRONTOGENICAL LIFT WILL BE FOCUSED ACROSS THE NORTHERN TAF SITES WHERE CIGS CAN DETERIORATE TO IFR. DID ALSO MENTION IFR CIGS AT KAMA IN A TEMPO GROUP DUE TO A 90 KT JET STREAK THAT IS FORECAST TO MOVE ACROSS THE PANHANDLES. POINT FCST SOUNDINGS CONTINUE TO INDICATE A MOIST BOUNDARY LAYER AND COUPLED WITH LIGHT WINDS...AREAS OF FREEZING FOG ARE POSSIBLE. AFTER 12Z...EXPECT THE LIGHT SNOW TO GRADUALLY END AS THE S/WV PASSES TO THE EAST AND THE LIFT DIMINISHES. CONFIDENCE IN CONDITIONS IMPROVING RAPIDLY IS RATHER LOW...SO HELD ONTO MVFR CIGS FROM 13Z ON. CLK PREV DISCUSSION... /ISSUED 349 PM CST FRI NOV 23 2007/ DISCUSSION... SNOW ADVISORY WILL CONTINUE UNTIL 6 PM. RUC ANALYSIS SHOWS A FEW HOUR WINDOW WHERE ADDITIONAL SNOW FALL IS POSSIBLE IN THE ADVISORY AREA. WV IMAGERY STILL SHOWS A WEAK WAVE PUSHING THROUGH CENTRAL NEW MEXICO TOWARD THE PANHANDLES...WITH ABQ RADAR SHOWING A BAND OF SNOW MOVING EAST ALONG WITH THE SHORT WAVE. MODELS DIFFER ON WHEN TO END THE PRECIP OVER THE PANHANDLES...BUT THE GENERAL CONSENSUS IS FOR DRIER AIR TO PREVAIL AFTER 00Z. WOULD LIKE TO SEE HOW FAR EAST THE BAND OF SNOW OVER CENTRAL NEW MEXICO IS ABLE TO TRAVEL BEFORE BEING CONFIDENT IN EXTENDING THE SNOW ADVISORY. MODELS INDICATE THE ISENTROPIC LIFT WILL DIMINISH AFTER 00Z...WHILE THE COLD FRONT WILL BE NEARING THE OKLAHOMA PANHANDLE. FRONT MAY ACT AS A NEW SOURCE FOR LIFT...BUT AIRMASS IS DRIER BEHIND THE FRONT. SO WILL ALLOW THE CURRENT ADVISORY TO PLAY OUT UNTIL 00Z...AND WILL NOT EXTEND IN TIME FOR NOW. COULD STILL SEE LIGHT ACCUMULATIONS SO LEFT THE HIGH END CHANCE POPS IN PLACE THROUGH SATURDAY MORNING. OVERNIGHT LOWS WILL DEPEND ON CLOUD COVER AND SFC MOISTURE. APPEARS SKIES WILL REMAIN CLOUDY OVERNIGHT...WHILE DEW POINTS WILL GRADUALLY DECREASE WITH THE FRONTAL PASSAGE. FRONT SHOULD MOVE INTO NORTHWEST PANHANDLES BY 12Z...WITH DEW POINTS FALLING INTO THE UPPER TEENS. SO LIKEWISE KEPT THE LOWEST TEMPS ACROSS THE NW. INSERTED MENTION OF PATCHY FOG IN THE GRIDS THROUGH THE MORNING HOURS. SURFACE OBS HAVE PERIODICALLY REPORTED FOG AND THINKING THE AIRMASS WILL NEAR SATURATION AS OVERNIGHT TEMPS DECREASE. NOT CONFIDENT ON DENSE FOG HOWEVER. THE FRONT SHOULD THEN MOVE THROUGH THE PANHANDLES BY 18Z SATURDAY. DIFFICULT TO SAMPLE THE POST FRONTAL AIRMASS WITH THE SNOW AND CLOUD CONTAMINATION TAKING PLACE TO THE NORTH AND WEST...BUT THINKING CLOUD COVER WILL DECREASE SOME WHAT TOMORROW AND WIND SPEEDS SHOULD ONLY MAX OUT AT 10 TO 15KT. SO HIGH TEMPS SHOULD BE SIMILAR IF NOT A DEGREE OR TWO WARMER TOMORROW. THERE IS ALSO SOME POTENTIAL FOR SNOW TO LINGER ACROSS THE EXTREME SOUTHERN CWA INTO THE EARLY AFTERNOON HOURS TOMORROW. MODELS STILL A BIT UNSURE ON THE SOUTHERLY PROGRESSION OF THE MAIN UPPER LOW...BUT THE GFS AND NAM DO HINT AT LIGHT SNOW FOR A FEW HOURS AFTER 18Z. INSERTED A THIN ROW OF SLIGHT CHANCE POPS ALONG THE SOUTHER TEXAS PANHANDLE. AFTER THAT...THE MODELS DIVERGE SLIGHTLY ON THE TRACK OF THE LOW. WITH THE 12Z RUNS...THE NAM IS THE OUTLIER SHOWING THE FURTHEST NORTH AND WESTERN TRACK. IN ADDITION...THE NAM PAINTS SOME WRAP AROUND PRECIP INTO THE EASTERN PANHANDLES THROUGH SUNDAY. WHILE THE GFS/EURO/AND UKMET PULL THE LOW MORE TO THE SOUTH AND EAST. SO...DECIDED TO INSERT NON MENTIONABLE POPS ACROSS THE EAST BUT DID NOT BITE OFF ON THE NAM. A WARMING TREND COULD THEN BE IN THE WORKS FOR MONDAY AND TUESDAY...IF MID 50S ARE CONSIDERED WARM. NONETHELESS...WITH THE UPPER LOW PUSHING NORTHEAST...AND THE COLD FRONT WELL SOUTH OF THE PANHANDLES...SOUTHERLY SFC FLOW WILL ADVECT SLIGHTLY WARMER TEMPS INTO THE AREA FOR MONDAY. ESPECIALLY IF SKIES CLEAR OUT. UPPER FLOW BECOMES MORE SOUTHWESTERLY ON TUESDAY AND A LEE TROUGH DEVELOPED PROVIDING SOUTHWEST SFC FLOW. MEX WAS SUGGESTING HIGHS NEAR 60. FELT THAT MIGHT BE A TAD OPTIMISTIC SO WENT WITH MID 50S AREA WIDE. A STRONGER FRONT IS THEN PROGGED TO REACH THE SOUTHERN PLAINS WEDNESDAY AS A DEEPENING UPPER TROUGH DIGS SOUTH ALONG THE ROCKIES. MODELS SHOWING THE FRONT TO BE DRY...SO BIGGEST ISSUE WILL BE THE STRENGTH OF THE COLD AIR. APPEAR THE TROUGH WILL DRIVE SOUTH OUT OF THE GULF OF ALASKA. SO AT THIS POINT...DECIDED TO TREND WITH THE MEX AS IT HAD REASONABLE HIGH TEMPS FOR THE THURSDAY FRIDAY TIME FRAME. LAST MAJOR CHANGE WAS TO REMOVE THE POPS FROM THURSDAY. MODELS ARE COMING IN DRY WITH THE LATEST RUNS...AND SEEM TO BE PUSHING THE CHANCES FOR PRECIP BACK WITH EACH RUN. SO INSERTED SOME 10 POPS FOR THE DAY 7 AND 8 TIME FRAME...AND WILL WAIT TO SEE WHAT THE NEXT RUN HAS IN STORE. JJB && .AMA WATCHES/WARNINGS/ADVISORIES... TX...SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...DALLAM...DEAF SMITH...HANSFORD... HARTLEY...HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE... OLDHAM...POTTER...RANDALL...SHERMAN. OK...SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. && $$ 05/15 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 649 PM CST FRI NOV 23 2007 .UPDATE... WENT AHEAD AND EXTENDED THE SNOW ADVISORY UNTIL 6 AM SATURDAY FOR THE SAME AREA. SNOW ACROSS EASTERN NEW MEXICO IS EXPECTED TO CONTINUE SPREADING EAST ACROSS OUR AREA. LOW LEVEL UPSLOPE FLOW ALONG WITH THE ENTRANCE REGION OF THE JET STREAM MOVING OVER SHOULD ENHANCE SNOWFALL ACROSS THE ADVISORY AREA. 1 TO 3 INCH ADDITIONAL ACCUMULATIONS ARE EXPECTED WITH THE GREATEST AMOUNTS IN THE WESTERN OKLAHOMA AND NORTHWEST TEXAS PANHANDLE MAINLY NORTHWEST OF A LINE FROM GUYMON TO ADRIAN. && .PREV DISCUSSION... /ISSUED 616 PM CST FRI NOV 23 2007/ AVIATION... SNOW CONTINUES TO INCREASE IN COVERAGE ACROSS CENTRAL NEW MEXICO GENERATED BY A S/WV TROUGH NEAR THE FOUR CORNERS REGION. EXPECT THIS AREA OF SNOW TO BECOME MORE WIDESPREAD TONIGHT. THUS INSERTED PREVAILING LIGHT SNOW WITH MVFR CIGS AND VISBYS INITIALLY. APPEARS THE BEST FRONTOGENICAL LIFT WILL BE FOCUSED ACROSS THE NORTHERN TAF SITES WHERE CIGS CAN DETERIORATE TO IFR. DID ALSO MENTION IFR CIGS AT KAMA IN A TEMPO GROUP DUE TO A 90 KT JET STREAK THAT IS FORECAST TO MOVE ACROSS THE PANHANDLES. POINT FCST SOUNDINGS CONTINUE TO INDICATE A MOIST BOUNDARY LAYER AND COUPLED WITH LIGHT WINDS...AREAS OF FREEZING FOG ARE POSSIBLE. AFTER 12Z...EXPECT THE LIGHT SNOW TO GRADUALLY END AS THE S/WV PASSES TO THE EAST AND THE LIFT DIMINISHES. CONFIDENCE IN CONDITIONS IMPROVING RAPIDLY IS RATHER LOW...SO HELD ONTO MVFR CIGS FROM 13Z ON. CLK PREV DISCUSSION... /ISSUED 349 PM CST FRI NOV 23 2007/ DISCUSSION... SNOW ADVISORY WILL CONTINUE UNTIL 6 PM. RUC ANALYSIS SHOWS A FEW HOUR WINDOW WHERE ADDITIONAL SNOW FALL IS POSSIBLE IN THE ADVISORY AREA. WV IMAGERY STILL SHOWS A WEAK WAVE PUSHING THROUGH CENTRAL NEW MEXICO TOWARD THE PANHANDLES...WITH ABQ RADAR SHOWING A BAND OF SNOW MOVING EAST ALONG WITH THE SHORT WAVE. MODELS DIFFER ON WHEN TO END THE PRECIP OVER THE PANHANDLES...BUT THE GENERAL CONSENSUS IS FOR DRIER AIR TO PREVAIL AFTER 00Z. WOULD LIKE TO SEE HOW FAR EAST THE BAND OF SNOW OVER CENTRAL NEW MEXICO IS ABLE TO TRAVEL BEFORE BEING CONFIDENT IN EXTENDING THE SNOW ADVISORY. MODELS INDICATE THE ISENTROPIC LIFT WILL DIMINISH AFTER 00Z...WHILE THE COLD FRONT WILL BE NEARING THE OKLAHOMA PANHANDLE. FRONT MAY ACT AS A NEW SOURCE FOR LIFT...BUT AIRMASS IS DRIER BEHIND THE FRONT. SO WILL ALLOW THE CURRENT ADVISORY TO PLAY OUT UNTIL 00Z...AND WILL NOT EXTEND IN TIME FOR NOW. COULD STILL SEE LIGHT ACCUMULATIONS SO LEFT THE HIGH END CHANCE POPS IN PLACE THROUGH SATURDAY MORNING. OVERNIGHT LOWS WILL DEPEND ON CLOUD COVER AND SFC MOISTURE. APPEARS SKIES WILL REMAIN CLOUDY OVERNIGHT...WHILE DEW POINTS WILL GRADUALLY DECREASE WITH THE FRONTAL PASSAGE. FRONT SHOULD MOVE INTO NORTHWEST PANHANDLES BY 12Z...WITH DEW POINTS FALLING INTO THE UPPER TEENS. SO LIKEWISE KEPT THE LOWEST TEMPS ACROSS THE NW. INSERTED MENTION OF PATCHY FOG IN THE GRIDS THROUGH THE MORNING HOURS. SURFACE OBS HAVE PERIODICALLY REPORTED FOG AND THINKING THE AIRMASS WILL NEAR SATURATION AS OVERNIGHT TEMPS DECREASE. NOT CONFIDENT ON DENSE FOG HOWEVER. THE FRONT SHOULD THEN MOVE THROUGH THE PANHANDLES BY 18Z SATURDAY. DIFFICULT TO SAMPLE THE POST FRONTAL AIRMASS WITH THE SNOW AND CLOUD CONTAMINATION TAKING PLACE TO THE NORTH AND WEST...BUT THINKING CLOUD COVER WILL DECREASE SOME WHAT TOMORROW AND WIND SPEEDS SHOULD ONLY MAX OUT AT 10 TO 15KT. SO HIGH TEMPS SHOULD BE SIMILAR IF NOT A DEGREE OR TWO WARMER TOMORROW. THERE IS ALSO SOME POTENTIAL FOR SNOW TO LINGER ACROSS THE EXTREME SOUTHERN CWA INTO THE EARLY AFTERNOON HOURS TOMORROW. MODELS STILL A BIT UNSURE ON THE SOUTHERLY PROGRESSION OF THE MAIN UPPER LOW...BUT THE GFS AND NAM DO HINT AT LIGHT SNOW FOR A FEW HOURS AFTER 18Z. INSERTED A THIN ROW OF SLIGHT CHANCE POPS ALONG THE SOUTHER TEXAS PANHANDLE. AFTER THAT...THE MODELS DIVERGE SLIGHTLY ON THE TRACK OF THE LOW. WITH THE 12Z RUNS...THE NAM IS THE OUTLIER SHOWING THE FURTHEST NORTH AND WESTERN TRACK. IN ADDITION...THE NAM PAINTS SOME WRAP AROUND PRECIP INTO THE EASTERN PANHANDLES THROUGH SUNDAY. WHILE THE GFS/EURO/AND UKMET PULL THE LOW MORE TO THE SOUTH AND EAST. SO...DECIDED TO INSERT NON MENTIONABLE POPS ACROSS THE EAST BUT DID NOT BITE OFF ON THE NAM. A WARMING TREND COULD THEN BE IN THE WORKS FOR MONDAY AND TUESDAY...IF MID 50S ARE CONSIDERED WARM. NONETHELESS...WITH THE UPPER LOW PUSHING NORTHEAST...AND THE COLD FRONT WELL SOUTH OF THE PANHANDLES...SOUTHERLY SFC FLOW WILL ADVECT SLIGHTLY WARMER TEMPS INTO THE AREA FOR MONDAY. ESPECIALLY IF SKIES CLEAR OUT. UPPER FLOW BECOMES MORE SOUTHWESTERLY ON TUESDAY AND A LEE TROUGH DEVELOPED PROVIDING SOUTHWEST SFC FLOW. MEX WAS SUGGESTING HIGHS NEAR 60. FELT THAT MIGHT BE A TAD OPTIMISTIC SO WENT WITH MID 50S AREA WIDE. A STRONGER FRONT IS THEN PROGGED TO REACH THE SOUTHERN PLAINS WEDNESDAY AS A DEEPENING UPPER TROUGH DIGS SOUTH ALONG THE ROCKIES. MODELS SHOWING THE FRONT TO BE DRY...SO BIGGEST ISSUE WILL BE THE STRENGTH OF THE COLD AIR. APPEAR THE TROUGH WILL DRIVE SOUTH OUT OF THE GULF OF ALASKA. SO AT THIS POINT...DECIDED TO TREND WITH THE MEX AS IT HAD REASONABLE HIGH TEMPS FOR THE THURSDAY FRIDAY TIME FRAME. LAST MAJOR CHANGE WAS TO REMOVE THE POPS FROM THURSDAY. MODELS ARE COMING IN DRY WITH THE LATEST RUNS...AND SEEM TO BE PUSHING THE CHANCES FOR PRECIP BACK WITH EACH RUN. SO INSERTED SOME 10 POPS FOR THE DAY 7 AND 8 TIME FRAME...AND WILL WAIT TO SEE WHAT THE NEXT RUN HAS IN STORE. JJB && .AMA WATCHES/WARNINGS/ADVISORIES... TX...SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...DALLAM...DEAF SMITH...HANSFORD... HARTLEY...HUTCHINSON...MOORE...OLDHAM...POTTER...RANDALL... SHERMAN. OK...SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING ZONES: CIMARRON...TEXAS. && $$ 05/15 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 616 PM CST FRI NOV 23 2007 .AVIATION... SNOW CONTINUES TO INCREASE IN COVERAGE ACROSS CENTRAL NEW MEXICO GENERATED BY A S/WV TROUGH NEAR THE FOUR CORNERS REGION. EXPECT THIS AREA OF SNOW TO BECOME MORE WIDESPREAD TONIGHT. THUS INSERTED PREVAILING LIGHT SNOW WITH MVFR CIGS AND VISBYS INITIALLY. APPEARS THE BEST FRONTOGENICAL LIFT WILL BE FOCUSED ACROSS THE NORTHERN TAF SITES WHERE CIGS CAN DETERIORATE TO IFR. DID ALSO MENTION IFR CIGS AT KAMA IN A TEMPO GROUP DUE TO A 90 KT JET STREAK THAT IS FORECAST TO MOVE ACROSS THE PANHANDLES. POINT FCST SOUNDINGS CONTINUE TO INDICATE A MOIST BOUNDARY LAYER AND COUPLED WITH LIGHT WINDS...AREAS OF FREEZING FOG ARE POSSIBLE. AFTER 12Z...EXPECT THE LIGHT SNOW TO GRADUALLY END AS THE S/WV PASSES TO THE EAST AND THE LIFT DIMINISHES. CONFIDENCE IN CONDITIONS IMPROVING RAPIDLY IS RATHER LOW...SO HELD ONTO MVFR CIGS FROM 13Z ON. CLK && .PREV DISCUSSION... /ISSUED 349 PM CST FRI NOV 23 2007/ DISCUSSION... SNOW ADVISORY WILL CONTINUE UNTIL 6 PM. RUC ANALYSIS SHOWS A FEW HOUR WINDOW WHERE ADDITIONAL SNOW FALL IS POSSIBLE IN THE ADVISORY AREA. WV IMAGERY STILL SHOWS A WEAK WAVE PUSHING THROUGH CENTRAL NEW MEXICO TOWARD THE PANHANDLES...WITH ABQ RADAR SHOWING A BAND OF SNOW MOVING EAST ALONG WITH THE SHORT WAVE. MODELS DIFFER ON WHEN TO END THE PRECIP OVER THE PANHANDLES...BUT THE GENERAL CONSENSUS IS FOR DRIER AIR TO PREVAIL AFTER 00Z. WOULD LIKE TO SEE HOW FAR EAST THE BAND OF SNOW OVER CENTRAL NEW MEXICO IS ABLE TO TRAVEL BEFORE BEING CONFIDENT IN EXTENDING THE SNOW ADVISORY. MODELS INDICATE THE ISENTROPIC LIFT WILL DIMINISH AFTER 00Z...WHILE THE COLD FRONT WILL BE NEARING THE OKLAHOMA PANHANDLE. FRONT MAY ACT AS A NEW SOURCE FOR LIFT...BUT AIRMASS IS DRIER BEHIND THE FRONT. SO WILL ALLOW THE CURRENT ADVISORY TO PLAY OUT UNTIL 00Z...AND WILL NOT EXTEND IN TIME FOR NOW. COULD STILL SEE LIGHT ACCUMULATIONS SO LEFT THE HIGH END CHANCE POPS IN PLACE THROUGH SATURDAY MORNING. OVERNIGHT LOWS WILL DEPEND ON CLOUD COVER AND SFC MOISTURE. APPEARS SKIES WILL REMAIN CLOUDY OVERNIGHT...WHILE DEW POINTS WILL GRADUALLY DECREASE WITH THE FRONTAL PASSAGE. FRONT SHOULD MOVE INTO NORTHWEST PANHANDLES BY 12Z...WITH DEW POINTS FALLING INTO THE UPPER TEENS. SO LIKEWISE KEPT THE LOWEST TEMPS ACROSS THE NW. INSERTED MENTION OF PATCHY FOG IN THE GRIDS THROUGH THE MORNING HOURS. SURFACE OBS HAVE PERIODICALLY REPORTED FOG AND THINKING THE AIRMASS WILL NEAR SATURATION AS OVERNIGHT TEMPS DECREASE. NOT CONFIDENT ON DENSE FOG HOWEVER. THE FRONT SHOULD THEN MOVE THROUGH THE PANHANDLES BY 18Z SATURDAY. DIFFICULT TO SAMPLE THE POST FRONTAL AIRMASS WITH THE SNOW AND CLOUD CONTAMINATION TAKING PLACE TO THE NORTH AND WEST...BUT THINKING CLOUD COVER WILL DECREASE SOME WHAT TOMORROW AND WIND SPEEDS SHOULD ONLY MAX OUT AT 10 TO 15KT. SO HIGH TEMPS SHOULD BE SIMILAR IF NOT A DEGREE OR TWO WARMER TOMORROW. THERE IS ALSO SOME POTENTIAL FOR SNOW TO LINGER ACROSS THE EXTREME SOUTHERN CWA INTO THE EARLY AFTERNOON HOURS TOMORROW. MODELS STILL A BIT UNSURE ON THE SOUTHERLY PROGRESSION OF THE MAIN UPPER LOW...BUT THE GFS AND NAM DO HINT AT LIGHT SNOW FOR A FEW HOURS AFTER 18Z. INSERTED A THIN ROW OF SLIGHT CHANCE POPS ALONG THE SOUTHER TEXAS PANHANDLE. AFTER THAT...THE MODELS DIVERGE SLIGHTLY ON THE TRACK OF THE LOW. WITH THE 12Z RUNS...THE NAM IS THE OUTLIER SHOWING THE FURTHEST NORTH AND WESTERN TRACK. IN ADDITION...THE NAM PAINTS SOME WRAP AROUND PRECIP INTO THE EASTERN PANHANDLES THROUGH SUNDAY. WHILE THE GFS/EURO/AND UKMET PULL THE LOW MORE TO THE SOUTH AND EAST. SO...DECIDED TO INSERT NON MENTIONABLE POPS ACROSS THE EAST BUT DID NOT BITE OFF ON THE NAM. A WARMING TREND COULD THEN BE IN THE WORKS FOR MONDAY AND TUESDAY...IF MID 50S ARE CONSIDERED WARM. NONETHELESS...WITH THE UPPER LOW PUSHING NORTHEAST...AND THE COLD FRONT WELL SOUTH OF THE PANHANDLES...SOUTHERLY SFC FLOW WILL ADVECT SLIGHTLY WARMER TEMPS INTO THE AREA FOR MONDAY. ESPECIALLY IF SKIES CLEAR OUT. UPPER FLOW BECOMES MORE SOUTHWESTERLY ON TUESDAY AND A LEE TROUGH DEVELOPED PROVIDING SOUTHWEST SFC FLOW. MEX WAS SUGGESTING HIGHS NEAR 60. FELT THAT MIGHT BE A TAD OPTIMISTIC SO WENT WITH MID 50S AREA WIDE. A STRONGER FRONT IS THEN PROGGED TO REACH THE SOUTHERN PLAINS WEDNESDAY AS A DEEPENING UPPER TROUGH DIGS SOUTH ALONG THE ROCKIES. MODELS SHOWING THE FRONT TO BE DRY...SO BIGGEST ISSUE WILL BE THE STRENGTH OF THE COLD AIR. APPEAR THE TROUGH WILL DRIVE SOUTH OUT OF THE GULF OF ALASKA. SO AT THIS POINT...DECIDED TO TREND WITH THE MEX AS IT HAD REASONABLE HIGH TEMPS FOR THE THURSDAY FRIDAY TIME FRAME. LAST MAJOR CHANGE WAS TO REMOVE THE POPS FROM THURSDAY. MODELS ARE COMING IN DRY WITH THE LATEST RUNS...AND SEEM TO BE PUSHING THE CHANCES FOR PRECIP BACK WITH EACH RUN. SO INSERTED SOME 10 POPS FOR THE DAY 7 AND 8 TIME FRAME...AND WILL WAIT TO SEE WHAT THE NEXT RUN HAS IN STORE. JJB && .AMA WATCHES/WARNINGS/ADVISORIES... TX...SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...DALLAM...DEAF SMITH...HANSFORD... HARTLEY...HUTCHINSON...MOORE...OLDHAM...POTTER...RANDALL... SHERMAN. OK...SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING ZONES: CIMARRON...TEXAS. && $$ 05/15 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AMARILLO TX 349 PM CST FRI NOV 23 2007 .DISCUSSION... SNOW ADVISORY WILL CONTINUE UNTIL 6 PM. RUC ANALYSIS SHOWS A FEW HOUR WINDOW WHERE ADDITIONAL SNOW FALL IS POSSIBLE IN THE ADVISORY AREA. WV IMAGERY STILL SHOWS A WEAK WAVE PUSHING THROUGH CENTRAL NEW MEXICO TOWARD THE PANHANDLES...WITH ABQ RADAR SHOWING A BAND OF SNOW MOVING EAST ALONG WITH THE SHORT WAVE. MODELS DIFFER ON WHEN TO END THE PRECIP OVER THE PANHANDLES...BUT THE GENERAL CONSENSUS IS FOR DRIER AIR TO PREVAIL AFTER 00Z. WOULD LIKE TO SEE HOW FAR EAST THE BAND OF SNOW OVER CENTRAL NEW MEXICO IS ABLE TO TRAVEL BEFORE BEING CONFIDENT IN EXTENDING THE SNOW ADVISORY. MODELS INDICATE THE ISENTROPIC LIFT WILL DIMINISH AFTER 00Z...WHILE THE COLD FRONT WILL BE NEARING THE OKLAHOMA PANHANDLE. FRONT MAY ACT AS A NEW SOURCE FOR LIFT...BUT AIRMASS IS DRIER BEHIND THE FRONT. SO WILL ALLOW THE CURRENT ADVISORY TO PLAY OUT UNTIL 00Z...AND WILL NOT EXTEND IN TIME FOR NOW. COULD STILL SEE LIGHT ACCUMULATIONS SO LEFT THE HIGH END CHANCE POPS IN PLACE THROUGH SATURDAY MORNING. OVERNIGHT LOWS WILL DEPEND ON CLOUD COVER AND SFC MOISTURE. APPEARS SKIES WILL REMAIN CLOUDY OVERNIGHT...WHILE DEW POINTS WILL GRADUALLY DECREASE WITH THE FRONTAL PASSAGE. FRONT SHOULD MOVE INTO NORTHWEST PANHANDLES BY 12Z...WITH DEW POINTS FALLING INTO THE UPPER TEENS. SO LIKEWISE KEPT THE LOWEST TEMPS ACROSS THE NW. INSERTED MENTION OF PATCHY FOG IN THE GRIDS THROUGH THE MORNING HOURS. SURFACE OBS HAVE PERIODICALLY REPORTED FOG AND THINKING THE AIRMASS WILL NEAR SATURATION AS OVERNIGHT TEMPS DECREASE. NOT CONFIDENT ON DENSE FOG HOWEVER. THE FRONT SHOULD THEN MOVE THROUGH THE PANHANDLES BY 18Z SATURDAY. DIFFICULT TO SAMPLE THE POST FRONTAL AIRMASS WITH THE SNOW AND CLOUD CONTAMINATION TAKING PLACE TO THE NORTH AND WEST...BUT THINKING CLOUD COVER WILL DECREASE SOME WHAT TOMORROW AND WIND SPEEDS SHOULD ONLY MAX OUT AT 10 TO 15KT. SO HIGH TEMPS SHOULD BE SIMILAR IF NOT A DEGREE OR TWO WARMER TOMORROW. THERE IS ALSO SOME POTENTIAL FOR SNOW TO LINGER ACROSS THE EXTREME SOUTHERN CWA INTO THE EARLY AFTERNOON HOURS TOMORROW. MODELS STILL A BIT UNSURE ON THE SOUTHERLY PROGRESSION OF THE MAIN UPPER LOW...BUT THE GFS AND NAM DO HINT AT LIGHT SNOW FOR A FEW HOURS AFTER 18Z. INSERTED A THIN ROW OF SLIGHT CHANCE POPS ALONG THE SOUTHER TEXAS PANHANDLE. AFTER THAT...THE MODELS DIVERGE SLIGHTLY ON THE TRACK OF THE LOW. WITH THE 12Z RUNS...THE NAM IS THE OUTLIER SHOWING THE FURTHEST NORTH AND WESTERN TRACK. IN ADDITION...THE NAM PAINTS SOME WRAP AROUND PRECIP INTO THE EASTERN PANHANDLES THROUGH SUNDAY. WHILE THE GFS/EURO/AND UKMET PULL THE LOW MORE TO THE SOUTH AND EAST. SO...DECIDED TO INSERT NON MENTIONABLE POPS ACROSS THE EAST BUT DID NOT BITE OFF ON THE NAM. A WARMING TREND COULD THEN BE IN THE WORKS FOR MONDAY AND TUESDAY...IF MID 50S ARE CONSIDERED WARM. NONETHELESS...WITH THE UPPER LOW PUSHING NORTHEAST...AND THE COLD FRONT WELL SOUTH OF THE PANHANDLES...SOUTHERLY SFC FLOW WILL ADVECT SLIGHTLY WARMER TEMPS INTO THE AREA FOR MONDAY. ESPECIALLY IF SKIES CLEAR OUT. UPPER FLOW BECOMES MORE SOUTHWESTERLY ON TUESDAY AND A LEE TROUGH DEVELOPED PROVIDING SOUTHWEST SFC FLOW. MEX WAS SUGGESTING HIGHS NEAR 60. FELT THAT MIGHT BE A TAD OPTIMISTIC SO WENT WITH MID 50S AREA WIDE. A STRONGER FRONT IS THEN PROGGED TO REACH THE SOUTHERN PLAINS WEDNESDAY AS A DEEPENING UPPER TROUGH DIGS SOUTH ALONG THE ROCKIES. MODELS SHOWING THE FRONT TO BE DRY...SO BIGGEST ISSUE WILL BE THE STRENGTH OF THE COLD AIR. APPEAR THE TROUGH WILL DRIVE SOUTH OUT OF THE GULF OF ALASKA. SO AT THIS POINT...DECIDED TO TREND WITH THE MEX AS IT HAD REASONABLE HIGH TEMPS FOR THE THURSDAY FRIDAY TIME FRAME. LAST MAJOR CHANGE WAS TO REMOVE THE POPS FROM THURSDAY. MODELS ARE COMING IN DRY WITH THE LATEST RUNS...AND SEEM TO BE PUSHING THE CHANCES FOR PRECIP BACK WITH EACH RUN. SO INSERTED SOME 10 POPS FOR THE DAY 7 AND 8 TIME FRAME...AND WILL WAIT TO SEE WHAT THE NEXT RUN HAS IN STORE. JJB && .PRELIMINARY POINT TEMPS/POPS... AMARILLO TX 22 34 23 40 26 / 40 30 0 0 0 BEAVER OK 22 37 25 44 24 / 50 10 5 5 0 BOISE CITY OK 19 34 19 46 25 / 40 10 0 0 0 BORGER TX 25 37 25 44 29 / 40 20 0 0 0 BOYS RANCH TX 24 35 19 45 23 / 40 20 0 0 0 CANYON TX 23 35 21 43 25 / 50 30 0 0 0 CLARENDON TX 24 34 27 41 31 / 40 30 10 10 5 DALHART TX 21 35 18 44 22 / 40 10 0 0 0 GUYMON OK 21 34 19 48 23 / 50 10 0 0 0 HEREFORD TX 24 35 20 45 26 / 50 30 0 0 0 LIPSCOMB TX 24 38 25 43 23 / 50 10 10 10 10 PAMPA TX 23 34 26 41 30 / 40 20 5 5 5 SHAMROCK TX 25 36 27 43 27 / 40 20 10 10 10 WELLINGTON TX 26 36 28 42 28 / 40 20 10 10 10 && .AMA WATCHES/WARNINGS/ADVISORIES... TX...SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...DALLAM...DEAF SMITH... HANSFORD...HARTLEY...HUTCHINSON...MOORE...OLDHAM...POTTER... RANDALL...SHERMAN. OK...SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: CIMARRON...TEXAS. && $$ 01/14 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 1154 PM CST THU NOV 22 2007 .AVIATION... FOR THE 06Z TAFS...CURRENT WV IMAGERY SHOWS THE UPPER LOW HAS SLID SOUTH INTO WESTERN ARIZONA. LOW CLOUDS CONTINUE TO SPREAD EASTWARD AHEAD OF THE S/WV TROUGH THAT IS GENERATING -SN ACROSS PRTNS OF NEW MEXICO. LOOKS LIKE SNOW WILL CONTINUE TO SPREAD OVERNIGHT AND ENTER THE WESTERN PANHANDLES FRI MORNING. POINT FORECAST SOUNDINGS CONTINUE TO INDICATE THE COLUMN MOISTENING BY THE AFTERNOON SO INSERTED -SN AT ALL THREE TERMINALS. FOR NOW LOOKS LIKE VFR CONDITIONS AS MODELS SHOWING THE BEST LIFT WILL REMAIN SOUTH OF THE AREA. WINDS WILL REMAIN OUT OF THE SOUTHEAST WITH SPEEDS PICKING UP A BIT OVERNIGHT AND INCREASING TO AROUND 15 KTS BY FRI AFTERNOON. CLK && .PREV DISCUSSION... /ISSUED 804 PM CST THU NOV 22 2007/ UPDATE... HAVE UPDATED THE FORECAST LOW TEMPERATURES FOR TONIGHT. MID AND HIGH LEVEL CLOUDS ASSOCIATED WITH TODAYS DISTURBANCE HAVE EXITED THE FORECAST AREA AT THIS TIME. MORE CLOUDS WILL BEGIN MOVING IN FROM THE WEST SHORTLY AS OUR NEXT DISTURBANCE APPROACHES. DRY AIR AND THE BRIEF PERIOD OF CLEARING SKIES HAS ALLOWED TEMPERATURES TO DROP VERY QUICKLY ACROSS THE OKLAHOMA PANHANDLE WITH TEMPERATURES ALREADY IN THE LOW 20S IN SEVERAL SPOTS. HAVE LOWERED FORECAST LOWS FOR TONIGHT ACROSS THE OKLAHOMA PANHANDLE AND NORTHERN TEXAS PANHANDLE INTO THE MIDDLE TO UPPER TEENS. FEEL THE COLDEST LOCATIONS WILL BE IN THE NORTHEASTERN PANHANDLES AROUND BEAVER AND LIPSCOMB AS THIS WILL BE THE LAST AREA TO BEGIN CLOUDING OVER AGAIN TONIGHT. AREAS FURTHER WEST WILL NOT GET AS COLD AND MAY REACH THE FORECAST LOWS WITHIN THE NEXT FEW HOURS AND HOLD STEADY THE REMAINDER OF THE NIGHT AS CLOUDS AND POSSIBLE PRECIPITATION BEGIN TO MOVE IN. MADE MINOR CHANGES TO CLOUD COVER AS WELL. OTHERWISE NO CHANGES MADE TO CURRENT FORECAST. KIMBLE/GOEHRING PREV DISCUSSION... /ISSUED 624 PM CST THU NOV 22 2007/ AVIATION... MAIN WEATHER CONCERN FOR THIS FCST IS WITH CHANCES FOR LIGHT SNOW OVER THE PANHANDLES FRI. CURRENT WV IMAGERY CLEARLY SHOWS UPPER LOW OVER NEVADA WHILE RUC UPPER AIR ANALYSIS SHOWS A S/WV TROUGH MOVING SOUTH OF THE TEXAS PANHANDLE. CURRENT MOSAIC RADAR IMAGERY SHOWS AN AREA OF LIGHT SNOW OVER THE SOUTHERN TEXAS PANHANDLE. KEPT -SHSN OUT OF THE THREE TERMINALS TONIGHT AS THE LLVLS WILL REMAIN FAIRLY DRY. HOWEVER BY FRI MORNING...THE UPPER LOW WILL HEAD INTO THE FOUR CORNERS REGION. ANOTHER S/WV TROUGH IN ADVANCE OF THIS SYSTEM IS FORECAST TO TRACK INTO SOUTHWEST KANSAS FRI AFTERNOON. SFC WINDS WILL VEER AROUND TO THE SOUTHEAST...INCREASING THE MOISTURE RETURN IN THE LLVLS ALTHOUGH BUFKIT SOUNDINGS INDICATE THE COLUMN WILL MOISTEN UP SLOWLY. REGARDLESS FEEL ENOUGH MOISTURE WILL BE PRESENT AND GIVEN ISENTROPIC ASCENT...INSERTED PROB GROUPS FOR -SHSN AT ALL THREE TERMINALS BY THE AFTERNOON WITH MVFR CONDITIONS. CLK PREV DISCUSSION... /ISSUED 409 PM CST THU NOV 22 2007/ DISCUSSION... CURRENT RADAR TRENDS SEEM TO INDICATE THAT A WHITE THANKSGIVING WILL HAVE TO WAIT UNTIL NEXT YEAR. ALTHOUGH SAT IMAGERY SHOWS A WEAK WAVE THAT COULD REACH THE SOUTHWEST ZONES BEFORE MIDNIGHT SO LEFT THE SLIGHT CHANCE POPS IN FOR TONIGHT. DRY AIR AT THE SURFACE STILL LINGERING WITH DEW POINTS GENLY IN THE TEENS. SO EXPECT ANOTHER COLD NIGHT WITH TEMPS FALLING INTO THE UPPER TEENS TO LOW 20S. THE MAIN UPPER LOW IS CURRENTLY DIGGING SOUTH ALONG THE NEVADA AND CALIFORNIA BORDER. MODELS CONTINUE TO INDICATE THAT SOME OF THE ENERGY FROM THIS LOW WILL DISLODGE FROM THE MAIN TROUGH AND MOVE INTO THE PANHANDLES TOMORROW MORNING. A BIT CONCERNED WITH SFC MOISTURE VALUES AND WORRIED THAT MOISTURE RETURN MAY BE SLOWER THAN PREVIOUSLY THOUGHT. NONETHELESS...FORECAST SOUNDINGS SHOW MOISTURE ABOVE THE SURFACE THAT WILL MIX DOWN SOMETIME FRIDAY AFTERNOON. STILL APPEARS THE FRIDAY AFTERNOON INTO SATURDAY MORNING TIME FRAME WILL HOLD THE BEST SHOT FOR ACCUMULATING SNOW. HOWEVER...MODELS ARE STARTING TO DRAG THE UPPER LOW FURTHER SOUTH. SO THE PRECIP POTENTIAL WILL RELY HEAVILY ON THE SHORT WAVE THAT WILL MOVE THROUGH THE PANHANDLES FRIDAY. NAM IS STILL A BIT DRIER THAN THE GFS/EURO...BUT NOW PAINTS BORDERLINE ADVISORY SNOWFALL FRIDAY EVENING ACROSS THE WESTERN ZONES. MODEL SOLUTIONS ALSO INDICATE A SIMILAR ISENTROPIC LIFT REGIME ON FRIDAY. SO STILL FEEL THAT 40 TO 50 POPS ARE JUSTIFIED BUT HESITANT TO GO MUCH HIGHER. WILL ONCE AGAIN GO WITH AN SPS HIGHLIGHTING SNOW AMOUNTS IN THE 1 TO 3 INCH RANGE...AND HOLD OFF ON AN ADVISORY BASED ON THE LIMITED CONFIDENCE ON WHERE ADVISORY SNOWFALL WILL TAKE PLACE. THE NAM FAVORS THE EXTREME WESTERN CWA...WHILE THE GFS LEANS TOWARD THE WESTERN AND NORTHERN CWA...AND THE EURO PAINTS A BULLSEYE ACROSS THE SOUTHERN TEXAS PANHANDLE. OTHERWISE...TRENDED WITH A BLEND OF THE MAV GUIDANCE AND PREVIOUS GRIDS FOR THE TEMP GRIDS. AS MENTIONED ABOVE...GFS AND EURO ARE NOW TAKING THE LOW FURTHER SOUTH THAN PREVIOUS RUNS. THIS COULD MEAN A MORE ABRUPT END TO THE PRECIP THAN PREVIOUSLY THOUGHT. CURRENT GRIDS LINGER PRECIP INTO SATURDAY...WITH A DRY FORECAST SATURDAY AFTERNOON AND SUNDAY. WITH THE DEEPER AND SLOWER TRACK OF THE UPPER LOW...ANY UPPER RIDGING WILL BE BRIEF. IN FACT...GFS NOW INDICATES ANOTHER WEAK FRONT AND COOL AIR DUMP INTO THE PANHANDLES MONDAY. COOLED OFF HIGH TEMPS ON MONDAY A FEW DEGREES AND CONTINUED THE COOLER TREND THROUGH THE REST OF THE WEEK. GFS AND EURO BOTH SHOW ANOTHER UPPER LOW DEVELOPING FOR THE DAY 6 AND 7 TIME FRAME. MODELS TAKE THE LOW ACROSS NEW MEXICO AND STILL PAINT PRECIP OVER THE PANHANDLES ON THURSDAY. SO BIGGEST CHANGE TO THE PACKAGE WAS TO INTRODUCE SLIGHT CHANCE POPS FOR LATE NEXT WEEK. HAPPY THANKSGIVING. JJB && AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 15/05 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 804 PM CST THU NOV 22 2007 .UPDATE... HAVE UPDATED THE FORECAST LOW TEMPERATURES FOR TONIGHT. MID AND HIGH LEVEL CLOUDS ASSOCIATED WITH TODAYS DISTURBANCE HAVE EXITED THE FORECAST AREA AT THIS TIME. MORE CLOUDS WILL BEGIN MOVING IN FROM THE WEST SHORTLY AS OUR NEXT DISTURBANCE APPROACHES. DRY AIR AND THE BRIEF PERIOD OF CLEARING SKIES HAS ALLOWED TEMPERATURES TO DROP VERY QUICKLY ACROSS THE OKLAHOMA PANHANDLE WITH TEMPERATURES ALREADY IN THE LOW 20S IN SEVERAL SPOTS. HAVE LOWERED FORECAST LOWS FOR TONIGHT ACROSS THE OKLAHOMA PANHANDLE AND NORTHERN TEXAS PANHANDLE INTO THE MIDDLE TO UPPER TEENS. FEEL THE COLDEST LOCATIONS WILL BE IN THE NORTHEASTERN PANHANDLES AROUND BEAVER AND LIPSCOMB AS THIS WILL BE THE LAST AREA TO BEGIN CLOUDING OVER AGAIN TONIGHT. AREAS FURTHER WEST WILL NOT GET AS COLD AND MAY REACH THE FORECAST LOWS WITHIN THE NEXT FEW HOURS AND HOLD STEADY THE REMAINDER OF THE NIGHT AS CLOUDS AND POSSIBLE PRECIPITATION BEGIN TO MOVE IN. MADE MINOR CHANGES TO CLOUD COVER AS WELL. OTHERWISE NO CHANGES MADE TO CURRENT FORECAST. KIMBLE/GOEHRING && .PREV DISCUSSION... /ISSUED 624 PM CST THU NOV 22 2007/ AVIATION... MAIN WEATHER CONCERN FOR THIS FCST IS WITH CHANCES FOR LIGHT SNOW OVER THE PANHANDLES FRI. CURRENT WV IMAGERY CLEARLY SHOWS UPPER LOW OVER NEVADA WHILE RUC UPPER AIR ANALYSIS SHOWS A S/WV TROUGH MOVING SOUTH OF THE TEXAS PANHANDLE. CURRENT MOSAIC RADAR IMAGERY SHOWS AN AREA OF LIGHT SNOW OVER THE SOUTHERN TEXAS PANHANDLE. KEPT -SHSN OUT OF THE THREE TERMINALS TONIGHT AS THE LLVLS WILL REMAIN FAIRLY DRY. HOWEVER BY FRI MORNING...THE UPPER LOW WILL HEAD INTO THE FOUR CORNERS REGION. ANOTHER S/WV TROUGH IN ADVANCE OF THIS SYSTEM IS FORECAST TO TRACK INTO SOUTHWEST KANSAS FRI AFTERNOON. SFC WINDS WILL VEER AROUND TO THE SOUTHEAST...INCREASING THE MOISTURE RETURN IN THE LLVLS ALTHOUGH BUFKIT SOUNDINGS INDICATE THE COLUMN WILL MOISTEN UP SLOWLY. REGARDLESS FEEL ENOUGH MOISTURE WILL BE PRESENT AND GIVEN ISENTROPIC ASCENT...INSERTED PROB GROUPS FOR -SHSN AT ALL THREE TERMINALS BY THE AFTERNOON WITH MVFR CONDITIONS. CLK PREV DISCUSSION... /ISSUED 409 PM CST THU NOV 22 2007/ DISCUSSION... CURRENT RADAR TRENDS SEEM TO INDICATE THAT A WHITE THANKSGIVING WILL HAVE TO WAIT UNTIL NEXT YEAR. ALTHOUGH SAT IMAGERY SHOWS A WEAK WAVE THAT COULD REACH THE SOUTHWEST ZONES BEFORE MIDNIGHT SO LEFT THE SLIGHT CHANCE POPS IN FOR TONIGHT. DRY AIR AT THE SURFACE STILL LINGERING WITH DEW POINTS GENLY IN THE TEENS. SO EXPECT ANOTHER COLD NIGHT WITH TEMPS FALLING INTO THE UPPER TEENS TO LOW 20S. THE MAIN UPPER LOW IS CURRENTLY DIGGING SOUTH ALONG THE NEVADA AND CALIFORNIA BORDER. MODELS CONTINUE TO INDICATE THAT SOME OF THE ENERGY FROM THIS LOW WILL DISLODGE FROM THE MAIN TROUGH AND MOVE INTO THE PANHANDLES TOMORROW MORNING. A BIT CONCERNED WITH SFC MOISTURE VALUES AND WORRIED THAT MOISTURE RETURN MAY BE SLOWER THAN PREVIOUSLY THOUGHT. NONETHELESS...FORECAST SOUNDINGS SHOW MOISTURE ABOVE THE SURFACE THAT WILL MIX DOWN SOMETIME FRIDAY AFTERNOON. STILL APPEARS THE FRIDAY AFTERNOON INTO SATURDAY MORNING TIME FRAME WILL HOLD THE BEST SHOT FOR ACCUMULATING SNOW. HOWEVER...MODELS ARE STARTING TO DRAG THE UPPER LOW FURTHER SOUTH. SO THE PRECIP POTENTIAL WILL RELY HEAVILY ON THE SHORT WAVE THAT WILL MOVE THROUGH THE PANHANDLES FRIDAY. NAM IS STILL A BIT DRIER THAN THE GFS/EURO...BUT NOW PAINTS BORDERLINE ADVISORY SNOWFALL FRIDAY EVENING ACROSS THE WESTERN ZONES. MODEL SOLUTIONS ALSO INDICATE A SIMILAR ISENTROPIC LIFT REGIME ON FRIDAY. SO STILL FEEL THAT 40 TO 50 POPS ARE JUSTIFIED BUT HESITANT TO GO MUCH HIGHER. WILL ONCE AGAIN GO WITH AN SPS HIGHLIGHTING SNOW AMOUNTS IN THE 1 TO 3 INCH RANGE...AND HOLD OFF ON AN ADVISORY BASED ON THE LIMITED CONFIDENCE ON WHERE ADVISORY SNOWFALL WILL TAKE PLACE. THE NAM FAVORS THE EXTREME WESTERN CWA...WHILE THE GFS LEANS TOWARD THE WESTERN AND NORTHERN CWA...AND THE EURO PAINTS A BULLSEYE ACROSS THE SOUTHERN TEXAS PANHANDLE. OTHERWISE...TRENDED WITH A BLEND OF THE MAV GUIDANCE AND PREVIOUS GRIDS FOR THE TEMP GRIDS. AS MENTIONED ABOVE...GFS AND EURO ARE NOW TAKING THE LOW FURTHER SOUTH THAN PREVIOUS RUNS. THIS COULD MEAN A MORE ABRUPT END TO THE PRECIP THAN PREVIOUSLY THOUGHT. CURRENT GRIDS LINGER PRECIP INTO SATURDAY...WITH A DRY FORECAST SATURDAY AFTERNOON AND SUNDAY. WITH THE DEEPER AND SLOWER TRACK OF THE UPPER LOW...ANY UPPER RIDGING WILL BE BRIEF. IN FACT...GFS NOW INDICATES ANOTHER WEAK FRONT AND COOL AIR DUMP INTO THE PANHANDLES MONDAY. COOLED OFF HIGH TEMPS ON MONDAY A FEW DEGREES AND CONTINUED THE COOLER TREND THROUGH THE REST OF THE WEEK. GFS AND EURO BOTH SHOW ANOTHER UPPER LOW DEVELOPING FOR THE DAY 6 AND 7 TIME FRAME. MODELS TAKE THE LOW ACROSS NEW MEXICO AND STILL PAINT PRECIP OVER THE PANHANDLES ON THURSDAY. SO BIGGEST CHANGE TO THE PACKAGE WAS TO INTRODUCE SLIGHT CHANCE POPS FOR LATE NEXT WEEK. HAPPY THANKSGIVING. JJB AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. $$ && $$ 13/15 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 624 PM CST THU NOV 22 2007 .AVIATION... MAIN WEATHER CONCERN FOR THIS FCST IS WITH CHANCES FOR LIGHT SNOW OVER THE PANHANDLES FRI. CURRENT WV IMAGERY CLEARLY SHOWS UPPER LOW OVER NEVADA WHILE RUC UPPER AIR ANALYSIS SHOWS A S/WV TROUGH MOVING SOUTH OF THE TEXAS PANHANDLE. CURRENT MOSAIC RADAR IMAGERY SHOWS AN AREA OF LIGHT SNOW OVER THE SOUTHERN TEXAS PANHANDLE. KEPT -SHSN OUT OF THE THREE TERMINALS TONIGHT AS THE LLVLS WILL REMAIN FAIRLY DRY. HOWEVER BY FRI MORNING...THE UPPER LOW WILL HEAD INTO THE FOUR CORNERS REGION. ANOTHER S/WV TROUGH IN ADVANCE OF THIS SYSTEM IS FORECAST TO TRACK INTO SOUTHWEST KANSAS FRI AFTERNOON. SFC WINDS WILL VEER AROUND TO THE SOUTHEAST...INCREASING THE MOISTURE RETURN IN THE LLVLS ALTHOUGH BUFKIT SOUNDINGS INDICATE THE COLUMN WILL MOISTEN UP SLOWLY. REGARDLESS FEEL ENOUGH MOISTURE WILL BE PRESENT AND GIVEN ISENTROPIC ASCENT...INSERTED PROB GROUPS FOR -SHSN AT ALL THREE TERMINALS BY THE AFTERNOON WITH MVFR CONDITIONS. CLK && .PREV DISCUSSION... /ISSUED 409 PM CST THU NOV 22 2007/ DISCUSSION... CURRENT RADAR TRENDS SEEM TO INDICATE THAT A WHITE THANKSGIVING WILL HAVE TO WAIT UNTIL NEXT YEAR. ALTHOUGH SAT IMAGERY SHOWS A WEAK WAVE THAT COULD REACH THE SOUTHWEST ZONES BEFORE MIDNIGHT SO LEFT THE SLIGHT CHANCE POPS IN FOR TONIGHT. DRY AIR AT THE SURFACE STILL LINGERING WITH DEW POINTS GENLY IN THE TEENS. SO EXPECT ANOTHER COLD NIGHT WITH TEMPS FALLING INTO THE UPPER TEENS TO LOW 20S. THE MAIN UPPER LOW IS CURRENTLY DIGGING SOUTH ALONG THE NEVADA AND CALIFORNIA BORDER. MODELS CONTINUE TO INDICATE THAT SOME OF THE ENERGY FROM THIS LOW WILL DISLODGE FROM THE MAIN TROUGH AND MOVE INTO THE PANHANDLES TOMORROW MORNING. A BIT CONCERNED WITH SFC MOISTURE VALUES AND WORRIED THAT MOISTURE RETURN MAY BE SLOWER THAN PREVIOUSLY THOUGHT. NONETHELESS...FORECAST SOUNDINGS SHOW MOISTURE ABOVE THE SURFACE THAT WILL MIX DOWN SOMETIME FRIDAY AFTERNOON. STILL APPEARS THE FRIDAY AFTERNOON INTO SATURDAY MORNING TIME FRAME WILL HOLD THE BEST SHOT FOR ACCUMULATING SNOW. HOWEVER...MODELS ARE STARTING TO DRAG THE UPPER LOW FURTHER SOUTH. SO THE PRECIP POTENTIAL WILL RELY HEAVILY ON THE SHORT WAVE THAT WILL MOVE THROUGH THE PANHANDLES FRIDAY. NAM IS STILL A BIT DRIER THAN THE GFS/EURO...BUT NOW PAINTS BORDERLINE ADVISORY SNOWFALL FRIDAY EVENING ACROSS THE WESTERN ZONES. MODEL SOLUTIONS ALSO INDICATE A SIMILAR ISENTROPIC LIFT REGIME ON FRIDAY. SO STILL FEEL THAT 40 TO 50 POPS ARE JUSTIFIED BUT HESITANT TO GO MUCH HIGHER. WILL ONCE AGAIN GO WITH AN SPS HIGHLIGHTING SNOW AMOUNTS IN THE 1 TO 3 INCH RANGE...AND HOLD OFF ON AN ADVISORY BASED ON THE LIMITED CONFIDENCE ON WHERE ADVISORY SNOWFALL WILL TAKE PLACE. THE NAM FAVORS THE EXTREME WESTERN CWA...WHILE THE GFS LEANS TOWARD THE WESTERN AND NORTHERN CWA...AND THE EURO PAINTS A BULLSEYE ACROSS THE SOUTHERN TEXAS PANHANDLE. OTHERWISE...TRENDED WITH A BLEND OF THE MAV GUIDANCE AND PREVIOUS GRIDS FOR THE TEMP GRIDS. AS MENTIONED ABOVE...GFS AND EURO ARE NOW TAKING THE LOW FURTHER SOUTH THAN PREVIOUS RUNS. THIS COULD MEAN A MORE ABRUPT END TO THE PRECIP THAN PREVIOUSLY THOUGHT. CURRENT GRIDS LINGER PRECIP INTO SATURDAY...WITH A DRY FORECAST SATURDAY AFTERNOON AND SUNDAY. WITH THE DEEPER AND SLOWER TRACK OF THE UPPER LOW...ANY UPPER RIDGING WILL BE BRIEF. IN FACT...GFS NOW INDICATES ANOTHER WEAK FRONT AND COOL AIR DUMP INTO THE PANHANDLES MONDAY. COOLED OFF HIGH TEMPS ON MONDAY A FEW DEGREES AND CONTINUED THE COOLER TREND THROUGH THE REST OF THE WEEK. GFS AND EURO BOTH SHOW ANOTHER UPPER LOW DEVELOPING FOR THE DAY 6 AND 7 TIME FRAME. MODELS TAKE THE LOW ACROSS NEW MEXICO AND STILL PAINT PRECIP OVER THE PANHANDLES ON THURSDAY. SO BIGGEST CHANGE TO THE PACKAGE WAS TO INTRODUCE SLIGHT CHANCE POPS FOR LATE NEXT WEEK. HAPPY THANKSGIVING. JJB && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 05/15 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 323 AM CST FRI NOV 23 2007 .SHORT TERM...TODAY THROUGH SATURDAY NIGHT PRECIPITATION CHANCES THIS MORNING AND FROM LATE TONIGHT THROUGH SATURDAY MORNING...AND TEMPERATURES TONIGHT ARE THE MAIN FORECAST CONCERNS. AT 3 AM...A 1036 MB SURFACE HIGH WAS CENTERED ACROSS EASTERN KANSAS. DOPPLER RADAR AND SURFACE OBSERVATIONS CONTINUE TO SHOW SOME FLURRIES FROM CENTRAL THROUGH SOUTHWEST WISCONSIN. THESE SNOW SHOWERS WERE ASSOCIATED WITH SOME LIFT ASSOCIATED WITH THE 500 MB SHORT WAVE TROUGH MOVING AWAY FROM THE REGION. ADDITIONAL FLURRIES WERE BEING REPORTED AND INDICATED ON THE KMPX RADAR BETWEEN LITCHFIELD AND MORA. IT APPEARS THAT THIS PRECIPITATION IS ASSOCIATED WITH WEAK 900 TO 800 MB FRONTOGENESIS. THE RUC INDICATES THAT THIS FORCING WILL CONTINUE TO GRADUALLY WEAKEN AND MOVE GENERALLY NORTH OF INTERSTATES 90 AND 94 THIS MORNING. DUE TO THIS...I HAVE ADDED A MENTION OF SCATTERED TO OCCASIONAL FLURRIES ACROSS WABASHA COUNTY IN SOUTHEAST MINNESOTA...BUFFALO AND TREMPEALEAU COUNTIES IN WEST CENTRAL WISCONSIN...JACKSON COUNTY IN CENTRAL WISCONSIN...AND CLARK AND TAYLOR COUNTIES IN NORTH CENTRAL WISCONSIN. THE MODELS CONTINUE TO BE IN FAIRLY GOOD AGREEMENT THAT THE AREA WILL SEE WEAK TO MODERATE WARM AIR ADVECTION AHEAD OF A 500 MB SHORT WAVE TROUGH THAT WILL BE MOVING THROUGH THE REGION ON SATURDAY MORNING. THE GFS CONTINUE TO GENERATE SOME LIGHT PRECIPITATION ACROSS PARTS OF NORTHERN WISCONSIN BETWEEN MIDNIGHT TONIGHT AND NOON SATURDAY. AS A RESULT...I KEPT THE 20 PERCENT CHANCE OF SNOW GOING ACROSS NORTH CENTRAL WISCONSIN. ELSEWHERE THERE MAY BE ENOUGH LIFT TO PRODUCE SOME SCATTERED FLURRIES. IN ADDITION TO THE PRECIPITATION...WE WILL LIKELY SEE TEMPERATURES COOL THROUGH THIS EVENING...AND THEN SLOWLY RISE OVERNIGHT. AS A RESULT...I DID NOT GO WITH THE NORMAL DIURNAL TEMPERATURE CURVE OVERNIGHT TONIGHT OR ON SATURDAY MORNING. .LONG TERM...SUNDAY THROUGH THURSDAY THE MODELS CONTINUE TO STRUGGLE WITH THE TRACK OF THE SURFACE LOW MOVING NORTHEAST OUT OF THE WESTERN GULF ON SUNDAY NIGHT. THE ECMWF AND GEM CONTINUE TO SHOW THAT THIS SYSTEM WILL MOVE FROM SOUTHWEST LOUISIANA ON SUNDAY EVENING TO WESTERN PENNSYLVANIA ON MONDAY EVENING. MEANWHILE THE GFS AND NAM SUGGEST THAT THIS LOW WILL MOVE FROM SOUTHWEST LOUISIANA TO THE WESTERN GREAT LAKES. DUE TO THE CONTINUED WIDE MODEL SPREAD...I LEFT THE CURRENT THE FORECAST FOR A SLIGHT CHANCE OF RAIN ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN ON MONDAY ALONE. THE NEXT SYSTEM OF INTEREST IS A YET ANOTHER LOW PRESSURE SYSTEM MOVING THROUGH THE THE REGION ON EITHER WEDNESDAY OR THURSDAY. THE GFS SUGGEST THE POTENTIAL OF A SNOW STORM ACROSS SOUTHEAST MINNESOTA AND NORTH CENTRAL WISCONSIN. HOWEVER IT IS NOW MOVING THROUGH THE REGION 24 HOURS FASTER THAN ITS NOVEMBER 22ND 12Z MODEL RUN. MEANWHILE...THE ECMWF SHOWS SIMILAR TIMING...BUT THE TRACK IS MUCH FURTHER NORTH AND THE ENTIRE AREA WILL SEE RAIN. WITH SUCH UNCERTAINTY AND VERY POOR TELECONNECTION VERIFICATION LATELY IN THIS TIME FRAME...I HAVE OPTED NOT TO MAKE ANY CHANGES TO THE EXISTING FORECAST. && .AVIATION...TODAY AND TONIGHT CONCERN FOR THE NEXT 24-30 HOURS IS ON CLOUD COVER. VFR STRATO-CU AND SOME FLURRIES OVER WI SHIFTING SLOWLY EAST OVERNIGHT...LOOKS TO NO LONGER BE A CONCERN TO THE TAF LOCATIONS...BUT COULD IMPACT LIGHTS EAST TOWARD KMSN-KMKE-KGRB. COLD TEMPERATURES LIKELY PROVIDING SOME FROST ON AIRCRAFT SURFACES WHICH WERE PARKED OVERNIGHT. ANOTHER CLOUD DECK AND SCATTERED FLURRIES ASSOCIATED WITH WEAK WARM ADVECTION SEEN ACROSS MN. MODELS SUPPORT THIS MOVING ACROSS NORTHERN PORTIONS OF OUR FORECAST AREA TODAY. DOES NOT APPEAR TO IMPACT TAF LOCATIONS EITHER...BUT MAY IMPACT FLIGHTS NORTH TOWARD KMSP-KDLH. OTHER THAN THIS...THERE MAY BE SOME HIGH CIRRUS...BUT OTHERWISE QUIET. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT AND LONG TERM - BOYNE AVIATION - MW wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 430 AM EST SAT NOV 24 2007 .DISCUSSION... CURRENT... COLD FRONT HAS PUSHED INTO THE FAR SRN PENINSULA AS OF 08Z. 3.9UM SHOWS PLENTY OF MARINE SC UPSTREAM OVER THE ATLC...ALTHOUGH KMLB INDICATES NIL PRECIP EMBEDDED WITHIN THESE CLOUDS. ALSO...RUC ANLYS AND IR IMAGERY SHOW INCRSG H25 DIVG OVER THE ERN GOMEX FL ACSD WITH BROAD JET STREAK UPSTREAM. THIS IS RESULTING IN AN INCRS IN CI/CS OVHD. INTERESTING TEMP DISTRIBUTION ALONG THE EAST COAST BTWN SITES WHERE BLYR HAS DECOUPLED (MLB/56F FPR-TIX/57F) VS. SITES WHERE FLOW IS STILL NNE AROUND 10KT (DAB/65F VRB/69F X59/72F). SUSPECT THIS IS DEPENDENT ON DISTANCE BTWN AIRPORT CTRFIELD AND THE COAST...OR PERHAPS THE INTRACOASTAL WATERWAY. TODAY/TONIGHT... SYNOPTIC PATTERN SHOWS MID/UPR HGHTS RISING SOME AS NERN CONUS SHORT WAVE TROUGH ZIPS EWD INTO THE NWRN ATLC WHILST SWRN CONUS CUTOFF LOW DIGS SEWD INTO OLD MEX. LARGE COLD ERN CONUS SFC HIGH PUSHES RAPIDLY OFFSHORE IN ZONAL WSW-ESE MID/UPPER FLOW...WHICH ALLOW SFC FLOW TO VEER QUICKLY AROUND TO EAST TODAY AND ESE/SE BY TONIGHT. WHILE MODELS INCREASE MEAN PWAT SOME OVER THE NEXT H24...OTHER THAN A FEW COASTAL SPRINKLES FALLING OUT OF THE SHOREWARD MOVG MARINE SC DECK...THERE IS NIL LOW-MID LEVEL FORCED ASCENT...AND THE MEAGER H25 JET DIVG WILL DO LITTLE ELSE THAN KEEP HIGH CLOUDS OVHD. HAVE REMOVED PRECIP CHCS TODAY/TONIGHT...AND BUMPED UP CLOUD A BIT FOR TODAY. SUN/SUN NIGHT... PUSHED BY A STRONG DLM WRLY FLOW...THE SFC-H70 RIDGE AXIS OVER THE MIDWEST WILL PUSH WELL OFF THE ERN SEABOARD BY DAYBREAK SUN. MEANWHILE...A SHORTWAVE TROF OVER THE DESERT SW WILL KICK AN H85-H50 RIDGE OVER THE FL PENINSULA INTO THE WRN ATLC. THESE TWO RIDGING FEATURES WILL MERGE INTO A POTENT DLM ANTICYCLONE OVER THE WRN N ATLC...WHICH WILL GENERATE A STRONG S/SERLY RETURN FLOW ACROSS THE STATE. THE FLOW WILL PUSH THE STALLED FRONTAL BOUNDARY OVER S FL BACK TO THE N AS A WEAK WARM FRONT. STRONG ISENTROPIC LIFT WILL DEVELOP ACROSS THE FL PENINSULA AS THE LOW/MID LVL WINDS VEER TO THE S/SE...SUGGESTING SOME FORM OF STRATIFORM PRECIP EVENT ON SUN. HOWEVER...DLM MOISTURE WITHIN THE VICINITY OF THE FRONT IS RATHER LIMITED: PW OFF THE 00Z KMFL SOUNDING WERE 1.5"...MOST OF WHICH IS SANDWICHED WITHIN THE H90-H70 LYR. BEHIND THE FRONT...PW VALUES DROP TO 0.7"-0.8". WILL KEEP SMALL POPS IN THE FCST FOR THE CENTRAL/SRN CWA AS THE FRONT MOVES BACK TO THE N...BUT WITH A LIMITED MOISTURE FIELD BUILDING INTO SUCH A LOW MOISTURE FIELD...PRECIP AMOUNTS WILL HAVE A LOW IMPACT...GENERALLY AOB 0.10". STEADY S/SERLY FLOW WILL KEEP TEMPS ~10F DEG ABV CLIMO. MON-TUE... THE AFOREMENTIONED SHORT WAVE TROF WILL SPIN UP A BROAD SFC LOW OVER NRN MEX INTO A WELL DEVELOPED STORM SYSTEM OVER THE TN RIVER VALLEY BY DAYBREAK MON. HOWEVER...IN DOING SO THE TROF WILL SHIFT FROM A DIGGING TO A LIFTING ORIENTATION...JUST AS IT BEGINS TO ENCOUNTER THE RIDGE OVER THE WRN ATLC. GFS/ECMWF MODELS ARE NOW LEANING TO A COLD FROPA THROUGH THE CENTRAL PENINSULA BY LATE TUE NIGHT...BUT WITH THE PARENT STORM SYSTEM LIFTING AWAY...IT WILL ABANDON SRN EXTENSION OF THE FRONT. THIS PATTERN WOULD BE VERY SIMILAR TO THE FROPA THAT JUST TRANSPIRED...AND GIVEN THE CURRENT LA NINA WX PATTERN...IT SEEMS ENTIRELY PLAUSIBLE. WILL CAP POPS AT 20% WITH NO MENTION OF THUNDER. CONTINUED SRLY FLOW WILL KEEP MAX-MIN TEMPS ~10F DEG ABV CLIMO THRU TUE MORNING. WEAK COOL AIR ADVECTION BEHIND THE FROPA MAY BE ABLE TO RETURN MAX TEMPS TO WITHIN ~5F DEG OF CLIMO TUE/TUE NIGHT...BUT NO MAJOR COOL DOWN. WED-FRI... MID RANGE MODELS CONTINUE TO INDICATE STRONG H85-H50 RIDGING OVER THE GOMEX/SW ATLC REGION THRU THE UPCOMING WEEK. THIS WOULD LIMIT MOISTURE RETURN AND VERTICAL MOTION...AS WELL A POSING A FORMIDABLE BARRIER FOR THE NEXT FRONTAL SYSTEM TO PUSH INTO THE STATE. EVEN IF ONE WERE TO OCCUR...IT TOO...WOULD LOSE MOST OF ITS STRENGTH AS IT "RUNS THE GAUNTLET". INDEED...GFS EXTENDED MOS GUIDANCE INDICATES A LATE WEEK COOL DOWN OF 5-10F DEG WITH NEGLIGIBLE POPS. AT THE RISK OF SOUNDING LIKE A BROKEN RECORD...IT`S HARD TO ARGUE THIS SOLUTION IN A LA NINA YEAR. && .AVIATION... THINK COMBINATION OF ONSHORE FLOW OF UPSTREAM MARINE SC AND DIURNAL HEATING WILL CAUSE PREVAILING VFR BKN SC CIGS AT MOST SITES FROM LATE MORNING/EARLY AFTN ONWARD TODAY...ESPEC NR THE COAST. CAVEAT HERE IS THAT BKN HIGH LVL CIGS COULD INHIBITING INSOLATION ENOUGH TO KEEP LOWER CLDS SCT. MAV MOS IS PRETTY GUNG-HO ON MVFR TO LCL IFR CONDS IN MIST/FOG LATE TONIGHT. MAY NEED TO THROW IN SOME MVFR VSBYS INTO THE NORMALLY PRONE TAF SITES FOR THE 12Z PACKAGE...THOUGH NOT SURE HIGH CLOUDS WILL THIN ENOUGH FOR CONDS TO DROP BELOW MVFR. && .MARINE... IT`S CLEAR NOW THAT WNAWAVE GUIDANCE HAS OVERDONE EXTENT OF THIS EVENT. NRN MARINE ZONES WERE FCST TO BE NEAR OR AT SCA CONDS BY NOW...YET BUOYS 009/010 HAVE DROPPED BELOW 15KT/5FT AFTER THE INITIAL POST-FRONTAL WIND SURGE. WILL ALLOW FOR SOME ADDITIONAL RISE IN WINDS/SEAS WITH PSBL SECONDARY ENE/E WIND INCREASE...BUT NOTHING ABOVE 15KT OR SO AND 6FT WELL OFFSHORE. NO CHOICE BUT TO DISCONTINUE SCA GIVEN CURRENT CONDS. PROGRESSIVE WX PATTERN OVER THE CONUS WILL ALLOW A RIDGE-TROF-RIDGE PATTERN OVER THE SERN U.S. THROUGH THE MIDDLE OF NEXT WEEK. RIDGE AXIS BUILDING OFF THE MID ATLC COAST WILL GENERATE A FRESH TO MODERATE E/SE FLOW OVER THE LCL ATLC WATERS ON SUN. THESE WILL SHIFT TO THE S/SE MON/MON NIGHT AS THE NEXT COLD FRONT PUSHES INTO THE PANHANDLE. FROPA ON TUE WILL ALLOW SW FLOW TO SHIFT TO THE NW...WINDS SHOULD REMAIN BLO SCA CRITERIA BUT WILL GENERATE CHOPPY SEAS OVER THE OPEN ATLC. RIDGE AXIS BUILDING OFF THE MID ATLC COAST BEHIND THE FRONT WILL BRING WINDS BACK AROUND TO THE E/NE BY MIDDAY WED. && .PRELIMINARY POINT TEMPS/POPS... DAB 73 64 80 68 / 10 10 20 10 MCO 78 62 83 66 / 10 10 20 10 MLB 79 68 81 71 / 10 10 20 10 VRB 79 68 81 71 / 10 10 20 10 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM/AVIATION...CRISTALDI LONG TERM....BRAGAW fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 325 AM EST SAT NOV 24 2007 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR SNOW TODAY. WATER VAPOR IMAGERY AND RUC SHOWING A DEEP LOW OVER CENTRAL CANADA WITH AN ACCOMPANYING LONGWAVE TROUGH STRETCHING ACROSS CENTRAL CONUS TO A LOW OVER SOUTHWEST NEW MEXICO. A STEEP RIDGE IS OVER THE PACIFIC NORTHWEST AND THE CANADIAN ROCKIES. ANOTHER TROUGH IS OVER EASTERN CANADA. WEAK SHORTWAVES MIGRATING THROUGH THE TROUGH ARE OVER EAST CENTRAL WISCONSIN AND NORTHERN LOWER MICHIGAN. OTHER SHORTWAVES ARE OVER NORTHERN MANITOBA AND WESTERN SASKATCHEWAN. SURFACE ANALYSIS DEPICTS A LARGE HIGH OVER EAST CENTRAL ATLANTIC STATES WITH A RIDGE STRETCHING WEST ACROSS THE OHIO RIVER VALLEY INTO THE MIDDLE MISSISSIPPI RIVER VALLEY. A DEEP LOW IS OVER WESTERN HUDSON BAY WITH A FRONTAL SYSTEM EXTENDING ACROSS CENTRAL MANITOBA AND CENTRAL SASKATCHEWAN. A WEAK TROUGH WHICH IS A REFLECTION OF THE LONGWAVE TROUGH IS LOCATED OVER MINNESOTA...NORTHWEST IOWA AND EASTERN NEBRASKA. THE LONGWAVE TROUGH WILL SWEEP ACROSS THE FORECAST AREA TODAY AS WILL THE SURFACE REFLECTION. AN 850MB THERMAL TROUGH OVER WESTERN ONTARIO WILL WEAKEN AS IT MOVES INTO LAKE SUPERIOR THIS AFTERNOON. HOWEVER...THE LAKE-850MB DELTA-T WILL STILL BE LARGE ENOUGH TO CAUSE LAKE EFFECT SNOWS. 280K ISENTROPIC ASCENT ACCOMPANYING THE SURFACE TROUGH MOVING THROUGH THE AREA WILL SUPPORT BRING SOME SNOW TO THE AREA. FORECAST SOUNDINGS SHOWING THAT IT WILL BE FAIRLY DRY ABOVE 850MB AND LOW LEVEL MOISTURE WILL BE LIMITED MAINLY TO WHAT COMES FROM THE LAKE. SURFACE WINDS ARE EXPECTED TO BE MAINLY OUT OF THE SOUTHWEST SO MOST OF THE LES WILL OCCUR ON THE CANADIAN SIDE OF LAKE SUPERIOR AND EAST OF THE FORECAST AREA. THE 280K ISENTROPIC WINDS WILL BE A LITTLE MORE WESTERLY THUS THE KEWEENAW PENINSULA COULD STILL GET SOME LAKE EFFECT SNOWS. THE REST OF THE AREA SHOULD ONLY RECEIVE LIGHT AMOUNTS DUE TO THE DRY CONDITIONS. A 40 KNOTS LOW LEVEL JET WILL SHIFT ACROSS THE AREA TODAY. THE STEEP LAPSE RATE OVER LAKE SUPERIOR SUPPORTS MIXING THE WINDS TO SURFACE...WHICH WILL REACH GALE FORCE OVER LAKE SUPERIOR. THE LONGWAVE TROUGH WILL SHIFT TO NORTHERN NEW ENGLAND TONIGHT SETTING UP MORE OF A ZONAL FLOW ACROSS NORTHERN CONUS. MID LEVEL INSTABILITY WILL SHIFT EAST AS WELL. A SHORTWAVE WILL SAIL ACROSS WESTERN CONUS IN THE ZONAL FLOW AND REACH NORTH DAKOTA AND NORTHEAST MONTANA. WARM AIR ADVECTION WILL PUSH THE 850MB THERMAL TROUGH INTO NORTHERN ONTARIO. THE CANADIAN COLD FRONT WILL SETTLE OVER LAKE SUPERIOR AND NORTHERN MINNESOTA TONIGHT. ISENTROPIC ASCENT ACCOMPANYING THIS FRONT COULD GENERATE A MORE SNOW SHOWERS NORTH OF THE FRONT. THE CRITICAL FACTOR HERE WILL THE PLACEMENT OF THE FRONT. THE LOCALLY GENERATE HIGH RESOLUTION WRF CONTINUES TO PLACE THE FRONTAL SYSTEM AND MOISTURE FIELD OVER LAKE SUPERIOR AND THE KEWEENAW PENINSULA. THE REGIONAL CANADIAN IS SUPPORTING THIS SCENARIO AS WELL WHILE THE NAM ALSO SUPPORTS THE FRONTAL POSITION BUT IS A LITTLE DRIER. THUS WILL KEEP THE FORECAST AREA DRY EXCEPT FOR THE KEWEENAW PENINSULA AND CENTRAL AND EASTERN LAKE SUPERIOR TONIGHT. THE LOW LEVEL JET WILL REMAIN OVER LAKE SUPERIOR BUT WILL WEAKEN TO 30 KNOTS OVERNIGHT. A WEAK SHORTWAVE WILL RACE ACROSS LAKE SUPERIOR AND WESTERN PART OF THE FORECAST AREA ON SUNDAY. THE SURFACE LOW AND FRONTAL SYSTEM WILL MOVE TO NORTH CENTRAL LAKE SUPERIOR. MODELS CONTINUE TO SHOW THAT THE BEST CHANCE OF PRECIPITATION WILL BE NORTH OF THE FRONTAL SYSTEM. LAKE SUPERIOR AND THE KEWEENAW PENINSULA WILL CONTINUE TO HAVE SNOW SHOWERS IN THE MORNING. THE NORTHERN PART OF LAKE SUPERIOR WILL HAVE SNOW SHOWERS LATE IN THE AFTERNOON AS PER NAM/GFS/GEM. ONE BRANCH OF THE LOW JET WILL BE OVER WESTERN ONTARIO WHILE THE OTHER IS OVER THE NORTHERN MISSISSIPPI RIVER VALLEY. WINDS OVER THE LAKE WILL BE FAIRLY LIGHT. THE SHORTWAVE WILL RACE ACROSS LAKE SUPERIOR SUNDAY NIGHT...WHILE THE SURFACE LOW RELOCATES OVER EAST CENTRAL ONTARIO. THE FRONT WILL CONTINUE TO BE DRAPED ACROSS THE NORTHERN U.P. AND LAKE SUPERIOR. A HIGH PRESSURE RIDGE WILL PUSH INTO SOUTH CENTRAL CANADA. ANTI CYCLONIC FLOW AHEAD OF THE HIGH WILL DRAW COOLER AIR INTO THE FORECAST AREA FROM CENTRAL CANADA. THE WINDS WILL BE OUT OF THE NORTHWEST OVER THE LAKE AND THE 850MB DELTA-T WILL BE AROUND 14C. FORECAST SOUNDINGS FAVORABLE FOR LAKE EFFECT SNOW OVER THE FORECAST BY SUNRISE. GEM/GFS/ECMWF WILL BRING THE COOLER AIR INTO THE FORECAST AREA ABOUT 6 HOURS EARLIER THAN PREVIOUS SHOWN FOR MONDAY. THUS WILL MOVE UP THE CHANCES OF LAKE EFFECT SNOW BY 6 HOURS. THE WIND DIRECTIONS WILL SHOW WHERE THE FAVORED AREAS OF HEAVIEST LAKE EFFECT SNOWFALL WILL OCCUR. A MID LEVEL LOW WILL SWING OUT OF CENTRAL CANADA ACROSS ONTARIO MONDAY NIGHT INTO WEST CENTRAL QUEBEC ON TUESDAY. THE COOLEST AREA (-22C) OF THE 850MB THERMAL TROUGH WILL TRACK ACROSS ONTARIO LATE MONDAY NIGHT AND TUESDAY. LOW LEVEL MOISTURE IS EXPECTED TO INCREASE. WINDS WILL FAVOR SOME LES. HOWEVER...INSTABILITY WITH THE SHORTWAVE AND SURFACE LOW...AND AVAILABLE MOISTURE WILL GENERATE A FEW SHOWERS WHICH WILL BE ENHANCED WITH THE LAKE EFFECT SNOWS DUE TO THE THERMAL TROUGH MOVING THE ONTARIO. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL AT KSAW THRU THIS FCST PERIOD. THERE MIGHT BE A FEW FLURRIES INTO SAT MORNING...BUT NO VIS RESTRICTION IS EXPECTED. AT KCMX...VFR CONDITIONS WILL PREVAIL WHILE AWAITING THE EVOLUTION OF LAKE EFFECT -SHSN OVER WRN LAKE SUPERIOR. IT REMAINS VERY UNCERTAIN WHETHER THE WINDS WILL VEER WRLY ENOUGH LATE TONIGHT OR SAT MORNING TO BRING LAKE EFFECT SNOW BANDS ONSHORE AS FAR S AS KCMX. SO ONLY PROB30 INCLUDED FOR MVFR VIS IN -SHSN FROM MID MORNING THROUGH THE EARLY AFTERNOON.. CONDITIONS COULD REMAIN VFR OR DROP TO IFR DEPENDING ON VERY SUBTLE CHANGES IN WIND DIRECTION. WHETHER OR NOT SNOW DEVELOPS...WINDS WILL LIKELY BECOME RATHER GUSTY IN THE AFTERNOON. MODELS SUGGEST WINDS WILL VEER MORE WRLY BY LATE AFTERNOON AND EVENING BUT MAY STILL HAVE ENOUGH S COMPONENT TO KEEP ANY MORE SUBSTANTIAL LES BANDS OFFSHORE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... SW WINDS HAVE ALREADY INCREASED TO 30 KT OVER MUCH OF LAKE SUPERIOR DURING THE OVERNIGHT HOURS THANKS TO THE APPROACH OF A TROUGH NOW OVER WESTERN LAKE SUPERIOR. THIS TROUGH WILL DISSIPATE THIS MORNING...HOWEVER LURKING TO THE NW IS A STRONGER TROUGH OVER CENTRAL MANITOBA. AS THIS TROUGH APPROACHES LAKE SUPERIOR THIS AFTERNOON AND EVENING...WINDS SHOULD BE ABLE TO INCREASE TO GALES...WITH SOME GUSTS AROUND 40 KT OVER THE TYPICAL SW FLOW HIGH WIND AREA OF THE TIP OF THE KEWEENAW. WINDS SHOULD RELAX AFTER MIDNIGHT TONIGHT AS THE TROUGH DROPS INTO NORTHERN LAKE SUPERIOR AND BECOMES STATIONARY. A LOW PRESSURE AREA IS EXPECTED TO DEVELOP IN SE SASKATCHEWAN ON SUNDAY AND MOVE ACROSS LAKE SUPERIOR SUNDAY NIGHT. IN THE WAKE OF THIS LOW...NORTH WINDS MAY INCREASE UP TO 25 KT MONDAY MORNING BEFORE A WEAK RIDGE OF HIGH PRESSURE BUILDS IN FOR MONDAY NIGHT. BEYOND MONDAY NIGHT...THE WIND FORECAST IS A LITTLE UNCERTAIN...WITH THE POSSIBILITY OF A QUICK ARCTIC AIR SHOT ON TUESDAY MORNING. IF THIS PANS OUT...WE COULD BE DEALING WITH A BRIEF NW GALE ALONG WITH FREEZING SPRAY. WILL NEED TO KEEP A CLOSE EYE ON THIS. OTHERWISE...ANOTHER LOW PRESSURE AREA IS SHOWN TO MOVE UP INTO THE WESTERN GREAT LAKES REGION ON WEDNESDAY. DEPENDING ON THE EXACT TRACK...ANOTHER N TO NW GALE COULD OCCUR ON THE BACK SIDE OF THE HIGH. AT THE PRESENT TIME...THE MOST LIKELY PERIOD THIS WOULD OCCUR WOULD BE LATE WEDNESDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING 1 PM SAT TO MIDNIGHT EST SAT NIGHT LSZ162-263-264. GALE WARNING 4 PM SAT TO 3 AM EST SUN LSZ265>267. GALE WARNING 4 PM SAT TO 1 AM EST SUN LSZ243-244. && $$ DISCUSSION...DLG AVIATION...JLB MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1234 AM EST SAT NOV 24 2007 UPDATED AVIATION DISCUSSION .UPDATE... MAIN FCST CONCERNS ARE -SN AND POTENTIAL LES OVER THE KEWEENAW. A SHORTWAVE TROUGH FROM NRN ONTARIO INTO NW MN SUPPORTED AN AREA OF LIGHT SNOW OR FLURRIES OVER NE MN INTO FAR NW WI WITH LOWEST VSBYS GENERALLY IN THE 3-5SM RANGE. S TO SW SFC WINDS PREVAILED ACROSS MOST OF THE CWA AHEAD OF A WEAK TROF MOVING THROUGH NE MN. WITH ADDITIONAL PRES FALLS EXPECTED N OF LAKE SUPERIOR TOWARD DAYBREAK AHEAD OF ANOTHER LOW PRES MOVING SE FROM MANITOBA...AND DEVELOPING LAND BREEZES...MAIN CONVERGENT ZONE OVER WRN LAKE SUPERIOR IS EXPECTED TO REMAIN MAINLY OFFSHORE INTO SAT MORNING. SO...POPS WERE LOWERED OVER THE NRN KEWEENAW. OTHERWISE...280K-285 ISENTROPIC ASCENT AHEAD OF THE SHORTWAVE MAY BRING SOME LIGHT SNOW INTO UPPER MI. HOWEVER...WITH A SIGNIFICANT 850-700 DRY LAYER...PER 03Z KSAW TAMDAR SOUNDING...ONLY WEAK LIFT AND LIMITED MOISTURE AVAILABLE...MAINLY FLURRIES ARE EXPECTED WITH LITTLE OR NO ACCUMULATION. && .SHORT TERM (TONIGHT AND SAT)... MAIN FCST ISSUE REVOLVES AROUND LES. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE ALONG THE W COAST OF NAMERICA WITH THE DOWNSTREAM TROF DOMINATING MUCH OF CNTRL/ERN NAMERICA. IN THE NW FLOW...ONE SHORTWAVE IS OVER NRN ONTARIO WITH A STRONGER SHORTWAVE DROPPING TOWARD NRN SASKATCHEWAN/MANITOBA. WAA REGIME IN RESPONSE TO THE ONTARIO SHORTWAVE HAS BROUGHT A BAND OF MID CLOUDS AND STRATOCU INTO UPPER MI TODAY. SOME FLURRIES HAVE ALSO OCCURRED OVER THE WRN FCST AREA. MEANWHILE...THE LOW-LEVEL SW FLOW THAT HAS DEVELOPED HAS SHIFTED WHAT IS LEFT OF LES COMPLETELY OFFSHORE OF UPPER MI. EARLIER TODAY...THERE WAS A DOMINANT BAND CLOSE TO THE N SHORE OF MN EXTENDING NE TO JUST N OF ISLE ROYALE. IT APPEARS MUCH OF THAT BAND HAS BROKEN UP. IT`S DIFFICULT TO TELL WHAT IS HAPPENING NOW AS HIGHER CLOUDS ARE OBSCURING LAKE EFFECT...BUT THERE ARE SOME HINTS THAT LES IS OCCURRING BTWN THE KEWEENAW AND ISLE ROYALE. WITH 850MB TEMPS RISING NO HIGHER THAN -9C TONIGHT...LES WILL CONTINUE TO BE A POSSIBILITY...AND ONGOING SW FLOW WILL ALLOW FOR THE POTENTIAL OF LONG FETCH SW-NE ORIENTED LES BANDS OVER WRN LAKE SUPERIOR. AS SHORTWAVE OVER NRN ONTARIO HEADS ESE...SFC TROF NOW EXTENDING FROM NRN ONTARIO TO FAR NW MN WILL SLIP OVER LAKE SUPERIOR TONIGHT. THIS WILL ENHANCE THE CONVERGENCE...PROMOTING THE DEVELOPMENT OF A DOMINANT BAND ALONG THE TROF. ALL THE MODELS SUGGEST THIS...BUT THE RUC13 AND LOCALLY RUN HIGH RES WRF-ARW ARE MUCH MORE WELL-DEFINED WITH THE BAND. SO THE QUESTION IS...WILL THE WINDS BECOME WRLY ENOUGH TO PUSH THIS BAND TO THE KEWEENAW. CURRENTLY...PRES RISES BEHIND THE SFC TROF ARE WEAKENING TO THE POINT THAT THERE ARE ALMOST NO RISES NOTED IN THE LAST 3HRS...AND PRES FALLS ARE ALREADY INCREASING AND SPREADING S INTO SCNTRL CANADA AHEAD OF THE STRONGER SHORTWAVE DROPPING S IN NRN CANADA. THUS...IT WOULD APPEAR THE TROF/WIND SHIFT WILL NOT MAKE SIGNIFICANT PROGRESS ACROSS THE LAKE. HOWEVER...WITH SOME UNCERTAINTY...WILL KEEP CHC POPS N OF HOUGHTON OVERNIGHT AND JUST BRUSH THE SHORE OF KEWEENAW COUNTY WITH LIKELY POPS AND ABOUT 1 INCH OF ACCUMULATION. EVENING SHIFT WILL PROBABLY BE ABLE TO SHIFT HIGHER POPS OFFSHORE OF THE KEWEENAW IF UPSTREAM PRES FALLS BECOME MORE SIGNIFICANT BEHIND TROF. AS FOR LES NEAR LAKE MICHIGAN...SW FLOW WILL HAVE ENOUGH WRLY COMPONENT TO KEEP ANY LES OFF LAKE MICHIGAN E OF THE FCST AREA. AWAY FROM THE POSSIBLE LES OVER THE KEWEENAW...MAINTAINED A MENTION OF SLIGHT CHC -SHSN OVERNIGHT ACROSS THE FCST AREA AS SFC OBS/RADAR INDICATE SOME -SN/FLURRIES IN THE VCNTY OF SFC TROF. SHORTWAVE CURRENTLY DROPPING TOWARD SASKATCHEWAN/MANITOBA WILL REACH NRN ONTARIO SAT. AS A RESULT...WIND DIRECTION WILL CHANGE LITTLE FOR MOST OF SAT. SO...THE TIP OF THE KEWEENAW REMAINS THE ONLY LOCATION FOR ANY LES CONCERNS. SINCE THERE IS A HINT THAT THE 850MB WINDS TAKE ON A MORE WRLY DIRECTION SAT AFTN...THE POTENTIAL FOR LES ON THE KEWEENAW SHOULD IMPROVE DURING THE DAY. IF LES DOES NOT REACH THAT AREA TONIGHT...IT SHOULD SAT AFTN. GIVEN THE UNCERTAINTY...KEPT SNOW AMOUNTS CONSERVATIVE WITH JUST 1 TO MAYBE 3 INCHES NORTH OF HOUGHTON. LONGER TERM...00Z SUN ONWARD... NAM SHOWING 500 MB FLOW GETTING ZONAL ON SUN AFTER TROUGH AXIS PASSES THROUGH EARLY SAT NIGHT WITH TROUGHING FOR MON. THERE IS A NARROW RIBBON OF MOISTURE ON THE I280K-I295K SURFACES ON THE NAM ACROSS SOUTHERN AND CENTRAL LAKE SUPERIOR SAT NIGHT THAT SHIFTS TO THE NORTH ON SUN. GFS SHOWS THIS AS WELL ON I280K-I300K SURFACES ALONG WITH BOTH MODELS SHOWING SOME WEAK 850-500 MB Q-VECTOR CONVERGENCE WHICH REMAINS ON SUN ACROSS THE CWA. WITH WEST WINDS ON SAT NIGHT THROUGH SUN MORNING...THE KEWEENAW COULD SEE SOME DECENT SNOW WITH A POSSIBLE SEEDER FEEDER MECHANISM SETTING UP TO HELP THE SNOWFALL RATES ALONG. GFS SOUNDINGS FOR KCMX AND KP59 SHOW INVERSION HEIGHTS ABOUT 5000 FEET THEN AND THIS FALLS LATE SAT NIGHT INTO SUN MORNING. PROBLEM LATE SAT NIGHT INTO SUN MORNING IS THERE IS WARMING AT 850 MB FROM -8C TO -10C TO -6C TO -8C BY 12Z SUN AND THEN 850 MB TEMPERATURES WARM MORE AFTER THAT AND THE WIND TURNS SOUTHERLY BY 18Z SUN. LAKE EFFECT COMBINED WITH THE NARROW RIBBON OF MOISTURE IN THE LOW AND MID LEVELS WILL GIVE SNOWFALL AMOUNTS UP TO 6 INCHES SAT NIGHT INTO SUN MORNING OVER THE KEWEENAW WITH THE RIBBON OF MOISTURE CONFINED TO THE NORTHERN CWA AT THAT TIME AND THIS WILL STILL NEED TO BE WATCHED AS THIS COULD BE ADVISORY AMOUNT SNOW OR JUST BELOW ADVISORY DEPENDING ON HOW AND WHERE THE LAKE EFFECT SNOWBAND SETS UP AND IF IT MOVES BACK AND FORTH AT ALL. THIS IS THE ONLY SPOT THAT WOULD SEE SIGNIFICANT SNOW WITH THE LAKE EFFECT COMBINED WITH THE NARROW RIBBON OF MOISTURE. WILL GO UNDERNEATH ADVISORY AMOUNTS FOR NOW AS GFS SOUNDINGS SHOW THE LOWEST LEVELS AGAIN HAVE AN INVERTED-V SOUNDING LOOK TO THEM WITH SOME DRY AIR AND THIS SHOULD CUT INTO AMOUNTS A BIT. OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST EXCEPT TO GO LIKELY OVER THE KEWEENAW PENINSULA WITH THE LAKE EFFECT SNOW BAND AND THE SYNOPTIC MOISTURE AROUND. FOR TEMPERATURES...DID NOT MAKE ANY CHANGES OR VERY LITTLE CHANGE TO THE GOING FORECAST. IN THE EXTENDED...GFS...ECMWF AND CANADIAN MODELS ALL SHOW THE 500 MB PATTERN CONSISTS OF A TROUGH MOVING INTO THE UPPER GREAT LAKES 00Z TUE WITH A SHORTWAVE RIDGE AFFECTING THE AREA 00Z WED. ANOTHER TROUGH MOVES IN FOR 00Z THU AND FOR 00Z FRI WITH RIDGING FOR 00Z SAT. WE END UP GETTING TWO STORMS WITH THE FIRST ON MON AND THE NEXT ON WED AND THU. THE ONE FOR WED AND THU COULD BE A SIGNIFICANT SNOW PRODUCER BEHIND IT WITH LAKE EFFECT SNOW AND STRONG NORTH TO NORTHWEST WINDS. WILL HAVE TO WATCH THIS ONE WITH ITS TRACK ANYWAY. WENT CLOSE TO 06Z GFS AND 00Z ECMWF FOR THIS FORECAST. TEMPERATURES LOOK TO BE COLDER THAN NORMAL IN THE EXTENDED STARTING ON WED AND WENT CLOSE TO ADJMXR FOR LOWS AND HIGHS. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL AT KSAW THRU THIS FCST PERIOD. THERE MIGHT BE A FEW FLURRIES INTO SAT MORNING...BUT NO VIS RESTRICTION IS EXPECTED. AT KCMX...VFR CONDITIONS WILL PREVAIL WHILE AWAITING THE EVOLUTION OF LAKE EFFECT -SHSN OVER WRN LAKE SUPERIOR. IT REMAINS VERY UNCERTAIN WHETHER THE WINDS WILL VEER WRLY ENOUGH LATE TONIGHT OR SAT MORNING TO BRING LAKE EFFECT SNOW BANDS ONSHORE AS FAR S AS KCMX. SO ONLY PROB30 INCLUDED FOR MVFR VIS IN -SHSN FROM MID MORNING THROUGH THE EARLY AFTERNOON.. CONDITIONS COULD REMAIN VFR OR DROP TO IFR DEPENDING ON VERY SUBTLE CHANGES IN WIND DIRECTION. WHETHER OR NOT SNOW DEVELOPS...WINDS WILL LIKELY BECOME RATHER GUSTY IN THE AFTERNOON. MODELS SUGGEST WINDS WILL VEER MORE WRLY BY LATE AFTERNOON AND EVENING BUT MAY STILL HAVE ENOUGH S COMPONENT TO KEEP ANY MORE SUBSTANTIAL LES BANDS OFFSHORE. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... MAIN FCST CONCERN CONTINUES TO BE THE POTENTIAL OF GALES SAT/SAT NIGHT. LATEST ROUND OF FCST GUIDANCE SUPPORTS THE THINKING OF THE LAST COUPLE OF DAYS THAT WSW GALES WILL IN FACT OCCUR SAT AFTN/EVENING AS PRES GRADIENT TIGHTENS AHEAD OF A LOW PRES TROF DROPPING SE TOWARD LAKE SUPERIOR. HAVE THUS ISSUED GALE WARNINGS FOR THE OPEN WATERS OF LAKE SUPERIOR SAT AFTN/NIGHT. BEFORE THE GALES BEGIN...STIFF SW WINDS OF 20-30KT WILL DOMINATE TONIGHT/SAT MORNING WITH THE STRONGEST WINDS PROBABLY BTWN THE KEWEENAW AND ISLE ROYALE. ANOTHER ROUND OF GALES...THIS TIME N TO NW GALES...MAY OCCUR LATE WED AS DEEPENING LOW PRES MOVES NE INTO THE GREAT LAKES REGION. && .MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING 1 PM SAT TO MIDNIGHT EST SAT NIGHT LSZ263-264. GALE WARNING 4 PM SAT TO 3 AM EST SUN LSZ265>267. && $$ UPDATE...JLB SHORT TERM...ROLFSON LONG TERM...GJM AVIATION...JLB MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1202 AM EST SAT NOV 24 2007 .AVIATION...WITH PERSISTENT SW LOW LEVEL WINDS...LAKE EFFECT SNOW WILL CONTINUE TO MAKE A NUISANCE OF ITSELF NEAR PLN...WITH FEWER ISSUES AT TVC/APN. THE MOST SIGNIFICANT SNOW SHOULD BE AT MIDDAY SATURDAY...AS AN UPPER LEVEL DISTURBANCE BRINGS MUCH MORE MOISTURE TO THE REGION. STILL HAVE PREVAILING LIFR CONDITIONS FOR A PERIOD TODAY AT PLN. WITH NEAR FREEZING SURFACE TEMPS...THIS SNOW WILL BE SOMEHWTA HEAVIER/SLUSHIER THAN WE/VE SEEN THE PAST COUPLE OF DAYS. AT TVC/APN...MOST OF THE IMPACT WILL BE THIS AFTERNOON...WITH CONDITIONS LOWERING TO HIGH-END IFR AT TVC FOR A TIME...AND OCCASIONALLY DOWN TO LOW-END MVFR AT APN. FOR SATURDAY NIGHT... CLOUDS/SNOW SHOWERS WILL DIMINISH AT TVC/APN AS THE UPPER DISTURBANCE PULLS AWAY. PLN WILL STILL SEE SNOW SHOWERS OFF OF LAKE MI...BUT NOT AS SIGNIFICANT AS DURING THE DAY. JZ && .UPDATE...ISSUED 948 PM FRI NOV 23... LAKE EFFECT SNOW (LES) EXPERIENCED A LULL IN THE LATE AFTERNOON/EARLY EVENING. SINCE THEN...A DOMINANT BAND HAS TRIED TO REORGANIZE...FROM CROSS VILLAGE TO BOIS BLANC ISLAND...AND IS VERY SLOWLY DRIFTING SOUTHWARD. THIS IS NORTH OF WHERE THE HEAVIER SNOW FELL DURING THE DAY. THIS BAND IS NOT YET ESPECIALLY IMPRESSIVE...AS SYNOPTIC-SCALE MOISTURE AND FORCING IS LACKING. HOWEVER...THERE IS A FAIRLY IMPRESSIVE AREA OF SURFACE CONVERGENCE THAT HAS DEVELOPED OVER THE TIP OF THE MITT...WITH MAINLY SOUTH WINDS OVER NORTHERN LOWER MI...AND WSW WINDS ON BEAVER ISLAND AND THE NORTHERN LK HURON BUOY. FOR THE OVERNIGHT...WILL BE INTERESTING TO SEE IF THE CONVERGENCE ZONE CAN HOLD TOGETHER AS THE PRESSURE GRADIENT TIGHTENS...AHEAD OF THE MAIN COLD FRONT HEADING TOWARD THE CANADIAN PRAIRIE. IF IT CAN...1000-850MB CONVERGENCE WILL STRENGTHEN...AND SO SHOULD THE LES BAND. MIXED SIGNAL FROM THE SHORT-TERM MODELS. THE RUC STRENGTHENS LOW-LEVEL CONVERGENCE WITH TIME...BUT MAINLY BECAUSE ITS SURFACE WIND FIELDS ARE TOO WEAK IN THE HERE AND NOW (ESPECIALLY OVER LAKE MI). THE NAM IS INCLINED TO WEAKEN CONVERGENCE WITH TIME...BUT IT IS ALSO STRUGGLING WITH THE SURFACE WIND FIELDS...WHICH ARE NOT BACKED ENOUGH OVER LAND. AM INCLINED TO THINK THAT SURFACE WINDS WILL REMAIN RELATIVELY BACKED OVER LAND AREAS THRU THE NIGHT. OUTSIDE OF MAIN LES AREAS...CLOUD COVER IS PATCHY/THIN AND HAS HELPED IN KEEPING THE LOW LEVEL WINDS FROM FULLY COUPLING. WITH THAT THOUGHT IN MIND...LES BAND SHOULD STRENGTHEN...THOUGH IT WILL ALSO CONTINUE TO WOBBLE A BIT AS 1000-850MB WINDS SHIFT (SLIGHT BACKING THIS EVENING...SLIGHT VEERING OVERNIGHT...AT LEAST IF THE NAM IS TO BE BELIEVED). OVERALL...HAVE DIMINISHED THE HIGHEST SNOWFALL AMOUNTS IN EMMET COUNTY A BUT...WITH AROUND 4 INCHES OR SO IN THE NORTH HALF OF THE COUNTY. HAVE INCREASED SNOW AMOUNTS DOWNSTREAM...IN FAR NORTHERN CHEBOYGAN COUNTY...AND OUT TOWARD DE TOUR/DRUMMOND. THESE CHANGES WILL PROMPT AN LES ADVISORY FOR NORTHERN CHEBOYGAN CO...WHICH WILL RUN THRU 7 PM SATURDAY. SPEAKING OF WHICH...WILL BUMP UP SNOW AMOUNTS A BIT FOR SATURDAY. SURFACE TEMPS WILL BE ON THE WARM SIDE (AT LEAST INITIALLY). BUT AS THE BETTER FORCING ARRIVES AT MIDDAY (STILL COINCIDENT WITH DELTA T/S AROUND 17C)...BANDED LES OFF THE LAKE SHOULD BE SUFFICIENTLY STRONG TO LOWER SURFACE TEMPS BACK TO AROUND FREEZING. ELSEWHERE IN THE REGION...HAVE ALREADY LOWERED MIN TEMPS A BIT IN SOME SPOTS (LIKE GRAYLING). HOWEVER...WITH WINDS INCREASING WITH TIME...SUSPECT MOST PLACES ARE NEAR (OR HAVE ALREADY SEEN) THEIR LOWS FOR THE NIGHT. ZOLTOWSKI && .PREVIOUS DISCUSSION...ISSUED 404 PM FRI NOV 23... PRIMARY FORECAST CHALLENGE OVER THE NEXT 24 HOURS REMAINS LAKE EFFECT/ENHANCED SNOWFALL AND AMOUNTS...AND WHAT/IF ANY HEADLINES MAY BE NEEDED. EARLY AFTERNOON ANALYSIS PLACES MUCH OF NORTHERN MICHIGAN ON THE BACKSIDE OF LOW LEVEL RIDGE AXIS EXTENDING FROM THE MID MISS VALLEY UP THROUGH EASTERN ONTARIO...WHILE ALOFT...WEAK SHORTWAVE RIDGING BUILDING ACROSS THE REGION IN ADVANCE SHORTWAVE ENERGY DROPPING THROUGH THE NORTHERN HIGH PLAINS. OVERALL LOW LEVEL FLOW REGIME HAS BEEN IN TRANSIT THROUGH THE DAY...STARTING NORTH/NORTHWEST AND ENDING UP MORE WEST/SOUTHWEST AS OF 19Z...WITH A CORRESPONDING SHIFT IN LAKE EFFECT SNOW SHOWERS TOWARD THE WSW FAVORED LOCATIONS. DESPITE RATHER SCANT 900-700MB MOISTURE INITIALLY...LATEST RUC/SATELLITE ANALYSIS SHOWS AN UPTICK IN BOUNDARY LAYER RH GIVEN INCREASINGLY LONG FETCH ACROSS LAKE MICHIGAN. SNOWFALL AMOUNTS THROUGH THE DAY HAVE BEEN RATHER IMPRESSIVE IN A FEW SPOTS...NAMELY OWING TO PRONOUNCED STUBBORN LOW LEVEL CONVERGENCE AS A WEAK WARM FRONT SNUCK ITS WAY NORTH THROUGH THE DAY. BIGGEST WINNERS SO FAR - CHARLEVOIX AND EMMET COUNTIES...WHERE SEVERAL REPORTS OF 3 TO AS MUCH AS LOCALLY 5 INCHES HAVE BEEN NOTED...VERY MUCH IN LINE WITH LATEST KAPX RADAR STORM TOTAL SNOW GRAPHICS. FOR TONIGHT...OVERALL PATTERN PROGGED TO CHANGE VERY LITTLE AS PERSISTENT WEST TO SOUTHWESTERLY FLOW REMAINS INTACT AHEAD OF APPROACHING LOW/MID LEVEL TROUGH. PLENTY OF OVER-LAKE INSTABILITY TO WORK WITH (OBVIOUSLY GIVEN ONGOING SNOWS)...WITH H85 TEMPS PROGGED TO "WARM" JUST SLIGHTLY TO AROUND -10C BY 12Z TOMORROW. 900-700MB RH ALSO QUITE CONDUCIVE FOR LES...WITH VALUES ON THE RISE TO 80 PERCENT OR BETTER OVERNIGHT PER CONTINUED LONG FETCH UP LAKE MICHIGAN. DIFFICULT TO FIND ANY REASON WHY SNOWS WON/T CONTINUE THROUGH MUCH OF THE NIGHT AS WEST/SOUTHWEST FLOW HOLDS STATUS QUO...AND INCREASING GRADIENT ACTS TO PREVENT ANY LAND BREEZES THAT COULD POTENTIALLY TRY TO SHOVE ANY SNOW BANDS FARTHER OFFSHORE. USING THE 15Z SREF POP MEAN AS GUIDANCE...WILL HANG THE HIGHEST POPS ACROSS EMMET AND SOUTHERN MACKINAC COUNTIES (I.E. W/SW FLOW AREAS)...AND WILL RUN WITH A WARNING ACROSS EMMET (GIVEN ALREADY SNOWY CONDITIONS THIS AFTERNOON) AND AN ADVISORY FOR MACKINAC (WITH A HIGHER CRITERIA FOR WARNING). HEADING INTO TOMORROW...UPPER WAVE PROGGED TO SWING THROUGH THE REGION BETWEEN 15Z AND 21Z...WITH AXIS OF DECENT 700-500MB -DIVQ AND MUCH DEEPER PLUME OF MOISTURE (1000-500MB RH INCREASES TO BETTER THAN 90 PERCENT) ANNOUNCING THE LIKELIHOOD OF A SYNOPTIC COMPONENT TO THE EVENT. CONTINUED WEST/SOUTHWEST LOW LEVEL FLOW REGIME SHOULD EASILY CONTRIBUTE TO ENHANCEMENT ACROSS THE STRAITS REGION...HOWEVER WILL BE DEALING WITH SOME POSSIBLE PTYPE ISSUES ALONG THE IMMEDIATE COAST GIVEN LONG PERIOD OF ONSHORE FLOW...WITH FORECAST RAOBS INDICATING FREEZING LEVELS ABOUT 1500 FT AGL. SOME QUESTION WHETHER THIS WILL BE SUFFICIENT FOR MELTING...AND PROBABLY DEPENDENT ON INTENSITY OF PRECIP. HOWEVER...FOR SIMPLICITY...WILL HOLD PRECIP ALL SNOW. OUTSIDE OF THE LAKE ENHANCEMENT...OVERALL INCREASING SYNOPTIC SUPPORT SHOULD BE SUFFICIENT TO GENERATE SOME LIGHT SNOW FROM WEST TO EAST AS -DIVQ AXIS ADVANCES ACROSS NORTHERN MICHIGAN...BUT DOUBTFUL OF MUCH IN THE WAY OF ACCUMULATION GIVEN EXPECTED HIGHS IN THE LOWER/MIDDLE 30S UNDER INCREASING LOW LEVEL WARM ADVECTION AND OVERALL WEAK FORCING. ON THE MARINE SIDE...INCREASINGLY GUSTY WINDS AND BUILDING WAVES EXPECTED ON THE LAKE MICHIGAN SIDE LATE TONIGHT AND ESPECIALLY TOMORROW MORNING AS GRADIENT TIGHTENS...WITH WINDS AT THE TOP OF THE INSTABILITY-MIXED LAYER RUNNING ABOUT 35-40 KNOTS. COUPLED WITH COASTAL CONVERGENCE SHOULD EASILY SEE GUSTS IN THE GALE RANGE...WITH GALE CONDITIONS SPREADING TO OTHER NEARSHORE AREAS BY EARLY AFTERNOON AS CORE OF STRONGER 900-850MB WINDS SPREADS EAST. LAWRENCE SATURDAY NIGHT INTO SUNDAY...SOUTHWEST FLOW LAKE EFFECT IS EXPECTED TO WIND DOWN SATURDAY NIGHT AS THE SHORTWAVE TROUGH MOVES EAST OF THE REGION. 850-700MB RH FALLS FROM 55-65 PCT AT 00Z SUN TO 45-55 PCT BY 12Z AND INVERSION HEIGHTS LOWER FROM AROUND 6KFT TO ABOUT 3KFT OVER THAT SAME TIME PERIOD. THIS ALL POINTS TO A DIMINISHING TREND OF LES ACTIVITY WITH MOST ACCUMULATIONS ARRIVING DURING THE EVENING AND WILL GO UP TO A HALF INCH OVER SOUTHERN MACKINAC AND NORTHERN EMMET COUNTIES. MID-LEVEL DRY AIR WILL CONTINUE TO POUR INTO THE AREA ON SUNDAY AS 850MB TEMPS MODERATE BETWEEN -3C TO -6C IN THE MORNING TO NEAR 0C BY EARLY IN THE EVENING. BELIEVE ANY LINGERING LOW LEVEL INSTABILITY WILL BE TOO SHALLOW FOR ANY LES ACTIVITY AND WILL KEEP SNOW CHANCES OUT OF THE FORECAST. MOISTURE ALONG THE LOW LEVEL BAROCLINIC ZONE WILL MOVE NE INTO ONTARIO AS WILL MID-UPPER LEVEL MOISTURE ALONG THE SOUTHERN FRINGES OF THE JET STREAM. SO WITH THE DEPARTING MOISTURE ACROSS THE NORTHERN CWA...LOOKS LIKE SOME SUNSHINE WILL BE HAD ON SUNDAY WITH HIGHS RANGING FROM THE UPPER 30S NORTH TO MID 40S SOUTH. SUNDAY NIGHT INTO MONDAY...SURFACE LOW PRESSURE AHEAD OF A MID- LEVEL WAVE OVER THE NORTHERN PLAINS WILL TRACK ALONG ITS WARM FRONT ACROSS SOUTHERN ONTARIO. AHEAD OF THE SURFACE LOW...SW WINDS WILL BRING RELATIVELY WARM AIR (850MB TEMPS BETWEEN -3C AND 0C) INTO MICHIGAN...WHICH WILL LEAD TO LOWS IN THE UPPER 20S TO MIDDLE 30S. DRY AIR OVER THE AREA SUNDAY NIGHT WILL EVENTUALLY LOSE OUT TO INCREASING MOISTURE AHEAD OF A NE MOVING SURFACE LOW OUT OF THE SOUTHERN PLAINS...WHICH GETS PICKED UP BY THE AFOREMENTIONED PACIFIC WAVE. THIS LOW WILL TRAVEL INTO THE LOWER OHIO RIVER VALLEY BY MIDDAY TO CENTRAL OHIO BY 00Z TUE. NORTHERN PERIPHERY OF THE DEFORMATION ZONE ON THE NW SIDE OF THE LOW STILL LOOKS TO CLIP COUNTIES NEAR SAGINAW BAY. STILL HARD TO SAY IF PRECIP WILL MAKE HERE SINCE INITIAL DRY AIRMASS WILL NEED TO BE OVERCOME. WILL TAKE OUT PRECIP CHANCES FOR THE MORNING DUE TO THIS REASON BUT WILL LEAVE A LOW CHANCE OF RAIN FOR THE AFTERNOON GIVEN 850MB TEMPS AROUND 0C AND SURFACE TEMPS AROUND 40F. PASSAGE OF AN 850MB TROUGH DURING THE AFTERNOON WILL HELP SWITCH THE WINDS TO THE NW AND ADVECT IN COOLER AIR...BUT NOT COOL ENOUGH FOR LAKE EFFECT PRECIP TO BE GENERATED. HIGHS WILL BE IN THE UPPER 30S TO LOW 40S. TUESDAY THROUGH FRIDAY...MODELS HAVE A LITTLE BETTER HANDLE ON THE NEXT SW LOW DUE TO PASS ACROSS THE OHIO VALLEY ON MONDAY AND INTO THE EASTERN GREAT LAKES ON TUESDAY...BUT STILL HAVE THEIR DIFFERENCES...SPECIFICALLY WITH THE SPEED OF THE SYSTEM. BEYOND TUESDAY...LOW CONFIDENCE EXISTS WITH LOW PRESSURE DEVELOPMENT MID TO LATE NEXT WEEK. PUT HIGHER FAITH IN THE ENSEMBLES THAN ANY ONE PARTICULAR MODEL RUN. TUESDAY...LOW PRESSURE WILL MOVE FROM THE OHIO RIVER VALLEY NE INTO NEW ENGLAND. THE 06Z GFS IS ON THE NORTHERN EDGE OF ENSEMBLE MEMBERS WHILE THE 00Z ECMWF IS ON THE QUICKER SIDE...SO TRIED TO TAKE A MORE CONSENSUS TRACK. THIS WOULD PLACE THE SOUTHEAST CWA ON THE EDGE OF THE DEFORMATION ZONE MONDAY NIGHT. AN INVERTED TROUGH WILL EMANATE FROM THIS LOW AND MOVE ACROSS THE CWA AS THE SURFACE LOW PASSES TO OUR SE. WINDS BEHIND THIS TROUGH WILL SWITCH TO THE NW AND BRING IN COLDER AIR WHICH HAS THE CHANCE TO START UP LAKE EFFECT PROCESSES. 06Z GFS IS ON THE COLDER EDGE OF GUIDANCE AND WILL TEMPER EXPECTATIONS ON HOW QUICK THE COLDER AIR MOVES IN...ESPECIALLY SINCE 00Z GFS ENSEMBLE HAS SLOWED THE PROGRESSION OF THE COLDER AIR INTO THE AREA. BUT WITH THE GENERAL LOW LEVEL CYCLONIC FLOW...AND QUESTION MARKS WITH LAKE EFFECT PROCESSES...WILL LEAVE A GENERAL LOW CHANCE POP MONDAY NIGHT. MEANWHILE...NORTHERN STREAM ENERGY ROTATING AROUND THE POLAR VORTEX WILL SKIRT BY TO THE NORTH WITHOUT MUCH IMPACT. ALTHOUGH THE CORE OF THE COLD AIR WILL SKIRT BY TO THE NORTH...COLD AIR ADVECTION WILL CONTINUE DURING THE DAY AS 850MB TEMPS FALL INTO THE LOWER TEENS. HOWEVER...VERY DRY AIR WILL POUR INTO THE NORTHERN GREAT LAKES BEHIND THE SURFACE LOW...AND DO NOT EXPECT A LARGE LAKE EFFECT EVENT. HIGHS WILL BE IN THE MIDDLE TO UPPER 30S. WEDNESDAY...HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE STATE. ANY LIGHT LAKE EFFECT WILL CONTINUE INTO TUESDAY NIGHT...WHILE MID-HIGH CLOUDS WILL STREAM ACROSS THE AREA WITH SW ALOFT. DRY LOW LEVELS WITH THE SURFACE RIDGE AXIS PRESENT WILL TRY TO KEEP THE AREA PRECIP FREE DESPITE 850MB TEMPS AROUND -10C. SO WILL GO WITH A DRY BUT MOSTLY CLOUDY DAY WITH HIGHS IN THE LOWER TO MIDDLE 30S. THURSDAY THROUGH FRIDAY...CONFIDENCE LOW DURING THIS PERIOD...ALL STEMMING FROM THE STRENGTH OF SURFACE LOW AS THE NEXT PACIFIC WAVE EMERGES FROM THE ROCKIES. 06Z GFS/00Z ECMWF LEAVE THE DOOR OPEN FOR A STRONGER SURFACE WAVE THAT WOULD PASS ACROSS THE CENTRAL GREAT LAKES WEDNESDAY NIGHT...BUT THEIR SOLUTIONS DO NOT HAVE MUCH SUPPORT FROM THE GFS ENSEMBLE MEMBERS. WILL INCREASE POPS HEADING INTO THURSDAY AS SOME SORT OF SURFACE FEATURE PASSES TO THE SOUTH...THEN KEEP A CHANCE OF SNOW FOR FRIDAY FOR THE LAKE EFFECT SNOW BELTS AS COLDER AIR WRAPS IN BEHIND ANY SYSTEM. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST SATURDAY FOR MIZ015-017. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SATURDAY FOR MIZ016. LM...GALE WARNING FROM 7 AM SATURDAY TO 11 AM EST SUNDAY FOR LMZ323- 341-342-344>346. LH...GALE WARNING FROM 7 AM SATURDAY TO 11 AM EST SUNDAY FOR LHZ345>349. LS...GALE WARNING FROM 7 AM SATURDAY TO 5 AM EST SUNDAY FOR LSZ321- 322. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 412 AM CST SAT NOV 24 2007 .DISCUSSION... THE MAIN FORECAST CONCERNS ARE CLOUD COVER TODAY AND SNOW CHANCES DURING THE EARLY/MIDDLE PORTIONS OF NEXT WEEK. 0930Z SAT WATER VAPOR IMAGERY SHOWS THE MID LEVEL TROUGH AXIS PUSHING ACROSS MN. ATTENDANT STRATUS DECK...WHICH MODELS HAVE A VERY POOR HANDLE ON...EXTENDS FROM CENTRAL MN BACK TOWARD THE CENTRAL DAKOTAS. SNOW SHOWERS CORRELATE WITH THE 20-25 DBZ ECHOES ON THE MPX RADAR...AND RUC/NAM/GFS PROGGED LIFT BETWEEN 850-700MB. WHILE THIS WEAKENS SOMEWHAT THIS MORNING...SCATTERED FLURRIES ARE STILL EXPECTED THIS MORNING...ESPECIALLY ACROSS EAST CENTRAL MN AND WEST CENTRAL WI. AS MENTIONED BEFORE...NO MODEL IS CAPTURING THE LOW LEVEL MOISTURE PROFILES ADEQUATELY THIS MORNING. MORE SPECIFICALLY...THE 00Z/24 GFS PROGGED 925MB LEVEL RH VALUES OF 45 PERCENT ACROSS EASTERN NORTH DAKOTA AT 06Z...WHERE AN OVERCAST DECK CIRCA 3K FEET WAS REALIZED. ALTHOUGH THE RH PROG WAS TOO DRY...THE 11-3.9 MICRON CHANNEL ON SATELLITE WAS BEGINNING TO SHOW THE DEVELOPMENT OF A DRY WEDGE EXPANDING INTO EASTERN NORTH DAKOTA. THEREFORE...THINK THAT THE GFS MAY BE ONTO SOMETHING...AND MAY SEE MORE CLEARING OCCURRING AHEAD OF THE BACK EDGE AS SUBSIDENCE OCCURS IN THE WAKE OF THE SHORTWAVE TROUGH. HAVE STILL GONE MORE PESSIMISTIC ON THE SKY COVER FOR TODAY...WITH CLOUDY TO MOSTLY CLOUDY CONDITIONS UNTIL THIS AFTERNOON. DUE TO THE CLOUD COVER CONCERNS...AND PERSISTENCE OVER THE LAST SEVERAL DAYS...HAVE ALSO UNDERCUT NUMERICAL GUIDANCE FOR TODAY...WITH HIGHS IN THE MID/UPPER 30S EXPECTED. IN THE WAKE OF THE TROUGH...WESTERLY/ZONAL FLOW DEVELOPS OVER THE REMAINDER OF THE WEEKEND. 925MB TEMPERATURES MODERATE TO +4 CELSIUS ACROSS MUCH OF THE CENTRAL/SOUTHWEST ON SUNDAY AFTERNOON. ANTICIPATE MOST OF THE CWA TO WARM IN THE MID/UPPER 40S ON SUNDAY...WITH BREEZY SOUTHWEST WINDS AND MOSTLY CLEAR SKIES YIELDING DECENT MIXING POTENTIAL. A FEW 50 DEGREE READINGS ARE NOT OUT OF THE QUESTION. BOTH GFS/ECMWF MODELS FEATURE A SHORTWAVE DIPPING DOWN FROM CANADA INTO THE NORTH CENTRAL CONUS ON TUESDAY/WEDNESDAY. WHILE THE AGREEMENT ON THE SURFACE TRACK/STRENGTH IS STILL UNCERTAIN...THE MAJORITY OF MEDIUM RANGE MODEL SOLUTIONS ARE INDICATIVE/SUPPORTIVE OF 30 POPS FOR SNOW FROM LATE TUESDAY THROUGH WEDNESDAY. && .AVIATION.../06Z TAF ISSUANCE/ VARIABLE CIGS ACROSS THE AREA AT 05Z WITH SEVERAL LAYERS IN THE 4 TO 9 KFT RANGE. EXPANSIVE AREA OF LOWER CLOUD COVER MAKING GRADUAL PROGRESS SOUTHEAST. UPPER WAVE SEEMS TO BE WEAKENING AS IT RUNS INTO MORE CONFLUENT FLOW ALOFT AS EVIDENCED BY WATER VAPOR IMAGERY AND DECREASING RETURNS ON RADAR. A FEW REPORTS OF LIGHT SNOW AROUND KAXN AND FURTHER NORTH BUT NOT MUCH ELSE. AREA OF HIGH AND MID LEVEL CLOUDS OVER SOUTHERN MINNESOTA AND WEST CENTRAL WISCONSIN MAY HELP SEED LOWER CLOUDS AS THEY MOVE UNDERNEATH ALLOWING ADDITIONAL LIGHT SNOW OR FLURRIES TO DEVELOP. THUS WILL CONTINUE TO CARRY TEMPO GROUPS FOR LIGHT SNOW BUT HAVE KEPT VIS RESTRICTIONS TO 5 OR 6 MILES. CIGS WILL BE MORE CHALLENGING. UPSTREAM OBS AND SATELLITE TRENDS SUPPORT MVFR CIGS WORKING INTO CENTRAL MINNESOTA OVER THE NEXT SEVERAL HOURS BUT MAY STAY JUST NORTH OF KRWF WHERE LOWER END VFR CIGS SHOULD BE DOMINANT. EXPECT THE MVFR CIGS TO LAST THROUGH DAYBREAK WHEN WINDS IN THE CLOUD BEARING LAYER BECOME MORE WESTERLY AND HELP TO ERODE THE REAR FLANK. CLOUD COVER MAY LAST MORE TOWARDS MIDDAY IN WEST CENTRAL WISCONSIN. EXPECT VFR CONDITIONS AT ALL SITES IN THE AFTERNOON WITH SOUTHWESTERLY WINDS INCREASING WITH OCCASIONAL GUSTS TO AROUND 25 KTS FOR A SHORT TIME IN THE AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ LS/MDB mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1038 PM CST FRI NOV 23 2007 .UPDATE... NEW TEXT PRODUCTS AND GRIDS SENT. && .DISCUSSION... OVERALL FORECAST REMAINS IN GOOD SHAPE WITH MINOR TWEAKS FOR EXPECTED SNOWFALL AMOUNTS TONIGHT. UPPER THROUGH MOVING THROUGH THE REGION WITH 80 METER HEIGHT FALLS ALOFT ALONG WITH A 90KT 30MB JET WILL PUSH PRECIP NOW OCCURRING ACROSS SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS INTO OUR CWFA. DRY WEDGE AT 700MB SHOULD LIMIT NORTHWARD EXTENT OF THE THE PRECIP...ALTHOUGH THERE COULD BE A COUPLE OF FLURRIES NORTH OF I80 AS SOME MID LEVEL MOISTURE MOVES IN FROM THE DAKOTAS. COBB FORECAST METHOD SUGGESTS A LITTLE OVER AN INCH IN OUR FAR SWRN CWFA FROM SEWARD TO FAIRBURY TO BEATRICE. DIRECT MODEL OUTPUT FROM NAM/GFS/RUC ALL IN SIMILIAR RANGE...WITH MUCH LOWER AMOUNTS AS YOU MOVE NORTH AND EAST FROM THIS POINT. THUS UPPED THE SNOW TOTALS ALONG THE NE/KS BORDER TO 2 INCHES...AND DID TAPER THE SNOW BACK A BIT IN THE KOMA VICINITY AND ACROSS SWRN IOWA. && .AVIATION... BEST SNOW WILL BE SOUTH OF THE TAF FORECAST SITES WITH KLNK HAVING THE BEST PROBABILITY FOR SEEING ANY TYPE OF VISIBILITY RESTRICTIONS. DON`T THINK ANY SNOW WILL AFFECT KOFK WITH LITTLE MORE THAN FLURRIES AFFECTING KOMA...THUS LITTLE IF ANY VSBY RESTRICTION HERE. && .PREV DISCUSSION... /ISSUED 250 PM CST FRI NOV 23 2007/ SHORT TERM...TONIGHT THROUGH MONDAY SNOW CHANCES TONIGHT THEN TEMPERATURES THROUGH MONDAY WILL BE THE PRIMARY FORECAST CONCERNS. INITIAL PART OF THE FORECAST WILL FOCUS ON TIMING OF A COUPLE OF UPPER LEVEL WAVES. ONE COMING ACROSS THE NORTHERN PLAINS TODAY AND THE SECOND OVER THE FOUR CORNERS AREA. BETTER MOISTURE ASSOCIATED WITH THE SWRN SYSTEM WHERE REGIONAL RADARS SHOW WIDESPREAD SNOW ACROSS WESTERN KANSAS INTO SOUTHWESTERN NEBRASKA. SHORT RANGE MODELS HAVE SIMILAR SOLUTION IN MOVING THE SNOW EAST TONIGHT AS PIECE OF ENERGY FROM THIS SYSTEM SHEARS OFF ACROSS KANSAS. BOTH NAM AND GFS DIG SWRN WAVE SOUTH AND CLOSE OFF AN UPPER LOW OVER NORTHERN MEXICO ON SATURDAY WHILE NORTHERN STREAM WAVE MOVES THROUGH THE REGION AND WEAKENS. THIS IS EXPECTED TO LIMIT TEMPORAL AND SPACIAL EXTENT OF SNOW TO 03Z-12Z TONIGHT AND ACROSS ABOUT THE SOUTH HALF OF THE CWA WITH AMOUNTS RANGING FROM UP TO AN INCH ALONG THE SOUTHEAST NEBRASKA BORDER TO A TRACE ALONG THE PLATTE RIVER AND SOUTH OF I-80 IN WESTERN IOWA. AS SOUTHERN SYSTEM INTENSIFIES ON SATURDAY AND NORTHERN STREAM WAVE MOVES THROUGH...MID LEVEL MOISTURE BECOMES CUT OFF ACROSS THE AREA WITH RAPID END TO THE SNOW. LOW LEVEL MOISURE HOWEVER IS EXPECTED TO REMAIN THROUGH MUCH OF THE DAY SATURDAY IN THE FAR SOUTH. THE EXPECTED SNOWFALL AND CLOUDS EXPECTED TO LIMIT TEMPERATURES AND HAVE TRENDED TOWARD THE COLDER MET GUIDANCE. THE SOUTHERN STREAM SYSTEM WILL REMAIN A CONCERN LATE SUNDAY INTO MONDAY AS IT LIFTS NORTHEAST TOWARD MISSOURI WITH FAR SOUTHEAST NEBRASKA ON THE NORTH EDGE OF PRECIP SHIELD. HAVE ADDED SOME SLIGHT POPS FOR NOW FOR THE EXTREME SOUTHEAST CORNER OF NEBRASKA. TEMPERATURES EXPECTED TO MODERATE ON SUNDAY IN ADVANCE OF SURFACE TROUGH MOVING INTO WESTERN NEBRASKA THEN RETURN TO COOLER TEMPS WITH NEXT COLD FRONT MOVING THROUGH ON MONDAY. LONG TERM...MONDAY NIGHT THROUGH FRIDAY GFS AND PARTICULARLY ECMWF SHOWING LOUSY CONSISTENCY IN THE EXTENDED PERIODS. NEEDLESS TO SAY CONFIDENCE QUITE LOW. FOLLOWING ALONG WITH HPC GUID...MAIN CONCERN IS POSSIBLE SNOW BEGINNING TUESDAY AND INTO WEDNESDAY. ALL THIS HINGES UPON TIMING OF PACIFIC NW WAVE THAT EVENTUALLY MOVES ONTO THE PLAINS EARLY WEDNESDAY MORNING. INCREASING DPVA WITH MID LAYER WAA COMBINE TO INCREASE LIFT THRU THE DAY ON TUESDAY AS WESTERN CONUS TROF DIGS SOUTHWARD THRU THE GREAT BASIN...RESULTING IN CYCLOGENESIS INVOF WESTERN KS. SLY LLVL FLOW AHEAD OF THE SFC LOW HELPS PULL SOME MOISTURE BACK INTO THE PLAINS BEFORE A STRONG COLD FRONT PUSHES ACROSS THE CWA WEDNESDAY MORNING. THE GFS SHOWS NRN AND SRN STREAM FLOW EVENTUALLY PHASING LATE WED ALLOWING A QUICK EXIT OF THE SYSTEM. MODEL CONSISTENCY TOTALLY BREAKS DOWN BY FRIDAY BETWEEN THE GFS/ECMWF. THE GFS ADVERTISES BROAD TROF COVERING THE WRN/CNTRL CONUS WHILE THE ECMWF PLACES A WELL AMPLIFIED TROF FROM THE ROCKIES TO THE SW CONUS. AT THIS POINT THINK ITS BEST TO JUST GO WITH TOKEN POPS FRIDAY UNTIL MODELS BECOME MORE CLEAR. AVIATION... A PIECE OF AN UPPER LEVEL LOW NEAR THE FOUR CORNERS WILL SHEAR OUT OVER THE CNTRL PLAINS BY 12Z SAT AS IT LIFTS NEWD AND MERGES WITH A NRN STREAM TROUGH. THIS SYSTEM WILL SPREAD SOME LIGHT SNOW AND CIGS THAT COULD DROP INTO THE IFR RANGE AFT 06Z IN SERN NEBRASKA...INCLUDING THE LNK VCNTY AND POSSIBLY AS FAR N AS OMA. VSBYS IN THE LIGHT SNOW WILL LIKELY DROP BELOW 3 MILES. ALTHOUGH SNOW CHCS SHOULD END BEFORE 18Z...LOW CLOUDS COULD LINGER UNTIL AFT 18Z IN ERN NEBRASKA AND SWRN IA. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ DEWALD ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 254 AM EST SAT NOV 24 2007 .SYNOPSIS... HIGH PRESSURE WILL MOVE INTO THE REGION TONIGHT...BRINGING COLD OVERNIGHT LOW TEMPERATURES...AND HELPING TO END ANY REMAINING LAKE EFFECT SNOW SHOWERS. A WEATHER SYSTEM WILL PASS NORTH OF THE REGION ON SATURDAY...AND BRING CONSIDERABLE HIGH CLOUDINESS TO MUCH OF CENTRAL NEW YORK AND NORTHEAST PENNSYLVANIA...WITH TEMPERATURES CONTINUING TO BE BELOW SEASONAL NORMS. A MODERATING TREND WILL BEGIN ON SUNDAY WITH OUR NEXT WEATHER MAKER BRINGING RAIN TO THE REGION ON MONDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... ALTHOUGH LAKE EFFECT SNOWS ARE STILL ONGOING...THEIR INTENSITY HAS DIMINISHED CONSIDERABLY AS WE HEAD INTO THE LATE EVENING HOURS. REGIONAL SOUNDINGS FROM 00Z SHOW A FAIRLY DRY BOUNDARY LAYER...A LOWERING INVERSION BASE...AND INCREASED SHEAR. ALL OF THIS HAS TAKEN ITS TOLL ON THE EARLIER LAKE SNOW BANDS. BASED ON THE LATEST RUC MODEL GUIDANCE...THE LOW-LEVEL RIDGE AXES SHOULD BE PASSING CENTRAL NY TOWARDS DAYBREAK...SO WE EXPECT FLURRIES TO PERSIST ABOUT UNTIL THAT TIME...WITH LITTLE ADDITIONAL ACCUMULATION ANTICIPATED. SNOW SHOULD END ALTOGETHER AFTER SUNRISE. ONCE AGAIN...WE MASSAGED THE SKY COVER AND TEMPERATURE GRIDS. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... NOT A BAD DAY ON SATURDAY...ALBEIT A BIT CHILLY. HOWEVER...LOW PRESSURE OVER HUDSON BAY WILL SPARK SOME ISENTROPIC LIFT ALOFT ACROSS THE REGION...WITH LOTS OF HIGH CLOUDINESS BEING THE RESULT. TEMPS UNDER THE CLOUDINESS WILL BE COOL...AND HAVE UNDERCUT THE GUIDANCE BY A FEW DEGREES AS WE PROBABLY WONT SEE FULL MIXING. HIGHS WILL TOP OUT IN THE MID 30S. SATURDAY NIGHT...SKIES WILL CLEAR BACK OUT...BUT WITH GOOD WARM ADVECTION UNDERWAY...WILL SEE LOWS A GOOD 5-7F WARMER THAN THE NIGHT BEFORE...IN THE LOW TO MID 20S. SUNDAY LOOKS LIKE A NICE DAY AS THE WARM ADVECTION CONTINUES. UNDER MSUNNY SKIES...T925 AROUND THE FREEZING MARK SHOULD YIELD HIGHS IN THE LOW TO MID 40S. OUR NEXT WEATHER MAKER WILL TAKE SHAPE SUNDAY NIGHT WITH LOW PRESSURE DEVELOPING OVER THE SOUTHERN MISSISSIPPI VALLEY AND MOVES RAPIDLY NORTHEASTWARD. THE GFS AND NAM DIFFER BY ABOUT 6 HOURS ON PRECIP ARRIVAL WITH THE GFS BEING FASTER. THIS WILL END UP BEING PRETTY IMPORTANT BECAUSE IF THE PRECIP ARRIVES EARLY ENOUGH ON MONDAY...SURFACE TEMPS MAY BE COLD ENOUGH TO SUPPORT SOME FREEZING RAIN. THE MREFS ARE IN THE GFS CAMP WHILE THE SREFS ARE SLOWER AND MORE LIKE THE NAM. HAVE BROUGHT IN LIKELY POPS BY MONDAY AFTERNOON...BUT HAVE KEPT POPS IN THE CHANCE CATEGORY MONDAY MORNING. INCLUDED A SCHC OF ZR EARLY MONDAY IN THE GRIDS...BUT CONFIDENCE IN ANY SIGNIFICANT ICING IS QUITE LOW. ALL MODELS ARE IN AGREEMENT THAT THE LOW TRACK WILL BE WELL WEST OF THE CWA...SO BY MONDAY AFTERNOON...WILL HAVE NO MORE PTYPE ISSUES. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... STORM SYSTEM MOVES NORTHEAST OF THE AREA MONDAY NIGHT... WITH THE BULK OF THE RAIN ENDING BY TUESDAY MORNING. EXPECT A FEW LIGHT RAIN AND SNOW SHOWERS IN NORTHWEST FLOW BEHIND THE STORM WITH SOME LAKE ENHANCEMENT. AFTER A SHORT BREAK IN THE WEATHER ON WEDNESDAY... ANOTHER COLD FRONT CROSSES THE AREA ON THURSDAY ACCOMPANIED BY A FEW RAIN SHOWERS. MUCH COLDER AIR IS PROGGED TO ARRIVE THURSDAY NIGHT THROUGH FRIDAY WITH SCATTERED LAKE EFFECT SNOW SHOWERS AND TEMPERATURES FALLING BELOW NORMAL. WENT WITH GMOS FOR TEMPERATURES... AND MADE SOME MINOR TWEAKS TO GMOS POPS. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... SCT AREAS OF LINGERING MVFR CIGS AT ITH/RME/SYR WILL DISSIPATE OVER THE NEXT FEW HOURS AS HIGH PRESSURE BUILDS ACROSS THE AREA. EXPECT VFR CONDITIONS THROUGH THIS WEEKEND AS PATCHES OF HIGH CLOUD MOVE OVER THE AREA... BUT CIGS WILL REMAIN WELL ABOVE THE VFR THRESHOLD. OUTLOOK...BEST POTNL FOR MVFR TO IFR CIGS/VSBY/S WILL COME MON/MON NGT, AND AGAIN ON THU AS S/WV`S AND ASSCD FNTL SYSTEMS MOV THRU. POTNL FOR SOME LES IN THE WAKE OF BOTH SYSTEMS, PRIMARILY AFFECTING SYR/RME WITH POTNL FOR MVFR RESTRICTIONS. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...PVB NEAR TERM...PVB SHORT TERM...PVB LONG TERM...MSE AVIATION...MSE ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 1159 PM CST FRI NOV 23 2007 .AVIATION... DISCUSSION... PRECIPITATION IS ON THE INCREASE ACROSS SOUTHERN NEW MEXICO ACCORDING TO AREA RADARS...WHILE 11-3.9 SATELLITE IMAGERY SHOWS STRATUS CLOUDS EXPANDING/DEVELOPING ACROSS WEST TEXAS AND SOUTHEASTERN NEW MEXICO. WE CONTINUE TO EXPECT CIGS TO DROP BELOW MVFR ACROSS MOST TAF SITES AFTER 12Z...WITH INTERMITTENT IFR AND LIFR CONDITIONS IN SN/BR THROUGH TOMORROW AFTERNOON. && .PREV DISCUSSION... /ISSUED 933 PM CST FRI NOV 23 2007/ UPDATE... WATER VAPOR IMAGERY AND RUC H5 HEIGHT ANALYSIS INDICATE THAT INITIAL SHORTWAVE TROUGH IS NOW DIVING SOUTHWARD ACROSS SOUTHWESTERN COLORADO AND NORTHWESTERN NEW MEXICO...WHILE SECONDARY UPPER LEVEL LOW IS BEGINNING TO PINCH OFF ACROSS SOUTHWESTERN ARIZONA AND THE NORTHERN BAJA REGION AS EXPECTED COURTESY OF 90-100 KNOT UPPER JET DIVING SOUTHWARD ACROSS UTAH/NEVADA. SYNOPTIC SCALE LIFT IS BEGINNING TO INCREASE FROM SOUTHWESTERN TO CENTRAL NEW MEXICO AS EVIDENCED BY INCREASING PRECIPITATION RETURNS ON REGIONAL RADAR IMAGERY. THIS LIFT SHOULD BE INCREASING FROM THE GUADALUPE MOUNTAINS TO THE SOUTHEASTERN NEW MEXICO PLAINS AFTER 06Z...AND EXPECT SNOW TO INCREASE IN COVERAGE ACROSS THESE LOCATIONS DURING THIS TIME FRAME. HAVE DECIDED TO INCREASE OVERNIGHT POPS SIGNIFICANTLY TO THE LIKELY CATEGORY ACROSS THE ABOVE MENTIONED LOCATIONS...BETTER IN LINE WITH THE CURRENT WSW PRODUCT. ALSO INCREASED POPS GENERALLY ALONG AND NORTH OF THE I-20 CORRIDOR BEFORE 12Z. WE HAVE ALSO MADE SOME ADJUSTMENTS TO THE SATURDAY FORECAST. COLD FRONT SHOULD CONTINUE TO DIVE SOUTHWARD ACROSS THE CWA DURING THE DAY...AND LARGE SCALE LIFT SHOULD BECOME FOCUSED ACROSS THE CENTRAL AND SOUTHERN CWA AS THE DAY PROGRESSES AS THE UPPER LOW DEEPENS ACROSS NORTHERN MEXICO. AS SUCH...HAVE INCREASED POPS TO LIKELY CATEGORY ACROSS MOST LOCATIONS SATURDAY. FORECAST SOUNDINGS INITIALLY SUGGEST A MIX OF RAIN/SNOW SOUTH OF I-20 DURING THE MORNING...BUT DO SUPPORT ALL SNOW ACROSS VIRTUALLY THE ENTIRE CWA DURING THE AFTERNOON. WILL LET THE MID SHIFT DETERMINE IF A SNOW ADVISORY WILL BE NEEDED...INITIAL THOUGHTS ARE THAT ONE MAY BE NECESSARY FROM THE VAN HORN CORRIDOR TO THE PERMIAN BASIN TOMORROW. SNOW ACCUMULATIONS OF 3 TO 5 INCHES...WITH ISOLATED AMOUNTS OVER 6 INCHES LOOK PROBABLE ACROSS SOUTHEAST NEW MEXICO AND THE GUADALUPE MOUNTAINS BY TOMORROW EVENING IN THE WINTER STORM WARNING AREA. HIGH TEMPERATURES HAVE BEEN ADJUSTED DOWNWARD ACROSS A GOOD PORTION OF THE AREA. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT MST SATURDAY NIGHT FOR THE FOLLOWING ZONES...CENTRAL LEA COUNTY...EDDY COUNTY PLAINS...GUADALUPE MOUNTAINS OF EDDY COUNTY...NORTHERN LEA COUNTY...SOUTHERN LEA COUNTY. TX...WINTER STORM WATCH FROM 6 AM SATURDAY TO 12 PM CST SUNDAY FOR THE FOLLOWING ZONES...ANDREWS...BORDEN...CRANE... DAVIS/APACHE MOUNTAINS AREA...DAWSON...ECTOR...GAINES... GLASSCOCK...HOWARD...LOVING...MARTIN...MIDLAND...MITCHELL... PECOS...REAGAN...REEVES COUNTY AND UPPER TRANS PECOS... SCURRY...UPTON...VAN HORN AND HIGHWAY 54 CORRIDOR...WARD... WINKLER. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT MST SATURDAY NIGHT FOR THE FOLLOWING ZONES...GUADALUPE MOUNTAINS. && $$ 13 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 1155 PM CST FRI NOV 23 2007 .AVIATION... SNOW CONTINUES IN EARNEST ACROSS THE PANHANDLES ALTHOUGH CURRENT WSR-88D RADAR IMAGERY SHOWS THE SNOW DIMINISHING IN COVERAGE WEST OF TUCUMCARI. EXPECT MVFR CIGS AND VISBYS FOR THE MOST PART EXCEPT TRENDED TOWARD IFR CIGS AND VISBYS IN THE NEAR TERM TO ACCOUNT FOR THE LAST BAND TO MOVE ACROSS THE TERMINALS. EXPECT AREAS OF FOG TO DEVELOP BEFORE SUNRISE AS THE 00Z RAOB DATA INDICATES AMPLE BOUNDARY LAYER MOISTURE. FROPA SLATED TO PASS THROUGH THE PANHANDLES AROUND EARLY SAT MORNING. ALTHOUGH DRIER AIR IS EXPECTED TO MOVE INTO THE AREA...SKIES WILL BE SLOW TO CLEAR WITH CIGS LIFTING TO VFR BY AROUND 16-18Z. WINDS WILL REMAIN FAIRLY LIGHT OVERNIGHT AND WILL BECOME NORTHEAST ONCE THE FRONT PASSES THROUGH. WIND SPEEDS WILL GENERALLY REMAIN NEAR 10 KTS SAT AND DIMINISH TO LIGHT AND VARIABLE BY THE END OF THE FCST. CLK && .PREV DISCUSSION... /ISSUED 751 PM CST FRI NOV 23 2007/ UPDATE... ADDED BEAVER...OCHILTREE AND LIPSCOMB COUNTIES TO THE SNOW ADVISORY. CALLS UP TO BEAVER REVEAL THAT THERE IS 2 INCHES OF SNOW ON THE GROUND NOW. RADAR AND SATELLITE TRENDS SUGGEST THAT MORE SNOW IS HEADED TOWARD THIS AREA...THEREFORE THE SNOW ADVISORY. PREV DISCUSSION... /ISSUED 649 PM CST FRI NOV 23 2007/ UPDATE... WENT AHEAD AND EXTENDED THE SNOW ADVISORY UNTIL 6 AM SATURDAY FOR THE SAME AREA. SNOW ACROSS EASTERN NEW MEXICO IS EXPECTED TO CONTINUE SPREADING EAST ACROSS OUR AREA. LOW LEVEL UPSLOPE FLOW ALONG WITH THE ENTRANCE REGION OF THE JET STREAM MOVING OVER SHOULD ENHANCE SNOWFALL ACROSS THE ADVISORY AREA. 1 TO 3 INCH ADDITIONAL ACCUMULATIONS ARE EXPECTED WITH THE GREATEST AMOUNTS IN THE WESTERN OKLAHOMA AND NORTHWEST TEXAS PANHANDLE MAINLY NORTHWEST OF A LINE FROM GUYMON TO ADRIAN. PREV DISCUSSION... /ISSUED 616 PM CST FRI NOV 23 2007/ AVIATION... SNOW CONTINUES TO INCREASE IN COVERAGE ACROSS CENTRAL NEW MEXICO GENERATED BY A S/WV TROUGH NEAR THE FOUR CORNERS REGION. EXPECT THIS AREA OF SNOW TO BECOME MORE WIDESPREAD TONIGHT. THUS INSERTED PREVAILING LIGHT SNOW WITH MVFR CIGS AND VISBYS INITIALLY. APPEARS THE BEST FRONTOGENICAL LIFT WILL BE FOCUSED ACROSS THE NORTHERN TAF SITES WHERE CIGS CAN DETERIORATE TO IFR. DID ALSO MENTION IFR CIGS AT KAMA IN A TEMPO GROUP DUE TO A 90 KT JET STREAK THAT IS FORECAST TO MOVE ACROSS THE PANHANDLES. POINT FCST SOUNDINGS CONTINUE TO INDICATE A MOIST BOUNDARY LAYER AND COUPLED WITH LIGHT WINDS...AREAS OF FREEZING FOG ARE POSSIBLE. AFTER 12Z...EXPECT THE LIGHT SNOW TO GRADUALLY END AS THE S/WV PASSES TO THE EAST AND THE LIFT DIMINISHES. CONFIDENCE IN CONDITIONS IMPROVING RAPIDLY IS RATHER LOW...SO HELD ONTO MVFR CIGS FROM 13Z ON. CLK PREV DISCUSSION... /ISSUED 349 PM CST FRI NOV 23 2007/ DISCUSSION... SNOW ADVISORY WILL CONTINUE UNTIL 6 PM. RUC ANALYSIS SHOWS A FEW HOUR WINDOW WHERE ADDITIONAL SNOW FALL IS POSSIBLE IN THE ADVISORY AREA. WV IMAGERY STILL SHOWS A WEAK WAVE PUSHING THROUGH CENTRAL NEW MEXICO TOWARD THE PANHANDLES...WITH ABQ RADAR SHOWING A BAND OF SNOW MOVING EAST ALONG WITH THE SHORT WAVE. MODELS DIFFER ON WHEN TO END THE PRECIP OVER THE PANHANDLES...BUT THE GENERAL CONSENSUS IS FOR DRIER AIR TO PREVAIL AFTER 00Z. WOULD LIKE TO SEE HOW FAR EAST THE BAND OF SNOW OVER CENTRAL NEW MEXICO IS ABLE TO TRAVEL BEFORE BEING CONFIDENT IN EXTENDING THE SNOW ADVISORY. MODELS INDICATE THE ISENTROPIC LIFT WILL DIMINISH AFTER 00Z...WHILE THE COLD FRONT WILL BE NEARING THE OKLAHOMA PANHANDLE. FRONT MAY ACT AS A NEW SOURCE FOR LIFT...BUT AIRMASS IS DRIER BEHIND THE FRONT. SO WILL ALLOW THE CURRENT ADVISORY TO PLAY OUT UNTIL 00Z...AND WILL NOT EXTEND IN TIME FOR NOW. COULD STILL SEE LIGHT ACCUMULATIONS SO LEFT THE HIGH END CHANCE POPS IN PLACE THROUGH SATURDAY MORNING. OVERNIGHT LOWS WILL DEPEND ON CLOUD COVER AND SFC MOISTURE. APPEARS SKIES WILL REMAIN CLOUDY OVERNIGHT...WHILE DEW POINTS WILL GRADUALLY DECREASE WITH THE FRONTAL PASSAGE. FRONT SHOULD MOVE INTO NORTHWEST PANHANDLES BY 12Z...WITH DEW POINTS FALLING INTO THE UPPER TEENS. SO LIKEWISE KEPT THE LOWEST TEMPS ACROSS THE NW. INSERTED MENTION OF PATCHY FOG IN THE GRIDS THROUGH THE MORNING HOURS. SURFACE OBS HAVE PERIODICALLY REPORTED FOG AND THINKING THE AIRMASS WILL NEAR SATURATION AS OVERNIGHT TEMPS DECREASE. NOT CONFIDENT ON DENSE FOG HOWEVER. THE FRONT SHOULD THEN MOVE THROUGH THE PANHANDLES BY 18Z SATURDAY. DIFFICULT TO SAMPLE THE POST FRONTAL AIRMASS WITH THE SNOW AND CLOUD CONTAMINATION TAKING PLACE TO THE NORTH AND WEST...BUT THINKING CLOUD COVER WILL DECREASE SOME WHAT TOMORROW AND WIND SPEEDS SHOULD ONLY MAX OUT AT 10 TO 15KT. SO HIGH TEMPS SHOULD BE SIMILAR IF NOT A DEGREE OR TWO WARMER TOMORROW. THERE IS ALSO SOME POTENTIAL FOR SNOW TO LINGER ACROSS THE EXTREME SOUTHERN CWA INTO THE EARLY AFTERNOON HOURS TOMORROW. MODELS STILL A BIT UNSURE ON THE SOUTHERLY PROGRESSION OF THE MAIN UPPER LOW...BUT THE GFS AND NAM DO HINT AT LIGHT SNOW FOR A FEW HOURS AFTER 18Z. INSERTED A THIN ROW OF SLIGHT CHANCE POPS ALONG THE SOUTHER TEXAS PANHANDLE. AFTER THAT...THE MODELS DIVERGE SLIGHTLY ON THE TRACK OF THE LOW. WITH THE 12Z RUNS...THE NAM IS THE OUTLIER SHOWING THE FURTHEST NORTH AND WESTERN TRACK. IN ADDITION...THE NAM PAINTS SOME WRAP AROUND PRECIP INTO THE EASTERN PANHANDLES THROUGH SUNDAY. WHILE THE GFS/EURO/AND UKMET PULL THE LOW MORE TO THE SOUTH AND EAST. SO...DECIDED TO INSERT NON MENTIONABLE POPS ACROSS THE EAST BUT DID NOT BITE OFF ON THE NAM. A WARMING TREND COULD THEN BE IN THE WORKS FOR MONDAY AND TUESDAY...IF MID 50S ARE CONSIDERED WARM. NONETHELESS...WITH THE UPPER LOW PUSHING NORTHEAST...AND THE COLD FRONT WELL SOUTH OF THE PANHANDLES...SOUTHERLY SFC FLOW WILL ADVECT SLIGHTLY WARMER TEMPS INTO THE AREA FOR MONDAY. ESPECIALLY IF SKIES CLEAR OUT. UPPER FLOW BECOMES MORE SOUTHWESTERLY ON TUESDAY AND A LEE TROUGH DEVELOPED PROVIDING SOUTHWEST SFC FLOW. MEX WAS SUGGESTING HIGHS NEAR 60. FELT THAT MIGHT BE A TAD OPTIMISTIC SO WENT WITH MID 50S AREA WIDE. A STRONGER FRONT IS THEN PROGGED TO REACH THE SOUTHERN PLAINS WEDNESDAY AS A DEEPENING UPPER TROUGH DIGS SOUTH ALONG THE ROCKIES. MODELS SHOWING THE FRONT TO BE DRY...SO BIGGEST ISSUE WILL BE THE STRENGTH OF THE COLD AIR. APPEAR THE TROUGH WILL DRIVE SOUTH OUT OF THE GULF OF ALASKA. SO AT THIS POINT...DECIDED TO TREND WITH THE MEX AS IT HAD REASONABLE HIGH TEMPS FOR THE THURSDAY FRIDAY TIME FRAME. LAST MAJOR CHANGE WAS TO REMOVE THE POPS FROM THURSDAY. MODELS ARE COMING IN DRY WITH THE LATEST RUNS...AND SEEM TO BE PUSHING THE CHANCES FOR PRECIP BACK WITH EACH RUN. SO INSERTED SOME 10 POPS FOR THE DAY 7 AND 8 TIME FRAME...AND WILL WAIT TO SEE WHAT THE NEXT RUN HAS IN STORE. JJB && AMA WATCHES/WARNINGS/ADVISORIES... TX...SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...DALLAM...DEAF SMITH...HANSFORD... HARTLEY...HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE... OLDHAM...POTTER...RANDALL...SHERMAN. OK...SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. $$ 05/15 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 932 AM EST SAT NOV 24 2007 .DISCUSSION...12 UTC SURFACE ANALYSIS SHOWS A 1034MB HIGH CENTERED NEAR ROANOKE VA WITH A SURFACE RIDGE AXIS RUNNING FROM WESTERN NEW ENGLAND DOWN INTO UPSTATE SOUTH CAROLINA. VERY TIGHT DEWPOINT GRADIENT IS NOTED JUST OFFSHORE OF THE NORTH FLORIDA COAST...BUT THE ACTUAL SURFACE FRONT IS ANALYZED MUCH FURTHER SOUTH...GENERALLY ABOUT 25N...WHERE THE SURFACE WINDS BEGIN TO PICK UP A SLIGHT SOUTHERLY COMPONENT. THIS ALSO MATCHES UP WELL WITH THE ONGOING CONVECTIVE ACTIVITY SOUTHWEST OF BROWNSVILLE IN THE WESTERN GULF OF MEXICO. THE 500 MB PATTERN AT 12 UTC ACROSS THE COUNTRY IS DOMINATED BY A LARGE POSITIVELY TILTED TROF WHOSE AXIS EXTENDS FROM A NEAR CUT OFF LOW NEAR TUCSON NORTHEASTWARD TOWARD LAKE SUPERIOR. COMPUTER MODELS INDICATE THE NORTHERN PORTION OF THIS TROF WILL DEPHASE WITH THE SOUTHERN END LATER TODAY...WITH THE SOUTHERN END BECOMING A CLOSED OFF LOW OVER THE SOUTHWEST. INTERESTING SET UP FOR THE NEXT COUPLE OF DAYS...WITH QUITE A BIT OF WEATHER TO DISCUSS. WITH THE MORE RAPIDLY MOVING NORTHERN STREAM...OUR WEATHER WILL BE DERIVED FROM THE SLIGHTLY SLOWER SOUTHERN STREAM. AS THE TROF DEPHASES AND THE SOUTHERN END CUTS OFF OVER THE DESERT SOUTHWEST...THE SURFACE WARM FRONT OVER THE SOUTHERN GULF OF MEXICO WILL BEGIN TO LIFT NORTHWARD. THE MOVEMENT OF THIS FRONT WILL BE SLOW AND STEADY TODAY...WITH OVERRUNNING MOISTURE ALREADY BEGINNING TO ARRIVE. THE PRECIPITABLE WATER ON THE 12 UTC SOUNDING AT KTAE WAS ONLY UP 0.08 INCHES (TO 0.79 INCHES) FROM THE LAUNCH JUST 12 HOURS AGO. HOWEVER...WE ARE ALREADY SEEING UPPER LEVEL CLOUDINESS SPREADING NORTHEASTWARD OFF THE CONVECTION IN THE SOUTHWEST GULF. EXPECT TO SEE MOISTURE LEVELS...MAINLY IN THE MID AND UPPER LEVELS...RISE THROUGH THE DAY. THOUGH ISENTROPIC LIFTING WILL BE ONGOING FROM MID AFTERNOON...MUCH OF THE MOIST LIFTING WILL INITIALLY BE ELEVATED (305 K SURFACE AND HIGHER). THE 300K AND 295K ANALYSES SHOW PARCELS NEEDING TO BE LIFTED 150MB TO 200MB FROM THEIR INITIAL POSITIONS TO BECOME SATURATED THROUGH MIDDAY. GIVEN THIS...AND THE ONLY GRADUAL MOISTENING OF THE SURFACE LAYER...WILL LEAVE POPS OUT OF THE OFFICIAL FORECAST THROUGH 00Z AS CURRENTLY INDICATED. WITH CONTINUED NORTHEASTERLY FLOW AT THE SURFACE...AND ARRIVING CLOUD COVER...TEMPERATURES WILL ONLY BE A FEW DEGREES WARMER THAN YESTERDAY. CURRENT ZONE FORECAST HAS PARTLY CLOUDY ACROSS THE BOARD. GIVEN THAT THE FIRST BATCH OF HIGHER CLOUD COVER IS LARGELY TRANSPARENT (BASED ON EARLY VISIBLE IMAGERY)...WILL NOT MAKE ANY ADJUSTMENTS AT THIS TIME. THE REST OF THE FORECAST IS IN GOOD SHAPE AND WILL ONLY UPDATE THE GRIDS THIS MORNING TO REFLECT CURRENT OBSERVATIONS. HAVE A GREAT DAY! && .AVIATION...VFR CONDITIONS ARE CURRENTLY BEING REPORTED AT ALL TERMINALS. CEILINGS WILL LOWER FROM SOUTH TO NORTH FROM 25K FT THIS MORNING...TO MVFR LEVELS (2-3K FT) LATER TODAY...AND POSSIBLY TO IFR/LIFR LATE TONIGHT. JUST HOW QUICKLY THIS OCCURS WILL BE TRICKY. THE NAM/WRF/RUC HOLD OFF THE BEST ISENTROPIC LIFT (AND LOWER CIGS) UNTIL THIS EVENING WHILE THE GFS (AND MOS) BRING IT IN THIS AFTERNOON. THERE MAY HAVE BEEN SOME LOW LEVEL WIND SHEAR JUST BEFORE SUNRISE AT SOME OF THE TERMINALS...BUT THE STABLE BOUNDARY LAYER IS RAPIDLY MIXING OUT SO LLWS IS NO LONGER EXPECTED. && .MARINE...WINDS AND SEAS OVER THE WATERS ARE AT SCEC CRITERIA AND DON`T EXPECT THEM TO LOWER ANY TIME SOON. WILL MONITOR FOR SCA CONDITIONS...BUT BASED ON THE CURRENT AND FUTURE PRESSURE GRADIENT...DON`T EXPECT SCA CONDITIONS TODAY. MAY HAVE TO UPGRADE THE WESTERN WATERS TO AN ADVISORY FOR TONIGHT...BUT WILL CONTINUE TO MONITOR THIS DEVELOPING STORM SYSTEM CLOSELY. && .FIRE WEATHER...INCREASING MOISTURE LEVELS (AND HIGHER DEWPOINTS) TODAY WILL OFFSET THE SLIGHTLY WARMER TEMPERATURES AND KEEP RELATIVE HUMIDITY VALUES FROM APPROACHING CRITICAL LEVELS TODAY. && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE && $$ AVIATION...FOURNIER REST OF DISCUSSION...GODSEY fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1038 AM EST SAT NOV 24 2007 .UPDATE...12Z SURFACE/RUC ANALYSIS AND VIS/IR/WV/RADAR ANALYSIS SHOW NORTHERN MICHIGAN LYING BETWEEN SURFACE HIGH PRESSURE OVER THE MID-ATLANTIC STATES AND LOW PRESSURE OVER NORTHERN ONTARIO. WEAK MID-LEVEL WAVE IS CUTTING ACROSS THE UPPER MIDWEST THIS MORNING AND MID-UPPER LEVEL MOISTURE IS SPREADING ACROSS WESTERN WISCONSIN/SOUTHERN U.P./AND LOWER MICHIGAN IN A POCKET OF WEAK -DIVQ. 12Z APX SOUNDING SHOWS A MOIST PROFILE ABOVE 700MB WITH SUBTLE WARMING IN THE LOW LEVELS IN A WAA REGIME THAT HAS HELPED 850MB TEMPS WARM TO -9C. UPSTREAM 12Z GRB SOUNDING SHOWS A SIMILAR TALE WITH SLIGHTLY WARMER 850MB TEMPS AROUND -7C AND A MOIST PROFILE ABOVE 900MB. THIS MOISTURE COMBINED WITH DELTA T/S AROUND 17C AND INVERSION HEIGHTS AROUND 6KFT HAS ALLOWED SW BAND OF LES TO CONTINUE RIGHT ALONG THE LAKE MICHIGAN SHORELINE FROM NORTHPORT TO PELLSTON WITH A SLIGHT UPTICK IN INTENSITY OVER THE PAST HOUR. MEANWHILE...WITH THE TIGHT GRADIENT IN PLACE...WIND GUSTS AT THE NORTHERN LAKE MICHIGAN BUOY HAVE BEEN SLOWING INCREASING INTO THE UPPER 20S THIS MORNING. MAIN FORECAST CONCERNS CONTINUE TO REVOLVE AROUND LAKE EFFECT AND MARINE HEADLINES. NO MAJOR CHANGES PLANNED TO THE CURRENT FORECAST IN RESPECT TO HEADLINES. MID-LEVEL SHORTWAVE WILL MOVE EAST OVER THE REST OF THE DAY WITH 850-700MB RH REMAINING ABOVE 90 PCT AHEAD OF IT WHILE INVERSION HEIGHTS INCREASE TO AROUND 8-9KFT WITH THE WAVE PASSAGE JUDGING BY UPSTREAM ACARS DATA OVER CENTRAL WISCONSIN. DELTA T`S MAY TAKE A SLIGHT HIT TODAY BY A DEGREE OR SO WHICH WOULD PLACE 850MB TEMPS AROUND -7 TO -8C AND DELTA T`S APPROX. 16-17C. THESE PARAMETERS SUGGEST THAT LES ACTIVITY WILL REMAIN ABOUT STATUS QUO THROUGH THE AFTERNOON WITH 1000-850MB WINDS REMAINING ABOUT 240 DEGREES...WHICH WOULD TARGET CHARLEVOIX...EMMET...CHEBOYGAN...AND SOUTHERN MACKINAC COUNTIES. THERE IS STILL SOME CONCERN THAT WARMING TEMPS THIS AFTERNOON COULD LIMIT ACCUMULATIONS SOMEWHAT...ESPECIALLY RIGHT ALONG THE LAKESHORE. SURFACE TEMPS AT AT HARBOR SPRINGS IS AT 34 DEGREES AT 9 AM WHILE LOCAL GUIDANCE SUGGESTS PRECIP TYPE WITH 850MB TEMPS AROUND -8C AND LAKE TEMP AT 9C RIGHT AROUND THE SNOW/MIX LINE. HOWEVER...BELIEVE THIS WILL BE OFFSET BY THE RECENT SNOW PACK AND DYNAMIC COOLING OF THE BL WHICH WILL ALLOW SURFACE TEMPS TO REMAIN STEADY AND SNOWFALL TO ACCUMULATE. CURRENT GRIDS HAVE 3-5 INCHES THIS AFTERNOON FROM CHARLEVOIX TO EMMET TO MACKINAC COUNTIES...AND THIS CONTINUES TO LOOK GOOD. WILL HAVE TO KEEP AN EYE ON NW CHARLEVOIX COUNTY FOR POTENTIAL HEADLINE UPGRADE IF THE CURRENT BAND DOES NOT MOVE TOO MUCH. WHERE THERE IS LITTLE TO NO SNOW PACK FROM MANISTEE UP TO LEELANAU COUNTIES...HAVE PLACE A MIX ALONG THE LAKE SHORES IN FOR THE AFTERNOON AS SURFACE TEMPS ARE IN THE 34-36F RANGE. MARINE...WINDS IN THE MIXED LAYER WILL CONTINUE TO INCREASE THIS AFTERNOON INTO THE 35-45 KT RANGE WHICH WILL LAST THROUGH TONIGHT. WITH THE CURRENT UNSTABLE CONDITIONS OVER THE LAKE...BELIEVE GALE FORCE GUST WILL BE ACHIEVED LATER TODAY INTO TONIGHT. GALES MAY VERY WELL CONTINUE INTO TOMORROW AS WELL...BUT WILL MAKE THOSE DECISIONS IN THE 4PM ISSUANCE. ZONES OUT SHORTLY. MPC && .PREV DISCUSSION... /ISSUED 623 AM EST SAT NOV 24 2007/ AVIATION...PERSISTENT LOW LEVEL SW FLOW COUPLED WITH A SHORT WAVE AND SURFACE RESPONSE MOVING THRU NRN MICHIGAN WILL PRODUCE LAKE ENHANCED SNOW SHOWERS OVER THE NEXT 24 HOURS. THE HEAVIEST AND MOST PERSISTENT SNOWFALL WILL TARGET THE STRAITS AREA AND THE FAR NORTHWEST LOWER MICHIGAN SHORELINE (KPLN). IFR AND AT TIMES LIFR CONDITIONS CAN BE EXPECTED AT KPLN THROUGHOUT THE DAY...WITH PERIODIC HEAVY SNOW SHOWERS EXPECTED. THE REST OF NRN LOWER MICHIGAN (KAPN AND KTVC) WILL RECEIVE SCT/NMRS SNOW SHOWERS...WITH MAINLY VFR AND MVFR CONDITIONS EXPECTED. DRIER AIR AND BUILDING SUBSIDENCE WILL GRADUALLY ERODE SNOW SHOWER ACTIVITY ACROSS NRN MICHIGAN TONIGHT...WITH MAINLY MVFR CONDITIONS EXPECTED AT KPLN AND VFR CONDITIONS EXPECTED AT KAPN AND KTVC. && DISCUSSION...ISSUED 346 AM EST SAT SW FLOW LAKE EFFECT EVENT CONTINUES EARLY THIS MORNING. WIDESPREAD SNOW SHOWERS CONTINUE TO IMPACT THE STRAITS AREA...BUT HAS SHOWS A DOWNWARD TREND IN BOTH AREAL COVERAGE AND INTENSITY AS A QUICK SHOT OF DRIER AIR SWEEPS THRU THE REGION. DOWNWARD TREND WILL BE SHORT-LIVED AS DEEP MOISTURE AND SYNOPTIC LIFT APPROACHES OUR CWA THIS MORNING AHEAD OF A SHORT WAVE AND WEAK SURFACE RESPONSE. IMPACT THAT THIS SYSTEM WILL HAVE ON THE ONGOING SW FLOW LAKE EFFECT EVENT WILL BE THE MAIN FORECAST FOCUS FOR THE NEXT 24 HOURS...SPECIFICALLY REGARDING POPS AND ADDITIONAL SNOW ACCUMULATIONS. LAST HALF OF THE WEEKEND WILL FEATURE A BREAK IN THE ACTION AS DRIER AND WARMER AIR MOVES INTO THE REGION. TODAY AND TONIGHT...DEEP MOISTURE WILL SPREAD EASTWARD INTO OUR CWA THIS MORNING...AND REMAIN IN PLACE THRU THE AFTERNOON. LAST COUPLE OF IMAGES FROM KAPX 88D INDICATES THE INITIAL STAGES OF MID LEVEL MOISTENING ACROSS NW PORTIONS OF OUR CWA. ENHANCED MID LEVEL MOISTURE EXTENDS ALL THE WAY BACK THRU WRN UPPER MICHIGAN AND MUCH OF WISCONSIN PER UPSTREAM RADARS AND IR SATELLITE IMAGES. SW FLOW LAKE EFFECT EVENT IS QUICKLY BECOMING ENHANCED BY INCREASING SYNOPTIC MOISTURE AND LIFT VIA THE APPROACHING SHORT WAVE. DELTA T`S REMAIN IN THE MID TO UPPER TEENS THRU THIS EVENING. 1000-500 MB RH INCREASES TO AROUND 95 PCT BY 18Z TODAY...AS INVERSION HEIGHTS CLIMB TO AROUND 10 KFT. MAX 700-500 MB DIV-Q WILL BE SLIGHTLY DELAYED TOWARD EVENING...AT WHICH TIME RH WILL BE DECREASING AND LOW LEVEL WAA WILL BEGIN TO ERODE OVER-LAKE INSTABILITY. NEVERTHELESS...EXPECT THE STRAITS AREA AND FAR NW LAKE MICHIGAN SHORELINE AREAS WILL SEE AN ADDITIONAL 3 TO 5 INCHES OF SNOW TODAY...WITH THE HEAVIEST AND MOST PERSISTENT SNOW FALLING ACROSS EMMET...CHEBOYGAN AND MACKINAC COUNTIES. WILL MAINTAIN ONGOING HEADLINES FOR THESE COUNTIES. WILL ALSO ISSUE AN ADVISORY FOR CHARLEVOIX COUNTY FOR TODAY AS WRN PORTIONS OF THE COUNTY COULD SEE UP TO 4 INCHES OF NEW SNOW. HAVE REWORKED GRIDS FOR TODAY TO INCREASE POPS AND EXPECTED SNOW AMOUNTS. WILL NEED TO KEEP AN EYE ON PRECIP TYPE THROUGHOUT THE DAY AND EVEN INTO THIS EVENING AS MODEL SOUNDINGS SHOW SURFACE-BASED WARM LAYER WILL TRY TO DEEPEN TO NEAR 2 KFT BY EVENING. HOWEVER...THINK DYNAMIC COOLER AND POTENTIAL FOR HEAVIER PRECIP MAY OFFSET ANY LOW LEVEL WAA ENOUGH TO KEEP PRECIP OF THE FROZEN VARIETY. DRY AIR...SUBSIDENCE... FALLING INVERSION HEIGHTS AND LOW LEVEL WAA/DIMINISHING OVER-LAKE INSTABILITY WILL LIMIT POPS TO CHANCE FOR TONIGHT FOR W/SW FLOW AREAS...WITH ADDITIONAL SNOW ACCUMULATION REMAINING AOB AN INCH. FOR MARINE INTERESTS...WILL MAINTAIN GALE WARNINGS FOR ALL NEARSHORE ZONES AS STRENGTHENING SW FLOW WILL LIKELY PRODUCE GUSTS TO 35 TO 40 KTS. SUNDAY AND SUNDAY NIGHT...SURFACE RIDGING...DRY AIR AND LOW LEVEL WAA WILL BRING AN END TO ALL REMAINING LAKE EFFECT PRECIP BY 12Z SUNDAY. DRY CONDITIONS WILL CONTINUE THRU SUNDAY NIGHT...WITH PARTIAL CLEARING EXPECTED. HIGH TEMPS SUNDAY AFTERNOON WILL WARM NICELY INTO THE UPPER 30S AND LOWER 40S COURTESY OF ONGOING WAA. LOW TEMPS SUNDAY NIGHT WILL COOL BACK INTO THE UPPER 20S AND LOWER 30S. MONDAY THROUGH WEDNESDAY...PAR FOR THE COURSE WHEN YOU HAVE SUCH ENERGETIC NORTHERN STREAM FLOW...WITH POSSIBLE INTERACTION WITH NORTHEAST EJECTING SOUTHERN STREAM WAVE...A CHALLENGING AND QUESTION RIDDLED FORECAST. EARLY MORNING NORTHERN HEMISPHERIC WATER VAPOR IMAGERY SHOWS PRIMARY PLAYERS OF INTEREST...ESPECIALLY EARLY ON IN THE EXTENDED...AS A SHARP NORTHERN STREAM WAVE DIVING SOUTH OVER THE NUNAVUT REGION OF CANADA AND DEVELOPING MID LEVEL LOW PRESSURE JUST SOUTH OF THE ARIZONA/MEXICO BORDER. 00Z MODEL SUITE IN DECENT AGREEMENT SHOWING SOUTHERN SYSTEM MOVING NORTHEAST INTO THE LOWER MISSISSIPPI VALLEY BY MONDAY MORNING AS AFOREMENTIONED NORTHERN STREAM WAVE DIVES INTO SOUTH CENTRAL CANADA. MODELS ALSO SHOW ENOUGH TEMPORAL AND SPATIAL SEPARATION OF THESE SYSTEMS TO PREVENT PHASING UNTIL WELL EAST OF THE REGION...THUS FAVORING A FARTHER SOUTH TRAJECTORY OF THE SOUTHERN LOW UP THROUGH THE OHIO VALLEY ON MONDAY. THIS FAVORS CURRENT CHANCE POPS IN FAR SOUTHERN ZONES MONDAY AFTERNOON. CONFIDENCE QUICKLY GOES DOWNHILL BEYOND MONDAY... ESPECIALLY WITH AMPLITUDE OF NORTHERN WAVE...AND ASSOCIATED SURFACE FEATURES...AS IT CUTS ACROSS THE NORTHERN LAKES. LATEST ECMWF A LITTLE MORE AMBITIOUS IN THIS REGARD THAN OTHER GUIDANCE...SHOWING LOW PRESSURE DEVELOPING ALONG THE ARCTIC FRONT OVER WESTERN LAKE SUPERIOR MONDAY NIGHT WHICH GRADUALLY FILLS AS IT PIVOT SOUTHEAST. PROGRESSIVE PATTERN CONTINUES INTO THE MIDDLE OF THE WEEK WITH INTERMOUNTAIN TROUGH AMPLIFICATION LEADING TO SURFACE CYCLOGENESIS OVER THE HIGH PLAINS ON WEDNESDAY...WITH ITS SIGHTS SET ON THE NORTHERN LAKES FOR THURSDAY. EXACT TIMING...STRENGTH... AND PLACEMENT YET TO BE DETERMINED SO WILL MAINTAIN OVERALL FORECAST CONTINUITY...WITH THE EXCEPTION OF ADDING WELL AGREED UPON WAA LIGHT SNOW CHANCES OVER NORTHERN AREAS WEDNESDAY. MSB && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ015- 017-019. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ016. LM...GALE WARNING UNTIL 11 AM EST SUNDAY FOR LMZ323-341-342-344>346. LH...GALE WARNING UNTIL 11 AM EST SUNDAY FOR LHZ345>349. LS...GALE WARNING UNTIL 5 AM EST SUNDAY FOR LSZ321-322. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 647 AM EST SAT NOV 24 2007 UPDATED AVIATION SECTION FOR 12Z TAF ISSUANCE .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR SNOW TODAY. WATER VAPOR IMAGERY AND RUC SHOWING A DEEP LOW OVER CENTRAL CANADA WITH AN ACCOMPANYING LONGWAVE TROUGH STRETCHING ACROSS CENTRAL CONUS TO A LOW OVER SOUTHWEST NEW MEXICO. A STEEP RIDGE IS OVER THE PACIFIC NORTHWEST AND THE CANADIAN ROCKIES. ANOTHER TROUGH IS OVER EASTERN CANADA. WEAK SHORTWAVES MIGRATING THROUGH THE TROUGH ARE OVER EAST CENTRAL WISCONSIN AND NORTHERN LOWER MICHIGAN. OTHER SHORTWAVES ARE OVER NORTHERN MANITOBA AND WESTERN SASKATCHEWAN. SURFACE ANALYSIS DEPICTS A LARGE HIGH OVER EAST CENTRAL ATLANTIC STATES WITH A RIDGE STRETCHING WEST ACROSS THE OHIO RIVER VALLEY INTO THE MIDDLE MISSISSIPPI RIVER VALLEY. A DEEP LOW IS OVER WESTERN HUDSON BAY WITH A FRONTAL SYSTEM EXTENDING ACROSS CENTRAL MANITOBA AND CENTRAL SASKATCHEWAN. A WEAK TROUGH WHICH IS A REFLECTION OF THE LONGWAVE TROUGH IS LOCATED OVER MINNESOTA...NORTHWEST IOWA AND EASTERN NEBRASKA. THE LONGWAVE TROUGH WILL SWEEP ACROSS THE FORECAST AREA TODAY AS WILL THE SURFACE REFLECTION. AN 850MB THERMAL TROUGH OVER WESTERN ONTARIO WILL WEAKEN AS IT MOVES INTO LAKE SUPERIOR THIS AFTERNOON. HOWEVER...THE LAKE-850MB DELTA-T WILL STILL BE LARGE ENOUGH TO CAUSE LAKE EFFECT SNOWS. 280K ISENTROPIC ASCENT ACCOMPANYING THE SURFACE TROUGH MOVING THROUGH THE AREA WILL SUPPORT BRING SOME SNOW TO THE AREA. FORECAST SOUNDINGS SHOWING THAT IT WILL BE FAIRLY DRY ABOVE 850MB AND LOW LEVEL MOISTURE WILL BE LIMITED MAINLY TO WHAT COMES FROM THE LAKE. SURFACE WINDS ARE EXPECTED TO BE MAINLY OUT OF THE SOUTHWEST SO MOST OF THE LES WILL OCCUR ON THE CANADIAN SIDE OF LAKE SUPERIOR AND EAST OF THE FORECAST AREA. THE 280K ISENTROPIC WINDS WILL BE A LITTLE MORE WESTERLY THUS THE KEWEENAW PENINSULA COULD STILL GET SOME LAKE EFFECT SNOWS. THE REST OF THE AREA SHOULD ONLY RECEIVE LIGHT AMOUNTS DUE TO THE DRY CONDITIONS. A 40 KNOTS LOW LEVEL JET WILL SHIFT ACROSS THE AREA TODAY. THE STEEP LAPSE RATE OVER LAKE SUPERIOR SUPPORTS MIXING THE WINDS TO SURFACE...WHICH WILL REACH GALE FORCE OVER LAKE SUPERIOR. THE LONGWAVE TROUGH WILL SHIFT TO NORTHERN NEW ENGLAND TONIGHT SETTING UP MORE OF A ZONAL FLOW ACROSS NORTHERN CONUS. MID LEVEL INSTABILITY WILL SHIFT EAST AS WELL. A SHORTWAVE WILL SAIL ACROSS WESTERN CONUS IN THE ZONAL FLOW AND REACH NORTH DAKOTA AND NORTHEAST MONTANA. WARM AIR ADVECTION WILL PUSH THE 850MB THERMAL TROUGH INTO NORTHERN ONTARIO. THE CANADIAN COLD FRONT WILL SETTLE OVER LAKE SUPERIOR AND NORTHERN MINNESOTA TONIGHT. ISENTROPIC ASCENT ACCOMPANYING THIS FRONT COULD GENERATE A MORE SNOW SHOWERS NORTH OF THE FRONT. THE CRITICAL FACTOR HERE WILL THE PLACEMENT OF THE FRONT. THE LOCALLY GENERATE HIGH RESOLUTION WRF CONTINUES TO PLACE THE FRONTAL SYSTEM AND MOISTURE FIELD OVER LAKE SUPERIOR AND THE KEWEENAW PENINSULA. THE REGIONAL CANADIAN IS SUPPORTING THIS SCENARIO AS WELL WHILE THE NAM ALSO SUPPORTS THE FRONTAL POSITION BUT IS A LITTLE DRIER. THUS WILL KEEP THE FORECAST AREA DRY EXCEPT FOR THE KEWEENAW PENINSULA AND CENTRAL AND EASTERN LAKE SUPERIOR TONIGHT. THE LOW LEVEL JET WILL REMAIN OVER LAKE SUPERIOR BUT WILL WEAKEN TO 30 KNOTS OVERNIGHT. A WEAK SHORTWAVE WILL RACE ACROSS LAKE SUPERIOR AND WESTERN PART OF THE FORECAST AREA ON SUNDAY. THE SURFACE LOW AND FRONTAL SYSTEM WILL MOVE TO NORTH CENTRAL LAKE SUPERIOR. MODELS CONTINUE TO SHOW THAT THE BEST CHANCE OF PRECIPITATION WILL BE NORTH OF THE FRONTAL SYSTEM. LAKE SUPERIOR AND THE KEWEENAW PENINSULA WILL CONTINUE TO HAVE SNOW SHOWERS IN THE MORNING. THE NORTHERN PART OF LAKE SUPERIOR WILL HAVE SNOW SHOWERS LATE IN THE AFTERNOON AS PER NAM/GFS/GEM. ONE BRANCH OF THE LOW JET WILL BE OVER WESTERN ONTARIO WHILE THE OTHER IS OVER THE NORTHERN MISSISSIPPI RIVER VALLEY. WINDS OVER THE LAKE WILL BE FAIRLY LIGHT. THE SHORTWAVE WILL RACE ACROSS LAKE SUPERIOR SUNDAY NIGHT...WHILE THE SURFACE LOW RELOCATES OVER EAST CENTRAL ONTARIO. THE FRONT WILL CONTINUE TO BE DRAPED ACROSS THE NORTHERN U.P. AND LAKE SUPERIOR. A HIGH PRESSURE RIDGE WILL PUSH INTO SOUTH CENTRAL CANADA. ANTI CYCLONIC FLOW AHEAD OF THE HIGH WILL DRAW COOLER AIR INTO THE FORECAST AREA FROM CENTRAL CANADA. THE WINDS WILL BE OUT OF THE NORTHWEST OVER THE LAKE AND THE 850MB DELTA-T WILL BE AROUND 14C. FORECAST SOUNDINGS FAVORABLE FOR LAKE EFFECT SNOW OVER THE FORECAST BY SUNRISE. GEM/GFS/ECMWF WILL BRING THE COOLER AIR INTO THE FORECAST AREA ABOUT 6 HOURS EARLIER THAN PREVIOUS SHOWN FOR MONDAY. THUS WILL MOVE UP THE CHANCES OF LAKE EFFECT SNOW BY 6 HOURS. THE WIND DIRECTIONS WILL SHOW WHERE THE FAVORED AREAS OF HEAVIEST LAKE EFFECT SNOWFALL WILL OCCUR. A MID LEVEL LOW WILL SWING OUT OF CENTRAL CANADA ACROSS ONTARIO MONDAY NIGHT INTO WEST CENTRAL QUEBEC ON TUESDAY. THE COOLEST AREA (-22C) OF THE 850MB THERMAL TROUGH WILL TRACK ACROSS ONTARIO LATE MONDAY NIGHT AND TUESDAY. LOW LEVEL MOISTURE IS EXPECTED TO INCREASE. WINDS WILL FAVOR SOME LES. HOWEVER...INSTABILITY WITH THE SHORTWAVE AND SURFACE LOW...AND AVAILABLE MOISTURE WILL GENERATE A FEW SHOWERS WHICH WILL BE ENHANCED WITH THE LAKE EFFECT SNOWS DUE TO THE THERMAL TROUGH MOVING THE ONTARIO. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... AREA OF LIGHT SNOW AND FLURRIES ENCOMPASSING MUCH OF NORTHERN WI INTO UPPER MI IS EXPECTED TO MOVE EAST THROUGH EARLY THIS AFTERNOON. BOTH TAF SITES HAVE EXPERIENCED PERIODS OF VISIBILITIES DROPPING TO MVFR (OR LESS IN THE CASE OF CMX) AND CEILINGS OF MVFR. THIS SHOULD CONTINUE AT BOTH SITES UNTIL THE AREA OF LIGHT SNOW PUSHES EAST. THE NEXT CONCERN IS THE POSSIBILITY OF A LAKE EFFECT BAND OVER WESTERN LAKE SUPERIOR MOVING INTO CMX THIS AFTERNOON AND ANOTHER TONIGHT. ONE SHIP ON WESTERN LAKE SUPERIOR AT 5 AM EST REPORTED 1/8SM VISIBILITY ALONG A SURFACE TROUGH WHERE A LAKE EFFECT BAND WOULD BE EXPECTED. WINDS TURNING WESTERLY SHOULD BRING THE TROUGH AND BAND INTO THE KEWEENAW EARLY THIS AFTERNOON...BUT WITH CONVERGENCE PROGGED TO WEAKEN ALONG THE TROUGH...THE BAND MAY NOT BE AS STRONG. THUS ONLY INDICATED VISIBILITIES AS LOW AS 3SM. ANOTHER COLD FRONT DROPPING SOUTH INTO LAKE SUPERIOR TONIGHT SHOULD HELP TO GENERATE ANOTHER WEST TO EAST LAKE EFFECT BAND. THIS BAND...IF IT WOULD DROP INTO CMX...SHOULD LOWER VISIBILITIES AT LEAST TO IFR OR LOWER ALONG WITH RAMPING UP THE WINDS...AND THE CURRENT TAF FORECAST FOLLOWS THIS IDEA. THE BAND SHOULD BEGIN TO LIFT NORTH LATE TONIGHT. VFR CONDITIONS ARE EXPECTED AT SAW AFTER THE LIGHT SNOW AND FLURRIES EXIT EARLY THIS AFTERNOON. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... SW WINDS HAVE ALREADY INCREASED TO 30 KT OVER MUCH OF LAKE SUPERIOR DURING THE OVERNIGHT HOURS THANKS TO THE APPROACH OF A TROUGH NOW OVER WESTERN LAKE SUPERIOR. THIS TROUGH WILL DISSIPATE THIS MORNING...HOWEVER LURKING TO THE NW IS A STRONGER TROUGH OVER CENTRAL MANITOBA. AS THIS TROUGH APPROACHES LAKE SUPERIOR THIS AFTERNOON AND EVENING...WINDS SHOULD BE ABLE TO INCREASE TO GALES...WITH SOME GUSTS AROUND 40 KT OVER THE TYPICAL SW FLOW HIGH WIND AREA OF THE TIP OF THE KEWEENAW. WINDS SHOULD RELAX AFTER MIDNIGHT TONIGHT AS THE TROUGH DROPS INTO NORTHERN LAKE SUPERIOR AND BECOMES STATIONARY. A LOW PRESSURE AREA IS EXPECTED TO DEVELOP IN SE SASKATCHEWAN ON SUNDAY AND MOVE ACROSS LAKE SUPERIOR SUNDAY NIGHT. IN THE WAKE OF THIS LOW...NORTH WINDS MAY INCREASE UP TO 25 KT MONDAY MORNING BEFORE A WEAK RIDGE OF HIGH PRESSURE BUILDS IN FOR MONDAY NIGHT. BEYOND MONDAY NIGHT...THE WIND FORECAST IS A LITTLE UNCERTAIN...WITH THE POSSIBILITY OF A QUICK ARCTIC AIR SHOT ON TUESDAY MORNING. IF THIS PANS OUT...WE COULD BE DEALING WITH A BRIEF NW GALE ALONG WITH FREEZING SPRAY. WILL NEED TO KEEP A CLOSE EYE ON THIS. OTHERWISE...ANOTHER LOW PRESSURE AREA IS SHOWN TO MOVE UP INTO THE WESTERN GREAT LAKES REGION ON WEDNESDAY. DEPENDING ON THE EXACT TRACK...ANOTHER N TO NW GALE COULD OCCUR ON THE BACK SIDE OF THE HIGH. AT THE PRESENT TIME...THE MOST LIKELY PERIOD THIS WOULD OCCUR WOULD BE LATE WEDNESDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE SUPERIOR... GALE WARNING 1 PM TODAY TO MIDNIGHT EST TONIGHT LSZ162-263-264. GALE WARNING 4 PM TODAY TO 3 AM EST SUN LSZ265>267. GALE WARNING 4 PM TODAY TO 1 AM EST SUN LSZ243-244. LAKE MICHIGAN... GALE WARNING 4 PM TODAY TO 1 AM EST SUN LMZ248-250. && $$ DISCUSSION...DLG AVIATION/MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 529 AM CST SAT NOV 24 2007 .AVIATION... /12Z TAF ISSUANCE/ VFR LOW CLOUD CEILINGS PREVAIL AT MOST OF THE TAF SITES ATTM. MVFR CEILINGS VICINITY OF KAXN...AS WELL AS TO THE WEST AND NORTH...IN THE WAKE OF THE COLD FRONT. FRONT WILL WASH OUT TODAY WITH LOW LEVEL FLOW TURNING SOUTHWEST DURING THE LATE MORNING HOURS. BACK EDGE OF THE LOW CEILINGS A LITTLE MORE THAN A THIRD OF THE WAY ACROSS THE DAKOTAS AND BEING HANDLED POORLY BY MODEL RH AND MOS GUIDANCE. BREAKS WEST OF KHON...BETWEEN KABR AND KFAR AND WEST OF KHCO EXPECTED TO BECOME BIGGER DURING THE MORNING AS LOW LEVEL RIDGING REPLACES WEAK CYCLONIC FLOW. THEREFORE PUSHED CLEARING INTO KAXN AND KRWF AROUND NOON AND INTO KMSP BY MID AFTERNOON AND TOWARD EVENING AT KEAU. PRESSURE GRADIENT WILL BE TIGHTENING TODAY WITH GUSTS TO 18 TO 22 KNOTS FORECAST FOR THIS AFTERNOON FOR THE MN TAF SITES. VFR CONDITIONS AND A SW WIND AT 7-9 KNOTS EXPECTED FOR TONIGHT. .PREV DISCUSSION... /ISSUED 412 AM CST SAT NOV 24 2007/ THE MAIN FORECAST CONCERNS ARE CLOUD COVER TODAY AND SNOW CHANCES DURING THE EARLY/MIDDLE PORTIONS OF NEXT WEEK. 0930Z SAT WATER VAPOR IMAGERY SHOWS THE MID LEVEL TROUGH AXIS PUSHING ACROSS MN. ATTENDANT STRATUS DECK...WHICH MODELS HAVE A VERY POOR HANDLE ON...EXTENDS FROM CENTRAL MN BACK TOWARD THE CENTRAL DAKOTAS. SNOW SHOWERS CORRELATE WITH THE 20-25 DBZ ECHOES ON THE MPX RADAR...AND RUC/NAM/GFS PROGGED LIFT BETWEEN 850-700MB. WHILE THIS WEAKENS SOMEWHAT THIS MORNING...SCATTERED FLURRIES ARE STILL EXPECTED THIS MORNING...ESPECIALLY ACROSS EAST CENTRAL MN AND WEST CENTRAL WI. AS MENTIONED BEFORE...NO MODEL IS CAPTURING THE LOW LEVEL MOISTURE PROFILES ADEQUATELY THIS MORNING. MORE SPECIFICALLY...THE 00Z/24 GFS PROGGED 925MB LEVEL RH VALUES OF 45 PERCENT ACROSS EASTERN NORTH DAKOTA AT 06Z...WHERE AN OVERCAST DECK CIRCA 3K FEET WAS REALIZED. ALTHOUGH THE RH PROG WAS TOO DRY...THE 11-3.9 MICRON CHANNEL ON SATELLITE WAS BEGINNING TO SHOW THE DEVELOPMENT OF A DRY WEDGE EXPANDING INTO EASTERN NORTH DAKOTA. THEREFORE...THINK THAT THE GFS MAY BE ONTO SOMETHING...AND MAY SEE MORE CLEARING OCCURRING AHEAD OF THE BACK EDGE AS SUBSIDENCE OCCURS IN THE WAKE OF THE SHORTWAVE TROUGH. HAVE STILL GONE MORE PESSIMISTIC ON THE SKY COVER FOR TODAY...WITH CLOUDY TO MOSTLY CLOUDY CONDITIONS UNTIL THIS AFTERNOON. DUE TO THE CLOUD COVER CONCERNS...AND PERSISTENCE OVER THE LAST SEVERAL DAYS...HAVE ALSO UNDERCUT NUMERICAL GUIDANCE FOR TODAY...WITH HIGHS IN THE MID/UPPER 30S EXPECTED. IN THE WAKE OF THE TROUGH...WESTERLY/ZONAL FLOW DEVELOPS OVER THE REMAINDER OF THE WEEKEND. 925MB TEMPERATURES MODERATE TO +4 CELSIUS ACROSS MUCH OF THE CENTRAL/SOUTHWEST ON SUNDAY AFTERNOON. ANTICIPATE MOST OF THE CWA TO WARM IN THE MID/UPPER 40S ON SUNDAY...WITH BREEZY SOUTHWEST WINDS AND MOSTLY CLEAR SKIES YIELDING DECENT MIXING POTENTIAL. A FEW 50 DEGREE READINGS ARE NOT OUT OF THE QUESTION. BOTH GFS/ECMWF MODELS FEATURE A SHORTWAVE DIPPING DOWN FROM CANADA INTO THE NORTH CENTRAL CONUS ON TUESDAY/WEDNESDAY. WHILE THE AGREEMENT ON THE SURFACE TRACK/STRENGTH IS STILL UNCERTAIN...THE MAJORITY OF MEDIUM RANGE MODEL SOLUTIONS ARE INDICATIVE/SUPPORTIVE OF 30 POPS FOR SNOW FROM LATE TUESDAY THROUGH WEDNESDAY. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/LS mn AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE FORT WORTH TX 534 AM CST SAT NOV 24 2007 .AVIATION... ALL NORTH TEXAS TERMINALS WILL TREND INTO IFR CONDITIONS BY MIDDAY AND REMAIN FOR THE MOST IFR...POSSIBLE GOING LIFR...THROUGH 12Z SUNDAY. STRONG ISENTROPIC FORCING OVER MUCH OF CENTRAL AND NORTH TEXAS THIS MORNING WILL CONTINUE THROUGH TONIGHT. THE LOWER ATMOSPHERE WILL MOISTEN UP WITH TIME...LOWERING CIGS THROUGH MVFR TO IFR AROUND MIDDAY. AS THE PRECIPITATION GEARS UP LATER TODAY...CIGS AND VIS WILL FALL...AND SOMETIMES GO LIFR DURING THE AFTERNOON OR DEFINITELY THIS EVENING AND OVERNIGHT. FLIGHTS TO SOUTHWEST TEXAS...WEST TEXAS AND WESTERN OKLAHOMA WILL FIND IFR CIGS/VIS AND SNOW OR SLEET MIXED WITH RAIN TODAY TRANSITIONING TO MAINLY SNOW TONIGHT. AREAS NORTH THROUGH EAST AND SOUTH OF NORTH TEXAS WILL BE SIMILAR TO TAF CONDITIONS OF KACT OR KDFW. && PREV DISCUSSION... 452 AM CST. COMPLEX FORECAST...AS IS USUALLY THE CASE WHEN DEALING WITH POSSIBLE WINTER WEATHER IN TEXAS. OVERNIGHT MODEL FORECASTS HAVE TRENDED A LITTLE COOLER...AND LATEST RUC FORECASTS AND ACARS DATA SHOW TEMPS RIGHT AT FREEZING FROM 900 TO 700 MB OVER DFW...WITH A GRADUAL WARM-UP OCCURRING NEAR 850 MB DUE TO SOUTHERLY FLOW. MODELS ARE UNANIMOUS THAT AN 850 MB INVERTED TROUGH WILL DEVELOP TODAY AND BISECT THE CWA. ON THE SOUTHERN/WARM SIDE...TREMENDOUS WARM THERMAL/MOISTURE ADVECTION WILL OCCUR AS FLOW STRENGTHENS TO 40KT. THIS AIR WILL BE FORCED UP AND OVER THE COLD LAYER AT THE SURFACE AND ALLOW FOR WIDESPREAD RAIN AND ISOLATED THUNDERSTORMS. SOME OF THE RAIN WILL BE HEAVY IN THE SE ZONES THIS MORNING WHERE OVER AN INCH OR TWO IS POSSIBLE TODAY. ON THE NORTHERN/COLD SIDE OF THE 850 TROUGH...WINDS WILL BACK TO THE NORTHEAST AND KEEP LOW- MID LEVEL TEMPS MUCH COOLER AND FLIRTING WITH FREEZING. A WINTRY MIX IS POSSIBLE TODAY GENERALLY NW OF A SHERMAN TO EASTLAND LINE. SURFACE TEMPERATURES WILL BE IN THE MID-UPPER 30S AND NO SNOW/ICE ACCUMULATIONS THROUGH EARLY THIS EVENING ARE EXPECTED. MODELS SUGGEST AN ABOVE FREEZING LAYER /OR WARM NOSE/ WILL DEVELOP AND ENCOMPASS ALL OF THE NORTHWESTERN ZONES TONIGHT. MEANWHILE AFTER A BRIEF RESPITE THIS AFTERNOON FROM THE WIDESPREAD RAIN... ANOTHER ROUND OF SIGNIFICANT PRECIPITATION WILL BE DEVELOPING AHEAD OF THE UPPER LEVEL LOW AFTER SUNSET. THIS PRECIPITATION WILL BE ALL SNOW IN THE CLOUDS...BUT WILL HAVE TROUBLE REACHING THE SURFACE DUE TO THE LAYER OF ABOVE FREEZING TEMPS. HOWEVER... THE MELTING OF FROZEN HYDROMETEORS OVER TIME WILL FORCE THE TEMPERATURE TO FREEZING AS LATENT HEAT IS ABSORBED. THIS IS LIKELY TO HAPPEN UNDER BANDS OF INTENSE PRECIPITATION...WHICH THE MODELS DO INDICATE OVER THE NW HALF OF THE CWA TONIGHT. MODEL SOUNDINGS AND PARTIAL THICKNESS ANALYSIS SHOWS A RAIN/SNOW MIX NW OF A COMANCHE TO BOWIE LINE TONIGHT. HEAVY BURSTS OF SNOW COULD OCCUR AND THIS WOULD RESULT IN A QUICK ACCUMULATION OF SNOW ON THE GROUND. THEREFORE...WE HAVE ISSUED A WINTER WEATHER ADVISORY FROM 9 PM TO 9 AM FOR THE NW COUNTIES AS TRAVEL COULD BE IMPACTED FOR A FEW HOURS. GROUND TEMPS ARE WARM AND COLD ADVECTION IS LACKING SO WOULD EXPECT ANY ACCUMULATION TO GRADUALLY MELT AWAY SUNDAY. HAVE INCLUDED LIGHT SNOW AND FLURRIES IN THE CENTRAL ZONES EARLY SUNDAY AS THERE COULD BE A FEW SNOWFLAKES THAT SURVIVE THE TRIP DOWN...BUT WARM LAYER SHOULD BE MORE STOUT. SURFACE TEMPS OVER THE CENTRAL ZONES SHOULD REMAIN ABOVE FREEZING WITH LITTLE IMPACT EXPECTED. AS THE UPPER LEVEL LOW MOVES INTO WEST CENTRAL TEXAS...MUCH OF THE CWA WILL GET DRY SLOTTED WITH SIGNIFICANT RAINS ENDING SUNDAY MORNING AND HAVE DIALED DOWN THE POPS SUNDAY AFTERNOON. GFS/ECMWF SHOW UPPER LEVEL LOW TRACKING RIGHT OVER NW ZONES SUNDAY EVENING AND WITH SUBSTANTIAL COOLING FORCED VIA DYNAMIC LIFTING...A CHANGE TO ALL SNOW IS POSSIBLE NW OF A SHERMAN TO EASTLAND LINE. THERE COULD BE SOME ACCUMULATIONS OF WRAPAROUND SNOW AS THE UPPER LOW EXITS. STILL 36-48 HOURS AWAY...SO WILL PLAY IT CONSERVATIVE. AFTER THE UPPER LOW EXITS WE WILL SEE A QUICK WARM UP WITH SW FLOW IN THE LOW LEVELS. ANOTHER FRONT IS EXPECTED WEDNESDAY WITH A SLIGHT CHANCE OF RAIN AND A COOL DOWN. LOW RAIN CHANCES WILL RETURN AT THE END OF THE WEEK AHEAD OF A PACIFIC UPPER LOW. TR.92 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 43 37 43 36 60 / 100 100 50 50 10 WACO, TX 44 38 45 38 60 / 100 100 50 20 10 PARIS, TX 43 37 43 37 55 / 100 100 80 60 10 DENTON, TX 42 36 42 35 60 / 100 100 50 50 10 MCKINNEY, TX 42 37 43 36 58 / 100 100 50 50 10 DALLAS, TX 43 37 43 37 59 / 100 100 50 50 10 TERRELL, TX 43 38 44 39 59 / 100 100 60 50 10 CORSICANA, TX 43 39 45 37 60 / 100 100 60 30 10 TEMPLE, TX 44 38 45 36 61 / 100 100 50 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST SUNDAY FOR THE FOLLOWING ZONES: TXZ091-100-101-115-116-129. && $$ 92/75 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 452 AM CST SAT NOV 24 2007 .DISCUSSION... COMPLEX FORECAST...AS IS USUALLY THE CASE WHEN DEALING WITH POSSIBLE WINTER WEATHER IN TEXAS. OVERNIGHT MODEL FORECASTS HAVE TRENDED A LITTLE COOLER...AND LATEST RUC FORECASTS AND ACARS DATA SHOW TEMPS RIGHT AT FREEZING FROM 900 TO 700 MB OVER DFW...WITH A GRADUAL WARM-UP OCCURRING NEAR 850 MB DUE TO SOUTHERLY FLOW. MODELS ARE UNANIMOUS THAT AN 850 MB INVERTED TROUGH WILL DEVELOP TODAY AND BISECT THE CWA. ON THE SOUTHERN/WARM SIDE...TREMENDOUS WARM THERMAL/MOISTURE ADVECTION WILL OCCUR AS FLOW STRENGTHENS TO 40KT. THIS AIR WILL BE FORCED UP AND OVER THE COLD LAYER AT THE SURFACE AND ALLOW FOR WIDESPREAD RAIN AND ISOLATED THUNDERSTORMS. SOME OF THE RAIN WILL BE HEAVY IN THE SE ZONES THIS MORNING WHERE OVER AN INCH OR TWO IS POSSIBLE TODAY. ON THE NORTHERN/COLD SIDE OF THE 850 TROUGH...WINDS WILL BACK TO THE NORTHEAST AND KEEP LOW- MID LEVEL TEMPS MUCH COOLER AND FLIRTING WITH FREEZING. A WINTRY MIX IS POSSIBLE TODAY GENERALLY NW OF A SHERMAN TO EASTLAND LINE. SURFACE TEMPERATURES WILL BE IN THE MID-UPPER 30S AND NO SNOW/ICE ACCUMULATIONS THROUGH EARLY THIS EVENING ARE EXPECTED. MODELS SUGGEST AN ABOVE FREEZING LAYER /OR WARM NOSE/ WILL DEVELOP AND ENCOMPASS ALL OF THE NORTHWESTERN ZONES TONIGHT. MEANWHILE AFTER A BRIEF RESPITE THIS AFTERNOON FROM THE WIDESPREAD RAIN... ANOTHER ROUND OF SIGNIFICANT PRECIPITATION WILL BE DEVELOPING AHEAD OF THE UPPER LEVEL LOW AFTER SUNSET. THIS PRECIPITATION WILL BE ALL SNOW IN THE CLOUDS...BUT WILL HAVE TROUBLE REACHING THE SURFACE DUE TO THE LAYER OF ABOVE FREEZING TEMPS. HOWEVER... THE MELTING OF FROZEN HYDROMETEORS OVER TIME WILL FORCE THE TEMPERATURE TO FREEZING AS LATENT HEAT IS ABSORBED. THIS IS LIKELY TO HAPPEN UNDER BANDS OF INTENSE PRECIPITATION...WHICH THE MODELS DO INDICATE OVER THE NW HALF OF THE CWA TONIGHT. MODEL SOUNDINGS AND PARTIAL THICKNESS ANALYSIS SHOWS A RAIN/SNOW MIX NW OF A COMANCHE TO BOWIE LINE TONIGHT. HEAVY BURSTS OF SNOW COULD OCCUR AND THIS WOULD RESULT IN A QUICK ACCUMULATION OF SNOW ON THE GROUND. THEREFORE...WE HAVE ISSUED A WINTER WEATHER ADVISORY FROM 9 PM TO 9 AM FOR THE NW COUNTIES AS TRAVEL COULD BE IMPACTED FOR A FEW HOURS. GROUND TEMPS ARE WARM AND COLD ADVECTION IS LACKING SO WOULD EXPECT ANY ACCUMULATION TO GRADUALLY MELT AWAY SUNDAY. HAVE INCLUDED LIGHT SNOW AND FLURRIES IN THE CENTRAL ZONES EARLY SUNDAY AS THERE COULD BE A FEW SNOWFLAKES THAT SURVIVE THE TRIP DOWN...BUT WARM LAYER SHOULD BE MORE STOUT. SURFACE TEMPS OVER THE CENTRAL ZONES SHOULD REMAIN ABOVE FREEZING WITH LITTLE IMPACT EXPECTED. AS THE UPPER LEVEL LOW MOVES INTO WEST CENTRAL TEXAS...MUCH OF THE CWA WILL GET DRY SLOTTED WITH SIGNIFICANT RAINS ENDING SUNDAY MORNING AND HAVE DIALED DOWN THE POPS SUNDAY AFTERNOON. GFS/ECMWF SHOW UPPER LEVEL LOW TRACKING RIGHT OVER NW ZONES SUNDAY EVENING AND WITH SUBSTANTIAL COOLING FORCED VIA DYNAMIC LIFTING...A CHANGE TO ALL SNOW IS POSSIBLE NW OF A SHERMAN TO EASTLAND LINE. THERE COULD BE SOME ACCUMULATIONS OF WRAPAROUND SNOW AS THE UPPER LOW EXITS. STILL 36-48 HOURS AWAY...SO WILL PLAY IT CONSERVATIVE. AFTER THE UPPER LOW EXITS WE WILL SEE A QUICK WARM UP WITH SW FLOW IN THE LOW LEVELS. ANOTHER FRONT IS EXPECTED WEDNESDAY WITH A SLIGHT CHANCE OF RAIN AND A COOL DOWN. LOW RAIN CHANCES WILL RETURN AT THE END OF THE WEEK AHEAD OF A PACIFIC UPPER LOW. TR.92 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 43 37 43 36 60 / 100 100 50 50 10 WACO, TX 44 38 45 38 60 / 100 100 50 20 10 PARIS, TX 43 37 43 37 55 / 100 100 80 60 10 DENTON, TX 42 36 42 35 60 / 100 100 50 50 10 MCKINNEY, TX 42 37 43 36 58 / 100 100 50 50 10 DALLAS, TX 43 37 43 37 59 / 100 100 50 50 10 TERRELL, TX 43 38 44 39 59 / 100 100 60 50 10 CORSICANA, TX 43 39 45 37 60 / 100 100 60 30 10 TEMPLE, TX 44 38 45 36 61 / 100 100 50 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST SUNDAY FOR THE FOLLOWING ZONES: TXZ091-100-101-115-116-129. && $$ 92/75 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 404 PM EST SAT NOV 24 2007 .DISCUSSION...LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW A MID-LEVEL WAVE PASSING ACROSS THE CWA ATTM WITH MID-UPPER LEVEL CLOUDS EXITING TO THE EAST. SOME DRIER LOW LEVEL AIR HAS BEEN SURGING NE ACROSS SOUTHERN LOWER MICHIGAN THIS AFTERNOON AND CREATING A FEW HOLES IN THE CLOUD COVER ACROSS THE SOUTHEAST CORNER OF THE CWA. BUT THE MAIN SHOW HAS BEEN THE SW LAKE EFFECT SNOW EVENT THAT CONTINUES TO IMPACT THE TIP OF THE MITT AND EASTERN UPPER MICHIGAN. SNOW REPORTS ACROSS EMMETT...CHEBOYGAN...AND MACKINAC COUNTIES INDICATED 3-6 INCHES OF SNOW HAVE FALLEN SINCE THIS MORNING WITH THE HEAVIEST SNOW LOCATED WITHIN A CORRIDOR BETWEEN HARBOR SPRINGS AND LEVERING. EM IN MACKINAC COUNTY REVEALED NUMEROUS ACCIDENTS ALONG M-134 NEAR CEDARVILLE WHERE 3 INCHES OF NEW SNOW HAS FALLEN SINCE THIS MORNING. AS THE MID-UPPER LEVEL MOISTURE EXITS...PLENTY OF LOW CLOUDS ACROSS WISCONSIN ARE IN THE PROCESS OF CROSSING NORTHERN LAKE MICHIGAN. ACARS SOUNDINGS REVEAL INVERSION HEIGHTS REMAIN AROUND 9KFT BUT LOWER FAIRLY QUICKLY OVER NORTH CENTRAL WISCONSIN TO ABOUT 4KFT. MEANWHILE...VARIOUS SHIP REPORTS AND BUOYS INDICATE AN OCCASIONAL GALE FORCE GUST IS OCCURRING OVER THE NORTHERN LAKE MICHIGAN AND LAKE HURON. LAKE EFFECT AND MARINE HEADLINES ARE THE MAIN FORECAST CONCERNS THROUGH TOMORROW. TONIGHT...WEAK SHEARED OUT SHORTWAVE WILL MOVE EAST OF THE REGION AND WILL DRAG ALL THE MID-HIGH LEVEL MOISTURE WITH IT. 850-700MB RH OVER NORTHERN LAKE MICHIGAN WILL DECREASE FROM 45-65 PCT EARLY THIS EVENING TO 35-45 PCT BY OVERNIGHT WHILE INVERSION HEIGHTS CRASH FROM 8KFT TO UNDER 3KFT...WITH MOST OF THE CRASHING OCCURRING DURING THE EVENING. 850MB TEMPS ALSO MODERATE FROM THEIR NEAR -8C LEVELS THIS AFTERNOON TO ABOUT -4C BY 12Z. THESE PARAMETERS SUGGEST A DIMINISHING TREND IN LES ACTIVITY THIS EVENING AND COMPLETELY SHUTTING OFF BY 12Z. WITH THE BACK EDGE OF THE DEEPER MOISTURE NOW REACHING WESTERN LAKE MICHIGAN...WILL MAKE A LAST MINUTE DECISION WHETHER TO EXTEND HEADLINES THROUGH THE EVENING. EITHER WAY...WILL BUMP UP SNOW CHANCES TO NUMEROUS ACROSS EMMET/CHEBOYGAN AND EASTERN CHIP COUNTIES THROUGH MID-EVENING...BEFORE TRIMMING TO FLURRIES OVERNIGHT. ADDITIONAL ACCUMULATIONS WILL BE UP TO AN INCH MOSTLY BETWEEN HARBOR SPRINGS AND LEVERING. ELSEWHERE...SHALLOW LOW LEVEL MOISTURE OVER WISCONSIN WILL ROTATE ACROSS THE CWA THIS EVENING BEFORE EXITING BY 12Z SUN. MID-UPPER LEVEL CLOUDS WILL SKIRT BY THE AREA TO THE NORTH...SO WILL KEEP SKIES MOSTLY CLOUDY NORTH OF THE STRAITS THE ENTIRE NIGHT. LOWS WILL BE IN THE MIDDLE TO UPPER 20S. TOMORROW...SHORTWAVE MOVING ACROSS ONTARIO WILL GET SHEARED APART AS IT MOVES EAST INTO QUEBEC...BUT NOT BEFORE DROPPING A COLD FRONT ACROSS SOUTHERN ONTARIO JUST NORTH OF LAKE SUPERIOR. TO THE SOUTH OF THE COLD FRONT...SW WINDS AND WAA WILL CONTINUE TO BRING UP 850MB TEMPS TO THE -3C TO 0C RANGE DURING THE DAY. MID-UPPER LEVEL CLOUDS BROUGHT IN BY THE JET STREAM WILL SLOWLY RETREAT TO THE NORTH WHILE THE 850-700MB RH FALLS BETWEEN 25-35 PCT BY THE END OF THE DAY. LOW LEVEL INSTABILITY PROBABLY IS STILL SUFFICIENT FOR SOME LAKE CLOUDS ACROSS SW FLOW REGIMES IN THE MORNING BEFORE THE INFLUX OF DRIER AIR AND DIURNAL MIXING CAUSE THESE CLOUDS TO DIMINISH. THEREFORE...A GENERAL DECREASING CLOUDINESS TREND WILL BE OBSERVED AND WILL KEEP DRY CONDITIONS GOING...WITH HIGHS IN THE MID 30S NORTH TO MID 40S SW. MPC SUNDAY NIGHT THROUGH TUESDAY...CHANGEABLE WEATHER LOOKS ON TAP FOR THIS PERIOD. INITIAL FOCUS COMES LATE SUNDAY NIGHT INTO EARLY MONDAY ACROSS THE NORTH AS WEAK NORTHERN STREAM ENERGY AND LOW LEVEL RIDGING PUSHING THROUGH THE PLAINS ATTEMPTS TO SHOVE A WEAK FRONTAL BOUNDARY ACROSS THE UPPER PENINSULA. NOT MUCH IN THE WAY OF MOISTURE TO WORK WITH...BUT PRONOUNCED AREA OF 900-800MB FRONTOGENESIS GIVEN VERY TIGHT THERMAL GRADIENT IN PLACE (READINGS LIKELY IN THE LOWER TEENS ACROSS SOUTHERN ONTARIO) WILL PROBABLY BE SUFFICIENT TO SQUEEZE OUT A FEW LIGHT SNOW SHOWERS AS WELL AS PROVIDE AN INCREASE IN CLOUDS. FARTHER SOUTH ACROSS NORTHERN LOWER...NOT A HALF BAD DAY EXPECTED ON MONDAY AS AREA FALLS IN BETWEEN SYSTEMS - FRONT TO THE NORTH AND DEVELOPING LOW OVER THE OHIO VALLEY WITH UPPER WAVE OVER FAR NORTHWESTERN MEXICO THIS AFTERNOON KICKING OUT THROUGH THE PLAINS. TEMPERATURE-WISE...LOOKS FAIRLY "WARM" WITH H85 TEMPS MODERATING TO AROUND -1C UNDER BROAD SOUTHWESTERLY FLOW...AND WITH AT LEAST SOME SUNSHINE EXPECTED...HIGHS IN THE UPPER 30S/LOWER 40S A PRETTY GOOD BET. THINGS HEAD DOWNHILL ACROSS THE FAR SOUTH BY LATE AFTERNOON AS AFOREMENTIONED UPPER WAVE LIFTS INTO THE OHIO VALLEY...WITH INCREASING 700-500MB -DIVQ AXIS AND MID LEVEL BAND OF FRONTOGENESIS ATTEMPTING TO SPREAD INTO THE REGION. STILL A FEW QUESTIONS TO BE ANSWERED WITH THIS SYSTEM...NAMELY JUST WHERE WILL PRECIP END UP AND WHAT TYPE WILL IT BE? GIVEN NATURE OF PRECIP DRIVEN BY FGEN...WOULD OBVIOUSLY EXPECT A SHARP CUTOFF...AND NUMERICAL GUIDANCE (INCLUDING 15Z SREF) HAS BEEN ADAMANT ABOUT JUST BRUSHING THE FAR SOUTHEAST WITH THE SYNOPTICALLY-DRIVE PRECIP. FORECAST RAOBS AND EXPECTED WARMISH START LEAD TO A CONTINUED MENTION OF RAIN WITH THE LOWEST 2KFT PROGGED ABOVE FREEZING. HOWEVER...COLD AIR NOT FAR AWAY (REFERENCE ABOVE) AND WOULD EXPECT ANYTHING THAT CONTINUES TO CHANGE TO SNOW QUITE QUICKLY. SYSTEM LOOKS SIMILAR TO WHAT OCCURED LAST WEEK...ONLY MORE SUPPRESSED BUT STILL SOMETHING TO BE WATCHED CLOSELY. BETTER SHOT AT PRECIP FOR MORE OF THE REGION APPEARS TO COME ON TUESDAY AS SECONDARY PIECE OF NORTHERN STREAM ENERGY PROGGED TO DIVE DIRECTLY ACROSS THE GREAT LAKES. ECMWF HAS REMAINED CONSISTENT WITH THIS TREND...AND HAS THE SUPPORT OF THE 00/12Z GEFS MEAN. IN TYPICALLY CLIPPER FASHION...THIS ONE MAY TURN OUT TO BE A BIT OF A NUISANCE GIVEN PROGGED DECENT 850-700MB FRONTOGENETICAL AXIS SETTING UP SOMEWHERE NEAR THE AREA...WHILE LAKE ENHANCEMENT COMES INTO PLAY PER H85 TEMPS RUNNING ABOUT -13C OR SO. THAT IS...ASSUMING THE ECMWF IS ONTO THE RIGHT IDEA...AS THE GFS WOULD SUGGEST A MUCH FLATTER WAVE PASSING HARMLESSLY TO THE NORTH. THE KEY APPEARS TO BE THE DEGREE OF RIDGING TAKING SHAPE OVER THE PACIFIC/CANADIAN NORTHWEST...WHICH THE GFS/ECMWF ENSEMBLE MEANS WOULD SUGGEST WILL BE SUFFICIENT TO ALLOW THE NORTHERN STREAM ENERGY TO PENETRATE FARTHER SOUTH. GIVEN SOME REMAINING UNCERTAINTIES...PREFER TO HOLD WITH SMALL POPS AT THIS JUNCTURE. LATER PERIODS (TUESDAY NIGHT THROUGH SATURDAY)...ANOTHER CHALLENGING FORECAST IN THE WORKS FOR THE EXTENDED...WITH QUESTIONS ABOUNDING WITH REGARDS TO PRECIP CHANCES AS WELL AS DAILY TEMPERATURES. OVERALL PATTERN THROUGH THIS PERIOD LOOKS TO BE DOMINATED BY AN ACTIVE NORTHERN STREAM...WHILE SOUTHERN STREAM ENERGY LURKS NOT TOO FAR AWAY. INITIAL CHALLENGE COMES WEDNESDAY NIGHT INTO THURSDAY WITH PACIFIC ENERGY PROGGED TO DROP THROUGH THE CENTRAL ROCKIES... INCITING LEE CYCLOGENESIS OVER THE CENTRAL HIGH PLAINS. THIS LOW IS THEN EXPECTED TO TRACK NORTHEAST ALONG TIGHTENING THERMAL GRADIENT AS FIRST SURGE OF ARCTIC AIR POURS INTO THE NORTHERN PLAINS PER DEVELOPING STRONG BLOCKING RIDGE ACROSS INTERIOR ALASKA. MODEL SOLUTIONS QUITE VARIED WITH REGARDS TO EXACTLY HOW THIS WHOLE THING WILL PLAY OUT...WITH THE GFS DEPICTING A WEAK SURFACE FEATURES WHILE THE ECMWF/CANADIAN KEYS IN ON A MUCH MORE PHASED/AMPLIFIED UPPER SYSTEM...AND A MORE PRONOUNCED ACCOMPANYING SURFACE SYSTEM. LIKELY STRONG THERMAL GRADIENT WOULD CERTAINLY ARGUE TO A MORE WOUND UP SYSTEM...AND ALONG THE LINES OF HPC...PREFER TO SIDE WITH THE ECMWF THIS GO AROUND. EITHER WAY...HOWEVER...THE END RESULT WILL BE HEIGHTENED CHANCES FOR PRECIP AS ISENTROPIC ASCENT REVVS UP LATE WEDNESDAY AND UPPER FORCING CATCHES UP ON THURSDAY TO SHOVE WHAT SHOULD BE A RATHER POTENT COLD FRONT THROUGH THE REGION. PER FORECAST RAOBS OF EITHER SCENARIO...PTYPE LOOKS TO BE MAINLY SNOW...THOUGH PENDING EXACT TRACK/STRENGTH OF SYSTEM...COULD FORESEE SOME RAIN ENTERING THE PICTURE AS WARMER AIR TRIES TO SNEAK IN AHEAD OF THE COLD FRONT. HEADING INTO THURSDAY AFTERNOON THROUGH SATURDAY...APPEARS THE LAKE EFFECT MACHINE WILL BE GOING FULL FORCE AS INITIAL SHOT OF QUITE COLD AIR (H85 TEMPS PROGGED -16C TO -18C) DROPS INTO THE REGION PER BRIEF CROSS-POLAR SETUP WITH POLAR VORTEX DROPPING ACROSS HUDSON BAY WHILE STRONG ALASKA RIDGE HOLDS FIRM. SETUP NOT OVERLY STABLE... HOWEVER...AS ENERGY PROGGED TO BRIEFLY DISRUPT THE OVERALL MEAN RIDGE OVER ALASKA...WHILE SECONDARY ENERGY DROPS INTO THE WESTERN CONUS...EFFECTIVELY SHUNTING THE INTIAL SHOT OF COLD EAST. THAT SAID...WILL CONTINUE TO CARRY LAKE EFFECT SNOW SHOWER MENTION THROUGH THE ENTIRE PERIOD FOR WEST/NORTHWEST FLOW LOCATIONS AS OVERLL CYCLONE FLOW REGIME PERSISTS AND MOISTURE REMAINS SUFFICIENTLY DEEP (900-700MB RH GREATER THAN 70 PERCENT). AS FOR TEMPERATURES EACH DAY...WILL SHOW FALLING TEMPS THURSDAY AFTERNOON AS PLENTIFUL COLD ADVECTION UNDERWAY...WITH READINGS ONLY IN THE 20S ON FRIDAY UNDER CLOUDS/SNOW SHOWERS. LOOKING AHEAD JUST BIT MORE...PERHAPS AN EVEN BIGGER STORY LOOMS JUST AFTER THE CURERNT FORECAST PERIOD ENDS...WITH ALL MODEL GUIDANCE REMAINING IN VERY GOOD AGREEMENT REGARDING REDEVELOPMENT (AND BETTER SUSTAINMENT) OF CROSS POLAR FLOW INTO THE NORTHERN TIER OF THE U.S. AS VERY STRONG RIDGING ONCE AGAIN BUILDS THROUGH ALASKA...WITH ANOTHER SHOT OF VERY COLD AIR MAKING AN APPEARANCE TOWARD THE END OF THE WEEKEND. LAWRENCE && .PREV DISCUSSION... /ISSUED 1215 PM EST SAT NOV 24 2007/ AVIATION...PERSISTENT LOW LEVEL SW FLOW COUPLED WITH A SHORT WAVE AND SURFACE RESPONSE MOVING THRU NRN MICHIGAN WILL PRODUCE LAKE ENHANCED SNOW SHOWERS OVER THE NEXT 12 HOURS. THE HEAVIEST AND MOST PERSISTENT SNOWFALL WILL TARGET THE STRAITS AREA AND THE FAR NORTHWEST LOWER MICHIGAN SHORELINE (KPLN). IFR TO LIFR CONDITIONS CAN BE EXPECTED AT KPLN THROUGH THIS EVENING...WITH PERIODIC HEAVY SNOW SHOWERS EXPECTED TO DROP VSBYS TO A 1/2SM OR LESS. TVC WILL ALSO SEE OCCASIONAL IFR VSBYS IN LESS PERSISTENT SNOW SHOWERS WHILE APN LOOKS VFR THROUGH THE DAY. SNOW SHOWERS WILL WIND DOWN THIS EVENING BEFORE DIMINISHING OVERNIGHT. WINDY CONDITIONS WILL PERSIST THROUGH TOMORROW. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 11 PM EST THIS EVENING FOR MIZ015-017-019. LAKE EFFECT SNOW WARNING UNTIL 11 PM EST THIS EVENING FOR MIZ016. LM...GALE WARNING UNTIL 11 AM EST SUNDAY FOR LMZ323-341-342-344>346. LH...GALE WARNING UNTIL 11 AM EST SUNDAY FOR LHZ345>349. LS...GALE WARNING UNTIL 5 AM EST SUNDAY FOR LSZ321. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1215 PM EST SAT NOV 24 2007 AVIATION...PERSISTENT LOW LEVEL SW FLOW COUPLED WITH A SHORT WAVE AND SURFACE RESPONSE MOVING THRU NRN MICHIGAN WILL PRODUCE LAKE ENHANCED SNOW SHOWERS OVER THE NEXT 12 HOURS. THE HEAVIEST AND MOST PERSISTENT SNOWFALL WILL TARGET THE STRAITS AREA AND THE FAR NORTHWEST LOWER MICHIGAN SHORELINE (KPLN). IFR TO LIFR CONDITIONS CAN BE EXPECTED AT KPLN THROUGH THIS EVENING...WITH PERIODIC HEAVY SNOW SHOWERS EXPECTED TO DROP VSBYS TO A 1/2SM OR LESS. TVC WILL ALSO SEE OCCASIONAL IFR VSBYS IN LESS PERSISTENT SNOW SHOWERS WHILE APN LOOKS VFR THROUGH THE DAY. SNOW SHOWERS WILL WIND DOWN THIS EVENING BEFORE DIMINISHING OVERNIGHT. WINDY CONDITIONS WILL PERSIST THROUGH TOMORROW. MPC && .UPDATE...ISSUED AT 1038 AM EST SAT 12Z SURFACE/RUC ANALYSIS AND VIS/IR/WV/RADAR ANALYSIS SHOW NORTHERN MICHIGAN LYING BETWEEN SURFACE HIGH PRESSURE OVER THE MID-ATLANTIC STATES AND LOW PRESSURE OVER NORTHERN ONTARIO. WEAK MID-LEVEL WAVE IS CUTTING ACROSS THE UPPER MIDWEST THIS MORNING AND MID-UPPER LEVEL MOISTURE IS SPREADING ACROSS WESTERN WISCONSIN/SOUTHERN U.P./AND LOWER MICHIGAN IN A POCKET OF WEAK -DIVQ. 12Z APX SOUNDING SHOWS A MOIST PROFILE ABOVE 700MB WITH SUBTLE WARMING IN THE LOW LEVELS IN A WAA REGIME THAT HAS HELPED 850MB TEMPS WARM TO -9C. UPSTREAM 12Z GRB SOUNDING SHOWS A SIMILAR TALE WITH SLIGHTLY WARMER 850MB TEMPS AROUND -7C AND A MOIST PROFILE ABOVE 900MB. THIS MOISTURE COMBINED WITH DELTA T/S AROUND 17C AND INVERSION HEIGHTS AROUND 6KFT HAS ALLOWED SW BAND OF LES TO CONTINUE RIGHT ALONG THE LAKE MICHIGAN SHORELINE FROM NORTHPORT TO PELLSTON WITH A SLIGHT UPTICK IN INTENSITY OVER THE PAST HOUR. MEANWHILE...WITH THE TIGHT GRADIENT IN PLACE...WIND GUSTS AT THE NORTHERN LAKE MICHIGAN BUOY HAVE BEEN SLOWING INCREASING INTO THE UPPER 20S THIS MORNING. MAIN FORECAST CONCERNS CONTINUE TO REVOLVE AROUND LAKE EFFECT AND MARINE HEADLINES. NO MAJOR CHANGES PLANNED TO THE CURRENT FORECAST IN RESPECT TO HEADLINES. MID-LEVEL SHORTWAVE WILL MOVE EAST OVER THE REST OF THE DAY WITH 850-700MB RH REMAINING ABOVE 90 PCT AHEAD OF IT WHILE INVERSION HEIGHTS INCREASE TO AROUND 8-9KFT WITH THE WAVE PASSAGE JUDGING BY UPSTREAM ACARS DATA OVER CENTRAL WISCONSIN. DELTA T`S MAY TAKE A SLIGHT HIT TODAY BY A DEGREE OR SO WHICH WOULD PLACE 850MB TEMPS AROUND -7 TO -8C AND DELTA T`S APPROX. 16-17C. THESE PARAMETERS SUGGEST THAT LES ACTIVITY WILL REMAIN ABOUT STATUS QUO THROUGH THE AFTERNOON WITH 1000-850MB WINDS REMAINING ABOUT 240 DEGREES...WHICH WOULD TARGET CHARLEVOIX...EMMET...CHEBOYGAN...AND SOUTHERN MACKINAC COUNTIES. THERE IS STILL SOME CONCERN THAT WARMING TEMPS THIS AFTERNOON COULD LIMIT ACCUMULATIONS SOMEWHAT...ESPECIALLY RIGHT ALONG THE LAKESHORE. SURFACE TEMPS AT AT HARBOR SPRINGS IS AT 34 DEGREES AT 9 AM WHILE LOCAL GUIDANCE SUGGESTS PRECIP TYPE WITH 850MB TEMPS AROUND -8C AND LAKE TEMP AT 9C RIGHT AROUND THE SNOW/MIX LINE. HOWEVER...BELIEVE THIS WILL BE OFFSET BY THE RECENT SNOW PACK AND DYNAMIC COOLING OF THE BL WHICH WILL ALLOW SURFACE TEMPS TO REMAIN STEADY AND SNOWFALL TO ACCUMULATE. CURRENT GRIDS HAVE 3-5 INCHES THIS AFTERNOON FROM CHARLEVOIX TO EMMET TO MACKINAC COUNTIES...AND THIS CONTINUES TO LOOK GOOD. WILL HAVE TO KEEP AN EYE ON NW CHARLEVOIX COUNTY FOR POTENTIAL HEADLINE UPGRADE IF THE CURRENT BAND DOES NOT MOVE TOO MUCH. WHERE THERE IS LITTLE TO NO SNOW PACK FROM MANISTEE UP TO LEELANAU COUNTIES...HAVE PLACE A MIX ALONG THE LAKE SHORES IN FOR THE AFTERNOON AS SURFACE TEMPS ARE IN THE 34-36F RANGE. MARINE...WINDS IN THE MIXED LAYER WILL CONTINUE TO INCREASE THIS AFTERNOON INTO THE 35-45 KT RANGE WHICH WILL LAST THROUGH TONIGHT. WITH THE CURRENT UNSTABLE CONDITIONS OVER THE LAKE...BELIEVE GALE FORCE GUST WILL BE ACHIEVED LATER TODAY INTO TONIGHT. GALES MAY VERY WELL CONTINUE INTO TOMORROW AS WELL...BUT WILL MAKE THOSE DECISIONS IN THE 4PM ISSUANCE. ZONES OUT SHORTLY. MPC && .DISCUSSION...ISSUED 346 AM EST SAT SW FLOW LAKE EFFECT EVENT CONTINUES EARLY THIS MORNING. WIDESPREAD SNOW SHOWERS CONTINUE TO IMPACT THE STRAITS AREA...BUT HAS SHOWS A DOWNWARD TREND IN BOTH AREAL COVERAGE AND INTENSITY AS A QUICK SHOT OF DRIER AIR SWEEPS THRU THE REGION. DOWNWARD TREND WILL BE SHORT-LIVED AS DEEP MOISTURE AND SYNOPTIC LIFT APPROACHES OUR CWA THIS MORNING AHEAD OF A SHORT WAVE AND WEAK SURFACE RESPONSE. IMPACT THAT THIS SYSTEM WILL HAVE ON THE ONGOING SW FLOW LAKE EFFECT EVENT WILL BE THE MAIN FORECAST FOCUS FOR THE NEXT 24 HOURS...SPECIFICALLY REGARDING POPS AND ADDITIONAL SNOW ACCUMULATIONS. LAST HALF OF THE WEEKEND WILL FEATURE A BREAK IN THE ACTION AS DRIER AND WARMER AIR MOVES INTO THE REGION. TODAY AND TONIGHT...DEEP MOISTURE WILL SPREAD EASTWARD INTO OUR CWA THIS MORNING...AND REMAIN IN PLACE THRU THE AFTERNOON. LAST COUPLE OF IMAGES FROM KAPX 88D INDICATES THE INITIAL STAGES OF MID LEVEL MOISTENING ACROSS NW PORTIONS OF OUR CWA. ENHANCED MID LEVEL MOISTURE EXTENDS ALL THE WAY BACK THRU WRN UPPER MICHIGAN AND MUCH OF WISCONSIN PER UPSTREAM RADARS AND IR SATELLITE IMAGES. SW FLOW LAKE EFFECT EVENT IS QUICKLY BECOMING ENHANCED BY INCREASING SYNOPTIC MOISTURE AND LIFT VIA THE APPROACHING SHORT WAVE. DELTA T`S REMAIN IN THE MID TO UPPER TEENS THRU THIS EVENING. 1000-500 MB RH INCREASES TO AROUND 95 PCT BY 18Z TODAY...AS INVERSION HEIGHTS CLIMB TO AROUND 10 KFT. MAX 700-500 MB DIV-Q WILL BE SLIGHTLY DELAYED TOWARD EVENING...AT WHICH TIME RH WILL BE DECREASING AND LOW LEVEL WAA WILL BEGIN TO ERODE OVER-LAKE INSTABILITY. NEVERTHELESS...EXPECT THE STRAITS AREA AND FAR NW LAKE MICHIGAN SHORELINE AREAS WILL SEE AN ADDITIONAL 3 TO 5 INCHES OF SNOW TODAY...WITH THE HEAVIEST AND MOST PERSISTENT SNOW FALLING ACROSS EMMET...CHEBOYGAN AND MACKINAC COUNTIES. WILL MAINTAIN ONGOING HEADLINES FOR THESE COUNTIES. WILL ALSO ISSUE AN ADVISORY FOR CHARLEVOIX COUNTY FOR TODAY AS WRN PORTIONS OF THE COUNTY COULD SEE UP TO 4 INCHES OF NEW SNOW. HAVE REWORKED GRIDS FOR TODAY TO INCREASE POPS AND EXPECTED SNOW AMOUNTS. WILL NEED TO KEEP AN EYE ON PRECIP TYPE THROUGHOUT THE DAY AND EVEN INTO THIS EVENING AS MODEL SOUNDINGS SHOW SURFACE-BASED WARM LAYER WILL TRY TO DEEPEN TO NEAR 2 KFT BY EVENING. HOWEVER...THINK DYNAMIC COOLER AND POTENTIAL FOR HEAVIER PRECIP MAY OFFSET ANY LOW LEVEL WAA ENOUGH TO KEEP PRECIP OF THE FROZEN VARIETY. DRY AIR...SUBSIDENCE... FALLING INVERSION HEIGHTS AND LOW LEVEL WAA/DIMINISHING OVER-LAKE INSTABILITY WILL LIMIT POPS TO CHANCE FOR TONIGHT FOR W/SW FLOW AREAS...WITH ADDITIONAL SNOW ACCUMULATION REMAINING AOB AN INCH. FOR MARINE INTERESTS...WILL MAINTAIN GALE WARNINGS FOR ALL NEARSHORE ZONES AS STRENGTHENING SW FLOW WILL LIKELY PRODUCE GUSTS TO 35 TO 40 KTS. SUNDAY AND SUNDAY NIGHT...SURFACE RIDGING...DRY AIR AND LOW LEVEL WAA WILL BRING AN END TO ALL REMAINING LAKE EFFECT PRECIP BY 12Z SUNDAY. DRY CONDITIONS WILL CONTINUE THRU SUNDAY NIGHT...WITH PARTIAL CLEARING EXPECTED. HIGH TEMPS SUNDAY AFTERNOON WILL WARM NICELY INTO THE UPPER 30S AND LOWER 40S COURTESY OF ONGOING WAA. LOW TEMPS SUNDAY NIGHT WILL COOL BACK INTO THE UPPER 20S AND LOWER 30S. MONDAY THROUGH WEDNESDAY...PAR FOR THE COURSE WHEN YOU HAVE SUCH ENERGETIC NORTHERN STREAM FLOW...WITH POSSIBLE INTERACTION WITH NORTHEAST EJECTING SOUTHERN STREAM WAVE...A CHALLENGING AND QUESTION RIDDLED FORECAST. EARLY MORNING NORTHERN HEMISPHERIC WATER VAPOR IMAGERY SHOWS PRIMARY PLAYERS OF INTEREST...ESPECIALLY EARLY ON IN THE EXTENDED...AS A SHARP NORTHERN STREAM WAVE DIVING SOUTH OVER THE NUNAVUT REGION OF CANADA AND DEVELOPING MID LEVEL LOW PRESSURE JUST SOUTH OF THE ARIZONA/MEXICO BORDER. 00Z MODEL SUITE IN DECENT AGREEMENT SHOWING SOUTHERN SYSTEM MOVING NORTHEAST INTO THE LOWER MISSISSIPPI VALLEY BY MONDAY MORNING AS AFOREMENTIONED NORTHERN STREAM WAVE DIVES INTO SOUTH CENTRAL CANADA. MODELS ALSO SHOW ENOUGH TEMPORAL AND SPATIAL SEPARATION OF THESE SYSTEMS TO PREVENT PHASING UNTIL WELL EAST OF THE REGION...THUS FAVORING A FARTHER SOUTH TRAJECTORY OF THE SOUTHERN LOW UP THROUGH THE OHIO VALLEY ON MONDAY. THIS FAVORS CURRENT CHANCE POPS IN FAR SOUTHERN ZONES MONDAY AFTERNOON. CONFIDENCE QUICKLY GOES DOWNHILL BEYOND MONDAY... ESPECIALLY WITH AMPLITUDE OF NORTHERN WAVE...AND ASSOCIATED SURFACE FEATURES...AS IT CUTS ACROSS THE NORTHERN LAKES. LATEST ECMWF A LITTLE MORE AMBITIOUS IN THIS REGARD THAN OTHER GUIDANCE...SHOWING LOW PRESSURE DEVELOPING ALONG THE ARCTIC FRONT OVER WESTERN LAKE SUPERIOR MONDAY NIGHT WHICH GRADUALLY FILLS AS IT PIVOT SOUTHEAST. PROGRESSIVE PATTERN CONTINUES INTO THE MIDDLE OF THE WEEK WITH INTERMOUNTAIN TROUGH AMPLIFICATION LEADING TO SURFACE CYCLOGENESIS OVER THE HIGH PLAINS ON WEDNESDAY...WITH ITS SIGHTS SET ON THE NORTHERN LAKES FOR THURSDAY. EXACT TIMING...STRENGTH... AND PLACEMENT YET TO BE DETERMINED SO WILL MAINTAIN OVERALL FORECAST CONTINUITY...WITH THE EXCEPTION OF ADDING WELL AGREED UPON WAA LIGHT SNOW CHANCES OVER NORTHERN AREAS WEDNESDAY. MSB && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ015- 017-019. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ016. LM...GALE WARNING UNTIL 11 AM EST SUNDAY FOR LMZ323-341-342-344>346. LH...GALE WARNING UNTIL 11 AM EST SUNDAY FOR LHZ345>349. LS...GALE WARNING UNTIL 5 AM EST SUNDAY FOR LSZ321-322. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 338 PM CST SAT NOV 24 2007 .DISCUSSION... LOW CLOUDS HAVE JUST ABOUT CLEARED OUT OF CWA...AND FAIRLY DRY COLUMN SHOULD KEEP MOSTLY CLEAR SKIES OVERNIGHT. ONE POTENTIAL PROBLEM IS IF LOW LEVEL WINDS BACK ENOUGH TO SEND SOME OF THE LOW CLOUDS OVER IA INTO SOUTH CENTRAL MN OVERNIGHT. SREF AND RUC HINT AT THIS SOMEWHAT BUT WILL ONLY INCREASE SKY GRID LEVELS A SMALL AMOUNT. STILL LOOKS LIKE A MILD AFTERNOOON OVER MOST OF THE AREA ON SUNDAY. MIXING FROM AROUND 900 MB ON WRF-NAM YIELDS NEAR 50 OVER PART OF SW MN. GFS SOMEWHAT LESS BUT WILL KEEP TEMPS CLOSE TO CURRENT FORECAST. HIGH CLOUDS WILL INCREASE SOME FROM NORTH TO SOUTH AS UPPER JET SAGS SOUTH...WHICH SHOULD LIMIT HIGHS IN CENTRAL MN. SOME DIFFERENCES IN SPEED OF COLD FRONT MOVING DOWN ON TUESDAY WITH NAM SLOWEST. WILL GO MORE ALONG WITH GFS/ECMWF WITH OUR AREA BEING MORE UNDER THE INFLUENCE OF THE NORTHERN BRANCH OF THE PATTERN LATELY. CHANCES FOR SNOW STILL A QUESTION. HAS NOT BEEN MUCH TENDENCY IN THE MODELS TO MERGE THE THE NORTHERN AND SOUTHERN STREAM...SO A SIGNIFICANT SNOW DOES NOT SEEM TO BE IN THE CARDS. GFS ENSEMBLE POP TRENDS SEEM TO BE FAVORING EAST CENTRAL MN ON INTO NORTHERN OR WEST CENTRAL WISCONSIN. ALTHOUGH..GFS HINTING AT SOME FRONTOGENESIS ON WED OVER SOUTHEAST MINNESOTA. WILL MAINTAIN THE HIGHER POPS ON WEDNESDAY. TRENDS TO COLDER AND BELOW NORMAL TEMPS FORECAST BY VARIOUS MODELS FOR END OF WEEK. SHOULD BE SOME SINGLE DIGIT LOWS AT LEAST IN CENTRAL MN...AND IF WE DO GET SOME SNOW COVER...THEN A REVISION DOWNWARD WOULD BE IN ORDER...POSSIBLY BELOW ZERO. LOOKING LIKE A TREND TOWARD A COLD HUDSON BAY UPPER LOW. && .AVIATION... /18Z TAF ISSUANCE/ BANK OF MVFR CIGS GRADUALLY LIFTING/MOVING EAST/NORTHEAST THIS MORNING. SHOULD SEE VFR AT ALL TAF SITE BY 19-20Z. THEN EXPECT STRATOCUMULUS TO MOVE EAST OUT OF WI AREA BY 22Z. JUST SOME HIGH CLOUDS ANTICIPATED FOR THE REMAINDER OF THE TAF PERIOD. W-SW WINDS WILL BE GUSTY THIS AFTERNOON...THEN SLACK OFF AFTER 23Z. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JPR/DWE mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1120 AM CST SAT NOV 24 2007 .AVIATION... /18Z TAF ISSUANCE/ BANK OF MVFR CIGS GRADUALLY LIFTING/MOVING EAST/NORTHEAST THIS MORNING. SHOULD SEE VFR AT ALL TAF SITE BY 19-20Z. THEN EXPECT STRATOCUMULUS TO MOVE EAST OUT OF WI AREA BY 22Z. JUST SOME HIGH CLOUDS ANTICIPATED FOR THE REMAINDER OF THE TAF PERIOD. W-SW WINDS WILL BE GUSTY THIS AFTERNOON...THEN SLACK OFF AFTER 23Z. && .PREV DISCUSSION... /ISSUED 412 AM CST SAT NOV 24 2007/ THE MAIN FORECAST CONCERNS ARE CLOUD COVER TODAY AND SNOW CHANCES DURING THE EARLY/MIDDLE PORTIONS OF NEXT WEEK. 0930Z SAT WATER VAPOR IMAGERY SHOWS THE MID LEVEL TROUGH AXIS PUSHING ACROSS MN. ATTENDANT STRATUS DECK...WHICH MODELS HAVE A VERY POOR HANDLE ON...EXTENDS FROM CENTRAL MN BACK TOWARD THE CENTRAL DAKOTAS. SNOW SHOWERS CORRELATE WITH THE 20-25 DBZ ECHOES ON THE MPX RADAR...AND RUC/NAM/GFS PROGGED LIFT BETWEEN 850-700MB. WHILE THIS WEAKENS SOMEWHAT THIS MORNING...SCATTERED FLURRIES ARE STILL EXPECTED THIS MORNING...ESPECIALLY ACROSS EAST CENTRAL MN AND WEST CENTRAL WI. AS MENTIONED BEFORE...NO MODEL IS CAPTURING THE LOW LEVEL MOISTURE PROFILES ADEQUATELY THIS MORNING. MORE SPECIFICALLY...THE 00Z/24 GFS PROGGED 925MB LEVEL RH VALUES OF 45 PERCENT ACROSS EASTERN NORTH DAKOTA AT 06Z...WHERE AN OVERCAST DECK CIRCA 3K FEET WAS REALIZED. ALTHOUGH THE RH PROG WAS TOO DRY...THE 11-3.9 MICRON CHANNEL ON SATELLITE WAS BEGINNING TO SHOW THE DEVELOPMENT OF A DRY WEDGE EXPANDING INTO EASTERN NORTH DAKOTA. THEREFORE...THINK THAT THE GFS MAY BE ONTO SOMETHING...AND MAY SEE MORE CLEARING OCCURRING AHEAD OF THE BACK EDGE AS SUBSIDENCE OCCURS IN THE WAKE OF THE SHORTWAVE TROUGH. HAVE STILL GONE MORE PESSIMISTIC ON THE SKY COVER FOR TODAY...WITH CLOUDY TO MOSTLY CLOUDY CONDITIONS UNTIL THIS AFTERNOON. DUE TO THE CLOUD COVER CONCERNS...AND PERSISTENCE OVER THE LAST SEVERAL DAYS...HAVE ALSO UNDERCUT NUMERICAL GUIDANCE FOR TODAY...WITH HIGHS IN THE MID/UPPER 30S EXPECTED. IN THE WAKE OF THE TROUGH...WESTERLY/ZONAL FLOW DEVELOPS OVER THE REMAINDER OF THE WEEKEND. 925MB TEMPERATURES MODERATE TO +4 CELSIUS ACROSS MUCH OF THE CENTRAL/SOUTHWEST ON SUNDAY AFTERNOON. ANTICIPATE MOST OF THE CWA TO WARM IN THE MID/UPPER 40S ON SUNDAY...WITH BREEZY SOUTHWEST WINDS AND MOSTLY CLEAR SKIES YIELDING DECENT MIXING POTENTIAL. A FEW 50 DEGREE READINGS ARE NOT OUT OF THE QUESTION. BOTH GFS/ECMWF MODELS FEATURE A SHORTWAVE DIPPING DOWN FROM CANADA INTO THE NORTH CENTRAL CONUS ON TUESDAY/WEDNESDAY. WHILE THE AGREEMENT ON THE SURFACE TRACK/STRENGTH IS STILL UNCERTAIN...THE MAJORITY OF MEDIUM RANGE MODEL SOLUTIONS ARE INDICATIVE/SUPPORTIVE OF 30 POPS FOR SNOW FROM LATE TUESDAY THROUGH WEDNESDAY. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1134 AM CST SAT NOV 24 2007 .AVIATION... 18Z TAF DISCUSSION LARGE AREA OF RAIN CONTINUES TO MOVE ACROSS THE EASTERN HALF OF THE STATE WITH THE HEAVIEST RAIN NOW LOCATED ACROSS SOUTHEAST AND EAST TEXAS. RADAR SHOWS THE RAIN BEGINNING TO THIN OUT ACROSS THE WESTERN HALF OF NORTH TEXAS BUT STILL EXPECT PERIODS OF ON-AND-OFF LIGHT RAIN THROUGH MID AFTERNOON. SHOULD THEN SEE A BREAK IN THE PRECIPITATION FROM MID AFTERNOON INTO THE NIGHT BEFORE PRECIPITATION STARTS UP AGAIN AROUND 04Z. THIS NEW WAVE OF PRECIPITATION SHOULD AGAIN BE MAINLY LIGHT RAIN AND IS EXPECTED TO CONTINUE THROUGH THE END OF THE TAF PERIOD...BUT SHOULD BE SHIFTING TO THE EAST AND ENDING AROUND 18Z SUNDAY. HAVE INCLUDED TEMPO GROUP FOR LIGHT SNOW BASED ON LATEST ACARS SOUNDINGS AND MODEL DATA WHICH SHOW THE ATMOSPHERE ABOVE THE SURFACE RAPIDLY COOLING TO NEAR AND BELOW FREEZING VALUES. HOWEVER...WITH SURFACE TEMPERATURES REMAINING SEVERAL DEGREES ABOVE FREEZING...EXPECT SNOW TO MELT ON IMPACT AND NOT CREATE ANY HAZARDS AT THE SURFACE. CEILINGS CURRENTLY REMAIN IN MVFR CATEGORY WITH A FEW IFR SPOTS. EXPECT ALL LOCATIONS TO LOWER INTO IFR CONDITIONS EARLY THIS AFTERNOON AND REMAIN THERE THROUGH THE END OF THE PERIOD. WILL KEEP AN EYE OUT FOR LIFR CONDITIONS WHICH ARE A SLIGHT POSSIBILITY...ESPECIALLY AT KACT 82/JLD && .PREV DISCUSSION... /ISSUED 1045 AM CST SAT NOV 24 2007/ UPDATE... LIGHT TO MODERATE RAIN CONTINUES TO FALL ACROSS NORTH TEXAS THIS MORNING. WE ARE SEEING A MIX OF LIGHT RAIN/SLEET/SNOW ACROSS THE NORTHWEST ZONES AS EXPECTED. WE ARE GETTING A LITTLE CONCERNED WITH THE LOSS OF THE WARM NOSE OVER THE CENTRAL ZONES AS INDICATED ON THE LATEST ACARS SOUNDING NEAR DFW AIRPORT. WE COULD SEE A MIX OF RAIN AND SNOW NEAR THE INTERSTATE 35 CORRIDOR AND EVEN SLIGHTLY FURTHER EAST IN THE NEXT COUPLE OF HOURS. WE WILL BE SENDING UP AN 18Z SOUNDING TO ASSESS THE TEMPERATURE PROFILE. THE GOOD NEWS IS THAT SURFACE TEMPS WILL REMAIN WELL ABOVE FREEZING SO NO ACCUMULATIONS OR TRAVEL PROBLEMS ARE ANTICIPATED. FOR THIS UPDATE WE WILL ADD THE MENTION OF A WINTRY MIX A LITTLE FURTHER EAST THAN THE PREVIOUS FORECAST PACKAGE. WILL ALSO ADJUST HOURLY TEMPS/DEWPOINTS SLIGHTLY. AVIATION... 534 AM ALL NORTH TEXAS TERMINALS WILL TREND INTO IFR CONDITIONS BY MIDDAY AND REMAIN FOR THE MOST IFR...POSSIBLE GOING LIFR...THROUGH 12Z SUNDAY. STRONG ISENTROPIC FORCING OVER MUCH OF CENTRAL AND NORTH TEXAS THIS MORNING WILL CONTINUE THROUGH TONIGHT. THE LOWER ATMOSPHERE WILL MOISTEN UP WITH TIME...LOWERING CIGS THROUGH MVFR TO IFR AROUND MIDDAY. AS THE PRECIPITATION GEARS UP LATER TODAY...CIGS AND VIS WILL FALL...AND SOMETIMES GO LIFR DURING THE AFTERNOON OR DEFINITELY THIS EVENING AND OVERNIGHT. FLIGHTS TO SOUTHWEST TEXAS...WEST TEXAS AND WESTERN OKLAHOMA WILL FIND IFR CIGS/VIS AND SNOW OR SLEET MIXED WITH RAIN TODAY TRANSITIONING TO MAINLY SNOW TONIGHT. AREAS NORTH THROUGH EAST AND SOUTH OF NORTH TEXAS WILL BE SIMILAR TO TAF CONDITIONS OF KACT OR KDFW. PREV DISCUSSION... 452 AM CST. COMPLEX FORECAST...AS IS USUALLY THE CASE WHEN DEALING WITH POSSIBLE WINTER WEATHER IN TEXAS. OVERNIGHT MODEL FORECASTS HAVE TRENDED A LITTLE COOLER...AND LATEST RUC FORECASTS AND ACARS DATA SHOW TEMPS RIGHT AT FREEZING FROM 900 TO 700 MB OVER DFW...WITH A GRADUAL WARM-UP OCCURRING NEAR 850 MB DUE TO SOUTHERLY FLOW. MODELS ARE UNANIMOUS THAT AN 850 MB INVERTED TROUGH WILL DEVELOP TODAY AND BISECT THE CWA. ON THE SOUTHERN/WARM SIDE...TREMENDOUS WARM THERMAL/MOISTURE ADVECTION WILL OCCUR AS FLOW STRENGTHENS TO 40KT. THIS AIR WILL BE FORCED UP AND OVER THE COLD LAYER AT THE SURFACE AND ALLOW FOR WIDESPREAD RAIN AND ISOLATED THUNDERSTORMS. SOME OF THE RAIN WILL BE HEAVY IN THE SE ZONES THIS MORNING WHERE OVER AN INCH OR TWO IS POSSIBLE TODAY. ON THE NORTHERN/COLD SIDE OF THE 850 TROUGH...WINDS WILL BACK TO THE NORTHEAST AND KEEP LOW- MID LEVEL TEMPS MUCH COOLER AND FLIRTING WITH FREEZING. A WINTRY MIX IS POSSIBLE TODAY GENERALLY NW OF A SHERMAN TO EASTLAND LINE. SURFACE TEMPERATURES WILL BE IN THE MID-UPPER 30S AND NO SNOW/ICE ACCUMULATIONS THROUGH EARLY THIS EVENING ARE EXPECTED. MODELS SUGGEST AN ABOVE FREEZING LAYER /OR WARM NOSE/ WILL DEVELOP AND ENCOMPASS ALL OF THE NORTHWESTERN ZONES TONIGHT. MEANWHILE AFTER A BRIEF RESPITE THIS AFTERNOON FROM THE WIDESPREAD RAIN... ANOTHER ROUND OF SIGNIFICANT PRECIPITATION WILL BE DEVELOPING AHEAD OF THE UPPER LEVEL LOW AFTER SUNSET. THIS PRECIPITATION WILL BE ALL SNOW IN THE CLOUDS...BUT WILL HAVE TROUBLE REACHING THE SURFACE DUE TO THE LAYER OF ABOVE FREEZING TEMPS. HOWEVER... THE MELTING OF FROZEN HYDROMETEORS OVER TIME WILL FORCE THE TEMPERATURE TO FREEZING AS LATENT HEAT IS ABSORBED. THIS IS LIKELY TO HAPPEN UNDER BANDS OF INTENSE PRECIPITATION...WHICH THE MODELS DO INDICATE OVER THE NW HALF OF THE CWA TONIGHT. MODEL SOUNDINGS AND PARTIAL THICKNESS ANALYSIS SHOWS A RAIN/SNOW MIX NW OF A COMANCHE TO BOWIE LINE TONIGHT. HEAVY BURSTS OF SNOW COULD OCCUR AND THIS WOULD RESULT IN A QUICK ACCUMULATION OF SNOW ON THE GROUND. THEREFORE...WE HAVE ISSUED A WINTER WEATHER ADVISORY FROM 9 PM TO 9 AM FOR THE NW COUNTIES AS TRAVEL COULD BE IMPACTED FOR A FEW HOURS. GROUND TEMPS ARE WARM AND COLD ADVECTION IS LACKING SO WOULD EXPECT ANY ACCUMULATION TO GRADUALLY MELT AWAY SUNDAY. HAVE INCLUDED LIGHT SNOW AND FLURRIES IN THE CENTRAL ZONES EARLY SUNDAY AS THERE COULD BE A FEW SNOWFLAKES THAT SURVIVE THE TRIP DOWN...BUT WARM LAYER SHOULD BE MORE STOUT. SURFACE TEMPS OVER THE CENTRAL ZONES SHOULD REMAIN ABOVE FREEZING WITH LITTLE IMPACT EXPECTED. AS THE UPPER LEVEL LOW MOVES INTO WEST CENTRAL TEXAS...MUCH OF THE CWA WILL GET DRY SLOTTED WITH SIGNIFICANT RAINS ENDING SUNDAY MORNING AND HAVE DIALED DOWN THE POPS SUNDAY AFTERNOON. GFS/ECMWF SHOW UPPER LEVEL LOW TRACKING RIGHT OVER NW ZONES SUNDAY EVENING AND WITH SUBSTANTIAL COOLING FORCED VIA DYNAMIC LIFTING...A CHANGE TO ALL SNOW IS POSSIBLE NW OF A SHERMAN TO EASTLAND LINE. THERE COULD BE SOME ACCUMULATIONS OF WRAPAROUND SNOW AS THE UPPER LOW EXITS. STILL 36-48 HOURS AWAY...SO WILL PLAY IT CONSERVATIVE. AFTER THE UPPER LOW EXITS WE WILL SEE A QUICK WARM UP WITH SW FLOW IN THE LOW LEVELS. ANOTHER FRONT IS EXPECTED WEDNESDAY WITH A SLIGHT CHANCE OF RAIN AND A COOL DOWN. LOW RAIN CHANCES WILL RETURN AT THE END OF THE WEEK AHEAD OF A PACIFIC UPPER LOW. TR.92 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 43 37 43 36 60 / 100 100 50 50 10 WACO, TX 44 38 45 38 60 / 100 100 50 20 10 PARIS, TX 43 37 43 37 55 / 100 100 80 60 10 DENTON, TX 42 36 42 35 60 / 100 100 50 50 10 MCKINNEY, TX 42 37 43 36 58 / 100 100 50 50 10 DALLAS, TX 43 37 43 37 59 / 100 100 50 50 10 TERRELL, TX 43 38 44 39 59 / 100 100 60 50 10 CORSICANA, TX 43 39 45 37 60 / 100 100 60 30 10 TEMPLE, TX 44 38 45 36 61 / 100 100 50 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST SUNDAY FOR THE FOLLOWING ZONES: TXZ091-100-101-115-116-129. && $$ 82/75 tx AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE FORT WORTH TX 1045 AM CST SAT NOV 24 2007 .UPDATE... LIGHT TO MODERATE RAIN CONTINUES TO FALL ACROSS NORTH TEXAS THIS MORNING. WE ARE SEEING A MIX OF LIGHT RAIN/SLEET/SNOW ACROSS THE NORTHWEST ZONES AS EXPECTED. WE ARE GETTING A LITTLE CONCERNED WITH THE LOSS OF THE WARM NOSE OVER THE CENTRAL ZONES AS INDICATED ON THE LATEST ACARS SOUNDING NEAR DFW AIRPORT. WE COULD SEE A MIX OF RAIN AND SNOW NEAR THE INTERSTATE 35 CORRIDOR AND EVEN SLIGHTLY FURTHER EAST IN THE NEXT COUPLE OF HOURS. WE WILL BE SENDING UP AN 18Z SOUNDING TO ASSESS THE TEMPERATURE PROFILE. THE GOOD NEWS IS THAT SURFACE TEMPS WILL REMAIN WELL ABOVE FREEZING SO NO ACCUMULATIONS OR TRAVEL PROBLEMS ARE ANTICIPATED. FOR THIS UPDATE WE WILL ADD THE MENTION OF A WINTRY MIX A LITTLE FURTHER EAST THAN THE PREVIOUS FORECAST PACKAGE. WILL ALSO ADJUST HOURLY TEMPS/DEWPOINTS SLIGHTLY. && .AVIATION... 534 AM ALL NORTH TEXAS TERMINALS WILL TREND INTO IFR CONDITIONS BY MIDDAY AND REMAIN FOR THE MOST IFR...POSSIBLE GOING LIFR...THROUGH 12Z SUNDAY. STRONG ISENTROPIC FORCING OVER MUCH OF CENTRAL AND NORTH TEXAS THIS MORNING WILL CONTINUE THROUGH TONIGHT. THE LOWER ATMOSPHERE WILL MOISTEN UP WITH TIME...LOWERING CIGS THROUGH MVFR TO IFR AROUND MIDDAY. AS THE PRECIPITATION GEARS UP LATER TODAY...CIGS AND VIS WILL FALL...AND SOMETIMES GO LIFR DURING THE AFTERNOON OR DEFINITELY THIS EVENING AND OVERNIGHT. FLIGHTS TO SOUTHWEST TEXAS...WEST TEXAS AND WESTERN OKLAHOMA WILL FIND IFR CIGS/VIS AND SNOW OR SLEET MIXED WITH RAIN TODAY TRANSITIONING TO MAINLY SNOW TONIGHT. AREAS NORTH THROUGH EAST AND SOUTH OF NORTH TEXAS WILL BE SIMILAR TO TAF CONDITIONS OF KACT OR KDFW. && PREV DISCUSSION... 452 AM CST. COMPLEX FORECAST...AS IS USUALLY THE CASE WHEN DEALING WITH POSSIBLE WINTER WEATHER IN TEXAS. OVERNIGHT MODEL FORECASTS HAVE TRENDED A LITTLE COOLER...AND LATEST RUC FORECASTS AND ACARS DATA SHOW TEMPS RIGHT AT FREEZING FROM 900 TO 700 MB OVER DFW...WITH A GRADUAL WARM-UP OCCURRING NEAR 850 MB DUE TO SOUTHERLY FLOW. MODELS ARE UNANIMOUS THAT AN 850 MB INVERTED TROUGH WILL DEVELOP TODAY AND BISECT THE CWA. ON THE SOUTHERN/WARM SIDE...TREMENDOUS WARM THERMAL/MOISTURE ADVECTION WILL OCCUR AS FLOW STRENGTHENS TO 40KT. THIS AIR WILL BE FORCED UP AND OVER THE COLD LAYER AT THE SURFACE AND ALLOW FOR WIDESPREAD RAIN AND ISOLATED THUNDERSTORMS. SOME OF THE RAIN WILL BE HEAVY IN THE SE ZONES THIS MORNING WHERE OVER AN INCH OR TWO IS POSSIBLE TODAY. ON THE NORTHERN/COLD SIDE OF THE 850 TROUGH...WINDS WILL BACK TO THE NORTHEAST AND KEEP LOW- MID LEVEL TEMPS MUCH COOLER AND FLIRTING WITH FREEZING. A WINTRY MIX IS POSSIBLE TODAY GENERALLY NW OF A SHERMAN TO EASTLAND LINE. SURFACE TEMPERATURES WILL BE IN THE MID-UPPER 30S AND NO SNOW/ICE ACCUMULATIONS THROUGH EARLY THIS EVENING ARE EXPECTED. MODELS SUGGEST AN ABOVE FREEZING LAYER /OR WARM NOSE/ WILL DEVELOP AND ENCOMPASS ALL OF THE NORTHWESTERN ZONES TONIGHT. MEANWHILE AFTER A BRIEF RESPITE THIS AFTERNOON FROM THE WIDESPREAD RAIN... ANOTHER ROUND OF SIGNIFICANT PRECIPITATION WILL BE DEVELOPING AHEAD OF THE UPPER LEVEL LOW AFTER SUNSET. THIS PRECIPITATION WILL BE ALL SNOW IN THE CLOUDS...BUT WILL HAVE TROUBLE REACHING THE SURFACE DUE TO THE LAYER OF ABOVE FREEZING TEMPS. HOWEVER... THE MELTING OF FROZEN HYDROMETEORS OVER TIME WILL FORCE THE TEMPERATURE TO FREEZING AS LATENT HEAT IS ABSORBED. THIS IS LIKELY TO HAPPEN UNDER BANDS OF INTENSE PRECIPITATION...WHICH THE MODELS DO INDICATE OVER THE NW HALF OF THE CWA TONIGHT. MODEL SOUNDINGS AND PARTIAL THICKNESS ANALYSIS SHOWS A RAIN/SNOW MIX NW OF A COMANCHE TO BOWIE LINE TONIGHT. HEAVY BURSTS OF SNOW COULD OCCUR AND THIS WOULD RESULT IN A QUICK ACCUMULATION OF SNOW ON THE GROUND. THEREFORE...WE HAVE ISSUED A WINTER WEATHER ADVISORY FROM 9 PM TO 9 AM FOR THE NW COUNTIES AS TRAVEL COULD BE IMPACTED FOR A FEW HOURS. GROUND TEMPS ARE WARM AND COLD ADVECTION IS LACKING SO WOULD EXPECT ANY ACCUMULATION TO GRADUALLY MELT AWAY SUNDAY. HAVE INCLUDED LIGHT SNOW AND FLURRIES IN THE CENTRAL ZONES EARLY SUNDAY AS THERE COULD BE A FEW SNOWFLAKES THAT SURVIVE THE TRIP DOWN...BUT WARM LAYER SHOULD BE MORE STOUT. SURFACE TEMPS OVER THE CENTRAL ZONES SHOULD REMAIN ABOVE FREEZING WITH LITTLE IMPACT EXPECTED. AS THE UPPER LEVEL LOW MOVES INTO WEST CENTRAL TEXAS...MUCH OF THE CWA WILL GET DRY SLOTTED WITH SIGNIFICANT RAINS ENDING SUNDAY MORNING AND HAVE DIALED DOWN THE POPS SUNDAY AFTERNOON. GFS/ECMWF SHOW UPPER LEVEL LOW TRACKING RIGHT OVER NW ZONES SUNDAY EVENING AND WITH SUBSTANTIAL COOLING FORCED VIA DYNAMIC LIFTING...A CHANGE TO ALL SNOW IS POSSIBLE NW OF A SHERMAN TO EASTLAND LINE. THERE COULD BE SOME ACCUMULATIONS OF WRAPAROUND SNOW AS THE UPPER LOW EXITS. STILL 36-48 HOURS AWAY...SO WILL PLAY IT CONSERVATIVE. AFTER THE UPPER LOW EXITS WE WILL SEE A QUICK WARM UP WITH SW FLOW IN THE LOW LEVELS. ANOTHER FRONT IS EXPECTED WEDNESDAY WITH A SLIGHT CHANCE OF RAIN AND A COOL DOWN. LOW RAIN CHANCES WILL RETURN AT THE END OF THE WEEK AHEAD OF A PACIFIC UPPER LOW. TR.92 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 43 37 43 36 60 / 100 100 50 50 10 WACO, TX 44 38 45 38 60 / 100 100 50 20 10 PARIS, TX 43 37 43 37 55 / 100 100 80 60 10 DENTON, TX 42 36 42 35 60 / 100 100 50 50 10 MCKINNEY, TX 42 37 43 36 58 / 100 100 50 50 10 DALLAS, TX 43 37 43 37 59 / 100 100 50 50 10 TERRELL, TX 43 38 44 39 59 / 100 100 60 50 10 CORSICANA, TX 43 39 45 37 60 / 100 100 60 30 10 TEMPLE, TX 44 38 45 36 61 / 100 100 50 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST SUNDAY FOR THE FOLLOWING ZONES: TXZ091-100-101-115-116-129. && $$ 92/75 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 259 PM CST SAT NOV 24 2007 .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT MAIN FORECAST CONCERNS ARE ON CLOUDS AND TEMPERATURES THROUGH THE PERIOD. 18Z SURFACE ANALYSIS SHOWS HIGH PRESSURE OVER THE OHIO VALLEY WITH SOUTHWESTERLY LOW LEVEL WINDS FROM KANSAS INTO WISCONSIN ON ITS BACK SIDE. VISIBLE SATELLITE IMAGERY SHOWING STRATUS FIELD OVER THE REMAINING SNOWPACK IN NORTHEAST MISSOURI AND SOUTHWEST IOWA. SATELLITE LOOP SHOWS THESE CLOUDS WORKING NORTHEAST ON THE SOUTHWEST LOW LEVEL WIND...BUT HAVE BEEN ERODING ON THEIR NORTHERN EDGE AS THEY APPROACH NORTHEAST IOWA. FARTHER NORTH...MORE STRATO-CUMULUS HAD DEVELOPED OVER THE PAST HOUR ACROSS SOUTHEAST MINNESOTA WITH ITS BACK EDGE PUSHING STEADILY EASTWARD. 12Z NAM/WRF AND GFS IN DECENT AGREEMENT THROUGH 72 HOURS AFTER WHICH DIFFERENCES APPEAR WITH RESPECT TO THE 500MB HEIGHT FIELDS AND SURFACE PRESSURE FIELDS OVER THE PLAINS AS TROUGHING DEVELOPS ACROSS THE WEST. IN THE NEAR TERM...BIGGEST QUESTION WILL BE ON NORTHEAST EXTENT OF STRATUS FIELD ACROSS IOWA. BOTH THE NAM12 AND RUC 925MB RELATIVE HUMIDITY FIELDS SHOWS THIS AREA CONTINUING TO ADVECT NORTHEASTWARD ACROSS THE REMAINING SNOWFIELD INTO SOUTHWEST WISCONSIN TONIGHT. WITH SATELLITE TRENDS OF EROSION ON THE NORTH SIDE HAVE OPTED FOR PARTLY CLOUDY SKIES TONIGHT ACROSS THE SOUTH. FARTHER NORTH THE BACK EDGE OF THE STRATO CUMULUS DECK NOW WORKING ITS WAY INTO SOUTHEAST MINNESOTA AND MODELS CONTINUE THIS WESTWARD TREND THIS EVENING. WITH GRADIENT REMAINING TIGHT TONIGHT WILL KEEP WIND SPEEDS UP A LITTLE AND THIS COMBINED WITH THE LOW LEVEL WARM ADVECTION WILL HELP TEMPERATURES FROM BOTTOMING OUT AND DID GO A LITTLE ABOVE GUIDANCE FOR LOWS. WARM ADVECTION CONTINUES THROUGH SUNDAY AHEAD OF THE NEXT APPROACHING SHORTWAVE/SURFACE TROUGH. 850MB TEMPERATURES WARM TO AROUND +2 CELSIUS. ATMOSPHERE TO REMAIN RELATIVELY DRY AND WITH THE CONTINUED SOUTHWEST WINDS HAVE RAISED TEMPERATURES A FEW DEGREES FROM THE PREVIOUS FORECAST. SHORTWAVE/SURFACE TROUGH PASS THROUGH THE AREA SUNDAY NIGHT WITH ONLY SOME WEAK 850-700MB QG CONVERGENCE. WITH THIS LACK OF MOISTURE AND WEAK FORCING EXPECT A DRY PASSAGE WITH ONLY PERHAPS A FEW HIGH CLOUDS. COLD ADVECTION BEHIND THE DEPARTING WAVE WILL DROP TEMPERATURES BACK TO NEAR NORMAL BY MONDAY. THE QUIET WEATHER PATTERN WILL CONTINUE THROUGH TUESDAY NIGHT WITH SEASONABLE TEMPERATURES. .LONG TERM...WEDNESDAY THROUGH SATURDAY THE MEDIUM RANGE MODELS CONTINUE TO SHOW QUITE A BIT OF VARIABILITY IN THEIR SOLUTIONS...ESPECIALLY FOR THE SYSTEM ON WEDNESDAY. DETERMINISTIC MODELS HAVING TROUBLE IN HANDLING THE NORTHERN AND SOUTHERN STREAM ENERGY ON DAY 4(WEDNESDAY). ECMWF...WHICH WAS THE FAR NORTHERN SOLUTION YESTERDAY IS NOW THE MORE SOUTHERN WITH ITS 00Z RUN. DPROG/DT OF BOTH THE GFS AND ECMWF SHOW A BIT MORE CONSISTENCY WITH THE LAST 3 RUNS OF THE ECMWF AND PER NCEP DISCUSSION THE 00Z ECMWF HAS BETTER SUPPORT FROM THE OTHER GLOBAL MODELS. WITH THIS UNCERTAINTY DID NOT MAKE A LOT OF CHANGES TO THE GRIDDED DATABASE. DID ADD THE MENTION OF RAIN OR SNOW TO THE SOUTHERN END OF THE FORECAST AREA ON WEDNESDAY. COOLER AIR FILTER IN BEHIND THE DEPARTING SYSTEM FOR THURSDAY THROUGH SATURDAY. WITH CYCLONIC FLOW OVER THE AREA THURSDAY FOR MOSTLY CLOUDY SKIES... OTHERWISE DRY AND COLD EXPECTED THURSDAY NIGHT THROUGH SATURDAY. && .AVIATION...TODAY AND TONIGHT A MILDER SOUTHWEST SURFACE FLOW BLOWING ACROSS A MELTING SNOWPACK ACROSS IA INTO SOUTHWEST WI WILL ADVECT A FEW STRATOCUMULUS IN THE 3000-4000 FT RANGE INTO THE REGION THIS AFTERNOON INTO TONIGHT. THIS WILL OCCUR MAINLY ACROSS FAR NORTHEAST WI INTO FAR SOUTHWEST WI...CLOSER TO THE SNOWPACK. KRST SHOULD REMAIN FAR ENOUGH NORTH OF THIS CLOUD ADVECTION. HOWEVER...KLSE MAY SEE A FEW STRATOCUMULUS FROM TIME TO TIME. HAVE ADDED THIS IN THE KLSE TAF SITE. OTHERWISE...SOUTHWEST SURFACE FLOW WILL CONTINUE THROUGH SUNDAY AS LOW PRESSURE TRACKS ALONG THE U.S./CANADIAN BORDER. ONLY A FEW CIRRUS CLOUDS ARE EXPECTED ACROSS THE KLSE/KRST TAF SITES SUNDAY MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT AND LONG TERM - JLR AVIATION - DAS wi