AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL ISSUED BY NWS JACKSONVILLE FL 340 PM EST WED FEB 27 2002 FORECAST CHALLENGE -- PRECIPITATION THIS WEEKEND. --SYNOPSIS-- WATER VAPOR IMAGES SHOW INTENSE UPPER JET EXITING THE E COAST AS IT BEGINS TO LIFT OUT OF THE BASE OF THE DEEP UPPER TROUGH OVER THE ERN USA. REINFORCING VORT MAXIMA CAN BE SEEN UPSTREAM OVER THE SRN PLAINS AND THE PACIFIC NW. SURFACE HIGH IS CURRENTLY CENTERED NEAR THE LA/AR BORDER WITH BRISK NW FLOW CONTINUING OVER THE CWFA. AIR IS EXTREMELY DRY WITH DEWPOINTS IN THE SINGLE DIGITS (F). BEST THETA-E PACKING CONTINUES OVER OUR COASTAL WATERS AND MOST OF THE FL PENINSULA. --FORECAST-- TONIGHT...WINDS SHOULD QUICKLY DECREASE AS SURFACE HIGH ENTERS OUR WRN CWFA. HAVE ALREADY ISSUED A HARD FREEZE AREAWIDE TONIGHT FOR EXPECTED RECORD LOW TEMPERATURES. SOME CURRENTLY EXISTING RECORD LOWS FOR 2/28: TALLAHASSEE RECORD LOW: 24 SET IN 1935 APALACHICOLA RECORD LOW: 27 SET IN 1935 THURSDAY...SHOULD BE DRY WITH VARIABLE WINDS AS SURFACE HIGH CENTER PASSES E OVER THE CWFA. THURSDAY NIGHT...APPEARS THAT MANY AREAS COULD SEE A SIGNIFICANT FREEZE AGAIN AS SURFACE HIGH CENTER AND ASSOCIATED DRY AIR LIFT SLOWLY NE OUT OF OUR CWFA. FRIDAY...AS SURFACE LOW INTENSIFIES TO OUR W...CLOUDS SHOULD INCREASE. WILL PUT IN LATE DAY 20% POPS TO ACCOUNT FOR POSSIBILITY OF ISENTROPIC PRECIPITATION. FRIDAY NIGHT...MINIMUM TEMPERATURE SHOULD BE SIGNIFICANTLY WARMER AS CLOUDS INCREASE. POPS WILL ALSO BEGIN IN EARNEST FOR OUR WRN ZONES AT THIS TIME WITH THE APPROACHING LOW FIRE WEATHER - HAVE EXPANDED RED FLAG WARNING THURSDAY TO INCLUDE ALL FL ZONES. NO OTHER CHANGES. MARINE - WINDS AND SEAS STILL MEETING SCA OVER COASTAL WATERS. 18Z RUC CONTINUES TO ADVERTISE A DRASTIC DECREASE IN WINDS THROUGH 06Z TONIGHT. WILL KEEP SCA HIGHLIGHTS UP...BUT EVENING SHIFT WILL PROBABLY BE ABLE TO DROP THEM IN THEIR UPDATE. HAVE KEPT WINDS FAIRLY HIGH IN EXTENDED WITH NEXT FROPA (SEE BELOW). EXTENDED (SATURDAY THROUGH WEDNESDAY) - 27/00Z MRF PUTS PREFRONTAL TROUGH LINE WITH PRECIPITATION IN OUR WRN ZONES SATURDAY MORNING AND TRANSLATES IT TO OUR ERN ZONES SATURDAY EVENING. NOGAPS 27/00Z AND 27/12Z RUNS ARE A LITTLE SLOWER WITH ENTRANCE OF PRECIPITATION AND LATER WITH EXIT. ACTUAL COLD FRONT SHOULD CLEAR OUR SERN CWFA BY SUNDAY MORNING. ASSOCIATED 1030+ MB SURFACE HIGH TO THEN TRANSLATE E TOWARDS OUR CWFA THROUGH TUESDAY. THIS OVERALL PATTERN LOOKS VERY SIMILAR TO WHAT WE ARE NOW EXPERIENCING...ALBEIT ON A SLIGHTLY LESS INTENSE SCALE. 27/00Z MEX GUIDANCE SUGGESTS FREEZING TEMPERATURES WILL AGAIN BE POSSIBLE OVER INTERIOR PARTS OF OUR CWFA MONDAY MORNING WHEN THE SURFACE HIGH IS JUST W OUR CWFA (JUST LIKE OUR CURRENT SURFACE HIGH WILL BE TOMORROW MORNING). PRELIMINARY NUMBERS... TLH 017/054 026/065 0000 PFN 024/054 035/065 0002 DHN 019/052 030/061 0001 ABY 017/052 026/030 000- VLD 020/054 028/030 0000 .TLH... .AL...HARD FREEZE WARNING TONIGHT ALL ZONES. .GA...HARD FREEZE WARNING TONIGHT ALL ZONES. .FL...SMALL CRAFT ADVISORY THROUGH EARLY TONIGHT ALL MARINE ZONES. RED FLAG WARNING LATE THIS AFTERNOON ALL ZONES. HARD FREEZE WARNING TONIGHT ALL ZONES. RED FLAG WARNING THURSDAY AFTERNOON ALL ZONES. NOTE: THE NATIONAL WEATHER SERVICE OFFICE IN TALLAHASSEE IS CURRENTLY MOVING TO A NEW LOCATION ON THE CAMPUS OF FLORIDA STATE UNIVERSITY. FORECASTS FROM MONDAY THE 25TH THROUGH FRIDAY MARCH 1ST ARE BEING ISSUED FROM THE NATIONAL WEATHER SERVICE OFFICE IN JACKSONVILLE FLORIDA. DURING THIS PERIOD, TALLAHASSEE FORECASTERS CAN BE REACHED IN JACKSONVILLE AT 904-741-5186. ADMINISTRATIVE PERSONNEL IN TALLAHASSEE MAY BE REACHED DURING NORMAL BUSINESS HOURS VIA OUR NEW PUBLIC TELEPHONE NUMBER 850-942-8833 STARTING MONDAY. SEE THE LATEST MIAPNSTLH (WMO HEADER NOUS42 KTAE) FOR ADDITIONAL DETAILS ABOUT THE MOVE. TJT fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 836 AM EST WED FEB 27 2002 UPDATED NORTHERN GROUPS SNOW ACCUMULATION FROM NO ACCUMULATION TO AN INCH OR LESS. UPDATED WINDS IN ALL GROUPS TO 10 TO 15 MPH. PREVIOUS DISCUSSION FOLLOWS. OUDEMAN MAJOR FORECAST PROBLEM TODAY IS THE FRIDAY THROUGH SUNDAY PERIOD. IN THE NEAR TERM HAVE OPTED TO STAY CLOSE TO GOING FORECAST. THE MODELS ARE ALL ALIGNED WELL...WITH SUBTLE TIMING DIFFERENCES. BANDED SNOW SHOWERS HAVE BEEN ONGOING OVERNIGHT AND EXPECT THAT THESE WILL CONTINUE THROUGH THE DAY AS WE CONTINUE TO BE IN CYCLONIC UPSLOPE FLOW. MOST OF THE UPPER LEVEL DYNAMICS HAVE SLIPPED OFF TO THE EAST AND DO NOT EXPECT WIDESPREAD SNOW ACCUMULATION. TEMPERATURES TONIGHT STILL A CHALLENGE AND HAVE OPTED TO STAY WITH MAV DATA. WE DO NOT HAVE A LOT OF SNOW AND EXPECT THAT THE CLOUDS WILL LINGER ENOUGH TO PREVENT SIGNIFICANT RADIATIONAL COOLING. WILL CONSIDER PUTTING IN A LOCAL EFFECT...BUT NOT SURE THAT WE WILL HAVE THE MIXING AND WARMING AT RIDGE TOP LEVEL TO SEE THE SPLIT OCCUR. STILL HAVE SOME TIME TO CONSIDER. AS STATED ABOVE THE NEXT BIG WEATHER QUESTION IS THE EXTENDED PERIOD. WILL HAVE TO KEEP A CLOSE WATCH ON THE LONG RANGE MODEL RUNS OVER THE NEXT COUPLE OF DAYS. THE POLAR FLOW IS BECOMING ENERGIZED AGAIN AND LOOKS LIKE SUNDAY COULD BE A SNOWY DAY. PLENTY OF TIME TO WORK OUT THE DETAILS...BUT IT W I L L H A V E TO BE WATCHED CLOSELY. ...DAYS 3 THROUGH 7... THE CURRENT AVN AND MRF MODEL RUNS MOSTLY SUPPORTS THE FORECASTS FOR FRIDAY THROUGH SUNDAY...EXCEPT THAT IT INDICATES A SIGNIFICANT SNOW EVENT SUNDAY FOR EASTERN KY. THIS OCCURS AS A DEEP TROUGH MOVES THROUGH THE LOWER MS VALLEY...WHILE A FRONTAL WAVE SWINGS FROM THE GULF COAST STATES UP THE CAROLINA COAST. ALSO...A DOUBLE JET STREAK STRUCTURE DEPICTED AT 300 MB WOULD ENHANCE VERTICAL MOTION OVER EASTERN KY. FOR NOW...WE WILL WORD IT AS SNOW LIKELY SUNDAY. BEYOND THAT...WITH FAST FLOW DEVELOPING ACROSS THE PACIFIC...FORECAST CONFIDENCE IS LOW SO THE FORECASTS FOR MONDAY AND TUESDAY WILL NOT BE CHANGED. .GRIDDED DATA... MODIFIED THE GRIDDED DATA FOR THE FIRST THREE PERIODS TO ADJUST HOURLY TEMP/DWPT/WIND/SKY. POPULATED WITH RUC AND MODIFIED TO PRESENT SATELLITE TO GET A TREND ESTABLISHED. AVN MOS APPEARS TO BE DOING WELL AND HAVE TRIED TO STAY CLOSE TO THAT. STILL NO MOS DATA IN THE GFE SUITE SO HAVE ADJUSTED MAX/MIN/POP TO RESEMBLE THE CURRENT MAV DATA. ISC GRIDS OUT SHORTLY. .PRELIMINARY CCF...FOR COORDINATION ONLY... JKL 24 16/32 26 6100 LOZ 23 14/35 18 5100 .JKL...NONE. LEWIS/SCHAUB ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 430 PM EDT WED FEB 27 2002 MAIN FCST CONCERNS INCLUDE -SN/LES POTENTIAL WITH NEXT CLIPPER SHRTWV AND BOUT OF COLD AIR THURSDAY INTO FRIDAY. WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD TROF OVER THE CONUS. WITH MAIN TROF AXIS INTO THE ERN STATES NW MID/UPR LVL FLOW PREVAILED TOWARD THE WRN GRT LAKES. NEXT SIGNIFICANT UPSTREAM SHRTWV WAS LOCATED NW ND. AT THE SFC...A TROF EXTENDED INTO THE THE CNTRL DAKOTAS FROM LO PRES OVER NW ONTARIO WITH A DOWNSTREAM RDG INTO ERN MN. WAA/ISENTROPIC LIFT AHEAD OF THIS SYSTEM SUPPORTED AREA OF MID/HI CLD FROM THE DAKOTAS INTO NRN MN AND SOME PATCHY -SN INTO ERN OVER ERN ND. KMQT 88D AND VIS LOOP INDICATED REMNANTS OR LES HAD DIMINISHED QUICKLY TO PATCH OF BKN CLDS/FLURRIES INTO NE PORTION OF THE CWA AND SHOULD END QUICKLY. MDLS ARE IN REASONABLE AGREEMENT WITH TIMING/STRENGTH AND PLACEMENT OF FEATURES AFFECTING UPR MI THROUGH SATURDAY. AS USUAL...ETA IS EXPECTED TO HANDLE AFFECTS OF THE GRT LAKES BEST AND IS USED FOR DETAILS IN LOW LVL WIND FIELDS. TONIGHT...WITH MAINLY CLEAR SKIES OVER THE AREA AND DIMINISHING WINDS WITH APPROACH OF THE RDG...EXPECT TEMPS WILL DROP OFF QUICKLY TIL MID/HI CLD SPREAD ACRS CWA BTWN 03Z-09Z...PER ETA 700-500 RH FCST. LK-H8 DELTA/T TO NEAR 15C ALONG WITH INCREASING LOW LVL CONVERGENCE NEAR THE TROF ALONG WITH SYNOPTIC LIFT WITH INCREASING 850-500 QVECTOR CONVERGENCE SHOULD SUPPORT SHSN DEVELOPMENT LATE. AS SFC LO PRES MOVES TOWARD WRN LK SUPERIOR BY 12Z...EXPECT WINDS TO BACK ENOUGH TOWARD WSW SO THAT MOST -SHSN THAT DEVELOP WILL REMAIN MAINLY OFFSHORE. HOWEVER...SOME MAY CLIP THE TIP OF THE KEWEENAW. SO...MENTIONED SCT -SHSN LATE EVEN THOUGH 18Z ETA HAS CONTINUED WITH SOMEWHAT SLOWER PROGRESSION OF THE TROF. THURSDAY...SFC TROF/FRONT SWEEPS ACRS UPR MI WITH BAND OF -SN EXPECTED SUPPORTED BY LOW LVL CONVERGENCE NEAR THE FRONT AND WEAK TO MODERATE QVECTOR CONVERGENCE ASSOCIATED WITH THE SHRTWV. MOST SIGNIFICANT ACCUMULATIONS EXPECTED OVER THE WEST AS WINDS VEER TO THE NW AND DELTA/T INCREASES TO NEAR 18C. HAVE KEPT MINOR 1-3 INCH AMOUNTS GIVEN RELATIVELY QUICKLY MOVEMENT OF THE TROF AND STRONGLY VEERING WIND LLVL WINDS. ONSHORE FLOW ARRIVES MAINLY AFT 21Z FOR THE ERN PORTION OF THE CWA...LIMITING CHANCE FOR MORE THAN MINOR ACCUMULATIONS. THURSDAY NIGHT INTO FRIDAY...EVEN THOUGH DELTA/T INCREASE TO AOA 20C...INVERSION HGTS FALL OFF TO 4K-5K FT. LIMITED 70SM FETCH WITH 320 FLOW INTO WRN UPR MI SHOULD LIMIT ACCUMULATIONS TO 1-3 INCH RANGE WHILE 2-4 INCH AMOUNTS EXPECTED FOR ALGER-LUCE-NRNSCHOOLCRAFT WITH MORE SUBSTANTIAL FETCH. FRIDAY...ALTHOUGH LAKE INDUCED THERMAL TROF PERSISTS BACKING WINDS WITH INCREASINGLY ACYC FLOW WILL KEEP LES IN CHECK DESPITE CONTINUED LARGE INSTABILITY (DELTA/T OVER 20C) OVER THE LAKE. BY FRIDAY NIGHT...ONLY SCT -SHSN EXPECTED WITH MAINLY WRLY FLOW. SATURDAY...AS SFC LO PRES MOVES TOWARD SE ONTARIO AND SFC RDG EXTENDS TOWARD THE UPR MS VALLEY...AVN SUGGESTS WINDS WILL VEER AGAIN TOWARD NW WITH SHSN INTO AREAS FAVORED BY NW FLOW. SUNDAY THROUGH WEDNESDAY...MDLS HAVE COME INTO BETTER AGREEMENT WITH TIMING AND STRENGTH OF CLIPPER SHRTWV MOVING TOWARD THE GRT LAKES MONDAY AS MRF AND 12Z AVN HAVE COME MORE LINE WITH UKMET/ECMWF IN SLOWER MOVEMENT OF THIS SYSTEM. EXPECT POSSIBILITY OF WAA -SN DEVELOPING MONDAY FOLLOWED BY TRANSITION TO NW FLOW LES MONDAY NIGHT INTO EARLY TUESDAY. 12Z AVN ALSO HAS BACKED OFF ON AMOUNT OF COLD AIR MOVING IN BEHIND THIS SYSTEM...WITH H8 TEMPS TO NEAR -12C TO -14C...CLOSER TO THE ECMWF. SO...ANY LES SHOULD BE ON THE RELATIVELY LIGHT. MRF...12Z AVN EXT...AND 12Z UKMET SUGGEST BROAD TROF WILL DEVELOP OVER THE WRN CONUS WITH SFC LO PRES DEVELOPING OVER THE PLAINS WHICH WOULD BRING POSSIBILITY OF MORE SIGNIFICANT WAA SNOW INTO UPR MI WED. .MQT...NONE. JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1120 AM EST WED FEB 27 2002 ...DROP LAKE EFFECT SNOW ADVISORY NW CWA/KEEP IT GOING SW THIS AFTERNOON... RADAR LOOPS AND SATELLITE IMAGES CONFIRM WHAT MODELS FORECAST... THAT IS A DECREASING TREND IN THE LAKE EFFECT SNOW ACTIVITY THIS AFTERNOON. THE REAL QUESTION WAS IF AND WERE WE SHOULD KEEP THE LAKE EFFECT SNOW ADVISORY GOING THIS AFTERNOON? WE HAD REPORTS OF 4 TO 6 INCHES SINCE MIDNIGHT OVER A SIGNIFICANT SECTION OF WESTERN KALAMAZOO COUNTY...CENTRAL AND EASTERN VAN BUREN... MOST OF ALLEGAN...AND SOUTHWEST OTTAWA COUNTIES. THE 1530Z RADAR SHOWS THE HEAVY SNOW BANDS OVER THEN NW CWA HAVE FALLEN APART AND SFC OBS SHOW 1 TO 3 MILES IN SNOW SHOWERS THERE. OVER THE SW CWA... SNOW SHOWERS CONTINUE AND VIS HAS GOTTEN DOWN TO 1/4SM S+ AZO IN THE LAST HOUR. EVEN THERE THE SNOW BANDS HAVE DECREASED IN INTENSITY. HOWEVER... THE RUC SHOWS AS THE SFC TROUGH MOVES SOUTH THROUGH THE SRN CWA... AND THE UPPER SYSTEM MOVES OUT... THE SUBSIDENCE INVERSION DECREASES TO 5000 BY BY 21Z. THE SFC WIND CONVERGENCE DECREASES SIGNIFICANTLY THIS AFTERNOON OVER THE MOST OF THE WESTERN CWA AS WINDS BECOME MORE NNW FROM THE SFC THROUGH 700 MB. THE MEAN 1000/850 RH DROPS FROM OVER 90 PCT AT 12Z OVER THE NW CWA COUNTIES TO UNDER 85 PCT. THUS AFTER COORDINATING WITH APX I WILL DROP THE LAKE SNOW ADVISORY OVER THE NW CWA. MEANWHILE... OVER THE SOUTHWEST CWA... IT WILL TAKE MID AFTERNOON FOR THE INVERSION HEIGHT TO REALLY CRASH THERE AND FOR THE DRIER AIR TO MOVE IN. SO... AFTER COORDINATING WITH IWX... I WILL KEEP THE SNOW ADVISORY GOING THERE FOR THIS AFTERNOON. ELSEWHERE... SNOW SHOWERS WILL GRADUALLY DIMINISH AS THE INVERSION HEIGHTS FALL TO AROUND 5000 BY BY MID AFTERNOON AND WINDS BELOW THE INVERSION ARE MORE NNW THEN NW (BEHIND THE SFC TROUGH). THE RUC SHOWS THE MEAN 1000/850 RH FALLS TO BELOW 70 PCT OVER THE CTNL CWA BY 21Z. TEMPS SHOULD HOLD IN THE MID 20S DUE TO THE CLOUDS AND COLD ADVECTION. SFC TEMPS ARE COLDER UPSTREAM THEN OVER THE GRR CWA SO HEATING WILL BE OFFSET BY COLD ADVECTION. THANKS FOR THE COORDINATION... IWX AND APX WDM .GRR...LAKE EFFECT SNOW ADVISORY THIS AFTERNOON FOR... OTTAWA...ALLEGAN...VAN BUREN AND KALAMAZOO. mi SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1050 AM EST WED FEB 27 2002 LATEST RUC40 LOOKS TO HAVE A GOOD HANDLE ON THE SYNOPTIC SITUATION. LATEST SFC ANALYSIS HAS TROF AXIS SLICING ACROSS THE CWA FROM JUST SOUTH OF KPTK...KOSW AND PROGRESSING SOUTH TOWARD KDTW. WITH THIS TROF AXIS...AN ENHANCED SFC CONVERGENCE COMBINING WITH LAKE EFFECT SNOW RESULTING IN A MODERATE SNOW BAND (VISIBILITIES HERE AT THE OFFICE WERE LESS THAN A MILE!) PER 88D REFLECTIVITIES. HOWEVER...850-700 RH SHOWS A VERY DRY AIRMASS OVER THE U.P. WHICH IS FORECAST BY THE RUC40 TO APPROACH THE TRI-CITIES SHORTLY AFTER NOON AND INTO THE CENTER CWA NEAR 4 PM. IN FACT REFLECTIVITIES FROM KAPX SHOWING A RAPID DECREASE MAKING PROGRESS ACROSS EXTREME NORTHERN LOWER ATTM. SO FOR THIS UPDATE...WE INTEND ON HITTING THE SNOW SHOWERS A BIT HARDER ACROSS THE SOUTH AND GRADUALLY TAPER OFF THE ACTIVITY ACROSS THE FAR NORTH. TEMPERATURES LOOK TO BE IN LINE WITH NEW LAMP GUIDANCE AND CURRENT FORECAST. WE WILL LOOK CLOSER AT THE POTENTIAL WEEKEND EVENT (12Z AVN AND ETAXX) WITH A FOLLOWUP FOR AN HWO (SPS). .DTX...NONE. BGM mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 504 AM CST WED FEB 27 2002 STRIPES OF STRATO-CU IN ADVANCE OF 850-700 MB THERMAL TROUGH OVER NERN CWFA RESULTING IN A FEW...ISOLATED SNOW FLURRY REPORTS NEAR GRENADA. LATEST RUC SHOWS THE THERMAL TROUGH MOVING EWD INTO NRN AL BY 14-15Z. EXPECT A FEW MORE CALLS OF SOME FLURRIES WILL COME AS FOLKS WAKE UP IN THE COLUMBUS...PHILADELPHIA AND MERIDIAN AREAS. FEEL THAT THIS CAN BE COVERED WITH SHORT TERM FORECASTS (NOWJAN) AS IT SHOULD HAVE LITTLE IMPACT DUE TO ISOLATED NATURE OF REPORTS AND THE VERY SHORT DURATIONS EXPECTED EARLY THIS MORNING. WILL LEAVE ZFP/SFP ALONE. FCSTR= 05/ .JAN... AR...NONE. LA...NONE. MS...NONE. ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1100 AM EST WED FEB 27 2002 ...UPDATING TO ISSUE LAKE EFFECT/WINTER WEATHER ADVISORY AND UPDATE SNOW TOTALS FOR THIS AFTERNOON THROUGH TONIGHT... 12Z SURFACE/MSAS ANALYSIS SHOWS SLIGHT RIDGING OVER THE AREA IN ADVANCE OF A SECONDARY COLD FRONT OVER CENTRAL MICHIGAN. PIT AND BUF SOUNDINGS ALREADY MOIST UP TO 600 MB. VORT AXIS PASSING THROUGH REGION AT THIS TIME. HOWEVER MODELS ARE SHOWING SHORTWAVE ASSOCIATED WITH SECONDARY COLD FRONT DIVING IN THIS EVENING. THIS WILL ACT TO FOCUS LIFT AND SHUNT LAKE EFFECT SNOW BAND SOUTH THROUGH THE AFTERNOON. 925 MB WINDS WILL BACK FROM SOUTHWEST TO NORTHWEST LATE TODAY...ALLOWING FOR A LOW SHEAR NORTHWEST FLOW. RUC AND MESO-ETA THETA-E CROSS SECTIONS SHOW IMPRESSIVE MIXING UP TO 700 MB THIS AFTERNOON WITH DIURNAL HEATING INCREASING LAPSE RATES. TEMPERATURES AT THE TOP OF THIS MOIST LAYER WILL BE -20 TO -22 C...COLD ENOUGH TO SUPPORT HEAVY BURSTS OF SNOW. INVERSION IS SHOWN TO LOWER TO 850 MB AS THE WAVE PASSES BY MIDNIGHT...HOWEVER MORE SCATTERED SNOW SHOWERS WILL BE POSSIBLE INTO TOMORROW MORNING BEFORE ANTICYCLONIC FLOW KICKS IN. 40 KNOT WINDS AT THE TOP OF THE LAYER WILL ALLOW FOR 30 MPH WIND GUSTS WITHIN HEAVIER SNOW SQUALLS. HAVE ISSUED ADVISORIES TO COVER WIDESPREAD TWO TO FOUR INCH AMOUNTS BY MIDNIGHT...WITH LOCALIZED HEAVIER AMOUNTS IN NORTHWEST WARREN AND ON THE RIDGES OF THE LAUREL MOUNTAINS. .CTP...LAKE EFFECT SNOW ADVISORY THROUGH THIS EVENING FOR WARREN AND MCKEAN COUNTIES. WINTER WEATHER ADVISORY THROUGH THIS EVENING FOR CAMBRIA AND SOMERSET COUNTIES. ROGOWSKI/RXR pa AREA FORECAST DISCUSSION FOR CENTRAL/N-EAST SD AND W-CENTRAL MN NATIONAL WEATHER SERVICE ABERDEEN SD 855 PM CST WED FEB 27 2002 CURRENT SFC TROF EXITING ERN CWA ON TIME...WITH LIGHT SNOW/FLURRIES DECREASING AS IT MOVES EAST. LATEST RUC SHOWS HIGH PRES AXIS MOVING THROUGH CWA OVERNIGHT. LITTLE CLOUD COVER NOTED ON SAT PIX WITH SUBSIDENCE TAKING PLACE BEHIND EXITING TROF. HAVE UPDATED ZONES TO REFLECT CURRENT SKY/PCPN TRENDS. CURRENT FCST LOWS SEEM REASONABLE AND HAVE LEFT ALONE. .ABR...NONE. HINTZ sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 215 PM CST WED FEB 27 2002 FORECAST QUANDARIES...TEMPS. CURRENT ASOS/AWOS OBSERVATIONS...REGIONAL SATELLITE/RADAR MOSIAC IMAGERY ...SHOWING LOW CLOUD DECK...FLURRIES/LIGHT SNOW SHWRS PLATEAU...CONTINUING TO HOLD TOGETHER ACROSS THE MID STATE. RUC PASSING VORT MAX ACROSS N PLATEAU EARLY AFTERNOON. MSAS/SFC HAND ANALYSES ILLUSTRATING TEMPS IN THE 20S...UPPER TEENS N PLATEAU...W-NWLY WINDS 10-20 MPH...WITH RIDGING BUILDING IN FROM E TX. UPPER AIR CHART DEPICTIONS SHOWING BASE OF UPPER LEVEL TROUGH HAS MOVED WELL TO OUR E...WITH NWLY FLOW ACROSS REGION. OF PARTICULAR NOTE...CLR SKIES NOTED FAR W AND SW ZONES. 12Z WED REGIONAL MODEL EVOLUTIONS THRU 12Z SAT IN GOOD AGREEMENT ...ESPECIALLY IN UPPER LEVELS. IN AGREEMENT WITH LATEST MODEL DIAGNOSTIC DISCUSSION THAT BOTH ETA/AVN INITIALIZED WELL AND ON USING A BLENDED MODEL FORECAST THRU PERIOD. MODELS SHOWING PRESENT CLOUD COVER MOVING WELL E OF MID STATE BY 06Z THU...SO TONIGHT WILL BE A GOOD RADIATIONAL COOLING EVENT AS SFC RIDGING MOVES E ACROSS THE GULF COAST STATES. WILL WAIT UNTIL PRESS TIME FOR FINAL DECISION...BUT AT THIS TIME WILL GO PTCLDY W TO CLDY EVENING E...BECOMING CLR AFTER MIDNIGHT. WILL ADDRESS ANY LINGERING PCPN ACROSS PLATEAU AS FLURRIES. WILL CONTINUE WITH MOSUNNY SKIES THU AND MOCLR SKIES THU NIGHT AS SFC RIDGING INFLUENCES CONTINUE ACROSS THE SE U.S. AND FLOW ORIENTATED FROM NWLY...TO ZONAL..TO SWLY BY 12Z FRI. SFC FRONT WILL MOVE FROM THE MIDWEST SWD INTO THE MS AND OHIO RIVER VALLEY BY 12Z SAT..THEN PUSH WELL E OF REGION BY 12Z SUN. ETA/AVN HINTING AT RAINFALL POSSIBLE BEFORE 00Z SAT FAR W PORTIONS...BUT AT THIS WILL LEAVE MENTION OUT AND LET FURTHER MODEL RUNS EXPLORE THIS POSSIBLITY. MODELS SHOWING CHANCE OF RAINFALL ACROSS MID STATE THROUGH 00Z SUN...AS FRONT PASSES THRU. THERE COULD BE A BREAK SAT NIGHT... BEFORE THE UPPER LEVEL TROUGH MOVES INTO THE MID STATE ON SUN. THIS WILL BRING AN ADDITIONAL CHANCE OF PRECIP ON SUN. REGION COULD EXPERIENCE MIXED PCPN IN THE MORNING HOURS ON SUN...ESPECAIALLY HIGHER ELEVATIONS AND PLATEAU...BEFORE BECOMING ALL RAIN LATER IN THE DAY. REST OF WEEK...RIDGING SFC AND ALOFT SHOULD ALLOW FOR PC SKIES THRU WED. TEMPS...IN AGREEMENT WITH OTHER REGIONAL OFFICES THAT MOS VALUES TOO WARM TONIGHT...WILL UNDERCUT MOS BY SEVERAL DEGREES. WILL GO WITH 10 TO 15 DEGREES W TO AROUND 10 N PLATEAU. TEMPS SHOULD REBOUND INTO THE 40S ON THU AS SWLY FLOW DEVELOPS...BUT STILL WELL BELOW SEASONABLE NORMS. WILL GO WITH 40 TO 45 RANGE W TO UPPER 30S PLATEAU. WILL GO WITH COMPROMISE SOLUTION FOR REST OF FORECAST PERIOD. TEMPS SHOULD APPROACH SEASONABLE NORMS ON FRI. THANKS FOR COORDINATION MRX...BHM...PAH...SDF...JKL PRELIMINARY NUMBERS FOR COORDINATION PURPOSES ONLY BNA BE 013/043/028/054 0001 CSV BE 011/038/024/050 0001 .BNA...NONE 14 JBW tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 1015 AM CST WED FEB 27 2002 CURRENT ASOS/AWOS OBSERVATIONS...REGIONAL SATELLITE/RADAR MOSIAC IMAGERY SHOWING GENERALLY MOCLDY SKY CONDITIONS ACROSS MID STATE... WITH PATCHES OF LIGHT SNOW SHOWERS CONTINUING. NO REPORTS RECEIVED OF ANY ADDITIONAL SIGNIFICANT ACCUMULATIONS. MSAS SFC ANALYSES ILLUSTRATING STABLE SFC CONDITIONS AS RIDGING DEVELOPS... ASSOCIATED WITH 1033B HIGH BUILDING ACROSS E TX. RIDGING PROVIDING W-NW WINDS WITH GUST TO 20KT NOTED NE OF BNA. UNSEASONABLE COLD TEMPS THIS MORNING...AROUND 20 BNA TO AROUND 15 N PLATEAU...AND DEWPOINTS IN THE SINGLE DIGITS. UPPER AIR CHART ANALYSES DEPICTING COLD POOL RIGHT OVER MID STATE... WITH 850MB TEMP -19 AND 500MB TEMP -37 AT BNA. BASE OF UPPER LEVEL TROUGH MOVING E OF MID STATE...WITH PROGRESSIVE NWLY FLOW DEVELOPMENT UPSTREAM AND SOME MOISTURE AROUND 700MB NOTED. 12Z BNA SOUNDING ILLUSTRATING COLD POOL CONDITIONS...WITH BEST MOISTURE BETWEEN 900-800MB AND PRECIP WATER VALUES AROUND 0.15 INCH. RUC SHOWING NWLY FLOW DEVELOPMENT CONTINUING THROUGH 00Z THU...AS UPPER LEVEL TROUGH MOVES INTO CNTRL ATLANTIC STATES. DISTURBANCES IN UPPER LEVEL FLOW SHOULD GENERALLY REMAIN TO OUR E. SATELLITE IMAGERY SHOWING WRAP AROUND MOISTURE ASSOCIATED WITH TROF AND CURRENT SNOW SHOWERS/FLURRIES BEGINING TO MOVE E OF MEM...AS HIGH PRESSURE PROGGED TO MOVE NEWD INTO THE S MS RIVER VALLEY BY 00Z THU. RUC SHOWING 850-700MB MOISTURE MOVING E OF REGION...WITH PRECIP WATER VALUES ALSO REMAINING LIGHT THRU 00Z THU. COULD BRIEFLY UPDATE TO MOCLDY SKIES...BUT BELIEVE CURRENT MOCLDY CLOUD COVER TRENDS WILL BE SHORT LIVED. THUS...WILL CONTINUE WITH PARTLY CLOUDY SKY CONDITIONS AS MOISTURE EXPECTED TO MOVE TO OUR E. THIS MESHES WELL WITH OTHER REGIONAL OFFICES SKY CONDITION FORECASTS. FLURRIES TO SNOW SHOWERS STILL LINGERING...AND WILL CONTINUE TO LEAVE IN FORECAST. GUSTS SHOULD DIMINISH...WITH WINDS FALLING INTO THE 10 TO 15 MPH RANGE. AS FOR TEMPS...12Z BNA SOUNDING SHOWING MAX TEMP OF 23. WITH BNA AT 10AM REGISTERING 22 DEGREES...THIS VALUE NOT REALISTIC. DO BELIEVE WE WILL SEE SOME WARMUP...WITH CAA SCENARIO AT ITS DEPTH. BELIEVE CURRENT LAMP GUIDANCE VALUES MORE REALISTIC WITH UPPER 20S BNA TO MID 20S PLATEAU. THIS IN LINE WITH MORNING CCF ISSUANCE AND MESHES WELL WITH OTHER REGIONAL OFFICES ZONES ALSO. AS A RESULT...WILL NOT UPDATED FORECAST AT THIS TIME. WILL CONTINUE TO MONITOR SITUATION FOR LATER UPDATE. .BNA...NONE 14 JBW tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 832 PM EST WED FEB 27 2002 WILL OPT TO UPDATE ZFP TO MAKE MOSTLY SOME FIRST PERIOD CHANGES. SFC LOW TO MOVE UP INTO THE CANADIAN MARITIMES TONITE WITH CYCLONIC FLOW LEFT ACRS THE FA. WK RIDGE OF HI PRESS TO BUILD ACRS THE FA FROM THE WEST ON THU...AS A CLIPPER SYS MOVES ACRS THE GREAT LKS REGION. UPR TROF/TROP FOLD TO MOVE ACRS THE FA TONITE. S/W (AS SEEN IN H2O VAP IMAGERY) TO DROP DOWN ACRS THE FA FROM THE NW TONITE AS WELL. W-NW FLOW ALOFT TO PERSIST ACRS THE FA TONITE. 21Z 40KM RUC SHOWS TEMPS TO GET DOWN INTO THE TEENS TONITE WITH WESTERLY SFC WINDS AT 5-15 KTS. T1MIN TEMPS ARE IN THE SINGLE NUMBERS AND LWR TEENS TONITE AND SEEM A LIL ON THE COOL SIDE GIVEN CURRENT MESONET OBS. FEW TWEAKS TO FIRST PERIOD TEMPS/WINDS BASED ON RUC DATA AND CURRENT OBS TRENDS. SOME MID-LVL MSTR TO LINGER ACRS THE FA TONITE. GOOD LOW-LVL MSTR TO LINGER ACRS THE FA TONITE AS WELL. BEST H85 FGEN TO BE LOCATED MOSTLY TO THE EAST OF THE FA TONITE THOUGH. PW VALUES TO BE AOB 0.25" ACRS THE FA TONITE. RUC SHOWS MOST OF ANY MEASURABLE PCPN TO OCCUR ACRS THE HIR TRRN TONITE. RUC/AVN/ETA SHOW BLO 0.25" OF QPF ACRS THE FA TONITE. GOOD H85 CAA TO TAKE PLACE ACRS THE FA TONITE...THEN WAA ON THU. COLDEST CORE OF AIR AT H85 TO MOVE BY TO THE NORTH OF THE FA TONITE AND ON THU. MID-LVLS TO BASICALLY BE DRY ACRS THE FA ON THU. SOME LOW-LVL MSTR ADVECTION TO TAKE PLACE ACRS THE FA LATE ON THU...WITH SOME AMT OF LOW-LVL MSTR CONTINUING TO LINGER ACRS THE FA ON THU. LOW-LVL LAPSE RATES TO BE HI ACRS THE FA TONITE AND ON THU. ETA BUFR DATA SHOWS ANY LES OFF LK ONT TO DROP TO THE SOUTH OF THE FA TONITE. FOG PRODUCT SHOWS SOME BREAKS IN THE CLD COVER ACRS THE CENTRAL/WRN FA ATTM. BUFCAN/88D MOSAIC SHOWS MUCH OF THE PCPN ASSOCIATED WITH THE COASTAL STORM PULLING AWAY FROM THE FA ATTM...WITH JUST SCT PCPN LEFT ACRS MUCH OF THE FA. HAVE HELD ONTO EAST-WEST CHAMP VLY ZONE GROUPINGS BASED ON EXPECTED FLOW INTO THE WRN SLOPES OF THE GREEN MTNS FOR THE REST OF TONITE AND RE-COMBINED THE REST OF NE/NC VT TOGETHER FOR THIS UPDATE PACKAGE. HAVE DROPPED POPS A TAD ACRS THE ENTIRE FA AND MENTIONED SOME SN ACCUMULATIONS MOSTLY IN THE HIR TRRN FOR THE OVRNITE PERIOD. SNOWFALL RATIOS OF 10 TO 20-TO-1 EXPECTED ACRS THE FA TONITE...SO MOSTLY LESS THAN 4" OF SN EXPECTED ACRS REGIONS WHERE THE PCPN WILL LAST THE LONGEST. NO CHANGES...OTHER THAN COSMETIC ONES...TO THE REST OF THE GOING ZFP EXCEPT TO REMOVE SOME BOGUS IFPS WORDING TO SUN/MON FORECAST. WRK ZONES OUT UNDER ALBWRKCWF. FINAL ZFP BY 9 PM. .BTV...NONE. MURRAY vt AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GOODLAND KS 915 AM MST THU FEB 28 2002 LATEST RUC II FROM FSL VERIFYING THE SUSTAINED WINDS OF 15 TO 25 MPH WITH GUSTS TO 35 MPH THAT ARE OCCURRING OVER THE WESTERN AND CENTRAL CWA AS SURFACE TROUGH CONTINUES TO DEEPEN. UPDATED ZONES ACCORDINGLY. APPEARS THAT ETA 2M TEMPS MAY BE CONTAMINATED BY SNOW COVER AS THEY DONT TAKE TODAYS HIGHS ABOVE 35 EXCEPT OVER THE EXTREME SOUTH CWA. DESPITE SOME MID LEVEL CLOUDINESS 850 TEMPS FROM THE NGM/ETA GIVE HIGHS OF 40 TO 45 WITH AROUND 45 SOUTH. UPDATED ZONES ACCORDINGLY. MADE A FEW SKY COVER TWEAKS HERE AND THERE OTHERWISE NO OTHER CHANGES. .GLD...NONE. THEDE ks SOUTHWEST LOUISIANA AND SOUTHEAST TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1011 AM CST THU FEB 28 2002 SATELLITE SHOWING STRATOCU OVER COASTAL WATERS EXTENDING WEST THROUGH COASTAL TEXAS. CLOUDS SHOWING GRADUAL NORTH DRIFT AND ALIGNS WELL WITH LATEST RUC RUN AND 50+ MRH AT 8H. RUC MOVES 50+ LINE OVER SOUTHEAST TEXAS INTO SOUTHWEST LOUISIANA THIS AFTERNOON. WILL UPDATE ZONES INDICATING INCREASING CLOUDS ACROSS THESE AREAS. .PRELIMINARY NUMBERS... AEX 55/41/66/58/64 02666 BPT 58/45/69/61/68 03767 LCH 57/45/68/61/68 03767 LFT 57/45/68/61/68 03767 .LCH...NONE. MARCOTTE la COASTAL BEND FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 934 AM CST THU FEB 28 2002 COASTAL TROUGH IS NOW FIRMLY ESTABLISHED. WEAK REFLECTIVITY ECHOES CURRENTLY DETECTED PER CRP WSR-88D. SUFFICIENT ISENTROPIC UPGLIDE/LOWERING CONDENSATION PRESSURE DEFICITS(290K/295K) IS INDICATED PER THE LATEST RUC/ETA...THOUGH THESE MODELS TEND TO BE TOO AGGRESSIVE. WILL RETAIN MENTION OF SPRINKLES FOR COASTAL COUNTIES. WILL INCREASE COASTAL COUNTY WIND SPEEDS SOME GIVEN STRENGTHENING COASTAL TROUGH. FEEL MORE COMFORTABLE WITH THE RUC KEEPING THE WIND NORTHEAST GIVEN THE SYNOPTIC SCENARIO. PERHAPS THE IMMEDIATE COAST WILL VEER TO EAST LATE. WILL LOWER TEMPERATURES SOME ACROSS NORTH/WEST ZONES(IN LINE WITH THE RUC) WHERE THICK CLOUD COVER UPSTREAM OF COASTAL TROUGH TYPICALLY INHIBITS SIGNIFICANT RISES. MARINE...BOUY019 AND NWS OFFSHORE PLATFORM BLOWING NEAR 20 KNOTS...AND MORNING SOUNDING SHOWING WINDS OFF DECK AROUND 20 KNOTS. MODELS SHOW LEE TROUGH DEEPENING THIS AFTERNOON AND 850MB GRADIENT TIGHTENING. AS A RESULT...WILL GO WITH LOW END SCA THOUGH EXPECT CONDITIONS TO REMAIN BORDERLINE. OTHERWISE...REMOVE MORNING WORDING FROM COASTALS. .CRP...SCA GMZ230-235-250-255-270-275. 85/BB/PUBLIC 86/GW/MARINE-AVIATION tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 410 PM EDT THU FEB 28 2002 MAIN FCST CONCERNS INCLUDE LES POTENTIAL TONIGHT AND NEXT BATCH OF SNOW AND LES AFFECTING UPR MI OVER THE WEEKEND. WV IMAGERY AND RUC ANALYSIS PATTERN CHARACTERIZED BY BROAD TROF OVER CENTER OF NOAM. SHEARED UPSTREAM NRN STREAM SHRTWV EXTENDED FORM NE MN TOWARD WRN LK SUPERIOR. AT THE SFC...LO PRES WAS LOCATED NEAR CYXZ WITH A TROF AND ARCTIC FRONT EXTENDING TO WEST CNTRL UPR MI. VIS LOOP INDICATED MAIN LES ACTIVITY WITH LOW LVL CONVERGENCE NEAR THE FRONT AS KCMX REPORTED HEAVY SNOW AND WIND SHIFT TO NNW AS THE BAND MOVED THROUGH NEAR 1930Z. EARLIER LES VORTEX HAS TRANSITIONED INTO BROADER AREA OF CYCLONIC CIRCULATION WITH HEAVIER SNOWBANDS ALIGNING MORE WITH THE MEAN LOW LVL WIND. FARTHER UPSTREAM ON THE WRN LAKE...MORE CELLULAR WIND PARALLEL LES WAS DEVELOPING. H8 TEMPS NEAR -17C (LK-H8 DELTA/T TO NEAR 19C) PROVIDED AMPLE INSTABILITY. VERY DRY AIR AGAIN LURKED UPSTREAM OF THE LAKE WITH SFC TD FROM 0F TO -15F. CONVERGENCE AHEAD OF THE FRONT ALONG WITH QG SUPPORT FROM THE SHRTWV HAS ALSO BROUGHT AREA OF LESS ORGANIZED SHSN INTO NORTH CNTRL UPR MI AS KMQT 88D INDICATED ONLY PATCHY STRONG RETURNS. SINCE ETA HAS HAD VERY GOOD GRASP ON DETAILS OF LOW LVL WIND FIELDS...CORRECTLY TIMING/PLACING BEST LOW LVL CONVERGENCE...WL CONTINUE TO UTILIZE IN THE SHORT TERM. MDLS DIFFERENCES SHOW UP BY SAT IN DEGREE OF PHASING OF NRN AND SRN STREAMS AND IN TIMING WITH MID LVL TROF. HAVE SIDED WITH ETA/UKMET WHICH ARE IN VERY GOOD AGREEMENT THROUGH SATURDAY. AVN HAS BEEN LESS CONSISTENT AND SEEMS SLOWER TO CATCH UP WITH WESTWARD TREND FOR THE SYSTEM. TONIGHT...ETA SUGGESTS BAND OF MAX LOW LVL CONVERGENCE WILL SAG TO THE SOUTH FROM THE KEWEENAW/ONTONAGON BTWN 21Z-24Z TO IWD/ONT BTWN 03Z-06Z. DELTA/T ALSO INCREASES TO AOA 20C. HOWEVER...TRANSITION TO MULTIPLE WIND PARALLEL LES BANDS FOLLOWING BURST OF HEAVIER SNOW WITH STRONGER CONVERGENCE ZONE SHOULD BRING LOWER SNOWFALL RATES ESPECIALLY AS DRIER AIR BEGINS TO FILTER IN FROM THE NW. INVERSION HGTS ALSO FCST TO DROP FROM NEAR 7K FT TO 4K-5K FT BTWN 03Z-09Z. SO...EXPECT CONTINUED ADVY LVL SNOWFALL WITH ADDITIONAL AMOUNTS OF 2 TO 5 INCHES. OVER THE EAST...CONVERGENCE ZONE ARRIVES LATER(BTWN 00Z-03Z) WITH NNW FLOW OVERNIGHT. STRONG INSTABILITY COMBINED WITH LONGER FETCH AND LATER ARRIVAL OF LOWER INVERSION HGTS WILL BE ENOUGH TO BRING ADVY LVL SNOWS OF 2-6 INCHES INTO SNOWBELTS EAST OF MARQUETTE. LAKE EFFECT -SN/CLOUDS SHOULD KEEP TEMPS FROM DROPPING OFF TOO MUCH TONIGHT WITH READINGS AOA GUIDANCE VALUES. FRIDAY...RDGING BEGINS TO TAKE OVER DESPITE LINGERING LK INDUCED TROF EARLY. WITH BACKING WINDS...LES SHOULD DIMINISH FROM WEST TO EAST WITH -SHSN/FLURRIES ENDING LATE AS WINDS BECOME OFFSHORE. FRIDAY NIGHT INTO SATURDAY...ETA/UKMET SCENARIO WOULD BRING SYNOPTIC SNOWFALL INTO AT LEAST THE ERN HLF OF UPR MI BTWN 06Z-12Z SAT...WITH BEST CHANCE OF ACCUMULATIONS OVER THE SOUTHEAST. SYNOPTIC MOISTURE AND LIFT ALONG AND WIND FIELDS ARE A BIT WEAK SATURDAY FOR DECENT LAKE ENHANCEMENT. BUT IF SYSTEM CONTINUES WESTWARD TREND...MORE SIGNIFICANT AMOUNTS NEAR LK SUPERIOR IN EAST PORTION WOULD OCCUR. SATURDAY NIGHT INTO SUNDAY...SOME OF THE COLDEST AIR OF THE SEASON SINKS INTO THE WRN LAKES WITH H8 TEMPS DOWN TO NEAR -28C. ALTHOUGH CONFIDENCE IN DETAILS AT THIS TIME RANGE ARE LOW...GENERAL SCENARIO IS REASONABLE. ETA SUGGESTS LK INDUCED E-W THERMAL TROF OVER THE LK SATURDAY WILL SAG TO THE SOUTH WITH NW FLOW AREAS INITIALLY FAVORED BEFORE NRLY FLOW LOCATIONS SEE BETTER LES. WHILE INSTABILITY IS VERY STRONG...H8 TEMPS THAT COLD ALONG WITH VERY DRY ARCTIC AIRMASS WOULD FAVOR FORMATION OF SMALLER SNOWFLAKES AND MAKE SIGNIFICANT ACCUMULATIONS MORE DIFFICULT. MONDAY THROUGH THURSDAY...EXTENDED MDLS ARE IN REASONABLE AGREEMENT IN TAKING CLIPPER SHRTWV AND SFC LO JUST NORTH OF LK SUPERIOR. WITH LITTLE TIME FOR SIGNIFICANT MOISTURE INFLOW...LEFT WITH CHANCE -SN POPS WITH ASSOCIATED WAA/ISENTROPIC AND WEAK TO MODERATE QG FORCING. EXPECT COLD AIR IN THE WAKE OF THIS SYSTEM MAY NOT BE QUITE AS COLD AS ADVERTISED BY THE AVN/MRF WITH H8 TEMPS CLOSER TO -12C TO -14C DEPICTED BY THE ECMWF. BY WEDNESDAY/THURSDAY MRF AND 12Z AVN AND UKMET DROP HEIGHTS OVER THE NW CONUS WITH SFC LO MOVING TOWARD THE WRN LAKE FROM THE PLAINS. ECMWF DEPICTS A WEAKER SFC LO WITH LESS UPSTREAM HEIGHT FALLS AND WNW MID LVL FLOW TOWARD UPR MI. EITHER SCENARIO SUGGESTS AT LEAST CHANCE POPS FOR SNOW. WITH TIMING UNCERTAINTIES AT DAYS 6/7 WILL NOT REFINE TIMING/WORDING FOR TRANSITION TO SHSN IN THE WAKE OF THE SFC LO. .MQT...LAKE EFFECT SNOW ADVISORY TONIGHT MIZ001>003-009. LAKE EFFECT SNOW ADVISORY...TONIGHT EARLY FRI MIZ006-007-014. JLB mi NORTHEAST MONTANA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GLASGOW MT 930 AM MST THU FEB 28 2002 UPDATE PLANNED. .SHORT TERM...WILL FRESHEN WINTER WEATHER ADVISORY BUT ALSO CONTINUE IT FOR AT LEAST A FEW HOURS LONGER. THIS IS THE TIME OF SCHOOL TOURNAMENTS AND NEWBORN LIVESTOCK ACROSS THE CWA SO WILL KEEP FORECAST CONSERVATIVE AND COLD. RUC DEPICTS SHORTWAVE IN REGION IS SLOWLY SAGGING ALONG THE WESTERN ZONES AND PULLING THE ARCTIC AIR MASS BEHIND THROUGH THE NORTHEAST ZONES. SURFACE HIGH ASSOCIATED WITH THE ARCTIC AIR MASS IS GENERATING NORTHEAST WINDS ACROSS THE CWA WHICH WILL HELP KEEP THE REGION CHILLED. PRECIP BANDS IN RUC CLOSELY ALIGNED WITH RADAR AND CURRENT OBSERVATIONS SO TREND LOOKS REASONABLE. SATELLITE IR IMAGERY SHOWS A WEAKENING AND PROGRESSION OF THE SHORTWAVE OUT OF THE IMMEDIATE CWA. THERE IS SIGNIFICANT COLD AIR INDICATED WITH ADDITIONAL CLOUD BANDS DROPPING DOWN FROM CANADA THAT COULD TRIGGER ADDITIONAL SNOW DURING THE DAY. AMOUNTS SO FAR HAVE RANGED BETWEEN 1-3 INCHES AND LITTLE MORE IS EXPECTED... MAYBE ANOTHER INCH IN SOME FAVORED PLACES. EXPECT SNOW TO END OVER THE CWA LATE THIS AFTERNOON SO WILL ONLY TWEAK FIRST PERIOD WORDING. NEW ETA PULLS ANOTHER SHORTWAVE OUT OF THE NORTHERN FLOW TONIGHT AND TOMORROW FOR CONTINUED INTERESTING CONDITIONS. WILL EVALUATE THE IMPLICATIONS FOR THE AFTERNOON PACKAGE BUT AT FIRST GLANCE LOOKS LIKE A COLD PATTERN SETTING UP FOR THE NEXT COUPLE DAYS. MCNULTY .LONG TERM...MODELS AGREE ON A WARMUP FOR SUNDAY LASTING INTO MONDAY WITH NORTHERLY FLOW ALOFT SHIFTING TO THE NORTHWEST. BEYOND MONDAY...MODELS DIFFER IN THEIR SOLUTIONS ALTHOUGH THEY ARE TRENDING TOWARDS SOME FORM OF AN UPPER TROUGH OVER THE FORECAST AREA. FORRESTER KGGW JBB /016 906/010 903/026 8171000 EEEE 015/034 011/030 012/028 011/026 011/ 79122112120 KGDV JBB /015 905/012 902/026 8183000 EEEE 013/036 013/033 011/032 010/030 010/ 79122112121 .GGW...WINTER WEATHER ADVISORY MTZ016-017...MTZ020-027 AND MTZ060 mt