AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 720 AM EST SAT FEB 22 2003 HAVE UPDATED ZONES AND COASTAL WATERS FORECASTS FOR NEWEST TORNADO WATCH #18 THAT COVERS ALL BUT OUR FAR WRN CWFA. HAVE RECEIVED MARGINAL REPORTS OF SOME TREES DOWN IN PARTS OF SE AL. RED FLAG WARNING WAS CANCELLED DUE TO LIGHTER TRANSPORT WINDS AND LOWER DISPERSION INDICES NOW BEING EXPECTED. WINDS OVER THE COASTAL WATERS ARE BEGINNING TO STRENGTHEN AND SCA CONDITIONS SHOULD COMMENCE SHORTLY. .TLH... AL...NONE. GA...NONE. FL...SCA ALL MARINE ZONES. TJT PREVIOUS DISCUSSION FOLLOWS. ************************************************************ 355 AM EST SAT FEB 22 2003 --SYNOPSIS-- UPSTREAM SQUALL LINE IS BEGINNING TO FILL IN NICELY WELL INTO THE GULF DOWNSTREAM FROM THE VERY WELL DEFINED VORT MAX LIFTING NE INTO LA AT 0600Z. TORNADO WATCH #15 WAS RECENTLY ISSUED FOR MOST OF OUR CWFA. PLEASE SEE SPC OUTLOOKS AND MESOSCALE DISCUSSIONS FOR FURTHER DETAILS. ENTIRE CWFA IS NOW IN THE WARM SECTOR AND SURFACE LOW IS TRACKING NE FROM LA INTO MS. ETA BUFR SOUNDINGS PROG 0-1 KM SHEAR SUFFICIENT ENOUGH FOR FOR SOME BOW ECHO APEX TORNADO SPIN-UPS. LOWER TROPOSPHERIC WIND FIELDS ARE ALSO CERTAINLY STRONG ENOUGH FOR DAMAGING WIND GUSTS. --FORECAST-- LATEST SWODY1 KEEPS MODERATE RISK OVER MUCH OF OUR CWFA TODAY. FIRST CONCERN IS CLEARING OUT THUNDERSTORMS THE PRECIPITATION. WILL GENERALLY FOLLOW ETA TIMING FOR THIS. FIRE WEATHER...WILL KEEP RED FLAG WARNING IN EFFECT TODAY DUE TO HIGH DISPERSION INDICES. RH VALUES SHOULD STAY WELL ABOVE CRITICAL VALUES WITH THE EXTENSIVE PRECIPITATION. MARINE: STILL EXPECTING SCA CONDITIONS TO COMMENCE LATER THIS MORNING. EXTENDED...NO CHANGES MADE. PRELIMINARY NUMBERS... TLH 074/043 069/041 8000 PFN 071/049 066/049 8000 DHN 072/043 068/043 8200 ABY 072/042 067/042 8000 VLD 075/045 069/040 8000 CTY 075/050 069/044 8000 .TLH... AL...NONE. GA...NONE. FL...SCA ALL MARINE ZONES. RED FLAG WARNING ALL ZONES TODAY. TJT PREVIOUS DISCUSSION FOLLOWS. ************************************************************** 810 PM EST FRI FEB 21 2003 SQUALL LINE APPEARS TO BE FORMING OVER SOUTH CENTRAL LA...SO WILL STILL BE A WHILE BEFORE IT GETS HERE. MEANWHILE...AREA RADARS SHOW ISOLATED SHOWERS AND THUNDERSTORMS ACROSS N FL AND SW GA...TO A LESSER EXTENT SE AL. RAINFALL AMOUNTS HAVE BEEN GENERALLY VERY LIGHT...LESS THAN A TENTH OF AN INCH...EXCEPT SE AL WHERE SOME LOCATIONS HAVE RECEIVED UP TO A HALF INCH PER RADAR ESTIMATES. STATIONARY BOUNDARY PERSISTS ACROSS THE CWA...WITH DEWPOINTS NORTH OF THE BOUNDARY IN THE 50S...SOUTH OF THE BOUNDARY IN THE 60S...FED BY GOOD SOUTHERLY FLOW OFF THE GULF. BASED ON RUC40 BEST OMEGA OVER MOB BAY AREA AROUND 09Z...SQUALL LINE ESTIMATED AT THIS TIME TO BE ENTERING WESTERN ZONES AROUND 12Z. FIRE WEATHER...A FIRE WEATHER WATCH IS IN EFFECT FOR ALL FL ZONES FOR SATURDAY BASED ON FORECAST HIGH WINDS AND HIGH DISPERSION VALUES. MARINE...WINDS AND SEAS REMAIN BELOW 15 KTS AND 4 FEET BUT ARE EXPECTED TO GRADUALLY INCREASE AND REACH SCA BY MIDNIGHT. HIGH WINDS ARE FORECAST TO LAST INTO SATURDAY...THEN DECREASE TO SCEC BY SUNDAY. NO SUBSTANTIVE CHANGES PLANNED FOR COASTALS OR ZONES ON UPDATE. .TLH... AL...NONE. GA...NONE. FL...SCEC BECOMING SCA OVERNIGHT ALL LEGS...DESTIN-AAF-SUWANNEE RIVER FIRE WEATHER WATCH ALL AREAS SATURDAY. AFD PREVIOUS DISCUSSION FOLLOWS ***************************************************** INITIAL LINE OF SHOWERS & ISOLATED TSTMS CONTINUES TO PUSH ACROSS SE AL & THE WESTERN FL PANHANDLE THIS AFTERNOON. EXPECTED WEAKENING HAS OCCURRED & ISOLATED SEVERE STORMS LOW AT THIS TIME. SHORTWAVE ENERGY ASSOCIATED WITH THIS AREA WILL CONTINUE TO PUSH NE. TRAILING END WILL BRING A CHANCE OF PRECIP TO MAINLY CENTRAL & WESTERN PARTS OF CWA. HAVE SEEN CLOUDS THICKEN OVER CWA THIS AFTERNOON WITH THE MORNING CONVECTION...& HAS KEPT TEMPS A BIT COOLER THAN PREVIOUSLY EXPECTED. SURFACE ANALYSIS HAS A WARM FRONT OVER NORTH FLORIDA & IT IS EXPECTED TO MOVE NORTH AS THE LOW CENTER IN THE WEST ORGANIZES & MOVES NE. MODELS CONTINUE TO SHOW MAIN TSTM THREAT LATER THIS EVENING & OVERNIGHT. GFS HAS THE GREATEST LIFT...IS MOST AGGRESSIVE...& A BIT FASTER THAN ETA WITH SQUALL LINE OF SHOWERS/TSTMS NEAR TLH AT 12Z. BOTH ETA & NGM ABOUT 3-6 HRS SLOWER. MODELS DO HAVE MAIN MID-LEVEL DYNAMICS PUSHING ACROSS AREAS NORTH OF CWA...BUT LOBE DOES PUSH THROUGH. ETA DOES KEEP THE GREATEST INSTABILITY OFFSHORE WITH A FINGER SURGE INTO N FL...WHILE GFS PUSHES LI TO -4 WELL INLAND. WILL SEE CAPE VALUES REACH AROUND 500 WITH HELICITY AROUND 250. LOW LEVEL JET ALSO REACHES 40-50 KNOTS WITH SOME LIMITED VEERING. CURRENT SPC GUIDANCE HAS A MOD-SLIGHT RISK OF SEVERE STORMS...& THIS LOOKS GOOD WITH MAIN THREAT DAMAGING WINDS WITH ISOLATED TORNADOES POSSIBLE. BY 18Z SATURDAY...MOST OF CONVECTION EXPECTED TO BE MOVING ACROSS TO OUT OF THE EASTERN CWA AS HIGH PRESSURE BUILDS IN. THEN THE NEXT SYSTEM IS RIGHT ON ITS HEALS WITH A BASICALLY DRY FRONT LATE MONDAY PUSHING ACROSS THE AREA. FIRE WEATHER...NO HIGHLIGHTS TODAY. WINDS ON SATURDAY WILL BE ABOVE 15 MPH SO A FIRE WEATHER WATCH IS IN EFFECT AT THIS TIME. MARINE...EXPECT WINDS & SEAS TO GRADUALLY REACH SCA BY MIDNIGHT & LAST INTO SATURDAY. THEN LOWERING TO SCEC BY SUNDAY. EXTENDED (MONDAY THROUGH FRIDAY)...A MAINLY DRY COLD FRONT EXPECTED LATE MONDAY...BUT BASICALLY DRY THROUGH MID-WEEK. THEN NEXT FRONT WITH PRECIP LATE THURSDAY TO FRIDAY. PRELIMINARY NUMBERS... TLH 062 074 042 069 8700 PFN 063 072 048 067 8500 DHN 062 072 042 067 8500 ABY 062 072 041 066 8700 VLD 063 074 044 069 8700 CTY 065 075 049 070 8720 .TLH... AL...NONE. GA...NONE. FL...SCEC BECOMING SCA OVERNIGHT ALL LEGS...DESTIN-AAF-SUWANNEE RIVER FIRE WEATHER WATCH ALL AREAS SATURDAY. MCT fl AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LOUISVILLE KY 600 PM EST SAT FEB 22 2003 GETTING REPORTS OF +SN OVER DUBOIS CO ATTM, WITH ABOUT 1/2" ACCUMS SO FAR AND A FEW ACCIDENTS. ORANGE CO, HWVR, IS STILL IN RA BUT CHANGING OVER. FOR THE TIME BEING WILL LEAVE CURRENT FCST INTACT, BUT WILL HAVE TO MONITOR ETA/RUC FCSTS OF MORE SN TWDS MIDNIGHT ACROSS SRN IND AND NRN KY, SUCH AS THE 18Z ETA SUGGESTING DECENT SN AT KMDN CENTERED AROUND 6Z/SUN. SHOULD THIS MATERIALIZE, A LOW-END SN ADV MAY BE NEEDED ACROSS SRN IND. WILL KEEP WATCH ON THIS. NEVER SEEING THE WARM SECTOR TODAY, SRN IND'S ROAD TEMPERATURES WILL SOON BE CONDUCIVE TO SN ACCUMS. ALSO REFREEZING MAY BE AN ISSUE. .SDF...NONE. XXV ///PREV AFD/// MODERATE TO HEAVY RAINFALL CAME TO CENTRAL KENTUCKY THIS MORNING AND INTO THE AFTN AS A RATHER WELL DEVELOPED AREA OF LOW PRESSURE MOVED FROM MIDDLE TENNESSEE NORTHEAST INTO KENTUCKY. FURTHER, NORTHEAST MOVEMENT IS XPCTD EARLY TONIGHT WITH CONTINUED PROPAGATION TO THE NORTHEAST XPCTD OVERNIGHT. THE CENTER OF LOW PRESSURE IS EXPECTED TO BE LOCATED OVER NEW YORK STATE BY 12Z SUNDAY. AS A RESULT...COLDER AIR WILL SPREAD OVER CENTRAL KENTUCKY. WHILE MODERATE TO OCCASIONALLY HEAVY RAINFALL WAS GENERATED OVER CENTRAL KENTUCKY ON SATURDAY...AMOUNTS WERE NOT SUFFICIENT TO CAUSE ANY FLOODING. AVERAGE AMOUNTS FOR THIS RAINFALL EVENT WERE MOSTLY FROM 1 TO 1.5 INCHES. A SIGN OF SPRING WAS FELT OVER SOME PARTS OF THE REGION WITH SPOTTY TSTMS REPORTED. TEMPERATURES AT 18Z REGISTERED MOSTLY IN THE 40S AND 50S. THE MERCURY EVEN SOARED INTO THE LOWER 60S AT 18Z OVER A FEW COUNTIES OF THE SOUTH CENTRAL PORTION OF THE STATE. WILL LOOK FOR SOME SNOW MIXING IN EARLY EVNG NORTH OF THE OH RIVER, AS COLDER AIR WORKS INTO THE REGION...THEN LATER IN THE EVNG FOR THE SRN AREAS OF THE STATE. SNOW ACCUM WISE, EXPECT AROUND 1" NORTH OF THE RIVER, LESS THAN 1" N AND E CTRL KY, AND LITTLE OR NO ACCUM S CTRL KY. GFS SEEMS TO BE THE SUPERIOR MODEL TO FOLLOW ALTHO ETA IN AGREEMENT. GFS MOS MNLY USED TO FORMULATE SHORT TERM. SOME SNOW PSBL SUNDAY NIGHT...BUT...BEST CHC OF ACCUMULATING SNOW WILL BE OVER A THE NORTHERNMOST CWA OR A FEW COUNTIES OF SCENTRAL IN AS A QUICK MOVING AND WEAKENING AREA OF LOW PRESSURE MOVES FROM SRN OK NE TO NEAR CINCINNATI BY 8AM EST MONDAY MORNING. .SDF...NONE. $$ CONGER ky SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 947 PM EST SAT FEB 22 2003 REGIONAL 88DS CONTINUE TO DEPICT THE EVOLUTION OF A SIGNIFICANT FRONTOGENETICALLY FORCED SNOWBAND EXTENDING FROM NEAR INDIANAPOLIS NORTHEAST TO NEAR PORT HURON. RECENT SPOTTER REPORTS FROM WITHIN THIS BAND INDICATED 1-2 INCH PER HOUR SNOWFALL RATES, WHICH IS ALSO CORROBORATED BY THE RECENT REPORTS FROM FORT WAYNE OF A SNINCR 2 (WITH SOME THUNDER SNOW). LATEST SHORT RANGE MODEL GUIDANCE (00Z RUC AND 00Z DTX CONVINIT MODEL) INDICATE THAT THE FORCING FOR THE SNOWFALL OVER THE SOUTHERN PORTIONS OF THE FORECAST AREA WILL TRANSFORM FROM THE MID-LEVEL (AROUND 700MB AS PER THE KDTX VWP) FRONTOGENESIS TO THAT OF STRONG DEFORMATION ASSOCIATED WITH THE MID/UPPER LEVEL VORT MAX NOW OVER CENTRAL INDIANA. SEVERAL LIGHTNING STRIKES HAVE BEEN OBSERVED WITH THE COLD POOL ALOFT AS IT LIFT NORTHEAST TOWARD THE SOUTHERN TWO TIER OF COUNTIES. EXPECT THAT THERE WILL BE SEVERAL MORE HOURS OF MODERATE TO OCCASIONALLY HEAVY SNOW ACROSS THE WARNING AREA (ESPECIALLY EAST OF AN ADRIAN TO PONTIAC TO PORT HURON LINE) AS THE 500MB WAVES CONTINUES TO LIFT. WITHIN THE ADVISORY AREA, EXPECT THAT THE SNOW WILL GRADUALLY TAPER OFF TO PERIODS OF LIGHT SNOW BEFORE DIMINISHING TO FLURRIES. ACROSS THE FAR NORTHWEST (MIDLAND AND BAY COUNTIES) WILL DROP THE MENTION OF ACCUMULATING SNOWS AS THE DRY AIR CONTINUES TO WIN THE BATTLE. WILL CONTINUE TO THE GOING HEADLINES AS ADVERTISED AND ANTICIPATE THAT THEY WILL BE DISCONTINUED WITH THE MORNING PACKAGE ONCE THE HEAVY SNOW SUBSIDES. ZONES FORTHCOMING SHORTLY. .DTX...WINTER STORM WARNING...TONIGHT... MIZ055-062-063-068>070-075-076-082-083. WINTER WEATHER ADVISORY...TONIGHT... MIZ049-054-060-061. GALE WARNING...THROUGH SUNDAY MORNING... LAKE HURON AND LAKE ST CLAIR. MANN EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 940 PM EST SAT FEB 22 2003 COMBINATION OF TEMPERATURES AND WINDS WILL BE BORDERLINE FOR WIND CHILL ADVISORY (-25F WIND CHILLS) ACROSS THE EASTERN UP OVERNIGHT...BUT WILL BE CLOSE ENOUGH TO JUSTIFY A CONTINUATION OF THE ADVISORY ALREADY IN EFFECT. OTHERWISE...SIGNIFICANT SNOW HAS FOCUSED WELL S/SE OF THE FORECAST AREA...WITH ONLY FLURRIES LEFT BEHIND...VISIBILITY AT APN AND OSC HAS BEEN BASICALLY UNRESTRICTED FOR A COUPLE OF HOURS. THUS... REMOVED POPS FROM S/SE COUNTIES...BUT CONTINUED FLURRIES SOUTH OF THE STRAITS INTO THE OVERNIGHT HOURS. MEANWHILE...PER SATELLITE TRENDS/LATEST RUC40 FORECAST EXPECT MID/HIGH LEVEL CLOUD SHIELD STILL IN PLACE ACROSS THE FORECAST AREA TO ONLY SLOWLY RETREAT FROM W/NW TO E/SE OVERNIGHT...SO ADJUSTED CLOUD COVER TRENDS TO A MORE GRADUAL DECREASING CLOUDS OVERNIGHT...LATE ACROSS THE E/SE. FINALLY...MADE MINOR ADJUSTMENTS TO WIND FORECASTS...WITH 10-20 MPH WINDS N/W AND 15-25 MPH (GUSTING TO 30-35 MPH) WINDS E/SE. .APX...WIND CHILL ADVISORY...OVERNIGHT...MIZ008-015. ROWLEY mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 330 PM EST SAT FEB 22 2003 12Z RAOBS/LATEST WV LOOP AND RUC ANLSYS SHOW CONTD SPLIT FLOW ACRS NAMERICA. POTENT SHRTWV IN ACTIVE SUBTROPICAL BRANCH NOW IN LWR MS VALLEY...WITH DEEPENING LO PRES IN THE SE CONUS TAPPING GLFMEX MSTR AND CUTTING THIS MSTR SOURCE TO THE POLAR AND ARCTIC BRANCES OVR THE NRN TIER STATES AND SRN CAN. WEAK SHRTWV IN THE POLAR BRANCH NOTED OVR UPR MS VALLEY...AND THIS SYS TENDING TO MAINTAIN A WEAKLY CYC ENE GRADIENT FLOW INTO UPR GRT LKS BTWN THE DEEPENING SRN BRANCH LO AND ARCTIC HI PRES OVR SRN MANITOBA-ONTARIO (WHERE H85 TEMP ARND -25C AND SFC DWPTS GENERALLY IN THE -20S F). NRN EDGE OF ASSOCIATED HIER CLD SHIELD STRETCHES FM JUST NW OF IMT TO NR MQT AT 17Z...BUT SFC OBS/88D INDICATE NO PCPN IMPACTING CWA. 12Z YPL SDNG IN STABLE AIRMASS TO THE N SHOWS INVRN JUST ABV H9 WITH A VERY DRY TROP (PWAT 0.04 INCH). LLVL FLOW IN THE SHARPER PRES GRADIENT OVR THE UPR LKS IS RATHER AGEOSTROPHIC WITH CROSS ISOBARIC FLOW FM ONTARIO HI PRES ADVCTG VERY COLD/DRY AIR S THRU THE CWA TOWARD DVLPG SRN BRANCH STORM SYS. THERE IS ENUF OPEN WATER OVR THE ERN HALF OF LK SUP TO SUPPORT NMRS WND PARALLEL LES BANDS. ALSO ENUF OPEN WATER OVR THE W TO CAUSE FEWER BUT MORE DOMINANT WND PARALLEL BANDS...THE STRONGEST OF WHICH STRETCHES FM NE OF ISLE ROYALE TO OFF THE W COAST OF WRN CWA INTO NW WI...WHERE ASX HAS BEEN RPRTG VSBY 1/4SM +SN MUCH OF MRNG. MQT 88D/SAT PIX SHOW WDLY SEPARATED LES BANDS IMPACTING AREAS W OF MUNISING TO NR L'ANSE...WITH REFLECTIVITY GENERALLY AOB 20DBZ. 12Z APX SDNG SHOWS SHALLOW COLD WEDGE BLO SHARP INVRN AT H9 (WITH DRY AIR BTWN MOIST LYRS ASSOCIATED WITH POLAR BRANCH SHRTWV CLD SHIELD). APX SDNG AND 88D DEPICTION SUG LES OVR THE ECNTRL IS SEVERELY STRESSED BY DRY AIRFLOW OFF ONTARIO. IN FACT...SAT PIX/SFC OBS SHOW SOME CLRG OVR THE FAR ERN U.P. AS WELL AS OVR THE WRN 4 COUNTIES OF FA IN UNFVRBL NE LLVL FLOW. SKIES MCLR AT CMX. ANOTHER SHRTWV EMBEDDED IN ARCTIC BRANCH DROPPING SE THRU CNTRL CAN. MAIN FCST CONCERNS THIS PACKAGE INCLUDE LES TRENDS/TEMPS/WND CHILLS INTO SUN NGT...THEN PCPN CHCS ASSOCIATED WITH ARCTIC BRANCH SHRTWV NOW DROPPING INTO CNTRL CAN. FOR TNGT...MODELS SHOW POTENT SRN BRANCH SHRTWV/LO PRES MOVG JUST W OF THE APPALACHIANS...WITH UPR RDGING/H85-5 QVECTOR DVGC OVR THE NW GRT LKS BTWN THIS SYS AND SHARPENING ARCTIC BRANCH TROF DROPPING S TOWARD LK WINNIPEG. WEAKER POLAR BRANCH SHRTWV IN THE UPR MS VALLEY TENDS TO WEAKEN IN LARGE SCALE SUBSIDENCE BTWN THESE TWO MORE IMPORTANT FEATURES...AND LLVL FLOW OVR CWA FCST TO BACK TO MORE DUE N BY 12Z SUN IN RESPONSE TO THE EWD MVMNT OF THE POLAR BRANCH SHRTWV AND DEEPER CYC FLOW ARND LO PRES MOVG N TO THE SE. WITH SHIFTING WNDS...XPCT LES BANDS TO SHIFT AS WELL. ALTHOUGH DEEPER DOMINANT BAND EVIDENT ACRS WRN LK SUP ATTM...DCRSG FETCH LENGTH AND ORIENTATION OF BANDS ALG SHORTER AXIS OF LK WL TEND TO CAUSE ACTIVITY TO SHIFT TO MORE NMRS WND PARALLEL BANDS NOW EVIDENT ACRS THE E HALF. DRY ADVCTN SHUD GREATLY IMPACT ACTIVITY...AND ETA FCST SDNGS FOR IWD SHOW INVRN HGT SINKING AS LO AS 1.5K FT BY 12Z SUN. SLGTLY DIFFLUENT NATURE OF FCST GFS/ETA NR SFC WNDS AND H95 DVGC FCST BY ETA ALSO WL HAMPER LES ACRS THE W. WL MAINTAIN LO CHC POPS FOR SCT -SHSN/FLURRIES OVR WRN ZNS NR LK SUP. FARTHER E...LLVL FLOW ALSO IS GENERALLY DIFFLUENT...WITH ETA SHOWING ANY H95 CNVGC CONFINED TO BARAGA/MQT ZNS...BUT WITH INVRN HGT ONLY 2K FT MSL...SO ONLY SCT -SHSN THESE ZNS. AREAS E OF MUNISING WL BE DOWNSTREAM OF SHORTER FETCH/MORE ICE COVER ACRS THE FAR E LK...SO NOTHING MORE THAN FLURRIES. XPCT CLRG SKIES OVER THE SCNTRL THIS EVNG AS DEEPER MSTR ASSOCIATED WITH POLAR BRANCH SHRTWV SHIFTS E. AS SFC LO TO THE SE CONTS DEEPENING TNGT...GFS/ETA MAINTAIN TIGHT PRES GRADIENT OVR CWA WITH ENHANCED NLY FLOW DRAWING INCRSGLY COLD AIR S. ETA MAINTAINS A GENERAL 10 TO 20 KT SFC WND OVR ENTIRE FA WITH 25 TO EVEN 30KT WNDS FCST WITHIN SHALLOW MIXED LYR. ALTHOUGH STEADY WND WL PREVENT DECOUPLING AND TEMPS FM REALLY NOSEDIVING... ADVCTN OF UPSTREAM COLD AIR/H100-85 THKNS SUGS MINS WL FALL BLO MOS GUIDANCE AT LEAST SVRL DEGREES BLO ZERO NRLY EVERYWHERE TNGT XCPT NR THE LK SUP SHORELINE. SINCE 15 MPH/-5F AND 10 MPH/-10F TO REACH WND CHILL COMBINATION LIKELY TO BE MET OVR A GOOD PORTION OF THE FA RIGHT NXT TO LK SUP...HAVE OPTED TO GO WITH WND CHILL ADVY ALL LK SUP BORDER ZNS XCPT THE ONT/IWD...WHERE GRADIENT IS FCST TO BE A LTL WEAKER SO THAT SUSTAINED WNDS MAY NOT MEET 10 MPH CRITERIA AT MOST TIMES EVEN THOUGH TEMPS REACH -10F. APPEARS THERE WL BE ENUF LK SUP MODERATION TO MITIGATE TEMPS ACRS SCNTRL AS WELL WITH N WIND ALSO SHELTERED A BIT. SO WL HOLD OFF ON ADVY FOR NOW FOR MNM-ESC-ISQ. ON SUN...CWA STILL UNDER H5 RDGING/H85-5 QVECTOR DVGC BTWN ARCTIC AND SRN BRANCH SHRTWVS. AS PRES GRADIENT SLACKENS/LLVL FLOW BCMS LIGHTER AND MORE ACYC FOLLOWING DEPARTURE OF MAIN SFC LO...XPCT WND CHILLS TO EASE IN THE MRNG AND LES TO CONT DIMINISHING TREND. LINGERING SCT -SHSN WL TEND TO SHIFT E INTO MQT/ALGER ZNS. BUT LACK OF H95 CNVGC AND LOW INVRN HGTS AOB 2K FT WL HAMPER ACTIVITY. FARTHER W...XPCT NOTHING MORE THAN FLURRIES NR LK SUP. GIVEN SHALLOW NATURE OF COLD AIR AND ENHANCED COLD/DRY ADVCTN INTO DVLPG CYC TO THE E...HAVE TENDED TOWARD LWR ETA MOS GUIDANCE FOR MAX...BUT NOT QUITE AS EXTREME. MODELS HAVE SPEEDED UP ARRIVAL OF VIGOROUS ARCTIC BRANCH SYS FCST TO IMPACT CWA SUN NGT AND MON. BOTH SHOW H5 SHRTWV DIGGING SE INTO WI AND THEN E BY LATE MON...WITH DPVA/H85-5 QVECTOR CNVGC ARRIVING OVR W HALF OF CWA LATE SUN NGT. DESPITE FCST 12HR H5 HGT FALLS OF NR 120M FM 06Z-18Z MON...ETA SHOWS LTL SFC RESPONSE TO VIGOROUS DYNAMICS......NO DOUBT DUE TO VERY COLD/STABLE AIR IN PLACE. BUT THINK RESPONSE IS UNDERDONE ESPECIALLY SINCE LK SUP STILL A SOURCE OF SOME LATENT HEAT EVEN WITH ICE COVG...AND PREFER SOMEWHAT MORE VIGOROUS GFS SFC TROFFING ACRS CNTRL LK SUP WITH ARRIVAL OF DYNAMICS. ALTHOUGH PWAT FCST ONLY ARND 0.1 INCH...HAVE OPTED TO GO WITH LIKELY POPS ACRS THE ECNTRL ZNS NR LK SUP WHERE GFS SHOWS A BIT MORE ENHANCED LLVL CNVGC BEFORE A DRIER NW FLOW DVLPS MON AFTN AND PUSHES CNVGC E ALG WITH DPVA/QVECTOR CNVGC. WITH H85 TEMPS ARND -25C AS WELL AS LTL SUNSHINE AND TEMP ADVCTN...XPCT MON MAX TOWARD LO END OF MOS GUIDANCE. HAVE HIGHLIGHTED THE COLD IN ZFP. AS VIGOROUS SHRTWV AND DEEP ARCTIC AIR LIFTS OUT MON NGT...XPCT A DIMINISHING TREND TO CHCS FOR LINGERING SN EARLY...ESPECIALLY INLAND WHERE THERE WL BE NOTHING MORE THAN FLURRIES BY SUNDOWN MON. LO TEMPS WL GET QUITE FRIGID NR THE WI BORDER AS SKIES XPCTD TO LATE... AND WENT NR LO GFS MOS GUIDANCE FOR MINS IN THESE AREAS AS 12Z MODELS HAVE TRENDED TO MOVE SHRTWV/HIER RH E QUICKER. ARRIVAL OF DRY HI PRES/ ACYC FLOW WL RESULT IN DIMINISHING TREND TO SHSN NR LK W TO E ON TUE AS FLOW SHUD BACK MORE W BY LATE IN THE DAY N OF HI CENTER FCST TO PUSH INTO THE SRN LKS BY LATE IN THE DAY. RETURN OF SUNSHINE AND RISING H85 TEMPS SUPPORT MAX AT LEAST SVRL DEGREES HIER THAN ON MON. 00Z EXTENDED MODELS CONT TO ADVERTISE A DEAMPLIFICATION OF NRN BRANCH FLOW AFTER DEEP TROF EARLY IN THE WEEK WITH CONFLUENCE ZN/HI PRES RDG BTWN MORE ACTIVE SUBTROPICAL JET AND RETREATING NRN BRANCH DOMINATING LATE IN THE WEEK. ALTHOUGH MODELS SHOWS SRN BRANCH STORM SYS REMAINING S OF CWA LATE IN THE WEEK...ECMWF AND ESPECIALY THE 00Z/06Z GFS INDICATE COMPLEX INTERACTION BTWN THE BRANCHES MAY CAUSE LWRG HGTS/SOME CYC FLOW OVR UPR GRT LKS THU/FRI. SO AFTR DRY DAY ON WED WITH A MORE MODERATE WLY FLOW S OF NRN BRANCH SHRTWV PASSING FAR ENUF N TO MISS CWA WITH ANY -SN...WL CONT CHC OF -SN ON THU/FRI WITH NR NORMAL TEMPS. GFS ENSEMBLE MEAN SHOWS RELATIVELY LO PRES OVR SRN CAN WITH WLY FLOW OVR CWA NXT SAT WITH H100-5 THKNS ARND 525DM...SO XPCT A DRY DAY WITH NR NORMAL TEMPS. NO BIG STORMS OR COLD WAVES APPEAR ON THE HORIZON AFTER EARLY THIS WEEK AND THRU THE FIRST WEEK OF MAR WITH GFS ENSEMBLES ADVERTISING A FAIRLY LO AMPLITUDE WNW FLOW ALF. COORDINATED WITH DLH/GRB/APX. .MQT...WND CHILL ADVY LATE TNGT/EARLY SUN MIZ001-003>007-085. HEAVY FREEZING SPRAY WARNING E HALF OF LAKE SUPERIOR. KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1058 AM EST SAT FEB 22 2003 THE MAIN FORECAST CONCERNS WITH THIS UPDATE ARE THE LAKES EFFECT SNOW AND TEMPERATURES THIS AFTERNOON. WATER VAPOR IMAGERY...RUC AND ETA SHOWING A WEAK SHORTWAVE ROTATING THROUGH THE BASE OF A CLOSED LOW OVER NORTHERN MANITOBA. THIS SHORTWAVE IS MOVING THROUGH WESTERN UPPER MICHIGAN. IR AND VISIBLE IMAGERY SHOWING LAKE EFFECT SNOW BANDS OVER LAKE SUPERIOR THIS MORNING. SKIES ARE CLEAR OVER MOST OF ONTARIO AND MINNESOTA DUE TO THE DRIER CANADIAN AIR MASS ADVECTING IN. 280K ISENTROPIC ANALYSIS ALSO SHOW GENERAL SUBSIDENCE OVER THAT AREA. KINL 12Z RAOB DEPICT THE AIR MASS AS BEING ABOUT 15C COOLER AND DEW POINTS AROUND 15 TO 20C DRIER THAN KGRB. PRECIPITABLE WATER AT KINL WAS ONLY .1 INCH...AS COMPARED TO .33 INCH OVER KGRB. SURFACE ANALYSIS SHOWING A LOW OVER WESTERN TENNESSEE. CLOUD BANDS ROTATING AROUND THIS LOW IS MOVING OVER THE EAST AND CENTRAL UPPER MICHIGAN. SATELLITE STILL DEPICTS THAT THE WESTERN HALF OF LAKE SUPERIOR IS MOSTLY ICE COVERED...AND ONLY A SMALL PORTION OF EASTERN LAKE SUPERIOR IS OPEN. A NARROW RIDGE EXTENDING FROM THE DAKOTA THROUGH THE CENTRAL PLAINS SEPARATES THE LOW OVER TENNESSEE FROM ANOTHER LOW OVER CENTRAL HIGH PLAINS. AN UPPER LEVEL JET RACES FROM IOWA...ACROSS THE FORECAST AREA...INTO CENTRAL QUEBEC. THE WEAK SHORTWAVE OVER WESTERN UPPER MICHIGAN WILL MOVE ACROSS THE AREA THIS AFTERNOON...FOLLOWED CLOSELY BY ANOTHER SHORTWAVE ...SLIGHTLY DEEPER...MOVING INTO THE WESTERN U.P. THE LOW OVER TENNESSEE WILL EDGE NORTHEAST INTO THE OHIO VALLEY. CYCLONIC FLOW AROUND THIS LOW WILL KEEP THE WINDS OUT OF THE BACK THE WINDS SLOWLY NORTH THIS AFTERNOON. THE UPPER LEVEL JET WILL REMAIN OVER THE FORECAST AREA THROUGH THE AFTERNOON. THE DRIER AIR FROM MINNESOTA AND SOUTH CENTRAL CANADA WILL CONTINUE TO ADVECT INTO THE AREA. WATER-850MB DELTA-T'S WILL REMAIN BETWEEN 18C AND 20C OVER THE WESTERN U.P. CONDITIONS LOOK FAVORABLE FOR LAKE EFFECT SNOWS TO CONTINUE. THE LIMITING FACTOR WILL BE THE DRIER AIR MOVING INTO THE UPPER GREAT LAKES AND THE AMOUNT OF ICE ON THE LAKE. THE LAKE EFFECT SNOWS WILL CONTINUE OVER THE FORECAST AREA. THE HEAVIEST SNOW FALL EARLY WILL BE ISOLATED OVER THE HURON MOUNTAINS...AND SOME OF THE HIGHER TERRAIN IMMEDIATELY WEST OF MARQUETTE. AS THE WINDS BECOME MORE NORTHERLY THIS AFTERNOON...THE HEAVIER BANDS WILL SHIFT EAST TO MUNISING AND GRAND MARAIS AREA. THE 850MB THERMAL TROUGH OVER CANADA WILL MOVE LITTLE TODAY AND TONIGHT. SURFACE TRAJECTORY FORECAST SHOWING THE AIR MASS OVER EASTERN ONTARIO YESTERDAY WILL SHIFT OVER THE FORECAST AREA TODAY. THUS TEMPERATURES SHOULD CHANGE LITTLE THROUGH THE AFTERNOON. .MQT...HEAVY FREEZING SPRAY WARNING E HALF OF LAKE SUPERIOR. DLG mi SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 400 PM CST SAT FEB 22 2003 ...SNOW TONIGHT/SUNDAY MORNING AND ASSOCIATED WINTER WX HEADLINES FOR PORTIONS OF THE CWA ARE MAIN CONCERN... 12Z UPPER AIR DIAGNOSTICS AND WATER VAPOR IMAGERY FEATURING STRONG VORTEX THROUGH THE LOWER/MIDDLE MISSISSIPPI RIVER VALLEY...WHILE A MID TO UPPER SHORTWAVE TROUGH -- THE MAIN PLAYER IN THE LOCAL FORECAST TONIGHT/SUNDAY -- AND ACCOMPANYING HEIGHT FALLS QUICKLY MOVES THROUGH THE INTERMOUNTAIN WEST/NORTHERN ROCKIES. LATTER FEATURE ASSOCIATED WITH 300MB/ACARS INDICATED 100KT-120KT JET CORE FROM THE PACIFIC NORTHWEST INTO THE CENTRAL GREAT BASIN AREA. LATEST SURFACE ANALYSIS SHOWING QUASI-STATIONARY FRONTAL BOUNDARY EXTENDING FROM SOUTHERN MONTANA INTO NORTHEAST WYOMING AND THE NEBRASKA PANHANDLE...WHILE LEADING EDGE OF ARCTIC FRONT PLUNGES THROUGH SOUTHWEST KANSAS...CENTRAL OKLAHOMA...AND NORTHERN ARKANSAS. QUESTION ULTIMATELY COMES DOWN TO HOW MUCH SNOW PORTIONS OF THE CWA WILL RECEIVE TONIGHT AND SUNDAY. NATURE OF COLD AIRMASS AND DENDRITIC CONSIDERATIONS WOULD SUGGEST A GOOD SNOW EFFICIENCY AS SNOW TO LIQUID WATER EQUIVALENTS MAY BE IN THE 15:1 TO 20:1 RANGE. BELIEVE THERE IS ALSO POTENTIAL FOR BANDING INTO PORTIONS OF THE SOUTHWEST CWA GIVEN ORIENTATION AND DEGREE OF LOW TO MID FRONTOGENETICAL FORCING... UPPER JET STREAK...AND OUTSIDE POSSIBILITIES FOR CONVECTIVE ENHANCEMENT. GIVEN THIS...SNOWFALL RATES AROUND/IN EXCESS OF 1 INCH/HOUR NOT OUT OF THE QUESTION OVERNIGHT AND EARLY SUNDAY MORNING IN THE SOUTHWEST CWA. IN ALL...INCLINATIONS ARE STORM TOTAL 4 TO 6 INCHES (MAYBE LOCALLY TO 7 INCHES ALONG AND WEST OF HWY 183 IN NCNTRL KS?) ROUGHLY SOUTHWEST OF A LINE FROM BEAVER CITY...TO SMITH CENTER...TO BELOIT. COULD BE CLOSE CALL ON WARNING CRITERIA...BUT THINK MOST OF THE AREAS IN THE SOUTHWEST CWA WILL FALL SHORT OF WARNING THRESHOLD. FROM THERE... WOULD THEN EXPECT A NARROW CORRIDOR OF 3 TO 5 INCHES...TRAILING OFF TO 1 TO 3 INCHES OR SO FOR THE TRI-CITIES. NORTHEAST CWA STANDS TO SEE ONLY MINIMAL ACCUMULATIONS. SHORT RANGE ENSEMBLES /BASED AT 9Z/ AND LATEST RUC20/DEVELOPMENTAL RUC20 REAFFIRM THEORY OF MAX SNOW AMOUNTS BEING FAR ENOUGH SOUTH OUT OF THE CWA. SHOULD ALSO MENTION THAT GUSTY NE/N WINDS WILL BE AN ADDITIONAL NUISANCE FACTOR... ESPECIALLY IN THE SOUTHWEST CWA. THE SNOW IS EXPECTED TO PERSIST THROUGH THE EARLY/MID MORNING HOURS OF SUNDAY...BEFORE TAPERING TO FLURRIES DURING THE AFTERNOON. WINDS WILL BEGIN TO DIE DOWN AS WELL THROUGH SUNDAY AFTERNOON/EARLY EVENING. IN THE OUTER PERIODS...MEDIUM RANGE MODELS/ENSEMBLES IN REASONABLY GOOD AGREEMENT WITH COLD VORTEX SHIFTING EASTWARD THROUGH EASTERN CANADA BY THE MIDDLE OF THE WEEK...WHILE SPLIT FLOW/MEAN TROUGH THROUGH THE WESTERN CONUS. GOING SNOW CHANCES LATE TUE/WED/THU ARE STILL REASONABLE AND WILL BE MAINTAINED...BUT THINK ENTIRELY POSSIBLE THAT BULK OF PRECIP/BEST CHANCES COULD END UP BEING WELL SOUTH OF THE AREA GIVEN EXPECTED ORIENTATION OF SUBTROPICAL JET AND/OR CUT-OFF NATURE OF SOUTHWEST CONUS TROUGH. COORDINATED WITH LBF...DDC AND ICT. .GID...WINTER WEATHER ADVISORY OVERNIGHT AND SUNDAY MORNING FOR DAWSON...GOSPER...PHELPS...KEARNEY...FURNAS...HARLAN... FRANKLIN...AND WEBSTER COUNTIES IN SOUTH CENTRAL NEBRASKA. WINTER WEATHER ADVISORY OVERNIGHT AND SUNDAY MORNING FOR PHILLIPS...SMITH...JEWELL...ROOKS...OSBORNE...AND MITCHELL COUNTIES IN NORTH CENTRAL KANSAS. GUYER ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 1004 PM EST SAT FEB 21 2003 LARGE PRECIP SHIELD CONTINUES TO WORK NORTH AND EAST IN ADVANCE OF THE SURFACE LOW AS OF THIS WRITING...WITH THE PCPN SHOWING A DEFINITE CONVECTIVE ("SHOWERY") APPEARANCE SOUTH AND EAST OF A TRENTON ONT-HAMILTON ONT-POINT PELEE ONT LINE...AND A DEFINITE STRATIFORM SIGNATURE TO THE NORTH OF THIS LINE. WITHOUT LOOKING AT THE SURFACE OBS...ONE WOULD EXPECT THAT THIS DEMARCATION LINE WOULD ROUGHLY COINCIDE WITH THE CHANGEOVER FROM R-/ZR- TO SN...AND THE 02Z OBS DO IN FACT BEAR THIS OUT. SOME OF THE ELEVATED CONVECTION WORKING ACROSS THE AREA HAS PRODUCED NUMEROUS REPORTS OF THUNDER IN OUR CWA THIS EVENING...WITH REPORTS OF SOME RUMBLES ALREADY AS FAR NORTH AND EAST AS MONROE...WAYNE...AND EVEN OSWEGO COUNTIES! COMPARING THE LATEST SURFACE ANALYSES WITH THE INITIAL FRAMES OF THE 00Z ETA RUN SHOWS GOOD AGREEMENT ON THE CURRENT POSITION OF THE SURFACE LOW. IN ADDITION...3 HR PRESSURE CHANGE ANALYSES FROM MSAS SHOW THE GREATEST FALLS ALONG A KJHW-KYTR AXIS AT THIS TIME...JUST SLIGHTLY WEST OF THE PROJECTED TRACK OF THE LOW. GIVEN THE GENERALLY GOOD HANDLE THE ETA APPEARS TO HAVE ON THINGS AT THIS TIME...AS WELL AS THE CURRENT RADAR IMAGERY AND SURFACE OBS...I FEEL THAT THE CURRENT FORECAST CAPTURES THE SITUATION FAIRLY WELL AND WILL THEREFORE NOT BE MAKING MUCH IN THE WAY OF CHANGES WITH THIS NEXT UPDATE. ABOUT THE ONLY THINGS OF NOTE THAT I'LL DO ARE REFRESH THE WIND WORDING AND CHANGE THE TONE OF THE FORECAST OVER SOME OF MY CENTRAL/EASTERN ZONES TO INDICATE A REDEVELOPMENT OF THE PCPN A LITTLE LATER TONIGHT...THAT'S ABOUT ALL. THE CURRENT WSW ALSO HAS GOOD HANDLE ON THINGS...SO WHILE THIS WILL BE REISSUED IT WILL MERELY BE AN UPDATE TO THE PREVIOUS STATEMENT. IT SHOULD BE NOTED THAT WE'VE ALREADY SEEN 1/4" OF ICE ACCUMULATION UP AT WELLESLEY ISLAND AS OF 945 PM...AND WITH PLENTY MORE -FZRA ON THE WAY OVERNIGHT...CONFIDENCE IS HIGH THAT WE SHOULD BE ABLE TO ULTIMATELY VERIFY THE WARNING FOR JEFFERSON/LEWIS COUNTIES. AS FOR THE FLOOD WATCH FOR ERIE COUNTY...WITH 0.40" OF LIQUID ALREADY HAVING FALLEN AT KBUF AND MORE STILL ON THE WAY WITH THE NEXT ROUND OF CONVECTION...I CAN'T RULE OUT ANY FLOODING SO WE WILL OPT TO KEEP THAT GOING...THE MID SHIFT MAY BE ABLE TO DROP THIS WITH THE MORNING PACKAGE. THE PREVIOUS 2 AFDS FOLLOW BELOW...ZONES SHOULD BE OUT BY 1030 OR SO...WITH UPDATED STATEMENTS TO FOLLOW. ****** 703 PM AFD ****** DIFFICULT DECISIONS ABOUND HERE THIS EVENING...AS WE ARE LITERALLY LIVING ON THE EDGE PRECIP-WISE ACROSS THE NIAGARA FRONTIER/NORTHERN GENESEE VALLEY. SURFACE OBS AS WELL AS MESONET DATA INDICATE THAT TEMPERATURES HAVE DROPPED TO AROUND OR JUST BELOW FREEZING AS OF 23Z IN A NORTHEASTERLY FLOW...INDUCING SOME -SN TO MIX IN WITH THE RAIN AT KBUF...KROC...AND KIAG. A PRELIMINARY LOOK AT THE 00Z KBUF SOUNDING AS ITS COMING IN SHOWS THE FREEZING LEVEL CURRENTLY SITTING AT ABOUT 1.5 KFT...WITH A SHALLOW COLD POCKET IMMEDIATELY BELOW...THEN WARMING BELOW THAT TO THE SURFACE. TO OUR WEST...TEMPERATURES HAVE DROPPED TO SLIGHTLY BELOW FREEZING...WITH KYHM NOW REPORTING FREEZING RAIN. WITH TEMPS DROPPING TO CRITICAL VALUES ALREADY...AND THE NE FLOW EXPECTED TO PERSIST...CLIMATOLOGY AND PAST EXPERIENCE WOULD SUGGEST MORE OF A POTENTIAL FOR MIXED PRECIP ACROSS THE IAG FRONTIER/ROC AREA THIS EVENING THAN JUST PLAIN RAIN. ALARMINGLY...THE 18Z ETA SUGGESTS ADDITIONAL SLIGHT COOLING AT THE SURFACE/LOW LEVELS TONIGHT WITH SOME WARMING IMMEDIATELY ABOVE AS THE LOW CENTER APPROACHES OUR AREA...SUGGESTING THAT PRECIP WILL BE IN THE FORM OF FREEZING RAIN FOR A WHILE. I'M NOT SURE AT THIS TIME THAT THE ADDITIONAL COOLING WILL MATERIALIZE GIVEN THE RELATIVELY CLOSE TRACK OF THE LOW...ESPECIALLY WITH HEAVIER PCPN MOVING IN WHICH *MAY* HELP TO DRAG SOME WARMER AIR ALOFT BACK DOWN TO THE SURFACE. STILL...I CAN'T IGNORE WHAT'S ALREADY HAPPENING RIGHT NOW AS WELL AS MY PERSONAL INTUITION...SO WE WILL OPT TO ISSUE EXTEND THE WINTER WEATHER ADVISORY INTO THIS EVENING FOR NIAGARA...ERIE...ORLEANS...GENESEE ...AND MONROE COUNTIES BECAUSE OF THE POTENTIAL FOR MIXED PRECIP. AT THIS TIME WILL CALL IT A MIX OF RAIN AND FREEZING RAIN WITH A LITTLE SNOW...CHANGING OVER TO SLEET AND THEN SNOW LATER TONIGHT AS PER THE GOING FORECAST. THE OTHER ISSUE WE WILL HAVE TO CONTEND WITH IS SOME ELEVATED CONVECTION. LIGHTNING PLOTS HAVE BEEN SHOWING CLOUD TO GROUND STRIKES ALONG A LINE FROM EASTERN KENTUCKY UP INTO NORTHWESTERN PA LATE THIS AFTERNOON AND EARLY EVENING...ALONG AN AXIS OF STRONG 925 MB MOISTURE CONVERGENCE AND MARGINAL LI'S IN THE 925-850 MB LAYER AS DEPICTED BY THE 18Z ETA. AS THE ETA LIFTS THIS FORCING AND INSTABILITY ACROSS OUR SOUTHERN AND EASTERN ZONES TONIGHT...I WILL ALSO THROW IN A MENTION OF THUNDER AS FOR OUR SOUTHERN TIER/SOUTHERN GENESEE VALLEY/EASTERN FINGER LAKES/PART OF THE NORTH COUNTRY. INDEED...AS I HAVE BEEN TYPING THIS KJHW HAS REPORTED THUNDER...AS HAVE A COUPLE OF SPOTTERS ACROSS THE SOUTHERN TIER...SO THIS TWEAK I'M GONNA MAKE LOOKS EVEN BETTER NOW. THIS AFTERNOON'S AFD FOLLOWS BELOW...HOPEFULLY WE SHOULD HAVE THE FORECAST UPDATED SOMETIME IN THE NEXT HALF HOUR OR SO...WHICH IN TURN WILL BE FOLLOWED BY AN UPDATED WSW. DUE TO THE THIN LINE WE ARE WALKING WEATHER-WISE...THIS NEW FORECAST COULD BE SUBJECT TO ADDITIONAL SIGNIFICANT CHANGES LATER ON THIS EVENING...SO STAY TUNED. ******* 300 PM AFD ******* THE TEMPERATURE HAS DROPPED BACK TO BELOW FREEZING AT FORT DRUM AND WE HAVE REPORTS OF FREEZING RAIN AND 29 DEGREES ON THE ST LAWRENCE RIVER. WITH THE NORTHEAST FLOW CONTINUING IT IS LIKELY THAT THE FREEZING RAIN WILL WORK IT'S WAY FURTHER SOUTH. RAIN AMOUNTS LOOK TO BE OVER .5 OVER JEFFERSON AND LEWIS COUNTIES BEFORE THE CHANGE TO SNOW SUNDAY MORNING, SO WE WILL HOIST A WINTER STORM WARNING FOR ICE TONIGHT AND CONTINUE IT INTO SUNDAY. WE EXPECT 4 TO 7 INCHES OF SNOW ON TOP OF THE ICE BEFORE IT TAPERS OFF LATE SUNDAY AFTERNOON. THE FLOOD WATCH HAS BEEN CONTINUED IN ERIE COUNTY FOR ICE JAMS, DUE TO MODERATE RAIN THIS AFTERNOON AND OVERNIGHT, THOUGH WITH TEMPERATURES IN THE MID 30S THERE SHOULD BE LITTLE RUNOFF ADDED DUE TO MELTING. ELSEWHERE THE PRECIPITATION SHOULD BE RAIN TONIGHT AND CHANGE TO SLEET BEFORE GOING TO SNOW -- LATE TONIGHT IN THE WEST AND AROUND 9 AM IN OSWEGO COUNTY. SNOW AMOUNTS ARE KEPT IN THE 3 TO 6 INCH RANGE IN THE LOBE HANGING BACK BEHIND THE LOW, SO WE WILL RETAIN THE ADVISORIES FOR LATE TONIGHT AND SUNDAY. THE WINDS WILL PICK UP IN THE AFTERNOON, AND MAKE FOR TREACHEROUS DRIVING IN THE BLOWING AND DRIFTING SNOW. THE ETA AND RUC MODELS SHOW SOME LAKE EFFECT DEVELOPING SUNDAY EVENING AFTER THE MAIN SNOW AREA WITHDRAWS, BUT THE STRONG INVERSION IS AT 5000 FEET AND DROPPING, SO WE WILL KEEP LIKELY POPS TO THE SOUTHEAST OF LAKE ONTARIO. ANOTHER WEAK LOW CROSSES THE AREA MONDAY WITH ONLY AN INCH OR SO EXPECTED. THE MRF SHOWS MIXED PRECIPITATION POSSIBLE AGAIN FRIDAY, BUT WITH THE VARIATION OF SOLUTIONS AS WE APPROACH, WE WILL CALL IT SNOW OR RAIN AT THIS TIME. .BUF...FLOOD WATCH OVERNIGHT NYZ010 WINTER WEATHER ADVISORY OVERNIGHT AND SUNDAY NYZ001>003-010-011 WINTER WEATHER ADVISORY OVERNIGHT AND SUNDAY NYZ012>014-019>021 WINTER WEATHER ADVISORY SUNDAY NYZ004>006 WINTER STORM WARNING OVERNIGHT AND SUNDAY NYZ007-008 $$ JJR ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 703 PM EST SAT FEB 21 2003 DIFFICULT DECISIONS ABOUND HERE THIS EVENING...AS WE ARE LITERALLY LIVING ON THE EDGE PRECIP-WISE ACROSS THE NIAGARA FRONTIER/NORTHERN GENESEE VALLEY. SURFACE OBS AS WELL AS MESONET DATA INDICATE THAT TEMPERATURES HAVE DROPPED TO AROUND OR JUST BELOW FREEZING AS OF 23Z IN A NORTHEASTERLY FLOW...INDUCING SOME -SN TO MIX IN WITH THE RAIN AT KBUF...KROC...AND KIAG. A PRELIMINARY LOOK AT THE 00Z KBUF SOUNDING AS ITS COMING IN SHOWS THE FREEZING LEVEL CURRENTLY SITTING AT ABOUT 1.5 KFT...WITH A SHALLOW COLD POCKET IMMEDIATELY BELOW...THEN WARMING BELOW THAT TO THE SURFACE. TO OUR WEST...TEMPERATURES HAVE DROPPED TO SLIGHTLY BELOW FREEZING...WITH KYHM NOW REPORTING FREEZING RAIN. WITH TEMPS DROPPING TO CRITICAL VALUES ALREADY...AND THE NE FLOW EXPECTED TO PERSIST...CLIMATOLOGY AND PAST EXPERIENCE WOULD SUGGEST MORE OF A POTENTIAL FOR MIXED PRECIP ACROSS THE IAG FRONTIER/ROC AREA THIS EVENING THAN JUST PLAIN RAIN. ALARMINGLY...THE 18Z ETA SUGGESTS ADDITIONAL SLIGHT COOLING AT THE SURFACE/LOW LEVELS TONIGHT WITH SOME WARMING IMMEDIATELY ABOVE AS THE LOW CENTER APPROACHES OUR AREA...SUGGESTING THAT PRECIP WILL BE IN THE FORM OF FREEZING RAIN FOR A WHILE. I'M NOT SURE AT THIS TIME THAT THE ADDITIONAL COOLING WILL MATERIALIZE GIVEN THE RELATIVELY CLOSE TRACK OF THE LOW...ESPECIALLY WITH HEAVIER PCPN MOVING IN WHICH *MAY* HELP TO DRAG SOME WARMER AIR ALOFT BACK DOWN TO THE SURFACE. STILL...I CAN'T IGNORE WHAT'S ALREADY HAPPENING RIGHT NOW AS WELL AS MY PERSONAL INTUITION...SO WE WILL OPT TO ISSUE EXTEND THE WINTER WEATHER ADVISORY INTO THIS EVENING FOR NIAGARA...ERIE...ORLEANS...GENESEE ...AND MONROE COUNTIES BECAUSE OF THE POTENTIAL FOR MIXED PRECIP. AT THIS TIME WILL CALL IT A MIX OF RAIN AND FREEZING RAIN WITH A LITTLE SNOW...CHANGING OVER TO SLEET AND THEN SNOW LATER TONIGHT AS PER THE GOING FORECAST. THE OTHER ISSUE WE WILL HAVE TO CONTEND WITH IS SOME ELEVATED CONVECTION. LIGHTNING PLOTS HAVE BEEN SHOWING CLOUD TO GROUND STRIKES ALONG A LINE FROM EASTERN KENTUCKY UP INTO NORTHWESTERN PA LATE THIS AFTERNOON AND EARLY EVENING...ALONG AN AXIS OF STRONG 925 MB MOISTURE CONVERGENCE AND MARGINAL LI'S IN THE 925-850 MB LAYER AS DEPICTED BY THE 18Z ETA. AS THE ETA LIFTS THIS FORCING AND INSTABILITY ACROSS OUR SOUTHERN AND EASTERN ZONES TONIGHT...I WILL ALSO THROW IN A MENTION OF THUNDER AS FOR OUR SOUTHERN TIER/SOUTHERN GENESEE VALLEY/EASTERN FINGER LAKES/PART OF THE NORTH COUNTRY. INDEED...AS I HAVE BEEN TYPING THIS KJHW HAS REPORTED THUNDER...AS HAVE A COUPLE OF SPOTTERS ACROSS THE SOUTHERN TIER...SO THIS TWEAK I'M GONNA MAKE LOOKS EVEN BETTER NOW. THIS AFTERNOON'S AFD FOLLOWS BELOW...HOPEFULLY WE SHOULD HAVE THE FORECAST UPDATED SOMETIME IN THE NEXT HALF HOUR OR SO...WHICH IN TURN WILL BE FOLLOWED BY AN UPDATED WSW. DUE TO THE THIN LINE WE ARE WALKING WEATHER-WISE...THIS NEW FORECAST COULD BE SUBJECT TO ADDITIONAL SIGNIFICANT CHANGES LATER ON THIS EVENING...SO STAY TUNED. ***** PREVIOUS AFD ******* THE TEMPERATURE HAS DROPPED BACK TO BELOW FREEZING AT FORT DRUM AND WE HAVE REPORTS OF FREEZING RAIN AND 29 DEGREES ON THE ST LAWRENCE RIVER. WITH THE NORTHEAST FLOW CONTINUING IT IS LIKELY THAT THE FREEZING RAIN WILL WORK IT'S WAY FURTHER SOUTH. RAIN AMOUNTS LOOK TO BE OVER .5 OVER JEFFERSON AND LEWIS COUNTIES BEFORE THE CHANGE TO SNOW SUNDAY MORNING, SO WE WILL HOIST A WINTER STORM WARNING FOR ICE TONIGHT AND CONTINUE IT INTO SUNDAY. WE EXPECT 4 TO 7 INCHES OF SNOW ON TOP OF THE ICE BEFORE IT TAPERS OFF LATE SUNDAY AFTERNOON. THE FLOOD WATCH HAS BEEN CONTINUED IN ERIE COUNTY FOR ICE JAMS, DUE TO MODERATE RAIN THIS AFTERNOON AND OVERNIGHT, THOUGH WITH TEMPERATURES IN THE MID 30S THERE SHOULD BE LITTLE RUNOFF ADDED DUE TO MELTING. ELSEWHERE THE PRECIPITATION SHOULD BE RAIN TONIGHT AND CHANGE TO SLEET BEFORE GOING TO SNOW -- LATE TONIGHT IN THE WEST AND AROUND 9 AM IN OSWEGO COUNTY. SNOW AMOUNTS ARE KEPT IN THE 3 TO 6 INCH RANGE IN THE LOBE HANGING BACK BEHIND THE LOW, SO WE WILL RETAIN THE ADVISORIES FOR LATE TONIGHT AND SUNDAY. THE WINDS WILL PICK UP IN THE AFTERNOON, AND MAKE FOR TREACHEROUS DRIVING IN THE BLOWING AND DRIFTING SNOW. THE ETA AND RUC MODELS SHOW SOME LAKE EFFECT DEVELOPING SUNDAY EVENING AFTER THE MAIN SNOW AREA WITHDRAWS, BUT THE STRONG INVERSION IS AT 5000 FEET AND DROPPING, SO WE WILL KEEP LIKELY POPS TO THE SOUTHEAST OF LAKE ONTARIO. ANOTHER WEAK LOW CROSSES THE AREA MONDAY WITH ONLY AN INCH OR SO EXPECTED. THE MRF SHOWS MIXED PRECIPITATION POSSIBLE AGAIN FRIDAY, BUT WITH THE VARIATION OF SOLUTIONS AS WE APPROACH, WE WILL CALL IT SNOW OR RAIN AT THIS TIME. .BUF...FLOOD WATCH TONIGHT NYZ010 WINTER WEATHER ADVISORY TONIGHT AND SUNDAY NYZ001>003-010-011 WINTER WEATHER ADVISORY LATE TONIGHT AND SUNDAY NYZ012>014-019>021 WINTER WEATHER ADVISORY SUNDAY NYZ004>006 WINTER STORM WARNING TONIGHT AND SUNDAY NYZ007-008 $$ JJR/APB ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 300 PM EST SAT FEB 21 2003 THE TEMPERATURE HAS DROPPED BACK TO BELOW FREEZING AT FORT DRUM AND WE HAVE REPORTS OF FREEZING RAIN AND 29 DEGREES ON THE ST LAWRENCE RIVER. WITH THE NORTHEAST FLOW CONTINUING IT IS LIKELY THAT THE FREEZING RAIN WILL WORK IT'S WAY FURTHER SOUTH. RAIN AMOUNTS LOOK TO BE OVER .5 OVER JEFFERSON AND LEWIS COUNTIES BEFORE THE CHANGE TO SNOW SUNDAY MORNING, SO WE WILL HOIST A WINTER STORM WARNING FOR ICE TONIGHT AND CONTINUE IT INTO SUNDAY. WE EXPECT 4 TO 7 INCHES OF SNOW ON TOP OF THE ICE BEFORE IT TAPERS OFF LATE SUNDAY AFTERNOON. THE FLOOD WATCH HAS BEEN CONTINUED IN ERIE COUNTY FOR ICE JAMS, DUE TO MODERATE RAIN THIS AFTERNOON AND OVERNIGHT, THOUGH WITH TEMPERATURES IN THE MID 30S THERE SHOULD BE LITTLE RUNOFF ADDED DUE TO MELTING. ELSEWHERE THE PRECIPITATION SHOULD BE RAIN TONIGHT AND CHANGE TO SLEET BEFORE GOING TO SNOW -- LATE TONIGHT IN THE WEST AND AROUND 9 AM IN OSWEGO COUNTY. SNOW AMOUNTS ARE KEPT IN THE 3 TO 6 INCH RANGE IN THE LOBE HANGING BACK BEHIND THE LOW, SO WE WILL RETAIN THE ADVISORIES FOR LATE TONIGHT AND SUNDAY. THE WINDS WILL PICK UP IN THE AFTERNOON, AND MAKE FOR TREACHEROUS DRIVING IN THE BLOWING AND DRIFTING SNOW. THE ETA AND RUC MODELS SHOW SOME LAKE EFFECT DEVELOPING SUNDAY EVENING AFTER THE MAIN SNOW AREA WITHDRAWS, BUT THE STRONG INVERSION IS AT 5000 FEET AND DROPPING, SO WE WILL KEEP LIKELY POPS TO THE SOUTHEAST OF LAKE ONTARIO. ANOTHER WEAK LOW CROSSES THE AREA MONDAY WITH ONLY AN INCH OR SO EXPECTED. THE MRF SHOWS MIXED PRECIPITATION POSSIBLE AGAIN FRIDAY, BUT WITH THE VARIATION OF SOLUTIONS AS WE APPROACH, WE WILL CALL IT SNOW OR RAIN AT THIS TIME. .BUF...FLOOD WATCH TONIGHT NYZ010 WINTER WEATHER ADVISORY LATE TONIGHT AND SUNDAY NYZ001>003-010>014-019>021 WINTER WEATHER ADVISORY SUNDAY NYZ004>006 WINTER STORM WARNING TONIGHT AND SUNDAY NYZ007-008 $$ APB ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 850 PM EST SAT FEB 22 2003 WL UPDATE TO INDICATE SVR THREAT OVR. RAIN AND FEW TSTMS CONTINUING. GRADIENT WNDS OVR LAND RUNNING 15 TO 20 KTS...LTL HIER NR THE CSTL SXNS. RUC SHOWG DP LYRD MSTR DCRSG BY SR SO SHUD CONT SUM CLDS IN THE MORNING WITH CLRG IN THE AFTN TMRW. SFC LO OVR KY LIFTG OUT BUT GRAD WL RMN TITE THRU THE NGT. SFC FNT TO GO THRU AFT SR. NATL RADAR SHWG SHWRS WI FROPA SO WL CONT CHC OR SLGT CHC TIL SR. MARINE: BUSY/HECTIC NIGHT. AFTER 2 RADIOSONDE (AND/OR BALLOONS) RUNS ZAPPED BY LIGHTENING...WILL NEED TO BE BRIEF. STRONG LOW PRESSURE CURRENTLY OVER WEST VIRGINIA WILL CONTINUE TO INTENSIFY AND RACE TO THE NE TONIGHT INTO SUNDAY. STRONG SW P-GRAD WILL PRODUCE STORM FORCE WINDS OF 45 TO 50 KTS FROM OREGON INLET SOUTH TO CAPE LOOKOUT TONIGHT. GALE FORCE SW WINDS OF 40-45 KTS WILL ENCOMPASS SOUND WATERS AS WELL AS OCEAN WATERS NORTH OF OREGON INLET...AND SOUTH OF CAPE LOOKOUT TO NORTH OF SURF CITY. WINDS VEER TO W SUNDAY AS THE LOW MOVES INTO THE NORTHEASTERN STATES THUS DRAGGING A COLD FRONT THROUGH OUR AREA. WINDS REMAIN WESTERLY THEN EVENTUALLY DIMINISH AS HIGH PRESSURE BUILDS INTO THE AREA. THE STRONG WINDS WILL BUILD SOUND WAVES TO 4 FT. SEAS GO TO 13-16 FT. SEAS SLOWLY SUBSIDE SUNDAY AFTERNOON. MINOR SOUNDSIDE FLOODING A THREAT WITH THE STRONG SW-W FLOW. HEAVY SURF ADVISORIES ARE IN EFFECT FOR MAINLY SOUTH FACING BEACHES FROM SOUTH OF CAPE HATTERAS TO NORTH OF SURF CITY. WAVES IN THESE SURF ZONES WILL REACH BETWEEN 8 AND 12 FEET LATER TONIGHT INTO SUNDAY MORNING. THE VERY ROUGH SURF AND STRONG ONSHORE WINDS WILL LIKELY PRODUCE MODERATE TO SEVERE BEACH EROSION ALONG SOUTH FACING BEACHES... ESPECIALLY AROUND HIGH TIDE WHICH OCCURS NEAR MIDNIGHT TONIGHT. NEXT COLD FRONT APPROACHES CWF AREA MONDAY AND SWEEPS THROUGH MONDAY NIGHT. HIGH PRESSURE THEN BUILDS IN THROUGH MID WEEK AS YET ANOTHER SOUTHERN STREAM LOW PRESSURE SYSTEM APPROACHES CWF AREA THURSDAY. .MHX...STORM WARNING CAPE LOOKOUT TO S OF OREGON INLET. ...GALE WARNING REMAINDER OF COASTAL WATERS AND SOUNDS. ...WIND ADVISORY TONIGHT FOR S COAST. ...HIGH WIND WARNING TONIGHT FOR OUTER BANKS. CGG/GC nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 930 PM CST SAT FEB 22 2003 THE WINTER STORM WARNING AREA HAS BEEN KEPT AS IT WAS BUT EXTENDED TO COVER PART OF SUNDAY AFTERNOON. IT APPEARS THAT THE SNOW WILL NOT ALL BE DONE BY NOON...ESPECIALLY IN AREAS IMMEDIATELY WEST OF THE ARKANSAS RIVER IN NORTH CENTRAL OK. ADDITIONALLY...A SNOW ADVISORY WAS ADDED ON THE WESTERN AND SOUTHWESTERN PERIPHERY. THIS WAS DONE AFTER A QUICK INSPECTION OF THE RUC AND COORDINATING WITH AMA. .OUN... OK...WINTER STORM WARNING EFFECTIVE LATE TONIGHT THROUGH SUNDAY AFTERNOON FOR ZONES OKZ005>008...OKZ012>013. SNOW ADVISORY EFFECTIVE LATE TONIGHT THROUGH SUNDAY MORNING ZONES 004-009>011. TX...NONE. ok EASTERN OKLAHOMA/NORTHWEST ARKANSAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE TULSA OKLAHOMA 1015 AM CST SAT FEB 22 2003 PRECIP HAS ENDED ACROSS NORTHWEST/WEST CENTRAL ARKANSAS AS UPPER STORM SYSTEM CONTINUES TO SHIFT EASTWARD. LOW LEVEL COLD ADVECTION BEHIND DEPARTING SYSTEM HAS MAINTAINED BROAD LOW CLOUD DECK. CLOUD DECK IS LIKELY SHALLOW HOWEVER LATEST RUC MAINTAINS GOOD COLD ADVECTION INTO THE AFTERNOON...SO DESPITE NEWEST GUIDANCE...WILL UPDATE FORECAST TO REFLECT CLOUDY/MOSTLY CLOUDY DAY FOR CENTRAL AND NORTHERN ZONES. TEMPS WILL BE DROPPED ONE-TWO CATEGORIES ESPECIALLY ACROSS FAR NE OK/NW AR. FORECAST ID= 07 .TSA... AR...NONE. OK...WINTER STORM WATCH FOR SUNDAY FOR ZONES OKZ054>058. ok AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 1103 AM MST SAT FEB 22 2003 CURRENT SURFACE MAP SHOWS SHALLOW ARCTIC BOUNDARY WELL SOUTH AND WEST OF THE REGION. LOW PRESSURE ALONG THE BOUNDARY IS LOCATED IN CENTRAL WY. ONE SHRTWV IS PASSING THRU THE DAKOTAS WITH BAND OF LIGHT SNOW MOVING ACROSS EASTERN CWA AT THIS TIME. NEXT WAVE MOVING THRU WY WITH SHIELD OF PCPN MOVING ACROSS SOUTHERN MT AND MUCH OF WY. COLDER AIR IS SLOWLY MAKING ITS WAY INTO NORTHEAST WY AND THE HILLS...BUT PROBABLY NOT IN EARNEST UNTIL LATER TODAY AND TONIGHT AS DEEPER LAYER OF COLD AIR SETTLES IN. SNOW WILL REDEVELOP ACROSS NORTHEAST WY AND THE HILLS THIS AFT. MAIN CONCERN FOR LATER TODAY AND TONIGHT IS WHERE BAND OF HEAVIER SNOW WILL TRACK AS WAVE MOVES INTO CENTRAL PLAINS THIS EVE. 12Z MODELS IN PRETTY GOOD AGREEMENT ON MOVING THIS BAND SOUTHEASTWARD ACROSS NORTHEAST WY AND THRU FAR SOUTHWEST SD AND NEBRASKA PANHANDLE THIS EVENING. ETA KEEPS HEAVIEST SNOW SOUTH OF THE CWA WHILE GFS BRINGS AROUND A QUARTER INCH QPF TO SOUTHERN CAMPBELL AND WESTON COUNTIES ...AS WELL AS EXTREME SOUTHWEST SD. LATEST RUC ALSO BRINGS PCPN BAND A BIT FURTHER NORTH. AS SURFACE LOW DEVELOPS IN EASTERN CO LATER TODAY. WILL TEND TO FOLLOW CLOSER TO ETA SOLUTION AT THIS TIME AS IT HAS SEEMED TO HANDLE THIS EVENT RATHER WELL SO FAR...BUT THIS WILL HAVE TO BE MONITORED CLOSELY. HAVE UPDATED ZONES TO GO WITH OCCASIONAL LIGHT SNOW ACROSS WESTERN SD PLAINS WITH AN INCH OR LESS ACCUMULATION...WITH SNOW REDEVELOPING ACROSS THE WESTERN ZONES THIS AFT. ALSO UPDATED TONIGHTS ZONES TO GO WITH HIGHER POPS OVER NORTHEAST WY...THE HILLS...AND FAR SOUTHWEST SD. LOWERED HIGH TEMPS FOR TODAY AS DO NOT EXPECT MUCH OF AN INCREASE FROM WHERE TEMPS ARE RIGHT NOW. MADE SOME MINOR ADJUSTMENTS TO WINDS AS WELL. .UNR...NONE. $$ ST sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AMARILLO TX 1010 PM CST SAT FEB 22 2003 UPDATED FIRST AND SECOND PERIODS OF FORECAST PACKAGE TO HIT SNOW POTENTIAL ACROSS THE NORTHEAST ZONES A LITTLE MORE...INCLUDING ISSUING A SNOW ADVISORY FROM MIDNIGHT TO NOON SUNDAY FOR BEAVER AND LIPSCOMB COUNTIES. LATEST RUC AND MESOETA INDICATING THAT AROUND ONE-QUARTER OF AN INCH OF QPF MAY FALL ACROSS PORTION OF THE AFOREMENTIONED COUNTIES BY NOON...RESULTING IN AS MUCH AS THREE INCHES OF SNOWFALL. THIS SEEMS REASONABLE CONSIDERING MODERATE UPSLOPE FLOW...MID-LEVEL ISENTROPIC UPGLIDE AND LOW-LEVEL MOISTURE ADVECTION TO THE NORTHEAST OF STRONG BAROCLINIC ZONE STRETCHING FROM SOUTHEASTERN COLORADO INTO THE SOUTHERN TEXAS PANHANDLE. TEMPERATURES AND WINDS WERE ADJUSTED ACCORDINGLY. ZONES WILL BE ISSUED SHORTLY. FCSTID = 08/04 ...PREVIOUS DISCUSSION... LEE TROUGH CONTINUES TO DEEPEN LATE THIS AFTERNOON ACROSS THE EASTERN PLAINS OF COLORADO. SOUTHERLY LOW LEVEL WINDS BEGINNING TO RECOVER. MAIN CONCERN TONIGHT IS SNOW POTENTIAL OVER THE NORTHEAST ZONES. WILL HOLD OFF ON ANY FIRST PERIOD HIGHLIGHTS SINCE THERE IS SOME POTENTIAL THAT PRECIP WON'T BEGIN UNTIL AFTER 06Z AND PRECIP COULD ACTUALLY BEGIN AS -R BEFORE CHANGEOVER TO ALL SNOW BY 12Z SUNDAY MORNING. FIRST PERIOD SYSTEM LOOKS FAIRLY PROGRESSIVE SO THINGS OVER THIS PORTION OF THE HIGH PLAINS SHOULD WIND DOWN BY AROUND 18Z SUNDAY AFTERNOON. ARCTIC AIR CURRENTLY SEEN SLIDING SOUTHWARD ACROSS SOUTHERN NEBRASKA WITH SINGLE DIGIT TEMPS OVER SOUTH DAKOTA. EXPECT SURFACE LOW TO TRACK SOUTHEAST OVER THE PANHANDLES TO NEAR WICHITA FALLS TEXAS BY 12Z SUNDAY MORNING...THIS WILL MAKE WIND FORECAST DIFFICULT. MODELS SUGGEST SOME POTENTIAL FOR SUNSHINE MAINLY OVER THE SOUTHWESTERN ZONES SUNDAY AFTERNOON SO HAVE RETAINED HIGHS IN THE LOWER 40S NEAR HEREFORD BUT ONLY 26 AT BEAVER OK. 1040 HIGH LOOKS TO SPREAD OVER THE SOUTHERN PLAINS MONDAY WITH DECENT LOW LEVEL OVER-RIDING PATTERN TAKING SHAPE. HAVE EXPANDED 20 PERCENTERS MONDAY WITH TEMPS COLD ENOUGH FOR ALL SNOW. MORNING MODELS MAKE THE CASE FOR POPS JUST ABOUT EVERYDAY DURING THIS SEVEN DAY PERIOD. COLDEST DAY LOOKS LIKE MONDAY WITH SOME MINOR REBOUND ON TUESDAY. ETA/GFS BRING ANOTHER SYSTEM ONSHORE OVER CALIFORNIA MONDAY NIGHT SO HAVE KEPT CHANCE POPS FOR THE TUESDAY NIGHT AND WEDNESDAY PERIODS. .AMA... TX...SNOW ADVISORY THROUGH SUNDAY MORNING TXZ005. OK...SNOW ADVISORY THROUGH SUNDAY MORNING OKZ003. $$ RN/JH tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 342 AM CST SUN FEB 23 2003 MAIN FORECAST CONCERN WILL DEAL WITH WINTER STORM MOVING THROUGH THE REGION SUNDAY INTO SUNDAY EVENING. THE STRONG UPPER WAVE FORECAST TO BRING WINTERY WEATHER TODAY SHOWS UP NICELY ON WV IMAGERY AS IT PUSHES TOWARD THE TEXAS PANHANDLE. LEE SIDE SURFACE CYCLOGENESIS WAS OCCURING ALONG THE TX/NM BORDER. IN ADDITION...HIGH PRESSURE AT THE SURFACE WAS HOLDING STRONG ACROSS EASTERN KANSAS AND WESTERN MISSOURI. THE STRENGTH OF THIS HIGH MAY CAUSE THE SURFACE LOW TO TRACK A LITTLE FURTHER SOUTH THAN PREVIOUSLY FORECAST. BOTH 00Z RUNS OF THE ETA AND GFS HAVE CAUGHT ON TO THIS...TRACKING THE LOW FROM THE RED RIVER VALLEY EARLY THIS MORNING...THROUGH ARKANSAS DURING THE DAY...TO THE OHIO RIVER VALLEY BY MONDAY MORNING. LOOKING AT THE 290K SURFACE...VERY STRONG ISENTROPIC LIFT BEGINS AROUND 15Z THIS MORNING ACROSS FAR SOUTHEAST KANSAS AND SOUTHWEST MISSOURI...THEN OVERSPREADS THE REGION TOWARD THE NOON HOUR. THE FLOW ON THIS SURFACE STRENGTHENS DURING THE AFTERNOON...RANGING FROM 30 KTS ACROSS CENTRAL MISSOURI...TO 55 KTS ALONG THE ARKANSAS BORDER. DURING THE EVENING HOURS...290K LIFT CONTINUES OVER THE EASTERN 2/3RD OF THE FORECAST AREA...WITH THE MOST INTENSE LIFT FOUND FAR SOUTHERN MISSOURI. SPECIFIC HUMIDITY VALUES GENERALLY RANGE FROM 2 TO 3 G/KG. WILL HAVE A HARD TIME MEETING THE 12 HOUR DURATION CRITERIA GIVEN IN THE GARCIA METHOD WITH THE FAST MOVMENT OF THE SYSTEM. FEEL THAT TOTALS IN THE HEAVIEST BAND WILL BE CLOSER TO 6 INCHES. HOWEVER...SCATTERED AMOUNTS APPROACHING 8 INCHES ARE NOT OUT OF THE QUESTION...AS THE FORCING ASSOCIATED WITH THIS SYSTEM WILL BE QUITE STRONG. 06Z MESOETA IS CONSISTENT WITH BRINGING A MORE SOUTHERLY TRACK TO THE SYSTEM. WITH THIS IN MIND...LEANING TOWARD EXPANDING THE WARNING FOR A FEW COUNTIES IN FAR SOUTHWEST MISSOURI. LOOKS AS IF INITAL LIFT WILL BE USED UP FOR SATURATING THE COLUMN. THE 06Z MESOETA AND LATEST RUC ARE BOTH SLOWING DOWN THE SYSTEM...SNOW LOOKS TO BEGIN ACROSS SOUTHEAST KANSAS AND FAR WESTERN MISSOURI LATE THIS MORNING...BEFORE AFFECTING THE SPRINGFIELD AREA EARLY THIS AFTERNOON. OUR EASTERN COUNTIES SHOULD SEE SNOW BEGIN BY 3 OR 4 PM. SNOW WILL PERSIST ACROSS MOST OF THE OZARKS THIS EVENING...BEFORE ENDING AFTER MIDNIGHT ACROSS OUR EASTERNMOST COUNTIES. WINDS MAY ALSO BE A FACTOR...ESPECIALLY TONIGHT. MESOETA PRESSURE GRADIENT MAGNITUDES INDICATE GUSTS APPROACHING 30 MPH. THE SGF BUFKIT SOUNDINGS ALSO SHOWS THE POTENTIAL OF 25 TO 30 MPH GUSTS TONIGHT. BUMPED UP LOWS FOR TONIGHT...EVEN WITH ANTICIPATED SNOW COVER...THINK LOW CLOUDS WILL KEEP TEMPERATURES FROM BOTTOMING OUT IN THE SINGLE DIGITS. TRENDED LOWS TOWARD COOLER MAV GUIDANCE AS COMPARED TO THE MET. A SLIGHT CHANCE OF LIGHT WINTERY PRECIPITATION WILL PUSH INTO THE OZARKS REGION BY MONDAY AFTERNOON...AS A MUCH WEAKER UPPER WAVE TRACKS FROM WEST TEXAS TO THE CENTRAL PLAINS. SOME WEAK 850-700 MB Q VECTOR CONVERGENCE AND ISENTROPIC LIFT IS PROGGED TO OVER THE REGION MONDAY AFTERNOON. ADDED 20 POPS FOR LIGHT SNOW FOR THE AFTERNOON. ON TUESDAY...AN UPPER LOW WILL BE FOUND OVER CALIFORNIA WITH BROAD SOUTHWEST UPPER LEVEL FLOW OVER THE SLOWLY RETREATING ARCTIC HIGH. LIGHT SNOW AND OR SLEET WILL BE POSSIBLE TUESDAY AFTERNOON AND NIGHT AS ISENTROPIC UPGLIDE AFFECTS THE REGION. .SGF... MO...WINTER STORM WARNING FOR SUNDAY MORNING THROUGH SUNDAY EVENING FOR ZONES MOZ070>071...MOZ077>083...MOZ088>095...MOZ098...MO101>103. WINTER WEATHER ADVISORY FOR SUNDAY MORNING THROUGH SUNDAY EVENING FOR ZONES MOZ096>097...MOZ101>106. WINTER WEATHER ADVISORY FOR SUNDAY MORNING THROUGH SUNDAY EVENING FOR ZONES MOZ055>058...MOZ066>069. KS...WINTER STORM WARNING FOR SUNDAY MORNING THROUGH SUNDAY EVENING FOR ZONES KSZ097...KSZ101. WINTER WEATHER ADVISORY FOR SUNDAY MORNING THROUGH SUNDAY EVENING FOR ZONE KSZ073. $$ SAW mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1040 AM EST SUN FEB 23 2003 MAIN FORECAST CONCERNS WITH THIS UPDATE ARE LAKE EFFECT SNOWS AND AFTERNOON TEMPERATURES. WATER VAPOR AND RUC/ETA SHOWING A SHORTWAVE...ROTATING THROUGH THE BASE OF A CLOSED LOW OVER NORTHEAST MANITOBA...IS OVER EASTERN UPPER MICHIGAN. ANOTHER MUCH DEEPER SHORTWAVE ROTATING THROUGH THE SAME LOW IS LOCATED OVER SOUTHERN SASKATCHEWAN AND NORTHEAST MONTANA. MORNING RAOBS SHOW THIS SHORTWAVE IS MOVING SLIGHTLY FASTER THAN MODELS PROGGED. GFS IS THE CLOSEST ON THE PROGGED. SURFACE ANALYSIS SHOWING A DEEP LOW MOVING UP THE EASTERN SEABOARD...WHILE A BROAD RIDGE OVER CENTRAL CANADA IS EXPANDING INTO THE NORTHERN PLAINS AND THE UPPER GREAT LAKES. MORNING SOUNDING SHOW THAT THE LAKE-850MB DELTA-T'S ARE AROUND 20C. THIS IS ABOUT A DEGREE OR TWO LESS THAN RUC AND ETA PROJECTED. MUCH OF LAKE SUPERIOR IS ICE COVERED. OPEN AREAS REMAIN OVER THE DEEPER PARTS OF EASTERN LAKE SUPERIOR. VISUAL SATELLITE STILL SHOW LAKE EFFECT SNOW BANDS ACROSS THE CENTRAL LAKE SUPERIOR. KMQT-88D IS DETECTING THE SAME BANDS DEPOSITING LIGHT SNOW OVER MAINLY EASTERN MARQUETTE AND ALGER COUNTIES. A FEW WEAKER BANDS ARE INDICATED OVER SPINE OF THE KEWEENAW PENINSULA SOUTHWEST TO THE PORCUPINE MOUNTAINS. KINL RAOBS SHOWING VERY DRY AIR MASS OVER THE FORECAST AREA. PRECIP WATER AT KINL WAS LESS THAN A TENTH OF AN INCH. IN SPITE OF THE COLD TEMPERATURES...AIR MASS INSTABILITY...AND A NORTH WINDS...THE LAKE EFFECT SNOWS REMAINS LIGHT DUE TO LAKE ICE COVER AND THE DRY AIR. ANTI-CYCLONIC FLOW AHEAD OF THE CANADIAN RIDGE WILL KEEP THE WINDS OUT OF THE NORTH ACROSS THE FORECAST AREA TODAY. DELTA-T'S WILL REMAIN AROUND 20C OVER THE LAKE. THUS LAKE EFFECT SNOW BANDS WILL CONTINUE ACROSS THE LAKE TODAY. THIS WILL PRODUCE BANDS OF CLOUDS ACROSS THE NORTHERN PART OF THE FORECAST AREA AS WELL. SURFACE TRAJECTORY PROGS SHOWING THE AIR MASS OVER EASTERN ONTARIO YESTERDAY IS MOVING OVER THE FORECAST AREA TODAY. TEMPERATURES THERE WERE IN THE SINGLE DIGITS. WITH A LITTLE MORE SUN TODAY OVER THE FORECAST AREA EXPECT A LITTLE WARMER RESULTS. CONDITIONS ARE ALREADY A DEGREE OR TWO WARMER THAN LAMP GUIDANCE. THUS TEMPERATURES A LITTLE BELOW GUIDANCE LOOK REASONABLE...HOWEVER AS THE SUN GETS HIGHER EXPECT TEMPERATURES TO CATCH UP. AS THE SURFACE LOW MEANDERS UP THE EAST COAST...THE WINDS SHOULD WEAKEN OVER THE FORECAST AREA TODAY. ALL IN ALL...IT LOOKS LIKE A FAIRLY DRY DAY FOR THE FORECAST AREA EXCEPT ALONG THE LAKE SUPERIOR SHORE. TEMPERATURES WILL REMAIN COLD...AND WINDS WILL GRADUALLY WEAKEN. .MQT...HEAVY FREEZING SPRAY WARNING E HALF OF LAKE SUPERIOR. DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 202 PM MST SUN FEB 23 2003 FORECAST CONCERNS INCLUDE COLD TEMPERATURES ALONG WITH WHEN AND HOW MUCH TO WARM THEM UP THIS WEEK AS WELL AS INTERMITTENT PRECIPITATION CHANCES THROUGH THURSDAY. 19Z SURFACE MAP ANALYSIS SHOWED A STRONG COLD SURFACE HIGH PRESSURE IN CONTROL OF THE HIGH PLAINS WEATHER FROM SOUTHERN CANADA SOUTHWARD TO SOUTHERN TEXAS. IR AND WATER VAPOR SATELLITE IMAGERY SHOWED A CYCLONIC CIRCULATION TO A WINTER WEATHER SYSTEM THAT PROVIDED OUR SNOWFALL LAST NIGHT NOW OVER THE EASTERN CONUS WITH ANOTHER BROAD TROUGH AND ATTENDANT SHORTWAVE APPROACHING THE WEST COAST. SHORTWAVE IMPULSE IN SOUTHERN WYOMING WAS MOVING TO THE SOUTHEAST IN OUR DIRECTION FOR TONIGHT. MODELS INITIALIZED WELL TODAY WITH POSITION AND STRENGTH OF COLD ARCTIC AIR PENETRATION OVER THE CENTRAL HIGH PLAINS ALONG WITH STRENGTH AND MOVEMENT OF UPPER LEVEL FEATURES ESPECIALLY OUT WEST. WILL GO WITH A COMBINATION OF ETA AMD GFS MODELS THIS FORECAST PACKAGE SINCE AVIATION MODEL TEMPERATURES AT SURFACE AND 850 MB BEST PORTRAYS THE DEEP FREEZE WHICH SHOULD HANG AROUND AT LEAST THROUGH THE MIDDLE OF THE WEEK. THE ETA MODEL WAS A LITTLE BETTER IN HANDLING MOISTURE AND RH IN THE ATMOSPHERE THROUGH THE END OF THE WEEK. FOR TONIGHT MAIN CONCERNS WILL BE HOW LOW TEMPERATURES WILL FALL. CONSIDERING THE LOWER TEMPERATURES OF THIS MORNING AND MEAGER RECOVERY UNDER FULL SUN WILL TWEAK TEMPERATURES TONIGHT DOWN 2 OR 3 DEGREES WHICH IS SLIGHTLY UNDER GUIDANCE. MODELS PROG WINDS TO BE FROM THE NORTH TO NORTHEAST AT 5 TO 10 MPH. WILL GO WITH LOW TEMPERATURES MAINLY IN THE 5 BELOW TO ZERO RANGE MOST AREAS. THIS IS A BLESSING SINCE IF WINDS WERE TO BE STRONGER A WIND CHILL HIGHLIGHT COULD BE IN ORDER. ANOTHER CONCERN IS FOR THE 500 MB SHORTWAVE WHICH MOVES THROUGH THE AREA OUT OF WYOMING. LATEST RUC AND MESOETA MODELS INDICATE SOME MOISTURE TO BE HAD IN THE FORM OF LIGHT SNOW OVERNIGHT. WILL CARRY CHANCE POPS FOR SNOW ALONG WITH MOSTLY CLOUDY SKIES AS THE SHORTWAVE PASSES. THE NEXT WEATHER CHALLENGE INCLUDES THE TIMING AND AMOUNT OF PRECIPITATION EPISODES TUESDAY INTO THURSDAY. ANOTHER WEAK SHORTWAVE MOVES THROUGH THE REGION ON TUESDAY AFTERNOON. MODELS PROG MEAGER DYNAMICS WITH THIS SYSTEM. WILL MAINTAIN LOW CHANCE POPS FOR SNOW. HOW MUCH WILL TEMPERATURES RECOVER IF ANY DURING THE DAY TUESDAY AND WEDNESDAY? THAT IS ANOTHER QUESTION TO PONDER. WITH NO DRASTIC INFLUX OF WARM SOUTH TO SOUTHWEST WINDS AND MAJOR WEATHER SYSTEMS THROUGH TUESDAY WILL GO WITH WARMING ONLY SEVERAL DEGREES. WILL GO A LITTLE UNDER GUIDANCE FOR HIGHS TOMORROW AS MOST OF FORECAST AREA HAS GOOD SNOW COVER. WILL GO WITH HIGH TEMPERATURES MAINLY IN THE 5 TO 10 DEGREE ABOVE ZERO CATEGORY FOR MONDAY FOR TUESDAY WILL CARRY HIGH TEMPERATURES INTO THE TEENS. ALSO WILL MAINTAIN LOW CHANCE POPS FOR SNOW TUESDAY AS YET ANOTHER UPPER LEVEL SHORTWAVE WITH DECENT DYNAMICS MOVES THROUGH THE AREA DURING THE DAY. ON WEDNESDAY A STRONGER MORE POTENT TROUGH AND SHORTWAVE MOVES EASTWARD THROUGH THE CENTRAL HIGH PLAINS. WINDS BECOME MORE UPSLOPE TUESDAY NIGHT INTO WEDNESDAY AS A SURFACE LOW DEVELOPS JUST TO OUR SOUTH. WILL RAISE POPS TUESDAY NIGHT INTO WEDNESDAY WITH HIGHEST POPS OVER THE SOUTH AND LESSER POPS TO THE NORTH. ALSO WITH LOTS OF CLOUDS AROUND AND STILL A GREAT DEAL OF COLD AIR PARKED IN THE NEIGHBORHOOD WILL KEEP TEMPERATURES COLD. EXPECT HIGH TEMPERATURES WEDNESDAY INTO ONLY THE LOWER TO MIDDLE 20S. FOR THE PERIOD THURSDAY THROUGH SUNDAY MRF AND EMCWF MODELS BOTH SHOW CONTINUED SOMEWHAT UNSETTLED WEATHER PATTERN INTO THE WEEKEND. WILL MAINTAIN A CHANCE FOR SNOW ON FRIDAY AS ANOTHER UPPER LEVEL SYSTEM PASSES THROUGH THE REGION. WILL ADD DAY 7 (SUNDAY) WHICH AT THIS TIME APPEARS TO BE PARTLY CLOUDY. WILL KEEP SATURDAY AND SUNDAY DRY. .GLD...NONE. $$ LAMMERS ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 1120 AM CST SUN FEB 23 2003 UPPER LEVEL SYSTEM MOVING ACROSS SOUTHERN OK RESULTING IN MID LEVEL CLOUDS ACROSS NORTHERN PORTIONS OF THE REGION. STEERING WINDS TAKING ON MORE SOUTHERLY COMPONENT...SO CLOUDS SHOULD GRADUALLY EASE AWAY FROM AREA. RUC INDICATING A SECONDARY TROF DEVELOPING OVER EAST TX AND GENERATING LIGHT RAIN. WILL DISREGARD THE RAIN FACTOR...BUT THIS FEATURE COULD EXPLAIN AN AREA OF LOW CLOUDS NEAR COLLEGE STATION. SO THERE GOES CHANGING THE FORECAST THIS AFTERNOON TO SUNNY ACROSS MUCH OF THE REGION...AS IT IS NOW. WILL NEED TO MAKE CHANGES IN WORDING DUE TO THE SHIFTING AND INCREASING WINDS TODAY. WILL ALSO NEED TO ADJUST TEMPS TO ACCOUNT FOR A 15 DEGREE SPREAD FROM NORTH TO SOUTH...ENHANCED BY INCREASED CLOUDS TO THE NORTH. VII .SHV...NONE. $$ la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 335 PM EST SUN FEB 23 2003 12Z RAOBS/LATEST WV LOOP AND RUC ANLSYS SHOW SPLIT FLOW ACRS NAMERICA WITH FA INCRSGLY UNDER DOMINATION OF ARCTIC BRANCH. UPR GRT LKS CURRENTLY UNDER UPR RDGING BTWN POTENT SUBTROPICAL/POLAR BRANCH SHRTWV LIFTING NE THRU THE APPALACHIANS AND SHARPENING ARCTIC BRANCH TROF ACRS SCNTRL CAN. AT THE SFC...STEADY NNE WND BTWN SFC HI PRES OVR SCNTRL CAN AND LO PRES IN THE NE CONUS DRAGGING COLD AIR IN ONTARIO (TEMP/DWPT...GENERALLY -15 TO -25F) S INTO THE NW GRT LKS. NMRS WND PARALLEL LES BANDS HAVE DVLPD DOWNWND OF LARGE HOLE IN THE ICE COVER ACRS SCNTRL LK SUP AND THE SMALLER HOLE OVER THE WRN PART OF THE LK JUST S OF ISLE ROYALE. THIS LES MOST PREVALENT FM ASX-IWD-ONT AND OVR ERN MQT-WRN ALGER ZNS. BUT INTENSITY OF LES LIMITED BY VERY DRY/ STABLE AIR AND SHORTER FETCH THAN NORMAL WITH ICE COVG. 12Z GRB/APX SDNGS SHOW SHARP INVRN HGT H9-925. MQT 88D SHOWS REFLECTIVITY EVEN WITHIN THICKER BAND ON MQT/ALGER BAND GENERALLY AOB 16DBZ WITH JUST A FEW RETURNS APRCHG 20DBZ. THESE BANDS TENDING TO DRIFT E AS LLVL WND FLOW SLOWLY BACKING. TEMPS WELL BLO NORMAL FOR THE SEASON WITH READINGS AT 17Z RANGING FM JUST ABV ZERO AT CMX TO ARND 12 OVR THE SE ZNS. EVEN COLDER AIR NOTED UNDER SCNTRL CAN TROF WITH H5/H7/H85 TEMPS AS LO AS -44C/-32/-30 AT YQD AT 12Z. SFC TEMP/DWPT GENERALLY -30/-40F AT 15Z. DIGGING SHRTWV ACRS THE NRN ROCKIES HELPING TO DRAW THIS COLDER AIR S TOWARD THE NRN PLAINS...AND 12HR H3 HGT FALLS AT GGW AS HI AS 100M. ALTHOUGH DEEP HI RH NOTED ACRS THE NRN PLAINS IN ADVANCE OF THE TROF... ABSOLUTE MSTR IS QUITE LO. PWAT GENERALLY IN THE 0.05 TO 0.15" RANGE...WITH RELATIVE AND ABSOLUTE MSTR A BIT HIER FARTHER S. BKN MID CLD ASSOCIATED WITH THIS MSTR APRCHG WRN CWA ATTM IS A BIT THICKER ACRS SRN MN...WITH SKIES ACRS NRN MN JUST PCLDY. JUST PTCHY -SN RPRTD UNDER THICKER CLD COVER. MAIN FCST CONCERNS THIS PACKAGE INCLUDE SN CHCS ESPECIALLY WITH THE APRCHG ARCTIC BRANCH SHRTWV AND TEMPS. WND CHILLS IN COLD NW FLOW BEHIND ARCTIC BRANCH SHRTWV MON NGT ALSO A CONCERN. FOR TNGT...ETA/GFS/NGM SHOW UPR TROF AXIS MOVG TO NW MN/DAKOTAS BY 12Z MON. MAIN DPVA/H85-5 QVECTOR CNVGC IN ADVANCE OF THIS SHRTWV DOES NOT ARRIVE OVR WRN ZNS UNTIL 12Z. BUT ALL THREE MODELS INSIST ON TRACKING AXIS OF H85-5 QVECTOR CNVGC/WEAK H7 UVM/HIER H7 RH ACRS CWA THIS EVNG WELL IN ADVANCE OF MAIN SHRTWV EVEN THOUGH MAIN DYNAMICS/MOISTENING REMAIN S OF CWA. MODEL QPF JUST A FEW HUNDREDTHS OF AN INCH WITH FALLING TEMPS IN MID LVLS AHD OF THERMAL TROF UPSTREAM NEGATIVELY IMPACTING SN GROWTH POTENTIAL. 12Z MSTR/CLD TRENDS ACRS MN OFFER SOME SUPPORT FOR THE FCST SCENARIO...BUT SAT/ COMPOSITE 88D LOOPS INDICATE THICKER CLD/PCPN ECHOES ACRS SRN MN TENDING TO MOVE MORE E THAN NE...MORE IN LINE WITH GFS FCST H7 UVV. IN FACT...CLD/ECHO UPSTREAM IN NCNTRL MN TENDING TO DSPT EVEN WHERE AT LEAST ETA F6 SHOWS H7 UVV. BUT FCST NLY FLOW OFF LK SUP AND ASSOCIATED SENSIBLE/LATENT HTG MAY HELP TO REJUVENATE MOISTENING/ GENERATION OF SN...ESPECIALLY NR SCNTRL LK SUP (WRN LK MOSTLY ICE COVERED). HAVE OPTED TO MAIN GOING FCST SCENARIO OF HIER POPS DOWNWND OF LK SUP IN NCNTRL DURG PD WHEN MODELS SHOW AXIS OF HIER H7 UVV/RH PASSING BY...BUT CUT POPS ELSEWHERE XCPT THE FAR SCNTRL WHERE GFS SHOWS HIER H7 UVV GIVEN DRYNESS/STABILITY OF ANTECEDENT AIRMASS AND CLD/RADAR TRENDS UPSTREAM. ADJUSTED GOING FCST MINS DOWN A FEW DEGREES IN SOME PLACES TO ACCOUNT FOR VERY LO TEMPS OBSVD THIS AFTN AND CONCERN THAT CLD WL BE THINNER LONGER TNGT THAN PREVIOUSLY FCST IN SLACKENING PRES GRADIENT. GIVEN FCST 12HR H5 HGT FALLS ARPCHG 100M BTWN 06Z AND 18Z MON AS UPR SHRTWV AXIS APRCHS...PREFER GFS FCST OF SHARPER SFC TROFFING OVR CNTRL LK SUP ON MON. ETA DID NOT ADEQUATELY HANDLE WRMG/MOISTENING FM LK SUP PAST 24 HRS...PROBABLY BECAUSE MODEL INITIALIZED WITH MORE ICE COVER THAN ACTUALLY OBSVD. ALTHOUGH ICE PROBABLY BEGINNING TO FILL IN AGAIN WITH ARRIVAL OF MUCH COLDER AIR...THINK SENSIBLE/ LATENT HTG FM LK WL AID IN SFC TROF DVLPMNT PER GFS FCST. BETTER DPVA/ H85-5 QVECTOR CNVGC/H7 UVM MOVES W TO E ACRS CWA MON MRNG. THINK AIR WL BE TOO DRY OVR THE W TO SUPPORT ANYTHING MORE THAN SCT -SHSN...BUT WHEN DYNAMICS INTERACT WITH ENHANCED LLVL CNVGC OVR ECNTRL NR LK SUP...SUSPECT -SHSN WL BCM MORE NMRS-WDSPRD. SN INTENSITY WL BE LIMITED BY LACK OF ISENTROPIC LIFT (MID LVL TEMPS FCST TO CONT TO FALL WITH ARRIVAL OF THERMAL TROF) AS WELL AS POOR SN GROWTH MICROPHYSICS. MODEL QPF JUST A FEW HUNDREDTHS OF AN INCH...SO AN INCH AT MOST SYNOPTIC SN WITH PERHAPS AN INCH IN LK ENHANCMENT ALG TROF AXIS IN ALGER/MQT COUNTIES IN LGT LLVL N FLOW. AS SHRTWV/DYNAMICS PRESS E DURG THE AFTN...CAUSING MID LVLS TO DRY OUT AND LLVL SFC TROF TO PUSH E WITH MORE A NW FLOW DVLPG W TO E... SN CHCS WL DIMINISH W TO E...AND SKIES NR THE WI BORDER WL LIKELY CLR LATER IN DAY AS VERY DRY LLVL AIR PUSHES E OVR LIMITED FETCH ACRS WRN LK SUP. LES INTENSITY OVR THE W WL BE LIMTED BY INFLUX OF DRY STABLE AIR AND EXTENSIVE ICE COVG THERE. WITH FALLING LWR TROP TEMPS...AT LEAST BKN CLD COVER...AND DAYTIME TEMPS BARELY ABV -10F OVR ND...XPCT MAX TEMPS NR VERY LO MOS FCST... GENERALLY IN THE SINGLE NUMBERS ABV ZERO. SHRTWV RDGING/DNVA/H85-5 QVECTOR DVGC WL DOMINATE CWA TMRW NGT AS BRUTALLY COLD AIRMASS DESCENDS ON UPR GRT LKS. SINCE HI PRES CENTER WL DIVE S INTO THE MID MS VALLEY...WNDS WL NOT BE ABLE TO DECOUPLE COMPLETELY AS PRES GRADIENT NEVER BECOMESS FLAT. HOWEVER...EXTREMELY LO TEMPS/DWPTS UPSTREAM WITH JUST A SHORT FETCH FOR XCPTD WNW FLOW ACRS MAINLY ICE COVERED WRN LK SUP WL STILL SUPPORT MINS CLOSER TO LWR NGM/ETA MOS GUIDANCE UNDER MCLR SKIES... ESPECIALLY NR THE WI BORDER WHERE WNDS HAVE A BETTER CHC TO BCM LIGHTER. HAVE OPTED TO RETAIN GOING FCST MINS NR WI BORDER CLOSE TO -25F. WND CHILL ADVY MAY BE NECESSARY OVR AT LEAST THE MORE EXPOSED KEWEENAW PENINSULA WITH ETA SHOWING 20KT WNDS WITHIN MIXED LYR AND WND CHILLS FALLING TOWARD -30F. OTRW...WNDS WL LIKELY FALL BLO 10 MPH ADVY THRESHOLD WHERE AIR TEMPS DROP LO ENUF TO SUPPORT WND CHILLS BLO -25F. WNW FLOW WL CONT LES INTO THE SN BELTS E OF MUNISING... BUT DRY STABLE AIR WL LIMIT COVG/INTENSITY...AND HAVE FCST NO MORE THAN 2 INCHES THERE. LINGERING LES WL END OVR THE E ON TUE AS SFC HI SHIFTS E THRU THE OH VALLEY AND FLOW TURNS MORE WSW. ALTHOUGH CORE OF ARCTIC AIR DEPARTS TO THE E AND THERE SHUD BE PLENTY OF SUN...THINK MAX TEMPS WL NOT BE MUCH HIER THAN TMRW WITH AIRFLOW OUT OF CENTER OF ARCTIC HI/LLVL COLD AIRMASS WITH NO LK SUP MODERATION AT ALL. EVEN MIXING TO H9 ON ETA FCST SDNGS FOR TUE SUG MAX CLOSER TO LWR NGM/ETA MOS GUIDANCE. RELATIVELY QUIET WX WL CONT ON TUE NGT/WED WITH HI PRES RDG HOLDING OVR THE SRN GRT LKS. ETA/GFS ADVERTISE A WEAK SHRTWV IN SLOWLY RETREATING NRN BRANCH SLIPPING ESE THRU ONTARIO DURG THIS TIME...BUT BEST DPVA/H85-5 QVECTOR CNVGC LOOKS TO REMAIN N OF FA. CONSIDERING DRYNESS OF AIRMASS IN PLACE OVR CWA (FCST PWAT ARND 0.1 INCH)...XPCT NOTHING MORE THAN PTCHY CLD ACRS MAINLY THE NRN TIER ZNS. ASSOCIATED INCRS IN PRES GRADIENT WITH PRES FALLS OVR ONTARIO WL LIKELY HOLD WINDS UP TUE NGT AND PREVENT MINS FM FALLING AS LO AS MON NGT. STILL...READINGS NR AT LEAST THE WI BORDER SHUD FALL WELL BLO ZERO. GFS/ETA BOTH SHOW H85 TEMPS 7-8C HIER ON WED AFTN THAN ON TUE. RAISING TUE FCST MAX ABOUT 15F YIELDS READINGS CLOSE TO GOING FCST...20 TO 25. 00Z EXTENDED MODELS AND 06Z GFS NOW ARE NOW TRENDING TOWARD A MORE AMPLIFIED AND ACTIVE NRN BRANCH FLOW LATER THIS WEEK AND NXT WEEKEND. STILL SOME DISAGREEMENT ON SCENARIO FOR THU/FRI WITH ECMWF STILL INSISTING ON AN INTERACTION BTWN NRN/SRN BRANCH FLOW CAUSING SOME CYC FLOW OVR UPR LKS THU/FRI. OTHR FCSTS POINT TOWARD SVRL RELATIVELY WEAK...MSTR STARVED SHRTWVS IN NRN BRANCH FLOW IMPACTING CWA SOMETIME BTWN THU INTO SAT BEFORE ARRIVAL OF COLDER AIR IN THE SAT/SUN TIME FRAME. CONSIDERING MODEL TREND AND SUPPORT FM GFS ENSEMBLES...HAVE REJECTED THE ECMWF SOLN. ALTHOUGH EXPLICIT GFS FCST WOULD SUG A DRY DAY ON FRI AND THEN ON SAT IN ADVANCE OF NXT STRG COLD FNT WITH LES PSBL ON SUN...UKMET/CNDN RUNS SUG THIS STRG COLD FNT WL PASS FRI WITH COLDER WX/LES CHCS COMMENCING ON SAT. GIVEN TIMING UNCERTAINTIES OF DISTURBANCES WITHIN FICKLE NRN BRANCH...WL CARRY A CHC OF SN THU THRU SAT FOLLOWED BY CHC OF LES ON SUN. HAVE ALSO TRENDED PREVIOUS FCST TEMPS FOR FRI/SAT DOWN A FEW DEGREES TO ACCOUNT FOR HIER PROB OF FARTHER S INTRUSION OF COLDER AIR EACH DAY. COORDINATED WITH APX. .MQT...HEAVY FREEZING SPRAY WARNING E HALF OF LAKE SUPERIOR. KC mi