EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 900 PM EST FRI FEB 15 2002 CURRENT...LOCAL METARS NICELY DEPICT THE INVERTED TROUGH AND WEAK LOW ALONG IT...OFFSHORE KSGJ-KX47. DISCERNIBLE WIND SHIFT TO W-NW ALONG THIS FEATURE...WITH DEWPOINTS @8-10F HIGHER OUT AHEAD OF IT. WATER VAPOR/RUC ANLYS SHOW A WEAK UPPER LEVEL VORT/SHEAR AXIS EXTENDING WSW-ENE ACROSS THE CTRL/ERN GOMEX AND FL. SOME MID LEVEL OVERRUNNING IS PRODUCING SOME SPOTTY STRATIFORM -RA OVER/OFFSHORE SW FL. BASED ON LACK OF ECHOES OFFSHORE NORTH OF KSRQ...WILL ASSUME NIL PRECIP BENEATH THE UPPER GUNGE THAT FAR NORTH...EVEN FARTHER WEST IN THE GOMEX. SOME DENSE SEA/FOG STRATUS ALSO NOTED ACROSS NE FL/SE GA ...WEST OF THE WEAK LOW OFFSHORE. FCST...W/R/T THE PRECIP TO THE SW...ANTICIPATE THROWING IN A 20/30 POP FOR SPOTTY LIGHT RAIN FOR THE SRN COUNTIES...AND PERHAPS MENTION SPRINKLES AS FAR NORTH AS KMLB. HIGH CLOUDS RENDERING FOG IMAGERY USELESS...SO WILL NEED TO VIGILANTLY MONITOR SURFACE DATA TO DETECT IF THE FOG SEEPS SOUTHWARD INTO VOLUSIA (AND POSSIBLY LAKE) COUNTY OVERNIGHT. CALLS TO THE KX47 (BUNNELL) AWOS SHOWED THE FOG HAD YET TO MAKE IT THAT FAR SOUTH...SO WILL HOLD OFF ON MENTIONING IT FOR THE TIME BEING. MARINE...WITH INVERTED TROUGH PUSHING BACK OFFSHORE ATTM...WINDS HAVE DROPPED SIGNIFICANTLY AT BOTH 41009/41010. SWELLS ARE INDEED COMING DOWN AS ANTICIPATED...SO WILL GO AHEAD AND STEP DOWN TO A CAUTIONARY STATEMENT FOR SEAS...AND DROP THE CAUTION SOUTH OF COF. .MLB...NONE. PUBLIC/MARINE...CRISTALDI AVIATION/FIRE WX...BRAGAW fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 921 AM EST FRI FEB 15 2002 SOUTH FLORIDA AWOKE THIS MORNING UNDER AN ALMOST COMPLETELY OVERCAST SKY. CULPRIT APPEARS TO BE LOW LEVEL (300-305K) ISENTROPIC LIFT DEPICTED QUITE WELL THIS MORNING BY SHORT-TERM RUC40/WSETA MODELS BUT EVEN LAST NIGHT'S MID RANGE 72 HOUR RUN OF 06Z AVN. ALSO, S FLA WAS UNDER THE INFLUENCE OF THE RIGHT REAR QUADRANT OF A JETLET WHICH MOVED OVER S FLA AFTER MIDNIGHT. A FEW SHOWERS DEVELOPING ACROSS THE SOUTHERN PORTIONS OF THE AREA AFFECTING MAINLY COLLIER, MAINLAND MONROE, MIAMI-DADE BROWARD AND COASTAL PALM BEACH. BY THIS AFTERNOON, MODELS DEPICT THE JET NO LONGER AFFECTING S FLA AND THE ISENTROPIC LIFT BECOMING A DOWNWARD MOTION FEATURE AS WELL BUT TEMPORARILY AS STRONG SHORT WAVE OVER SOUTHERN GREAT PLAINS PLUS REMNANTS OF THE OLD CLOSED LOW THAT WAS ONCE OVER BAJA AND NOW OVER OLD MEXICO SOUTH OF TEXAS MOVE IN TANDEM EASTWARD TOWARD SOUTH FLA TONIGHT INTO SATURDAY AGAIN MOISTENING UP THE ATMOSPHERE WITH JET DYNAMICS AND ISENTROPIC LIFT. BUT THAT'S THIS AFTERNOONS' FORECAST. FOR THE UPDATES, EXPECT THE CLOUDY SKIES OVER S FLA TO ABATE A BIT TO A PARTLY SUNNY AFTERNOON. WORDING IN THE ZONES NEED TO BE ADJUSTED. WITH DIMISHING ISENTROPIC LIFT, EXPECT THE CURRENT ISOLATED TO WIDELY SCATTERED VERY LIGHT SHOWER ACTIVITY TO END OVER LAND BUT POSSIBLY CONTINUE IN THE ATLC. WILL HANDLE THIS WITH NOWCASTS AT THE TIME. THE EXTENSIVE CLOUD COVER MAY AFFECT THE FORECASTED MAXIMUM TEMPERATURES FROM BEING REACHED. THE EAST COAST HAS A BETTER CHANCE SINCE THE FLOW HAS BEGUN OFF THE THE ATLC BUT THE WATER IS IN THE LOWER 70S. THE INTERIOR AND WEST WILL PROBABLY BE COOLER. IN THE MARINE ZONES, 2K RAOB WINDS FROM THIS MORNING INDICATED AN EASTERLY FLOW AND BUOYS ALONG THE E COAST AND IN THE STRAITS SUPPORT THIS. WILL REWORD COASTALS AS NEEDED AS WIND SHIFT HAS OCCURRED. AT THE MOMENT SPEEDS APPEAR FINE. .MIA...NONE. $$ fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 900 EST FRI FEB 15 2002 01Z SFC CHART SHOWS WEAK COLD FRONT SLICING ACROSS OH/KY/TN. TEMPS BEHIND THE FRONT ONLY A FEW DEGREES COOLER THAN AHEAD OF IT...EXCEPT IN IL/IN WHERE THEY ARE UNDER CLR OR NEARLY CLR SKIES. RADAR RETURNS THUS FAR THIS EVENING ARE MAINLY VIRGA. SFC OBS SHOWING THAT TEMPS ARE STAYING UP UNDER CLOUD COVER AND WINDS/MIXING. TEMPS RUNNING UPPER 40S VALLEYS TO LOWER 50S RIDGES AND MORE OPEN AREAS. WILL UPDATE ZONES SHORTLY TO RAISE TEMPS A CATEGORY. NOT REALLY EXPECTING SKIES TO CLEAR (OR PARTIAL CLEARING) UNTIL AROUND/TOWARD SUNRISE. CHC POPS ALSO A TOUGH CALL TNGHT. 18Z MESO-ETA RUN LATCHES ONTO PCPN OVER E AR AND W TN AND RUNS IT ACROSS TN/S KY OVERNIGHT. RUC MODEL SIMILAR. THIS LOOKS A BIT IFFY WITH THE LOW LEVELS BEING SO DRY. SPRINKLES MIGHT BE THE BETTER WAY TO GO...WILL MAKE FINAL DECISION ON THAT HERE SHORTLY. .JKL...NONE. HALL ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1045 PM EST FRI FEB 15 2002 CURRENT SATELLITE LOOPS AND SURFACE OBS INDICATE THAT CLOUDS HAVE BECOME SCATTERED MOST SPOTS BUT MORE CLOUDS UPSTREAM SO HAVE WORDED FORECAST BECOMING MOSTLY CLOUDY MOST AREAS OVERNIGHT. NEW MESO ETA AND RUC SLOWS DOWN APPROACHING SYSTEM WHILE PINPOINTING BEST LIFT/MOISTURE FARTHER SOUTH. HAVE TAKEN OUT POPS OVERNIGHT ACROSS NORTHERN ZONES ACROSS N LOWER AND LOWERED POPS CENTRAL ZONES BUT KEPT LIKELY POPS FAR SOUTH. ZONE UPDATE ALREADY OUT. THANKS TO GRR FOR THEIR COORDINATION .APX...NONE. SULLIVAN mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1100 AM EST FRI FEB 15 2002 THE LATEST SFC ANALYSIS SHOWS LOW PRESSURE OVER THE ERN TIP OF THE UP WITH A COLD FRONT EXTENDING SW INTO NRN IL. TEMPS BEHIND THE COLD FRONT ARE ROUGHLY 10 DEGRESS COLDER THAN AHEAD OF THE FRONT. LATEST VIS LOOP SHOWS CLOUDS DEVELOPING RAPIDLY ACROSS SW LWR IN AREAS WHERE SKIES WERE MOSTLY CLEAR. AS THE FRONT AND UPR SHORT WAVE MOVE THRU THIS AFTERNOON CLOUDS WILL COVER THE FCST AREA; RUC FCST SOUNDINGS SHOW ABUNDANT MOISTURE NEAR 900 MB. REGIONAL RADAR SHOWS SOME LIGHT PCPN ACROSS CENTRAL LAKE MI...CLOSER TO THE LOW. SOME OF THIS PCPN WILL LIKELY MOVE INTO THE NRN CWA THIS AFTERNOON. BUT WITH THE RUC SOUNDINGS SHOWING LOTS OF DRY AIR IN THE MID LVLS I SUSPECT THAT MUCH OF THIS PCPN WILL GO TO VIRGA. THE SAME HOLDS TRUE WITH THE SMALL AREA OF LIGHT PCPN IN THE SRN PART OF THE LAKE. WILL KEEP SPRINKLES/FLURRIES IN THE FCST TO ACCOUNT FOR IT. CAA WILL BUILD IN BEHIND THE FRONT AND KEEP TEMPS STEADY IN THE NORTH. WE'LL PROBABLY SEE TEMPS RISE A COUPLE OF DEGREES IN THE SOUTH. SO NO MAJOR CHANGES TO THE GOING FCST...JUST A TWEAK OR TWO. 93 .GRR...NONE. mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1150 AM EST FRI FEB 15 2002 .DISC...MINOR UPDATE TO ADJUST FOR ONGOING CLOUDS...RAISE A FEW MAXES AND WINDS. PREVIOUS DISCUSSION BELOW... .BOTTOM LINE...NRN STREAM DOMINATES WX NERN US TIL MID/LT NEXT WEEK...RSLTG IN ONLY LOW QPF EVENTS. .PROBLEM OF DAY...RN SHWRS LT TDA WRN ADRNDCKS? RS POPS TO LKLY SAT NGT N/W? .SYNOPSIS...BROAD ULVL RDG INVOF LEFT CST NOAM. VERY BROAD TROAL OVER ERN NOAM/WRN ATLC SHARPENS OVR RIGHT CST BY SUN. ELONGATED HIPRES RDG MID ATLC CST ENE ACRS WRN ATLC. SERIES WK LOPRES/S FM CNDN PLNS EWD TO CNTRL GRTLKS BCMS MORE CONSOLIDATED SAT WHILE SPRAWLING FM SERN QUE PROVINCE TO SRN ONT PROVINCE. AS TROAL SHARPENS SAT...WRN ATLC LOPRES DPNS WHILE MOVG NEWD FM OFF MID ATLC CST. THIS SYS FCST TO BE WELL E CAPE COD BY SAT EVE AND NOT XPC TO AFFECT CWA. .MDLS...AVN/ETA/META/RAFS/2 CNDN MDLS/MM5 SUNYSB EXAMINED FOR THIS FCST. LRG/SCL FEATURES SIMILAR THRU H+48/H+60. AVN IS SOMEWHAT STGR THAN ETA REGARDING LOPRES MOVG NEWD OFF ATLC CST SAT. NCEP PREFERS COMPROMISE BTWN WKR ETA AND STGR AVN. NO WDSPRD QP FCST TIL SAT NGT...AND THAT/S MNLY N/W CWA. ETA QPF SUGGEST CUPL INCHES SNW SAT NGT ADRNDCKS/WRN MHKVLY. RAFS ENHANCES SOME QP SERN HLF CWA LT FRI NGT...WHICH NO OTHER MDL FCSTS. .SHORT TERM...STLT LOOP/SFC OBS SHOW HI CLDNS MOVG EWD ACRS CWA ATTM. RUC40 INDCS WAA W LOW H10/5 RH OVR ALL OF NY. NRST QP IS WELL N OF NY AND IS ASSOC W QSTNRY FNT ENE FM NRN GRTLKS. H10/H5 RH FCST TO INCR TDA...BUT MDLS ARE DRY. AND XCP FOR KUCA WHERE MAV POP 33 PCT...MOS POPS BLO THRESHOLD TDA. PREV ZNS INDC CHC RN SHWRS LT FOR ADRNDCKS...OTRW DRY. WL STAY W THE PREV FCST AS MDLS INDC SOME LGT QP JUST TO NW OF CWA LT...AND MAV POP 33 AT KUCA. SHOULD BE NICE AND MILD AS SLY CRCLN/WAA CONTS. MOS MAXT IN 40S THRUT. .LONG TERM...COOLING OCRS ALF TNGT AS S/W TROAL MOVS INTO CNTRL NY LT. BIG DIFFERENCES BTWN RAFS/BASED FWC AND AVN BASED MAV POPS FOR TNGT. MAV GENLLY MUCH LWR THAN FWC. PREFER MAV AS META/GEM ARE ESSENTIALLY DRY...XCP FOR SOME SPOTTY QP NRN ZNS. PREV FCST HAD LKLY POP N/W CHC ELSW AND MXD PTYPE. THIS LOOKS OKAY...THO POPS MAY BE A BIT HI IN MUCH OF CWA. MAV POP AT KUCA 59 PCT...SO ACPT LKLY POP N/W PER META/GEM QPF FCST. MOS MIN/T MNLY 30/35 OKAY. FOR SAT...MDLS MNLY DRY. MAV POPS GENLLY BLO THRESHOLD/FWC ABV. PREFER MAV. GOING ZN FCST HAS CHC POP THRUT AND WRN/NRN ZNS ARE WORDED MUCH CDR. CDR PERHAPS...MUCH CDR NO...DUE TO BACKING SFC WND AS WK LOPRES APCHS VIA GRTLKS. NEITHER H10/H8 THKNS NOR MOS INDC THAT IT/LL BE MUCH CDR. MM5 FCST SNDGS SAY LTLCG. SO WL MODIFY WORDING. MOS FCST MAXT M30S/M40S SAT...AND WL GO W IT. MDLS HAVE SPOTTY LGT QP SAT...SO WL STICK W PREV ZNS AND KEEP CHC POP IN FCST. .XTND FCST...CNDN GLOBAL/AVN IN PRETTY GOOD AGREEMENT THRU H+120. WK LOPRES RUNS ESE ACRS NRN NY/SRN VT SUN NGT. MOIST NLY LLVL CRCLN ACRS CWA SUN. HIPRES BLDS OVR CWA MON AND OFF ATLC CST TUE RSLTG IN WRMG. AVN/CNDN GLOBAL FCSTG MNLY DRY SUN...TOTALLY DRY MON/TUE. MOS POPS HAVE LOW CHC IN MUCH OF CWA SAT NGT. BASED ON ETA FCST...AM INCLINED TO RAISE TO LKLY IN N/W CWA. BUT SINCE PREV ZNS AGREE WELL W CURRENT MOS FOR SAT NGT...WL STAY W PREV FCST. WL ALSO GO W PREV XTND PORTION OF FCST IN THE 4 AM ZNS. .ALY...NONE. ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1005 AM EST FRI FEB 15 2002 LOOKING AT THE 6 UTC ETA AND THE MOST RECENT RUC...IT APPEARS THAT RETURN FLOW STRATO-CU WL HOLD OFF UNTIL LATE AFTN IN THE SE ZONES. 12 UTC RAOBS SHOW THAT UPSTREAM H5-H3 LEVELS ARE STILL FAIRLY DRY...AT LEAST S OF THE NC/SC BORDER. THUS...WL MOSTLY MOSTLY SUNNY SC ZONES TDA...BUT KEEP PARTLY CLOUDY NC TO ACCOUNT FOR HIGH CLOUDS. WL BUMP UP TEMPS ABOUT 2 DEG AS LOCAL TEMP SCHEME HAS HIGHS AROUND 60 MOST OF THE UPSTATE AND SRN NC PIEDMONT. FCSTID = 14 GSP 60 38 63 36 / 0 20 10 0 AND 61 38 63 36 / 0 20 10 0 CLT 60 39 63 36 / 10 20 20 0 HKY 58 38 59 33 / 0 20 20 10 AVL 55 36 54 30 / 10 30 20 20 .GSP... GA...NONE. NC...NONE. SC...NONE. MCAVOY sc AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 810 PM MST FRI FEB 15 2002 TREND THROUGH 2Z SURFACE ANALYSIS SHOWS PRESSURE GRADIENT SLACKENING ACROSS CWA. MOST OF THE OBS SHOW WINDS LETTING UP SOME. 1Z RUC FORECASTS THIS TREND TO CONTINUE. SO WILL DROP WINDS ABOUT 5 MPH AND ADJUST LOWS DOWN A FEW DEGREES. REST OF FORECAST LOOKS GOOD FOR NOW. .UNR...NONE. RUDGE sd EAST CENTRAL FLORIDA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MELBOURNE FL 1135 PM EST FRI FEB 15 2002 SEA FOG HAS SPREAD THROUGH FLAGLER AND INTO NE VOLUSIA COUNTY OVER THE PAST 2HRS. CALLS TO LAKE/VOLUSIA S.O.'S INDICATE IT IS CONFINED TO NE VOLUSIA WITH LITTLE IF ANY WEST OF I-95 AND NOTHING AT ALL IN LAKE COUNTY. WITH WINDS VEERING TO NW...NO MECHANISM FOR THIS TO SPREAD WWD...BUT IT COULD COME SOUTHWARD OVER THE NEXT COUPLE HRS. ALSO...SINCE IT'S NOT WIDESPREAD ENOUGH TO ISSUE NPW/UPDATE HWO... WILL USE NOW'S TO HANDLE...AND THROW OUT QUICK ONE-ZONE ZFP UPDATE. ------------------------------------------------------------------ PREV DISC... CURRENT...LOCAL METARS NICELY DEPICT THE INVERTED TROUGH AND WEAK LOW ALONG IT...OFFSHORE KSGJ-KX47. DISCERNIBLE WIND SHIFT TO W-NW ALONG THIS FEATURE...WITH DEWPOINTS @8-10F HIGHER OUT AHEAD OF IT. WATER VAPOR/RUC ANLYS SHOW A WEAK UPPER LEVEL VORT/SHEAR AXIS EXTENDING WSW-ENE ACROSS THE CTRL/ERN GOMEX AND FL. SOME MID LEVEL OVERRUNNING IS PRODUCING SOME SPOTTY STRATIFORM -RA OVER/OFFSHORE SW FL. BASED ON LACK OF ECHOES OFFSHORE NORTH OF KSRQ...WILL ASSUME NIL PRECIP BENEATH THE UPPER GUNGE THAT FAR NORTH...EVEN FARTHER WEST IN THE GOMEX. SOME DENSE SEA/FOG STRATUS ALSO NOTED ACROSS NE FL/SE GA ...WEST OF THE WEAK LOW OFFSHORE. FCST...W/R/T THE PRECIP TO THE SW...ANTICIPATE THROWING IN A 20/30 POP FOR SPOTTY LIGHT RAIN FOR THE SRN COUNTIES...AND PERHAPS MENTION SPRINKLES AS FAR NORTH AS KMLB. HIGH CLOUDS RENDERING FOG IMAGERY USELESS...SO WILL NEED TO VIGILANTLY MONITOR SURFACE DATA TO DETECT IF THE FOG SEEPS SOUTHWARD INTO VOLUSIA (AND POSSIBLY LAKE) COUNTY OVERNIGHT. CALLS TO THE KX47 (BUNNELL) AWOS SHOWED THE FOG HAD YET TO MAKE IT THAT FAR SOUTH...SO WILL HOLD OFF ON MENTIONING IT FOR THE TIME BEING. MARINE...WITH INVERTED TROUGH PUSHING BACK OFFSHORE ATTM...WINDS HAVE DROPPED SIGNIFICANTLY AT BOTH 41009/41010. SWELLS ARE INDEED COMING DOWN AS ANTICIPATED...SO WILL GO AHEAD AND STEP DOWN TO A CAUTIONARY STATEMENT FOR SEAS...AND DROP THE CAUTION SOUTH OF COF. .MLB...NONE. PUBLIC/MARINE...CRISTALDI AVIATION/FIRE WX...BRAGAW fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 230 AM CST SAT FEB 16 2002 WATER VAPOR IMAGERY AT 08Z SHOWS SHORTWAVE DROPPING S-SE INTO MN ARROWHEAD ROUNDING BASE OF EASTERN CANADIAN TROUGH. INITIAL FORECAST CHALLENGE IS POTENTIAL FOR -SN OR -RA AS SHORTWAVE PASSES TO NE TODAY. THEN FOCUS TURNS TO RAIN CHANCES MONDAY AND BEYOND. SHORT TERM MODELS APPEARED TOO SLOW AND TOO FAR WEST WITH VORT CENTER LOCATION COMPARED TO SATELLITE TRENDS. AVN ONLY MODEL PLACING QPF INTO EXTREME NE IA AT 06Z AND MORE WIDESPREAD WITH VORT PASSAGE AT 18Z. REGIONAL RADAR AND SURFACE REPORTS INDICATE -SN/-RA MAINLY FROM MSP TO MKE AXIS AT 07Z. ETA LOOKS TO HAVE BEST HANDLE ON SITUATION BY 12Z AND THEN KEEPS MEASUREABLE PRECIP WELL TO NORTHEAST AT 18Z. WILL KEEP LOW SCATTERED POPS IN NW IL ZONES FOR MAINLY MORNING AS STEEP LAPSE RATES WILL BE IN PLACE WITH QG FORCING FROM SHORTWAVE TOWARD 18Z. ELSEWHERE TO W AND SW...MESOETA AND RUC INDICATE DECENT OMEGA WITH SURFACE TROUGH PASSAGE...BUT SUFFICIENT LOW LEVEL MOISTURE LACKING THERE AND WILL CONTINUE ONLY SPRINKLES OR FLURRIES WORDING THROUGH MIDDAY. SUBSIDENCE FROM RIGHT EXIT REGION OF H3 JET DIVING S WILL BEGIN CLEARING TREND IN SE IA ZONES IN AFTERNOON...WHILE LOW LEVEL MOISTURE SHOULD KEEP CLOUDS LINGERING NE OF A SQI-CID LINE INTO EARLY EVENING. TEMPS AND BRISK NW WINDS IN PREVIOUS PACKAGE LOOK ON TRACK...AND WILL STAY ON WARM SIDE OF GUIDANCE. SURFACE RIDGE SLIDES INTO IA BY DAWN SUNDAY. GUIDANCE LOOKS TOO WARM WITH LOWS FOR IA ZONES BASED ON DRY AIRMASS AND IDEAL RADIATIONAL COOLING AND WILL UNDERCUT THERE BUT STAY CLOSE TO MOS IN IL. ON SUNDAY...SURFACE HIGH MOVES ACROSS CWFA AND PREVENTS MUCH MIXING UNTIL WARM AIR ADVECTION KICKS IN TOWARD EVENING. GUIDANCE HIGHS LOOK TOO COOL GIVEN FULL SUNSHINE AND LACK OF SNOW COVER. WILL CONTINUE GOING FORECAST TREND OF ONE CATEGORY ABOVE GUIDANCE FOR HIGHS. 50KT H85 JET PROGGED BY AVN STREAMING INTO IA ZONES BY MONDAY EVENING AS LOW MOVES ACROSS NORTHERN PLAINS. STEEP LAPSE RATES AND WEAK IMPULSES IN SW H5 FLOW SUPPORT GOING FORECAST PACKAGE SCENARIO WITH LIKELY POPS FOR RAIN SHOWERS WEST AND SCATTERED EAST...TRENDING TOWARD LIKELY FOR RAIN ACROSS CWFA BY TUESDAY AND WILL NOT CHANGE MUCH. LATEST AVN AND MRF A BIT FASTER AND WEAKER THAN OTHER MEDIUM RANGE GUIDANCE WITH THIS SHORTWAVE MOVING INTO NORTHERN PLAINS LATE MONDAY AND TUESDAY. DEFINITELY LOOKS LIKE A WET AND UNSETTLED PATTERN FOR MUCH OF WEEK AND WILL LEAVE EXTENDED AS IS. .DVN... IA...NONE. IL...NONE. MO...NONE. DLS il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 AM EST SAT FEB 16 2002 00Z RAOBS/LATEST WV LOOP AND RUC ANAL SHOW TROF OVR THE ECNTRL CONUS DOWNSTREAM OF RDG OVR THE PAC NW/SW CAN. SVRL SHRTWVS APRNT DROPPING SE IN NWLY FLOW BTWN UPR RDG TO THE W AND TROF TO THE E. THE FIRST IS CURRENTLY IN THE CNTRL LKS...WITH A SFC TROF INTO ERN UPR MI. SOME ASSOCIATED LGT SN JUST DEPARTED THE ERN ZNS. ANOTHER FAIRLY POTENT SHRTWV DROPPING SE INTO NRN MN...AND H85 COLD FNT SUPPORTING ENHANCED CLD AHD OF THIS SHRTWV ENTERING WRN ZNS WITH SOME -SN RPRTD ACRS WRN CWA INTO NRN WI. ALTHOUGH PCPN APPEARS LIMITED BY DRY AIR ARND H7 AS DEPICTED ON THE 00Z INL SDNG...SOME LK/UPSLOPE ENHANCEMENT OVR THE W HAS LWRD VSBY TO IFR. WEAK UPR RDGING/H7 DRY ADVCTN BTWN THESE TWO SHRTWVS CURRENTLY BRINGING DRY WX TO THE CNTRL ZNS. OVERALL...SFC/H85 TEMPS OVR THE NW LKS ARE WELL ABV NORMAL... WITH SFC/H85 READINGS GENERALLY 25 TO 35/-5 TO -8C. TEMPS BEHIND H85 COLD FNT DROP TO -12C TO -15C...BUT MAJORITY OF REAL COLD AIR BOTTLED UP OVR HUDSON BAY. ANOTHER SHRTWV APRNT OVR NRN SASKATCHEWAN...WITH UPR AIR STN IN NE ALBERTA RPRTG A 100M 12HR H5 HGT RISE BTWN 12Z-00Z IN THE WAKE OF THIS SYS. MAIN FCST CONCERNS THIS PACKAGE INCLUDE SN/LES CHCS TDAY INTO TNGT...THEN TEMPS LATER TNGT INTO MON AS TROF LIFTS OUT AND PROGRESSIVE UPR RDG/WARMER AIR TRIES TO DISPLACE EXITING COLD AIR. FOR TDAY...BOTH ETA/AVN INDICATE VIGOROUS SHRTWV NR LK WINNIPEG WL DIG SHARPLY INTO THE OH VALLEY BY THIS EVNG...WITH MAJORITY OF PVA/ H85-5 QVECTOR CNVGC/H7 UVV TRACKING JUST TO THE S. SFC OBS OF AXIS OF -SN STRETCHING FM NE MN INTO NW WI SEEM TO SUPPORT THIS FCST. HOWEVER...PATCH OF ENHANCED CLD SWINGING THRU WRN LK SUP SUGS THERE WL BE SOME UPR FORCG TO TRAVERSE EVEN THE NRN PART OF CWA BEFORE DYNAMICS EXIT SOON AFTR 12Z. H85 TEMPS IN ADVANCE OF H85 COLD FNT APPEAR MARGINAL FOR LK ENHANCEMENT...SO SN TOTALS INTO THE MRNG HRS SHUD BE NO MORE THAN A FEW INCHES OVR THE HIER TERRAIN OF THE FAR W WHERE OBSVD WNW FLOW IS MOST FVRBL AND MOST PERSISTENT -SN NOW FALLING. NXT QUESTION TO ANSWER IS EXTENT OF LES THAT DVLPS OVR CWA DURG AFTN IN THE WAKE OF H85 COLD FROPA THIS MRNG FOLLOWING PASSAGE OF SHRTWV TO THE S. AVN MOST AGGRESSIVE AT DRIVING COLD AIR INTO CWA WITH MORE OF A NLY FLOW... ITS FCST H85 TEMP OVR SCNTRL LK SUP BY 00Z SUN DOWN TO -16C (VS -14C FOR ETA/NGM). TREND OF SHRTWVS TO DIG MORE SHARPLY THAN FCST AND FAIRLY HI AMPLITUDE APPEARANCE OF ERN TROF SUGS AVN FCST OF DEEPER PENETRATION OF COLDER AIR THAN ETA/NGM FCST TDAY IS ON TARGET...SO FOLLOWING AVN GUIDANCE TDAY. ARRIVAL OF COLD AIR ALSO IN PHASE WITH APRCH OF SHRTWV NOW IN NRN SASKATCHEWAN. AVN SHOWS AXIS OF H7 UVV/ H7 RH > 70 PCT MOVG N-S OVR CWA THIS AFTN...SO XPCT AT LEAST 3HR PD OF LK ENHANCED SN WITH ENHANCED SFC CYC FLOW. LES CHART SHOWS 1-3 INCHES/6 HRS UNDER XPCTD CIRCUMSTANCES...SO WL GO UP TO 3 INCHES IN MQT-ALGER ZNS WHERE XPCTD 340 FLOW MOST FVRBL AND UPR MOISTENING MOST AGGRESSIVE. ALTHOUGH FAR WRN ZNS APPEAR TO MISS OUT ON UPR MOISTENING...CONCERNED TREND FOR SHRTWV TO DIG MORE SHARPLY THAN FCST MIGHT RESULT IN MORE MOISTENING ALF OVR EVEN THE W. WL GO AN INCH OR TWO FROM IWD-CMX AND AT ERY...WITH UP TO AN INCH OVR INLAND AREAS. SINCE TEMPS SO MILD ATTM...WL GO A COUPLE DEGREES HIER THAN MOS FOR MAX TEMPS. AVN SHOWS H85 THERMAL TROF NR -18C PASSING ACRS SRN LK SUP BY 06Z AS SASKATCHEWAN SHRTWV/H7 UVV DROPS S INTO WI. LES CHART SHOWS 1 TO 3 INCHES/6 HRS FOR DELTA T 17-20C WITH INVRN HGT ARND 5K FT PER CRUDE AVN FCST SDNG. WL FCST ANOTHER 1 TO 3 INCHES IN FVRD ERN MQT-WRN ALGER BEFORE H5 HGT RISES 80M BTWN 06Z AND 12Z AND DRIER AIR SURGES S UNDER NVA IN WAKE OF SHRTWV. HAVE OPTED FOR LES ADVY MQT/ALGER ZNS WITH UP TO 6 INCHES/12 HRS OVR HIER TERRAIN. CONFIDENCE IN ADVY BOOSTED BECAUSE 00Z YPL SDNG RELATIVELY MOIST THRU A RATHER DEEP LYR OF THE TROP. LESSER AMTS IN SURROUNDING LK SUP ZNS AND FARTHER S...NO NEED FOR OTHR ADVYS. AS UPR HGTS RISE AND CYC FLOW WEAKENS LATE...AVN SHOWS RDG AXIS SETTING UP ACRS WRN ZNS...BUT LINGERING TROF ACRS THE E AND CNTRL. WL MAINTAIN MENTION OF CLRG IN THE INTERIOR WRN ZNS AND S CNTRL...WHERE TEMPS SHUD FALL BLO MOS FCST MINS. AOA MOS NR LK SUP FM THE KEWEENAW TO ISQ WHERE LK MODERATION SHUD PREVAIL ALL NGT DESPITE THE DRYING. AS UPR HGTS CONT TO RISE WITH STRG H5 NVA ON SUN...AVN/ETA INDICATE SFC RDG AXIS WL MOVE INTO THE CNTRL LKS BY 00Z MON. AS SFC FLOW SHIFTS BCMS MORE SSW DURG THE DAY...ANY LINGERING LK CLD WL DSPT. DESPITE VERY DRY AIRMASS (FCST PW < 0.25 INCH)...BOTH AVN/ETA BRUSH NRN TIER ZNS WITH PTCHY WAD CLDS. BUT SINCE BEST ISENTROPIC LIFT/ HIEST MSTR ON 290K SFC STAYS TO THE N...XPCT CLD COVG TO BE NO MORE THAN SCT. SO WL CALL THE DAY MOSUNNY AFTR MRNG LK CLDS DSPT. DESPITE DVLPMNT OF SLY FLOW DURG AFTN...FWC/MAV FCST MAX A GOOD CATEGORY UNDER GOING FCST MAX. FCST H85 TEMPS BY 00Z MON ARND -1C OVR THE W TO -8C OVR THE E. IF INCRSG FEB SUN ALLOWS MIXING TO H925...ETA FCST SDNGS SUG MAX TEMPS WL RISE TO 26 AT ERY TO 35 AT IWD (WHERE STRGR GRADIENT WND WL ENHANCE MIXING). SLY FLOW OFF LK MI WL ALSO RETARD WRMG IN THE E. CWA DOMINATED BY INCRSG SWLY FLOW ON SUN NGT INTO MON AS SFC HI PRES RDG PRESSES TO THE E...PRES FALLS ACRS CAN...AND A SHRTWV FM THE PAC PUSHES INTO THE PLAINS. AVN AND UKMET MOST PROGRESSIVE WITH THE PAC SHRTWV...AND AVN BRKS OUT PCPN OVR THE WRN HALF OF CWA LATE ON MON. ETAX AND CAN ARE SLOWER AND DRIER. WITH THE AMPLIFYING TROF OVR THE E AND DRY ANTECEDENT AIRMASS...PREFER THE SLOWER DRIER ETAX/CAN. HOWEVER...GOING FCST HAS MENTION OF PCPN ALL ZNS LATE ON MON...SO WL CUT BACK TO KEEP ERN HALF DRY. INCRSG SW WND ON SUN NGT WL LIMIT DIURNAL TEMP FALL ESPECIALLY OVR THE W DESPITE MCLR SKIES...SO AOA MOS FOR MINS HERE. BUT ENUF RADIATIONAL COOLING OVR THE E BEFORE THE SHARPER GRADIENT SNEAKS IN TO ALLOW TEMPS TO FALL CLOSER TO MOS FCST. DRY AIR AND AVN FCST H100-85 THKNS NO HIER THAN ABOUT 1300M SUG ANY PCPN ON MON WL BE SN DESPITE MAX TEMPS AOA FRZG. COORDINATED WITH APX/GRB. .MQT...LES ADVY THIS AFTN/TNGT MIZ005-006. KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 325 EST SAT FEB 16 2002 ...SNOW INTO MIDDAY THEN SCT SNOW SHOWERS INTO THE OVERNIGHT... THE MAIN QUESTION EARLY THIS MORNING IS JUST HOW MUCH SNOW WILL FALL TODAY AND WERE WILL THE HEAVIEST SNOW BE? THE NEXT QUESTION IS HOW MUCH LAKE EFFECT SNOW SHOWERS WILL THERE BE OVERNIGHT? THE 00Z ETA WAS TO SLOW IN BRINGING THE LOW AND MID LEVEL MOISTURE IN WHILE THE RUC AND AVN DID A BETTER JOB SINCE THE RADAR MOSAIC SHOWS A LARGE AND GROWING AREA OF PRECIPITATION FROM WI INTO SOUTHWEST LOWER MICHIGAN AT 07Z. THE PRECIPITATION IS MOSTLY SNOW EXCEPT NEAR THE LAKE MICHIGAN SHORE AT 07Z. THE ETA HAS MOST OF THE PRECIPITATION ON THE SHORTWAVE WHICH AT 06Z WAS JUST COMING INTO NW MN. ALL OF THE MODELS ARE VERY SIMILAR ON THE TRACK OF THE SHORTWAVE AND DEVELOPMENT THE SFC LOW THAT MOVES ACROSS NRN LK HURON THIS AFTERNOON AND TO THE NYC/BOS COASTAL AREA BY SUNDAY MORNING. THE BEST WAA EARLY THIS MORNING IS OVER THE SOUTHERN 1/3 OF LOWER MICHIGAN AND THE BEST DYNAMICS ASSOCIATED WITH THE SHORTWAVE ARE ALSO OVER THE SRN 1/2 OF LOWER MICHIGAN THIS MORNING INTO EARLY THIS AFTERNOON. THE COLD FRONT ASSOCIATED WITH THE SFC LOW MOVES ACROSS THE CWA DURING THE LATE MORNING INTO EARLY THIS AFTERNOON. AFTER THAT ALL OF MICHIGAN IS IN THE DEEP COLD AIR AS THE POLAR JET IS WELL SOUTH AND WEST OF LOWER MICHIGAN BY THEN. THERE WILL BE ENOUGH COOLING FROM ALL OF THIS DYNAMICS TO CHANGE THE RAIN NEAR THE LAKE SHORE TO SNOW BY SUNRISE. THE 1000/850 THICKNESS FALL FROM 1305 NEAR THE MKG/BIV AREA AT 06Z TO NEAR 1300 BY 1200Z. GIVEN THE LOW PRECIPITATION WATER (BETWEEN .3 AND .4 INCHES) AND THE 700 MB MIXING RATIO NOT MORE THAN 2 K/KG... SO SINCE THAT MOISTURE DOES NOT LAST 12 HOURS... REALLY ONLY 8 HOURS... WILL GO WITH 1 TO 3 INCHES OVER THE SRN 2/3 OF THE CWA WITH AROUND AN INCH NORTH SINCE MOST OF THE MOISTURE WILL BE SOUTH. ONCE THAT SYSTEM MOVES OUT THE INVERSION HEIGHTS CRASHES TO 5000 FT. WITH 850 TEMPS FALLING INTO THE -12 TO -14C RANGE TONIGHT... IT WILL BE COLD ENOUGH FOR LAKE EFFECT SNOW SHOWERS AND THE -15C WILL BE IN THE CLOUD LAYERS. ALSO... THERE IS A TRAILING SHORTWAVE ON THE BACK EDGE OF THE DEEP COLD AIR THAT CROSSES LOWER MICHIGAN AROUND 06Z. THUS WITH THE MEAN WIND BELOW THE INVERSION FROM AROUND 330 AT AROUND 30 KNOTS OVERNIGHT... THE BEST LAKE EFFECT SNOW SHOWERS WILL BE CLOSE TO THE LAKE SHORE. I WILL GO WITH SNOW SHOWERS LIKELY NEAR THE LAKE SHORE TONIGHT AND SCATTERED SNOW SHOWERS INLAND DUE TO THE SHORTWAVE. THE SNOW SHOWERS INLAND WILL QUIET AFTER MIDNIGHT AS THE SHORTWAVE CLEARS THE AREA. COULD EVEN BE PARTIAL CLEARING INLAND AS IS TYPICAL WITH NORTH WINDS AND DEEP COLD AIR OVER LOWER MICHIGAN. ON SUNDAY... THE SFC HIGH PRESSURE RIDGE MOVES ACROSS LOWER MICHIGAN. THE GOOD WARM ADVECTION DOES NOT START UNTIL SUNDAY EVENING. FLURRIES WILL BE POSSIBLE SUNDAY MORNING NEAR THE LAKE SHORE AS THE NORTH WINDS DO NOT TURN WEST UNTIL EARLY AFTERNOON. SO I WILL FCST PARTLY CLOUDY INLAND AND FLURRIES ENDING... BECOMING PARTLY CLOUDY NEAR THE LAKE SHORE. SUNDAY NIGHT... THE GOOD WARM ADVECTION MID AND HIGH CLOUDS SHOULD BE WELL NORTH OF LOWER MICHIGAN... NEAR THAT SYSTEM IN CENTRAL CANADA. ALSO WITH THE SYSTEM MOVING INTO THE PLAINS. SO I WILL GO MOSTLY CLEAR. TEMPERATURES WILL HAVE A HARD TIME FALLING AFTER MIDNIGHT AND A LOW LEVEL JET NEAR 30 KNOTS DEVELOPS AND THAT SHOULD RESULT IN ENOUGH MECHANICAL MIXING TO KEEP THE TEMPERATURE FROM FALLING TO FAR. ZONES BY 430 AM. WDM EXTENDED FORECAST THE SFC WEATHER MAP BY MONDAY WILL FEATURE A HIGH PRESSURE RIDGE IN THE EAST AND DEVELOPING LOW PRESSURE OVER THE PLAINS STATES. THIS PUTS OUR REGION IN STRONG SOUTHERLY FLOW THAT WILL ALLOW TEMPS TO MODERATE INTO THE 40S MONDAY AFTERNOON. THE GULF OF MEXICO WILL REALLY OPEN UP AND GULF MOISTURE WILL ADVECT NORTH... SO WE WILL HAVE INCREASING CLOUD COVER AND BREEZY CONDITIONS. OCCASIONAL RAIN SHOWERS WILL DEVELOP EARLY TUESDAY MORNING AND CONTINUE THROUGH THE DAY AS THAT PLAINS SYSTEM DRAWS CLOSER. ON WEDNESDAY COLDER AIR WILL BEGIN TO FILTER IN AS THAT SYSTEM SHIFTS EAST. WE WILL KEEP A CHANCE OF RAIN OR SNOW SHOWERS GOING IN THE FORECAST. HOWEVER... MODEL TRENDS ARE BRINGING COLDER AIR IN A BIT SOONER... IMPLYING ANY LIGHT PRECIPITATION WEDNESDAY MAY FALL PREDOMINANTLY IN THE FORM OF SNOW. BY THURSDAY THE 500 MB TROUGH WILL DIG INTO OUR REGION. IT CERTAINLY DOESN/T LOOK LIKE A BIG SURGE OF COLD AIR BUT IT WILL BE COLD ENOUGH FOR SNOW. IMPULSES OF H5 ENERGY SWINGING THROUGH THE TROUGH WILL CAUSE OCCASIONAL SNOW SHOWERS TO DEVELOP THROUGH THE DAY. THE H5 TROUGH WILL ALREADY BE SHIFTING EAST FRIDAY AS UPPER LEVEL FLOW TRANSITIONS INTO A MORE ZONAL PATTERN TOWARDS NEXT WEEKEND. MEDIUM RANGE GUIDANCE CONTINUES TO BE FAIRLY CONSISTENT AND NO CHANGES WERE REQUIRED TO OUR GOING EXTENDED FORECAST. LAURENS .GRR...NONE. mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 206 AM EST SAT FEB 16 2002 ...UPDATED ZONES TO BRING THE PRECIPITATION IN FASTER... LATEST RADAR AND SFC OBS SHOW THE PRECIPITATION HAS ALREADY STARTED AT MKG...BIV AND GRR. THIS CONFIRMS THE AVN AND RUC HAVE A BETTER HANDLE ON THE INCREASE IN THE LOW AND MID LEVEL RH IN RESPONSE TO THE LOW AND MID LEVEL WARM ADVECTION/ISENTROPIC LIFT. THE ETA PUTS MOST OF THE PRECIPITATION ON THE SHORTWAVE DEFORMATION ZONE (PASSING OVER SW LWR BETWEEN 12Z AND 18Z). THE RUC AND AVN PUT IT MOSTLY WITH THE ISENTROPIC LIFT NEAR 700 MB (285K)... WHICH PUTS IT MOSTLY BETWEEN 09Z AND 15Z. I BELIEVE IT WILL BE BOTH. SINCE SFC TEMPS ARE NEAR 39F ALONG THE LAKE SHORE AND THE PRECIPITATION IS RAIN THERE... THE ETA HAS THE 1000/850 1305M LINE AT 06Z FROM LDM TO 10 EAST OF BIV TO NIL. CURIOUSLY THAT IS WERE THE RAIN/SNOW LINE IS. THICKNESS COOLING FROM DYNAMICS WILL CHANGE THE RAIN TO SNOW ACROSS THE ENTIRE CWA BY 12Z. THE ETA HAS THE 1305 LINE NEAR I-94 AT 12Z. SO THE UPDATE HAS RAIN TO SNOW NEAR THE LAKE SHORE AND MOSTLY SNOW INLAND... AND MOSTLY OVER SOUTHWEST SECTIONS OF LOWER MICHIGAN BEFORE SUNRISE. EXPECT MOST OF THE SNOW TODAY WILL BE FROM GRR AND SOUTH. MORE ON THAT IN THE AFD FOR THE MORNING ZONE PACKAGE COMING OUT BY 330 AM. WDM .GRR...NONE. mi FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 325 AM CST SAT FEB 16 2002 FORECAST CHALLENGE CONCERNS MAINLY EARLY CLOUD TRENDS AND TEMPERATURES. MODELS IN GOOD AGREEMENT WITH MAIN FEATURES THROUGH PERIOD. PREFER AVN THERMAL AND DRIER ETA/RUC MOISTURE FIELDS IN EARLY GOING SO WILL LIKELY USE MIX. SHORTWAVE IN NW FLOW ALOFT PUSHING THROUGH FORECAST AREA AT THIS TIME. THIS FEATURE...UPPER JET CORE AND SE ORIENTED BAROCLINIC ZONE RESPONSIBLE FOR BAND OF CIGS OF VARYING HEIGHT FROM RRV EAST. KMVX 88D INDICATING ANY RETURNS HAVE SHIFTED SOUTH AND EAST OF FA AND WITH METARS -SN FREE WILL NOT INCLUDE ANY AM FLURRY. FOR REMAINDER OF DAY UPPER RIDGE TO BEGIN TO SHIFT EAST HOWEVER REGION WILL REMAIN IN NW FLOW ALOFT WITH SFC HIGH SHIFTING OVER FORECAST AREA. UPPER JET CORE ALSO SHIFTS EAST AND SHOULD TAKE CLOUDS WITH IT. FROM SATELLITE IMAGERY WILL MAINTAIN CLOUD MENTION THIS AM WITH MOST AREAS SEEING QUITE A BIT OF SOLAR BRUNT OF DAY AS DRIER AIR SHIFTS EAST. FAR NORTHEAST TO BE IN CLOUDS LONGEST. IN SPITE OF WEAK COLD AIR ADVECTION WILL CONTINUE TREND OF TEMPS ABOVE GUIDANCE CONSIDERING SOLAR AND LACK OF ANY SNOW COVER WITH COOLEST READINGS OVER NE COUNTIES WHICH MAY FEEL AFFECTS OF COLD FRONT CLIPPING AREA. UPPER RIDGE FLATTENS AND MOVES INTO FORECAST AREA OVERNIGHT INTO SUNDAY. 850MB TEMPS RECOVER NICELY AND CONSIDERING GRADIENT SHOULD BE SUFFICIENT MIXING. THIS COMBINED WITH DRY AIRMASS FOR GOOD SOLAR AND WITH LACK OF SNOW TEMPS AGAIN SHOULD TOP GUIDANCE PUTTING READINGS CLOSE OR ABOVE RECORD READINGS. NEXT WAVE TO AFFECT REGION OR PARTS OF ON MONDAY. AVN PRETTY BULLISH ON QPF HOWEVER CONSIDERING PAST EVENTS WILL NOT BITE AT THIS TIME HOWEVER BEARS WATCHING AND MAY NEED TO EXPAND PCPN CHANCES FARTHER ACROSS REGION. WILL LEAVE CURRENT WORDING AS IS FOR NOW AND GIVE DAY CREW HEADS UP. NO CHANGES PLANNED TO EXTENDED WITH SPRING LIKE CONDITIONS TO CONTINUE WITH NEXT WARM-UP TOWARDS WEEKS END. .FGF...NONE. VOELKER nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 330 AM CST SAT FEB 16 2002 FORECAST FOCUS ON EXTENT AND DURATION OF LIGHT SNOW TODAY. IN THE SHORT TERM...COMBO OF IR SATELLITE AND RUC 500 MILLIBAR PROG SHOWS CENTER OF 26 UNIT VORTICITY CENTER APPROACHING CENTRAL MINNESOTA. ETA/AVN/RUC/NGM PROGS ALL CAPTURE THIS VORTICITY CENTER AND PLACE IT OVER NORTHERN ILLINOIS BY 18Z. TIME CROSS SECTIONS SHUT OFF ASSOCIATED UPWARD VERTICAL MOTION WITH THIS SYSTEM BY 18Z. THEN DOWNWARD MOTION AND DECENT NEGATIVE VORTICITY ADVECTION SHOULD BREAK UP CLOUDS DURING AFTERNOON...EVEN WITH MINOR SECONDARY TRAILING VORTICITY IN UPPER FLOW. TIME CROSS SECTIONS DO TRY TO HOLD ONTO LOW LEVEL MOISTURE PAST 00Z SO WILL ONLY MENTION PARTLY SUNNY FOR AFTERNOON AND THEN GO WITH CLERING SKIES OVERNIGHT. FEEL PATH OF VORTICITY CENTER AND MEAGER MOISTURE OF AIRMASS FAVORS ONLY NORTHEAST PORTION OF CWA TO HAVE ANY POSSIBILITY OF PICKING UP AROUND AN INCH OF SNOW BEFORE IT ENDS. IN THE FAR TERM...ALL PROGS BUILD HIGH PRESSURE INTO REGION TONIGHT AND IT DOMINATES WEATHER FOR SUNDAY. WILL GO WITH MORE OPTIMISTIC SKY COVER FOR SUNDAY AND LEAN TOWARD WARMER FWC GUIDANCE NUMBERS FOR FORECAST HIGHS. .MKX...NONE. 0...0...0.../...0...0 $$ ZAJDEL wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1120 AM EST SAT FEB 16 2002 MAIN CONCERN THIS FCST PACKAGE IS THE AMNT OF SHSN THIS AFTN AND TNGT. WV IMAGERY SHOWING A SHRTWV MOV OVR CWA THIS AM. KMQT-88D SHOWING THIS SHRTWV DEPOSITING -SHSN ACRS THE CWA. A LTL STRONGER ACTIVITY IS OVR WI. KINL AM RAOBS SHOWING A DRY LYR NR SFC...AND MOIST ARND 775MB. SFC ANLYS DEPICTING A LOW CENTER OVR CNTRL LWR MI AND A LARGE RDG STRETCHING ACRS N PLAINS...MAN...INTO HUDSON BAY. A CDFNT REMAINS N OF LK SUPERIOR OVR ONT. RUC/MESOETA ANLYS SHOWING THE WEAK SHRTWV PASSING OVR THE CWA THIS MRNG WILL BE FOLLOWED QUICKLY BY ANOTHER THIS EVE. RUC/MESO-ETA/AVN ALL POINT TO KEEPING THE CDFNT OVR LK SUPERIOR THIS AFTN BEFORE SLIDING IT OFF TO THE E WITH THE APPROACH OF THE RDG. LAKE-850MB DELTA-T'S WILL INCR TO 16C ACRS N LK SUPERIOR. LOW LVL WNDS CONVRGNC WILL BE MARGINAL...BUT ENOUGH TO CONT LES ACRS CWA. ETA FCST SOUNDING DATA INDC BASE OF INVRSN ARND 900MB (2K FT). CAA WILL BRING THE INVRSN UP TO 500MB (3.1K FT). CYC FLOW AHEAD OF N PLAINS RDG WILL KEEP WNDS OUT OF THE N THIS AFTN. 850-700MB Q-VEC SHOWING MAINLY DVRGNC ACRS CWA THIS AFTN AND 280K ISENTROPIC ANLYS DEPICT SUBSIDENCE. ONLY SOURCE OF LIFT COMES FM LOW LVL (925MB) WND CNVRGENCE. HOWEVER...IT IS WEAK. AVN A LTL STRONGER WITH THIS LES EVENT...DEPICTING DELTA-T'S ARND 17C AND SOME BLYR WND DIVERGENCE BY 00Z SUN. MESO-ETA/RUC SUPPORTS ONLY 1 TO 2 INCHES THIS AFTN...WHEREAS...AVN SUG 2 TO 4 INCHES. A COMPROMISE OF 1 TO 3 INCHES STILL LOOK REASON FOR LES PRONE AREAS OF E U.P. THUS WILL KEEP THE ADVISORY GOING. AVN INCR DELTA-T'S BY MIDNGT TO AROUND 19C ...HOWEVER...SHOW A LOSS OF LOW LVL CONVRNGNC. AVN SOUNDING FCST SHOWING NR SATURATION BLO 850MB THU 06Z. SFC RDG WILL MOV INTO W LK SUPERIOR BY SR...DRYING OUT THE LOW LVLS. MESO-ETA DEPICTING A LTL WRMR AT 850MB. WEAK 925MB WND CNVRGNC CONT OVR E LK SUPERIOR TIL 06Z. LTL STRONG SHRTWV ENERGY WILL MOV ACRS CWA OVRNGT. ISENTROPIC ANLYS SHOWING MAINLY SUBSIDENCE. Q-VEC HAS ONLY WEAK CONVGNC BY 12Z. ALL IN ALL IT APPEARS THAT LES WILL CONT TIL MIDNGT...BUT TAPER OFF CONSIDERABLY BY SR. 1 TO 3 INCHES POSSIBLE THIS EVE OVR E CWA. LES WILL TAPER TO FLURIES WHEN THE SFC RDG MOV ACRS CWA SUN MRNG AS WNDS WILL BCM LGT AND VARIABLE. WILL KEEP LES GOING FOR THIS EVE. LES WILL END AS WNDS VEERING S. AVN/ETA SHOWING WAA ABV 850MB...WILL ALSO BRING SOME SUNSHINE TO THE U.P. ON SUN. TEMPS SHOULD REBOUND NICELY TO ARND 30 ON SUN. .MQT...LES ADVY THIS AFTN/TNGT MIZ005-006. DLG mi SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1104 AM EST SAT FEB 16 2002 THE SURFACE COLD FRONT CURRENTLY EXTENDS FROM CENTRAL LAKE HURON TO SOUTHERN LAKE MICHIGAN...CROSSING CENTRAL LOWER MICHIGAN. THE WATER VAPOR LOOP SHOWS A POTENT SHORT WAVE TROUGH OVER THE WISCONSIN/ILLINOIS BORDER. LIFT AHEAD OF THIS SHORT WAVE AND ASSOCIATED COLD FRONT HAS LED TO AREAS OF SNOWFALL ACROSS SOUTHERN LOWER MICHIGAN. LOW LEVEL FRONTOGENETICAL FORCING AND MID LEVEL DEFORMATION HAS ALLOWED THE SNOWFALL TO BE ORIENTED IN A BANDED STRUCTURE ACROSS THE FORECAST AREA THIS MORNING...WITH THE HEAVIEST SNOWFALL BETWEEN FLINT AND THE TRI CITIES...WITH MOST OF METRO DETROIT SEEING A BREAK IN THE PRECIPITATION DURING THE LATE MORNING HOURS. PRECIP COVERAGE ON KGRR RADAR HOWEVER HAS ALREADY INCREASED AS THE SHORT WAVE TO THE WEST HEADS SOUTHEAST. THIS WILL BRING ANOTHER ROUND OF SNOWFALL EARLY THIS AFTERNOON. THE 12Z MESO ETA AND LATEST RUC HAVE PICKED UP ON THE FASTER PROGRESSION OF THE SURFACE AND UPPER LEVEL FEATURES. COLD FRONT IS PROGGED TO SWING THROUGH THE AREA THE AFTERNOON...REACHING DETROIT BY 21Z...WITH THE SHORT WAVE PROGGED TO SWING INTO CENTRAL INDIANA BY THIS TIME. FORCING SHOULD THUS DIMINISH FROM NORTH TO SOUTH DURING THE AFTERNOON. THE 12Z MESO ETA IS PICKING UP ON THE PRECIP IN SW LOWER...AND BRINGS IT ACROSS THE 1-96 AND 1-69 CORRIDORS EARLY THIS AFTERNOON. WILL LIKELY SEE ANOTHER INCH IN THESE AREAS BEFORE SNOWFALL TAPERS OFF MID AFTERNOON. WITH FRONT MOVING THROUGH...TEMPS SHOULD NOT STRAY FAR FROM CURRENT READINGS. .DTX...NONE. CONSIDINE mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN FRANCISCO CA 900 AM PST SAT FEB 16 2002 CLOSED UPPER LOW OUT NEAR 38N/130W IS MOVING DUE EAST. IR SATELLITE IMAGERY INDICATES ASSOCIATED FRONTAL BAND IS CURRENTLY CROSSING 125W HAS BEEN SHOWING SOME ENHANCEMENT OVER THE PAST COUPLE OF HOURS AS A JET MAX SWINGS AROUND THE BASE OF THE LOW AND UPPER DIFFLUENCE INCREASES. TIMING THE ONSET OF PRECIPITATION IS THE PRIMARY SHORT TERM FORECAST CONCERN. THIS SYSTEM IS DEFINITELY MOVING FASTER THAN WHAT WAS ANTICIPATED 24 HOURS AGO. RADAR IS DETECTING RAINFALL ABOUT 100 MILES WEST OF POINT ARENA. THE RAIN BAND IS MOVING EAST AT ABOUT 20 MPH WHICH WOULD BRING RAIN TO THE SONOMA COUNTY COAST EARLY THIS AFTERNOON. THIS IS CONSISTENT WITH THE 12Z RUN OF THE ETA AND 06Z RUN OF THE PACRUC MODEL WHICH BOTH SHOW RAINFALL DEVELOPING IN SONOMA COUNTY BY 21Z AND THEN EAST TO THE DELTA AND SOUTH TO MONTEREY BAY BY 00Z. WILL UPDATE ZONES TO INCREASE POPS TO CATEGORICAL IN NORTH AND WEST ZONES THIS AFTERNOON. RAIN WILL SPREAD OVER THE REMAINDER OF THE CWA THIS EVENING. ISOLATED THUNDERSTORMS ARE POSSIBLE TONIGHT AS THE UPPER LOW TRACKS INLAND AND THE AIRMASS DESTABILIZES. AIDING THUNDERSTORM DEVELOPMENT WILL BE A GOOD SHEAR PROFILE FROM THE SURFACE TO 10K FEET. THERE SHOULD BE ENOUGH COLD AIR WITH THIS SYSTEM TO BRING SNOW LEVELS DOWN TO 3500- 4000 FEET...LOW ENOUGH FOR A DUSTING OF SNOW ON THE HIGHEST PEAKS. AN UPSTREAM SHORTWAVE TROUGH SEEN ON SATELLITE NEAR 50N/150W WILL BE WHAT KEEPS OUR CLOSED LOW MOVING EAST. IT WILL DROP INTO THE PACIFIC NW AND FAR NRN CA ON SUNDAY AND SCATTERED SHOWERS SHOULD CONTINUE THROUGH SUNDAY EVENING. A SHORTWAVE RIDGE WILL BRING DRY WEATHER BACK TO OUR REGION BRIEFLY SUNDAY NIGHT AND MOST OF MONDAY. RAIN CHANCES WILL RETURN BY MONDAY EVENING WHEN THE NEXT SYSTEM TAKES AIM AT THE PAC NW AND NORTHERN CA. STS/SFO 896 LVK/SJC 796 MRY 686. DYKEMA .SFO...TDA...SCA...POINT ARENA TO POINT SUR. ca SOUTHWEST IDAHO/SOUTHEAST OREGON AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BOISE IDAHO 145 PM MST SAT FEB 16 2002 TRACE OF SNOW LAST NIGHT AT BURNS AS UPPER LOW OPENED UP AND MOVED MAINLY SOUTH TO N AND FASTER THAN 12Z RUNS - WAS OVER MOUTH OF COLUMBIA AT 12Z INSTEAD OF CLOSER TO 18Z - NOW WELL NW OF BOISE CWFA. LATEST RUC IS EVEN FASTER THAN AVN AND BRINGS IN H5 LOW TO NEAR SFO AT 6Z WITH AVN STILL A BIT OFFSHORE. SO WILL GO WITH AVN'S FASTER AND MORE SOUTHERN TRACK. THAT UPPER LOW OFF SFO THIS AFTERNOON HAS STRONGER WESTERLY KICKER WITH SPEED MAX AROUND 38N FROM 165W TOWARD 145W, FAVORING FASTER AVN SOLUTION (LOW NEAR ELKO MIDDAY SUNDAY) OVER SLOWER ETA FOR SYSTEM (LOW CLOSER TO SHASTA MIDDAY SUNDAY). WE HAVE A PROGRESSIVE RIDGE OVER ROCKIES WHICH SHOULD ALLOW UPPER LOW TO MOVE IN (BUT STILL WEAKEN) AND THE STRONGER KICKER SHOULDN'T BE DISCOUNTED EVEN THOUGH IT TURNS FROM A WRLY SPEED MAX INTO A NWRLY MAX DIVING DOWN THE BACK SIDE OF THIS NEXT UPPER LOW. SO WILL GO WITH AVN WHICH MEANS INCREASING CLOUDS TONIGHT. ON SUNDAY HARNEY/MALHEUR AND SW IDAHO MOUNTAINS-HIGHLANDS WILL GO LIKELY RAIN WITH 1-3" SNOW ABOVE 5K'...HIGH CHANCE POPS FROM ONO-BOI AND MID CHC POPS BKE TOWARDS TWF. PLAN A 20 POP FOR MYL SUNDAY WITH SRN TRACK OF NEXT UPPER LOW...BUT WITH RIDGE OVER ROCKIES MAY SEE MORE ENERGY OVER SW IDAHO SUNDAY AFTERNOON. UPPER LOW OPENS UP OVER SE IDAHO SUNDAY NIGHT BUT FOR SUNDAY EVENING PLAN TO GO LIKELY FOR SRN ID MTNS AND CAMAS PRAIRE AS WELL AS EAST OF BOISE IN UPR T.V. PLAN CHANCE POPS ACROSS THE REST OF THE NW PART OF THE CWA. THIS IS DUE TO A SHORTWAVE MORE IN THE NRN BRANCH CROSSING INTO EASTER OREGON TOWARDS EARLY MONDAY THEN ACROSS MYL-BOI AROUND NOONTIME...WITH SCT VALLEY RAIN AND MTN SNOW SHOWERS. AVN IS A BIT DEEPER WITH THIS FEATURE OVER BOTH THE 00Z MRF AND 12Z ETA AS THE AVN IS CARRYING (AT 18Z MONDAY) THE H5 546DM COUNTOUR S OF BOISE WHILE THE ETA HAS IT WAY UP IN THE IDAHO PANHANDLE. CHANCE POPS EVERYWHERE EAST OF BNO (20 POP) MONDAY WITH THIS FEATURE. SHORT WAVE RIDGING BUILDS IN MONDAY NIGHT BUT MOIST WARM ADVECTION WITH THETA-E RIDGE PUSHES INTO THE CASCADES BY TUESDAY MORNING PROBABLY WITH VIRGA/SPRINKLES-FLURRIES INTO SE OREGON BY MORNING. THE TUESDAY SYSTEM LOOKS TO BE A "GOOD" PRECIP MAKER WITH LIKELY POPS AND RISING SNOW LEVELS BUT STILL SOME SNOW ACCUMULATION EXPECTED TUESDAY. HIGHEST POPS NEXT SEVEN DAYS WITH THIS FEATURE. WILL GO WITH LIKELY POPS OVER SE OREGON ALL TUESDAY AND OVER SW IDAHO FOR 'AFTERNOON' PER AVN/MRF MODEL SOLUTIONS, QPF, AND MEXMOS EVEN THO IT'S DAY 3. ASSOCIATED CD FNT COMES NOW RIGHT ON THE HEELS OF THE WARMFRONT CROSSING SE OREGON TUESDAY NIGHT AND THROUGH MAGIC VALLEY PROBABLY EARLY WEDNESDAY MORNING. EXPECT SCATTERED MAINLY MOUNTAINS SNOW SHOWERS WEDNESDAY BEHIND CDFNT. RIDGE BUILDS IN THURSDAY BUT MOIST WAA IS ADVERTISED IN 12Z AVN MAINLY TOWARDS CASCADES SO WILL LEAVE POPS OUT STILL FOR THURSDAY AND TREND TOWARDS LESS CLOUD COVER ESPECIALLY SW IDAHO VALLEYS AND OWYHEES-HIGHLANDS. WILL STICK WITH CURRENT EXTENDED A BIT COOLER WITH CHANCE POPS FOR FRIDAY AND SATURDAY AS UPPER JET AXIS AND COLD FRONTAL PASSAGE OCCUR SOME TIME BETWEEN THURSDAY NIGHT AND FRIDAY AND COLD TROFFINESS LINGERS OVER THE CWFA SATURDAY THOUGH SOME DRY RIDGING WORKS INTO HARNEY CO TOWARDS NEXT SATURDAY. .BOI...NONE. MILLS id