WESTERN COLORADO & EASTERN UTAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 925 PM MST TUE FEB 16 1999 LATEST RUC AND ETA APPARENTLY MUCH LESS IMPRESSIVE WITH INCOMING SYSTEM...AT LEAST FOR TONIGHT. BOTH ETA AND RUC SHOW DEEP MOISTURE NOT ARRIVING UNTIL 12Z WED...THEN ONLY OVER NORTHEAST UTAH AND EXTREME NORTHWEST COLORADO. WAA ALSO INDICATED TO CONTINUE OVERNIGHT AND LAPSE RATES TO REMAIN FAIRLY STABLE AS A RESULT. THESE TWO FACTORS COMBINED WITH SUBSIDENCE ALOFT AND SHORTWAVE RIDGING NOT POINTING TO ANY SIGNIFICANT CHANCE OF PRECIPITATION OVER THE FORECAST AREA TONIGHT. CONSEQUENTLY...WILL BACK OFF LIKELY WORDING IN COLORADO MOUNTAINS AND WILL REMOVE PRECIPITATION CHANCES FOR CENTRAL COLORADO VALLEYS. SOUTH LACKS MOISTURE SO WILL REMOVE PRECIPITATION CHANCE FOR WESTERN SAN JUANS. WILL LET MIDNIGHT CREW SORT OUT SNOW AND BLOWING SNOW ADVISORY AS STILL WAITING FOR THE REMAINING MODEL SUITE TO ARRIVE. NL NNNN co STATE FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 1043 AM CST WED FEB 17 1999 PESKY LIGHT SNOW HERE AND THERE TO BE MAIN CHALLENGE THIS UPDATE ALONG WITH TEMPS AND CLOUDS. NICE VORT MAX THAT INITIALIZED OVER CEN NEB AT 12Z HAS NOW PROGRESSED ESE TO SE NEB AT 1630Z. BEST LIFT WITH THIS WEAK SYSTEM OVER EXTREME SW IA AND POINTS SOUTHWEST ALONG WITH DEEPER MOISTURE WITH THIS SYSTEM AS DEPICTED BY 12Z RUC. A LITTLE SNOW FALLING FROM IT HAS REDUCED VISBYS TO MVFR CAT IN SW IA. DEEPER CLOUDS SLIDING SE AS DISPLAYED ON VISIBLE SAT LOOP AND 12Z RUC. RUC MOVES BEST LIFT SE OUT OF IA BY EARLY AFTERNOON INTO MO. FARTHER NORTH...A FEW LOWER CIGS/VSBYS INDICATE A FEW FLURRIES HAVE BEEN FALLING IN NRN IA. ADDITIONALLY...A FEW MAY MAKE IT INTO SE CORNER OF CWA...BUT CERTAINLY NOT MEASURABLE. STILL PLENTY OF CLOUDS OVER STATE AND IN ERN NE/SE SD. A MINOR BREAK OVER WRN IA ATTM...BUT IT SHOULD BE PRETTY INCONSEQUENTIAL FOR THE MOST PART AND NOT EFFECT TEMPS TOO MUCH. ON THAT NOTE...FCST HIGHS MAY BE A BIT WARM CONSIDERING AMOUNT OF CLOUDS AND LIGHT WINDS OVER STATE UNDER THE RIDGE. THUS WILL NUDGE THEM DOWN A BIT. UPDATE TO BE OUT BY 1715Z. .DSM...NONE SEARCY NNNN ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 952 AM EST WED FEB 17 1999 WILL BE UPDATING FORECAST SOON FOR WORDING AND OTHER CHANGES. FORECAST PROBLEM FOR THIS AFTN IS WAVE ALG FNT MOVING UP FROM THE TN VLY INTO SRN/CNTL APPLS AND IF ANY RAIN WILL PUSH INTO SEKY. 13Z SFC ANALYSIS SHOWED ON WAVE ON FNT OVER SE TN MOVING INTO SW VA AT 1445Z VIA RADAR AND SAT. CD FNT STRETCHED SW INTO SRN LA WITH ANOTHER WAVE DOWN THERE. RADAR COMPOSITE LOOPS FROM GULF COAST STATES AND TN SHOW MORE RAIN HEADING NE ALG FNT AND 12Z RUC SHOWS SOME MOISTURE CONVERGENCE SCRAPING FAR SE KY THIS AFTN. GIVEN THAT THE LOW LVL FLOW/BELOW 900 MB WILL STAY IN FAVORABLE UPSLOPE INTO AFTN WILL PUT CHANCE LIGHT RAIN FOR FAR EAST ZONES FOR THE AFTN. LOW CLDS WILL BREAK UP SOMEWHAT IN THE FAR NW/SW ZONES THIS AFTN AS SFC HI POKES IN BUT WILL WORD AS BECOMING MOSTLY CLOUDY THERE...LATE. FOR THE CWA IN BETWEEN WILL KEEP CLOUDY...WITH SPOTTY DRIZZLE AND FOG. WILL WORD TEMPS AS STEADY IN THE EAST WITH HIGHS IN THE WEST AS CLOUDS THIN SOMEWHAT BY LATE AFTN. SHOULD HAVE AN UPDATE OUT TOWARD 1530Z. THE FOLLOWING IS PRELIMINARY GUIDANCE FOR COORDINATION ONLY. OFFICIAL FORECASTS ARE FOUND WITHIN PRODUCT SDFZFPKY JKL 48/30/46 220 LOZ 48/28/48 200 WHP/09 NNNN ky SYNOPTIC EXPLANATION/FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON 945 AM EST WED FEB 17 1999 FRONT STILL MOVING SLOWLY EAST THRU W VA THIS MORNING. PREFNTL SHOWRS ARE ALSO MOVING SLOWLY E THRU THE BALTO AND WASH METRO AREAS. RUC AND ETAX SHOW THE MAIN VVS DURING THE MORNING THEN DISSOLVING SOMEWHAT DURING THE AFTERNOON BEFORE PICKING BACK UP TNT. A LOW ALREADY EVIDENT IN THE DEEP SOUTH WITH MOVE NE INTO WSTRN NC BEFORE MOVING INTO THE MID ATL TNT WITH OCCSNL RAIN A SAFE BET. TMPS WILL BE HIT OR MISS TDY WITH BRKS IN THE CLDS DURING THE ERLY AND MID AFTN. PLAYED THE MIDDLE OF THE ROAD WITH TEMPS BTWN AREAS THAT SEE MORE RAIN VS AREAS THAT SEE MORE SUN. .WBC...NONE. STRONG NNNN md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 405 PM EST WED FEB 17 1999 LATEST SFC CHART SHOWS FAIRLY SHARP SFC TROF OVR SCNTRL LK SUP IN GENERAL CAD/CYC FLOW OVR GRT LKS BEHIND DEPARTING UPR VORTEX TO E. MQT 88D VWP INDICATES NRLY UNIDIRECTIONAL WINDS BACKING SLOWLY MORE NWLY DURG DAY AS SFC TROF HAS LIFTED SLOWLY NWD...AND SN BANDS ON RADAR SCREEN HAVE SHIFTED MORE INTO ALGER COUNTY DURG DAY AS REFLECTIVITIES HAVE FALLEN (NOW MAINLY 20DBZ RETURNS WITH ISOLD >28DBZ). 12Z RAOBS AND ETA BUFKIT FCST SDNGS SUG INVRN HGT IN 3K-5K RANGE WITH H85-LK DELTA-TS ARND 16-18C. EVEN THOUGH LK EFFECT SN CHART SUGS 1-2"/ 6 HR ACCUMS FOR THESE CONDITIONS...NMRS RPRTS FM KEWEENAW INDICATE SN CAME DOWN AT A 1"/HR RATE MUCH OF DAY AND EVEN WITH MORE UNFVRBL TRAJECTORY. WENT WITH WRNG EARLY AFTN THERE. APRNTLY LO LVL CNVGC ASSOCIATED WITH SFC TROF HAS BEEN ENUF TO PRODUCE TOTALS MORE IN LINE WITH LK ENHANCED. HOWEVER...LATEST VIS PIX INDICATE CONSIDERABLE DRYING OVR WRN LK IN NWLY FLOW ON S SIDE OF SFC TROF. LATEST RPRTS FM KEWEENAW/ONT/IWD SHOW SN INTENSITIES DIMINISHING AS BACK EDGE OF CLD OVR WRN LK HAS SHIFTED TO THE SE. LATEST RUC AND 12Z MODELS IN GENERAL AGREEMENT THAT SFC-H85 CYC FLOW WL DIMINISH DURG OVRNGT AS UPR LO CONTS TO NE. THUS XPCT ANY LK ENHANCEMENT TO END DURG EVNG. HOWEVER...GENERAL NLY FLOW WITH H85 THERMAL TROF UPSTREAM PROGGED TO LINGER. SO WL GO WITH ACCUMS OVRNGT MORE IN LINE WITH LK EFFECT SN CHART IN AREAS WITH FVRBL TRAJECTORY FOR FCST NNW WIND AND DROP ALL HEADLINES. CONSIDERABLE LO LVL DRYING OBSVD OVR WRN LK SUP AND WEAKENING LO LVL FLOW WL RESTRICT LES OVR IWD-ONTONAGON AREAS. WL GO A FEW DEGREES ABV MOS TNGT FOR MIN TEMPS GIVEN FLOW OFF LK SUP BUT ABV FWC POPS IN LES AREAS. AS UPR LO SHIFTS EWD TMRW...UPR FLOW INTO FRI WL BCM MORE CONFLUENT WNWLY...AND MODELS SHOW A GRDL INCRS IN PRES WITH MORE ACYC NNELY FLOW. ALTHOUGH H85 TEMPS WL REMAIN LO ENUF TO KEEP DELTA-T IN 13-16C RANGE...LWRG INVRN HGTS AND DRYING DEPICTED ON RH-TIME SECTIONS WL NEGATIVELY IMPACT LES. MOST PERSISTENT -SHSN WL LINGER IN AREAS FVRD IN NNELY FLOW. MOS MAX TEMPS LOOK OKAY...BUT MINS FOR THU NGT APPEAR A BIT LO AGAIN FOR AREAS NR LK SUP. KC NNNN mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1045 AM EST WED FEB 17 1999 SAT LOOPS SHOW COMMA CLD ASSOCIATED WITH UPR CYC CIRCULATION APRNT NR ERN CWA GRDLY MOVG NEWD WITH COLDER CLD TOPS SHIFTING AWAY FM CWA AS WELL. SHARP JET MAX MOVG ENEWD ON SE FLANK OF UPR LO AS DEPICTED ON WV LOOP HELPING TO CARRY SYS INTO CAN. ASSOCIATED SFC LO OVR LK HURON WITH FAIRLY SHARP SFC TROF HANGING BACK ACRS CWA. NMRS BRKS IN CLD NOTED SRN CWA AND MN/WI ACCOMPANYING LO LVL DRY AIRMASS. ALTHOUGH WV LOOP SHOWS ANOTHER JET MAX DROPPING SEWD ON BACK SIDE OF UPR LO...THIS JET HAS A MORE SHEARED OUT APPEARANCE. 00Z NGM APPEARS TO HAVE BEST HANDLE ON THIS SECOND JET MAX. RECENT RADAR LOOPS/SFC RPRTS INDICATE A GENERAL DCRS IN REFLECTIVITIES LAST COUPLE OF HRS... BUT CMX INDICATED A PD OF MDT-HVY SN AND 88D STILL SHOWING SOME REFLECTIVITY > 28DBZ OVR ERN MQT/WRN ALGER COUNTIES. VSBL PIX INDICATE BAND FM JUST N OF P59 INTO ERN MQT COUNTY WITH UPSTREAM CONDITIONING OFF LK NIPIGON. TREND HAS BEEN FOR ACTIVITY TO SHIFT EWD WITH TIME...COINCIDENT WITH BACKING OF WIND TO A MORE 340 DEGREE ORIENTATION AS OBSVD ON 88D VWP AND FCST ETA 6KM H95 WINDS SHIFTING BEST LO LVL CNVGC EWD. WINDS IN SFC-8K LYR NRLY UNIDIRECTIONAL AT 15-20 KTS. 12Z H85 TEMPS SUG DELTA-T IN 16-17C RANGE. 12Z LOCAL SDNGS SHOW INVRN HGTS IN 3K-5K RANGE. MAIN QUESTION FOR TDAY IS EXTENT OF SN AND HOW TO HANDLE ANY HEADLINES...INCLUDING GOING WRNG FOR MQT COUNTY. LATEST RUC MODEL CONFIRMS EARLIER MODELS FCST THAT MAIN UPR LO AND ITS ASSOCIATED MSTR/UVV WL CONT SHIFTG NEWD TDAY. THUS LK ENHANCED EVENT WL CONT TO SHIFT TO A PURE LES. FOR OBSVD CONDITIONS...LES CHART SHOWS 1-3"... BUT LO LVL FLOW TO REMAIN QUITE CYC TDAY WITH SECOND JET MAX DIGGING BEHIND UPR LO TO MAINTAIN SFC TROFFINESS. NRLY UNIDIRECTIONAL WINDS SFC-4K PROGGED TO BACK ONLY SLOWLY. ETA 6KM H95 WINDS INDICATE PERSISTENCE OF SGNFT LO LVL CNVGC IN FAR ERN MQT COUNTY AND MAINLY WRN ALGER COUNTY THRU DAY. SINCE REFLECTIVITES >28 DBZ STILL OBSVD IN THE ERN MORE POPULATED PARTS OF MQT COUNTY...WL CONT WRNG THERE FOR TIME BEING. WL GO ABV LK EFFECT CHART NUMBERS AND ADVY FOR ALGER COUNTY...MAINLY WRN PART...GIVEN PERSISTENCE OF LO LVL CYC FLOW/HIER OBSVD REFLECTIVITY/ SGFT FCST LO LVL CNVGC AND UNIDIRECTIONAL FLOW/PRECONDITIONING OFF LK NIPIGON IN UPWIND TRAJECTORY. ALTHOUGH A FEW DECENT SN RPRTS HAVE COME IN FM KEWEENAW...WL NOT POST ADVY THERE GIVEN LESS FVRBL LO LVL FLOW DIRECTION. KC NNNN mi STATE FORECAST DISCUSSION...UPDATED FOR SOUTHEAST MI NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1025 AM EST WED FEB 17 1999 BANDS OF LIGHT SNOW (FLURRIES) AND DRIZZLE OVER THE CENTRAL PART OF CWA ARE SHOWING SIGNS OF DIMINISHING THIS MORNING. EARLY MORNING SURFACE ANALYSIS INDICATED THAT BANDS WERE ASSOCIATED WITH GOOD SURFACE CONVERGENCE OVER THAT AREA. LATEST RUC SHOWS WINDS TO BECOME MORE UNIFORM DURING THE LATE MORNING INTO THE AFTERNOON. THEREFORE...EXPECT A DOWNWARD TREND OF PRECIP. STILL CAN'T TOTALLY RULE OUT CHANCE FOR FLURRIES DURING THE AFTERNOON WITH ENOUGH LOW LEVEL MOISTURE AND CAA. VISIBLE PICTURES SHOWING A FEW BREAKS IN THE OVERCAST...SO WILL LIKELY REWORD MOSTLY CLOUDY ALL AREAS. BT#6 NNNN mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1158 AM CST WED FEB 17 1999 LATEST VIS SATELLITE IMAGERY SHOWS CONVECTIVE CLOUD TOPS OVER NERN AND ERN KS/XTRM WCNTRL MO...ASSOCIATED WITH VORT CENTER THAT 15Z RUC HAD ANALYZED NEAR SLN. LATEST IR SATELLITE SHOWS COOLING CLOUD TOPS IN VCNTY OF TOP...WHERE 1SM -SN WAS REPORTED AT 16Z AND FROM MKC TO 75 MILES SW OF MKC. MKC REPORTED 1/2SM SN AT 17Z. NORTH/SOUTH CROSS SECTION FROM LATEST ETA INDICATES CSI FROM ABOUT 750 TO 500MB. THIS IN COMBINATION WITH DYNAMIC LIFT FROM PVA WAS PRODUCING CONVECTIVE PCPN. 700MB TEMPS AROUND MINUS 10 AND 850MB TEMPS AROUND ZERO WAS ALLOWING MUCH OF THE PCPN TO FALL AS SNOW. BASED THIS UPDATE ON 09Z RUC AS 15Z RUC LOST CONTINUITY WITH VORT CNTR. 09Z RUC MOVES VORT MAX ALONG THE NORTHERN MOST COUNTIES OF CWA AND BELIEVE THAT MOST PCPN WILL BE CONFINED ALONG AND NORTH OF VORT TRACK. BASED ON THE ABOVE...I INCLUDED A 20 PERCENT POP FOR -SN FOR THE NRN COUNTIES OF CWA. PCPN TYPE COULD BE BOTH RAIN AND SNOW DUE FOR THOSE COUNTIES FURTHEST TO THE EAST...DUE TO DAYTIME HEATING OF SFC TEMPS. IF PCPN IS BRIEFLY HEAVY...PCPN TYPE WILL MOST LIKELY BE SNOW. I DO NOT XPCT ANY SIG ACCUM. D.STEINMETZ NNNN mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 845 AM MST WED FEB 17 1999 FOG AND LOW CLOUDS PERSIST IN FALLON COUNTY BUT SHOULD DISSIPATE IN THE NEXT COUPLE HOURS AS SATELLITE FOG LOOP SHOWS BACK EDGE OF FOG MOVING RAPIDLY EAST. PACIFIC SYSTEM SPLITTING AS MAIN ENERGY MOVES INTO WYOMING WITH TRAILING COLD FRONT JUST INTO WESTERN MONTANA. WINDS HAVE NOT DEVELOPED AS YET AND WILL ADJUST IN ZONES ACCORDINGLY. PRECIPITATION INTO WESTERN PORTIONS OF CWA PER PREVIOUS FORECAST AND WILL LEAVE ALONE. NO NEW DATA AS YET BUT GOING ON TFX SOUNDING AND RUC DATA WILL ADJUST TEMPS DOWNWARD A FEW DEGREES MAINLY WEST ZONES. CHANGES WILL BE MADE THIS PACKAGE. THORICHT BIL JB 039/026 040/023 040 58421 LVM .. 041/023 040/... ... 58421 HDN .. 040/022 040/... ... 58421 MLS .. 042/023 040/018 ... 58431 4BQ .. 042/023 040/... ... 58431 BHK .. 040/021 038/... ... 58431 SHR JB 042/020 038/015 040 58441 NNNN mt STATE FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 230 PM EST WED FEB 17 1999 SHORT TERM...VERY COMPLEX SITUATION. THERE IS A FAIRLY WELL DEFINED FRONTAL BOUNDARY ACROSS THE REGION THIS AFTERNOON. LOW PRESSURE APPEARS TO BE FORMING ALONG THIS FRONT IN THE VICINITY OF NY HARBOR. ALL THREE SYNOPTIC MODELS PICK UP ON THIS WHILE THE 15Z RUC DOES NOT. THUS...BASED ON OBS AND SYNOPTIC MODELS EXPECT THE WEAK LOW TO TRACK NE TOWARDS BOSTON BY MORNING. THIS CAUSES THE COLD AIR AND STRATUS TO SLIDE BACK ACROSS ALL OF THE CWA. PCPN IS VERY LIGHT ATTM. WILL CALL IT MAINLY DRIZZLE WITH LIGHT RAIN MORE LIKELY AS WAVE DEVELOPS ALONG THE CAROLINAS BY 12Z. AVN IS FASTER WITH THIS LOW MOVING UP THE COAST. WITH THE MODELS VERY DIVERGENT BY FRIDAY EVENING. QPF DIFFERS ALSO BETWEEN MODELS. WILL NOT INCLUDE HEAVY AT TIMES AS EXPECTING 1/4 TO 1/2 INCHES. HEAVIEST IN EASTERN SECTIONS. LONGER TERM...NEXT SYSTEM COMES OUT OF THE ROCKIES ON LATE THURSDAY WITH THE SYSTEMATIC LIKE ERROR SEEN IN THE NGM PLACING THE LOW CENTER TOO FAR NORTH IN MISSOURI. ETA/AVN SOLUTION OF LOW WEST OF MEMPHIS MORE LIKELY. THIS LEAVES RIDGING OVER THE REGION FOR FRIDAY. ETA AND AVN WAVES ALONG THE FRONT OVER THE ATLANTIC FAR ENOUGH AWAY TO ALLOW FOR PARTLY SUNNY CONDITIONS. LONG TERM...LOW MOVES TO NORTH CAROLINA COAST BY 12Z SAT. THIS IS VERY CLOSE TO THE 00Z MRF RUN POSITION. THUS...THINKING THAT THE AVN/MRF HAS A FAIRLY GOOD HANDLE ON SYSTEM FINALLY. LATEST ENSEMBLE DATA FOR SATURDAY ALSO LOOK VERY CONSISTENT. 12Z RUN OF THE NAVY NOGAPS GSM IS ALSO SHOWING A COASTAL DEVELOPMENT...JUST FASTER THAN MRF. OLD ECMWF IS SOUTH OF THE MRF TRACK...BUT STILL HAS COAST DEVELOPMENT. WITH NEGATIVE TILT UPPER TROF...EXPECT TURN UP THE COAST AND DEVELOPMENT OF THE LOW. AS FOR COLD AIR...QUICK LOOK AT THE MRF 850 TO 1000 MB THICKNESS LOOKS LIKE WE'LL BE RIGHT ON THE CRITICAL THICKNESS WITH THE 850 MB TEMPS COLD ENOUGH (-6 C) TO SUPPORT MAINLY SNOW. STRONG AGEOSTROPHIC FLOW WILL PULL IN THE COLD AIR NEEDED TO SUPPORT SNOW. MRF QPF IS AROUND 3/4 OF AN INCH. CONCERN WOULD BE FOR THE WHOLE SYSTEM SLIDING OUT TO THE SOUTH. WITH MINIMAL PCPN. BASED ON ALL I'VE SEEN...THINK THAT THIS WILL BE THE MOST SNOW NYC AND LI HAS SEEN SINCE APR 96. WILL NOT ISSUE ANYTHING SPECIAL WITH THIS PACKAGE...EXCEPT TO UP TO LIKELY THE CHANCE OF PCPN FOR SAT. MARINE...TIDES ARE AS HIGH AS 1 TO 1 1/2 FT ABOVE. DON'T EXPECT ANY SIG PROBLEMS AS NE FLOW FOR FRIDAY IS EXPECTED TO BE WEAKER THAN PREVIOUSLY FCST. WILL KEEP THE SCA MAY BE NEEDED FOR LATE THURSDAY FOR NOW. COORDINATED WITH TAUNTON AND PHILLY. THANKS. .NYC...NONE. TONGUE NNNN ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1010 AM EST WED FEB 17 1999 SATELLITE IMAGERY SHOWING LOW CLOUDS EXTENDING ALL THE WAY BACK TO THE MISSISSIPPI. MORNING ILN SOUNDING SHOWING SHALLOW LAYER OF MOISTURE TO ABOUT 900 MB. 03Z MESOETA PROGGED SOUNDINGS SHOW MOISTURE STAYING TRAPPED BELOW INVERSION THROUGHOUT THE DAY...AS A RESULT WILL GO WITH CLOUDY WORDING ACROSS FA. 12Z RUC SHOWS THE BEST DRYING PUSHING INTO CVG BY 00Z..SO WILL GO MOSTLY CLOUDY THERE. AS A RESULT OF MORE EXTENSIVE CLOUD COVER THAN PREVIOUSLY THOUGHT WILL LOWER TEMPS TO JUST A FEW DEGREES HIGHER THAN CURRENT CONDITIONS. THIS ALSO LINES UP WELL WITH LAMP OUTPUT. WATER VAPOR SHOWING A SHORT WAVE OVER MID MS VLY SLOWLY MOVING TOWARDS FA. THIS WAVE APPEARS TO BE NOT HANDLED WELL BY THE MODELS. THE 12Z RUC AND 03Z MESOETA TRIES TO PUMP OUT SOME PRECIP OVER NRN IN/SRN MI AND 00Z ETA PRECIP FIELDS BECOMES MORE SQUIRLY BY 00Z THIS AFT. LAF REPORTED FLURRIES EARLIER THIS AM SO WILL THROUGH IN FLURRY WORDING IN WEST CENTRAL OHIO. .ILN...NONE. TIPTON NNNN oh EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 820 PM PST WED FEB 17 1999 A STRONG PACIFIC JET STREAM WILL CONTINUE TO DIRECT STORMS INLAND WELL TO THE NORTH OF SOUTHERN CALIFORNIA THROUGH SATURDAY WITH HIGH CLOUDS CONTINUING TO STREAM ACROSS SOUTHERN CALIFORNIA. A COASTAL EDDY WILL BRING MORE EXTENSIVE NIGHT AND MORNING COASTAL LOW CLOUDS AND FOG THROUGH FRIDAY. A GULF OF ALASKA STORM MAY MOVE FAR ENOUGH SOUTH TO BRING A CHANCE OF RAIN TO SOUTHERN CALIFORNIA LATE SUNDAY AND EARLY MONDAY. A NUMBER OF MINOR UPDATES TO THE CURRENT PACKAGE THIS EVENING. DURING THE NEXT TWO DAYS...A STRONG PACIFIC JET STREAM WILL CONTINUE TO DIRECT STORMS INLAND WELL TO THE N OF SRN CA WITH ASSOCD HIGH CLOUDS STREAMING ACROSS SRN CA. AT LWR LVLS A DEVELOPING CSTL EDDY WL RESULT IN MORE EXTENSIVE NIGHT AND MORNING LOW CLOUDS AND FOG IN CSTL SXNS. THE 00Z RUC LOW LVL WIND FIELD FORECASTS AND 12Z AND 18Z ETA MEAN SEA LVL PRESSURE FIELD FORECASTS ALL SHOW A CSTL EDDY DEVELOPING OVERNIGHT. CURRENT FOG PRODUCT IMAGERY IN RAMSDIS IS SUGGESTIVE OF THIS AS WELL. 00Z RAOBS AND ACARS SOUNDINGS SHOW A MARINE INVERSION NR 1500 FT. WITH HEIGHTS ALF QUITE HIGH AND CHANGING LTL OVERNIGHT... EXPECT ONLY MINOR GRADAUAL DEEPENING OF THE MARINE LYR OVERNIGHT TO AROUND 2000 FT THU MORNING. THIS SHOULD BE SUFFICIENTLY DEEP FOR STRATUS TO PUSH INTO THE VLYS OF SAN COUNTY AND THE INLAND EMPIRE BY MORNING. WITH HEIGHTS ALF BEGINNING TO LWR A LTL THU NIGHT AND WITH ETA MSLP FORECASTS ONCE AGAIN SUPPORTIVE OF EDDY DEVELOPMENT...EXPECT ADDITIONAL DEEPENING OF THE MARINE LYR THU NIGHT/FRI MORNING TO AT LEAST 2500 FT OR POSSIBLY A LTL DEEPER. IF THIS DEEPENING TREND DEVELOPS...LATER SHIFTS MAY NEED TO LWR CSTL/VLY HIGH TEMPERATURES A LTL FOR FRI. SAN BB 0000 .SAN...NONE. MARTIN NNNN ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 940 PM EST WED FEB 17 1999 LATEST SFC OBSERVATIONS AND 88D SHOW THAT MUCH OF THE AREA HAS STOPPED SNOWING. THE EXCEPTION ARE MULTI BANDS SETUP IN THE NNW FLOW OVER THE KEWEENAW...EASTERN MARQUETTE AND ALGER COUNTIES. THE MOST PERSISTENT OF THESE HAVE BEEN OVER ALGER COUNTY. 88D RETURNS HAVE SHOWN A WEAKENING TREND THE PAST FEW HOURS. 00Z RUC BOUNDARY LAYER WINDS FCST HAS WIND TURNING BACK TO THE NNE OVERNIGHT. THIS COULD RESULT IN SCATTERED SNOW SHOWERS REFORMING IN MORE OF A NORTH-SOUTH ORIENTATION. WILL THUS STILL MENTION SCT -SHSN OVER ALL COUNTIES BORDERING LAKE SUPERIOR. CURRENT SFC OBS SHOW TEMPS AT A PACE TO BE A LITTLE BLO CURRENT MIN FCST...WILL LOWER MOST AREAS ABOUT 5 DEGREES. WINDS HAVE ALSO LET UP...WILL MAKE A FEW ADJUSTMENTS. NO OTHER CHANGES PLANNED. LULOFS NNNN mi STATE FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 915 PM EST WED FEB 17 1999 DISC: NEXT S/W IN SERIES MOVING NE THRU SRN APPALACHIANS AND SPREADING -RA INTO SRN ZONES. TEMPS ABOVE FREEZING AND NOT GOING ANYHWERE OVERNIGHT. RAIN WILL CONTINUE RIGHT THROUGH THE NIGHT INTO LATE MORNING/EARLY AFTERN SRN ZONES WITH THE RUC DIRECTING AN AREA OF ABT .50-.75 INCH AT THE SHORE. DEW POINTS ARE RUNNING HIGH AND WE'LL SEE SOME FOG IN RAIN FREE CALM AREAS...DOWN TO ABT 1/2 MILE IN SPOTS. NEXT LOW OVER MO BY THU NIGHT WILL HAVE A TOUGH TIME TAKING UP RESIDENCE OVER ANY PARTICULAR SPOT TOO LONG WITH FAST PROGRESSIVE FLOW CONTINUING FROM THE CENTRAL PACIFIC. ENJOY... .PHI...NONE. SCA MAY BE NEEDED HEADLINED. SEE YA EBERWINE NNNN pa STATE FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 1030 AM EST THU FEB 18 1999 VERY BUSY MORNING ACROSS SOUTH FLORIDA WITH STRONG TO SEVERE SHOWERS AND TSTMS. AXIS OF MAIN WX NOW EXTENDS FROM JUST OFFSHORE PALM BEACH COUNTY AROUND THE S TIP OF THE PENINSULA TO S OF THE KEYS. WX S OF THE KEYS WILL CONTINUE INTO THE AFTN WHILE MOST OF THE THREAT OVER THE MAINLAND HAS PASSED. TECHNICAL PROBLEMS WITH UPPER AIR HAVE BEEN SOLVED AND WE SHOULD HAVE A LATE SOUNDING SHORTLY. HAVENT LOOKED AT MUCH DATA BUT DOESNT LOOK LIKE MUCH ACTIVITY OVER LAND TODAY. HOWEVER...WE ARE STILL AHEAD OF THE FRONT AND THE RUC STILL SHOWS US TO BE UNSTABLE THROUGH THE AFTERNOON...SO A SHOWER OR TSTM IS NOT COMPLETELY OUT OF THE QUESTION...JUST MINIMAL SUPPORT UNLESS WE GET A SEABREEZE LATER TODAY. UPDATED FORECAST FORTHCOMING. AS FAR AS THE COASTALS...CHANGES HAVE BEEN MADE TO HEADLINES AND WORDING. .MIA...SCA FLAGLER BEACH TO COCOA BEACH. CARROLL NNNN fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 900 AM EST THU FEB 18 1999 CURRENT FORECAST LOOKS GOOD... WILL UPDATE TO CLEAN-UP THE WORDING. AFTER LOOKING AT THE RUC AND MM5 EXPECT THE COLD FRONT OVER THE PANHANDLE TO MOVE INTO THE FL BIEND AREA EARLY THIS AFTERNOON AND WASH OUT AS DRIER AIR MOVES IN. NEXT SHORT WAVE WILL SWING THROUGH FRIDAY EVE BUT HAS LITTLE MOISTURE. JOHNSON NNNN fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 955 AM EST THU FEB 18 1999 14Z SFC ANALYSIS SHOWS A WEAK NE FLOW OVER ERN KY WITH HI PRS RIDGING IN FM THE GTLKS INTO WRN KY. VIS SAT CONTINUES TO SHOW LOW CLDS HANGING TOUGH IN ERN KY WITH BREAKS SHOWING UP IN A FEW SPOTS. 850 ANALYSIS SHOWS A THERMAL TROF IN ERN KY WHILE 12Z SOUNDINGS SHOWED A SHALLOW LAYER OF MOISTURE WITH INVERSION ABOVE. HIGH CLDS SPILLING IN FROM THE WEST AND A WEAK NE FLOW THIS AFTN MAY KEEP THE LO CLDS IN A BIT LONGER THAN ANTICIPATED ALTHOUGH 12Z RUC DOES CLEAR OUT THE CLDS BY 18Z. WILL KEEP AN EYE ON SATELLITE AND MAY SEND UPDATE FOR AFTN PERIOD IF LOW CLOUDS HANG ON TO LOWER MAXES. WHP NNNN ky SOUTHWEST...CENTRAL LOUISIANA AND SOUTHEAST TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 931 AM CST THU FEB 18 1999 COLD FRONT LOCATED FROM SPS TO ABI TO SJT. VIS SAT SHOW LOW CLDS AND FOG OVER MUCH OF FA. EXPECT FOG TO LIFT AND SKY TO BECOME SCT BY NOON. WV LOOP SHOWS S/WV MOVING INTO AR. LACK OF MSTR RETURN IN LOW- MID LVLS WILL PREVENT ANY SHRA WITH FROPA THIS EVENING. PW ACROSS REGION RUNNING AT 0.3 TO 0.4 INCHES. RUC MODEL TAKES FRONT THROUGH FA FROM 23Z TO 04Z...AM IN AGREEMENT WITH THIS SOLN. ONLY CHANGES TO FCST...TAKE OUT LOW CLDS AND FOG. OTHERWISE...CURRENT FCST LOOKS GOOD. 13 LCH 71/46 69/44 68 0000 LFT 70/46 67/42 67 0000 AEX 70/43 68/41 67 0000 BPT 74/46 70/44 69 0000 NNNN la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1020 AM EST THU FEB 18 1999 LATEST 88DS/SFC OBS SHOW PERSISTENT -SHSN NR LK SUP FM MN ARROWHEAD THRU CWA TO KANJ WITH GENERAL LGT NLY FLOW OVR LK SUP OUT OF SFC-H85 THERMAL TROF ACRS SRN ONTARIO. GREAT MAJORITY OF RADAR REFLECTIVITIES BLO 20 DBZ. 12Z GRB/APX SDNGS INDICATE INVRN 3K-4K FEET WITH DELTA-T BTWN INVRN BASE AND LK SUP IN 15-17 RANGE. WV LOOP AND H5 RAOBS INDICATE PRESENCE OF SUBTLE SHRTWV OVR SW ONTARIO...AND THIS SYS APPEARS TO BE ENHANCING SN A BIT. 00Z NGM AND 03Z MESOETA FCST A BIT OF H7 UVV AT F12 OVR WRN LK SUP. 12Z INL/YPL SDNGS BEHIND SHRTWV SHOW A MUCH DRIER ATMOSPHERE WITH SFC-BASED INVRNS...AND SFC DWPTS OVR SW ONTARIO AND NRN MN IN -10 TO -20 RANGE. LATEST IR SAT LOOP INDICATES SOME OF THIS DRY AIR IS ADVECTING EWD ACRS WRN LK SUP WITH BACK EDGE OF LO CLD MOVG STEADILY SEWD TOWARD IWD-ONT. THIS MOTION CONSISTENT WITH ESEWD MOTION OF SW ONTARIO SHRTWV AS FCST BY LATEST RUC MODEL AND AN INCRSD WLY LO LVL WIND COMPONENT TO S OF XPCTD TRACK. FCST CONCERN FOR TDAY IS EXTENT OF LES. 12Z RUC FCSTS ONTARIO SHRTWV TO BE DUE N OF ANJ BY 00Z. NGM INDICATES SWATH OF UVV WL END QUICKLY THIS MRNG AND THAT WLY COMPONENT OF LO LVL WIND WL INCRS INTO EARLY AFTN BEFORE LO LVL WINDS SWING BACK TO MORE NNE BY 00Z AS HI PRES BLDS ACRS SRN ONTARIO IN CONFLUENT WNWLY UPR FLOW FOLLOWING PASSAGE OF SHRTWV. WHAT THIS MEANS FOR FCST IS THAT LO LVL DRY AIR SHUD CONT TO MAKE INROADS INTO CMX-IWD. ALTHOUGH LO LVL WINDS WL LIKELY BCM MORE NLY AGAIN BEFORE DRY AIR REACHES BARAGA-MQT...LESS FVRBL NWLY TRAJECTORY WL TAPER OFF -SHSN FOR A TIME THIS AFTN THERE. ALGER COUNTY SHUD REMAIN FOCUS OF BETTER ACTIVITY. ALTHOUGH LES CHART SUGS UP TO 3" PSBL IN 6 HRS FOR XPCTD CONDITIONS...SHIFTING WINDS/ VERTICAL SHEAR AND LACK OF ANY BAND STRUCTURE IN CURRENT RADAR LOOPS SUG LESSER AMTS. LUCE COUNTY MAY SEE SOME PICKUP IN ACTIVITY WITH APRCH OF SHRTWV AND SOME NWLY FLOW. ANY PCPN OVR THE SRN ZNS SHUD END THIS AFTN AS SHRTWV SHIFTS EWD. KC NNNN mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 945 AM EST THU FEB 18 1999 SFC FRONT CURRENTLY LOCATED JUST WEST OF GREENVILLE WITH A LOW NEAR KENANSVILLE. LATEST RUC SHOWS LOW LIFTING NORTHEAST OF OUTER BANKS AFTER 15Z AND COLD FRONT PUSHING THROUGH THE OUTER BANKS AFTER 18Z. LATEST SATELLITE AND RADAR SHOWS BACK EDGE OF PRECIPITATION RAPIDLY LIFTING TO THE NORTHEAST. LIGHTNING PLOT SHOWS DIMINISHING LIGHTNING OVER THE LAND WITH MOST STAYING OFFSHORE OVER THE GULF STREAM. THINK THE RAIN SHOULD BE OVER IN THE INLAND COUNTIES BY THIS AFTERNOON. WILL ALLOW FOR AN ISOLATED SHOWER IN COASTAL COUNTIES. OUTER BANKS WILL CONTINUE TO SEE RAIN INTO THE AFTERNOON BEST INSTABILITY WILL BE RIGHT ALONG COAST...SO WILL ALLOW FOR THE CHANCE OF A THUNDERSTORM ON THE OUTER BANKS. TEMPERATURES WILL REMAIN STEADY IN THE UPPER 50S TO AROUND 60 ACROSS THE AREA. CWF: WILL CONTINUE SCA FOR EARLY THIS AFTERNOON. WILL END THE SHOWERS ON THE SOUNDS THIS AFTERNOON. .MHX...SCA COASTAL WATERS AND SOUNDS. BANDY NNNN nc SOUTHEAST TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 930 AM CST THU FEB 18 1999 VISIBILITIES IMPROVING OVER FOG COVERED AREAS AND FOG EXPECTED TO DISSIPATE LATE THIS MORNING WHEN LOW LEVEL FLOW WILL BECOME MORE WESTERLY. SURROUNDING 12Z SOUNDINGS INDICATE QUITE DRY AIR MASS (EXCEPT NEAR SURFACE) WITH GOOD CAPPING. RUC AND ETA PROGGED SOUNDINGS INDICATE LACK OF MOISTURE DESPITE FRONT MOVING ACROSS REGION LATER TODAY. WILL TAKE OFF MENTION OF PCPN EXCEPT FOR COASTAL WATERS. WILL MAKE MINOR ADJUSTMENTS TO 1ST PD AS WEST WINDS EARLY THIS AFTERNOON WILL PROBABLY SPIKE UP TEMPS. FRONT SHOULD APPROACH CLL ABOUT 3 PM...IAH AROUND 5 PM AND COAST NEAR 6 PM. 37/42 .HGX...NONE PRELIMS CLL BU 075 046/067 045/066 000 IAH BU 078 050/070 048/069 -00 GLS BU 071 054/067 057/067 1-0 NNNN tx EASTERN WASHINGTON AND NORTH IDAHO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WASHINGTON 900 AM PST THU FEB 18 1999 12Z ETA AND RUC INITIALIZED A LITTLE BETTER THAN THE LAST RUN WITH THE LOW OFF THE WA COAST. THE POSITION LOOKS GOOD...BUT THE INTENSITY IS STILL NOT DEEP ENOUGH...ABOUT A 3-4MB DIFFERENCE THAN WHAT THE BUOYS ARE SAYING. THIS HAS AN IMPACT ON THE PRESSURE GRADIENT ACROSS THE STATE WITH A STRONGER ERLY FLOW. THE SEA-EAT PRESSURE GRADIENT HAS STRENGTHENED TO 10 MB. WITH THE LOW STILL AT A LATITUDE TO OUR SOUTH...LOCAL STUDIES REVEAL THAT THE LOWER ELEVATIONS OF THE EAST SLOPES ARE VULNERABLE TO SIGNIFICANT SNOW TODAY. EAT HAS BEEN SNOWING FOR 2 / HRS AND SPOTTER REPORT INDICATE THAT IT IS ACCUMULATING. HAVE HOISTED A SNOW ADVISORY TODAY FOR THE WENATCHEE AREA... WATERVILLE PLATEAU AND OKANOGAN VALLEY FOR 1-3 INCHES OF SNOW TODAY. SNOW WILL ALSO FALL IN THE EAST SLOPES OF THE NORTH CASCADES...BUT BELIEVE SNOW AMOUNTS WILL REMAIN BELOW ADVISORY CRITERIA. PRECIPITATION HAVING A DIFFICULT TIME HEADING NORTH AND EAST...AS ONLY REPORTS SO FAR HAVE BEEN ACROSS THE SRN BASIN NEAR THE WARM FRONT. EXPECT PRECIPITATION TO GRADUALLY SPREAD ACROSS THE REST OF THE FORECAST AREA THIS AFTERNOON. STRONG ERLY DOWNSLOPE FLOW NOTED IN BOTH PDT AND PUW...WHICH WILL MAKE IT DIFFICULT TO GENERATE PRECIPITATION ACROSS MUCH OF SE WA...EXCEPT FOR THE BLUES. LIGHT AMOUNTS OF PRECIPITATION EXPECTED ACROSS ERN WA AND INTO N IDAHO. RLF. ...THE INFORMATION IN THIS PRODUCT CONCERNING WARNINGS AND FORECASTS IS VALID ONLY AT THE TIME OF ISSUANCE. THE LATEST WARNING AND FORECAST INFORMATION WILL BE FOUND IN THE APPROPRIATE PRODUCTS... GEG 041/033/042 672 CQV 042/031/044 673 S86 039/029/039 674 COE 042/032/043 672 WWP 038/028/039 674 LWS 050/037/049 772 MOS 041/030/043 EAT 037/030/046 861 .GEG...SNOW ADVISORY TODAY FOR WA ZN 41 43-44... NNNN wa