AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 1013 AM EST FRI FEB 18 2000 SYNOPSIS: LOOK FOR LOW PRESSURE TO MOVE FROM THE SOUTHERN PLAINS INTO THE OHIO VALLEY TODAY AS ARCTIC HIGH PRESSURE DRIFTS EAST INTO THE CANADIAN MARITIMES. THEN EXPECT THE LOW TO MOVE ACROSS SOUTHERN NEW ENGLAND FRIDAY NIGHT INTO SATURDAY. THIS SYSTEM WILL BRING ANOTHER ROUND OF MODERATE TO HEAVY SNOW TO MAINLY THE DOWNEAST PORTION OF THE REGION. TECHNICAL DISCUSSION: MAIN FOCUS THIS UPDATE IS WHAT TO DO W/WATCH ZNS29-30. WILL GO AHEAD & DROP WATCH ZNS15>17 & GO W/WINTER WX ADV AFT DISC IN HOUSE. LATEST RUC TRENDS W/ERLIER SHORT RNG MDLS W/KEEPING BULK OF MSTR ADVCTN FURTHER S TWD THE MID CST & OFFSHORE. ETA LOOKS OVERDONE W/QPF EVEN THO IT WAS VERIFYING W/PLACEMENT THRU 12Z. NEW 12Z GEM KEEPS HIEST QPF OFFSHORE. LIKE IMMED CST COULD RECEIVE HIEST QPF W/BULK REMINAING S & OFFSHORE. EVENT LOOKS TO BE DRAWN OUT THRU MID-AFTN SAT. FURTHER N...CHC -SN W/MINOR ACCUMS. IN THE SHORT TERM...AFT A COLD START...TEMPS SHOULD REBOUND NICELY W/PLENTY OF SUN ESP NRN ZNS. AM GOING TO ADJUST MAXS UP A NOTCH FOR ZNS 1>6 WHR MORE SUN SHOULD BE ARND. FURTHER S & E...WILL KEEP INCG CLDS. LIKE PRVS SHIFT/S IDEA OF BRINGING SN TO DOWNEAST/CST LATE W/SOME ACCUM. COASTAL WATERS: GLW IN PLACE & WILL FOLLOW SUIT. NO SIGNIFICANT CHGS TO BE MADE. .CAR...WINTER STORM WATCH TONIGHT INTO SAT ZNS29-30. GLW FOR COASTAL WATERS. JOE me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON 917 PM EST FRI FEB 18 2000 AFT A LULL IN PRECIP ERLIER THIS EVE...RADAR HAS FILLED IN AGN ACRS NRN HALF OF FA. SFC LOW PRES HAS BN HEADING NE THRU KY ALG ASSOC WRMFNT FOR LAST SEV HRS AND WAS MOVG INTO SRN OH AT 02Z. TSRAS HV BN OCCURRING AHD OF THE LOW IN WRM SECT OVR WRN WV INTO KY. THE RA AREA OVR NRN FA WAS ALG ERN EXTENT OF WRMFNT. IN PA FZRA WAS OCCURRING N OF WRMFNT. TEMPS HV BN CLIMBING SLOWLY OVR THE FA THIS EVE. SRN PTNS OF FA WERE IN L/M 40S AT 02Z...ERN PANHANDLE WV TEMPS HAD RISEN INTO L50S. TEMPS AVGD IN M30S OVR NRN FA. 00Z LWX SDNG INDCTD STG INVERSION FM ABT 900 TO 950 MB. ETA AND RUC HAD GUD HANDLE ON SYS AT 00Z IN TERMS OF TEMP PROFILES. BOTH KEPT MUCH OF FA STABLE THRU 12Z SAT. BELIEVE BEST CHC OF TSRA/S WILL BE FM SHEN VLLY WWD WHERE SFC TEMPS AND DWPTS WL BE HIEST AND INSTAB GREATEST AS SYS PROGRESSES E. WL PROB HV SOME DOWNPOURS AS CDFNT APPCHS BUT GIVEN THAT SYS WL BE PROGRESSIVE AND FFG HI...DON/T FORSEE ANY FLD THREAT. SO...OVERALL FCST IN GUD SHAPE. WL TRIM BACK TSTM MENTION TO SHEN VLLY WWD AND ADJUST TEMPS HIER WHERE NECESSARY. .LWX...SMALL CRAFT ADVISORY POTOMAC AND NRN CHES BAY ARTHUR md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1105 PM EST FRI FEB 18 2000 WARNING HEADLINE ALLOWED TO EXPIRE AT 1100 PM EST. LATEST RADAR TRENDS AND MODEL DATA (00Z ETA AND 02Z RUC) SUGGEST ACCUMULATING SNOW WILL END BY 100 AM IN EXTREME SOUTHEAST FORECAST AREA. OTHERWISE...FORECAST REMAINED UNCHANGED WITH CLEARING TOWARD DAYBREAK FOR NRN COUNTIES AND JUST AFTER DAYBREAK SRN COUNTIES. .GRR...NONE. GREENE mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1036 PM EST FRI FEB 18 2000 MAIN PROBLEM FOR TONIGHT IS CLOUD COVER...AS SNOWFALL ALONG DEFORMATION AXIS NORTH OF VORTICITY CENTER ROTATING ACROSS NORTHERN IN REMAINS WELL TO THE SOUTH. 00Z APX/GRB SOUNDINGS FAIRLY MOIST BELOW SUBSIDENCE INVERSION LOCATED AROUND 850MB. TREND IN FOG LOOPS HAS BEEN A SLOW INCREASE IN CLOUD COVER ACROSS LAKE SUPERIOR AND CENTRAL/EASTERN UPPER WHERE CLOUD COVER HAS JUST ABOUT OVERSPREAD CHIPPEWA COUNTY. FARTHER SOUTH...LAYERED LOW/MID CLOUD REMAINS IN PLACE OVER NORTHERN LOWER. EXTRAPOLATION WOULD TAKE MID CLOUD OUT OF THE SOUTHEAST CORNER OF THE FORECAST AREA BETWEEN 06-08Z...LEAVING BEHIND LOW ST/SC. SURFACE OBS AND SATELLITE SHOW SOME BREAKS IN LOW CLOUDS OVER NORTHERN PARTS OF LAKES MICHIGAN AND HURON...WITH SOME CLEARING REPORTED FROM ACB-PLN AND LIKELY EXTENDING AROUND TOWARD ROGERS CITY. 12Z MODEL RUNS POORLY HANDLED LOW LEVEL MOISTURE FOR TONIGHT...DRYING THINGS OUT BY 00Z WHICH HAS NOT OCCURRED. SEVERAL FACTORS TUGGING AT EACH OTHER TONIGHT...GOOD MID LEVEL SUBSIDENCE HELPING TO PUSH INVERSION DOWN ALONG WITH ANTICYCLONIC FLOW BENEATH INVERSION TRYING TO DRY THINGS OUT. MEANWHILE...BOUNDARY LAYER COOLING WILL HELP TRY AND KEEP LOW LEVEL RH UP...PARTICULARLY ONCE MID DECK MOVES OUT..ALONG WITH SHALLOW INSTABILITY OVER THE LAKES. 00Z RUC AND EARLY LOOK AT THE NEW ETA IMPLY BEST SHOT OF CLEARING OVER NORTHEAST OVERNIGHT...WHICH LOOKS REASONABLE GIVEN MAINLY NORTHEAST LOW LEVEL FLOW OVERNIGHT AND CLEARING OVER SOUTHERN ONTARIO. THE UPDATE WILL KEEP EASTERN UPPER MOSTLY CLOUDY OVERNIGHT...ALONG WITH THE MENTION OF SOME PATCHY FOG. ACROSS NORTHERN LOWER...HAVE CONTINUED EARLIER FORECAST TREND OF DECREASING CLOUDS EAST OF I-75...ALTHOUGH WITH POTENTIAL FOR SOME LAKE SC DRIFTING IN WORDED SOUTHEAST PORTION OF FORECAST AREA AS JUST DECREASING CLOUDS. FOR NORTHWEST LOWER...A BIT MORE COMPLICATED. SUSPECT THAT AS LOW LEVEL WINDS TURN MORE NORTHERLY OVERNIGHT...SOME OF THE CLOUDS OVER EASTERN UPPER MAY DRIFT SOUTH. HOWEVER...ONCE THE MID CLOUDS MOVE OUT WILL PROBABLY SEE SOME PERIODS OF CLEARING...ESPECIALLY NORTH OF M-72. SO THESE AREAS WENT VARIABLE CLOUDINESS. SOUTH OF M-72 JUST KEPT FLAT OUT MOSTLY CLOUDY. DESPITE CHANGES IN CLOUD COVER FORECAST...KEPT MOST TEMPERATURE FORECASTS PRETTY MUCH THE SAME GIVEN THE LIGHT WINDS AND POTENTIAL FOR PERIODS OF CLEARING OVERNIGHT. UPDATED ARBZFPAPX WILL BE OUT BY 0340Z. .APX...NONE. JPB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1015 PM EST FRI FEB 18 2000 FCST FOCUSES ARE LOW CLOUDS...FOG...AND OF COURSE...TEMPS. SFC ANALYSIS AT 02Z SHOWS UPR MI UNDER THE INFLUENCE OF BROAD RIDGE OF HIGH PRESSURE. RIDGE IS SQUEEZED BETWEEN MODERATE ARCTIC FRONT TO NORTH OVR CENTRAL MANITOBA AND WX MAKING LOW PRESSURE OVR SRN OHIO TO SOUTH. RIDGE STRETCHES FM A 1027MB SFC HIGH MVG INTO SERN NEB TO ANOTHER WEAKER HIGH OVR WRN QUEBEC. MAIN RESULT FOR THE FA IS LGT AND VAR SFC FLOW AND LITTLE HORIZONTAL/VERTICAL ADVECTION TO PUSH LOW LEVEL MOISTURE OUT OF THE AREA. MOST PREVALENT LOW LEVEL MOISTURE IS OVR ERN 2/3 OF THE YOOP AS DIPICTED BY 11-3.9 VIS SAT AND LOCAL METARS REPORTING BKN CIGS AOB 3KFT EAST OF A IMT TO MQT LINE...HOWEVER RECENT SAT TRENDS BEGINNING TO SHOW CLOUDS INCREASING OVR REMAINING FA AS WELL. BOTH 00Z RUC AND 18Z ETA SHOWING A G R A D U A L DRYING OF THE H925 TO H875 LAYER TONIGHT AS THE ETA HAS THE H875 RH AOB 60 PERCENT CONTOUR ONLY REACHING IRON COUNTY BY 12Z. IMMEDIATELY ABOVE THIS LAYER AT 850MB THINGS ARE BECOMING VRY DRY WITH 00Z INL RAOB SHOWING A DWPT DEPRESSION OF 11C AND ETA PROGGING RH AOB 30 PERCENT OVR FA BY 09Z. WITH VRY LITTLE IN THE FORM OF WINDS TO MIX THOUGH...IT APPEARS THE DRIER AIR WL STAY AT BAY. BACK TO SFC...FOG ALSO BECOMES A POSSIBILITY WITH LOW LEVEL MOISTURE IN PLACE AND LGT SFC GRADIENT...HOWEVER THINK INCREASING GRADIENT FM ADVECTING ARCTIC FRONT LATE (BLYR WIND INCREASING TO 5 TO 10 KTS FA WIDE) WL KEEP MOST PLACES FROM SEEING ANY DENSE FOG... ALTHOUGH SOME THIN PATCHY FOG IN FAVORED AREAS (KSAW) UNTIL THEN IS DEFINETLY NOT OUT OF THE QUESTION. TEMPS WL BE A CHALLENGE AS MINS NEAR ZERO WON'T OCCUR IF CLOUDS STAY ALL NIGHT LONG...A BIG IF WITH THE DRY AIR TRYING TO INTRUDE. RIGHT NOW WL GO WITH MORE CLOUDS FOR ERN HALF OF UPR MI...THUS WARMER TEMPS WITH BETTER CHANCE FOR DRYING...MIXING...AND CLOUDS BREAKING UP OVR WEST...YIELDING LOWER TEMPS. .MQT...NONE. JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 710 PM EST FRI FEB 18 2000 WILL UPDATE BASED ON RADAR TRENDS AND LATEST RUC...TO DROP NORTHERN TWO TIERS FROM WARNING/ADV AND BUMP INGHAM AND JACKSON FROM ADV TO WARNING. TWEAKED STORM TOTALS TO ACCOUNT FOR CURRENT REPORTS AND REVISED EXPECTED AMOUNTS. .GRR...WINTER STORM WARNING. ...MUSKEGON...KENT...MONTCALM...GRATIOT COUNTIES ON SOUTH THROUGH THIS EVENING. OSTUNO mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1130 AM EST FRI FEB 18 2000 LETTING CURRENT FORECAST RIDE WITH ONLY MINIMAL CHANGES MADE...MAINLY TO LOWER SNOWFALL TOTALS BUT STILL AT OR ABOVE WARNING CRITERIA. STILL ANTICIPATING THE LOW PRESSURE CENTER TO TRACK SOUTH OF MICHIGAN THROUGH THE OHIO RIVER VALLEY. WITH LOW CENTER PROGRESSION...LATEST RUC SOUNDINGS AND CRITICAL THICKNESS VALUES REVEALING COLD ENOUGH TEMPS TO PULL ANY MENTION OF MIX PCPN FROM SOUTHERN COUNTIES. FEEL BEST CHANCE OF MIX PCPN WILL BE SOUTH OF GRR CWA. SNOWFLAKE SIZE AND GUSTY WINDS HAS HELPED TO PROHIBIT ANTICIPATED SNOW ACCUMULATION FOR THIS TIME FRAME...HOWEVER WITH TEMPS EXPECTED TO RISE TO AROUND 30 A WETTER SNOW WOULD HELP ACCUMULATION AMOUNTS. LATEST RUC 295K ISENTROPIC ANALYSIS SUGGESTS SNOW WILL CONTINUE THROUGH THIS AFTERNOON AND END LATER THIS EVENING. MIXING RATIOS OF AT LEAST 3 TO 4 G/KG OVER SRN CWA WITH A TOTAL TIME FRAME JUST UNDER 12 HOURS WOULD SUPPORT AT LEAST 6 INCHES OF TOTAL ACCUMULATION BY THIS EVENING. LOOKING UPSTREAM AT OBSERVATIONS UNDER THE APPROACHING DEFORMATION ZONE SNOWFALL RATES CONTINUE STRONG AND SHOULD REMAIN STRONG AS THIS SLIDES INTO WEST MICHIGAN THIS AFTERNOON. LATEST VIS SAT IMAGERY ALSO SHOWS A CONVECTIVE LOOKING AREA OF PCPN MOVING INTO NORTHERN IL WHICH WILL CONTINUE A NORTHEAST TRACK INTO WEST MICHIGAN AND HELP INCREASE SNOWFALL RATES. DISTANCE SPEED CALCULATIONS PUT THIS AREA INTO GRR CWA JUST AFTER 19Z. NORTHERN SECTIONS OF CWA WILL HAVE A HARDER TIME REACHING ADVISORY/WARNING CRITERIA BY THE TIME THE SNOWFALL STOPS THIS EVENING...HOWEVER WITH A SLOW MOVEMENT AND WHAT IS UPSTREAM DECIDED TO LEAVE FORECAST AS IS. MCINERNEY .GRR...WINTER STORM WARNING. ..OCEANA...NEWAYGO...MECOSTA...ISABELLA COUNTIES ON SOUTH THROUGH THIS EVENING. SNOW ADVISORY FOR MASON...LAKE...OSCEOLA...AND CLARE THROUGH THIS EVENING. mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 905 PM EST FRI FEB 18 2000 LOCAL AREA RADARS SHOW THE PCPN REALLY BREAKING UP THIS EVENING AS A NARROW BAND OF DRY AIR IN MID LVLS SEEN ON WATER VAPOR IMAGERY MOVES IN. SFC PRESS FALLS STILL FAIRLY RESPECTABLE OVR CAPE COD AND STILL INDICATING A JUMP IN SFC LOW TO COAST. MAPS ANALYSIS SHOWS TWO AREAS OF LOW PRESS...ONE IN SWRN PA AND THE OTHER FORMING S OF LI. UPPER LVL SHT WAVE DRIVING THIS SYSTEM STILL FAR TO THE W OVR NRN IL/IN AND LATEST RUC FCST TRACKS THIS WAVE ACRS NRN PA/SRN NY LATER TNGT/EARLY TMW MORNING. ANOTHER AREA OF LGT TO MOD SNOW ASSOCD WITH THIS WAVE OVR SRN MI AND NRN IL/IN SO EXPECT SNOW TO MOVE BACK INTO FA LATER TNGT. WILL KEEP WSW GOING FOR THE FA AREA OVERNIGHT DESPITE THE BREAK IN THE PCPN RIGHT NOW FOR ADDITIONAL ACCUMS WHEN SECOND AREA ARRIVES. THERE STILL LOOKS TO BE A GOOD POTENTIAL FOR FREEZING RAIN OVER SRN CWA LATER TNGT. THE HEAVIEST RAIN WILL MOST LIKELY REMAIN S OF CWA BUT I THINK THERE WILL BE A GOOD PERIOD OF FREEZING RAIN TOWARD SUNRISE OVR SRN CWA AS THE IL/IN SHORT WAVE MOVES THROUGH. IF THE SECONDARY LOW CONTINUES TO STRENGTHEN OVER LI TONIGHT THIS WILL INDUCE A STRONGER NLY FLOW TO KEEP COLD AIR LOCKED IN AND I THINK THIS WILL LIMIT ANY CHANCES FOR THE FREEZING RAIN TO CHANGE OVER TO RAIN. ONCE THE COLD FRONT MOVES THROUGH MID LVLS WILL COOL OFF FOR THE FREEZING RAIN TO CHANGE BACK TO SNOW. SO HAVE ADJUSTED SECOND PD WORDING FOR THIS SCENARIO. WILL KEEP FFA GOING OVERNIGHT FOR POTENTIAL ICE JAMS BUT LATEST LOOK AT RIVER GAUGES SHOWS THINGS ARE QUIET...WHICH IS GOOD. .BGM...WSW TONIGHT ALL AREAS. FFA NYZ0062 PAZ0040-043-044-047-048 HOLMES ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 1005 PM EST FRI FEB 18 2000 WEDGE PERSISTS N CWA/UPSTATE AND INTO NE GA. LT WINDS/SKC OVR REMAINDER CWA. CURR TEMP CAE NR FCST MIN. IN FACT...SIG TEMP GRADIENT ACRS CWA. WITH THE LT WINDS CURR...WEDGE MAY BE TRYING TO MV SLIGHTLY BACK S. MID LVL CLDS APPRCHG CWA...AND SATL EXTRAP BRINGS THEM IN WITHIN THE NEXT HOUR OR SO. LTST MDLS STILL INST IN INCR PRESS GRAD/WIND DURG NT. CAE VWP INDICATING INCR IN 1K WIND DURG PAST HR. RUC LIFTS WEDGE NEWD THRU 12Z...WHILE 00Z ETA KEEPS WEDGE IN PLACE OVRNT. THUS...TEMPS ACRS PORTIONS OF CWA MAY HAVE REACHED MIN VALUES FOR THE NT ALREADY. WILL FCST NR STEADY OR SLOWLY RISING TEMPS TON...AND WL MENTION BECMG MSTLY CLDY. AS FAR AS PCPN GOES...RADAR INDICATING BAND SH/TSRA HAS REACHED E KY/CENT TN STRETCHING SW INTO N ALA. EXTRAP BRINGS IT IN HERE ARND 09-12Z...BUT LTST RUC AND NEW 00Z ETA KEEP PCPN TO OUR W THRU 12Z. QUES IS HOW MUCH OF IT HOLDS TOGETHER. MORE STABLE AIR IN PLACE TO THE EAST OF CURR CONVEC...NOTED ON LTST SPC DAY 1. SPC HAS GENERAL TSRA INTO UPSTATE TIL 12Z. LTST MDLS KEEP STRONGER UPPR JET/DIVG...GREATER INSTABS...AND 850 JET TO OUR N OVRNT. SO...WITH TIMING OF ACTIVITY LATE PLUS POTENTIAL FOR SOME DISSIPATION...THINK CURRENT 20 POP TON STILL OK...AND WILL WORD TOWARD DAYBREAK. MAY BUMP UP PIEDMONT POP TO 30 SINCE GREATER POTENTIAL FOR ACTIVITY TO THE N...PLUS ACTIVITY WOULD REACH THAT AREA FIRST. .CAE...NONE. sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 950 PM EST FRI FEB 18 2000 KIND OF A WEIRD FORECAST SITUATION ACROSS THE REGION OVERNITE...WITH COLD AIR WEDGE CURRENTLY IN ITS DEATH THROES. BEEN WATCHING THE DEEP CONVECTION APPROACHING FROM MIDDLE TN AS WELL...NOW PUSHING E ACROSS THE CUMBERLAND PLATEAU. THERE ARE A NUMBER OF CONCERNS OVERNITE...THE MAIN ONE BEING THE APPROACHING CONVECTION. 18Z ETA AND 00Z RUC CONTINUE THE MODEL TREND OF MOVING THE BEST UPPER SUPPORT FOR CONVECTION ON OFF TO THE NORTH. IN RESPONSE...THE MODELS PRECIPITOUSLY WEAKEN (PUN INTENDED) THE CONVECTION AS IT MOVES OVER THE MOUNTAINS LATE THIS EVENING... WITH ALMOST NOTHING LEFT OF THE PRECIP AS IT DIES OVER THE COOL POOL EAST OF THE MOUNTAINS AFTER MIDNIGHT. THE CURRENT ZONES HAVE THIS SCENARIO IN MIND. IF IT BECOMES MORE APPARENT THAT A LARGE AREA OF PRECIP WILL SPREAD OVER THE MOUNTAINS LATER THIS EVENING...MAY RAISE PRECIP CHANCE INTO CATEGORICAL RANGE...BUT SEE NO REASON TO SIGNIFICANTLY ALTER PRECIP CHANCES E OF THE MOUNTAINS AT THIS TIME. THE NEXT PROBLEM IS DENSE FOG OVER EXTREME NE GA AND WRN SC...WHERE VISIBILITIES HAVE BEEN DOWN TO 1/4 MILE IN SOME LOCATIONS. HAVE CONSIDERED GOING WITH A DENSE FOG ADVISORY FOR THIS AREA...BUT IT WOULD APPEAR THAT DENSE FOG WILL NOT BE WIDESPREAD ENOUGH OR OF A LONG ENOUGH DURATION TO WARRANT AN ADVISORY. VISIBILITIES HAVE BEEN VARIABLE ACROSS MUCH OF THE AREA...AND SHOULD IMPROVE IN AN HOUR OR TWO AS MORE PRECIP APPROACHES THE AREA. WILL...HOWEVER...CONTINUE TO MENTION PATCHES OF DENSE FOG IN SHORT TERM FORECASTS...AND WILL ALSO ADD IT TO THE ZONES. NEXT UP...TEMPS. WITH THE WEDGE TRYING TO BREAK DOWN...WE SHOULD ACTUALLY SEE TEMPS CLIMBING A BIT OVERNITE. HOWEVER...TEMPS E OF THE MOUNTAINS ARE NOT YET IN THE RANGE ADVERTISED IN THE ZONES...WHICH BEGS FOR A TWEAK IN WORDING. WILL CONSIDER LOWERING THAT RANGE TOO...BASED ON THE LATEST LAMP GUIDANCE. FINALLY...THE WIND ADVISORY FOR THE MOUNTAINS STILL LOOKS TO BE ON TRACK. GRADIENT WINDS CONTINUE TO STRENGTHEN ACROSS THE MOUNTAINS AS LOW LEVEL JET MOVES IN. WINDS AT FLAT TOP MTN ARE 29G40 AT LAST REPORT...SO THE ADVISORY WILL BE CONTINUED. .GSP...WIND ADVISORY FOR ALL MTN ZONES TONIGHT. MOORE sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 957 AM EST FRI FEB 18 2000 DISC: 14Z SFC ANALYSIS SHOWS HI PRES CONT TO WEDGE SWD ACRS THE STATE. TROF/CSTL FRONT JUST OFF THE CST. SATELLITES SHOWS LOTS OF CLDS ACRS THE STATE THIS MORNING. ALTHOUGH...SOME SUN ALNG THE S CSTL AREAS. 00Z MODELS AND MORNING RUC INDICATE THAT WEDGE WL BREAK DOWN DURING THE AFT. HOWEVER...THE USUAL TREND IS TO BRING WINDS ARND FROM NE TO SE/S TO QUICKLY. ETA MODEL LIS SHOW WEDGE OF STABLE AIR CONT ACRS MUCH OF THE AREA...BUT SLOWLY ERODES FM THE SE DURING THE AFT/EARLY EVENING. VWP SHOWING THE LAYER OF COLD AIR VERY THIN...LESS THAN 1000 FT. TEMP CURRENTLY RUNNING FM THE MID/UPR 30S N TO AROUND 50 S. WITH AFT PACKAGE...WL SLOW DOWN THE TREND TWRD BREAKDOWN OF WEDGE AND ADJUST TEMPS DOWNWARD IN MOST AREAS...ESP N AND W. WITH SOME CLRNG SKIES TRYING TO PUSH WWD ACRS THE SRN PTN OF THE STATE...WL BE THE MOST OPTIMISTIC THERE WITH AFT TEMPS. WL CONT WITH SOME SML CHC FOR -RA/-SHRA DURING THE AFT. ALTHOUGH MOISTURE CONT TO THIN...ESP OVR THE SERN AREAS...SOME WK ISENTROPIC LIFT STILL OCCURING ACRS THE AREA. .CAE...NONE. LCV sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 915 PM EST FRI FEB 18 2000 COLD WEDGE IS ERODING. WINDS HAVE COME AROUND TO THE SW IN MANY LCATIONS. LYH WENT FM 33 AT 19Z TO 40 DEG AT 00Z. 00Z SOUNDINGS CAME IN WITH VERY STG WINDS JUST ABV THE SFC. RNK SOUNDING SHOWED VERY HIGH HELICITY...BUT SHEAR WAS UNIDIRECTIONAL. WATCHING THE TSRA IN WV AND KY...ESTIMATE STORMS SHUD REACH WRN COUNTIES BETWEEN 03-05Z. RUC STILL HAS +10 85H DEW POINTS FEEDING INTO THE STORMS AT 06-09Z. HELICITY AND MOISTURE FEED WILL HELP STORMS...BUT MOUNTAINS AND STABLE SFC LAYER SHUD WEAKEN THE STORMS. ONLY MINOR CHANGES IN TIMING OF PCPN AND TEMPS NEEDED FOR FIRST PERIOD. NO CHANGES TO REST OF FCST. .RNK VA...NONE. WV...NONE. NC...NONE. AMS va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 255 PM EST FRI FEB 18 2000 BEST UVV AND MOISTURE FOCUSED ALG WRMFNT ACRS S OH. LOW TO PASS ACRS S OH THIS EVENING AND SW/V PROGGED OVHD JUST AFT 06Z. CONVECTION ACRS S OH WL BLOCK BEST MOISTURE BUT AS SW/V AND LOW GET CLOSER PCPN WL EXPAND AGAIN LATE THIS AFTERNOON AND EVENING. SFC WND HAS COME NE ALREADY BUT RUC SHOWS WARMING ALOFT TO MAX OUT BETWEEN 00Z-03Z. HARD TO PIN DOWN WHERE SFC FREEZING LINE WL FLUCTUATE TO. WITH SFC FLOW FM NE TEMPS SHUD BEGIN TO COME DOWN BY SUNSET. WITH LIMITED QPF WARNINGS ARE NO LONGER NECESSARY BUT WL POST WINTER WEATHER ADVISORY FOR COUNTIES CURRENTLY AT FREEZING AND THEN ONE TIER SOUTH TO MFD AND CAK AND WARREN ALLOWING FOR SOME COOLING EARLY TNGT. PCPN SHUD STAY LGT SNOW TOL AREA AND WL NOT REQUIRE AN ADVISORY SINCE ONLY AN INCH OR TWO LIKELY TONIGHT. CHANGE BACK TO SNOW ENTIRE FCST AREA FM NW TO SE 02Z-08Z. WRAP AROUND CLOUDS/FLURRIES OR LGT SNOW INTO SAT. SECOND COLD FNT DROPPING S ACRS GRTLKS BY SUN MORN. H8 TEMPS NOT COLD ENUF FOR LAKE EFFECT SNOW AND NOT MUCH MOISTURE AVAILABLE BUT INVERSION PROGGED TO SET UP AROUND 850 MB AND SOME SC AND FLURRIES MAINLY NE OH AND NW PA. .CLE...WINTER WEATHER ADVISORY N 1/4 OH AND NW PA TNGT KOSARIK oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 229 AM EST SAT FEB 19 2000 WEDGE BEGINNING TO ERODE ACROSS THE MTNS AND FOOTHILLS. KAVL 59...KMRN 61...KFQD 54...KHKY 55. REST OF THE CWFA IN THE 40S. SFC FNT ACROSS E TN AND IS ALREADY SLOWING DOWN ACCORDING TO MSAS POTENTIAL TEMPS. STILL A DECENT AMOUNT OF CONVECTION ALONG THE FNT...HOWEVER MUCH OF THE PRECIP HAS BEEN FALLING APART AS IT MOVES INTO THE WEDGE AIR MASS. MOISTURE AND PRECIP SHOULD BEGIN TO OUTRUN THE FNT THIS MORNING AS IT GETS HUNG UP IN THE MTNS. DO EXPECT A BAND OF CONVECTION TO MOVE ACROSS THE CWFA THIS MORNING. WILL WAIT TILL ISSUANCE TIME TO DETERMINE NEED FOR POPS IN WRN SECTIONS. FNT WILL BE SLOW TO CROSS THE AREA AS FCST BY RUC AND ETA POTENTIAL TEMP PLOTS. HOWEVER AS MENTIONED ABOVE...MOISTURE AND UPPER SUPPORT WILL OUTRUN THE FNT. DO NOT EXPECT MUCH REDEVELOPMENT ALONG THE FNT IN MY CWFA GIVEN LACK OF MOISTURE AND WRLY WINDS. SHOULD SEE A RETURN TO SOME SUNSHINE BY AFTERNOON. THE SLOW FRONTAL MOVEMENT AND WRLY WINDS WILL ALLOW TEMPS TO RISE QUITE A BIT ACROSS THE CWFA SINCE LOW LEVEL CAA WILL HOLD OFF UNTIL LATE DAY. WILL GO ABOVE MOS FOR HIGHS BUT BELOW LOCAL ETA EQUATIONS WHICH GIVE GSP 71. WINDS WILL NOT BE AS HIGH TODAY AS H85 JET MOVES EAST SO WILL ALLOW WIND ADVISORY OVER THE MTNS TO EXPIRE. CLEAR TONIGHT WITH GOOD CAA BUT WINDS WILL REMAIN UP A LITTLE. EXCEPTION WILL BE THE NRN MTNS WHERE SCT SNOW SHOWERS WILL DEVELOP IN THE WRAP AROUND MOISTURE...NWLY FLOW AND CAA. EXPECT THE SNOW SHOWERS TO TAPER OFF SUNDAY. SUNNY WITH LESS WIND ELSEWHERE SUNDAY BUT COOLER AS HIGH PRESSURE BEGINS TO MOVE IN. PRELIM NUMBERS AVL 56/30/50 100 CLT 68/31/58 400 GSP 67/31/58 100 .GSP...NONE. RWH sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 335 AM CST SAT FEB 19 2000 LATEST SURFACE ANALYSIS HAS THE COLD FRONT...STRETCHING FROM EASTERN TN THROUGH SOUTHERN MS AND LA TO THE TX GULF COAST...BEFORE BECOMING NEARLY STATIONARY ACROSS THE FRONT RANGE OF THE ROCKIES. A LARGE DOME OF HIGH PRESSURE IS POISED TO OUR NORTHWEST OVER THE CENTRAL PLAINS. LATEST LOW CLOUD/FOG LOOP (11-3.9 MICRON IMAGERY) SHOWS LOW CLOUDS ACROSS THE ENTIRE CWFA EARLY THIS MORNING. THIS LOW LEVEL MOISTURE APPEARS TRAPPED UNDER AN INVERSION...WHICH IS EVIDENT ON THE KLZK 00Z SOUNDING. THESE CLOUDS WILL BE THE FIRST PROBLEM OF THE DAY. THE 06Z RUC AND 18Z MESO ETA INDICATE BOUNDARY LAYER RELATIVE HUMIDITIES TO REMAIN ABOVE 60 PERCENT AT LEAST THROUGH 18Z TODAY. 05Z LAMP DATA INDICATES LOW CLOUDS WILL HOLD ON TO BETWEEN 16 TO 18Z TODAY AND THE NEW 08Z LAMP DATA INDICATES THAT THE CLOUDS WILL NOT BREAK UNTIL 18 TO 19Z. FRH66 INDICATES THAT THE ETA R1 (LOW LEVEL RH) DOES NOT GO BELOW 60 PERCENT ALL DAY...WHILE THE FRHT66 INDICATES THE NGM R1 VALUE WILL DROP BELOW 60 PERCENT BY AROUND 18Z. AS MENTIONED ABOVE 00Z KLZK SOUNDING SHOWED A LOW LEVEL INVERSION. FORECAST MODEL SOUNDINGS OFF THE ETA...NGM...MESO ETA AND RUC ALL INDICATE A VERY SLOW BREAK DOWN OF THE INVERSION TODAY. WITH ALL THIS IN MIND...I HAVE DECIDED TO USE THE PHRASEOLOGY OF "MORNING CLOUDINESS...THEN PARTLY CLOUDY THIS AFTERNOON." THIS ACTUALLY MAY BE A BIT OPTIMISTIC...ESPECIALLY IF THE ETA HOLDS TRUE. THIS CLOUDINESS WILL ALSO HAVE AN AFFECT ON THE FORECAST HIGHS TODAY. ORIGINALLY THOUGHT THAT THE FWC AND FAN NUMBERS WERE TOO COOL (I.E., FWC OF 52 VS FAN 50 FOR KLIT)...BUT WILL PROBABLY GO AT OR SLIGHTLY BELOW THE FWC MOS MUNMBERS. IN FACT...THE NEW 08Z LAMP ESTIMATED HIGH FOR KLIT IS 49. IN THE UPPER LEVELS...THE SHORT WAVE...THAT MOVED ACROSS SOUTHERN MO ON FRIDAY...WAS LOCATED ACROSS NORTHERN IL AT 00Z. A NORTHERN STREAM SHORT WAVE WAS ALSO ANALYZED ACROSS NORTHEAST WY AND THE WESTERN DAKOTAS. A CLOSED LOW WAS ANALYZED OVER THE EASTERN PACIFIC APPROACHING THE CA COAST. COMPARING THE MODEL INITIALIZATION WITH THE 00Z/500 MB ANALYSIS AND WATER VAPOR IMAGERY INDICATES THE MODELS INITIALIZED WELL. I THEREFORE WILL USE A COMPOSITE FOR THIS FORECAST PACKAGE. THROUGH 24 HOURS...THE TWO SHORT WAVES OVER THE EAST WILL HELP TO CARVE OUT A BROAD TROUGH WITH RIDGING BUILDING OVER THE ROCKIES. THE NGM AND THE AVN ARE VERY SIMILAR WITH HAVING THE CLOSED LOW OFF THE SOUTHERN CA COAST AT THIS TIME. THE ETA IS WEAKER AND HAS ONLY A BROAD TROUGH ACROSS THE SAME AREA OF THE EASTERN PACIFIC. WITH THE BUILDING TROUGH TO THE EAST AND RIDGE TO THE WEST...THE UPPER AIR FLOW ACROSS AR WILL BECOME NORTHWESTERLY. BY 48 HOURS...A HIGHLY AMPLIFIED PATTERN WILL DEVELOP ACROSS THE COUNTRY WITH A VERY DEEP TROUGH ACROSS THE EASTERN US...THE RIDGE WILL BUILD EASTWARD OUT OF THE ROCKIES AND INTO THE PLAINS AND A DEEP TROUGH COMING OUT OF THE GULF OF ALASKA WILL MOVE INTO THE EASTERN PACIFIC OFF THE WEST COAST. THE CLOSED LOW WILL WEAKEN GREATLY...AS IT TRIES TO MOVE OVER THE RIDGE ACROSS THE ROCKIES/PLAINS. AR WILL REMAIN NORTHWEST FLOW. MOST OF THE SHORT WAVE ENERGY WILL REMAIN TO THE NORTH THROUGH THE 48 HOUR PERIOD. MEAN RELATIVE HUMIDITIES WILL REMAIN BELOW 50 PERCENT THROUGH THE SHORT RANGE. AT THE SURFACE...A HIGH PRESSURE WILL BUILD IN FROM THE NORTHERN AND CENTRAL PLAINS TODAY WITH A REINFORCING HIGH BUILDING IN FOR SUNDAY. RETURN FLOW WILL BEGIN BY SUNDAY AFTERNOON WITH THE HIGH LOCATED JUST TO OUR EAST BY 00Z MONDAY. IN TERMS OF PRECIPITATION...NO PRECIPITATION THROUGH THE SHORT RANGE PERIOD. IN TERMS OF TEMPERATURES...I USED A COMPROMISE BETWEEN THE WARMER FWC AND THE COOLER FAN MOS GUIDANCE. ...EXTENDED... ...AVN 48-72 HOUR TIME PERIOD... THE 500 MB RIDGE WILL CONTINUE TO BUILD EASTWARD ACROSS THE STATE ON MONDAY. TWO SHORT WAVES WILL BE EJECTED EASTWARD OUT OF THE TROUGH ACROSS THE WEST COAST AND MOVE INTO THE STATE DURING THE AFTERNOON HOURS. MEAN RELATIVE HUMIDITIES INCREASE TO ABOVE 60 PERCENT OVER THE NORTHERN TWO-THIRDS OF MY CWFA. AVN TIME SECTION AT KHRO IS THE ONLY PLACE THAT MOISTENS THE LAYER ENOUGH TO GET ANY RAIN AND THAT IS AT THE END OF THE PERIOD (I.E., 72 HOURS-00Z TUESDAY). FAN POPS DO HAVE 20 PERCENT AT BOTH KFSM AND KSGF FOR MONDAY. PREVIOUS FORECAST HAD ONLY PARTLY CLOUDY. I WILL ADJUST THIS TO INCREASING CLOUDS...BUT LET FUTURE SHIFTS DECIDE WHETHER TO INCLUDE ANY POPS. ...MRF DAYS 4 AND 5... QUICK LOOK AT THE MRF...SHOWS THE TROUGH OFF THE PACIFIC COAST AT 48 HOURS WILL MOVE EASTWARD AND STRENGTHEN OVER THE CENTRAL PLAINS ON WEDNESDAY. IT LOOKS LIKE RIGHT NOW IT WILL BRING ANOTHER BOUGHT OF SEVERE WEATHER WITH IT. THE TRACK OF THE SURFACE LOW WILL BE MUCH FARTHER TO THE WEST ACROSS CENTRAL KS INTO SOUTHEAST NE RATHER THAN SOUTHERN MO...AS WITH FRIDAY/S STORM. THIS MAY INDICATE THAT A LOT OF THE DYNAMICA WILL BE NORTH OF THE AREA AND ONLY A SQUALL LINE WITH THE FRONT OR PRE-FRONTAL TROUGH CAN BE EXPECTED. (49) .LIT...NONE ar EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 345 AM PST SAT FEB 19 2000 OFFSHORE FLOW WILL CONTINUE ACROSS SOUTHWEST CALIFORNIA MOST OF TODAY. WIND ADVISORIES ARE IN EFFECT UNTIL MID MORNING. LOW LEVEL MOISTURE WILL INCREASE TONIGHT AS THE FLOW BECOMES SOUTHERLY. AN STORM APPROACHING FROM THE SOUTHWEST ON SUNDAY WILL SPREAD RAIN ACROSS MOST OF THE REGION. SNOW LEVELS WILL REMAIN ABOVE 7000 FEET UNTIL REINFORCING COLD AIR MOVES IN LATE SUNDAY AND MONDAY. LOW AND MID LEVEL OFFSHORE FLOW CONTINUES STRONG ACROSS SW CALIFORNIA THIS MORNING. PRESSURE GRADIENT ABOUT -10 MB BETWEEN SAN DIEGO AND ST. GEORGE UTAH BUT PROGGED TO DROP TO AROUND -6 MB BY 18Z PER RUC MODEL. BOUNDARY LAYER WINDS BECOMING MORE SE AS DAY WEARS ON. SO EARLIER FCST OF DROPPING WIND ADVISORIES/WARNING AT 17Z STILL SUPPORTED. HAVE DISCARDED ETA MODEL GUIDANCE WHICH APPEARS TO BE TOO FAST WITH MOVING LOW ONSHORE/MOISTENING LOW LAYERS. AVN MODEL PREFERRED THOUGH NGM VERY SIMILAR IN SOLUTION. SOUNDINGS BOTH OBSERVED AT 19/00Z AND PROGGED BY MODELS THROUGH 20/06Z KEEP AIR MASS BELOW 9000 FT DRY AND SHOW ABOUT 4-5 DEGREES FAHRENHEIT WARMING. DROPPED MENTION OF PCPN AND BUMPED TEMPERATURES UP TODAY...CLOSE TO FWC NUMBERS. MIST/DRIZZLE IS POSSIBLE ACROSS HIGHER SAN GABRIEL/SAN BERNARDINO MOUNTAINS DURING LATE AFTERNOON IF CLOUD BASE LOWERS FROM UPSLOPE AFFECTS AS MID LEVEL FLOW BECOMES MORE PERPENDICULAR TO RIDGE ORIENTATION. HEIGHTS/THICKNESSES DROP ABOUT 60 METERS TONIGHT/SUNDAY ALONG WITH RAPID MOISTENING IN THE LOW/MID LAYERS AS FLOW VEERS TO SW. EARLIER QPF GUIDANCE NUMBERS SHOWED NEAR 5 INCHES FOR COASTAL SLOPES. VERIFICATION WITH LAST EVENT SHOWED IT WAS ONLY A LITTLE ON THE HIGH SIDE. WILL TAKE A CLOSER LOOK AND LEAN MORE TOWARDS OROG/COMBINED NUMBERS VERSUS ORGG-NOGAP AS BASELINE. EARLIER COORDINATION CALL WITH ADJACENT OFFICES AGREED IT WAS TOO EARLY TO ISSUE WINTER STORM WATCH...BUT APPERAS TO BE SHAPING UP INTO THAT. SNOW LEVELS WILL DROP SIGNIFICANTLY SUNDAY NIGHT/MONDAY MORNING WHEN THE COLD AIR POCKET MOVES INLAND AND REINFORCING COLD AIR ADVECTION FROM THE NW ARRIVES...OPENING LOW UP INTO NEGATIVE TILT TROUGH. HEIGHTS/THICKNESSES DECREASE 100 METERS/24 HOURS BY 12Z MONDAY WHICH TRANSLATES INTO SNOW LEVEL DROPPING TO AROUND 4500 FEET. ALSO RISK OF TSTMS AS AIR MASS DESTABLIZES MON AFTN AS VALLEY FLOORS HEAT UP. IN THE MEDIUM RANGE...ALL THE US AND EUROPEAN MODELS WERE IN GOOD AGREEMENT. DIDN'T GET A CHANCE TO LOOK AT THE CANADIAN OR ENSEMBLE CHARTS TO SEE WHAT SUPPORT THEY GAVE TO OTHER GLOBAL MODELS SOLUTIONS OF LONG WAVE ADJUSTMENTS. FOR NOW IT IDEA OF REDEVELOPING TROUGH ALONG THE W COAST BY WEDNESDAY APPEARS VALID DUE TO PHASING OF THE NORTHERN BRANCH OF THE WESTERLIES WITH THE QUASI-PERMANENT TROPICAL UPPER TROPOSPHERIC TROUGH NEAR 125W. SO ONLY TEMPORARY AND DIRTY RIDGE FOR MON NIGHT/ TUE ACROSS SW CALIFORNIA. SAN 047 .SAN...WIND ADVISORIES CAZ048-049-058 UNTIL 900 AM PST HIGH WIND WARNING CAZ057 UNTIL 900 AM PST MINOR TIDAL OVERFLOW CAZ042-043-PZZ750 UNTIL 10 AM PST BALFOUR ca EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 927 AM EST SAT FEB 19 2000 CURRENTLY...LOW LEVEL RIDGE AXIS WELL DEFINED IN CLOUD FIELDS FROM STUART TO OKEECHOBEE. EXTENSIVE STRATUS WAS ADVECTING EASTWARD OVER NORTH FLORIDA AND EXTREME NORTHERN SECTIONS. MORNING SOUNDINGS SHOW MOISTURE HAS INCREASED TO A LITTLE OVER AN INCH. THIS IS SUFFICIENT TO ALLOW A NARROW BAND OF SCATTERED SHOWERS TO FORM OVER THE ATLANTIC IN CONFLUENT ZONE NORTH OF RIDGE AXIS. FORECAST...CUMULUS SHOULD SHOW MORE VERTICAL GROWTH THIS AFTERNOON WITH THE DEEPER MOIST LAYER AND WEAKENED CAP. THE LACK OF MUCH LARGE SCALE CONVERGENCE SHOULD KEEP ANY CHANCE OF SHOWERS TO LESS THAN 10 PERCENT. NOT PLANNING ANY CHANGES. MARINE...SURFACE ANALYSIS SHOWS THAT TIGHTENING OF GRADIENT IS MOST EVIDENT NORTH OF OUR WATERS. RUC/MESO ETA MODELS KEEP RIDGE OVER SOUTHERN SECTIONS THIS AFTERNOON WITH INCREASED GRADIENT REMAINING TO OUR NORTH. LATEST BUOY WINDS/SEAS WERE AT THE LOW END OF THE CURRENT FORECAST SO PROBABLY WILL LOWER SEAS OVER THE NORTHERN LEG. .MLB...NONE. LASCODY fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1040 AM CST SAT FEB 19 2000 BACK EDGE OF EARLY MORNING ST/FLURRIES HAS PUSHED INTO SECOND TIER OF WI CWA ZONES...JUST WEST OF RPD..EAU LN. WL UPDATE THIS AREA SHORTLY. WDL WIND PROFILER /UA ANALYSIS SHOWED 5H TROUGH LN HAS SHIFTED EWD THRU WRN CWA EARLY THIS MORNING BUT LOW LEVEL TROUGH HANGING BACK. SFC CLD FNT BEGINNING TO PUSH THRU RED RVR VLY TO JUST WEST OF ABR. MINIMAL CLDS POST FRONTAL BUT SOME LOW LVL MOISTURE THAT SHOWED UP ON 12Z ABR SOUNDING IS INTERACTING WITH WK LOW LVL CONV TO PRODUCE SECOND ST DECK ALG WITH SOME FLURRIES WHICH IS BEGNG TO SPREAD INTO NWRN CWA. LATEST RUC AND NEW ETA GUIDANCE CARRIES INCR LOW LEVEL RH/CONV THRU ABT NRN HALF OF AREA THRU AFTERNOON WITH DECR TREND IN WEST THIS AFTN AND EAST THIS EVE. WL UPDATE ZONES TO REFLECT MORE CLDS FOR A TIME IN NORTH ALG WITH FLURRY POTENTIAL. MORE SUN IN SOUTH. AFTN TEMPS IN BALLPARK WITH MINIMAL REVISIONS NEEDED. .MSP...NONE KAVINSKY mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 945 AM EST SAT FEB 19 2000 VISIBLE IMAGERY SHOWS LOW CLOUDS VERY SLOW TO ERODE THIS MORNING E OF THE HIGHER TERRAIN. SOME PROGRESS IS NOTED AROUND THE EDGES OF THE DECAYED WEDGE LAYER. MAY HAVE TO RETAIN SOME BECOMING PARTLY CLOUDY WORDING INTO THE AFTERNOON. WILL ASSESS UP TO ISSUANCE TIME. SLOW PROGRESS OF THE FRONT ACROSS THE FOOTHILLS AND PIEDMONT THIS AFTN WILL ALLOW TEMPS TO WARM ABOVE FWC NUMBERS...AS PRESENTLY FORECAST. MTN TEMPS WILL REACH HIGHS EARLY THIS AFTN AND THEN SLOWLY FALL WITH COLD ADVECTION AFTER 18Z. CURRENT TEMP RANGES LOOK VERY REASONABLE. WINDS REMAIN SOMETHING OF A CONCERN TODAY AS LATEST RUC AGREES WITH THE ETA IN BRINGING 20 TO 30 KT BOUNDARY LAYER FLOW ACROSS THE AREA. WITH WINDS GUSTING TO 17 KT AT GSP ALREADY THIS MORNING...MIXING SHOULD TAKE THE ENTIRE AREA TO LAKE WIND ADVISORY LEVELS. .GSP...WIND ADVISORY FOR AREA LAKES TODAY ALL ZONES. HG sc DEEP SOUTH TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 320 AM CST SAT FEB 19 2000 A PACIFIC COLD FRONT OVER SOUTHERN TEXAS WILL RAPIDLY MOVE SOUTH AND SHOULD MAKE IT TO THE VALLEY BY MID MORNING. THIS IN COMBINATION WITH A S/WV 500 MB TROUGH WILL MOVE THROUGH THE AREA TODAY. THE BRO SOUNDING LAST NIGHT INDICATED A PRECIP WATER OF 1.00 AND A LIFTED INDEX OF A MINUS 3.2. THE RUC AND THE NGM INDCT A SLIGHT CHANCE FOR SHOWERS AHEAD AND ALONG THE FRONT TODAY. WINDS WILL INCREASE FROM THE NORTHEAST IN THE WAKE OF THE FRONT TODAY CAUSING POSSIBLE SMALL CRAFT ADVISORIES FOR THE COASTAL WATERS. THERE IS A 10 MB DIFFERENCE BETWEEN SLC AND BRO WHICH WILL MAKE A FAIRLY STRONG FRONT WHEN IT GOES THROUGH TOWARD SUNRISE. TEMPERATURES WILL DECREASE CONSIDERABLY IN THE WAKE OF THE FRONT TO AN AVERAGE DROP OF ABOUT 15 DEGREES F. THE 500 MB FLOW BEHIND THE FRONT TODAY WILL BE WEST TO SOUTHWEST WHICH WOULD KEEP CLOUD COVER IN THE AREA THROUGH THE WEEKEND. AN INCREASE IN LOW LEVEL MOISTURE ON SUNDAY COULD CAUSE A SHOWER OR TWO. MARINE FORECAST...BOY020 HAS A WIND FROM THE SOUTHEAST AT 10 KNOTS WITH SEAS OF 5 FEET. WINDS AND SEAS SHOULD BOTH INCREASE IN THE WAKE OF THE FRONT CAUSING CONDITIONS TO BE ABOVE SMALL CRAFT ADVISORIES DURING THE DAY TODAY. WINDS SHOULD DECREASE TONIGHT AND ALSO ON SUNDAY. LONG TERM...A STRONG PACIFIC FRONT WILL MOVE THROUGH THE AREA THE END OF NEXT WEEK WHICH COULD CAUSE SOME SHOWERS OR THUNDERSTORMS. .BRO...SCA FOR GMZ130-150-155-170-175. 55 .BRO 71/56/75/58/78 10/00/10 .MFE 71/55/76/57/79 10/00/10 .RGD 71/52/78/55/81 10/00/10 .SPI 71/59/72/61/74 10/00/10 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1055 AM EST SAT FEB 19 2000 APX 88D DATA AND SURFACE OBSERVATIONS SHOW LIGHT SNOW SHOWERS AND FLURRIES AFFECTING NORTHWEST LOWER AND PARTS OF EAST UPPER MICHIGAN. THE EAST UPPER MICHIGAN AND STRAITS AREA SNOWFALL IS DUE TO A WEAK SURFACE TROUGH MOVING OVER UPPER MICHIGAN EXTENDING SOUTHWARD FROM AN AREA OF LOW PRESSURE NORTH OF LAKE SUPERIOR. NORTHWEST LOWER MICHIGAN SNOWFALL IS BEING ENHANCED BY OVER LAKE INSTABILITY ACROSS LAKE MICHIGAN WITH 850 TEMPERATURES AROUND -11C. THE AVERAGE WIND DIRECTION THIS AFTERNOON BETWEEN THE SURFACE AND 850 MB... WILL BE FROM THE WEST WITH 1000/850 MB MOISTURE CURRENTLY AROUND 70 PERCENT OVER THE NORTHERN GREAT LAKES. RUC MODEL SOUNDINGS SHOWING EAST UPPER MICHIGAN STAYING UNDER MOSTLY CLOUDY SKIES THIS AFTERNOON WITH LOWER LEVELS...BETWEEN THE SURFACE AND 850 MB...DRYING TO UNDER 60 PERCENT FOR THE WESTERN LAKES. THE LATEST VISIBLE STLT SHOWS BREAKS IN THE CLOUD COVER OVER EAST WISCONSIN AND LAKE MICHIGAN AS HIGH PRESSURE RIDGING CONTINUES TO MOVE INTO THE AREA. WILL MENTION SOME SUN AND FLURRIES FOR MUCH OF NORTHWEST LOWER THIS AFTERNOON. FOR EXTREME NORTHWEST LOWER AND STRAITS AREA WILL MENTION SCATTERED LIGHT SNOW SHOWERS AND FLURRIES AS LAKE ENHANCEMENT COMBINES WITH THE WEAK SURFACE TROUGH EXTENDING SOUTHWARD INTO THE STRAITS. .APX...NONE. SWR mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 258 AM EST SAT FEB 19 2000 DEFORMATION ZONE SN EXITING STAGE RIGHT...BRINGING THIS UGLY EPISODE TO A CLOSE. SHOULD BE ABLE TO ISSUE NEW ZFP WITHOUT ANY LINGERING -SN. A MORE BENIGN WX REGIME IS ON TAP FOR THE WEEKEND. ALTHOUGH CONFIDENCE IN THE MODELS IS NOT ESPECIALLY HIGH AT THE MOMENT...THEY ARE IN GOOD AGREEMENT. A WEAK CLIPPER-TYPE SHORTWAVE WL CROSS SE LOWER MI TONIGHT...OTHERWISE THINGS WL BE QUIET SYNOPTICALLY. DEEP MOISTURE IS GONE BY DAYBREAK...WITH ONLY A FEW TATTERS OF CIRRUS DURING THE DAY. THE BIG QUESTION IS LINGERING LOW LEVEL MOISTURE...GIVEN PATCHY STRATOCU ACROSS LOWER MI...AND WIDESPREAD STRATUS TO OUR WEST. BOTH THE ETA AND THE NGM BUCK THEIR USUAL BIASES. THE ETA ERODES ALMOST ALL OF THE BOUNDARY LEVEL MOISTURE THIS MORNING... BEFORE SLOWLY RETURNING IT AHEAD OF THE CLIPPER. THE NGM ALLOWS MORE MOISTURE TO LINGER DURING THE DAY. LOCALLY RUN 6KM ETA LOCKS THE LOW CLOUDS IN ALL DAY...WHEREAS RUC ADVERTISES A SLOW DECREASE IN MOISTURE FROM NORTH TO SOUTH THIS MORNING. CONCEPTUAL MODEL SUGGESTS THAT A DRY NE LOW LEVEL FLOW EARLY THIS MORNING...VERY DRY AIR ABOVE THE BOUNDARY LAYER...AND SUN SHINING THRU BREAKS IN THE CLOUDS...WL BREAK UP MOST OF THE LOW CLOUDS DURING THE MORNING. BUT FRESH SNOW COVER MAKES THIS A BIT TRICKY. AS LOW LEVEL FLOW BECOMES WEST BY MIDDAY... HIGHER BASED STRATOCU COULD MOVE IN WITHOUT MIXING OUT. WL GO A LITTLE MORE PESSIMISTIC WITH CLOUD TRENDS TODAY. WL ALSO SHADE UNDER GUIDANCE TEMPS GIVEN OUR NEW SNOW. MOISTURE WITH THE SHORTWAVE DROPPING DOWN TONIGHT IS LIMITED TO THE FAR NORTHERN ZONES. WITH VIRTUALLY NIL 1000-850MB CONVERGENCE PROGGED AS THE COLD FRONT SWEEPS THRU OVERNIGHT...DIFFICULT TO SEE MORE THAN A FLURRY SAGINAW BAY/UPPER THUMB. THANKS FOR COORD APX. ETA GENERATES SOME NW FLOW LAKE EFFECT PRECIP WITH AND BEHIND THE BOUNDARY. THE ETA IS ABOUT 4C COLDER AT 850MB THAN THE OTHER MODELS. CLOSE LOOK AT INITIALIZATION NORTHERN PLAINS/CENTRAL CANADA SUGGESTS THE TRUTH LIES BETWEEN THE COLD ETA AND WARMER NGM. THIS SUPPORTS SCT/OCNL BKN CLOUDS BEHIND THE FRONT LATE TONIGHT AND SUNDAY...BUT NO -SHSN FOR SE LOWER MI. WITH NGM LIKELY TOO WARM...WL GO UNDER FWC TEMPS SUNDAY...PRETTY CLOSE TO THE FAN. IN THE EXTENDED...WITH RIDGE AXIS BUILDING IN...MAKES SENSE TO LOWER TEMPS FOR SUNDAY NIGHT. OTHERWISE NO CHANGES. .DTX...NONE. ZOLTOWSKI mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 150 PM CST FRI FEB 18 2000 SHORT TERM FCST CONCERNS: FOG DEVELOPMENT TONIGHT...PCP SUN NITE/MON AVN/ETA/RUC BEST H5 INIT OF DIFF FEATURES. CLRG OF LOW CLDS WL BE CONICIDENT WITH PSG OF H5 VORT CTR. SOME BRKS EVIDENT IN NW CORNER OF CWA ATTM. CLDS MAY STAY ACRS ERN ZONES THRU EVENING HR WHICH...WL AFFECT TEMPS. ENUF RESID MOISTURE ARND TO ALLOW RAD FOG TO DEVELOP TONIGHT. RUC AND MM5 SHOW WNDS DECRSG BLO 7KT THRESHOLD BY 03Z WHEREAS...ETA/AVN/NGM KEEP WIND THRU 12Z. WL SPLIT THE DIFF AND MENTION LATE EVE FOG DEVELOPMENT. DENSER FOG ACRS WRN ZONES WHERE SKIES WL BE MSTLY CLR...ONLY LGT FOG FOR THE EAST. DONT XPCT TO SEE MUCH IN THE WAY OF FOG FORMATION ACRS WRN ZONES MON NITE DUE TO INCRSD WND SPDS. ERN ZONES MAY SEE A LTL FOG MON NITE AS WNDS WL BE A LTL LIGHTER AND CLDS WL BE SLOWER TO REACH THIS AREA. HOWLING 45-50KT LLJ BRINGS A SLUG OF LO LVL MOISTURE TO CWA WRN DOOR BY 06Z MON ACCORDING TO ETA. NGM AND AVN AND 00Z MM5 A LTL SLOWER WITH MOISTURE RETURN AND STRENGTH OF LLJ. ALL SHORT TERM MODELS QN AND QS FIELDS SHOWING WK CONV BY 12Z MON LIKELY DUE TO STG ISN LIFT AND MID LVL DIFF/DIV. NO POPS GOING IN CURRENT FCST FOR SUN NITE OR MONDAY. WL WAIT FOR THE LASTEST RUNS OF MESO MODELS B4 ENTERING PCP INTO FCST. WNDS MAY KEEP TEMPS FROM FALLING OFF TOO QUICKLY TONIGHT. CURRENT FCST MINS FOR TONIGHT LK GOOD. LO LVL WAA SHULD ALLOW ALL AREAS TO WARM NICELY TMRW. ANY FOG THAT DOES FORM OVR WRN ZONES OVERNIGHT LIKELY WL BURN OFF WITH PSG OF H8 RDG AXIS. MAY GO A LTL CLOSER TO COOLER FWC NUMBER TO ACCT FOR REDUCTION IN HTG DUE FOG. IF ETA IS BLVD...WARMER FAN NUMBERS FOR MON NITE LK GOOD. BREEZY AND WARM ON TUES... EXTENDED CONCERNS: TIMING OF -SHRA/-TSRA ONSET ALL LNG RNG MODELS POINTING TWD SOME SIG WX FOR CWA TUES NITE AND WED. ITS BEEN AN OKLA WINTER...CULD BE AN OKLA SPRING! SFC LOW FCST TO DEVELOP OVR WRN KS TUE NITE AND MV TO ARND ICT BY 12Z WED. MRF SFC LO PSN IN NC KS 12Z WED LKS A LTL ODD GIVEN H5 LO PROGGD TO BE OVR SC KS... UKMET AND EUROPEAN PSNS AT SFC AND H5 LK A LTL MORE REASONABLE. IF THEIR SCENARIO VERIFIES... LO LVL HELICITY WL ABOUND. HOWEVER...LAYER Q-VECTOR FIELDS AND ECMWF THERMAL WND FIELDS BOTH SUGGEST BEST LIFT AND MOISTURE WL BE NORTH AND WEST OF CWA ACRS SRN NE EARLY ON. PBLY WL SEE TWO AREAS OF STORMS...ONE ALNG AND NORTH OF WARM FNT ACRS SRN NE AND SRN IA AND THE OTHER ALNG INSTABILITY AXIS ORIENTED UNDER DRY SLOT ACRS WRN MO. WED AFTN AND EVE CULD BE FAIRLY INTERESTING. THE WHOLE SYSTEM MVS EAST OF FA BY 12Z THU... THU LKS DRY ACRS ENTIRE CWA. NCEP ENSEMBLES HAVE ANOTHER WK SYSTEM MVG THRU ON FRI. IN BTWN SYSTEMS ON SAT. .EAX...NONE SMF mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1007 AM CST SAT FEB 19 2000 MORNING KSGF SOUNDING INDICATED A SHALLOW LAYER OF HIGH RH... MAINLY BELOW 3300 FT. VIS SATELLITE CONTINUES THE LOW STATUS DECK OVR E KS... WITH A SLOW EROSION FROM WEST TO EAST. SOME BRIGHTENING IN VIS PICTURE AS INDICATED WITH SOME OF THE LOW CLDS FROM AIZ TO CNU. WILL WAIT UNTIL 1045 AM TO SEE IF CLDS WILL ERODE BY AFTN. MY FIRST INDICATION IS TO DECREASE CLD CVR OVR SE KS/ SW MO BY 19Z... WITH A TREND TOWARD PARTIAL SUNSHINE FROM AIZ TO SGF TO BRANSON... THEN SOME BREAKS IN OVERCAST FROM VIH TO UNO BY 21Z. THE CURRENT RUC STILL HAS 80-95% RH FROM 90H AND BELOW FROM VIH TO UNO AND ON EAST. WILL UPDATE ZONES BY 1045 AM. NO OTHER CHANGES ATTM. JLT mo