AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSONVILLE FL 1200 PM EST FRI DEC 17 1999 ZONES..WILL HOLD OFF ON ANY AMDS. THE TEMPS OVER N FLA SEEM TO HAVE RESPONDED WELL TO THE EARLIER THINNING OF THE CI/CS CANOPY AND ARE NOW CLOSE TO FWC GUIDANCE. ALSO BASED ON SAT IMAGERY...THE CI/CS OVER GA LOOKS TO BE THIN ENOUGH THAT CURRENT WORDING IS ACCEPTABLE. THEREFORE WILL NOT AMD THE CURRENT ZONE PACKAGE. MARINE...WINDS AT ST. AUGUSTINE PIER HAVE BEEN STEADY AT 20 KNOTS PAST TWO HOURS AND WE HAVE A MARINE REPORT...FROM SEA LOVERS MARINA IN ST. AUGUSTINE...THAT INDICATES THAT THE WINDS 16 NM OFFSHORE ARE E TO NE AT 17 KNOTS...SEAS OF 3-5 FEET. THEREFORE...HAVE INCREASED THE WINDS TO 15 TO 20 KNOTS FOR THE FLORIDA WATERS AND SINCE THIS MEETS SCEC CRITERIA AN SCEC HAS BEEN ISSUED. ADDITIONALLY...AS THE REGION IS AT THE END OF THE FETCH AREA AND RUC INDICATES THE WINDS WILL STAY UP INTO THE EVENING HOURS HAVE INCREASED SEAS BUILDING TO 4 TO 6 FEET. .JAX... GA...FIRE WX WATCH GAZ150-164 THRU SS. FL...FIRE WX WATCH FLZ020>023-030-035 THRU SS. SANDRIK fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 950 AM EST FRI DEC 17 1999 ZONES..CI/CS CANOPY HANGING IN THERE...INCLUDING SERN GA. WE'VE GOT A LITTLE SUCKER HOLE OVER JACKSONVILLE RIGHT NOW...BUT LOOKING AT THE VSBL IMAGERY THE CLOUDINESS IS SOLID ALL THE WAY INTO GULF. THINK I WILL AMD THE ZONES AND GO "OVERCAST" FOR ALL ZONES THIS AFTERNOON. ALSO THINKING ABOUT LOWERING THE TEMPS A CAT FOR ALL ZONES AS WE'RE RUNNING AROUND 5 DEGREES BELOW GUIDANCE AT THIS POINT. WILL TAKE OUT THE MENTION OF A "COASTAL SHOWER" AS THEY ARE NOT FORMING OVER THE COASTAL WATERS ATTM AND DON'T REALLY EXPECT SHOWER DEVELOPMENT OVER THE COASTAL WATERS THIS AFTERNOON. EVEN IF DEVELOPMENT DID OCCUR THE LLVL AMS IS SO DRY I DOUBT THEY COULD GET TOO FAR INLAND ANYWAY. WILL NOT AMD ZONES UNTIL ABOUT 11 AM AND WILL WATCH TEMPERATURE TRENDS CLOSELY BEFORE PULLING THE TRIGGER. MARINE...WINDS AT ST. AUGUSTINE PIER HAVE BEEN AOA 15 KNOTS SINCE 6 AM...AND GRAYS REEF DONE LIKEWISE SINCE 7 AM. NGM SEEMS TO BE DOING THE BEST JOB WRT MARINE WINDS THIS MORNING. LOOKING AT THE RUC WINDS SHOULD STAY AOA 15 KNOTS ALL DAY. DON'T WANT TO RECOMBINE THE MARINE ZONES DUE TO DIFFERENCES IN THE LATER PORTIONS BUT GO WITH N-NE WINDS AT 15 KNOTS...SEAS 3 TO 5 FEET IN ALL AREAS FOR THIS AFTERNOON. I DON'T WANT TO YO-YO THE NE FLA WATERS FORECAST AND WILL LEAVE AT 15 KNOTS FOR NOW...BUT WILL UPDATE IF TRENDS INDICATE A CONTINUED 15 TO 20 KNOT ERLY FLOW THIS AFTERNOON. THANKS FOR THE COORD KCHS. .JAX... GA...FIRE WX WATCH GAZ150-164 THRU SS. FL...FIRE WX WATCH FLZ020>023-030-035 THRU SS. SANDRIK fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 900 PM EST FRI DEC 17 1999 SYNOPSIS: A WEAK TROUGH OF LOW PRESSURE WILL MOVE THROUGH THE REGION OVERNIGHT. THEN LOOK FOR AN ARCTIC HIGH PRESSURE SYSTEM TO APPROACH FROM THE GREAT LAKES IN ITS WAKE DURING SATURDAY AND BECOME CENTERED OVER NORTHERN NEW ENGLAND SATURDAY NIGHT AND SUNDAY. THIS WILL RESULT IN SOME OF THE COLDEST AIR TO COVER THE REGION SO FAR THIS SEASON OVER THE WEEKEND. TECHNICAL DISCUSSION: IR/WV IMAGERY LOOP INDICATING SHORT WAVE CURRENTLY MOVING THROUGH SOUTHERN QUEBEC PROV TO TRACK ACROSS NORTHERN MAINE OVERNIGHT MUCH IN LINE WITH LATEST RUC AND 12Z MODEL FORECAST. BEST ENHANCEMENT MOVING ACROSS THE ST. LAWRENCE VALLEY MAY CLIP EXTREME NORTHERN AREAS OTHERWISE PATCHES OF CLOUDS TO MOVE ACROSS REGION POSSIBLY PRODUCING SOME FLURRIES ACROSS THE NORTH. TEMPS DROPPING SLOWLY AS A RESULT OF CLOUD COVER AND WIND. PREVIOUS PACKAGE IN GREAT SHAPE SO ANY CHANGES WILL BE MINOR. COASTAL WATERS: WITH LOW LEVEL CAA CONTINUING TO ENHANCE MIXING IT APPEARS SCA'S LIKELY TO BE NEEDED FOR MUCH OF THE OVERNIGHT PERIOD. CAR BU 012/020 005/023 010 06110 222/221/00/N BGR UU 018/028 012/030 020 06100 222/221/00/N .CAR...SCA. FITZSIMMONS me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 928 PM EST FRI DEC 17 1999 DISC: WATCHING A LARGE PATCH OF AC MARCHING ACROSS PA AND INTO HUDSON VALLEY/NJ IN ASSOCIATION WITH SLOW MOVING TROF AND BROAD/WEAK SFC LOW. CLOUDS APPEAR TO BE A BIT FARTHER NORTH THAN PRVS MODEL RUNS INDICATED...BUT EVEN NEW RUC MODEL SHOWS THE NORTHERN EDGE HAVING DIFFICULTY REMAINING ANY FARTHER NORTH THAN THE MASS TURNPIKE AS IT SLIDES EAST. XPCT THAT THE DRY AIR WILL CONTINUE TO ERODE NE EDGE OF CLOUDS AS THEY HEAD EAST. NONETHELESS...CT/RI/S COASTAL MA ARE THE MOST VULNERABLE TO THE CLOUDINESS LATER OVERNIGHT AND WILL GO WITH GO WITH A BCMG MOCLOUDY FCST SOUTH AND PCLDY NORTH. ALTITTLE BIT OF SNOW OCCURRING IN OHIO/PA...BUT WITH CONSIDERABLY DRY AIR IN PLACE... DON/T EXPECT ANY PCPN TO REACH THE GROUND. WINDS WILL EVENTUALLY BECOME MORE NW OVERNIGHT AS THE COLD AIR SINKS DOWN INTO THE CWA. MINOR ADJ NECESSARY TO TEMPS AND WINDS. MARINE: MODERATE TO STRONG SMALL CRAFT WINDS PERSIST. THESE WINDS SHOULD BE AT THEIR PEAK BEFORE MIDNIGHT...THEN TAIL OFF SOMEWHAT. SCA WILL REMAIN POSTED FOR ALL COASTAL WATERS. .BOX...SCA ALL MARINE WATERS. DCY ma AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 935 PM EST FRI DEC 17 1999 THE LATEST APX 88D WIND DATA SHOWS WIND DIRECTIONS SHIFTING FROM THE NORTHWEST (330)... NOW MORE TOWARD THE NORTH (360)...AS A LARGE AREA OF HIGH PRESSURE MOVES INTO THE WESTERN GREAT LAKES. APX 88D SHOWING THE ONCE TYPICAL NORTHWEST FLOW BANDS NOW BEGINNING TO SHIFT NORTH AND AFFECT LOCATIONS AROUND TRAVERSE CITY...CADILLAC AND MANISTEE INSTEAD OF MANCELONA...GAYLORD AND KALKASKA. RUC MODEL SOUNDINGS FOR NORTHWEST LOWER MICHIGAN...MAINLY AROUND MBL AND TVC...SHOW INVERSION HEIGHTS TO 5000 FEET INTO THE OVERNIGHT HOURS... WITH MOISTURE UNDER THE INVERSION TO 80 PERCENT. 850 MB TEMPERATURES ARE FORECAST TO REMAIN AROUND -12C INTO THE OVERNIGHT HOURS. EXPECT LAKE EFFECT SNOW TO REMAIN OVER EXTREME NORTHWEST LOWER MICHIGAN INTO THE EARLY MORNING HOURS... BEFORE THE SURFACE RIDGE MOVES IN AND LOWERS THE INVERSION HEIGHTS AND DIMINISHES THE LAKE EFFECT SNOW. THEREFORE WILL CONTINUE LAKE EFFECT SNOW FOR TVC...MBL AND CAD INTO THE OVERNIGHT. FOR THE REST OF NORTHERN LOWER AND EAST UPPER MICHIGAN... WILL MENTION PARTLY CLOUDY SKIES OVERNIGHT WITH COLD TEMPERATURES INTO THE SINGLE DIGITS. WILL KEEP A MENTION OF FLURRIES FOR THE CENTRAL PORTIONS OF NORTHERN LOWER AND EAST UPPER DUE TO LINGERING LOW LEVEL MOISTURE AND SOME WEAK UPPER LEVEL CYCLONIC FLOW. .APX...NONE. SWR mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 410 PM EST FRI DEC 17 1999 12Z ROABS/WV LOOP SHOW RELATIVELY LO AMPLITUDE TROF IN E WITH RDG OUT W. A NUMBER OF SHRTWV TROFS/RDGS EMBEDDED IN THIS FLOW THAT MAY PLAY A ROLE IN THE WEATHER OVR UPR MI: SHRTWV RDG OVR WRN ONTARIO... A SHRTWV TROF OVR NCNTRL SASKATCHEWAN...AND A POTENT LOOKING SHRTWV NOW APRCHG THE PAC NW CST. AT THE SFC...LATEST MSLP PLOT SHOWS A LK INDUCED TROF LINGERING ACRS SRN LK SUP. COMBINATION OF ASSOCIATED LLVL CNVGC...H85 -18C THERMAL TROF OVR ECNTRL LK SUP AT 12Z...AND INVRN HGT NR 5-6K FT PER 12Z APX SDNG RESULTING IN MULTIPLE LES BANDS OVR MAINLY THE ERN LK PER 88D LOOP/SAT PIX. GREATEST INTENSITY OF SN E OF MQT WHERE LO LVL CNVGC A BIT TIGHTER...DOWNWIND OF H85 THERMAL TROF...AND GREATER FETCH LENGTH. SPOTTER RPRT FM PINE STUMP JCT IN LUCE COUNTY INDICATED 3" SN IN 11/2 HR PD ARND 13Z IN DOMINANT BAND IN CNVGC BTWN WNWLY LAND BREEZE S OF SFC TROF AND MORE NLY FLOW TO N OF TROF. BUT REFLECTIVITY TRENDS/LO LVL CNVGC STARTING TO DIMINISH (AS FCST BY EARLIER RUC MODELS AND EVIDENCED BY LESS CONFLUENT SFC WNDS) AS H85-5 QVECTOR DVGC/SUBSIDENCE AND RISING HGTS AHD OF ONTARIO SHRTWV RDG STARTING TO LWR INVRN HGT/RAISE H85 TEMPS AND WEAKEN SYNOPTIC SUPPORT FOR SFC CNVGC. JUST FLURRIES NOW OVR WRN ZNS WITH BANDS THERE GREATLY DIMINISHED. BAND OF HI CLD CROSSING CWA WITH BACK EDGE OVR WRN LK SUP. SHALLOW COLD AIRMASS HI PRES PRESENT TO N OF LK SUP WITH 12Z YPL SDNG SHOWING NR SFC BASED INVRN. A BAND OF LGT SN NOTED IN WAD PATTERN ON BACK SIDE OF THIS SFC HI AHD OF SASKATCHEWAN SHRTWV... BUT PCPN INTENSITY LIMITED BY DRY ATMOSPHERE WITH NWLY FLOW ALF COMPLETELY CUTTING OFF MSTR INFLOW. MAIN FCST CONCERNS FOR TNGT PD ARE LES/CLD TRENDS AND TEMPS. GIVEN RADAR TRENDS...RECENT DIMINISHING TREND OF BANDS NR CAN SHORE AND CONTD NEGATIVE UPR DYNAMICS DIMINISHING LO LVL CNVGC...WL LET LES ADVY FOR ERN ZNS EXPIRE. SINCE ETA/RUC SHOW LGT NLY FLOW PERSISTING INTO EVNG AND DELTA-TS REMAINING IN 17-20C RANGE...WL CONTINUE AT LEAST SCT -SHSN NR LKSHORE E OF MQT THIS EVNG. BUT LO INVRN HGT WL LIMIT ANY ACCUM TO 1 INCH OR LESS EVEN IN FVRD AREAS OF WRN ALGER COUNTY. WITH CLRG TREND OVRNGT AS FLOW BCMS MORE ACYC...XPCT MIN TEMPS IN BEST RADIATION SPOTS TO DROP BLO MOS FCST. LK MODERATION/ CLRG WL BE GREATEST/SLOWEST OVR ERN ZNS...SO TEMPS AOA MOS THERE. MODELS SHOW SASKATCHEWAN SHRTWV TRACKING E WELL TO OUR N TMRW. SINCE AIRMASS QUITE DRY AND BEST H85-5 QVECTOR CNVGC FCST TO REMAIN WELL TO N...WL LEAVE OUT MENTION OF PCPN AND HIT CLDS HARDEST OVR NRN TIER. INCRSG SWLY FLOW AS SFC HI SHIFTS TO E MAY RESULT IN SOME SCT -SHSN OVR SCHOOLCRAFT COUNTY...WITH H85-LK DELTA-T PROGGED NR 15C AND INVRN HGT 3K FEET. XPCT HI TEMPS CLOSER TO LWR FAN NUMBERS PER UPSTREAM TEMPS TDAY. MODELS REDVLP LO PRES IN NRN PLAINS ON SUN AHD OF SHRTW NOW ARPCHG PAC NW. SHORT TERM AND XTNDED MODELS IN RSNBL AGREEMENT ON TIMING OF THIS SYS AND INDICATE SFC LO PRES TO MOVE ENEWD INTO ONTARIO SUN-MON. FCST SFC-H85 RDG ACRS SCNTRL STATES WL CUTOFF SYS FM APPRECIABLE GLFMEX MSTR...SO LOOKS LIKE LTL IN THE WAY OF OVRRNG SN AHD OF SYS WITH FCST ISENTROPIC LIFT ALSO LIMITED. MODELS SHOW INCRSG SWLY GRADIENT FLOW AHD OF THIS SYS WITH ETA/AVN INDICATING H85 SWLY WND TO 50/45 KTS BY F48 OVR WRN LK SUP. ETA OFTEN OVRFCSTS STRENGTH OF LLJ. BUT WL ADD BRISK TO FCST SAT NGT AND WINDY ON SUN AS SHARPEST PRES GRADIENT OVHD THEN. ALTHOUGH SKIES WL CLR BEHIND CAN SHRTWV SAT NGT (XCPT OVR SCHOOLCRAFT COUNTY WITH SWLY FLOW OFF LK MI)...STEADY WND WL KEEP TEMPS FM PLUMMETING. WL GO WITH INCRSG CLD ON SUN...BUT UNDERCUT FWC POPS GIVEN WEAK ISENTROPIC LIFT AND DRY MID LVLS. ALTHOUGH XTNDED MODELS AGREE ON SPEED OF NXT SHRTWV...CONSIDERABLE DISAGREEMENT ON DEGREE OF SPLITTING OF SHRTWV AND RESULTANT STRENGTH OF LO PRES PASSING TO N. OPERATIONAL MRF OUTLIER IN DEPICTING MORE SPLITTING OF SHRTWV WITH STRGR SRN SYS AND GREATER FALL OF PRES TO S AT EXPENSE OF NRN LO PRES. MRF ACTUALLY DVLPS FAIRLY INTENSE LO TO S AND RIDES SYS N ON COLD FNT TRAILING S FM ONTARIO LO. OTHER MODELS GENERALLY SHOW DEEPER CANADIAN LO PRES WITH LTL IF ANY DVLPMNT TO S. MEAN MRF ENSEMBLE STRONGER THAN OPERATIONAL MRF ON STRENGTH OF LO PRES IN CAN AND WEAKER ON TROFFING ASSOCIATED WITH SRN BRANCH SHRTWV. ENSEMBLE MEAN MORE IN LINE WITH OTHER MODELS AND WOULD BE A MORE RSNBL SOLN GIVEN EARLIER NCEP DISCUSSION (PMDHMD) SUGING 00Z MODELS UNDER ANLYZD STRG OF SYS MOVG INTO PAC NW (WHICH WOULD FAVOR ONE STRG LO). SINCE 12Z AVN HAS TRENDED AWAY FM 00Z MRF SOLN AS WELL (TOWARD A DEEPER CANADIAN LO WITH HIER PRES TO S) AND 12Z NCEP DISCUSSION FAVORS STRGR NRN LO...WL DISCOUNT OPERATIONAL MRF SOLN AND GO WITH JUST MORE OF AN LES SCENARIO MON/TUE VS SYNOPTIC SN AS STRG NWLY FLOW ADVECTS COLD AIR OVR LK SUP. MODELS IN VERY GOOD AGREEMENT SHOWING A HI AMPLITUDE WRN RDG/ERN TROF DVLPG EARLY NXT WEEK. SUCH AN UPR FLOW WOULD SUG FAST MOVG CLIPPER TYPE SYS WITH BLO NORMAL TEMPS AND FREQUENT EPISODES OF LES. COORDINATED WITH APX. .MQT...NONE. KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1215 PM EST FRI DEC 17 1999 LIGHT SNOW HAS MADE ITS WAY AS FAR AS LENAWEE COUNTY BY LATE MORNING. STILL EXPECT SOME SNOW TO MAKE IT INTO MONROE COUNTY...AND POSSIBLY WAYNE AND WASHTENAW COUNTIES. RUC SHOWS BEST MOISTURE BETWEEN NOW AND ABOUT 21Z WITH SHARP GRADIENT ACROSS FAR SOUTHERN CWA. SNOW HAVING A HARD TIME PUSHING NORTH...WITH JXN...RMY...AND ARB YET TO SEE A FLAKE. WITH SURFACE OBS AND MODEL GUIDANCE SUGGESTING PUSH TO THE NORTH TO BE LIMITED THIS AFTERNOON WILL KEEP 60 PERCENT POPS FOR LENAWEE COUNTY...PUSH MONROE COUNTY BACK TO 50 PERCENT...AND PUSH POPS BACK TO 30 PERCENT FOR WASHTENAW AND WAYNE COUNTIES. SKY COVER SOMEWHAT PROBLEMATIC...WITH HIGH CLOUDS ACROSS NORTH...MID CLOUDS TO THE SOUTH...AND THE OCCASIONAL LOW CLOUD ACROSS FAR SOUTH. WILL GO WITH PARTLY SUNNY ACROSS NORTHERN CWA...AND MOSTLY CLOUDY ELSEWHERE. WILL TINKER SOME WITH WINDS...BUT SPEEDS SUFFICIENTLY LIGHT TO BE OF NO REAL CONSEQUENCE. .DTX...NONE. OKEEFE mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 935 AM EST FRI DEC 17 1999 88D AND SURFACE REPORTS INDICATE FLURRIES HAVE DISSIPATED ACROSS THE REGION. HENCE WILL REMOVE MENTION OF FLURRIES FROM FNT/PTK ZONE. 06Z RUN OF ETA SHOWS DEEPEST MOISTURE ASSOCIATED WITH CLIPPER SYSTEM RIGHT NOW...WITH MOISTURE TO DIMINISH THROUGH THE DAY AS CLIPPER SLIDES SOUTH OF CWA. RUC NOT QUITE AS AGGRESSIVE IN DRYING SYSTEM OUT AS IT APPROACHES. LIGHT SNOW NOW AT DFI. RUC MOISTURE PROFILE SUGGESTS SNOW POSSIBLE INTO AT LEAST LENAWEE COUNTY BEFORE NOON...AND POSSIBLY MONROE AS WELL. SO WILL UPDATE THOSE COUNTIES TO LIGHT SNOW LIKELY BY NOON...AND CONTINUING THROUGH AFTERNOON. QPFS ON ORDER OF A FEW HUNDRETHS...SO WILL BE HARD PRESSED TO EKE AN INCH OUT OF THE SNOWFALL. .DTX...NONE. OKEEFE mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1030 AM CST FRI DEC 17 1999 MID LEVEL CLOUDINESS PERSISTING OVER AREA. LATEST RUC MODEL SUPPORTS THIS MOISTURE UNTIL LATE AFTERNOON. ZONES HAVE BEEN ADJUSTED TO REFLECT THIS WITH MORE CLOUDINESS IN ERN AREAS. HIGH TEMPERATURES HAVE BEEN RAISED SLIGHTLY IN SRN AREAS WITH HIGHER EARLY MORNING TEMPERATURES. .MSP...NONE. SCOTT mn SOUTH CENTRAL NEBRASKA/NORTH CENTRAL KANSAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 1140 AM CST FRI DEC 17 1999 LIGHT RAIN CONTINUES ON NORTH CENTRAL KANSAS WITH FAVORABLE COUPLED JET STRUCTURE AND ASSOCIATED H3 DIVEREGENCE AS SEEN ON THE RUC. NO SNOW REPORTED YET WITH MOST TEMPERATURES LIKELY IN THE 34 TO 38 DEGREES. HOWEVER...COLDER AIR STILL SLIPPING INTO NORTHERN SIDE OF RAIN SHIELD WARRANTS AT LEAST THE POSSIBILITY OF A MIX AT TIMES. CORCORIA HAS SLIPPED TO 30 DEGREES THE PAST HOUR. THE RAIN SHOULD TAPER OFF QUICKLY AFTER 3:00 PM. IN NEBRASKA...HAVE SIGNIFICANTLY LOWERED TEMPERATURES IN MOST OF THE 24 COUNTIES DESPITE WARMER AIR IN THE KLNX/KGLD CWFAS. NORTHEAST ZONES HAVE GONE NOWHERE AND SEE NO REASON FOR THEM TO WITH CLOUDS...NORTHEAST WINDS AND CONTINUED PRESSURE SURGE REINFORCING THE COLD AIR. UPPER 20S FORECASTED THERE WITH JUST SLIGHTLY WARMER THROUGH THE TRI-CITIES AREA. WE ARE A STEADY 23 DEGREES HERE. FAR SOUTHWEST COUNTIES NEAR McCOOK ARE PROBABLY THE ONLY AREAS TO REALLY HAVE DECENT CHANCE AT STAYING THE 30S...BUT EVEN LXN AND HDE HAVE FALLEN TO NEAR 30 RECENTLY. A FEW FLURRIES UPSTREAM ON KLNX/KUNR RADARS APPEAR HEADED OUR WAY TOO. .GID...NONE. MORITZ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 925 PM EST FRI DEC 17 1999 MID LYR OF FAIRLY LARGE GEOGRAPHICAL EXTENT MOVG NE FM ABT KSYR-KMGJ AXIS WITH WRMFNT TAKING SHAPE INVOF MASON DIXON LN. RUC PLACES MSTR GRAD FM THIS NWD TO JUST SHY OF KALB BY ARND 03Z...WL INTRODUCE MORE CLDS INTO SRN ZONES AND BRK WRN ULSTER CO OUT FOR LOW GRADE CHC OF LGT SN AND WL BUMP TEMPS SLGTLY. SOME ADDITIONAL DIRECTIONAL SHEAR KEEPING FLRYS FM DLVPG INTO ANYTHING OF SUBSTANCE ACRS SRN ADRNDCKS...WL ADD SOME DETAIL TO MAKE SRN PTNS OF ADRNDCK COS MORE CLD PRONE THAN NRN BDR SXNS. MCKINLEY/MAC .ALB...NY ERN/VT EXTRM SRN/MA EXTRM WRN/CT NW...NONE. ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 815 PM EST FRI DEC 17 1999 SATELLITE SHOWING EXTENSIVE CIRRUS SHIELD STREAMING NORTH FROM THE GULF OF MEXICO. RUC-II PICKS UP THIS TREND RATHER WELL AND WILL WORD OVERNIGHT FCST AS CONSIDERABLE HIGH CLOUDINESS. THE CLOUDS DO NOT SEEM TO HAVE MUCH AFFECT ON TEMPS SO FAR AS MHX ALREADY DOWN TO 39. WITH DEWPOINTS IN THE MIDDLE 30S...CURRENT FCST MINS ON THE MAINLAND LOOK FINE...BUT WILL NEED TO LOWER OUTER BANKS AS HAT/MQI ALREADY BLO FCST VALUES. COASTAL...WITH AXIS OF SURFACE HIGH OVERHEAD...WINDS VERY LIGHT AND VARIABLE. ONLY MINOR WORDING CHANGES TO CWF. .MHX...NONE. COLLINS nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 902 PM EST FRI DEC 17 1999 HIGH CLOUDS CONTINUE TO STREAM ACROSS THE CWA AND EXPECT MID DECK TO MAKE ADDITIONAL PROGRESS NE THROUGH THE NIGHT. DUE TO CLOUD COVER... EXPECT TEMPS TO BE MUCH WARMER THAN LAST NIGHT AND CURRENT FCST WITH A RANGE FROM NEAR 40 INLAND TO THE UPPER 40S AT THE COAST LOOKS REASONABLE. AS FAR AS PRECIP FOR COASTAL GA IS CONCERNED...THINK IT WILL BE A CLOSE CALL ON TIMING AND MAY TAKE UNTIL SAT FOR PRECIP TO BREAK OUT OVER THE CWA. CURRENT POPS ONLY CALL FOR 20 TO 30 SO WILL LEAVE THEM IN DUE TO UNCERTAINTY. RUC TRIES TO SHARPEN UP THE COASTAL TROF LATER TONIGHT FRTHR N WHICH COULD ACT TO INCREASE PRECIP CHANCES IN THIS AREA. TIGHTER PRESSURE GRADIENT OVER THE GEORGIA WATERS BETWEEN THE COAST AND THE TROUGH OFFSHORE HAVE RESULTED IN SOME STRONGER WINDS IN THIS AREA. LOOKS LIKE GRADIENT MAY TEMPORARILY RELAX FOR A WHILE OVERNIGHT BEFORE TIGHTENING UP AGAIN BY DAYBREAK. WILL PROBABLY JUST GO WITH A MEAN WIND SPEED OF 15 KNOTS THROUGH THE NIGHT. MEANWHILE FURTHER NORTH GRADIENT IS EXPECT TO REMAIN WEAKER RESULTING IN LIGHTER WINDS AND LOWER SEAS. MARINE FORECAST FOR THIS SECTION IS LOOKING OK. .CHS... SC...NONE. GA...NONE. SLF/ sc AREA FORECAST DISCUSSION FOR CENTRAL/NORTHCENTRAL AND NORTHEAST SOUTH DAKOTA AND WEST CENTRAL MINNESOTA NATIONAL WEATHER SERVICE ABERDEEN SD 1015 AM CST FRI DEC 17 1999 ONLY MINOR ADJUSTMENTS TO EARLY AM ZONE PACKAGE. WEAK SURFACE RIDGE POKING INTO NE SD EXTENDS SW TOWARD PIR. MOISTURE AS SHOWN IN RUC T-SECTS AND ETA...ALONG WITH AREA OBS...SUPPORT KEEPING VAST MAJORITY OF CWA CLOUDY WITH CHC OF A FEW FLURRIES...EVEN SOME FOG HANGING IN AROUND PIR AREA. WINDS CURRENTLY LIGHT...AROUND 5 KTS OR LESS...AND SHORT RANGE MODELS DO NOT INCREASE WINDS SIGNIFICANTLY TODAY...SO MAIN ADJUSTMENTS MADE THERE. DRIER AIR LOOKS TO BE MOVING IN TONIGHT...BUT BELIEVE ONLY OUR NW COUNTIES WILL SEE ANY SIGNIFICANT CHANCE OF CLEARING BEFORE SUNSET. .ABR...NONE. LORENS sd TEXAS/OKLAHOMA PANHANDLES FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE AMARILLO TX 957 PM CST FRI DEC 17 1999 IR IMAGERY LOOP SHOWING MID/UPPER LEVEL WAVE HAS SOUTHEAST OUT OF THE AREA AND HAS TAKEN THE COLDER/HIGHER CLOUD TOPS WITH IT. HOWEVER... FOG PRODUCT DEPICTING LOW CLOUDS AND FOG HAS NEARLY ENCOMPASSED ALL OF CWA. ANY PCPN FALLING FROM STRATUS DECK WILL BE VERY LIGHT AND ISOLATED IN NATURE...I.E. DRIZZLE OR FLURRIES. WITH BL BECOMING NEARLY SATURATED DUE TO RADIATIONAL COOLING AND LITTLE IF ANY CAA TAKING PLACE...TEMPS MAY NOT DROP AS LOW AS ORIGINALLY THOUGHT... PARTICULARY IN THE SRN AND ERN ZONES. A QUICK LOOK AT 00Z ETA/NGM AND LATEST RUC SUGGEST THAT WINDS SHOULD SLACK OFF FAIRLY QUICKLY TOWARDS DAYBREAK BEFORE SWITCHING AROUND TO SOUTH AND SOUTHWEST ON SAT. ALSO...DO NOT SEE ANY SUBSTANTIAL LIFTING MECHANISM NOR LOW/MID LEVEL MOISTURE TO CONTINUE WITH PCPN WORDING FOR TONIGHT/SAT. THEREFORE...WILL SHORTLY UPDATE ALL ZONES TO REFLECT THESE TRENDS. .AMA... TX...NONE. OK...NONE. JH tx SOUTHEAST TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 930 AM CST FRI DEC 17 1999 A MIX OF LOW...MID AND HIGH CLOUDS ACROSS SERN TX THIS MORNING. KHGX/KCRP SHOW ISOLATED TO WIDELY SCATTERED SHOWERS IN THE GULF JUST OFF THE COASTAL BEND. THE MAIN UPDATE ISSUES ARE COASTAL POPS AND AREAWIDE TEMPS. THE 12Z CRP/LCH SOUNDINGS AND GOES SOUNDER PRECIP WATER SHOW MOISTENING SINCE 12Z THU...ALTHOUGH NOT NEARLY AS MUCH AS THE 12/16 12Z ETA. VIS IMAGERY CONFIRMS CUMULUS/WEAK CONVECTIVE NATURE OF SHOWERS OFF THE COAST. THE 12Z RUC HAS TOO HIGH OF POP/QPF OVER THE GULF...BUT SEEMS TO BE ACCURATELY VERIFYING THE NORTHERN EDGE OF THE PRECIP. THIS NORTHERN EDGE SHOULD CONTINUE TO WORK NORTH THROUGH THE DAY AND END UP NEAR GALVESTON BY 00Z. WILL BUMP UP BOTH COASTAL WATER AND LAND ZONES TO LOWER SCT POPS. TEMPS LOOK ON TRACK...NO CHANGES. .HGX...NONE. PRELIMS... CLL BB 068/043 060/038 063 010 IAH BB 067/047 064/043 065 02- GLS BB 063/054 061/047 062 021 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 1110 AM CST FRI DEC 17 1999 LATEST RUC CONTINUES 500 MB CYCLONIC FLOW ACROSS THE FORECAST AREA INTO TONIGHT...WITH THE ETA 12Z RUN NOT BRINGING IN SOME RIDGING UNTIL AFTER 12Z ON SATURDAY. THE RUC RH FIELDS KEEP THE AREA SATURATED IN THE MID TO HIGH LEVELS. THE SURFACE HIGH...CURRENTLY AROUND THE ARROW-HEAD OF MN...IS HELPING SCOUR THE LOW CLOUD COVER. BEST CLEARING CHANCES DON/T REALLY WORK INTO THE AREA UNTIL THAT RIDGE APPROACHES. THIS SHOWS UP WELL IN CURRENT SATELITE IMAGERY. WILL KEEP THE AREA MOSTLY CLOUDY THEN...EXCEPT TO THE FAR NORTH WHICH WILL HAVE SOME BITS OR SUN AND/OR FILTERED SUNSHINE. TEMPERATURES WILL BE HARD TO MOVE WITH THE CLOUDS AND NORTHERLY FLOW. .LSE...NONE. RIECK wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 328 AM EST SAT DEC 18 1999 MAIN FCST PROBLEMS ARE TEMPS AND EXTENDED WITH FIRST SIG LES EVENT OF THE YEAR DY4. MODELS SIMILAR WITH STRNG ENERGY IN NWRN US. 150 KT JET DIGS THROUGH F48 WITH SIG FALLS ACRS CNTRL US INTO MEXICO AND RISES NR 135W. MODELS SIMILAR OVERALL BUT FEEL ETA UNDERPLAYS JET AND OLD MEX CYCLOGENSIS LT IN FCST PD AND TOO FAST WITH SFC FNT WHILE AVN WK WITH NRN STREAM ENERGY SO WL TREND TO A MODIFIED NGM SOLN EVEN THOUGH DIFFERNCES SHOUL HAVE LTL SENSIBLE EFFECTS THROUGH F48. LARGE AREA OF DRYING ACRS SRN LWR MI. TEMPS PLUMMETING TO NR 10-12F IN CLR SKIES/LIGHT SNOW COVER AND WL TREND TEMPS PD1 LWR. SOME SC ACRS NRN/CNTL IL AHEAD OF WK S/WV AND LTST RUC PROGS KEEPING SFC-8H MSTR DEEP ACRS SRN TIER ZNS UNTIL 18Z WL INDICATE MIX CLDS/SUN S THIS AM AND MSNY N. LTST LAMP ALSO SUPPORTS THIS AND THE COOLER TEMPS. HAVE TRENDED TEMPS GENERALLY COLDER THAN NGM MOS THROUGHOUT. SOME LIGHT SNOW COVER/LIGHT WINDS/CLR SKIES SHOULD AGAIN RADIATE BLO MOS. QUESTION REMAINS WITH FROPA TIMING DY3/4. AVN/MRF MAY BE TOO SLOW. ECMWF CONSISTENTLY FASTER. FOR NOW WL CONT SUN NIGHT RA CHC E AND RA/SN CHC W. NONETHELESS AT LEAST BY DY4 MRF HAS LK-5H DELTA T IN MID 30S LK-8H 23C. OZFFWA IN A FEW. .IWX...NONE PBM in FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS 840 PM CST FRI DEC 17 1999 ...CLOUDS/TEMPS AND BR POTENTIAL CURRENT FORECAST CONCERNS... EVE 11U-3.9U SAT PIC SHOWS CWA ENDURING PATCH OF MOIST GENERALLY ARND 3KFT WITH CIGS LOWERING TWD IFR CONDITIONS AS EVE PROGRESSES. CLEARING EDGE HAS REACHED WRN CWA MAKING IT TO BTWEEN DVL AND GFK AND TO THE E OF JMS BUT PROGRESS APPEARS TO HAVE STALLED AS IT HITS RRV AND ITS S WIND BIAS SO XPCT ANY CLEARING TO BE DELAYED/NON-EXISTANT HERE. HI CLOUD IN ADVANCE OF WKND STORM JUST ARRIVING IN NE MT. SFC ANLYSIS IN CONJUNCTION WITH MSAS FIELDS INDICATE WEAK CIRCULATION ON SASK/MB BORDER WITH WMFNT SLICING THRU CNTRL ND. NIGHTTIME DE-COUPLING MAKING IT HARD TO DETERMINE ACTUAL SFC WIND SHIFT LINE...BUT XPCT MOST OF WARMING TO GO ON ABOVE SFC WITH W WIND SHIFT NEVER MAKING IT TO VALLEY. TEMPS STILL IN 30S IN WRN ND ALTHO KBIS HAS APPARENTLY DE-COUPLED D AND BR HAS DVLPD. TEMPS HAVE BEEN STEADY/INCHING UP ACRSS CWA THRU THE EVE AS CLOUDS HAVE THICKENED AND WAA STRENGTHENED. BAND OF --SHSN SURVIVED MUCH OF EVE ON KMVX 88D ON LEADING EDGE OF STRONG H85-H7 WAA BUT NOW EASING EAST OF CWA SO WILL REMOVE FLURRY MENTION FOR REST OF NGT AS LIFTING MECHANISM IS GONE. RUC AND ETA BOTH PICKED UP WELL ON THE H85 TROF AXIS THAT SHUD BE LOCATED ACRSS CNTRL MN BY 06Z WITH MINI-RIDGE POKING UP OVER ND BEFORE FLOW BUCKLES TO THE SW AGAIN AHEAD OF SAT SYSTEM. ASSOC SUBSIDENCE IN THIS RIDGE SPOT HAS ALLOWED SKY TO CLEAR WRN-CNTRL ND TO DVL AND EVEN WITH SYNOPTIC GRAD INCRSNG...DECOUPLING ALONG WITH TEMPS RISING CLOSER TO TD/S CUD CAUSE SCT AREAS OF BR TO SPREAD E (ESP LOW LYING AREAS) WHERE SKY GOES CLEAR. MODEL SOUNDINGS ALSO INDICATE LOWERING INVERSION WITH MOIST TRAPPED BLO AS IT WARMS ALOFT...AS CURRENTLY ONGOING WITH THE CIGS. PLAN ON TWEAKING SUM SKY CONDITIONS...ESP W OF RRV TO MENTION PARTIAL CLEARING AND AREAS OF BR. CLOUDS TO LINGER LONGEST IN RRV AND EAST SO MCLDY SHUD DO FINE. WILL GO WITH TEMPS SLOWLY RISING REST OF NIGHT...AS LOWS IN AFTN UPDATE ALRDY REACHED. .FGF...WINTER STORM WATCH WRN 2/3RD OF CWFA FOR SUN. SOROKA nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1119 AM EST SAT DEC 18 1999 LOWER CLOUDS ACROSS PARTS OF MY AREA LIFTING N STEADILY. LATEST RUC SUGGEST MY NW COUNTIES MAY HANG ON TO SOME CLOUDS THROUGH THE AFTERNOON. WILL MAINTAIN CLOUDS FOR AREAS N AND W OF A MKG TO RQB LINE. OTHERWISE WILL FORECAST MOSTLY SUNNY CONDITIONS. MOP AT 30 RIGHT NOW...WILL RAISE FORECAST HIGHS FOR TODAY. .GRR...NONE. mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 935 AM EST SAT DEC 18 1999 MAIN AREAS OF PCPN SHOULD REMAIN OFFSHORE THIS AFTN WITH SCT SHRA REACHING THE COASTAL COUNTIES IN THE AFTN. LATEST RUC MATCHES WELL WITH CURRENT TRENDS AND KEEPS PCPN FROM REACHING MOST INLAND AREAS. CLDS BEGINNING TO THIN OUT OVR INLAND AREAS AND WILL LOWER PCPN 10% AND MAY BUMP TEMPS UP A BIT TO ARND 60. CWF: WND DIR NOW COMING ARND TO NE AND WILL INIT AS SO...BUT INCREASE SPDS AND SEAS S OF LITTLE RIVER INLET. WINDS TO SLACKEN SOMEWHAT AS THEY BECOME MORE E THIS AFTN. AREAS OF RAIN DEVELOPING STILL LOOKS GOOD. .ILM...NONE. JFP nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 957 AM EST SAT DEC 18 1999 DISC: 14Z SFC ANLYSIS SHOWS HI PRES OVR VA/NC. LOW PRES ARCS SRN LA/GULF CST. SATELLITE SHOWS QUITE A BIT OF MSTLY MID AND HIGH CLDS ACRS THE ERN HALF OF THE STATE THIS MORNING. SOME SUN ACRS THE NWRN PTN OF THE STATE...BUT CLDS ACRS NRN GA PUSHING NEWD TOWARD THE AREA. WL CONT WITH THE MSTLY CLDY SKIES THRU THE AFT. SATELLITE LOOPS SHOWS MOISTURE STREAMING NE ACRS THE ERN PTN OF THE STATE...DOES NOT LOOK TO BE SHIFTING EWD BUT REMAINING FAIRLY CONSTANT. MORNING RUC APPEARS TO BE A BIT STRONGER WITH S/W ALNG THE LWR MS VALLEY/GULF CST REGION THAN 00Z ETA/AVN RUNS. MAY STILL SEE SOME PCPN YET OVERNIGHT. WITH CLDS CONT OVR THE AREA THIS MORNING...TEMPS NOT RISING TO QUICKLY AND MAY BE SHORT OF AFT FCST. WL CONT TO MONITOR THRU ISSUANCE TIME...BUT MAY NEED TO NUDGE THEM DOWNWARD SLIGHTLY LIKE MID TO UPR 50S. .CAE...NONE. LCV sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 300 PM CST SAT DEC 18 1999 LATEST SFC AND MSAS ANALYSIS INDICATING LIGHT EAST WIND BECOMING MORE SOUTHEASTERLY ACRS CWA AS SFC RIDGE ACRS MI SHIFTS EAST. MSAS ALSO SHOWING PRESSURE FALL BULLEYES APLENTY ACRS UPPER MIDWEST IN RESPONSE TO DEVELOPING SFC TROUGH ACRS PLAINS. CURRENT VIS LOOP SHOWING STRATUS DECK ACRS SOUTH HALF OF CWA IN VARYING THICKNESSES BEING SLOWLY PUSHED NORTHWARD BY VEERING LOW TO MID LEVEL FLOW. VIS LOOP ALSO SHOWING MUCH LARGER DECK ACRS EAST PLAINS AND WEST IA PUSHING EAST ALONG RUC H7-H3 MB THICKNESSES...HEADED TO ENGULF CWA TONIGHT. 12Z UA ANALYSIS INDICATES IMPRESSIVE HEIGHT FALLS AT ALL LEVELS OVER THE NORTHWEST CONUS AHEAD OF NEXT UPSTREAM S/W. MAIN QUESTION THIS FCST PACKAGE CONTINUES WITH ONSET OF NEXT PRECIP EVENT. WATER VAPOR LOOP-W/V INDICATING AT 18Z THAT AVN BEST AT VORT CENTER PLACEMENT ACRS NORTHERN WY...ETA TOO FAR SOUTH. SHORT RANGE MODELS DO DIVERGE IN HANDLING EVOLUTION OF THIS SHARPLY AMPLIFYING SYSTEM IN WAVE STRENGTH AND VORT PLACEMENT THROUGH 48 HRS. SYSTEM GENERALLY CONTINUES TO DEEPEN ON NOSE OF 130-140 KT H3 JET AND ACRS PLAINS BY 12Z MON. NGM BECOMES DEEPER THAN EITHER ETA OR AVN...WHICH ARE MORE SIMILAR WITH HEIGHT FIELDS. PREFER SLOWER AVN HANDLING THAN ETA... THOUGH...WITH SUCH LARGE AND AMPLIFYING SYSTEM AND WILL FOLLOW ETA AND AVN BLEND...WITH EMPHASIS ON AVN WITH SYNOPTIC SCALE FEATURES SUCH AS PVA AND FRONTAL TIMING. TIME SECTIONS SHOW LOW LEVEL SOUTHERLY FLOW ADVECTING HIGHER RHS AND THUS SUBSEQUENTLY STRATUS MAINLY AFTER 00Z TONIGHT...ALTHOUGH FULL COLUMN DEEP MOISTURE DOESN/T ARRIVE UNTIL AFTER 00Z MON. TIME SECTIONS AND FCST SOUNDINGS ALSO SHOW H9-H85 INVERSION SETTING UP TONIGHT...TRAPPING LOW LEVEL MOISTURE/STRATUS THROUGH SUNDAY. WITH HIGH AMPLIFIED SOLUTION...MODELS NOW SLOWER IN BRINGING PRECIP ACRS CWA SUNDAY EVE/NIGHT. INITIAL H85 LOW ASSOCIATED WITH MAIN SHORT WAVE PROGGED TO SHIFT FAR SOUTHERN CANADA TO SOUTHWEST ONTARIO BY 00Z MON. BRISK SOUTHERLY 30 KT H85 FLOW INDUCED AHEAD OF TRAILING COLD FRONT ACRS EAST IA ON SUNDAY REINFORCING H85 WARMING AND INVERSION... AND EVENTUALLY EVEN HIGHER RH/S. WITH SLOWER SOLUTION NOW PROGGED AS SYSTEM APPROACHES...SHORT RANGE MODELS KEEP MOST PRECIP WEST OF DVN CWA THROUGH 00Z MON...WITH BULK OF PRECIP STAYING WEST OF MS RVR THROUGH 06Z MON. BULK OF PRECIP NOW LOOKS TO SHIFT ACRS DVN CWA FROM 06Z-18Z MON...WITH STRONGEST POSITIVE OMEGAS...LOW LEVEL FRONTOGENETICAL FORCING AND DEEP MOISTURE COINCIDING FROM 06Z-12Z MON. AS FOR PRECIP TYPE...EVEN WITH WAA ACRS THE AREA AT VARIOUS LEVELS...BEST BET STILL LOOKS LIKE ALL SNOW. FCST SOUNDINGS...ETA DOES BRING POSSIBILITY OF FREEZING RAIN OR SLEET WITH ONSET AROUND 00Z...AND COOLS TO ALL SNOW BY 06Z. AVN LOOKS LIKE A SNOW-RAIN MIX AT 00Z QUICKLY COOLING TO AN ALL SNOW SOUNDING BY 06Z AS WELL. AGREE WITH LOT THAT NGM APPEARS TOO WARM IN IT/S THICKNESS PATTERNS AND WOULD KEEP MAINLY RAIN THROUGH 06Z MON. H85 TEMPS ARE SIMILAR WITH ETA AND AVN -2 C SUPPORTING MAINLY SNOW AND WARM +1 NGM RAIN. 1000- H85 MB CRITICAL THICKNESSES TELL SAME STORY SUNDAY EVENING WITH AVN AND ETA COOL ENOUGH FOR ALL SNOW...EVEN WITH SEMI-SATURATED VERTICAL PROFILE...WHILE NGM SUPPORTS RAIN. WILL GO WITH COOLER AVN AND ETA... AND THROUGH IN POSSIBILITY OF MIX AT ONSET. IF SYSTEM STRENGTHENS AND WRAPS WARMER AIR INTO IT...COULD BE INTERESTING. LOOKING AT ISENTROPICS ON 290 K SFC...BEST LIFT AGAIN PROGGED ACRS AREA SUNDAY BEFORE PRECIP ARRIVES. AGAIN...HIGH COND PRES DEFICITS SHOW THAT INITIAL LIFT GOES INTO SATURATION PROCESS. ETA GARCIA METHOD LOOKS LIKE 1-3 INCHES FROM 00Z-12Z MON...WHILE AVN GOES 2-4 INCHES BY 15Z MON MORNING. WITH POSSIBILITY OF MIX CUTTING DOWN ON AMOUNTS...WILL AGAIN ONE MORE TIME MENTION THAT SOME ACCUMULATION LIKELY AND NOT GO WITH AMOUNTS YET. H85 FRNT PASSES WITH STIFF H85 CAA ACRS CWA BY 12Z MON. WITH -20 C H85 COLD POOL POISED UPSTREAM TO SWEEP ACRS CWA LATER ON MON...AND AVN DEEPENS SFC LOW TO THE NORTHEAST OVER GRT LKS INDUCING TIGHTENING GRADIENT ACRS IA...LOOKS LIKE COLD WINDY DAY ON MONDAY WITH S-] AND BS. INTERESTING THAT AVN ISENTROPIC ANALYSIS POINTS TO ANOTHER QUICK SHOT OF LIGHT SNOW WITH GOOD LIFT CENTERED AROUND 06Z TUE...ALTHOUGH SPECIFIC HUMIDITIES PINT TO ONLY 1-2 INCHES OF ADDITIONAL ACCUMULATION POSSIBLE BY TUE MORNING. ...EXTENDED...NEXT TUE-WED-THU... EUROPEAN...CANADIAN...AND MRF ALL SIMILAR IN HANDLING HIGH AMPLITUDE L/W TROUGH OVER THE CENTRAL CONUS ON TUE. ALTHOUGH WESTWARD EXTENT OF HIGHER RH/S AND WRAP-AROUND FROM NORTHEASTWARD PROGRESSING SYSTEM IS BASICALLY EAST OF CWA ON TUE...MRF AND CANADIAN CONTINUE WITH IMPRESSIVE PVA ACRS CWA AS ANOTHER VORT DROPS THROUGH MID BASE PORTION OF L/W. THIS MAY BE ENOUGH TO MILK OUT LIGHT SNOW OR FLURRIES AND MRF POPS SUPPORT THIS. H85 COLD POOL OF AT LEAST -15 TO -18 C FILTERS ACRS CWA BY LATE TUE AND TUE NIGHT. FMR HIGHS FOR TUE LOOK OKAY...BUT TUE NIGHT/WED MORNING LOWS MAY BE OPTIMISTICALLY WARM WITH SUCH STRONG LOW LEVEL CAA AND SNOW COVER. EXTENDED MODELS THEN DIVERGE ON WED AS EUROPEAN NOW FLIP-FLOPS AND SHIFTS CLIPPER SYSTEM ACRS WEST IA INTO MO BY WED MORNING. THIS LOW IS THEN PROGGED TO SHIFT EAST ACRS OH RVR VALLEY THROUGH WED NIGHT. THIS SCENARIO WOULD DEFINITELY LEAD TO ANOTHER SNOW EVENT FOR THE DVN CWA...BUT MRF CONTINUES IT/S DRY WED SOLUTION AS SFC RIDGE OCCUPIES MID MS RVR VALLEY AND SEMI-SPLIT FLOW UPPER AIR PATTERN DEVELOPING ACRS L/W. NORTHERN STREAM WAVE SHIFTS LIGHT SNOW TO THE NORTH ACRS NORTHERN MN INTO THE WEST GRT LKS WED AND WED NIGHT...BUT THEN SHIFTS ACTIVITY SOUTHEAST ACRS CWA BY THU MORNING AND FOR THURSDAY. AS OF NOW JUST LOOKS LIKE LIGHT SNOW/FLURRIES. CANADIAN IN-BETWEEN...BUT CLOSER TO EURO AND HINTS AT CLIPPER AFFECTING PART OF AREA WED. WITH UNCERTAINTY...WILL LEAN TO MORE CONSISTENT MRF AND KEEP WED DRY FOR NOW...ALTHOUGH IT MIGHT COME BACK AND BITE ME. WILL THROUGH IN CHANCE OF S- ON THURSDAY LEANING TOWARD MRF CLIPPER. EURO ALSO HAS SECONDARY TROUGH INDUCING H85-H7 LAYER WAA AND ISENTROPIC LIFT ACRS AREA THURSDAY ALSO HINTING AT S- POTENTIAL. FEEL FMR NUMBERS MAY BE TOO WARM FOR THU AND WILL UNDERCUT SOMEWHAT. COORDINATED WITH LOT...THANX. .DVN... IA...NONE. IL...NONE. MO...NONE. HLADIK il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 335 PM EST SAT DEC 18 1999 MAIN PROBLEM DEALS WITH PRECIPITATION TYPE FOR MONDAY ACROSS MY NORTHWEST ZONES. MODELS DIFFER ON HOW MUCH WARM LOW LEVEL AIR ARRIVES AHEAD OF THE NEXT STORM HEADING OUR WAY FOR SUNDAY NIGHT AND MONDAY. NGM IS THE WARMEST WHILE THE ETA IS COOLEST. I AM LEANING TOWARD THE AVN...WHICH HAS SHOWN DECENT CONTINUITY FROM THE PREVIOUS RUN AND IS A COMPROMISE BETWEEN THE ETA AND NGM. STILL...I FEEL THAT THE AVN IS SLIGHTLY TO WARM WITH THIS SYSTEM. LOOKING A THICKNESS VALUES AND FORECAST SOUNDINGS...MAINLY A LIQUID SCENARIO SHOULD WORK THROUGH MONDAY...BUT MY NW COUNTIES COULD SEE A MIX OR CHANGEOVER TO SNOW. TO MAINTAIN CONTINUITY WITH PREVIOUS FORECAST ...WILL KEEP SOME POTENTIAL FOR SNOW IN MY NW COUNTIES ON MONDAY. AS WITH THE PREVIOUS SYSTEMS...TERRAIN COULD COME INTO PLAY AS WELL. AS FOR TONIGHT...WARM AIR ADVECTION IN THE LOW LEVELS BEGIN. LOWER CLOUDS THAT HAVE PLAGUED MY NW COUNTIES...HAS SHOWN SOME DECREASE ALONG THE SOUTHERN EDGE ACCORDING TO THE PAST COUPLE OF VISIBLE PICTURES. RUC MODEL 925 MB RH CONFIRMS THIS AND WILL WORD MY NORTHWEST COUNTIES AS BECOMING MOSTLY CLEAR THIS EVENING. TEMPERATURES WILL BE A TOUGH CALL. AFTER LAST NIGHT...WHEN TEMPERATURES DROPPED INTO THE SINGLE DIGITS IN AREAS THAT STAYED CLEAR...FEEL THAT MANY PLACES COULD DROP INTO THE TEENS. THIS IS WHAT I AM FORECASTING. IF THE SOUTHEAST WIND PERSISTS...MANY PLACES MAY STRUGGLE TO GET THIS LOW. THEN FOR SUNDAY...TIME SECTIONS FOR RH...SHOW INCREASING MOISTURE ARRIVING AND WILL WORD THE ZONES AS INCREASING CLOUDS. HIGHS GENERALLY IN THE UPPER 30S TO NEAR 40. ISENTROPIC LIFT INCREASES SUNDAY NIGHT AND AN AREA OF PRECIPITATION AND LOWER CLOUDS EXPECTED TO LIFT UP FROM THE NORTH. AM THINKING TEMPERATURES WILL BE ABOVE FREEZING WHEN THE PRECIPITATION ARRIVES...BUT IF WE START THE NIGHT OFF MOSTLY CLEAR...SOME PLACES COULD DROP BELOW FREEZING. THIS COULD LEAD TO SOME FREEZING OF THE RAIN ON COLDER SURFACES. WILL LEAVE THIS OUT FOR NOW. FORECAST SOUNDINGS SUGGEST WARM LAYER WILL KEEP SNOW AND SLEET OUT OF THE PICTURE. THEN FOR MONDAY...UPPER FLOW BECOMES PARALLEL TO THE SURFACE FRONT...SUGGESTING A VERY SLOW MOVEMENT. WE ARE EXPECTED TO BE ON THE WARM SIDE OF THIS FEATURE...AND THUS MAINLY RAIN IS FORECASTED. ALOFT...A VERY STRONG JET MAX WILL BE IN PLACE. WE ARE TO BE IN THE DIVERGENT LEFT QUADRANT OF THIS FEATURE...WHICH COULD ACT TO ENHANCE PRECIPITATION VALUES...ESPECIALLY LATER IN THE DAY. GENERALLY HIGHS IN THE UPPER 30S TO LOW 40S EXPECTED. EXTENDED FORECAST LONG RANGE MODELS SHOW A LARGE LONG WAVE TROF OVER THE CENTRAL US AT THE BEGINNING OF THE PERIOD. THE CANADIAN AND ECMWF MODELS ARE THE QUICKER SOLUTIONS AT THE BEGINNING OF THE EXTENDED PERIOD. BOTH SHOW ANOTHER SHOT OF COLD AIR WITH 1000-500 THICKNESS VALUES NEAR 510. BOTH THE 12Z AVN AND THE MRF ARE A LITTLE SLOWER BRINGING IN THE COLD AIR. ATTM WILL FOLLOW THE SLOWER SOLUTIONS. WITH THE MODELS SHOWING THE JET DIVING TOWARD THE GULF...I LIKE THE AVN AND MRF SOLUTIONS OF SHOWING A WAVE DEVELOPING IN THE LOWER MS VALLEY AND MOVING NORTH. THIS SHOULD SLOW THE EWD PROGRESSION OF THE COLD FRONT A LITTLE BIT. WILL LOOK FOR FROPA MONDAY EVENING FOLLOWED BY FALLING TEMPS MONDAY NIGHT WITH CAA. FCST SOUNDINGS SHOW INVERSION HEIGHTS AROUND 5K FEET MONDAY NIGHT. SO ANY LES THAT DOES DEVELOP SHOULDN/T GET TOO CARRIED AWAY EVEN THOUGH H85 TEMPS DROP FROM NEAR 0 AT 00Z TO -9C ALONG THE LAKESHORE AT 12Z. PROFILE DRYS OUT QUITE A BIT BY WED MORNING BEFORE MOISTENING RAPIDLY WED NIGHT AHEAD OF THE NEXT SYSTEM...BUT TEMPS REMAIN WELL BELOW FREEZING. WILL GO PARTLY CLOUDY ON WED AND MO CLDY WITH CHC OF SNOW ON THU AS WAA DEVELOPS IN SW FLOW. WILL GO CLOSE TO MRF TEMPS. .GRR...NONE. mi