INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE HANFORD CA 330 AM PST MON DEC 23 2002 STRATUS AND FOG...ALONG WITH FROST...IS THE MAIN CONCERN THIS MORNING AND THROUGH PARTS OF TODAY. AS OF 300 AM...VALLEY TEMPERATURES WERE RANGING FROM 32 TO 39. THE FOG HAS BEEN VERY PATCHY AND MOSTLY EAST OF HIGHWAYS 99 AND 43. YET...VISIBILITIES HAVE REMAINED ABOVE A QUARTER MILE IN MOST LOCATIONS WITH THE HANFORD/VISALIA AREA IN THE WORST PART OF THE FOG. RUC ANALYSIS COMBINED WITH IR SATELLITE IMAGERY SHOWS THE UPPER LOW NOW PUSHING THROUGH THE DESERT SOUTHWEST. OVER THE WEST COAST...THE DEVELOPING RIDGE IS PUTTING THE CWFA UNDER A DRY NORTHERLY FLOW. THIS PATTERN WILL SUPPORT THE REDEVELOPMENT OF FOG AND FROST MONDAY NIGHT BEFORE THE INTRODUCTION OF THE NEXT STORM SYSTEM. MODELS CONTINUE THEIR GOOD AGREEMENT WITH TIMING THE NEXT PACIFIC STORM INTO THE CENTRAL VALLEY TUESDAY AFTERNOON. WHILE NOT AS STRONG AS THE PREVIOUS STORM...WILL EXPECT RAIN AND SNOW OVER THE DISTRICT FOR A SHORT DURATION OF TIME. A RATHER STRONG JET STREAM WILL DRIVE THE STORM THROUGH THE AREA QUICKLY ALLOWING THE DISTRICT TO DRY OUT CHRISTMAS DAY. YET...ANOTHER STORM BEHIND THE FIRST WILL RE-INTRODUCE PRECIP OVER THE DISTRICT LATER WEDNESDAY INTO THURSDAY. WITH A STRONG JET ON TUESDAY STORM...QPF WILL REMAIN LIGHT AND BELOW ADVISORY CRITERIA. THE SECOND STORM LOOKS MORE IMPRESSIVE WITH BETTER POSSIBLE PRECIP TOTALS. MOLINA IN THE EXTENDED...WILL CONTINUE TO LEAN TO THE WETTER SOLUTIONS THAT INDICATE PERSISTENCE OF STORMY PATTERN. GFS PROGS THE NEXT SYSTEM TO BE A WET ONE FOR LATER THURS/FRI. FOR THE WEEKEND...NO ONE MODEL TO HANG A HAT ON. GFS TRYING TO BUILD A RIDGE ALONG THE WEST COAST BY SUN...THE UKMET BUILDS IT SAT...BUT EURO AND GEM KEEP THINGS MORE UNSETTLED IN FAST ZONAL FLOW. IN KEEPING WITH PERSISTENCE...WILL FOLLOW THE FLATTER FASTER EURO SOLUTION FOR NOW...AND JUST BROADBRUSH CHANCE OF PRECIP SAT/SUN. NOT MUCH CONFIDENCE DAYS 6-7. BINGHAM .HNX...NONE. ca WEST CENTRAL AND SOUTHWEST FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN 934 AM EST MON DEC 23 2002 MORNING RAOB DATA SHOWS INCREASING LOW LEVEL MOISTURE BELOW A STRONG SUBSIDENCE INVERSION ~850MB...SO EXPECT TO SEE A FEW MORE CLOUDS DEVELOP ACROSS THE FA DURING THE AFTERNOON. DEVELOPING EAST-SOUTHEAST WIND FLOW AROUND THE SURFACE HIGH MOVING OFF THE SE U.S. COAST WILL ALLOW TEMPERATURES TO CLIMB TO ABOVE SEASONAL LEVELS (MID/UPPER 70S) THROUGHOUT WITH INCREASING DEW POINTS. ONGOING ZONES COVER ALL OF THIS...SO NO MORNING UPDATE PLANNED. MARINE...C-MAN AND OFFSHORE BUOY TRENDS AS WELL AS THE LATEST RUC GUIDANCE SUPPORTS THE ONGOING PACKAGE FOR THE AFTERNOON...SO NO CHANGES EXPECTED IN THE 1030 AM UPDATE. .TBW...NONE. MCMICHAEL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 229 PM MST MON DEC 23 2002 FORECAST CONCERNS ARE EXTENT AND AMOUNT OF SNOWFALL TONIGHT... TEMPERATURES THROUGHOUT...AND STRENGTH OF NORTHERN STREAM SYSTEM ON WEDNESDAY NIGHT AND THURSDAY. SATELLITE SHOWING POWERFUL JET STREAMING ACROSS THE PACIFIC. FLOW IS AMPLIFIED FROM EASTERN PACIFIC INTO NORTH AMERICA. SYSTEM OVER THE DESERT SOUTHWEST IS STARTING TO KICK OUT. QUESTION IN THE SHORT TERM IS HOW FAR NORTH THIS SYSTEM WILL MOVE AND ITS AFFECT ON THE SNOWFALL FORECAST. AT JET LEVEL...160-180 KNOT JET OVER THE PACIFIC. THE GFS LOOKED TO DO THE BEST ON THIS. 100-120 KNOT JET ON WEST SIDE OF DESERT SOUTHWEST SYSTEM. THE MODELS ARE TOO LOW WITH THIS JET SEGMENT. THE GFS/ETA DID THE BEST WITH THE ETA SLIGHTLY BETTER. AT MID LEVELS...ETA WAS THE WORST OF THE BUNCH. IT WAS TOO FAR NORTH AND EAST WITH CENTER OF DESERT SOUTHWEST SYSTEM. BASED ON HEIGHT ANALYSIS AND SATELLITE...THE GFS WITH THE NGM SECOND MATCHED UP BETTER WITH THIS SYSTEM...AND WAS FURTHER SOUTH AND WEST WITH FEATURES THROUGH SIX HOURS AT 500 MB. GFS AND RUC WERE ALSO DOING WITH 700 MB CIRCULATION NEAR EASTERN NEW MEXICO AND WEST TEXAS BORDER. AT LOW LEVELS...MODELS TENDED TO BE A LITTLE COLD. OVERALL... GFS DID A LITTLE BETTER. WILL BE BLENDING THE RUC/GFS FOR TONIGHT AND THEN LEAN TOWARD THE GFS FOR THE REST OF THE SHORT TERM. HOWEVER...WILL MODIFY IT BASED ON KNOWN BIASES...ESPECIALLY ON ITS COOL BIAS. FOR TONIGHT/TUESDAY...IF JET PROGS/HEIGHT FALL ANALYSIS IS CORRECT... SOUTHWEST SYSTEM SHOULD START KICKING OUT LATE THIS AFTERNOON AND EARLY THIS EVENING WITH BULK OF ENERGY GOING THROUGH WEST TEXAS. SATELLITE SHOWING DRY SLOT PUNCHING FROM THE SOUTH AS SOUTHERN PLAINS CONVECTIONS HAS MOVED TO THE EAST. RUC/GFS AND EVEN THE ETA AGREE ON KEEPING THE DEEPEST MOISTURE AND BEST LIFT OVER THE SOUTHERN SIX COUNTIES. MOISTURE/LIFT DECREASES EARLIEST IN GOVE AND LOGAN WITH LIFT SHIFTING TO THE SOUTHWEST SECTION FOR THE REST OF THE EVENING. HAVE LITTLE TO NO LOW LEVEL UPSLOPE HELP. TO MAKE THINGS SIMPLE WILL PUT SOUTHERN FIVE KANSAS COUNTIES TOGETHER AND CHEYENNE BY ITSELF. BECAUSE DRY SLOT AND SOUTHERN PLAINS CONVECTION ROBBING MOISTURE...THINK FOR NOW 1 TO 3 INCHES LOOKS GOOD WITH GREELEY AND WICHITA GETTING THE BEST OF IT. WILL THEREFORE BE ISSUING NO HIGHLIGHTS. MID AND UPPER LEVEL RIDGING... DOWNWARD MOTION...AND DRIER WILL PREVAIL FURTHER NORTH. WILL HAVE NOTHING IN THE NORTH WITH LOWER CHANCE POPS IN THE MIDDLE. RIDGING WILL PREVAIL DURING THE DAY. SKIES SHOULD CLEAR DURING THE DAY. PLAN GOING NEAR TO MAV MOS. FOR TUESDAY NIGHT/WEDNESDAY...RIDGING AND WESTERLY FLOW ALOFT WILL KEEP IT DRY WITH ONLY SOME CLOUDS EXPECTED. GOOD RADIATIONAL CONDITIONS EXPECTED AND MAV MOS LOOKS REASONABLE. WEAK DOWNSLOPE WINDS EXPECTED DURING THE DAY. MAV MOS LOOKS A LITTLE COOL CONSIDERING THE AMOUNT OF SUN EXPECTED AND SOME DOWNSLOPE. HOWEVER... ETA IS PROBABLY TOO WARM. WILL TEND TO GO NEAR TO SLIGHTLY ABOVE MAV GUIDANCE. FOR WEDNESDAY NIGHT/THURSDAY...GFS IS BRINGING DOWN SYSTEM THROUGH NORTHERN PLAINS DURING THIS TIME. GFS HAS HAD A TENDENCY OF OVERBLOWING THIS SYSTEMS LATELY. HOWEVER...CAN SEE THE POTENTIAL FOR DEEPING AND STRENGTHENING OF SYSTEM DUE TO UPPER LEVEL RIDGING AND JET STRUCTURE EXPECTED. THE MAIN CONCERN WITH THIS SYSTEM WILL BE ANOTHER COLD SHOT WITH BREEZY TO WINDY CONDITIONS...AND WILL HAVE TO BE MONITORED CLOSESLY. AVN LOOKS A LITTLE COLD. WILL HAVE SOME SUN AND SOME DOWNSLOPING WINDS TO OFFSET COLD AIR ADVECTION. WILL TEND TO GO NEAR TO SLIGHTLY ABOVE NUMERICAL GUIDANCE. IN THE 4 TO 7 DAY PERIOD...ECMWF AND GFS LOOK TO BE DOING THE BEST AS OF THIS MORNING. IF ANYTHING...THEY ARE PROBABLY TOO FAST IN KICKING OUT CURRENT SOUTHWEST SYSTEM. FRIDAY AND SATURDAY LOOK DRY AND WARMER THAN GUIDANCE AHEAD OF NEXT SYSTEM/JET MOVING IN SATURDAY NIGHT AND SUNDAY. ECMWF IS MORE AMPLIFIED THAN PREVIOUS RUN DURING THIS TIME PERIOD...BUT DOES NOT REFLECT IT DOWNSTREAM. GFS/MRF SHOW A STRONGER SYSTEM MOVING THROUGH SATURDAY NIGHT/SUNDAY. THINK FLOW WILL BE MORE AMPLIFIED THAN CURRENTLY PROGGED WITH SYSTEM STILL COMING OUT OF THE NORTHWEST. CURRENTLY SUNDAY IS DRY WITH LOW POPS ON THE GUIDANCE. AT THIS TIME...WILL KEEP IT DRY BUT WILL HIT THE CLOUDS HARDER AND LOWER THE TEMPERATURES SOME. EVEN WITH STRONGER SYSTEM MOVING THROUGH SUNDAY...THE GUIDANCE FOR MONDAY LOOKS TOO COLD...AND WILL GO NEAR CLIMOTOLOGY AT THIS TIME. .GLD...NONE. BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 800 PM CST MON DEC 23 2002 WELL...RUC SEEMS TO BE VERIFYING WITH MOVEMENT OF FRONT...A LITTLE FASTER THAN THE MESOETA I USED. BUT MESOETA IS VERIFYING WELL WITH THE 2ND ROUND OF CONVECTION STREAMING IN FROM FTW AND SAT AREAS. THESE STORMS COULD BE HAILERS GIVEN THEIR ELEVATED NATURE BEHIND THE FRONT AND THE LIKELIHOOD OF COLDER AIR ALOFT WITH THEM. ANYHOW...NO NEED TO LOWER POPS OUT WEST. ADJUSTED WINDS AND TEMPS IN SOME GROUPS. NEW TORNADO WATCH COVERS SAME COUNTIES/PARISHES...EXTENDED TIL 3 AM BUT TX PORTION IS INCREASINGLY BEHIND THE FRONT PUSHING SOUTHWARD THROUGH OCH AND LFK ALREADY. 17 .SHV...TORNADO WATCH TIL 3 AM TXZ152-153-165>167 LAZ010-011-013-017>022. FLASH FLOOD WATCH TONIGHT SOUTH OF I 30. la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 945 PM EST MON DEC 23 2002 00Z RAOBS/WV LOOP AND RUC ANLSYS SHOW SPLIT FLOW ACRS NAMERICA. SLUGGISH NRN BRANCH UPR LO THAT WAS OVR ONTARIO THAT LAST COUPLE OF DAYS IS NOW EASING INTO QUEBEC...AND CONFLUENT NW FLOW ALF/H5 NVA IN THE WAKE OF THIS SYS IS ENVELOPING THE NW GRT LKS AS SHRTWV RESPONSIBLE FOR THIS MRNG'S SGNFT LES MOVES SE THRU THE CNTRL GRT LKS. A WEAKENING CYC WNW FLOW LINGERS OVR THE NW LKS...WITH CONSIDERABLE LO CLD OVR THE UPPER PENINSULA TRAPPED UNDER INVRN AT H85 AS DEPICTED ON 00Z GRB SDNG. THERE IS ANOTHER SHRTWV OVR CNTRL MN...AND SOME -SN IS FALLING OVR THE MN ARROWHEAD DESPITE DRY AIR SHOWN ABV H8 ON THE 00Z INL SNDG. ALTHOUGH LVLS BLO H8 AT INL ARE MOIST...EVEN ABV SHARP INVRN AT H9...THERE HAS BEEN CLRG FM CKC- CYQT AND ACRS WRN LK SUP UNDER THE H5 NVA. THIS SHRTWV APPEARS TO BE DRIFTING ESE. LLVL WNDS OVR MUCH OF THE CWA HAVE TURNED MORE W WHILE WNDS OVR ERN LK SUP REMAIN NW. MQT 88D SHOWS SOME WEAK ECHOES (GENERALLY LESS THAN 16 DBZ) STREAMING FM THE ERN KEWEENAW PENINSULA INTO ERN ALGER COUNTY IN THE CONFLUENCE BTWN THESE AIRSTREAMS. MAIN FCST CONCERNS DURG THE OVRNGT ARE CLD TRENDS/PCPN CHCS/TEMPS. 00Z RUC SHOWS UPR HGTS RISING OVRNGT OVR THE FA AS SE CNDN UPR LO CONTINUES TO SHIFT E. WITH MN SHRTWV FCST TO MOVE INTO NCNTL WI OVRNGT WITH SOME WEAK PRES FALLS THERE...PRES GRADIENT/CYC FLOW PROGGED TO CONT RELAXING. ALTHOUGH LLVL CONFLUENCE ZN LIKELY TO LINGER OVR SRN LK SUP WITH MORE NW FLOW OVR ERN LK AND WLY FLOW OVR CWA...NVA/LWRG INVRN HGTS (H85 TEMPS FCST TO INCRS TO ARND -8C...TO HI FOR LES WITH WATER TEMPS NR 4C) AND DRY H7 AIR WL RESTRICT PCPN INTENSITY EVEN OVR THE BNDRY. WL CALL FOR SCT -SHSN ARND BNDRY...BUT NOTHING MORE THAN FLURRIES ELSEWHERE. CONCERNED THAT NVA/LWRG INVRN HGTS WL CAUSE SOME -FZDZ OVR UPSLOPE AREAS OF THE KEWEENAW PENINSULA AS 18Z ETA FCST SDNGS FOR CMX SHOW TEMPS WITHIN MOIST LYR BLO STRENGTHENING INVRN ABV -10C. THESE SAME DYNAMICS MAY ALSO CAUSE SOME PARTIAL CLRG OVR AREAS THAT DOWNSLOPE WITH A W WIND...AS OBSVD UPSTREAM FM CKC TO CYQT. 18Z ETA FCST INDICATES SUBSIDENCE EVEN BLO INVRN OVRNGT. BUT WL NOT CHG MOCLDY FCST AS LATEST CKC-CYQT OBS SHOW HOLES IN CLD HAVE FILLED IN. ALTHOUGH RUC SHOWS INCRSG H5-3 QVECTOR CNVGC OVR ESPECIALLY THE WI BORDER ZNS LATE TNGT...FCST H7 RH IS SO LO THAT ANY UVV ACCOMPANYING THESE DYNAMICS WL BE UNABLE TO SATURATE MID TROP. IN FACT...UVV MAY WEAKEN INVRN THESE AREAS AND ALLOW SC TO BRK. COORDINATED WITH GRB. AFDMQT FM DAYSHIFT FOR LATER PDS... LONGER TERM REMAINS QUIET...ONLY MAJOR CONCERN IS ADDITIONAL LES. IT IS UNLIKELY THAT INLAND AREAS (ERN IRON/DICKINSON/MENOMINEE/SRN DELTA COUNTIES) WILL HAVE A WHITE CHRISTMAS THIS YEAR. SFC FLOW REMAINS NW ON TUESDAY...BUT LOW LVL INSTABILITY (DELTA-T ONLY AROUND 10C IN MORNING) AND CVRG IS LACKING. WILL PROBABLY SEE SOME LAKE CLDS MOVING INLAND AGAIN DURING THE DAY AS WINDS TURN A LITTLE MORE NLY...BUT THAT WILL PROBABLY BE ABOUT IT. THOUGHT ABOUT TAKING OUT POPS IN THE ZONES...BUT HAVE DECIDED TO KEEP THEM BUT AS 850MB TEMPS DO LOWER SLIGHTLY BEHIND THE WAVE WHICH MOVES THRU THE AREA IN THE MORNING. OTHERWISE...EXPECT NR NORMAL TEMPS ON TUESDAY WITH MUCH WEAKER WIND SPEEDS AS INCREASED ANTICYCLONIC FLOW MOVES INTO THE AREA. FOR TUESDAY NIGHT...NO MAJOR FEATURES TO LATCH ONTO WITH WEAKENING LOW LVL FLOW. MODELS SUGGEST THAT BEHIND THERE WILL BE ADDITIONAL DRYING DURING THE EVENING...ALTHOUGH THERE IS IS A WEAK WAVE THAT IS MOVING THRU THE NW FLOW ALOFT THIS MAY TRY TO LIFT THE INVERSION SLIGHTLY...BUT REALLY NO MOISTURE WITH THE WAVE. SINCE WINDS WILL BE 340-350...THERE IS A CHANCE THAT EASTERN MQT COUNTY COULD GET SOME LIGHT LES. BIG LIMITING FACTOR WILL BE VERY MARGINAL LOW LVL INSTABILITY WITH DELTA-T VALUES AROUND 14C. OTHERWISE...FOR INLAND AREAS IT LOOKS DRY. SINCE FLOW WILL BECOME A LITTLE MORE NLY OVERNIGHT...AND DRY AIR FILTERS INTO THE CWFA ABV THE INVERSION...THERE MAY BE SOME FREEZING DRIZZLE IN THE UPSLOPE AREAS OF THE WEST...AND EASTERN MQT COUNTY. FOR CHRISTMAS DAY...LOOKS LIKE THE LOW OVER THE OH VLY WILL JUMP TO THE ATLC COAST NR NEW JERSEY (ETA PROB SUFFERING CONVECTIVE FEEDBACK PROBS...THUS MORE NW SOLN). THIS WILL ENABLE HIGH PRES TO BUILD INTO THE REGION...ALONG WITH DRY AIR. CONTINUED N-NW FLOW ALOFT WILL MAY LEAD TO SOME LIGHT LAKE EFFECT SNOW/FLURRIES. WITH CONTINUED DRYING ALOFT THOUGH...THERE MAY ALSO BE SOME FREEZING DRIZZLE INSTEAD OF FLURRIES/LIGHT SNOW...ESPECIALLY SINCE -10C ISOTHERM IS INTO THE DRY AIR. HOWEVER...SOME UPR LVL MOISTURE IS PROGGED TO MOVE INTO THE WESTERN AREA LATE...PROBABLY HELPING TO SHUT OFF ANY FREEZING DRIZZLE. MAINLY JUST FLURRIES IN THE AFTN OVER THE W AND NE AREAS AS FLOW STARTS TO BACK AROUND AND H8 TEMPS INCREASE. WILL GO DRY FOR CHRISTMAS NIGHT AND THU...ALTHOUGH THE ETA SHOWS A WEAK WAVE MOVING THRU THE AREA AGAIN WED NIGHT...TURNING THE WINDS NWLY AGAIN. HOWEVER...IT WILL JUST BE TOO WARM AT 850MB TO WARRANT ANY LES TYPE POPS. OTHERWISE ON THU...IT WILL BE MOST LIKELY WARMER STILL...WITH TEMPS APPROACHING 30F SINCE 850 TEMPS WILL BE RISING TO -3C. FOR THE EXTENDED (FRI-MON)...NO MAJOR CHANGES PLANNED. MODELS AND ENSEMBLE MEMBERS ARE IN FAIR AGREEMENT IN BROAD WLY FLOW CONTINUING ON FRIDAY IN WAA...LEADING TO PTCLDY DAY WITH TEMPS ABV NORMAL AS H8 TEMPS RISE TO -3C. THE OPERATIONAL GFS SHOWS A WEAK WAVE MOVING THRU THE AREA FRI...AND SHOWS SOME LIGHT PCPN. SYSTEMS SIMILAR TO THIS SO FAR THIS YEAR HAVE BEEN DRY...SO WILL CONTINUE WITH A DRY FCST. HOWEVER...BEHIND THE WAVE ON SAT...SWLY FLOW KICKS IN WITH H8 TEMPS WARMING TO NEAR -1C (PROBABLY WARMER IN REALITY) ACCORDING TO THE OPERATIONAL GFS...SO WILL GO WITH WARMER TEMPS THAN MRF MOS SUGGEST. COULD EVEN SEE LOWER 40S IF THE DEEP TROUGH OVER THE EPAC VERIFIES...BUILDING HEIGHTS OVER THE UPR MIDWEST. MIGHT HAVE ANOTHER WAVE MOVE THROUGH...BUT IT NOW LOOKS RELATIVELY DRY FOR SATURDAY....SO WILL TAKE OUT ANY POPS. OTHERWISE...THE OPERATIONAL GFS IS TRYING TO PHASE THE NRN AND SRN STREAM ENERGY IN DAY 6/7 AND DEVELOP A LOW TRACKING UP THE MS VALLEY THRU LOWER MICH. THIS WOULD GIVE A GOOD LAKE ENHANCED AND SYNOPTIC EVENT FOR UPPER MICH IF IT VERIFIES. GFS ENSEMBLES SUPPORT THIS SOMEWHAT ALTHOUGH PROBABLY WEAKER AND A LITTLE SLOWER...SO WILL PLAN ON CHC SNOW SUN AND MON AS WELL. WOULD NOT BE SURPRISED IF IT ENDS UP BEING MORE OF A SRN STREAM STORM. OTHER THAN SLIGHTLY WARMER THAN NORM TEMPS FRI AND SAT...TEMPS NEAR NORMAL FOR REMAINDER OF WKND. .MQT...NONE. KC mi SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1020 AM EST MON DEC 23 2002 LATEST RUC AND 88D ANALYSIS SHOWS AN ENHANCED CONVERGENCE SETTING UP ALONG I69. 1000-850 WINDS REMAIN FROM THE WEST NEAR 30 KTS WITH 850 TEMPS STILL -10 TO -12...DELTA T/S RIGHT AROUND 13C. INVERSION HEIGHTS FROM SURROUNDING UPPER AIR SIGHTS ARE NEAR 850 MBS BUT WELL WITHIN A GOOD ICE NUCLEATION PARAMETERS. WE WILL UPGRADE THIS REGION TO OCCASIONAL SNOW WITH ACCUMULATIONS LESS THAN 1 INCH. AS SHORT WAVE AND COLD FRONT MOVE DOWN ACROSS NORTHERN LOWER THIS AFTERNOON...WE SLOWLY WARM UP 850 TEMPS AND DECREASE AVAILABLE MOISTURE ACROSS THE LAKE...TO REDUCE SNOW BACK TO FLURRIES PER NEW RUC GUIDANCE. OTHERWISE NO OTHER CHANGES AT THIS TIME. LOTS OF TALK ABOUT TOMORROWS SNOW EVENT...LATEST 12Z ETA IS A LITTLE FURTHER NORTH WITH RESPECT TO SFC LOW TRACK ALTHOUGH UPPER LEVELS DO NOT SUPPORT POSITION. WITH THESE POSITIVE TILTED TROFS...IT WOULD BE DIFFICULT TO HAVE THESE SYSTEMS COME THIS FAR NORTH. WE WILL AWAIT FOR THE GFS BEFORE MAKING DECISIONS. ZFP AND GRIDS ON THE STREET. .DTX...GALE WARNING...TODAY...ALL OF LAKE HURON. BGM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 915 PM CST MON DEC 23 2002 SN ASSOCD WITH WAA/MID LVL FRONTOGENESIS IS MOVG EWD AT A PRETTY GOOD CLIP WITH MID LVL DRYING ALREADY OCCURING OVR SWRN MO. HV SEEN AT LEAST 3 DISTINCT BANDS AT TIMES OVR SE MO INTO SRN IL THIS EVNG AND THIS HAS HELPED PRODUCE SOME HEFTY TOTALS ACRS THE ERN OZARKS...8 INCHES IN SVRL LCTNS TO ALMOST 11 IN POTOSI. (WE WL SEND A LIST OF ACCUMS BY 945 PM.) AREA OF NEG EPV ARND H5 SUGGESTS CSI IS CONTRIBUTING TO BANDING AND INTENSE MESOSCALE UPDRAFTS. ANYWAY THIS RGN OF LIFT WL SHIFT EAST OF THE MS RVR BY MIDNIGHT IF NOT BFR. QUESTION THEN TURNS TO PCPN EVOLUTION WITH WV NUMBER TWO...IE THE DEF ZN. MID LVL DRYING AND WK LRG SCALE ASCENT ACRS THE SOUTH WL LIKELY RESULT IN SOME FRZG DRZL DURING THE RMNDR OF THE NGT. WE SPECULATED HOW FAR NORTH THIS FIRST WV OF PCPN WUD GET AND IT RMND SOUTH OF STL. NOW ATTENTION TURNS TO THE IMPENDING DEF ZN. AT FIRST I WAS INCLINED TO TWEEK DWN THE AMTS IN THE STL AREA AND NORTH ...HOWEVER LKG AT LATEST RADAR TRENDS OF PCPN OVR TX...STLT...THE LATEST UA DATA AND A GLANCE AT THE NEW NGM...ETA...AND LATEST RUC I THINK NOT. WITH THE UPR SYS STILL FAR TO THE WEST IT LKS LIKE THE UPR FLOW WL BACK LATER TNGT AS IT MIGRATES TWDS US AND THIS SHUD LEAD TO DVLPMNT OF A NEW DEF ZN...I THINK ORIGINATING FM THE OLD DEF ZN OVR KS AND A NEW ONE EVOLVING FM THE PCPN FIELD OVR TX. THE NEW NGM AND ETA SUPPORT THIS SCENARIO AS DOES THE LATEST RUC. SCARY THING IS THE NGM GIVES .65 LIQ FOR STL ON TUE. THIS NEXT WV OF SN WL GRADUALLY GET ITS ACT TOGETHER OVRNGT AND SHUD START EFFECTING THE STL AND NWD AREAS WHICH HV BEEN VOID OF SN THUS FALL DURING THE DAY ON TUE. I WL UPDATE THE ZNS TO TWEEK THE WORDING A BIT AND MAY ACTUALLY HV TO BOOST THE SN TOTALS LCLY IN THE OZARKS. ELSEWHERE THE SN AMTS WL RMN THE SAME. NOW IT IS A WAITING GAME. .STL...WNTR STRM WRNG FOR MOST OF SE AND S CNTRL MO/METRO EAST AND WNTR WX ADVSRY FOR RMNDR OF METRO AREA INCLUDING STL CITY GLASS mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 255 PM EST MON DEC 23 2002 TNGT/TUE: MODELS STILL HAVE NOT COME UPON A COMMON SOLUTION REGARDING THE TIMING OF THE INCOMING PRECIP... THUS CONFIDENCE IS REDUCED. DO BELIEVE WE'LL SEE A LENGTHY PERIOD OF RAIN... AND BASED ON THE RUN-TO-RUN TRENDS OF THE MODELS... LATEST PRECIP TREND... AND THE LATEST RUC... WILL DELAY PRECIP ONSET UNTIL A FEW HOURS PRIOR TO AND SEVERAL HOURS AFTER 12Z TOMORROW. WILL HAVE THICKENING CLOUDS OVERNIGHT... BASICALLY AMOUNTING TO MOSTLY CLOUDY OR CLOUDY. CONTINUED RAINY AND COOL WORDING FOR TUESDAY. WITH CONSIDERABLY DIFFERENT H8 WIND FIELDS AND UPPER DIVERGENCE PATTERNS AMONG THE MODELS... AM VERY UNCERTAIN ABOUT QPF BUT WILL GENERALLY GO LESS THAN AN INCH FOR NOW & LET LATER SHIFTS ADJUST. LITTLE IF ANY CHANGE TO CURRENT LOWS TONIGHT... MAINLY 35 TO 40. ONLY A ONE OR TWO CATEGORY DIURNAL RISE FOR HIGHS TUE. TUE NGT/WED: EXPECT THE MOST WIDESPREAD RAIN TO TAPER OFF LATE IN THE AFTERNOON OR EARLY EVENING AS H8 WINDS DIMINISH & THE MILLER B SURFACE LOWS HEAD NE. BAGGY LOW LEVEL FLOW WILL BRING A RISK OF THE RAIN TAPERING OFF TO AREAS OF DRIZZLE THROUGH WED MORNING. EXPECT DOWNSLOPING TO KICK IN AND CLEAR OUT ANY PRECIP BY THE AFTERNOON. WILL MAKE FEW SIGNIFICANT CHANGES TO THE CURRENT LOWS/HIGHS AS THEY ARE IN LINE WITH CURRENT GUIDANCE NUMBERS. -GIH WEDNESDAY NIGHT THROUGH MONDAY: LITTLE CHANGE TO CURRENT FORECAST. NO CONFIDENCE IN ADDING RAIN 190 HOURS OUT AND WILL KEEP FORECAST DRY. WILL INDICATE SOME CLOUDS FRIDAY AND FRIDAY NIGHT AND ON MONDAY...OTHERWISE MOSTLY CLEAR WITH GENERALLY BELOW NORMAL TEMPERATURES THURSDAY FRIDAY AND NEAR TO A BIT ABOVE BEYOND. -RLH .RAH...NONE. HARTFIELD/RLH nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 925 AM EST MON DEC 23 2002 BASED ON CURRENT CONDITIONS AND THE LATEST RUC WILL UPDATE ZONES AND CHANGE TODAY/S WINDS TO LIGHT AND VARIABLE. NO OTHER CHANGES PLANNED. FCSTID = 5 CAE 64 42 54 48 / 0 50 100 50 AGS 64 43 58 48 / 0 60 100 50 SSC 64 42 55 48 / 0 50 100 50 OGB 64 43 58 48 / 0 50 100 50 .CAE... GA...NONE. SC...NONE. RJL THE FOLLOWING IS THE PREVIOUS FORECAST DISCUSSION. ************************************************************** AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 308 AM EST MON DEC 23 2002 POTENTIAL FOR SIGNIFICANT RAIN EVENT ACROSS SOUTH CAROLINA TUE. GFS SHOWING BETTER RUN-RUN CONSISTENCY THAN ETA/NGM. INTENSE UPPER LOW OVER THE SOUTHWESTERN STATES FORECAST TO MOVE EAST. PLUME OF UPPER LEVEL MOISTURE SEEN ON WATER VAPOR SPREADING NORTHEAST INTO THE PLAINS STATES. FOR TODAY ACROSS THE SOUTHEAST...JUST SOME HIGH LEVEL CI EXPECTED...INCREASING THIS AFTERNOON AS UPPER FLOW BECOMES SOUTHWEST. WILL GO MOSTLY SUNNY. CLOUDS THICKENING OVERNIGHT. WARM FRONT SETTING UP ACROSS GULF COAST REGION. 290-300K ISENTROPIC LIFT DEVELOPING AFTER MIDNIGHT. EVEN ETA MODEL SHOWING MODERATE LIFT TOWARD MORNING...ESPECIALLY IN THE CSRA. HOWEVER...LOW LEVELS WILL BE DRY EARLY AND ANY RAIN WILL BE LIGHT UNTIL DAYBREAK. WILL INCREASE POP TO LIKELY AGS AREA AND CONTINUE CHANCE REST OF CWA. STRONG UPPER LEVEL DIVERGENCE EXPECTED TUE MORNING WITH 250 MB ENTRANCE REGION OF JET ACROSS AREA. STRONG 850MB WARM AIR ADVECTION/ISENTROPIC LIFT...LOW LEVEL JET AROUND 40KT. WILL GO CATEGORICAL. MODEL QPF/HPC RATHER HIGH IN THE MIDLANDS...WILL MENTION HEAVY RAIN POSSIBLE. AVN INDICATING IN-SITU WEDGE SETTING UP...AS SURFACE LOW MOVES FROM MS TO THE CAROLINA MOUNTAINS. SECONDARY LOW DEVELOPMENT OFF THE COAST. EXPECT COOLER AIR MASS IN NORTH CAROLINA TO SPREAD SOUTH INTO MIDLANDS/CSRA. WARM FRONT JUST SOUTH OF AGS IN THE AFTERNOON...MAY TRY TO MOVE NORTH. WILL FORECAST HIGH TEMPS IN THE 50S. LOW MOVES NORTHEAST TUE NIGHT...LIFT AND MOISTURE FLUX OFF THE COAST. DRIER AIR ADVECTING INTO AREA AFTER 00Z...WITH COLD AIR ADVECTION DEVELOPING AFTER MIDNIGHT. WILL KEEP CHANCE POPS UNTIL AROUND MIDNIGHT. WED...LOOKS BREEZY AND COOL...PUT WILL DROP POPS. TEMP FORECAST...NEAR LOCAL CONSENSUS...EXCEPT COOLER TUE. FCSTID = 19 CAE 64 42 54 48 / 0 50 100 50 AGS 64 43 58 48 / 0 60 100 50 SSC 64 42 55 48 / 0 50 100 50 OGB 64 43 58 48 / 0 50 100 50 .CAE... GA...NONE. SC...NONE. AWP sc SOUTH CENTRAL TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 1103 AM CST MON DEC 23 2002 HAVE RAISED MOST TEMPS TO THE 70S RANGE AND ADJUSTED WINDS. NEXT AREA TO WATCH FOR CONVECTION APPEARS TO BE OVER THE HILL COUNTRY AROUND JUNCTION OR LEAKEY. .EWX...TOR WATCH #798 TIL 3 PM LEE LAVACA AND FAYETTE 06/08 PREVIOUS DISCUSSION... ONE OF THE MORE SIGNIFICANT TORNADO/SEVERE WEATHER THREATS OF THE YEAR FOR SOUTH CENTRAL TEXAS COMES TWO DAYS BEFORE CHRISTMAS. THE WESTERN TWO-THIRDS OF SOUTH CENTRAL TEXAS CAN EXPECT A WET MORNING WITH ISOLATED SEVERE STORMS TO CREATE A SHOPPING HAZARD. A MORE OMINOUS THREAT EXISTS EAST OF THE I-35 CORRIDOR WHERE DAYTIME HEATING WILL ENHANCE THE SEVERE WEATHER THREAT INTO A THREAT FOR SUPERCELLS AND TORNADOES. IF IT WERE NOT FOR THE MORNING STREAMER CELL SPEEDS OF AROUND 30 TO 35 MPH, WOULD BE CONCERNED OF A FLASH FLOOD THREAT. SOILS REMAIN NEARLY SATURATED FROM PREVIOUS RAINS, BUT WITH PRECIPITABLE WATER VALUES HOLDING BELOW 1.5 FOR THE MOST PART, EXPECT ONLY THREAT OF SUSTAINED HEAVY RAINS TO BE IN THE PATHS OF ANY SUPERCELLS THAT DEVELOP OVER THE SOUTHEASTERN COUNTIES LATER TODAY. WILL MENTION LOCALLY HEAVY RAINFALL FOR THE EASTERN TWO-THIRDS WITH SEVERE WORDING MENTIONED AREA-WIDE. WITH 06Z SATELLITE TRENDS SHOWING A SLIGHT EASTWARD POSITION OF THE UPPER LOW CENTER COMPARED TO FORECAST AND A PAIRED JET PATTERN INDICATING DEEPENING OVER CENTRAL TEXAS FOR THE NEXT 12 HOURS, THE QPF TRENDS WILL PROBABLY BE A BIT AHEAD OF THE ALREADY FASTER GFS. RAINFALL INTENSITIES ARE STEADILY INCREASING IN RESPONSE TO THE LOW LEVEL JET OVER THE CENTRAL COUNTIES. WITH A NEAR SOLID AREA OF RAIN EXPECTED OVER THE CENTRAL PORTIONS HALF OF THE FORECAST AREA BY AROUND DAYBREAK, WILL CALL FOR HIGH POPS OF 80 TO 100 PERCENT OVER THE EASTERN TWO-THIRDS. HELICITIES COULD APPROACH 500 M2S2 OVER THE SOUTHEASTERN COUNTIES TOWARD NOON ACCORDING TO THE RUC; WITH 1500 J/KG OR GREATER CAPES, THE THREAT FOR SEVERE WEATHER AND TORNADOES NEEDS TO BE WORDED STRONGLY HERE. FOR WESTERN SECTIONS, WILL KEEP POPS IN THE 50-60 PERCENT RANGE WITH SEVERE WORDING THROUGH THE AFTERNOON. DAYTIME HEATING COULD TRIGGER A FEW HAILSTORMS DESPITE A GOOD DRY PUNCH ENTERING WEST TX. WITH THE FASTER SPEED, WILL PLAN ON LESS MOISTURE BEING AVAILABLE WHEN THE BASE OF THE TROUGH LIFTS ACROSS THE FORECAST AREA TUESDAY. WILL TRIM POPS TO A SLIGHT CHANCE NORTHEAST. OTHERWISE A WARM AND DRY ZONAL PATTERN WILL RESUME AGAIN FOR THE NEXT SEVERAL DAYS UNTIL THE GFS AND NOGAPS DEPICT ANOTHER VIGOROUS STORM SYSTEM THREATENING THE SOUTHERN PLAINS EARLY NEXT WEEK. A WEAK SHORTWAVE MOVES THROUGH MAINLY NORTH TEXAS THURSDAY, BUT THE AIR SHOULD BE TOO DRY TO SUPPORT MEASURABLE RAINS OVER SOUTH CENTRAL TEXAS. PRELIMINARY NUMBERS... AUS 066/041/052/030/057 +5200 DRT 071/043/056/034/061 52-00 SAT 071/042/057/035/059 +4-00 .EWX...NONE. 18/3/PM tx COASTAL BEND FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 1025 AM CST MON DEC 23 2002 UPDATED THE ZONES TO REMOVE THE MENTION OF STRONG THUNDERSTORMS FOR THIS MORNING AND REMOVE MENTION OF TORNADO WATCH. TEMPERATURES AND SKY CONDITIONS ON TRACK. LOWERED POPS IN SOME AREAS...BUT KEEP THE MENTION OF SHOWERS AND THUNDERSTORMS FOR ALL BUT THE FAR WESTERN COUNTIES. LOW LEVEL MOISTURE SHOULD RAPIDLY DECREASE TODAY FROM THE WEST AS WIND VEERS AROUND TO THE SOUTHWEST IN RESPONSE TO DEVELOPING LOW JUST TO OUR NORTHWEST. SCATTERED SHOWERS AND THUNDERSTORMS STILL POSSIBLE LATER TODAY AND TONIGHT ALONG AND AHEAD OF THE FRONT. THIS WILL MAINLY BE IN THE EAST COUNTIES WHERE MOISTURE AND INSTABILITY WILL BE SUFFICIENT TO SUPPORT SHOWERS AND THUNDERSTORMS. MARINE...FOR THE UPDATE WILL BE TO KEEP WINDS SOUTH TODAY...AND NOT VEER THEM TO THE SW. BELIEVE THE AVN IS TOO COURSE WITH ITS RESOLUTION OF THE SURFACE LOW IN CENTRAL TX...AND PREFER THE MESO-ETA/RUC SOLUTION OF KEEPING SOUTH WINDS TODAY. PRESSURE GRADIENT SHOULD INCREASE AS CYCLOGENESIS TAKES PLACE IN THE HILL COUNTRY LATE MORNING/AFTERNOON AND WILL KEEP SPEEDS AS FORECAST. WILL ALSO LOWER PRECIP CHANCE OVER THE BAYS AS DYNAMICS ARE QUICKLY SHIFTING TO THE EAST. .CRP...SCA GMZ230-235-250-255-270-275. 78/92 tx SOUTH CENTRAL TEXAS FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 10 AM CST MON DEC 23 2002 SENT QUICK UPDATE TO ZONE PACKAGE FOR TORNADO WATCH # 798 WHICH REPLACES #797. MORE LATER. 06/08 ONE OF THE MORE SIGNIFICANT TORNADO/SEVERE WEATHER THREATS OF THE YEAR FOR SOUTH CENTRAL TEXAS COMES TWO DAYS BEFORE CHRISTMAS. THE WESTERN TWO-THIRDS OF SOUTH CENTRAL TEXAS CAN EXPECT A WET MORNING WITH ISOLATED SEVERE STORMS TO CREATE A SHOPPING HAZARD. A MORE OMINOUS THREAT EXISTS EAST OF THE I-35 CORRIDOR WHERE DAYTIME HEATING WILL ENHANCE THE SEVERE WEATHER THREAT INTO A THEAT FOR SUPERCELLS AND TORNADOES. IF IT WERE NOT FOR THE MORNING STREAMER CELL SPEEDS OF AROUND 30 TO 35 MPH, WOULD BE CONCERNED OF A FLASH FLOOD THREAT. SOILS REMAIN NEARLY SATURATED FROM PREVIOUS RAINS, BUT WITH PRECIPITABLE WATER VALUES HOLDING BELOW 1.5 FOR THE MOST PART, EXPECT ONLY THREAT OF SUSTAINED HEAVY RAINS TO BE IN THE PATHS OF ANY SUPERCELLS THAT DEVELOP OVER THE SOUTHEASTERN COUNTIES LATER TODAY. WILL MENTION LOCALLY HEAVY RAINFALL FOR THE EASTERN TWO-THIRDS WITH SEVERE WORDING MENTIONED AREA-WIDE. WITH 06Z SATELLITE TRENDS SHOWING A SLIGHT EASTWARD POSITION OF THE UPPER LOW CENTER COMPARED TO FORECAST AND A PAIRED JET PATTERN INDICATING DEEPENING OVER CENTRAL TEXAS FOR THE NEXT 12 HOURS, THE QPF TRENDS WILL PROBABLY BE A BIT AHEAD OF THE ALREADY FASTER GFS. RAINFALL INTENSITIES ARE STEADILY INCREASING IN RESPONSE TO THE LOW LEVEL JET OVER THE CENTRAL COUNTIES. WITH A NEAR SOLID AREA OF RAIN EXPECTED OVER THE CENTRAL PORTIONS HALF OF THE FORECAST AREA BY AROUND DAYBREAK, WILL CALL FOR HIGH POPS OF 80 TO 100 PERCENT OVER THE EASTERN TWO-THIRDS. HELICITIES COULD APPROACH 500 M2S2 OVER THE SOUTHEASTERN COUNTIES TOWARD NOON ACCORDING TO THE RUC; WITH 1500 J/KG OR GREATER CAPES, THE THREAT FOR SEVERE WEATHER AND TORNADOES NEEDS TO BE WORDED STRONGLY HERE. FOR WESTERN SECTIONS, WILL KEEP POPS IN THE 50-60 PERCENT RANGE WITH SEVERE WORDING THROUGH THE AFTERNOON. DAYTIME HEATING COULD TRIGGER A FEW HAILSTORMS DESPITE A GOOD DRY PUNCH ENTERING WEST TX. WITH THE FASTER SPEED, WILL PLAN ON LESS MOISTURE BEING AVAILABLE WHEN THE BASE OF THE TROUGH LIFTS ACROSS THE FORECAST AREA TUESDAY. WILL TRIM POPS TO A SLIGHT CHANCE NORTHEAST. OTHERWISE A WARM AND DRY ZONAL PATTERN WILL RESUME AGAIN FOR THE NEXT SEVERAL DAYS UNTIL THE GFS AND NOGAPS DEPICT ANOTHER VIGOROUS STORM SYSTEM THREATENING THE SOUTHERN PLAINS EARLY NEXT WEEK. A WEAK SHORTWAVE MOVES THROUGH MAINLY NORTH TEXAS THURSDAY, BUT THE AIR SHOULD BE TOO DRY TO SUPPORT MEASURABLE RAINS OVER SOUTH CENTRAL TEXAS. PRELIMINARY NUMBERS... AUS 066/041/052/030/057 +5200 DRT 071/043/056/034/061 52-00 SAT 071/042/057/035/059 +4-00 .EWX...NONE. 18/3/PM tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AMARILLO TX 545 AM CST MON 23 DEC 2002 PRECIPITATION HAS BROKEN OUT ACROSS THE PANHANDLES THIS MORNING AS BROAD AREA OF MID-LEVEL LIFT AND UPPER LEVEL DIFFLUENCE SPREADS OVER THE SOUTHERN PLAINS IN ADVANCE OF STRONG MID/UPPER LEVEL LOW TO THE WEST. SHORT RANGE MODELS STILL APPEAR TO BE HAVING A TOUGH TIME DEALING WITH MID/UPPER LEVEL LOW...EITHER DEPICTING A DEEP TROUGH OR A VERY WEAKLY CLOSED MID LEVEL LOW AT BEST. HOWEVER...PER ANALYSIS OF UPPER AIR DATA AND WV IMAGERY IT SEEMS THAT MID LEVEL CIRCULATION MAY BE A BIT MORE CLOSED OFF THAN MODELS ARE INDICATING. ALSO... MODELS APPEAR TO HAVE UNDERESTIMATED STRENGTH OF JET STREAK DIVING SOUTH OFF THE COAST OF SOUTHERN CALIFORNIA...WHICH WOULD SUGGEST THAT THE MID-LEVEL CIRCULATION WOULD REMAIN CLOSED A LITTLE LONGER. PRIMARY IMPACT TO THE PANHANDLES DUE TO THE ABOVE DISCREPANCIES WOULD BE REFLECTED IN INTENSITY AND DURATION OF PRECIPITATION. CONSIDERING THE AFOREMENTIONED OBSERVATIONS FORECAST PACKAGE WAS BASED TOWARDS THE TREND OF A SLIGHTLY SLOWER SOLUTION. SEVERAL HOURS OF RUC40/LAPS ANALYSIS CONTINUE TO SHOW VERY STRONG ISENTROPIC UPGLIDE AND STRONG 700-500MB DIV-Q VALUES ACROSS THE AREA WHICH IS STRONGER THAN WHAT LAST EVENINGS SHORT RANGE MODELS WERE INDICATING. ANOTHER SIGN OF A SYSTEM MORE INTENSE THAN EXPRESSED BY THE MODELS. THEREFORE...SHIFT TEAM DECIDED TO INCLUDE ALL OF THE TX/OK PANHANDLES IN A HEAVY SNOW WARNING FOR BOTH TODAY AND TONIGHT WITH UP TO 10 INCHES IN THE NE TX PANHANDLE BY TUESDAY MORNING...AND CONTINUE WITH A CHANCE OF SNOW ON TUESDAY. AFTER TUESDAY ONLY SOME MINOR CHANGES WERE MADE TO FORECAST. SHOULD BE PARTLY TO MOSTLY CLOUDY AND DRY. SNOW COVER WILL LIKELY TEMPER WARMING TREND TO A VERY GRADUAL RATE THROUGH THE WEEKEND. FCSTID = 04 AMARILLO 30 21 31 16 / 100 100 30 10 BEAVER 30 19 32 13 / 100 90 30 10 BOISE CITY 27 18 31 11 / 100 80 30 10 BORGER 32 20 31 15 / 100 100 30 10 BOYS RANCH 31 19 31 15 / 100 100 30 10 CANYON 30 21 32 16 / 100 100 30 10 CLARENDON 35 23 33 17 / 100 100 30 10 DALHART 29 18 31 14 / 100 90 30 10 GUYMON 28 18 32 13 / 100 90 30 10 HEREFORD 30 21 32 16 / 100 100 30 10 LIPSCOMB 33 20 32 15 / 100 100 40 10 SHAMROCK 36 23 33 17 / 100 100 40 10 WELLINGTON 37 24 34 18 / 100 100 40 10 .AMA... TX...HEAVY SNOW WARNING FOR TODAY AND TONIGHT TXZ001>020. OK...HEAVY SNOW WARNING FOR TODAY AND TONIGHT OKZ001>003. JH tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 845 AM CST MON DEC 23 2002 UPDATED FCST FOR N-C WI TO MENTION SNOW ACCUMULATIONS. BAND OF SNOW WITH VORT MOVG THROUGH THE AREA. RUC PROGS VORT TO SHEAR EWD...SO AMNT OF SWD MVT OF BAND IN QUESTION. MINOR ADDITIONAL CHANGES ALSO MADE TO THE REST OF THE FCST. .GRB...NONE. $$ JS/RE WWW.CRH.NOAA.GOV/GRB wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 300 AM EST TUE DEC 24 2002 FORECAST CHALLENGE -- POSSIBLE SEVERE WEATHER. --SYNOPSIS-- WATER VAPOR IMAGES SHOW UPPER JET LIFTING ACROSS TX AROUND BASE OF BROADENING UPPER TROUGH. STRONG/SEVERE CONVECTION ONGOING OVER MS/LA/ERN TX BENEATH EXIT REGION OF THIS JET. 05Z SURFACE ANALYSIS SHOWED LOW OVER LA WITH WARM FRONT AHEAD OF THIS LOW LIFTING OVER CENTRAL MS/AL/GA. OUR LOCAL BUOYS ARE REPORTING DEWPOINTS IN THE LOW/MID 60S (F) SO MOIST RETURN SHOULD CONTINUE OVER THE CWFA. A VERY IMPRESSIVE 24/00Z SOUNDING WAS TAKEN AT NEW ORLEANS WITH AN UNMODIFIED 0-3 KM SR HELICITY OF 1069 J/KG. THE TLH SOUNDING WAS NOT NEARLY SO IMPRESSIVE...BUT DID SHOW INCREASING LOWER TROPOSPHERIC FLOW AND STEEPER MID-LEVEL LAPSE RATES. --FORECAST-- MODEL PROGS ON TIMING OF FRONT AND ASSOCIATED CONVECTION REMAINS UNCHANGED FROM PREVIOUS FORECAST...SO VERY FEW CHANGES WERE MADE IN THE ZFP. MENTIONED POSSIBLE SEVERE FOR THE FIRST PERIOD DUE TO STRONG LOWER TROPOSPHERIC WIND PROFILE. AS NOTED IN LATEST SWODY1... PROGGED VERTICAL WIND FIELDS LOOKING MORE UNIDIRECTIONAL THIS AFTERNOON...AND BOUNDARY LAYER TO 6KM SHEAR IS MARKEDLY DECREASED... SO PRIMARY THREAT LOOKS LIKE DAMAGING WIND GUSTS. NONETHELESS...06Z RUC FORECAST SOUNDINGS INDICATE VERY IMPRESSIVE 30-40KT 0-1KM SHEAR OVER OUR SE AL ZONES THIS AFTERNOON...SUGGESTING BOW ECHO ASSOCIATED TORNADOES REMAIN A DISTINCT POSSIBILITY. KEPT THE SAME CARRY-OVER POPS FOR TONIGHT. FIRE WEATHER - NO HIGHLIGHTS. MARINE - ALREADY AT SCA CRITERIA OVER OUR WATERS W OF AAF. EXPECT THE SAME SHORTLY E OF AAF SO HAVE WORDED ACCORDINGLY. FEW CHANGES WERE MADE TO THE COASTAL WATERS FORECAST EXCEPT FOR SOME MINOR FIRST PERIOD ADJUSTMENTS. EXTENDED - NO CHANGES MADE. PRELIMINARY NUMBERS... TLH 073/050 056/029 +500 PFN 071/048 055/035 +300 DHN 069/044 049/030 +300 ABY 068/046 052/030 +400 VLD 072/052 056/030 +500 CTY 076/054 060/030 8600 .TLH... AL...NONE. GA...NONE. FL...SMALL CRAFT ADVISORY ALL MARINE ZONES. TJT fl AREA FORECAST DISCUSSION...MIDNIGHT FINAL NATIONAL WEATHER SERVICE LOUISVILLE KY 330 AM EST TUE DEC 24 2002 AS POTENT 250MB SUBTROPICAL JET MOVES ACROSS NRN GULF OF MEX IN CONJUNCTION WITH EWD 500MB WAVE ACROSS CEN CONUS, SFC LOW TO TRACK NEWD ACROSS TN/ERN KY INTO OH BY TUE NITE. 850MB LOW FCST TO MOVE NEWD ALONG OH RVR WITH >0C AIR FLOWING NWD INTO MOST OF LMK FA ON ERN SEMICIRCLE OF CIRC. 3Z AND 6Z RUCS ARE HINTING AT A SLOWER MVMT OF THIS LOW, ALLOWING 850MB 1C LINE TO REACH NRN TIER OF SRN IND COS BY 15Z, UNDOUBTEDLY IMPACTING PTYPE EVOLUTION. SOME INTERESTING NOTES REGARDING 0Z NWP ANALYSES: 1. PWS APPEAR TO BE TOO HIGH IN ETA/GFS OVER SRN MS RIVER VLY COMPARED TO RAOBS AND 2. 850MB TEMP ANALYSIS OF ETA SEEMS A BIT CLOSER TO REALITY, ESP WITH KLZK AND KOHX RAOBS. MESOSCALE BAND OF PCPN SET UP AROUND MIDNIGHT OVER NRN KY AND SRN IN ASSOC WITH INITIAL BAND OF 700MB DEF/FG. MIX OF RA/IP/+SN WAS FALLING FROM THIS FEATURE, WHICH IS CONSISTENT WITH RUC/ETA FCST THERMAL PROFILES. SOME REALLY BIG FLAKES FELL OUTSIDE THE OFFICE AS CONCURRENT ACARS RAOB FROM JAN-SDF FLIGHT SHOWED T PROFILE HUGGING NEG SIDE OF 0C LINE. BUT PER KY-DOT PAVEMENT DATA, TEMPS AOA 40F SHOULD HOLD DOWN ACCUMS ON PRIMARY ROAD SFCS. PER LMK-MM5 AND ETA 700MB DEF/PW FIELDS, BELIEVE THESE INITIAL BANDS SHOULD MOVE NEWD ACROSS THE FA THROUGH EARLY MORNING. WITH SOME DYNAMIC COOLING IN WEAK WAA PTTN, MORE OF A -SN/-IP MIX SHOULD BE REALIZED FROM THIS BANDING ACROSS NRN 1/2 OF FA, WITH MORE RA OVER SRN KY PER FCST RAOBS. AS SLY 850MB FLOW INCR THIS MORNING PER RUC, THINK PTYPES IN NRN PARTS OF FA SHOULD CHG TO -RA/-IP AFT SUNRISE. THIS TREND SHOWS UP WELL IN LMK-MM5 EXPERIMENTAL PTYPE CHARTS. OUT OF THIS FIRST SET OF BANDS, SOME ADDTL MINOR SN ACCUM POSS ACROSS NRN 1/2 OF FA WITHIN BANDED PCPN MAXIMA OVER NEXT COUPLE HOURS. MORE OVER TWDS BLUEGRASS REGION, SOME -FZRA POSS THRU 15Z IF 2M/PBL TEMPS REMAIN COOL ENOUGH. AS MAIN 850/700MB LOWS MOVE CLOSER TO LMK FA BY LATE MORNING/EARLY AFTERNOON, MAIN DEF/FG AXIS SHIFTS N OF FA WITH A GENERAL LULL IN THE OVERALL PCPN PICTURE. BUT THERE APPEARS TO BE A 700MB FG BAND PIVOTING AROUND IN THE VICINITY OF SRN IND, AND PCPN TAKING SHAPE OVER MO/SRN IL MAY BE ASSOC WITH THIS BAND. ALSO DURING THE COURSE OF THE AFTERNOON, SORT OF A DRY SLOT FEATURE MOVES INTO THE FA AND WITH ASSOC STEEPER L/R'S THAT COULD TURN PCPN TO MORE OF A SHOWERY MODE. DRIER AIR ALOFT WOULD ALSO ERADICATE SATURATION IN ICE CRYSTAL GEN LAYER OVER THE FA FORCING A TURN TO MORE SHALLOW CLOUD PTYPE PROCESSES WITH LIGHTER PCPN RATES. BY AFTERNOON TEMPS ACROSS KY COS WILL BE WARM ENOUGH FOR RA OR RW, BUT WITH 850MB 0C LINE REMAINING NEAR SRN IND THERE'S MORE OF A -IP/-FZRA POTL. LMK-MM5 PTYPE CHARTS SHOWING PBL RAIN WATER MVG N OF OH RIVER AFT 16Z, WHICH WOULD SUGGEST A CHG OVER TO MORE LIQUID OVER SRN IND. THEN FOR TONITE, ASSOC WITH THE LEADING EDGE OF 500MB TROF AXIS SOME WEAK LIFT IS INDICATED. COLUMN RESATURATES AND FALLS BELOW 0C FROM W-E DURING THE EVE. GFS IS SUGGESTING A WRAP-AROUND PW MAXIMA ~6Z/WED COINCIDENT WITH AREA OF POTL LIFT FROM 500MB WAVE OVER LMK FA. STATIC STABILITY IN LOW/MID TROP SEEMS A BIT STRONG, WHICH WOULD LIMIT LIFTING POTENTIAL FROM TROF PASSAGE. HWVR, LMK-MM5 PTYPE CHARTS SHOW SPOTTY AREAS OF SN CRYSTALS IN THE PBL OVER FA DURING THIS PERIOD. WILL LIKELY GO WITH HI CHC SHSN, ESP ACROSS NRN KY/SRN IN, MENTIONING ADDTL ACCUMS POSSIBLE. .SDF...WINTER STORM WARNING CANCELLED FOR NRN TIER OF SRN IND COS...AND REPLACED WITH A WINTER WX ADV THROUGH 21Z/WED. WINTER WX ADV FOR SDF/SRN IND AREA THROUGH 17Z/WED. WINTER WX ADV FOR BLUEGRASS AREA THROUGH 14Z/WED. XXV ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 346 AM EST TUE DEC 24 2002 MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE AMOUNT OF LAKE EFFECT SNOW TODAY AND TONIGHT. WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER SOUTHERN QUEBEC. ANOTHER BROADER LOW IS OVER THE CENTRAL PLAINS. A NARROW RIDGE SEPARATES THESE LOWS FROM A LONGWAVE TROUGH OVER THE NORTHERN PACIFIC. A WEAK SHORTWAVE ENERGY IS MOVING THROUGH WISCONSIN THIS MORNING. ANOTHER SHORTWAVE IS POISED OVER NORTHERN ONTARIO EXTENDING INTO SOUTHERN MANITOBA. SURFACE ANALYSIS INDICATING A BROAD RIDGE OVER NORTHERN PLAINS...AND A LOW OVER THE CANADIAN MARITIME. A WEAK RIDGE IS ALSO SHOWING UP OVER UPPER GREAT LAKES THIS MORNING. THE CENTRAL PLAINS LOW WILL BECOME MORE FOCUSED AS A CLOSED LOW DEVELOPS IN THIS LONGWAVE TROUGH OVER MID MISSISSIPPI VALLEY. THE UPPER LEVEL RIDGE WILL SHIFT INTO SOUTHERN ALBERTA TODAY. SHORTWAVE ENERGY WILL MOVE DOWN THE LEE OF THE RIDGE INTO THE FORECAST AREA THIS AFTERNOON. 850-500MB Q-VECTORS SHOWING WEAK CONVERGENCE OVER THE FORECAST AREA...MAINLY THIS MORNING. EVENING RAOBS SHOWING NEAR SATURATION BELOW 850MB AT INL AND WPL. GRB SHOWING A LITTLE DRIER BELOW 850MB. MODEL PROFILE INDICATING FAIRLY MOIST AIR MASS BELOW 850MB...AND DRY ABOVE. PRECIP WATER GENERALLY LESS .3 INCH. CONDITIONS FAVORABLE FOR SCATTERED SNOW SHOWERS TODAY. A WEAK SURFACE TROUGH WILL MOVE THROUGH LAKE SUPERIOR TODAY. 850MB TEMPERATURES WILL BE -9C OVER LAKE SUPERIOR GIVING A DELTA-T OF 12C. A FEW LAKE EFFECT SNOWS WERE OCCURRING OVER CENTRAL U.P. THIS MORNING. THIS CONDITION WILL KEEP SCATTERED SNOW SHOWERS OVER THE KEWEENAW PENINSULA AND OVER EASTERN U.P. HOWEVER...WITH MARGINAL LOW LEVEL MOISTURE AND WITH INVERSION LEVEL AROUND 3K FEET...NO SIGNIFICANT ACCUMULATION IS EXPECTED. ETA INDICATING MAINLY WEST WIND THIS MORNING. MORNING IR IMAGERY SHOWING SOME CLEARING OVER WINDWARD SIDE OF LAKE SUPERIOR. A DECK OF CLOUDS SHOWING UP OVER NORTHERN MINNESOTA THIS MORNING...IN ASSOCIATION WITH THE WEAK Q-VECTOR CONVERGENCE IN THAT AREA. RUC/ETA PROJECTING THIS Q-VECTOR CONVERGENCE TO SHIFT ACROSS THE FORECAST AREA THIS MORNING. LAKE EFFECT BANDS STILL SHOWING UP OVER THE LEE OF THE LAKE. WILL KEEP SCATTERED LAKE EFFECT SNOW IN THE FORECAST FOR THIS MORNING... BECOMING FLURRIES THIS AFTERNOON. A WEAK SHORTWAVE AND A THERMAL TROUGH WILL SLIDE ACROSS THE FORECAST AREA TONIGHT. 850MB TEMPERATURES WILL LOWER TO -10C. SURFACE-850MB RH WILL BE AROUND 90 PERCENT OVER THE AREA AS THIS TROUGH MOVES THROUGH. WIND WILL VEER NORTH OVERNIGHT. WEAK SHORTWAVE ENERGY WILL PASS THROUGH THE AREA AT THE SAME TIME. THIS WILL PRODUCE SOME LAKE EFFECT SNOWS AGAIN TONIGHT FOR THE NORTHERN COUNTIES. WARM AIR WILL ADVECT INTO THE FORECAST AREA ON CHRISTMAS DAY. SHORTWAVE ENERGY WILL SHIFT ACROSS THE AREA IN THE MORNING. CONDITIONS STILL LOOK FAVORABLE FOR SOME SCATTERED LAKE EFFECT SNOWS IN THE MORNING. A FEW FLURRIES WILL PERSIST INTO THE AFTERNOON FOR THE KEWEENAW PENINSULA AND ALONG THE LAKE OVER EASTERN U.P. IN THE AFTERNOON AS DRY AIR CONTINUES TO ADVECT INTO THE AREA. CHRISTMAS NIGHT WILL SEE THE SNOW END AND POSSIBLY SOME BREAKS IN THE CLOUD COVER. THE UPPER LEVEL AND SURFACE RIDGE WILL MOVE ACROSS THE FORECAST AREA LATE WEDNESDAY NIGHT THROUGH THURSDAY. THIS SHOULD END ANY PRECIPITATION ACROSS THE AREA. THE UPPER LEVEL RIDGE WILL SLIDE OVER THE AREA THURSDAY NIGHT. A SHORTWAVE MOVING THROUGH THIS RIDGE WILL MOVE INTO SOUTHERN MANITOBA. THE SURFACE LOW WILL MOVE INTO NORTHEAST MANITOBA DRAGGING A COLD FRONT THROUGH THE DAKOTAS INTO NORTHERN MINNESOTA...WHILE A SURFACE RIDGE MOVES INTO THE MID MISSISSIPPI VALLEY. WINDS WILL BE MAINLY OUT OF THE WEST. DELTA-T'S WILL BE AROUND 5C. DO NOT EXPECT ANY SNOW THURSDAY NIGHT. THE SHORTWAVE WILL REACH THE U.P. BY 00Z SATURDAY. THE SURFACE LOW WILL MOVE INTO WESTERN HUDSON BAY...DRAGGING THE COLD FRONT INTO THE FORECAST AREA. THE 850MB TEMPERATURE WILL AROUND -8C. THUS SNOW SHOWERS WILL BE POSSIBLE WITH ON FRIDAY. MEANWHILE AN UPPER LEVEL LOW WILL MOVE OUT OF THE CANADIAN ROCKIES INTO SASKATCHEWAN. THE SURFACE REFLECTION LOW CENTER WILL LIKEWISE MOVE INTO SOUTHERN SASKATCHEWAN PULLING A COLD FRONT INTO THE NORTHERN HIGH PLAINS. THIS WILL MOVE ACROSS THE NORTHERN PLAINS INTO THE FORECAST AREA. SHORTWAVE WILL STREAM ACROSS THE NORTHERN PLAINS. THESE WILL PRODUCE A CHANCE OF SNOW AND SNOW SHOWERS OVER THE UPPER GREAT LAKES EACH DAY THOUGH THE WEEK-END AND INTO END OF THE YEAR. .MQT...NONE. DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 330 AM CST TUE DEC 24 2002 MAIN CHALLENGE DEALS WITH DETAILING SNOW TIMING AND AMOUNTS WITH DEF ZONE TODAY. HAVE SOME CONFIDENCE WITH THIS FORECAST GIVEN DECENT AGREEMENT WITH MODEL FIELDS. REFER THE GFS SLIGHTLY BETTER FOR THIS PACKAGE GIVEN IT'S BETTER INITIALIZATION...AND IT'S 06Z VERIFICATION OF QPF/OMEGA OVER SRN PLAINS AND LWR MS VALLEY. OVERALL...WILL ONLY NEED TO TWEAK THE SNOW AMOUNTS FROM WHAT WAS ISSUED IN THE EVENING UPDATE AND WON'T CHANGE GOING WARNINGS AND ADVISORIES. SWATH OF 5 TO 11 INCHES OF SNOW OCCURRED YESTERDAY EVENING OVER CRAWFORD... WASHINGTON...ST FRANCOIS AND STE GENEVIEVE COUNTIES. AFTER A BRIEF REST AROUND MIDNIGHT...SRN COUNTIES STARTING TO SEE SNOW DEVELOP AGAIN THANKS TO A BAND OF MID-LEVEL FRONTOGENESIS DEPICTED ON RUC. RADAR MOSAIC ALSO SHOWING OUR SECOND ROUND OF SNOW CURRENTLY TAKING SHAPE OVER SWRN MISSOURI. MODELS DO SHOW DECENT LARGE SCALE ASCENT ACROSS AREA TODAY IN AREA OF Q-VECTOR CONVERGECE. AREA OF MID LEVEL CONVERGENCE WILL MOVE ACROSS NRN AND CNTRL PART OF CWA LATER THIS MORNING/AFTERNOON...WITH PERSISTENT AREA OF FRONTOGENTICAL FORCING ACROSS SRN AND ERN PARTS OF CWA. MODEL QPFS ARE NEAR OR EXCEED 1/2 INCH OF LIQUID OVER THE SERN HALF OF CWA...THOUGH ETA AND NGM TOTALS LOOK TOO HIGH. THINK THAT THIS WILL AMOUNT TO AREA OF 3-6 INCHES OF ADDITIONAL ACCUMULATION IN AREAS ALONG AND SOUTHEAST OF A CUBA TO ST CHARLES TO CARLINVILLE LINE. FORCING QUICKLY SHIFTS EWD THIS EVENING...SO CURRENT DIMINISHING TREND STILLS LOOKS GOOD. WILL USE A BLEND OF FWC/MAV TEMP GUIDANCE FOR HIGHS TODAY AND TOMORROW. WILL LEAN TOWARD COLDER MAV TEMPS TONIGHT AND GO BELOW GUIDANCE OVER SNOW COVER AREAS CHRISTMAS NIGHT WITH LIGHTER WINDS AND CLEAR SKIES. GOING EXTENDED FORECAST LOOKS REASONABLE AFTER LOOK AT LATEST MEDIUM RANGE MODELS. ANY WARMUP WILL BE HELD DOWN INITIALLY BY SNOW COVER. WHILE BEST CHANCE OF PRECIPITATON WILL WAIT UNTIL MONDAY...WIL OPT TO LEAVE CHANCE ON SUNDAY ALONE FOR NOW. .STL...WNTR STRM WRNG FOR MOST OF SE AND S CNTRL MO/METRO EAST AND WNTR WX ADVSRY FOR RMNDR OF METRO AREA INCLUDING STL CITY BRITT mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 303 AM EST TUE DEC 24 2002 ZFP: ANOTHER QUICK-HITTING AND COMPLEX STORM SYSTEM FOR THE SE STATES ON TAP TODAY. EACH OF THE MODELS OFFER UP A DIFFERENT SURFACE EVOLUTION THROUGH TONIGHT AND OVERALL CONFIDENCE IS LOW WHICH IS MORE OF A CONCERN FOR THE COASTAL WATERS FCST. WHAT IS OF BETTER CONFIDENCE IS CATEGORICAL POPS TODAY WITH NICE UPPER LEVEL DYNAMICS AND GOOD LOW LEVEL CONVERGENCE. THREAT OF SIGNIFICANT TSTMS LOOKS MINIMAL...BUT IT DEPENDS ON WHERE THE COASTAL FRONT IS THIS AFTN. WILL CONTINUE THE MENTION OF POSSIBLE TSTMS ALL ZONES TODAY. TEMPS COULD BE A REAL NIGHTMARE...WILL TREND 50-55 INLAND SOUTH CAROLINA ...55-60 COAST AND 60-65 IN SE GEORGIA. WILL MAKE A LAST MINUTE CALL ON WHETHER TO MENTION RNFL HEAVY AT TIMES TDA. RAINS SHOULD BE ENDING TONIGHT WITH DRY AIR WRAP QUICKLY RUSHING INTO THE NEGATIVELY TILTING LOW PRES TO OUR N. WED IS LOOKING MORE AND MORE LIKE A WIND ADVISORY DAY...WILL INTRO WINDY INTO THE ZONES FOR NOW. SKIES WILL BECOME MOSTLY SUNNY CHRISTMAS AFTN WITH STRONG MIXING EXPECTED. NO SIGNIFICANT WEATHER ANTICIPATED IN THE DAY 3-7 PERIODS. MAINLY BELOW CLIMO TEMPS UNTIL SOMETIME THIS WEEKEND. CWF: COORD WITH JAX/ILM THIS MORNING. GFS SOLN APPEARS TOO AGGRESSIVE WITH COASTAL LOW PRES FORMATION AROUND MIDDAY. THE LATEST RUC IS CLOSER TO THE 00Z ETA AND IS PREFERRED. PLAN TO BACK DOWN WIND AND SEAS A BIT FROM OUR PREVIOUS FCST TODAY BUT WILL RAISE SCA FOR ALL WATERS EXCEPT THE CHS HARBOR. BY MID AFTN WINDS COULD BE GUSTY NE OR LIGHT SW ALG NERN CHARLESTON COUNTY...CERTAINLY A DIFFICULT FCST. CHRISTMAS DAY WILL FEATURE STRONG WLY FLOW AND GALES WELL OFFSHORE AND STRONG SCA CONDITIONS ACROSS OUR WATERS. NOT MUCH CHANGE TO LATTER PERIODS. CHS 58 49 57 30 / 100 70 10 0 SAV 63 46 55 28 / 100 50 0 0 CHL 59 53 58 35 / 100 70 10 0 NBC 60 47 55 31 / 100 70 10 0 RBW 53 46 55 29 / 100 70 10 0 MHP 60 46 54 29 / 100 40 0 0 .CHS... GA...SMALL CRAFT ADVISORY AMZ354-374. SC...SMALL CRAFT ADVISORY AMZ350-352. 24 sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 630 AM CST TUE DEC 24 2002 UPDATE TO THE UPDATE...WINTER PRECIP IS ONCE AGAIN BREAKING OUT AND INCREASING IN COVERAGE OVER NORTHWEST AR AND NORTHEAST OK. RECENT RUNS OF THE RUC HAVE BEEN HANDLING THIS MUCH BETTER THAN THE 06Z MESOETA. WILL HOIST WINTER WEATHER ADVISORY FOR NORTHWEST COUNTIES WHERE PRECIP HAS BEGUN AS FREEZING RAIN...BUT RUC CROSS SECTIONS INDICATE A CHANGE TO ALL SNOW DURING THE MORNING. EXPECT ANOTHER ONE TO TWO INCHES BY THE TIME ITS ALL SAID AND DONE. UPDATE...CALLS TO NORTHERN COUNTIES INDICATE LIGHT RAIN FALLING. ONLY STATIONS AT OR BELOW FREEZING ARE KBPK AT 31 AND KHRO AT 30. DESPITE THE -FZRA REPORTED AT KHRO...LAW ENFORCEMENT SAYS NO PROBLEMS AT THIS TIME AND SNOW HAS MELTED OUT OF THEIR PARKING LOT. WILL LET THE WINTER STORM WARNING AND WINTER WEATHER ADVISORY EXPIRE. AS GUESSED EARLIER...STEADY RAIN EXITED SOUTHEAST ZONES ABOUT 0915Z. SO THE FLASH FLOOD WATCH WILL ALSO BE ALLOWED TO EXPIRE. AND THE NUMBERS... LIT 38 26 43 26 38 41111 HOT 38 26 44 27 39 33111 HRO 31 14 40 17 36 41111 PBF 40 27 44 27 39 33111 PREVIOUS DISCUSSION... FORECAST CHALLENGES COME IN THE FIRST TWO PERIODS. QUESTIONS INCLUDE HOW MUCH MORE RAIN IN SOUTHEAST AR...HOW MUCH MORE SNOW IN NORTH AR...WHETHER OR NOT IT WILL SNOW IN CENTRAL/SOUTH AR...AND WHEN THE CLOUDS WILL CLEAR OUT. FOR SOUTHEAST AR...THE POWERFUL STORM COMPLEX OVER LA/MS IS FINALLY TAKING ITS TOLL BY DISRUPTING THE INFLOW ABOVE THE BOUNDARY LAYER. MODELS HAVE NO CLUE ABOUT THIS...BUT THE RAPID EROSION OF THE SOUTHWEST EDGE OF THE PRECIP SHIELD IS A DEAD GIVEAWAY. EXTRAPOLATION OF BACK EDGE OF PRECIP DEPICTED ON KSHV RADAR SUGGESTS RAIN WILL END IN OUR SOUTHEAST ZONES AROUND 10Z...OR RIGHT ABOUT PRESS TIME. MORNING POPS FOR THIS AREA WILL BE A LAST MINUTE CALL. SHOULD BE ABLE TO LET FLASH FLOOD WATCH EXPIRE ALSO BUT THIS CALL IS SUBJECT TO LAST MINUTE OVERTURNING. FOR NORTH AR...DYNAMIC FORCING HAS REACHED A MAXIMUM AND SHOULD BE ON THE DECREASE OVER THE NEXT FEW HOURS. THE INFLOW DISRUPTION EFFECTS OF THE STORMS FARTHER SOUTH WILL TAKE A LITTLE LONGER TO REACH THIS AREA...BUT RADAR AND SATELLITE TRENDS SUGGEST THAT SIGNIFICANT PRECIP WILL END IN THE NORTHWEST AROUND 10Z AND PERSIST A LITTLE LONGER THAN THAT IN THE NORTHEAST. MAY BE ABLE TO LET THE WINTER STORM WARNING AND WINTER WEATHER ADVISORY EXPIRE AT 10Z...BUT WILL MAKE FINAL DECISION BASED ON RADAR TRENDS AND RESULTS OF PHONE CALLS TO AREA LAW ENFORCEMENT OFFICIALS AFTER 09Z. SNOW POTENTIAL IN CENTRAL AND SOUTH AR IS MINIMAL BUT NONZERO. NUMERICAL MODEL OUTPUT SUGGESTS A GOOD CHANCE OF SNOW THIS AFTERNOON...BUT THE AFOREMENTIONED INFLOW DISRUPTION WILL PLAY A MITIGATING ROLE. 00Z MESOETA ISENTROPIC PROGS SHOW A BRIEF PERIOD DURING THE AFTERNOON OF SHARP RISES ON THE 275-285K SURFACES WHICH SHOULD BE ENOUGH TO OFFSET DOWNGLIDE. THIS SHORT BURST OF UPWARD MOTION MAY WRING OUT A LITTLE BIT OF SNOW SINCE LOW LEVEL MOISTURE WILL STILL BE LINGERING AROUND...BUT AMOUNTS WILL BE MINIMAL. 06Z MESOETA JUST CAME IN AND IT ALSO SHOWS THE SHARP RISE MOVING FROM NORTH AR TO SOUTH AR BETWEEN 21Z AND 03Z. CLOUDS WILL CLEAR OUT WHEN LOW LEVEL THERMAL TROUGH MOVES THROUGH AND ISENTROPIC SURFACES BEGIN TO SINK RATHER THAN RISE. 00Z MESOETA SHOWED THIS OCCURRING OVERNIGHT TONIGHT. 06Z RUN IS A LITTLE SLOWER AND HINTS AT SOME STRATUS HANGING AROUND IN THE NORTHEAST THROUGH CHRISTMAS MORNING. HAVE NOT LOOKED AT TEMPS YET DUE TO FLOODING AND WINTER WEATHER CONCERNS. WILL ISSUE UPDATED AFD INCLUDING TEMPS/POPS AND ADVISORIES IF ANY AROUND 4 AM. NO CHANGES PLANNED FOR THURSDAY AND BEYOND. FOCUS IS ON THE FIRST TWO DAYS OF THIS PACKAGE. .LZK...WINTER WEATHER ADVISORY TODAY ARZ003>005-012-013. $$ 54 ar AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 955 AM EST TUE DEC 24 2002 HAV UPDATED ZONES AND COASTAL WATERS FORECASTS FOR TORNADO WATCH #806. SCA CONDITIONS UNDERWAY OVER ALL OF COASTAL WATERS. WE HAVE RECEIVED MANY REPORTS OF TORNADOES AND DAMAGE THAT WILL BE ISSUED SHORTLY IN A LOCAL STORM REPORT. .TLH... AL...NONE. GA...NONE. FL...SMALL CRAFT ADVISORY ALL MARINE ZONES. TJT PREVIOUS DISCUSSION FOLLOWS. ***************************************************************** 620 AM EST TUE DEC 24 2002 WILL BE UPDATING ZONES AND COASTAL WATERS FORECASTS FOR SHORTLY FOR TORNADO WATCH #805. LAPS ANALYSIS SHOWS INCREASING SURFACE BASED CAPE WORKING E INTO OUR WRN CWFA WHILE KEOX AND KEVX VAD WIND PROFILES ALREADY SHOW IMPRESSIVE 0-1KM SHEAR ALREADY UNDERWAY. .TLH... AL...NONE. GA...NONE. FL...SMALL CRAFT ADVISORY ALL MARINE ZONES. PREVIOUS DISCUSSION FOLLOWS. ***************************************************************** 300 AM EST TUE DEC 24 2002 FORECAST CHALLENGE -- POSSIBLE SEVERE WEATHER. --SYNOPSIS-- WATER VAPOR IMAGES SHOW UPPER JET LIFTING ACROSS TX AROUND BASE OF BROADENING UPPER TROUGH. STRONG/SEVERE CONVECTION ONGOING OVER MS/LA/ERN TX BENEATH EXIT REGION OF THIS JET. 05Z SURFACE ANALYSIS SHOWED LOW OVER LA WITH WARM FRONT AHEAD OF THIS LOW LIFTING OVER CENTRAL MS/AL/GA. OUR LOCAL BUOYS ARE REPORTING DEWPOINTS IN THE LOW/MID 60S (F) SO MOIST RETURN SHOULD CONTINUE OVER THE CWFA. A VERY IMPRESSIVE 24/00Z SOUNDING WAS TAKEN AT NEW ORLEANS WITH AN UNMODIFIED 0-3 KM SR HELICITY OF 1069 J/KG. THE TLH SOUNDING WAS NOT NEARLY SO IMPRESSIVE...BUT DID SHOW INCREASING LOWER TROPOSPHERIC FLOW AND STEEPER MID-LEVEL LAPSE RATES. --FORECAST-- MODEL PROGS ON TIMING OF FRONT AND ASSOCIATED CONVECTION REMAINS UNCHANGED FROM PREVIOUS FORECAST...SO VERY FEW CHANGES WERE MADE IN THE ZFP. MENTIONED POSSIBLE SEVERE FOR THE FIRST PERIOD DUE TO STRONG LOWER TROPOSPHERIC WIND PROFILE. AS NOTED IN LATEST SWODY1... PROGGED VERTICAL WIND FIELDS LOOKING MORE UNIDIRECTIONAL THIS AFTERNOON...AND BOUNDARY LAYER TO 6KM SHEAR IS MARKEDLY DECREASED... SO PRIMARY THREAT LOOKS LIKE DAMAGING WIND GUSTS. NONETHELESS...06Z RUC FORECAST SOUNDINGS INDICATE VERY IMPRESSIVE 30-40KT 0-1KM SHEAR OVER OUR SE AL ZONES THIS AFTERNOON...SUGGESTING BOW ECHO ASSOCIATED TORNADOES REMAIN A DISTINCT POSSIBILITY. KEPT THE SAME CARRY-OVER POPS FOR TONIGHT. FIRE WEATHER - NO HIGHLIGHTS. MARINE - ALREADY AT SCA CRITERIA OVER OUR WATERS W OF AAF. EXPECT THE SAME SHORTLY E OF AAF SO HAVE WORDED ACCORDINGLY. FEW CHANGES WERE MADE TO THE COASTAL WATERS FORECAST EXCEPT FOR SOME MINOR FIRST PERIOD ADJUSTMENTS. EXTENDED - NO CHANGES MADE. PRELIMINARY NUMBERS... TLH 073/050 056/029 +500 PFN 071/048 055/035 +300 DHN 069/044 049/030 +300 ABY 068/046 052/030 +400 VLD 072/052 056/030 +500 CTY 076/054 060/030 8600 .TLH... AL...NONE. GA...NONE. FL...SMALL CRAFT ADVISORY ALL MARINE ZONES. TJT fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 620 AM EST TUE DEC 24 2002 WILL BE UPDATING ZONES AND COASTAL WATERS FORECASTS FOR SHORTLY FOR TORNADO WATCH #805. LAPS ANALYSIS SHOWS INCREASING SURFACE BASED CAPE WORKING E INTO OUR WRN CWFA WHILE KEOX AND KEVX VAD WIND PROFILES ALREADY SHOW IMPRESSIVE 0-1KM SHEAR ALREADY UNDERWAY. .TLH... AL...NONE. GA...NONE. FL...SMALL CRAFT ADVISORY ALL MARINE ZONES. PREVIOUS DISCUSSION FOLLOWS. ***************************************************************** 300 AM EST TUE DEC 24 2002 FORECAST CHALLENGE -- POSSIBLE SEVERE WEATHER. --SYNOPSIS-- WATER VAPOR IMAGES SHOW UPPER JET LIFTING ACROSS TX AROUND BASE OF BROADENING UPPER TROUGH. STRONG/SEVERE CONVECTION ONGOING OVER MS/LA/ERN TX BENEATH EXIT REGION OF THIS JET. 05Z SURFACE ANALYSIS SHOWED LOW OVER LA WITH WARM FRONT AHEAD OF THIS LOW LIFTING OVER CENTRAL MS/AL/GA. OUR LOCAL BUOYS ARE REPORTING DEWPOINTS IN THE LOW/MID 60S (F) SO MOIST RETURN SHOULD CONTINUE OVER THE CWFA. A VERY IMPRESSIVE 24/00Z SOUNDING WAS TAKEN AT NEW ORLEANS WITH AN UNMODIFIED 0-3 KM SR HELICITY OF 1069 J/KG. THE TLH SOUNDING WAS NOT NEARLY SO IMPRESSIVE...BUT DID SHOW INCREASING LOWER TROPOSPHERIC FLOW AND STEEPER MID-LEVEL LAPSE RATES. --FORECAST-- MODEL PROGS ON TIMING OF FRONT AND ASSOCIATED CONVECTION REMAINS UNCHANGED FROM PREVIOUS FORECAST...SO VERY FEW CHANGES WERE MADE IN THE ZFP. MENTIONED POSSIBLE SEVERE FOR THE FIRST PERIOD DUE TO STRONG LOWER TROPOSPHERIC WIND PROFILE. AS NOTED IN LATEST SWODY1... PROGGED VERTICAL WIND FIELDS LOOKING MORE UNIDIRECTIONAL THIS AFTERNOON...AND BOUNDARY LAYER TO 6KM SHEAR IS MARKEDLY DECREASED... SO PRIMARY THREAT LOOKS LIKE DAMAGING WIND GUSTS. NONETHELESS...06Z RUC FORECAST SOUNDINGS INDICATE VERY IMPRESSIVE 30-40KT 0-1KM SHEAR OVER OUR SE AL ZONES THIS AFTERNOON...SUGGESTING BOW ECHO ASSOCIATED TORNADOES REMAIN A DISTINCT POSSIBILITY. KEPT THE SAME CARRY-OVER POPS FOR TONIGHT. FIRE WEATHER - NO HIGHLIGHTS. MARINE - ALREADY AT SCA CRITERIA OVER OUR WATERS W OF AAF. EXPECT THE SAME SHORTLY E OF AAF SO HAVE WORDED ACCORDINGLY. FEW CHANGES WERE MADE TO THE COASTAL WATERS FORECAST EXCEPT FOR SOME MINOR FIRST PERIOD ADJUSTMENTS. EXTENDED - NO CHANGES MADE. PRELIMINARY NUMBERS... TLH 073/050 056/029 +500 PFN 071/048 055/035 +300 DHN 069/044 049/030 +300 ABY 068/046 052/030 +400 VLD 072/052 056/030 +500 CTY 076/054 060/030 8600 .TLH... AL...NONE. GA...NONE. FL...SMALL CRAFT ADVISORY ALL MARINE ZONES. TJT fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 1000 AM CST TUE DEC 24 2002 ONGOING FORECAST IS PANNING OUT FAIRLY WELL...HOWEVER UPDATE WILL BE REQUIRED FOR PRECIP TRENDS AND TO REMOVE MORNING WORDING. 12Z RUC 700 MB OMEGA FIELDS AND MEAN RH PROGS SEEM TO HAVE A GOOD HANDLE ON THE AREA OF SNOW OVER MISSOURI AT THIS TIME. THIS SNOW IS ASSOCIATED WITH DEEPENING 500 MB SHORTWAVE OVER EASTERN KANSAS. RUC MEAN RH AND H7 OMEGA FIELDS INDICATE THIS AREA WILL MOVE NORTHEAST...WITH THE BULK OF IT STAYING NORTH OF THE OHIO RIVER THIS AFTERNOON. RUC MODEL SOUNDINGS INDICATE FREEZING RAIN OVER THE FORECAST AREA WILL CHANGE TO SNOW THIS AFTERNOON...IN LINE WITH GOING FORECAST. UPDATE WILL CONTINUE THE ADVISORY WHERE IT IS IN EFFECT...BUT WILL RAISE SNOW AMOUNTS TO 1 TO 3 INCHES FOR MUCH OF SRN ILLINOIS AND PARTS OF SE MISSOURI. THIS IS BASED ON HPC HEAVY SNOW DISCUSSION...AS WELL AS 12Z MODEL QPF GUIDANCE. .PAH...WINTER WEATHER ADVISORY FOR THIS AFTERNOON AND TONIGHT NORTHWEST OF A KPOF-KFWC LINE. WINTER WEATHER ADVISORY FOR TONIGHT FOR SOUTHWEST INDIANA...THE REMAINDER OF MO AND IL AND WEST OF A KOWB-MAYFIELD LINE IN KENTUCKY. MY ...PREVIOUS AFD... MAIN FORECAST CHALLENGE IS PRECIP TYPE/AMOUNT/TIMING WITH THE APPROACH OF THE SOUTHWESTERN U.S. UPPER LOW ANALYSIS OF THE 24/00Z UPPER AIR PLOTS REVEALED THE FOLLOWING. AT 5H A VERY BROAD TROUGH WAS CENTERED JUST WEST OF THE FOUR-CORNERS AREA WITH LOWEST HEIGHTS AROUND THE 546 DAM. BEST HEIGHT FALLS OF 60 TO 70 DAM WERE WELL UPSTREAM OF THE TROUGH ACROSS WESTERN KS INTO THE RED RIVER VALLEY AND ASSOCIATED WITH A SHORTWAVE TROUGH. THIS AREA OF BEST PRESSURE FALLS MATCHED NICELY WITH THE RIGHT ENTRANCE REGION OF A 100-110 KT 25H JET. WELL DEFINED DRY SLOT IN THE WV IMAGERY POKING INTO THIS AREA SUGGESTS A HELPFUL HAND FROM SOME POTENTIAL VORTICITY PUNCHING INTO THAT ARE. IN THE IMMEDIATE AREA OF THE CENTER OF THE FOUR-CORNERS TROUGH...ALL HEIGHT FALLS WERE UNDER 20 DAM. HOWEVER...ALONG THE CA COAST HEIGHT RISES MAXED AROUND 80 TO 90 DAM. 25H JET STRENGTH ALONG THE BACKSIDE OF THE TROUGH WAS RELATIVELY WEAK MAXING OUT AT ONLY 70-80 KTS. GIVEN THIS SET-UP ALONE...I WOULD ANTICIPATE A RATHER SLOW EJECTION OF THIS THIS TROUGH TOWARDS THE FORECAST AREA. CLOSER TO THE SURFACE...A TIGHT BAROCLINIC ZONE WAS POSITIONED ACROSS CENTRAL TX INTO NORTHWEST AR WITH A 85H LOW OVER THE ARKLATEX REGION AND A SURFACE LOW OVER WEST CENTRAL LA AT 24/03Z. ACROSS THE REGION THROUGH 03Z...PRECIPITATION HAS PRIMARILY BEEN IN THE FORM OF RAIN ACROSS MOST OF WESTERN KENTUCKY AND EXTREME SOUTHEAST MISSOURI. A VARIETY OF SNOW AND FREEZING RAIN HAS OCCURRED ELSEWHERE WITH 2 TO 4 INCHES OF SNOW THE AVERAGE ACROSS THE REMAINDER OF SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS GENERALLY SOUTH OF I-64. NORTH OF I-64 IN ILLINOIS 4 TO 7 INCHES HAS BEEN THE AVERAGE. SOUTHWEST INDIANA HAS AN AVERAGE OF 1 TO 3 INCHES. KPAH 88-D AT 05Z WAS SHOWING PRECIPITATION GRADUALLY COMING TO AN END FROM WEST TO EAST WITH THE WESTERN HALF OF SOUTHEAST MISSOURI NOW PRECIP-FREE AND THE PORTION OF SOUTHERN ILLINOIS NORTH OF I-64 PRECIP-FREE. LOOKS LIKE THE GFS/S TREND THE PAST COUPLE OF NIGHTS OF TWO DISTINCT SHOTS OF PRECIP IS COMING TO FRUITION AND AS SUCH WILL FOLLOW CLOSELY WITH ITS LATEST SOLUTION. THE 00Z RUNS OF THE GFS/ETA/NGM/CANADIAN ARE IN VERY GOOD AGREEMENT OF THE TIMING OF THE EJECTION OF THE FOUR-CORNERS TROUGH/LOW...PLACING IT OVER DODGE CITY KS BY 12Z THIS MORNING...CENTRAL ILLINOIS BY 00Z THIS THIS EVENING AND NEAR THE IN/OH STATE LINE 12Z CHRISTMAS MORNING. HOWEVER...DESPITE THIS GOOD AGREEMENT AMONG THESE FOUR MODELS...I AM A LITTLE CONCERN WITH THE SPEED OF THE EJECTION OF THE LOW GIVEN THE AFOREMENTIONED LACK OF ANY SIGNIFICANT KICKER TO DO SO. ITS A BIT HARD TO JUDGE HOW WELL THE MODELS ARE DOING CONCERNING THEIR 06Z FORECAST FOR THE POSITION OF THE LOW AS THIS IS THE ONLY TIME PERIOD WHERE THERE IS QUITE A VARIETY OF SOLUTIONS. EYEBALLING THE WV IMAGERY AT 06Z PLACES THE LOW IN NORTHWEST NM. IS THE LOW GOING TO TRAVEL FROM NORTHWEST NM TO WESTERN KS IN 6 HOURS??? 4 MODELS SAY YES...BUT HAVE MY DOUBTS. AS SUCH...I/LL STILL FOLLOW THE GFS/S TRENDS FOR TODAY...BUT SLOW FEATURES ASSOCIATED WITH THE APPROACH OF THE UPPER LOW A LITTLE BIT. BULK OF THE HEAVIEST PRECIP BY ISSUANCE TIME LOOKS TO BE CONFINED TO THE CENTRAL AND SOUTHEAST PORTIONS OF THE FORECAST AREA. THEN NEXT ROUND OF ORGANIZED PRECIP LOOKS TO RETURN TO THE NORTHWEST PART OF THE AREA AROUND MID-DAY WITH THE MAXIMA FOCUSED NORTH OF THE FORECAST AREA CLOSER TO THE I-70 CORRIDOR. AS THE MAIN UPPER TROUGH APPROACHES THE AREA THE VARIOUS CRITICAL THICKNESSES WILL BE ON THE DECREASE. COMPARING THESE IN COMBINATION WITH VARIOUS FORECAST SOUNDINGS ACROSS PARTS OF THE AREA SETS UP THE FOLLOWING PRECIP SCENARIO. FOR WESTERN SEMO AND SOUTHERN IL NORTH OF I-64 BEGIN AS FREEZING RAIN GIVEN A PROGGED LACK OF A -10C MOIST LAYER WITH SATURATED SUB-FREEZING SUPERCOOLED PROFILE FROM 700 MB TO THE SURFACE. SWITCH TO SNOW AROUND SUNSET AS ICE CRYSTAL FORMATION BECOMES MORE PROBABLE AS THE COLUMN MOISTENS ABOVE 700MB. SNOW LOOKS TO END AROUND SUNRISE CHRISTMAS. AVN QPF NUMBERS FOR THIS AREA ARE SUGGESTING 0.20 TO 0.30 TOTALS FROM MID-DAY ON WITH 0.10 TO 0.20 OF THAT DURING THE NIGHTTIME DURING THE SNOW EVENT. GIVEN THE COOLING IN THE MID LEVELS THAT IS EXPECTED...LESS THAN -10 AT 85H...WOULD ANTICIPATE ANY SNOW TO BECOME SMALLER AND SMALLER ICE CRYSTALS YIELDING A /DRY SNOW/ BY THE TIME IT ENDS. SO A 20 TO 1 SNOW/RAIN RATIO MAY BE BEST TO USE WHICH WOULD BE A ONE INCH AVERAGE OF ADDITIONAL SNOWFALL. WITH PRECIP EXPECTED TO BEGIN AS FREEZING RAIN AND AN ADDITIONAL 1 INCH OF SNOW ON TOP OF SNOW THAT EXISTS THERE NOW...A WINTER WEATHER ADVISORY FOR THIS AFTERNOON AND TONIGHT LOOKS APPROPRIATE FOR THIS AREA. FOR THE REMAINDER OF SOUTHEAST MISSOURI...THE REMAINDER OF SOUTHERN ILLINOIS SOUTHWEST INDIANA AND FAR WESTERN KENTUCKY THE AREA MAY BE HARD PRESSED TO GET MUCH OF ANY ADDITIONAL PRECIPITATION UNTIL THE LATE AFTERNOON. THEN THIS AREA LOOKS TO HAVE TEMPERATURES ABOVE FREEZING AT THIS TIME...SO ANY PRECIP LOOKS TO FALL AS RAIN AND NOT FREEZE. AFTER SUNSET THE LOWER LAYERS LOOK TO MOISTEN...BUT START OUT AS FREEZING RAIN WITH AGAIN A LACK OF A MOIST -10 C LAYER BUT THEN TRANSITION TO SNOW AS THE COLUMN MOISTENS. HOWEVER THE BEST LIFT WILL BE EAST OF THE AREA BY THEN AND ASSOCIATED QPF NUMBERS ARE 0.10 TO 0.20. SO FOR THIS AREA BY MIDNIGHT THE COLUMN HAS MOISTEN...HAS ICE CRYSTALS...BUT WITH SLIGHTLY WARMER SUB-FREEZING TEMPS. SO A RATIO CLOSER TO 10 TO 1 MIGHT BE PRUDENT IN THIS AREA...OR TOTALS UP TO TWO INCHES AFTER AN INITIAL START OF FREEZING RAIN. WILL ISSUE AN ADVISORY FOR THIS AREA AS WELL. THE HOPKINSVILLE REGION OF WESTERN KY MAY BE FINISHED WITH RAIN THE REMAINDER OF TODAY UNTIL CLOSE TO SUNSET ONCE THIS MORNING/S EPISODE ENDS. THEN THIS EVENING LIGHT PRECIP LOOKS TO DEVELOP STARTING AS LIGHT RAIN AND THEN CHANGING TO LIGHT SNOW WITHOUT A PERIOD OF FREEZING RAIN AS A MOIST -10 C LAYER DEVELOPS PRIOR TO SUB-FREEZING TEMPS AT THE SURFACE. WILL HAVE NO ADVISORIES FOR THIS AREA AND ONLY MENTION TRACE AMOUNTS OF SNOW. WITH PLENTY OF CLOUD COVER...AND SNOW COVERING PARTS OF THE AREA...AND NORTHEAST SURFACE WINDS PROVIDING COLD AIR ADVECTION...WOULD ANTICIPATE TEMPS TODAY TO REMAIN STEADY OR SLOWLY FALL. HIGHS TODAY MAY BE IN THE MORNING HOURS. TONIGHT CLOUDS DON/T LOOK TO CLEAR THE ENTIRE AREA SO SNOW COVER DOESN/T LOOK TO PLAY A ROLE IN HELPING AREAS DROP WELL BE LOW GUIDANCE NUMBERS. WITH MAV/FWC IN FAIRLY GOOD AGREEMENT...WILL GO CLOSE TO A BLEND OF THEIR NUMBERS. FOR CHRISTMAS SKIES LOOK TO CLEAR FROM WEST TO EAST. WESTERN AND NORTHERN AREAS SHOULD REALIZE LOWS BELOW GUIDANCE GIVEN THE SNOW PACK. ELSEWHERE WILL GO CLOSE TO MAV/FWC WHICH ARE SIMILAR. WEDNESDAY NIGHT LOOKS TO BE A NIGHT TO PICK UP SOME POINTS ON GUIDANCE. MOSTLY CLEAR SKIES...LIGHT WINDS AND A SNOW PACK SHOULD ALLOW WOULD SUGGEST UNDERCUTTING GUIDANCE BY AT LEAST LEAST A CATEGORY IN THESE AREAS. DENSE FOG MAY BECOME A PROBLEM THAT NIGHT OVER THE SNOW PACK. FOR NOW I/LL ONLY MENTION PATCHY FOG IN THESE AREAS. WILL CONTINUE THE TREND OF COOLER THAN GUIDANCE HIGHS WEST AND NORTH INTO THURSDAY AS WELL. THANKS SDF FOR COORDINATION/COLLABORATION. $$ DFS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 936 AM EST TUE DEC 24 2002 LATEST WATER VAPOR LOOP SUGGESTS THAT A WEAK AND SHEARED S/WV IS MOVING OVER WI AT THIS TIME...WITH IR SAT SHOWING HIGH CLDS ASSOCIATED WITH THE WAVE. MQT RADAR NOT PICKING UP ANY PCPN WITH THIS SYSTEM...BUT SPOTTERS DO REPORT SOME ZL- OVER WESTERN MQT/EASTERN ALGER ASSOCIATED WITH A WEAK CVRG AREA. SAW ALREADY HAS A WLY WIND...WITH THE RUC AND ETA SUGGESTING THAT CVRG AREA WILL WEAKEN THIS MORNING. SO WILL JUST ADDRESS THE ZL- IN NOWCASTS AS IT SHOULD DIMINISH BY LATER THIS MORNING. OTHERWISE...MAIN CONCERN FOR UPDATE IS -SHSN POTENTIAL WITH S/WV. STATIONS IN WI AND EVEN INTO THE ARROWHEAD REPORTING VERY LIGHT SNOW/FLURRIES AS THE S/WV MOVES THRU. WITH THE WINDS STAYING W-NW TODAY SEE NO REASON TO TAKE OUT MENTION OF LIGHT SNOW SHOWERS/FLURRIES TODAY. THE 06Z ETA ACTUALLY SUGGESTS THAT A WEAK CVRG BAND WILL SET UP OVER THE EAST LATER TODAY IN RESPONSE TO WLY FLOW OVER THE WEST HALF OF THE CWFA...AND N FLOW OVER THE EASTERN 1/3. DOUBT THIS WILL AMT TO ANYTHING OF MAJOR SIGNIFICANCE WITH LK-AIR DELTA-T VALUES ONLY AROUND 12C...BUT IT MAY BE ENOUGH TO DROP A HALF AN INCH OF SNOW OVER ALGER COUNTY THIS AFTN. OTHERWISE...CLD CVR LOOKS PRETTY GOOD. MOSTLY CLOUDY ALL DAY. ONLY UPDATE WILL BE TO POSSIBLY INCREASE TEMPS A LITTLE...BUT WILL HOLD OFF ON THAT UNTIL LATER TO SEE LATEST TRENDS. .MQT...NONE. MRD mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 940 AM EST TUE DEC 24 2002 RAIN HAS SPRD OVR THE CWA THIS AM. CNVCTV ACTVTY WELL S OF AREA. LTST SFC ANALYSIS SHOWG MAIN LO IN SRN GA WI SCNDRY LO FRMG IN ERN TN. WRM FNT XTNDG FRM SRN LO THRU CSTL SC...TRYG TO FRM CSTL FRNT. LTST RUC NOT DEPICTG SFC PATTERN TOO WELL BUT DOES FRM CSTL FRNT BY EARLY AFTN. IT IS ALSO SHOWG MID LVL DRYG THIS EVE. HWVR UPR LO STILL TO OUR W AND NOT XPCTD TO SWING THRU TIL TMRW AFTN. CRRNT FCST OF RAIN TDY AND TNGT WI CHC THNDR LTR TNGT AS UPR LO SWINGS THRU LUKS GUD. ONLY MINOR CHGS XPCTD TO UPDATE. MARINE: ADVISORIES ARE POSTED FOR ALL WATERS XCPT S OF CAPE LOOKOUT BUT WE'LL NOW RAISE FLAGS FOR THE SOUTHERN STRETCH ALSO SINCE SEAS WILL LIKELY MOUNT TO 6 FEET PLUS TONIGHT AS DEVELOPING LOW PRESSURE SPAWNS ALONG THE SC COAST THIS AFTN AND TRACKS NE THIS EVENING. SECONDARY AND MORE POTENT SFC LOW FORMS WED 12Z OVER THE ALBEMARLE SOUND REGION. THIS WILL BEEF UP THE SW FLOW OVER ERN NC WATERS TO NEAR GALE FORCE AS THE LOW RAPIDLY DEEPENS AND MOVES N ALONG THE DELMARVA COAST. THE BULK OF CONVECTION DURING THIS TIME WILL LIKELY BE CONFINED ALONG THE GULF STREAM WALL AS MSTR IS SWEPT OFFSHORE. WITH JUST A LITTLE MIXING CHRISTMAS DAY IS POISED TO BRING GALES AND HENCE WILL INCLUDE IN WORDING. LAND THAT SLEIGH SANTA! CGG-G/COLBY nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 915 AM EST TUE DEC 24 2002 ONLY MINOR CHANGES TO FORECAST AT 930. SNOW IS REPORTED BY SEVERAL STATIONS IN NC MOUNTAINS AND PIEDMONT. HOWEVER TEMPERATURES ARE IN THE UPPER 30S SO NO ACCUMULATION EXPECTED TODAY. NO CHANGES IN FLASH FLOOD WATCH. PRECIP ACCUMULATIONS ARE APPROACHING TWO INCHES. ONE NOTE...RADAR IS OVERESTIMATING PRECIP BY AT LEAST A FACTOR OF TWO. RUC HAS HEAVIEST PRECIP OUT OF THE AREA BY 18Z WITH ANOTHER MINOR SHOT COMING IN LATER TONIGHT. .GSP... GA...FLOOD WATCH THROUGH TONIGHT GAZ010-017>018-026-028. NC...FLOOD WATCH THROUGH TONIGHT NCZ051-058>059-062>067. SC...FLOOD WATCH THROUGH TONIGHT SCZ001>007-010. DICARLO sc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE CHARLESTON SC 746 AM EST TUE DEC 24 2002 UPDATE: ELEVATED CONVECTION QUITE EXTENSIVE AND NOT FAR FROM OUR WRN GEORGIA COUNTIES. UPDATED ZONE FORECAST TO TAKE OUT AFTERNOON THUNDER WORDING. ALSO WARM FRONT IS FURTHER INLAND THAN PREVIOUSLY ANTICIPATED AT 12Z. RAISED TEMPS AND ADJUSTED WINDS TODAY. ----------------------- PREVIOUS DISCUSSION ---------------------- ZFP: ANOTHER QUICK-HITTING AND COMPLEX STORM SYSTEM FOR THE SE STATES ON TAP TODAY. EACH OF THE MODELS OFFER UP A DIFFERENT SURFACE EVOLUTION THROUGH TONIGHT AND OVERALL CONFIDENCE IS LOW WHICH IS MORE OF A CONCERN FOR THE COASTAL WATERS FCST. WHAT IS OF BETTER CONFIDENCE IS CATEGORICAL POPS TODAY WITH NICE UPPER LEVEL DYNAMICS AND GOOD LOW LEVEL CONVERGENCE. THREAT OF SIGNIFICANT TSTMS LOOKS MINIMAL...BUT IT DEPENDS ON WHERE THE COASTAL FRONT IS THIS AFTN. WILL CONTINUE THE MENTION OF POSSIBLE TSTMS ALL ZONES TODAY. TEMPS COULD BE A REAL NIGHTMARE...WILL TREND 50-55 INLAND SOUTH CAROLINA ...55-60 COAST AND 60-65 IN SE GEORGIA. WILL MAKE A LAST MINUTE CALL ON WHETHER TO MENTION RNFL HEAVY AT TIMES TDA. RAINS SHOULD BE ENDING TONIGHT WITH DRY AIR WRAP QUICKLY RUSHING INTO THE NEGATIVELY TILTING LOW PRES TO OUR N. WED IS LOOKING MORE AND MORE LIKE A WIND ADVISORY DAY...WILL INTRO WINDY INTO THE ZONES FOR NOW. SKIES WILL BECOME MOSTLY SUNNY CHRISTMAS AFTN WITH STRONG MIXING EXPECTED. NO SIGNIFICANT WEATHER ANTICIPATED IN THE DAY 3-7 PERIODS. MAINLY BELOW CLIMO TEMPS UNTIL SOMETIME THIS WEEKEND. CWF: COORD WITH JAX/ILM THIS MORNING. GFS SOLN APPEARS TOO AGGRESSIVE WITH COASTAL LOW PRES FORMATION AROUND MIDDAY. THE LATEST RUC IS CLOSER TO THE 00Z ETA AND IS PREFERRED. PLAN TO BACK DOWN WIND AND SEAS A BIT FROM OUR PREVIOUS FCST TODAY BUT WILL RAISE SCA FOR ALL WATERS EXCEPT THE CHS HARBOR. BY MID AFTN WINDS COULD BE GUSTY NE OR LIGHT SW ALG NERN CHARLESTON COUNTY...CERTAINLY A DIFFICULT FCST. CHRISTMAS DAY WILL FEATURE STRONG WLY FLOW AND GALES WELL OFFSHORE AND STRONG SCA CONDITIONS ACROSS OUR WATERS. NOT MUCH CHANGE TO LATTER PERIODS. CHS 58 49 57 30 / 100 70 10 0 SAV 63 46 55 28 / 100 50 0 0 CHL 59 53 58 35 / 100 70 10 0 NBC 60 47 55 31 / 100 70 10 0 RBW 53 46 55 29 / 100 70 10 0 MHP 60 46 54 29 / 100 40 0 0 .CHS... GA...SMALL CRAFT ADVISORY AMZ354-374. SC...SMALL CRAFT ADVISORY AMZ350-352. 24 sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 640 AM EST TUE DEC 24 2002 BAND OF SHOWERS AND THUNDERSTORMS ACROSS CENTRAL AND NORTH GEORGIA MOVING EAST-NORTHEAST TOWARD THE SAV RIVER. SATELLITE INDICATING CLOUD TOPS COOLING. RUC AND 06Z META INDICATES POTENTIAL FOR ELEVATED CONVECTION INCREASING ACROSS THE CENTRAL AND SOUTHERN MIDLANDS. SHOWWALTER INDEX AROUND -1 IN THE CSRA. SFC-3KM SHEAR STRONG. WILL UPDATE FORECAST AND ADD ISOALTED THUNDERSTORMS TO ALL CWA EXCEPT NORTH MIDLANDS. FCSTID = 19 CAE 49 46 52 30 / 100 70 20 10 AGS 53 48 53 30 / 100 60 10 10 SSC 49 46 51 30 / 100 70 20 10 OGB 53 48 54 31 / 100 60 20 10 .CAE... GA...NONE. SC...NONE. AWP sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 1015 AM CST TUE DEC 24 2002 CURRENTLY HAVE SWATH OF LOW CLOUDS ACROSS CENTRAL AND NE SD...WITH SOME AREAS SEEING FOG AND FLURRIES. THESE CONDITIONS ARE SIMILAR TO WHAT OCCURRED ACROSS KMBG AREA AND IN ND YESTERDAY ASSOCIATED WITH AN AREA OF VORTICITY...NOW LOCATED OVER SD. LATEST RUC AND MESO-ETA SHOWING VORT MAX NEARLY STATIONARY OVER CWA THRU 00Z. 12Z KABR SOUNDING SHOWING AMOUNT OF MOISTURE DROPPING OFF SHARPLY ABOVE 925MB...AND ATMOSPHERE SATURATED BELOW THAT POINT. WITH THE VORT MAX REMAINING OVER THE AREA AND THE LOW LVL MOISTURE AVAILABLE...HAVE UPDATED MOST OF CWA TO MOSTLY CLOUDY SKIES FOR TODAY. WILL ALSO KEEP PATCHY FOG WORDING AS MOST SITES WEST OF THE HILLS REPORTING FOG WITH VISIBILITIES BETWEEN 1/2SM AND 3SM. ALSO CANNOT RULE OUT THE POSSIBILITY OF OCCASIONAL FLURRIES BEING SQUEEZED OUT OF THIS THIN LAYER OF LOW CLOUDS ACROSS THE AREA. WITH THE CLOUD COVER HAVE BUMPED MAX TEMPS DOWN A BIT ALSO. .ABR...NONE ALBRECHT sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 940 AM CST TUE DEC 24 2002 UPDATE PLANNED THIS MORNING. 15Z RUC DEPICTING H5 TROUGH EXTENDING FROM ARROWHEAD OF MN THROUGH NORTHERN IA. IR SATELLITE SHOWING HIGH CLOUDS ASSOCIATED WITH THIS FEATURE AND UPPER LOW ROTATING EAST THROUGH EASTERN KS...APPARENTLY SERVING TO PROVIDE ICE CRYSTALS TO PRE-EXISTING LOW/MID CLOUDS FOR SOME FLURRY ACTIVITY ACROSS SOME OF MY NORTHERN ZONES. THIS WILL EVENTUALLY OVERSPREAD SOUTHERN ZONES BY THIS AFTERNOON. WILL UPDATE TO ADD FLURRY MENTION. .LSE...NONE. $$ DAS wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 1030 AM CST TUE DEC 24 2002 UPDATE DISCUSSION LATEST SATELLITE...OBS AND PROFILERS SUPPORT RADAR TRENDS OF SYSTEM SPIN UP AS QUICK OR ACTUALLY A TAD QUICKER THAN 12Z MODELS WHICH LATEST 15 RUC ALSO SUGGEST. THIS WILL THROW WRAPAROUND PRECIPITATION AND DEFORMATION ZONE INTO FAR SOUTHEAST ZONES BY MID TO LATE PM PER AWIPS DISTANCE TIME FEATURE. PLAN TO UPDATE SE ZONES FOR HIGHER POPS OF LIKELY WITH MINOR SNOW ACCUMULATIONS. MAY ADD SOME FLURRIES SLIGHTLY FURTHER NORTH AS WELL. EXPECT UPDATED ZONES OUT BEFORE 11 AM CST. IA...NONE. IL...NONE. MO...NONE. NICHOLS il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 227 PM MST TUE DEC 24 2002 FORECAST CONCERNS WILL BE TEMPERATURES THROUGH THE PERIOD. SATELLITE AMPLIFIED FLOW FROM THE CENTRAL PACIFIC INTO NORTH AMERICA. SYSTEM THAT BROUGH SNOW TO SOUTHERN PORTIONS OF THE AREA IS MOVING TO THE EAST. AT JET LEVEL...IF ESTIMATES OF THE SPEEDS ARE CORRECT OUT OVER THE PACIFIC THEN THEN THE NGM IS 20 TO 30 KNOTS LOW WHILE THE ETA/AVN ARE DOING BETTER BUT STILL A TAD LOW. AT MID LEVELS...OVERALL THE MODELS WERE NOT SHARP ENOUGH WITH THE RIDGE IN THE WEST WITH THE ETA DOING BEST. THE ETA/RUC ARE DOING BETTER THROUGH SIX HOURS ON UPPER SYSTEM NOW MOVING INTO THE WYOMING. INITIALLY THE ETA LOOKED BETTER WITH HEIGHT FIELD AT 50H OVER THE CENTRAL PLAINS. HOWEVER...BY 18Z THE ETA STILL HAD EXITING UPPER LOW IN EASTERN KANSAS WHERE REST OF MODELS WERE IN CENTRAL MISSOURI. CIRCULATION LOOKS A LITTLE SOUTH OF THAT. HOWEVER...BY 00Z THE ALL THE MODELS ARE IDENTICAL WITH THE EXITING SYSTEM. AT LOW LEVELS...ETA AND AVN DID BEST WITHE ETA DOING SLIGHTLY BETTER OVER OUR AREA. EVEN THOUGH ETA IS HAVING ITS PROBLEMS INITIALLY WITH UPPER SYSTEM TO OUR EAST...WILL USE IT BASED ON A BETTER OVERALL INITIAL ANALYSIS...ESPECIALLY ON SYSTEM OVER MONTANA AND WYOMING... DOING BETTER ON CLOUD COVER AND MAXES...AND HAVING A SLIGHTLY MORE AMPLIFIED/LESS PROGRESSIVE PATTERN. MAY BLEND RUC IN FOR TONIGHT. FOR TONIGHT/CHRISTMAS DAY...WINDS WILL DIE OFF WITH LOW DEWPOINTS. WILL GO NEAR TO SLIGHTLY BELOW THE MAV WHICH DID BEST ON MINS. LOOKS LIKE THERE IS JUST ENOUGH SNOW COVER IN SOUTHERN GREELEY AND WICHITA TO SLOW DOWN THE TEMPS A LITTLE. WILL SEPARATE THEM OUT MAINLY THROUGH TOMORROW FOR SLIGHTLY COOLER TEMPS. WITH SOME DOWNSLOPE AND SUNNY SKIES PLAN ON GOING SLIGHLTY ABOVE THE MAV AND NEAR TO BELOW THE ETA MOS. FOR WEDNESDAY NIGHT/THURSDAY...STRONGER SHORTWAVE MOVES THROUGH LATE IN THE NIGHT AND EARLY IN THE DAY AS A ETA/GFS DEVELOP SOME SORT OF CUTOFF OVER EASTERN NEBRASKA. THE GFS IS STRONGER THAN THE ETA. GFS HAS DEVELOPED THESE SYSTEMS TOO STRONG RECENTLY. WITH THE WESTERLY WINDS PLAN ON GOING ABOVE THE COOLER MAV/AVN AND CLOSER TO THE ETA. FOR THURSDAY NIGHT/FRIDAY...WEAK PORTION OF JET AXIS MOVES ACROSS DURING THE NIGHT THEN AREA IS IN SUBSIDENCE DURING THE DAY. SYSTEM OVER NEBRASKA MOVES TO THE EAST AS A RESULT OF A SYSTEM MOVING ACROSS THE NORTHERN PLAINS. THEN THE UPPER RIDGE STARTS BUILDING IN DURING THE DAY. ONCE PLAN AGAIN TO WITH THE WARMER GUIDANCE SINCE MAV LOOKS TO COOL BASED ON EXPECTED CONDITIONS. FOR THE 4 TO 7 DAY PERIOD...AS OF 12Z THIS MORNING MODELS WERE NOT AMPLIFIED ENOUGH...ESPECIALLY OVER THE PACIFIC AND WESTERN PORTION OF NORTH AMERICA. THERE WERE ALSO TOO FAST/FAR EAST WITH FEATURES. THE ECMWF WAS DOING A LITTLE BETTER THAN THE 12Z GFS. THERE WERE SOME CHANGES FROM THE PREVIOUS RUN. MODELS WERE A LITTLE SLOWER AND DEEPER WITH TROF MOVING TOWARD THE WEST COAST. THE ECMWF WAS THE SLOWER OF THE MODELS. CONSIDERING THE CURRENT FLOW PATTERN AND JET WOULD THINK THAT THE ECMWF WILL DO BETTER. SATURDAY IS DRY WITH RIDGING AND THE GUIDANCE HAS COME UP DRAMATICALLY. MRF IS NOW AN OPEN WAVE WITH SYSTEM COMING ACROSS ON SUNDAY. WITH DYNAMICS COMING ACROSS WILL KEEP JUST CLOUDS IN FOR SUNDAY. ECMWF HAS SYSTEM DIGGING INTO THE DESERT SOUTHWEST...AND THEN MOVES ACROSS ON MONDAY. THIS LOOKS TOO FAST...AND PROBABLY WILL BE STILL OUT TO THE WEST. WILL KEEP MONDAY AND TUESDAY DRY WITH TROFINESS OUT TO THE WEST AND SOUTHWEST FLOW ALOFT. WILL TEND TO GO NEAR TO ABOVE GUIDANCE WITH GUIDANCE NUMBERS GETTING WARMER AND WESTERLY FLOW ALOFT. .GLD...NONE. BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 100 PM CST TUE DEC 24 2002 MAIN FORECAST CONCERN REMAINS WINTER PRECIPITATION THIS EVENING. SATELLITE AND RADAR LOOPS SHOW A WELL DEVELOPED MID LEVEL CIRCULATION CENTER SOUTH OF KSGF...ALONG THE MISSOURI/ARKANSAS BORDER AT 18Z. A BAND OF LOCALLY HEAVY SNOW IS WRAPPING NORTHWARD AHEAD OF THE SYSTEM...FROM NEAR KSGF TO KSTL AND KMDH. SPOTTER REPORTS FROM PERRY COUNTY MO INDICATED A QUICK INCH OF SNOW BETWEEN 17Z AND 18Z. MODEL QPF...MEAN RH...AND 700 MB OMEGA FIELDS APPEAR TO HAVE A GOOD HANDLE ON THE HEAVY PRECIP SHIELD. THE HEAVIEST PRECIP SHOULD MOVE EAST NORTHEAST...STAYING MAINLY NORTH OF A POPLAR BLUFF TO PADUCAH TO MADISONVILLE LINE. WHERE PRECIP HAS NOT CHANGED TO SNOW...RUC MODEL SOUNDINGS INDICATE IT WILL HAPPEN FAIRLY QUICKLY...BY 21Z AT PAH AND EVV. PRELIMINARY THINKING IS THAT AN ADVISORY WILL BE NEEDED FOR THIS EVENING ALONG AND NORTH OF A PERRYVILLE/KMDH/KOWB LINE. FINAL ADVISORY AREA WILL BE DETERMINED BASED ON RADAR AND SFC OBS AT 21Z. AT ANY RATE...THE 500 MB LOW WILL MOVE EAST OF THE FORECAST AREA AROUND 06Z...ENDING MEASURABLE SNOW CHANCES. IN THE WAKE OF THE SYSTEM...COLD ADVECTION AND AREAS OF NEW SNOW COVER WILL RESULT IN SIGNIFICANTLY COLDER TEMPS. AVN/NGM MOS GUIDANCE IS CLOSE FOR LOWS TONIGHT AND WILL BE FOLLOWED. WIND CHILLS WILL BE AROUND 10 AT KPAH BY MORNING. DESPITE CLEARING SKIES DURING THE DAY ON CHRISTMAS...HIGHS WILL BE ABOUT 10 DEGREES BELOW NORMAL GIVEN 850 TEMPS AROUND MINUS 5 OR COLDER. DRY BUT UNSEASONABLY COLD WEATHER IS EXPECTED CHRISTMAS NIGHT AND THURSDAY AS WEAK 500 MB RIDGING CROSSES THE MISSISSIPPI VALLEY. GFS/EUROPEAN SHOW ONE OR MORE CLIPPER TYPE SYSTEMS IN THE NORTHWEST FLOW THURSDAY NIGHT INTO FRIDAY NIGHT. THE TIMING AND LOCATIONS OF THESE SYSTEMS VARY GREATLY FROM MODEL TO MODEL AND RUN TO RUN. ALTHOUGH LITTLE MOISTURE WILL BE AVAILABLE TO THESE SYSTEMS...SOME LIGHT SNOW OR FLURRIES MAY OCCUR. GFS SHOWS SOME SPOTTY LIGHT QPF LATE IN THE WEEK. UNTIL MORE CONSISTENCY APPEARS IN THE MODELS TIMING OF THESE SHORTWAVES...PLAN TO LEAVE THE FORECAST DRY. A SHARP 500 MB RIDGE WILL BUILD OVER THE MISSISSIPPI VALLEY DURING THE WEEKEND...SETTING THE STAGE FOR A WARMING TREND WITH DRY CONDITIONS. OUTLOOK FOR EARLY NEXT WEEK... THE PAST COUPLE MRF RUNS INDICATE A SURFACE LOW WILL PASS NORTH AND WEST OF THE FA MONDAY...WITH SHOWERS AND MAYBE SOME CONVECTION AHEAD OF THE COLD FRONT. .PAH...WINTER WEATHER ADVISORY FOR THIS EVENING ALONG AND NORTH OF A OWB-MDH-PERRYVILLE LINE. $$ MY ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 408 PM EST TUE DEC 24 2002 THE LATEST APX 88D SHOWS A BAND OF LIGHT SNOW SHOWERS/FLURRIES OVER NORTHWEST LOWER/STRAITS REGION...PATCHY FREEZING DRIZZLE OVER EAST UPPER MICHIGAN...AND DRY OVER THE REST OF THE FORECAST AREA. THE LATEST SATELLITE TRENDS SHOW AN AREA OF CLOUDS OVER THE ENTIRE GREAT LAKES...WITH AN AREA OF DEFORMATION CLOUDS MOVING TOWARD SOUTHWEST LOWER MICHIGAN. THE LATEST SURFACE CHART SHOWS A WEAK SURFACE FRONT LOCATED ACROSS THE STRAITS AND UPPER MICHIGAN...WITH AN AREA OF HIGH PRESSURE OVER LOWER MICHIGAN AND THE WESTERN LAKES. MODEL DATA WAS IN GOOD AGREEMENT THIS RUN WITH A STORM SYSTEM MOVING OVER THE SOUTHERN OHIO VALLEY TONIGHT/WEDNESDAY...WITH SURFACE RIDGING MOVING IN THROUGH THURSDAY. THE MAIN FORECAST QUESTIONS WILL BE BASICALLY THE CHANCE AND TYPE OF PRECIPITATION THROUGH THE PERIOD. TONIGHT...THE WEAK RETURNS CURRENTLY OVER THE STRAITS AREA ARE IN RESPONSE TO A WEAK 500MB TROUGH MOVING INTO CENTRAL UPPER MICHIGAN... WITH AN ASSOCIATED VORT LOBE DROPPING INTO NORTHERN LAKE MICHIGAN. RUC MODEL SOUNDINGS SHOW LIMITED MID AND UPPER LEVEL MOISTURE OVER NORTHERN LOWER AND EAST UPPER MICHIGAN...WITH THE SURFACE BASED MOISTURE LAYER EXTENDING INTO TEMPERATURES SLIGHTLY WARMER THAN -10C. THEREFORE SNOWFALL SHOULD BE LIMITED ACROSS THE REGION TONIGHT ...IF NOT BECOMING FREEZING DRIZZLE DUE TO THE LACK OF ICE CRYSTALS WITH TEMPERATURES WARMER THAN -10C. MODEL DATA SHOWS THE UPPER TROUGH TO MOVE SLOWLY EAST/SOUTHEAST INTO THE REGION TONIGHT...WITH 700/500 QVECTORS SHOWING SOME CONVERGENCE OVER THE FORECAST AREA THIS EVENING. LAKE EFFECTS WILL ALSO BE AN INFLUENCE TONIGHT. 850MB TEMPERATURES WILL BE AROUND -10C WITH 1000/850 MB WINDS FROM THE NORTHEAST...WITH 900/700MB MOISTURE AROUND 70 PERCENT. RUC MODEL SOUNDINGS SHOW INVERSION HEIGHTS AROUND 3700 FEET TONIGHT... THEREFORE SNOW ACCUMULATIONS SHOULD BE LIMITED. WITH THE UPPER TROUGH MOVING SOUTHEAST TONIGHT AND LAKE EFFECTS...WILL MENTION FLURRIES OR LIGHT SNOW SHOWERS AND PATCHY FREEZING DRIZZLE TONIGHT. WEDNESDAY...THE SURFACE STORM SYSTEM WILL MOVE OVER SOUTHERN OHIO IN THE MORNING...MOVING ONTO THE EAST COAST DURING THE AFTERNOON. ADDITIONAL DYNAMICS OVER THE REGION WILL BE FROM AN UPPER TROUGH SLIDING SOUTHEAST OVER THE STATE...WITH A VORT LOBE MOVING SOUTHEAST OF SAGINAW BAY BY THE EVENING. AGAIN MOISTURE WILL BE LIMITED OVER EAST UPPER AND NORTHERN LOWER MICHIGAN...AND THE SURFACE BASED MOISTURE LAYER DOES NOT EXTEND INTO TEMPERATURES COLDER THAN -10C. LAKE EFFECTS WILL HAVE A CONTINUED INFLUENCE OVER THE AREA. 850MB TEMPERATURES WILL BE AROUND -10C IN THE MORNING...WARMING TO AROUND -7C DURING THE AFTERNOON. 1000/850MB WINDS WILL BE FROM THE NORTHEAST IN THE MORNING TURNING TOWARD THE NORTH BY THE AFTERNOON. MODEL SOUNDINGS SHOW INVERSION HEIGHTS TO BE AROUND 3500 FEET EARLY...WITH LIMITED MOISTURE AND INVERSION HEIGHTS DROPPING TO UNDER 3000 FEET BY THE EVENING. THEREFORE WILL MENTION A CHANCE OF SNOW SHOWERS OVER NORTHEAST LOWER DUE TO LAKE EFFECTS...AND THE STORM SYSTEM MOVING OVER THE OHIO VALLEY. THURSDAY/THURSDAY NIGHT...SURFACE RIDGING WILL BE BUILDING ACROSS THE WESTERN LAKES THURSDAY MORNING...BEFORE AFFECTING THE ENTIRE REGION BY THURSDAY AFTERNOON. ADDITIONALLY...UPPER LEVEL RIDING WILL MOVE OVER THE STATE THURSDAY...WITH MID LEVEL QVECTORS SHOWING DIVERGENCE LINGERING OVER THE STATE INTO FRIDAY. MOISTURE WILL BE LIMITED WITH 850/700 AND 700/300 MB MOISTURE DRYING TO AROUND 30 PERCENT THURSDAY MORNING...AND LINGERING INTO FRIDAY. THEREFORE WILL MENTION DRY CONDITIONS OVER THE FORECAST AREA WITH SOME SUN. FRIDAY THROUGH TUESDAY...SURFACE RIDING WILL REMAIN OVER THE EASTERN LAKES THROUGH FRIDAY...SUPPLYING SLIGHTLY ABOVE NORMAL TEMPERATURES FOR THIS TIME OF YEAR. THEN A STORM SYSTEM WILL MOVE OVER THE UPPER MIDWEST FRIDAY NIGHT...MOVING OVER THE STATE ON SATURDAY. MODELS ALSO PUSH AN UPPER TROUGH THROUGH QUICKLY BEHIND THE COLD FRONT ON SATURDAY. TEMPERATURE PROFILES WITH 850MB TEMPERATURES AROUND -4C... WOULD SUGGEST AN ALL SNOW EVENT FOR THE REGION. SLIGHTLY WARMER AIR WILL BE MOVING IN SUNDAY IN ADVANCE OF A STORM SYSTEM AGAIN MOVING OVER THE UPPER MIDWEST...WITH THE LOW CENTER RIDING AS FAR NORTH AS NORTHERN MINNESOTA. 850MB TEMPERATURES IN ADVANCE OF THIS SYSTEM WILL WARM TO BETWEEN 1C AND 3C OVER THE NORTHERN LAKES BY MONDAY. THE SYSTEM WILL MOVE EAST OF THE REGION ON TUESDAY. THEREFORE WILL MENTION A CHANCE OF SNOW ON SUNDAY IN ADVANCE OF THE SYSTEM...WITH A MIX OR RAIN/SNOW FOR LOWER MICHIGAN ON MONDAY AS THE SYSTEM NEARS. .APX...NONE. mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 200 PM EST TUE DEC 24 2002 LATEST 88D IMAGES SHOW A BAND OF SNOW IN WEAK SW FLOW ACROSS LAKE MICHIGAN. THIS IS OCCURING IN WEAK CONVERGANCE FROM NW WINDS IN WISCONSIN AND WEAK EAST WINDS ACROSS MICHIGAN. LOOKING AT THE VISIBLE SATELLITE LOOP ACROSS THE LOWER PENINSULA AN ENHANCED BAND IS MOVING NORTH AND WILL ONLY IMPACT THIS BAND FOR ANOTHER HOUR OR TWO. SO EXPECT A PERIOD OF LIGHT SNOW IN CHARLEVOIX AND EMMET COUNTIES UNDER THE BAND. ELSEWHERE EXPECT FLURRIES. THE ENHANCED AREA WILL BEGIN TO MOVE INTO EASTERN UPPER AROUND 3 PM AND BRING FLURRIES THERE SO ADDED THAT TO CURRENT ZONES AND TO TONIGHT. RUC MODEL SOUNDINGS STILL SHOW TEMPERATURES IN THE CLOUD LAY TO -10 SO NOT A GREAT AMOUNT OF INSTABILITY AND JUST ENOUGH TO KEEP FLURRIES GOING. TEMPERATURES CURRENTLY NEAR 30 AND HANDLED IN THE ZONES. .APX...NONE. HIRSCH mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 340 PM CST TUE DEC 24 2002 USING STLT TRENDS AND RUC OUTPUT FOR PINNING DOWN EXIT OF STORM ACR CWFA. S SIDE OF ENHANCEMENT PULLING NE WL TAKE HVIST SNW DURING THE EVE ACR STL METRO AREA. WL GO WITH AN ERY EVE ADVSRY FOR S IL COUNTIES AND E CNTRL AND SE COUNTIES OF MO FOR SVRL ADDL INCHES OF SNOW. FOR THE MOST PART...ACCUM TDA IN THE HVIEST SNW AREAS GENLY 4-5 INCHES SO FAR...ALTHO MESO SCALE BANDING MAY HV CERTAINLY PRODUCED GRTR AMTS. ACCUM SNWS OVR MID MO SHUD BE ENDING SHRTLY...ALTHO VSBYS IN THIS AREA HV BEEN SLO TO IMPROVE. CLRG WL SLOLY WORK ACR AREA LT TNGT AND INTO XMAS DAY...WITH CLDS LINGERING OVR E ZNS UNTIL WED NGT. FAIRLY TRANQUIL CONDS SHUD EXIST FROM CHRISTMAS DAY INTO ERY PART OF WKEND...WITH NXT CHC OF PCPN IN THE FORM OF RAIN LT SUN...AND SPCLY MON. .STL...WNTR WX ADVSRY THIS EVE FOR S IL...XTRM E CNTRL AND SE MO... INCLUDING STL METRO AREA. TRUETT mo FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 940 AM CST TUE DEC 24 2002 FORECAST CHALLENGE FOR UPDATE CONCERNS CLOUD TRENDS AND TEMPERATURES. REGION CONTINUES IN VICINITY OF 500MB TROUGH AXIS. WEAK VORTICITY MAX TRACKING SLOWLY EAST ACROSS NORTHERN SD FROM WATER VAPOR HOWEVER OTHER THAN VERY LOW AND HIGH LEVELS MOISTURE ABSENT. RED RIVER VALLEY SANDWICHED BETWEEN IFR/LIFR CIGS WTIH BR ACROSS NW MN AND CENTRAL ND. FRESH ETA SLOWLY SHIFTS CLOUD BANDS EAST IN LIGHT WESTERLY FLOW WHILE RUC HOLDS EVERYTHING IN PLACE. THERE DOES APPEAR TO BE A SLIGHT EASTWARD SHIFT. WILL WAIT FOR A FEW MORE IMAGES BEFORE DECIDING ON CLOUD ADJUSTMENTS. HOWEVER WILL NEED MORE CLOUD MENTION OVER WESTERN FA TODAY FOR SURE. WITH FRESH SNOW AND SHORTEST SOLAR PERIOD OF YEAR NOT MUCH TEMPERATURE RECOVERY EXPECTED EVEN WITH SOLAR. WITH LACK OF MIXING OR WARM ADVECTION AND ABOVE WILL NEED TO TRIM TEMPERATURES A NOTCH OR SO OVER MOST AREAS. .FGF...NONE. VOELKER nd AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 343 PM CST TUE DEC 24 2002 ANYTHING OF MAJOR SIGNIFICANCE APPEARS TO BE MISSING FROM MOST OF THIS FORECAST...ONLY PERHAPS IN THE EXTENDED. WK SFC RIDGE OVR ERN PART OF DKTS AND NEBRASKA...BUT OVERALL WK SFC GRADIENT. WIDSPREAD BAND OF LOW CLOUDS BACKED UP AGAINST RIDGE AXIS IN WKLY CONVERGENT LOW LEVEL FLOW. FOG PRETTY MUCH BY THE WAYSIDE NOW... AND ONLY A FEW FLURRIES REMAIN WITH LOW DBZ RETURNS AT KABR WANING. PROBLEM TONIGHT WITH LOWS IS THE CLOUDS...WHICH WILL BE PARAMOUNT TO TEMPERATURE AND TRENDS. EROSION OCCURRING FROM BOTH SIDES...MOST SO ON W. LACK OF PROPAGATION TO E RESULT OF HEATING...AND MORE NLY LOW LVL TRAJECTORY. MDLS DID HORRID JOB INITIALIZING AND NOT A GREAT DEAL OF HELP...COMPARE LACK OF MSTR AND MUCH WKR CAPPING IN KABR SOUNDING VS RUC/ETA INITIALIZATION. CLOUDS SHOULD SLOW DISSIPATION THIS EVENING WITH LESS MSTR FALLOUT FM FLURRIES...AND LOSS OF MIXING. MAY EVEN SEE SOME DEGREE OF REFORMING BLO STRONG INVERSION OVERNIGHT. HOWEVER...CONVERGENCE AXIS BECOMING LESS DEFINED WITH TIME OVERNIGHT...SO LOOK FOR WHATEVER IS LEFT TO UNDERGO RAPID DISSIPATION ON CHRISTMAS. OTHER CLDS ROTATING INTO ERN CWA WITH BACK EDGE OF SWRD SINKING SHEAR AXIS...AND WL BRUSH THRU WITH A FEW FLURRIES BEFORE DISSIPATING LTR TONIGHT AS WELL. LITTLE ELSE OF IMPORTANCE TO OCCUR THROUGH FRIDAY NIGHT WITH TMPS MAIN CONCERN. ELEVATION IN WK FLOW WL BE MORE OF AN EFFECT ON LOWS. WARMER AIR INITIALLY COMING IN FM NW ALFT. FAIRLY DECENT CDFNT FORCED BY SHARP TROUGH DIGGING INTO MN ON MONDAY. DYNAMICS/MSTR TOO SPARSE FOR PCPN MENTION...BUT MAY GET JUST A FEW SC ACRS FAR NE AT BEST. DESPITE RETURN OF COOLER AIR FRIDAY...WL BE MUCH BETTER MIXED DAY AND WL MENTION BREEZY/WINDY...WITH TMPS WARMEST IN SHORT TERM. IN THE EXTENDED RANGE...VOLATILITY OF MDLS CONTINUE WITH STRENGTH OF PAC FLOW. THIS IS NOT ANY BETTER SHOWN BY 3 CONSECTIVE RUNS OF GFS STARTING 18Z YESTERDAY...WHICH WENT FROM COLD AND DRY SUNDAY NIGHT...TO A SIGNIFICANT WINTER STORM FOR ERN SD...TO EXTREMELY MILD AHEAD OF A FRONT. ENSEMBLES NOT A LOT OF HELP AND DEPICT UNCERTAINTY AS WELL...WITH SIG STD DEVIATIONS IN EPAC AND GRTLKS. TREND HAS BEEN FOR MOST MDLS TO GO SLOWER WITH PROGRESSION DUE TO DIGGING ENERGY W...AND MORE DEVELOPMENT DOWNSTREAM WITH FRIDAY DIGGING TROUGH. THIS WL RETARD WARMUP A BIT ON SAT IN THE EAST WITH SFC RIDGE OVER THE AREA EARLY IN THE DAY...AND S TO SE COMP OF LOW LVL FLOW LATER ON WITH WAA ALFT. GRADIENT STRENGTHENS SAT NIGHT AND ELEVATION LOWS SEEM IN ORDER. SUNDAY LOOKS TO BE MILDEST DAY AHEAD OF FRONTAL ZONE IN WRN PLAINS LTR AFTN. WL KEEP TMPS ABOUT 5-10 DEGREES SHY OF RECORDS...AND NERVOUS WITH PROBABILITY OF SW FLOW ALFT CI. WL ADD IN THREAT FOR SNOW LTR SUNDAY NIGHT AND MONDAY SWEEPING THRU CWA WITH FAIR DYNAMICS EVEN WITH STGR NRN STREAM...BUT UNLESS THINGS CHANGE AGAIN CONSIDERABLY...SHOULD NOT BE A BIG DEAL. WL TREND MUCH COOLER WITH FAIR NUMBER OF ENSEMBLE MEMBERS MORE AMPLIFIED TO E EARLY IN WK...BUT STILL NORMAL OR ABR FOR MON/TUE. .FSD...NONE CHAPMAN sd