AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 910 PM EST THU DEC 23 2004 ...CLOUDY/WET/COLD THROUGH CHRISTMAS DAY... .DISCUSSION... COLD FRONT IS MAKING SLOW BUT STEADY PROGRESS THRU THE FL PENINSULA THIS EVENING. AT 01Z...THE WINDSHIFT LINE EXTENDED FROM VENICE TO ST. AUGUSTINE. EVENING TEMPS/DEWPOINTS ARE STILL IN THE M60S/L70S...WITH THE CRUX OF THE COLD AIR BEGINNING TO FILTER DOWN FROM THE CENTRAL PANHANDLE: SFC DEWPOINTS AT VALDOSTA HAVE FALLEN 16F DEG SINCE 20Z. MASSIVE SUBSIDENCE INVERSION BUILDING INTO THE AREA BEHIND THE FRONT...THE 00Z KTAE SOUNDING SHOWS A 25C DEG INVERSION IN THE H95-H80 LYR WHILE THE RUC40 ANALYSIS INDICATES H85-H70 LYR RH AS LOW AS 5%. DENSE STRATUS DECK PUSHING SE AS WELL...MANY SITES REPORTING CIGS AOB 1500FT. MIN TEMPS IN THE AFTN PACKAGE SEEM A LITTLE BIT LOW CONSIDERING THE EVENING TEMPS...BUT PROBABLY NOT MORE THAN A SINGLE CAT. WITH THE COLD AIR THAT'S PUSHING INTO THE NRN PENINSULA...AM LOATHE TO START TWEAKING THE AFTN PACKAGE...ESPECIALLY CONSIDERING ANY CHANGES WOULD BE LARGELY TRANSPARENT. NO UPDATES PLANNED THIS EVENING. && .MARINE... S/SWRLY FLOW CONTINUES AT 10-15KTS AS THE FRONT PUSHES TOWARD THE AREA. SEAS IN THE 3-5FT RANGE...BUT THE OFFSHORE COMPONENT IS GENERATING VERY CHOPPY CONDITIONS WITH AVG WV PDS BLO 5SEC...WILL MENTION "CHOPPY" CONDITIONS FOR THE OPEN ATLC WATERS. WINDS/SEAS ARE NOT EXPECTED TO KICK UP TO CAUTIONARY LVLS UNTIL FRIDAY WHEN THE HIGH PRESSURE RIDGE BEGINS TO BUILD ACROSS THE STATE IN ERNEST. NO SIG CHANGES ANTICIPATED. && .MLB WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT-TERM...LASCODY LONG-TERM....BRAGAW fl AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE GOODLAND KS 536 PM MST THU DEC 23 2004 .DISCUSSION...TEMPERATURES IN SOME WESTERN LOCATIONS HAVE ALREADY DROPPED BELOW MIN FORECASTS. SO HAD TO LOWER MINS THERE AND ADJUST HOURLY TRENDS ON TEMPERATURES AND DEWPOINTS AS WELL. WIND FIELD NON- EXISTENT RIGHT NOW. WILL UPDATE WITH REALITY AND RUC AT THIS TIME. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...WIND CHILL ADVISORY TONIGHT UNTIL 8 AM MST FRIDAY ALL ZONES. NE...WIND CHILL ADVISORY TONIGHT UNTIL 8 AM MST FRIDAY ALL ZONES. CO...WIND CHILL ADVISORY TONIGHT UNTIL 8 AM MST FRIDAY ALL ZONES. && $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 255 PM CST THU DEC 23 2004 .DISCUSSION... DAYS 1-2... THE MAIN FORECAST DECISION IS WHEN WILL THE SNOW END (HOW SOON) AND LOW TEMPERATURES TONIGHT. THE RUC40 AND ETA12 MIGRATE THE SNOW FIELD SOUTHWESTWARD AND CLEAR ALL SNOW FROM OUR CWA BY 03Z. THE OTHER MODELS QUICKLY MOVE THE MEASURABLE SNOW FROM SW KANSAS INTO THE OKLA/TX PANHANDLE BETWEEN 00 AND 06Z. PLAN TO KEEP A 30 POP IN MORTON, STEVENS, AND SEWARD COUNTIES TIL 04Z, AND 20 POPS ACROSS THE REST OF THE WESTERN 2/3RDS THROUGH 03Z. LITTLE IN THE WAY OF ADDITIONAL ACCUMULATION EXPECTED AFTER 00Z. BTW, THE WINTER WEATHER ADVISORY IN THE WEST 10 COUNTIES WILL EXPIRE AT 6 PM CST, AND THE PLAN IS TO LET IT DIE. AFTER THE SNOW MOVES OUT, EXPECT A RATHER QUICK CLEARING OUT OF CLOUDS FROM THE NORTHEAST TO THE SOUTHWEST. THIS SHOULD ALLOW THE WEAK WIND FIELD TO DECOUPLE AND WINDS TO GO LIGHT FOR A 4-6 HOUR PERIOD, BEFORE SHIFTING TO LIGHT SW BY MORNING. WITH CLEAR SKIES AND LIGHT WINDS, ALONG WITH DRY DEW POINTS, THINK THE LOWS TONIGHT WILL BOTTOM OUT. RAISED LOWS ACROSS THE SOUTHERN HALF JUST A NOTCH, THINKING THE CLOUDS THERE WILL TAKE THE LONGEST TO CLEAR OUT, AND THE SOUTHWEST FLOW WILL RETURN THERE THE SOONEST. WILL HAVE TO WAIT AND SEE JUST HOW COLD IT GETS, AND HOW THE NEW SNOW FIELD PLAYS A PART. THE OTHER THING TO NOTE IS WIND CHILL INDICES. EVEN WITH LIGHT WINDS UNDER 7 KTS, TEMPS THIS COLD YIELD WIND CHILLS IN THE -15 TO 19F RANGE BETWEEN 08Z AND 14Z. WILL ADD MENTION OF WIND CHILLS TO THE NORTHERN TIER OF ZONES, IF NOT GENERATED BY IFPS. FOR NOW, WILL HOLD OFF ON A WIND CHILL ADVISORY SINCE WIND SPEED WILL BE LESS THAN 10 KTS. AS FOR FRIDAY, PLAN TO WARM MAX TEMPS UP UNDER MOSTLY SUNNY SKIES AND SW FLOW, UP AROUND 30-32F MOST PLACES, EXCEPT SW WHERE 3-4 INCHES OF SNOW FELL. THIS TEMP PATTERN WILL HOLD TRUE THROUGH CHRISTMAS, AS THE SNOW BANDS WILL PLAY A PART IN DAY TIME HEATING AND DIURNAL COOLING. BEST MODEL APPEARS TO BE THE ETA, WHICH INITIALIZED BEST AT 5H AND SURFACE AT 12Z. CLOSE BEHIND WAS THE NGM, BUT NGM SEEMS TOO WARM CONSIDERING THE CURRENT COLD AIR MASS OVER MUCH OF THE MID SECTION OF THE COUNTRY. DAYS 3-7... THE MAIN CHANGE TO THE FORECAST WAS TO BUMP TEMPERATURES UP IN THE LATTER PERIODS OF THE EXTENDED FORECAST MID-NEXT WEEK...AS IT NOW APPEARS THE GFS IS TRENDING TOWARD THE CONSISTENT ECMWF SOLUTION OF KEEPING THE INITIAL TROUGH ESSENTIALLY CUT-OFF FROM THE MAIN POLAR WESTERLIES NEXT WEEK. THIS WILL KEEP THE PLAINS IN A GENERAL SOUTHWEST FLOW REGIME WHICH MEANS DRY AND MILD. ANY COLD AIR INTRUSION WILL HAVE TO WAIT UNTIL THE EJECTION OF THAT CUT-OFF LOW...WHICH WILL PROBABLY HAPPEN IN TIME...AS A DEEPER, KICKER SYSTEM DIVES SOUTH-SOUTHEAST FROM THE FAR NORTHEAST PACIFIC/GULF OF ALASKA REGION. THERE'S PRETTY MUCH NO SKILL, HOWEVER, IN DETERMINING WHEN THIS IS EXACTLY GOING TO HAPPEN TEN DAYS OUT. THE THREE-DAY MEAN 500MB CHART FROM THE ECWMF VALID 8-10 DAYS SUGGESTS THE MEAN TROUGH AXIS WILL COME INTO THE WESTERN CONUS...AND THE MAKINGS OF ANOTHER COLD EPISODE COULD BE POSSIBLE WITH LARGE POSITIVE HEIGHT ANOMALIES/RIDGE AXIS NOSING INTO THE ARCTIC REGIONS NORTH OF THE BEARING STRAIT. THE EXPERIMENTAL CDC REFORECAST MODEL ALSO SHOWS THIS SORT OF SIGNAL, BUT NOT AS PRONOUNCED IN THE ENSEMBLE MEANS. THE NEXT COLD EPISODE MAY NOT OCCUR UNTIL AFTER THE 8-10 DAY PERIOD...AND GIVEN THIS UNCERTAINTY, WILL STAY WITH A NEAR/NEAR 8-10 DAY OUTLOOK. && .PRELIMINARY POINT TEMPS/POPS... DDC 02 29 18 51 / 20 00 00 00 GCK 00 30 17 50 / 20 00 00 00 EHA 06 32 16 48 / 30 00 00 00 LBL 04 30 18 48 / 30 00 00 00 HYS -1 29 22 52 / 00 00 00 00 P28 01 27 19 51 / 20 00 00 00 && .DDC WATCHES/WARNINGS/ADVISORIES... KS...NONE. && $$ 12/25 ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1050 PM EST THU DEC 23 2004 .AVIATION... CHALLENGE OF FORECAST WILL CONTINUE TO BE THE DEGREE OF LAKE EFFECT SNOW SHOWER ACTIVITY THAT CAN STREAM OVER FROM SOUTHWEST LOWER MI. TRENDS IN KGRR/KDTX 88DS HAVE SHOW ROGUE ELEMENTS BREAKING OFF MAIN BANDS AND SLIPPING INTO SOUTHERN CWA. SO FAR...DTW HAS SEEN LITTLE MORE THAN SCATTER MVFR CLOUDS...BUT ARB HAS RECEIVED SOME LIGHT SNOW SHOWER ACTIVITY WITH THE CEILING BELOW 2KFT IN THE PAST FEW HOURS. OVERALL TREND IN MAIN LAKE EFFECT AREA HAS CHANGED VERY LITTLE... PERHAPS JUST HINTING AT A SLIGHTLY MORE WESTWARD PUSH AS ACTIVITY IS PENETRATING TO KFPK AND LOOKS TO BRUSH LAN/TEW IN THE NEXT FEW HOURS. SEE NO REASON WHY THIS TREND WON/T CONTINUE AND WILL HOLD THE CURRENT FORECAST OF INCREASING THIS ACTIVITY ACROSS THE CWA OVERNIGHT AND HOLDING IT TO ONE DEGREE OR ANOTHER THROUGH FRIDAY...BEFORE A MORE SOUTHERLY FLOW FRIDAY EVENING INTO THE OVERNIGHT HOURS BREAKS THIS CONNECTION TO SE LOWER MI DOWN. && .UPDATE...ISSUED AT 850 PM EST. ONLY PART OF FORECAST THAT SEEMS TO NEED UPDATING TONIGHT WILL BE LOW TEMPERATURES...PARTICULARLY OVER INTERIOR PORTIONS OF THE THUMB REGION...SAY ALONG/EAST OF I 75 AND ALONG/NORTH OF I 69 OR PERHAPS EVEN THE M 59 CORRIDOR. 18Z ETA AND NEW 00Z RUC KEEP WEST WINDS AT 5 KNOTS OR SO OVERNIGHT...AND THIS IS ALREADY COMING TO FRUITION THIS EVENING. WITH FRESH 6-10 INCH SNOWPACK IN PLACE...THIS ARGUES FOR VERY LOW TEMPERATURES TONIGHT AS COLDER AIR CONTINUES TO SEEP EAST INTO THE AREA...THIS ALL ASSUMING THAT SKIES REMAIN RELATIVELY CLEAR FOR PART OF THE NIGHT. THIS IS THE TRICK AS LAKE EFFECT SNOW SHOWERS AND CLOUDS IN GENERAL WILL GRADUALLY MAKE GREATER INROADS INTO THE CWA AS THE LOW LEVEL FLOW SHIFTS FROM WNW TO W TO WSW OVERNIGHT...IN ADDITION TO THE LAKE EFFECT ACTIVITY BECOMING BETTER ORGANIZED ANYWAY. AM NOT AS CONCERNED ABOUT THE SOUTHERN CWA AS SCT/BKN CLOUDS...WITH A PASSING SNOW SHOWER OR TWO...ARE ALREADY IN PLACE TO HELP INSULATE AND REDUCE RADIATIVE COOLING. AS OF 830 PM...ANOTHER NICELY ORGANIZED BAND IS ALSO TRYING TO SHIFT INTO THE "AREA OF CONCERN" FROM NORTHERN LOWER MICHIGAN. WOULD EXPECT THE WHOLE IDEA OF INCREASING CLOUDS TO BE THE RULE OVER THE ENTIRE CWA AFTER MIDNIGHT...SO WON/T GO WITH PLUMMETING OVERNIGHT TEMPERATURES (ALTHOUGH ANY AREA WITH CLEAR SKIES WOULD DO JUST THAT) JUST PLAN ON SHAVING A FEW MORE DEGREES OFF IN AREAS THAT WILL REMAIN RELATIVELY CLEAR FOR THE FIRST HALF OF THE NIGHT. TOUGH CALL ON HOW LOW TO GO. WILL WATCH CLOSELY AND UPDATE AGAIN IF THE TEMPERATURES TAKE OFF DOWNWARD LATER THIS EVENING. && .SHORT TERM...ISSUED AT 331 PM EST. BITTER COLD TEMPERATURES THROUGH CHRISTMAS DAY. TROUGH AXIS TO PULL INTO THE WESTERN GREAT LAKES REGION TONIGHT...RESULTING IN 850 MB TEMPS DROPPING INTO THE LOWER 20S(C) OVER LAKE MICHIGAN. LOW LEVEL WINDS WILL CONTINUE TO SLOWLY DECREASE OVER SOUTHEAST MICHIGAN THROUGH THE EVENING HOURS AS THE GRADIENT SLACKENS. WITH THE WINDS DECREASING AND SURFACE VISIBILITIES IMPROVING OVER THE EASTERN THUMB...WILL CANCEL BLIZZARD WARNING EARLY. AS WINDS CONTINUE TO BACK TO THE WEST THIS EVENING/TONIGHT...LAKE EFFECT SNOW SHOWERS OFF OF LAKE MICHIGAN SHOULD REALLY BEGIN TO MOVE INTO SOUTHEAST MICHIGAN BY MORNING. WITH THE FRESH SNOW PACK...WILL CONTINUE WITH THE CURRENT MIN FORECAST TONIGHT...5 TO 10 DEGREES...A DEGREE OR TWO BELOW GUIDANCE. 12Z MESOETA IMPLYING SOME TYPE OF I-94 BAND TRYING TO SET UP BY 12Z FRIDAY...BASED ON 1000 TO 850 MB OMEGA/WIND FIELDS (ALTHOUGH WEAK). WITH HIGH RH INDICATED AT 925 AND 850 MB...HAVE BUMPED POPS UP TOMORROW BY 10 PERCENT. IT LOOKS LIKE WHATEVER I-94 BAND THAT TRIES TO DEVELOP WILL ADVANCE NORTH DURING THE DAY...INTO THE M-59 CORRIDOR. THIS OSCILLATION SHOULD KEEP ANY ACCUMULATIONS LIGHT. NONE-THE-LESS...WITH A VERY HIGH SNOW TO LIQUID RATIO...WILL CARRY 1 TO 2 INCHES IN THE ZONES. WOULD NOT EXPECT MUCH OF A RISE IN TEMPERATURES TOMORROW BASED ON THE HEART OF THE ARCTIC AIRMASS BEING OVER SOUTHERN LOWER MICHIGAN (1000 TO 500 MB THICKNESSES AROUND 500 DAM). HOWEVER...WOULD THINK THE INFLUENCE OF THE WARM WATERS OF LAKE MICHIGAN WILL BE GOOD FOR A 5 DEGREE RISE. && .LONG TERM...ISSUED AT 331 PM EST. FOR FRIDAY NIGHT INTO WEEKEND...WEAK RIDGE TRAVERSES SOUTHERN MI FRIDAY NIGHT...THEN THE MODEL CHOICES BEGIN. THE ETA...SUPPORTED BY CANADIAN AND UKMET...BRINGS DEFINITIVE WAVE SOUTHEAST ACROSS THE AREA SATURDAY THROUGH SATURDAY NIGHT...TO DELAY ONSET OF ANY REAL WARMING/RETURN FLOW...WHILE GFS AMONG OTHER MODELS JUST INDICATES LINGERING TROUGHINESS OVER NORTHERN LAKES REGION. GIVEN GROWING MODEL CONSENSUS TOWARD ETA IDEA...WILL GO THAT ROUTE. AT 500 MB...TO GO ALONG WITH THIS...THE PREFERRED ETA AND OTHER MODELS...AFTER THE OVERALL HIGH AMPLITUDE TROUGH MOVES EAST...INDICATE A RECARVING OF TROUGHING INTO LAKES REGION AS SHORTWAVE TROUGH PIVOTS DOWN FROM THE NORTH...WITH PLAINS RIDGE MEANWHILE BUILDING UP. DEEPER MOISTURE INCREASES FRIDAY NIGHT..THEN GOOD SATURDAY AND SATURDAY NIGHT ACCOMPANYING LOW...THEN SHARP DRYING SUNDAY BEHIND THIS WAVE AS PER ETA. LOW LEVEL MOISTURE...HOWEVER...WILL BE MORE PLENTIFUL...WITH SOME DEGREE OF LAKE EFFECT FOR CHANCE SNOW SHOWERS BEHIND LOW FOR SUNDAY. FRIGID AIR THAT POURS BACK IN FRIDAY WILL BE SLOW TO BE DISPLACED...ESPECIALLY GIVEN THE PREFERRED ETA WEEKEND SYNOPTIC FEATURES. 850 TO 500 MB QVECTOR CONVERGENCE WILL INCREASE LATE FRIDAY NIGHT...BUT BE RATHER GOOD FOR SATURDAY INTO SATURDAY NIGHT. CURRENT TEMPERATURE FORECASTS CLOSELY FOLLOWED...EXCEPT INTEND TO RAISE TEMPERATURES SUBSTANTIALLY SATURDAY NIGHT AHEAD OF INCOMING WAVE...LITTLE OR NO DROP OFF OVERNIGHT. FOR NEXT WEEK THROUGH THURSDAY PERIOD...MODELS EXHIBIT QUITE A VARIETY OF DETAIL DIFFERENCES...THOUGH THEY DO AGREE ON A PATTERN CHANGE TO A WARMER REGIME. AT 500 MB...LOTS OF DETAIL DIFFERENCES WITH WESTERN AND CENTRAL STATES TROUGH/RIDGE FEATURES...GENERALLY PREFER ECMWF IDEA OF AGAIN SHOWING MORE PERSISTENT RIDGING OVER PLAINS...BUT EVEN ECMWF DOES DENT THIS RIDGE WITH SHORTWAVE TROUGH IMPULSE TUESDAY. AT THE SURFACE...WARMER FLOW INDICATED IN GENERAL...THOUGH PLENTY OF MODEL TO MODEL TIMING DIFFERENCES...BOTH AS TO SETTING UP OF STRONGER WARM RETURN FLOW AND SUBSEQUENT PASSAGE OF WEAK TROUGHING. SOME SEMBLANCE OF CONSENSUS AS TO PASSAGE OF WEAK TROUGH/FRONT PASSAGE ABOUT TUESDAY...PLUS INCREASING MOISTURE ABOUT THURSDAY AS LOW MOVES UP INTO WESTERN LAKES REGION. WILL MENTION CHANCE POPS OF LIGHT RAIN OR SNOW TUESDAY...AND CHANCE RAIN SHOWERS THURSDAY. WILL KEEP CLOSE TO CURRENT FORECAST TEMPERATURES FOR NEXT WEEK...NOT BUYING INTO THE HIGH GUIDANCE TEMPERATURES YET...ESPECIALLY GIVEN THE DEEP SNOW COVER TO MELT...NOT ONLY OVERHEAD BUT IN STATES SOUTH OF MI AS WELL. && .DTX WATCHES/WARNINGS/ADVISORIES... .MI...NONE. .LAKE HURON...NONE. .LAKE ST CLAIR...NONE. .MI WATERS OF LAKE ERIE...NONE. && $$ GURNEY/SF/DWD mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 853 PM EST THU DEC 23 2004 .DISCUSSION... LAKE EFFECT SNOW CONTINUES THIS EVENING AND HAVE SEVERAL HEADLINES TO WORRY ABOUT. QUICK LOOK AT SFC OBS SHOWS THE WINDS ON LAND ARE WEST AND THE ETA AND RUC ARE NOT SHOWING THIS AND HAVE THE WINDS MORE NW THAN WHAT IS ACTUALLY OCCURRING. BOTH MODELS DID THE SAME THING LAST NIGHT. WITH THE WEST WINDS ON LAND...THIS HAS ACTUALLY PUSHED THE LAKE EFFECT SNOW BANDS FURTHER EAST EVEN WITH THE NW WINDS. KMQT RADAR SHOWING A MAIN LAKE EFFECT SNOW BAND THAT WAS IN EASTERN MQT COUNTY EARLIER HAS NOW BEEN PUSHED BY THIS LAND BREEZE EAST INTO ALGER COUNTY. CALLS TO GOGEBIC COUNTY INDICATED THAT THERE IS NO HEAVY SNOW OCCURRING. WITH THIS IN MIND...WILL BE CANCELLING THE LAKE EFFECT SNOW WARNING EARLY FOR GOGEBIC COUNTY AND WILL ALSO CANCEL THE LAKE EFFECT SNOW ADVISORY EARLY FOR MARQUETTE COUNTY. WILL BE WORKING ON THE WSW PRODUCT SHORTLY TO HAVE IT OUT BY 10 PM AND WILL ALSO BE UPDATING THE ZONES SHORTLY TOO. GOING FORECAST OTHERWISE HAS THINGS WELL IN HAND. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING UNTIL 11 PM EST FRIDAY MIZ001-003. LAKE EFFECT SNOW WARNING UNTIL 11 AM EST FRIDAY MIZ006. LAKE EFFECT SNOW WARNING UNTIL 6 AM EST FRIDAY MIZ002. LAKE EFFECT SNOW ADVISORY UNTIL 6 AM EST FRIDAY MIZ085. && $$ MICHELS mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 850 PM EST THU DEC 23 2004 .UPDATE... ONLY PART OF FORECAST THAT SEEMS TO NEED UPDATING TONIGHT WILL BE LOW TEMPERATURES...PARTICULARLY OVER INTERIOR PORTIONS OF THE THUMB REGION...SAY ALONG/EAST OF I 75 AND ALONG/NORTH OF I 69 OR PERHAPS EVEN THE M 59 CORRIDOR. 18Z ETA AND NEW 00Z RUC KEEP WEST WINDS AT 5 KNOTS OR SO OVERNIGHT...AND THIS IS ALREADY COMING TO FRUITION THIS EVENING. WITH FRESH 6-10 INCH SNOWPACK IN PLACE...THIS ARGUES FOR VERY LOW TEMPERATURES TONIGHT AS COLDER AIR CONTINUES TO SEEP EAST INTO THE AREA...THIS ALL ASSUMING THAT SKIES REMAIN RELATIVELY CLEAR FOR PART OF THE NIGHT. THIS IS THE TRICK AS LAKE EFFECT SNOW SHOWERS AND CLOUDS IN GENERAL WILL GRADUALLY MAKE GREATER INROADS INTO THE CWA AS THE LOW LEVEL FLOW SHIFTS FROM WNW TO W TO WSW OVERNIGHT...IN ADDITION TO THE LAKE EFFECT ACTIVITY BECOMING BETTER ORGANIZED ANYWAY. AM NOT AS CONCERNED ABOUT THE SOUTHERN CWA AS SCT/BKN CLOUDS...WITH A PASSING SNOW SHOWER OR TWO...ARE ALREADY IN PLACE TO HELP INSULATE AND REDUCE RADIATIVE COOLING. AS OF 830 PM...ANOTHER NICELY ORGANIZED BAND IS ALSO TRYING TO SHIFT INTO THE "AREA OF CONCERN" FROM NORTHERN LOWER MICHIGAN. WOULD EXPECT THE WHOLE IDEA OF INCREASING CLOUDS TO BE THE RULE OVER THE ENTIRE CWA AFTER MIDNIGHT...SO WON/T GO WITH PLUMMETING OVERNIGHT TEMPERATURES (ALTHOUGH ANY AREA WITH CLEAR SKIES WOULD DO JUST THAT) JUST PLAN ON SHAVING A FEW MORE DEGREES OFF IN AREAS THAT WILL REMAIN RELATIVELY CLEAR FOR THE FIRST HALF OF THE NIGHT. TOUGH CALL ON HOW LOW TO GO. WILL WATCH CLOSELY AND UPDATE AGAIN IF THE TEMPERATURES TAKE OFF DOWNWARD LATER THIS EVENING. && .AVIATION...ISSUED AT 555 PM EST. VRF CONDITIONS SHOULD BE MORE OF THE RULE TO START THIS FORECAST PERIOD. MVFR CONDITIONS ASSOCIATED WITH SYNOPTIC SCALE TROF ARE SLIDING EAST OF THE TAF SITES AS WE SPEAK. THAT WILL LEAVE THE OCCASIONAL LAKE EFFECT SNOW SHOWER THAT WILL TRY TO SWEEP IN FROM WESTERN LOWER MICHIGAN...BRINGING MARGINAL MVFR CEILINGS/VSBYS THIS EVENING INTO THE OVERNIGHT PERIOD. GRR 88D SHOWS THE ACTIVITY TO BE FAIRLY DISORGANIZED ATTM. HOWEVER...A FEW DECENT STREAMERS ARE SETTING UP FROM TIME TO TIME AND MAKING A RUN AT DTW/DET. THEY JUST CAN/T QUITE SURVIVE THE DOWNSLOPE AFTER REACHING THE "HIGHLAND" WEST OF THE TAF SITES. FLOW BACKS TO THE WEST AND EVENTUALLY WEST/SOUTHWEST LATE TONIGHT THROUGH FRIDAY AROUND THE BASE OF UPPER LOW THAT SINKS INTO THE NORTHERN LAKES...LEADING TO A BETTER CHANCE OF ORGANIZED BANDS OF SNOW TO MOVE INTO THE AREA. 18Z ETA SOUNDING FROM THE LAKE MICHIGAN SHORELINE NEAR BIV INDICATES THE EQUILIBRIUM LEVEL TO ONLY EDGE DOWN FROM 8KFT THIS EVENING TO A GENERAL 7KFT ON FRIDAY...WITH 100-200 J/KG OF CAPE HOLDING STRONG UNDER THE INVERSION AS COLD CORE OF AIR WORKS INTO THE AREA. WILL CONTINUE THE PREVIOUS FORECAST TAFS WITH THE IDEA OF MORE PREVALENT SNOW SHOWERS HEADING INTO FRIDAY AND CONTINUING THROUGH THE DAY. THESE WILL BRING MVFR CONDITIONS MORE OFTEN THAN NOT THROUGH THE DAY. && .SHORT TERM...ISSUED AT 331 PM EST. BITTER COLD TEMPERATURES THROUGH CHRISTMAS DAY. TROUGH AXIS TO PULL INTO THE WESTERN GREAT LAKES REGION TONIGHT...RESULTING IN 850 MB TEMPS DROPPING INTO THE LOWER 20S(C) OVER LAKE MICHIGAN. LOW LEVEL WINDS WILL CONTINUE TO SLOWLY DECREASE OVER SOUTHEAST MICHIGAN THROUGH THE EVENING HOURS AS THE GRADIENT SLACKENS. WITH THE WINDS DECREASING AND SURFACE VISIBILITIES IMPROVING OVER THE EASTERN THUMB...WILL CANCEL BLIZZARD WARNING EARLY. AS WINDS CONTINUE TO BACK TO THE WEST THIS EVENING/TONIGHT...LAKE EFFECT SNOW SHOWERS OFF OF LAKE MICHIGAN SHOULD REALLY BEGIN TO MOVE INTO SOUTHEAST MICHIGAN BY MORNING. WITH THE FRESH SNOW PACK...WILL CONTINUE WITH THE CURRENT MIN FORECAST TONIGHT...5 TO 10 DEGREES...A DEGREE OR TWO BELOW GUIDANCE. 12Z MESOETA IMPLYING SOME TYPE OF I-94 BAND TRYING TO SET UP BY 12Z FRIDAY...BASED ON 1000 TO 850 MB OMEGA/WIND FIELDS (ALTHOUGH WEAK). WITH HIGH RH INDICATED AT 925 AND 850 MB...HAVE BUMPED POPS UP TOMORROW BY 10 PERCENT. IT LOOKS LIKE WHATEVER I-94 BAND THAT TRIES TO DEVELOP WILL ADVANCE NORTH DURING THE DAY...INTO THE M-59 CORRIDOR. THIS OSCILLATION SHOULD KEEP ANY ACCUMULATIONS LIGHT. NONE-THE-LESS...WITH A VERY HIGH SNOW TO LIQUID RATIO...WILL CARRY 1 TO 2 INCHES IN THE ZONES. WOULD NOT EXPECT MUCH OF A RISE IN TEMPERATURES TOMORROW BASED ON THE HEART OF THE ARCTIC AIRMASS BEING OVER SOUTHERN LOWER MICHIGAN (1000 TO 500 MB THICKNESSES AROUND 500 DAM). HOWEVER...WOULD THINK THE INFLUENCE OF THE WARM WATERS OF LAKE MICHIGAN WILL BE GOOD FOR A 5 DEGREE RISE. && .LONG TERM...ISSUED AT 331 PM EST. FOR FRIDAY NIGHT INTO WEEKEND...WEAK RIDGE TRAVERSES SOUTHERN MI FRIDAY NIGHT...THEN THE MODEL CHOICES BEGIN. THE ETA...SUPPORTED BY CANADIAN AND UKMET...BRINGS DEFINITIVE WAVE SOUTHEAST ACROSS THE AREA SATURDAY THROUGH SATURDAY NIGHT...TO DELAY ONSET OF ANY REAL WARMING/RETURN FLOW...WHILE GFS AMONG OTHER MODELS JUST INDICATES LINGERING TROUGHINESS OVER NORTHERN LAKES REGION. GIVEN GROWING MODEL CONSENSUS TOWARD ETA IDEA...WILL GO THAT ROUTE. AT 500 MB...TO GO ALONG WITH THIS...THE PREFERRED ETA AND OTHER MODELS...AFTER THE OVERALL HIGH AMPLITUDE TROUGH MOVES EAST...INDICATE A RECARVING OF TROUGHING INTO LAKES REGION AS SHORTWAVE TROUGH PIVOTS DOWN FROM THE NORTH...WITH PLAINS RIDGE MEANWHILE BUILDING UP. DEEPER MOISTURE INCREASES FRIDAY NIGHT..THEN GOOD SATURDAY AND SATURDAY NIGHT ACCOMPANYING LOW...THEN SHARP DRYING SUNDAY BEHIND THIS WAVE AS PER ETA. LOW LEVEL MOISTURE...HOWEVER...WILL BE MORE PLENTIFUL...WITH SOME DEGREE OF LAKE EFFECT FOR CHANCE SNOW SHOWERS BEHIND LOW FOR SUNDAY. FRIGID AIR THAT POURS BACK IN FRIDAY WILL BE SLOW TO BE DISPLACED...ESPECIALLY GIVEN THE PREFERRED ETA WEEKEND SYNOPTIC FEATURES. 850 TO 500 MB QVECTOR CONVERGENCE WILL INCREASE LATE FRIDAY NIGHT...BUT BE RATHER GOOD FOR SATURDAY INTO SATURDAY NIGHT. CURRENT TEMPERATURE FORECASTS CLOSELY FOLLOWED...EXCEPT INTEND TO RAISE TEMPERATURES SUBSTANTIALLY SATURDAY NIGHT AHEAD OF INCOMING WAVE...LITTLE OR NO DROP OFF OVERNIGHT. FOR NEXT WEEK THROUGH THURSDAY PERIOD...MODELS EXHIBIT QUITE A VARIETY OF DETAIL DIFFERENCES...THOUGH THEY DO AGREE ON A PATTERN CHANGE TO A WARMER REGIME. AT 500 MB...LOTS OF DETAIL DIFFERENCES WITH WESTERN AND CENTRAL STATES TROUGH/RIDGE FEATURES...GENERALLY PREFER ECMWF IDEA OF AGAIN SHOWING MORE PERSISTENT RIDGING OVER PLAINS...BUT EVEN ECMWF DOES DENT THIS RIDGE WITH SHORTWAVE TROUGH IMPULSE TUESDAY. AT THE SURFACE...WARMER FLOW INDICATED IN GENERAL...THOUGH PLENTY OF MODEL TO MODEL TIMING DIFFERENCES...BOTH AS TO SETTING UP OF STRONGER WARM RETURN FLOW AND SUBSEQUENT PASSAGE OF WEAK TROUGHING. SOME SEMBLANCE OF CONSENSUS AS TO PASSAGE OF WEAK TROUGH/FRONT PASSAGE ABOUT TUESDAY...PLUS INCREASING MOISTURE ABOUT THURSDAY AS LOW MOVES UP INTO WESTERN LAKES REGION. WILL MENTION CHANCE POPS OF LIGHT RAIN OR SNOW TUESDAY...AND CHANCE RAIN SHOWERS THURSDAY. WILL KEEP CLOSE TO CURRENT FORECAST TEMPERATURES FOR NEXT WEEK...NOT BUYING INTO THE HIGH GUIDANCE TEMPERATURES YET...ESPECIALLY GIVEN THE DEEP SNOW COVER TO MELT...NOT ONLY OVERHEAD BUT IN STATES SOUTH OF MI AS WELL. && .DTX WATCHES/WARNINGS/ADVISORIES... .MI...NONE. .LAKE HURON...SMALL CRAFT ADVISORY FOR ALL NEARSHORE WATERS EARLY THIS EVENING. .LAKE ST CLAIR...SMALL CRAFT ADVISORY FOR EARLY THIS EVENING. .MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY FOR EARLY THIS EVENING. && $$ SF/DWD mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 315 PM EST THU DEC 23 2004 .DISCUSSION... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A DEEP UPR TROF OVER CNTRL NAMERICA WITH H5 TEMPS AOB -40C AS FAR S AS NEBRASKA. FA IN CYC NLY FLOW BTWN ARCTIC HI PRES NR LK WINNIPEG AND POWERHOUSE SFC LO MOVING INTO THE NE US...AND COLD FLOW (H85 TEMPS IN THE -20C TO -25C RANGE) CAUSING NMRS LES BANDS PRIMARILY INTO THE WRN U.P. AND BTWN MQT AND MUNISING. LO TEMPS THIS MRNG CLOSE TO SFC HI -20F TO -40F. SHRTWV NOTED MOVING INTO NW WI AND ASSOCIATED DPVA/H85-5 QVECTOR CNVGC APPEARS TO BE ENHANCING ACTIVITY THIS AFTN. DLH 88D DEPICTED LES BAND COMING ONSHORE NR IWD...WITH REFLECTIVITY UP TO 10K FT. IWD CONSISTENTLY REPORTING VSBY NR 1/2SM THIS MRNG INTO THE AFTN. 12Z INL SDNG IS DRY ABV SHALLOW ARCTIC AIR...BUT TRAJECTORIES APPEAR TO BE COMING MORE FM YPL...WHERE 12Z SDNG DEPICTS HI RH UP TO H65. ANOTHER SHRTWV MOVING INTO NRN MANITOBA THIS MRNG ACCOMPANIED BY MID CLD/SOME -SN. MAIN FCST CONCERNS THIS PACKAGE ARE LES TRENDS/ACCUMS/GOING HEADLINES AND POTENTIAL NEED FOR WIND CHILL ADVY OVER THE INLAND ZNS. FOR TNGT...MODELS SHOW SHRTWV OVER NRN MANITOBA DROPPING TOWARD LK SUP BY 12Z FRI...WITH DPVA/H85-5 QVECTOR CNVGC/12HR FCST H5 HGT FALLS ARPCHG 100M ACCOMPANYING THIS FEATURE. ALTHOUGH SFC DWPTS ARE QUITE LO WITHIN THE ARCTIC AIRMASS...THE HI RH SHOWN ON THE YPL SDNG AND THE DYNAMICS ACCOMPANYING THE SHRTWV SUG POTENTIAL FOR SGNFT LES DESPITE LO TEMPS THAT MIGHT OTRW LIMIT DENDRITIC SN GROWTH. AS DEEPER SFC LO TO THE E CONTINUES TO MOVE NE INTO SE CAN OVERNGT... MODELS SHOW PRES GRADIENT LOOSENING UP AND VORTEX DVLPG OVER ERN LK SUP IN RESPONSE TO LATENT HEATING FM THE RELATIVELY WARM LK WATERS AND WEAKER SYNOPTIC WINDS. USED FINER RESOLUTION ETA RUNS FOR FCST DETAILS AS LARGER SCALE MODELS IN AGREEMENT VORTEX WL DVLP. WITH APRCH OF MANITOBA SHRTWV AND VORTEX DVLPMNT...LARGER SCALE LLVL WINDS BACK STRONGLY TO A MORE WNW DIRECTION DURING THE NGT. FINER RESOLUTION ETA WINDS SHOW SHARP H95 CNVGC IN ERN MQT/WRN ALGER AND OVER GOGEBIC/ONTONAGON THIS EVNG SHIFTING INTO NRN CMX COUNTY AND ERN ALGER COUNTY BY 12Z FRI IN RESPONSE TO THESE DVLPMNTS AND DVLPG LAND BREEZE/INTRUDING SHALLOW ARCTIC AIR. HAVE OPTED TO CONT MQT ADVY INTO THIS EVNG AND UPGRADE WATCHES OVER KEWEENAW COUNTIES AND ALGER TO A LK EFFECT SN WRNG. SINCE BETTER CNVGC WL SHIFT TO THE N... WL GO WITH ONLY A MINIMAL ADVY FOR NRN SCHOOLCRAFT COUNTY TNGT. GOING FCST FOR LES TO DIMINISH OVER GOGEBIC COUNTY OVERNGT APPEARS ON TARGET GIVEN THIS FCST AS WELL. TREND FOR BACKING WINDS FCST TO CONTINUE ON FRI AS SHRTWV FCST TO MOVE E OF ANJ...WITH RISING HGTS/DNVA IN ITS WAKE DURING THE AFTN. FINER RESOLUTION ETA RUNS SHOW AXIS OF SHARP CNVGC BTWN LAND BREEZE FLOW AND MORE NLY COMPONENT OVER LK SUP MAINTAINED BY PERSISTENT VORTEX OVER ERN LK SUP EDGING SLOWLY N DURING THE DAY TOWARD KEWEENAW COUNTY AND COASTAL ALGER COUNTY ARND GRM. WL LEAVE WRNG FOR ONTONAGON COUNTY EXPIRE AS SCHEDULED FRI MRNG AND CONT WRNGS FOR KEWEENAW ZNS THE ENTIRE DAY AND OVER ALGER COUNTY TO THE AFTN. TENDED TOWARD LO END OF MOS GUIDANCE FOR LO TEMPS TNGT/HI TEMPS FRI IN AREAS NOT EXPERIENCING LK SUP MODIFICATION GIVEN SHALLOW NATURE OF INCOMING COLD AIRMASS AND OBSVD LO TEMPS THIS MRNG UPSTREAM. MANY PLACES OVER THE W HALF OF CWA MAY NOT SEE TMAX GET ABV ZERO ON FRI. WIND CHILLS TNGT INTO EARLY FRI OVER INLAND AREAS WL DEPEND ON WHETHER SUSTAINED WIND SPEEDS WL EXCEED 10 MPH. GFS/ETA/NGM MOS SHOW PREDOMINANT SFC WINDS DECREASING TO UNDER 10 MPH DURING THIS TIME...SO EVEN THOUGH AN OCNL WIND SPEED OVER 10 MPH MAY CAUSE THE WIND CHILL TO FALL TO ADVY/WRNG CRITERIA...WL NOT HEADLINE ATTM. WITH RISING HGTS FCST TO CONT FRI NGT...CORE OF DEEP COLD AIR PROGGED TO DRIFT SLOWLY TO THE N WITH BACKING LARGER SCALE WNDS TO MORE WSW OVERNGT. THINK THIS TREND WL PUSH ERN LK SUP VORTEX/BETTER H95 CNVGC FAR ENUF N TO END LES DURING THE NGT. KEWEENAW COUNTY IS FCST TO REMAIN WITHIN AXIS OF SHARPER CNVGC UNTIL ALMOST 06Z...SO HAVE EXTENDED WRNG THRU FRI EVNG FOR THE KEWEENAW ZNS. MEANWHILE... LARGER SCALE ISENTROPIC LIFT IS FCST TO COMMENCE ON THE 280K ISENTROPIC SFC (ARND H7)...SO EXPECT AN INCRS IN MID/HI CLD DURING THE NGT THAT WL TEND TO PUT A BRAKE ON HOW FAR TEMPS CAN FALL. HOWEVER...STILL LOOKING AT BRUTALLY COLD READINGS WITH DAYTIME TEMPS SO LOW. THE LOWEST TEMPS PROBABLY WL BE CLOSER TO LOWER GFS MOS GUIDANCE (PROBABLY LOWER THAN THAT AT AREAS WHICH DECOUPLE) AND REACHED RELATIVELY EARLY BEFORE THE ARRIVAL OF WAD CLD. WIND SPEEDS SHOULD BE LGT ENUF TO PRECLUDE ANY WIND CHILL CONCERNS AS MODELS HINT AT A SFC RDG AXIS ARRIVING IN THE EVNG. GENERAL ISENTROPIC LIFT FCST TO CONT ON SAT AS CORE OF COLD AIR CONTINUES TO LIFT SLOWLY NE. HOWEVER...BOTH GFS/ETA SHOW A WEAK SHRTWV/SFC LO RACING SE AND ACRS WI IN THE AFTN. SINCE SYS WL BE QUITE MSTR STARVED...SEEMS LIKE BEST OPPORTUNITY FOR ANY -SN WL BE OVER THE ERN ZNS DOWNWIND OF LK MI. WL CARRY A CHC OF -SN NEAR THE SW BORDER AND DOWNWIND OF LK MI IN THE MRNG...THEN ACRS THE ENTIRE AREA DURING THE AFTN WITH SOMEWHAT HIER POPS DOWNWIND OF LK MI. RIGHT NOW IT APPEARS THE LLVL WINDS WL HAVE SO MUCH OF A WLY COMPONENT THAT THE BETTER CHC OF LK ENHANCEMENT OFF LK MI WL BE INTO MACKINAC COUNTY. TEMPS WL STILL BE WELL BLO NORMAL DESPITE THE WAD WITH H85 TEMPS FCST ARND -17C. WL TEND TOWARD THE LO END OF MOS GUIDANCE FOR TMAX. SOME TROUBLING TRENDS ON THE LATEST RUNS FOR SAT NGT/SUN AS ETA AND ESPECIALLY UKMET AS THESE MODELS SHOW CLIPPER LO WHICH STREAKS THRU WI INTENSIFYING TO THE E WITH MORE CYC LLVL NE FLOW OVER THE FA SAT NGT/SUN. 12Z GFS ENSEMBLE MEAN GUIDANCE ALSO HINTS AT THIS TREND EVEN THOUGH OPERATIONAL RUN IS MUCH WEAKER THAN THE ETA/UKMET. HAVE OPTED TO MAINTAIN GOING SN CHCS ON SAT NGT/SUN TO REFLECT THE POTENTIAL FOR THIS CLIPPER SYS BRINGING A MORE SUSTAINED PD OF -SN. WL LOWER TEMPS TO REFLECT A MORE NLY WIND COMPONENT AND LESS LARGE SCALE WRMG. EXTENDED MODEL GUIDANCE CONTINUES TO POINT TOWARD A MODIFICATION OF THE ARCTIC CHILL NEXT WEEK WITH A TREND TOWARD A DEEPENING TROF IN THE W AND A BLDG RDG IN THE E. UNFORTUNATELY...THE DETAILS APPEAR QUITE MUDDLED ATTM AS FAR AS THE TIMING OF INDIVIDUAL SHRTWVS AND PCPN EPISODES IN THE WAD REGIME IN ADVANCE OF THESE SYSTEMS. SO RIGHT NOW...WL TEND TOWARD A COMBINATION OF NCEP MANUAL GUIDANCE/00Z GFS REFCST ENSEMBLE MEAN. THIS GUIDANCE SUPPORTS SOME LGT WAD PCPN ON MON/TUE...THEN A DRY DAY ON WED AS HI PRES UNDER AN UPR CONFLUENCE ZN TO THE N OF THE BLDG SE RDG EXPANDS INTO THE AREA. NCEP MANUAL GUIDANCE FAVORS APRCH OF ANOTHER LO PRES ON THU...SO WL GO WITH A CHC OF SN LATER IN THE DAY. HAVE OPTED TO INCLUDE A WINTRY MIX OF PCPN IN THE FCST OF MON AFTN/TUE MRNG AS GFS REFCST ENSEMBLE MEAN H100-5 THKNS AOA 540DM AND OPERATIONAL RUNS SHOWING H85 TEMPS AOA 0C. WL GO WITH TEMPS CLOSER TO WARMER OPERATIONAL GFS MOS GUIDANCE EARLY IN THE WEEK...THEN CLOSER TO COLDER ENSEMBLE MOS GUIDANCE ON WED/THU WITH PROSPECT OF SHALLOW ARCTIC AIR ASSOCIATED WITH HIER PRES SCENARIO. COORDINATED WITH APX/GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING UNTIL 11 PM EST FRIDAY MIZ001-003. LAKE EFFECT SNOW WARNING UNTIL 11 AM EST FRIDAY MIZ006. LAKE EFFECT SNOW WARNING UNTIL 6 AM EST FRIDAY MIZ002. LAKE EFFECT SNOW WARNING UNTIL MIDNIGHT CST TNGT MIZ009. LAKE EFFECT SNOW ADVISORY UNTIL 11 PM EST THIS EVENING MIZ005. LAKE EFFECT SNOW ADVISORY UNTIL 6 AM EST FRIDAY MIZ085. && $$ KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1057 AM EST THU DEC 23 2004 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE SNOW POTENTIAL ACROSS THE FORECAST AREA THIS AFTERNOON. WATER VAPOR IMAGERY AND RUC/ETA SHOWING A LONGWAVE TROUGH ACROSS HUDSON BAY AND CENTRAL CONUS. SHORTWAVES MOVING THROUGH THE BASE OF THIS TROUGH ARE OVER THE LOWER GREAT LAKES...WESTERN ILLINOIS... NORTHWEST WISCONSIN...AND NORTHWEST ONTARIO. SURFACE ANALYSIS INDICATING A LOW OVER THE LOWER GREAT LAKES WITH A WEAK TROUGH STRETCHING WEST ACROSS THE FORECAST AREA. A BROAD RIDGE EXTENDS FROM A HIGH OVER THE WESTERN DAKOTAS THROUGH CENTRAL CANADA AND THROUGH SOUTH CENTRAL PLAINS. 850MB THERMAL TROUGH ACROSS CENTRAL ONTARIO INTO THE DAKOTAS IS PRODUCING TEMPERATURES AROUND -22C ACROSS LAKE SUPERIOR. A 925MB WEAK CYCLONIC FLOW ACROSS THE AREA IS CAUSING SOME CONVERGENCE ALONG THE NORTH SHORE OF LAKE SUPERIOR AND OVER THE WESTERN U.P. THE WISCONSIN WEAK SHORTWAVE WILL MOVE INTO THE WESTERN U.P. THIS AFTERNOON CAUSING THE 850-500MB Q-VECTOR CONVERGENCE TO INCREASE ACROSS THE AREA. MEANWHILE...THE WEAK SURFACE TROUGH WILL REMAIN STATIONARY OVER LAKE SUPERIOR AS THE DAKOTAS/WESTERN ONTARIO RIDGE PUSH INTO NORTHWEST MINNESOTA. THE THERMAL TROUGH WILL SLIDE A LITTLE EAST CAUSING THE 850MB TEMPERATURES OVER LAKE SUPERIOR TO LOWER TO -24C. 925MB CONVERGENCE AREA WILL CONTINUE ALONG THE NORTH SHORE OF LAKE SUPERIOR AND EXPAND OVER THE WESTERN U.P. TO INCLUDE MOST OF THE FORECAST AREA BY 21Z THIS AFTERNOON. ETA SOUNDING FORECASTS INDICATE THE LOWEST INVERSION LEVEL AROUND 3500FEET OVER LAKE SUPERIOR THIS MORNING WILL RISE TO AROUND 6400 FEET BY LATE AFTERNOON. CONDITIONS ARE VERY CONDUCIVE FOR INCREASE LAKE EFFECT SNOW SHOWERS THROUGH THE AFTERNOON. THE AIR MASS IS DRY WITH THE DEW POINTS OVER WESTERN ONTARIO AROUND -26C AND 950MB RH WILL BE AROUND 85 PERCENT PER RUC/ETA40 WHICH WOULD INDICATE A NEED FOR A LITTLE MORE FETCH TIME TO SATURATE OUT THE LOWEST LAYERS. THE LES DECISION TREE STILL SUGGEST AN ADDITIONAL 2 TO 4 INCHES OVER THE WESTERN U.P. THIS AFTERNOON AND 3 TO 6 INCHES OVER SOME OF THE HIGHER TERRAIN OF THE NORTH CENTRAL U.P. WHICH IS CLOSE TO THAT WHICH IS ALREADY FORECASTED. SOME OF THE TEMPERATURES WILL NEED TWEAKING AS WELL. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING MIZ002 THROUGH TONIGHT. LAKE EFFECT SNOW WARNING MIZ009 UNTIL MIDNIGHT TONIGHT. LAKE EFFECT SNOW ADVISORY MIZ005 THROUGH THIS EVENING. LAKE EFFECT SNOW WARNING MIZ001-003 THROUGH FRIDAY EVENING. LAKE EFFECT SNOW WARNING MIZ006 THROUGH FRIDAY MORNING. LAKE EFFECT SNOW ADVISORY MI085 TONIGHT. HEAVY FREEZING SPRAY WARNING E HALF OF LAKE SUPERIOR. && $$ DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 545 AM EST THU DEC 23 2004 .DISCUSSION... MAIN FCST CONCERN CONTINUES TO BE LES AMOUNTS. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A DEEP TROF EXTENDING FROM HUDSON BAY TO THE SRN ROCKIES/PLAINS. A STRONG SHORTWAVE WAS LIFTING NE THRU THE OHIO VALLEY WITH NW EDGE OF ASSOCIATED SNOW SHIELD WELL TO THE SE OF HERE. INCREASINGLY COLDER ARCTIC CONTINUES TO SLOWLY FILTER INTO THE UPPER GREAT LAKES ON NW WINDS. 00Z RAOBS SHOW 850MB TEMPS RANGING FROM -15C/-19C AT KGRB/KAPX RESPECTIVELY TO -24/-25C AT KINL/CWPL. UPSTREAM KINL/CWPL SOUNDINGS SHOWED STABLE BUT MOIST PROFILES...ESPECIALLY CWPL WHICH HAD DWPT DEPRESSIONS LESS THAN 3C ALL THE WAY UP TO 630MB (11.6KFT MSL). AS ANTICIPATED...LOW-LEVEL WINDS HAVE VEERED OVERNIGHT TO A NRLY DIRECTION WHICH HAS RESULTED IN LES SHIFTING BACK INTO MARQUETTE COUNTY AND INCREASING LES INTO GOGEBIC/ONTONAGON COUNTIES. KDLH RADAR IS EVEN PICKING UP LES BANDS STREAMING INTO FAR WRN GOGEBIC COUNTY...SO AT LEAST MDT LES IS OCCURRING THERE. FCST ISSUE TODAY WILL BE LES IN GENERAL NRLY FLOW WHILE ATTENTION TONIGHT/FRI TURNS TO WNW FLOW FAVORED LES BELTS. GOING FCST LOOKS TO HAVE A GOOD HANDLE ON THESE TRENDS. NRLY FLOW TODAY WILL FAVOR NCNTRL FCST AREA WHERE CURRENT ADVY IS IN PLACE AND FAR WRN AREAS (GOGEBIC/ONTONAGON COUNTIES). LOW-LEVEL CONVERGENCE WILL BE STRONGER OVER THE FAR W THAN NCNTRL AS A RESULT OF MORE PRONOUNCED BACKING OF WINDS OVER APOSTLE ISLANDS/FAR NW WI AS IS TYPICAL WITH VERY HIGH LAND-LAKE TEMP DIFFERENCE (NOTE W WIND AT KASX/KIWD...NW WIND AT DISW4 AND NNE WIND AT ONTONAGON). WITH INVERSIONS RUNNING AROUND 6KFT...STRONG LOW-LEVEL CONVERGENCE AND LONG OVERWATER FETCH... SHOULD BE ABLE TO ACHIEVE WARNING CRITERIA AMOUNTS (8 INCHES/12HRS TODAY). WITH WEAKER LOW-LEVEL CONVERGENCE INTO NCNTRL FCST AREA... ADVY AMOUNTS UP TO 6 INCHES SHOULD SUFFICE. TONIGHT/FRI...ETA HAS COME AROUND TOWARD A GFS TYPE SOLUTION WITH REGARD TO LOW-LEVEL WINDS BACKING MORE TONIGHT AS GRADIENT SLACKENS A BIT...ALLOWING STRONGER LAND BREEZE INFLUENCE ON WIND FIELDS. SHORTWAVE DROPPING S TOWARD WRN LAKES ALSO SUPPORTS AT LEAST SOME BACKING OF THE SYNOPTIC LOW-LEVEL FLOW. END RESULT WILL BE BULK OF LES SHIFTING E OF PROBABLY ALL OF MARQUETTE COUNTY THIS EVENING EXCEPT PERHAPS AREAS NEAR BIG BAY AND SHOT POINT. LES SHOULD ALSO SHIFT N OF GOGEBIC COUNTY PROBABLY NEAR OR SHORTLY AFTER MIDNIGHT. THE BACKING OF WINDS ALL ALONG THE SRN SHORE OF LAKE SUPERIOR TO MORE OF A WRLY DIRECTION WHILE FLOW CONTINUES TO BE NW OVER WRN LAKE SUPERIOR AND EVEN MORE NRLY TO NE ACROSS ERN SUPERIOR DUE TO LAND BREEZE OFF ONTARIO WILL LEAD TO PRONOUNCED CONVERGENCE ZONES WHICH SHOULD FOCUS ON ONTONAGON/HOUGHTON COUNTIES AND ALGER COUNTY. HOWEVER...ARCTIC AIR WILL CONTINUE TO STRENGTHEN OVER THE REGION... FURTHER SUPPRESSING FAVORABLE DENDRITIC SNOW GROWTH. ON THE OTHER HAND...DEVELOPING STRONG CONVERGENCE ZONES SHOULD ALLOW FOR MORE LOCAL LOW-LEVEL TEMP MODIFICATION WITHIN SNOW BANDS THAN MODEL SOUNDINGS INDICATE...ALLOWING FOR MORE FAVORABLE SNOW GROWTH. IN ADDITION...WEAK SYNOPTIC FORCING AND DEEPER MOISTURE WILL ENHANCE LES. AT THIS POINT...PREFER TO MAINTAIN GOING WATCHES WHICH BEGIN TONIGHT FOR KEWEENAW/NRN HOUGHTON AND ALGER COUNTIES TO ALLOW ANOTHER MODEL RUN TO PIN DOWN TIMING AND PLACEMENT OF DEVELOPING CONVERGENCE ZONES. GIVEN MAGNITUDE OF PROJECTED CONVERGENCE...SRN HOUGHTON COUNTY MAY NEED AN ADVY TONIGHT...MAINLY FOR AREAS NEAR M38. WELL TO THE E IN LUCE COUNTY...INTERESTING TO SEE ETA AND RUC13 INDICATING SUFFICIENT COLD AIR DRAINAGE OFF ERN ONTARIO TO SHIFT WINDS TO AN ERLY DIRECTION THERE (EVEN GFS HINTS AT THIS). MODELS EVENTUALLY DEVELOP A MESOLOW NEAR GRAND MARAIS (WILL BE INTERESTING TO SEE IF THAT DOES OCCUR). AS A RESULT...LOOKS LIKE LUCE COUNTY MAY SEE LITTLE IN THE WAY OF LES TONIGHT. GFS SHOWS LITTLE CHANGE IN THE CONVERGENCE AREAS FRI WHILE ETA SHIFTS CONVERGENCE N TO THE KEWEENAW AND TO EASTERN ALGER AND PERHAPS FAR NRN LUCE COUNTY. DON'T HAVE A GOOD FEEL FOR WHAT SOLUTION IS BETTER...ESPECIALLY IN LIGHT OF POTENTIAL FOR MESOLOWS TO COMPLICATE WIND FIELDS. AT THIS POINT...WILL STAY THE COURSE WITH GOING FCST WHICH HAS KEWEENAW PENINSULA AND ALGER IN MAIN LES... SIMILAR TO GFS TYPE SOLUTION. LOW-LEVEL WINDS BACK SUFFICIENTLY FRI NIGHT TO BRING AN END TO LES ACROSS ALL OF THE FCST AREA. THERE IS SOME UNCERTAINTY WITH -SN CHC ARRIVING OVER THE WEEKEND IN ASSOCIATION WITH A WEAK SHORTWAVE AND WAA REGIME. HAVE FOLLOWED HPC GUIDANCE WHICH FAVORS A UKMET/CANADIAN SOLUTION...AND WILL THUS BRING -SN CHC INTO THE AREA CHRISTMAS AFTN AS OPPOSED TO THE EVENING. AS FOR TEMPS...DEFINITELY PREFER THE COLDER GFS MOS NUMBERS OVER THE NEXT COUPLE OF DAYS GIVEN SOURCE REGION OF AIRMASS IN SCNTRL CANADA WHERE AFTN HIGHS HAVE ONLY BEEN -10 TO -25F. CORE OF COLDEST AIR WILL BE OVER THE AREA FRI AND WOULD EXPECT MANY AREAS TO STRUGGLE TO REACH ZERO FRI AFTN OVER THE INTERIOR W HALF OF FCST AREA. IF FCST AREA HAD SNOW COVERED FIELDS RATHER THAN FOREST...HIGHS WOULD EVEN BE COLDER. LOWS FRI MORNING WILL PROBABLY APPROACH -20F WHERE THERE IS LESS CLOUD COVER...SAME FOR SAT MORNING IF WAA CLOUDS HOLD OFF LONG ENOUGH. WILL BE CLOSE TO WIND CHILL ADVY CRITERIA DURING THE NIGHTS...BUT IT LOOKS LIKE WINDS SPEEDS SHOULD BE BLO 10MPH THRESHOLD IN THE COLDER AREAS. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING MIZ002 THROUGH TONIGHT. LAKE EFFECT SNOW WARNING MIZ009 UNTIL MIDNIGHT TONIGHT. LAKE EFFECT SNOW ADVISORY TODAY MIZ005-006. LAKE EFFECT SNOW WATCH TONIGHT-FRI MIZ001-003-006-085. HEAVY FREEZING SPRAY WARNING E HALF OF LAKE SUPERIOR. && $$ ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 1015 AM EST THU DEC 23 2004 .SHORT TERM (REST OF TODAY) WILL UPDATE TO RAISE POPS AND ADJUST TEMPS. BASED ON LATEST MODEL AND RADAR DATA...CATEGORICAL POPS WARRANTED FOR REST OF TODAY. WILL SCALE FROM 100 INLAND TO 80 OUTER BANKS. ALSO MINOR TEMP ADJUSTMENT...MAINLY FOR 65-70 SRN OUTER BANKS (ALREADY 69 AT HSE). WILL CONTINUE ISOLD TSTM MENTION BUT LACK OF STRONG INSTABILITY WILL PRECLUDE SVR THREAT. && .AVIATION...MVFR CONDITIONS BECOMING A BIT MORE WIDESPREAD IN ASSOCIATION WITH SHOWERS MOVING INTO THE REGION. HAVE UPDATED TO CONTINUE THESE MVFR CIGS AND VSBYS AS A TEMPORARY CASE THOUGH AS AREAS OUTSIDE SHOWERS ARE STILL VFR. LATER THIS MORNING AND INTO THE AFTN MVFR WILL BECOME THE PREVAILING CONDITION. && .MARINE...LIMITED REAL TIME DATA NEAR SHORE AGAIN TODAY BUT DID NOTICE THAT DUCK COE REPORTS SEAS HAVE REACHED 6 FT 2 MILES OUT. AND WHILE WINDS HAVE YET TO INCREASE WITH QUICK SCAT AND BUOYS SHOWING STRONGER WINDS WELL OFF SHORE FEEL IT IS ONLY A MATTER OF TIME UNTIL NEAR SHORE WINDS BEGIN TO INCREASE AS WELL. SURF CAMS ACROSS NRN WATERS DO NOT LOOK THAT IMPRESSIVE YET BUT WITH DUCK READING OF 6 FT FEEL CURRENT FORECAST TREND OF INCREASING SEAS THROUGH THE DAY IS ON THE RIGHT TRACK. WILL PLAN NO SIG UPDATES THIS MRNG. EARLIER CONCERNS ABOUT MIXING DOWN GALE FORCE WINDS IN CONVECTION STILL AN ISSUE BUT LATEST RUC INDICATES H8 WINDS NOT QUITE AS STRONG AS EARLIER AND WITH RAIN STABILIZES BOUNDARY LAYER THIS MORNING MAY BE MORE DIFFICULT TO MIX THESE DOWN...EXCEPT ALONG FAR EASTERN EDGE OF MARINE ZONES CLOSER TO THE GULF STREAM WHERE WATERS ARE A BIT WARMER AND OVERLYING AIRMASS WILL BE MORE UNSTABLE. STILL FEEL ANY GUSTS WOULD BE SHORT LIVED ENOUGH TO HANDLE WITH SPECIAL MARINE WARNINGS IF NEEDED AS OPPOSED TO A GALE WARNING. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY AMZ130-135-150-152-154-156-158. && $$ SHORT TERM...JBM AVIATION/MARINE...MF nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE COLUMBIA SC 944 PM EST THU DEC 23 2004 .UPDATE... WILL DROP MENTION OF LAKE WIND ADVISORY FOR THE OVERNIGHT PERIOD. WINDS NEVER REALLY PICKED UP DURING THE EVENING AS AREA WAS UNDER A WEAKNESS IN THE ISOBAR FIELD. BEST PACKING REMAINED TO OUR WEST WHERE WINDS WERE A BIT STRONGER ACROSS PORTION OF GA. RUC/MESO ETA INDICATE GRADIENT WILL TIGHTEN OVERNIGHT AS HIGH PRESSURE BUILD IN FROM THE WEST. TIME SECTIONS INDICATE NICE 30 TO 35 KT LOW LEVEL JET OVERNIGHT. THINK WINDS WILL PICK UP AROUND MIDNIGHT AND REMAIN BETWEEN 10 TO 15 THROUGH MORNING...STAYING BELOW LAKE WIND ADVISORY CRITERIA. SATELLITE SHOWS QUITE A BIT OF MID/HIGH CLOUDS UPSTREAM... SO WILL INCREASE CLOUD AMOUNTS FOR THE OVERNIGHT AS WELL. && .PREV DISCUSSION... && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ LCV sc AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 710 PM MST THU DEC 23 2004 .DISCUSSION...CURRENT SURFACE MAP PLACES HIGH PRESSURE OVER THE CENTRAL PLAINS...WITH LEE TROF/WARM FRONT ACROSS CENTRAL MONTANA. TEMPERATURES HAVE DROPPED RAPIDLY THIS EVENING WITH CLEAR SKIES AND LIGHT WINDS. TEMPERATURES AT OR BELOW FORECAST IN MANY AREAS. WARM FRONT MOVES THROUGH EASTERN MONTANA/EASTERN WYOMING TONIGHT...AND ACROSS WESTERN DAKOTAS EARLY FRIDAY. THIS WILL ALLOW TEMPERATURES TO REBOUND SOME...MAINLY IN THE BLACK HILLS AND NORTHEASTERN WYOMING. AREA OF SNOW ACROSS NORTHERN MONTANA ASSOCIATED WITH THE WARM ADVECTION. 00Z RUC SHIFTING BEST LIFT SOUTH AND EAST OVERNIGHT. WITH DRY AIR IN PLACE...AND LATER TIMING OF BEST LIFT...PUSHED HIGHEST POPS BACK UNTIL LATE TONIGHT. STILL LOOKS FAVORABLE FOR PERIOD OF UPSLOPE ENHANCEMENT ACROSS THE NORTHERN BLACK HILLS. WINDS START OUT MORE WESTERLY...SO INITIAL UPSLOPE SNOW WILL IN THE O'NEIL PASS/FOUR CORNERS AREA. && .UNR...WATCHES/WARNINGS/ADVISORIES... .SD...NONE. .WY...NONE. $$ sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 945 PM CST THU DEC 23 2004 .UPDATE... SNOW CONTINUES FROM CARLSBAD TO SNYDER. SO FAR HEAVIEST SNOWFALL AROUND 3 INCHES REPORTED AT CARLSBAD AND STILL FALLING SO HAVE UPGRADE TO A HEAVY SNOW WARNING FOR EDDY AND LEA AND GUADALUPE MOUNTAINS. EDDY COUNTY S.O. REPORTS NUMEROUS PROBLEMS WITH WRECKS AND CARS IN DITCHES AND RECOMMEND DRIVERS THERE STAY OFF OF THE ROAD. .SHORT TERM... MID LEVEL TROF AXIS ORIENTED SW TO NE FROM BAJA CA THRU COLORADO. WATER VAPOR INDICATES SHRTWV TROF IN BASE OF TROF AXIS INVOF BAJA CA WITH ANOTHER SHRTWV IN WRN AZ. MID LEVEL ASCENT LOOKS TO BE JUST STARTING TO COMMENCE WITH IR INDICATING COOLING TOPS IN W/CENTRAL NM. ETA40/RUC IN EXCELLENT AGREEMENT IN GENERATING STRONG LIFT (PER INCREASING UPGLIDE ALONG I285-290K/7H WAA ALONG/PVA) ACRS SE NM BTWN 21Z-03Z. TIME/HEIGHT SECTIONS INDICATE SE NM IS FAVORED AREA FOR SNOW CRYSTAL GROWTH. MODEL QPF GUIDANCE HAS BEEN CONSISTENT IN GENERATING PRECIP ACRS SE NM/NW PB/UPPER TRANS PECOS GIVING CONFIDENCE TO CRITERIA FOR SNOW ADVISORY (2-4 INCHES) BEING MET. THUS ISSUED SNOW ADVISORY EARLIER FOR SE NM AND GDP MTNS. WILL CONTINUE TO HOLD OFF ON MOVING ADVISORY CONDITIONS FARTHER E AND S...ALTHOUGH NW PB...VAN HORN REGION...AND DAVIS MTNS COULD SEE AROUND 2 INCHES BEFORE SUNRISE. LATER SHIFTS WILL NEED TO MONITOR FOR UPDATES. 1 INCH OR LESS EXPECTED IN MIDLAND/ODESSA. SNOW COVER AND CLEARING SKIES ALLOWED LOWS TO FALL TO AROUND 10 ACRS NW-NE CWFA THIS MORNING. LATEST SFC PLOT INDICATES NEXT SURGE OF ARCTIC AIR IS MVG INTO OKLA PANHANDLE AND WILL BE INTO PB BEFORE SUNRISE. THUS ANOTHER COLD NIGHT WITH HARD FREEZE. NE WINDS WILL INCREASE 15-20 MPH MOST AREAS WITH ARCTIC AIR...GUSTS TO 45 MPH THRU GDP PASS. .LONG TERM... HIGH AMPLITUDE FLOW PATTERN CONSISTING OF A WEST COAST RIDGE AND A TROUGH OVER THE GREAT PLAINS WILL UNDERGO A SIGNIFICANT CHANGE BY SUNDAY AS AN UPPER LEVEL TROUGH DEVELOPS OVER THE ERN PAC/PAC NW WITH RIDGING IN STORE FOR THE PLAINS. THE MEDIUM RANGE MODELS ARE CONSISTENT IN CONTINUING THIS LARGE-SCALE MID AND UPPER LEVEL FLOW PATTERN THROUGH EARLY NEXT WEEK. DIFFERENCES ARISE WITH REGARDS TO A SHORTWAVE TROUGH PROGGED TO AFFECT OUR AREA ON WEDNESDAY. THIS FEATURE COULD BRING A SHOT OF RAIN TO THE AREA...OTHERWISE NEAR NORMAL TEMPERATURES AND DRY CONDITIONS ARE EXPECTED THIS FORECAST. AS FOR THE DETAILS...A STRONG MID-LEVEL SHORTWAVE IN THE BASE OF A LONGWAVE TROUGH CURRENTLY TRANSLATING SOUTH AND EAST THROUGH THE ROCKIES WILL REMAIN IN CLOSE ENOUGH PROXIMITY TO THE SOUTHERN AND WESTERN 1/3 OF THE AREA TO CONTINUE LOW ORDER CHANCE POPS THROUGH EARLY TOMORROW MORNING. MID-LEVEL OMEGA FIELDS INDICATE WEAK LIFT WILL GENERALLY WANE BY MIDDAY FRIDAY. THE HIGHER TERRAIN WILL SEE THE BEST CHANCES FOR ACCUMULATING SNOWFALL THROUGH TOMORROW MORNING WITH THE ABOVE MENTIONED LIFT AND EASTERLY UPSLOPE FLOW. NEGATING FACTOR FOR SIGNIFICANT ACCUMULATIONS WILL BE THE VERY DRY BOUNDARY LAYER THAT WILL ENCOMPASS THE AREA BY LATE TOMORROW MORNING. MID AND UPPER LEVEL HEIGHTS BEGIN TO RISE BY LATE SATURDAY AND THIS TREND WILL CONTINUE INTO EARLY NEXT WEEK. TEMPERATURES WILL GRADUALLY WARM ACROSS THE AREA OVER THE NEXT COUPLE OF DAYS. WE HAVE OPTED TO GENERALLY STAY BELOW GUIDANCE AS MODELS TEND TO SCOUR COLD AIR OUT TOO QUICKLY. TEMPERATURES WILL BE COOLEST OVER SOUTHEAST NEW MEXICO WHERE SOME SNOW COVER WILL BE LIKELY. SURFACE LEE-SIDE TROUGH COMBINED WITH SURFACE HIGH PRESSURE OVER THE GULF COASTAL STATES WILL RETURN SOUTHERLY WINDS...AND EVENTUALLY SOME LOW-LEVEL MOISTURE TO THE AREA BY WEDNESDAY MORNING. THIS MOISTURE MAY COMBINE WITH A PASSING UPPER LEVEL SHORT WAVE TROUGH FOR A SLIGHT CHANCE OF RAIN ON WEDNESDAY. WE WILL LEAVE THE CHANCE OF RAIN IN THE FORECAST...BUT IF THE TREND OF THE ECMWF/UKMET MODELS CONTINUES...WE MAY NEED TO PULL OR DELAY RAIN CHANCES. && .PRELIMINARY POINT TEMPS/POPS... BIG SPRING TX 13 29 18 48 / 50 10 0 0 CARLSBAD NM 14 29 16 49 / 70 30 0 0 DRYDEN TX 20 36 19 51 / 30 20 0 0 FORT STOCKTON TX 19 33 23 51 / 50 30 0 0 GUADALUPE PASS TX 11 26 18 41 / 60 40 0 0 HOBBS NM 15 31 17 48 / 70 10 0 0 MARFA TX 14 26 11 45 / 50 40 0 0 MIDLAND INTL AIRPORT TX 15 30 18 47 / 60 10 0 0 ODESSA TX 15 31 18 48 / 60 10 0 0 WINK TX 17 35 18 52 / 60 20 0 0 && .MAF WATCHES/WARNINGS/ADVISORIES... TX...HEAVY SNOW WARNING TONIGHT FOR GUADALUPE MOUNTAINS TXZ258. SNOW ADVISORY TONIGHT NORTHWESTERN PERMIAN BASIN. TXZ045-046-050-051. NM...SNOW ADVISORY TONIGHT FOR ALL OF SOUTHEASTERN NEW MEXICO... NMZ027>029-033-034. && $$ tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 605 PM CST THU DEC 23 2004 .UPDATE... EXPANDED SNOW ADVISORY TO INCLUDE 4 COUNTIES IN WESTERN PERMIAN BASIN AS AREA OF MODERATE SNOWFALL EXPANDING EASTWARD. SNOW-LINE APPEARS TO JUST CLIP NORTHERN PORTIONS OF ECTOR COUNTY AND HAVE CHOSEN TO LEAVE IT OUT AT THIS TIME. IF SNOW BUILDS SOUTHWARD LATER UPDATES MAY BE NECESSARY. .SHORT TERM... MID LEVEL TROF AXIS ORIENTED SW TO NE FROM BAJA CA THRU COLORADO. WATER VAPOR INDICATES SHRTWV TROF IN BASE OF TROF AXIS INVOF BAJA CA WITH ANOTHER SHRTWV IN WRN AZ. MID LEVEL ASCENT LOOKS TO BE JUST STARTING TO COMMENCE WITH IR INDICATING COOLING TOPS IN W/CENTRAL NM. ETA40/RUC IN EXCELLENT AGREEMENT IN GENERATING STRONG LIFT (PER INCREASING UPGLIDE ALONG I285-290K/7H WAA ALONG/PVA) ACRS SE NM BTWN 21Z-03Z. TIME/HEIGHT SECTIONS INDICATE SE NM IS FAVORED AREA FOR SNOW CRYSTAL GROWTH. MODEL QPF GUIDANCE HAS BEEN CONSISTENT IN GENERATING PRECIP ACRS SE NM/NW PB/UPPER TRANS PECOS GIVING CONFIDENCE TO CRITERIA FOR SNOW ADVISORY (2-4 INCHES) BEING MET. THUS ISSUED SNOW ADVISORY EARLIER FOR SE NM AND GDP MTNS. WILL CONTINUE TO HOLD OFF ON MOVING ADVISORY CONDITIONS FARTHER E AND S...ALTHOUGH NW PB...VAN HORN REGION...AND DAVIS MTNS COULD SEE AROUND 2 INCHES BEFORE SUNRISE. LATER SHIFTS WILL NEED TO MONITOR FOR UPDATES. 1 INCH OR LESS EXPECTED IN MIDLAND/ODESSA. SNOW COVER AND CLEARING SKIES ALLOWED LOWS TO FALL TO AROUND 10 ACRS NW-NE CWFA THIS MORNING. LATEST SFC PLOT INDICATES NEXT SURGE OF ARCTIC AIR IS MVG INTO OKLA PANHANDLE AND WILL BE INTO PB BEFORE SUNRISE. THUS ANOTHER COLD NIGHT WITH HARD FREEZE. NE WINDS WILL INCREASE 15-20 MPH MOST AREAS WITH ARCTIC AIR...GUSTS TO 45 MPH THRU GDP PASS. .LONG TERM... HIGH AMPLITUDE FLOW PATTERN CONSISTING OF A WEST COAST RIDGE AND A TROUGH OVER THE GREAT PLAINS WILL UNDERGO A SIGNIFICANT CHANGE BY SUNDAY AS AN UPPER LEVEL TROUGH DEVELOPS OVER THE ERN PAC/PAC NW WITH RIDGING IN STORE FOR THE PLAINS. THE MEDIUM RANGE MODELS ARE CONSISTENT IN CONTINUING THIS LARGE-SCALE MID AND UPPER LEVEL FLOW PATTERN THROUGH EARLY NEXT WEEK. DIFFERENCES ARISE WITH REGARDS TO A SHORTWAVE TROUGH PROGGED TO AFFECT OUR AREA ON WEDNESDAY. THIS FEATURE COULD BRING A SHOT OF RAIN TO THE AREA...OTHERWISE NEAR NORMAL TEMPERATURES AND DRY CONDITIONS ARE EXPECTED THIS FORECAST. AS FOR THE DETAILS...A STRONG MID-LEVEL SHORTWAVE IN THE BASE OF A LONGWAVE TROUGH CURRENTLY TRANSLATING SOUTH AND EAST THROUGH THE ROCKIES WILL REMAIN IN CLOSE ENOUGH PROXIMITY TO THE SOUTHERN AND WESTERN 1/3 OF THE AREA TO CONTINUE LOW ORDER CHANCE POPS THROUGH EARLY TOMORROW MORNING. MID-LEVEL OMEGA FIELDS INDICATE WEAK LIFT WILL GENERALLY WANE BY MIDDAY FRIDAY. THE HIGHER TERRAIN WILL SEE THE BEST CHANCES FOR ACCUMULATING SNOWFALL THROUGH TOMORROW MORNING WITH THE ABOVE MENTIONED LIFT AND EASTERLY UPSLOPE FLOW. NEGATING FACTOR FOR SIGNIFICANT ACCUMULATIONS WILL BE THE VERY DRY BOUNDARY LAYER THAT WILL ENCOMPASS THE AREA BY LATE TOMORROW MORNING. MID AND UPPER LEVEL HEIGHTS BEGIN TO RISE BY LATE SATURDAY AND THIS TREND WILL CONTINUE INTO EARLY NEXT WEEK. TEMPERATURES WILL GRADUALLY WARM ACROSS THE AREA OVER THE NEXT COUPLE OF DAYS. WE HAVE OPTED TO GENERALLY STAY BELOW GUIDANCE AS MODELS TEND TO SCOUR COLD AIR OUT TOO QUICKLY. TEMPERATURES WILL BE COOLEST OVER SOUTHEAST NEW MEXICO WHERE SOME SNOW COVER WILL BE LIKELY. SURFACE LEE-SIDE TROUGH COMBINED WITH SURFACE HIGH PRESSURE OVER THE GULF COASTAL STATES WILL RETURN SOUTHERLY WINDS...AND EVENTUALLY SOME LOW-LEVEL MOISTURE TO THE AREA BY WEDNESDAY MORNING. THIS MOISTURE MAY COMBINE WITH A PASSING UPPER LEVEL SHORT WAVE TROUGH FOR A SLIGHT CHANCE OF RAIN ON WEDNESDAY. WE WILL LEAVE THE CHANCE OF RAIN IN THE FORECAST...BUT IF THE TREND OF THE ECMWF/UKMET MODELS CONTINUES...WE MAY NEED TO PULL OR DELAY RAIN CHANCES. && .PRELIMINARY POINT TEMPS/POPS... BIG SPRING TX 13 29 18 48 / 50 10 0 0 CARLSBAD NM 14 29 16 49 / 70 30 0 0 DRYDEN TX 20 36 19 51 / 30 20 0 0 FORT STOCKTON TX 19 33 23 51 / 50 30 0 0 GUADALUPE PASS TX 11 26 18 41 / 60 40 0 0 HOBBS NM 15 31 17 48 / 70 10 0 0 MARFA TX 14 26 11 45 / 50 40 0 0 MIDLAND INTL AIRPORT TX 15 30 18 47 / 60 10 0 0 ODESSA TX 15 31 18 48 / 60 10 0 0 WINK TX 17 35 18 52 / 60 20 0 0 && .MAF WATCHES/WARNINGS/ADVISORIES... TX...SNOW ADVISORY TONIGHT FOR THE GUADALUPE MOUNTAINS OF CULBERSON COUNTY AND PORTIONS OF WESTERN PERMIAN BASIN... TXZ045-046-050-051-258. NM...SNOW ADVISORY TONIGHT FOR ALL OF SOUTHEASTERN NEW MEXICO... NMZ027>029-033-034. && $$ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 245 PM CST THU DEC 23 2004 .SHORT TERM... MID LEVEL TROF AXIS ORIENTED SW TO NE FROM BAJA CA THRU COLORADO. WATER VAPOR INDICATES SHRTWV TROF IN BASE OF TROF AXIS INVOF BAJA CA WITH ANOTHER SHRTWV IN WRN AZ. MID LEVEL ASCENT LOOKS TO BE JUST STARTING TO COMMENCE WITH IR INDICATING COOLING TOPS IN W/CENTRAL NM. ETA40/RUC IN EXCELLENT AGREEMENT IN GENERATING STRONG LIFT (PER INCREASING UPGLIDE ALONG I285-290K/7H WAA ALONG/PVA) ACRS SE NM BTWN 21Z-03Z. TIME/HEIGHT SECTIONS INDICATE SE NM IS FAVORED AREA FOR SNOW CRYSTAL GROWTH. MODEL QPF GUIDANCE HAS BEEN CONSISTENT IN GENERATING PRECIP ACRS SE NM/NW PB/UPPER TRANS PECOS GIVING CONFIDENCE TO CRITERIA FOR SNOW ADVISORY (2-4 INCHES) BEING MET. THUS ISSUED SNOW ADVISORY EARLIER FOR SE NM AND GDP MTNS. WILL CONTINUE TO HOLD OFF ON MOVING ADVISORY CONDITIONS FARTHER E AND S...ALTHOUGH NW PB...VAN HORN REGION...AND DAVIS MTNS COULD SEE AROUND 2 INCHES BEFORE SUNRISE. LATER SHIFTS WILL NEED TO MONITOR FOR UPDATES. 1 INCH OR LESS EXPECTED IN MIDLAND/ODESSA. SNOW COVER AND CLEARING SKIES ALLOWED LOWS TO FALL TO AROUND 10 ACRS NW-NE CWFA THIS MORNING. LATEST SFC PLOT INDICATES NEXT SURGE OF ARCTIC AIR IS MVG INTO OKLA PANHANDLE AND WILL BE INTO PB BEFORE SUNRISE. THUS ANOTHER COLD NIGHT WITH HARD FREEZE. NE WINDS WILL INCREASE 15-20 MPH MOST AREAS WITH ARCTIC AIR...GUSTS TO 45 MPH THRU GDP PASS. .LONG TERM... HIGH AMPLITUDE FLOW PATTERN CONSISTING OF A WEST COAST RIDGE AND A TROUGH OVER THE GREAT PLAINS WILL UNDERGO A SIGNIFICANT CHANGE BY SUNDAY AS AN UPPER LEVEL TROUGH DEVELOPS OVER THE ERN PAC/PAC NW WITH RIDGING IN STORE FOR THE PLAINS. THE MEDIUM RANGE MODELS ARE CONSISTENT IN CONTINUING THIS LARGE-SCALE MID AND UPPER LEVEL FLOW PATTERN THROUGH EARLY NEXT WEEK. DIFFERENCES ARISE WITH REGARDS TO A SHORTWAVE TROUGH PROGGED TO AFFECT OUR AREA ON WEDNESDAY. THIS FEATURE COULD BRING A SHOT OF RAIN TO THE AREA...OTHERWISE NEAR NORMAL TEMPERATURES AND DRY CONDITIONS ARE EXPECTED THIS FORECAST. AS FOR THE DETAILS...A STRONG MID-LEVEL SHORTWAVE IN THE BASE OF A LONGWAVE TROUGH CURRENTLY TRANSLATING SOUTH AND EAST THROUGH THE ROCKIES WILL REMAIN IN CLOSE ENOUGH PROXIMITY TO THE SOUTHERN AND WESTERN 1/3 OF THE AREA TO CONTINUE LOW ORDER CHANCE POPS THROUGH EARLY TOMORROW MORNING. MID-LEVEL OMEGA FIELDS INDICATE WEAK LIFT WILL GENERALLY WANE BY MIDDAY FRIDAY. THE HIGHER TERRAIN WILL SEE THE BEST CHANCES FOR ACCUMULATING SNOWFALL THROUGH TOMORROW MORNING WITH THE ABOVE MENTIONED LIFT AND EASTERLY UPSLOPE FLOW. NEGATING FACTOR FOR SIGNIFICANT ACCUMULATIONS WILL BE THE VERY DRY BOUNDARY LAYER THAT WILL ENCOMPASS THE AREA BY LATE TOMORROW MORNING. MID AND UPPER LEVEL HEIGHTS BEGIN TO RISE BY LATE SATURDAY AND THIS TREND WILL CONTINUE INTO EARLY NEXT WEEK. TEMPERATURES WILL GRADUALLY WARM ACROSS THE AREA OVER THE NEXT COUPLE OF DAYS. WE HAVE OPTED TO GENERALLY STAY BELOW GUIDANCE AS MODELS TEND TO SCOUR COLD AIR OUT TOO QUICKLY. TEMPERATURES WILL BE COOLEST OVER SOUTHEAST NEW MEXICO WHERE SOME SNOW COVER WILL BE LIKELY. SURFACE LEE-SIDE TROUGH COMBINED WITH SURFACE HIGH PRESSURE OVER THE GULF COASTAL STATES WILL RETURN SOUTHERLY WINDS...AND EVENTUALLY SOME LOW-LEVEL MOISTURE TO THE AREA BY WEDNESDAY MORNING. THIS MOISTURE MAY COMBINE WITH A PASSING UPPER LEVEL SHORT WAVE TROUGH FOR A SLIGHT CHANCE OF RAIN ON WEDNESDAY. WE WILL LEAVE THE CHANCE OF RAIN IN THE FORECAST...BUT IF THE TREND OF THE ECMWF/UKMET MODELS CONTINUES...WE MAY NEED TO PULL OR DELAY RAIN CHANCES. && .PRELIMINARY POINT TEMPS/POPS... BIG SPRING TX 13 29 18 48 / 50 10 0 0 CARLSBAD NM 14 29 16 49 / 70 30 0 0 DRYDEN TX 20 36 19 51 / 30 20 0 0 FORT STOCKTON TX 19 33 23 51 / 50 30 0 0 GUADALUPE PASS TX 11 26 18 41 / 60 40 0 0 HOBBS NM 15 31 17 48 / 70 10 0 0 MARFA TX 14 26 11 45 / 50 40 0 0 MIDLAND INTL AIRPORT TX 15 30 18 47 / 60 10 0 0 ODESSA TX 15 31 18 48 / 60 10 0 0@ RUKWBC , KK FFGOHX NATIONAL WEATHER SERVICE LOWER MISSISSIPPI RIVER FORECAST CENTER, SLIDELL LA 243 PM CST THU DEC 23 2004 FLASH FLOOD GUIDANCE FOR CWA.....NASHVILLE TN INCHES OF RAINFALL FOR SPECIFIED DURATIONS REQUIRED TO PRODUCE FLASH FLOODING IN ANY SMALL STREAM WITHIN FORECAST ZONES. LOWER AMOUNTS MAY CAUSE FLASH FLOODING IN URBAN OR MOUNTAINOUS AREAS. .B SIL 041223 Z DH18/DC0412232043 /DUE/PPHCF/PPTCF/PPQCF :IDENTIFIERS ARE STATE ID, Z FOR ZONE, NWS-MAR ZONE NUMBER. : :...STATE DURATION :IDENT 1HR 3HR 6HR ZONE NAME :======= ==== ==== ==== ==================== : :.....TENNESSEE : TNZ075 1.0/ 1.4/ 1.7 :BEDFORD TNZ022 1.2/ 1.6/ 1.9 :BENTON TNZ077 1.0/ 1.3/ 1.6 :COFFEE TNZ066 0.9/ 1.2/ 1.6 :CUMBERLAND TNZ055 1.0/ 1.4/ 1.6 :DECATUR TNZ095 1.0/ 1.3/ 1.7 :GILES TNZ079 1.2/ 1.5/ 1.8 :GRUNDY TNZ057 0.8/ 1.2/ 1.6 :HICKMAN TNZ023 1.3/ 1.6/ 2.0 :HOUSTON TNZ024 1.1/ 1.5/ 1.8 :HUMPHREYS TNZ094 1.1/ 1.4/ 1.7 :LAWRENCE TNZ058 0.9/ 1.3/ 1.6 :LEWIS TNZ061 1.1/ 1.4/ 1.7 :MARSHALL TNZ060 1.0/ 1.3/ 1.6 :MAURY TNZ056 1.0/ 1.3/ 1.6 :PERRY TNZ093 1.0/ 1.3/ 1.6 :WAYNE .END $$ DUTY FORECASTER: CALL LMRFC OPERATIONS tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1023 AM EST THU DEC 23 2004 CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER NWRN PA WITH A STRONG N-S COLD FRONT THROUGH WRN PA...WV...AND FAR WRN VA. FRONT IS MAKING VERY SLOW EWRD PROGRESS...GIVEN THE DEGREE OF MERIDIONAL FLOW AS THE LOW-MID LEVEL STEERING WINDS ARE NEARLY PARALLEL TO THE FRONT. THE MAIN CONCERN FOR THIS AFTN...OTHER THAN THE SHOWERS AHEAD OF THE FRONT...WILL BE WITH THE WINDS. VAD WIND PROFILES ACROSS THE REGION SHOW VERY STRONG WINDS NOT FAR OFF THE SURFACE...INCLUDING 60KTS AT 2 KFT HERE AT KAKQ. CERTAINLY...THE DEGREE OF LOW LEVEL STABILITY (REFER TO KWAL 12Z SOUNDING) IS INHIBITING THE BULK OF THIS MOMENTUM FROM REACHING THE GROUND. HOWEVER...THE CONCERN INITIALLY WILL BE THAT SOME OF THESE SHOWERS (DEEPER CONVECTION) WILL BE A LITTLE MORE EFFICIENT IN BRINGING DOWN THE HIGHER WIND SPEEDS. THEN...AFTER 3 PM...EXPECT A SECONDARY SURGE OF HIGHER SUSTAINED WINDS/GUSTS ACCOMPANYING THE FRONTAL PASSAGE...AS THE LOW LEVEL CAP ERODES WITH THE ONSET OF CAA. THE COLD ADVECTION WILL TAKE A WHILE IN DEEPENING THROUGH THE LOW LEVELS...HOWEVER...AS RUC MODEL SOUNDINGS SHOW AN INVERSION REMAINING BTWN 900-800 MB WITH A BACKING VERTICAL WIND PROFILE (NW NEAR THE SURFACE AND SW AROUND 850 MB AND ABOVE). THEREFORE...GIVEN THE LACK OF DEEP INSTBY AND (THUS) LACK OF ALIGNED WINDS IN THE LOWER LAYERS...DO NOT EXPECT THE STRONGER POST-FRONTAL WINDS TO LAST FOR MORE THAN 1-3 HOURS. CONSIDERING ALL OF THIS AND PER COORDINATION WITH PHI...WILL BE HOISTING A WIND ADVISORY FOR THE LOWER ERN SHORE THIS AFTN...AS GIVEN THE ONSHORE COMPONENT (LESS FRICTIONAL DIMINISHMENT) THIS REGION IS MOST SUSCEPTIBLE TO THE HIGHER WIND GUST POTENTIAL WITH S/SSW WINDS. ELSEWHERE...FOR NOW WILL JUST CONTINUE TO HIGHLIGHT THE WINDY CONDITIONS (20-30 MPH) W/O AN ADVISORY. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...WIND ADVISORY...THROUGH 7 PM...MDZ021>025. NC...SCA CSTL WTRS AND CURRITUCK SND. VA...SCA CSTL WTRS AND SRN CHES BAY. MARINE...SMALL CRAFT ADVISORY FOR ZONES ANZ630>632-650-652-654-656- 658-633 THROUGH FRIDAY. && HURLEY PREVIOUS DISCUSSION BELOW... ------------------------------------------------------------------- .SHORT TERM (TODAY THROUGH FRIDAY NIGHT)...MILD AGAIN TDY AS STRNG SOUTHERLY WNDS IN ADVANCE OF COLD FRNT...HELPS BOOST TEMPS INTO THE UPR 50S TO MID 60S DESPITE CLDS/PCPN. LO PRES OVR ERN KY ERLY THIS MRNG...WILL MOVE NNE TDY INTO TNGT PULLING THE COLD FRNT ACRS REGION WITH SHRAS/POSSIBLE TSRAS. LATE THIS MRNG THRU THIS AFTN...SHRAS/TSRAS MAY CONTAIN GUSTY WNDS BUT SHUD BE BELOW SVR LVLS (58 MPH). FRNT PUSHES WELL OFFSHR LATER TNGT...WITH N WNDS USHERING VRY DRY AIR INTO FA THRU SAT AS HI PRES BLDS TWD/INTO REGION. && .LONG TERM (SATURDAY THROUGH WEDNESDAY)...HI PRES BLDS OVR FA ON SAT...PROVIDING LOTS OF SUNSHINE BUT COLD MAX TEMPS RANGING THRU THE 30S. HI PRES WILL REMAIN OVR THE AREA...THEN SLIDE OFF THE MID ATLC CST FOR SUN THRU WED. STILL VRY CHILLY ON SUN...BUT TEMPS THEN REBOUND BACK TO ARND 60/LWR 60S BY WED. && .AVIATION...VFR CONDS BECOMING MVFR TO OCNL IFR DUE TO PCPN TDY INTO THIS EVENG. && .MARINE...SCA CONDS EXPECTED THIS AFTN THRU FRI...AS STRNG S WNDS IN ADVANCE OF FRNT SHIFT TO N AND REMAIN STRNG DUE TO CAA. && $$ SHORT TERM/LONG TERM...32 AVIATION/MARINE...25 va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 358 AM CST FRI DEC 24 2004 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT OF MAIN CONCERN THIS EARLY MORNING ARE HIGH TEMPERATURES TODAY AND MINIMUMS TONIGHT. THE LATEST RUC80 MODEL IS THE PREFERRED MODEL AND IT STILL SHOWS A WEAK UPPER SHORT WAVE MOVING ACROSS MY CW AREA TODAY. THE LATEST SATELLITE IMAGERY LOOPS REVEAL SCATTERED TO BROKEN CIRRUS AND A FEW ALTO-CUMULUS ACROSS MOST OF THE REGION. THE COMBINATION OF LOW TEMPERATURES THIS MORNING AND SOME WIND WILL YIELD LOW WIND CHILLS SO WILL ALLOW THE ON-GOING WIND CHILL ADVISORY TO CONTINUE IN EFFECT UNTIL 8 AM THIS FRIDAY MORNING. A WEAK COLD FRONT ASSOCIATED WITH THE UPPER LEVEL SYSTEM WILL BE MOVING ACROSS THE AREA TODAY AND EARLY TONIGHT. THIS WILL REINFORCE THE COLD AIR NOW IN PLACE. THE RESIDUAL SNOW COVER AND PATCHY ICE WILL CONTINUE TO PLAY A ROLE IN THE TEMPERATURE TRENDS TODAY...TONIGHT AND INTO CHRISTMAS. (38) && .LONG TERM...MONDAY THROUGH THURSDAY RATHER STRONG UPPER RIDGE MOVES INTO THE AREA FOR THE FIRST PART OF THE WEEK WHILE THE ARCTIC HIGH AFFECTING THIS AREA IN THE SHORT TERM MOVES TO THE EAST AND WARMER AIR RETURNS TO THE AREA. NEW GFS KEEPS A SURFACE RIDGE IN THE AREA THROUGH NEXT THURSDAY. ALSO STRONG UPPER LOW STAYS OFF THE WEST COAST THROUGH MUCH OF THE PERIOD WITH A SHORT WAVE FINALLY MOVING INTO THE PLAINS ABOUT THURSDAY. THIS SOULTION APPEARS TO BE SLOWER THAN EARLIER RUNS AND RESULTED IN SOME SIGNIFICANT CHANGES. SURFACE PATTERN FAVORS MORE OF A SOUTHEAST WIND TO MOST AREAS WITH SOUTH TO SOUTHWEST WINDS IN THE NORTHWEST. ALSO SKIES SHOULD BE MOSTLY CLEAR TO PARTLY CLOUDY INTO THE MIDDLE OF THE WEEK. THE SURFACE RIDGE SHOULD BE SET UP TO KEEP THE GULF CLOSED AND LESSEN THE CHANCE FOR STRATUS. THIS MAY BREAK DOWN ON WEDNESDAY AND SHOWED INCREASING CLOUDS THEN. REALLY LOOKS LIKE ANY CHANCES FOR RAIN WILL HOLD OFF UNTIL THURSDAY BUT LEFT SMALL POPS IN FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. AIR WILL STILL BE RATHER STABLE TUESDAY NIGHT INTO WEDNESDAY SO ONLY WENT WITH RAIN FOR NOW. AS THE UPPER SHORT WAVE COMES OUT THURSDAY AND A STRONG SURFACE LOW DEVELOPS IN RESPONSE...INSTABILITY WILL LIKELY INCREASE...SO PUT IN SHOWERS AND THUNDERSTORMS FOR THURSDAY AFTERNOON. (29) && .PRELIMINARY POINT TEMPS/POPS... LITTLE ROCK AR 30 12 36 24 / 0 0 0 0 HARRISON AR 24 14 35 24 / 0 0 0 0 HOT SPRINGS AR 30 13 38 24 / 0 0 0 0 PINE BLUFF AR 30 14 37 24 / 0 0 0 0 MOUNTAIN HOME AR 22 13 33 22 / 0 0 0 0 MONTICELLO AR 30 15 38 24 / 0 0 0 0 SEARCY AR 26 10 33 21 / 0 0 0 0 MOUNT IDA AR 29 10 39 23 / 0 0 0 0 RUSSELLVILLE AR 28 9 37 21 / 0 0 0 0 && .LZK WATCHES/WARNINGS/ADVISORIES...WIND CHILL ADVISORY UNTIL 800 AM CST TODAY FOR ZONES ARZ003>007... ARZ012>016...ARZ021>024...ARZ031. && $$ 38/29 ar AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE MARQUETTE MI 1045 AM EST FRI DEC 24 2004 .DISCUSSION... OBVIOUS CONCERN WITH THIS UPDATE IS CURRENT LES AND HEADLINES. THE HEADLINE FOR ALGER COUNTY IS SET TO EXPIRE AT 11 AM...AND WILL PROBABLY CANCEL IT AT THAT TIME. PESKY MESO-VORTEX OVER EASTERN LAKE SUPERIOR IS CONTINUING TO PRODUCE SIGNIFICANT CONVERGENCE AND LES OVER FAR EASTERN ALGER COUNTY AND NORTHWEST LUCE COUNTY...BUT EXPECT THE MESO-VORTEX TO SLOWLY LOST SOME OF ITS STRUCTURE THROUGHOUT THE DAY AS THE ADJACENT LAND MASSES WARM SOME AND THE LAND BREEZES RELAX. THE 12Z ETA AND LOCAL WORKSTATION ETA BOTH KEEP SNOW SHOWER ACTIVITY GOING ACROSS THIS AREA THROUGH THE AFTERNOON...BUT SUGGEST A WEAKENING TREND. AMOUNTS OVERNIGHT AS HIGH AS 8 INCHES WERE REPORTED FROM MUNISING. FEEL ADDITIONAL AMOUNTS THIS AFTERNOON WILL BE MINIMAL OVER MOST OF ALGER COUNTY...WITH 1 TO LOCALLY 4 INCHES POSSIBLE NEAR GRAND MARAIS DUE TO THE BANDING ON THE SOUTH SIDE OF THE MESO-VORTEX. WILL MENTION THESE ACCUMULATIONS IN THE FORECAST UPDATE...BUT ALLOW THE HEADLINE TO BE CANCELLED. OVER THE KEWEENAW...HEAVY SNOW HAS BEEN REPORTED AT KCMX FOR MUCH OF THE MORNING WITH A FAVORABLE WEST WIND BRINGING SNOW TO NORTHERN HOUGHTON COUNTY. SNOWFALL OVER THE NORTHERN KEWEENAW HAS BEEN LIMITED DUE TO THE PERSISTING NORTHWEST WIND IN THAT AREA...BUT WOULD EXPECT THE HEAVIER SNOWFALL TO SHIFT SLOWLY INTO THAT AREA THROUGH THE AFTERNOON AS THE BOUNDARY LAYER FLOW BECOMES MORE SOUTHWESTERLY. THINGS ACROSS THE ENTIRE CWFA ARE CURRENTLY BEING ENHANCED BY THE SHORTWAVE WHICH CAN BE SEEN IN THE WATER VAPOR IMAGERY AND RUC ANALYSES SWINGING ACROSS LAKE SUPERIOR. INVERSION HEIGHTS ARE EXPECTED TO DESCEND...WITH ATTENDANT DRYING...LATER THIS AFTERNOON AND THIS EVENING...WITH SOMEWHAT UNFAVORABLE FLOW AND THERMODYNAMICS PROGGED OVER THE KEWEENAW BY EARLY EVENING. THIS WILL HAVE TO BE EVALUATED FURTHER...SINCE IT MAY ALLOW FOR THE KEWEENAW HEADLINE TO BE SHORTENED. TEMPERATURES ACROSS THE CWFA ARE SLOW TO REBOUND THIS MORNING...AND HAVE TWEAKED BACK FORECAST HIGHS A BIT TO LINE UP BETTER WITH CURRENT TRENDS. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING UNTIL 11 PM EST THIS EVENING MIZ001-003. && $$ TRH mi AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE MARQUETTE MI 515 AM EST FRI DEC 24 2004 .DISCUSSION... MAIN FCST CONCERNS ARE LES TRENDS AND WIND CHILLS. WV IMAGERY AND RUC ANALYSIS INDICATED A HIGH AMPLITUDE PATTERN WITH A RDG FROM THE EPAC INTO THE PAC NW AND A LONG WAVE TROF AXIS FROM HUDSON BAY THROUGH THE WRN LAKES TOWARD THE SRN PLAINS. AN UPSTREAM SHRTWV OR SHEAR AXIS EXTENDED FROM NW ONTARIO TO W LK SUPERIOR. AT THE SFC...ARCTIC HIGH PRES STRETCHED FROM NRN MANITOBA TOWARD THE SRN PLAINS WHILE A LAKES INDUCED TROF EXTENDED FROM NRN LK MI NW TO S AND W LK SUPERIOR. RADAR INDICATED CONVERGENT BAND OF SHSN INTO E ALGER COUNTY. TODAY AND TONIGHT...WHILE 850 TO 700 MB TEMPS (-24C TO -34C) PRODUCED VERY STRONG INSTABILITY...SNOW GROWTH IN SUCH AN ARCTIC AIRMASS WOULD BE NORMALLY BE UNFAVORABLE. HOWEVER...THERMAL RDGING MOISTURE/HEAT FLUX IN DOMINANT/CONVERGENT BANDS VCNTY TROF...SHOULD STILL LEAD TO DECENT SNOWFLAKE GROWTH. OVER THE WEST...ETA FCST 950 CONV KEEPS FOCUS VCNTY KCMX THIS MORNING BEFORE SHIFTING NORTH TO NEAR KP59 THIS EVENING. SO EXPECT LOCAL SNOWFALL RATES TO AT LEAST AN INCH/HOUR TODAY. SHIFTING POSITION OF SNOW BAND SHOULD LIMIT OVERALL ACCUMULATIONS INTO THE 3-7 INCH RANGE. ETA LOW LVL WINDS ALSO SUGGEST E LAKE CONVERGENCE BAND WILL GRADUALLY SHIFT EASTWARD. ENOUGH UNCERTAINTY ON EVOLUTION OF MESO-LOW REMAINS TO JUSTIFY CONTINUED SCT/NMRS SHSN NEAR THE SHORE INTO THIS EVENING EVEN IF ETA SUGGESTS LES WILL MOVE OFF SHORE. MIXING IN AREAS WITH WINDS AOA 10 MPH HAS KEPT TEMPS UP WHILE COLDEST READINGS WERE GENERALLY IN LOCATIONS WITH WINDS BLO 10 MPH. SO...EVEN WITH CURRENT WIND CHILLS MAINLY IN THE 15 TO 25 BELOW RANGE...PREVAILING CONDITIONS ABV ADVY CRITERIA (25 BELOW...WINDS AOA 10 MPH) EXPECTED AS TEMPS SLOWLY REBOUND THIS MORNING. EVEN THOUGH ARCTIC AIRMASS REMAINS OVER UPR MICHIGAN...ENOUGH WAA CLOUDS MAY LIMIT RADIATIONAL COOLING. NEVERTHELESS...INLAND READINGS FCST INTO THE -12F TO -17F RANGE WITH TEMPS NEAR ZERO ALONG THE LAKE SHORES. SATURDAY...WHILE THE ETA SHOWS BEST SATURATION WITH 280K-290K ISENTROPIC LIFT SLIDING SOUTH OF UPR MI AND MOISTURE IS SCANT...-SN CHANCE RETAINED AS WEAK TO MODERATE QG FORCING AHEAD OF THE SHRTWV LOBE MOVING BRUSHES UPR MI. SAT NIGHT INTO SUN...ETA/GFS/UKMET BLEND SUGGESTS THAT AS THE SFC TROF PIVOTS THROUGH S OF THE AREA AND NRN ONTARIO HIGH BUILDS SOUTHWARD...CYCLONIC NNE WINDS WILL DEVELOP ACRS LK SUPERIOR WITH FOCUS OF BEST LOW LVL CONV INTO N CNTRL UPR MI. IF MORE FAVORABLE ETA SCENARIO WITH MORE AGGRESSIVE NRLY WINDS DEVELOPS...ADVY LEVEL SNOWFALL AMOUNTS WOULD BE POSSIBLE GIVEN INVERSION HGTS STARTING NEAR 7K-8K FT. EXPECT THE ETA MAY HAVE BETTER HANDLE ON LOW LVL WINDS WITH ITS DEPICTION OF MORE PRONOUNCED GREAT LAKE AGGREGATE TROFFING. MON INTO TUE...GOING FCST OF -SN CHANCES STILL LOOKS ON TRACK WITH DEVELOPING STRONG WAA PATTERN. MDLS TREND HAS BEEN TOWARD KEEPING DEEP COLD AIR MORE ENTRENCHED WITH THICKNESS VALUES SUPPORTING ALL SNOW DURING PERIOD OF MOST FAVORABLE LIFT. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING UNTIL 11 PM EST THIS EVENING MIZ001-003. LAKE EFFECT SNOW WARNING UNTIL 11 AM EST TODAY MIZ006. && $$ JLB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE RALEIGH NC 1030 AM EST FRI DEC 24 2004 .UPDATE... NO UPDATE NEEDED. 150KT JET ALOFT AND SW FLOW ALOFT WILL CONTINUE TO PRODUCE EXTENSIVE CIRRUS STRATUS DECK ACROSS THE CWA TODAY. THE LOWER STRATUS LAYER ACROSS THE EASTERN HALF OF CWA EAST ASSOCIATED WITH 850 TROUGH AND CONVERGENCE AREA. THE RUC AND MESOETA SHOW THIS FEATURE MOVING VERY LITTLE DURING THE COURSE OF THE DAY...NOT SHIFTING EAST UNTIL AFTER 00Z. LOWER CLOUD BASE WILL HAVE GREATER IMPACT ON TEMPERATURES ACROSS THE EAST... THUS EXPECT MINIMAL SPREAD ACROSS THE CWA THIS AFTERNOON. NORTHERLY WINDS WILL DECENT WIND GUSTS (~17KTS) WILL ADD EXTRA CHILL TO THE AIR. FORECAST HIGHS OF 40 TO 43 LOOK ON TRACK. SEE NO REASON TO UPDATE. && .PREV DISCUSSION (TODAY THROUGH SUNDAY NIGHT)... OVERALL... ALOFT BROAD UPPER TROUGH OVER THE REGION THROUGH THE HOLIDAY WEEKEND WHILE HIGH PRESSURE DOMINATES AT THE SURFACE. LOW LEVELS DRYING OUT. BUT HIGH LEVEL CLOUDS SPREADING UP FROM SOUTHWEST IN RESPONSE SOUTHERN JET AND CUTOFF FROM SOUTHERN TEXAS AND ASSOCIATED SURFACE WAVE SLIDING EAST ALONG THE GULF COAST REGION. THIS TO RESULT IN HIGH LEVEL CLOUDS ACROSS THE CWA TODAY THROUGH EARLY SATURDAY. MOST OF THIS STAY SUPPRESSED TO OUR SOUTH. OTHERWISE BASICALLY A TEMPERATURE FORECAST DURING THIS PERIOD. STRONG CAA CONVECTION TODAY THROUGH SATURDAY NIGHT...WITH SATURDAY NIGHT COLDEST DURING THIS PERIOD. HIGHS TODAY WILL AVERAGE 15-20 DEGREES COLDER THAN YESTERDAY AS HIGHS RANGE FROM MID 60S NORTHWEST TO AROUND 70 SOUTHEAST. HIGH LEVEL CLOUDS COULD RETARD MAXES A BIT TODAY...THUS WILL TWEAK DOWN A FEW DEGREES. SOME MORNING CLOUDS SATURDAY...THEN CLEAR AND COLD FOR SATURDAY/SATURDAY NIGHT. TEMPERATURES BEGIN TO MODERATE ON SUNDAY BUT STILL BELOW SEASONAL NORMS. && .LONG TERM (MONDAY THROUGH WEDNESDAY)... THE NEW WEEK TO START WITH HIGH AMPLITUDE RIDGE BUILDING IN THE CENTRAL CONUS. RIDGE FLATTENS TOWARD MID WEEK RESULTING IN NEARLY ZONAL FLOW AS S/W EAST ALONG NORTHERN TIER CONUS. ALL IN ALL...A DRY WEEK ACROSS THE REGION WITH MODERATING TEMPERATURES..RETURNING CLOSER SEASONAL NORMS. && .AVIATION... COLD FRONT WELL OFFSHORE AS OF 06Z/24 DEC. LOW LEVEL MOISTURE HAD SINCE SCOURED OUT... LEAVING BROKEN CIRRUS ABOVE. SURFACE WINDS WERE GUSTY JUST BEHIND THE FRONT... BUT SINCE SUBSIDED TO LESS THAN 10 KNTS... DUE IN PART TO WEAKNESS IN THE SURFACE PRESSURE FIELD IN THE LEE OF THE MOUNTAINS INTO THE PIEDMONT. THE PRESSURE GRADIENT SHOULD BECOME TIGHTER AFTER 09Z... BUT BY THAT TIME WE MAY BE DECOUPLED FROM WINDS ABOVE THE BOUNDARY LAYER. WILL INCREASE WINDS TO 11-12 KNOTS AROUND SUNRISE WITH BROKEN TO OVERCAST CIRRUS ALL DAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NC...NONE. && $$ UPDATE...BL nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE COLUMBIA SC 1046 AM EST FRI DEC 24 2004 .UPDATE... CAE 88D PICKING UP SOME PRETTY GOOD ECHOES ENTERING THE SOUTHERN PART OF THE CAE CWA. 35-45 DBZ RETURNS FROM BURKE COUNTY,GA WAS CONFIRMED BY THE BURKE CO SHERIFF OFFICE AS SLEET. MODELS SHOW SHALLOW MOISTURE LAYER IN THE LOW LEVELS 2-3 THOUSAND FEET BUT A DRY LAYER FROM 850MB-700MB ABOUT 5-10 THOUSAND FEET. RUC/MESOETA TIME SECTIONS FROM SOUTHERN PART OF CWA INCLUDING BARNWELL AND ORANGEBURG COS INDICATE SOME MOISTENING UP OF DRY LAYER THIS AFTERNOON. WILL UPDATE SOUTHERN ZONES TO GO 30 PERCENT CHANCE LIGHT RAIN AND SLEET FROM BURKE CO, GA NORTHEAST THROUGH CLARENDON CO. WILL ALSO INCLUDE A 20 PERCENT CHANCE OF SLEET CENTRAL MIDLANDS FROM AUGUSTA,GA TO COLUMBIA TO SUMTER. WILL LOWER HIGHS TO THE MID TO UPPER 30S. NO CHANGE TO TONIGHT FORECAST SINCE MODELS JUST HAVE A QUICK SHOT OF LOW LEVEL MOISTURE WHICH IS GONE BY SUNSET. && .PREV DISCUSSION... .SHORT TERM...(FRI-SUN)...LONG WAVE TROUGH OVER THE AREA WILL HOLD IN THROUGH THE WEEKEND AS AN UPPER DISTURBANCE WILL SLIDE TO OUR SOUTH...JUST ABOUT A COUPLE OF HUNDRED MILES NORTH ON THE LOW TRACK AND WE WOULD HAVE A VERY DIFFERENT SITUATION...HOWEVER THE CIRRUS DECK ASSOCIATED WITH THE DISTURBANCE WILL KEEP SKIES MOSTLY CLOUDY TODAY AND TONIGHT WITH SOME MINOR ADJUSTMENTS TO TEMPS MADE FOR EACH PERIOD. WINDS WILL BE PICKING UP A BIT SAT NIGHT AS THE LOW PASSE BY, HAVE BUMPED UP MINS BIT SAT PM DUE TO WINDS. THINGS CLEAR OUT SUN WITH MODERATING TEMPS. && .LONG TERM...(MON-FRI)...ZONAL FLOW SETS UP WITH UPPER RIDGE BUILDING IN FROM THE WEST SFC HIGH WILL NOSE DOWN THE EAST COAST AND KEEP US DRY FOR THE WEEK WITH MODERATING TEMPS APPROACHING NEAR NORMAL BY MID WEEK AND ABOVE NORMAL BY THE END OF THE WEEK. && .AVIATION... VFR CONDITIONS SHOULD CONTINUE THROUGH THE PERIOD. EXPECT NORTHEAST WINDS NEAR 10 KNOTS BEHIND A REINFORCING COLD FRONT TODAY WITH WINDS DIMINISHING TO NEAR 5 KNOTS AROUND SUNSET. THERE MAY BE SOME COLD ADVECTION STRATOCUMULUS BUT IT/S PROBABLY TOO DRY FOR A MVFR CEILING. UPPER-LEVEL CLOUDINESS SHOULD BE ON THE INCREASE ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF THE H25 JET. && .PRELIMINARY POINT TEMPS/POPS... COLUMBIA 44 30 48 27 / 0 0 0 10 AUGUSTA 43 28 49 28 / 0 0 0 10 SUMTER 44 29 48 27 / 0 0 0 10 ORANGEBURG 44 30 48 28 / 0 0 0 10 && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 07/19 sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 1045 AM EST FRI DEC 24 2004 .UPDATE SHORT TERM...WILL GO AHEAD AND MENTION SLIGHT CHANCE OF MIX PCPN ENTIRE CWA THIS AFTN. A COUPLE OF REPORTS HAVE ALREADY COME IN MENTIONING PCPN IN SC COUNTIES. STILL NO ACCUMULATIONS EXPECTED. PREVIOUS DISCURRION .SHORT TERM /TODAY THROUGH TONIGHT/...LOOKING AT SATELLITE...RADARS OVER THE SE AND SFC OBS...SPOTTY LIGHT PCPN IS HITTING THE GROUND THIS MORNING ALONG THE GULF COAST STATES AND EVEN INTO SW GA. MOISTURE PRESENTLY LIMITED WITH DEWPTS IN THE LOW TO MID 30S AND MAY DROP A FEW MORE DEGREES OVER SC COUNTIES. HOWEVER WITH MOISTURE ADVECTION INTO SW GA THIS MORNING...EXPECT ENUF MOISTURE TO MOVE INTO GA PTN OF CWA TO SEE PCPN THIS AFTN AND CONTINUE INTO SC COUNTIES THIS EVENING. COULD SEE A MIXTURE OF PCPN SO WILL START IT OUT AS RAIN PSBLY MIXED WITH SLEET WITH NO ACCUMULATIONS EXPECTED. && .LAKE WINDS...PINEVILLE OBS HAVE COME IN AT 10-15 KT THE PAST COUPLE OF HRS. BEST PRES GRAD LOOKS TO REMAIN OFFSHORE WHILE HIGH PRES BUILDS INLAND SO WILL CONTINUE TO LOOK FOR DECRG SPEEDS BUT NOT QUITE AS MUCH AS CURRENT FCST HAS. WILL DECRS WINDS TO 15 KT TDA THEN BLEND IT BETTER FOR TNGT. && .MARINE...WINDS RATHER STUBBORN TO SETTLE DOWN TDA AS PER BUOYS AND PILOT BOAT REPORTS. BUOYS...SHORELINE OBS...AND CHS PILOT BOAT ALL REPORTING 15-20 KT WIND SPEEDS. CULPRIT IS A FAIRLY TIGHT SFC PRES GRAD OVER THE WATERS BETWEEN STALLED FRONT WELL OFFSHORE AND BUILDING HIGH INLAND. BOTH RUC AND M-ETA SHOW PRES GRAD TO REMAIN OVER THE WATERS THRU THE DAY WITH WINDS NOT DROPPING OFF AS PREV EXPECTED. WILL ADJUST SPEEDS TDA TO MAINTAIN UPPER RANGES OF WIND SPEEDS THRU THIS AFTN AND ALSO SLIGHTLY INCRS WINDS TNGT AS SPEEDS DO NOT LOOK TO DROP OFF MUCH TNGT...PARTICULARLY DURG AN ANTICIPATED OVRNGT SURGE. WAVES LOOK ON TRACK SO NO CHANGES NEEDED THERE. . && .AVIATION...MVFR CIGS WILL CONTINUE TO PLAGUE KCHS THRU AT LEAST MIDDAY AS LLVL MOISTURE SHIFTS OFF TO THE NE. WILL MAINTAIN TEMPO CIGS AS LOW AS 1500FT UNDER PREVAILING HIGH BKN SKIES. VIS SAT PIX SHOWING BREAKS IN THE CLOUDS ARND KSAV...SO SCT/BKN HIGH CIGS LOOK TO SUFFICE. MAY NEED TO AMD FOR INCRD WIND SPEEDS THIS MRNG...ESP KCHS...AS BOTH SITES SHOWING WIND SPEEDS A BIT ABV GOING VALUES. LWR LVLS STILL LOOK TOO DRY TO INCLUDE PRECIP SO WILL MAINTAIN DRY TAFS. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY AMZ374. && $$ JH/JPC sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 951 AM EST FRI DEC 24 2004 .SHORT TERM /TODAY THROUGH TONIGHT/...LOOKING AT SATELLITE...RADARS OVER THE SE AND SFC OBS...SPOTTY LIGHT PCPN IS HITTING THE GROUND THIS MORNING ALONG THE GULF COAST STATES AND EVEN INTO SW GA. MOISTURE PRESENTLY LIMITED WITH DEWPTS IN THE LOW TO MID 30S AND MAY DROP A FEW MORE DEGREES OVER SC COUNTIES. HOWEVER WITH MOISTURE ADVECTION INTO SW GA THIS MORNING...EXPECT ENUF MOISTURE TO MOVE INTO GA PTN OF CWA TO SEE PCPN THIS AFTN AND CONTINUE INTO SC COUNTIES THIS EVENING. COULD SEE A MIXTURE OF PCPN SO WILL START IT OUT AS RAIN PSBLY MIXED WITH SLEET WITH NO ACCUMULATIONS EXPECTED. && .LAKE WINDS...PINEVILLE OBS HAVE COME IN AT 10-15 KT THE PAST COUPLE OF HRS. BEST PRES GRAD LOOKS TO REMAIN OFFSHORE WHILE HIGH PRES BUILDS INLAND SO WILL CONTINUE TO LOOK FOR DECRG SPEEDS BUT NOT QUITE AS MUCH AS CURRENT FCST HAS. WILL DECRS WINDS TO 15 KT TDA THEN BLEND IT BETTER FOR TNGT. && .MARINE...WINDS RATHER STUBBORN TO SETTLE DOWN TDA AS PER BUOYS AND PILOT BOAT REPORTS. BUOYS...SHORELINE OBS...AND CHS PILOT BOAT ALL REPORTING 15-20 KT WIND SPEEDS. CULPRIT IS A FAIRLY TIGHT SFC PRES GRAD OVER THE WATERS BETWEEN STALLED FRONT WELL OFFSHORE AND BUILDING HIGH INLAND. BOTH RUC AND M-ETA SHOW PRES GRAD TO REMAIN OVER THE WATERS THRU THE DAY WITH WINDS NOT DROPPING OFF AS PREV EXPECTED. WILL ADJUST SPEEDS TDA TO MAINTAIN UPPER RANGES OF WIND SPEEDS THRU THIS AFTN AND ALSO SLIGHTLY INCRS WINDS TNGT AS SPEEDS DO NOT LOOK TO DROP OFF MUCH TNGT...PARTICULARLY DURG AN ANTICIPATED OVRNGT SURGE. WAVES LOOK ON TRACK SO NO CHANGES NEEDED THERE. . && .AVIATION...MVFR CIGS WILL CONTINUE TO PLAGUE KCHS THRU AT LEAST MIDDAY AS LLVL MOISTURE SHIFTS OFF TO THE NE. WILL MAINTAIN TEMPO CIGS AS LOW AS 1500FT UNDER PREVAILING HIGH BKN SKIES. VIS SAT PIX SHOWING BREAKS IN THE CLOUDS ARND KSAV...SO SCT/BKN HIGH CIGS LOOK TO SUFFICE. MAY NEED TO AMD FOR INCRD WIND SPEEDS THIS MRNG...ESP KCHS...AS BOTH SITES SHOWING WIND SPEEDS A BIT ABV GOING VALUES. LWR LVLS STILL LOOK TOO DRY TO INCLUDE PRECIP SO WILL MAINTAIN DRY TAFS. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY AMZ374. && $$ JH/JPC sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1041 AM EST FRI DEC 24 2004 DO NOT ANTICIPATE MUCH (IF ANY) CHANGE TO THE AFTERNOON FORECASTS. COLDER AIR CONTINUES TO GRADUALLY FILTER IN...MAINLY AT LOW LEVELS AT THIS POINT HOWEVER GIVEN THE STRONG LOW LEVEL INVERSION AND BACKING WIND PROFILE ABOVE 850 MB (FROM 12Z KWAL SOUNDING). MEANWHILE...EXTENSIVE WARM CONVEYOR BELT MOISTENING CONTINUES ALOFT PER THE STLT LOOPS...WITH THE MOISTURE CONNECTION (OVERRUNNING THE BROAD ARCTIC AIRMASS) EXTENDING THROUGH MEXICO AND SOUTH OF BAJA. CLOUDS ARE GENERALLY AOA 12 KFT N OF THE VA/NC BORDER...THOUGH SOME LOWER CEILINGS (AOB 6 KFT) WERE NOTED ACROSS SERN VA/NERN NC. THINK THE INCREASING OVER-WATER INSTBY DOWNWIND FROM CHES BAY AND ATLANTIC COASTAL WATERS IS AT LEAST IN SOME WAY CONTRIBUTING TO THE DEVELOPMENT OF THESE LOWER CLOUDS. WILL LIKELY WORK A MORE PESSIMISTIC SKY FORECAST FOR THE SRN ZONES...GIVEN THE DEEPER MOISTURE. FOR THE REST OF THE REGION (N AND W OF SERN VA)...WILL CALL IT PARTLY SUNNY. DO NOT LOOK FOR ANY PRECIP REACHING THE GROUND THIS AFTERNOON...GIVEN THE DRY NORTHERLY ISALLOBARIC FLOW AT LOW LEVELS. *PERHAPS* A STRAY SPRINKLE OR FLURRY OVER NERN NC...THOUGH EVEN IN THIS REGION RUC MODEL SOUNDING SHOW A DEEP LAYER OF DRY AIR (BTWN 850-650 MB)...GREATER THAN 5 KFT IN DEPTH AND AS SUCH WOULD PRECLUDE ICE SEEDING INTO THE LOWER MOIST LAYER. MARINE FORECAST...MINIMAL CHANGES MADE AS SMALL CRAFT ADVISORIES CONTINUE AREAWIDE. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FOR ALL MARINE ZONES. && HURLEY PREVIOUS DISCUSSION BELOW... --------------------------------------------------------------------- .SYNOPSIS/OVERVIEW... AFTER THE WELL ABV NORM TEMPS OF THE PAST 2 DAYS...BIG CHANGES ON THE WAY AS A MUCH COLDER AIRMASS OVERTAKES THE MID ATLC REGION TODAY. SPLIT FLOW REGIME OVR EASTERN STATES KEEPS PCPN CHCS AT A MINIMUM THRU WEEKEND AND INTO EARLY NEXT WEEK. TEMPS REBOUND TO NEAR SEASONAL NORMS EARLY NEXT WEEK THEN BACK ABV NORM BY MIDWEEK AS UPR RDGG GRADUALLY RETURNS TO MID ATLC REGION. && .SHORT TERM (TODAY THROUGH SATURDAY NIGHT)... SHALLOW COLD DOME WILL BUILD OVR REGION TODAY. ONLY A SMALL RISE IN TEMPS EXPECTED (5-10 DEGS) AS READINGS START OUT MOSTLY IN THE 30S (EXCEPT L40S FAR SE). QUITE BRISK ESP CSTL AREAS THIS MORN THEN WIND GRADUALLY DIMINISHES AS STRONG LOW LVL CAA SURGE SUBSIDES THIS AFTN. ONLY LIMITED SUN EXPECTED TODAY AS WELL WITH LAYERED CLOUDS...LOW CLOUDS STUCK UNDER INVERSION MNLY OVR EASTERN AREAS AND MID/HIGH CLOUDS WELL IN ADV OF SOUTHERN STREAM SYS. SFC WAVE DEVELOPS ON OLD FRONT OVR GULF STREAM TNGT BUT SHUD RMN FAR ENUF OFFSHORE TO KEEP ANY ASSOCD PCPN SE OF FORECAST AREA. CLOUDS LIKELY LINGER THRU MUCH OF OVRNGT ESP OVR SE AREAS BEFORE BROAD UPR TROF PUSHES THRU SAT MORN. QUITE COLD TNGT ESP INLAND AS 8H TEMPS CONT TO DROP BUT LINGERING CLOUDS AND SFC MIXING PREVENT FULL TEMP DROPOFF POTENTIAL. STRONG SOUTHERN STREAM SYS MOVES ACRS GULF COAST SAT THEN OFF FLA/GA COAST SAT NIGHT. MID/UPR CONVERGENCE OVR MID ATLC REGION SHUD SUPRESS SYS FAR ENUF SOUTH TO HAVE LTL EFFECT ON FORECAST AREA. CONT COLD THO WITH LOW LVL THICKNESS INDICATING HIGHS ONLY IN THE 30S FOR MOST ON CHRISTMAS DAY. WILL ALSO SEE TIGHTENING PGRAD/INCRSG WINDS AGN ALONG COAST WITH SYS OFF SE COAST AND STRONG HIGH TO NORTH. COLD AGAIN SAT NIGHT WITH MANY LOWS IN THE TEENS INLAND/20S CST. && .LONG TERM (SUNDAY THROUGH THURSDAY)... SLOW WARMING TREND BEGINS SUNDAY AS UPR RDG GRADUALLY BUILDS OVR EASTERN STATES. NORTHERN STREAM SYS RIDES THRU NRN MID ATLC/NE STATES TUE NIGHT BUT LENDS LTL UPR SUPPORT OR DEEP MOISTURE FOR ANY PCPN OVR CNTRL MID ATLC REGION. SHUD FINALLY SEE BETTER RETURN FLOW SET UP BY MIDWEEK AND A RETURN TO ABV NORM TEMPS. && .AVIATION...SOME LOW CLOUDS REMAIN TODAY BUT EXPECT CIGS ABV VFR CRITERIA NEXT 24 HOURS. && .MARINE...SMALL CRAFT ADV ALL AREAS TODAY. PGRAD WILL RMN STRONG BTWN SE COASTL SYS AND STRONG HIGH TO NORTH THRU MUCH OF WEEKEND. LONG FETCH SHUD KEEP SEAS UP AS WELL. && $$ SHORT TERM/LONG TERM...CULLEN AVIATION/MARINE...BROWN va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 316 PM EST FRI DEC 24 2004 .DISCUSSION... THE MAIN CONCERN FOR THIS FORECAST PACKAGE IS THE SNOW POTENTIAL FOR TONIGHT AND CHRISTMAS. WATER VAPOR IMAGERY AND RUC/ETA SHOWING A CLOSED LOW OVER NORTHERN ONTARIO EMBEDDED IN A LONGWAVE TROUGH OVER EASTERN CANADA AND CONUS. A BROAD RIDGE BLANKETS THE NORTHERN ROCKIES. A CLOSED LOW SWINGING THROUGH THE BASE OF THE LONGWAVE TROUGH IS OVER NORTHERN MEXICO. WEAK SHORTWAVES MOVING THROUGH THE BASE OF THE LONGWAVE TROUGH ARE OVER EASTERN U.P. AND OVER SOUTHERN MANITOBA. SURFACE ANALYSIS INDICATE A RIDGE OVER THE MIDDLE MISSISSIPPI RIVER VALLEY STRETCHING NORTH THROUGH THE UPPER GREAT LAKES INTO CENTRAL ONTARIO. AN ELONGATED SURFACE TROUGH STRETCHES FROM THE CANADIAN ROCKIES INTO THE DAKOTAS. REMNANTS OF A WEAK FRONT REMAINS OVER UPPER MICHIGAN CAUSING LOW LEVEL CONVERGENCE ACROSS THE LAKE. 850MB TEMPERATURE ARE AROUND -21C ACROSS LAKE SUPERIOR CAUSING A SIGNIFICANT LAPSE RATE AND GENERATE SCATTERED LAKE EFFECT SNOW SHOWERS. THE ONTARIO MID LEVEL LOW WILL EDGE SOUTHEAST A FEW MILES OVERNIGHT. A WEAK SHORTWAVE WILL SLIDE ACROSS LAKE SUPERIOR. THE SURFACE LOW OVER THE CANADIAN ROCKIES WILL SLIDE INTO THE DAKOTAS. A WEAK FRONTAL SYSTEM WILL REMAIN STATIONARY ACROSS SOUTHERN LAKE SUPERIOR. CYCLONIC FLOW AROUND THE LOW OVER THE DAKOTAS IS CAUSING THE WINDS TO SHIFT SOUTHWEST. THE WEAK FRONTAL SYSTEM OVER LAKE SUPERIOR WILL WASH OUT AND THE LOW LEVEL CONVERGENCE IS EXPECTED TO WEAKEN AS WELL. GFS/ETA BOTH SHOW THE CONVERGENCE REMAINING OVER EASTERN LAKE SUPERIOR THIS EVENING. THE WINDS WILL BECOME ANTI-CYCLONIC OVER THE CENTRAL U.P. TONIGHT. 950MB INDICATE DRIER AIR SPREADING INTO THE CENTRAL U.P. MORE STABLE CONDITIONS...WIND BACKING WEST AND DRIER AIR ENTERING THE AREA...IT LOOKS SAFE TO KEEP THE LES GOING THIS EVENING ESPECIALLY OVER THE KEWEENAW PENINSULA AND NORTHEAST CWA...BUT DIMINISHING IT BY MIDNIGHT. THE CLOSED LOW OVER NORTHERN ONTARIO WILL SHIFT CLOSER TO JAMES BAY ON SATURDAY. ANOTHER SHORTWAVE WILL DEVELOP ON ITS FLANK AND SWEEP INTO NORTHERN LAKE SUPERIOR. THE DAKOTA SURFACE LOW WILL SHIFT DEEPER IN TO THE PLAINS WITH A TROUGH EXTENDING NORTHEAST INTO THE U.P. A SURFACE RIDGE WILL BLANKET NORTHERN ONTARIO AND CENTRAL QUEBEC. THE 850MB TEMPERATURE OVER LAKE SUPERIOR WILL LOWER TO 19C AND 925MB RH WILL REMAIN AROUND 80 PERCENT. WINDS WILL VEER SOUTH ENDING ANY LES OVER THE NORTHERN U.P. HOWEVER...WITH A SOUTHERLY COMPONENT...SURFACE-850MB DELTA-T'S OVER 20C+ MODELS SHOWING LOW LEVEL CONVERGENCE OVER THE DOOR PENINSULA. CONDITIONS LOOK FAVORABLE FOR LES ALONG THE NORTH LAKE MICHIGAN SHORE. CYCLONIC FLOW ACROSS LAKE SUPERIOR ALSO SUPPORTS SOME CONVERGENCE OF EASTERN LAKE SUPERIOR. THUS LAKE EFFECT SNOW WILL KICK BACK IN. THIS TIME WITH SNOWFALL OVER THE LES PRONE AREAS WITH A NORTHEAST FLOW. THE NORTHERN LAKE SUPERIOR SHORTWAVE WILL SHIFT ACROSS THE FORECAST AREA ON SUNDAY MORNING. A SURFACE RIDGE WILL PUSH INTO ONTARIO AND MINNESOTA CAUSING THE WINDS TO BECOME ANTI-CYCLONIC LATE SUNDAY MORNING...DEVELOPING STRONG DIVERGENCE OVER THE AREA. A LITTLE DRIER AND COLDER AIR MASS IS PROGGED TO SPREAD ACROSS THE LAKE. DELTA-T'S STILL AROUND 24C WILL KEEP BANDS OF THE LES GOING FOR MUCH OF THE AREA SUNDAY AFTERNOON...HOWEVER...WITH DIVERGENCE AND DRIER AIR... SNOWFALL WILL BECOME LIMITED. A WEAK SHORTWAVE WILL SHIFT ACROSS THE U.P. SUNDAY NIGHT. A SURFACE RIDGE WILL SHIFT ACROSS THE AREA. DELTA-T'S WILL REMAIN AROUND 20C. THE WINDS WILL VEER SOUTH AND STRONG DIVERGENCE OVER THE AREA WILL END LAKE EFFECT SNOWS. HOWEVER...WITH THE INSTABILITY OF THE SHORTWAVE PASSING OVER THE AREA. BOTH ETA/GFS SHOWING MEAN SURFACE-500MB BETWEEN 75 AND 95 PERCENT ACROSS THE AREA. THIS SHOULD BE ADEQUATE TO PRODUCE SOME SYSTEM TYPE SNOW ACROSS THE AREA. THE QUESTION IS IF THE SURFACE RIDGE WILL BE STABLE ENOUGH TO KEEP THE PRECIPITATION FROM OCCURRING. GFS SUGGEST KEEP PRECIPITATION IN WHILE ETA CONSIDER IT TO DRY. NCEP FAVOR THE ETA SOLUTION. PLAN TO KEEP A CHANCE GOING. ETA/GFS SHOWING A WEAK SHORTWAVE MOVING ACROSS THE FORECAST AREA ON MONDAY. GFS SHOWING A DEEPER SHORTWAVE PASSING OVER NORTHEAST LAKE SUPERIOR. SURFACE RIDGE WILL SHIFT OFF TO THE EAST. DELTA-T'S STILL AROUND 16C. HOWEVER...THE WINDS WILL BE OUT OF THE SOUTHWEST BEHIND THE RIDGE. ETA BRINGING LOW LEVEL MOISTURE AND A SHORTWAVE INTO THE FORECAST AREA LATE ON MONDAY...WHEREAS GFS KEEP THIS TO THE NORTHEAST OF THE FORECAST AREA. THE DGEX MODEL SUGGEST KEEPING IT IN. SINCE THE SNOW IS IN THE FORECAST ALREADY WILL NOT TAKE IT OUT SINCE I LACK ENOUGH CONFIDENCE IN LATEST ETA. THE MID LEVEL SHORTWAVE WILL MOVE INTO MANITOBA AND THE NORTH PLAINS AS A WEAK SHORTWAVE SLIDES OVER THE U.P. A COLD FRONT WILL SLIDE INTO THE MINNESOTA. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL GENERATE A CHANCE FOR SOME SNOW MONDAY NIGHT. THE SHORTWAVE AND COLD FRONT WILL BECOME MORE PRONOUNCED AS THEY SWINGS THROUGH THE FORECAST AREA ON TUESDAY AND TUESDAY NIGHT. A SURFACE RIDGE WILL SHIFT OVER THE FORECAST AREA ON WEDNESDAY AND MOVE QUICKLY TO THE MID ATLANTIC STATES. A WEAK MID LEVEL RIDGE WILL MOVE ACROSS THE FORECAST AREA AND MOVE NORTHEAST. ANTI-CYCLONIC FLOW BEHIND THE FRONT WILL DRAW WARMER AIR INTO THE AREA. THE MID LEVEL RIDGE WILL BUILD OVER THE GREAT LAKES THROUGH THURSDAY WHILE SURFACE LOW MOVES INTO MINNESOTA DRAGGING A COLD FRONT INTO THE MIDDLE MISSISSIPPI RIVER VALLEY. THE SURFACE LOW WILL TRACK ACROSS THE FORECAST AREA ON FRIDAY. INSTABILITY ACCOMPANYING THIS SYSTEM SHOULD GENERATE SOME PRECIPITATION. GFS INDICATE THAT THE 850MB TEMPERATURES WILL BE AROUND ZERO OVER THE AREA. THINK GFS IS WARMING THE AIR TOO MUCH SO WILL KEEP JUST A CHANCE OF EACH. GFS EXTENDED MOS LOOKING FOR SURFACE TEMPERATURES AROUND 0C. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING UNTIL 11 PM EST THIS EVENING MIZ001-003. && $$ DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 253 PM EST FRI DEC 24 2004 .SHORT TERM... MODELS HAVE BECOME MORE AGGRESSIVE SPREADING PRECIPITATION INTO EASTERN AND SOUTHERN SOUTH CAROLINA...ESPECIALLY SUNDAY. CAN NOT IGNORE POSSIBLE WINTER WEATHER...ALTHOUGH AT THIS TIME...APPEARS TO BE MINOR EVENT. WATER VAPOR SHOWING UPPER TROUGH CENTERED IN THE GREAT LAKES/SOUTHERN CANADA NOW AMPLIFYING...WITH SHORT WAVES MOVING SOUTHEAST ACROSS MIDWEST/OHIO VALLEY. UPPER LOW CUT OFF IN NORTHERN MEXICO MOVING SOUTHEAST. SOUTHERN STREAM MOISTURE SPREADING NORTHEAST FROM WESTERN GULF OF MEXICO ACROSS GULF COASTAL STATES TO CAROLINAS. WEAK SHORT WAVES EMBEDDED IN THIS SOUTHERN STREAM FLOW...WEAK SURFACE LOW PRESSURE OFF THE SOUTH CAROLINA COAST. MODEL SOUNDINGS AND SURFACE OBS INDICATE MOISTURE ABOVE 15000 FT...AND LOTS OF LOW LEVEL MOISTURE IN THE AREA THIS AFTERNOON. DRY AIR IN THE MID LEVELS. WITH SHORT WAVES AND RESULTING UPWARD VERTICAL MOTION...SCT LIGHT PRECIP HAS BEEN FALLING ACROSS EASTERN PORTION OF MIDLANDS...WITH RAIN MIXING WITH SLEET...MODERATE SLEET REPORTED IN BAMBERG EARLIER. SURFACE TEMPS ABOVE FREEZING SO NO PROBLEMS. RADAR INDICATING PRECIP MOVING EAST OF REGION. ETA BUFKIT T-SECTIONS SHOW A RETURN OF MOISTURE LATER THIS EVENING...MAINLY BEFORE MIDNIGHT...WITH MID LEVELS BECOMING MORE MOIST...OMEGA NOTED...LOOKS LIKE ANOTHER WEAK SHORT WAVE...WILL KEEP SLIGHT CHANCE POPS IN THE EASTERN MIDLANDS THIS EVENING WITH A MIX OF LIGHT RAIN AND SLEET...IN THE CAE AREA MAY SEE A FEW FLURRIES WITH TEMPERATURE PROFILE ISOTHERMAL...BUT LESS MOISTURE IN THE LOWER TO MID LEVELS. LOOKS LIKE SOME DRIER AIR MOVES INTO AREA SATURDAY...BUT LOW PRESSURE DEVELOPING IN THE GULF OF MEXICO ALONG BAROCLINIC ZONE. UPPER LOW IN MEXICO WILL MOVE EAST-NORTHEAST ALONG GULF COAST AND ACROSS NORTHERN FLORIDA SUNDAY. MODELS SHOW 500MB VORT ADVECTION AFTER MIDNIGHT SUNDAY IN THE EASTERN MIDLANDS/COASTAL SOUTH CAROLINA. SURFACE LOW MOVES ACROSS CENTRAL/SOUTH FLORIDA THEN OFF THE SOUTH CAROLINA COAST EARLY SUNDAY.UPPER LEVEL FORCING LOOKS GOOD THROUGH SUNDAY MORNING...BUT LOW LEVEL MOISTURE LACKING IN THE CAE AREA...DEEPER MOISTURE IN THE OGB AREA. GFS ISENTROPIC LIFT/850MB WARM AIR ADVECTION STRONGER THAN ETA...ALTHOUGH BOTH MODELS FOCUS ADVECTION MAINLY NEAR THE COAST. SURFACE HIGH PRESSURE CENTERED IN NEW ENGLAND WILL BE BUILDING SOUTH ACROSS CAROLINA SUNDAY NIGHT...MAY SET UP COLD AIR DAMMING...SURFACE TEMPS MAY BE COOLER...THAN CURRENT THINKING. PLAN ON CHANCE POPS AT THIS TIME. EXPECT HEAVIER PRECIP EAST OF MIDLANDS. PARTIAL THICKNESS SCHEMES INDICATES A WINTRY PRECIP MIX...WITH RAIN AND SLEET EAST...AND RAIN AND SNOW WEST AND NORTH IN COOLER AIR. INTERESTING THAT GFS HINTS AT FREEZING RAIN PROBLEM WITH SURFACE BELOW 0C. BY SUNDAY AFTERNOON LOW PRESSURE MOVING NORTHEAST AWAY FROM CAROLINA COAST...GFS A LITTLE SLOWER DRYING OUT MID LEVELS THAN ETA. TEMPERATURE FORECAST THIS PERIOD TRICKY...EXPECT CLOUDS TO HOLD TEMPS UP TONIGHT...COLD ADVECTION SATURDAY...THINK LOW 50S TOO OPTIMISTIC...TEMPS SATURDAY NIGHT DEPENDING ON COLD AIR DAMMING... WENT WITH COOLER MAV GUIDANCE SUNDAY WITH CLOUDINESS AND SOME SCATTERED PRECIP...CONSERVATIVE NUMBERS IN THE LOW 40S AT CAE. SUNDAY NIGHT SHOULD BE QUITE COLD IN THE 20S WITH CLEARING SKIES. .LONG TERM... NO MAJOR CHANGES IN EXTENDED PERIOD WITH UPPER RIDGE IN THE SOUTHEAST SLOWLY BUILDING AND MODERATING TEMPERATURES EACH DAY. NO POPS. && .AVIATION... CIGS 2-3 THOUSAND FEET OVER THE AREA LATE THIS AFTERNOON EXTENDING INTO THE EVENING HOURS UNTIL NEAR 02Z. CAE 88D IS PICKING UP LIGHT PRECIP BETWEEN AGS AND OGB WITH DBZ 25-35. PORBABLY SOME LIGHT SLEET. MUCH OF THE PRECIP IS NOT REACHING THE GROUND AS DRY LAYER 850MB-700MB OR 5-10 THOUSAND FEET COVERS THE AREA. LOWER LAYER IS ABOUT 1 THOUSAND FEET DEEP. RUC/MESOETA TIME SECTIONS ARE BRINGING A QUICK SHOT OF MOISTURE IN DRY LAYER THIS AFTERNOON BUT IT DOESN'T LAST VERY LONG. SOME SLEET MAY REACH THE GROUND BUT EXPECT NO WEATHER PROBLEMS FROM THE PRECIP. LOW LAYERS DRY OUT AFTER 02Z WITH JUST MID AND HIGH LEVEL CLOUDS. NO FOG EXPECT CHRISTMAS MORNING. && .PRELIMINARY POINT TEMPS/POPS... COLUMBIA 32 46 30 43 / 10 10 30 30 AUGUSTA 30 46 31 44 / 10 10 40 40 SUMTER 31 46 30 42 / 10 10 30 30 ORANGEBURG 32 46 31 43 / 20 10 40 40 && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ AWP...SHORT TERM/LONG TERM TTH...AVIATION sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 225 PM CST FRI DEC 24 2004 .SYNOPSIS...MORNING ANALYSIS SHOWS A 500 MB PATTERN THAT IS PROGRESSING. THIS IS MOVING THE TROUGH THAT HAS BROUGHT THE ARCTIC AIR INTO THE REGION OFF TO THE EAST. AT THE SURFACE...A RIDGE OF HIGH PRESSURE EXTENDED ALONG THE WESTERN GREAT LAKES. SOUTHWESTERLY FLOW ASSOCIATED WITH WARM ADVECTION WAS LOCATION OVER THE PLAINS AND WESTERN PORTION OF THE UPPER MISSISSIPPI RIVER VALLEY. THIS HAS CAUSED TEMPERATURES TO RISE QUICKLY THIS AFTERNOON ACROSS THAT REGION...WARMING FASTER THAN PREVIOUSLY EXPECTED. LOW PRESSURE WAS CENTERED OVER CENTRAL SOUTH DAKOTA. KRC && .SHORT TERM...CHRISTMAS EVE AND CHRISTMAS DAY MAIN FORECAST PROBLEMS...WILL THE NEXT SYSTEM PRODUCE ENOUGH FORCING TO PRODUCE PRECIPITATION DURING THE PERIOD? AND...TEMPERATURES. SURFACE LOW PRESSURE MOVES SOUTHEAST TONIGHT AND SATURDAY. BY SATURDAY EVENING...IT MOVES INTO NORTHERN ILLINOIS. SOME WEAK FORCING REMAINS ASSOCIATED WITH THE WARM FRONT AS IT NEARS THE FORECAST AREA. THE ETA/GFS/RUC RUNS ARE SIMILAR WITH TIMING AND THE FORCING SIGNALS. THESE FORCING SIGNALS ARE NET ADIABATIC ASCENT ON THE 280K SURFACE AND SOME WEAK 700-500 MB QG CONVERGENCE. THESE MAY BE ENOUGH TO PRODUCE PRECIPITATION. HOWEVER...THE DEWPOINT DEPRESSIONS ARE BETWEEN 10 AND 20 DEGREES UPSTREAM. THEREFORE...WEAK FORCING WILL LIKELY NOT OVERCOME THE DRY AIR UNLESS IT IS PROLONGED. THEREFORE...WILL CONTINUE A CHANCE OF SNOW. REGARDING TEMPERATURES...WARM ADVECTION IN THE BOUNDARY LAYER WILL CONTINUE TEMPERATURE RISES. HOWEVER...THE GRADIENT IS NOT STRONG ENOUGH TO MITIGATE DECOUPLING. THEREFORE...WILL GO FOR A LOW AROUND 3Z. KRC SATURDAY NIGHT THROUGH MONDAY. 12Z 24DEC04 GFS AND ETA IN FAIRLY GOOD AGREEMENT THROUGH THE PERIOD. DIFFERENCES ARISE IN QPF PRODUCTION GIVEN WARM AIR ADVECTION AND ISENTROPIC LIFT ON MONDAY. GIVEN THE DYNAMICS...A BLEND APPROACH SEEMS REASONABLE WITH SMALL CHANCE WORDING. WAVE OF LOW PRESSURE EXITS EAST OF THE AREA BY SATURDAY EVENING...TAKING PRECIPITATION WITH IT. PARTIAL CLEARING LATE WITH COLD AIR ADVECTION WILL ALLOW TEMPERATURES TO DROP INTO THE SINGLE DIGITS BY EARLY SUNDAY MORNING. SUNDAY WILL SEE AN INCREASE IN CLOUDS AS THE DAY WEARS ON. THIS IS IN RESPONSE TO HIGH MOVING OFF TO THE EAST AND WARM AIR ADVECTION/ISENTROPIC LIFT IN ADVANCE OF NEXT CLIPPER SYSTEM. INCREASED ISENTROPIC LIFT (280K SURFACE) ACROSS THE AREA WILL LEAD TO FURTHER SATURATION AND A SMALL CHANCE OF -SN ACROSS NORTHWEST HALF OF FORECAST AREA SUNDAY NIGHT. MAIN LIFT/FORCING SHIFTS INTO NORTHERN WI ON MONDAY WITH FURTHER WARMING ACROSS OUR AREA. WILL CONTINUE A SMALL CHANCE OF -SN...MAINLY NORTH OF A LINE FROM ROCHESTER TO BLACK RIVER FALLS. DAS .LONG TERM...MONDAY NIGHT THROUGH FRIDAY GFS AND ECMWF IN GOOD AGREEMENT WITH DEEPENING UPPER TROUGH OFF THE WEST COAST THROUGH THE PERIOD. THIS IN TURN WILL CAUSE RIDGING OVER THE CENTRAL CONUS FOR A WARMING TREND ACROSS THE REGION. SURFACE HIGH MOVES EAST OF THE AREA MONDAY NIGHT INTO TUESDAY. RETURN FLOW ON BACKSIDE OF THE HIGH AND IN ADVANCE OF ROCKIES LOW WILL START PULLING GULF MOISTURE NORTHWARD INTO THE AREA. FAIRLY GOOD AMOUNT OF MOISTURE/ISENTROPIC LIFT INDICATED ACROSS THE AREA FOR AT LEAST A MENTION OF SNOW MONDAY NIGHT AND A MIX OF RAIN/SNOW ON TUESDAY. NEXT MAJOR WEATHER-MAKER WILL BE LOW MOVING NORTHEAST OUT OF THE ROCKIES THURSDAY NIGHT AND ACROSS THE UPPER MIDWEST ON FRIDAY. WITH MORE NORTHWARD TRACK OF THIS LOW...BUMPED TEMPERATURE UP A TAD. RIGHT NOW...IT APPEARS ENOUGH WARM AIR WILL GET MIXED INTO THE SYSTEM OVER OUR AREA FOR A RAIN/SNOW MIX. && .ARX WATCHES/WARNINGS/ADVISORIES... .WI...NONE. .MN...NONE. .IA...NONE. && $$ DAS wi