AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 900 PM CST SUN DEC 26 2004 .UPDATE... SOME FAIRLY STRONG MID LEVEL SUBSIDENCE IN WAKE OF UPPER TROUGH ACROSS THE EASTERN GREAT LAKES WILL CONTRIBUTE TO SOME DRYING AND WARMING OF THE LOW LEVELS OVERNIGHT WITH SYNOPTIC SCALE WAA KICKING IN TOWARD MORNING AS WINDS CONTINUE TO VEER TO THE SOUTH WITH SURFACE RIDGE AXIS PUSHING EAST OF THE AREA OVERNIGHT. SOME FAVORABLE 850 HPA/LAKE DELTA T'S EARLIER THIS EVENING HAVE BEEN LESSENED IN MAGNITUDE BY PERSISTENT SYNOPTIC SUBSIDENCE WHICH HAS LOWERED INVERSION HEIGHTS TO AOB 4000 FEET PER ACARS/META SOUNDINGS. FETCH ALSO WILL LESSEN THROUGH REMAINDER OF THE EVENING AS LOW LEVEL WINDS CONTINUE TO VEER. WILL HOLD ONTO MENTION OF SOME SCATTERED LIGHT SNOW SHOWERS ACROSS LAKE COUNTY FOR NEXT FEW HOURS. OTHER CONCERN OVERNIGHT IS FOG POTENTIAL MAINLY ACROSS SOUTHERN ZONES WHERE FRESH SNOW COVER WILL AID IN STRONG RADIATIONAL COOLING AND STRONGER LOW LEVEL INVERSION. CURRENT SATELLITE FOG PRODUCT INDICATING SOME RESIDUAL LOW CLOUD FROM EARLIER LAKE EFFECT SNOWS ACROSS FAR SE CWA HELPING TO KEEP SFC DEW POINT DEPRESSIONS UP SOMEWHAT. QUESTION WILL BE IF LOW CLOUDS CAN VACATE BEFORE MID/HIGH LEVEL CLOUD DECK ENTERING WESTERN IL SPREADS EASTWARD WHICH WOULD LIMIT RADIATIONAL COOLING. WILL MONITOR OBS OVER NEXT FEW HOURS AND UPDATE IF TRENDS SUGGEST SOME PATCHY DENSE FOG WILL BE POSSIBLE. OTHERWISE...NO SIGNIFICANT CHANGES ANTICIPATED IN FORECAST FOR THE REST OF THE AREA. NDM .PREVIOUS DISCUSSION FOR AFTERNOON PACKAGE... REMNANTS OF NARROW LAKE EFFECT SNOW BAND ORIENTED NNW-SSE DOWN THE MIDDLE OF THE LAKE. BULK OF THE SNOW NOW BEING DEPOSITED IN BERRIEN AND LAPORTE COUNTIES BUT SNOW BAND GRADUALLY DRIFTING SSW. LAKE EFFECT CLOUDS HAVE GRADUALLY DRIFTED SSW INTO CHICAGO. LATEST RUC INDICATES LIGHT NNW FLOW OVER NRN IL AND STRONGER NNE FLOW DOWN THE LAKE WITH BEST CONVERGENCE ALONG IL SHORE LATER THIS AFTERNOON AND EARLY EVENING. BUT DELTA T FORECAST TO DROP BELOW SIGNIFICANT LAKE EFFECT THRESHOLDS BY AROUND MIDNIGHT. AT THE SAME TIME WINDS SHOULD BECOME LIGHT AND VARIABLE WITH WEAKENING CONVERGENCE. WILL KEEP SCATTERED SNOW SHOWERS WITH LESS THAN AN INCH ACCUMULATION NW IN AND IMMEDIATE IL LAKEFRONT THIS EVENING...DIMINISHING BY ABOUT MIDNIGHT. OTHERWISE TONIGHT MOSTLY CLEAR. WITH FRESH SNOW COVER IN AREAS OF NRN IN AND EAST CENTRAL IL AS SEEN ON VISIBLE SATELLITE...WILL ADJUST LOW TEMPS DOWN OVER SNOW FIELDS...OTHERWISE GUIDANCE TEMPS LOOK REASONABLE. MONDAY THROUGH WEDNESDAY BROAD RIDGING ACROSS MIDDLE OF THE COUNTRY WITH WARM AND DRY WEATHER FOR NRN IL AND IN. A WEAK SHORT WAVE WILL PASS THROUGH THE GREAT LAKES MONDAY NIGHT AND TUESDAY BUT MOISTURE WILL BE LIMITED AND SHOULD STAY MAINLY NORTH OF IL AND IN. BIG STORM OFF CALIFORNIA COAST WILL MOVE INTO PLAINS ABOUT THURSDAY. BIG WARM UP AND A SHOT AT SOME RAIN THURSDAY. GFS INDICATES DRYING OUT FRIDAY AND SATURDAY. ALLSOPP && .AVIATION... FOR 00Z TAFS...WX LOOKING MORE OPTIMISTIC AS EVENING PROGRESSES. LAKE EFFECT SNOW SHOWERS MOVING SOUTH AND REALLY BREAKING UP FAST. MODELS INDICATING THAT WINDS SHUD BACK AROUND FROM NORTH TO EAST...CUTTING OF FETCH OVER WATER AND ELIMINATING SNOW AND EVEN CLOUD ADVECTION OVER TERMINALS BY 04Z. WINDS RATHER LIGHT AND VARIABLE AS SFC RIDGE PASSES THRU TERMINALS OVERNIGHT. ALREADY CAN SEE WAA CIRRUS AND AC ADVECTING EWD ACROSS THE PLAINS. LIKELY TO HAVE AC OVER TERMINALS BY MRNG...BECOMING BKN TO OVC IN THE AFTN. WINDS SHUD BE PICKING UP FROM THE SOUTH AROUND 10 KTS BEFORE NOON MONDAY. DON'T EXPECT CONDS TO DETERIORATE ANY WORSE THRU 00Z. SO SHUD BE A VFR DAY. && .LOT...WATCHES/WARNINGS/ADVISORIES... .IL...NONE .IN...NONE .LK MI...NONE $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 545 PM CST SUN DEC 26 2004 .DISCUSSION... REMNANTS OF NARROW LAKE EFFECT SNOW BAND ORIENTED NNW-SSE DOWN THE MIDDLE OF THE LAKE. BULK OF THE SNOW NOW BEING DEPOSITED IN BERRIEN AND LAPORTE COUNTIES BUT SNOW BAND GRADUALLY DRIFTING SSW. LAKE EFFECT CLOUDS HAVE GRADUALLY DRIFTED SSW INTO CHICAGO. LATEST RUC INDICATES LIGHT NNW FLOW OVER NRN IL AND STRONGER NNE FLOW DOWN THE LAKE WITH BEST CONVERGENCE ALONG IL SHORE LATER THIS AFTERNOON AND EARLY EVENING. BUT DELTA T FORECAST TO DROP BELOW SIGNIFICANT LAKE EFFECT THRESHOLDS BY AROUND MIDNIGHT. AT THE SAME TIME WINDS SHOULD BECOME LIGHT AND VARIABLE WITH WEAKENING CONVERGENCE. WILL KEEP SCATTERED SNOW SHOWERS WITH LESS THAN AN INCH ACCUMULATION NW IN AND IMMEDIATE IL LAKEFRONT THIS EVENING...DIMINISHING BY ABOUT MIDNIGHT. OTHERWISE TONIGHT MOSTLY CLEAR. WITH FRESH SNOW COVER IN AREAS OF NRN IN AND EAST CENTRAL IL AS SEEN ON VISIBLE SATELLITE...WILL ADJUST LOW TEMPS DOWN OVER SNOW FIELDS...OTHERWISE GUIDANCE TEMPS LOOK REASONABLE. MONDAY THROUGH WEDNESDAY BROAD RIDGING ACROSS MIDDLE OF THE COUNTRY WITH WARM AND DRY WEATHER FOR NRN IL AND IN. A WEAK SHORT WAVE WILL PASS THROUGH THE GREAT LAKES MONDAY NIGHT AND TUESDAY BUT MOISTURE WILL BE LIMITED AND SHOULD STAY MAINLY NORTH OF IL AND IN. BIG STORM OFF CALIFORNIA COAST WILL MOVE INTO PLAINS ABOUT THURSDAY. BIG WARM UP AND A SHOT AT SOME RAIN THURSDAY. GFS INDICATES DRYING OUT FRIDAY AND SATURDAY. ALLSOPP && .AVIATION... FOR 00Z TAFS...WX LOOKING MORE OPTIMISTIC AS EVENING PROGRESSES. LAKE EFFECT SNOW SHOWERS MOVING SOUTH AND REALLY BREAKING UP FAST. MODELS INDICATING THAT WINDS SHUD BACK AROUND FROM NORTH TO EAST...CUTTING OF FETCH OVER WATER AND ELIMINATING SNOW AND EVEN CLOUD ADVECTION OVER TERMINALS BY 04Z. WINDS RATHER LIGHT AND VARIABLE AS SFC RIDGE PASSES THRU TERMINALS OVERNIGHT. ALREADY CAN SEE WAA CIRRUS AND AC ADVECTING EWD ACROSS THE PLAINS. LIKELY TO HAVE AC OVER TERMINALS BY MRNG...BECOMING BKN TO OVC IN THE AFTN. WINDS SHUD BE PICKING UP FROM THE SOUTH AROUND 10 KTS BEFORE NOON MONDAY. DON'T EXPECT CONDS TO DETERIORATE ANY WORSE THRU 00Z. SO SHUD BE A VFR DAY. && .LOT...WATCHES/WARNINGS/ADVISORIES... .IL...NONE .IN...NONE .LK MI...NONE $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 1139 AM CST SUN DEC 26 2004 .DISCUSSION... A MOSAIC OF RADAR SITES ALONG LAKE MICHIGAN SHOW A BAND OF SNOW SHOWERS ALONG THE NORTH SOUTH AXIS OF LAKE MICHIGAN. SURFACE STREAMLINE ANALYSIS SHOWS A CYCLONIC CIRCULATION AT THE SOUTHERN END OF THE LAKE AND CONVERGENCE IN THE CENTER NORTH SOUTH AXIS OF THE LAKE. MESOANALYSIS SHOWS A SMALL LOW OVER THE SOUTHEAST CORNER OF LAKE MICHIGAN. THE MESOETA AND WORKSTATION ETA SHOWS THIS CONVERGENCE WILL BE OVER LAKE MICHIGAN THROUGH 00 UTC MONDAY. WILL FORECAST SCATTERED SNOW SHOWERS OVER THE LAKE AND NEAR SHORE TODAY AND TONIGHT. WILL MAKE LITTLE ADJUSTMENTS TO THE HIGH AND LOW TEMPERATURE FORECAST. FOR THE NORTHERN PART OF THE LAKE WILL KEEP A CHANCE OF SNOW MONDAY AND TUESDAY. THE 300 MB WIND FORECAST SHOWS THE JET STREAM OVER THE NORTHERN GREAT LAKES. THERE IS DIVERGENCE ASSOCIATED WITH THE JET 12 UTC TUESDAY. IN THE LONG RANGE...THE GFS90 IS FORECASTING A SHORT WAVE SEEN ON THE 500 MB MOVING INTO THE NORTHERN PLAINS AND NORTHERN GREAT LAKES. WILL KEEP THE CHANCE OF RAIN AND SNOW IN DAY 6. THE MOS GUIDANCE FOR THE WEEK SHOWS THE WARMER AIR MOVING INTO THE FORECAST AREA WITH THE SOUTH WIND AT THE SURFACE BEGINNING ON MONDAY. WHW && .AVIATION... WITH THE EXCEPTION OF KGYY...HAVE GONE WITH A OPTIMISTIC FCST IN TERMS OF CIGS AND VISB. AT THIS TIME IT APPEARS THE LAKE EFFECT CLOUDS AND SN WILL REMAIN EAST OF THE TERMINALS. THIS IS SUPPORTED IN THE NEAR-TERM BY VIS/SFC/88D TRENDS AND THE RUC. IF THE CIGS DUE MOVE WEST INTO THE TERMINALS IFR CONDITIONS WILL DEVELOP AS CIGS AT KRAC HAVE BEEN DOWN TO 800 FEET WITH HAZE. GYY WILL CONTINUE TO SEE MVFR WITH IFR LATER TODAY WIN THE SNOW BANDS THAT HAVE UP TILL THIS POINT REMAINED EAST OF THE AIRPORT. SFC WINDS SHOULD REMAIN OUT OF THE NORTH AND THEN BECOME VARIABLE TONIGHT WITH LIGHT SE FLOW TOMORROW. MID AND HIGH LVL CLOUDS ARRIVE NEAR DAWN ASSOC WITH WAA. && .LOT...WATCHES/WARNINGS/ADVISORIES... .IL...NONE .IN...NONE .LK MI...NONE $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 923 PM MST SUN DEC 26 2004 .DISCUSSION...BASED ON CURRENT TEMPERATURE/DEW POINT SPREADS... DECREASING SURFACE WINDS...AND LATEST RUC OUTPUT...WILL ADD SOME FOG ACROSS THE NORTHEASTERN ZONES LATE TONIGHT AND MONDAY MORNING. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ MENTZER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 1000 AM EST SUN DEC 26 2004 .SHORT TERM (REST OF TODAY THROUGH SUNDAY NIGHT)... WILL ISSUE A WINTER WEATHER ADVISORY FOR SOUTHERN NEW HAMPSHIRE AND YORK COUNTY IN MAINE. ONSHORE FLOW AT 925 MB IS DRIVING AREAS OF SNOW...WITH BANDS OF LIGHT OCEAN EFFECT SNOW MOVING THROUGH THE MAINE FOOTHILLS. 925 MB WINDS ARE PROGGED BY THE ETA/RUC TO PICK UP AND BACK TO MORE OF AN ENE DIRECTION THIS AFTERNOON. EXPECT THIS TO CAUSE AN INCREASE IN SNOW INTENSITY...AND A SOUTHWARD SHIFT IN SNOW BANDS. NO MODEL QPF HAS A HANDLE ON THIS...SO PRETTY MUCH HAVE TO LOOK AT WIND FIELDS FOR THE FORECAST. THE ETA DOES SHOW QPFS IN SOUTHERN NEW HAMPSHIRE THIS AFTERNOON...WHICH IS REASONABLE BASED ON IT'S LOW LEVEL WIND FLOW. HEAVIEST BANDS HAVE BEEN SETTING UP IN THE FOOTHILLS...NOT ALONG THE IMMEDIATE COASTLINE...AS UPSLOPING SEEMS TO BE A KEY FEATURE. UPDATED ZONES RAISING SNOW ACCUMULATIONS FOR THE FOOTHILLS TODAY...AND IN SOUTHERN NEW HAMPSHIRE BASED ON THE ETA WIND FIELD. THERE IS ALREADY HEAVY SNOW REPORTS FROM NORTHERN MASS...SO ISSUED THE ADVISORY NOW BEFORE THE SNOW MOVES IN. KEEPING IN MIND THE CAUSE OF TODAYS SNOW IS COMPLETELY DIFFERENT FROM THE CAUSE OF TONIGHTS SNOWS. WILL RE-EVALUATE TONIGHTS EVENT AS 12Z MODEL DATA COMES IN...BUT AM GENERALLY EXPECTING 1 TO 3 INCHES (HIGHEST ALONG THE IMMEDIATE COASTLINE BASED ON 00Z/06Z RUNS. && LONG TERM (MONDAY THROUGH SATURDAY)... OCEAN STORM EXITS WEEL E OF NEW ENGLAND WITH HIGH PRES SLOWLY BUILDING EWD INTO TUES. SOME WEAK WAA FOR LATE TUES INTO WED WILL BRING CLOUDS AND MAYBE SOME SNWO SHOWERS. HIGH PRES REBUILDS OVER THE AREA FOR LATER IN THE WEEK WITH A WARMING TREND. NO SIG COLD WX OR MAJOR STORMS EXPECTED THRU THE OUTLLOK PERIOD. && .AVIATION...GENERALLY MVFR TO IFR CONDITIONS...BUT VARIABLE BASED ON SNOW BANDS. && MARINE...GALES TO BE HOISTED IN THE SHORT TERM. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...WINTER WEATHER ADVISORY MEZ018-MEZ023. NH...WINTER WEATHER ADVISORY NHZ007>010-NHZ013-014 MARINE...GLW. && $$ UPDATE: APFFEL me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 815 PM EST SUN DEC 26 2004 .DISCUSSION... SFC LOW PRESSURE SYSTEM WHICH BROUGHT HEAVY SNOW TO PORTIONS OF SOUTHEASTERN VA AND LIGHT TO MODERATE SNOWFALL AMOUNTS TO SOUTHEASTERN MD CONTINUES TO PULL AWAY TO THE NORTHEAST AWAY FROM THE MID ATLANTIC COAST. HOWEVER...UPPER LEVEL H5 TROUGH MOVING SOUTHEAST FROM THE CENTRAL AND EASTERN GREAT LAKES REGION IS MOVING TO THE SOUTHEAST THIS EVENING. 21Z RUC SHOWS AREA OF H7 UVV ASSOCIATED WITH THIS SYSTEM WHICH MATCHES UP WELL WITH THE BAND OF SNOW MOVING ACROSS WESTERN AND CENTRAL PA AT 01Z. SMALL BAND OF SNOW FLURRIES HAS DEVELOPED AHEAD OF THE LARGER BAND TO THE NORTH AND IS CROSSING NORTHWESTERN MD...THE EASTERN PANHANDLE OF WV AND FAR NORTHWESTERN ATTM. UPDATED ZONES TO INCLUDE FLURRIES WEST OF THE BLUE RIDGE AS FAR SOUTH AS WARREN COUNTY FOR THIS EVENING. AS H5 TROUGH AXIS MOVES INTO CENTRAL PA JUST BEFORE MIDNIGHT...EXPECT SUBSIDENCE TO SHUT OFF SNOW FLURRY ACTIVITY...EXCEPT IN THE UPSLOPE AREAS TO THE WEST OF THE ALLEGANY FRONT IN ALLEGANY...MINERAL AND GRANT COUNTIES...WHERE A SNOW ADVISORY REMAINS IN EFFECT THROUGH 6 AM EST. UPDATED ZONES NORTH OF WARREN COUNTY AND WEST OF THE BLUE RIDGE TO INCLUDE FLURRIES THIS EVENING. SMITH .PREVIOUS DISCUSSION...240 PM EST... SHORT TERM...TONIGHT AND MONDAY... RADAR CONTINUES TO SUPPORT THE FORECAST REGARDING THE COASTAL SYSTEM AND WITH RELEASE OF THE AFTERNOON PACKAGE WILL REMOVE MENTION OF ANY PRECIP FOR LOWER SRN MD AREA. SERN VA AND THE DELMARVA ARE WERE UNDER THE WINTER GUN TODAY. WHILE THIS NON-EVENT FOR US WAS SOMEWHAT OF A CLOSE CALL ESPECIALLY AFTER TAKING A LOOK AT PNSAKQ REPORTS OF 6-11" OVER HAMPTON ROADS AREA OF VA....THE MODELS LOCKED ONTO A SOLN OVER THE PAST 18 HRS THAT CONSISTENTLY KEPT LWX OUT OF THE PRECIP S AND E OF THE LWX CWA. INTERESTINGLY TODAY'S 06Z GFS SOLN WAS AGAIN OVER-GENEROUS WITH QPF BEING SPREAD TOO FAR N AND W. MEASURABLE 0.01" QPF FROM THE GFS WAS CLOSE TO THE DC/BALT AREAS...THE MODEL UPR DYNAMICS SUPPORTED A DRY FORECAST FOR ALMOST THE ENTIRE CWA. THE 00/06Z ETA WAS MUCH CLOSER TO REALITY IN TERMS OF AREAL QPF COVERAGE. FOR TONIGHT...ONE UPR SHORT WAVE MOVES S OF US AND OFFSHORE WHILE A SECOND WAVE DIVING DOWN ACRS THE CENTRAL GRT LAKES WILL MOVE ACRS PA. ATTM...AM NOT OVERLY IMPRESSED WITH SNOWFALL POTENTIAL IN CURRENT 1-3" SNOW ADVISORY AREA OF WRN MD/ERN WV PNHNDL AREA. LOW LEVEL TRAJECTORIES ARE NOT CONDUCIVE TO THAT AREA SEEING MUCH SNOW...BUT WITH CYCLONIC FLOW AND DECENT CAA WL LEAVE ADVSRY UP AS IS FOR NOW. THINK AMOUNTS WILL BE ON THE LIGHT SIDE THOUGH. OVER THE REMAINDER OF THE AREA FOR TONIGHT...RAPID CLEARING WL OCCUR AFTER MIDNIGHT AFTER PASSAGE OF THE SECOND WAVE. COMBINED WITH THE INTENSIFYING LOW PRES OFF THE DELMARVA COAST TONIGHT...EXPECT THE WINDS TO KICK UP SOME ESPECIALLY OVER THE MARINE AREAS WITH NW-N FLOW. ANOTHER COLD NIGHT WITH A MORE NORTHERLY WIND COMPONENT THERE WILL BE DECENT LOW-LVL CAA WHICH ALLOW TEMPS TO TANK AGAIN TONIGHT. FOR MON...HIGH PRES IN THE OH VALLEY WILL BUILD INTO THE AREA AS THE ATLC SFC LOW DEPARTS TO THE NE. PRES GRAD WILL KEEP WINDS UP THROUGH THE MORNING AND EARLY AFTERNOON...THEN GRADIENT RELAXES AS WINDS WILL BEGIN TO DROP OFF DURING THE AFTERNOON. TEMPS ON MON EVEN UNDER DECENT SUNSHINE WILL STRUGGLE TO REACH FREEZING IN MOST LOCATIONS. AVIATION...CONTINUED VFR THE 070-080 BKN DECK WILL BE OUT OF AFT 03-05Z...THEN CLEARING SKIES. AFTER 13Z/MON EXPECT GUSTY NW WINDS...20-24KT RANGE...TO AFFECT ALL SITES EXCEPT SOMEWHAT LESS AT CHO. .MARINE...SCA ON THE MD BAY AND THE TIDAL POTOMAC. AS THE SFC LOW OFF THE DELMAVRA COAST DEEPENS TONIGHT...WINDS WL INCREASE TO MARGINAL SCA CONDITIONS ON THE TIDAL POTOMAC BY MIDNIGHT. FOR MON DECENT PRES GRADIENT WL CONTINUE SCA ON ALL WATERS THROUGH THE EARLY AFTERNOON. LONG TERM... NOT TOO MUCH HAPPENING UNTIL LATE IN THE WEEK. SFC RDG IS SITUATED OVERHEAD BY 12Z TUE. LGT WINDS AND MCLR SKIES WILL LEAD TO A CHILLY NIGHT MON NGT. GFS DOES HINT AT THE POSSIBILITY OF SOME MID AND HI CLDS LATE...ESPECIALLY W. WAA GETS UNDERWAY TUE. 850 MB TEMPS INCR FM -4C EARLY TUE TO +4C BY 00Z WED. GFS PAINTS QUITE A BIT OF MOISTURE INCR ADVECTION ABV 600 MB. SO WILL HOLD OFF ON WARMING SFC TEMPS UP QUITE THAT MUCH. MAV SEEMS TO HAVE A GOOD HANDLE ON IT. CDFNT DROPS S INTO PA ON WED. LOOKS LIKE IT WON'T MAKE IT INTO OUR CWA. PERHAPS A FEW MORE CLDS...BUT WITH CONT WARMING. TEMPS ABOVE NORMAL ON TUE...INTO THE 50S OVR LRG SXN OF CWA. H5 RDG AXIS OVR FCST AREA LATE THU. AGAIN...ANOTHER DRY DAY WITH TEMPS A BIT ABV NORMAL. GFS HAS DONE A BIT OF A ZIG ZAG REGARDING LATE WEEK FCST BY SPEEDING UP THE ARRIVAL OF A CDFNT. THIS WOULD OBVIOUSLY HAVE BIG IMPLICATIONS ON TEMPS AND PRECIP. HAVE OPTED FOR NO CHG YET PENDING BETTER CONSISTENCY. USED GFSLR FOR SUNDAY FCST...SHOWING FNTL PRECIP OVR AREA AND SFC WAVE RIDING UP THE WRN SIDE OF THE MTNS. TEMPS FCST WARM ENOUGH IN THIS SCENARIO FOR PCPN IT TO BE LIQUID. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...SNOW ADV TNGT MDZ002. VA...NONE. WV...SNOW ADV TNGT WVZ048-049. MARINE...SCA TODAY ANZ530>537. && $$ SHORT TERM/AVIATION...SMZ LONG TERM/MARINE...RDH md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1125 AM EST SUN DEC 26 2004 .SHORT TERM...THIS AFTERNOON... A CLOSE CALL. RADAR TRENDS CONTINUE TO SUPPORT LATEST 12Z ETA/RUC SOLNS THAT THE COASTAL SYSTEM FAR ENOUGH EAST THAT ANY PRECIP...IN THE FORM OF SNOW...WILL BE LIMITED TO PORTIONS OF THE LWX LOWER SRN MD REGION OF ST. MARYS AND CALVERT COUNTIES. HENCE HAVE REMOVED MENTIONED OF SNOW OVER THE DC/BALT METRO REGIONS FOR THIS AFTERNOON BUT LEFT MENTION OF "A FEW FLURRIES" IN THE FORECAST FOR BALT. AND S/E OF DC. THE OTHER NRN STREAM SYSTEM CONTINUES TO LOOK UNIMPRESSIVE ON RADAR AS IT MOVES ACROSS OH/WV. HAVE LEFT IN CURRENT ZFP WORDING FOR SNOW SHOWERS FOR THE FAR WRN TIER OF ZNS...AND ACTUALLY ADDED MENTION OF FLURRIES FOR THE NORTHERN SHENANOAH AND CENTRAL MD. FOR TONIGHT...AM STILL THINKING ABOUT THE SNOW ADVISORY. WL LEAVE AS IS FOR NOW...WITH INITIAL THOUGHTS BEING ANY SNOWFALL AMOUNTS IN THE CURRENT SNOW ADVISORY AREA...ALLEGANY MD AND MINERAL/GRANT CO. IN WV WILL BE ON THE LIGHT SIDE. && .AVIATION...CONTINUED VFR...12Z ETA SHOWS A 060-070 BKN-OVC DECK MOVING THROUGH THE DC/BALT AREAS LATER THIS AFTERNOON. EXPECT SKIES TO BE CLEARING BETWEEN 06-12Z MON. && .MARINE...WL RAISE SCA EVERYWHERE INCLUDING THE TIDAL POTOMAC. AS THE SFC LOW OFF THE DELMAVRA COAST DEEPENS TONIGHT...WINDS WL INCREASE TO MARGINAL SCA CONDTIONS BY MIDNIGHT AT ALL LOCATIONS. && .PREVIOUS LONG TERM (MONDAY AND BEYOND)... MONDAY...NORTHWEST FLOW ALOFT AND NORTH WINDS AT THE SURFACE WILL ENSUE AROUND LOW PRESSURE IN THE ATLANTIC. ETA/GFS ARE EVEN MORE INTREPID WITH COLD ADVECTION ON MONDAY...AND HIGH TEMPERATURES LOOK ABOUT 5-8F BELOW CLIMATOLOGY. WITH COLD ADVECTION AND A 30KT SPEED CORE AT 850 MB...HAVE TRENDED UP WIND SPEEDS...STILL BELOW BREEZY CATEGORY FOR PUBLIC PURPOSES BUT GETTING INTO SMALL CRAFT ADVISORY CRITERIA FOR MARINE PURPOSES. AT NIGHT...COLD ADVECTION WILL CEASE AND 850 MB SPEED CORE WILL DEPART ALLOWING WINDS WILL DIMINISH. TUESDAY/WEDNESDAY...UPPER FLOW BECOMES ZONAL AS SURFACE HIGH PRESSURE OVER THE REGION ON TUESDAY GETS SQUELCHED TO THE SOUTH ON WEDNESDAY WITH A WEAK SURFACE TROUGH/FRONT SKIRTING BY TO OUR NORTH. WITH A LACK OF DYNAMICS AND MOISTURE...NO PRECIP IS EXPECTED WITH SURFACE TROUGH ALTHOUGH AN INCREASE IN CLOUDS IS EXPECTED. MODERATION OF TEMPS WILL BE SLOWER THAN EARLIER ANTICIPATED AND HAVE KNOCKED TUESDAY HIGH TEMPS DOWN A TAD...ALTHOUGH WITH SURFACE HIGH PRESSURE TO OUR SOUTH ON WEDNESDAY...SOUTHWEST FLOW WILL ALLOW FOR A MORE NOTICEABLE WARM UP. THURSDAY THROUGH SATURDAY...FLAT WEST FLOW DEVELOPS MORE OF AN AMPLIFICATION AS UPPER RIDGE OVER THE PLAINS TRANSLATES EAST...NUDGING UP HEIGHTS/THICKNESSES FOR ABOVE CLIMO TEMPS. THE MODELS HAVE BEEN TRENDING SLOWER OVER THE PAST COUPLE OF NIGHTS WITH A COLD FRONT AND CONTINUE TO DO SO. KEPT FORECAST DRY UNTIL SATURDAY WHERE COLD FRONT BRINGS 20 POPS (P-TYPE RAIN) WHICH DONT EVEN MAKE IT INTO THE TEXT PRODUCTS THIS FAR OUT. WOULD NOT EVEN BE SURPRISED IF MODELS TREND SLOWER AND/OR START TO SHOW FRONT NOT TOTALLY MAKING IT THROUGH THE CWA IF A MISSISSIPPI WAVE DEVELOPS ALONG IT OVER THE WEEKEND. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...SNOW ADV TNGT MDZ002. VA...NONE. WV...SNOW ADV TNGT WVZ048-049. MARINE...SCA TODAY ANZ530>534. && $$ SHORT TERM/AVIATION...SMZ MARINE...RDH PREV LONG TERM...PELOQUIN md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 935 PM EST SUN DEC 26 2004 .DISCUSSION... .SHORT TERM... 00Z RAOBS/WV IMAGERY AND RUC ANALYSIS SHOW UPR TROF OVER SE CAN DOWNSTREAM OF A RDG OVER THE PLAINS AND A CLOSED UPR LO OFF THE W COAST. FA UNDER THE INFLUENCE OF A SHRTWV RDG OVER NE MN...BUT ENE FLOW OVER THE FA/LK SUP ON THE SW FLANK OR ARCTIC HI PRES NEAR JAMES BAY GENERATING SOME LES BANDS AS H85 TEMPS ARND 16C AND INVRN HGT STILL AS HI AS H85 PER 00Z APX/GRB SDNGS EVEN THOUGH SUB INVRN AIRMASS IS QUITE DRY. THE MOST INTENSE BAND IS LOCATED ALG THE LK SUP S SHORE FM GRM TO MQT...AND THEN NW TO NR BIG BAY AND THEN TO CMX. THE BAND APPEARS TO BE INTENSIFIED BY THE CNVGC BTWN A NE FLOW OVER THE WATER AND A WEAK LAND BREEZE THAT HAS FORMED WITHIN THE RATHER SLACK PRES GRADIENT. FORTUNATELY...THE BAND IS TENDING TO DRIFT SLOWLY N AS LARGER SCALE FLOW TENDING TO VEER TOWARD THE SE AS HI PRES TO THE NE DRIFTS FARTHER AWAY. MOST INTENSE ECHOES HAVE MOVED OFFSHORE OF MQT COUNTY...BUT IR STLT PIX/CMX OB/SPOTTER REPORT FM LK LINDEN IN CMX COUNTY INDICATES BAND COMING ONSHORE THERE DROPPING SN UP TO AN INCH/HR. OTRW...ANOTHER SHRTWV DROPPING ESE THRU NRN MANITOBA. HI CLD IN THE WAD PATTERN AHEAD OF THIS SYS APRCHG WRN LK SUP AT 02Z...BUT MOST OF THE HI CLD APPEARS TO BE HEADING TOWARD S OF THE FA. SKIES STILL MOCLR OVER THE AREA WITH LLVL DRY AIR IN PLACE. TEMPS HAVE FALLEN WELL BLO ZERO AT A NUMBER OF THE COLDER SPOTS WITH THE LGT WIND. MAIN FCST CONCERNS TNGT ARE LES TRENDS/MIN TEMPS. MOST RECENT MODEL GUIDANCE IN GOOD AGREEMENT SHOWING LARGE SCALE FLOW VEERING S OVERNGT AS ARCTIC HI TO THE NE PROGGED TO CONTINUE MOVING EWD. THINK THESE TRENDS WL KEEP BANDS MOVING N. SO ALTHOUGH LES FALLING STEADILY ON THE E SIDE OF THE KEWEENAW ATTM...WL NOT ISSUE ANY HEADLINES AS BAND SHOULD CONT MOVING STEADILY. ALREADY UPDATED FCST TO MENTION UP TO 4 INCHES AS LK LINDEN SPOTTER ALREADY HAD 2 INCHES THIS EVENING WITH SN STILL FALLING HARD. WITH INCRSG ISENTROPIC LIFT OVERNGT...EXPECT SCT-BKN HI CLD TO DRIFT OVER THE FA DURING THE OVERNGT. IN FACT...MID CLD NOW AS FAR E AS CNTRL MN WILL REACH THE WRN ZNS LATE PER ETA/GFS FCST HIER RH ON THE 290K ISENTROPIC SFC (H65-7). BUT SINCE BULK OF HI CLD ATTM APPEARS TO BE MOVING ON A COURSE TO THE S...EXPECT FVRBL RADIATIONAL COOLING THRU A GOOD PORTION OF THE NGT. LOWERED FCST LO TEMPS SEVERAL DEGREES EARLIER TO AS LO AS 10 BELOW ZERO. SOME PTCHY FOG MAY FORM OVER THE COLDEST LOCATIONS AS TEMP FALLS WELL BLO CURRENT DWPT. KC .LONG TERM... SHORTWAVE WILL WORK BY TO OUR NORTH MONDAY MORNING...WITH SOME INCREASE IN MID-LEVEL MOISTURE THROUGH THE MORNING HOURS. LOW LEVEL MOISTURE RETURN LOOKS LIKE IT WILL LAG THE MID-LEVEL MOISTURE...AND THINGS DON/T REALLY LOOK LIKE THEY WILL MOISTEN UP IN THE LOW LEVELS UNTIL LATER IN THE DAY. AT THAT POINT...THERE IS STILL SOMEWHAT DEEP MOISTURE IN PLACE ALONG WITH SOME WEAK 850-500MB Q-VECTOR CONVERGENCE. GIVEN THE DEPTH OF MOISTURE AND EXPECTED WEAK FORCING...AN AREA OF LIGHT SNOW WILL PROBABLY MANAGE TO WORK ACROSS THE AREA FROM MONDAY AFTERNOON INTO MONDAY EVENING. LOW LEVEL MOISTURE WILL THEN LINGER OVER THE AREA INTO TUESDAY...WHEN SHORTWAVE ENERGY EJECTING FROM THE WESTERN US TROUGH MOVES EAST TOWARD THE REGION. THIS SHORTWAVE WILL PUSH A COLD FRONT THROUGH THE AREA ON TUESDAY-TUESDAY EVENING...WITH SOME DPVA AND WAA AHEAD OF IT. WILL MENTION LIKELY LIGHT SNOW AS THIS WORKS THROUGH THE AREA...AND ALLOW FOR SOME LAKE EFFECT SNOW SHOWERS TUESDAY NIGHT WITH MARGINALLY COLD BOUNDARY LAYER TEMPERATURES AND LINGERING MOISTURE AND CYCLONIC FLOW. PREFER THE SLIGHTLY COLDER BOUNDARY LAYER TEMPERATURES SHOWN BY THE GFS...ALTHOUGH IF THE ETA WERE TO VERIFY LATER SHIFTS MAY NEED TO EVALUATE POTENTIAL FOR SOME POST-FROPA FREEZING DRIZZLE. RIDGING BUILDS INTO THE AREA ON WEDNESDAY...WITH FAIRLY DECENT HEIGHT RISES AND INCREASING 925-700MB TEMPERATURES. ATTENTION WILL THEN TURN TOWARD THE SYSTEM EXPECTED TO IMPACT THE AREA FOR THE SECOND HALF OF THE WEEK. EXPECT A FAIRLY SIGNIFICANT SHORTWAVE TO EJECT NORTHEAST FROM THE WESTERN TROUGH AND WORK ITS WAY TOWARD THE REGION ON THURSDAY. GOOD WAA AND MOISTURE RETURN SHOULD BRING THE CHANCE FOR SOME PCPN INTO THE CWFA FROM SOUTHWEST TO NORTHEAST THURSDAY. ALTHOUGH THE PCPN MAY INITIALLY BE SNOW...FORECAST TEMPERATURES FROM THE GFS...ECMWF...AND CANADIAN MODELS SUPPORT A QUICK CHANGEOVER TO RAIN BY THURSDAY NIGHT. WILL MENTION A CHANCE OF RAIN/SNOW THURSDAY TO ACCOUNT FOR THE EXPECTED EVOLUTION FROM SNOW-RAIN...BUT WILL NOT TRY TO PIN DOWN ANY DETAILS AT THIS POINT. THE MEDIUM RANGE GUIDANCE IS ACTUALLY IN FAIRLY GOOD AGREEMENT ON THE LARGE SCALE FLOW PATTERN FROM THE END OF THE WEEK THROUGH THE WEEKEND. TROUGHING IS PROGGED TO PERSIST OVER WESTERN NORTH AMERICA...WITH SHORTWAVES PERIODICALLY LIFTING NORTHEAST FROM THE LONGWAVE TROUGH TOWARD OUR AREA. THERE IS SOME DISAGREEMENT ON THE TIMING AND AMPLITUDE OF THESE SHORTWAVES...BUT THE DIFFERENCES ARE NOT SUBSTANTIAL. IN GENERAL...THE ECMWF IS MORE AMPLIFIED WITH THE UPPER TROUGH OVER WESTERN NORTH AMERICA IN COMPARISON TO THE 00Z GFS. THE CANADIAN IS MORE SIMILAR TO THE ECMWF...AND WITH THE MORE AMPLIFIED PATTERN BOTH THE ECMWF AND CANADIAN EJECT SHORTWAVES WHICH ARE SLIGHTLY MORE INTENSE DURING THE PERIOD. THE GFS ENSEMBLES SUPPORT ITS SOMEWHAT LESS AMPLIFIED SOLUTION. GIVEN THE HIGHLY AMPLIFIED FLOW CURRENTLY IN PLACE OFF THE WEST COAST...SEE NO REASON WHY THE ARRIVAL OF REINFORCING SHORTWAVE ENERGY WILL NOT CONTINUE TO KEEP A DEEP TROUGH IN PLACE ALONG THE WEST COAST DURING THE EXTENDED PERIOD. WILL ESSENTIALLY GO WITH A BLEND OF THE GFS...ECMWF...AND CANADIAN SOLUTIONS...WHICH IN THE LARGE PICTURE ARE FAIRLY SIMILAR TO ONE ANOTHER. EXPECT SHORTWAVE AND ASSOCIATED SURFACE LOW TO LIFT NORTHEAST FROM THE CENTRAL PLAINS LATE THURSDAY...AND MOVE ACROSS THE UPPER GREAT LAKES EARLY FRIDAY. THERE WILL BE A DECENT WARM-UP AHEAD OF THIS FEATURE...ALTHOUGH WITH DEEP SNOW COVER IN PLACE AND THE SURFACE LOW LIKELY TRACKING VERY CLOSE TO LAKE SUPERIOR...AM NOT EXPECTING OVERWHELMINGLY WARM READINGS. WILL CONTINUE TO MENTION A CHANCE OF RAIN/SNOW OVER THE NORTHERN CWFA...BUT WILL JUST GO WITH A CHANCE OF RAIN OVER THE SOUTH THROUGH EARLY FRIDAY GIVEN THE EXPECTED 850MB TEMPERATURES AND THE CONSISTENCY OF THE MODEL GUIDANCE WITH REGARD TO THIS FEATURE. COOLER TEMPERATURES SHOULD FILTER IN BEHIND THE LOW BY FRIDAY NIGHT...WHICH WILL ALLOW FOR ANY LINGERING PCPN TO CHANGE TO SNOW. THERE APPEARS TO BE A BRIEF WINDOW ON SATURDAY FOR SOME LAKE EFFECT SNOW SHOWERS...WITH SOME LINGERING CYCLONIC FLOW AND 850MB TEMPERATURES OF -10C TO -15C. RIDGING LOOKS LIKE IT WILL BUILD INTO THE REGION SATURDAY NIGHT INTO EARLY SUNDAY...WHICH SHOULD WORK TO KILL OFF MOST OF THE SNOW SHOWER ACTIVITY. HOWEVER...WITH THE SURFACE HIGH TO OUR NORTH...SOME ONSHORE FLOW AND SNOW FLURRIES ARE STILL POSSIBLE. ANOTHER SHORTWAVE WILL BEGIN TO LIFT NORTHEAST TOWARD THE AREA LATE SUNDAY...AND THE GFS TRACKS AN ASSOCIATED SURFACE LOW INTO LOWER MICHIGAN BY MONDAY MORNING WHILE INCREASING MID LEVEL MOISTURE OVER OUR AREA. WILL BRING A CHANCE OF SNOW BACK INTO THE ENTIRE CWFA BY LATE SUNDAY TO ACCOUNT FOR THE POTENTIAL FOR SOME SNOW FROM THIS FEATURE. TRH && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 318 PM EST SUN DEC 26 2004 .DISCUSSION... THE MAIN SHORT TERM CONCERN IS THE LINGERING LES THIS EVENING...THEN ATTENTION TURNS TOWARD A SHORTWAVE AND SURFACE TROUGH HEADING BY TO OUR NORTH EARLY MONDAY AND A SHORTWAVE AND COLD FRONT WHICH MOVE THROUGH THE CWFA LATE TUESDAY. LATEST WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES SHOW AMPLIFIED FLOW OVER THE CONUS...WITH AN UPPER LOW OFF THE WEST COAST...RIDGING OVER THE ROCKIES...AND THE TROUGH CURRENTLY SHIFTING EAST OUT OF OUR AREA. SHORTWAVE WHICH CAN BE SEEN DIGGING INTO NORTHERN MANITOBA WILL SWING BY TO OUR NORTH LATE TONIGHT/EARLY MONDAY. THIS FEATURE WILL HAVE A MINIMAL DIRECT IMPACT ON THE FORECAST AREA...OTHER THAN TO MOISTEN THE MID-LEVELS A BIT. THE 12Z GFS AND ETA ARE SIMILAR THROUGH THE FORECAST PERIOD...AND WILL GENERALLY UTILIZE A BLEND OF THEIR GUIDANCE. THE GFS IS A BIT SLOWER WITH THE EASTWARD PROGRESSION OF THE COLD FRONT ON TUESDAY...BUT THE OVERALL DIFFERENCES ARE MINIMAL. LATEST VISIBLE SATELLITE AND 88D IMAGERY CONTINUE TO SHOW GOOD LES BANDING ON LAKE SUPERIOR...WITH GENERALLY EAST-WEST BANDS OVER EASTERN LAKE SUPERIOR AND NORTHEAST-SOUTHWEST BANDS OVER THE WEST. THE MESOLOW WHICH HAS PLAGUED MARQUETTE COUNTY FOR THE PAST 18-24 HOURS HAS ESSENTIALLY LOST ITS IDENTITY...AND THE LACK OF ADDITIONAL ONSHORE FLOW PREVIOUSLY PROVIDED BY IT HAS RESULTED IN MOST OF THE LES ACTIVITY STALLING JUST OFFSHORE OF MARQUETTE COUNTY. THE ONSHORE FLOW NO LONGER APPEARS SUFFICIENT TO ADVECT THE PCPN UP THE HIGHER TOPOGRAPHY OF MARQUETTE COUNTY...AND SOME OF THE ACTIVITY IS SPILLING INTO THE LOWER TERRAIN TO THE WEST AND EAST...IN KEWEENAW BAY AND INTO LOCATIONS EAST OF HARVEY. CURIOUSLY...SOME OF THE BOUNDARY LAYER MOISTURE ABOVE 1000FT APPEARS TO BE ADVECTING INLAND...HELPING TO DEVELOP SOME LIGHT SNOW SHOWERS FROM THE AXIS OF HIGHER TERRAIN INLAND OVER BARAGE AND NORTHEAST IRON COUNTIES. CONVERGENCE ALONG THE SHORELINE WILL LIKELY PERSIST INTO THE EVENING HOURS...BUT MOST OF THE HEAVIER LES SHOULD CONTINUE TO REMAIN OFFSHORE. THE EXCEPTIONS FOR THE NEXT SEVERAL HOURS WILL BE LOCATIONS ALONG THE WEST SIDE OF KEWEENAW BAY AND AREAS NEAR SHOT POINT AND LAUGHING WHITEFISH POINT. THOSE LOCATIONS COULD STILL PICK UP A FEW ADDITIONAL INCHES OF SNOWFALL THROUGH EARLY EVENING BEFORE CONDITIONS FOR LES BECOME MUCH LESS FAVORABLE. THE 12Z ETA AND WSETA BOTH SHOW THE BOUNDARY LAYER MOISTURE DECREASING SUBSTANTIALLY DURING THE EARLY EVENING AS SHORTWAVE RIDGING AND SUBSIDENCE WORK IN AND THE INVERSION LOWERS. IN ADDITION...SYNOPTIC SCALE SOUTHERLY FLOW SHOULD FINALLY BECOME SUFFICIENTLY STRONG BY LATE EVENING TO PUSH ANY LINGERING LES OUT INTO LAKE SUPERIOR. WITH ONLY A FEW ADDITIONAL INCHES OF SNOW EXPECTED...WILL ALLOW HEADLINES TO EXPIRE WITH THIS FORECAST ISSUANCE...BUT WILL CONTINUE TO MENTION THE POSSIBILITY OF BRIEFLY HEAVY SNOW SHOWERS EARLY THIS EVENING. RETURN FLOW WILL SETUP BY LATE EVENING...WITH WAA FROM THE SURFACE THROUGH 700MB. SHORTWAVE WILL WORK BY TO OUR NORTH MONDAY MORNING...WITH SOME INCREASE IN MID-LEVEL MOISTURE THROUGH THE MORNING HOURS. LOW LEVEL MOISTURE RETURN LOOKS LIKE IT WILL LAG THE MID-LEVEL MOISTURE...AND THINGS DON/T REALLY LOOK LIKE THEY WILL MOISTEN UP IN THE LOW LEVELS UNTIL LATER IN THE DAY. AT THAT POINT...THERE IS STILL SOMEWHAT DEEP MOISTURE IN PLACE ALONG WITH SOME WEAK 850-500MB Q-VECTOR CONVERGENCE. GIVEN THE DEPTH OF MOISTURE AND EXPECTED WEAK FORCING...AN AREA OF LIGHT SNOW WILL PROBABLY MANAGE TO WORK ACROSS THE AREA FROM MONDAY AFTERNOON INTO MONDAY EVENING. LOW LEVEL MOISTURE WILL THEN LINGER OVER THE AREA INTO TUESDAY...WHEN SHORTWAVE ENERGY EJECTING FROM THE WESTERN US TROUGH MOVES EAST TOWARD THE REGION. THIS SHORTWAVE WILL PUSH A COLD FRONT THROUGH THE AREA ON TUESDAY-TUESDAY EVENING...WITH SOME DPVA AND WAA AHEAD OF IT. WILL MENTION LIKELY LIGHT SNOW AS THIS WORKS THROUGH THE AREA...AND ALLOW FOR SOME LAKE EFFECT SNOW SHOWERS TUESDAY NIGHT WITH MARGINALLY COLD BOUNDARY LAYER TEMPERATURES AND LINGERING MOISTURE AND CYCLONIC FLOW. PREFER THE SLIGHTLY COLDER BOUNDARY LAYER TEMPERATURES SHOWN BY THE GFS...ALTHOUGH IF THE ETA WERE TO VERIFY LATER SHIFTS MAY NEED TO EVALUATE POTENTIAL FOR SOME POST-FROPA FREEZING DRIZZLE. RIDGING BUILDS INTO THE AREA ON WEDNESDAY...WITH FAIRLY DECENT HEIGHT RISES AND INCREASING 925-700MB TEMPERATURES. ATTENTION WILL THEN TURN TOWARD THE SYSTEM EXPECTED TO IMPACT THE AREA FOR THE SECOND HALF OF THE WEEK. EXPECT A FAIRLY SIGNIFICANT SHORTWAVE TO EJECT NORTHEAST FROM THE WESTERN TROUGH AND WORK ITS WAY TOWARD THE REGION ON THURSDAY. GOOD WAA AND MOISTURE RETURN SHOULD BRING THE CHANCE FOR SOME PCPN INTO THE CWFA FROM SOUTHWEST TO NORTHEAST THURSDAY. ALTHOUGH THE PCPN MAY INITIALLY BE SNOW...FORECAST TEMPERATURES FROM THE GFS...ECMWF...AND CANADIAN MODELS SUPPORT A QUICK CHANGEOVER TO RAIN BY THURSDAY NIGHT. WILL MENTION A CHANCE OF RAIN/SNOW THURSDAY TO ACCOUNT FOR THE EXPECTED EVOLUTION FROM SNOW-RAIN...BUT WILL NOT TRY TO PIN DOWN ANY DETAILS AT THIS POINT. THE MEDIUM RANGE GUIDANCE IS ACTUALLY IN FAIRLY GOOD AGREEMENT ON THE LARGE SCALE FLOW PATTERN FROM THE END OF THE WEEK THROUGH THE WEEKEND. TROUGHING IS PROGGED TO PERSIST OVER WESTERN NORTH AMERICA...WITH SHORTWAVES PERIODICALLY LIFTING NORTHEAST FROM THE LONGWAVE TROUGH TOWARD OUR AREA. THERE IS SOME DISAGREEMENT ON THE TIMING AND AMPLITUDE OF THESE SHORTWAVES...BUT THE DIFFERENCES ARE NOT SUBSTANTIAL. IN GENERAL...THE ECMWF IS MORE AMPLIFIED WITH THE UPPER TROUGH OVER WESTERN NORTH AMERICA IN COMPARISON TO THE 00Z GFS. THE CANADIAN IS MORE SIMILAR TO THE ECMWF...AND WITH THE MORE AMPLIFIED PATTERN BOTH THE ECMWF AND CANADIAN EJECT SHORTWAVES WHICH ARE SLIGHTLY MORE INTENSE DURING THE PERIOD. THE GFS ENSEMBLES SUPPORT ITS SOMEWHAT LESS AMPLIFIED SOLUTION. GIVEN THE HIGHLY AMPLIFIED FLOW CURRENTLY IN PLACE OFF THE WEST COAST...SEE NO REASON WHY THE ARRIVAL OF REINFORCING SHORTWAVE ENERGY WILL NOT CONTINUE TO KEEP A DEEP TROUGH IN PLACE ALONG THE WEST COAST DURING THE EXTENDED PERIOD. WILL ESSENTIALLY GO WITH A BLEND OF THE GFS...ECMWF...AND CANADIAN SOLUTIONS...WHICH IN THE LARGE PICTURE ARE FAIRLY SIMILAR TO ONE ANOTHER. EXPECT SHORTWAVE AND ASSOCIATED SURFACE LOW TO LIFT NORTHEAST FROM THE CENTRAL PLAINS LATE THURSDAY...AND MOVE ACROSS THE UPPER GREAT LAKES EARLY FRIDAY. THERE WILL BE A DECENT WARM-UP AHEAD OF THIS FEATURE...ALTHOUGH WITH DEEP SNOW COVER IN PLACE AND THE SURFACE LOW LIKELY TRACKING VERY CLOSE TO LAKE SUPERIOR...AM NOT EXPECTING OVERWHELMINGLY WARM READINGS. WILL CONTINUE TO MENTION A CHANCE OF RAIN/SNOW OVER THE NORTHERN CWFA...BUT WILL JUST GO WITH A CHANCE OF RAIN OVER THE SOUTH THROUGH EARLY FRIDAY GIVEN THE EXPECTED 850MB TEMPERATURES AND THE CONSISTENCY OF THE MODEL GUIDANCE WITH REGARD TO THIS FEATURE. COOLER TEMPERATURES SHOULD FILTER IN BEHIND THE LOW BY FRIDAY NIGHT...WHICH WILL ALLOW FOR ANY LINGERING PCPN TO CHANGE TO SNOW. THERE APPEARS TO BE A BRIEF WINDOW ON SATURDAY FOR SOME LAKE EFFECT SNOW SHOWERS...WITH SOME LINGERING CYCLONIC FLOW AND 850MB TEMPERATURES OF -10C TO -15C. RIDGING LOOKS LIKE IT WILL BUILD INTO THE REGION SATURDAY NIGHT INTO EARLY SUNDAY...WHICH SHOULD WORK TO KILL OFF MOST OF THE SNOW SHOWER ACTIVITY. HOWEVER...WITH THE SURFACE HIGH TO OUR NORTH...SOME ONSHORE FLOW AND SNOW FLURRIES ARE STILL POSSIBLE. ANOTHER SHORTWAVE WILL BEGIN TO LIFT NORTHEAST TOWARD THE AREA LATE SUNDAY...AND THE GFS TRACKS AN ASSOCIATED SURFACE LOW INTO LOWER MICHIGAN BY MONDAY MORNING WHILE INCREASING MID LEVEL MOISTURE OVER OUR AREA. WILL BRING A CHANCE OF SNOW BACK INTO THE ENTIRE CWFA BY LATE SUNDAY TO ACCOUNT FOR THE POTENTIAL FOR SOME SNOW FROM THIS FEATURE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ TRH mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1135 AM EST SUN DEC 26 2004 .DISCUSSION... MAIN CONCERNS WITH THIS UPDATE ARE CONTINING SNOWFALL OVER THE HIGHER TERRAIN AREAS OF MARQUETTE/BARAGA COUNTIES. KMQT 88D RADAR SHOWS INTENSE LAKE EFFECT SNOW BAND CONTINUING TO MOVE ONSHORE NEAR BIG BAY...WITH REFLECTIVITIES REACHING INTO THE HIGHER TERRAIN AREAS OF MARQUETTE/BARAGA COUNTIES. CURRENT WINDS ACROSS EASTERN LAKE SUPERIOR ARE FROM THE NORTHEAST...WITH A GRADUAL VEERING TO THE EAST TOWARDS WHITEFISH BAY. RUC13 WINDS...EVEN THE PRECIP FIELD...MATCH UP PRETTY WELL WITH THE CURRENT OBS AND DEPICT THE WINDS ACROSS EASTERN LAKE SUPERIOR DECREASING AND VEERING TO THE EAST BY THIS AFTERNOON...AND BECOMING SOUTHEAST BY THIS EVENING. THIS WILL ALLOW THE SNOW BAND TO CONTINUE IMPACTING MARQUETTE COUNTY...ESPECIALLY THE NEARSHORE AREAS FROM MARQUETTE TOWARD BIG BAY. THE LAKE EFFECT SNOW WARNING FOR MARQUETTE COUNTY WILL BE EXTENDED UNTIL 4PM THIS AFTERNOON TO ACCOUNT FOR THE ADDITIONAL SNOWFALL ACCUMULATIONS...AND THE REDUCED VISIBILITY WITHIN THE SNOWBAND. SPOTTER REPORTS INDICATE SNOWFALL RATES ON THE ORDER OF A FEW INCHES IN AN HOUR. ELSEWHRE ACROSS THE CWA...ONLY LIGHT TO MODERATE SNOW SHOWERS ARE OCCURING AS DEPICTED BY SURFACE OBSERVATIONS AND VISIBLE SATELLITE IMAGERY. THE BEST SNOWFALL ACCUMULATIONS WILL BE LIMITED TO NEAR LAKE SUPERIOR THIS AFTERNOON AS LIGHT WINDS ARE KEEPING THE BANDS FROM PUSHING INLAND. A FEW FLURRIES ARE POSSIBLE EARLY THIS AFTERNOON...BUT EXPECT PARTLY TO MOSTLY SUNNY SKIES TO DOMINATE. THE REST OF FORECAST PACKAGE LOOKS ON TRACK WITH ONLY MINOR ADJUSTMENTS MADE TO THE WINDS AND SKY COVER. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING UNTIL 4 PM EST MIZ005. && $$ LAROSA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 930 PM EST SUN DEC 26 2004 .SHORT TERM (TNGT - MONDAY)... LATEST RADAR TRENDS INDICATE THAT A BAND OF SIGNIFICANT SNOW IS DEVELOPING FROM OTSEGO COUNTY SOUTHWEST TO EASTERN SUSQUEHANNA COUNTY. 18Z ETA... RUC... AND NOW THE 00Z ETA HAVE ALL BEEN INDICATING THAT A BAND OF SNOW WOULD DEVELOP SOMEWHERE NEAR THAT AREA THIS EVENING... IN RESPONSE TO LARGE SCALE LIFT ASSOCIATED WITH A STRONG VORT MAX MOVING SOUTHEAST ACROSS PA... FOCUSED BY MID-LEVEL FRONTOGENESIS. MOISTURE WILL BE LIMITED... AS THE MAIN PRECIPIATION BAND WITH THIS SYSTEM WILL BE OVER NEW ENGLAND IN ASSOCIATION WITH THE COASTAL STORM. HOWEVER... STILL EXPECT A BAND OF 1 TO 3 INCHES OVER THE WESTERN CATKSILLS AND EXTREME NE PA. OUTSIDE OF THIS BAND... SNOW WILL BE LIGHT... AN INCH OR LESS. SNOW WILL TAPER OFF LATER TONIGHT... BUT SOME MULTIBAND LAKE EFFECT WILL PROBABLY DEVELOP FOR AWHILE LATE TONIGHT AND MONDAY MORNING WITH 320 FLOW AND GRADUALLY FALLING INVERSION. LOOKS LIKE ENOUGH LOW-LEVEL MOISTURE AND ENOUGH OF A SNOW GROWTH ZONE FOR SOME LIGHT ACCUMLUATIONS ACROSS A LARGE AREA INTO MONDAY MORNING. ACTIVITY WILL TAPER OFF MONDAY AFTERNOON AS THE SFC HIGH BUILDS EAST. && .LONG TERM...(MONDAY NIGHT-SUNDAY) SEVERAL WEAK SHORTWAVES WILL MOVE THROUGH TUESDAY AND WEDNESDAY... WHICH SHOULD GENERATE A FEW SNOW SHOWERS. THU WILL BE DRY AND WARMER AS HIGH PRESSURE MOVES INTO THE WRN ATLANTIC AND WINDS BECOME SOUTHWEST ACROSS OUR AREA. SHORTWAVE ENERGY EJECTING OUT OF THE SOUTHWEST U.S. WILL BRING A CHANCE OF RAIN FRIDAY. SAT LOOKS DRY AND MILD. COLDER WEATHER RETURNS ON SUNDAY AS AN ARCTIC COLD FRONT MOVES THROUGH. THE GFS HAS BEEN TRENDING WEAKER WITH THE WRN RIDGE AND FARTHER WEST WITH NRN STREAM TROUGHING OVER ERN CANADA...SO IT LOOKS LIKE WE MAY ENTER INTO A COLDER PATTERN ONCE THE ARCTIC AIR MOVES IN AT THE END OF NEXT WEEK.. && .AVIATION...(26/18Z-27/18Z) VFR CONDITIONS WILL DETERIORATE TO MVFR/IFR BETWEEN 22Z-02Z AS SNOW MOVES INTO THE AREA. CONDITIONS SHOULD IMPROVE TO VFR AT KELM AFTER 12Z...BUT SNOW SHOWERS AND LOW CLOUDS SHOULD KEEP MVFR CONDITIONS AT ALL OTHER TAF SITES THROUGH 18Z MONDAY. && .BGM WATCHES/WARNINGS/ADVISORIES... .NY...NONE. .PA...NONE. && $$ MSE ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ALBANY NY 858 PM EST SUN DEC 26 2004 .SHORT TERM (REST OF TONIGHT)... LOT'S HAPPENING OVER THE NORTHEAST ON THE 0130Z SFC MAP. LOW PRESSURE WELL SOUTHEAST OF LONG ISLAND/CAPE COD CONTINUES TO DEEPEN AND INTENSIFY AND MOVE SLOWLY NORTHEAST. A STRONG H500 VORT MAX/TROUGH CONTINUES TO DIG AND PIVOT TO A NEGATIVELY TILTED ORIENTATION OVER EASTERN LAKES ERIE AND ONTARIO VIA THE LATEST 40KM RUC OUTPUT. THE IR PICTURE BEAUTIFULLY SHOWS A COMMON HEAD WITH GOOD DEFORMATION FORMING OVER ERN NY AND NEW ENGLAND. LATEST ETA 40KM RUN SHOWS A GOOD 850/700 TOTAL DEF ZONE DEVELOPING OVER THE HUDSON RIVER VALLEY AND CNTRL NY AROUND 03Z TO 06Z AND CONTINUING UNTIL ABOUT 09Z OR SO. STRONG UPWARD VERTICAL MOTION ASSOCIATED WITH DEF ZONES WITH WEAK FRONTOGENESIS. THE LATEST KENX LOCAL RADAR AND THE NY/NEW ENGLAND RADAR SHOWS A GOOD N-S BAND FORMATION(S) OVER ERN NY IN THE VICINITY OF THE HUDSON RIVER VALLEY AND ONE OVER CNTRL NY. BASED ON THE LATEST RADAR TRENDS AND THE SHORT RANGE MESOSCALE MODELS...IT APPEARS A 2-4" (ERN CATSKILLS/SRN ADIRONDACKS) OR 1-3" (HUDSON RIVER VALLEY) SNOWFALL IS ON TRACK. MOST LOCATIONS HAVE RECEIVED 0.25"-0.5" IN EXTREME ERN NY...WITH THE ERN CATSKILLS GETTING AROUND 1-1.5" THUS FAR. WRN NEW ENGLAND HAS SEEN VERY LITTLE SO FAR. HAVE UPPED THE POPS TO CATEGORICAL VALUES AND INCREASED THE SNOW ACCUMULATION RANGE TO 2-4" BASED GROUND TRUTH REPORTS/RADAR TRENDS. ALSO UPDATED TEMP/DWPT/WIND TRENDS BASED ON OBS. NEW ZONES BY 915 PM. && .AVIATION... CONDITIONS WILL REMAIN MVFR OVERNIGHT AND OCCASIONALLY DROP TO IFR IN THE HUDSON RIVER VALLEY IN THE SNOWFALL. EXPECT CONDITIONS TO IMPROVE TO VFR LEVELS BTWN 14Z AND 17Z WITH BRISK N/NW WINDS AT 10 TO 20 KNOTS WITH SOME GUSTS UP TO 25 KNOTS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NY...NONE. VT...NONE. && && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 247 PM EST SUN DEC 26 2004 .SHORT TERM (TONIGHT THROUGH TUESDAY NIGHT)... UPPER TROUGH WILL CROSS EASTERN NEW YORK AND WESTERN NEW ENGLAND THIS AFTERNOON AND TONIGHT BUT SOUTHERN PORTION IS AHEAD OF MAIN AXIS WHICH WILL BE OVER THE HUDSON VALLEY AROUND 12Z MONDAY. THEN NORTHWEST FLOW WILL PERSIST UNTIL 18Z TUESDAY WHEN FLOW BACKS TO WESTERLY. AT THE SURFACE AN ELONGATED LOW OFF THE SOUTHEAST ATLANTIC COAST WILL INTENSIFY AS IT LIFTS NORTHEASTWARD BUT IT WILL BE WELL OUT TO SEA. SO PRECIPITATION ASSOCIATED WITH IT WILL BE RELATIVELY LIGHT. HIGH PRESSURE WILL FOLLOW MONDAY/TUESDAY THEN SLIDE SOUTHEASTWARD ALLOWING NEXT WEAK FRONTAL SYSTEM TO APPROACH THE SAINT LAWRENCE VALLEY. EXPECTING SNOWFALL TO BE ON THE ORDER OF 1 TO 3 INCHES TONIGHT. && .LONG TERM (WEDNESDAY THROUGH SUNDAY)... .LONG RANGE (WEDNESDAY THROUGH SUNDAY)...MODERATING WEATHER THROUGH THE PERIOD WITH ONE AREA OF LOW PRESSURE TO DEAL WITH. SNOW SHOWERS MAY LINGER INTO WEDNESDAY AS LOW DEPARTING EASTERN CANADA DROPS COLD FRONT INTO NORTHERN BORDER AREAS. FRONT DROPS INTO AREA AND THEN WASHES OUT AS ARCTIC HIGH TO THE NORTH BRIDGES WITH HIGH TO SOUTH. REAL COLD AIR REMAINS TO NORTH WITH H8 TEMPERATURES ONLY DROPPING TO -6/-8 RANGE. FLOW INITIALLY FAVORABLE FOR SOME LAKE INFLUENCE BUT AIR/LAKE TEMP DIFFERENTIAL ONLY REACHES ABOUT 10-11C. DURING THE WEDNESDAY NIGHT FLOW BECOMES MORE SHEARED. MIXED LAYER SHALLOW SO NOT MUCH MORE THAN FLURRIES OR LOW POP SNOW SHOWERS WITH EMPHASIS ON NORTH AND WEST. NEXT SYSTEM OF CONSEQUENCE TO AFFECT THE REGION WILL COME FRIDAY AND/OR SATURDAY. NOT REAL IMPRESSIVE THOUGH AS UPPER TROUGH MINORING OUT AS MOVES INTO EASTERN NORTH AMERICA. THICKNESSES SUPPORTS MAINLY RAIN EVENT. HAVE CONTINUED ZR- MENTION BUT SCALED BACK BASED ON FORECAST THICKNESSES. TIMING BROAD BRUSHED (FRIDAY INTO SATURDAY) THOUGH GFS SUGGEST DURATION NOT EXTENSIVE...WITH ONE QUICK SHOT FRIDAY IN WARM ADVECTION PATTERN AND A SECOND SATURDAY. && .AVIATION... VFR AREAS MVFR CIGS EARLY THIS AFTERNOON. CONDITIONS DETERIORATING WITH WIDESPREAD IFR CONDITIONS IN -SN BR LATE THIS AFTERNOON AND MUCH OF TONIGHT. CONDITIONS IMPROVING MONDAY MORNING WITH MAINLY VFR CONDITIONS BY AFTERNOONS. WINDS INCREASING A BIT LATER TODAY AND TONIGHT BUT GENERALLY AOB 15 KT. WIND GUSTS EXCEEDING 25 KNOTS IN SOME PLACES MONDAY WITH LOCAL BLOWING SNOW. && .HYDROLOGY... NO PROBLEMS ANTICIPATED. STREAMS AND RIVERS WILL CONTINUE TO DRAW DOWN. ANY PRECIPITATION WILL BE IN THE FORM OF SNOW THROUGH TUESDAY. ICE WILL CONTINUE TO FORM ON STREAMS AND LAKES. && $$ SHORT TERM (UPDATE)...WASULA AVIATION (UPDATE)...WASULA ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE RALEIGH NC 815 PM EST SUN DEC 26 2004 .SHORT TERM (REST OF TONIGHT)... CLEAR SKIES ACROSS THE CWA EXCEPT FEW PATCHES OF STRATOCU SKIRTING ACROSS NORTHERN TIER. MAY SEE FEW PATCHES CONTINUE MOVING ACROSS REST OF THE NIGHT. EVENING SOUNDINGS SHOW SOME MOISTURE AROUND 850MB...ALSO INDICATED ON RUC/M-ETA. WINDS AT MOST LOCATIONS HAVE DIMINISHED TO NEARLY CALM EXCEPT NORTHEAST SECTIONS. MAY NEED TO MAKE MINOR ADJUSTMENTS TO TEMPERATURES...ESPECIALLY IN SNOW COVERED AREAS. SO LATE EVENING UPDATE TO REMOVE REFERENCE TO EVENING. KEEP MOSTLY CLEAR SKIES BUT WILL INCREASE SKY COVER IN GRIDS. WILL LOWER MINS A FEW DEGREES. && .RAH WATCHES/WARNINGS/ADVISORIES... NC...NONE. && $$ SHORT TERM...RA nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 830 PM CST SUN DEC 26 2004 FORECAST CHALLENGE CONCERNS TEMPERATURES AND SNOW CHANCES. WEAK RETURNS FROM KMVX-88D CONTINUE TO SHIFT EAST ACROSS E ND INTO NW MN HOWEVER APPEARS TO MAINLY MID CLOUD. KMBX RETURNS A LITTLE STRONGER HOWEVER METARS NOT VERY IMPRESSIVE FOR SNOW INDICATIONS. LOWEST CONDENSTATION PRESSURE DEFICITS CURRENTLY OVER S CANADA FROM RUC TO SAG SOUTH SOMEWHAT OVERNIGHT AHEAD OF COLD FRONT. FOR THIS WILL MAINTAIN MID RANGE POPS ACROSS NORTH WITH LESSER AMOUNTS ACROSS SOUTH HALF. TEMPERATURES WITH SOUTHERLY FLOW...CLOUDS AND WARM ADVECTION HAVE BEEN STEADY/RISING THIS EVENING. LOW LEVEL COLD ADVECTION ONLY REACHES NW AND FAR N BY 12Z. MAY NEED TO BUMP UP TEMPERATURES SOMEWHAT OVER REMAINDER OF FA TO REFLECT STEADY/RISING TEMPERATURES. .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ VOELKER nd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE WILMINGTON OH 117 PM EST SUN DEC 26 2004 .AVIATION... SOME PATCHY IFR STRAUS REMAINS ALONG THE I-70 CORRIDOR...BUT EXPECT THIS TO MIX OUT THIS AFTERNOON. WILL SEE SOME STRATO-CU IN THE 4000 TO 6000 FOOT RANGE LINGER A LITTLE LONGER...BUT WILL FORECAST CLEARING AT ALL THE TAF SITES BY 06Z. DEPENDING HOW EARLY WE CLEAR...COULD SEE FOG DEVELOP LATE. HAVE INTROUDCED MVFR FOG LATE AT ALL SITES...WITH A TEMPO IFR AT DAY. && .SHORT TERM (REST OF TODAY)... && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 934 AM EST SUN DEC 26 2004 SHORT TERM (REST OF TODAY)... CLIPPER SYSTEM MOVING EAST OF THE FORECAST AREA THIS MORNING ALLOWING LIGHT SNOW TO END. WILL UPDATE TO REMOVE SNOW CHANCES... BUT LIKELY LEAVE FLURRY MENTION OVER THE NORTHERN ZONES WITH CYCLONIC LOW LEVEL FLOW ACROSS THE LAKES AND 850 TEMPS DROPPING BELOW MINUS 12 C. MODERATE COLD ADVECTION IS ENSUING BEHIND THE CLIPPER. THE LATEST GUIDANCE INDICATES A 3 TO 5 DEGREE DROP AT 850 MB TODAY...AND WITH THE NORTHWEST SURFACE FLOW OVER AN EXTENSIVE SNOWPACK I THINK TEMPERATURES WILL ONLY REBOUND SLIGHTLY. GRIDS HAVE ALREADY BEEN UPDATED TO REFLECT THIS...UPDATED TEXT PRODUCTS WILL BE AVAILABLE IN A FEW MINUTES. JOHNSTONE THE FOLLOWING WAS ORIGINALLY ISSUED AT 703 AM EST SUN DEC 26 2004 SHORT TERM (TODAY) UPDATED SOUTHERN ZONES TO ACCOUNT FOR AREA OF SNOW MOVING THROUGH THIS MORNING ASSOCIATED WITH CLIPPER SYSTEM. INCREASED POPS AND MENTIONED SOME ACCUMULATIONS LESS THAN AN INCH. PREVIOUS DISCUSSIONS... THE FOLLOWING WAS ORIGINALLY ISSUED AT 610 AM EST SUN DEC 26 2004 AVIATION (12Z-12Z)... CIGS HAVE LOWERED THROUGHOUT THE NIGHT. OCCASIONAL MVFR CIG AND VSBY IN SCT AREAS OF SNOW THIS MORNING. LATEST RUC MODEL SEEMS TO HAVE A GOOD HANDLE ON SHORT WAVE MOVING THROUGH OHIO VALLEY THIS MORNING. SNOW SHOULD TAPER OFF IN THE 15Z TO 16Z TIME FRAME AT TAF SITES. WILL FORECAST CIGS TO LOWER TO BETWEEN 2000 AND 3000 FEET FOR MOST OF DAY. CIG EXPECTED TO BECOME UNRESTRICTED AT MOST TAF SITES AFT 02Z. THE FOLLOWING WAS ORIGINALLY ISSUED AT 330 AM EST SUN DEC 26 2004 SHORT TERM (TODAY THROUGH TUESDAY NIGHT)... CLIPPER SYSTEM INITIALLY THOUGHT TO BE OVER IN WESTERN FA BY DAYBREAK...BUT ACCUM NEAR AN INCH BACK IN INDIANA...AND SOME LOCAL REPORTS OF LIGHT ACCUMULATION WILL PROMPT A LIKELY WORDING THIS MORNING IN NORTHERN HALF...WTH MENTION OF UP TO AN INCH ACCUM. FOR LATER TODAY WTH PASSAGE OF CLIPPER...TMPS SIMILAR TO SAT HIGHS...THEN PARTIAL CLEARING BEGINS TOWARD SUNSET. WTH FRESH DUSTING OF SNOW AND HIGH SETTLING INTO FA...TMPS OVER SNOWPACK SHOULD BE NEAR ZERO ONCE AGAIN. AS PER IND DISCUSSION...STRONG INVERSION MAY RESULT IN SOME STRATUS OR FOG WHICH MAY HAMPER THE BEST RADIATIONAL COOLING. FOR MONDAY...STRONGER WAA SETS UP AS HIGH PUSHES OFF TO EAST. AFTER FIRST PERIOD...HAVE GENERALLY GONE CLOSER TO ETA NUMBERS WITH SOME MODIFICATIONS. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. IN...NONE. KY...NONE. && $$ oh AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE WILMINGTON OH 934 AM EST SUN DEC 26 2004 .SHORT TERM (REST OF TODAY)... CLIPPER SYSTEM MOVING EAST OF THE FORECAST AREA THIS MORNING ALLOWING LIGHT SNOW TO END. WILL UPDATE TO REMOVE SNOW CHANCES... BUT LIKELY LEAVE FLURRY MENTION OVER THE NORTHERN ZONES WITH CYCLONIC LOW LEVEL FLOW ACROSS THE LAKES AND 850 TEMPS DROPPING BELOW MINUS 12 C. MODERATE COLD ADVECTION IS ENSUING BEHIND THE CLIPPER. THE LATEST GUIDANCE INDICATES A 3 TO 5 DEGREE DROP AT 850 MB TODAY...AND WITH THE NORTHWEST SURFACE FLOW OVER AN EXTENSIVE SNOWPACK I THINK TEMPERATURES WILL ONLY REBOUND SLIGHTLY. GRIDS HAVE ALREADY BEEN UPDATED TO REFLECT THIS...UPDATED TEXT PRODUCTS WILL BE AVAILABLE IN A FEW MINUTES. JOHNSTONE && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 703 AM EST SUN DEC 26 2004 SHORT TERM (TODAY) UPDATED SOUTHERN ZONES TO ACCOUNT FOR AREA OF SNOW MOVING THROUGH THIS MORNING ASSOCIATED WITH CLIPPER SYSTEM. INCREASED POPS AND MENTIONED SOME ACCUMULATIONS LESS THAN AN INCH. PREVIOUS DISCUSSIONS... THE FOLLOWING WAS ORIGINALLY ISSUED AT 610 AM EST SUN DEC 26 2004 AVIATION (12Z-12Z)... CIGS HAVE LOWERED THROUGHOUT THE NIGHT. OCCASIONAL MVFR CIG AND VSBY IN SCT AREAS OF SNOW THIS MORNING. LATEST RUC MODEL SEEMS TO HAVE A GOOD HANDLE ON SHORT WAVE MOVING THROUGH OHIO VALLEY THIS MORNING. SNOW SHOULD TAPER OFF IN THE 15Z TO 16Z TIME FRAME AT TAF SITES. WILL FORECAST CIGS TO LOWER TO BETWEEN 2000 AND 3000 FEET FOR MOST OF DAY. CIG EXPECTED TO BECOME UNRESTRICTED AT MOST TAF SITES AFT 02Z. THE FOLLOWING WAS ORIGINALLY ISSUED AT 330 AM EST SUN DEC 26 2004 SHORT TERM (TODAY THROUGH TUESDAY NIGHT)... CLIPPER SYSTEM INITIALLY THOUGHT TO BE OVER IN WESTERN FA BY DAYBREAK...BUT ACCUM NEAR AN INCH BACK IN INDIANA...AND SOME LOCAL REPORTS OF LIGHT ACCUMULATION WILL PROMPT A LIKELY WORDING THIS MORNING IN NORTHERN HALF...WTH MENTION OF UP TO AN INCH ACCUM. FOR LATER TODAY WTH PASSAGE OF CLIPPER...TMPS SIMILAR TO SAT HIGHS...THEN PARTIAL CLEARING BEGINS TOWARD SUNSET. WTH FRESH DUSTING OF SNOW AND HIGH SETTLING INTO FA...TMPS OVER SNOWPACK SHOULD BE NEAR ZERO ONCE AGAIN. AS PER IND DISCUSSION...STRONG INVERSION MAY RESULT IN SOME STRATUS OR FOG WHICH MAY HAMPER THE BEST RADIATIONAL COOLING. FOR MONDAY...STRONGER WAA SETS UP AS HIGH PUSHES OFF TO EAST. AFTER FIRST PERIOD...HAVE GENERALLY GONE CLOSER TO ETA NUMBERS WITH SOME MODIFICATIONS. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. IN...NONE. KY...NONE. && $$ oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 703 AM EST SUN DEC 26 2004 .SHORT TERM (TODAY) UPDATED SOUTHERN ZONES TO ACCOUNT FOR AREA OF SNOW MOVING THROUGH THIS MORNING ASSOCIATED WITH CLIPPER SYSTEM. INCREASED POPS AND MENTIONED SOME ACCUMULATIONS LESS THAN AN INCH. && .PREVIOUS DISCUSSIONS... THE FOLLOWING WAS ORIGINALLY ISSUED AT 610 AM EST SUN DEC 26 2004 AVIATION (12Z-12Z)... CIGS HAVE LOWERED THROUGHOUT THE NIGHT. OCCASIONAL MVFR CIG AND VSBY IN SCT AREAS OF SNOW THIS MORNING. LATEST RUC MODEL SEEMS TO HAVE A GOOD HANDLE ON SHORT WAVE MOVING THROUGH OHIO VALLEY THIS MORNING. SNOW SHOULD TAPER OFF IN THE 15Z TO 16Z TIME FRAME AT TAF SITES. WILL FORECAST CIGS TO LOWER TO BETWEEN 2000 AND 3000 FEET FOR MOST OF DAY. CIG EXPECTED TO BECOME UNRESTRICTED AT MOST TAF SITES AFT 02Z. THE FOLLOWING WAS ORIGINALLY ISSUED AT 330 AM EST SUN DEC 26 2004 SHORT TERM (TODAY THROUGH TUESDAY NIGHT)... CLIPPER SYSTEM INITIALLY THOUGHT TO BE OVER IN WESTERN FA BY DAYBREAK...BUT ACCUM NEAR AN INCH BACK IN INDIANA...AND SOME LOCAL REPORTS OF LIGHT ACCUMULATION WILL PROMPT A LIKELY WORDING THIS MORNING IN NORTHERN HALF...WTH MENTION OF UP TO AN INCH ACCUM. FOR LATER TODAY WTH PASSAGE OF CLIPPER...TMPS SIMILAR TO SAT HIGHS...THEN PARTIAL CLEARING BEGINS TOWARD SUNSET. WTH FRESH DUSTING OF SNOW AND HIGH SETTLING INTO FA...TMPS OVER SNOWPACK SHOULD BE NEAR ZERO ONCE AGAIN. AS PER IND DISCUSSION...STRONG INVERSION MAY RESULT IN SOME STRATUS OR FOG WHICH MAY HAMPER THE BEST RADIATIONAL COOLING. FOR MONDAY...STRONGER WAA SETS UP AS HIGH PUSHES OFF TO EAST. AFTER FIRST PERIOD...HAVE GENERALLY GONE CLOSER TO ETA NUMBERS WITH SOME MODIFICATIONS. .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. IN...NONE. KY...NONE. && $$ oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 610 AM EST SUN DEC 26 2004 .AVIATION (12Z-12Z)... CIGS HAVE LOWERED THROUGHOUT THE NIGHT. OCCASIONAL MVFR CIG AND VSBY IN SCT AREAS OF SNOW THIS MORNING. LATEST RUC MODEL SEEMS TO HAVE A GOOD HANDLE ON SHORT WAVE MOVING THROUGH OHIO VALLEY THIS MORNING. SNOW SHOULD TAPER OFF IN THE 15Z TO 16Z TIME FRAME AT TAF SITES. WILL FORECAST CIGS TO LOWER TO BETWEEN 2000 AND 3000 FEET FOR MOST OF DAY. CIG EXPECTED TO BECOME UNRESTRICTED AT MOST TAF SITES AFT 02Z. && .PREVIOUS DISCUSSIONS... THE FOLLOWING WAS ORIGINALLY ISSUED AT 330 AM EST SUN DEC 26 2004 SHORT TERM (TODAY THROUGH TUESDAY NIGHT)... CLIPPER SYSTEM INITIALLY THOUGHT TO BE OVER IN WESTERN FA BY DAYBREAK...BUT ACCUM NEAR AN INCH BACK IN INDIANA...AND SOME LOCAL REPORTS OF LIGHT ACCUMULATION WILL PROMPT A LIKELY WORDING THIS MORNING IN NORTHERN HALF...WTH MENTION OF UP TO AN INCH ACCUM. FOR LATER TODAY WTH PASSAGE OF CLIPPER...TMPS SIMILAR TO SAT HIGHS...THEN PARTIAL CLEARING BEGINS TOWARD SUNSET. WTH FRESH DUSTING OF SNOW AND HIGH SETTLING INTO FA...TMPS OVER SNOWPACK SHOULD BE NEAR ZERO ONCE AGAIN. AS PER IND DISCUSSION...STRONG INVERSION MAY RESULT IN SOME STRATUS OR FOG WHICH MAY HAMPER THE BEST RADIATIONAL COOLING. FOR MONDAY...STRONGER WAA SETS UP AS HIGH PUSHES OFF TO EAST. AFTER FIRST PERIOD...HAVE GENERALLY GONE CLOSER TO ETA NUMBERS WITH SOME MODIFICATIONS. THE FOLLOWING WAS ORIGINALLY ISSUED AT 938 PM EST SAT DEC 25 2004 SHORT TERM (TONIGHT AND SUNDAY MORNING)... OBSERVATIONS AND RADAR SHOWING SNOW ASSOCIATED WITH A CLIPPER PROGRESSING FASTER THAN EARLIER THOUGHT. THIS GOES ALONG MORE WITH THE QUICKER 18Z GFS SOLUTION. GIVEN THIS TREND HAVE UPDATED TO BRING SNOW THROUGH THE FORECAST AREA FASTER. KEPT POPS THE SAME. TEMPERATURES HAVE BEEN STEADY OR SLOWLY RISING. WITH CLOUD COVER AND LIGHT SOUTHERLY WINDS FEEL THAT THEY WILL NOT BE ABLE TO FALL TOO MUCH LATER TONIGHT SO RAISED MINIMUMS QUITE A BIT. .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. IN...NONE. KY...NONE. && $$ oh AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 115 PM EST SUN DEC 26 2004 .SHORT TERM (REST OF TODAY)... A QUICK UPDATE DUE TO HIGHER THAN EXPECTED TEMPERATURES OVER THE WEST...ESPECIALLY IN THE MOUNTAINS. FULL SUN CONTINUES TO SPREAD FROM WEST TO EAST. MADE SLIGHT ADJUSTMENTS TO SKY AND LEFT ALL ELSE. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 1012 AM EST SUN DEC 26 2004 SHORT TERM (REST OF TODAY THROUGH TONIGHT)... UPDATED TO ADD LAKE WIND ADVISORY IN THE NRN NC MTNS AS WINDS SHOULD COME UP TO 15 TO 25 LATE TODAY IN THE NORTHWEST FLOW...AND PERSIST WITH WINDY CONDITIONS THROUGH TONIGHT. THE FOLLOWING WAS ORIGINALLY ISSUED AT 957 AM EST SUN DEC 26 2004 SHORT TERM (REST OF TODAY)... PLAN ON CANCELLING THE WINTER WEATHER ADVISORY SHORTLY WITH PRECIPITATION BAND SAFELY EAST OF THE AREA AND ONLY ONE REPORT OF SOME MINOR ACCUMS IN SOUTHEAST CHESTER COUNTY. COLD IR CLOUD SHIELD IS WARMING AND SHRINKING RAPIDLY AND MUCH OF THE WRN PORTION OF THE FORECAST AREA COULD SEE CONSIDERABLE INSOLATION THROUGH THE AFTERNOON. HOWEVER...FAIRLY SOLID HIGH STRATOCU OR LOW AC DECK ADVANCING EASTWARD THROUGH ERN TN WILL BRING ADDITIONAL CLOUDS BACK AT LEAST INTO THE HIGHER TERRAIN AND POSSIBLY THE NRN TIER. WILL THUS PUSH TEMPS UP 3 TO 5 DEGREES IN SW NON MTN LOCATIONS...A COUPLE OF DEGREES IN THE MTNS...AND AROUND A DEGREE IN THE NE PARTS. THE FOLLOWING WAS ORIGINALLY ISSUED AT 608 AM EST SUN DEC 26 2004 SHORT TERM (REST OF TODAY)... WL CANCEL THE WINTER WEATHER ADVISORY FOR ALL COUNTIES EXCEPT FOR UNION CO NC AND CHESTER CO. DEFORMATION ZONE HAS SET UP ABOUT 20 MILES FARTHER E THAN ORIGINALLY EXPECTED. THIS SHOULD SPARE MOST OF THE CWFA ACCUMULATING SLEET AND SNOW. HOWEVER...PARTS OF CHESTER AND UNION CO NC WL STILL PROBABLY SEE A FEW HRS OF A MODERATE SNOW/SLEET MIX. RUC AND ETA SOUNDINGS STILL IMPLY THAT MOST OF THE PCPN IN OUR AREA SHOULD BE SNOW AND AREAS FROM GREAT FALLS TO STURDIVANTS MAY STILL GET AN INCH OR TWO. THE FOLLOWING WAS ORIGINALLY ISSUED AT 253 AM EST SUN DEC 26 2004 SHORT TERM (TODAY THROUGH WEDNESDAY)... THE 300K SFC ON THE ETA AND GFS DOES A GOOD JOB OF SHOWING THE SHARP DEFORMATION ZONE THAT WL CONTINUE TO WORK ACROSS THE MIDLANDS AND SRN UPSTATE THIS MORNING. AT 0600 UTC THE ETA SHOWED DOWNGLIDE OVER JUST ABOUT THE ENTIRE GSP CWFA...WHICH BECOME STRONG UPGLIDE JUST INTO CAE/S AREA. THIS MATCHES UP WELL W/RADAR TRENDS AND SFC REPORTS. BY 0900 UTC THE THIS AREA OF ASCENT JUST WORKS INTO SRN UNION... CHESTER AND GREENWOOD COUNTIES...THEN PUSHES E A LITTLE AFTER 1200 UTC. ALOFT THE DEFORMATION ZONE SLOPES BACK TO THE WEST...AND THERE IS GOOD OMEGA BETWEEN ABOUT 500-300 MB OVER A SIZABLE PART OF THE UPSTATE AND SRN NC PIEDMONT...BUT THERE SHOULD BE LIMITED PCPN W OF THE 700 MB DEFORMATION ZONE. IR SATELLITE IMAGERY ALSO SUPPORTS THIS IDEA. TAKING THE MID POINT (ORIENTED PERPENDICULAR TO THE 1000-500 MB THICKNESSES) OF THE LEAF OF COOLING CLOUD TOPS AHEAD OF THE EJECTING 500 MB LOW...THE AREA OF HEAVIEST PCPN WL JUST SKIRT THE SRN TIER OUR OUR ZONES. FINALLY...THE BEST FRONTOGENETICAL FORCING AT H7 ON THE ETA AND GFS SETS UP JUST E. USING THE SNOWBAND AWIPS PROCEDURE...BEST AREA OF SLOPING FRONTOGENESIS AND SATURATED EPV LOOKS TO STAY E OF THE CWFA. ATTM REFLECTIVITIES ARE INCREASING RIGHT IN THIS AREA OF FRONTOGENESIS ACROSS THE HEART OF MIDLANDS. MODEL SOUNDINGS GENERALLY SUPPORT ALL SNOW THIS FAR NE...SO WL GO WITH THAT IN THE GRIDS AND REMOVE THE MIXED PCPN. AS FOR HOW MUCH...THE SRN MOST PART OF THE GREENWOOD TO UNION NC ZONES MIGHT APPROACH WINTER STORM CRITERIA BY MID-MORNING. HOWEVER...COUNTYWIDE AVERAGES SHOULD FALL BELOW WINTER STORM CRITERIA. THIS MATCHES UP QUITE WELL WITH THE CURRENT ADVISORY...AND DO NOT PLAN TO UPGRADE ANY COUNTIES TO A WARNING YET. SO OVERALL THERE IS REASONABLE CONFIDENCE IN THE TRACK OF THE HEAVY PCPN AND PCPN TYPE THE NEXT 6 TO 9 HRS. HOWEVER...A TRACK ERROR OF EVEN 10 MILES WOULD MAKE A BIG DIFFERENCE IN PCPN TOTALS. ATTM IT APPEARS THAT THE I-85 URBAN CORRIDOR FROM CLT TO GSP SHOULD STAY WEST OF THE HEAVY SNOW. THE WEATHER WL BE QUIET FOR SEVERAL DAYS AFTER THIS MORNING/S EXCITEMENT AS A NRN STREAM SHORT WAVE WL PUSH ALL THIS MESS OUT TO SEA BY THIS AFTN. LOWERED DWPTS QUITE A BIT MON AND TUE AND CUT SKY COVER IN HOPES OF GETTING SUNNY WORDING INTO THE GRIDS ON MON. STAYED QUITE CLOSE TO THE MAV NUMBERS THROUGH THE MIDDLE OF THE WEEK. LONG TERM (WEDNESDAY NIGHT THROUGH SATURDAY)... NO CHANGES BEYOND WED. AVIATION... MOISTURE WILL CONTINUE SPREADING INTO THE REGION FROM THE SOUTH EARLY THIS MORNING WITH DEEPER MOISTURE STILL EXPECTED TO REMAIN SOUTHEAST OF THE TAF SITES. WEATHER AT TAF SITES WILL BE HIGHLY DEPENDENT ON SFC LOW TRACK. CURRENT FORECAST TRACK WILL KEEP ANY SNOW OR SLEET THREAT MAINLY SOUTH OF A LINE FROM ABBEVILLE TO LAURENS TO MONROE DURING THROUGH 15Z. WILL KEEP BROKEN AC DECK EARLY THIS MORNING...WITH INCREASING NRLY FLOW. CLOUDS WILL DECREASE FROM W TO E THROUGH THE MORNING HOURS. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...LAKE WIND ADVISORY FOR ZONES NCZ033-049-050 TODAY AND TONIGHT. SC...NONE. && $$ SHORT TERM (UPDATE)...DEO/HG LONG TERM...SAB sc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1012 AM EST SUN DEC 26 2004 .SHORT TERM (REST OF TODAY THROUGH TONIGHT)... UPDATED TO ADD LAKE WIND ADVISORY IN THE NRN NC MTNS AS WINDS SHOULD COME UP TO 15 TO 25 LATE TODAY IN THE NORTHWEST FLOW...AND PERSIST WITH WINDY CONDITIONS THROUGH TONIGHT. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 957 AM EST SUN DEC 26 2004 SHORT TERM (REST OF TODAY)... PLAN ON CANCELLING THE WINTER WEATHER ADVISORY SHORTLY WITH PRECIPITATION BAND SAFELY EAST OF THE AREA AND ONLY ONE REPORT OF SOME MINOR ACCUMS IN SOUTHEAST CHESTER COUNTY. COLD IR CLOUD SHIELD IS WARMING AND SHRINKING RAPIDLY AND MUCH OF THE WRN PORTION OF THE FORECAST AREA COULD SEE CONSIDERABLE INSOLATION THROUGH THE AFTERNOON. HOWEVER...FAIRLY SOLID HIGH STRATOCU OR LOW AC DECK ADVANCING EASTWARD THROUGH ERN TN WILL BRING ADDITIONAL CLOUDS BACK AT LEAST INTO THE HIGHER TERRAIN AND POSSIBLY THE NRN TIER. WILL THUS PUSH TEMPS UP 3 TO 5 DEGREES IN SW NON MTN LOCATIONS...A COUPLE OF DEGREES IN THE MTNS...AND AROUND A DEGREE IN THE NE PARTS. THE FOLLOWING WAS ORIGINALLY ISSUED AT 608 AM EST SUN DEC 26 2004 SHORT TERM (REST OF TODAY)... WL CANCEL THE WINTER WEATHER ADVISORY FOR ALL COUNTIES EXCEPT FOR UNION CO NC AND CHESTER CO. DEFORMATION ZONE HAS SET UP ABOUT 20 MILES FARTHER E THAN ORIGINALLY EXPECTED. THIS SHOULD SPARE MOST OF THE CWFA ACCUMULATING SLEET AND SNOW. HOWEVER...PARTS OF CHESTER AND UNION CO NC WL STILL PROBABLY SEE A FEW HRS OF A MODERATE SNOW/SLEET MIX. RUC AND ETA SOUNDINGS STILL IMPLY THAT MOST OF THE PCPN IN OUR AREA SHOULD BE SNOW AND AREAS FROM GREAT FALLS TO STURDIVANTS MAY STILL GET AN INCH OR TWO. THE FOLLOWING WAS ORIGINALLY ISSUED AT 253 AM EST SUN DEC 26 2004 SHORT TERM (TODAY THROUGH WEDNESDAY)... THE 300K SFC ON THE ETA AND GFS DOES A GOOD JOB OF SHOWING THE SHARP DEFORMATION ZONE THAT WL CONTINUE TO WORK ACROSS THE MIDLANDS AND SRN UPSTATE THIS MORNING. AT 0600 UTC THE ETA SHOWED DOWNGLIDE OVER JUST ABOUT THE ENTIRE GSP CWFA...WHICH BECOME STRONG UPGLIDE JUST INTO CAE/S AREA. THIS MATCHES UP WELL W/RADAR TRENDS AND SFC REPORTS. BY 0900 UTC THE THIS AREA OF ASCENT JUST WORKS INTO SRN UNION... CHESTER AND GREENWOOD COUNTIES...THEN PUSHES E A LITTLE AFTER 1200 UTC. ALOFT THE DEFORMATION ZONE SLOPES BACK TO THE WEST...AND THERE IS GOOD OMEGA BETWEEN ABOUT 500-300 MB OVER A SIZABLE PART OF THE UPSTATE AND SRN NC PIEDMONT...BUT THERE SHOULD BE LIMITED PCPN W OF THE 700 MB DEFORMATION ZONE. IR SATELLITE IMAGERY ALSO SUPPORTS THIS IDEA. TAKING THE MID POINT (ORIENTED PERPENDICULAR TO THE 1000-500 MB THICKNESSES) OF THE LEAF OF COOLING CLOUD TOPS AHEAD OF THE EJECTING 500 MB LOW...THE AREA OF HEAVIEST PCPN WL JUST SKIRT THE SRN TIER OUR OUR ZONES. FINALLY...THE BEST FRONTOGENETICAL FORCING AT H7 ON THE ETA AND GFS SETS UP JUST E. USING THE SNOWBAND AWIPS PROCEDURE...BEST AREA OF SLOPING FRONTOGENESIS AND SATURATED EPV LOOKS TO STAY E OF THE CWFA. ATTM REFLECTIVITIES ARE INCREASING RIGHT IN THIS AREA OF FRONTOGENESIS ACROSS THE HEART OF MIDLANDS. MODEL SOUNDINGS GENERALLY SUPPORT ALL SNOW THIS FAR NE...SO WL GO WITH THAT IN THE GRIDS AND REMOVE THE MIXED PCPN. AS FOR HOW MUCH...THE SRN MOST PART OF THE GREENWOOD TO UNION NC ZONES MIGHT APPROACH WINTER STORM CRITERIA BY MID-MORNING. HOWEVER...COUNTYWIDE AVERAGES SHOULD FALL BELOW WINTER STORM CRITERIA. THIS MATCHES UP QUITE WELL WITH THE CURRENT ADVISORY...AND DO NOT PLAN TO UPGRADE ANY COUNTIES TO A WARNING YET. SO OVERALL THERE IS REASONABLE CONFIDENCE IN THE TRACK OF THE HEAVY PCPN AND PCPN TYPE THE NEXT 6 TO 9 HRS. HOWEVER...A TRACK ERROR OF EVEN 10 MILES WOULD MAKE A BIG DIFFERENCE IN PCPN TOTALS. ATTM IT APPEARS THAT THE I-85 URBAN CORRIDOR FROM CLT TO GSP SHOULD STAY WEST OF THE HEAVY SNOW. THE WEATHER WL BE QUIET FOR SEVERAL DAYS AFTER THIS MORNING/S EXCITEMENT AS A NRN STREAM SHORT WAVE WL PUSH ALL THIS MESS OUT TO SEA BY THIS AFTN. LOWERED DWPTS QUITE A BIT MON AND TUE AND CUT SKY COVER IN HOPES OF GETTING SUNNY WORDING INTO THE GRIDS ON MON. STAYED QUITE CLOSE TO THE MAV NUMBERS THROUGH THE MIDDLE OF THE WEEK. LONG TERM (WEDNESDAY NIGHT THROUGH SATURDAY)... NO CHANGES BEYOND WED. AVIATION... MOISTURE WILL CONTINUE SPREADING INTO THE REGION FROM THE SOUTH EARLY THIS MORNING WITH DEEPER MOISTURE STILL EXPECTED TO REMAIN SOUTHEAST OF THE TAF SITES. WEATHER AT TAF SITES WILL BE HIGHLY DEPENDENT ON SFC LOW TRACK. CURRENT FORECAST TRACK WILL KEEP ANY SNOW OR SLEET THREAT MAINLY SOUTH OF A LINE FROM ABBEVILLE TO LAURENS TO MONROE DURING THROUGH 15Z. WILL KEEP BROKEN AC DECK EARLY THIS MORNING...WITH INCREASING NRLY FLOW. CLOUDS WILL DECREASE FROM W TO E THROUGH THE MORNING HOURS. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...LAKE WIND ADVISORY FOR ZONES NCZ033-049-050 THROUGH TONIGHT. SC...NONE. && $$ SHORT TERM (UPDATE)...HG sc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 957 AM EST SUN DEC 26 2004 .SHORT TERM (REST OF TODAY)... PLAN ON CANCELLING THE WINTER WEATHER ADVISORY SHORTLY WITH PRECIPITATION BAND SAFELY EAST OF THE AREA AND ONLY ONE REPORT OF SOME MINOR ACCUMS IN SOUTHEAST CHESTER COUNTY. COLD IR CLOUD SHIELD IS WARMING AND SHRINKING RAPIDLY AND MUCH OF THE WRN PORTION OF THE FORECAST AREA COULD SEE CONSIDERABLE INSOLATION THROUGH THE AFTERNOON. HOWEVER...FAIRLY SOLID HIGH STRATOCU OR LOW AC DECK ADVANCING EASTWARD THROUGH ERN TN WILL BRING ADDITIONAL CLOUDS BACK AT LEAST INTO THE HIGHER TERRAIN AND POSSIBLY THE NRN TIER. WILL THUS PUSH TEMPS UP 3 TO 5 DEGREES IN SW NON MTN LOCATIONS...A COUPLE OF DEGREES IN THE MTNS...AND AROUND A DEGREE IN THE NE PARTS. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 608 AM EST SUN DEC 26 2004 SHORT TERM (REST OF TODAY)... WL CANCEL THE WINTER WEATHER ADVISORY FOR ALL COUNTIES EXCEPT FOR UNION CO NC AND CHESTER CO. DEFORMATION ZONE HAS SET UP ABOUT 20 MILES FARTHER E THAN ORIGINALLY EXPECTED. THIS SHOULD SPARE MOST OF THE CWFA ACCUMULATING SLEET AND SNOW. HOWEVER...PARTS OF CHESTER AND UNION CO NC WL STILL PROBABLY SEE A FEW HRS OF A MODERATE SNOW/SLEET MIX. RUC AND ETA SOUNDINGS STILL IMPLY THAT MOST OF THE PCPN IN OUR AREA SHOULD BE SNOW AND AREAS FROM GREAT FALLS TO STURDIVANTS MAY STILL GET AN INCH OR TWO. THE FOLLOWING WAS ORIGINALLY ISSUED AT 253 AM EST SUN DEC 26 2004 SHORT TERM (TODAY THROUGH WEDNESDAY)... THE 300K SFC ON THE ETA AND GFS DOES A GOOD JOB OF SHOWING THE SHARP DEFORMATION ZONE THAT WL CONTINUE TO WORK ACROSS THE MIDLANDS AND SRN UPSTATE THIS MORNING. AT 0600 UTC THE ETA SHOWED DOWNGLIDE OVER JUST ABOUT THE ENTIRE GSP CWFA...WHICH BECOME STRONG UPGLIDE JUST INTO CAE/S AREA. THIS MATCHES UP WELL W/RADAR TRENDS AND SFC REPORTS. BY 0900 UTC THE THIS AREA OF ASCENT JUST WORKS INTO SRN UNION... CHESTER AND GREENWOOD COUNTIES...THEN PUSHES E A LITTLE AFTER 1200 UTC. ALOFT THE DEFORMATION ZONE SLOPES BACK TO THE WEST...AND THERE IS GOOD OMEGA BETWEEN ABOUT 500-300 MB OVER A SIZABLE PART OF THE UPSTATE AND SRN NC PIEDMONT...BUT THERE SHOULD BE LIMITED PCPN W OF THE 700 MB DEFORMATION ZONE. IR SATELLITE IMAGERY ALSO SUPPORTS THIS IDEA. TAKING THE MID POINT (ORIENTED PERPENDICULAR TO THE 1000-500 MB THICKNESSES) OF THE LEAF OF COOLING CLOUD TOPS AHEAD OF THE EJECTING 500 MB LOW...THE AREA OF HEAVIEST PCPN WL JUST SKIRT THE SRN TIER OUR OUR ZONES. FINALLY...THE BEST FRONTOGENETICAL FORCING AT H7 ON THE ETA AND GFS SETS UP JUST E. USING THE SNOWBAND AWIPS PROCEDURE...BEST AREA OF SLOPING FRONTOGENESIS AND SATURATED EPV LOOKS TO STAY E OF THE CWFA. ATTM REFLECTIVITIES ARE INCREASING RIGHT IN THIS AREA OF FRONTOGENESIS ACROSS THE HEART OF MIDLANDS. MODEL SOUNDINGS GENERALLY SUPPORT ALL SNOW THIS FAR NE...SO WL GO WITH THAT IN THE GRIDS AND REMOVE THE MIXED PCPN. AS FOR HOW MUCH...THE SRN MOST PART OF THE GREENWOOD TO UNION NC ZONES MIGHT APPROACH WINTER STORM CRITERIA BY MID-MORNING. HOWEVER...COUNTYWIDE AVERAGES SHOULD FALL BELOW WINTER STORM CRITERIA. THIS MATCHES UP QUITE WELL WITH THE CURRENT ADVISORY...AND DO NOT PLAN TO UPGRADE ANY COUNTIES TO A WARNING YET. SO OVERALL THERE IS REASONABLE CONFIDENCE IN THE TRACK OF THE HEAVY PCPN AND PCPN TYPE THE NEXT 6 TO 9 HRS. HOWEVER...A TRACK ERROR OF EVEN 10 MILES WOULD MAKE A BIG DIFFERENCE IN PCPN TOTALS. ATTM IT APPEARS THAT THE I-85 URBAN CORRIDOR FROM CLT TO GSP SHOULD STAY WEST OF THE HEAVY SNOW. THE WEATHER WL BE QUIET FOR SEVERAL DAYS AFTER THIS MORNING/S EXCITEMENT AS A NRN STREAM SHORT WAVE WL PUSH ALL THIS MESS OUT TO SEA BY THIS AFTN. LOWERED DWPTS QUITE A BIT MON AND TUE AND CUT SKY COVER IN HOPES OF GETTING SUNNY WORDING INTO THE GRIDS ON MON. STAYED QUITE CLOSE TO THE MAV NUMBERS THROUGH THE MIDDLE OF THE WEEK. LONG TERM (WEDNESDAY NIGHT THROUGH SATURDAY)... NO CHANGES BEYOND WED. AVIATION... MOISTURE WILL CONTINUE SPREADING INTO THE REGION FROM THE SOUTH EARLY THIS MORNING WITH DEEPER MOISTURE STILL EXPECTED TO REMAIN SOUTHEAST OF THE TAF SITES. WEATHER AT TAF SITES WILL BE HIGHLY DEPENDENT ON SFC LOW TRACK. CURRENT FORECAST TRACK WILL KEEP ANY SNOW OR SLEET THREAT MAINLY SOUTH OF A LINE FROM ABBEVILLE TO LAURENS TO MONROE DURING THROUGH 15Z. WILL KEEP BROKEN AC DECK EARLY THIS MORNING...WITH INCREASING NRLY FLOW. CLOUDS WILL DECREASE FROM W TO E THROUGH THE MORNING HOURS. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SHORT TERM (UPDATE)...HG sc AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE COLUMBIA SC 730 AM EST SUN DEC 26 2004 .UPDATE... RADAR SHOWS PRECIPITATION ENDING FROM WEST TO EAST. MOSTLY FREEZING RAIN NOW. SNOW ACCUMULATIONS NO LONGER EXPECTED. FREEZING RAIN ACCUMULATIONS WILL TOTAL AROUND ONE QUARTER INCH ESPECIALLY ON ELEVATED SURFACES. EXPECT PRECIPITATION TO END NORTH AND WEST OF A LINE FROM AUGUSTA TO COLUMBIA TO LANCASTER BY 900 AM AND SOUTH AND EAST OF THAT LINE FROM 10 AM TO 11 AM. .SHORT TERM... AT 2 AM WE HAVE A MIXTURE OF PRECIPITATION TYPES FALLING ACROSS CENTRAL SC WITH TEMPERATURES RANGING BETWEEN 30 AND 34 DEGREES OVER THE AREA. THE MOST RECENT OBSRVATIONS AND REPORTS WE HAVE SHOW PREDOMINANTLY FREEZING RAIN WITH SOME SLEET MIXED IN. WE HAVE WIDESPREAD REPORTS OF ICING ON ROADWAYS...ESPECIALLY ON BRIDGES... OVERPASES AND ELEVATED SURFACES. THE GOING FORECAST HAS PREDOMINANTLY SNOW/SLEET FROM AUGUSTA TO COLUMBIA TO CHESTERFIELD NORTH AND WEST WITH FREEZING RAIN SOUTH AND EAST. THE LATEST OBSERVATIONS INDICATE THE FREEZING RAIN LINE MAY ACTUALLY BE FURTHER NORTH AND WEST SO WE ARE CURRENTLY LOOKING AT ADJUSTING THE PRECIPITATION TYPE WITH THE NEW FORECAST PACKAGE TO PREDOMINANTLY FREEZING RAIN WITH SOME SNOW MIXED IN. WE WOULD CORRESPONINGLY ADJUST SNOW ACCUMUATIONS DOWN AND FOCUS ON ICE ACCUMLATIONS. WE HAVE ALREADY HAD REPORTS OF 1/4 INCH ICE ACCUMULATIONS IN SOME AREAS. BOTH RUC AND ETA SHOW VERY TIGHT TEMPERATURE GRADIENT ALOFT WITH THE 0 DEG C LINE SPLITTING THE CWA. AT THE SURFACE...WET BULB TEMPS ARE BELOW 0 C OVER MOST OF THE AREA. && .LONG TERM... AFTER THIS SYSTEM MOVES OUT HIGH PRESSURE BUILDS OVER THE REGION BRINGING FAIR WEATHER THROUGH MOST OF THE WEEK. NO REAL CHANGE FROM THE PREVIOUS PACKAGE. && .AVIATION... CEILINGS AROUND 3-6 THOUSAND FEET WILL CONTINUE THROUGH 12Z AS MIXED BAG OF PRECIP WILL CONTINUE THROUGH THE PERIOD. RAIN IS BEING REPORTED SOUTH OF COLUMBIA AND INTO THE AGS AREA AND IS EXPECTED TO CONTINUE. OGB IS BELOW FREEZING AND HAS REPORTED RAIN. VISIBILITIES WILL STAY ABOVE 6 MILES ACROSS THE AREA...EXCEPT IN HEAVIER BANDS OF PRECIP. PRECIP WILL END AROUND 10 AM AND SKIES WILL BECOME MOSTLY SUNNY BY THIS AFTERNOON. WINDS WILL BE FROM THE NORTHEAST AT 10 TO 15 MPH AND WILL BECOME MORE NORTH LATER TODAY. && .PRELIMINARY POINT TEMPS/POPS... COLUMBIA 38 26 51 28 / 100 10 0 0 AUGUSTA 41 26 54 29 / 100 10 0 0 SUMTER 38 25 51 28 / 100 10 0 0 ORANGEBURG 39 25 53 29 / 100 10 0 0 && .CAE WATCHES/WARNINGS/ADVISORIES... SC...WINTER STORM WARNING TONIGHT AND SUNDAY MORNING SCZ009-014>016- 018-020>022-025>031-035>038-041. GA...WINTER STORM WARNING TONIGHT AND SUNDAY MORNING GAZ040-063>065- 077. && $$ 99/99 sc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 608 AM EST SUN DEC 26 2004 .SHORT TERM (REST OF TODAY)... WL CANCEL THE WINTER WEATHER ADVISORY FOR ALL COUNTIES EXCEPT FOR UNION CO NC AND CHESTER CO. DEFORMATION ZONE HAS SET UP ABOUT 20 MILES FARTHER E THAN ORIGINALLY EXPECTED. THIS SHOULD SPARE MOST OF THE CWFA ACCUMULATING SLEET AND SNOW. HOWEVER...PARTS OF CHESTER AND UNION CO NC WL STILL PROBABLY SEE A FEW HRS OF A MODERATE SNOW/SLEET MIX. RUC AND ETA SOUNDINGS STILL IMPLY THAT MOST OF THE PCPN IN OUR AREA SHOULD BE SNOW AND AREAS FROM GREAT FALLS TO STURDIVANTS MAY STILL GET AN INCH OR TWO. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 253 AM EST SUN DEC 26 2004 SHORT TERM (TODAY THROUGH WEDNESDAY)... THE 300K SFC ON THE ETA AND GFS DOES A GOOD JOB OF SHOWING THE SHARP DEFORMATION ZONE THAT WL CONTINUE TO WORK ACROSS THE MIDLANDS AND SRN UPSTATE THIS MORNING. AT 0600 UTC THE ETA SHOWED DOWNGLIDE OVER JUST ABOUT THE ENTIRE GSP CWFA...WHICH BECOME STRONG UPGLIDE JUST INTO CAE/S AREA. THIS MATCHES UP WELL W/RADAR TRENDS AND SFC REPORTS. BY 0900 UTC THE THIS AREA OF ASCENT JUST WORKS INTO SRN UNION... CHESTER AND GREENWOOD COUNTIES...THEN PUSHES E A LITTLE AFTER 1200 UTC. ALOFT THE DEFORMATION ZONE SLOPES BACK TO THE WEST...AND THERE IS GOOD OMEGA BETWEEN ABOUT 500-300 MB OVER A SIZABLE PART OF THE UPSTATE AND SRN NC PIEDMONT...BUT THERE SHOULD BE LIMITED PCPN W OF THE 700 MB DEFORMATION ZONE. IR SATELLITE IMAGERY ALSO SUPPORTS THIS IDEA. TAKING THE MID POINT (ORIENTED PERPENDICULAR TO THE 1000-500 MB THICKNESSES) OF THE LEAF OF COOLING CLOUD TOPS AHEAD OF THE EJECTING 500 MB LOW...THE AREA OF HEAVIEST PCPN WL JUST SKIRT THE SRN TIER OUR OUR ZONES. FINALLY...THE BEST FRONTOGENETICAL FORCING AT H7 ON THE ETA AND GFS SETS UP JUST E. USING THE SNOWBAND AWIPS PROCEDURE...BEST AREA OF SLOPING FRONTOGENESIS AND SATURATED EPV LOOKS TO STAY E OF THE CWFA. ATTM REFLECTIVITIES ARE INCREASING RIGHT IN THIS AREA OF FRONTOGENESIS ACROSS THE HEART OF MIDLANDS. MODEL SOUNDINGS GENERALLY SUPPORT ALL SNOW THIS FAR NE...SO WL GO WITH THAT IN THE GRIDS AND REMOVE THE MIXED PCPN. AS FOR HOW MUCH...THE SRN MOST PART OF THE GREENWOOD TO UNION NC ZONES MIGHT APPROACH WINTER STORM CRITERIA BY MID-MORNING. HOWEVER...COUNTYWIDE AVERAGES SHOULD FALL BELOW WINTER STORM CRITERIA. THIS MATCHES UP QUITE WELL WITH THE CURRENT ADVISORY...AND DO NOT PLAN TO UPGRADE ANY COUNTIES TO A WARNING YET. SO OVERALL THERE IS REASONABLE CONFIDENCE IN THE TRACK OF THE HEAVY PCPN AND PCPN TYPE THE NEXT 6 TO 9 HRS. HOWEVER...A TRACK ERROR OF EVEN 10 MILES WOULD MAKE A BIG DIFFERENCE IN PCPN TOTALS. ATTM IT APPEARS THAT THE I-85 URBAN CORRIDOR FROM CLT TO GSP SHOULD STAY WEST OF THE HEAVY SNOW. THE WEATHER WL BE QUIET FOR SEVERAL DAYS AFTER THIS MORNING/S EXCITEMENT AS A NRN STREAM SHORT WAVE WL PUSH ALL THIS MESS OUT TO SEA BY THIS AFTN. LOWERED DWPTS QUITE A BIT MON AND TUE AND CUT SKY COVER IN HOPES OF GETTING SUNNY WORDING INTO THE GRIDS ON MON. STAYED QUITE CLOSE TO THE MAV NUMBERS THROUGH THE MIDDLE OF THE WEEK. LONG TERM (WEDNESDAY NIGHT THROUGH SATURDAY)... NO CHANGES BEYOND WED. AVIATION... MOISTURE WILL CONTINUE SPREADING INTO THE REGION FROM THE SOUTH EARLY THIS MORNING WITH DEEPER MOISTURE STILL EXPECTED TO REMAIN SOUTHEAST OF THE TAF SITES. WEATHER AT TAF SITES WILL BE HIGHLY DEPENDENT ON SFC LOW TRACK. CURRENT FORECAST TRACK WILL KEEP ANY SNOW OR SLEET THREAT MAINLY SOUTH OF A LINE FROM ABBEVILLE TO LAURENS TO MONROE DURING THROUGH 15Z. WILL KEEP BROKEN AC DECK EARLY THIS MORNING...WITH INCREASING NRLY FLOW. CLOUDS WILL DECREASE FROM W TO E THROUGH THE MORNING HOURS. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...WINTER WEATHER ADVISORY FOR ZONE NCZ082 UNTIL 12 PM EST. SC...WINTER WEATHER ADVISORY FOR ZONE SCZ014 UNTIL 12 PM EST. && $$ SHORT TERM (UPDATE)...MCAVOY sc AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 825 PM MST SUN DEC 26 2004 .DISCUSSION...00Z KUNR SOUNDING SHOWS LARGE INVERSION TRAPPING MOISTURE WITH ACRTIC AIR PUSHED UP AGAINST THE BLACK HILLS. 00Z ETA/RUC STILL HAVEN/T CAUGHT ON TO LOW LEVEL MOISTURE. AREAS OF FOG SHOULD PERSIST OVER THE NORTHWEST HALF OF SD THROUGH TOMORROW MORNING. SHORTWAVE OVER SOUTHEAST MT WILL PUSH COLDER AIR INTO THE AREA OVERNIGHT...EVIDENCED BY SURFACE PRESSURE RISES BEHIND SURFACE BOUNDARY REFLECTION. THIS FRONT SHOULD FLUSH OUT SOME OF THE FOG AND PREVENT WIDESPREAD DENSE FOG. CALLS TO LAW ENFORCEMENT OFFICIALS INDICATE SPEARFISH...BELLE AND STURGIS HAVE SEEN FOG LIFT THIS EVENING. REST OF FORECAST IN DECENT SHAPE...WILL MAKE SOME MINOR TWEAKS WITH FORECAST UPDATE. && .AVIATION...MAIN CONCERN IS ARCTIC BOUNDARY STRETCHING FROM ERN MT THROUGH WRN SD. LIFR/IFR CONDS CONT ACRS THE PLAINS OF WRN ND AND WRN SD DUE TO LOW CLDS AND FOG. THESE CONDS SHOULD CONT THROUGH TONIGHT BEFORE LIFTING ON TUESDAY. ELSEWHERE ACRS NE WY/WRN NEB AND THE BLACK HILLS VFR CONDS ARE EXPECTED TO CONT THROUGH THE FCST PERIOD. && .UNR...WATCHES/WARNINGS/ADVISORIES... .SD...NONE. .WY...NONE. $$ HELGESON sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 852 PM EST SUN DEC 26 2004 .DISCUSSION...LOW CLOUD DECK HAS NOW THICKENED ACROSS THE NORTHERN SECTIONS OF THE FORECAST AREA WHERE MOSTLY CLOUDY SKIES ARE STILL OCCURRING. RUC AND MESOETA INDICATING WEAK VORTICITY MAXIMUM ELONGATED OVER THE NORTHERN FORECAST AREA WITH SOME LINGERING LOW LEVEL MOISTURE. DRYING SHOULD TAKE PLACE SHORTLY AFTER MIDNIGHT AS THE VORT MAX MOVES OUT. NOT SURE IF WILL DROP DOWN TO FORECAST LOWS AS TEMPERATURES ARE STILL IN THE MID 30S. DEWPOINTS THOUGH ARE NEAR FORECAST MINIMUMS AND WITH ALMOST 11 MORE HOURS OF DARKNESS WILL KEEP LOWS AS IS. ONLY CHANGE WILL BE TO ADJUST CLOUD COVER UP ACROSS THE NORTHEAST HALF OF FORECAST AREA. && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ TD tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 435 AM EST MON DEC 27 2004 .DISCUSSION...LARGER SCALE PATTERN FOR THE WEEK FORECAST TO BE IN A STATE OF TRANSITION (INCREASE IN HEMISPHERIC WAVE NUMBER)...END RESULT LOOKS TO BE AN OVERALL SHIFT IN THE LONG WAVE POSITION WEST OF THE GREAT LAKES. SOUTHERN BRANCH OF CURRENT SPLIT FLOW PATTERN IMPINGING ON THE GREAT LAKES LOOKS TO BRING AN OVERALL MODERATING TREND TO THE RECENT COLD SPELL. COUPLE OF SHORT WAVES IN THE NORTHERN STREAM WILL REMAIN NORTH OF THE AREA...WITH MAIN WEATHER FOCUS (OTHER THAN THE USUAL SMALL SCALE NONSENSE LOCALLY) ON EVOLUTION OF STRONG STORM DIGGING SOUTH ALONG THE CA COAST THIS MORNING...AS IT EVENTUALLY GETS KICKED IN OUR DIRECTION DURING THE LATTER HALF OF THE WEEK BY SHORT WAVE TROUGH CURRENTLY ALONG 165W. FIRST ORDER OF BUSINESS WILL BE DEALING WITH BAND OF WAA SYNOPTIC SNOW SPREADING IN FROM THE UPPER MIDWEST THIS AFTERNOON/EVENING... AND ENHANCEMENT POTENTIAL IN SOUTHWEST FLOW FAVORED AREAS. WAA CONTINUES TUESDAY THOUGH MOIST LAYER BECOMES CONSIDERABLY MORE SHALLOW...SO WILL NEED TO EVALUATE PRECIP CHANCES WITH THIS SETUP. TODAY/TONIGHT...INITIAL PROBLEM WILL BE WITH CURRENT RESIDUAL LES THIS MORNING DRIFTING IN OFF LAKE HURON ALONG US-23 FROM THE STRAITS DOWN TO ROGERS CITY...AS WELL AS LAND BREEZE CONVERGENCE BAND WHICH STARTS NEAR LITTLE TRAVERSE BAY AND EXTENDS BACK SOUTHWEST INTO WESTERN LAKE MICHIGAN. MESOSCALE CIRCULATIONS WILL DOMINATE FOR MUCH OF THE MORNING AS LOW LEVEL FLOW HAS SLACKED OFF (1000-850MB WINDS BELOW 10KTS). EXPECT LAKE HURON SNOW SHOWERS TO EVENTUALLY PUSH BACK FARTHER OUT INTO THE LAKE...WHILE NORTHERN LAKE MICHIGAN BAND WILL LIKELY START TO GET ADVECTED NORTH AS LOW LEVEL FLOW VEERS AROUND TO THE SOUTH/SOUTHWEST. NEXT ISSUE WILL BE THE EVENTUAL EVOLUTION OF THIS BAND...WITH THE CONCERN OF BOTH ETA/RUC SHOWING FOCUSED LOW LEVEL CONVERGENCE OVER NORTHERN LAKE MICHIGAN INTO THIS AFTERNOON AS LOW LEVEL FLOW GRADUALLY INCREASES ONCE AGAIN. BUT THIS MAY FOCUS A SINGLE BAND OF SNOW INTO PORTIONS OF MACKINAC COUNTY AND IN THE STRAITS AREA...WHICH WILL BE ENHANCED BY ARRIVAL OF MID LEVEL MOISTURE FROM THE NORTHWEST LATER THIS AFTERNOON. WILL GO AHEAD AND PUT UP AN ADVISORY FOR MACKINAC COUNTY FOR TODAY GIVEN THE POTENTIAL FOR SEVERAL HOURS OF DECENT SNOWFALL. THIS MAY EVENTUALLY NEED TO BE EXTENDED INTO THE TIP OF THE MITT COUNTIES THIS AFTERNOON IF ENHANCED SNOWFALL CREEPS INTO EMMET/CHEBOYGAN COUNTIES. FARTHER INLAND...CLEAR SKIES TO START WILL GIVE WAY TO INCREASING MID CLOUD AS THE DAY WEARS ON. LOW LEVELS ARE PRETTY DRY UPSTREAM (850MB DEW POINT DEPRESSIONS AOA 25C FROM 00Z SOUNDINGS AT MPX/INL/DVN/ILX)...AND THIS DRIER AIR WILL ADVECT INTO THE AREA LATER THIS MORNING. SO INLAND AREAS WILL KEEP CHANCE POPS FOR THE AFTERNOON BASICALLY ALONG/WEST OF I-75 AS INITIAL AREA OF WAA SNOW UPSTREAM WILL NEED TO SATURATE THE LOWER LAYERS FIRST...WILL JUST MENTION FLURRIES OF MUCH OF NORTHEAST LOWER. THIS REGIME CONTINUES INTO TONIGHT...CONTINUED WEAK ISENTROPIC ASCENT THOUGH WITH LITTLE QG ENHANCEMENT OVERALL...AND A GRADUALLY DRYING OF THE MID LEVELS AS THE NIGHT WEARS ON. SO WILL CONTINUE TO FOCUS HIGHER POPS NEAR LAKE MICHIGAN AS SOUTHWEST FLOW CONTINUES...THOUGH WARMING 850MB TEMPERATURES AND FALLING INVERSION HEIGHTS WILL REDUCE THE THREAT FOR SIGNIFICANT ENHANCEMENT AS THE NIGHT WEARS ON. WILL HAVE A COUPLE INCHES ACCUMULATION CENTERED AROUND THE STRAITS TONIGHT... LESS THAN AN INCH ELSEWHERE. MARINE...INCREASING SOUTHWEST FLOW MAY END UP PUSHING SCA CRITERIA ON THE LAKE MICHIGAN LATER TODAY INTO TONIGHT...AS WELL AS FROM THE STRAITS EAST TO FALSE DETOUR CHANNEL ON THE LAKE HURON SIDE. TUESDAY...GOOD DEAL OF MOISTURE REMAINS BELOW 750MB (AND BETWEEN 0 AND -10C ISOTHERMS)...ALONG WITH SOME WEAK BUT PERSISTENT ISENTROPIC ASCENT WITHIN THE MOIST LAYER. WILL ALSO BE SOME SHALLOW CONVECTION OVER THE LAKES WITH 925MB TEMPERATURES STILL AROUND -5C (WATER TEMPERATURE AROUND 6C). SO SOME POTENTIAL THERE FOR FLURRIES OR PERHAPS SOME DRIZZLE/FREEZING DRIZZLE. GFS TRYING TO PULL AN AXIS OF MID LEVEL MOISTURE BACK ACROSS SOUTHERN/CENTRAL LOWER LATER TUESDAY...NOT SURE HOW REALISTIC THIS IS BUT WILL MAINTAIN A LOW CHANCE POP FOR SNOW SOUTH OF M-72 TO ACCOUNT FOR A LITTLE BETTER PROBABILITY OF MEASURABLE PRECIP. WEAKENING COLD FRONT DROPS IN FROM THE NORTH TUESDAY NIGHT...MOISTURE REMAINS SHALLOW THOUGH TEMPERATURES COOL A BIT IN THE LOWER LEVELS (850MB TEMPERATURES BACK DOWN TO -10C OVER LAKE SUPERIOR WITH FLOW VEERING NORTHWEST). WITH THE EXCEPTION OF FAVORED WESTERLY FLOW AREAS...WHERE WILL MAINTAIN LOW CHANCE POPS FOR SNOW SHOWERS...WILL ONLY CARRY FLURRIES/FREEZING DRIZZLE ELSEWHERE. MARINE...SCA CONDITIONS WILL LIKELY CONTINUE IN AREAS OUTLINED ABOVE THROUGH THE DAY TUESDAY BEFORE GRADIENT WEAKENS TUESDAY NIGHT AS WEAKENING COLD FRONT DROPS IN FROM THE NORTH. JPB WEDNESDAY AND EXTENDED PERIODS...ETA/GFS SOLUTIONS DEPICTING THE CLOSED LOW NOW MIGRATING DOWN THE CA COAST OPENING AND PROGRESSING INTO THE PLAINS...LEADING TO DOWNSTREAM WEAK UPPER RIDGING AND SFC HIGH PRESSURE BUILDING ACROSS THE WESTERN GREAT LAKES LATER IN THE DAY. ETA CONTINUES TO BE MORE BULLISH WITH THE DEGREE OF RIDGING AND WARM AIR NUDGING UP INTO THE STATE (RUNNING 2-4C WARMER AT 850MB VS THE GFS). BUT GIVEN THE TIME OF YEAR WILL GO MORE WITH THE COLDER GFS IDEA WHICH KEEPS 850MB TEMPS COLD ENOUGH FOR LAKE EFFECT UNTIL LATER IN THE DAY. WILL NEED TO ADDRESS WEAK COLD FRONT DROPPING THROUGH NORTHERN MICHIGAN PRIOR TO THE SFC HIGH BUILDING INTO THE REGION. ALTHOUGH...APPEARS LACK OF DEEPER MOISTURE AND FORCING WILL PRECLUDE MUCH (IF ANY) SYNOPTIC PRECIP WITH THIS FEATURE...LOW LEVEL CONVERGENCE ALONG THE FRONT MAY BE ENOUGH TO GENERATE SOME SNOW SHOWERS OFF LAKES SUPERIOR AND MICHIGAN FOR THE W/WNW FLOW AREAS...AT LEAST DURING THE MORNING HOURS BEFORE MUCH DRIER AIR AND RIDGING BUILD IN. WEDNESDAY NIGHT THROUGH THURSDAY...OPEN WAVE MENTIONED ABOVE ALONG WITH ASSOCIATED DEEPENING SFC LOW STILL FORECAST TO MIGRATE OUT OF THE PLAINS AND INTO THE GREAT LAKES DURING THIS TIME. ETA/GFS BOTH FORECAST STRONG WARM ADVECTION DEVELOPING ACROSS THE WESTERN GREAT LAKES BY THURSDAY PUSHING >0C 850MB TEMPS/DEEPER MOISTURE/AND AN ABOVE FREEZING WARM LAYER >= 7K FEET (PER GFS SOUNDINGS) INTO NORTHERN MICHIGAN DURING THE DAY ON THURSDAY...FASTER THAN PREVIOUS FORECASTS. UPSHOT TO ALL THIS...HAVE BUMPED UP TIMING FOR PRECIP CHANCES TO THURSDAY PER COLLABORATION OF SURROUNDING OFFICES. AND BASED ON GFS SOUNDINGS...RIGHT NOW LOOKING LIKE PRIMARILY A RAIN EVENT FOR THE ENTIRE CWA WITH SOME RAIN/SNOW MIX POTENTIAL ACROSS THE EASTERN U.P. EARLY THURSDAY. BUT THIS FAR OUT...ADJUSTMENTS TO PTYPE CERTAINLY LIKELY AS WE APPROACH THE EVENT. ALSO...WITH COMMENCEMENT OF STRONG WARM/MOISTURE ADVECTION IN THE LOWER LEVELS WEDNESDAY NIGHT AND SFC DEWPOINTS PUSHING UP TO AROUND 30F WED NIGHT AND FURTHER INTO THE MID/UPPER 30S ON THURSDAY (OVER THE SNOWPACK)...ADDED FOG MENTION TO FORECASTS BEGINNING WED NIGHT. ADAM && .APX...WATCHES/WARNINGS/ADVISORIES...SNOW ADVISORY...TODAY...MIZ015. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 330 AM EST MON DEC 27 2004 .SHORT TERM... SATELLITE IMAGERY AND SURFACE ANALYSES SHOW HIGH PRESSURE BEGINNING TO HAVE AN IMPACT ON LAKE CLOUDS, SNOW SHOWERS, AND FOG PATTERN. EXPECT LOW LEVEL FLOW TO CONTINUE BACKING TOWARD THE NORTH AND TAKE THE LAKE EFFECT CLOUDS AND SNOW SHOWERS MORE TO OUR EAST WITH TIME THIS MORNING. NEARLY CALM SURFACE WINDS WILL NOT DO MUCH TO ADVECT THE DRY AIR INTO OUR REGION FROM NORTHERN LOWER, SO THERE IS A CHANCE THAT FOG WILL HOLD ON SOUTH OF THE TRI CITIES AND EXPAND INTO THE DETROIT AREA AS THE SURFACE RIDGE BUILDS OVERHEAD AROUND SUNRISE. DO NOT ANTICIPATE A HEADLINE FOR THE FOG GIVEN THE PACE OF VISIBILITY CHANGES SO FAR THIS MORNING, BUT WE'LL MONITOR. VARYING AMOUNTS OF FOG AND CLOUD COVER AFTER SUNRISE WILL COMBINE WITH STEADILY INCREASING HIGH CLOUDS DURING THE DAY TO MAKE THE TEMP FORECAST COMPLICATED. MID LEVEL WARM ADVECTION WILL CARRY IN THE CIRRUS AND ALTOSTRATUS, ESPECIALLY THIS AFTERNOON, AS THE SURFACE RIDGE SLOWLY MOVES EAST. THE CLOUDS, COMBINED WITH A SLOWLY DEVELOPING SOUTH WIND, WILL MAKE THE MID 20S OFFERED BY GUIDANCE THE HIGH END OF THE RANGE. EXPECT EVENING LOWS AND THEN RISING TEMPS OVERNIGHT TONIGHT. CLOUDS WILL THICKEN AND LOWER AND THE WIND WILL INCREASE INTO THE 10 TO 20 MPH RANGE TO HELP HOIST THE TEMPS TOWARD SUNRISE. MODEL SOUNDINGS AND CROSS SECTIONS SUGGEST THAT THETA-E ADVECTION WILL STRUGGLE TO PRODUCE ANY SNOW BEFORE SUNRISE. MID LEVEL MOISTURE PROFILES DO NOT SHOW VERY CONSISTENT SATURATION ABOVE THE BOUNDARY LAYER. EVEN THE USUALLY GENEROUS GFS IS LEAN ON QPF BY 12Z TUESDAY, SO A CHANCE OF FLURRIES WILL WORK GOOD FOR THE OVERNIGHT HOURS. && .LONG TERM... (TUESDAY-SUNDAY) TUESDAY... MODELS IN GENERAL AGREEMENT WITH BRINGING THE LARGE SURFACE HIGH TOWARD THE MIDDLE ATLANTIC COAST BY EVENING AS WEAKENING COLD FRONT APPROACHES THE WESTERN LAKES. AT 500MB, WE OBSERVE A FAIR AMOUNT OF CONFLUENCE AS WARM ADVECTION BEGINS TO UNFOLD UPSTREAM AND MAKE SOME INROADS. WITH THAT SAID, NOT SURE WHY THE GFS IS OVER-GENEROUS WITH ITS QPF ACROSS THE STATE ON TUESDAY AS IT IS THE ONLY MODEL (COMPARED TO THE ETA, CANADIAN, NGM, RUC13, UKMET) SUGGESTING ACCUMULATING SNOWFALL. FORECAST SOUNDINGS REVEAL A DISCONNECT IN THE MOISTURE PROFILES AND OVERALL LIFT IS LESS THAN IMPRESSIVE. IN ADDITION, WITH WARMING 850MB TEMPS (GOING ABOVE 0C) WE FEEL LAKE MICHIGAN CONTRIBUTION WILL BE MINIMAL. WE WILL RETAIN THE CHANCE OF LIGHT SNOW BUT DROP THE POPS TO 30%. THE FRONTAL BOUNDARY WILL BECOME DRAPED ACROSS LAKE HURON TUESDAY NIGHT AS IT BECOMES PARALLEL TO THE FLOW ALOFT FURTHER REDUCE ITS DEFINITION OVERNIGHT. STILL A BIT CONCERNED WITH SOME FOG DEVELOPING ACROSS THE TRI-CITIES AND THUMB AS LIGHT SURFACE FLOW, WEAK CONVERGENCE WITH AFOREMENTIONED FRONT, AND SOME WARM ADVECTION. 30AGL CPD/S SHOW THIS REGION DROPPING BELOW 30MBS PER THE ETA/GFS YET THEIR MOS VALUES SHOW NO HINT OF THIS (USUALLY, MOS DOES OFFER SOME GUIDANCE ON FOG POTENTIAL). THEREFORE, WE WILL HOLD OFF THE MENTION OF FOG BUT RETAIN THE CHANCE OF SOME FLURRIES WITH THE WARM ADVECTION AND RESULTING WEAK LIFT. WEDNESDAY... HEIGHTS RISE QUICKLY ACROSS THE GREAT LAKES THRU THE DAY BUT SOUNDINGS SHOW QUITE A BIT OF MOISTURE HANGING AROUND BELOW THE WARMING COLUMN ALOFT. THEREFORE, WE WILL SEE LIMITED SUNSHINE AND THIS WILL TAKE A TOLL ON THE SURFACE TEMPS. GUIDANCE NUMBERS STILL LOOK A TAD WARM AND WITH OUR CURRENT SNOWPACK AND PLENTY OF THAT UPSTREAM FROM US... WE WILL CLIMB ABOVE FREEZING BUT NOT BY MUCH. THE MAIN SHOW IN TERMS OF WARM ADVECTION ARRIVES WEDNESDAY NIGHT. IMPRESSIVE 850MB TEMP RECOVERY AS WE ARE EXPECTED TO CLIMB WELL INTO POSITIVE TERRITORY UPSTREAM AND WITH INCREASE LLJ IN EXCESS OF 50KTS, IT WILL NOT TAKE TOO LONG FOR US TO FEEL THE BENEFITS. HOWEVER, THIS WILL BRING ABOUT THE POTENTIAL FOR AN ADVECTION FOG REGIME AS SURFACE DEWPOINTS ARE EXPECTED TO CLIMB AOB FREEZING. THURSDAY... STRONG PIECE OF ENERGY EJECTS FROM THE PACIFIC UPPER LOW WITH STRONG CYCLOGENESIS LEE OF THE ROCKIES ACROSS THE PLAINS. THIS WILL ALLOW FOR A STRENGTHENING SOUTHERLY FLOW AND BRING ABOUT A CHANCE FOR RAIN (YES, RAIN). WITH 1000-850MB THICKNESSES CLIMBING WELL INTO THE 1300'S AND 850MB TEMPS PROGGED TO CLIMB TO BETWEEN +5/+8C...IT WILL BE ALL RAIN. QUESTION WILL BE WHERE THE CONCENTRATION OF RAINFALL WILL OCCUR. WHILE ISENTROPIC LIFT, AS ONE WOULD EXPECT, IS VERY IMPRESSIVE... THE LOWER CPD VALUES ARE ACROSS NORTHERN LOWER. STILL PLENTY OF TIME TO MAKE ADJUSTMENTS BUT AT THE MINIMUM WE WILL ADD THE CHANCE FOR RAIN. THE SYSTEM FILLS ACROSS THE GREAT LAKES BY WEEKS END WHICH SHOULD SLOW DOWN THE COLD AIR FILTERING SOUTH ONCE AGAIN BY THIS WEEKEND. .DTX WATCHES/WARNINGS/ADVISORIES... .MI...NONE. .LAKE HURON...NONE. .LAKE ST CLAIR...NONE. .MI WATERS OF LAKE ERIE...NONE. && $$ BT/BGM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 328 AM EST MON DEC 27 2004 .DISCUSSION... MAIN FORECAST CONCERN IS SNOW POTENTIAL TODAY AND THEN THE SYSTEM FOR THE THURSDAY-FRIDAY TIME FRAME. CURRENT WEATHER...09Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED AN UPPER LEVEL TROUGH OVER THE NORTHEAST U.S....RIDGING ACROSS THE CENTRAL PART OF THE COUNTRY AND A BIG UPPER LEVEL LOW OFF THE COAST OF CALIFORNIA. TWO SHRTWV TROUGHS WERE LOCATED TO THE NW OF UPPER MICHIGAN...ONE OVER NW ONTARIO AND ONE OVER THE NW TERRITORIES. IR SATELLITE IMAGERY SHOWED CLOUDS AHEAD OF THE SHRTWV TROUGH OVER NW ONTARIO STRETCHING DOWN INTO NORTHERN MN. SOME -SN REPORTED OUT OF THESE CLOUDS. THERE WAS ALSO A BAND OF MID-LEVEL CLOUDS STRETCHING FROM WESTERN WISCONSIN TO SOUTHERN MN AND THE DAKOTAS. THIS BAND HAS BEEN SUPPORTED BY ISENTROPIC LIFT AND THE TOP OF THE CENTRAL U.S. RIDGE. 00Z ABR SOUNDING WAS ALMOST COMPLETELY MOIST IN THE TROPOSPHERE WHEREAS THE MPX SOUNDING HAD DEWPOINT DEPRESSIONS OF 15-30C FROM 900-600MB. CLOSER TO HOME...SOME LAKE EFFECT SNOW SHOWERS REMAIN ON LAKES SUPERIOR AND MICHIGAN...THOUGH THESE HAVE GREATLY DIMINISHED DUE TO THE DRY AIR AND LIGHT WINDS ASSOCIATED WITH A 1038MB HIGH OVER THE REGION. THIS HIGH ALSO ALLOWED SKIES TO CLEAR OUT LAST NIGHT WITH TEMPERATURES FALLING TO 10 BELOW ZERO IN MANY LOCATIONS. ALSO AT THE SURFACE...A COLD FRONT WAS LOCATED OVER NW ONTARIO ASSOCIATED WITH THE SHRTWV TROUGH AND A 1036MB HIGH WAS LOCATED BEHIND THE FRONT OVER SOUTHERN SASKATCHEWAN. TODAY...SHRTWV TROUGH OVER NORTHERN ONTARIO MOVES INTO QUEBEC...DRAGGING THE WEAK COLD FRONT TOWARDS UPPER MICHIGAN. IN FACT...BOTH THE ETA AND THE GFS SHOW THIS FRONT DISSIPATING AS PRESSURES FALL BACK TO THE WEST ASSOCIATED WITH THE NEXT SHRTWV TROUGH MOVING THROUGH CENTRAL CANADA. SO LITTLE IN THE WAY OF DPVA IS EXPECTED. HOWEVER...THE ISENTROPIC LIFT SUPPORTING THE BAND OF CLOUDS TO OUR WEST AND SOUTHWEST WILL MOVE UP INTO UPPER MICHIGAN THIS AFTERNOON. ONLY PROBLEM IS THAT THE LOW LEVELS MAY TAKE AWHILE TO MOISTEN UP AS SEEN WITH THE DRY AIR ON THE 00Z MPX SOUNDING. THEREFORE NOT NEARLY AS EXCITED ABOUT PRECIPITATION AS YESTERDAY AND NEITHER ARE THE MODELS. QPF NOW FROM BOTH THE GFS AND ETA ARE ONLY A FEW HUNDREDTHS...WITH THE MOST ALONG THE WISCONSIN BORDER WHERE THE LOW-LEVELS HAVE THE BEST PROBABILITY OF MOISTENING UP. THERE IS ALSO POTENTIAL FOR LAKE EFFECT FROM LAKE MICHIGAN WITH WINDS TURNING TO THE SW AND 850MB-SFC DELTA-T\S BETWEEN 15 AND 20...BUT THE FLOW TURNS TOO SOUTHWESTERLY BY LATE MORNING TO IMPACT MUCH OF SCHOOLCRAFT COUNTY. TEMPERATURES SHOULD BE WARMER THAN YESTERDAY WITH THE SOUTHWESTERLY FLOW...HIGHER 850MB TEMPS AND POSSIBILITY OF A LITTLE SUN IN THE MORNING. FOLLOWED CLOSE TO MET GUIDANCE. TONIGHT...UPPER MICHIGAN REMAINS IN SOUTHWESTERLY LOW LEVEL FLOW AS THE HIGH PRESSURE RIDGE THAT IS CURRENTLY OVER UPPER MICHIGAN MOVES INTO THE CAROLINAS. MEANWHILE ANOTHER COLD FRONT MOVES INTO ONTARIO ASSOCIATED WITH THE SECOND SHRTWV TROUGH MENTIONED BEFORE. DESPITE ISENTROPIC LIFT THROUGH THE NIGHT...LACK OF ANY DYNAMICAL FORCING WILL KEEP ANY PRECIPITATION REALLY LIGHT. IN FACT NEITHER THE GFS OR ETA SHOW MUCH IN THE WAY OF QPF...ESPECIALLY SINCE MOST OF THE MID LEVEL MOISTURE APPEARS TO LEAVE THE AREA. HOWEVER...THERE IS PLENTY OF LOW LEVEL MOISTURE (PARTICULARLY BELOW 5000 FT) AND TEMPERATURES IN THAT LAYER ARE AROUND -10C. SO WILL MENTION SOME FLURRIES. AS MENTIONED IN THE PREVIOUS AFD...SHOULD THESE TEMPERATURES WARM A FEW DEGREES WE COULD BE DEALING WITH FREEZING DRIZZLE. WITH PLENTY OF CLOUDS AROUND AND THE SW FLOW...TEMPERATURES SHOULD NOT FALL TOO MUCH FROM DAYTIME HIGHS. LIKE THE MET GUIDANCE WITH TEMPS ONLY FALLING 5 TO 10 DEGREES. TUESDAY...AS THE SHRTWV TO OUR NORTH CONTINUES ACROSS NORTHERN ONTARIO...THE ASSOCIATED COLD FRONT MOVES INTO UPPER MICHIGAN BY 21Z. HOWEVER...WITH 1019MB HIGH PRESSURE BEHIND THE FRONT...THE COLD ADVECTION DOES NOT NEARLY LOOK AS IMPRESSIVE. AHEAD OF THE FRONT THOUGH...THE ETA SHOWS 850MB TEMPS RISING TO 0C ALONG THE BORDER COUNTIES. THIS WARM AIR WILL ALSO BE A RESULT OF THE ISENTROPIC LIFT OCCURRING WHICH WILL NOT HELP TO ERODE THE LOW LEVEL MOISTURE. SO WE WILL NOT BE REALIZING THE FULL EXTENT OF THIS WARMING HOWEVER TEMPERATURES WILL BE WARMER THAN TODAY. AS FOR PRECIPITATION...WILL LEAVE IN A FEW FLURRIES INTO THE MORNING...THEN AS LOW LEVELS WARM...WE MAY BE DEALING WITH FREEZING DRIZZLE INSTEAD. THE PROBLEM IS THAT THE HIGH LOW LEVEL MOISTURE LAYER CONTINUES TO DECREASE IN HEIGHT WHICH MAY GET TOO SMALL TO ALLOW PRECIPITATION. TUESDAY NIGHT...UPPER LOW OFF OF THE CALIFORNIA COAST BEGINS TO MOVE INLAND ALONG THE NORTHERN BAJA PENINSULA...ALLOWING RIDGING TO STRENGTHEN OVER THE PLAINS AND PRESSURES TO FALL ALONG THE LEE OF THE ROCKIES. MEANWHILE CLOSER TO HOME...THE SURFACE COLD FRONT MOVES SLOWLY THROUGH THE U.P. AS IT BEGINS TO ORIENT ITSELF PARALLEL TO THE UPPER FLOW. BY 12Z WED...THE FRONT IS PROGGED TO BE ALONG THE SOUTHERN U.P. BORDER. MAIN QUESTION HERE IS HOW COLD TEMPERATURES WILL FALL BEHIND THE FRONT AS THE BETTER COLD ADVECTION IS FURTHER TO THE NORTH. THE GFS SHOWS 850MB TEMPS FALLING TO -8 TO -10C WHICH IS SUFFICIENTLY COLD FOR LAKE EFFECT ALONG THE NORTHWEST SNOWBELTS. HOWEVER...THE ETA IS WARMER WITH 850MB TEMPS ONLY AROUND -6C WHICH IS NOT COLD ENOUGH. WILL LEAVE A 30 PERCENT CHANCE OF SNOW IN FOR THE NORTHWEST SNOWBELTS...BUT THIS MAY NEED TO BE REMOVED IN LATER SHIFTS IF THE ETA DOES PAN OUT. AWAY FROM THE LAKE EFFECT...THE COLD AIR MOVING IN SHOULD HELP TO REMOVE THE FREEZING DRIZZLE POSSIBILITY AND KEEP EVERYTHING AS FLURRIES. WEDNESDAY...NOT MUCH GOING ON OVER UPPER MICHIGAN AS A BUBBLE HIGH MOVES OVERHEAD BEHIND THE TUESDAY NIGHT COLD FRONT. 850MB TEMPS RISING BACK TO -2C AND A LIGHT SOUTHERLY WIND MAY MAKE IT APPEAR THAT IT WILL BE A WARM DAY. HOWEVER SOUNDINGS STILL SHOW THAT MOISTURE STUCK BELOW 925 MB AS THE WARMING AND DRYING ALOFT HELPS STRENGTHEN THE INVERSION. WITH THE SUN ANGLE AT ITS LOWEST POINT OF THE YEAR AND THAT LIGHT SOUTH WIND...DO NOT SEE MUCH POTENTIAL IN MIXING THAT LOW LEVEL MOISTURE OUT EITHER. HOWEVER...AT LEAST THE FLURRIES/DRIZZLE WILL STOP AS THE LAYER OF MOISTURE IS NOT NEARLY AS THICK. ATTENTION THEN FOCUSES TO THE WESTERN UNITED STATES FOR THE NEXT SYSTEM. UPPER LOW CONTINUES INLAND AND BEGINS TO SHEAR OUT AS ANOTHER BIG UPPER LOW DROPS DOWN THE WEST COAST. MAJOR DIFFERENCES OCCUR HERE BETWEEN THE MODELS ON WHERE THE SHEARED OUT UPPER LOW GOES. HPC PREFERENCE WHICH I WILL FOLLOW FROM HERE ONWARDS IS THE CANADIAN/UKMET WHICH HAVE THE SHEARED OUT LOW OVER SOUTHERN NEVADA AT 00Z THU. A SURFACE LOW ENDS UP DEVELOPING DOWNSTREAM OF THIS SHRTWV OVER NORTHERN WYOMING WITH A WARM FRONT EXTENDING EASTWARD TO SIOUX FALLS SOUTH DAKOTA. WEDNESDAY NIGHT THROUGH FRIDAY...MAIN STORY IS TRYING TO FIGURE OUT THE TRACK OF THE LOW PRESSURE SYSTEM THAT DEVELOPS OVER THE WEST ON WEDNESDAY. LOW POSITIONS AT 00Z FRI...THE CANADIAN 997MB NEAR MITCHELL SOUTH DAKOTA...THE UKMET 995MB OVER OMAHA NEBRASKA...AND THE GFS 989MB NEAR MINNEAPOLIS. BY 12Z FRI THE CANADIAN HAS A 998MB LOW OVER DLH AND THE GFS 995MB OVER MENOMINEE COUNTY. NO 00Z UKMET POSITION AVAILABLE...BUT INTERPOLATION BETWEEN THE 00Z FRI AND 00Z SAT POSITIONS WOULD HAVE IT OVER MENOMINEE COUNTY. NEW 00Z ECMWF SIMILAR TO THE GFS. THE REASON FOR THE CONCERN ON THE TRACK IS PRECIPITATION TYPE. RIGHT NOW GIVEN THE UNCERTAINTY OF THE TRACK...NO CHANGES WILL BE MADE TO THE FORECAST. HOWEVER WITH THE 00Z UKMET AND GFS TRENDING FURTHER SOUTH...THERE IS INCREASING POTENTIAL FOR PURE SNOW RATHER THAN A MIX OR ALL RAIN. ONE THING THAT MAY NEED TO BE WATCHED TOO IS POTENTIAL FOR FREEZING RAIN AT THE ONSET OF THE PRECIPITATION IF THE FURTHER NORTH POSITIONS PAN OUT. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 930 AM EST MON DEC 27 2004 .SYNOPSIS...UPPER AIR ANALYSIS DEPICTS A DEPARTING LOW OFF THE NEW ENGLAND COAST, LARGE SCALE RIDGE AXIS OVER THE HIGH PLAINS, AND A DEEP LOW OFF THE PACIFIC COAST. SURFACE HIGH PRESSURE CENTERED OVER THE GREAT LAKES RIDGES SWD TO THE NRN GULF OF MEXICO. VERY DRY AIRMASS IN PLACE W/ PRECIP WATER NEAR A 1/4 INCH. GOES VISIBLE IMAGERY DEPICTS A FEW PASSING CIRRUS IN NWLY FLOW. OTHERWISE, SKIES ARE SUNNY. IT WAS ANOTHER COLD START TO THE DAY WITH FREEZING TEMPS AT MOST LOCATIONS. && .SHORT TERM (REST OF TODAY)...SLIGHTLY WARMER 850 MB TEMPS THIS MORNING, WITH HIGHS IN THE 55-60 DEGREE RANGE. NO CHANGES TO THE INHERITED ZONE FORECAST. && .MARINE...WINDS AT BUOY 42036 HAVE DECREASED BELOW CAUTION CRITERION SINCE THE MORNING CWF ISSUANCE. BOTH THE ETA AND RUC AGREE THAT WINDS WILL REMAIN BELOW HEADLINES FOR THE REMAINDER OF THE DAY AS THE PRESSURE GRADIENT RELAXES A BIT. WILL WAIT AND SEE IF THE NEXT HOUR OBSERVATION MAINTAINS THIS TREND. IF SO, WILL LOWER THE HEADLINE ON THE LATE MORNING UPDATE. && .FIRE WEATHER...A RED FLAG WARNING REMAINS IN EFFECT THIS AFTN FOR ALL FL ZONES EXCEPT ALONG THE IMMEDIATE COAST DUE TO FOUR OR MORE CONSECUTIVE HOURS OF RH BELOW 35%. && TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING THIS AFTN FOR ALL EXCEPT THE IMMEDIATE COAST. && $$ MAJ fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1045 AM EST MON DEC 27 2004 .SHORT TERM...SOUTHWEST FLOW WARM AIR ADVECTION SNOW BAND OVER LAKE MICHIGAN EXPECTED TO AFFECT MACKINAC COUNTY AND NORTHWEST MICHIGAN COUNTIES TODAY. ONGOING FORECAST ON TRACK. MID CLOUDS STREAMING INTO NORTHERN LAKE MICHIGAN AT 15Z MAY ENHANCE SNOWFALL IN THIS BAND THIS AFTERNOON AS UPPER MOISTURE PASSES INTO THE FAVORED -15 TO -20 DEGREE RANGE. OVER NORTHERN LOWER...DRY AIR BETWEEN 750 MB AND 850 MB WILL BE HARD TO OVERCOME EARLY THIS AFTERNOON...ALTHOUGH LOW LEVEL MOISTURE WILL INCREASE THROUGHOUT THE DAY. ONGOING LIGHT SNOW OR FLURRIES OVER MUCH OF NORTHERN LOWER STILL LOOKS REASONABLE...ALTHOUGH WOULD NOT EXPECT MUCH UNTIL AFTER 18Z. HIGH TEMPERATURES IN BALL PARK. WILL UPDATE ZONES TO CLEAN UP MORNING WORDING. CAMPBELL && PREVIOUS DISCUSSION ISSUED AT 435 AM DEC 27 TODAY/TONIGHT...INITIAL PROBLEM WILL BE WITH CURRENT RESIDUAL LES THIS MORNING DRIFTING IN OFF LAKE HURON ALONG US-23 FROM THE STRAITS DOWN TO ROGERS CITY...AS WELL AS LAND BREEZE CONVERGENCE BAND WHICH STARTS NEAR LITTLE TRAVERSE BAY AND EXTENDS BACK SOUTHWEST INTO WESTERN LAKE MICHIGAN. MESOSCALE CIRCULATIONS WILL DOMINATE FOR MUCH OF THE MORNING AS LOW LEVEL FLOW HAS SLACKED OFF (1000-850MB WINDS BELOW 10KTS). EXPECT LAKE HURON SNOW SHOWERS TO EVENTUALLY PUSH BACK FARTHER OUT INTO THE LAKE...WHILE NORTHERN LAKE MICHIGAN BAND WILL LIKELY START TO GET ADVECTED NORTH AS LOW LEVEL FLOW VEERS AROUND TO THE SOUTH/SOUTHWEST. NEXT ISSUE WILL BE THE EVENTUAL EVOLUTION OF THIS BAND...WITH THE CONCERN OF BOTH ETA/RUC SHOWING FOCUSED LOW LEVEL CONVERGENCE OVER NORTHERN LAKE MICHIGAN INTO THIS AFTERNOON AS LOW LEVEL FLOW GRADUALLY INCREASES ONCE AGAIN. BUT THIS MAY FOCUS A SINGLE BAND OF SNOW INTO PORTIONS OF MACKINAC COUNTY AND IN THE STRAITS AREA...WHICH WILL BE ENHANCED BY ARRIVAL OF MID LEVEL MOISTURE FROM THE NORTHWEST LATER THIS AFTERNOON. WILL GO AHEAD AND PUT UP AN ADVISORY FOR MACKINAC COUNTY FOR TODAY GIVEN THE POTENTIAL FOR SEVERAL HOURS OF DECENT SNOWFALL. THIS MAY EVENTUALLY NEED TO BE EXTENDED INTO THE TIP OF THE MITT COUNTIES THIS AFTERNOON IF ENHANCED SNOWFALL CREEPS INTO EMMET/CHEBOYGAN COUNTIES. FARTHER INLAND...CLEAR SKIES TO START WILL GIVE WAY TO INCREASING MID CLOUD AS THE DAY WEARS ON. LOW LEVELS ARE PRETTY DRY UPSTREAM (850MB DEW POINT DEPRESSIONS AOA 25C FROM 00Z SOUNDINGS AT MPX/INL/DVN/ILX)...AND THIS DRIER AIR WILL ADVECT INTO THE AREA LATER THIS MORNING. SO INLAND AREAS WILL KEEP CHANCE POPS FOR THE AFTERNOON BASICALLY ALONG/WEST OF I-75 AS INITIAL AREA OF WAA SNOW UPSTREAM WILL NEED TO SATURATE THE LOWER LAYERS FIRST...WILL JUST MENTION FLURRIES OF MUCH OF NORTHEAST LOWER. THIS REGIME CONTINUES INTO TONIGHT...CONTINUED WEAK ISENTROPIC ASCENT THOUGH WITH LITTLE QG ENHANCEMENT OVERALL...AND A GRADUALLY DRYING OF THE MID LEVELS AS THE NIGHT WEARS ON. SO WILL CONTINUE TO FOCUS HIGHER POPS NEAR LAKE MICHIGAN AS SOUTHWEST FLOW CONTINUES...THOUGH WARMING 850MB TEMPERATURES AND FALLING INVERSION HEIGHTS WILL REDUCE THE THREAT FOR SIGNIFICANT ENHANCEMENT AS THE NIGHT WEARS ON. WILL HAVE A COUPLE INCHES ACCUMULATION CENTERED AROUND THE STRAITS TONIGHT... LESS THAN AN INCH ELSEWHERE. MARINE...INCREASING SOUTHWEST FLOW MAY END UP PUSHING SCA CRITERIA ON THE LAKE MICHIGAN LATER TODAY INTO TONIGHT...AS WELL AS FROM THE STRAITS EAST TO FALSE DETOUR CHANNEL ON THE LAKE HURON SIDE. TUESDAY...GOOD DEAL OF MOISTURE REMAINS BELOW 750MB (AND BETWEEN 0 AND -10C ISOTHERMS)...ALONG WITH SOME WEAK BUT PERSISTENT ISENTROPIC ASCENT WITHIN THE MOIST LAYER. WILL ALSO BE SOME SHALLOW CONVECTION OVER THE LAKES WITH 925MB TEMPERATURES STILL AROUND -5C (WATER TEMPERATURE AROUND 6C). SO SOME POTENTIAL THERE FOR FLURRIES OR PERHAPS SOME DRIZZLE/FREEZING DRIZZLE. GFS TRYING TO PULL AN AXIS OF MID LEVEL MOISTURE BACK ACROSS SOUTHERN/CENTRAL LOWER LATER TUESDAY...NOT SURE HOW REALISTIC THIS IS BUT WILL MAINTAIN A LOW CHANCE POP FOR SNOW SOUTH OF M-72 TO ACCOUNT FOR A LITTLE BETTER PROBABILITY OF MEASURABLE PRECIP. WEAKENING COLD FRONT DROPS IN FROM THE NORTH TUESDAY NIGHT...MOISTURE REMAINS SHALLOW THOUGH TEMPERATURES COOL A BIT IN THE LOWER LEVELS (850MB TEMPERATURES BACK DOWN TO -10C OVER LAKE SUPERIOR WITH FLOW VEERING NORTHWEST). WITH THE EXCEPTION OF FAVORED WESTERLY FLOW AREAS...WHERE WILL MAINTAIN LOW CHANCE POPS FOR SNOW SHOWERS...WILL ONLY CARRY FLURRIES/FREEZING DRIZZLE ELSEWHERE. MARINE...SCA CONDITIONS WILL LIKELY CONTINUE IN AREAS OUTLINED ABOVE THROUGH THE DAY TUESDAY BEFORE GRADIENT WEAKENS TUESDAY NIGHT AS WEAKENING COLD FRONT DROPS IN FROM THE NORTH. JPB WEDNESDAY AND EXTENDED PERIODS...ETA/GFS SOLUTIONS DEPICTING THE CLOSED LOW NOW MIGRATING DOWN THE CA COAST OPENING AND PROGRESSING INTO THE PLAINS...LEADING TO DOWNSTREAM WEAK UPPER RIDGING AND SFC HIGH PRESSURE BUILDING ACROSS THE WESTERN GREAT LAKES LATER IN THE DAY. ETA CONTINUES TO BE MORE BULLISH WITH THE DEGREE OF RIDGING AND WARM AIR NUDGING UP INTO THE STATE (RUNNING 2-4C WARMER AT 850MB VS THE GFS). BUT GIVEN THE TIME OF YEAR WILL GO MORE WITH THE COLDER GFS IDEA WHICH KEEPS 850MB TEMPS COLD ENOUGH FOR LAKE EFFECT UNTIL LATER IN THE DAY. WILL NEED TO ADDRESS WEAK COLD FRONT DROPPING THROUGH NORTHERN MICHIGAN PRIOR TO THE SFC HIGH BUILDING INTO THE REGION. ALTHOUGH...APPEARS LACK OF DEEPER MOISTURE AND FORCING WILL PRECLUDE MUCH (IF ANY) SYNOPTIC PRECIP WITH THIS FEATURE...LOW LEVEL CONVERGENCE ALONG THE FRONT MAY BE ENOUGH TO GENERATE SOME SNOW SHOWERS OFF LAKES SUPERIOR AND MICHIGAN FOR THE W/WNW FLOW AREAS...AT LEAST DURING THE MORNING HOURS BEFORE MUCH DRIER AIR AND RIDGING BUILD IN. WEDNESDAY NIGHT THROUGH THURSDAY...OPEN WAVE MENTIONED ABOVE ALONG WITH ASSOCIATED DEEPENING SFC LOW STILL FORECAST TO MIGRATE OUT OF THE PLAINS AND INTO THE GREAT LAKES DURING THIS TIME. ETA/GFS BOTH FORECAST STRONG WARM ADVECTION DEVELOPING ACROSS THE WESTERN GREAT LAKES BY THURSDAY PUSHING >0C 850MB TEMPS/DEEPER MOISTURE/AND AN ABOVE FREEZING WARM LAYER >= 7K FEET (PER GFS SOUNDINGS) INTO NORTHERN MICHIGAN DURING THE DAY ON THURSDAY...FASTER THAN PREVIOUS FORECASTS. UPSHOT TO ALL THIS...HAVE BUMPED UP TIMING FOR PRECIP CHANCES TO THURSDAY PER COLLABORATION OF SURROUNDING OFFICES. AND BASED ON GFS SOUNDINGS...RIGHT NOW LOOKING LIKE PRIMARILY A RAIN EVENT FOR THE ENTIRE CWA WITH SOME RAIN/SNOW MIX POTENTIAL ACROSS THE EASTERN U.P. EARLY THURSDAY. BUT THIS FAR OUT...ADJUSTMENTS TO PTYPE CERTAINLY LIKELY AS WE APPROACH THE EVENT. ALSO...WITH COMMENCEMENT OF STRONG WARM/MOISTURE ADVECTION IN THE LOWER LEVELS WEDNESDAY NIGHT AND SFC DEWPOINTS PUSHING UP TO AROUND 30F WED NIGHT AND FURTHER INTO THE MID/UPPER 30S ON THURSDAY (OVER THE SNOWPACK)...ADDED FOG MENTION TO FORECASTS BEGINNING WED NIGHT. ADAM && .APX...WATCHES/WARNINGS/ADVISORIES...SNOW ADVISORY...TODAY...MIZ015. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 645 AM EST MON DEC 27 2004 .UPDATE... A FORECAST UPDATE WILL ACCOMPANY THE AVIATION TAFS AS FOG AND LOW CLOUDS LOOK OVERWITH IN THE TRI CITIES AND THUMB. && .AVIATION... DRY AIR HAS SETTLED INTO THE TRI CITIES AND THUMB BUT LOW CLOUDS AND FOG REMAIN OVER THE AREA ALONG AND SOUTH OF I 69. THIS MOISTURE IS A COMBINATION OF THAT FROM LAKE HURON AND THE WEST END OF LAKE ERIE, AND IS TRAPPED UNDER THE LOW LEVEL INVERSION LAYER ASSOCIATED WITH THE SURFACE RIDGE JUST TO OUR WEST. BACKING FLOW FROM NORTH TO WEST ABOVE THE SURFACE LAYER WILL KEEP FLINT ON THE EDGE OF THE CLOUDS THROUGH THE MORNING AND WILL HELP THEM FILL IN AROUND DETROIT. AS THE SURFACE RIDGE MOVES TO OUR EAST, THERE IS SOME QUESTION AS TO HOW MUCH OF THE LOW CLOUDS WILL BE ABLE TO DISSIPATE. FOR NOW, WE'LL GIVE THEM A SHOT AT BREAKING UP BY EARLY AFTERNOON, BUT THERE IS A CHANCE THAT THEY COULD HOLD TOGETHER AND MOVE BACK NORTH, AND POSSIBLY REACH MBS LATE IN THE DAY. WARM ADVECTION WILL EVENTUALLY SCOUR OUT THE STRATUS TONIGHT AND LEAVE VFR CLOUDS AND VISIBILITY OVER THE REGION AFTER MIDNIGHT. SOUTH WINDS IN THE 10 TO 20 MPH RANGE WILL HAVE TEMPERATURES STEADY OR RISING. && .SHORT TERM... ISSUED AT 330 AM TODAY SATELLITE IMAGERY AND SURFACE ANALYSES SHOW HIGH PRESSURE BEGINNING TO HAVE AN IMPACT ON LAKE CLOUDS, SNOW SHOWERS, AND FOG PATTERN. EXPECT LOW LEVEL FLOW TO CONTINUE BACKING TOWARD THE NORTH AND TAKE THE LAKE EFFECT CLOUDS AND SNOW SHOWERS MORE TO OUR EAST WITH TIME THIS MORNING. NEARLY CALM SURFACE WINDS WILL NOT DO MUCH TO ADVECT THE DRY AIR INTO OUR REGION FROM NORTHERN LOWER, SO THERE IS A CHANCE THAT FOG WILL HOLD ON SOUTH OF THE TRI CITIES AND EXPAND INTO THE DETROIT AREA AS THE SURFACE RIDGE BUILDS OVERHEAD AROUND SUNRISE. DO NOT ANTICIPATE A HEADLINE FOR THE FOG GIVEN THE PACE OF VISIBILITY CHANGES SO FAR THIS MORNING, BUT WE'LL MONITOR. VARYING AMOUNTS OF FOG AND CLOUD COVER AFTER SUNRISE WILL COMBINE WITH STEADILY INCREASING HIGH CLOUDS DURING THE DAY TO MAKE THE TEMP FORECAST COMPLICATED. MID LEVEL WARM ADVECTION WILL CARRY IN THE CIRRUS AND ALTOSTRATUS, ESPECIALLY THIS AFTERNOON, AS THE SURFACE RIDGE SLOWLY MOVES EAST. THE CLOUDS, COMBINED WITH A SLOWLY DEVELOPING SOUTH WIND, WILL MAKE THE MID 20S OFFERED BY GUIDANCE THE HIGH END OF THE RANGE. EXPECT EVENING LOWS AND THEN RISING TEMPS OVERNIGHT TONIGHT. CLOUDS WILL THICKEN AND LOWER AND THE WIND WILL INCREASE INTO THE 10 TO 20 MPH RANGE TO HELP HOIST THE TEMPS TOWARD SUNRISE. MODEL SOUNDINGS AND CROSS SECTIONS SUGGEST THAT THETA-E ADVECTION WILL STRUGGLE TO PRODUCE ANY SNOW BEFORE SUNRISE. MID LEVEL MOISTURE PROFILES DO NOT SHOW VERY CONSISTENT SATURATION ABOVE THE BOUNDARY LAYER. EVEN THE USUALLY GENEROUS GFS IS LEAN ON QPF BY 12Z TUESDAY, SO A CHANCE OF FLURRIES WILL WORK GOOD FOR THE OVERNIGHT HOURS. && .LONG TERM... (TUESDAY-SUNDAY) TUESDAY... MODELS IN GENERAL AGREEMENT WITH BRINGING THE LARGE SURFACE HIGH TOWARD THE MIDDLE ATLANTIC COAST BY EVENING AS WEAKENING COLD FRONT APPROACHES THE WESTERN LAKES. AT 500MB, WE OBSERVE A FAIR AMOUNT OF CONFLUENCE AS WARM ADVECTION BEGINS TO UNFOLD UPSTREAM AND MAKE SOME INROADS. WITH THAT SAID, NOT SURE WHY THE GFS IS OVER-GENEROUS WITH ITS QPF ACROSS THE STATE ON TUESDAY AS IT IS THE ONLY MODEL (COMPARED TO THE ETA, CANADIAN, NGM, RUC13, UKMET) SUGGESTING ACCUMULATING SNOWFALL. FORECAST SOUNDINGS REVEAL A DISCONNECT IN THE MOISTURE PROFILES AND OVERALL LIFT IS LESS THAN IMPRESSIVE. IN ADDITION, WITH WARMING 850MB TEMPS (GOING ABOVE 0C) WE FEEL LAKE MICHIGAN CONTRIBUTION WILL BE MINIMAL. WE WILL RETAIN THE CHANCE OF LIGHT SNOW BUT DROP THE POPS TO 30%. THE FRONTAL BOUNDARY WILL BECOME DRAPED ACROSS LAKE HURON TUESDAY NIGHT AS IT BECOMES PARALLEL TO THE FLOW ALOFT FURTHER REDUCE ITS DEFINITION OVERNIGHT. STILL A BIT CONCERNED WITH SOME FOG DEVELOPING ACROSS THE TRI-CITIES AND THUMB AS LIGHT SURFACE FLOW, WEAK CONVERGENCE WITH AFOREMENTIONED FRONT, AND SOME WARM ADVECTION. 30AGL CPD/S SHOW THIS REGION DROPPING BELOW 30MBS PER THE ETA/GFS YET THEIR MOS VALUES SHOW NO HINT OF THIS (USUALLY, MOS DOES OFFER SOME GUIDANCE ON FOG POTENTIAL). THEREFORE, WE WILL HOLD OFF THE MENTION OF FOG BUT RETAIN THE CHANCE OF SOME FLURRIES WITH THE WARM ADVECTION AND RESULTING WEAK LIFT. WEDNESDAY... HEIGHTS RISE QUICKLY ACROSS THE GREAT LAKES THRU THE DAY BUT SOUNDINGS SHOW QUITE A BIT OF MOISTURE HANGING AROUND BELOW THE WARMING COLUMN ALOFT. THEREFORE, WE WILL SEE LIMITED SUNSHINE AND THIS WILL TAKE A TOLL ON THE SURFACE TEMPS. GUIDANCE NUMBERS STILL LOOK A TAD WARM AND WITH OUR CURRENT SNOWPACK AND PLENTY OF THAT UPSTREAM FROM US... WE WILL CLIMB ABOVE FREEZING BUT NOT BY MUCH. THE MAIN SHOW IN TERMS OF WARM ADVECTION ARRIVES WEDNESDAY NIGHT. IMPRESSIVE 850MB TEMP RECOVERY AS WE ARE EXPECTED TO CLIMB WELL INTO POSITIVE TERRITORY UPSTREAM AND WITH INCREASE LLJ IN EXCESS OF 50KTS, IT WILL NOT TAKE TOO LONG FOR US TO FEEL THE BENEFITS. HOWEVER, THIS WILL BRING ABOUT THE POTENTIAL FOR AN ADVECTION FOG REGIME AS SURFACE DEWPOINTS ARE EXPECTED TO CLIMB AOB FREEZING. THURSDAY... STRONG PIECE OF ENERGY EJECTS FROM THE PACIFIC UPPER LOW WITH STRONG CYCLOGENESIS LEE OF THE ROCKIES ACROSS THE PLAINS. THIS WILL ALLOW FOR A STRENGTHENING SOUTHERLY FLOW AND BRING ABOUT A CHANCE FOR RAIN (YES, RAIN). WITH 1000-850MB THICKNESSES CLIMBING WELL INTO THE 1300'S AND 850MB TEMPS PROGGED TO CLIMB TO BETWEEN +5/+8C...IT WILL BE ALL RAIN. QUESTION WILL BE WHERE THE CONCENTRATION OF RAINFALL WILL OCCUR. WHILE ISENTROPIC LIFT, AS ONE WOULD EXPECT, IS VERY IMPRESSIVE... THE LOWER CPD VALUES ARE ACROSS NORTHERN LOWER. STILL PLENTY OF TIME TO MAKE ADJUSTMENTS BUT AT THE MINIMUM WE WILL ADD THE CHANCE FOR RAIN. THE SYSTEM FILLS ACROSS THE GREAT LAKES BY WEEKS END WHICH SHOULD SLOW DOWN THE COLD AIR FILTERING SOUTH ONCE AGAIN BY THIS WEEKEND. .DTX WATCHES/WARNINGS/ADVISORIES... .MI...NONE. .LAKE HURON...NONE. .LAKE ST CLAIR...NONE. .MI WATERS OF LAKE ERIE...NONE. && $$ BT/BGM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1210 PM EST MON DEC 27 2004 .AVIATION... FOG AND STRATUS ACROSS SOUTH-CENTRAL LOWER MICHIGAN IS SLOWLY SHRINKING IN COVERAGE- FNT IS THE ONLY TAF SITE THAT MAY BE IMPACTED FOR A COUPLE OF HOURS EARLY THIS AFTERNOON AS THE EDGE OF THE CLOUD SHIELD MAY MOVE NORTHEAST AS THE CLOUD LAYER FLOW VEERS AROUND TO THE SOUTHWEST. OTHERWISE, ANTICIPATE THAT THE DISSIPATING TREND WILL CONTINUE THROUGH THE EARLY AFTERNOON HOURS. MID-HIGH CLOUDCOVER WILL RETURN TO SOUTHEAST MICHIGAN LATE THIS AFTERNOON AND EVENING. SOUTHERLY WINDS ARE EXPECTED TO SETTLE IN DURING THE EVENING HOURS IN THE WAKE OF THE SURFACE RIDGE. ANTICIPATE THAT THE PRESSURE GRADIENT WILL PREVENT THE SURFACE FLOW FROM DECOUPLING TONIGHT...AVERTING ANY FOG CHANCES OVERNIGHT. COULD BE A FEW STRAY LIGHT SNOW SHOWERS ACROSS THE NORTHERN SECTIONS TONIGHT, BUT NOT ENOUGH TO REDUCE CEILINGS OR VISIBILITIES. && .SHORT TERM... ISSUED AT 330 AM TODAY SATELLITE IMAGERY AND SURFACE ANALYSES SHOW HIGH PRESSURE BEGINNING TO HAVE AN IMPACT ON LAKE CLOUDS, SNOW SHOWERS, AND FOG PATTERN. EXPECT LOW LEVEL FLOW TO CONTINUE BACKING TOWARD THE NORTH AND TAKE THE LAKE EFFECT CLOUDS AND SNOW SHOWERS MORE TO OUR EAST WITH TIME THIS MORNING. NEARLY CALM SURFACE WINDS WILL NOT DO MUCH TO ADVECT THE DRY AIR INTO OUR REGION FROM NORTHERN LOWER, SO THERE IS A CHANCE THAT FOG WILL HOLD ON SOUTH OF THE TRI CITIES AND EXPAND INTO THE DETROIT AREA AS THE SURFACE RIDGE BUILDS OVERHEAD AROUND SUNRISE. DO NOT ANTICIPATE A HEADLINE FOR THE FOG GIVEN THE PACE OF VISIBILITY CHANGES SO FAR THIS MORNING, BUT WE'LL MONITOR. VARYING AMOUNTS OF FOG AND CLOUD COVER AFTER SUNRISE WILL COMBINE WITH STEADILY INCREASING HIGH CLOUDS DURING THE DAY TO MAKE THE TEMP FORECAST COMPLICATED. MID LEVEL WARM ADVECTION WILL CARRY IN THE CIRRUS AND ALTOSTRATUS, ESPECIALLY THIS AFTERNOON, AS THE SURFACE RIDGE SLOWLY MOVES EAST. THE CLOUDS, COMBINED WITH A SLOWLY DEVELOPING SOUTH WIND, WILL MAKE THE MID 20S OFFERED BY GUIDANCE THE HIGH END OF THE RANGE. EXPECT EVENING LOWS AND THEN RISING TEMPS OVERNIGHT TONIGHT. CLOUDS WILL THICKEN AND LOWER AND THE WIND WILL INCREASE INTO THE 10 TO 20 MPH RANGE TO HELP HOIST THE TEMPS TOWARD SUNRISE. MODEL SOUNDINGS AND CROSS SECTIONS SUGGEST THAT THETA-E ADVECTION WILL STRUGGLE TO PRODUCE ANY SNOW BEFORE SUNRISE. MID LEVEL MOISTURE PROFILES DO NOT SHOW VERY CONSISTENT SATURATION ABOVE THE BOUNDARY LAYER. EVEN THE USUALLY GENEROUS GFS IS LEAN ON QPF BY 12Z TUESDAY, SO A CHANCE OF FLURRIES WILL WORK GOOD FOR THE OVERNIGHT HOURS. && .LONG TERM... (TUESDAY-SUNDAY) TUESDAY... MODELS IN GENERAL AGREEMENT WITH BRINGING THE LARGE SURFACE HIGH TOWARD THE MIDDLE ATLANTIC COAST BY EVENING AS WEAKENING COLD FRONT APPROACHES THE WESTERN LAKES. AT 500MB, WE OBSERVE A FAIR AMOUNT OF CONFLUENCE AS WARM ADVECTION BEGINS TO UNFOLD UPSTREAM AND MAKE SOME INROADS. WITH THAT SAID, NOT SURE WHY THE GFS IS OVER-GENEROUS WITH ITS QPF ACROSS THE STATE ON TUESDAY AS IT IS THE ONLY MODEL (COMPARED TO THE ETA, CANADIAN, NGM, RUC13, UKMET) SUGGESTING ACCUMULATING SNOWFALL. FORECAST SOUNDINGS REVEAL A DISCONNECT IN THE MOISTURE PROFILES AND OVERALL LIFT IS LESS THAN IMPRESSIVE. IN ADDITION, WITH WARMING 850MB TEMPS (GOING ABOVE 0C) WE FEEL LAKE MICHIGAN CONTRIBUTION WILL BE MINIMAL. WE WILL RETAIN THE CHANCE OF LIGHT SNOW BUT DROP THE POPS TO 30%. THE FRONTAL BOUNDARY WILL BECOME DRAPED ACROSS LAKE HURON TUESDAY NIGHT AS IT BECOMES PARALLEL TO THE FLOW ALOFT FURTHER REDUCE ITS DEFINITION OVERNIGHT. STILL A BIT CONCERNED WITH SOME FOG DEVELOPING ACROSS THE TRI-CITIES AND THUMB AS LIGHT SURFACE FLOW, WEAK CONVERGENCE WITH AFOREMENTIONED FRONT, AND SOME WARM ADVECTION. 30AGL CPD/S SHOW THIS REGION DROPPING BELOW 30MBS PER THE ETA/GFS YET THEIR MOS VALUES SHOW NO HINT OF THIS (USUALLY, MOS DOES OFFER SOME GUIDANCE ON FOG POTENTIAL). THEREFORE, WE WILL HOLD OFF THE MENTION OF FOG BUT RETAIN THE CHANCE OF SOME FLURRIES WITH THE WARM ADVECTION AND RESULTING WEAK LIFT. WEDNESDAY... HEIGHTS RISE QUICKLY ACROSS THE GREAT LAKES THRU THE DAY BUT SOUNDINGS SHOW QUITE A BIT OF MOISTURE HANGING AROUND BELOW THE WARMING COLUMN ALOFT. THEREFORE, WE WILL SEE LIMITED SUNSHINE AND THIS WILL TAKE A TOLL ON THE SURFACE TEMPS. GUIDANCE NUMBERS STILL LOOK A TAD WARM AND WITH OUR CURRENT SNOWPACK AND PLENTY OF THAT UPSTREAM FROM US... WE WILL CLIMB ABOVE FREEZING BUT NOT BY MUCH. THE MAIN SHOW IN TERMS OF WARM ADVECTION ARRIVES WEDNESDAY NIGHT. IMPRESSIVE 850MB TEMP RECOVERY AS WE ARE EXPECTED TO CLIMB WELL INTO POSITIVE TERRITORY UPSTREAM AND WITH INCREASE LLJ IN EXCESS OF 50KTS, IT WILL NOT TAKE TOO LONG FOR US TO FEEL THE BENEFITS. HOWEVER, THIS WILL BRING ABOUT THE POTENTIAL FOR AN ADVECTION FOG REGIME AS SURFACE DEWPOINTS ARE EXPECTED TO CLIMB AOB FREEZING. THURSDAY... STRONG PIECE OF ENERGY EJECTS FROM THE PACIFIC UPPER LOW WITH STRONG CYCLOGENESIS LEE OF THE ROCKIES ACROSS THE PLAINS. THIS WILL ALLOW FOR A STRENGTHENING SOUTHERLY FLOW AND BRING ABOUT A CHANCE FOR RAIN (YES, RAIN). WITH 1000-850MB THICKNESSES CLIMBING WELL INTO THE 1300'S AND 850MB TEMPS PROGGED TO CLIMB TO BETWEEN +5/+8C...IT WILL BE ALL RAIN. QUESTION WILL BE WHERE THE CONCENTRATION OF RAINFALL WILL OCCUR. WHILE ISENTROPIC LIFT, AS ONE WOULD EXPECT, IS VERY IMPRESSIVE... THE LOWER CPD VALUES ARE ACROSS NORTHERN LOWER. STILL PLENTY OF TIME TO MAKE ADJUSTMENTS BUT AT THE MINIMUM WE WILL ADD THE CHANCE FOR RAIN. THE SYSTEM FILLS ACROSS THE GREAT LAKES BY WEEKS END WHICH SHOULD SLOW DOWN THE COLD AIR FILTERING SOUTH ONCE AGAIN BY THIS WEEKEND. .DTX WATCHES/WARNINGS/ADVISORIES... .MI...NONE. .LAKE HURON...NONE. .LAKE ST CLAIR...NONE. .MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION...MANN SHORT TERM...BT LONG TERM...BGM mi AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 258 PM CST TUE DEC 28 2004 .DISCUSSION... 20Z WATER VAPOR IMAGERY INDICATED STRONG H500 CUT OFF LOW ALONG CALIFORNIA COAST...WHILE H500 RIDGE REMAINED SITUATED OVER CENTRAL PLAINS. NORTHERN STREAM SHORTWAVE ALSO NOTED ON RUC TROPOPAUSE ANALYSIS NEARING MONTANA CANADIAN BORDER. MAIN CONCERNS WILL BE TEMPS THROUGH THE SHORT TERM AND ANY FOG CHANCES TONIGHT...FOLLOWED BY WX ASSOCIATED WITH STRONG SHORT WAVE ON WED-THU. FOR TONIGHT...MAIN QUESTION IS POTENTIAL FOR LOW CLOUDS AND FOG TONIGHT AND ITS IMPACTS ON TEMPS. 12Z/18Z MODELS DONT HAVE A GREAT HANDLE ON LARGE AREA OF LOW STRATUS/BR ACROSS WESTERN SD AND NORTH CENTRAL NE. SEE NO REASON WHY THIS AREA WONT TO ADVECT TO THE EAST OVERNIGHT AS BOUNDARY LAYER COOLS AND WEAK SFC TROUGH BEGINS TO SLIDE EAST. FOG WILL STAY IN THE 2-5SM RANGE THOUGH AS LOTS OF MID CLOUDS ARE GOING TO KEEP SFC COOLING AT BAY. WARMED UP TEMPS ACROSS THE WEST TO MATCH GOING SFC DEWPOINTS IN WESTERN SD AS THIS IS WILL PROBABLY THE MOST IT WILL BE ABLE TO COOL OVERNIGHT. TUESDAYS HIGHS WILL BE TRICKY AS ANY REMAINING STRATUS WILL INHIBIT WARMING AND WEAK COLD FRONT SHOULD SLIDE OVER THE AREA AS NORTHERN STREAM WAVE CRASHES INTO H500 RIDGE. BACKED OFF A FEW DEGREES OF GOING HIGHS AND WENT CLOSER TO COOLER FWC/MET GUIDANCE. BIG QUESTION CENTERS AROUND SYSTEM THAT WILL BEGIN TO ENTER THE CWA ON WED NIGHT. BIG DIFFERENCES WITH RESPECT TO THE ETA AND GFS. ETA CONTINUES ITS TREND OF BEING ABOUT 12 HOURS FASTER THAN THE GFS. END RESULT IS WARMING NEVER GETS TO CWA AND MAIN PRECIP TYPE WOULD BE FZRA. HOWEVER ECMWF AND CANADIAN BOTH FAVOR GFS WARMER/SLOWER SOLUTION AND WILL CONTINUE ALONG LINES OF 12Z GFS WITH ALL RAIN OVERNIGHT WED. ALL MODELS POINT TO RATHER UNSTABLE MID LEVELS WHEN THIS SYSTEM KICKS OUT AND WOULDNT BE TOTALLY SURPRISED TO SEE AN ISOLATED LIGHTNING STRIKE WHEN IT MOVES OVER THE AREA...BUT WILL WAIT FOR A FEW MORE RUNS BEFORE ADDING TO FORECAST. ALSO DEGREE OF INSTABILITY AND STRONG TEMP GRADIENT LEADS ME TO THINK THAT THIS LOW MAY INTENSIFY/SLOW MORE THAN EVEN THE GFS SUGGESTS...SO FOR TIMING OF PRECIP WENT ABOUT 6 HOURS SLOWER THAN GFS WOULD SUGGEST. TEMPTED TO BUMP UP POPS TO LIKELY...BUT WITH AN EXPECTED STRONG DRY SLOT POSSIBLY CUTTING OFF PRECIP EARLY...WILL HOLD OFF FOR NOW. IN THE EXTENDED...COMPLICATED EXTENDED FORECAST CONTINUES THROUGH THE WEEKEND AS ALL MODELS POINT TO TROUGH DIGGING OVER THE ROCKIES AND ARCTIC BOUNDARY LINGERING OVER THE CENTRAL PLAINS. FIRST CONCERN IS EXITING LOW PRESSURE SYSTEM. LATEST MODELS COMING IN A BIT SLOWER WITH THIS WAVE AND HOLD ON TO THE CHANCE FOR PRECIP A BIT LONGER THROUGH THUR EVENING. ALTHOUGH MUCH OF THE DYNAMIC FORCING WILL BE EAST OF CWA BY THEN...WRAP AROUND STREAMLINES DONT TURN FULLY TO DOWNGLIDE UNTIL EARLY FRI MORNING. ALSO DGEX/GFS/ECMWF SHOWING SOME COLD AIR BEING ENTRAINED INTO THE BACKSIDE OF THE SYSTEM AND CHANGED PRECIP TYPE FROM RA TO RA OR SN ON THE BACKSIDE OF SYSTEM. MODELS REALLY DIVERGE WITH HANDLING OF UPCOMING SHORT WAVES THROUGH THE REST OF THE EXTENDED. 00Z GFS SHOWING DECENT CONTINUITY WITH YESTERDAYS RUN THROUGH SAT SO WILL KEEP POPS IN FOR SNOW ON SAT/SUN...WITH 12Z GFS BEGINNING TO TREND TOWARDS ECMWF'S STRONGER INVERTED TROUGH SOLUTION. GFS/DGEX INDICATING A MORE SIGNIFICANT SYSTEM EFFECTING CWA ON MON...WITH ECMWF MUCH SLOWER WITH THIS WAVE. DUE TO THE EXPECTED STRENGTH OF THIS WAVE...PREFER SLOWER SOLUTION BUT WILL ADD SMALL POPS TO LATE MONDAY. DESPITE THE STRENGTH OF THIS SYSTEM...DONT THINK HIGHER POPS THAN 30 ARE JUSTIFIED JUST YET AS LARGE UNCERTAINTY WITH RESPECT TO TIMING AND PATH STILL EXISTS. FOR TEMPS...CONTINUED COOLING TREND IN THE EXTENDED WITH ARCTIC BOUNDARY NEARING CWA. DID NOT GO AS COLD AS MEX ON FRI-SAT AS THINK GFS IS BEING TO AGGRESSIVE WITH COLD AIR UNDER H500 RIDGE. FOR SUN-MON LARGE RANGES (NEARING 30 DEGREES)( BEGIN TO SHOW UP IN ENS GUIDANCE...SO HEDGED TEMPS CLOSER TO MEAN NUMBERS. && .AVIATION... MVFR CIGS STRATUS AREA HAS REMAINED STNRY TODAY FM N CNTRL NEB...NWD TO CNTRL SD AND THEN EWD TOWARD CNTRL MN. THE LEADING EDGE OF IT IS STILL ROUGHLY IN THE JAMES VALLEY...THEN ARCHING EWD TO NR KBKX AND KMML. IT IS PROGGED THAT THIS AREA OF LOWER CIGS WL GRADUALLY LIFT NWD WITH THE SLY FLOW OFF THE SFC TONIGHT. INDEED...SOME HOLES HAS DEVELOPED IN IT ALREADY IN THE FSD FA AND THIS TREND MAY CONT. WITH THE DEAD AIR TNGT...BE ALERT FOR SOME POSSIBLE IFR VSBYS BY AROUND SUNRISE TUE MORNING. OTHERWISE...CURRENT TAFS AND TWEBS LOOK GOOD AND HAVE ANTICIPATED TRENDS IN THEM. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE MN...NONE IA...NONE NE...NONE. && JRM/MJF sd