AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 820 PM EST TUE JAN 4 2005 .SYNOPSIS...MID/UPPER AIR ANALYSIS SHOWS CLOSED LOW INVOF SRN NV. DOWNSTREAM RIDGE CENTERED OVER THE GULF OF MEXICO CONTINUES TO DEFLECT MOST OF THE SHORT WAVE ENERGY AND MOISTURE TO THE N AND W OF THE AREA. SURFACE ANALYSIS PLACES THE E-W RIDGE AXIS OVER SRN GA/NRN FL. CONSEQUENTLY, WINDS HAVE BECOME CALM AT MOST SITES. DEW POINTS ARE A BIT WARMER THIS EVENING COMPARED TO PREVIOUS 24 HOURS. THE 00Z TLH RAOB INDICATES SOME WARMING OF THE 600-800 MB LAYER, WITH PRECIP WATER LOWERING FROM AN INCH TO 0.81 INCH. BOUNDARY LAYER WINDS WERE LIGHT FROM THE S. BANDS OF HIGH CLOUDS SPILLING OVER THE UPPER RIDGE ARE CREATING GENERALLY P/CLOUDY SKIES. THE VSBY AT VLD RECENTLY DROPPED TO 3 MILES. && .PUBLIC...LATEST ETA CONDENSATION PRESSURE DEFICIT PROGS DEPICT BETTER DENSE FOG POTENTIAL OVER S/CNTRL GA AND ERN FL BIG BEND OVERNIGHT, SIMILAR TO WHAT TRANSPIRED EARLY THIS MORNING. AN ADVISORY MAY BE REQUIRED DURING THE NEXT SHIFT SHOULD CONDITIONS WARRANT. 00Z TEMPS IN LINE W/ GUIDANCE, HOWEVER DEW POINTS ARE A LITTLE COOLER. NO CHANGES TO THE ZONE FCST. && .MARINE...BUOYS REPORTING ELY WINDS 5-10 KTS AND SEAS 3 FT OR LESS. BOTH ETA AND RUC SHOW WINDS VEERING TO THE SE TOWARD MORNING AS THE SURFACE RIDGE SHIFTS A BIT FURTHER TO THE S. THE ONLY CHANGE WILL BE TO ADJUST WINDS. REMAINDER OF FCST ON TRACK. && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. && $$ MAJ fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1045 PM EST TUE JAN 4 2005 .UPDATE... AM NOT PLANNING ON ANY SIGNIFICANT CHANGES TO THE FORECAST OR CURRENT HEADLINES THIS EVENING AS SNOW IS BREAKING OUT UPSTREAM AND OVERHEAD. 4-5 G/KG SPECIFIC HUMIDITIES SEEN ADVECTING NORTH ON 295K ISENTROPIC SURFACE. ISENTROPIC LIFT NOT PARTICULARLY STRONG OVERNIGHT... BUT MAIN FORCING MECHANISM WILL BE STRONG UPPER LEVEL DIVERGENCE BETWEEN 06Z AND 12Z. SW MI WILL BE SQUARELY IN AN IMPRESSIVE LOOKING COUPLED JET STRUCTURE. (150-190KT H2 JET STRETCHING FROM LAKE SUPERIOR TO MAINE... AND ANOTHER 150 KNOT JET POINTED NE FROM THE SRN PLAINS.) THIS HELPS INDUCE A HEALTHY BAND OF FRONTOGENETICAL FORCING OVERNIGHT. EXPECT SNOW TO DEVELOP/INCREASE RAPIDLY THROUGH 1 AM AND POSSIBLY BE HEAVY AT TIMES OVERNIGHT ALONG AND SOUTH OF I96. HEAVIEST ACCUMS EXPECTED ALONG THE I94 CORRIDOR WHERE BEST FORCING AND MOISTURE WILL BE PRESENT. THEN LOOK FOR A TEMPORARY DECREASE IN SNOW FOR A TIME WEDNESDAY MORNING AS AFOREMENTIONED JET DYNAMICS PULL AWAY. UPPER SYSTEM COMES OUT WEDNESDAY NIGHT AND MOVES THROUGH THURSDAY MORNING. LATEST ETA HAS A HALF INCH OR MORE OF QPF WITH THAT FEATURE... MAINLY ALONG/NORTH OF I96. SO... A PROLONGED EVENT FOR SW MI WITH POSSIBLY A FOOT OR MORE OF SNOW IN SOME SPOTS BY 18Z THURSDAY. LOOKS LIKE I96 CORRIDOR GETS IN ON BOTH THE ISENTROPIC EVENT TONIGHT/WED AND THE UPPER LOW WED NGT/THUR... SO HIGHEST STORM TOTALS POSSIBLY MKG-GRR-LAN. NOT IMPOSSIBLE THAT SOME SLEET COULD MIX IN AS PCPN DEVELOPS OVERNIGHT... BUT LAPS/RUC SOUNDINGS LOOK TO SUPPORT ALL SNOW AS EVENT UNFOLDS. && .GRR WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING LATE TONIGHT THROUGH WED NIGHT SOUTH OF A MUSKEGON TO LANSING LINE. WINTER STORM WATCH WED NIGHT AND THURSDAY MORNING NORTH OF A MUSKEGON TO LANSING LINE. && $$ MEADE mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 857 PM EST TUE JAN 4 2005 .UPDATE... CURRENT FORECAST PACKAGE IS GENERALLY DOING VERY WELL. BASED ON LATEST RUC AND CURRENT RADAR TRENDS OF PRECIPITATION APPROACHING FROM THE SOUTH AND WEST...WILL JUST SLIDE BACK ONSET OF SNOW MENTION A COUPLE OF HOURS...TO ABOUT 05Z. OTHERWISE NO CHANGES. && .AVIATION...ISSUED 656 PM EST TUESDAY AS IN PREVIOUS COUPLE OF DAYS...ESSENTIALLY GOING WITH MVFR CEILINGS EXCEPT QUITE A BIT OF IFR CEILINGS MAINLY LATE TONIGHT AND ALSO WEDNESDAY ESPECIALLY IN THE SOUTH. THE OTHER EXCEPTION WILL BE OCCASIONAL CEILINGS FLARING INTO VFR CATEGORY AS PER CURRENT TRENDS THIS EVENING...BUT SHOULD SETTLE BACK DOWN BELOW VFR THROUGHOUT BY LATE EVENING AS LOW LEVEL MOISTURE AGAIN INCREASES. AS FOR VISIBILITY...PRIMARILY VFR UNTIL SNOW BEGINS. VISIBILITIES DETERIORATING TO IFR AROUND 07Z IN SNOW FOR DTW/DET AND THEN 3 MILES WEDNESDAY MORNING BEFORE DOWN TO 1 MILE IN HEAVIER SNOW BY 18Z. FOR FNT AND MBS...ESPECIALLY MBS...MUCH MORE OPTIMISTIC VISIBILITIES GIVEN THESE SITES BEING MORE ON THE FRINGE OF EXPECTED SNOW SHIELD. && .SHORT TERM...TONIGHT AND WEDNESDAY...ISSUED 430 PM EST TUESDAY LOW PRESSURE SYSTEM WILL DEEPEN OVER SOUTHERN MISSOURI AND WILL BEGIN TO TRACK TOWARDS CENTRAL OHIO AS A STRONG CLOSED LOW OVER SOUTHERN CALIFORNIA PROGRESSES EASTWARD. THIS LOW PRESSURE SYSTEM WILL IMPACT SOUTHERN MICHIGAN OVERNIGHT WITH AN INITIAL BURST OF SNOW...WITH MORE SNOW EXPECTED ACROSS THE AREA WEDNESDAY AFTERNOON THROUGH MIDDAY ON THURSDAY. WINTER STORM WARNING WILL BE OUT SOON FOR COUNTIES ALONG AND SOUTH OF I-94 WITH WATCHES FOR TOMORROW EXTENDING NORTH TO I-69 PLUS SANILAC COUNTY. LOW LEVEL JET WILL MOVE UP THE OHIO RIVER VALLEY OVERNIGHT... TRANSPORTING GOOD MOISTURE TO ITS NORTH AND TIGHTENING THE BAROCLINIC ZONE FROM ILLINOIS TO OHIO. THE FORECAST QUESTION FOR TONIGHT IS IF ENOUGH MOISTURE WILL BE IN PLACE FOR A FEW INCHES OF SNOW OVER OUR SOUTHERN COUNTIES BY MORNING. MODELS SHOWING GOOD MID LEVEL FRONTOGENETICAL FORCING ALONG AND SOUTH OF THE MICHIGAN BORDER TONIGHT WITH THE BEST OMEGA PASSING OVER NORTHERN INDIANA AND OHIO BY 12Z. ETA12 INDICATING OVER .60 QPF BY 18Z WEDNESDAY IN LENAWEE AND MONROE COUNTIES SO WILL GO AHEAD WITH THE WINTER STORM WARNING FOR 4 SOUTHERN MOST COUNTIES IN CWA STARTING TONIGHT. LIMITING FACTOR MAY BE MOISTURE WITH DRY NORTHEASTERLY FLOW SNEAKING IN FROM THE NORTH. THIS SHOULD PROVIDE A SHARP BOUNDARY PREVENTING THE SNOWFALL FROM SPREADING FURTHER NORTH OVERNIGHT. HAVE UNDERCUT ETA NUMBERS A LITTLE WITH CONCERN ABOUT INTRUSION OF DRY AIR AND SOME QUESTION ABOUT MID LEVEL FGEN WEAKENING. OTHERWISE EXPECT SOME SNOW TO BE ON THE GROUND BY SUNRISE ON WEDNESDAY...MAINLY SOUTH OF I-94. MODELS HAVE SPED UP THE TIME FRAME ON THE PERIOD OF BEST LIFT INDICATING THAT MOST OF THE SNOW WILL FALL BETWEEN MIDNIGHT AND DAWN...WITH SOME SNOW CONTINUING ON INTO THE MORNING COMMUTE. SNOW WILL TAPER OFF BY MID MORNING BUT WILL NOT BE FINISHED FOR THE DAY. THIS INITIAL PERIOD OF SNOW PRECEDES A PERIOD OF HEAVIER SNOW AREA WIDE EXPECTED WEDNESDAY AFTERNOON AND NIGHT. AS THE SURFACE LOW APPROACHES...GOOD DYNAMICS WILL SUPPORT SIGNIFICANT SNOWFALL. WE REMAIN UNDER GOOD JET COUPLING WITH UPPER LEVEL DIVERGENCE OVERHEAD AS THE 500MB TROUGH APPROACHES. && .LONG TERM...WEDNESDAY EVENING THROUGH FRIDAY...ISSUED 430 PM EST TUESDAY THE WINTER STORM WILL BE IN FULL SWING OVER SE MICHIGAN HEADING INTO WEDNESDAY NIGHT. IT IS AT THIS POINT THAT WE TRANSITION FROM ALL SNOW OVER THE ENTIRE AREA TO HEAVY SNOW OVER CENTRAL SECTIONS AND SIGNIFICANT MIXED PRECIP NEAR THE OHIO BORDER. THERE IS GOOD MODEL AGREEMENT ON A TRACK OF THE SURFACE LOW THROUGH SOUTHERN INDIANA AND SOUTHERN OHIO, GENERALLY ALONG OR JUST SOUTH OF A LINE FROM IND TO CLE. THERE IS ALSO GOOD AGREEMENT ON A FAIRLY BROAD INVERTED TROF ON THE NW FLANK OF THE SURFACE LOW, WHICH IS A RESULT OF THE NEGATIVE/WESTWARD TILT IN THE SYSTEM THROUGH THE LOW AND MID LEVELS. THIS ASPECT OF THE LOW, ALONG WITH A CLOSED MID LEVEL CIRCULATION, WILL MAKE HEAVY SNOW AND MIXED PRECIP A PROBLEM AROUND DETROIT TO THE OHIO BORDER AND ALL HEAVY SNOW MORE PROBABLE THROUGH CENTRAL SECTIONS OF SE MICHIGAN. SNOWFALL ACCUMULATION, AND THE IMPACT ON IT BY MIXED PRECIP, WILL CONTINUE TO BE UNDER CONSTRUCTION BUT SOME PRECISION IS BECOMING POSSIBLE WITH FAIRLY CONSISTENT MODEL SOLUTIONS. MODEL FORECAST SOUNDINGS AND CROSS SECTIONS FROM THE ETA SHOW AN INTRUSION OF WARM AIR INTO SOUTH SECTIONS OF OUR AREA DURING THE EVENING. THIS IS SHOWN IN CROSS SECTIONS OF WET BULB TEMPERATURE AND THICKNESS FORECASTS FOR THE 850 TO 700 MB LAYER, WHILE 1000-850 MB THICKNESS SAYS SNOW THROUGHOUT THE EVENT. THE GFS IS COLDER AND SHOWS A CLEAR COLDER RESPONSE IN THE MID LEVEL THICKNESS FIELD, SUGGESTING ALL SNOW, AS HEAVIER PRECIP RATES MOVE INTO THE AREA. ON THE OTHER HAND, THE NEGATIVE/WESTWARD TILT TO THE SYSTEM IN ALL OF THE MODELS SUGGESTS THE POTENTIAL FOR AT LEAST SOME WARM AIR TO WORK THROUGH THE LOW LEVELS, ESPECIALLY LATER IN THE EVENING AS PRECIP RATES SLOW DOWN. EXPECT BOTH PRECIP RATE AND THE VERTICAL STRUCTURE OF THE SYSTEM TO PLAY A ROLE AND WILL MAINTAIN MIXED PRECIP AROUND AND SOUTH OF DETROIT, PROBABLY MORE SLEET THAN FREEZING RAIN AND ENOUGH TO CUT INTO SNOW ACCUMULATION, MUCH LIKE IN OUR GOING FORECAST GRIDS. THE SWATH OF HEAVIEST SNOWFALL WILL SET UP ALONG THE AXIS OF THE TROWAL AROUND 700 MB. THE 12Z MODELS SHOW THIS SETTING UP ROUGHLY THROUGH THE I 69 CORRIDOR AS THE SYSTEM OCCLUDES TOWARD MIDNIGHT WEDNESDAY NIGHT. OCCLUSION DYNAMIC FORCING AND LOW STATIC STABILITY WILL LIKELY GENERATE A STRONG VERTICAL MOTION RESPONSE IN THIS AREA DURING THE LATE EVENING AND OVERNIGHT HOURS. SPECIFIC HUMIDITY AROUND 3 G/KG FOR ABOUT AN 18 HR PERIOD MATCHES UP PRETTY WELL WITH MODEL QPF. TOTAL SNOW ACCUMS IN THE 6 TO 10 INCH RANGE ARE ON TARGET IN THE WATCH AREA, WITH LOCAL ACCUMS NEAR 12 INCHES POSSIBLE. THE DRY SLOT WILL CUT OFF THE SNOW QUICKLY AROUND 12Z THURSDAY. THE DRY AIR IN THE MID LEVELS, COMBINED WITH SURFACE CONVERGENCE IN THE LOW LEVEL CYCLONIC FLOW, WILL BRING SOME FREEZING DRIZZLE INTO THE PICTURE THURSDAY MORNING. THE TRI CITIES AND THUMB WILL CONTINUE WITH GENERALLY LIGHT SNOW FORCED BY THE MID LEVEL DEFORMATION ZONE, BUT WITH SOME ACCUMULATION POTENTIAL. GENEROUS QPF IN THE MODELS IS THE RESULT OF A WELL-ORGANIZED MOIST CONVEYOR FROM THE LOW AND MID LEVEL OCCLUSION. THURSDAY ACCUMS IN THE 1 TO 3 INCH RANGE AROUND THE TRI CITIES AND THUMB WILL KEEP THAT AREA JUST UNDER WARNING CRITERIA SNOWFALL FOR THE WEDNESDAY NIGHT AND THURSDAY 24 HOUR PERIOD, BUT WE'LL HAVE TO KEEP AN EYE ON THAT AND ANY LAKE CONTRIBUTIONS THAT COULD BOOST THE TOTALS. THIS SYSTEM WILL LEAVE BEHIND A DRY AND FLAT PATTERN ON FRIDAY AS HEIGHT FALLS RELOAD THE BLOCKING UPPER AIR PATTERN OVER THE EASTERN PACIFIC AND WEST COAST. BROAD SW FLOW ALOFT AND HIGH PRESSURE ALONG THE EAST COAST WILL KEEP TEMPERATURES NEAR 30 FOR HIGHS WITH LOWS AROUND 20. TEMPERATURE GUIDANCE LOOKS PRETTY GOOD FOR THIS TIME PERIOD. && .LONG TERM...SATURDAY THROUGH TUESDAY...ISSUED 430 PM EST TUESDAY THE BLOCKING PATTERN IN THE PACIFIC WILL CONTINUE INTO THE EARLY NEXT WEEK. THIS WILL RESULT IN PERSISTENT TROUGHING ACROSS THE WEST COAST AND BROAD SOUTHWEST FLOW ACROSS THE CENTRAL AND EASTERN US... MAINTAINING RELATIVELY MILD WEATHER ACROSS SE MICHIGAN. THE LATEST TRENDS IN THE MODELS HAVE BEEN A BIT STRONGER WITH HIGH PRESSURE OVER SOUTHERN CANADA... WHICH SLOWS THE WARMING A LITTLE BIT. WILL BACK OFF ON HIGHS ON SATURDAY DUE TO THIS TREND... BUT CONTINUE WITH HIGHS NEAR 40 SUN THROUGH TUE. THE GFS/DGEX/WRFXX HAVE BEEN CONSISTENT IN BRINGING A WEAK SHORT WAVE THROUGH THE REGION SAT/SAT NIGHT... SO WILL CONTINUE WITH A CHANCE OF LIGHT RAIN/SNOW. THE GFS HAS BEEN FAIRLY CONSISTENT SHOWING A POLAR VORTEX DROPPING INTO CENTRAL CANADA BY MID WEEK... THEN PHASING WITH THE SOUTHERN STREAM TROUGH OFF THE WEST COAST... LEADING TO A FULL LATITUDE TROUGH OVER THE CENTRAL US BY THE END OF THE WEEK. THIS IDEA WOULD BRING ANOTHER STRONG STORM SYSTEM IN THE CENTRAL US TUES INTO WED. AT THIS POINT... SE MICHIGAN APPEARS TO BE ON THE WARM SIDE OF THIS SYSTEM. && .DTX WATCHES/WARNINGS/ADVISORIES... .MI... WINTER STORM WARNING...MIZ075-076-082-083...EARLY WEDNESDAY THROUGH THURSDAY MORNING. WINTER STORM WATCH...MIZ055-060>063-068>070...WEDNESDAY AFTERNOON THROUGH THURSDAY MORNING. .LAKE HURON...SMALL CRAFT ADVISORY...SAGINAW BAY AND THE NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON...WEDNESDAY THROUGH WEDNESDAY NIGHT. .LAKE ST CLAIR...SMALL CRAFT ADVISORY...WEDNESDAY AND WEDNESDAY NIGHT. .MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY...WEDNESDAY AND WEDNESDAY NIGHT. DWD/SC/BT/KEK mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 345 PM EST TUE JAN 4 2005 .SHORT TERM... HAVE DECIDED TO GO WITH A WINTER WARNING BEGINNING LATE TONIGHT ALONG AND SOUTH OF A MUSKEGON TO LANSING LINE. I KEPT THE WINTER STORM WATCH GOING FURTHER NORTH FOR WED NIGHT AND INTO THU AM. THERE ARE A COUPLE OF REASONS THAT I UPGRADED THE SOUTHERN COUNTIES TO WARNING. FIRST IS THE LARGE AREA OF HEAVIER PRECIPITATION DEVELOPING UPSTREAM ACROSS KS NE AND ND. THIS AREA OF PRECIPITATION IS DEVELOPING UNDER A IMPRESSIVE COUPLED JET SEEN ON THE RUC MODEL AT 300 MB. STRONG DIVERGENCE WAS NOTED AT THIS LEVEL. THIS COUPLED JET PULLS INTO WI BY 06Z AND EVENTUALLY PORTIONS OF SOUTHWEST LOWER MICHIGAN AFTER MIDNIGHT. STRONG FRONTOGENETICAL FORCING WAS NOTED IN THE MID LEVELS AND PLENTIFUL MOISTURE FROM THE GULF APPROACHING AN INCH ARRIVES NEAR SOUTHERN LAKE MICHIGAN AROUND 06Z. LOOKING AT FORECAST SOUNDINGS ALL SNOW IS EXPECTED...EVEN SOUTHERN COUNTIES. AS FOR ACCUMULATIONS... AM THINKING AMOUNTS RANGING FROM NEAR 2 INCHES NORTHERN KENT COUNTY RANGING TO NEAR 5 ALONG INTERSTATE 94 BY DAYBREAK. WITH DEEP MOISTURE AND ONGOING MID LEVEL FRONTOGENETICAL LIFT IN THE MID LEVELS SHOULD KEEP THE SNOW GOING IN THE WARNING AREA FOR THE MORNING COMMUTE...ESPECIALLY SOUTH OF INTERSTATE 96. THE MODELS GFS AND ETA DO SUGGEST A LULL IS POSSIBLE IN THE STORM ACROSS THE WARNING AREA DURING THE DAY ON WEDNESDAY. ISENTROPICALLY THIS DOES NOT SEEM TO BE THE CASE WITH LOW CPD'S IN THE MID LEVELS THROUGH THE DAY ON WEDNESDAY. MOISTURE IS IMPRESSIVE AT THIS LEVEL WITH SPECIFIC HUMIDITY LEVELS AROUND 4 GRAMS AT 18Z WED. STILL FOR THE WARNING AREA I DID MENTION OCCASIONAL SNOW IN THE EVENT THAT WED DID SEE A BREAK. ANOTHER 2 TO 3 INCHES APPEARS LIKELY FOR THE WARNING AREA DURING THE DAY ON WED. THE LATEST FORECAST SOUNDINGS KEEP IT SNOW EVEN FOR THE SOUTHERN COUNTIES THROUGH WED. AN DECENT TROWAL(TROUGH OF WARM AIR ALOFT) SETS UP ACROSS THE ENTIRE REGION FOR WED NIGH AND THIS IS WHEN THE HEAVIEST SNOWS SHOULD OCCUR NORTH OF INTERSTATE 94. THIS HEAVIER SNOW MAY LINGER ACROSS THE NORTHERN COUNTIES INTO THURSDAY MORNING. STORM TOTALS OF 8 TO 12 INCHES ARE EXPECTED ACROSS THE WARNING AREA THROUGH WEDNESDAY NIGHT. AMOUNTS COULD GO HIGHER IF THE SNOW TURNS CONVECTIVE. IS DID NOTICE SOME THETA E DECREASING WITH HEIGHT WED NIGHT. NORTHEAST WINDS OF 15 TO 25 MPH SHOULD BLOW THE SNOW AROUND LEADING TO DRIFTING AS WELL ESPECIALLY WEDNESDAY NIGHT. .LONG TERM... THE EVOLUTION TOWARD A HIGH AMPLITUDE LONG WAVE WILL BE UNDERWAY AS THE EXTENDED PERIOD COMMENCES. WE'RE GOING TO SEE SEVERAL SHORT WAVES MOVE TOWARD THE CWA AS SOUTHWEST FLOW ALOFT DEVELOPS AND SHORT WAVES EJECT OUT OF THE BASE OF THE WESTERN US TROUGH. FRIDAY NIGHT LOOKS DRY. A MINOR WAVE IS PROGGED TO MOVE THROUGH SATURDAY AFTERNOON AND NIGHT. THE ASSOCIATED SFC LOW THAT DEVELOPS IN THE NORTHERN PLAINS WILL PUSH A WARM FRONT NORTH THROUGH THE CWA SATURDAY NIGHT. THERMAL PROFILES SUGGEST A MIX OF RAIN AND SNOW. AFTER A DRY SUNDAY AND SUNDAY NIGHT ANOTHER LOW IS PROGGED TO MOVE FROM THE PLAINS TOWARD THE CWA. DGEX SHOWS A STRONG PUSH OF WARM AIR AHEAD OF THE LOW. WITH GO WITH RAIN ON TUESDAY AS 850 MB TEMPS RISE TO +6C. && .GRR WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING LATE TONIGHT THROUGH WED NIGHT SOUTH OF A MUSKEGON TO LANSING LINE. WINTER STORM WATCH WED NIGHT AND THURSDAY MORNING NORTH OF A MUSKEGON TO LANSING LINE. && $$ MJS 93 mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 1039 AM MST TUE JAN 4 2005 .UPDATE...SATELLITE...RUC ANALYSIS AND RADAR TRENDS INDICATE ENHANCEMENT ACROSS CENTRAL AREAS AS FRONT LEFT INFLUENCE OF A SIGNIFICANT JET TRANSLATES IN. IT APPEARS IT IS BECOMING MORE CYCLONIC/SLIGHT NEGATIVE TILTING...DECIDED TO REFOCUS HIGHEST POP AREAS ACROSS CENTRAL AREAS. THIS INCLUDES THE ABQ METRO AREA. ALSO ADJUSTED HOURLY TEMPERATURES EVENTUALLY FOR THE INTERNET TO REFLECT STEADY THEN FALLING TEMPS IN THE WEST AS SNOW LEVELS DROP. SNOW LEVELS QUITE VARIED ACROSS CWFA AND HAVE INDICATED THAT WITH NEW ZONES. SIGNIFICANT JET AND VORT DYNAMICS EXPECTED ACROSS THE NORTHEAST TONIGHT. QUESTION STILL REMAINS ON THE PUSH OF THE POLAR FRONT. HAVENT DECIDED ON WHAT TO DO UP THERE YET AS FAR AS HIGHLIGHTS BUT FIGURE UNION COUNTY WILL GET THE LIQUID PRECIP TURNING OVER TO FROZEN PRECIP BETWEEN 7 TO 8 PM PER LATEST MODEL 850 T PROG CHARTS AND SOUNDINGS. RIGHT NOW THINKING ADVISORY TYPE SNOW AMOUNTS BUT IF FEEL LATER TODAY THAT THERE WILL BE AN INITIAL SIGNIFICANT ICING EVENT MAY GO WARNING. LITTLE LEARY ABOUT THE SACRAMENTO MOUNTAINS AND WATCH CURRENTLY THERE FOR TONIGHT. FEEL MAIN DYNAMICS WITH HIGH SNOW LEVELS LATER TODAY THEN LESSENING TONIGHT. ALSO EXPANDED THUNDER ACROSS SOUTHERN AND CENTRAL AREAS FOR THIS AFTERNOON AS JET PUNCHES IN. WACHTER .PREV DISCUSSION...LOTS TO CONSIDER IN THIS PACKAGE. DECIDED TO KEEP HIGHLIGHTS...WINTER STORM WARNINGS AND WATCHES...AS IS FOR NOW... BUT STILL HAVE SOME CONCERN ABOUT DRY SLOTTING WHICH MAY BE A BIT AHEAD OF SCHEDULE INTO SW AND W CENTRAL NM. DO EXPECT THOUGH THAT SHOWERY PCPN WOULD FILL IN IF THERE IS MUCH SUNSHINE AT ALL THAT BREAKS OUT. OF COURSE SNOW LEVELS WOULD RISE A BIT HIGHER THAN EXPECTED IF HEATING KICKS IN A BIT MORE THAN FCST. WILL MODIFY WSW TO BUMP TO 8500 OR MAYBE EVEN 9000 THE LEVEL ABOVE WHICH THE GREATEST SNOW ACCUMULATIONS ARE MOST LIKELY AND MAY ALSO DECREASE TOTAL OVERALL ACCUMULATIONS SLIGHTLY. FOR SANDIAS S TO SACRAMENTOS DAY SHIFT MAY WANT TO CONSIDER LATEST MODEL AND SATELLITE/RADAR TRENDS AS TO HOW LONG INTO TONIGHT TO HANG ONTO HIGHLIGHTS. GIVEN INCREASED DRY SLOTTING HAVE A LITTLE UNCERTAINTY ABOUT WATCH ACROSS FAR NE...AS TO WHETHER THERE WILL BE ENOUGH PCPN TONIGHT INTO WED AM TO REALLY JUSTIFY A WARNING. BUT WILL KEEP IT FOR NOW SINCE DO NOT NEED MUCH FREEZING RAIN TO CREATE LIFE-THREATENING TRAVEL CONDITIONS...AND THE SHALLOW COLD AIR SHOULD BE COLD ENOUGH TO KEEP ROAD SURFACES BELOW FREEZING. THIS MESS GETS OUTTA HERE FINALLY LATE TONIGHT INTO WED AND WE GET A BIT OF A BREAK INTO AT LEAST EARLY FRIDAY. RELATIVELY FEW AND MINOR CHANGES FOR LATE WEEK INTO EARLY NEXT WEEK GRIDS. && .ABQ WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING THROUGH TUESDAY NIGHT NMZ002...004...008...010 AND 014. WINTER STORM WATCH TONIGHT NMZ017. WINTER STORM WATCH TONIGHT THROUGH WEDNESDAY MORNING NMZ005... 006...007. && $$ 43/50 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 950 PM CST TUE JAN 4 2005 .DISCUSSION... LATEST SFC/RADAR TRENDS AND MODEL DATA INDICATE MAJOR ICE STORM UNFOLDING ACROSS NW OK AND LIKELY TO SPREAD INTO NCENTRAL OK LATER TONIGHT. HEAVIER PRECIP /INCLUDING T-STORMS/ CONTINUIONG TO DEVELOP OVER W/NW TX AND MOVE NE ACROSS WARNING AREA OVERNIGHT. HAVE EXPANDED THE ICE STORM WARNING AND ZR ADVISORY FARTHER S...AND PLAN TO HIT THE ICE STORM HARDER AS LATEST QPFS SUGGEST ADDITIONAL 1-2 INCH QPF ACROSS WARNING AREA WHERE WIDESPREAD TREE/POWER LINE DAMAGE ALREADY EXISTS. PRECIP LIKELY TO CHANGE OVER TO MORE PL/SN IN NW LATER ON AS ARCTIC AIR DEEPENS. THIS COULD HOLD DOWN ICE ACCUMULATIONS BUT WILL ONLY MAKE TRAVEL WORSE. WARNING IS STRETCHED TO INCLUDE WASHITA-KINGFISHER-NOBLE-LOGAN-PAYNE COUNTIES WHILE ZR ADVISORY ADDS ONE MORE ROW OF OK COUNTIES TO THE S/SE... MAINLY FOR WED MORNING AS SFC FREEZING LINE EXPECTED TO REACH I-44 REGION AROUND 09-12Z. HAVE ADJUSTED TEMP GRIDS PER 3-H ETA/RUC GRIDS...ABOUT ONLY WAY TO MAINTAIN SHARP THERMAL GRADIENT CURRENTLY ALONG FRONT SE OK AND FALLING TEMPS TONIGHT/WED AS ARCTIC AIR MOVES S. FLOOD WATCH CANCELLED FOR S ZONES AS PRECIP NO LONGER EXPECTED TO BE ENOUGH TO AGGRAVATE SATURATED CONDITIONS THERE. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 28 30 12 32 / 100 80 10 10 HOBART OK 25 28 17 34 / 100 50 10 10 WICHITA FALLS TX 33 35 22 36 / 70 50 10 10 GAGE OK 15 18 10 30 / 100 50 10 10 PONCA CITY OK 26 27 7 28 / 100 80 10 10 DURANT OK 47 52 20 36 / 60 80 10 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...ICE STORM WARNING THROUGH NOON WED OKZ004>022. FREEZING RAIN ADVISORY LATE TONIGHT THROUGH NOON WED OKZ023>030-034>38. TX...NONE. && $$ 24 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 940 AM EST TUE JAN 4 2005 .SHORT TERM /TODAY/...FOG SLOWLY LIFTING ACROSS THE AREA TO ABV DENSE FOG LEVELS SO WILL BE ABLE TO LET DENSE FOG ADVY EXPIRE AND REMOVE FOG WORDING IN UPDATE. VIS SAT PIX SHOWING DEEPEST CLOUD COVER PINNED TO THE COAST WHILE INLAND AREAS ARE NOW CLR. MODEL TIME HEIGHTS SHOW JUST ENOUGH UPR LVL MOISTURE THAT THE AFTN HRS SHOULD PRESENT SCT HIGH CLOUDS SO WILL MAINTAIN PTLY CLDY WORDING FOR ALL AREAS. TEMPS LOOK ON TRACK AND SEEMS TO HANDLE SHARP COASTAL THERMAL GRADIENT WELL. && .MARINE...WITH SURFACE HIGH CENTERED OVER THE SAVANNAH RIVER VALLEY...LIGHT NORTH AND WEST WINDS BEING REPORTED OVER THE WATERS. WILL BE ABLE TO REMOVE MENTION OF FOG WITH THE MORNING UPDATE. THE GRADIENT WILL REMAIN WEAK TODAY...WITH LATEST RUC SHOWING A LIGHT OFFSHORE WIND MUCH OF THE MORNING...BECOMING A LIGHT ONSHORE WIND BY AFTERNOON WITH POSSIBLE SEABREEZE. WILL TRY TO WORD THIS INTO THE ZONES. && .AVIATION...VSBYS STARTING TO IMPROVE OVER THE AREA AFTER A MORNING OF DENSE FOG. VFR CONDITIONS DURING THE AFTERNOON...BUT WILL HIGHLIGHT POTENTIAL FOG ONCE AGAIN FOR TOMORROW MORNING. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ JPC/PY sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 917 AM CST TUE JAN 4 2005 .CURRENT CONDITIONS... 14Z SURFACE ANALYSIS PLACES HIGH PRESSURE CENTERED OVER GEORGIA AND ANOTHER AREA OF HIGH PRESSURE BUILDING INTO THE UPPER MID WEST FROM THE NORTHERN PLAINS. A NEARLY STATIONARY FRONT EXTENDED FROM OFF THE COAST OF NEW ENGLAND THROUGH THE OHIO VALLEY, ACROSS ARKANSAS AND INTO NORTHERN TEXAS. THIS PATTERN HAS MIDDLE TENNESSEE IN THE WARM MOIST AIR CIRCULATING AROUND THE GEORGIA HIGH PRESSURE SYSTEM. ALOFT, A RIDGE WAS CENTERED OVER THE GULF OF MEXICO EXTENDING NORTH ACROSS THE DEEP SOUTH AND THE SOUTH EAST COAST. A LOW CENTER WAS LOCATED JUST OFF THE CALIFORNIA COAST. FLOW ACROSS THE FORECAST AREA WAS FROM THE SOUTHWEST. SEVERAL MINOR UPPER LEVEL DISTURBANCES WERE MOVING WITHIN THE SOUTHWEST FLOW AFFECTING THE FORECAST AREA. CURRENT OHX RADAR INDICATING SCATTERED SHOWERS MOVING NORTHEAST ACROSS MIDDLE TENNESSEE. PRECIPITATION RATES WERE ESTIMATED TO BE LESS THAN ONE TENTH OF AN INCH PER HOUR. MORNING TEMPERATURES RANGED FROM THE MID 50S TO LOWER 60S WITH DEW POINT TEMPERATURES MAINLY IN THE MID 50S. WINDS WERE FROM SOUTH. JUST TO THE NORTH AND WEST, ALONG THE OHIO RIVER, WINDS WERE FROM THE NORTH AND DEW POINT TEMPERATURES WERE IN THE MID TO UPPER 40S. 12Z BNA SOUNDING SHOWS MOIST LAYER FROM SURFACE UP THROUGH 780 MB THEN RELATIVELY DRY UP THROUGH 480 MB. LIFTED INDEX OF 1.2 AND TOTAL TOTALS OF 49 WOULD INDICATE PERIODS OF MODERATE RAIN WOULD BE POSSIBLE. .FORECAST... MORNING RUC HAS THE FRONT LOCATED TO OUR NORTH PUSHING SLOWLY SOUTH AND EAST THROUGH THE DAY BUT...REMAINING JUST NORTH OF MIDDLE TENNESSEE THROUGH MIDNIGHT. UPPER LEVEL LOW OFF THE WEST COAST MOVES EAST WHILE THE GULF RIDGE BUILDS OVER THE FORECAST AREA. AS THE FRONT NUDGES SOUTH AND SOUTHERLY LOW LEVEL FLOW CONTINUES TO PUMP WARM MOIST AIR ACROSS THE AREA, EXPECT SHOWERS AND POSSIBLY A THUNDERSTORM THROUGH THE DAY. && .BNA WATCHES/WARNINGS/ADVISORIES...NONE. && $$ 05 tn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 846 PM CST TUE JAN 4 2005 .UPDATE... SHORT-WAVE WILL PASS NORTH OF SOUTH CENTRAL TEXAS OVERNIGHT INTO WEDNESDAY. FOR TONIGHT, HAVE LOWERED POPS AND DROPPED MENTION OUT WEST WHILE COULD BE SOME STREAMER SHOWERS IN THE EAST. COLD FRONT SLOWLY DROPPING SOUTH FASTER THAN THE BETTER ETA/RUC AND EXPECT IT THROUGH SOUTH CENTRAL TEXAS LATE MORNING TO EVENING. HIGHS IN PARTS OF THE HILLS COULD BE BEFORE NOON AS SHALLOW COLD AIRMASS INVADES. RIGHT REAR QUADRANT OF UPPER JET WILL THEN INDUCE ISENTROPIC LIFT BY THURSDAY KEEPING SKIES MOSTLY CLOUDY. HAVE LOWERED DAYTIME TEMPERATURES ABOUT 5 DEGREES ON THURSDAY FROM PREVIOUS FORECASTS. A WARM ADVECTION PATTERN THEN ERODES THE COLD AIRMASS FROM ABOVE BY SATURDAY AS SHORT-WAVE PASSES. TEMPERATURES FRIDAY NIGHT COULD EVEN SLOWLY RISE. OTHERWISE, ONGOING FORECAST GENERALLY ON TRACK, ALTHOUGH MADE SOME TWEAKS TO WINDS, TEMPERATURES, DEWPOINTS AND RELATED FIELDS TO REFLECT THE ABOVE TRENDS. && .PREV DISCUSSION... STRONG SUBTROPICAL JET THAT DEVELOPED IN LATE DEC 2004 CONTINUES IN FORECASTS THROUGH NEXT WEEK...SIGNALLING CONTINUED MOSTLY CLOUDY WEATHER PATTERN FOR A JANUARY SETTING. SOME MEDIUM RANGE FORECASTS SHOW POSSIBLE CHANGES COMING IN A MID TO LATE JANUARY TIME FRAME...IN A WAY THAT WOULD BRING MORE SUNSHINE AND DRIER DAYS. IN THE MEANTIME...WILL CONTINUE WITH WARM AND MOSTLY CLOUDY THRU WEDNESDAY. CONTINUED WITH CHANCE OF RAIN...SHOWERS OR A FEW THUNDERSTORMS ALONG THE COLD FRONT WEDNESDAY...DIMINISHING WEDNESDAY EVENING FROM THE WEST. FORECASTS SHOW QUICK RETURN FLOW...OVERRUNNING PATTERN DEVELOPING ON THURSDAY...SO WILL SHOW MOSTLY CLOUDY CONDITIONS WITH LIMITED WARMING IN THE DAY. CHANCE OF RAIN SHOWS UP THURSDAY NIGHT AND FRIDAY... AHEAD OF S/W TROF COMING FROM THE WEST. PARTIAL CLEARING PATTERN SHOWS UP IN FORECASTS LATE SATURDAY AND SUNDAY...FOLLOWED BY STRONG SOUTHERLY FLOW RETURNING LATE SUNDAY THROUGH TUESDAY. MONDAY AND TUESDAY OF NEXT WEEK LOOK UNSEASONABLY WARM AGAIN...FOLLOWED BY POSSIBLE PACIFIC FRONT WEDNESDAY NIGHT AND THURSDAY NEXT WEEK. && .EWX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ 04/06/MS tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 840 PM CST TUE JAN 4 2005 .UPDATE... A FEW MINOR CHANGES TO POP/TEMP/WIND FCST PER CURRENT TRENDS AND 00Z MODEL RUNS SEEPING IN. FIRST OFF...UPPER RIDGE HAS ENHANCED ENOUGH UP THROUGH E/SE ZONES THAT FELT A DROP TO SLIGHT CHANCE OR NO POP OVERNIGHT LOOKED REASONABLE (GENERALLY SE OF A LAMPASAS...WACO... TERRELL LINE)...ELEVATED MIXED LAYER (CAP) IS PUTTING A LID ON THINGS WITH BEST SYNOPTIC LIFT AND ISENTROPIC LIFT ONGOING WELL NW OF HERE OVER TX/OK PANHANDLES INTO CNTRL-NRN OK ATTM. AIRMASS WITH ONGOING WET-BULBING IN THOSE AREAS STRONG ENOUGH FOR ANOTHER SLOW PUSH OF COLD FRONT/COOLER TEMPS/AND SOME FOG INTO FAR NWRN COUNTIES (NW OF D/FW) FOR AN UPDATE. TRICKY TO FIGURE OUT WITH JUST SHEER DENSITY PUSHING THIS AIRMASS AGAINST ONGOING SLY LLJ. THIS IS ALSO WHERE BEST LIFTING OVER THE FRONTAL INVERSION AND COOLING ALOFT WILL BE FOR MEASURABLE RAINFALL. CHANCES OF ANY THUNDER SHOULD COME MORE TOWARD 12Z WED IN THIS AREA DOWN TO I-20. IT MUST BE NOTED THAT RUC/ETA20 ARE GENERALLY BEING FOLLOWED FOR THIS SHALLOW ARCTIC AIRMASS AS GFS/ OTHER MODELS AREN'T RESOLVING THIS FEATURE PARTICULARLY WELL... WHICH IS NO SURPRISE. STILL CONTINUE TREND FOR MORNING HIGHS JUST SOUTH OF 12Z FRONTAL BOUNDARY (ALONG-S OF I20/30 CORRIDORS)...WITH RAPIDLY FALLING TEMPS IN THE AFTERNOON WED ALONG WITH DECENT RAIN CHANCES WITH OCNL THUNDER IN INCREASING ELEVATED LAPSE RATES. THIS WAS LEFT ALONE FOR NOW AND WILL LET NEXT SHIFT RESOLVE MORE OF THIS LATER. STILL NOT OUT OF THE QUESTION FOR A BRIEF/QUICK CHANGEOVER TO FREEZING RAIN OVER FAR NWRN COUNTIES ON WED BEFORE PRECIP SHUTS OFF. AT THIS TIME...THINKING MAIN GAME THERE WILL REMAIN NORTH OF RED RIVER INTO OK. UPDATES ON THE WAY. 05/ && .AVIATION... 600 PM CST ANOTHER COMPLICATED AVIATION FORECAST THIS EVENING...WITH A COMBINATION OF IFR/MVFR CIGS AND VSBYS REPORTED AT LOCAL AIRPORTS. WE GENERALLY ANTICIPATE TEMPORARY IFR CONDITIONS TO CONTINUE THROUGH 05/03-05Z...BEFORE PRESSURE FALLS TO THE NORTHWEST OF THE REGION FORCE SELY SURFACE WINDS TO STRENGTHEN...ALLOWING INCREASED MIXING TO REDUCE THE COVERAGE OF FG/BR. ARCTIC FRONTAL BOUNDARY WILL LIKELY PUSH THROUGH NORTH TEXAS SOONER THAN PROGGED BY CURRENT MODEL GUIDANCE...AND WILL USE THE 05/11-15Z WINDOW FOR FRONTAL PASSAGE... WITH AN ASSOCIATED CHANCE FOR TSRA. MVFR STRATUS IS LIKELY FOR A GOOD PORTION OF THE DAY FOLLOWING FROPA...ALONG WITH 15G25 NWLY WINDS. SOME CLEARING LIKELY TOWARD END OF THE FORECAST PERIOD... ESPECIALLY AT THE METROPLEX AIRPORTS. 65/DD && .DISCUSSION... FRONT HAS RETREATED TO THE NORTH AND IS NOW DRAPED ALONG THE NW CWA BORDER WHERE IT WILL LIE STATIONARY THROUGH MIDNIGHT. THEN IT WILL SURGE SOUTHWARD AFTER MIDNIGHT AND PUSH THROUGH THE CWA WEDNESDAY. ARCTIC 1045 MB HIGH PRESSURE HAS ENTERED THE NORTHERN PLAINS TODAY WITH VERY COLD AIR NOW MOVING RAPIDLY SOUTH ALONG THE FRONT RANGE OF THE ROCKIES. TEMPS HAVE FALLEN TO SINGLE DIGITS AND TEENS ACROSS NEBRASKA AND THIS AIR WILL CONTINUE TO PUSH SOUTH INTO KANSAS AND OKLAHOMA TONIGHT. 850 TEMPS ARE NOT EXCESSIVELY COLD GIVEN THE SURFACE TEMPS AND THESE SHALLOW ARCTIC AIRMASSES TYPICALLY ARE HANDLED BEST BY THE RUC/ETA MODELS. THE ETA IS THE FASTEST/COLDEST OF THE MODELS BUT IT MAY BE A BIT SLOW/WARM COMPARED TO THE RUC WHICH ONLY GOES OUT 12 HOURS. THEREFORE HAVE GONE A LITTLE COOLER AND FASTER THAN THE 18Z ETA PER RUC EXTRAPOLATION/TRENDS. UPPER SHORTWAVE TROUGH WILL EJECT OUT INTO THE PLAINS TOMORROW MORNING WITH THE BRUNT OF THE PRECIPITATION IS EXPECTED ACROSS THE NORTH/EAST. A LINE OF CONVECTION IS EXPECTED TO FORM ALONG THE FRONT BY THE LATE MORNING AND AFTERNOON OVER THE CENTRAL AND SOUTH...WITH ISENTROPIC LIFT BEHIND THE ACCELERATING FRONT ACTING AS THE MECHANISM FOR AN EPISODE OF POST FRONTAL RAINS OVER THE NORTH. MID SHIFT CAN ASSESS THE FLOOD POTENTIAL...BUT BASIN QPF SHOULD REMAIN BELOW 0.5 INCH OVER THE NORTHEAST. SURFACE TEMPS WILL FALL DRAMATICALLY BEHIND THE FRONT AND DROP BELOW FREEZING OVER THE NW BY THE AFTERNOON. HAVE INCLUDED A SLIGHT CHANCE OF LIGHT FREEZING RAIN OVER THE EXTREME NW COUNTIES. GROUND TEMPS WILL BE TOO WARM FOR ANY ACCUMULATIONS EVEN IF -FZRA DID MATERIALIZE SO ADVISORIES WILL NOT BE REQUIRED. HAVE FOLLOWED THE MET GUIDANCE FOR TEMPS SINCE THE COLDER ETA LOOKS THE MOST REASONABLE. MODELS ALSO SHOW TEMPS IN THE MID 30S THURSDAY NIGHT WITH ANOTHER COUPLE OF SHORTWAVES CREATING OVERRUNNING RAINS THROUGH SATURDAY. NOT PARTICULARLY CONCERNED ABOUT FREEZING RAIN THURSDAY NIGHT AS 850 TEMPS WARM SEVERAL DEGREES SO THAT THE CLOUD COVER SHOULD RADIATE WARMER TEMPS TOWARD THE SURFACE BY FRIDAY MORNING. THIS WILL BE SOMETHING TO KEEP AN EYE ON IN CASE SURFACE TEMPS ARE 5-10 COLDER THAN CURRENTLY FORECAST. OTHERWISE...DRY WX WITH MODERATING TEMPS FOR SUN-TUE AS MOIST/SOUTHERLY FLOW RETURNS. TR/92 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 59 62 26 41 / 40 60 10 10 WACO, TX 62 66 30 44 / 20 40 20 10 PARIS, TX 52 61 23 39 / 40 70 20 10 DENTON, TX 50 53 25 40 / 50 60 10 10 MCKINNEY, TX 55 60 24 40 / 40 70 10 10 DALLAS, TX 59 63 26 41 / 40 60 10 10 TERRELL, TX 61 66 26 42 / 30 70 20 10 CORSICANA, TX 62 68 30 43 / 20 50 30 10 TEMPLE, TX 63 67 32 46 / 20 40 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... TX...NONE. && $$ tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 715 PM CST TUE JAN 4 2005 .UPDATED... DENSE FOG HAS FORMED OVER THE EXTREME NORTHEAST FA BEHIND THE COLD FRONT WITH VISIBILITIES LESS THAN 1/4 MILE. HAVE UPDATED THE ZONES AND ISSUED A DENSE FOG ADVISORY THROUGH 4 AM FOR SCURRY...BORDEN AND DAWSON COUNTIES. .SHORT TERM... STRONG MID/UPPER LOW NOW CENTERED OVER SOUTHERN CA IS SLOWLY BEGINNING TO MOVE EAST. AN UPPER LEVEL JET MAX OF 130+KT IS CURRENTLY ROTATING AROUND THE SOUTHERN SIDE OF THIS LOW OVER NORTHERN OLD MEXICO...THEN NORTHEAST INTO SOUTHERN NM. THIS SPEED MAX WILL COMBINE WITH GOOD MOISTURE...AND PVA OVER NM TO AID IN THE DEVELOPMENT OF MORE PRECIP OVER SOUTHERN NM. LAPSE RATES WILL DECREASE THROUGHOUT THE NIGHT...BUT WILL START NEAR 6C/KM...SO WE MAY GET SOME TSRA OUT OF THE ACTIVITY EARLY ON...ESPECIALLY CONSIDERING THAT WITH A SIMILAR SET UP LAST NIGHT WE DID GET SOME THUNDER OVER OUR SERN NM COUNTIES. NOT EXPECTING CONVECTION IN NM TO REACH SEVERE LIMITS HOWEVER. IF CONVECTION CAN HOLD TOGETHER AND MAKE IT INTO EASTERN AREAS...LAPSE RATES AND INSTABILITY INCREASE... THUNDERSTORMS COULD BECOME STRONGER...BUT STILL NOT EXPECTING STORMS TO BECOME SEVERE. WILL KEEP HIGHEST POPS OVER SERN NM...AND THE NORTHERN COUNTIES OF THE CWA...SINCE THESE AREAS WILL BE CLOSEST TO MID AND UPPER LEVEL DYNAMICS OF THIS SYSTEM. AT THE SURFACE...THE COLD FRONT HAD LIFTED BACK NORTH OF BIG SPRING BY 17Z. COULD SEE THE EDGE OF THE FRONT AT 1930Z USING VIS IMAGERY AS A LINE OF LOW CLOUDS EXTENDS ROUGHLY WEST TO EAST FROM ANDREWS COUNTY...THEN ACROSS THE NORTHERN PORTIONS OF MARTIN...HOWARD AND MITCHELL COUNTIES. WILL WEIGHT FORECAST FOR TONIGHT TOWARD THE RUC SOLUTION OF THIS BOUNDARY...AS THE ETA AND GFS HAVE NOT HAD A LOT OF SUCCESS RESOLVING IT. WILL KEEP THE COLD AIR IN PLACE ACROSS THE NORTHEASTERN COUNTIES OF OUR CWA. A PACIFIC FRONT IS ALSO EXPECTED TO MOVE IN FROM THE WEST FOLLOWING THE PRECIP. WEST WINDS AND LOWER DEWPOINTS WILL MAKE THEIR WAY INTO THE SOUTHEASTERN NM PLAINS BY 12Z TOMORROW MORNING. && .LONG TERM... OVERALL...MODELS LOOK TO BE WELL INITIALIZED THIS MORNING. WE'RE LOCKED INTO A NEGATIVE PNA PATTERN WITH VERY STRONG POSITIVE HEIGHT ANOMALIES OVER THE NORTHERN PACIFIC AND LESSER...BUT ABOVE NORMAL... HEIGHT ANOMALIES OVER THE EASTERN CONUS...AND THIS PATTERN IS FORECAST TO CONTINUE THROUGH AT LEAST EARLY NEXT WEEK. THE ETA IS THE FARTHEST SOUTH WITH RESPECT TO THE COLD FRONT THAT PUSHES INTO THE NORTHEASTERN CWFA WEDNESDAY...FITTING OUR CONCEPTUAL MODEL ON HOW COLD FRONTS BEHAVE HEREABOUTS...AND WE WILL TREND HEAVILY TOWARD ITS SOLUTION WEDNESDAY AND THURSDAY. BY FRIDAY...THE OPERATIONAL GFS APPEARS TO TRACK WITHIN THE GFS ENSEMBLE MEANS AS WELL AS THE SOLUTIONS OFFERED BY THE GEM AND ECMWF...THUS WE WILL TREND TOWARD ITS SOLUTION THROUGH EARLY NEXT WEEK. BY THE BEGINNING OF THE LONG TERM PERIOD...PRECIP WILL BE ENDING ACROSS THE NORTHEASTERN CWFA AS LIFT ASSOCIATED WITH THE EXITING SHORTWAVE TROUGH TRANSLATES AWAY FROM THE REGION. IN ITS WAKE... MODIFIED ARCTIC AIR WILL WORK ITS WAY INTO THE NORTHEASTERN CWFA WEDNESDAY. THIS FRONT SHOULD MAKE IT AS FAR AS THE PECOS RIVER VALLEY THURSDAY NIGHT BEFORE BECOMING STATIONARY. MARKED COOLING IS NOTED AT 850 HPA AS TEMPERATURES FALL BELOW 5C ACROSS THE WESTERN LOW ROLLING PLAINS. THIS ALONG WITH CONTINUED CLOUDINESS AND MODEST LOW LEVEL COLD AIR ADVECTION WILL KEEP TEMPERATURES BELOW NORMAL OVER THE NORTHEASTERN THIRD OF THE CWFA THURSDAY. BY THURSDAY NIGHT... HOWEVER...HEIGHTS BEGIN FALL OVER THE WESTERN CONUS AS ANOTHER SHORTWAVE TROUGH RELOADS INTO THE MEAN LONGWAVE POSITION. SURFACE CYCLOGENESIS WILL RESUME ALONG THE LEE SLOPES OF THE CENTRAL ROCKIES IN RESPONSE TO INCREASING ZONAL FLOW DOWNSTREAM OF THIS FEATURE... WITH THE END RESULT BEING VEERING OF SURFACE WINDS BACK IN THE COLD AIR AND SUBSEQUENT FRONTOLYSIS ON FRIDAY. INCREASING WESTERLY WINDS AT THE SURFACE ALONG WITH GOOD THICKNESS WARMING WILL LEAD TO A WARMUP BEGINNING FRIDAY...WITH ABOVE NORMAL HIGHS RETURNING TO THE REGION SATURDAY AND CONTINUING INTO THE MIDDLE OF NEXT WEEK. GULF MOISTURE WILL SLOWLY INCREASE ACROSS THE EASTERN HALF OF THE AREA... AMELIORATING LOW TEMPERATURES ACROSS THESE AREAS AS WELL. A SERIES OF SHORTWAVE TROUGHS EMBEDDED IN THE FAST SOUTHWESTERLY FLOW ALOFT WILL TRANSIT THE REGION AS WELL...BUT WITH THE BEST DYNAMICAL LIFT FORECAST TO REMAIN WELL TO THE NORTH...SIG WX NIL THROUGH EARLY NEXT WEEK. HOWEVER...WINDY CONDITIONS MAY BECOME AN ISSUE SUNDAY THROUGH TUESDAY...PARTICULARLY ACROSS THE GUADALUPES WHERE EXTENDED PROGS SUGGEST CONDITIONS FAVORABLE FOR MOUNTAIN WAVE DEVELOPMENT. THE PREVIOUS FORECAST WAS DRY AND WE WILL KEEP IT THAT WAY. WE'VE LOWERED TEMPERATURES WEDNESDAY AND THURSDAY BEHIND THE COLD FRONT BUT NOT QUITE AS MUCH AS INDICATED BY THE LATEST ETA GUIDANCE. WE WILL ATTENUATE THE FORECASTED WARMUP FRIDAY GIVEN THE MODELS' PROPENSITY TO ERODE ARCTIC AIRMASSES TOO FAST...BUT BY SATURDAY...THE PREVIOUS FORECAST LOOKS GOOD WITH ONLY MINOR NUDGES NECESSARY HERE AND THERE. DID INCREASE WINDS THIS WEEKEND INTO EARLY NEXT WEEK...ESPECIALLY ACROSS THE GUADALUPES SUNDAY THROUGH TUESDAY. WE HAVE TRENDED SKY GRIDS STRONGLY TOWARD THE OPERATIONAL GFS SOLUTION AS THIS MODEL TYPICALLY DOES BEST IN DEPICTING UPPER LEVEL SUBTROPICAL MOISTURE FEEDS DURING EASTERN PACIFIC SPLIT FLOW REGIMES. LASTLY...DEWPOINT GRIDS REFLECT A BLEND OF THE OPERATIONAL GFS AND GFS MOS SOLUTIONS. && .PRELIMINARY POINT TEMPS/POPS... BIG SPRING TX 44 58 29 46 / 30 10 0 0 CARLSBAD NM 44 58 29 55 / 40 10 0 0 DRYDEN TX 57 70 40 55 / 10 0 10 0 FORT STOCKTON TX 49 58 36 56 / 20 0 0 0 GUADALUPE PASS TX 37 48 31 52 / 40 0 10 0 HOBBS NM 43 56 25 53 / 40 10 0 0 MARFA TX 40 56 29 59 / 20 0 10 0 MIDLAND INTL AIRPORT TX 48 59 30 48 / 30 10 0 0 ODESSA TX 48 58 29 49 / 30 10 0 0 WINK TX 48 61 31 59 / 30 10 0 0 && .MAF WATCHES/WARNINGS/ADVISORIES... TX...NONE. NM...NONE. && $$ 20/70 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SAN ANGELO TX 705 PM CST TUE JAN 4 2005 .UPDATE... CALLS AROUND THE AREA SUGGEST THAT FOG HAS DROPPED VISIBILITIES TO AT OR BELOW A QUARTER MILE ACROSS AT LEAST A GOOD PART OF THE BIG COUNTRY NORTH OF THE FRONT. HAVE GONE AHEAD AND ISSUED A DENSE FOG ADVISORY THROUGH MIDNIGHT. SOME HOPE THAT RAIN APPROACHES FROM THE WEST AND BETTER MIXING TAKES PLACE...VISIBILITIES WILL RISE ENOUGH THAT THE ADVISORY CAN BE ALLOWED TO EXPIRE. && .PREV DISCUSSION... FORECAST ACROSS THE BIG COUNTRY THIS EVENING CONTINUES TO BE A DIFFICULT PROCESS. COLD FRONT WOBBLED BACK THROUGH THE EAST SIDE OF ABILENE WITHIN THE LAST HOUR...DROPPING TEMPERATURES FROM THE LOWER 70S BACK INTO THE MID 50S AT ABILENE REGIONAL AIRPORT. FRONT HAD APPARENTLY NEVER MADE IT THROUGH THE WEST SIDE OF ABILENE...WHERE THE KDYX OBS STAYED IN THE 50S ALL DAY. SIMILAR TO LAST NIGHT...WARM ADVECTION ABOVE THE FRONTAL SURFACE SHOULD DROP VISIBILITIES AND CEILINGS AS FOG AND DRIZZLE DEVELOP. EXPECT TO REMAIN STATIONARY THROUGH THE EVENING...AND THEN BEGIN TO PUSH SOUTH LATER TONIGHT. FRONT WAS EXPECTED TO PUSH BACK THROUGH LATER TONIGHT ANYWAY...SO CURRENT FORECAST LOWS LOOK GOOD...ALTHOUGH WILL NEED ADJUST HOURLY TRENDS. OUT WEST...AREA OF CONVECTION HAS BLOSOMMED ACROSS THE WESTERN PERMIAN BASIN. ALREADY CARRYING DECENT POPS ACROSS THE BIG COUNTRY AND THIS LOOKS REASONABLE. GIVEN THE DYNAMIC AND CHANGEABLE WEATHER...DO NOT EXPECT THIS TO BE THE LAST UPDATE THIS EVENING. A COLD FRONT STALLED ACROSS THE BIG COUNTRY HAS BEEN A TRICKY FORECAST ISSUE EVEN IN THE SHORT TERM. THIS MORNING IT LOOKED LIKE WITH THE COLD AIR THAT THE FRONT WOULD NOT MOVE MUCH...BUT THE FRONT SLOWLY EDGED NORTH INTO THE NORTHERN BIG COUNTRY COUNTIES. THE FRONT IS NOT EXPECTED TO MOVE MUCH ONCE THE SUN SETS. ALOFT... STRONG SW UPPER FLOW CONTINUES WITH A STRONG UPPER JET PUSHING THROUGH THE BAJA TOWARDS EL PASO AS SEEN IN WATER VAPOR IMAGES. THIS JET STREAK SHOULD MOVE INTO W TX EARLY TONIGHT WITH THE MAIN TROUGH MOVING INTO THE PLAINS WEDNESDAY MORNING. THE MAIN FORECAST QUESTIONS DEPEND ON THE POSITION OF THE FRONT OVER THE BIG COUNTRY AND THE SURGE OF ARCTIC AIR WEDNESDAY MORNING. LATEST RUC AND MESO ETA MODEL RUNS HAVE A GOOD HANDLE ON THE SFC FEATURES AND TEMPS. GFS HAS BEEN WAY OFF ON TEMPS AND CANNOT RESOLVE THE SHALLOW COLD AIR IN PLACE. STICKING WITH THE RUC AND MESO ETA WHICH ARE RESOLVING THE COLD AIR MASS IN PLACE AND THE SURGING ARCTIC AIR IN THE CENTRAL PLAINS...THE FRONT OVER THE BIG COUNTRY SHOULD NOT MOVE MUCH TONIGHT. THE FRONT SHOULD BEGIN THE MAKE SOME PROGRESS SOUTH WED MORNING AS THE ARCTIC AIR MEETS THE STALLED FRONT AND IT SHOULD PUSH THROUGH MUCH OF W CENTRAL TX BY 18Z WED. IT IS POSSIBLE THAT THE FRONT COULD PUSH THROUGH EARLIER THAN PROGGED GIVEN THERE IS NOTHING TO STOP THE ARCTIC AIR AND IT IS NOT FAR AWAY AS IT HAS ALREADY PUSHED INTO CENTRAL KS. WITH THAT...TEMPS SHOULD SLOWLY DROP THROUGH THE DAY WED WITH THE BIG COUNTRY NOT WARMING UP MUCH AT ALL. PRECIP CHANCES ARE ALSO AN ISSUE. WATER VAPOR IMAGES SHOW DRIER AIR WORKING INTO THE REGION ALOFT. THERE WILL BE SOME STRONG DYNAMICAL FORCING WITH THE JET STREAK TONIGHT SO CHANCE POPS ARE LEFT FOR THE BIG COUNTRY WITH LOWER POPS FOR THE CONCHO VALLEY SOUTHWARD. WEDNESDAY IS TRICKY AS WELL AS THE MESO ETA KEEPS MOST OF THE PRECIP AND FRONTAL FORCING EAST OF OUR FORECAST AREA. SOME POPS ARE LEFT IN THE FORECAST FOR WEDNESDAY MAINLY FOR THE BIG COUNTRY AND HEARTLAND WITH THE FRONTAL FORCING. AFTER THE FRONT...HIGH PRESSURE BUILDS IN THE REGION WHICH WILL PUT A CAP ON PRECIP CHANCES. THURSDAY THROUGH THE WEEKEND LOOKS LIKE THE UPPER FLOW BECOMES MORE ZONAL WITH SOME TROUGHING OCCURRING OVER THE PACIFIC SATURDAY AND SUNDAY. DRY CONDITIONS ARE EXPECTED ALTHOUGH THE GFS DOES GENERATE SOME PRECIP OVER THE HILL COUNTRY WITH WAA AND THE DEVELOPMENT OF A GULF LOW IN S TX. RIGHT NOW THINK THAT MOST OF THE PRECIP WILL STAY SOUTH OF THE AREA AND QUICKLY MOVE EAST. DRIER AIR IS EXPECTED TO PUSH INTO W CENTRAL TX ON SATURDAY WHICH WILL ALSO KEEP ANY POPS TO THE EAST OF THE FORECAST AREA. EARLY NEXT WEEK THE UPPER TROUGH OFF THE WEST COAST BEGINS TO MOVE EAST. THE PATTERN IS SIMILAR TO THIS LAST SYSTEM BUT COULD PULL OUT FARTHER NORTH INTO THE CENTRAL PLAINS. && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 99/99 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 600 PM CST TUE JAN 4 2005 .AVIATION... ANOTHER COMPLICATED AVIATION FORECAST THIS EVENING...WITH A COMBINATION OF IFR/MVFR CIGS AND VSBYS REPORTED AT LOCAL AIRPORTS. WE GENERALLY ANTICIPATE TEMPORARY IFR CONDITIONS TO CONTINUE THROUGH 05/03-05Z...BEFORE PRESSURE FALLS TO THE NORTHWEST OF THE REGION FORCE SELY SURFACE WINDS TO STRENGTHEN...ALLOWING INCREASED MIXING TO REDUCE THE COVERAGE OF FG/BR. ARCTIC FRONTAL BOUNDARY WILL LIKELY PUSH THROUGH NORTH TEXAS SOONER THAN PROGGED BY CURRENT MODEL GUIDANCE...AND WILL USE THE 05/11-15Z WINDOW FOR FRONTAL PASSAGE... WITH AN ASSOCIATED CHANCE FOR TSRA. MVFR STRATUS IS LIKELY FOR A GOOD PORTION OF THE DAY FOLLOWING FROPA...ALONG WITH 15G25 NWLY WINDS. SOME CLEARING LIKELY TOWARD END OF THE FORECAST PERIOD... ESPECIALLY AT THE METROPLEX AIRPORTS. 65/DD && .DISCUSSION... FRONT HAS RETREATED TO THE NORTH AND IS NOW DRAPED ALONG THE NW CWA BORDER WHERE IT WILL LIE STATIONARY THROUGH MIDNIGHT. THEN IT WILL SURGE SOUTHWARD AFTER MIDNIGHT AND PUSH THROUGH THE CWA WEDNESDAY. ARCTIC 1045 MB HIGH PRESSURE HAS ENTERED THE NORTHERN PLAINS TODAY WITH VERY COLD AIR NOW MOVING RAPIDLY SOUTH ALONG THE FRONT RANGE OF THE ROCKIES. TEMPS HAVE FALLEN TO SINGLE DIGITS AND TEENS ACROSS NEBRASKA AND THIS AIR WILL CONTINUE TO PUSH SOUTH INTO KANSAS AND OKLAHOMA TONIGHT. 850 TEMPS ARE NOT EXCESSIVELY COLD GIVEN THE SURFACE TEMPS AND THESE SHALLOW ARCTIC AIRMASSES TYPICALLY ARE HANDLED BEST BY THE RUC/ETA MODELS. THE ETA IS THE FASTEST/COLDEST OF THE MODELS BUT IT MAY BE A BIT SLOW/WARM COMPARED TO THE RUC WHICH ONLY GOES OUT 12 HOURS. THEREFORE HAVE GONE A LITTLE COOLER AND FASTER THAN THE 18Z ETA PER RUC EXTRAPOLATION/TRENDS. UPPER SHORTWAVE TROUGH WILL EJECT OUT INTO THE PLAINS TOMORROW MORNING WITH THE BRUNT OF THE PRECIPITATION IS EXPECTED ACROSS THE NORTH/EAST. A LINE OF CONVECTION IS EXPECTED TO FORM ALONG THE FRONT BY THE LATE MORNING AND AFTERNOON OVER THE CENTRAL AND SOUTH...WITH ISENTROPIC LIFT BEHIND THE ACCELERATING FRONT ACTING AS THE MECHANISM FOR AN EPISODE OF POST FRONTAL RAINS OVER THE NORTH. MID SHIFT CAN ASSESS THE FLOOD POTENTIAL...BUT BASIN QPF SHOULD REMAIN BELOW 0.5 INCH OVER THE NORTHEAST. SURFACE TEMPS WILL FALL DRAMATICALLY BEHIND THE FRONT AND DROP BELOW FREEZING OVER THE NW BY THE AFTERNOON. HAVE INCLUDED A SLIGHT CHANCE OF LIGHT FREEZING RAIN OVER THE EXTREME NW COUNTIES. GROUND TEMPS WILL BE TOO WARM FOR ANY ACCUMULATIONS EVEN IF -FZRA DID MATERIALIZE SO ADVISORIES WILL NOT BE REQUIRED. HAVE FOLLOWED THE MET GUIDANCE FOR TEMPS SINCE THE COLDER ETA LOOKS THE MOST REASONABLE. MODELS ALSO SHOW TEMPS IN THE MID 30S THURSDAY NIGHT WITH ANOTHER COUPLE OF SHORTWAVES CREATING OVERRUNNING RAINS THROUGH SATURDAY. NOT PARTICULARLY CONCERNED ABOUT FREEZING RAIN THURSDAY NIGHT AS 850 TEMPS WARM SEVERAL DEGREES SO THAT THE CLOUD COVER SHOULD RADIATE WARMER TEMPS TOWARD THE SURFACE BY FRIDAY MORNING. THIS WILL BE SOMETHING TO KEEP AN EYE ON IN CASE SURFACE TEMPS ARE 5-10 COLDER THAN CURRENTLY FORECAST. OTHERWISE...DRY WX WITH MODERATING TEMPS FOR SUN-TUE AS MOIST/SOUTHERLY FLOW RETURNS. TR/92 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 59 62 26 41 / 40 60 10 10 WACO, TX 62 66 30 44 / 20 40 20 10 PARIS, TX 52 61 23 39 / 40 70 20 10 DENTON, TX 50 53 25 40 / 50 60 10 10 MCKINNEY, TX 55 60 24 40 / 40 70 10 10 DALLAS, TX 59 63 26 41 / 40 60 10 10 TERRELL, TX 61 66 26 42 / 30 70 20 10 CORSICANA, TX 62 68 30 43 / 20 50 30 10 TEMPLE, TX 63 67 32 46 / 20 40 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... TX...NONE. && $$ tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SAN ANGELO TX 552 PM CST TUE JAN 4 2005 .UPDATE... FORECAST ACROSS THE BIG COUNTRY THIS EVENING CONTINUES TO BE A DIFFICULT PROCESS. COLD FRONT WOBBLED BACK THROUGH THE EAST SIDE OF ABILENE WITHIN THE LAST HOUR...DROPPING TEMPERATURES FROM THE LOWER 70S BACK INTO THE MID 50S AT ABILENE REGIONAL AIRPORT. FRONT HAD APPARENTLY NEVER MADE IT THROUGH THE WEST SIDE OF ABILENE...WHERE THE KDYX OBS STAYED IN THE 50S ALL DAY. SIMILAR TO LAST NIGHT...WARM ADVECTION ABOVE THE FRONTAL SURFACE SHOULD DROP VISIBILITIES AND CEILINGS AS FOG AND DRIZZLE DEVELOP. EXPECT TO REMAIN STATIONARY THROUGH THE EVENING...AND THEN BEGIN TO PUSH SOUTH LATER TONIGHT. FRONT WAS EXPECTED TO PUSH BACK THROUGH LATER TONIGHT ANYWAY...SO CURRENT FORECAST LOWS LOOK GOOD...ALTHOUGH WILL NEED ADJUST HOURLY TRENDS. OUT WEST...AREA OF CONVECTION HAS BLOSOMMED ACROSS THE WESTERN PERMIAN BASIN. ALREADY CARRYING DECENT POPS ACROSS THE BIG COUNTRY AND THIS LOOKS REASONABLE. GIVEN THE DYNAMIC AND CHANGEABLE WEATHER...DO NOT EXPECT THIS TO BE THE LAST UPDATE THIS EVENING. && .PREV DISCUSSION... A COLD FRONT STALLED ACROSS THE BIG COUNTRY HAS BEEN A TRICKY FORECAST ISSUE EVEN IN THE SHORT TERM. THIS MORNING IT LOOKED LIKE WITH THE COLD AIR THAT THE FRONT WOULD NOT MOVE MUCH...BUT THE FRONT SLOWLY EDGED NORTH INTO THE NORTHERN BIG COUNTRY COUNTIES. THE FRONT IS NOT EXPECTED TO MOVE MUCH ONCE THE SUN SETS. ALOFT... STRONG SW UPPER FLOW CONTINUES WITH A STRONG UPPER JET PUSHING THROUGH THE BAJA TOWARDS EL PASO AS SEEN IN WATER VAPOR IMAGES. THIS JET STREAK SHOULD MOVE INTO W TX EARLY TONIGHT WITH THE MAIN TROUGH MOVING INTO THE PLAINS WEDNESDAY MORNING. THE MAIN FORECAST QUESTIONS DEPEND ON THE POSITION OF THE FRONT OVER THE BIG COUNTRY AND THE SURGE OF ARCTIC AIR WEDNESDAY MORNING. LATEST RUC AND MESO ETA MODEL RUNS HAVE A GOOD HANDLE ON THE SFC FEATURES AND TEMPS. GFS HAS BEEN WAY OFF ON TEMPS AND CANNOT RESOLVE THE SHALLOW COLD AIR IN PLACE. STICKING WITH THE RUC AND MESO ETA WHICH ARE RESOLVING THE COLD AIR MASS IN PLACE AND THE SURGING ARCTIC AIR IN THE CENTRAL PLAINS...THE FRONT OVER THE BIG COUNTRY SHOULD NOT MOVE MUCH TONIGHT. THE FRONT SHOULD BEGIN THE MAKE SOME PROGRESS SOUTH WED MORNING AS THE ARCTIC AIR MEETS THE STALLED FRONT AND IT SHOULD PUSH THROUGH MUCH OF W CENTRAL TX BY 18Z WED. IT IS POSSIBLE THAT THE FRONT COULD PUSH THROUGH EARLIER THAN PROGGED GIVEN THERE IS NOTHING TO STOP THE ARCTIC AIR AND IT IS NOT FAR AWAY AS IT HAS ALREADY PUSHED INTO CENTRAL KS. WITH THAT...TEMPS SHOULD SLOWLY DROP THROUGH THE DAY WED WITH THE BIG COUNTRY NOT WARMING UP MUCH AT ALL. PRECIP CHANCES ARE ALSO AN ISSUE. WATER VAPOR IMAGES SHOW DRIER AIR WORKING INTO THE REGION ALOFT. THERE WILL BE SOME STRONG DYNAMICAL FORCING WITH THE JET STREAK TONIGHT SO CHANCE POPS ARE LEFT FOR THE BIG COUNTRY WITH LOWER POPS FOR THE CONCHO VALLEY SOUTHWARD. WEDNESDAY IS TRICKY AS WELL AS THE MESO ETA KEEPS MOST OF THE PRECIP AND FRONTAL FORCING EAST OF OUR FORECAST AREA. SOME POPS ARE LEFT IN THE FORECAST FOR WEDNESDAY MAINLY FOR THE BIG COUNTRY AND HEARTLAND WITH THE FRONTAL FORCING. AFTER THE FRONT...HIGH PRESSURE BUILDS IN THE REGION WHICH WILL PUT A CAP ON PRECIP CHANCES. THURSDAY THROUGH THE WEEKEND LOOKS LIKE THE UPPER FLOW BECOMES MORE ZONAL WITH SOME TROUGHING OCCURRING OVER THE PACIFIC SATURDAY AND SUNDAY. DRY CONDITIONS ARE EXPECTED ALTHOUGH THE GFS DOES GENERATE SOME PRECIP OVER THE HILL COUNTRY WITH WAA AND THE DEVELOPMENT OF A GULF LOW IN S TX. RIGHT NOW THINK THAT MOST OF THE PRECIP WILL STAY SOUTH OF THE AREA AND QUICKLY MOVE EAST. DRIER AIR IS EXPECTED TO PUSH INTO W CENTRAL TX ON SATURDAY WHICH WILL ALSO KEEP ANY POPS TO THE EAST OF THE FORECAST AREA. EARLY NEXT WEEK THE UPPER TROUGH OFF THE WEST COAST BEGINS TO MOVE EAST. THE PATTERN IS SIMILAR TO THIS LAST SYSTEM BUT COULD PULL OUT FARTHER NORTH INTO THE CENTRAL PLAINS. && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 350 PM CST TUE JAN 4 2005 .DISCUSSION... FRONT HAS RETREATED TO THE NORTH AND IS NOW DRAPED ALONG THE NW CWA BORDER WHERE IT WILL LIE STATIONARY THROUGH MIDNIGHT. THEN IT WILL SURGE SOUTHWARD AFTER MIDNIGHT AND PUSH THROUGH THE CWA WEDNESDAY. ARCTIC 1045 MB HIGH PRESSURE HAS ENTERED THE NORTHERN PLAINS TODAY WITH VERY COLD AIR NOW MOVING RAPIDLY SOUTH ALONG THE FRONT RANGE OF THE ROCKIES. TEMPS HAVE FALLEN TO SINGLE DIGITS AND TEENS ACROSS NEBRASKA AND THIS AIR WILL CONTINUE TO PUSH SOUTH INTO KANSAS AND OKLAHOMA TONIGHT. 850 TEMPS ARE NOT EXCESSIVELY COLD GIVEN THE SURFACE TEMPS AND THESE SHALLOW ARCTIC AIRMASSES TYPICALLY ARE HANDLED BEST BY THE RUC/ETA MODELS. THE ETA IS THE FASTEST/COLDEST OF THE MODELS BUT IT MAY BE A BIT SLOW/WARM COMPARED TO THE RUC WHICH ONLY GOES OUT 12 HOURS. THEREFORE HAVE GONE A LITTLE COOLER AND FASTER THAN THE 18Z ETA PER RUC EXTRAPOLATION/TRENDS. UPPER SHORTWAVE TROUGH WILL EJECT OUT INTO THE PLAINS TOMORROW MORNING WITH THE BRUNT OF THE PRECIPITATION IS EXPECTED ACROSS THE NORTH/EAST. A LINE OF CONVECTION IS EXPECTED TO FORM ALONG THE FRONT BY THE LATE MORNING AND AFTERNOON OVER THE CENTRAL AND SOUTH...WITH ISENTROPIC LIFT BEHIND THE ACCELERATING FRONT ACTING AS THE MECHANISM FOR AN EPISODE OF POST FRONTAL RAINS OVER THE NORTH. MID SHIFT CAN ASSESS THE FLOOD POTENTIAL...BUT BASIN QPF SHOULD REMAIN BELOW 0.5 INCH OVER THE NORTHEAST. SURFACE TEMPS WILL FALL DRAMATICALLY BEHIND THE FRONT AND DROP BELOW FREEZING OVER THE NW BY THE AFTERNOON. HAVE INCLUDED A SLIGHT CHANCE OF LIGHT FREEZING RAIN OVER THE EXTREME NW COUNTIES. GROUND TEMPS WILL BE TOO WARM FOR ANY ACCUMULATIONS EVEN IF -FZRA DID MATERIALIZE SO ADVISORIES WILL NOT BE REQUIRED. HAVE FOLLOWED THE MET GUIDANCE FOR TEMPS SINCE THE COLDER ETA LOOKS THE MOST REASONABLE. MODELS ALSO SHOW TEMPS IN THE MID 30S THURSDAY NIGHT WITH ANOTHER COUPLE OF SHORTWAVES CREATING OVERRUNNING RAINS THROUGH SATURDAY. NOT PARTICULARLY CONCERNED ABOUT FREEZING RAIN THURSDAY NIGHT AS 850 TEMPS WARM SEVERAL DEGREES SO THAT THE CLOUD COVER SHOULD RADIATE WARMER TEMPS TOWARD THE SURFACE BY FRIDAY MORNING. THIS WILL BE SOMETHING TO KEEP AN EYE ON IN CASE SURFACE TEMPS ARE 5-10 COLDER THAN CURRENTLY FORECAST. OTHERWISE...DRY WX WITH MODERATING TEMPS FOR SUN-TUE AS MOIST/SOUTHERLY FLOW RETURNS. TR/92 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 59 62 26 41 / 40 60 10 10 WACO, TX 62 66 30 44 / 20 40 20 10 PARIS, TX 52 61 23 39 / 40 70 20 10 DENTON, TX 50 53 25 40 / 50 60 10 10 MCKINNEY, TX 55 60 24 40 / 40 70 10 10 DALLAS, TX 59 63 26 41 / 40 60 10 10 TERRELL, TX 61 66 26 42 / 30 70 20 10 CORSICANA, TX 62 68 30 43 / 20 50 30 10 TEMPLE, TX 63 67 32 46 / 20 40 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... TX...NONE. && $$ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 331 PM CST TUE JAN 4 2005 .SHORT TERM... A COLD FRONT STALLED ACROSS THE BIG COUNTRY HAS BEEN A TRICKY FORECAST ISSUE EVEN IN THE SHORT TERM. THIS MORNING IT LOOKED LIKE WITH THE COLD AIR THAT THE FRONT WOULD NOT MOVE MUCH...BUT THE FRONT SLOWLY EDGED NORTH INTO THE NORTHERN BIG COUNTRY COUNTIES. THE FRONT IS NOT EXPECTED TO MOVE MUCH ONCE THE SUN SETS. ALOFT... STRONG SW UPPER FLOW CONTINUES WITH A STRONG UPPER JET PUSHING THROUGH THE BAJA TOWARDS EL PASO AS SEEN IN WATER VAPOR IMAGES. THIS JET STREAK SHOULD MOVE INTO W TX EARLY TONIGHT WITH THE MAIN TROUGH MOVING INTO THE PLAINS WEDNESDAY MORNING. THE MAIN FORECAST QUESTIONS DEPEND ON THE POSITION OF THE FRONT OVER THE BIG COUNTRY AND THE SURGE OF ARCTIC AIR WEDNESDAY MORNING. LATEST RUC AND MESO ETA MODEL RUNS HAVE A GOOD HANDLE ON THE SFC FEATURES AND TEMPS. GFS HAS BEEN WAY OFF ON TEMPS AND CANNOT RESOLVE THE SHALLOW COLD AIR IN PLACE. STICKING WITH THE RUC AND MESO ETA WHICH ARE RESOLVING THE COLD AIR MASS IN PLACE AND THE SURGING ARCTIC AIR IN THE CENTRAL PLAINS...THE FRONT OVER THE BIG COUNTRY SHOULD NOT MOVE MUCH TONIGHT. THE FRONT SHOULD BEGIN THE MAKE SOME PROGRESS SOUTH WED MORNING AS THE ARCTIC AIR MEETS THE STALLED FRONT AND IT SHOULD PUSH THROUGH MUCH OF W CENTRAL TX BY 18Z WED. IT IS POSSIBLE THAT THE FRONT COULD PUSH THROUGH EARLIER THAN PROGGED GIVEN THERE IS NOTHING TO STOP THE ARCTIC AIR AND IT IS NOT FAR AWAY AS IT HAS ALREADY PUSHED INTO CENTRAL KS. WITH THAT...TEMPS SHOULD SLOWLY DROP THROUGH THE DAY WED WITH THE BIG COUNTRY NOT WARMING UP MUCH AT ALL. PRECIP CHANCES ARE ALSO AN ISSUE. WATER VAPOR IMAGES SHOW DRIER AIR WORKING INTO THE REGION ALOFT. THERE WILL BE SOME STRONG DYNAMICAL FORCING WITH THE JET STREAK TONIGHT SO CHANCE POPS ARE LEFT FOR THE BIG COUNTRY WITH LOWER POPS FOR THE CONCHO VALLEY SOUTHWARD. WEDNESDAY IS TRICKY AS WELL AS THE MESO ETA KEEPS MOST OF THE PRECIP AND FRONTAL FORCING EAST OF OUR FORECAST AREA. SOME POPS ARE LEFT IN THE FORECAST FOR WEDNESDAY MAINLY FOR THE BIG COUNTRY AND HEARTLAND WITH THE FRONTAL FORCING. AFTER THE FRONT...HIGH PRESSURE BUILDS IN THE REGION WHICH WILL PUT A CAP ON PRECIP CHANCES. && .LONG TERM... THURSDAY THROUGH THE WEEKEND LOOKS LIKE THE UPPER FLOW BECOMES MORE ZONAL WITH SOME TROUGHING OCCURRING OVER THE PACIFIC SATURDAY AND SUNDAY. DRY CONDITIONS ARE EXPECTED ALTHOUGH THE GFS DOES GENERATE SOME PRECIP OVER THE HILL COUNTRY WITH WAA AND THE DEVELOPMENT OF A GULF LOW IN S TX. RIGHT NOW THINK THAT MOST OF THE PRECIP WILL STAY SOUTH OF THE AREA AND QUICKLY MOVE EAST. DRIER AIR IS EXPECTED TO PUSH INTO W CENTRAL TX ON SATURDAY WHICH WILL ALSO KEEP ANY POPS TO THE EAST OF THE FORECAST AREA. EARLY NEXT WEEK THE UPPER TROUGH OFF THE WEST COAST BEGINS TO MOVE EAST. THE PATTERN IS SIMILAR TO THIS LAST SYSTEM BUT COULD PULL OUT FARTHER NORTH INTO THE CENTRAL PLAINS. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 44 44 27 43 / 40 30 0 0 SAN ANGELO 60 61 30 48 / 30 20 0 0 JUNCTION 63 65 32 51 / 20 20 10 0 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/10 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 238 PM CST TUE JAN 4 2005 .SHORT TERM... STRONG MID/UPPER LOW NOW CENTERED OVER SOUTHERN CA IS SLOWLY BEGINNING TO MOVE EAST. AN UPPER LEVEL JET MAX OF 130+KT IS CURRENTLY ROTATING AROUND THE SOUTHERN SIDE OF THIS LOW OVER NORTHERN OLD MEXICO...THEN NORTHEAST INTO SOUTHERN NM. THIS SPEED MAX WILL COMBINE WITH GOOD MOISTURE...AND PVA OVER NM TO AID IN THE DEVELOPMENT OF MORE PRECIP OVER SOUTHERN NM. LAPSE RATES WILL DECREASE THROUGHOUT THE NIGHT...BUT WILL START NEAR 6C/KM...SO WE MAY GET SOME TSRA OUT OF THE ACTIVITY EARLY ON...ESPECIALLY CONSIDERING THAT WITH A SIMILAR SET UP LAST NIGHT WE DID GET SOME THUNDER OVER OUR SERN NM COUNTIES. NOT EXPECTING CONVECTION IN NM TO REACH SEVERE LIMITS HOWEVER. IF CONVECTION CAN HOLD TOGETHER AND MAKE IT INTO EASTERN AREAS...LAPSE RATES AND INSTABILITY INCREASE... THUNDERSTORMS COULD BECOME STRONGER...BUT STILL NOT EXPECTING STORMS TO BECOME SEVERE. WILL KEEP HIGHEST POPS OVER SERN NM...AND THE NORTHERN COUNTIES OF THE CWA...SINCE THESE AREAS WILL BE CLOSEST TO MID AND UPPER LEVEL DYNAMICS OF THIS SYSTEM. AT THE SURFACE...THE COLD FRONT HAD LIFTED BACK NORTH OF BIG SPRING BY 17Z. COULD SEE THE EDGE OF THE FRONT AT 1930Z USING VIS IMAGERY AS A LINE OF LOW CLOUDS EXTENDS ROUGHLY WEST TO EAST FROM ANDREWS COUNTY...THEN ACROSS THE NORTHERN PORTIONS OF MARTIN...HOWARD AND MITCHELL COUNTIES. WILL WEIGHT FORECAST FOR TONIGHT TOWARD THE RUC SOLUTION OF THIS BOUNDARY...AS THE ETA AND GFS HAVE NOT HAD A LOT OF SUCCESS RESOLVING IT. WILL KEEP THE COLD AIR IN PLACE ACROSS THE NORTHEASTERN COUNTIES OF OUR CWA. A PACIFIC FRONT IS ALSO EXPECTED TO MOVE IN FROM THE WEST FOLLOWING THE PRECIP. WEST WINDS AND LOWER DEWPOINTS WILL MAKE THEIR WAY INTO THE SOUTHEASTERN NM PLAINS BY 12Z TOMORROW MORNING. && .LONG TERM... OVERALL...MODELS LOOK TO BE WELL INITIALIZED THIS MORNING. WE'RE LOCKED INTO A NEGATIVE PNA PATTERN WITH VERY STRONG POSITIVE HEIGHT ANOMALIES OVER THE NORTHERN PACIFIC AND LESSER...BUT ABOVE NORMAL... HEIGHT ANOMALIES OVER THE EASTERN CONUS...AND THIS PATTERN IS FORECAST TO CONTINUE THROUGH AT LEAST EARLY NEXT WEEK. THE ETA IS THE FARTHEST SOUTH WITH RESPECT TO THE COLD FRONT THAT PUSHES INTO THE NORTHEASTERN CWFA WEDNESDAY...FITTING OUR CONCEPTUAL MODEL ON HOW COLD FRONTS BEHAVE HEREABOUTS...AND WE WILL TREND HEAVILY TOWARD ITS SOLUTION WEDNESDAY AND THURSDAY. BY FRIDAY...THE OPERATIONAL GFS APPEARS TO TRACK WITHIN THE GFS ENSEMBLE MEANS AS WELL AS THE SOLUTIONS OFFERED BY THE GEM AND ECMWF...THUS WE WILL TREND TOWARD ITS SOLUTION THROUGH EARLY NEXT WEEK. BY THE BEGINNING OF THE LONG TERM PERIOD...PRECIP WILL BE ENDING ACROSS THE NORTHEASTERN CWFA AS LIFT ASSOCIATED WITH THE EXITING SHORTWAVE TROUGH TRANSLATES AWAY FROM THE REGION. IN ITS WAKE... MODIFIED ARCTIC AIR WILL WORK ITS WAY INTO THE NORTHEASTERN CWFA WEDNESDAY. THIS FRONT SHOULD MAKE IT AS FAR AS THE PECOS RIVER VALLEY THURSDAY NIGHT BEFORE BECOMING STATIONARY. MARKED COOLING IS NOTED AT 850 hPa AS TEMPERATURES FALL BELOW 5C ACROSS THE WESTERN LOW ROLLING PLAINS. THIS ALONG WITH CONTINUED CLOUDINESS AND MODEST LOW LEVEL COLD AIR ADVECTION WILL KEEP TEMPERATURES BELOW NORMAL OVER THE NORTHEASTERN THIRD OF THE CWFA THURSDAY. BY THURSDAY NIGHT... HOWEVER...HEIGHTS BEGIN FALL OVER THE WESTERN CONUS AS ANOTHER SHORTWAVE TROUGH RELOADS INTO THE MEAN LONGWAVE POSITION. SURFACE CYCLOGENESIS WILL RESUME ALONG THE LEE SLOPES OF THE CENTRAL ROCKIES IN RESPONSE TO INCREASING ZONAL FLOW DOWNSTREAM OF THIS FEATURE... WITH THE END RESULT BEING VEERING OF SURFACE WINDS BACK IN THE COLD AIR AND SUBSEQUENT FRONTOLYSIS ON FRIDAY. INCREASING WESTERLY WINDS AT THE SURFACE ALONG WITH GOOD THICKNESS WARMING WILL LEAD TO A WARMUP BEGINNING FRIDAY...WITH ABOVE NORMAL HIGHS RETURNING TO THE REGION SATURDAY AND CONTINUING INTO THE MIDDLE OF NEXT WEEK. GULF MOISTURE WILL SLOWLY INCREASE ACROSS THE EASTERN HALF OF THE AREA... AMELIORATING LOW TEMPERATURES ACROSS THESE AREAS AS WELL. A SERIES OF SHORTWAVE TROUGHS EMBEDDED IN THE FAST SOUTHWESTERLY FLOW ALOFT WILL TRANSIT THE REGION AS WELL...BUT WITH THE BEST DYNAMICAL LIFT FORECAST TO REMAIN WELL TO THE NORTH...SIG WX NIL THROUGH EARLY NEXT WEEK. HOWEVER...WINDY CONDITIONS MAY BECOME AN ISSUE SUNDAY THROUGH TUESDAY...PARTICULARLY ACROSS THE GUADALUPES WHERE EXTENDED PROGS SUGGEST CONDITIONS FAVORABLE FOR MOUNTAIN WAVE DEVELOPMENT. THE PREVIOUS FORECAST WAS DRY AND WE WILL KEEP IT THAT WAY. WE'VE LOWERED TEMPERATURES WEDNESDAY AND THURSDAY BEHIND THE COLD FRONT BUT NOT QUITE AS MUCH AS INDICATED BY THE LATEST ETA GUIDANCE. WE WILL ATTENUATE THE FORECASTED WARMUP FRIDAY GIVEN THE MODELS' PROPENSITY TO ERODE ARCTIC AIRMASSES TOO FAST...BUT BY SATURDAY...THE PREVIOUS FORECAST LOOKS GOOD WITH ONLY MINOR NUDGES NECESSARY HERE AND THERE. DID INCREASE WINDS THIS WEEKEND INTO EARLY NEXT WEEK...ESPECIALLY ACROSS THE GUADALUPES SUNDAY THROUGH TUESDAY. WE HAVE TRENDED SKY GRIDS STRONGLY TOWARD THE OPERATIONAL GFS SOLUTION AS THIS MODEL TYPICALLY DOES BEST IN DEPICTING UPPER LEVEL SUBTROPICAL MOISTURE FEEDS DURING EASTERN PACIFIC SPLIT FLOW REGIMES. LASTLY...DEWPOINT GRIDS REFLECT A BLEND OF THE OPERATIONAL GFS AND GFS MOS SOLUTIONS. && .PRELIMINARY POINT TEMPS/POPS... BIG SPRING TX 44 58 29 46 / 30 10 0 0 CARLSBAD NM 44 58 29 55 / 40 10 0 0 DRYDEN TX 57 70 40 55 / 10 0 10 0 FORT STOCKTON TX 49 58 36 56 / 20 0 0 0 GUADALUPE PASS TX 37 48 31 52 / 40 0 10 0 HOBBS NM 43 56 25 53 / 40 10 0 0 MARFA TX 40 56 29 59 / 20 0 10 0 MIDLAND INTL AIRPORT TX 48 59 30 48 / 30 10 0 0 ODESSA TX 48 58 29 49 / 30 10 0 0 WINK TX 48 61 31 59 / 30 10 0 0 && .MAF WATCHES/WARNINGS/ADVISORIES... TX...NONE. NM...NONE. && $$ 20/70 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SAN ANGELO TX 1140 AM CST TUE JAN 4 2005 .UPDATE... LATEST RUC CONTINUES TO HOLD THE SURFACE COLD FRONT ACROSS THE SOUTHERN BIG COUNTRY SOUTH OF INTERSTATE 20. RUC SUGGESTS THE THUNDERSTORM POTENTIAL IS LIMITED THIS AFTERNOON. HOWEVER...WITH A LATEST SATELLITE IMAGERY INDICATES SOME CLEARING ACROSS WEST TEXAS WHICH COULD DESTABILIZE OUR AREA. THUS...SENT A QUICK UPDATE TO REMOVE MORNING WORDING AND ADJUST TEMPERATURES FOR THIS AFTERNOON ACROSS THE BIG COUNTRY. OTHERWISE...NO OTHER CHANGES. && .PREV DISCUSSION... THAT IS NEARLY STATIONARY...OR MAYBE MOVING SLOWLY SOUTH JUST TO THE SOUTH OF THE ABILENE AND SWEETWATER AREA. FRONT WILL LIKELY HANG UP ALONG THE HILLS SOUTH OF ABILENE. ANYWAY MODELS ARE STILL NOT HANDLING THIS FRONT AT ANY RATE. THE RUC...WHICH HAS HAD SOME SUCCESS OVER THE PAST 24 HOURS IN INDICATING THE TRENDS TELLS ME THAT THE FRONT WILL BE TOUGHER TO ERODE TODAY THAN PREVIOUSLY THOUGHT. AS A WAVE TRIES TO DEVELOP ON THE FRONT LATTER TODAY...IT MAY TRY TO LIFT TO THE NORTH...HOWEVER THIS MAY BE OFFSET BY CONVECTION THAT WILL MOVE JUST NORTH OF THE FRONTAL BOUNDARY TODAY AS SEEN ON THE RADARS MOVING OUT OF WEST TEXAS. ALSO PRESSURE FALLS OUT OVER WEST TEXAS ARE NOT FORECAST TO BE THAT GREAT EITHER AND ANOTHER REASON TO NOT EXPECT THE FRONT TO ERODE. ALSO THE VWP FROM THE DYX RADAR INDICATES THAT THE DEPTH OF THE FRONT AT THE RADAR SITE IS ABOVE 2KFT. SO WILL BE FORECASTING LITTLE IF ANY MOVEMENT TO THE FRONT THROUGH 18 TO 20 HOURS...AND THEN IT SHOULD GET A GOOD SOUTHWARD PUSH. SO FAR TODAY WILL BE GOING WELL BELOW GUIDANCE VALUES GENERALLY ALONG AND NORTH OF I-20. SOUTH OF THIS LINE NUMBERS CLOSER TO FWC LOOK REASONABLE. IF THE FRONT DOES LIFT TO THE NORTH... THERE COULD BE A SIGNIFICANT BUST POTENTIAL AT ABILENE ON TEMPERATURES. ALSO WILL FORECAST LIKELY POPS ALONG AND NORTH OF THE FRONT TODAY WITH WIDELY SCATTERED TO SCATTERED POPS TO THE SOUTH. LATE TONIGHT AND TOMORROW AS SHORT WAVE PASSES TO THE NORTH OF THE AREA...FRONT WILL GET ANOTHER GOOD PUSH TO THE SOUTH AND TEMPERATURES WILL FALL ACROSS THE AREA DURING THE DAY WEDNESDAY. ALSO COULD SEE SHOWERS ALONG THE FRONT AS IT PUSHES INTO A VERY MOIST AIRMASS. PRECIPITATION SHOULD EXIT THE AREA BY TOMORROW NIGHT... HOWEVER TEMPERATURES WILL RETURN TO THE FREEZING MARK OR BELOW AFTER A WEEK OF WELL ABOVE NORMAL TEMPERATURES. TO ADD A MENTION OF PRECIP IN THE SOUTHEASTERN COUNTIES FRIDAY THROUGH SATURDAY. ALSO LOWERED HIGH TEMPERATURES A TAD...HOWEVER COLD AIR INTRUSION THIS TIME SHOULD BE SHORT LIVED AND A RETURN TO ABOVE NORMAL TEMPERATURES ARE EXPECTED BY FRIDAY. && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/HUBER tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1030 AM CST TUE JAN 4 2005 .UPDATE... SHALLOW COLD FRONT IS NOW RETREATING NORTH AS A WARM FRONT IN RESPONSE TO THE APPROACHING UPPER LEVEL SYSTEM. FRONT IS NORTH OF THE METROPLEX AND WILL CONTINUE TO MOVE SLOWLY NORTH THROUGH THE AFTERNOON. THE RUC HAS DONE AN EXCELLENT JOB WITH THIS BOUNDARY THE PAST TWO DAYS AND HAVE FOLLOWED ITS FORECAST CLOSELY. FRONT WILL BECOME STATIONARY AGAIN THIS EVENING AND MAY NOT MAKE IT OUT THE EXTREME NW CWA. DENSE FOG IS OCCURRING TO THE NORTH OF THE FRONT AND WILL CONTINUE THROUGH THE EARLY AFTERNOON. WE WILL HOLD OFF ON A DENSE FOG ADVISORY DUE TO THE LOCALIZED NATURE OF THE FOG. OVERALL THE FORECAST IS IN GOOD SHAPE. DID REMOVE MENTION OF THUNDER EXCEPT FOR THE NORTH WHERE INSTABILITY IS BETTER. HAVE ADJUSTED POPS MAINLY DOWNWARD AS BEST LIFT WILL BE TO THE NORTH THROUGH TONIGHT...BUT SCATTERED STREAMER SHOWERS BENEATH THE CAP WILL CONTINUE. OTHER ADJUSTMENTS TO GRIDDED ELEMENTS WERE MADE TO FALL INLINE WITH LATEST TRENDS. TR/92 && .PREVIOUS UPDATE... 620 AM IT LOOKS LIKE THE HEAVY RAIN WILL REMAIN TO THE NORTHWEST OF THE FORECAST AREA THIS MORNING...THUS WILL BE SENDING OUT AN UPDATED FORECAST PACKAGE SOON TO CANCEL THE FLOOD WATCH. #58 && .AVIATION... 602 AM CST TUE JAN 4 2005 FRONTAL BOUNDARY JUST SOUTH OF THE METROPLEX WILL MOVE NORTH ACROSS AREA TODAY...WITH WINDS SWITCHING SOUTH LATE MORNING AND CEILINGS RAPIDLY IMPROVING AFTER FROPA. I WAS A BIT SURPRISED THAT VISIBILITIES HAVE NOT DROPPED FARTHER THAN THEY DID BECAUSE JUST NORTH OF A FRONTAL BOUNDARY IS THE IDEAL PLACE FOR DENSER FOG. WACO IS CURRENTLY VFR BUT THERE ARE PLENTY OF MVFR CEILINGS TO THEIR SOUTH AND EXPECT CEILINGS TO DROP SHORTLY...AGAIN IMPROVING DURING THE MORNING. I SEE LITTLE CHANCE FOR THUNDER AT TAF AIRPORTS TODAY BECAUSE ALL ENERGY SEEMS TO BE FARTHER NORTH. CANNOT PINPOINT ANY RAIN WHICH SHOULD BE SPOTTY AT BEST SO HAVE LEFT IT OUT OF TAFS TOO. THE NEXT CHANCE FOR THUNDER SHOULD BE ALONG THE COLD FRONT EXPECTED FOR WEDNESDAY AROUND MID DAY..ALTHOUGH LAPSE RATES LOOK PRETTY MARGINAL ON FORECAST SOUNDINGS. 84 && .DISCUSSION... 405 AM CST TUE JAN 4 2005 A SHALLOW COLD FRONT MOVED TO THE SOUTH OF A PARIS...TO DALLAS...TO ABILENE LINE OVERNIGHT. THIS FRONT HAS BECOME NEARLY STATIONARY AND SHOULD START TO SLOWLY LIFT NORTHWARD LATER TODAY. A SHORTWAVE CURRENTLY OVER SOUTHWEST TEXAS IS PROGGED TO SLIDE NORTHEAST ACROSS THE WESTERN SECTIONS OF NORTH TEXAS...AND THEN INTO NORTHEASTERN OKLAHOMA TODAY. THE BEST LIFT...AND THE BEST POPS WILL BE NORTH OF THE FRONT. AREAS FARTHER SOUTH MAY STILL SEE SOME SHOWERS AND THUNDERSTORMS SO HAVE TAPERED POPS DOWN TO 20S AND 30S ACROSS THE SOUTH CENTRAL AND SOUTHEAST. THE 00Z KFWD SOUNDING SHOWED A PRECIPITABLE WATER VALUE OF 1.65 INCHES WHICH IS OVER 300 PERCENT OF NORMAL. GIVEN THESE FACTORS AND THE WET GROUND FROM THE RAIN THAT WE/VE RECEIVED DURING THE LAST COUPLE OF DAYS...WILL CONTINUE TO FLOOD WATCH THROUGH NOON ACROSS THE NORTH...GENERALLY ALONG AND NORTH OF AN EASTLAND...TO DALLAS...TO SULPHUR SPRINGS LINE. AS THE UPPER TROUGH...CURRENTLY ALONG THE CALIFORNIA COAST LIFTS OUT INTO THE NORTHERN PLAINS ON WEDNESDAY....THE COLD FRONT WILL MOVE THROUGH THE NORTHWESTERN SECTIONS OF NORTH TEXAS LATE TONIGHT...AND THROUGH THE REST OF THE REGION DURING THE DAY WEDNESDAY. MUCH COLDER AIR WILL FILTER IN BEHIND THE FRONT. THE SURFACE RIDGE WILL SLIDE ACROSS NORTH TEXAS THURSDAY...AND THEN TO THE EAST THURSDAY NIGHT...ALLOWING WINDS TO RETURN TO THE SOUTH. THE FORECAST FOR THURSDAY NIGHT/FRIDAY MORNING MAY BE INTERESTING...AS WARM ADVECTION MAY RESULT IN SOME LIGHT PRECIPITATION DEVELOPING ACROSS THE CENTRAL AND EASTERN ZONES. THE ETA IS MORE AGGRESSIVE IN DEVELOPING PRECIPITATION IN THE NORTH CENTRAL AND NORTHEAST ZONES...WHERE TEMPERATURES WILL BE NEAR OR BELOW FREEZING. HAVE OPTED TO JUST LEAVE 10 PERCENT POPS IN THIS AREA FOR NOW...BUT WE WILL HAVE TO KEEP AN EYE ON THIS. TEMPERATURES WILL MODERATE FRIDAY AFTERNOON...AHEAD OF A PACIFIC COLD FRONT THAT WILL MOVE THROUGH NORTH TEXAS SATURDAY. #58 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 69 59 61 30 / 50 50 50 10 WACO, TX 73 63 67 36 / 30 30 40 20 PARIS, TX 69 59 62 30 / 60 50 60 20 DENTON, TX 66 54 53 28 / 70 50 60 10 MCKINNEY, TX 68 59 60 29 / 50 50 60 10 DALLAS, TX 70 60 62 30 / 50 40 50 10 TERRELL, TX 71 62 65 33 / 40 40 50 20 CORSICANA, TX 72 63 67 36 / 40 40 50 30 TEMPLE, TX 74 63 68 38 / 30 20 40 20 && .FWD WATCHES/WARNINGS/ADVISORIES... TX...NONE. && $$ 58 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 954 AM CST TUE JAN 4 2005 .UPDATE... COLD FRONTAL BOUNDARY EXTENDING SOUTHEASTWARD ROUGHLY FROM TATUM NM...THROUGH SEMINOLE...TO BIG SPRING ACROSS OUR CWA HAS NOT BUDGED THIS MORNING. MODELS CONTINUE TO SHOW THIS BOUNDARY LIFTING TO THE NORTH THIS AFTERNOON...WARMING OUR WESTERN LOW ROLLING PLAINS TEMPERATURES UP. HOWEVER...MODELS WERE ALSO TOO FAR NORTH YESTERDAY WITH THE SAME BOUNDARY...SO AM NOT BUYING NORTHWARD MOVEMENT DEPICTED IN ETA AND GFS. RUC...WHICH HAS A BETTER CURRENT HANDLE ON THE SITUATION KEEPS TEMPERATURES RATHER COOL TODAY FOR THE NORTHEASTERN COUNTIES. WILL GO AHEAD AND LOWER HIGH TEMPERATURES OVER THE NORTHEAST...AND ALSO ADJUST WINDS IN THIS AREA. NO OTHER MAJOR CHANGES PLANNED. && .PREVIOUS DISCUSSION... .SHORT TERM... A CUT OFF LOW OVER SOUTHERN CALIFORNIA HAS EJECTED A NUMBER OF SHORTWAVES OUT AHEAD OF IT THAT WILL AFFECT THE AREA TODAY. CURRENTLY A LARGE AREA OF SHOWERS AND THUNDERSTORMS EXTENDS FROM THE UPPER TRANS PECOS ACROSS EASTERN NEW MEXICO TO NEAR THE COLORADO BORDER. A SECOND PRECIP AREA WAS ALSO LOCATED WEST OF ELP AS OF 09Z. PATCHY FOG DEVELOPED ACROSS THE AREA THIS MORNING BUT VISBYS HAVE NOT BEEN TOO BAD. HAVE KEPT THE CHANCE TO LIKELY POPS INHERITED BUT ADJUSTED COVERAGE SOMEWHAT... THE WEST AND NORTH SHOULD HAVE BEST SHOT AT PRECIP. DECREASING POPS TONIGHT. OTHERWISE CLOUDY SKIES... ABOVE NORMAL TEMPERATURES AND HIGH DEWPOINTS EXPETED ON A SOUTH WIND. MAY GET SOME DRY AIR ADVECTION WEST OVERNIGHT AS A MESO LOW FORMS OVER THE SOUTH PLAINS... REST OF AREA SHOULD STAY JUICY. .LONG TERM... THE UPPER LEVEL TROUGH OVER THE SOUTHWESTERN CONUS WILL FINALLY OPEN UP AND LIFT NORTHEAST INTO THE CENTRAL PLAINS WEDNESDAY. SOME LINGERING LIFT AND MOISTURE AHEAD OF THIS FEATURE WILL STILL PROVIDE A SLIGHT CHANCE OF SHOWERS OVER MAINLY THE NORTHEAST PART OF THE AREA WEDNESDAY MORNING BEFORE THE SYSTEM LIFTS OUT. AS THE WAVE LIFTS NORTHEAST...AN ARCTIC COLD FRONT WILL SLIDE SOUTH INTO THE TEXAS PANHANDLE...AND WILL TRY TO BACK DOOR INTO THE EASTERN SOUTH PLAINS. THE WIND AND TEMPERATURE FORECAST FOR THE PERMIAN BASIN AND LOW ROLLING PLAINS WILL BE TRICKY. MODELS SHOW THAT STRONG SURFACE RIDGING WILL BE ORIENTED FROM THE NORTHERN TEXAS PANHANDLE INTO THE RED RIVER VALLEY. THE COLD AIR MAY ACTUALLY TRY TO SLIP FARTHER SOUTH AND WEST THAN MODELS ACTUALLY INDICATE. FOR NOW...HAVE GONE JUST A LITTLE BELOW GUIDANCE NUMBERS FOR WEDNESDAY...WITH TEMPERATURES GENERALLY STAYING NEAR NORMAL. TEMPS ACROSS THE NORTHEAST MAY ACTUALLY NEED TO BE ADJUSTED QUITE A BIT DOWNWARD IF THE COLD AIR SETTLES IN FARTHER SOUTH THAN ANTICIPATED. THE HIGH PRESSURE RIDGE WILL SLIDE EAST TOWARD THE ARKLATEX REGION THURSDAY...WITH A SURFACE TROUGH BECOMING RE-ESTABLISHED OVER THE TEXAS PANHANDLE AND NORTHEAST NEW MEXICO. TEMPS WILL STILL REMAIN NEAR NORMAL. WARMER TEMPERATURES WILL RETURN FRIDAY AS THERMAL RIDGING BECOMES ENHANCED ALONG A MORE WELL DEFINED SURFACE TROUGH ACROSS EASTERN NEW MEXICO AND SOUTHWEST TEXAS. THE NEXT UPPER LOW WILL MOVE INTO CALIFORNIA THURSDAY NIGHT...AND WILL QUICKLY OPEN UP AND LIFT NORTHEAST INTO THE CENTRAL PLAINS FRIDAY NIGHT AND SATURDAY. THE DYNAMICS WITH THIS SYSTEM WILL BE WEAKER AND FARTHER NORTH...SO NO PRECIP IS EXPECTED. DRY WEATHER IS ANTICIPATED SUNDAY AS WEAK MID LEVEL RIDGING BUILDS OVER WEST TEXAS. NO CHANGES WERE MADE TO THE EXTENDED. && .PRELIMINARY POINT TEMPS/POPS... BIG SPRING TX 72 50 56 28 / 40 30 20 0 CARLSBAD NM 63 44 57 32 / 60 40 10 0 DRYDEN TX 70 57 65 41 / 20 20 0 0 FORT STOCKTON TX 72 49 59 38 / 40 20 10 0 GUADALUPE PASS TX 59 37 49 32 / 60 40 10 0 HOBBS NM 63 43 58 30 / 50 30 10 0 MARFA TX 67 40 55 29 / 30 20 0 0 MIDLAND INTL AIRPORT TX 66 48 57 30 / 40 30 10 0 ODESSA TX 66 48 58 30 / 40 30 10 0 WINK TX 73 48 62 33 / 50 30 10 0 && .MAF WATCHES/WARNINGS/ADVISORIES... TX...NONE. NM...NONE. && $$ 72/21 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1218 AM EST WED JAN 5 2005 .AVIATION... NOT A WHOLE LOT OF CHANGES FROM PREVIOUS THINKING. WITH LOTS OF LOW MOISTURE...INCREASING SOMEWHAT LAST EVENING...AM CONTINUING THE IDEA OF GENERAL IFR CEILINGS EVOLVING THROUGH THE EARLY MORNING HOURS...THEN PERSISTING DTW/DET TAF SITES REST OF FORECAST PERIOD WHILE IN THE FNT/MBS TAFS...LESS ROBUST DEEP MOISTURE WILL IMPROVE CEILINGS TO MVFR FOR WEDNESDAY BUT BACK DOWN TO IFR CEILINGS WEDNESDAY EVENING. AS FOR VISIBILITIES...INCREASINGLY LOW VISIBILITIES OVERNIGHT IN SNOW MAINLY DTW/DET...WITH MAIN AREA OF PRECIPITATION ADVANCING IN FROM THE SOUTH...THEN A BIT HIGHER UNTIL DYNAMICS AHEAD OF EJECTING LOW FROM THE SOUTHWEST KICK IN WEDNESDAY AFTERNOON...AND EVEN LOWER VISIBILITIES IN SNOW WEDNESDAY EVENING...INTO LIFR CATEGORY...LOWEST SOUTH. && .UPDATE...ISSUED 857 PM EST TUESDAY CURRENT FORECAST PACKAGE IS GENERALLY DOING VERY WELL. BASED ON LATEST RUC AND CURRENT RADAR TRENDS OF PRECIPITATION APPROACHING FROM THE SOUTH AND WEST...WILL JUST SLIDE BACK ONSET OF SNOW MENTION A COUPLE OF HOURS...TO ABOUT 05Z. OTHERWISE NO CHANGES. && .SHORT TERM...TONIGHT AND WEDNESDAY...ISSUED 430 PM EST TUESDAY LOW PRESSURE SYSTEM WILL DEEPEN OVER SOUTHERN MISSOURI AND WILL BEGIN TO TRACK TOWARDS CENTRAL OHIO AS A STRONG CLOSED LOW OVER SOUTHERN CALIFORNIA PROGRESSES EASTWARD. THIS LOW PRESSURE SYSTEM WILL IMPACT SOUTHERN MICHIGAN OVERNIGHT WITH AN INITIAL BURST OF SNOW...WITH MORE SNOW EXPECTED ACROSS THE AREA WEDNESDAY AFTERNOON THROUGH MIDDAY ON THURSDAY. WINTER STORM WARNING WILL BE OUT SOON FOR COUNTIES ALONG AND SOUTH OF I-94 WITH WATCHES FOR TOMORROW EXTENDING NORTH TO I-69 PLUS SANILAC COUNTY. LOW LEVEL JET WILL MOVE UP THE OHIO RIVER VALLEY OVERNIGHT... TRANSPORTING GOOD MOISTURE TO ITS NORTH AND TIGHTENING THE BAROCLINIC ZONE FROM ILLINOIS TO OHIO. THE FORECAST QUESTION FOR TONIGHT IS IF ENOUGH MOISTURE WILL BE IN PLACE FOR A FEW INCHES OF SNOW OVER OUR SOUTHERN COUNTIES BY MORNING. MODELS SHOWING GOOD MID LEVEL FRONTOGENETICAL FORCING ALONG AND SOUTH OF THE MICHIGAN BORDER TONIGHT WITH THE BEST OMEGA PASSING OVER NORTHERN INDIANA AND OHIO BY 12Z. ETA12 INDICATING OVER .60 QPF BY 18Z WEDNESDAY IN LENAWEE AND MONROE COUNTIES SO WILL GO AHEAD WITH THE WINTER STORM WARNING FOR 4 SOUTHERN MOST COUNTIES IN CWA STARTING TONIGHT. LIMITING FACTOR MAY BE MOISTURE WITH DRY NORTHEASTERLY FLOW SNEAKING IN FROM THE NORTH. THIS SHOULD PROVIDE A SHARP BOUNDARY PREVENTING THE SNOWFALL FROM SPREADING FURTHER NORTH OVERNIGHT. HAVE UNDERCUT ETA NUMBERS A LITTLE WITH CONCERN ABOUT INTRUSION OF DRY AIR AND SOME QUESTION ABOUT MID LEVEL FGEN WEAKENING. OTHERWISE EXPECT SOME SNOW TO BE ON THE GROUND BY SUNRISE ON WEDNESDAY...MAINLY SOUTH OF I-94. MODELS HAVE SPED UP THE TIME FRAME ON THE PERIOD OF BEST LIFT INDICATING THAT MOST OF THE SNOW WILL FALL BETWEEN MIDNIGHT AND DAWN...WITH SOME SNOW CONTINUING ON INTO THE MORNING COMMUTE. SNOW WILL TAPER OFF BY MID MORNING BUT WILL NOT BE FINISHED FOR THE DAY. THIS INITIAL PERIOD OF SNOW PRECEDES A PERIOD OF HEAVIER SNOW AREA WIDE EXPECTED WEDNESDAY AFTERNOON AND NIGHT. AS THE SURFACE LOW APPROACHES...GOOD DYNAMICS WILL SUPPORT SIGNIFICANT SNOWFALL. WE REMAIN UNDER GOOD JET COUPLING WITH UPPER LEVEL DIVERGENCE OVERHEAD AS THE 500MB TROUGH APPROACHES. && .LONG TERM...WEDNESDAY EVENING THROUGH FRIDAY...ISSUED 430 PM EST TUESDAY THE WINTER STORM WILL BE IN FULL SWING OVER SE MICHIGAN HEADING INTO WEDNESDAY NIGHT. IT IS AT THIS POINT THAT WE TRANSITION FROM ALL SNOW OVER THE ENTIRE AREA TO HEAVY SNOW OVER CENTRAL SECTIONS AND SIGNIFICANT MIXED PRECIP NEAR THE OHIO BORDER. THERE IS GOOD MODEL AGREEMENT ON A TRACK OF THE SURFACE LOW THROUGH SOUTHERN INDIANA AND SOUTHERN OHIO, GENERALLY ALONG OR JUST SOUTH OF A LINE FROM IND TO CLE. THERE IS ALSO GOOD AGREEMENT ON A FAIRLY BROAD INVERTED TROF ON THE NW FLANK OF THE SURFACE LOW, WHICH IS A RESULT OF THE NEGATIVE/WESTWARD TILT IN THE SYSTEM THROUGH THE LOW AND MID LEVELS. THIS ASPECT OF THE LOW, ALONG WITH A CLOSED MID LEVEL CIRCULATION, WILL MAKE HEAVY SNOW AND MIXED PRECIP A PROBLEM AROUND DETROIT TO THE OHIO BORDER AND ALL HEAVY SNOW MORE PROBABLE THROUGH CENTRAL SECTIONS OF SE MICHIGAN. SNOWFALL ACCUMULATION, AND THE IMPACT ON IT BY MIXED PRECIP, WILL CONTINUE TO BE UNDER CONSTRUCTION BUT SOME PRECISION IS BECOMING POSSIBLE WITH FAIRLY CONSISTENT MODEL SOLUTIONS. MODEL FORECAST SOUNDINGS AND CROSS SECTIONS FROM THE ETA SHOW AN INTRUSION OF WARM AIR INTO SOUTH SECTIONS OF OUR AREA DURING THE EVENING. THIS IS SHOWN IN CROSS SECTIONS OF WET BULB TEMPERATURE AND THICKNESS FORECASTS FOR THE 850 TO 700 MB LAYER, WHILE 1000-850 MB THICKNESS SAYS SNOW THROUGHOUT THE EVENT. THE GFS IS COLDER AND SHOWS A CLEAR COLDER RESPONSE IN THE MID LEVEL THICKNESS FIELD, SUGGESTING ALL SNOW, AS HEAVIER PRECIP RATES MOVE INTO THE AREA. ON THE OTHER HAND, THE NEGATIVE/WESTWARD TILT TO THE SYSTEM IN ALL OF THE MODELS SUGGESTS THE POTENTIAL FOR AT LEAST SOME WARM AIR TO WORK THROUGH THE LOW LEVELS, ESPECIALLY LATER IN THE EVENING AS PRECIP RATES SLOW DOWN. EXPECT BOTH PRECIP RATE AND THE VERTICAL STRUCTURE OF THE SYSTEM TO PLAY A ROLE AND WILL MAINTAIN MIXED PRECIP AROUND AND SOUTH OF DETROIT, PROBABLY MORE SLEET THAN FREEZING RAIN AND ENOUGH TO CUT INTO SNOW ACCUMULATION, MUCH LIKE IN OUR GOING FORECAST GRIDS. THE SWATH OF HEAVIEST SNOWFALL WILL SET UP ALONG THE AXIS OF THE TROWAL AROUND 700 MB. THE 12Z MODELS SHOW THIS SETTING UP ROUGHLY THROUGH THE I 69 CORRIDOR AS THE SYSTEM OCCLUDES TOWARD MIDNIGHT WEDNESDAY NIGHT. OCCLUSION DYNAMIC FORCING AND LOW STATIC STABILITY WILL LIKELY GENERATE A STRONG VERTICAL MOTION RESPONSE IN THIS AREA DURING THE LATE EVENING AND OVERNIGHT HOURS. SPECIFIC HUMIDITY AROUND 3 G/KG FOR ABOUT AN 18 HR PERIOD MATCHES UP PRETTY WELL WITH MODEL QPF. TOTAL SNOW ACCUMS IN THE 6 TO 10 INCH RANGE ARE ON TARGET IN THE WATCH AREA, WITH LOCAL ACCUMS NEAR 12 INCHES POSSIBLE. THE DRY SLOT WILL CUT OFF THE SNOW QUICKLY AROUND 12Z THURSDAY. THE DRY AIR IN THE MID LEVELS, COMBINED WITH SURFACE CONVERGENCE IN THE LOW LEVEL CYCLONIC FLOW, WILL BRING SOME FREEZING DRIZZLE INTO THE PICTURE THURSDAY MORNING. THE TRI CITIES AND THUMB WILL CONTINUE WITH GENERALLY LIGHT SNOW FORCED BY THE MID LEVEL DEFORMATION ZONE, BUT WITH SOME ACCUMULATION POTENTIAL. GENEROUS QPF IN THE MODELS IS THE RESULT OF A WELL-ORGANIZED MOIST CONVEYOR FROM THE LOW AND MID LEVEL OCCLUSION. THURSDAY ACCUMS IN THE 1 TO 3 INCH RANGE AROUND THE TRI CITIES AND THUMB WILL KEEP THAT AREA JUST UNDER WARNING CRITERIA SNOWFALL FOR THE WEDNESDAY NIGHT AND THURSDAY 24 HOUR PERIOD, BUT WE'LL HAVE TO KEEP AN EYE ON THAT AND ANY LAKE CONTRIBUTIONS THAT COULD BOOST THE TOTALS. THIS SYSTEM WILL LEAVE BEHIND A DRY AND FLAT PATTERN ON FRIDAY AS HEIGHT FALLS RELOAD THE BLOCKING UPPER AIR PATTERN OVER THE EASTERN PACIFIC AND WEST COAST. BROAD SW FLOW ALOFT AND HIGH PRESSURE ALONG THE EAST COAST WILL KEEP TEMPERATURES NEAR 30 FOR HIGHS WITH LOWS AROUND 20. TEMPERATURE GUIDANCE LOOKS PRETTY GOOD FOR THIS TIME PERIOD. && .LONG TERM...SATURDAY THROUGH TUESDAY...ISSUED 430 PM EST TUESDAY THE BLOCKING PATTERN IN THE PACIFIC WILL CONTINUE INTO THE EARLY NEXT WEEK. THIS WILL RESULT IN PERSISTENT TROUGHING ACROSS THE WEST COAST AND BROAD SOUTHWEST FLOW ACROSS THE CENTRAL AND EASTERN US... MAINTAINING RELATIVELY MILD WEATHER ACROSS SE MICHIGAN. THE LATEST TRENDS IN THE MODELS HAVE BEEN A BIT STRONGER WITH HIGH PRESSURE OVER SOUTHERN CANADA... WHICH SLOWS THE WARMING A LITTLE BIT. WILL BACK OFF ON HIGHS ON SATURDAY DUE TO THIS TREND... BUT CONTINUE WITH HIGHS NEAR 40 SUN THROUGH TUE. THE GFS/DGEX/WRFXX HAVE BEEN CONSISTENT IN BRINGING A WEAK SHORT WAVE THROUGH THE REGION SAT/SAT NIGHT... SO WILL CONTINUE WITH A CHANCE OF LIGHT RAIN/SNOW. THE GFS HAS BEEN FAIRLY CONSISTENT SHOWING A POLAR VORTEX DROPPING INTO CENTRAL CANADA BY MID WEEK... THEN PHASING WITH THE SOUTHERN STREAM TROUGH OFF THE WEST COAST... LEADING TO A FULL LATITUDE TROUGH OVER THE CENTRAL US BY THE END OF THE WEEK. THIS IDEA WOULD BRING ANOTHER STRONG STORM SYSTEM IN THE CENTRAL US TUES INTO WED. AT THIS POINT... SE MICHIGAN APPEARS TO BE ON THE WARM SIDE OF THIS SYSTEM. && .DTX WATCHES/WARNINGS/ADVISORIES... .MI... WINTER STORM WARNING...MIZ075-076-082-083...EARLY WEDNESDAY THROUGH THURSDAY MORNING. WINTER STORM WATCH...MIZ055-060>063-068>070...WEDNESDAY AFTERNOON THROUGH THURSDAY MORNING. .LAKE HURON...SMALL CRAFT ADVISORY...SAGINAW BAY AND THE NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON...WEDNESDAY THROUGH WEDNESDAY NIGHT. .LAKE ST CLAIR...SMALL CRAFT ADVISORY...WEDNESDAY AND WEDNESDAY NIGHT. .MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY...WEDNESDAY AND WEDNESDAY NIGHT. DWD/SC/BT/KEK mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SAN ANGELO TX 1142 PM CST TUE JAN 4 2005 .UPDATE... DESPITE WHAT THE ABI ASOS SAYS...CALLS TO VARIOUS SO'S ACROSS THE BIG COUNTRY STILL INDICATE AT LEAST LOCALLY DENSE FOG ACROSS THE AREA. SHOWERS COMING IN FROM THE WEST SHOULD BREAK THINGS UP ACROSS THE WESTERN COUNTIES OVER THE NEXT SEVERAL HOURS...BUT DENSE FOG ACROSS THE CENTRAL AND EAST MAY PERSIST A LITTLE LONGER. WENT AHEAD AND EXTENDED THE DENSE FOG ADVISORY THROUGH 6 AM. && .PREV DISCUSSION... CALLS AROUND THE AREA SUGGEST THAT FOG HAS DROPPED VISIBILITIES TO AT OR BELOW A QUARTER MILE ACROSS AT LEAST A GOOD PART OF THE BIG COUNTRY NORTH OF THE FRONT. HAVE GONE AHEAD AND ISSUED A DENSE FOG ADVISORY THROUGH MIDNIGHT. SOME HOPE THAT RAIN APPROACHES FROM THE WEST AND BETTER MIXING TAKES PLACE...VISIBILITIES WILL RISE ENOUGH THAT THE ADVISORY CAN BE ALLOWED TO EXPIRE. FORECAST ACROSS THE BIG COUNTRY THIS EVENING CONTINUES TO BE A DIFFICULT PROCESS. COLD FRONT WOBBLED BACK THROUGH THE EAST SIDE OF ABILENE WITHIN THE LAST HOUR...DROPPING TEMPERATURES FROM THE LOWER 70S BACK INTO THE MID 50S AT ABILENE REGIONAL AIRPORT. FRONT HAD APPARENTLY NEVER MADE IT THROUGH THE WEST SIDE OF ABILENE...WHERE THE KDYX OBS STAYED IN THE 50S ALL DAY. SIMILAR TO LAST NIGHT...WARM ADVECTION ABOVE THE FRONTAL SURFACE SHOULD DROP VISIBILITIES AND CEILINGS AS FOG AND DRIZZLE DEVELOP. EXPECT TO REMAIN STATIONARY THROUGH THE EVENING...AND THEN BEGIN TO PUSH SOUTH LATER TONIGHT. FRONT WAS EXPECTED TO PUSH BACK THROUGH LATER TONIGHT ANYWAY...SO CURRENT FORECAST LOWS LOOK GOOD...ALTHOUGH WILL NEED ADJUST HOURLY TRENDS. OUT WEST...AREA OF CONVECTION HAS BLOSOMMED ACROSS THE WESTERN PERMIAN BASIN. ALREADY CARRYING DECENT POPS ACROSS THE BIG COUNTRY AND THIS LOOKS REASONABLE. GIVEN THE DYNAMIC AND CHANGEABLE WEATHER...DO NOT EXPECT THIS TO BE THE LAST UPDATE THIS EVENING. A COLD FRONT STALLED ACROSS THE BIG COUNTRY HAS BEEN A TRICKY FORECAST ISSUE EVEN IN THE SHORT TERM. THIS MORNING IT LOOKED LIKE WITH THE COLD AIR THAT THE FRONT WOULD NOT MOVE MUCH...BUT THE FRONT SLOWLY EDGED NORTH INTO THE NORTHERN BIG COUNTRY COUNTIES. THE FRONT IS NOT EXPECTED TO MOVE MUCH ONCE THE SUN SETS. ALOFT... STRONG SW UPPER FLOW CONTINUES WITH A STRONG UPPER JET PUSHING THROUGH THE BAJA TOWARDS EL PASO AS SEEN IN WATER VAPOR IMAGES. THIS JET STREAK SHOULD MOVE INTO W TX EARLY TONIGHT WITH THE MAIN TROUGH MOVING INTO THE PLAINS WEDNESDAY MORNING. THE MAIN FORECAST QUESTIONS DEPEND ON THE POSITION OF THE FRONT OVER THE BIG COUNTRY AND THE SURGE OF ARCTIC AIR WEDNESDAY MORNING. LATEST RUC AND MESO ETA MODEL RUNS HAVE A GOOD HANDLE ON THE SFC FEATURES AND TEMPS. GFS HAS BEEN WAY OFF ON TEMPS AND CANNOT RESOLVE THE SHALLOW COLD AIR IN PLACE. STICKING WITH THE RUC AND MESO ETA WHICH ARE RESOLVING THE COLD AIR MASS IN PLACE AND THE SURGING ARCTIC AIR IN THE CENTRAL PLAINS...THE FRONT OVER THE BIG COUNTRY SHOULD NOT MOVE MUCH TONIGHT. THE FRONT SHOULD BEGIN THE MAKE SOME PROGRESS SOUTH WED MORNING AS THE ARCTIC AIR MEETS THE STALLED FRONT AND IT SHOULD PUSH THROUGH MUCH OF W CENTRAL TX BY 18Z WED. IT IS POSSIBLE THAT THE FRONT COULD PUSH THROUGH EARLIER THAN PROGGED GIVEN THERE IS NOTHING TO STOP THE ARCTIC AIR AND IT IS NOT FAR AWAY AS IT HAS ALREADY PUSHED INTO CENTRAL KS. WITH THAT...TEMPS SHOULD SLOWLY DROP THROUGH THE DAY WED WITH THE BIG COUNTRY NOT WARMING UP MUCH AT ALL. PRECIP CHANCES ARE ALSO AN ISSUE. WATER VAPOR IMAGES SHOW DRIER AIR WORKING INTO THE REGION ALOFT. THERE WILL BE SOME STRONG DYNAMICAL FORCING WITH THE JET STREAK TONIGHT SO CHANCE POPS ARE LEFT FOR THE BIG COUNTRY WITH LOWER POPS FOR THE CONCHO VALLEY SOUTHWARD. WEDNESDAY IS TRICKY AS WELL AS THE MESO ETA KEEPS MOST OF THE PRECIP AND FRONTAL FORCING EAST OF OUR FORECAST AREA. SOME POPS ARE LEFT IN THE FORECAST FOR WEDNESDAY MAINLY FOR THE BIG COUNTRY AND HEARTLAND WITH THE FRONTAL FORCING. AFTER THE FRONT...HIGH PRESSURE BUILDS IN THE REGION WHICH WILL PUT A CAP ON PRECIP CHANCES. THURSDAY THROUGH THE WEEKEND LOOKS LIKE THE UPPER FLOW BECOMES MORE ZONAL WITH SOME TROUGHING OCCURRING OVER THE PACIFIC SATURDAY AND SUNDAY. DRY CONDITIONS ARE EXPECTED ALTHOUGH THE GFS DOES GENERATE SOME PRECIP OVER THE HILL COUNTRY WITH WAA AND THE DEVELOPMENT OF A GULF LOW IN S TX. RIGHT NOW THINK THAT MOST OF THE PRECIP WILL STAY SOUTH OF THE AREA AND QUICKLY MOVE EAST. DRIER AIR IS EXPECTED TO PUSH INTO W CENTRAL TX ON SATURDAY WHICH WILL ALSO KEEP ANY POPS TO THE EAST OF THE FORECAST AREA. EARLY NEXT WEEK THE UPPER TROUGH OFF THE WEST COAST BEGINS TO MOVE EAST. THE PATTERN IS SIMILAR TO THIS LAST SYSTEM BUT COULD PULL OUT FARTHER NORTH INTO THE CENTRAL PLAINS. && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 07 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 930 AM EST WED JAN 5 2004 .SHORT RANGE UPDATE... AT 14Z SFC FRONT POSITIONED ALONG A LINE FROM S OF KHNB -> JUST N OF KSDF -> JUST N OF KLEX. LIGHT TO MODERATE RAIN SHOWERS CONTINUE NORTH OF THAT LINE, WITH BEST COVERAGE OVER SRN INDIANA. RAINFALL RATES THIS MORNING HAVE NOT BEEN THAT MUCH...ABOUT 0.2" IN 3 HOURS OVER SRN IND, WHICH IS BELOW FLOOD GUIDANCE (0.8-1.5"). FOLLOWING LATEST RUC, FRONT LOOKS TO REMAIN PRETTY MUCH WHERE IT IS NOW FOR THE REST OF TODAY. PERIODS OF SHOWERS WILL CONTINUE NORTH OF THE FRONT, ALTHOUGH HEAVIER RAINFALL FOR FLOOD WATCH AREA SHOULD HOLD OFF UNTIL AFTER 5 PM OR SO. ALONG AND ESPECIALLY SOUTH OF THE FRONT OVER CENTRAL KENTUCKY, THINK PCPN WILL CONTINUE TO BE SPORADIC AND LIGHT IN NATURE TODAY. MAXIMA OVER SRN KY WILL PROBABLY REACH INTO THE UPPER 60S WITH LITTLE OR NO PCPN. XXV && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 245 PM CST WED JAN 5 2005 .DISCUSSION FOR AFTERNOON GRIDS/ZONES... ...WINTER STORM AND HEAVY SNOW WARNINGS WILL REMAIN IN EFFECT THROUGH TONIGHT... ETA CONTINUES TO BE PERFORMING REASONABLY WELL BASED ON CURRENT WX. MAIN DIFFERENCE FROM YDYS RUNS IS THAT NOW BOTH ETA AND GFS ARE FORMING A CONSOLIDATED AREA OF LO PRES ASSD WITH ONE DISTINCT SHORT WV. INITIALLY WAS A LTL WORRIED ABOUT THIS PLAYING OUT...BUT WATER VAPOR IMAGERY PAST SVRL HRS AS WELL AS RADAR MOSAICS HINT AT THIS FEATURE REALLY STARTING TO EVOLVE. COMMA HEAD DVLPG OVR N CNTRL KS-SERN NE ATTM WITH INFLECTION ON BACK EDGE OF BAROCLINIC CIRRUS BECOMING MORE PRONOUNCED OVR WRN MO...JUST E OF MKC AREA. THIS MEANS THAT ETA SOLN BRINGING ENHANCED AREA OF VERTICAL MOTION THROUGH FA NXT 12 HRS APPEARS ON TRACK. THEREFORE...IT STILL LOOKS LIKE HEAVIER BURST OF PCPN SHOULD MOVE THRU LATER THIS EVENING AS ADVERTIZED...AND LIFT OFF TO NE ARND 09Z. MOST OF FA THEN GETS DRY SLOTTED...XCP ACRS NWRN/N CNTRL IL WHERE SRN EDGE OF COMMA HEAD ENHANCEMENT IS FCST TO MOVE THRU. THIS AREA SHOULD SEE STEADIER MDT SNOW DVLP THIS EVENING...WITH OCNL BURSTS OF HVY SNOW. BASED ON THIS...WILL KEEP FCST SNOW AMTS GOING WITH STORM TOTALS RANGING FROM 8-12 INCHES ARND RFD...TO 4 TO 8 INCHES ACRS METRO CHICAGO...TO AN INCH OF TWO FAR SE COUNTIES. SIG GLAZING WILL CONT MOST OF TNGT OVR E CNTRL IL AND NWRN IN...GENLY ALG AND S OF KANKAKEE RVR. WILL KEEP CHC POPS IN NRN IL INTO ERLY THU AS DEFORMATION ZONE PCPN MAY HANG ON A LTL LONGRT THERE...OTRW JUST A FEW FLRYS WITH COLD ADVECTION. BENIGN PATN THEN TAKES OVR AS LARGE TROF DVLPS AGAIN OVR WRN CONUS OVR WEEKEND...CAUSING ABNORMAL WARMING AGN HEADING INTO NXT WEEK. MERZLOCK && .AVIATION... THE PRESSURE FALLS OVER THE INDIANA AND KENTUCKY BORDER ARE HIGHEST AROUND EVANSVILLE INDIANA AT 18 UTC. THERE ARE LOW VALUES OF STATIC STABILITY OVER KENTUCKY FROM THE RUC ANALYSIS AT 18 UTC. THE ACARS SOUNDING SHOWS AN INVERSION 8898 FT BUT THE ENTIRE TEMPERATURE PLOT IS BELOW FREEZING. THIS SHOWS THAT SNOW WILL BE THE PRECIPITATION THIS AFTERNOON AND TONIGHT. THE ETA MODEL FORECAST PUTS A LOW OVER SOUTHERN INDIANA BY 06 UTC. WITH THE LOW STATIC STABILITY... DIFFERENTIAL VORTICITY ADVECTION AND DIFFERENTIAL TEMPERATURE ADVECTION THAT FORECAST LOOKS GOOD. THAT WILL PLACE THE HEAVY SNOW BAND NEAR ORD AND RFD AIRPORTS. WILL FORECASTS LIFR VISIBILITY TONIGHT FOR MOST OF THE TAFS. THE WIND IS EXPECTED TO CONTINUE TO BE AROUND 15 KNOTS WITH GUSTS TO 25 KNOTS. PRESSURE FALLS INDICATE AN INCREASING PRESSURE GRADIENT AND THAT WILL SUPPORT THE WIND INCREASE. WHW && .LOT...WATCHES/WARNINGS/ADVISORIES... .IL...HEAVY SNOW WARNING NORTHERN CWA. WINTER STORM WARNING SOUTHERN CWA. .IN...WINTER STORM WARNING FOR ALL OF IN CWA. .LK MI...SMALL CARFT ADVISORY THROUGH WEDNESDAY NIGHT $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 1215 PM CST WED JAN 5 2005 .DISCUSSION FOR MORNING GRIDS/ZONES... ...WINTER STORM WARNINGS AND HEAVY SNOW WARNINGS REMAIN IN EFFECT... WILL CONTINUE TO FAVOR THE ETA SOLUTION FOR THIS FORECAST. MAIN DIFFERENCE BETWEEN ETA/GFS CONTINUES TO BE IN LOW LEVEL THERMAL PROGS WITH MID/UPPER LEVEL HEIGHT FIELDS IN GOOD AGREEMENT. GFS LOW LEVEL THERMAL PROFILES STILL SEEM TOO COLD AND WILL TREND TOWARD WARMER ETA. COVERAGE OF RADAR RETURNS HAS DECREASED SOMEWHAT THIS MORNING AS VORT MAX RACING ACROSS CENTRAL ILLINOIS INTO INDIANA HAS PRODUCED SOME HEAVY PRECIP TO OUR SOUTH. ALSO HEADING TOWARD 12Z BEGINNING TO LOSE GOOD COUPLED JET STRUCTURE. REPORTS HAVE GENERALLY RANGED FROM LESS THAN AN INCH TO UP TO 2 INCHES. CONTINUED BROAD ISENTROPIC ASCENT WILL KEEP PERIODS OF SNOW GOING IN THE FORECAST THROUGH THE AFTERNOON. STILL APPEARS MAIN EVENT WILL BE VERY LATE THIS AFTERNOON AND ESPECIALLY THIS EVENING. AS MAIN UPPER LEVEL VORT MAX AND TROP PV ANOMALY APPROACH LATE THIS AFT/EVE...WILL SEE STRONGEST ISENTROPIC LIFT AND MORE FAVORABLE MID LEVEL TEMPS FOR DENDRITIC GROWTH. ALSO FAIRLY TIGHT MID LEVEL BAROCLINIC ZONE SHOULD BE SITUATED NORTH OF MID LEVEL WAVE WITH DECENT MID LEVEL FRONTOGENESIS SETTING UP ACROSS NRN IL/SRN WI. WITH BETTER FORCING PARAMETERS SETTING UP TO THE NORTH WILL TRIM FEW INCHES OFF TOTALS SOUTH OF INTERSTATE 80 BUT WILL CONTINUE TO MENTION ICING CONCERNS ESPECIALLY SOUTH OF A LINE FROM PONTIAC TO RENSSELAER WHERE LOW LEVEL WARM LAYER MAGNITUDE IS FORECASTED TO BE 3 DEG C OR SLIGHTLY GREATER THROUGH THE AFTERNOON AND INTO EARLY PART OF THE EVENING. ANOTHER VORT MAX NOTED IN WV IMAGERY THIS MORNING ACROSS SW MISSOURI WILL MOVE INTO CENTRAL IL THIS MORNING HELPING TO ENHANCE PRECIP BY LATE MORNING. GIVEN HIGHER LOW LEVEL MIXING RATIOS ACROSS THE FAR SOUTHERN CWA AND BETTER UPPER FORCING THIS AFTERNOON...WILL STAY WITH UP TO HALF INCH OF ICE ACCUMULATION ACROSS THIS ZONE. NORTH OF INTERSTATE 80 WILL NOT CHANGE SNOW AMOUNTS ALL THAT MUCH BUT WILL FOCUS ACCUMULATION MORE TOWARD THE EVENING PERIOD WITH STRONGER UPPER FORCING/ISENTROPIC LIFT. GENERALLY LEFT 2 TO 4 INCH ACCUMULATIONS TODAY FOR AREAS IN THE HEAVY SNOW WARNING. AS LOW LEVEL CIRCULATION ORGANIZES LATE THIS AFTERNOON COULD SEE SOME HEAVIER SNOW FALL RATES AFTER 4 PM WITH STRENGTHENING ISENTROPIC LIFT. WITH TENDENCY TOWARD BEST FORCING LATE IN THE EVENT...HAVE EXTENDED WARNINGS TO EXPIRE AT 6 AM CST THURS MORNING. FOR THURS/FRI WENT WITH TEMPS GENERALLY CATEGORY BELOW GUIDANCE AND IN SOME CASES MORE THAN THAT ESPECIALLY WITH MINS ACROSS THE NORTHERN CWA WHERE SINGLE DIGIT LOWS ABOVE ZERO ARE LIKELY THURS NIGHT. VERY FEW OTHER CHANGES MADE OTHER THAN TO ADD CHANCE OF -RA LATE IN PERIOD AS DECENT WARM FRONTAL BOUNDARY SETS UP ACROSS MID MS VALLEY FOR FIRST PART OF NEXT WEEK. NDM && .AVIATION... THE PRESSURE FALLS OVER THE INDIANA AND KENTUCKY BORDER ARE HIGHEST AROUND EVANSVILLE INDIANA AT 18 UTC. THERE ARE LOW VALUES OF STATIC STABILITY OVER KENTUCKY FROM THE RUC ANALYSIS AT 18 UTC. THE ACARS SOUNDING SHOWS AN INVERSION 8898 FT BUT THE ENTIRE TEMPERATURE PLOT IS BELOW FREEZING. THIS SHOWS THAT SNOW WILL BE THE PRECIPITATION THIS AFTERNOON AND TONIGHT. THE ETA MODEL FORECAST PUTS A LOW OVER SOUTHERN INDIANA BY 06 UTC. WITH THE LOW STATIC STABILITY... DIFFERENTIAL VORTICITY ADVECTION AND DIFFERENTIAL TEMPERATURE ADVECTION THAT FORECAST LOOKS GOOD. THAT WILL PLACE THE HEAVY SNOW BAND NEAR ORD AND RFD AIRPORTS. WILL FORECASTS LIFR VISIBILITY TONIGHT FOR MOST OF THE TAFS. THE WIND IS EXPECTED TO CONTINUE TO BE AROUND 15 KNOTS WITH GUSTS TO 25 KNOTS. PRESSURE FALLS INDICATE AN INCREASING PRESSURE GRADIENT AND THAT WILL SUPPORT THE WIND INCREASE. WHW && .LOT...WATCHES/WARNINGS/ADVISORIES... .IL...HEAVY SNOW WARNING NORTHERN CWA. WINTER STORM WARNING SOUTHERN CWA. .IN...WINTER STORM WARNING FOR ALL OF IN CWA. .LK MI...SMALL CARFT ADVISORY THROUGH WEDNESDAY NIGHT $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 254 PM CST WED JAN 5 2005 .DISCUSSION... MAIN FORECAST CONCERNS ARE PRECIP TRENDS AND ADDITIONAL SNOWFALL AMOUNTS TONIGHT. THE ONGOING WINTER STORM IS UNFOLDING PRETTY MUCH AS EXPECTED. CURRENTLY...THE HEAVY SNOW BANDS ARE WANING ACROSS CENTRAL AND NORTHERN IOWA. ANOTHER SURGE OF SNOW AND SLEET IS MOVING NORTH INTO NORTHERN MISSOURI AND FAR SOUTHERN IOWA...WITH THE DEF ZONE SETTING UP FROM CENTRAL KANSAS INTO FAR SOUTHEAST NEBRASKA. EXTRAPOLATING THIS AXIS...IT PLACES THE GENERAL HEAVIER SNOW TONIGHT ALONG AND EITHER SIDE OF AN ATLANTIC-AMES-WATERLOO LINE. AT 12Z...THE GFS AND RUC HAD A BETTER HANDLE ON THE POSITION OF THE UPPER LOW. BOTH SOLUTIONS (WITH THE EXCEPTION OF THE EARLIER 06Z GFS) HAVE CONSISTENTLY BEEN FARTHER NORTH WITH THE HEAVIER SNOW THAT THE ETA...AND THE 18Z ETA IS NOW TRENDING THAT WAY. THE GFS COL AND 600MB TROWAL AREAS ALSO LINED UP NICELY WITH THE HEAVIER QPF. THE CURRENT DEF ZONE EXTRAPOLATION ALSO SUPPORTS THE FARTHER NORTH AXIS OF THE RUC/GFS...AS DOES THE POSITION OF THE NEAR ZERO EPV LINE. OVERALL...EXPECTING MAX STORM TOTAL AMOUNTS OF 12-15 ACROSS PREVIOUSLY MENTIONED AXIS...WITH LESS NORTH AND SOUTH. TRAVEL CONDITIONS WILL AGAIN BE HAZARDOUS TONIGHT...WITH DRIFTING SNOW AN ISSUE DURING THE EVENING. FORCING WILL BE QUITE STRONG AS THE UPPER LOW DEEPENS ACROSS SOUTHERN IOWA. A WILD CARD FOR TONIGHT IS THE POSSIBILITY OF CONVECTIVE SNOW MAINLY ACROSS THE SOUTHEAST...WHERE CROSS SECTIONS INDICATE NEGATIVE EPV AND FOLDING OF THE THETA-E SURFACES. THIS WILL BEAR WATCHING FOR LOCALLY HIGHER SNOWFALL AMOUNTS THIS EVENING. LIGHTER SNOW WILL CONTINUE AFTER MIDNIGHT MAINLY IN THE NORTHEAST COUNTIES...BEFORE ENDING BY MORNING. FOR THURSDAY THROUGH SATURDAY...CONDITIONS WILL BE COLD AND MAINLY DRY. CONTINUED TO UNDERCUT GUIDANCE WITH FRESH SNOW PACK. THERE WILL BE A WEAK FROPA ON FRIDAY WITH LIMITED MOISTURE. ANY APPRECIABLE SNOW ON SATURDAY ALSO LOOKS TO STAY NORTH OF THE STATE. IN THE LATER PERIODS (SUN-WED)...THE ECMWF/GFS ARE DEPICTING A FAIRLY STRONG SYSTEM IN THE TUES/WED TIME FRAME. PRECIP TYPE WILL BE AN ISSUE AND KEPT GRIDS/ZONES PRETTY GENERAL THAT FAR OUT IN THE FORECAST. KEPT TEMPS BELOW MEX MOS GUIDANCE WITH LINGERING SNOW COVER. && .DMX WATCHES/WARNINGS/ADVISORIES...WINTER STORM WARNING ENTIRE CWA THROUGH 6 AM THURSDAY. && $$ KINNEY ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 325 PM CST WED JAN 5 2005 .DISCUSSION... SIGNIFICANT SNOW HAS CREPT ACROSS THE IOWA BORDER INTO OUR FAR SOUTH CENTRAL MN COUNTIES...BUT WE HAVE DECIDED TO HANDLE SITUATION WITH NOWS RATHER THAN RETURN TO HEADLINES. BEST FORCING (FN VECTOR CONVERGENCE ASSOCIATED WITH MID TROP FRONTOGENESIS) DROPS SOUTH OF OUR CWA LATE THIS AFTERNOON ACCORDING TO BOTH META AND RUC. WE HAVE SOME ACCUMULATING SNOW ALONG ARE SOUTHERN AND SOUTHERN TIER OF COUNTIES THROUGH 06Z...HOWEVER ALONG WITH HIGH POPS. TEMPERATURES LOWERED TONIGHT AND THURSDAY...ESPECIALLY ACROSS OUR NORTHERN COUNTIES AND ETA/GFS APPARENTLY ARE NOT PICKING UP ON THE ARCTIC AIR IN PLACE. FOLLOWING THURSDAY...A MODEST WARMUP OCCURS AND WE USED GFS BASED TEMPERATURES TO DESCRIBE THIS IN THE GRIDS. LONGER TERM...SAT NIGHT THROUGH WED CWA STUCK IN WSW UPPR LVL FLOW PATTERN THRU TUE. AS A RESULT WEAK PULSES OF ENERGY AND SCT MOISTURE WILL PASS OVHD DURING PD. HAVE CONTINUED SMALL POPS SAT NIGHT AND MON WHEN BEST CHANCE OF LIGHT PRECIP WILL BE. SAT NIGHT POPS TO CATCH ANY LINGERING PRECIP FROM EXITING SYSTEM SAT. MON SLIGHT CHANCE DUE TO WEAK FROPA. MOISTURE IS LIMITED WITH BOTH FEATURES SO ANY PRECIP WILL BE LIGHT. IN ADDITION...BEST ENERGY DURING THIS TIME PASSING OVER SRN CANADA/FAR N MN. EXPECTING BIGGEST WX FEATURE DURING PD TO BE SCT/BKN CLDS. PATTERN STARTS TO CHANGE TUE NIGHT AS SIG TROF FORMS OVER DAKOTAS. SFC LOW IS SPAWNED OVER KS TUE WHICH PUSHES ACROSS IA WED AND INTO SRN WI THU. SOME MOISTURE IS DRAWN NWARD FROM GULF BY LOW SO THIS SYSTEM WILL HAVE MORE TO WORK WITH. AS LOW PASSES BY TUE NIGHT THRU WED NIGHT...PRECIP IS POSSIBLE CWA WIDE. FOR NOW...BEST LIFT AND QPF PROGGED TO PASS TO OUR S WITH THIS SYSTEM BUT WILL NEED TO WATCH SYSTEM CLOSELY TO MAKE SURE THIS DOESN'T CHANGE. && .MPX WATCHES/WARNINGS/ADVISORIES... .MN...NONE. .WI...NONE. && $$ MARGRAF mn