AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 332 PM MST FRI DEC 21 2007 .SHORT TERM... (TONIGHT AND SATURDAY) ...SNOW ENDING IN WESTERN MOUNTAINS THIS EVENING... ...SNOW AND BLOWING SNOW FOR MUCH OF EASTERN MOUNTAINS AND PLAINS... CURRENTLY...FRONT JUST PASS THROUGH KPUB AT 21Z...WHILE SOUTH OF KPUB THE WEATHER REMAINS BREEZY AND MILD WITH TEMPERATURES IN THE 40S TO 50S NEAR THE MOUNTAINS. SOME LIGHT SNOW HAS BEGUN OVER MONUMENT HILL AS REPORTED BY SPOTTERS AND WEBCAMS. IN THE CENTRAL AND SOUTHWEST MOUNTAINS...WEBCAMS SUGGEST SNOW HAS BECOME LIGHTER. .TONIGHT...COMPACT UPPER LOW SPINNING OVER WESTERN COLORADO WILL CONTINUE TO MOVE SOUTHEAST AND PASS ACROSS CENTRAL NEW MEXICO OVERNIGHT. WITH SOME COOLER CLOUD TOPS MOVING NORTHWARD INTO SOUTHWEST COLORADO...THE ADVISORY FOR THE CENTRAL AND SOUTHWEST MOUNTAINS WILL CONTINUE THROUGH 03Z...AS SCHEDULED. WHILE THE HEAVIEST NOW IS LIKELY OVER...SOME LOCALLY HEAVY SNOW SHOWERS WILL CONTINUE. FOR THE EASTERN MOUNTAINS AND EASTWARD...FORECAST IS CHALLENGING GIVEN THE COMPACT NATURE OF THE SYSTEM. 700MB FLOW OF 20 TO 40 KNOTS WILL DEVELOP DURING THE EVENING AND CONTINUE OVERNIGHT. MAIN QUESTION IS THE ORIENTATION OF THE FLOW FROM 700MB AND BELOW. THE UPPER LOW TRACK LOOKS TO BE FAR ENOUGH SOUTHWEST THAT THE LOWER LEVEL FLOW WILL BE FROM THE NNE TO NE DURING THE EVENING AND GRADUALLY TURN NORTHERLY DURING THE NIGHT. THE FLOW WILL HAVE ENOUGH OF AN EASTERLY COMPONENT TO BRING WARNING CRITERIA SNOW TO THE WET MOUNTAINS AND SOUTHERN SANGRE DE CRISTO MOUNTAINS...AND THE WARNINGS FOR THESE REGIONS HAVE BEEN MAINTAINED. THE BEST OROGRAPHICS WILL OCCUR UNTIL MIDNIGHT WITH 700MB OF 20 TO 40 KNOTS...WITH LIGHTER SNOW OVERNIGHT. TO FURTHER NORTH...PIKES PEAK AND RAMPART RANGE WILL HAVE LESS OROGRAPHICS AND MAINTAINED ADVISORY FOR THESE REGIONS. THE DEEP NORTHERLY FLOW IS ALSO FAVORABLE FOR HEAVY SNOW ALONG THE INTERSTATE 25 CORRIDOR. MODEL QPF GENERALLY SHOW A BAND OF HIGHER AMOUNTS IN THESE REGION...WITH SNOWFALL TOTAL APPROACHING OR EXCEEDING 6 INCHES. WITH THE GUSTY WINDS...HAVE UPGRADED THE ADVISORY TO A WARNING FOR THIS REGION. ON THE PLAINS...WIND...OROGRAPHICS AND SOME DYNAMICS MAKE THE FORECAST MORE COMPLICATED. THE 12Z GFS...SREF AND RUC SUGGEST A FAIRLY NARROW BAND OF FRONTOGENETICAL FORCING ALONG THE NEW MEXICO BORDER DURING THE EVENING. THERE WAS A BAND OF SIGNIFICANT ISENTROPIC UPGLIDE WITH THIS AREA...BUT THIS BAND WAS LESS EVIDENT ON THE 18Z NAM. THIS REGION OF UPGLIDE MAY CREATE A REGION OF HIGHER ACCUMULATIONS. OTHERWISE...MODEL QPF FIELDS SHOW A STRONG OROGRAPHIC INFLUENCE WITH BEST ACCUMULATIONS SOUTH OF THE ARKANSAS RIVER. GUSTY NORTH WINDS WILL ACCOMPANY THE SNOW. THE BUFKIT SOUNDINGS SHOW A REGION OF 40 TO 50 KNOT WINDS ALOFT LOWERING DURING THE NIGHT. IF THESE WINDS WERE TO REACH THE SURFACE...THEN WINDS WILL BE SUFFICIENTLY STRONG FOR BLIZZARD CONDITIONS...IF THERE IS SUFFICIENT SNOWFALL. LOOKING AT THE FORECAST SURFACE PRESSURE GRADIENT AND PROJECTED PATH OF THE SURFACE LOW...THE REALLY STRONG WINDS WILL NOT REACH THE SURFACE. STILL WINDS OF 15 TO 30 MPH WILL CREATE SIGNIFICANT BLOWING AND DRIFTING SNOW...BUT NOT ENOUGH FOR A BLIZZARD HIGHLIGHT. TO GET VERY STRONG WINDS...THERE SHOULD BE A STRONGER AND SLOWER MOVING SURFACE LOW TO THE SOUTH OR EAST. SNOWFALL AMOUNTS WILL APPROACH ADVISORY CRITERIA...BUT THE THREAT FOR SIGNIFICANT BLOWING AND DRIFTING WARRANTS THE ADVISORY. .SATURDAY...SYSTEM MOVES TO EAST WITH CLEARING DURING THE MORNING. SOME SNOW MAY LINGER AFTER 12Z ON THE FAR EASTERN PLAINS. WINDS ALOFT WILL CONTINUE TO BE STRONG...BUT WITH THE SURFACE LOW MOVING EAST...THE SURFACE PRESSURE GRADIENT WILL WEAKEN FOR BREEZY CONDITIONS ON THE PLAINS. AIR ALOFT IS COLD WITH HIGHS STRUGGLING TO APPROACH FREEZING ON THE PLAINS. --PGW-- .LONG TERM... (SUNDAY THROUGH FRIDAY) ...ACTIVE WEATHER PATTERN CONTINUES... ...TEMPERATURES TO REMAIN BELOW AVERAGE THROUGH NEXT WEEK... ...MODERATE IMPACT WEATHER SYSTEM POSSIBLE FOR CHRISTMAS... SUNDAY AND MONDAY...ANOTHER QUICK MOVING UPPER LEVEL DISTURBANCE MOVES THROUGH THE CENTRAL ROCKIES LATE SUNDAY AFTERNOON AND NIGHT...THEN OUT OF CO BY MONDAY. GREATEST CHANCE FOR PRECIPITATION WOULD BE IN THE MOUNTAINS AND HIGH VALLEYS. MOISTURE CONTENT NOT ALL THAT GREAT...BUT WITH RELATIVELY COLD TEMPERATURES FLUFFY 1-4 INCHES WOULD BE POSSIBLE...AGAIN MAINLY IN THE MOUNTAINS/HIGH VALLEYS. MAXIMUM/MINIMUM TEMPERATURES WILL REMAIN BELOW LATE DEC AVERAGES. CHRISTMAS DAY...MODELS CONTINUE TO SUGGEST A LITTLE STRONGER WEATHER SYSTEM FOR LATE CHRISTMAS EVE AND CHRISTMAS DAY. THE WEATHER SYSTEM DROPS INTO THE CENTRAL ROCKIES LATE CHRISTMAS EVE WITH THE POTENTIAL FOR SNOW SPREADING INTO THE CONTINENTAL DIVIDE AND THEN ACROSS ALL OF CO ON CHRISTMAS DAY. THE WEATHER SYSTEM AND ASSOCIATED WEATHER MAY MOVE OUT OF THE CENTRAL ROCKIES BY EARLY WEDNESDAY MORNING. THE 12Z/21 ECMWF IS A LITTLE FURTHER SOUTH WITH THE 500MB LOW TRACK...BUT THERE MIGHT BE ENOUGH ISENTROPIC ASCENT ON THE NORTHERN FRINGE OF THE SYSTEM TO SUPPORT CLOUDS/PRECIPITATION. ASSUMING THE GFS QPF IS CORRECT...THERMAL STRUCTURE(COLD AIR ALOFT) WOULD SUPPORT SNOW RATIOS OF 20-1 WITH VERY FLUFFY SNOW AND APPROXIMATELY 3-8 INCHES IN THE MOUNTAINS/HIGH VALLEYS AND 1-3 INCHES ALONG THE I-25 CORRIDOR AND SOUTHEAST CO PLAINS DURING CHRISTMAS DAY. MIGHT NEED AN ADVISORY FOR CHRISTMAS DAY...JUST FOR THE HIGH TRAVEL DAY...BUT STILL A LONG WAY OFF. TEMPERATURES WILL CONTINUE TO BE BELOW LATE DEC AVERAGES. WEDNESDAY THROUGH FRIDAY...CERTAINLY AN ACTIVE WEATHER PATTERN CONTINUES WITH WEATHER DISTURBANCES MOVING THROUGH THE CENTRAL ROCKIES EVERY OTHER DAY OR SO. TEMPERATURES WILL CONTINUE TO BE BELOW LATE DEC AVERAGES. EACH WEATHER SYSTEM DOES NOT APPEAR TO BE THAT STRONG...JUST NUISANCE...OR VERY LOW IMPACT...WEATHER. METZE && .AVIATION... GUSTY NORTHERLY WINDS WILL CONTINUE THROUGH THE NIGHT OVER THE PLAINS AND EASTERN MOUNTAINS...INCLUDING KPUB AND KCOS. KCOS WILL BE SHADOWED BY NORTHERLY WINDS...AND ANTICIPATE A PERIOD OF SNOW WITH LOWER CEILINGS AND VISIBILITIES. FURTHER TO THE NORTH...EXPECT LOWER CEILINGS AND VISIBILITIES IN THE SNOW. KPUB WILL ALSO BE SHADOWED BY THE NORTHERLY FLOW...WITH LOWER CEILINGS AND VISIBILITIES WITH PERIODS OF SNOW. CONDITIONS WILL BE WORSE TO THE SOUTH AND SOUTHEAST AS WELL AS OVER THE EASTERN MOUNTAINS. KALS MAY GET A PERIOD OF SNOW WITH SOME MVFR CONDITIONS. && .PUB WATCHES/WARNINGS/ADVISORIES... SNOW AND BLOWING SNOW ADVISORY FROM 6 PM THIS EVENING TO 5 AM MST SATURDAY FOR COZ072-073-078-086-093-094-097>099. SNOW AND BLOWING SNOW ADVISORY UNTIL 8 PM MST THIS EVENING FOR COZ058>061-066-068. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 5 AM MST SATURDAY FOR COZ074-075-079-080-087-088. SNOW AND BLOWING SNOW ADVISORY UNTIL 2 AM MST SATURDAY FOR COZ081-082-084. && $$ 06/17 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 408 AM MST FRI DEC 21 2007 .SHORT TERM... (TODAY AND TONIGHT) ...SNOW WILL FLY LATER TODAY INTO TONIGHT MOST AREAS... ...RUSH HOUR ACROSS COS AREA WILL BE AFFECTED THIS AFTERNOON... CURRENTLY...WESTERLY SFC WINDS HAVE KEPT TEMPS UP THIS MORNING AS REASDING MOST AREAS ARE IN THE 30S AND 40S. CLOUDS OVER THE SAN LUIS VALLEY (SLV) HAVE EVEN KEPT TEMPS IN THE TEENS (VS NEGATIVE VALUES OF THE LAST WEEK OR SO). COMPOSITE RADAR ACROSS THE STATE INDICATS SNOW IS ALREADY FALLING OVER NW CO AND ECHOES ARE BEGINNING TO SHOW UP OVER NEW MEXICO. SFC CHART/3H P CHANGE SHOWS FRONT STILL UP IN THE C WY AREA. WATER VAPOR/RUC ANALYSIS FIEDLS SHOW TROUGH AXIS EXTENDING FROM SALT LAKE SSW ACROSS S CALIF. MET DISCUSSION...THE "XMAS HOLIDAY WEEK ACTIVE WX PATTERN" WHICH HAS BEEN ADVERTISED BY THIS WFO THE LAST FEW DAYS WILL BEGIN TODAY. FIRST IN A SERIES OF SYSTEMS STILL ON TRACK TO BRING SNOW TO THE REGION TODAY AND TONIGHT. COMBINATION OF STRONG FRONTOGENETICAL FORCING S OF HIWAY 50 AND STRONG NNE WINDS AT 700 MB SHOULB BRING THE HEAVIEST SNOW ACCUMS ACROSS THE WETS/SANGRE MTN RANGES THEN E TOWARDS THE KS BORDER S OF HIWAY 50. SNOW AND BLOWING SNOW WILL ALSO OCCUR ACROSS THE PALMER DIVIDE...BUT WIND MAY BE THE BIGGEST CONCERN OVER THIS REGION. TODAY (THROUGH 18Z)...TWEAKED POPS A BIT HERE. KEPT VERY HITH POPS ALONG CONTDVD REGION BUT CUT BACK ALL OTEHR AREAS AS I DO NOT THINK WE WILL SEE ANY SIGNIF PRECIP E OF THE CONTDVD UNTIL AFTER 18Z. ALSO...WARMED TEMPS UP A BIT THIS MORNING AS FRONT WILL LIKELY NOT CROSS THE PALMER UNTIL AT LEAST NOONISH. LATER TODAY (AFTER 18Z)...AFTER FRONT CROSSES THE PALMER DVD BELIEVE WINDS WILL PICK UP FROM THE N AND BECOME QUITE GUSTY AND TEMPS WILL BEGIN THERE DOWNWARD TREND. PRECIP WILL LIKELY BEGIN ACROSS TELLER COUNTY BY EARLY AFTERNOON AND REACH DOWN ACROSS N EL PASO BY MID TO LATE AFTERNOON. I DO BELIEVE RUSH HOUR WILL BE AFFECTED BY BLOWING SNOW ACROSS THE GREATER COS AREA...AND HAVE INTRODUCED A SNOW AND BLOWING SNOW ADVISORY FOR TELLER/N EL PASO STARTING A 21Z. ATTM...I AM MORE CONCERNED ABOUT THE BLOWING SNOW THAN THE ACCUMULATING SNOW AS WINDS BY LATER THIS AFTERNOON COULD BE IN THE 20-30 MPH RANGE AS LATEST GUIDANCE IS SHOWING 700 MB WINDS IN THE 40-50 KNOT RANGE. AS FOR THE MTNS...SNOWS WILL BE FLYING ACROSS THE CONTDVD WHERE 3-6" OF NEW SNOW SHOULD FALL BY 00Z. TONIGHT...WINTER STORM WARNINGS ARE IN EFFECT FOR THE WETS AND S SANGRE MTN RANGES. S/BS ADVISORIES ARE IN EFFECT FOR THE PLAINS GENERALLY S OF US HIWAY 50. ADVISORIRES ARE ALSO IN EFFECT FOR THE WET MTN VALLEY AND THE N SANGRES. ADVISORIES ARE ONGOING ACROSS N EL PASO/TELLER. THE HEAVIEST SNOW WITH THIS SYSTEM WILL FALL ACROSS THE E FACING SLOPES OF THE WETS AND S SANGRES. THESE AREAS SHOULD SEE 8-12" OF NEW SNOW BY 12Z TOMORROW. OVER THE PLAINS...THE HEAVIEST SNOWS WILL FALL GENERALLY ALONG THE RATON MESA ALONG THE CO/NM BORDER. SOME OF THESE SNOW TOTAL REACHED INTO THE WARNING CATEGORY BUT DECIDED TO GO WITH A S/BS ADVISORY AS MOST OF THE REGION SHOULD SEE TOTALS IN THE 3-6 RANGE. WINDS WILL ALSO BE A CONCERN ACROSS THIS AREA TONIGHT AND TRAVEL WILL BE DIFFICULT ACROSS RATON PASS AND ALONG HIWAY S OF KLAA. AS ALWAYS WITH THESE NE WIND EVENTS...PUEBLO COUNTY WILL BE PROBLEMATIC. I AM CONFIDENT THAT THE S SXNS OF THE COUNTY WILL SEE S/BS CRITERIA BUT THE N PART OF THE COUNTY (INCLUDING PUB) WILL NOT SEE MUCH. PLAN TO MENTION THIS IN DETAIL IN THE HILITE PACKAGE THAT WILL BE ISSUED SHORTLY. SNOW ACROSS THE PALMER DVD SHOULD START TO WIND DOWN AFTER MIDNIGHT...AND ACROSS THE RATON MESA TOWARDS SUNRISE. /HODANISH .LONG TERM... (SATURDAY THROUGH THURSDAY) ...UNSETTLED WEATHER PROBABLE THROUGH THURSDAY... FORECAST MODELS INDICATE THAT A STRING OF FAST MOVING UPPER LEVEL SYSTEMS WILL BE LINED UP TO AFFECT THE REGION THROUGH THURSDAY. MAXIMUM TEMPERATURES ARE EXPECTED TO REMAIN IN THE 20S AND 30S EACH DAY...THEN DROP INTO THE SINGLE DIGITS TO TEENS EACH NIGHT. THE EXCEPTION WILL BE THE SAN LUIS VALLEY...WHERE LOW TEMPS WILL MOST LIKELY DIP WELL BELOW ZERO EACH NIGHT. SATURDAY...THE FIRST UPPER TROUGH WILL BE EXITING THE REGION SAT MORNING...MAKING FOR AN INITIALLY COLD AND BLUSTERY START ACROSS THE FAR E PLAINS. NW FLOW SETTLES IN...WITH LINGERING POTENTIAL FOR ISOLATED SNOW OVER THE CENTRAL MTS WHILE THE PLAINS CLEAR OUT DURING THE AFTN. SUNDAY AND MONDAY...NEXT SYSTEM DROPS DOWN ACROSS THE N ROCKIES...PRODUCING ISOLATED TO SCATTERED SNOW FOR THE CONTDVD THROUGH THE DAY...THEN SPREADING TO THE ENTIRE CWA BY THE EVENING. BY MON MORNING THIS LOW SHOULD BE MOVING OUT...WITH PCPN TAPERING OFF ACROSS THE SE CORNER. A BREAK IN THE ACTIVE PATTERN IS FORECAST FOR THE REST OF MONDAY...BEFORE THE NEXT SYSTEM DROPS DOWN FOR THE NIGHT. MONDAY NIGHT THROUGH TUESDAY NIGHT...LONG RANGE MODELS ARE INDICATING THAT THE NEXT STORM SYSTEM WILL DROP A BIT FURTHER SOUTH THAN PREVIOUS DISTURBANCES. THIS TRANSLATES TO A GREATER CHANCE OF SNOW FOR THE CONTDVD CHRISTMAS EVE...THEN ALL OF THE FORECAST AREA THROUGH CHRISTMAS DAY. WEDNESDAY AND THURSDAY...LOOKS TO BE A REPEAT OF MONDAY AND TUESDAY. ALL OF THESE SYSTEMS DO NOT LOOK TOO IMPRESSIVE WHEN TALKING ABOUT SNOW AMOUNTS...BUT THE RAPID SUCCESSION INCREASES THE POTENTIAL OF IT FEELING LIKE THE HOLIDAY SEASON THROUGH NEXT WEEK. MOORE && .AVIATION... ALL TAF SITES WILL BE IMPACTED BY THIS WX SYSTEM. FRONT SHOULD CROSS KCOS AROUND 18Z AND KPUB BY 19Z. WINDS WILL SHIFT TO THE N AND BECOME QUITE GUSTY...WITH N WINDS 20-30 MPH. ACROSS THE KCOS REGION...SNOW SHOULD BECOME A CONCERN BY LATE IN THE AFTERNOON AND LASTING INTO THE EVENING. ACCUMS SHOULD NOT BE A MAIN CONCERN (1-2")...BUT WINDS WILL BE THE MAIN ISSUE. BY LATER THIS EVENING...NORTHERLY WINDS COULD BE APPROACHING 35 KNOTS. THE SNOW AND WINDS SHOULD BEGIN TO DECREASE AFTER MIDNIGHT. WITH N WINDS...CIGS SHOULD NOT BE A MAJOR CONCERN AND SNOW SHOULD NOT BE HEAVY...EXPECT MAINLY MVFR CONDITIONS THROUGH THE WORST OF IT. HOWEVER..IF SNOWS ACCUM A BIT MORE THAN EXPECTED...AND THINGS START BLOWING THEN VIS COULD BE SEVERELY RESTRICTED THIS EVENING DUE TO THE BLOWING SNOW. KPUB...WINDS AND SNOW WILL BE LESS ACROSS KPUB. MAIN ACTIVITY WILL BE THIS EVENING WITH CIGS MAINLY IN THE BKN020-030 RANGE AND VIS RESTRICTIONS 2-3SM. KALS...EXPECT PERIODS OF SNOW IN THE VALLEL DURING THE EVENING PERIOD. BRIEF HEAVY SNOW COULD CAUSE IFR CONDITIONS AT TIMES. && .PUB WATCHES/WARNINGS/ADVISORIES... SNOW AND BLOWING SNOW ADVISORY FROM 6 PM THIS EVENING TO 5 AM MST SATURDAY FOR COZ072-073-078-086>088-093-094-097>099. SNOW AND BLOWING SNOW ADVISORY UNTIL 8 PM MST THIS EVENING FOR COZ058>061-066-068. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 5 AM MST SATURDAY FOR COZ074-075-079-080. SNOW AND BLOWING SNOW ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM MST SATURDAY FOR COZ081-082-084. && $$ 34/27 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1225 AM EST FRI DEC 21 2007 .SYNOPSIS... HIGH PRESSURE OVER QUEBEC WILL BUILD SOUTH INTO NEW ENGLAND AND NEW YORK TODAY. SATURDAY IT WILL SLIDE OFFSHORE AND A SOUTHERLY FLOW OF MILDER AIR WILL BECOME ESTABLISHED OVER THE EASTERN SEABOARD. A STORM WILL ORGANIZE IN THE MID MISSISSIPPI VALLEY SATURDAY AFTERNOON AND INTENSIFY AS IT MOVES THROUGH THE GREAT LAKES REGION TO HUDSON`S BAY SUNDAY. AHEAD OF IT INCREASING MOISTURE WILL BRING A WINTRY MIX OF PRECIPITATION AT FIRST...BUT IT WILL WARM ENOUGH TO CHANGE THE PRECIPITATION TO RAIN...WHICH WILL BE HEAVY AT TIMES SUNDAY AFTERNOON. THE STORMS COLD FRONT WILL SWEEP TROUGH THE REGION SUNDAY NIGHT...AND IT WILL TURN MUCH COLDER. CHRISTMAS EVE AN UPPER LEVEL DISTURBANCE WILL PASS ACROSS THE REGION AND IN THE CHILLY NORTHWEST FLOW WILL TRIGGER SCATTERED SNOW SHOWERS. HIGH PRESSURE WILL BUILD INTO THE REGION FROM ONTARIO CHRISTMAS DAY. && .NEAR TERM /UNTIL 6 AM FRIDAY/... IT SEEMS A NARROW YET PERSIST/INTERMITTENT BAND OF LIGHT SNOW CONTINUES TO IMPACT WESTERN NEW ENGLAND AND ATTEMPTING TO CROSS INTO EASTERN NEW YORK (NORTH OF THE MID HUDSON VALLEY). LATEST RUN OF THE RUC13 AND 00Z NAM/WRF INDICATE THIS IS RESPONSE TO LOW LEVEL CONVERGENCE AND DEFORMATION WHICH IS EXPECTED TO BE INTERMITTENT THROUGH TONIGHT. WILL UPDATE POPS ACCORDINGLY BUT KEEP IT IN THE SLIGHT CHANCE CATEGORY. WHERE IT HAS SNOWED...VISIBILITIES HAVE DROPPED BACK 1-3 MILES...MAINLY ACROSS THE HIGHER ELEVATIONS. THE OTHER CONCERN IS THE TEMPERATURES OVERNIGHT. WITH PERSISTENT CLOUD COVER AND LACK OF ADVECTION...WILL RAISE OVERNIGHT LOWS SEVERAL DEGREES WHICH CORRESPONDS WELL WITH THE 00Z RUN OF THE GFS LAMP. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... THE SURFACE HIGH WILL BE CENTERED TO OUR EAST AND WILL SHIFT OFF THE NEW ENGLAND COAST FRIDAY NIGHT. IT WILL KEEP US DRY WITH A DEVELOPING SOUTHEAST FLOW. LOW LEVEL CLOUDS WILL LIFT FRIDAY BUT HIGH LEVEL CLOUDS WELL IN ADVANCE OFF OF THE SYSTEM FOR THE WEEKEND WILL BE STREAMING IN...SO NOT MUCH SUN EXPECTED. TEMPERATURES WILL BE SEASONABLE. && .LONG TERM /SATURDAY THROUGH THURSDAY/... HIGH PRESSURE SLIDES OFF THE ATLC COAST SATURDAY...AND SOUTHERNLY FLOW INCREASES THROUGH THE DAY. 500HPA RIDGE OVER THE EASTERN SEABOARD. CLOUDS WILL BE VARIABLE AS WAA PRODUCES MID AND HI CLOUDS. MEANWHILE THE LOW LEVEL SOUTHEAST FLOW WILL ALSO BRING MOISTURE INTO THE REGION AND CONSIDERABLE LOW LEVEL MOISTURE REMAINS THAT HAS LINGERED SINCE THURSDAY. SO ALOT OF CLOUDS AND BY SAT AFTN AND EVENING SPOTTY LIGHT DRIZZLE...FREEZING DRIZZLE AND FLURRIES. TEMPERATURES MAY FALL A BIT DURING THE EVENING...BUT INCREASING SOUTHERLY FLOW WILL RESULT IN STEADY OR SLOWLY RISING TEMPS OVERNIGHT. TEMPS WILL STILL BE AROUND OR BLO FREEZING IN MANY AREAS AND PTYPE LIKELY TO BE ZR...BUT AMOUNTS WILL BE LIGHT. RAPIDLY DEEPENING SURFACE LOW IN THE GREAT LAKES SUNDAY WILL PUSH A CDFNT INTO NYS SUN AFTERNOON...WHICH SWEEPS EAST ACROSS REGION BY EVENING. WITH RAPIDLY INCREASE SOUTHERNLY INFLOW AHEAD OF THE SYSTEM TEMPS WILL RISE INTO THE 40S...AND KATAFRONT TYPE DYNAMICS OF SHOWERY/SQUALLY RAINS WILL DEVELOP ALONG AND AHEAD OF CDFNT. ENSEMBLE QPF AMOUNTS FM PLUMES OF 1 TO 2 INCHES LIKELY IN 6 TO 9 HOUR PERIOD. SIGNIFICANT SNOWMELT AND RUNOFF LIKELY. SEE HYDRO SECTION FOR PARTICULARS. THE 500HPA CUTOFF...FOLLOWS ACROSS THE REGION SUNDAY NIGHT AS VERY STRONG CAA FLASH FREEZES ANY REMAINING LIQUID...AND MELTED SNOW. ALSO THE PASSAGE OF THE CUT OFF WILL BE ACCOMPANIED BY SECONDARY ARCTIC CDFNT CHRISTMAS EVE WITH SCT -SHSN IN CAA...WITH STRONG UPPER DYNAMICS...BUT NOT IDEAL SETUP FOR LAKE EFFECT IN FCA. FINALLY SURFACE HIGH AND 500HPA RIDGE BUILD ACROSS THE REGION CHRISTMAS DAY...AND SEASONABLE TEMPS AND MAINLY CLEAR SKIES THE RESULT. BEYOND THEN THE SURFACE HIGH PASSES OFFSHORE...AND THE MODELS DIVERGE ON A VARIETY OF PASSING WEATHER SYSTEMS. WITH CUT OFF LOW ORGANIZING OVER GRTLKS REGION..ONE SFC LOW PASSES WELL SOUTH OF REGION OR THROUGH REGION THURSDAY OR FRIDAY. FOR NOW WENT WITH GFS MOS GUIDANCE AND SCT -SHSN AND CHC SNOW AT END OF EFP. AFTER ALL THE 1.5 PVU ANOMALY THAT WILL ORGANIZE THIS SYSTEM IS CURRENTLY NEAR TOKYO JAPAN. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AN EAST/NORTHEASTERLY FLOW AT LOW LEVELS IS RESULTING IN WIDE SPREAD MVFR TO IFR CEILINGS OVER THE REGION WITH BROKEN TO OVERCAST STRATUS 600 TO 2000 FEET AGL AT MANY OF THE METAR SITES...WITH WIDESPREAD IFR/LIFR CEILINGS AND OBSCURATIONS OVER HIGHER TERRAIN. A CONTINUED FLOW OF VERY MOIST AIR OFF THE ATLANTIC WILL RESULT IN IMPROVEMENT BEING SLOW TO OCCUR. WINDS WILL BE LIGHT FROM THE NORTH AND EAST IN THE EARLY MORNING HOURS...AND EASTERLY AROUND 5 KNOTS DURING THE DAY TODAY. OUTLOOK... TONIGHT...MVFR/IFR DUE TO LOW CLOUDS AND/OR FOG. SAT...VFR...NO SIGNIFICANT WEATHER EXPECTED. SUN...IFR MIXED PCPN...STRONG S-SE WINDS. MON...VFR...EXCEPT MVFR/IFR IN LAKE EFFECT SNOW SHOWERS DOWNWIND OF LAKE ONTARIO TUE...VFR...NO SIGNIFICANT WEATHER EXPECTED. && .HYDROLOGY... NO HYDRO PROBLEMS ARE ANTICIPATED THROUGH SATURDAY. A STRONG STORM SYSTEM WILL IMPACT THE REGION ON SUNDAY. STRONG SOUTHERLY WINDS ARE EXPECTED TO DEVELOP ACROSS THE AREA ON SUNDAY. THIS WILL BRING A WARM SURGE OVER A SNOW PACK THAT CONTAINS 1 TO 3 INCHES OF WATER EQUIVALENT FROM ALBANY SOUTH AND 2 TO 4 INCHES OF WATER EQUIVALENT OVER NORTHERN AREAS. A COLD FRONT WILL CROSS THE AREA SUNDAY EVENING. MODELS HAVE TRENDED WETTER BRINGING AROUND AN INCH OF RAIN TO ALL AREAS IN A 6 HOUR PERIOD SUNDAY AFTERNOON OR EVENING. THE UPPER MOHAWK...MOOSE...UPPER HUDSON AND VERMONT BASINS ARE EXPECTED TO SEE A 6 TO 12 HOUR WARM PERIOD LATE SUNDAY...WHICH WILL PROBABLY NOT BE ENOUGH TO RIPEN THE SNOW. NORTHERN SNOW COVER SHOULD ABSORB THE RAIN WITH MINIMAL RUNOFF BEFORE REFREEZING. HOWEVER...SOUTHERN AREAS MAY SEE 18 TO 24 HOURS OF ABOVE FREEZING TEMPERATURES. THE QUESTION IS HOW MUCH SNOW MELTS. LOCAL RIVER MODELS SHOW THAT STREAMS CAN HANDLE AS MUCH AS TWO INCHES OF COMBINED MELT AND RAIN WITH MINIMAL FLOODING. 3 INCHES OR MORE OF MELT AND RAIN WOULD CAUSE SIGNIFICANT FLOODING. THE GROUND HERE AT ALBANY IS FROZEN TO A DEPTH OF 5 INCHES. FROZEN GROUND ENHANCES THE CHANCES THAT FLOODING...AND POSSIBLY FLASH FLOODING...MAY OCCUR. RIVER ICE COVER IS NOT THICK ENOUGH TO CAUSE ICE JAM PROBLEMS. THE HIGHEST CONFIDENCE IS FOR TIDAL FLOODING LATE SUNDAY ALONG THE MID HUDSON RIVER NEAR KINGSTON AND POUGHKEEPSIE DUE TO STRONG SOUTHERLY WINDS. OTHER BASINS AT RISK FOR FLOODING INCLUDES THE SCHOHARIE...THE LOWER MOHAWK...THE ESOPUS...THE BATTEN KILL...THE HOOSIC...WAPPINGERS CREEK AND THE HOUSATONIC AND ITS TRIBUTARIES FROM FALLS VILLAGE DOWN STREAM. FREEZING TEMPERATURES ARE EXPECTED ACROSS THE ENTIRE AREA BY MONDAY MORNING WHICH WILL END THE RUNOFF. IF FLOODING WERE TO OCCUR IT WOULD MOST LIKELY BEGIN SUNDAY AFTERNOON AND LINGER INTO MONDAY. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...SNYDER NEAR TERM...BGM SHORT TERM...IAA LONG TERM...SNYDER AVIATION...RCK HYDROLOGY...DIRIENZO WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 924 PM EST THU DEC 20 2007 .SYNOPSIS... HIGH PRESSURE OVER QUEBEC WILL BUILD SOUTH INTO NEW ENGLAND AND NEW YORK TONIGHT AND FRIDAY. SATURDAY IT WILL SLIDE OFFSHORE AND A SOUTHERLY FLOW OF MILDER AIR WILL BECOME ESTABLISHED OVER THE EASTERN SEABOARD. A STORM WILL ORGANIZE IN THE MID MISSISSIPPI VALLEY SATURDAY AFTERNOON AND INTENSIFY AS IT MOVES THROUGH THE GREAT LAKES REGION TO HUDSON`S BAY SUNDAY. AHEAD OF IT INCREASING MOISTURE WILL BRING A WINTRY MIX OF PRECIPITATION AT FIRST...BUT IT WILL WARM ENOUGH TO CHANGE THE PRECIPITATION TO RAIN...WHICH WILL BE HEAVY AT TIMES SUNDAY AFTERNOON. THE STORMS COLD FRONT WILL SWEEP TROUGH THE REGION SUNDAY NIGHT...AND IT WILL TURN MUCH COLDER. CHRISTMAS EVE AN UPPER LEVEL DISTURBANCE WILL PASS ACROSS THE REGION AND IN THE CHILLY NORTHWEST FLOW WILL TRIGGER SCATTERED SNOW SHOWERS. HIGH PRESSURE WILL BUILD INTO THE REGION FROM ONTARIO CHRISTMAS DAY. && .NEAR TERM /UNTIL 6 AM FRIDAY/... IT SEEMS A NARROW YET PERSIST/INTERMITTENT BAND OF LIGHT SNOW CONTINUES TO IMPACT WESTERN NEW ENGLAND AND ATTEMPTING TO CROSS INTO EASTERN NEW YORK (NORTH OF THE MID HUDSON VALLEY). LATEST RUN OF THE RUC13 AND 00Z NAM/WRF INDICATE THIS IS RESPONSE TO LOW LEVEL CONVERGENCE AND DEFORMATION WHICH IS EXPECTED TO BE INTERMITTENT THROUGH TONIGHT. WILL UPDATE POPS ACCORDINGLY BUT KEEP IT IN THE SLIGHT CHANCE CATEGORY. WHERE IT HAS SNOWED...VISIBILITIES HAVE DROPPED BACK 1-3 MILES...MAINLY ACROSS THE HIGHER ELEVATIONS. THE OTHER CONCERN IS THE TEMPERATURES OVERNIGHT. WITH PERSISTENT CLOUD COVER AND LACK OF ADVECTION...WILL RAISE OVERNIGHT LOWS SEVERAL DEGREES WHICH CORRESPONDS WELL WITH THE 00Z RUN OF THE GFS LAMP. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... THE SURFACE HIGH WILL BE CENTERED TO OUR EAST AND WILL SHIFT OFF THE NEW ENGLAND COAST FRIDAY NIGHT. IT WILL KEEP US DRY WITH A DEVELOPING SOUTHEAST FLOW. LOW LEVEL CLOUDS WILL LIFT FRIDAY BUT HIGH LEVEL CLOUDS WELL IN ADVANCE OFF OF THE SYSTEM FOR THE WEEKEND WILL BE STREAMING IN...SO NOT MUCH SUN EXPECTED. TEMPERATURES WILL BE SEASONABLE. && .LONG TERM /SATURDAY THROUGH THURSDAY/... HIGH PRESSURE SLIDES OFF THE ATLC COAST SATURDAY...AND SOUTHERNLY FLOW INCREASES THROUGH THE DAY. 500HPA RIDGE OVER THE EASTERN SEABOARD. CLOUDS WILL BE VARIABLE AS WAA PRODUCES MID AND HI CLOUDS. MEANWHILE THE LOW LEVEL SOUTHEAST FLOW WILL ALSO BRING MOISTURE INTO THE REGION AND CONSIDERABLE LOW LEVEL MOISTURE REMAINS THAT HAS LINGERED SINCE THURSDAY. SO ALOT OF CLOUDS AND BY SAT AFTN AND EVENING SPOTTY LIGHT DRIZZLE...FREEZING DRIZZLE AND FLURRIES. TEMPERATURES MAY FALL A BIT DURING THE EVENING...BUT INCREASING SOUTHERLY FLOW WILL RESULT IN STEADY OR SLOWLY RISING TEMPS OVERNIGHT. TEMPS WILL STILL BE AROUND OR BLO FREEZING IN MANY AREAS AND PTYPE LIKELY TO BE ZR...BUT AMOUNTS WILL BE LIGHT. RAPIDLY DEEPENING SURFACE LOW IN THE GREAT LAKES SUNDAY WILL PUSH A CDFNT INTO NYS SUN AFTERNOON...WHICH SWEEPS EAST ACROSS REGION BY EVENING. WITH RAPIDLY INCREASE SOUTHERNLY INFLOW AHEAD OF THE SYSTEM TEMPS WILL RISE INTO THE 40S...AND KATAFRONT TYPE DYNAMICS OF SHOWERY/SQUALLY RAINS WILL DEVELOP ALONG AND AHEAD OF CDFNT. ENSEMBLE QPF AMOUNTS FM PLUMES OF 1 TO 2 INCHES LIKELY IN 6 TO 9 HOUR PERIOD. SIGNIFICANT SNOWMELT AND RUNOFF LIKELY. SEE HYDRO SECTION FOR PARTICULARS. THE 500HPA CUTOFF...FOLLOWS ACROSS THE REGION SUNDAY NIGHT AS VERY STRONG CAA FLASH FREEZES ANY REMAINING LIQUID...AND MELTED SNOW. ALSO THE PASSAGE OF THE CUT OFF WILL BE ACCOMPANIED BY SECONDARY ARCTIC CDFNT CHRISTMAS EVE WITH SCT -SHSN IN CAA...WITH STRONG UPPER DYNAMICS...BUT NOT IDEAL SETUP FOR LAKE EFFECT IN FCA. FINALLY SURFACE HIGH AND 500HPA RIDGE BUILD ACROSS THE REGION CHRISTMAS DAY...AND SEASONABLE TEMPS AND MAINLY CLEAR SKIES THE RESULT. BEYOND THEN THE SURFACE HIGH PASSES OFFSHORE...AND THE MODELS DIVERGE ON A VARIETY OF PASSING WEATHER SYSTEMS. WITH CUT OFF LOW ORGANIZING OVER GRTLKS REGION..ONE SFC LOW PASSES WELL SOUTH OF REGION OR THROUGH REGION THURSDAY OR FRIDAY. FOR NOW WENT WITH GFS MOS GUIDANCE AND SCT -SHSN AND CHC SNOW AT END OF EFP. AFTER ALL THE 1.5 PVU ANOMALY THAT WILL ORGANIZE THIS SYSTEM IS CURRENTLY NEAR TOKYO JAPAN. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... RIDGING BUILDS...HOWEVER...LOW LEVELS ARE VERY MOIST AND HAVE LITTLE WIND FLOW (LIGHT NORTHEAST WIND). MVFR-VFR CONDITIONS WILL LOWER THIS EVENING BACK TO IFR CONDITIONS WHICH WILL PERSIST THROUGH FRIDAY MORNING. THERE COULD ALSO BE PERIOD OF LIFR AFTER 06Z WITH NOCTURNAL COOLING OF THE COLUMN AND SHRINKING DEWPOINT DEPRESSIONS. WITH TEMPERATURES BELOW FREEZING...FREEZING FOG IS CONCERN OVERNIGHT. CONDITIONS SLOWLY IMPROVE FRIDAY BUT LIKELY NOT MUCH BETTER THAN MVFR. OUTLOOK... SAT...VFR...NO SIGNIFICANT WEATHER EXPECTED. SUN...IFR MIXED PCPN...STRONG S-SE WINDS...POSSIBLE LLWS. MON...VFR...EXCEPT MVFR/IFR IN LAKE EFFECT SNOW SHOWERS DOWNWIND OF LAKE ONTARIO...WINDY WITH LLWS POTENTIAL. TUE...VFR...NO SIGNIFICANT WEATHER EXPECTED AT THIS TIME. && .HYDROLOGY... NO HYDRO PROBLEMS ARE ANTICIPATED THROUGH SATURDAY. A STRONG STORM SYSTEM WILL IMPACT THE REGION ON SUNDAY. STRONG SOUTHERLY WINDS ARE EXPECTED TO DEVELOP ACROSS THE AREA ON SUNDAY. THIS WILL BRING A WARM SURGE OVER A SNOW PACK THAT CONTAINS 1 TO 3 INCHES OF WATER EQUIVALENT FROM ALBANY SOUTH AND 2 TO 4 INCHES OF WATER EQUIVALENT OVER NORTHERN AREAS. A COLD FRONT WILL CROSS THE AREA SUNDAY EVENING. MODELS HAVE TRENDED WETTER BRINGING AROUND AN INCH OF RAIN TO ALL AREAS IN A 6 HOUR PERIOD SUNDAY AFTERNOON OR EVENING. THE UPPER MOHAWK...MOOSE...UPPER HUDSON AND VERMONT BASINS ARE EXPECTED TO SEE A 6 TO 12 HOUR WARM PERIOD LATE SUNDAY...WHICH WILL PROBABLY NOT BE ENOUGH TO RIPEN THE SNOW. NORTHERN SNOW COVER SHOULD ABSORB THE RAIN WITH MINIMAL RUNOFF BEFORE REFREEZING. HOWEVER...SOUTHERN AREAS MAY SEE 18 TO 24 HOURS OF ABOVE FREEZING TEMPERATURES. THE QUESTION IS HOW MUCH SNOW MELTS. LOCAL RIVER MODELS SHOW THAT STREAMS CAN HANDLE AS MUCH AS TWO INCHES OF COMBINED MELT AND RAIN WITH MINIMAL FLOODING. 3 INCHES OR MORE OF MELT AND RAIN WOULD CAUSE SIGNIFICANT FLOODING. THE GROUND HERE AT ALBANY IS FROZEN TO A DEPTH OF 5 INCHES. FROZEN GROUND ENHANCES THE CHANCES THAT FLOODING...AND POSSIBLY FLASH FLOODING...MAY OCCUR. RIVER ICE COVER IS NOT THICK ENOUGH TO CAUSE ICE JAM PROBLEMS. THE HIGHEST CONFIDENCE IS FOR TIDAL FLOODING LATE SUNDAY ALONG THE MID HUDSON RIVER NEAR KINGSTON AND POUGHKEEPSIE DUE TO STRONG SOUTHERLY WINDS. OTHER BASINS AT RISK FOR FLOODING INCLUDES THE SCHOHARIE...THE LOWER MOHAWK...THE ESOPUS...THE BATTEN KILL...THE HOOSIC...WAPPINGERS CREEK AND THE HOUSATONIC AND ITS TRIBUTARIES FROM FALLS VILLAGE DOWN STREAM. FREEZING TEMPERATURES ARE EXPECTED ACROSS THE ENTIRE AREA BY MONDAY MORNING WHICH WILL END THE RUNOFF. IF FLOODING WERE TO OCCUR IT WOULD MOST LIKELY BEGIN SUNDAY AFTERNOON AND LINGER INTO MONDAY. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...SNYDER NEAR TERM...BGM SHORT TERM...IAA LONG TERM...SNYDER AVIATION...BGM HYDROLOGY...DIRIENZO WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 654 AM EST THU DEC 20 2007 .SYNOPSIS... LOW PRESSURE WELL SOUTHEAST OF CAPE COD WILL MOVE EAST TODAY...AS THE UPPER LEVEL LOW ASSOCIATED WITH THE SYSTEM CONTINUES SCATTERED SNOW SHOWERS THROUGH THE AFTERNOON. HIGH PRESSURE WILL BUILD IN FROM EASTERN QUEBEC THURSDAY NIGHT INTO FRIDAY. THE HIGH WILL MOVE SOUTHWARD FRIDAY NIGHT TO NEAR THE GULF OF MAINE. A RETURN SOUTHERLY FLOW OF MILD AIR WILL OCCUR ON SATURDAY WITH TEMPERATURES ABOVE NORMAL FOR LATE DECEMBER. A COLD FRONT PROGRESSING SLOWLY EAST FROM THE MISSISSIPPI RIVER VALLEY ON SATURDAY...WILL BRING RAIN AND WINDY CONDITIONS FOR SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE LATEST RUC ANALYSIS COUPLED WITH NEIGHBORING RADARS THIS MORNING DEPICTS SECONDARY COASTAL REDEVELOPMENT OCCURRING WELL SOUTHEAST OF NANTUCKET WITH THE PRIMARY CLIPPER WEAKENING OVER CNTRL NY. A SHORT WAVE PIVOTING AROUND THE CLOSED 500 MB LOW IS MOVING ACROSS ERN NY...WHICH IS HELPING TO FOCUS SOME OF THE -SN ACTIVITY. MOST SNOWFALL REPORTS IN OUR FCST AREA WERE IN THE HALF AN INCH TO TWO INCH RANGE EARLY THIS MORNING. ADDITIONAL SNOW AMOUNTS OF A DUSTING TO AN INCH OR SO WILL BE POSSIBLE...EXCEPT A LITTLE MORE IS LIKELY OVER SRN VT. THE SHORT WAVE ENERGY ROUNDING THE BASE OF THE LONG WAVE TROUGH SHOULD ALLOW THE COASTAL WAVE TO CONTINUE TO DEEPEN AND INTENSIFY...HOWEVER...THE AMOUNT OF MOISTURE/QPF DRAWN BACK UPSTREAM INTO OUR FCST AREA WILL BE LIMITED. SOUTHEASTERN VT /WINDHAM COUNTY/ MAY RECEIVE ANOTHER 1-4" OF SNOW TODAY...AS THE 850 MB CLOSED CIRCULATION IS JUST EAST OF CAPE COD 12Z-18Z. THE 850-700 MB DEFORMATION ZONE WITH WEAK TO MODERATE MID LEVEL FRONTOGENESIS EXTENDS TO THE W/NW ENOUGH FOR PERIODS OF LIGHT TO POSSIBLY MODERATE SNOW NORTHEAST OF THE CAPITAL REGION. FOR THE REST OF THE FORECAST AREA...STEEP LOW TO MID LEVEL LAPSE RATES...LOTS OF LOW LEVEL MOISTURE...AND CYCLONIC VORTICITY ADVECTION WILL KEEP SCT SNOW SHOWERS/FLURRIES AROUND THROUGH MOST OF THE DAY. ENOUGH WARMING IN THE BOUNDARY LAYER MAY EVEN ALLOW ONLY RAIN SHOWERS OR SPRINKLES IN THE MID HUDSON VALLEY. 850 MB TEMPS OF ABOUT -6C TO -8C SHOULD ALLOW HIGHS IN THE L30S TO U30S IN THE VALLEYS...AND M20S TO L30S IN THE HILLS AND MTNS. WE LEANED CLOSE TO THE GFSMOS MAX TEMP VALUES. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... THURSDAY NIGHT...THE UPPER LEVEL LOW MIGRATES DOWNSTREAM WITH ANY LEFTOVER SNOW SHOWERS/FLURRIES ENDING AROUND MIDNIGHT. WEAK 850 MB COLD AIR ADVECTION OCCURS WITH A 1037 HPA SFC ANTICYCLONE BUILDING SOUTH/SOUTHEAST FROM ERN QUEBEC/THE GULF OF ST LAWRENCE. THIS IS NOT AN ARCTIC AIR MASS. IT WILL MORE OF THE POLAR VARIETY WITH SEASONABLY COLD AIR AT BEST. IT WILL TAKE SOME TIME TO SCOUR OUT ALL THE LOW LEVEL MOISTURE WITH THE UPPER LEVEL LOW. THE BUFKIT PROFILES FROM KALB/KGFL/KPOU FROM THE GFS/NAM-WRF SHOW A FAIR AMOUNT OF MOISTURE LINGERING BELOW 5 KFT...SO CLOUDY/MOSTLY CLOUDY CONDITIONS SHOULD DO IT HERE. FRIDAY-SATURDAY...A FAIRLY QUIET STRETCH OF WEATHER WITH HIGH PRESSURE BUILDING OVER NY AND NEW ENGLAND. WE SHOULD SEE A FEW BREAKS OF SUNSHINE BY FRIDAY AFTERNOON. 925 HPA TEMPS OVER THE CAPITAL REGION WILL BE AROUND -5C...SO SEASONABLE HIGH TEMPS IN THE 30S IN THE VALLEYS LOOK FINE. HEIGHTS WILL CONTINUE TO RISE ALOFT AS A TROUGH FORMS UPSTREAM OVER THE 4 CORNERS AND EAST OF THE ROCKY MTN REGION. THE 500 MB RIDGE AXIS BEGINS TO MOVE OVER THE NORTHEAST BY 12Z SAT. FRIDAY NIGHT IS TRICKY IN TERMS OF TEMPS. LIGHT TO CALM WINDS AND CLEARING SKIES MAY ALLOW SOME RADIATIONAL COOLING. THE NAM/GFS GUIDANCE WANTS TO INCREASE MID AND HIGH CLOUDS WITH THE H850-700 WARM AIR ADVECTION. WE WENT COLDER THAN THE MOS GUIDANCE AND LEANED TOWARD THE POSSIBILITY OF RADIATIONAL COOLING AND COLD TEMPS...ESPECIALLY NORTH OF THE CAPITAL REGION. SATURDAY SHOULD BE MAINLY DRY...BUT WITH SOME INCREASING MID AND HIGH CLOUDS. WE MAY SEE A SPRINKLE/FLURRY WEST OF THE HUDSON RIVER VALLEY LATE IN THE DAY. WE LIKED THE DRY SCENARIO DEPICTED BY THE NAM/CAN GGEM. 850 MB TEMPS RISING CLOSE TO 0C SHOULD ALLOW TEMPS TO GET ABOVE NORMAL IN THE U30S TO L40S IN THE VALLEYS. THE ETAMOS GUIDANCE LOOKED WAY TOO COLD WITH THE SFC HIGH SOUTH OF PRINCE EDWARD ISLAND SAT MORNING. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... A STRONG SOUTHERLY FLOW IS EXPECTED TO DEVELOP ACROSS FA LATE SATURDAY NIGHT AHEAD OF NEXT SHORT WAVE WHICH IS EXPECTED TO DEEPEN RAPIDLY AS IT LIFTS NORTHEAST THROUGH UPPER GREAT LAKES REGION SUNDAY AND DRAGS A COLD FRONT THROUGH OUR REGION SUNDAY EVENING. AT THIS POINT IT LOOKS AS THOUGH TEMPS WILL BE STEADY OR SLOWLY RISING ON SATURDAY NIGHT WHICH WILL LIKELY RESULT IN SOME MIXED PCPN MAINLY IN THE FORM OF FREEZING RAIN AND SLEET SATURDAY NIGHT BASED ON PARTIAL THICKNESS VALUES WITH A TRANSITION TO RAIN ACROSS THE ENTIRE FA BY SUNDAY MORNING. THE PCPN SATURDAY NIGHT LOOKS TO BE FAIRLY LIGHT WITH THE POTENTIAL FOR AT LEAST A HALF INCH TO AN INCH OF QPF ON SUNDAY WHICH WILL RESULT IN SOME HYDRO CONCERNS...SEE HYDROLOGY DISCUSSION. 00Z MREF PLUME DIAGRAM WOULD GIVE KALB 0.2 TO 2.0 INCHES WITH VERY LITTLE CLUSTERING RESULTING IN A LARGE SPREAD AMONGST ENSEMBLE MEMBERS. QUITE A FEW ENSEMBLE MEMBERS ALSO INDICATE A BRIEF PERIOD OF FREEZING RAIN ON SATURDAY NIGHT BEFORE A QUICK CHANGEOVER TO RAIN AND MOSTLY RAIN UNTIL PCPN TAPERS OFF AS A LIGHT SNOW ACCUMULATION SUNDAY NIGHT. 00Z MREFS ALSO HAS THE LOW PRESSURE CENTER DEEPEN RAPIDLY AS IT TRACKS NORTH OF UPPER GREAT LAKES INTO CANADA ENDING UP 2-3 SD BELOW NORMAL AT 06Z MON WHILE H8 V COMPONENT WINDS NOW 3-4 SD ABOVE NORMAL IMPLYING STRONG SOUTHERLY COMPONENT AT 18Z SUNDAY THIS EVENT WILL NEED TO BE MONITORED CLOSELY FOR BOTH WIND CONCERNS AND HYDRO CONCERNS. AREAS PRONE TO STRONG SOUTHERLY WINDS SUCH AS TACONICS AND SOUTHERN VERMONT AND NORTHERN BERKSHIRES WOULD BE MOST AT RISK OF STRONGEST GUSTS WHICH COULD EASILY TOP 50 MPH IN SOME OF THE MOST PRONE LOCATIONS SUNDAY. IN WAKE OF FRONT SUNDAY NIGHT WINDS EXPECTED TO SHIFT TO THE WEST WITH GUSTS STILL STRONG ACROSS HIGHER TERRAIN OF ADIRONDACKS. GFS 0-30 MB AGL WINDS INDICATE POTENTIAL FOR 50+ KNOT GUSTS FROM THE SOUTH SUNDAY AND FROM THE WEST SUNDAY NIGHT. THE WINDS ARE EXPECTED TO BE AMPLIFIED AS PRESSURE GRADIENT TIGHTENS ACROSS FA BETWEEN DEPARTING 1035 MB HIGH PRESSURE OFF NEW ENGLAND COAST AND LOW PRESSURE MOVING FROM UPPER GREAT LAKES INTO SOUTHERN CANADA AND DEEPENING TO BELOW 990 MB. THIS STRONG PRESSURE GRADIENT IS ALSO SUPPORTED BY ECMWF AND GEM GLOBAL WITH SOME DIFFERENCES IN EXACT LOCATION OF MAIN FEATURES. QPF AMOUNTS OF AT LEAST 0.50 TO 1 INCH EXPECTED AND HYDRO CONCERNS ARE ADDRESSED IN HYDROLOGIC DISCUSSION. EVEN THOUGH THIS SYSTEM IS STILL 3-4 DAYS OUT WILL INCLUDE MENTION OF POTENTIAL FOR FREEZING RAIN...HIGH WINDS AND POSSIBLE FLOODING IN THE HWO. LATE SUNDAY NIGHT AND MONDAY EXPECT SOME LAKE EFFECT SNOW ACROSS THE WESTERN ADIRONDACKS WHICH IS LIKELY TO BE ENHANCED BY A STRONG VORT AXIS ACROSS THIS REGION ON MONDAY. DRY WEATHER IS THEN EXPECTED TO RETURN ON CHRISTMAS EVE AND CHRISTMAS DAY. ALTHOUGH A COASTAL SYSTEM LOOKS TO PASS FAR ENOUGH SOUTHEAST OF THE SOUTHERN NEW ENGLAND COAST ON TUESDAY NIGHT TO SPARE FA SNOW...BUT DUE TO IT BEING A CLOSE CALL BASED ON THE ECMWF AND GFS WILL LEAVE SLIGHT CHANCE TO CHANCE POPS IN FORECAST FOR NOW. BOTH MODELS INDICATE THAT A STRENGTHENING RIDGE OF HIGH PRESSURE ACROSS FA IS EXPECTED TO DEFLECT COASTAL LOW OUT TO SEA. THIS WILL NEED TO BE MONITORED FOR FURTHER MODEL RUN CONTINUITY AS THIS IS MUCH FARTHER SOUTH AND EAST THAN TRACK WAS INDICATED YESTERDAY. IF THIS SYSTEM MISSES OUR FA THEN DRY WEATHER WILL CONTINUE THROUGH WEDNESDAY WITH NEXT SHORT WAVE NOT EXPECTED BEFORE THURSDAY. OVERALL LONG TERM BEYOND MONDAY LOOKS COLD AND DRY AT THIS POINT IN TIME. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... VERY MOIST LOW LEVELS WITH TEMPS HOVERING AROUND THE FREEZING MARK ALONG WITH LITTLE AIR CIRCULATION AND STILL SOME LIGHT SNOW FALLING WILL KEEP LIFR/IFR CONDITIONS IN PLACE FOR MOST IF NOT ALL OF THE MORNING...ALTHOUGH THE SNOW WILL GRADUALLY DIMINISH IN COVERAGE AND INTENSITY DURING THE NEXT COUPLE OF HOURS. THE BIG QUESTION CONTINUES TO BE HOW QUICKLY CIGS AND VSBYS WILL RISE LATER THIS MORNING OR EARLY THIS AFTERNOON. BASED ON BUFKIT MODEL SOUNDINGS CLOUD AND INVERSION HEIGHTS REMAIN IN IFR RANGE THROUGH AT LEAST 15Z AT KGFL AND KPOU...BUT KALB MAY HAVE MOST DIFFICULTY BREAKING OUT OF LIFR/IFR RANGE AS SNOW SHOWER AND FLURRY ACTIVITY MAY END LAST IN CAPITAL DISTRICT. THERE IS ALSO SOME UNCERTAINTY HEADING INTO THIS EVENING...BUT WITH LOW LEVELS STILL MOIST AND LIGHT WINDS EXPECT AT LEAST A RETURN TO MVFR CONDITIONS AFTER 00Z. WINDS GENERALLY LIGHT AND VARIABLE THROUGH 12Z FRIDAY. OUTLOOK... FRI-SAT...VFR. SUN...IFR MIXED PCPN...STRONG S-SE WINDS. MON...VFR...EXCEPT MVFR/IFR IN LAKE EFFECT -SHSN DOWNWIND OF LK ONT. && .HYDROLOGY... NO HYDRO PROBLEMS ARE ANTICIPATED THROUGH SATURDAY. WE HAVE ANNOTATED BOTH THE RVDALY TEXT PRODUCT AND THE AHPS PAGES WHERE ICE IS CAUSING UNREPRESENTATIVE RIVER STAGE AND FLOW READINGS. SOME PERIODS OF LIGHT SNOW EXPECTED TODAY. A STRONGER STORM SYSTEM MAY IMPACT THE REGION ON SUNDAY. THE STORM IS EXPECTED TO MOVE NORTH OF THE GREAT LAKES AND DRAG A COLD FRONT ACROSS OUR REGION LATE SUNDAY. AHEAD OF THE FRONT...TEMPERATURES ARE EXPECTED TO RISE ABOVE FREEZING WITH THE WARMEST TEMPERATURES OVER ULSTER...DUTCHESS AND LITCHFIELD COUNTIES. SOME RUNOFF IS EXPECTED ON SUNDAY SOUTH OF I-90 FROM A COMBINATION OF SNOW MELT AND RAINFALL. 00Z MREFS SHOW A 75 PERCENT CHANCE OF A HALF INCH OF RAIN...AND 30 TO 50 PERCENT CHANCE OF OVER ONE INCH OF RAIN. AT THIS TIME RIVER FLOODING IS NOT EXPECTED BUT THERE IS A THREAT THAT FLOODING COULD DEVELOP... ESPECIALLY OVER SOUTHERN COUNTIES...IF TEMPERATURES TURN OUT WARMER AND RAINFALL IS HEAVIER. LOCALIZED FLOODING IS POSSIBLE IN SOUTHERN URBAN AREAS WHERE STORM DRAINS ARE BLOCKED BY SNOW. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...WASULA SHORT TERM...WASULA LONG TERM...11 AVIATION...11 HYDROLOGY...11 ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1257 AM EST THU DEC 20 2007 .SYNOPSIS... A CLIPPER LOW PRESSURE SYSTEM WILL DISSIPATE IN IN THE EASTERN GREAT LAKES REGION THIS EVENING...WITH A SECONDARY LOW FORMING OFF CAPE COD OVERNIGHT. THESE LOWS WILL BRING PERIODS OF LIGHT SNOW TO THE REGION INTO THURSDAY. HIGH PRESSURE WILL BUILD BACK IN THURSDAY NIGHT INTO FRIDAY AND SLIDE OFFSHORE SATURDAY. SATURDAY NIGHT AND SUNDAY A COLD FRONT WILL PUSH THROUGH THE REGION...WARMER AIR WILL STREAM INTO THE REGION AHEAD OF THE FRONT...RESULTING IN THE THREAT OF MIXED PRECIPITATION CHANGING TO RAIN SUNDAY. HIGH PRESSURE WILL BUILD FROM THE GREAT LAKES INTO QUEBEC MONDAY AND TUESDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... SHORT WAVE WAS PROGRESSING ACROSS UPSTATE NEW YORK WITH A WIDESPREAD AREA OF LIGHT SNOW IMPACTING MOST OF THE CWA (MAINLY THE EASTERN HALF). IT SEEMS A LOCAL HUDSON VALLEY CONVERGENCE ZONE HAS EVOLVED COMBINING WITH FAVORABLE UPSLOPE CONDITIONS FOR A BAND OF LIGHT-MODERATE SNOW. 18Z WRF/NAM AND LATEST RUC13 ALSO SHOW SOME HINTS IN THE LOW LEVEL CONVERGENCE FIELDS ALONG WITH INCREASING DEFORMATION/TROWAL AXIS ACROSS WESTERN NEW ENGLAND INTO PORTIONS OF LAKE GEORGE AND SARATOGA REGION. THESE REGIONS WILL LIKELY REMAIN WITHIN A FAVORABLE SNOWFALL REGION WHILE AREAS TO THE WEST...WE ARE LOSING ICE NUCLEI AS MID AND HIGHER LEVEL DRIER AIR ADVECTS INTO THE REGION. WILL NEED TO MONITOR FZDZ BUT NOTHING REPORTED THUS FAR UPSTREAM. TEMPERATURES ARE NOW AT OR BELOW THE FREEZING MARK WHICH SHOULD SIGNIFY SOME ACCUMULATIONS. MADE SOME MODIFICATIONS TO THE FORECAST/GRIDS BASED ON THOSE AFOREMENTIONED TRENDS AND CURRENT GUIDANCE. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 AM FRIDAY/... BY 12Z/THURSDAY COASTAL LOW IS THE DOMINATE LOW WITH BAGGINESS IN THE PRESSURE FIELDS ACROSS THE FORECAST AREA. IN ADDITION...A SHORT WAVE WILL ROTATE THROUGH THE UPPER LEVEL TROUGH OVER THE REGION THURSDAY. LIGHT SNOW SHOULD LINGER OVER SOUTHERN VERMONT WITH SOME SNOW SHOWERS ACROSS THE REST OF THE FORECAST AREA. CHANCES FOR PRECIPITATION WILL DECREASE AS THE DAY WEARS ON DAY. HIGH PRESSURE TO THE NORTH OVER EASTERN CANADA WILL BUILD SOUTH THURSDAY NIGHT. && .LONG TERM /FRIDAY THROUGH THURSDAY/... FIRST PART OF PERIOD FRIDAY AND SATURDAY FAIRLY QUIET AS SFC HIGH PRESSURE BUILDS ACROSS GREAT LAKES INTO QUEBEC. SATURDAY NIGHT IT SLIDES OFF SHORE AS 500HPA RIDGE BUILDS ALONG EASTERN SEABOARD. CDFNT PUSHES THROUGH GRTLKS SAT NIGHT AND ACROSS NY AND NEW ENG SUNDAY. MAJOR DYNAMICS WITH SYSTEM ARE WELL NORTH OF REGION IN QUEBEC WITH MAIN IMPACT BEING THE CDFNT. WITH PERIOD OF SOUTHERLY WINDS TEMPS WILL HOLD OR RISE SAT NIGHT...BUT WILL START SUFFICIENTLY COLD TO RESULT IN MIXED PCPN TYPES INTO SUN MRNG. PCPN WILL BE SPOTTY IN THE MOISTURE INFLOW AND BULK OF IT WILL BE ASSOCIATED WITH CFP. TEMPS WILL RISE ENOUGH TO TURN THE MIX TO RAIN IN MOST OF FCA PRIOR TO CFP. IN GENERAL ENSEMBLES CENTERED AROUND 0.75 INCH OF QPF WITH THIS EVENT..SOME PORTION OF WHICH WILL BE FROZEN. TREND HAS BEEN TWRD LOWER QPF. THIS IS COVERED IN MORE DETAIL IN HYDRO SECTION. THIS IS A SYSTEM THAT THE MAIN LOW IS WELL TO THE NORTH...ESSENTIALLY A CLIPPER...HAS LIMITED PERIOD OF MOISTURE INFLOW FROM THE ATLC. CDFNT SWEEPS QUICKLY OFFSHORE SUNDAY NIGHT AS HIGH PRESSURE BUILDS EAST FROM THE GRTLKS...FOLLOWED BY A SECONDARY ARCTIC FRONT ON MONDAY. MONDAY AND TUESDAY WILL BE MAINLY DRY EXCEPT FOR -SHSN ASSOCIATED WITH SECONDARY FRONT AND FLOW INTERACTIONS WITH TRRN. TUESDAY INTO WEDNESDAY THERE IS QUITE A BIT OF DIVERGENCE BETWEEN THE GFSMOS...EUROPEAN AND HPC. WITH THE GFS TAKING A LARGE LOW THROUGH THE TENNESSEE VALLEY AND THEN A SECONDARY FORMING OVER DELMARVA AS EARLY AS CHRISTMAS DAY. THE OTHERS DEVELOP THIS SYSTEM ALONG THE SE US COAST...AND TAKE IT UP THE SEABOARD EITHER AS SOME SORT OF SNOW EVENT...OR TOO FAR EAST TO AMOUNT TO ANYTHING. FOR NOW CHC OF SNOW WILL SUFFICE...WE ARE TALKING ABOUT DAYS 7/8. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... VERY MOIST LOW LEVELS WITH TEMPS HOVERING AROUND THE FREEZING MARK ALONG WITH LITTLE AIR CIRCULATION AND STILL SOME LIGHT SNOW FALLING WILL KEEP LIFR/IFR CONDITIONS IN PLACE FOR MOST IF NOT ALL OF THE REMAINDER OF THE OVERNIGHT PERIOD. THE BIG QUESTION AT THIS POINT WILL BE HOW QUICKLY CIGS AND VSBYS WILL RISE AFTER SUNRISE AND EXPECT THAT AT KGFL IT MAY TAKE UNTIL AFTERNOON AS LITTLE WIND FLOW EXPECTED. KALB AND KPOU HAVE A BETTER CHANCE TO MIX AND ALSO EXPECT LESS IN THE WAY OF SNOW SHOWER ACTIVITY AS CLIPPER TYPE SYSTEM PULLS AWAY FROM FA. EVEN AT KALB AND KPOU IT MAY TAKE MUCH OF THE MORNING BEFORE MVFR CONDITIONS GIVE WAY TO VFR. THERE IS SOME UNCERTAINTY HEADING INTO THIS EVENING...BUT WITH LOW LEVELS STILL MOIST AND LIGHT WINDS EXPECT AT LEAST A RETURN TO MVFR CONDITIONS AFTER 00Z. WINDS GENERALLY LIGHT AND VARIABLE THROUGH 06Z FRIDAY...EXCEPT NORTHWEST AT 5-8 KTS AT KALB BETWEEN 12Z AND 00Z. OUTLOOK... FRI-SAT...VFR. SUN...IFR MIXED PCPN...STRONG S-SE WINDS. MON...VFR...EXCEPT MVFR/IFR IN LAKE EFFECT -SHSN DOWNWIND OF LK ONT. && .HYDROLOGY... NO HYDRO PROBLEMS ARE ANTICIPATED THROUGH SATURDAY. WE HAVE ANNOTATED BOTH THE RVDALY TEXT PRODUCT AND THE AHPS PAGES WHERE ICE IS CAUSING UNREPRESENTATIVE RIVER STAGE AND FLOW READINGS. SOME PERIODS OF LIGHT SNOW EXPECTED TONIGHT AND THURSDAY. A STRONGER STORM SYSTEM MAY IMPACT THE REGION ON SUNDAY. THE STORM IS EXPECTED TO MOVE NORTH OF THE GREAT LAKES AND DRAG A COLD FRONT ACROSS OUR REGION LATE SUNDAY. AHEAD OF THE FRONT...TEMPERATURES ARE EXPECTED TO RISE ABOVE FREEZING WITH THE WARMEST TEMPERATURES OVER ULSTER...DUTCHESS AND LITCHFIELD COUNTIES. SOME RUNOFF IS EXPECTED ON SUNDAY SOUTH OF I-90 FROM A COMBINATION OF MELT AND RAINFALL. MODEL ENSEMBLES SHOW A 75 PERCENT CHANCE OF A HALF INCH OF RAIN...AND LESS THAN 30 PERCENT CHANCE OF OVER ONE INCH OF RAIN. AT THIS TIME RIVER FLOODING IS NOT EXPECTED BUT THERE IS A THREAT THAT FLOODING COULD DEVELOP...ESPECIALLY OVER SOUTHERN COUNTIES...IF TEMPERATURES TURN OUT WARMER AND RAINFALL IS HEAVIER. LOCALIZED FLOODING IS POSSIBLE IN SOUTHERN URBAN AREAS WHERE STORM DRAINS ARE BLOCKED BY SNOW. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ AVIATION...11 ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 859 AM EST FRI DEC 21 2007 .SYNOPSIS... A STRONG UPPER-LEVEL DISTURBANCE WHICH WILL PASS THROUGH THE REGION AND MOVE OFF THE COAST TODAY. THIS WILL ENHANCE A WEDGE PATTERN OVER THE CAROLINAS THAT SHOULD HOLD UNTIL BREAKING DOWN ON SUN AS A COLD FRONT APPROACHES FROM THE W. THE FRONT WILL MOVE OFF THE COAST BY EARLY MON...BUT UNSETTLED WEATHER COULD RETURN BY CHRISTMAS DAY AS ANOTHER UPPER LEVEL DISTURBANCE IS POSSIBLE. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 06Z GFS/RUC HAVE CONVERGED ON A SIMILAR SOLUTION WHICH PUTS A SFC LOW NEAR THE W WALL OF THE GULF STREAM SE OF CHARLESTON THIS AFTN. ALMOST A 12 MB PRES GRAD FORECAST INDICATES A WINDY SETUP. NAM SHOWS 60 KT H925 WINDS THIS AFTN...LIKELY OVERDONE BUT WORRISOME. IMPRESSIVE DEFORMATION AXIS ALONG AND JUST W OF I-95 HAS FUELED A ZONE OF 3-6 INCH RNFL AMOUNTS FROM HARDEEVILLE AND PORT WENTWORTH SW TO LONG AND TATTNALL COUNTIES. A FLOOD ADVISORY FOR MINOR FLOODING IS IN EFFECT THROUGH MID MORNING FOR QUITE A FEW OF OUR COUNTIES. ZONES HAVE BEEN UPDATED THIS MORNING TO REFLECT HEAVY RAIN AND INCREASE QPF. RADAR AND GROUND OBSERVATION RECENTLY INDICATED OVER 5 INCHES OF RAIN HAS ALREADY FALLEN AT THE SAVANNAH AIRPORT. THIS RNFL MAX EXTENDS NWD TO AROUND HARDEEVILLE. RAIN ALONG THE NW SIDE OF THE LOW LEVEL WARM FRONT MAY BE A BIT SLOWER TO PULL OUT OF THE ERN PART OF THE FA TODAY. THE EJECTING SFC LOW OFF THE GEORGIA COAST THIS MORNING SHOULD ENHANCE A CLASSIC WEDGE SETUP TODAY. WE INDICATED HIGH TEMPS IN OUR NW TIER WILL OCCUR DURING THIS MORNING...FALLING AFTERNOON. VERY LITTLE CHANGE TO OVERALL TEMPERATURE SCHEME OVERALL. WINDS SHOULD INCREASE THIS AFTERNOON. WILL NEED TO WATCH FOR WIND ADVISORY CRITERIA POSSIBILITIES ALONG THE IMMEDIATE CHARLESTON COUNTY COAST AT SOME POINT LATER TODAY. THE COMBINATION OF STRONG PINCHING...DEEPENING LOW OVER THE ATLC AND RAPID PRES RISES IN ITS WAKE WILL RESULT IN STRONG AND GUSTY WINDS OVER THE COASTAL COUNTIES TODAY. HIGHEST WINDS WILL BE NEAR THE COAST...AND MOST NOTABLY ACROSS CHARLESTON COUNTY. WE HAVE THUS INITIATED A HIGH WIND ADVISORY. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... HEAVIER PRECIP SHOULD HAVE TAPERED OFF BY TONIGHT EXCEPT FOR A FEW CONVECTIVE SHOWERS POSSIBLE OVER FAR NE PORTIONS. HOWEVER... CONTINUED WEDGE PATTERN WITH WEAK ISENTROPIC LIFT COULD RESULT IN SOME DRIZZLE THROUGH THE NIGHT IN MANY AREAS. EXTENSIVE CLOUD COVER AND A RATHER CONTIGUOUS AIRMASS IN PLACE SHOULD KEEP TEMPERATURES FAIRLY STEADY THROUGH THE NIGHT OR SLIGHTLY FALLING. GUIDANCE TEMPS FOR SAT SEEM MUCH TOO HIGH OVER THE NORTHERN HALF OF THE AREA. MID TO UPPER 60S IS PRETTY MUCH OUT OF THE QUESTION ASSUMING THE WEDGE OF HIGH PRES REMAINS FIRMLY PLANTED ACROSS THE EASTERN SEABOARD. WE SHOULD HAVE A LARGE TEMP GRADIENT ACROSS THE AREA WITH UPPER 60S FAR S TO UPPER 50S N. DECREASED POPS TO SLIGHT CHANCE OVER SE SC WHERE BEST CHANCE OF SOME ISENTROPIC ALONG THE COASTAL TROUGH WILL EXIST. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... WHILE MODEL SOLUTIONS REMAIN SPLIT FOR MOST OF THE EXTENDED... CONFIDENCE THAT THE GUIDANCE IS RUNNING TOO WARM IS QUITE HIGH. MUCH OF THE LONG-TERM PERIOD WILL BE DOMINATED BY A WEDGE PATTERN WITH HIGH PRES OVER THE NE STATES. AS USUAL WITH PERSISTENT WEDGE PATTERNS IN THIS PART OF THE COUNTRY...THE GFS MOS TEMPS ARE ABOUT TEN DEGREES TOO WARM ON AVERAGE. THIS STILL SEEMS TO BE THE CASE WITH THE 00Z RUN. INHERITED GRIDS SEEM QUITE REASONABLE AND ARE WELL COLLABORATED ON THE WHOLE...THUS DID NOT MAKE SIGNIFICANT CHANGES TO THESE PERIODS. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... SFC LOW AT 11Z WAS CLOSE TO MOVING OFF THE GEORGIA COAST S OF KSAV AND WINDS WERE ALREADY BACKING IN NRN CHATHAM COUNTY INDICATING THE LOW IS SLIPPING OF THE SSE. HEAVY RNFL IS PINNED DOWN AROUND THE SAVANNAH AIRPORT AND VSBYS AND CIGS SHOULD CONTINUE TO BOUNCE WITH THE PRECIP LOADING. STRONG LOW LEVEL CONVERGENCE IS INCREASING FURTHER UP THE COAST AND HEAVY RAINS MAY ALSO BECOME PINNED ALONG THE CHARLESTON COUNTY LATER THIS MORNING. IN EITHER CASE...IFR/MVFR CONDITIONS SHOULD BECOME LIFR BY THIS AFTERNOON AS THE WEDGE INVERSION LOWERS AND STRENGTHENS. LIFR CIGS TONIGHT...VERY LOW CONFIDENCE ON VSBYS IN THE WEDGE. AT BOTH TAF SITES...N TO NE WINDS SHOULD BE GUSTY FROM THIS AFTN THROUGH THIS EVENING...HIGHEST AT KCHS. THIS IS DEPENDANT ON THE EVOLUTION OF A VERY COMPLEX SYNOPTIC REGIME. EXTENDED AVIATION OUTLOOK...LIFR OR LOWER CIGS AND REDUCED VSBYS IN FOG SAT MORNING...LIFTING TO MVFR CIGS SAT AFTN. LOW CIGS MAY REDEVELOP SAT NIGHT. THERE SHOULD BE SOME IMPROVEMENT BY SUNDAY NIGHT AND MONDAY...BUT ANOTHER ROUND OF LOW CIGS IS POSSIBLE TUESDAY AND TUESDAY NIGHT. && .MARINE... KJAX SOUNDING SHOWS 35-40 KT BELOW 2K FT THIS MORNING AND STRONG PINCHING IS DEVELOPING AND WILL STRENGTHEN FURTHER AS LOW DEEPENS AS IT REACHES THE GULF STREAM. WITH STRONG PRES RISES IN WAKE OF THE LOW WILL GO AHEAD AND RAISE A GALE WARNING FOR AMZ352-354-374. THUS ALL WATERS ARE NOW UNDER A GALE WARNING. HAVE RAISED SEAS/WAVES ACCORDINGLY. HAVE ALSO ADDED TSTMS TO THE SC WATERS AND LOWERED COVERAGE OVER PRECIP ON THE SE GA WATERS. STRONG GRAD PINCHING IS LIKELY TODAY THROUGH EARLY TONIGHT GIVEN THE DYNAMICS AND THERMAL GRADIENT/DIABATIC EFFECT. WHILE THE NAM MODEL SEEMS A BIT QUESTIONABLE WITH THE TRACK OF THE SFC LOW TODAY... THE GFS REMAINS ON TRACK...ALBEIT WEAK WITH THE WIND SPEEDS GIVEN THE TILTING WEDGE SCENARIO. WE HAVE UPGRADED GALE WATCH TO A WARNING OFF THE CHARLESTON COUNTY COAST AND INCLUDED THE HARBOR FOR TODAY INTO TONIGHT. N WINDS SHOULD TRAP-DOOR DOWN THE BACKSIDE OF THE EJECTING LOW THIS AFTN...SPEEDS AND SEAS INCREASING GEORGIA LEGS. SCA ALL WATERS OUTSIDE OF THE GALE WARNINGS. SEAS COULD BUILD AS HIGH AS 9-10 FT 15-30 NM OFF THE NRN CHARLESTON COUNTY BY 00Z/22. WINDS SHOULD BE ON THE DECREASE TONIGHT AND SAT OVER THE WATERS BUT SEAS WILL REMAIN ELEVATED THROUGH TUE. SMALL CRAFT ADVISORIES CONTINUE THROUGH SAT NIGHT IN THE NEARSHORE WATERS AND THROUGH MON EVENING OVER THE OFFSHORE. LAKE WINDS...RECENT OBSERVATION FROM EADYTOWN AND TIGHTENING OF THE PRES GRAD HAS PROMPTED AN ISSUANCE OF A LAKE WIND ADVISORY FOR LAKE MOULTRIE. WE RAN THE ADVISORY THROUGH TONIGHT AS THE GRAD REMAINS QUITE STRONG. && .TIDES/COASTAL FLOODING... HIGH TIDE AROUND 5-6 AM THIS MORNING FELL BELOW COASTAL FLOOD ADVISORY CRITERIA BUT RAIN LIKELY EXACERBATED SOME MINOR FLOODING. HIGH ASTRONOMICAL TIDES EXPECTED SAT THROUGH TUE MORNINGS. THE QUESTION IS WHEN WE EXPECT METEOROLOGICAL FACTORS TO RESULT IN ENOUGH POSITIVE ANOMALY TO PUSH TIDES ABOVE CRITICAL THRESHOLDS FOR SHALLOW COASTAL FLOODING. SAT MORNING HOLDS A CONSIDERABLE CHANCE ALONG THE SC COAST GIVEN CONTINUED NE WINDS AND SOME SWELL WAVE. SUN AND MON WILL BE CLOSE BUT WINDS WILL EITHER BE DUE S OR DUE N...NEITHER OF WHICH NORMALLY RESULTS IN MUCH OF A RESIDUAL. TUE MORNING WE COULD AGAIN BE PUSHING 7 FT AT CHS IF NE FLOW SETS UP AS FORECAST. && .EQUIPMENT... THERE WAS NO BE NO 12Z UPPER AIR FLIGHT THIS MORNING DUE TO HEAVY PCPN AND GROUND EQUIPMENT ISSUES. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...WIND ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR GAZ119. SC...LAKE WIND ADVISORY UNTIL 5 AM EST SATURDAY FOR SCZ045. WIND ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR SCZ048>051. MARINE...GALE WARNING UNTIL 11 PM EST THIS EVENING FOR AMZ352-354. GALE WARNING UNTIL 5 AM EST SATURDAY FOR AMZ330-350-374. && $$ 33/RVT/JRL ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 1256 AM EST FRI DEC 21 2007 .SYNOPSIS... SURFACE HIGH PRES WILL GIVE WAY TO AN APPROACHING UPPER-LEVEL DISTURBANCE WHICH WILL PASS THROUGH THE REGION AND MOVE OFF THE COAST EARLY FRI. THIS WILL ENHANCE A WEDGE PATTERN OVER THE CAROLINAS THAT SHOULD BREAK DOWN ON SUN AS A COLD FRONT APPROACHES FROM THE W. THE FRONT WILL MOVE OFF THE COAST EARLY MON...BUT UNSETTLED WEATHER COULD RETURN BY CHRISTMAS DAY AS ANOTHER UPPER- LEVEL DISTURBANCE IS POSSIBLE. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... SURFACE OBSERVATIONS INDICATE COLD AIR DAMMING IS BEGINNING TO TAKE SHAPE ACROSS INLAND AREAS WHILE COASTAL FRONTOGENESIS IS ONGOING OFFSHORE. THE INLAND WEDGE AND ASSOCIATED COASTAL FRONT WILL STRENGTHEN OVERNIGHT AS THERMAL GRADIENTS INTENSIFY DUE TO DIABATIC COOLING AND INCREASING BAROCLINICITY OFFSHORE NEAR THE WRN WALL OF THE GULF STREAM. OPTED TO RAISE LOW TEMPS A DEG OR TWO MOST AREAS BASED ON THE LATEST RUC-13 WET-BULB PROGNOSTICATIONS BUT STILL EXPECT TEMPS TO BOTTOM OUT IN THE UPR 40S ACROSS WELL INLAND WITH UPR 50S ALONG THE BEACHES. RAIN WILL BE LCLLY HEAVY AT TIMES THROUGH MID MORNING AS LOW-LVL CONVG ALONG THE WEDGE FRONT INCRS AND PWATS CLIMB ABOVE 1.25 INCHES. ALTHOUGH WDSPRD DEEP CONVECTION WILL BE LACKING... BUILDING ASTRONOMICAL TIDES MAY PEAK DURING A PERIOD OF MODERATE TO HEAVY RAINS ACROSS THE COASTAL COUNTIES EARLY FRI MRNG WHICH RAISES THE CONCERN FOR POSSIBLE FRESH WATER FLOODING PROBLEMS... ESPECIALLY IN THE DOWNTOWN CHARLESTON AREA. WILL DEFER THE DECISION FOR A FLOOD WATCH TO THE MIDNGT SHIFT AND MAINTAIN A MENTION OF POSSIBLE FLOODING PROBLEMS IN THE HAZARDOUS WEATHER OUTLOOK. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... THE LOW PRESSURE SYSTEM WILL SHIFT OFF THE GA/SC COASTLINE TODAY WITH RAIN CHANCES SUBSEQUENTLY DECREASING THROUGH THE DAY FROM SW TO NE. THE COASTAL LOW OFFSHORE WILL ACT TO AMPLIFY THE PERSISTENT INLAND SURFACE WEDGE. THICK CLOUD COVER AND RESIDUAL DRIZZLE DIABATICALLY ENHANCING THE COLD AIR DAMMING WILL CREATE CHILLY CONDITIONS FOR THE NORTHERN AND WESTERN COUNTIES. EXPECT HIGHS TO BE SUPPRESSED IN THE LOWER 50S NW ZONES...INCREASING TO THE LOWER TO MID 60S TOWARD THE S. A PINCHED GRADIENT ALONG THE CHARLESTON COUNTY COAST WILL LIKELY SUPPORT BREEZY CONDITIONS THERE FOR MUCH OF THE DAY. LAKE WINDS...A LAKE WIND ADVISORY MAY BE NEEDED FOR LAKE MOULTRIE ON FRIDAY...BUT MUCH WILL DEPEND ON WHERE EXACTLY THE SFC LOW DVLPS. WILL HOLD THE FCST JUST UNDER ADVISORY CRITERIA FOR NOW..BUT HEADLINE THAT AN ADVISORY MAY BE NEEDED. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... SOLID WEDGE WILL BE IN PLACE FRIDAY NIGHT INTO SATURDAY WITH NORTHEAST WINDS...COOL TEMPS...NOT A LOT OF SUN...AND EVEN A FEW LIGHT SHOWERS/DRIZZLE ...MAINLY IN THE NORTHEASTERN HALF OF THE CWA. WENT BELOW GUIDANCE FOR TEMPS ON SATURDAY. WINDS START TO VEER SATURDAY NIGHT AHEAD OF THE NEXT FRONT WITH A WARMER DAY SUNDAY ON SOUTH TO SOUTHWESTERLY WINDS. STILL...THE WEDGE MAY TRY TO HOLD ON FAR NORTH...BUT HAVE NOT GONE WITH THAT SOLUTION. AGAIN...THERE IS A SMALL CHANCE OF SHOWERS AHEAD OF THE FRONT. COLD FRONT GOES THROUGH SUNDAY NIGHT CAUSING THE WINDS TO COME AROUND TO THE NORTHWEST. THIS WILL INTRODUCE SOME DRYING WITH A BETTER CHANCE FOR SUNSHINE MONDAY. TEMPS WILL BE SEASONABLE. FORECAST BECOMES VERY UNCERTAIN FOR THE REMAINDER OF CHRISTMAS WEEK AS MODELS DIFFER SIGNIFICANTLY ON THE EVOLUTION OF A DEVELOP LOW. ONE SET OF SOLUTIONS DEVELOPS THE LOW OFF THE SOUTHEAST COAST AND SETS UP FOR A COOL CHRISTMAS WITH A CHANCE OF RAIN. ANOTHER SET DEVELOPS THE SYSTEM QUITE A BIT FURTHER WEST AND KEEPS US DRY UNTIL WEDNESDAY. FOR NOW...I WENT WITH CONTINUITY WHICH IS MORE PESSIMISTIC FOR CHRISTMAS DAY...BUT I DO NOT HAVE MUCH CONFIDENCE DUE TO THE DIVERGENCE OF MODEL SOLUTIONS. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... RNFL OCCURRING AT KSAV AT 06Z SHOULD CUT OFF FAIRLY QUICKLY BETWEEN 12Z AND 15Z...BUT CIGS LIKELY TO BE IN THE LIFR/IFR RANGE PRIOR TO SUNRISE SHOULD ONLY LIFT TO MVFR RANGES LATE MORNING INTO EARLY AFTN BEFORE CRATERING BACK TO LIFR/IFR CONDITIONS AGAIN LATER TODAY OR EARLY THIS EVENING. OCNLY HEAVY RNFL PRIOR TO 12Z WILL LIKELY LOWER VSBY AT SAVANNAH AOB 1 NM AT TIMES. AT KCHS...RAIN WAS JUST BEGINNING AT 06Z AND IT SHOULD PEAK BETWEEN 10Z AND 16Z WITH SOME LIGHT RAIN OR DRIZZLE LINGERING BEHIND THE MAIN SURGE OF RAINS WITH THE SHORTWAVE PASSAGE. BY LATE THIS AFTN... CIGS SHOULD BE IFR OR LESS WITH MVFR VSBYS. CIGS WILL PROBABLY BE LIFR OR LOWER AFTER SUNSET TONIGHT. VSBYS COULD BE REDUCED IN DRIZZLE AND FOG AS WELL. AT BOTH TAF SITES...N TO NE WINDS COULD BE GUSTY FROM THIS AFTN THROUGH THIS EVENING...HIGHEST AT KCHS. THIS IS DEPENDANT ON THE EVOLUTION OF A VERY COMPLEX SYNOPTIC REGIME. EXTENDED AVIATION OUTLOOK...LIFR OR LOWER CIGS AND REDUCED VSBYS IN FOG SAT MORNING...LIFTING TO MVFR CIGS FRI AFTN. LOW CIGS MAY REDEVELOP SAT NIGHT...ESPECIALLY AT KCHS. THERE SHOULD BE SOME IMPROVEMENT BY SUNDAY NIGHT AND MONDAY...BUT ANOTHER ROUND OF LOW CIGS IS POSSIBLE TUESDAY AND TUESDAY NIGHT. && .MARINE... THE PRESSURE GRADIENT IS SLOWLY INTENSIFYING ALONG THE SC COAST THIS EVNG BTWN HIGH PRES BUILDING INLAND AND A DVLPG COASTAL FRONT OFFSHORE. THE GRADIENT WILL CONTINUE TO PINCH ACROSS THE SC WTRS OVRNGT AND INTO FRI AS LOW PRES DVLPS OFF THE SC/GA COAST AND COLD AIR DAMMING STRENGTHS INLAND. A GALE WATCH HAS BEEN ISSUED FOR THE WATERS N OF EDISTO BEACH BEGINNING AROUND SUNRISE FRI AND CONTINUING THROUGH FRI NGT. THE WATCH MAY BE UPGRADED TO A GALE WARNING WITH THE EARLY MRNG FCST PKG. WHILE GALE FORCE WINDS ARE A POSSIBILITY IN THE CHARLESTON HARBOR...CONFIDENCE IS NOT HIGH ENOUGH ATTM TO JUSTIFY A GALE WATCH THERE. SMALL CRAFT ADVISORIES LOOK GOOD ACROSS THE REMAINDER OF THE MARINE AREA...ALTHOUGH THE START TIME FOR THE CHARLESTON HARBOR NEEDS TO BE MOVE UP TO FRI MRNG BASED ON CURRENT TRENDS. WINDS AOB 10 KT ACROSS THE GA NEARSHORE WTRS NEAR THE COASTAL FRONT BUT SHOULD BECOME N-NE 10-15 KT IN THE NEXT FEW HOURS AS LOW PRES DVLPS JUST OFFSHORE. PINNING DIRECTIONS IN THE GA WATERS WILL BE TRICKY UNTIL THE LOW PRES AREA CONSOLIDATES. WINDS WILL GO SOLIDLY NE ACROSS ALL WATERS BY FRI AFTN AS LOW PRES PULLS AWAY FROM THE AREA AND HIGH PRES WEDGE EXPANDS OFFSHORE. SEAS WILL BUILD QUICKLY NGT AND FRI AS NE WINDS INTENSIFY. FRIDAY NIGHT THROUGH TUESDAY...STRONGEST WINDS THROUGH THE PERIOD ARE EXPECTED FRIDAY NIGHT AND SATURDAY THANKS TO THE WEDGE. SCA CONDITIONS EXPECTED THROUGH A GOOD PART OF THE WEEKEND...AND EVEN INTO EARLY NEXT WEEK FOR THE OUTER GEORGIA WATERS. && .TIDES/COASTAL FLOODING... WILL WATCH FOR THE POTENTIAL OF SOME SHALLOW COASTAL FLOODING AROUND HIGH TIDE FRI MORNING IF HEAVY RAINFALL OCCURS. OTHERWISE... ASTRONOMICALLY HIGH TIDES EARLY SATURDAY MORNING AND AGAIN EARLY SUNDAY MORNING SETS US UP FOR THE POSSIBILITY ON MINOR COASTAL FLOODING EACH MORNING IN THE USUALLY VULNERABLE SPOTS. WIND MAY STILL BE ENOUGH OFFSHORE SATURDAY MORNING TO KEEP FROM HAVING MANY PROBLEMS...BUT A SLIGHT SHIFT TO MORE EASTERLY WOULD CHANGE THAT. ULTIMATELY...RESIDENTS IN THOSE FLOOD PRONE LOCATIONS NEED TO STAY TUNED. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 5 AM EST SATURDAY FOR AMZ330. SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 5 AM EST SUNDAY FOR AMZ352. GALE WATCH FROM 9 AM EST THIS MORNING THROUGH LATE TONIGHT FOR AMZ350. SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR AMZ350. SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 11 PM EST MONDAY FOR AMZ374. SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 5 AM EST SUNDAY FOR AMZ354. && $$ ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 603 PM EST FRI DEC 21 2007 .UPDATE/AVIATION... 1ST PD GRIDS WERE OBVIOUSLY CORRUPT AND RECREATED BUT DRIVING GIST OF EARLY UPDATE IS TO GET NEEDED DENSE FOG ADVISORY OUT ASAP. 22Z SFC ANALYSIS SHOWS SIG LL MSTR SITTING JUST SOUTH ACRS CNTRL IN/SW OH AND SLOWLY ADVTG NWD AND WILL LEAD TO SIGNIFICANT ADVECTIVE DENSE FOG OVERTOP EXISTING SNOWPACK AND COLD GROUND. HAVE CONSIDERABLE DOUBTS AS TO THE VALIDITY OF WMFNT MIXING THROUGH CWA BY MORNING AND IMPLIED SLOWLY RISING TEMPS ESP IN LIGHT OF RUC HOLDING LARGE SCALE PRES FALLS INADV OF SRN PLAINS CYCLONE WELL WEST OVERNIGHT BUT WILL LEAVE THAT FOR LIKELY ADDNL UPDATE LTR THIS EVENING W/BTR SHOT OF SHOWER DVLPMNT XPCD WRN HALF IN ASSOCN/W INCREASING LARGE SCALE ISENTROPIC ASCENT. XPC WIDESPREAD LIFR CONDS DVLPG QUICKLY THIS EVENING AND CONTINUING THROUGH MUCH OF SATURDAY. ASSUMING WARM SECTOR DEEPENS SUFFICIENTLY...SHLD SEE AN IMPROVEMENT TO IFR BY AFTN. && .SHORT TERM (TONIGHT AND SATURDAY)... FOCUS TONIGHT WILL BE ON ADVANCING AREA OF INCREASED DEWPOINTS AND ANTICIPATED LOWER VISIBILITIES IN FOG. LOCATIONS SEEING DEWPTS IN THE 34 DEGREE OR HIGHER RANGE TO THE SOUTH AND WEST ARE SEEING THE DENSER FOG HOLDING ON. RUC40/NAM12 ALL SHOWING SLOWER ARRIVAL OF HIGHER DEWPOINTS...WITH BEST ADVECTION NOT OCCURRING TILL CLOSER TO 6Z IN THE SW AND SPREADING NORTH OVERNIGHT. AS A RESULT WILL MAKE FURTHER ADJUSTMENTS AND SLOW DOWN ONSET OF FOG AND DRIZZLE. KIWX 88D SHOWS SOME LIGHT RETURNS THAT MAY REACH THE GROUND IN THE FORM OF A BIT OF DRIZZLE OR FLURRIES. SOME CONCERNS AS STUBBORN AS THE DRIER FLOW IS INTO THE AREA THAT FOG MAY STRUGGLE TO GET TOO FAR NORTH. WILL REMAIN OPTIMISTIC AS 925/850 MB WINDS RAMP UP LATER TONIGHT AND SHOULD ALLOW THE MSTR TO GET ON THE MOVE. ON SATURDAY...CONTINUATION OF SNOWMELT AND HIGHER DEWPTS WILL CONTINUE IN INCREASING S TO SW FLOW. NAM/GFS/SREF HAVE ALL TRENDED SLOWER WITH ARRIVAL OF PRECIP NOT BRINGING IN TILL LIKELY OUTSIDE THIS PERIOD. DID NOT WANT TO DROP ALL POPS AT THIS POINT SO WENT DRASTIC DOWNWARD TREND AND REPOSITION OF BEST CHC FOR ANY PRECIP BY LATE AFTERNOON. WITH SLOWER ARRIVAL OF PRECIP...WARMER TEMPS MAY BE POSSIBLE ESPECIALLY IF FOG CAN LIFT OUT SOONER OR DOESN`T MATERIALIZE AS MUCH. FOR NOW HAVE LEFT THINGS ALONE TEMP WISE. && .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... SATURDAY NIGHT THROUGH SUNDAY AMPLIFIED PATTERN ACROSS THE CENTRAL AND EASTERN CONUS WITH DEEP TROUGH OVER THE CENTRAL CONUS AND RIDGING ACROSS THE EAST. SFC WAVE MOVING UP FROM MID MS VALLEY TOWARDS LAKE MICHIGAN BY LATE SATURDAY NIGHT INTO EARLY SUNDAY. SFC LOW MOVES THRU THE LP OF MICHIGAN AN NORTH INTO CENTRAL ONTARIO BY SUNDAY AFTERNOON...BEFORE PULLING NORTHEAST INTO NORTHERN QUEBEC BY EARLY MONDAY. THERMAL PROFILE ACROSS THE REGION SUGGESTS ALL RAIN THRU THE OVERNIGHT BEFORE STARTING THE TRANSITION PERIOD AROUND DAYBREAK SUNDAY. MODELS HAVING BEEN SLOWING THE SYSTEM DOWN AND HAVE THEREFORE SLOWED THE PRECIP CHANGEOVER DOWN SOME AS WELL...AS THE H850 TEMPS DROP FROM +5 C TO BELOW 0C ACROSS THE ENTIRE REGION BETWEEN 12-15Z. ANY WRAP AROUND OR LAKE ENHANCED PRECIP WILL BE SNOW THEN THROUGH THE LATE MORNING INTO THE AFTERNOON WITH VERY STRONG CAA INTO THE REGION. TEMPS WILL CONTINUE TO DROP FROM LATE SATURDAY NIGHT THRU SUNDAY NIGHT...FROM 40S LATE SATURDAY NIGHT INTO THE 20S BY SUNDAY AFTERNOON...AND TEENS FOR LOWS OVERNIGHT INTO EARLY MONDAY. SIGNIFICANT AMOUNTS OF MOISTURE FOR THE SYSTEM TO WORK WITH WITH PWATS ABOVE 1 INCH EARLY SUNDAY...LIQUID QPF AMOUNTS WILL PUSH .5 INCHES FOR MOST OF THE AREA...BUT VERY LITTLE SNOW ACCUMS EXPECTED THRU THE PERIOD. MAINLY WITH LAKE ENHANCED OR LAKE EFFECT ACROSS THE FAR NW PORTIONS OF THE AREA AND ACROSS THE FAR NORTHERN TIER OF COUNTIES AS THE FLOW ACROSS THE LAKE BECOME MORE WESTERLY WITH TIME...MAYBE AN INCH OR TWO. UPPER LEVEL LOW STARTS TO PUSH INTO THE GREAT LAKES EARLY SUNDAY AND THRU THE DAY...VERY TIGHT PRESSURE GRADIENT ACROSS THE REGION WITH NORTHWEST/WEST FLOW THROUGH THE DAY. GUSTY WINDS WILL INCREASE FROM EARLY SUNDAY THROUGH SUNDAY AFTERNOON. LAKE EFFECT SNOW ACROSS THE NORTHERN TIER OF THE CWA WILL CONTINUE TO BE A POSSIBILITY WITH DELTA T/S REACHING LEVELS OF -15 OR MORE BY SUNDAY EVENING. MONDAY THROUGH FRIDAY SPLIT FLOW ACROSS THE WEST BECOMES MORE CONFLUENT ACROSS THE EASTERN CONUS...UPPER LEVEL LOW PUSHING EAST THRU THE ST LAW RVR VALLEY WITH ANOTHER SW CONUS SHRTWV PULLING OUT AND WEAKENING AS IT MOVES TO THE NORTHEAST. LARGE SFC HIGH ENTRENCHED ACROSS THE GREAT LAKES/OH AND MS VALLEYS INTO TUESDAY...WITH SOME UPPER LEVEL RIDGING BUILDING ACROSS THE REGION TUESDAY INTO WEDNESDAY WITH ANOTHER UPPER LEVEL LOW OVER THE SW CONUS. BELOW NORMAL TEMPS EXPECTED MONDAY...SLIGHTLY WARMER AND NEAR SEASONAL VALUES OF LOWER TO MID 30S FOR HIGHS. DRY THRU THE PERIOD...A SMALL CHANCE OF LAKE EFFECT ACROSS THE FAR NORTH EARLY MONDAY. MID RANGE MODELS HAVING SOME ISSUES THRU THE END OF THE PERIOD...SIGNIFICANT DISAGREEMENTS WITH RESPECT TO THE STRENGTH AND TIMING BUT THE LATEST GFS AND THE ENSEMBLE MEANS HAVE BEEN SHOWING SOME SIGNIFICANT WINTRY POTENTIAL TOWARDS THE END OF THE MONTH. FIRST POTENTIAL SIGNIFICANT SYSTEM WILL BE WEDNESDAY NIGHT INTO THURSDAY TIMEFRAME. CUT-OFF LOW PUSHES EAST INTO THE RIDGE...POSSIBLE NEG TILT WITH SFC LOW MOVING FROM THE LOWER MS VALLEY INTO THE REGION. MOISTURE SHOULD NOT BE A CONCERN WITH THE GULF APPEARING TO BE OPEN...PWATS AT OR MORE THAN DOUBLE NORMAL FOR THE TIME OF YEAR. THE TRACK STILL UNCERTAIN...WILL LIMIT THE DETAILS...BUT CURRENT BUFKIT AND MODEL THERMAL PROFILES WOULD SUGGEST ALL SNOW. HAVE UPPED POPS TO 50 THRU THE PERIOD WITH HIGHER CONFIDENCE THAT A SYSTEM WILL BE THERE...BUT LOWER CONFIDENCE ON TRACK AND P-TYPE AS THE MODELS THIS SEASON HAVE HAD SOME SIGNIFICANT SHIFTS OVER TIME OF UP TO 300-500 MILES. ANOTHER DIGGING UPPER LEVEL LOW INTO THE SOUTHWEST LATE IN THE WEEK...THURSDAY INTO FRIDAY...WILL START KICK OUT AND WILL ALLOW FOR THE SECOND POTENTIAL WINTER SYSTEM BY THE WEEKEND. PRECIP COULD START AS SOON AS FRI NIGHT/SATURDAY...WITH TRACK AND P-TYPE HIGHLY UNCERTAIN...STILL 6-7 DAYS OR MORE OUT MUCH TO CHANGE MOST LIKELY. STRONG MODEL SUPPORT FROM THE GFS ENSEMBLES. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...FISHER LONG TERM...SCHOTT UPDATE/AVIATION...HOLSTEN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 357 PM EST FRI DEC 21 2007 .SHORT TERM (TONIGHT AND SATURDAY)... FOCUS TONIGHT WILL BE ON ADVANCING AREA OF INCREASED DEWPOINTS AND ANTICIPATED LOWER VISIBILITIES IN FOG. LOCATIONS SEEING DEWPTS IN THE 34 DEGREE OR HIGHER RANGE TO THE SOUTH AND WEST ARE SEEING THE DENSER FOG HOLDING ON. RUC40/NAM12 ALL SHOWING SLOWER ARRIVAL OF HIGHER DEWPOINTS...WITH BEST ADVECTION NOT OCCURRING TILL CLOSER TO 6Z IN THE SW AND SPREADING NORTH OVERNIGHT. AS A RESULT WILL MAKE FURTHER ADJUSTMENTS AND SLOW DOWN ONSET OF FOG AND DRIZZLE. KIWX 88D SHOWS SOME LIGHT RETURNS THAT MAY REACH THE GROUND IN THE FORM OF A BIT OF DRIZZLE OR FLURRIES. SOME CONCERNS AS STUBBORN AS THE DRIER FLOW IS INTO THE AREA THAT FOG MAY STRUGGLE TO GET TOO FAR NORTH. WILL REMAIN OPTIMISTIC AS 925/850 MB WINDS RAMP UP LATER TONIGHT AND SHOULD ALLOW THE MSTR TO GET ON THE MOVE. ON SATURDAY...CONTINUATION OF SNOWMELT AND HIGHER DEWPTS WILL CONTINUE IN INCREASING S TO SW FLOW. NAM/GFS/SREF HAVE ALL TRENDED SLOWER WITH ARRIVAL OF PRECIP NOT BRINGING IN TILL LIKELY OUTSIDE THIS PERIOD. DID NOT WANT TO DROP ALL POPS AT THIS POINT SO WENT DRASTIC DOWNWARD TREND AND REPOSITION OF BEST CHC FOR ANY PRECIP BY LATE AFTERNOON. WITH SLOWER ARRIVAL OF PRECIP...WARMER TEMPS MAY BE POSSIBLE ESPECIALLY IF FOG CAN LIFT OUT SOONER OR DOESN`T MATERIALIZE AS MUCH. FOR NOW HAVE LEFT THINGS ALONE TEMP WISE. && .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... SATURDAY NIGHT THROUGH SUNDAY AMPLIFIED PATTERN ACROSS THE CENTRAL AND EASTERN CONUS WITH DEEP TROUGH OVER THE CENTRAL CONUS AND RIDGING ACROSS THE EAST. SFC WAVE MOVING UP FROM MID MS VALLEY TOWARDS LAKE MICHIGAN BY LATE SATURDAY NIGHT INTO EARLY SUNDAY. SFC LOW MOVES THRU THE LP OF MICHIGAN AN NORTH INTO CENTRAL ONTARIO BY SUNDAY AFTERNOON...BEFORE PULLING NORTHEAST INTO NORTHERN QUEBEC BY EARLY MONDAY. THERMAL PROFILE ACROSS THE REGION SUGGESTS ALL RAIN THRU THE OVERNIGHT BEFORE STARTING THE TRANSITION PERIOD AROUND DAYBREAK SUNDAY. MODELS HAVING BEEN SLOWING THE SYSTEM DOWN AND HAVE THEREFORE SLOWED THE PRECIP CHANGEOVER DOWN SOME AS WELL...AS THE H850 TEMPS DROP FROM +5 C TO BELOW 0C ACROSS THE ENTIRE REGION BETWEEN 12-15Z. ANY WRAP AROUND OR LAKE ENHANCED PRECIP WILL BE SNOW THEN THROUGH THE LATE MORNING INTO THE AFTERNOON WITH VERY STRONG CAA INTO THE REGION. TEMPS WILL CONTINUE TO DROP FROM LATE SATURDAY NIGHT THRU SUNDAY NIGHT...FROM 40S LATE SATURDAY NIGHT INTO THE 20S BY SUNDAY AFTERNOON...AND TEENS FOR LOWS OVERNIGHT INTO EARLY MONDAY. SIGNIFICANT AMOUNTS OF MOISTURE FOR THE SYSTEM TO WORK WITH WITH PWATS ABOVE 1 INCH EARLY SUNDAY...LIQUID QPF AMOUNTS WILL PUSH .5 INCHES FOR MOST OF THE AREA...BUT VERY LITTLE SNOW ACCUMS EXPECTED THRU THE PERIOD. MAINLY WITH LAKE ENHANCED OR LAKE EFFECT ACROSS THE FAR NW PORTIONS OF THE AREA AND ACROSS THE FAR NORTHERN TIER OF COUNTIES AS THE FLOW ACROSS THE LAKE BECOME MORE WESTERLY WITH TIME...MAYBE AN INCH OR TWO. UPPER LEVEL LOW STARTS TO PUSH INTO THE GREAT LAKES EARLY SUNDAY AND THRU THE DAY...VERY TIGHT PRESSURE GRADIENT ACROSS THE REGION WITH NORTHWEST/WEST FLOW THROUGH THE DAY. GUSTY WINDS WILL INCREASE FROM EARLY SUNDAY THROUGH SUNDAY AFTERNOON. LAKE EFFECT SNOW ACROSS THE NORTHERN TIER OF THE CWA WILL CONTINUE TO BE A POSSIBILITY WITH DELTA T/S REACHING LEVELS OF -15 OR MORE BY SUNDAY EVENING. MONDAY THROUGH FRIDAY SPLIT FLOW ACROSS THE WEST BECOMES MORE CONFLUENT ACROSS THE EASTERN CONUS...UPPER LEVEL LOW PUSHING EAST THRU THE ST LAW RVR VALLEY WITH ANOTHER SW CONUS SHRTWV PULLING OUT AND WEAKENING AS IT MOVES TO THE NORTHEAST. LARGE SFC HIGH ENTRENCHED ACROSS THE GREAT LAKES/OH AND MS VALLEYS INTO TUESDAY...WITH SOME UPPER LEVEL RIDGING BUILDING ACROSS THE REGION TUESDAY INTO WEDNESDAY WITH ANOTHER UPPER LEVEL LOW OVER THE SW CONUS. BELOW NORMAL TEMPS EXPECTED MONDAY...SLIGHTLY WARMER AND NEAR SEASONAL VALUES OF LOWER TO MID 30S FOR HIGHS. DRY THRU THE PERIOD...A SMALL CHANCE OF LAKE EFFECT ACROSS THE FAR NORTH EARLY MONDAY. MID RANGE MODELS HAVING SOME ISSUES THRU THE END OF THE PERIOD...SIGNIFICANT DISAGREEMENTS WITH RESPECT TO THE STRENGTH AND TIMING BUT THE LATEST GFS AND THE ENSEMBLE MEANS HAVE BEEN SHOWING SOME SIGNIFICANT WINTRY POTENTIAL TOWARDS THE END OF THE MONTH. FIRST POTENTIAL SIGNIFICANT SYSTEM WILL BE WEDNESDAY NIGHT INTO THURSDAY TIMEFRAME. CUT-OFF LOW PUSHES EAST INTO THE RIDGE...POSSIBLE NEG TILT WITH SFC LOW MOVING FROM THE LOWER MS VALLEY INTO THE REGION. MOISTURE SHOULD NOT BE A CONCERN WITH THE GULF APPEARING TO BE OPEN...PWATS AT OR MORE THAN DOUBLE NORMAL FOR THE TIME OF YEAR. THE TRACK STILL UNCERTAIN...WILL LIMIT THE DETAILS...BUT CURRENT BUFKIT AND MODEL THERMAL PROFILES WOULD SUGGEST ALL SNOW. HAVE UPPED POPS TO 50 THRU THE PERIOD WITH HIGHER CONFIDENCE THAT A SYSTEM WILL BE THERE...BUT LOWER CONFIDENCE ON TRACK AND P-TYPE AS THE MODELS THIS SEASON HAVE HAD SOME SIGNIFICANT SHIFTS OVER TIME OF UP TO 300-500 MILES. ANOTHER DIGGING UPPER LEVEL LOW INTO THE SOUTHWEST LATE IN THE WEEK...THURSDAY INTO FRIDAY...WILL START KICK OUT AND WILL ALLOW FOR THE SECOND POTENTIAL WINTER SYSTEM BY THE WEEKEND. PRECIP COULD START AS SOON AS FRI NIGHT/SATURDAY...WITH TRACK AND P-TYPE HIGHLY UNCERTAIN...STILL 6-7 DAYS OR MORE OUT MUCH TO CHANGE MOST LIKELY. STRONG MODEL SUPPORT FROM THE GFS ENSEMBLES. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...FISHER LONG TERM...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1214 PM EST FRI DEC 21 2007 .UPDATE... UPDATED GRIDS/ZONES EARLIER TO SLOW DOWN ARRIVAL OF FOG BASED ON TRENDS AND RUC40 DATA. HIGHER DEWPTS SLOWLY COMING IN BUT LOOK TO BE DELAYED UNTIL LATER TODAY INTO TONIGHT. HAVE PUSHED BACK MENTION OF DENSE FOG TO TONIGHT WHEN MOISTURE WILL INCREASE DRAMATICALLY AS LOW LEVEL FLOW BEGINS TO INCREASE. HAVE JUST WENT PATCHY DENSE AT THIS POINT. TEMPS STILL LOOK OK FOR NOW SO HAVE LEFT THEM AND THE REMAINDER OF THE GRIDS ALONE. && .AVIATION... AS MENTIONED IN UPDATE...HAD PREVIOUSLY SLOWED DOWN ARRIVAL OF MAINLY LOWER VSBYS. WILL NEED TO CONTINUE THIS TREND WITH GENERAL MVFR VSBY/IFR CIGS STARTING THE PERIOD THEN DROPPING TO LIFR CONDITIONS BY EARLY EVENING AT KSBN. MAY BE A BIT SLOWER ARRIVAL AT KFWA. ONCE THESE ARRIVE...LITTLE OVERALL CHANGE EXPECTED UNTIL SATURDAY AS WINDS BEGIN TO INCREASE AND ALLOW FOR BETTER MIXING AND INCREASE IN HGTS/VSBYS. && .PREV DISCUSSION... /ISSUED 640 AM EST FRI DEC 21 2007/ SHORT TERM... TODAY AND TONIGHT LOTS OF LOW LEVEL MOISTURE...DRIZZLE AND FOG IS THE STORY FOR TODAY AND TONIGHT. WARM AIR ADVECTION WILL CONTINUE TODAY. THE SNOW COVER ACROSS THE AREA WILL KEEP TEMPERATURES NEAR THE SURFACE COOLER THAN UP ABOVE...SETTING UP A DECENT INVERSION TODAY. THIS WILL HELP TO KEEP THE MOISTURE FROM THE MELTING SNOW TODAY TRAPPED NEAR THE SURFACE...RESULTING IN FOG ACROSS THE AREA. WITH DECENT MOISTURE UP TO ABOUT 5KFT TO 7KFT...DRIZZLE IS ALSO POSSIBLE. THE LARGE DEWPOINT DEPRESSIONS IN THE CWA THIS NIGHT HAVE KEPT THE LIGHT RAIN/DRIZZLE OFF TO THE WEST...BUT THE ATMOSPHERE IS EXPECTED TO BECOME MORE AND MORE SATURATED AS THE HOURS PASS BY...AND EVENTUALLY THE LOWER CEILINGS AND VISIBILITIES WILL MOVE INTO THE CWA. JUST WHEN THESE LOWER CONDITIONS WILL MOVE IN AND WHERE THEY WILL DROP THE MOST HAS BEEN THE TRICKIEST PART OF THE FORECAST FOR TODAY. VISIBILITIES ARE STILL UP ACROSS THE CWA SO HAVE SLOWED DOWN THE FOG MOVING INTO/FORMING IN THE AREA. ALSO TO NOTE WHERE TEMPERATURES ARE AT FREEZING AND BELOW...MAINLY IN THE NORTHEASTERN TO EASTERN PARTS OF THE CWA...EARLY THIS MORNING ANY DRIZZLE WILL BE FREEZING DRIZZLE. BUT TEMPERATURES ARE EXPECTED TO WARM UP ABOVE THE FREEZING MARK ACROSS THE ENTIRE CWA BY MID MORNING. TRICKY YET AS TO HOW FAR EASTWARD AREAS OF DENSE FOG COULD MAKE IT...BUT FOR RIGHT NOW JUST HAVE THE WESTERN PART OF THE CWA SEEING AREAS OF DENSE FOG FORM THIS MORNING. THE WARM AIR ADVECTION WILL CONTINUE THROUGH THIS EVENING AND TONIGHT...RESULTING IN NON DIURNAL TEMPERATURES FOR TONIGHT. TEMPERATURES WILL EITHER REMAIN FAIRLY STEADY OR SLOWLY INCREASE A FEW DEGREES THROUGHOUT THE NIGHT. THEREFORE THIS DAY/S LOW TEMPERATURES ARE EXPECTED TO OCCUR EARLY THIS MORNING. THE ATMOSPHERE IS GOING TO REMAIN FAIRLY WELL SATURATED IN THE LOWER LEVELS THROUGH TONIGHT WITH THE LOW LEVEL INVERSION CONTINUING THROUGH TONIGHT. THEREFORE AREAS OF FOG AND DRIZZLE ARE CONTINUED FOR TONIGHT. LONG TERM... SATURDAY THROUGH THURSDAY MAIN EMPHASIS ON WEST COAST SYSTEM TO ARRIVE SAT NIGHT. NAM FAVORED SOLN WITH INITIALIZATION OF COMPLEX WESTERN TROF WITH ALBERTA ENERGY AND STRATOSPHERIC INTRUSION ACRS WCENTL NV/SOCAL AT 00 UTC. RATHER BROAD TONGUE OF 40F PLUS DEWPOINTS ALREADY POISED NORTH OF OHIO RIVER AND WITH SEVERAL HOURS OF ADDITIONAL SNOWMELT AND ADVECTIVE COMPONENT WILL AID IN TOTAL MOISTURE INCREASE AHEAD OF STRONG FULL LATITUDINAL SYSTEM THAT WILL UNDERGO RAPID INTENSIFICATION. FROM F36-60 RAPID ML HEIGHT FALLS ON ORDER OF 160-190/12 HRS REFLECTS NEAR BOMBO SURFACE CYCLOGENESIS AS RED RIVER VLY SFC LOW AT F36/12 UTC SAT NEAR RED RIVER VLY TX SURGES NE TO 1001 MB CNTL IL THEN TO 987MB OVER CNTL UP. PWAT APPROACH 1 INCH WITH 7.5-7.8 G/KG IN 1000-850MB LAYER WITH TREMENDOUS LOW LEVEL KINEMATICS UPPED POPS TO 90 PERCENT WITH STRONG SIGNALS/MOISTURE...CONSIDERED ISOLD TSRA THOUGH OVERALL CHANCES SLIGHT. DRY SLOT BEHIND FRONT QUICKLY BRING POPS DOWN TO CHC CATEGORY...AND PTYPE QUICKLY TO SNOW LATE SATURDAY NIGHT WEST IN STRONG/DEEP CAA WITH ABRUPT CHANGEOVER THOUGH LITTLE IF ANY ACCUM EXPECTED. RAMPED WINDS SAT THRU SUN NIGHT...ESP SUN GIVEN INTENSITY OF SFC LOW. BEYOND LITTLE CHANGE MADE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR LMZ043-046. && $$ SHORT TERM...LOTHAMER LONG TERM...MURPHY AVIATION/UPDATE...FISHER in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 530 AM CST FRI DEC 21 2007 .UPDATED FOR THE AVIATION FORECAST... .SYNOPSIS... LOW LAYERS SATURATED THIS MORNING WITH LIFR CIGS/VSBYS ALONG AND EAST OF AXA-BNW-LWD LINE AT 09Z. SYS IN QUESTION FOR WEEKEND PUSHING THROUGH WRN CONUS. WEAK SHRT WVS NOTED OVER SD AND UPR MS RIVER VALLEY WITH PATCHY MID/HIGH CLOUDS ABOVE...BUT LITTLE OTHER FORCING IN PLACE FOR THE TIME BEING. && .DISCUSSION... IMMEDIATE CONCERN WILL BE FATE OF DENSE FOG ADVY. WILL LEAVE IT GOING FCST AREA WIDE THROUGH 15Z. VSBYS NOT TOO LOW IN WRN SECTIONS AT 09Z...BUT WITH WEAK SELY FLOW AND DIMINISHING MID/HIGH CLOUDS FEEL POTENTIAL IS CERTAINLY THERE FOR DENSE FOG DEVELOPMENT OVER ENTIRE AREA. WITH PLENTY OF STRATUS UPSTREAM OVER MO...CANNOT SEE ANY REASON WHY LOW VSBYS WILL NOT CONTINUE ERN SECTIONS SO HAVE ADVY GOING THERE TOO TIL 18Z. ATTENTION THEN TURNS TO SIGNIFICANT WEEKEND SYS. NAM/GFS BOTH KEEP AREA LOCKED INTO STRATUS TONIGHT WITH COLUMN NOT REALLY TRYING TO SATURATE UNTIL 09Z AND AFTER. HAVE LOWERED MEASURABLE POPS THROUGH AT LEAST MIDNIGHT WITH FOG AND TRACE MENTIONS OF EITHER DRZL OR FRZG DRZL DEPENDING ON SFC TEMPS WHICH GENERALLY FOLLOWED A BLEND OF AVAILABLE GUIDANCE AND LOW LEVEL TEMPS. TRANSITIONED TO HIGHER POPS BEFORE DAYBREAK AND RAIN OR SNOW WORDING. FORECAST INTO SAT WAS BASICALLY A BLEND OF 00Z GFS/12Z ECMWF. AIRMASS SATURATES WITH ALL SNOW NWRN HALF AND RAIN CHANGING TO SNOW SERN HALF. SFC AND WARM LAYER TEMPS FALL AT GENERALLY THE SAME TIME SO ALTHOUGH THERE COULD BE A BRIEF PERIOD OF SLEET AS WARM LAYERS DIPS TO 1-3C...DO NOT FEEL IT WILL BE LONG ENOUGH OR SIGNIFICANT ENOUGH TO MENTION. DID PUSH START OF WATCH BACK TO 18Z HOWEVER AS BEST UVM DOES NOT ARRIVE UNTIL THAT TIME...AND STILL HAVE RAIN MENTION SE. DENDRITIC LAYER FORCING INCREASES DURING THE AFTERNOON IN 300K ISENT SFC AND H5/H6 PRES LAYER. EXPECT RELATIVELY NARROW SW-NE RIBBON OF SNOW TO DEVELOP INTO CENTRAL IA...THEN MORE WIDESPREAD AND INTENSE UVM CLIPPING SERN PORTIONS AS PRIMARY SHRT WV EJECTS INTO MID MS VALLEY. SNOWFALL INTENSITIES REALLY INCREASE AS FORCING MOVES INTO DVN AREA DURING THE EARLY EVENING. MOISTURE TRANSPORT...FRONTOGENETICAL FORCING AND LOWERING STATIC STABILITIES ALL COME TOGETHER DURING THIS TIME FRAME. CONSIDERING THIS AMOUNT OF FORCING IN DENDRITIC LAYER...HAVE SNOW AMOUNTS IN HIGH END OF COBB OUTPUT WITH AMOUNTS RANGING FROM 1 FAR NW TO 6 FAR SE WHERE UVM IS BEST. QUICK LOOK AT 00Z ECMWF QPF IS NOW HIGHER...BUT LATER SWITCH TO SNOW MAY DIMINISH AMOUNTS SOMEWHAT SE SO PRETTY MUCH STUCK WITH AFOREMENTIONED THINKING FOR THE TIME BEING ALTHOUGH THIS TREND WILL HAVE TO BE WATCHED. THESE AMOUNTS DO NOT JUSTIFY WATCH BY THEMSELVES...BUT WITH BLOWING SNOW CONSIDERED WILL LEAVE HEADLINE GOING AS IS. SOMEWHAT LOW CONFIDENCE ON WRN EDGES...BUT WITH BLOWING SNOW POTENTIAL DID NOT CHANGE ANYTHING AT THE MOMENT BESIDES ALTERATION OF START TIME AND EXTENSION TIL 12Z SUN. ALTHOUGH CONFIDENCE NOT HIGH ENOUGH TO BOOST INTO BLIZZARD WATCH YET...WILL MENTION NEAR BLIZZARD CONDITIONS IN TEXT OF WSW. AS SYS MATURES AROUND 00Z...VSBYS COULD DROP TO 1/4MI WITH WINDS GUSTING TO NEAR 35 MPH. SNOW WILL QUICKLY DIMINISH IN OUR AREA DURING THE EVENING...BUT BLOWING SNOW POTENTIAL CONTINUES OVERNIGHT HENCE WATCH EXTENSION. WINDS SHOULD GUST WELL THROUGH THE 20S FOR AN EXTENDED PERIOD. RAW MODEL AND SREF TEMPS SUGGEST GUIDANCE IS TOO WARM TODAY AND COOL TONIGHT WITH BLANKET OF STRATUS SO HAVE GONE BELOW AND ABOVE MOS TODAY AND TONIGHT RESPECTIVELY. WENT ABOVE SAT MORNING BEFORE TEMPS START CRASHING WITH QUICK SURGE OF WAA. EXPECT LITTLE REBOUND SUN WITH WRAP AROUND STRATUS SO HAVE UNDERCUT GUIDANCE SUN. && .AVIATION...21/12Z LIFR CONDITIONS TO CONTINUE THROUGH 15Z AT ALL TERMINAL SITES...WITH THE EASTERN TERMINALS STILL SEEING LIFR CONDITIONS THROUGH 18Z. VSBYS MAY IMPROVE THROUGHOUT THE AFTERNOON INTO THE IFR/MVFR RANGE...HOWEVER CEILINGS ARE STILL EXPECTED TO REMAIN LOW. ALL MODELS INDICATING A DECENT LAYER OF SATURATION THAT PERSISTS THROUGHOUT THE LOWER LEVELS THROUGH THE DAY. HAVE TRENDED TOWARD A SLIGHTLY INCREASING VSBYS/CIGS IN THE AFTERNOON...AS RUC HINTS A BRIEF TIME PERIOD OF SOME DRIER AIR PUSHING INTO THE WESTERN/SOUTHERN TAF SITES. HOWEVER AM SOMEWHAT SKEPTICAL...AND ALL AREAS MAY REMAIN SOCKED IN WITH FOG/LOW STRATUS THROUGH THE DAY WITH SOUTHEAST FLOW CONTINUING TO ADVECT MOISTURE FROM MISSOURI/FOG AREA INTO THE CWA. && DMX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVY ENTIRE AREA THROUGH 15Z...AND ALONG AND EAST OF ALGONA-WEBSTER CITY-DES MOINES-CORYDON LINE TIL 18Z. WINTER STORM WATCH 18Z SAT-12Z SUN ALONG AND EAST OF FOREST CITY-WEBSTER CITY-WINTERSET-CHARITON-CORYDON LINE. && $$ SMALL/ALBRECHT ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 553 PM MST FRI DEC 21 2007 .AVIATION...AS OF 00Z...A LOW LEVEL STRATUS CLOUD DECK HAS MOVED OVER THE WESTERN HALF OF THE CWA BRINGING MVFR CONDITIONS...WHILE VFR CONDITIONS WILL LAST A FEW MORE HOURS OVER THE EASTERN HALF OF THE CWA. LIGHT SNOW HAS BEGUN TO FALL OVER EAST CENTRAL AND NORTHEASTERN COLORADO. SNOW WILL GRADUALLY SPREAD ACROSS THE CWA FROM THE NORTHWEST TOWARD THE SOUTHEAST. WINDS FROM THE NORTH AND NORTHWEST AT 35 TO 30 MPH...GUSTING UP TO 40 MPH AT TIMES...WILL ACCOMPANY THE SNOW FALL THROUGHOUT MOST OF THE TAF PERIOD. AFTER 06Z...WHEN THE SNOWFALL BECOMES MORE WIDESPREAD ACROSS THE AREA...BLOWING SNOW WILL LIKELY RESULT IN PERIODS OF VLIFR CONDITIONS. BY 18Z...THE SNOW AND WINDS WILL DIMINISH AS CEILINGS BEGIN TO SCATTER OUT. && .PREV DISCUSSION... /ISSUED 200 PM MST FRI DEC 21 2007/ .DISCUSSION...FORECAST CONCERNS ARE ON WINDS AND SNOW TONIGHT THROUGH EARLY IN THE DAY SATURDAY. MORE SNOW EXPECTED AGAIN CHRISTMAS DAY INTO WEDNESDAY WITH ANOTHER THURSDAY INTO FRIDAY. .SHORT TERM (TONIGHT-MONDAY NIGHT)... TONIGHT-SATURDAY...UPPER TROUGH AXIS CURRENTLY EXTENDING ALONG THE CONTINENTAL DIVIDE WILL MOVE ACROSS THE AREA OVERNIGHT AND BY 18Z BE EAST OF THE AREA. THE COMBINATION OF 850-500MB MOISTURE/MID LEVEL FRONTOGENESIS AND 250 JET DIVERGENCE WILL FAVOR HIGHEST POPS ACROSS SOUTHERN 2/3 OF THE AREA...HIGHEST ACROSS THE FAR SOUTH. TOTAL ACCUMULATIONS IN THIS AREA WILL RANGE FROM 1 TO 3 INCHES...HIGHEST SOUTH. LATEST NAM/RUC SHOWING SOME ORGANIZATION TO THE SNOW ACROSS INTERSTATE 70 WITH A LULL IN SNOW IN THE DOWNSLOPE AREAS OF CHEYENNE COUNTY COLORADO AND WALLACE KS. WILL ISSUE A SNOW AND BLOWING SNOW ADVISORY AS A RESULT FROM 03Z TONIGHT THROUGH 18Z SATURDAY. ELSEWHERE...WILL UPDATE THE HWO TO TALK ABOUT THE SNOW AND POTENTIAL FOR BLOWING SNOW OUTSIDE THE ADVISORY AREA. WILL KEEP SOME POPS MENTIONED ACROSS THE FAR EAST/SOUTHEAST THROUGH 18Z SATURDAY GIVEN TIMING DIFFERENCES AMONGST THE MODELS WITH REGARD TO HOW FAST THE SYSTEM LEAVES THE AREA. GFS/09Z SREF THE SLOWER OF THE MODELS WITH THE NAM/NGM A BIT QUICKER. AFTER 18Z IT SHOULD BE PRETTY MUCH OVER WITH...EXCEPT THE WIND. ONCE THE SNOW ENDS WE STILL HAVE TO DEAL WITH STRONG WINDS JUST OFF THE SURFACE AND INCREASING SUNSHINE AS THE SYSTEM MOVES EAST. QUESTION BECOMES WHETHER THE WIND WILL FULLY MIX TO THE SURFACE GIVEN EXISTING SNOW COVER AND EXPECTED LIGHT ACCUMULATIONS. FOR NOW WILL NOT ISSUE A WIND ADVISORY FOR THE 18Z- 22Z TIME FRAME GIVEN THE CONCERN LISTED ABOVE. SATURDAY NIGHT-SUNDAY...WILL HAVE A BRIEF PERIOD OF CLEAR SKIES BEFORE MID AND UPPER LEVEL MOISTURE SPREADS ACROSS THE AREA FROM THE NORTHWEST AFTER MIDNIGHT AS ANOTHER QUICK MOVING SYSTEM MAKES ITS WAY TOWARD THE AREA. COLUMN STARTS TO SATURATE IN THE 850-500 LAYER DURING THE DAY SUNDAY FROM NORTHWEST TO SOUTHEAST. DESPITE THE INCREASE IN MOISTURE DYNAMICS AND LIFT ARE LACKING...THUS WILL MAINTAIN A NO POP FORECAST. SUNDAY NIGHT-MONDAY NIGHT...WELL ORGANIZED UPPER DISTURBANCE EMBEDDED IN A DEEP AND COMPACT TROUGH WILL MOVE SOUTH THROUGH THE FRONT RANGE AND EASTERN PLAINS OF COLORADO INTO SOUTHWEST/SOUTH CENTRAL KANSAS BY THE END OF THE PERIOD. LOOKS LIKE THIS SYSTEM WILL SLIDE JUST FAR ENOUGH WEST AND SOUTH OF THE AREA TO KEEP SILENT POPS IN THE FORECAST...GENERALLY ACROSS THE SOUTHWEST PART OF THE AREA. WILL NEED TO KEEP AN EYE ON IT FOR POSSIBLE INCREASE IN POPS FOR SOME LIGHT SNOW...AGAIN GENERALLY ACROSS THE SOUTHWEST 1/3 OF THE AREA SUNDAY NIGHT. LITTLE TO TALK ABOUT MONDAY BUT MONDAY NIGHT FEATURES ANOTHER TROUGH AND INCREASING MOISTURE/CLOUDINESS MOVING TOWARD THE AREA FROM THE NORTHWEST. .LONG TERM (TUESDAY-FRIDAY)... GENERALLY FOLLOWED ECMWF GUIDANCE FOR THE EXTENDED AS IT HAS SHOWN THE BEST RUN TO RUN CONTINUITY AND ALSO RECEIVES SUPPORT FROM THE CANADIAN ENSEMBLE MEAN. APPEARS THE ACTIVE SYNOPTIC SCALE FLOW PATTERN WILL CONTINUE WITH A SERIES OF SHORTWAVE TROUGHS TRAVERSING THE CWA DURING THIS TIME FRAME. THE FIRST SYSTEM LOOKS TO ARRIVE ON CHRISTMAS DAY AS THE H5 RIDGE SLIDES OFF TO THE EAST. WHILE IT APPEARS MAIN AREA OF H85-H7 FRONTOGENESIS WILL STAY SOUTH OF OUR CWA...IT WILL BE CLOSE ENOUGH TO ALLOW AT LEAST SOME LIGHT SNOW TO FALL. WITH H85 WINDS AOB 20KTS...TRAVEL ISSUES DO NOT APPEAR TO BE A CONCERN AT THIS TIME. EC IS SLOWER IN MOVING THE SYSTEM OUT OF THE AREA SO HAVE SLIGHT CHC TO CHC POPS CONTINUING INTO WEDNESDAY. APPEARS WE WILL HAVE A VERY SHORT BREAK BEFORE THE NEXT SHORTWAVE TROUGH MOVES IN AROUND MIDDAY ON THURSDAY. DYNAMICS APPEAR A LITTLE BETTER FOR US WITH THIS STORM AS THE EC TRACKS THE H5 OPEN WAVE TROUGH OVER SOUTHWEST KANSAS. WENT WITH SLIGHT CHC POPS FOR NOW BUT WILL NEED TO MONITOR FUTURE RUNS FOR ANY NECESSARY ADJUSTMENTS. WILL SEE WEAK RIDGING START TO SET BY LATE FRIDAY AS THE SHORTWAVE TROUGH SHIFTS OFF TO THE NORTHEAST AND INTO THE WESTERN GREAT LAKES REGION. && .AVIATION... FOR THE 00Z TAF...NORTHWEST WINDS OF 25 TO 30 KTS WITH HIGHER GUSTS WILL BLOW THROUGH THE TAF PERIOD. SNOWFALL WILL BEGIN IN THE KGLD AREA SHORTLY BEFORE 06Z WHILE KMCK WILL NOT START TIL THE 06-09Z TIME FRAME. THE COMBINATION OF THE WIND AND SNOW WILL PRODUCE REDUCED VISIBILITIES IN SNOW AND BLOWING SNOW THROUGH ROUGHLY 12-15Z SATURDAY MORNING. FROM 15Z-22Z WINDS WILL REMAIN IN THE 20 TO 30 KT RANGE THEN QUICKLY FALL OFF WITH A GRADUAL CLEARING FROM WEST TO EAST. CIGS WILL BE IN THE MVFR/IFR RANGE THROUGH THE PRECIPITATION DURATION. && && .GLD WATCHES/WARNINGS/ADVISORIES... KS...SNOW AND BLOWING SNOW ADVISORY UNTIL 11 AM MST /12 PM CST/ SATURDAY FOR KSZ013>016-028-029-041-042. NE...NONE. CO...SNOW AND BLOWING SNOW ADVISORY UNTIL 11 AM MST SATURDAY FOR COZ091. && $$ BURTIS/DDT/BLM ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 200 PM MST FRI DEC 21 2007 .DISCUSSION...FORECAST CONCERNS ARE ON WINDS AND SNOW TONIGHT THROUGH EARLY IN THE DAY SATURDAY. MORE SNOW EXPECTED AGAIN CHRISTMAS DAY INTO WEDNESDAY WITH ANOTHER THURSDAY INTO FRIDAY. .SHORT TERM (TONIGHT-MONDAY NIGHT)... TONIGHT-SATURDAY...UPPER TROUGH AXIS CURRENTLY EXTENDING ALONG THE CONTINENTAL DIVIDE WILL MOVE ACROSS THE AREA OVERNIGHT AND BY 18Z BE EAST OF THE AREA. THE COMBINATION OF 850-500MB MOISTURE/MID LEVEL FRONTOGENESIS AND 250 JET DIVERGENCE WILL FAVOR HIGHEST POPS ACROSS SOUTHERN 2/3 OF THE AREA...HIGHEST ACROSS THE FAR SOUTH. TOTAL ACCUMULATIONS IN THIS AREA WILL RANGE FROM 1 TO 3 INCHES...HIGHEST SOUTH. LATEST NAM/RUC SHOWING SOME ORGANIZATION TO THE SNOW ACROSS INTERSTATE 70 WITH A LULL IN SNOW IN THE DOWNSLOPE AREAS OF CHEYENNE COUNTY COLORADO AND WALLACE KS. WILL ISSUE A SNOW AND BLOWING SNOW ADVISORY AS A RESULT FROM 03Z TONIGHT THROUGH 18Z SATURDAY. ELSEWHERE...WILL UPDATE THE HWO TO TALK ABOUT THE SNOW AND POTENTIAL FOR BLOWING SNOW OUTSIDE THE ADVISORY AREA. WILL KEEP SOME POPS MENTIONED ACROSS THE FAR EAST/SOUTHEAST THROUGH 18Z SATURDAY GIVEN TIMING DIFFERENCES AMONGST THE MODELS WITH REGARD TO HOW FAST THE SYSTEM LEAVES THE AREA. GFS/09Z SREF THE SLOWER OF THE MODELS WITH THE NAM/NGM A BIT QUICKER. AFTER 18Z IT SHOULD BE PRETTY MUCH OVER WITH...EXCEPT THE WIND. ONCE THE SNOW ENDS WE STILL HAVE TO DEAL WITH STRONG WINDS JUST OFF THE SURFACE AND INCREASING SUNSHINE AS THE SYSTEM MOVES EAST. QUESTION BECOMES WHETHER THE WIND WILL FULLY MIX TO THE SURFACE GIVEN EXISTING SNOW COVER AND EXPECTED LIGHT ACCUMULATIONS. FOR NOW WILL NOT ISSUE A WIND ADVISORY FOR THE 18Z- 22Z TIME FRAME GIVEN THE CONCERN LISTED ABOVE. SATURDAY NIGHT-SUNDAY...WILL HAVE A BRIEF PERIOD OF CLEAR SKIES BEFORE MID AND UPPER LEVEL MOISTURE SPREADS ACROSS THE AREA FROM THE NORTHWEST AFTER MIDNIGHT AS ANOTHER QUICK MOVING SYSTEM MAKES ITS WAY TOWARD THE AREA. COLUMN STARTS TO SATURATE IN THE 850-500 LAYER DURING THE DAY SUNDAY FROM NORTHWEST TO SOUTHEAST. DESPITE THE INCREASE IN MOISTURE DYNAMICS AND LIFT ARE LACKING...THUS WILL MAINTAIN A NO POP FORECAST. SUNDAY NIGHT-MONDAY NIGHT...WELL ORGANIZED UPPER DISTURBANCE EMBEDDED IN A DEEP AND COMPACT TROUGH WILL MOVE SOUTH THROUGH THE FRONT RANGE AND EASTERN PLAINS OF COLORADO INTO SOUTHWEST/SOUTH CENTRAL KANSAS BY THE END OF THE PERIOD. LOOKS LIKE THIS SYSTEM WILL SLIDE JUST FAR ENOUGH WEST AND SOUTH OF THE AREA TO KEEP SILENT POPS IN THE FORECAST...GENERALLY ACROSS THE SOUTHWEST PART OF THE AREA. WILL NEED TO KEEP AN EYE ON IT FOR POSSIBLE INCREASE IN POPS FOR SOME LIGHT SNOW...AGAIN GENERALLY ACROSS THE SOUTHWEST 1/3 OF THE AREA SUNDAY NIGHT. LITTLE TO TALK ABOUT MONDAY BUT MONDAY NIGHT FEATURES ANOTHER TROUGH AND INCREASING MOISTURE/CLOUDINESS MOVING TOWARD THE AREA FROM THE NORTHWEST. .LONG TERM (TUESDAY-FRIDAY)... GENERALLY FOLLOWED ECMWF GUIDANCE FOR THE EXTENDED AS IT HAS SHOWN THE BEST RUN TO RUN CONTINUITY AND ALSO RECEIVES SUPPORT FROM THE CANADIAN ENSEMBLE MEAN. APPEARS THE ACTIVE SYNOPTIC SCALE FLOW PATTERN WILL CONTINUE WITH A SERIES OF SHORTWAVE TROUGHS TRAVERSING THE CWA DURING THIS TIME FRAME. THE FIRST SYSTEM LOOKS TO ARRIVE ON CHRISTMAS DAY AS THE H5 RIDGE SLIDES OFF TO THE EAST. WHILE IT APPEARS MAIN AREA OF H85-H7 FRONTOGENESIS WILL STAY SOUTH OF OUR CWA...IT WILL BE CLOSE ENOUGH TO ALLOW AT LEAST SOME LIGHT SNOW TO FALL. WITH H85 WINDS AOB 20KTS...TRAVEL ISSUES DO NOT APPEAR TO BE A CONCERN AT THIS TIME. EC IS SLOWER IN MOVING THE SYSTEM OUT OF THE AREA SO HAVE SLIGHT CHC TO CHC POPS CONTINUING INTO WEDNESDAY. APPEARS WE WILL HAVE A VERY SHORT BREAK BEFORE THE NEXT SHORTWAVE TROUGH MOVES IN AROUND MIDDAY ON THURSDAY. DYNAMICS APPEAR A LITTLE BETTER FOR US WITH THIS STORM AS THE EC TRACKS THE H5 OPEN WAVE TROUGH OVER SOUTHWEST KANSAS. WENT WITH SLIGHT CHC POPS FOR NOW BUT WILL NEED TO MONITOR FUTURE RUNS FOR ANY NECESSARY ADJUSTMENTS. WILL SEE WEAK RIDGING START TO SET BY LATE FRIDAY AS THE SHORTWAVE TROUGH SHIFTS OFF TO THE NORTHEAST AND INTO THE WESTERN GREAT LAKES REGION. && .AVIATION... FOR THE 00Z TAF...NORTHWEST WINDS OF 25 TO 30 KTS WITH HIGHER GUSTS WILL BLOW THROUGH THE TAF PERIOD. SNOWFALL WILL BEGIN IN THE KGLD AREA SHORTLY BEFORE 06Z WHILE KMCK WILL NOT START TIL THE 06-09Z TIME FRAME. THE COMBINATION OF THE WIND AND SNOW WILL PRODUCE REDUCED VISIBILITIES IN SNOW AND BLOWING SNOW THROUGH ROUGHLY 12-15Z SATURDAY MORNING. FROM 15Z-22Z WINDS WILL REMAIN IN THE 20 TO 30 KT RANGE THEN QUICKLY FALL OFF WITH A GRADUAL CLEARING FROM WEST TO EAST. CIGS WILL BE IN THE MVFR/IFR RANGE THROUGH THE PRECIPITATION DURATION. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...SNOW AND BLOWING SNOW ADVISORY FROM 8 PM MST /9 PM CST/ THIS EVENING TO 11 AM MST /12 PM CST/ SATURDAY FOR KSZ013>016- 028-029-041-042. NE...NONE. CO...SNOW AND BLOWING SNOW ADVISORY FROM 8 PM THIS EVENING TO 11 AM MST SATURDAY FOR COZ091. && $$ DDT/FOLTZ/BURTIS ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 254 PM CST FRI DEC 21 2007 .DISCUSSION... DAYS 1-2... CONCERNS HAVE INCREASED THIS FORECAST PACKAGE REGARDING DANGEROUS SNOW AND BLOWING/DRIFTING SNOW THREAT...TO THE POINT THAT BLIZZARD WARNING IS NECESSARY ACROSS PORTIONS OF SOUTHWEST KANSAS. EARLY AFTERNOON WATER VAPOR LOOP WITH RUC ANALYSIS OVERLAY SHOWS CLUSTER OF MID LEVEL PV MAXIMA ACROSS FOUR CORNERS REGION. PRIMARY VORT MAX WAS JUST ENTERING WESTERN NEW MEXICO WITH PERSISTENT LIGHTNING STRIKES NOTED AS WELL. THE PRIMARY MID LEVEL VORT WILL CONTINUE TO ROUND THE BASE OF THE TROUGH AND EJECT NORTHEASTWARD DURING THE EVENING HOURS...SPAWNING SUBSTANTIAL LOWER TROPOSPHERIC DEVELOPMENT TO THE SOUTH OF DDC CWA ACROSS THE PANHANDLES. LATEST 12HR FORECAST OF RUC AND NAM SHOW FAIRLY STRONG CYCLOGENESIS IN THE H85-7 LAYER ALONG THE "GOLDEN PATH" FOR SOUTHWEST KANSAS HEAVY PRECIPITATION EVENT. AS A MATTER OF FACT...THE LATEST RUC AND NAM 18Z RUNS SUGGEST MORE LOWER TROPOSPHERIC DEVELOPMENT AND SUBSEQUENTLY STRONGER LIFT FOR HEAVIER PRECIPITATION. THE 18Z NAM SHOWS MORE QPF AS WELL AS A RESULT (ON THE ORDER OF 5 TO 8 INCHES OVER THE SOUTHWESTERN COUNTIES). THE GREATEST H7 FRONTOGENESIS ASSOCIATED WITH THE CYCLONE WILL BE FOCUSED MAINLY ALONG AND SOUTH OF THE ARKANSAS RIVER. IT STILL APPEARS THAT THE DURATION OF SNOWFALL AT ANY ONE LOCATION WILL BE AROUND 6 TO 8 HOURS ON AVERAGE. DURING THIS TIME FRAME...SUBSTANTIAL SURFACE WINDS WILL PREVAIL WITH SUSTAINED NORTH WINDS ON THE ORDER OF 25 TO 35 MPH. GUSTS ARE EXPECTED TO BE FREQUENTLY IN THE 35 TO 45 MPH RANGE...AND GIVEN THIS...HAVE DECIDED TO UPGRADE THE WINTER STORM WATCH TO A BLIZZARD WARNING FOR ROUGHLY SYRACUSE TO JETMORE TO KINSLEY...SOUTH TO THE OKLAHOMA BORDER. NORTH AND EAST OF THIS BLIZZARD WARNING WILL GO WITH A SNOW AND BLOWING SNOW ADVISORY. IN THE BLIZZARD WARNING AREA...AM EXPECTING WIDESPREAD 3 TO 5 INCHES WITH SOME LOCAL 6 OR 7 INCH AMOUNTS POSSIBLE...ALTHOUGH MEASURING THE SNOW WILL BE A DIFFICULT ENDEAVOR TO SAY THE LEAST. IN THE SNOW/BLOWING SNOW ADVISORY AREA...WILL GO WITH MAINLY 1 TO 3 INCHES WITH THE 3-HR WINDOW OF BELOW 1/4 MILE VISIBILITY LESS CERTAIN TO MEET BLIZZARD CRITERIA. TRAVEL IS EXPECTED TO BE NEARLY IMPOSSIBLE DURING THE OVERNIGHT HOURS AND EARLY SATURDAY MORNING ACROSS MUCH OF SOUTHWEST KANSAS...AND WILL EMPHASIZE THIS IN THE UPDATED WSW PRODUCT. IF THERE IS A SILVER LINING TO THIS STORM IT IS THE FACT THAT IT WILL BE AT ITS HEIGHT DURING THE OVERNIGHT AND EARLY MORNING HOURS SUCH THAT TRAVEL WILL LIKELY BE LIMITED AS IT IS -- THAT SAID...IF THE SYSTEM EVOLVES AND EJECTS JUST A FEW HOURS SLOWER...THIS WILL PUT THE BULK OF SATURDAY MORNING/THROUGH MIDDAY IN EXTREMELY HAZARDOUS CONDITIONS ACROSS MUCH OF THE AREA. THE WINDS WILL NOT DECREASE MUCH AT ALL THROUGH THE AFTERNOON...SO EVEN ONCE THE SNOW ENDS...LINGERING BLOWING AND DRIFTING WILL REMAIN A PROBLEM. THE LOW SHIFTS RAPIDLY EAST BY SAT AFTERNOON AND EVENING...WITH MUCH LIGHTER WESTERLY WINDS TAKING OVER. DOWNSLOPE FLOW SHOULD HELP ERODE COLD AIR FROM THE LOWER TROPOSPHERE...HOWEVER IF THERE IS SUBSTANTIAL NEW SNOW COVER...TEMPERATURES WILL BE DIFFICULT TO RECOVER SUNDAY (ABOVE THE LOWER 30S). -UMSCHEID DAYS 3-7... MAIN FORECAST CHALLENGES IN THIS EXTENDED PERIOD CONTINUE TO BE CHANCES OF SNOW WITH SEVERAL PROGRESSIVE SHORTWAVES INTO FRIDAY. AN UPPER SHORTWAVE TROUGH WILL BRING A CHANCE FOR SNOW ON MONDAY FOLLOWED BY A STRONGER WAVE ON TUESDAY NIGHT INTO WEDNESDAY, THEN ANOTHER ON THURSDAY INTO FRIDAY MORNING. IT IS MUCH TOO EARLY TO TELL HOW MUCH SNOW WITH ANY OF THESE SYSTEMS HOWEVER THE ONE ON MONDAY DOES NOT LOOK LIKE TOO MUCH ACCUMULATION. MODELS HAVE COME TO A GENERAL AGREEMENT ON THE POSITION OF THESE SHORTWAVES BUT THE EXACT STORM TRACK AND UPPER LIFT WITH EACH ARE STILL NOT IN THE REALM OF PREDICTION THEREFORE SNOW AMOUNTS WILL BE HARD TO GUESS. STILL SOME ACCUMULATIONS ARE PROBABLE WITH EACH SYSTEM ESPECIALLY THE LATTER ONES. AS FOR TEMPERATURES HIGHS SHOULD ONLY BE IN THE 30S WITH LOWS FROM THE UPPER TEENS TO LOW 20S. LOOKS LIKE A POSSIBLE WARMING TREND BY AROUND NEW YEARS. .AVIATION... VFR CONDITIONS WILL RAPIDLY DETERIORATE TO IFR BY AROUND 06Z TONIGHT AS SNOW AND BLOWING SNOW BEGINS WITH WINDS PICKING UP TO 25 TO 35KTS. THE SNOW COULD BECOME HEAVY ENOUGH BY 8Z TO 14Z WITH STRONG WIND GUSTS TO 45KTS WITH LIFR CONDITIONS. LOOK FOR RAPID IMPROVEMENT AROUND 18Z SATURDAY WITH WINDS GRADUALLY DECREASING WITH SNOW MOVING OFF TO THE EAST. VFR CONDITIONS SHOULD RETURN AFTER 20Z SATURDAY. && .PRELIMINARY POINT TEMPS/POPS... DDC 23 28 15 37 / 90 90 0 0 GCK 21 28 12 37 / 80 80 0 0 EHA 22 28 13 37 / 90 80 0 0 LBL 23 28 14 38 / 90 90 0 0 HYS 22 26 14 34 / 80 90 0 0 P28 27 30 16 36 / 80 90 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... SNOW AND BLOWING SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM CST SATURDAY FOR KSZ030-031-043>046-065-066-081-090. BLIZZARD WARNING FROM MIDNIGHT CST /11 PM MST/ TONIGHT TO 12 PM CST /11 AM MST/ SATURDAY FOR KSZ061>064-074>080-084>089. && $$ FN25/06/06 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 857 PM CST FRI DEC 21 2007 .UPDATE... AN AREA OF SEA FOG THAT DEVELOPED EARLIER TODAY ACROSS SOUTH- CENTRAL LOUISIANA HAS EXPANDED WESTWARD ALONG THE ENTIRE COAST OF SOUTHEAST TEXAS AND SOUTHWEST LOUISIANA...AS WELL AS SPREAD INLAND TO NEAR THE I-10 CORRIDOR. SABINE PASS AND NEW IBERIA HAVE REPORTED ZERO VISIBILITIES IN THE PAST HOUR...AND NUMEROUS REPORTS FROM MARINE PILOTS AND THE PUBLIC ON AND NEAR CALCASIEU AND SABINE LAKES HAVE INDICATED NEAR ZERO VISIBILITIES AS WELL. LOCATIONS CLOSER TO I-10 HAVE BEEN BOUNCING AROUND VISIBILITY-WISE BUT HAVE BEEN AS LOW AS 1 MILE. WENT AHEAD AND ISSUED A DENSE FOG ADVISORY FOR THE SOUTHERN ZONES AND NEARSHORE COASTAL WATERS. DIFFICULT TO DETERMINE WHEN FOG WILL BEGIN LIFTING...AS SURFACE WINDS WILL BEGIN INCREASING OVERNIGHT IN RESPONSE TO STORM SYSTEM MOVING OUT INTO THE PLAINS STATES. WILL LET MIDNIGHT CREW REEVALUATE THE SITUATION AND MAY CANCEL THE ADVISORY EARLIER THAN SCHEDULED. DESPITE LOW CLOUDS AND FOG...TEMPERATURES HAVE ALREADY FALLEN BELOW FORECASTED MINS FOR TONIGHT SO ADJUSTED LOWS DOWNWARD A TAD. HOWEVER...TEMPERATURES WILL EITHER REMAIN STEADY OR RISE OVERNIGHT AS WAA INCREASES AHEAD OF AFOREMENTIONED STORM SYSTEM. ALSO ADJUSTED SKY COVER UPWARD ALL AREAS DUE TO ONGOING CLOUD COVER. .MARINE... ISSUED SCEC FOR NEARSHORE WATERS AND SCA FOR OUTER WATERS AFTER MIDNIGHT AS GFS...NAM...AND RUC ALL INDICATE SURFACE WINDS WILL RISE ABOVE CRITERIA BETWEEN 6-9Z. DENSE FOG WILL BEGIN DISSIPATING AS SURFACE WINDS INCREASE OVERNIGHT...MOST LIKELY BETWEEN 9-12Z IF NOT SOONER...BUT UNCERTAINTY REMAINS. && .PREV DISCUSSION... /ISSUED 332 PM CST FRI DEC 21 2007/ SYNOPSIS...MOIST AIR IN THE LOWER LEVELS WILL ENCROACH FROM THE EAST AS HIGH PRESSURE MOVES BEYOND THE LOWER MISSISSIPPI VALLEY WITH FOG EAST OF THE ATCHAFALAYA RIVER AGAIN TONIGHT. RAIN CHANCES INCREASE ON SATURDAY AS THE NEXT PACIFIC COLD FRONT MOVES THROUGH. THE PATTERN REMAINS QUITE UNSETTLED NEXT WEEK WITH SEVERAL FRONTAL SYSTEMS MOVING THROUGH THE AREA ON CHRISTMAS EVE, WEDNESDAY, AND FRIDAY. SHORT TERM...MIN TEMPS LOOK TO BOTTOM OUT EARLY TONIGHT AS SOUTHEASTERLY FLOW OFF THE GULF BECOMES ESTABLISHED. LAID OFF OF BRINGING IN FOG DUE TO A LACK OF A GOOD FOG SIGNAL ON THE NGM MOS ALTHOUGH WOULD NOT BE SURPRISED IF DENSE FOG SETS UP AGAIN EAST OF THE ATCHAFALAYA. VISIBLE IMAGERY SHOWING FOG NEAR INTRACOASTAL CITY BUT IS RECEDING. KEPT POPS BELOW GUIDANCE ON SATURDAY AS MOST OF THE MOISTURE WILL BE MOVING OUT EARLY IN THE DAY PER LATEST NAM. LONG TERM...LONG WAVE PATTERN CONTINUES TO AMPLIFY SYSTEMS MOVING INTO TEXAS. THIS MAKES FOR A VERY UNSETTLED WEATHER PICTURE IN THIS HIGHLY PROGRESSIVE WAVE TRAIN. COULD SEE A FREEZE OVER MUCH OF THE AREA MONDAY MORNING AS A 1030HPA HIGH OUT OF CANADA SETTLES JUST NORTH OF THE AREA. AVIATION...IFR CIGS AND MVFR VIS AS A STRATUS DECK TRIES TO MOVE INTO THE LFT AND ARA AREAS THIS EVENING. BURNOFF WILL AGAIN BE LATE, CLOSER TO 18Z ON SATURDAY. MVFR CIGS AND VIS AFTER SUNRISE FOR LCH AS THAT STRATUS DECK/FOG BANK TRIES TO MOVE IN FROM THE EAST. VCTS AFTER 15Z IN ADVANCE OF A PACIFIC COLD FRONT. MARINE...CAUTION CRITERIA CAN BE REACHED AROUND MIDNIGHT TNITE AS SOUTHERLY WINDS INCREASE. SCA WILL LIKELY BE NEEDED AS THE COLD FRONT MOVES THROUGH SATURDAY EVENING. && .PRELIMINARY POINT TEMPS/POPS... KLCH 56 73 42 52 / 10 50 10 0 KBPT 57 72 41 47 / 10 40 10 0 KAEX 56 73 40 46 / 10 50 20 0 KLFT 57 73 42 53 / 10 50 30 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...DENSE FOG ADVISORY UNTIL 6 AM SATURDAY FOR THE FOLLOWING ZONES: ACADIA...CALCASIEU...CAMERON...IBERIA...JEFFERSON DAVIS... LAFAYETTE...LOWER ST. MARTIN...ST. MARY...UPPER ST. MARTIN...AND VERMILION. TX...DENSE FOG ADVISORY UNTIL 6 AM SATURDAY FOR THE FOLLOWING ZONES: JEFFERSON...AND ORANGE. GM...DENSE FOG ADVISORY UNTIL 6 AM SATURDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON, LA OUT 20 NM...AND COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA OUT 20 NM. SMALL CRAFT EXERCISE CAUTION FROM MIDNIGHT SATURDAY TO 9 AM SATURDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON, LA OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA OUT 20 NM... SMALL CRAFT ADVISORY FROM MIDNIGHT SATURDAY TO 9 AM SATURDAY FOR THE FOLLOWING ZONES: WATERS FROM CAMERON, LA TO HIGH ISLAND, TX EXTENDING FROM 20 NM TO 60 NM...WATERS FROM INTRACOASTAL CITY, LA TO CAMERON, LA EXTENDING FROM 20 NM TO 60 NM...AND WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA EXTENDING FROM 20 NM TO 60 NM. && $$ SHAMBURGER la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 955 AM CST FRI DEC 21 2007 .UPDATE...DENSE FOG BURN OUT DELAYED ON THE LONGEST NIGHT OF THE YEAR. SHOULD BE SEEING RAPID IMPROVEMENT OVER THE EASTERN ZONES VERY SHORTLY. WILL ISSUE UPDATED ZONES REMOVING PATCHY FOG ACCORDINGLY. OTHERWISE, LOWERED TEMPS TODAY DUE TO BOTH DELAYED BURNOFF AND WEAK SUN USING LATEST UPDATED RUC. && .PREV DISCUSSION... /ISSUED 610 AM CST FRI DEC 21 2007/ DISCUSSION...SHARP MOISTURE GRADIENT ACROSS EXTREME EASTER PARTS OF THE REGION...WHERE DEWPOINTS GO FROM 47 AT KLFT TO 59 AT KBTR. NOT COINCIDENTALLY...THIS ALSO SERVES AS THE DEMARCATION LINE FOR AREAS OF DENSE FOG...WHICH IS PRIMARILY OVER EASTERN PARTS OF LOUISIANA INTO MISSISSIPPI. WILL MENTION AREAS OF FOG WITH DENSE SPOTS OVER THE EXTREME EASTERN TIER OF PARISHES...BUT FOREGO AN ADVISORY WITH VISIBILITY BOUNCING AROUND A BIT...WORSENING A LITTLE JUST WEST OF THE ATCHAFALAYA WHILE IMPROVING EAST OF IT. SUNNY AND WARM CONDITIONS ON TAP FOR TODAY WITH HIGH PRESSURE AT THE SURFACE GRADUALLY SHIFTING EAST WHILE SHORTWAVE RIDGING ALOFT MOVES OVERHEAD. WILL START TO SEE MOISTURE RETURNING TO THE AREA LATE THIS AFTERNOON AND IN EARNEST LATE TONIGHT INTO EARLY SATURDAY ONCE THE SFC HIGH SHIFTS EAST OF THE AREA AND 30-40 LLJ DEVELOPS. THERE ARE DIFFERENCES AMONG THE NAM AND GFS THAT HAVE IMPORTANT IMPLICATIONS ON JUST HOW ACTIVE SATURDAY WILL OR WILL NOT BE. WITHOUT DELVING INTO THE GORY DETAILS...SUFFICE IT TO SAY IN SUMMARY THAT THE GFS OFFERS THE BETTER SEVERE POTENTIAL FROM A TIMING...KINEMATIC...AND THERMODYNAMIC PERSPECTIVE...THOUGH IN BOTH CASES INSTABILITY WILL BE A LIMITING FACTOR. TO THAT END...SPC HAS A "SEE TEXT" DENOTED FOR THE AREA...AND CONCUR WITH THAT ASSESSMENT GIVEN THE PRESENT UNCERTAINTY. WHAT DOES SEEM MORE CERTAIN IS STRONG SOUTHERLY WINDS AHEAD OF THE FRONT...FOLLOWED BY EVEN STRONGER NORTH WINDS BEHIND IT. A LAKE WIND ADVISORY IS POSSIBLE FOR PARTS OF THE AREA ON BOTH SIDES...PARTICULARLY ALONG THE COAST. SHOWERS AND THUNDERSTORMS EXPECTED TO COME TO AN END BY SATURDAY EVENING...WITH SUNDAY DOMINATED BY COLD AIR ADVECTION. FOR THE MEDIUM TO EXTENDED RANGE...HAVE CONTINUED TO LEAN ON THE ECMWF...WITH THE GFS COMING MORE IN LINE WITH ITS SOLUTIONS. IT WOULD SEEM THAT THIS SATURDAY FRONT WILL BE THE END OF THE 70 PLUS DEGREE DAYS FOR A WHILE...WITH THE TRAIN OF SHORTWAVES AMID THE PROGRESSIVE FLOW COMING FAST AND FURIOUS. LOOKS LIKE ABOVE NORMAL RAIN CHANCES ABOUT EVERY TWO DAYS OR SO...WITH THE FIRST SHOT AFTER THIS FRONT COMING MONDAY INTO...YEP...CHRISTMAS. THE HIGHEST POPS FALL ON CHRISTMAS EVE...WITH THINGS HOPEFULLY WINDING DOWN CHRISTMAS DAY AS THE UPPER TROF LIFTS OUT TOWARD THE MID ATLANTIC. ANOTHER WILL BE ON ITS HEELS...HOWEVER...AND WEDNESDAY LOOKS TO BE THE NEXT DECENT CHANCE. AVIATION...EASTERN TERMINALS...KARA...KLFT...AND KAEX...FLIRTING WITH EXPANSIVE AREA OF FOG PRIMARILY OVER SOUTHEAST AND NORTHEAST LOUISIANA THIS MORNING. THERE HAS BEEN SOME WESTWARD EXPANSION OVER THE PAST COUPLE OF HOURS...BUT ANY RESTRICTIONS WILL BE SHORT LIVED AND OCCUR GENERALLY PRIOR TO 13Z. MARINE...SOME PATCHY FOG THIS MORNING OVER THE 0-20NM ZONE FROM INTRACOASTAL CITY TO THE LOWER ATCHAFALAYA. OTHERWISE...LIGHT NORTH WINDS THIS MORNING WILL GRADUALLY BECOME EAST AND FINALLY SOUTH BY THIS AFTERNOON AS HIGH PRESSURE SHIFTS EAST OF THE AREA. SOUTHERLY FLOW WILL STRENGTHEN TONIGHT IN ADVANCE OF A COLD FRONT THAT IS FORECAST TO MOVE THROUGH THE COASTAL WATERS SATURDAY AFTERNOON INTO SATURDAY NIGHT. AN SCEC HEADLINE MAY BE WARRANTED TONIGHT AFTER MIDNIGHT AND SATURDAY PRIOR TO THE FRONT. SHOWERS AND THUNDERSTORMS WILL PRECEDE AND ACCOMPANY THE FRONT...WITH STRONG NORTHERLY WINDS AND BUILDING SEAS EXPECTED ONCE IT PASSES THROUGH. AN SCA SEEMS LIKELY FOR THESE CONDITIONS BEHIND THE FRONT. && .PRELIMINARY POINT TEMPS/POPS... KLCH 72 57 73 42 / 0 20 40 20 KBPT 73 58 72 41 / 0 20 30 10 KAEX 70 54 73 40 / 0 20 50 20 KLFT 72 58 76 43 / 0 20 40 30 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$ 11 la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 750 PM CST THU DEC 20 2007 .DISCUSSION... MUCH DRIER AIR HAS FILTERED IN BEHIND A COLD FRONT/DRY LINE WHICH ACCOMPANIED OUR UPPER LEVEL STORM SYSTEM EARLY THIS MORNING. THE BOUNDARY HAS JUST ABOUT PULLED UP STATIONARY ACROSS OUR EASTERN ZONES THIS EVENING AND IS NOT EXPECTED TO MAKE MUCH MORE EASTWARD PROGRESS OVERNIGHT. WITH THE CLEAR SKIES AND HIGH DEWPOINTS ACROSS THE EAST NOT TO MENTION THE WET GROUND CONDITIONS FROM RAINFALL THIS MORNING...ALREADY STARTING TO SEE VISIBILITIES CRATER AT ELD...MLU AND AEX. FOR THIS REASON...HAVE DECIDED TO POST A DENSE FOG ADVISORY THROUGH 900 AM FRIDAY MORNING RUNNING IT GENERALLY ALONG AND EAST OF A LINE FROM HOPE AND LEWISVILLE ARKANSAS TO MINDEN...COUSHATTA AND NATCHITOCHES LOUISIANA. IF THE LATEST RUC13 DATA IS TO BE BELIEVED...THEN WE COULD SEE THIS FOG ADVECT FURTHER WEST AFTER MIDNIGHT...ENCOMPASSING MUCH OF THE REGION PRIOR TO DAYBREAK FRIDAY. OTHER SHORT TERM PROGS KEEPING ENOUGH DRY AIR OUT WEST TO PRECLUDE FOG DEVELOPMENT BUT WILL HEDGE ON THE SIDE OF CAUTION AND JUST MENTION PATCHY FOG ACROSS NORTHEAST TEXAS AND PATCHY DENSE FOG ACROSS EXTREME NORTHWEST LOUISIANA INTO THE TEXARKANA AREA AND SOUTHEAST OKLAHOMA. WOULD NOT BE SURPRISED IF WE NEED TO EXPAND THE ADVISORY FURTHER WEST LATER TONIGHT BUT WILL CROSS THAT BRIDGE IF AND WHEN IT BECOMES NECESSARY. FCST MIN TEMPERATURES AND ALL OTHER GRIDS IN LINE SO NO OTHER CHANCES NECESSARY ATTM. UPDATE AND ADVISORY OUT SHORTLY...13. && .AVIATION... WATER VAPOR IMAGERY SHOWS TROUGH AXIS ON THE EASTERN SIDE OF THE MS VALLEY...W/00Z KSHV SOUNDING SHOWING A VERY DRY AMS IN PLACE. HOWEVER...W/WET SOILS...DECOUPLING...AND ABUNDANT RADIATIONAL COOLING...EXPECT DETERIORATING CEILINGS/VSBYS TO IFR/LIFR...W/KELD ALREADY IN THE SOUP AT 02Z. LATEST RUC INDICATES SW AR AND LA MOST FAVORED FOR FOG. EXPECT CONDITIONS TO QUICKLY IMPROVE TO VFR AFTER SUNRISE. FORECAST SOUNDINGS INDICATE CONVECTIVE TEMPS FRIDAY AFTERNOON IN THE TRIPLE DIGITS...SO NO CU FIELD EXPECTED. && .PRELIMINARY POINT TEMPS/POPS... SHV 46 73 53 68 / 0 0 20 50 MLU 48 73 53 69 / 0 0 20 60 DEQ 40 69 49 61 / 0 0 10 40 TXK 47 71 53 63 / 0 0 10 50 ELD 46 73 51 70 / 0 0 10 60 TYR 42 75 54 64 / 0 0 20 30 GGG 41 74 52 67 / 0 0 20 40 LFK 41 76 52 72 / 0 0 30 50 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...DENSE FOG ADVISORY UNTIL 9 AM FRIDAY FOR THE FOLLOWING ZONES: COLUMBIA...HEMPSTEAD...LAFAYETTE...NEVADA...AND UNION AR. LA...DENSE FOG ADVISORY UNTIL 9 AM FRIDAY FOR THE FOLLOWING ZONES: BIENVILLE...CALDWELL...CLAIBORNE...GRANT...JACKSON...LA SALLE...LINCOLN...NATCHITOCHES...OUACHITA...RED RIVER...UNION LA...WEBSTER...AND WINN. OK...NONE. TX...NONE. && $$ 13/44 la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 145 PM EST FRI DEC 21 2007 .AVIATION...A LARGE AREA OF HIGH PRESSURE CURRENTLY LOCATED OVER QUEBEC...WILL KEEP SOUTHEAST FLOW OVR THE GREAT LAKES REGION THIS AFTERNOON INTO SATURDAY. THE SOUTHEAST FLOW OVR LAKE HURON WILL KEEP AT LEAST A BKN LAKE INDUCED LOW CLOUD DECK...OVER THE APN TAF SITE INTO TONIGHT. THE REST OF NRN LWR WILL SEE MVFR/VFR CONDS INTO THIS EVENING. LATER TONIGHT WARMER AIR WILL BEGIN TO MOVE INTO THE GREAT LAKES REGION...FROM A STORM SYSTEM MOVING INTO THE WRN LAKES. THE WARMER AIR MOVING OVER THE SNOW PACK ACROSS NRN MICHIGAN...WILL GENERATE LOW CLOUDS/FOG AND DRIZZLE. THIS WILL GENERATE IFR CIG AND VSBY CONDS OVERNIGHT ACROSS THE NRN MI TAF SITES. LIFR CIGS AND VSBYS ARE EXPECTED OVER NRN MICHIGAN SATURDAY BTW 12Z AND 18Z...AS WARM AIR CONTS TO PUSH NORTH INTO THE REGION... GENERATING LOW CLOUDS/DRIZZLE/RAIN AND FOG. SWR && .UPDATE...ISSUED 1117 AM FRI DEC 21 LITTLE TO NONE OF THE RETURNS ON THE RADAR ARE MAKING IT TO THE GROUND. SO HAVE SLASHED THE POPS FOR THE REST OF THE DAYTIME AS MID LEVEL DRY AIR CONTINUES OVER THE REGION. SO FAR, THE NAM AND RUC HAVE THE BETTER HANDLE ON THE 850 MB MOISTURE MOVING IN WHICH LOOKS THE BEST. SO HAVE SCT SPRINKLES IN THE FORECAST FOR THE AFTERNOON. BASED ON THE LOWER CLOUDS (AROUND 1500 FEET) AT ANJ, AS WELL AS BELOW FREEZING TEMPERATURES, PUT PATCHY ZL- IN FOR E UPPER WITH IT CHANGING TO SCT SPRINKLES FOR THE AFTERNOON AS THE TEMEPERATURES WARM AND THE DRY AIR PUSHES THE LOWER CLOUDS OUT. OTHERWISE, TEMPERATURES AND WINDS LOOK GOOD. LUTZ && .PREV DISCUSSION... /ISSUED 738 AM EST FRI DEC 21 2007/ AVIATION...BKN MVFR CIGS ANTICIPATED ACROSS PORTIONS OF NRN LOWER MICHIGAN THIS MORNING...PARTICULARLY AT PLN/APN WITH SE FLOW OFF LAKE HURON PUSHING LOW CLOUD COVER INTO THOSE AREAS. OTHERWISE... SPOTTY ELEVATED SHOWER ACTIVITY WILL BE FOUND ACROSS THE REGION TODAY ALONG ADVANCING NOSE OF WARM AIR AND MOISTURE ALOFT. LOWERING CIGS/VSBYS ALONG WITH AREAS OF DRIZZLE ANTICIPATED TONIGHT LEADING TO MVFR AND EVENTUALLY IFV CONDITIONS AT ALL THREE TAF LOCATIONS. ADAM && DISCUSSION...ISSUED AT 509 AM. LONGWAVE TROUGH PATTERN PREVALENT ACROSS NORTH AMERICA WITH A MYRIAD OF AMPLIFYING SHORTWAVES MOVING THROUGH THE FLOW. MOST SIGNIFICANT OF THESE WAVES...AND WHAT WILL BE THE MAIN FOCUS IN THE FORECAST FOR THE WEEKEND...BEGINNING TO TRAVERSE THE EXPANSE OF THE ROCKIES. ONE PIECE OF ENERGY NOW DIGGING INTO THE SW STATES WHILE ANOTHER WAVE IN WESTERN CANADA. OPERATIONAL NAM/GFS SOLUTIONS AS WELL AS THE GFS ENSEMBLES AND ECMWF SOLUTION ALL STILL DEPICTING A TROUGH MERGER BETWEEN THESE TWO SYSTEMS OVER THE UPPER MIDWEST... LATE SATURDAY THROUGH SUNDAY...AND ASSOCIATED RAPID SPIN-UP OF A DEEP SFC LOW OVER NRN MICHIGAN. IN THE MEANTIME...STILL PLENTY TO THINK ABOUT IN THE SHORT TERM. BUILDING MID LEVEL RIDGING DOWNSTREAM OF THIS SYSTEM AND INCREASING LOW LEVEL WARM/MOISTURE ADVECTION INTO THE WESTERN GREAT LAKES EXPECTED TO DOMINATE TODAY THROUGH MUCH OF SATURDAY...WITH CHANCES FOR LIGHT SHOWER AND DRIZZLE/FREEZING DRIZZLE ACTIVITY THE MAIN FORECAST ISSUES. TODAY AND TONIGHT...MID CLOUD COVER AND ELEVATED RADAR RETURNS ALONG ADVANCING MID LEVEL MOISTURE GRADIENT CONTINUE TO PRESS INTO THE REGION FROM THE WEST-SOUTHWEST. HOWEVER...MORE WIDESPREAD LOW CLOUD COVER AND DRIZZLE ACTIVITY STILL WAY BACK ACROSS CENTRAL WISCONSIN INTO WESTERN UPPER MICHIGAN...ALTHOUGH SOME STRATUS HAS DEVELOPED/ EXPANDED ACROSS THE HIGHER TERRAIN OF NE LOWER MICHIGAN OVERNIGHT. THUS FAR...RADAR RETURNS LOOK CONVECTIVE IN NATURE AS AXIS OF STEEPER MID LEVEL LAPSE RATES PRESSES OUT OF WISCONSIN. BUT OUTSIDE OF A COUPLE OBS IN SW LOWER MICHIGAN SHOWING PRECIP OVERNIGHT... NOTHING REALLY GETTING TO THE GROUND THUS FAR. HOWEVER...RADAR RETURNS HAVE INCREASED IN COVERAGE OVER THE LAST HOUR OR SO AND PROBABLY NEED TO CARRY SOME SORT OF PRECIP THIS MORNING AS THE MOISTURE AXIS AND STEEPER LAPSE RATES LIFT UP THROUGH THE REGION. QUESTION IS...WHAT WILL IT BE? FORECAST NAM SOUNDINGS FOR THIS MORNING DEPICT ABOVE FREEZING LAYER ALOFT NOSING INTO THE REGION. BUT GIVEN THE DRY LOW LEVEL AIR STILL IN PLACE AND CONVECTIVE NATURE TO THE PRECIP...THINK ANYTHING THAT DOES REACH THE GROUND WILL BE OF THE FROZEN VARIETY. TIME WILL TELL OF COURSE BUT FOR NOW WILL CARRY CHANCY SNOW SHOWER WORDING THROUGH MIDDAY. THEN BY LATER THIS AFTERNOON THROUGH SATURDAY...LOW LEVEL MOISTURE FINALLY GETS SHOVED INTO THE REGION LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING...SETTING THE STAGE FOR AREAS OF FOG AND DRIZZLE TO DEVELOP. HAVE NOT CHANGED MUCH TO THE GOING FORECAST IN THIS REGARD OTHER THAN SLOWING DOWN THE DEVELOPMENT OF WIDESPREAD FOG AND DRIZZLE UNTIL LATER IN THE EVENING...AND ADDING FREEZING DRIZZLE TO SOME OF THE HIGHER TERRAIN AREAS WHERE TEMPS WILL LIKELY HOVER AROUND FREEZING. SOUPY CONDITIONS THEN EXPECTED TO PERSIST THROUGH SATURDAY ALTHOUGH CONTINUING WARM ADVECTION/MOISTENING ALOFT MAY BRING BETTER CHANCES FOR MEASURABLE PRECIP INTO THE REGION. IN ANY EVENT...A DREARY...DAMP COOL DAY LOOKS ON TAP FOR NRN MICHIGAN WITH TEMPS SLOWLY REACHING THE 35 TO 40 DEGREE MARK. SATURDAY NIGHT THROUGH SUNDAY...TROUGH MERGER SLATED TO TAKE SHAPE OVER THE UPPER MIDWEST BRINGING ABOUT A RAPID SPIN UP OF A DEEP SFC LOW NEARLY OVER THE STATE...TRACKING UP ACROSS EASTERN LAKE SUPERIOR ON SUNDAY. VERY STRONG DYNAMICS COME INTO PLAY IN THIS SCENARIO AND AT THIS POINT CATEGORICAL POPS ARE JUSTIFIED SATURDAY NIGHT INTO SUNDAY WITH A GOOD SWATH OF PRECIP RUNNING UP THROUGH THE REGION. ALSO AT THIS POINT...MAINLY RAIN ANTICIPATED SATURDAY NIGHT WITH THE LOW DEEPENING JUST WEST OF THE REGION AND +4C OR BETTER H8 AIR GETTING SHOVED UP THROUGH EASTERN UPPER MICHIGAN. A RAPID CHANGEOVER TO SNOW AS WELL AS SOUTHWEST-WEST LAKE EFFECT/ENHANCED SNOW SHOWERS EXPECTED TO FOLLOW SUNDAY AS CORE OF -14C OR COLDER H8 AIR ROTATES AROUND INTO LOWER MICHIGAN. A LOT OF WIND AND THE POTENTIAL FOR HEAVY SNOW/NEAR BLIZZARD CONDITIONS WITH THIS SYSTEM SUNDAY AND SUNDAY NIGHT WILL LIKELY WARRANT HEADLINES IN THE NEXT 1 TO 2 FORECAST CYCLES. TBA CHRISTMAS EVE AND CHRISTMAS...LAKE AGGREGATE TROUGHING WILL CONTINUE ACROSS THE GREAT LAKES THROUGH THE DAY ON MONDAY...BEFORE 850MB TEMPERATURES WARM TO AROUND -5C BY 00Z MONDAY. WITH SURFACE TROUGH ROTATING ACROSS NORTHERN MICHIGAN EARLY MONDAY MORNING...EXPECT TO SEE FAIRLY WIDESPREAD SNOW SHOWERS AND BLOWING SNOW. DURING THE DAY ON MONDAY...DEEPER MOISTURE STARTS TO PULL OUT AND PRECIPITATION SLOWLY BECOMES PURELY LAKE EFFECT. FINALLY...AS THE BOUNDARY LAYER WARMS...LAKE EFFECT WILL END MONDAY EVENING. HIGH PRESSURE WILL BECOME ESTABLISHED OVER THE GREAT LAKES BY CHRISTMAS DAY...PROVIDING A FAIRLY PLEASANT DAY WITH HIGHS WARMING INTO THE LOWER 30S UNDER PARTLY SUNNY SKIES AFTER STARTING THE DAY IN THE TEENS. KAS && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR LMZ341. LH...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR LHZ346. LS...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR LSZ321. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1117 AM EST FRI DEC 21 2007 .UPDATE...LITTLE TO NONE OF THE RETURNS ON THE RADAR ARE MAKING IT TO THE GROUND. SO HAVE SLASHED THE POPS FOR THE REST OF THE DAYTIME AS MID LEVEL DRY AIR CONTINUES OVER THE REGION. SO FAR, THE NAM AND RUC HAVE THE BETTER HANDLE ON THE 850 MB MOISTURE MOVING IN WHICH LOOKS THE BEST. SO HAVE SCT SPRINKLES IN THE FORECAST FOR THE AFTERNOON. BASED ON THE LOWER CLOUDS (AROUND 1500 FEET) AT ANJ, AS WELL AS BELOW FREEZING TEMPERATURES, PUT PATCHY ZL- IN FOR E UPPER WITH IT CHANGING TO SCT SPRINKLES FOR THE AFTERNOON AS THE TEMEPERATURES WARM AND THE DRY AIR PUSHES THE LOWER CLOUDS OUT. OTHERWISE, TEMPERATURES AND WINDS LOOK GOOD. LUTZ && .PREV DISCUSSION... /ISSUED 738 AM EST FRI DEC 21 2007/ AVIATION...BKN MVFR CIGS ANTICIPATED ACROSS PORTIONS OF NRN LOWER MICHIGAN THIS MORNING...PARTICULARLY AT PLN/APN WITH SE FLOW OFF LAKE HURON PUSHING LOW CLOUD COVER INTO THOSE AREAS. OTHERWISE... SPOTTY ELEVATED SHOWER ACTIVITY WILL BE FOUND ACROSS THE REGION TODAY ALONG ADVANCING NOSE OF WARM AIR AND MOISTURE ALOFT. LOWERING CIGS/VSBYS ALONG WITH AREAS OF DRIZZLE ANTICIPATED TONIGHT LEADING TO MVFR AND EVENTUALLY IFV CONDITIONS AT ALL THREE TAF LOCATIONS. ADAM DISCUSSION...ISSUED AT 509 AM. LONGWAVE TROUGH PATTERN PREVALENT ACROSS NORTH AMERICA WITH A MYRIAD OF AMPLIFYING SHORTWAVES MOVING THROUGH THE FLOW. MOST SIGNIFICANT OF THESE WAVES...AND WHAT WILL BE THE MAIN FOCUS IN THE FORECAST FOR THE WEEKEND...BEGINNING TO TRAVERSE THE EXPANSE OF THE ROCKIES. ONE PIECE OF ENERGY NOW DIGGING INTO THE SW STATES WHILE ANOTHER WAVE IN WESTERN CANADA. OPERATIONAL NAM/GFS SOLUTIONS AS WELL AS THE GFS ENSEMBLES AND ECMWF SOLUTION ALL STILL DEPICTING A TROUGH MERGER BETWEEN THESE TWO SYSTEMS OVER THE UPPER MIDWEST... LATE SATURDAY THROUGH SUNDAY...AND ASSOCIATED RAPID SPIN-UP OF A DEEP SFC LOW OVER NRN MICHIGAN. IN THE MEANTIME...STILL PLENTY TO THINK ABOUT IN THE SHORT TERM. BUILDING MID LEVEL RIDGING DOWNSTREAM OF THIS SYSTEM AND INCREASING LOW LEVEL WARM/MOISTURE ADVECTION INTO THE WESTERN GREAT LAKES EXPECTED TO DOMINATE TODAY THROUGH MUCH OF SATURDAY...WITH CHANCES FOR LIGHT SHOWER AND DRIZZLE/FREEZING DRIZZLE ACTIVITY THE MAIN FORECAST ISSUES. TODAY AND TONIGHT...MID CLOUD COVER AND ELEVATED RADAR RETURNS ALONG ADVANCING MID LEVEL MOISTURE GRADIENT CONTINUE TO PRESS INTO THE REGION FROM THE WEST-SOUTHWEST. HOWEVER...MORE WIDESPREAD LOW CLOUD COVER AND DRIZZLE ACTIVITY STILL WAY BACK ACROSS CENTRAL WISCONSIN INTO WESTERN UPPER MICHIGAN...ALTHOUGH SOME STRATUS HAS DEVELOPED/ EXPANDED ACROSS THE HIGHER TERRAIN OF NE LOWER MICHIGAN OVERNIGHT. THUS FAR...RADAR RETURNS LOOK CONVECTIVE IN NATURE AS AXIS OF STEEPER MID LEVEL LAPSE RATES PRESSES OUT OF WISCONSIN. BUT OUTSIDE OF A COUPLE OBS IN SW LOWER MICHIGAN SHOWING PRECIP OVERNIGHT... NOTHING REALLY GETTING TO THE GROUND THUS FAR. HOWEVER...RADAR RETURNS HAVE INCREASED IN COVERAGE OVER THE LAST HOUR OR SO AND PROBABLY NEED TO CARRY SOME SORT OF PRECIP THIS MORNING AS THE MOISTURE AXIS AND STEEPER LAPSE RATES LIFT UP THROUGH THE REGION. QUESTION IS...WHAT WILL IT BE? FORECAST NAM SOUNDINGS FOR THIS MORNING DEPICT ABOVE FREEZING LAYER ALOFT NOSING INTO THE REGION. BUT GIVEN THE DRY LOW LEVEL AIR STILL IN PLACE AND CONVECTIVE NATURE TO THE PRECIP...THINK ANYTHING THAT DOES REACH THE GROUND WILL BE OF THE FROZEN VARIETY. TIME WILL TELL OF COURSE BUT FOR NOW WILL CARRY CHANCY SNOW SHOWER WORDING THROUGH MIDDAY. THEN BY LATER THIS AFTERNOON THROUGH SATURDAY...LOW LEVEL MOISTURE FINALLY GETS SHOVED INTO THE REGION LATER THIS AFTERNOON AND ESPECIALLY THIS EVENING...SETTING THE STAGE FOR AREAS OF FOG AND DRIZZLE TO DEVELOP. HAVE NOT CHANGED MUCH TO THE GOING FORECAST IN THIS REGARD OTHER THAN SLOWING DOWN THE DEVELOPMENT OF WIDESPREAD FOG AND DRIZZLE UNTIL LATER IN THE EVENING...AND ADDING FREEZING DRIZZLE TO SOME OF THE HIGHER TERRAIN AREAS WHERE TEMPS WILL LIKELY HOVER AROUND FREEZING. SOUPY CONDITIONS THEN EXPECTED TO PERSIST THROUGH SATURDAY ALTHOUGH CONTINUING WARM ADVECTION/MOISTENING ALOFT MAY BRING BETTER CHANCES FOR MEASURABLE PRECIP INTO THE REGION. IN ANY EVENT...A DREARY...DAMP COOL DAY LOOKS ON TAP FOR NRN MICHIGAN WITH TEMPS SLOWLY REACHING THE 35 TO 40 DEGREE MARK. SATURDAY NIGHT THROUGH SUNDAY...TROUGH MERGER SLATED TO TAKE SHAPE OVER THE UPPER MIDWEST BRINGING ABOUT A RAPID SPIN UP OF A DEEP SFC LOW NEARLY OVER THE STATE...TRACKING UP ACROSS EASTERN LAKE SUPERIOR ON SUNDAY. VERY STRONG DYNAMICS COME INTO PLAY IN THIS SCENARIO AND AT THIS POINT CATEGORICAL POPS ARE JUSTIFIED SATURDAY NIGHT INTO SUNDAY WITH A GOOD SWATH OF PRECIP RUNNING UP THROUGH THE REGION. ALSO AT THIS POINT...MAINLY RAIN ANTICIPATED SATURDAY NIGHT WITH THE LOW DEEPENING JUST WEST OF THE REGION AND +4C OR BETTER H8 AIR GETTING SHOVED UP THROUGH EASTERN UPPER MICHIGAN. A RAPID CHANGEOVER TO SNOW AS WELL AS SOUTHWEST-WEST LAKE EFFECT/ENHANCED SNOW SHOWERS EXPECTED TO FOLLOW SUNDAY AS CORE OF -14C OR COLDER H8 AIR ROTATES AROUND INTO LOWER MICHIGAN. A LOT OF WIND AND THE POTENTIAL FOR HEAVY SNOW/NEAR BLIZZARD CONDITIONS WITH THIS SYSTEM SUNDAY AND SUNDAY NIGHT WILL LIKELY WARRANT HEADLINES IN THE NEXT 1 TO 2 FORECAST CYCLES. TBA CHRISTMAS EVE AND CHRISTMAS...LAKE AGGREGATE TROUGHING WILL CONTINUE ACROSS THE GREAT LAKES THROUGH THE DAY ON MONDAY...BEFORE 850MB TEMPERATURES WARM TO AROUND -5C BY 00Z MONDAY. WITH SURFACE TROUGH ROTATING ACROSS NORTHERN MICHIGAN EARLY MONDAY MORNING...EXPECT TO SEE FAIRLY WIDESPREAD SNOW SHOWERS AND BLOWING SNOW. DURING THE DAY ON MONDAY...DEEPER MOISTURE STARTS TO PULL OUT AND PRECIPITATION SLOWLY BECOMES PURELY LAKE EFFECT. FINALLY...AS THE BOUNDARY LAYER WARMS...LAKE EFFECT WILL END MONDAY EVENING. HIGH PRESSURE WILL BECOME ESTABLISHED OVER THE GREAT LAKES BY CHRISTMAS DAY...PROVIDING A FAIRLY PLEASANT DAY WITH HIGHS WARMING INTO THE LOWER 30S UNDER PARTLY SUNNY SKIES AFTER STARTING THE DAY IN THE TEENS. KAS AVIATION... /ISSUED 1154 PM EST THU DEC 20 2007/ MID/HIGH CLOUDS ACROSS NORTHERN MI OVERNIGHT...SOME ST OVER LAKE HURON MAY IMPACT APN THIS EVENING. CLOUD COVER AND PERSISTENT SOUTHEAST FLOW MAY IMPACT FOG POTENTIAL AT TERMINAL SITES OVERNIGHT. CEILINGS WILL LOWER DURING THE DAY FRIDAY...PREVAILING MVFR CONDITIONS EXPECTED. SOME DRIZZLE OR LIGHT RAIN POSSIBLE DURING THE AFTERNOON. JPB && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR LMZ341. LH...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR LHZ346. LS...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR LSZ321. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1235 AM EST WED DEC 19 2007 UPDATED AVIATION DISCUSSION .SHORT TERM (TONIGHT THROUGH THU)... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR PRECIPITATION SATURDAY THROUGH SUNDAY. WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW AND ASSOCIATED TROUGH MOVING OVER EASTERN ONTARIO AND A RIDGE SHIFT INTO THE WESTERN ONTARIO AND MINNESOTA. ANOTHER TROUGH IS DEVELOPING OVER MIDDLE HIGH PLAINS. SURFACE ANALYSIS DEPICTS A LOW OVER THE LOWER GREAT LAKES WITH A BROAD HIGH OVER THE OHIO RIVER VALLEY. A RIDGE RUNS FROM THE HIGH NORTH THROUGH WISCONSIN AND THE WEST PART OF THE FORECAST AREA. A STATIONARY FRONT STRETCHES FROM NEW ENGLAND THROUGH THE LOW TO THE ARROWHEAD OF MINNESOTA. A WARM FRONT RUNS FROM IOWA NORTHWEST TO SOUTHEAST SASKATCHEWAN THEN WEST TO CENTRAL BRITISH COLUMBIA. A LARGE HIGH BLANKETS THE ROCKIES. THE MID LEVEL RIDGE WILL SLIDE OVER THE FORECAST AREA OVERNIGHT WHICH WILL CAUSE THE WINDS TO DROP OFF AND BACK SOUTH. THE TROUGH THAT IS DEVELOPING OVER THE HIGH PLAINS WILL SWEEP ACROSS THE CENTRAL PLAINS INTO THE MIDDLE MISSISSIPPI RIVER VALLEY ON THURSDAY. THE WISCONSIN RIDGE WILL SHIFT OVER THE FORECAST AREA BY THIS EVENING AND INTO EASTERN ONTARIO ON THURSDAY. 850MB TEMPERATURES OF AROUND -7C OVER EASTERN LAKE SUPERIOR AND NORTHWEST WINDS WILL SUPPORT SOME LAKE EFFECT SNOW ENHANCEMENT OVER THE PART OF THE EASTERN U.P. TONIGHT. THERE SHOULD BE SOME LIMITED CLEARING TONIGHT AND RADIATIONAL COOLING WILL BRING THE TEMPERATURES DOWN TO THE DEW POINT. SOUTHERLY WINDS WILL ALSO HELP PUSH THE TEMPERATURES UP TO AROUND FREEZING ON THURSDAY. SOUNDING DATA SHOWING DRY AIR AND AN INVERSION SETTLING DOWN TO 950MB OVER THE FORECAST WHICH TOGETHER COULD PRODUCE SOME PATCHY FOG TONIGHT THIS WILL BURN OFF ON THURSDAY WITH SURFACE WARMING. WEAK SHORTWAVE MOVING THROUGH WESTERN LAKE SUPERIOR ON THURSDAY COULD PRODUCE SOME LIGHT SNOW MAINLY OVER THE WESTERN. .LONG TERM (THU NIGHT THROUGH NEXT WED)... MAIN FORECAST CONCERN REMAINS ON POTENTIAL FOR HEAVY SNOW SAT NIGHT INTO SUN. THU NIGHT THROUGH SAT...SOUTHERLY WINDS WILL PREVAIL UNTIL A LOW PRESSURE TROUGH SWINGS ACROSS UPPER MI ON SAT (12Z ECMWF IS SLOWER THAN 12Z GFS). INCREASED HIGH TEMPS ON FRIDAY TO ACCOUNT FOR WAA OUT OF THE SSE. MAY NEED TO INCREASE HIGHS MORE IN FUTURE FORECASTS. AS FAR AS PCPN TYPE GOES...MAINLY KEPT WITH GOING FORECAST. IT LOOKS LIKE UPSLOPE AREAS WITH A SSE WIND (WESTERN AND CENTRAL U.P.) WILL SEE BETTER CHANCE OF FREEZING DRIZZLE...AND OTHER AREAS MAY SEE DRIZZLE. FCST SOUNDINGS IN BUFKIT FOR IRON MOUNTAIN ON FRIDAY SHOW GREATER VALUES OF OMEGA AT LOW LEVELS THAN IN MQT AND HOUGHTON. THE TEMPS IN IRON MOUNTAIN REMAIN NEARLY ISOTHERMALLY AROUND 0C UP THROUGH 850MB. THE MAIN SATURATED LAYER ALSO OCCURS AT TEMPS GREATER THAN -10C...SO DRIZZLE IS ALMOST CERTAIN. FOR MQT AND HOUGHTON...POSITIVE OMEGA VALUES UP TO +5...MID-LEVEL DRY AIR...AND SFC TEMPS AROUND 0C LEAD TO UNCERTAINTY IN THE CHANCES OF FREEZING DRIZZLE VS. SNOW VS. NO PCPN AT ALL FOR FRI. CHANCES FOR PCPN INCREASE ACROSS ALL OF THE U.P. BY SAT MORNING AS THE LOW PRESSURE SYSTEM APPROACHES THE REGION. SAT NIGHT THROUGH WED...MODELS HAVE BECOME IN MUCH BETTER AGREEMENT WITH THE END OF THE WEEKEND SYSTEM...AND AT LEAST UP IN THE GREAT LAKES AREA...ARE IN PRETTY GOOD AGREEMENT THROUGH WED. AT 00Z SUN...06Z MODELS PROG THE UPPER LOW OVER SASKATCHEWAN ON FRI TO DROP DOWN INTO NORTHERN MN ON SAT...WHILE A SHRTWV TROUGH MOVES FROM NEW MEXICO UP INTO SW MISSOURI. THERE STILL REMAINS ISSUES WHETHER OR NOT THE SHRTWV AND UPPER LOW WILL PHASE TOGETHER...AS NOTED BY THE 06Z GFS KEEPING THEM UNPHASED. WILL CONTINUE TO SIDE WITH THE PHASED IDEA OF THE ECMWF/CANADIAN...WHICH PHASE THEM TOGETHER NEAR LAKE HURON ON SUNDAY. THIS RESULTS IN A 1007MB LOW OVER ILLINOIS SAT EVENING TO LIFT N AND DEEPEN RAPIDLY...REACHING NORTHERN LAKE HURON AT 12Z SUN WITH A PRESSURE AROUND 990MB. THE LOW WILL THEN TRACK UP INTO NE ONTARIO LATER SUN AND INTO QUEBEC ON MONDAY. FOR UPPER MI...THE TRACK IS FAVORABLE FOR HEAVY SYNOPTIC SNOW...WITH Q-VECTOR CONVERGENCE PROGS SUGGESTING FROM THE NORTHERN U.P. UP TO JAMES BAY. LOOKS LIKE TOO THAT AT LEAST AFTER 00Z SUN...MUCH OF THE PCPN WILL SWITCH OVER TO SNOW AS COLD AIR MOVES IN. THERE ARE TWO OTHER ASPECTS OF THIS EVENT TOO. AS THE UPPER LOW APPROACHES SAT NIGHT...850MB TEMPS PLUMMET COMPARED TO 12Z SAT...WITH READINGS DROPPING TO -8C EAST TO -15C WEST BY 12Z SUN. THUS LAKE ENHANCEMENT LOOKS LIKE A PRETTY GOOD BET. GIVEN THE LOW TRACK...SURFACE AND 850MB WIND FIELDS SUGGEST RIGHT NOW THAT THE BEST ENHANCEMENT IS OVER NORTHWEST SNOW-BELTS. THE OTHER ASPECT TO THIS SYSTEM IS WIND...WITH THE 00Z ECMWF SHOWING 850MB WINDS INCREASING TO 45-50 KT BY 00Z MON. THUS SOME BLOWING AND DRIFTING SNOW IS LIKELY... BEGINNING SAT NIGHT. SYNOPTIC SNOW SHOULD CHANGE OVER TO A PURE LAKE EFFECT REGIME LATER SUN NIGHT AS THE UPPER AND SURFACE LOWS PULL AWAY...WHILE 850MB TEMPS SLOWLY WARM TO AROUND -10C BY 12Z MON. WILL DRY OUT CHRISTMAS EVE A BIT MORE NOW...SINCE MOST MODELS PROG UPPER AND SURFACE RIDGING TO MOVE INTO THE CWA. ONLY LAKE EFFECT CHANCES WILL REMAIN IN NW SNOWBELTS. SHOULD THE SCENARIO OF THE UPPER LOW AND SHRTWV NOT PHASE TOGETHER AS SHOWN BY THE 06Z GFS...THE EVENT WILL TURN OUT WITH MORE PURE LAKE EFFECT SNOW FOR WEST AND NW SNOWBELTS...ALONG WITH BLOWING SNOW. THUS...GIVEN THE DIFFERENCES BETWEEN THE ECMWF AND GFS...ANYONE TRAVELING THIS WEEKEND SHOULD CONTINUE TO MONITOR LATER FORECASTS. FOR CHRISTMAS EVE NIGHT INTO CHRISTMAS DAY...THE WEATHER LOOKS PRETTY TRANQUIL...WITH ONLY A WEAK SHRTWV TROUGH CROSSING CHRISTMAS EVE NIGHT. THE ECMWF AND GFS DEPICT LITTLE IF ANY PCPN FROM THIS...AND THUS WILL NOT INCLUDE ANY IN THE FORECAST. ALSO...WITH SW FLOW DURING THIS PERIOD AND 850MB TEMPS CLIMBING TO -4 TO -6C BY 00Z WED...NO NEED FOR ANY LAKE EFFECT PCPN CHANCES. A NORTHERN STREAM SHRTWV TROUGH IS SHOWN BY THE GFS AND ECMWF TO APPROACH THE CWA TUE NIGHT AND WED. WILL BRING IN SOME SNOW CHANCES ON TUE NIGHT OVER WESTERN LAKE SUPERIOR...THEN ACROSS THE CWA ON WEDNESDAY AS THE TROUGH MOVES THROUGH AND 850MB TEMPS DROP TO GENERATE LAKE EFFECT SNOW. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... LOOK FOR MVFR CIGS AT BOTH LOCATIONS TO LOWER TO IFR AS FLOW BECOMES SE (UPSLOPE AT BOTH LOCATIONS) AND DRYING/SUBSIDENCE ALOFT KEEPS MOISTURE TRAPPED AT LOW-LEVELS. MOIST UPSLOPE FLOW MAY ALSO CONTRIBUTE TO TEMPORARY IFR VBSYS LATE TONIGHT AT KSAW. EXPECT SOME IMPROVEMENT AT KCMX BY LATE THU MORNING WHERE FLOW WILL SHIFT SSE WHICH IS NOT AS FAVORED AN UPSLOPE DIRECTION. SSE FLOW SHOULD CONTINUE TO KEEP KSAW SOCKED IN UNDER MVFR CIGS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THE PRESSURE GRADIENT UNDER A RIDGE THAT EXTENDS FROM FROM QUEBEC INTO NORTHERN LAKE SUPERIOR WAS PRODUCING LIGHT NE TO N WINDS. AS THE RIDGE MOVES OFF TO THE EAST ON THURSDAY...SOUTHERLY FLOW WILL INCREASE ON LAKE SUPERIOR WITH WINDS TO NEAR 30 KT BY THURSDAY NIGHT INTO EARLY FRIDAY. A STRONG SURFACE LOW IS EXPECTED TO MOVE TOWARDS THE UPPER GREAT LAKES ON SATURDAY. DEPENDING ON THE TRACK AND TIMING...GALE FORCE WINDS COULD DEVELOP FROM LATE SATURDAY INTO SUNDAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...DLG LONG TERM...AJ/MRC AVIATION...VOSS MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1152 PM EST WED DEC 19 2007 .AVIATION...LOW LEVEL MOISTURE REMAINING TRAPPED BELOW INVERSION LEADING TO WIDESPREAD MVFR STRATUS DECK ACROSS THE TAF SITES THIS MORNING...ESPECIALLY OVER KAPN AND KPLN. MIST FORMATION A LITTLE SLOW GETTING GOING THIS EVENING AND HAVE BACKED OFF THIS POSSIBILITY SOMEWHAT...ONLY SHOWING A SLIGHT DROP IN VISIBILITIES. HAVE GONE A LITTLE MORE OPTIMISTIC TOMORROW...HAVING SKIES SCATTER OUT DURING THE MORNING/EARLY AFTERNOON...LEADING TO VFR CONDITIONS. WINDS WILL REMAIN LIGHT AND VARIABLE TONIGHT...BECOMING LIGHT SOUTHEAST THURSDAY. MSB && .UPDATE...ISSUED 955 PM PER 11U-3.9U SATELLITE IMAGERY...EXPANSIVE SUB 2KFT STRATUS DECK OVER THE NORTHERN LAKES REGION THIS EVENING AS REMNANT LOW LEVEL MOISTURE (WITH SOME ADDITIONAL NORTHWEST FLOW MOISTURE FLUX FROM THE BIG LAKES) REMAINS TRAPPED BELOW STRENGTHENING SUBSIDENCE INVERSION. JUST ENOUGH OVER WATER INSTABILITY TO PRODUCE SCATTERED FLURRIES OVER FAVORED NORTHWEST FLOW AREAS OF NORTHERN LOWER MICHIGAN. HOWEVER...EXPECT THIS TO DIMINISH DURING THE NEXT SEVERAL HOURS AS WAA OVERSPREADS THE LAKES. EXPECT CLOUD SHIELD TO PRETTY MUCH REMAIN STATUS QUO OVER MUCH OF THE AREA...WITH THE EXCEPTION OF FAR SOUTH PARTS OF THE AREA WHERE MODEL PROGS SHOW JUST ENOUGH DRYING TO POTENTIALLY SCOUR OUT SOME OF THE CLOUD DECK. NOCTURNAL TEMPERATURE RESPONSE RATHER SLOW ONCE AGAIN THIS EVENING...WITH TEMPERATURES SEVERAL DEGREES WARMER THAN INITIALLY PROGGED. GIVEN THIS SLOWER THAN ANTICIPATED DROP...WILL GO AHEAD AND BUMP TEMPERATURES UP A COUPLE DEGREES ACROSS THE BOARD. OTHERWISE...STILL EXPECTING PATCHY/AREAS OF FOG DEVELOPMENT WITH FURTHER BOUNDARY LAYER COOLING. RECENT BELLAIRE OBSERVATION THAT TEMPORARY DROPPED TO A QUARTER MILE IN FOG ADDS CONFIDENCE TO THIS SCENARIO. BESIDES AFOREMENTIONED TEMPERATURE ADJUSTMENT...REST OF FORECAST IN GREAT SHAPE WITH LITTLE CHANGES WARRANTED. UPDATED GRIDS/NEARSHORES/ZONES OUT SHORTLY. MSB && .DISCUSSION...ISSUED 400 PM LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW SHORTWAVE TROUGHING ACROSS THE GREAT LAKES WITH AN ASSOCIATED SURFACE LOW MOVING ACROSS SE ONTARIO. WEAK SURFACE TROUGH EMANATING FROM THIS LOW IS EXTENDING ACROSS THE STRAITS REGION...BUT APPEARS TO BE LOOSING ITS INFLUENCE OVERALL ACROSS NORTHERN MICHIGAN. CONVERGENCE ALONG THIS TROUGH AND GENERAL CYCLONIC FLOW HAS HELPED MAINTAIN IFR TO MVFR CLOUD DECK ACROSS THE AREA...BUT SHALLOW AND MARGINAL OVER-LAKE INSTABILITY HAS NOT BEEN ENOUGH TO GENERATE LAKE EFFECT SNOW SHOWERS WITHIN NW FLOW REGIMES. RADAR RETURNS ARE REALLY SPOTTY AND LIGHT AT THIS HOUR WITH PERHAPS ONLY FLURRIES OR EVEN LIGHT DRIZZLE PRESENT AS SFC TEMPS HAVE WARMED ABOVE FREEZING THIS AFTERNOON. SURFACE RIDGE AXIS UPSTREAM OVER WISCONSIN WILL HAVE ITS SIGHTS SET ON NORTHERN MICHIGAN OVERNIGHT...BUT STILL PLENTY OF LOW CLOUDS AND FOG RESIDE FROM NORTHERN MICHIGAN ON WEST TO THE RIDGE AXIS. LOW LEVEL CLOUDS CLEAR OUT TO THE WEST OF THE RIDGE AXIS...BUT MID-LEVEL WARM ADVECTION CLOUDS ALREADY PUSHING EAST INTO THE UPPER MIDWEST. CLOUDS AND TEMPS ARE THE MAIN FORECAST CONCERNS TONIGHT. TONIGHT...SURFACE LOW WILL CONTINUE TO PUSH OFF TO THE EAST INTO THE NEW ENGLAND STATES WHILE THE LOW LEVEL RIDGE AXIS BUILDS IN ACROSS NORTHERN MICHIGAN OVERNIGHT. PRIOR TO THE ARRIVAL OF THE RIDGE AXIS...LIGHT NORTHWEST WINDS COMBINED WITH SHALLOW OVER-WATER INSTABILITY (LAKE-900MB TEMP DIFFERENCE AROUND -10C) WILL SPELL SCT LAKE EFFECT FLURRIES IN THE SNOWBELTS DURING THE EVENING. OTHERWISE...INCREASING SHORTWAVE RIDGING ALOFT WILL PROMOTE DRYING IN THE MID-LEVELS AND DECREASING INVERSION HEIGHTS. LOW LEVEL MOISTURE REALLY DOES NOT HAVE ANYWHERE TO GO OVERNIGHT SINCE THE MOISTURE IS TRAPPED BENEATH THE INVERSION AND LOW LEVEL ADVECTIONS WILL BE RATHER LIGHT. NAM12 925-850MB RH DETAILS SOME DRYING TAKING PLACE IN THE WESTERN ZONES...BUT THAT MAY BE A FUNCTION OF LOWERING INVERSION HEIGHTS AND NOT INDICATIVE OF THE ACTUAL AMOUNT OF LOW CLOUDS THAT ARE PRESENT. PLENTY OF LOW CLOUDS UPSTREAM NEAR THE SURFACE RIDGE AXIS ACROSS WISCONSIN...IN ADDITION TO ONSHORE AND UPSLOPE FLOW WITH THE NW WINDS AND A LINGERING LOW LEVEL CONVERGENCE AXIS THAT SETS UP ACROSS NORTHEAST LOWER AND EASTERN UPPER...AND EVAPORATIVE COOLING AT THE TOP OF THE LOW LEVEL MOIST LAYER SUPPORTS GOING MOSTLY CLOUDY TO CLOUDY THE ENTIRE NIGHT...WITH LOWERING OF THE LOW LEVEL CLOUD BASE. WITH COOLING OF THE BL AND ADDED MOISTURE TO THE BL FROM ABOVE FREEZING SURFACE TEMPS THE PAST TWO AFTERNOONS...PATCHY FOG SHOULD DEVELOP POSSIBLY BECOMING MORE WIDESPREAD ACROSS THE HIGHER TERRAIN DEPENDING UPON HOW MUCH CLOUD BASES LOWER. LOWS WILL RANGE FROM THE UPPER TEENS NEAR CAD AND HTL TO THE MID 20S ALONG THE GREAT LAKES SHORELINES. MPC THURSDAY...WEAK CONVERGENCE AXIS ACROSS NRN LAKE HURON WILL WANE AS SFC RIDGE AXIS SLIDES EAST OF THE REGION IN THE MORNING. TRAPPED LOW CLOUDS ASSOCIATED WITH THIS TROUGH MAY BREAK APART FOR A BRIEF TIME IN THE MORNING...BUT AS WINDS TURN AROUND TO THE SOUTH WITH CONTINUING SHALLOW OVERLAKE INSTABILITY...CLOUDS SHOULD FILL BACK IN ACROSS EASTERN UPPER. ELSEWHERE...SHALLOW/SUB 1500KFT MOISTURE WITH ADDED SFC MOISTURE FROM SNOWMELT...WILL KEEP AREAS OF FOG AND LOW CLOUD AROUND FOR A GOOD DEAL OF THE MORNING. WONDERING HOW MUCH OF THE LOW CLOUD AND FOG WILL ACTUALLY GET TRAPPED IN FOR MUCH OF THE DAY. THIS ONE IS A TOUGH CALL. THERE WILL BE 925 MB WARM ADVECTION THAT INCREASES THROUGH THE DAY...AND WILL LIKELY BRING SOME PARTLY CLOUDY SKIES TO THE SW CWA BY AFTERNOON. OVERALL...BELIEVE THAT A MOSTLY CLOUDY FORECAST WITH LINGERING AREAS OF FOG INTO THE EARLY AFTERNOON IS THE BEST CALL...ESPECIALLY WITH MID TO UPPER LEVEL CLOUDS ADVANCING ITO THE CWA IN THE AFTERNOON. HIGHS AGAIN IN THE LOW TO MIDDLE 30S. THURSDAY NIGHT...WITH THE CONTINUED MILD TEMPERATURES...MORE SNOWMELT WILL CONTINUE TO CREATE QUITE THE SOUPY BL. WOULD NOT BE SURPRISED TO SEE AT LIGHT FOG NEVER REALLY ERODING FROM THURSDAY AFTERNOON...AND JUST CONTINUE INTO THURSDAY NIGHT. DIFFICULT TO DISCERN HOW MUCH MID/UPPER CLOUD WILL BE AROUND. MID LEVEL WEAK WARM ADVECTION/ISENTROPIC UPGLIDE (290-295K) PERSISTS THROUGH THE NIGHT...BUT WEAK MID LEVEL SHORTWAVE DEPARTS EAST BY 12Z WITH SOME MID LEVEL RIDGING. THIS COULD ALLOW FOR SOME DRIER AIR ALOFT TO ARRIVE LATE...HELPING TO PROMOTE THICKENING FOG. EITHER WAY...FOG IN SOME FASHION WILL BE AROUND...AND WHETHER OR NOT AREAS OF/PATCHY IS USED CAN BE SAVED FOR TOMORROW`S FORECAST PACKAGE. AM NOT EXPECTING MUCH OF A TEMP FALL UNDER THE CLOUDS/WARM ADVECTION...LOWS GENERALLY IN THE MIDDLE 20S CAN BE EXPECTED. FRIDAY AND FRIDAY NIGHT...HEIGHTS CONTINUE TO RISE IN THE MID LEVELS AS SRN/NRN JET STREAM ENERGY RIPS INTO THE ROCKIES. THE SOUTHERLY FLOW ACROSS THE GREAT LAKES INCREASES RESULTING IN BETTER/STRONGER WARM AND MOIST AIR ADVECTION. WINDS OF DEEPER H8-H5 MOISTURE SWINGS THROUGH THE CWA FRIDAY. FORECAST SOUNDINGS NO INDICATIVE OF ANY MEASURABLE PRECIPITATION...BUT RATHER LOW LEVEL MOISTURE THICKENING TO NEAR 750MB...ALL WARMER THAN -10C. THIS IS LOOKING MORE AND MORE LIKE A DRIZZLE SCENARIO...HINTED AT YESTERDAY. WILL BRING AREAS OF DRIZZLE INTO THE REGION STARTING FRIDAY AFTERNOON...THEN PROGRESSING THROUGH ALL OF THE CWA FRIDAY NIGHT. OF COURSE...FOG WILL ACCOMPANY THE DRIZZLE. AS FAR AS TEMPS...MID TO UPPER 30S FOR HIGHS ON FRIDAY WITH NEAR STEADY TEMPERATURES THROUGH THE NIGHT. FEEL AS IF ALL AREAS WILL BE ABOVE 32F...SO NO NEED ATTM TO MENTION FREEZING DRIZZLE. SATURDAY...THERE ARE SOME COMMONALITIES IN THE MODELS IN THIS TIME PERIOD. NRN AND SRN STREAM ENERGY WORK THEIR WAY NEAR THE MISSISSIPPI VALLEY...REMAINING SEPARATE SYSTEMS WITH NO APPARENT PHASING (YET?). THE MORNING...IF TIMING IS CORRECT...WILL START OFF DRIZZLY AND FOGGY...BEFORE SFC LOW PRESSURE WORKS INTO THE WESTERN GREAT LAKES...ALONG WITH FORCING FROM SHORTWAVES. WILL KEEP THIS PERIOD SORT OF GENERAL. WILL GO WITH LIKELY RAIN FOR NRN LOWER AS AIR MASS LOOKS TO STAY WARM. LEFT A MIX IN FOR EASTERN UPPER...AND IN LINE WITH NEIGHBORING OFFICES. THESE DETAILS WILL BECOME CLEARER TOMORROW. SATURDAY NIGHT ONWARD...BOY...STILL LOOKING LIKE A COMMON SOLUTION BETWEEN THE MODELS IS JUST A LITTLE TOO FAR AWAY. OVERALL CONSENSUS IS TO STAY WITH THE ECMWF...AS THE GFS KEEPS THE TWO JET BRANCHES SEPARATE. THE 18Z NAM HAS NOW ALLOWED FOR THE TWO BRANCHES TO PHASE TOGETHER...SUCH AS THE 12Z ECMWF. THIS SCENARIO WOULD PULL THE EXPECTED STRONG STORM SYSTEM FURTHER BACK TO THE NW...WHILE RAPIDLY DEEPENING THE SFC LOW. AREAS OF RAIN WOULD PERSIST ACROSS THE NE CWA INTO THE EVENING WHILE STRONG COLD ADVECTION BLOWS IN FROM THE SW. THERE ARE JUST TOO MANY UNCERTAINTIES STILL. FOR AT LEAST ONE MORE TIME...WILL GO WITH RAIN AND SNOW IN THE EVENING...MOST AREAS...THEN CHANGE TO ALL SNOW OVERNIGHT WITH WINDS BECOMING QUITE BRISK SUNDAY/SUNDAY NIGHT). EXPECT CHANGES TO THIS FORECAST AS MORE DETAILED TIMING/STRENGTH AND EVOLUTION OF THIS STORM WILL COME IN DUE TIME. DID INCREASE CHANCES FOR PRECIPITATION TO LIKELY. THAT LOOKS LIKE THE SAFEST BET. THE POTENTIAL FOR HAZARDOUS TRAVEL IS CERTAINLY STILL THERE OVER THE WEEKEND PRIOR TO THE CHRISTMAS HOLIDAY...SO STAY TUNED FOR THE DETAILS TO ARRIVE IN LATER FORECASTS. A RATHER BRIEF PERIOD OF LAKE EFFECT SNOWS ARE EXPECTED ON THE BACKSIDE OF THIS STORM SYSTEM AS IT PULLS EAST SUNDAY NIGHT INTO MONDAY. QUITE A BIT OF DRY AIR IS ACTUALLY FORECAST TO SPREAD IN BY MONDAY NIGHT. SMD && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 615 AM CST FRI DEC 21 2007 .DISCUSSION... LOTS OF WX CONCERNS FOR THE NXT 48 HRS. PRIMARY ISSUE FOR TDA...AT LEAST FOR THIS MRNG...IS DENSE FOG THAT CURRENTLY BLANKETS ENTR FCST AREA. WITH ONLY A MODEST INCR IN MIXING DURG THE DAY...AND WITH SFC/LO LVL TRAJECTORIES CONTINUING TO PUSH HIER DWPT AIR INTO REGION...THINK IMPROVEMENT WILL BE FAIRLY SLOW. PREVIOUSLY ISSUED DENSE FOG ADVISORY RUNS UNTIL 16Z AND HAVE OPTED TO NOT EXTEND IT ATTM AS CLIMO FAVORS SM INCR IN VSBYS...ALBEIT MODEST...IN THE 15-16Z TIME FRAME. IF ST HOLDS ENTR DAY AS SUGGESTED BY INVERSION ON FCST SNDGS...TEMPS ARE GOING TO STRUGGLE TO WRM. BASED ON YSTDAS DIURNAL RECOVERY HV GIVEN MOST AREAS A MAX TEMP ABT 10 DEGREES ABV GOING READINGS. ATTENTION THEN TURNS TO SYSTEM MOVING THROUGH AREA SAT AND SAT NGT. SPEED AND INTENSITY OF SYS CONTS TO VARY A BIT FROM MODEL TO MODEL AND FROM RUN TO RUN. HWVR...IT APRS THAT GFS IS TOO SLOW WITH THE SYSTEM...AND MODEL CONSENSUS OF WRF/NAM...ECMWF...SREF...AND CANADIAN ALL SEEMS TO SUGGEST LEANING TWD A MORE PROGRESSIVE SOLN. FCST FROM 18Z SAT-12Z SUN GENLY FOLLOWS A SREF/WRF-NAM BLEND FOR MOST ELEMENTS. ALTHO INITIALLY ON SAT MRNG MSTR WILL BE LIMITED...INCRG S FLOW AHD OF TROF SHUD RAPIDLY MOISTEN THE AMS AOB 500 MB...AND PCPN SHUD BGN TO BLOSSOM AS UVV ASSOC WITH TROF WORKS INTO MSVLY. COLDER AIR WILL THEN WORK EWD...CHGG RAIN TO SNOW OVR W COUNTIES DURG THE AFTN...AND OVR THE IL COUNTIES ON SAT EVE. ALL MODELS KEEP SYSTEM OPEN...WITH NO WELL-DEFINED SFC OR 850 MB LOW TRACK ON WHICH TO BASE SNOW POTENTIAL. USING CONSENSUS QPF AND MODEL SNDGS TO TIME CHGOVER TO SNOW SUGGESTS BEST CHC FOR ACCUM SNOW WILL BE OVR N/W COUNTIES...RUFLY FROM N OF COU TO NR UIN. SINCE SYSTEM IS MOVING SO FAST DON`T THINK SNOWFALL ACCUMULATIONS WILL BE EXTREMELY HIGH...BUT AM WORRIED ABT THE EFFECT OF VRY STG WNDS IN WAKE OF SYSTEM COMBINING WITH ANY SNOW THAT DOES ACCUMULATE. TO HIGHLIGHT THE THREAT HV CONTD MENTION OF BLOWING AND DRIFTING SNOW IN AREAS THAT APPEAR TO HV A CHC OF OVER AN INCH OF ACCUMULATION...AND WL ALSO EMPHASIZE THIS CONCERN IN HWO. ALL PCPN WITH SYSTEM SHUD END BY 12Z SUN...ALTHO GUSTY WINDS SHUD CONT THRUOUT THE DAY...SPCLY IN N SECTIONS OF THE FA. TRUETT && .AVIATION... FOR THE 12Z TAFS...SHOULD ONLY SEE A SLOW IMPROVEMENT IN VSBYS AND A SLOW RISE IN CEILING HGTS BGNG AT 15Z TO 16Z WITH SLOWLY INCRSG SELY SFC WNDS. WITH FCTS SOUNDINGS SHOWING BNDRY LYR MOISTURE TRAPPED BLW AN INVERSION THRU THE DAY THE STRATUS CEILING SHOULD CONT. THE LATEST RUC FCST DOES SHOW LWRG RH IN THE 925 MB LYR BY 21Z FRI OVR COU. WILL FCST BKN020 IN COU AT 21Z...BUT WILL KEEP AN OVERCAST CEILING AT 700 FT IN UIN...STL AND SUS THRU THE AFTN HRS. WILL IMPROVE THE VSBYS TO 2SM BR BY 16Z...AND THEN TO 4SM BR AT 18Z FRI AT THE TAF SITES. VSBYS SHOULD CONT TO IMPROVE THIS EVNG WITH THE STRATUS LYR CONTG TO SLOWLY RISE WITH MDLS DEPICTING INCRSG LOW LVL S-SELY WNDS...ALTHOUGH THE BNDRY LYR REMAINS VERY MOIST. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR AUDRAIN- BOONE-CALLAWAY-COLE-CRAWFORD-FRANKLIN-GASCONADE-IRON- JEFFERSON-KNOX-LEWIS-LINCOLN-MADISON-MARION-MONITEAU-MONROE- MONTGOMERY-OSAGE-PIKE-RALLS-REYNOLDS-SHELBY-ST. CHARLES-ST. FRANCOIS-ST. LOUIS-ST. LOUIS CITY-STE. GENEVIEVE-WARREN- WASHINGTON. IL...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR ADAMS IL- BOND IL-BROWN IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL- JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL- MONTGOMERY IL-PIKE IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON IL. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1142 PM CST THU DEC 20 2007 .DISCUSSION... /1042 PM CST THU DEC 20 2007/ WILL GO AHEAD AND ISSUE A DENSE FOG ADVISORY FOR REST OF FORECAST AREA EXCEPT FOR THE KANSAS COUNTIES AND CASS AND BATES COUNTIES IN MISSOURI. WILL START THE ADDITIONAL COUNTIES AS OF MIDNIGHT. CURRENT FOG CONTINUES TO SPREAD WESTWARD AT AROUND 5 KTS. DEEPER MOISTURE CAN BE SEEN ON SATELLITE SPREADING INTO NORTHWEST MISSOURI...WHILE FOG IS SHALLOWER BUT STILL STILL PRODUCING LOW VSBYS IN SOUTHWEST MISSOURI. THINK THE SLIGHT INCREASE IN THE LOW LEVEL WINDS LATER TONIGHT WILL HAVE THE MOST IMPACT ON THIS SHALLOWER MOISTURE SO WILL LEAVE SOUTHWEST COUNTIES OUT OF THE ADVISORY AT THIS POINT. PC && .PREV DISCUSSION... /850 PM CST THU DEC 20 2007/ DENSE FOG CONTINUES TO SPREAD TO THE WEST UNDER INFLUENCE OF A VERY WEAK SURFACE FLOW AROUND LOW PRESSURE TROUGH IN EASTERN MISSOURI AT THIS TIME. MODELS SHOW THIS TROUGH BREAKING DOWN AS STRONGER TROUGHING IN HIGH PLAINS STARTS TO TAKE SHAPE OVERNIGHT WITH LOW LEVEL FLOW BECOMING SOUTHEAST. THIS SHOULD SLOW THE WESTWARD PROGRESSION AFTER MIDNIGHT BUT MAY SPREAD IT MORE INTO NORTHWEST MISSOURI...WHICH IS ALREADY EXPERIENCING PATCHY DENSE FOG UNDER THE CLEAR SKIES AND LIGHT WINDS. BOTH NAM AND RUC 950 MB DEPICTIONS OF THIS MOISTURE WOULD SUGGEST IT MAKING TO NEAR THE MISSOURI KANSAS BORDER IN NORTHWEST MISSOURI OVERNIGHT AND INTO EASTERN PORTIONS OF THE KANSAS CITY METRO AREA. FOR NOW...WILL GO AHEAD AND EXPAND THE ADVISORY TO INCLUDE AREAS THAT ARE SEEING THE WIDESPREAD DENSE FOG SPREADING IN AT THIS TIME...AND KEEP AN EYE ON THE TRENDS...ADDING COUNTIES AS NEEDED. PC /720 PM CST THU DEC 20 2007/ HAVE MADE SEVERAL PHONE CALLS TO AREAS JUST WEST OF WHERE WE HAD FOG ADVISORY IN EFFECT...AND THEY ARE VERIFYING THE SATELLITE TREND OF THE LOWER VISIBILITIES SPREADING BACK TO THE WEST. WILL EXPAND THE DENSE FOG ADVISORY FURTHER TO THE WEST TO COVER. ESPECIALLY CONCERNED FOR THE INTERSTATES INCLUDING I70 FROM CONCORDIA EASTWARD AND I35 IN HARRISON COUNTY. PC /414 PM CST THU DEC 20 2007/ FORECAST CONCERNS FOR THE FIRST HALF OF THE FORECAST ARE TWO FOLD. TONIGHT WE ARE LOOKING AT CONTINUED DENSE FOG ACROSS AREAS FROM NORTH CENTRAL AND NORTH EAST MISSOURI SOUTH THROUGH CENTRAL MISSOURI. THE SECOND FORECAST CONCERN IS THE WINTER STORM EXPECTED THIS WEEKEND. MOISTURE TRAPPED IN THE BOUNDARY LAYER...AND LIGHT WINDS ASSOCIATED WITH A SURFACE TROUGH...HAVE CONSPIRED TODAY TO KEEP THE EASTERN THIRD OF THE FORECAST AREA UNDER DENSE FOG. CONDITIONS ARE NOT EXPECTED TO CHANGE ACROSS THAT AREA OVERNIGHT. SURFACE TROUGH WILL SLIDE EAST A LITTLE...BUT ONLY ENOUGH TO ALLOW SURFACE WINDS TO SWITCH TO THE SOUTHEAST...ADVECTING MORE MOISTURE IN AT THE SURFACE. HAVE GONE WITH A DENSE FOG ADVISORY FOR THE REST OF THE AFTERNOON THROUGH 10 AM FRIDAY MORNING AS A RESULT. FARTHER WEST SKIES CLEARED TODAY AND THE FOG THAT SET IN DISSIPATED RATHER QUICKLY. TONIGHT WILL SEE THE INVERSION TRAP ABUNDANT MOISTURE AT THE SURFACE AGAIN...BUT WINDS JUST ABOVE THE INVERSION WILL STAY A LITTLE HIGHER IN RESPONSE TO THE DEEPENING TROUGH IN THE WESTERN CONUS. EXPECT THIS SLIGHTLY HIGHER WIND ABOVE THE INVERSION TO INDUCE ENOUGH MIXING OVERNIGHT TO PREVENT THE FOG FROM BECOMING AS DENSE ACROSS THE WESTERN TWO THIRDS OF THE FORECAST AREA. IN FACT...HAVE KEPT FOG OUT OF THE FORECAST FOR AREAS FROM THE KANSAS CITY METRO ON SOUTH AS MODEL SOUNDINGS SHOW THE SURFACE MOISTURE TO BE PARTICULARLY SHALLOW. THIS WILL NEED TO BE WATCHED OVERNIGHT THOUGH IN CASE RADIATION FOG BEGIN TO DEVELOP UNDER THE CLEAR SKIES. ATTENTION THEN TURNS TOWARDS FRIDAY NIGHT AND SATURDAY AS THE DEEPENING WEST CONUS TROUGH SWEEPS EAST THROUGH THE PLAINS. GFS AND ECMWF HAVE CONTINUED TO CONVERGE TOWARDS ONE SOLUTION FOR THIS WEEKENDS SYSTEM...AND THE NAM-WRF SEEMS TO BE MOVING IN THE SAME DIRECTION. THE EARLY WEEKEND SHORTWAVE TROUGH WILL ACTUALLY CONSIST OF A NORTHERN AND SOUTHERN STREAM WAVES PHASING AS THEY THEY MOVE THROUGH MISSOURI. THERE IS A STRONG SHOT OF COLD AIR THAT WILL QUICKLY SPREAD ACROSS THE FORECAST AREA SATURDAY. THIS SYSTEM WILL BE BRINGING THE BULK OF ITS MOISTURE FROM THE PACIFIC...SO THE EXPECTATION IS THAT MUCH OF THE PRECIPITATION WILL BE POST FRONTAL...IN THE DEFORMATION ZONE BEHIND THE SURFACE LOW. WITH THE SOLUTIONS FROM THE GFS/ECMWF/AND NAM-WRF ALL CONVERGING I HAVE NOT HAD TO MAKE MANY ADJUSTMENTS TO THE GOING FORECAST FOR FRIDAY NIGHT INTO SATURDAY. DID KEEP SOME LIKELY POPS ACROSS THE EASTERN HALF OF THE FORECAST AREA FOR SATURDAY EVENING AS THE WEIGHT OF THE CONSENSUS SLOWS THE SYSTEM A LITTLE. OTHERWISE...EXPECT MUCH OF THE PRECIPITATION FALLING FROM THE SKY TO BE SNOW BY THE AFTERNOON HOURS. FREEZING RAIN AND SLEET ARE GOING TO BE MINOR AS THE SPEED WITH WHICH THE COLD AIR RUSHES IN SHOULD PRECLUDE MUCH OPPORTUNITY FOR MIXED PRECIP. CURRENT SNOWFALL TOTALS STILL LOOK RANGE BETWEEN 1 TO 4 INCHES OF ACCUMULATION...IN PART DUE TO THE PROGRESSIVE NATURE OF THE SYSTEM. ALSO...WIND BEHIND THE FRONT LOOKS TO BE SUSTAINED AS HIGH AS 20 TO 30 MPH WITH HIGHER GUSTS. THEREFORE...ADDED BLOWING SNOW TO THE FORECAST WEATHER FOR THE DAY SATURDAY AND SATURDAY NIGHT. CUTTER EXTENDED...(SUNDAY-THURSDAY) THE NORTHERN AND SOUTHERN SHORTWAVE BRANCHES WILL CONTINUE TO PHASE AT THE START OF THE EXTENDED FORECAST ON SUNDAY. THE PHASING SYSTEM WILL QUICKLY DEPART TO THE NORTHEAST...WITH SHORTWAVE RIDGING/SURFACE HIGH PRESSURE SPREADING EAST IN ITS WAKE. A SERIES OF PACIFIC SHORTWAVE TROUGHS WILL CONTINUE TO HEAD EAST THROUGH THE MEAN FLOW ACROSS THE CONUS NEXT WEEK. MODEL AGREEMENT DIMINISHES QUICKLY BY EARLY NEXT WEEK WITH REGARD TO THESE SHORTWAVE FEATURES. AS SUCH...THERE IS LOW CONFIDENCE FOR PRECIPITATION CHANCES. IF ONE MODEL WERE TO BE CHOSEN OVER ANOTHER...WOULD HAVE TO SIDE WITH THE MORE CONSISTENT ECMWF. THE ECMWF STILL BRINGS A CLIPPER SYSTEM FURTHER SOUTH THAN THE GFS ON MONDAY...BUT WITH LITTLE MOISTURE TO WORK WITH MEASURABLE PRECIPITATION IS NOT EXPECTED FOR OUR NECK OF THE WOODS. THE NEXT IN THE SERIES OF PROGRESSIVE SHORTWAVES IS PROGGED TO AFFECT THE REGION TOWARD WEDNESDAY. STOFLET && .AVIATION... FOR THE 06Z TAFS...WILL BRING IN THE DENSER FOG AT 10Z IN THE KANSAS CITY AREA. COULD BE AS EARLY AS 09Z...BUT AM SEEING SOME SIGNS OF THE WESTWARD PROGRESSION SLOWING INTO THE METRO AREA. FOR KSTJ...VSBYS MAY BOUNCE AROUND FOR A WHILE UNTIL THE DENSE FOG AREA CAN MOVE IN. WILL JUST TEMPO THE QUARTER MILE VISIBILITIES AT THIS POINT...AND LET MIDNIGHT SHIFT FINE TUNE AS TIMING IS MORE CERTAIN. PC && .EAX WATCHES/WARNINGS/ADVISORIES... MO...DENSE FOG ADVISORY UNTIL 10 AM FRIDAY FOR MOZ003-MOZ004-MOZ005- MOZ006-MOZ007-MOZ008-MOZ013-MOZ014-MOZ015-MOZ016-MOZ017- MOZ022-MOZ023-MOZ024-MOZ025-MOZ030-MOZ031-MOZ032-MOZ033- MOZ038-MOZ039-MOZ040-MOZ044-MOZ045-MOZ046-MOZ054. DENSE FOG ADVISORY UNTIL 10 AM FRIDAY FOR MOZ001-MOZ002-MOZ011- MOZ012-MOZ020-MOZ021-MOZ028-MOZ029-MOZ037. KS...NONE. $$ mo AREA FORECAST DISCUSSION...CORRECTION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1042 PM CST THU DEC 20 2007 .DISCUSSION... WILL GO AHEAD AND ISSUE A DENSE FOG ADVISORY FOR REST OF FORECAST AREA EXCEPT FOR MIAMI AND LINN COUNTIES IN KANSAS AND CASS AND BATES COUNTIES IN MISSOURI. WILL START THE ADDITIONAL COUNTIES AS OF MIDNIGHT. CURRENT FOG CONTINUES TO SPREAD WESTWARD AT AROUND 5 KTS. DEEPER MOISTURE CAN BE SEEN ON SATELLITE SPREADING INTO NORTHWEST MISSOURI...WHILE FOG IS SHALLOWER BUT STILL STILL PRODUCING LOW VSBYS IN SOUTHWEST MISSOURI. THINK THE SLIGHT INCREASE IN THE LOW LEVEL WINDS LATER TONIGHT WILL HAVE THE MOST IMPACT ON THIS SHALLOWER MOISTURE SO WILL LEAVE EXTREME SOUTHWEST COUNTIES OUT OF THE ADVISORY AT THIS POINT. PC && .PREV DISCUSSION... /850 PM CST THU DEC 20 2007/ DENSE FOG CONTINUES TO SPREAD TO THE WEST UNDER INFLUENCE OF A VERY WEAK SURFACE FLOW AROUND LOW PRESSURE TROUGH IN EASTERN MISSOURI AT THIS TIME. MODELS SHOW THIS TROUGH BREAKING DOWN AS STRONGER TROUGHING IN HIGH PLAINS STARTS TO TAKE SHAPE OVERNIGHT WITH LOW LEVEL FLOW BECOMING SOUTHEAST. THIS SHOULD SLOW THE WESTWARD PROGRESSION AFTER MIDNIGHT BUT MAY SPREAD IT MORE INTO NORTHWEST MISSOURI...WHICH IS ALREADY EXPERIENCING PATCHY DENSE FOG UNDER THE CLEAR SKIES AND LIGHT WINDS. BOTH NAM AND RUC 950 MB DEPICTIONS OF THIS MOISTURE WOULD SUGGEST IT MAKING TO NEAR THE MISSOURI KANSAS BORDER IN NORTHWEST MISSOURI OVERNIGHT AND INTO EASTERN PORTIONS OF THE KANSAS CITY METRO AREA. FOR NOW...WILL GO AHEAD AND EXPAND THE ADVISORY TO INCLUDE AREAS THAT ARE SEEING THE WIDESPREAD DENSE FOG SPREADING IN AT THIS TIME...AND KEEP AN EYE ON THE TRENDS...ADDING COUNTIES AS NEEDED. PC /720 PM CST THU DEC 20 2007/ HAVE MADE SEVERAL PHONE CALLS TO AREAS JUST WEST OF WHERE WE HAD FOG ADVISORY IN EFFECT...AND THEY ARE VERIFYING THE SATELLITE TREND OF THE LOWER VISIBILITIES SPREADING BACK TO THE WEST. WILL EXPAND THE DENSE FOG ADVISORY FURTHER TO THE WEST TO COVER. ESPECIALLY CONCERNED FOR THE INTERSTATES INCLUDING I70 FROM CONCORDIA EASTWARD AND I35 IN HARRISON COUNTY. PC /414 PM CST THU DEC 20 2007/ FORECAST CONCERNS FOR THE FIRST HALF OF THE FORECAST ARE TWO FOLD. TONIGHT WE ARE LOOKING AT CONTINUED DENSE FOG ACROSS AREAS FROM NORTH CENTRAL AND NORTH EAST MISSOURI SOUTH THROUGH CENTRAL MISSOURI. THE SECOND FORECAST CONCERN IS THE WINTER STORM EXPECTED THIS WEEKEND. MOISTURE TRAPPED IN THE BOUNDARY LAYER...AND LIGHT WINDS ASSOCIATED WITH A SURFACE TROUGH...HAVE CONSPIRED TODAY TO KEEP THE EASTERN THIRD OF THE FORECAST AREA UNDER DENSE FOG. CONDITIONS ARE NOT EXPECTED TO CHANGE ACROSS THAT AREA OVERNIGHT. SURFACE TROUGH WILL SLIDE EAST A LITTLE...BUT ONLY ENOUGH TO ALLOW SURFACE WINDS TO SWITCH TO THE SOUTHEAST...ADVECTING MORE MOISTURE IN AT THE SURFACE. HAVE GONE WITH A DENSE FOG ADVISORY FOR THE REST OF THE AFTERNOON THROUGH 10 AM FRIDAY MORNING AS A RESULT. FARTHER WEST SKIES CLEARED TODAY AND THE FOG THAT SET IN DISSIPATED RATHER QUICKLY. TONIGHT WILL SEE THE INVERSION TRAP ABUNDANT MOISTURE AT THE SURFACE AGAIN...BUT WINDS JUST ABOVE THE INVERSION WILL STAY A LITTLE HIGHER IN RESPONSE TO THE DEEPENING TROUGH IN THE WESTERN CONUS. EXPECT THIS SLIGHTLY HIGHER WIND ABOVE THE INVERSION TO INDUCE ENOUGH MIXING OVERNIGHT TO PREVENT THE FOG FROM BECOMING AS DENSE ACROSS THE WESTERN TWO THIRDS OF THE FORECAST AREA. IN FACT...HAVE KEPT FOG OUT OF THE FORECAST FOR AREAS FROM THE KANSAS CITY METRO ON SOUTH AS MODEL SOUNDINGS SHOW THE SURFACE MOISTURE TO BE PARTICULARLY SHALLOW. THIS WILL NEED TO BE WATCHED OVERNIGHT THOUGH IN CASE RADIATION FOG BEGIN TO DEVELOP UNDER THE CLEAR SKIES. ATTENTION THEN TURNS TOWARDS FRIDAY NIGHT AND SATURDAY AS THE DEEPENING WEST CONUS TROUGH SWEEPS EAST THROUGH THE PLAINS. GFS AND ECMWF HAVE CONTINUED TO CONVERGE TOWARDS ONE SOLUTION FOR THIS WEEKENDS SYSTEM...AND THE NAM-WRF SEEMS TO BE MOVING IN THE SAME DIRECTION. THE EARLY WEEKEND SHORTWAVE TROUGH WILL ACTUALLY CONSIST OF A NORTHERN AND SOUTHERN STREAM WAVES PHASING AS THEY THEY MOVE THROUGH MISSOURI. THERE IS A STRONG SHOT OF COLD AIR THAT WILL QUICKLY SPREAD ACROSS THE FORECAST AREA SATURDAY. THIS SYSTEM WILL BE BRINGING THE BULK OF ITS MOISTURE FROM THE PACIFIC...SO THE EXPECTATION IS THAT MUCH OF THE PRECIPITATION WILL BE POST FRONTAL...IN THE DEFORMATION ZONE BEHIND THE SURFACE LOW. WITH THE SOLUTIONS FROM THE GFS/ECMWF/AND NAM-WRF ALL CONVERGING I HAVE NOT HAD TO MAKE MANY ADJUSTMENTS TO THE GOING FORECAST FOR FRIDAY NIGHT INTO SATURDAY. DID KEEP SOME LIKELY POPS ACROSS THE EASTERN HALF OF THE FORECAST AREA FOR SATURDAY EVENING AS THE WEIGHT OF THE CONSENSUS SLOWS THE SYSTEM A LITTLE. OTHERWISE...EXPECT MUCH OF THE PRECIPITATION FALLING FROM THE SKY TO BE SNOW BY THE AFTERNOON HOURS. FREEZING RAIN AND SLEET ARE GOING TO BE MINOR AS THE SPEED WITH WHICH THE COLD AIR RUSHES IN SHOULD PRECLUDE MUCH OPPORTUNITY FOR MIXED PRECIP. CURRENT SNOWFALL TOTALS STILL LOOK RANGE BETWEEN 1 TO 4 INCHES OF ACCUMULATION...IN PART DUE TO THE PROGRESSIVE NATURE OF THE SYSTEM. ALSO...WIND BEHIND THE FRONT LOOKS TO BE SUSTAINED AS HIGH AS 20 TO 30 MPH WITH HIGHER GUSTS. THEREFORE...ADDED BLOWING SNOW TO THE FORECAST WEATHER FOR THE DAY SATURDAY AND SATURDAY NIGHT. CUTTER EXTENDED...(SUNDAY-THURSDAY) THE NORTHERN AND SOUTHERN SHORTWAVE BRANCHES WILL CONTINUE TO PHASE AT THE START OF THE EXTENDED FORECAST ON SUNDAY. THE PHASING SYSTEM WILL QUICKLY DEPART TO THE NORTHEAST...WITH SHORTWAVE RIDGING/SURFACE HIGH PRESSURE SPREADING EAST IN ITS WAKE. A SERIES OF PACIFIC SHORTWAVE TROUGHS WILL CONTINUE TO HEAD EAST THROUGH THE MEAN FLOW ACROSS THE CONUS NEXT WEEK. MODEL AGREEMENT DIMINISHES QUICKLY BY EARLY NEXT WEEK WITH REGARD TO THESE SHORTWAVE FEATURES. AS SUCH...THERE IS LOW CONFIDENCE FOR PRECIPITATION CHANCES. IF ONE MODEL WERE TO BE CHOSEN OVER ANOTHER...WOULD HAVE TO SIDE WITH THE MORE CONSISTENT ECMWF. THE ECMWF STILL BRINGS A CLIPPER SYSTEM FURTHER SOUTH THAN THE GFS ON MONDAY...BUT WITH LITTLE MOISTURE TO WORK WITH MEASURABLE PRECIPITATION IS NOT EXPECTED FOR OUR NECK OF THE WOODS. THE NEXT IN THE SERIES OF PROGRESSIVE SHORTWAVES IS PROGGED TO AFFECT THE REGION TOWARD WEDNESDAY. STOFLET && .AVIATION... /535 PM CST THU DEC 20 2007/ FOR THE 00Z TAF CYCLE...SOUNDINGS SHOW ANOTHER INVERSION SETTING UP ACROSS THE KANSAS/MISSOURI BORDER REGION TONIGHT...WITH A MODEST AND MOIST SOUTHEAST SURFACE FLOW. HOWEVER...THE WIND JUST OFF THE SURFACE IS EXPECTED TO REMAIN A LITTLE STRONGER EARLY FRIDAY MORNING THAN IT WAS THIS MORNING. THOUGHTS ARE THAT THIS WILL KEEP THE SURFACE LAYER MIXED A LITTLE MORE WITH THE DRY LAYER ABOVE PREVENTING A DRASTIC DECREASE IN VISIBILITIES IN THE MORNING. BIGGEST CONCERN WILL BE AT KSTJ WITH ITS SLIGHTLY LOWER ELEVATION ISOLATING IT A BIT MORE FROM THE EFFECTS OF DRIER AIR MIXING IN OVER TOP. WILL GO WITH A TEMPO CATEGORY FOR IFR CONDITIONS LATE TONIGHT AT THAT SITE. PC && .EAX WATCHES/WARNINGS/ADVISORIES... MO...DENSE FOG ADVISORY UNTIL 10 AM FRIDAY FOR MOZ003-MOZ004-MOZ005- MOZ006-MOZ007-MOZ008-MOZ013-MOZ014-MOZ015-MOZ016-MOZ017- MOZ022-MOZ023-MOZ024-MOZ025-MOZ030-MOZ031-MOZ032-MOZ033- MOZ038-MOZ039-MOZ040-MOZ044-MOZ045-MOZ046-MOZ054. DENSE FOG ADVISORY UNTIL 10 AM FRIDAY FOR MOZ001-MOZ002-MOZ011- MOZ012-MOZ020-MOZ021-MOZ028-MOZ029-MOZ037. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 850 PM CST THU DEC 20 2007 .DISCUSSION... DENSE FOG CONTINUES TO SPREAD TO THE WEST UNDER INFLUENCE OF A VERY WEAK SURFACE FLOW AROUND LOW PRESSURE TROUGH IN EASTERN MISSOURI AT THIS TIME. MODELS SHOW THIS TROUGH BREAKING DOWN AS STRONGER TROUGHING IN HIGH PLAINS STARTS TO TAKE SHAPE OVERNIGHT WITH LOW LEVEL FLOW BECOMING SOUTHEAST. THIS SHOULD SLOW THE WESTWARD PROGRESSION AFTER MIDNIGHT BUT MAY SPREAD IT MORE INTO NORTHWEST MISSOURI...WHICH IS ALREADY EXPERIENCING PATCHY DENSE FOG UNDER THE CLEAR SKIES AND LIGHT WINDS. BOTH NAM AND RUC 950 MB DEPICTIONS OF THIS MOISTURE WOULD SUGGEST IT MAKING TO NEAR THE MISSOURI KANSAS BORDER IN NORTHWEST MISSOURI OVERNIGHT AND INTO EASTERN PORTIONS OF THE KANSAS CITY METRO AREA. FOR NOW...WILL GO AHEAD AND EXPAND THE ADVISORY TO INCLUDE AREAS THAT ARE SEEING THE WIDESPREAD DENSE FOG SPREADING IN AT THIS TIME...AND KEEP AN EYE ON THE TRENDS...ADDING COUNTIES AS NEEDED. PC && .PREV DISCUSSION... /720 PM CST THU DEC 20 2007/ HAVE MADE SEVERAL PHONE CALLS TO AREAS JUST WEST OF WHERE WE HAD FOG ADVISORY IN EFFECT...AND THEY ARE VERIFYING THE SATELLITE TREND OF THE LOWER VISIBILITIES SPREADING BACK TO THE WEST. WILL EXPAND THE DENSE FOG ADVISORY FURTHER TO THE WEST TO COVER. ESPECIALLY CONCERNED FOR THE INTERSTATES INCLUDING I70 FROM CONCORDIA EASTWARD AND I35 IN HARRISON COUNTY. PC /414 PM CST THU DEC 20 2007/ FORECAST CONCERNS FOR THE FIRST HALF OF THE FORECAST ARE TWO FOLD. TONIGHT WE ARE LOOKING AT CONTINUED DENSE FOG ACROSS AREAS FROM NORTH CENTRAL AND NORTH EAST MISSOURI SOUTH THROUGH CENTRAL MISSOURI. THE SECOND FORECAST CONCERN IS THE WINTER STORM EXPECTED THIS WEEKEND. MOISTURE TRAPPED IN THE BOUNDARY LAYER...AND LIGHT WINDS ASSOCIATED WITH A SURFACE TROUGH...HAVE CONSPIRED TODAY TO KEEP THE EASTERN THIRD OF THE FORECAST AREA UNDER DENSE FOG. CONDITIONS ARE NOT EXPECTED TO CHANGE ACROSS THAT AREA OVERNIGHT. SURFACE TROUGH WILL SLIDE EAST A LITTLE...BUT ONLY ENOUGH TO ALLOW SURFACE WINDS TO SWITCH TO THE SOUTHEAST...ADVECTING MORE MOISTURE IN AT THE SURFACE. HAVE GONE WITH A DENSE FOG ADVISORY FOR THE REST OF THE AFTERNOON THROUGH 10 AM FRIDAY MORNING AS A RESULT. FARTHER WEST SKIES CLEARED TODAY AND THE FOG THAT SET IN DISSIPATED RATHER QUICKLY. TONIGHT WILL SEE THE INVERSION TRAP ABUNDANT MOISTURE AT THE SURFACE AGAIN...BUT WINDS JUST ABOVE THE INVERSION WILL STAY A LITTLE HIGHER IN RESPONSE TO THE DEEPENING TROUGH IN THE WESTERN CONUS. EXPECT THIS SLIGHTLY HIGHER WIND ABOVE THE INVERSION TO INDUCE ENOUGH MIXING OVERNIGHT TO PREVENT THE FOG FROM BECOMING AS DENSE ACROSS THE WESTERN TWO THIRDS OF THE FORECAST AREA. IN FACT...HAVE KEPT FOG OUT OF THE FORECAST FOR AREAS FROM THE KANSAS CITY METRO ON SOUTH AS MODEL SOUNDINGS SHOW THE SURFACE MOISTURE TO BE PARTICULARLY SHALLOW. THIS WILL NEED TO BE WATCHED OVERNIGHT THOUGH IN CASE RADIATION FOG BEGIN TO DEVELOP UNDER THE CLEAR SKIES. ATTENTION THEN TURNS TOWARDS FRIDAY NIGHT AND SATURDAY AS THE DEEPENING WEST CONUS TROUGH SWEEPS EAST THROUGH THE PLAINS. GFS AND ECMWF HAVE CONTINUED TO CONVERGE TOWARDS ONE SOLUTION FOR THIS WEEKENDS SYSTEM...AND THE NAM-WRF SEEMS TO BE MOVING IN THE SAME DIRECTION. THE EARLY WEEKEND SHORTWAVE TROUGH WILL ACTUALLY CONSIST OF A NORTHERN AND SOUTHERN STREAM WAVES PHASING AS THEY THEY MOVE THROUGH MISSOURI. THERE IS A STRONG SHOT OF COLD AIR THAT WILL QUICKLY SPREAD ACROSS THE FORECAST AREA SATURDAY. THIS SYSTEM WILL BE BRINGING THE BULK OF ITS MOISTURE FROM THE PACIFIC...SO THE EXPECTATION IS THAT MUCH OF THE PRECIPITATION WILL BE POST FRONTAL...IN THE DEFORMATION ZONE BEHIND THE SURFACE LOW. WITH THE SOLUTIONS FROM THE GFS/ECMWF/AND NAM-WRF ALL CONVERGING I HAVE NOT HAD TO MAKE MANY ADJUSTMENTS TO THE GOING FORECAST FOR FRIDAY NIGHT INTO SATURDAY. DID KEEP SOME LIKELY POPS ACROSS THE EASTERN HALF OF THE FORECAST AREA FOR SATURDAY EVENING AS THE WEIGHT OF THE CONSENSUS SLOWS THE SYSTEM A LITTLE. OTHERWISE...EXPECT MUCH OF THE PRECIPITATION FALLING FROM THE SKY TO BE SNOW BY THE AFTERNOON HOURS. FREEZING RAIN AND SLEET ARE GOING TO BE MINOR AS THE SPEED WITH WHICH THE COLD AIR RUSHES IN SHOULD PRECLUDE MUCH OPPORTUNITY FOR MIXED PRECIP. CURRENT SNOWFALL TOTALS STILL LOOK RANGE BETWEEN 1 TO 4 INCHES OF ACCUMULATION...IN PART DUE TO THE PROGRESSIVE NATURE OF THE SYSTEM. ALSO...WIND BEHIND THE FRONT LOOKS TO BE SUSTAINED AS HIGH AS 20 TO 30 MPH WITH HIGHER GUSTS. THEREFORE...ADDED BLOWING SNOW TO THE FORECAST WEATHER FOR THE DAY SATURDAY AND SATURDAY NIGHT. CUTTER EXTENDED...(SUNDAY-THURSDAY) THE NORTHERN AND SOUTHERN SHORTWAVE BRANCHES WILL CONTINUE TO PHASE AT THE START OF THE EXTENDED FORECAST ON SUNDAY. THE PHASING SYSTEM WILL QUICKLY DEPART TO THE NORTHEAST...WITH SHORTWAVE RIDGING/SURFACE HIGH PRESSURE SPREADING EAST IN ITS WAKE. A SERIES OF PACIFIC SHORTWAVE TROUGHS WILL CONTINUE TO HEAD EAST THROUGH THE MEAN FLOW ACROSS THE CONUS NEXT WEEK. MODEL AGREEMENT DIMINISHES QUICKLY BY EARLY NEXT WEEK WITH REGARD TO THESE SHORTWAVE FEATURES. AS SUCH...THERE IS LOW CONFIDENCE FOR PRECIPITATION CHANCES. IF ONE MODEL WERE TO BE CHOSEN OVER ANOTHER...WOULD HAVE TO SIDE WITH THE MORE CONSISTENT ECMWF. THE ECMWF STILL BRINGS A CLIPPER SYSTEM FURTHER SOUTH THAN THE GFS ON MONDAY...BUT WITH LITTLE MOISTURE TO WORK WITH MEASURABLE PRECIPITATION IS NOT EXPECTED FOR OUR NECK OF THE WOODS. THE NEXT IN THE SERIES OF PROGRESSIVE SHORTWAVES IS PROGGED TO AFFECT THE REGION TOWARD WEDNESDAY. STOFLET && .AVIATION... /535 PM CST THU DEC 20 2007/ FOR THE 00Z TAF CYCLE...SOUNDINGS SHOW ANOTHER INVERSION SETTING UP ACROSS THE KANSAS/MISSOURI BORDER REGION TONIGHT...WITH A MODEST AND MOIST SOUTHEAST SURFACE FLOW. HOWEVER...THE WIND JUST OFF THE SURFACE IS EXPECTED TO REMAIN A LITTLE STRONGER EARLY FRIDAY MORNING THAN IT WAS THIS MORNING. THOUGHTS ARE THAT THIS WILL KEEP THE SURFACE LAYER MIXED A LITTLE MORE WITH THE DRY LAYER ABOVE PREVENTING A DRASTIC DECREASE IN VISIBILITIES IN THE MORNING. BIGGEST CONCERN WILL BE AT KSTJ WITH ITS SLIGHTLY LOWER ELEVATION ISOLATING IT A BIT MORE FROM THE EFFECTS OF DRIER AIR MIXING IN OVER TOP. WILL GO WITH A TEMPO CATEGORY FOR IFR CONDITIONS LATE TONIGHT AT THAT SITE. PC && .EAX WATCHES/WARNINGS/ADVISORIES... MO...DENSE FOG ADVISORY UNTIL 10 AM FRIDAY FOR MOZ003-MOZ004- MOZ005-MOZ006-MOZ007-MOZ008-MOZ013-MOZ014-MOZ015-MOZ016- MOZ017-MOZ022-MOZ023-MOZ024-MOZ025-MOZ030-MOZ031-MOZ032- MOZ033-MOZ038-MOZ039-MOZ040-MOZ044-MOZ045-MOZ046-MOZ054. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 835 PM MST FRI DEC 21 2007 .SHORT TERM...VALID FOR SAT AND SUN... UPDATE FOR FORECAST THIS EVENING. NO UPDATE TO AFP. FORECAST IN GOOD SHAPE TONIGHT AND WILL ONLY BE MAKING MINOR ADJUSTMENTS. DRIER AIR IS PUSHING INTO THE AREA FROM THE NORTHWEST AND HAVE REMOVED POPS OVER THE NORTHWEST ZONES. HAVE ALSO REMOVED POPS OVER THE FAR SOUTHEAST ZONES AS UPPER TROUGH IS EXITING THE AREA WITH SUBSIDENCE SETTING UP BEHIND THE WAVE. BIGGEST CHALLENGE TONIGHT IS TEMPERATURES. DEW POINT TEMPERATURES IN THE SINGLE DIGITS JUST TO THE NORTH OF THE FORECAST AREA AND WILL SINK SOUTHEAST OVERNIGHT. SURFACE PRESSURE GRADIENT ALSO WEAKENING WITH EXITING WAVE WHICH WILL ALLOW FOR LIGHTER WINDS. HAVE LOWERED TEMPERATURES ACROSS THE EASTERN AREAS WHERE THE COLDEST AIR IS EXPECTED OVERNIGHT. DID NOT CHANGE TEMPERATURES OVER THE CENTRAL AND WESTERN ZONES AS 00Z RUC13 AND NAM SHOWING WARM AIR ADVECTION TAKING PLACE AT 700MB AND 850MB. RICHMOND .LONG TERM...VALID FOR MON...TUE...WED...THU...FRI... MOST OF THE EXTENDED EMPHASIS ON MONDAY SYSTEM AS GFS AND OTHER MODELS ARE LOOKING PRETTY SOLID ON THE TRACK OF THE SYSTEM. STILL A PROGRESSIVE FLOW PATTERN WITH A SERIES OF HIGHER AMPLITUDE WAVES PROGGED TO MOVE ACROSS THE AREA. MONDAY SYSTEM DIGS THE MAIN SHORTWAVE ENERGY OVER IDAHO INTO UTAH WITH A COLD FRONT MOVING ACROSS MONTANA. IT LOOKS LIKE THE LATEST GFS IS PICKING UP ON SOME SURFACE WAVE DEVELOPMENT ALONG THE FRONT IN SOUTHERN MONTANA DUE TO A BETTER ARCTIC SURGE. GFS AND WRF ARE IN AGREEMENT WITH TIMING WHILE THE ECWMF IS ABOUT 6 TO 8 HOURS FASTER. IT MAY BE THAT THIS ALLOWS A BIT MORE WARMING IN ADVANCE OF THE FRONT AND SETS UP A BETTER BAROCLINIC REGION WITH SURFACE WAVE DEVELOPMENT. HAVE UPPED POPS ACROSS THE AREA AND WHILE DYNAMICS ARE NOT REAL IMPRESSIVE MOISTURE SHOULD BE VERY DEEP AS AN ACTIVE PACIFIC PATTERN COULD BRING DECENT PRECIPITABLE WATERS INTO THE STORM. HAVE NOT ADJUSTED TEMPERATURES AS GUIDANCE SPREAD FOR MONDAY RANGES FROM 32 TO 46 DEGREES WITH TIMING CRITICAL TO MAX TEMPERATURE. BOTTOM LINE IS THAT SNOWFALL IS POSSIBLE ON MONDAY WHICH MAY SLOW DOWN TRAVEL TIMES ON THE EVE OF THE HOLIDAY. SNOW SHOULD CONTINUE INTO MONDAY NIGHT WITH A RIDGE RAPIDLY MOVING INTO THE AREA TUESDAY MAKING IT A DRY DAY BUT COOLER WITH LEESIDE PRESSURE GRADIENTS NOT BECOMING DOWNSLOPISH UNTIL LATE TUESDAY NIGHT. WEDNESDAY HAS GOOD AGREEMENT THAT ANOTHER SYSTEM TRACKS THROUGH THE AREA BUT AGAIN TRACK IS MAINLY SOUTH AND WEST OF THE AREA SO MUCH WILL DEPEND ON SURFACE WAVE DEVELOPMENT. PATTERN SLOWS DOWN AT THIS POINT WHERE TROUGHINESS REMAINS OVER THE AREA FOR THURSDAY WITH CONTINUED COOLING AND TEMPERATURES REMAINING IN THE 20S...DEPENDING ON HOW MUCH SNOW IS ACCUMULATED BY THIS POINT. FRIDAY SEES RIDGING MOVE ACROSS THE AREA WITH SOUTHWEST FLOW ALOFT FOR EARLY NEXT WEEKEND. THIS MAY ALLOW A LONGER LIVED DOWNSLOPE FLOW PATTERN TO DEVELOP BRINING MODERATION. BORSUM && .AVIATION... SKIES WILL BE CLEAR TO PARTLY CLOUDY OVERNIGHT WITH VFR CONDITIONS PREVAILING ACROSS THE PLAINS. HOWEVER...A FEW SNOW SHOWERS WILL BE POSSIBLE OVER THE BEARTOOTH/ABSAROKA MOUNTAINS WITH A FEW AREAS OF MVFR CONDITIONS AND MOUNTAIN OBSCURATIONS. SOME PATCHY FOG IS POSSIBLE ACROSS AREAS WITH A SNOW COVER...BUT MAINLY ALONG AND A FEW MILES EITHER SIDE OF THE YELLOWSTONE RIVER. HOOLEY && .PRELIMINARY POINT TEMP/POPS... SAT SUN MON TUE WED THU FRI ----------------------------------------------------------- BIL 011/028 018/034 023/040 024/033 019/032 017/032 016/032 00/U 20/B 04/S 42/S 00/U 00/B 00/U LVM 008/024 020/031 024/033 021/032 016/032 018/032 015/032 10/N 33/S 04/S 52/S 02/S 10/B 02/S HDN 012/029 012/034 018/038 021/034 015/032 015/032 014/032 00/U 00/B 02/S 42/S 00/U 00/B 00/B MLS 008/026 008/029 014/038 020/032 014/032 011/033 012/033 00/U 00/B 01/B 31/B 00/U 00/B 00/B 4BQ 006/027 008/029 014/037 019/033 013/028 010/030 013/030 00/U 01/B 00/B 32/S 00/U 01/B 00/B BHK 005/020 004/024 007/034 015/031 010/027 008/031 011/031 00/U 00/B 00/B 22/S 00/B 00/B 00/B SHR 006/026 009/029 013/037 020/032 012/028 011/033 012/033 00/U 12/S 02/S 42/S 00/U 01/B 01/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1121 AM EST FRI DEC 21 2007 .SYNOPSIS... MARINE MOISTURE WILL RIDE UP THE MOUNTAINS OF NORTHEASTERN PENNSYLVANIA, AND BRING CLOUDS AND PATCHY FREEZING DRIZZLE TO THE REGION TONIGHT. LOW PRESSURE WILL SPREAD STRONG WINDS AND RAIN INTO NY AND PA FOR SUNDAY. BEHIND THE STORM WILL BE COLDER AIR AND LAKE EFFECT SNOW SHOWERS SUNDAY NIGHT INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... LOW LEVEL SOUTHEAST FLOW OFF OF ATLANITC KEEPING CLOUDS OVER MOST OF THE CWA TODAY INTO SATURDAY. WITH THE THICK LOW CLOUDS DROPPED THE HIGH TEMPERATURES BY A FEW DEGREES. FEW OTHER CHANGES TO THE NEAR TERM. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... MAIN CONCERN IN THE NEAR TERM IS FOR PATCHY FREEZING DRIZZLE OVERNIGHT, AND EARLY SATURDAY. MARINE LAYER MOISTURE WILL FLOW NORTHWEST THROUGH PA TONIGHT. THE BEST CHANCE FOR FREEZING DRIZZLE WILL BE JUST NORTH OF THE HIGH TERRAIN IN NORTHEASTERN PA, AND ALSO INTO DELAWARE AND OTSEGO COUNTIES, WHERE THE ADDED LIFT SHOULD ALLOW FOR SOME LIGHT DRIZZLE. WE BRING CHC POPS INTO NY/PA SATURDAY AFTERNOON WITH WARM FRONTAL PUSH, THEN QUICKLY RAMP POPS SATURDAY NIGHT INTO SUNDAY. MODELS ARE IN GOOD AGREEMENT REGARDING MOISTURE FLOW AND LIFT. THERE ARE SOME QPF DISCREPANCIES, WHICH COULD COME INTO PLAY ON SUNDAY. WITH 1.50-2.00 INCHES OF LIQUID IN THE SNOW PACK MAINLY EAST OF I-81, AND AN ADDITIONAL 0.75-1.50 INCHES OF PRECIPITATION EXPECTED, THERE IS A POSSIBILITY FOR HYDRO CONCERNS. GIVEN THE STRENGTH OF THE WINDS, THE HIGH DEW POINTS, AND THE MILD TEMPERATURES OVER AN EXTENDED PERIOD OF TIME, A LOT OF SNOW PACK COULD BE MELTED TO RELEASE ITS WATER CONTENT. && .LONG TERM /MONDAY THROUGH THURSDAY/... MEDIUM RANGE GUIDANCE IN GOOD AGREEMENT WITH FEATURES BEHIND THE STRONG LOW PRESSURE AND COLD FROPA SUNDAY NIGHT. CYCLONIC FLOW ALOFT AND CAA ACROSS LAKE ONTARIO WILL MAINTAIN PLENTY OF CLOUDS AND LAKE EFFECT SNOW STREAMERS. MODELS DIVERGE TUES AND WEDNESDAY. ALL MODELS AGREE ON HIGH AMPLITUDE TROF DEVELOPING OVER INTERMOUNTAIN WEST...BUT THE LAST FEW RUNS OF GFS SEEM TO BE OUT ON THEIR OWN WITH MAINTAINING A STRONG RIDGE OVER THE SW ATLANTIC AND SE CONUS.THE GEFS/EC/GGEM/UKMET CAMP...AND EVEN NOGAPS SHOW SOME NRN/SRN STREAM PHASING OF UL LOW PRESSURE OVER THE SOUTHEASTERN STATES ON TUESDAY AND WEDNESDAY. THIS LEADS TO SIGNIFICANT CYCLOGENESIS OFFSHORE. THAT SAID...THIS DOES NOT SEEM TO HAVE MUCH BEARING ON CNY/NEPA WEATHER FOR THE MIDDLE OF NEXT WEEK...BARRING A SIGNIFICANT WWD SHIFT IN MODEL TRACKS OF THE LOW FEATURE. BOTH MODEL CAMPS OFFER UP AT LEAST SOME DERIVATION OF HIGH PRESSURE FORMING OVER THE NORTHEAST WITH FAIR WX BOTH CHRISTMAS DAY...AND WEDNESDAY AND WILL GO WITH THAT FOR NOW. THURSDAY ALSO BECOMES ANOTHER PROBLEM WITH MORE MODEL SPREAD. GFS AND IT/S GEFS ENSEMBLES LIFTS OUT THE INTERMOUNTAIN WEST LOW BY THURSDAY...WHILE EC SEEMS TO HOLD BACK A COUPLE DAYS. CAN GGEM WOULD SUGGEST SOME PRECIP AS EARLY AS THURS. PREV FCST INDICATES CHC...AND WILL STICK WITH THAT CONSIDERING OVERALL LOW PRESSURE INDICATED OVER UPR MIDWEST/GTLKS BY DAY 7 HPC PROG. PRETTY MUCH WENT WITH WHAT 00Z GMOS HAS OFFERED FOR TEMPS. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... ANOTHER DAY...MORE CRAZY FLIGHT CONDITIONS IN CNY/NEPA. LATEST FOG PRODUCT SHOWS PLENTY OF HOLES HAD DEVELOPED IN THE STRATUS LAYER BETWEEN 08Z-11Z...WITH CIGS SCATTERING OUT TO VFR AT BGM-ELM-ITH- RME. ON THE FLIP SIDE...THIS CLEARING HAS ALLOWED MVFR AND BRIEF IFR VSBYS TO DEVELOP. MEANWHILE...MARINE LAYER STRATUS WAS NOT THAT FAR AWAY...AND HAS INVADED AVP WITH MVFR CIGS. NOT EXACTLY SURE WHY ALL THIS HAS TRANSPIRED...BUT COULD BE THAT SELY BLYR FLOW HAS INCREASED WITH A LITTLE DOWNSLOPING WAS OCCURRING FROM THE CATSKILLS AND POCONOS WAS AFFECTING BGM-ELM-ITH...WHILE MOISTURE WAS INCRG ON THE LEE SIDE AT AVP. RUC AND NAM MODELS DO SEEM TO BE CAPTURING THIS IN THE 925 MB RH FIELDS...AND BOTH SUGGEST THAT BKN-OVC MVFR CIGS FROM THE MARINE LAYER WILL RETURN TO THE CLEARED OUT AREAS BY 15Z. SYR REMAINS SOCKED IN LIFR CIG. THINKING IS THAT THEY TOO WILL LIFT THE LOW LAYER TO MVFR BY 13Z OR 14Z. ONCE THE MARINE STRATUS LAYER IS IN...IT IS PROGGED TO STAY THROUGH THIS PERIOD WITH MINOR FLUCTUATIONS. ALSO EXPECT AS LAYER COOLS TONIGHT SOME WEAK UPSLOPE LIFT MAY CAUSE IFR CIGS AGAIN WITH FREEZING DRIZZLE AT AVP AND BGM...WITH LESS OF A CHC AT ELM-ITH AND VRY LITTLE CHC AT RME-SYR. CONFIDENCE IN THE DETAILS OF THIS FCST AT ANY STATION IS VERY LOW...NOT A GOOD DAY FOR VFR ONLY RATED AVIATORS. HIGH PRESSURE STRENGTHENS A LITTLE ON SATURDAY WITH MODELS SHOWING DRYING OF THE LOW LVLS IN THE AFTERNOON. THIS SHOULD AT LEAST ALLOW CIGS TO REACH VFR. THEN...THE NEXT STORM SYSTEM APPCHS LATE SATURDAY NIGHT WITH PCPN DEVELOPING AFTER 06Z SUNDAY. RAIN EXPECTED ON SUNDAY BEFORE STRONG COLD FRONTAL PASSAGE TOWARD EVENING...WITH PRECIPITATION CHANGING OVER TO ALL SNOW. EXPECT VARIABLE MVFR-IFR CIG RESTRICTIONS ON SUNDAY AND SUNDAY NIGHT. WINDS INCREASE OUT OF THE SOUTHEAST SUNDAY MORNING WITH LOW-LEVEL WINDS OF 50+ KTS DURING THE DAY ON SUNDAY WITH LLWS POSSIBLE...FOLLOWED BY BLUSTERY WEST-NW WINDS POST FROPA ON SUNDAY NIGHT. COLD ADVECTIVE NORTHWEST FLOW WILL CAUSE LAKE EFFECT ON MONDAY AND MONDAY NIGHT WITH STRATOCUMULUS MVFR/IFR CIGS...AND ALSO POOR VSBY IN SHSN. HIGH PRESSURE BEGINNING TO BUILD IN ON TUESDAY WILL SHUT LAKE EFFECT OFF BY MID-WEEK. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...TAC NEAR TERM...TAC SHORT TERM...DJP LONG TERM...JAB AVIATION...JAB ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BISMARCK ND 337 PM CST FRI DEC 21 2007 .SHORT TERM... THE FCST IS CERTAINLY COMPLICATED TODAY...BUT ONCE AGAIN SPLIT FLOW ALOFT HAS SHOWN ITSELF NOT TO BE A MAJOR SNOW PRODUCER IN THIS AREA. THE 12Z GFS GETS OUR NOD PER ITS INITIALIZATION OF THE UPPER LOW IN ALBERTA AT 12Z AND ITS HANDLING OF THE PRECIP BAND WORKING INTO CENTRAL ND AS OF 21Z. HOWEVER...ITS QPF AMOUNTS ARE MUCH TOO HIGH WITH LACK OF MORE FOCUSED DEEP LAYERED ASCENT...AND HENCE WE HAVE CUT THIS BACK. WINTER WEATHER HEADLINES REMAIN THE CONCERN INTO THE EVE WITH TRAVEL IMPACTS...BUT TEMPS BECOME THE MAIN ISSUE OVER THE WEEKEND. LOOKING THROUGH MODEL DIAGNOSTICS TELLS US WHY SNOW HAS NOT BEEN AS INTENSE AS QPF WOULD SHOW...WITH THE PRIMARY QG FORCING ACROSS THE FA RATHER DISJOINTED...AND FOCUSED IN WSTRN SD WHERE CLOUD TOPS HAVE COOLED MOST TODAY. WE ALSO LACKED JET DYNAMICS WITH A DOMINANT SRN STREAM...AND ISENTROPIC LIFT WAS ALSO MINIMIZED. MOST UPWARD VERTICAL MOTION HAS COME VIA DIFFERENTIAL PVA ALOFT COURTESY THE SE-MOVING UPPER LOW NOW IN CENTRAL SASKATCHEWAN. THERMAL FORCING IS NOT FAVORABLE...HENCE THE POOR DEEP LAYER Q-VECTOR RESPONSE. THE 12Z GFS AND MORE RECENT RUC RUNS HAVE HOWEVER CAUGHT THE BAND OF SNOW SPREADING JUST AHEAD OF THE PRIMARY CAA INTO CENTRAL ND. WE GOT 1-3 INCHES OF SNOW IN THIS BAND AND SINCE IT IS PROGRESSIVE DO NOT EXPECT MUCH MORE THAN THAT. SNOW RATIOS WILL WILL DROP AS STRONG 925-850MB CAA CONTINUES INTO THE EVE...BUT PWATS ALSO DROP TO 0.25 INCHES IN THE 50-75NM ZONE BEHIND THE PRIMARY LOW LEVEL BAROCLINIC ZONE. THE MAIN ISSUE IS GOING TO BE BLSN...WITH 30KT GUSTS COMMON ACROSS SW ND ALREADY. GFS BUFR SOUNDINGS SHOW 30-35KTS AT THE TOP OF THE MIXED LAYER INTO THIS EVE SO WE WILL CONTINUE TO GET THESE GUSTS AT THE SFC...BUT THE PRIMARY ISALLOBARIC COMPONENT /3-HOUR PRESSURE RISE CENTER OF ONLY 3MB AS OF 21Z/ HAS WEAKENED THE PAST 6 HOURS. WITH FALLING SFC TEMPS AND BLOWING/DRIFTING...ROADS WILL BE SLICK AND HENCE WE WILL CONTINUE WITH THE SN/BS ADVZY. WE DID HOWEVER UTILIZE THE 12Z GFS TIMING OF THE SNOW BAND TO DROP THE ADVZY IN THE WEST AT 02Z...THE CENTRAL AT 06Z...AND HUNG ON TO THE HEADLINE IN THE JMS AREA UNTIL 12Z. KDIK HAS OCCASIONALLY BEEN DOWN 1SM THE PAST FEW HOURS SO EVEN BEHIND THE PRIMARY SN BAND SOME TRAVEL PROBLEMS WILL CONTINUE. DRY AIR AHEAD OF THE SFC HIGH HAS WORKED INTO NW ND THOUGH SO WE WILL DROP THE ADVZY FROM NW ND. THE UPPER VORT DROPS INTO CENTRAL ND SAT AND THE COLUMN COOLS DRASTICALLY WITH 850MB TEMPS DOWN TO -20 C. THERE WILL STILL BE SOME MIXING WITH PROG SOUNDINGS SHOWING 25KTS TO BRING TO THE SFC...BUT THIS WILL DO NOTHING FOR THE TEMP RISE. WE UNDERCUT GUIDANCE CONSIDERABLY GIVEN THE STRENGTH OF COOLING AND APPROACH OF THE SFC HIGH...AND ADDITION OF SOME SNOW PACK...ALBEIT MINOR IN MOST SPOTS. THE SAME GOES FOR SUNDAY...WHEN MIXING WILL BE EVEN MORE LIMITED WITH THE SFC RIDGE AXIS SITTING ON TOP OF US. WIND CHILLS WILL BE A PROBLEM...PERHAPS AS EARLY AS LATE TONIGHT...AND MORE LIKELY LATER ON SATURDAY. HOWEVER...WE WILL STOP SHORT OF ISSUING THOSE HEADLINES FOR NOW IN ORDER TO AVOID CONFUSION WITH THE PRESENT EVENT. S/W RIDGING PROGRESSES ACROSS THE NRN PLAINS ON MON AHEAD OF THE NEXT TROUGH STILL SET TO APPROACH BY 12Z TUE. THE 12Z GFS IS A BIT MORE AGGRESSIVE WITH HEIGHT FALLS WITH THIS NEXT SYSTEM...SO A CHANCE OF SNOW IS IN THE CARDS IN WSTRN ND. AGAIN THOUGH THE ENERGY WILL BE SPLIT AND HENCE CONFIDENCE IN GETTING MUCH OUT OF THE SYSTEM IS LOW. .LONG TERM... FEW CHANGES IN THE LONG TERM PERIOD TODAY. THE ECMWF AND GFS ARE IN FAIR AGREEMENT AND HPC WENT MAINLY WITH THE ECMWF FOR DETAILS. KEPT MENTION OF LIGHT SNOW TUESDAY WITH LONGWAVE TROUGH EXTENDING FROM THE MAIN LOW IN NORTH CENTRAL CANADA AND ANOTHER LOW IN THE SOUTHERN PLAINS. THE ECMWF CUTS OFF THE SOUTHERN LOW FROM THE WESTERLIES...WHILE THE GFS KEEPS THE LONGWAVE TROUGH MAINTAINED AS THE SYSTEMS MOVE EAST ACROSS CENTRAL NORTH AMERICA. AFTER THIS...THE STATE REMAINS BETWEEN LOWS THAT TRACK ACROSS CANADA AND LOWS TRACKING ACROSS THE SOUTHERN PART OF THE CONUS. THIS WILL KEEP THE FORECAST DRY WITH NO BIG ARCTIC OUTBREAKS BUT ALSO NO WARM-UPS FROM THE SOUTHWEST. EXPECTING HIGHS IN THE TEENS AND 20S WITH LOWS 5 TO 15 ABOVE - CLOSE TO AVERAGE FOR THIS TIME OF YEAR. && .AVIATION... SURFACE LOW PRESSURE OVER EASTERN NEBRASKA WITH AN INVERTED TROUGH EXTENDING FROM THE LOW INTO THE RED RIVER VALLEY OF NORTH DAKOTA. GUSTY NORTHWEST WINDS OVER WESTERN AND CENTRAL NORTH DAKOTA WITH AREAS OF SNOW AND BLOWING SNOW CENTRAL. THIS SNOW EXPECTED TO PERSIST THROUGH 02Z TO 05Z. THE BACK EDGE OF THE CLOUDS WITH DRY AIR IS MOVING INTO NORTHWESTERN NORTH DAKOTA AT THIS TIME. EXPECT FALLING SNOW TO END OVER CENTRAL NORTH DAKOTA BY AROUND 03Z. MVFR AND IFR CEILINGS AND VSBYS TO IMPROVE TO VFR OVER WESTERN ROUTES BY 02Z AND OVER CENTRAL NORTH DAKOTA BY 06Z...BUT PERSIST UNTIL 12Z IN THE RED RIVER VALLEY. ANOTHER MVFR/IFR CLOUD SHIELD EXPECTED TO MOVE INTO NORTHWESTERN NORTH DAKOTA AFTER 06Z AND SPREAD TO CENTRAL NORTH DAKOTA BY 12Z. && .BIS WATCHES/WARNINGS/ADVISORIES... SNOW AND BLOWING SNOW ADVISORY UNTIL MIDNIGHT CST /11 PM MST/ TONIGHT FOR NDZ003>005-011>013-019>022-034-035-042-045-046. SNOW AND BLOWING SNOW ADVISORY UNTIL 8 PM CST /7 PM MST/ THIS EVENING FOR NDZ018-031>033-040-041-043-044. SNOW AND BLOWING SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR NDZ023-025-036-037-047-048-050-051. && $$ CJS/HW/JV nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 930 AM CST THU DEC 20 2007 .SHORT TERM... ONCE AGAIN TEMPERATURES AND FOG CONTINUE BE FORECAST CHALLENGES FOR REMAINDER OF DAY. PATCHY BR...LOCALLY DENSE...PERSISTS FROM RED RIVER VALLEY INTO NW MN. ASSOCIATED STRATUS DECK LOOKS TO BE EXPANDING ACROSS NW MN AND BEING TRAPPED UNDER SHARP INVERSION MAY BE TOUGH TO ERODE. WILL AGAIN EXTEND BR THROUGH AM HOURS AND HOPE INCREASING MIXING WILL DISSIPATE MOST FOG. REMAINDER OF FA SHOULD SEE FAIR AMOUNT OF SOLAR WITH ONLY UPSTREAM SCT-BKN CI/AC. TEMPERATURES WILL ALSO POSE CHALLENGES. COLDEST READINGS THIS AM WEST OF VALLEY WHERE SKIES WERE CLEAR. WEAK WARM ADVECTION CONTINUES TODAY WITH RUC INDICATING AN INCREASE IN MIXING AS SURFACE GRADIENT TIGHTENS A BIT. WITH WARM COLUMN AND SOLAR WESTERN AREAS SHOULD NOT HAVE ANY PROBLEM REACHING FORECAST HIGHS. MAX TEMPERATURES OVER REMAINDER OF FA UNDER BR AND STRATUS WILL HINGE ON MIXING/SOLAR. BEING PESSIMISTIC AREAS ADJACENT TO VALLEY IN NW/WEST CENTRAL MN MAY SEE LIMITED RECOVERY WITH FAR EAST ALREADY CLOSE TO EXPECTED HIGHS BUT NOT LIKELY TO SEE MUCH IMPROVEMENT IN LOW CIGS. WILL LOWER MAX TEMPERATURES SLIGHTLY ACROSS MN ADJACENT TO VALLEY AND LEAVE REMAINDER AS IS. && .AVIATION... IFR/MVFR CIGS/VSBY FROM VALLEY EAST. MODELS SUGGEST INCREASED MIXING WHICH MAY IMPROVE VSBYS IN BR LATE AM INTO EARLY AFTERNOON. NOT QUITE AS CONFIDENT IN LOSING LOWER CIGS OVER MN. MOISTURE REMAINS TRAPPED BLO SHARP INVERSION AND CONFIDENCE NOT REAL HIGH ON CIGS ERODING. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ VOELKER nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1240 AM EST FRI DEC 21 2007 .SYNOPSIS... WEAK HIGH PRESSURE WILL GIVE WAY TO AN AREA OF LOW PRESSURE TONIGHT. COOL AND UNSETTLED NORTHEAST FLOW WILL REMAIN INTO THE WEEKEND AS A WEDGE OF HIGH PRESSURE LINGERS. A COLD FRONT IS EXPECTED TO CROSS THE AREA ON SUNDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... MOST OF THE SIGNIFICANT PRECIPITATION DURING THE REMAINDER OF THE OVERNIGHT PERIOD WILL REMAIN WELL TO THE SOUTH OF THE CWA IN THE VICINITY OF THE SURFACE LOW PRESSURE SYSTEM MOVING EASTWARD ALONG THE GULF COAST TOWARD NORTHERN FL. RUC DEPICTS SOME LIGHT RAIN SPREADING ACROSS EXTREME NORTHEAST GA AND WESTERN CAROLINAS BETWEEN 05Z AND 08Z AS SHORT WAVE TROUGH APPROACHES AND ISENTROPIC LIFT STRENGTHENS A LITTLE OVER SOUTHERN PERIPHERY OF HIGH PRESSURE SYSTEM EXTENDING SOUTHWARD FROM EASTERN CANADA AND NEW ENGLAND. OVERNIGHT FORCING IS RATHER WEAK AND CURRENT RADAR DEPICTION SHOWS THAT EXISTING PRECIPITATION IS NOT EXTENSIVE IN COVERAGE. SO... HAVE LOWERED POPS SOMEWHAT FROM PREVIOUS FORECAST BUT MOST OF CWA WILL STILL HAVE LIKELY OR CATEGORICAL. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/... AS OF 200 PM THURSDAY...PRECIPITATION FROM SOUTHERN STREAM SHORT WAVE AND ATTENDANT SURFACE LOW WILL BE AFFECTING THE FORECAST AREA FRIDAY MORNING. HOWEVER...EXPECT RAINFALL TO BE ON THE LIGHT SIDE AS BEST FORCING WILL BE TO THE SOUTH. ALSO...EXPECT THAT CONVECTION TO THE SOUTH WILL ROB MOISTURE INFLUX. NEVERTHELESS...IT LOOKS LIKE WIDESPREAD LIGHT RAIN (CATEGORICAL POPS) WILL BE OVER THE SOUTHERN PIEDMONTS EARLY FRIDAY...BUT WILL TAPER POPS OFF RAPIDLY TO THE NORTH. THIS SYNOPTIC SCALE PRECIP WILL MOVE OUT THE REGION BY MIDDAY AS SHORT WAVE MOVES OFF THE SE COAST. HOWEVER...NO CLEARING IS EXPECTED AS COLD HIGH OVER NEW ENGLAND WEDGES SOUTHWARD ALONG AND EAST OF THE APPALACHIANS. MODELS INDICATE THAT CAD WILL PERSIST THROUGH SAT ALONG WITH WEAK UPSLOPE COMPONENT IN THE MOUNTAINS.. HENCE...EXPECT CLOUDY CONDITIONS TO PREVAIL THROUGH SAT. AREAS OF LIGHT RAIN/DRIZZLE ARE A GOOD BEST ALONG THE ESCARPMENT THROUGH SAT. PATCHY DRIZZLE A GOOD BET ELSEWHERE FRI NIGHT. BETTER UPSLOPE COMPONENT AND MOISTURE TRANSPORT WILL SUPPORT INCREASING CHANCES OF RAIN...ESPECIALLY OVER THE MOUNTAINS SAT NIGHT. APPROACHING COLD FRONT LATE SAT NIGHT WILL ALSO BOOST PRECIP CHANCES IN THE MOUNTAINS. WILL STAY ON THE LOW END OF GUIDANCE FOR MAX TEMPS BOTH FRI AND SAT. TEMPS WILL PROBABLY SHOW A NON-DIURNAL TREND SAT NIGHT AS CAD ERODES AND WARM ADVECTION KICKS IN. USED 3 HOURLY GMOS TO POPULATE TEMPERATURE GRIDS WHICH KEEPS SAT NIGHT LOWS ESSENTIALLY IN THE UPPER 40S EAST OF THE MOUNTAINS AND LOW TO MID 40S IN MOUNTAINS. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 230 PM THURSDAY...NAM/GFS IN GOOD AGREEMENT THAT COLD FRONT WILL CROSS THE FORECAST AREA ON SUNDAY. HIGHEST POPS WILL BE IN THE MOUNTAINS (LIKELY FOR NOW) WITH CHANCE POPS TO THE EAST. THERE MAY BE ENOUGH FORCING FOR WIDESPREAD SHOWERS EVERYWHERE...BUT FOR NOW WILL JUST SHOW CHANCE TYPE POPS TO EAST OF THE MOUNTAINS AS FLOW DOES VEER TO THE SW WHICH MAY TEND TO DIMINISH SHOWER CHANCES E OF MOUNTAINS. EXPECT RAPID CLEARING BEHIND THE FRONT BY SUN EVENING. HIGH PRESSURE WILL BUILD OVER THE REGION ON MONDAY WHICH SHOULD PRODUCE A VERY NICE DAY. SUNDAY AND MONDAY LOOK TO BE MILD WITH TEMPS ONE TO TWO CATEGORIES ABOVE NORMAL. THINGS GET MURKY RATHER QUICKLY AFTER MONDAY AS THE MEDIUM RANGE GUIDANCE CONTINUES TO BE IN FLUX. THE ECWMF AND GFS SOLUTIONS ARE QUITE DIFFERENT FOR CHRISTMAS ONWARD. AFTER CONSULTATION WITH NEIGHBORING OFFICES...IT WAS DETERMINED THAT HPC GUIDANCE WOULD BE UTILIZED WHICH LEANS HEAVILY ON THE ECWMF SOLUTION. THIS SOLUTION BRINGS A SHORT WAVE ACROSS THE AREA ON TUE WITH CYCLOGNESIS ALONG THE COAST. THIS WOULD SPARE THE SOUTHERN APPALACHIANS FROM MUCH IN THE WAY OF SIGNIFICANT PRECIP. MAYBE JUST SOME WIDELY SCATTERED/SCATTERED SHOWERS (POSSIBLY MIXED WITH SNOW AT HIGHER ELEVATIONS IN MOUNTAINS). THEN A DRY DAY WEDNESDAY. THE BEST THREAT FOR PRECIP THEN BECOMES THURSDAY AS A COLD FRONT APPROACHES FROM THE W. GFS ON THE OTHER HAND DEVELOPS A SWATH OF OVERRUNNUNG PRECIP OVER THE FORECAST AREA BY LATE TUE USING THE OLD BOUNDARY TO THE S. IT KEEPS THIS SWATH OF MOISTURE/PRECIP ACROSS THE REGION INTO THU ALONG THE STATIONARY FRONT...WITH A SOUTHERN STREAM LOW THEN EJECTING NE DURING THU TO THE W OF APPALACHIANS. HOPEFULLY WE WILL GET BETTER AGREEMENT AS WE DRAW CLOSER. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... CONDITIONS WERE SLOW TO DETERIORATE...BUT DETERIORATION IS NOW ONGOING...ESP OVER WRN SECTIONS. THERMAL ADVECTION AND LIFT...PLUS A LITTLE HELP FROM WEAK UPSLOPE WIND COMPONENT...WILL KEEP RAIN ACROSS THE AREA OVERNIGHT. THIS LIFT COMBINED WITH THE STRENGTHENING DAMMING HIGH WILL ALLOW IFR CONDITIONS TO DEVELOP BETWEEN 08Z AND 10Z. SFC LOW MOVES TO OUR EAST TODAY...TAKING BEST LIFT WITH IT. HOWEVER...LOW LEVEL MOISTURE AND WEAK ISENTROPIC LIFT CONTINUE THROUGH THE DAY...SO MVFR CIGS SHOULD REMAIN EVEN AFTER PRECIPITATION ENDS LATE THIS MORNING. THE MOISTURE AND LIFT CONTINUE TONIGHT...SO AT LEAST MVFR CIGS AND VSBY EXPECTED. CANNOT RULE OUT IFR...BUT THAT MAY HOLD OFF UNTIL CLOSER TO SAT MORNING. AVIATION OUTLOOK...CIG AND VSBY RESTRICTIONS ARE EXPECTED THROUGH SUNDAY AS MOISTURE LINGERS IN THE PERSISTENT COLD AIR DAMMING REGION. A COLD FRONTAL PASSAGE SHOULD SCOUR THE COLD WEDGE BY MON WITH COOL HIGH PRESSURE BUILDING IN BEHIND IT. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...BSH NEAR TERM...LGL SHORT TERM...LG LONG TERM...LG AVIATION...RWH sc AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD ..UPDATED AVN DISCUSSION 1157 AM CDT FRI DEC 21 2007 .DISCUSSION... UPDATED THE GRIDS AND ZFP. MAIN CONCERN WAS OVR THE ERN AND WRN SECTIONS OF THE FSD FA FOR THIS AFTERNOON. FIRST FOR OUR WEST...12Z RAOBS CAME IN AND SHOW A HUGE WARM LYR ABOVE THE SFC AT KABR AND KLBF. THIS WAS PICKED UP BY THE NAM/RUC MODEL SNDGS SO DECIDED TO CHANGE THE PCPN TYPE TO PURE RAIN GIVEN CURRENT SFC TEMP READINGS. EXCEPT FOR A POSSIBILITY MIX OF -RA/-FZRA IN KINGSBURY AND BROOKINGS COUNTIES FOR LATER THIS AFTERNOON WHERE SFC TEMPS ARE A BIT COOLER. ALSO BROUGHT IN A MIX OF -RA/-FZRA IN THE LATE AFTERNOON HRS TOWARD EVENING IN THE HURON AND CHAMBERLAIN VICINITIES AS SFC TEMPS COOL JUST BEHIND THE FROPA. HOWEVER FOR THE BULK OF THE AFTERNOON...WITH THEIR RISING DEWPT TEMPS...THEY SHOULD JUST GO OVER TO PURE RAIN IN OUR FAR WEST. IN OUR FAR EAST...DECIDED TO JUST GO AREAS OF FOG ALL AFTERNOON. THE WALL OF STRATUS CONTINUES TO HUG RIGHT ALONG THE CWA BORDER BETWEEN US AND DMX. BUT THERE ARE INDICATIONS ON SATELLITE THAT THIS SHOULD BEGIN TO BACK INTO OUR FA AS THE AFTERNOON PROGRESSES...AND ALSO THE H925 WINDS SHIFT FM THE S TO THE SE. AM HOPEFUL THOUGH...THAT THERE WILL BE ENUF THICKER HIGH CLOUDS OVR THE STRATUS TO KEEP DENSE FOG FM FORMING FM THE WINDOM MN TO STORM LAKE IA STRETCH. TONIGHT MAY BE A DIFFERENT STORY THOUGH...RIGHT AHEAD OF THE FROPA WHEN THE SFC WINDS GO DEAD. WL RE EVALUATE THAT A BIT LATER. && .AVIATION... LOW CIGS AND VIS ABOUND FOR THE TAF SITES THRU THE NEXT 24 HRS. FIRST FOR KSUX...THE LOW LEVEL WINDS WILL BACK TO AN ESE DIRECTION AS THE AFTERNOON PROGRESSES...LASTING INTO THIS EVENING. THEREFORE AM CONCERNED THAT THE LOW STRATUS AND FOG CURRENTLY TO THE E OF THIS AREA WILL BACK IN TOWARD EVENING...INTO THE IFR AND LIFR RANGE. WL HAVE TO MONITOR TO SEE IF THE FOG GOES 1/4SM DURING THE EVENING HRS BEFORE THE FROPA. AFTER THE FROPA...VIS WL GO UP...BUT WL STILL BE REDUCED IN ANY AREAS OF SN/BLSN WITH LOW CIGS STAYING PUT THRU SAT MORNING. SAME PROBLEM AT KFSD...WITH SOME POSSIBLE IFR CIGS BACKING IN FM THE EAST THIS EVENING. SNOW SHOWERS AFT MIDNIGHT WITH TEMPO IFR CIGS/VIS WARRANTED. AT KHON...NOT EXPECTING THE LOW VIS/CIGS TO THE EAST TO BACK INTO THIS AREA. BUT KHON WL LIKELY SEE MVFR/IFR CIGS/VIS AFTER THE FROPA IN SNOW/BLSN. && .PREV DISCUSSION... NEXT PBLM IS TIMIMG OF FNT. MODELS NOW SLOWER AND REALLY DO NOT PUSH FNT INTO WRN CWA UNTIL AFTN. S/W WAVE IN NRN FLOW WL SKIM BY THE NRN CWA THIS AFTN AND WL KEEP CHC OF S THERE WITH REST OF CWA DRY TODAY. FOCUS SHIFTS TO THE S WITH SRN STREAM WAVE FOR TONIGHT. BULK OF PRECIP TONIGHT WL OCCUR BEHIND FNT AND CLOSER TO SRN STREAM WAVE. AM CONCERNED THAT BULK OF PRECIP WL REMAIN. HAVE TRIMMED BACK POPS TO LIKELY OVR NW IA LATER TONIGHT AS FEEL PRECIP WL LIKELY HOLD OFF THERE UNTIL AAFTER 06Z WHEN SRN STREAM WAVE PUSHES ENE. AHEAD OF FNT TONIGHT...WL LIKELY SEE AREAS OF OFG ALONG WITH PATCHY DRIZZLE OR FREEZING DRIZZLE IN THE EVE SO PUT THAT IN FCST ACRS NW IA. ACRS REST OF CWA TONIGHT...WL SEE A CHC OF LIGHT SNOW WITH NRN TROF AND WNDS SHUD PICK UP BEHIND FNT AS CAA KICKS IN. WL BE CLOSE TO WND ADVY WRN CWA BUT FOR NOW WL NOT ISSUE HEADLINE. SAT LOOKS WINDY AND COLD WITH TEMPS NOT CLIMBING MUCH AT ALL. WUD EXPECT PLENTY OF STRATUS ERN CWA DURING THE DAY WITH CHC OF S- ACRS ERN CWA IN THE MORN. SUN LOOKS WINDS OND COLD AS UPPER LOW SITS OVR MN. EXPECT PLENTY OF SC OVR ERN CWA WITH A PSBLTY OF FLURRIES OVR SW MN. MOST PLACES WILL NOT GET OUT OF TEENS FOR HIGHS. HOLIDAY LOOKS DRY WITH NO MAJOR STORMS THRU NEXT WEEK. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ MJF sd AREA FORECAST DISCUSSION...AMENDED FOR WIND ADVISORY NATIONAL WEATHER SERVICE EL PASO TX/SANTA TERESA NM 213 PM MST FRI DEC 21 2007 .SYNOPSIS... A STRONG UPPER LEVEL TROUGH WILL CONTINUE TO SUPPLY THE BORDERLAND WITH BREEZY TO WINDY WESTERLY WINDS INTO THE OVERNIGHT HOURS TONIGHT...ESPECIALLY ALONG EAST-FACING SLOPES. IN ADDITION...THIS SYSTEM BRINGS WITH IT A GOOD SHOT FOR SIGNIFICANT SNOWFALL ACROSS THE MOUNTAINS OF SOUTHERN NEW MEXICO...BUT ONLY A SLIGHT CHANCE FOR PRECIPITATION NEARER THE INTERNATIONAL BORDER. MUCH COOLER TEMPERATURES CAN BE EXPECTED TOMORROW...AND OUR READINGS WILL HAVE A TOUGH TIME RECOVERING TO NORMAL LEVELS THROUGH THE REMAINDER OF THE WEEK. && .DISCUSSION... AS A STRONG BERING STRAIGHTS 500MB CYCLONE CONTINUES TO EJECT ENERGY INTO THE JET...EACH BURST STRENGTHENS AND PULLS SOUTH- SOUTHEAST AS THEY ENTER THE PACIFIC NW. MORE SPECIFICALLY...4 SUCH SYSTEMS WILL SKIRT THE CWA THROUGH THE 7-DAY PERIOD. THE FIRST TROUGH...ALREADY STRETCHING THROUGH UTAH AND ARIZONA AS OF 18Z TODAY...LOOKS TO BE OUR BEST SHOT FOR PRECIPITATION OF ANY OF THESE SYSTEMS. RUC-ANALYZED NEGATIVE LI`S JUST AHEAD OF THE 500 MB TROUGH AXIS HAVE BEEN HOST TO AN AREA OF CONVECTION ALL MORNING...AND HAVE PUSHED INTO WESTERN NEW MEXICO AS OF 20Z THIS AFTERNOON. THIS ACTIVITY WILL BE MAINLY RAIN EXCEPT ABOVE AROUND 7500 FEET AS IT MOVES INTO THE GILA ZONE THIS AFTERNOON. SNOW LEVELS WILL DROP QUICKLY TO BELOW 5000 FEET NORTH OF LAS CRUCES BY MIDNIGHT TONIGHT AS COLD AIR FILTERS IN FROM THE NORTH AT THE SURFACE BEHIND A SIDE-DOOR FRONT. BY THIS TIME OUR MAIN TROUGH AXIS WILL HAVE PUSHED FAR ENOUGH EAST TO LIMIT THE RISK FOR SIGNIFICANT SNOWS IN THE LOWLANDS. WITH THE MAIN BAND OF ENERGY HOLDING OFF UNTIL LATER TO EFFECT THE SACRAMENTO MOUNTAIN AREA...MORE SIGNIFICANT SNOWS LOOK TO BE MORE LIKELY THERE. AMOUNTS APPEAR TO BE WELL-HANDLED WITH THE CURRENT ADVISORIES. A STRONG SURFACE PRESSURE GRADIENT WILL REMAIN ESTABLISHED OVERNIGHT TONIGHT AS A STRENGTHENING LEE-SIDE LOW SLIDES ACROSS NORTHERN TX. THIS WILL SUPPORT BREEZY TO WINDY CONDITIONS - ESPECIALLY ACROSS THE EAST-SLOPES OF AREA MOUNTAINS - THROUGH THE NIGHT. MUCH COOLER TEMPERATURES FOR TOMORROW WILL BE HARD TO BRING UP AS DISTURBANCE AFTER DISTURBANCE CROSSES THE AREA BRINGING WITH THEM REINFORCING SHOTS OR COOL AIR. OUR SECOND DISTURBANCE...SLATED FOR SUNDAY NIGHT/MONDAY CONTINUES TO LOOK DRIER. AS SUCH...HAVE REMOVED MENTIONABLE POPS FOR THE SYSTEM. THE THIRD DISTURBANCE IS SLATED FOR CHRISTMAS DAY. AS READINGS FINALLY RETURN TO LATE-DECEMBER NORMS...A STRONG UPPER LEVEL TROUGH IS PROGGED TO DIG INTO THE SOUTHWEST. CURRENT MODEL SOLUTIONS INDICATE WINDY CONDITIONS WITH THE POTENTIAL FOR MAINLY THE NORTHERN PORTIONS OF THE CWA TO SEE AND PRECIPITATION. THIS WOULD BE FOLLOWED AGAIN BY A COLD AIR INTRUSION FROM THE NORTH FOR THE 26TH. OUR FOURTH AND FINAL DISTURBANCE OF THE PERIOD LOOKS MUCH LIKE THE 3RD...AND WOULD MAKE FOR BREEZY TO WINDY CONDITIONS AND A SLIGHT CHANCE OF PRECIPITATION MAINLY NORTH OF LAS CRUSES THURSDAY AFTERNOON/EVENING. && .AVIATION...VALID 22/00Z-23/00Z MOSTLY VFR CONDITIONS EXPECTED THROUGH THE PERIOD. HOWEVER...THERE WILL BE AREAS OF MVFR AND IFR TONIGHT INTO SATURDAY MORNING FOR CIGS AND VSBY IN RAIN/SNOW SHOWERS THAT WILL OBSCURE MTN TOPS. WINDS OF 20 TO 25 KTS GUSTING TO 35 KTS THIS EVENING INTO TONIGHT WILL LIKELY CAUSE MODERATE MECHANICAL TURBULENCE...ESPECIALLY ACROSS EASTERN SLOPES OF AREA MOUNTAINS. WINDS DIMINISHING DURING THE NIGHT AND VFR CONDITIONS RETURNING FROM WEST TO EAST SATURDAY MORNING. && .PRELIMINARY POINT TEMPS/POPS... EL PASO 36 50 25 53 30 / 10 0 0 0 0 SIERRA BLANCA TX 35 48 23 53 26 / 10 0 0 0 0 LAS CRUCES 33 50 24 52 29 / 10 0 0 0 0 ALAMOGORDO 32 50 21 50 25 / 20 10 0 0 0 CLOUDCROFT 25 33 10 37 16 / 60 20 0 0 0 TRUTH OR CONSEQUENCES 31 47 21 50 26 / 20 0 0 0 0 SILVER CITY 28 43 19 45 22 / 30 0 0 0 0 DEMING 32 49 22 51 28 / 10 0 0 0 0 LORDSBURG 31 49 21 51 27 / 20 0 0 0 0 && .EPZ WATCHES/WARNINGS/ADVISORIES... NM...WIND ADVISORY UNTIL 6 PM MST THIS AFTERNOON FOR NMZ022>025- 030>032. SNOW ADVISORY UNTIL 6 AM MST SATURDAY FOR NMZ022. SNOW ADVISORY FROM 6 PM THIS EVENING TO 12 PM MST SATURDAY FOR NMZ025. TX...WIND ADVISORY UNTIL 6 PM MST THIS AFTERNOON FOR TXZ055-056. && $$ PIEPER tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 826 PM CST THU DEC 20 2007 .UPDATE...THE NAM/GFS DETERMINISTIC SOLNS PROGD 00Z FRI SFC DEW POINTS 5-10C DEGRESS GREATER THAN METAR VALUES. THE LOCAL MM5 PROGD THE LOWEST 00Z FRI SFC DEW POINTS OVR THE NERN CWFA... INCONSISTENT WITH THE 00Z FRI OBSERVATIONS. YET...THE RUC SOLN PERFORMED MUCH BETTER IN THIS RESPECT...AND THUS MORE CONFIDENT IN THIS SOLN. HWR...ALTHOUGH THE RUC PROGS 12Z FRI SFC TEMPS HIGHER THAN THE CURRENT FCST...WL DEFER TO THE CURRENT FCST. ANTICIPATE THAT LIGHT WIND/EXTREMELY DRY CONDITIONS/DECOUPLING CONDITIONS WL ALLOW FOR SFC TEMPS TO MOVE CLOSER TO THE SFC DEW POINTS. THUS... WL RETAIN THE CURRENT TEMP FCST. CAVEAT...THE NAM/GFS PROG WEAK ONSHORE WIND AFT 09Z FRI...WHICH COULD RESULT IN HIGHER MIN TEMPS OVR THE COASTAL COUNTIES. && .AVIATION...VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 83 45 80 63 77 / 0 0 0 10 10 VICTORIA 81 43 78 58 72 / 0 0 0 20 20 LAREDO 82 45 84 56 75 / 0 0 0 0 10 ALICE 84 43 83 59 77 / 0 0 0 10 10 ROCKPORT 82 49 76 63 75 / 0 0 0 20 20 COTULLA 81 41 81 53 72 / 0 0 0 0 10 KINGSVILLE 84 43 82 61 79 / 0 0 0 10 10 NAVY CORPUS 82 50 78 65 76 / 0 0 0 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ WC/87...SHORT TERM JR/19...AVIATION tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREEN BAY WI 841 PM CST FRI DEC 21 2007 .UPDATE...FG NOT EXCEPTIONALLY DENSE ACRS THE AREA...BUT JUST DON/T SEE HOW CONDITIONS ARE GOING TO IMPROVE WITH ABV FZG DWPTS CONTINUING TO ADVECT OVER THE SNOWCOVER DURING THE NGT. THE RUC13 SFC VSBY GRIDS IN AWIPS SEEMED TO HAVE A DECENT HANDLE ON THE SITN. THE PAST TWO RUNS BOTH PROGGED THE < 1/4 MI VSBYS TO EXPAND DURING THE NGT...AND TO COVER ALMOST ALL OF THE AREA BY 12Z. WL EXPAND THE DENSE FOG ADVISORY TO COVER ALL BUT DOOR COUNTY. THE DOOR IS PROBABLY SEEING SLIGHTLY DRIER AIR WORKING IN FM THE E. WL NOT BE MAKING ANY CHANGES TO THE WINTER STORM WATCH ON THIS SHIFT. THE KEY FACTOR WL OBVIOUSLY BE THE TIMING OF THE CHANGEOVER TO SNOW. SEEMS THAT IN MOST CASES THE MODELS SEEM TO BRING THE CHANGE EWD TOO QUICKLY. BUT THEN AGAIN THERE ARE THE HANDFUL OF CASES WHERE THE DYNAMICS ARE SO STG THAT THE INTENSE LIFT COOLS THE COLUMN AND RESULTS IN A MORE RAPID CHG TO SNOW. AS EXPECTED...THE NEW NGM AND NAM BOTH KEPT THE SRN STREAM UPR SYSTEM STRONGER AND MAINTAINED IT/S IDENTITY LONGER. THEY ALSO SLOWED IT A BIT...AND BROUGHT VERY STG LIFT THROUGH E-C WI LATE SAT NGT. IT/S GOING TO BE REAL TOUGH GETTING A HANDLE ON THE CHANGEOVER TIME FOR E-C WI UNTIL WE ACTUALLY GET INTO THE EVENT. NO GLARING PROBLEMS WITH THE HANDLING OF THE EVENT IN THE CURRENT FCST...SO WON/T BE MAKING ANY CHANGES. UPDATED PRODUCT SUITE WL BE OUT ASAP. SKOWRONSKI && .PREV DISCUSSION...ISSUED AT 354 PM CST FRI DEC 21 2007... SHORT TERM...TONIGHT THROUGH SATURDAY. MELTING SNOW AND LIGHT WINDS WILL RESULT IN DENSE FOG TONIGHT. ISSUED AN ADVISORY FOR MOST OF THE FORECAST AREA THROUGH 9 O`CLOCK SATURDAY. LOTS OF LOW LEVEL MOISTURE AROUND TONIGHT FOR FOG BUT NOT MUCH FOR ANY PRECIPITATION OTHER THAN PATCHY DRIZZLE OR FREEZING DRIZZLE UNTIL TOMORROW. NOT MUCH FALL IN TEMPERATURES EXPECTED TONIGHT AND ONLY A FEW DEGREE RISE TOMORROW. LONG TERM...SAT NGT THRU NXT FRI. MAIN FCST CHALLENGE REMAINS HANDLING OF INTENSIFYING STORM LATE THIS WEEKEND AND SNOW AMTS ASSOCIATED WITH IT. FOR LTR PERIODS...A SERIES OF PAC STORMS ARE EXPECTED TO HIT THE WEST COAST NXT WEEK...WITH THE MORE ACTIVE SRN BRANCH TAKING MOST OF THE PCPN SOUTH OF NE WI. NRN FRINGE OF ONE OF THESE STORMS MAY GRAZE THE AREA WED NGT INTO THU...WITH ANOTHER FOR LATE FRI. NO ARCTIC AIR IN SIGHT...THUS TEMPS WL REMAIN AT OR ABV NORMAL FOR LATE DEC. SFC BNDRY TO MOV ACROSS THE FCST AREA SAT EVENING TURNING THE WNDS TO THE WEST AND USHER IN COLDER AIR TO THE RGN. PHASING STORM STILL PROGGED TO CONSOLIDATE A SFC LOW OVR NRN SECTIONS OF LK MI BY 12Z SUNDAY. PLENTY OF GULF MSTR WL BE AVBL AS THE STORM DVLPS WITH THE MAIN KEY TO THE SNOW AMTS BEING THE TIMING OF RAIN OVER TO SNOW TRANSITION. GOOD DYNAMICS INVOLVED (STG Q-VEC CONVERGENCE/ FRONTOGENETICAL SIGNAL) AND STG UVV ALL POINT TO A GOOD QPF EVENT. AFTER COLLARBORATING WITH SURROUNDING OFFICES...FEEL MAINTAINING A WINTER STORM WATCH IS PRUDENT ESP SINCE PHASING SYSTEMS OFTEN DO NOT COME OFF EXACTLY AS PLANNED. HAVE EXPANDED THE WATCH A TIER OF COUNTIES EAST (TO INCLUDE FLORENCE/MENOMINEE/SHAWANO/WAUPACA) AS POTENTIAL FOR 4+" IS PSBL. HAVE ALSO SEPARATED THE WATCH INTO TWO SECTIONS WITH CNTRL WI RUNNING FROM 00Z SUN-18Z SUN (NO CHG) AND NRN WI FROM 00Z SUN-00Z MON. CURRENT THINKING IS THAT ERN WI WL NOT SEE A CHANGEOVER TO ALL SNOW TIL LATE SAT NGT WHICH WOULD OBVIOUSLY IMPACT SNOW AMTS. HEAVIEST SNOWS SHOULD RUN FROM CNTRL TO NRN WI WHERE AN INITIAL 3 TO 6 INCHES OF ACCUMULATION IS LIKELY TO FALL BY DAYBREAK (BULK COMING AFT MIDNGT). LASTLY...INTENSIFYING STORM WL TIGHTEN THE PRES GRAD TREMENDOUSLY TOWARD DAYBREAK. EVEN THO THE SNOW SHOULD BE OF A WET VARIETY TO BEGIN WITH...CAN SEE SOME BLOWING AND DRIFTING OCCURRING TOWARD DAYBREAK. SFC LOW MOVS ALMOST DUE NORTH INTO EITHER ERN LK SUPERIOR OR EXTREME S-CNTRLL ONTARIO ON SUNDAY AS THE 5H UPR LOW ROTATES THRU THE GREAT LKS. THE BRUNT OF THE DYNAMICS SHIFTS NORTH AND EAST DURING THE DAY SUCH THAT MOST OF THE SNOW ACROSS CNTRL/E-CNTRL WI WOULD START TO DIMINISH BY MIDDAY. NRN WI HOWEVER WL SEE THE SNOW PERSIST THRU THE AFTERNOON WITH STG CYCLONIC FLOW AND WRAP-AROUND MSTR ROTATING THRU. THIS IS THE REASON THE WATCH WAS EXTENDED TO 00Z MON FOR NRN WI. IN ADDITION TO THE SNOW...A VERY WINDY DAY ON TAP WITH MOST LOCATIONS SEEING STEADY 20 TO 30 MPH WNDS AND GUSTS UP TO 45 MPH PSBL. AS FOR TEMPS...PERSISTENT CAA WL HAVE READINGS EITHER STEADY OR SLOWLY FALLING THRU THE DAY. THE STORM MOVES NE INTO QUEBEC SUNDAY NGT WITH THE PRES GRAD SLOWLY RELAXING (STILL 10 TO 20 MPH AT 12Z MON). WE MAY STILL BE DEALING WITH SOME ROGUE WRAP-AROUND MSTR/SHRTWVS DURING THE NGT... THUS A CHC OF LGT SNOW OR FLURRIES APRS THE WAY TO GO. CYCLONIC FLOW EXPECTED TO LOSE ITS INFLUENCE ON NE WI ON MON AS THE STORM CNOTS TO PULL AWAY AND HI PRES BUILDS INTO THE AREA. ANY LINGERING THREAT OF LK EFFECT SNOW SHWRS OR FLURRIES OVR FAR NRN WI WL COME TO AN END AS WNDS BEGIN TO BACK AND DRIER AIR STARTS TO ADVECT IN. SOME AFTERNOON SUNSHINE SHOULD ALLOW TEMPS TO REACH THE 20`S THROUGHOUT NE WI AND MAY ADD A DEG OR TWO TO THE PREV FCST. HI PRES AT THE SFC WL COMBINE WITH A SHRTWV RDG ALOFT TO THEN SETTLE OVR THE GREAT LKS FOR XMAS DAY. QUIET CONDITIONS TO PREVAIL AND AS WNDS BACK MORE SW TUE AFTERNOON...TEMPS SHOULD BE ABLE TO WARM A BIT. HAVE RAISED MAX TEMPS A FEW DEGS AS A RESULT. THIS HI PRES SHIFTS TO OUR EAST BY THE MIDDLE OF NXT WEEK ALLOWING FOR A WEAK NRN STREAM SHRTWV TROF/ASSOCIATED CDFNT TO ENTER THE WRN GREAT LKS. A MORE ACTIVE/STRONGER SRN STREAM STORM TO BE ORGANIZING OVR THE DEEP SOUTH ON WED...BUT APRS TO BE TOO FAR SOUTH FOR ANY OF ITS PCPN TO AFFECT NE WI. INSTEAD...WE WL ONLY HAVE A MINIMAL CHC OF LGT SNOW AS THE CDFNT APPROACHES. THE SRN STREAM STORM GETS BOOTED NEWD INTO THE MIDWEST WED NGT AND INTO THE ERN GREAT LKS ON THU AS AN UPSTREAM KICKER MOVS INTO THE DESERT SW. SFC LOW TO TRACK ROUGHLY FROM SE IL TO SE LWR MI ON THU WHICH WOULD KEEP HEAVIER SNOW TO OUR SOUTH AND EAST. PREFER TO KEEP CHC POPS FOR LGT SNOW GOING FOR NOW. AS THIS SYSTEM PULLS OUT THU NGT...WL BE WATCHING THE NXT SRN STREAM STORM GETTING ITS ACT TOGETHER OVR THE SRN PLAINS. WAY TOO EARLY TO TELL THE EVENTUAL TRACK OF THIS STORM ALTHO THE ECMWF AND GFS ARE TRENDING THE BULK OF THE STORM`S IMPACT WOULD AGAIN BE TO OUR SOUTH AND EAST. HAVE PLACED CHC POPS IN THE FCST FOR FRI AS A STARTING POINT. AVIATION...LOW IFR WEATHER EXPECTED JUST ABOUT EVERYWHERE TONIGHT AND EARLY SATURDAY. MARINE...SCA ISSUED SATURDAY AFTEROON THROUGH SUNDAY. GALE WARNINGS POSSIBLE SUNDAY. && .GRB WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 9 AM SATURDAY WIZ005-010>013-018>021-030-031-035>040-045-048>050-073-074- WINTER STORM WATCH SATURDAY EVENING THROUGH SUNDAY AFTERNOON WIZ005-010>012-018-019- WINTER STORM WATCH SATURDAY EVENING THROUGH SUNDAY MORNING WIZ020-030-031-035>037-045- && $$ wi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LA CROSSE WI 927 PM CST THU DEC 20 2007 .UPDATE... LATEST RUC SOUNDINGS INDICATE LOW LEVEL MOISTURE DEPTH TO DECREASE FROM WEST TO EAST TONIGHT ACROSS THE AREA. SO GREATEST THREAT FOR FZDZ LOOKS TO REMAIN TO THE EAST OF THE MISSISSIPPI RIVER. RADAR RETURNS OVER THE PAST HOUR HAVE BEEN DIMINISHING ACROSS THE EASTERN COUNTIES...BUT CALLS STILL INDICATE VERY LIGHT RAIN/DRIZZLE/FREEZING DRIZZLE STILL OCCURRING WITH MOST OF THE SUB-FREEZING TEMPERATURES FOUND NORTH OF HIGHWAY 29. VISIBILITIES HAVE HELD UP IN THE ONE HALF TO ONE MILE RANGE ACROSS THE NORTHERN HALF OF THE DENSE FOG ADVISORY AREA FOR MOST OF THE EVENING. BUT ACROSS NORTHEAST IOWA ONE QUARTER OR LESS IS BEING REPORTED. WITH CONTINUED SOUTHEAST FLOW STILL EXPECT WIDESPREAD DENSE FOG ACROSS THE WESTERN ZONES OVERNIGHT AND INTO FRIDAY MORNING. ALL IN ALL GRIDS LOOKS TO BE IN GOOD SHAPE AND PLAN NO MAJOR CHANGES TO ONGOING FORECAST. && JLR .PREV DISCUSSION... .SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT FORECAST CONCERNS THIS PACKAGE...DENSE FOG/DZ/FZDZ TONIGHT... POTENTIAL WINTER STORM CENTERED ON SAT/SAT NIGHT. DATA ANALYSIS AT 18Z HAD ONE LOW PRESSURE CENTERED OVER ALB AND A WEAKER ONE OVER THE LA/AR AREA. BROAD SOUTH/SOUTHEAST FLOW AHEAD OF THESE LOWS WAS PUSHING WARM/MORE MOIST AIR NORTH INTO THE REGION. DEW POINTS INTO THE UPPER 20S/LOW 30S ACROSS MUCH OF IA/SOUTHERN WI/NORTHERN IL. FOG-PRODUCT/VIS IMAGERY/SFC OBS SHOWING LOW STRATUS DECK ADVECTING/EXPANDING NORTH ACROSS AREA ALONG AND EAST OF I-35. VSBYS ALREADY LESS THAN 2SM IN FOG OVER THE WEST HALF OF THE FORECAST AREA AS THE INCREASING MOIST AIRMASS IS ADVECTED NORTH OVER THE SNOW COVERED LANDSCAPE. EARLY AFTERNOON TEMPS IN THE LOW/MID 30S...ADDING TO THE BOUNDARY LAYER MOISTURE WITH SOME MELTING SNOW. NO MAJOR ERRORS NOTED WITH 20/12Z NAM/GFS INITIALIZATIONS...WITH SOLUTIONS MORE SIMILAR TO EACH OTHER THAN THEIR RUNS OF 12 AND 24HRS AGO. GFS TRENDING TOWARD THE STRONGER...MORE PHASED ECMWF/UKMET/NAM SOLUTIONS WITH THE TROUGH AS IT LIFTS THRU THE UPPER MIDWEST SAT/ SUN. NAM STILL THE STRONGEST...WITH GFS/ECMWF/UKMET OFFERING A RATHER GOOD CONSENSUS AT THE SFC/500MB AT 12Z SUN. DPROG/DT OF 500MB HGTS AT 20/12Z SHOWED NAM/GFS RUNS OF 18/12Z AND 19/12Z VERIFIED REASONABLY WELL ACROSS NOAM/EASTERN PAC. MODELS HAVE TRENDED TOWARD THE STRONGER LOOK OF NAM WITH THE ENERGY OFF THE CA COAST WHILE TRENDING TOWARD THE GFS WITH THE NORTHERN STREAM ENERGY OVER BC. THRU 36HRS...NAM SHOWS THE BETTER RUN-TO-RUN CONSISTENCY WIT THE SOUTHERN STREAM ENERGY INTO AZ/NM WHILE GFS SHOWS THE BETTER CONSISTENCY WITH THE NORTHERN STREAM ENERGY INTO MT/SASKAT. FOR 36- 84HRS MODELS HAVE CONVERGED ON A COMMON SOLUTION WITH THE SOUTHERN STREAM ENERGY LIFTING TO MO/AR WHILE CONSIDERABLE DIFFERENCE STILL REMAIN WITH THE NORTHERN STREAM/DEVELOPING UPPER LOW OVER THE NORTHERN PLAINS/WESTERN GREAT LAKES. TREND IS TOWARD ECMWF IN THIS TIME-FRAME...WITH 20/00Z ECMWF OFFERING A REASONABLE COMPROMISE OF LATEST NAM/GFS SOLUTIONS AT 60/72HRS AS NORTHERN/SOUTHERN STREAM PHASE. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED NAM/GFS REASONABLE WITH THE SFC MASS FIELDS ACROSS CENTRAL NOAM. PER WV IMAGERY... MODELS LOOK TO HAVE GOOD DEPICTIONS OF THE SHORTWAVE FEATURES OVER NOAM/EASTERN PAC...WITH A MODEL COMPROMISE PERHAPS A BIT BETTER THAN EITHER NAM/GFS ALONE. GOOD DARKENING SEEN IN WV IMAGERY WITH THE SHORTWAVE COMING ON THE CA COAST. WITH ALL THE MODEL VARIABILITY OF LATE AND 18Z DATA TENDING TO SUPPORT A MODEL COMPROMISE...PREFER THAT SOLUTION THIS CYCLE. GIVEN DEPENDENCE OF FORECAST ON NUANCES OF NORTHERN/SOUTHERN STREAM PHASING...SHORT-TERM FORECAST CONFIDENCE AVERAGE AT BEST. FOR THE SHORT TERM...SOUTH/SOUTHEAST WINDS TONIGHT WILL CONTINUE TO ADVECT MOISTURE NORTHWARD ACROSS THE AREA...OVER THE SNOW PACK AND UNDER AN INVERSION NEAR 850MB. WITH VSBYS ALREADY LOW AND THE CONTINUED LOADING OF THE SUB-INVERSION LAYER WITH MOISTURE...WILL ISSUE A DENSE FOG ADVISORY FOR TONIGHT INTO FRI MORNING FOR AREAS WEST OF THE MS RIVER. LOW CLOUD/FOG BLANKET AND CONTINUED LOW LEVEL WARM ADVECTION...TEMPS TO BE NEARLY STEADY TONIGHT NEAR THE FREEZING MARK. WITH WEAK CONVERGENCE/LIFT IN THE MOIST SFC-850MB LAYER...PATCHY DZ/FZDZ STILL LOOKS REASONABLE TONIGHT. AS DEPTH OF MOISTURE DECREASES FROM WEST TO EAST LATER TONIGHT...THREAT OF DZ/FZDZ WILL DIMINISH AS WELL...AND THIS ALREADY DEPICTED IN GRIDS. WITH CONTINUED MOIST SOUTH WINDS OVER THE SNOW COVER FRI...FOG WILL PERSIST THRU MUCH OF THE DAY AND ADVISORY MAY NEED TO BE EXTENDED INTO THE EARLY AFTERNOON...MUCH LIKE WED. ATTENTION QUICKLY TURNS TO WEEKEND SYSTEM AND POTENTIAL FOR SIGNIFICANT SNOW FOLLOWED BY STRONG WEST/NORTHWEST WINDS. LATEST MODEL SUITE/ENSEMBLES HAVE TRENDED STRONGER/MORE PHASED WITH THE NORTHERN/SOUTHERN STREAMS AS THE SHORTWAVES CROSS THE MID MS VALLEY AND UPPER MIDWEST. THIS MORE PHASED SOLUTION BRINGS DEEPER MOISTURE /4-5 G/KG/ AND DEEPER/STRONGER 850-500MB FN/QG CONVERGENCE NORTHWARD INTO THE FORECAST AREA CENTERED ON 00Z SUN. THIS COUPLED WITH STRONGER PV ADVECTION AND 300MB AGEOSTROPHIC FLOW/DIVERGENCE ALOFT. SOUNDINGS INITIALLY SUPPORT PRECIP AS SNOW OVER THE NORTHWEST HALF OF THE FORECAST AREA SAT MORNING...TO RAIN OVER THE SOUTHEAST END. APPEARS TO BE ONLY SMALL CHANCES OF MIXED/FREEZING PRECIP TYPES WITH THIS SYSTEM AS SOUNDINGS SHOW AIRMASS WARMER THAN 0C MIXED TO THE SFC. DEEP DYNAMIC LIFT/COOLING OF THE AIRMASS AHEAD OF THE EJECTING SOUTHERN STREAM SHORTWAVE THEN LOOKS TO QUICKLY COOL THE COLUMN FROM THE TOP DOWN AND CHANGE AND RA/SN MIX TO ALL SNOW LATE SAT MORNING/AFTN. GIVEN VERY DYNAMIC TREND OF THIS SYSTEM /SFC LOW DEEPENS ABOUT 14MB FROM 00Z SUN TO 12Z SUN/...THE TREND TOWARD A STRONGER MORE PHASED SOLUTION...AND POTENTIAL IMPACT ON A MAJOR HOLIDAY TRAVEL WEEKEND...ISSUED A WINTER STORM WATCH FOR THE SOUTHERN THIRD OF THE FORECAST AREA FOR SAT AFTERNOON/NIGHT AS A START. AS DETAILS BECOME CLEARER...POTENTIAL FOR THE WATCH TO BE EXPANDED NORTH/EAST WITH LATER ISSUANCES. WITH THE RAPIDLY DEEPENING LOW SAT NIGHT PRESSURE GRADIENT OVER THE AREA INCREASES BY 12Z SUN WITH STRONG/GUSTY WEST/NORTHWEST WINDS IN THE WAKE OF THE LOW FOR LATE SAT NIGHT/MUCH OF SUNDAY. MAY NEED TO EXPEND WATCH OR ANY LATER HEADLINES INTO SUNDAY DUE TO STRONG WINDS CREATING BLOWING/DRIFTING SNOW. WITH A BETTER CONSENSUS FOR THE STRONGER SYSTEM...RAISED POPS FOR MUCH THE SAT/SAT NIGHT PERIOD INTO LIKELY/CATEGORICAL RANGES. POTENTIAL FOR WRAP-AROUND DEFORMATION BAND OF -SN TO REMAIN OVER THE AREA ON SUN AND RAISED -SN CHANCES ON SUN AS WELL. WITH CLOUD/FOG BLANKET...FAVORED WARMER OF GUIDANCE LOWS TONIGHT WITH NEAR STEADY TEMPS. WITH CLOUDS/FOG FRI...TRENDED TOWARD COOLER OF GUIDANCE HIGHS. FAVORED A BLEND OF GUIDANCE LOWS/HIGHS FRI NIGHT/SAT...WITH FALLING TEMPS DURING THE DAY SAT. TRENDED TOWARD COLDER OF GUIDANCE LOWS SAT NIGHT AS COLD AIR POURS IN AND THE UPPER LOW DROPS ACROSS THE REGION. PREFERRED A BLEND OF GFS MEX/ ENSEMBLE MOS AND HPC GUIDANCE FOR HIGHS/LOWS SUN/SUN NIGHT. .LONG TERM...MONDAY THROUGH THURSDAY 20/00Z MEDIUM RANGE MODELS/ENSEMBLE MEAN OFFER A MODEST CONSENSUS WITH EACH OTHER FOR MON-THU...BUT DIFFERENCES IN TIMING/STRENGTH OF THE SHORTWAVE TROUGHS INCREASES THRU THE PERIOD. RUN-TO-RUN CONSISTENCY OF TIMING/STRENGTH DETAILS BY TUE AND BEYOND IS QUITE LOW. THIS NOT UNEXPECTED GIVEN MODELS STILL STRUGGLING WITH THE NORTHERN/SOUTHERN STREAM BALANCE OF ENERGY WITH THE SYSTEM THIS WEEKEND AND NUMEROUS STRONGER SHORTWAVE TROUGHS ACROSS THE CONUS FOR NEXT WEEK. THUS...FORECAST CONFIDENCE IN THE LONG TERM ON THE LOW SIDE THIS CYCLE. GFS ENSEMBLE MEAN DOES TREND TOWARD A MODEL BLEND/ COMPROMISE OF THE GFS/ECMWF/UKMET RUNS...AT LEAST WITH TIMING OF FEATURES. WHAT MODEL CONSENSUS THERE IS INDICATES A RATHER ACTIVE FLOW PATTERN ACROSS NOAM THRU NEXT WEEK...ESPECIALLY THE SOUTHERN STREAM. UPPER MIDWEST LOOKS TO BE CAUGHT UNDER SPLIT FLOW MON/TUE WITH A COLD SFC HIGH PRESSURE RIDGE SLIDING ACROSS THE REGION...FOR DRY...QUIET WEATHER. FOR WED/THU ECMWF AND TO A LESSER DEGREE GFS ENSEMBLE MEAN TRENDING TOWARD SOME PHASING OF THE NORTHERN/SOUTHERN STREAMS AND A SIGNIFICANT TROUGH LIFTING NORTHEAST ACROSS THE CENTRAL CONUS. UKMET/CAN GEM/20/06Z GFS RUN LOOK TO MAINTAIN MORE OF A SPLIT FLOW AND BULK OF THE ACTIVE WEATHER SOUTH OF THE AREA. HPC TRENDED TOWARD A MODEL COMPROMISE WEIGHTED TOWARD THE USUALLY BETTER ECMWF AND ENSEMBLES FOR WED/THU. SMALL SNOW CHANCES WED INTO THU LOOKS REASONABLE FOR NOW GIVEN RANGE MODEL SOLUTIONS AND LOWER FORECAST CONFIDENCE BY DAYS 6/7 FOR ANY ONE PARTICULAR OUTCOME. FAVORED A BLEND OF GFS MEX/ENSEMBLE MOS AND HPC GUIDANCE MAXES/MINS THRU THE PERIOD. && .AVIATION...TONIGHT AND FRIDAY LOW CLOUDS AND/OR FOG EXPECTED TO PERSIST ACROSS THE AREA THROUGH TONIGHT AND INTO FRIDAY. THIS BASED ON EXPANSE OF STRATUS CONTINUING TO MOVE NORTHWARD FROM IOWA AND ILLINOIS. IN FACT...BASED ON CURRENT CONDITIONS AND LOCAL STUDY OF DENSE FOG EVENTS...FORECAST CONFIDENCE WAS HIGH FOR KRST TAF SITE TO HAVE VISIBILITY NEAR 1/4 MILE DURING LARGE PORTIONS OF 18Z 20DEC07 TAF VALID TIME. SOME IMPROVEMENT SHOULD OCCUR AFTER 16Z 21DEC07. LOOKING AHEAD...POTENTIAL FOR WINTRY PRECIPITATION EVENT TO IMPACT BOTH KRST AND KLSE TAF SITES AND IN FACT MOST OF THE AIRPORTS IN THE FORECAST AREA THIS WEEKEND. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH LATE SATURDAY NIGHT FOR WIZ053-WIZ054-WIZ055-WIZ061. MN...DENSE FOG ADVISORY UNTIL 10 AM CST FRIDAY FOR MNZ079-MNZ086- MNZ087-MNZ088-MNZ094-MNZ095-MNZ096. IA...DENSE FOG ADVISORY UNTIL 10 AM CST FRIDAY FOR IAZ008-IAZ009- IAZ010-IAZ011-IAZ018-IAZ019-IAZ029-IAZ030. WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH LATE SATURDAY NIGHT FOR IAZ008-IAZ009-IAZ010-IAZ011-IAZ018- IAZ019-IAZ029-IAZ030. && $$ SHORT/LONG TERM...RRS AVIATION..........THOMPSON wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 1026 AM CST THU DEC 20 2007 .UPDATE...PRIMARY CONCERN WAS WITH DENSE FOG ACROSS PARTS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA TODAY. SATELLITE IMAGERY INDICATED STRATUS EXPANDING STEADILY NORTHWARD INTO FORECAST AREA THIS MORNING. VISIBILITY LOWERS TO AS LOW AS 1/4 MILE PER 16Z OBSERVATION AT KOLZ. LATEST RUC AND 12Z 20DEC07 NAM/WRF SUPPORTED LOW CLOUDS AND FOG TO CONTINUE PUSHING NORTHWARD TODAY ACROSS THE ENTIRE FORECAST AREA. BASED ON CURRENT OBSERVATIONS...INCLUDED FOG ACROSS PARTS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA REST OF TODAY. WILL CONTINUE TO MONITOR VISIBILITY TRENDS IN CASE WIDESPREAD 1/4 MILE SCENARIO DEVELOPS. FOR NOW...HAVE UPDATED CURRENT DATA BASE AND WILL UPDATE ZONE FORECASTS FOR LATEST TRENDS. && THOMPSON .PREV DISCUSSION... /ISSUED 340 AM CST THU DEC 20 2007/ SHORT TERM...TODAY THROUGH SATURDAY NIGHT FORECAST FOCUS IN THE SHORT-TERM CENTERS ON THE PCPN CHANCES FOR TODAY...AND THEN WHAT THE WEEKEND SYSTEM WILL DO. TODAY...A RELATIVE WEAK AND PROGRESSIVE 500 MB SHORTWAVE TROUGH WILL TRACK EAST ACROSS THE REGION. DESPITE ITS NON-DESCRIPT APPEARANCE...THIS FEATURE WILL BRING SOME QG CONVERGENCE THROUGH THE LAYERS WITH IT...ALONG WITH SOME BROAD LOW LEVEL WARMING ON THE 925:700 MB SFCS. SOME ISENTROPIC UPGLIDE IS ALSO INDICATED AHEAD OF THE SHORTWAVE TROUGH...IN THE 285:300 K SFCS. THE THERMODYNAMIC LIFT PEAKS THIS AFTERNOON ALONG AND EAST OF THE MISSISSIPPI RIVER...GENERALLY EXITING EAST BETWEEN 00-06Z. SO...THERE IS SOME LIFT TO WORK WITH...AND POTENTIALLY SOME PCPN...ALL DEPENDING ON HOW MUCH SATURATION THERE WILL BE. A WEST-EAST RUNNING X-SECTION HAS THE CURRENT HIGH/MID LEVEL SATURATION PUSHING EAST BY THIS AFTERNOON...WITH AN INCREASE IN THE LOW LEVEL MOISTURE //800MB TO THE SFC// THIS AFTERNOON. THE MOISTURE ISN/T DEEP ENOUGH TO SUPPORT ANY SIGNIFICANT PCPN PROCESSES...BUT IT IS FOR DRIZZLE/FREEZING DRIZZLE. SO...WITH SOME BROADSCALE LIFT THROUGH THE TOP OF THIS LAYER...PATCHY DRIZZLE/FREEZING DRIZZLE WILL BE POSSIBLE...MOSTLY THIS AFTERNOON AND EARLY EVENING...AND MOSTLY ALONG AND EAST OF THE MISSISSIPPI RIVER. NOW...ON TO THE MUCH TALKED ABOUT STORM SYSTEM FOR THE WEEKEND. THE MODELS HAVE CERTAINLY HAD THEIR FUN WITH US...WHILE CONTINUING TO BRING THE REGION SOME PCPN...WHAT AND WHERE HAS VARIED ALMOST ON A DAY TO DAY...RUN TO RUN BASIS. NOW THAT THE SYSTEM HAS MOVED INTO THE SHORT-TERM...VARIANCES CONTINUE. I CERTAINLY DIDN/T ASK SANTA FOR THIS. ANYWAY...THE MODELS DO SEEM TO BE SETTLING MORE ON A SPLIT 500 MB FLOW TYPE SYSTEM...THAT MERGES TOGETHER AS IT PASSES INTO THE GREAT LAKES...STRENGTHENING FOR ITS TREK ACROSS THE NEW ENGLAND STATES. HOWEVER...THE DEVELOPMENT OF THEIR SFC LOWS ARE DIFFERENT...AND SO IS THEIR RESULTING QPF. THE NAM AND EC WOULD DEVELOP A SINGLE LOW CENTER...OVER WI/ILL BY 00Z SUN. THE GFS KEEPS THIS SYSTEM SPLIT YET...WITH LOW CENTERS OVER SOUTHERN CANADA AND ARK. EVENTUALLY THESE SOLUTION COME TOGETHER AS THE STORM MOVES EAST. THE 21Z SREF IS SIMILAR TO THE GFS WITH PLACEMENT OF ITS LOW CENTERS. THE GFS HAS BEEN FAIRLY CONSISTENT WITH A TWO-HEADED SYSTEM AS IT MOVES THROUGH THE GREAT LAKE STATES...ALTHOUGH A BIT SLOWER OVER ITS PAST FEW RUNS. THE EC HAS BEEN VARIABLE...BUT HAS MOVED FROM TWO LOWS TO ONE AS IT MOVES ACROSS THE REGION...WHILE THE NAM HAS HAD ONE LOW...JUST MOVED IT FARTHER SOUTH. IT WOULD SEEM THAT THE GFS HAS BEEN MORE CONSISTENT...AND IS FAVORED BY THE ENSEMBLES. THE DIFFERENCES ARE SIGNIFICANT IN THAT THE NAM/EC WOULD BRING STRONGER FORCING ACROSS THE FORECAST AREA...ALONG WITH THE DEFORMATION PCPN BAND WEST/NORTH OF THE SFC LOW. AS A RESULT...MORE QPF AND MORE SNOW POTENTIAL. THE GFS...CONVERSELY...IS MUCH LESS IN ITS QPF. WITH THE NAM...COBB OUTPUT WOULD PUT 3-5 INCHES ACROSS MUCH OF THE AREA. THE GFS IS LESS THAN AN INCH. THE SREF WOULD SUGGEST 1-2 INCHES...AND THE EC 2-4. DON/T THINK GOING TOWARD THE HIGH END...OR THE LOW END...IS THE WAY TO GO. WITH SUCH VARIABILITY IN THE MODEL SOLUTIONS...WILL OPT WITH SOMETHING IN THE MIDDLE...AND ALLOW LATER FORECASTS TO ADJUST UP OR DOWN...AS THE CASE MAY BE. ONE THING THE MODELS DO AGREE ON IS THAT SATURDAY/SAT EVENING WILL BE THE BEST TIME FOR SOME ACCUMULATING PCPN. BEFORE GETTING TO SNOW AMOUNTS...OR LACK THERE OFF...PRECIPITATION TYPE NEEDS TO BE QUESTIONED. AS THEY HAVE BEEN DOING...THE MODELS CONTINUE TO PULL CONSIDERABLE WARM AIR NORTHWARD AHEAD OF THE SYSTEM...AND THEN A QUICK COOL DOWN BEHIND THE ASSOCIATED COLD FRONT. LOOKING AT A NORTHWEST-SOUTHEAST RUNNING X-SECTION...THE NAM IS BY FAR THE WARMEST MODEL...SURGING +4 C AIR IN THE 900:850 MB LAYER NORTH OF RST AT 00Z SAT...WITH THE EC/GFS CLOSER TO +1. THE MODELS COOL THIS LAYER DOWN AS THE SYSTEM TRANSITIONS EAST... BUT THE NAM STILL STAYS FAIRLY WARM...WITH A DEEP //800 MB TO THE SFC// ABOVE ZERO LAYER FROM LSE TO THE SOUTHEAST AT 18Z SAT. BY 00Z ALL MODELS ARE COOL. THINK THE NAM MIGHT BE TOO AGGRESSIVE WITH THIS WARMING...AND WILL LEAN TOWARD THE EC/GFS IN THIS STEAD. STILL...THE TEMP PROFILES POINT TO SOME RAIN...OR RAIN/SNOW FOR PARTS OF NORTHEAST IOWA/SOUTHWEST WISCONSIN AS THIS SYSTEM MOVES IN...GRADUALLY CHANGING OVER TO SNOW BY SAT AFTERNOON. THIS TREND IS SHOWN WELL IN THE 21Z SREF DOMINANT PCPN TYPE DEPICTION. AS HAS BEEN THE CASE OVER THE PAST SEVERAL DAYS...THESE TEMP PROFILES SUPPORT EITHER RAIN OR SNOW...AND NOT SLEET OR FREEZING RAIN. AS FOR SNOW TOTALS...THE GREATER TOTALS WILL COME WHERE THE BEST FORCING COMES TOGETHER WITH THE COLDER AIR. SEEING AS THE FORECAST AREA WILL LIKELY LIE IN THIS TRANSITION ZONE ADDS FURTHER DIFFICULTLY IN TRYING TO PINPOINT TOTALS. AS MENTIONED PREVIOUSLY...SAT/SAT EVENING APPEARS TO BE THE BEST TIME FOR ACCUMULATIONS...AND WILL TAKE A MIDDLE OF THE ROAD APPROACH FOR AMOUNTS FOR NOW. 2 TO 4 INCHES SEEMS TO BE A REASONABLE PLACE TO START. LATEST HPC GUIDANCE IS FOLLOWING THE EC...WHICH WOULD PUT THE BETTER ACCUMS OVER CENTRAL/EASTERN WI INTO EASTERN IA. IF THE NAM HAS ITS WAY...IT WOULD BE OVER NORTHWEST WI INTO CENTRAL IA. TOUGH CALL...AND HATE TO BE WISHY WASHY...BUT MODEL CONFIDENCE DOES NOT LEND ITSELF TO ANYTHING TOO SPECIFIC AT THIS MOMENT. SO...CONFIDENCE REMAINS HIGH THAT THE REGION WILL RECEIVE SOME PRECIPITATION WITH THIS SYSTEM...CONFIDENCE ON AMOUNTS ARE NOT. A SNOW OR SNOW/RAIN OR EVEN JUST RAIN FOR AWHILE ALSO APPEARS QUITE LIKELY. JUST HOW FAR WEST AND NORTH THIS MIX OR RAIN WILL EXTEND IS NOT AS CLEAR. IT CERTAINLY HAS BEEN A VERY INTERESTING...BUT FRUSTRATING...SYSTEM TO TRY TO FORECAST. LONG TERM...SUNDAY THROUGH WEDNESDAY THE STORM SYSTEM CONTINUES TO PULL OFF TO THE EAST ON SUNDAY. SOME LIGHT SNOW/FLURRIES WILL BE POSSIBLE POST THE SYSTEM...IN THE WRAP AROUND REGION OF THE LOW...BUT MOSTLY TO THE NORTH AND EAST OF THE LOCAL AREA. HIGH PRESSURE THEN LOOKS TO BUILD IN FOR XMAS EVE/XMAS...AND SHOULD BRING SOME QUIET AND MOSTLY CLEAR CONDITIONS FOR THE HOLIDAY. FOR WED...A 500 MB TROUGH WILL START TO APPROACH THE REGION...HOWEVER CURRENT INDICATIONS BY THE GFS/EC IS TO TAKE THE BULK OF THE ASSOCIATED SHORTWAVE ENERGY EITHER NORTH OR SOUTH OF THE LOCAL AREA. AVIATION... A WEAK SHORT WAVE TROUGH WILL MOVE ACROSS THE AREA THIS AFTERNOON AND EVENING. ENOUGH FORCING WILL OCCUR FROM THIS WAVE TO POSSIBLY PRODUCE SOME LIGHT PRECIPITATION. FORECAST SOUNDINGS INDICATE THAT MVFR CEILINGS SHOULD DEVELOP THIS AFTERNOON AS THE WAVE APPROACHES. THE CLOUD LAYER DOES NOT LOOK TO RESIDE IN COLD ENOUGH TEMPERATURES TO HAVE ICE IN IT...SO ANY PRECIPITATION THAT DEVELOPS WILL EITHER BE DRIZZLE OR FREEZING DRIZZLE DEPENDING ON SURFACE TEMPERATURES. SOUTH TO SOUTHEAST WINDS WILL PUMP WARMER AND MOIST AIR INTO THE AREA OVERNIGHT WHICH IS EXPECTED TO RESULT IN IFR CEILINGS DEVELOPING. VISIBILITIES SHOULD REMAIN EITHER IFR OR MVFR THROUGH TODAY AND TONIGHT. 04 && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ RIECK wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1245 AM EST SAT DEC 22 2007 .AVIATION...(06Z TAFS) WAA FOG AND STRATUS ENTRENCHED ACROSS THE FORECAST AREA...BRINGING LIFR CONDITIONS AT BOTH TERMINALS. WEAK LL OMEGA COLLOCATED WITH A WEAK UPPER LEVEL IMPULSE HAS ALLOWED AREAS OF -DZ TO ALSO DEVELOP. 05Z OB AT SOUTH BEND HAS CONFIRMED SOME BREAKS IN LL VIS...AS 1SM HAS BEEN REPORTED. HOWEVER...EXPECT PREVAILING VIS AND CIGS TO REMAIN IN THE LIFR CAT THROUGH MID MORNING AS WAA OVER AMPLE SNOW FIELD WILL CONTINUE TO SUPPORT FOG FORMATION. LOOK FOR IMPROVING CONDITIONS TO IFR FROM LATE MORNING ON SOUTH TO NORTH WITH INTENSIFICATION OF THE LL WIND FIELD PER ADVANCING/DEEPENING SFC LOW PRESSURE. MAY EVEN SEE AREAS OF MVFR IN THE SOUTHEAST WHERE SNOW COVER IS MINIMAL AND SHOULD BE NEARLY ERODED BY AFTERNOON. COLD FRONT WILL ADVANCE TOWARD THE REGION TONIGHT AND ALLOW A CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS NEAR THE END OF THE PERIOD. WILL SEE IMPROVING CONDITIONS SUNDAY AS CAA AND DRY AIR PUSHES INTO THE REGION. THIS WILL ALLOW VAST IMPROVEMENT IN CIGS AND VISBYS. && .PREV DISCUSSION... /ISSUED 603 PM EST FRI DEC 21 2007/ UPDATE/AVIATION... 1ST PD GRIDS WERE OBVIOUSLY CORRUPT AND RECREATED BUT DRIVING GIST OF EARLY UPDATE IS TO GET NEEDED DENSE FOG ADVISORY OUT ASAP. 22Z SFC ANALYSIS SHOWS SIG LL MSTR SITTING JUST SOUTH ACRS CNTRL IN/SW OH AND SLOWLY ADVTG NWD AND WILL LEAD TO SIGNIFICANT ADVECTIVE DENSE FOG OVERTOP EXISTING SNOWPACK AND COLD GROUND. HAVE CONSIDERABLE DOUBTS AS TO THE VALIDITY OF WMFNT MIXING THROUGH CWA BY MORNING AND IMPLIED SLOWLY RISING TEMPS ESP IN LIGHT OF RUC HOLDING LARGE SCALE PRES FALLS INADV OF SRN PLAINS CYCLONE WELL WEST OVERNIGHT BUT WILL LEAVE THAT FOR LIKELY ADDNL UPDATE LTR THIS EVENING W/BTR SHOT OF SHOWER DVLPMNT XPCD WRN HALF IN ASSOCN/W INCREASING LARGE SCALE ISENTROPIC ASCENT. SHORT TERM (TONIGHT AND SATURDAY)... FOCUS TONIGHT WILL BE ON ADVANCING AREA OF INCREASED DEWPOINTS AND ANTICIPATED LOWER VISIBILITIES IN FOG. LOCATIONS SEEING DEWPTS IN THE 34 DEGREE OR HIGHER RANGE TO THE SOUTH AND WEST ARE SEEING THE DENSER FOG HOLDING ON. RUC40/NAM12 ALL SHOWING SLOWER ARRIVAL OF HIGHER DEWPOINTS...WITH BEST ADVECTION NOT OCCURRING TILL CLOSER TO 6Z IN THE SW AND SPREADING NORTH OVERNIGHT. AS A RESULT WILL MAKE FURTHER ADJUSTMENTS AND SLOW DOWN ONSET OF FOG AND DRIZZLE. KIWX 88D SHOWS SOME LIGHT RETURNS THAT MAY REACH THE GROUND IN THE FORM OF A BIT OF DRIZZLE OR FLURRIES. SOME CONCERNS AS STUBBORN AS THE DRIER FLOW IS INTO THE AREA THAT FOG MAY STRUGGLE TO GET TOO FAR NORTH. WILL REMAIN OPTIMISTIC AS 925/850 MB WINDS RAMP UP LATER TONIGHT AND SHOULD ALLOW THE MSTR TO GET ON THE MOVE. ON SATURDAY...CONTINUATION OF SNOWMELT AND HIGHER DEWPTS WILL CONTINUE IN INCREASING S TO SW FLOW. NAM/GFS/SREF HAVE ALL TRENDED SLOWER WITH ARRIVAL OF PRECIP NOT BRINGING IN TILL LIKELY OUTSIDE THIS PERIOD. DID NOT WANT TO DROP ALL POPS AT THIS POINT SO WENT DRASTIC DOWNWARD TREND AND REPOSITION OF BEST CHC FOR ANY PRECIP BY LATE AFTERNOON. WITH SLOWER ARRIVAL OF PRECIP...WARMER TEMPS MAY BE POSSIBLE ESPECIALLY IF FOG CAN LIFT OUT SOONER OR DOESN`T MATERIALIZE AS MUCH. FOR NOW HAVE LEFT THINGS ALONE TEMP WISE. LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... SATURDAY NIGHT THROUGH SUNDAY AMPLIFIED PATTERN ACROSS THE CENTRAL AND EASTERN CONUS WITH DEEP TROUGH OVER THE CENTRAL CONUS AND RIDGING ACROSS THE EAST. SFC WAVE MOVING UP FROM MID MS VALLEY TOWARDS LAKE MICHIGAN BY LATE SATURDAY NIGHT INTO EARLY SUNDAY. SFC LOW MOVES THRU THE LP OF MICHIGAN AN NORTH INTO CENTRAL ONTARIO BY SUNDAY AFTERNOON...BEFORE PULLING NORTHEAST INTO NORTHERN QUEBEC BY EARLY MONDAY. THERMAL PROFILE ACROSS THE REGION SUGGESTS ALL RAIN THRU THE OVERNIGHT BEFORE STARTING THE TRANSITION PERIOD AROUND DAYBREAK SUNDAY. MODELS HAVING BEEN SLOWING THE SYSTEM DOWN AND HAVE THEREFORE SLOWED THE PRECIP CHANGEOVER DOWN SOME AS WELL...AS THE H850 TEMPS DROP FROM +5 C TO BELOW 0C ACROSS THE ENTIRE REGION BETWEEN 12-15Z. ANY WRAP AROUND OR LAKE ENHANCED PRECIP WILL BE SNOW THEN THROUGH THE LATE MORNING INTO THE AFTERNOON WITH VERY STRONG CAA INTO THE REGION. TEMPS WILL CONTINUE TO DROP FROM LATE SATURDAY NIGHT THRU SUNDAY NIGHT...FROM 40S LATE SATURDAY NIGHT INTO THE 20S BY SUNDAY AFTERNOON...AND TEENS FOR LOWS OVERNIGHT INTO EARLY MONDAY. SIGNIFICANT AMOUNTS OF MOISTURE FOR THE SYSTEM TO WORK WITH WITH PWATS ABOVE 1 INCH EARLY SUNDAY...LIQUID QPF AMOUNTS WILL PUSH .5 INCHES FOR MOST OF THE AREA...BUT VERY LITTLE SNOW ACCUMS EXPECTED THRU THE PERIOD. MAINLY WITH LAKE ENHANCED OR LAKE EFFECT ACROSS THE FAR NW PORTIONS OF THE AREA AND ACROSS THE FAR NORTHERN TIER OF COUNTIES AS THE FLOW ACROSS THE LAKE BECOME MORE WESTERLY WITH TIME...MAYBE AN INCH OR TWO. UPPER LEVEL LOW STARTS TO PUSH INTO THE GREAT LAKES EARLY SUNDAY AND THRU THE DAY...VERY TIGHT PRESSURE GRADIENT ACROSS THE REGION WITH NORTHWEST/WEST FLOW THROUGH THE DAY. GUSTY WINDS WILL INCREASE FROM EARLY SUNDAY THROUGH SUNDAY AFTERNOON. LAKE EFFECT SNOW ACROSS THE NORTHERN TIER OF THE CWA WILL CONTINUE TO BE A POSSIBILITY WITH DELTA T/S REACHING LEVELS OF -15 OR MORE BY SUNDAY EVENING. MONDAY THROUGH FRIDAY SPLIT FLOW ACROSS THE WEST BECOMES MORE CONFLUENT ACROSS THE EASTERN CONUS...UPPER LEVEL LOW PUSHING EAST THRU THE ST LAW RVR VALLEY WITH ANOTHER SW CONUS SHRTWV PULLING OUT AND WEAKENING AS IT MOVES TO THE NORTHEAST. LARGE SFC HIGH ENTRENCHED ACROSS THE GREAT LAKES/OH AND MS VALLEYS INTO TUESDAY...WITH SOME UPPER LEVEL RIDGING BUILDING ACROSS THE REGION TUESDAY INTO WEDNESDAY WITH ANOTHER UPPER LEVEL LOW OVER THE SW CONUS. BELOW NORMAL TEMPS EXPECTED MONDAY...SLIGHTLY WARMER AND NEAR SEASONAL VALUES OF LOWER TO MID 30S FOR HIGHS. DRY THRU THE PERIOD...A SMALL CHANCE OF LAKE EFFECT ACROSS THE FAR NORTH EARLY MONDAY. MID RANGE MODELS HAVING SOME ISSUES THRU THE END OF THE PERIOD...SIGNIFICANT DISAGREEMENTS WITH RESPECT TO THE STRENGTH AND TIMING BUT THE LATEST GFS AND THE ENSEMBLE MEANS HAVE BEEN SHOWING SOME SIGNIFICANT WINTRY POTENTIAL TOWARDS THE END OF THE MONTH. FIRST POTENTIAL SIGNIFICANT SYSTEM WILL BE WEDNESDAY NIGHT INTO THURSDAY TIMEFRAME. CUT-OFF LOW PUSHES EAST INTO THE RIDGE...POSSIBLE NEG TILT WITH SFC LOW MOVING FROM THE LOWER MS VALLEY INTO THE REGION. MOISTURE SHOULD NOT BE A CONCERN WITH THE GULF APPEARING TO BE OPEN...PWATS AT OR MORE THAN DOUBLE NORMAL FOR THE TIME OF YEAR. THE TRACK STILL UNCERTAIN...WILL LIMIT THE DETAILS...BUT CURRENT BUFKIT AND MODEL THERMAL PROFILES WOULD SUGGEST ALL SNOW. HAVE UPPED POPS TO 50 THRU THE PERIOD WITH HIGHER CONFIDENCE THAT A SYSTEM WILL BE THERE...BUT LOWER CONFIDENCE ON TRACK AND P-TYPE AS THE MODELS THIS SEASON HAVE HAD SOME SIGNIFICANT SHIFTS OVER TIME OF UP TO 300-500 MILES. ANOTHER DIGGING UPPER LEVEL LOW INTO THE SOUTHWEST LATE IN THE WEEK...THURSDAY INTO FRIDAY...WILL START KICK OUT AND WILL ALLOW FOR THE SECOND POTENTIAL WINTER SYSTEM BY THE WEEKEND. PRECIP COULD START AS SOON AS FRI NIGHT/SATURDAY...WITH TRACK AND P-TYPE HIGHLY UNCERTAIN...STILL 6-7 DAYS OR MORE OUT MUCH TO CHANGE MOST LIKELY. STRONG MODEL SUPPORT FROM THE GFS ENSEMBLES. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...DENSE FOG ADVISORY UNTIL 10 AM EST /9 AM CST/ THIS MORNING FOR INZ003>005-008-009-012-014-016>018. DENSE FOG ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR INZ006-007. DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR INZ013-015- 020-022>027-032>034. MI...DENSE FOG ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR MIZ077>081. OH...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR OHZ004-005- 015-016. DENSE FOG ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR OHZ001-002. DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR OHZ024-025. LM...NONE. && $$ SHORT TERM...FISHER LONG TERM...SCHOTT UPDATE...HOLSTEN AVIATION...CHAMBERLAIN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 347 AM CST SAT DEC 22 2007 .SYNOPSIS... IMPENDING SYSTEM CURRENTLY PULLING OUT OF ROCKIES WITH SEVERAL SHRT WVS ROTATING AROUND UPPER LOW NEAR NM/CO BORDER. ANOTHER WEAKER WV NOTED INTO NWRN IA TRYING TO SPREAD LGT PCPN INTO THAT AREA. VERY STRONG QG FORCING IN IMMEDIATE VICINITY OF THIS COMPACT LOW BUT HAS YET TO SPREAD TOO FAR INTO NE OR KS WITH SIGNIFICANT PCPN STILL RELEGATED TO ERN CO/WRN KS. NRN STREAM SHRT WV OVER SERN SASKATCHEWAN WITH ASSOCIATED FORCING NOT A FACTOR FOR THE TIME BEING. 08Z SFC ANLYS PLACES FRONTAL BOUNDARY FROM JUST W OF TWIN CITIES TO SUBTLE LOW JUST N OF LWD THEN TRAILING INTO OK. BROAD PRES RISES NOTED THROUGHOUT PLAINS WITH VERY DRY UPSTREAM AIRMASS. && .DISCUSSION... OBVIOUS PRIMARY CONCERN WILL BE IMPACT OF WEEKEND STORM...BUT WILL HAVE TO DEAL WITH DENSE FOG ADVY FIRST. WITH INCREASING NWLY WINDS ALREADY TO ICL-CIN-EST LINE WITH CFP HAVE SHIFTED ADVY EWD AND IS NOW IN EFFECT E OF THESE AREAS TIL 15Z AND BASICALLY I35 CORRIDOR EWD TIL 18Z. TEMPS SHOULD BE FALLING SO FORECAST HIGHS ARE VERY CLOSE TO CURRENT READINGS. REGARDING THE WINTER STORM...NAM SEEMED TO INITIALIZE JUST A TAD BIT BETTER AT 00Z WITH SLIGHTLY DEEPER FEATURES THROUGH DEPTH OF ATMOSPHERE. HOWEVER WILL BE FAVORING GFS AS WELL AS 00Z SPC WRF AND THEIR MORE WLY QPF SOLUTION. CONFIDENCE NOT THE GREATEST WITH 00Z ECMWF AND 06Z NAM STILL GOING FARTHER E. HOWEVER GFS...ALONG WITH 06Z RUC...SEEM TO HAVE BETTER HANDLE ON CURRENT WX AFTER 06Z AND EXTRAPOLATION OF DEVELOPING DEF ZN INTO IA.. THIS WOULD SUGGEST THAT FARTHER W SOLUTION THE WAY TO GO WITH HEAVIER SNOWS BACK INTO DSM METRO AND POINTS S AND E. MODEL BIASES OFTEN PLACE HEAVIER ACCUMS TOO FAR SE...WITH THE NAM OFTEN SEEMING TO BE SHADING HIGHER QPF AMOUNTS TOO CLOSE TO CONVECTION AND NOT EMPHASIZING DEF ZN ADEQUATELY. MUCH LIKE YESTERDAY...FORCING IN DENDRITIC LAYER SEEMS TO BE IN H5/H6 LAYER OR AROUND 300/305K ISENT SFCS. UVM IN THESE AREAS OF CONCERN SPREAD NEWD INTO IA BY 18Z BUILDING ON SE-NE ORIENTED BAND ALREADY DEVELOPING ON RADAR. ALTHOUGH SOME THETA-E ADVECTION AND FRONTOGENETICAL FORCING IS NOTED...BRUNT OF UVM SEEMS TO BE DRIVEN BY DPVA AS SHRT WV LIFTS OUT. THIS STILL RESULTS IN STRONG OVERALL QG FORCING INTO THE AFTN BEFORE REACHING FAR ERN PORTIONS THIS EVE. SERN FRINGE OF THIS AREA WILL SEE THETA-E LAPSE RATES AND EPV GOING NEGATIVE SO EXPECT STATIC STABILITY WILL BE QUITE LOW. LIGHTNING HAS ALREADY BEEN OBSERVED NEAR LOW CORE AND WOULD NOT BE SURPRISED TO BRIEFLY SEE SOME CONVECTIVE ELEMENTS BEFORE STABILITY MIN MOVES INTO IL THIS EVE. CURRENT SNOW TOTALS VARY FROM 4-7 INCHES IN THE WARNING...BUT COULD SEE ISOLD HIGHER AMOUNTS IF CONVECTION PANS OUT. THIS CONVECTION AND POTENTIAL LATENT HEAT RELEASE MAY BE ANOTHER REASON TO FAVOR MORE NWLY GFS SOLUTION WITH LOWER PRESSURES INTO COLDER AIR. ALSO JUST NOTICED 06Z NAM HAS STRONG DENDRITIC FORCING BACK INTO ALO-OTM CORRIDOR THROUGH 06Z BUT QPF NOT FAR ENOUGH WWD TO REFLECT THAT. ANOTHER REASON TO FAVOR 00Z GFS. HAVE SWITCHED PREVIOUS WATCH TO WINTER STORM WARNING AND ADVY. WRNG IS ESSENTIALLY WHERE SNOW AMOUNTS ARE EXPECTED TO BE 4 INCHES PLUS. THIS FUDGES CRITERIA SOMEWHAT...BUT BLENDS WELL INTO ADJACENT HEADLINES AND AM NOT GOING TO WORRY ABOUT DETAILS CONSIDERING THE BLOWING SNOW POTENTIAL. JUST TO THE NW...SNOW AND BLOWING SNOW ADVY IN EFFECT WHERE AMOUNTS SHOULD REACH 1-4". SFC PRESSURES GO FROM JUST ABOVE 1000MB THIS EVE TO 985 OR LESS BY MIDDAY SUN WHEN LOW REACHES GREAT LAKES. THIS WILL REALLY CRANK THE WINDS UP WITH IMPRESSIVE ISALLOBARIC COMPONENT AND PRES GRADIENT LIKELY PUSHING WINDS INTO BLIZZARD WARNING POTENTIAL ERN HALF. NRN IL LOOKS TO BE HIT ESPECIALLY HARD. THIS WOULD BE LATE 2ND PERIOD SO WILL LEAVE THAT UPGRADE FOR LATER SHIFTS BUT WOULD NOT BE SURPRISED IF IT IS REACHED EARLY SUN WITH PROJECTED GUSTS INTO THE LOWER/MIDDLE 30KTS. EXPECT PLENTY OF WRAP AROUND STRATUS AND POTENTIALLY FLURRIES CONTINUING LATER SUN AND SUN NIGHT. NO CHANGES TO LATER PERIODS. CONSIDERING STRENGTH OF CAA...SNOW COVER AND PERSISTENT LOW CLOUDS HAVE GONE JUST BELOW COOLEST GUIDANCE FOR HIGHS SUN. DO NOT SEE MUCH THERMAL CHANGE SUN NIGHT WITH MORE STRATUS AND WINDS KEEPING THINGS MIXED SO ONLY WENT WITH SEVERAL DEGREE DIURNAL DROP TOWARD HIGHER END OF GUIDANCE. LOW LEVEL MOISTURE LINGERS INTO MON AND WITH INVERSION STILL IN PLACE AROUND SOLAR MIN DO NOT SEE MUCH HOPE FOR REBOUND. HAVE CLIPPED CURRENT MON FORECAST QUITE A BIT NOW GOING AT LEAST A CATEGORY BELOW COOLEST GUIDANCE...WHICH IS A BLEND OF RAW TEMPS. MAY HAVE TO GO EVEN FURTHER IN UPCOMING PACKAGES. && .AVIATION...22/06Z LIFR CONDITIONS WILL PERSIST OVER MUCH OF THE AREA UNTIL THE EARLY MORNING HOURS WHEN A COLD FRONT WILL MIX IN DRIER AIR. THE FRONT WILL BE ACCOMPANIED BY MIXED PRECIPITATION...CHANGING TO ALL SNOW THROUGH THE AFTERNOON. HAVE INCLUDED MENTION OF BLOWING SNOW AS WELL FOR ALL SITES EXCEPT FOD WITH INCREASING NW WINDS THIS AFTERNOON AND EVENING. && .DMX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVY ALONG AND E OF CRESTON-BOONE-FOREST CITY LINE TIL 15Z...AND LWD-DSM-AMW-HAMPTON LINE TIL 18Z. WINTER STORM WARNING BASICALLY ALONG AND EAST OF CORNING-AMES-HAMPTON LINE 18Z-12Z. SNOW AND BLOWING SNOW ADVY BASICALLY ALONG AND EAST OF DNS-CIN-AXA LINE BLENDING INTO WARNING...15Z-12Z. && $$ SMALL/ALBRECHT/KINNEY ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 320 AM EST SAT DEC 22 2007 .SYNOPSIS... HIGH PRESSURE WILL SLIDE SOUTHEAST OF THE REGION TODAY. WARMER AIR WILL BE PULLED NORTH ON INCREASING SOUTHEASTERLY WINDS AS A COLD FRONT APPROACHES ON SUNDAY. THE FRONT WILL MOVE THROUGH SUNDAY NIGHT FOLLOWED BY GUSTY WINDS AS LOW PRESSURE MOVES BY TO THE NORTH ON MONDAY. HIGH PRESSURE WILL BUILD IN ON TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... MAIN CHALLENGE RIGHT OFF THE BAT IS THE SCU DECK SHROUDING MUCH OF THE CWA EARLY THIS MORNING AND TEMPS. SRG NOT HANDLING SCU DECK WELL AT ALL W/THE EXCEPTION OF THE RUC WHICH INITIALLY HAD IT AND THEN ERODES IT OUT TOO QUICKLY. STG INVERSION IN PLACE ALLOWING THE SCU DECK TO HANG ON LONGER. HOWEVER...LATEST SATL IR IMAGERY SHOWING THIS CLOUD SHIELD MOVG E AND BREAKING UP. CONTINUED THIS TREND TODAY AS HIGH PRES MOVES SE AND SSW FLOW ALOFT TAKES OVER. THEREFORE...THINKING SUNSHINE MOST OF THE DAY TODAY WITH WARMER TEMPS. DECIDED CUT MOS GUIDANCE TEMPS BY 2-3 DEGS FOR MAXES TODAY ESP FOR LOW LYING REGIONS WHERE INVERSION WILL HOLD LONGER. MOS HAS BEEN RUNNING TOO WARM OVER THE LAST FEW DAYS. SKY GRIDS ARE A REFLECTION OF THE GFS40. TONIGHT...NO HEADLINES ATTM. DECIDED TO BACK OFF ON SNOW CHCS TIL AFT 06Z AND HIGHEST POPS ARE ACROSS THE FAR WNW W/30% POPS. PRECIP/THICKNESS TOOL PUTS SN TO START OUT AHEAD OF APCHG FRONTAL SYSTEM AND THIS LOOKS GOOD GIVEN ALL PARTIAL THICKNESS VALUES INDICATING FROZEN PRECIP. DAYCREW CAN ASSESS THINGS FURTHER W/LATER GUIDANCE. WAA ALOFT WILL GRADUALLY BEGIN TO WORK IN OVERNIGHT W/TEMPS DROPPING OFF EARLY ON AND THEN LEVELING OFF. MOS GUIDANCE WAS LOADED AND THEN LOWERED THEM BACK A FEW DEGS ONCE AGAIN ESP FOR LOW LYING AREAS. ANOTHER ISSUE IS THE POTENTIAL FOR STRATUS TO WORK IN GIVEN SLY FLOW GETTING STARTED AFT 06Z THROUGH 5K FT. THEREFORE...THINKING SKIES WILL GO CLOUDY AFT 06Z. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... HIGH PRESSURE WILL MOVE EAST EARLY SUNDAY. MODELS IN GOOD AGREEMENT WITH REGARD TO A PERIOD OF PRECIPITATION DEVELOPING DURING SUNDAY AND INTO SUNDAY NIGHT IN ADVANCE OF AN OCCLUDED FRONT APPROACHING FROM THE WEST. INITIALLY THERE WILL BE ENOUGH COLD AIR IN THE LOWER LEVELS FOR A PERIOD OF MIXED PRECIPITATION BEFORE A STRONG SOUTHERLY FLOW OF MILDER AIR CHANGES ANY MIXED PRECIPITATION TO ALL RAIN BY SUNDAY EVENING ALL AREAS. ANOTHER ISSUE WILL BE THE POTENTIAL FOR STRONG WINDS ACROSS THE DOWNEAST COAST SUNDAY EVENING WITH GFS INDICATING IN 850 TO 925 MB JET IN EXCESS OF 50 KTS LATER SUNDAY EVENING. A HIGH WIND WATCH WILL LIKELY BE NEEDED FOR LATER SUNDAY AND INTO SUNDAY NIGHT. THE OCCLUDED FRONT WILL CROSS MOST OF THE FORECAST AREA BY EARLY MONDAY MORNING. AN UPPER LEVEL LOW WILL MOVE ACROSS THE REGION DURING MONDAY AND INTO MONDAY EVENING WITH THE CHANCE FOR SNOW SHOWERS ACROSS NORTHERN AREAS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... HIGH PRESSURE WILL BUILD ACROSS THE FORECAST INTO MIDWEEK. ANOTHER LOW WILL APPROACH THE REGION FOR LATE WEEK WITH THE CHANCE FRO SOME SNOW SHOWERS. TEMPERATURES WILL BE NEAR NORMAL THROUGH THE PERIOD. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... VFR INTO EARLY TONIGHT AND THEN THINKING HERE IS THAT THE STRATUS DECK MENTIONED ABV WILL WORK INTO THE TAF SITES AFT 06Z W/CIGS DROPPING BLO 1K FT. LOOKS LIKE IFR CONDITIONS SHOULD HOLD RIGHT INTO SUNDAY NIGHT AND THEN CONDITIONS LOOK TO GO MVFR MONDAY MORNING AND HOLDING THAT WAY ACROSS THE N WHILE KBGR AND KBHB GO VFR AS NWLY FLOW TAKES OVER. MVFR ACROSS THE N TUESDAY W/VFR ELSEWHERE. && .MARINE... NEAR TERM: NO HEADLINES IN SIGHT. WNAWAVE GUIDANCE CATCHING ON PER LATEST OBS AND WENT W/IT. 2-3 FOOT SEAS WILL DROP BACK TO LESS THAN 2 FT THIS AFTERNOON INTO EARLY TONIGHT. SEAS WILL GRADUALLY BUILD AFTER MIDNIGHT AS S FLOW BEGINS TO SET IN. SHORT TERM: WIND/SEAS WILL INCREASE TO GALE FORCE IN ADVANCE OF THE FRONT LATER SUNDAY AND SUNDAY NIGHT. WINDS WILL THEN CONTINUE AT GALE FORCE OR STRONG SCA INTO MONDAY. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...HEWITT SHORT TERM...DUDA LONG TERM...DUDA AVIATION...HEWITT MARINE...HEWITT/DUDA me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 415 AM EST SAT DEC 22 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW OVER NAMERICA WITH NRN BRANCH TROF OVER SRN SASKATCHEWAN AND A SRN BRANCH TROF ACRS THE SRN ROCKIES. UPR RDGING IN BOTH BRANCHES HAS SET IN OVER THE GRT LKS AS RELATIVELY WARM AIR FOR THE SEASON HAS SPREAD AS FAR N AS ONTARIO IN THE GENERAL SSW FLOW AHEAD OF THE TROFS TO THE W. SHRTWV LIFTING OUT OF SRN BRANCH TROF IS CURRENTLY MOVING INTO THE UPR MS VALLEY. AREA RAOBS SHOW QUITE A BIT OF LLVL MSTR...SO LO CLD IS WDSPRD OVER THE AREA WITH SOME LOCALLY DENSE FOG OVER THE CNTRL ZNS WITH MOIST UPSLOPE SE FLOW BTWN DEPARTING HI PRES OVER SE CAN AND LO PRES TO THE W. FOR THE MOST PART...SFC TEMPS OVER THE FA ARE ABV 32. QUITE A BIT OF HI CLD STREAMING NEWD AS WELL...BUT RAOBS SHOW PLENTY OF DRY AIR UPSTREAM AT H85-7. FOR INSTANCE...H7 DWPT DEPRESSION AT OMA IS 23C AND H85/7 DWPT DESPRESSIONS AT DVN ARE 35C AND 40C RESPECTIVELY. SO PCPN ASSOCIATED WITH THIS SYS IS PRETTY MUCH RESTRICTED TO NRN MN/WRN LK SUP WHERE GFS/NAM SHOW SHARPER ISENTROPIC LIFT ON THE 290K SFC. OTRW...MUCH COLDER AIR ASSOCIATED WITH THE NRN BRANCH TROF IS SHOWING UP IN THE NRN PLAINS WITH SFC TEMPS FALLING BLO 10F IN ND BEHIND COLD FNT ASSOCIATED WITH NRN BRANCH SHRTWV. FCST CONCERNS ARE NMRS THIS PACKAGE WITH DEGREE OF PHASING BTWN SEPARATE BRANCHES/SHRTWVS NOTED ABV AND IMPACT OF TRACK/STRENGTH OF SFC LO PRES THE CHALLENGE. ALTHOUGH THE NUMERICAL MODELS OFTEN HAVE DIFFICULTY IN THESE SCENARIOS AND THE PHYSICAL DISTANCE BTWN THE FEATURES ATTM WOULD SUG A SLOWER INTERACTION...THE 00Z NAM/GFS ARE REMARKABLY SIMILAR IN DEPICTING THE DVLPMNT OF A DEEP SFC LO FCST TO REACH NR GRB AT 12Z SUN AND THE POTENTIAL FOR A MAJOR WINTER STORM OVER ESPECIALLY THE WRN COUNTIES. WL NEED TO DETERMINE WHETHER OR NOT TO UPGRADE ANY OF THE GOING WATCHES TO WRNGS. ON THE OTHER HAND...TDAY SHOULD BE RELATIVELY UNEVENTFUL. AMPLE LLVL MSTR FCST TO CONTINUE FLOWING INTO THE UPR LKS IN LARGER SCALE SLY FLOW...BUT DRYNESS OF H85-7 UPSTREAM SUGS NUMERICAL GUIDANCE MAY BE A BIT AGGRESSIVE AT GENERATING PCPN OVER ALL BUT THE WRN ZNS TDAY DESPITE SOME PERSISTENT LARGER SCALE ISENTROPIC LIFT SHOWN ON THE 290-295K SFCS. WL CARRY AREAS OF DZ/FOG OVER THE CNTRL ZNS THRU THE DAY WITH JUST PTCHY DZ/FOG OVER THE E. WITH TEMPS ALREADY ABV 32 ALMOST EVERYWHERE...SUSPECT PCPN WL BE LIQUID. BETTER CHC FOR PCPN LOOKS TO BE OVER THE WRN ZNS ESPECIALLY THIS AFTN WITH ARRIVAL OF INVERTED TROF TO THE N OF SFC LO PRES GFS/NAM FCST TO DVLP IN THE MID VS VALLEY AHEAD OF SRN BRANCH TROF LIFTING NEWD FM THE SRN ROCKIES. EVEN THERE...PCPN WL START AS RA WITH SO MUCH LLVL WARM AIR IN PLACE...BUT FCST SDNGS/WBZ SHOW PCPN WL MIX WITH OR CHG TO ALL SN IN GOGEBIC/ONTONAGON COUNTIES WITH ARRIVAL OF LLVL COLDER AIR BEHIND INVERTED TROF. SFC OBS TO THE W SHOW TEMPS FALLING QUICKLY BLO 32 IN THE WAKE OF THIS BDNRY...SO NAM/GFS FCST PCPN TYPE THERE SEEMS RSNBL. FOR TNGT...NAM/GFS IN EXCELLENT AGREEMENT SHOWING DETAILS OF PHASING BRANCHES...WITH RDPLY DEEPENING LO PRES MOVING TO NEAR GRB BY 12Z SUN. INCRSG UPR DIFFLUENCE/H5 HGT FALLS/DEEP LYR QVECTOR CNVGC TO THE NE OF DVLPG NEGATIVELY TILTED CUTOFF LO AT H5 JUST TO THE SW OF MPX ESPECIALLY AFT 06Z WL SUPPORT INCRSGLY WDSPRD PCPN. TRACK OF SFC LO WL DRAW ENUF WARM AIR INTO THE ERN/NCNTRL FA TO MAINTAIN JUST RA... BUT OVER THE W THE COMBINATION OF INTENSE UVV/DYNAMIC COOLING AND INFLUX OF LLVL COLD AIR WL CAUSE THE PCPN TO BE SN OR CHG TO SN. USING NAM FCST WBZ HGT OF 1500FT/H925-85 THKNS OF 676M AS A GUIDE... LOOK FOR THE RA/SN LINE TO BE FM CMX-HURON MNTS-CRYSTAL FALLS OR SO BY 12Z SUN ON THE COLD SIDE OF THE H85 LO TRACK. ON SUN...SFC LO PROGGED TO MOVE TO SLOWLY TO ARND SCNTRL LK SUP BY LATE IN THE DAY AS UPR LO SLIDES INTO THE CNTRL GRT LKS...SUPPORTING 12HR H5 HGT FALLS UP TO 150M. PCPN WL GRDLY CHG TO SN WITH DYNAMIC COOLING...BUT WARM LYR ALF/TROWAL FEATURE WL RETARD CHGOVER NEAR LK SUP OVER THE NCNTRL...ESPECIALLY WITH N FLOW OFF THE WARM LK WATERS. IN FACT...THE PCPN MAY CHG TO SN FASTER OVER THE E AND NEAR LK MI THAN AT THE CITY OF MQT. OTRW...ARRIVAL OF HIER SPECIFIC HUMIDITY FM THE NNE TO THE W OF LO WL ENHANCE PCPN RATES ESPECIALLY WHERE LLVL NNE FLOW UPSLOPES AND WHERE CROSS SECTION SHOWS THETA-E DCRSG A BIT WITH HGT ABV TROWAL ACRS THE NCNTRL W OF MQT. WHERE THE PCPN FALLS AS SN...INCRSG WINDS WL CAUSE CONSIDERABLE BLSN. BUT FCST SCENARIO ATTM SEEMS TO SUG WINDS/BLSN WL NOT BE AS SGNFT AS PREVIOUSLY THOUGHT. SINCE THE HEAVIEST SN WL FALL ONLY LATE IN THE SECOND PD AND THE THIRD PD...OPTED TO KEEP GOING WATCH AND NOT UPGRADE TO WRNG...ESPECIALLY SINCE 06Z NAM APPEARS TO BE SLOWER BRINGING IN THE SHARPER DYNAMICS. EXPECT ANY PCPN TO BE ALL SN SUN NGT BUT THEN TO GRDLY DIMINISH AS HGTS RISE FAIRLY SHARPLY IN THE WAKE OF THE DEPARTING UPR LO WITH UPR CNVGC/DNVA/DEEP LYR QVECTOR DVGC. INCOMING AIRMASS DOES NOT APPEAR PARTICULARLY COLD (H85 TEMPS ARND -10C) EITHER WITH HIER MSTR TENDING ...SO LES SHOULD NOT GET OUT OF HAND. BUT PERSISTENT CYC FLOW WL CONT -SHSN THRU THE NGT ALBEIT AT A LIGHTER RATE. COORDINATED WITH APX/GRB/DLH. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... PREVAILING SSE UPSLOPE FLOW AND ADDED LOW-LEVEL MOISTURE FROM SNOWMELT SHOULD CONTINUE IFR CONDITIONS AT KSAW...WITH THE EXCEPTION OF PREVAILING LIFR CONDITIONS FROM 06-15Z. EXPECT IFR CIGS AT KCMX THROUGH THE PERIOD AS VSBYS FALL FROM MVFR TO IFR TOWARD 12Z SAT. LOOK FOR CONDITIONS AT KCMX TO TRANSITION TO LIFR BY SAT NIGHT WITH INCREASED MOISTURE FROM EXPECTED RAINFALL AND LIGHT UPSLOPE ERLY FLOW. EXPECT STEADIER RAINFALL SAT AFT INTO SAT NIGHT AS WARM ADVECTION INCREASES ACROSS THE REGION. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... AFTER A GENERAL QUIET PERIOD ON LAKE SUPERIOR THROUGH TONIGHT WITH WINDS NO HIGHER THAN 25 KT (GREATEST NEAR WHITEFISH POINT)...EXPECT WINDS TO REALLY INCREASE SUNDAY. THIS RAPID INCREASE IS DUE TO LOW PRESSURE OVER SOUTHERN MISSOURI THIS EVENING THAT RAPIDLY DEEPENS AS IT HEADS DUE NORTH TOWARD CENTRAL UPPER MICHIGAN. AS THE LOW MOVES TO NEAR MARQUETTE EARLY SUNDAY AFTERNOON...NORTH TO NORTHEAST WINDS ACROSS WESTERN LAKE SUPERIOR SHOULD INCREASE TO GALES. BY SUNDAY EVENING...THERE IS A CHANCE THEY COULD INCREASE TO STORM FORCE... ESPECIALLY NEAR ISLE ROYALE. AS THE LOW SHIFTS FROM NEAR MUNISING SUNDAY EVENING INTO NORTHWEST QUEBEC LATE IN THE NIGHT...WINDS WILL QUICKLY RELAX...DROPPING BELOW GALES ACROSS ALL OF LAKE SUPERIOR JUST AFTER MIDNIGHT SUNDAY NIGHT. WINDS BELOW 30 KT ARE THEN EXPECTED FOR CHRISTMAS EVE INTO WEDNESDAY...WITH A HIGH PRESSURE RIDGE CROSSING MONDAY NIGHT AND A LOW PRESSURE TROUGH CROSSING TUESDAY NIGHT. && .MQT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY MORNING FOR MIZ001>005-009-010-084. WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY AFTERNOON FOR MIZ011. && $$ DISCUSSION...KC AVIATION...VOSS MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 408 AM EST SAT DEC 22 2007 .SHORT TERM...TODAY AMPLIFIED UPPER LEVEL PATTERN WILL CONTINUE TO EVOLVE OVER THE NEXT 24 HOURS...AS THE UPPER RIDGE AXIS SHIFTS EAST AND A DEEPENING UPPER LOW CURRENTLY OVER THE FOUR CORNERS EJECTS NORTHEAST TOWARD THE GREAT LAKES. FOR TODAY...MAIN ISSUE WILL BE THE PERSISTENT FEED OF DEEP LOW LEVEL MOISTURE. THUS FAR THIS MORNING...DESPITE DEWPTS CLIMBING INTO THE LOW/MID 30S...SEEING JUST ENOUGH OF AN EASTERLY COMPONENT TO THE LOW LEVEL WIND FIELD THAT DENSE FOG AND REPORTS OF DRIZZLE REMAIN SPOTTY. AS WINDS GRADUALLY VEER TOWARD THE SOUTH...EXPECT DEEPER SATURATION TO OCCUR...ESPECIALLY THROUGH THE MORNING HOURS PRIOR TO THE ONSET OF BETTER MIXING BY AFTERNOON. THUS...WILL HANG ON TO A LOW CHC POP...AS A FEW LOCATIONS COULD SEE SMALL MEASURABLE AMOUNTS WITHIN ANY HEAVIER AREAS OF LGT RAIN/DRIZZLE. PERSISTENT WEAK WAA WILL WORK OFF THE MILD MORNING START...PUSHING HIGHS AT LEAST 10 DEGREES ABOVE NORMAL...WITH READINGS ACROSS THE AREA THE WARMEST IN OVER 3 WEEKS. BASED ON CURRENT/UPSTREAM CONDITIONS...AND PROJECTED 850 MB TEMPERATURES...HIGHS RANGING FROM LOWER 40S ACROSS THE SAGINAW VALLEY/THUMB REGION TO UPPER 40S NEAR THE OHIO BORDER LOOK ATTAINABLE DESPITE A SOLID CLOUD DECK AND THE RAPIDLY MELTING SNOWPACK. && .LONG TERM...TONIGHT THROUGH FRIDAY TWO VIGOROUS...WELL DEVELOPED...MIDLEVEL VORTICES DIGGING INTO SOUTHERN ALBERTA/NEW MEXICO WILL PHASE ACROSS THE UPPER MISSISSIPPI RIVER VALLEY LATER TONIGHT. THE TREND OF THE 00 UTC NUMERICAL GUIDANCE HAS AGAIN BEEN A TAD SLOWER WITH THE SURFACE CYCLONE EVENT FOR THIS WEEKEND. THE MODELS ARE STILL EXEMPLIFYING A SURFACE CYCLONE THAT WILL TRACK NORTHWARD THROUGH CHICAGO AND INTO LAKE MICHIGAN THIS EVENING. THE SURFACE LOW...WHILE CONTINUING STRAIGHT NORTHERLY...DEEPENS SOME 12 TO 15 MB IN 12 HOURS CENTERING ON EASTERN LAKE SUPERIOR/EASTERN U.P. BY SUNDAY AFTERNOON. WITH TIME OF YEAR CONSIDERATIONS/WARMISH LAKE TEMPERATURES WILL ERR ON THE SIDE OF THE DEEPER SOLUTION. FOR TONIGHT...EXPECTING THE EVENING TO BE RELATIVELY QUIET AS RESIDUAL DRY MIDLEVEL AIR LINGERS. THEN AFTER MIDNIGHT...SECONDARY MOISTURE PUSH ARRIVES FROM THE SOUTH...ALONG WITH STRONG 700-500MB FRONTOGENESIS. WITHIN EASTERN FLANK OF RAPIDLY DEEPENING LOW PRESSURE SUPPORTS A WIDESPREAD AREA OF CATEGORICAL POPS FOR RAIN (UP TO ONE HALF INCH). LATEST GFS CAME IN HINTING AT SOME ELEVATED INSTABILITY TONIGHT...WHILE THE NAM CHECKED IN MORE BEARISH. EXAMINING MODEL SOUNDINGS DOES SUGGEST AT SOME STEEP MIDLEVEL LAPSE RATES OVERNIGHT BUT AMOUNT OF ELEVATED INSTABILITY IS LOW. A JAW DROPPING LOW LEVEL JET OF PLUS 75 KNOTS AT 850MB WILL CERTAINLY ALLOW FOR CONVERGENCE AND FORCING...BUT WITH DECEMBER CLIMATOLOGY IN MIND DECIDED AGAINST ANY THUNDER MENTION. THE IMPRESSIVELY SHARP SURFACE COLD FRONT IS PROGGED TO WHISTLE THROUGH MOST OF THE FORECAST AREA BETWEEN 10AM AND NOON SUNDAY. A WIND ADVISORY MAY BE NEEDED AS WESTERLY WINDS COULD POTENTIALLY GUST OVER 45 MPH TRAILING THE COLD FRONT. A QUICK CHANGEOVER TO SNOW IS LIKELY AS COLD AIR ADVECTION IS HIGHLY IMPRESSIVE. BUT...WITH STRONG SUBSIDENCE TRAILING SUCH A STRONG FRONTAL CIRCULATION...SIGNIFICANT PRECIPITATION WILL SHUT DOWN DURING THE DAY. THERE IS STILL UNCERTAINTY HEADING INTO SUNDAY EVENING/NIGHT PERIOD IN REGARDS TO THE TIMING OF ANY SECONDARY VORTICITY FEATURES ROTATING AROUND THE VORTEX. HOWEVER...IT IS APPEARING MORE LIKELY THAT SUCH A FEATURE WILL PIVOT THROUGH LOWER MICHIGAN OVERNIGHT...GIVING SYNOPTIC SUPPORT TO AN ENVIRONMENT ALREADY SUPPORTIVE OF LAKE EFFECT/ENHANCEMENT. A SOUTHERLY COMPONENT TO THE WESTERLY FLOW WILL MAKE THE SAGINAW RIVER VALLEY THE BEST CHANCE TO SEE ANY ACCUMULATING SNOWS. STRONG...GUSTY WINDS SHOULD MAKE THINGS INTERESTING WITH BLOWING SNOW. BUT AGAIN...NOT EXPECTING ANY SIGNIFICANT ACCUMULATIONS WITH A VEERING WIND PROFILE MAKING STATIONARY BANDS UNLIKELY THIS FAR OFF OF THE LAKE MICHIGAN SHORELINE. COULD SEE ONE INCH SUNDAY NIGHT FOR THE TRI CITIES AND THUMB. HIGH PRESSURE BUILDS INTO THE REGION FOR TUESDAY AND WEDNESDAY ALLOWING FOR SLOWLY MODERATING TEMPERATURES. TEMPERATURES FOR MUCH OF THIS FORECAST WERE LARGELY LEFT AS INHERITED. SIGNIFICANT DIFFERENCES EXIST IN THE MEDIUM RANGE SUITE FOR THE SYSTEM IMPACTING THE GREAT LAKES ON THURSDAY. ATTM...LEFT THE FORECAST ALONE WITH THE HIGH AMOUNT OF UNCERTAINTY. && .MARINE... PERSISTENT SOUTHEAST WINDS WILL GRADUALLY VEER TOWARD THE SOUTH AND BEGIN TO STRENGTHEN THROUGH TONIGHT AS LOW PRESSURE INTENSIFIES AND LIFTS NORTHEAST TOWARD LAKE MICHIGAN. SMALL CRAFT ADVISORY CONDITIONS TODAY ALONG THE NEARSHORE WATERS OF LAKE HURON WILL EXPAND TO INCLUDE LAKE ST CLAIR AND THE MICHIGAN WATERS OF LAKE ERIE TONIGHT. SOUTHWEST TO WEST WINDS WILL FURTHER STRENGTHEN ON SUNDAY AS A STRONG COLD FRONT BLASTS THROUGH. THIS WILL PRODUCE GUSTS TO AT LEAST GALE FORCE ACROSS ALL MARINE AREAS THROUGH SUNDAY NIGHT... BEFORE DIMINISHING ON MONDAY. THE POSSIBILITY EXISTS FOR GUSTS TO BRIEFLY APPROACH LOW END STORM FORCE (UP TO 50 KNOTS)...GIVEN THE STRENGTH OF THE COLD AIR ADVECTION AND POST-FRONTAL PRESSURE RISES... AND WILL CONTINUE TO MONITOR THIS POTENTIAL. && .PREV DISCUSSION...ISSUED 1151 PM EST FRI DEC 21 2007 AVIATION... THE LIGHT EAST-SOUTHEASTERLY WINDS THIS EVENING HAVE ESSENTIALLY MAINTAINED ENOUGH DRY AIR BELOW 1000 FEET SO THAT CEILINGS HAVE PREDOMINATELY REMAINED IN THE MVFR CATEGORY...WITH SURFACE VISIBILITIES BOUNCING BETWEEN MVFR AND VFR. HOWEVER...JUST TO THE WEST OF THE TAF SITES...CEILINGS AND VISIBILITIES DETERIORATE RAPIDLY. THE FLOW ABOVE THE SHALLOW INVERSION IS FORECAST TO STRENGTHEN AND VEER TO THE SOUTH-SOUTHWEST DURING THE COURSE OF THE MORNING. SURFACE DEWPOINTS ARE ALSO FORECAST TO SLOWLY INCH UPWARD THIS MORNING...A TREND THAT IS ALREADY UNDERWAY. BASED ON UPSTREAM CONDITIONS AND THE 00Z NAM AND RUC SOUNDINGS...EXPECT CEILINGS AND VISIBILITIES TO GRADUALLY LOWER DURING THE COURSE OF THE MORNING. BY 11Z...WIDESPREAD IFR AND LIFR CEILINGS AND VISIBILITIES ARE EXPECTED. THERE IS STILL THE POTENTIAL FOR VISIBILITIES BELOW A MILE IN FOG...MAINLY BETWEEN 11Z AND 15Z WHEN SURFACE DEWPOINTS ARE FORECAST TO RISE INTO THE UPPER 30S. INCREASING WINDS IN THE BOUNDARY LAYER SHOULD JUST PROVIDE A SLIGHT IMPROVEMENT TO CEILINGS AND VISIBILITIES THROUGH THE AFTERNOON. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING OUTER SAGINAW BAY...UNTIL 7 AM SUNDAY. GALE WARNING...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...FROM 7 AM SUNDAY TO 10 AM MONDAY. GALE WARNING...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-LHZ464...FROM 10 PM SATURDAY TO 10 AM MONDAY. LAKE ST CLAIR... GALE WARNING...FROM 7 AM SUNDAY TO 10 AM MONDAY. SMALL CRAFT ADVISORY...FROM 10 PM SATURDAY TO 7 AM SUNDAY. MI WATERS OF LAKE ERIE... GALE WARNING...FROM 7 AM SUNDAY TO 10 AM MONDAY. SMALL CRAFT ADVISORY...FROM 10 PM SATURDAY TO 7 AM SUNDAY. && $$ SHORT TERM...MR LONG TERM....CB MARINE.......MR AVIATION.....SC YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1151 PM EST FRI DEC 21 2007 .AVIATION... THE LIGHT EAST-SOUTHEASTERLY WINDS THIS EVENING HAVE ESSENTIALLY MAINTAINED ENOUGH DRY AIR BELOW 1000 FEET SO THAT CEILINGS HAVE PREDOMINATELY REMAINED IN THE MVFR CATEGORY...WITH SURFACE VISIBILITIES BOUNCING BETWEEN MVFR AND VFR. HOWEVER...JUST TO THE WEST OF THE TAF SITES...CEILINGS AND VISIBILITIES DETERIORATE RAPIDLY. THE FLOW ABOVE THE SHALLOW INVERSION IS FORECAST TO STRENGTHEN AND VEER TO THE SOUTH-SOUTHWEST DURING THE COURSE OF THE MORNING. SURFACE DEWPOINTS ARE ALSO FORECAST TO SLOWLY INCH UPWARD THIS MORNING...A TREND THAT IS ALREADY UNDERWAY. BASED ON UPSTREAM CONDITIONS AND THE 00Z NAM AND RUC SOUNDINGS...EXPECT CEILINGS AND VISIBILITIES TO GRADUALLY LOWER DURING THE COURSE OF THE MORNING. BY 11Z...WIDESPREAD IFR AND LIFR CEILINGS AND VISIBILITIES ARE EXPECTED. THERE IS STILL THE POTENTIAL FOR VISIBILITIES BELOW A MILE IN FOG...MAINLY BETWEEN 11Z AND 15Z WHEN SURFACE DEWPOINTS ARE FORECAST TO RISE INTO THE UPPER 30S. INCREASING WINDS IN THE BOUNDARY LAYER SHOULD JUST PROVIDE A SLIGHT IMPROVEMENT TO CEILINGS AND VISIBILITIES THROUGH THE AFTERNOON. && .PREV DISCUSSION...ISSUED 956 PM EST FRI DEC 21 2007 UPDATE... OVERALL THE GOING FORECAST APPEARS IN GOOD SHAPE. RADAR SHOWS GENERALLY LIGHT RETURNS LIFTING NORTHWARD ACROSS THE FORECAST AREA DUE TO MOISTURE ADVECTION WITHIN THE 950-900MB LAYER. SURFACE OBS INDICATE THIS IS MAINLY DRIZZLE. THIS IS SUPPORTED BY THE 00Z DTX SOUNDING WHICH SHOWED MOISTURE CONFINED BELOW 800MB. LIGHT EAST-SOUTHEASTERLY SURFACE WINDS HAVE HELPED KEEP VISIBILITIES MAINLY ABOVE 3 MILES THIS EVENING. HIGHER SURFACE DEWPOINTS HAVE BEEN INCHING UPWARD FROM THE SOUTH...WHICH WILL STILL POSE A THREAT FOR SOME LOWER VISIBILITIES IN FOG...ESPECIALLY TOWARD DAYBREAK. PREV DISCUSSION...ISSUED 313 PM EST FRI DEC 21 2007 SHORT TERM...TONIGHT A SLOW AND STEADY STREAM OF MOISTURE COMING UP FROM THE SOUTH WILL ALLOW FOR LOW STRATUS AND FOG DEVELOPMENT TONIGHT...WITH TEMPERATURES HOLDING STEADY DUE TO THE LOW LEVEL WARM ADVECTION THROUGH THE NIGHT (925 MB TEMPS STARTING AROUND 3 C...WARMING TO 6-7 C TOWARD 12Z SATURDAY PER NAM/GFS BLEND). WITH SLIGHTLY DRIER SOUTHEAST FLOW THROUGH THE NIGHT...A FAIRLY TIGHT PRESSURE GRADIENT...AND MARGINAL SURFACE DEW POINTS (32-35 DEGREES) RIDING OVER THE SNOW PACK...DON`T FORESEE WIDESPREAD DENSE FOG...BUT THERE CERTAINLY LOOKS TO BE POCKETS...ALONG WITH AREAS OF DRIZZLE POSSIBLE WITH SATURATION UP TO 7000 KFT. LONG TERM...SATURDAY THROUGH FRIDAY MODELS HAVE HONED IN ON A BASIC SOLUTION FOR THE STORM SYSTEM THAT WILL DEVELOP OVER THE WESTERN GREAT LAKES LATE SATURDAY/SATURDAY NIGHT AS A MAJOR SOUTHERN STREAM SHORTWAVE LIFTING OUT OF THE SOUTHWEST CONUS PHASES WITH A EQUALLY POTENT NORTHERN STREAM WAVE DROPPING FROM THE CANADIAN PRAIRIES INTO THE NORTHERN PLAINS AND UPPER MIDWEST. THE PREFERRED SOLUTION TAKES A RAPIDLY DEEPENING SURFACE LOW PRESSURE NORTH ALONG LAKE MICHIGAN INTO THE NORTHERN LAKES. IN ADVANCE OF THIS LOW...AN AREA OF RAIN WILL SPREAD OVER LOWER MICHIGAN LATE SATURDAY NIGHT INTO EARLY SUNDAY...WITH A COLD FRONT QUICKLY RACING INTO THE AREA DURING THE EARLY/MID MORNING. WRAPAROUND SNOW SHOWERS WILL THEN PREVAIL FROM SUNDAY INTO SUNDAY NIGHT...PARTICULARLY OVER THE SAGINAW VALLEY...WHERE LAKE EFFECT ENHANCEMENT WILL BE FELT THE MOST. GIVEN THE TIMING OF THE SURFACE FEATURES...MADE MINOR ADJUSTMENTS TO TEMPERATURES SATURDAY NIGHT INTO SUNDAY...WITH LATE EVENING MINIMUM TEMPERATURES EXPECTED LATE SATURDAY BEFORE TEMPERATURES STEADY AND THEN SLOWLY RISE OVERNIGHT IN ADVANCE OF THE APPROACHING COLD FRONT. THE PASSAGE OF THIS FRONT WILL THEN OCCUR FROM 12Z-15Z...SO WILL UP MAXIMUM TEMPERATURES A FEW DEGREES FOR THE EARLY MORNING HOURS WITH TEMPERATURES THEN FALLING SIGNIFICANTLY FROM MID/LATE MORNING ON. SOUTHWEST WINDS IN THE WAKE OF THIS STRONG COLD FRONT WILL ALSO BE VERY STRONG...AND MAY NEED A WIND ADVISORY ON SUNDAY/SUNDAY EVENING IF THE CURRENT MODEL SOLUTION HOLDS. WILL CARRY AT LEAST 40 MPH WIND GUSTS WITH THIS PACKAGE DURING THE DAY SUNDAY. THE COLDER AIRMASS USHERED IN BEHIND THIS STORM SYSTEM HOLDS INTO THE FIRST PART OF NEXT WEEK...WITH ONLY SLOW MODERATION EXPECTED BY MIDWEEK. NO SIGNIFICANT CHANGES TO THE FORECAST ARE NECESSARY FOR THIS TIMEFRAME AS HIGHS EDGE BACK UP FROM THE 20S MONDAY TO MID 30S BY WEDNESDAY. THE NEXT SIGNIFICANT SOUTHERN STREAM SHORTWAVE TO EJECT OUT OF THE SOUTHWEST CONUS IS THEN EXPECTED TO BE IN THIS GENERAL VICINITY BY THURSDAY. MODELS ARE RATHER CONSISTENT IN EJECTING THIS STORM SYSTEM NORTHEAST INTO THE GREAT LAKES DURING THIS TIMEFRAME BUT VARY ENOUGH TO KEEP PRECIPITATION TYPE SOMEWHAT IN QUESTION. PLAN ON MAINTAINING THE CHANCE OF SNOW ATTM FOR CONTINUITY...BUT THIS WILL HAVE TO BE RE-ADDRESSED IF MODELS TREND MORE CONSISTENTLY TO A TRACK FURTHER WEST TO THE VICINITY OF LAKE MICHIGAN...OR WESTERN LOWER MICHIGAN. MARINE... A PREDOMINANT SOUTHEASTERLY WIND MOVING OVER THE LONGER FETCH OF LAKE HURON WILL MAINTAIN SLIGHTLY HIGHER WAVES OVER THE NEARSHORE WATERS NEAR THE TIP OF THE THUMB THROUGH TONIGHT. A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT FOR THESE CONDITIONS. EXPECT THESE CONDITIONS TO EXPAND ON SATURDAY/SATURDAY NIGHT AS SOUTHEAST WINDS INCREASE FURTHER AS LOW PRESSURE TO THE WEST INTENSIFIES. GALES WILL BE POSSIBLE OVER THE OPEN WATERS OF LAKE HURON BY LATE SATURDAY EVENING...AND LIKELY FOR ALL MARINE AREAS ON SUNDAY AS A STRONG COLD FRONT SWEEPS THROUGH THE REGION AROUND THIS LOW AND BRINGS VERY STRONG SOUTHWESTERLY FLOW (PERHAPS GALES UP TO 45 KNOTS AT TIMES). CONDITIONS WILL ONLY SLOWLY IMPROVE LATE SUNDAY NIGHT. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT SANILAC...UNTIL 7 AM SUNDAY. GALE WATCH...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON INCLUDING SAGINAW BAY...FROM 7 AM SUNDAY TO 5 AM MONDAY. SMALL CRAFT ADVISORY...LHZ421-LHZ443...FROM 7 AM SATURDAY TO 7 AM SUNDAY. GALE WATCH...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-LHZ464...FROM 10 PM SATURDAY TO 5 AM MONDAY. LAKE ST CLAIR... GALE WATCH...FROM 7 AM SUNDAY TO 5 AM MONDAY. MI WATERS OF LAKE ERIE... GALE WATCH...FROM 7 AM SUNDAY TO 5 AM MONDAY. && $$ AVIATION.....SC UPDATE.......SC SHORT TERM...SF LONG TERM....DG MARINE.......SF YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 327 AM CST SAT DEC 22 2007 .DISCUSSION... FORECAST CONCERNS SQUARELY ON IMPENDING WINTER STORM THIS WEEKEND. THE FORECAST AREA IS CURRENTLY BISECTED BY INVERTED SURFACE TROUGH...EXTENDING FROM ABOUT AITKIN TO JUST WEST OF THE TWIN CITIES TO ABOUT ALBERT LEA. UNSEASONABLY WARM AND MOIST SURFACE CONDITIONS ARE PRESENT ALONG AND TO THE EAST OF THE TROUGH AXIS...WITH TEMPERATURES/DEW POINTS A FEW DEGREES ABOVE FREEZING. FOG AND PATCHY DRIZZLE/RAIN ARE OCCURRING IN THIS REGION AS A RESULT OF ISENTROPIC LIFT. HAVE EXTENDED THE DENSE FOG ADVISORY FOR AREAS TO THE SOUTH AND EAST OF THE TWIN CITIES THROUGH 15Z...GENERALLY UNTIL COOLER AND DRIER AIR WORKS ITS WAY INTO THE AREA FOLLOWING THE TROUGH PASSAGE. THE FOG THREAT MAY LINGER A LITTLE LONGER IN PARTS OF WISCONSIN...SO HAVE CARRIED A MENTION OF PATCHY DENSE FOG THROUGH 18Z FOR THE 9 WISCONSIN COUNTIES. POWERFUL CLOSED UPPER LOW VERY EVIDENT IN WATER VAPOR SATELLITE OVER SOUTHERN SASKATCHEWAN THIS MORNING...WHICH WILL BE THE CRITICAL PLAYER IN HOW THE WINTER STORM PLAYS OUT THIS WEEKEND. LOW CENTER OVER WESTERN NORTH TEXAS IN THE DETACHED SOUTHERN STREAM WILL RACE NORTHEASTWARD AS THE UPPER JET MOVES INTO THE OHIO VALLEY. AT THE SAME TIME...THE UPPER LOW DROPS SOUTHEASTWARD AND EVENTUALLY PHASES WITH THE SOUTHERN STREAM UPPER TROUGH. AS THIS OCCURS LATE TONIGHT...THE SURFACE LOW DEEPENS QUITE NICELY OVER LAKE MICHIGAN. A STRONG FRONTOGENETIC RESPONSE...AND UPPER LEVEL Q-VECTOR CONVERGENCE...ARE SEEN OVER THE WESTERN WISCONSIN COUNTIES...ESPECIALLY IN THE OVERNIGHT HOURS TONIGHT. EAST/WEST CROSS SECTIONS THROUGH THIS REGION SHOW A SMALL AREA OF NEGATIVE EPV ABOVE THE REGION OF MAXIMUM UPWARD MOTION IN A FAVORABLE DENDRITIC GROWTH ZONE OVER PRIMARILY NORTH CENTRAL WISCONSIN...ALTHOUGH THE WESTERN EDGE OF THIS FAVORED AREA DOES HANG OVER THE FAR EASTERN EDGE OF THE FORECAST AREA. THE FAVORED TIME APPEARS TO BE LATE SATURDAY NIGHT THROUGH SUNDAY MORNING. THE SNOW WILL CONTINUE IN THIS AREA...AND SOLIDLY REENTER MUCH OF THE REMAINDER OF THE AREA FROM THE NORTH...AS THE WRAP AROUND MOISTURE/CYCLONIC CURVATURE RESULT IN ADDITIONAL SNOW ACTIVITY. IN ALL...INGREDIENTS APPEAR TO FAVOR STORM TOTAL AMOUNTS AROUND 6 INCHES TO THE EAST OF A RICE LAKE TO DURAND LINE...WITH A QUICK DROP OFF TO THE WEST OF THIS LINE. THE DEEPENING LOW WILL ALSO CREATE HAVOC WITH THE WINDS AND RESULTANT BLOWING SNOW POTENTIAL. WITH CONFIDENCE NOT TERRIBLY HIGH THAT THE HIGHER SNOW TOTALS WILL NOT BE CONFINED TO AREAS EAST OF THE FORECAST AREA...WE HAVE CONTINUED THE WINTER STORM WATCH...BUT SLID THE EFFECTIVE TIME BACK 6 HOURS...RUNNING FROM 00Z TONIGHT THROUGH 00Z MONDAY. TEMPERATURES ALSO AN ISSUE WITH SUCH A CONTRAST ACROSS THE FORECAST AREA AT THIS TIME. MANY AREAS WILL LIKELY SEE THEIR HIGHS FOR TODAY DURING THE MORNING HOURS...SO HAVE PAINTED A NON-DIURNAL TEMPERATURE TREND IN THE HOURLY TEMPERATURE FORECAST. THINGS SHOULD DROP LIKE A ROCK LATE THIS EVENING OVER WESTERN PARTS OF THE AREA UNDERNEATH THE DRY SLOT. QUITE A TRICKY FORECAST...WITH CLOUDS EXPECTED TO PREVENT A TOTAL PLUMMET IN TEMPERATURES. SURFACE RIDGE MOVES ACROSS THE AREA EARLY IN THE UPCOMING WEEK...WHICH WILL BRING MUCH COOLER TEMPERATURES THAN WE HAVE SEEN OVER THE LAST WEEK OR SO...AS WELL AS DRY AND LESS FOGGY WEATHER. ANOTHER UPPER LEVEL TROUGH APPROACHES FOR THE MIDDLE OF THE WEEK...BRINGING INCREASED POTENTIAL FOR SNOW ONCE AGAIN. WARM AIR AHEAD OF THE TROUGH WILL BRING TEMPERATURES UP A TAD FROM THE POST CURRENT SYSTEM LOWS TO OCCUR SUNDAY. && .AVIATION.../06Z TAF ISSUANCE/ CHALLENGE WITH AVIATION REMAINS PRECIP TIMING AND TYPE THROUGH THE NEXT SIX HOURS...THEN SNOWFALL INTENSITY AT WRN WI TAF SITES DURING THE DAY TODAY. VLIFR CIGS AND VISBYS TO CONTINUE ACROSS THE ENTIRE AREA THROUGH THIS MORNING. OBSERVATIONS AND RADAR SIGNATURES INDICATING PRECIP TYPE SHOULD BE ALL SNOW AT AXN NOW. THE BAND OVER I-29 SHOULD WEAKEN IN INTENSITY AS IT SHIFTS OVER AXN OVERNIGHT. LOW TO MID LEVEL WARM AIR ADVECTION CURRENTLY LEADING TO SOME DRIZZLE OVER THE AREA WITH THE 13KM RUC MODEL BRINGING MORE INTENSE ADVECTION UP BETWEEN 09 AND 12Z. CURRENT TAMDAR SOUNDINGS FROM DEPARTING AND ASCENDING FLIGHTS AT MSP HAVE THE WARM CORE AT 4C. THIS WOULD POINT TOWARDS -RA OR POSSIBLY -FZRA IN THE 09 TO 12Z TIME AT MSP IF THE TEMPS DROP A COUPLE DEGREES IN THE NEXT FEW HOURS. HOWEVER...THE WARM LAYER ALOFT IS DRY INDICATING EVAPORATIVE COOLING COULD LEAD TO A QUICK TRANSITION TO SNOW. HAVE TEMPOED THE TWO PRECIP TYPES FOR NOW...BUT CONFIDENCE IS HIGH THAT AFTER 12Z SNOW SHOULD BE THE DOMINANT PRECIP TYPE AT MSP. A LITTLE LATER IS ON TAP FOR THE WI TAF SITES AS COLD AIR SHIFTS WEST. AS SRN STREAM LOW PRESSURE SYSTEM LIFTS NORTH NORTHEAST INTO THE LOWER GREAT LAKES...SNOW WILL BECOME MODERATE AT TIMES DURING THE AFTN AT EAU. WINDS ACROSS MN TAF SITES WILL BE INCREASING DURING THE AFTN LEADING TO SOME BLOWING SNOW KEEPING VISBYS LOW DESPITE SNOWFALL POTENTIAL SHIFTING EAST. WINDS MAY GUST UP TO 30 KTS AT THESE LOCALES. BEYOND TAF PERIOD...STRONG WEST TO NORTHWEST WINDS WILL CONTINUE SATURDAY NIGHT AND ESPECIALLY ON SUNDAY. GUSTS TO OVER 30 KTS WITH SOME LINGERING SNOW IS CURRENTLY EXPECTED. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 6 AM CST THIS MORNING FOR CHIPPEWA-DOUGLAS-LAC QUI PARLE-POPE-STEVENS-SWIFT-TODD-YELLOW MEDICINE. DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR BLUE EARTH- CARVER-DAKOTA-FARIBAULT-FREEBORN-GOODHUE-HENNEPIN-LE SUEUR- RAMSEY-RICE-SCOTT-STEELE-WASECA-WASHINGTON. WI...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY AFTERNOON FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-RUSK. && $$ KAT/MTF mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1123 PM CST FRI DEC 21 2007 .DISCUSSION... 12Z NAM/GFS AND ECMWF ALL VERY SIMILAR IN BRINGING NORTH STREAM CLOSED LOW OVER ALBERTA TO MN BY SUNDAY MORNING WITH THE SOUTHERN STREAM LOW...CURRENTLY OVER THE FOUR CORNERS...PIVOTING UNDERNEATH AND REACHING THE LOWER GREAT LAKES. COLD FRONT TO MOVE ACROSS MUCH OF THE MN CWA TONIGHT AND SLOWLY ACROSS WI ON SATURDAY. A SURFACE LOW IS PROGGED TO RIDE NORTHEAST ALONG THE FRONT AND REACH NORTHERN LAKE MICHIGAN BY SUNDAY MORNING. ALL THREE OF THE MODELS REACHED THE SAME LOCATION AND WERE WITHIN ONE MILLIBAR OF EACH OTHER. QUITE A FEAT 48 HOURS OUT. IN THE MEAN TIME...PLENTY OF WEATHER ELEMENTS FOR THE CWA THROUGH SUNDAY. DENSE FOG REMAINS A PROBLEM TONIGHT OVER EASTERN AND SOUTHERN AREAS OF THE CWA WITH TEMP/DP`S LOCKED IN THE LOWER TO MIDDLE 30S. WE EXTENDED THE DENSE FOG ADVISORY THROUGH 12Z SATURDAY. WE RECENTLY ISSUED A WINTER WEATHER ADVISORY FOR WEST CENTRAL AREAS OF MINNESOTA FROM THIS EVENING THROUGH NOON SATURDAY. RAIN AND FREEZING RAIN DEVELOPING AHEAD OF THE APPROACHING FRONT THIS EVENING THEN TRANSITIONING TO SNOW QUICKLY AFTER MIDNIGHT. THE WIND WILL PICK UP OVERNIGHT AND CONTINUE THROUGH THE MORNING WITH SOME BLOWING AND DRIFTING SNOW. LATER SHIFTS MAY NEED TO EXTEND OR ISSUE A NEW ADVISORY TO THE TWIN CITIES FOR SNOW AND BLOWING SNOW ON SATURDAY. OVERALL..STILL THINK 2 TO 3 INCHES WILL COVER THE SNOW ACCUMULATION FOR THE MN CWA TONIGHT AND SATURDAY WITH THE 3 INCH AMOUNT FROM CAMBRIDGE THROUGH THE TWIN CITIES TO ALBERT LEA. MAINTAINED THE WINTER STORM WATCH FOR PORTIONS OF WEST CENTRAL WI FROM NOON SATURDAY TO NOON SUNDAY. THE FAR EASTERN CWA IS RIGHT ON THE EDGE OF THE WAA AND ISENTROPIC LIFT SATURDAY AFTERNOON AND EVENING. THE BEST 600-700MB FWF IS TO THE SOUTH AND EAST OF THE WI CWA AND NOT MUCH HELP. MIXING RATIOS AROUND 3 G/KG WITH A PERIOD OF ABOUT 5 HOURS WHERE THE OMEGA IS MAXIMIZED IN THE BEST DENDRITIC GROWTH ZONE. THE GRIDS ARE LOADED WITH AROUND 6 INCHES OF ACCUMULATION IN THE WATCH AREA...ESPECIALLY NEAR LADYSMITH...WHERE MID LEVEL DEFORMATION IS BETTER LATER SATURDAY NIGHT AS THE SYSTEM SHOWS SIGNS OF NEGATIVE TILT. AS A RESULT OF THE LOW STRENGTHENING TO OUR EAST LATE SATURDAY INTO SUNDAY...IT WILL BE QUITE WINDY OVER MUCH OF THE REGION ON SUNDAY. INDICATIONS OF A 12 MB GRADIENT ACROSS THE MN CWA WITH 30 KNOT WINDS POSSIBLE. THIS SETS UP SEVERAL PROBLEMS FOR SUNDAY. COULD THERE BE CONSIDERABLE BLOWING SNOW AND LOW VISIBILITY OVER WEST CENTRAL AND SOUTHERN MN? HAVE INCLUDED THE STRONG WINDS AND BLOWING SNOW FOR NOW. THINGS QUIET DOWN FOR A BIT MONDAY AND TUESDAY AS HIGH PRESSURE FINALLY BUILDS IN. BROUGHT SOME SNOW BACK IN LATER IN THE WEEK PER THE ECMWF WHICH WAS HIGHLY FAVORED (PREEPD). && .AVIATION.../06Z TAF ISSUANCE/ CHALLENGE WITH AVIATION REMAINS PRECIP TIMING AND TYPE THROUGH THE NEXT SIX HOURS...THEN SNOWFALL INTENSITY AT WRN WI TAF SITES DURING THE DAY TODAY. VLIFR CIGS AND VISBYS TO CONTINUE ACROSS THE ENTIRE AREA THROUGH THIS MORNING. OBSERVATIONS AND RADAR SIGNATURES INDICATING PRECIP TYPE SHOULD BE ALL SNOW AT AXN NOW. THE BAND OVER I-29 SHOULD WEAKEN IN INTENSITY AS IT SHIFTS OVER AXN OVERNIGHT. LOW TO MID LEVEL WARM AIR ADVECTION CURRENTLY LEADING TO SOME DRIZZLE OVER THE AREA WITH THE 13KM RUC MODEL BRINGING MORE INTENSE ADVECTION UP BETWEEN 09 AND 12Z. CURRENT TAMDAR SOUNDINGS FROM DEPARTING AND ASCENDING FLIGHTS AT MSP HAVE THE WARM CORE AT 4C. THIS WOULD POINT TOWARDS -RA OR POSSIBLY -FZRA IN THE 09 TO 12Z TIME AT MSP IF THE TEMPS DROP A COUPLE DEGREES IN THE NEXT FEW HOURS. HOWEVER...THE WARM LAYER ALOFT IS DRY INDICATING EVAPORATIVE COOLING COULD LEAD TO A QUICK TRANSITION TO SNOW. HAVE TEMPOED THE TWO PRECIP TYPES FOR NOW...BUT CONFIDENCE IS HIGH THAT AFTER 12Z SNOW SHOULD BE THE DOMINANT PRECIP TYPE AT MSP. A LITTLE LATER IS ON TAP FOR THE WI TAF SITES AS COLD AIR SHIFTS WEST. AS SRN STREAM LOW PRESSURE SYSTEM LIFTS NORTH NORTHEAST INTO THE LOWER GREAT LAKES...SNOW WILL BECOME MODERATE AT TIMES DURING THE AFTN AT EAU. WINDS ACROSS MN TAF SITES WILL BE INCREASING DURING THE AFTN LEADING TO SOME BLOWING SNOW KEEPING VISBYS LOW DESPITE SNOWFALL POTENTIAL SHIFTING EAST. WINDS MAY GUST UP TO 30 KTS AT THESE LOCALES. BEYOND TAF PERIOD...STRONG WEST TO NORTHWEST WINDS WILL CONTINUE SATURDAY NIGHT AND ESPECIALLY ON SUNDAY. GUSTS TO OVER 30 KTS WITH SOME LINGERING SNOW IS CURRENTLY EXPECTED. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 6 AM CST SATURDAY FOR BLUE EARTH-BROWN- CARVER-DAKOTA-FARIBAULT-FREEBORN-GOODHUE-HENNEPIN-LE SUEUR- MARTIN-MCLEOD-MEEKER-NICOLLET-RAMSEY-REDWOOD-RENVILLE-RICE- SCOTT-SIBLEY-STEELE-WASECA-WASHINGTON-WATONWAN-WRIGHT. WINTER WEATHER ADVISORY UNTIL 12 PM CST SATURDAY FOR CHIPPEWA- DOUGLAS-LAC QUI PARLE-POPE-STEVENS-SWIFT-TODD-YELLOW MEDICINE. WI...DENSE FOG ADVISORY UNTIL 6 AM CST SATURDAY FOR BARRON-CHIPPEWA- DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY MORNING FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-RUSK. && $$ RAH/MTF mn AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE ALBUQUERQUE NM 259 AM MST SAT DEC 22 2007 .DISCUSSION... LATEST WATER VAPOR LOOP EARLY THIS MORNING SHOWS AN IMPRESSIVE UPPER LOW PRESSURE SYSTEM OVER THE NE PLAINS WITH A DISTINCT COMMA HEAD AND DRY SLOT FEATURE. RADAR TRENDS SHOW SNOW IS HOLDING STEADY OVER THE NORTHERN MTNS WITH CLEARING FARTHER TO THE WEST AND SOUTH...AND HEAVY SNOW ALONG THE INTERSTATE 40 CORRIDOR FROM SANTA ROSA EAST TO KTCC. WINDS ARE ALSO HOWELING OUT OF THE NORTH AT 30 TO 40 MPH CREATING VERY HAZARDOUS TRAVEL CONDITIONS IN MUCH OF THE NE PART OF THE CWA NORTH OF A FORT SUMNER TO CLOVIS LINE. WILL INCLUDE ADV LEVEL WINDS WITH THE WINTER HAZARD PRODUCTS. IR SAT SHOWS CLEARING OVER THE WESTERN HALF OF THE STATE WITH THE BACK EDGE OF THE COMMA HEAD NEARLY STATIONARY FROM CUBA SE TO KSAF. WILL CANCEL WARNINGS/ADVISORIES THAT WERE TO EXPIRE AT 600 AM. WARNINGS WILL CONTINUE IN THE EAST WITH ANOTHER 1 TO 3 INCHES ESPECIALLY ALONG INTERSTATE 40 NEAR KTCC. ADVISORY TO THE SOUTH WILL ALSO STAY INTACT MAINLY FOR THE BLOWING SNOW HAZARD APPROACHING FROM THE NORTH. EXPECT CLEARING IN THE EAST AFTER 18Z AS INDICATED BY RUC13 SO DAY SHIFT MAY CONSIDER DROPPING ADVISORY IN THE SE AT THAT TIME. THINK WARNINGS WILL CONTINUE UNTIL 600 PM IN THE NE DUE TO EXTREMELY HAZARDOUS TRAVEL CONDITIONS. VERY COLD NIGHT EXPECTED ACROSS THE CWA...ESPECIALLY IN AREAS WITH SNOWPACK. SUNDAY WILL BE VERY NICE EARLY IN THE DAY WITH INCREASING CLOUDS OVER THE NORTH. NEXT SYSTEM WILL MOVE QUICKLY SE ACROSS THE SANGRES AND NE PLAINS SUNDAY NIGHT WITH ADVISORY LEVEL SNOWS POSSIBLE OVER THE SANGRES SIMPLY DUE TO VERY HIGH SNOW RATIOS. COLD WEATHER CONTINUES MONDAY ACROSS THE REGION DESPITE MOSTLY SUNNY SKIES. 00Z MODELS ARE BEGINNING TO CHANGE THEIR TUNE ON WEATHER PATTERN FOR CHRISTMAS INTO THE NEW YEAR WITH SYSTEMS PASSING FARTHER TO THE NORTH THAN PREVIOUS RUNS. THIS STILL MEANS POSSIBLE SIGNIFICANT WINTER STORMS FOR THE NORTHERN MOUNTAINS AND NE PLAINS HOWEVER THE SOUTH AND WEST MAY ESCAPE WITH GLANCING BLOWS. TWEAKED EXTENDED GRIDS TO ADJUST POPS SLIGHTLY FARTHER NE HOWEVER WILL WAIT FOR A MORE CONSISTENT TREND TO APPEAR. GUYER && .AVIATION... OCCASIONAL IFR CONDITIONS IN SNOW...BLOWING SNOW AND FREEZING FOG TO PERSIST FROM KSAF NORTHEAST AND EASTWARD TO THE TEXAS AND COLORADO BORDER THROUGH MIDDAY. LOCAL MOUNTAIN OBSCURATION ALONG AND WEST OF THE RIO GRANDE VALLEY EXPECTED THROUGH MIDDAY ALSO. NORTHWEST SURFACE WIND TO INCREASE AT KFMN...WITH NORTH TO NORTHWEST WINDS GUSTING TO AROUND 35 OR 40 KTS ALONG AND EAST OF CENTRAL MOUNTAIN CHAIN. WINDS SHOULD TAPER OFF LATE AFTERNOON. NEXT AVIATION DISCUSSION SCHEDULED FOR 22Z. && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 35 14 38 16 / 0 0 5 5 GALLUP.......................... 35 6 40 6 / 0 0 0 0 GRANTS.......................... 35 7 41 9 / 5 0 0 0 GLENWOOD........................ 44 21 52 23 / 0 0 0 0 CHAMA........................... 29 -4 32 -6 / 5 0 10 20 LOS ALAMOS...................... 34 8 37 5 / 10 0 5 5 RED RIVER....................... 20 2 31 5 / 20 0 10 40 TAOS............................ 33 4 38 6 / 20 0 5 20 SANTA FE........................ 32 11 36 8 / 20 0 5 5 SANTA FE AIRPORT................ 36 12 39 16 / 20 0 5 5 ESPANOLA........................ 40 10 42 17 / 20 0 5 5 ALBUQUERQUE HEIGHTS............. 42 20 43 24 / 10 0 0 0 ALBUQUERQUE VALLEY.............. 44 16 45 20 / 10 0 0 0 ALBUQUERQUE FOOTHILLS........... 42 16 41 20 / 20 0 0 0 ALBUQUERQUE WEST MESA........... 43 18 44 23 / 10 0 0 0 SOCORRO......................... 45 19 48 24 / 5 0 0 0 SANDIA PARK/CEDAR CREST......... 37 12 38 14 / 20 0 5 0 MORIARTY/ESTANCIA............... 37 17 40 19 / 30 0 0 0 CARRIZOZO....................... 39 20 42 21 / 20 0 0 0 RUIDOSO......................... 32 17 40 17 / 20 0 0 0 RATON........................... 32 8 40 11 / 30 0 5 20 LAS VEGAS....................... 31 14 38 13 / 50 0 5 20 ROY............................. 35 16 37 15 / 60 0 5 20 CLAYTON......................... 33 14 40 18 / 60 0 0 20 SANTA ROSA...................... 42 16 43 20 / 60 0 0 5 TUCUMCARI....................... 38 13 42 18 / 60 0 0 20 FORT SUMNER..................... 43 19 50 20 / 60 0 0 0 CLOVIS.......................... 37 19 48 21 / 70 0 0 0 PORTALES........................ 39 19 48 20 / 70 0 0 0 ROSWELL......................... 48 22 52 25 / 30 0 0 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 6 PM MST THIS AFTERNOON FOR THE FOLLOWING ZONES...NMZ002>007-010>013. WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS AFTERNOON FOR THE FOLLOWING ZONES...NMZ016>021-026. HIGH WIND WARNING UNTIL 9 AM MST THIS MORNING FOR THE FOLLOWING ZONES...NMZ005. && $$ GUYER/99 CORRECTION TO ADD HIGH WIND WARNING TO ZONE 5 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 615 AM CST SAT DEC 22 2007 .UPDATED FOR TO DROP PORTIONS OF DENSE FOG ADVISORY AND TO ADD 12Z AVIATION DISCUSSION... WINDS SHIFTING NORTHWESTERLY EARLIER THAN PREVIOUSLY THOUGHT ALLOWING VSBYS TO IMPROVE ACROSS MUCH OF THE CWA SO HAVE CANCELLED WESTERN/SOUTHERN PORTIONS OF THE ADVY. AREAS ACROSS THE EAST CENTRAL CWA REMAIN BENEATH THE DENSE FOG...SO HAVE ADVY GOING UNTIL 15Z FOR THAT AREA. WILL MONITOR AS WINDS SHIFT...ADVY MAY BE ABLE TO BE DROPPED EARLY. .SYNOPSIS... IMPENDING SYSTEM CURRENTLY PULLING OUT OF ROCKIES WITH SEVERAL SHRT WVS ROTATING AROUND UPPER LOW NEAR NM/CO BORDER. ANOTHER WEAKER WV NOTED INTO NWRN IA TRYING TO SPREAD LGT PCPN INTO THAT AREA. VERY STRONG QG FORCING IN IMMEDIATE VICINITY OF THIS COMPACT LOW BUT HAS YET TO SPREAD TOO FAR INTO NE OR KS WITH SIGNIFICANT PCPN STILL RELEGATED TO ERN CO/WRN KS. NRN STREAM SHRT WV OVER SERN SASKATCHEWAN WITH ASSOCIATED FORCING NOT A FACTOR FOR THE TIME BEING. 08Z SFC ANLYS PLACES FRONTAL BOUNDARY FROM JUST W OF TWIN CITIES TO SUBTLE LOW JUST N OF LWD THEN TRAILING INTO OK. BROAD PRES RISES NOTED THROUGHOUT PLAINS WITH VERY DRY UPSTREAM AIRMASS. && .DISCUSSION... OBVIOUS PRIMARY CONCERN WILL BE IMPACT OF WEEKEND STORM...BUT WILL HAVE TO DEAL WITH DENSE FOG ADVY FIRST. WITH INCREASING NWLY WINDS ALREADY TO ICL-CIN-EST LINE WITH CFP HAVE SHIFTED ADVY EWD AND IS NOW IN EFFECT E OF THESE AREAS TIL 15Z AND BASICALLY I35 CORRIDOR EWD TIL 18Z. TEMPS SHOULD BE FALLING SO FORECAST HIGHS ARE VERY CLOSE TO CURRENT READINGS. REGARDING THE WINTER STORM...NAM SEEMED TO INITIALIZE JUST A TAD BIT BETTER AT 00Z WITH SLIGHTLY DEEPER FEATURES THROUGH DEPTH OF ATMOSPHERE. HOWEVER WILL BE FAVORING GFS AS WELL AS 00Z SPC WRF AND THEIR MORE WLY QPF SOLUTION. CONFIDENCE NOT THE GREATEST WITH 00Z ECMWF AND 06Z NAM STILL GOING FARTHER E. HOWEVER GFS...ALONG WITH 06Z RUC...SEEM TO HAVE BETTER HANDLE ON CURRENT WX AFTER 06Z AND EXTRAPOLATION OF DEVELOPING DEF ZN INTO IA.. THIS WOULD SUGGEST THAT FARTHER W SOLUTION THE WAY TO GO WITH HEAVIER SNOWS BACK INTO DSM METRO AND POINTS S AND E. MODEL BIASES OFTEN PLACE HEAVIER ACCUMS TOO FAR SE...WITH THE NAM OFTEN SEEMING TO BE SHADING HIGHER QPF AMOUNTS TOO CLOSE TO CONVECTION AND NOT EMPHASIZING DEF ZN ADEQUATELY. MUCH LIKE YESTERDAY...FORCING IN DENDRITIC LAYER SEEMS TO BE IN H5/H6 LAYER OR AROUND 300/305K ISENT SFCS. UVM IN THESE AREAS OF CONCERN SPREAD NEWD INTO IA BY 18Z BUILDING ON SE-NE ORIENTED BAND ALREADY DEVELOPING ON RADAR. ALTHOUGH SOME THETA-E ADVECTION AND FRONTOGENETICAL FORCING IS NOTED...BRUNT OF UVM SEEMS TO BE DRIVEN BY DPVA AS SHRT WV LIFTS OUT. THIS STILL RESULTS IN STRONG OVERALL QG FORCING INTO THE AFTN BEFORE REACHING FAR ERN PORTIONS THIS EVE. SERN FRINGE OF THIS AREA WILL SEE THETA-E LAPSE RATES AND EPV GOING NEGATIVE SO EXPECT STATIC STABILITY WILL BE QUITE LOW. LIGHTNING HAS ALREADY BEEN OBSERVED NEAR LOW CORE AND WOULD NOT BE SURPRISED TO BRIEFLY SEE SOME CONVECTIVE ELEMENTS BEFORE STABILITY MIN MOVES INTO IL THIS EVE. CURRENT SNOW TOTALS VARY FROM 4-7 INCHES IN THE WARNING...BUT COULD SEE ISOLD HIGHER AMOUNTS IF CONVECTION PANS OUT. THIS CONVECTION AND POTENTIAL LATENT HEAT RELEASE MAY BE ANOTHER REASON TO FAVOR MORE NWLY GFS SOLUTION WITH LOWER PRESSURES INTO COLDER AIR. ALSO JUST NOTICED 06Z NAM HAS STRONG DENDRITIC FORCING BACK INTO ALO-OTM CORRIDOR THROUGH 06Z BUT QPF NOT FAR ENOUGH WWD TO REFLECT THAT. ANOTHER REASON TO FAVOR 00Z GFS. HAVE SWITCHED PREVIOUS WATCH TO WINTER STORM WARNING AND ADVY. WRNG IS ESSENTIALLY WHERE SNOW AMOUNTS ARE EXPECTED TO BE 4 INCHES PLUS. THIS FUDGES CRITERIA SOMEWHAT...BUT BLENDS WELL INTO ADJACENT HEADLINES AND AM NOT GOING TO WORRY ABOUT DETAILS CONSIDERING THE BLOWING SNOW POTENTIAL. JUST TO THE NW...SNOW AND BLOWING SNOW ADVY IN EFFECT WHERE AMOUNTS SHOULD REACH 1-4". SFC PRESSURES GO FROM JUST ABOVE 1000MB THIS EVE TO 985 OR LESS BY MIDDAY SUN WHEN LOW REACHES GREAT LAKES. THIS WILL REALLY CRANK THE WINDS UP WITH IMPRESSIVE ISALLOBARIC COMPONENT AND PRES GRADIENT LIKELY PUSHING WINDS INTO BLIZZARD WARNING POTENTIAL ERN HALF. NRN IL LOOKS TO BE HIT ESPECIALLY HARD. THIS WOULD BE LATE 2ND PERIOD SO WILL LEAVE THAT UPGRADE FOR LATER SHIFTS BUT WOULD NOT BE SURPRISED IF IT IS REACHED EARLY SUN WITH PROJECTED GUSTS INTO THE LOWER/MIDDLE 30KTS. EXPECT PLENTY OF WRAP AROUND STRATUS AND POTENTIALLY FLURRIES CONTINUING LATER SUN AND SUN NIGHT. NO CHANGES TO LATER PERIODS. CONSIDERING STRENGTH OF CAA...SNOW COVER AND PERSISTENT LOW CLOUDS HAVE GONE JUST BELOW COOLEST GUIDANCE FOR HIGHS SUN. DO NOT SEE MUCH THERMAL CHANGE SUN NIGHT WITH MORE STRATUS AND WINDS KEEPING THINGS MIXED SO ONLY WENT WITH SEVERAL DEGREE DIURNAL DROP TOWARD HIGHER END OF GUIDANCE. LOW LEVEL MOISTURE LINGERS INTO MON AND WITH INVERSION STILL IN PLACE AROUND SOLAR MIN DO NOT SEE MUCH HOPE FOR REBOUND. HAVE CLIPPED CURRENT MON FORECAST QUITE A BIT NOW GOING AT LEAST A CATEGORY BELOW COOLEST GUIDANCE...WHICH IS A BLEND OF RAW TEMPS. MAY HAVE TO GO EVEN FURTHER IN UPCOMING PACKAGES. && .AVIATION...22/12Z VSBYS STARTING TO IMPROVE AT ALL TAF SITES WITH THE EXCEPTION OF KALO...AS A COLD FRONT PROGRESSES THROUGH THE CWA. WINDS HAVE TAKEN ON SOME SORT OF WESTERLY COMPONENT...AND EXPECT ALL TERMINALS TO HAVE NORTHWEST WINDS BY 15Z. STILL EXPECTING FAIRLY DECENT SYSTEM TO IMPACT THE REGION TODAY...WITH PRECIPITATION MOVING INTO KFOD...MCW...AND KALO BY 18Z...AND INTO KDSM AND KOTM THROUGH EARLY AFTERNOON. PRECIPITATION MAY BEGIN AS RAIN...BUT WILL QUICKLY CHANGEOVER TO SNOW THIS MORNING AT KFOD...KMCW...AND KALO. KDSM WILL TURN TO SNOW BY EARLY AFTERNOON...AND KOTM BY LATE AFTERNOON. PRECIPITATION MAY BE HEAVY AT TIMES ACROSS THE SOUTHERN TAF SITES...WITH WINDS PICKING UP INTO THE AFTERNOON/OVERNIGHT HOURS. THEREFORE EXPECT IMPACTS FROM BLOWING SNOW AT MOST TERMINAL LOCATIONS. HAVE ONLY GONE WITH 1SM VSBYS FROM BLSN AT THIS TIME...BUT EXPECT AS SYSTEM RAMPS UP VSBYS LESS THAN A MILE WILL BE MORE PREVALENT. && .DMX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVY FOR EAST CENTRAL PORTION OF CWA THROUGH 15Z. WINTER STORM WARNING BASICALLY ALONG AND EAST OF CORNING-AMES-HAMPTON LINE 18Z-12Z. SNOW AND BLOWING SNOW ADVY BASICALLY ALONG AND EAST OF DNS-CIN-AXA LINE BLENDING INTO WARNING...15Z-12Z. && $$ SMALL/ALBRECHT ia AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 700 AM EST SAT DEC 22 2007 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE POTENTIAL FOR AND FOG THIS AFTERNOON... .SYNOPSIS...WATER VAPOR IMAGERY AND RUC SHOWING TWO CLOSED LOW EMBEDDED IN A LONGWAVE TROUGH OVER MID SECTION OF CONUS. ONE OF THE LOWS IS OVER NORTH CENTRAL NORTH DAKOTA AND THE OTHER IS OVER THE TEXAS PANHANDLE. WEAK SHORTWAVES BEING EJECTED OUT OF THIS SYSTEM ARE OVER IOWA AND OVER LAKE SUPERIOR. SURFACE ANALYSIS DEPICTS A LOW OVER EASTERN OKLAHOMA AND A LOW OVER WESTERN ONTARIO WITH A COLD FRONT EXTENDING BETWEEN THE TWO LOWS. A LARGE HIGH OVER MIDDLE HIGH PLAINS IS PUSHING THE FRONTAL SYSTEM EAST. THE FLOW AHEAD OF THE FRONTAL SYSTEM IS DRAWING DEEP MOISTURE AND WARM AIR FROM THE GULF NORTHWARD INTO THE UPPER GREAT LAKES REGION. ISENTROPIC ASCENT AHEAD OF THE SYSTEM CONTINUES TO PRODUCE RAINS OVER THE AREA. KMQT-88D SHOWING SEVERAL BANDS OF RAIN MOVING THROUGH THE FORECAST AREA. LOW LEVEL MOISTURE AND SURFACE BASED INVERSION AND LIGHT WINDS HAVE PRODUCE CONSIDERABLE FOG AROUND THE AREA THIS MORNING. .SHORT TERM...TODAY... THE MID LEVEL LOW OVER NORTH DAKOTA WILL SHIFT TO EAST CENTRAL NORTH DAKOTA TODAY...WHILE THE TEXAS LOW LIFTS NORTHEAST INTO SOUTHEAST KANSAS. THE ONTARIO SURFACE LOW WILL SETTLE SOUTH INTO WESTERN LAKE SUPERIOR WHILE THE OKLAHOMA LOW MOVES INTO SOUTHERN MISSOURI. THE FRONTAL SYSTEM WILL CONTINUE TO DRAW MORE DEEP MOISTURE INTO THE REGION AHEAD OF IT. AREAS OF RAIN WILL CONTINUE OVER THE AREA TODAY AS WEAK SHORTWAVES SHIFT INTO THE AREA AND ISENTROPIC ASCENT PREVAIL OVER THE AREA THIS AFTERNOON. LONG TERM...TONIGHT AND LATER... FOR TNGT...NAM/GFS IN EXCELLENT AGREEMENT SHOWING DETAILS OF PHASING BRANCHES...WITH RDPLY DEEPENING LO PRES MOVING TO NEAR GRB BY 12Z SUN. INCRSG UPR DIFFLUENCE/H5 HGT FALLS/DEEP LYR QVECTOR CNVGC TO THE NE OF DVLPG NEGATIVELY TILTED CUTOFF LO AT H5 JUST TO THE SW OF MPX ESPECIALLY AFT 06Z WL SUPPORT INCRSGLY WDSPRD PCPN. TRACK OF SFC LO WL DRAW ENUF WARM AIR INTO THE ERN/NCNTRL FA TO MAINTAIN JUST RA... BUT OVER THE W THE COMBINATION OF INTENSE UVV/DYNAMIC COOLING AND INFLUX OF LLVL COLD AIR WL CAUSE THE PCPN TO BE SN OR CHG TO SN. USING NAM FCST WBZ HGT OF 1500FT/H925-85 THKNS OF 676M AS A GUIDE... LOOK FOR THE RA/SN LINE TO BE FM CMX-HURON MNTS-CRYSTAL FALLS OR SO BY 12Z SUN ON THE COLD SIDE OF THE H85 LO TRACK. ON SUN...SFC LO PROGGED TO MOVE TO SLOWLY TO ARND SCNTRL LK SUP BY LATE IN THE DAY AS UPR LO SLIDES INTO THE CNTRL GRT LKS...SUPPORTING 12HR H5 HGT FALLS UP TO 150M. PCPN WL GRDLY CHG TO SN WITH DYNAMIC COOLING...BUT WARM LYR ALF/TROWAL FEATURE WL RETARD CHGOVER NEAR LK SUP OVER THE NCNTRL...ESPECIALLY WITH N FLOW OFF THE WARM LK WATERS. IN FACT...THE PCPN MAY CHG TO SN FASTER OVER THE E AND NEAR LK MI THAN AT THE CITY OF MQT. OTRW...ARRIVAL OF HIER SPECIFIC HUMIDITY FM THE NNE TO THE W OF LO WL ENHANCE PCPN RATES ESPECIALLY WHERE LLVL NNE FLOW UPSLOPES AND WHERE CROSS SECTION SHOWS THETA-E DCRSG A BIT WITH HGT ABV TROWAL ACRS THE NCNTRL W OF MQT. WHERE THE PCPN FALLS AS SN...INCRSG WINDS WL CAUSE CONSIDERABLE BLSN. BUT FCST SCENARIO ATTM SEEMS TO SUG WINDS/BLSN WL NOT BE AS SGNFT AS PREVIOUSLY THOUGHT. SINCE THE HEAVIEST SN WL FALL ONLY LATE IN THE SECOND PD AND THE THIRD PD...OPTED TO KEEP GOING WATCH AND NOT UPGRADE TO WRNG...ESPECIALLY SINCE 06Z NAM APPEARS TO BE SLOWER BRINGING IN THE SHARPER DYNAMICS. EXPECT ANY PCPN TO BE ALL SN SUN NGT BUT THEN TO GRDLY DIMINISH AS HGTS RISE FAIRLY SHARPLY IN THE WAKE OF THE DEPARTING UPR LO WITH UPR CNVGC/DNVA/DEEP LYR QVECTOR DVGC. INCOMING AIRMASS DOES NOT APPEAR PARTICULARLY COLD (H85 TEMPS ARND -10C) EITHER WITH HIER MSTR TENDING ...SO LES SHOULD NOT GET OUT OF HAND. BUT PERSISTENT CYC FLOW WL CONT -SHSN THRU THE NGT ALBEIT AT A LIGHTER RATE. COORDINATED WITH APX/GRB/DLH. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... AVIATION FORECASTS ARE A LITTLE TRICKY...PRIMARILY AT CMX. DESPITE PLENTY OF LOW LEVEL MOISTURE AND A SURFACE WIND FROM THE EAST...CMX HAS CEILINGS NOW AT VFR WITH VSBYS LIFR. BASED ON PREVIOUS OBS INDICATED A 1000 FT DECK AND MODEL DATA...DECIDED TO KEEP AT LEAST A LOW MVFR CEILING IN GENERAL. THERE IS ALSO A 100 FT SCT DECK AT THE SITE...WHICH WITH THE EAST WIND...HAVE DECIDED TO INCLUDE A TEMPO FOR A VLIFR DECK. VSBYS AND CEILINGS DROPPING TO LIFR THIS EVENING STILL LOOKS GOOD...AND WITH PLENTY OF MOISTURE/RAIN AROUND ASSOCIATED WITH LOW PRESSURE LIFTING NORTH FROM MISSOURI TOWARDS GREEN BAY...CANNOT IMAGINE CONDITIONS GETTING ANY BETTER AT CMX. RAIN SHOULD CHANGE OVER TO SNOW AT CMX DURING THE DAY SUNDAY. AT SAW...SE WINDS ARE EXPECTED THROUGH THE ENTIRE PERIOD...RESULTING IN UPSLOPE FLOW WHICH SHOULD HELP HOLD CEILINGS AT LIFR. AS FAR AS VSBYS GO...CURRENT LIFR READINGS SHOULD BE ABLE TO HOLD AT LEAST A FEW MORE HOURS...AND PERHAPS THROUGH THE AFTERNOON THANKS TO SNOWMELT MAINTAINING FOG. HOWEVER...THE TYPICAL DIURNAL VARIATION COULD ALLOW VSBYS TO CLIMB TO IFR FOR SOME OF THIS AFTERNOON. A STEADY RAIN DEVELOPING TONIGHT SHOULD ONLY HELP TO KEEP CEILINGS LOW...BUT THERE IS SOME CONCERN FOR VSBYS TO RISE. WILL BANK ON SNOWMELT TO HELP KEEP VSBYS LOW. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... AFTER A GENERAL QUIET PERIOD ON LAKE SUPERIOR THROUGH TONIGHT WITH WINDS NO HIGHER THAN 25 KT (GREATEST NEAR WHITEFISH POINT)...EXPECT WINDS TO REALLY INCREASE SUNDAY. THIS RAPID INCREASE IS DUE TO LOW PRESSURE OVER SOUTHERN MISSOURI THIS EVENING THAT RAPIDLY DEEPENS AS IT HEADS DUE NORTH TOWARD CENTRAL UPPER MICHIGAN. AS THE LOW MOVES TO NEAR MARQUETTE EARLY SUNDAY AFTERNOON...NORTH TO NORTHEAST WINDS ACROSS WESTERN LAKE SUPERIOR SHOULD INCREASE TO GALES. BY SUNDAY EVENING...THERE IS A CHANCE THEY COULD INCREASE TO STORM FORCE... ESPECIALLY NEAR ISLE ROYALE. AS THE LOW SHIFTS FROM NEAR MUNISING SUNDAY EVENING INTO NORTHWEST QUEBEC LATE IN THE NIGHT...WINDS WILL QUICKLY RELAX...DROPPING BELOW GALES ACROSS ALL OF LAKE SUPERIOR JUST AFTER MIDNIGHT SUNDAY NIGHT. WINDS BELOW 30 KT ARE THEN EXPECTED FOR CHRISTMAS EVE INTO WEDNESDAY...WITH A HIGH PRESSURE RIDGE CROSSING MONDAY NIGHT AND A LOW PRESSURE TROUGH CROSSING TUESDAY NIGHT. && .MQT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY MORNING FOR MIZ001>005-009-010-084. WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY AFTERNOON FOR MIZ011. && $$ SYNOPSIS AND SHORT TERM...DLG LONG TERM...KC AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 1025 AM CST SAT DEC 22 2007 .UPDATE...STILL A VERY MURKY FORECAST SCENARIO AS FAR AS CONVECTIVE POTENTIAL TODAY. WHILE CURRENTLY RELATIVELY COOL...STABLE AIR EXISTS OVER THE FORECAST AREA...12Z JAN/LCH SOUNDINGS INDICATE THIS LAYER IS QUITE SHALLOW...WITH STRONG WARM/MOIST ADVECTION OCCURRING JUST ABOVE IT. HENCE...ANY DECENT MIXING SHOULD ACTUALLY MIX DOWN HIGHER SURFACE DEWPOINTS OVER THE AREA. WHILE THERMODYNAMIC ENVIRONMENT FOR ROUBST CONVECTION IS CURRENTLY PRETTY POOR...SHORT TERM MODELS /RUC AND NAM/ INSIST THAT IT WILL IMPROVE QUICKLY AHEAD OF THE FRONT IN NE LA/SE AR AND WESTERN MS. THESE MODELS...AS WELL AS THE JAN LOCAL WRF ENSEMBLE SYSTEM...SHOW THAT MLCAPE VALUES OF 400-800 J/KG SHOULD BE REALIZED BY 00Z AHEAD OF THE FRONT IN AN AREA OF LOW/MID 60S SFC DEWPOINTS. WHILE DEWPOINTS ARE CURRENTLY RISING...BELIEVE IT WILL TAKE SOME SUN TO GET ENOUGH MOISTURE/INSTABILITY TO REALIZE THESE VALUES. VISIBLE SATELLITE DOES SHOW SOME LARGE BREAKS CURRENTLY ACROSS NE LA/WRN WITH THIN SPOTS AND SMALL BREAKS FARTHER WEST ACROSS WRN/CENTRAL LA...BUT TEND TO THINK IT WILL NOT BE AS ROBUST AS MODELS CURRENTLY INDICATE. IN ANY EVENT...A NARROW LINE OF CONVECTION HAS ALREADY DEVELOPED FROM TXK BACK TO NEAR HGX. CONVECTION LOOKS TO BE GETTING MORE ROBUST IN SE TX WHERE BETTER INSTABILITY/MOISTURE IS FEEDING IT...AND IN FACT THERE IS NOW LIGHTNING WITH THIS CONVECTION. THE LINE IS CURRENTLY A BIT AHEAD OF THE COLD FRONT...BUT EXTRAPOLATION BRINGS IT TO THE MS RIVER ABOUT 23Z...WHICH WOULD MEAN IT WOULD BE JUST ABOUT COINCIDENT WITH THE COLD FRONT BY THE TIME IT REACHES OUR AREA. ASSUMING THIS LINE IS THE MAIN CONVECTIVE LINE...THINK IF NOTHING ELSE IT WILL CONTINUE TO BE FED BY MOISTURE/INSTABILITY JUST ABOVE THE SURFACE. IN FACT...JUST TAKING A QUICK LOOK AT NEW GFS IT SHOWS STRONG DESTABILITZATION OCCURRING AT THE 850 MB LEVEL...WITH AN AXIS OF -4 TO -6 SHOWALTER INDICES DEVELOPING THIS AFTERNOON WITH AXIS OF 330+K THETA-E AIR SURGING AHEAD OF LINE. STRONGLY FAVORABLE KINEMATIC ENVIRONMENT WOULD FAVOR EMBEDDED BOW/SUPERCELL STRUCTURES IN SAID LINE. IF LOW LEVEL ENVIRONMENT BECOMES FAVORABLE ENOUGH WITH SOME HEATING/MOISTURE ADVECTION THIS AFTERNOON...SEVERE STORMS WITH DAMAGING WIND GUSTS THE PRIMARY THREAT GIVEN LARGE DCAPE...ALTHOUGH A TORNADO OR TWO WOULD BE POSSIBLE IF MORE ROBUST NEAR SURFACE DESTABILZATION OCCURS AS MODELS SHOW. THREAT SHOULD DIMINISH SOMEHWAT AS LINE MOVES EAST INTO EASTERN MS WITH INSTABILITY WANING EVEN AT THE 900/800 MB LEVEL. WILL UPDATE HWO AND GRAPHICS TO REFLECT LATEST THINKING. WITH REGARD TO WINDS...THEY ARE CURRENTLY NOT RESPONDING AS MUCH AS ORIGINALLY THOUGHT...LIKELY DUE TO CLOUDS AND LACK OF MIXING. HOWEVER...WITH SATELLITE SHOWING SOME SUN BREAKING OUT IN ADVISORY AREA AT THIS TIME...THINK WINDS WILL EVENTUALLY PICK UP AND WILL LEAVE ADVISORY AS IS. THANKS TO SPC FOR THE COORDINATION. && .AVIATION...EXPECT AT LEAST BKN LOW CLOUDS AT MOST LOCATIONS THROUGH THE AFTERNOON WITH A MAINTENANCE OF GENERALLY MVFR CONDITIONS. OCCASIONAL SCT CONDITIONS COULD OCCUR THOUGH AS LARGE BREAKS CURRENTLY ON SATELLITE IN WRN MS. WILL TIME SHRA/TSRA THREAT IN TAFS BASED ON EXPECTED TIMING OF CONVECTIVE LINE. CLOUDS WILL LINGER TONIGHT AFTER FROPA...BUT EXPECT RAPID CLEARING BY SUN AM. && .JAN WATCHES/WARNINGS/ADVISORIES... MS...LAKE WIND ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR MSZ018- 019-025>038-040>044-047>049-053-059-060. LA...LAKE WIND ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR LAZ007>009-015-016-023>026. AR...LAKE WIND ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR ARZ074- 075. && $$ 08 ms AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ALBUQUERQUE NM 906 AM MST SAT DEC 22 2007 .UPDATE...REMOVED THE HIGH WIND WARNING HEADLINE FROM THE NORTHEAST HIGHLANDS AND LOWERED ALL WINDS SPEEDS A NOTCH ACROSS NE NEW MEXICO. 40 && .PREV DISCUSSION...259 AM MST SAT DEC 22 2007 LATEST WATER VAPOR LOOP EARLY THIS MORNING SHOWS AN IMPRESSIVE UPPER LOW PRESSURE SYSTEM OVER THE NE PLAINS WITH A DISTINCT COMMA HEAD AND DRY SLOT FEATURE. RADAR TRENDS SHOW SNOW IS HOLDING STEADY OVER THE NORTHERN MTNS WITH CLEARING FARTHER TO THE WEST AND SOUTH...AND HEAVY SNOW ALONG THE INTERSTATE 40 CORRIDOR FROM SANTA ROSA EAST TO KTCC. WINDS ARE ALSO HOWELING OUT OF THE NORTH AT 30 TO 40 MPH CREATING VERY HAZARDOUS TRAVEL CONDITIONS IN MUCH OF THE NE PART OF THE CWA NORTH OF A FORT SUMNER TO CLOVIS LINE. WILL INCLUDE ADV LEVEL WINDS WITH THE WINTER HAZARD PRODUCTS. IR SAT SHOWS CLEARING OVER THE WESTERN HALF OF THE STATE WITH THE BACK EDGE OF THE COMMA HEAD NEARLY STATIONARY FROM CUBA SE TO KSAF. WILL CANCEL WARNINGS AND ADVISORIES THAT WERE TO EXPIRE AT 600 AM. WARNINGS WILL CONTINUE IN THE EAST WITH ANOTHER 1 TO 3 INCHES ESPECIALLY ALONG INTERSTATE 40 NEAR KTCC. ADVISORY TO THE SOUTH WILL ALSO STAY INTACT MAINLY FOR THE BLOWING SNOW HAZARD APPROACHING FROM THE NORTH. EXPECT CLEARING IN THE EAST AFTER 18Z AS INDICATED BY RUC13 SO DAY SHIFT MAY CONSIDER DROPPING ADVISORY IN THE SE AT THAT TIME. THINK WARNINGS WILL CONTINUE UNTIL 600 PM IN THE NE DUE TO EXTREMELY HAZARDOUS TRAVEL CONDITIONS. VERY COLD NIGHT EXPECTED ACROSS THE CWA...ESPECIALLY IN AREAS WITH SNOWPACK. SUNDAY WILL BE VERY NICE EARLY IN THE DAY WITH INCREASING CLOUDS OVER THE NORTH. NEXT SYSTEM WILL MOVE QUICKLY SE ACROSS THE SANGRES AND NE PLAINS SUNDAY NIGHT WITH ADVISORY LEVEL SNOWS POSSIBLE OVER THE SANGRES SIMPLY DUE TO VERY HIGH SNOW RATIOS. COLD WEATHER CONTINUES MONDAY ACROSS THE REGION DESPITE MOSTLY SUNNY SKIES. 00Z MODELS ARE BEGINNING TO CHANGE THEIR TUNE ON WEATHER PATTERN FOR CHRISTMAS INTO THE NEW YEAR WITH SYSTEMS PASSING FARTHER TO THE NORTH THAN PREVIOUS RUNS. THIS STILL MEANS POSSIBLE SIGNIFICANT WINTER STORMS FOR THE NORTHERN MOUNTAINS AND NE PLAINS HOWEVER THE SOUTH AND WEST MAY ESCAPE WITH GLANCING BLOWS. TWEAKED EXTENDED GRIDS TO ADJUST POPS SLIGHTLY FARTHER NE HOWEVER WILL WAIT FOR A MORE CONSISTENT TREND TO APPEAR. GUYER && .AVIATION... OCCASIONAL IFR CONDITIONS IN SNOW...BLOWING SNOW AND FREEZING FOG TO PERSIST FROM KSAF NORTHEAST AND EASTWARD TO THE TEXAS AND COLORADO BORDER THROUGH MIDDAY. LOCAL MOUNTAIN OBSCURATION ALONG AND WEST OF THE RIO GRANDE VALLEY EXPECTED THROUGH MIDDAY ALSO. NORTHWEST SURFACE WIND TO INCREASE AT KFMN...WITH NORTH TO NORTHWEST WINDS GUSTING TO AROUND 35 OR 40 KTS ALONG AND EAST OF CENTRAL MOUNTAIN CHAIN. WINDS SHOULD TAPER OFF LATE AFTERNOON. NEXT AVIATION DISCUSSION SCHEDULED FOR 22Z. && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 35 14 38 16 / 0 0 5 5 GALLUP.......................... 35 6 40 6 / 0 0 0 0 GRANTS.......................... 35 7 41 9 / 5 0 0 0 GLENWOOD........................ 44 21 52 23 / 0 0 0 0 CHAMA........................... 29 -4 32 -6 / 5 0 10 20 LOS ALAMOS...................... 34 8 37 5 / 10 0 5 5 RED RIVER....................... 20 2 31 5 / 20 0 10 40 TAOS............................ 33 4 38 6 / 20 0 5 20 SANTA FE........................ 32 11 36 8 / 20 0 5 5 SANTA FE AIRPORT................ 36 12 39 16 / 20 0 5 5 ESPANOLA........................ 40 10 42 17 / 20 0 5 5 ALBUQUERQUE HEIGHTS............. 42 20 43 24 / 10 0 0 0 ALBUQUERQUE VALLEY.............. 44 16 45 20 / 10 0 0 0 ALBUQUERQUE FOOTHILLS........... 42 16 41 20 / 20 0 0 0 ALBUQUERQUE WEST MESA........... 43 18 44 23 / 10 0 0 0 SOCORRO......................... 45 19 48 24 / 5 0 0 0 SANDIA PARK/CEDAR CREST......... 37 12 38 14 / 20 0 5 0 MORIARTY/ESTANCIA............... 37 17 40 19 / 30 0 0 0 CARRIZOZO....................... 39 20 42 21 / 20 0 0 0 RUIDOSO......................... 32 17 40 17 / 20 0 0 0 RATON........................... 32 8 40 11 / 30 0 5 20 LAS VEGAS....................... 31 14 38 13 / 50 0 5 20 ROY............................. 35 16 37 15 / 60 0 5 20 CLAYTON......................... 33 14 40 18 / 60 0 0 20 SANTA ROSA...................... 42 16 43 20 / 60 0 0 5 TUCUMCARI....................... 38 13 42 18 / 60 0 0 20 FORT SUMNER..................... 43 19 50 20 / 60 0 0 0 CLOVIS.......................... 37 19 48 21 / 70 0 0 0 PORTALES........................ 39 19 48 20 / 70 0 0 0 ROSWELL......................... 48 22 52 25 / 30 0 0 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 6 PM MST THIS AFTERNOON FOR THE FOLLOWING ZONES...NMZ002>007-010>013. WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS AFTERNOON FOR THE FOLLOWING ZONES...NMZ016>021-026. && $$ GUYER/99 nm AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 627 AM CST SAT DEC 22 2007 .UPDATE... WENT AHEAD AND ISSUED A WIND ADVISORY FOR THE EASTERN PERMIAN BASIN. LATEST RUC SHOWING WINDS 5 TO 10 KTS HIGHER THAN EITHER THE GFS AND NAM ARE SHOWING. SURFACE OBSERVATIIONS TO THE NORTH ARE SHOWING MINIMAL ADVISORY CONDITIONS A THE MOMENT...HOWEVER STRONG DOWNWARD FORCING IN THE WAKE OF THE UPPER LOW AND CLEAR SKIES WILL ALLOW FOR MAXIMUM POTENTIAL OF ELEVATED STRONG WINDS TO MIX TO THE SURFACE. THIS IS A TOUGH CALL WITH THE ADVISORY POSSIBLY NEEDING TO BE EXPANDED SOUTH AND WEST...BUT WANTED TO START OUT HIGHLIGHTING THE AREA WITH THE HIGHEST POTENTIAL FIRST AND WILL LET THE NEXT SHIFT MAKE THE DECISION TO FINE TUNE FURTHER. HENNIG && .PREV DISCUSSION... /ISSUED 518 AM CST SAT DEC 22 2007/ AVIATION... WINDS WILL BE THE BIGGEST PROBLEM TODAY ACROSS AREA TAFS... ALTHOUGH A FEW LOWER CLOUDS COULD ALSO MATERIALIZE ACROSS EASTERN TAF SITES LATER THIS MORNING. EXPECT WINDS TO SWITCH AROUND TO THE NORTH NEAR OR SHORTLY AFTER SUNRISE AS THE COLD FRONT CONTINUES TO PUSH SOUTH THROUGH THE AREA. WINDS BEHIND THE FRONT HAVE BEEN 20KT WITH GUSTS TO GREATER THAN 30KT AT TIMES. THINK WINDS ACROSS THE AREA COULD FOLLOW THIS TREND THROUGH THE AFTERNOON WHEN WINDS SHOULD BEGIN DYING DOWN. EXPECT NEAR CALM WINDS OVERNIGHT. LOW CLOUDS WILL HAVE A CHANCE TO FORM ALONG AND NEAR THE FRONT LATER THIS MORNING. WILL LIKELY ONLY BRIEFLY TOUCH MVFR CONDITIONS BEFORE QUICKLY GOING BACK TO VFR CONDITIONS AGAIN. THEN VFR CONDITIONS WILL BE EXPECTED THIS AFTERNOON AND INTO THE OVERNIGHT HOURS TONIGHT. /13/ PREV DISCUSSION... /ISSUED 329 AM CST SAT DEC 22 2007/ DISCUSSION... COLD FRONT HAS MOVED THROUGH THE TEXAS PANHANDLE AND WILL BE INTO THE NORTHERN PERMIAN BASIN NOT LONG AFTER SUNRISE. WINDS WILL SHIFT AROUND TO THE NORTH BEHIND THE FRONT AND BECOME BREEZY TO WINDY AS STRONG CAA DOMINATES IN THE WAKE OF THE DEPARTING UPPER LEVEL LOW. WINDS ARE CURRENTLY GUSTING IN EXCESS OF 40 KTS BEHIND THE FRONT AND A WIND ADVISORY MAY NOT BE OUT OF THE QUESTION FOR TODAY BUT A WEAKER PRESSURE GRADIENT IN THE PB SHOULD PRECLUDE ISSUANCE. WENT AHEAD AND LEFT POPS IN THE EXTREME NORTHERN COUNTIES...BUT GIVEN THE PRONOUNCED DRY SLOT OVER THE CWA ON WV IMAGERY...RAIN OR SNOW CHANCES SEEM PRETTY DISMAL. ELSEWHERE IN THE SHORT TERM STRONG WINDS IN THE HIGHER ELEVATIONS ARE BEGINNING TO SUBSIDE AND THE HIGH WIND WARNING WILL MOST LIKELY BE ALLOWED TO EXPIRE...THOUGH WINDS IN THE DAVIS MOUNTAINS ARE STILL PRETTY HIGH AND WILL NEED TO BE CLOSELY WATCHED. THE REMAINDER OF THE FORECAST PACKAGE WILL BE A SERIES OF REPEAT PERFORMANCES AS ZONAL FLOW SENDS SEVERAL UPPER LEVEL LOWS ACROSS THE CENTRAL PLAINS WHICH IN TURN WILL GIVE US MULTIPLE COLD FRONTAL PASSAGES. THIS FORECAST PACKAGE STAYED CLOSE TO THE GFS. THE 21/12Z ECMWF SEEMED TOO SLOW AND DEEP WITH THE UPPER PATTERN...ESPECIALLY WITH REGARDS THE LOW SEEN APPROACHING AROUND CHRISTMAS. WE SHOULD SEE SEVERAL SHOTS OF COOL AIR BUT WE ARE NOT GOING TO BE ABLE TO TAP INTO ANY ARCTIC AIR SO THE TEMPS WILL BE QUICK TO REBOUND. CHRISTMAS PROMISES TO BE A NICE DAY WITH DRY WEATHER AND NEAR TO ABOVE NORMAL TEMPERATURES. HENNIG && .MAF WATCHES/WARNINGS/ADVISORIES... NM...HIGH WIND WARNING FROM 5 AM TO 9 AM MST THIS MORNING FOR THE FOLLOWING ZONES...GUADALUPE MOUNTAINS OF EDDY COUNTY. TX...WIND ADVISORY FROM 10 AM THIS MORNING TO 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES...BORDEN...DAWSON...GLASSCOCK... HOWARD...MARTIN...MIDLAND...MITCHELL...REAGAN...SCURRY... UPTON. HIGH WIND WARNING FROM 6 AM CST /5 AM MST/ TO 10 AM CST /9 AM MST/ THIS MORNING FOR THE FOLLOWING ZONES...DAVIS/APACHE MOUNTAINS AREA...GUADALUPE MOUNTAINS. && $$ 10 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 552 AM CST SAT DEC 22 2007 .AVIATION... WINTRY WEATHER WILL MAINTAIN IFR/LIFR CONDITIONS DURING THE MORNING HOURS AS THE TRAILING EDGE OF THE EXITING LOW PRESSURE SYSTEM PRODUCING SNOW AND BLOWING SNOW. THOUGH THE SNOW SHOULD END BY MIDDAY OVER KAMA...KDHT AND KGUY...STRONG WINDS WILL CONTINUE INTO THE AFTERNOON. VFR CONDITIONS SHOULD RETURN BY LATE AFTERNOON. NUNEZ && .PREV DISCUSSION... /ISSUED 442 AM CST SAT DEC 22 2007/ DISCUSSION... MAIN FORECAST CONCERN DEALS WITH THE SHORT TERM DETAILS WHICH INCLUDES PRECIP TIMING AND WINDS. CURRENT WV IMAGERY WITH RUC UPPER AIR ANALYSIS OVERLAY SHOW A VIGOROUS UPPER TROUGH OVER NEW MEXICO. A 120 KT JET WAS PUNCHING INTO THE BASE OF THE TROUGH...WHICH WILL ACT TO ACCELERATE IT NORTHEAST TO THE GREAT LAKES BY SUN. CURRENT RADAR SHOWS AN AREA OF MIXED PRECIPITATION SPREADING INTO PORTIONS OF THE PANHANDLES. WITH SFC TEMPS HOVERING NEAR OR BELOW FREEZING...EXPECT A CHANGE OVER TO ALL SNOW SOON. FOR TODAY...THE UPPER TROUGH WILL QUICKLY MOVE ACROSS THE TEXAS PANHANDLE. STRONG UPPER DYNAMICS WILL REMAIN ACROSS THE PANHANDLES THIS MORNING...SO EXPECT THE HEAVIEST SNOWFALL TO OCCUR THEN. ONE CAVEAT TO THIS IS THAT SFC WINDS DO NOT HAVE MUCH OF AN UPSLOPE COMPONENT WHICH WOULD LIMIT THE AMOUNT OF LLVL MOISTURE. IRREGARDLESS...FCST SOUNDINGS INDICATE FAIRLY SATURATED PROFILES WITH TEMPS BELOW FREEZING THROUGHOUT THE COLUMN SO PRECIP THIS MORNING SHOULD BE ALL SNOW. SINCE THIS IS A PROGRESSIVE SYSTEM... SNOW WILL END FROM WEST TO EAST AND ADJUSTED POPS TO END THE TIMING OF THE SNOW SOONER ACROSS THE WESTERN PORTIONS OF THE CWA. STILL EXPECT THE GREATEST ACCUMULATIONS IN THE OKLAHOMA PANHANDLE WHERE CLOSE TO 4 INCHES IS POSSIBLE. GIVEN THIS...CONTINUED THE SNOW AND BLOWING SNOW ADVISORY WHICH EXPIRES THIS EVENING. IN ADDITION TO PRECIP...STRONG NORTHERLY WINDS WILL CONTINUE TODAY BEFORE DIMINISHING TONIGHT. CURRENT OBS ALREADY SHOW SPEEDS IN EXCESS OF 30 KTS IN THE FAR NORTHWEST PORTION OF THE PANHANDLES AND THE TUCUMCARI PROFILER SHOWS WINDS OF 35 KTS AROUND 900 MB. WITH STRONG CAA AND PRESSURE RISES ON THE ORDER OF 5 MB...SEE NO REASON WHY THE CWA WILL NOT SEE ADVISORY CRITERIA WINDS SO HOISTED A WIND ADVISORY FOR THE ENTIRE CWA THROUGH 6 PM THIS EVENING. SKIES WILL RAPIDLY CLEAR TONIGHT AND WITH DIMINISHING WINDS AND AN ANTICIPATED FRESH SNOW PACK...WENT SLIGHTLY UNDER MOS GUIDANCE FOR TEMPS TONIGHT...WITH LOWS MAINLY IN THE TEENS. MODELS CONTINUE TO ADVERTISE A PROGRESSIVE WEATHER PATTERN AS SEVERAL UPPER TROUGHS MOVE ACROSS THE PLAINS. THE FIRST WILL DROP SOUTHEAST OUT OF THE INTER MOUNTAIN WEST AND MOVE ACROSS THE CWA SUN NIGHT AND MON. DID INCREASE POPS A BIT BUT STILL KEPT THEM SILENT AS ASCENT INCREASES AHEAD OF THE APPROACHING UPPER TROUGH ALTHOUGH MID AND UPPER MOISTURE REMAINS LIMITED. ANOTHER UPPER TROUGH IS PROGGED TO DROP SOUTHEAST ON CHRISTMAS DAY AND CROSS THE PANHANDLES THAT NIGHT. THIS SYSTEM LOOKS TO TAP INTO MORE MOISTURE SO MAINTAINED SLIGHT CHANCE POPS. DID PUSH BACK THE TIMING OF PRECIP TO THAT EVENING AS SYNOPTIC SCALE LIFT AND MOISTURE LOOKS TO BE MAXIMIZED THEN. FINAL TROUGH WILL ALSO DROP SOUTHEAST AND MOVE ACROSS THE CENTRAL PLAINS THU. THE OPERATIONAL GFS IS MORE PROGRESSIVE THAN ENSEMBLES SO KEPT THE DRY FCST INTACT. AS FOR TEMPS...GENERALLY FOLLOWED MEXMOS GUIDANCE WITH TEMPS GENERALLY RUNNING BELOW AVERAGE. CLK && .AMA WATCHES/WARNINGS/ADVISORIES... TX...SNOW AND BLOWING SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH... DALLAM...DEAF SMITH...DONLEY...GRAY...HANSFORD...HARTLEY... HEMPHILL...HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE... OLDHAM...POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...DALLAM...DEAF SMITH...DONLEY...GRAY...HANSFORD...HARTLEY...HEMPHILL... HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE...OLDHAM... POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. OK...SNOW AND BLOWING SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. && $$ 08/05 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AMARILLO TX 442 AM CST SAT DEC 22 2007 .DISCUSSION... MAIN FORECAST CONCERN DEALS WITH THE SHORT TERM DETAILS WHICH INCLUDES PRECIP TIMING AND WINDS. CURRENT WV IMAGERY WITH RUC UPPER AIR ANALYSIS OVERLAY SHOW A VIGOROUS UPPER TROUGH OVER NEW MEXICO. A 120 KT JET WAS PUNCHING INTO THE BASE OF THE TROUGH...WHICH WILL ACT TO ACCELERATE IT NORTHEAST TO THE GREAT LAKES BY SUN. CURRENT RADAR SHOWS AN AREA OF MIXED PRECIPITATION SPREADING INTO PORTIONS OF THE PANHANDLES. WITH SFC TEMPS HOVERING NEAR OR BELOW FREEZING...EXPECT A CHANGE OVER TO ALL SNOW SOON. FOR TODAY...THE UPPER TROUGH WILL QUICKLY MOVE ACROSS THE TEXAS PANHANDLE. STRONG UPPER DYNAMICS WILL REMAIN ACROSS THE PANHANDLES THIS MORNING...SO EXPECT THE HEAVIEST SNOWFALL TO OCCUR THEN. ONE CAVEAT TO THIS IS THAT SFC WINDS DO NOT HAVE MUCH OF AN UPSLOPE COMPONENT WHICH WOULD LIMIT THE AMOUNT OF LLVL MOISTURE. IRREGARDLESS...FCST SOUNDINGS INDICATE FAIRLY SATURATED PROFILES WITH TEMPS BELOW FREEZING THROUGHOUT THE COLUMN SO PRECIP THIS MORNING SHOULD BE ALL SNOW. SINCE THIS IS A PROGRESSIVE SYSTEM... SNOW WILL END FROM WEST TO EAST AND ADJUSTED POPS TO END THE TIMING OF THE SNOW SOONER ACROSS THE WESTERN PORTIONS OF THE CWA. STILL EXPECT THE GREATEST ACCUMULATIONS IN THE OKLAHOMA PANHANDLE WHERE CLOSE TO 4 INCHES IS POSSIBLE. GIVEN THIS...CONTINUED THE SNOW AND BLOWING SNOW ADVISORY WHICH EXPIRES THIS EVENING. IN ADDITION TO PRECIP...STRONG NORTHERLY WINDS WILL CONTINUE TODAY BEFORE DIMINISHING TONIGHT. CURRENT OBS ALREADY SHOW SPEEDS IN EXCESS OF 30 KTS IN THE FAR NORTHWEST PORTION OF THE PANHANDLES AND THE TUCUMCARI PROFILER SHOWS WINDS OF 35 KTS AROUND 900 MB. WITH STRONG CAA AND PRESSURE RISES ON THE ORDER OF 5 MB...SEE NO REASON WHY THE CWA WILL NOT SEE ADVISORY CRITERIA WINDS SO HOISTED A WIND ADVISORY FOR THE ENTIRE CWA THROUGH 6 PM THIS EVENING. SKIES WILL RAPIDLY CLEAR TONIGHT AND WITH DIMINISHING WINDS AND AN ANTICIPATED FRESH SNOW PACK...WENT SLIGHTLY UNDER MOS GUIDANCE FOR TEMPS TONIGHT...WITH LOWS MAINLY IN THE TEENS. MODELS CONTINUE TO ADVERTISE A PROGRESSIVE WEATHER PATTERN AS SEVERAL UPPER TROUGHS MOVE ACROSS THE PLAINS. THE FIRST WILL DROP SOUTHEAST OUT OF THE INTER MOUNTAIN WEST AND MOVE ACROSS THE CWA SUN NIGHT AND MON. DID INCREASE POPS A BIT BUT STILL KEPT THEM SILENT AS ASCENT INCREASES AHEAD OF THE APPROACHING UPPER TROUGH ALTHOUGH MID AND UPPER MOISTURE REMAINS LIMITED. ANOTHER UPPER TROUGH IS PROGGED TO DROP SOUTHEAST ON CHRISTMAS DAY AND CROSS THE PANHANDLES THAT NIGHT. THIS SYSTEM LOOKS TO TAP INTO MORE MOISTURE SO MAINTAINED SLIGHT CHANCE POPS. DID PUSH BACK THE TIMING OF PRECIP TO THAT EVENING AS SYNOPTIC SCALE LIFT AND MOISTURE LOOKS TO BE MAXIMIZED THEN. FINAL TROUGH WILL ALSO DROP SOUTHEAST AND MOVE ACROSS THE CENTRAL PLAINS THU. THE OPERATIONAL GFS IS MORE PROGRESSIVE THAN ENSEMBLES SO KEPT THE DRY FCST INTACT. AS FOR TEMPS...GENERALLY FOLLOWED MEXMOS GUIDANCE WITH TEMPS GENERALLY RUNNING BELOW AVERAGE. CLK && .PRELIMINARY POINT TEMPS/POPS... AMARILLO TX 34 18 42 21 42 / 70 0 0 10 5 BEAVER OK 29 13 40 19 37 / 90 0 0 10 10 BOISE CITY OK 32 12 40 18 41 / 70 0 0 10 10 BORGER TX 32 18 43 22 42 / 80 0 0 10 10 BOYS RANCH TX 33 15 43 20 42 / 60 0 0 10 5 CANYON TX 34 16 43 20 43 / 60 0 0 10 5 CLARENDON TX 34 20 45 24 44 / 70 0 0 10 5 DALHART TX 33 13 42 19 42 / 60 0 0 10 5 GUYMON OK 31 14 41 18 41 / 90 0 0 10 10 HEREFORD TX 35 15 46 20 42 / 60 0 0 10 5 LIPSCOMB TX 29 15 41 19 41 / 90 0 0 10 10 PAMPA TX 30 19 43 23 42 / 80 0 0 10 10 SHAMROCK TX 33 21 45 23 43 / 80 0 0 5 10 WELLINGTON TX 34 21 45 24 43 / 70 0 0 5 5 && .AMA WATCHES/WARNINGS/ADVISORIES... TX...SNOW AND BLOWING SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH... DALLAM...DEAF SMITH...DONLEY...GRAY...HANSFORD...HARTLEY... HEMPHILL...HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE... OLDHAM...POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...DALLAM...DEAF SMITH...DONLEY...GRAY...HANSFORD...HARTLEY...HEMPHILL... HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE...OLDHAM... POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. OK...SNOW AND BLOWING SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. && $$ 05/08 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 226 PM MST SAT DEC 22 2007 .SHORT TERM... (TONIGHT AND SUNDAY) ...MUCH QUIETER...BUT COLD...NIGHT FOR SOUTHERN CO TONIGHT... CURRENTLY...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES SHOWED THE QUICK MOVING WEATHER SYSTEM THAT STRUCK CO YESTERDAY WAS IN THE CENTRAL AND SOUTHERN PLAINS. BRILLIANT SUNSHINE WAS ACROSS MUCH OF SOUTHERN CO THIS AFTERNOON. BRISK WINDS CONTINUE ACROSS THE FAR SOUTHEASTERN CO PLAINS...BUT WILL LIKELY DIMINISH SHORTLY AS THE WEATHER SYSTEM CONTINUES TO PULL AWAY. VISIBLE SATELLITE IMAGERY BEAUTIFULLY SHOWED THE AREAS OF SNOW AND NO SNOW. AS ANTICIPATED... SOUTHERN EL PASO...NORTHERN PUEBLO...AND CROWLEY COUNTIES DID NOT GET MUCH...IF AT ALL...ACCUMULATING SNOW THANKS TO THE INTENSE DOWNSLOPE(DRYING) FLOW OFF THE SOUTHERN PALMER DIVIDE LAST NIGHT. TERRAIN RULES. DESPITE FULL SUNSHINE...TEMPERATURES HAVE STRUGGLED TO CLIMB IN THE LOWER AR RIVER VALLEY GIVEN A LOW SUN ANGLE AND RELATIVELY LIGHT WIND. MUCH OF THE SAN LUIS VALLEY RECEIVED 1-6 INCHES...WIDESPREAD 4-6 INCHES ACROSS CENTRAL/SOUTHERN PART OF THE VALLEY AND NO SURPRISE TEMPERATURES ARE STRUGGLING TO REACH 20F. MOS GUIDANCE HAS NO CLUE. TONIGHT...MIDDLE TO UPPER LEVEL NORTH FLOW BACKS TO WEST-NORTHWEST FLOW. ALWAYS GET A LITTLE CONCERNED ABOUT MOUNTAIN WAVE DEVELOPMENTS DURING THIS WEATHER PATTERN TRANSITION PHASE...ESPECIALLY ALONG THE EAST-SOUTHEAST SLOPE OF PIKES PEAK AND THE EAST SLOPES OF THE RAMPART RANGE. WIND AND THERMAL STRUCTURE IN NAM12 CROSS-SECTIONS NOT SHOWING THE STRONGEST MOUNTAIN WAVE PATTERN. MIGHT JUST BE A TRAPPED MOUNTAIN WAVE EVENT...HOWEVER...COULD NOT RULE OUT SOME WIND GUSTS OF 30-40 MPH ALONG THE EASTERN PIKES PEAK AND RAMPART RANGE SLOPES...ESPECIALLY AROUND THE AIR FORCE ACADEMY AREA LATE TONIGHT/EARLY SUN MORNING. HIGH LEVEL MOISTURE MOVING OUT OF THE PACIFIC NORTHWEST WILL LIKELY LEND ITSELF TO MOUNTAIN WAVE CLOUD DEVELOPMENT ALONG THE CO FRONT RANGE LATE TONIGHT AND SUN MORNING. DRAMATIC TEMPERATURES GRADIENTS WILL LIKELY EXIST ACROSS SOUTHERN CO. AREAS OF SNOW COVER ACROSS THE MOUNTAIN VALLEYS WILL BE IN THE SINGLE DIGITS OR SLIGHTLY BELOW ZERO. THE SAN LUIS VALLEY WITH ITS FRESH SNOW COVER WILL PROBABLY SEE 10 BELOW TO 20 BELOW ZERO TEMPERATURES LATE TONIGHT/EARLY SUN MORNING. WENT A FEW CATEGORIES BELOW MOS AND THAT MIGHT NOT BE ENOUGH. THE ONLY THING THAT COULD KEEP TEMPERATURES UP WOULD BE HIGH CLOUDS AND/OR THE WIND PICKING UP. MEANWHILE...THE EASTERN SLOPE OF OUR EASTERN CO MOUNTAINS IN THE THERMAL (BANANA-BELT) WILL SEE TEMPERATURES HOLD STEADY OR SLOWLY RISE TONIGHT AS WEST-NORTHWEST FLOW CHINOOK PATTERN DEVELOPS. TEMPERATURES ACROSS THE SNOWPACK SOUTH OF HIGHWAY 50 WILL BE PROBLEMATIC...ESPECIALLY WITH RELATIVELY LIGHT WINDS AND SURFACE DEW POINTS ALREADY IN THE SINGLE DIGITS. THE LOW LEVEL COLD AIR OFF THE SNOWPACK MIGHT ACTUALLY DRAIN INTO THE LOWER AR RIVER VALLEY... DOWNSLOPE...TOWARDS PUEBLO-LA JUNTA-LAMAR LATE TONIGHT. HOWEVER... ANY MOUNTAIN WAVE CLOUD DEVELOPMENT COULD TEMPER NOCTURNAL COOLING IN THE LOWER AR RIVER VALLEY. MIGHT SEE SOME PATCHY FREEZING FOG...DENSE AT TIMES...IN THE SAN LUIS VALLEY CENTER FLOOR CONSIDERING IT HAPPENED EARLY THIS MORNING. BUFKIT ALS MODEL SOUNDING ANALYSIS SUGGEST IT...TOO. SUNDAY...NEXT WEAK WEATHER FEATURES IS STILL PROJECTED TO MOVE THROUGH THE CENTRAL ROCKIES...MAINLY SUN AFTERNOON. NOT A LOT OF MOISTURE AND LIFT ASSOCIATED WITH THIS SYSTEM. THE NAM DOES NOT GENERATE MUCH IN THE WAY OF QPF...AND THE GFS HAS A LITTLE MORE. PLAN TO STICK WITH THE CURRENT POP/WX FORECAST EAST OF THE CONTINENTAL DIVIDE AND TRENDED TOWARDS GJT/BOU FORECASTS AROUND THE CONTINENTAL DIVIDE. HIGH TEMPERATURES WILL BE A GREAT CHALLENGE GIVEN RELATIVELY LIGHT SURFACE-PBL WIND...LOW SUN ANGLE...RELATIVELY FRESH SNOW COVER FOR SOME AREA...AND ANY MOUNTAIN WAVE CLOUDS. THE SAN LUIS VALLEY AND LOWER AR RIVER VALLEYS WILL BE THE LAST TO WARM GIVEN THE AFOREMENTIONED CONDITIONS. HAVE ADJUSTED THE DIGITAL DATABASE AS SUCH. AGAIN...WENT A COUPLE OF CATEGORIES BELOW MOS FOR ALS IN THE SAN LUIS VALLEY CENTER FLOOR. MET MOS HAS 36F AND DOUBT THAT UNLESS THE WIND PICKS UP. METZE .LONG TERM... (SUNDAY NIGHT THROUGH SATURDAY) ...ACTIVE PATTERN TO CONTINUE DURING THE LONG TERM... METEOROLOGICAL CHALLENGE IS IMPACT THAT SERIES OF SYSTEMS WILL HAVE ON CWFA DURING THE LONG TERM. INITIAL SYSTEM(#1) IS EXPECTED TO GENERATE LIGHT SNOW(BASICALLY AN ADDITIONAL 2 INCHES OR LESS OF SNOW FROM SUNSET SUNDAY TO SUNRISE MONDAY) OVER THE HIGHER TERRAIN AREAS WITH UPPER RIDGING THEN LEADING TO DRY CONDITIONS ON MONDAY. BY CHRISTMAS EVE...UPPER LOW DEVELOPS OVER NORTHERN UTAH AND IS PROJECTED TO BECOME CENTERED OVER SOUTHEASTERN UTAH BY 12Z CHRISTMAS MORNING AND THEN PUSHES INTO THE TEXAS PANHANDLE REGION BY SUNSET CHRISTMAS. THIS SYSTEM(#2) IS EXPECTED TO GENERATE WESTERN AND CENTRAL MOUNTAIN SNOW MONDAY EVENING WITH SNOW THEN DEVELOPING OVER THE REMAINDER OF THE CWFA MONDAY NIGHT AND CONTINUING INTO CHRISTMAS. AT THIS TIME...POTENTIAL SNOW AMOUNTS APPEAR TO BE ON THE LIGHTER SIDE...GENERALLY 4 INCHES OR LESS OVER THE MAJORITY OF THE CWFA(WITH POSSIBLY SEVERAL MORE INCHES OVER SECTIONS OF ZONE 68) AND WILL DEPICT THIS IN IMPENDING GRIDS/ZONES. WFO PUEBLO WILL CONTINUE TO MONITOR THIS SYSTEM AS WELL AS THE OTHER SYSTEMS FOR FUTURE TRACK AND INTENSITY CHANGES. FROM TUESDAY NIGHT INTO WEDNESDAY...DRY CONDITIONS SHOULD RETURN TO REGION AS ZONAL UPPER FLOW DOMINATES. NEXT UPPER SYSTEM(#3) IS THEN EXPECTED TO DEVELOP OVER NORTHEAST WYOMING BY WEDNESDAY NIGHT AND THEN PUSH INTO SOUTH DAKOTA ON THURSDAY. THIS DISTURBANCE SHOULD GENERATE ANOTHER ROUND OF SNOW SHOWERS OVER SECTIONS OF THE CWFA...ESPECIALLY THE CENTRAL MOUNTAINS...FROM WEDNESDAY EVENING INTO THURSDAY. ANOTHER BRIEF BREAK FROM THE PRECIPITATION THREAT IS EXPECTED TO BE NOTED FROM THURSDAY NIGHT INTO FRIDAY MORNING BEFORE SYSTEM(#4) DEVELOPS OVER SOUTHERN NEVADA BY 18Z FRIDAY AND THEN MOVES ACROSS NEW MEXICO ON SATURDAY. THIS WAVE IS EXPECTED TO GENERATE INCREASING POPS FROM FRIDAY AFTERNOON INTO SATURDAY. OVERALL TEMPERATURES SHOULD CONTINUE TO RUN BELOW CLIMATOLOGICAL AVERAGES DURING THE LONG TERM WITH THE MILDEST TEMPERATURES EXPECTED ON MONDAY(CHRISTMAS EVE). && .AVIATION... PER SHORT TERM DISCUSSION...VFR CONDITIONS WILL CONTINUE FOR THE COS AND PUB AIRPORTS. ALS WILL LIKELY SEE 1-3 BR IFR CIGS DEVELOP AFT 05Z/23 WITH TEMPORALLY CHANGES TO 1/4SM FZFG AND LIFR CIGS BETWEEN 11Z-15Z/23. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 1155 AM CST SAT DEC 22 2007 .SHORT TERM... STORM BEGINNING TO TAKE SHAPE TO THE SOUTH OVER KANSAS AND MISSOURI WITH PRECIPITATION RAPIDLY SPREADING NORTHEAST. AT THE SAME TIME...DRIER AIR HAS WORKED INTO NORTHWEST IOWA AND THE COMBINATION WILL PROVIDE A SHARP CUTOFF TO THE SNOW LINE. DID CANCEL A PORTION OF THE SNOW AND BLOWING SNOW ADVISORY OVER THE NORTHWEST WHERE SNOWFALL SHOULD BE LIMITED. STILL APPEARS MUCH OF THE WARNING HAS A STRONG CHANCE FOR 4 INCHES PLUS WITH A FEW AREAS POSSIBLY TOPPING 8 INCHES. SOME QUESTION DOES STILL REMAIN OVER A FEW COUNTIES ON THE NORTHWEST EDGE BUT AT THIS TIME NOT CONFIDENT ENOUGH TO DROP THEM YET. STRONG FORCING WITHIN THE DENDRITIC LAYER THIS AFTERNOON SHOULD PROVIDE A PERIOD OF ONE TO TWO INCH PER HOUR RATES ESPECIALLY GIVEN THE CONVECTIVE NATURE OF THE ACTIVITY THAT WILL ARRIVE OVER THE SOUTH CENTRAL SOON. ONE THIS BAND HITS...COGNITIONS WILL QUICKLY DETERIORATE. && .DISCUSSION... OBVIOUS PRIMARY CONCERN WILL BE IMPACT OF WEEKEND STORM...BUT WILL HAVE TO DEAL WITH DENSE FOG ADVY FIRST. WITH INCREASING NWLY WINDS ALREADY TO ICL-CIN-EST LINE WITH CFP HAVE SHIFTED ADVY EWD AND IS NOW IN EFFECT E OF THESE AREAS TIL 15Z AND BASICALLY I35 CORRIDOR EWD TIL 18Z. TEMPS SHOULD BE FALLING SO FORECAST HIGHS ARE VERY CLOSE TO CURRENT READINGS. REGARDING THE WINTER STORM...NAM SEEMED TO INITIALIZE JUST A TAD BIT BETTER AT 00Z WITH SLIGHTLY DEEPER FEATURES THROUGH DEPTH OF ATMOSPHERE. HOWEVER WILL BE FAVORING GFS AS WELL AS 00Z SPC WRF AND THEIR MORE WLY QPF SOLUTION. CONFIDENCE NOT THE GREATEST WITH 00Z ECMWF AND 06Z NAM STILL GOING FARTHER E. HOWEVER GFS...ALONG WITH 06Z RUC...SEEM TO HAVE BETTER HANDLE ON CURRENT WX AFTER 06Z AND EXTRAPOLATION OF DEVELOPING DEF ZN INTO IA.. THIS WOULD SUGGEST THAT FARTHER W SOLUTION THE WAY TO GO WITH HEAVIER SNOWS BACK INTO DSM METRO AND POINTS S AND E. MODEL BIASES OFTEN PLACE HEAVIER ACCUMS TOO FAR SE...WITH THE NAM OFTEN SEEMING TO BE SHADING HIGHER QPF AMOUNTS TOO CLOSE TO CONVECTION AND NOT EMPHASIZING DEF ZN ADEQUATELY. MUCH LIKE YESTERDAY...FORCING IN DENDRITIC LAYER SEEMS TO BE IN H5/H6 LAYER OR AROUND 300/305K ISENT SFCS. UVM IN THESE AREAS OF CONCERN SPREAD NEWD INTO IA BY 18Z BUILDING ON SE-NE ORIENTED BAND ALREADY DEVELOPING ON RADAR. ALTHOUGH SOME THETA-E ADVECTION AND FRONTOGENETICAL FORCING IS NOTED...BRUNT OF UVM SEEMS TO BE DRIVEN BY DPVA AS SHRT WV LIFTS OUT. THIS STILL RESULTS IN STRONG OVERALL QG FORCING INTO THE AFTN BEFORE REACHING FAR ERN PORTIONS THIS EVE. SERN FRINGE OF THIS AREA WILL SEE THETA-E LAPSE RATES AND EPV GOING NEGATIVE SO EXPECT STATIC STABILITY WILL BE QUITE LOW. LIGHTNING HAS ALREADY BEEN OBSERVED NEAR LOW CORE AND WOULD NOT BE SURPRISED TO BRIEFLY SEE SOME CONVECTIVE ELEMENTS BEFORE STABILITY MIN MOVES INTO IL THIS EVE. CURRENT SNOW TOTALS VARY FROM 4-7 INCHES IN THE WARNING...BUT COULD SEE ISOLD HIGHER AMOUNTS IF CONVECTION PANS OUT. THIS CONVECTION AND POTENTIAL LATENT HEAT RELEASE MAY BE ANOTHER REASON TO FAVOR MORE NWLY GFS SOLUTION WITH LOWER PRESSURES INTO COLDER AIR. ALSO JUST NOTICED 06Z NAM HAS STRONG DENDRITIC FORCING BACK INTO ALO-OTM CORRIDOR THROUGH 06Z BUT QPF NOT FAR ENOUGH WWD TO REFLECT THAT. ANOTHER REASON TO FAVOR 00Z GFS. HAVE SWITCHED PREVIOUS WATCH TO WINTER STORM WARNING AND ADVY. WRNG IS ESSENTIALLY WHERE SNOW AMOUNTS ARE EXPECTED TO BE 4 INCHES PLUS. THIS FUDGES CRITERIA SOMEWHAT...BUT BLENDS WELL INTO ADJACENT HEADLINES AND AM NOT GOING TO WORRY ABOUT DETAILS CONSIDERING THE BLOWING SNOW POTENTIAL. JUST TO THE NW...SNOW AND BLOWING SNOW ADVY IN EFFECT WHERE AMOUNTS SHOULD REACH 1-4". SFC PRESSURES GO FROM JUST ABOVE 1000MB THIS EVE TO 985 OR LESS BY MIDDAY SUN WHEN LOW REACHES GREAT LAKES. THIS WILL REALLY CRANK THE WINDS UP WITH IMPRESSIVE ISALLOBARIC COMPONENT AND PRES GRADIENT LIKELY PUSHING WINDS INTO BLIZZARD WARNING POTENTIAL ERN HALF. NRN IL LOOKS TO BE HIT ESPECIALLY HARD. THIS WOULD BE LATE 2ND PERIOD SO WILL LEAVE THAT UPGRADE FOR LATER SHIFTS BUT WOULD NOT BE SURPRISED IF IT IS REACHED EARLY SUN WITH PROJECTED GUSTS INTO THE LOWER/MIDDLE 30KTS. EXPECT PLENTY OF WRAP AROUND STRATUS AND POTENTIALLY FLURRIES CONTINUING LATER SUN AND SUN NIGHT. NO CHANGES TO LATER PERIODS. CONSIDERING STRENGTH OF CAA...SNOW COVER AND PERSISTENT LOW CLOUDS HAVE GONE JUST BELOW COOLEST GUIDANCE FOR HIGHS SUN. DO NOT SEE MUCH THERMAL CHANGE SUN NIGHT WITH MORE STRATUS AND WINDS KEEPING THINGS MIXED SO ONLY WENT WITH SEVERAL DEGREE DIURNAL DROP TOWARD HIGHER END OF GUIDANCE. LOW LEVEL MOISTURE LINGERS INTO MON AND WITH INVERSION STILL IN PLACE AROUND SOLAR MIN DO NOT SEE MUCH HOPE FOR REBOUND. HAVE CLIPPED CURRENT MON FORECAST QUITE A BIT NOW GOING AT LEAST A CATEGORY BELOW COOLEST GUIDANCE...WHICH IS A BLEND OF RAW TEMPS. MAY HAVE TO GO EVEN FURTHER IN UPCOMING PACKAGES. && .AVIATION...22/18Z WINTER STORM BEGINNING TO GET UNDERWAY OVER SOUTH CENTRAL IOWA WHILE A COLD FRONT HAS BROUGHT MUCH DRIER AIR INTO THE NORTHWEST. EXPECT DSM/ALO/OTM TO BE NEAR THE BRUNT OF THE STORM WHILE MCW AND FOD REMAIN JUST TO THE NORTHWEST. WIDESPREAD LIFR CONDITIONS WILL BE LIKELY FOR SEVERAL HOURS THIS AFTERNOON AND THIS EVENING AT DSM/ALO/OTM BEFORE GRADUAL IMPROVEMENTS OVERNIGHT. IFR TO MVFR VISIBILITIES MAY CONTINUE OVERNIGHT DUE TO BLOWING SNOW AS NORTHWEST WINDS REMAIN GUSTY. CEILINGS WILL RAISE FOR A PERIOD OVERNIGHT THOUGH MORE STRATUS SHOULD DROP OUT OF THE NORTHWEST SUNDAY MORNING. && .DMX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVY FOR EAST CENTRAL PORTION OF CWA THROUGH 15Z. WINTER STORM WARNING BASICALLY ALONG AND EAST OF CORNING-AMES-HAMPTON LINE 18Z-12Z. SNOW AND BLOWING SNOW ADVY BASICALLY ALONG AND EAST OF DNS-CIN-AXA LINE BLENDING INTO WARNING...21Z-12Z. && $$ SHORT TERM/AVIATION...DONAVON LONG TERM...SMALL/ALBRECHT ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 145 PM CST SAT DEC 22 2007 .SHORT TERM... INTENSE 500 MB SHORTWAVE OVER THE SOUTHERN PLAINS WILL LIFT NORTHEAST ACROSS THE LOWER OHIO VALLEY TONIGHT. SURFACE CYCLONE OVER EXTREME NE OKLAHOMA WILL DEEPEN AS IT TRACKS ACROSS THE KSTL AREA BY 06Z. STRONG LOW LEVEL WIND FIELDS WITH THIS SYSTEM WILL BE THE PRIMARY CONCERN. GRADIENT WINDS IN ADVANCE OF THE FRONT WILL LIKELY BE VERY CLOSE TO ADVISORY CRITERIA THIS EVENING. PLAN TO ISSUE WIND ADVISORY WITH THIS FORECAST PACKAGE...MAINLY FOR GUSTS NEAR 45 MPH WHICH MAY BE ENHANCED BY PRECIPITATION OF A CONVECTIVE CHARACTER. INDIRECT EFFECT OF THESE STRONG WIND FIELDS WILL BE ON CONVECTIVE POTENTIAL. 850 MB WINDS ARE FORECAST BY THE RUC MODEL TO INCREASE TO 50 TO 60 KT ACROSS WESTERN KENTUCKY BY MID EVENING. INTENSE FORCING ASSOCIATED WITH THE APPROACHING COLD FRONT AND SHORTWAVE MAY RESULT IN A STRONGLY FORCED LINE OF LOW TOPPED CONVECTION. THE PRIMARY LIMITING FACTORS ARE MOISTURE AND INSTABILITY. AN EASTERLY COMPONENT TO THE SURFACE WINDS IS IMPEDING THE NORTHWARD PROGRESS OF 60 DEGREE DEW POINTS THROUGH THE ARKLATEX REGION. RUC MODEL PINCHES OFF THE NARROW RIBBON OF 55 PLUS DEW POINTS BEFORE IT REACHES THE FORECAST AREA. THIS SUGGESTS THE PRIMARY HAZARD WILL BE A FEW DAMAGING WIND GUSTS WITH LOW TOPPED LINEAR STRUCTURES...PER 16Z SPC DAY 1 OUTLOOK. THE STRONG COLD FRONT WILL CROSS MOST OF THE FORECAST AREA AROUND 06Z...A COUPLE HOURS SOONER IN THE WEST AND LATER IN THE EAST. THIS FRONT WILL END THE BULK OF THE PRECIPITATION. SOME LINGERING POST FRONTAL STRATIFORM PRECIP IS POSSIBLE LATE TONIGHT...WHICH MAY END AS A BRIEF PERIOD OF SNOW IN PARTS OF SRN ILLINOIS AND SE MISSOURI. A SOLID LOW OVERCAST IN THE WAKE OF THE DEPARTING LOW PRESSURE CENTER WILL PERSIST INTO EARLY SUNDAY. MODELS ARE IN GOOD AGREEMENT THAT 925/850 MB RH WILL DECREASE SHARPLY AROUND 12Z IN SE MISSOURI...AND BY 18Z IN SOUTHWEST INDIANA AND PENNYRILE OF WEST KENTUCKY. A GUSTY WEST WIND AND STRONG COLD ADVECTION WILL PRODUCE WIND CHILLS IN THE 20S...IN SHARP CONTRAST TO TODAY. MONDAY THROUGH CHRISTMAS DAY WILL BE A SHORT LIVED QUIET PERIOD BEFORE AN ACTIVE PATTERN PATTERN RESUMES...AS DISCUSSED IN LONG TERM SEGMENT OF THIS DISCUSSION. LOW POPS FOR CHRISTMAS EVE/EARLY CHRISTMAS DAY WILL BE CONVERTED TO MENTION OF FLURRIES. A WEAK 500 MB SHORTWAVE WILL SHEAR APART AS IT CROSSES THE FORECAST AREA MONDAY NIGHT. SURFACE HIGH PRESSURE WILL MAINTAIN PLENTY OF DRY AIR...INHIBITING ANYTHING MORE THAN A TRACE EVENT. && .LONG TERM... ERY PROGRESSIVE UPPER FLOW REGIME WILL BRING NEXT SYSTEM IN QUICKLY DURING THE DAY WED AND WED NIGHT. WITH SFC LOW EXPECTED TO PASS NEAR OR JUST NORTH OF THE REGION...SHOULD STAY JUST WARM ENOUGH TO KEEP MOST OF THE SIGNIFICANT PRECIP IN THE LIQUID FORM. STILL WILL ALLOW FOR THE POSSIBILITY OF A CHANGE OVER TO SNOW OR A MIX OF RAIN AND SNOW ALONG AND NW OF THE OHIO RIVER WED NIGHT BEFORE THE PRECIP ENDS. 12Z GFS IS MUCH QUICKER WITH THE SYSTEM THAN IT HAS BEEN THE PAST SEVERAL RUNS. DECIDED TO DISCARD THIS QUICKER SOLUTION FOR THIS PACKAGE...AND WENT A LITTLE CLOSER TO THE MORE CONSISTENT AND SLOWER ECMWF SOLUTION. ALSO...THE ECMWF HAS BEEN THE BETTER MEDIUM RANGE PERFORMER AS OF LATE. 12Z GFS ALSO HAS COMPLETELY DIGRESSED FROM ITS PREVIOUS SOLUTION YESTERDAY OF BRINGING THE NEXT H50 SHORT WAVE INTO THE PLAINS FRI... OPTING TO KEEP THE UPPER SYSTEM OUT WEST. AGAIN...PREFER TO STICK WITH A SOLUTION CLOSER TO THE ECMWF HERE...WHICH CORRESPONDS CLOSELY TO WHAT WE HAVE ONGOING IN THE CURRENT FORECAST PACKAGE. IN FACT...IF THE 00Z ECMWF TURNS OUT CLOSE TO REALITY...WE WILL BE LOOKING AT A VERY POTENT SYSTEM COMING IN FRIDAY WITH EVEN A POSSIBILITY OF SOME SEVERE WEATHER. OF COURSE...MANY THINGS COULD CHANGE BY THAT TIME. WILL STAY FAIRLY CLOSE TO THE MEX MOS TEMPS IN THE WED THROUGH SAT TIME FRAME. && .AVIATION... SHOWERS AND EMBEDDED CONVECTION WILL MOVE RAPIDLY NORTHEAST ACROSS THE TAF SITES THIS EVENING. VERY STRONG LOW LEVEL WIND FIELDS WILL POSE A CONCERN FOR AVIATION. SURFACE GUSTS TO AROUND 30 KT WILL OCCUR PRIOR TO THE WIND SHIFT WITH THE COLD FRONT. WINDS ALOFT WILL BE NEAR 50 KT AT 3K FEET. FOLLOWING THE FRONTAL PASSAGE...WINDS ALOFT WILL DIMINISH SOMEWHAT TO AROUND 40 KT. HOWEVER...SURFACE GUSTS WILL REMAIN AROUND 30 KT. CIGS AND VSBYS WILL BE HIGHLY VARIABLE IN CONVECTIVE PRECIP THIS EVENING. FOLLOWING THE FRONTAL PASSAGE...A STABLE MVFR CIG IS EXPECTED...WITH VSBYS BECOMING EXCELLENT. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...WIND ADVISORY THROUGH 15Z FOR WEST KY. MO...WIND ADVISORY THROUGH 15Z FOR SE MISSOURI. IL...WIND ADVISORY THROUGH 15Z FOR S IL. IN...WIND ADVISORY THROUGH 15Z FOR SW IN. && $$ SHORT TERM...MY LONG TERM...GM AVIATION...MY ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 524 PM EST SAT DEC 22 2007 .DISCUSSION... SHORT TERM TO 00Z MON... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR WINTER STORM TONIGHT AND SUNDAY. WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER NORTH DAKOTA EMBEDDED IN A LONGWAVE TROUGH THAT STRETCHES FROM NORTHERN MANITOBA TO TEXAS. WEAK SHORTWAVE EJECTED OUT OF THE BASE OF THIS TROUGH ARE MOVING THROUGH THE FORECAST AREA. A LITTLE STRONGER SHORTWAVES ARE OVER OKLAHOMA AND OVER EASTERN NORTH DAKOTA ACCOMPANYING THE CLOSED LOW. SURFACE ANALYSIS DEPICTS A LOW OVER WESTERN LAKE SUPERIOR AND OVER SOUTHWEST MISSOURI. THESE LOW ARE LINKED BY A COLD FRONT. WARM MOISTURE AIR ARE DRAWN NORTH INTO THE UPPER GREAT LAKES REGION AHEAD OF THIS SYSTEM BY THE CYCLONIC FLOW. SURFACE DEW POINTS ARE WELL INTO THE MID 30S ACROSS THE AREA. THIS CONTINUES TO GENERATE RAIN...DRIZZLE AND FOG AROUND THE AREA. THE MID LEVEL LOW WILL DIVE SOUTH FROM NORTH DAKOTA INTO NORTHWEST IOWA TONIGHT. WHILE THE TWO SURFACE LOW MERGE OVERNIGHT NEAR KGRB. WARM MOIST AIR WILL CONTINUE TO BE DRAWN INTO THE AREA. ISENTROPIC ASCENT AHEAD OF THE FRONT WILL CONTINUE TO GENERATE PRECIPITATION ACROSS THE AREA. NAM/GFS FORECAST SOUNDINGS INDICATE THAT TEMPERATURES WILL STAY ABOVE FREEZING FROM SURFACE TO 850MB OVER THE EASTERN TWO THIRDS OF THE FORECAST AREA TONIGHT. A THERMAL TROUGH BEHIND THE FRONT WILL EDGE INTO MINNESOTA AND WISCONSIN OVERNIGHT. THE SURFACE LOW WILL SHIFT NORTHWARD INTO CENTRAL U.P. BY SUNSET SUNDAY. TIGHTER GRADIENTS BEHIND THE LOW WILL CAUSE STRONG WINDS OVER LAKE SUPERIOR AND EXPOSED AREA ALONG THE LAKE SUPERIOR SHORE. WRAP AROUND MOISTURE WILL SPREAD OVER THE AREA EARLY ON SUNDAY AND COLD AIR BEHIND THE LOW AND FRONT WILL CHANGE THE RAIN TO SNOW. 850MB DELTA-T`S WILL INCREASE TO AROUND 9C OVER THE WEST. EXPECT HEAVIEST SNOWFALL AMOUNTS OVER THE WESTERN U.P. DUE TO LAKE ENHANCED CONDITIONS. LONGER TERM...00Z MON ONWARD... NAM SHOWING THE CLOSED 500 MB LOW OVER SE LOWER MI 00Z MON THAT HEADS TO WESTERN QUE 12Z MON. THE UPPER LEVEL TROUGH MOVES EAST ON MON THEN WITH A WEAK SHORTWAVE ON THE BACKSIDE OF THE TROUGH AFFECTING THE CWA ON MON. UPPER LEVEL RIDGING THEN MOVES IN FOR MON NIGHT. THE NAM IS SHOWING 850-500 MB Q-VECTOR CONVERGENCE MOVING OUT SUN NIGHT WITH MOISTURE ALSO BEGINNING TO MOVE OUT. WEAK 850-500 MB Q-VECTOR CONVERGENCE MOVES BACK IN FOR MON AFTERNOON WITH THE SHORTWAVE ON THE BACKSIDE OF THE TROUGH...BUT DEEP MOISTURE BY THAT TIME IS GONE. SUN NIGHT...NAM IS SHOWING ISENTROPIC LIFT STILL ON THE BACKSIDE OF THE SYSTEM COMING IN FROM THE NE ON I280K-I295K SURFACES WITH WEAK BROADSCALE LIFT AT 06Z MON WITH MOISTURE STILL IN THE AREA BEFORE THE MOISTURE MOVES OUT AFTER 12Z MON. GFS SHOWS ABOUT THE SAME THING FOR Q-VECTOR CONVERGENCE AS WELL. WILL USE A BLEND OF THE TWO FOR THIS FORECAST. SUNDAY NIGHT WILL BE A PROBLEM OVER THE EASTERN CWA. DECIDED TO GO WITH A WATCH AT THIS POINT SINCE IT WILL BE NASTY AND IT IS CHRISTMAS TRAVELING SEASON. NOT SURE IF ADVISORY CRITERIA WILL EVEN BE MET OVER THE EAST OR EVEN WARNING CRITERIA AND NORMALLY WOULD NOT ISSUE A WATCH FOR THIS SITUATION...BUT WANT TO GET TRAVELERS A HEADS UP IT WILL BE BAD WITH SNOW AND BLOWING SNOW OVER THE ERN CWA WITH STRONGER WINDS OVER THE EAST SUN NIGHT. THAT IS THE REASON FOR A WATCH AT THIS TIME OVER THE ERN CWA. LATER SHIFTS CAN GO WITH WARNINGS OR ADVISORIES WHEN THEY ARE NEEDED OVER THE EAST. SUN NIGHT...SYNOPTIC SNOW WILL BE WINDING DOWN AND WILL BE REPLACED BY LAKE EFFECT OR LAKE ENHANCEMENT. COULD BE UP TO 5 INCHES OF SNOW POSSIBLE THEN WITH THE HEAVIEST SNOW IN THE EVENING. 850 MB TEMPERATURES GET DOWN TO ABOUT -8 TO -10C...BUT DEEP MOISTURE IS GONE BY THAT TIME. WILL CONTINUE THE WARNINGS IN THE WEST HALF TO 12Z MON FOR THIS REASON WITH A BIT OF BLOWING AND DRIFTING SNOW THEN TOO. MONDAY...LAKE EFFECT WINDS DOWN AS DRIER AIR ENTERS INTO THE AREA. OVERALL...DID NOT MAKE TOO MANY DRASTIC CHANGES TO THE GOING FORECAST FOR TEMPERATURES OR WEATHER. IN THE EXTENDED...00Z ECMWF WHICH WILL BE THE MODEL OF CHOICE TODAY HAS A TROUGH AFFECTING THE CWA WED AND THU WITH RIDGING FOR FRI AND ANOTHER POTENTIAL LARGE STORM FOR SAT WITH A CLOSED 500 MB LOW MOVING FROM THE 4 CORNERS REGION TO THE AREA FOR SAT. DID NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST EXCEPT TO GO DRY FOR LATE THU NIGHT THROUGH FRI AS SFC RIDGING MOVES IN AND SNOW MOVES IN FOR FRI NIGHT AND SAT. THIS SYSTEM WILL HAVE TO BE WATCHED AS IT IS A FOUR CORNERS LOW AND COMES UP OUR WAY WITH PLENTY OF MOISTURE AVAILABLE. THIS COULD BE THE NEXT BIG STORM...BUT TOO FAR OUT TO REALLY WORRY ABOUT YET AS THINGS COULD CHANGE. KEPT PRETTY CLOSE TO GOING TEMPERATURES. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... AVIATION FORECASTS ARE A LITTLE TRICKY...PRIMARILY AT CMX. THERE IS ALSO A 100 FT BROKEN DECK AT THE SITE...WHICH WITH THE EAST WIND...HAVE DECIDED TO INCLUDE A TEMPO FOR A IFR DECK. VSBYS AND CEILINGS CONTINUING LIFR THIS EVENING STILL LOOKS GOOD...AND WITH PLENTY OF MOISTURE/RAIN AROUND ASSOCIATED WITH LOW PRESSURE LIFTING NORTH FROM MISSOURI TOWARDS GREEN BAY...CANNOT IMAGINE CONDITIONS GETTING ANY BETTER AT CMX. RAIN SHOULD CHANGE OVER TO SNOW AT CMX LATE TONIGHT. AT SAW...SE WINDS ARE EXPECTED THROUGH THE ENTIRE PERIOD...RESULTING IN UPSLOPE FLOW WHICH SHOULD HELP HOLD CEILINGS AT LIFR. AS FAR AS VSBYS GO...CURRENT LIFR READINGS SHOULD BE ABLE TO HOLD THROUGH THE AFTERNOON THANKS TO SNOWMELT MAINTAINING FOG. HOWEVER...THE TYPICAL DIURNAL VARIATION COULD ALLOW VSBYS TO CLIMB TO IFR FOR SOME OF THIS AFTERNOON. A STEADY RAIN DEVELOPING TONIGHT SHOULD ONLY HELP TO KEEP CEILINGS LOW...BUT THERE IS SOME CONCERN FOR VSBYS TO RISE. WILL BANK ON SNOWMELT TO HELP KEEP VSBYS LOW. AS COOLER AIR ENTERS THE AREA EARLY SUNDAY MORNING THE RAIN SHOULD GRADUALLY CHANGE TO SNOW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... AFTER A GENERAL QUIET PERIOD ON LAKE SUPERIOR THROUGH TONIGHT WITH WINDS NO HIGHER THAN 25 KT (GREATEST NEAR WHITEFISH POINT)...WINDS WILL REALLY INCREASE ON SUNDAY. THIS RAPID INCREASE IS DUE TO LOW PRESSURE OVER SOUTHERN MISSOURI THIS EVENING THAT RAPIDLY DEEPENS AS IT HEADS DUE NORTH TOWARD CENTRAL UPPER MICHIGAN. AS THE LOW MOVES TO NEAR MARQUETTE EARLY SUNDAY AFTERNOON...NORTH TO NORTHEAST WINDS ACROSS WESTERN LAKE SUPERIOR SHOULD INCREASE TO GALES. AS THE LOW SHIFTS FROM NEAR MUNISING SUNDAY EVENING INTO NORTHWEST QUEBEC LATE IN THE NIGHT...WINDS WILL QUICKLY RELAX...DROPPING BELOW GALES ACROSS ALL OF LAKE SUPERIOR JUST AFTER MIDNIGHT SUNDAY NIGHT. WINDS BELOW 30 KT ARE THEN EXPECTED FOR CHRISTMAS EVE INTO WEDNESDAY...WITH A HIGH PRESSURE RIDGE CROSSING MONDAY NIGHT AND A LOW PRESSURE TROUGH CROSSING TUESDAY NIGHT. ANOTHER LOW WITH AN ACCOMPANYING FRONTAL SYSTEM WILL SHIFT ACROSS THE AREA ON WEDNESDAY. WINDS WILL PICK UP BEHIND THE LOW ON WEDNESDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN...HEAVY SNOW WARNING FROM 1 AM EST /MIDNIGHT CST/ SUNDAY TO 7 AM EST /6 AM CST/ MONDAY FOR MIZ002-004-005-009-010-084. WINTER STORM WATCH FROM SUNDAY EVENING THROUGH MONDAY MORNING FOR MIZ006-007-014-085. WINTER STORM WARNING FROM 1 AM SUNDAY TO 7 AM EST MONDAY FOR MIZ001-003. HEAVY SNOW WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST SUNDAY FOR MIZ011. LAKE SUPERIOR...GALE WARNING FROM 7 PM SUNDAY TO 5 AM EST MONDAY FOR LSZ266-267. GALE WARNING FROM 7 PM SUNDAY TO 3 AM EST MONDAY FOR LSZ265. GALE WARNING FROM 11 AM SUNDAY TO 5 AM EST MONDAY FOR LSZ264. GALE WARNING FROM 7 PM SUNDAY TO 1 AM EST MONDAY FOR LSZ245. GALE WARNING FROM 5 PM SUNDAY TO 1 AM EST MONDAY FOR LSZ242>244. GALE WARNING FROM 11 AM SUNDAY TO 3 AM EST MONDAY FOR LSZ263. GALE WARNING FROM 10 AM SUNDAY TO 9 PM CST SUNDAY FOR LSZ162. LAKE MICHIGAN...GALE WARNING FROM 1 PM TO 8 PM EST SUNDAY FOR LMZ221-248-250. && $$ SHORT TERM/AVIATION/MARINE...DLG LONG TERM...GJM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 139 PM EST SAT DEC 22 2007 LATEST UPDATE...AVIATION... .SYNOPSIS...(358 AM EST SAT DEC 22 2007) THE BIG STORY THIS WEEKEND WILL BE THE APPROACH AND PASSAGE OF A LOW PRESSURE SYSTEM. AHEAD OF THE LOW WE/LL SEE FOG AND DRIZZLE TODAY... WITH A FEW SHOWERS POSSIBLE TOO...AND THEN WINDY CONDITIONS SUNDAY MORNING AS THE LOW MOVES NORTH THROUGH LOWER MICHIGAN AND A COLD FRONT MOVES BY. MUCH COLDER AIR WILL THEN FLOW ACROSS THE STATE AND LAKE EFFECT SNOW SHOWERS WILL DEVELOP. THE POTENTIAL FOR STRONG WINDS EXISTS WITH GUSTS TO 50 MPH. THAT MEANS THE SNOW WILL BLOW AND DRIFT QUITE A BIT. && .SHORT TERM...(1132 AM EST SAT DEC 22 2007) FOR THE MOST PART THE FOG IS EITHER LIFTING OR WILL BE LIFTING. AS A RESULT I HAVE PULLED THE FOG OUT OF THE FORECAST FOR THIS AFTERNOON AND TONIGHT FOR ALL BUT THE EXTREME NORTH. THE LATEST MODEL DATA (RUC AND NAM) PLUS VAD WIND PROFILES AND TAMDAR DATA SUGGEST BOUNDARY LAYER WINDS WILL BE NEAR 35 KNOTS THIS AFTERNOON. AT 14Z TAMDAR SHOWED 44 KNOTS OVER GRR AROUND 4900 AGL. THAT SHOULD INDUCE ENOUGH MIXING TO KEEP THE FOG FROM REALLY BEING AN ISSUE OVER MOST OF THE CWA EVEN WITH THE SNOW MELT AND 45F DEW POINTS TO OUR SOUTH HEADING OUR WAY. FOR THOSE REASONS I SIGNIFICANTLY INCREASED OUR FORECAST HIGH TODAY TO BETWEEN 45 AND 50 OVER ALL BUT THE NORTHERN CWA. FOR THE MOST PART IT WILL JUST BE CLOUDY UNTIL THE FRONTAL PRECIPITATION BAND MOVES ACROSS THE CWA AFTER 3 AM. ONE OTHER THOUGH...I NOW BELIEVE WE WILL NOT SEEM MUCH SNOW DURING THE DAY TIME OF SUNDAY. IT WILL TAKE UNTIL THE NEXT SHORTWAVE ROTATING AROUND THE UPPER LOW MOVES IN SUNDAY EVENING TO GET THE SNOW SHOWERS GOING. THIS WOULD LEAD TO A WIND ADVISORY SUNDAY AND A SNOW AND BLOWING SNOW ADVISORY SUNDAY NIGHT. HOWEVER... AT THIS POINT NOT WANTING TO HAVE TWO HEADLINES OUT...AND NOT BEING TOTALLY SURE OF THIS ANYWAY...MORE THAN LIKELY I WILL LET OUR HEADLINES STAND AS IS THEY ARE FOR THE 4 PM FORECAST UPDATE. THE MIDNIGHT SHIFT CAN MAKE THE FINAL DECISION AS TO WHAT HEADLINE TO ACTUALLY GO WITH. PREVIOUS DISSUASION...IT/S NOT OUT OF THE QUESTION THAT WE MAY SEE A THUNDERSTORM JUST AHEAD OF THE FRONT EARLY SUNDAY MORNING... ESPECIALLY OVER THE SOUTHERN CWA. ELEVATED LI/S FALL JUST BELOW 0C AND THETA-E DECREASES WITH HEIGHT. BUT I THINK THE CHANCE IS SMALL ENOUGH TO LEAVE OUT OF THE GRIDS ATTM. THE ARCTIC FRONT WILL SLAM THROUGH EARLY SUNDAY. RAIN WILL QUICKLY CHANGE OVER TO SNOW SHOWERS/SQUALLS AS H8 TEMPS AROUND -15C MOVE THROUGH. WINDS IN THE BOUNDARY LAYER WILL BE IN THE 55 KT RANGE AND SOME OF THIS WILL GET PULLED TO THE GROUND. WITH THE STRONG WINDS THAT ARE EXPECTED...WE/LL SEE A VERY CELLULAR APPEARANCE TO THE SNOW. IT WILL ALSO BLOW ACROSS THE ENTIRE CWA. THE WSW FLOW WILL FAVOR THE CENTRAL CWA ALONG THE US131 CORRIDOR. GOING ACCUMS IN THE GRIDS LOOK OK AT THIS POINT. THERE ARE A COUPLE OF THINGS GOING FOR THIS SYSTEM. FIRST IS THAT IT WILL BE INTENSIFYING AS IT MOVES ACROSS THE STATE. SECOND IS THE STRONG UPPER SUPPORT. SEVERAL STRONG SHORT WAVES ARE PROGGED TO MOVE THROUGH THE CWA SUNDAY AND SUNDAY NIGHT WHICH WILL HELP SNOWFALL RATES. SECOND IS THE DEEP SNOW GROWTH REGION LATE SUNDAY WITH AN OMEGA BULLSEYE IN IT. COUPLED WITH THE LAKE INSTABILITY...WE COULD SEE ACCUMS IN THE 6-8 INCH RANGE ACROSS THE CENTRAL CWA...ALTHOUGH IT/S GOING TO BE DIFFICULT TO MEASURE WITH THE STRONG WIND. WE/LL KEEP THE WATCH GOING AT THIS POINT. GFS SHOWS CYCLONIC CURVATURE OVER LOWER MICHIGAN THROUGH MONDAY ALTHOUGH THE MAIN LOW WILL BE OVER NEW ENGLAND BY THEN. SHSN WILL BEGIN TO WIND DOWN BY LATE IN THE DAY AS H8 TEMPS WARM TO -7C OVER THE LAKE. && .LONG TERM...(358 AM EST SAT DEC 22 2007) LAKE EFFECT SNOW SHOWERS SHOULD DIMINISH/END ON CHRISTMAS EVE AND QUIET WEATHER IS ANTICIPATED FOR CHRISTMAS DAY AS A RIDGE OF HIGH PRESSURE IMPACTS THE REGION. THE NEXT FEATURE OF INTEREST IS A TROUGH WHICH ENTERS THE PICTURE FOR WEDNESDAY NIGHT AND THURSDAY. CURRENTLY IT APPEARS THAT AN ELONGATED N-S SURFACE TROUGH WILL CROSS THE REGION AND BRING SOME SCATTERED SNOW SHOWERS. HOWEVER THE POTENTIAL EXISTS FOR A STRONG SRN STREAM SHORTWAVE TO HEAD NORTHEAST FROM THE SRN PLAINS/GULF COAST REGION AND SPIN UP A DECENT SURFACE LOW WHICH COULD PASS THROUGH THE OHIO VALLEY. THIS SCENARIO COULD LEAD TO A SIGNIFICANT SNOW EVENT...BUT MODELS ARE NOT IN VERY GOOD AGREEMENT ON HOW THIS WILL PLAY OUT ATTM. CURRENT INDICATIONS ARE THAT DEEP H5 LONGWAVE TROUGHING WILL PERSIST EAST OF THE ROCKIES DURING THE LATE WEEK PERIOD. THIS PATTERN MAY ALLOW ANOTHER CYCLONE OR TWO TO TRACK SW TO NE THROUGH THE REGION AND BRING A THREAT OF RAIN OR SNOW. && .AVIATION...(139 PM EST SAT DEC 22 2007) WIDESPREAD IFR/MVFR IN STRATUS/FOG WILL CONTINUE THROUGH THE DAY CONDITIONS WILL FALL BACK TO IFR/LIFR TONIGHT. RAIN SHOWERS WILL BECOME WIDESPREAD/STEADIER AFTER MIDNIGHT TONIGHT AND THAT SHOULD LIMIT THE THREAT/EXTENT OF THE DENSE FOG FROM LAST NIGHT. THE RAIN SHOULD CONTINUE INTO THE DAY. && .MARINE...(1132 AM EST SAT DEC 22 2007) WE MAY NEED A STORM WARNING OVER THE SOUTHERN NEAR SHORE AREAS SUNDAY EVENING AS BOTH THE RUC13 AND LOCAL WAF SHOW 50 KNOT SURFACE WINDS OVER THE SOUTHEAST 1/3 OF THE LAKE. PROBLEM THERE THOUGH IS THE NAM 12Z RUN SHOWS ONLY 45 KNOTS OVER MID LAKE TO MIX DOWN AT THAT TIME. SO FOR NOW I WILL NOT CHANGE THE HEADLINES BUT WILL CONSIDER AND UPGRADE WITH THE 4 PM MARINE FORECAST. HAVING A NEARLY 20 MB PRESSURE DIFFERENCE BETWEEN ORD AND TVC AT 00Z MONDAY IS SOMETHING ONE NEEDS TO CONSIDER! && .HYDROLOGY...(1132 AM EST SAT DEC 22 2007) NO SIGNIFICANT HYDRO ISSUES ARE ANTICIPATED. A QUICK CHECK OF OUR RIVERS AT 15Z SHOWS THEY ARE FOR THE MOST PART STEADY AND SHOWING NO SIGNIFICANT RISES. THEY ARE ALSO ALL SIGNIFICANTLY BELOW ACTION STAGE. WE HAVE SOME INDICATIONS OF RIVER ICE IN PLACES BUT WITH THIS SLOW WARM UP BEFORE THE RAIN COMES...AND WITH THE QPF BEING A HALF INCH OR LESS WITH THE RAIN PART OF THIS SYSTEM PLUS CONSIDERING THAT WHAT IS RUNNING OFF WILL QUICKLY FREEZE SUNDAY ANYWAY I BELIEVE WE DO NOT HAVE TO WORRY TO MUCH ABOUT ANY HYDRO HAZARDS. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...A WINTER STORM WATCH IS IN EFFECT FROM 16Z SUNDAY THROUGH 12Z MONDAY FOR ALL BUT THE EASTERN AND SOUTHERN ROW OF SOUTHWEST LOWER MICHIGAN. LM...SMALL CRAFT ADVISORY IN EFFECT TODAY AND TONIGHT ENTIRE NEARSHORE. A GALE WATCH IS IN EFFECT FROM SUNDAY AND SUNDAY NIGHT ENTIRE NEARSHORE. && $$ SYNOPSIS: 93 SHORT TERM: WDM LONG TERM: MEADE AVIATION: MEADE MARINE: WDM HYDROLOGY: WDM mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1224 PM EST SAT DEC 22 2007 ,,,UPDATE FOR AVIATION... .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE POTENTIAL FOR AND FOG THIS AFTERNOON... .SYNOPSIS...WATER VAPOR IMAGERY AND RUC SHOWING TWO CLOSED LOW EMBEDDED IN A LONGWAVE TROUGH OVER MID SECTION OF CONUS. ONE OF THE LOWS IS OVER NORTH CENTRAL NORTH DAKOTA AND THE OTHER IS OVER THE TEXAS PANHANDLE. WEAK SHORTWAVES BEING EJECTED OUT OF THIS SYSTEM ARE OVER IOWA AND OVER LAKE SUPERIOR. SURFACE ANALYSIS DEPICTS A LOW OVER EASTERN OKLAHOMA AND A LOW OVER WESTERN ONTARIO WITH A COLD FRONT EXTENDING BETWEEN THE TWO LOWS. A LARGE HIGH OVER MIDDLE HIGH PLAINS IS PUSHING THE FRONTAL SYSTEM EAST. THE FLOW AHEAD OF THE FRONTAL SYSTEM IS DRAWING DEEP MOISTURE AND WARM AIR FROM THE GULF NORTHWARD INTO THE UPPER GREAT LAKES REGION. ISENTROPIC ASCENT AHEAD OF THE SYSTEM CONTINUES TO PRODUCE RAINS OVER THE AREA. KMQT-88D SHOWING SEVERAL BANDS OF RAIN MOVING THROUGH THE FORECAST AREA. LOW LEVEL MOISTURE AND SURFACE BASED INVERSION AND LIGHT WINDS HAVE PRODUCE CONSIDERABLE FOG AROUND THE AREA THIS MORNING. .SHORT TERM...TODAY... THE MID LEVEL LOW OVER NORTH DAKOTA WILL SHIFT TO EAST CENTRAL NORTH DAKOTA TODAY...WHILE THE TEXAS LOW LIFTS NORTHEAST INTO SOUTHEAST KANSAS. THE ONTARIO SURFACE LOW WILL SETTLE SOUTH INTO WESTERN LAKE SUPERIOR WHILE THE OKLAHOMA LOW MOVES INTO SOUTHERN MISSOURI. THE FRONTAL SYSTEM WILL CONTINUE TO DRAW MORE DEEP MOISTURE INTO THE REGION AHEAD OF IT. AREAS OF RAIN WILL CONTINUE OVER THE AREA TODAY AS WEAK SHORTWAVES SHIFT INTO THE AREA AND ISENTROPIC ASCENT PREVAIL OVER THE AREA THIS AFTERNOON. LONG TERM...TONIGHT AND LATER... FOR TNGT...NAM/GFS IN EXCELLENT AGREEMENT SHOWING DETAILS OF PHASING BRANCHES...WITH RDPLY DEEPENING LO PRES MOVING TO NEAR GRB BY 12Z SUN. INCRSG UPR DIFFLUENCE/H5 HGT FALLS/DEEP LYR QVECTOR CNVGC TO THE NE OF DVLPG NEGATIVELY TILTED CUTOFF LO AT H5 JUST TO THE SW OF MPX ESPECIALLY AFT 06Z WL SUPPORT INCRSGLY WDSPRD PCPN. TRACK OF SFC LO WL DRAW ENUF WARM AIR INTO THE ERN/NCNTRL FA TO MAINTAIN JUST RA... BUT OVER THE W THE COMBINATION OF INTENSE UVV/DYNAMIC COOLING AND INFLUX OF LLVL COLD AIR WL CAUSE THE PCPN TO BE SN OR CHG TO SN. USING NAM FCST WBZ HGT OF 1500FT/H925-85 THKNS OF 676M AS A GUIDE... LOOK FOR THE RA/SN LINE TO BE FM CMX-HURON MNTS-CRYSTAL FALLS OR SO BY 12Z SUN ON THE COLD SIDE OF THE H85 LO TRACK. ON SUN...SFC LO PROGGED TO MOVE TO SLOWLY TO ARND SCNTRL LK SUP BY LATE IN THE DAY AS UPR LO SLIDES INTO THE CNTRL GRT LKS...SUPPORTING 12HR H5 HGT FALLS UP TO 150M. PCPN WL GRDLY CHG TO SN WITH DYNAMIC COOLING...BUT WARM LYR ALF/TROWAL FEATURE WL RETARD CHGOVER NEAR LK SUP OVER THE NCNTRL...ESPECIALLY WITH N FLOW OFF THE WARM LK WATERS. IN FACT...THE PCPN MAY CHG TO SN FASTER OVER THE E AND NEAR LK MI THAN AT THE CITY OF MQT. OTRW...ARRIVAL OF HIER SPECIFIC HUMIDITY FM THE NNE TO THE W OF LO WL ENHANCE PCPN RATES ESPECIALLY WHERE LLVL NNE FLOW UPSLOPES AND WHERE CROSS SECTION SHOWS THETA-E DCRSG A BIT WITH HGT ABV TROWAL ACRS THE NCNTRL W OF MQT. WHERE THE PCPN FALLS AS SN...INCRSG WINDS WL CAUSE CONSIDERABLE BLSN. BUT FCST SCENARIO ATTM SEEMS TO SUG WINDS/BLSN WL NOT BE AS SGNFT AS PREVIOUSLY THOUGHT. SINCE THE HEAVIEST SN WL FALL ONLY LATE IN THE SECOND PD AND THE THIRD PD...OPTED TO KEEP GOING WATCH AND NOT UPGRADE TO WRNG...ESPECIALLY SINCE 06Z NAM APPEARS TO BE SLOWER BRINGING IN THE SHARPER DYNAMICS. EXPECT ANY PCPN TO BE ALL SN SUN NGT BUT THEN TO GRDLY DIMINISH AS HGTS RISE FAIRLY SHARPLY IN THE WAKE OF THE DEPARTING UPR LO WITH UPR CNVGC/DNVA/DEEP LYR QVECTOR DVGC. INCOMING AIRMASS DOES NOT APPEAR PARTICULARLY COLD (H85 TEMPS ARND -10C) EITHER WITH HIER MSTR TENDING ...SO LES SHOULD NOT GET OUT OF HAND. BUT PERSISTENT CYC FLOW WL CONT -SHSN THRU THE NGT ALBEIT AT A LIGHTER RATE. COORDINATED WITH APX/GRB/DLH. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... AVIATION FORECASTS ARE A LITTLE TRICKY...PRIMARILY AT CMX. THERE IS ALSO A 100 FT BROKEN DECK AT THE SITE...WHICH WITH THE EAST WIND...HAVE DECIDED TO INCLUDE A TEMPO FOR A IFR DECK. VSBYS AND CEILINGS CONTINUING LIFR THIS EVENING STILL LOOKS GOOD...AND WITH PLENTY OF MOISTURE/RAIN AROUND ASSOCIATED WITH LOW PRESSURE LIFTING NORTH FROM MISSOURI TOWARDS GREEN BAY...CANNOT IMAGINE CONDITIONS GETTING ANY BETTER AT CMX. RAIN SHOULD CHANGE OVER TO SNOW AT CMX LATE TONIGHT. AT SAW...SE WINDS ARE EXPECTED THROUGH THE ENTIRE PERIOD...RESULTING IN UPSLOPE FLOW WHICH SHOULD HELP HOLD CEILINGS AT LIFR. AS FAR AS VSBYS GO...CURRENT LIFR READINGS SHOULD BE ABLE TO HOLD THROUGH THE AFTERNOON THANKS TO SNOWMELT MAINTAINING FOG. HOWEVER...THE TYPICAL DIURNAL VARIATION COULD ALLOW VSBYS TO CLIMB TO IFR FOR SOME OF THIS AFTERNOON. A STEADY RAIN DEVELOPING TONIGHT SHOULD ONLY HELP TO KEEP CEILINGS LOW...BUT THERE IS SOME CONCERN FOR VSBYS TO RISE. WILL BANK ON SNOWMELT TO HELP KEEP VSBYS LOW. AS COOLER AIR ENTERS THE AREA EARLY SUNDAY MORNING THE RAIN SHOULD GRADUALLY CHANGE TO SNOW. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... AFTER A GENERAL QUIET PERIOD ON LAKE SUPERIOR THROUGH TONIGHT WITH WINDS NO HIGHER THAN 25 KT (GREATEST NEAR WHITEFISH POINT)...EXPECT WINDS TO REALLY INCREASE SUNDAY. THIS RAPID INCREASE IS DUE TO LOW PRESSURE OVER SOUTHERN MISSOURI THIS EVENING THAT RAPIDLY DEEPENS AS IT HEADS DUE NORTH TOWARD CENTRAL UPPER MICHIGAN. AS THE LOW MOVES TO NEAR MARQUETTE EARLY SUNDAY AFTERNOON...NORTH TO NORTHEAST WINDS ACROSS WESTERN LAKE SUPERIOR SHOULD INCREASE TO GALES. BY SUNDAY EVENING...THERE IS A CHANCE THEY COULD INCREASE TO STORM FORCE... ESPECIALLY NEAR ISLE ROYALE. AS THE LOW SHIFTS FROM NEAR MUNISING SUNDAY EVENING INTO NORTHWEST QUEBEC LATE IN THE NIGHT...WINDS WILL QUICKLY RELAX...DROPPING BELOW GALES ACROSS ALL OF LAKE SUPERIOR JUST AFTER MIDNIGHT SUNDAY NIGHT. WINDS BELOW 30 KT ARE THEN EXPECTED FOR CHRISTMAS EVE INTO WEDNESDAY...WITH A HIGH PRESSURE RIDGE CROSSING MONDAY NIGHT AND A LOW PRESSURE TROUGH CROSSING TUESDAY NIGHT. && .MQT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY MORNING FOR MIZ001>005-009-010-084. WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY AFTERNOON FOR MIZ011. && $$ SYNOPSIS AND SHORT TERM...DLG LONG TERM...KC AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 415 PM CST SAT DEC 22 2007 .DISCUSSION... FORECAST CONCERN TODAY IS FAIRLY OBVIOUS...WITH CYCLOGENESIS TAKING PLACE OVER THE MISSISSIPPI VALLEY AND SIGNIFICANT SNOWFALL EXPECTED OVER PORTIONS OF THE FORECAST AREA. LATEST WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES DEPICT A DEEP TROUGH OVER THE CENTRAL CONUS...WITH A SOUTHERN SHORTWAVE FEATURE LIFTING NORTHEAST FROM THE SOUTHERN PLAINS AS A VIGOROUS NORTHERN STREAM WAVE AND ASSOCIATED COLD POOL DIVE SOUTHEAST THROUGH THE DAKOTAS. THESE FEATURES WILL PHASE OVER THE NEXT 12-24 HOURS...WITH RAPID CYCLOGENESIS OCCURRING OVER THE MISSISSIPPI VALLEY...AND A DEEPENING MOVING NORTH TOWARD THE UPPER GREAT LAKES. THREE HOUR SEA LEVEL PRESSURE CHANGES HAVE INCREASED MARKEDLY OVER THE PAST FEW HOURS OVER THE MID AND SOUTHERN MISSISSIPPI VALLEY AND THIS TREND WILL CONTINUE THROUGH THE NIGHT AS THE CURRENT 1001 MB LOW DEEPENS TO AROUND 989 MB BY 12Z SUNDAY. THE 12Z GFS...NAM...ECMWF...AND SREFS ARE IN QUITE GOOD AGREEMENT ON THE EVOLUTION OF THE MAIN SURFACE AND UPPER AIR FEATURES THROUGH SUNDAY EVENING...SO A GENERAL BLEND OF THEIR GUIDANCE WAS USED FOR THE FORECAST. SNOWFALL HAS DEVELOPED QUITE RAPIDLY OVER IOWA THIS AFTERNOON...AND THIS AREA OF SNOW WILL MOVE NNE TONIGHT AS WARM ADVECTION SURGES NORTH ALONG WITH INCREASING UPPER DIVERGENCE IN THE LEFT EXIT REGION OF THE JET STREAK LIFTING NORTHEAST FROM THE LOWER MISSISSIPPI VALLEY. THERE WILL BE A VERY SHARP DEMARCATION IN THE AREA OF HEAVIER PCPN TONIGHT INTO SUNDAY MORNING...WITH MOISTURE AND FORCING DROPPING OFF SIGNIFICANTLY JUST WEST OF THE WISCONSIN BORDER. CONDENSATION PRESSURE DEFICITS AND ISENTROPIC UPGLIDE ON THE 290K SURFACE SHOW THIS FAIRLY WELL...AND EXPECT THE BEST CHANCES FOR SNOWFALL TONIGHT TO BE OVER THE FAR EASTERN CWFA. IN ADDITION TO THE ISENTROPIC ASCENT AND FORCING SUPPLIED BY UPPER LEVEL DIVERGENCE...SOME DECENT FRONTOGENESIS IN THE 700-750MB LAYER SHOULD HELP AUGMENT LIFT ACROSS THE EASTERN CWFA TONIGHT...AND THE NAM AND GFS BOTH SUGGEST THE PRESENCE OF SOME NEGATIVE EPV JUST ABOVE THIS LAYER...OWING PRIMARILY TO POTENTIAL INSTABILITY GIVEN THE NEARLY VERTICAL AND EVEN SLIGHTLY INVERTED THETA-E SURFACES ABOVE 650MB. IT APPEARS THERE WILL BE A GAP OR BRIEF LULL IN THE HEAVIER SNOWFALL AROUND 12Z ON SUNDAY AS THE INITIAL BURST OWING TO THE FACTORS MENTIONED ABOVE WANE FOR A BRIEF TIME AND THERE IS ACTUAL A PERIOD OF FAIRLY SUBSTANTIAL MID LEVEL FRONTOLYSIS AND SUBSIDENCE OVER THE EASTERN COUNTIES. HOWEVER...AS THE SURFACE LOW LIFTS TOWARD UPPER MICHIGAN LATER SUNDAY MORNING...THE MID LEVEL DEFORMATION ZONE AROUND THE BACK SIDE OF THE LOW WILL SWING BACK INTO THE FORECAST AREA...IMPACTING NOT ONLY THE EASTERN COUNTIES BUT ALSO A GOOD PART OF THE REMAINING FORECAST AREA. THE FAR SOUTHWEST WILL HAVE THE LEAST CHANCE OF SEEING ACCUMULATING SNOW ON SUNDAY...BUT A FEW INCHES COULD FALL OVER MUCH OF THE REMAINING AREA...INCLUDING THE TWIN CITIES. THERE WILL ACTUALLY BE SOME PERSISTENT...ALBEIT WEAK...UPGLIDE FROM THE NORTHEAST ON THE 290K SURFACE FOR MUCH OF THE DAY...WITH MUCH BETTER DEEP LAYER RH OVER THE ENTIRE AREA AS MOISTURE WRAPS AROUND THE BACK SIDE OF THE OCCLUDING SYSTEM. 650-700MB FRONTOGENESIS LOOKS LIKE IT WILL RE- ESTABLISH ITSELF IN THE DEFORMATION ZONE...ALTHOUGH ONCE AGAIN THIS FORCING MECHANISM LOOKS LIKE IT WILL AUGMENT THINGS BEST OVER THE EAST AND NORTHEAST COUNTIES. AS THE SYSTEM OCCLUDES AND SHIFTS FARTHER NORTHEAST SUNDAY NIGHT WE SHOULD FINALLY SEE THINGS SETTLE DOWN ACROSS THE ENTIRE FORECAST AREA. WINDS THROUGHOUT THE EVENT WILL BE QUITE STRONG...WITH THE GFS AND NAM BOTH SUGGESTING SOME 35-40KT WINDS IN THE MIXED LAYER...SO 20-30KT WINDS LATE TONIGHT THROUGH SUNDAY COULD GUST NEAR 40MPH AT TIMES...WHICH WILL DEFINITELY MAKE CONDITIONS WORSE THAN THEY WOULD BE FROM THE SNOWFALL ALONE. LOCATIONS THAT ONLY SEE A FEW INCHES WILL STILL EXPERIENCE SIGNIFICANTLY REDUCED VISIBILITIES AT TIMES GIVEN THE POTENTIAL FOR BLOWING SNOW. RIDGING WILL WORK INTO THE AREA BY MONDAY MORNING AND PERSIST INTO MONDAY NIGHT BEFORE RETURN FLOW SETS UP AGAIN LATE MONDAY NIGHT. A SHARP 500MB SHORTWAVE TROUGH AND ASSOCIATED WEAK FRONTAL BOUNDARY WILL SWING THROUGH ON TUESDAY...BRINGING A CHANCE FOR SOME MORE SNOWFALL...ALTHOUGH AT THIS POINT IT LOOKS LIKE THE WINDOW FOR MOISTURE RETURN AHEAD OF THIS FEATURE SHOULD KEEP PCPN AMOUNTS FAIRLY LOW. INCLUDED JUST CHANCE POPS TO HANDLE THINGS FOR NOW...BUT THESE WILL LIKELY NEED TO GET BUMPED UP AS THE TIMING BECOMES MORE CERTAIN. IN THE WEDNESDAY THROUGH SATURDAY TIME FRAME...THERE WAS A FAIR AMOUNT OF DISAGREEMENT AMONGST THE 00Z MODEL SOLUTIONS...AND STAYED FAIRLY CLOSE TO THE HPC PREFERRED SOLUTION...WHICH GENERALLY MIRRORED THE 00Z ECMWF. THE ECMWF KEPT THE BAROCLINIC ZONE FAIRLY CLOSE TO THE AREA WEDNESDAY THROUGH THURSDAY...SUGGESTING THE NEED TO KEEP SOME CHANCE POPS IN THE FORECAST THROUGH THAT TIME PERIOD. HOWEVER...IT DID BUILD ENOUGH RIDGING INTO THE STATE BY FRIDAY TO GO WITH A DRY FORECAST AT THAT POINT...BUT ITS DEVELOPMENT OF A SURFACE LOW AND ITS MOVEMENT BY TO OUR SOUTHEAST ON SATURDAY NECESSITATED THE MENTION OF A CHANCE OF SNOW AGAIN AT THAT POINT. THE 12Z ECMWF WAS A BIT MORE IN LINE WITH THE GFS...WHICH WOULD HAVE MORE IN THE WAY OF DRY WEATHER THROUGHOUT THE PERIOD...SO LATER FORECASTS WILL LIKELY NEED TO MAKE SOME ADJUSTMENTS AS THE THINGS MOVE CLOSER IN TIME. && .AVIATION.../18Z TAF ISSUANCE/ THE FIRST BATCH OF RAIN/SNOW WILL CONTINUE SHIFTING OFF TO THE NORTH/EAST OF MOST TAF SITES THIS AFTERNOON. -SN WILL LINGER AT THE BEGINNING OF THE PERIOD AT KRNH...WITH -RA EXPECTED TO CHANGE TO -SN AT KEAU BETWEEN 19Z AND 21Z. ATTENDANT MVFR CEILINGS WILL GRADUALLY SCATTER OUT AND IMPROVE TO THE VFR CATEGORY THIS AFTERNOON AT KSTC/KMSP...BUT PERSIST AT KRNH THROUGH THE AFTERNOON...AND AT KEAU THROUGH TONIGHT. LOW CLOUDS WILL BUILD BACK INTO THE REMAINDER OF TAF SITES TONIGHT...AS MOISTURE WRAPS AROUND THE BACK SIDE OF THE LOW. SNOW SHOWERS WILL PERSIST AT KEAU OVERNIGHT...AND WORK BACK WESTWARD TOWARD KRNH/KMSP ON SUNDAY MORNING. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...WINTER STORM WARNING UNTIL MIDNIGHT CST SUNDAY NIGHT FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-POLK-RUSK. && $$ mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 1250 PM CST SAT DEC 22 2007 .MESOSCALE UPDATE...BAND OF STORMS ACROSS CENTRAL AR/WESTERN LA/SE TX HAS INTENSIFIED OVER THE LAST HOUR. AM GUESSING THAT THE RUC MAY BE UNDERESTIMATING THE AMOUNT OF ELEVATED INSTABILITY AVAILABLE GIVEN THE STEADY INTENSIFICATION...MORE AGGRESSIVE NAM/GFS PROBABLY MORE REASONABLE. IN ANY EVENT...EXPECT THAT CONTINUED STRONG THERMAL/MOIST ADVECTION JUST ABOVE THE SURFACE WILL CONTINUE TO KEEP STORMS GOING AS THEY MOVE INTO THE WESTERN PART OF OUR AREA IN A COUPLE OF HOURS. LARGE BREAKS IN THE LOW CLOUDS HAVE EXPANDED ACROSS NE LA AND WESTERN MS...AND INSOLATION SHOULD WARM THE BOUNDARY LAYER AND ENHANCE THE POSSIBILITY OF STRONG CONVECTIVE WINDS MAKING IT DOWN TO THE SURFACE. STILL EXPECT THAT THE GREATEST RISK OF ANY SEVERE STORMS WILL BE WEST OF I-55 BETWEEN 3 AND 9 PM...AND THAT DAMAGING WINDS WILL BE THE PRIMARY THREAT. SPC HAS ISSUED A MESOSCALE DISCUSSION FOR THIS AREA...AND A SVR TSTM WATCH MAY COME OUT IN THE NEXT HOUR OR TWO FOR THIS AREA. THANKS AGAIN TO SPC FOR ADDITIONAL COORDINATION. && .AVIATION...EXPECT AT LEAST BKN LOW CLOUDS AT MOST LOCATIONS THROUGH THE AFTERNOON WITH A MAINTENANCE OF GENERALLY MVFR CONDITIONS. OCCASIONAL SCT CONDITIONS COULD OCCUR THOUGH AS LARGE BREAKS CURRENTLY ON SATELLITE IN WRN MS. WILL TIME SHRA/TSRA THREAT IN TAFS BASED ON EXPECTED TIMING OF CONVECTIVE LINE. CLOUDS WILL LINGER TONIGHT AFTER FROPA...BUT EXPECT RAPID CLEARING BY SUN AM. && .JAN WATCHES/WARNINGS/ADVISORIES... MS...LAKE WIND ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR MSZ018- 019-025>038-040>044-047>049-053-059-060. LA...LAKE WIND ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR LAZ007>009-015-016-023>026. AR...LAKE WIND ADVISORY FROM NOON TODAY TO 6 AM CST SUNDAY FOR ARZ074- 075. && $$ 08 ms AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ALBUQUERQUE NM 1220 PM MST SAT DEC 22 2007 .UPDATE... CANCELLED ALL WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES FOR THIS PM. ADJUSTED POPS...SKY COVER AND WINDS AS WELL. 40 && .PREV UPDATE...906 AM MST SAT DEC 22 2007 REMOVED THE HIGH WIND WARNING HEADLINE FROM THE NORTHEAST HIGHLANDS AND LOWERED ALL WINDS SPEEDS A NOTCH ACROSS NE NEW MEXICO. 40 && .PREV DISCUSSION...259 AM MST SAT DEC 22 2007 LATEST WATER VAPOR LOOP EARLY THIS MORNING SHOWS AN IMPRESSIVE UPPER LOW PRESSURE SYSTEM OVER THE NE PLAINS WITH A DISTINCT COMMA HEAD AND DRY SLOT FEATURE. RADAR TRENDS SHOW SNOW IS HOLDING STEADY OVER THE NORTHERN MTNS WITH CLEARING FARTHER TO THE WEST AND SOUTH...AND HEAVY SNOW ALONG THE INTERSTATE 40 CORRIDOR FROM SANTA ROSA EAST TO KTCC. WINDS ARE ALSO HOWELING OUT OF THE NORTH AT 30 TO 40 MPH CREATING VERY HAZARDOUS TRAVEL CONDITIONS IN MUCH OF THE NE PART OF THE CWA NORTH OF A FORT SUMNER TO CLOVIS LINE. WILL INCLUDE ADV LEVEL WINDS WITH THE WINTER HAZARD PRODUCTS. IR SAT SHOWS CLEARING OVER THE WESTERN HALF OF THE STATE WITH THE BACK EDGE OF THE COMMA HEAD NEARLY STATIONARY FROM CUBA SE TO KSAF. WILL CANCEL WARNINGS AND ADVISORIES THAT WERE TO EXPIRE AT 600 AM. WARNINGS WILL CONTINUE IN THE EAST WITH ANOTHER 1 TO 3 INCHES ESPECIALLY ALONG INTERSTATE 40 NEAR KTCC. ADVISORY TO THE SOUTH WILL ALSO STAY INTACT MAINLY FOR THE BLOWING SNOW HAZARD APPROACHING FROM THE NORTH. EXPECT CLEARING IN THE EAST AFTER 18Z AS INDICATED BY RUC13 SO DAY SHIFT MAY CONSIDER DROPPING ADVISORY IN THE SE AT THAT TIME. THINK WARNINGS WILL CONTINUE UNTIL 600 PM IN THE NE DUE TO EXTREMELY HAZARDOUS TRAVEL CONDITIONS. VERY COLD NIGHT EXPECTED ACROSS THE CWA...ESPECIALLY IN AREAS WITH SNOWPACK. SUNDAY WILL BE VERY NICE EARLY IN THE DAY WITH INCREASING CLOUDS OVER THE NORTH. NEXT SYSTEM WILL MOVE QUICKLY SE ACROSS THE SANGRES AND NE PLAINS SUNDAY NIGHT WITH ADVISORY LEVEL SNOWS POSSIBLE OVER THE SANGRES SIMPLY DUE TO VERY HIGH SNOW RATIOS. COLD WEATHER CONTINUES MONDAY ACROSS THE REGION DESPITE MOSTLY SUNNY SKIES. 00Z MODELS ARE BEGINNING TO CHANGE THEIR TUNE ON WEATHER PATTERN FOR CHRISTMAS INTO THE NEW YEAR WITH SYSTEMS PASSING FARTHER TO THE NORTH THAN PREVIOUS RUNS. THIS STILL MEANS POSSIBLE SIGNIFICANT WINTER STORMS FOR THE NORTHERN MOUNTAINS AND NE PLAINS HOWEVER THE SOUTH AND WEST MAY ESCAPE WITH GLANCING BLOWS. TWEAKED EXTENDED GRIDS TO ADJUST POPS SLIGHTLY FARTHER NE HOWEVER WILL WAIT FOR A MORE CONSISTENT TREND TO APPEAR. GUYER && .AVIATION... OCCASIONAL IFR CONDITIONS IN SNOW...BLOWING SNOW AND FREEZING FOG TO PERSIST FROM KSAF NORTHEAST AND EASTWARD TO THE TEXAS AND COLORADO BORDER THROUGH MIDDAY. LOCAL MOUNTAIN OBSCURATION ALONG AND WEST OF THE RIO GRANDE VALLEY EXPECTED THROUGH MIDDAY ALSO. NORTHWEST SURFACE WIND TO INCREASE AT KFMN...WITH NORTH TO NORTHWEST WINDS GUSTING TO AROUND 35 OR 40 KTS ALONG AND EAST OF CENTRAL MOUNTAIN CHAIN. WINDS SHOULD TAPER OFF LATE AFTERNOON. NEXT AVIATION DISCUSSION SCHEDULED FOR 22Z. && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 35 14 38 16 / 0 0 5 5 GALLUP.......................... 35 6 40 6 / 0 0 0 0 GRANTS.......................... 35 7 41 9 / 5 0 0 0 GLENWOOD........................ 44 21 52 23 / 0 0 0 0 CHAMA........................... 29 -4 32 -6 / 5 0 10 20 LOS ALAMOS...................... 34 8 37 5 / 10 0 5 5 RED RIVER....................... 20 2 31 5 / 20 0 10 40 TAOS............................ 33 4 38 6 / 20 0 5 20 SANTA FE........................ 32 11 36 8 / 20 0 5 5 SANTA FE AIRPORT................ 36 12 39 16 / 20 0 5 5 ESPANOLA........................ 40 10 42 17 / 20 0 5 5 ALBUQUERQUE HEIGHTS............. 42 20 43 24 / 10 0 0 0 ALBUQUERQUE VALLEY.............. 44 16 45 20 / 10 0 0 0 ALBUQUERQUE FOOTHILLS........... 42 16 41 20 / 20 0 0 0 ALBUQUERQUE WEST MESA........... 43 18 44 23 / 10 0 0 0 SOCORRO......................... 45 19 48 24 / 5 0 0 0 SANDIA PARK/CEDAR CREST......... 37 12 38 14 / 20 0 5 0 MORIARTY/ESTANCIA............... 37 17 40 19 / 30 0 0 0 CARRIZOZO....................... 39 20 42 21 / 20 0 0 0 RUIDOSO......................... 32 17 40 17 / 20 0 0 0 RATON........................... 32 8 40 11 / 30 0 5 20 LAS VEGAS....................... 31 14 38 13 / 50 0 5 20 ROY............................. 35 16 37 15 / 60 0 5 20 CLAYTON......................... 33 14 40 18 / 60 0 0 20 SANTA ROSA...................... 42 16 43 20 / 60 0 0 5 TUCUMCARI....................... 38 13 42 18 / 60 0 0 20 FORT SUMNER..................... 43 19 50 20 / 60 0 0 0 CLOVIS.......................... 37 19 48 21 / 70 0 0 0 PORTALES........................ 39 19 48 20 / 70 0 0 0 ROSWELL......................... 48 22 52 25 / 30 0 0 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 6 PM MST THIS AFTERNOON FOR THE FOLLOWING ZONES...NMZ002>007-010>013. WINTER WEATHER ADVISORY UNTIL 6 PM MST THIS AFTERNOON FOR THE FOLLOWING ZONES...NMZ016>021-026. && $$ GUYER/99 nm AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE AMARILLO TX 1129 AM CST SAT DEC 22 2007 .AVIATION... IT APPEARS THAT THE SNOW HAS PUSHED THROUGH ALL THE TAF SITES... HAVING JUST ENDED AT KAMA. COULD STILL SEE A FEW BANDS OF SNOW MOVE ACROSS THE KAMA TAF THROUGH 20Z AND HAVE PLACED THIS IN A TEMPO GROUP. BIGGEST PROBLEM WILL BE THE STRONG NORTHERLY WINDS PERSISTING THROUGH THE AFTERNOON. HAVE DECIDED TO KEEP 4SM BLSN AT KAMA TAF SITE PREVAILING THROUGH 22Z AS STRONG WINDS LOFT SNOW THAT HAS FALLEN. MORE THAN LIKELY...VISIBILITIES WILL REMAIN AT OR ABOVE 6SM THROUGH THE AFTERNOON. SKIES WILL CONTINUE TO CLEAR FROM NORTHWEST TO SOUTHEAST THROUGH THIS AFTENROON WITH VFR CONDITIONS BY 22Z. WINDS WILL SLOW DOWN TO LIGHT AND VARIABLE AFTER SUNSET AS WELL. && .PREV DISCUSSION... /ISSUED 552 AM CST SAT DEC 22 2007/ AVIATION... WINTRY WEATHER WILL MAINTAIN IFR/LIFR CONDITIONS DURING THE MORNING HOURS AS THE TRAILING EDGE OF THE EXITING LOW PRESSURE SYSTEM PRODUCING SNOW AND BLOWING SNOW. THOUGH THE SNOW SHOULD END BY MIDDAY OVER KAMA...KDHT AND KGUY...STRONG WINDS WILL CONTINUE INTO THE AFTERNOON. VFR CONDITIONS SHOULD RETURN BY LATE AFTERNOON. NUNEZ PREV DISCUSSION... /ISSUED 442 AM CST SAT DEC 22 2007/ DISCUSSION... MAIN FORECAST CONCERN DEALS WITH THE SHORT TERM DETAILS WHICH INCLUDES PRECIP TIMING AND WINDS. CURRENT WV IMAGERY WITH RUC UPPER AIR ANALYSIS OVERLAY SHOW A VIGOROUS UPPER TROUGH OVER NEW MEXICO. A 120 KT JET WAS PUNCHING INTO THE BASE OF THE TROUGH...WHICH WILL ACT TO ACCELERATE IT NORTHEAST TO THE GREAT LAKES BY SUN. CURRENT RADAR SHOWS AN AREA OF MIXED PRECIPITATION SPREADING INTO PORTIONS OF THE PANHANDLES. WITH SFC TEMPS HOVERING NEAR OR BELOW FREEZING...EXPECT A CHANGE OVER TO ALL SNOW SOON. FOR TODAY...THE UPPER TROUGH WILL QUICKLY MOVE ACROSS THE TEXAS PANHANDLE. STRONG UPPER DYNAMICS WILL REMAIN ACROSS THE PANHANDLES THIS MORNING...SO EXPECT THE HEAVIEST SNOWFALL TO OCCUR THEN. ONE CAVEAT TO THIS IS THAT SFC WINDS DO NOT HAVE MUCH OF AN UPSLOPE COMPONENT WHICH WOULD LIMIT THE AMOUNT OF LLVL MOISTURE. IRREGARDLESS...FCST SOUNDINGS INDICATE FAIRLY SATURATED PROFILES WITH TEMPS BELOW FREEZING THROUGHOUT THE COLUMN SO PRECIP THIS MORNING SHOULD BE ALL SNOW. SINCE THIS IS A PROGRESSIVE SYSTEM... SNOW WILL END FROM WEST TO EAST AND ADJUSTED POPS TO END THE TIMING OF THE SNOW SOONER ACROSS THE WESTERN PORTIONS OF THE CWA. STILL EXPECT THE GREATEST ACCUMULATIONS IN THE OKLAHOMA PANHANDLE WHERE CLOSE TO 4 INCHES IS POSSIBLE. GIVEN THIS...CONTINUED THE SNOW AND BLOWING SNOW ADVISORY WHICH EXPIRES THIS EVENING. IN ADDITION TO PRECIP...STRONG NORTHERLY WINDS WILL CONTINUE TODAY BEFORE DIMINISHING TONIGHT. CURRENT OBS ALREADY SHOW SPEEDS IN EXCESS OF 30 KTS IN THE FAR NORTHWEST PORTION OF THE PANHANDLES AND THE TUCUMCARI PROFILER SHOWS WINDS OF 35 KTS AROUND 900 MB. WITH STRONG CAA AND PRESSURE RISES ON THE ORDER OF 5 MB...SEE NO REASON WHY THE CWA WILL NOT SEE ADVISORY CRITERIA WINDS SO HOISTED A WIND ADVISORY FOR THE ENTIRE CWA THROUGH 6 PM THIS EVENING. SKIES WILL RAPIDLY CLEAR TONIGHT AND WITH DIMINISHING WINDS AND AN ANTICIPATED FRESH SNOW PACK...WENT SLIGHTLY UNDER MOS GUIDANCE FOR TEMPS TONIGHT...WITH LOWS MAINLY IN THE TEENS. MODELS CONTINUE TO ADVERTISE A PROGRESSIVE WEATHER PATTERN AS SEVERAL UPPER TROUGHS MOVE ACROSS THE PLAINS. THE FIRST WILL DROP SOUTHEAST OUT OF THE INTER MOUNTAIN WEST AND MOVE ACROSS THE CWA SUN NIGHT AND MON. DID INCREASE POPS A BIT BUT STILL KEPT THEM SILENT AS ASCENT INCREASES AHEAD OF THE APPROACHING UPPER TROUGH ALTHOUGH MID AND UPPER MOISTURE REMAINS LIMITED. ANOTHER UPPER TROUGH IS PROGGED TO DROP SOUTHEAST ON CHRISTMAS DAY AND CROSS THE PANHANDLES THAT NIGHT. THIS SYSTEM LOOKS TO TAP INTO MORE MOISTURE SO MAINTAINED SLIGHT CHANCE POPS. DID PUSH BACK THE TIMING OF PRECIP TO THAT EVENING AS SYNOPTIC SCALE LIFT AND MOISTURE LOOKS TO BE MAXIMIZED THEN. FINAL TROUGH WILL ALSO DROP SOUTHEAST AND MOVE ACROSS THE CENTRAL PLAINS THU. THE OPERATIONAL GFS IS MORE PROGRESSIVE THAN ENSEMBLES SO KEPT THE DRY FCST INTACT. AS FOR TEMPS...GENERALLY FOLLOWED MEXMOS GUIDANCE WITH TEMPS GENERALLY RUNNING BELOW AVERAGE. CLK AMA WATCHES/WARNINGS/ADVISORIES... TX...SNOW AND BLOWING SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH... DALLAM...DEAF SMITH...DONLEY...GRAY...HANSFORD...HARTLEY... HEMPHILL...HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE... OLDHAM...POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...COLLINGSWORTH...DALLAM...DEAF SMITH...DONLEY...GRAY...HANSFORD...HARTLEY...HEMPHILL... HUTCHINSON...LIPSCOMB...MOORE...OCHILTREE...OLDHAM... POTTER...RANDALL...ROBERTS...SHERMAN...WHEELER. OK...SNOW AND BLOWING SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: BEAVER...CIMARRON...TEXAS. $$ tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 1107 AM CST SAT DEC 22 2007 .UPDATE... AREA OBSERVATIONS ACROSS THE GUADALUPE AND DAVIS MOUNTAINS SHOW HIGH WINDS HAVE COME TO AN END. HOWEVER...WINDS OVER THE HIGHER ELEVATIONS OF THE DAVIS MOUNTAINS CONTINUE TO REMAIN GUSTY. WE HAVE ALLOWED THE HIGH WIND WARNING TO EXPIRE...AND HAVE OPTED TO ISSUE A WIND ADVISORY FOR THE THE DAVIS MOUNTAINS THROUGH 00Z. NO CHANGES HAVE BEEN MADE TO THE WIND ADVISORY ACROSS THE EASTERN PERMIAN BASIN AND WESTERN LOW ROLLING PLAINS. OTHERWISE...MINOR CHANGES WERE MADE TO THE WIND AND DEW POINT GRIDS. && .PREV DISCUSSION... /ISSUED 627 AM CST SAT DEC 22 2007/ UPDATE... WENT AHEAD AND ISSUED A WIND ADVISORY FOR THE EASTERN PERMIAN BASIN. LATEST RUC SHOWING WINDS 5 TO 10 KTS HIGHER THAN EITHER THE GFS AND NAM ARE SHOWING. SURFACE OBSERVATIONS TO THE NORTH ARE SHOWING MINIMAL ADVISORY CONDITIONS A THE MOMENT...HOWEVER STRONG DOWNWARD FORCING IN THE WAKE OF THE UPPER LOW AND CLEAR SKIES WILL ALLOW FOR MAXIMUM POTENTIAL OF ELEVATED STRONG WINDS TO MIX TO THE SURFACE. THIS IS A TOUGH CALL WITH THE ADVISORY POSSIBLY NEEDING TO BE EXPANDED SOUTH AND WEST...BUT WANTED TO START OUT HIGHLIGHTING THE AREA WITH THE HIGHEST POTENTIAL FIRST AND WILL LET THE NEXT SHIFT MAKE THE DECISION TO FINE TUNE FURTHER. HENNIG PREV DISCUSSION... /ISSUED 518 AM CST SAT DEC 22 2007/ AVIATION... WINDS WILL BE THE BIGGEST PROBLEM TODAY ACROSS AREA TAFS... ALTHOUGH A FEW LOWER CLOUDS COULD ALSO MATERIALIZE ACROSS EASTERN TAF SITES LATER THIS MORNING. EXPECT WINDS TO SWITCH AROUND TO THE NORTH NEAR OR SHORTLY AFTER SUNRISE AS THE COLD FRONT CONTINUES TO PUSH SOUTH THROUGH THE AREA. WINDS BEHIND THE FRONT HAVE BEEN 20KT WITH GUSTS TO GREATER THAN 30KT AT TIMES. THINK WINDS ACROSS THE AREA COULD FOLLOW THIS TREND THROUGH THE AFTERNOON WHEN WINDS SHOULD BEGIN DYING DOWN. EXPECT NEAR CALM WINDS OVERNIGHT. LOW CLOUDS WILL HAVE A CHANCE TO FORM ALONG AND NEAR THE FRONT LATER THIS MORNING. WILL LIKELY ONLY BRIEFLY TOUCH MVFR CONDITIONS BEFORE QUICKLY GOING BACK TO VFR CONDITIONS AGAIN. THEN VFR CONDITIONS WILL BE EXPECTED THIS AFTERNOON AND INTO THE OVERNIGHT HOURS TONIGHT. /13/ PREV DISCUSSION... /ISSUED 329 AM CST SAT DEC 22 2007/ DISCUSSION... COLD FRONT HAS MOVED THROUGH THE TEXAS PANHANDLE AND WILL BE INTO THE NORTHERN PERMIAN BASIN NOT LONG AFTER SUNRISE. WINDS WILL SHIFT AROUND TO THE NORTH BEHIND THE FRONT AND BECOME BREEZY TO WINDY AS STRONG CAA DOMINATES IN THE WAKE OF THE DEPARTING UPPER LEVEL LOW. WINDS ARE CURRENTLY GUSTING IN EXCESS OF 40 KTS BEHIND THE FRONT AND A WIND ADVISORY MAY NOT BE OUT OF THE QUESTION FOR TODAY BUT A WEAKER PRESSURE GRADIENT IN THE PB SHOULD PRECLUDE ISSUANCE. WENT AHEAD AND LEFT POPS IN THE EXTREME NORTHERN COUNTIES...BUT GIVEN THE PRONOUNCED DRY SLOT OVER THE CWA ON WV IMAGERY...RAIN OR SNOW CHANCES SEEM PRETTY DISMAL. ELSEWHERE IN THE SHORT TERM STRONG WINDS IN THE HIGHER ELEVATIONS ARE BEGINNING TO SUBSIDE AND THE HIGH WIND WARNING WILL MOST LIKELY BE ALLOWED TO EXPIRE...THOUGH WINDS IN THE DAVIS MOUNTAINS ARE STILL PRETTY HIGH AND WILL NEED TO BE CLOSELY WATCHED. THE REMAINDER OF THE FORECAST PACKAGE WILL BE A SERIES OF REPEAT PERFORMANCES AS ZONAL FLOW SENDS SEVERAL UPPER LEVEL LOWS ACROSS THE CENTRAL PLAINS WHICH IN TURN WILL GIVE US MULTIPLE COLD FRONTAL PASSAGES. THIS FORECAST PACKAGE STAYED CLOSE TO THE GFS. THE 21/12Z ECMWF SEEMED TOO SLOW AND DEEP WITH THE UPPER PATTERN...ESPECIALLY WITH REGARDS THE LOW SEEN APPROACHING AROUND CHRISTMAS. WE SHOULD SEE SEVERAL SHOTS OF COOL AIR BUT WE ARE NOT GOING TO BE ABLE TO TAP INTO ANY ARCTIC AIR SO THE TEMPS WILL BE QUICK TO REBOUND. CHRISTMAS PROMISES TO BE A NICE DAY WITH DRY WEATHER AND NEAR TO ABOVE NORMAL TEMPERATURES. HENNIG && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...WIND ADVISORY FROM 10 AM THIS MORNING TO 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES...BORDEN...DAVIS/APACHE MOUNTAINS AREA...DAWSON...GLASSCOCK...HOWARD...MARTIN...MIDLAND... MITCHELL...REAGAN...SCURRY...UPTON. && $$ 76/99 tx