Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/02/13


AREA FORECAST DISCUSSION
NWS PHOENIX AZ
856 AM MST MON DEC 31 2012 .SYNOPSIS... SNOW SHOWERS TO THE EAST OF PHOENIX WILL TAPER OFF THROUGH THE DAY...WITH ONLY MINOR ACCUMULATIONS EXPECTED IN THE HIGHEST ELEVATIONS. VERY COLD AIR WILL SETTLE OVER THE AREA TONIGHT WITH FREEZE WARNINGS IN PLACE ACROSS THE LOWER ARIZONA DESERTS. A GRADUAL CLIMB BACK TOWARD NORMAL TEMPERATURES WILL BEGIN ON TUESDAY LASTING THROUGH THE WEEKEND. && .DISCUSSION... MID MORNING SATELLITE IMAGERY REVEALS AN UPPER LOW OVER CENTRAL ARIZONA...WITH A TROUGH AXIS STRETCHING BACK THROUGH EASTERN ARIZONA INTO SONORA. REGIONAL RADAR IMAGERY INDICATES THAT THE VAST MAJORITY OF THE PRECIP HAS EXITED THE FORECAST AREA AND IS NOW CONCENTRATED IN NEW MEXICO. REPORTS IN AND AROUND GLOBE INDICATE THAT ROUGHLY AN INCH OF SNOW HAS FALLEN SINCE LAST NIGHT AROUND 4000FT...WITH HIGHER AMOUNTS LIKELY ABOVE THAT. MEANWHILE ACROSS THE LOWER DESERTS...PRECIP AMOUNTS APPEAR TO BE CONFINED TO AREAS EAST OF INTERSTATE 17 FOR THE MOST PART /THERE ARE A FEW REPORTS OF A HUNDREDTH OR TWO IN THE WEST VALLEY/. MOST NUMBERS IN THE EAST VALLEY ARE BETWEEN A TENTH AND A QUARTER OF AN INCH. PRECIP HAS LONG SINCE ENDED THOUGH WITH SUNNY SKIES AND COOL TEMPERATURES PREVAILING. IN THE VERY SHORT TERM...THE 12Z NAM AND 14Z RAP MODELS INDICATE THAT ALL THE STRONGEST UVV HAS EXITED THE AREA...WITH ONLY WEAK ASCENT NOTED IN THE 850-500MB LAYER. VERTICAL MOTION THROUGH THE DENDRITIC GROWTH REGION IS VERY WEAK AND WILL ONLY CONTINUE TO DIMINISH AS THE REST OF THE MORNING GOES ON. WHILE THE UPPER LEVEL COLD POOL WILL REMAIN IN PLACE FOR THE REST OF THE MORNING...A LOOP OF WV IMAGERY INDICATES IT SHOULD BEGIN EXITING THE AREA SHORTLY. HI RES WRF MODELS ONLY SHOW A FEW INSTABILITY SHOWERS DEVELOPING NORTH AND EAST OF PHOENIX WITH THE REST OF THE AREA REMAINING DRY. I WILL DISCONTINUE THE WINTER WEATHER ADVISORY A FEW HOURS EARLY AS THE OVERALL TREND WILL BE ONE OF IMPROVING CONDITIONS. WILL ONLY MAKE MINOR ADJUSTMENTS TO THE TEMPS/CLOUD COVER FORECAST FOR TODAY BASED ON OBSERVATIONAL TRENDS THROUGH MID MORNING. CERTAINLY WILL BE A CHILLY END TO THE YEAR WITH TEMPS ABOUT 10-15 DEGREES BELOW NORMAL. && .PREVIOUS DISCUSSION... WITH COLDER AIRMASS ALOFT...DAYTIME TEMPS TODAY EXPECTED ON THE ORDER OF 8 TO 12 DEGREES BELOW LATE DECEMBER NORMALS. OVERNIGHT IN THE WAKE OF TROUGH MOSTLY CALM WINDS...STILL COLD AIRMASS ALOFT AND CLEARING SKIES WILL SUPPORT FREEZING TEMPERATURES FOR THE DESERTS ACROSS LA PAZ...YUMA...MARICOPA AND PINAL COUNTIES. AS SUCH...THE PREVIOUSLY ISSUED FREEZE WATCH HAS BEEN UPGRADED TO A FREEZE WARNING FOR TUESDAY MORNING. EARLIER FORECAST MODEL RUNS SHOWED A SECONDARY DRY WEATHER SYSTEM SKIRTING THROUGH THE REGION FROM THE GREAT BASIN STATES TUESDAY AFTN. LATEST RUNS NOW DROP THIS SYSTEM WELL TO OUR SOUTH MOVING IT ACROSS NORTHERN MEXICO FOR WEDNESDAY. OUTSIDE OF INCREASED NORTHERLY BREEZES ALONG THE COLORADO RIVER VALLEY AND ANOTHER SHOT OF COOLER AIR...THIS SYSTEM WILL HAVE LITTLE IMPACT TO THE FORECAST AREA. WEDNESDAY MORNING COULD HAVE ANOTHER COOL START AS SKIES ONCE AGAIN WILL CLEAR ACROSS THE REGION. HOWEVER...EASTERLY BREEZES OVERNIGHT IN RESPONSE TO THE TROUGHING DRAPING ACROSS THE DIVIDE AND INTO EASTERN ARIZONA MAY AIDE IN KEEPING THE LOWER DESERTS MIXED OVERNIGHT. STILL CONFIDENT THAT TUESDAY AM WILL BE THE COLDEST...BUT COULD SEE COOL ENOUGH TEMPS TO POSSIBLY WARRANT A SPECIAL WEATHER STATEMENT FOR NEAR FREEZING TEMPERATURES WEDNESDAY AM...STAY TUNED. FOR THE EXTENDED PERIOD...LONGWAVE TROUGHING ACROSS THE SOUTHERN U.S. WILL LINGER INTO EAST CENTRAL ARIZONA WHILE UPPER LEVEL RIDGING BEGINS TO AMPLIFY OVER THE WEST COAST. TEMPERATURES WILL SEE A SLOW WARMING TREND THROUGH MIDWEEK AS HEIGHTS BEGIN TO ELEVATE ALOFT AND CONDITIONS WILL REMAIN DRY. FORECAST SPREAD GREATLY INCREASES BEYOND SATURDAY...AS THE EURO/GEM SOLNS BEGIN TO FAVOR THE BREAKDOWN OF THE RIDGE AND A CUTOFF FEATURE DROPPING OUT OF THE PAC NW DOWN THE WEST COAST FOR EARLY NEXT WEEK. THE GFS LAGS BEHIND WITH A SLOWER MOVING CUTOFF FEATURE CIRCULATING NEAR 130W 30N FOR NEXT MONDAY. BLENDED IN SOME OF THE CLIMO POP GRID INFLU FOR SATURDAY AND BEYOND...OTHERWISE HELD OFF ON ADDITIONAL GRID CHANGES. && .AVIATION... SOUTH CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL... THROUGH 15Z MON...BKN 3-5 THSD AGL...ISOLD RAIN SHWR. LIGHT WIND. FROM 15Z MON TO 20Z MON...SCT 5 THSD AGL...SCT-BKN 100 AGL. LIGHT WIND. FRM 20Z MON TO 03Z TUE...SCT 6 THSD AGL. LIGHT WIND. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... THROUGH 03Z TUE...GENERALLY CLEAR SKIES. NORTH WIND 5 TO 10 KNOTS. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... WEDNESDAY THROUGH SUNDAY... A DRY COLD AIRMASS WILL CONTINUE TO COVER THE REGION THROUGH THURSDAY. NORTHEAST BREEZES...SOMETIMES GUSTY...IN THE 10 TO 20 MPH RANGE CAN BE EXPECTED WEDNESDAY. MINIMUM RH VALUES IN THE 15 TO 20 PERCENT RANGE WILL CONTINUE. THURSDAY THROUGH SUNDAY...DRY CONDITIONS WITH WARMER TEMPERATURES WILL DEVELOP. LIGHT WIND. MINIMUM RH VALUES WILL CONTINUE IN THE 15 TO 20 PERCENT RANGE. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...FREEZE WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY MORNING AZZ021>023-026>028. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...LEINS/NOLTE AVIATION...VASQUEZ FIRE WEATHER...VASQUEZ
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
352 AM MST MON DEC 31 2012 .SYNOPSIS... LIGHT MOUNTAIN SNOW SHOWERS WILL CONTINUE FOR THE HIGHER TERRAIN EAST OF PHOENIX THROUGH THE MORNING HOURS WITH LIGHTER MORE ISOLATED RAIN SHOWERS LINGERING ACROSS CENTRAL ARIZONA. LIGHT INSTABILITY SHOWERS ARE POSSIBLE THIS AFTERNOON ACROSS THE CENTRAL ARIZONA DESERTS WITH DAYTIME TEMPERATURES EXPECTED WELL BELOW NORMAL. COOL DAYTIME TEMPERATURES COMBINED WITH COLD AIR ALOFT WILL SUPPORT FREEZING TEMPERATURES TUESDAY MORNING EAST OF THE COLORADO RIVER INTO CENTRAL ARIZONA. TEMPERATURES WILL BEGIN A SLOW WARM UP TUESDAY...LASTING THROUGH THE END OF THE WEEK WITH DRY CONDITIONS EXPECTED AS WELL. && .DISCUSSION... SCATTERED LIGHT SHOWER ACTIVITY CONTINUES ACROSS PHOENIX AND EAST TOWARDS THE HIGHER TERRAIN AS THE UPPER TROUGH AND COLD FRONT CONTINUE TO MOVE THROUGH ARIZONA THIS MORNING. OUT WEST ACROSS SE CA THE SHOWER ACTIVITY HAS ENDED WITH ONLY ISOLATED PATCHES OF STRATOCU LINGERING. HRRR AND LOCAL WRF MODELS STILL HANDLING PRECIP PLACEMENT/TIMING THE BEST THIS AM...WITH WIDESPREAD SHOWER ACTIVITY CURRENTLY EXPANDING ACROSS SOUTHERN ARIZONA FROM CENTRAL PINAL COUNTY...THROUGH TUCSON...NOGALES AND POINTS EAST. SAMPLING 3AM TEMPS/DEWPOINTS AROUND THE AREA...SNOW LEVELS ESTIMATED BETWEEN 3500 AND 4000 FEET. ADDITIONAL POCKETS OF VORT ENERGY WILL MOVE THROUGH THE REGION AROUND THE TROUGH BASE...CONTINUING LIGHT PRECIP ACTIVITY ESPECIALLY FOR THE UPSLOPE AREAS EAST OF PHOENIX THROUGH MIDDAY. WILL CONTINUE THE WINTER WEATHER ADVISORY FOR AREAS ABOVE 4000FT IN ZONE 24...SOUTHERN GILA COUNTY...THROUGH THE MORNING AS ADDITIONAL LIGHT SNOW ACCUMULATIONS ARE POSSIBLE. LAST DAY OF 2012 INTO NEW YEARS EVE...EXPECT A GRADUAL CLEARING OF SKIES FROM THE WEST WITH SLIGHT CHANCES FOR AFTN INSTABILITY SHOWERS TO FILL IN ACROSS PORTIONS OF THE CENTRAL AZ DESERTS. WITH COLDER AIRMASS ALOFT...DAYTIME TEMPS TODAY EXPECTED ON THE ORDER OF 8 TO 12 DEGREES BELOW LATE DECEMBER NORMALS. OVERNIGHT IN THE WAKE OF TROUGH MOSTLY CALM WINDS...STILL COLD AIRMASS ALOFT AND CLEARING SKIES WILL SUPPORT FREEZING TEMPERATURES FOR THE DESERTS ACROSS LA PAZ...YUMA...MARICOPA AND PINAL COUNTIES. AS SUCH...THE PREVIOUSLY ISSUED FREEZE WATCH HAS BEEN UPGRADED TO A FREEZE WARNING FOR TUESDAY MORNING. EARLIER FORECAST MODEL RUNS SHOWED A SECONDARY DRY WEATHER SYSTEM SKIRTING THROUGH THE REGION FROM THE GREAT BASIN STATES TUESDAY AFTN. LATEST RUNS NOW DROP THIS SYSTEM WELL TO OUR SOUTH MOVING IT ACROSS NORTHERN MEXICO FOR WEDNESDAY. OUTSIDE OF INCREASED NORTHERLY BREEZES ALONG THE COLORADO RIVER VALLEY AND ANOTHER SHOT OF COOLER AIR..THIS SYSTEM WILL HAVE LITTLE IMPACT TO THE FORECAST AREA. WEDNESDAY MORNING COULD HAVE ANOTHER COOL START AS SKIES ONCE AGAIN WILL CLEAR ACROSS THE REGION. HOWEVER...EASTERLY BREEZES OVERNIGHT IN RESPONSE TO THE TROUGHING DRAPING ACROSS THE DIVIDE AND INTO EASTERN ARIZONA MAY AIDE IN KEEPING THE LOWER DESERTS MIXED OVERNIGHT. STILL CONFIDENT THAT TUESDAY AM WILL BE THE COLDEST...BUT COULD SEE COOL ENOUGH TEMPS TO POSSIBLY WARRANT A SPECIAL WEATHER STATEMENT FOR NEAR FREEZING TEMPERATURES WEDNESDAY AM...STAY TUNED. FOR THE EXTENDED PERIOD...LONGWAVE TROUGHING ACROSS THE SOUTHERN U.S. WILL LINGER INTO EAST CENTRAL ARIZONA WHILE UPPER LEVEL RIDGING BEGINS TO AMPLIFY OVER THE WEST COAST. TEMPERATURES WILL SEE A SLOW WARMING TREND THROUGH MIDWEEK AS HEIGHTS BEGIN TO ELEVATE ALOFT AND CONDITIONS WILL REMAIN DRY. FORECAST SPREAD GREATLY INCREASES BEYOND SATURDAY...AS THE EURO/GEM SOLNS BEGIN TO FAVOR THE BREAKDOWN OF THE RIDGE AND A CUTOFF FEATURE DROPPING OUT OF THE PAC NW DOWN THE WEST COAST FOR EARLY NEXT WEEK. THE GFS LAGS BEHIND WITH A SLOWER MOVING CUTOFF FEATURE CIRCULATING NEAR 130W 30N FOR NEXT MONDAY. BLENDED IN SOME OF THE CLIMO POP GRID INFLU FOR SATURDAY AND BEYOND...OTHERWISE HELD OFF ON ADDITIONAL GRID CHANGES. && .AVIATION... SOUTH CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL... THROUGH 15Z MON...BKN 3-5 THSD AGL...ISOLD RAIN SHWR. LIGHT WIND. FROM 15Z MON TO 20Z MON...SCT 5 THSD AGL...SCT-BKN 100 AGL. LIGHT WIND. FRM 20Z MON TO 03Z TUE...SCT 6 THSD AGL. LIGHT WIND. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... THROUGH 03Z TUE...GENERALLY CLEAR SKIES. NORTH WIND 5 TO 10 KNOTS. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... WEDNESDAY THROUGH SUNDAY... A DRY COLD AIRMASS WILL CONTINUE TO COVER THE REGION THROUGH THURSDAY. NORTHEAST BREEZES...SOMETIMES GUSTY...IN THE 10 TO 20 MPH RANGE CAN BE EXPECTED WEDNESDAY. MINIMUM RH VALUES IN THE 15 TO 20 PERCENT RANGE WILL CONTINUE. THURSDAY THROUGH SUNDAY...DRY CONDITIONS WITH WARMER TEMPERATURES WILL DEVELOP. LIGHT WIND. MINIMUM RH VALUES WILL CONTINUE IN THE 15 TO 20 PERCENT RANGE. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...FREEZE WATCH FROM LATE MONDAY NIGHT THROUGH TUESDAY MORNING AZZ021>023-026>028. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON MST MONDAY ABOVE 4000 FEET FOR AZZ024. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...NOLTE AVIATION...VASQUEZ FIRE WEATHER...VASQUEZ
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
300 PM MST MON DEC 31 2012 .SHORT TERM...(THIS EVENING THROUGH TUESDAY NIGHT) ISSUED AT 300 PM MST MON DEC 31 2012 IMPROVING CONDITIONS AS THE ACTIVE SHORT WAVE MOVES DOWNSTREAM...EXCEPT FOR SOME ENHANCED CONVECTIVE SNOW SHOWERS OVER THE SAN JUANS. SOME OF THIS ACTIVITY STILL IMPACTING PAGOSA SPRINGS...AND THE HIGHER RESOLUTION RAP MODEL KEEPS SNOW ONGOING INTO THE EVENING HOURS BUT ENDING BY MID EVENING. REFINED THE WINTER WEATHER ADVISORY FOR THIS AREA AS CONFIDENCE IS HIGH THAT SNOW WILL HAVE ENDED BY LATE EVENING. WITH PARTIAL CLEARING OVERNIGHT...TEMPERATURES WILL PLUNGE AFTER SUNSET AND THEN LEVEL OUT AROUND MIDNIGHT. UPSTREAM DISTURBANCE OVER MONTANA AND NORTH DAKOTA KEEPS A TROUGH CARVED OUT OVER WESTERN COLORADO ON NEW YEARS DAY. MOISTURE SOURCE FOR THIS SHORT WAVE IS CONTINENTAL AND THEREFORE PRECIPITABLE WATER IS LOW...BUT DOES KEEP THE AIR MASS UNSETTLED DURING THE LATE MORNING AND EARLY AFTERNOON HOURS. EXPECT SHALLOW CONVECTIVE SNOW SHOWERS OR FLURRIES TO FORM ACROSS THE HIGH COUNTRY. AREAL COVERAGE WILL NOT BE WIDESPREAD AND FAVOR NORTH FACING SLOPES. ESSENTIALLY THIS SHORT WAVE KEEPS THE COLD AIR MASS LOCKED IN. 2013 STARTS THE WAY THAT 2012 ENDED...COLD WITH LITTLE CHANGE. THE FOLLOWING UPSTREAM WAVE BRUSHES THE PARK/GORE RANGE LATE ON TUESDAY NIGHT. LIMITED MOISTURE ONCE AGAIN BUT SOME OROGRAPHIC FLURRIES ARE EXPECTED...OTHERWISE MOSTLY CLEAR WITH STRONG RADIATIONAL COOLING AS SURFACE HIGH PRESSURE COVERS THE REGION. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 300 PM MST MON DEC 31 2012 IN GENERAL...LOOKS LIKE A MOSTLY DRY LAST HALF OF THE WEEK AS A BLOCKING RIDGE DEVELOPS OVER THE INTERMOUNTAIN WEST WED AND THU. AS THIS OCCURS...A SHORTWAVE IN NORTHERLY FLOW CLIPS OUR AREA WED AS IT DROPS FROM CENTRAL CANADA THROUGH THE PLAINS. LITTLE MOISTURE ASSOCIATED WITH IT OVER CO...SO WILL CONTINUE WITH JUST A SLIGHT CHANCE OF SNOW MAINLY NEAR THE CONTINENTAL DIVIDE. LATE IN THE WEEK...A PACIFIC SHORTWAVE FIGHTS THROUGH/OVER THE RIDGE CROSSING THE NORTHERN ROCKIES EARLY ON FRIDAY AND BRUSHING BY OUR AREA ON SATURDAY. AGAIN...LITTLE MOISTURE ASSOCIATED WITH IT IN THE MODELS. RIDGE REBOUNDS OVER UT/CO BY SUNDAY. ECMWF THEN BRINGS A PROGRESSIVE PACIFIC TROUGH ACROSS OUR AREA ON MONDAY...WHILE THE GFS INSTEAD CLOSES OFF A LOW ALONG THE WEST. THE MAIN CHALLENGE FOR THIS FORECAST PERIOD MAY BE THE VALLEY TEMPERATURES...WHICH WILL BE SLOW TO WARM. SNOW COVER AND TRAPPED COLD AIR WITH HIGH PRESSURE AT THE SURFACE WILL PROMOTE SURFACE INVERSIONS WED-FRI THAT WILL BE DIFFICULT TO DISLODGE. THE WEAK DISTURBANCES WED AND SAT DON/T LOOK STRONG ENOUGH TO SCOUR OUT MANY VALLEYS...AND AREAS LIKE THE GRAND VALLEY AND I-70 CORRIDOR WILL SEE AIR QUALITY SLOWLY DECLINE. HAVE UNDERCUT MOS AND CONSENSUS GUIDANCE FOR THE VALLEYS AS A RESULT. HIGHER ELEVATIONS... HOWEVER...SHOULD SEE A SLOW MODERATION IN TEMPS BY THE WEEKEND. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING) ISSUED AT 300 PM MST MON DEC 31 2012 CEILING AND VISIBILITY WILL GRADUALLY IMPROVE NEAR AND ACROSS THE MOUNTAINS THIS EVENING AS SNOW DIMINISHES IN MOST AREAS BY 06Z. THE MAIN AVIATION CONCERN WILL THEN BE THE POTENTIAL FOR FOG FORMATION IN MANY OF THE VALLEYS. DO NOT ANTICIPATE DENSE FOG WITH THE LACK OF SIGNIFICANT MELTING TO REALLY MOISTEN THE AIR NEXT TO THE GROUND ...BUT COLD TEMPERATURES AND FRESH SNOW COVER NEVERTHELESS COULD RESULT IN SOME FOG. WILL ACCOUNT FOR THIS POSSIBILITY WITH EITHER VCFG OR MVFR VISIBILITY IN BR IN ALL TAFS TONIGHT. VFR CONDITIONS EXPECTED AT ALL TAF SITES TUESDAY AFTERNOON. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL 9 PM MST THIS EVENING FOR COZ018- 019-023. UT...NONE. && $$ SHORT TERM...PF LONG TERM...JAD AVIATION...JAD
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
907 PM CST TUE JAN 1 2013 .DISCUSSION... 811 PM CST FOR EVENING UPDATE... HAVE TWEAKED GOING FORECAST FOR TONIGHT MAINLY TO LOWER MIN TEMPS 1-3 DEGREES MOST AREAS AND ESPECIALLY NORTHWEST...AND TO INCREASE SKY COVER AFTER MIDNIGHT ACROSS THE FAR NORTH. EARLY EVENING ANALYSIS PLACES SURFACE HIGH PRESSURE FROM THE SOUTHERN PLAINS INTO THE MID-MISSISSIPPI RIVER VALLEY. NORTHEAST EXTENT OF SURFACE RIDGE AXIS EXTENDS INTO NORTHERN IL...WHERE CLEAR SKIES WERE ALLOWING STRONG RADIATIONAL COOLING AS WINDS DECOUPLE IN/NEAR THE RIDGE AXIS. BASED ON THESE TRENDS HAVE LOWERED TEMPS ACROSS MUCH OF THE AREA BY UP TO SEVERAL DEGREES...CLOSER TO SOME OF THE COOLER MOS GUIDANCE FROM 12/18Z. OTHER FACTOR OF NOTE THIS EVENING IS THE AREA OF STRATUS OVER MUCH OF THE UPPER MISSISSIPPI VALLEY...WHICH HAS BEEN DRIFTING EAST DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. STOUT LOW LEVEL INVERSION ASSOCIATED WITH MODIFIED-ARCTIC AIR AND DENSE SNOW PACK ACROSS AREAS WEST/NORTHWEST OF THE CWA WAS NOTED IN 12Z RAOBS FROM UPSTREAM LOCATIONS. 21-00Z RAP FORECASTS OF 950-900 MB LAYER RH SEEM TO CAPTURE THE EXTENT OF THE STRATUS FAIRLY WELL...AND SUGGEST THAT THESE CLOUDS WILL SPREAD EAST INTO FAR NORTHERN IL AFTER MIDNIGHT AND PERHAPS EVEN SHIFT A LITTLE SOUTHEAST THROUGH EARLY WEDNESDAY MORNING. OTHER GUIDANCE HAS NOT HANDLED THE EXTENT/ADVECTION OF THE STRATUS VERY WELL. BASED ON SATELLITE TRENDS AND THE RAP FORECASTS...WHICH SEEM REASONABLE GIVEN THIS MOISTURE TRAPPED WITHIN STABLE LOW LEVELS...HAVE INCREASED CLOUD COVER OVER FAR NORTHERN IL LATE TONIGHT INTO EARLY WEDNESDAY. HOURLY TEMP GRIDS HAVE ALSO BEEN ADJUSTED TO SHOW A CONTINUED DECLINE UNDER CLEAR SKIES...THEN REMAIN FAIRLY STEADY OR EVEN RISE A DEGREE OR TWO FAR NORTH AS THE CLOUDS MOVE IN. CONFIDENCE IN EXTENT/COVERAGE OF STRATUS DECREASES WITH TIME...SO HAVE MAINTAINED PARTLY CLOUDY SKIES WEDNESDAY...THOUGH WOULD NOT BE SURPRISED TO SEE CLOUDS LINGER ACROSS AT LEAST THE FAR NORTHEAST PARTS OF THE FA THROUGH A PART OF WEDNESDAY MORNING. RATZER //PREV DISCUSSION... 300 PM CST AN ACTIVE PATTERN IN THE NORTHERN STREAM WILL PROVIDE SOME UPS AND DOWNS WITH TEMPERATURES FOR THE NEXT WEEK BUT VIRTUALLY NO CHANCE OF ANY DROUGHT RELIEF. TONIGHT-WEDNESDAY MAIN CONCERNS FOR OVERNIGHT INTO WEDNESDAY ARE TEMPERATURE AND CLOUD TRENDS. AREA OF STRATUS ACROSS MN-NORTHERN IA-WESTERN WIS. THIS HAS BEEN ADVECTING EAST BUT LAST FEW VISIBLE SATELLITE IMAGES SHOW SOUTHERN EDGE OF CLOUD DECK ERODING SLIGHTLY. THEREFORE THINK STRATUS WILL STAY MAINLY N OF IL...POSSIBLY JUST CLIPPING FAR NORTHERN COUNTIES AFTER MIDNIGHT. DESPITE WARM AIR ADVECTION ALOFT...EXPECT ATMOSPHERE TO DECOUPLE THIS EVENING. SHOULD BE GOOD RADIATIONAL COOLING WITH COLDEST TEMPS FAR NORTHWEST AND FAR SOUTH WHERE SNOW COVER IS IN PLACE. STRATUS COULD HAVE SOME MINOR IMPACT ON TEMPERATURES LATE TONIGHT NEAR THE WISCONSIN LINE...POSSIBLY BECOMING STEADY OR RISING A BIT TOWARD DAYBREAK. SOME SUNSHINE AND STRONG WARM AIR ADVECTION AHEAD OF APPROACHING CLIPPER WEDNESDAY SHOULD PUSH TEMPERATURES ABOVE GUIDANCE...ESPECIALLY IN LARGE SNOWLESS AREA FROM LASALLE COUNTY TO CHICAGO. CONFIDENCE HIGH. WEDNESDAY NIGHT-THURSDAY CLIPPER MOVES FROM CENTRAL CANADA TO THE NORTHERN GREAT LAKES WEDNESDAY NIGHT AND THURSDAY. SYSTEM MOVING INTO A VERY DRY AIR MASS AND BEST DYNAMICS WELL NORTH OF THE LOCAL AREA...THEREFORE ONLY EXPECT FLURRIES OR VERY LIGHT SNOW...WITH ONLY ABOUT A 20 PERCENT CHANCE OF MEASURABLE PRECIP GENERALLY NORTH OF I-80. FLURRIES MAY CONTINUE INTO THURSDAY IN COLD CYCLONIC FLOW. TEMPERATURES SHOULDN`T FALL MUCH WEDNESDAY NIGHT UNDER STRONG SOUTHWEST FLOW AND INCREASING CLOUD COVER. THEN TURNING BLUSTERY AND COLDER FOR THURSDAY. CONFIDENCE HIGH. FRIDAY-MONDAY STRONG WARM AIR ADVECTION RETURNS FRIDAY AHEAD OF NEXT CLIPPER. THIS SYSTEMS LOOKS TO BE EVEN MILDER THAN WEDNESDAY WITH 850 TEMPS OF +2 TO +4. AGAIN WILL TREND ABOVE GUIDANCE ESPECIALLY FOR AREAS WITH NO SNOW COVER. SHOULD BE NEAR OR ABOVE FREEZING FRIDAY AND MID 30S BY SATURDAY. ONLY SLIGHTLY COOLER SUNDAY BEHIND THE CLIPPER. AGAIN NO PRECIP EXPECTED WITH SATURDAYS CLIPPER. MILD DRY PATTERN CONTINUES FOR THE FIRST PART OF NEXT WEEK WITH TEMPERATURES IN THE UPPER 30S AND POSSIBLY TAGGING 40. CONFIDENCE MEDIUM-HIGH. ALLSOPP && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... * POSSIBLE MVFR CIGS TOWARD MORNING AND WEDNESDAY. CMS * POTENTIAL FOR GUSTY SOUTH/SOUTHWEST WINDS WEDNESDAY AFTERNOON. CMS //DISCUSSION...UPDATED 00Z... A LARGE AREA OF MVFR CIGS EXTENDS ACROSS NORTHERN IA INTO MN AND WESTERN WI THIS EVENING. IT HAS BEEN SLOWLY MOVING EAST AND WITH TIME MODEL HUMIDITY FIELDS WOULD SUGGEST IT MAY TURN JUST SLIGHTLY EAST/SOUTHEAST OVERNIGHT DESPITE LOW LEVEL WINDS EVENTUALLY TURNING MORE SOUTHWEST. CONFIDENCE IS FAIRLY LOW REGARDING HOW FAR SOUTHEAST THESE CLOUDS WILL MOVE AND FOR NOW HAVE OPTED TO MAINTAIN CURRENT FORECAST WITH A CIG INTO RFD TOWARD MIDNIGHT AND THEN SCATTERED MENTION ELSEWHERE PRIOR TO SUNRISE. HOPEFULLY TRENDS WILL BECOME MORE CLEAR THROUGH THE EVENING. REGARDLESS OF WHAT THESE CLOUDS DO...WITH THE WINDS TURNING MORE SOUTHWESTERLY OVERNIGHT AND SOUTHERLY WEDNESDAY...EXPECTED ADDITIONAL HIGH MVFR OR LOW VFR...3-4KFT CIGS TO DEVELOP AND LIKELY LOWER TO MVFR INTO WEDNESDAY EVENING. WEST/NORTHWEST WINDS 10KTS OR LESS WILL SLOWLY TURN SOUTHWESTERLY THROUGH THE NIGHT AND BECOME MORE SOUTHERLY BY MORNING. DEPENDING ON THE AMOUNT OF CLOUD COVER ON WEDNESDAY...THE POTENTIAL EXISTS FROM SOME GUSTS BY LATE MORNING AND IN THE AFTERNOON...BUT ONLY IN THE MID/UPPER TEEN KT RANGE. CMS //ORD AND MDW CONFIDENCE...UPDATED 03Z... * LOW CONFIDENCE REGARDING MVFR CIGS OVERNIGHT AND WEDNESDAY. * MEDIUM CONFIDENCE REGARDING WINDS THROUGH THE PERIOD. CMS //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... * THURSDAY...OCCASIONAL FLURRIES. MVFR POSSIBLE. * FRIDAY THROUGH MONDAY...DRY. VFR. && .MARINE... 202 PM CST I ISSUED A SMALL CRAFT ADVISORY EARLIER THIS MORNING FOR THE INDIANA SHORES DUE TO NORTHWESTERLY WINDS OF 20 TO 25 KT AND BUILDING WAVES UP TO 4 TO 6 FT. THE WINDS HAVE BEEN SLOWLY DIMINISHING OVER THE PAST COUPLE OF HOURS...WITH WINDS OUT OF THE NORTHWEST IN THE 15 TO 20 KT RANGE. I WILL KEEP THIS ADVISORY GOING THROUGH MOST OF TONIGHT AS WAVES WILL LIKELY BE SLOW TO SUBSIDE BELOW 4 FEET. OTHERWISE...THE MAIN CONCERNS OVER THE LAKE WILL BE ON THURSDAY THROUGH FRIDAY AS THE ANOTHER EPISODE OF HIGH WINDS IS EXPECTED. ON THURSDAY...A POTENT AREA OF HIGH PRESSURE IS EXPECTED TO BUILD ACROSS THE CENTRAL AND SOUTHERN PLAINS...EASTWARD ACROSS THE MIDDLE MISSISSIPPI VALLEY. AT THE SAME TIME...AN AREA OF LOW PRESSURE WILL TRACK EASTWARD ACROSS THE UPPER GREAT LAKES. THESE TWO PRESSURE SYSTEMS WILL RESULT IN A DECENT PRESSURE GRADIENT ACROSS THE LAKE LATER THURSDAY...LIKELY RESULTING IN AN UPTAKE IN THE WIND SPEEDS AS THEY BECOME WESTERLY. AT THIS TIME IT APPEARS THE WINDS WILL BE AROUND 30 KT. HOWEVER...I CANNOT RULE OUT A FEW GALES...SO I WILL CONTINUE TO THE MENTION. THE WINDS DONT LOOK TO DIMINISH MUCH INTO FRIDAY AS ANOTHER WEAK TROUGH OF LOW PRESSURE TRACKS TO THE NORTH...ESSENTIALLY MAINTAINING THE STRENGTH OF THE GRADIENT. FROM SATURDAY INTO NEXT WEEK IT APPEARS THE WEATHER PATTERN ACROSS THE UPPER MIDWEST AND UPPER GREAT LAKES WILL REMAIN VERY ACTIVE. IN FACT...IT APPEARS A PARADE OF LOW PRESSURE SYSTEMS WILL CONTINUE TO TRACK ACROSS THE UPPER GREAT LAKES EVERY DAY OR TWO THROUGH AT LEAST THE MIDDLE OF NEXT WEEK AS HIGH PRESSURE DOMINATES ACROSS THE SOUTHERN CONUS. OVERALL THIS LOOKS TO RESULT IN A FAIRLY PROLONGED PERIOD OF ELEVATED WEST TO SOUTHWESTERLY WINDS OF 25 TO 30 KT THROUGH MUCH OF THE PERIOD. THERE COULD ALSO BE A FEW PERIODS OF GALE FORCE WINDS DURING THE PERIOD. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
811 PM CST TUE JAN 1 2013 .DISCUSSION... 811 PM CST FOR EVENING UPDATE... HAVE TWEAKED GOING FORECAST FOR TONIGHT MAINLY TO LOWER MIN TEMPS 1-3 DEGREES MOST AREAS AND ESPECIALLY NORTHWEST...AND TO INCREASE SKY COVER AFTER MIDNIGHT ACROSS THE FAR NORTH. EARLY EVENING ANALYSIS PLACES SURFACE HIGH PRESSURE FROM THE SOUTHERN PLAINS INTO THE MID-MISSISSIPPI RIVER VALLEY. NORTHEAST EXTENT OF SURFACE RIDGE AXIS EXTENDS INTO NORTHERN IL...WHERE CLEAR SKIES WERE ALLOWING STRONG RADIATIONAL COOLING AS WINDS DECOUPLE IN/NEAR THE RIDGE AXIS. BASED ON THESE TRENDS HAVE LOWERED TEMPS ACROSS MUCH OF THE AREA BY UP TO SEVERAL DEGREES...CLOSER TO SOME OF THE COOLER MOS GUIDANCE FROM 12/18Z. OTHER FACTOR OF NOTE THIS EVENING IS THE AREA OF STRATUS OVER MUCH OF THE UPPER MISSISSIPPI VALLEY...WHICH HAS BEEN DRIFTING EAST DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. STOUT LOW LEVEL INVERSION ASSOCIATED WITH MODIFIED-ARCTIC AIR AND DENSE SNOW PACK ACROSS AREAS WEST/NORTHWEST OF THE CWA WAS NOTED IN 12Z RAOBS FROM UPSTREAM LOCATIONS. 21-00Z RAP FORECASTS OF 950-900 MB LAYER RH SEEM TO CAPTURE THE EXTENT OF THE STRATUS FAIRLY WELL...AND SUGGEST THAT THESE CLOUDS WILL SPREAD EAST INTO FAR NORTHERN IL AFTER MIDNIGHT AND PERHAPS EVEN SHIFT A LITTLE SOUTHEAST THROUGH EARLY WEDNESDAY MORNING. OTHER GUIDANCE HAS NOT HANDLED THE EXTENT/ADVECTION OF THE STRATUS VERY WELL. BASED ON SATELLITE TRENDS AND THE RAP FORECASTS...WHICH SEEM REASONABLE GIVEN THIS MOISTURE TRAPPED WITHIN STABLE LOW LEVELS...HAVE INCREASED CLOUD COVER OVER FAR NORTHERN IL LATE TONIGHT INTO EARLY WEDNESDAY. HOURLY TEMP GRIDS HAVE ALSO BEEN ADJUSTED TO SHOW A CONTINUED DECLINE UNDER CLEAR SKIES...THEN REMAIN FAIRLY STEADY OR EVEN RISE A DEGREE OR TWO FAR NORTH AS THE CLOUDS MOVE IN. CONFIDENCE IN EXTENT/COVERAGE OF STRATUS DECREASES WITH TIME...SO HAVE MAINTAINED PARTLY CLOUDY SKIES WEDNESDAY...THOUGH WOULD NOT BE SURPRISED TO SEE CLOUDS LINGER ACROSS AT LEAST THE FAR NORTHEAST PARTS OF THE FA THROUGH A PART OF WEDNESDAY MORNING. RATZER && .PREV DISCUSSION... 300 PM CST AN ACTIVE PATTERN IN THE NORTHERN STREAM WILL PROVIDE SOME UPS AND DOWNS WITH TEMPERATURES FOR THE NEXT WEEK BUT VIRTUALLY NO CHANCE OF ANY DROUGHT RELIEF. TONIGHT-WEDNESDAY MAIN CONCERNS FOR OVERNIGHT INTO WEDNESDAY ARE TEMPERATURE AND CLOUD TRENDS. AREA OF STRATUS ACROSS MN-NORTHERN IA-WESTERN WIS. THIS HAS BEEN ADVECTING EAST BUT LAST FEW VISIBLE SATELLITE IMAGES SHOW SOUTHERN EDGE OF CLOUD DECK ERODING SLIGHTLY. THEREFORE THINK STRATUS WILL STAY MAINLY N OF IL...POSSIBLY JUST CLIPPING FAR NORTHERN COUNTIES AFTER MIDNIGHT. DESPITE WARM AIR ADVECTION ALOFT...EXPECT ATMOSPHERE TO DECOUPLE THIS EVENING. SHOULD BE GOOD RADIATIONAL COOLING WITH COLDEST TEMPS FAR NORTHWEST AND FAR SOUTH WHERE SNOW COVER IS IN PLACE. STRATUS COULD HAVE SOME MINOR IMPACT ON TEMPERATURES LATE TONIGHT NEAR THE WISCONSIN LINE...POSSIBLY BECOMING STEADY OR RISING A BIT TOWARD DAYBREAK. SOME SUNSHINE AND STRONG WARM AIR ADVECTION AHEAD OF APPROACHING CLIPPER WEDNESDAY SHOULD PUSH TEMPERATURES ABOVE GUIDANCE...ESPECIALLY IN LARGE SNOWLESS AREA FROM LASALLE COUNTY TO CHICAGO. CONFIDENCE HIGH. WEDNESDAY NIGHT-THURSDAY CLIPPER MOVES FROM CENTRAL CANADA TO THE NORTHERN GREAT LAKES WEDNESDAY NIGHT AND THURSDAY. SYSTEM MOVING INTO A VERY DRY AIR MASS AND BEST DYNAMICS WELL NORTH OF THE LOCAL AREA...THEREFORE ONLY EXPECT FLURRIES OR VERY LIGHT SNOW...WITH ONLY ABOUT A 20 PERCENT CHANCE OF MEASURABLE PRECIP GENERALLY NORTH OF I-80. FLURRIES MAY CONTINUE INTO THURSDAY IN COLD CYCLONIC FLOW. TEMPERATURES SHOULDN`T FALL MUCH WEDNESDAY NIGHT UNDER STRONG SOUTHWEST FLOW AND INCREASING CLOUD COVER. THEN TURNING BLUSTERY AND COLDER FOR THURSDAY. CONFIDENCE HIGH. FRIDAY-MONDAY STRONG WARM AIR ADVECTION RETURNS FRIDAY AHEAD OF NEXT CLIPPER. THIS SYSTEMS LOOKS TO BE EVEN MILDER THAN WEDNESDAY WITH 850 TEMPS OF +2 TO +4. AGAIN WILL TREND ABOVE GUIDANCE ESPECIALLY FOR AREAS WITH NO SNOW COVER. SHOULD BE NEAR OR ABOVE FREEZING FRIDAY AND MID 30S BY SATURDAY. ONLY SLIGHTLY COOLER SUNDAY BEHIND THE CLIPPER. AGAIN NO PRECIP EXPECTED WITH SATURDAYS CLIPPER. MILD DRY PATTERN CONTINUES FOR THE FIRST PART OF NEXT WEEK WITH TEMPERATURES IN THE UPPER 30S AND POSSIBLY TAGGING 40. CONFIDENCE MEDIUM-HIGH. ALLSOPP && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * POSSIBLE MVFR CIGS OVERNIGHT AND WEDNESDAY. CMS * POTENTIAL FOR GUSTY SOUTH/SOUTHWEST WINDS WEDNESDAY AFTERNOON. CMS //DISCUSSION...UPDATED 00Z... A LARGE AREA OF MVFR CIGS EXTENDS ACROSS NORTHERN IA INTO MN AND WESTERN WI THIS EVENING. IT HAS BEEN SLOWLY MOVING EAST AND WITH TIME MODEL HUMIDITY FIELDS WOULD SUGGEST IT MAY TURN JUST SLIGHTLY EAST/SOUTHEAST OVERNIGHT DESPITE LOW LEVEL WINDS EVENTUALLY TURNING MORE SOUTHWEST. CONFIDENCE IS FAIRLY LOW REGARDING HOW FAR SOUTHEAST THESE CLOUDS WILL MOVE AND FOR NOW HAVE OPTED TO MAINTAIN CURRENT FORECAST WITH A CIG INTO RFD TOWARD MIDNIGHT AND THEN SCATTERED MENTION ELSEWHERE PRIOR TO SUNRISE. HOPEFULLY TRENDS WILL BECOME MORE CLEAR THROUGH THE EVENING. REGARDLESS OF WHAT THESE CLOUDS DO...WITH THE WINDS TURNING MORE SOUTHWESTERLY OVERNIGHT AND SOUTHERLY WEDNESDAY...EXPECTED ADDITIONAL HIGH MVFR OR LOW VFR...3-4KFT CIGS TO DEVELOP AND LIKELY LOWER TO MVFR INTO WEDNESDAY EVENING. WEST/NORTHWEST WINDS 10KTS OR LESS WILL SLOWLY TURN SOUTHWESTERLY THROUGH THE NIGHT AND BECOME MORE SOUTHERLY BY MORNING. DEPENDING ON THE AMOUNT OF CLOUD COVER ON WEDNESDAY...THE POTENTIAL EXISTS FROM SOME GUSTS BY LATE MORNING AND IN THE AFTERNOON...BUT ONLY IN THE MID/UPPER TEEN KT RANGE. CMS //ORD AND MDW CONFIDENCE...UPDATED 00Z... * LOW CONFIDENCE REGARDING MVFR CIGS OVERNIGHT AND WEDNESDAY. * MEDIUM CONFIDENCE REGARDING WINDS THROUGH THE PERIOD. CMS //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... * THURSDAY...OCCASIONAL FLURRIES. MVFR POSSIBLE. * FRIDAY THROUGH MONDAY...DRY. VFR. && .MARINE... 202 PM CST I ISSUED A SMALL CRAFT ADVISORY EARLIER THIS MORNING FOR THE INDIANA SHORES DUE TO NORTHWESTERLY WINDS OF 20 TO 25 KT AND BUILDING WAVES UP TO 4 TO 6 FT. THE WINDS HAVE BEEN SLOWLY DIMINISHING OVER THE PAST COUPLE OF HOURS...WITH WINDS OUT OF THE NORTHWEST IN THE 15 TO 20 KT RANGE. I WILL KEEP THIS ADVISORY GOING THROUGH MOST OF TONIGHT AS WAVES WILL LIKELY BE SLOW TO SUBSIDE BELOW 4 FEET. OTHERWISE...THE MAIN CONCERNS OVER THE LAKE WILL BE ON THURSDAY THROUGH FRIDAY AS THE ANOTHER EPISODE OF HIGH WINDS IS EXPECTED. ON THURSDAY...A POTENT AREA OF HIGH PRESSURE IS EXPECTED TO BUILD ACROSS THE CENTRAL AND SOUTHERN PLAINS...EASTWARD ACROSS THE MIDDLE MISSISSIPPI VALLEY. AT THE SAME TIME...AN AREA OF LOW PRESSURE WILL TRACK EASTWARD ACROSS THE UPPER GREAT LAKES. THESE TWO PRESSURE SYSTEMS WILL RESULT IN A DECENT PRESSURE GRADIENT ACROSS THE LAKE LATER THURSDAY...LIKELY RESULTING IN AN UPTAKE IN THE WIND SPEEDS AS THEY BECOME WESTERLY. AT THIS TIME IT APPEARS THE WINDS WILL BE AROUND 30 KT. HOWEVER...I CANNOT RULE OUT A FEW GALES...SO I WILL CONTINUE TO THE MENTION. THE WINDS DONT LOOK TO DIMINISH MUCH INTO FRIDAY AS ANOTHER WEAK TROUGH OF LOW PRESSURE TRACKS TO THE NORTH...ESSENTIALLY MAINTAINING THE STRENGTH OF THE GRADIENT. FROM SATURDAY INTO NEXT WEEK IT APPEARS THE WEATHER PATTERN ACROSS THE UPPER MIDWEST AND UPPER GREAT LAKES WILL REMAIN VERY ACTIVE. IN FACT...IT APPEARS A PARADE OF LOW PRESSURE SYSTEMS WILL CONTINUE TO TRACK ACROSS THE UPPER GREAT LAKES EVERY DAY OR TWO THROUGH AT LEAST THE MIDDLE OF NEXT WEEK AS HIGH PRESSURE DOMINATES ACROSS THE SOUTHERN CONUS. OVERALL THIS LOOKS TO RESULT IN A FAIRLY PROLONGED PERIOD OF ELEVATED WEST TO SOUTHWESTERLY WINDS OF 25 TO 30 KT THROUGH MUCH OF THE PERIOD. THERE COULD ALSO BE A FEW PERIODS OF GALE FORCE WINDS DURING THE PERIOD. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
543 AM CST MON DEC 31 2012 .UPDATE... RECENT RAP TRENDS GENERALLY INDICATE THE EARLIER THINKING IS ON TRACK. THERE IS A PRE-FRONTAL TROF IMMEDIATELY AHEAD OF THE COLD FRONT WITH THE TROF ALONG THE MISSISSIPPI RIVER. CURRENT RADAR RETURNS ARE MID LEVEL CLOUDS BEING PICKED UP. A MINOR FRESHENING OF THE FCST WILL BE DONE SHORTLY TO BETTER REFLECT THE FRONTAL PLACEMENT AND RECENT TEMPERATURE TRENDS. TEMPERATURES TODAY SHOULD BE STEADY OVER MOST OF THE CWFA WITH A STEADY OR SLOW FALL ACROSS THE SOUTHEAST THIRD TO 40 PERCENT OF THE CWFA. ..08.. && .AVIATION... THE FRONT HAS GONE THROUGH KCID AND IS CURRENTLY GOING THROUGH KDBQ. A SUBTLE PRE-FRONTAL TROF IS IMMEDIATELY AHEAD OF THE FRONT BUT BOTH WILL BE GOING THROUGH KMLI/KBRL BY 14Z/31. KCID/KDBQ CONTINUE TO HAVE A SCATTERED 1-2KFT AGL LAYER IN THE 12Z TAFS. IF THE RAP MODEL TRENDS ARE CORRECT...THERE MAY BE A THREAT OF MVFR OR IFR CIGS AT KDBQ AROUND 18Z/31. KBRL WILL BE IMPACTED BY THE STORM MOVING INTO THE OHIO VALLEY WITH MVFR CONDITIONS DVLPG WITH A POTENTIAL FOR A PERIOD OF IFR CONDITIONS AFT 18Z/31. ..08.. && .PREV DISCUSSION... /ISSUED 315 AM CST MON DEC 31 2012/ SYNOPSIS... 06Z SFC ANALYSIS HAS A WEAK LOW NORTH OF KLSE WITH A WARM FRONT THROUGH SOUTHERN WISCONSIN. A COLD FRONT RAN FROM THE LOW TO ANOTHER LOW IN SOUTHEAST COLORADO. THERE WAS A SUBTLE PRE-FRONTAL TROF FROM THE LOW INTO EASTERN KANSAS. A SECONDARY ARCTIC FRONT RAN FROM WESTERN LAKE SUPERIOR INTO SOUTH DAKOTA. DEW POINTS WERE IN THE TEENS AND 20S ACROSS THE MIDWEST WITH 30S IN THE SOUTHERN PLAINS AND DEEP SOUTH. SHORT TERM...TODAY AND TONIGHT... TIMING AND NORTHERN EXTENT OF THE SNOW ARE THE MAIN QUESTIONS. BASED ON DATA THROUGH 06Z...THE RAP MODEL SEEMS TO HAVE A MORE REALISTIC REPRESENTATION OF WHAT IS CURRENTLY GOING ON. PER THE RAP MODEL...CONDENSATION PRESSURE DEFICITS BEGIN COLLAPSING ACROSS THE FAR SOUTH RIGHT AROUND SUNRISE IN THE 850-700MB LAYER. HOWEVER... CONDENSATION PRESSURE DEFICITS IN THE 1000-850MB LAYER DO NOT COLLAPSE UNTIL MID MORNING. SO...WILL GO WITH THE IDEA OF SCHC/CHC POPS ACROSS THE EXTREME SOUTH FOR THE MORNING COMMUTE WITH A BAND OF FLURRIES IMMEDIATELY NORTH OF THERE. BY MID TO LATE MORNING -SN WILL QUICKLY BREAK OUT ACROSS THE FAR SOUTHERN CWFA AND EXPAND 15-30 MILES NORTHWARD DURING THE EARLY AFTERNOON HOURS. LIKELY TO CATEGORICAL POPS LOOK REASONABLE GENERALLY SOUTH OF A KPIA TO KTVK LINE WITH SCHC/CHC POPS UP AS FAR NORTH AS A KOTM TO KVYS LINE. DURING THE EARLY AFTERNOON HOURS THE RAP MODEL SHOWS A NEW BAND OF FORCING DEVELOPING ALONG THE I-80 CORRIDOR WITH SOME MOISTURE CONVERGENCE. FCST SOUNDINGS IN THIS AREA STILL SHOW AN APPRECIABLE AMOUNT OF DRY AIR IN THE LOWER LEVELS SO SOME FLURRIES MAY BE POSSIBLE. BY LATE AFTERNOON THE FORCING BEGINS PUSHING TO THE SOUTH/EAST SO THE SNOW SHOULD MIGRATE ABOUT 20-30 MILES TO THE SOUTH. AS FOR AMOUNTS...THE EXTREME SOUTHERN BORDER AREA OF THE CWFA SHOULD SEE AROUND AN INCH. A DUSTING WILL BE POSSIBLE AS FAR NORTH AS A KOTM TO KGBG LINE. TONIGHT...LIGHT SNOW WILL CONTINUE INTO THE EVENING HOURS BUT WILL SLOWLY DECREASE IN COVERAGE/INTENSITY. AFTER MIDNIGHT...THE FORCING CONTINUES TO WEAKEN AS THE SYSTEM MOVES INTO THE OHIO VALLEY SO THE LIGHT SNOW WILL SLOWLY COME TO AN END. ANY ADDITIONAL AMOUNTS TONIGHT WILL ONLY BE A TRACE TO A DUSTING. 08 LONG TERM...TUESDAY THROUGH NEXT SUNDAY... COLD AND DRY WITH WARMING TREND STARTING NEXT WEEKEND. OVERVIEW...INITIALIZATION IS GOOD WITH MOST SOLUTIONS A BIT TOO MOIST WITH TODAY/S SYSTEM. UPSTREAM...NO SENSIBLE WEATHER ISSUES. RUN TO RUN CONTINUITY SUGGEST A 80/20 BLEND OF HI-RES ECMWF/GFS THERMAL FIELDS. ADD TONIGHT/S VERIFICATION AND RECENT PERSISTENCE SUPPORT WHEN SKIES ARE FAIR FOR SLIGHTLY HIGHER MAX/S THAN HIGHEST GUIDANCE AND WITH LIGHT WINDS...MINS LOWER THAN COLDEST GUIDANCE. TUESDAY THROUGH SUNDAY...MINOR CHANGES OF A DEGREE OR TWO MADE. QUIET PATTERN...NEXT UPPER TROUGH AND MORE COLD AIR STILL SCHEDULED TO ARRIVE LATE WEDNESDAY AND THURSDAY WITH POSSIBLE FLURRIES FOR LATER SHIFTS. LOCAL BL TOOLS SUGGEST TEMPERATURES MAY NEED RAISING BY A CATEGORY SATURDAY ONWARD. NICHOLS && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
315 AM CST MON DEC 31 2012 .SYNOPSIS... 06Z SFC ANALYSIS HAS A WEAK LOW NORTH OF KLSE WITH A WARM FRONT THROUGH SOUTHERN WISCONSIN. A COLD FRONT RAN FROM THE LOW TO ANOTHER LOW IN SOUTHEAST COLORADO. THERE WAS A SUBTLE PRE-FRONTAL TROF FROM THE LOW INTO EASTERN KANSAS. A SECONDARY ARCTIC FRONT RAN FROM WESTERN LAKE SUPERIOR INTO SOUTH DAKOTA. DEW POINTS WERE IN THE TEENS AND 20S ACROSS THE MIDWEST WITH 30S IN THE SOUTHERN PLAINS AND DEEP SOUTH. && .SHORT TERM...TODAY AND TONIGHT... TIMING AND NORTHERN EXTENT OF THE SNOW ARE THE MAIN QUESTIONS. BASED ON DATA THROUGH 06Z...THE RAP MODEL SEEMS TO HAVE A MORE REALISTIC REPRESENTATION OF WHAT IS CURRENTLY GOING ON. PER THE RAP MODEL...CONDENSATION PRESSURE DEFICITS BEGIN COLLAPSING ACROSS THE FAR SOUTH RIGHT AROUND SUNRISE IN THE 850-700MB LAYER. HOWEVER... CONDENSATION PRESSURE DEFICITS IN THE 1000-850MB LAYER DO NOT COLLAPSE UNTIL MID MORNING. SO...WILL GO WITH THE IDEA OF SCHC/CHC POPS ACROSS THE EXTREME SOUTH FOR THE MORNING COMMUTE WITH A BAND OF FLURRIES IMMEDIATELY NORTH OF THERE. BY MID TO LATE MORNING -SN WILL QUICKLY BREAK OUT ACROSS THE FAR SOUTHERN CWFA AND EXPAND 15-30 MILES NORTHWARD DURING THE EARLY AFTERNOON HOURS. LIKELY TO CATEGORICAL POPS LOOK REASONABLE GENERALLY SOUTH OF A KPIA TO KTVK LINE WITH SCHC/CHC POPS UP AS FAR NORTH AS A KOTM TO KVYS LINE. DURING THE EARLY AFTERNOON HOURS THE RAP MODEL SHOWS A NEW BAND OF FORCING DEVELOPING ALONG THE I-80 CORRIDOR WITH SOME MOISTURE CONVERGENCE. FCST SOUNDINGS IN THIS AREA STILL SHOW AN APPRECIABLE AMOUNT OF DRY AIR IN THE LOWER LEVELS SO SOME FLURRIES MAY BE POSSIBLE. BY LATE AFTERNOON THE FORCING BEGINS PUSHING TO THE SOUTH/EAST SO THE SNOW SHOULD MIGRATE ABOUT 20-30 MILES TO THE SOUTH. AS FOR AMOUNTS...THE EXTREME SOUTHERN BORDER AREA OF THE CWFA SHOULD SEE AROUND AN INCH. A DUSTING WILL BE POSSIBLE AS FAR NORTH AS A KOTM TO KGBG LINE. TONIGHT...LIGHT SNOW WILL CONTINUE INTO THE EVENING HOURS BUT WILL SLOWLY DECREASE IN COVERAGE/INTENSITY. AFTER MIDNIGHT...THE FORCING CONTINUES TO WEAKEN AS THE SYSTEM MOVES INTO THE OHIO VALLEY SO THE LIGHT SNOW WILL SLOWLY COME TO AN END. ANY ADDITIONAL AMOUNTS TONIGHT WILL ONLY BE A TRACE TO A DUSTING. 08 .LONG TERM...TUESDAY THROUGH NEXT SUNDAY... COLD AND DRY WITH WARMING TREND STARTING NEXT WEEKEND. OVERVIEW...INITIALIZATION IS GOOD WITH MOST SOLUTIONS A BIT TOO MOIST WITH TODAY/S SYSTEM. UPSTREAM...NO SENSIBLE WEATHER ISSUES. RUN TO RUN CONTINUITY SUGGEST A 80/20 BLEND OF HI-RES ECMWF/GFS THERMAL FIELDS. ADD TONIGHT/S VERIFICATION AND RECENT PERSISTENCE SUPPORT WHEN SKIES ARE FAIR FOR SLIGHTLY HIGHER MAX/S THAN HIGHEST GUIDANCE AND WITH LIGHT WINDS...MINS LOWER THAN COLDEST GUIDANCE. TUESDAY THROUGH SUNDAY...MINOR CHANGES OF A DEGREE OR TWO MADE. QUIET PATTERN...NEXT UPPER TROUGH AND MORE COLD AIR STILL SCHEDULED TO ARRIVE LATE WEDNESDAY AND THURSDAY WITH POSSIBLE FLURRIES FOR LATER SHIFTS. LOCAL BL TOOLS SUGGEST TEMPERATURES MAY NEED RAISING BY A CATEGORY SATURDAY ONWARD. NICHOLS && .AVIATION... SFC COLD FRONT MOVING THROUGH CENTRAL IA WILL PASS THROUGH THE TERMINALS BETWEEN 08Z-14Z. GUSTY SOUTH WINDS 10-20+ KTS TO SHIFT TO W/NW WITH FRONTAL PASSAGE. KDVN WSR-88D VWP SHOWING WINDS AT 45 KTS AROUND 2000 FT AGL BUT OVERALL WINDS WILL BE DECREASING ALOFT IN THE NEXT FEW HRS WITH FRONT MOVING IN AND WITH THIS ALONG WITH GUSTY SFC WINDS HAVE OPTED TO NO LONGER MENTION LLWS MENTION WITH 06Z TAFS. SATELLITE AND OBS SHOW LOW CLOUDS OVER PORTIONS OF DAKOTAS INTO MN TRAILING WELL BEHIND SFC COLD FRONT. THERE IS A LOT OF UNCERTAINTY ON THE EVOLUTION OF THESE CLOUDS AS SOME SHORT RANGE GUIDANCE CONTINUES TO SUGGEST INCOMING SUBSIDENCE TO ERODE AS THEY APPROACH. OVERALL... WHILE MAY SEE SOME MVFR CIGS DURING DAY ON MON... JUST NOT CONFIDENT ON WHERE AND FOR HOW LONG... SO HAVE JUST CONTINUED WITH SCATTERED MVFR BASES TO HINT AT POTENTIAL AND LET LATER SHIFTS EVALUATE TRENDS. OTHER CONCERN WITH 06Z TAFS IS -SN POTENTIAL MAINLY AT KBRL... AS STORM SYSTEM EJECTS FROM THE SOUTHERN PLAINS AND SPREADS PCPN INTO NORTHEAST MO... WEST CENTRAL IL AND FAR SOUTHEAST IA. FCST SOUNDINGS SHOW A LOT OF DRY AIR TO OVERCOME AT KBRL BUT SUFFICIENT LIFT FOR A CHANCE OF PERIOD OF -SN WITH MVFR CONDITIONS AT KBRL FROM LATE AM THROUGH EARLY PM. OTHERWISE... MAINLY JUST FLURRIES AT KBRL WITH VSBYS AT OR ABOVE 6SM... WITH LOW PROBABILITY OF -FZDZ. 05 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ 08/NICHOLS/05
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
400 AM CST MON DEC 31 2012 .DISCUSSION... A COLD FRONT HAS PASSED ACROSS THE FORECAST AREA THIS MORNING...WITH BRISK NORTHWEST WINDS AND FAIRLY WIDESPREAD STRATUS CLOUDS NOTED IN ITS WAKE. AN ATYPICAL TEMPERATURE TREND WILL ENSUE TODAY...WITH READINGS EXPECTED TO FALL THROUGHOUT THE MORNING...AND THEN ONLY WARM A COUPLE DEGREES OR REMAIN STEADY THIS AFTERNOON. ATTENTION THEN TURNS TO TONIGHT...AS NEW YEARS EVE-GOERS ARE MET WITH VERY COLD TEMPERATURES UNDER THE MOSTLY CLEAR SKIES ATTENDANT WITH THE SURFACE RIDGE. WHILE WIND SPEEDS ARE BORDERLINE AND VALUES ARE MARGINAL OVER SOUTHERN MN...IT/S CLOSE ENOUGH TO WARRANT ISSUANCE OF A WIND CHILL ADVISORY GIVEN THE SENSITIVITY AROUND A HOLIDAY TIME PERIOD. MAX TEMPERATURES ON TUESDAY WILL RANK WITHIN THE COLDEST 15 PERCENT OF NEW YEARS DAYS HIGHS IN MANY LOCATIONS...WITH HIGHS ONLY EXPECTED TO RANGE BETWEEN 9 AND 15 DEGREES. WEDNESDAY WILL BRING THE NEXT CHANCE OF MEASURABLE SNOW...ALBEIT ONLY HALF INCH OR LOWER AMOUNTS...AS AN UPPER LOW DROPS SOUTH FROM MANTIOBA/SASKATCHEWAN. A FAIRLY DECENT PV ACVECTION SIGNATURE AND 275K ISENTROPIC LIFT ARE NOTED ON WEDNESDAY...ESPECIALLY ACROSS WEST CENTRAL MN WHERE HIGH CHANCE POPS HAVE BEEN MAINTAINED. THURSDAY INTO THE WEEKEND WILL BRING MODERATING TEMPERATURES AS A MID/UPPER RIDGE BUILDS OVER THE WESTERN HALF OF THE CONUS. HIGH TEMPERATURES WILL WARM INTO THE 20S AND 30S FOR FRIDAY THROUGH THE WEEKEND. && .AVIATION.../00Z TAF ISSUANCE/ STRATUS BEHIND COLD FRONT IS HEALTHIEST IN WESTERN MN...AND MORE SCATTERED FROM CENTRAL INTO NERN MN. SIGNIFICANT SURGE OF DRY AIR CONTINUES TO MOVE THROUGH NWRN MN. LATEST RAP DOES A GOOD JOB LATCHING ONTO THIS. BOTTOM LINE IS THAT EASTERN MN AND WESTERN WISC WILL BE IN AND OUT OF THE STRATUS THROUGH THE NIGHT. WESTERN MN SITES AXN/RWF ARE MORE LIKELY TO SEE PERSISTENT STRATUS FOR MOST OF THE NIGHT BUT EVEN THOSE LOCATIONS WILL SEE SOME POCKETS OF SCATTERED CLOUDS. MUCH DRIER AIR FROM NWRN MN SHOULD ARRIVE 10Z- 14Z FROM NORTHWEST TO SOUTHEAST...BRINGING SKC OR FEW CLOUDS. ONLY OTHER ISSUE WILL BE GUSTY WINDS REACHING 20 KNOTS AT TIMES BEFORE SETTLING DOWN AS SURFACE HIGH BUILDS IN LATE MONDAY AFTERNOON. KMSP...STRATUS IS QUITE PPATCHY AND KMSP WILL BE VARYING BETWEEN OVC AND SCT AT TIMES THROUGH AT LEAST 11Z AND MAYBE EVEN 14Z. SHOULD BE MOSTLY CLEAR THEREAFTER WITH INCOMING DRY AIR FROM NORTHWEST. NW WINDS WITH SOME GUSTS NEAR 20 KTS MONDAY MORNING WITH COLD ADVECTION. /OUTLOOK FOR KMSP/ TUE...VFR. SW WINDS 5-10 KNOTS. WED...MVFR CONDITIONS/-SN. SW WINDS 5-10 KNOTS BECOMING NW. THU...VFR. NW WINDS 5-10 KNOTS BECOMING W. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WIND CHILL ADVISORY FROM 10 PM THIS EVENING TO 9 AM CST TUESDAY FOR BLUE EARTH-BROWN-CHIPPEWA-DOUGLAS-FARIBAULT-FREEBORN- GOODHUE-KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD- MEEKER-NICOLLET-POPE-REDWOOD-RENVILLE-RICE-SIBLEY-STEARNS- STEELE-STEVENS-SWIFT-TODD-WASECA-WATONWAN-YELLOW MEDICINE. WI...NONE. && $$ LS/TDK
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1159 PM CST SUN DEC 30 2012 .UPDATE... UPDATED FOR AVIATION DISCUSSION BELOW. && .DISCUSSION... /ISSUED 216 PM CST SUN DEC 30 2012/ OVERVIEW...COLD TEMPERATURES EXPECTED THROUGH THE NEW YEAR WITH GRADUAL WARMING LATE THIS WEEK. NEAR NORMAL TEMPS BY NEXT WEEKEND. CHANCE OF LIGHT SNOW REMAINS IN THE FORECAST FOR WEDNESDAY AS CLIPPER SYSTEM DROPS SOUTH ACROSS THE AREA. ARCTIC FRONT IS NOW STRETCHED OUT ACROSS THE EASTERN DAKOTAS AND DOWN INTO EASTERN NEBRASKA. STRONG SOUTHWESTERLY FLOW HAS WARMED WESTERN IA AND EASTERN NE INTO THE 30S AND 40S. THE FLOW REMAINS MORE SOUTHEAST HERE AND A THICK CANOPY OF CIRRUS ASSOCIATED WITH THE JET IS SLOWING THE TEMPERATURE RISE IN MN/WI. COLD FRONT AND WEAK SURFACE TROUGH MOVE THROUGH LATE THIS EVENING...AND COULD PROVIDE MORE LOW CLOUDS TO FAR EASTERN MN AND WESTERN WI. THERE IS A SMALL CHANCE FOR FLURRIES OR EVEN A LIGHT PATCHY FREEZING DRIZZLE GIVEN THE SATURATION DOWN LOW. HOWEVER...WE`RE NOT EVEN COMPLETELY CONFIDENT IN CLOUD COVER...LET ALONG SHAKING OUT DRIZZLE/FLURRIES. THE ISENTROPIC SURFACES AREN`T AS QUICK TO SATURATE TONIGHT COMPARED TO WHAT THE NAM/GFS WAS SHOWING YESTERDAY. ALSO...THE LOWEST CONDENSATION PRESSURE DEFICITS ARE LOWEST RIGHT ALONG OR JUST BEHIND THE ARCTIC BOUNDARY IN AN AREA OF COLD AIR ADVECTION. TYPICALLY IF WE ARE GOING TO GET DRIZZLE...IT WOULD HAPPEN OUT AHEAD OF THE FRONT WHERE THERE IS WARM AIR/MOISTURE ADVECTION AND ISENTROPIC LIFT. SO...WE LEFT ANY PRECIP OUT OF THE FORECAST TONIGHT...BUT DID INCREASE CLOUD COVER IN EASTERN MN AND WI. THE FRONT SHOULD LEAD TO A NON DIURNAL TREND WITH THE TEMPERATURES TOMORROW WHERE WE SHOULD COOL DURING THE DAY AND WILL LIKELY SEE OUR HIGHS IN THE MORNING. STILL FAVORING A EC/NAM BLEND IN TEMPERATURES ON NEW YEARS EVE...WITH THE GEM LIKELY TOO COLD AND THE GFS LIKELY TOO WARM. THE GEM WOULD SUGGEST -15 TO -23...AND OUR FORECAST IS MORE IN THE -8 TO -17 RANGE. THE WIND ISN`T VERY STRONG BY THE TIME THE COLDEST TEMPS SETTLE IN AFTER 06Z ON JAN. 1...BUT APPARENT TEMPS STILL LOOK COLD ENOUGH FOR A WIND CHILL ADVISORY MONDAY NIGHT INTO TUESDAY MORNING. CLIPPER SYSTEM STILL ON TRACK FOR WEDNESDAY AND AGAIN RAISED POPS 10-20% ACROSS THE FORECAST AREA. WOULDN`T BE SURPRISED TO EVENTUALLY NEED LIKELY TO CATEGORICAL POPS FOR WIDESPREAD LIGHT SNOW. SNOW RATIOS WILL PROBABLY BE IN THE 16-19:1 RANGE GIVEN THE COLDER TEMPS. THE 500 MB LOW DROPS ALMOST STRAIGHT SOUTH ACROSS THE EASTERN DAKOTAS AND WESTERN MN DURING THE DAY ON WEDNESDAY. THE 30.12Z GUIDANCE SHIFTED THE TRACK WESTWARD FROM PREVIOUS RUNS. 700 MB LOW TRACK LOOKS GOOD FOR LIGHT SNOW ACROSS MUCH OF THE FORECAST AREA...SO UNLESS SOMETHING CHANGES OVER THE NEXT DAY...POPS SHOULD BE INCREASED. ALSO CARRYING ABOUT 0.5-1.0" OF SNOW IN THE FORECAST AT THIS POINT. && .AVIATION.../00Z TAF ISSUANCE/ STRATUS BEHIND COLD FRONT IS HEALTHIEST IN WESTERN MN...AND MORE SCATTERED FROM CENTRAL INTO NERN MN. SIGNIFICANT SURGE OF DRY AIR CONTINUES TO MOVE THROUGH NWRN MN. LATEST RAP DOES A GOOD JOB LATCHING ONTO THIS. BOTTOM LINE IS THAT EASTERN MN AND WESTERN WISC WILL BE IN AND OUT OF THE STRATUS THROUGH THE NIGHT. WESTERN MN SITES AXN/RWF ARE MORE LIKELY TO SEE PERSISTENT STRATUS FOR MOST OF THE NIGHT BUT EVEN THOSE LOCATIONS WILL SEE SOME POCKETS OF SCATTERED CLOUDS. MUCH DRIER AIR FROM NWRN MN SHOULD ARRIVE 10Z- 14Z FROM NORTHWEST TO SOUTHEAST...BRINGING SKC OR FEW CLOUDS. ONLY OTHER ISSUE WILL BE GUSTY WINDS REACHING 20 KNOTS AT TIMES BEFORE SETTLING DOWN AS SURFACE HIGH BUILDS IN LATE MONDAY AFTERNOON. KMSP...STRATUS IS QUITE PPATCHY AND KMSP WILL BE VARYING BETWEEN OVC AND SCT AT TIMES THROUGH AT LEAST 11Z AND MAYBE EVEN 14Z. SHOULD BE MOSTLY CLEAR THEREAFTER WITH INCOMING DRY AIR FROM NORTHWEST. NW WINDS WITH SOME GUSTS NEAR 20 KTS MONDAY MORNING WITH COLD ADVECTION. /OUTLOOK FOR KMSP/ TUE...VFR. SW WINDS 5-10 KNOTS. WED...MVFR CONDITIONS/-SN. SW WINDS 5-10 KNOTS BECOMING NW. THU...VFR. NW WINDS 5-10 KNOTS BECOMING W. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ CLF/TDK
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
952 PM EST TUE JAN 1 2013 .SYNOPSIS... A COLD FRONT WILL PUSH ACROSS THE AREA TONIGHT THEN STALL TO THE SOUTH WEDNESDAY. LOW PRESSURE WILL TRACK NORTHEAST ALONG THE FRONT WELL TO THE SOUTHEAST THURSDAY. HIGH PRESSURE WILL GRADUALLY BUILD OVER THE REGION FRIDAY THROUGH MONDAY. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... AS OF 945 PM TUESDAY...THE 00Z MHX SOUNDING STILL SHOWING SOME DRY AIR BETWEEN 800 AND 950 MB AND AS A RESULT ONLY VERY LIGHT PRECIPITATION IS BEING REPORTED OVER OUR NORTHERN CWA WITH JUST MID-LEVEL CLOUDS AND A FEW SPRINKLES OVER THE SOUTH. INDICATIONS FROM THE RAP AND NAM12 ARE THAT THE LOW-LEVEL WILL BECOME SATURATED BETWEEN NOW AND 06Z AND SHOULD SEE RAIN SHIELD EXPAND WITH THE INTENSITY OF RAIN PICKING UP THROUGH THE LATE NIGHT HOURS. ONLY MADE MINOR CHANGES TO THE CURRENT FORECAST. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... RAIN WILL BECOME MORE SPOTTY AND GRADUALLY END FROM NW TO SE AS MID LEVEL DRY AIR WORKS INTO THE AREA WED MORNING INTO THE EARLY AFTN. LOW CLOUDS WILL BE SLOW TO BREAK UP IN THE MOIST POST FRONTAL NE FLOW BUT SHUD SEE SOME SUN ESPECIALLY OVER NORTHERN AREAS DURING THE AFTN. LINGERING CLOUD COVER AND LOWERING THICKNESS VALUES YIELD HIGHS TOMORROW ONLY IN THE MID TO UPPER 40S NORTH TO LOW 50S SOUTH. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... AS OF 305 PM TUES...THE COLD FRONT THAT WILL HAVE STALLED WELL SOUTH OF THE AREA MAY INFLUENCE THE WEATHER FOR THUR...AS A WAVE OF LOW PRES DEVELOPS ALONG IT. HAVE MAINTAINED HIGH CHANCE POPS ALONG THE CRYSTAL COAST/SRN OBX...AND SLIGHT CHANCE FURTHER NORTH AND WEST. THE ECMWF/NAM/GEM GLOBAL ARE CONTINUING TO MAINTAIN RAIN SHIELD EXPANDING NORTH ACROSS THE CRYSTAL COAST...THOUGH GFS AND MAJORITY OF SREF MEMBERS KEEP THE WHOLE AREA DRY. BEST CHANCE OF SEEING RAIN WILL BE SOUTH OF A KENANSVILLE TO NEW BERN TO RODANTHE LINE. AREAS TO THE NORTH WILL JUST SEE CLOUDS AS DRY HIGH PRES AT THE SFC NOSES INTO THE COASTAL PLAIN/NORTHERN AREAS. DECENT GRADIENT IN PRECIP FROM THE COAST TO COASTAL PLAIN SO WILL LIKELY NEED TO FINE TUNE POPS AS PLACEMENT BECOMES MORE CERTAIN. TEMPS THURS WILL BE COOL AS WIDESPREAD RAIN AND LOW CLOUDS COUPLED WITH WEAK COLD- AIR DAMMING WILL PRODUCE HIGH TEMPS MID 40S INLAND WITH UPPER 40S COAST. WILL REMAIN BELOW MOS BLEND FOR TEMPS THURS DUE TO THE CLOUDS/PRECIP AND WEAK CAD. OPERATIONAL MODELS HAVE COME INTO BETTER AGREEMENT WITH FRONT OFF THE COAST PUSHING WELL OUT TO SEA SAT AND SURFACE RIDGE BUILDING EAST OVER THE REGION. COOL MORNING SAT MORNING AS VERY DRY HIGH PRES BUILDS IN WITH TD`S IN LOWER 20S AND CALM WINDS/CLEAR SKIES. BRIEF UPPER RIDGING SAT WILL BE REPLACED BY AN UPPER TROUGH DIGGING SE THROUGH THE OHIO RIVER VALLEY SUN INTO MON. SOME UNCERTAINTY AS TO WHETHER OR NOT SOUTHERN STREAM SHORTWAVE OVER TEXAS WILL MERGE WITH DIGGING UPPER TROUGH...OR WILL IT QUICKLY EJECT NE ALONG THE APPALACHIAN MOUNTAINS. BY SUN AFTERNOON EXTENDED GUIDANCE IN AGREEMENT WITH STRONG UPPER TROUGH PUSHING EAST ACROSS THE EAST COAST WITH COASTAL LOW DEVELOPMENT WELL OFF THE COAST WHICH PLACES EASTERN NC IN A MOSTLY DRY REGIME THROUGH MON. LATEST 01/12Z ECMWF IS A BIT WETTER FOR SUN...THOUGH HEIGHT FIELDS SEEM TO BE OUT OF PHASE WITH ITS ENSEMBLE MEAN SO WILL MAINTAIN DRY FCST ATTM. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... SHORT TERM /THROUGH 18Z WEDNESDAY/... AS OF 655 PM TUESDAY...LATEST LAMP GUIDANCE METEOGRAMS AND MODEL TIME SECTIONS SHOWS DEPTH OF MOISTURE INCREASING OVER THE NEXT 2 TO 4 HOURS AND WOULD EXPECT CEILINGS TO LOWER TO MVFR/IFR RANGE AS PRECIPITATION INCREASES IN COVERAGE AND COLD FRONT DROPS SOUTH WITH A MORE NORTHERLY SURFACE COMPONENT DEVELOPING. IFR CONDITIONS CONTINUE INTO LATE AFTERNOON WEDNESDAY WITH PERHAPS SOME MINOR IMPROVEMENT TO MVFR LATE. LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... AS OF 305 PM TUE...LOWER THAN AVG CONFIDENCE FOR THUR FORECAST...BUT OAJ/EWN COULD POSSIBLY SEE SUB VFR IN REDUCED CEILINGS WITH POSSIBLE RAIN DEVELOPING ...WHILE PGV/ISO SHOULD HAVE LOWER CHANCES OF RAIN AND VFR CIGS. HIGH PRESSURE BUILDS EAST OVER THE TERMINALS FRI THROUGH THE WEEKEND BRINGING A RETURN TO VFR AND DRY CONDITIONS WITH GENERALLY LIGHT WINDS. && .MARINE... SHORT TERM /THROUGH WEDNESDAY/... AS OF 10 PM TUESDAY...FRONTAL BOUNDARY CONTINUES ACROSS OUR NORTHERN WATERS WITH NW WINDS OVER THE ALBEMARLE SOUND AND NORTHERN WATERS BUT STILL W/WSWS ELSEWHERE. WINDS SHOULD GRADUALLY SHIFT TO MORE NORTH OVER THE NEXT 2 TO 3 HOURS OR SO. THE WINDS WILL GRADUALLY INCREASE TO 15 TO 20 KTS BY WED AFTN. WAVEWATCH BUILDS SEAS TO 5 FT LATE WED. MAY SEE A BRIEF PERIOD OF SMALL CRAFT ADVISORY CONDITIONS WED AFTN BUT WILL NOT ISSUE SCA ATTM GIVEN THE EXPECTED SHORT DURATION AND MARGINAL PARAMETERS. LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... AS OF 305 PM TUE...WINDS AOB 15 KNOTS THURS AS NE SURGE ABATES. BETTER AGREEMENT BETWEEN MEDIUM RANGE MODELS WITH COASTAL LOW DEVELOPMENT THURS WELL OFFSHORE. KEPT CONTINUITY AND MANUALLY ADJUSTED SEAS FORECAST TO REFLECT FORECAST WINDS WHICH YIELDS SEAS AOB 5 FEET THROUGH THE EXTENDED WITH CONTINUED MEDIUM CONFIDENCE. MODERATE CAA ON FRI WITH NW FLOW AND HAVE CONTINUED NEAR SCA WINDS...WITH SEAS BUILDING 5 FEET OR HIGHER. HIGH PRES MOVES SOUTH OF THE WATERS LATE FRI THROUGH EARLY SAT WITH WINDS AND SEAS ABATING. RETURN SW FLOW INC WITH THE DEPARTING HIGH LATE SAT THROUGH EARLY SUN AS APPROACHING TROUGH INC THE GRADIENT WITH WINDS AGAIN AOA 15 KT. FRONT AND TROUGH WILL PASS THROUGH ON SUN WITH WINDS TURNING NW AND REMAINING ABOVE 15 KT WITH MODERATE CAA. MAY NEED TO INC WINDS JUST A BIT ON SUN IF COLD AIR SURGE IS MORE SIG THAN EXPECTED. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...NONE. && $$ SYNOPSIS...BTC/RF NEAR TERM...CTC SHORT TERM...BTC/RF LONG TERM...DAG/TL AVIATION...CTC/BTC/TL MARINE...CTC/BTC/TL
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
715 PM CST TUE JAN 1 2013 .DISCUSSION...A COUPLE MINOR UPDATES NEEDED TO THE FORECAST TONIGHT. THE LIGHT SNOW ENTERING THE NE FA IS ABOUT 3 HOURS AHEAD OF SCHEDULE...AND WILL UPDATE POPS ACCORDINGLY (MUCH LIKE THE NAM12 AND REGIONAL GEM). LOW CLOUDS ARE HANGING TOUGH ACROSS THE SOUTHERN VALLEY AND MINNESOTA AREAS. 23Z RAP INDICATES THESE LOWER CLOUDS WILL REMAIN UNTIL WINDS SWITCH TO THE WEST...AFTER 07Z-09Z. THEN...MVFR CIGS WILL QUICKLY MOVE IN BEHIND THE WIND SWITCH. WILL NEED TO INCREASE MIN TEMPS ACROSS THESE AREAS AS A RESULT (LIKELY NOT MUCH ADDITIONAL DROP). && .AVIATION...IFR CIGS ARE HANGING TOUGH ACROSS THE SOUTHERN RED RIVER VALLEY AND INTO MINNESOTA. HIGH RESOLUTION MODELS INDICATE THESE CIGS REMAINING THROUGH MUCH OF THE NIGHT...UNTIL SURFACE WINDS BECOME WEST (07Z-09Z). BEHIND THE WIND SHIFT TO THE WEST...MVFR CLOUDS WILL MOVE EAST AND BRING SOME LIGHT SNOW. THIS WILL RESULT IN LOWER VSBYS. && .PREV DISCUSSION... /ISSUED 318 PM CST TUE JAN 1 2013/ SHORT TERM... FCST IN GOOD SHAPE. TEMPS MAIN ISSUE AS LOOK FOR RISING TEMPS TONIGHT THEN A FALL WED AFTN. THUS USED A BLEND OF SREF DIURNAL MODEL TOOL AND CONSALL/GFS MOS TO CREATE HOURLY TEMP CURVE. WATER VAPOR SHOWS TIGHT SPIN WITH UPPER LEVEL SHORT WAVE IN CNTRL SASK NEAR PRINCE ALBERT-SASKATOON. SFC LOW A BIT FARTHER NORTH AND EAST. QUITE A BIT OF MILD AIR SOUTH AND WEST OF UPPER LOW WITH LOW 30S IN CNTRL SASK INTO EAST CENTRAL ALBERTA. THE VORT WILL DROP SOUTHEAST THRU ERN ND 12Z-18Z WED. SFC LOW WILL DROP SOUTHEAST TOWARD LAKE OF THE WOODS REGION DURING THE SAME PERIOD. MID LEVEL FORCING ALONG 850 MB WARM ADV ZONE CREATING A BAND OF LIGHT SNOW MOVING INTO SW MANITOBA...THRU SE SASK INTO NW ND/ERN MT AT MID AFTERNOON. MODELS DO HAVE THIS CONTINUING TO PUSH SOUTHEAST TONIGHT BUT WEAKENING A BIT. BUT STILL ENOUGH FOR A PERIOD OF LIGHT SNOW SO WENT LIKELY POPS FOR THIS BAND STARTING IN DVL BASIN EARLY EVE AND THEN SPREADING EAST INTO NW-WCNTRL MN BY 12Z (KEPT CHC POPS FAR EAST ALONG DLH AND MPX CWA BORDERS). ONCE THIS BAND MOVES THRU QUIET AND THEN SOME LIGHT SNOWS WILL DROP SOUTHEAST WITH THE UPPER WAVE THRU THE DAY WED ENDING IN THE SOUTHEASTERN FCST AREA WED EVE. ACCUMS FOR THE EVENT REMAIN LIGHT HALF INCH TO INCH AND A HALF. IT WILL TURN BREEZY WEDNESDAY WITH NORTHWEST WINDS 15 TO 25 MPH. TEMPS WILL WARM TONIGHT AS WINDS TURN MORE WESTERLY AS LOW MOVES NORTHEAST OF OUR AREA SO DO EXPECT A WARM UP WITH WARMEST AIRMASS SPREAD THRU ERN ND INTO THE RED RIVER VALLEY AFTER 06Z AND MORE TOWARDS 12Z WED AS TEMPS SHOULD RISE INTO THE UPPER TEENS AND LOWER 20S. COLDER AIR DROP IN WED AFTN FROM THE NORTHWEST. MOST OF WED TO BE MILD THOUGH WITH MID OR UPPER 20S SOUTH HALF OF THE FCST AREA. CLEARING WILL MOVE IN WED OVERNIGHT INTO THURSDAY AS HIGH MOVES IN WITH ONLY WEAK COLD ADVECTION AND COOLER AIR. WARMER AIR WILL MOVE IN FRIDAY AS WINDS TURN SOUTHWEST TO WEST AHEAD OF NEXT SHORT WAVE. LONG TERM (FRI NIGHT-TUE)... WILL START OUT THE LONG TERM IN NORTHWEST FLOW ALOFT WITH A WEAK WAVE MOVING THRU. ECMWF IS A BIT SLOWER WITH THIS FEATURE THAN THE GFS BUT AT THIS POINT ONLY THE GFS GENERATES ANY VERY LIGHT PCPN WITH IT. SINCE FORECAST CONTINUITY IS DRY AND GUIDANCE IS ALSO STAYING DRY WILL NOT DEVIATE. AFTER THIS WAVE MOVES EAST RIDGING TRIES TO BUILD IN ALTHOUGH IT DOES APPEAR TO FLATTEN AS IT COMES THRU. THIS WILL BRING IN VERY MILD AIR WITH HIGHS GENERALLY RUNNING ABOVE NORMAL FOR SUN/MON/TUE. MAY BE ANOTHER CHANCE FOR LIGHT SNOW ON TUE ALTHOUGH MODELS ARE NOT IN VERY GOOD AGREEMENT THIS FAR OUT. FORECAST HAD SOME LIGHT SNOW MENTIONED SO WILL KEEP. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG
AREA FORECAST DISCUSSION
NWS BISMARCK ND
143 AM CST MON DEC 31 2012 .DISCUSSION... CLOUDS CONTINUE TO DIMINISH ASYMMETRICALLY SO CHALLENGES IN GETTING TEMPERATURES RIGHT TONIGHT. LATEST HRRR SEEMS TO HAVE A GOOD HANDLE ON THE CURRENT SITUATION SO LEANED IN ITS DIRECTION. GRADUAL CLEARING AREA MOVING SOUTH ACROSS CENTRAL ND...WITH CLOUDS PERSISTING WEST NEAR A SFC BOUNDARY. WHERE CLOUDS CLEAR TEMPERATURES DROP SIGNIFICANTLY. ISOLD FLURRIES ACCOMPANYING THE CLOUDS WEST AND SOUTH. ADJUSTED OVERNIGHT LOWS UP SIGNIFICANTLY SOUTH AND LOWERED NORTH CENTRAL AND NORTHEAST THROUGH 15Z. WIND CHILL HEADLINES ON TRACK. && .AVIATION...AT 1 AM CST...SURFACE HIGH PRESSURE CONTINUED TO BUILD INTO NORTHERN NORTH DAKOTA. THE SURFACE HIGH WILL SQUEEZE THE MVFR TO LOCALLY IFR CONDITIONS INTO WESTERN NORTH DAKOTA (KISN-KDIK) INTO MONDAY MORNING. MVFR BECOMING VFR AT KBIS-KJMS LATE SUNDAY NIGHT INTO MONDAY MORNING AS THE HIGH BUILDS SOUTH. VFR AT KMOT. THEN THE BAND OF MVFR STRATUS WILL MOVE EAST INTO CENTRAL NORTH DAKOTA KMOT-KBIS AFTER 18-20Z. && .BIS WATCHES/WARNINGS/ADVISORIES... WIND CHILL ADVISORY UNTIL 9 AM CST THIS MORNING FOR NDZ002>005- 010>013-022-023-025-037-048-051. && $$ UPDATE...NH AVIATION...WAA
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
431 AM MST MON DEC 31 2012 .AVIATION...12Z TAFS AN AREA OF STRATUS WITH MVFR/IFR CIGS WILL CONTINUE TO ADVECT ACROSS PARTS OF WESTERN AND CENTRAL SOUTH DAKOTA. CONDITIONS ON THE WHOLE WILL IMPROVE THROUGH THIS AFTERNOON. PESKY STATUS IN THE LEE OF THE BH REMAINS ERODED INVOF KRAP BY BH DOWNSLOPING. RETAINED SCT IFR CIGS THERE FOR NOW UNTIL A BETTER HANDLE ON DOWNSLOPE TRENDS ARE ESTABLISHED. LATEST RAP AND NAM GUIDANCE SUGGEST A POSSIBLE INFLUX OF LOWER CIGS LATER THIS MORNING AND INTO THE AFTERNOON WITH A DEEPENING SE WIND. HOWEVER...DIURNAL HEATING AND CONTINUED WESTERLY FLOW AT H7 AND ABOVE SUGGEST VFR CONDITIONS MAY PREVAIL. WILL MONITOR ATTM. && .PREV DISCUSSION... /ISSUED 311 AM MST MON DEC 31 2012/ DISCUSSION...CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER SOUTHWESTERN ONTARIO...WITH A COLD FRONT STRETCHING ACROSS MN...NORTHERN SD...AND INTO EASTERN MT. HIGH PRESSURE IS LOCATED TO THE NORTH OVER THE CANADIAN PRAIRIE PROVS. LOW PRESSURE IS ALSO DEVELOPING TO THE SOUTH OF THE REGION ACROSS THE SOUTHERN ROCKIES. UPPER LEVEL ANALYSIS CONTINUES TO SHOW LOW OVER THE HUDSON BAY REGION...WITH NORTHWESTERLY FLOW OVER OUR REGION. TROF OVER THE SOUTHWESTERN CONUS IS NOW MOVING EASTWARD INTO THE SOUTHERN ROCKIES AND PLAINS. SAT PICS ARE SHOWING EXTENSIVE AREA OF STRATUS STRETCHING FROM EASTERN MT INTO MUCH OF THE DAKOTAS. THE COVERAGE OF THE STRATUS IS MORE SPOTTY OVER WESTERN SD...BUT WILL LIKELY FILL IN A BIT MORE EARLY THIS MORNING AND LINGER THROUGH A GOOD PORTION OF THE DAY...ESPECIALLY FOR AREAS EAST OF THE BLACK HILLS INTO CENTRAL SD. TEMPS CURRENTLY RANGE FROM THE SINGLE DIGITS AND LOWER TEENS OVER MOSTLY CLEAR AREAS...TO THE TEENS AND LOWER 20S WHERE CLOUD COVER IS IN PLACE. WINDS ARE LIGHT AND VARIABLE OVER MOST OF THE AREA. A SOMEWHAT UNSETTLED AND CONTINUED COLD PATTERN CAN BE EXPECTED THROUGH WEDNESDAY AS A SERIES OF UPPER LEVEL DISTURBANCES PASS THROUGH THE AREA IN NORTHWESTERLY FLOW. MOISTURE WITH THESE SYSTEMS WILL BE RATHER LIMITED...BUT IT IS LOOKING LIKE SOME LIGHT ACCUMULATIONS OF SNOW WILL BE LIKELY ACROSS PORTIONS OF THE AREA TUESDAY NIGHT AND WEDNESDAY...ESPECIALLY NORTHEASTERN WY AND THE NORTHERN BLACK HILLS. FOR TODAY...AREAS OF LOW CLOUDS WILL PERSIST ACROSS THE AREA... MAINLY TO THE NORTH AND EAST OF THE BLACK HILLS. COVERAGE SHOULD DISSIPATE SOME BY THE MIDDAY AND AFTERNOON HOURS. WILL ALSO INCLUDE A FEW FLURRIES IN THE FORECAST FOR NORTHWESTERN SD INTO POSSIBLY FAR NORTHEASTERN WY. TEMPS WILL BE ON THE COLD SIDE AS FRONT SKIRTS THE AREA. HIGHS WILL BE IN THE MID TEENS TO MID 20S...COLDEST OVER NORTHEASTERN PORTIONS OF THE CWA. ANOTHER DISTURBANCE WILL SLIDE SOUTHWARD FROM CANADA THIS AFTERNOON AND TONIGHT. MOISTURE WILL AGAIN BE VERY LIMITED WITH THIS WAVE...BUT WILL GO AHEAD AND ADD SOME FLURRIES TO THE FORECAST FOR TONIGHT... MAINLY FOR THE HIGHER ELEVATIONS OF NORTHEASTERN WY AND THE BLACK HILLS. NEW YEARS DAY WILL START OFF WITH SOME SUNSHINE...THEN INCREASING CLOUDS IN THE AFTERNOON FROM THE NORTH AS THE NEXT WAVE APPROACHES. THIS ONE LOOKS LIKE IT WILL HAVE MORE MOISTURE TO WORK WITH AS IT SLIDES THROUGH TUESDAY NIGHT. THE BETTER MOISTURE AND LIFT WILL PASS THROUGH NORTHEASTERN WY AND FAR WESTERN SD WITH THIS WAVE. HAVE RAISED POPS OVER WESTERN PORTIONS OF THE CWA...WITH LIKELY POPS OVER NORTHEASTERN WY AND THE NORTHERN BLACK HILLS AREA. COULD SEE AN INCH OR TWO OF SNOW ACROSS PORTIONS OF NORTHEASTERN WY AND THE NORTHERN HILLS OVERNIGHT. HIGHS ON TUESDAY WILL BE IN THE 20S...WITH LOWS TUESDAY NIGHT IN THE SINGLE DIGITS AND TEENS. AS THIS WAVE PASSES SOUTH BY EARLY WEDNESDAY...ANOTHER ONE WILL SLIDE SOUTH THROUGH THE NORTHERN PLAINS WEDNESDAY INTO WEDNESDAY NIGHT. ASSOCIATED COLD FRONT WILL ALSO PASS THROUGH THE AREA WEDNESDAY MORNING. MODELS DIFFER SOME ON THE TRACK AND STRENGTH OF THIS ONE...BUT THE BRUNT OF IT WILL PASS EAST OF THE FORECAST AREA. THERE WILL STILL BE ENOUGH LIFT AND MOISTURE TO THE WEST OF IT TO BRING SNOW SHOWERS. WINDS WILL BE RATHER GUSTY BY LATE WEDNESDAY MORNING ACROSS THE SD PLAINS AS FRONT PASSES AND PRESSURE GRADIENT TIGHTENS. WILL LIKELY SEE SOME BLOWING SNOW WHERE SNOW DOES FALL. THIS SYSTEM COULD BRING AN INCH OR SO OF SNOW TO SOME AREAS AS IT PASSES...MAINLY OVER WESTERN SD. UPSLOPE ENHANCED SNOWFALL OVER THE NORTHERN HILLS COULD BRING A FEW INCHES TO FAVORED AREAS. HIGHS WILL GENERALLY BE IN THE 20S. EXTENDED...A TRANSITION TO WARMER NW PAC ORIGIN FLOW WILL OCCUR IN THE LONG TERM PERIOD AS A MASSIVE WESTERN NOAM RIDGE ADVECTS/PROPAGATES EAST IN THE PERIOD. THE MAIN FOCUS IN THE PERIOD WILL BE AN EXPANDING EAST ASIAN UPPER JET THAT WILL SUPPORT AN EASTWARD SHIFT OF LOWER HEIGHTS...AND DOWNSTREAM ANTECEDENT RIDGING. FORECAST MODELS REMAIN WARM PER A PAC DOWNSLOPE MODIFIED AIRMASS EXPECTED INTO THE REGION BY LATER THUR AT THE EARLIEST. BOTH THE GEM AND THE GFS PROG H85 T/S IN THE 5-8 C RANGE...WHICH IF MIXED WOULD SUPPORT HIGHS WELL INTO THE 40S /AND POSSIBLY LOWER 50S IN THE LEE OF THE BH/...ESP IF TIMING OF THE THERMAL RIDGE LINES UP WITH DAYTIME HEATING. EVEN GIVEN THE RUN TO RUN CONTINUITY...STILL DID NOT JUMP ON A SOLUTION THAT WARM THIS FAR OUT /ESP GIVEN CONCERNS ON SNOW PACK/...BUT CONTINUE TO BIAS TEMPS UP IN THE FRI-SUN PERIOD...ESP OVER THE HIGHER TERRAIN. ONE KEY AND NOTICEABLE DIFFERENCE AMONG FORECAST MODELS IS THE HANDLING OF A NW CONUS CLOSED UPPER LOW TOWARD THE END OF THE WEEK...WHICH EXPLAINS SOME MINOR THERMAL AND HEIGHT DIFFERENCES TOWARD NEXT WEEKEND. THE 00Z ECMWF RETAINS A CLOSED LOW OVER THE PAC NW THROUGH FRI WITH MUCH SLOWER EASTWARD PROGRESSION OF THIS FEATURE...WHILE THE GFS AND GEM EJECT THIS SYSTEM EAST 1-1/2 DAYS EARLIER. THE ECMWF SOLUTION HAS SOME SUPPORT FROM GEFS MEMBERS. HOWEVER...MEAN GEFS SOLUTIONS ARE LEANING TOWARD THE GEM/GFS SOLUTION OF A RIDGE SQUASHING WAVE FRI...WHICH COULD SUPPORT A SMALL CHANCE FOR LIGHT SNOW AND SLIGHTLY COOLER TEMPS ACROSS THE NORTHERN ZONES FRI. HENCE...HAVE REMAINED CONSERVATIVE PER SIG TRENDING TOO FAR FROM CONSENSUS AND PREVIOUS FORECAST NUMBERS...ESP IN THIS PERIOD. OTHERWISE...DRY NW FLOW WILL PREVAIL THROUGH THE REMAINDER OF THE PERIOD...WITH MUCH MILDER CONDITIONS EXPECTED TO CONTINUE INTO THE FOLLOWING WEEK PER ZONAL FLOW...GIVEN STRONG INDICATIONS FOR REMOVAL OF THE NORTH ATLANTIC BLOCK. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ SHORT TERM...26 EXTENDED...JC AVIATION...JC
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1056 AM CST MON DEC 31 2012 .UPDATE... A GLOOMY DAY CONTINUES ACROSS THE REGION THIS MORNING. WIDESPREAD FOG CONTINUES WITH VISIBILITIES OCCASIONALLY BELOW A MILE...MAINLY SOUTH OF INTERSTATE 20. MOST OF THE RAIN IS NOW EAST OF A LINE FROM GAINESVILLE TO GRANBURY TO LAMPASAS...HOWEVER...A FEW AREAS OF DRIZZLE ARE OCCURRING WEST OF THIS LINE ALONG WITH THE FOG. THE RAIN WILL CONTINUE TO SLOWLY PROGRESS EAST TODAY WITH HIGHEST RAIN CHANCES OVER THE NORTHEAST AND EASTERN COUNTIES. THE RAIN WILL LIKELY COME TO AN END OVER ALL BUT THE SOUTHEASTERN THIRD OF THE REGION BY SUNSET. A DRYLINE/WARM FRONT WILL PUNCH INTO THE WESTERN ZONES THIS AFTERNOON...CLEARING OUT THE CLOUDS AND ALLOWING TEMPS TO WARM INTO THE UPPER 50S. IN ADDITION...A WARM FRONT WILL MOVE NORTH INTO OUR FAR SOUTH AND SOUTHEASTERN COUNTIES...WARMING TEMPS THERE INTO THE MID AND UPPER 50S. IT IS POSSIBLE THAT SOME 60 DEGREE TEMPS WILL BE REACHED IN EITHER OF THESE TWO PLACES...BUT THE ARRIVAL OF BOTH FEATURES WILL BE LATER IN THE DAY. UNTIL THEN...CLOUDY SKIES AND THE RAIN AND FOG WILL KEEP TEMPERATURES COOL WITHOUT MUCH CHANGE THROUGHOUT THE DAY. NEAR THE WARM FRONT LATER THIS AFTERNOON...SOME WEAK ELEVATED INSTABILITY IS PRESENT ON AREA SOUNDINGS AND HAVE OPTED TO LEAVE THE ISOLATED THUNDER MENTION IN THE FAR SOUTHEASTERN COUNTIES AFTER 00Z/6 PM CST. WITH THE FREEZING LEVEL UP AROUND 11-12 KFT...WILL REMOVE THE MENTION OF HAIL FROM THE HWO. 82/JLD && .AVIATION... AMENDED TAFS TO SHOW DECREASING VISIBILITIES AND CEILINGS AS WARM FRONT APPROACHES FROM THE SOUTHWEST. DONT THINK THE WARM FRONT WILL MOVE THROUGH TAF SITES AND THEREFORE HAVE KEPT WINDS S/SE THROUGH THIS EVENING. RUC FORECAST OF CIGS NEAR 200-500 FEET LOOK REASONABLE AND VSBY SHOULD DROP BELOW 2 MILES. IT IS UNCLEAR HOW MUCH IMPROVEMENT THERE WILL BE LATER THIS AFTERNOON BUT AS WINDS GO WESTERLY JUST ABOVE THE SURFACE THIS MAY ALLOW VSBY TO IMPROVE. RAIN SHOULD END AROUND 18-19Z. WILL CONTINUE TO MONITOR TRENDS. TR.92 .../PREVIOUS AVIATION DISCUSSION/... CIGS AND VSBYS HAVE DECREASED DURING THE PAST FEW HOURS DUE TO THE LIGHT RAIN SPREADING EAST TO THE I-35 CORRIDOR. THIS TREND SHOULD CONTINUE...AND TAFS WILL LIKELY BE INITIALIZED WITH IFR CIGS WHICH SHOULD PERSIST THROUGH MUCH OF THE DAY. MEANWHILE A COASTAL TROUGH WILL TRY TO LIFT NORTH LATER TODAY AS A WARM FRONT... BUT SHOULD REMAIN SOUTH OF TAF LOCATIONS. ISENTROPIC ASCENT WILL CONTINUE NORTH OF THE BOUNDARY...FURTHER SATURATING THE LOWER ATMOSPHERE AND LIKELY ADDING FOG TO THE MIX. EXPECT GENERALLY 1-3SM VISIBILITIES WITH CIGS LOWERING TO NEAR 005 AT ALL LOCATIONS BY MIDDAY. INITIAL SHORTWAVE WILL EJECT NORTHEAST OF THE REGION THIS EVENING ALLOWING A WEAK COLD FRONT TO EASE SOUTH OF THE TERMINALS. THIS MAY ALLOW CONDITIONS TO IMPROVE BRIEFLY AROUND SUNSET...BUT THE SHALLOW NATURE OF THE COOL AIRMASS AND QUICK RETURN OF ISENTROPIC LIFT MAY CAUSE FOG FORMATION AND REDUCED VISIBILITIES AGAIN BY 06Z. FORTUNATELY THE LATEST MOS GUIDANCE HAS BACKED OFF THE SEVERITY OF THE CONDITIONS TONIGHT SO IT LOOKS LIKE FOG MAY BE SHORT LIVED DURING THE OVERNIGHT HOURS. A SECOND SHORTWAVE WILL THEN TRANSLATE THE AREA TUESDAY MORNING...WHICH SHOULD CREATE A STRONGER PUSH OF DRIER AIR AND IMPROVING CONDITIONS AFTER 12Z TUESDAY. 30 && .PREV UPDATE... .UPDATE... WE HAVE NOTICED A FEW MITIGATING ITEMS THAT IS KEEPING RAIN FROM BEING MORE THAN JUST VERY LIGHT RAIN OR DRIZZLE. ONE REASON IS THE DRY LAYER NOTED ON THE 12Z FWD SOUNDING BETWEEN 850-650MB...MEANING THE COLUMN IS SHALLOW AND NOT DEEPLY SATURATED. SECOND...THE DRY SLOT ASSOCIATED WITH THE UPPER JET MAX ROUNDING THE BASE OF THE FOUR CORNERS UPPER TROUGH IS NOW PUNCHING NORTHEAST UP THROUGH WESTERN TEXAS AND MOVING EAST FASTER THAN EXPECTED. WITH THESE TRENDS IN MIND...HAVE UPDATED MORNING FORECAST TO LOWER POPS IN THE WESTERN THIRD OF NORTH TEXAS INTO THE CHANCE CATEGORY... GOING TO SLIGHT CHANCE IN THE AFTERNOON. TOO MUCH UNCERTAINTY ON THE AFTERNOON PERIOD AND WILL MAINTAIN ONGOING FORECAST. RAIN AMOUNTS WILL BE LIGHT WITH AREAS OF FOG EXPECTED THROUGH MUCH OF THE DAY. THE APPROACHING UPPER TROUGH WILL LIKELY STEEPEN LAPSE RATES ACROSS CENTRAL/SOUTHEAST TEXAS NEAR FRONTAL WAVE TO OUR SOUTH. WILL MAINTAIN ISOLATED THUNDERSTORM MENTION ACROSS THESE AREAS. 05/ && .PREV DISCUSSION... /ISSUED 300 AM CST MON DEC 31 2012/ A WET AND COOL FORECAST IS EXPECTED TODAY INTO THIS EVENING...AS DEEP LONGWAVE TROUGH OVER THE GREAT BASIN/FOUR CORNERS REGION CONTINUES MOVING PROGRESSIVELY EAST TOWARD THE SOUTHERN PLAINS THE NEXT 24-36 HOURS. ISENTROPIC ASCENT AND WAA OVER THE TOP OF THE FRONTAL INVERSION ANCHORED AROUND 800MB HAS ALREADY BEGUN IN ERNEST ACROSS THE SOUTH PLAINS INTO WESTERN NORTH TX EARLY THIS MORNING WITH WIDESPREAD AREAS OF LIGHT RAIN OCCURRING ACROSS THESE AREAS. THE RAIN SHIELD WILL SPREAD GRADUALLY EAST ACROSS NORTH TEXAS THROUGH THE DAY WITH THE BEST SATURATION AND UPGLIDE OCCURRING ACROSS THE NORTHEAST HALF OF THE CWA WHERE RAINFALL UPWARDS TO ONE INCH OR SLIGHTLY MORE ARE NOT OUT OF THE QUESTION WITH LESSER AMOUNTS FURTHER SOUTH. ALSO WITH LOW LEVEL COLD AIR IN PLACE...THE INCREASING LIGHT TO OCCASIONALLY MODERATE RAINFALL WILL HELP BOTH VISIBILITIES AND CEILINGS FALL AFTER DAYBREAK AND THROUGHOUT MOST OF THE DAY. EXPECT THE MOST WIDESPREAD FOG AND RAIN TO OCCUR ACROSS THE NORTHERN COUNTIES...AND MORE PATCHY ACROSS THE SOUTH AND WEST WITHIN THE WARMER TEMPERATURES NEAR THE WARM FRONT. EITHER WAY...CONDITIONS WILL BE SLOPPY INTO THE EVENING HOURS. ANOTHER CHALLENGE TODAY IS HIGH TEMPERATURES...AS A FRONTAL WAVE DEVELOPS ACROSS SOUTH-CENTRAL TEXAS AND MOVES UP THROUGH THE UPPER TEXAS COAST DURING THE EVENING HOURS. MODELS HAVE DIFFERENT PERSPECTIVES ON HOW FAR NORTH THE WARM FRONT WILL MOVE INTO OUR CENTRAL TEXAS AND SOUTHEAST COUNTIES. HAVE DECIDED TO LEAN WITH A COMPROMISE AT THIS POINT AS IT IS ANYONE/S GUESS ON THIS EVOLUTION AND KEEP HIGHS IN THE 40S NORTH OF I-20...TO 55-60 IN OUR CENTRAL TEXAS AND FAR SOUTHWEST COUNTIES. LAPSE RATES WILL STEEPEN WITHIN THE NORTHWEST EDGE OF THE WARM NOSE AHEAD OF THE SYSTEM AND NEAR THE WARM FRONT ACROSS OUR SOUTHERN COUNTIES THIS AFTERNOON AND EVENING. WITH UNCERTAINTIES REGARDING WHERE THE WARM FRONT WILL RESIDE...HAVE ONLY ADDED ISOLATED THUNDERSTORMS TO AREAS SOUTHEAST OF A KILLEEN-ATHENS LINE THIS AFTERNOON/EVENING. DO NOT EXPECT SEVERE STORMS...BUT A STRONG STORM OR TWO WITH HAIL IS POSSIBLE WITH LOW FREEZING LEVELS IN PLACE. THERE COULD BE A BRIEF 3-6 HOUR WINDOW FOR SURFACE-BASED ACTIVITY IN MILAM/ROBERTSON/LEON/ANDERSON COUNTIES WHERE GUSTY WINDS COULD BE A THREAT AS WELL. MEANWHILE TONIGHT...A COLD FRONT CURRENTLY OVER THE CENTRAL HIGH PLAINS WILL ARRIVE ACROSS THE RED RIVER BY MID-LATE EVENING...THEN SURGE SLOWLY THROUGH NEW YEARS MORNING. LOOK FOR AREAS OF FOG TO CONTINUE AHEAD OF THE FRONT DURING THE EVENING HOURS WITH LIGHTER WINDS AND WARMER TEMPERATURES. IT APPEARS ANY CHANCES FOR WINTER PRECIPITATION WILL BE SHUT DOWN ACROSS OUR AREA WITH A DRIER AIRMASS ARRIVING AND WESTERLY FLOW PROVIDING ISENTROPIC DOWNGLIDE WITHIN THE LOWER LEVELS. A FEW SHOWERS WILL PERSIST ACROSS THE SOUTHEAST COUNTIES THROUGH TUESDAY MORNING. A DRY AND COLD PERIOD WILL OCCUR NEW YEARS DAY AND THROUGH THE MIDDLE PART OF THE WEEK...AS A PERSISTENT TROUGH CONTINUES ACROSS THE CENTRAL CONUS AND HELPS REINFORCE THE CHILLY AIRMASS IN PLACE WITH ADDITIONAL POLAR SURGES. HAVE GONE BELOW MOS VALUES ON HIGH TEMPERATURES WITH LITTLE IN THE WAY OF WAA OR RETURN FLOW OCCURRING THROUGH THURSDAY. MID LEVEL ENERGY DOES DEEPEN ACROSS THE OKLAHOMA INTO THE OZARKS ON THURSDAY AND HAVE HELD SLIGHT CHANCES FOR A COOL RAIN WELL SOUTH OF I-20 WHERE WEAK ISENTROPIC ASCENT MAY OCCUR...BUT CONFIDENCE IS NOT HIGH AT THIS TIME WITH MODEL DIFFERENCES ON POSITION AND STRENGTH OF THIS SHORTWAVE DROPPING SOUTH. OTHERWISE...A GRADUAL MODIFICATION ON TEMPS AND DRY CONDITIONS ARE EXPECTED FRIDAY INTO NEXT WEEKEND...THOUGH AGAIN MODEL AGREEMENT IS POOR ON OVERALL PATTERNS BOTH ALOFT AND AT THE SURFACE. 05/ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 46 38 45 29 41 / 90 10 10 5 10 WACO, TX 53 43 48 30 44 / 70 20 20 5 10 PARIS, TX 43 37 45 26 40 / 100 30 10 10 10 DENTON, TX 45 35 41 25 40 / 80 10 10 5 10 MCKINNEY, TX 45 37 43 25 40 / 100 10 10 5 10 DALLAS, TX 46 39 45 31 41 / 100 10 10 5 10 TERRELL, TX 48 40 46 28 41 / 100 20 10 10 10 CORSICANA, TX 52 43 48 32 42 / 90 40 20 10 10 TEMPLE, TX 56 44 49 31 45 / 60 30 20 5 10 MINERAL WELLS, TX 51 35 43 25 42 / 10 10 10 5 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 92/82
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
940 AM CST MON DEC 31 2012 .AVIATION... AMENDED TAFS TO SHOW DECREASING VISIBILITIES AND CEILINGS AS WARM FRONT APPROACHES FROM THE SOUTHWEST. DONT THINK THE WARM FRONT WILL MOVE THROUGH TAF SITES AND THEREFORE HAVE KEPT WINDS S/SE THROUGH THIS EVENING. RUC FORECAST OF CIGS NEAR 200-500 FEET LOOK REASONABLE AND VSBY SHOULD DROP BELOW 2 MILES. IT IS UNCLEAR HOW MUCH IMPROVEMENT THERE WILL BE LATER THIS AFTERNOON BUT AS WINDS GO WESTERLY JUST ABOVE THE SURFACE THIS MAY ALLOW VSBY TO IMPROVE. RAIN SHOULD END AROUND 18-19Z. WILL CONTINUE TO MONITOR TRENDS. TR.92 .../PREVIOUS AVIATION DISCUSSION/... CIGS AND VSBYS HAVE DECREASED DURING THE PAST FEW HOURS DUE TO THE LIGHT RAIN SPREADING EAST TO THE I-35 CORRIDOR. THIS TREND SHOULD CONTINUE...AND TAFS WILL LIKELY BE INITIALIZED WITH IFR CIGS WHICH SHOULD PERSIST THROUGH MUCH OF THE DAY. MEANWHILE A COASTAL TROUGH WILL TRY TO LIFT NORTH LATER TODAY AS A WARM FRONT... BUT SHOULD REMAIN SOUTH OF TAF LOCATIONS. ISENTROPIC ASCENT WILL CONTINUE NORTH OF THE BOUNDARY...FURTHER SATURATING THE LOWER ATMOSPHERE AND LIKELY ADDING FOG TO THE MIX. EXPECT GENERALLY 1-3SM VISIBILITIES WITH CIGS LOWERING TO NEAR 005 AT ALL LOCATIONS BY MIDDAY. INITIAL SHORTWAVE WILL EJECT NORTHEAST OF THE REGION THIS EVENING ALLOWING A WEAK COLD FRONT TO EASE SOUTH OF THE TERMINALS. THIS MAY ALLOW CONDITIONS TO IMPROVE BRIEFLY AROUND SUNSET...BUT THE SHALLOW NATURE OF THE COOL AIRMASS AND QUICK RETURN OF ISENTROPIC LIFT MAY CAUSE FOG FORMATION AND REDUCED VISIBILITIES AGAIN BY 06Z. FORTUNATELY THE LATEST MOS GUIDANCE HAS BACKED OFF THE SEVERITY OF THE CONDITIONS TONIGHT SO IT LOOKS LIKE FOG MAY BE SHORT LIVED DURING THE OVERNIGHT HOURS. A SECOND SHORTWAVE WILL THEN TRANSLATE THE AREA TUESDAY MORNING...WHICH SHOULD CREATE A STRONGER PUSH OF DRIER AIR AND IMPROVING CONDITIONS AFTER 12Z TUESDAY. 30 && .UPDATE... WE HAVE NOTICED A FEW MITIGATING ITEMS THAT IS KEEPING RAIN FROM BEING MORE THAN JUST VERY LIGHT RAIN OR DRIZZLE. ONE REASON IS THE DRY LAYER NOTED ON THE 12Z FWD SOUNDING BETWEEN 850-650MB...MEANING THE COLUMN IS SHALLOW AND NOT DEEPLY SATURATED. SECOND...THE DRY SLOT ASSOCIATED WITH THE UPPER JET MAX ROUNDING THE BASE OF THE FOUR CORNERS UPPER TROUGH IS NOW PUNCHING NORTHEAST UP THROUGH WESTERN TEXAS AND MOVING EAST FASTER THAN EXPECTED. WITH THESE TRENDS IN MIND...HAVE UPDATED MORNING FORECAST TO LOWER POPS IN THE WESTERN THIRD OF NORTH TEXAS INTO THE CHANCE CATEGORY... GOING TO SLIGHT CHANCE IN THE AFTERNOON. TOO MUCH UNCERTAINTY ON THE AFTERNOON PERIOD AND WILL MAINTAIN ONGOING FORECAST. RAIN AMOUNTS WILL BE LIGHT WITH AREAS OF FOG EXPECTED THROUGH MUCH OF THE DAY. THE APPROACHING UPPER TROUGH WILL LIKELY STEEPEN LAPSE RATES ACROSS CENTRAL/SOUTHEAST TEXAS NEAR FRONTAL WAVE TO OUR SOUTH. WILL MAINTAIN ISOLATED THUNDERSTORM MENTION ACROSS THESE AREAS. 05/ && .PREV DISCUSSION... /ISSUED 300 AM CST MON DEC 31 2012/ A WET AND COOL FORECAST IS EXPECTED TODAY INTO THIS EVENING...AS DEEP LONGWAVE TROUGH OVER THE GREAT BASIN/FOUR CORNERS REGION CONTINUES MOVING PROGRESSIVELY EAST TOWARD THE SOUTHERN PLAINS THE NEXT 24-36 HOURS. ISENTROPIC ASCENT AND WAA OVER THE TOP OF THE FRONTAL INVERSION ANCHORED AROUND 800MB HAS ALREADY BEGUN IN ERNEST ACROSS THE SOUTH PLAINS INTO WESTERN NORTH TX EARLY THIS MORNING WITH WIDESPREAD AREAS OF LIGHT RAIN OCCURRING ACROSS THESE AREAS. THE RAIN SHIELD WILL SPREAD GRADUALLY EAST ACROSS NORTH TEXAS THROUGH THE DAY WITH THE BEST SATURATION AND UPGLIDE OCCURRING ACROSS THE NORTHEAST HALF OF THE CWA WHERE RAINFALL UPWARDS TO ONE INCH OR SLIGHTLY MORE ARE NOT OUT OF THE QUESTION WITH LESSER AMOUNTS FURTHER SOUTH. ALSO WITH LOW LEVEL COLD AIR IN PLACE...THE INCREASING LIGHT TO OCCASIONALLY MODERATE RAINFALL WILL HELP BOTH VISIBILITIES AND CEILINGS FALL AFTER DAYBREAK AND THROUGHOUT MOST OF THE DAY. EXPECT THE MOST WIDESPREAD FOG AND RAIN TO OCCUR ACROSS THE NORTHERN COUNTIES...AND MORE PATCHY ACROSS THE SOUTH AND WEST WITHIN THE WARMER TEMPERATURES NEAR THE WARM FRONT. EITHER WAY...CONDITIONS WILL BE SLOPPY INTO THE EVENING HOURS. ANOTHER CHALLENGE TODAY IS HIGH TEMPERATURES...AS A FRONTAL WAVE DEVELOPS ACROSS SOUTH-CENTRAL TEXAS AND MOVES UP THROUGH THE UPPER TEXAS COAST DURING THE EVENING HOURS. MODELS HAVE DIFFERENT PERSPECTIVES ON HOW FAR NORTH THE WARM FRONT WILL MOVE INTO OUR CENTRAL TEXAS AND SOUTHEAST COUNTIES. HAVE DECIDED TO LEAN WITH A COMPROMISE AT THIS POINT AS IT IS ANYONE/S GUESS ON THIS EVOLUTION AND KEEP HIGHS IN THE 40S NORTH OF I-20...TO 55-60 IN OUR CENTRAL TEXAS AND FAR SOUTHWEST COUNTIES. LAPSE RATES WILL STEEPEN WITHIN THE NORTHWEST EDGE OF THE WARM NOSE AHEAD OF THE SYSTEM AND NEAR THE WARM FRONT ACROSS OUR SOUTHERN COUNTIES THIS AFTERNOON AND EVENING. WITH UNCERTAINTIES REGARDING WHERE THE WARM FRONT WILL RESIDE...HAVE ONLY ADDED ISOLATED THUNDERSTORMS TO AREAS SOUTHEAST OF A KILLEEN-ATHENS LINE THIS AFTERNOON/EVENING. DO NOT EXPECT SEVERE STORMS...BUT A STRONG STORM OR TWO WITH HAIL IS POSSIBLE WITH LOW FREEZING LEVELS IN PLACE. THERE COULD BE A BRIEF 3-6 HOUR WINDOW FOR SURFACE-BASED ACTIVITY IN MILAM/ROBERTSON/LEON/ANDERSON COUNTIES WHERE GUSTY WINDS COULD BE A THREAT AS WELL. MEANWHILE TONIGHT...A COLD FRONT CURRENTLY OVER THE CENTRAL HIGH PLAINS WILL ARRIVE ACROSS THE RED RIVER BY MID-LATE EVENING...THEN SURGE SLOWLY THROUGH NEW YEARS MORNING. LOOK FOR AREAS OF FOG TO CONTINUE AHEAD OF THE FRONT DURING THE EVENING HOURS WITH LIGHTER WINDS AND WARMER TEMPERATURES. IT APPEARS ANY CHANCES FOR WINTER PRECIPITATION WILL BE SHUT DOWN ACROSS OUR AREA WITH A DRIER AIRMASS ARRIVING AND WESTERLY FLOW PROVIDING ISENTROPIC DOWNGLIDE WITHIN THE LOWER LEVELS. A FEW SHOWERS WILL PERSIST ACROSS THE SOUTHEAST COUNTIES THROUGH TUESDAY MORNING. A DRY AND COLD PERIOD WILL OCCUR NEW YEARS DAY AND THROUGH THE MIDDLE PART OF THE WEEK...AS A PERSISTENT TROUGH CONTINUES ACROSS THE CENTRAL CONUS AND HELPS REINFORCE THE CHILLY AIRMASS IN PLACE WITH ADDITIONAL POLAR SURGES. HAVE GONE BELOW MOS VALUES ON HIGH TEMPERATURES WITH LITTLE IN THE WAY OF WAA OR RETURN FLOW OCCURRING THROUGH THURSDAY. MID LEVEL ENERGY DOES DEEPEN ACROSS THE OKLAHOMA INTO THE OZARKS ON THURSDAY AND HAVE HELD SLIGHT CHANCES FOR A COOL RAIN WELL SOUTH OF I-20 WHERE WEAK ISENTROPIC ASCENT MAY OCCUR...BUT CONFIDENCE IS NOT HIGH AT THIS TIME WITH MODEL DIFFERENCES ON POSITION AND STRENGTH OF THIS SHORTWAVE DROPPING SOUTH. OTHERWISE...A GRADUAL MODIFICATION ON TEMPS AND DRY CONDITIONS ARE EXPECTED FRIDAY INTO NEXT WEEKEND...THOUGH AGAIN MODEL AGREEMENT IS POOR ON OVERALL PATTERNS BOTH ALOFT AND AT THE SURFACE. 05/ && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 46 38 45 29 41 / 100 10 10 5 10 WACO, TX 53 43 48 30 44 / 80 20 20 5 10 PARIS, TX 41 37 45 26 40 / 100 30 10 10 10 DENTON, TX 45 35 41 25 40 / 90 10 10 5 10 MCKINNEY, TX 44 37 43 25 40 / 100 10 10 5 10 DALLAS, TX 46 39 45 31 41 / 100 10 10 5 10 TERRELL, TX 47 40 46 28 41 / 100 20 10 10 10 CORSICANA, TX 52 43 48 32 42 / 90 40 20 10 10 TEMPLE, TX 56 44 49 31 45 / 70 30 20 5 10 MINERAL WELLS, TX 52 35 43 25 42 / 50 10 10 5 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ /
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
556 PM EST MON DEC 31 2012 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO MOVE OFFSHORE TONIGHT...WHILE A WEAK LOW PRESSURE LOW PRESSURE SYSTEM WILL PASS ALONG THE GULF COAST OVERNIGHT AND TUESDAY. THIS SYSTEM WILL BRING A MIX OF RAIN AND WINTRY PRECIPITATION TO THE AREA TONIGHT...BEFORE PRECIPITATION TRANSITIONS TO RAIN LATE TUESDAY MORNING. THE SYSTEM WILL PAST EAST OF THE AREA TUESDAY NIGHT...WITH HIGH PRESSURE BUILDING IN FROM THE WEST ON WEDNESDAY. && .NEAR TERM /THROUGH TUESDAY/... AS OF 530 PM EST MONDAY... DEWPOINTS REMAIN VERY LOW ACROSS THE REGION ATTM AND EXPECT THIS TO KEEP MOST PRECIP ALOFT. HOWEVER AS PRECIP CONTINUES TO STREAM IN FROM THE WEST PER LATEST REGIONAL RADARS EXPECT SOME DEGREE OF SATURATION TO OCCUR ESPCLY HIGHER ELEVATIONS ALONG THE I-77 CORRIDOR THIS EVENING DESPITE MODELS SUGGESTING OTHERWISE. THUS ADDING IN A BIT MORE LOW POP ACROSS SW VA INTO TONIGHT WHERE EXPECT MAY BE SOME SLEET MIXED IN ONCE PRECIP STARTS TO REACH THE SURFACE. WILL NEED TO WATCH AND SEE IF CAN GET ENOUGH COOLING TO PUSH TEMPS DOWN TO NEAR FREEZING LATER ON WHICH MAY NOT OCCUR UNTIL LATE TONIGHT IF AT ALL. OTRW AS MORE ORGANIZED PRECIPITATION MOVES INTO THE AREA LATE TONIGHT...BELIEVE WE WILL SEE LOW LEVEL TEMPERATURES QUICKLY DROP DUE TO EVAPORATIVE COOLING...RESULTING IN PERIODS OF SNOW INITIALLY...PERHAPS CHANGING OVER TO POCKETS OF SLEET OR FREEZING RAIN TOWARD SUNRISE ESPCLY FAR NW. BECAUSE THE EVAPORATIVE COOLING MAY BE STRONG ENOUGH TO LOWER THE ATMOSPHERIC COLUMN BELOW FREEZING...RESULTING IN MAINLY SNOW...AND DUE TO THE LIGHT PRECIPITATION AMOUNTS EXPECTED...HAVE DECIDED TO FOREGO A WINTER WEATHER ADVISORY AT THIS TIME...ALTHOUGH THE EVENING SHIFT MAY DECIDE TO ISSUE ONE LATER. AFTER SUNRISE WEDNESDAY...LOW LEVEL TEMPERATURES ARE EXPECTED TO REBOUND ABOVE FREEZING...RESULTING IN MAINLY RAIN ACROSS THE AREA...WHILE PORTIONS OF SOUTHEAST WEST VIRGINIA AND THE ALLEGHANY HIGHLANDS WILL LIKELY KEEP SNOW THROUGH THE AFTERNOON. AS THE LOW PRESSURE SYSTEM CONTINUES EAST THROUGH THE DAY...EXPECT WINDS ACROSS THE AREA TO BECOME MORE NORTHWESTERLY DURING THE EVENING... ALLOWING COLDER AIR TO BUILD IN WHICH WILL CAUSE RAIN TO TRANSITION TO SNOW SHOWER ACTIVITY FROM WEST TO EAST. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... AS OF 220 PM MONDAY... POSITION OF UPPER JET AND SFC FEATURES ARE GOING TO IMPACT OUR WEATHER TUES NIGHT AS MAIN FOCUS OF PRECIP SHIFTS SOUTH OF US. STILL ENOUGH AMPLE MOISTURE EARLY TO KEEP HIGHER POPS OVER THE SOUTH AND WEST...WITH RAIN TRANSITIONING OVER TO SNOW AS COLDER AIR STARTS TO WORK BACK IN FROM THE NORTHWEST. MODELS ARE IN ENOUGH AGREEMENT AND ARE KEEPING THE THERMAL PROFILE AS MORE OF A RAIN/SNOW LAYOUT...GIVEN LACK OF DEEP SW FLOW AT 8H WITH WEAK WARM NOSE. THERE APPEARS TO BE AT TIMES A SLIGHT RISE ABOVE FREEZING EARLY THAT CANNOT RULE OUT SLEET THOUGH ITS MARGINAL SO LEFT THE PTYPE TUE EVENING AS RAIN/SNOW. LATE TUESDAY NIGHT...THE SYSTEM SHIFTS SOUTHEAST AND WILL SEE PRECIP START TO WANE. MOISTURE BECOMES SHALLOW OVER THE MTNS SUCH THAT FREEZING DRIZZLE WILL FALL IN THE HIGHER RIDGES. HIGH PRESSURE STARTS TO WORK INTO THE CENTRAL APPALACHIANS WEDNESDAY BUT THE SFC FRONT STAYS LOCKED IN OVER THE SOUTHEAST. MAY SEE THE SOUTHERN HALF OF THE CWA STAY CLOUDY WEDNESDAY WITH SW FLOW ALOFT....BUT WILL BE CLOSE. ALLOWED FOR MORE CLOUDS THOUGH SHOULD BE SOME SUNSHINE AT TIMES ESPECIALLY NORTH OF A LINE FROM I-81 IN THE SOUTHWEST TO LYNCHBURG. APPEARS MODELS START TO EDGE SOME MOISTURE BACK OUR WAY WED NIGHT- THU. MARGINAL AT BEST AND WILL KEEP POPS SMALL OVER THE SRN CWA MAINLY SOUTH OF VA/NC BORDER. IF PRECIP GETS IN EARLY ENOUGH COULD SEE A FEW SNOW FLAKES AND/OR SLEET PELLETS ACROSS SOUTHSIDE VA/NRN NC. STILL NOT EXPECTING MUCH. TEMPS THIS PERIOD STAY COOL GIVEN MORE CLOUDS. HIGHS WED-THU RANGE FROM THE MID TO UPPER 30S MTNS TO LOWER TO MID 40S EAST. LOWS ARE GOING TO BE IMPACTED BY CLOUDS AS WELL WITH 20S WEST TO AROUND 30 TO LOWER 30S SOUTHEAST. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... AS OF 230 PM EST MONDAY... LOW PRESSURE OFF THE SOUTHEAST COAST WILL CONTINUE TO MOVE EAST INTO THE ATLANTIC OCEAN THURSDAY NIGHT INTO FRIDAY MORNING. WILL ALLOW FOR A SLIGHT CHANCE OF RAIN THURSDAY EVENING IN OUR SOUTHEAST WITH ECMWF SHOWING THE NORTHERN EXTENT OF THE ASSOCIATED PRECIPITATION BRUSHING THE SOUTHEAST CORNER OF THE CWA. MODEL DIFFERENCES REMAIN WITH THE TIMING AND STRENGTH OF THE SHORTWAVE WHICH PIVOTS OUT OF THE OHIO VALLEY AROUND THE UPPER TROUGH THURSDAY NIGHT. BECAUSE OF THIS UNCERTAINTY...KEPT SOME LIGHT POPS IN THE WESTERN UPSLOPE AREAS THURSDAY NIGHT INTO FRIDAY. HIGH PRESSURE WILL BUILD EAST OUT OF THE CENTRAL U.S. ON FRIDAY. THE 1030 MB SURFACE HIGH WILL REMAIN ACROSS THE REGION DURING THE WEEKEND. WITH THE HIGH CENTER SETTLING SOUTH AND A SOUTHWEST FLOW WILL CONTINUE TO MODERATE TEMPERATURES EARLY NEXT WEEK. ANOTHER STORM MAY SPREAD MOISTURE INTO OUR REGION OUT OF THE CENTRAL PLAINS AROUND THE MIDDLE OF NEXT WEEK. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... AS OF 540 PM EST MONDAY... EXPANSIVE MID DECK CANOPY CONTINUES TO SLOWLY LOWER ACROSS THE REGION FROM WEST TO EAST ATTM...ALTHOUGH BASES STILL GENERALLY 8 KFT AND ABOVE. RADAR IS ALSO INDICATING LIGHT RETURNS MAKING THEIR WAY ACROSS THE FAR SW MOUNTAINS INTO THE AREA...BUT WITH THE LOW LEVELS STILL VERY DRY...DO NOT SEE MORE THAN LIGHT SPRINKLES OR A FEW SLEET PELLETS MAKING IT TO THE SURFACE OVER THE NEXT FEW HOURS. MODELS CONTINUE TO SLOW DOWN ANY EASTWARD PROGRESSION OF PRECIP OVERNIGHT...LIKELY DUE TO SO MUCH DRY AIR AND ONLY LIGHT PRECIP GIVEN A LACK OF A WELL DEFINED SURFACE SYSTEM. GUIDANCE ALSO REMAINS A BIT WARMER PER LESS EVAPORATIVE COOLING PROVIDED BY ONLY VERY LIGHT PRECIP WITH EVEN THE LATEST RAP AND LOCAL WRF SOLUTIONS QUITE DRY UNTIL AROUND DAYBREAK. HOWEVER...MODEL INIT REMAINS ALL OVER THE PLACE UNDER SUCH A STRUNG OUT AREA OF DEEP MOISTURE ALONG THE SRN JET AND LIKELY HAVING A HARD TIME IN WHERE TO FOCUS PRECIP ATTM. THUS HAVE KEPT IN LIGHT MIXED PRECIP FOR MANY OF THE WESTERN SITES WITH PERHAPS A PERIOD OF VERY LIGHT FREEZING RAIN POSSIBLE IN THE VALLEYS AT KLWB/KBCB TOWARD DAWN BUT CONFIDENCE LOW. OTRW INCLUDING A BIT MORE IN THE WAY OF PL MENTION AT LEAST AT THE ONSET OVERNIGHT ACROSS THE WEST WHILE LEAVING THINGS MAINLY VFR OVERNIGHT WITH ONLY SPOTTY -RA OUT EAST. PRECIPITATION WILL BECOME WIDESPREAD TUESDAY MORNING WITH A MUCH BETTER PROBABILITY OF MVFR OR EVEN IFR CONDITIONS...AND LOW TO MEDIUM CONFIDENCE THAT SITES FROM KBCB WESTWARD WILL SEE MIXED PRECIPITATION CHANGE TO RAIN BY LATE MORNING AS TEMPERATURES WARM. HOWEVER KLWB MAY GET STUCK AROUND FREEZING INTO THE AFTERNOON SO MAY BE TOUGH TO DISLODGE THE MIXED BAG THERE UNTIL PRECIP TAPERS OFF IN THE AFTERNOON. AS A SURFACE LOW PRESSURE SYSTEM PASSES THROUGH THE CAROLINAS TUESDAY AND TUESDAY NIGHT...COLDER AIR WILL MOVE INTO THE AREA. ON TUESDAY EVENING PRECIPITATION WILL CHANGE TO SNOW SHOWERS...WHICH WILL CONTINUE IN SOUTHEAST WEST VIRGINIA...INCLUDING KLWB AND KBLF INTO EARLY WEDNESDAY MORNING. VFR WEATHER IS EXPECTED WEDNESDAY AFTERNOON INTO SATURDAY FOR MOST OF THE REGION. A LOW PRESSURE SYSTEM PASSING WELL TO THE SOUTH MAY BRING SUB-VFR CONDITIONS TO DAN ON THURSDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...NF NEAR TERM...JH/NF SHORT TERM...WP LONG TERM...KK AVIATION...AMS/JH/NF
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
900 PM CST TUE JAN 1 2013 .UPDATE... THE CHALLENGE TONIGHT HAS BEEN THE TIMING OF THE ADVANCING LOWER STRATUS DECK ASSOCIATED WITH SOME WARM ADVECTION AHEAD OF THE NEXT APPROACHING LOW PRESSURE SYSTEM. THE RUC 925MB RH IS DOING A PRETTY GOOD JOB WITH IT. THE STRATUS HAS PICKED UP SPEED SINCE SUNSET...ABOUT 2-4 HOURS AHEAD OF SCHEDULE FROM EARLIER THINKING. ONCE THE CLOUDS MOVE IN...TEMPS WILL HOLD STEADY OR EVEN SLOWLY RISE...SO OUR MINS HAVE LIKELY BEEN REACHED...OR WILL BE REACHED BY MIDNIGHT. BY THEN...THE STRATUS SHOULD BE APPROACHING THE MILWAUKEE METRO AREA. THERE IS A BACK EDGE TO THIS STRATUS AS WELL...AND IT SHOULD BE MOVING FROM WEST TO EAST ACROSS THE FORECAST AREA BETWEEN 12-16Z WEDNESDAY WITH SUNSHINE THEN EXPECTED. THERE WILL BE A SLOT OF LOWER RH ON WEDNESDAY...FOLLOWED BY INCREASING CLOUDS AGAIN IN THE WAKE OF A COLD FRONT THAT MOVES THROUGH WEDNESDAY NIGHT. WE COULD SEE SOME LIGHT SNOW WITH THAT FROPA. && .AVIATION/06Z TAFS/... THE LOWER MVFR STRATUS DECK HAS PICKED UP SPEED SINCE SUNSET THIS EVENING. THE STATUS SHOULD MAKE IT TO MADISON BY 04Z AND THE MILWAUKEE AREA BY AROUND 07Z WED. THERE IS A BACK EDGE TO THE CLOUDS AND THE FIRST ESTIMATE OF CLEARING OUT OF MADISON IS AROUND 12Z AND THE MILWAUKEE METRO AREA BY 14-15Z WEDNESDAY. VFR CONDITIONS ARE THEN EXPECTED FOR A TIME ON WEDNESDAY BEFORE MORE CLOUDS ARRIVE IN THE WAKE OF A PASSING COLD FRONT WEDNESDAY EVENING. SOME LIGHT SNOW OR FLURRIES ARE POSSIBLE WITH THIS FROPA...BUT LITTLE OR NO ACCUMULATION IS EXPECTED. && .PREV DISCUSSION... /ISSUED 314 PM CST TUE JAN 1 2013/ VERY SHORT TERM...TONIGHT AND WEDNESDAY. TONIGHT - CONFIDENCE...LOW TO MEDIUM BIG CHALLENGE WITH RESPECT TO STRATUS ADVANCEMENT AND IMPACT ON LOW TEMPS. MN PORTION OF STRATUS FIELD SHOWING DECENT PUSH EAST. SRN EDGE OF STRATUS GIVE LESS CONFIDENCE FOR STRATUS OVERSPREADING THE SRN CWA LATER THIS EVENING AND OVERNIGHT. 925 WINDS TURN MORE WSW AND INCREASE A BIT WHICH WOULD TEND TO SUPPORT KEEPING THE STRATUS FROM DEVIATING TO MUCH FROM THE PRESENT COURSE. GREATEST POTENTIAL FOR NON-DIURNAL TEMP CURVE APPEARS TO BE IN THE NW CWA BASED ON LATEST SATELLITE TRENDS. OVERALL WILL GO COLDER ON TEMPS...GOING A LITTLE COLDER THAN THE COLDEST GUIDANCE. WEDNESDAY - CONFIDENCE...LOW TO MEDIUM SURFACE LOW MOVES TO NEAR LAKE SUPERIOR. RH PROGS ARE SHOWING A RELATIVE MIN ACROSS THE CWA THOUGH EVERYTHING HINGES ON THE STRATUS DECK. WITH DEVELOPING SOUTHERLY FLOW...POTENTIAL FOR STRATUS TO SHIFT FURTHER NORTH. BETTER 1000-500 MB RH HOLDS BACK FURTHER TO THE WEST CLOSER TO PRIMARY SHORTWAVE AND 850 MILLIBAR TROUGH AXIS. MODELS ALL HINTING AT 925-850 DRY SLOT ACROSS THE CWA. NAM MOS HOLDS ONTO STRATUS LONGER WITH GFS MOS SHOWING MORE SUNSHINE. PRESUMING THE STRATUS REMAINS PROGRESSIVE AND NO FURTHER EXPANSION THEN WOULD SUPPORT MORE SUNSHINE BEFORE MID DECK INCREASES AHEAD OF TROUGH. SHORT TERM...WEDNESDAY NIGHT THROUGH FRIDAY. WEDNESDAY NIGHT INTO THURSDAY...FORECAST CONFIDENCE MEDIUM. ISENTROPIC LIFT WITH WARM AIR ADVECTION COMES THROUGH IN THE AFTERNOON/EARLY EVENING WITH LITTLE MOISTURE TO WORK WITH...WITH MOISTURE CONVERGENCE AND DEPTH INCREASING ALONG SURFACE TO MID-LEVEL TROUGH AXES AS THEY MOVE ACROSS REGION WEDNESDAY EVENING. WILL KEEP CHANCE POPS GOING FOR WHAT CONTINUES TO LOOK LIKE A HIGH PROBABILITY OF OCCURRENCE/LOW PROBABILITY OF MEASURING EVENT. WILL HAVE SCATTERED FLURRIES UNTIL 500 MB TROUGH AXIS CLEARS CWA LATE THURSDAY MORNING. CLOUDS WILL HINDER TEMPERATURE DROP WEDNESDAY NIGHT...WITH LOWS IN THE TEENS. HIGHS THURSDAY WILL BE REACHED AROUND MIDDAY...THEN SLOWLY FALL THROUGH THE AFTERNOON AS THERMAL TROUGH MOVES ACROSS REGION. THURSDAY NIGHT AND FRIDAY...FORECAST CONFIDENCE MEDIUM TO HIGH. QUIET WEATHER WITH WEAK SHORT WAVE RIDGING AND SURFACE RIDGE AXIS MOVING THROUGH. SINGLE DIGIT LOWS THURSDAY NIGHT UNDER BUILDING INVERSION WITH INITIAL SURGE OF WARM AIR ADVECTION...WITH CONTINUING WAA ON WESTERLY FLOW RAISING HIGHS INTO THE MID 20S FRIDAY. LONG TERM...FRIDAY NIGHT THROUGH TUESDAY. FORECAST CONFIDENCE LOW TO MEDIUM. DIFFERENCES AMONG MODELS WITH AMOUNT OF AVAILABLE MOISTURE AND FORCING WITH SURFACE LOW CROSSING NORTHERN WISCONSIN SATURDAY LEADS TO LOW PRECIPITATION CHANCES AT THIS POINT. BUSY NEAR ZONAL PATTERN SETS UP FOR LATE WEEKEND/EARLY NEXT WEEK TIME PERIOD WITH SHORT WAVE ENERGY REMAINING NORTH ACROSS SOUTHERN CANADA...THOUGH ECMWF DOES DIG A TROUGH INTO NORTHERN WI TUESDAY...LEADING TO LOW CHANCE POPS THAT BRUSH NORTHERN CWA TUESDAY/TUESDAY NIGHT. NEAR NORMAL TEMPS EXPECTED THROUGH THE WEEKEND...WITH ABOVE NORMAL READINGS FOR EARLY NEXT WEEK. AVIATION/00Z TAFS/...MAIN CONCERN WILL BE TIMING OF MVFR STRATUS DECK INTO PARTS OF SRN WI LATER THIS EVENING AND OVERNIGHT. DECENT PUSH OF RELATIVELY HIGHER 850 MILLIBAR MOISTURE ALIGNED WITH STRATUS FIELD...AND THIS TRANSLATES EAST ACROSS SRN WI TONIGHT. LATEST SATELLITE TRENDS SUGGEST BEST POTENTIAL FOR STRATUS WILL BE ALONG AND NW OF A LINE FROM KDBQ-KMSN-KFLD. WILL ADJUST NEW TAFS TO REFLECT THESE LATEST TRENDS. LEAD SHORTWAVE ON WEDNESDAY ENCOUNTERS VERY DRY AIRMASS. BETTER POTENTIAL FOR LIGHT SNOW LOOKS TO ARRIVE WEDNESDAY NIGHT AS MAIN SHORTWAVE AND FRONTAL FORCING ARRIVES. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ UPDATE...DAVIS TONIGHT/WEDNESDAY AND AVIATION/MARINE...COLLAR WEDNESDAY NIGHT THROUGH TUESDAY...REM
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
332 PM CST MON DEC 31 2012 .VERY SHORT TERM...TONIGHT AND NEW YEARS DAY...FORECAST CONFIDENCE MEDIUM. THE GREATEST UNCERTAINTY FOR TONIGHT IS SKY COVER...WHICH WILL IMPACT THE LOW TEMPERATURES. COLD AIR ADVECTION WITH CYCLONIC FLOW ALOFT LED TO STRATUS OVER SOUTHERN WISCONSIN TODAY. THE STRATUS IS DISSIPATING FROM WEST TO EAST THIS AFTERNOON...AND ALREADY SCATTERED OUT IN MADISON. MEANWHILE...THE CIRRUS SHIELD OVER SOUTHERN WI SEEMS TO BE TAKING A LITTLE LONGER TO MOVE OUT OF THE AREA...ALTHOUGH IT APPEARS THIN ON THE VISIBLE SATELLITE IMAGERY. 925MB TEMPS WILL DROP DOWN TO -12 TO -14C OVERNIGHT. THE PRESSURE GRADIENT WILL WEAKEN AS HIGH PRESSURE SHIFTS INTO WESTERN WISCONSIN TONIGHT. SO TEMPS WILL BE SLOWER TO FALL IN THE EVENING...BUT WILL LIKELY PLUMMET AFTER MIDNIGHT...ESPECIALLY NORTHWEST OF MADISON TO FOND DU LAC SINCE THEY WILL HAVE THE LONGEST TIME TO RADIATE OUT. WHILE THE STRATUS WILL LIKELY CLEAR IN THE SOUTHEAST FORECAST AREA BEFORE MIDNIGHT...IT MAY TAKE LONGER FOR THE CIRRUS TO CLEAR...THUS KEEPING THE TEMPS HIGHER THROUGH THE NIGHT. TRIED TO STICK CLOSE TO MOS GUIDANCE IN THIS AREA. 925MB TEMPS WILL HOLD STEADY ON TUESDAY. DESPITE THE EXPECTED SUNSHINE...MAX TEMPS SHOULD BARELY RISE OUT OF THE SINGLE DIGITS BY THE AFTERNOON WITH THE EXCEPTION OF NEAR THE LAKESHORE. .SHORT TERM...TUESDAY NIGHT THROUGH THURSDAY. TUESDAY NIGHT AND WEDNESDAY...FORECAST CONFIDENCE MEDIUM TO HIGH. THERMAL TROUGH MOVES OFF TO THE EAST WITH INCREASING CLOUDS AND WARM AIR ADVECTION ON DEVELOPING SOUTHERLY WINDS AS SURFACE RIDGE SLIDES SOUTHEAST LEADING TO OVERNIGHT LOWS AROUND/JUST AFTER MIDNIGHT... THEN STEADY OR SLOWLY WARMING TEMPERATURES. RISE CONTINUES INTO WEDNESDAY AHEAD ON SOUTH WINDS AHEAD OF SHORT WAVE TROUGH AND ASSOCIATED SURFACE LOW. BEST LOWER LAYER Q-VECTOR CONVERGENCE CROSSES REGION WEDNESDAY AFTERNOON...BUT MOISTURE LACKING EXCEPT IN THE FAR NW...SO WILL LIMIT SLIGHT CHANCE POPS TO THERE. WEDNESDAY NIGHT...FORECAST CONFIDENCE MEDIUM. HAVE UPPED POPS TO CHANCE IN THE WEST AS MODELS ARE IN AGREEMENT THAT MOISTURE WILL BE DEEP ENOUGH TO REACH THE DENDRITE GROWTH ZONE FOR A FEW HOURS...WITH ENOUGH OMEGA FOR A POTENTIAL TO SQUEEZE OUT A HUNDREDTH OF AN INCH OF QPF AND A FEW TENTHS OF AN INCH OF VERY LIGHT SNOW. THIS IS STILL A HIGH PROBABILITY OF OCCURRENCE AND LOW PROBABILITY OF MEASURING SITUATION. TEMPERATURES WILL ONLY COOL SLOWLY THROUGH THE EVENING AND INTO THE OVERNIGHT...THEN DIP TOWARDS DAYBREAK WITH CLOUDS HANGING IN AND COLD AIR ADVECTION NOT KICKING IN UNTIL AFTER 06Z TO 09Z. THURSDAY...FORECAST CONFIDENCE MEDIUM COLD ADVECTION DURING THE DAY WILL PREVENT MUCH OF A TEMPERATURE RISE...HIGHS IN THE LOW TO MID 20S...AS THERMAL TROUGH MOVES ACROSS REGION DURING THE DAY. CLOUDY SKIES EARLY AND PARTLY SUNNY SKIES AT BEST IN THE AFTERNOON AS SURFACE RIDGE BUILDS IN LATE IN THE DAY. .LONG TERM...HURSDAY NIGHT THROUGH MONDAY. FORECAST CONFIDENCE LOW TO MEDIUM. MODERATING TREND BEGINS WITH MORE WESTERLY UPPER FLOW AS SHORT WAVE BREAKS DOWN WESTERN RIDGE AND BROAD SURFACE HIGH SETS UP OVER THE SOUTHERN PLAINS. MODELS DIFFER WITH PCPN CHANCES WITH THIS SHORT WAVE AS IT MOVES ACROSS THE UPPER MIDWEST SATURDAY/SUNDAY. BLENDED SOLUTIONS DID NOT CONVERGE WITH A HIGH ENOUGH POP IN ANY ONE PERIOD TO PRODUCE PRECIPITATION...THOUGH GFS/ECMWF/GEMNH ALL DO PRODUCE LIGHT QPF. WILL LEAVE DRY FOR NOW...BUT WOULD NOT BE SURPRISED TO SEE POPS IN LATER FORECASTS. WEST SOUTHWEST FLOW BEHIND THE SHORT WAVE LEADS TO DOWNSLOPE WARMING OVER THE NORTHERN PLAINS AND RAISES THICKNESSES TO SUPPORT UPPER 20S TO LOWER 30S SUNDAY...AND LOW TO MID 30S MONDAY. && .AVIATION/00Z TAFS/... COLD AIR ADVECTION WITH CYCLONIC FLOW ALOFT LED TO STRATUS OVER SOUTHERN WISCONSIN TODAY. THE AREA OF LOW CLOUDS CANNOT BE SEEN BENEATH THE DECK OF THE CIRRUS SHIELD IN VISIBLE SATELLITE IMAGERY...SO RELYING ON SURFACE OBSERVATIONS. THE NORTHWEST EDGE OF THE STRATUS DECK HAS BEEN GRADUALLY ERODING FROM THE NORTHWEST...ALREADY SCATTERING OUT AT KMSN. IT HAS NOT SPREAD INTO KENW YET...BUT ANTICIPATING THAT IT DOES FOR A FEW HOURS THIS EVENING. THE LATEST RAP SOUNDINGS IN BUFKIT PICK UP ON THE STRATUS TODAY AND NOW CLEAR THEM OUT AROUND 04Z. THE CIRRUS MAY BE A LITTLE SLOWER TO CLEAR. EXPECTING CLEAR SKIES/VFR CONDITIONS ON TUESDAY WITH LIGHTER WINDS AS HIGH PRESSURE BUILDS OVER THE AREA. && .MARINE...WINDS WILL CONTINUE TO DIMINISH OVERNIGHT AND TUESDAY AS HIGH PRESSURE BUILDS INTO THE REGION. WITH COLDER AIR SETTLING IN...WILL NEED TO WATCH FOR FREEZING SPRAY THREAT REST OF THE WEEK. WINDS WILL INCREASE OUT OF THE SOUTHWEST ON WEDNESDAY AS LOW PRESSURE MOVES ACROSS LAKE SUPERIOR. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ TONIGHT/TUESDAY AND AVIATION/MARINE...MRC TUESDAY NIGHT THROUGH MONDAY...REM
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1208 PM CST MON DEC 31 2012 .UPDATE... COLD AIR ADVECTION WITH CYCLONIC FLOW ALOFT IS LEADING TO STRATUS OVER SOUTHERN WISCONSIN THIS MORNING. TEMPERATURES WILL HOLD STEADY IN THE WEST AND FALL IN THE EAST THROUGH THE DAY. THE CLOUDS SHOULD LINGER THROUGH MUCH OF THE DAYLIGHT HOURS AND THERE IS UNCERTAINTY ABOUT HOW QUICKLY THEY WILL CLEAR OVERNIGHT. && .AVIATION/18Z TAFS/... COLD AIR ADVECTION WITH CYCLONIC FLOW ALOFT IS LEADING TO STRATUS OVER SOUTHERN WISCONSIN THIS MORNING. THE AREA OF LOW CLOUDS CANNOT BE SEEN BENEATH THE DECK OF THE THICK CIRRUS SHIELD IN VISIBLE SATELLITE IMAGERY...SO RELYING ON SURFACE OBSERVATIONS. THE SOUTHEAST EDGE OF THE STRATUS DECK APPEARS TO BE FROM WEST BEND TO SULLIVAN TO SOUTHERN DANE COUNTY TO MINERAL POINT AND PLATTEVILLE. THE SSEC GOES-E CLOUD THICKNESS PRODUCT IS SHOWING HIGH PROBABILITY FOR IFR OVER ALMOST ALL OF SOUTHERN WI EXCEPT THE LAKESHORE COUNTIES AT THIS TIME. GIVEN THE BETTER MIXING RIGHT ALONG THE LAKE...LOW CONFIDENCE ON THE STRATUS GETTING INTO MILWAUKEE AND KENOSHA. THE RAP SOUNDINGS IN BUFKIT ARE PICKING UP ON THE STRATUS TODAY AND THEY LOWER THE CEILINGS OVERNIGHT AND LINGER IT THROUGH LATE TONIGHT. FOR NOW...WILL NOT JUMP ON THAT SOLUTION AND SCATTER OUT THE CLOUDS JUST BEFORE MIDNIGHT. LOW CONFIDENCE. && .PREV DISCUSSION... /ISSUED 307 AM CST MON DEC 31 2012/ TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM. LOW LEVEL MIXING...CONVERGENCE AND SHALLOW MOISTURE MAY YET CAUSE STRATUS TO FORM VICINITY OF COLD FRONT PASSING THRU SRN WI EARLY THIS MRNG. STRONG WARM AIR ADVECTION AHEAD OF THE FRONT CAUSED TEMPS TO WARM INTO THE UPPER 20S TO LOWER 30S...WHICH WILL LIKELY BE CLOSE TO THE DAYTIME HIGHS IN THE EASTERN AREAS. EXPECT THE COLDER AIR TO SURGE INTO THE WEST EARLY THIS MRNG WITH MINIMAL TEMPERATURE RECOVERY DURING THE DAY. DIFFICULT TO IGNORE UPSTREAM SCT-BKN STRATUS FIELD OVER NORTHWEST WI INTO MN. LOW LEVEL COLD AIR ADVECTION SETTLES INTO SRN WI TODAY BEFORE BECOMING MORE NEUTRAL TONIGHT. LOW LEVEL CYCLONIC CURVATURE LINGERS OVER THE AREA AS WELL...BUT ATMOSPHERE ABOVE INVERSION REMAINS FAIRLY DRY THRU 10K FEET. BOTH NAM AND GFS SHOW LOW LEVEL RH DECREASING TODAY...BUT THIS GUIDANCE DOES NOT APPEAR TO HAVE GOOD HANDLE ON UPSTREAM STRATUS. LATEST HRRR ALSO BULLISH ON MINIMAL LOW CLOUDS. NEVER THE LESS...SRN WI WILL GET GRAZED BY PASSING HIGHER CLOUDS FROM FORCING OCCURRING ALONG BAROCLINIC ZONE JUST TO THE SOUTH. HENCE THINKING CLOUD CONDITIONS WILL VARY FROM PARTLY SUNNY TO MOSTLY CLOUDY TODAY...AND WILL REMAIN MORE PESSIMISTIC AT THIS TIME. BUILDING SUBSIDENCE ASSOCIATED WITH APPROACHING RIDGING WILL RESULT IN ANY STRATUS AND HIGHER CLOUDS CLEARING OVERNIGHT TONIGHT. 925 TEMPS TUMBLE TO BETWEEN 11 AND 14 DEGREES CELSIUS BELOW ZERO. WITH WIDESPREAD SNOW FIELD ACROSS SRN WI...EXPECT TEMPERATURES TO FALL INTO THE SINGLE DIGITS ABOVE ZERO WITH SOME BELOW ZERO READINGS. NORTHWEST WINDS CONTINUING AT 4 TO 10 KNOTS WILL CAUSE WIND CHILL READINGS TO FALL TO BETWEEN 10 AND 15 BELOW ZERO MOST AREAS LATE TONIGHT. TUESDAY THROUGH WEDNESDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM TO HIGH. SHORT TERM MODELS SHOWING MODEST 500MB SHORTWAVE TROUGH SLIDING SOUTHEAST ACROSS THE AREA TUESDAY...WITH FLOW BECOMING SOUTHWESTERLY BY 18Z WEDNESDAY...BEFORE MORE AMPLIFIED SHORTWAVE TROUGH SLIDES SOUTHEAST INTO THE REGION WEDNESDAY NIGHT. AT THE SURFACE...HIGH PRESSURE RIDGE KEEPS HOLD OF THE AREA TUESDAY AND TUESDAY NIGHT...WITH A LOW PASSING NORTH OF THE AREA WEDNESDAY NIGHT. SOME MOISTURE IN THE LOW LEVELS MOVES INTO THE AREA LATER TUESDAY NIGHT INTO WEDNESDAY. MODEST UPWARD VERTICAL MOTION SEEN WEDNESDAY NIGHT WITH SHORTWAVE...WITH AREA FORECAST SOUNDINGS SHOWING SOME MOISTURE IN THE LOW TO MID LEVELS. GFS SHOWING BETTER MOISTURE IN THE LOW LEVELS THAN THE NAM. SPOTTY LIGHT QPF SEEN IN THE AREA WEDNESDAY NIGHT ON GFS/CANADIAN/ECMWF...DRY ON NAM. WILL CONTINUE TO MENTION LOW END POPS FOR LIGHT SNOW LATE WEDNESDAY IN THE FAR WESTERN COUNTIES...AND ACROSS THE AREA WEDNESDAY NIGHT...WITH TUESDAY INTO WEDNESDAY MAINLY DRY. COLD TEMPERATURES WILL LINGER THROUGH THE PERIOD...WITH 925MB TEMPERATURES TRYING TO CLIMB INTO THE SINGLE DEGREES BELOW ZERO CELSIUS RANGE. THURSDAY THROUGH SUNDAY...FORECAST CONFIDENCE IS MEDIUM. ECMWF/GFS BOTH SHOWING SHORTWAVE TROUGH EXIT THE REGION...WITH THE ASSOCIATED SURFACE LOW SHIFTING EAST. GFS FORECAST SOUNDINGS SHOWING DRY AIR COLUMN DURING THIS TIME...SO KEPT DRY FORECAST GOING. HIGH PRESSURE THEN PASSES SOUTH OF THE REGION THURSDAY NIGHT THROUGH FRIDAY NIGHT...WITH WARM AIR ADVECTION TRYING TO MOVE INTO THE REGION. ECMWF/GFS THEN SHOW DIFFERENCES FOR SATURDAY THROUGH SUNDAY. THE GFS TRIES TO BRING A 500MB SHORTWAVE TROUGH THROUGH THE REGION SATURDAY INTO SATURDAY EVENING...ALONG WITH A COLD FRONT MOVING SOUTHEAST THROUGH THE AREA 00Z SUNDAY. DECENT MOISTURE ON GFS FORECAST SOUNDINGS ARE SEEN. LIGHT QPF OCCURS WITH THESE FEATURES. ANOTHER SHORTWAVE MOVES SOUTHEAST INTO THE REGION LATER ON SUNDAY. THE ECMWF SHOWS A 500MB SHORTWAVE TROUGH PASSING TO THE NORTHWEST OF THE AREA SUNDAY AFTERNOON AND NIGHT...WITH MODEST NORTHWEST FLOW ACROSS THE AREA. WEAK HIGH PRESSURE MOVES SOUTH OF THE AREA SATURDAY AND SATURDAY NIGHT...WITH SOUTHWEST WINDS SUNDAY. GIVEN THE DIFFERENCES...WENT WITH THE CONSENSUS POPS FOR THE WEEKEND...WHICH KEEPS THINGS DRY. TEMPERATURES WERE HANDLED IN A SIMILAR WAY...WHICH BRINGS MORE SEASONABLE TEMPERATURES TO THE AREA. AVIATION/12Z TAFS/...LOW LEVEL COLD AIR ADVECTION AND WEAK CYCLONIC CURVATURE MAY ALLOW STRATUS TO DEVELOP OVER SRN WI TODAY CONTINUING INTO THIS EVENING. HOWEVER QUITE A BIT OF DRY AIR BETWEEN 2K AND 10K FEET. ALSO NEED TO WATCH UPSTREAM STRATUS FIELD OVER SRN MN POSSIBLY ADVECTING INTO SRN WI LATER THIS MRNG AND AFTN...BUT VERY WELL COULD MIX OUT IN DRIER AIR. LATEST HRRR MODEL OPTIMISTIC ON VFR CONDITIONS TODAY...WHILE LATEST NAM CONTINUES TO BRING PERIOD OF STRATUS INTO SRN WI BEHIND CDFNT MOVING THRU NEXT FEW HOURS. HOWEVER NOT SEEING ANY INCREASE IN STRATUS OVER CENTRAL WI. AT THIS POINT...CONFIDENCE LOW ON TIMING AND COVERAGE OF MVFR LOW CLOUDS FOR THIS TAF PERIOD. MARINE...WILL CONTINUE ONGOING SMALL CRAFT ADVY THROUGH 15Z THIS MRNG. EXPECT GUSTY SOUTHWEST WINDS TO 25 KNOTS TO CONTINUE NEXT FEW HOURS AHEAD OF CDFNT WHICH WILL BE PASSING ACROSS NEARSHORE WATERS BETWEEN 11Z AND 14Z. WINDS WILL BECOME WEST AND THEN NORTHWEST UPON FRONTAL PASSAGE THIS MRNG...HOWEVER LOW LEVEL COLD AIR ADVECTION WEAK. HENCE STILL EXPECT WINDS TO MOSTLY SETTLE BELOW SMALL CRAFT ADVISORY THRESHOLD LATER THIS MRNG. WITH COLDER AIR SETTLING IN...WILL NEED TO WATCH FOR FREEZING SPRAY THREAT REST OF THE WEEK. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ UPDATE...MRC TODAY/TONIGHT AND AVIATION/MARINE...MBK TUESDAY THROUGH SUNDAY...WOOD
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
307 AM CST MON DEC 31 2012 .TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM. LOW LEVEL MIXING...CONVERGENCE AND SHALLOW MOISTURE MAY YET CAUSE STRATUS TO FORM VICINITY OF COLD FRONT PASSING THRU SRN WI EARLY THIS MRNG. STRONG WARM AIR ADVECTION AHEAD OF THE FRONT CAUSED TEMPS TO WARM INTO THE UPPER 20S TO LOWER 30S...WHICH WILL LIKELY BE CLOSE TO THE DAYTIME HIGHS IN THE EASTERN AREAS. EXPECT THE COLDER AIR TO SURGE INTO THE WEST EARLY THIS MRNG WITH MINIMAL TEMPERATURE RECOVERY DURING THE DAY. DIFFICULT TO IGNORE UPSTREAM SCT-BKN STRATUS FIELD OVER NORTHWEST WI INTO MN. LOW LEVEL COLD AIR ADVECTION SETTLES INTO SRN WI TODAY BEFORE BECOMING MORE NEUTRAL TONIGHT. LOW LEVEL CYCLONIC CURVATURE LINGERS OVER THE AREA AS WELL...BUT ATMOSPHERE ABOVE INVERSION REMAINS FAIRLY DRY THRU 10K FEET. BOTH NAM AND GFS SHOW LOW LEVEL RH DECREASING TODAY...BUT THIS GUIDANCE DOES NOT APPEAR TO HAVE GOOD HANDLE ON UPSTREAM STRATUS. LATEST HRRR ALSO BULLISH ON MINIMAL LOW CLOUDS. NEVER THE LESS...SRN WI WILL GET GRAZED BY PASSING HIGHER CLOUDS FROM FORCING OCCURRING ALONG BAROCLINIC ZONE JUST TO THE SOUTH. HENCE THINKING CLOUD CONDITIONS WILL VARY FROM PARTLY SUNNY TO MOSTLY CLOUDY TODAY...AND WILL REMAIN MORE PESSIMISTIC AT THIS TIME. BUILDING SUBSIDENCE ASSOCIATED WITH APPROACHING RIDGING WILL RESULT IN ANY STRATUS AND HIGHER CLOUDS CLEARING OVERNIGHT TONIGHT. 925 TEMPS TUMBLE TO BETWEEN 11 AND 14 DEGREES CELSIUS BELOW ZERO. WITH WIDESPREAD SNOW FIELD ACROSS SRN WI...EXPECT TEMPERATURES TO FALL INTO THE SINGLE DIGITS ABOVE ZERO WITH SOME BELOW ZERO READINGS. NORTHWEST WINDS CONTINUING AT 4 TO 10 KNOTS WILL CAUSE WIND CHILL READINGS TO FALL TO BETWEEN 10 AND 15 BELOW ZERO MOST AREAS LATE TONIGHT. .TUESDAY THROUGH WEDNESDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM TO HIGH. SHORT TERM MODELS SHOWING MODEST 500MB SHORTWAVE TROUGH SLIDING SOUTHEAST ACROSS THE AREA TUESDAY...WITH FLOW BECOMING SOUTHWESTERLY BY 18Z WEDNESDAY...BEFORE MORE AMPLIFIED SHORTWAVE TROUGH SLIDES SOUTHEAST INTO THE REGION WEDNESDAY NIGHT. AT THE SURFACE...HIGH PRESSURE RIDGE KEEPS HOLD OF THE AREA TUESDAY AND TUESDAY NIGHT...WITH A LOW PASSING NORTH OF THE AREA WEDNESDAY NIGHT. SOME MOISTURE IN THE LOW LEVELS MOVES INTO THE AREA LATER TUESDAY NIGHT INTO WEDNESDAY. MODEST UPWARD VERTICAL MOTION SEEN WEDNESDAY NIGHT WITH SHORTWAVE...WITH AREA FORECAST SOUNDINGS SHOWING SOME MOISTURE IN THE LOW TO MID LEVELS. GFS SHOWING BETTER MOISTURE IN THE LOW LEVELS THAN THE NAM. SPOTTY LIGHT QPF SEEN IN THE AREA WEDNESDAY NIGHT ON GFS/CANADIAN/ECMWF...DRY ON NAM. WILL CONTINUE TO MENTION LOW END POPS FOR LIGHT SNOW LATE WEDNESDAY IN THE FAR WESTERN COUNTIES...AND ACROSS THE AREA WEDNESDAY NIGHT...WITH TUESDAY INTO WEDNESDAY MAINLY DRY. COLD TEMPERATURES WILL LINGER THROUGH THE PERIOD...WITH 925MB TEMPERATURES TRYING TO CLIMB INTO THE SINGLE DEGREES BELOW ZERO CELSIUS RANGE. .THURSDAY THROUGH SUNDAY...FORECAST CONFIDENCE IS MEDIUM. ECMWF/GFS BOTH SHOWING SHORTWAVE TROUGH EXIT THE REGION...WITH THE ASSOCIATED SURFACE LOW SHIFTING EAST. GFS FORECAST SOUNDINGS SHOWING DRY AIR COLUMN DURING THIS TIME...SO KEPT DRY FORECAST GOING. HIGH PRESSURE THEN PASSES SOUTH OF THE REGION THURSDAY NIGHT THROUGH FRIDAY NIGHT...WITH WARM AIR ADVECTION TRYING TO MOVE INTO THE REGION. ECMWF/GFS THEN SHOW DIFFERENCES FOR SATURDAY THROUGH SUNDAY. THE GFS TRIES TO BRING A 500MB SHORTWAVE TROUGH THROUGH THE REGION SATURDAY INTO SATURDAY EVENING...ALONG WITH A COLD FRONT MOVING SOUTHEAST THROUGH THE AREA 00Z SUNDAY. DECENT MOISTURE ON GFS FORECAST SOUNDINGS ARE SEEN. LIGHT QPF OCCURS WITH THESE FEATURES. ANOTHER SHORTWAVE MOVES SOUTHEAST INTO THE REGION LATER ON SUNDAY. THE ECMWF SHOWS A 500MB SHORTWAVE TROUGH PASSING TO THE NORTHWEST OF THE AREA SUNDAY AFTERNOON AND NIGHT...WITH MODEST NORTHWEST FLOW ACROSS THE AREA. WEAK HIGH PRESSURE MOVES SOUTH OF THE AREA SATURDAY AND SATURDAY NIGHT...WITH SOUTHWEST WINDS SUNDAY. GIVEN THE DIFFERENCES...WENT WITH THE CONSENSUS POPS FOR THE WEEKEND...WHICH KEEPS THINGS DRY. TEMPERATURES WERE HANDLED IN A SIMILAR WAY...WHICH BRINGS MORE SEASONABLE TEMPERATURES TO THE AREA. && .AVIATION/12Z TAFS/...LOW LEVEL COLD AIR ADVECTION AND WEAK CYCLONIC CURVATURE MAY ALLOW STRATUS TO DEVELOP OVER SRN WI TODAY CONTINUING INTO THIS EVENING. HOWEVER QUITE A BIT OF DRY AIR BETWEEN 2K AND 10K FEET. ALSO NEED TO WATCH UPSTREAM STRATUS FIELD OVER SRN MN POSSIBLY ADVECTING INTO SRN WI LATER THIS MRNG AND AFTN...BUT VERY WELL COULD MIX OUT IN DRIER AIR. LATEST HRRR MODEL OPTIMISTIC ON VFR CONDITIONS TODAY...WHILE LATEST NAM CONTINUES TO BRING PERIOD OF STRATUS INTO SRN WI BEHIND CDFNT MOVING THRU NEXT FEW HOURS. HOWEVER NOT SEEING ANY INCREASE IN STRATUS OVER CENTRAL WI. AT THIS POINT...CONFIDENCE LOW ON TIMING AND COVERAGE OF MVFR LOW CLOUDS FOR THIS TAF PERIOD. && .MARINE...WILL CONTINUE ONGOING SMALL CRAFT ADVY THROUGH 15Z THIS MRNG. EXPECT GUSTY SOUTHWEST WINDS TO 25 KNOTS TO CONTINUE NEXT FEW HOURS AHEAD OF CDFNT WHICH WILL BE PASSING ACROSS NEARSHORE WATERS BETWEEN 11Z AND 14Z. WINDS WILL BECOME WEST AND THEN NORTHWEST UPON FRONTAL PASSAGE THIS MRNG...HOWEVER LOW LEVEL COLD AIR ADVECTION WEAK. HENCE STILL EXPECT WINDS TO MOSTLY SETTLE BELOW SMALL CRAFT ADVISORY THRESHOLD LATER THIS MRNG. WITH COLDER AIR SETTLING IN...WILL NEED TO WATCH FOR FREEZING SPRAY THREAT REST OF THE WEEK. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 9 AM CST THIS MORNING FOR LMZ643>646. && $$ TODAY/TONIGHT AND AVIATION/MARINE...MBK TUESDAY THROUGH SUNDAY...WOOD
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
446 AM EST WED JAN 2 2013 .SYNOPSIS... A FRONT WILL SHIFT SOUTH THROUGH THE REGION THIS MORNING AND STALL TO OUR SOUTH. A WEAK AREA OF LOW PRESSURE WILL RIDE EAST ALONG THE FRONT JUST TO OUR SOUTH TONIGHT AND THURSDAY. HIGH PRESSURE AND DRIER AIR WILL FILTER INTO THE REGION FRIDAY. A FRONT IS EXPECTED TO MOVE THROUGH SUNDAY...FOLLOWED BY HIGH PRESSURE AND FAIR WEATHER EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WSW UPPER FLOW OVER OUR REGION...WITH THE APPEARANCE OF AN UPPER IMPULSE WHICH HAS PASSED BY AND IS MOVING OFF TO THE NE. CURRENT SURFACE ANALYSIS INDICATES A FRONT STETCHED ACROSS THE REGION WITH BROAD LOW PRESSURE OVER THE CAROLINAS. RADAR MOSAIC CURRENTLY INDICATES AREAS OF LIGHT RAIN AND DRIZZLE OVER THE CAROLINAS...THE AREAL COVERAGE OF WHICH HAS DECREASED MARKEDLY IN THE LAST FEW HOURS BEHIND THE SHORTWAVE. THE LOW WILL QUICKLY TRACK EAST THIS MORNING...WITH THE FRONT SHIFTING SOUTH TO THE COAST BY AFTERNOON...AND STALLING TO OUR SOUTH...LEAVING AN INVERTED SURFACE TROUGH OVER THE FA. MODELS INDICATE THE BULK OF PRECIPITATION WILL MOVE OUT OF OUR FA EARLY THIS MORNING...WITH LINGERING CLOUDINESS AND PATCHY LIGHT RAIN OR DRIZZLE LINGERING OVER OUR FA. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... A WSW UPPER FLOW WILL CONTINUE TONIGHT INTO THURSDAY...WITH A SERIES OF UPPER IMPULSES RIDING ACROSS THE REGION. MODELS MAINTAIN STALLED FRONT TO OUR SOUTH...WITH INVERTED TROUGH REMAINING OVER OUR FA TONIGHT. A WAVE OF LOW PRESSURE WILL RIDE EAST ALONG THE FRONT TONIGHT AND EARLY THURSDAY...THAT WILL SPREAD SOME LIGHT RAIN BACK INTO THE REGION. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... BEHIND THE IMPULSES...THE UPPER FLOW WILL BECOME MORE WESTERLY LATE THURSDAY AND FRIDAY...ALLOWING HIGH PRESSURE AND DRIER AIR TO FILTER INTO OUR REGION. UPPER TROUGHINESS WILL REDEVELOP OVER THE CENTRAL CONUS LATE FRIDAY INTO SATURDAY...AND SHIFT EAST INTO THE EASTERN CONUS SUNDAY. SURFACE HIGH OVER OUR REGION WILL WEAKEN AND SHIFT EAST SAT NT/SUN AS A FRONT PUSHES THROUGH SUN/SUN NT. SOME QUESTIONS REGARDING MOISTURE AVAILABILITY WITH THIS FRONT. LARGE SPREAD IN GFS ENSEMBLE MOS POP NUMBERS...WITH AVERAGE POP AROUND 20...GENERALLY IN LINE WITH EXPERIMENTAL ECMWF MOS POPS. ONGOING FORECAST FOR OUR FA AND SURROUNDING DOMAINS CURRENTLY ADVERTISING POPS LESS THAN 20. LATER MODEL RUNS WILL HAVE TO BE EXAMINED FOR THE POSSIBILITY OF INTRODUCING POPS FOR THIS TIME PERIOD. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT MON/TUE. && .AVIATION /10Z WEDNESDAY THROUGH SUNDAY/... A WEAK COLD FRONT WILL SLIDE SOUTH OF THE TAF SITES BY 12Z THIS MORNING WITH WEDGE CONDITIONS AND IFR-MVFR CEILINGS 12Z-16Z. WEAK SHORT WAVE MOVED EAST THIS MORNING AND LOCAL RADARS ARE SHOWING THAT RAIN COVERAGE HAS ALSO DECREASED. PATCHY LIGHT RAIN OR DRIZZLE MAY AFFECT TAF SITES THROUGH 14Z-15Z WITH MVFR VSBYS POSSIBLE. 13KM RUC MODEL SHOWS PRECIPITATION SHOULD HAVE MOVE EAST BY 15Z. MODELS BRING DRIER TO THE FORECAST AREA BY 18Z...SO EXPECT VFR CONDITIONS FOR MOST OF THE AFTERNOON. VFR CONDITIONS WILL CONTINUE THIS EVENING. EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE THURSDAY AS A FRONTAL SYSTEM IS IN THE VICINITY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
321 AM CST WED JAN 2 2013 .DISCUSSION... 811 PM CST FOR EVENING UPDATE... HAVE TWEAKED GOING FORECAST FOR TONIGHT MAINLY TO LOWER MIN TEMPS 1-3 DEGREES MOST AREAS AND ESPECIALLY NORTHWEST...AND TO INCREASE SKY COVER AFTER MIDNIGHT ACROSS THE FAR NORTH. EARLY EVENING ANALYSIS PLACES SURFACE HIGH PRESSURE FROM THE SOUTHERN PLAINS INTO THE MID-MISSISSIPPI RIVER VALLEY. NORTHEAST EXTENT OF SURFACE RIDGE AXIS EXTENDS INTO NORTHERN IL...WHERE CLEAR SKIES WERE ALLOWING STRONG RADIATIONAL COOLING AS WINDS DECOUPLE IN/NEAR THE RIDGE AXIS. BASED ON THESE TRENDS HAVE LOWERED TEMPS ACROSS MUCH OF THE AREA BY UP TO SEVERAL DEGREES...CLOSER TO SOME OF THE COOLER MOS GUIDANCE FROM 12/18Z. OTHER FACTOR OF NOTE THIS EVENING IS THE AREA OF STRATUS OVER MUCH OF THE UPPER MISSISSIPPI VALLEY...WHICH HAS BEEN DRIFTING EAST DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. STOUT LOW LEVEL INVERSION ASSOCIATED WITH MODIFIED-ARCTIC AIR AND DENSE SNOW PACK ACROSS AREAS WEST/NORTHWEST OF THE CWA WAS NOTED IN 12Z RAOBS FROM UPSTREAM LOCATIONS. 21-00Z RAP FORECASTS OF 950-900 MB LAYER RH SEEM TO CAPTURE THE EXTENT OF THE STRATUS FAIRLY WELL...AND SUGGEST THAT THESE CLOUDS WILL SPREAD EAST INTO FAR NORTHERN IL AFTER MIDNIGHT AND PERHAPS EVEN SHIFT A LITTLE SOUTHEAST THROUGH EARLY WEDNESDAY MORNING. OTHER GUIDANCE HAS NOT HANDLED THE EXTENT/ADVECTION OF THE STRATUS VERY WELL. BASED ON SATELLITE TRENDS AND THE RAP FORECASTS...WHICH SEEM REASONABLE GIVEN THIS MOISTURE TRAPPED WITHIN STABLE LOW LEVELS...HAVE INCREASED CLOUD COVER OVER FAR NORTHERN IL LATE TONIGHT INTO EARLY WEDNESDAY. HOURLY TEMP GRIDS HAVE ALSO BEEN ADJUSTED TO SHOW A CONTINUED DECLINE UNDER CLEAR SKIES...THEN REMAIN FAIRLY STEADY OR EVEN RISE A DEGREE OR TWO FAR NORTH AS THE CLOUDS MOVE IN. CONFIDENCE IN EXTENT/COVERAGE OF STRATUS DECREASES WITH TIME...SO HAVE MAINTAINED PARTLY CLOUDY SKIES WEDNESDAY...THOUGH WOULD NOT BE SURPRISED TO SEE CLOUDS LINGER ACROSS AT LEAST THE FAR NORTHEAST PARTS OF THE FA THROUGH A PART OF WEDNESDAY MORNING. RATZER //PREV DISCUSSION... 300 PM CST AN ACTIVE PATTERN IN THE NORTHERN STREAM WILL PROVIDE SOME UPS AND DOWNS WITH TEMPERATURES FOR THE NEXT WEEK BUT VIRTUALLY NO CHANCE OF ANY DROUGHT RELIEF. TONIGHT-WEDNESDAY MAIN CONCERNS FOR OVERNIGHT INTO WEDNESDAY ARE TEMPERATURE AND CLOUD TRENDS. AREA OF STRATUS ACROSS MN-NORTHERN IA-WESTERN WIS. THIS HAS BEEN ADVECTING EAST BUT LAST FEW VISIBLE SATELLITE IMAGES SHOW SOUTHERN EDGE OF CLOUD DECK ERODING SLIGHTLY. THEREFORE THINK STRATUS WILL STAY MAINLY N OF IL...POSSIBLY JUST CLIPPING FAR NORTHERN COUNTIES AFTER MIDNIGHT. DESPITE WARM AIR ADVECTION ALOFT...EXPECT ATMOSPHERE TO DECOUPLE THIS EVENING. SHOULD BE GOOD RADIATIONAL COOLING WITH COLDEST TEMPS FAR NORTHWEST AND FAR SOUTH WHERE SNOW COVER IS IN PLACE. STRATUS COULD HAVE SOME MINOR IMPACT ON TEMPERATURES LATE TONIGHT NEAR THE WISCONSIN LINE...POSSIBLY BECOMING STEADY OR RISING A BIT TOWARD DAYBREAK. SOME SUNSHINE AND STRONG WARM AIR ADVECTION AHEAD OF APPROACHING CLIPPER WEDNESDAY SHOULD PUSH TEMPERATURES ABOVE GUIDANCE...ESPECIALLY IN LARGE SNOWLESS AREA FROM LASALLE COUNTY TO CHICAGO. CONFIDENCE HIGH. WEDNESDAY NIGHT-THURSDAY CLIPPER MOVES FROM CENTRAL CANADA TO THE NORTHERN GREAT LAKES WEDNESDAY NIGHT AND THURSDAY. SYSTEM MOVING INTO A VERY DRY AIR MASS AND BEST DYNAMICS WELL NORTH OF THE LOCAL AREA...THEREFORE ONLY EXPECT FLURRIES OR VERY LIGHT SNOW...WITH ONLY ABOUT A 20 PERCENT CHANCE OF MEASURABLE PRECIP GENERALLY NORTH OF I-80. FLURRIES MAY CONTINUE INTO THURSDAY IN COLD CYCLONIC FLOW. TEMPERATURES SHOULDN`T FALL MUCH WEDNESDAY NIGHT UNDER STRONG SOUTHWEST FLOW AND INCREASING CLOUD COVER. THEN TURNING BLUSTERY AND COLDER FOR THURSDAY. CONFIDENCE HIGH. FRIDAY-MONDAY STRONG WARM AIR ADVECTION RETURNS FRIDAY AHEAD OF NEXT CLIPPER. THIS SYSTEMS LOOKS TO BE EVEN MILDER THAN WEDNESDAY WITH 850 TEMPS OF +2 TO +4. AGAIN WILL TREND ABOVE GUIDANCE ESPECIALLY FOR AREAS WITH NO SNOW COVER. SHOULD BE NEAR OR ABOVE FREEZING FRIDAY AND MID 30S BY SATURDAY. ONLY SLIGHTLY COOLER SUNDAY BEHIND THE CLIPPER. AGAIN NO PRECIP EXPECTED WITH SATURDAYS CLIPPER. MILD DRY PATTERN CONTINUES FOR THE FIRST PART OF NEXT WEEK WITH TEMPERATURES IN THE UPPER 30S AND POSSIBLY TAGGING 40. CONFIDENCE MEDIUM-HIGH. ALLSOPP && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * MVFR CIGS MAINLY OVER 2000FT HAVE MOVED INTO THE AREA ALONG THE IL/WI LINE...AND SOME LOWER AREAS ARE NOT FAR AWAY...BUT ONLY RFD AND ORD SEEM POISED TO SEE THESE LOWER CONDITIONS. LENNING //DISCUSSION...UPDATED 09Z... THE AREA OF LOWER CLOUDS HAS MOVED INTO BOTH RFD AND ORD BUT NOT YET INTO MDW OR DPA. STILL COULD SEE SOME LOWER CONDITIONS TO AROUND 2000FT. STILL EXPECTING WINDS TO START VERY LIGHT FROM THE WEST OR WEST NORTHWEST AND GRADUALLY TURN TO THE SOUTHWEST TODAY...NEVER GETTING ESPECIALLY STRONG. FLURRIES OR LIGHT SNOW ARE POSSIBLE WEDNESDAY NIGHT INTO THURSDAY. LENNING //ORD AND MDW CONFIDENCE...UPDATED 09Z... * MEDIUM CONFIDENCE IN CEILING TRENDS THIS MORNING. LENNING //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... * THURSDAY...OCCASIONAL FLURRIES. MVFR POSSIBLE. * FRIDAY THROUGH MONDAY...DRY. VFR. && .MARINE... 242 AM CST SPENT QUITE A BIT OF TIME OVERNIGHT TRYING TO GET THE WIND TRENDS RIGHT OVER THE NEXT THREE DAYS. STILL NOT SURE THEY ARE RIGHT. THE PRESSURE GRADIENT TIGHTENS TODAY AHEAD OF A FAST MOVING LOW PRESSURE CLIPPER SYSTEM OVER THE NORTHERN PART OF THE LAKES. HOWEVER...MILDER SOUTHWESTERLY WINDS AHEAD OF THIS SYSTEM MAY NOT MIX DOWN AS WELL AS REALLY COLD WINDS WOULD BE EXPECTED TO. AFTER THE CLIPPER MOVES NORTHEAST OF THE LAKE ON THURSDAY...WINDS TURN WEST OR NORTHWEST AND THE COLDER AIR AND BETTER MIXING RETURNS OVER THE WARMER LAKE WATER. EVEN SO...TEMPERATURES ABOVE THE COLD SURFACE LAYER ARE FORECAST TO BE QUITE A BIT WARMER...INHIBITING THE ABILITY TO TAP INTO STRONGER WINDS ALOFT. BY THURSDAY NIGHT INTO FRIDAY A BROAD HIGH PRESSURE CENTER BUILDS ACROSS THE PLAINS AND FURTHER INCREASES THE GRADIENT AGAINST A LOW OVER QUEBEC. ORIGINALLY WAS THINKING THERE COULD BE PERIODS OF GALES ON THURSDAY AND FRIDAY...BUT NOW AM NOT AS SURE. THE BEST CHANCE WOULD APPEAR TO BE THURSDAY NIGHT INTO FRIDAY. OVERALL HAVE LOWERED WIND SPEEDS JUST A BIT THROUGH THE FIRST THREE DAYS COMPARED TO EARLIER THINKING. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
305 AM CST WED JAN 2 2013 .DISCUSSION... 811 PM CST FOR EVENING UPDATE... HAVE TWEAKED GOING FORECAST FOR TONIGHT MAINLY TO LOWER MIN TEMPS 1-3 DEGREES MOST AREAS AND ESPECIALLY NORTHWEST...AND TO INCREASE SKY COVER AFTER MIDNIGHT ACROSS THE FAR NORTH. EARLY EVENING ANALYSIS PLACES SURFACE HIGH PRESSURE FROM THE SOUTHERN PLAINS INTO THE MID-MISSISSIPPI RIVER VALLEY. NORTHEAST EXTENT OF SURFACE RIDGE AXIS EXTENDS INTO NORTHERN IL...WHERE CLEAR SKIES WERE ALLOWING STRONG RADIATIONAL COOLING AS WINDS DECOUPLE IN/NEAR THE RIDGE AXIS. BASED ON THESE TRENDS HAVE LOWERED TEMPS ACROSS MUCH OF THE AREA BY UP TO SEVERAL DEGREES...CLOSER TO SOME OF THE COOLER MOS GUIDANCE FROM 12/18Z. OTHER FACTOR OF NOTE THIS EVENING IS THE AREA OF STRATUS OVER MUCH OF THE UPPER MISSISSIPPI VALLEY...WHICH HAS BEEN DRIFTING EAST DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. STOUT LOW LEVEL INVERSION ASSOCIATED WITH MODIFIED-ARCTIC AIR AND DENSE SNOW PACK ACROSS AREAS WEST/NORTHWEST OF THE CWA WAS NOTED IN 12Z RAOBS FROM UPSTREAM LOCATIONS. 21-00Z RAP FORECASTS OF 950-900 MB LAYER RH SEEM TO CAPTURE THE EXTENT OF THE STRATUS FAIRLY WELL...AND SUGGEST THAT THESE CLOUDS WILL SPREAD EAST INTO FAR NORTHERN IL AFTER MIDNIGHT AND PERHAPS EVEN SHIFT A LITTLE SOUTHEAST THROUGH EARLY WEDNESDAY MORNING. OTHER GUIDANCE HAS NOT HANDLED THE EXTENT/ADVECTION OF THE STRATUS VERY WELL. BASED ON SATELLITE TRENDS AND THE RAP FORECASTS...WHICH SEEM REASONABLE GIVEN THIS MOISTURE TRAPPED WITHIN STABLE LOW LEVELS...HAVE INCREASED CLOUD COVER OVER FAR NORTHERN IL LATE TONIGHT INTO EARLY WEDNESDAY. HOURLY TEMP GRIDS HAVE ALSO BEEN ADJUSTED TO SHOW A CONTINUED DECLINE UNDER CLEAR SKIES...THEN REMAIN FAIRLY STEADY OR EVEN RISE A DEGREE OR TWO FAR NORTH AS THE CLOUDS MOVE IN. CONFIDENCE IN EXTENT/COVERAGE OF STRATUS DECREASES WITH TIME...SO HAVE MAINTAINED PARTLY CLOUDY SKIES WEDNESDAY...THOUGH WOULD NOT BE SURPRISED TO SEE CLOUDS LINGER ACROSS AT LEAST THE FAR NORTHEAST PARTS OF THE FA THROUGH A PART OF WEDNESDAY MORNING. RATZER //PREV DISCUSSION... 300 PM CST AN ACTIVE PATTERN IN THE NORTHERN STREAM WILL PROVIDE SOME UPS AND DOWNS WITH TEMPERATURES FOR THE NEXT WEEK BUT VIRTUALLY NO CHANCE OF ANY DROUGHT RELIEF. TONIGHT-WEDNESDAY MAIN CONCERNS FOR OVERNIGHT INTO WEDNESDAY ARE TEMPERATURE AND CLOUD TRENDS. AREA OF STRATUS ACROSS MN-NORTHERN IA-WESTERN WIS. THIS HAS BEEN ADVECTING EAST BUT LAST FEW VISIBLE SATELLITE IMAGES SHOW SOUTHERN EDGE OF CLOUD DECK ERODING SLIGHTLY. THEREFORE THINK STRATUS WILL STAY MAINLY N OF IL...POSSIBLY JUST CLIPPING FAR NORTHERN COUNTIES AFTER MIDNIGHT. DESPITE WARM AIR ADVECTION ALOFT...EXPECT ATMOSPHERE TO DECOUPLE THIS EVENING. SHOULD BE GOOD RADIATIONAL COOLING WITH COLDEST TEMPS FAR NORTHWEST AND FAR SOUTH WHERE SNOW COVER IS IN PLACE. STRATUS COULD HAVE SOME MINOR IMPACT ON TEMPERATURES LATE TONIGHT NEAR THE WISCONSIN LINE...POSSIBLY BECOMING STEADY OR RISING A BIT TOWARD DAYBREAK. SOME SUNSHINE AND STRONG WARM AIR ADVECTION AHEAD OF APPROACHING CLIPPER WEDNESDAY SHOULD PUSH TEMPERATURES ABOVE GUIDANCE...ESPECIALLY IN LARGE SNOWLESS AREA FROM LASALLE COUNTY TO CHICAGO. CONFIDENCE HIGH. WEDNESDAY NIGHT-THURSDAY CLIPPER MOVES FROM CENTRAL CANADA TO THE NORTHERN GREAT LAKES WEDNESDAY NIGHT AND THURSDAY. SYSTEM MOVING INTO A VERY DRY AIR MASS AND BEST DYNAMICS WELL NORTH OF THE LOCAL AREA...THEREFORE ONLY EXPECT FLURRIES OR VERY LIGHT SNOW...WITH ONLY ABOUT A 20 PERCENT CHANCE OF MEASURABLE PRECIP GENERALLY NORTH OF I-80. FLURRIES MAY CONTINUE INTO THURSDAY IN COLD CYCLONIC FLOW. TEMPERATURES SHOULDN`T FALL MUCH WEDNESDAY NIGHT UNDER STRONG SOUTHWEST FLOW AND INCREASING CLOUD COVER. THEN TURNING BLUSTERY AND COLDER FOR THURSDAY. CONFIDENCE HIGH. FRIDAY-MONDAY STRONG WARM AIR ADVECTION RETURNS FRIDAY AHEAD OF NEXT CLIPPER. THIS SYSTEMS LOOKS TO BE EVEN MILDER THAN WEDNESDAY WITH 850 TEMPS OF +2 TO +4. AGAIN WILL TREND ABOVE GUIDANCE ESPECIALLY FOR AREAS WITH NO SNOW COVER. SHOULD BE NEAR OR ABOVE FREEZING FRIDAY AND MID 30S BY SATURDAY. ONLY SLIGHTLY COOLER SUNDAY BEHIND THE CLIPPER. AGAIN NO PRECIP EXPECTED WITH SATURDAYS CLIPPER. MILD DRY PATTERN CONTINUES FOR THE FIRST PART OF NEXT WEEK WITH TEMPERATURES IN THE UPPER 30S AND POSSIBLY TAGGING 40. CONFIDENCE MEDIUM-HIGH. ALLSOPP && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * MVFR CIGS SEEM TO BE ON THE WAY...AND IF THEY MAKE IT INTO THE TERMINALS...MAY END UP STICKING AROUND A WHILE. LENNING //DISCUSSION...UPDATED 06Z... HAVE BEEN TRACKING AN AREA OF LOWER CLOUDS SINCE LAST EVENING. THIS HAS MOVED INTO NW IL AND LIKELY WILL BE INTO RFD WITHIN AN HOUR OR SO. WHETHER IT GETS TO ORD IS LESS CERTAIN...AND INTO MDW EVEN MORE UNCERTAIN. ELECTED TO KEEP THE SAME TIMING AS PREVIOUS TAFS...BUT INCREASED COVERAGE FROM SCT TO BKN AT ORD. WINDS START VERY LIGHT FROM THE WEST OR NORTHWEST AND GRADUALLY TURN TO THE SOUTHWEST TODAY...NEVER GETTING ESPECIALLY STRONG. FLURRIES OR LIGHT SNOW ARE POSSIBLE WEDNESDAY NIGHT INTO THURSDAY. LENNING //ORD AND MDW CONFIDENCE...UPDATED 06Z... * ONLY MEDIUM CONFIDENCE IN CIG TRENDS...BUT HIGHER CONFIDENCE THEY WILL AT LEAST STAY ABOVE IFR AND RANGE FROM 1500 TO 2500 FT. LENNING //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... * THURSDAY...OCCASIONAL FLURRIES. MVFR POSSIBLE. * FRIDAY THROUGH MONDAY...DRY. VFR. && .MARINE... 242 AM CST SPENT QUITE A BIT OF TIME OVERNIGHT TRYING TO GET THE WIND TRENDS RIGHT OVER THE NEXT THREE DAYS. STILL NOT SURE THEY ARE RIGHT. THE PRESSURE GRADIENT TIGHTENS TODAY AHEAD OF A FAST MOVING LOW PRESSURE CLIPPER SYSTEM OVER THE NORTHERN PART OF THE LAKES. HOWEVER...MILDER SOUTHWESTERLY WINDS AHEAD OF THIS SYSTEM MAY NOT MIX DOWN AS WELL AS REALLY COLD WINDS WOULD BE EXPECTED TO. AFTER THE CLIPPER MOVES NORTHEAST OF THE LAKE ON THURSDAY...WINDS TURN WEST OR NORTHWEST AND THE COLDER AIR AND BETTER MIXING RETURNS OVER THE WARMER LAKE WATER. EVEN SO...TEMPERATURES ABOVE THE COLD SURFACE LAYER ARE FORECAST TO BE QUITE A BIT WARMER...INHIBITING THE ABILITY TO TAP INTO STRONGER WINDS ALOFT. BY THURSDAY NIGHT INTO FRIDAY A BROAD HIGH PRESSURE CENTER BUILDS ACROSS THE PLAINS AND FURTHER INCREASES THE GRADIENT AGAINST A LOW OVER QUEBEC. ORIGINALLY WAS THINKING THERE COULD BE PERIODS OF GALES ON THURSDAY AND FRIDAY...BUT NOW AM NOT AS SURE. THE BEST CHANCE WOULD APPEAR TO BE THURSDAY NIGHT INTO FRIDAY. OVERALL HAVE LOWERED WIND SPEEDS JUST A BIT THROUGH THE FIRST THREE DAYS COMPARED TO EARLIER THINKING. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1151 PM CST TUE JAN 1 2013 .DISCUSSION... 811 PM CST FOR EVENING UPDATE... HAVE TWEAKED GOING FORECAST FOR TONIGHT MAINLY TO LOWER MIN TEMPS 1-3 DEGREES MOST AREAS AND ESPECIALLY NORTHWEST...AND TO INCREASE SKY COVER AFTER MIDNIGHT ACROSS THE FAR NORTH. EARLY EVENING ANALYSIS PLACES SURFACE HIGH PRESSURE FROM THE SOUTHERN PLAINS INTO THE MID-MISSISSIPPI RIVER VALLEY. NORTHEAST EXTENT OF SURFACE RIDGE AXIS EXTENDS INTO NORTHERN IL...WHERE CLEAR SKIES WERE ALLOWING STRONG RADIATIONAL COOLING AS WINDS DECOUPLE IN/NEAR THE RIDGE AXIS. BASED ON THESE TRENDS HAVE LOWERED TEMPS ACROSS MUCH OF THE AREA BY UP TO SEVERAL DEGREES...CLOSER TO SOME OF THE COOLER MOS GUIDANCE FROM 12/18Z. OTHER FACTOR OF NOTE THIS EVENING IS THE AREA OF STRATUS OVER MUCH OF THE UPPER MISSISSIPPI VALLEY...WHICH HAS BEEN DRIFTING EAST DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. STOUT LOW LEVEL INVERSION ASSOCIATED WITH MODIFIED-ARCTIC AIR AND DENSE SNOW PACK ACROSS AREAS WEST/NORTHWEST OF THE CWA WAS NOTED IN 12Z RAOBS FROM UPSTREAM LOCATIONS. 21-00Z RAP FORECASTS OF 950-900 MB LAYER RH SEEM TO CAPTURE THE EXTENT OF THE STRATUS FAIRLY WELL...AND SUGGEST THAT THESE CLOUDS WILL SPREAD EAST INTO FAR NORTHERN IL AFTER MIDNIGHT AND PERHAPS EVEN SHIFT A LITTLE SOUTHEAST THROUGH EARLY WEDNESDAY MORNING. OTHER GUIDANCE HAS NOT HANDLED THE EXTENT/ADVECTION OF THE STRATUS VERY WELL. BASED ON SATELLITE TRENDS AND THE RAP FORECASTS...WHICH SEEM REASONABLE GIVEN THIS MOISTURE TRAPPED WITHIN STABLE LOW LEVELS...HAVE INCREASED CLOUD COVER OVER FAR NORTHERN IL LATE TONIGHT INTO EARLY WEDNESDAY. HOURLY TEMP GRIDS HAVE ALSO BEEN ADJUSTED TO SHOW A CONTINUED DECLINE UNDER CLEAR SKIES...THEN REMAIN FAIRLY STEADY OR EVEN RISE A DEGREE OR TWO FAR NORTH AS THE CLOUDS MOVE IN. CONFIDENCE IN EXTENT/COVERAGE OF STRATUS DECREASES WITH TIME...SO HAVE MAINTAINED PARTLY CLOUDY SKIES WEDNESDAY...THOUGH WOULD NOT BE SURPRISED TO SEE CLOUDS LINGER ACROSS AT LEAST THE FAR NORTHEAST PARTS OF THE FA THROUGH A PART OF WEDNESDAY MORNING. RATZER //PREV DISCUSSION... 300 PM CST AN ACTIVE PATTERN IN THE NORTHERN STREAM WILL PROVIDE SOME UPS AND DOWNS WITH TEMPERATURES FOR THE NEXT WEEK BUT VIRTUALLY NO CHANCE OF ANY DROUGHT RELIEF. TONIGHT-WEDNESDAY MAIN CONCERNS FOR OVERNIGHT INTO WEDNESDAY ARE TEMPERATURE AND CLOUD TRENDS. AREA OF STRATUS ACROSS MN-NORTHERN IA-WESTERN WIS. THIS HAS BEEN ADVECTING EAST BUT LAST FEW VISIBLE SATELLITE IMAGES SHOW SOUTHERN EDGE OF CLOUD DECK ERODING SLIGHTLY. THEREFORE THINK STRATUS WILL STAY MAINLY N OF IL...POSSIBLY JUST CLIPPING FAR NORTHERN COUNTIES AFTER MIDNIGHT. DESPITE WARM AIR ADVECTION ALOFT...EXPECT ATMOSPHERE TO DECOUPLE THIS EVENING. SHOULD BE GOOD RADIATIONAL COOLING WITH COLDEST TEMPS FAR NORTHWEST AND FAR SOUTH WHERE SNOW COVER IS IN PLACE. STRATUS COULD HAVE SOME MINOR IMPACT ON TEMPERATURES LATE TONIGHT NEAR THE WISCONSIN LINE...POSSIBLY BECOMING STEADY OR RISING A BIT TOWARD DAYBREAK. SOME SUNSHINE AND STRONG WARM AIR ADVECTION AHEAD OF APPROACHING CLIPPER WEDNESDAY SHOULD PUSH TEMPERATURES ABOVE GUIDANCE...ESPECIALLY IN LARGE SNOWLESS AREA FROM LASALLE COUNTY TO CHICAGO. CONFIDENCE HIGH. WEDNESDAY NIGHT-THURSDAY CLIPPER MOVES FROM CENTRAL CANADA TO THE NORTHERN GREAT LAKES WEDNESDAY NIGHT AND THURSDAY. SYSTEM MOVING INTO A VERY DRY AIR MASS AND BEST DYNAMICS WELL NORTH OF THE LOCAL AREA...THEREFORE ONLY EXPECT FLURRIES OR VERY LIGHT SNOW...WITH ONLY ABOUT A 20 PERCENT CHANCE OF MEASURABLE PRECIP GENERALLY NORTH OF I-80. FLURRIES MAY CONTINUE INTO THURSDAY IN COLD CYCLONIC FLOW. TEMPERATURES SHOULDN`T FALL MUCH WEDNESDAY NIGHT UNDER STRONG SOUTHWEST FLOW AND INCREASING CLOUD COVER. THEN TURNING BLUSTERY AND COLDER FOR THURSDAY. CONFIDENCE HIGH. FRIDAY-MONDAY STRONG WARM AIR ADVECTION RETURNS FRIDAY AHEAD OF NEXT CLIPPER. THIS SYSTEMS LOOKS TO BE EVEN MILDER THAN WEDNESDAY WITH 850 TEMPS OF +2 TO +4. AGAIN WILL TREND ABOVE GUIDANCE ESPECIALLY FOR AREAS WITH NO SNOW COVER. SHOULD BE NEAR OR ABOVE FREEZING FRIDAY AND MID 30S BY SATURDAY. ONLY SLIGHTLY COOLER SUNDAY BEHIND THE CLIPPER. AGAIN NO PRECIP EXPECTED WITH SATURDAYS CLIPPER. MILD DRY PATTERN CONTINUES FOR THE FIRST PART OF NEXT WEEK WITH TEMPERATURES IN THE UPPER 30S AND POSSIBLY TAGGING 40. CONFIDENCE MEDIUM-HIGH. ALLSOPP && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * MVFR CIGS SEEM TO BE ON THE WAY...AND IF THEY MAKE IT INTO THE TERMINALS...MAY END UP STICKING AROUND A WHILE. LENNING //DISCUSSION...UPDATED 06Z... HAVE BEEN TRACKING AN AREA OF LOWER CLOUDS SINCE LAST EVENING. THIS HAS MOVED INTO NW IL AND LIKELY WILL BE INTO RFD WITHIN AN HOUR OR SO. WHETHER IT GETS TO ORD IS LESS CERTAIN...AND INTO MDW EVEN MORE UNCERTAIN. ELECTED TO KEEP THE SAME TIMING AS PREVIOUS TAFS...BUT INCREASED COVERAGE FROM SCT TO BKN AT ORD. WINDS START VERY LIGHT FROM THE WEST OR NORTHWEST AND GRADUALLY TURN TO THE SOUTHWEST TODAY...NEVER GETTING ESPECIALLY STRONG. FLURRIES OR LIGHT SNOW ARE POSSIBLE WEDNESDAY NIGHT INTO THURSDAY. LENNING //ORD AND MDW CONFIDENCE...UPDATED 06Z... * ONLY MEDIUM CONFIDENCE IN CIG TRENDS...BUT HIGHER CONFIDENCE THEY WILL AT LEAST STAY ABOVE IFR AND RANGE FROM 1500 TO 2500 FT. LENNING //OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z... * THURSDAY...OCCASIONAL FLURRIES. MVFR POSSIBLE. * FRIDAY THROUGH MONDAY...DRY. VFR. && .MARINE... 202 PM CST I ISSUED A SMALL CRAFT ADVISORY EARLIER THIS MORNING FOR THE INDIANA SHORES DUE TO NORTHWESTERLY WINDS OF 20 TO 25 KT AND BUILDING WAVES UP TO 4 TO 6 FT. THE WINDS HAVE BEEN SLOWLY DIMINISHING OVER THE PAST COUPLE OF HOURS...WITH WINDS OUT OF THE NORTHWEST IN THE 15 TO 20 KT RANGE. I WILL KEEP THIS ADVISORY GOING THROUGH MOST OF TONIGHT AS WAVES WILL LIKELY BE SLOW TO SUBSIDE BELOW 4 FEET. OTHERWISE...THE MAIN CONCERNS OVER THE LAKE WILL BE ON THURSDAY THROUGH FRIDAY AS THE ANOTHER EPISODE OF HIGH WINDS IS EXPECTED. ON THURSDAY...A POTENT AREA OF HIGH PRESSURE IS EXPECTED TO BUILD ACROSS THE CENTRAL AND SOUTHERN PLAINS...EASTWARD ACROSS THE MIDDLE MISSISSIPPI VALLEY. AT THE SAME TIME...AN AREA OF LOW PRESSURE WILL TRACK EASTWARD ACROSS THE UPPER GREAT LAKES. THESE TWO PRESSURE SYSTEMS WILL RESULT IN A DECENT PRESSURE GRADIENT ACROSS THE LAKE LATER THURSDAY...LIKELY RESULTING IN AN UPTAKE IN THE WIND SPEEDS AS THEY BECOME WESTERLY. AT THIS TIME IT APPEARS THE WINDS WILL BE AROUND 30 KT. HOWEVER...I CANNOT RULE OUT A FEW GALES...SO I WILL CONTINUE TO THE MENTION. THE WINDS DONT LOOK TO DIMINISH MUCH INTO FRIDAY AS ANOTHER WEAK TROUGH OF LOW PRESSURE TRACKS TO THE NORTH...ESSENTIALLY MAINTAINING THE STRENGTH OF THE GRADIENT. FROM SATURDAY INTO NEXT WEEK IT APPEARS THE WEATHER PATTERN ACROSS THE UPPER MIDWEST AND UPPER GREAT LAKES WILL REMAIN VERY ACTIVE. IN FACT...IT APPEARS A PARADE OF LOW PRESSURE SYSTEMS WILL CONTINUE TO TRACK ACROSS THE UPPER GREAT LAKES EVERY DAY OR TWO THROUGH AT LEAST THE MIDDLE OF NEXT WEEK AS HIGH PRESSURE DOMINATES ACROSS THE SOUTHERN CONUS. OVERALL THIS LOOKS TO RESULT IN A FAIRLY PROLONGED PERIOD OF ELEVATED WEST TO SOUTHWESTERLY WINDS OF 25 TO 30 KT THROUGH MUCH OF THE PERIOD. THERE COULD ALSO BE A FEW PERIODS OF GALE FORCE WINDS DURING THE PERIOD. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 4 AM WEDNESDAY. && $$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
501 AM EST WED JAN 2 2013 .SYNOPSIS... ISSUED AT 449 AM EST WED JAN 2 2013 OCCASIONAL LAKE EFFECT SNOW SHOWERS WILL CONTINUE FOR MOST OF THIS WEEK...WITH A MORE ROBUST PERIOD OF LAKE ENHANCED SNOW THURSDAY...AS THE NEXT CLIPPER SYSTEM MOVES THROUGH THE AREA. WARMER AND DRIER AIR THEN BEGIN TO MOVE INTO THE REGION FRIDAY AND OVER THE WEEKEND FOR SIGNIFICANTLY LOWER SNOW CHANCES. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 449 AM EST WED JAN 2 2013 WEAK HIGH PRESSURE WAS SETTLED IN OVER THE REGION...WITH MUCH COLDER AIR ACROSS ONTARIO DRAINING IN ACROSS EASTERN LAKE SUPERIOR...ENHANCING A LOW LEVEL COLD FRONT/CONVERGENCE. THIS CONVERGENCE AND AIR FLOW OVER LAKE SUPERIOR PRODUCED QUITE THE MODERATE/INTENSE SNOW BAND THAT FILTERED IN MAINLY JUST THE PARADISE AREA A FEW HOURS BACK. THIS BAND OF SNOW HAS WEAKENED OVER EASTERN UPPER DUE TO LOSS OF A DECENT FETCH. THE REST OF NRN MICHIGAN WAS SEEING A RAPIDLY APPROACHING STRATUS LAYER FROM LAKE MICHIGAN AND WISCONSIN...WITH A CONTINUED EXPECTATION TO SWEEP OVER ALL OF THE REGION. CLEAR SKIES IN SPOTS ACROSS FAR NRN LOWER AND NE LOWER WILL BECOME CLOUDY AGAIN. FLURRIES WERE STILL FAIRLY PREVALENT OUTSIDE OF THE CLEAR REGIONS...AND THE UPSTREAM CLOUDS ALSO CONTAIN FLURRIES. RADAR SHOWING THIS IS THE CASE...WITH NEW ECHOES POPPING UP OVER LAKE MICHIGAN. TEMPERATURES WERE IN THE TEENS AND LOWER 20S. NEXT ALBERTA CLIPPER WAS MOVING INTO FAR NRN MN WITH TROUGHING EXTENDING EASTWARD AND CONNECTING WITH THE ENHANCED TROUGHING FROM THE COLD AIR DRAINAGE/COLD FRONT. THE SYSTEM COLD FRONT WAS DRAPED THROUGH EASTERN ND/SD AND DOWN INTO NEBRASKA. DEEPER MOISTURE WAS SEEN VIA SATELLITE ALONG AND BEHIND THE COLD FRONT...AS WELL AROUND THE NRN PERIPHERY OF THE LOW PRESSURE. TODAY AND TONIGHT...WILL BE RAMPING FOR THE ARRIVAL OF THE CLIPPER LATE TONIGHT AND INTO THURSDAY. THE STRATUS FROM WISCONSIN WAS ERODING FROM THE SW...WITHIN WEAK WARM AIR ADVECTION INTO THE CLOUD LAYER. NOT WORRIED TOO MUCH ABOUT THIS WARM ADVECTION ERODING THE STRATUS FOR US...SINCE LOW LEVEL TEMPS OF -8C TO -10C HOLD THROUGHOUT THE DAY...SUFFICIENT COLD ENOUGH TO KEEP NOT ONLY CLOUDS IN PLACE...BUT TO ALSO ALLOW FOR THE CONTINUED GENERATION OF LAKE EFFECT FLURRIES. THESE FLURRIES WILL BE WITHIN WEST FLOW REGIMES THIS MORNING...THEN SW FLOW REGIMES AS WINDS BACK AHEAD OF THE APPROACHING LOW PRESSURE. ONE FLY IN THE OINTMENT THAT COULD HAVE SOME SIGNIFICANT RAMIFICATIONS IN THE SNOWFALL/AMOUNTS IS FOR THE DRAINAGE FLOW FROM ONTARIO...EXPECTED TO ENHANCE CONVERGENCE OVER LAKE HURON...WHICH COULD NEAR THE NE LOWER SHORELINE. HI RES MODELS/LATEST RUC ARE STEADFAST ON THIS IDEA BY DAYBREAK...WITH THE DEVELOPMENT OF ANOTHER MODERATE/INTENSE LAKE SNOW BAND. CONFIDENCE IN THIS ISN`T THE GREATEST...DUE IN PART TO THE DRAINAGE LAGGING THE HI RES TIMING (NOT EVEN INTO THE SAULT RIGHT NOW)...AND THAT MIXING INTO THE MORNING MIGHT KEEP THE CONVERGENCE WELL OUT INTO NRN LAKE HURON...NOT THREATENING OUR COASTAL AREAS. THIS IS SOMETHING TO KEEP A CLOSE EYE ON...AS THE ARRIVAL OF THE CONVERGENCE INTO FAR NRN LOWER AND EASTERN UPPER...WOULD ENHANCE CONVERGENCE AND RESULT IN STRONGER THAN EXPECTED SNOWS. AGAIN...NOT ENTIRELY SOLD ON THIS. DID INCREASE CHANCES FOR SEEING BONA FIDE SNOWS AND SMALL ACCUMULATIONS...BUT FEELING IS FOR ANY ACCUMS TO REMAIN UNDER AN INCH. WE WILL HAVE TO WAIT FOR INCREASED SW WINDS AND DEEPER MOISTURE AHEAD OF THE CLIPPER`S COLD FRONT. THIS HAPPENS THROUGH THE NIGHT...BUT MAINLY AFTER MIDNIGHT. INCREASED MOISTURE FLUX OFF THE LAKES WILL HELP...BUT INVERSION HEIGHTS RISING TO MAYBE 4500-5000FEET WITH DELTA T`S UNDER 15C...AND NO GOOD SUPPORT ALOFT WILL MORE LIKELY RESULT IN ACCUMULATIONS IN THE 1-2 INCH RANGE WITH A SLIVER OF AN AREA ACROSS CENTRAL CHIP/MACK COUNTIES...AND EMMET COUNTY SEEING UP TO 3 INCHES. IF THERE IS A LAKE HURON BAND OF SNOW THAT DEVELOP THIS MORNING...THE SW FLOW WILL GRADUALLY PUSH THIS SNOW IN ACROSS DRUMMOND ISLAND BEFORE DEPARTING EAST OF THERE. VERY DIFFICULT MESOSCALE FORECAST IN THE SHORT TERM. && .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 449 AM EST WED JAN 2 2013 ENERGETIC SPLIT FLOW PATTERN SET TO CONTINUE...WITH ONE LAST NORTHERN STREAM ORIGINATED SHORTWAVE SET TO VISIT OUR AREA LATER TONIGHT INTO THURSDAY. AFTERWARD...NORTHERN STREAM PROGGED TO RETREAT NORTH...BOTTLING UP THE ARCTIC COLD WELL TO OUR NORTH FOR THE FORESEEABLE FUTURE...PART OF A BURGEONING POSITIVE AO SIGNATURE AND EAST DISPLACED NORTH ATLANTIC BLOCKING. NOT TO SAY THE PATTERN DOESN`T HOLD AT LEAST SOME SNOW POTENTIAL FOR THE SNOW ENTHUSIASTS AMONGST US...WITH THURSDAY`S LEAD CHARGING SYSTEM HAVING THE LOOKS OF A RATHER SNEAKY LAKE ENHANCED SNOW EVENT FOR THE TRADITIONAL SNOWBELTS. TAKING A LOOK EVEN FURTHER OUT...MAY SEE THE BEGINNINGS OF THE INFAMOUS "JANUARY THAW" HEADING INTO NEXT WORK WEEK...WITH WELL AGREED UPON PROGS SUGGESTING A FURTHER RELAXATION OF THE NORTHERN STREAM AND A FLOODING OF MODIFIED PACIFIC AIR ACROSS THE CONUS. LARGE SCALE INDICES WOULD TEND TO AGREE...ALTHOUGH WITH DOMINATE POLAR VORTEX ON THIS SIDE OF THE GLOBE...HAVE SOME SUSPICION NORTHERN STREAM WILL NOT YIELD AS AGGRESSIVELY AS SOME PROGS WOULD SUGGEST. GETTING A TOUCH AHEAD OF MYSELF...AND STILL HAVE AMPLE CONCERNS IN THE SHORT TERM PORTION OF THE LONG TERM TO DEAL WITH...MOST NOTABLY THURSDAY`S SNOW POTENTIAL. DEFINITELY AN INTRIGUING SYSTEM FOR THURSDAY AS FAST MOVING AREA OF LOW PRESSURE SLICES ACROSS LAKE SUPERIOR EARLY...DRAGGING AN EQUALLY FAST MOVING COLD FRONT THROUGH NORTHERN MICHIGAN DURING THE MORNING. WHILE CORE OF BETTER MID LEVEL DYNAMICS LOOK TO PASS BY JUST TO OUR NORTH..STILL DECENT SLUG OF UPWARD QG SUPPORT ALONG SHARP SHORTWAVE TROUGH AXIS PASSING OVERHEAD. DEEP LAYER MOISTURE NOTHING TO WRITE HOME ABOUT...WITH PWAT VALUES STRUGGLING TO EXCEED A QUARTER OF AN INCH. STILL...WOULD EXPECT AT LEAST SOME SYNOPTIC DRIVEN SNOWS TO ACCOMPANY SHORTWAVE PASSAGE DURING THE MORNING. WILD CARD REMAINS LAKE ENHANCEMENT POTENTIAL...BOTH ALONG AND PROCEEDING COLD FRONTAL PASSAGE. PREFRONTAL AIRMASS MORE THAN COLD ENOUGH TO SUPPORT LAKE ENHANCED SNOWS...PARTICULARLY AS CONVERGENCE IS MAXIMIZED ALONG FRONTAL SLOPE. TEMPERATURES COOL FURTHER IMMEDIATELY BEHIND THE FRONT...WITH H85 READINGS APPROACHING THE NEGATIVE MIDDLE TEENS BY AFTERNOON. MOISTURE REMAINS ABUNDANT UNTIL MID LEVEL TROUGH PASSAGE DURING THE AFTERNOON...SUGGESTING AT LEAST A SEVERAL HOUR WINDOW OF GOOD LAKE ENHANCED SNOWS IN FAVORED WNW-NW FLOW AREAS THROUGH THE MORNING. MODEL DERIVED SOUNDING BEAR THIS POTENTIAL OUT (ESPECIALLY NAM-BUFR SOUNDINGS WHICH HAVE SOME SUPPORT FROM LATEST ECMWF PROGS)...WITH QUICK UPTICK TO NEAR H75 INVERSION LEVELS...ALL THE WHILE OMEGA MAX BECOMES CENTERED IN PRIME DGZ. HOW WILL ALL THIS PLAY OUT? KINDA ENVISION A PERIOD OF DECENT SNOWS ACROSS NORTHWEST LOWER/EASTERN UPPER MICHIGAN WITH THE FRONTAL PASSAGE...WITH A QUICK TRANSITION TO WNW-NW LAKE ENHANCED SNOWS THROUGH THE REMAINDER OF THE MORNING. ACTIVITY SHOULD BEGIN TO WIND DOWN RATHER QUICKLY DURING THE AFTERNOON...AND ESPECIALLY THURSDAY EVENING...AS MOISTURE RAPIDLY DEPARTS. CIPS ANALOGS FOR THIS EVENT HONING IN ON SOME INTERESTING NUMBERS...WITH IMPACT GUIDANCE SHOWING 6 TO 8 INCH AMOUNTS IN THE TRADITIONAL SNOWBELTS OF BOTH PENINSULAS. QUICK MOVEMENT OF SYSTEM AND SOME LINGERING CONCERN WITH EXACT THERMAL STRUCTURES (SOME GUIDANCE NOT QUITE AS COLD) PREVENTS FROM GOING THIS AGGRESSIVE...BUT WILL GO AHEAD A RAISE INHERITED SNOW AMOUNTS BY AT LEAST AN INCH OR SO...BRINGING DAYTIME ACCUMULATIONS TO 2 TO 3 INCHES IN FAVORED AREAS. IF TRENDS HOLD...MAY EVENTUALLY NEED AN ADVISORY FOR AT LEAST SOME COUNTIES OF NORTHWEST LOWER AND EASTERN UPPER MICHIGAN. SYSTEM EXITS JUST AS QUICK AS IT ARRIVES...WITH ANY LINGERING SNOW SHOWERS COMING TO AN END OVERNIGHT THURSDAY AS MOISTURE DEPARTS AND WAA COMMENCES. CONDITIONS LOOK QUIET AND A TOUCH WARMER TO END THE WORK WEEK AS THE NORTHERN STREAM RELAXATION BEGINS...LETTING HEIGHTS BUILD AND SOUTHWEST WINDS TO DEVELOP ON NORTH SIDE OF SOUTHERN HIGH PRESSURE. NEXT MOISTURE STARVED SYSTEM ARRIVES OVER THE WEEKEND...PERHAPS BRINGING A FEW SNOW SHOWERS ONCE AGAIN SATURDAY INTO SATURDAY NIGHT. TEMPERATURES APPEAR TOO MARGINAL FOR ANY PRE AND POST FRONTAL LAKE ENHANCEMENT. MAIN STORM TRACK CONTINUES TO TREND FURTHER NORTH HEADING INTO NEXT WORK WEEK. PACIFIC AIR STILL APPEARS RATHER AGGRESSIVE...WITH LATEST PROGS SUGGESTING MUCH OF THE NORTHERN CONUS FLOODED BY ABOVE NORMAL TEMPERATURES BY THE MIDDLE OF NEXT WEEK. FORECAST WILL REFLECT THE BEGINNING OF THIS WARM-UP...WITH READINGS RUNNING SEVERAL DEGREES ABOVE NORMAL BY MONDAY AND TUESDAY. AS MENTIONED EARLIER...NOT ENTIRELY SOLD YET ON THIS AGGRESSIVE WARMING...AND STILL PLAUSIBLE FOR BRIEF NORTHERN STREAM FORAYS TO KEEP THE BULK OF THE WARMING OFF TO OUR WEST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1140 PM EST TUE JAN 1 2013 MVFR CONDITIONS ARE EXPECTED TO CONTINUE FOR THE TERMINAL SITES THE REST OF THE NIGHT...THOUGH WITH A BRIEF PERIOD OF CLEARING POSSIBLE AROUND PLN THE NEXT FEW HOURS. CEILINGS WILL PROBABLY GRADUALLY LOWER AFTER 08Z AS THICKER STRATUS ACROSS WISCONSIN DRIFTS INTO THE REGION...WITH A SMALL POTENTIAL FOR A BRIEF PERIOD OF IFR AROUND TVC/MBL. PERIODIC FLURRIES WILL ALSO CONTINUE FOR JUST ABOUT ALL SITES...BUT WITH VISBYS NO WORSE THAN 5-6SM. THAT MAY CHANGE A BIT ACROSS NORTHWEST LOWER MICHIGAN LATER WEDNESDAY AS THE FLOW BACKS MORE SOUTHWESTERLY...PERHAPS BRINGING SOME SLIGHTLY MORE ROBUST SNOW SHOWERS AROUND PLN AND MAYBE TVC/MBL. WINDS THROUGH THE PERIOD SHOULD BE FAIRLY LIGHT...GENERALLY IN THE 5-15 KNOT RANGE. && .MARINE... ISSUED AT 449 AM EST WED JAN 2 2013 WINDS WILL GRADUALLY WEAKEN TODAY...BEFORE PICKING BACK UP AGAIN TONIGHT...IN ADVANCE OF AN ALBERTA CLIPPER AND ASSOCIATED COLD FRONT. THE TIGHTEST GRADIENT WILL RESIDE ACROSS THE NW LOWER NEARSHORE...THROUGH THE STRAITS AND INTO NRN LAKE HURON. OVERLAKE INSTABILITY WILL BE DEEPENING WITH THE ABILITY TO TAP ADVISORY LEVEL GUSTS IN THESE AREAS. IN ADDITION...THIS DEEPENING INSTABILITY...AND DEEPER MOISTURE FROM THE CLIPPER...WILL RESULT IN ENHANCED LAKE EFFECT SNOW SHOWERS. THE WINDS WILL BE STRONGEST BEHIND THE COLD FRONT...THURSDAY THROUGH FRIDAY...AND THESE ADVISORIES WILL NOT ONLY NEED TO BE EXTENDED...BUT THE REMAINDER OF THE NEARSHORE WATERS WILL LIKELY NEED ADVISORIES TOO. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR LHZ345>349. LM...SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR LMZ323-342- 344>346. LS...NONE. && $$ SYNOPSIS...MB SHORT TERM...SD LONG TERM...MB AVIATION...LAWRENCE MARINE...SD
AREA FORECAST DISCUSSION
NWS GLASGOW MT
241 AM MST WED JAN 2 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH FRIDAY... A DIFFICULT BEGINNING TO THE FORECAST THIS MORNING ACROSS NORTHEAST MONTANA. A FEW SNOW SHOWERS ARE FLOATING AROUND THE SOUTHERN ZONES...BUT UPSTREAM FAIRLY CLEAR VIA THE IR SAT THIS MORNING. BETHUNE AND SCHULER RADARS TO OUR NORTH HAVE THE SNOW SHOWERS MAINLY EAST OF ASSININBOIA THIS MORNING TRACKING SOUTHEAST. WILL KEEP THE HIGHER POPS ALONG THE NORTH DAKOTA BORDER EVEN THOUGH CONFIDENCE IS FALLING OFF QUICKLY WITH THE NAM/GFS AS PER THE HRRR WHICH KEEPS THE AREA DRY THROUGH THE MORNING HOURS. IF THE EAST STARTS TO CLEAR MIGHT HAVE TO MAKE AN EARLY MORNING UPDATE TO IMPROVE THE WEATHER IN THE EAST TODAY. BY TONIGHT THE RIDGE BUILDS IN...AS PER ALL GUIDANCE PRODUCTS WHICH WILL DRY THE AREA OUT ABOVE 2700 FEET IN THE ATMOSPHERE AND BEGIN TO WARM IT UP AT THE HIGHER ELEVATIONS. THE LOWER ELEVATIONS WILL STAY BELOW THE INVERSION AND IN THE SHALLOW COLD AIR WILL LOOKS TO HANG ON UNTIL FRIDAY. MAKES FOR A DIFFICULT TEMPERATURE FORECAST... ABOVE 3000 FEET 30S AND 40S LOOK GOOD... BELOW 2500 SORRY BUT LOOKS FOR THE TEENS AND 20S WITH OVERNIGHT LOWS IN THE SINGLE DIGITS. ITS THE IN BETWEEN THOSE TWO ELEVATIONS THAT WILL BOUNCE AROUND. FRIDAY THE RIDGE GETS FLATTENED BY A DRY SHORTWAVE WHICH SHOULD ALLOW MIXING DOWN INTO THE VALLEYS AND ALLOW THE VALLEY BOTTOM LOCATIONS TO ENJOY A LITTLE WARMER AIR... CHINOOK WINDS SHOULD KICK UP IN THE WESTERN ZONES AND HIGHER ELEVATIONS IN THE EAST WITH ABOVE NORMAL TEMPERATURES TO FINISH THE SHORT TERM OF THE FORECAST. PROTON .LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY... THERE HAS NOT BEEN MUCH CHANGE IN THE THINKING AS FAR AS THE EXTENDED IS CONCERNED. AN UPPER RIDGE BUILDS INTO THE FORECAST AREA ON SATURDAY WHICH WILL LEAD TO MOSTLY SUNNY SKIES AND DRY CONDITIONS. SATURDAY NIGHT UNDER MAINLY CLEAR SKIES IF WINDS BECOME LIGHT THERE COULD BE THE POTENTIAL FOR THE FORMATION OF FREEZING FOG. THE 00Z ECMWF BRINGS IN THE NEXT SHORTWAVE FOR SUNDAY AFTERNOON AND SO THAT SHOULD HELP TO MIX OUT ANY FOG THAT DOES DEVELOP. THE 00Z GFS TAKES THIS WAVE FURTHER TO THE NORTH...KEEPING THE CWA IN NORTHWEST FLOW ALOFT. REGARDLESS...MODEL GUIDANCE IS DRY FOR THE PERIOD SO DID NOT INSERT A MENTION OF POPS WITH THIS WAVE. THE ECMWF BRINGS YET ANOTHER UPPER WAVE THROUGH THE AREA ON MONDAY AFTERNOON AND THE GFS AGAIN TRACKS IT TO THE NORTH. ONCE AGAIN DO NOT EXPECT MUCH PRECIPITATION TO RESULT. TUESDAY AND BEYOND...TOWARDS THE MIDDLE OF THE WEEK MODELS ARE CONVERGING ON THE IDEA OF THE WESTERN HALF OF THE U.S. BEING DOMINATED BY SPLIT FLOW ALOFT. THIS PLACES NORTHEAST MONTANA UNDER THE INFLUENCE OF AN UPPER RIDGE ASSOCIATED WITH THE DRIER NORTHERN BRANCH. THUS...HAVE MODERATING TEMPERATURES IN THE GRIDS THROUGH THE MIDDLE OF NEXT WEEK. MID 40S FOR HIGHS SEEM LIKE A REAL POSSIBILITY IN SOME LOCATIONS IN PHILLIPS AND PETROLEUM COUNTIES AS WELL AS PARTS OF WESTERN GARFIELD COUNTY AS THE ECMWF WARMS 850MB TEMPERATURES AS HIGH AS +8C BY TUESDAY AFTERNOON. WENT AHEAD AND PUT IN SLIGHT CHANCE POPS ACROSS THE ENTIRE CWA FOR WEDNESDAY INTO THURSDAY AS LONG RANGE MODELS ARE IN AGREEMENT THAT A VIGOROUS SHORTWAVE WILL TRANSLATE ACROSS NORTHEAST MONTANA SOMETIME DURING THIS PERIOD. NOT TOO CONFIDENT THIS FAR OUT BUT FELT IT DID WARRENT A MENTION SINCE THERE IS DECENT MODEL AGREEMENT. MALIAWCO && .AVIATION... A SHORTWAVE TROUGH EXITS THE REGION DURING THE DAYTIME HOURS AS A RIDGE BUILDS IN FROM THE WEST. THIS WILL PUT AN END TO ANY ISOLATED TO SCATTERED SNOW SHOWERS IN THE VICINITY IN THE MORNING. ANY MVFR OR IFR CEILINGS WILL ALSO BEGIN TO LIFT AS SKIES CLEAR THROUGHOUT THE DAY. THUS...ANTICIPATING A RETURN TO VFR BY THE LATE MORNING OR AFTERNOON. EXPECT WEST TO NORTHWEST SURFACE WINDS DURING THE DAY RANGING FROM 10-20 KTS. MALIAWCO && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1013 AM EST WED JAN 2 2013 .SYNOPSIS... ISSUED AT 449 AM EST WED JAN 2 2013 OCCASIONAL LAKE EFFECT SNOW SHOWERS WILL CONTINUE FOR MOST OF THIS WEEK...WITH A MORE ROBUST PERIOD OF LAKE ENHANCED SNOW THURSDAY...AS THE NEXT CLIPPER SYSTEM MOVES THROUGH THE AREA. WARMER AND DRIER AIR THEN BEGIN TO MOVE INTO THE REGION FRIDAY AND OVER THE WEEKEND FOR SIGNIFICANTLY LOWER SNOW CHANCES. && .UPDATE... ISSUED AT 1008 AM EST WED JAN 2 2013 NO BIG CHANGES TO THE FORECAST. EXTENDED LAKE EFFECT FLURRIES INTO EARLY AFTERNOON ACROSS EASTERN COUNTIES AS THE FLOW REMAINS WESTERLY (BEFORE BACKING INTO THE SOUTHWEST LATER ON). OTHERWISE...LOWERED MAXES BY A DEGREE OR TWO MOST SPOTS (EXCEPT FOR NEAR THE LAKE MICHIGAN SHORELINE WHERE HAD TO ADD A DEGREE OR SO). UPDATE ISSUED AT 638 AM EST WED JAN 2 2013 FORECAST GOING ALONG TO PLAN THIS MORNING WITH FLURRIES IN THE WESTERLY FLOW REGIMES...EXPANDED FROM INVADING WIDESPREAD LOW LEVEL STRATUS. THIS STRATUS HAS COVERED ALMOST EVERYONE (ALPENA WITHIN THE NEXT HOUR OR SO). THERE IS A LOSS OF CONFIDENCE IN THE DEVELOPMENT OF A PRETTY GOOD BAND OF SNOW OUT OVER LAKE HURON. THE DRAINAGE FLOW INTO THIS AREA...IS LAGGING BY A FEW HOURS. SO REMOVED THE HIGH CHANCES FOR SNOW...AND CERTAINLY FOR THE NE LOWER COAST. WILL HOLD ON TO SOME HOPE BY EARLY AFTERNOON...BUT NOT SO SURE ABOUT THAT EITHER. ALL OF NRN LOWER SHOULD MAINLY SEE FLURRIES...UNTIL LATER THIS AFTERNOON...WHEN INCREASING MOISTURE AND A SW FLOW MAY BRING A FEW TENTHS TO THE NW LOWER COAST. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 449 AM EST WED JAN 2 2013 WEAK HIGH PRESSURE WAS SETTLED IN OVER THE REGION...WITH MUCH COLDER AIR ACROSS ONTARIO DRAINING IN ACROSS EASTERN LAKE SUPERIOR...ENHANCING A LOW LEVEL COLD FRONT/CONVERGENCE. THIS CONVERGENCE AND AIR FLOW OVER LAKE SUPERIOR PRODUCED QUITE THE MODERATE/INTENSE SNOW BAND THAT FILTERED IN MAINLY JUST THE PARADISE AREA A FEW HOURS BACK. THIS BAND OF SNOW HAS WEAKENED OVER EASTERN UPPER DUE TO LOSS OF A DECENT FETCH. THE REST OF NRN MICHIGAN WAS SEEING A RAPIDLY APPROACHING STRATUS LAYER FROM LAKE MICHIGAN AND WISCONSIN...WITH A CONTINUED EXPECTATION TO SWEEP OVER ALL OF THE REGION. CLEAR SKIES IN SPOTS ACROSS FAR NRN LOWER AND NE LOWER WILL BECOME CLOUDY AGAIN. FLURRIES WERE STILL FAIRLY PREVALENT OUTSIDE OF THE CLEAR REGIONS...AND THE UPSTREAM CLOUDS ALSO CONTAIN FLURRIES. RADAR SHOWING THIS IS THE CASE...WITH NEW ECHOES POPPING UP OVER LAKE MICHIGAN. TEMPERATURES WERE IN THE TEENS AND LOWER 20S. NEXT ALBERTA CLIPPER WAS MOVING INTO FAR NRN MN WITH TROUGHING EXTENDING EASTWARD AND CONNECTING WITH THE ENHANCED TROUGHING FROM THE COLD AIR DRAINAGE/COLD FRONT. THE SYSTEM COLD FRONT WAS DRAPED THROUGH EASTERN ND/SD AND DOWN INTO NEBRASKA. DEEPER MOISTURE WAS SEEN VIA SATELLITE ALONG AND BEHIND THE COLD FRONT...AS WELL AROUND THE NRN PERIPHERY OF THE LOW PRESSURE. TODAY AND TONIGHT...WILL BE RAMPING FOR THE ARRIVAL OF THE CLIPPER LATE TONIGHT AND INTO THURSDAY. THE STRATUS FROM WISCONSIN WAS ERODING FROM THE SW...WITHIN WEAK WARM AIR ADVECTION INTO THE CLOUD LAYER. NOT WORRIED TOO MUCH ABOUT THIS WARM ADVECTION ERODING THE STRATUS FOR US...SINCE LOW LEVEL TEMPS OF -8C TO -10C HOLD THROUGHOUT THE DAY...SUFFICIENT COLD ENOUGH TO KEEP NOT ONLY CLOUDS IN PLACE...BUT TO ALSO ALLOW FOR THE CONTINUED GENERATION OF LAKE EFFECT FLURRIES. THESE FLURRIES WILL BE WITHIN WEST FLOW REGIMES THIS MORNING...THEN SW FLOW REGIMES AS WINDS BACK AHEAD OF THE APPROACHING LOW PRESSURE. ONE FLY IN THE OINTMENT THAT COULD HAVE SOME SIGNIFICANT RAMIFICATIONS IN THE SNOWFALL/AMOUNTS IS FOR THE DRAINAGE FLOW FROM ONTARIO...EXPECTED TO ENHANCE CONVERGENCE OVER LAKE HURON...WHICH COULD NEAR THE NE LOWER SHORELINE. HI RES MODELS/LATEST RUC ARE STEADFAST ON THIS IDEA BY DAYBREAK...WITH THE DEVELOPMENT OF ANOTHER MODERATE/INTENSE LAKE SNOW BAND. CONFIDENCE IN THIS ISN`T THE GREATEST...DUE IN PART TO THE DRAINAGE LAGGING THE HI RES TIMING (NOT EVEN INTO THE SAULT RIGHT NOW)...AND THAT MIXING INTO THE MORNING MIGHT KEEP THE CONVERGENCE WELL OUT INTO NRN LAKE HURON...NOT THREATENING OUR COASTAL AREAS. THIS IS SOMETHING TO KEEP A CLOSE EYE ON...AS THE ARRIVAL OF THE CONVERGENCE INTO FAR NRN LOWER AND EASTERN UPPER...WOULD ENHANCE CONVERGENCE AND RESULT IN STRONGER THAN EXPECTED SNOWS. AGAIN...NOT ENTIRELY SOLD ON THIS. DID INCREASE CHANCES FOR SEEING BONA FIDE SNOWS AND SMALL ACCUMULATIONS...BUT FEELING IS FOR ANY ACCUMS TO REMAIN UNDER AN INCH. WE WILL HAVE TO WAIT FOR INCREASED SW WINDS AND DEEPER MOISTURE AHEAD OF THE CLIPPER`S COLD FRONT. THIS HAPPENS THROUGH THE NIGHT...BUT MAINLY AFTER MIDNIGHT. INCREASED MOISTURE FLUX OFF THE LAKES WILL HELP...BUT INVERSION HEIGHTS RISING TO MAYBE 4500-5000FEET WITH DELTA T`S UNDER 15C...AND NO GOOD SUPPORT ALOFT WILL MORE LIKELY RESULT IN ACCUMULATIONS IN THE 1-2 INCH RANGE WITH A SLIVER OF AN AREA ACROSS CENTRAL CHIP/MACK COUNTIES...AND EMMET COUNTY SEEING UP TO 3 INCHES. IF THERE IS A LAKE HURON BAND OF SNOW THAT DEVELOP THIS MORNING...THE SW FLOW WILL GRADUALLY PUSH THIS SNOW IN ACROSS DRUMMOND ISLAND BEFORE DEPARTING EAST OF THERE. VERY DIFFICULT MESOSCALE FORECAST IN THE SHORT TERM. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 449 AM EST WED JAN 2 2013 ENERGETIC SPLIT FLOW PATTERN SET TO CONTINUE...WITH ONE LAST NORTHERN STREAM ORIGINATED SHORTWAVE SET TO VISIT OUR AREA LATER TONIGHT INTO THURSDAY. AFTERWARD...NORTHERN STREAM PROGGED TO RETREAT NORTH...BOTTLING UP THE ARCTIC COLD WELL TO OUR NORTH FOR THE FORESEEABLE FUTURE...PART OF A BURGEONING POSITIVE AO SIGNATURE AND EAST DISPLACED NORTH ATLANTIC BLOCKING. NOT TO SAY THE PATTERN DOESN`T HOLD AT LEAST SOME SNOW POTENTIAL FOR THE SNOW ENTHUSIASTS AMONGST US...WITH THURSDAY`S LEAD CHARGING SYSTEM HAVING THE LOOKS OF A RATHER SNEAKY LAKE ENHANCED SNOW EVENT FOR THE TRADITIONAL SNOWBELTS. TAKING A LOOK EVEN FURTHER OUT...MAY SEE THE BEGINNINGS OF THE INFAMOUS "JANUARY THAW" HEADING INTO NEXT WORK WEEK...WITH WELL AGREED UPON PROGS SUGGESTING A FURTHER RELAXATION OF THE NORTHERN STREAM AND A FLOODING OF MODIFIED PACIFIC AIR ACROSS THE CONUS. LARGE SCALE INDICES WOULD TEND TO AGREE...ALTHOUGH WITH DOMINATE POLAR VORTEX ON THIS SIDE OF THE GLOBE...HAVE SOME SUSPICION NORTHERN STREAM WILL NOT YIELD AS AGGRESSIVELY AS SOME PROGS WOULD SUGGEST. GETTING A TOUCH AHEAD OF MYSELF...AND STILL HAVE AMPLE CONCERNS IN THE SHORT TERM PORTION OF THE LONG TERM TO DEAL WITH...MOST NOTABLY THURSDAY`S SNOW POTENTIAL. DEFINITELY AN INTRIGUING SYSTEM FOR THURSDAY AS FAST MOVING AREA OF LOW PRESSURE SLICES ACROSS LAKE SUPERIOR EARLY...DRAGGING AN EQUALLY FAST MOVING COLD FRONT THROUGH NORTHERN MICHIGAN DURING THE MORNING. WHILE CORE OF BETTER MID LEVEL DYNAMICS LOOK TO PASS BY JUST TO OUR NORTH..STILL DECENT SLUG OF UPWARD QG SUPPORT ALONG SHARP SHORTWAVE TROUGH AXIS PASSING OVERHEAD. DEEP LAYER MOISTURE NOTHING TO WRITE HOME ABOUT...WITH PWAT VALUES STRUGGLING TO EXCEED A QUARTER OF AN INCH. STILL...WOULD EXPECT AT LEAST SOME SYNOPTIC DRIVEN SNOWS TO ACCOMPANY SHORTWAVE PASSAGE DURING THE MORNING. WILD CARD REMAINS LAKE ENHANCEMENT POTENTIAL...BOTH ALONG AND PROCEEDING COLD FRONTAL PASSAGE. PREFRONTAL AIRMASS MORE THAN COLD ENOUGH TO SUPPORT LAKE ENHANCED SNOWS...PARTICULARLY AS CONVERGENCE IS MAXIMIZED ALONG FRONTAL SLOPE. TEMPERATURES COOL FURTHER IMMEDIATELY BEHIND THE FRONT...WITH H85 READINGS APPROACHING THE NEGATIVE MIDDLE TEENS BY AFTERNOON. MOISTURE REMAINS ABUNDANT UNTIL MID LEVEL TROUGH PASSAGE DURING THE AFTERNOON...SUGGESTING AT LEAST A SEVERAL HOUR WINDOW OF GOOD LAKE ENHANCED SNOWS IN FAVORED WNW-NW FLOW AREAS THROUGH THE MORNING. MODEL DERIVED SOUNDING BEAR THIS POTENTIAL OUT (ESPECIALLY NAM-BUFR SOUNDINGS WHICH HAVE SOME SUPPORT FROM LATEST ECMWF PROGS)...WITH QUICK UPTICK TO NEAR H75 INVERSION LEVELS...ALL THE WHILE OMEGA MAX BECOMES CENTERED IN PRIME DGZ. HOW WILL ALL THIS PLAY OUT? KINDA ENVISION A PERIOD OF DECENT SNOWS ACROSS NORTHWEST LOWER/EASTERN UPPER MICHIGAN WITH THE FRONTAL PASSAGE...WITH A QUICK TRANSITION TO WNW-NW LAKE ENHANCED SNOWS THROUGH THE REMAINDER OF THE MORNING. ACTIVITY SHOULD BEGIN TO WIND DOWN RATHER QUICKLY DURING THE AFTERNOON...AND ESPECIALLY THURSDAY EVENING...AS MOISTURE RAPIDLY DEPARTS. CIPS ANALOGS FOR THIS EVENT HONING IN ON SOME INTERESTING NUMBERS...WITH IMPACT GUIDANCE SHOWING 6 TO 8 INCH AMOUNTS IN THE TRADITIONAL SNOWBELTS OF BOTH PENINSULAS. QUICK MOVEMENT OF SYSTEM AND SOME LINGERING CONCERN WITH EXACT THERMAL STRUCTURES (SOME GUIDANCE NOT QUITE AS COLD) PREVENTS FROM GOING THIS AGGRESSIVE...BUT WILL GO AHEAD A RAISE INHERITED SNOW AMOUNTS BY AT LEAST AN INCH OR SO...BRINGING DAYTIME ACCUMULATIONS TO 2 TO 3 INCHES IN FAVORED AREAS. IF TRENDS HOLD...MAY EVENTUALLY NEED AN ADVISORY FOR AT LEAST SOME COUNTIES OF NORTHWEST LOWER AND EASTERN UPPER MICHIGAN. SYSTEM EXITS JUST AS QUICK AS IT ARRIVES...WITH ANY LINGERING SNOW SHOWERS COMING TO AN END OVERNIGHT THURSDAY AS MOISTURE DEPARTS AND WAA COMMENCES. CONDITIONS LOOK QUIET AND A TOUCH WARMER TO END THE WORK WEEK AS THE NORTHERN STREAM RELAXATION BEGINS...LETTING HEIGHTS BUILD AND SOUTHWEST WINDS TO DEVELOP ON NORTH SIDE OF SOUTHERN HIGH PRESSURE. NEXT MOISTURE STARVED SYSTEM ARRIVES OVER THE WEEKEND...PERHAPS BRINGING A FEW SNOW SHOWERS ONCE AGAIN SATURDAY INTO SATURDAY NIGHT. TEMPERATURES APPEAR TOO MARGINAL FOR ANY PRE AND POST FRONTAL LAKE ENHANCEMENT. MAIN STORM TRACK CONTINUES TO TREND FURTHER NORTH HEADING INTO NEXT WORK WEEK. PACIFIC AIR STILL APPEARS RATHER AGGRESSIVE...WITH LATEST PROGS SUGGESTING MUCH OF THE NORTHERN CONUS FLOODED BY ABOVE NORMAL TEMPERATURES BY THE MIDDLE OF NEXT WEEK. FORECAST WILL REFLECT THE BEGINNING OF THIS WARM-UP...WITH READINGS RUNNING SEVERAL DEGREES ABOVE NORMAL BY MONDAY AND TUESDAY. AS MENTIONED EARLIER...NOT ENTIRELY SOLD YET ON THIS AGGRESSIVE WARMING...AND STILL PLAUSIBLE FOR BRIEF NORTHERN STREAM FORAYS TO KEEP THE BULK OF THE WARMING OFF TO OUR WEST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 638 AM EST WED JAN 2 2013 WIDESPREAD MVFR CIGS WILL BE COMMON FOR EVERYONE WITH FLURRIES AND NO VSBY RESTRICTIONS. CONFIDENCE IS FAIRLY HIGH HERE. THE MVFR CIGS WILL GO THROUGH THE NIGHT...ACTUALLY LOWER TO POSSIBLE IFR LATE TONIGHT WHEN DEEPER MOISTURE AND INCREASING ACTIVE LAKE EFFECT AND A SLIGHTLY MORE WESTERLY WIND BRINGS IN SOME BETTER SNOWS. WINDS WILL BE WESTERLY BACKING MORE SW WITH TIME...BUT 10KTS OR LESS. && .MARINE... ISSUED AT 449 AM EST WED JAN 2 2013 WINDS WILL GRADUALLY WEAKEN TODAY...BEFORE PICKING BACK UP AGAIN TONIGHT...IN ADVANCE OF AN ALBERTA CLIPPER AND ASSOCIATED COLD FRONT. THE TIGHTEST GRADIENT WILL RESIDE ACROSS THE NW LOWER NEARSHORE...THROUGH THE STRAITS AND INTO NRN LAKE HURON. OVERLAKE INSTABILITY WILL BE DEEPENING WITH THE ABILITY TO TAP ADVISORY LEVEL GUSTS IN THESE AREAS. IN ADDITION...THIS DEEPENING INSTABILITY...AND DEEPER MOISTURE FROM THE CLIPPER...WILL RESULT IN ENHANCED LAKE EFFECT SNOW SHOWERS. THE WINDS WILL BE STRONGEST BEHIND THE COLD FRONT...THURSDAY THROUGH FRIDAY...AND THESE ADVISORIES WILL NOT ONLY NEED TO BE EXTENDED...BUT THE REMAINDER OF THE NEARSHORE WATERS WILL LIKELY NEED ADVISORIES TOO. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR LHZ345>349. LM...SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR LMZ323-342- 344>346. LS...NONE. && $$ UPDATE...AS SYNOPSIS...MB SHORT TERM...SD LONG TERM...MB AVIATION...SD MARINE...SD
AREA FORECAST DISCUSSION
NWS GAYLORD MI
649 AM EST WED JAN 2 2013 .SYNOPSIS... ISSUED AT 449 AM EST WED JAN 2 2013 OCCASIONAL LAKE EFFECT SNOW SHOWERS WILL CONTINUE FOR MOST OF THIS WEEK...WITH A MORE ROBUST PERIOD OF LAKE ENHANCED SNOW THURSDAY...AS THE NEXT CLIPPER SYSTEM MOVES THROUGH THE AREA. WARMER AND DRIER AIR THEN BEGIN TO MOVE INTO THE REGION FRIDAY AND OVER THE WEEKEND FOR SIGNIFICANTLY LOWER SNOW CHANCES. && .UPDATE... ISSUED AT 638 AM EST WED JAN 2 2013 FORECAST GOING ALONG TO PLAN THIS MORNING WITH FLURRIES IN THE WESTERLY FLOW REGIMES...EXPANDED FROM INVADING WIDESPREAD LOW LEVEL STRATUS. THIS STRATUS HAS COVERED ALMOST EVERYONE (ALPENA WITHIN THE NEXT HOUR OR SO). THERE IS A LOSS OF CONFIDENCE IN THE DEVELOPMENT OF A PRETTY GOOD BAND OF SNOW OUT OVER LAKE HURON. THE DRAINAGE FLOW INTO THIS AREA...IS LAGGING BY A FEW HOURS. SO REMOVED THE HIGH CHANCES FOR SNOW...AND CERTAINLY FOR THE NE LOWER COAST. WILL HOLD ON TO SOME HOPE BY EARLY AFTERNOON...BUT NOT SO SURE ABOUT THAT EITHER. ALL OF NRN LOWER SHOULD MAINLY SEE FLURRIES...UNTIL LATER THIS AFTERNOON...WHEN INCREASING MOISTURE AND A SW FLOW MAY BRING A FEW TENTHS TO THE NW LOWER COAST. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 449 AM EST WED JAN 2 2013 WEAK HIGH PRESSURE WAS SETTLED IN OVER THE REGION...WITH MUCH COLDER AIR ACROSS ONTARIO DRAINING IN ACROSS EASTERN LAKE SUPERIOR...ENHANCING A LOW LEVEL COLD FRONT/CONVERGENCE. THIS CONVERGENCE AND AIR FLOW OVER LAKE SUPERIOR PRODUCED QUITE THE MODERATE/INTENSE SNOW BAND THAT FILTERED IN MAINLY JUST THE PARADISE AREA A FEW HOURS BACK. THIS BAND OF SNOW HAS WEAKENED OVER EASTERN UPPER DUE TO LOSS OF A DECENT FETCH. THE REST OF NRN MICHIGAN WAS SEEING A RAPIDLY APPROACHING STRATUS LAYER FROM LAKE MICHIGAN AND WISCONSIN...WITH A CONTINUED EXPECTATION TO SWEEP OVER ALL OF THE REGION. CLEAR SKIES IN SPOTS ACROSS FAR NRN LOWER AND NE LOWER WILL BECOME CLOUDY AGAIN. FLURRIES WERE STILL FAIRLY PREVALENT OUTSIDE OF THE CLEAR REGIONS...AND THE UPSTREAM CLOUDS ALSO CONTAIN FLURRIES. RADAR SHOWING THIS IS THE CASE...WITH NEW ECHOES POPPING UP OVER LAKE MICHIGAN. TEMPERATURES WERE IN THE TEENS AND LOWER 20S. NEXT ALBERTA CLIPPER WAS MOVING INTO FAR NRN MN WITH TROUGHING EXTENDING EASTWARD AND CONNECTING WITH THE ENHANCED TROUGHING FROM THE COLD AIR DRAINAGE/COLD FRONT. THE SYSTEM COLD FRONT WAS DRAPED THROUGH EASTERN ND/SD AND DOWN INTO NEBRASKA. DEEPER MOISTURE WAS SEEN VIA SATELLITE ALONG AND BEHIND THE COLD FRONT...AS WELL AROUND THE NRN PERIPHERY OF THE LOW PRESSURE. TODAY AND TONIGHT...WILL BE RAMPING FOR THE ARRIVAL OF THE CLIPPER LATE TONIGHT AND INTO THURSDAY. THE STRATUS FROM WISCONSIN WAS ERODING FROM THE SW...WITHIN WEAK WARM AIR ADVECTION INTO THE CLOUD LAYER. NOT WORRIED TOO MUCH ABOUT THIS WARM ADVECTION ERODING THE STRATUS FOR US...SINCE LOW LEVEL TEMPS OF -8C TO -10C HOLD THROUGHOUT THE DAY...SUFFICIENT COLD ENOUGH TO KEEP NOT ONLY CLOUDS IN PLACE...BUT TO ALSO ALLOW FOR THE CONTINUED GENERATION OF LAKE EFFECT FLURRIES. THESE FLURRIES WILL BE WITHIN WEST FLOW REGIMES THIS MORNING...THEN SW FLOW REGIMES AS WINDS BACK AHEAD OF THE APPROACHING LOW PRESSURE. ONE FLY IN THE OINTMENT THAT COULD HAVE SOME SIGNIFICANT RAMIFICATIONS IN THE SNOWFALL/AMOUNTS IS FOR THE DRAINAGE FLOW FROM ONTARIO...EXPECTED TO ENHANCE CONVERGENCE OVER LAKE HURON...WHICH COULD NEAR THE NE LOWER SHORELINE. HI RES MODELS/LATEST RUC ARE STEADFAST ON THIS IDEA BY DAYBREAK...WITH THE DEVELOPMENT OF ANOTHER MODERATE/INTENSE LAKE SNOW BAND. CONFIDENCE IN THIS ISN`T THE GREATEST...DUE IN PART TO THE DRAINAGE LAGGING THE HI RES TIMING (NOT EVEN INTO THE SAULT RIGHT NOW)...AND THAT MIXING INTO THE MORNING MIGHT KEEP THE CONVERGENCE WELL OUT INTO NRN LAKE HURON...NOT THREATENING OUR COASTAL AREAS. THIS IS SOMETHING TO KEEP A CLOSE EYE ON...AS THE ARRIVAL OF THE CONVERGENCE INTO FAR NRN LOWER AND EASTERN UPPER...WOULD ENHANCE CONVERGENCE AND RESULT IN STRONGER THAN EXPECTED SNOWS. AGAIN...NOT ENTIRELY SOLD ON THIS. DID INCREASE CHANCES FOR SEEING BONA FIDE SNOWS AND SMALL ACCUMULATIONS...BUT FEELING IS FOR ANY ACCUMS TO REMAIN UNDER AN INCH. WE WILL HAVE TO WAIT FOR INCREASED SW WINDS AND DEEPER MOISTURE AHEAD OF THE CLIPPER`S COLD FRONT. THIS HAPPENS THROUGH THE NIGHT...BUT MAINLY AFTER MIDNIGHT. INCREASED MOISTURE FLUX OFF THE LAKES WILL HELP...BUT INVERSION HEIGHTS RISING TO MAYBE 4500-5000FEET WITH DELTA T`S UNDER 15C...AND NO GOOD SUPPORT ALOFT WILL MORE LIKELY RESULT IN ACCUMULATIONS IN THE 1-2 INCH RANGE WITH A SLIVER OF AN AREA ACROSS CENTRAL CHIP/MACK COUNTIES...AND EMMET COUNTY SEEING UP TO 3 INCHES. IF THERE IS A LAKE HURON BAND OF SNOW THAT DEVELOP THIS MORNING...THE SW FLOW WILL GRADUALLY PUSH THIS SNOW IN ACROSS DRUMMOND ISLAND BEFORE DEPARTING EAST OF THERE. VERY DIFFICULT MESOSCALE FORECAST IN THE SHORT TERM. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 449 AM EST WED JAN 2 2013 ENERGETIC SPLIT FLOW PATTERN SET TO CONTINUE...WITH ONE LAST NORTHERN STREAM ORIGINATED SHORTWAVE SET TO VISIT OUR AREA LATER TONIGHT INTO THURSDAY. AFTERWARD...NORTHERN STREAM PROGGED TO RETREAT NORTH...BOTTLING UP THE ARCTIC COLD WELL TO OUR NORTH FOR THE FORESEEABLE FUTURE...PART OF A BURGEONING POSITIVE AO SIGNATURE AND EAST DISPLACED NORTH ATLANTIC BLOCKING. NOT TO SAY THE PATTERN DOESN`T HOLD AT LEAST SOME SNOW POTENTIAL FOR THE SNOW ENTHUSIASTS AMONGST US...WITH THURSDAY`S LEAD CHARGING SYSTEM HAVING THE LOOKS OF A RATHER SNEAKY LAKE ENHANCED SNOW EVENT FOR THE TRADITIONAL SNOWBELTS. TAKING A LOOK EVEN FURTHER OUT...MAY SEE THE BEGINNINGS OF THE INFAMOUS "JANUARY THAW" HEADING INTO NEXT WORK WEEK...WITH WELL AGREED UPON PROGS SUGGESTING A FURTHER RELAXATION OF THE NORTHERN STREAM AND A FLOODING OF MODIFIED PACIFIC AIR ACROSS THE CONUS. LARGE SCALE INDICES WOULD TEND TO AGREE...ALTHOUGH WITH DOMINATE POLAR VORTEX ON THIS SIDE OF THE GLOBE...HAVE SOME SUSPICION NORTHERN STREAM WILL NOT YIELD AS AGGRESSIVELY AS SOME PROGS WOULD SUGGEST. GETTING A TOUCH AHEAD OF MYSELF...AND STILL HAVE AMPLE CONCERNS IN THE SHORT TERM PORTION OF THE LONG TERM TO DEAL WITH...MOST NOTABLY THURSDAY`S SNOW POTENTIAL. DEFINITELY AN INTRIGUING SYSTEM FOR THURSDAY AS FAST MOVING AREA OF LOW PRESSURE SLICES ACROSS LAKE SUPERIOR EARLY...DRAGGING AN EQUALLY FAST MOVING COLD FRONT THROUGH NORTHERN MICHIGAN DURING THE MORNING. WHILE CORE OF BETTER MID LEVEL DYNAMICS LOOK TO PASS BY JUST TO OUR NORTH..STILL DECENT SLUG OF UPWARD QG SUPPORT ALONG SHARP SHORTWAVE TROUGH AXIS PASSING OVERHEAD. DEEP LAYER MOISTURE NOTHING TO WRITE HOME ABOUT...WITH PWAT VALUES STRUGGLING TO EXCEED A QUARTER OF AN INCH. STILL...WOULD EXPECT AT LEAST SOME SYNOPTIC DRIVEN SNOWS TO ACCOMPANY SHORTWAVE PASSAGE DURING THE MORNING. WILD CARD REMAINS LAKE ENHANCEMENT POTENTIAL...BOTH ALONG AND PROCEEDING COLD FRONTAL PASSAGE. PREFRONTAL AIRMASS MORE THAN COLD ENOUGH TO SUPPORT LAKE ENHANCED SNOWS...PARTICULARLY AS CONVERGENCE IS MAXIMIZED ALONG FRONTAL SLOPE. TEMPERATURES COOL FURTHER IMMEDIATELY BEHIND THE FRONT...WITH H85 READINGS APPROACHING THE NEGATIVE MIDDLE TEENS BY AFTERNOON. MOISTURE REMAINS ABUNDANT UNTIL MID LEVEL TROUGH PASSAGE DURING THE AFTERNOON...SUGGESTING AT LEAST A SEVERAL HOUR WINDOW OF GOOD LAKE ENHANCED SNOWS IN FAVORED WNW-NW FLOW AREAS THROUGH THE MORNING. MODEL DERIVED SOUNDING BEAR THIS POTENTIAL OUT (ESPECIALLY NAM-BUFR SOUNDINGS WHICH HAVE SOME SUPPORT FROM LATEST ECMWF PROGS)...WITH QUICK UPTICK TO NEAR H75 INVERSION LEVELS...ALL THE WHILE OMEGA MAX BECOMES CENTERED IN PRIME DGZ. HOW WILL ALL THIS PLAY OUT? KINDA ENVISION A PERIOD OF DECENT SNOWS ACROSS NORTHWEST LOWER/EASTERN UPPER MICHIGAN WITH THE FRONTAL PASSAGE...WITH A QUICK TRANSITION TO WNW-NW LAKE ENHANCED SNOWS THROUGH THE REMAINDER OF THE MORNING. ACTIVITY SHOULD BEGIN TO WIND DOWN RATHER QUICKLY DURING THE AFTERNOON...AND ESPECIALLY THURSDAY EVENING...AS MOISTURE RAPIDLY DEPARTS. CIPS ANALOGS FOR THIS EVENT HONING IN ON SOME INTERESTING NUMBERS...WITH IMPACT GUIDANCE SHOWING 6 TO 8 INCH AMOUNTS IN THE TRADITIONAL SNOWBELTS OF BOTH PENINSULAS. QUICK MOVEMENT OF SYSTEM AND SOME LINGERING CONCERN WITH EXACT THERMAL STRUCTURES (SOME GUIDANCE NOT QUITE AS COLD) PREVENTS FROM GOING THIS AGGRESSIVE...BUT WILL GO AHEAD A RAISE INHERITED SNOW AMOUNTS BY AT LEAST AN INCH OR SO...BRINGING DAYTIME ACCUMULATIONS TO 2 TO 3 INCHES IN FAVORED AREAS. IF TRENDS HOLD...MAY EVENTUALLY NEED AN ADVISORY FOR AT LEAST SOME COUNTIES OF NORTHWEST LOWER AND EASTERN UPPER MICHIGAN. SYSTEM EXITS JUST AS QUICK AS IT ARRIVES...WITH ANY LINGERING SNOW SHOWERS COMING TO AN END OVERNIGHT THURSDAY AS MOISTURE DEPARTS AND WAA COMMENCES. CONDITIONS LOOK QUIET AND A TOUCH WARMER TO END THE WORK WEEK AS THE NORTHERN STREAM RELAXATION BEGINS...LETTING HEIGHTS BUILD AND SOUTHWEST WINDS TO DEVELOP ON NORTH SIDE OF SOUTHERN HIGH PRESSURE. NEXT MOISTURE STARVED SYSTEM ARRIVES OVER THE WEEKEND...PERHAPS BRINGING A FEW SNOW SHOWERS ONCE AGAIN SATURDAY INTO SATURDAY NIGHT. TEMPERATURES APPEAR TOO MARGINAL FOR ANY PRE AND POST FRONTAL LAKE ENHANCEMENT. MAIN STORM TRACK CONTINUES TO TREND FURTHER NORTH HEADING INTO NEXT WORK WEEK. PACIFIC AIR STILL APPEARS RATHER AGGRESSIVE...WITH LATEST PROGS SUGGESTING MUCH OF THE NORTHERN CONUS FLOODED BY ABOVE NORMAL TEMPERATURES BY THE MIDDLE OF NEXT WEEK. FORECAST WILL REFLECT THE BEGINNING OF THIS WARM-UP...WITH READINGS RUNNING SEVERAL DEGREES ABOVE NORMAL BY MONDAY AND TUESDAY. AS MENTIONED EARLIER...NOT ENTIRELY SOLD YET ON THIS AGGRESSIVE WARMING...AND STILL PLAUSIBLE FOR BRIEF NORTHERN STREAM FORAYS TO KEEP THE BULK OF THE WARMING OFF TO OUR WEST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 638 AM EST WED JAN 2 2013 WIDESPREAD MVFR CIGS WILL BE COMMON FOR EVERYONE WITH FLURRIES AND NO VSBY RESTRICTIONS. CONFIDENCE IS FAIRLY HIGH HERE. THE MVFR CIGS WILL GO THROUGH THE NIGHT...ACTUALLY LOWER TO POSSIBLE IFR LATE TONIGHT WHEN DEEPER MOISTURE AND INCREASING ACTIVE LAKE EFFECT AND A SLIGHTLY MORE WESTERLY WIND BRINGS IN SOME BETTER SNOWS. WINDS WILL BE WESTERLY BACKING MORE SW WITH TIME...BUT 10KTS OR LESS. && .MARINE... ISSUED AT 449 AM EST WED JAN 2 2013 WINDS WILL GRADUALLY WEAKEN TODAY...BEFORE PICKING BACK UP AGAIN TONIGHT...IN ADVANCE OF AN ALBERTA CLIPPER AND ASSOCIATED COLD FRONT. THE TIGHTEST GRADIENT WILL RESIDE ACROSS THE NW LOWER NEARSHORE...THROUGH THE STRAITS AND INTO NRN LAKE HURON. OVERLAKE INSTABILITY WILL BE DEEPENING WITH THE ABILITY TO TAP ADVISORY LEVEL GUSTS IN THESE AREAS. IN ADDITION...THIS DEEPENING INSTABILITY...AND DEEPER MOISTURE FROM THE CLIPPER...WILL RESULT IN ENHANCED LAKE EFFECT SNOW SHOWERS. THE WINDS WILL BE STRONGEST BEHIND THE COLD FRONT...THURSDAY THROUGH FRIDAY...AND THESE ADVISORIES WILL NOT ONLY NEED TO BE EXTENDED...BUT THE REMAINDER OF THE NEARSHORE WATERS WILL LIKELY NEED ADVISORIES TOO. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR LHZ345>349. LM...SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR LMZ323-342- 344>346. LS...NONE. && $$ UPDATE...SD SYNOPSIS...MB SHORT TERM...SD LONG TERM...MB AVIATION...SD MARINE...SD
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
611 AM CST WED JAN 2 2013 .UPDATE...FOR 12Z AVIATION DISCUSSION BELOW && .DISCUSSION.../ISSUED 227 AM CST WED JAN 2 2013/ MAIN FORECAST CONCERN IS WHETHER THERE IS ENOUGH ENERGY TO GENERATE LIGHT SNOW ACROSS THE FA THIS MORNING...AND INTO EARLY THIS EVENING. WEAK AND UNORGANIZED RETURNS FROM REGIONAL RADAR AND THE LACK OF ANY COOLING OR ENHANCEMENT OF UPSTREAM CLDS...HAS ME WONDER IF LIKELY POPS ARE TOO HIGH FOR TODAY...ESPECIALLY CONSIDERING THE SFC LOW WILL BE WELL NORTH OF OUR FA...AND DEEPER MOISTURE RESIDES BEHIND THE MAIN FRONTAL BOUNDARY ACROSS THE EASTERN DAKOTAS. IN ADDITION...SOME OF THE LOCAL WRF MODELS REFLECTIVITY IMAGERY HAS ALMOST LITTLE RETURNS OR NOTHING HIGHER THAN 15 DBZ...AND MAINLY FOR WC/CENTRAL MN BEFORE 18Z. THIS SEEMS TO BE REASONABLE BASED ON THE LATEST REGIONAL RADAR RETURNS ACROSS THE EASTERN DAKOTAS. BUT UNDER THE WEAK RETURNS...NEARLY NO RESTRICTIONS TO VSBY IN -SN WAS NOTED. THE ONLY CONTINUATION FOR THE LIKELY POPS IS DEEPER MOISTURE BEHIND THE FRONT ALONG THE -15C ZONE...AND A SLIGHT INCREASE IN PVA WHICH MAY ENHANCE OUR REGION LATER THIS AFTN/EARLY EVENING. EVEN WITH THE LIKELY POPS...QPF AMTS WILL BE VERY LOW AND UNDER 0.03 WHICH LEADS TO A DUSTING OR UP TO AN HALF INCH IN SOME LOCATIONS ACROSS WEST-CENTRAL AND CENTRAL MN THIS MORNING. AFTER TONIGHT...NO FORECAST CONCERNS AS THE MEAN PATTERN BECOMES QUIET FOR OUR REGION WITH THE MAIN STORM TRACK WELL NORTH AND SOUTH OF THE FA. AS MORE PACIFIC TYPE AIR MASSES BEGIN TO SPILL OVER THE ROCKIES...AND INTO THE NORTHERN PLAINS/UPPER MIDWEST...EXPECT OUR REGION TO BEGIN TO MODIFY IN TERMS OF TEMPS WITH NEAR FREEZING HIGHS ON FRIDAY...AND NEXT WEEK. BOTH THE EC/GFS HAVE A SPLIT FLOW TYPE OF UPPER AIR PATTERN WHICH WILL LIKELY BE CHAOTIC WITH EACH RUN PAST FIVE DAYS. THERE IS SOME SIGNS OF A STORM DEVELOPING ACROSS THE SOUTHERN U.S. LATE NEXT WEEK...WHICH MAY BEGIN TO AFFECT OUR REGION BY THE WEEKEND OF THE 12TH. THE CURRENT RUN OF THE NAEFS AND CFS CLIMATE MODEL DOES SUPPORT THE ABOVE NORMAL TEMPS NEXT WEEK. HOWEVER...THERE HAS BEEN A TREND TO COOL THINGS DOWN AGAIN BY THE THIRD AND FOURTH WEEK OF JANUARY. ALSO LOOKING AT THE CFSV2 FORECAST OF MONTHLY CLIMATE ANOMALIES FOR FEBRUARY DOES HAVE A STRONG SIGNAL OF COLDER AND WETTER PATTERN DEVELOPING. TIME WILL TELL! ..JLT.. && .AVIATION.../12Z TAF ISSUANCE/ WIDESPREAD IFR/MVFR CONDITIONS WILL OCCUR TODAY AHEAD OF THE SFC LOW THAT WAS CENTERED OVER THE NWRN CORNER OF MN AT 12Z. WHILE A CLEAR SLOT DEVELOPED OVER WEST/SOUTH CENTRAL MN OVERNIGHT...EXPECT THIS TO FILL BACK IN OVER THE NEXT FEW HOURS AS THE LOW BEGINS TO SINK SOUTHEAST ACROSS NORTHERN/CENTRAL MN. THE OTHER NEAR-TERM CONCERN IS FOG...AS EXHIBITED BY VSBYS IN THE 1SM-3SM RANGE OVER SOUTH CENTRAL MN. THIS POCKET OF REDUCED VSBYS IS BEING ANALYZED FAIRLY WELL BY THE RAP AND HRRR MODELS...WHICH PROG THE AREA OF REDUCED VSBYS TO ADVECT NORTHWARD THIS MORNING. THINK VSBYS WILL OCCASIONALLY DIP TO IFR BETWEEN 12Z AND 17Z IN CENTRAL/EAST CENTRAL MN. SNOW ASSOCIATED WITH THE AFOREMENTIONED LOW WILL BEGIN AT AXN SHORTLY AFTER THE TAF PERIOD BEGINS AND REACH KSTC/KRWF BY LATE MORNING. KMSP SHOULD SEE LIGHT SNOW BY 20Z...AND KRNH/KEAU BY 22Z. PREVALENT MVFR VSBYS ARE EXPECTED TO ACCOMPANY THE LIGHT SNOW...WITH TEMPORARY IFR VSYBS TO AROUND 2SM THE MOST POSSIBLE AT WESTERN SITES /KAXN AND KRWF/. THE SNOW SHOULD TAPER OFF THIS EVENING...ALTHOUGH MVFR CIGS WILL LIKELY PERSIST INTO THURSDAY. NORTHWEST WINDS ARE EXPECTED TO GUST INTO THE MID/UPPER TEENS /KNOTS/ IN THE WAKE OF THE FRONT. KMSP...POCKET OF FOG WITH VSBYS OF 1-3SM AND CIGS AROUND 500 FT WILL PLAGUE KMSP THIS MORNING. VSBYS SHOULD IMPROVE TO AROUND 5SM BY THIS AFTERNOON...WITH -SN EXPECTED TO BEGIN AROUND 20Z AS THE FRONT ARRIVES. WINDS SHOULD SHIFT TO NORTHWEST AFTER 00Z...WITH GUSTS TO AROUND 17KTS POSSIBLE TONIGHT. SHOULD SEE GRADUAL IMPROVEMENT IN CIGS TONIGHT...ALTHOUGH WILL LIKELY NOT CLEAR OUT THE OVC 3KFT DECK. /OUTLOOK FOR KMSP/ THU...VFR. WINDS NW AT 10G15KTS. FRI...VFR. WINDS SW AT 5 TO 10KTS. SAT...VFR WITH MVFR CIGS AND -SN POSSIBLE. WINDS NW AT 5 TO 15KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JLT/LS
AREA FORECAST DISCUSSION...UPDATED
NWS GLASGOW MT
924 AM MST WED JAN 2 2013 .SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH FRIDAY... A LARGE-SCALE UPPER LEVEL RIDGE BUILDING UP OVER THE WEST WILL PUSH THE REMNANTS OF THE TROUGH TO THE EAST TODAY. SNOW SHOWERS ARE STILL SHOWING UP THIS MORNING ON THE RADAR...MAINLY EAST OF GGW. ADJUSTED POPS ACCORDINGLY WITH LOW QPF. OTHERWISE SPREAD OVERCAST SKIES TO THE WEST FOR THIS MORNING BASED ON WR FOG/REFL PRODUCT. A STRONG SURFACE TROUGH LOCATED OVER NORTH DAKOTA WILL MAINTAIN GUSTY WINDS TODAY. HOWEVER AS THE TROUGH MOVES FARTHER EAST...THE NW WIND WILL DIMINISH IN STRENGTH FROM THE WEST. UPDATED WINDS WITH LATEST GUIDANCE. SCT PREVIOUS DISCUSSION... A DIFFICULT BEGINNING TO THE FORECAST THIS MORNING ACROSS NORTHEAST MONTANA. A FEW SNOW SHOWERS ARE FLOATING AROUND THE SOUTHERN ZONES...BUT UPSTREAM FAIRLY CLEAR VIA THE IR SAT THIS MORNING. BETHUNE AND SCHULER RADARS TO OUR NORTH HAVE THE SNOW SHOWERS MAINLY EAST OF ASSININBOIA THIS MORNING TRACKING SOUTHEAST. WILL KEEP THE HIGHER POPS ALONG THE NORTH DAKOTA BORDER EVEN THOUGH CONFIDENCE IS FALLING OFF QUICKLY WITH THE NAM/GFS AS PER THE HRRR WHICH KEEPS THE AREA DRY THROUGH THE MORNING HOURS. IF THE EAST STARTS TO CLEAR MIGHT HAVE TO MAKE AN EARLY MORNING UPDATE TO IMPROVE THE WEATHER IN THE EAST TODAY. BY TONIGHT THE RIDGE BUILDS IN...AS PER ALL GUIDANCE PRODUCTS WHICH WILL DRY THE AREA OUT ABOVE 2700 FEET IN THE ATMOSPHERE AND BEGIN TO WARM IT UP AT THE HIGHER ELEVATIONS. THE LOWER ELEVATIONS WILL STAY BELOW THE INVERSION AND IN THE SHALLOW COLD AIR WILL LOOKS TO HANG ON UNTIL FRIDAY. MAKES FOR A DIFFICULT TEMPERATURE FORECAST... ABOVE 3000 FEET 30S AND 40S LOOK GOOD... BELOW 2500 SORRY BUT LOOKS FOR THE TEENS AND 20S WITH OVERNIGHT LOWS IN THE SINGLE DIGITS. ITS THE IN BETWEEN THOSE TWO ELEVATIONS THAT WILL BOUNCE AROUND. FRIDAY THE RIDGE GETS FLATTENED BY A DRY SHORTWAVE WHICH SHOULD ALLOW MIXING DOWN INTO THE VALLEYS AND ALLOW THE VALLEY BOTTOM LOCATIONS TO ENJOY A LITTLE WARMER AIR... CHINOOK WINDS SHOULD KICK UP IN THE WESTERN ZONES AND HIGHER ELEVATIONS IN THE EAST WITH ABOVE NORMAL TEMPERATURES TO FINISH THE SHORT TERM OF THE FORECAST. PROTON .LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...THERE HAS NOT BEEN MUCH CHANGE IN THE THINKING AS FAR AS THE EXTENDED IS CONCERNED. AN UPPER RIDGE BUILDS INTO THE FORECAST AREA ON SATURDAY WHICH WILL LEAD TO MOSTLY SUNNY SKIES AND DRY CONDITIONS. SATURDAY NIGHT UNDER MAINLY CLEAR SKIES IF WINDS BECOME LIGHT THERE COULD BE THE POTENTIAL FOR THE FORMATION OF FREEZING FOG. THE 00Z ECMWF BRINGS IN THE NEXT SHORTWAVE FOR SUNDAY AFTERNOON AND SO THAT SHOULD HELP TO MIX OUT ANY FOG THAT DOES DEVELOP. THE 00Z GFS TAKES THIS WAVE FURTHER TO THE NORTH...KEEPING THE CWA IN NORTHWEST FLOW ALOFT. REGARDLESS...MODEL GUIDANCE IS DRY FOR THE PERIOD SO DID NOT INSERT A MENTION OF POPS WITH THIS WAVE. THE ECMWF BRINGS YET ANOTHER UPPER WAVE THROUGH THE AREA ON MONDAY AFTERNOON AND THE GFS AGAIN TRACKS IT TO THE NORTH. ONCE AGAIN DO NOT EXPECT MUCH PRECIPITATION TO RESULT. TUESDAY AND BEYOND...TOWARDS THE MIDDLE OF THE WEEK MODELS ARE CONVERGING ON THE IDEA OF THE WESTERN HALF OF THE U.S. BEING DOMINATED BY SPLIT FLOW ALOFT. THIS PLACES NORTHEAST MONTANA UNDER THE INFLUENCE OF AN UPPER RIDGE ASSOCIATED WITH THE DRIER NORTHERN BRANCH. THUS...HAVE MODERATING TEMPERATURES IN THE GRIDS THROUGH THE MIDDLE OF NEXT WEEK. MID 40S FOR HIGHS SEEM LIKE A REAL POSSIBILITY IN SOME LOCATIONS IN PHILLIPS AND PETROLEUM COUNTIES AS WELL AS PARTS OF WESTERN GARFIELD COUNTY AS THE ECMWF WARMS 850MB TEMPERATURES AS HIGH AS +8C BY TUESDAY AFTERNOON. WENT AHEAD AND PUT IN SLIGHT CHANCE POPS ACROSS THE ENTIRE CWA FOR WEDNESDAY INTO THURSDAY AS LONG RANGE MODELS ARE IN AGREEMENT THAT A VIGOROUS SHORTWAVE WILL TRANSLATE ACROSS NORTHEAST MONTANA SOMETIME DURING THIS PERIOD. NOT TOO CONFIDENT THIS FAR OUT BUT FELT IT DID WARRENT A MENTION SINCE THERE IS DECENT MODEL AGREEMENT. MALIAWCO && .AVIATION... A SHORTWAVE TROUGH EXITS THE REGION DURING THE DAYTIME HOURS AS A RIDGE BUILDS IN FROM THE WEST. THIS WILL PUT AN END TO ANY ISOLATED TO SCATTERED SNOW SHOWERS IN THE VICINITY IN THE MORNING. ANY MVFR OR IFR CEILINGS WILL ALSO BEGIN TO LIFT AS SKIES CLEAR THROUGHOUT THE DAY. THUS...ANTICIPATING A RETURN TO VFR BY THE LATE MORNING OR AFTERNOON. EXPECT WEST TO NORTHWEST SURFACE WINDS DURING THE DAY RANGING FROM 10-20 KTS. MALIAWCO && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
643 AM EST WED JAN 2 2013 .SYNOPSIS... A COLD FRONT MOVING THROUGH LATE TODAY WILL USHER IN SOME DRIER AIR SHUTTING OFF THE RAIN ALTHOUGH CLOUDS WILL TEND TO LINGER. A WAVE OF LOW PRESSURE ALONG THE FRONT AS IT SITS OFF THE COAST WILL FINALLY ALLOW SOME CLEARING THURSDAY NIGHT. HIGH PRESSURE WILL BUILD IN FROM THE WEST OVER THE WEEKEND FOLLOWED BY A RAIN-FREE COLD FRONT ON SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM WEDNESDAY...THE FRONT APPEARS TO BE DROPPING SOUTH A LITTLE FASTER THAN EARLIER MODELS INDICATED. THE RUC HAS THE BEST NEAR-TERM INITIALIZATION AND IS THE BASIS FOR UPDATES OVER THE NEXT 8 HOURS. WINDS HAVE SHIFTED TO THE NORTH AT WILMINGTON... WHITEVILLE...GREEN SEA...MARION AND FLORENCE. THE WIND SHIFT SHOULD REACH THE MYRTLE BEACH AREA VERY SOON...AND GEORGETOWN BY 9-10 AM. A NARROW RIBBON OF WARM AIR ALONG THE SC COAST (STILL 61 IN GEORGETOWN AND 63 IN MYRTLE BEACH) WILL BE SWEPT OUT TO SEA BY THE FRONT WITH FALLING TEMPERATURES EXPECTED LATER THIS MORNING. FOR AREAS WHERE THE FRONT HAS ALREADY PASSED...TEMPERATURES SHOULD CONTINUE FOR THE NEXT FEW HOURS AS COOL AIR BLEEDS IN FROM THE NORTH. ONCE PRECIPITATION ENDS TEMPERATURE CURVES WILL TURN UPWARDS SLIGHTLY DURING THE MID AFTERNOON BUT EVEN THEN WE ARE ONLY TALKING A FEW DEGREES RISE WITH CONSIDERABLE CLOUD COVER REMAINING. ONE LAST BATCH OF LIGHT RAIN OVER CENTRAL SOUTH CAROLINA SHOULD NOT INTENSIFY AS IT STREAKS EAST TO THE COAST OVER THE NEXT 3-4 HOURS. BEHIND IT...CLOUDS WILL REMAIN BUT THE IMPETUS FOR ADDITIONAL PRECIP APPEARS MISSING WITH THE SUBTROPICAL JET STREAK MOVING OFF THE NORTHEAST U.S. COAST. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... A WEAK AREA OF LOW PRESSURE IS CROSSING THE EASTERN CAROLINAS... FOLLOWING A SLOW MOVING COLD FRONT THAT IS DROPPING SOUTHWARD TOWARD THE COAST. THIS FRONT IS BECOMING A LITTLE EASIER TO FIND IN SURFACE OBSERVATIONS...OUTLINED BY A SHIFT TO NORTH WINDS ACROSS CENTRAL NORTH CAROLINA INTO NORTHWESTERN SOUTH CAROLINA. A BROAD STRIPE OF LIGHT TO MODERATE RAINFALL NEAR AND NORTH OF THE FRONT IS BEING PRODUCED MAINLY THROUGH JET DYNAMICS AS THE CAROLINAS ARE WITHIN THE RIGHT-ENTRANCE REGION OF A STRONG JET STREAK ACROSS THE NORTHEASTERN STATES. AS THIS JET STREAK PUSHES FARTHER OFFSHORE AFTER DAYBREAK THE RAIN HERE IN THE CAROLINAS SHOULD GRADUALLY DIMINISH IN INTENSITY AND COVERAGE. HIGH TEMPERATURES TODAY ARE GOING TO BE A TOUGH CALL PARTICULARLY ALONG THE SOUTH CAROLINA COAST AS THE FRONT MAY STILL BE TO THE NORTH AT 12Z/7 AM EST. A WARM SOUTHWEST WIND AHEAD OF THE FRONT MAY KEEP GEORGETOWN IN THE LOWER 60S UP UNTIL THE FRONT ARRIVES...WITH UPPER 50S POSSIBLE IN MYRTLE BEACH. BEHIND THE FRONT TEMPERATURES SHOULD FALL INTO THE LOWER TO MID 50S ALONG THE SC COAST WITH LITTLE CHANGE REST OF THE DAY. FARTHER NORTH TODAY`S HIGH TEMPERATURE FORECAST IS A LITTLE MORE CERTAIN WITH A NEARLY STEADY 53-55 EXPECTED FOR MOST AREAS. SKIES SHOULD REMAIN OVERCAST MUCH OF THE DAY. THE FRONT WILL STALL ACROSS NORTH FLORIDA AND THE GEORGIA OFFSHORE WATERS TONIGHT. LOW PRESSURE WILL DEVELOP ALONG THIS FRONT LATE TONIGHT WHICH MAY LEAD TO RENEWED DEVELOPMENT OF LIGHT RAIN MAINLY ALONG THE COAST. WITH CONTINUED LOW-LEVEL COLD ADVECTION LOWS TONIGHT SHOULD FALL TO THE UPPER 30S OVER INTERIOR SOUTHEASTERN NORTH CAROLINA TO THE LOWER 40S ELSEWHERE. && .SHORT TERM/THURSDAY THROUGH FRIDAY NIGHT/... AS OF 3 AM WEDNESDAY...A BROAD SWATH OF WEST-SOUTHWESTERLY MID LEVEL FLOW WILL BE STREAMING ACROSS THE SOUTHEAST ON THURSDAY. EMBEDDED WITHIN THIS FLOW WILL BE A WEAK SHORTWAVE THAT WILL SPIN UP A SMALL AREA OF LOW PRESSURE ALONG THE WELL-OFFSHORE FRONTAL BOUNDARY. THIS COULD SPREAD SOME VERY LIGHT RAINFALL ALONG THE IMMEDIATE COAST WHEREAS AREAS FURTHER INLAND WILL SEE PLENTY OF CLOUDS BUT TEND TO STAY RAIN FREE. IN THE WAKE OF THIS SYSTEM SOME DRY AIR WILL MANAGE TO PUSH IN FROM THE NORTHWEST THURSDAY NIGHT BRINGING CLEARING SKIES. IT WILL ALSO BRING SOME LOW LEVEL COLD AIR ADVECTION KEEPING FRIDAY AFTERNOON A FEW DEGREES ON THE CHILLY SIDE OF NORMAL DESPITE THE RETURN OF SUNSHINE. HIGH PRESSURE REMAINING TO OUR WEST FRIDAY NIGHT WILL MAINTAIN A FEW MPH OF NORTHERLY WINDS AND PREVENT IDEAL RADIATIONAL COOLING OTHERWISE SUPPORTED BY THE MINIMAL CLOUD COVER. THERE WILL ALSO BE SOME WARM ADVECTION JUST GETTING UNDERWAY OVER SOUTHERN ZONES THE LAST FEW HOURS OF THE PERIOD. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 3 AM WEDNESDAY...WEAKENING HIGH PRESSURE MOVES ACROSS THE AREA OVER THE WEEKEND KEEPING CLOUD COVER FAIRLY MINIMAL AND TEMPERATURES FAIRLY CLOSE TO SEASONABLE NORMS. SUNDAY INTO MONDAY WILL SEE AN UPPER TROUGH SHARPENING ACROSS THE GREAT LAKES DRIVING A COLD FRONT SOUTH AND EAST. MOISTURE FLUX AHEAD OF THIS BOUNDARY WILL BE NEARLY NIL SO ITS ABILITY TO PRODUCE RAINFALL IN THE EAST JUST ABOUT THE SAME. THIS BOUNDARY WILL MOVE TROUGH LATER SUNDAY. MONDAY WILL SEE HIGH PRESSURE MOVE IN FROM THE NW. TOUGH CALL ON TEMPS MONDAY AS THE THERMAL TROUGH BEHIND THE COLD FRONT IS SO NARROW THAT WARM ADVECTION BACK UNDERWAY BY AFTERNOON. IT MAY END UP BEING QUITE SEASONABLE. THIS WAA SHOULD THEN TRANSLATE TO A MILDER TUESDAY. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... AS OF 12Z...MVFR/IFR DUE TO LOWERED CIGS AND VISIBILITIES ARE SPREADING ACROSS THE ENTIRE AREA THIS MORNING AS A FRONT SITUATED JUST INLAND FROM THE COAST CONTINUES TO SLOWLY PUSH ITS WAY TOWARDS THE COAST. CURRENT RADAR IMAGERY DEPICTS A FEW LIGHT SHOWERS ACROSS THE FA WHICH WILL TAPER OFF WITHIN THE NEXT HOUR OR TWO...LEAVING BEHIND MVFR/IFR DUE TO LOWERED CIGS THROUGH LATE MORNING. LIGHT NORTH WINDS THIS MORNING WILL INCREASE TO AOB 8 KTS BY THIS AFTERNOON. MODELS ARE IN A BIT OF A DISAGREEMENT AS TO WHEN THESE CIGS WILL LIFT TO VFR...BUT GIVEN TIME-HEIGHT ANALYSIS AND FCST SOUNDINGS HAVE INTRODUCED VFR FOR THIS AFTERNOON WITH SCT/BKN MID TO HIGH-LEVEL CLOUDS. OVERNIGHT AND INTO THE MORNING HOURS...THE RETURN OF LOW CLOUDS MAY CREATE SUB-VFR CONDITIONS ONCE AGAIN...BUT GIVEN LOWERED CONFIDENCE ATTM...HAVE NOT INTRODUCED ANY RESTRICTIONS AS OF YET. NORTH-NORTHEAST WINDS WILL CONTINUE THROUGH THE PERIOD WITH SUSTAINED WINDS AOB 8 KTS. EXTENDED OUTLOOK...CHANCE FOR RAIN AND PERIODS OF SUB-VFR CONDITIONS THROUGH LATE THURSDAY ASSOCIATED WITH A NEARLY STATIONARY FRONT. VFR WILL DEVELOP FRIDAY AND PERSIST THROUGH THE REMAINDER OF THE PERIOD. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM WEDNESDAY...THE FRONT IS COMING THROUGH JUST A BIT FASTER THAN EARLIER THOUGHT...ESPECIALLY INLAND WHERE WINDS HAVE ALREADY TURNED NORTH AS FAR DOWN AS FLORENCE. AT THE BEACHES THE FRONT IS JUST NOW PASSING MASONBORO ISLAND. THE RUC MODEL APPEARS TO HAVE THE BEST HANDLE ON CURRENT CONDITIONS AND IS THE BASIS FOR WIND AND WEATHER UPDATES OVER THE NEXT 6-8 HOURS. WINDS ARE STILL EXPECTED TO INCREASE TO 15-20 KNOTS LATER THIS MORNING ACROSS THE NC WATERS...WITH THIS SURGE MAKING IT INTO THE SC COASTAL WATERS AROUND OR SHORTLY AFTER NOON. WE SHOULD REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA TODAY FOR WINDS AND SEAS. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... A COLD FRONT IS MAKING ITS WAY SOUTH ACROSS EASTERN NORTH CAROLINA AND SHOULD CROSS OUR AREA LATER THIS MORNING. BASED ON SURFACE OBSERVATIONS AND MODEL DATA THE FRONT SHOULD PASS CAPE FEAR BY 8 AM...MYRTLE BEACH BY 10 AM...AND GEORGETOWN BEFORE NOON. RAIN MAY ACCOMPANY THE FRONT...ESPECIALLY ACROSS THE NC WATERS. CONDITIONS SHOULD DRY OUT THIS AFTERNOON AS NORTHERLY WINDS SURGE ACROSS THE AREA BEHIND THE FRONT. THE FRONT WILL STALL ACROSS NORTHERN FLORIDA AND THE GEORGIA OFFSHORE WATERS TONIGHT AS LOW PRESSURE DEVELOPS ALONG IT. THIS DEVELOPMENT COULD SPREAD SOME RAIN BACK INTO THE AREA AFTER MIDNIGHT. SHORT TERM/THURSDAY THROUGH FRIDAY NIGHT/... AS OF 3 AM WEDNESDAY...NE WINDS TO START WITH A WEAK HIGH TO OUR N WILL BACK/CHANGE IN A COUNTERCLOCKWISE FASHION AS THE DAY WEARS ON AS A FAIRLY FLAT LOW MOVES BY WELL OFFSHORE. LOCAL SWAN BUILDS SEAS WITH ITS PASSAGE...TO THE TUNE OF 4 FT ALONG THE 20NM BORDER. AS IT PULLS AWAY THURSDAY NIGHT A BROAD HIGH WILL BUILD ACROSS MUCH OF THE SOUTHERN U.S. CENTERED OVER TX. MODERATE NORTHERLY WINDS WILL HELP TO PUSH HIGHER SEAS OUT OF THE FCST ZONES EVEN AS OVERALL WAVE HEIGHTS DIMINISH SLOWLY ANYWAY. WAVE SHADOWING ALSO KEEPING NEAR SHORE WAVES FAIRLY SMALL. WIND REMAINS OUT OF THE N OR NW FOR THE REST OF THE PERIOD AS THE HIGH DRAWS A LITTLE CLOSER. THE APPROACH OF THE HIGH WILL ALSO EASE THE GRADIENT AND WIND SPEED WILL DROP A FEW KNOTS. THE EFFECT ON SEAS WILL BE SMALL...PERHAPS CHANGING A 2 TO 3 FT FORECAST TO 2 FT. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 3 AM WEDNESDAY...HIGH PRESSURE BUILDS IN FROM THE WEST ON SATURDAY BUT IN A WEAKENING STATE. WINDS THROUGH THE DAY WILL BE VERY LIGHT AND MAY SHOW CONSIDERABLE VARIABILITY IN DIRECTION. LATE IN THE DAY OR AT NIGHT A PREDOMINANTLY WESTERN WIND WILL DEVELOP AS ANOTHER HIGH CENTER SETTLES OVER THE SOUTHERN U.S. A RAIN-FREE COLD FRONT MOVES IN FROM THE NORTHWEST ON SUNDAY BOLSTERING WIND SPEEDS ABOUT A CATEGORY INTO THE 10 TO 15 KT RANGE. SEAS SHOULD BUILD BACK INTO THE 2 TO 3 FT RANGE FROM THE QUIETER 2 FT FORECAST SEEN SATURDAY ACROSS MOST ZONES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...MBB NEAR TERM...TRA SHORT TERM...MBB LONG TERM...MBB AVIATION...SGL
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
942 AM CST WED JAN 2 2013 .DISCUSSION... A QUICK UPDATE...LIGHT RAIN STILL FALLING OVER THE COASTAL COUNTIES BUT IS LIGHT AND SOME SPRINKLES IN THE NEXT TIER OF COUNTIES INLAND. MOIST AXIS OVERRUNNING THE COLD DOME WILL BE SHIFTING EAST THROUGH THE AFTERNOON AND RAIN CHANCES WILL LIKELY LOWER THROUGHOUT THE AFTERNOON FROM NORTHWEST TO SOUTHEAST. RAIN COOLING SHOULD LESSEN AS WELL LATE IN THE AFTERNOON BUT HAVE LOWERED TEMPERATURES A FEW DEGREES FOR THE COOLING. SKIES SHOULD REMAIN CLOUDY MOST OF THE AFTERNOON IN THE EAST THEN IMPROVE AS DRIER AIR ALOFT SPREADS INTO THE REGION. WITH A QUICK DIP IN TEMPERATURES IN THE EVENING MAY NEED TO LOWER OVERNIGHT LOWS A DEGREE OR TWO AS WELL BUT WILL WAIT TO GET A LOOK AT THE LATER GUIDANCE BEFORE CHANGING THE MINS. 45 && .PREV DISCUSSION... /ISSUED 512 AM CST WED JAN 2 2013/ DISCUSSION... SEE 12Z AVIATION DISCUSSION. AVIATION... NAM/GFS FCST SOUNDINGS SHOW MVFR CIGS MIXING OUT BY 15Z WHILE THE RAP KEEPS CIGS IN PLACE THROUGH 18Z. THOUGHT THE RAP MIGHT HAVE A BETTER HANDLE ON THINGS BUT LATEST OBS SHOW MVFR CIGS SCATTERING OUT. FEEL VFR CONDS WILL DEVELOP BY AFTN BUT TIMING STILL A LITTLE IFFY. WINDS WILL BE LIGHTER THAN YESTERDAY ALTHO BRIEFLY HIGHER FOR A FEW HOURS AT KGLS EARLY THIS MORNING. RADAR SHOWS WIDESPREAD LIGHT RAIN BUT OBSERVATION SITES NOT REPORTING RAIN SO IT IS LIKELY VIRGA. WILL NOT BE CARRYING ANY MENTION OF PRECIP IN THIS SET OF TAFS. 43 PREV DISCUSSION... /ISSUED 341 AM CST WED JAN 2 2013/ DISCUSSION... BASED ON SFC OBS AND IR SATELLITE IMAGERY IT LOOKS LIKE THERE ARE SEVERAL LAYERS OF CLOUDS WITH LOW MVFR OVC CLOUD DECK BEING THE MOST PROMINENT. AREA RADAR ARE PICKING UP SOME LIGHT RETURNS FROM MID AND HIGH LEVEL CLOUDS BUT NOTHING HITTING THE GROUND GIVEN DRY AIR BELOW 700MB. PRECIP REMAINS CONFINED THE OFFSHORE WATERS OF THE UPPER TX COAST. SFC ANALYSIS HAS WEAK HIGH PRESSURE OVER THE S PLAINS WHICH SHOULD KEEP MODERATE NORTHERLY WINDS IN PLACE TODAY. CLOUD COVER AND WINDS SHOULD HOLD TEMPS IN THE 40S FOR MUCH OF THE DAY WITH MAX TEMPS POSSIBLY REACHING 50 IN A FEW SPOTS. CLOUD COVER WILL BE SLOW TO ERODE GIVEN WESTERLY JET STREAM FLOW. COUPLE OF SHORT WAVE TROUGHS ROTATING THROUGH A MEAN TROUGH OVER THE PLAINS AND C ROCKIES AND THEN A CLOSED LOW OFF THE CALIFORNIA COAST WILL MAINTAIN STRONG WESTERLY FLOW ALOFT THROUGH THE END OF THE WEEK. GIVEN CONTINUED CLOUD COVER AND WEAK NORTHERLY FLOW...WILL KEEP TEMPS A COUPLE OF DEGREES BELOW NORMAL FOR THE REST OF THE WEEK. BY FRIDAY MODELS ARE IN PRETTY GOOD AGREEMENT WITH UPPER LOW OVER S ROCKIES. MODELS THEN BEGIN TO MOVE THIS LOW INTO W TX BY SAT MORNING WITH SOME VORTICITY SHEARING OUT ACROSS THE PLAINS. GFS SEEMS TO BE A BIT FAST WITH STRETCHING OUT THE TROUGH WHILE ECMWF/NAM HAVE A BIT MORE PRONOUNCED TROUGH. MODELS KEEP BULK OF LARGE SCALE ASCENT NORTH OF SE TX BUT STILL ENOUGH FORCING TO TRIGGER SOME RAIN FOR SATURDAY. WILL KEEP 20 POPS IN THE FORECAST FOR RAIN BUT A LOT OF THIS DEPENDS ON HOW STRONG ISENTROPIC LIFT DEVELOPS AND IF ATMOSPHERIC COLUMN MOISTENS ENOUGH. NAM BUFR SOUNDINGS SHOW SOME MOIST PROFILES BY 06-12Z SAT WHICH WOULD SUPPORT RAIN. HIGH PRESSURE BUILDS BACK OVER TX FOR EARLY NEXT WEEK. LOOKS LIKE SOUTHERLY RETURN FLOW DOES NOT SET UP UNTIL TUE/WED NEXT WEEK IN THE FAR EXTENDED FORECAST. UNTIL THEN TEMPS WILL BE VERY CLOSE TO CLIMO NORMS. 39 MARINE... HIGH PRESSURE BUILDING INTO THE SOUTHERN PLAINS WILL MAINTAIN A TIGHT PRESSURE GRADIENT THROUGH THE END OF THE WEEK. A MODERATE NORTH TO NORTHEAST FLOW IS EXPECTED TO PERSIST THROUGH THE END OF THE WEEK. WINDS WILL GENERALLY STAY NEAR OR JUST BELOW SCA CRITERIA THROUGH TONIGHT AND THEN BRIEFLY INCREASE AGAIN ON THURSDAY. SCA/SCEC FLAGS WILL BE REQUIRED THROUGH THE END OF THE WEEK. TIDE LEVELS HAVE FALL TO BETWEEN 0.5 AND 0.9 FEET BELOW NORMAL. TIDE LEVELS ARE EXPECTED TO REMAIN NEAR TO SLIGHTLY BELOW NORMAL THROUGH THE WEEKEND. A LOW WATER ADVISORY IS NOT ANTICIPATED. 43 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 47 32 53 34 51 / 10 10 10 10 10 HOUSTON (IAH) 48 33 54 36 54 / 10 10 10 10 10 GALVESTON (GLS) 49 41 54 42 54 / 20 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY. SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH LATE TONIGHT FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. SMALL CRAFT SHOULD EXERCISE CAUTION FROM 3 PM CST THIS AFTERNOON THROUGH LATE TONIGHT FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM... WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...45
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
512 AM CST WED JAN 2 2013 .DISCUSSION... SEE 12Z AVIATION DISCUSSION. && .AVIATION... NAM/GFS FCST SOUNDINGS SHOW MVFR CIGS MIXING OUT BY 15Z WHILE THE RAP KEEPS CIGS IN PLACE THROUGH 18Z. THOUGHT THE RAP MIGHT HAVE A BETTER HANDLE ON THINGS BUT LATEST OBS SHOW MVFR CIGS SCATTERING OUT. FEEL VFR CONDS WILL DEVELOP BY AFTN BUT TIMING STILL A LITTLE IFFY. WINDS WILL BE LIGHTER THAN YESTERDAY ALTHO BRIEFLY HIGHER FOR A FEW HOURS AT KGLS EARLY THIS MORNING. RADAR SHOWS WIDESPREAD LIGHT RAIN BUT OBSERVATION SITES NOT REPORTING RAIN SO IT IS LIKELY VIRGA. WILL NOT BE CARRYING ANY MENTION OF PRECIP IN THIS SET OF TAFS. 43 && .PREV DISCUSSION... /ISSUED 341 AM CST WED JAN 2 2013/ DISCUSSION... BASED ON SFC OBS AND IR SATELLITE IMAGERY IT LOOKS LIKE THERE ARE SEVERAL LAYERS OF CLOUDS WITH LOW MVFR OVC CLOUD DECK BEING THE MOST PROMINENT. AREA RADAR ARE PICKING UP SOME LIGHT RETURNS FROM MID AND HIGH LEVEL CLOUDS BUT NOTHING HITTING THE GROUND GIVEN DRY AIR BELOW 700MB. PRECIP REMAINS CONFINED THE OFFSHORE WATERS OF THE UPPER TX COAST. SFC ANALYSIS HAS WEAK HIGH PRESSURE OVER THE S PLAINS WHICH SHOULD KEEP MODERATE NORTHERLY WINDS IN PLACE TODAY. CLOUD COVER AND WINDS SHOULD HOLD TEMPS IN THE 40S FOR MUCH OF THE DAY WITH MAX TEMPS POSSIBLY REACHING 50 IN A FEW SPOTS. CLOUD COVER WILL BE SLOW TO ERODE GIVEN WESTERLY JET STREAM FLOW. COUPLE OF SHORT WAVE TROUGHS ROTATING THROUGH A MEAN TROUGH OVER THE PLAINS AND C ROCKIES AND THEN A CLOSED LOW OFF THE CALIFORNIA COAST WILL MAINTAIN STRONG WESTERLY FLOW ALOFT THROUGH THE END OF THE WEEK. GIVEN CONTINUED CLOUD COVER AND WEAK NORTHERLY FLOW...WILL KEEP TEMPS A COUPLE OF DEGREES BELOW NORMAL FOR THE REST OF THE WEEK. BY FRIDAY MODELS ARE IN PRETTY GOOD AGREEMENT WITH UPPER LOW OVER S ROCKIES. MODELS THEN BEGIN TO MOVE THIS LOW INTO W TX BY SAT MORNING WITH SOME VORTICITY SHEARING OUT ACROSS THE PLAINS. GFS SEEMS TO BE A BIT FAST WITH STRETCHING OUT THE TROUGH WHILE ECMWF/NAM HAVE A BIT MORE PRONOUNCED TROUGH. MODELS KEEP BULK OF LARGE SCALE ASCENT NORTH OF SE TX BUT STILL ENOUGH FORCING TO TRIGGER SOME RAIN FOR SATURDAY. WILL KEEP 20 POPS IN THE FORECAST FOR RAIN BUT A LOT OF THIS DEPENDS ON HOW STRONG ISENTROPIC LIFT DEVELOPS AND IF ATMOSPHERIC COLUMN MOISTENS ENOUGH. NAM BUFR SOUNDINGS SHOW SOME MOIST PROFILES BY 06-12Z SAT WHICH WOULD SUPPORT RAIN. HIGH PRESSURE BUILDS BACK OVER TX FOR EARLY NEXT WEEK. LOOKS LIKE SOUTHERLY RETURN FLOW DOES NOT SET UP UNTIL TUE/WED NEXT WEEK IN THE FAR EXTENDED FORECAST. UNTIL THEN TEMPS WILL BE VERY CLOSE TO CLIMO NORMS. 39 MARINE... HIGH PRESSURE BUILDING INTO THE SOUTHERN PLAINS WILL MAINTAIN A TIGHT PRESSURE GRADIENT THROUGH THE END OF THE WEEK. A MODERATE NORTH TO NORTHEAST FLOW IS EXPECTED TO PERSIST THROUGH THE END OF THE WEEK. WINDS WILL GENERALLY STAY NEAR OR JUST BELOW SCA CRITERIA THROUGH TONIGHT AND THEN BRIEFLY INCREASE AGAIN ON THURSDAY. SCA/SCEC FLAGS WILL BE REQUIRED THROUGH THE END OF THE WEEK. TIDE LEVELS HAVE FALL TO BETWEEN 0.5 AND 0.9 FEET BELOW NORMAL. TIDE LEVELS ARE EXPECTED TO REMAIN NEAR TO SLIGHTLY BELOW NORMAL THROUGH THE WEEKEND. A LOW WATER ADVISORY IS NOT ANTICIPATED. 43 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 48 32 53 34 51 / 10 10 10 10 10 HOUSTON (IAH) 50 33 54 36 54 / 10 10 10 10 10 GALVESTON (GLS) 51 41 54 42 54 / 20 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY. SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH LATE TONIGHT FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. SMALL CRAFT SHOULD EXERCISE CAUTION FROM 3 PM CST THIS AFTERNOON THROUGH LATE TONIGHT FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM... WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...39 AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
256 PM MST WED JAN 2 2013 .SHORT TERM...WEB CAMS ACROSS MOUNTAINS STILL SHOWING AREAS OF LIGHT SNOW CONFINED MAINLY TO THE CONTINENTAL DIVIDE OF SUMMIT AND GRAND COUNTIES AS WELL AS PORTIONS OF THE GORE RANGE IN WESTERN JACKSON COUNTY. THERE HAS BEEN A GRADUAL DECREASE IN THE LAST FEW HOURS AS DRIER AND SLIGHTLY WARMER AIR SPREADS INTO THE REGION. ACROSS PLAINS....ENOUGH MIXING ALLOWED NORTHWESTERLIES TO MIX TO SURFACE...MAINLY NEAR THE WYOMING BORDER AND FAR EASTERN ZONES. IN ADDITION...SURFACE ANTICYCLONE DEVELOPED NORTH OF DENVER WHICH KEPT WINDS MORE NORTHERLY. LATEST RUC SHOWS ELONGATED UPPER TROUGH CURRENTLY OVER COLORADO MOVING SOUTH DURING THE EVENING WITH FLOW ALOFT BECOMING MORE NORTHERLY. DRIER SUBSIDENT AIR TO CONTINUE TO MOVE ACROSS REGION...SHOULD SEE ANY LINGERING SNOW COME TO AN END WITH CLEARING SKIES. THERE MAY BE A BATCH OF MID LEVEL CLOUD MOVE ACROSS THE EASTERN PLAINS DURING THE EVENING. OTHERWISE...SKIES TO GRADUALLY CLEAR BY MIDNIGHT. AS AIRMASS STABILIZES...SHOULD SEE WINDS DECREASE ACROSS PLAINS BUT REMAIN A BIT GUSTY OVER THE RIDGES. MODELS STILL HINTING A WEAK MOUNTAIN WAVE OVERNIGHT. BUT FLOW ALOFT NOT THAT STRONG AND MORE NORTHERLY. COULD SEE SOME GUSTS APPROACH 50 MPH IN FAVORED AREAS OF GRAND...JACKSON AND PARK COUNTIES AFTER MIDNIGHT. WITH THE CLEARING SKIES AND THE PERSISTANT INVERSIONS ALONG WITH LIGHTER WINDS...SHOULD SEE TEMPS DROP WELL BELOW ZERO IN THE MOUNTAIN VALLEYS AS WELL AS LOW LYING AREAS ACROSS THE PLAINS. DID LOWER MINS NEAR KREMMLING A FEW MORE DEGREES TO ACCOUNT FOR THE CLEARING SKIES. ENOUGH DRAINAGE IN AND NEAR FOOTHILLS TO KEEP TEMPS A BIT WARMER. ON THURSDAY...UPPER TROUGH TO CONTINUE TO MOVE SOUTHEAST AS UPPER RIDGE BUILDS ACROSS COLORADO FROM THE NORTHWEST. THIS WILL RESULT IN A NORTHEAST FLOW ALOFT OVER THE REGION. CROSS SECTIONS INDICATE THE AIRMASS WILL BE FAIRLY DRY WITH MAINLY HIGH LEVEL MOISTURE. TEMPERATURES TO BEGIN TO MODERATE A BIT...THOUGH INVERSIONS WILL LIMIT WARMUP... ESPECIALLY IN LOW LYING AREAS. HIGHS MAY STRUGGLE TO GET ABOVE ZERO NEAR KREMMELING. TEMPERATURES ACROSS THE PLAINS SHOULD BE MAINLY IN THE LOWER 30S...WITH MID TO UPPER 20S NEAR GREELEY. .LONG TERM...THE CURRENT AMPLIFIED RIDGE/TROUGH PATTERN OVER THE EASTERN PACIFIC AND WESTERN UNITED STATES WILL GRADUALLY WEAKEN LATE THURSDAY INTO FRIDAY AS A FAST NORTHEASTWARD MOVING PACIFIC THROUGH OF LOW PRESSURE ENTERS THE PAC NW COAST. THIS WILL WEAKEN THE RIDGE OVER THE ROCKIES AND PROVIDE A FAIRLY DISORGANIZED FLOW PATTERN OVER THE WESTERN HALF OF THE US INCLUDING NE COLO. AS THE WEAKENING RIDGE MOVES EASTWARD AND FLATTENS...THE WARMEST MID LEVEL TEMPS FOLD OVER ONTO THE CENTRAL ROCKIES AND WILL GIVE WAY TO THE START OF WARMER TEMPERATURES EXPECTED IN THE EXTENDED WITH TEMPS REBOUNDING TO NEAR TO ABOVE SEASONAL NORMALS. BY LATE FRIDAY INTO SATURDAY...THE DISORGANIZED FLOW ALOFT OVER THE ROCKIES GIVES WAY TO A VERY WEAK AND DRY UPPER LOW OVER THE OK PANHANDLE. QG VERTICAL VELOCITY FIELDS INDICATE VERY LIGHT LIFT ASSOC WITH THIS OVER NE CO AND WILL KEEP THE PERIOD DRY. THIS UPPER LOW IS EVENTAULLY DRAWN INTO A ALBERTA CLIPPER-TYPE FEATURE DROPPING OUT OF CANADA AND QUICKLY EVACUTES THE REGION TO THE NE US. WILL NEED TO WATCH IN LATER RUNS IF THIS FAST DROPPING CANADIAN TROUGH PUSHES A WEAK BUT DRY COLD FRONT/SURGE INTO EASTERN COLORADO FOR LATE SATURDAY INTO SUNDAY. IF SO...ONLY TEMPS LOOK TO BE COOLED SLIGHTLY FOR SUNDAY. BY SUNDAY...UPPER RIDGE BECOMES FIRMLY REESTABLISHED OVER THE ROCKIES AND CENTRAL US AS THE NEXT UPPER TROUGH APPROACHES THE CALI COAST. TEMP GUIDANCE WOULD SUGGEST TEMPS WARMING TO ABOVE SEASONAL NORMALS...MAINLY FOR THE LOWER ELEVATIONS AND AREAS WITHOUT A SOLID SNOWPACK. STILL EXPECT MTN VALLEYS TO REMAIN COLD DURING THE NIGHT PERIODS. LOOKING TOWARD MONDAY AND INTO THE MIDDLE OF NEXT WEEK...GFS SWINGS ANOTHER FAST MOVING TROUGH OVER THE US/CAN BORDER WHILE A SECOND COLD FRONT LOOKS TO CLIP THE NORTHERN AND EASTERN PORTION OF COLO. AT THIS TIME FRONT LOOKS DRY. BEYOND MONDAY GFS INDICATES VERY BENIGN DRY FLOW OVER THE STATE AS THE TROUGH OFF OF THE CALI COAST DROPS AND WEAKENS INTO THE BAJA REGION. THIS PERIOD ALSO REMAINS DRY WITH NO DISCERNABLE TEMP ADVECTION THROUGHOUT ENTIRE ATMOS. && .AVIATION...ANTICYCLONE NORTH OF THE DENVER AREA HAS KEPT NORTHERLY WINDS AT DEN WITH NORTHEAST WINDS AT BJC AND APA. WINDS HAVE BEEN A BIT GUSTY AT DEN...BUT ARE SHOWING SIGNS OF DECREASING. WINDS TO CONTINUE TO WEAKEN ACROSS THE AREA AIRPORTS AND BECOME MORE SOUTHEAST THROUGH 02Z...THEN SOUTHWEST BY 04Z AS DRAINAGE PATTERN DEVELOPS. VFR TO PREVAIL WITH UNLIMITED CEILINGS. A BATCH OF MID LEVEL CLOUD MAY MOVE ACROSS THE REGION DURING THE EVENING WITH CEILINGS AROUND 10000 FEET FOR A SHORT TIME. ON THURSDAY...SOUTHERLY WINDS TO PREVAIL WITH SPEEDS LESS THAN 10 KTS. WINDS COULD TREND TOWARD THE SOUTHEAST AT DEN AND APA DURING THE AFTERNOON. VFR TO CONTINUE. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....FREDIN AVIATION...D-L
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1022 AM MST WED JAN 2 2013 .UPDATE... ISSUED AT 1020 AM MST WED JAN 2 2013 LOW STRATUS UP TO ABOUT 600MB/-21C CONTINUES TO PRODUCE LIGHT SNOW IN THE AREA EAST OF CRAIG. THE 15Z RAP HOLDS ONTO LIGHT SNOW THERE TO MID AFTERNOON. ELSEWHERE FOG IS SLOSHING AROUND THE UINTAH BASIN WITH PATCHY FOG REPORTED ALONG THE RIVER IN THE GRAND VALLEY. OTHERWISE SUNNY BEAUTIFUL SKIES DOMINATE. STRONG INVERSIONS WILL CONTINUE. THE LOW TEMPERATURE THIS MORNING AT THE GRAND JUNCTION AIRPORT -6F...AT SKYWAY AT 10,600FT ON THE GRAND MESA...-5F. && .SHORT TERM...(TODAY THROUGH THURSDAY) ISSUED AT 311 AM MST WED JAN 2 2013 SNOW BEING REPORTED AT THIS HOUR OVER STEAMBOAT SPRINGS...CRAIG AND MEEKER IN RESPONSE TO SHORT WAVE. SATELLITE IMAGERY CLEARLY SHOWS MID LEVEL CLOUDS MOVING ACROSS THE REGION EXTENDING AS FAR WEST AS THE UTAH BORDER AND NOW REACHING THE SAN JUANS. TEMPS HAVE RESPONDED BY STAYING WARMER THAN SEEN LAST FEW NIGHTS. CURRENT FORECAST STILL CALLS FOR MANY SUB-ZERO LOWS AS CLOUDS DO APPEAR TO BE BREAKING UP SOMEWHAT WHICH SHOULD CAUSE TEMPS TO DROP QUICKLY. IF THIS PROVES TO BE FALSE THOUGH...AN UPDATE WILL BE NEEDED TO BUMP UP LOW TEMPS. MODELS GENERALLY AGREE THAT PRECIP SHOULD END BY 12Z FOR THE AREAS MENTIONED ABOVE BUT NOT SOLD ON IDEA SINCE CROSS SECTIONS SHOW ENOUGH MOISTURE TO KEEP LIGHT SNOW GOING THROUGH AT LEAST EARLY AFTERNOON. FOLLOWED PREVIOUS THINKING AND STARTED LOWERING POPS AFTER NOON WITH HIGHEST ELEVATIONS SEEING CONTINUED LIGHT SNOW SHOWERS AFTER THAT. ACCUMULATIONS WILL BE LIGHT...WHICH LOOKS TO BE PANNING OUT AS SNOTELS ACROSS THE AREA SHOW LITTLE IF ANY ACCUMULATION. BY THIS EVENING...THE UPPER LEVEL TROUGH WILL HAVE SHIFTED SOUTHWARD AS AIRFLOW BECOMES MORE NORTHEAST TO NORTH. THIS FLOW WILL KEEP TEMPERATURES ON THE COLD SIDE AND WITH PLENTY OF CLEAR SKIES EXPECTED...TEMPERATURES WILL BOTTOM OUT YET AGAIN. FOR THURSDAY...A RIDGE OF HIGH PRESSURE WILL BE OVER THE GREAT BASIN WHILE A CLOSED LOW WILL MOVE ACROSS NORTHERN MEXICO BEFORE SHIFTING NORTHEASTWARD INTO NEW MEXICO. AS FAR AS THE RIDGE IS CONCERNED...PIECES OF ENERGY APPROACHING THE PAC NW WILL CAUSE THE RIDGE TO BREAK DOWN. HOWEVER...UTAH AND COLORADO WILL BE BETWEEN THE LOW PRESSURE AND THIS RIDGE SO NO INCLEMENT WEATHER EXPECTED. AS FAR AS OUR WEATHER IS CONCERNED THEN...PLENTY OF SUNSHINE ON TAP WITH INVERSIONS REMAINING IN PLACE KEEPING VALLEY TEMPS WELL BELOW NORMAL. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 311 AM MST WED JAN 2 2013 QUIET WEATHER WILL CONTINUE THROUGH THE REMAINDER OF THE WEEK... THROUGH THE WEEKEND...AND INTO EARLY NEXT WEEK. MODELS HAVE COME INTO MUCH BETTER AGREEMENT THIS MORNING INCREASING CONFIDENCE IN A DRY FORECAST DURING THE MEDIUM RANGE PERIOD. FROM THURSDAY NIGHT INTO FRIDAY...A SHORTWAVE MOVING OVER THE NORTHERN TIER STATES WILL WIPE OUT THE RIDGE WHILE FORCING THE CLOSED LOW CIRCULATION TO THE SOUTH TO EJECT TO THE PANHANDLE REGION OF TEXAS. DRY AIR OVER THE FORECAST AREA BETWEEN THESE SYSTEMS EFFECTIVELY ELIMINATES ANY CHANCE FOR SNOW. THE RIDGE REDEVELOPS THIS WEEKEND AS A DIGGING SYSTEM MOVING OUT OF THE ALASKAN GULF BECOMES ESTABLISHED OFF THE WEST COAST. THE RIDGE AGAIN FLATTENS IN RESPONSE TO A SHORTWAVE MOVING ACROSS THE NORTHERN STATES ON SUNDAY BUT THE AIR MASS WILL REMAIN VERY DRY ACROSS THE WEST. FROM MONDAY INTO TUESDAY A WEAK DEFORMATION REGION FORMS OVER THE AREA AS THE NOW CLOSED LOW CIRCULATION OVER THE EASTERN PACIFIC BEGINS TO MOVE INTO THE DESERT SOUTHWEST. HERE THE MODELS BEGIN TO DIVERGE A BIT AS THE GFS BRINGS THE SYSTEM EASTWARD FASTER THAN THE ECMWF. BY TUESDAY EVENING...THE GFS HAS THE MID LEVEL LOW CENTERED OVER ARIZONA WHILE THE ECMWF HOLD THE LOW OFF THE NORTHERN COAST OF BAJA. REGARDLESS...EVEN THE MORE PROGRESSIVE GFS FAILS TO ADVECT ENOUGH MOISTURE TO GENERATE SHOWERS OVER THE AREA UNTIL LATER IN THE WEEK. TEMPERATURES MODERATE DURING THE EXTENDED PERIOD WITH 7H ISOTHERMS RISING FROM THE -4 TO -8 DEC C RANGE FRIDAY TO 0 TO -2 DEG C BY SUNDAY AND REMAINING STEADY INTO EARLY NEXT WEEK. AS A RESULT... EXPECT MOUNTAIN AREAS TO EXPERIENCE SOME FAIRLY SIGNIFICANT WARMING WHILE INVERTED VALLEYS WILL BE MUCH SLOWER TO WARM. THEREFORE...CONTINUED TO UNDERCUT GUIDANCE FOR MOST LOWER ELEVATION SITES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING) ISSUED AT 1020 AM MST WED JAN 2 2013 AREAS OF IFR FOG EXPECTED TO LIFT FROM KVEL AFT 20Z. ALSO MVFR TO IFR CIGS EAST OF KCAG INCLUDING KHDN AND KSBS EXPECTED TO BECOME AFT 21Z. OTHERWISE VFR CONDITIONS DOMINATE. BASIN FOG RETURNS AFT 06Z TONIGHT MAINLY AFFECTING KVEL. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...JOE SHORT TERM...TGR LONG TERM...NL AVIATION...TGR
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1019 AM MST WED JAN 2 2013 .AVIATION... KCOS AND KPUB...VFR CONDITIONS THROUGH THE NEXT 24 HOURS WITH LIGHT DIURNALLY DRIVEN WINDS. KALS...CIGS AND VIS HAVE IMPROVED AS FOG HAS DISSIPATED. EXPECT VFR CONDITIONS BEYOND 19Z FOR THE REMAINDER OF THE AFTERNOON AND EARLY EVENING. EXPECT FOG TO REDEVELOP AROUND 04Z TONIGHT AND PERSIST INTO THURSDAY MORNING WITH IFR TO LIFR CONDITIONS. MOZLEY && .PREV DISCUSSION... /ISSUED 404 AM MST WED JAN 2 2013/ SHORT TERM... (TODAY AND TONIGHT) CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS IS INDICATING MODERATE TO STRONG NORTHERLY FLOW ALOFT ACROSS THE REGION AS A BROAD UPPER TROUGH PERSISTS ACROSS THE UPPER MIDWEST THROUGH THE HIGH PLAINS AND A HIGH AMPLITUDE RIDGE IS IN PLACE ACROSS THE WEST COAST AT THIS TIME. WATER VAPOR IMAGERY IS ALSO INDICATING AN EMBEDDED SHORT WAVE TRANSLATING ACROSS THE NORTHERN ROCKIES WITH MORE ENERGY DIVING DOWN THE BACK SIDE OF THE UPPER RIDGE ACROSS WESTERN CANADA AT THIS TIME. REGIONAL SATELLITE AND RADAR DATA INDICATING SOME MID LEVEL MOISTURE SPREADING SOUTHEAST ACROSS NORTHERN COLORADO ALONG WITH A FEW ECHOES MOVING ACROSS NORTHEASTERN COLORADO AND NORTHWESTERN KANSAS AT THIS TIME. SATELLITE DATA ALSO INDICATING COLD TEMPERATURES ACROSS THE HIGH MT VALLEYS ALONG WITH PATCHY FREEZING FOG. TODAY...EMBEDDED NORTHERN ROCKIES SHORTWAVE CONTINUES TO TRANSLATE INTO THE NORTHERN HIGH PLAINS WHICH SENDS A WEAK BACKDOOR COLD FRONT ACROSS EASTERN COLORADO THIS MORNING AS SFC HIGH PRESSURE BUILDS ACROSS THE HIGH PLAINS. GENERALLY WEAK NORTHERLY WINDS ACROSS THE PLAINS THIS MORNING TO BECOME LIGHT UPSLOPE THROUGH THE AFTERNOON AND WITH A COLD AIRMASS IN PLACE...SHOULD SEE HIGHS AROUND YESTERDAYS READINGS. MODELS IN GENERAL AGREEMENT WITH KEEPING PRECIPITATION MAINLY ACROSS NORTHERN AND NORTHEASTERN COLORADO THIS MORNING...THOUGH HAVE KEPT SLIGHT POPS ACROSS THE EASTERN SAWATCH RANGE NORTH OF COTTONWOOD PASS. THE HI RES RAP MODEL HAS BEEN PRINTING OUT SOME LIGHT QPF ACROSS PIKES PEAK AND THE SANGRE DE CRISTO MTS THIS AFTERNOON WHICH SEEMS POSSIBLE WITH DEVELOPING LOW LEVEL UPSLOPE FLOW AND CONTINUED COLD AIR ALOFT. AT ANY RATE...HAVE KEPT A DRY FORECAST INTACT FOR THIS AFTERNOON THOUGH LATER SHIFTS WILL NEED TO CONTINUE TO MONITOR FOR A FEW POSSIBLE SHOWERS. TONIGHT...MODERATE NORTHERLY FLOW ALOFT CONTINUES AS NEXT EMBEDDED WAVE DIGS ACROSS THE NORTHERN ROCKIES. MODELS CONTINUE TO KEEP THE AREA DRY...THOUGH DO INDICATE SOME MID LEVEL MOISTURE SPREADING ACROSS THE EASTERN PLAINS THROUGH THE EARLY MORNING HOURS. AGAIN WITH THE COLD AIRMASS IN PLACE AND MOSTLY CLEAR SKIES THROUGH THE EVENING HOURS...SHOULD SEE TEMPERATURES TANK AFTER SUNSET WITH SOME POSSIBLE WARMING ACROSS THE EASTERN PLAINS INTO THE EARLY MORNING. WITH THAT SAID...HAVE GONE AT OR BELOW THE COLDER SIDE OF GUIDANCE ESPECIALLY ACROSS THE MTS AND HIGH MT VALLEYS. -MW LONG TERM... (THURSDAY THROUGH TUESDAY) LATEST MODEL RUNS SHOW TROF AXIS LINGERING JUST TO OUR SOUTH THURSDAY AS RIDGE AXIS NOSES INTO WY BY FRIDAY. MOISTURE AND PRECIPITATION REMAIN WELL TO OUR SOUTH DURING THIS PERIOD WITH TEMPERATURES WARMING THROUGH FRIDAY. SNOW COVERED AREAS WILL REMAIN COOLER THAN THOSE LOCATIONS WITHOUT SNOW COVER. NEXT SHORTWAVE MOVES OVER THE TOP OF THE RIDGE AND SOUTH THROUGH THE HIGH PLAINS LATE FRIDAY NIGHT AND SATURDAY. AT THE SURFACE...A COLD FRONT MOVES SOUTH THROUGH THE PLAINS SATURDAY...BUT LIMITED MOISTURE KEEPS THE FORECAST DRY. TEMPERATURES WILL BE A BIT COOLER EAST OF THE MOUNTAINS SATURDAY. UPPER RIDGE AXIS RETURNS FOR SUNDAY AND MONDAY WITH TEMPERATURES WARMING ONCE AGAIN FOR MOST LOCATIONS. SNOW COVER WILL CONTINUE TO BE A FACTOR IN DAILY HIGH AND LOW TEMPERATURES. STRONG INVERSIONS WILL STILL DEVELOP IN THE SAN LUIS VALLEY...KEEPING HIGHS IN THE TEENS TO LOWER 20S AND LOWS IN THE TEENS AND 20S BELOW ZERO. WHILE THE GFS HAS BEEN CONSISTENT THE PAST FEW RUNS SHOWING A CLOSED LOW OFF THE SOUTHERN CALIFORNIA COAST BY EARLY NEXT WEEK ..ECMWF NOW ALSO DEPICTING THIS SOLUTION. STILL SOME DIFFERENCES IN TIMING AND TRACK OF THIS SYSTEM WITH THE GFS WEAKER AND MORE PROGRESSIVE WEDNESDAY INTO THURSDAY. THE TRACK SHOWS SOME POTENTIAL FOR SNOW IN FAR SOUTHERN COLORADO NEXT WEDNESDAY...BUT LATER SHIFTS WILL HAVE TO MONITOR MODELS TO FINE TUNE THE FORECAST IN THE COMING DAYS. 40 AVIATION... VFR CONDITIONS EXPECTED FOR THE NEXT 24 HOURS AT KCOS AND KPUB WITH POSSIBLE MID LEVEL CIGS THIS AFTERNOON WITH DEVELOPING UPSLOPE LOW LEVEL FLOW. OCCASIONAL IFR AND LIFR CONDITIONS IN PATCHY FZFG TO PERSIST AT KALS THROUGH 16Z WITH VFR CONDITIONS AND COLD TEMPERATURES EXPECTED THERE AFTER. MODELS INDICATING SIMILAR CONDITIONS POSSIBLE AGAIN THIS LATER EVENING...BUT NOT ENOUGH CONFIDENCE TO INCLUDE IN TAF AT THIS TIME. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 88/50
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
939 AM MST WED JAN 2 2013 .UPDATE... && .SHORT TERM...LIGHT SNOW STILL PERSISTING ACROSS WASHINGTON AND NORTHERN LINCOLN COUNTIES...SLOWLY TREKING SOUTH-SOUTHEAST. SOME ECHOES UPSTREAM OVER WYOMING AND NEBRASKA. AREAS OF LIGHT SNOW ALSO OCCURING ACROSS MOUNTAINS...MAINLY ALONG THE CONTINENTAL DIVIDE...AS SHOWN BY WEB CAMS. PRECIP BEING GENERATED BY WEAK MID LEVEL QG ASCENT ASSOCIATED WITH UPPER TROUGH CURRENTLY MOVING ACROSS THE REGION. MODELS CONTINUE TO SHOW AIRMASS DRYING OUT THIS AFTERNOON AS TROUGH MOVES AWAY FROM REGION AND SUBSIDENCE SPREADS ACROSS THE AREA. AIRMASS TO REMAIN SLIGHTLY UNSTABLE THROUGH THE AFTERNOON...SO THERE MAY STILL BE SOME LINGERING FLURRIES OVER THE REGION DURING THE AFTERNOON. OVERALL CURRENT FORECASTS LOOK REASONABLE...BUT DID KEEP A MENTION OF LIGHT SNOW ACROSS THE FAR PLAINS THROUGH THE MORNING. WILL CONTINUE THE TREND OF DECREASING CLOUDS. WILL LEAVE THE TEMPS AS IS FOR NOW...BUT MAY NEED TO MAKE ADJUSTMENTS TO THE MIN TEMPS IF SKIES CLEAR SOONER THAN ANTICIPITATED. .AVIATION...WINDS MAINTAINING A SOUTHWEST DIRECTION AT AREA AIRPORTS. LATEST RAP AND HRRR SUGGESTING THE DEVELOPMENT OF AN ANTICYCLONE NORTH OF THE AREA WHICH WOULD SHIFT THE WINDS TO A NORTHEAST DIRECTION DURING THE AFTERNOON. STILL SOME QUESTION WHETHER WINDS WILL INITIALLY GO CLOCKWISE OR COUNTERCLOCKWISE. FOR NOW WILL CONTINUE THE TREND OF THE CURRENT TAFS...WITH PERHAPS A VARIABLE DIRECTION FOR AN HOUR OR SO BEFORE GOING NORTHEAST. SPEEDS TO REMAIN BELOW 12 KTS. SLIGHT CHANCE OF CEILINGS AROUND 6000 FEET AGL FOR SHORT PERIODS DURING THE AFTERNOON. CONFIDENCE TOO LOW TO INCLUDE IN THE TAF FOR NOW. && .PREV DISCUSSION... /ISSUED 420 AM MST WED JAN 2 2013/ SHORT TERM...UPPER TROUGH WILL DROP ACROSS COLORADO TODAY AND TONIGHT WITH FLOW ALOFT BECOMING NNE. DETAILS STILL MESSY...THERE IS A WEAK TROUGH PASSING OUR AREA NOW WITH FAIRLY WIDESPREAD FLURRIES ON THE PLAINS. THE MAIN TROUGH AXIS WITH THE COLDEST AIR ALOFT APPEARS TO BE SCHEDULED FOR LATE AFTERNOON OR EARLY EVENING...BUT THERE IS STILL SOME CLOUD COVER FOR A WAYS BEHIND THAT AS THE WEAK INSTABILITY WILL GIVE WAY TO A LITTLE LIFT FROM WARM ADVECTION...THEN SUBSIDENCE AND CLEARING COMING IN FROM THE NORTH BY THURSDAY MORNING. CLOUD COVER AGAIN WILL BE DIFFICULT...THERE IS LOTS OF CONVECTION UPSTREAM THOUGH IT IS WEAK AND HIGH BASED AND HAS PLENTY OF HOLES IN IT AS WELL. THERE DOES APPEAR TO BE STEADY DRYING...AND I WILL STICK WITH THE IDEA THAT THIS WILL WIN OVER EVERYTHING ELSE WITH A GENERAL SLOW DECREASE IN CLOUD COVER THROUGH THE DAY. STILL COULD BE A FEW FLAKES HERE AND THERE...BUT AFTER THE NEXT COUPLE HOURS NOT WORTH MENTIONING EXCEPT IN THE MOUNTAINS...AND EVEN THERE IT LOOKS LIKE DRYING FROM THE WEST SHOULD SHUT THINGS DOWN THIS MORNING. MAIN CHANGES WERE TO ACCOUNT FOR CURRENT CONDITIONS...WARMER AND MOISTER ON THE NORTHEAST PLAINS...ALMOST A BACKDOOR WARM FRONT IF THERE IS SUCH A THING. DENVER AREA WINDS LOOK TRICKY BUT MODEL GUIDANCE SHOWS THE ANTICYCLONE PERSISTING WITH SOUTHERLY WINDS OVER DENVER THROUGH THE DAY...SO WE WILL STICK WITH THAT IDEA AS WELL. PROBABLY ENOUGH OF A WESTERLY COMPONENT STILL TO FORCE THE TURNING...AND STILL A LITTLE LOW LEVEL STABILITY TO PREVENT MIXING OVER DENVER AND MAINTAIN THE CIRCULATION. TWEAKED LOW TEMPERATURES TONIGHT TOWARD THE LATEST GUIDANCE WHICH IS COLDER IN THE COLDEST SPOTS. WHILE THERE WILL BE SOME CLOUDS BEHIND THE TROUGH AXIS FOR A WHILE...EXPECT CLEARING IN THE NORTH AND WEST PARTS OF OUR AREA BY MORNING...AND PROBABLY SOON ENOUGH TO ALLOW FOR TEMPERATURES TO DROP. SOME CONCERN ABOUT EARLIER CLEARING THAT WOULD LET IT GET COLDER...NAM MOS HAS -28 AT KREMMLING AND -13 AT GREELEY WHICH MAY NOT BE COLD ENOUGH IF IT DOES CLEAR EARLY IN THE NIGHT. SHOULD BE SOME DRAINAGE WIND IN USUAL SPOTS TO KEEP THE FOOTHILLS AND DENVER WARMER...THOSE AREAS COULD EVEN BE WARMING OVERNIGHT AGAIN. FINALLY...HINTS OF A NELY MOUNTAIN WAVE SETUP LATE TONIGHT AS THE WARM ADVECTION SETS IN. FLOW NOT THAT STRONG AND MORE NLY THAN NE...SO WOULD MAINLY AFFECT THE FAIRPLAY AREA AND MAYBE SOME SPARSELY POPULATED SPOTS IN GRAND AND JACKSON COUNTIES...DO NOT THINK THERE IS MUCH HIGH WIND THREAT BUT COULD BE POCKETS OF 50 MPH GUSTS WHERE THE TERRAIN IS SHAPED RIGHT. LONG TERM...AN UPPER LEVEL RIDGE WILL BUILD INTO COLORADO FROM THE NORTH AND WEST ON THURSDAY WITH A DRY NORTHEASTERLY FLOW ALOFT OVER THE CWFA. THE FLOW ALOFT WILL REMAIN DRY ON FRIDAY WITH A WEAK UPPER TROUGH PASSING TO THE SOUTH AND EAST. TEMPERATURES WILL MODIFY TO NEAR SEASONAL NORMALS BY THAT TIME. THE FLOW ALOFT WILL INCREASE AND BECOME NORTHWESTERLY FRIDAY NIGHT INTO SATURDAY AS A WEAK UPPER LEVEL DISTURBANCES PASSES FROM THE NRN GREAT PLAINS AND INTO THE MIDWEST. ONLY EFFECT FM THIS WILL BE A SLIGHT DECREASE IN AFTN TEMPERATURES ON SATURDAY FOR THE NORTHEAST PLAINS. OTHERWISE UPPER LEVEL RIDGING OVER THE WESTERN U.S WILL KEEP THE AMS OVER COLORADO DRY AND STABLE. THE DRY PATTERN WILL CONTINUE INTO EARLY NEXT WEEK. THE RIDGE WILL FLATTEN SOMEWHAT WITH THE STORM TO THE NORTH OF COLORADO. AN EMBEDDED DISTURBANCE IS POSSIBLE BUT OVERALL THE PATTERN STILL LOOKS QUITE BENIGN SO WILL KEEP IT DRY. AVIATION...VFR CONDITIONS WITH LIGHT WINDS TODAY. CEILINGS WILL GENERALLY BE ABOVE 6000 FT AGL THOUGH THERE IS A CHANCE OF SLIGHTLY LOWER CEILINGS FOR SHORT PERIODS. SOUTH WINDS WILL PREVAIL THOUGH THERE IS SOME UNCERTAINTY ABOUT THE DIRECTION THIS AFTERNOON...SPEEDS UNDER 12 KNOTS. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....COOPER AVIATION...D-L
AREA FORECAST DISCUSSION
NWS PUEBLO CO
404 AM MST WED JAN 2 2013 .SHORT TERM... (TODAY AND TONIGHT) CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS IS INDICATING MODERATE TO STRONG NORTHERLY FLOW ALOFT ACROSS THE REGION AS A BROAD UPPER TROUGH PERSISTS ACROSS THE UPPER MIDWEST THROUGH THE HIGH PLAINS AND A HIGH AMPLITUDE RIDGE IS IN PLACE ACROSS THE WEST COAST AT THIS TIME. WATER VAPOR IMAGERY IS ALSO INDICATING AN EMBEDDED SHORT WAVE TRANSLATING ACROSS THE NORTHERN ROCKIES WITH MORE ENERGY DIVING DOWN THE BACK SIDE OF THE UPPER RIDGE ACROSS WESTERN CANADA AT THIS TIME. REGIONAL SATELLITE AND RADAR DATA INDICATING SOME MID LEVEL MOISTURE SPREADING SOUTHEAST ACROSS NORTHERN COLORADO ALONG WITH A FEW ECHOES MOVING ACROSS NORTHEASTERN COLORADO AND NORTHWESTERN KANSAS AT THIS TIME. SATELLITE DATA ALSO INDICATING COLD TEMPERATURES ACROSS THE HIGH MT VALLEYS ALONG WITH PATCHY FREEZING FOG. TODAY...EMBEDDED NORTHERN ROCKIES SHORTWAVE CONTINUES TO TRANSLATE INTO THE NORTHERN HIGH PLAINS WHICH SENDS A WEAK BACKDOOR COLD FRONT ACROSS EASTERN COLORADO THIS MORNING AS SFC HIGH PRESSURE BUILDS ACROSS THE HIGH PLAINS. GENERALLY WEAK NORTHERLY WINDS ACROSS THE PLAINS THIS MORNING TO BECOME LIGHT UPSLOPE THROUGH THE AFTERNOON AND WITH A COLD AIRMASS IN PLACE...SHOULD SEE HIGHS AROUND YESTERDAYS READINGS. MODELS IN GENERAL AGREEMENT WITH KEEPING PRECIPITATION MAINLY ACROSS NORTHERN AND NORTHEASTERN COLORADO THIS MORNING...THOUGH HAVE KEPT SLIGHT POPS ACROSS THE EASTERN SAWATCH RANGE NORTH OF COTTONWOOD PASS. THE HI RES RAP MODEL HAS BEEN PRINTING OUT SOME LIGHT QPF ACROSS PIKES PEAK AND THE SANGRE DE CRISTO MTS THIS AFTERNOON WHICH SEEMS POSSIBLE WITH DEVELOPING LOW LEVEL UPSLOPE FLOW AND CONTINUED COLD AIR ALOFT. AT ANY RATE...HAVE KEPT A DRY FORECAST INTACT FOR THIS AFTERNOON THOUGH LATER SHIFTS WILL NEED TO CONTINUE TO MONITOR FOR A FEW POSSIBLE SHOWERS. TONIGHT...MODERATE NORTHERLY FLOW ALOFT CONTINUES AS NEXT EMBEDDED WAVE DIGS ACROSS THE NORTHERN ROCKIES. MODELS CONTINUE TO KEEP THE AREA DRY...THOUGH DO INDICATE SOME MID LEVEL MOISTURE SPREADING ACROSS THE EASTERN PLAINS THROUGH THE EARLY MORNING HOURS. AGAIN WITH THE COLD AIRMASS IN PLACE AND MOSTLY CLEAR SKIES THROUGH THE EVENING HOURS...SHOULD SEE TEMPERATURES TANK AFTER SUNSET WITH SOME POSSIBLE WARMING ACROSS THE EASTERN PLAINS INTO THE EARLY MORNING. WITH THAT SAID...HAVE GONE AT OR BELOW THE COLDER SIDE OF GUIDANCE ESPECIALLY ACROSS THE MTS AND HIGH MT VALLEYS. -MW .LONG TERM... (THURSDAY THROUGH TUESDAY) LATEST MODEL RUNS SHOW TROF AXIS LINGERING JUST TO OUR SOUTH THURSDAY AS RIDGE AXIS NOSES INTO WY BY FRIDAY. MOISTURE AND PRECIPITATION REMAIN WELL TO OUR SOUTH DURING THIS PERIOD WITH TEMPERATURES WARMING THROUGH FRIDAY. SNOW COVERED AREAS WILL REMAIN COOLER THAN THOSE LOCATIONS WITHOUT SNOW COVER. NEXT SHORTWAVE MOVES OVER THE TOP OF THE RIDGE AND SOUTH THROUGH THE HIGH PLAINS LATE FRIDAY NIGHT AND SATURDAY. AT THE SURFACE...A COLD FRONT MOVES SOUTH THROUGH THE PLAINS SATURDAY...BUT LIMITED MOISTURE KEEPS THE FORECAST DRY. TEMPERATURES WILL BE A BIT COOLER EAST OF THE MOUNTAINS SATURDAY. UPPER RIDGE AXIS RETURNS FOR SUNDAY AND MONDAY WITH TEMPERATURES WARMING ONCE AGAIN FOR MOST LOCATIONS. SNOW COVER WILL CONTINUE TO BE A FACTOR IN DAILY HIGH AND LOW TEMPERATURES. STRONG INVERSIONS WILL STILL DEVELOP IN THE SAN LUIS VALLEY...KEEPING HIGHS IN THE TEENS TO LOWER 20S AND LOWS IN THE TEENS AND 20S BELOW ZERO. WHILE THE GFS HAS BEEN CONSISTENT THE PAST FEW RUNS SHOWING A CLOSED LOW OFF THE SOUTHERN CALIFORNIA COAST BY EARLY NEXT WEEK ...ECMWF NOW ALSO DEPICTING THIS SOLUTION. STILL SOME DIFFERENCES IN TIMING AND TRACK OF THIS SYSTEM WITH THE GFS WEAKER AND MORE PROGRESSIVE WEDNESDAY INTO THURSDAY. THE TRACK SHOWS SOME POTENTIAL FOR SNOW IN FAR SOUTHERN COLORADO NEXT WEDNESDAY...BUT LATER SHIFTS WILL HAVE TO MONITOR MODELS TO FINE TUNE THE FORECAST IN THE COMING DAYS. STARK && .AVIATION... VFR CONDITIONS EXPECTED FOR THE NEXT 24 HOURS AT KCOS AND KPUB WITH POSSIBLE MID LEVEL CIGS THIS AFTERNOON WITH DEVELOPING UPSLOPE LOW LEVEL FLOW. OCCASIONAL IFR AND LIFR CONDITIONS IN PATCHY FZFG TO PERSIST AT KALS THROUGH 16Z WITH VFR CONDITIONS AND COLD TEMPERATURES EXPECTED THERE AFTER. MODELS INDICATING SIMILAR CONDITIONS POSSIBLE AGAIN THIS LATER EVENING...BUT NOT ENOUGH CONFIDENCE TO INCLUDE IN TAF AT THIS TIME. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/40
AREA FORECAST DISCUSSION
NWS GAYLORD MI
103 PM EST WED JAN 2 2013 .SYNOPSIS... ISSUED AT 449 AM EST WED JAN 2 2013 OCCASIONAL LAKE EFFECT SNOW SHOWERS WILL CONTINUE FOR MOST OF THIS WEEK...WITH A MORE ROBUST PERIOD OF LAKE ENHANCED SNOW THURSDAY...AS THE NEXT CLIPPER SYSTEM MOVES THROUGH THE AREA. WARMER AND DRIER AIR THEN BEGIN TO MOVE INTO THE REGION FRIDAY AND OVER THE WEEKEND FOR SIGNIFICANTLY LOWER SNOW CHANCES. && .UPDATE... ISSUED AT 1256 PM EST WED JAN 2 2013 LES LIGHT SNOW AND FLURRIES CONTINUES ACROSS THE REGION. ADDED A LITTLE TO ACCUMULATIONS NEAR THE TIP OF THE MIT WHERE VSBYS HAVE BEEN DOWN TO 1 1/2 AT TIMES...BUT STILL ONLY HAVE 1 TO 2 INCHES TOTAL DAYTIME ACCUMULATIONS. OTHERWISE...JUST SOME MINOR TWEAKS FOR TIMING/COVERAGE. UPDATE ISSUED AT 1008 AM EST WED JAN 2 2013 NO BIG CHANGES TO THE FORECAST. EXTENDED LAKE EFFECT FLURRIES INTO EARLY AFTERNOON ACROSS EASTERN COUNTIES AS THE FLOW REMAINS WESTERLY (BEFORE BACKING INTO THE SOUTHWEST LATER ON). OTHERWISE...LOWERED MAXES BY A DEGREE OR TWO MOST SPOTS (EXCEPT FOR NEAR THE LAKE MICHIGAN SHORELINE WHERE HAD TO ADD A DEGREE OR SO). UPDATE ISSUED AT 638 AM EST WED JAN 2 2013 FORECAST GOING ALONG TO PLAN THIS MORNING WITH FLURRIES IN THE WESTERLY FLOW REGIMES...EXPANDED FROM INVADING WIDESPREAD LOW LEVEL STRATUS. THIS STRATUS HAS COVERED ALMOST EVERYONE (ALPENA WITHIN THE NEXT HOUR OR SO). THERE IS A LOSS OF CONFIDENCE IN THE DEVELOPMENT OF A PRETTY GOOD BAND OF SNOW OUT OVER LAKE HURON. THE DRAINAGE FLOW INTO THIS AREA...IS LAGGING BY A FEW HOURS. SO REMOVED THE HIGH CHANCES FOR SNOW...AND CERTAINLY FOR THE NE LOWER COAST. WILL HOLD ON TO SOME HOPE BY EARLY AFTERNOON...BUT NOT SO SURE ABOUT THAT EITHER. ALL OF NRN LOWER SHOULD MAINLY SEE FLURRIES...UNTIL LATER THIS AFTERNOON...WHEN INCREASING MOISTURE AND A SW FLOW MAY BRING A FEW TENTHS TO THE NW LOWER COAST. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 449 AM EST WED JAN 2 2013 WEAK HIGH PRESSURE WAS SETTLED IN OVER THE REGION...WITH MUCH COLDER AIR ACROSS ONTARIO DRAINING IN ACROSS EASTERN LAKE SUPERIOR...ENHANCING A LOW LEVEL COLD FRONT/CONVERGENCE. THIS CONVERGENCE AND AIR FLOW OVER LAKE SUPERIOR PRODUCED QUITE THE MODERATE/INTENSE SNOW BAND THAT FILTERED IN MAINLY JUST THE PARADISE AREA A FEW HOURS BACK. THIS BAND OF SNOW HAS WEAKENED OVER EASTERN UPPER DUE TO LOSS OF A DECENT FETCH. THE REST OF NRN MICHIGAN WAS SEEING A RAPIDLY APPROACHING STRATUS LAYER FROM LAKE MICHIGAN AND WISCONSIN...WITH A CONTINUED EXPECTATION TO SWEEP OVER ALL OF THE REGION. CLEAR SKIES IN SPOTS ACROSS FAR NRN LOWER AND NE LOWER WILL BECOME CLOUDY AGAIN. FLURRIES WERE STILL FAIRLY PREVALENT OUTSIDE OF THE CLEAR REGIONS...AND THE UPSTREAM CLOUDS ALSO CONTAIN FLURRIES. RADAR SHOWING THIS IS THE CASE...WITH NEW ECHOES POPPING UP OVER LAKE MICHIGAN. TEMPERATURES WERE IN THE TEENS AND LOWER 20S. NEXT ALBERTA CLIPPER WAS MOVING INTO FAR NRN MN WITH TROUGHING EXTENDING EASTWARD AND CONNECTING WITH THE ENHANCED TROUGHING FROM THE COLD AIR DRAINAGE/COLD FRONT. THE SYSTEM COLD FRONT WAS DRAPED THROUGH EASTERN ND/SD AND DOWN INTO NEBRASKA. DEEPER MOISTURE WAS SEEN VIA SATELLITE ALONG AND BEHIND THE COLD FRONT...AS WELL AROUND THE NRN PERIPHERY OF THE LOW PRESSURE. TODAY AND TONIGHT...WILL BE RAMPING FOR THE ARRIVAL OF THE CLIPPER LATE TONIGHT AND INTO THURSDAY. THE STRATUS FROM WISCONSIN WAS ERODING FROM THE SW...WITHIN WEAK WARM AIR ADVECTION INTO THE CLOUD LAYER. NOT WORRIED TOO MUCH ABOUT THIS WARM ADVECTION ERODING THE STRATUS FOR US...SINCE LOW LEVEL TEMPS OF -8C TO -10C HOLD THROUGHOUT THE DAY...SUFFICIENT COLD ENOUGH TO KEEP NOT ONLY CLOUDS IN PLACE...BUT TO ALSO ALLOW FOR THE CONTINUED GENERATION OF LAKE EFFECT FLURRIES. THESE FLURRIES WILL BE WITHIN WEST FLOW REGIMES THIS MORNING...THEN SW FLOW REGIMES AS WINDS BACK AHEAD OF THE APPROACHING LOW PRESSURE. ONE FLY IN THE OINTMENT THAT COULD HAVE SOME SIGNIFICANT RAMIFICATIONS IN THE SNOWFALL/AMOUNTS IS FOR THE DRAINAGE FLOW FROM ONTARIO...EXPECTED TO ENHANCE CONVERGENCE OVER LAKE HURON...WHICH COULD NEAR THE NE LOWER SHORELINE. HI RES MODELS/LATEST RUC ARE STEADFAST ON THIS IDEA BY DAYBREAK...WITH THE DEVELOPMENT OF ANOTHER MODERATE/INTENSE LAKE SNOW BAND. CONFIDENCE IN THIS ISN`T THE GREATEST...DUE IN PART TO THE DRAINAGE LAGGING THE HI RES TIMING (NOT EVEN INTO THE SAULT RIGHT NOW)...AND THAT MIXING INTO THE MORNING MIGHT KEEP THE CONVERGENCE WELL OUT INTO NRN LAKE HURON...NOT THREATENING OUR COASTAL AREAS. THIS IS SOMETHING TO KEEP A CLOSE EYE ON...AS THE ARRIVAL OF THE CONVERGENCE INTO FAR NRN LOWER AND EASTERN UPPER...WOULD ENHANCE CONVERGENCE AND RESULT IN STRONGER THAN EXPECTED SNOWS. AGAIN...NOT ENTIRELY SOLD ON THIS. DID INCREASE CHANCES FOR SEEING BONA FIDE SNOWS AND SMALL ACCUMULATIONS...BUT FEELING IS FOR ANY ACCUMS TO REMAIN UNDER AN INCH. WE WILL HAVE TO WAIT FOR INCREASED SW WINDS AND DEEPER MOISTURE AHEAD OF THE CLIPPER`S COLD FRONT. THIS HAPPENS THROUGH THE NIGHT...BUT MAINLY AFTER MIDNIGHT. INCREASED MOISTURE FLUX OFF THE LAKES WILL HELP...BUT INVERSION HEIGHTS RISING TO MAYBE 4500-5000FEET WITH DELTA T`S UNDER 15C...AND NO GOOD SUPPORT ALOFT WILL MORE LIKELY RESULT IN ACCUMULATIONS IN THE 1-2 INCH RANGE WITH A SLIVER OF AN AREA ACROSS CENTRAL CHIP/MACK COUNTIES...AND EMMET COUNTY SEEING UP TO 3 INCHES. IF THERE IS A LAKE HURON BAND OF SNOW THAT DEVELOP THIS MORNING...THE SW FLOW WILL GRADUALLY PUSH THIS SNOW IN ACROSS DRUMMOND ISLAND BEFORE DEPARTING EAST OF THERE. VERY DIFFICULT MESOSCALE FORECAST IN THE SHORT TERM. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 449 AM EST WED JAN 2 2013 ENERGETIC SPLIT FLOW PATTERN SET TO CONTINUE...WITH ONE LAST NORTHERN STREAM ORIGINATED SHORTWAVE SET TO VISIT OUR AREA LATER TONIGHT INTO THURSDAY. AFTERWARD...NORTHERN STREAM PROGGED TO RETREAT NORTH...BOTTLING UP THE ARCTIC COLD WELL TO OUR NORTH FOR THE FORESEEABLE FUTURE...PART OF A BURGEONING POSITIVE AO SIGNATURE AND EAST DISPLACED NORTH ATLANTIC BLOCKING. NOT TO SAY THE PATTERN DOESN`T HOLD AT LEAST SOME SNOW POTENTIAL FOR THE SNOW ENTHUSIASTS AMONGST US...WITH THURSDAY`S LEAD CHARGING SYSTEM HAVING THE LOOKS OF A RATHER SNEAKY LAKE ENHANCED SNOW EVENT FOR THE TRADITIONAL SNOWBELTS. TAKING A LOOK EVEN FURTHER OUT...MAY SEE THE BEGINNINGS OF THE INFAMOUS "JANUARY THAW" HEADING INTO NEXT WORK WEEK...WITH WELL AGREED UPON PROGS SUGGESTING A FURTHER RELAXATION OF THE NORTHERN STREAM AND A FLOODING OF MODIFIED PACIFIC AIR ACROSS THE CONUS. LARGE SCALE INDICES WOULD TEND TO AGREE...ALTHOUGH WITH DOMINATE POLAR VORTEX ON THIS SIDE OF THE GLOBE...HAVE SOME SUSPICION NORTHERN STREAM WILL NOT YIELD AS AGGRESSIVELY AS SOME PROGS WOULD SUGGEST. GETTING A TOUCH AHEAD OF MYSELF...AND STILL HAVE AMPLE CONCERNS IN THE SHORT TERM PORTION OF THE LONG TERM TO DEAL WITH...MOST NOTABLY THURSDAY`S SNOW POTENTIAL. DEFINITELY AN INTRIGUING SYSTEM FOR THURSDAY AS FAST MOVING AREA OF LOW PRESSURE SLICES ACROSS LAKE SUPERIOR EARLY...DRAGGING AN EQUALLY FAST MOVING COLD FRONT THROUGH NORTHERN MICHIGAN DURING THE MORNING. WHILE CORE OF BETTER MID LEVEL DYNAMICS LOOK TO PASS BY JUST TO OUR NORTH..STILL DECENT SLUG OF UPWARD QG SUPPORT ALONG SHARP SHORTWAVE TROUGH AXIS PASSING OVERHEAD. DEEP LAYER MOISTURE NOTHING TO WRITE HOME ABOUT...WITH PWAT VALUES STRUGGLING TO EXCEED A QUARTER OF AN INCH. STILL...WOULD EXPECT AT LEAST SOME SYNOPTIC DRIVEN SNOWS TO ACCOMPANY SHORTWAVE PASSAGE DURING THE MORNING. WILD CARD REMAINS LAKE ENHANCEMENT POTENTIAL...BOTH ALONG AND PROCEEDING COLD FRONTAL PASSAGE. PREFRONTAL AIRMASS MORE THAN COLD ENOUGH TO SUPPORT LAKE ENHANCED SNOWS...PARTICULARLY AS CONVERGENCE IS MAXIMIZED ALONG FRONTAL SLOPE. TEMPERATURES COOL FURTHER IMMEDIATELY BEHIND THE FRONT...WITH H85 READINGS APPROACHING THE NEGATIVE MIDDLE TEENS BY AFTERNOON. MOISTURE REMAINS ABUNDANT UNTIL MID LEVEL TROUGH PASSAGE DURING THE AFTERNOON...SUGGESTING AT LEAST A SEVERAL HOUR WINDOW OF GOOD LAKE ENHANCED SNOWS IN FAVORED WNW-NW FLOW AREAS THROUGH THE MORNING. MODEL DERIVED SOUNDING BEAR THIS POTENTIAL OUT (ESPECIALLY NAM-BUFR SOUNDINGS WHICH HAVE SOME SUPPORT FROM LATEST ECMWF PROGS)...WITH QUICK UPTICK TO NEAR H75 INVERSION LEVELS...ALL THE WHILE OMEGA MAX BECOMES CENTERED IN PRIME DGZ. HOW WILL ALL THIS PLAY OUT? KINDA ENVISION A PERIOD OF DECENT SNOWS ACROSS NORTHWEST LOWER/EASTERN UPPER MICHIGAN WITH THE FRONTAL PASSAGE...WITH A QUICK TRANSITION TO WNW-NW LAKE ENHANCED SNOWS THROUGH THE REMAINDER OF THE MORNING. ACTIVITY SHOULD BEGIN TO WIND DOWN RATHER QUICKLY DURING THE AFTERNOON...AND ESPECIALLY THURSDAY EVENING...AS MOISTURE RAPIDLY DEPARTS. CIPS ANALOGS FOR THIS EVENT HONING IN ON SOME INTERESTING NUMBERS...WITH IMPACT GUIDANCE SHOWING 6 TO 8 INCH AMOUNTS IN THE TRADITIONAL SNOWBELTS OF BOTH PENINSULAS. QUICK MOVEMENT OF SYSTEM AND SOME LINGERING CONCERN WITH EXACT THERMAL STRUCTURES (SOME GUIDANCE NOT QUITE AS COLD) PREVENTS FROM GOING THIS AGGRESSIVE...BUT WILL GO AHEAD A RAISE INHERITED SNOW AMOUNTS BY AT LEAST AN INCH OR SO...BRINGING DAYTIME ACCUMULATIONS TO 2 TO 3 INCHES IN FAVORED AREAS. IF TRENDS HOLD...MAY EVENTUALLY NEED AN ADVISORY FOR AT LEAST SOME COUNTIES OF NORTHWEST LOWER AND EASTERN UPPER MICHIGAN. SYSTEM EXITS JUST AS QUICK AS IT ARRIVES...WITH ANY LINGERING SNOW SHOWERS COMING TO AN END OVERNIGHT THURSDAY AS MOISTURE DEPARTS AND WAA COMMENCES. CONDITIONS LOOK QUIET AND A TOUCH WARMER TO END THE WORK WEEK AS THE NORTHERN STREAM RELAXATION BEGINS...LETTING HEIGHTS BUILD AND SOUTHWEST WINDS TO DEVELOP ON NORTH SIDE OF SOUTHERN HIGH PRESSURE. NEXT MOISTURE STARVED SYSTEM ARRIVES OVER THE WEEKEND...PERHAPS BRINGING A FEW SNOW SHOWERS ONCE AGAIN SATURDAY INTO SATURDAY NIGHT. TEMPERATURES APPEAR TOO MARGINAL FOR ANY PRE AND POST FRONTAL LAKE ENHANCEMENT. MAIN STORM TRACK CONTINUES TO TREND FURTHER NORTH HEADING INTO NEXT WORK WEEK. PACIFIC AIR STILL APPEARS RATHER AGGRESSIVE...WITH LATEST PROGS SUGGESTING MUCH OF THE NORTHERN CONUS FLOODED BY ABOVE NORMAL TEMPERATURES BY THE MIDDLE OF NEXT WEEK. FORECAST WILL REFLECT THE BEGINNING OF THIS WARM-UP...WITH READINGS RUNNING SEVERAL DEGREES ABOVE NORMAL BY MONDAY AND TUESDAY. AS MENTIONED EARLIER...NOT ENTIRELY SOLD YET ON THIS AGGRESSIVE WARMING...AND STILL PLAUSIBLE FOR BRIEF NORTHERN STREAM FORAYS TO KEEP THE BULK OF THE WARMING OFF TO OUR WEST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1256 PM EST WED JAN 2 2013 MVFR CIGS FOR THE MOST PART THROUGH THE TAF PERIOD. THE EXCEPTION IS LOW END VFR CIGS AT APN THROUGH THIS EVENING. LAKE EFFECT SNOW SHOWERS AND FLURRIES TO CONTINUE THROUGH THIS EVENING AND LIKELY BECOME ENHANCED AT PLN AND MBL LATE TONIGHT INTO THURSDAY MORNING AS AN ALBERTA CLIPPER MOVES BY TO OUR NORTH. && .MARINE... ISSUED AT 449 AM EST WED JAN 2 2013 WINDS WILL GRADUALLY WEAKEN TODAY...BEFORE PICKING BACK UP AGAIN TONIGHT...IN ADVANCE OF AN ALBERTA CLIPPER AND ASSOCIATED COLD FRONT. THE TIGHTEST GRADIENT WILL RESIDE ACROSS THE NW LOWER NEARSHORE...THROUGH THE STRAITS AND INTO NRN LAKE HURON. OVERLAKE INSTABILITY WILL BE DEEPENING WITH THE ABILITY TO TAP ADVISORY LEVEL GUSTS IN THESE AREAS. IN ADDITION...THIS DEEPENING INSTABILITY...AND DEEPER MOISTURE FROM THE CLIPPER...WILL RESULT IN ENHANCED LAKE EFFECT SNOW SHOWERS. THE WINDS WILL BE STRONGEST BEHIND THE COLD FRONT...THURSDAY THROUGH FRIDAY...AND THESE ADVISORIES WILL NOT ONLY NEED TO BE EXTENDED...BUT THE REMAINDER OF THE NEARSHORE WATERS WILL LIKELY NEED ADVISORIES TOO. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR LHZ345>349. LM...SMALL CRAFT ADVISORY UNTIL 1 AM EST FRIDAY FOR LMZ323-342- 344>346. LS...NONE. && $$ UPDATE...AS SYNOPSIS...MB SHORT TERM...SD LONG TERM...MB AVIATION...AS MARINE...SD
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
152 PM EST WED JAN 2 2013 .SYNOPSIS... HIGH PRESSURE CROSSES TONIGHT. CLIPPER LIKE SYSTEM PASSES THURSDAY NIGHT. TWO UPPER SHORT WAVES PASS THIS WEEKEND...FOLLOWED BY HIGH PRESSURE. && .NEAR TERM /THROUGH THURSDAY/... HEATING HAS ALLOWED STRATOCU TO FORM THIS AFTN...MOST PREVALENT ACROSS SE OH AND N WV. LINGERING LLVL MOISTURE UNDER INVERSION PROVIDING FOR A DREARY DAY ACROSS SW VA WITH LOW CIGS AND SOME FOG. WILL ALLOW STRATOCU TO DISSIPATE WITH LOSS OF SUN AS CIRRUS BLOW-OFF RIDING JET FROM SW INVADES TONIGHT. SOME CONCERN WITH LOW STRATUS HANGING TOUGH ACROSS SE OH AND N WV PER RUC SOUNDINGS BUT OTHER MDLS NOT REALLY SHOWING THIS. FOR TEMPS WILL HEDGE THAT CIRRUS IS OPAQUE ENOUGH TO NOT HINDER FALL TOO MUCH. LOOKING AT TEENS AND LWR 20S FOR MOST PART FOR OVERNIGHT LOWS. DRY CONDITIONS PREVAIL TOMORROW WITH A MAINLY SUNNY SKY...SAVE FOR PERHAPS PORTIONS OF SW VA TOWARD DICKENSON CO WHERE LOW CLOUDS MAY LINGER THROUGH THE MORNING. HIGHS REBOUND SOME WITH EVERYONE OUTSIDE OF HIGHER ELEVATIONS IN THE 30S. SOME CLDS MAY SNEAK INTO SE OH TOWARD EVENING FROM AN APPROACHING CLIPPER TYPE FRONT. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... VERY PROGRESSIVE AND DRY PATTERN THIS PERIOD. MODELS HAVE A MOISTURE STARVED SHORT WAVE AND COLD FRONT IN THE NORTHERN STREAM DROPPING RAPIDLY SOUTHEAST ACROSS THE OHIO VALLEY THURSDAY NIGHT AND EARLY FRIDAY. A THERMAL TROUGH IN NORTHWEST FLOW BEHIND THE FRONT PROMPTS SMALL POPS FOR SNOW SHOWERS MAINLY THURSDAY NIGHT...AND MOSTLY IN THE MOUNTAINS...WITH LITTLE IF ANY ACCUMULATIONS. THEN...A QUIET PERIOD WITH MODERATING TEMPERATURES LATER FRIDAY AND SATURDAY AS A LOW AMPLITUDE UPPER RIDGE BUILDS OVER THE AREA. IT WILL BE JUST AFTER THIS PERIOD BEFORE THE NEXT SYSTEM CAN AFFECT US. LOOK FOR BELOW NORMAL TEMPS THURSDAY NIGHT AND FRIDAY BEHIND THE FRONT...MODERATING CLOSE TO NORMAL ON SATURDAY. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... STRONG SHORT WAVE WILL MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY. BUFKIT SOUNDING CONTINUE TO INDICATE SATURATED SFC TO BARELY BELOW MINUS 10C LEVEL...SUGGESTING GOOD CHANCES FOR LIGHT SNOW FOLLOWED BY FREEZING DRIZZLE AS THE SYSTEM PULLS NORTHEAST. NORTHWEST BACKWARDS TRAJECTORIES FROM SUNDAY RETURNS FROM IL AND WI...BRINGING MUCH COLD AIR...CAPABLE TO SQUEEZE LOW LEVEL MOISTURE INTO THE MOUNTAINS...TO PRODUCE LIGHT UPSLOPE SNOW OR FREEZING DRIZZLE PER SHALLOWER MOISTURE IN THE COLUMN WITH NO LAKE CONNECTION BELOW MINUS 10C. THEREFORE...KEPT POPS TO CHANCE FOR NOW ACROSS THE NORTHERN HALF OF OUR CWA THROUGH SATURDAY NIGHT DIMINISHING BY EARLY MONDAY. TWEAKED HPC GUIDANCE FOR TEMPS THROUGH THE PERIOD...ACCOUNTING FOR CLOUD COVER AND GFS H850 COLDER TEMPERATURES. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... HAVE SOME TEMPO GROUPS FOR BKN MVFR ACROSS N TAF SITES THROUGH REMAINDER OF AFTN AND ALSO KBKW. WILL ALLOW THIS TO SCT OUT WITH LOSS OF SUN. THERE IS SOME CONCERN SCT TO BKN STRATOCU MAY LINGER N WV AND SE OH TONIGHT. OTHERWISE...HIGH PRESSURE WILL BRING ABOUT A MAINLY VFR NT TONIGHT...WITH CIRRUS WORKING THROUGH. AND THERE WILL ALSO BE CIRRUS ACROSS THE AREA. VFR CONDITIONS PREVAIL TOMORROW WITH LITTLE IN WAY OF CLDS...SAVE FOR SOME LATE MVFR CIGS ACROSS SE OH WITH APPROACHING CLIPPER TYPE FRONT...PROBABLY JUST BEYOND TAF PERIOD. LIGHT NW FLOW SURFACE AND ALOFT TODAY WILL BECOME LIGHT AND VARIABLE SURFACE AND LIGHT W ALOFT TONIGHT...INCREASING INTO 5 TO 10 KT RANGE TOMORROW AFTN. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z THURSDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: STRATOCU MAY LINGER ACROSS SE OH/N WV TONIGHT. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 CRW CONSISTENCY H H H H H H H M M M M M HTS CONSISTENCY H H H H H H H M M M M M BKW CONSISTENCY M H H H H H H M M M M M EKN CONSISTENCY H H H H H H H M M M M M PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY M M H H H H H M M M M M AFTER 18Z THURSDAY... NO WIDESPREAD IFR CONDITIONS EXPECTED. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...ARJ/JMV/30 NEAR TERM...30 SHORT TERM...JMV LONG TERM...ARJ AVIATION...30
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
116 PM EST WED JAN 2 2013 .SYNOPSIS... HIGH PRESSURE CROSSES TONIGHT. CLIPPER LIKE SYSTEM PASSES THURSDAY NIGHT. TWO UPPER SHORT WAVES PASS THIS WEEKEND...FOLLOWED BY HIGH PRESSURE. && .NEAR TERM /THROUGH THURSDAY/... HEATING HAS ALLOWED STRATOCU TO FORM THIS AFTN...MOST PREVALENT ACROSS SE OH AND N WV. LINGERING LLVL MOISTURE UNDER INVERSION PROVIDING FOR A DREARY DAY ACROSS SW VA WITH LOW CIGS AND SOME FOG. WILL ALLOW STRATOCU TO DISSIPATE WITH LOSS OF SUN AS CIRRUS BLOW-OFF RIDING JET FROM SW INVADES TONIGHT. SOME CONCERN WITH LOW STRATUS HANGING TOUGH ACROSS SE OH AND N WV PER RUC SOUNDINGS BUT OTHER MDLS NOT REALLY SHOWING THIS. FOR TEMPS WILL HEDGE THAT CIRRUS IS OPAQUE ENOUGH TO NOT HINDER FALL TOO MUCH. LOOKING AT TEENS AND LWR 20S FOR MOST PART FOR OVERNIGHT LOWS. DRY CONDITIONS PREVAIL TOMORROW WITH A MAINLY SUNNY SKY...SAVE FOR PERHAPS PORTIONS OF SW VA TOWARD DICKENSON CO WHERE LOW CLOUDS MAY LINGER THROUGH THE MORNING. HIGHS REBOUND SOME WITH EVERYONE OUTSIDE OF HIGHER ELEVATIONS IN THE 30S. SOME CLDS MAY SNEAK INTO SE OH TOWARD EVENING FROM AN APPROACHING CLIPPER TYPE FRONT. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... OVERALL RELATIVELY TRANQUIL WEATHER IN THE SHORT TERM PERIOD. HIGH PRESSURE IN CONTROL FOR START OF SHORT TERM...WITH DRY CONDITIONS...AND SLIGHTLY WARMER TEMPERATURES AS COMPARED TO WEDNESDAY DUE TO INCREASED SOUTHERLY FLOW. CLOUDS WILL INCREASE THROUGHOUT THE DAY HOWEVER...AS A DISTURBANCE/CLIPPER TYPE SYSTEM APPROACHES THE REGION FROM THE NORTH. HAVE CONTINUED TO MAINTAIN A SLIGHT CHANCE OR CHANCE OF PRECIPITATION/IN THE FORM OF SNOW SHOWERS IN THE FORECAST FOR THURSDAY NIGHT/FRIDAY...BUT WITH AN OVERALL LACK OF SIGNIFICANT DEEP MOISTURE...PRECIPITATION WILL BE LIGHT...WITH BEST CHANCES OVER NORTHERN ZONES AND NORTHERN MOUNTAIN ZONES IN THE POST UPSLOPE FLOW. DID ELECT TO RAISE FRIDAY MORNING LOW TEMPS SLIGHTLY FROM PREVIOUS FORECAST DUE TO EXPECTED CLOUD COVER AND WIND ASSOCIATED WITH PASSAGE OF UPPER TROUGH. OTHERWISE...NO MAJOR CHANGES TO PREVIOUS FORECAST. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... MODELS ARE IN FAIRLY AGREEMENT ON THE LONG TERM FORECAST WITH DRIER PARCEL TRAJECTORIES APPROACHES FROM THE CENTRAL PLAINS...TO PROVIDE DRY CONDITIONS INTO SATURDAY. DESPITE DRY CONDITIONS...ABUNDANT CLOUDINESS WILL REMAIN FROM A SOUTHERN STREAM UPPER TROUGH SATURDAY. THE SECOND...BUT STRONGER SHORT WAVE OUT OF PHASE WITH THE AFOREMENTIONED ONE WILL MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY. BUFKIT SOUNDING CONTINUE TO INDICATE SATURATED SFC TO BARELY BELOW MINUS 10C LEVEL...SUGGESTING GOOD CHANCES FOR LIGHT SNOW FOLLOWED BY FREEZING DRIZZLE AS THE SYSTEM PULLS NORTHEAST. NORTHWEST BACKWARDS TRAJECTORIES FROM SUNDAY RETURNS FROM IL AND WI...BRINGING MUCH COLD AIR...CAPABLE TO SQUEEZE LOW LEVEL MOISTURE INTO THE MOUNTAINS...TO PRODUCE LIGHT UPSLOPE SNOW OR FREEZING DRIZZLE PER SHALLOWER MOISTURE IN THE COLUMN WITH NO LAKE CONNECTION BELOW MINUS 10C. THEREFORE...KEPT POPS TO CHANCE FOR NOW ACROSS THE NORTHERN HALF OF OUR CWA THROUGH SATURDAY NIGHT DIMINISHING BY EARLY MONDAY. TWEAKED HPC GUIDANCE FOR TEMPS THROUGH THE PERIOD...ACCOUNTING FOR CLOUD COVER AND GFS H850 COLDER TEMPERATURES. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... HAVE SOME TEMPO GROUPS FOR BKN MVFR ACROSS N TAF SITES THROUGH REMAINDER OF AFTN AND ALSO KBKW. WILL ALLOW THIS TO SCT OUT WITH LOSS OF SUN. THERE IS SOME CONCERN SCT TO BKN STRATOCU MAY LINGER N WV AND SE OH TONIGHT. OTHERWISE...HIGH PRESSURE WILL BRING ABOUT A MAINLY VFR NT TONIGHT...WITH CIRRUS WORKING THROUGH. AND THERE WILL ALSO BE CIRRUS ACROSS THE AREA. VFR CONDITIONS PREVAIL TOMORROW WITH LITTLE IN WAY OF CLDS...SAVE FOR SOME LATE MVFR CIGS ACROSS SE OH WITH APPROACHING CLIPPER TYPE FRONT...PROBABLY JUST BEYOND TAF PERIOD. LIGHT NW FLOW SURFACE AND ALOFT TODAY WILL BECOME LIGHT AND VARIABLE SURFACE AND LIGHT W ALOFT TONIGHT...INCREASING INTO 5 TO 10 KT RANGE TOMORROW AFTN. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z THURSDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: STRATOCU MAY LINGER ACROSS SE OH/N WV TONIGHT. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 CRW CONSISTENCY H H H H H H H M M M M M HTS CONSISTENCY H H H H H H H M M M M M BKW CONSISTENCY M H H H H H H M M M M M EKN CONSISTENCY H H H H H H H M M M M M PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY M M H H H H H M M M M M AFTER 18Z THURSDAY... NO WIDESPREAD IFR CONDITIONS EXPECTED. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...ARJ/JMV/30 NEAR TERM...30 SHORT TERM...SL LONG TERM...ARJ AVIATION...30