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