Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/19/12
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
1021 PM PST SUN DEC 16 2012
.SHORT TERM DISCUSSION...
UPPER LOW IS JUST WEST OF PUGET SOUND WITH TROUGH ALONG THE COAST.
STRONG JET STREAM ENERGY WITH THIS SYSTEM IS PUSHING ACROSS
NORCAL THIS EVENING WITH HEAVY PRECIP DEVELOPING OVER NRN LAKE AND
SHASTA COUNTIES. ALSO STRONG UPSLOPE FLOW IS OVER THE SIERRA IN
WESTERN PLUMAS COUNTY FROM BUCKS LAKE WEST. RUC IS DEPICTING 1 TO
2 FEET IN THIS AREA...WHICH IS RIGHT ON CURRENT FORECAST
ACCUMULATIONS. SNOW LEVELS ARE CURRENTLY NEAR 5200 FEET OVER THE
SIERRA AND 3000 FEET OVER SHASTA COUNTY. TIGHT SURFACE GRADIENT
HAS SET UP OVER THE NRN SACRAMENTO VALLEY AHEAD OF FRONTAL SYSTEM
WITH SUSTAINED WINDS 25 TO 30 MPH GUSTS TO 45 MPH RED BLUFF TO
REDDING HAVE ISSUED A WIND ADVISORY THROUGH 4 AM AND UPDATED WINDS
GRIDS TO REFLECT THIS. EXPECT WINDS TO DIMINISH WITH PASSAGE OF
FRONT AROUND 4 AM. RAIN SHOULD BEGIN IN THE SRN SAC VALLEY AFTER
MIDNIGHT WITH THE BULK OF THE PRECIP BETWEEN 2-6 AM AHEAD OF
FRONTAL BOUNDARY. WINDS COULD ALSO BE BREEZY THROUGH MID MORNING
UNTIL FRONT PASSES...BUT WILL DIMINISH IN THE AFTERNOON.
PREVIOUS DISCUSSION...
SHORT-WAVE RIDGE OVER NORCAL BEGINNING TO GIVE WAY AHEAD OF
STRONGER WAVE THAT WILL MOVE ONSHORE TONIGHT AND SPREAD SOUTH
MONDAY. STRONG WARM ADVECTION CONTINUES TO BRING MOSTLY LIGHT
AMOUNTS OF PRECIP MAINLY TO THE NORTH OF I-80. LOW SNOW LEVELS
REMAIN LOCKED IN NORTH OF REDDING...BUT SOME INCREASE IN SNOW
LEVEL IS EXPECTED LATER TONIGHT AS STRONGER SOUTHERLY FLOW
ATTEMPTS TO SCOUR OUT THE REMAINING COLD AIR.
HEAVIER PRECIP WILL DEVELOP LATER TONIGHT AND SPREAD SOUTH ON
MONDAY AS THE COLD FRONT MOVES THROUGH. TIMING STILL LOOKS LIKE
THE FRONT WILL MAKE IT TO THE SAC AREA AROUND MIDDAY MONDAY.
SCATTERED SHOWERS EXPECTED BEHIND THE FRONT MONDAY AFTERNOON.
CONTINUING UPSLOPE FLOW AND CAA WILL CONTINUE SHOWERS OVER THE
WEST SLOPES OF THE NORTHERN SIERRA MONDAY NIGHT INTO TUESDAY WHILE
THE VALLEY IS EXPECTED TO SEE A DIMINISHING THREAT OF SHOWERS AS
SUBSIDENCE AND NORTHWESTERLY FLOW TAKE HOLD. THE HEAVIEST PERIOD
OF SNOW ALONG I-80 APPEARS TO BE FOCUSED FROM LATER TONIGHT
THROUGH MONDAY WITH WELL OVER A FOOT OF SNOW EXPECTED ABOVE 5000
FEET ELEVATION.
MOSTLY DRY WEATHER EXPECTED WEDNESDAY AS UPPER RIDGE MOVES OVHD
NORCAL...THOUGH INCREASING WARM ADVECTION AHEAD OF THE NEXT
STRONGER SYSTEM LIKELY TO BRING SOME LIGHT PRECIP BACK INTO THE
NORTHERN MOUNTAINS BY THE AFTERNOON.
&&
.EXTENDED DISCUSSION (THURSDAY THROUGH SUNDAY)
MORE PRECIPITATION AND PERIODS OF BREEZY AND GUSTY SOUTHERLY
WINDS AS A BROAD TROUGH OFFSHORE ROTATES SEVERAL SHORTWAVES
THROUGH THE AREA. PRECIPITATION MAY STAY MAINLY NORTH OF INTERSTATE
80 WEDNESDAY NIGHT BUT SPREAD SOUTH DURING THE DAY THURSDAY AS AN
INCH PW PLUME MOVES SOUTH ALONG THE COAST. SNOW LEVELS WILL BE
AROUND 500 FT IN SHASTA COUNTY TO AROUND 2500 FT ALONG THE SIERRA
WEDNESDAY NIGHT INTO THURSDAY MORNING AND RISE TO AROUND 2000 TO
4000 FT BY THURSDAY EVENING. SNOW WILL BE POSSIBLE AROUND REDDING
WEDNESDAY NIGHT INTO THURSDAY MORNING WITH COLD AIR POSSIBLY BEING
TRAPPED IN THE VALLEY. SNOW LEVELS ARE EXPECTED TO RISE TO AROUND
3000 TO 5000 FT ON SATURDAY AND DROP AGAIN TO AROUND 2000 TO 3500
FEET ON SUNDAY. ALTHOUGH THERE IS STILL SOME UNCERTAINTY IN
WEEKEND FORECAST DUE TO VARIABILITY IN THE TIMING OF THE TROUGH
MOVING INLAND. MODELS STILL VARY WITH WHEN THIS TROUGH MAY MOVE
INLAND WITH THE ECMWF MOVING THE TROUGH ONSHORE ON SUNDAY AND THE
18Z OPERATIONAL GFS HOLDING IT OFFSHORE BUT THE GFS ENSEMBLE MEAN
IS IN BETWEEN THE TWO ON TIMING. PRECIPITABLE WATER VALUES AROUND
AN INCH WITH A PLUME OFF THE COAST THURSDAY AND SUNDAY. AROUND AN
INCH TO 3 INCHES OF RAIN ARE POSSIBLE IN THE SACRAMENTO VALLEY AND
POSSIBLY UP TO AN INCH IN THE NORTHERN SAN JOAQUIN VALLEY AND
SEVERAL FEET OF SNOW ARE POSSIBLE OVER THE MOUNTAINS THURSDAY
THROUGH SUNDAY.
&&
.AVIATION...
LOW PRESSURE SYSTEM WILL BRING WIDESPREAD PRECIP ALONG WITH BREEZY
SOUTHERLY WINDS HIS EVENING AS A COLD FRONT APPROACHES. WIND GUSTS
IN THE VALLEY WILL REACH UP TO 26 TO 32 KT TONIGHT.
VFR/MVFR CONDITIONS WILL CDEVELOP FOR SAC METRO TAF SITES AND
KSCK TONIGHT WITH PERIODS OF RAIN. IFR AND LOCAL LIFR CONDITIONS
WILL BE POSSIBLE OVER THE NORTHERN SACRAMENTO VALLEY. SNOW LEVELS
OTHERWISE AROUND 2000 FEET WITH IFR/LIFR CONDITIONS FROM SNOW
CONTINUING THROUGH MONDAY IN THE FOOTHILLS AND MOUNTAINS. SNOW
LEVELS AROUND 1000 TO 2000 FEET OVER SHASTA COUNTY AND TO 4500
FEET OVER THE SIERRA TONIGHT.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL MIDNIGHT PST MONDAY NIGHT BURNEY
BASIN / EASTERN SHASTA COUNTY...WEST SLOPE NORTHERN SIERRA
NEVADA...WESTERN PLUMAS COUNTY/LASSEN PARK.
WIND ADVISORY UNTIL 4 AM PST MONDAY NORTHERN SACRAMENTO VALLEY.
WINTER STORM WARNING UNTIL 4 AM PST MONDAY ABOVE 1500 FEET FOR
THE SHASTA LAKE AREA / NORTHERN SHASTA COUNTY.
&&
$$
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
821 PM MST TUE DEC 18 2012
.UPDATE...SOME MINOR ADJUSTMENTS REGARDING SNOW AMOUNTS BASED OFF
THE LATEST NAM12 00Z RUN. PRIMARILY THE FOOTHILLS OF LARIMER
COUNTY...OTHERWISE THE OVERALL FCST STILL LOOKS GOOD. THERE WAS A
GOOD ENHANCED BAND OF SNOWFALL THAT PRODUCED 1-2 INCHES AROUND
FORT COLLINS EARLIER THIS EVENING...THEN IT SHIFTED TO THE NORTH
AND WEST INTO THE FOOTHILLS. WILL CONTINUE WITH THE TIMING ALREADY
IN THE GRIDS WITH MOST OF THE SNOWFALL DEVELOPING ALONG THE FRONT
RANGE LATE TONIGHT THEN INCREASING WEDNESDAY MORNING. THE LATEST
MDL OUTPUT GENERATED UP TO 12 INCHES POSSIBLE IN THE FOOTHILLS OF
LARIMER COUNTY. ALONG THE URBAN CORRIDOR GENERALLY 2-5 INCHES
STILL LOOKS GOOD...WITH ANOTHER AREA OF HEAVY SNOW (6-8 INCHES) IN
ZONES 48..50 AND 51.
&&
.AVIATION...SUSPECT NORTHEAST TO NORTHERLY WINDS WILL CONTINUE
THROUGH THIS EVENING...THEN NORTHERLIES INCREASING AFTER 06Z.
MDLS STILL GENERATING 2 TO 4 INCHES OF SNOW AT KDEN...WITH AREAS
OF BLOWING SNOW DEVELOPING AFTER 12Z. OVERALL TIMING IN THE TAFS
LOOKS GOOD AT THIS TIME SO ANY CHANGES IN THE UPCOMING TAFS SHOULD
BE MINOR. CONDITIONS SHOULD IMPROVE WEDNESDAY AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 342 PM MST TUE DEC 18 2012/
SHORT TERM...MOUNTAIN WEB CAMS SHOW SNOW HAS DECREASED MOST AREAS
AS FLOW ALOFT BECOMES SOUTHWEST AHEAD OF APPROACHING TROUGH.
ELSEWHERE...MID AND HIGH LEVEL CLOUDS ON THE INCREASE AS MOISTURE
SPREADS INTO REGION. MODELS SIMILAR IN BRINGING TROUGH ACROSS
GREAT BASIN THIS EVENING WITH INCREASING MID LEVEL ASCENT AND
INSTABILITY. SHOULD BEGIN TO SEE SNOW INCREASE ONCE AGAIN...
ESPECIALLY AFTER MIDNIGHT WHEN 700 MB LOW MOVES INTO WESTERN
COLORADO AND FLOW ALOFT BECOMES WESTERLY. SHOULD SEE A GOOD SHOT
OF SNOW WITH THE INCREASING ASCENT AND FAVORABLE LAPSE RATES. WILL
ISSUE AN ADVISORY FOR SNOW FOR THE MOUNTAINS...BEGINNING AT
MIDNIGHT. ACROSS PLAINS...SURFACE LOW TO DEEPEN TONIGHT AHEAD THE
APPROACHING LOW WITH WINDS BECOMING NORTHERLY AFTER 06Z. AIRMASS
TO GRADUALLY MOISTEN AS DEEPER MOISTURE SPREADS INTO AREA.
BEGINNING TO SEE SOME ECHOES ACROSS LARIMER AND NORTHWESTERN WELD
COUNTIES. LATEST MODELS SHOW MOST OF THE SNOW DEVELOPING AFTER
06Z..THOUGH THE RAP HOLDING OFF UNTIL AFTER 09Z WHICH MAY BE A BIT
SLOW. AS WINDS BECOME NORTHERLY...SHOULD SEE SNOW COVERAGE
INCREASE AND BEGIN TO SPREAD SOUTH BY 12Z. UPPER LOW TO MOVE
ACROSS THE STATE DURING THE MORNING WITH GOOD QG VERTICAL
VELOCITIES AND INCREASING LAPSE RATES. LATEST MODELS HAVE BEEN
INDICATING LESS SNOW FOR THE PLAINS...BUT MAY BE OVERDONE GIVEN
THE MID LEVEL ASCENT. A FEW LOCATIONS COULD SEE SNOW FALL RATES OF
1/2 TO 1 INCH PER HOUR DURING THE PERIOD OF GREATEST ASCENT DURING
THE MORNING. WILL UPGRADE THE WINTER STORM WATCH TO A SNOW AND
BLOWING SNOW ADVISORY FOR MUCH OF THE PLAINS. WILL BEGIN THIS
HILITES AT 08Z...MAINLY TO ACCOUNT FOR THE MORNING RUSH. WILL ALSO
ISSUE A SNOW ADVISORY FOR THE FOOTHILLS BEGINNING AT 08Z AS
MODELS SHOW DEEP UPSLOPE TO AROUND 600 MB. ACROSS THE FAR EASTERN
PLAINS...BEST CHANCE FOR SNOW TO BE AROUND 15Z. THOUGH SNOW
AMOUNTS MAY BE A BIT LIGHT...THE GUSTY WINDS WILL PROVIDE FOR
BLIZZARD CONDITIONS FOR ZONES 46..47 AND 49 WITH LIMITED
VISIBILITES. WILL ISSUE A BLIZZARD WARNING FOR THOSE ZONES
BEGINNING AT 15Z. WILL ALSO INCLUDE ZONES 48..50..51 AS WELL AS
41. SOME ROAD CLOSURES WILL CERTAINLY BE POSSIBLE. ACROSS THE
MOUNTAINS...WILL CONTINUE THE ADVISORY THROUGH THE AFTERNOON. SNOW
WILL PROBABLY BE ON THE DECREASE AS MOISTURE AND DYNAMICS
DECREASE. TOTAL SNOW ACCUMULATIONS LOOK TO BE FROM 3 TO 8 INCHES
ACROSS THE PLAINS AND FOOTHILLS...HIGHEST NEAR THE WYOMING
BORDER. ACROSS THE MOUNTAINS...6 TO 14 INCHES CAN BE EXPECTED.
LONG TERM...MODELS SHOW THE UPPER TROUGH AXIS OVER THE EASTERN
BORDER AT 00Z WEDNESDAY EVENING. STRONG NORTHWESTERLY FLOW ALOFT
IS PROGGED WEDNESDAY NIGHT. ON THURSDAY AND THURSDAY NIGHT...AN UPPER
RIDGE IS PROGGED TO MOVE ACROSS COLORADO WITH FAIRLY STRONG WEST-
NORTHWESTERLY FLOW ALOFT. THURSDAY NIGHT AND FRIDAY ARE PROGGED
TO HAVE FAIRLY WEAK ZONAL FLOW ALOFT. BY FRIDAY NIGHT...THE FLOW
ALFOT IS WEST-SOUTHWESTERLY IN DIRECTION. THE QG VERTICAL VELOCITY
FIELDS HAVE DOWNWARD SYNOPTIC SCALE ENERGY PROGGED FOR THE CWA
WEDNESDAY NIGHT INTO THURSDAY EVENING. THE REST OF THE THURSDAY
NIGHT THROUGH FRIDAY NIGHT...THE ENERGY IS BENIGN. THE LOW LEVEL
WIND AND PRESSURE FIELDS SHOW THE BOUNDARY LAYER FLOW TO BECOME
DOWNSLOPING EARLY WEDNESDAY EVENING. BY 06Z WEDNESDAY NIGHT...
WESTERLY WINDS PREVAIL OVER THE MOUNTAINS...FOOTHILLS AND WESTERN
PLAINS...WITH FAIRLY STRONG NORTHWESTERLIES THE FURTHER EAST TO GO
TO THE COLORADO BORDER. DOWNSLOPING IS PROGGED TO CONTINUE
THURSDAY AND FRIDAY...BUT AT LESSER SPEEDS. FOR MOISTURE...THERE
IS STILL SOME OVER THE EASTERN FORECAST AREA EARLY THURSDAY
EVENING...BUT ALL THE MODELS DRY THINGS OUT RAPIDLY AND BY 06Z
WEDNESDAY NIGHT...PRECIPATION SHOULD BE OVER EVERYWHERE. MOISTURE
IS QUITE SPARSE THURSDAY THROUGH FRIDAY NIGHT. THERE IS NO
MEASURABLE PRECIPITATION NOTED ON THE QPF FIELDS WEDNESDAY NIGHT
THROUGH FRIDAY NIGHT...ALL FIVE PERIODS. FOR POPS...WILL DECREASE
EVERYTHING RAPIDLY WEDNESDAY EVENING...THEN NO POPS FROM 06Z
WEDNESDAY NIGHT THROUGH FRIDAY. WILL LINGER SOME BLOWING SNOW OVER
APPROPRIATE AREAS WEDNESDAY NIGHT. AS FAR AS HIGHLIGHTS GO...
WILL GO WITH THE SHORT TERM FORECASTER. FOR TEMPERATURES...
THURSDAY HIGHS ARE 6-9 C WARMER THAN WEDNESDAY`S. MOS GUIDANCE
VALUES MAY BE TO HIGH...ESPECIALLY FIGURING WE WILL LIKELY HAVE A
SNOW COVER IN PLACE OVER MUCH OF THE CWA. FRIDAYS`S HIGH COME UP
ANOTHER 2-4 C FROM THURSDAY`S. FOR THE LATER DAYS...SATURDAY
THROUGH TUESDAY...MODELS HAVE WEST-SOUTHWESTERLY FLOW ALOFT OVER
THE CWA SATURDAY INTO MONDAY. THE ECMWF BRINGS AN UPPER TROUGH
ACROSS LATE MONDAY AND MONDAY NIGHT. THE GFS IS MUCH SLOWER WITH
THE SYSTEM. BOTH MODELS HAVE LITTLE MOISTURE OVER THE WEEKEND. BUT
BY SUNDAY NIGHT...MOISTURE IS ON THE INCREASE. BOTH MODELS DO
SHOW A PRETTY COLD AIRMASS TO MOVE INTO COLORADO WITH THE UPPER
TROUGH MONDAY OR TUESDAY...DEPENDING. THERE IS ALSO UPSLOPE FOR
THE PLAINS AND FOOTHILLS. WILL GO WITH MINOR POPS RIGHT NOW AND
CONTINUE TO WATCH THE EVOLUTION OF THIS FEATURE.
AVIATION...EASTERLY WINDS TO SHIFT TO THE NORTH AROUND 06Z AS A
COLD FRONT MOVES SOUTH ACROSS THE PLAINS. SHOULD SEE CEILINGS
GRADUALLY LOWER...WITH CEILINGS AROUND 6000 FEET POSSIBLE. NOT
EXPECTING SNOW TO DEVELOP UNTIL AFTER 06Z WITH MVFR CONDITIONS
BY 09Z. IFR CONDITIONS TO FROM 12Z TO 19Z DUE TO SNOW AND BLOWING
SNOW AS WELL AS LOW CEILINGS. SNOW TO DECREASE AFTER 19Z BUT GUSTY
WINDS TO CONTINUE. MVFR CONDITIONS TO PREVAIL WITH OCCASIONAL IFR
CONDITIONS. TOTAL SNOW ACCUMULATIONS OF 2 TO 4 INCHES
EXPECTED...MAINLY DURING THE 12Z TO 18Z TIME FRAME.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
BLIZZARD WARNING FROM 8 AM TO 8 PM MST WEDNESDAY FOR COZ041-
046>051.
WINTER WEATHER ADVISORY FROM 3 AM TO 5 PM MST WEDNESDAY FOR
COZ035-036-038>040-042>045.
WINTER WEATHER ADVISORY UNTIL 5 PM MST WEDNESDAY FOR COZ031-033-
034.
&&
$$
SHORT TERM...COOPER
LONG TERM....RJK
AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
547 PM MST TUE DEC 18 2012
.UPDATE...
ISSUED AT 547 PM MST TUE DEC 18 2012
UPGRADED THE WINTER WEATHER ADVISORY IN THE EASTERN UINTA BASIN
TO A WINTER STORM WARNING. SPOTTERS HAVE REPORTED FROM 4 TO 7
INCHES ALREADY ON THE GROUND. SNOW WILL CONTINUE THIS EVENING
BEFORE TAPERING OFF LATER TONIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 218 PM MST TUE DEC 18 2012
THIS LATE AFTERNOON THE FORECAST AREA IS DIVIDED INTO TWO REGIMES
DIVIDED BY THE COLD FRONT LAYING ALONG THE ROAN-TAVAPUTS PLATEAU
INTO THE FLATTOPS. ALONG AND NORTH OF THE FRONT...HEAVY SNOW HAS
BEEN FALLING. STATE PATROL REPORTS AROUND 6 INCHES IN CRAIG THOUGH
ONLY HALF AND INCH IN VERNAL. CROSHO AND BUFFALO PARK SNOTELS REPORT 15
INCHES OF NEW SNOW. SOUTH OF THE FRONT SNOWFALL HAS BEEN MUCH MORE
SKETCHY...MAINLY ALONG SW FACING SLOPES.
A STRONG WEST TO EAST ORIENTED JET STREAK ALONG THE WYOMING
BORDER THIS MORNING HAS LIFTED OFF TO THE NE TODAY. IN RESPONSE
THE MID-UPPER FLOW HAS BACKED TO SSW TODAY PRODUCING WARM
ADVECTION. THIS WARM OVER-RUNNING HAS HELPED TO PRODUCE THE HEAVY
SNOWFALL ALONG THE STATIONARY FRONT. SOUTH OF THE
FRONT...AFTERNOON SURFACE TEMPERATURES CLIMBED SEVERAL DEGREES
ABOVE GUIDANCE. STRONG ISENTROPIC UPGLIDE WILL CONTINUE INTO THIS
EVENING. THIS STABILIZING PATTERN CAN BE SEEN ON RADAR WITH MTN
WAVE BANDING SEEN TO THE NORTH OF THE RADAR TRANSMITTER.
WET BULB ZERO AND 700MB TEMPS SUPPORT SNOW DOWN TO 4500FT SO ANY
SHOWERS WILL QUICKLY TURN TO SNOW.
THE UPPER LEVEL TROUGH MOTION...THROUGH THE GREAT BASIN TONIGHT...
HAS GOOD MODEL CONTINUITY. YET THE 18Z NAM AND RAP BOTH SUPPORT A
LATER FRONTAL ADVANCE HOWEVER...NOW INTO THE I-70 CORRIDOR AROUND
MIDNIGHT TONIGHT. THIS PUTS THE CENTRAL VALLEY WARNINGS IN DOUBT
BUT DOES NOT REMOVE THE POTENTIAL TO GET UP TO 6 INCHES OF
SNOWFALL THERE. BASED ON THIS AND IN COORDINATION WITH THE SLC
OFFICE... HAVE KEPT THE WARNINGS IN PLACE AND SLOWED THE WORDING
TO EMPHASIZE THE PERIOD BETWEEN MIGHT AND SUNRISE.
THE SOUTHERN ZONES TOO WILL SEE IMPRESSIVE FRONTAL FORCING AFTER
MIDNIGHT INTO WEDNESDAY MORNING. IN THE COLD SECTOR OF THE STORM
LATE TONIGHT THROUGH WEDNESDAY...700MB TEMPERATURES WILL DROP
RIGHT THROUGH THE DENDRITIC CRYSTAL GROWTH REGIME TO -17C BY
WEDNESDAY AFTERNOON. THIS WILL VERY EFFICIENTLY EEK OUT ALL
AVAILABLE MOISTURE. ONLY NW-FACING SLOPES WILL CONTINUE THROUGH
WEDNESDAY AFTERNOON WITH ALL SHOWERS SHUTTING DOWN BY SUNSET. A
VERY COLD NIGHT IS IN STORE FOR WEDNESDAY NIGHT.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 430 AM
MST TUE DEC 18 2012
DRIER NORTHWESTERLY FLOW ALOFT OVERHEAD WEDNESDAY NIGHT AS THE STORM
SYSTEM CONTINUES TO MOVE EAST. A RIDGE OF HIGH PRESSURE WILL MOVE
EAST OVER THE REGION AND REMAIN DOMINATE DURING THE END OF THE WEEK.
WITH SNOW ON THE GROUND...THE COLD AIR MASS BEHIND THE FRONT AND HIGH
PRESSURE EXPECT VALLEY INVERSIONS. TEMPERATURES SHOULD REMAIN COLD
IN THE VALLEYS. THEREFORE WENT BELOW GUIDANCE FOR THESE LOCATIONS.
THE COLDEST MORNING SHOULD BE THURSDAY WHICH SHOULD ALSO BE THE
COLDEST OF THE SEASON. BY THE END OF THE WEEK TEMPERATURES SHOULD BE
MODIFIED SLIGHTLY BUT THIS WILL BE A SLOW PROCESS DUE TO THE
PREVIOUSLY MENTIONED RIDGE OF HIGH PRESSURE.
THE RIDGE WILL SLIDE EASTWARD ALLOWING THE NEXT STORM SYSTEM INTO
THE AREA BY MONDAY ALTHOUGH THE TIMING AND PLACEMENT VARIES BETWEEN
MODELS. INCREASED THE PRECIPITATION FORECAST SLIGHTLY TO HIGHLIGHT
THAT A STORM IS ON THE HORIZON. THAT SAID THERE ARE MANY VARIABLES
STILL NOT WORKED OUT YET SO MUCH UNCERTAINTY WITH TIMING AND
STRENGTH.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 1030 AM MST TUE DEC 18 2012
WIDESPREAD MODERATE TO STRONG MECHANICAL TURBULENCE EXPECTED THIS
EVENING ALONG AND NORTH OF AREA RIDGES AND MTNS. WRN COLORADO TAF
SITES...DETERIORATING CONDITIONS TONIGHT WITH LOWERING CIGS AFTER
03Z...BECOMING WIDESPREAD IFR FOR ALL TAF SITES AFTER 06Z.
WIDESPREAD 1 1/2SM -SN BR CIGS VV002 IS EXPECTED INTO WEDNESDAY MORNING.
AREAS OF MODERATE SN OVER NW COLORADO TODAY WILL SPREAD
SOUTHWARD OVERNIGHT.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING UNTIL NOON MST WEDNESDAY FOR COZ003-006>008-
011-014-020-022-023.
WINTER STORM WARNING UNTIL 6 AM MST WEDNESDAY FOR COZ001-002.
WINTER STORM WARNING UNTIL 6 PM MST WEDNESDAY FOR COZ004-005-009-
010-012-013-017>019.
WINTER WEATHER ADVISORY UNTIL NOON MST WEDNESDAY FOR COZ021.
UT...WINTER STORM WARNING UNTIL NOON MST WEDNESDAY FOR UTZ025.
WINTER STORM WARNING UNTIL 6 AM MST WEDNESDAY FOR UTZ023-024.
WINTER STORM WARNING UNTIL 8 AM MST WEDNESDAY FOR UTZ027.
WINTER WEATHER ADVISORY UNTIL 8 AM MST WEDNESDAY FOR UTZ029.
WINTER STORM WARNING UNTIL 6 PM MST WEDNESDAY FOR UTZ028.
&&
$$
UPDATE...NL
SHORT TERM...JOE
LONG TERM...AS
AVIATION...PF/JOE
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
334 PM MST MON DEC 17 2012
.SHORT TERM...WEB CAMS SHOWING SNOW ACROSS MOUNTAINS
CONTINUING...THOUGH A BIT IMPROVEMENT IN THE LAST FEW HOURS. ALSO
SOME GUSTS AROUND 50 MPH ALONG THE DIVIDE...WHICH HAS BEEN
CREATING AREAS OF BLOWING AND DRIFITING SNOW. LATEST SNOWTELL OBS
SUGGESTING ABOUT 6 INCHES OF SNOW HAD FALLEN ACROSS ZONE 31 IN THE
LAST 6 HOURS...WITH PERHAPS 2 TO 4 INCHES FOR ZONES 33 AND 34.
ACROSS FOOTHILLS AND ALONG URBAN CORRIDOR...WESTERLY WINDS GUSTING
IN THE 30-40 MPH RANGE MOST AREAS. STRONG PACIFIC JET STILL
EXPECTED TO MOVE ACROSS NORTHERN COLORADO DURING THE EVENING AND
OVERNIGHT WITH STRONGER WINDS LOWERING TO NEAR MOUNTAIN TOP. MODEL
CROSS SECTIONS INDICATING INCREASING LAPSE RATES ALONG WITH MID
LEVEL ASCENT. SHOULD SEE MOUNTAIN SNOW BEGIN TO INCREASE AGAIN
DURING THE EVENING AS THE LIFT INCREASES. LOCAL SNOW MODEL STILL
YIELDING ROUGHLY 5-10 INCHES ACROSS ZONE 31 TONIGHT...WITH AROUND
4-8 INCHES FOR ZONES 33 AND 34. THIS LOOKS REASONABLE BUT MAY NEED
TO ADD A FEW INCHES FOR THE DYNAMICS. FEEL CURRENT WARNING FOR
ZONE 31 AND ADVISORY FOR 33 STILL ON TRACK. BUT WILL ALSO INCLUDE
ZONE 34 IN THE ADVISORY...THOUGH AMOUNTS MAY NOT MEET CRITERIA
THERE WILL BE SUFFICIENT BLOWING SNOW. ACROSS PLAINS SHOULD SEE
WINDS BEGIN TO DECOUPLE THOUGH WILL REMAIN A BIT GUSTY NEAR THE
FOOTHILLS. LATEST RUC SHOWS SOME LIGHT PRECIP ACROSS ZONE 38 THIS
EVENING...STILL LOOKS REASONABLE WITH THE APPROACHING LIFT. ON
TUESDAY...FLOW ALOFT WEAKENS A BIT AS THE JET CORE HEADS EAST AND
BECOMES MORE SOUTHWEST AS AN UPPER TROUGH APPROACHES THE GREAT
BASIN. WILL STILL BE A BIT GUSTY ACROSS THE RIDGES. SOUTHWEST
FLOW NOT FAVORABLE FOR DECENT MOUNTAIN SNOWFALL. MID LEVEL QG
ACENT ALSO DECREASES. WOULD EXPECT SNOW TO CONTINUE WITH FAIRLY
GOOD MOISTURE...BUT SHOULD BE LIGHT. WILL NOT EXTEND HILITES
BEYOND 12Z. ACROSS PLAINS...SURFACE WINDS TO BECOME EASTERLY WITH
THE DEVELOPMENT OF AN ANTICYCLONE. LATEST GFS AND ECMWF SHOWS SOME
LIGHT QPF DURING THE AFTERNOON...MAY BE A BIT OVERDONE AS LOW
LEVEL STILL LOOK DRY.
.LONG TERM...MODELS CONTINUE TO ADVERTISE A SIGNIFICANT WINTER
WEATHER EVENT ACROSS THE FORECAST AREA ON WEDNESDAY. FROM TUESDAY
EVENING THROUGH WEDNESDAY EVENING AN UPPER TROUGH WILL BE MOVING
OVER THE STATE WHILE A SURFACE LOW OVER SOUTHEAST COLORADO
UNDERGOES STRONG CYCLOGENESIS. A STRONG COLD FRONT WILL MOVE OVER
NORTHERN COLORADO...INCLUDING THE MOUNTAINS...TUESDAY EVENING.
UPSLOPE WINDS WILL THEN CONTINUE THROUGH THE PRE-DAWN HOURS AND
STRENGTHEN THROUGH THE DAY WEDNESDAY. THE UPPER TROUGH WILL
CONTAIN PLENTY OF DYNAMICS ACCORDING TO THE Q-G DIAGNOSTICS
PACKAGE. THE PRESENCE OF THE STRONG UPPER LEVEL JET OVER THE PAST
FEW DAYS MAKE THE MODEL SOLUTIONS VERY BELIEVABLE. THE NAM QPF
AMOUNTS ARE A FAIR AMOUNT HIGHER THAN THE GFS AND ECMWF SOLUTIONS
CONCERNING HOW MUCH SNOW WE GET ON WEDNESDAY. ALL MODELS AGREE
QUITE A BIT OF WIND DEVELOPING. WITH THE THREAT OF SIGNIFICANT
BLOWING SNOW BECAUSE OF THE WIND...WILL ISSUE A WINTER STORM WATCH
ACROSS THE PLAINS. SNOW AMOUNTS OF 3 TO 6 INCHES WILL BE TOO LIGHT
IF THE NAM IS RIGHT. WIND GUSTS OF 25 TO 40 MPH MIGHT BE COMMON AT
THE HEIGHT OF THE STORM. PERIODS OF SNOW WILL BE ONGOING IN THE
MOUNTAINS DUE TO THE DYNAMICS OVER THE STATE.
THE UPPER TROUGH WILL BE MOVING EAST OF COLORADO BY WEDNESDAY
EVENING WHICH WILL BRING A RAPID END TO THE SNOW EVENT. LINGERING
SHOWERS IN THE EVENING WILL COME TO AN END OVERNIGHT. FOR THE
PERIOD THURSDAY THROUGH SUNDAY...STRONG UPPER RIDGING WILL BE OVER
THE STATE WITH DRY WEATHER FROM THE MOUNTAINS EASTWARD WITH
TEMPERATURES TRENDING TOWARD SEASONAL NORMALS.
EARLY NEXT WEEK LOOKS LIKE ANOTHER TROUGH MAY BE APPROACHING THE
STATE IF THE ECMWF IS CORRECT. FOR THE TIME BEING WILL JUST
MENTION AN INCREASING CHANCE OF SNOW IN THE MOUNTAINS AS THE STATE
COMES UNDER THE SOUTHWESTERLY FLOW AHEAD OF THE TROUGH.
&&
.AVIATION...WESTERLY WINDS TO CONTINUE ACROSS THE DENVER
AREA THROUGH 02Z...WITH SOME GUSTS TO TO 35 KTS. WINDS TO DECREASE
AT DEN AND APA AND BECOME SOUTHWESTERLY DURING THE EVENING BUT
SHOULD REMAIN WESTERLY AND GUSTY AT BJC. AFTER 15Z TUESDAY...
MODELS SHOW THE DEVELOPMENT OF AN ANTICYCLONE IN THE DENVER
AREA...WITH WIND BECOMING EASTERLY. VFR TO CONTINUE WITH NO
PRECIPITATION EXPECTED.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY
AFTERNOON FOR COZ038>051.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR COZ034.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR COZ033.
WINTER STORM WARNING UNTIL 5 AM MST TUESDAY FOR COZ031.
&&
$$
SHORT TERM...D-L
LONG TERM....DANKERS
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1007 AM MST MON DEC 17 2012
.UPDATE...
&&
.SHORT TERM...WEB CAMS ACROSS MOUNTAINS SHOWING SNOW CONTINUING...
WITH SOME SIGNS OF INCREASING IN THE STEAMBOAT AREA AS WELL AS
ACROSS THE HIGHER ELEVATIONS OF GRAND...BOULDER AND LARIMER
COUNTIES. WILL MAINTAIN THE CURRENT HILITES FOR ZONES 31 AND 33
THOUGH NOT EXPECTING MUCH ACCUMULATION THROUGH THIS AFTERNOON.
WINDS HAVE ALSO BEEN STEADILY INCREASING AS CROSS MOUNTAIN
PRESSURE GRADIENT INCREASES...WITH 1500M GJT-DEN GRADIENT AT 9.53
MB. BOTH RUC AND NAM CONTINUE TO SHOW WINDS ACROSS MOUNTAINS AND
FOOTHILLS INCREASING THROUGH THE DAY AS NOSE OF STRONG PACIFIC JET
MOVES INTO NORTHWEST COLORADO. RUC CROSS SECTIONS INDICATE 50 KTS
OF CROSS MOUNTAIN FLOW MOVING DOWN THE LEE SLOPES OF THE FOOTHILLS
BY 20Z. SHOULD CONTINUE TO SEE AN INCREASE IN WINDS OVER THE
MOUNTAINS AND ALONG THE FOOTHILLS WITH WINDS SPREADING ACROSS THE
PLAINS. AT THIS TIME...NOT EXPECTING WINDS REACHING HIGH WIND
CRITERIA AS LAPSE RATES BEGIN TO INCREASE AND LIMIT STABILITY.
OVERALL...CURRENT FORECASTS STILL SEEM ON TRACK. LATEST RAP SHOWS
SOME LIGHT QPF ACROSS NORTHERN PLAINS AFTER 20Z IN AREA OF FAVORED
LIFT ASSOCIATED WITH THE APPROACHING JET. MAY NEED TO INCLUDE THE
FAR NORTHEAST CORNER.
.AVIATION...GUSTY WESTERLY WINDS TO CONTINUE TO BE THE MAIN
CONCERN ACROSS THE DENVER AREA THIS AFTERNOON AND EVENING. CURRENT
TAF TREND STILL SEEM ON TRACK WITH GUSTS TO 40 KTS POSSIBLE. MAY
NEED TO KEEP MORE OF A SOUTHWEST COMPONENT FOR A FEW HOURS PER
RUC AND NAM.
&&
.PREV DISCUSSION... /ISSUED 456 AM MST MON DEC 17 2012/
SHORT TERM...WE/RE SETTING UP FOR A VERY WINDY 12-18HRS IN THE
HIGH COUNTRY AND FRONT RANGE FOOTHILLS. ALREADY SEEING WLY SFC
WINDS GUSTING IN THE 50-55 MPH RANGE AT A NUMBER OF HIGH MTN
MONITORING SITE. THE CROSS MTN PRES GRADIENT CONTINUES TO
INCREASE WITH A 8MB DEN-GJT GRADIENT AT THIS HOUR...AND THE RUC
WAS ALSO INDICATING A STRENGTHENING MTN TOP STABLE LAYER WITH
SLIGHT WARMING ALOFT. IN ADDITION...BOTH THE RUC AND NAM SHOW A
LEE SIDE MTN WAVE AMPLYING THROUGH THE DAY. AS THIS IS GOING
ON...MODELS SHOW THE NOSE OF A POWERFUL PACIFIC JET REACHING
NWRN COLORADO THIS AFTERNOON...AND TRAVERSING THE NRN HALF OF
THE STATE OVERNIGHT WITH THE ARRIVAL OF EVEN STRONGER WINDS AT ITS
CORE. ITS OVERNIGHT WHEN MODELS SHOW THESE ESPLY STRONG WINDS
LOWERING IN ALTITUDE TO NEAR MTN TOP LEVEL. NOT OUT OF THE
QUESTION THAT WINDS ABOVE TIMBERLINE COULD EXCEED 70 MPH CREATING
SERIOUS WHITEOUT CONDITIONS. HOW FAR SOUTH MIGHT WE EXPECT ALL
THIS. AT THIS TIME IT WOULD APPEAR MTN AREAS ROUGHLY ALONG AND
NORTH OF INTERSTATE 70 WILL BE GROUND ZERO. MTN ZONE 31 IS
PRESENTLY UNDER A WINTER STORM WARNING..AND NRN MTN ZONE 33 A
WINTER WEATHER ADVISORY. NO CHANGES TO CURRENT HIGHLIGHTS AT THIS
TIME EVEN THOUGH FEW N-CENTRAL MTN LOCALES REPORTING ACCUMULATING
SNOWFALL ATTM...WITH ONLY LIGHT SNOWFALL UP AT EISENHOWER TUNNEL
VIA CDOT MTN CAMS. DO NOT SEE MUCH IN THE WAY OF SNOW
ACCUMULATION IN THE HIGH COUNTRY THIS MORNING AND POSSIBLY INTO
EARLY AFTERNOON WITH POOR LAPSE RATES OVER THE AREA. ITS LATE
THIS AFTERNOON AS WINDS INCREASE THAT THE INSTABILITY INCREASES
AND MOISTURE DEEPENS ACCORDING TO MODEL SOUNDINGS AND CROSS
SECTIONS. BUT ITS OVERNIGHT WHEN EVERYTHING COMES TOGETHER FOR A
NASTY SITUATION IN THE HIGH COUNTRY. THE WINTER WEATHER ADVISORY
FOR ZONE 34 MAY NEED TO BE UPGRADED TO A STORM WARNING OR POSSIBLY
A BLIZZARD WARNING SHOULD WINDS AND SNOWFALL BECOME GREATER THAN
NOW EXPECTED. MAY ALSO NEED TO ADD MTN ZONE 34 TO HIGHLIGHTS IF
THE CORE OF THE JET SAGS FARTHER SOUTH.
MEANWHILE...ON THE PLAINS WESTERLY FLOW OFF THE FRONT RANGE WILL
WARM TEMPS WELL ABOVE AVERAGE TODAY...PARTICULARLY IN THE WINDIER
AREA ALONG THE BASE OF THE FOOTHILLS. COULD SEE GUSTS IN THE 30-40
MPH IN THE CHINOOK ZONE WEST OF I-25 AND 15-30 MPH FARTHER OUT
ACROSS THE PLAINS. SFC WINDS ON THE PLAINS EXPECTED TO DECOUPLE
FROM THE 130+KT WINDS ALOFT THIS EVENING. PLAINS WILL ALSO REMAIN
DRY THROUGH ALL THIS...EXCEPT PERHAPS UP ALONG THE WYOMING BORDER
WHERE A FEW SNOW SHWRS MAY MOVE OFF THE FOOTHILLS OVERNIGHT.
LONG TERM...MAIN CONCERN WILL BE CONTINUED WIND AND SNOW IN THE
MOUNTAINS ON TUESDAY...AND THEN DEVELOPING SNOW AND COLDER
TEMPERATURES ON THE PLAINS LATE TUESDAY NIGHT AND WEDNESDAY. AS
FORECAST CONFIDENCE INCREASES WITH CONSISTENT MODEL SOLUTIONS IT
APPEARS THIS WILL BE THE FIRST WIDESPREAD SNOW EVENT SINCE EARLIER
THIS FALL. FOR TUESDAY..MOISTURE DEPTH IS RATHER SHALLOW IN THE
MOUNTAINS SO EXPECT MAINLY LIGHT SNOWFALL DURING THE DAY. MOISTURE
DEPTH INCREASES LATE TUESDAY AND TUESDAY NIGHT AS THE MAIN UPPER
TROF APPROACHES COLORADO AND THEN MOVES ACROSS THE STATE ON
WEDNESDAY AS A STRONG OPEN WAVE. QG FIELDS SHOWING FAIRLY STRONG
UPWARD ASCENT AS THE TROF PASSES BY. SURFACE LOW PRESSURE WILL BE
DEEPENING TUESDAY NIGHT ACROSS SOUTHEAST COLORADO WHICH WILL
INCREASE WINDS FROM THE NORTH AND NORTHEAST AND AIRMASS SATURATES.
COMPILATION OF MODELS SHOWING ANYWHERE FROM 2-6 INCHES OF SNOW
OVER THE PLAINS BY LATE WEDNESDAY GIVEN A PERIOD OF 8-12 HOURS OF
SNOWFALL. GIVEN THE AMOUNT OF WINDS WOULD EXPECT WINTER WEATHER
ADVISORIES MAY BE NEEDED AT SOME POINT ON THE PLAINS BUT STILL
HAVE TO TIME TO NARROW DOWN THE DETAILS.
THE SNOW WILL DECREASE WEDNESDAY AFTERNOON WITH GRADUAL CLEARING
EXPECTED WEDNESDAY NIGHT ACROSS THE STATE. CROSS SECTIONS
INDICATING STRONGER WINDS DEVELOPING AGAIN BEHIND THE TROF OVER
THE MOUNTAINS AND EAST SLOPES. THIS MAY RESULT IN ISSUES WITH
BLOWING SNOW OVER THE FOOTHILLS AND ADJACENT PLAINS. LOOKING FOR A
DRY PERIOD WITH MODERATING TEMPERATURES FOR THURSDAY THROUGH THE
WEEKEND. AS A SIDE NOTE...LONG RANGE MODELS ARE SHOWING ANOTHER
POSSIBLE STORM DEVELOPING AROUND CHRISTMAS GIVE OR TAKE A DAY ON
EITHER SIDE. STILL A LOT OF VARYING SOLUTIONS SO WON`T GET TOO
EXCITED YET.
AVIATION...WINDS MAIN CONCERN IN THE DENVER AREA TODAY. BJC NEAR
THE FOOTHILLS ALREADY SEEING PERIODIC WEST WINDS OF 20-25KTS.
WINDS EVEN STRONGER THAN THIS LIKELY TO BECOME MORE PERSIST AT
BJC AS THE MORNING PROGRESSES WITH WLY GUSTS APCHG 45KTS BY
AFTERNOON. SLY WINDS AT DIA AND APA ALSO EXPECTED TO PICK UP IN
THE NEXT FEW HRS AS THEY SHIFT TO A WESTERLY COMPONENT. COULD SEE
GUSTS IN THE 20-35KTS AT BOTH AIRPORTS BY MID TO LATE
AFTERNOON...AND THROUGHOUT THE AFTERNOON. NO PRECIP AT THIS
TIME...SO VFR CIGS AND VSBYS. BY NIGHTFALL SHOULD SEE A STEADY
DROP OF IN WINDS AT DIA AND APA...BUT GUSTY WLY WINDS LIKELY TO
CONTINUE AT BJC FOR MUCH OF THE EVENING.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 5 AM MST TUESDAY FOR COZ031.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR COZ033.
&&
$$
SHORT TERM...D-L
LONG TERM....ENTREKIN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
456 AM MST MON DEC 17 2012
.SHORT TERM...WE/RE SETTING UP FOR A VERY WINDY 12-18HRS IN THE
HIGH COUNTRY AND FRONT RANGE FOOTHILLS. ALREADY SEEING WLY SFC
WINDS GUSTING IN THE 50-55 MPH RANGE AT A NUMBER OF HIGH MTN
MONITORING SITE. THE CROSS MTN PRES GRADIENT CONTINUES TO
INCREASE WITH A 8MB DEN-GJT GRADIENT AT THIS HOUR...AND THE RUC
WAS ALSO INDICATING A STRENGTHENING MTN TOP STABLE LAYER WITH
SLIGHT WARMING ALOFT. IN ADDITION...BOTH THE RUC AND NAM SHOW A
LEE SIDE MTN WAVE AMPLYING THROUGH THE DAY. AS THIS IS GOING
ON...MODELS SHOW THE NOSE OF A POWERFUL PACIFIC JET REACHING
NWRN COLORADO THIS AFTERNOON...AND TRAVERSING THE NRN HALF OF
THE STATE OVERNIGHT WITH THE ARRIVAL OF EVEN STRONGER WINDS AT ITS
CORE. ITS OVERNIGHT WHEN MODELS SHOW THESE ESPLY STRONG WINDS
LOWERING IN ALTITUDE TO NEAR MTN TOP LEVEL. NOT OUT OF THE
QUESTION THAT WINDS ABOVE TIMBERLINE COULD EXCEED 70 MPH CREATING
SERIOUS WHITEOUT CONDITIONS. HOW FAR SOUTH MIGHT WE EXPECT ALL
THIS. AT THIS TIME IT WOULD APPEAR MTN AREAS ROUGHLY ALONG AND
NORTH OF INTERSTATE 70 WILL BE GROUND ZERO. MTN ZONE 31 IS
PRESENTLY UNDER A WINTER STORM WARNING..AND NRN MTN ZONE 33 A
WINTER WEATHER ADVISORY. NO CHANGES TO CURRENT HIGHLIGHTS AT THIS
TIME EVEN THOUGH FEW N-CENTRAL MTN LOCALES REPORTING ACCUMULATING
SNOWFALL ATTM...WITH ONLY LIGHT SNOWFALL UP AT EISENHOWER TUNNEL
VIA CDOT MTN CAMS. DO NOT SEE MUCH IN THE WAY OF SNOW
ACCUMULATION IN THE HIGH COUNTRY THIS MORNING AND POSSIBLY INTO
EARLY AFTERNOON WITH POOR LAPSE RATES OVER THE AREA. ITS LATE
THIS AFTERNOON AS WINDS INCREASE THAT THE INSTABILITY INCREASES
AND MOISTURE DEEPENS ACCORDING TO MODEL SOUNDINGS AND CROSS
SECTIONS. BUT ITS OVERNIGHT WHEN EVERYTHING COMES TOGETHER FOR A
NASTY SITUATION IN THE HIGH COUNTRY. THE WINTER WEATHER ADVISORY
FOR ZONE 34 MAY NEED TO BE UPGRADED TO A STORM WARNING OR POSSIBLY
A BLIZZARD WARNING SHOULD WINDS AND SNOWFALL BECOME GREATER THAN
NOW EXPECTED. MAY ALSO NEED TO ADD MTN ZONE 34 TO HIGHLIGHTS IF
THE CORE OF THE JET SAGS FARTHER SOUTH.
MEANWHILE...ON THE PLAINS WESTERLY FLOW OFF THE FRONT RANGE WILL
WARM TEMPS WELL ABOVE AVERAGE TODAY...PARTICULARLY IN THE WINDIER
AREA ALONG THE BASE OF THE FOOTHILLS. COULD SEE GUSTS IN THE 30-40
MPH IN THE CHINOOK ZONE WEST OF I-25 AND 15-30 MPH FARTHER OUT
ACROSS THE PLAINS. SFC WINDS ON THE PLAINS EXPECTED TO DECOUPLE
FROM THE 130+KT WINDS ALOFT THIS EVENING. PLAINS WILL ALSO REMAIN
DRY THROUGH ALL THIS...EXCEPT PERHAPS UP ALONG THE WYOMING BORDER
WHERE A FEW SNOW SHWRS MAY MOVE OFF THE FOOTHILLS OVERNIGHT.
.LONG TERM...MAIN CONCERN WILL BE CONTINUED WIND AND SNOW IN THE
MOUNTAINS ON TUESDAY...AND THEN DEVELOPING SNOW AND COLDER
TEMPERATURES ON THE PLAINS LATE TUESDAY NIGHT AND WEDNESDAY. AS
FORECAST CONFIDENCE INCREASES WITH CONSISTENT MODEL SOLUTIONS IT
APPEARS THIS WILL BE THE FIRST WIDESPREAD SNOW EVENT SINCE EARLIER
THIS FALL. FOR TUESDAY..MOISTURE DEPTH IS RATHER SHALLOW IN THE
MOUNTAINS SO EXPECT MAINLY LIGHT SNOWFALL DURING THE DAY. MOISTURE
DEPTH INCREASES LATE TUESDAY AND TUESDAY NIGHT AS THE MAIN UPPER
TROF APPROACHES COLORADO AND THEN MOVES ACROSS THE STATE ON
WEDNESDAY AS A STRONG OPEN WAVE. QG FIELDS SHOWING FAIRLY STRONG
UPWARD ASCENT AS THE TROF PASSES BY. SURFACE LOW PRESSURE WILL BE
DEEPENING TUESDAY NIGHT ACROSS SOUTHEAST COLORADO WHICH WILL
INCREASE WINDS FROM THE NORTH AND NORTHEAST AND AIRMASS SATURATES.
COMPILATION OF MODELS SHOWING ANYWHERE FROM 2-6 INCHES OF SNOW
OVER THE PLAINS BY LATE WEDNESDAY GIVEN A PERIOD OF 8-12 HOURS OF
SNOWFALL. GIVEN THE AMOUNT OF WINDS WOULD EXPECT WINTER WEATHER
ADVISORIES MAY BE NEEDED AT SOME POINT ON THE PLAINS BUT STILL
HAVE TO TIME TO NARROW DOWN THE DETAILS.
THE SNOW WILL DECREASE WEDNESDAY AFTERNOON WITH GRADUAL CLEARING
EXPECTED WEDNESDAY NIGHT ACROSS THE STATE. CROSS SECTIONS
INDICATING STRONGER WINDS DEVELOPING AGAIN BEHIND THE TROF OVER
THE MOUNTAINS AND EAST SLOPES. THIS MAY RESULT IN ISSUES WITH
BLOWING SNOW OVER THE FOOTHILLS AND ADJACENT PLAINS. LOOKING FOR A
DRY PERIOD WITH MODERATING TEMPERATURES FOR THURSDAY THROUGH THE
WEEKEND. AS A SIDE NOTE...LONG RANGE MODELS ARE SHOWING ANOTHER
POSSIBLE STORM DEVELOPING AROUND CHRISTMAS GIVE OR TAKE A DAY ON
EITHER SIDE. STILL A LOT OF VARYING SOLUTIONS SO WON`T GET TOO
EXCITED YET.
&&
.AVIATION...WINDS MAIN CONCERN IN THE DENVER AREA TODAY. BJC NEAR
THE FOOTHILLS ALREADY SEEING PERIODIC WEST WINDS OF 20-25KTS.
WINDS EVEN STRONGER THAN THIS LIKELY TO BECOME MORE PERSIST AT
BJC AS THE MORNING PROGRESSES WITH WLY GUSTS APCHG 45KTS BY
AFTERNOON. SLY WINDS AT DIA AND APA ALSO EXPECTED TO PICK UP IN
THE NEXT FEW HRS AS THEY SHIFT TO A WESTERLY COMPONENT. COULD SEE
GUSTS IN THE 20-35KTS AT BOTH AIRPORTS BY MID TO LATE
AFTERNOON...AND THROUGHOUT THE AFTERNOON. NO PRECIP AT THIS
TIME...SO VFR CIGS AND VSBYS. BY NIGHTFALL SHOULD SEE A STEADY
DROP OF IN WINDS AT DIA AND APA...BUT GUSTY WLY WINDS LIKELY TO
CONTINUE AT BJC FOR MUCH OF THE EVENING.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 5 AM MST TUESDAY FOR COZ031.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR COZ033.
&&
$$
SHORT TERM...BAKER
LONG TERM....ENTREKIN
AVIATION...BAKER
AREA FORECAST DISCUSSION
NWS TAUNTON MA
952 AM EST MON DEC 17 2012
.SYNOPSIS...
A WINTRY MIX OF PRECIPITATION WILL CONTINUE TODAY TO THE NORTH OF MA
TURNPIKE AND AWAY FROM THE IMMEDIATE COAST...RESULTING IN HAZARDOUS
TRAVEL. THE PRECIPITATION SHOULD FINALLY CHANGE TO ALL RAIN TONIGHT
AND TUESDAY...WITH THE NEXT WAVE OF LOW PRESSURE. ANOTHER
POTENTIALLY STRONG LOW PRESSURE SYSTEM SHOULD BRING ANOTHER ROUND OF
MAINLY RAIN AND GUSTY WINDS LATE THU INTO FRI.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
10 AM UPDATE...
ALLOWED FREEZING RAIN TO EXPIRE FOR N CT AND ADJACENT W MA AS
TEMPERATURES HAVE CLIMBED TO ABOVE FREEZING. WINTER WEATHER
ADVISORY REMAINS IN EFFECT FOR MUCH OF INTERIOR MA AND SW NH WHERE
READINGS WILL BE SLOW TO RISE THROUGH AFTERNOON. 12Z HRRR HAS A
GOOD HANDLE ON SURFACE TEMPERATURES AND BRINGS MUCH OF NE MA ABOVE
32F BY NOON...WHILE COLD AIR REMAINS LOCKED FARTHER INLAND DUE TO
WEAK FLOW.
OTHERWISE EXPECT LITTLE CHANGE THROUGH AFTERNOON WITH PERIODS OF
RAIN/DRIZZLE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
***A ROUND OF HEAVY RAIN EXPECTED LATE TONIGHT INTO TUESDAY***
TONIGHT AND TUESDAY...
WE STILL MAY BE DEALING WITH ISOLATED POCKETS OF LIGHT FREEZING RAIN
DURING THE EARLY EVENING ACROSS THE HIGHER TERRAIN OF THE MONADNOCKS
IN SOUTHERN NH. THIS IS BASED ON THE SHALLOW COLD AIR WHICH IS
BEING DEPICTED MUCH BETTER BY SOME OF OUR HIGH RESOLUTION MODELS
HOWEVER...THE NEXT LOW PRESSURE SYSTEM APPROACHING FROM THE WEST
SHOULD ALLOW THESE TEMPS TO RISE OVERNIGHT BRINGING AN END TO ANY
ICING THREATS.
THIS NEXT WAVE OF LOW PRESSURE APPROACHES LATE TONIGHT AND INTO
TUESDAY. THIS SHOULD BRING A PERIOD OF HEAVY RAIN...THAT MAY RESULT
IN TYPICAL NUISANCE URBAN AND POOR DRAINAGE STREET FLOODING. THERE
ALSO IS SOME ELEVATED INSTABILITY...SO DID INCLUDED A SLIGHT CHANCE
OF THUNDER IN THE FORECAST.
THE HEAVIEST/STEADIEST OF THE RAIN SHOULD COME TO AN END BY MID TO
LATE AFTERNOON ON TUE...BUT SOME SCATTERED SHOWERS WILL PERSIST. IN
ADDITION...AREAS OF FOG WILL BE AN ISSUE TONIGHT/TUE AND SOME OF IT
MAY BE LOCALLY DENSE AT TIMES. HIGH TEMPS SHOULD RECOVER WELL INTO
THE 50S ACROSS SOUTHEAST NEW ENGLAND BY TUESDAY AFTERNOON...AS THIS
AREA LOOKS TO WARM SECTOR.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
HIGHLIGHTS...
* A FEW LEFT OVER RAIN/SNOW SHOWERS POSSIBLE TUE NIGHT/WED
* MAINLY RAIN EXPECTED LATE THU/FRI BUT POSSIBLY BEGINS AS SOME
ICE/SNOW ACROSS THE INTERIOR
* A PERIOD OF STRONG WINDS POSSIBLE ON FRIDAY
* COLDER WEATHER LIKELY BY NEXT WEEKEND
DETAILS...
TUESDAY NIGHT AND WEDNESDAY...
VERTICALLY STACKED LOW PRESSURE WILL SLOWLY MOVE AWAY FROM THE
REGION. WHILE MUCH OF TUE NIGHT/WED SHOULD END UP DRY...A FEW LEFT
OVER RAIN AND PERHAPS EVEN A FEW SNOW SHOWERS WILL BE POSSIBLE
ACROSS THE INTERIOR. HOWEVER...PRECIPITATION AMOUNTS SHOULD BE
RATHER LIGHT.
LATE THURSDAY AND FRIDAY...
A POTENTIALLY STRONG LOW PRESSURE SYSTEM WILL BRING MAINLY RAIN TO
THE REGION LATE THU/FRI AS ONE MAIN LOW HEADS UP TOWARDS THE GREAT
LAKES...FLOODING OUR REGION WITH MILD AIR. HOWEVER...IT MAY BE COLD
ENOUGH AT THE ONSET FOR A PERIOD OF ICE/SNOW ACROSS PORTIONS OF
THE INTERIOR. A SECONDARY LOW MAY TRY TO DEVELOP SOMEWHERE NEAR
THE MID ATLANTIC/NORTHEAST COAST. IF THAT ENDS UP TRACKING TO OUR
WEST AS WELL...A STRONG SOUTHERLY LOW LEVEL JET MAY RESULT IN A
PERIOD OF STRONG WINDS MIXING DOWN TO THE SURFACE. ALWAYS A
CHALLENGE TO SEE HOW MUCH OF THESE WINDS WOULD BE ABLE TO MIX DOWN
IN THE INVERSION...BUT SOMETHING TO CERTAINLY WATCH.
SATURDAY AND SUNDAY...
MODELS IN GENERALLY AGREEMENT IN AN UPPER LEVEL TROUGH SETTING UP
ACROSS NEW ENGLAND. THIS SHOULD BRING COLDER WEATHER TO THE REGION.
FOR NOW WE JUST WENT WITH SLIGHT CHANCE POPS...AS UPPER TROUGH
OVERHEAD MAY RESULT IN A FEW FLURRIES/SNOW SHOWERS AT TIMES. THE
ONE THING WILL HAVE TO WATCH IS THE POTENTIAL FOR AN INVERTED TROUGH
TO SETUP. THE 00Z ECMWF HINTS AT THAT FEATURE...WHICH IF HAPPENED
COULD RESULT IN MORE IN THE WAY OF PRECIPITATION. THOSE FEATURES
ARE ALWAYS TRICKY TO FORECAST EVEN IN THE VERY NEAR TERM...SO NO
POINT TALKING MORE ABOUT IT AT THIS POINT BUT ITS SOMETHING TO KEEP
AN EYE ON.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
15Z UPDATE...
MODERATE CONFIDENCE. LITTLE CHANGE IN CONDITIONS THROUGH EARLY
AFTERNOON WITH IFR/MVFR. LIGHT ICING REMAINS A CONCERN ACROSS
INTERIOR MA THROUGH MID AFTERNOON AND ACROSS SW NH INTO THIS
EVENING...GENERALLY 1/10 INCH. PERIODS OF RAIN/DRIZZLE
ELSEWHERE THROUGH TONIGHT.
KBOS TAF...MODERATE CONFIDENCE IN TAF. CIGS MAY BRIEFLY IMPROVE TO
MVFR /OVC012/ FOR A TIME THIS AFTERNOON.
KBDL TAF...MODERATE CONFIDENCE IN TAF. CIGS WILL VARY BETWEEN IFR
/OVC008/ AND MVFR /OVC015/ THROUGH AFTERNOON.
OUTLOOK...TONIGHT THROUGH FRIDAY...
TONIGHT NIGHT AND TUESDAY...MODERATE TO HIGH CONFIDENCE. IFR TO
LIFR CONDITIONS EXPECTED IN RAIN AND AREAS OF FOG. LOW RISK OF AN
ISOLATED THUNDERSTORM OR TWO LATE
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...MODERATE CONFIDENCE. SHOULD
SEE GRADUAL IMPROVEMENT TO VFR CONDITIONS BUT UNCERTAIN ON THE EXACT
TIMING. GUSTY NORTHWEST WINDS EXPECTED ON WED.
THURSDAY AND FRIDAY...MODERATE CONFIDENCE. MVFR TO IFR CONDITIONS
POSSIBLE LATE THU INTO FRIDAY AS THE NEXT SYSTEM MOVES INTO THE
REGION.
&&
.MARINE...
HIGH CONFIDENCE FOR SMALL CRAFT ADVISORY CONDITIONS OUTSIDE BOSTON
HARBOR AND NARRAGANSETT BAY. HAVE EXTEND SCA FOR THE BAYS AS 5FT
WAVES WILL BE SLOW TO REDUCE AS STRONG WIND SPEEDS WILL PREVAIL.
VSBYS WILL REMAIN LOW THROUGH MOST OF THE PERIOD ESP IN HEAVIER
RAIN SHOWERS.
OUTLOOK...TONIGHT THROUGH FRIDAY...
TONIGHT AND TUESDAY...MODERATE TO HIGH CONFIDENCE. SEAS WILL REMAIN
ABOVE SCA THRESHOLDS ACROSS THE OUTER-WATERS...BUT WINDS SHOULD
TEMPORARILY DIMINISH.
TUESDAY NIGHT AND WEDNESDAY...MODERATE TO HIGH CONFIDENCE. IN THE
WAKE OF LOW PRESSURE EXPECT WINDS TO INCREASE OUT OF THE NORTHWEST.
WILL PROBABLY NEED A GALE WATCH VERY LATE TUE NIGHT INTO WED...AS
THERE IS THE POTENTIAL FOR 35 TO 40 KNOT WIND GUSTS OVER THE OPEN
WATERS. ITS CLOSE TO A 5TH PERIOD EVENT SO DECIDED TO LET THE NEXT
SHIFT DECIDE ON THESE POSSIBLE HEADLINES.
THURSDAY AND FRIDAY...MODERATE CONFIDENCE. WINDS/SEAS WILL DIMINISH
TEMPORARILY. HOWEVER...THE NEXT LOW PRESSURE SYSTEM WILL BRING THE
POTENTIAL FOR A PERIOD OF GALE FORCE WIND GUSTS AND HIGH SEAS.
&&
.TIDES/COASTAL FLOODING...
EASTERLY WINDS ALONG WITH THE POTENTIAL FOR A 1 FOOT STORM SURGE MAY
RESULT IN SOME SPLASH OVER DURING TODAY/S MID DAY HIGH TIDE ALONG
THE EASTERN MA COAST. THEREFORE...WE WILL GO AHEAD AND ISSUE A
COASTAL FLOOD STATEMENT FOR THIS REGION.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
MAZ002>010-012-026.
NH...WINTER WEATHER ADVISORY UNTIL 8 PM EST THIS EVENING FOR NHZ011-
012-015.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
ANZ231>234.
SMALL CRAFT ADVISORY UNTIL 5 PM EST TUESDAY FOR ANZ235-237-250-
251-254>256.
&&
$$
SYNOPSIS...FRANK/DUNTEN
NEAR TERM...JWD
SHORT TERM...FRANK
LONG TERM...FRANK
AVIATION...JWD
MARINE...BELK/FRANK/DUNTEN
TIDES/COASTAL FLOODING...DUNTEN
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
328 PM EST MON DEC 17 2012
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE THROUGH THE FORECAST AREA
TONIGHT. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL OCCUR
AHEAD OF THE FRONT. DRY HIGH PRESSURE BEHIND THE FRONT WILL
DOMINATE TUESDAY AND WEDNESDAY. ANOTHER COLD FRONT WILL MOVE INTO
THE AREA THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
SHOWERS HAVE OVERSPREAD THE FORECAST AREA ASSOCIATED WITH THE H85
JET. SURFACE-BASED INSTABILITY WAS CONFINED TO SOUTH GEORGIA
WHERE EARLY AFTERNOON LI VALUES WERE NEAR -2. THE NAM FORECAST OF
LI/S LOWERING TO NEAR -4 IN THE FORECAST AREA DURING THE AFTERNOON
APPEARS OVERDONE. INSTABILITY SHOULD REMAIN LIMITED BECAUSE OF
CLOUDINESS AND WIDESPREAD RAIN. THE RAP APPEARS MORE REASONABLE
WITH POSITIVE LI/S THROUGH THE AFTERNOON WITH GREATER INSTABILITY
THIS EVENING AFTER THE MOISTURE BECOMES SHALLOW AND MORE COOLING
ALOFT OCCURS AS THE UPPER TROUGH MOVES INTO THE AREA. SEVERE
THUNDERSTORMS ARE NOT OUT OF THE QUESTION BECAUSE OF HIGH SHEAR
BUT WE BELIEVE THE CHANCE IS LOW BECAUSE OF A LACK OF SURFACE-
BASED INSTABILITY. SHOWERS SHOULD END FROM WEST TO EAST AS THE
DEEPER MOISTURE AND H85 JET AHEAD OF THE FRONT SHIFTS EAST OF THE
AREA THIS EVENING. MIXING ASSOCIATED WITH THE FRONT SHOULD HELP HOLD UP
TEMPERATURES TONIGHT. WE USED THE WARMER TEMPERATURE GUIDANCE.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
DRY HIGH PRESSURE BEHIND THE COLD FRONT WILL DOMINATE TUESDAY
THROUGH WEDNESDAY NIGHT. STRONG RADIATIONAL COOLING WILL OCCUR
TUESDAY NIGHT. THE TEMPERATURE GUIDANCE WAS CLOSE THROUGH THE
PERIOD.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
THE GFS AND ECMWF SHOW A COLD FRONT IN THE FORECAST AREA THURSDAY
OR THURSDAY NIGHT. THE MODELS SHOW STRONG SHEAR ASSOCIATED WITH
THIS FRONT WITH H85 WINDS NEAR 60 KNOTS. THUNDERSTORMS WITH
DAMAGING WIND COULD POSSIBLY OCCUR ALTHOUGH INSTABILITY SHOULD BE
A LIMITING FACTOR. DRY HIGH PRESSURE BEHIND THIS FRONT SHOULD
DOMINATE DURING THE REST OF THE MEDIUM-RANGE PERIOD.
&&
.AVIATION /21Z MONDAY THROUGH SATURDAY/...
HIGHLY VARIABLE CONDITIONS CONTINUE ACROSS THE TAF SITES...WITH MVFR
AND IFR EXPECTED TO DOMINATE THE PERIOD.
COLD FRONT MAKING SLOW PROGRESS ACROSS THE WESTERN GULF REGION. AN
AREA OF SHOWER ALONG WITH SOME THUNDERSTORMS ACROSS EXTREME SRN GA
AND THE PANHANDLE OF FL WILL CONTINUE TO MOVE NORTHEAST THROUGHOUT
THE AFTERNOON. SATELLITE IMAGERY SHOWS PLENTY OF CLOUDS ACROSS THE
AREA AND PLENTY MORE UPSTREAM...SO EXPECT CLOUDY CONDITIONS FOR MUCH
OF THE TAF PERIOD. HAVE CONTINUED WITH RAIN IN THE FORECAST THROUGH
THE AFTERNOON...HOWEVER HAVE NOT INCLUDED THUNDER. EXPECT
THUNDERSTORMS TO REMAIN SOUTH AND EAST OF THE TERMINALS WHERE
AIR MASS IS UNSTABLE. THE RAIN WILL BEGIN TO DIMINISH ACROSS THE
AREA THIS EVENING INTO TONIGHT...HOWEVER WITH PLENTY OF MOISTURE
AND 30 TO 40 KT LOW LEVEL JET EXPECT LOW CLOUDS AND FOG TO LINGER
LATE INTO THE PERIOD. ON TUESDAY...EXPECT CLEARING TO BEGIN RATHER
QUICKLY AS TIGHT SURFACE PRESSURE GRADIENT BETWEEN DEPARTING FRONT
AND HIGH BUILDING IN FROM THE WEST WILL PRODUCE BREEZY CONDITIONS
BEGINNING AROUND 15Z.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS AGAIN POSSIBLE THURSDAY
MORNING INTO FRIDAY MORNING AS ANOTHER COLD FRONT CROSSES THE
REGION. BREEZY CONDITIONS POSSIBLE THURSDAY NIGHT AND FRIDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
214 PM EST MON DEC 17 2012
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE THROUGH THE FORECAST AREA
TONIGHT. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL OCCUR
AHEAD OF THE FRONT. DRY HIGH PRESSURE BEHIND THE FRONT WILL
DOMINATE TUESDAY AND WEDNESDAY. ANOTHER COLD FRONT WILL MOVE INTO
THE AREA THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SHOWERS HAVE OVERSPREAD THE FORECAST AREA ASSOCIATED WITH THE H85
JET. SURFACE-BASED INSTABILITY WAS CONFINED TO SOUTH GEORGIA
WHERE EARLY AFTERNOON LI VALUES WERE NEAR -2. THE NAM FORECAST OF
LI/S LOWERING TO NEAR -4 IN THE FORECAST AREA DURING THE AFTERNOON
APPEARS OVERDONE. INSTABILITY SHOULD REMAIN LIMITED BECAUSE OF
CLOUDINESS AND WIDESPREAD RAIN. THE RAP APPEARS MORE REASONABLE
WITH POSITIVE LI/S THROUGH THE AFTERNOON WITH GREATER INSTABILITY
THIS EVENING AFTER THE MOISTURE BECOMES SHALLOW AND MORE COOLING
ALOFT OCCURS AS THE UPPER TROUGH MOVES INTO THE AREA. SEVERE
THUNDERSTORMS ARE NOT OUT OF THE QUESTION BECAUSE OF HIGH SHEAR
BUT WE BELIEVE THE CHANCE IS LOW BECAUSE OF A LACK OF SURFACE-
BASED INSTABILITY. SHOWERS SHOULD END FROM WEST TO EAST AS THE
DEEPER MOISTURE AND H85 JET AHEAD OF THE FRONT SHIFTS EAST OF THE
AREA THIS EVENING. MIXING ASSOCIATED WITH THE FRONT SHOULD HELP HOLD UP
TEMPERATURES TONIGHT. WE USED THE WARMER TEMPERATURE GUIDANCE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
DRY HIGH PRESSURE BEHIND THE COLD FRONT WILL DOMINATE TUESDAY
THROUGH WEDNESDAY NIGHT. STRONG RADIATIONAL COOLING WILL OCCUR
TUESDAY NIGHT. THE TEMPERATURE GUIDANCE WAS CLOSE THROUGH THE
PERIOD.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE GFS AND ECMWF SHOW A COLD FRONT IN THE FORECAST AREA THURSDAY
OR THURSDAY NIGHT. THE MODELS SHOW STRONG SHEAR ASSOCIATED WITH
THIS FRONT WITH H85 WINDS NEAR 60 KNOTS. THUNDERSTORMS WITH
DAMAGING WIND COULD POSSIBLY OCCUR ALTHOUGH INSTABILITY SHOULD BE
A LIMITING FACTOR. DRY HIGH PRESSURE BEHIND THIS FRONT SHOULD
DOMINATE DURING THE REST OF THE MEDIUM-RANGE PERIOD.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
HIGHLY VARIABLE CONDITIONS CONTINUE ACROSS THE TAF SITES...WITH MVFR
AND IFR EXPECTED TO DOMINATE THE PERIOD.
COLD FRONT MAKING SLOW PROGRESS ACROSS THE WESTERN GULF REGION. AN
AREA OF SHOWER ALONG WITH SOME THUNDERSTORMS ACROSS EXTREME SRN GA
AND THE PANHANDLE OF FL WILL CONTINUE TO MOVE NORTHEAST THROUGHOUT
THE AFTERNOON. SATELLITE IMAGERY SHOWS PLENTY OF CLOUDS ACROSS THE
AREA AND PLENTY MORE UPSTREAM...SO EXPECT CLOUDY CONDITIONS FOR MUCH
OF THE TAF PERIOD. HAVE CONTINUED WITH RAIN IN THE FORECAST THROUGH
THE AFTERNOON...HOWEVER HAVE NOT INCLUDED THUNDER AS CONFIDENCE IS
LOW AT THIS TIME FOR OCCURRENCE AT ANY TAF SITES. THE BEST CHANCE
FOR THUNDER WOULD BE THE SOUTHERN/EASTERN TAFS CLOSER TO THE MORE
UNSTABLE CONDITIONS...AGS/DNL/OGB. THE RAIN WILL BEGIN TO DIMINISH
ACROSS THE AREA THIS EVENING INTO TONIGHT...HOWEVER WITH PLENTY OF
MOISTURE AND 30 TO 40 KT LOW LEVEL JET EXPECT LOW CLOUDS AND FOG TO
LINGER LATE INTO THE PERIOD. ON TUESDAY...EXPECT CLEARING TO BEGIN
RATHER QUICKLY AS TIGHT SURFACE PRESSURE GRADIENT BETWEEN DEPARTING
FRONT AND HIGH BUILDING IN FROM THE WEST WILL PRODUCE BREEZY
CONDITIONS BEGINNING AROUND 15Z.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS AGAIN POSSIBLE THURSDAY
MORNING INTO FRIDAY MORNING AS ANOTHER COLD FRONT CROSSES THE
REGION. BREEZY CONDITIONS POSSIBLE THURSDAY NIGHT AND FRIDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
119 PM EST MON DEC 17 2012
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE THROUGH THE FORECAST AREA
TONIGHT. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL OCCUR
AHEAD OF THE FRONT. DRY HIGH PRESSURE BEHIND THE FRONT WILL
DOMINATE TUESDAY AND WEDNESDAY. ANOTHER COLD FRONT WILL MOVE INTO
THE AREA THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SHOWERS HAVE OVERSPREAD THE FORECAST AREA ASSOCIATED WITH THE H85
JET. SURFACE-BASED INSTABILITY WAS CONFINED TO SOUTH GEORGIA
WHERE EARLY AFTERNOON LI VALUES WERE NEAR -2. THE NAM FORECAST OF
LI/S LOWERING TO NEAR -4 IN THE FORECAST AREA DURING THE AFTERNOON
APPEARS OVERDONE. INSTABILITY SHOULD REMAIN LIMITED BECAUSE OF
CLOUDINESS AND WIDESPREAD RAIN. THE RAP APPEARS MORE REASONABLE
WITH POSITIVE LI/S THROUGH THE AFTERNOON WITH GREATER INSTABILITY
THIS EVENING AFTER THE MOISTURE BECOMES SHALLOW AND MORE COOLING
ALOFT OCCURS AS THE UPPER TROUGH MOVES INTO THE AREA. SEVERE
THUNDERSTORMS ARE NOT OUT OF THE QUESTION BECAUSE OF HIGH SHEAR
BUT WE BELIEVE THE CHANCE IS LOW BECAUSE OF A LACK OF SURFACE-
BASED INSTABILITY. SHOWERS SHOULD END FROM WEST TO EAST AS THE
DEEPER MOISTURE AND H85 JET AHEAD OF THE FRONT SHIFTS EAST OF THE
AREA THIS EVENING. MIXING ASSOCIATED WITH THE FRONT SHOULD HELP HOLD UP
TEMPERATURES TONIGHT. WE USED THE WARMER TEMPERATURE GUIDANCE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
DRY HIGH PRESSURE BEHIND THE COLD FRONT WILL DOMINATE TUESDAY
THROUGH WEDNESDAY NIGHT. STRONG RADIATIONAL COOLING WILL OCCUR
TUESDAY NIGHT. THE TEMPERATURE GUIDANCE WAS CLOSE THROUGH THE
PERIOD.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE GFS AND ECMWF SHOW A COLD FRONT IN THE FORECAST AREA THURSDAY
OR THURSDAY NIGHT. THE MODELS SHOW STRONG SHEAR ASSOCIATED WITH
THIS FRONT WITH H85 WINDS NEAR 60 KNOTS. THUNDERSTORMS WITH
DAMAGING WIND COULD POSSIBLY OCCUR ALTHOUGH INSTABILITY SHOULD BE
A LIMITING FACTOR. DRY HIGH PRESSURE BEHIND THIS FRONT SHOULD
DOMINATE DURING THE REST OF THE MEDIUM-RANGE PERIOD.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
HIGHLY VARIABLE CONDITIONS CONTINUE ACROSS THE TAF SITES...WITH MVFR
AND IFR EXPECTED TO DOMINATE THE PERIOD.
COLD FRONT MAKING SLOW PROGRESS ACROSS THE WESTERN GULF REGION. AN
AREA OF SHOWER ALONG WITH SOME THUNDERSTORMS ACROSS EXTREME SRN GA
AND THE PANHANDLE OF FL WILL CONTINUE TO MOVE NORTHEAST THROUGHOUT
THE AFTERNOON. SATELLITE IMAGERY SHOWS PLENTY OF CLOUDS ACROSS THE
AREA AND PLENTY MORE UPSTREAM...SO EXPECT CLOUDY CONDITIONS FOR MUCH
OF THE TAF PERIOD. HAVE CONTINUED WITH RAIN IN THE FORECAST THROUGH
THE AFTERNOON...HOWEVER HAVE NOT INCLUDED THUNDER AS CONFIDENCE IS
LOW AT THIS TIME FOR OCCURRENCE AT ANY TAF SITES. THE BEST CHANCE
FOR THUNDER WOULD BE THE SOUTHERN/EASTERN TAFS CLOSER TO THE MORE
UNSTABLE CONDITIONS...AGS/DNL/OGB. THE RAIN WILL BEGIN TO DIMINISH
ACROSS THE AREA THIS EVENING INTO TONIGHT...HOWEVER WITH PLENTY OF
MOISTURE AND 30 TO 40 KT LOW LEVEL JET EXPECT LOW CLOUDS AND FOG TO
LINGER LATE INTO THE PERIOD. ON TUESDAY...EXPECT CLEARING TO BEGIN
RATHER QUICKLY AS TIGHT SURFACE PRESSURE GRADIENT BETWEEN DEPARTING
FRONT AND HIGH BUILDING IN FROM THE WEST WILL PRODUCE BREEZY
CONDITIONS BEGINNING AROUND 15Z.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS AGAIN POSSIBLE THURSDAY
MORNING INTO FRIDAY MORNING AS ANOTHER COLD FRONT CROSSES THE
REGION. BREEZY CONDITIONS POSSIBLE THURSDAY NIGHT AND FRIDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
109 PM EST MON DEC 17 2012
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE THROUGH THE FORECAST AREA
TONIGHT. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL OCCUR
AHEAD OF THE FRONT. DRY HIGH PRESSURE BEHIND THE FRONT WILL
DOMINATE TUESDAY AND WEDNESDAY. ANOTHER COLD FRONT WILL MOVE INTO
THE AREA THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SHOWERS HAVE OVERSPREAD THE FORECAST AREA ASSOCIATED WITH THE H85
JET. SURFACE-BASED INSTABILITY WAS CONFINED TO SOUTH GEORGIA
WHERE EARLY AFTERNOON LI VALUES WERE NEAR -2. THE NAM FORECAST OF
LI/S LOWERING TO NEAR -4 IN THE FORECAST AREA DURING THE AFTERNOON
APPEARS OVERDONE. INSTABILITY SHOULD REMAIN LIMITED BECAUSE OF
CLOUDINESS AND WIDESPREAD RAIN. THE RAP APPEARS MORE REASONABLE
WITH POSITIVE LI/S THROUGH THE AFTERNOON WITH GREATER INSTABILITY
THIS EVENING AFTER THE MOISTURE BECOMES SHALLOW AND MORE COOLING
ALOFT OCCURS AS THE UPPER TROUGH MOVES INTO THE AREA. SEVERE
THUNDERSTORMS ARE NOT OUT OF THE QUESTION BECAUSE OF HIGH SHEAR
BUT WE BELIEVE THE CHANCE IS LOW BECAUSE OF A LACK OF SURFACE-
BASED INSTABILITY. SHOWERS SHOULD END FROM WEST TO EAST AS THE
DEEPER MOISTURE AND H85 JET AHEAD OF THE FRONT SHIFTS EAST OF THE
AREA. MIXING ASSOCIATED WITH THE FRONT SHOULD HELP HOLD UP
TEMPERATURES TONIGHT. WE USED THE WARMER TEMPERATURE GUIDANCE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
DRY HIGH PRESSURE BEHIND THE COLD FRONT WILL DOMINATE TUESDAY
THROUGH WEDNESDAY NIGHT. STRONG RADIATIONAL COOLING WILL OCCUR
TUESDAY NIGHT. THE TEMPERATURE GUIDANCE WAS CLOSE THROUGH THE
PERIOD.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE GFS AND ECMWF SHOW A COLD FRONT IN THE FORECAST AREA THURSDAY
OR THURSDAY NIGHT. THE MODELS SHOW STRONG SHEAR ASSOCIATED WITH
THIS FRONT WITH H85 WINDS NEAR 60 KNOTS. THUNDERSTORMS WITH
DAMAGING WIND COULD POSSIBLY OCCUR ALTHOUGH INSTABILITY SHOULD BE
A LIMITING FACTOR. DRY HIGH PRESSURE BEHIND THIS FRONT SHOULD
DOMINATE DURING THE REST OF THE MEDIUM-RANGE PERIOD.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
HIGHLY VARIABLE CONDITIONS CONTINUE ACROSS THE TAF SITES...WITH MVFR
AND IFR EXPECTED TO DOMINATE THE PERIOD.
COLD FRONT MAKING SLOW PROGRESS ACROSS THE WESTERN GULF REGION. AN
AREA OF SHOWER ALONG WITH SOME THUNDERSTORMS ACROSS EXTREME SRN GA
AND THE PANHANDLE OF FL WILL CONTINUE TO MOVE NORTHEAST THROUGHOUT
THE AFTERNOON. SATELLITE IMAGERY SHOWS PLENTY OF CLOUDS ACROSS THE
AREA AND PLENTY MORE UPSTREAM...SO EXPECT CLOUDY CONDITIONS FOR MUCH
OF THE TAF PERIOD. HAVE CONTINUED WITH RAIN IN THE FORECAST THROUGH
THE AFTERNOON...HOWEVER HAVE NOT INCLUDED THUNDER AS CONFIDENCE IS
LOW AT THIS TIME FOR OCCURRENCE AT ANY TAF SITES. THE BEST CHANCE
FOR THUNDER WOULD BE THE SOUTHERN/EASTERN TAFS CLOSER TO THE MORE
UNSTABLE CONDITIONS...AGS/DNL/OGB. THE RAIN WILL BEGIN TO DIMINISH
ACROSS THE AREA THIS EVENING INTO TONIGHT...HOWEVER WITH PLENTY OF
MOISTURE AND 30 TO 40 KT LOW LEVEL JET EXPECT LOW CLOUDS AND FOG TO
LINGER LATE INTO THE PERIOD. ON TUESDAY...EXPECT CLEARING TO BEGIN
RATHER QUICKLY AS TIGHT SURFACE PRESSURE GRADIENT BETWEEN DEPARTING
FRONT AND HIGH BUILDING IN FROM THE WEST WILL PRODUCE BREEZY
CONDITIONS BEGINNING AROUND 15Z.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS AGAIN POSSIBLE THURSDAY
MORNING INTO FRIDAY MORNING AS ANOTHER COLD FRONT CROSSES THE
REGION. BREEZY CONDITIONS POSSIBLE THURSDAY NIGHT AND FRIDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1231 PM EST MON DEC 17 2012
.PREV DISCUSSION... /ISSUED 654 AM EST MON DEC 17 2012/
SHORT TERM /TODAY THROUGH TUESDAY/...
MAIN FCST CONCERN REMAINS CHC FOR SVR CONVECTION TODAY. 00Z MODEL
RUNS NOT SHOWING MUCH CHANGE FROM PREVIOUS RUNS...BEST TIMING FOR
VERTICAL WIND SHEAR AND INSTABILITY WILL BE 15Z-21Z. PROBLEM IS
THAT WE SAW NORTH WINDS MUCH OF THE DAY AND EVENING SUNDAY...IN
RESPONSE TO LOW FROM LARGE PERSISTENT PRECIP AREA...WHICH
MINIMIZED NORTHWARD MOISTURE TRANSPORT. LATEST RAP ANALYSIS ALSO
SHOWING THAT MUCAPE REMAINS NEAR ZERO IN THE REGION EXCEPT ALONG
THE GULF COAST. USUALLY SEE ELEVATED INSTABILITY SURGING NORTHEAST
AT THIS TIME OF NIGHT PRECEDING FRONT AND STORMS. 06Z NAM STARTING
TO AGREE WITH LATEST ANALYSIS IN THE NEAR TERM BUT STILL APPEARS A
LITTLE TOO QUICK BRINGING HIGHER THETA-E AIR AND HIGHER CAPE NORTH
BY 15Z. ASSUMING MODELS ON TRACK WITH INSTABILITY...SHOULD SEE SVR
THREAT DEVELOP AFTER 15Z. DO NOT SEE ANY THREAT OF HAIL GREATER
THAN ONE INCH. DAMAGING WINDS AND AN ISOLATED TORNADO THREAT
REMAIN POSSIBLE BUT CONTINGENT ON MOISTURE TRANSPORT AND
INSTABILITY DEVELOPING AS FCST. WILL HAVE TO WATCH REAL TIME
ANALYSIS CLOSELY THIS MORNING.
PRECIP WILL MOVE OUT QUICKLY TONIGHT. NO ISSUES WITH FCST BEYOND
THIS. DRY AIR SHOULD FILTER IN SLOWLY BUT ENOUGH TO PRECLUDE
DEVELOPMENT OF FOG. USED MAV/MET/ECMWF MOS BLEND FOR TEMPS.
SNELSON
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MAIN FORECAST CONCERN IN THE EXTENDED PERIODS IS THE FAIRLY STRONG
COLD FRONT EXPECTED ON THURSDAY. WEAK RIDGING OVER THE SOUTHEAST
AT THE BEGINNING OF THE EXTENDED PERIODS...WITH NEARLY NEARLY
ZONAL UPPER LEVEL FLOW...SFC HIGH AND DRY CONDITIONS ON WEDNESDAY.
ALTHOUGH THERE ARE SOME DISCREPANCIES EXTENDED MODELS ARE IN GOOD
AGREEMENT WITH GENERAL PATTERN MIDWEEK. AN UPPER LEVEL SHORT WAVE
CROSSES THE ROCKIES ON WEDNESDAY LIFTING INTO THE OHIO VALLEY BY
THURSDAY AFTERNOON. GFS IS DEEPER AND CUTS OFF THE LOW BY THURSDAY
AFTERNOON...ECMWF IS SLOWER TO CUT OFF LOW BUT BY THURSDAY NIGHT
BOTH MODELS ARE SIMILAR IN LOCATION AND STRENGTH OF LOW. WITH WEAK
RIDGING AND SURFACE HIGH SHIFTING EAST ON WEDNESDAY MODELS ARE IN
AGREEMENT THAT BEST MOISTURE RETURNS THURSDAY MORNING AHEAD OF THE
COLD FRONT WHICH MOVES ACROSS THE FORECAST AREA RATHER QUICKLY BY
THURSDAY EVENING. INSTABILITY IS LIMITED HOWEVER BOTH GFS AND
ECMWF AREA SHOWING GOOD SHEAR...AND GIVEN THE STRENGTH OF THE FRONT
WILL CONTINUE ISOLATED THUNDERSTORMS DURING THE DAY. RAINFALL
RATES WILL BE HALF INCH OR LESS BASED UPON THE SPEED OF THE STORM.
ZONAL FLOW ALOFT AND SURFACE HIGH PRESSURE BUILD BACK IN FOR THE
WEEKEND. GFS SHOWING SOME MOISTURE RETURN SATURDAY BUT MAINLY
EXPECT AN INCREASE IN CLOUDS ACROSS THE FORECAST AREA SATURDAY AND
SUNDAY. GUIDANCE TEMPERATURES ARE PRETTY CLOSE AND WILL TAKE A
BLEND OF MAV/ECMWF MOS THROUGH THE EXTENDED PERIODS.
ATWELL
&&
.AVIATION...
18Z UPDATE...
IFR CEILINGS THE MAIN CONCERN FOR MOST TAF SITES EVENTUALLY
DEVELOPING OVER MCN. MAIN VSBY RESTRICTIONS ASSOCIATED WITH THE
RAIN AREA WITH BEST THUNDERSTORMS CHANCES ABOUT MCN S THIS AFTERNOON.
PRECIP DIMINISHES THIS AFTERNOON AND EVENING. UNSURE HOW MUCH FOG
THERE COULD BE OVERNIGHT. SURFACE WINDS SSW BECOMING W 5-10 KTS.
//ATL CONFIDENCE...18Z UPDATE...
HIGH CONFIDENCE FOR IFR CIGS...WEATHER AND WINDS INTO THE OVERNIGHT.
LOW TO MEDIUM CONFIDENCE FOR VSBYS.
BDL
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 58 47 62 36 / 70 20 0 0
ATLANTA 59 47 61 41 / 50 20 0 0
BLAIRSVILLE 54 41 56 29 / 50 40 0 0
CARTERSVILLE 61 42 59 32 / 30 20 0 0
COLUMBUS 63 50 65 40 / 90 10 0 0
GAINESVILLE 57 45 60 39 / 50 20 0 0
MACON 62 49 66 35 / 100 20 0 0
ROME 61 41 60 33 / 40 20 0 0
PEACHTREE CITY 60 42 62 32 / 60 20 0 0
VIDALIA 73 56 69 42 / 90 20 0 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BDL
LONG TERM....DEESE
AVIATION...BDL
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
654 AM EST MON DEC 17 2012
.PREV DISCUSSION... /ISSUED 411 AM EST MON DEC 17 2012/
SHORT TERM /TODAY THROUGH TUESDAY/...
MAIN FCST CONCERN REMAINS CHC FOR SVR CONVECTION TODAY. 00Z MODEL
RUNS NOT SHOWING MUCH CHANGE FROM PREVIOUS RUNS...BEST TIMING FOR
VERTICAL WIND SHEAR AND INSTABILITY WILL BE 15Z-21Z. PROBLEM IS
THAT WE SAW NORTH WINDS MUCH OF THE DAY AND EVENING SUNDAY...IN
RESPONSE TO LOW FROM LARGE PERSISTENT PRECIP AREA...WHICH MINIMIZED
NORTHWARD MOISTURE TRANSPORT. LATEST RAP ANALYSIS ALSO SHOWING THAT
MUCAPE REMAINS NEAR ZERO IN THE REGION EXCEPT ALONG THE GULF COAST.
USUALLY SEE ELEVATED INSTABILITY SURGING NORTHEAST AT THIS TIME OF
NIGHT PRECEDING FRONT AND STORMS. 06Z NAM STARTING TO AGREE WITH
LATEST ANALYSIS IN THE NEAR TERM BUT STILL APPEARS A LITTLE TOO
QUICK BRINGING HIGHER THETA-E AIR AND HIGHER CAPE NORTH BY 15Z.
ASSUMING MODELS ON TRACK WITH INSTABILITY...SHOULD SEE SVR THREAT
DEVELOP AFTER 15Z. DO NOT SEE ANY THREAT OF HAIL GREATER THAN ONE
INCH. DAMAGING WINDS AND AN ISOLATED TORNADO THREAT REMAIN POSSIBLE
BUT CONTINGENT ON MOISTURE TRANSPORT AND INSTABILITY DEVELOPING AS
FCST. WILL HAVE TO WATCH REAL TIME ANALYSIS CLOSELY THIS MORNING.
PRECIP WILL MOVE OUT QUICKLY TONIGHT. NO ISSUES WITH FCST BEYOND
THIS. DRY AIR SHOULD FILTER IN SLOWLY BUT ENOUGH TO PRECLUDE
DEVELOPMENT OF FOG. USED MAV/MET/ECMWF MOS BLEND FOR TEMPS.
SNELSON
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MAIN FORECAST CONCERN IN THE EXTENDED PERIODS IS THE FAIRLY STRONG
COLD FRONT EXPECTED ON THURSDAY. WEAK RIDGING OVER THE SOUTHEAST
AT THE BEGINNING OF THE EXTENDED PERIODS...WITH NEARLY NEARLY
ZONAL UPPER LEVEL FLOW...SFC HIGH AND DRY CONDITIONS ON WEDNESDAY.
ALTHOUGH THERE ARE SOME DISCREPANCIES EXTENDED MODELS ARE IN GOOD
AGREEMENT WITH GENERAL PATTERN MIDWEEK. AN UPPER LEVEL SHORT WAVE
CROSSES THE ROCKIES ON WEDNESDAY LIFTING INTO THE OHIO VALLEY BY
THURSDAY AFTERNOON. GFS IS DEEPER AND CUTS OFF THE LOW BY THURSDAY
AFTERNOON...ECMWF IS SLOWER TO CUT OFF LOW BUT BY THURSDAY NIGHT
BOTH MODELS ARE SIMILAR IN LOCATION AND STRENGTH OF LOW. WITH WEAK
RIDGING AND SURFACE HIGH SHIFTING EAST ON WEDNESDAY MODELS ARE IN
AGREEMENT THAT BEST MOISTURE RETURNS THURSDAY MORNING AHEAD OF THE
COLD FRONT WHICH MOVES ACROSS THE FORECAST AREA RATHER QUICKLY BY
THURSDAY EVENING. INSTABILITY IS LIMITED HOWEVER BOTH GFS AND
ECMWF AREA SHOWING GOOD SHEAR...AND GIVEN THE STRENGTH OF THE FRONT
WILL CONTINUE ISOLATED THUNDERSTORMS DURING THE DAY. RAINFALL
RATES WILL BE HALF INCH OR LESS BASED UPON THE SPEED OF THE STORM.
ZONAL FLOW ALOFT AND SURFACE HIGH PRESSURE BUILD BACK IN FOR THE
WEEKEND. GFS SHOWING SOME MOISTURE RETURN SATURDAY BUT MAINLY
EXPECT AN INCREASE IN CLOUDS ACROSS THE FORECAST AREA SATURDAY AND
SUNDAY. GUIDANCE TEMPERATURES ARE PRETTY CLOSE AND WILL TAKE A
BLEND OF MAV/ECMWF MOS THROUGH THE EXTENDED PERIODS.
ATWELL
&&
.AVIATION...
12Z UPDATE...
LIFR CIGS WERE SLOW TO DEVELOP BUT FINALLY DEVELOPED IN NORTH GA
AIRPORTS INCLUDING ATL. PRECIP MOVING IN THIS MORNING AS WELL BUT
CIGS/VSBYS SLOW TO FALL TO THE WEST WHERE RAIN HAS BEEN FALLING.
WILL CONTINUE TO MONITOR TRENDS BUT EXPECT CIGS TO FALL TO NEAR
IFR ONCE RAIN COOLS AND FURTHER SATURATES LOW LEVELS. INSTABILITY
HAS BEEN SLOW TO DEVELOP OVERNIGHT...NOW EXPECT MOST INSTABILITY
THIS AFTERNOON TO BE OVER MIDDLE GA SO HAVE REMOVED TSRA FROM FCST
FOR ATL METRO TAFS AND AHN. WINDS HAVE ALREADY BECOME SSW AND
SHOULD SWITCH TO WEST AROUND 21Z WHEN PRECIP TAPERS OFF AND FRONT
MOVES IN.
//ATL CONFIDENCE...12Z UPDATE...
MEDIUM CONFIDENCE ON IFR CIGS THIS MORNING.
HIGH ON ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 62 47 62 36 / 90 20 5 5
ATLANTA 64 47 61 41 / 90 10 5 5
BLAIRSVILLE 57 41 56 29 / 90 20 5 5
CARTERSVILLE 63 42 59 32 / 100 10 5 5
COLUMBUS 69 50 65 40 / 90 10 5 5
GAINESVILLE 60 45 60 39 / 90 20 5 5
MACON 70 49 66 35 / 90 20 5 5
ROME 64 41 60 33 / 90 10 5 5
PEACHTREE CITY 66 42 62 32 / 90 10 5 5
VIDALIA 74 56 69 42 / 80 50 0 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....ATWELL
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
411 AM EST MON DEC 17 2012
.SHORT TERM /TODAY THROUGH TUESDAY/...
MAIN FCST CONCERN REMAINS CHC FOR SVR CONVECTION TODAY. 00Z MODEL
RUNS NOT SHOWING MUCH CHANGE FROM PREVIOUS RUNS...BEST TIMING FOR
VERTICAL WIND SHEAR AND INSTABILITY WILL BE 15Z-21Z. PROBLEM IS
THAT WE SAW NORTH WINDS MUCH OF THE DAY AND EVENING SUNDAY...IN
RESPONSE TO LOW FROM LARGE PERSISTENT PRECIP AREA...WHICH MINIMIZED
NORTHWARD MOISTURE TRANSPORT. LATEST RAP ANALYSIS ALSO SHOWING THAT
MUCAPE REMAINS NEAR ZERO IN THE REGION EXCEPT ALONG THE GULF COAST.
USUALLY SEE ELEVATED INSTABILITY SURGING NORTHEAST AT THIS TIME OF
NIGHT PRECEDING FRONT AND STORMS. 06Z NAM STARTING TO AGREE WITH
LATEST ANALYSIS IN THE NEAR TERM BUT STILL APPEARS A LITTLE TOO
QUICK BRINGING HIGHER THETA-E AIR AND HIGHER CAPE NORTH BY 15Z.
ASSUMING MODELS ON TRACK WITH INSTABILITY...SHOULD SEE SVR THREAT
DEVELOP AFTER 15Z. DO NOT SEE ANY THREAT OF HAIL GREATER THAN ONE
INCH. DAMAGING WINDS AND AN ISOLATED TORNADO THREAT REMAIN POSSIBLE
BUT CONTINGENT ON MOISTURE TRANSPORT AND INSTABILITY DEVELOPING AS
FCST. WILL HAVE TO WATCH REAL TIME ANALYSIS CLOSELY THIS MORNING.
PRECIP WILL MOVE OUT QUICKLY TONIGHT. NO ISSUES WITH FCST BEYOND
THIS. DRY AIR SHOULD FILTER IN SLOWLY BUT ENOUGH TO PRECLUDE
DEVELOPMENT OF FOG. USED MAV/MET/ECMWF MOS BLEND FOR TEMPS.
SNELSON
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MAIN FORECAST CONCERN IN THE EXTENDED PERIODS IS THE FAIRLY STRONG
COLD FRONT EXPECTED ON THURSDAY. WEAK RIDGING OVER THE SOUTHEAST
AT THE BEGINNING OF THE EXTENDED PERIODS...WITH NEARLY NEARLY
ZONAL UPPER LEVEL FLOW...SFC HIGH AND DRY CONDITIONS ON WEDNESDAY.
ALTHOUGH THERE ARE SOME DISCREPANCIES EXTENDED MODELS ARE IN GOOD
AGREEMENT WITH GENERAL PATTERN MIDWEEK. AN UPPER LEVEL SHORT WAVE
CROSSES THE ROCKIES ON WEDNESDAY LIFTING INTO THE OHIO VALLEY BY
THURSDAY AFTERNOON. GFS IS DEEPER AND CUTS OFF THE LOW BY THURSDAY
AFTERNOON...ECMWF IS SLOWER TO CUT OFF LOW BUT BY THURSDAY NIGHT
BOTH MODELS ARE SIMILAR IN LOCATION AND STRENGTH OF LOW. WITH WEAK
RIDGING AND SURFACE HIGH SHIFTING EAST ON WEDNESDAY MODELS ARE IN
AGREEMENT THAT BEST MOISTURE RETURNS THURSDAY MORNING AHEAD OF THE
COLD FRONT WHICH MOVES ACROSS THE FORECAST AREA RATHER QUICKLY BY
THURSDAY EVENING. INSTABILITY IS LIMITED HOWEVER BOTH GFS AND
ECMWF AREA SHOWING GOOD SHEAR...AND GIVEN THE STRENGTH OF THE FRONT
WILL CONTINUE ISOLATED THUNDERSTORMS DURING THE DAY. RAINFALL
RATES WILL BE HALF INCH OR LESS BASED UPON THE SPEED OF THE STORM.
ZONAL FLOW ALOFT AND SURFACE HIGH PRESSURE BUILD BACK IN FOR THE
WEEKEND. GFS SHOWING SOME MOISTURE RETURN SATURDAY BUT MAINLY
EXPECT AN INCREASE IN CLOUDS ACROSS THE FORECAST AREA SATURDAY AND
SUNDAY. GUIDANCE TEMPERATURES ARE PRETTY CLOSE AND WILL TAKE A
BLEND OF MAV/ECMWF MOS THROUGH THE EXTENDED PERIODS.
ATWELL
&&
.PREV DISCUSSION... /ISSUED 137 AM EST MON DEC 17 2012/
AVIATION...
06Z UPDATE...
PRIMARY CONCERN IS DEVELOPMENT OF LIFR CIGS AND VSBYS THIS
MORNING AND TSRA LIKELIHOOD THIS AFTERNOON. CIGS AND VSBYS NOW
FALLING QUICKLY AS PRECIP HAS ENDED AND MOIST SFC AND RADIATIONAL
COOLING IS ENHANCING STRATUS LAYER. LIFR LIKELY TO PERSIST THROUGH
15Z WHEN NEXT BAND OF PRECIP TO MOVE IN. TSRA MORE LIKELY TODAY
THAN LAST 24 HRS WITH BETTER INSTABILITY. WILL UP CHCS TO TEMPO
FOR TSRA BETWEEN 16-22Z AT ATL AND SIMILAR TIMES AT OTHER TAF
SITES. SE WINDS WILL SHIFT TO SSW AROUND WHEN PRECIP STARTS IN THE
LATE MORNING. CLOUDS AND PRECIP WILL KEEP SPEEDS FROM GETTING TOO
STRONG BUT BY MID AFTERNOON...COULD SEE A FEW GUSTS OF 15-18KTS.
PRECIP SHOULD END BY 00Z.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON TSRA TIMING.
HIGH ON ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 62 47 62 36 / 80 10 5 5
ATLANTA 64 47 61 41 / 90 10 5 5
BLAIRSVILLE 57 41 56 29 / 90 10 5 5
CARTERSVILLE 63 42 59 32 / 100 10 5 5
COLUMBUS 69 50 65 40 / 80 10 5 5
GAINESVILLE 60 45 60 39 / 90 10 5 5
MACON 70 49 66 35 / 80 20 5 5
ROME 64 41 60 33 / 90 10 5 5
PEACHTREE CITY 66 42 62 32 / 90 10 5 5
VIDALIA 74 56 69 42 / 80 40 0 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....ATWELL
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
158 PM CST MON DEC 17 2012
.DISCUSSION...
1215 PM CST
SOME SMALL CHANGES MADE TO THE AFTERNOON FORECAST...MAINLY TO
INHIBIT TEMPS A FEW DEGREES AND TO INCLUDE THE MENTION OF SNOW IN
THE SOUTHEAST FORECAST AREA. WELL-DEFINED UPPER WAVE IS MOVING ENE
OVER THE LOWER OHIO VALLEY EARLY THIS AFTERNOON. A FAIRLY
IMPRESSIVE UPPER LEVEL TEMPERATURE GRADIENT EXISTS ON THE NORTH
AND NORTHWEST SIDE OF THIS SYSTEM...AND WITH THE SYSTEM ITSELF
STILL INTENSIFYING...THIS AREA IS FAVORED FOR FRONTOGENESIS AND
POTENTIALLY ENHANCED PRECIP ENOUGH TO OVERCOME A DRY PART OF THE
COLUMN. SURE ENOUGH...RADAR ECHOES HAVE BEEN INCREASING ACROSS
CENTRAL IL AND THE SOUTHEAST FORECAST AREA. WITH MARGINAL WET BULB
TEMPERATURES...A POTENTIAL FOR WET BIG-FLAKED SNOW EXISTS. THIS
HAS ALREADY BEEN OBSERVED IN LINCOLN /AAA/. BOTH THE RAP AND NAM
INDICATE OMEGA WITHIN THE DENDRITIC GROWTH AREA LIKELY AIDING IN
LARGER FLAKES THAT ARE LESS SUSCEPTIBLE TO MELT/SUBLIMATE ON THEIR
WAY DOWNWARD. THESE MODELS INDICATE THIS FORCING NEAR -15C TO
CONTINUE THROUGH MID-AFTERNOON...WHICH MAKES SENSE ON THE SYNOPTIC
SCALE WITH THE PATH AND EVOLUTION OF THE SYSTEM. A DUSTING COULD
HAPPEN BUT OVERALL NO REAL ACCUMULATION EXPECTED.
EARLY LOOK AT 12Z GUIDANCE FOR THE UPCOMING SNOW EVENT INDICATES
NO DRAMATIC SHIFTS...HOWEVER PLENTY OF INTERESTING FEATURES ARE
EVIDENT. THE NAM/GFS/SREF CONTINUE TO FAVOR A MORE NORTHWARD TRACK
OF THE PANHANDLE HOOK...WITH THE EC AND GEM SOUTH. THIS RESULTS
IN DRASTIC DIFFERENCES IN THERMAL PROFILES AND SNOWFALL DURATION
AND THUS ACCUMULATION ACROSS A LARGE PART OF THE AREA. MOST OF THE
GUIDANCE AGREES ON IMPRESSIVELY STRONG WINDS CORRELATING WITH THE
COLUMN COOLING ON THU AFTERNOON AND EVE. THE GENERAL IDEA REMAINS
STRONG TO HAVE SOME RAIN INDICATED WEDNESDAY NIGHT INTO THURSDAY
MORNING IN THE FORECAST AND THEN TRENDING MORE TOWARD SNOW AND
BLOWING SNOW.
MTF/RC
//PREV DISCUSSION...
337 AM CST
FORECAST CONCERNS FOCUS MAINLY ON A COUPLE OF CHANCES FOR SOME LIGHT
PRECIPITATION ACROSS PORTIONS OF THE CWA LATER TODAY/THIS EVENING
AND AGAIN TUESDAY...WITH ATTENTION THEN QUICKLY TURNING TO THE
POTENTIAL FOR A STRONG WINTER STORM FOR THE UPPER MIDWEST WEDNESDAY
NIGHT THROUGH THURSDAY.
SURFACE LOW PRESSURE ACROSS THE NORTHERN GREAT LAKES REGION
CONTINUES TO DRIFT SLOWLY AWAY TO THE NORTHEAST EARLY THIS MORNING.
COLD FRONT WHICH PUSHED ACROSS THE AREA SUNDAY HAS EDGED SOUTHEAST
TO THE OHIO RIVER VALLEY...WHILE WEAK HIGH PRESSURE HAS SPREAD INTO
ILLINOIS FROM THE WEST. LOOKING ALOFT...BROAD TROUGHING LINGERS
ACROSS THE CENTRAL CONUS TO THE SOUTH OF A CLOSED UPPER LOW OVER
WESTERN ONTARIO. SLOW PROGRESSION OF FEATURES AND PRESENCE OF
SEVERAL SMALLER AMPLITUDE MID-LEVEL SHORT WAVES HAVE PREVENTED
STRONG DRYING/SUBSIDENCE AND CLEARING OF LOW CLOUDS ACROSS THE
REGION. GOES WATER VAPOR IMAGERY DEPICTS A COUPLE OF SUCH MID-LEVEL
SHORT WAVES UPSTREAM OF THE REGION TODAY...ONE LIFTING OUT OF THE
RED RIVER VALLEY OF THE SOUTH TOWARD THE LOWER OHIO VALLEY...AND
ANOTHER ACROSS THE CENTRAL PLAINS OF NEBRASKA/KANSAS. NEAR-TERM
GUIDANCE ARE IN AGREEMENT IN BRINGING THESE FEATURES EAST ACROSS THE
MID/UPPER MISSISSIPPI AND OHIO VALLEYS THROUGH THIS EVENING. MAIN
FOCUS FOR MEASURABLE PRECIPITATION SHOULD REMAIN LARGELY WITH WEAK
SURFACE LOW REFLECTION WHICH PROPAGATES ALONG THE AFOREMENTIONED LOW
LEVEL BAROCLINIC ZONE ALONG THE OHIO RIVER...THOUGH VARIOUS GUIDANCE
INCLUDING THE GFS/ECMWF/SREF AND GEM ALL INDICATE A LITTLE LIGHT QPF
STREAK FROM SOUTHEAST KS ACROSS CENTRAL MO AND INTO CENTRAL IL WHICH
INCLUDES OUR FAR SOUTHERN COUNTIES IN ASSOCIATION WITH THE CENTRAL
PLAINS VORT AND POCKET OF MID-LEVEL MOISTURE. ALREADY SEEING SOME
LIGHT RADAR RETURNS ACROSS SOUTHERN KS AT THIS HOUR...WHICH GUIDANCE
SUGGESTS WOULD AFFECT PARTS OF THE WFO LOT CWA ROUGHLY SOUTH OF A
PONTIAC-VALPARAISO LINE THIS AFTERNOON AND EARLY EVENING. LOW LEVEL
THERMAL/MOISTURE PROFILES SUGGEST THIS WOULD MAINLY BE LIGHT
RAIN/SPRINKLES...WITH PRECIP EXPECTED TO END THIS EVENING BEFORE LOW
LEVEL THICKNESS DECREASES ENOUGH FOR MIXED PRECIP.
STRONG UPPER JET STREAK NOTED IN 00Z RAOB ANALYSIS CURRENTLY PUSHING
ACROSS THE OREGON COAST IS PROJECTED TO SPREAD ACROSS THE CENTRAL
CONUS TONIGHT...INDUCING LOW PRESSURE DEVELOPMENT ACROSS THE
NORTHERN PLAINS/UPPER MIDWEST. GUIDANCE DEPICTS WEAK SURFACE LOW
PRESSURE MOVING ALONG THE IL/WI BORDER AREA TUESDAY AFTERNOON...
WITH REGION OF WARM ADVECTION AND RESULTANT ASCENT FOCUSED ACROSS
SOUTHERN WI/FAR NORTHERN IL. ISENTROPIC PROGS IN 290-295 K LAYER
INDICATE A PERIOD OF SATURATION AND FAIRLY GOOD CONVERGENCE ACROSS
THE NORTHERN PARTS OF THE CWA TUESDAY MORNING...WITH SEVERAL
GUIDANCE SETS PRODUCING A LITTLE LIGHT QPF. WHILE NOT EXPECTED TO
AMOUNT TO MUCH...THERMAL PROFILES EARLY TUESDAY DO INDICATE THE
POTENTIAL FOR A LITTLE LIGHT SNOW TO MIX/CHANGE TO LIGHT RAIN DURING
THE MORNING HOURS...BEFORE LARGELY SHIFTING NORTHEAST ACROSS WI/LAKE
MICHIGAN. HAVE ONLY CARRIED SLIGHT CHANCE POPS FOR LIGHT PRECIP OVER
NORTHERN IL...WITH A LITTLE BETTER CHANCE RIGHT ALONG THE WISCONSIN
BORDER.
MEDIUM RANGE GUIDANCE REMAINS REMARKABLY SIMILAR IN AMPLIFYING UPPER
FLOW ACROSS THE CONUS TUESDAY NIGHT INTO WEDNESDAY...AS SYSTEM
CURRENTLY SEEN NEAR 150W 40N IN NORTHERN HEMISPHERIC WATER VAPOR
IMAGERY AMPLIFIES ALONG THE WEST COAST AND INDUCES BROAD DOWNSTREAM
RIDGE ACROSS OUR REGION. GUIDANCE MAINTAINS TREND OF UPPER TROUGH
DIGGING ACROSS THE FOUR CORNERS REGION BY 12Z WEDNESDAY...WITH
SURFACE CYCLOGENESIS OCCURRING OVER THE TX/OK PANHANDLE REGION.
UPPER TROUGH THEN ADVANCES ACROSS THE PLAINS...BECOMING NEGATIVELY
TILTED ACROSS THE MIDWEST AND EVENTUALLY CLOSING OFF THE MID-LEVEL
CIRCULATION OVER THE WESTERN GREAT LAKES ON THURSDAY. THE ASSOCIATED
SURFACE LOW MEANWHILE...DEEPENS AS IT TREKS NORTHEAST ACROSS
MISSOURI AND ILLINOIS LATE WEDNESDAY NIGHT/THURSDAY MORNING AND INTO
LOWER MICHIGAN BY THURSDAY EVENING. WHILE MODEL SOLUTIONS HAVE BEEN
FAIRLY STEADY IN THEIR DEPICTION OF THE OVERALL SCENARIO FOR THE
PAST FEW DAYS OF MODEL RUNS...SOME DETAIL DIFFERENCES DO REMAIN WITH
RESPECT TO THE TRACK OF THE SURFACE LOW. 00Z GEFS ENSEMBLE
CLUSTERING HAS TIGHTENED UP FROM ITS 12Z RUN YESTERDAY...WITH A
MEDIAN SOLUTION TRACK JUST SOUTHEAST OF CHICAGO. THE NAM/SREF ARE
THE FARTHEST WEST...ACTUALLY TAKING THE LOW ACROSS FAR NORTHWEST IL.
THE 00Z GEM FOLLOWS A SIMILAR TRACK...THOUGH IS SLOWER BY A GOOD 6+
HOURS. THE 00Z ECMWF IS SIMILAR IN SPEED/TIMING TO THE GEM...THOUGH
TRACKS FARTHER TO THE RIGHT ALONG A DANVILLE-GOSHEN LINE...OR ABOUT
50 MILES WEST OF THE 12Z ECMWF TRACK. OFTEN...DEEPENING NEGATIVELY
TILTED STORM SYSTEMS EMERGING FROM THE SOUTHWEST TEND TO BE
DEEPER...SLOWER AND TRACK FARTHER TO THE WEST/NORTHWEST THAN MODELS
INITIALLY FORECAST...SO PERHAPS IT IS NOT TOO SURPRISING TO SEE THE
ECMWF TREND BACK NORTHWEST JUST A BIT. AT THIS POINT...HAVE BASED
FORECAST ALONG THE LINES OF A 00Z GEM/00Z ECMWF BLEND ALLOWING FOR
THE SLOWER TIMING OF THESE TWO SOLUTIONS...WITH A LOW TRACK THAT AT
LEAST INITIALLY WRAPS WARMER AIR AND RAIN INTO THE EASTERN HALF OF
THE CWA. THUS HAVE MAINTAINED A PROGRESSION OF RAIN/SNOW
NORTHWEST...RAIN EAST...EVENTUALLY CHANGING TO ALL SNOW AS THE LOW
PASSES THURSDAY AND COLD AIR WRAPS INTO THE DEPARTING LOW. WILL
CONTINUE TO HIGHLIGHT THE POTENTIAL FOR A SIGNIFICANT STORM ACROSS
THE REGION IN THE HWO...THOUGH STILL A BIT EARLY TO NAIL DOWN WHERE
SPECIFIC SNOW AMOUNTS WOULD FALL EXCEPT THE CONCEPT OF MORE ACROSS
THE NORTHWEST PART OF THE CWA AND SIGNIFICANTLY LESS IN THE
SOUTHEAST. IN ADDITION TO THE POTENTIAL FOR SNOW...VERY WINDY
CONDITIONS ARE ANTICIPATED BY THURSDAY NIGHT...AS THE DEEPENING LOW
MOVES INTO LOWER MICHIGAN...WITH NORTHWEST WINDS POTENTIALLY GUSTING
INTO THE 45 MPH RANGE.
A BRIEF PERIOD OF COLDER BUT QUIET WEATHER MOVES INTO THE AREA
FRIDAY THROUGH THE WEEKEND...WITH SOME LINGERING SNOW SHOWERS
DOWNWIND OF LAKE MICHIGAN INTO INDIANA/MICHIGAN.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* HOW LATE INTO NIGHT MVFR CEILINGS WILL HOLD ON BEFORE
CLEARING...OR POSSIBLY NOT CLEARING AND PERSISTING THROUGH THE
NIGHT.
TRS
//DISCUSSION...UPDATED 18Z...
WIDESPREAD MVFR STRATUS ACROSS THE REGION WITH CEILINGS DOWN TO
IFR WELL OFF TO THE W THROUGH NW ACROSS IA...MN AND SE WI. VERY
WEEK PRESSURE GRADIENT ACROSS THE REGION SO LOW LEVEL FLOW IS IF
NOT NIL THEN VERY LIGHT. AS THE AFTERNOON PROGRESSES AND THROUGH
THE EVENING A WEAK RIDGE OF HIGH PRESSURE WILL BUILD SE FROM MN
AND WI TO OVER THE LOCAL AREA. WINDS SHOULD GENERALLY FAVOR A NW
TO N DIRECTION BUT REMAIN IN THE 3 TO 6 KT RANGE AND THEN BECOME
LIGHT AND VARIABLE OR CALM AGAIN AS THE RIDGE AXIS SETTLES OVER
THE LOCAL TERMINALS TONIGHT.
BY 12Z TUE LOW PRESSURE IS TO HAVE MOVED E FROM THE CENTRAL
PLAINS TO AROUND THE WESTERN IA AREA. IN RESPONSE WINDS BY
DAYBREAK SHOULD HAVE TURNED TO OUT SSE AS THE LOW CONTINUES TO
APPROACH THE AREA FROM THE W.
THERE IS A SLIGHT CHANCE OF SOME VERY LIGHT PRECIPITATION DURING
THU ACROSS NORTHERN IL THOUGH MODELS INDICATING SIGNIFICANT
SATURATION PRESSURE DEFICITS PERSIST WHILE BEST ISENTROPIC
UPGLIDE/OMEGA MOVE OVER THE AREA DURING THE MORNING LEAVING
BETTER CHANCE OF LIGHT SNOWFALL ACROSS SOUTHERN MN AND CENTRAL
WI.
MODEL THERMAL PROFILES AND MOS GUIDANCE ALL SUGGESTING THAT THE
LOW LEVEL INVERSION WILL WEAKEN AND THE STRATUS CLOUDS WILL
DISSIPATE DURING THE NIGHT WHILE MID LEVEL CLOUDS SPREAD OVER THE
AREA AHEAD OF A SHORT WAVE CURRENTLY OVER ID MOVES E TO THE
PLAINS OVERNIGHT.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN NIL/LIGHT AND VARIABLE WINDS REST OF
AFTERNOON AND TONIGHT.
* HIGH CONFIDENCE CEILINGS WILL REMAIN AOA 015 THRESHOLD REST OF
DAY AND FIRST PART OF EVENING.
* MODERATE CONFIDENCE STRATUS DECK WILL DISSIPATE BUT CONFIDENCE
IN TIMING OF ITS OCCURRENCE DURING THE OVERNIGHT IS LOW.
* HIGH CONFIDENCE THAT NO SIGNIFICANT PRECIPITATION WILL FALL OVER
THE LOCAL AREA TUE A.M.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
* TUESDAY NIGHT AND WEDNESDAY...VFR.
* WEDNESDAY NIGHT...RAIN DEVELOPING. IFR POSSIBLE.
* THURSDAY...RAIN CHANGING TO SNOW. IFR/LIFR LIKELY. BECOMING
VERY WINDY WITH GUSTS 35+ KTS BY EVENING.
* THURSDAY NIGHT...VERY WINDY WITH GUSTS 35+ KT. SNOW ENDING.
BLOWING SNOW. LIFR IMPROVING TO MVFR.
* FRIDAY...GUSTY NORTHWEST WINDS. VFR.
* SATURDAY AND SUNDAY...VFR.
&&
.MARINE...
312 AM...NORTHWEST STORM FORCE WINDS TO 50 KT NOW EXPECTED BY
LATE THURSDAY AFTERNOON AND CONTINUING INTO THURSDAY NIGHT.
MAIN FORECAST CONCERN/CHALLENGE REMAINS THE POWERFUL WINTER STORM
EXPECTED TO MOVE ACROSS THE GREAT LAKES REGION THURSDAY/THURSDAY
NIGHT. THERE REMAINS UNCERTAINTY REGARDING THE EXACT TRACK OF THE
LOW FROM THE VARIOUS FORECAST MODELS THOUGH THERE IS SOME
CONSENSUS THAT THIS STORM WILL TRACK VERY CLOSE TO OR PERHAPS OVER
SOUTHERN LAKE MICHIGAN. THE STORM WILL BE IN THE PROCESS OF
RAPIDLY DEEPENING DURING THIS TIME. IF THIS STORM DOES INDEED
FOLLOW THIS TRACK...WINDS WILL RAPIDLY INCREASE THURSDAY
AFTERNOON AND CONTINUE INTO THURSDAY NIGHT WITH FORECAST SOUNDINGS
SHOWING GUSTS INTO THE 45-50KT RANGE WHICH COULD BE TOO LOW THOUGH
STRONGEST WINDS PROBABLY WOULD ONLY LAST 4-8 HOURS THOUGH GALES
SHOULD PERSIST WELL INTO FRIDAY AS THEY SLOWLY RELAX INTO FRIDAY
EVENING.
IN THE SHORTER TERM...LOW PRESSURE OVER THE NORTHERN LAKES WILL
LIFT NORTH TODAY AND WEAKEN...THIS WILL MAINTAIN A MODEST WESTERLY
GRADIENT OVER THE NORTHERN HALF OF THE LAKE THIS MORNING. WINDS
WILL TURN NORTHERLY OVER THE SOUTH END OF THE LAKE AHEAD OF A WEAK
RIDGE OF HIGH PRESSURE WHICH WILL MOVE ACROSS THE WESTERN LAKES
OVERNIGHT. ANOTHER LOW WILL BE MOVING NORTHEAST ACROSS THE OHIO
VALLEY THIS AFTERNOON AND DEEPENING AS IT MOVES TOWARD NEW ENGLAND
ON TUESDAY. SO HOW STRONG THE NORTHERLY GRADIENT BECOMES ON THE
SOUTH END OF THE LAKE LATER TODAY WILL NEED TO BE MONITORED.
ANOTHER FAST MOVING LOW WILL MOVE ACROSS THE IL/WI REGION ON
TUESDAY AND THEN ACROSS SOUTHERN LAKE MICHIGAN TUESDAY EVENING.
THE GRADIENT MAY INCREASE ENOUGH TO SUPPORT 15-25 KT ON THE FAR
SOUTH END OF THE LAKE AHEAD OF THE LOW AND AGAIN FROM THE WEST
TUESDAY EVENING AS THE LOW PASSES. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1230 PM CST MON DEC 17 2012
.DISCUSSION...
1215 PM CST
SOME SMALL CHANGES MADE TO THE AFTERNOON FORECAST...MAINLY TO
INHIBIT TEMPS A FEW DEGREES AND TO INCLUDE THE MENTION OF SNOW IN
THE SOUTHEAST FORECAST AREA. WELL-DEFINED UPPER WAVE IS MOVING ENE
OVER THE LOWER OHIO VALLEY EARLY THIS AFTERNOON. A FAIRLY
IMPRESSIVE UPPER LEVEL TEMPERATURE GRADIENT EXISTS ON THE NORTH
AND NORTHWEST SIDE OF THIS SYSTEM...AND WITH THE SYSTEM ITSELF
STILL INTENSIFYING...THIS AREA IS FAVORED FOR FRONTOGENESIS AND
POTENTIALLY ENHANCED PRECIP ENOUGH TO OVERCOME A DRY PART OF THE
COLUMN. SURE ENOUGH...RADAR ECHOES HAVE BEEN INCREASING ACROSS
CENTRAL IL AND THE SOUTHEAST FORECAST AREA. WITH MARGINAL WET BULB
TEMPERATURES...A POTENTIAL FOR WET BIG-FLAKED SNOW EXISTS. THIS
HAS ALREADY BEEN OBSERVED IN LINCOLN /AAA/. BOTH THE RAP AND NAM
INDICATE OMEGA WITHIN THE DENDRITIC GROWTH AREA LIKELY AIDING IN
LARGER FLAKES THAT ARE LESS SUSCEPTIBLE TO MELT/SUBLIMATE ON THEIR
WAY DOWNWARD. THESE MODELS INDICATE THIS FORCING NEAR -15C TO
CONTINUE THROUGH MID-AFTERNOON...WHICH MAKES SENSE ON THE SYNOPTIC
SCALE WITH THE PATH AND EVOLUTION OF THE SYSTEM. A DUSTING COULD
HAPPEN BUT OVERALL NO REAL ACCUMULATION EXPECTED.
EARLY LOOK AT 12Z GUIDANCE FOR THE UPCOMING SNOW EVENT INDICATES
NO DRAMATIC SHIFTS...HOWEVER PLENTY OF INTERESTING FEATURES ARE
EVIDENT. THE NAM/GFS/SREF CONTINUE TO FAVOR A MORE NORTHWARD TRACK
OF THE PANHANDLE HOOK...WITH THE EC AND GEM SOUTH. THIS RESULTS
IN DRASTIC DIFFERENCES IN THERMAL PROFILES AND SNOWFALL DURATION
AND THUS ACCUMULATION ACROSS A LARGE PART OF THE AREA. MOST OF THE
GUIDANCE AGREES ON IMPRESSIVELY STRONG WINDS CORRELATING WITH THE
COLUMN COOLING ON THU AFTERNOON AND EVE. THE GENERAL IDEA REMAINS
STRONG TO HAVE SOME RAIN INDICATED WEDNESDAY NIGHT INTO THURSDAY
MORNING IN THE FORECAST AND THEN TRENDING MORE TOWARD SNOW AND
BLOWING SNOW.
MTF/RC
&&
.PREV DISCUSSION...
337 AM CST
FORECAST CONCERNS FOCUS MAINLY ON A COUPLE OF CHANCES FOR SOME LIGHT
PRECIPITATION ACROSS PORTIONS OF THE CWA LATER TODAY/THIS EVENING
AND AGAIN TUESDAY...WITH ATTENTION THEN QUICKLY TURNING TO THE
POTENTIAL FOR A STRONG WINTER STORM FOR THE UPPER MIDWEST WEDNESDAY
NIGHT THROUGH THURSDAY.
SURFACE LOW PRESSURE ACROSS THE NORTHERN GREAT LAKES REGION
CONTINUES TO DRIFT SLOWLY AWAY TO THE NORTHEAST EARLY THIS MORNING.
COLD FRONT WHICH PUSHED ACROSS THE AREA SUNDAY HAS EDGED SOUTHEAST
TO THE OHIO RIVER VALLEY...WHILE WEAK HIGH PRESSURE HAS SPREAD INTO
ILLINOIS FROM THE WEST. LOOKING ALOFT...BROAD TROUGHING LINGERS
ACROSS THE CENTRAL CONUS TO THE SOUTH OF A CLOSED UPPER LOW OVER
WESTERN ONTARIO. SLOW PROGRESSION OF FEATURES AND PRESENCE OF
SEVERAL SMALLER AMPLITUDE MID-LEVEL SHORT WAVES HAVE PREVENTED
STRONG DRYING/SUBSIDENCE AND CLEARING OF LOW CLOUDS ACROSS THE
REGION. GOES WATER VAPOR IMAGERY DEPICTS A COUPLE OF SUCH MID-LEVEL
SHORT WAVES UPSTREAM OF THE REGION TODAY...ONE LIFTING OUT OF THE
RED RIVER VALLEY OF THE SOUTH TOWARD THE LOWER OHIO VALLEY...AND
ANOTHER ACROSS THE CENTRAL PLAINS OF NEBRASKA/KANSAS. NEAR-TERM
GUIDANCE ARE IN AGREEMENT IN BRINGING THESE FEATURES EAST ACROSS THE
MID/UPPER MISSISSIPPI AND OHIO VALLEYS THROUGH THIS EVENING. MAIN
FOCUS FOR MEASURABLE PRECIPITATION SHOULD REMAIN LARGELY WITH WEAK
SURFACE LOW REFLECTION WHICH PROPAGATES ALONG THE AFOREMENTIONED LOW
LEVEL BAROCLINIC ZONE ALONG THE OHIO RIVER...THOUGH VARIOUS GUIDANCE
INCLUDING THE GFS/ECMWF/SREF AND GEM ALL INDICATE A LITTLE LIGHT QPF
STREAK FROM SOUTHEAST KS ACROSS CENTRAL MO AND INTO CENTRAL IL WHICH
INCLUDES OUR FAR SOUTHERN COUNTIES IN ASSOCIATION WITH THE CENTRAL
PLAINS VORT AND POCKET OF MID-LEVEL MOISTURE. ALREADY SEEING SOME
LIGHT RADAR RETURNS ACROSS SOUTHERN KS AT THIS HOUR...WHICH GUIDANCE
SUGGESTS WOULD AFFECT PARTS OF THE WFO LOT CWA ROUGHLY SOUTH OF A
PONTIAC-VALPARAISO LINE THIS AFTERNOON AND EARLY EVENING. LOW LEVEL
THERMAL/MOISTURE PROFILES SUGGEST THIS WOULD MAINLY BE LIGHT
RAIN/SPRINKLES...WITH PRECIP EXPECTED TO END THIS EVENING BEFORE LOW
LEVEL THICKNESS DECREASES ENOUGH FOR MIXED PRECIP.
STRONG UPPER JET STREAK NOTED IN 00Z RAOB ANALYSIS CURRENTLY PUSHING
ACROSS THE OREGON COAST IS PROJECTED TO SPREAD ACROSS THE CENTRAL
CONUS TONIGHT...INDUCING LOW PRESSURE DEVELOPMENT ACROSS THE
NORTHERN PLAINS/UPPER MIDWEST. GUIDANCE DEPICTS WEAK SURFACE LOW
PRESSURE MOVING ALONG THE IL/WI BORDER AREA TUESDAY AFTERNOON...
WITH REGION OF WARM ADVECTION AND RESULTANT ASCENT FOCUSED ACROSS
SOUTHERN WI/FAR NORTHERN IL. ISENTROPIC PROGS IN 290-295 K LAYER
INDICATE A PERIOD OF SATURATION AND FAIRLY GOOD CONVERGENCE ACROSS
THE NORTHERN PARTS OF THE CWA TUESDAY MORNING...WITH SEVERAL
GUIDANCE SETS PRODUCING A LITTLE LIGHT QPF. WHILE NOT EXPECTED TO
AMOUNT TO MUCH...THERMAL PROFILES EARLY TUESDAY DO INDICATE THE
POTENTIAL FOR A LITTLE LIGHT SNOW TO MIX/CHANGE TO LIGHT RAIN DURING
THE MORNING HOURS...BEFORE LARGELY SHIFTING NORTHEAST ACROSS WI/LAKE
MICHIGAN. HAVE ONLY CARRIED SLIGHT CHANCE POPS FOR LIGHT PRECIP OVER
NORTHERN IL...WITH A LITTLE BETTER CHANCE RIGHT ALONG THE WISCONSIN
BORDER.
MEDIUM RANGE GUIDANCE REMAINS REMARKABLY SIMILAR IN AMPLIFYING UPPER
FLOW ACROSS THE CONUS TUESDAY NIGHT INTO WEDNESDAY...AS SYSTEM
CURRENTLY SEEN NEAR 150W 40N IN NORTHERN HEMISPHERIC WATER VAPOR
IMAGERY AMPLIFIES ALONG THE WEST COAST AND INDUCES BROAD DOWNSTREAM
RIDGE ACROSS OUR REGION. GUIDANCE MAINTAINS TREND OF UPPER TROUGH
DIGGING ACROSS THE FOUR CORNERS REGION BY 12Z WEDNESDAY...WITH
SURFACE CYCLOGENESIS OCCURRING OVER THE TX/OK PANHANDLE REGION.
UPPER TROUGH THEN ADVANCES ACROSS THE PLAINS...BECOMING NEGATIVELY
TILTED ACROSS THE MIDWEST AND EVENTUALLY CLOSING OFF THE MID-LEVEL
CIRCULATION OVER THE WESTERN GREAT LAKES ON THURSDAY. THE ASSOCIATED
SURFACE LOW MEANWHILE...DEEPENS AS IT TREKS NORTHEAST ACROSS
MISSOURI AND ILLINOIS LATE WEDNESDAY NIGHT/THURSDAY MORNING AND INTO
LOWER MICHIGAN BY THURSDAY EVENING. WHILE MODEL SOLUTIONS HAVE BEEN
FAIRLY STEADY IN THEIR DEPICTION OF THE OVERALL SCENARIO FOR THE
PAST FEW DAYS OF MODEL RUNS...SOME DETAIL DIFFERENCES DO REMAIN WITH
RESPECT TO THE TRACK OF THE SURFACE LOW. 00Z GEFS ENSEMBLE
CLUSTERING HAS TIGHTENED UP FROM ITS 12Z RUN YESTERDAY...WITH A
MEDIAN SOLUTION TRACK JUST SOUTHEAST OF CHICAGO. THE NAM/SREF ARE
THE FARTHEST WEST...ACTUALLY TAKING THE LOW ACROSS FAR NORTHWEST IL.
THE 00Z GEM FOLLOWS A SIMILAR TRACK...THOUGH IS SLOWER BY A GOOD 6+
HOURS. THE 00Z ECMWF IS SIMILAR IN SPEED/TIMING TO THE GEM...THOUGH
TRACKS FARTHER TO THE RIGHT ALONG A DANVILLE-GOSHEN LINE...OR ABOUT
50 MILES WEST OF THE 12Z ECMWF TRACK. OFTEN...DEEPENING NEGATIVELY
TILTED STORM SYSTEMS EMERGING FROM THE SOUTHWEST TEND TO BE
DEEPER...SLOWER AND TRACK FARTHER TO THE WEST/NORTHWEST THAN MODELS
INITIALLY FORECAST...SO PERHAPS IT IS NOT TOO SURPRISING TO SEE THE
ECMWF TREND BACK NORTHWEST JUST A BIT. AT THIS POINT...HAVE BASED
FORECAST ALONG THE LINES OF A 00Z GEM/00Z ECMWF BLEND ALLOWING FOR
THE SLOWER TIMING OF THESE TWO SOLUTIONS...WITH A LOW TRACK THAT AT
LEAST INITIALLY WRAPS WARMER AIR AND RAIN INTO THE EASTERN HALF OF
THE CWA. THUS HAVE MAINTAINED A PROGRESSION OF RAIN/SNOW
NORTHWEST...RAIN EAST...EVENTUALLY CHANGING TO ALL SNOW AS THE LOW
PASSES THURSDAY AND COLD AIR WRAPS INTO THE DEPARTING LOW. WILL
CONTINUE TO HIGHLIGHT THE POTENTIAL FOR A SIGNIFICANT STORM ACROSS
THE REGION IN THE HWO...THOUGH STILL A BIT EARLY TO NAIL DOWN WHERE
SPECIFIC SNOW AMOUNTS WOULD FALL EXCEPT THE CONCEPT OF MORE ACROSS
THE NORTHWEST PART OF THE CWA AND SIGNIFICANTLY LESS IN THE
SOUTHEAST. IN ADDITION TO THE POTENTIAL FOR SNOW...VERY WINDY
CONDITIONS ARE ANTICIPATED BY THURSDAY NIGHT...AS THE DEEPENING LOW
MOVES INTO LOWER MICHIGAN...WITH NORTHWEST WINDS POTENTIALLY GUSTING
INTO THE 45 MPH RANGE.
A BRIEF PERIOD OF COLDER BUT QUIET WEATHER MOVES INTO THE AREA
FRIDAY THROUGH THE WEEKEND...WITH SOME LINGERING SNOW SHOWERS
DOWNWIND OF LAKE MICHIGAN INTO INDIANA/MICHIGAN.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LENGTH OF TIME MVFR AND LOCALIZED IFR CEILINGS WILL HOLD ON
INTO THE EVENING/TONIGHT AND IF WILL REMAIN AOA 015 THRESHOLD
WHICH HAS OPERATIONAL IMPACTS ON ORD AND MDW TRAFFIC.
TRS
//DISCUSSION...UPDATED 18Z...
WIDESPREAD MVFR STRATUS ACROSS THE REGION WITH CEILINGS DOWN TO
IFR WELL OFF TO THE W THROUGH NW ACROSS IA...MN AND SE WI. VERY
WEEK PRESSURE GRADIENT ACROSS THE REGION SO LOW LEVEL FLOW IS IF
NOT NIL THEN VERY LIGHT. AS THE AFTERNOON PROGRESSES AND THROUGH
THE EVENING A WEAK RIDGE OF HIGH PRESSURE WILL BUILD SE FROM MN
AND WI TO OVER THE LOCAL AREA. WINDS SHOULD GENERALLY FAVOR A NW
TO N DIRECTION BUT REMAIN IN THE 3 TO 6 KT RANGE AND THEN BECOME
LIGHT AND VARIABLE OR CALM AGAIN AS THE RIDGE AXIS SETTLES OVER
THE LOCAL TERMINALS TONIGHT.
BY 12Z TUE LOW PRESSURE IS TO HAVE MOVED E FROM THE CENTRAL
PLAINS TO AROUND THE WESTERN IA AREA. IN RESPONSE WINDS BY
DAYBREAK SHOULD HAVE TURNED TO OUT SSE AS THE LOW CONTINUES TO
APPROACH THE AREA FROM THE W.
THERE IS A SLIGHT CHANCE OF SOME VERY LIGHT PRECIPITATION DURING
THU ACROSS NORTHERN IL THOUGH MODELS INDICATING SIGNIFICANT
SATURATION PRESSURE DEFICITS PERSIST WHILE BEST ISENTROPIC
UPGLIDE/OMEGA MOVE OVER THE AREA DURING THE MORNING LEAVING
BETTER CHANCE OF LIGHT SNOWFALL ACROSS SOUTHERN MN AND CENTRAL
WI.
MODEL THERMAL PROFILES AND MOS GUIDANCE ALL SUGGESTING THAT THE
LOW LEVEL INVERSION WILL WEAKEN AND THE STRATUS CLOUDS WILL
DISSIPATE DURING THE NIGHT WHILE MID LEVEL CLOUDS SPREAD OVER THE
AREA AHEAD OF A SHORT WAVE CURRENTLY OVER ID MOVES E TO THE
PLAINS OVERNIGHT.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN NIL/LIGHT AND VARIABLE WINDS INTO THE NIGHT.
* HIGH CONFIDENCE CEILINGS WILL REMAIN AOA 015 THRESHOLD REST OF
DAY.
* MODERATE CONFIDENCE STRATUS DECK WILL DISSIPATE BUT CONFIDENCE
IN TIMING DURING THE OVERNIGHT IS LOW.
* HIGH CONFIDENCE THAT NO SIGNIFICANT PRECIPITATION WILL FALL OVER
THE LOCAL AREA.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
* TUESDAY NIGHT AND WEDNESDAY...VFR.
* WEDNESDAY NIGHT...RAIN DEVELOPING. IFR POSSIBLE.
* THURSDAY...RAIN CHANGING TO SNOW. IFR/LIFR LIKELY. BECOMING
VERY WINDY WITH GUSTS 35+ KTS BY EVENING.
* THURSDAY NIGHT...VERY WINDY WITH GUSTS 35+ KT. SNOW ENDING.
BLOWING SNOW. LIFR IMPROVING TO MVFR.
* FRIDAY...GUSTY NORTHWEST WINDS. VFR.
* SATURDAY AND SUNDAY...VFR.
&&
.MARINE...
312 AM...NORTHWEST STORM FORCE WINDS TO 50 KT NOW EXPECTED BY
LATE THURSDAY AFTERNOON AND CONTINUING INTO THURSDAY NIGHT.
MAIN FORECAST CONCERN/CHALLENGE REMAINS THE POWERFUL WINTER STORM
EXPECTED TO MOVE ACROSS THE GREAT LAKES REGION THURSDAY/THURSDAY
NIGHT. THERE REMAINS UNCERTAINTY REGARDING THE EXACT TRACK OF THE
LOW FROM THE VARIOUS FORECAST MODELS THOUGH THERE IS SOME
CONSENSUS THAT THIS STORM WILL TRACK VERY CLOSE TO OR PERHAPS OVER
SOUTHERN LAKE MICHIGAN. THE STORM WILL BE IN THE PROCESS OF
RAPIDLY DEEPENING DURING THIS TIME. IF THIS STORM DOES INDEED
FOLLOW THIS TRACK...WINDS WILL RAPIDLY INCREASE THURSDAY
AFTERNOON AND CONTINUE INTO THURSDAY NIGHT WITH FORECAST SOUNDINGS
SHOWING GUSTS INTO THE 45-50KT RANGE WHICH COULD BE TOO LOW THOUGH
STRONGEST WINDS PROBABLY WOULD ONLY LAST 4-8 HOURS THOUGH GALES
SHOULD PERSIST WELL INTO FRIDAY AS THEY SLOWLY RELAX INTO FRIDAY
EVENING.
IN THE SHORTER TERM...LOW PRESSURE OVER THE NORTHERN LAKES WILL
LIFT NORTH TODAY AND WEAKEN...THIS WILL MAINTAIN A MODEST WESTERLY
GRADIENT OVER THE NORTHERN HALF OF THE LAKE THIS MORNING. WINDS
WILL TURN NORTHERLY OVER THE SOUTH END OF THE LAKE AHEAD OF A WEAK
RIDGE OF HIGH PRESSURE WHICH WILL MOVE ACROSS THE WESTERN LAKES
OVERNIGHT. ANOTHER LOW WILL BE MOVING NORTHEAST ACROSS THE OHIO
VALLEY THIS AFTERNOON AND DEEPENING AS IT MOVES TOWARD NEW ENGLAND
ON TUESDAY. SO HOW STRONG THE NORTHERLY GRADIENT BECOMES ON THE
SOUTH END OF THE LAKE LATER TODAY WILL NEED TO BE MONITORED.
ANOTHER FAST MOVING LOW WILL MOVE ACROSS THE IL/WI REGION ON
TUESDAY AND THEN ACROSS SOUTHERN LAKE MICHIGAN TUESDAY EVENING.
THE GRADIENT MAY INCREASE ENOUGH TO SUPPORT 15-25 KT ON THE FAR
SOUTH END OF THE LAKE AHEAD OF THE LOW AND AGAIN FROM THE WEST
TUESDAY EVENING AS THE LOW PASSES. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1157 AM CST MON DEC 17 2012
.DISCUSSION...
ISSUED 1040 AM CST MON DEC 17 2012
UPDATING THE FORECAST TO INCREASE RAIN CHANCES TODAY SE OF THE IL RIVER
WITH LIKELY POPS AND ALSO COOLING THE HIGHS A BIT WITH LOW CLOUDS
LINGERING ALL DAY. SLEET MAY BE MIXED IN WITH THE RAIN LATE THIS
MORNING NORTH OF I-72. JUST HAD A REPORT OF SLEET WITH THE RAIN AT
MOUNT PULASKI IN SE LOGAN COUNTY AROUND 1030 AM. HIGHS MOSTLY IN
THE LOW TO MID 40S THIS AFTERNOON...RANGING FROM THE UPPER 30S TO
NEAR 40F OVER THE IL RIVER VALLEY IN THE NW TO THE UPPER 40S AND
LOWER 50S NEAR THE WABASH RIVER. THUNDERSTORM CURRENTLY JUST EAST
OF LAWRENCE COUNTY AND LIFTING NE ACROSS SW INDIANA. SPC HAS THUNDERSTORM
CHANCES SE OF I-70 TODAY WHILE SLIGHT RISK OF SEVERE STORM IS OVER
CENTRAL/WESTERN KY...MID TN AND FAR SE INDIANA.
1004 MB LOW PRESSURE ALONG THE KY/IL BORDER BETWEEN EVANSVILLE AND
PADUCAH TO LIFT NE INTO SOUTHERN OH BY THIS EVENING. MEANWHILE A
SHORT WAVE NEAR KC TO MOVE ACROSS SOUTHERN IL THIS EVENING. THIS
TO KEEP A GOOD CHANCE OF RAIN SHOWERS TODAY SE OF THE IL RIVER AND
LINGERING IN EASTERN/SE IL THIS EVENING. NNE WINDS LESS THAN 10
MPH TO TURN NW LATER THIS AFTERNOON AND EVENING.
07
&&
.AVIATION...
ISSUED 1155 AM CST MON DEC 17 2012
IFR TO MVFR VSBYS AND CEILINGS EXPECTED THIS AFTERNOON ACROSS THE
CENTRAL IL TERMINAL AIRPORTS WITH A MIXTURE OF RAIN/SNOW SHOWERS SE
OF THE IL RIVER/PIA. JUST HAVE VCSH AT PIA WITH LIGHT FOG/HAZE 5-6
MILES WHICH WILL BE ON NORTHWEST EDGE OF PRECIPITATION TODAY.
PRECIPITATION SHOULD DIMINISH FROM WEST TO EAST LATER THIS
AFTERNOON AND EARLY EVENING BETWEEN 21Z-03Z. CLOUD BASES OF
500-1500 FT EXPECTED TO ELEVATE TO VFR DURING TONIGHT FROM WEST TO
EAST...THOUGH NOT A CMI IN EASTERN IL UNTIL LATER TONIGHT...AFTER
09Z. 1003 MB LOW PRESSURE DEEPENING A BIT NEAR EVANSVILLE ALONG
THE IN/KY BORDER TO LIFT NE INTO THE MID ATLANTIC STATES BY
06Z/MIDNIGHT TONIGHT. MEANWHILE A SHORT WAVE NEAR KC TO MOVE EAST
ACROSS SOUTHERN IL THIS EVENING...WHILE ANOTHER SHORT WAVE OVER
THE NORTHERN ROCKIES MOVE EAST INTO IA BY 18Z/NOON TUE. MODELS
HAVE BEEN TOO QUICK TO CLEAR OUT LOW CLOUDS AND TOOK A MORE
PESTIMISTIC ROUTE WITH KEEPING LOW CLOUDS AROUND LONGER INTO
TONIGHT. NNE WINDS 4-8 KTS TURNING NW DURING THE AFTERNOON AND
EVENING AND THEN BECOME BREEZY SSW TUE MORNING AHEAD OF 1001 MB
SURFACE LOW PRESSURE MOVING INTO CENTRAL/EASTERN IA BY MIDDAY TUE.
INCREASING WINDS SHOULD LIFT OUT LOW CLOUDS WHILE BAND OF MID
LEVEL CLOUDS POSSIBLE LATE TONIGHT INTO TUE MORNING.
07
&&
.PREV DISCUSSION...
ISSUED 230 AM CST MON DEC 17 2012
PRIMARY FOCUS FOR THIS FORECAST INVOLVES THE MAJOR STORM SYSTEM
THAT WILL BE CROSSING THE MIDWEST WEDNESDAY NIGHT AND THURSDAY...
INCLUDING PRECIPITATION TYPES AND STRONG WINDS. RAIN POTENTIAL
LATER TODAY IS A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH TUESDAY...
MAIN FOCUS FOR ANY RAIN TODAY IS WITH A SURFACE LOW CURRENTLY OVER
SOUTH CENTRAL MISSOURI...WITH A FRONTAL BOUNDARY ARCING NORTHEAST
ALONG THE OHIO RIVER. BEST PRECIPITATION CHANCES WILL BE NEAR THE
OHIO VALLEY AS THE LOW RIDES UP THE BOUNDARY...BUT SOME OF THE
RAIN FROM THIS SYSTEM MAY REACH INTO SOUTHEAST ILLINOIS. IN
ADDITION...A SHORTWAVE CURRENTLY OVER KANSAS/OKLAHOMA WILL SWING
ACROSS ILLINOIS THIS AFTERNOON. GFS AND CANADIAN MODELS DEVELOP
SOME LIGHT QPF FROM MISSOURI NORTHEAST INTO CENTRAL ILLINOIS
PRIMARILY THIS AFTERNOON...ALTHOUGH SOUNDINGS OFF THE RAP MODEL
SHOW QUITE A BIT OF DRY AIR ABOVE THE PERSISTENT INVERSION AROUND
900 MB. HIGHEST POPS TODAY WILL MAINLY BE SOUTH OF I-72...BUT WILL
CARRY SOME SLIGHTS NORTHWEST OF THE ILLINOIS RIVER. ANOTHER
SHORTWAVE WILL TRACK INTO THE WESTERN GREAT LAKES ON TUESDAY...BUT
IT STILL APPEARS ANY ASSOCIATED PRECIP WITH THIS FEATURE WILL
REMAIN TO OUR NORTH.
LONG TERM...WEDNESDAY THROUGH SUNDAY...
A STRONG UPPER WAVE COMING ONTO THE PACIFIC COAST ON TUESDAY IS
STILL ON TRACK TO HELP DEVELOP A MAJOR STORM SYSTEM ACROSS THE
CENTRAL PLAINS ON WEDNESDAY. STILL A FAIR AMOUNT OF SPREAD AMONG
THE EVENING MODELS ON TIMING AND PLACEMENT OF THE CENTRAL
LOW. EACH MODEL SHOWING SOME CONSISTENCY WITH ITS PREVIOUS
RUN...BUT NOT AMONGST EACH OTHER...WITH THE NAM THE FURTHEST
NORTHWEST AND THE ECMWF THE FURTHEST SOUTH. THIS IS GOING TO BE
CRITICAL IN DETERMINING THE EXACT PLACEMENT OF HEAVY SNOW ACROSS
PORTIONS OF THE MIDWEST. GIVEN THAT THE PARENT WAVE HAS NOT BEEN
ADEQUATELY SAMPLED BY THE UPPER AIR NETWORK YET...THESE
INCONSISTENCIES ARE NOT UNUSUAL.
THIS FORECAST PACKAGE WILL GO WITH A GFS/ECMWF BLEND...WITH THE
LOW ROUGHLY PARALLELING THE ILLINOIS RIVER LATE WEDNESDAY NIGHT
AND EARLY THURSDAY. RAIN IS EXPECTED TO OVERSPREAD THE AREA
WEDNESDAY EVENING...WITH SOME POTENTIAL FOR THUNDER IN THE
SOUTHEAST CWA LATE WEDNESDAY NIGHT IN THE WARM SECTOR. THE COLD
AIR WILL RAPIDLY POUR IN BEHIND THE LOW ON THURSDAY MORNING...WITH
FORECAST SOUNDINGS SHOWING A FAIRLY CLEAN AND RAPID TRANSITION
FROM RAIN TO SNOW GOING FROM WEST TO EAST ACROSS THE CWA. HEAVIEST
SNOWFALL IN THE DEFORMATION ZONE WOULD BE MORE ACROSS EASTERN IOWA
INTO SOUTHERN WISCONSIN...BUT AN INCH OR TWO OF SNOW IS POSSIBLE
NORTH OF A BLOOMINGTON TO CANTON LINE. ACCUMULATIONS MAY BE
HAMPERED BY THE UNSEASONABLY WARM GROUND...BUT A HEAVY FALLING
SNOW MAY BE ENOUGH TO OVERCOME THAT. WHAT SNOW DOES FALL WILL BLOW
AROUND QUITE A BIT...AS ALL MODELS SHOW VERY WINDY CONDITIONS
DEVELOPING THURSDAY AS THE LOW PULLS AWAY. BUFKIT SOUNDINGS OFF
THE GFS SHOW SURFACE GUSTS AROUND 45 MPH THURSDAY AFTERNOON AND
EARLY EVENING. ANY LINGERING SNOW SHOULD TAPER OFF THURSDAY
EVENING.
THE REMAINDER OF THE FORECAST PERIOD IS EXPECTED TO BE QUIET...
WITH TEMPERATURES RUNNING BELOW NORMAL.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1043 AM CST MON DEC 17 2012
.DISCUSSION...
ISSUED 1040 AM CST MON DEC 17 2012
UPDATING THE FORECAST TO INCREASE RAIN CHANCES TODAY SE OF THE IL RIVER
WITH LIKELY POPS AND ALSO COOLING THE HIGHS A BIT WITH LOW CLOUDS
LINGERING ALL DAY. SLEET MAY BE MIXED IN WITH THE RAIN LATE THIS
MORNING NORTH OF I-72. JUST HAD A REPORT OF SLEET WITH THE RAIN AT
MOUNT PULASKI IN SE LOGAN COUNTY AROUND 1030 AM. HIGHS MOSTLY IN
THE LOW TO MID 40S THIS AFTERNOON...RANGING FROM THE UPPER 30S TO
NEAR 40F OVER THE IL RIVER VALLEY IN THE NW TO THE UPPER 40S AND
LOWER 50S NEAR THE WABASH RIVER. THUNDERSTORM CURRENTLY JUST EAST
OF LAWRENCE COUNTY AND LIFTING NE ACROSS SW INDIANA. SPC HAS THUNDERSTORM
CHANCES SE OF I-70 TODAY WHILE SLIGHT RISK OF SEVERE STORM IS OVER
CENTRAL/WESTERN KY...MID TN AND FAR SE INDIANA.
1004 MB LOW PRESSURE ALONG THE KY/IL BORDER BETWEEN EVANSVILLE AND
PADUCAH TO LIFT NE INTO SOUTHERN OH BY THIS EVENING. MEANWHILE A
SHORT WAVE NEAR KC TO MOVE ACROSS SOUTHERN IL THIS EVENING. THIS
TO KEEP A GOOD CHANCE OF RAIN SHOWERS TODAY SE OF THE IL RIVER AND
LINGERING IN EASTERN/SE IL THIS EVENING. NNE WINDS LESS THAN 10
MPH TO TURN NW LATER THIS AFTERNOON AND EVENING.
07
&&
.AVIATION...
ISSUED 520 AM CST MON DEC 17 2012
MVFR CONDTIONS...WITH LOCAL IFR CIGS...ARE EXPECTED TO CONTINUE
THIS FORECAST PERIOD. WEAK WEATHER SYSTEM WILL MOVE ACROSS THE
AREA TODAY WHICH MAY BRING SOME LIGHT RAIN TO PARTS OF THE
FORECAST AREA BUT COVERAGE STILL APPEARS TO BE TOO LIMITED TO
INCLUDE IN TAFS OTHER THAN VCSH. FORECAST SOUNDINGS AND TIME
HEIGHT CROSS SECTIONS CONTINUE TO SHOW THE MOISTURE TRAPPED
BELOW A RATHER STRONG LOW LEVEL INVERSION WHICH WILL BE VERY
SLOW TO BREAK OVER THE NEXT 12 TO 18 HOURS. MODELS CONTINUE TO
SUGGEST IN THE WAKE OF THE WEATHER SYSTEM THAT MOVES THRU THE
AREA TODAY...SOME BREAK UP OF THE MOISTURE MAY OCCUR IN THE LOW
LEVELS BUT WILL BE A BIT MORE CONSERVATIVE THAN WHAT MODELS WERE
INDICATING FOR THIS AFTN. WILL BRING CIGS UP TO VFR IN MOST
LOCATIONS...EXCEPT CMI...AFTER 00Z. SURFACE WINDS WILL REMAIN
LIGHT TODAY...MOSTLY OUT OF A NORTHERLY DIRECTION.
SMITH
&&
.PREV DISCUSSION...
ISSUED 230 AM CST MON DEC 17 2012
PRIMARY FOCUS FOR THIS FORECAST INVOLVES THE MAJOR STORM SYSTEM
THAT WILL BE CROSSING THE MIDWEST WEDNESDAY NIGHT AND THURSDAY...
INCLUDING PRECIPITATION TYPES AND STRONG WINDS. RAIN POTENTIAL
LATER TODAY IS A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH TUESDAY...
MAIN FOCUS FOR ANY RAIN TODAY IS WITH A SURFACE LOW CURRENTLY OVER
SOUTH CENTRAL MISSOURI...WITH A FRONTAL BOUNDARY ARCING NORTHEAST
ALONG THE OHIO RIVER. BEST PRECIPITATION CHANCES WILL BE NEAR THE
OHIO VALLEY AS THE LOW RIDES UP THE BOUNDARY...BUT SOME OF THE
RAIN FROM THIS SYSTEM MAY REACH INTO SOUTHEAST ILLINOIS. IN
ADDITION...A SHORTWAVE CURRENTLY OVER KANSAS/OKLAHOMA WILL SWING
ACROSS ILLINOIS THIS AFTERNOON. GFS AND CANADIAN MODELS DEVELOP
SOME LIGHT QPF FROM MISSOURI NORTHEAST INTO CENTRAL ILLINOIS
PRIMARILY THIS AFTERNOON...ALTHOUGH SOUNDINGS OFF THE RAP MODEL
SHOW QUITE A BIT OF DRY AIR ABOVE THE PERSISTENT INVERSION AROUND
900 MB. HIGHEST POPS TODAY WILL MAINLY BE SOUTH OF I-72...BUT WILL
CARRY SOME SLIGHTS NORTHWEST OF THE ILLINOIS RIVER. ANOTHER
SHORTWAVE WILL TRACK INTO THE WESTERN GREAT LAKES ON TUESDAY...BUT
IT STILL APPEARS ANY ASSOCIATED PRECIP WITH THIS FEATURE WILL
REMAIN TO OUR NORTH.
LONG TERM...WEDNESDAY THROUGH SUNDAY...
A STRONG UPPER WAVE COMING ONTO THE PACIFIC COAST ON TUESDAY IS
STILL ON TRACK TO HELP DEVELOP A MAJOR STORM SYSTEM ACROSS THE
CENTRAL PLAINS ON WEDNESDAY. STILL A FAIR AMOUNT OF SPREAD AMONG
THE EVENING MODELS ON TIMING AND PLACEMENT OF THE CENTRAL
LOW. EACH MODEL SHOWING SOME CONSISTENCY WITH ITS PREVIOUS
RUN...BUT NOT AMONGST EACH OTHER...WITH THE NAM THE FURTHEST
NORTHWEST AND THE ECMWF THE FURTHEST SOUTH. THIS IS GOING TO BE
CRITICAL IN DETERMINING THE EXACT PLACEMENT OF HEAVY SNOW ACROSS
PORTIONS OF THE MIDWEST. GIVEN THAT THE PARENT WAVE HAS NOT BEEN
ADEQUATELY SAMPLED BY THE UPPER AIR NETWORK YET...THESE
INCONSISTENCIES ARE NOT UNUSUAL.
THIS FORECAST PACKAGE WILL GO WITH A GFS/ECMWF BLEND...WITH THE
LOW ROUGHLY PARALLELING THE ILLINOIS RIVER LATE WEDNESDAY NIGHT
AND EARLY THURSDAY. RAIN IS EXPECTED TO OVERSPREAD THE AREA
WEDNESDAY EVENING...WITH SOME POTENTIAL FOR THUNDER IN THE
SOUTHEAST CWA LATE WEDNESDAY NIGHT IN THE WARM SECTOR. THE COLD
AIR WILL RAPIDLY POUR IN BEHIND THE LOW ON THURSDAY MORNING...WITH
FORECAST SOUNDINGS SHOWING A FAIRLY CLEAN AND RAPID TRANSITION
FROM RAIN TO SNOW GOING FROM WEST TO EAST ACROSS THE CWA. HEAVIEST
SNOWFALL IN THE DEFORMATION ZONE WOULD BE MORE ACROSS EASTERN IOWA
INTO SOUTHERN WISCONSIN...BUT AN INCH OR TWO OF SNOW IS POSSIBLE
NORTH OF A BLOOMINGTON TO CANTON LINE. ACCUMULATIONS MAY BE
HAMPERED BY THE UNSEASONABLY WARM GROUND...BUT A HEAVY FALLING
SNOW MAY BE ENOUGH TO OVERCOME THAT. WHAT SNOW DOES FALL WILL BLOW
AROUND QUITE A BIT...AS ALL MODELS SHOW VERY WINDY CONDITIONS
DEVELOPING THURSDAY AS THE LOW PULLS AWAY. BUFKIT SOUNDINGS OFF
THE GFS SHOW SURFACE GUSTS AROUND 45 MPH THURSDAY AFTERNOON AND
EARLY EVENING. ANY LINGERING SNOW SHOULD TAPER OFF THURSDAY
EVENING.
THE REMAINDER OF THE FORECAST PERIOD IS EXPECTED TO BE QUIET...
WITH TEMPERATURES RUNNING BELOW NORMAL.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
528 AM CST MON DEC 17 2012
.DISCUSSION...
ISSUED 230 AM CST MON DEC 17 2012
PRIMARY FOCUS FOR THIS FORECAST INVOLVES THE MAJOR STORM SYSTEM
THAT WILL BE CROSSING THE MIDWEST WEDNESDAY NIGHT AND THURSDAY...
INCLUDING PRECIPITATION TYPES AND STRONG WINDS. RAIN POTENTIAL
LATER TODAY IS A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH TUESDAY...
MAIN FOCUS FOR ANY RAIN TODAY IS WITH A SURFACE LOW CURRENTLY OVER
SOUTH CENTRAL MISSOURI...WITH A FRONTAL BOUNDARY ARCING NORTHEAST
ALONG THE OHIO RIVER. BEST PRECIPITATION CHANCES WILL BE NEAR THE
OHIO VALLEY AS THE LOW RIDES UP THE BOUNDARY...BUT SOME OF THE
RAIN FROM THIS SYSTEM MAY REACH INTO SOUTHEAST ILLINOIS. IN
ADDITION...A SHORTWAVE CURRENTLY OVER KANSAS/OKLAHOMA WILL SWING
ACROSS ILLINOIS THIS AFTERNOON. GFS AND CANADIAN MODELS DEVELOP
SOME LIGHT QPF FROM MISSOURI NORTHEAST INTO CENTRAL ILLINOIS
PRIMARILY THIS AFTERNOON...ALTHOUGH SOUNDINGS OFF THE RAP MODEL
SHOW QUITE A BIT OF DRY AIR ABOVE THE PERSISTENT INVERSION AROUND
900 MB. HIGHEST POPS TODAY WILL MAINLY BE SOUTH OF I-72...BUT WILL
CARRY SOME SLIGHTS NORTHWEST OF THE ILLINOIS RIVER. ANOTHER
SHORTWAVE WILL TRACK INTO THE WESTERN GREAT LAKES ON TUESDAY...BUT
IT STILL APPEARS ANY ASSOCIATED PRECIP WITH THIS FEATURE WILL
REMAIN TO OUR NORTH.
LONG TERM...WEDNESDAY THROUGH SUNDAY...
A STRONG UPPER WAVE COMING ONTO THE PACIFIC COAST ON TUESDAY IS
STILL ON TRACK TO HELP DEVELOP A MAJOR STORM SYSTEM ACROSS THE
CENTRAL PLAINS ON WEDNESDAY. STILL A FAIR AMOUNT OF SPREAD AMONG
THE EVENING MODELS ON TIMING AND PLACEMENT OF THE CENTRAL
LOW. EACH MODEL SHOWING SOME CONSISTENCY WITH ITS PREVIOUS
RUN...BUT NOT AMONGST EACH OTHER...WITH THE NAM THE FURTHEST
NORTHWEST AND THE ECMWF THE FURTHEST SOUTH. THIS IS GOING TO BE
CRITICAL IN DETERMINING THE EXACT PLACEMENT OF HEAVY SNOW ACROSS
PORTIONS OF THE MIDWEST. GIVEN THAT THE PARENT WAVE HAS NOT BEEN
ADEQUATELY SAMPLED BY THE UPPER AIR NETWORK YET...THESE
INCONSISTENCIES ARE NOT UNUSUAL.
THIS FORECAST PACKAGE WILL GO WITH A GFS/ECMWF BLEND...WITH THE
LOW ROUGHLY PARALLELING THE ILLINOIS RIVER LATE WEDNESDAY NIGHT
AND EARLY THURSDAY. RAIN IS EXPECTED TO OVERSPREAD THE AREA
WEDNESDAY EVENING...WITH SOME POTENTIAL FOR THUNDER IN THE
SOUTHEAST CWA LATE WEDNESDAY NIGHT IN THE WARM SECTOR. THE COLD
AIR WILL RAPIDLY POUR IN BEHIND THE LOW ON THURSDAY MORNING...WITH
FORECAST SOUNDINGS SHOWING A FAIRLY CLEAN AND RAPID TRANSITION
FROM RAIN TO SNOW GOING FROM WEST TO EAST ACROSS THE CWA. HEAVIEST
SNOWFALL IN THE DEFORMATION ZONE WOULD BE MORE ACROSS EASTERN IOWA
INTO SOUTHERN WISCONSIN...BUT AN INCH OR TWO OF SNOW IS POSSIBLE
NORTH OF A BLOOMINGTON TO CANTON LINE. ACCUMULATIONS MAY BE
HAMPERED BY THE UNSEASONABLY WARM GROUND...BUT A HEAVY FALLING
SNOW MAY BE ENOUGH TO OVERCOME THAT. WHAT SNOW DOES FALL WILL BLOW
AROUND QUITE A BIT...AS ALL MODELS SHOW VERY WINDY CONDITIONS
DEVELOPING THURSDAY AS THE LOW PULLS AWAY. BUFKIT SOUNDINGS OFF
THE GFS SHOW SURFACE GUSTS AROUND 45 MPH THURSDAY AFTERNOON AND
EARLY EVENING. ANY LINGERING SNOW SHOULD TAPER OFF THURSDAY
EVENING.
THE REMAINDER OF THE FORECAST PERIOD IS EXPECTED TO BE QUIET...
WITH TEMPERATURES RUNNING BELOW NORMAL.
GEELHART
&&
.AVIATION...
ISSUED 520 AM CST MON DEC 17 2012
MVFR CONDTIONS...WITH LOCAL IFR CIGS...ARE EXPECTED TO CONTINUE
THIS FORECAST PERIOD. WEAK WEATHER SYSTEM WILL MOVE ACROSS THE
AREA TODAY WHICH MAY BRING SOME LIGHT RAIN TO PARTS OF THE
FORECAST AREA BUT COVERAGE STILL APPEARS TO BE TOO LIMITED TO
INCLUDE IN TAFS OTHER THAN VCSH. FORECAST SOUNDINGS AND TIME
HEIGHT CROSS SECTIONS CONTINUE TO SHOW THE MOISTURE TRAPPED
BELOW A RATHER STRONG LOW LEVEL INVERSION WHICH WILL BE VERY
SLOW TO BREAK OVER THE NEXT 12 TO 18 HOURS. MODELS CONTINUE TO
SUGGEST IN THE WAKE OF THE WEATHER SYSTEM THAT MOVES THRU THE
AREA TODAY...SOME BREAK UP OF THE MOISTURE MAY OCCUR IN THE LOW
LEVELS BUT WILL BE A BIT MORE CONSERVATIVE THAN WHAT MODELS WERE
INDICATING FOR THIS AFTN. WILL BRING CIGS UP TO VFR IN MOST
LOCATIONS...EXCEPT CMI...AFTER 00Z. SURFACE WINDS WILL REMAIN
LIGHT TODAY...MOSTLY OUT OF A NORTHERLY DIRECTION.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
230 AM CST MON DEC 17 2012
.DISCUSSION...
ISSUED 230 AM CST MON DEC 17 2012
PRIMARY FOCUS FOR THIS FORECAST INVOLVES THE MAJOR STORM SYSTEM
THAT WILL BE CROSSING THE MIDWEST WEDNESDAY NIGHT AND THURSDAY...
INCLUDING PRECIPITATION TYPES AND STRONG WINDS. RAIN POTENTIAL
LATER TODAY IS A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH TUESDAY...
MAIN FOCUS FOR ANY RAIN TODAY IS WITH A SURFACE LOW CURRENTLY OVER
SOUTH CENTRAL MISSOURI...WITH A FRONTAL BOUNDARY ARCING NORTHEAST
ALONG THE OHIO RIVER. BEST PRECIPITATION CHANCES WILL BE NEAR THE
OHIO VALLEY AS THE LOW RIDES UP THE BOUNDARY...BUT SOME OF THE
RAIN FROM THIS SYSTEM MAY REACH INTO SOUTHEAST ILLINOIS. IN
ADDITION...A SHORTWAVE CURRENTLY OVER KANSAS/OKLAHOMA WILL SWING
ACROSS ILLINOIS THIS AFTERNOON. GFS AND CANADIAN MODELS DEVELOP
SOME LIGHT QPF FROM MISSOURI NORTHEAST INTO CENTRAL ILLINOIS
PRIMARILY THIS AFTERNOON...ALTHOUGH SOUNDINGS OFF THE RAP MODEL
SHOW QUITE A BIT OF DRY AIR ABOVE THE PERSISTENT INVERSION AROUND
900 MB. HIGHEST POPS TODAY WILL MAINLY BE SOUTH OF I-72...BUT WILL
CARRY SOME SLIGHTS NORTHWEST OF THE ILLINOIS RIVER. ANOTHER
SHORTWAVE WILL TRACK INTO THE WESTERN GREAT LAKES ON TUESDAY...BUT
IT STILL APPEARS ANY ASSOCIATED PRECIP WITH THIS FEATURE WILL
REMAIN TO OUR NORTH.
LONG TERM...WEDNESDAY THROUGH SUNDAY...
A STRONG UPPER WAVE COMING ONTO THE PACIFIC COAST ON TUESDAY IS
STILL ON TRACK TO HELP DEVELOP A MAJOR STORM SYSTEM ACROSS THE
CENTRAL PLAINS ON WEDNESDAY. STILL A FAIR AMOUNT OF SPREAD AMONG
THE EVENING MODELS ON TIMING AND PLACEMENT OF THE CENTRAL
LOW. EACH MODEL SHOWING SOME CONSISTENCY WITH ITS PREVIOUS
RUN...BUT NOT AMONGST EACH OTHER...WITH THE NAM THE FURTHEST
NORTHWEST AND THE ECMWF THE FURTHEST SOUTH. THIS IS GOING TO BE
CRITICAL IN DETERMINING THE EXACT PLACEMENT OF HEAVY SNOW ACROSS
PORTIONS OF THE MIDWEST. GIVEN THAT THE PARENT WAVE HAS NOT BEEN
ADEQUATELY SAMPLED BY THE UPPER AIR NETWORK YET...THESE
INCONSISTENCIES ARE NOT UNUSUAL.
THIS FORECAST PACKAGE WILL GO WITH A GFS/ECMWF BLEND...WITH THE
LOW ROUGHLY PARALLELING THE ILLINOIS RIVER LATE WEDNESDAY NIGHT
AND EARLY THURSDAY. RAIN IS EXPECTED TO OVERSPREAD THE AREA
WEDNESDAY EVENING...WITH SOME POTENTIAL FOR THUNDER IN THE
SOUTHEAST CWA LATE WEDNESDAY NIGHT IN THE WARM SECTOR. THE COLD
AIR WILL RAPIDLY POUR IN BEHIND THE LOW ON THURSDAY MORNING...WITH
FORECAST SOUNDINGS SHOWING A FAIRLY CLEAN AND RAPID TRANSITION
FROM RAIN TO SNOW GOING FROM WEST TO EAST ACROSS THE CWA. HEAVIEST
SNOWFALL IN THE DEFORMATION ZONE WOULD BE MORE ACROSS EASTERN IOWA
INTO SOUTHERN WISCONSIN...BUT AN INCH OR TWO OF SNOW IS POSSIBLE
NORTH OF A BLOOMINGTON TO CANTON LINE. ACCUMULATIONS MAY BE
HAMPERED BY THE UNSEASONABLY WARM GROUND...BUT A HEAVY FALLING
SNOW MAY BE ENOUGH TO OVERCOME THAT. WHAT SNOW DOES FALL WILL BLOW
AROUND QUITE A BIT...AS ALL MODELS SHOW VERY WINDY CONDITIONS
DEVELOPING THURSDAY AS THE LOW PULLS AWAY. BUFKIT SOUNDINGS OFF
THE GFS SHOW SURFACE GUSTS AROUND 45 MPH THURSDAY AFTERNOON AND
EARLY EVENING. ANY LINGERING SNOW SHOULD TAPER OFF THURSDAY
EVENING.
THE REMAINDER OF THE FORECAST PERIOD IS EXPECTED TO BE QUIET...
WITH TEMPERATURES RUNNING BELOW NORMAL.
GEELHART
&&
.AVIATION...
ISSUED 1145 PM CST SUN DEC 16 2012
PERSISTENT LOW LEVEL CLOUDS AND MVFR CONDITIONS WILL BE THE RULE
MUCH OF THE TAF PERIOD OVERNIGHT AND THROUGH THE DAY ON MONDAY.
THERE SHOULD BE A BRIEF TIME PRIOR TO OR AROUND DAYBREAK WHEN IFR
CIGS ARE ANTICIPATED. A FEW TAF SITES ARE ALREADY WITHIN 100-300
FT OF IFR CEILINGS...SO CONFIDENCE IS FAIRLY HIGH THIS WILL OCCUR.
INCREASING HIGH AND MID LEVEL CLOUDINESS DURING THE EARLY MORNING WILL
KEEP THE LOW CLOUDS AND MVFR CIGS IN PLACE THROUGH THE MORNING AND
MUCH OF THE AFTERNOON. PARTS OF CENTRAL IL SOUTHEAST OF A KSPI-
KCMI LINE WILL BE ON THE NORTHERN FRINGES OF SOME LIGHT RAIN AS A
RESULT OF A SHORTWAVE MOVING INTO THE OHIO VALLEY. HAVE INTRODUCED
VCSH INTO THE TAF DURING THE AFTERNOON AS A RESULT.
A SHIFT OF THE MAIN UPPER LEVEL SHORTWAVE TROF AXIS TO OUR EAST
DURING THE LATE AFTERNOON AND EVENING MONDAY WILL RESULT IN
SUBSIDENCE...SOMEWHAT DRIER AIR...AND AN EVENTUAL END TO THE MVFR
CONDITIONS.
MILLER
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
330 PM CST MON DEC 17 2012
.SYNOPSIS...
LIGHT WINDS AND LINGERING LOW LEVEL MOISTURE HAS KEPT LOW CLOUDS AND
LIGHT FOG IN PLACE TODAY ACROSS THE FORECAST AREA. AS A RESULT...
TEMPERATURES HAVE STRUGGLED TO CLIMB...HAVING ONLY REACHED THE UPPER
20S NORTH TO MID 30S SOUTH THIS AFTERNOON. MSAS ANALYSIS INDICATED A
RIDGE OF HIGH PRESSURE REACHED FROM TX TO MN...FLANKED BY LOW
PRESSURE MOVING ALONG A COLD FRONT IN NORTHERN KY TO THE SE...AND A
LEE TROUGH REACHING FROM NORTHERN MT TO EASTERN CO. IN THE UPPER
LEVELS...A TROUGH AXIS REACHED FROM THE EASTERN DAKOTAS TO THE MO
BOOTHEEL REGION. UPSTREAM...12Z ANALYSIS INDICATED A 160 KT JET AT
300 MT MOVING IN THE STRONG...NEARLY ZONAL FLOW...ACROSS NORTHERN CA
INTO THE GREAT BASIN REGION. AN UPPER LOW WAS OFF THE NORTHERN BC
COAST WITH A TROUGH AXIS EXTENDING S-SW INTO THE PACIFIC.
&&
.SHORT TERM...TONIGHT AND TUESDAY...
DEVELOPING ACTIVE PATTERN WILL SEND ANOTHER ROUND OF PRECIPITATION
THROUGH THE REGION TONIGHT INTO EARLY TUESDAY. FORECAST CHALLENGES
CENTER ON THIS PRECIPITATION LATE TONIGHT INTO TUESDAY...ALONG WITH
LOW CLOUDS AND FOG.
LATEST VISIBLE SATELLITE IMAGES SHOW AN AREA OF CLOUDS OVER NORTH
CENTRAL MO INTO SOUTHERN IA...SLOWLY MIGRATING EASTWARD WITH THE
UPPER LEVEL TROUGH. AS THIS EXTENDS EASTWARD INTO THE SOUTHERN THIRD
OF THE FORECAST AREA AROUND SUNSET...THERE WILL BE A POTENTIAL FOR
THICKENING OF THE FOG THAT HAS LINGERED OVER SE IA AND ADJACENT
AREAS OF MO AND IL THIS EVENING. BASED ON LATEST RAP LOW LEVEL
MOISTURE FIELDS...STRATUS WILL LIKELY REMAIN IN PLACE THROUGH THE
NIGHT OVER THE REMAINDER OF THE FORECAST AREA...AND LIKELY FILL BACK
IN ANY HOLES THAT DEVELOP ACROSS THE SOUTH. WILL GO WITH PATCHY FOG
WORDING FOR NOW AND MONITOR THE SOUTH THIS EVENING FOR POSSIBLE
UPDATES TO MORE DENSE OR WIDESPREAD COVERAGE. A STRIKE AGAINST FOG
TONIGHT WILL BE THE INCOMING SUBSIDENCE BEHIND THE UPPER LEVEL WAVE
AND INCREASING WINDS TOWARD MORNING AS A SURFACE LOW APPROACHES.
AS SEEN TODAY...CLOUDS...LINGERING MOISTURE AND WEAK WINDS WILL
LIMIT DIURNAL TEMPERATURE CURVES AND HAVE KEPT MINS CLOSE TO CURRENT
DEWPOINTS...FROM THE MID 20S NORTH TO LOWER 30S SOUTH.
THE FOCUS THEN TURNS TO AN IMPULSE IN THE FAST ZONAL FLOW ALOFT THAT
WAS MOVING ACROSS CENTRAL ID AT MIDDAY. MODELS DEVELOP THIS INTO A
CLIPPER LIKE LOW PRESSURE SYSTEM AS THE ENERGY MOVES OVER THE LEE
TROUGH TONIGHT. THIS FAST MOVING LOW DEVELOPS OVER NEB LATE
TONIGHT...THEN HEADS EASTWARD OVER THE FORECAST AREA DURING THE
DAY TUESDAY. HAVE GENERALLY FOLLOWED A BLEND OF THE GFS/ECMWF AND
GEM WITH THIS FEATURE...WHICH DEVELOPS A NW TO SE ORIENTED WARM
ADVECTION WING OF LIGHT SNOW OVER THE CENTRAL PART OF THE FORECAST
AREA BETWEEN 06Z AND 12Z AND HAVE KEPT CHANCE POPS THERE. THE
POTENTIAL FOR LIGHT SNOW OR FLURRIES SHOULD THEN SHIFT TO THE FAR
NORTH AND NORTHEAST BY AFTERNOON AS THE LOW MOVES TOWARD CHICAGO.
WITH LIMITED MOISTURE AND RAPID PROGRESSION...SNOWFALL AMOUNTS
SHOULD BE WELL BELOW AN INCH IN MOST LOCATIONS WITH THE BEST CHANCES
OF A LIGHT COATING NORTH OF THE HIGHWAY 30 CORRIDOR. HAVE TRENDED
SOME PARTIAL CLEARING FROM SW TO NE IN THE AFTERNOON...BUT THIS MAY
END UP BEING TOO OPTIMISTIC DUE TO THE LINGERING MOISTURE AND
CYCLONIC FLOW THROUGH THE AFTERNOON. BRISK WESTERLY WINDS IN THE FAR
SOUTH MAY ALLOW TEMPERATURES TO REACH THE UPPER 40S...WHILE HIGHS IN
THE NORTH ARE KEPT IN THE UPPER 30S.
SHEETS
.LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
ALL LONG TERM FCST ENERGY INTO HANDLING MIDWEEK STORM SYSTEM...WITH
THE WEEKEND LOOKING IN BETWEEN SYSTEMS AND RATHER BENIGN/SEASONABLE
ANYWAY THROUGH EARLY MONDAY. ASSESSING THE LATEST 12Z MEDIUM RANGE
MODEL RUNS AS WELL AS THE NAM...SURPRISINGLY GOOD AGREEMENT WITH
GENERAL SFC LOW AND MID LEVEL LOW PATHS BUT WITH SOME TRACKING
SPEED AND STRENGTH VARIANCES. THIS TAKING INTO ACCOUNT BULK OF WAVE
ENERGY THAT WILL DRIVE THE STORM STILL OFF THE PACIFIC NORTHWEST
COAST AND SOUTH OF THE GULF OF AK. ALL MODELS BUT THE 12Z ECMWF THAT
IS. WHILE THE OTHERS HAVE TRENDED FURTHER NORTH AND WEST WITH THEIR
LATEST 12Z RUNS WHICH MAKE FOR MORE OF A PRECIP TYPE/AMOUNT CHALLENGE
FOR THE DVN CWA...THE CONSISTENT ECMWF WOULD STILL IMPACT MOST OF THE
LOCAL FCST AREA WITH A QUICKER SWITCH OVER TO SNOW AND MORE AREAS
STARTING OFF AS SNOW TO BEGIN WITH. THE ENSEMBLE SFC LOW TRACK OF
THE 12Z GFS/NAM/UKMET/GEM ALL HOOK THE DEVELOPING LOW FROM THE OK
PANHANDLE ON WED UP THROUGH NORTHEAST MO/WEST CENTRAL IL LATE WED
NIGHT...TO A NORTH CENTRAL IL POSITION BY THU MORNING...AND THEN
BOMB IT OUT ACRS LOWER MI INTO THU EVENING. THE 12Z EURO MAINTAINS
A TRACK FURTHER TO THE SOUTHEAST OF THE ENSEMBLE PATH...SOUTHWEST MO
TO NEAR THE STL AREA BY THU MORNING AND THEN OFF TO WEST CENTRAL
INDIANA BY EARLY THU AFTERNOON. THE ENSEMBLE OF SOLUTIONS BESIDES THE
ECMWF WOULD GENERALLY SUGGEST MUCH OF THE SOUTHEAST HALF TO TWO
THIRDS OF THE FCST AREA TO BE RAIN OR EVEN EXPERIENCE SOME
CONVECTION THROUGH MIDNIGHT WED NIGHT...WHILE THE NORTHWEST THIRD
MIXES AND DYNAMICALLY COOLS INTO WET ACCUMULATING SNOW AFTER 03Z
THU. AS DEF ZONE CONTINUES TO FORM AND LLVL COLD CONVEYOR IN-WRAPS
AND INCREASES...THESE MODELS GENERALLY SUGGEST THE SWITCH OVER TO
WET SNOW TO CONTINUE FROM WEST-NORTHWEST TO THE EAST AFTER MIDNIGHT
AND INTO EARLY THU MORNING ACRS THE DVN CWA. 3-7 INCHES POSSIBLE BY
12Z THU ALONG AND WEST OF A LINE FROM SIGOURNEY IA...TO EAST OF
CEDAR RAPIDS AND TO WEST OF DBQ. SOME ADDITIONAL ACCUMS OF 1-2
INCHES IN THESE AREAS POSSIBLE THROUGH 18Z THU...BUT BULK OF
ACCUMULATING SNOW TO SWITCH EASTWARD ACRS THE REST OF THE CWA WITH 3-
6 INCHES POSSIBLE ALONG AND NORTH OF A LINE FROM MT PLEASANT IA...TO
THE QUAD CITIES..AND TO STERLING IL.
WHILE THE NORTHWEST THIRD AND NORTH CENTRAL PORTIONS OF THE DVN CWA
MAY EVENTUALLY GET 4-8+ INCHES BY THU EVENING...THE ENSEMBLES MINUS
THE ECMWF SUGGEST THE HIGHEST SNOWFALL TOTALS OF 8-12+ INCHES OCCUR
WEST AND NORTH OF THE DVN CWA ACRS SOUTH CENTRAL IA...UP THROUGH
NORTHEASTERN IA INTO SW/CENTRAL WI. EXTENT OF BOMBING CYCLONE TO THE
EAST STILL INDICATED BY BULK OF THE MODEL RUNS TO DRIVE VERY STRONG
NORTH BECOMING NORTHWEST WINDS LATE WED NIGHT AND ESPECIALLY ON
THU...SUSTAINED 25 TO 35 MPH WITH GUSTS TO AT LEAST 45 MPH. GRAVITY
WAVE PHENOMENA WEST OF RAPIDLY DEEPENING CYCLONE COULD ALSO PRODUCE
ISOLATED GUSTS OVER 50 MPH AT MAX DEEPENING STAGE ON THU. THUS WHERE
ACCUMULATING SNOWS OCCUR...NEAR BLIZZARD OR BLIZZARD CONDITIONS VERY
POSSIBLE. BACK TO THE ECMWF...IT/S TRACK WOULD MEAN MORE OF A DIRECT
HIT UPON THE LOCAL AREA AND HIGHER SNOW AMOUNTS FURTHER EAST AND
SOUTH...ESPECIALLY TAKING INTO ACCOUNT SOME FUJI-WARA EFFECT OF
SECONDARY VORT INTERACTING IN TROF BASE AND ENHANCING DEF ZONE SNOWS
ACRS THE LOCAL AREA ON THU. DESPITE ONGOING MODEL UNCERTAINTY AND
THE SYSTEM TO BE BETTER SAMPLED FOR THE 00Z RUNS TONIGHT AND
ESPECIALLY 12Z TUE...WILL ISSUE A WINTER STORM WATCH FOR ROUGHLY THE
NORTHWEST HALF OF THE DVN CWA FOR WED NIGHT AND THU GIVING A NOD
SOMEWHAT TO THE ENSEMBLE TRACK. THE STRONG WINDS LOOK TO BE A LARGE
IMPACT EVEN FOR ADVISORY LEVEL OR SLIGHTLY LESS SNOW AMOUNTS. DO FEEL
THE CWA WILL HAVE TO EVENTUALLY BE DIVIDED INTO WINTER STORM WARNING
AND ADVISORY AREAS...BUT WHERE AN WHEN STILL UP IN THE AIR. A
WATCHFUL EYE WILL ALSO NEED TO BE OPEN FOR TRENDS ON THE NEXT 1-2
MODEL RUNS BACK CLOSER TO THE CONSISTENT ECMWF...WHICH WOULD THEN
WARRANT THE NEED OF EXPANDING THE WATCH SOUTH AND EAST. ..12..
&&
.AVIATION...
STRATUS AND FOG WILL LIKELY REMAIN IN PLACE TONIGHT...WITH LATEST
TRENDS NOW SUGGESTING LIGHT SNOW OR FLURRIES MAY IMPACT CID...DBQ
AND POSSIBLY MLI TOWARD DAWN TUESDAY. LINGERING LOW LEVEL MOISTURE
AND LIGHT WINDS WILL CONTINUE IFR AND POSSIBLE LIFR CONDITIONS DUE
TO LOW CIGS AND FOG THROUGH THE NIGHT. A FAST MOVING LOW PRESSURE
SYSTEM MOVING OUT OF THE ROCKIES WILL SPREAD LIGHT SNOW OR FLURRIES
ACROSS EASTERN IA AND NW IL LATE TONIGHT AND INTO TUESDAY MORNING.
CONFIDENCE IS INCREASING THAT THIS PRECIPITATION MAY AFFECT AT LEAST
THE DBQ TERMINAL...AND THIS WILL LIKELY BE REFLECTED IN UPDATES THIS
EVENING. OTHERWISE...CURRENT FORECASTS HAVE CONDITIONS IMPROVING TO
MVFR AFTER SUNRISE TUESDAY. SHEETS
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR BENTON-BUCHANAN-CEDAR-CLINTON-DELAWARE-
DUBUQUE-HENRY IA-IOWA-JACKSON-JEFFERSON-JOHNSON-JONES-
KEOKUK-LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR JO DAVIESS-ROCK ISLAND.
MO...NONE.
&&
$$
SHEETS/12
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1140 PM CST SUN DEC 16 2012
.UPDATE...
HAVE UPDATED THE FORECAST TO REMOVE PRECIPITATION WORDING AS MUCH OF
THE LIGHT RAIN/SNOW HAS DISSIPATED ACROSS CENTRAL IOWA. ALSO HAVE
INCREASED AREA OF PATCHY FOG MENTION TO INCLUDE NORTHWESTERN CWA
THIS EVENING...AND UPGRADED ALL FOG MENTION LATE TONIGHT TO AREAS OF
FOG VERSUS THE PATCHY IN THE PREVIOUS GRIDS. BUFKIT SOUNDINGS
SHOWING DECENT SATURATION NEAR THE SURFACE LATE TONIGHT WITH LOW
STRATUS ACROSS NORTHWESTERN IOWA/SRN MN STILL EXPECTED TO CONTINUE
PROGRESSING SOUTH SOUTHEASTWARD OVERNIGHT. AREAS BENEATH THE LOWER
CLOUDS ALREADY DROPPING INTO THE 1/2 MILE TO 2 MILE RANGE...SO
EXPECT AREAS ESPECIALLY ACROSS NORTHERN IOWA TO DROP OFF LATE
TONIGHT AS TEMPERATURES CONTINUE TO COOL OFF A BIT MORE AND
DEWPOINTS REMAIN IN THE MID TO UPPER TEENS.
.SHORT TERM /TONIGHT/...
CHALLENGING FORECAST ESPECIALLY FROM A FOG AND LOW CLOUDS
PERSPECTIVE. FOG AND LOW CLOUDS HAVE BEEN STUBBORN IN LIFTING TODAY
ESPECIALLY ACROSS THE SOUTHERN...CENTRAL AND EASTERN CWA. AND IN THE
NORTHWESTERN CWA WHERE THE FOG AND LOW CLOUDS DID LIFT...ANOTHER
AREA OF LOW CLOUDS HAS BEEN MOVING SOUTHEAST FROM SOUTH DAKOTA AND
MINNESOTA.
HAVE TAKEN A SOMEWHAT PESSIMISTIC APPROACH TO THE LOW CLOUDS AND FOG
FOR TONIGHT. ALTHOUGH BUFKIT NAM SOUNDINGS ARE OPTIMISTIC...THE
BUFKIT RAP SOUNDINGS ARE QUITE PESSIMISTIC. THE FORECAST TENDS TO
SPLIT THE DIFFERENCE WITH A LEAN TOWARD THE LOW CLOUDS AND FOG BEING
STUBBORN. LOW LEVEL MOISTURE IS EXPECTED TO REMAIN PLENTIFUL
OVERNIGHT ESPECIALLY IN THOSE AREAS THAT STILL HAVE LOW CLOUDS AND
FOG. WITH WIND SPEEDS DECREASING OVERNIGHT...MIXING WILL DIMINISH
AND THE FOG IS EXPECTED TO COME BACK. THUS HAVE GONE WITH PATCHY FOG
WORDING IN MANY AREAS FOR TONIGHT/S FCST GRIDS. IN THE NORTHWESTERN
CWA...HAVE BROUGHT THE CLOUDS BACK IN ALONG WITH THE POSSIBILITY OF
PATCHY FOG THERE AS WELL. THE LOWEST VISIBILITIES IN THE FOG ARE
EXPECTED TO BE IN THE NORTHEASTERN CWA.
ON A DIFFERENT NOTE...SOME WEAK FRONTOGENETICAL FORCING HAS LED TO
AN AREA OF ECHOES ON THE RADAR MAINLY ACROSS THE WESTERN CWA TODAY.
OVER TIME THE ECHOES HAVE SPREAD EASTWARD...INDICATING THAT THE
FORCING IS TRANSLATING EASTWARD...WHICH IS SUPPORTED BY MODEL CROSS
SECTIONS. SINCE THE PRECIP IS NOT EXPECTED TO REACH THE GROUND
MUCH...IF AT ALL...HAVE GONE ONLY WITH SLIGHT CHANCE POPS ACROSS THE
SOUTHERN CWA INTO THIS EVE. THERE IS A DRY ENOUGH LAYER BETWEEN THE
LAYER OF FORCING AND THE LOWER LEVEL MOISTURE THAT THE PRECIP IS NOT
EXPECTED TO MAKE IT THROUGH THAT DRIER LAYER.
.LONG TERM /MONDAY THROUGH SUNDAY/...
A PAIR OF SUCCESSIVE 500 MB SHORTWAVES WILL MOVE ACROSS NORTHERN
IOWA...THE FIRST ON MONDAY AND THE SECOND ON TUESDAY MORNING. AT THE
SURFACE A HIGH PRESSURE RIDGE WILL CROSS THE AREA ON MONDAY...WITH
THE MID-LEVEL SHORTWAVE GENERATING CLOUDS BUT FORECAST SOUNDINGS
INDICATING TOO MUCH DRY AIR IN THE LOWER LEVELS TO RESULT IN
PRECIPITATION. ON MONDAY NIGHT HOWEVER THE RIDGE WILL MOVE OFF TO
THE EAST...AND A SURFACE LOW WILL DEVELOP AROUND THE BLACK HILLS
AHEAD OF THE APPROACHING SECOND WAVE AND MOVE QUICKLY EASTWARD
TOWARD IOWA. THIS WILL CAUSE SURFACE WINDS TO COME AROUND QUICKLY TO
SOUTH BY EARLY TUESDAY MORNING WITH AN INCREASE IN ATMOSPHERIC
MOISTURE. AS THE WAVE AND LOW CROSS THE AREA ON TUESDAY MORNING IT
WILL PROVIDE A BRIEF OPPORTUNITY FOR SOME LIGHT SNOW ACROSS OUR FAR
NORTH BEFORE THE SYSTEM CLEARS OUT RAPIDLY TO THE EAST. AT THIS TIME
WILL STICK WITH JUST SLIGHT POPS ROUGHLY NORTH OF HIGHWAY 20 ON
TUESDAY MORNING...AND LITTLE IF ANY ACCUMULATION IS ANTICIPATED.
THE BIGGEST POTENTIAL WEATHER IMPACT OF THE SEVEN DAY FORECAST WILL
COME FROM A LONGWAVE 500 MB TROUGH COMING ASHORE OVER THE PACIFIC
U.S. COAST LATE ON TUESDAY. IT STILL APPEARS THAT THIS TROUGH WILL
NOT BE FULLY PHASED...AND THAT MOST OF THE ENERGY WILL DIG INTO THE
SOUTHERN STREAM WITH A NORTHERN STREAM WAVE TRAILING SLIGHTLY
BEHIND. AS THE OVERALL SYSTEM MOVES EASTWARD TOWARD THE CENTRAL U.S.
AND IOWA THE COMPLICATED EVOLUTION OF THE TWO INTERTWINED WAVES WILL
HAVE DRAMATIC IMPACTS ON THE DETAILS OF THEIR ASSOCIATED SENSIBLE
WEATHER. THE SOUTHERN STREAM WAVE WILL GENERATE A STRONG SURFACE LOW
PRESSURE CENTER OVER THE SOUTHERN HIGH PLAINS ON TUESDAY NIGHT/EARLY
WEDNESDAY...WHICH WILL SUBSEQUENTLY MOVE EAST NORTHEAST ACROSS
MISSOURI AND ILLINOIS...WITH A LARGE SWATH OF SNOW SPREADING ALONG
THE NORTHWESTERN FLANK OF THE TRACK. HOWEVER THE PHASING
ISSUES...COMBINED WITH THE FACT THAT THE ENTIRE SYSTEM IS STILL WELL
OFFSHORE AND NOT BEING SAMPLED BY THE UPPER AIR NETWORK...ARE
WREAKING HAVOC WITH THE FORECAST OF THE STORM TRACK BEING OUTPUT BY
THE VARIOUS PROGNOSTIC MODELS. A SHIFT OF 50 OR 100 MILES ONE WAY OR
ANOTHER WILL MAKE THE DIFFERENCE BETWEEN THE HEAVIER SNOW SWATH
FALLING ACROSS CENTRAL IOWA...SOUTHEASTERN IOWA...OR NORTHEASTERN
MISSOURI. GIVEN THE INHERENT UNCERTAINTY IN THIS SCENARIO AND POOR
CONSISTENCY AMONG THE MODELS HAVE OPTED TO KEEP THE FORECAST VERY
CLOSE TO PREVIOUS ISSUANCES...WITH LIKELY TO CATEGORICAL POPS ACROSS
ABOUT THE SOUTHEASTERN HALF OR TWO THIRDS OF THE CWA. IT IS STILL
TOO EARLY TO MAKE ANY FORECAST OF SNOWFALL AMOUNTS...BUT SEVERAL
INCHES OF SNOWFALL ARE LIKELY TO THE NORTHWEST OF THE LOW AND
PROBABLY SOMEWHERE IN THE SOUTHEASTERN HALF OF OUR AREA. THIS WILL
BE CLOSELY MONITORED OVER THE NEXT SEVERAL DAYS.
THE MIDWEEK SYSTEM WILL CLEAR OUT QUICKLY LATE THURSDAY AND THURSDAY
NIGHT...AFTER WHICH QUIET AND DRY WEST NORTHWESTERLY 500 MB FLOW
WILL BE ESTABLISHED. THIS WILL LEAD TO COOLER WEATHER...ESPECIALLY
IF A SNOW PACK IS IN PLACE AFTER THE WEDNESDAY/THURSDAY STORM...WITH
NO ADDITIONAL PRECIPITATION IN THE FORECAST.
&&
.AVIATION...17/06Z
LIFR/IFR STRATUS HAS MOVED INTO THE NORTHERN TAF SITES AND IS
EXPECTED TO CONTINUE TO PROGRESS SOUTH TO SOUTHEASTWARD IN AREAS
ALONG AND NORTHEAST OF THE SFC HIGH AXIS. VSBYS EXPECTED TO CONTINUE
TO LOWER THROUGH THE NIGHT AS WELL BENEATH THE HIGH...WITH
POSSIBILITY OF LIFR/IFR VSBYS AS WELL. GREATEST CHANCES WILL BE AT
KMCW AND KFOD. WINDS WILL SHIFT AROUND TO THE NORTHEAST TO EAST
THROUGH MONDAY MORNING...AND THEN AROUND TO THE SOUTH TO SOUTHEAST
BY LATE MONDAY AFTERNOON INTO MONDAY EVENING AS THE SFC HIGH AXIS
MOVES THROUGH THE CWA. ONCE WINDS GO SOUTH...EXPECT CIGS TO SCOUR
OUT SOME WITH POSSIBLY MVFR/LOW VFR CIGS EXPECTED.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...ZOGG
LONG TERM...LEE
AVIATION...BEERENDS
UPDATE...BEERENDS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1014 AM CST MON DEC 17 2012
.UPDATE...
ISSUED AT 1014 AM CST MON DEC 17 2012
UPDATED THE PUBLIC GRIDS TO REFLECT LATEST OBSERVATIONAL AND
GUIDANCE TRENDS. SOLID LOW OVERCAST CONDITIONS EXIST ALONG AND
NORTH OF A SURFACE BOUNDARY RUNNING FROM NEAR KPOF TO NEAR KEHR.
LATEST LAMP GUIDANCE IS QUITE PESSIMISTIC...KEEPING OVERCAST
CONDITIONS WELL INTO THIS EVENING. THE LATEST RUC AND NAM PUSH THE
BOUNDARY EASTWARD THROUGH THE AREA THIS AFTERNOON. THE LOW CLOUDS
SHOULD PUSH IN BEHIND THE BOUNDARY. THIS SHOULD LEAD TO LITTLE
WARMING BEHIND THE BOUNDARIES CURRENT LOCATION...AND SOME COOLING
THIS AFTERNOON ONCE THE FRONT MOVES THROUGH A GIVEN LOCATION. USED
RUC DATA TO ACHIEVE THESE ADJUSTMENTS.
AHEAD OF THE BOUNDARY...MAINLY OVER WEST KENTUCKY STRATOCU WILL
ALLOW SOME MODEST WARMING. HOWEVER...SIGNIFICANT DESTABILIZATION
WILL HAVE A HARD TIME DEVELOPING. FEEL THAT SHOWERS WILL
INCREASE/SPREAD EAST NORTHEAST ACROSS WEST KENTUCKY THROUGH EARLY
AFTERNOON...AND SOME THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE
LATER THIS AFTERNOON...AS IT MOVES OUT OF OUR FORECAST AREA. WILL
HAVE TO MONITOR CLOSELY THIS AFTERNOON...BUT WOULD BE SURPRISED TO
SEE ANYTHING MORE THAN AN ISOLATED HAIL OR WIND REPORT.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 340 AM CST MON DEC 17 2012
SHOWERS CONTINUE TO DEVELOP ACROSS WEST KENTUCKY EARLY THIS
MORNING. MODELS ARE INDICATING LI`S ANYWHERE FROM -1 TO -5...AND
CAPE VALUES OF 300 TO 1000 J/KG ACROSS EXTREME SOUTHEAST
MISSOURI...WEST KENTUCKY...AND SOUTHWEST INDIANA TODAY...MAINLY
DURING THE MORNING HOURS. MODELS SHOW MINIMAL QPF ACROSS OUR
REGION TODAY...SO SLIGHT TO LOW CHANCE POPS RIGHT NOW LOOK
REASONABLE ACROSS THE AFOREMENTIONED REGIONS. SPC HAS THE EASTERN
THIRD OF THE PAH FORECAST AREA IN A SLIGHT RISK TODAY WHERE MODELS
ARE SHOWING THE BEST INSTABILITY. ACTIVITY SHOULD BEGIN TAPERING
OFF THIS AFTERNOON...AND ANY LINGERING PRECIP SHOULD MOVE OUT OF
THE REGION BY MID EVENING AT THE LATEST.
WINDS SWITCH TO THE NORTHWEST LATE TODAY AND INTO TONIGHT...WHICH
WILL BRIEFLY BRING IN COOLER AIR TO THE AREA. BY TUESDAY...WITH
SOME SUNSHINE AND A QUICK RETURN OF SOUTHERLY WINDS...TEMPERATURES
WILL CLIMB BACK INTO THE MIDDLE TO UPPER 50S. HIGH PRESSURE WILL
CONTINUE TO BUILD OVER THE SOUTHEAST U.S. FOR THE EARLY PART OF
THE WORK WEEK...KEEPING US DRY AND EXTREMELY MILD INTO WEDNESDAY.
CLOUDS WILL INCREASE WEDNESDAY AHEAD OF THE APPROACHING STRONG
COLD FRONT. ECMWF HINTS AT SOME PRECIP MAKING INTO OUR FAR
WEST COUNTIES BY LATE WEDNESDAY...SO KEPT A SLIGHT CHANCE OF
SHOWERS WEDNESDAY AFTERNOON FOR THE OZARK FOOTHILLS OF MISSOURI.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 340 AM CST MON DEC 17 2012
VIGOROUS H5 WAVE IS FORECAST TO BE OVER THE FOUR CORNERS REGION
MIDDAY WEDNESDAY...AND RAPIDLY MOVE EAST INTO THE CENTRAL PLAINS BY
MIDNIGHT WEDNESDAY NIGHT. BY MIDDAY THURSDAY THE STRENGTHENING
WAVE SHOULD BE OVER CENTRAL ILLINOIS. SURFACE LOW PRESSURE IS
FORECAST TO TRACK NORTHEAST FROM NCNTRL OKLAHOMA WEDNESDAY EVENING
TO JUST NORTH OF ST. LOUIS THURSDAY MORNING TO SOUTH CENTRAL
MICHIGAN BY THURSDAY EVENING. THIS LOW TRACK IS BASED ON A CONSENSUS
TRACK SIMILAR TO YESTERDAY...AND CLOSE TO THE 12Z UKMET...ALL OF
WHICH IS A COMPROMISE TO THE FASTER/SLIGHTLY FARTHER NORTH TRACK
OF THE 00Z GFS VS. THE SLOWER FARTHER SOUTH 12Z/00Z ECMWF RUNS.
WENT INTO THE LOW END OF CATEGORICAL FOR POPS WEDNESDAY NIGHT.
TEMPS SHOULD REMAIN STEADY NEARLY ALL NIGHT GIVEN WELL ESTABLISHED
WARM SECTOR OVER THE AREA. PROSPECT FOR SEVERE WEATHER STILL HIGHLY
CONDITIONAL...MAINLY WITH RESPECT TO INSTABILITY. CANNOT RULE IT
OUT GIVEN THE STRENGTH AND DYNAMIC NATURE OF THE SYSTEM...RESULTANT
WIND FIELDS. BUT STILL REMAINS TO BE SEEN HOW MUCH OF A FAVORABLE
AIR MASS AND RESPECTABLE INSTABILITY WILL BE IN PLAY.
POPS SHOULD END FAIRLY QUICKLY FROM SW TO NE AS THE SYSTEM QUICKLY
DEPARTS THURSDAY. ABANDONED DIURNAL ASPECT AS STRONG WNW WINDS
AND CAA WILL ALLOW TEMPS AND DEW POINTS TO DROP SHARPLY THROUGH THE
DAY...ESPECIALLY THE MORNING HOURS IN THE WAKE OF THE FRONT.
LINGERED ONLY A SLIGHT CHANCE RW-/SW- UP ALONG THE I-64 CORRIDOR
THURSDAY AFTERNOON GIVEN THE QUICK SYSTEM DEPARTURE AND BETTER
MOISTURE TO OUR NORTH.
QUIET WEATHER FOR THE REMAINDER OF THE LONG TERM FORECAST...AS THE
MODELS DEVELOP A MUNDANE QUASI ZONAL FLOW PATTERN OVER MUCH OF
THE CONUS...SOME SLIGHT AMPLIFICATION TOWARD THE END OF THE
PERIOD. TEMPERATURES WILL BE CLOSE TO NORMAL THROUGH THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 541 AM CST MON DEC 17 2012
IFR TO LIFR CIGS AND MVFR TO IFR VSBYS EXPECTED THROUGH
18Z...THOUGH BOTH COULD BE HIGHLY VARIABLE. SHOWER CHANCES NOT
HIGH ENOUGH TO INCLUDE IN TAFS. OVERALL CONDITIONS SHOULD
IMPROVE BY A CATEGORY THIS AFTERNOON. LIGHT WINDS THIS MORNING
WILL BECOME WEST THEN NORTHWEST AT 6 TO 11 KTS THIS AFTERNOON AND
EVENING. VFR CONDITIONS WILL RETURN BETWEEN 05Z AND 10Z.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...DRS
SHORT TERM...RST
LONG TERM....CN
AVIATION...RST
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1241 PM EST MON DEC 17 2012
.SYNOPSIS...
ISSUED AT 315 AM EST MON DEC 17 2012
LOW PRESSURE OVER EASTERN LAKE SUPERIOR WILL WEAKEN AND MOVE TOWARD
JAMES BAY TODAY. CHANCES FOR RAIN AND SNOW WILL CONTINUE TO DECREASE
THROUGH TONIGHT AS THIS OCCURS. A WEAK LOW PRESSURE SYSTEM PASSING
TO OUR SOUTH MAY BRING LIGHT RAIN AND SNOW TUESDAY AFTERNOON INTO
TUESDAY NIGHT. A MUCH STRONGER SYSTEM WILL MOVE INTO THE REGION
THURSDAY...WITH WINTER STORM CONDITIONS EXPECTED IN AT LEAST SOME
PARTS OF THE GREAT LAKES REGION.
&&
.UPDATE...
ISSUED AT 1237 PM EST MON DEC 17 2012
LIGHT LAKE EFFECT SNOW AND RAIN SHOWERS CONTINUE ACROSS THE
FAVORED AREAS OF EASTERN UPPER AND NORTHWEST LOWER MICHIGAN AS
WEAKISH CAA CONTINUES. STILL EXPECT COVERAGE TO TAPER OFF RATHER
QUICKLY THROUGH THE AFTERNOON OVER NORTHWEST LOWER AS OFF THE DECK
DRYING FURTHER DEEPENS. LIGHT SNOW SHOWERS EXPECTED INTO THE EARLY
EVENING NEAR WHITEFISH BAY OVER EASTERN UPPER WITH MINIMAL
ACCUMULATIONS.
UPDATE ISSUED AT 1009 AM EST MON DEC 17 2012
BROAD TROUGHINESS REMAINS OVER THE GREAT LAKES...WITH ONE RATHER
COMPACT EMBEDDED VORT LOBE EXITING EASTERN UPPER MICHIGAN. LOW LEVEL
MOISTURE REMAINS ABUNDANT...AS EVIDENT BY WIDESPREAD STRATUS AND 12Z
LOCAL SOUNDING WHICH HAD A MOISTURE-RICH PROFILE UP THROUGH H80.
TOP-DOWN DRYING ALREADY EVIDENT JUST UPSTREAM...WITH KGRB SOUNDING
SHOWING RAPID DEPLETION OF MOISTURE ABOVE H85 CENTERED INVERSION.
THIS DRYING WILL CONTINUE TO SPREAD EAST...WITH A RAPID FALL-OFF OF
MID LEVEL MOISTURE INTO THIS AFTERNOON...ESPECIALLY ACROSS NORTHERN
LOWER MICHIGAN. COMBINE THIS WITH JUST MARGINALLY UNSTABLE LOW LEVEL
PROFILES OVER LAKE MICHIGAN (HIGH RES RAP ANALYSIS SHOWED -6C H85
AIR OVER THE BIG POND)...AND ONGOING LIGHT LAKE EFFECT SNOW/RAIN
SHOWERS SHOULD TAPER OFF THROUGH EARLY AFTERNOON. MOISTURE REMAINS
SOMEWHAT DEEPER OVER LAKE SUPERIOR...SUGGESTING LIGHT RAIN/SNOW
SHOWERS CONTINUING THROUGH MUCH OF THIS AFTERNOON...PERHAPS BRINGING
SOME VERY MINOR SNOW ACCUMULATIONS (SUB ONE INCH) OVER THE FAVORED
SNOWBELTS. TEMPERATURES LOOK TO REMAIN PRETTY STEADY-STATE IN THE
MID AND UPPER 30S AS DIURNAL INFLUENCES ARE COUNTERED BY WEAKISH LOW
LEVEL CAA. ABOVE WELL HANDLED BY INHERITED FORECAST WITH ONLY
COSMETIC CHANGES NEEDED TO ACCOUNT FOR REAL-TIME RADAR TRENDS.
UPDATE ISSUED AT 700 AM EST MON DEC 17 2012
SOME FINE-TUNING...PUSHING MORNING POPS A LITTLE FURTHER SOUTH
INTO THE HTL/CAD AREAS...AND KEEPING PRECIP MIXED A FEW MORE HOURS
IN EASTERN UPPER BEFORE GOING ALL SNOW. NEWLY ARRIVING STAFF
MEMBERS REPORT SEEING A FEW WET FLAKES MIXING IN ON THE
COMMUTE...SO HAVE ADDED IN A MIX A BIT SOONER OVER THE HIGH
TERRAIN IN THE GLR AREA.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 315 AM EST MON DEC 17 2012
RATHER NEBULOUS FORECAST AS WE WELCOME THE NEW WORK WEEK...WITH MAIN
ISSUES BEING CLOUD COVER/TEMPS AND SMALL CHANCES FOR MAINLY NUISANCE
LAKE SNOW SHOWERS/FLURRIES. EARLY MORNING ANALYSIS PLACES WEAK
SURFACE LOW OVER THE EASTERN TIP OF LAKE SUPERIOR...WITH ITS
ASSOCIATED WEAK OCCLUDED FRONTAL BOUNDARY SLOWLY WORKING THROUGH
NORTHERN LOWER. JUST A SUBTLE WIND SHIFT WITH THIS FEATURE...BUT
WITH A SLIGHTLY COOLER AIR MASS GRADUALLY FILTERING INTO THE CWA
(STILL NOT VERY COLD FOR MID DECEMBER). REGIONAL RADAR MOSAIC SHOWS
EARLIER LAST BATCH OF SHOWERS EXITING THE AREA...AS WEAK SECONDARY
UPPER VORT IS TRACKING OVERHEAD...WHILE SATELLITE PICS/OBS SHOW
QUITE THE EXPANSIVE LOW STRATUS CLOUD DECK WELL ENTRENCHED ALL
THROUGHOUT THE GREAT LAKES/UPPER MIDWEST.
FOR TODAY...BROAD UPPER TROUGHING WILL CONTINUE TO DOMINATE THE
GREAT LAKES REGION...AS STRONGER SOUTHERN STREAM ENERGY LIFTS
THROUGH THE TENNESSEE VALLEY. AIRMASS THROUGH THE DAY WILL BECOME
INCREASINGLY COOL ALOFT (H8 TEMPS AROUND -6C BY MIDDAY) WHILE ALSO
DRYING OUT ACROSS NORTHERN LOWER. EASTERN UPPER WILL BE A DIFFERENT
STORY AS APPROACH OF YET ANOTHER WEAK SHORTWAVE BRINGS A BRIEF ROUND
OF DEEPER MOISTURE ACROSS EASTERN LAKE SUPERIOR. THAT SETUP IN
COMBINATION WITH MARGINAL LAKE INSTABILITY SHOULD GIVEN AT LEAST
DECENT COVERAGE OF MAINLY LIGHT LAKE SNOW SHOWERS THROUGH THE DAY
ACROSS NORTHERN CHIPPEWA COUNTY IN A MEAN WEST/NORTHWEST FLOW
REGIME. ACCUMULATIONS SHOULD BE HINDERED BY SURFACE TEMPS AT OR
SLIGHTLY ABOVE FREEZING...BUT PERHAPS UP TO AN INCH COULD FALL.
NORTHERN LOWER LOOKS MUCH MORE PALTRY AS MOISTURE IS VERY THIN AND
OVERLAKE INSTABILITY IS EVEN WORSE (DELTA T VALUES UP AROUND 12C).
THAT SETUP SHOULD GIVE US PLENTY OF LAKE STRATUS...AND MAYBE A FEW
LIGHT SNOW SHOWERS...BUT PROBABLY MORE LIKE JUST SOME FLURRIES...
WITH THOSE LIKELY TO END THROUGH THE AFTERNOON AS MOISTURE FURTHER
THINS TO BELOW 900MB. HIGHS DEFINITELY A BIT CLOSER TO NORMAL BUT
STILL ABOVE...WITH READINGS MAINLY IN THE 32-38F RANGE.
TONIGHT LOOKS EVEN MORE QUIET AS THE WEAK SURFACE LOW PROGRESSES
TOWARD JAMES BAY...WHILE STRONGER LOW PRESSURE SLIDES THROUGH THE
OHIO VALLEY. THIS WILL ALLOW LOW LEVEL RIDGING TO BUILD INTO
NORTHERN MICHIGAN THROUGH THE NIGHT. WEAKENING GRADIENT SHOULD ALLOW
FOR SOME LAND BREEZE DEVELOPMENT...THEORETICALLY HELPING PUSH SOME
OF THE LAKE STRATUS CLOSER TO THE COASTS. HOWEVER...DEGREE OF
CLEARING REMAINS TO BE SEEN...AND NOT OVERLY ENTHUSIASTIC GIVEN SUCH
WIDESPREAD STRATUS SPREAD WELL UPSTREAM THROUGH THE NORTHERN
PLAINS/UPPER MIDWEST. DON`T FORESEE MUCH IN THE WAY OF ANY LINGERING
LAKE SNOW SHOWERS AS MOISTURE IS EVEN MORE THIN...BUT SUPPOSE A
ROGUE FLURRY IS POSSIBLE. OVERNIGHT LOWS WILL BE TIED TO DEGREE OF
CLEARING...BUT GIVEN OUR RECENT HISTORY AND STRONGER LIKELIHOOD FOR
CLOUDS TO PREVAIL...FEEL WARMER IS PROBABLY BETTER...AND WILL SIDE
WITH READINGS MAINLY IN THE UPPER HALF OF THE 20S TO LOWER 30S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 315 AM EST MON DEC 17 2012
MILD AND RELATIVELY UNEVENTFUL WX WILL HOLD INTO WEDNESDAY. A
VARIETY OF OPTIONS ARE POSSIBLE AFTER THAT...THOUGH /UNEVENTFUL/
DOES NOT APPEAR TO BE ONE OF THEM. A WEAK N-S ORIENTED RIDGE AXIS
WILL BE OVER LOWER MI EARLY TUESDAY...TEMPORARILY DISLODGED BY A
VERY WEAK SURFACE WAVE TRANSITING FAR SOUTHERN LOWER MI IN THE
EVENING. SMALL PRECIP CHANCES MAY BE IN THE OFFING TUE-WED...BUT THE
MAIN SHOW WILL CLEARLY OCCUR AFTER THAT.
TUESDAY...850MB THERMAL TROF WILL BE DISPLACED EAST ACROSS LAKE
HURON DURING THE DAY...ALLOWING FOR A 2-3C RECOVERY TO -4 TO -7C.
THE STRONGEST WARM ADVECTION/ISENTROPIC ASCENT WILL FOCUS JUST TO
OUR SW...MOVING TOWARD SOUTHERN LAKE MI IN THE AFTERNOON. THIS IS IN
ADVANCE OF A 1004MB LOW MOVING EAST FROM CENTRAL IOWA TO NORTHERN
IL. FGEN FORCING WILL CONTRIBUTE TO A BAND OF MOISTENING ALOFT THAT
EVENTUALLY REACHES NE WI...CENTRAL AND SOUTHERN LOWER MI LATE. DRIER
AIR BELOW 800MB WILL BE MORE STUBBORN TO DISLODGE...BUT MODEL
SOUNDINGS ARE MORE OPTIMISTIC IN PROGGING PRECIP DOWN TO THE SURFACE
BY LATE AFTERNOON/EARLY EVENING. SO EARLIER ADDITION OF CHANCE POPS
TO PARTS OF NW LOWER MI STILL LOOKS VERY REASONABLE. WILL REMOVE A
MENTION OF MIX OVER THE HIGHER TERRAIN (CAD AREA)...WHERE SNOW
SHOULD PREVAIL IF PRECIP DEVELOPS. CLOSER TO LAKE MI (MBL/FKS)...A
RA/SN MENTION IS GOOD. PLENTY OF CLOUDS FOR MOST...COULD BE SOME
THIN SPOTS EARLY IN NE LOWER BEFORE MID/HIGH CLOUDS THICKEN. MAX
TEMPS IN THE 30S.
TUE NIGHT/WEDNESDAY...WARM ADVECTION/FGEN BAND OF MID-LEVEL MOISTURE
WILL CONTINUE TO LIFT ACROSS THE FORECAST AREA TUE NIGHT.
HOWEVER...LIFT WILL WEAKEN WITH TIME...ESPECIALLY OVERNIGHT...AS THE
WEAK SURFACE LOW REACHES LAKE ERIE AND FILLS. SMALL CHANCE POPS ARE
STILL REASONABLE FOR MUCH OF NORTHERN LOWER MI TUE EVENING (STILL
HOLDING ONTO A MIX IN COASTAL AREAS)...BUT SLIGHT CHANCE OR LESS
WILL SUFFICE BY THE TIME THE BAND LIFTS ACROSS EASTERN UPPER/FAR NE
LOWER MI OVERNIGHT. STRATUS SHOULD BE CONSIDERABLE BEHIND THE
DEPARTING BAND...BUT THERE MAY SOME BREAKS IN THE FAR SE. HIGH
PRESSURE MAKES A BRIEF RETURN WED MORNING...THEN SHUNTS EAST AS LOW
PRESSURE DEEPENS IN OK. PRECIP MAY START TO BREAK OUT IN
IOWA/NORTHERN IL DURING THE DAY...BUT NOT THIS FAR NE. IF WE GET
LUCKY...WE COULD SEE SOME BRIEF PERIODS OF SUN AS LOW LEVEL MOISTURE
GETS INCREASINGLY THIN...BUT MID/HIGH CLOUD WILL BE ON THE INCREASE
LATE.
MIN TEMPS ABOVE GUIDANCE GIVEN ABUNDANT CLOUDS...MID 20S TO LOWER
30S. MAX TEMPS MID 30S TO NEAR 40F.
REST OF THE FORECAST...YESTERDAYS TIGHTLY-CLUSTERED SOLUTIONS WERE
DESTINED NOT TO REPEAT. THE DAY SHIFT NOTED A TREND TOWARD A LESS
AMPLIFIED AND MORE SOUTHERLY TRACK FOR THE LOW FORECAST TO CROSS THE
LAKES REGION LATE THURSDAY. TONIGHT...WE/VE MOVED BACK TO A MEAN
THAT LOOKS SIMILAR TO LAST NIGHT...THOUGH WITH MORE IN THE WAY OF
MODEL SPREAD. THEY (AND I) CONTINUE TO STRUGGLE A BIT WITH COMPETING
ELEMENTS. WE HAVE A TON OF ENERGY POURING INTO THE PAC COAST TO PUSH
THINGS ALONG...AND A WEAK BLOCKING RIDGE OVER FAR EASTERN CANADA.
THE BLOCK IS NOT IMPRESSIVE AND WILL BE DISLODGED...BUT HOW QUICKLY?
THE INCOMING UPPER TROF TAKES ON A NEGATIVE TILT...BUT OVERALL THE
PATTERN IS QUITE PROGRESSIVE AND NOT HIGHLY AMPLIFIED. HOW MUCH WILL
THE SYSTEM WRAP UP...SLOW DOWN...AND GET TUGGED NW (IF AT ALL)?
THE NAM AND DGEX REPRESENT DEEPER AND MORE NORTHERLY TRACKS THAT
WOULD BE MORE RAIN AND LESS SNOW FOR US. 00Z ECMWF OFFERS THE MOST
SOUTHERLY...SNOWIEST SOLUTION. GFS/GEM ARE SOMEWHERE IN BETWEEN...
THOUGH WITH THE GEM SLOWER THAN THE REST OF THE MODELS. SOME SORT OF
GEM/GFS/ECMWF MISH-MASH IS MOST APPROPRIATE...AS WE STILL HAVE TIME
TO SEE HOW THE DETAILS FALL OUT.
PRECIP SHOULD ARRIVE IN SW SECTIONS OVERNIGHT WED NIGHT...MAINLY AS
SNOW. A TRACK ACROSS CENTRAL LOWER MI LATE THURSDAY WILL OPEN UP AT
LEAST THE SE HALF OF THE FORECAST AREA TO MIX WITH/TURN TO RAIN.
WINDY/SNOWY CONDITIONS LATE THURSDAY NIGHT INTO FRIDAY AS SYSTEM
DEPARTS. POTENTIAL FOR SUBSTANTIAL LAKE ENHANCEMENT...BUT VERY
DIFFICULT TO ANSWER THE FETCH QUESTION YET GIVEN MODEL DIFFS. WILL
TRY TO ADD A FEW DETAILS TO THE HAZ WX OUTLOOK. COLDER TEMPS (NEAR
CLIMO) OVER THE WEEKEND...WITH DECREASING CHANCES FOR LAKE EFFECT AS
SURFACE RIDGING TRIES TO EDGE EAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1237 PM EST MON DEC 17 2012
PERSISTENT MVFR/LOW END VFR OVERCAST EXPECTED TO CONTINUE THROUGH
THE TAF CYCLE AS ABUNDANT LOW LEVEL MOISTURE REMAINS LOCKED IN PLACE.
SOME LIGHT RAIN SHOWERS EXPECTED VC KTVC AND KPLN FOR A FEW MORE
HOURS BEFORE THEY DISSIPATE. LIGHT WINDS WILL ALSO CONTINUE
THROUGH THE DURATION.
&&
.MARINE...
ISSUED AT 315 AM EST MON DEC 17 2012
LIGHT WINDS AND LOW WAVES ARE EXPECTED AS WE HEAD INTO THE MID WEEK
PERIOD...AS WEAK LOW PRESSURE DRIFTS OUT OF THE REGION TODAY...ONLY
TO BE REPLACED BY HIGH PRESSURE THROUGH AT LEAST WEDNESDAY EVENING.
THE ONE EXCEPTION WILL BE TODAY...AS SLIGHTLY STRONGER WINDS WILL BE
FOUND ACROSS THE WATERS (STILL LESS THAN 20 KNOTS) AS COOLER AIR
FILTERS INTO THE REGION. AFTER THAT...STRONG LOW PRESSURE IS
EXPECTED TO TRACK THROUGH THE REGION WEDNESDAY NIGHT THROUGH
FRIDAY...USHERING IN A PERIOD OF MUCH STRONGER WINDS...WITH GALE
FORCE GUSTS VERY POSSIBLE. WIDESPREAD RAIN AND/OR SNOW IS ALSO
EXPECTED TO ACCOMPANY THIS SYSTEM...WITH LAKE EFFECT SNOW SHOWERS
AND CONTINUED GUSTY CONDITIONS LIKELY FOR THE WEEKEND.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MB
SYNOPSIS...JZ
SHORT TERM...LAWRENCE
LONG TERM...JZ
AVIATION...MB
MARINE...LAWRENCE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1237 PM EST MON DEC 17 2012
.UPDATE...
ISSUED AT 1120 AM EST MON DEC 17 2012
SHORTWAVE THAT BROUGHT LGT SNOW/FLURRIES TO NORTHERN CWA EARLIER
THIS MORNING IS SLIDING OVR FAR EASTERN LK SUPERIOR NEAR WHITEFISH
POINT/SAULT STE MARIE. FEATURE PRETTY IMPRESSIVE LOOKING ON WV WITH
TIGHT SPIN NOTED. CANADIAN RADAR/SFC OBS SHOWING WIDESPREAD LGT
PRECIP FM ERY TO ANJ. VSBY AT ERY NOW DOWN TO 4SM...INDICATING SNOW
IS INTENSIFYING SOME. COULD SEE ADDITIONAL SNOW ACCUMS UP TO 1 INCH
THROUGH EARLY AFTN...BUT WOULD BE PRETTY LOCALIZED OVR NORTHERN LUCE
COUNTY. SEEMS LIKE RAIN/SNOW MIX SEEN AT CYAM/ANJ THIS MORNING IS
STAYING JUST TO NORTH OF ERY TOWARD WHITEFISH POINT. ELSEWHERE JUST A
FEW FLURRIES/SNOW SHOWERS ARE ONGOING OVR NCNTRL CWA AND MAYBE KEWEENAW
TOO...THOUGH CMX HAS NOT REPORTED ANYTHING IN A WHILE. GOING POPS
WERE IN FINE SHAPE...LITTLE CHANGES MADE THERE. LINGERING LGT SNOW
SHOULD BE EXITING THE EASTERN CWA THIS EVENING.
BASED ON 12Z SOUNDING FM GRB SHOWING MOISTURE UP TO 875MB TRAPPED
BENEATH INCREASING SUBSIDENCE INVERSION...LOW SUN ANGLE IN MID
DECEMBER AND LACK OF DRY AIR ADVECTION INTO REGION...HAVE KEPT SKIES
CLOUDY THROUGH THE DAY AND EVEN INTO TONIGHT. RAP ONLY MODEL THAT
HAD GOOD HANDLE ON DEPTH OF MOISTURE. NAM SOUNDING AT GRB FOR 12Z
SHOWED THIN LAYER OF MOISTURE AT 950MB WITH DRYING ABOVE...WHICH WAS
NOT EVEN CLOSE. USING THE RAP AND EXTRAPOLATION OF THAT MODEL...HAVE
CARRIED CLOUDY SKIES THROUGH TONIGHT. OVERALL IMPACT TO FORECAST IS
NOT HUGE. TEMPS WILL REMAIN FAIRLY STEADY TODAY /MID 20S WEST TO MID
30S EAST/ AND MIN TEMPS TONIGHT MAY JUST STAY IN THE 20S DUE TO THE
EXTENSIVE CLOUDS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM EST MON DEC 17 2012
LOW PRESSURE RESTING OVER THE UPPER GREAT LAKES EARLY THIS MORNING
WILL CONTINUE TO MOVE NORTHEASTWARD INTO THE NEW ENGLAND STATES AND
NORTHERN ONTARIO. AS IT DOES A WEAK RIDGE OF HIGH PRESSURE ALOFT AND
AT THE SURFACE WILL SLIDE INTO THE AREA...AND REMAIN THROUGH LATE
MONDAY NIGHT. THAT BEING SAID...WITH LACK OF ANY MENTIONABLE SYSTEMS
IN THE AREA...THE WEATHER WILL BE FAIRLY QUIET FOR THE START OF THE
WORK WEEK.
BEHIND THE EXITING SHORTWAVE...MOISTURE WILL BE SLOW TO EXIT...AS
925-850MB DEWPOINT DEPRESSIONS ARE AROUND 1-2C THROUGH MONDAY
MORNING ACROSS MUCH OF THE CWA. COLD AIR WILL FILTER INTO THE
WESTERN CWA ON WESTERLY TO NORTHWESTERLY WINDS THROUGHOUT THE DAY
TODAY...EVENTUALLY REACHING -8C TO -9C. GIVEN THE LINGERING MOISTURE
AND LAKE TEMP-850MB TEMP DIFFERENCE OF AROUND 12C-14C THINKING
WESTERN UPPER MICHIGAN AND FAR EASTERN UPPER MICHIGAN WILL SEE SOME
LAKE EFFECT SNOW SHOWERS. SNOW SHOWERS WILL SLOWLY BECOME MORE
ISOLATED LATE MONDAY AFTERNOON INTO MONDAY EVENING AS THE DRIEST AIR
AND ANTICYCLONIC FLOW SETTLE INTO THE REGION. THINKING THERE COULD
BE SOME BREAKS IN CLOUD COVER MONDAY AFTERNOON SOUTH CENTRAL AND
WEST WITH THIS DRYING...BUT EXPECT AREAS NEAR LAKE
SUPERIOR...ESPECIALLY FURTHEST EAST...WILL STAY CLOUDY. ANY BROKEN
SPOTS WILL QUICKLY DIMINISH LATE MONDAY NIGHT AS ANOTHER SHORTWAVE
APPROACHES THE REGION AND WINDS BECOME MORE SOUTHERLY.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 406 AM EST MON DEC 17 2012
A SURFACE LOW IS EXPECTED TO BE ALONG THE U.S./CANADIAN BORDER NEAR
NORTHWEST ND AT THE START OF THE PERIOD. A WEAK SURFACE TROUGH
STRETCHING ESE FROM THIS LOW WILL MOVE THROUGH THE CWA TUESDAY
AFTERNOON/EVENING...BUT DECAYS AS THE UPPER ENERGY WEAKENS AND
SHIFTS TO THE NORTHEAST. MEANWHILE...ANOTHER WEAK LOW OVER THE
CENTRAL MISSISSIPPI VALLEY WILL SHIFT EAST TOWARDS SOUTHERN LAKE
MICHIGAN AND DISSIPATE. WITH THE BULK OF THE ENERGY SPLITTING THE
CWA...DON/T EXPECT MUCH CHANCE FOR PRECIPITATION AND FEEL THAT THE
GOING SLIGHT CHANCES ARE REASONABLE FOR THE BROAD/WEAK WAA AND WILL
FOLLOW SUIT. ONCE THIS SHIFTS TO THE NORTHEAST TUESDAY NIGHT INTO
WEDNESDAY MORNING...AREA WILL BE BETWEEN SYSTEMS AND SHOULD LEAD TO
A QUIET DAY ON WEDNESDAY. WITH THE COLD AIR LOCKED WELL TO THE NORTH
OF THE AREA...ABOVE NORMAL TEMPERATURES WILL CONTINUE TUESDAY AND
WEDNESDAY.
ATTENTION THEN TURNS TO THE STRONG LOW PRESSURE SYSTEM TO AFFECT THE
GREAT LAKES REGION THURSDAY AND THURSDAY NIGHT...WITH THE STRONG
N-NW FLOW LAKE EFFECT INTO THE WEEKEND. WAVE CURRENTLY SOUTH OF
ALASKA AND OVER THE PACIFIC WILL BE THE ONE TO WATCH AS IT MOVES
INTO THE WESTERN CONUS ON TUESDAY AND THEN INTO THE CENTRAL PLAINS
ON WEDNESDAY NIGHT. AS THE TROUGH EXITS INTO THE GREAT LAKES
REGION...IT IS EXPECTED TO BECOME NEGATIVELY TILTED AND SEND A LOW
THROUGH THE CENTRAL GREAT LAKES. WHERE THIS LOW TRACKS WILL
DETERMINE MUCH OF THE SNOWFALL POTENTIAL FOR UPPER MICHIGAN ON
THURSDAY AND THURSDAY NIGHT.
ALL OF THE MODELS SEEM TO HAVE THE SAME IDEA WITH THE LOW
DEVELOPING AND MOVING THROUGH THE CENTRAL GREAT LAKES...IT/S JUST
PINNING DOWN THE EXACT TRACK THAT THEY ARE STRUGGLING WITH. ECMWF
SEEMS TO BE THE MOST CONSISTENT OVER THE LAST 4-5 RUNS...WHILE THE
GEM/GFS/UKMET HAVE BEEN BOUNCING AROUND IN BOTH SPEED AND
LOCATION. THE ECMWF TRACK...WHICH HAS STRONG SUPPORT FROM IT/S
ENSEMBLE MEMBERS AND ALSO THE RECENT GEM AND GEM ENSEMBLE MEAN
TRACKS THE LOW THROUGH SOUTHEAST LOWER MICHIGAN THURSDAY AFTERNOON
AND EVENING. MEANWHILE...THE LATEST GFS TRACKS IT ACROSS NORTHERN
LOWER MICHIGAN AND HAS SUPPORT OF IT/S ENSEMBLE MEMBERS AND THE
UKMET. WITH THE SYSTEM OVER THE OCEAN AND NEAR ALASKA...WANT TO
TREND TOWARDS THE ECMWF DUE TO CONSISTENCY AND IT/S SUPERIOR
HANDLING/INITIALIZING OF SATELLITE DATA IN THAT AREA. IN
ADDITION...WITH THE TROUGH NOT DIGGING TOO DEEP AND WITH LIMITED
COLD AIR SPILLING SOUTH WITH THE TROUGH...WONDER IF THE SOUTHERN
SOLN WILL PAN OUT COMPARED TO MORE COLD AIR SHARPENING THE UPPER
TROUGH IN A MORE TRADITIONAL WINTER WEATHER SITUATION. BUT WITH THE
POTENTIAL HIGH IMPACT...FEEL THAT FOLLOWING A GENERAL CONSENSUS
FROM THE GFS/ECMWF/GEM IS THE WAY TO GO AT THIS POINT.
THIS GENERAL CONSENSUS WOULD PUSH AN INITIAL WAVE OF WAA
PRECIPITATION ACROSS THE EASTERN HALF OF THE CWA LATE WEDNESDAY
NIGHT AND INTO THURSDAY AND THEN TRANSITION TO LAKE ENHANCE
SNOW NEAR LAKE SUPERIOR WHILE THE TROWAL TRACKS ACROSS NORTHERN
LAKE MICHIGAN OR NORTHWEST LOWER MICHIGAN. AS FOR THE SYNOPTIC
PRECIPITATION...OVERALL CONSENSUS WOULD HAVE THE HIGHEST AMOUNTS
NEAR THE LAKE MICHIGAN SHORELINE AND GENERALLY HIGH END ADVISORY
SNOWFALL AMOUNTS EAST OF A LINE FROM ISHPEMING TO IRON MOUNTAIN.
WHEN FACTORING IN THE WIND AND SOME BLOWING SNOW COULD SEE SOME
HIGHER HEADLINES. THEREFORE...WILL CONTINUE TO MENTION IN THE HWO
AND TOP NEWS STORIES.
THE OTHER FACTOR WITH THIS SYSTEM IS LAKE ENHANCEMENT OFF LAKE
SUPERIOR AS WINDS TURN TO THE NORTH ON THURSDAY AND THEN TO THE
NORTHWEST THURSDAY NIGHT. BEST DEEP MOISTURE FOR LAKE ENHANCEMENT
LOOKS TO BE FROM MARQUETTE COUNTY AND EASTWARD ON THURSDAY AFTERNOON
INTO THURSDAY NIGHT. HAVEN/T HAD ANY GOOD CLEAR DAYS TO GET A RECENT
SATELLITE ESTIMATE OF THE LAKE SUPERIOR TEMPS...BUT GLERL ANALYSIS
INDICATES VALUES IN THE 3-4C RANGE WHICH WOULD PRODUCE DELTA-T
VALUES OF 10-12. WITH THE WIND DIRECTIONS THURSDAY AFTERNOON
INTO THURSDAY NIGHT...THINK THE BEST LOCATIONS FOR LAKE ENHANCEMENT
WILL BE OVER MARQUETTE/ALGER COUNTIES WITH THE NORTHERLY WINDS
TAPPING INTO THE LONGEST FETCH AND SOME ENHANCED CONVERGENCE WITH
THE BACKING CYCLONIC FLOW THROUGH THURSDAY NIGHT. AS HAS BEEN THE
CASE THIS WINTER...THE LIMITED AMOUNT OF COLD AIR BEHIND THE
SYSTEM LEADS TO UNCERTAINTY IN THE AMOUNT OF LAKE ENHANCEMENT AND
RESULTING SNOWFALL AMOUNTS. FARTHER WEST THE SNOW POTENTIAL IS UP IN
THE AIR...AS IT WILL LARGELY DEPEND ON THE LOW TRACK TO PROVIDE
ENOUGH MOISTURE FOR LAKE ENHANCE/EFFECT SNOW. THIS LAKE ENHANCE SNOW
SHOULD CONTINUE INTO FRIDAY ALTHOUGH IT IS EXPECTED TO DIMINISH INTO
THE AFTERNOON AS THE DEEPER MOISTURE DEPARTS AND AN UPPER RIDGE
BEGINS TO BUILD INTO THE AREA.
AFTER THE SYSTEM SHIFTS TO THE NORTHEAST ON FRIDAY...EXPECT THE
AREA TO BE UNDER PERSISTANT N-NW FLOW INTO THE WEEKEND. THIS IS DUE
TO THE UPPER TROUGH BECOMING CLOSED OFF AND STALLING OVER THE NEW
ENGLAND STATES IN RESPONSE TO AN UPSTREAM UPPER LOW SE OF
GREENLAND. THIS WILL PUT THE CWA BETWEEN THE EXITING SURFACE LOW
AND HIGH PRESSURE CENTERED OVER LAKE WINNIPEG. LES LOCATIONS WILL
DEPEND ON HOW THE PRESSURE FIELD SETS UP...BUT AT THIS POINT IT
LOOKS LIKE NORTHERLY WIND LOCATIONS ON THURSDAY NIGHT WITH THE LAKE
ENHANCEMENT...THEN TRANSFERRING TO NORTHWEST FLOW LAKE EFFECT ON
FRIDAY AND CONTINUING INTO THE WEEKEND. INITIAL LOOK WOULD SUPPORT
THE POTENTIAL FOR PERSISTENT LAKE EFFECT DURING THIS PERIOD...BUT
THERE ARE SEVERAL FACTORS THAT ARE LIKELY TO LIMIT THE INTENSITY.
THE FIRST LIMITING FACTOR IS THE LIMITED AMOUNT OF COLD AIR...WHICH
THE BUILDING RIDGE ON FRIDAY AFTERNOON THROUGH SATURDAY MORNING
WORKS TO PUT DELTA-T VALUES IN THE 9-13 RANGE. SECOND...THE
SUBSIDENCE INVERSION TAKES HOLD ON FRIDAY NIGHT /INVERSION HEIGHTS
FALL TO 4KFT/ WITH THE SYSTEM SHIFTING TO THE EAST. THIS SHOULD
GREATLY DIMINISH LES INTENSITY THROUGH THE NIGHT AND INTO SATURDAY.
AND THIRD IS THAT THE STRONG WINDS ON FRIDAY INTO FRIDAY NIGHT WILL
LEAD TO LESS RESIDENCE TIME OVER LAKE SUPERIOR AND ALSO CAUSE
FRACTURING OF ANY LARGER DENDRITIC SNOWFLAKES...ALTHOUGH THERE MAY
NOT BE TOO MANY BASED OFF BUFKIT SOUNDINGS. THEREFORE...HAVE
DIMINISHED THE POPS THROUGH THE DAY FRIDAY AND INTO SATURDAY MORNING
BEFORE SECOND WAVE MOVES THROUGH SAT AFTERNOON INTO SAT
NIGHT...PROVIDING SOME ADDITIONAL DEEPER MOISTURE. THE AMOUNT OF
MOISTURE AND TIMING OF THE WAVE DIFFERS IN THE MODELS...SO WILL JUST
KEEP LOW CHANCE POPS IN THE NORTHWEST WIND FAVORED LOCATIONS INTO
SUNDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1233 PM EST MON DEC 17 2012
EXPECT LOW MVFR CLOUD DECK TO PERSIST THROUGH THE REST OF THE DAY
AS MOISTURE THROUGH 3-4KFT IS TRAPPED BENEATH SUBSIDENCE INVERSION.
LIMITED DRY AIR ADVECTION AND LOW SUN ANGLE FOR MID DECEMBER WILL NOT
HELP MIX OUT THE CLOUDS TODAY AS WELL. CIGS AT ALL SITES SHOULD
TRANSITION TO AN OVC VFR MID CLOUD DECK LATER TONIGHT INTO TUESDAY AS
WINDS BECOME MORE SOUTHWEST TO SOUTH HELPING TO SCOUR OUT LOW-LEVEL
MOISTURE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 406 AM EST MON DEC 17 2012
AS HIGH PRESSURE SHIFTS INTO THE AREA TODAY...WEST TO NORTHWEST
WINDS OF 15 TO 25 KTS WILL DIE DOWN TO GENERALLY LESS THAN 15 KTS BY
LATE TONIGHT.
MAIN TIME OF CONCERN FOR THE MARINE FORECAST IS DURING THE END OF
THE WEEK AS A LOW PRESSURE SYSTEM MOVES THROUGH THE CENTRAL GREAT
LAKES. SEEMS VERY LIKELY THAT NORTH TO NORTHWEST GALES OF
35-40KTS WILL OCCUR OVER MUCH OF THE LAKE THURSDAY INTO FRIDAY. THE
NORTHWEST WINDS WILL REMAIN IN PLACE INTO THE WEEKEND...ALTHOUGH T
THEY SHOULD ONLY BE 20-30KTS...AS LAKE SUPERIOR IS SITUATED BETWEEN
THE LOW OVER THE NEW ENGLAND STATES AND HIGH PRESSURE OVER LAKE
WINNIPEG.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...MCD
LONG TERM...SRF
AVIATION...JLA
MARINE...MCD/SRF
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1129 AM EST MON DEC 17 2012
.UPDATE...
ISSUED AT 1120 AM EST MON DEC 17 2012
SHORTWAVE THAT BROUGHT LGT SNOW/FLURRIES TO NORTHERN CWA EARLIER
THIS MORNING IS SLIDING OVR FAR EASTERN LK SUPERIOR NEAR WHITEFISH
POINT/SAULT STE MARIE. FEATURE PRETTY IMPRESSIVE LOOKING ON WV WITH
TIGHT SPIN NOTED. CANADIAN RADAR/SFC OBS SHOWING WIDESPREAD LGT
PRECIP FM ERY TO ANJ. VSBY AT ERY NOW DOWN TO 4SM...INDICATING SNOW
IS INTENSIFYING SOME. COULD SEE ADDITIONAL SNOW ACCUMS UP TO 1 INCH
THROUGH EARLY AFTN...BUT WOULD BE PRETTY LOCALIZED OVR NORTHERN LUCE
COUNTY. SEEMS LIKE RAIN/SNOW MIX SEEN AT CYAM/ANJ THIS MORNING IS
STAYING JUST TO NORTH OF ERY TOWARD WHITEFISH POINT. ELSEWHERE JUST A
FEW FLURRIES/SNOW SHOWERS ARE ONGOING OVR NCNTRL CWA AND MAYBE KEWEENAW
TOO...THOUGH CMX HAS NOT REPORTED ANYTHING IN A WHILE. GOING POPS
WERE IN FINE SHAPE...LITTLE CHANGES MADE THERE. LINGERING LGT SNOW
SHOULD BE EXITING THE EASTERN CWA THIS EVENING.
BASED ON 12Z SOUNDING FM GRB SHOWING MOISTURE UP TO 875MB TRAPPED
BENEATH INCREASING SUBSIDENCE INVERSION...LOW SUN ANGLE IN MID
DECEMBER AND LACK OF DRY AIR ADVECTION INTO REGION...HAVE KEPT SKIES
CLOUDY THROUGH THE DAY AND EVEN INTO TONIGHT. RAP ONLY MODEL THAT
HAD GOOD HANDLE ON DEPTH OF MOISTURE. NAM SOUNDING AT GRB FOR 12Z
SHOWED THIN LAYER OF MOISTURE AT 950MB WITH DRYING ABOVE...WHICH WAS
NOT EVEN CLOSE. USING THE RAP AND EXTRAPOLATION OF THAT MODEL...HAVE
CARRIED CLOUDY SKIES THROUGH TONIGHT. OVERALL IMPACT TO FORECAST IS
NOT HUGE. TEMPS WILL REMAIN FAIRLY STEADY TODAY /MID 20S WEST TO MID
30S EAST/ AND MIN TEMPS TONIGHT MAY JUST STAY IN THE 20S DUE TO THE
EXTENSIVE CLOUDS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM EST MON DEC 17 2012
LOW PRESSURE RESTING OVER THE UPPER GREAT LAKES EARLY THIS MORNING
WILL CONTINUE TO MOVE NORTHEASTWARD INTO THE NEW ENGLAND STATES AND
NORTHERN ONTARIO. AS IT DOES A WEAK RIDGE OF HIGH PRESSURE ALOFT AND
AT THE SURFACE WILL SLIDE INTO THE AREA...AND REMAIN THROUGH LATE
MONDAY NIGHT. THAT BEING SAID...WITH LACK OF ANY MENTIONABLE SYSTEMS
IN THE AREA...THE WEATHER WILL BE FAIRLY QUIET FOR THE START OF THE
WORK WEEK.
BEHIND THE EXITING SHORTWAVE...MOISTURE WILL BE SLOW TO EXIT...AS
925-850MB DEWPOINT DEPRESSIONS ARE AROUND 1-2C THROUGH MONDAY
MORNING ACROSS MUCH OF THE CWA. COLD AIR WILL FILTER INTO THE
WESTERN CWA ON WESTERLY TO NORTHWESTERLY WINDS THROUGHOUT THE DAY
TODAY...EVENTUALLY REACHING -8C TO -9C. GIVEN THE LINGERING MOISTURE
AND LAKE TEMP-850MB TEMP DIFFERENCE OF AROUND 12C-14C THINKING
WESTERN UPPER MICHIGAN AND FAR EASTERN UPPER MICHIGAN WILL SEE SOME
LAKE EFFECT SNOW SHOWERS. SNOW SHOWERS WILL SLOWLY BECOME MORE
ISOLATED LATE MONDAY AFTERNOON INTO MONDAY EVENING AS THE DRIEST AIR
AND ANTICYCLONIC FLOW SETTLE INTO THE REGION. THINKING THERE COULD
BE SOME BREAKS IN CLOUD COVER MONDAY AFTERNOON SOUTH CENTRAL AND
WEST WITH THIS DRYING...BUT EXPECT AREAS NEAR LAKE
SUPERIOR...ESPECIALLY FURTHEST EAST...WILL STAY CLOUDY. ANY BROKEN
SPOTS WILL QUICKLY DIMINISH LATE MONDAY NIGHT AS ANOTHER SHORTWAVE
APPROACHES THE REGION AND WINDS BECOME MORE SOUTHERLY.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 406 AM EST MON DEC 17 2012
A SURFACE LOW IS EXPECTED TO BE ALONG THE U.S./CANADIAN BORDER NEAR
NORTHWEST ND AT THE START OF THE PERIOD. A WEAK SURFACE TROUGH
STRETCHING ESE FROM THIS LOW WILL MOVE THROUGH THE CWA TUESDAY
AFTERNOON/EVENING...BUT DECAYS AS THE UPPER ENERGY WEAKENS AND
SHIFTS TO THE NORTHEAST. MEANWHILE...ANOTHER WEAK LOW OVER THE
CENTRAL MISSISSIPPI VALLEY WILL SHIFT EAST TOWARDS SOUTHERN LAKE
MICHIGAN AND DISSIPATE. WITH THE BULK OF THE ENERGY SPLITTING THE
CWA...DON/T EXPECT MUCH CHANCE FOR PRECIPITATION AND FEEL THAT THE
GOING SLIGHT CHANCES ARE REASONABLE FOR THE BROAD/WEAK WAA AND WILL
FOLLOW SUIT. ONCE THIS SHIFTS TO THE NORTHEAST TUESDAY NIGHT INTO
WEDNESDAY MORNING...AREA WILL BE BETWEEN SYSTEMS AND SHOULD LEAD TO
A QUIET DAY ON WEDNESDAY. WITH THE COLD AIR LOCKED WELL TO THE NORTH
OF THE AREA...ABOVE NORMAL TEMPERATURES WILL CONTINUE TUESDAY AND
WEDNESDAY.
ATTENTION THEN TURNS TO THE STRONG LOW PRESSURE SYSTEM TO AFFECT THE
GREAT LAKES REGION THURSDAY AND THURSDAY NIGHT...WITH THE STRONG
N-NW FLOW LAKE EFFECT INTO THE WEEKEND. WAVE CURRENTLY SOUTH OF
ALASKA AND OVER THE PACIFIC WILL BE THE ONE TO WATCH AS IT MOVES
INTO THE WESTERN CONUS ON TUESDAY AND THEN INTO THE CENTRAL PLAINS
ON WEDNESDAY NIGHT. AS THE TROUGH EXITS INTO THE GREAT LAKES
REGION...IT IS EXPECTED TO BECOME NEGATIVELY TILTED AND SEND A LOW
THROUGH THE CENTRAL GREAT LAKES. WHERE THIS LOW TRACKS WILL
DETERMINE MUCH OF THE SNOWFALL POTENTIAL FOR UPPER MICHIGAN ON
THURSDAY AND THURSDAY NIGHT.
ALL OF THE MODELS SEEM TO HAVE THE SAME IDEA WITH THE LOW
DEVELOPING AND MOVING THROUGH THE CENTRAL GREAT LAKES...IT/S JUST
PINNING DOWN THE EXACT TRACK THAT THEY ARE STRUGGLING WITH. ECMWF
SEEMS TO BE THE MOST CONSISTENT OVER THE LAST 4-5 RUNS...WHILE THE
GEM/GFS/UKMET HAVE BEEN BOUNCING AROUND IN BOTH SPEED AND
LOCATION. THE ECMWF TRACK...WHICH HAS STRONG SUPPORT FROM IT/S
ENSEMBLE MEMBERS AND ALSO THE RECENT GEM AND GEM ENSEMBLE MEAN
TRACKS THE LOW THROUGH SOUTHEAST LOWER MICHIGAN THURSDAY AFTERNOON
AND EVENING. MEANWHILE...THE LATEST GFS TRACKS IT ACROSS NORTHERN
LOWER MICHIGAN AND HAS SUPPORT OF IT/S ENSEMBLE MEMBERS AND THE
UKMET. WITH THE SYSTEM OVER THE OCEAN AND NEAR ALASKA...WANT TO
TREND TOWARDS THE ECMWF DUE TO CONSISTENCY AND IT/S SUPERIOR
HANDLING/INITIALIZING OF SATELLITE DATA IN THAT AREA. IN
ADDITION...WITH THE TROUGH NOT DIGGING TOO DEEP AND WITH LIMITED
COLD AIR SPILLING SOUTH WITH THE TROUGH...WONDER IF THE SOUTHERN
SOLN WILL PAN OUT COMPARED TO MORE COLD AIR SHARPENING THE UPPER
TROUGH IN A MORE TRADITIONAL WINTER WEATHER SITUATION. BUT WITH THE
POTENTIAL HIGH IMPACT...FEEL THAT FOLLOWING A GENERAL CONSENSUS
FROM THE GFS/ECMWF/GEM IS THE WAY TO GO AT THIS POINT.
THIS GENERAL CONSENSUS WOULD PUSH AN INITIAL WAVE OF WAA
PRECIPITATION ACROSS THE EASTERN HALF OF THE CWA LATE WEDNESDAY
NIGHT AND INTO THURSDAY AND THEN TRANSITION TO LAKE ENHANCE
SNOW NEAR LAKE SUPERIOR WHILE THE TROWAL TRACKS ACROSS NORTHERN
LAKE MICHIGAN OR NORTHWEST LOWER MICHIGAN. AS FOR THE SYNOPTIC
PRECIPITATION...OVERALL CONSENSUS WOULD HAVE THE HIGHEST AMOUNTS
NEAR THE LAKE MICHIGAN SHORELINE AND GENERALLY HIGH END ADVISORY
SNOWFALL AMOUNTS EAST OF A LINE FROM ISHPEMING TO IRON MOUNTAIN.
WHEN FACTORING IN THE WIND AND SOME BLOWING SNOW COULD SEE SOME
HIGHER HEADLINES. THEREFORE...WILL CONTINUE TO MENTION IN THE HWO
AND TOP NEWS STORIES.
THE OTHER FACTOR WITH THIS SYSTEM IS LAKE ENHANCEMENT OFF LAKE
SUPERIOR AS WINDS TURN TO THE NORTH ON THURSDAY AND THEN TO THE
NORTHWEST THURSDAY NIGHT. BEST DEEP MOISTURE FOR LAKE ENHANCEMENT
LOOKS TO BE FROM MARQUETTE COUNTY AND EASTWARD ON THURSDAY AFTERNOON
INTO THURSDAY NIGHT. HAVEN/T HAD ANY GOOD CLEAR DAYS TO GET A RECENT
SATELLITE ESTIMATE OF THE LAKE SUPERIOR TEMPS...BUT GLERL ANALYSIS
INDICATES VALUES IN THE 3-4C RANGE WHICH WOULD PRODUCE DELTA-T
VALUES OF 10-12. WITH THE WIND DIRECTIONS THURSDAY AFTERNOON
INTO THURSDAY NIGHT...THINK THE BEST LOCATIONS FOR LAKE ENHANCEMENT
WILL BE OVER MARQUETTE/ALGER COUNTIES WITH THE NORTHERLY WINDS
TAPPING INTO THE LONGEST FETCH AND SOME ENHANCED CONVERGENCE WITH
THE BACKING CYCLONIC FLOW THROUGH THURSDAY NIGHT. AS HAS BEEN THE
CASE THIS WINTER...THE LIMITED AMOUNT OF COLD AIR BEHIND THE
SYSTEM LEADS TO UNCERTAINTY IN THE AMOUNT OF LAKE ENHANCEMENT AND
RESULTING SNOWFALL AMOUNTS. FARTHER WEST THE SNOW POTENTIAL IS UP IN
THE AIR...AS IT WILL LARGELY DEPEND ON THE LOW TRACK TO PROVIDE
ENOUGH MOISTURE FOR LAKE ENHANCE/EFFECT SNOW. THIS LAKE ENHANCE SNOW
SHOULD CONTINUE INTO FRIDAY ALTHOUGH IT IS EXPECTED TO DIMINISH INTO
THE AFTERNOON AS THE DEEPER MOISTURE DEPARTS AND AN UPPER RIDGE
BEGINS TO BUILD INTO THE AREA.
AFTER THE SYSTEM SHIFTS TO THE NORTHEAST ON FRIDAY...EXPECT THE
AREA TO BE UNDER PERSISTANT N-NW FLOW INTO THE WEEKEND. THIS IS DUE
TO THE UPPER TROUGH BECOMING CLOSED OFF AND STALLING OVER THE NEW
ENGLAND STATES IN RESPONSE TO AN UPSTREAM UPPER LOW SE OF
GREENLAND. THIS WILL PUT THE CWA BETWEEN THE EXITING SURFACE LOW
AND HIGH PRESSURE CENTERED OVER LAKE WINNIPEG. LES LOCATIONS WILL
DEPEND ON HOW THE PRESSURE FIELD SETS UP...BUT AT THIS POINT IT
LOOKS LIKE NORTHERLY WIND LOCATIONS ON THURSDAY NIGHT WITH THE LAKE
ENHANCEMENT...THEN TRANSFERRING TO NORTHWEST FLOW LAKE EFFECT ON
FRIDAY AND CONTINUING INTO THE WEEKEND. INITIAL LOOK WOULD SUPPORT
THE POTENTIAL FOR PERSISTENT LAKE EFFECT DURING THIS PERIOD...BUT
THERE ARE SEVERAL FACTORS THAT ARE LIKELY TO LIMIT THE INTENSITY.
THE FIRST LIMITING FACTOR IS THE LIMITED AMOUNT OF COLD AIR...WHICH
THE BUILDING RIDGE ON FRIDAY AFTERNOON THROUGH SATURDAY MORNING
WORKS TO PUT DELTA-T VALUES IN THE 9-13 RANGE. SECOND...THE
SUBSIDENCE INVERSION TAKES HOLD ON FRIDAY NIGHT /INVERSION HEIGHTS
FALL TO 4KFT/ WITH THE SYSTEM SHIFTING TO THE EAST. THIS SHOULD
GREATLY DIMINISH LES INTENSITY THROUGH THE NIGHT AND INTO SATURDAY.
AND THIRD IS THAT THE STRONG WINDS ON FRIDAY INTO FRIDAY NIGHT WILL
LEAD TO LESS RESIDENCE TIME OVER LAKE SUPERIOR AND ALSO CAUSE
FRACTURING OF ANY LARGER DENDRITIC SNOWFLAKES...ALTHOUGH THERE MAY
NOT BE TOO MANY BASED OFF BUFKIT SOUNDINGS. THEREFORE...HAVE
DIMINISHED THE POPS THROUGH THE DAY FRIDAY AND INTO SATURDAY MORNING
BEFORE SECOND WAVE MOVES THROUGH SAT AFTERNOON INTO SAT
NIGHT...PROVIDING SOME ADDITIONAL DEEPER MOISTURE. THE AMOUNT OF
MOISTURE AND TIMING OF THE WAVE DIFFERS IN THE MODELS...SO WILL JUST
KEEP LOW CHANCE POPS IN THE NORTHWEST WIND FAVORED LOCATIONS INTO
SUNDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 630 AM EST MON DEC 17 2012
UPDATE AT 1130 AM EST...EXPECT CLOUDS TO PERSIST THROUGH TONIGHT AS
MOISTURE THROUGH 3-4KFT IS TRAPPED BENEATH SUBSIDENCE INVERSION.
LIMITED DRY AIR ADVECTION AND LOW SUN ANGLE FOR MID DECEMBER WILL NOT
HELP MIX OUT THE CLOUDS TODAY EITHER. CIGS SHOULD REMAIN IFR AT IWD
UNTIL TONIGHT WHEN THEY SHOULD TRANSITION TO VFR MID CLOUDS AS WINDS
BECOME MORE SOUTHWEST HELPING TO SCATTER OUT THE LOW CLOUDS. SIMILAR
FATE FOR THE CURRENT MVFR CLOUD DECK IS EXPECTED TONIGHT AT CMX AND
SAW. EXPECT OVC VFR MID CLOUD DECK BY SUNRISE TUESDAY AT ALL THE TAF
SITES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 406 AM EST MON DEC 17 2012
AS HIGH PRESSURE SHIFTS INTO THE AREA TODAY...WEST TO NORTHWEST
WINDS OF 15 TO 25 KTS WILL DIE DOWN TO GENERALLY LESS THAN 15 KTS BY
LATE TONIGHT.
MAIN TIME OF CONCERN FOR THE MARINE FORECAST IS DURING THE END OF
THE WEEK AS A LOW PRESSURE SYSTEM MOVES THROUGH THE CENTRAL GREAT
LAKES. SEEMS VERY LIKELY THAT NORTH TO NORTHWEST GALES OF
35-40KTS WILL OCCUR OVER MUCH OF THE LAKE THURSDAY INTO FRIDAY. THE
NORTHWEST WINDS WILL REMAIN IN PLACE INTO THE WEEKEND...ALTHOUGH T
THEY SHOULD ONLY BE 20-30KTS...AS LAKE SUPERIOR IS SITUATED BETWEEN
THE LOW OVER THE NEW ENGLAND STATES AND HIGH PRESSURE OVER LAKE
WINNIPEG.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...MCD
LONG TERM...SRF
AVIATION...JLA
MARINE...MCD/SRF
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1012 AM EST MON DEC 17 2012
.SYNOPSIS...
ISSUED AT 315 AM EST MON DEC 17 2012
LOW PRESSURE OVER EASTERN LAKE SUPERIOR WILL WEAKEN AND MOVE TOWARD
JAMES BAY TODAY. CHANCES FOR RAIN AND SNOW WILL CONTINUE TO DECREASE
THROUGH TONIGHT AS THIS OCCURS. A WEAK LOW PRESSURE SYSTEM PASSING
TO OUR SOUTH MAY BRING LIGHT RAIN AND SNOW TUESDAY AFTERNOON INTO
TUESDAY NIGHT. A MUCH STRONGER SYSTEM WILL MOVE INTO THE REGION
THURSDAY...WITH WINTER STORM CONDITIONS EXPECTED IN AT LEAST SOME
PARTS OF THE GREAT LAKES REGION.
&&
.UPDATE...
ISSUED AT 1009 AM EST MON DEC 17 2012
BROAD TROUGHINESS REMAINS OVER THE GREAT LAKES...WITH ONE RATHER
COMPACT EMBEDDED VORT LOBE EXITING EASTERN UPPER MICHIGAN. LOW LEVEL
MOISTURE REMAINS ABUNDANT...AS EVIDENT BY WIDESPREAD STRATUS AND 12Z
LOCAL SOUNDING WHICH HAD A MOISTURE-RICH PROFILE UP THROUGH H80.
TOP-DOWN DRYING ALREADY EVIDENT JUST UPSTREAM...WITH KGRB SOUNDING
SHOWING RAPID DEPLETION OF MOISTURE ABOVE H85 CENTERED INVERSION.
THIS DRYING WILL CONTINUE TO SPREAD EAST...WITH A RAPID FALL-OFF OF
MID LEVEL MOISTURE INTO THIS AFTERNOON...ESPECIALLY ACROSS NORTHERN
LOWER MICHIGAN. COMBINE THIS WITH JUST MARGINALLY UNSTABLE LOW LEVEL
PROFILES OVER LAKE MICHIGAN (HIGH RES RAP ANALYSIS SHOWED -6C H85
AIR OVER THE BIG POND)...AND ONGOING LIGHT LAKE EFFECT SNOW/RAIN
SHOWERS SHOULD TAPER OFF THROUGH EARLY AFTERNOON. MOISTURE REMAINS
SOMEWHAT DEEPER OVER LAKE SUPERIOR...SUGGESTING LIGHT RAIN/SNOW
SHOWERS CONTINUING THROUGH MUCH OF THIS AFTERNOON...PERHAPS BRINGING
SOME VERY MINOR SNOW ACCUMULATIONS (SUB ONE INCH) OVER THE FAVORED
SNOWBELTS. TEMPERATURES LOOK TO REMAIN PRETTY STEADY-STATE IN THE
MID AND UPPER 30S AS DIURNAL INFLUENCES ARE COUNTERED BY WEAKISH LOW
LEVEL CAA. ABOVE WELL HANDLED BY INHERITED FORECAST WITH ONLY
COSMETIC CHANGES NEEDED TO ACCOUNT FOR REAL-TIME RADAR TRENDS.
UPDATE ISSUED AT 700 AM EST MON DEC 17 2012
SOME FINE-TUNING...PUSHING MORNING POPS A LITTLE FURTHER SOUTH
INTO THE HTL/CAD AREAS...AND KEEPING PRECIP MIXED A FEW MORE HOURS
IN EASTERN UPPER BEFORE GOING ALL SNOW. NEWLY ARRIVING STAFF
MEMBERS REPORT SEEING A FEW WET FLAKES MIXING IN ON THE
COMMUTE...SO HAVE ADDED IN A MIX A BIT SOONER OVER THE HIGH
TERRAIN IN THE GLR AREA.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 315 AM EST MON DEC 17 2012
RATHER NEBULOUS FORECAST AS WE WELCOME THE NEW WORK WEEK...WITH MAIN
ISSUES BEING CLOUD COVER/TEMPS AND SMALL CHANCES FOR MAINLY NUISANCE
LAKE SNOW SHOWERS/FLURRIES. EARLY MORNING ANALYSIS PLACES WEAK
SURFACE LOW OVER THE EASTERN TIP OF LAKE SUPERIOR...WITH ITS
ASSOCIATED WEAK OCCLUDED FRONTAL BOUNDARY SLOWLY WORKING THROUGH
NORTHERN LOWER. JUST A SUBTLE WIND SHIFT WITH THIS FEATURE...BUT
WITH A SLIGHTLY COOLER AIR MASS GRADUALLY FILTERING INTO THE CWA
(STILL NOT VERY COLD FOR MID DECEMBER). REGIONAL RADAR MOSAIC SHOWS
EARLIER LAST BATCH OF SHOWERS EXITING THE AREA...AS WEAK SECONDARY
UPPER VORT IS TRACKING OVERHEAD...WHILE SATELLITE PICS/OBS SHOW
QUITE THE EXPANSIVE LOW STRATUS CLOUD DECK WELL ENTRENCHED ALL
THROUGHOUT THE GREAT LAKES/UPPER MIDWEST.
FOR TODAY...BROAD UPPER TROUGHING WILL CONTINUE TO DOMINATE THE
GREAT LAKES REGION...AS STRONGER SOUTHERN STREAM ENERGY LIFTS
THROUGH THE TENNESSEE VALLEY. AIRMASS THROUGH THE DAY WILL BECOME
INCREASINGLY COOL ALOFT (H8 TEMPS AROUND -6C BY MIDDAY) WHILE ALSO
DRYING OUT ACROSS NORTHERN LOWER. EASTERN UPPER WILL BE A DIFFERENT
STORY AS APPROACH OF YET ANOTHER WEAK SHORTWAVE BRINGS A BRIEF ROUND
OF DEEPER MOISTURE ACROSS EASTERN LAKE SUPERIOR. THAT SETUP IN
COMBINATION WITH MARGINAL LAKE INSTABILITY SHOULD GIVEN AT LEAST
DECENT COVERAGE OF MAINLY LIGHT LAKE SNOW SHOWERS THROUGH THE DAY
ACROSS NORTHERN CHIPPEWA COUNTY IN A MEAN WEST/NORTHWEST FLOW
REGIME. ACCUMULATIONS SHOULD BE HINDERED BY SURFACE TEMPS AT OR
SLIGHTLY ABOVE FREEZING...BUT PERHAPS UP TO AN INCH COULD FALL.
NORTHERN LOWER LOOKS MUCH MORE PALTRY AS MOISTURE IS VERY THIN AND
OVERLAKE INSTABILITY IS EVEN WORSE (DELTA T VALUES UP AROUND 12C).
THAT SETUP SHOULD GIVE US PLENTY OF LAKE STRATUS...AND MAYBE A FEW
LIGHT SNOW SHOWERS...BUT PROBABLY MORE LIKE JUST SOME FLURRIES...
WITH THOSE LIKELY TO END THROUGH THE AFTERNOON AS MOISTURE FURTHER
THINS TO BELOW 900MB. HIGHS DEFINITELY A BIT CLOSER TO NORMAL BUT
STILL ABOVE...WITH READINGS MAINLY IN THE 32-38F RANGE.
TONIGHT LOOKS EVEN MORE QUIET AS THE WEAK SURFACE LOW PROGRESSES
TOWARD JAMES BAY...WHILE STRONGER LOW PRESSURE SLIDES THROUGH THE
OHIO VALLEY. THIS WILL ALLOW LOW LEVEL RIDGING TO BUILD INTO
NORTHERN MICHIGAN THROUGH THE NIGHT. WEAKENING GRADIENT SHOULD ALLOW
FOR SOME LAND BREEZE DEVELOPMENT...THEORETICALLY HELPING PUSH SOME
OF THE LAKE STRATUS CLOSER TO THE COASTS. HOWEVER...DEGREE OF
CLEARING REMAINS TO BE SEEN...AND NOT OVERLY ENTHUSIASTIC GIVEN SUCH
WIDESPREAD STRATUS SPREAD WELL UPSTREAM THROUGH THE NORTHERN
PLAINS/UPPER MIDWEST. DON`T FORESEE MUCH IN THE WAY OF ANY LINGERING
LAKE SNOW SHOWERS AS MOISTURE IS EVEN MORE THIN...BUT SUPPOSE A
ROGUE FLURRY IS POSSIBLE. OVERNIGHT LOWS WILL BE TIED TO DEGREE OF
CLEARING...BUT GIVEN OUR RECENT HISTORY AND STRONGER LIKELIHOOD FOR
CLOUDS TO PREVAIL...FEEL WARMER IS PROBABLY BETTER...AND WILL SIDE
WITH READINGS MAINLY IN THE UPPER HALF OF THE 20S TO LOWER 30S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 315 AM EST MON DEC 17 2012
MILD AND RELATIVELY UNEVENTFUL WX WILL HOLD INTO WEDNESDAY. A
VARIETY OF OPTIONS ARE POSSIBLE AFTER THAT...THOUGH /UNEVENTFUL/
DOES NOT APPEAR TO BE ONE OF THEM. A WEAK N-S ORIENTED RIDGE AXIS
WILL BE OVER LOWER MI EARLY TUESDAY...TEMPORARILY DISLODGED BY A
VERY WEAK SURFACE WAVE TRANSITING FAR SOUTHERN LOWER MI IN THE
EVENING. SMALL PRECIP CHANCES MAY BE IN THE OFFING TUE-WED...BUT THE
MAIN SHOW WILL CLEARLY OCCUR AFTER THAT.
TUESDAY...850MB THERMAL TROF WILL BE DISPLACED EAST ACROSS LAKE
HURON DURING THE DAY...ALLOWING FOR A 2-3C RECOVERY TO -4 TO -7C.
THE STRONGEST WARM ADVECTION/ISENTROPIC ASCENT WILL FOCUS JUST TO
OUR SW...MOVING TOWARD SOUTHERN LAKE MI IN THE AFTERNOON. THIS IS IN
ADVANCE OF A 1004MB LOW MOVING EAST FROM CENTRAL IOWA TO NORTHERN
IL. FGEN FORCING WILL CONTRIBUTE TO A BAND OF MOISTENING ALOFT THAT
EVENTUALLY REACHES NE WI...CENTRAL AND SOUTHERN LOWER MI LATE. DRIER
AIR BELOW 800MB WILL BE MORE STUBBORN TO DISLODGE...BUT MODEL
SOUNDINGS ARE MORE OPTIMISTIC IN PROGGING PRECIP DOWN TO THE SURFACE
BY LATE AFTERNOON/EARLY EVENING. SO EARLIER ADDITION OF CHANCE POPS
TO PARTS OF NW LOWER MI STILL LOOKS VERY REASONABLE. WILL REMOVE A
MENTION OF MIX OVER THE HIGHER TERRAIN (CAD AREA)...WHERE SNOW
SHOULD PREVAIL IF PRECIP DEVELOPS. CLOSER TO LAKE MI (MBL/FKS)...A
RA/SN MENTION IS GOOD. PLENTY OF CLOUDS FOR MOST...COULD BE SOME
THIN SPOTS EARLY IN NE LOWER BEFORE MID/HIGH CLOUDS THICKEN. MAX
TEMPS IN THE 30S.
TUE NIGHT/WEDNESDAY...WARM ADVECTION/FGEN BAND OF MID-LEVEL MOISTURE
WILL CONTINUE TO LIFT ACROSS THE FORECAST AREA TUE NIGHT.
HOWEVER...LIFT WILL WEAKEN WITH TIME...ESPECIALLY OVERNIGHT...AS THE
WEAK SURFACE LOW REACHES LAKE ERIE AND FILLS. SMALL CHANCE POPS ARE
STILL REASONABLE FOR MUCH OF NORTHERN LOWER MI TUE EVENING (STILL
HOLDING ONTO A MIX IN COASTAL AREAS)...BUT SLIGHT CHANCE OR LESS
WILL SUFFICE BY THE TIME THE BAND LIFTS ACROSS EASTERN UPPER/FAR NE
LOWER MI OVERNIGHT. STRATUS SHOULD BE CONSIDERABLE BEHIND THE
DEPARTING BAND...BUT THERE MAY SOME BREAKS IN THE FAR SE. HIGH
PRESSURE MAKES A BRIEF RETURN WED MORNING...THEN SHUNTS EAST AS LOW
PRESSURE DEEPENS IN OK. PRECIP MAY START TO BREAK OUT IN
IOWA/NORTHERN IL DURING THE DAY...BUT NOT THIS FAR NE. IF WE GET
LUCKY...WE COULD SEE SOME BRIEF PERIODS OF SUN AS LOW LEVEL MOISTURE
GETS INCREASINGLY THIN...BUT MID/HIGH CLOUD WILL BE ON THE INCREASE
LATE.
MIN TEMPS ABOVE GUIDANCE GIVEN ABUNDANT CLOUDS...MID 20S TO LOWER
30S. MAX TEMPS MID 30S TO NEAR 40F.
REST OF THE FORECAST...YESTERDAYS TIGHTLY-CLUSTERED SOLUTIONS WERE
DESTINED NOT TO REPEAT. THE DAY SHIFT NOTED A TREND TOWARD A LESS
AMPLIFIED AND MORE SOUTHERLY TRACK FOR THE LOW FORECAST TO CROSS THE
LAKES REGION LATE THURSDAY. TONIGHT...WE/VE MOVED BACK TO A MEAN
THAT LOOKS SIMILAR TO LAST NIGHT...THOUGH WITH MORE IN THE WAY OF
MODEL SPREAD. THEY (AND I) CONTINUE TO STRUGGLE A BIT WITH COMPETING
ELEMENTS. WE HAVE A TON OF ENERGY POURING INTO THE PAC COAST TO PUSH
THINGS ALONG...AND A WEAK BLOCKING RIDGE OVER FAR EASTERN CANADA.
THE BLOCK IS NOT IMPRESSIVE AND WILL BE DISLODGED...BUT HOW QUICKLY?
THE INCOMING UPPER TROF TAKES ON A NEGATIVE TILT...BUT OVERALL THE
PATTERN IS QUITE PROGRESSIVE AND NOT HIGHLY AMPLIFIED. HOW MUCH WILL
THE SYSTEM WRAP UP...SLOW DOWN...AND GET TUGGED NW (IF AT ALL)?
THE NAM AND DGEX REPRESENT DEEPER AND MORE NORTHERLY TRACKS THAT
WOULD BE MORE RAIN AND LESS SNOW FOR US. 00Z ECMWF OFFERS THE MOST
SOUTHERLY...SNOWIEST SOLUTION. GFS/GEM ARE SOMEWHERE IN BETWEEN...
THOUGH WITH THE GEM SLOWER THAN THE REST OF THE MODELS. SOME SORT OF
GEM/GFS/ECMWF MISH-MASH IS MOST APPROPRIATE...AS WE STILL HAVE TIME
TO SEE HOW THE DETAILS FALL OUT.
PRECIP SHOULD ARRIVE IN SW SECTIONS OVERNIGHT WED NIGHT...MAINLY AS
SNOW. A TRACK ACROSS CENTRAL LOWER MI LATE THURSDAY WILL OPEN UP AT
LEAST THE SE HALF OF THE FORECAST AREA TO MIX WITH/TURN TO RAIN.
WINDY/SNOWY CONDITIONS LATE THURSDAY NIGHT INTO FRIDAY AS SYSTEM
DEPARTS. POTENTIAL FOR SUBSTANTIAL LAKE ENHANCEMENT...BUT VERY
DIFFICULT TO ANSWER THE FETCH QUESTION YET GIVEN MODEL DIFFS. WILL
TRY TO ADD A FEW DETAILS TO THE HAZ WX OUTLOOK. COLDER TEMPS (NEAR
CLIMO) OVER THE WEEKEND...WITH DECREASING CHANCES FOR LAKE EFFECT AS
SURFACE RIDGING TRIES TO EDGE EAST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 633 AM EST MON DEC 17 2012
MVFR CIGS WILL REMAIN OVER ALL TAF SITES THROUGH THE TAF
PERIOD...AS SLIGHTLY DRIER AIR MOVES IN AND SURFACE LOW MOVES INTO
ONTARIO AND WEAKENS. LITTLE TO NO CHANCE THAT THE CLOUD DECK WILL
SCOUR OUT TONIGHT WITH MFVR CLOUDS EXTENDING ALL THROUGH THE
WESTERN GREAT LAKES INTO THE NORTHERN PLAINS...WITH WEAK WINDS AND
NO SIGNIFICANT AIR MASS CHANGE FURTHER HELPING TO KEEP CLOUDS IN
PLACE. WE WILL SEE SOME NUISANCE LAKE EFFECT -SHRA OR -SHSN
ACROSS APN/PLN/TVC TODAY...BUT NOTHING THAT WILL CREATE PROBLEMS
IN TERMS OF RESTRICTING VSBY`S.
&&
.MARINE...
ISSUED AT 315 AM EST MON DEC 17 2012
LIGHT WINDS AND LOW WAVES ARE EXPECTED AS WE HEAD INTO THE MID WEEK
PERIOD...AS WEAK LOW PRESSURE DRIFTS OUT OF THE REGION TODAY...ONLY
TO BE REPLACED BY HIGH PRESSURE THROUGH AT LEAST WEDNESDAY EVENING.
THE ONE EXCEPTION WILL BE TODAY...AS SLIGHTLY STRONGER WINDS WILL BE
FOUND ACROSS THE WATERS (STILL LESS THAN 20 KNOTS) AS COOLER AIR
FILTERS INTO THE REGION. AFTER THAT...STRONG LOW PRESSURE IS
EXPECTED TO TRACK THROUGH THE REGION WEDNESDAY NIGHT THROUGH
FRIDAY...USHERING IN A PERIOD OF MUCH STRONGER WINDS...WITH GALE
FORCE GUSTS VERY POSSIBLE. WIDESPREAD RAIN AND/OR SNOW IS ALSO
EXPECTED TO ACCOMPANY THIS SYSTEM...WITH LAKE EFFECT SNOW SHOWERS
AND CONTINUED GUSTY CONDITIONS LIKELY FOR THE WEEKEND.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MB
SYNOPSIS...JZ
SHORT TERM...LAWRENCE
LONG TERM...JZ
AVIATION...NS
MARINE...LAWRENCE
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1149 AM CST MON DEC 17 2012
.UPDATE...
ISSUED AT 1148 AM CST MON DEC 17 2012
BAND OF SNOW HAS BEEN DECREASING IN AREAL COVERAGE AND INTENSITY THE
PAST HOUR WHICH IS IN LINE WITH THE RECENT RUNS OF THE RAP WHICH
DEPICTS THE MID LEVEL FRONTOGENESIS QUICKLY DIMINISHING. HAVE HAD
REPORTS OF 1-2 INCH ACCUMULATIONS WITHIN THE BAND THIS MORNING. WILL
STILL SEE SOME WEAK ASCENT THROUGH THE AFTERNOON AHEAD OF UPPER
TROUGH WHICH BACK IN WESTERN MISSOURI...SO WILL STILL HAVE SOME
AREAS OF -RA OR -RASN THROUGH THE AFTERNOON.
ISSUED AT 928 AM CST MON DEC 17 2012
HAVE BEEN GETTING REPORTS OF SOME LIGHT SNOW ACCUMULATION WITHIN
THE PRECIPITATION BAND THAT CURRENTLY EXTENDS FROM MEXICO TO
PITTSFIELD. THIS IS COINCIDENT WITH A BAND OF MID-LEVEL FRONTOGENESIS
DEPICTED BY THE RAP THAT WILL SINK SOUTH AND DECREASE IN INTENSITY.
FOR NOW HAVE ADDED WINTRY MIX WORDING TO THE NORTHERN THIRD OF THE
CWA WITH SOME MINOR SNOW ACCUMULATIONS. HAVE STUCK WITH JUST RAIN
IN THE FORECAST THIS AFTERNOON AS RAP SOUNDINGS ARE SHOWING A
SLIGHTLY WARMER BOUNDARY LAYER. ALSO LOWERED TEMPERATURES OVER THE
NORTHERN PART OF THE CWA TODAY GIVEN THE PRECIPITATION AND CLOUDS.
BRITT
&&
.SHORT TERM...
ISSUED AT 322 AM CST MON DEC 17 2012
(TODAY THROUGH TUESDAY NIGHT)
THE COLD FRONT WHICH PASSED SOUTH OF OUR AREA YESTERDAY HAS STALLED
OVER NORTHEAST ARKANSAS...THE MISSOURI BOOT HEEL AND EXTREME
SOUTHERN ILLINOIS THIS MORNING. ALOFT...A DEEPENING SHORTWAVE IS
MOVING EAST FROM THE GREAT PLAINS INTO WESTERN MISSOURI. THE
SHORTWAVE WILL CONTINUE MOVING EAST TODAY AND INTERACT WITH A
RELATIVELY SHALLOW LAYER OF LOW LEVEL MOISTURE. RADAR OVER
SOUTHEAST KANSAS SHOWS A COUPLE OF BANDS OF LIGHT RAIN MOVING EAST
NORTHEAST. EXPECT THESE BANDS TO CONTINUE MOVING EAST WITH THE
SHORTWAVE TODAY...PERHAPS EXPANDING IN AREAL COVERAGE AS THE WAVE
ENCOUNTERS THE SOMEWHAT DEEPER MOISTURE IN PLACE OVER OUR AREA.
HAVE INCREASED POPS A BIT TO SHOW THIS...HOWEVER...ANY PRECIP THAT
DOES FALL SHOULD BE VERY LIGHT AND MAY NOT MEASURE. TEMPS SHOULD BE
COOLER TODAY ACROSS THE SOUTHERN 1/2 OF THE CWFA BEHIND THE
FRONT...ESPECIALLY IF THERE`S PRECIP IN THE AREA. TEMPS BEHIND THE
FRONT YESTERDAY WERE GENERALLY IN THE LOW TO MID 40S...SO GUIDANCE
TEMPS LOOKED PRETTY REASONABLE.
UPPER LEVEL RIDGE BUILDS OVER THE REGION LATE TONIGHT INTO TUESDAY
WHICH DIVERTS ANOTHER SHORTWAVE TO OUR NORTH. HOWEVER...THE WAVE
TURNS OUR LOW LEVEL FLOW BACK AROUND TO THE SOUTHWEST WHICH QUICKLY
BRINGS WARMER AIR BACK INTO THE MID-MISSISSIPPI VALLEY. FORECAST
SOUNDINGS ARE INDICATING A RELATIVELY CLOUD-FREE DAY AS WELL UNDER
THE UPPER RIDGE...SO EXPECT WARMING BACK INTO THE 50S...NEAR 60 IN
CENTRAL MO. WILL SEE INCREASING HIGH CLOUDS TUESDAY NIGHT AHEAD OF
THE NEXT STORM SYSTEM...THAT AND PERSISTENT SOUTHERLY FLOW OVER MUCH
OF THE AREA SHOULD KEEP TEMPS RELATIVELY MILD IN THE MID TO UPPER
30S.
CARNEY
&&
.LONG TERM...
ISSUED AT 322 AM CST MON DEC 17 2012
(WEDNESDAY THROUGH SUNDAY)
PRIMARY FOCUS CONTINUES TO BE STRONG STORM DEVELOPING WEDNESDAY OVER
THE PLAINS AND MOVING INTO THE MIDWEST WEDNESDAY NIGHT. MODEL
SOLUTIONS ARE...IF ANYTHING...LESS CERTAIN THAN THEY WERE
YESTERDAY. EACH ONE SEEMS TO HAVE A DIFFERENT TRACK FOR THE STORM.
NAM...GFS...AND GEM TAKE THE SURFACE AND 850MB LOW WELL NORTH OF ST.
LOUIS...WHILE THE ECMWF MOVES THE LOW ALMOST DIRECTLY OVER THE METRO
AREA...AND IS ABOUT 6HRS SLOWER IN ITS EASTWARD PROGRESSION OF THE
STORM THAN THE OTHER MODELS. OBVIOUSLY THE SLOWER/MORE SOUTHERN
ECMWF IS MORE FAVORABLE FOR SNOW IN NORTHERN PORTIONS OF THE CWFA.
IT`S ALSO MORE CONSISTENT WITH PREVIOUS MODEL RUNS...SO HAVE LEANED
IN THIS DIRECTION. IF YOU BELIEVE THE ECMWF VERBATIM...RAIN AND
THUNDERSTORMS WILL BE THE RULE ACROSS THE ENTIRE AREA AT LEAST
THROUGH MIDNIGHT...PROBABLY UNTIL SOMETIME BETWEEN 09Z AND 12Z
THURSDAY MORNING. SHOULD SEE PRECIP CHANGE OVER RAPIDLY ACROSS THE
AREA FROM 12Z THROUGH 18Z THURSDAY AS COLD AIR WRAPS AROUND THE
LOW. THE VAST MAJORITY OF THE AREA PROBABLY WON`T EVEN SEE A
DUSTING IN THIS SCENARIO...HOWEVER PARTS OF NORTHEAST MISSOURI AND
WEST CENTRAL ILLINOIS COULD SEE SOME LIGHT ACCUMULATIONS. THE OTHER
BIG IMPACT OF THIS STORM LOOKS TO BE WIND. FORECAST SOUNDINGS ARE
SHOWING WIND GUSTS IN EXCESS OF 35KTS. WILL HAVE TO KEEP AN EYE ON
THIS FOR A POTENTIAL WIND ADVISORY.
REMAINDER OF THE FORECAST LOOKS PRETTY QUIET WITH QUASI-ZONAL FLOW
ALOFT BEHIND THE STORM. LOOKS LIKE TEMPERATURES WILL BE SEASONABLY
COOL FOR FRIDAY AND SATURDAY...WITH COOLING TEMPS ON SUNDAY AS THE
FLOW AMPLIFIES WITH LOW PRESSURE OVER THE EAST COAST PUSHING COLD
CANADIAN AIR SOUTH THROUGH THE MISSISSIPPI VALLEY.
CARNEY
&&
.AVIATION...
ISSUED AT 1148 AM CST MON DEC 17 2012
IFR/MVFR CIGS/VSBYS ARE STILL ACROSS MUCH OF MO/IL AT THIS HOUR.
EXPECT ONLY SLOW IMPROVEMENT IN CIGS TODAY BEFORE GOING VFR
TONIGHT. HAVE INCLUDED -RA OR VCSH IN THE FIRST 1-3 HOURS AHEAD OF
AN UPPER LEVEL DISTURBANCE IN WESTERN MISSOURI. WINDS WILL
GENERALLY BE LIGHT...BUT SHOULD THEN INCREASE OUT OF THE
SOUTHWEST BY MID MORNING TUESDAY.
SPECIFICS FOR KSTL...EXPECT -DZ OR PATCHY -RA TO AFFECT THE TERMINAL
EARLY IN THE PERIOD...BUT THEN EXPECT SLOW IMPROVEMENT IN THE CIGS/VSBYS
LATER THIS AFTERNOON AND TONIGHT. LIGHT WINDS WILL BACK ROM
NORTHWEST TO WEST THROUGH THIS EVENING BEFORE INCREASING OUT OF
THE SOUTHWEST BY MID MORNING TUESDAY.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
933 AM CST MON DEC 17 2012
.UPDATE...
ISSUED AT 928 AM CST MON DEC 17 2012
HAVE BEEN GETTING REPORTS OF SOME LIGHT SNOW ACCUMULATION WITHIN
THE PRECIPITATION BAND THAT CURRENTLY EXTENDS FROM MEXICO TO
PITTSFIELD. THIS IS COINCIDENT WITH A BAND OF MID-LEVEL FRONTOGENESIS
DEPICTED BY THE RAP THAT WILL SINK SOUTH AND DECREASE IN INTENSITY.
FOR NOW HAVE ADDED WINTRY MIX WORDING TO THE NORTHERN THIRD OF THE
CWA WITH SOME MINOR SNOW ACCUMULATIONS. HAVE STUCK WITH JUST RAIN
IN THE FORECAST THIS AFTERNOON AS RAP SOUNDINGS ARE SHOWING A
SLIGHTLY WARMER BOUNDARY LAYER. ALSO LOWERED TEMPERATURES OVER THE
NORTHERN PART OF THE CWA TODAY GIVEN THE PRECIPITATION AND CLOUDS.
BRITT
&&
.SHORT TERM...
ISSUED AT 322 AM CST MON DEC 17 2012
(TODAY THROUGH TUESDAY NIGHT)
THE COLD FRONT WHICH PASSED SOUTH OF OUR AREA YESTERDAY HAS STALLED
OVER NORTHEAST ARKANSAS...THE MISSOURI BOOT HEEL AND EXTREME
SOUTHERN ILLINOIS THIS MORNING. ALOFT...A DEEPENING SHORTWAVE IS
MOVING EAST FROM THE GREAT PLAINS INTO WESTERN MISSOURI. THE
SHORTWAVE WILL CONTINUE MOVING EAST TODAY AND INTERACT WITH A
RELATIVELY SHALLOW LAYER OF LOW LEVEL MOISTURE. RADAR OVER
SOUTHEAST KANSAS SHOWS A COUPLE OF BANDS OF LIGHT RAIN MOVING EAST
NORTHEAST. EXPECT THESE BANDS TO CONTINUE MOVING EAST WITH THE
SHORTWAVE TODAY...PERHAPS EXPANDING IN AREAL COVERAGE AS THE WAVE
ENCOUNTERS THE SOMEWHAT DEEPER MOISTURE IN PLACE OVER OUR AREA.
HAVE INCREASED POPS A BIT TO SHOW THIS...HOWEVER...ANY PRECIP THAT
DOES FALL SHOULD BE VERY LIGHT AND MAY NOT MEASURE. TEMPS SHOULD BE
COOLER TODAY ACROSS THE SOUTHERN 1/2 OF THE CWFA BEHIND THE
FRONT...ESPECIALLY IF THERE`S PRECIP IN THE AREA. TEMPS BEHIND THE
FRONT YESTERDAY WERE GENERALLY IN THE LOW TO MID 40S...SO GUIDANCE
TEMPS LOOKED PRETTY REASONABLE.
UPPER LEVEL RIDGE BUILDS OVER THE REGION LATE TONIGHT INTO TUESDAY
WHICH DIVERTS ANOTHER SHORTWAVE TO OUR NORTH. HOWEVER...THE WAVE
TURNS OUR LOW LEVEL FLOW BACK AROUND TO THE SOUTHWEST WHICH QUICKLY
BRINGS WARMER AIR BACK INTO THE MID-MISSISSIPPI VALLEY. FORECAST
SOUNDINGS ARE INDICATING A RELATIVELY CLOUD-FREE DAY AS WELL UNDER
THE UPPER RIDGE...SO EXPECT WARMING BACK INTO THE 50S...NEAR 60 IN
CENTRAL MO. WILL SEE INCREASING HIGH CLOUDS TUESDAY NIGHT AHEAD OF
THE NEXT STORM SYSTEM...THAT AND PERSISTENT SOUTHERLY FLOW OVER MUCH
OF THE AREA SHOULD KEEP TEMPS RELATIVELY MILD IN THE MID TO UPPER
30S.
CARNEY
&&
.LONG TERM...
ISSUED AT 322 AM CST MON DEC 17 2012
(WEDNESDAY THROUGH SUNDAY)
PRIMARY FOCUS CONTINUES TO BE STRONG STORM DEVELOPING WEDNESDAY OVER
THE PLAINS AND MOVING INTO THE MIDWEST WEDNESDAY NIGHT. MODEL
SOLUTIONS ARE...IF ANYTHING...LESS CERTAIN THAN THEY WERE
YESTERDAY. EACH ONE SEEMS TO HAVE A DIFFERENT TRACK FOR THE STORM.
NAM...GFS...AND GEM TAKE THE SURFACE AND 850MB LOW WELL NORTH OF ST.
LOUIS...WHILE THE ECMWF MOVES THE LOW ALMOST DIRECTLY OVER THE METRO
AREA...AND IS ABOUT 6HRS SLOWER IN ITS EASTWARD PROGRESSION OF THE
STORM THAN THE OTHER MODELS. OBVIOUSLY THE SLOWER/MORE SOUTHERN
ECMWF IS MORE FAVORABLE FOR SNOW IN NORTHERN PORTIONS OF THE CWFA.
IT`S ALSO MORE CONSISTENT WITH PREVIOUS MODEL RUNS...SO HAVE LEANED
IN THIS DIRECTION. IF YOU BELIEVE THE ECMWF VERBATIM...RAIN AND
THUNDERSTORMS WILL BE THE RULE ACROSS THE ENTIRE AREA AT LEAST
THROUGH MIDNIGHT...PROBABLY UNTIL SOMETIME BETWEEN 09Z AND 12Z
THURSDAY MORNING. SHOULD SEE PRECIP CHANGE OVER RAPIDLY ACROSS THE
AREA FROM 12Z THROUGH 18Z THURSDAY AS COLD AIR WRAPS AROUND THE
LOW. THE VAST MAJORITY OF THE AREA PROBABLY WON`T EVEN SEE A
DUSTING IN THIS SCENARIO...HOWEVER PARTS OF NORTHEAST MISSOURI AND
WEST CENTRAL ILLINOIS COULD SEE SOME LIGHT ACCUMULATIONS. THE OTHER
BIG IMPACT OF THIS STORM LOOKS TO BE WIND. FORECAST SOUNDINGS ARE
SHOWING WIND GUSTS IN EXCESS OF 35KTS. WILL HAVE TO KEEP AN EYE ON
THIS FOR A POTENTIAL WIND ADVISORY.
REMAINDER OF THE FORECAST LOOKS PRETTY QUIET WITH QUASI-ZONAL FLOW
ALOFT BEHIND THE STORM. LOOKS LIKE TEMPERATURES WILL BE SEASONABLY
COOL FOR FRIDAY AND SATURDAY...WITH COOLING TEMPS ON SUNDAY AS THE
FLOW AMPLIFIES WITH LOW PRESSURE OVER THE EAST COAST PUSHING COLD
CANADIAN AIR SOUTH THROUGH THE MISSISSIPPI VALLEY.
CARNEY
&&
.AVIATION...
ISSUED AT 513 AM CST MON DEC 17 2012
LOW PRESSURE MOVING ALONG A STALLED FRONTAL BOUNDARY TO OUR SOUTH
WILL INSURE IFR CONDITIONS AND SCATTERED SHOWERS THIS MORNING
ALONG AND SOUTH OF I-7O. CEILING AND VISIBILITY TO RISE BACK TO
MVFR CONDITIONS LATER THIS AFTERNOON FROM WEST TO EAST AS THE WEAK
STORM SYSTEM EXITS TO THE EAST. STRATUS WILL EVENTUALLY LIFT NORTH
AND EAST OF THE CWA TONIGHT LOW LEVEL FLOW BECOMES SOUTHERLY.
SPECIFICS FOR KSTL...
IFR CONDITIONS ARE EXPECTED THIS MORNING WITH SCATTERED SHOWERS AS
AREA OF LOW PRESSURE PASSES TO THE SOUTHEAST OF THE TERMINAL. WIND
TO VEER FROM NORTH TO NORTHWEST TODAY AND EVENTUALLY TO THE SOUTH
TONIGHT. STRATUS WILL BE SLOW TO CLEAR UNTIL WIND BECOMES
SOUTHERLY AND ADVECTS IT TO THE NORTHEAST. HAVE THEREFORE PUSHED
CLEARING TO LATE TONIGHT.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
349 PM CST MON DEC 17 2012
.DISCUSSION...
THE STORM OF INTEREST IS RAPIDLY APPROACHING THE PACIFIC NORTHWEST COAST.
MODELS AND TIMING TOOLS INDICATE THE DISTURBANCE IS MOVING EAST
SOUTHEAST AT 30KTS AND WILL CONTINUE SO THROUGH WEDNESDAY NIGHT.
SOME MODEL SOLNS ARE SOUTH...NORTH...WETTER AND DRIER. THE ECMWF
HAS BEEN THE MOST CONSISTENT FOCUSING THE BEST FORCING ACROSS SWRN
NEB SOUTH OF INTERSTATE 80. THE GFS...NAM AND GEM HAVE BEEN
WOBBLING NORTH AND SOUTH. THE ECM IS ALSO ABOUT 6 HOURS SLOWER
THAN THE OTHER MODELS AND SHOWS THE DRIEST BOUNDARY LAYER MOISTURE
AND PRODUCES THE LEAST QPF. THE GFS ENSEMBLE H700MB LOW TRACK AND
QPF IS A REASONABLE COMPROMISE IN TERMS OF TIMING AND CAPTURING
AREAS SOUTH OF NEBRASKA HIGHWAY 2 WITH SNOW.
THE FEATURE OF INTEREST APPEARS TO BE VERY STRONG BUT FAST MOVING
MID LEVEL FRONTOGENESIS AND DEFORMATION ALONG AND JUST NORTH OF
THE H700MB LOW. IT IS STRONGLY TILTED POSITIVELY. THIS SHOULD
PRODUCE A RELATIVELY NARROW BAND OF LIGHT TO MODERATE SNOW. THE
NAM IS SHOWING HEAVY SNOW AS TEMPERATURES ARE VERY FAVORABLE FOR
GROWTH AND THE DENDRITIC LAYER WILL BE DESCENDING AS COLD AIR
FILLS IN BEHIND THE H7 LOW. THE QUICK MOTION OF THE STORM MAKES
HEAVY SNOW LESS LIKELY.
ONE THING ALL MODELS AGREE ON ARE WIND SPEEDS. A NRN STREAM
DISTURBANCE MOVING THROUGH THE NRN PLAINS TUESDAY WILL TAP SOME
ARCTIC AIR AND THIS WILL DROP SOUTH WEDNESDAY MORNING AND GET
CAUGHT UP IN THE SFC CYCLONE. WIND SPEEDS WEDNESDAY AFTN SHOULD
INCREASE TO 15 TO 25 MPH WITH SPEEDS APPROACHING 30 MPH ACROSS FAR
SWRN NEB. MOST OF THE SNOW SHOULD BE OVER BY TIME THE WINDS COME
UP BUT THATS PERFECT FOR BLOWING SNOW.
THURSDAY THROUGH SATURDAY...A ZONAL FLOW TAKES OVER ALOFT PRODUCING
CLEAR SKIES A GRADUAL MODERATION IN TEMPERATURES. THE WEATHER MAY
BE QUIET IN NEBRASKA BUT A LARGE UPPER LEVEL RIDGE WILL BUILD
ACROSS ALASKA SUPPORTING THE DEVELOPMENT OF A VERY LARGE ARCTIC
HIGH PRESSURE SYSTEM. THIS HIGH WILL EVENTUALLY DROP SOUTH AND THE
MODELS ARE HAVING TROUBLE TIMING THE EVENTUAL ARCTIC FRONTAL
PASSAGE INTO NEBRASKA. TODAYS MODEL RUNS SUGGEST THE FRONT WILL
DROP IN MONDAY...A DAY OR SO LATER THAN YESTERDAYS MODEL SOLNS. SO
THERE IS A CHANCE OF SNOW MONDAY FOR UPSLOPE CONDITIONS.
OTHERWISE THE FCST IS STRAIGHT FORWARD. THE ARCTIC DRAPE ACROSS
NORTHEAST NEBRASKA WHILL REMAIN IN PLACE TONIGHT THROUGH 14Z
TUESDAY ACCORDING TO THE RUC. SFC LOW PRESSURE WILL DROP SOUTHEAST
ALONG THE FRONT TONIGHT. IT MAY EVEN REMAIN ON TUESDAY BUT THATS
NOT INDICATED BY ANY MODEL. THE TANDEM EFFECT OF THE NRN STREAM
LOW AND THE LOW DROPPING THROUGH NEB TONIGHT SHOULD LIFT THE
ARCTIC FRONT AND CLOUDS NORTH TUESDAY.
&&
.AVIATION...
VISUAL FLIGHT RULES FOR TERMINALS KLBF AND KVTN THROUGH 18/18Z
TUESDAY. SHORT TERM MODELS DIFFER IN AVAILABLE MOISTURE PROFILES
WHERE A BLEND OF THE RUC AND GFS WERE USED THROUGH THE PERIOD. THE
LOW STRATUS AND FOG TO THE EAST OF KVTN WILL CONTINUE TO MOVE SLOWLY
EAST WHILE WEAK RIDGING ALOFT IN THE WEST BREAKS DOWN FOR INCREASING
ZONAL FLOW OVERNIGHT. CLOUD HEIGHTS AOB 7 KFT WITH CEILINGS RANGING
BETWEEN 7 KFT TO 15 KFT THROUGH EVENING. THEN CLEARING OVERNIGHT
THROUGH 18Z TUESDAY.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1128 AM CST MON DEC 17 2012
.AVIATION...18Z TAF. LIFR CIGS REMAIN ON THE NORTH AND EASTERN
PERIPHERIES OF THE TERMINAL LATE THIS MORNING...AND THE LOW CLOUD
DECK IS EXPECTED TO GRADUALLY MOVE EASTWARD DURING THE AFTERNOON.
A SURFACE TROUGH ALONG THE EASTERN SLOPES OF THE ROCKIES WILL
SLIDE EAST TODAY AND WINDS WILL BE FAIRLY LIGHT AND VARIABLE FOR A
FEW HOURS BEFORE SHIFTING SOUTHWEST AND SOUTHERLY UNTIL EARLY
EVENING. AS THE TROUGH MOVES THRU TONIGHT...WINDS WILL SHIFT
WESTERLY BEHIND THE SYSTEM.
&&
PREV DISCUSSION... /ISSUED 516 AM CST MON DEC 17 2012/
SHORT TERM...THROUGH WEDNESDAY NIGHT. THE PRIMARY CONCERN DURING
THE NEXT 72 HOURS CONTINUES TO BE STILL APPEARS TO BE OUR FIRST
WIDESPREAD ACCUMULATING SNOW/BLOWING SNOW EVENT OF THE SEASON WED
INTO WED NIGHT. OVERALL LITTLE HAS CHANGED IN PREVIOUS
THINKING...AS CONFIDENCE IS FAIRLY HIGH THAT HEADLINE-WORTHY
CONDITIONS FEATURING AT LEAST A FEW INCHES OF SNOW AND PLENTY OF
WIND BE REALIZED FOR MOST IF NOT ALL OF THE AREA...BUT THE DETAILS
REGARDING TOTAL ACCUMULATION POTENTIAL ARE STILL UNCERTAIN...AND
CAUTION IS ADVISED AGAINST TAKING THE CURRENT SNOWFALL FORECAST
TOO LITERALLY JUST YET AS THE SYSTEM IS STILL WELL OUT OVER THE
PACIFIC.
STARTING OFF AT 09Z THIS MORNING...THERE ARE A FEW PESKY ISSUES TO
CONSIDER WELL BEFORE THE WED STORM ARRIVES. OBJECTIVE SURFACE
ANALYSIS FEATURES A WEAKISH 1007MB LOW OVER THE FAR NORTHERN
CWA...WITH A VERY SUBTLE TROUGH AXIS TRAILING SOUTH NEAR THE
HIGHWAY 281 CORRIDOR...DOING LITTLE MORE THAN SEPARATING A LIGHT
BUT STEADY WESTERLY BREEZE IN WESTERN COUNTIES...FROM SLIGHTLY
MORE SOUTHERLY LIGHT BREEZES IN THE EAST. TEMPS EARLY THIS
MORNING HAVE TRENDED A FEW DEGREES WARMER THAN EARLIER
FORECAST...WITH LOWS LIKELY ENDING UP IN THE MID 20S MOST
AREAS...EXCEPT FOR COLDER IN THE TYPICAL DAWSON/VALLEY COUNTIES
CORRIDOR. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA
REVEAL A MODEST MID LEVEL SHORTWAVE TROUGH AXIS TRACKING DIRECTLY
OVER THE CWA AT THIS HOUR...ALTHOUGH WITH THE MAJORITY OF UPWARD
FORCING ALREADY WELL OFF TO THE EAST...SKIES HAVE LARGELY CLEARED
BEHIND THIS UPPER TROUGH AXIS...WHICH ACTUALLY BROUGHT A NARROW
LINE OF LIGHT SLEET SHOWERS TO PRIMARILY THE SOUTHWESTERN 1/4 OF
THE CWA ON SUNDAY EVENING. UNFORTUNATELY...WHAT ORIGINALLY
APPEARED TO BE A FAIRLY STRAIGHTFORWARD SKY COVER FORECAST HAS
BEEN COMPLICATED BY A FAIRLY SOLID PROTRUSION OF VERY LOW STRATUS
THAT IS CURRENTLY SINKING SOUTH ACROSS NORTH CENTRAL
NEBRASKA...AND IS POISED TO OVERTAKE AT LEAST A FEW COUNTIES IN
THE CWA NORTH OF HIGHWAY 92 OVER THE NEXT FEW HOURS. THIS LOW
CLOUD DECK IS ALSO ASSOCIATED WITH AT LEAST PATCHY FOG WITH
VISIBILITY AROUND/UNDER 1 MILE.
FORECAST WISE...THE OBVIOUS VERY SHORT TERM ISSUE TODAY IS THE
AFOREMENTIONED LOW STRATUS JUST NOW MOVING INTO OUR FAR NORTHERN
COUNTIES...AS THIS WAS NOT WELL-ANTICIPATED BY MODELS AT ALL. THE
LATEST RAP RUNS HAVE FINALLY CAUGHT ONTO IT SOMEWHAT PER THE
950-925MB RELATIVE HUMIDITY FIELDS...AND THUS THE GENERAL
EXPECTATION IS THAT THIS STRATUS AND ASSOCIATED FOG WILL IN FACT
INVADE ROUGHLY THE 5 NORTHEASTERN-MOST COUNTIES SUCH AS
NANCE/GREELEY OVER THE NEXT FEW HOURS...AND POSSIBLY HANG AROUND
WELL INTO THE DAYLIGHT HOURS BEFORE FINALLY PUSHING OUT TO THE
NORTHEAST BY EARLY-MID AFTERNOON. ALTHOUGH THIS STRATUS IS
CURRENTLY NOT EXPECTED TO SINK AS FAR SOUTHWEST AS GRAND
ISLAND/HASTINGS...THIS WILL BEAR WATCHING AS IT COULD GET SOMEWHAT
CLOSE. ALTHOUGH AM CURRENTLY NOT AWARE OF ANY DENSE FOG ASSOCIATED
WITH THIS STRATUS DECK...CURRENTLY HAVE PATCHY FOG IN THE GRIDS
THROUGH 15Z IN BOTH THE NORTHEASTERN AND FAR SOUTHERN CWA...WITH
THE LATTER ASSOCIATED WITH A COMPLETELY SEPARATE AREA OF LOW
STRATUS BARELY SKIRTING SOUTH OF THE AREA ACROSS CENTRAL KS.
MOVING ON TO OTHER ELEMENTS OF TODAY/S FORECAST...THOSE AREAS THAT
DON/T GET SOCKED IN SHOULD REALIZE QUITE A BIT OF SUNSHINE
TODAY...ALTHOUGH AT LEAST THIN MID/HIGH CLOUDS WILL BE ON THE
INCREASE FROM THE WEST THIS AFTERNOON AHEAD OF THE NEXT VERY
SUBTLE MID LEVEL WAVE. AT THE SURFACE...LOW PRESSURE DEVELOPING
ALONG AN AXIS FROM MT TO NORTHWEST NEB TODAY WILL GRADUALLY TURN
BREEZES MORE SOUTHERLY...WITH SUSTAINED SPEEDS AT LEAST 10-15 MPH
IN MOST AREAS WITH SOME HIGHER GUSTS. RAISED HIGHS TEMPS 1-3
DEGREES FROM PREVIOUS FORECAST IN SOME AREAS...BUT OVERALL SIMILAR
TO PREVIOUS WITH MOST NEB ZONES MID-UPPER 40S AND KS ZONES MAINLY
LOW-MID 50S.
TONIGHT...THE NEXT MID LEVEL SHORTWAVE TROUGH WILL TRACK PRIMARILY
ACROSS THE NORTHERN 1/2 OF NEB...WITH ISENTROPIC LIFT AHEAD OF
THIS WAVE POSSIBLY SPARKING SOME FLURRIES OR LIGHT ACCUMULATING
SNOW WITHIN 100 MILES OR SO NORTH/NORTHEAST OF THE CWA...BUT AM
NOT FORECASTING ANY SNOW TO AFFECT OUR LOCAL AREA AT THIS TIME. A
SURFACE LOW ASSOCIATED WITH THIS WAVE WILL TRACK ACROSS NORTHERN
NEB THROUGH THE NIGHT...SIMILAR TO THE ONE THIS MORNING EXCEPT
STRONGER. THIS WILL INDUCE A NOTICEABLY WESTERLY BREEZE
OVERNIGHT...WITH SUSTAINED SPEEDS LIKELY NEAR OR EXCEEDING 15 MPH
FOR AT LEAST A FEW HOURS. DESPITE MOSTLY CLEAR SKIES...THESE WEST
WINDS SHOULD HELP HOLD TEMPS UP FAIRLY EFFICIENTLY. MADE LITTLE
CHANGE TO LOW TEMPS...KEEPING THEM PRIMARILY MID 20S...BUT WOULD
NOT BE SURPRISED TO SEE SOME AREAS HOLD UP CLOSER TO 30.
TUESDAY LOOKS TO BE A FAIRLY TRANQUIL/MILD DAY AHEAD OF THE
APPROACHING PRIMARY STORM SYSTEM...WHICH WILL FINALLY BE COMING
ONSHORE IN SOUTHERN CAL. MEANWHILE...SUBTLE SHORTWAVE RIDING WILL
DOMINATE THE CENTRAL PLAINS ALOFT...WHILE AT THE
SURFACE...FAIRLY LIGHT BUT STEADY WESTERLY BREEZES WILL PREVAIL IN
THE WAKE OF THE LOW DEPARTING EAST TOWARD THE LOWER GREAT LAKES.
MADE VERY LITTLE CHANGE TO HIGHS...AS THIS SHOULD BE THE MILDEST
DAY OF THE WEEK IN MOST AREAS AND AM AIMING FOR UPPER 40S
NORTH/NEAR 50 TRI-CITIES AND MID-UPPER 50S KS ZONES.
TUES NIGHT...IT REMAIN PRECIP FREE ACROSS THE CWA...ALTHOUGH
CHANGES WILL GET UNDERWAY AS EAST-NORTHEAST SURFACE WINDS RAMP UP
TO 15+ MPH AS THE NIGHT GOES ON...IN RESPONSE TO CYCLOGENESIS
TAKING PLACE IN THE SOUTHEAST CO/OK PANHANDLE AREA. ALOFT...THERE
IS GOOD MODEL CONSENSUS AMONGST THE NAM/GFS/ECMWF THAT THE
POWERFUL SHORTWAVE AXIS WILL BE NEAR THE 4-CORNERS AT 12Z WED
MORNING. FOR LOW TEMPS...ALMOST NO CHANGE WITH UPPER 20S/LOW 30S.
LAST BUT CERTAINLY NOT LEAST...THE WEDNESDAY INTO WED NIGHT
PERIODS PROMISE TO BE QUITE ACTIVE...BUT AS STATED AT THE
TOP...THE DETAILS REGARDING SNOW ACCUMULATIONS ARE STILL A BIT
SKETCHY. IN SHORT...MODEL CONSENSUS ON THE TRACK OF THE UPPER WAVE
IS PRETTY DECENT...AS IT MIGRATES FROM THE 4-CORNERS REGION AT
SUNRISE WEDNESDAY...TO OVER THE HEART OF NEB/KS EARLY WED
EVENING...TO SOMEWHERE OVER IA/MO BY SUNRISE THURS MORNING. THE
NAM HAS BEEN A BIT OF AN OUTLIER VERSUS OTHER MODELS IN
INTENSIFYING/CLOSING OFF THE 500MB CIRCULATION DIRECTLY OVER THE
CWA AS THE WAVE PASSES...WHICH IN TURN RESULTS IN SOME FAIRLY
CONCERNING MODEL-GENERATED SNOW AMOUNTS IN EXCESS OF 6 INCHES
MAINLY NORTH OF I-80. HOWEVER...BOTH THE GFS/ECMWF MAINTAIN A BIT
MORE SOUTHERN TRACK OF THE SYSTEM...TAKING THE PRIMARY SURFACE LOW
GENERALLY ACROSS THE OK/KS BORDER INTO CENTRAL MO...VERSUS THE NAM
WHICH TAKES THE SURFACE LOW MORE OVER THE KC METRO AREA. THIS
TRACK WILL OBVIOUSLY PROVE CRITICAL AS TO WHETHER THE NORTHERN 1/2
OR SOUTHERN 1/2 OF THE CWA WILL REALIZE THE MOST SNOW...AND FOR
NOW HAVE GENERALLY USED A BLEND OF MODEL SOLUTIONS FOR THIS
MORNING/S FORECAST...WHICH RESULTS IN A VERY ROUGH STORM TOTAL
SNOW FORECAST OF 2-4 INCHES CWA-WIDE. CERTAINLY IT IS POSSIBLE
THAT SOME AREAS COULD SEE MORE THAN THIS...BUT UNTIL THE TRACK
BECOMES A BIT CLEARER IT WOULD NOT BE WISE TO TRY PINPOINTING
HIGHER THAN THIS. ALTHOUGH THIS IS A FAIRLY PROGRESSIVE
SYSTEM...IT WILL HAVE QUITE A BIT GOING FOR IT IN TERMS OF STRONG
UPPER JET DIVERGENCE AND ASSOCIATED MID LEVEL
FRONTOGENESIS/DEFORMATION. TIMING-WISE...THE GENERAL EXPECTATION
IS THAT SNOW WILL FIRST BREAK OUT MAINLY ACROSS THE NORTHWEST 1/3
OF THE CWA/NORTHWEST OF THE TRI-CITIES/DURING THE MORNING
HOURS...AND THEN RAPIDLY EXPAND ACROSS THE REMAINDER OF THE AREA
WED AFTERNOON INTO WED EVENING...WHILE AT THE SAME TIME SUSTAINED
SPEEDS WILL RAMP UP INTO THE 20-30 MPH RANGE WITH GUSTS TO AROUND
40 MPH...FIRST FROM THE NORTHEAST AND THEN SWINGING AROUND TO THE
NORTHWEST BY EVENING. VISIBILITY RESTRICTIONS WILL BE AN ISSUE FOR
SURE...BUT NOT THINKING BLIZZARD CRITERIA OF WIDESPREAD 1/4 MILE
OR LESS AT THIS POINT. LIKELY 60-70 POPS ARE IN PLACE FOR MUCH OF
THE CWA DURING THE AFTERNOON/EVENING HOURS...AND THESE WILL LIKELY
BE RAISED FURTHER OVER THE NEXT FEW DAYS. AFTER
MIDNIGHT...LINGERED SOME 20-30 POPS WITHIN THE EASTERN 1/2 OF THE
CWA...BUT THE VAST MAJORITY OF ACCUMULATIONS SHOULD BE DONE BY
THEN...AND CERTAINLY SHOULD BE OVER WITH WELL BEFORE SUNRISE.
WINDS SHOULD ALSO DIMINISH SOMEWHAT PRIOR TO SUNRISE...RESULTING
IN IMPROVING VISIBILITIES IN ANY BLOWING SNOW. TEMPS ON WED WILL
ESSENTIALLY RISE VERY LITTLE IF ANY FROM OVERNIGHT LOWS...AND KEPT
HIGHS IN THE LOW 30S EXCEPT IN THE FAR SOUTHEAST...WHERE UPPER 30S
COULD BE ATTAINABLE. ALTHOUGH NOT EXPECTING MUCH OF AN ISSUE WITH
SLEET/FREEZING RAIN WITH THIS SYSTEM...WILL HAVE TO WATCH FAR
SOUTHEAST AREAS AROUND BELOIT KS AS THINGS FIRST GET UNDERWAY...AS
TEMPS ALOFT COULD BE JUST WARM ENOUGH FOR A BRIEF WINTRY MIX
BEFORE AN OUTRIGHT CHANGEOVER TO SNOW. FOR NOW THOUGH...HAVE KEPT
ALL MENTION OF MIXED-PHASE OUT OF THE GRIDS.
LONG TERM...STARTING 12Z THURSDAY. GUIDANCE FROM THE
EC...OPERATIONAL GFS AND GEFS-MEAN ALL SUGGEST MID AND UPPER LEVEL
RIDGING WILL PERSIST OVER THE CENTRAL CONUS THROUGHOUT THE LONG
TERM FORECAST PERIOD. THE OVERALL LACK IN KINEMATIC FORCING SHOULD
PRESENT DRY CONDITIONS AS A RESULT. GUIDANCE FROM THE EC AND
OPERATIONAL GFS SUGGEST THE DEPARTING STORM SYSTEM TO OUR EAST
WILL PROVIDE A STIFF NORTHWEST WIND TO OUR AREA THROUGH MUCH OF
THURSDAY. THE INCREASING POTENTIAL FOR FRESH SNOW PACK ACROSS THE
AREA...WORKING IN CONCERT WITH LOW LEVEL COLD AIR
ADVECTION...MEANS TEMPERATURES WILL PROBABLY HAVE DIFFICULTY
CLIMBING ALL THAT FAR ON THURSDAY. GIVEN THIS...WENT AHEAD AND
UNDERCUT ALLBLEND BY 2-3 DEGREES FOR MANY LOCATIONS ACROSS THE CWA
WHICH PRESENTS HIGHS IN THE LOW 30S FOR THE MOST PART. THERE IS A
CHANCE THURSDAY HIGH TEMPERATURES WILL NEED TO BE DECREASED MORE
IN THE COMING DAYS SHOULD THE ANTICIPATED SNOWFALL MATERIALIZE ON
WEDNESDAY. CLEAR SKIES AND A DECREASING LOW LEVEL WIND
FIELD...ALONG WITH A FEW INCHES OF SNOW ON THE GROUND...WILL
LIKELY PRESENT A COLD NIGHT THURSDAY NIGHT. ~30 DEGREE TEMPERATURE
DROP-OFFS DO NOT SEEM UNREASONABLE GIVEN THE EXPECTED SYNOPTIC
SETUP...WHICH WOULD PROVIDE OVERNIGHT LOWS GENERALLY IN THE LOW
TEENS. ALLBLEND ONLY PROVIDE LOWS IN THE MID TO UPPER TEENS AND AS
A RESULT...WENT AHEAD AND UNDERCUT ALLBLEND BY A COUPLE DEGREES
BUT MUCH LIKE THE HIGHS ON THURSDAY...THERE IS A POSSIBILITY THAT
THURSDAY NIGHT LOWS WILL NEED TO BE DECREASED A BIT MORE IN THE
COMING DAYS. A PERSISTENT WESTERLY COMPONENT TO THE LOW LEVEL WIND
FIELD...ALONG WITH MODEST LOW LEVEL WARM AIR ADVECTION...SHOULD
HELP THE SNOW PACK ERODE QUITE A BIT HEADING INTO FRIDAY...WITH A
RESULTANT WARMING TREND EXPECTED. NO REAL REASON TO DISAGREE WITH
ALLBLEND WHICH PRESENTED AFTERNOON HIGHS IN THE 30S AND 40S AND
FRIDAY NIGHT LOWS IN THE MID TO UPPER TEENS. THERE ARE INDICATIONS
FROM THE EC AND OPERATIONAL GFS OF A BACKDOOR COLD FRONT PUSHING
ACROSS THE AREA HEADING INTO THE DAY SATURDAY...WITH ALLBLEND
PRESENTING A SUBTLE COOLING TREND TO FINISH THE LONG TERM FORECAST
PERIOD. NO REASON TO DISAGREE WITH ALLBLEND SO LEFT SUNDAY HIGH
TEMPERATURE IN THE 30S FOR MOST LOCATIONS ACROSS THE CWA.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1126 AM CST MON DEC 17 2012
.AVIATION...
VISUAL FLIGHT RULES FOR TERMINALS KLBF AND KVTN THROUGH 18/18Z
TUESDAY. SHORT TERM MODELS DIFFER IN AVAILABLE MOISTURE PROFILES
WHERE A BLEND OF THE RUC AND GFS WERE USED THROUGH THE PERIOD. THE
LOW STRATUS AND FOG TO THE EAST OF KVTN WILL CONTINUE TO MOVE
SLOWLY EAST WHILE WEAK RIDGING ALOFT IN THE WEST BREAKS DOWN FOR
INCREASING ZONAL FLOW OVERNIGHT. CLOUD HEIGHTS AOB 7 KFT WITH
CEILINGS RANGING BETWEEN 7 KFT TO 15 KFT THROUGH EVENING. THEN
CLEARING OVERNIGHT THROUGH 18Z TUESDAY.
&&
.PREV DISCUSSION... /ISSUED 1105 AM CST MON DEC 17 2012/
UPDATE...
THIS MORNING THE LOW CLOUDS AND AREAS OF FOG ARE SLOWLY LIFTING
AND MOVING EAST ACROSS THE FAR NORTH CENTRAL THIS MORNING. SHORT
TERM MODELS DIFFER IN MOVING THE STRATUS OUT WITH GRIDS AND
FORECAST PRODUCTS UPDATED TOWARD THE RUC SOLUTION. THE ADDITIONAL
CLOUDS AND LIGHT WINDS WILL PRODUCE LESS MIXING WITH AFTERNOON
HIGHS LOWERED ACROSS THE BOARD AS CLOUDS DEVELOP IN THE WEST...AS
SHOWN IN THE CURRENT SATELLITE LOOP.
PREV DISCUSSION... /ISSUED 534 AM CST MON DEC 17 2012/
AVIATION...FOR THE KLBF AND KVTN TERMINALS THROUGH 12Z TUESDAY.
FOR THE KLBF TERMINAL...MID LEVEL CLOUDINESS WILL INCREASE FROM THE
SOUTHWEST LATER THIS MORNING WITH SCATTERED CIGS AOA 10000
FT AGL POSSIBLE AFTER MID MORNING. MID LEVEL CLOUDINESS WILL TRACK
EAST BY MONDAY EVENING WITH CLEAR SKIES EXPECTED THERE AFTER. FOR
THE KVTN TERMINAL...LOW LEVEL CLOUDINESS IS EXPECTED TO REMAIN JUST
TO THE EAST OF THE TERMINAL THIS MORNING...IMPACTING KANW AND KONL
WITH CIGS BLO 1000 FT AGL AND VSBYS DOWN TO A MILE. MID LEVEL
CLOUDINESS WILL INCREASE EARLY THIS AFTERNOON...WITH SCATTERED TO
BROKEN CIGS AON 10000 FT AGL POSSIBLE AFTER 21Z. AT BOTH
TERMINALS...SOUTHWESTERLY WINDS AROUND 10 KTS ARE EXPECTED
TODAY...WITH A SHIFT TO THE WEST AT 10 KTS TONIGHT.
CLB
PREV DISCUSSION... /ISSUED 303 AM CST MON DEC 17 2012/
DISCUSSION...SURFACE LOW PRESSURE WILL DEVELOP FROM NORTHERN WYOMING
TOWARD NORTHWEST NEBRASKA BY THIS AFTERNOON. SOUTH TO SOUTHWEST
WINDS ARE EXPECTED ACROSS THE FORECAST AREA TODAY AHEAD OF THE LOW.
850 MB TEMPERATURES WILL WARM SEVERAL DEGREES OVER THOSE OF
SUNDAY...AND EXPECTING HIGHS TO ALSO BE SEVERAL DEGREES WARMER AS
THAT WARMER AIR ALOFT MIXES TO THE SURFACE. THE ONE EXCEPTION FOR
THE WARMER HIGHS WILL BE ACROSS FAR SOUTHWEST NEBRASKA...WHERE
VISIBLE SATELLITE IMAGERY FROM LATE SUNDAY AFTERNOON STILL REVEALED
A FAIRLY DENSE SNOWPACK. AS THE AFOREMENTIONED SURFACE LOW MOVES
EAST TONIGHT AND TUESDAY...EXPECT A PACIFIC COLD FRONT TO SWEEP
SOUTHEAST ACROSS THE AREA. THIS FRONT WILL BRING A FEW DEGREES OF
COOLING FOR TUESDAY...ESPECIALLY ACROSS NORTH CENTRAL AND NORTHWEST
NEBRASKA.
ALL EYES THEN ON THE SYSTEM POISED TO AFFECT THE AREA WEDNESDAY. THE
GEM...ECMWF...AND GFS ARE ALL FAIRLY SIMILAR WITH THE TRACK OF THE
SYSTEM. THEY DEEPEN A SURFACE LOW BY MIDDAY WEDNESDAY ACROSS THE
TX/OK PANHANDLE REGION...AND THEN TRACK THE LOW EAST ALONG THE KS/OK
BORDER WEDNESDAY AFTERNOON AND NIGHT. IN THE UPPER LEVELS...A LOW
SHOULD TRACK EASTWARD ACROSS OR VERY CLOSE TO SOUTHWEST AND SOUTHERN
NEBRASKA. THE NAM AND SREF CONTINUE TO BE THE FARTHEST NORTH WITH
BOTH THE SURFACE AND UPPER LEVEL LOWS...BUT ARE TRENDING A LITTLE
SOUTH WITH EACH RUN. WILL DISCARD THE NAM/SREF SOLUTIONS AS THEY
CONTINUE TO TREND SLOWLY SOUTH...AND FOCUS MORE ON THE CONSISTENT
ECMWF AND GFS. NATIONAL GUIDANCE ALSO SHIED AWAY FROM THE NAM...AND
INCORPORATED THE LATEST GFS AND ECMWF INTO THEIR PRECIPITATION
FORECAST. THE NATIONAL FORECAST MATCHED CLOSE TO OUR LOCAL
FORECAST...AND HAS AROUND TWO INCHES OF SNOW ACCUMULATION ALONG
I-80...WITH LESS TO THE NORTH AND MORE TO THE SOUTH. NEARLY FOUR
INCHES IS POSSIBLE TOWARD THE NE/KS BORDER. THIS SNOW EVENT WILL
LARGELY BE DRIVEN BY STRONG FRONTOGENESIS...AND WILL NEED TO WATCH
FOR SIGNS OF POSSIBLE BANDING AND HIGHER SNOWFALL AMOUNTS THAN
CURRENTLY FORECASTED.
AFTER THIS EVENT...SEVERAL DAYS OF DRY AND NEAR SEASONABLE
TEMPERATURES ARE EXPECTED. MODELS BEYOND THE FORECAST PERIOD HINTING
AT A POSSIBLE STORM SYSTEM ORGANIZING ON OR AROUND CHRISTMAS. THIS
WILL BE MONITORED VERY CLOSELY THE NEXT FEW DAYS.
TAYLOR
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...99
AVIATION...KECK
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1105 AM CST MON DEC 17 2012
.UPDATE...
THIS MORNING THE LOW CLOUDS AND AREAS OF FOG ARE SLOWLY LIFTING
AND MOVING EAST ACROSS THE FAR NORTH CENTRAL THIS MORNING. SHORT
TERM MODELS DIFFER IN MOVING THE STRATUS OUT WITH GRIDS AND
FORECAST PRODUCTS UPDATED TOWARD THE RUC SOLUTION. THE ADDITIONAL
CLOUDS AND LIGHT WINDS WILL PRODUCE LESS MIXING WITH AFTERNOON
HIGHS LOWERED ACROSS THE BOARD AS CLOUDS DEVELOP IN THE WEST...AS
SHOWN IN THE CURRENT SATELLITE LOOP.
&&
.PREV DISCUSSION... /ISSUED 534 AM CST MON DEC 17 2012/
AVIATION...FOR THE KLBF AND KVTN TERMINALS THROUGH 12Z TUESDAY.
FOR THE KLBF TERMINAL...MID LEVEL CLOUDINESS WILL INCREASE FROM THE
SOUTHWEST LATER THIS MORNING WITH SCATTERED CIGS AOA 10000
FT AGL POSSIBLE AFTER MID MORNING. MID LEVEL CLOUDINESS WILL TRACK
EAST BY MONDAY EVENING WITH CLEAR SKIES EXPECTED THERE AFTER. FOR
THE KVTN TERMINAL...LOW LEVEL CLOUDINESS IS EXPECTED TO REMAIN JUST
TO THE EAST OF THE TERMINAL THIS MORNING...IMPACTING KANW AND KONL
WITH CIGS BLO 1000 FT AGL AND VSBYS DOWN TO A MILE. MID LEVEL
CLOUDINESS WILL INCREASE EARLY THIS AFTERNOON...WITH SCATTERED TO
BROKEN CIGS AON 10000 FT AGL POSSIBLE AFTER 21Z. AT BOTH
TERMINALS...SOUTHWESTERLY WINDS AROUND 10 KTS ARE EXPECTED
TODAY...WITH A SHIFT TO THE WEST AT 10 KTS TONIGHT.
CLB
PREV DISCUSSION... /ISSUED 303 AM CST MON DEC 17 2012/
DISCUSSION...SURFACE LOW PRESSURE WILL DEVELOP FROM NORTHERN WYOMING
TOWARD NORTHWEST NEBRASKA BY THIS AFTERNOON. SOUTH TO SOUTHWEST
WINDS ARE EXPECTED ACROSS THE FORECAST AREA TODAY AHEAD OF THE LOW.
850 MB TEMPERATURES WILL WARM SEVERAL DEGREES OVER THOSE OF
SUNDAY...AND EXPECTING HIGHS TO ALSO BE SEVERAL DEGREES WARMER AS
THAT WARMER AIR ALOFT MIXES TO THE SURFACE. THE ONE EXCEPTION FOR
THE WARMER HIGHS WILL BE ACROSS FAR SOUTHWEST NEBRASKA...WHERE
VISIBLE SATELLITE IMAGERY FROM LATE SUNDAY AFTERNOON STILL REVEALED
A FAIRLY DENSE SNOWPACK. AS THE AFOREMENTIONED SURFACE LOW MOVES
EAST TONIGHT AND TUESDAY...EXPECT A PACIFIC COLD FRONT TO SWEEP
SOUTHEAST ACROSS THE AREA. THIS FRONT WILL BRING A FEW DEGREES OF
COOLING FOR TUESDAY...ESPECIALLY ACROSS NORTH CENTRAL AND NORTHWEST
NEBRASKA.
ALL EYES THEN ON THE SYSTEM POISED TO AFFECT THE AREA WEDNESDAY. THE
GEM...ECMWF...AND GFS ARE ALL FAIRLY SIMILAR WITH THE TRACK OF THE
SYSTEM. THEY DEEPEN A SURFACE LOW BY MIDDAY WEDNESDAY ACROSS THE
TX/OK PANHANDLE REGION...AND THEN TRACK THE LOW EAST ALONG THE KS/OK
BORDER WEDNESDAY AFTERNOON AND NIGHT. IN THE UPPER LEVELS...A LOW
SHOULD TRACK EASTWARD ACROSS OR VERY CLOSE TO SOUTHWEST AND SOUTHERN
NEBRASKA. THE NAM AND SREF CONTINUE TO BE THE FARTHEST NORTH WITH
BOTH THE SURFACE AND UPPER LEVEL LOWS...BUT ARE TRENDING A LITTLE
SOUTH WITH EACH RUN. WILL DISCARD THE NAM/SREF SOLUTIONS AS THEY
CONTINUE TO TREND SLOWLY SOUTH...AND FOCUS MORE ON THE CONSISTENT
ECMWF AND GFS. NATIONAL GUIDANCE ALSO SHIED AWAY FROM THE NAM...AND
INCORPORATED THE LATEST GFS AND ECMWF INTO THEIR PRECIPITATION
FORECAST. THE NATIONAL FORECAST MATCHED CLOSE TO OUR LOCAL
FORECAST...AND HAS AROUND TWO INCHES OF SNOW ACCUMULATION ALONG
I-80...WITH LESS TO THE NORTH AND MORE TO THE SOUTH. NEARLY FOUR
INCHES IS POSSIBLE TOWARD THE NE/KS BORDER. THIS SNOW EVENT WILL
LARGELY BE DRIVEN BY STRONG FRONTOGENESIS...AND WILL NEED TO WATCH
FOR SIGNS OF POSSIBLE BANDING AND HIGHER SNOWFALL AMOUNTS THAN
CURRENTLY FORECASTED.
AFTER THIS EVENT...SEVERAL DAYS OF DRY AND NEAR SEASONABLE
TEMPERATURES ARE EXPECTED. MODELS BEYOND THE FORECAST PERIOD HINTING
AT A POSSIBLE STORM SYSTEM ORGANIZING ON OR AROUND CHRISTMAS. THIS
WILL BE MONITORED VERY CLOSELY THE NEXT FEW DAYS.
TAYLOR
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...COLE
AVIATION/TODAY...KECK
AREA FORECAST DISCUSSION
NWS HASTINGS NE
527 AM CST MON DEC 17 2012
.AVIATION...12Z KGRI TAF. VFR CONDITIONS EXPECTED THROUGH MUCH OF
THE TAF PERIOD...WITH LIFR CONDITIONS NOT OUT OF THE QUESTION FOR
A TIME THIS MORNING. BIGGEST CONCERN WITHIN THE NEXT SIX HOURS IS
AN AREA OF STRATUS...CURRENTLY NEAR KODX AND KBVN...MOVING
SOUTHEAST AT AROUND 20KTS. GIVEN THE CURRENT MOVEMENT OF THIS
STRATUS DECK...THE EXTREME WESTERN PERIPHERY COULD CLIP KGRI
STARTING AROUND 14Z. IF THE PATH OF THIS DECK SHIFTS SLIGHTLY TO
THE EAST...OR IF THE WESTERN EDGE OF THIS DECK ERODES
SOMEWHAT...THEN KGRI COULD ESCAPE WITH VFR CONDITIONS THROUGHOUT
THE TAF PERIOD. THERE ARE NOT HOWEVER ANY SUCH INDICATIONS OF THIS
DECK CHANGING PATH FOR ERODING AND GIVEN THIS...OPTED TO GO WITH
TEMPO LIFR CEILINGS AT KGRI 14-17Z. ASSUMING THE STRATUS CLEARS
THE AREA BY MIDDAY...MID LEVEL CLOUDS WITH CEILINGS NEAR 8000FT
AGL SHOULD BE ALL THAT IS LEFT TO CONTEND WITH THROUGH THE
REMAINDER OF THE TAF PERIOD. THE SURFACE WIND WILL VARY FROM THE
WEST/NORTHWEST TO THE SOUTHWEST THROUGH THE TAF PERIOD...AND
VISIBILITY RESTRICTIONS ARE NOT CURRENTLY EXPECTED THROUGH THE
NEXT 24 HOURS.
&&
.PREV DISCUSSION... /ISSUED 516 AM CST MON DEC 17 2012/
SHORT TERM...THROUGH WEDNESDAY NIGHT. THE PRIMARY CONCERN DURING
THE NEXT 72 HOURS CONTINUES TO BE STILL APPEARS TO BE OUR FIRST
WIDESPREAD ACCUMULATING SNOW/BLOWING SNOW EVENT OF THE SEASON WED
INTO WED NIGHT. OVERALL LITTLE HAS CHANGED IN PREVIOUS
THINKING...AS CONFIDENCE IS FAIRLY HIGH THAT HEADLINE-WORTHY
CONDITIONS FEATURING AT LEAST A FEW INCHES OF SNOW AND PLENTY OF
WIND BE REALIZED FOR MOST IF NOT ALL OF THE AREA...BUT THE DETAILS
REGARDING TOTAL ACCUMULATION POTENTIAL ARE STILL UNCERTAIN...AND
CAUTION IS ADVISED AGAINST TAKING THE CURRENT SNOWFALL FORECAST
TOO LITERALLY JUST YET AS THE SYSTEM IS STILL WELL OUT OVER THE
PACIFIC.
STARTING OFF AT 09Z THIS MORNING...THERE ARE A FEW PESKY ISSUES TO
CONSIDER WELL BEFORE THE WED STORM ARRIVES. OBJECTIVE SURFACE
ANALYSIS FEATURES A WEAKISH 1007MB LOW OVER THE FAR NORTHERN
CWA...WITH A VERY SUBTLE TROUGH AXIS TRAILING SOUTH NEAR THE
HIGHWAY 281 CORRIDOR...DOING LITTLE MORE THAN SEPARATING A LIGHT
BUT STEADY WESTERLY BREEZE IN WESTERN COUNTIES...FROM SLIGHTLY
MORE SOUTHERLY LIGHT BREEZES IN THE EAST. TEMPS EARLY THIS
MORNING HAVE TRENDED A FEW DEGREES WARMER THAN EARLIER
FORECAST...WITH LOWS LIKELY ENDING UP IN THE MID 20S MOST
AREAS...EXCEPT FOR COLDER IN THE TYPICAL DAWSON/VALLEY COUNTIES
CORRIDOR. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA
REVEAL A MODEST MID LEVEL SHORTWAVE TROUGH AXIS TRACKING DIRECTLY
OVER THE CWA AT THIS HOUR...ALTHOUGH WITH THE MAJORITY OF UPWARD
FORCING ALREADY WELL OFF TO THE EAST...SKIES HAVE LARGELY CLEARED
BEHIND THIS UPPER TROUGH AXIS...WHICH ACTUALLY BROUGHT A NARROW
LINE OF LIGHT SLEET SHOWERS TO PRIMARILY THE SOUTHWESTERN 1/4 OF
THE CWA ON SUNDAY EVENING. UNFORTUNATELY...WHAT ORIGINALLY
APPEARED TO BE A FAIRLY STRAIGHTFORWARD SKY COVER FORECAST HAS
BEEN COMPLICATED BY A FAIRLY SOLID PROTRUSION OF VERY LOW STRATUS
THAT IS CURRENTLY SINKING SOUTH ACROSS NORTH CENTRAL
NEBRASKA...AND IS POISED TO OVERTAKE AT LEAST A FEW COUNTIES IN
THE CWA NORTH OF HIGHWAY 92 OVER THE NEXT FEW HOURS. THIS LOW
CLOUD DECK IS ALSO ASSOCIATED WITH AT LEAST PATCHY FOG WITH
VISIBILITY AROUND/UNDER 1 MILE.
FORECAST WISE...THE OBVIOUS VERY SHORT TERM ISSUE TODAY IS THE
AFOREMENTIONED LOW STRATUS JUST NOW MOVING INTO OUR FAR NORTHERN
COUNTIES...AS THIS WAS NOT WELL-ANTICIPATED BY MODELS AT ALL. THE
LATEST RAP RUNS HAVE FINALLY CAUGHT ONTO IT SOMEWHAT PER THE
950-925MB RELATIVE HUMIDITY FIELDS...AND THUS THE GENERAL
EXPECTATION IS THAT THIS STRATUS AND ASSOCIATED FOG WILL IN FACT
INVADE ROUGHLY THE 5 NORTHEASTERN-MOST COUNTIES SUCH AS
NANCE/GREELEY OVER THE NEXT FEW HOURS...AND POSSIBLY HANG AROUND
WELL INTO THE DAYLIGHT HOURS BEFORE FINALLY PUSHING OUT TO THE
NORTHEAST BY EARLY-MID AFTERNOON. ALTHOUGH THIS STRATUS IS
CURRENTLY NOT EXPECTED TO SINK AS FAR SOUTHWEST AS GRAND
ISLAND/HASTINGS...THIS WILL BEAR WATCHING AS IT COULD GET SOMEWHAT
CLOSE. ALTHOUGH AM CURRENTLY NOT AWARE OF ANY DENSE FOG ASSOCIATED
WITH THIS STRATUS DECK...CURRENTLY HAVE PATCHY FOG IN THE GRIDS
THROUGH 15Z IN BOTH THE NORTHEASTERN AND FAR SOUTHERN CWA...WITH
THE LATTER ASSOCIATED WITH A COMPLETELY SEPARATE AREA OF LOW
STRATUS BARELY SKIRTING SOUTH OF THE AREA ACROSS CENTRAL KS.
MOVING ON TO OTHER ELEMENTS OF TODAY/S FORECAST...THOSE AREAS THAT
DON/T GET SOCKED IN SHOULD REALIZE QUITE A BIT OF SUNSHINE
TODAY...ALTHOUGH AT LEAST THIN MID/HIGH CLOUDS WILL BE ON THE
INCREASE FROM THE WEST THIS AFTERNOON AHEAD OF THE NEXT VERY
SUBTLE MID LEVEL WAVE. AT THE SURFACE...LOW PRESSURE DEVELOPING
ALONG AN AXIS FROM MT TO NORTHWEST NEB TODAY WILL GRADUALLY TURN
BREEZES MORE SOUTHERLY...WITH SUSTAINED SPEEDS AT LEAST 10-15 MPH
IN MOST AREAS WITH SOME HIGHER GUSTS. RAISED HIGHS TEMPS 1-3
DEGREES FROM PREVIOUS FORECAST IN SOME AREAS...BUT OVERALL SIMILAR
TO PREVIOUS WITH MOST NEB ZONES MID-UPPER 40S AND KS ZONES MAINLY
LOW-MID 50S.
TONIGHT...THE NEXT MID LEVEL SHORTWAVE TROUGH WILL TRACK PRIMARILY
ACROSS THE NORTHERN 1/2 OF NEB...WITH ISENTROPIC LIFT AHEAD OF
THIS WAVE POSSIBLY SPARKING SOME FLURRIES OR LIGHT ACCUMULATING
SNOW WITHIN 100 MILES OR SO NORTH/NORTHEAST OF THE CWA...BUT AM
NOT FORECASTING ANY SNOW TO AFFECT OUR LOCAL AREA AT THIS TIME. A
SURFACE LOW ASSOCIATED WITH THIS WAVE WILL TRACK ACROSS NORTHERN
NEB THROUGH THE NIGHT...SIMILAR TO THE ONE THIS MORNING EXCEPT
STRONGER. THIS WILL INDUCE A NOTICEABLY WESTERLY BREEZE
OVERNIGHT...WITH SUSTAINED SPEEDS LIKELY NEAR OR EXCEEDING 15 MPH
FOR AT LEAST A FEW HOURS. DESPITE MOSTLY CLEAR SKIES...THESE WEST
WINDS SHOULD HELP HOLD TEMPS UP FAIRLY EFFICIENTLY. MADE LITTLE
CHANGE TO LOW TEMPS...KEEPING THEM PRIMARILY MID 20S...BUT WOULD
NOT BE SURPRISED TO SEE SOME AREAS HOLD UP CLOSER TO 30.
TUESDAY LOOKS TO BE A FAIRLY TRANQUIL/MILD DAY AHEAD OF THE
APPROACHING PRIMARY STORM SYSTEM...WHICH WILL FINALLY BE COMING
ONSHORE IN SOUTHERN CAL. MEANWHILE...SUBTLE SHORTWAVE RIDING WILL
DOMINATE THE CENTRAL PLAINS ALOFT...WHILE AT THE
SURFACE...FAIRLY LIGHT BUT STEADY WESTERLY BREEZES WILL PREVAIL IN
THE WAKE OF THE LOW DEPARTING EAST TOWARD THE LOWER GREAT LAKES.
MADE VERY LITTLE CHANGE TO HIGHS...AS THIS SHOULD BE THE MILDEST
DAY OF THE WEEK IN MOST AREAS AND AM AIMING FOR UPPER 40S
NORTH/NEAR 50 TRI-CITIES AND MID-UPPER 50S KS ZONES.
TUES NIGHT...IT REMAIN PRECIP FREE ACROSS THE CWA...ALTHOUGH
CHANGES WILL GET UNDERWAY AS EAST-NORTHEAST SURFACE WINDS RAMP UP
TO 15+ MPH AS THE NIGHT GOES ON...IN RESPONSE TO CYCLOGENESIS
TAKING PLACE IN THE SOUTHEAST CO/OK PANHANDLE AREA. ALOFT...THERE
IS GOOD MODEL CONSENSUS AMONGST THE NAM/GFS/ECMWF THAT THE
POWERFUL SHORTWAVE AXIS WILL BE NEAR THE 4-CORNERS AT 12Z WED
MORNING. FOR LOW TEMPS...ALMOST NO CHANGE WITH UPPER 20S/LOW 30S.
LAST BUT CERTAINLY NOT LEAST...THE WEDNESDAY INTO WED NIGHT
PERIODS PROMISE TO BE QUITE ACTIVE...BUT AS STATED AT THE
TOP...THE DETAILS REGARDING SNOW ACCUMULATIONS ARE STILL A BIT
SKETCHY. IN SHORT...MODEL CONSENSUS ON THE TRACK OF THE UPPER WAVE
IS PRETTY DECENT...AS IT MIGRATES FROM THE 4-CORNERS REGION AT
SUNRISE WEDNESDAY...TO OVER THE HEART OF NEB/KS EARLY WED
EVENING...TO SOMEWHERE OVER IA/MO BY SUNRISE THURS MORNING. THE
NAM HAS BEEN A BIT OF AN OUTLIER VERSUS OTHER MODELS IN
INTENSIFYING/CLOSING OFF THE 500MB CIRCULATION DIRECTLY OVER THE
CWA AS THE WAVE PASSES...WHICH IN TURN RESULTS IN SOME FAIRLY
CONCERNING MODEL-GENERATED SNOW AMOUNTS IN EXCESS OF 6 INCHES
MAINLY NORTH OF I-80. HOWEVER...BOTH THE GFS/ECMWF MAINTAIN A BIT
MORE SOUTHERN TRACK OF THE SYSTEM...TAKING THE PRIMARY SURFACE LOW
GENERALLY ACROSS THE OK/KS BORDER INTO CENTRAL MO...VERSUS THE NAM
WHICH TAKES THE SURFACE LOW MORE OVER THE KC METRO AREA. THIS
TRACK WILL OBVIOUSLY PROVE CRITICAL AS TO WHETHER THE NORTHERN 1/2
OR SOUTHERN 1/2 OF THE CWA WILL REALIZE THE MOST SNOW...AND FOR
NOW HAVE GENERALLY USED A BLEND OF MODEL SOLUTIONS FOR THIS
MORNING/S FORECAST...WHICH RESULTS IN A VERY ROUGH STORM TOTAL
SNOW FORECAST OF 2-4 INCHES CWA-WIDE. CERTAINLY IT IS POSSIBLE
THAT SOME AREAS COULD SEE MORE THAN THIS...BUT UNTIL THE TRACK
BECOMES A BIT CLEARER IT WOULD NOT BE WISE TO TRY PINPOINTING
HIGHER THAN THIS. ALTHOUGH THIS IS A FAIRLY PROGRESSIVE
SYSTEM...IT WILL HAVE QUITE A BIT GOING FOR IT IN TERMS OF STRONG
UPPER JET DIVERGENCE AND ASSOCIATED MID LEVEL
FRONTOGENESIS/DEFORMATION. TIMING-WISE...THE GENERAL EXPECTATION
IS THAT SNOW WILL FIRST BREAK OUT MAINLY ACROSS THE NORTHWEST 1/3
OF THE CWA/NORTHWEST OF THE TRI-CITIES/DURING THE MORNING
HOURS...AND THEN RAPIDLY EXPAND ACROSS THE REMAINDER OF THE AREA
WED AFTERNOON INTO WED EVENING...WHILE AT THE SAME TIME SUSTAINED
SPEEDS WILL RAMP UP INTO THE 20-30 MPH RANGE WITH GUSTS TO AROUND
40 MPH...FIRST FROM THE NORTHEAST AND THEN SWINGING AROUND TO THE
NORTHWEST BY EVENING. VISIBILITY RESTRICTIONS WILL BE AN ISSUE FOR
SURE...BUT NOT THINKING BLIZZARD CRITERIA OF WIDESPREAD 1/4 MILE
OR LESS AT THIS POINT. LIKELY 60-70 POPS ARE IN PLACE FOR MUCH OF
THE CWA DURING THE AFTERNOON/EVENING HOURS...AND THESE WILL LIKELY
BE RAISED FURTHER OVER THE NEXT FEW DAYS. AFTER
MIDNIGHT...LINGERED SOME 20-30 POPS WITHIN THE EASTERN 1/2 OF THE
CWA...BUT THE VAST MAJORITY OF ACCUMULATIONS SHOULD BE DONE BY
THEN...AND CERTAINLY SHOULD BE OVER WITH WELL BEFORE SUNRISE.
WINDS SHOULD ALSO DIMINISH SOMEWHAT PRIOR TO SUNRISE...RESULTING
IN IMPROVING VISIBILITIES IN ANY BLOWING SNOW. TEMPS ON WED WILL
ESSENTIALLY RISE VERY LITTLE IF ANY FROM OVERNIGHT LOWS...AND KEPT
HIGHS IN THE LOW 30S EXCEPT IN THE FAR SOUTHEAST...WHERE UPPER 30S
COULD BE ATTAINABLE. ALTHOUGH NOT EXPECTING MUCH OF AN ISSUE WITH
SLEET/FREEZING RAIN WITH THIS SYSTEM...WILL HAVE TO WATCH FAR
SOUTHEAST AREAS AROUND BELOIT KS AS THINGS FIRST GET UNDERWAY...AS
TEMPS ALOFT COULD BE JUST WARM ENOUGH FOR A BRIEF WINTRY MIX
BEFORE AN OUTRIGHT CHANGEOVER TO SNOW. FOR NOW THOUGH...HAVE KEPT
ALL MENTION OF MIXED-PHASE OUT OF THE GRIDS.
LONG TERM...STARTING 12Z THURSDAY. GUIDANCE FROM THE
EC...OPERATIONAL GFS AND GEFS-MEAN ALL SUGGEST MID AND UPPER LEVEL
RIDGING WILL PERSIST OVER THE CENTRAL CONUS THROUGHOUT THE LONG
TERM FORECAST PERIOD. THE OVERALL LACK IN KINEMATIC FORCING SHOULD
PRESENT DRY CONDITIONS AS A RESULT. GUIDANCE FROM THE EC AND
OPERATIONAL GFS SUGGEST THE DEPARTING STORM SYSTEM TO OUR EAST
WILL PROVIDE A STIFF NORTHWEST WIND TO OUR AREA THROUGH MUCH OF
THURSDAY. THE INCREASING POTENTIAL FOR FRESH SNOW PACK ACROSS THE
AREA...WORKING IN CONCERT WITH LOW LEVEL COLD AIR
ADVECTION...MEANS TEMPERATURES WILL PROBABLY HAVE DIFFICULTY
CLIMBING ALL THAT FAR ON THURSDAY. GIVEN THIS...WENT AHEAD AND
UNDERCUT ALLBLEND BY 2-3 DEGREES FOR MANY LOCATIONS ACROSS THE CWA
WHICH PRESENTS HIGHS IN THE LOW 30S FOR THE MOST PART. THERE IS A
CHANCE THURSDAY HIGH TEMPERATURES WILL NEED TO BE DECREASED MORE
IN THE COMING DAYS SHOULD THE ANTICIPATED SNOWFALL MATERIALIZE ON
WEDNESDAY. CLEAR SKIES AND A DECREASING LOW LEVEL WIND
FIELD...ALONG WITH A FEW INCHES OF SNOW ON THE GROUND...WILL
LIKELY PRESENT A COLD NIGHT THURSDAY NIGHT. ~30 DEGREE TEMPERATURE
DROP-OFFS DO NOT SEEM UNREASONABLE GIVEN THE EXPECTED SYNOPTIC
SETUP...WHICH WOULD PROVIDE OVERNIGHT LOWS GENERALLY IN THE LOW
TEENS. ALLBLEND ONLY PROVIDE LOWS IN THE MID TO UPPER TEENS AND AS
A RESULT...WENT AHEAD AND UNDERCUT ALLBLEND BY A COUPLE DEGREES
BUT MUCH LIKE THE HIGHS ON THURSDAY...THERE IS A POSSIBILITY THAT
THURSDAY NIGHT LOWS WILL NEED TO BE DECREASED A BIT MORE IN THE
COMING DAYS. A PERSISTENT WESTERLY COMPONENT TO THE LOW LEVEL WIND
FIELD...ALONG WITH MODEST LOW LEVEL WARM AIR ADVECTION...SHOULD
HELP THE SNOW PACK ERODE QUITE A BIT HEADING INTO FRIDAY...WITH A
RESULTANT WARMING TREND EXPECTED. NO REAL REASON TO DISAGREE WITH
ALLBLEND WHICH PRESENTED AFTERNOON HIGHS IN THE 30S AND 40S AND
FRIDAY NIGHT LOWS IN THE MID TO UPPER TEENS. THERE ARE INDICATIONS
FROM THE EC AND OPERATIONAL GFS OF A BACKDOOR COLD FRONT PUSHING
ACROSS THE AREA HEADING INTO THE DAY SATURDAY...WITH ALLBLEND
PRESENTING A SUBTLE COOLING TREND TO FINISH THE LONG TERM FORECAST
PERIOD. NO REASON TO DISAGREE WITH ALLBLEND SO LEFT SUNDAY HIGH
TEMPERATURE IN THE 30S FOR MOST LOCATIONS ACROSS THE CWA.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
AVIATION/LONG TERM...BRYANT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
516 AM CST MON DEC 17 2012
.SHORT TERM...THROUGH WEDNESDAY NIGHT. THE PRIMARY CONCERN DURING
THE NEXT 72 HOURS CONTINUES TO BE STILL APPEARS TO BE OUR FIRST
WIDESPREAD ACCUMULATING SNOW/BLOWING SNOW EVENT OF THE SEASON WED
INTO WED NIGHT. OVERALL LITTLE HAS CHANGED IN PREVIOUS
THINKING...AS CONFIDENCE IS FAIRLY HIGH THAT HEADLINE-WORTHY
CONDITIONS FEATURING AT LEAST A FEW INCHES OF SNOW AND PLENTY OF
WIND BE REALIZED FOR MOST IF NOT ALL OF THE AREA...BUT THE DETAILS
REGARDING TOTAL ACCUMULATION POTENTIAL ARE STILL UNCERTAIN...AND
CAUTION IS ADVISED AGAINST TAKING THE CURRENT SNOWFALL FORECAST
TOO LITERALLY JUST YET AS THE SYSTEM IS STILL WELL OUT OVER THE
PACIFIC.
STARTING OFF AT 09Z THIS MORNING...THERE ARE A FEW PESKY ISSUES TO
CONSIDER WELL BEFORE THE WED STORM ARRIVES. OBJECTIVE SURFACE
ANALYSIS FEATURES A WEAKISH 1007MB LOW OVER THE FAR NORTHERN
CWA...WITH A VERY SUBTLE TROUGH AXIS TRAILING SOUTH NEAR THE
HIGHWAY 281 CORRIDOR...DOING LITTLE MORE THAN SEPARATING A LIGHT
BUT STEADY WESTERLY BREEZE IN WESTERN COUNTIES...FROM SLIGHTLY
MORE SOUTHERLY LIGHT BREEZES IN THE EAST. TEMPS EARLY THIS
MORNING HAVE TRENDED A FEW DEGREES WARMER THAN EARLIER
FORECAST...WITH LOWS LIKELY ENDING UP IN THE MID 20S MOST
AREAS...EXCEPT FOR COLDER IN THE TYPICAL DAWSON/VALLEY COUNTIES
CORRIDOR. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA
REVEAL A MODEST MID LEVEL SHORTWAVE TROUGH AXIS TRACKING DIRECTLY
OVER THE CWA AT THIS HOUR...ALTHOUGH WITH THE MAJORITY OF UPWARD
FORCING ALREADY WELL OFF TO THE EAST...SKIES HAVE LARGELY CLEARED
BEHIND THIS UPPER TROUGH AXIS...WHICH ACTUALLY BROUGHT A NARROW
LINE OF LIGHT SLEET SHOWERS TO PRIMARILY THE SOUTHWESTERN 1/4 OF
THE CWA ON SUNDAY EVENING. UNFORTUNATELY...WHAT ORIGINALLY
APPEARED TO BE A FAIRLY STRAIGHTFORWARD SKY COVER FORECAST HAS
BEEN COMPLICATED BY A FAIRLY SOLID PROTRUSION OF VERY LOW STRATUS
THAT IS CURRENTLY SINKING SOUTH ACROSS NORTH CENTRAL
NEBRASKA...AND IS POISED TO OVERTAKE AT LEAST A FEW COUNTIES IN
THE CWA NORTH OF HIGHWAY 92 OVER THE NEXT FEW HOURS. THIS LOW
CLOUD DECK IS ALSO ASSOCIATED WITH AT LEAST PATCHY FOG WITH
VISIBILITY AROUND/UNDER 1 MILE.
FORECAST WISE...THE OBVIOUS VERY SHORT TERM ISSUE TODAY IS THE
AFOREMENTIONED LOW STRATUS JUST NOW MOVING INTO OUR FAR NORTHERN
COUNTIES...AS THIS WAS NOT WELL-ANTICIPATED BY MODELS AT ALL. THE
LATEST RAP RUNS HAVE FINALLY CAUGHT ONTO IT SOMEWHAT PER THE
950-925MB RELATIVE HUMIDITY FIELDS...AND THUS THE GENERAL
EXPECTATION IS THAT THIS STRATUS AND ASSOCIATED FOG WILL IN FACT
INVADE ROUGHLY THE 5 NORTHEASTERN-MOST COUNTIES SUCH AS
NANCE/GREELEY OVER THE NEXT FEW HOURS...AND POSSIBLY HANG AROUND
WELL INTO THE DAYLIGHT HOURS BEFORE FINALLY PUSHING OUT TO THE
NORTHEAST BY EARLY-MID AFTERNOON. ALTHOUGH THIS STRATUS IS
CURRENTLY NOT EXPECTED TO SINK AS FAR SOUTHWEST AS GRAND
ISLAND/HASTINGS...THIS WILL BEAR WATCHING AS IT COULD GET SOMEWHAT
CLOSE. ALTHOUGH AM CURRENTLY NOT AWARE OF ANY DENSE FOG ASSOCIATED
WITH THIS STRATUS DECK...CURRENTLY HAVE PATCHY FOG IN THE GRIDS
THROUGH 15Z IN BOTH THE NORTHEASTERN AND FAR SOUTHERN CWA...WITH
THE LATTER ASSOCIATED WITH A COMPLETELY SEPARATE AREA OF LOW
STRATUS BARELY SKIRTING SOUTH OF THE AREA ACROSS CENTRAL KS.
MOVING ON TO OTHER ELEMENTS OF TODAY/S FORECAST...THOSE AREAS THAT
DON/T GET SOCKED IN SHOULD REALIZE QUITE A BIT OF SUNSHINE
TODAY...ALTHOUGH AT LEAST THIN MID/HIGH CLOUDS WILL BE ON THE
INCREASE FROM THE WEST THIS AFTERNOON AHEAD OF THE NEXT VERY
SUBTLE MID LEVEL WAVE. AT THE SURFACE...LOW PRESSURE DEVELOPING
ALONG AN AXIS FROM MT TO NORTHWEST NEB TODAY WILL GRADUALLY TURN
BREEZES MORE SOUTHERLY...WITH SUSTAINED SPEEDS AT LEAST 10-15 MPH
IN MOST AREAS WITH SOME HIGHER GUSTS. RAISED HIGHS TEMPS 1-3
DEGREES FROM PREVIOUS FORECAST IN SOME AREAS...BUT OVERALL SIMILAR
TO PREVIOUS WITH MOST NEB ZONES MID-UPPER 40S AND KS ZONES MAINLY
LOW-MID 50S.
TONIGHT...THE NEXT MID LEVEL SHORTWAVE TROUGH WILL TRACK PRIMARILY
ACROSS THE NORTHERN 1/2 OF NEB...WITH ISENTROPIC LIFT AHEAD OF
THIS WAVE POSSIBLY SPARKING SOME FLURRIES OR LIGHT ACCUMULATING
SNOW WITHIN 100 MILES OR SO NORTH/NORTHEAST OF THE CWA...BUT AM
NOT FORECASTING ANY SNOW TO AFFECT OUR LOCAL AREA AT THIS TIME. A
SURFACE LOW ASSOCIATED WITH THIS WAVE WILL TRACK ACROSS NORTHERN
NEB THROUGH THE NIGHT...SIMILAR TO THE ONE THIS MORNING EXCEPT
STRONGER. THIS WILL INDUCE A NOTICEABLY WESTERLY BREEZE
OVERNIGHT...WITH SUSTAINED SPEEDS LIKELY NEAR OR EXCEEDING 15 MPH
FOR AT LEAST A FEW HOURS. DESPITE MOSTLY CLEAR SKIES...THESE WEST
WINDS SHOULD HELP HOLD TEMPS UP FAIRLY EFFICIENTLY. MADE LITTLE
CHANGE TO LOW TEMPS...KEEPING THEM PRIMARILY MID 20S...BUT WOULD
NOT BE SURPRISED TO SEE SOME AREAS HOLD UP CLOSER TO 30.
TUESDAY LOOKS TO BE A FAIRLY TRANQUIL/MILD DAY AHEAD OF THE
APPROACHING PRIMARY STORM SYSTEM...WHICH WILL FINALLY BE COMING
ONSHORE IN SOUTHERN CAL. MEANWHILE...SUBTLE SHORTWAVE RIDING WILL
DOMINATE THE CENTRAL PLAINS ALOFT...WHILE AT THE
SURFACE...FAIRLY LIGHT BUT STEADY WESTERLY BREEZES WILL PREVAIL IN
THE WAKE OF THE LOW DEPARTING EAST TOWARD THE LOWER GREAT LAKES.
MADE VERY LITTLE CHANGE TO HIGHS...AS THIS SHOULD BE THE MILDEST
DAY OF THE WEEK IN MOST AREAS AND AM AIMING FOR UPPER 40S
NORTH/NEAR 50 TRI-CITIES AND MID-UPPER 50S KS ZONES.
TUES NIGHT...IT REMAIN PRECIP FREE ACROSS THE CWA...ALTHOUGH
CHANGES WILL GET UNDERWAY AS EAST-NORTHEAST SURFACE WINDS RAMP UP
TO 15+ MPH AS THE NIGHT GOES ON...IN RESPONSE TO CYCLOGENESIS
TAKING PLACE IN THE SOUTHEAST CO/OK PANHANDLE AREA. ALOFT...THERE
IS GOOD MODEL CONSENSUS AMONGST THE NAM/GFS/ECMWF THAT THE
POWERFUL SHORTWAVE AXIS WILL BE NEAR THE 4-CORNERS AT 12Z WED
MORNING. FOR LOW TEMPS...ALMOST NO CHANGE WITH UPPER 20S/LOW 30S.
LAST BUT CERTAINLY NOT LEAST...THE WEDNESDAY INTO WED NIGHT
PERIODS PROMISE TO BE QUITE ACTIVE...BUT AS STATED AT THE
TOP...THE DETAILS REGARDING SNOW ACCUMULATIONS ARE STILL A BIT
SKETCHY. IN SHORT...MODEL CONSENSUS ON THE TRACK OF THE UPPER WAVE
IS PRETTY DECENT...AS IT MIGRATES FROM THE 4-CORNERS REGION AT
SUNRISE WEDNESDAY...TO OVER THE HEART OF NEB/KS EARLY WED
EVENING...TO SOMEWHERE OVER IA/MO BY SUNRISE THURS MORNING. THE
NAM HAS BEEN A BIT OF AN OUTLIER VERSUS OTHER MODELS IN
INTENSIFYING/CLOSING OFF THE 500MB CIRCULATION DIRECTLY OVER THE
CWA AS THE WAVE PASSES...WHICH IN TURN RESULTS IN SOME FAIRLY
CONCERNING MODEL-GENERATED SNOW AMOUNTS IN EXCESS OF 6 INCHES
MAINLY NORTH OF I-80. HOWEVER...BOTH THE GFS/ECMWF MAINTAIN A BIT
MORE SOUTHERN TRACK OF THE SYSTEM...TAKING THE PRIMARY SURFACE LOW
GENERALLY ACROSS THE OK/KS BORDER INTO CENTRAL MO...VERSUS THE NAM
WHICH TAKES THE SURFACE LOW MORE OVER THE KC METRO AREA. THIS
TRACK WILL OBVIOUSLY PROVE CRITICAL AS TO WHETHER THE NORTHERN 1/2
OR SOUTHERN 1/2 OF THE CWA WILL REALIZE THE MOST SNOW...AND FOR
NOW HAVE GENERALLY USED A BLEND OF MODEL SOLUTIONS FOR THIS
MORNING/S FORECAST...WHICH RESULTS IN A VERY ROUGH STORM TOTAL
SNOW FORECAST OF 2-4 INCHES CWA-WIDE. CERTAINLY IT IS POSSIBLE
THAT SOME AREAS COULD SEE MORE THAN THIS...BUT UNTIL THE TRACK
BECOMES A BIT CLEARER IT WOULD NOT BE WISE TO TRY PINPOINTING
HIGHER THAN THIS. ALTHOUGH THIS IS A FAIRLY PROGRESSIVE
SYSTEM...IT WILL HAVE QUITE A BIT GOING FOR IT IN TERMS OF STRONG
UPPER JET DIVERGENCE AND ASSOCIATED MID LEVEL
FRONTOGENESIS/DEFORMATION. TIMING-WISE...THE GENERAL EXPECTATION
IS THAT SNOW WILL FIRST BREAK OUT MAINLY ACROSS THE NORTHWEST 1/3
OF THE CWA/NORTHWEST OF THE TRI-CITIES/DURING THE MORNING
HOURS...AND THEN RAPIDLY EXPAND ACROSS THE REMAINDER OF THE AREA
WED AFTERNOON INTO WED EVENING...WHILE AT THE SAME TIME SUSTAINED
SPEEDS WILL RAMP UP INTO THE 20-30 MPH RANGE WITH GUSTS TO AROUND
40 MPH...FIRST FROM THE NORTHEAST AND THEN SWINGING AROUND TO THE
NORTHWEST BY EVENING. VISIBILITY RESTRICTIONS WILL BE AN ISSUE FOR
SURE...BUT NOT THINKING BLIZZARD CRITERIA OF WIDESPREAD 1/4 MILE
OR LESS AT THIS POINT. LIKELY 60-70 POPS ARE IN PLACE FOR MUCH OF
THE CWA DURING THE AFTERNOON/EVENING HOURS...AND THESE WILL LIKELY
BE RAISED FURTHER OVER THE NEXT FEW DAYS. AFTER
MIDNIGHT...LINGERED SOME 20-30 POPS WITHIN THE EASTERN 1/2 OF THE
CWA...BUT THE VAST MAJORITY OF ACCUMULATIONS SHOULD BE DONE BY
THEN...AND CERTAINLY SHOULD BE OVER WITH WELL BEFORE SUNRISE.
WINDS SHOULD ALSO DIMINISH SOMEWHAT PRIOR TO SUNRISE...RESULTING
IN IMPROVING VISIBILITIES IN ANY BLOWING SNOW. TEMPS ON WED WILL
ESSENTIALLY RISE VERY LITTLE IF ANY FROM OVERNIGHT LOWS...AND KEPT
HIGHS IN THE LOW 30S EXCEPT IN THE FAR SOUTHEAST...WHERE UPPER 30S
COULD BE ATTAINABLE. ALTHOUGH NOT EXPECTING MUCH OF AN ISSUE WITH
SLEET/FREEZING RAIN WITH THIS SYSTEM...WILL HAVE TO WATCH FAR
SOUTHEAST AREAS AROUND BELOIT KS AS THINGS FIRST GET UNDERWAY...AS
TEMPS ALOFT COULD BE JUST WARM ENOUGH FOR A BRIEF WINTRY MIX
BEFORE AN OUTRIGHT CHANGEOVER TO SNOW. FOR NOW THOUGH...HAVE KEPT
ALL MENTION OF MIXED-PHASE OUT OF THE GRIDS.
.LONG TERM...STARTING 12Z THURSDAY. GUIDANCE FROM THE
EC...OPERATIONAL GFS AND GEFS-MEAN ALL SUGGEST MID AND UPPER
LEVEL RIDGING WILL PERSIST OVER THE CENTRAL CONUS THROUGHOUT THE
LONG TERM FORECAST PERIOD. THE OVERALL LACK IN KINEMATIC FORCING
SHOULD PRESENT DRY CONDITIONS AS A RESULT. GUIDANCE FROM THE EC
AND OPERATIONAL GFS SUGGEST THE DEPARTING STORM SYSTEM TO OUR EAST
WILL PROVIDE A STIFF NORTHWEST WIND TO OUR AREA THROUGH MUCH OF
THURSDAY. THE INCREASING POTENTIAL FOR FRESH SNOWPACK ACROSS THE
AREA...WORKING IN CONCERT WITH LOW LEVEL COLD AIR
ADVECTION...MEANS TEMPERATURES WILL PROBABLY HAVE DIFFICULTY
CLIMBING ALL THAT FAR ON THURSDAY. GIVEN THIS...WENT AHEAD AND
UNDERCUT ALLBLEND BY 2-3 DEGREES FOR MANY LOCATIONS ACROSS THE CWA
WHICH PRESENTS HIGHS IN THE LOW 30S FOR THE MOST PART. THERE IS A
CHANCE THURSDAY HIGH TEMPERATURES WILL NEED TO BE DECREASED MORE
IN THE COMING DAYS SHOULD THE ANTICIPATED SNOWFALL MATERIALIZE ON
WEDNESDAY. CLEAR SKIES AND A DECREASING LOW LEVEL WIND
FIELD...ALONG WITH A FEW INCHES OF SNOW ON THE GROUND...WILL
LIKELY PRESENT A COLD NIGHT THURSDAY NIGHT. ~30 DEGREE TEMPERATURE
DROP-OFFS DO NOT SEEM UNREASONABLE GIVEN THE EXPECTED SYNOPTIC
SETUP...WHICH WOULD PROVIDE OVERNIGHT LOWS GENERALLY IN THE LOW
TEENS. ALLBLEND ONLY PROVIDE LOWS IN THE MID TO UPPER TEENS AND AS
A RESULT...WENT AHEAD AND UNDERCUT ALLBLEND BY A COUPLE DEGREES
BUT MUCH LIKE THE HIGHS ON THURSDAY...THERE IS A POSSIBILITY THAT
THURSDAY NIGHT LOWS WILL NEED TO BE DECREASED A BIT MORE IN THE
COMING DAYS. A PERSISTENT WESTERLY COMPONENT TO THE LOW LEVEL WIND
FIELD...ALONG WITH MODEST LOW LEVEL WARM AIR ADVECTION...SHOULD
HELP THE SNOWPACK ERODE QUITE A BIT HEADING INTO FRIDAY...WITH A
RESULTANT WARMING TREND EXPECTED. NO REAL REASON TO DISAGREE WITH
ALLBLEND WHICH PRESENTED AFTERNOON HIGHS IN THE 30S AND 40S AND
FRIDAY NIGHT LOWS IN THE MID TO UPPER TEENS. THERE ARE INDICATIONS
FROM THE EC AND OPERATIONAL GFS OF A BACKDOOR COLD FRONT PUSHING
ACROSS THE AREA HEADING INTO THE DAY SATURDAY...WITH ALLBLEND
PRESENTING A SUBTLE COOLING TREND TO FINISH THE LONG TERM FORECAST
PERIOD. NO REASON TO DISAGREE WITH ALLBLEND SO LEFT SUNDAY HIGH
TEMPERATURE IN THE 30S FOR MOST LOCATIONS ACROSS THE CWA.
&&
.PREV DISCUSSION... /ISSUED 1015 PM CST SUN DEC 16 2012/
AVIATION...06Z KGRI TAF. LOW CLOUDS HAVE MOVED FURTHER EAST AND
MID CLOUDS HAVE MOVED IN FROM THE WEST. EXPECT IT WILL BE MORE
DIFFICULT NOW FOR THE LOW CLOUDS TO SPREAD BACK INTO KGRI GIVEN
RECENT MODEL RUNS THAT PUSH A SFC TROUGH THROUGH PRIOR TO DAWN
AND TURN THE SFC WINDS TO WESTERLY. THEREFORE...HAVE REMOVED TEMPO
GROUP THAT HAD INDICATED IFR CONDITIONS FOR THE HOURS AROUND DAWN.
BELIEVE THAT VFR CONDITIONS WILL PERSIST THROUGH THE TAF VALID
PERIOD.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...BRYANT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1015 PM CST SUN DEC 16 2012
.AVIATION...06Z KGRI TAF. LOW CLOUDS HAVE MOVED FURTHER EAST AND
MID CLOUDS HAVE MOVED IN FROM THE WEST. EXPECT IT WILL BE MORE
DIFFICULT NOW FOR THE LOW CLOUDS TO SPREAD BACK INTO KGRI GIVEN
RECENT MODEL RUNS THAT PUSH A SFC TROUGH THROUGH PRIOR TO DAWN
AND TURN THE SFC WINDS TO WESTERLY. THEREFORE...HAVE REMOVED TEMPO
GROUP THAT HAD INDICATED IFR CONDITIONS FOR THE HOURS AROUND DAWN.
BELIEVE THAT VFR CONDITIONS WILL PERSIST THROUGH THE TAF VALID
PERIOD.
&&
.PREV DISCUSSION... /ISSUED 900 PM CST SUN DEC 16 2012/
UPDATE...SNOW FLURRIES HAVE BEEN REPORTED WEST OF OUR CWA AND
EXPECT THESE WILL SLIDE ACROSS OUR FORECAST AREA OVER THE NEXT FEW
HOURS. ANY SNOW FLURRIES OR BRIEF LIGHT SNOW WILL LIKELY END
BEFORE DAWN. IR SATELLITE IMAGERY INDICATES COOLING CLOUD TOPS
THIS EVENING ACROSS SOUTH CENTRAL NEBRASKA AND FORECAST MODELS
SHOW A WEAK VORT MAX PRESSING EAST ACROSS THE REGION.
CONSEQUENTLY...DESPITE THE LACK OF MODEL QPF...BELIEVE THAT FLURRIES
WILL CONTINUE TO BE POSSIBLE WITH THIS UPPER TROUGH AS IT SLIDES
EAST TONIGHT.
PREV DISCUSSION... /ISSUED 337 PM CST SUN DEC 16 2012/
SHORT TERM...TONIGHT AND TOMORROW.
UPPER LEVEL SATELLITE DATA HAS SHOW A FEW SMALL DISTURBANCES
SHIFTING ACROSS THE PLAINS TODAY...ONE OF WHICH BROUGHT SOME LIGHT
SNOW TO PORTIONS OF THE CWA THIS MORNING. TRACE AMOUNTS UP NEAR
A HALF OF AN INCH WERE REPORTED...AND BY MIDDAY PRECIPITATION
TRENDS HAD FALLEN BACK TO JUST A FEW SCATTERED FLURRIES IN
NORTHEASTERN PORTIONS OF THE CWA. CLOUD COVER HAS BEEN
ANNOYING...THE NORTHEASTERN HALF OF THE CWA HAS BEEN STUCK UNDER
STUBBORN LOW LEVEL STRATUS...VS THE WESTERN HALF WHICH HAS SEEN
PLENTY OF SUN. SURFACE ANALYSIS SHOWS A RIDGE AXIS EXTENDING
THROUGH THE CENTRAL/EASTERN PORTIONS OF THE REGION...KEEPING WINDS
GENERALLY ON THE LIGHT AND AT TIMES VARIABLE SIDE. THANKS TO THE
CLOUD COVER...EASTERN LOCATIONS HAVE HUNG AROUND THE LOW 30S THIS
AFTERNOON...OUT WEST HAS REACHED INTO THE LOWER 40S.
KEPT THE FORECAST TONIGHT DRY...THOUGH MODELS ARE SHOWING ANOTHER
WEAK DISTURBANCE SWINGING THOUGH THE REGION...POTENTIALLY BRINGING
SOME ADDITIONAL LIGHT PRECIPITATION. AT THIS POINT...SHOULD ANY
PRECIPITATION FALL...IT LOOKS TO REMAIN JUST OFF TO THE
SOUTH/SOUTHWEST OF THE CWA. AT THE SURFACE...A WEAK TROUGH AXIS
GETS PUSHED THROUGH AS THE DISTURBANCE CROSSES...EVENTUALLY
BRINGING A WESTERLY COMPONENT TO THE WINDS. AHEAD OF THAT
SWITCH...CONCERNED ABOUT THE POTENTIAL FOR SOME PATCHY FOG
DEVELOPMENT...AS THE WINDS REMAIN LIGHT/CALM WITH NOT AS MUCH IN
THE WAY OF CLOUD COVER EXPECTED. WITH THE NAM/SREF BOTH SHOWING
REDUCED VISIBILITIES AND THE RAP NOT TOO FAR OUTSIDE THE CWA
BOUNDARY...DECIDED TO INSERT A PATCHY FOG MENTION ACROSS PORTIONS
OF SC NEB.
INTO MONDAY...EXPECTING TO SEE WEAK SHORTWAVE UPPER LEVEL RIDGING
OVER THE REGION...KEEPING CONDITIONS QUIET. SHOULD SEE VARIABLE
SKY COVER THROUGH THE DAY WITH UPPER LEVEL CLOUDS STREAMING IN.
AT THE SURFACE...THE CWA IS COMING UNDER INCREASING INFLUENCE OF
LOW PRESSURE DEVELOPING OVER THE HIGH PLAINS...RESULTING IN WINDS
BECOMING MORE SOUTHERLY WITH TIME. AFTER LOW TEMPERATURES TONIGHT
EXPECTED IN THE TEENS TO LOWER 20S...HIGHS ON MONDAY LOOK TO REACH
INTO THE LOWER 40S TO NEAR 50.
LONG TERM...MONDAY NIGHT THROUGH SUNDAY.
MAIN CHALLENGE REMAINS DETERMINING CHANCES AND TIMING OF SNOW FOR
WEDNESDAY/WEDNESDAY NIGHT.
WE BEGIN THE LONG TERM FORECAST MONDAY NIGHT WITH ZONAL FLOW. THE
FLOW REMAINS QUITE PROGRESSIVE AS A SIGNIFICANT TROUGH DEVELOPS IN
THE WESTERN UNITED STATES BY TUESDAY. AS A RESPONSE TO THIS
DEEPENING TROUGH TO THE WEST...PLENTY OF WARM AIR WILL ARRIVE ON
TUESDAY AND PLACE OUR HIGH TEMPERATURES WELL ABOVE NORMAL BY ABOUT
15 DEGREES OR SO. THIS ABOVE NORMAL WEATHER WILL MOST CERTAINLY
NOT LAST AS THE TROUGH PROGRESSES QUICKLY TO THE EAST AND AN
ASSOCIATED COLD FRONT SWINGS IN FROM THE NORTHWEST VERY LATE
TUESDAY NIGHT INTO WEDNESDAY. A SHARP COOL DOWN WILL ENSUE.
THE TIMELINE FOR THIS NEXT WAVE IS TRENDING TOWARD A SOONER ARRIVAL
AND SOONER EXIT. ISENTROPIC LIFT BEGINS EARLY WEDNESDAY MORNING
BEHIND A QUICKLY MOVING COLD FRONT...WITH THIS FORCING GIVING WAY
TO MID-LEVEL FRONTOGENETIC FORCING LATER IN THE DAY.
ALSO...LARGER SCALE SYNOPTIC FORCING BECOMES STRONGER AS THE DAY
WEARS ON AND IS FORECAST TO BE RESPECTABLE FOR A SHORT
TIME...ADDING ANOTHER LAYER OF FORCING TO AID IN SNOW PRODUCTION.
THE ECMWF INDICATES THAT SYNOPTIC FORCING WILL PEAK NEAR 00Z
THURSDAY. THIS WAVE IS A QUICK HITTER...HOWEVER...WITH MOST IF NOT
ALL FORCING EAST OF THE CWA BY MIDNIGHT WEDNESDAY NIGHT...WHICH
WILL ALSO END ANY SNOW PRODUCTION. WITH THIS WAVE BEING SUCH A
QUICK HITTER...SNOW AMOUNTS ARE STILL ON TRACK FOR UP TO 4 INCHES
OR SO FOR SOMEBODY NEARBY...BUT THIS PROBABLY WOULD NOT BE A
UBIQUITOUS SNOW AMOUNT. IF THIS SYSTEM SLOWS DOWN JUST A
BIT...THIS COULD MEAN MORE SNOW WITH LARGER SNOW AMOUNTS AND
PLENTY OF WIND TO CREATE DRIFTING SNOW POTENTIAL. WIND ALOFT FOR
WEDNESDAY AFTERNOON AND EVENING IS QUITE STRONG AND BLOWING SNOW
WILL BE A POTENTIAL ISSUE. THERE IS ALSO SOME DISCREPANCY AMONG
MODELS WHERE THE TRACK OF THE 700 MB CLOSED LOW WILL BE AS THE NAM
DRAGS THIS LOW ACROSS THE CENTRAL CWA...WHILE THE ECMWF TAKES THE
700 MB LOW ACROSS CENTRAL KANSAS. THE GFS DOES NOT CLOSE THE LOW
OFF...BUT DOES FAVOR A SOLUTION CLOSER TO THE ECMWF. NO QUESTION
ABOUT PRECIPITATION TYPE SO FAR...AS SOUNDINGS INDICATE ALL SNOW
WITH THIS EVENT. WE TEND TO FAVOR A MORE SOUTHERN TRACK WITH THESE
PACIFIC SYSTEMS. ALSO WEDNESDAY MAY BE A TRICKY DAY FOR HOURLY
TEMPERATURES DEPENDING ON THE TIMING OF THE COLD FRONT. WE COULD
REACH HIGHS MORE TOWARD LATE MORNING RATHER THEN IN THE AFTERNOON.
ANYWAY...TEMPERATURES WILL PROBABLY GO ALMOST NOWHERE FROM THE
LOWS ON TUESDAY NIGHT. I CONTINUED TO GO COLDER THAN ALLBLEND FOR
TEMPERATURES FOR WEDNESDAY NIGHT AND BEYOND CONSIDERING POTENTIAL
SNOW COVER.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BUFFALO NY
110 PM EST MON DEC 17 2012
.SYNOPSIS...
CLOUDY SKIES WILL PREVAIL ACROSS THE REGION TODAY WITH RAIN
RETURNING LATE THIS AFTERNOON TO SOUTHWESTERN NEW YORK STATE. A LOW
WILL TRACK ACROSS PENNSYLVANIA AND INTO SOUTHERN NEW ENGLAND WHICH
WILL BRING A STEADY RAIN INTO THE REMAINDER OF THE REGION THIS
EVENING WITH RAIN LINGERING INTO TUESDAY. WARM TEMPERATURES WILL
CONTINUE THROUGH MUCH OF THE WEEK BEFORE A TURN TOWARDS COLDER AND
MORE WINTRY WEATHER BY FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS THIS EARLY AFTERNOON SHOW THE CWA DRY...THOUGH WE
WILL LOOK SOUTHWARD FOR OUR NEXT BATCH OF RAIN. EXPECT THE RAIN
ACROSS THAT IS ACROSS SOUTHERN OHIO AND NORTHERN WV AROUND NOONTIME
TO REACH THE SOUTHERN TIER LATE THIS AFTERNOON. OTHERWISE CLOUDY
SKIES AND MILD THIS AFTERNOON.
EXPECT ABOVE NORMAL TEMPERATURES FOR MOST LOCATIONS...WITH HIGHS NEAR
OR ABOVE 50 ACROSS THE WESTERN TWO THIRDS OF THE CWA. A DEVELOPING
SOUTHWESTERLY FLOW MAY KEEP BUFFALO FROM RISING MUCH ABOVE 50...BUT
DOWNSLOPING WILL CONTINUE IN THE GENESEE VALLEY AND FINGER LAKES
REGIONS...WHERE TEMPERATURES SHOULD REACH THE LOWER TO MID 50S.
AN UPPER LEVEL TROF AND ASSOCIATED SURFACE LOW WILL TRACK FROM THE
OHIO VALLEY AND INTO THE REGION TONIGHT. NAM BUFKIT INDICATES LIFT
WELL ALOFT ASSOCIATED WITH THE UPPER TROF...AS WELL AS WARM AIR
ADVECTION IN THE MID-LEVELS. GFS/RGEM/NAM AND SREF ENSEMBLES ARE IN
EXCELLENT AGREEMENT IN TERMS OF QPF...AND GIVEN THE LARGE-SCALE
NATURE OF THE PRECIPITATION HAVE A HIGH CONFIDENCE IN MEASURABLE
PRECIPITATION TONIGHT. NOTED THE 09Z HRRR AND THE 06Z RUN OF THE
NAM ARE A BIT SLOWER THAN PREVIOUS GUIDANCE...SO TRY TO BLEND THIS
SLOWER TIMING WITH FASTER MODELS SUCH AS THE GFS. USING THIS
APPROACH...EXPECT RAIN WILL SPREAD FROM SOUTH TO NORTH THIS
EVENING...LIKELY ENTERING WESTERN PORTIONS OF THE SOUTHERN TIER
AROUND OR JUST AFTER.
THIS SHOULD BE A FAIRLY SOAKING RAINFALL...BRINGING AN AVERAGE OF A
HALF INCH OF RAIN TO THE REGION TONIGHT. LOCALLY HIGHER AMOUNTS TO
AN INCH ARE POSSIBLE...WITH THE BEST CHANCE OF THIS IN LOCATIONS
EAST OF ROCHESTER. FORTUNATELY...WARMER AIR SHOULD BE IN PLACE BY
TONIGHT...WITH ALL PRECIPITATION LIKELY FALLING AS RAIN. EXPECT
FOG WILL DEVELOP IN SOME AREAS TONIGHT
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
WIDESPREAD STEADY RAIN WILL BE ACROSS THE AREA TUESDAY MORNING IN
AREA OF STRONG ISENTROPIC ASCENT AHEAD OF THE APPROACHING SURFACE
LOW. LATEST MODELS CONTINUING TO SUGGEST THAT THE LOW WILL REFORM
ALONG THE SOUTHERN NEW ENGLAND COAST DURING THE DAY TUESDAY AND MOVE
UP THE NEW ENGLAND COAST. AS THIS HAPPENS...COLDER AIR WILL BE DRAWN
INTO THE STATE TUESDAY AFTERNOON AND TUESDAY NIGHT. THIS SHOULD
RESULT IN A GRADUAL TRANSITION TO SOME SCATTERED LAKE/OROGRAPHICALLY
ENHANCED RAIN/SNOW SHOWERS WITH ALL SNOW BECOMING LIKELY OVER THE
HIGHER TERRAIN. ANY SNOW ACCUMULATIONS SHOULD BE LIMITED TO LESS
THAN 2 INCHES AND LIKELY CONFINED TO THE HIGHER TERRAIN TUESDAY
NIGHT.
BUILDING HEIGHTS EXPECTED ON WEDNESDAY IN RESPONSE TO STRONG
SHORTWAVE MOVING ACROSS THE FOUR CORNERS REGION. WEAK SURFACE RIDGE
BUILDING ACROSS THE REGION SHOULD BRING MAINLY QUIET WEATHER
WEDNESDAY AND WEDNESDAY NIGHT...ALTHOUGH THERE MAY BE SOME LINGERING
LIGHT PRECIPITATION ACROSS THE NORTH COUNTRY WEDNESDAY. PERHAPS THE
POTENTIAL FOR A TOUCH OF SUN WEDNESDAY MAY HELP TO GET TEMPERATURES
INTO THE UPPER 30S TO LOWER 40S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
A SIGNIFICANT STORM MAY BRING MUCH MORE IMPACTFUL WEATHER LATE NEXT
WEEK INTO THE WEEKEND BROUGHT ON BY A DIGGING UPPER LEVEL TROUGH
WHICH LOOKS TO TAKE ON A NEGATIVE TILT OVER THE GREAT LAKES. THERE
ARE STILL SOME DIFFERENCES MAINLY IN TIMING OF THE SURFACE LOW WITH
THE 12Z GFS ABOUT SIX HOURS FASTER THAN THE 12Z ECMWF BUT THERE IS
NOW SOME AGREEMENT IN THE TRACK SHIFTING SOMEWHERE OVER THE EASTERN
LAKES THURSDAY THROUGH FRIDAY. THE 12Z GFS SHOWS THE LOW CENTER
TRACKING JUST TO THE NORTHWEST OF THE LAKES WHILE THE 12Z ECMWF
SHOWS THE STORM TRACK ACROSS OUR FORECAST AREA ALONG THE I-90
CORRIDOR. THE GFS TRACK IS A CLIMATOLOGICALLY FAVORED TRACK FOR HIGH
WINDS WITH 12Z BUFKIT PROFILES SHOWING WIND GUSTS TO 50 OR 60 MPH
POSSIBLE ON FRIDAY ONCE THE SYSTEM SHIFTS TO OUR EAST AND COLD
ADVECTION HELPS MIX 60 TO 70 KT WINDS AT 850MB TO THE SURFACE. THE
ECMWF TRACK WOULD NOT BRING WINDS AS STRONG WITH THE CENTER SHIFTING
OVERHEAD.
AHEAD OF THIS POTENTIAL WIND IMPACT SOUTHERLY FLOW EAST OF THE
STORM SYSTEM WILL BRING WARM AIR AND INCREASING MOISTURE. FORECAST
HIGHS ON THURSDAY LOOK TO BE ABOVE NORMAL AVERAGING IN THE MID 40S
ACROSS INLAND AREAS AND UPPER 40S TO NEAR 50 ALONG THE LAKE SHORES
WITH A DOWNSLOPING SOUTHERLY WIND. WITH SUCH MILD TEMPERATURES ANY
CHANCE FOR PRECIPITATION WOULD COME IN THE FORM OF RAIN DURING THE
DAY. THURSDAY NIGHT WE SHOULD SEE A CHANGE TO A PERIOD OF COOLER
WEATHER AS THE UPPER LEVEL TROUGH SHIFTS OVER THE LOWER LAKES AND
THE SURFACE LOW CROSSES NEAR NEW YORK.
THE COOL DOWN CONTINUES FRIDAY INTO SATURDAY WITH BOTH MODELS
SHIFTING THE LOW EAST OR NORTH EAST OF THE FORECAST AREA. LIKELY
PROBABILITIES FOR WIDESPREAD SYNOPTIC SNOW AND GUSTY WINDS ARE ARE
INCLUDED IN THE FORECAST FOR FRIDAY WITH SURFACE TEMPERATURES ONLY
IN THE 30S. BOTH MODELS CONTINUE TO SHOW COLD AIR IN PLACE THROUGH
THE WEEKEND WITH WEST TO NORTHWEST WINDS OVER THE LAKES WHICH
FAVORS A SET UP FOR ACCUMULATING LAKE EFFECT SNOW DOWN WIND OF
THE LAKES OVER THE WEEKEND.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AT 18Z MVFR AND VFR FLIGHT CONDITIONS WERE FOUND ACROSS THE REGION
TO START THE TAF PACKAGE. TO OUR SOUTH THIS EARLY AFTERNOON AN AREA
OF LOW PRESSURE WAS FOUND OVER NORTHERN KENTUCKY WITH THE NORTHERN
SHIELD OF PRECIPITATION NOW REACHING INTO SOUTHERN OHIO AND NORTHERN
WEST VIRGINIA.
THIS SURFACE LOW WILL ADVANCE NORTHEASTWARD AND PASS JUST TO OUR
SOUTH OVERNIGHT ACROSS PENNSYLVANIA. TONIGHT WINDS WILL
DIMINISH...BUT FLOW FROM A NORTHEAST DIRECTION AS THE RAIN NEARS.
THIS LIGHT...BUT NORTHEAST FLOW IS CLIMATOLOGICALLY FAVORED FOR IFR
CIGS AND VSBYS AT ALL TAF SITES. HAVE LOWERED ALL TAF SITES INTO
IFR...AND POSSIBLY BRIEF LIFR WITH A PERIOD OF RAIN OVERNIGHT. AS
THE LOW ADVANCES EASTWARD TOWARDS LONG ISLAND EARLY TUESDAY MORNING
WINDS WILL SHIFT TO A NORTHWESTERLY FLOW AND ALLOW FOR SOME
IMPROVEMENT TOWARDS MVFR.
TOWARDS MORNING A DRY SLOT MAY END THE RAIN FIRST IN THE GENESEE
VALLEY...WITH A DEFORMATION BAND/UPSLOPE SHOWERS LINGERING ACROSS
WNY. AS THE LOW NEAR LI DEEPENS OUR DRY SLOT WILL ERODE WITH SHOWERS
RETURNING EASTWARD ACROSS THE GENESEE VALLEY AND NORTH COUNTRY.
EXPECT STILL MVFR FLIGHT CONDITIONS OVER MUCH OF THE TAF SITES
THROUGH EARLY AFTERNOON.
OUTLOOK...
TUESDAY AFTERNOON AND NIGHT...RAIN ENDING WITH SLOW IMPROVEMENT
BACK TO VFR.
WEDNESDAY...MAINLY VFR.
THURSDAY...DETERIORATING TO MVFR WITH SHOWERS LIKELY IN THE AFTERNOON.
THURSDAY NIGHT...MVFR WITH RAIN SHOWERS CHANGING TO SNOW. GUSTY
WINDS.
FRIDAY...IFR WITH SNOW LIKELY. GUSTY WINDS.
SATURDAY...MVFR/IFR SNOW SHOWERS LIKELY.
&&
.MARINE...
HAVE DROPPED THE SCA FOR THE EASTERN HALF OF LAKE ONTARIO AS WINDS
AND WAVES CONTINUE TO DIMINISH. WAVES WILL STILL NEAR 4 FEET THIS
MORNING ACROSS FAR NORTHEASTERN PORTIONS OF THE LAKE...BUT A
WEAKENING PRESSURE GRADIENT WILL ALLOW THESE WINDS AND WAVES TO
FURTHER DIMINISH THIS AFTERNOON.
WINDS WILL INCREASE AGAIN OUT OF THE NORTHWEST LATER TUESDAY BEHIND
ANOTHER AREA OF LOW PRESSURE. THIS MAY BRING SMALL CRAFT ADVISORY
CONDITIONS ONCE AGAIN...ESPECIALLY ON LAKE ONTARIO. THESE WINDS WILL
CONTINUE TUESDAY NIGHT BEFORE DIMINISHING ON WEDNESDAY.
A STRONGER STORM SYSTEM IS FORECAST TO MOVE INTO THE VICINITY OF THE
LOWER LAKES BY THURSDAY NIGHT AND FRIDAY. THIS MAY BRING A PERIOD OF
STRONGER WINDS...ALTHOUGH THE DETAILS REMAIN VERY UNCERTAIN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...APFFEL/THOMAS
NEAR TERM...APFFEL/THOMAS
SHORT TERM...TMA
LONG TERM...SMITH
AVIATION...THOMAS
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1024 AM EST MON DEC 17 2012
.SYNOPSIS...
CLOUDY SKIES WILL PREVAIL ACROSS THE REGION TODAY WITH RAIN
RETURNING LATE THIS AFTERNOON TO SOUTHWESTERN NEW YORK STATE. A LOW
WILL TRACK ACROSS PENNSYLVANIA AND INTO SOUTHERN NEW ENGLAND WHICH
WILL BRING A STEADY RAIN INTO THE REMAINDER OF THE REGION THIS
EVENING WITH RAIN LINGERING INTO TUESDAY. WARM TEMPERATURES WILL
CONTINUE THROUGH MUCH OF THE WEEK BEFORE A TURN TOWARDS COLDER AND
MORE WINTRY WEATHER BY FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS THIS LATE MORNING DISPLAY THE AREA OF RAIN/WINTRY
MIX NOW EXITING OUR CWA TO THE NORTH AND EAST. A LITTLE DRIZZLE MAY
LINGER ACROSS THE NORTH COUNTRY FOR ANOTHER HOUR...OTHERWISE WE WILL
HAVE A BRIEF DRY PERIOD BEFORE THE NEXT SYSTEM ARRIVES FROM THE OHIO
VALLEY.
SATELLITE IMAGERY THIS MORNING DISPLAYS PLENTY OF CLOUDS ACROSS THE
GREAT LAKES AND NORTHEAST REGION. BUFKIT SOUNDINGS OF THE NAM AND
GFS DISPLAY ABUNDANT MOISTURE IN THE LOWEST 5K FEET AND EXPECT
CLOUDY SKIES TO REMAIN THROUGH THE BULK OF THE DAY.
ANOTHER DAY OF MUCH ABOVE NORMAL TEMPERATURES TO MOST
LOCATIONS...WITH HIGHS NEAR OR ABOVE 50 ACROSS THE WESTERN TWO
THIRDS OF THE CWA. A DEVELOPING SOUTHWESTERLY FLOW MAY KEEP BUFFALO
FROM RISING MUCH ABOVE 50...BUT DOWNSLOPING WILL CONTINUE IN THE
GENESEE VALLEY AND FINGER LAKES REGIONS...WHERE TEMPERATURES SHOULD
REACH THE LOWER TO MID 50S.
AN UPPER LEVEL TROF AND ASSOCIATED SURFACE LOW WILL TRACK FROM THE
OHIO VALLEY AND INTO THE REGION TONIGHT. NAM BUFKIT INDICATES LIFT
WELL ALOFT ASSOCIATED WITH THE UPPER TROF...AS WELL AS WARM AIR
ADVECTION IN THE MID-LEVELS. GFS/RGEM/NAM AND SREF ENSEMBLES ARE IN
EXCELLENT AGREEMENT IN TERMS OF QPF...AND GIVEN THE LARGE-SCALE
NATURE OF THE PRECIPITATION HAVE A HIGH CONFIDENCE IN MEASURABLE
PRECIPITATION TONIGHT. NOTED THE 09Z HRRR AND THE 06Z RUN OF THE
NAM ARE A BIT SLOWER THAN PREVIOUS GUIDANCE...SO TRY TO BLEND THIS
SLOWER TIMING WITH FASTER MODELS SUCH AS THE GFS. USING THIS
APPROACH...EXPECT RAIN WILL SPREAD FROM SOUTH TO NORTH THIS
EVENING...LIKELY ENTERING WESTERN PORTIONS OF THE SOUTHERN TIER
AROUND OR JUST AFTER.
THIS SHOULD BE A FAIRLY SOAKING RAINFALL...BRINGING AN AVERAGE OF A
HALF INCH OF RAIN TO THE REGION TONIGHT. LOCALLY HIGHER AMOUNTS TO
AN INCH ARE POSSIBLE...WITH THE BEST CHANCE OF THIS IN LOCATIONS
EAST OF ROCHESTER. FORTUNATELY...WARMER AIR SHOULD BE IN PLACE BY
TONIGHT...WITH ALL PRECIPITATION LIKELY FALLING AS RAIN. EXPECT
FOG WILL DEVELOP IN SOME AREAS TONIGHT
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
WIDESPREAD STEADY RAIN WILL BE ACROSS THE AREA TUESDAY MORNING IN
AREA OF STRONG ISENTROPIC ASCENT AHEAD OF THE APPROACHING SURFACE
LOW. LATEST MODELS CONTINUING TO SUGGEST THAT THE LOW WILL REFORM
ALONG THE SOUTHERN NEW ENGLAND COAST DURING THE DAY TUESDAY AND MOVE
UP THE NEW ENGLAND COAST. AS THIS HAPPENS...COLDER AIR WILL BE DRAWN
INTO THE STATE TUESDAY AFTERNOON AND TUESDAY NIGHT. THIS SHOULD
RESULT IN A GRADUAL TRANSITION TO SOME SCATTERED LAKE/OROGRAPHICALLY
ENHANCED RAIN/SNOW SHOWERS WITH ALL SNOW BECOMING LIKELY OVER THE
HIGHER TERRAIN. ANY SNOW ACCUMULATIONS SHOULD BE LIMITED TO LESS
THAN 2 INCHES AND LIKELY CONFINED TO THE HIGHER TERRAIN TUESDAY
NIGHT.
BUILDING HEIGHTS EXPECTED ON WEDNESDAY IN RESPONSE TO STRONG
SHORTWAVE MOVING ACROSS THE FOUR CORNERS REGION. WEAK SURFACE RIDGE
BUILDING ACROSS THE REGION SHOULD BRING MAINLY QUIET WEATHER
WEDNESDAY AND WEDNESDAY NIGHT...ALTHOUGH THERE MAY BE SOME LINGERING
LIGHT PRECIPITATION ACROSS THE NORTH COUNTRY WEDNESDAY. PERHAPS THE
POTENTIAL FOR A TOUCH OF SUN WEDNESDAY MAY HELP TO GET TEMPERATURES
INTO THE UPPER 30S TO LOWER 40S.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A SIGNIFICANT STORM MAY BRING MUCH MORE IMPACTFUL WEATHER LATE NEXT
WEEK INTO THE WEEKEND BROUGHT ON BY A DIGGING UPPER LEVEL TROUGH
WHICH LOOKS TO TAKE ON A NEGATIVE TILT OVER THE GREAT LAKES. THERE
ARE STILL SOME DIFFERENCES MAINLY IN TIMING OF THE SURFACE LOW WITH
THE 12Z GFS ABOUT SIX HOURS FASTER THAN THE 12Z ECMWF BUT THERE IS
NOW SOME AGREEMENT IN THE TRACK SHIFTING SOMEWHERE OVER THE EASTERN
LAKES THURSDAY THROUGH FRIDAY. THE 12Z GFS SHOWS THE LOW CENTER
TRACKING JUST TO THE NORTHWEST OF THE LAKES WHILE THE 12Z ECMWF
SHOWS THE STORM TRACK ACROSS OUR FORECAST AREA ALONG THE I-90
CORRIDOR. THE GFS TRACK IS A CLIMATOLOGICALLY FAVORED TRACK FOR HIGH
WINDS WITH 12Z BUFKIT PROFILES SHOWING WIND GUSTS TO 50 OR 60 MPH
POSSIBLE ON FRIDAY ONCE THE SYSTEM SHIFTS TO OUR EAST AND COLD
ADVECTION HELPS MIX 60 TO 70 KT WINDS AT 850MB TO THE SURFACE. THE
ECMWF TRACK WOULD NOT BRING WINDS AS STRONG WITH THE CENTER SHIFTING
OVERHEAD.
AHEAD OF THIS POTENTIAL WIND IMPACT SOUTHERLY FLOW EAST OF THE
STORM SYSTEM WILL BRING WARM AIR AND INCREASING MOISTURE. FORECAST
HIGHS ON THURSDAY LOOK TO BE ABOVE NORMAL AVERAGING IN THE MID 40S
ACROSS INLAND AREAS AND UPPER 40S TO NEAR 50 ALONG THE LAKE SHORES
WITH A DOWNSLOPING SOUTHERLY WIND. WITH SUCH MILD TEMPERATURES ANY
CHANCE FOR PRECIPITATION WOULD COME IN THE FORM OF RAIN DURING THE
DAY. THURSDAY NIGHT WE SHOULD SEE A CHANGE TO A PERIOD OF COOLER
WEATHER AS THE UPPER LEVEL TROUGH SHIFTS OVER THE LOWER LAKES AND
THE SURFACE LOW CROSSES NEAR NEW YORK.
THE COOL DOWN CONTINUES FRIDAY INTO SATURDAY WITH BOTH MODELS
SHIFTING THE LOW EAST OR NORTH EAST OF THE FORECAST AREA. LIKELY
PROBABILITIES FOR WIDESPREAD SYNOPTIC SNOW AND GUSTY WINDS ARE ARE
INCLUDED IN THE FORECAST FOR FRIDAY WITH SURFACE TEMPERATURES ONLY
IN THE 30S. BOTH MODELS CONTINUE TO SHOW COLD AIR IN PLACE THROUGH
THE WEEKEND WITH WEST TO NORTHWEST WINDS OVER THE LAKES WHICH
FAVORS A SET UP FOR ACCUMULATING LAKE EFFECT SNOW DOWN WIND OF
THE LAKES OVER THE WEEKEND.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
AN AREA OF RAIN WILL LIFT NORTHEAST AND OUT OF THE REGION THROUGH
MID-MORNING...WITH OTHERWISE DRY CONDITIONS ACROSS THE REGION.
CIGS WILL BE THE MAIN CONCERN FOR TODAY. FOR THE MOST
PART...EXPECT EITHER VFR OR MVFR CONDITIONS TODAY. THE EXCEPTION TO
THIS IS JHW...WHERE FOG AND CIGS BLO 1000 FEET SHOULD LINGER
THROUGH MUCH OF THIS MORNING BEFORE FINALLY LIFTING. CONFIDENCE IS
MODERATE TO LOW IN TIMING OF THIS.
RAIN WILL SPREAD INTO THE REGION THIS EVENING...WITH CONDITIONS
EXPECTED TO LOWER TO IFR AS THE FLOW BECOMES MORE NE AND THEN NW.
OUTLOOK...
TUESDAY...WIDESPREAD IFR WITH RAIN.
WEDNESDAY...MAINLY VFR.
THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
THURSDAY NIGHT...MVFR WITH A CHANCE OF SHOWERS. GUSTY WINDS.
FRIDAY...MVFR/IFR WITH A CHANCE OF SNOW. GUSTY WINDS.
&&
.MARINE...
HAVE DROPPED THE SCA FOR THE EASTERN HALF OF LAKE ONTARIO AS WINDS
AND WAVES CONTINUE TO DIMINISH. WAVES WILL STILL NEAR 4 FEET THIS
MORNING ACROSS FAR NORTHEASTERN PORTIONS OF THE LAKE...BUT A
WEAKENING PRESSURE GRADIENT WILL ALLOW THESE WINDS AND WAVES TO
FURTHER DIMINISH THIS AFTERNOON.
WINDS WILL INCREASE AGAIN OUT OF THE NORTHWEST LATER TUESDAY BEHIND
ANOTHER AREA OF LOW PRESSURE. THIS MAY BRING SMALL CRAFT ADVISORY
CONDITIONS ONCE AGAIN...ESPECIALLY ON LAKE ONTARIO. THESE WINDS WILL
CONTINUE TUESDAY NIGHT BEFORE DIMINISHING ON WEDNESDAY.
A STRONGER STORM SYSTEM IS FORECAST TO MOVE INTO THE VICINITY OF THE
LOWER LAKES BY THURSDAY NIGHT AND FRIDAY. THIS MAY BRING A PERIOD OF
STRONGER WINDS...ALTHOUGH THE DETAILS REMAIN VERY UNCERTAIN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...APFFEL/THOMAS
NEAR TERM...APFFEL/THOMAS
SHORT TERM...TMA
LONG TERM...SMITH
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
725 AM EST MON DEC 17 2012
.SYNOPSIS...
WEAKENING LOW PRESSURE WILL LIFT INTO CANADA TODAY...WITH LINGERING
SHOWERS TAPERING OFF. ANOTHER LOW WILL TRACK ACROSS PENNSYLVANIA AND
INTO SOUTHERN NEW ENGLAND WHICH WILL BRING A STEADY RAIN TO THE
REGION THIS EVENING AND INTO TUESDAY. WARM TEMPERATURES WILL
CONTINUE THROUGH MUCH OF THE WEEK BEFORE A TURN TOWARDS COLDER AND
MORE WINTRY WEATHER BY FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 700 AM...RADAR SHOWS A FAIRLY LARGE AREA OF STEADY RAIN ACROSS
LEWIS AND JEFFERSON COUNTIES. THIS WILL LIFT NORTHEAST OF THE CWA
THROUGH MID-MORNING. NEARBY MESONET SITES REPORT TEMPERATURES
CLOSE TO FREEZING...SO PATCHY AREAS OF FREEZING RAIN STILL CAN/T
BE RULED OUT EVEN THOUGH THE MAJORITY OF PRECIPITATION IS FALLING
AS RAIN. ANY THREATS OF ICING WILL END BY MID-MORNING AS THE RAIN
ENDS AND TEMPERATURES RISE ABOVE FREEZING.
ONCE THIS SHORTWAVE AND WEAK FRONTAL BOUNDARY EXIT THIS
MORNING...EXPECT A DRY PERIOD ACROSS MUCH OF WESTERN NEW YORK FOR
MUCH OF THE DAYLIGHT HOURS. BUFKIT SOUNDINGS SUGGEST THERE IS A
LIMITED OPPORTUNITY FOR SOME BREAKS OF SUNSHINE THIS MORNING AND
EARLY AFTERNOON...AS MOISTURE THINS OUT. THIS WILL BRING ANOTHER
DAY OF MUCH ABOVE NORMAL TEMPERATURES TO MOST LOCATIONS...WITH
HIGHS NEAR OR ABOVE 50 ACROSS THE WESTERN TWO THIRDS OF THE CWA. A
DEVELOPING SOUTHWESTERLY FLOW MAY KEEP BUFFALO FROM RISING MUCH
ABOVE 50...BUT DOWNSLOPING WILL CONTINUE IN THE GENESEE VALLEY AND
FINGER LAKES REGIONS...WHERE TEMPERATURES SHOULD REACH THE LOWER
TO MID 50S.
AN UPPER LEVEL TROF AND ASSOCIATED SURFACE LOW WILL TRACK FROM THE
OHIO VALLEY AND INTO THE REGION TONIGHT. NAM BUFKIT INDICATES LIFT
WELL ALOFT ASSOCIATED WITH THE UPPER TROF...AS WELL AS WARM AIR
ADVECTION IN THE MID-LEVELS. GFS/RGEM/NAM AND SREF ENSEMBLES ARE IN
EXCELLENT AGREEMENT IN TERMS OF QPF...AND GIVEN THE LARGE-SCALE
NATURE OF THE PRECIPITATION HAVE A HIGH CONFIDENCE IN MEASURABLE
PRECIPITATION TONIGHT. NOTED THE 09Z HRRR AND THE 06Z RUN OF THE
NAM ARE A BIT SLOWER THAN PREVIOUS GUIDANCE...SO TRY TO BLEND THIS
SLOWER TIMING WITH FASTER MODELS SUCH AS THE GFS. USING THIS
APPROACH...EXPECT RAIN WILL SPREAD FROM SOUTH TO NORTH THIS
EVENING...LIKELY ENTERING WESTERN PORTIONS OF THE SOUTHERN TIER
AROUND OR JUST AFTER.
THIS SHOULD BE A FAIRLY SOAKING RAINFALL...BRINGING AN AVERAGE OF A
HALF INCH OF RAIN TO THE REGION TONIGHT. LOCALLY HIGHER AMOUNTS TO
AN INCH ARE POSSIBLE...WITH THE BEST CHANCE OF THIS IN LOCATIONS
EAST OF ROCHESTER. FORTUNATELY...WARMER AIR SHOULD BE IN PLACE BY
TONIGHT...WITH ALL PRECIPITATION LIKELY FALLING AS RAIN. EXPECT
FOG WILL DEVELOP IN SOME AREAS TONIGHT
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
WIDESPREAD STEADY RAIN WILL BE ACROSS THE AREA TUESDAY MORNING IN
AREA OF STRONG ISENTROPIC ASCENT AHEAD OF THE APPROACHING SURFACE
LOW. LATEST MODELS CONTINUING TO SUGGEST THAT THE LOW WILL REFORM
ALONG THE SOUTHERN NEW ENGLAND COAST DURING THE DAY TUESDAY AND MOVE
UP THE NEW ENGLAND COAST. AS THIS HAPPENS...COLDER AIR WILL BE DRAWN
INTO THE STATE TUESDAY AFTERNOON AND TUESDAY NIGHT. THIS SHOULD
RESULT IN A GRADUAL TRANSITION TO SOME SCATTERED LAKE/OROGRAPHICALLY
ENHANCED RAIN/SNOW SHOWERS WITH ALL SNOW BECOMING LIKELY OVER THE
HIGHER TERRAIN. ANY SNOW ACCUMULATIONS SHOULD BE LIMITED TO LESS
THAN 2 INCHES AND LIKELY CONFINED TO THE HIGHER TERRAIN TUESDAY
NIGHT.
BUILDING HEIGHTS EXPECTED ON WEDNESDAY IN RESPONSE TO STRONG
SHORTWAVE MOVING ACROSS THE FOUR CORNERS REGION. WEAK SURFACE RIDGE
BUILDING ACROSS THE REGION SHOULD BRING MAINLY QUIET WEATHER
WEDNESDAY AND WEDNESDAY NIGHT...ALTHOUGH THERE MAY BE SOME LINGERING
LIGHT PRECIPITATION ACROSS THE NORTH COUNTRY WEDNESDAY. PERHAPS THE
POTENTIAL FOR A TOUCH OF SUN WEDNESDAY MAY HELP TO GET TEMPERATURES
INTO THE UPPER 30S TO LOWER 40S.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A SIGNIFICANT STORM MAY BRING MUCH MORE IMPACTFUL WEATHER LATE NEXT
WEEK INTO THE WEEKEND BROUGHT ON BY A DIGGING UPPER LEVEL TROUGH
WHICH LOOKS TO TAKE ON A NEGATIVE TILT OVER THE GREAT LAKES. THERE
ARE STILL SOME DIFFERENCES MAINLY IN TIMING OF THE SURFACE LOW WITH
THE 12Z GFS ABOUT SIX HOURS FASTER THAN THE 12Z ECMWF BUT THERE IS
NOW SOME AGREEMENT IN THE TRACK SHIFTING SOMEWHERE OVER THE EASTERN
LAKES THURSDAY THROUGH FRIDAY. THE 12Z GFS SHOWS THE LOW CENTER
TRACKING JUST TO THE NORTHWEST OF THE LAKES WHILE THE 12Z ECMWF
SHOWS THE STORM TRACK ACROSS OUR FORECAST AREA ALONG THE I-90
CORRIDOR. THE GFS TRACK IS A CLIMATOLOGICALLY FAVORED TRACK FOR HIGH
WINDS WITH 12Z BUFKIT PROFILES SHOWING WIND GUSTS TO 50 OR 60 MPH
POSSIBLE ON FRIDAY ONCE THE SYSTEM SHIFTS TO OUR EAST AND COLD
ADVECTION HELPS MIX 60 TO 70 KT WINDS AT 850MB TO THE SURFACE. THE
ECMWF TRACK WOULD NOT BRING WINDS AS STRONG WITH THE CENTER SHIFTING
OVERHEAD.
AHEAD OF THIS POTENTIAL WIND IMPACT SOUTHERLY FLOW EAST OF THE
STORM SYSTEM WILL BRING WARM AIR AND INCREASING MOISTURE. FORECAST
HIGHS ON THURSDAY LOOK TO BE ABOVE NORMAL AVERAGING IN THE MID 40S
ACROSS INLAND AREAS AND UPPER 40S TO NEAR 50 ALONG THE LAKE SHORES
WITH A DOWNSLOPING SOUTHERLY WIND. WITH SUCH MILD TEMPERATURES ANY
CHANCE FOR PRECIPITATION WOULD COME IN THE FORM OF RAIN DURING THE
DAY. THURSDAY NIGHT WE SHOULD SEE A CHANGE TO A PERIOD OF COOLER
WEATHER AS THE UPPER LEVEL TROUGH SHIFTS OVER THE LOWER LAKES AND
THE SURFACE LOW CROSSES NEAR NEW YORK.
THE COOL DOWN CONTINUES FRIDAY INTO SATURDAY WITH BOTH MODELS
SHIFTING THE LOW EAST OR NORTH EAST OF THE FORECAST AREA. LIKELY
PROBABILITIES FOR WIDESPREAD SYNOPTIC SNOW AND GUSTY WINDS ARE ARE
INCLUDED IN THE FORECAST FOR FRIDAY WITH SURFACE TEMPERATURES ONLY
IN THE 30S. BOTH MODELS CONTINUE TO SHOW COLD AIR IN PLACE THROUGH
THE WEEKEND WITH WEST TO NORTHWEST WINDS OVER THE LAKES WHICH
FAVORS A SET UP FOR ACCUMULATING LAKE EFFECT SNOW DOWN WIND OF
THE LAKES OVER THE WEEKEND.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AN AREA OF RAIN WILL LIFT NORTHEAST AND OUT OF THE REGION THROUGH
MID-MORNING...WITH OTHERWISE DRY CONDITIONS ACROSS THE REGION.
CIGS WILL BE THE MAIN CONCERN FOR TODAY. FOR THE MOST
PART...EXPECT EITHER VFR OR MVFR CONDITIONS TODAY. THE EXCEPTION TO
THIS IS JHW...WHERE FOG AND CIGS BLO 1000 FEET SHOULD LINGER
THROUGH MUCH OF THIS MORNING BEFORE FINALLY LIFTING. CONFIDENCE IS
MODERATE TO LOW IN TIMING OF THIS.
RAIN WILL SPREAD INTO THE REGION THIS EVENING...WITH CONDITIONS
EXPECTED TO LOWER TO IFR AS THE FLOW BECOMES MORE NE AND THEN NW.
OUTLOOK...
TUESDAY...WIDESPREAD IFR WITH RAIN.
WEDNESDAY...MAINLY VFR.
THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
THURSDAY NIGHT...MVFR WITH A CHANCE OF SHOWERS. GUSTY WINDS.
FRIDAY...MVFR/IFR WITH A CHANCE OF SNOW. GUSTY WINDS.
&&
.MARINE...
MODERATE SOUTHERLY WINDS WILL TAPER OFF THROUGH THIS MORNING. THIS
WILL MAINTAIN SMALL CRAFT ADVISORY CONDITIONS AT THE NORTHEAST END
OF LAKE ONTARIO THROUGH THIS MORNING. THE PRESSURE GRADIENT WILL
RELAX ACROSS THE AREA THIS AFTERNOON...ALLOWING WINDS TO DIMINISH.
WINDS WILL INCREASE AGAIN OUT OF THE NORTHWEST LATER TUESDAY BEHIND
ANOTHER AREA OF LOW PRESSURE. THIS MAY BRING SMALL CRAFT ADVISORY
CONDITIONS ONCE AGAIN...ESPECIALLY ON LAKE ONTARIO. THESE WINDS WILL
CONTINUE TUESDAY NIGHT BEFORE DIMINISHING ON WEDNESDAY.
A STRONGER STORM SYSTEM IS FORECAST TO MOVE INTO THE VICINITY OF THE
LOWER LAKES BY THURSDAY NIGHT AND FRIDAY. THIS MAY BRING A PERIOD OF
STRONGER WINDS...ALTHOUGH THE DETAILS REMAIN VERY UNCERTAIN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR LOZ044-
045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...TMA
LONG TERM...SMITH
AVIATION...APFFEL
MARINE...APFFEL/TMA
AREA FORECAST DISCUSSION
NWS BUFFALO NY
640 AM EST MON DEC 17 2012
.SYNOPSIS...
WEAKENING LOW PRESSURE WILL LIFT INTO CANADA TODAY...WITH LINGERING
SHOWERS TAPERING OFF. ANOTHER LOW WILL TRACK ACROSS PENNSYLVANIA AND
INTO SOUTHERN NEW ENGLAND WHICH WILL BRING A STEADY RAIN TO THE
REGION THIS EVENING AND INTO TUESDAY. WARM TEMPERATURES WILL
CONTINUE THROUGH MUCH OF THE WEEK BEFORE A TURN TOWARDS COLDER AND
MORE WINTRY WEATHER BY FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 600 AM...RADAR SHOWS A FAIRLY LARGE AREA OF STEADY RAIN EAST OF
LAKE ONTARIO. MODEL GUIDANCE HAS NOT HAD A VERY GOOD HANDLE ON
THIS...WITH SEVERAL OF THE 00Z MODELS STRUGGLING TO HANDLE A
SHORTWAVE WHICH IS MOVING ACROSS A WEAK SURFACE BOUNDARY AND
ASSOCIATED TROF. THE 00Z RGEM AND THE 04Z HRRR DO CAPTURE THIS
FAIRLY WELL...AND PROVIDE FAIRLY GOOD GUIDANCE THROUGH THE EARLY
MORNING HOURS. FOLLOWING THIS...EXPECT THIS AREA TO LIFT OUT OF
THE CWA AROUND MID-MORNING.
THERE CONTINUES TO BE ONE LINGERING AREA OF CONCERN ACROSS LEWIS
COUNTY EARLY THIS MORNING. AIR TO THE NORTH AND EAST OF OUR CWA IS
CONSIDERABLY COOLER. THE VAST MAJORITY OF OBSERVATIONS FROM AND
AROUND LEWIS COUNTY ARE REPORTING TEMPERATURES IN THE MID TO UPPER
30S...BUT THERE STILL MAY BE A FEW SPOTS NEAR FREEZING. SOUNDINGS
SUGGEST ANY AREAS BELOW FREEZING WOULD GET FREEZING RAIN. BECAUSE
OF THE ISOLATED NATURE OF SUB- FREEZING TEMPERATURES...WILL NOT
ISSUE AN ADVISORY...BUT WILL HIGHLIGHT THE POTENTIAL IN AN SPS
PRODUCT. TEMPERATURES WILL SLOWLY RISE EAST OF LAKE ONTARIO
TODAY...WITH HIGHS FROM AROUND 40 TO THE UPPER 40S...WITH THE
COOLEST TEMPERATURES REMAINING ACROSS LEWIS COUNTY.
ONCE THIS SHORTWAVE AND WEAK FRONTAL BOUNDARY EXIT TO THE NORTHEAST
THIS MORNING...EXPECT A DRY PERIOD ACROSS MUCH OF WESTERN NEW YORK
FOR MUCH OF THE DAYLIGHT HOURS. OUTSIDE OF LINGERING LOW LEVEL
MOISTURE IN THE SOUTHERN TIER...BUFKIT SOUNDINGS SUGGEST EVEN AN
OPPORTUNITY FOR SOME BREAKS OF SUNSHINE LATE THIS MORNING AND EARLY
AFTERNOON...AS MOISTURE THINS OUT. THIS WILL BRING ANOTHER DAY OF
MUCH ABOVE NORMAL TEMPERATURES TO MOST LOCATIONS...WITH HIGHS NEAR
OR ABOVE 50 ACROSS THE WESTERN TWO THIRDS OF THE CWA. A DEVELOPING
SOUTHWESTERLY FLOW MAY KEEP BUFFALO FROM RISING MUCH ABOVE 50...BUT
DOWNSLOPING WILL CONTINUE IN THE GENESEE VALLEY AND FINGER LAKES
REGIONS...WHERE TEMPERATURES SHOULD REACH THE LOWER TO MID 50S.
AN UPPER LEVEL TROF AND ASSOCIATED SURFACE LOW WILL TRACK FROM THE
OHIO VALLEY AND INTO THE REGION TONIGHT. NAM BUFKIT INDICATES LIFT
WELL ALOFT ASSOCIATED WITH THE UPPER TROF...AS WELL AS WARM AIR
ADVECTION IN THE MID-LEVELS. GFS/RGEM/NAM AND SREF ENSEMBLES ARE IN
EXCELLENT AGREEMENT IN TERMS OF QPF...AND GIVEN THE LARGE-SCALE
NATURE OF THE PRECIPITATION HAVE A HIGH CONFIDENCE IN MEASURABLE
PRECIPITATION TONIGHT. RAIN WILL SPREAD FROM SOUTH TO NORTH THIS
EVENING...LIKELY ENTERING WESTERN PORTIONS OF THE SOUTHERN TIER JUST
AROUND SUNSET.
THIS SHOULD BE A FAIRLY SOAKING RAINFALL...BRINGING AN AVERAGE OF A
HALF INCH OF RAIN TO THE REGION TONIGHT. LOCALLY HIGHER AMOUNTS TO
AN INCH ARE POSSIBLE...WITH THE BEST CHANCE OF THIS IN LOCATIONS
EAST OF ROCHESTER. FORTUNATELY...WARMER AIR SHOULD BE IN PLACE BY
TONIGHT...WITH ALL PRECIPITATION LIKELY FALLING AS RAIN.
EXPECT SOME PATCHY FOG EARLY THIS MORNING IN THE VALLEYS OF THE
SOUTHERN TIER...WITH A BIT MORE WIDESPREAD FOG POSSIBLE TONIGHT.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
WIDESPREAD STEADY RAIN WILL BE ACROSS THE AREA TUESDAY MORNING IN
AREA OF STRONG ISENTROPIC ASCENT AHEAD OF THE APPROACHING SURFACE
LOW. LATEST MODELS CONTINUING TO SUGGEST THAT THE LOW WILL REFORM
ALONG THE SOUTHERN NEW ENGLAND COAST DURING THE DAY TUESDAY AND MOVE
UP THE NEW ENGLAND COAST. AS THIS HAPPENS...COLDER AIR WILL BE DRAWN
INTO THE STATE TUESDAY AFTERNOON AND TUESDAY NIGHT. THIS SHOULD
RESULT IN A GRADUAL TRANSITION TO SOME SCATTERED LAKE/OROGRAPHICALLY
ENHANCED RAIN/SNOW SHOWERS WITH ALL SNOW BECOMING LIKELY OVER THE
HIGHER TERRAIN. ANY SNOW ACCUMULATIONS SHOULD BE LIMITED TO LESS
THAN 2 INCHES AND LIKELY CONFINED TO THE HIGHER TERRAIN TUESDAY
NIGHT.
BUILDING HEIGHTS EXPECTED ON WEDNESDAY IN RESPONSE TO STRONG
SHORTWAVE MOVING ACROSS THE FOUR CORNERS REGION. WEAK SURFACE RIDGE
BUILDING ACROSS THE REGION SHOULD BRING MAINLY QUIET WEATHER
WEDNESDAY AND WEDNESDAY NIGHT...ALTHOUGH THERE MAY BE SOME LINGERING
LIGHT PRECIPITATION ACROSS THE NORTH COUNTRY WEDNESDAY. PERHAPS THE
POTENTIAL FOR A TOUCH OF SUN WEDNESDAY MAY HELP TO GET TEMPERATURES
INTO THE UPPER 30S TO LOWER 40S.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A SIGNIFICANT STORM MAY BRING MUCH MORE IMPACTFUL WEATHER LATE NEXT
WEEK INTO THE WEEKEND BROUGHT ON BY A DIGGING UPPER LEVEL TROUGH
WHICH LOOKS TO TAKE ON A NEGATIVE TILT OVER THE GREAT LAKES. THERE
ARE STILL SOME DIFFERENCES MAINLY IN TIMING OF THE SURFACE LOW WITH
THE 12Z GFS ABOUT SIX HOURS FASTER THAN THE 12Z ECMWF BUT THERE IS
NOW SOME AGREEMENT IN THE TRACK SHIFTING SOMEWHERE OVER THE EASTERN
LAKES THURSDAY THROUGH FRIDAY. THE 12Z GFS SHOWS THE LOW CENTER
TRACKING JUST TO THE NORTHWEST OF THE LAKES WHILE THE 12Z ECMWF
SHOWS THE STORM TRACK ACROSS OUR FORECAST AREA ALONG THE I-90
CORRIDOR. THE GFS TRACK IS A CLIMATOLOGICALLY FAVORED TRACK FOR HIGH
WINDS WITH 12Z BUFKIT PROFILES SHOWING WIND GUSTS TO 50 OR 60 MPH
POSSIBLE ON FRIDAY ONCE THE SYSTEM SHIFTS TO OUR EAST AND COLD
ADVECTION HELPS MIX 60 TO 70 KT WINDS AT 850MB TO THE SURFACE. THE
ECMWF TRACK WOULD NOT BRING WINDS AS STRONG WITH THE CENTER SHIFTING
OVERHEAD.
AHEAD OF THIS POTENTIAL WIND IMPACT SOUTHERLY FLOW EAST OF THE
STORM SYSTEM WILL BRING WARM AIR AND INCREASING MOISTURE. FORECAST
HIGHS ON THURSDAY LOOK TO BE ABOVE NORMAL AVERAGING IN THE MID 40S
ACROSS INLAND AREAS AND UPPER 40S TO NEAR 50 ALONG THE LAKE SHORES
WITH A DOWNSLOPING SOUTHERLY WIND. WITH SUCH MILD TEMPERATURES ANY
CHANCE FOR PRECIPITATION WOULD COME IN THE FORM OF RAIN DURING THE
DAY. THURSDAY NIGHT WE SHOULD SEE A CHANGE TO A PERIOD OF COOLER
WEATHER AS THE UPPER LEVEL TROUGH SHIFTS OVER THE LOWER LAKES AND
THE SURFACE LOW CROSSES NEAR NEW YORK.
THE COOL DOWN CONTINUES FRIDAY INTO SATURDAY WITH BOTH MODELS
SHIFTING THE LOW EAST OR NORTH EAST OF THE FORECAST AREA. LIKELY
PROBABILITIES FOR WIDESPREAD SYNOPTIC SNOW AND GUSTY WINDS ARE ARE
INCLUDED IN THE FORECAST FOR FRIDAY WITH SURFACE TEMPERATURES ONLY
IN THE 30S. BOTH MODELS CONTINUE TO SHOW COLD AIR IN PLACE THROUGH
THE WEEKEND WITH WEST TO NORTHWEST WINDS OVER THE LAKES WHICH
FAVORS A SET UP FOR ACCUMULATING LAKE EFFECT SNOW DOWN WIND OF
THE LAKES OVER THE WEEKEND.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AN AREA OF RAIN WILL LIFT NORTHEAST AND OUT OF THE REGION THROUGH
MID-MORNING...WITH OTHERWISE DRY CONDITIONS ACROSS THE REGION.
CIGS WILL BE THE MAIN CONCERN FOR TODAY. FOR THE MOST
PART...EXPECT EITHER VFR OR MVFR CONDITIONS TODAY. THE EXCEPTION TO
THIS IS JHW...WHERE FOG AND CIGS BLO 1000 FEET SHOULD LINGER
THROUGH MUCH OF THIS MORNING BEFORE FINALLY LIFTING. CONFIDENCE IS
MODERATE TO LOW IN TIMING OF THIS.
RAIN WILL SPREAD INTO THE REGION THIS EVENING...WITH CONDITIONS
EXPECTED TO LOWER TO IFR AS THE FLOW BECOMES MORE NE AND THEN NW.
OUTLOOK...
TUESDAY...WIDESPREAD IFR WITH RAIN.
WEDNESDAY...MAINLY VFR.
THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
THURSDAY NIGHT...MVFR WITH A CHANCE OF SHOWERS. GUSTY WINDS.
FRIDAY...MVFR/IFR WITH A CHANCE OF SNOW. GUSTY WINDS.
&&
.MARINE...
MODERATE SOUTHERLY WINDS WILL TAPER OFF THROUGH THIS MORNING. THIS
WILL MAINTAIN SMALL CRAFT ADVISORY CONDITIONS AT THE NORTHEAST END
OF LAKE ONTARIO THROUGH THIS MORNING. THE PRESSURE GRADIENT WILL
RELAX ACROSS THE AREA THIS AFTERNOON...ALLOWING WINDS TO DIMINISH.
WINDS WILL INCREASE AGAIN OUT OF THE NORTHWEST LATER TUESDAY BEHIND
ANOTHER AREA OF LOW PRESSURE. THIS MAY BRING SMALL CRAFT ADVISORY
CONDITIONS ONCE AGAIN...ESPECIALLY ON LAKE ONTARIO. THESE WINDS WILL
CONTINUE TUESDAY NIGHT BEFORE DIMINISHING ON WEDNESDAY.
A STRONGER STORM SYSTEM IS FORECAST TO MOVE INTO THE VICINITY OF THE
LOWER LAKES BY THURSDAY NIGHT AND FRIDAY. THIS MAY BRING A PERIOD OF
STRONGER WINDS...ALTHOUGH THE DETAILS REMAIN VERY UNCERTAIN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR LOZ044-
045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...TMA
LONG TERM...SMITH
AVIATION...APFFEL
MARINE...APFFEL/TMA
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
415 PM EST MON DEC 17 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEAST THROUGH THE REGION THIS EVENING. HIGH
PRESSURE WILL BUILD IN FOR TUESDAY AND WEDNESDAY. A STRONG COLD
FRONT WILL SWEEP THROUGH THE AREA ON THURSDAY...BRINGING
PRECIPITATION AND WINDY CONDITIONS.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AN AREA OF LOW PRESSURE WILL CONTINUE TRACKING NORTHEAST THROUGH
THE ILN CWA THIS EVENING...EVENTUALLY MOVING INTO PENNSYLVANIA AS
A SURFACE COLD FRONT BEGINS ITS PROGRESSION THROUGH THE REGION. ON
THE SOUTH SIDE OF THIS BOUNDARY...WEAK SURFACE BASED INSTABILITY
HAS BEEN ABLE TO JUST NUDGE INTO THE FAR SOUTHERN ILN
COUNTIES...WITH SOME ELEVATED INSTABILITY EXTENDING THROUGH THE
SOUTHERN 1/3 TO 1/2 OF THE CWA. ATMOSPHERIC TEMPERATURE LEVELS ARE
QUITE LOW COMPARED TO A MORE TYPICAL SPRING OR SUMMER SEVERE
EVENT...WHICH HAS FAVORED THE PRODUCTION OF LARGE AMOUNTS OF SMALL
HAIL. MOST OF THE STORMS HAVE STRUGGLED TO GROW TALL ENOUGH TO
GENERATE LARGE HAIL...EVEN AS SHEAR SEEMS SUFFICIENT TO SUPPORT
SOME ORGANIZATION.
A WEAKENING TREND IS EXPECTED TONIGHT...BUT WITH RAP AND NAM12
RUNS INDICATING SOME WEAK INSTABILITY WILL PERSIST IN SOUTHERN
OHIO / NORTHEAST KENTUCKY FOR SEVERAL HOURS. SO...THUNDER WILL BE
KEPT IN THE FORECAST. IN ADDITION...CATEGORICAL POPS WILL BE USED
AS EXTRAPOLATED FROM THE CURRENT BAND OF PRECIPITATION...BEFORE
TAPERING TO LIKELY OVERNIGHT AS THE FORCING MOVES FURTHER AWAY.
NEAR THE BASE OF THE MID-LEVEL TROUGH...AND ON THE BACK SIDE OF
THE SURFACE LOW...ADDITIONAL (GENERALLY LIGHT) PRECIPITATION IS
EXPECTED TO CONTINUE OVERNIGHT ON A WSW-ENE AXIS ACROSS THE
NORTHERN PORTIONS OF THE CWA. TEMPERATURES WILL BE COOLING DOWN
JUST ENOUGH TO ALLOW FOR A WET MIX OF RAIN AND SNOW NEAR THE END
OF THE PRECIPITATION. NO ACCUMULATIONS ARE EXPECTED.
COLD ADVECTION WILL HELP TEMPS APPROACH FREEZING IN THE NORTHWEST
CWA OVERNIGHT...WITH A GRADIENT THAT EXTENDS TO THE LOWER 40S IN
THE SOUTHEAST CORNER.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
THE SURFACE PRESSURE PATTERN WILL REMAIN COMPLICATED THROUGH THE
SHORT TERM...AS A NARROW RIDGE OF HIGH PRESSURE BUILDS IN
TUESDAY...BEFORE LOW PRESSURE MOVES EAST THROUGH THE SOUTHERN
GREAT LAKES TUESDAY NIGHT. IN THE MID LEVELS...A RIDGE WILL BUILD
OVER THE OHIO VALLEY AND SOUTHERN STATES THROUGH WEDNESDAY. DRY
WEATHER WILL CHARACTERIZE THE PERIOD...WITH FLOW REMAINING
GENERALLY SOUTHWESTERLY. TEMPERATURES WILL INCREASE A BIT FROM
TUESDAY TO WEDNESDAY...ESPECIALLY IN THE SOUTHERN COUNTIES. ON THE
OTHER HAND...LIGHTER WINDS AND CLEARING SKIES SHOULD MAKE TUESDAY
NIGHT COOLER THAN MONDAY NIGHT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
FOR THE PERIOD WEDNESDAY NIGHT INTO THURSDAY NIGHT...A DEEPENING MID
LEVEL TROF AND DEEPENING SFC LOW PRESSURE SYSTEM WILL PULL NORTHEAST
FROM THE SRN PLAINS TO THE GREAT LAKES/OHIO VALLEY REGION. THE TRACK
OF THE SFC LOW CONTINUES TO BE NW OF THE REGION...SO ANY MAJOR
WINTER WEATHER WILL STAY TO OUR NW. THE LOW WILL BE ASSOCIATED WITH
A STRONG COLD FRONT. DEEP MOISTURE COMBINED WITH STRONG SYNOPTIC
SCALE FORCING WILL SPREAD SHOWERS INTO THE WESTERN PARTS OF THE AREA
LATE WEDNESDAY NIGHT...AND WILL CONTINUE TO PUSH EAST INTO
THURSDAY. TEMPERATURES WILL WARM INTO THE LOWER AND MID 50S ON
THURSDAY FOLLOWED BY FALLING TEMPERATURES LATE IN THE DAY INTO
THURSDAY NIGHT. COLD AIR ADVECTION IN THE WAKE OF THE LOW AND FRONT
WILL BRING SOME WRAP AROUND AND LAKE INDUCED SNOW SHOWERS LATE
THURSDAY INTO THURSDAY NIGHT. RIGHT NOW...ANY SNOW ACCUMULATION
SHOULD BE MINOR. WINDY CONDITIONS ARE FORECAST DUE TO A TIGHTENING
PRESSURE GRADIENT AND MOMENTUM TRANSFER IN THE STRONG COLD AIR
ADVECTION BEHIND FRONTAL PASSAGE THURSDAY INTO THURSDAY NIGHT. WILL
CONTINUE TO MENTION THE POSSIBILITY OF 40 MPH TO 50 MPH WIND GUSTS
IN THE HWO PRODUCT.
FOR FRIDAY INTO FRIDAY NIGHT...UPR LVL TROF WILL HAVE CLOSED OFF TO
OUR NORTH AND NORTHEAST...AND WILL MOVE AWAY FROM OUR REGION. CLOUDS
AND LINGERING SNOW SHOWERS ON FRIDAY WILL TAPER OFF FROM SW TO NE
THROUGH THE DAY...FOLLOWED BY CLEARING SKIES FRIDAY NIGHT. HIGHS ON
FRIDAY WILL STRUGGLE TO WARM INTO THE LOWER AND MID 30S.
FOR THE PERIOD SATURDAY THROUGH MONDAY...MODELS CONTINUE TO DISAGREE
WHETHER UPR LVL CLOSED LOW TO OUR NE WILL ROTATE BACK TO THE
SOUTHWEST AND ALLOW COLDER AIR TO INFILTRATE FROM THE NORTH. IF THIS
OCCURS...THERE WILL BE MORE CLOUDS ACRS OUR NORTHERN ZONES WITH LAKE
EFFECT SNOW SHOWERS STAYING DOWNWIND OF THE GREAT LAKES. FOR
NOW...HAVE KEPT THE FORECAST DRY WITH SURFACE HIGH PRESSURE AT LEAST
IN PLACE AT THE SURFACE. HAVE NOT GONE AS COLD AS THE LATEST 17.12Z
ECMWF...AND HAVE RESORTED TO A BLEND OF THIS WITH HPC GUIDANCE.
&&
.AVIATION /21Z MONDAY THROUGH SATURDAY/...
COLD FRONT ALONG I-71 CORRIDOR BETWEEN CVG AND CMH THEN JOGS
SOUTHWEST THROUGH SOUTHERN INDIANA. NORTHWEST OF THE FRONT LIFR
TO IFR CIGS AND IFR TO MVFR VSBYS ARE COMMON WITH AN EAST-
NORTHEAST WIND FIELD. THE WIDESPREAD SHOWERS SOUTHEAST OF THE
FRONT WILL LIKELY NOT AFFECT ANY MORE TAFS OUTSIDE OF KILN AND
POSSIBLY KLCK IN THE NEXT FEW HOURS.
THE SURFACE LOW WILL TRACK NORTHEAST ALONG THE BOUNDARY THIS
AFTERNOON AND EVENING. MVFR CIGS AND VSBYS WILL OCCASIONALLY DROP
LOWER...MORESO OVERNIGHT. RAPID IMPROVEMENT WILL BE FOUND ONCE
NORTHWEST WINDS CAN WORK IN SOMEWHAT DRIER AND COLDER AIR AFTER
MIDNIGHT TONIGHT.
OUTLOOK...MVFR CONDITIONS ARE POSSIBLE THURSDAY. STRONG WINDS ARE
EXPECTED THURSDAY AFTERNOON AND NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...HICKMAN
AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
648 AM EST MON DEC 17 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEAST ACROSS THE REGION THIS AFTERNOON
AND EVENING. HIGH PRESSURE WILL BUILD IN TUESDAY AND WEDNESDAY. A
STRONG COLD FRONT WILL SWEEP THROUGH THE AREA ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
WEAK COLD FRONT LIES A BIT NORTHWEST OF I-71 EARLY THIS MORNING.
THIS MAY CONTINUE TO SAG A BIT FURTHER SOUTH THROUGH THE MORNING.
SHOWERS HAVE BEEN OCCURRING TO THE SOUTH OF THE FRONT THROUGH MUCH
OF THE NIGHT. SHORT RANGE GUIDANCE SUGGESTS THAT THERE COULD BE A
BREAK IN THIS ACTIVITY AROUND DAYBREAK. BUT MORE SHOWERS WILL
SPREAD IN FROM THE SOUTHWEST AS A WAVE OF LOW PRESSURE TRACKS
ALONG THE FRONT.
APPEARS THAT THIS INITIAL WAVE WILL TAKE WIDESPREAD SHOWERS ACROSS
THE SOUTHEAST HALF OF THE AREA THROUGH EARLY AFTERNOON. ONCE AGAIN
THERE COULD BE A LULL IN ACTIVITY BEFORE MAIN SURFACE LOW
APPROACHES LATER IN THE DAY.
EXPECT THIS LOW TO TRACK A BIT FURTHER NORTH THAN THE INITIAL
WAVE. THUS SHOWERS WILL OCCUR ACROSS A GREATER PART OF THE
FORECAST AREA. SHOWERS WILL CONTINUE INTO THE EVENING BEFORE
TAPERING OFF LATER TONIGHT.
INSTABILITY WILL DEVELOP INTO THE SOUTHERN PORTION OF THE FORECAST
AREA THIS AFTERNOON AND EVENING. THUS SOME THUNDERSTORMS ARE
POSSIBLE. FORECAST SOUNDINGS FROM THE 00Z/06Z NAM DO NOT LOOK TOO
IMPRESSIVE. BUT LATEST RAP RUNS MANAGE A BIT MORE INSTABILITY.
CANNOT RULE OUT A FEW STRONGER STORMS MAINLY TO THE SOUTH OF
CINCINNATI LATE THIS AFTERNOON AND EARLY THIS EVENING.
CONCERNED THAT CLOUDS AND OCCASIONAL PRECIPITATION WILL LIMIT
TEMPERATURES. SO HAVE MOSTLY SHADED ON THE COOL SIDE OF GUIDANCE
FOR HIGHS. MOS LOOKED IN THE BALL PARK FOR LOWS.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
COULD BE A FEW LINGERING SHOWERS IN THE FAR EASTERN COUNTIES TO
START TUESDAY. BUT THE MAIN TREND WILL BE FOR HIGH PRESSURE TO
BUILD IN DURING THE PERIOD. A WEAK LOW WILL PASS ACROSS THE GREAT
LAKES TUESDAY NIGHT WHICH WILL TEMPORARILY SUPPRESS THE HIGH
SOMEWHAT. BUT THIS SHOULD ONLY BRING SOME CLOUDS TO THE NORTHERN
COUNTIES.
STAYED SLIGHTLY BELOW MOS FOR TUESDAY HIGHS. OTHERWISE A MOS BLEND
LOOKED REASONABLE FOR TEMPERATURES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A VIGOROUS SHORT WAVE WILL PIVOT NORTHEAST THROUGH THE REGION
DURING THE EARLY PART OF THE PERIOD. THIS WILL TAKE A DEEPENING
SURFACE LOW TO THE NORTHWEST OF THE FORECAST AREA. BUT A TRAILING
STRONG COLD FRONT WILL CROSS THE AREA ON THURSDAY. THERE ARE STILL
SOME SLIGHT TIMING DISCREPANCIES WITH THIS. HAVE GONE TOWARDS THE
SLIGHTLY SLOWER 00Z ECMWF WHICH HAS SUPPORT FROM THE 00Z CANADIAN.
SHOWERS WILL BE WIDESPREAD AHEAD OF THIS SYSTEM. THEY WILL SPREAD
INTO THE WESTERN COUNTIES LATE WEDNESDAY NIGHT AND MOVE ACROSS THE
ENTIRE AREA ON THURSDAY. TEMPERATURES WILL BE NON-DIURNAL. DO
EXPECT SOME DROP OFF IN READINGS WEDNESDAY EVENING BEFORE STARTING
TO RISE LATER IN THE NIGHT. TEMPERATURES WILL SHARPLY DROP AFTER
THE FRONTAL PASSAGE THURSDAY AFTERNOON. MODELS STILL NOT
DEVELOPING MUCH INSTABILITY WITH THIS. BUT WILL HAVE TO WATCH FOR
THUNDER POTENTIAL GIVEN STRONG DYNAMICS.
EXPECT WRAP AROUND SNOW SHOWERS WITH A BRIEF WINDOW FORM SOME LAKE
ENHANCEMENT THURSDAY NIGHT INTO FRIDAY. IN ADDITION...COLD
ADVECTION AND A STRONG PRESSURE GRADIENT WILL RESULT IN BLUSTERY
WINDS FROM AFTER FRONTAL PASSAGE RIGHT INTO FRIDAY. AS THE ENTIRE
SYSTEM LIFTS FURTHER AWAY FROM THE REGION THE WINDS WILL SUBSIDE
AND THE CHANCE OF SNOW SHOWERS WILL DIMINISH.
COLD HIGH PRESSURE CENTERED OVER THE UPPER MIDWEST WILL RIDGE
SOUTHEAST INTO THE REGION FOR THE WEEKEND. TEMPERATURES WILL BE AT
OR BELOW NORMAL FROM THURSDAY NIGHT THROUGH SUNDAY.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
A FRONTAL BOUNDARY CONTINUES TO BE POSITIONED FROM AROUND KCVG TO
KCMH. AN AREA OF LOW PRESSURE WILL MOVE NORTHEAST AND ACROSS THE
AREA TODAY AND ENHANCE RAIN SHOWER ACTIVITY. THIS AREA OF LOW
PRESSURE WILL BEGIN TO MOVE NE OF THE AREA TONIGHT AND RAIN WILL
COME TO AN END ACROSS THE FA.
CIGS ARE GENERALLY PRETTY LOW NW OF THE BOUNDARY WITH KDAY
EXPERIENCING LIFR CONDITIONS. SE OF THIS BOUNDARY MANY LOCATIONS
HAVE MVFR TO VFR CIGS AND VSBYS. WITH THIS BOUNDARY NEAR MANY OF
THE TAF SITES ANY SLIGHT MOVEMENT IN THE BOUNDARY COULD CAUSE A
CHANGE IN WIND SHIFT AND IN CIGS. TIMED OUT THE MOVEMENT OF THE
BOUNDARY IN THE TAFS AND THE SUBSEQUENT CHANGES IN THE CIG
FORECASTS.
KEPT THUNDER MENTION OUT OF THE TAFS FOR NOW AS THE BEST
INSTABILITY WILL REMAIN SOUTH OF THE TAF SITES.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES WILL BE POSSIBLE ON
TUESDAY. MVFR CONDITIONS ARE AGAIN EXPECTED ON THURSDAY. STRONG
WINDS ARE LIKELY THURSDAY AFTERNOON AND NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
448 AM EST MON DEC 17 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEAST ACROSS THE REGION THIS AFTERNOON
AND EVENING. HIGH PRESSURE WILL BUILD IN TUESDAY AND WEDNESDAY. A
STRONG COLD FRONT WILL SWEEP THROUGH THE AREA ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
WEAK COLD FRONT LIES A BIT NORTHWEST OF I-71 EARLY THIS MORNING.
THIS MAY CONTINUE TO SAG A BIT FURTHER SOUTH THROUGH THE MORNING.
SHOWERS HAVE BEEN OCCURRING TO THE SOUTH OF THE FRONT THROUGH MUCH
OF THE NIGHT. SHORT RANGE GUIDANCE SUGGESTS THAT THERE COULD BE A
BREAK IN THIS ACTIVITY AROUND DAYBREAK. BUT MORE SHOWERS WILL
SPREAD IN FROM THE SOUTHWEST AS A WAVE OF LOW PRESSURE TRACKS
ALONG THE FRONT.
APPEARS THAT THIS INITIAL WAVE WILL TAKE WIDESPREAD SHOWERS ACROSS
THE SOUTHEAST HALF OF THE AREA THROUGH EARLY AFTERNOON. ONCE AGAIN
THERE COULD BE A LULL IN ACTIVITY BEFORE MAIN SURFACE LOW
APPROACHES LATER IN THE DAY.
EXPECT THIS LOW TO TRACK A BIT FURTHER NORTH THAN THE INITIAL
WAVE. THUS SHOWERS WILL OCCUR ACROSS A GREATER PART OF THE
FORECAST AREA. SHOWERS WILL CONTINUE INTO THE EVENING BEFORE
TAPERING OFF LATER TONIGHT.
INSTABILITY WILL DEVELOP INTO THE SOUTHERN PORTION OF THE FORECAST
AREA THIS AFTERNOON AND EVENING. THUS SOME THUNDERSTORMS ARE
POSSIBLE. FORECAST SOUNDINGS FROM THE 00Z/06Z NAM DO NOT LOOK TOO
IMPRESSIVE. BUT LATEST RAP RUNS MANAGE A BIT MORE INSTABILITY.
CANNOT RULE OUT A FEW STRONGER STORMS MAINLY TO THE SOUTH OF
CINCINNATI LATE THIS AFTERNOON AND EARLY THIS EVENING.
CONCERNED THAT CLOUDS AND OCCASIONAL PRECIPITATION WILL LIMIT
TEMPERATURES. SO HAVE MOSTLY SHADED ON THE COOL SIDE OF GUIDANCE
FOR HIGHS. MOS LOOKED IN THE BALL PARK FOR LOWS.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
COULD BE A FEW LINGERING SHOWERS IN THE FAR EASTERN COUNTIES TO
START TUESDAY. BUT THE MAIN TREND WILL BE FOR HIGH PRESSURE TO
BUILD IN DURING THE PERIOD. A WEAK LOW WILL PASS ACROSS THE GREAT
LAKES TUESDAY NIGHT WHICH WILL TEMPORARILY SUPPRESS THE HIGH
SOMEWHAT. BUT THIS SHOULD ONLY BRING SOME CLOUDS TO THE NORTHERN
COUNTIES.
STAYED SLIGHTLY BELOW MOS FOR TUESDAY HIGHS. OTHERWISE A MOS BLEND
LOOKED REASONABLE FOR TEMPERATURES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A VIGOROUS SHORT WAVE WILL PIVOT NORTHEAST THROUGH THE REGION
DURING THE EARLY PART OF THE PERIOD. THIS WILL TAKE A DEEPENING
SURFACE LOW TO THE NORTHWEST OF THE FORECAST AREA. BUT A TRAILING
STRONG COLD FRONT WILL CROSS THE AREA ON THURSDAY. THERE ARE STILL
SOME SLIGHT TIMING DISCREPANCIES WITH THIS. HAVE GONE TOWARDS THE
SLIGHTLY SLOWER 00Z ECMWF WHICH HAS SUPPORT FROM THE 00Z CANADIAN.
SHOWERS WILL BE WIDESPREAD AHEAD OF THIS SYSTEM. THEY WILL SPREAD
INTO THE WESTERN COUNTIES LATE WEDNESDAY NIGHT AND MOVE ACROSS THE
ENTIRE AREA ON THURSDAY. TEMPERATURES WILL BE NON-DIURNAL. DO
EXPECT SOME DROP OFF IN READINGS WEDNESDAY EVENING BEFORE STARTING
TO RISE LATER IN THE NIGHT. TEMPERATURES WILL SHARPLY DROP AFTER
THE FRONTAL PASSAGE THURSDAY AFTERNOON. MODELS STILL NOT
DEVELOPING MUCH INSTABILITY WITH THIS. BUT WILL HAVE TO WATCH FOR
THUNDER POTENTIAL GIVEN STRONG DYNAMICS.
EXPECT WRAP AROUND SNOW SHOWERS WITH A BRIEF WINDOW FORM SOME LAKE
ENHANCEMENT THURSDAY NIGHT INTO FRIDAY. IN ADDITION...COLD
ADVECTION AND A STRONG PRESSURE GRADIENT WILL RESULT IN BLUSTERY
WINDS FROM AFTER FRONTAL PASSAGE RIGHT INTO FRIDAY. AS THE ENTIRE
SYSTEM LIFTS FURTHER AWAY FROM THE REGION THE WINDS WILL SUBSIDE
AND THE CHANCE OF SNOW SHOWERS WILL DIMINISH.
COLD HIGH PRESSURE CENTERED OVER THE UPPER MIDWEST WILL RIDGE
SOUTHEAST INTO THE REGION FOR THE WEEKEND. TEMPERATURES WILL BE AT
OR BELOW NORMAL FROM THURSDAY NIGHT THROUGH SUNDAY.
&&
.AVIATION /09Z MONDAY THROUGH FRIDAY/...
A FRONTAL BOUNDARY IS CURRENTLY LOCATED NEAR A LINE FROM KCVG TO
KLCK. AN AREA OF LOW PRESSURE WILL APPROACH THE AREA ON MONDAY
ENHANCING SHOWER ACTIVITY ALONG AND TO THE SE OF THIS BOUNDARY.
THIS AREA OF LOW PRESSURE WILL MOVE OUT OF THE AREA MONDAY NIGHT
AND DRY CONDITIONS WILL BEGIN TO RETURN TO THE TAF SITES BY THE
END OF THE TAF PERIOD. THE BEST INSTABILITY STAYS SOUTH OF THE TAF
SITES AND THEREFORE LEFT THUNDER OUT OF THE TAFS AT THIS TIME.
MVFR CIGS AND VSBYS WILL GRADUALLY DEVELOP ACROSS THE TAF SITES BY
MORNING AND REMAIN ACROSS THE AREA FOR MONDAY. SOME LOCATIONS MAY
ALSO BRIEFLY SEE IFR OR LIFR VSBYS OVERNIGHT AND INTO THE EARLY
MORNING DAYTIME HOURS.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES WILL BE POSSIBLE FROM
MONDAY NIGHT THROUGH TUESDAY. MVFR CONDITIONS ARE AGAIN EXPECTED ON
THURSDAY. STRONG WINDS ARE LIKELY THURSDAY AFTERNOON AND NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
118 AM EST MON DEC 17 2012
.SYNOPSIS...
A WEAK COLD FRONTAL BOUNDARY LOCATED SOUTHEAST OF THE I-71
CORRIDOR WILL SEE LOW PRESSURE MOVE TO THE NORTHEAST ALONG IT ON
MONDAY. THIS WILL COMBINE WITH AN EASTWARD MOVING UPPER LEVEL
TROUGH TO INITIATE SHOWERS AND POSSIBLY SOME THUNDERSTORMS. HIGH
PRESSURE WILL BUILD SOUTH OF THE OHIO VALLEY THROUGH THE MIDDLE OF
THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
17.00Z KILN SOUNDING CAME IN WITH MINUSCULE INSTBY...WITH < 100
J/KG MUCAPE BUT A SOMEWHAT DECENT MID-LEVEL LAPSE RATE IN EXCESS
OF 7 C/KM. MID EVENING WATER VAPOR IMAGERY CONTINUES TO DEPICT A
SHORTWAVE MOVING THROUGH IL TOWARD OH BUT SEEMS TO BE SHEARING
OUT/DEAMPLIFYING A BIT. LAST FEW SETS OF RAP DATA HAVE REALLY
BACKED OFF ON DEGREE OF FORCING WITH THIS WAVE AND HAVE DECREASED
LOW LEVEL JET FOCUS INTO THE WEAK FRONTAL BOUNDARY SAGGING
THROUGH WRN OH. THE RESULT OVER THE LAST FEW HOURS...IS A
SMALLER/LIGHTER QPF FIELD IN THE RAP OVER VERSIONS LOOKED AT
THROUGH THE AFTERNOON. EXPERIMENTAL HRRR HAS SEEN SOME
OUTAGES...BUT LAST AVAILABLE RUN /22Z/ STILL SHOWED A RATHER
HEALTHY BATCH OF SHOWERS DEVELOPING TO THE SW OF CVG AND MOVING
ACROSS OUR SRN/SERN AREAS. THE NEW 17.21 SREF PROBS FOR MEASURABLE
PRECIPITATION HAVE DECREASED MARKEDLY AS WELL FROM 17.15Z VALUES.
ALL IN ALL...WILL MAINTAIN CURRENT AXIS OF RAIN CHANCES BEGINNING
IN NEXT COUPLE OF HOURS ACROSS FAR SRN FORECAST AREA...AND PEAKING
IN THE HOURS AFTER MIDNIGHT FROM SOUTH OF CVG EAST/NORTHEAST INTO
SCNTL OH. BUT HAVE DECREASED CHANCES A BIT FROM PREVIOUS
UPDATE. STILL HAVE A LITTLE THUNDER IN THE GRIDS...BUT BASED ON
THE KILN SOUNDING LIGHTNING IS GOING TO BE TOUGH TO COME BY WITH
EQUILIBRIUM LEVEL TEMPS BARELY TO -20C AND SUCH MEAGER INSTBY.
WITH CLEARING OF HIGH CLOUDS IN THE WEST FOR A FEW HOURS THIS
EVENING...THIS ALLOWED A LOCAL TEMP DROP MORE THAN I HAD PREVIOUS
ANTICIPATED AND THUS HAVE DROPPED MIN TEMPS IN THE WESTERN 1/3RD
OF THE FORECAST AREA. A LITTLE FOG COULD FORM IN THIS AREA BUT IT
APPEARS PER SATELLITE IMAGERY THAT LOW CLOUDS ARE QUICKLY
REDEVELOPING IN THE MOIST ADVECTION SPOKE OF PREVIOUSLY. IT
WOULDN/T TAKE LONG FOR DENSE FOG TO FORM IN THIS NARROW CLEAR SLOT
BETWEEN THE LOW CLOUDS LAGGING THE WEAK COLD FRONT...AND THE THICK
CIRRUS MOVING EAST THROUGH THE AREA. WILL MONITOR.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
WEAK SURFACE FORCING WITH THE NEWD MOVING LOW WILL COMBINE WITH
THE UPWARD MOTION AND VORTICITY MAXIMA AHEAD OF THE UPPER LEVEL
TROUGH TO SPARK ACTIVITY LATE TONIGHT AND MORESO TOMORROW.
UNFORTUNATELY THE SHOWERS SHOULD INITIATE ALONG THE MOISTURE
CONVERGENCE AXIS WHICH IS HARD TO PLACE. BEST ESTIMATES RUN ALONG
THE OHIO RIVER SOUTHWEST OF CINCINNATI...THEN JOG NORTHEAST TO
COLUMBUS. THE LOW LEVEL FORCING WITH THE SURFACE TROUGH IS WELL
AHEAD OF THE STRONGER UPPER LEVEL FORCING WITH THE MID LEVEL
SHORTWAVE...WHICH WILL GIVE A PROLONGED POTENTIAL FOR SHOWER
ACTIVITY BUT NOT A CLEAR CUT INDICATION OF THE
HEAVIEST/STRONGEST/MOST LIKELY PLACEMENT OF THE RAIN. BY DAYBREAK
TUESDAY...THE SURFACE LOW IS WELL EAST OF THE REGION AND THE UPPER
LOW IS EXITING OHIO. ANY RAIN WILL HAVE ENDED OVERNIGHT MONDAY.
TEMPERATURES REMAIN UNSEASONABLY WARM BUT ALL OF THE GUIDANCE WERE
PEGGED WITHIN A FEW DEGREES OF EACH OTHER AND NO SIGNIFICANT
CHANGES WERE MADE HERE. CLOUD COVER WILL BE ON THE DECREASE
TUESDAY BUT ASIDE FROM THIS...IT SHOULD BE A RELATIVELY CLOUDY AND
MILD PERIOD...PARTICULARLY FOR MID DECEMBER.
SPC HAS THUNDERSTORMS OVER THE REGION WITH A SLIGHT CHANCE OF
SEVERE NOTED FOR MUCH OF KENTUCKY. WITH THE DISJOINTED NATURE OF
THE SURFACE AND UPPER FORCING...NO CLEAR CUT STRONG VORT
MAXIMA...AND SIGNIFICANT CLOUD COVER EXPECTED...I DID NOT FEEL THE
NECESSARY INGREDIENTS FOR PARTICULARLY STRONG STORMS WERE PRESENT.
THE THUNDER FORECAST I USED TOOK 12Z NAM CAPES OVER 200 AND ADDED
THEM WHERE RAIN CHANCE WAS GREATER THAN 30...YIELDING A NARROW
SWATH SOUTHEAST OF THE I-71 CORRIDOR LATER TONIGHT AND THEN
GENERALLY OVERSPREADING KY EARLY TOMORROW.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
OPERATIONAL MODELS WERE COMING INTO A BETTER AGREEMENT FOR THE NEXT
WEATHER MAKER TO AFFECT THE AREA THURSDAY INTO FRIDAY. HAVE USED A
BLEND OF THE OPERATIONAL 16.12Z GFS AND THE 16.00Z ECMWF.
THE LONG TERM WILL START OUT QUIET ON WEDNESDAY AS MID LEVEL RIDGING
WILL BE IN PLACE ACROSS THE OHIO VALLEY OUT AHEAD OF AFOREMENTIONED
WEATHER SYSTEM DEVELOPING ACROSS THE SRN PLAINS. CLOUDS WILL
INCREASE THROUGH THE DAY...BUT WE SHOULD AT LEAST SEE PARTLY TO
MOSTLY SUNNY SKIES EARLY ON. HIGH TEMPERATURES WILL CONTINUE TO BE
ABOVE NORMAL...RANGING FROM THE LOWER 50S NORTH TO THE UPPER 50S
SOUTH.
FOR THE PERIOD WEDNESDAY NIGHT INTO THURSDAY NIGHT...A DEEPENING MID
LEVEL TROF AND DEEPENING SFC LOW PRESSURE SYSTEM WILL PULL NORTHEAST
FROM THE SRN PLAINS TO THE GREAT LAKES/OHIO VALLEY REGION. THE TRACK
OF THE SFC LOW CONTINUES TO BE NW OF THE REGION...SO ANY MAJOR
WINTER WEATHER WILL STAY WELL TO OUR NW. THE LOW WILL BE ASSOCIATED
WITH A STRONG COLD FRONT. DEEP MOISTURE COMBINED WITH STRONG
SYNOPTIC SCALE FORCING WILL SPREAD SHOWERS INTO THE REGION WEDNESDAY
NIGHT AND WILL CONTINUE INTO THURSDAY. PCPN SHOULD TAPER OFF SOME
BEHIND FRONTAL PASSAGE. TEMPERATURES WILL WARM INTO THE LOWER AND MID
50S ON THURSDAY FOLLOWED BY FALLING TEMPERATURES LATE IN THE DAY
INTO THURSDAY NIGHT. COLD AIR ADVECTION IN THE WAKE OF THE LOW AND
FRONT WILL BRING SOME WRAP AROUND AND LAKE INDUCED SNOW SHOWERS LATE
THURSDAY INTO THURSDAY NIGHT. RIGHT NOW...ANY SNOW ACCUMULATION
SHOULD BE MINOR. WINDY CONDITIONS ARE FORECAST DUE TO A TIGHTENING
PRESSURE GRADIENT AND MOMENTUM TRANSFER IN THE STRONG COLD AIR
ADVECTION BEHIND FRONTAL PASSAGE THURSDAY INTO THURSDAY NIGHT. SO
WILL MENTION THIS POTENTIAL HAZARD IN THE HWO PRODUCT.
FOR FRIDAY INTO FRIDAY NIGHT...UPR LVL TROF WILL HAVE CLOSED OFF TO
OUR NORTH AND NORTHEAST...AND WILL QUICKLY MOVE AWAY FROM OUR
REGION. CLOUDS AND LINGERING SNOW SHOWERS ON FRIDAY WILL TAPER OFF
FROM SW TO NE THROUGH THE DAY...FOLLOWED BY CLEARING SKIES FRIDAY
NIGHT. THE COLDEST TEMPERATURES OF THE WEEK APPEAR TO BE ON FRIDAY
WITH HIGHS STRUGGLING TO WARM INTO THE LOWER AND MID 30S.
FOR SATURDAY INTO SUNDAY...UPR LVL CLOSED LOW IS EXPECTED TO ROTATE
NORTHEASTWARD WHILE OUR REGION STAYS IN A NORTHWEST FLOW ALOFT ALONG
WITH HIGH PRESSURE AT THE SURFACE. DRY WEATHER ALONG WITH NEAR
SEASONAL TEMPERATURES WILL BE FORECAST ATTM.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
A FRONTAL BOUNDARY IS CURRENTLY LOCATED NEAR A LINE FROM KCVG TO
KLCK. AN AREA OF LOW PRESSURE WILL APPROACH THE AREA ON MONDAY
ENHANCING SHOWER ACTIVITY ALONG AND TO THE SE OF THIS BOUNDARY.
THIS AREA OF LOW PRESSURE WILL MOVE OUT OF THE AREA MONDAY NIGHT
AND DRY CONDITIONS WILL BEGIN TO RETURN TO THE TAF SITES BY THE
END OF THE TAF PERIOD. THE BEST INSTABILITY STAYS SOUTH OF THE TAF
SITES AND THEREFORE LEFT THUNDER OUT OF THE TAFS AT THIS TIME.
MVFR CIGS AND VSBYS WILL GRADUALLY DEVELOP ACROSS THE TAF SITES BY
MORNING AND REMAIN ACROSS THE AREA FOR MONDAY. SOME LOCATIONS MAY
ALSO BRIEFLY SEE IFR OR LIFR VSBYS OVERNIGHT AND INTO THE EARLY
MORNING DAYTIME HOURS.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES WILL BE POSSIBLE FROM
MONDAY NIGHT THROUGH TUESDAY. MVFR CONDITIONS ARE AGAIN EXPECTED ON
THURSDAY. STRONG WINDS ARE LIKELY THURSDAY AFTERNOON AND NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...BINAU
SHORT TERM...FRANKS
LONG TERM...HICKMAN
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
250 PM EST MON DEC 17 2012
.SHORT TERM (TONIGHT AND TUESDAY)...SKIES REMAIN CLOUDY TO MOSTLY
CLOUDY THIS AFTERNOON WITH GENERALLY LIGHT RAIN SHOWERS MOVING NE
ACROSS THE FORECAST AREA ASSOCIATED WITH A WEAK SHORTWAVE ABOUT TO
EXIT THE REGION INTO THE CENTRAL APPALACHIANS. STRONG TO SEVERE
THUNDERSTORMS PRODUCING LARGE HAIL AND HIGH WINDS HAVE DEVELOPED
WITH SCATTERED ACTIVITY MOVING INTO WESTERN KY AND TN JUST WEST OF
BNA. AIR MASS TO THE WEST OF THE PLATEAU BECOMING UNSTABLE AS SKIES
HAVE CLEARED AHEAD OF STRONGER SHORTWAVE MOVING INTO THE MS AND
LOWER OH VALLEYS.
THESE STORMS LIKELY TO CONTINUE NEXT SEVERAL HOURS BEFORE WEAKENING
AS THEY MOVE INTO MORE STABLE AIRMASS IN EAST TN. NAM AND RUC MODELS
FORECAST THIS AREA TO MOVE MOSTLY NE INTO SE KY LATER THIS AFTERNOON
AND EVENING. TEMPERATURES OVER FORECAST AREA ARE NOW IN THE LOWER
50S NE AND HIGHER ELEVATIONS TO MID 50S TO NEAR 60 EXCEPT LOWER 60S
AT CHA. A FEW STRONG TO SEVERE STORMS ARE POSSIBLE EITHER LATE THIS
AFTERNOON OR EARLY EVENING MAINLY PLATEAU AND CENTRAL VALLEY WITH
HAIL TO ONE INCH AND DAMAGING WIND GUSTS. COLD FRONT ALONG MS RIVER
WILL SWING THROUGH THE EASTERN TENNESSEE VALLEY AND MOUNTAINS BY
LATE TONIGHT ENDING PRECIPITATION IN THE SOUTH THIS EVENING. A
SECONDARY FRONT AND SHORTWAVE EARLY TUESDAY WILL ALLOW SHOWERS TO
LINGER ACROSS SW VA AND EXTREME NE TN INTO EARLY TUESDAY MORNING.
SKIES WILL BEGIN TO CLEAR LATE TONIGHT FROM THE SW AND BY TUESDAY
AFTERNOON CLOUDS SHOULD START TO BREAK UP OVER NE SECTIONS. NAM/GFS
GUIDANCE SIMILAR TONIGHT SO FOLLOWED CLOSE AND FOR TUESDAY AS WELL.
HIGHS TUESDAY WILL STILL BE ABOUT 5 DEGREES ABOVE NORMAL ALL AREAS.
.LONG TERM (TUESDAY NIGHT THROUGH MONDAY)...MODELS ARE IN GOOD
AGREEMENT THROUGH THE EXTENDED PERIOD...AND GENERALLY REVEAL ONE
MAIN SYSTEM AFFECTING THE FORECAST AREA ON THURSDAY. HIGH PRESSURE
OVER THE EASTERN HALF OF THE NATION WILL BRING DRY AND TRANQUIL
CONDITIONS OVER THE FORECAST AREA FOR TUESDAY NIGHT AND WEDNESDAY. A
LOW PRESSURE SYSTEM IS THEN PROGGED TO DEVELOP OVER THE SOUTHERN
PLAINS ON WEDNESDAY...WHICH WILL THEN MOVE NORTHEASTWARD ACROSS THE
LOWER OHIO RIVER VALLEY WEDNESDAY NIGHT. A STRONG 850 MB LOW-LEVEL
JET (IN EXCESS OF 50 KT) IS PROGGED TO DEVELOP OVER THE TN RIVER
VALLEY AHEAD OF ITS TRAILING COLD FRONT. MODEL SOUNDINGS AROUND THE
MOUNTAINS INDICATE A VEERING WIND PROFILE...SOUTH TO SOUTHEASTERLY
LOW-LEVEL WINDS PERPENDICULAR TO THE MOUNTAINS...AND A DEEP STABLE
LAYER EXTENDING ABOVE THE MOUNTAIN RIDGES. THUS...IT APPEARS THAT
DAMAGING WINDS DUE TO MOUNTAIN WAVES WILL BE A GOOD POSSIBILITY LATE
WEDNESDAY NIGHT INTO THURSDAY MORNING ALONG THE FOOTHILLS OF THE
MOUNTAINS. FOR NOW...WILL PLAN TO MENTION THIS POSSIBILITY IN THE
HAZARDOUS WEATHER OUTLOOK...BUT HIGH WIND WATCHES AND/OR WARNINGS
MAY BE NEEDED FOR THE FOOTHILLS IN LATER FORECASTS. MODELS AGREE
THAT MOISTURE WILL DECREASE RAPIDLY BEHIND THE COLD FRONT THURSDAY
NIGHT...SO THAT THE CHANGE OVER TO SNOW SHOWERS BEHIND THE FRONT
SHOULD BE QUICK AND MOSTLY LIMITED TO THE HIGHER ELEVATIONS. ANOTHER
WEAK COLD FRONT IS THEN PROGGED TO MOVE THROUGH THE FORECAST AREA
SATURDAY NIGHT OR SUNDAY...BUT THE MODELS INDICATE THAT LIMITED
MOISTURE ASSOCIATED WITH IT SHOULD RESULT MAINLY IN JUST AN INCREASE
IN CLOUDS. AS FOR TEMPS...WILL TREND TOWARD THE GFS GUIDANCE NUMBERS
THROUGH THE EXTENDED PERIOD...WHICH ARE IN GOOD AGREEMENT WITH THE
ENSEMBLE MEANS.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 41 57 35 66 45 / 30 0 0 0 40
KNOXVILLE AIRPORT, TN 42 55 34 64 44 / 40 0 0 0 30
OAK RIDGE, TN 41 54 35 63 45 / 40 0 0 0 30
TRI CITIES AIRPORT, TN 39 51 30 60 38 / 50 10 0 0 20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TD/DMG
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1115 PM CST SUN DEC 16 2012
.UPDATE...FOR 06Z AVIATION FORECAST
&&
.AVIATION...
BEGINNING TO SEE A LITTLE BIT OF LIGHT RAIN BREAKING OUT AROUND
MEMPHIS AT 0415Z AS SREF NOW SHOWING UPPER TROUGH THAT IS BACK
OVER SOUTHERN PLAINS BEGINNING TO MOVE THIS WAY. LATEST RUC RUN
DEVELOPS THIS ACTIVITY OVER WESTERN TENNESSEE...NORTHERN
MISSISSIPPI AND FAR WESTERN KENTUCKY THROUGH ABOUT 07Z THEN WORKS
IT NORTHEASTWARD AND INTO WESTERN MIDDLE TENNESSEE AFTER 07Z AND
INTO THE NASHVILLE AREA AROUND 09Z AND CONTINUE TO OVERSPREAD
MIDDLE TENNESSEE DURING THE LATE NIGHT. THIS ACTIVITY IS ALIGNED
PRETTY MUCH WITH THE 70 KNOT MID-LEVEL JET THAT RUNS SOUTHWEST TO
NORTHEAST AND OUT AHEAD OF A NOW STATIONARY FRONTAL BOUNDARY
DRAPED ALONG THE OHIO RIVER DOWN THROUGH POPLAR BLUFF MISSOURI TO
ABOUT TEXARKANA AT 04Z. FRONTAL BOUNDARY NOT PROGGED TO MOVE MUCH
IN THE OVERNIGHT. SELS HAS MID STATE OUTLOOKED FOR THUNDERSTORMS
ON MONDAY WITH GOOD PART OF THE MID STATE UNDER A SLIGHT RISK FOR
SEVERE. A GOOD SHOT OF POSITIVE VORTICITY WILL MOVE INTO THE MID
STATE FROM THE SOUTHWEST AROUND 14Z THROUGH 20Z ON MONDAY. BEST
CHANCE FOR THE STRONGER STORMS WOULD BE LATE MORNING THROUGH THE
AFTERNOON. BELIEVE BEST CHANCE FOR SEVERE WOULD BE EASTERN
AREAS/PLATEAU.
BOYD
&&
.PREV DISCUSSION... /ISSUED 852 PM CST SUN DEC 16 2012/
UPDATE...
LATEST RADAR IMAGERY INDICATES RAIN HAS EXITED THE FORECAST AREA
THIS EVENING...WHILE SATELLITE IMAGERY SHOWS MID/UPPER LEVEL
CLOUDS RAPIDLY SHIFTING EASTWARD AS SHORTWAVE EXITS THE REGION.
HOWEVER...LOW CLOUDS CAN BE SEEN RAPIDLY FORMING OVER WEST
TN...AND ALL MODEL GUIDANCE INDICATES REDEVELOPMENT OF SHOWERS
OVERNIGHT FROM WEST TN INTO WESTERN PARTS OF THE MID STATE. HAVE
ADJUSTED POPS TO SHOW ONLY SLIGHT CHANCE THROUGH MIDNIGHT...BUT
INCREASE TO CHANCE/LIKELY AFTERWARDS AS THE NEXT SHORTWAVE
APPROACHES AND SPAWNS NEW ACTIVITY TOWARDS SUNRISE. TWEAKED LOW
TEMPS AND SKY COVER FOR TONIGHT BASED ON LATEST TRENDS...BUT REST
OF FORECAST GENERALLY ON TRACK.
PREV DISCUSSION... /ISSUED 604 PM CST SUN DEC 16 2012/
UPDATE...FOR 00Z AVIATION FORECAST
AVIATION...
GOOD SURFACE PRESSURE GRADIENT ACROSS MIDDLE TENNESSEE WITH STRONG
PRESSURE FALLS NOW OCCURRING OVER THE WEST HALF WITH GUSTS TO 37
MPH AT BNA MOMENTS AGO. LOOK FOR WIND GUSTS ON THE ORDER OF 30 TO
35 KNOTS TO CONTINUE FOR THE NEXT HOUR OR TWO AS BACK EDGE OF RAIN
SHIELD PULLS EAST AND 80+ KNOT MID LEVEL JET PUNCHES UP THROUGH
MIDDLE TENNESSEE. LOOKS LIKE SHORT WAVE WILL WORK EASTWARD AND
EXIT MID STATE BY AROUND 03Z. I EXPECT IT WILL TAKE THE RAIN AREA
WITH IT AS IT MOVES INTO EASTERN TENNESSEE BY 03Z THIS EVENING.
ANOTHER SHORT WAVE MORE IN LINE WITH BROADER UPPER TROUGH ENERGY TO
OUR WEST WILL HEAD THIS WAY AFTER 06Z TONIGHT SO WILL HAVE AT
LEAST A MENTION OF SCATTERED SHOWERS IN THE OVERNIGHT BUT TIMING
UNCERTAIN AND CONFIDENCE LOW.
MUCAPES CLIMB > 500 J/KG DURING THE DAY MONDAY ACROSS MIDDLE
TENNESSEE SO AM EXPECTING SCATTERED THUNDERSTORMS FROM ABOUT 15Z
TO 22Z. BEST TIMING FOR FROPA BASED ON WIND SHIFT LINE WILL BE
LATE AFTERNOON AT CKV...EARLY EVENING AT BNA AND TOWARDS MIDNIGHT
MONDAY NIGHT AT CSV.
BOYD
PREV DISCUSSION... /ISSUED 310 PM CST SUN DEC 16 2012/
DISCUSSION...SFC FRONT IS STILL LOCATED WELL TO THE NW OVER THE
MID MS VALLEY BETWEEN PADUCAH AND ST LOUIS. HOWEVER...THERE IS A
SFC TEMPERATURE DISCONTINUITY OVER THE DEEP SOUTH...OVER SERN
LA...SERN MS...CNTRL AL AND CNTRL GA. ALOFT...A LARGE UPPER TROUGH
IS LOCATED OVER THE LEE OF THE ROCKIES WITH STRONG SWLY FLOW OVER
THE MS/OH VALLEYS. ONE THING...LOOKING AT LIGHTNING DATA...NUMBER
OF LIGHTNING STRIKES HAS DECLINED SIGNIFICANTLY OVER THE DEEP SOUTH
WITH FEWER THAN 5 STRIKES IN RECENT IMAGES.
UPPER TROUGH SLOWLY TRANSLATES EWD GENERATING A SFC LOW ON THE END
OF THE FRONT OVER TX WHICH PUSHES NEWD ACROSS THE MID SOUTH ON MON.
AFTER THE LOW PASSES...BRIEF WLY FLOW FROM A HIGH PRESSURE RIDGE
OVER THE GULF COAST COVERS THE AREA. LOW LEVEL FLOW QUICKLY COMES
BACK TO SLY ON TUE NGT AS A MAJOR UPPER TROUGH PLOWS THROUGH THE
PLAINS ON WED NGT. THE ASSOCD STRONG SFC LOW AND FRONT CROSSES THE
OH/TN VALLEYS ON THU BRINGING ADDITIONAL RAINFALL FOR WED NGT AND
THU.
THE FRONT PASSES ON TO THE EAST WITH A DECENT SHOT OF COLD AIR
OVER THE STATE FROM THU PM THROUGH FRI DROPPING AFTERNOON LOWS
INTO INTO THE 45-50 RANGE AND NIGHTIME LOWS INTO THE 25-30 RANGE.
GOOD WEATHER FOR THE WEEKEND WITH TEMPS A LITTLE ABOVE NORMAL.
SPC HAS OUTLOOKED SLIGHT RISK SEVERE FOR MUCH OF THE ERN HALF OF
THE MIDSTATE. PROGS SHOW INSTABILITY INCREASING SIGNIFICANTLY BY
MIDDAY WITH SIGNIFICANT 0-3 KM SHEAR.
HPC IS PREDICTING 0.1 TO 0.5 INCHES OF ADDITIONAL RAINFALL WITH
THE CURRENT SYSTEM AND ANOTHER .25 TO .75 INCHES FOR THE SYSTEM ON
WED NGT/THU.
FINALLY...THE CPC FOLKS SHOW NEAR NORMAL TEMPS FOR THE 6-14 DAY
PERIOD BUT ABOVE NORMAL RAINFALL.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
304 PM CST MON DEC 17 2012
.TONIGHT AND TUESDAY...FORECAST CONFIDENCE...MEDIUM
STUBBORN LOW CLOUD DECK CONTINUES ACROSS SOUTHERN WISCONSIN. BULK OF
MODELS CONTINUE TO SUGGEST IT WILL SCATTER OUT LATE AFTERNOON AND
EVENING...BUT MODELS ORIGINALLY HAD THE SUN POKING OUT THIS MORNING.
GIVEN EXTENT OF THIS STRATUS DECK AND RECENT MODEL
PERFORMANCE...KEPT OVERCAST SKIES THROUGH THE NIGHT. THIS IS SIMILAR
TO THE LATEST RAP...WHICH SEEMS TO HAVE A DECENT HANDLE ON THINGS.
STAYED AWAY FROM COLDEST MODELS FOR LOWS AGAIN TONIGHT...WITH THE
CLOUDS EXPECTED TO HANG AROUND.
BIG ISSUE TOMORROW IS WEAK SHORTWAVE AND SFC LOW EXPECTED TO SLIDE
THROUGH THE AREA. MODELS ARE IN BETTER AGREEMENT WITH THE TRACK OF
THIS SYSTEM...BUT THE NAM CONTINUES WITH A FARTHER NORTH SOLUTION
THAN OTHER MODELS. LEANED TOWARD THE SOUTHERN SOLUTION...BUT DID
LEAVE A LITTLE INFLUENCE FROM NAM POSSIBILITY. LATEST NAM HAS
SHIFTED A BIT SOUTH...WHICH IS ENCOURAGING THAT MAYBE SOUTHERN
SOLUTION...OR AT LEAST A BLEND OF SOLUTIONS...WAS THE WAY TO GO.
EITHER WAY...DOES NOT LOOK LIKE A TON OF PRECIP WITH THIS ONE. WILL
PROBABLY BE ALL SNOW IN THE MORNING WITH COLDER TEMPS...POSSIBLY
MIXING WITH RAIN IN THE AFTERNOON AS IT WARMS UP A BIT. NOT
EXPECTING MUCH MORE THAN A COUPLE TENTHS OF AN INCH OF SNOW. THE
BEST CHANCE FOR MEASURABLE WILL BE FROM MADISON WESTWARD WHERE IT
WILL BE COLDER WHEN THE PRECIP MOVES IN.
.TUESDAY NIGHT THROUGH WEDNESDAY...FORECAST CONFIDENCE IS HIGH.
QUIET THIS PERIOD AS WE WAIT FOR THE ARRIVAL OF THE WINTER STORM
FOR THE WESTERN GREAT LAKES. THE LOW DRIFTING THROUGH ON TUESDAY
MAY STILL HAVE SOME LIGHT RAIN/SNOW LINGERING NORTH OF PORT
WASHINGTON AS IT PEELS OFF TO THE EAST EARLY IN THE EVENING.
THE GFS IS THE FASTEST WITH THE ARRIVAL OF PRECIP AHEAD OF THE
STORM ON WEDNESDAY...SPREADING IT ACROSS THE ENTIRE CWA BY 6PM ON
WEDNESDAY. THIS IS AN OUTLIER AND WILL LIMIT ANY AFTERNOON PRECIP
CHANCES TO THE AREA SOUTHWEST OF MADISON.
.WEDNESDAY NIGHT INTO THURSDAY NIGHT...FORECAST CONFIDENCE IS
MEDIUM TO HIGH.
WE ISSUED A WINTER STORM WATCH EARLIER IN THE DAY FOR THE AREA WE
HAD THE HIGHEST CONFIDENCE OF HEAVY SNOW. THIS AREA IS WITHIN THE
OVERLAP REGION OF MOST OF THE THE MODEL SOLUTIONS. I WOULD EXPECT
ADJUSTMENTS TO THIS WATCH OVER THE NEXT FEW FORECAST CYCLES AS THE
MODELS BEGIN TO SETTLE DOWN AND HONE IN ON A CONSENSUS SOLUTION.
HERE/S THE LATEST ON OUR MODEL SUITE THAT CAME IN THIS MORNING.
THE NAM TOOK A 160 MILE SHIFT SOUTH WITH THE 12Z RUN..GOING FROM
THE MOST NORTHERN AND WARM SOLUTION...TO ONE VERY SIMILAR TO THE
GFS. THE GFS DIDN/T CHANGE VERY MUCH...IF ANYTHING IT MOVED A
NOTCH NORTH AND LOOKS WARMER IN IT/S CRITICAL 0-5000FT THERMAL
PROFILE. THE GEM /CANADIAN/ HAS PICKED UP SPEED AND DOESN/T
INTENSIFY UNTIL IT GETS EAST OF US. THE TRACK IS MORE OR LESS
UNCHANGED. AND FINALLY...THE ECMWF /EUROPEAN/ IS STEADY AS CAN
BE...NOT BUDGING MUCH AT ALL IN ITS TRACK. THE ECMWF IS THE MODEL
WITH THE MOST SOUTHERN SOLUTION. IT WOULD BRING MORE SNOW TO THE
SOUTHEAST FORECAST AREA COMPARED TO THE WESTERN AREA.
THE DYNAMIC/FORCING PROFILE HASN/T CHANGED FROM THE OVERNIGHT
INTERPRETATION. THE UPPER SYSTEM IS STILL GOING NEGATIVE TILT AND
INTENSIFYING AS IT MOVES INTO WISCONSIN. THIS WILL CAUSE THE
SURFACE LOW TO DEEPEN RAPIDLY AS IT MOVES INTO NORTHERN
ILLINOIS...VS INTENSIFYING EAST OF US. THIS MAKES THE STORM EVEN
MORE UNTRUSTWORTHY AND DANGEROUS. COLUMN COOLING CAN HAPPEN MUCH
FASTER THAN EXPECTED. THE OMEGA FORCING WITHIN THE DENDRITE
REGION...CROSS-HAIRS...EXPLODES FOR A TIME...HIGHLIGHTING SOME
PRETTY HEAVY SNOW POTENTIAL CENTERED AROUND 12Z THURSDAY MORNING.
THE POTENTIAL FOR THUNDER SNOW IS LOOKING VERY GOOD. QEPV CHARTS
AND SOUNDING ANALYSIS ARE SHOWING LOTS OF POTENTIAL FROM 750MB UP
THROUGH 500MB. PRETTY STEEP LAPSE RATES FOR THIS TIME OF YEAR.
PRECIPITABLE WATER VALUES OFF THE NAM AND THE GFS ARE ALMOST TOO
HIGH...REACHING ABOUT .75 INCH...WHICH IS ABOUT 2 STANDARD
DEVIATIONS ABOVE CLIMO. TYPICAL BIG SNOWSTORMS IN DECEMBER HAVE A
PW OF AROUND .4 TO .5. THIS SPEAKS TO THE WARMTH OF THE NAM AND
GFS. QPF AMOUNTS ARE STILL AROUND 1 INCH. SO...WHERE IT WILL BE ALL
SNOW...THIS MEANS WE COULD SEE SNOW ACCUMS PUSHING 12 INCHES NORTH
AND WEST OF MADISON. BUT...THIS IS FOLLOWING MORE OF A NAM/GFS/EC
BLEND. IF THE MODELS COME IN CLOSER TO THE ECMWF SOUTHERN
SOLUTION...EXPECT MORE SNOW TO THE SOUTHEAST.
WINDS WILL CRANK UP BY LATE MORNING ON THURSDAY WITH GUSTS
POSSIBLY HITTING 35 MPH. THIS COULD LEAD TO BLIZZARD OR NEAR
BLIZZARD CONDITIONS.
EXPECT THE SNOW TO BEGIN WINDING DOWN FROM WEST TO EAST THURSDAY
AFTERNOON INTO THE EVENING. EXPECT WINDS TO STAY UP INTO THE
EVENING...THEN SLOWLY DIMINISH.
.FRIDAY THROUGH MONDAY...FORECAST CONFIDENCE IS HIGH.
COLD HIGH PRESSURE SETTLES IN. LOOKS PRETTY QUIET AND CHILLY THIS
PERIOD.
&&
.AVIATION/00Z TAFS/...
MAINLY MVFR CIGS CONTINUE ACROSS SOUTHERN WISCONSIN. MODELS CONTINUE
TO TRY AND SCATTER THINGS OUT...BUT JUST IS NOT HAPPENING.
CONSIDERING KEEPING THE MVFR STRATUS GOING RIGHT THROUGH THE NIGHT
PER THE LATEST RAP RUN.
LOW PRESSURE WILL SLIDE THROUGH SOUTHERN WISCONSIN
TOMORROW...BRINGING A CHANCE FOR RAIN/SNOW SHOWERS. IF CONDITIONS
HAVE ACTUALLY IMPROVED BY THEN...MAY SEE CIGS GO BACK DOWN AS THE
LOW SLIDES THROUGH. NOT EXPECTING MUCH IN THE WAY OF SNOW
ACCUMULATIONS...BUT COULD SEE A COUPLE TENTHS OF AN INCH. BEST
CHANCE FOR ANY ACCUMULATION WOULD BE FROM MADISON WESTWARD...AS IT
WILL BE COLDER THERE WHEN THE PRECIP MOVES IN.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR WIZ046-047-051-056>058-062-063-067.
LM...NONE.
&&
$$
TONIGHT/TUESDAY AND AVIATION/MARINE...DDV
TUESDAY NIGHT THROUGH MONDAY...DAVIS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
303 PM CST MON DEC 17 2012
.SHORT TERM...TONIGHT THROUGH THURSDAY
303 PM CST MON DEC 17 2012
MAIN FORECAST CONCERNS ARE ON BRIEF LIGHT SNOW EVENT TOMORROW AND
THE POSSIBLE WINTER STORM LATE WEDNESDAY INTO THURSDAY.
CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING FROM THE GULF OF ALASKA TO OFF THE PACIFIC
NORTHWEST...A RELATIVELY POTENT SHORTWAVE CROSSING THE NORTHERN
ROCKIES...A WEAK NORTH TO SOUTH ORIENTED SHORTWAVE OVER THE FAR
EASTERN DAKOTAS AND A WEAK RIDGE SANDWICHED IN-BETWEEN THESE
SHORTWAVES. MID LEVEL CLOUDS WERE ASSOCIATED AHEAD OF THE DAKOTAS
SHORTWAVE...WITH A FEW FLURRIES FALLING OUT OF THESE OVER SOUTHWEST
MINNESOTA AND NORTHWEST IOWA. OVER THE FORECAST AREA...STRATUS
PERSISTS...BURIED UNDERNEATH A SUBSIDENCE INVERSION SEEN ON THE 12Z
MPX...GRB AND DVN SOUNDINGS. HAVING LIGHT WINDS ASSOCIATED WITH HIGH
PRESSURE AT THE SURFACE COMBINED WITH BEING AT THE BOTTOM OF THE
DAYLIGHT CYCLE HAS NOT HELPED EITHER TO GET RID OF THE STRATUS.
TEMPERATURES AS A RESULT HAVE NOT CLIMBED A WHOLE LOT FROM MORNING
LOWS. THE STRATUS ACTUALLY EXTENDS WEST ALL THE WAY INTO THE CENTRAL
DAKOTAS. FARTHER WEST...LEE TROUGHING HAS FORMED DOWNSTREAM OF THE
NORTHERN ROCKIES SHORTWAVE...ALSO AIDED BY A 130KT JET NEAR THE
TROPOPAUSE ON THE SOUTH SIDE OF THE SHORTWAVE. THERE HAS BEEN QUITE
A BIT OF PRECIPITATION ACROSS THE NORTHERN ROCKIES AS WELL AS THE
UPPER JET DRIVES IN PACIFIC MOISTURE.
TONIGHT AND TUESDAY...FOCUS IS ON THAT NORTHERN ROCKIES SHORTWAVE.
MODELS ARE IN REALLY GOOD AGREEMENT BRING THE SHORTWAVE INTO
SOUTHERN SOUTH DAKOTA BY 06Z...NEAR SIOUX CITY IOWA BY 12Z...NEAR
DUBUQUE BY 18Z AND CHICAGO BY 00Z. THIS TRACK IS A BIT FARTHER SOUTH
THAN SUGGESTED OVER THE PAST FEW DAYS...WITH PERHAPS THE CANADIAN
AND ECMWF DOING THE BEST JOB ON IT. THE SHORTWAVE AND THE ASSOCIATED
UPPER JET SOUTH OF IT ARE STRONG ENOUGH THAT OUT OF THE CURRENT LEE
TROUGHING A SURFACE LOW IS SUGGESTED TO DEVELOP. THIS LOW OF COURSE
ENDS UP TRACKING WITH THE SHORTWAVE...RESULTING IN A LOW TO
MID-LEVEL FRONTOGENESIS ZONE ON THE NORTH SIDE OF IT. MOISTURE
INITIALLY IS LIMITED...NOTED BY THE CURRENT LACK OF MID-CLOUDS
ACROSS MUCH OF THE PLAINS. HOWEVER...AS WE GO THROUGH TONIGHT...
CONDENSATION PRESSURE DEFICITS ON THE 285-290K SURFACES DECREASE AS
THE LIFT HELPS TO SATURATE THE MID-LEVELS OF THE ATMOSPHERE. SHOULD
SEE A BAND OF LIGHT SNOW BREAK OUT ACROSS SOUTH DAKOTA INTO SOUTHERN
MINNESOTA AND NORTHERN IOWA BY LATE TONIGHT...ON THE NORTH SIDE OF
THE LOW. PERHAPS SOME OF THIS SNOW SQUEAKS INTO WESTERN PORTIONS OF
THE FORECAST AREA TOWARDS 12Z. WITH THE TREND FARTHER SOUTH WITH THE
SHORTWAVE TRACK...HAVE LEANED THE FORECAST MORE TOWARDS THE 17.12Z
GFS/ECMWF IDEA VERSUS THE FARTHER NORTH BUT TRENDING SOUTH 17.12Z
NAM FOR TUESDAY. THE FRONTOGENESIS BAND OF SNOW SHOULD AFFECT MAINLY
I-90 SOUTH AND RAISED PRECIPITATION CHANCES TOWARDS 60 IN THIS AREA.
LIMITED MOISTURE NOTED BY MIXING RATIOS OF 2-3 G/KG ON THE 285-290K
SURFACES WILL KEEP QPF AMOUNTS DOWN TO AT MOST A 0.10 OF AN INCH
TOTAL LIQUID EQUIVALENT. THE LIFT IS PRIMARILY CENTERED BELOW THE
DENDRITIC GROWTH ZONE...KEEPING SNOW TO WATER RATIOS DOWN NEAR 10 TO
1...THUS ONLY UP TO AN INCH OF SNOW IS ANTICIPATED. CONCERN THOUGH
IS THAT THE SNOW IS COMING AT MORNING COMMUTE TIME...SO HAVE ISSUED
AN SPS TO ACCOUNT FOR THIS. PLENTY OF CLOUDS LOOK TO PERSIST THROUGH
THIS PERIOD THUS AGAIN TEMPERATURES IMPACTED BY ADVECTION. WITH THE
FARTHER SOUTH TRACK OF THE LOW...HAVE COOLED HIGHS DOWN FOR TUESDAY.
TUESDAY NIGHT THROUGH THURSDAY...ALL ATTENTION IS ON THE WINTER
STORM POTENTIAL...WHICH RELATES TO THE CURRENT TROUGH OFF THE
PACIFIC NORTHWEST. THAT TROUGH IS COMPOSED OF 2 PARTS...A POTENT
SHORTWAVE NEAR 42N 140 W...AND A COLD SHORTWAVE NEAR THE NORTHERN
BRITISH COLUMBIA COAST. 500MB TEMPS WERE AROUND -40C WITH THE COLD
SHORTWAVE...AND JUST AHEAD OF IT OVER NORTHERN BRITISH COLUMBIA
850MB TEMPS ARE IN THE -15 TO -25C RANGE. THE IDEA SHOWN FOR THE
PAST MANY DAYS IS THAT THESE TWO PARTS ARE EVENTUALLY GOING TO PHASE
UP AFTER CROSSING THE WESTERN U.S....RESULTING IN A DEEPENING WINTER
STORM FROM THE CENTRAL PLAINS INTO THE GREAT LAKES. THE QUESTION HAS
BEEN WHERE DOES THE PHASING OCCUR WITH RESPECT TO OUR LONGITUDE TO
HELP DETERMINE THE EXACT TRACK AND SPEED. THE ANSWER STILL IS NOT
THERE YET...HOWEVER...THE DETERMINISTIC MODEL SPREAD IS SHRINKING
AND SHOULD CONTINUE TO DO SO OVER THE NEXT FEW DAYS AS THE TROUGH
COMES INTO THE WESTERN U.S.. WITH THE 17.12Z MODEL GUIDANCE...TRACK
SPREAD RANGES FROM THE NORTHWEST SOLUTION OF THE NAM TO THE
SOUTHEAST SOLUTION OF THE ECMWF. THE GFS...UKMET AND CANADIAN LIE
IN-BETWEEN. THE NAM HAS BEEN TRENDING SOUTHEAST...THE GFS NORTHWEST
AND THE CANADIAN/ECMWF STAYING FAIRLY CLOSE. THE FORECAST FOLLOWS A
BLEND OF THE GFS...CANADIAN AND ECMWF SCENARIOS SINCE THESE SEEM TO
BE THE MOST LIKELY TO OCCUR GIVEN TRENDS. FOR WHAT ITS WORTH...THE
PAST 4 SREF RUNS ARE VERY CONSISTENT ON A FARTHER NORTHWEST TRACK
CLOSE TO OR EVEN MORE NORTHWEST THAN THE NAM. NEEDLESS TO SAY...
STILL PLENTY OF UNCERTAINTY.
SOME DETAILS...TUESDAY NIGHT INTO WEDNESDAY MORNING SHOULD STAY DRY
AS WE ARE IN-BETWEEN SYSTEMS. BIG QUESTION MARK IS IF WE CAN CLEAR.
MOST MODELS SAY WE CAN...BUT HAVING SNOW ON TUESDAY COMBINED WITH
MODELS NOT DOING THE GREATEST ON THE CURRENT STRATUS YIELDS A MORE
PESSIMISTIC VIEW. AS SUCH...HAVE INCREASED CLOUD COVER AND FURTHER
INCREASES MAY BE NECESSARY. AS THE STORM SYSTEM DEEPENS IN THE
SOUTHERN PLAINS ON WEDNESDAY...A BAND OF FRONTOGENESIS
DEVELOPS/STRENGTHENS UP INTO OUR REGION. THE GFS AND CANADIAN
PRODUCE PRECIPITATION IN THE AFTERNOON AS THEY ARE QUICKER TO
SATURATE THE LOW LEVELS AND TO BRING IN THE FORCING...COMPARED TO
THE ECMWF/NAM/UKMET. HARD TO SAY WHICH GROUP MAY BE MORE CORRECT AT
THIS POINT...THOUGH THE MORE CONSISTENT SIGNAL HAS BEEN TO WAIT
UNTIL WEDNESDAY EVENING TO BRING THE PRECIPITATION IN. THUS...FOR
NOW JUST INCLUDED 20-40 PERCENT CHANCES FROM I-90 SOUTH FOR THE
AFTERNOON. THE MAJORITY OF THE FORECAST AREA SHOULD SEE
PRECIPITATION WEDNESDAY NIGHT INTO THURSDAY MORNING...NO MATTER WHAT
MODEL SOLUTION IS FOLLOWED. IF THERE IS ANYWHERE OF CONCERN DURING
THIS PERIOD THAT MAY NOT SEE PRECIPITATION IT IS OUR FAR NORTHWEST
AS INDICATED BY THE ECMWF. THUS...HIGHEST CHANCES UP AT OR NEAR 100
ARE CONFINED TO THE SOUTHEAST HALF. PRECIPITATION SHOULD START TO
DIMINISH THURSDAY AFTERNOON AS THE SYSTEM HEADS OFF INTO LOWER
MICHIGAN.
IMPACTS/CONCERNS TO WORRY ABOUT WITH THIS WINTER STORM INCLUDE:
1. HEAVY SNOW...PRETTY GOOD MODEL CONSENSUS EXISTS THAT THE TIME
PERIOD WOULD BE WEDNESDAY NIGHT INTO THURSDAY MORNING. EXACT
PLACEMENT OF HEAVIEST SNOW IS STILL UNCERTAIN...BUT FOLLOWING THE
AFOREMENTIONED GFS/ECMWF/CANADIAN BLEND PLACES IT IN THE
SOUTHEASTERN HALF OF THE FORECAST AREA. WITH MAYBE 100 MB OF
DENDRITIC GROWTH AT MOST AND FAIRLY HIGH UP SAY BETWEEN
550-650MB...THE SNOW TO WATER RATIOS SHOULD BE TYPICAL...IN THE
10-15 TO 1 RANGE.
2. MIXED PRECIPITATION TYPES...MODEL CONSENSUS HAS BEEN TO KEEP THE
SYSTEM OFF TO OUR SOUTHEAST...KEEPING OUR AREA IN THE DEEPER COLD
AIR AND THUS SNOW AS THE MAJORITY PRECIPITATION TYPE. HOWEVER...THE
GFS SUGGESTS THAT IF THE SYSTEM CAN WRAP UP ENOUGH...EVEN GRANT AND
CLAYTON COUNTIES COULD END UP WITH SLEET OR RAIN FOR A TIME.
3. BLOWING SNOW/WIND...AS THE SYSTEM DEEPENS ON ITS WAY UP THROUGH
ILLINOIS WEDNESDAY NIGHT AND BEGINS TO PULL AWAY FROM THE AREA ON
THURSDAY...THE PRESSURE GRADIENT TIGHTENS...CAUSING NORTHWEST WINDS
TO INCREASE. THESE WINDS COULD EASILY REACH THE 15-25KT RANGE WITH
HIGHER GUSTS. COMBINING THESE WITH FALLING OR ALREADY ON THE GROUND
SNOW WOULD YIELD BLOWING SNOW...ESPECIALLY ACROSS NORTHEAST IOWA
WHICH HAS THE MOST EXPOSED TERRAIN.
WITH THE NARROWING MODEL SPREAD...ENOUGH CONFIDENCE EXISTED EARLIER
TODAY TO ISSUE A WINTER STORM WATCH FOR ABOUT THE SOUTHEASTERN HALF
OF THE FORECAST AREA. NOTE THAT THE WATCH AREA MAY NOT END UP BEING
THE FINAL WARNING AREA...THUS THE PHRASE WATCH. FURTHER REFINEMENTS
MAY OCCUR...ESPECIALLY ONCE CONFIDENCE INCREASES ENOUGH TO CHANGE
THE WATCHES TO ADVISORIES/WARNINGS.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
303 PM CST MON DEC 17 2012
MAIN FORECAST CONCERNS ARE TEMPERATURES THROUGH FORECAST PERIOD.
THE DETERMINISTIC 17.12Z GFS/ECMWF/GEM ARE IN GOOD AGREEMENT WITH
UPPER LEVEL TROUGH OVER THE NORTHEASTERN UNITED STATES AND UPPER
LEVEL RIDGE OVER THE EASTERN ROCKY MOUNTAINS THROUGH 18Z
SATURDAY...THEN THE MODELS BEGIN TO DIVERGE ON STRENGTH OF THE
UPPER LEVEL TROUGH OVER THE NORTHEASTERN UNITED STATES AND UPPER
LEVEL RIDGE OVER THE ROCKY MOUNTAINS. THE 17.12Z ECMWF IS MORE
AMPLIFIED WITH THE UPPER LEVEL TROUGH SATURDAY NIGHT INTO MONDAY
THAN THE 17.12Z GFS/GEM. IF THIS OCCURS...THE UPPER MIDWEST AND
GREAT LAKES REGION WILL REMAIN UNDER NORTHERLY FLOW ALOFT AND A
COLDER AIRMASS WILL FILTER INTO THE AREA. THIS WILL HAVE IMPACTS
ON TEMPERATURES...ESPECIALLY SATURDAY NIGHT INTO MONDAY. THE
17.12Z GFS INDICATES WEST TO EAST ZONAL FLOW ACROSS THE UNITED
STATES AND SLIGHTLY WARMER TEMPERATURES THAN THE 17.12Z ECMWF.
THIS WOULD RESULT IN NEAR NORMAL TEMPERATURES ACROSS FORECAST
AREA. AT THIS TIME...WILL CONTINUE WITH A CONSENSUS BLEND OF
TEMPERATURES...BASED ON THE LOW CONFIDENCE OF UPPER LEVEL FLOW
PATTERN AFTER 18Z SATURDAY.
NO REAL INDICATION OF ANY PRECIPITATION OCCURRING AS THE UPPER
FLOW PATTERN PROGGED IS MOSTLY SUBSIDENT...FAVORING HIGH PRESSURE
AT THE SURFACE.
&&
.AVIATION...THROUGH 18Z TUESDAY
1224 PM CST MON DEC 17 2012
A BROAD EXPANSIVE IFR CLOUD DECK IS IN PLACE OVER THE REGION WITH
SOME SMALL HOLES OF VFR OVER PARTS OF SOUTHWEST MN AND
NORTH CENTRAL IA. HAVE DECIDED TO TAKE A MORE PESSIMISTIC FORECAST
IN THE TAFS WITH NO LARGE CHANGE SEEN IN THE WEATHER PATTERN
OVERNIGHT. HAVE INCLUDED A TEMPO GROUP TO INDICATE THE
POSSIBILITY THAT A FEW BREAKS MAY MOVE INTO THE TAF SITES BUT IT
WILL BE SHORTER LIVED OVERNIGHT.
A WEATHER SYSTEM SHIFTING ACROSS THE AREA ON TUESDAY WILL PROVIDE
LIGHT SNOW AND IFR CONDITIONS TO THE AREA IT IMPACTS. THE SNOW
BAND COULD BE QUITE NARROW WHICH HOLDS THE POTENTIAL TO MISS THE
AIRPORTS. HOWEVER...CONFIDENCE IS HIGH ENOUGH TO PLACE IFR SNOW IN
THE TUESDAY MORNING FORECAST. THIS CAN BE FURTHER REFINED IN
FUTURE TAF ISSUANCES. THE LIGHT SNOW IS EXPECTED TO END IN THE
AFTERNOON FROM WEST TO EAST ACROSS THE AREA.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
303 PM CST MON DEC 17 2012
WI...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR WIZ034-041>044-053>055-061.
MN...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR MNZ096.
IA...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR IAZ010-011-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...DTJ/AJ
AVIATION...BAUMGARDT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
533 AM CST MON DEC 17 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
329 AM CST MON DEC 17 2012
THE MAIN FOCUS FOR THE EARLY PORTION OF THE WEEK IS WITH THE
POTENTIAL FOR LIGHT SNOW ON TUESDAY FOLLOWED BY THE BEGINNING OF A
POSSIBLE WINTER STORM ON WEDNESDAY NIGHT.
CURRENTLY...EXTENSIVE CLOUD COVER REACHES FROM THE GREAT LAKES
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY TO THE DAKOTAS BEFORE
CLEARING TO THE SOUTHWEST ALONG A WARM FRONT THAT EXTENDS FROM A
LOW IN FAR SOUTHEAST MONTANA THROUGH CENTRAL NEBRASKA. WINDS WILL
BE OUT OF THE NORTHWEST THROUGH MUCH OF TODAY WITH A SURFACE LOW
IN THE CENTRAL GREAT LAKES AND A RIDGE OF HIGH PRESSURE MOVING
ACROSS MINNESOTA. 17.00Z NAM/GFS AND 17.06Z RAP SOUNDINGS SHOW A
PERSISTENTLY STRONG INVERSION CENTERED ON 900MB THAT SHOULD KEEP
THE LOW LEVEL MOISTURE TRAPPED UNDERNEATH IT THROUGH THE DAY AND
SKIES ON THE CLOUDIER SIDE. THE SATURATED PORTION OF THIS PROFILE
DOES DIP DOWN TO AROUND -10C...SO THERE COULD BE SOME ICE THAT
DEVELOPS IF ANY LOW LEVEL LIFT CAN HELP TO PRODUCE SOME FLURRIES.
SOME RADAR RETURNS AND SURFACE OBS ARE REPORTING -SN OUT IN THE
SIOUX FALLS AREA CLOSER TO A WEAKENING AREA OF LOW PRESSURE...BUT
AM EXPECTING THAT AS THIS LOW TRIES TO RUN INTO THE RIDGE THAT IT
SHOULD LOSE MUCH OF ITS LOW LEVEL LIFT AND THAT THERE WONT BE MUCH
LEFT TO IT AS IT APPROACHES THE AREA.
A WEAK MID LEVEL SHORT WAVE TROUGH BREAKS TO THE EAST OF A CLOSED
LOW CURRENTLY IN THE PACIFIC NORTHWEST AND HELPS TO FORM AN
ELONGATED WEST TO EAST TROUGH THAT EXTENDS FROM THE DAKOTAS INTO
THE GREAT LAKES LATE TONIGHT INTO TOMORROW. THIS FEATURE WILL
PRODUCE SOME SLIGHTLY BETTER MID LEVEL LIFT THAT WILL BE AIDED BY
A PAIR OF SURFACE LOWS THAT WILL PROPAGATE EAST ALONG WITH IT. THE
NORTHERN SURFACE LOW WILL STICK TO THE DAKOTAS...BUT A SOUTHERN
LOW IS FORECAST TO TRACK ACROSS NORTHERN IOWA INTO SOUTHERN
WISCONSIN ON TUESDAY AND SHOULD PROVIDE SOME BETTER LIFT TO
DEVELOP A BAND OF PRECIPITATION TO THE NORTHEAST SIDE OF IT. THE
QG FORCING FROM THE MID LEVEL TROUGH APPEARS TO BE SLIGHTLY OFF
TIMING-WISE FROM THE LOW LEVEL FRONTOGENESIS TO WHERE THE
FORCING/MOISTURE IS NOT PARTICULARLY DEEP. THIS IS LIKELY WHY QPF
AMOUNTS ARE NOT MORE THAN A FEW HUNDREDTHS OF AN INCH WITH THIS
SYSTEM. SNOWFALL TOTALS WILL LIKELY BE SOMEWHERE IN THE HALF INCH
TO INCH RANGE WITH THE HIGHER TOTALS MORE LIKELY ACROSS SOUTHEAST
MINNESOTA AND WEST CENTRAL WISCONSIN WHERE THE PRECIPITATION TYPE
WILL REMAIN SNOW THROUGH THE DAY WHILE SOME RAIN COULD MIX IN
ACROSS NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THE DENDRITIC
GROWTH ZONE REMAINS FAIRLY SMALL AT LESS THAN A 100MB THROUGHOUT
THE DAY...SO AM NOT EXPECTING VERY HIGH SNOW TO LIQUID RATIOS FOR
THIS EVENT.
SKIES SHOULD CLEAR OUT TUESDAY NIGHT AS THE FRONT/TROUGH MOVES
THROUGH AND A RIDGE OF HIGH PRESSURE PUSHES IN FROM THE WEST. THIS
WILL SET THE STAGE FOR THE INITIAL STAGES OF A WINTER STORM THAT
WILL LIKELY AFFECT SOME OR ALL OF THE REGION. THE INITIAL BAND OF
PRECIPITATION WILL DEVELOP WEDNESDAY AFTERNOON ACROSS IOWA DUE TO
STRONG LOW LEVEL FRONTOGENETIC FORCING AS THE MAIN MID LEVEL
TROUGH ENTERS THE SOUTHERN PLAINS AND THE SURFACE LOW STARTS TO
DEEPEN IN THE SOUTHERN PLAINS. SOME DIFFERENCES ALREADY START TO
ARISE WEDNESDAY AFTERNOON BETWEEN THE 17.00Z MODEL RUNS WITH THE
ECMWF BEING THE SLOWEST TO BRING THE FRONTOGENETIC BAND INTO IOWA
WHILE THE GFS STRETCHES QPF ALL THE WAY INTO SOUTHWEST MICHIGAN.
THE NAM SHOWS A DRIER SOLUTION THAN WHAT THE GFS IS ADVERTISING
AND IS FURTHER TO THE WEST TO START OUT ON WEDNESDAY AFTERNOON.
WENT MAINLY WITH A 17.00Z GFS/ECMWF BLEND OVER THIS PERIOD AND
KEPT THE PRECIPITATION CHANCES MAINLY IN NORTHEAST IOWA. THE MID
LEVEL TROUGH THEN BEGINS TO CLOSE OFF WEDNESDAY NIGHT WITH THE
SURFACE LOW DEEPENING. THE OVERALL RESULT OF WHAT THE 17.00Z...AND
MANY PREVIOUS RUNS...PRODUCE IS A MAJOR WINTER STORM THAT MOVES
THROUGH THE GREAT LAKES REGION. THE QUESTION AT THIS POINT IS
WHERE THE CORE OF THE TROUGH/SURFACE LOW WILL TRACK.
TO START OUT...THE 17.00Z AND 17.06Z NAM ARE WARM/DEEP OUTLIERS IN
COMPARISON TO THE 17.00Z AND PREVIOUS RUNS OF THE ECMWF/GFS/GEM WITH
TAKING THE SURFACE LOW UP ALONG THE MISSISSIPPI RIVER. THE 17.06Z
RUN DOES APPEAR TO BE TRENDING A LITTLE TO THE EAST...BUT IS STILL
TOO FAR ON THE WEST SIDE OF THE TRACKS TO BE CONSIDERED. WITH MANY
OF THE SREF MEMBERS USING THE NAM...IT ALSO APPEARS TO BE HEAVILY
SKEWED BY IT AND IS TOO FAR WEST AS WELL WITH ITS QPF/LOW TRACK.
THE HIGHEST CONFIDENCE HAS TO BE PLACED WITH THE ECMWF WHICH HAS
BEEN NEARLY IDENTICAL FOR THE PAST 4 RUNS IN REGARD TO TIMING AND
PLACEMENT OF THE SURFACE LOW AND HEAVIEST SNOW BAND. THIS SOLUTION
TAKES THE LOW FROM ST LOUIS TOWARD NORTHERN INDIANA AND DETROIT
WITH THE HEAVIEST SNOW BAND GOING FROM EASTERN IOWA TO SOUTHEAST
WISCONSIN. THE GFS IS NOT TOO FAR OFF FROM THIS SOLUTION...BUT IS
A LITTLE FURTHER WEST OF THIS TRACK AND FASTER WITH THE LOW WHILE
THE GEM IS SOMEWHERE IN BETWEEN THE TWO.
FAVORED THE 17.00Z ECMWF WITH THIS FORECAST...SO WHILE CONFIDENCE
IS RATHER HIGH THAT THIS WINTER STORM WILL OCCUR...THE CONFIDENCE
IS NOT HIGH ENOUGH IN WHERE THE HEAVIEST SNOW BAND WILL END UP TO
ISSUE A LONG LEAD TIME WINTER STORM WATCH. PARTICULARLY SO SINCE
THE ECMWF TAKES THE HIGHER SNOW TOTALS TO THE EAST OF THE FORECAST
AREA. THE COUNTIES THAT ARE MOST LIKELY UNDER THE THREAT OF THE
HEAVIEST SNOWS ARE FROM JUNEAU/ADAMS COUNTIES IN WISCONSIN DOWN TO
CLAYTON COUNTY IN IOWA BASED ON THESE 17.00Z ECMWF/GFS/GEM
RESULTS.
.LONG TERM...THURSDAY THROUGH SUNDAY
329 AM CST MON DEC 17 2012
THE STORM WILL CONTINUE INTO THURSDAY...BUT HOW FAR WEST THE SNOW
LINGERS IS THE MAIN QUESTION. PERHAPS THE BIGGER ISSUE WILL BE
WITH THE STRONG WINDS THAT ACCOMPANY THIS STORM THAT SHOULD LEAD
TO SOME BLOWING SNOW WITH SUSTAINED WINDS REACHING 25 MPH AND
LIKELY GUSTING ABOVE 30 MPH. BY THURSDAY NIGHT...THE STORM WILL
LIKELY HAVE ENDED ACROSS WESTERN WISCONSIN WITH HIGH PRESSURE
PUSHING DOWN FROM SOUTH CENTRAL CANADA. THIS RIDGE WILL REMAIN IN
PLACE THROUGH NEXT WEEKEND AND WILL...ALONG WITH THE FRESH
SNOW PACK...PROVIDE FOR COLD AND DRY CONDITIONS WITH LOWS DROPPING
DOWN INTO THE SINGLE DIGITS.
&&
.AVIATION...TODAY AND TONIGHT
531 AM CST MON DEC 17 2012
LOW CLOUDS WILL REMAIN TRAPPED BELOW A SUBSIDENCE INVERSION
THROUGH EARLY THIS EVENING. CEILINGS WILL CONTINUE TO BE LIFR/IFR AT
KRST AND MVFR AT KLSE. AS A LOW PRESSURE SYSTEM APPROACHES THE
REGION...THE INVERSION WILL BREAK BETWEEN 18.02Z AND 18.08Z. THIS
WILL RESULT IN THE CEILINGS CLIMBING INTO THE 4 TO 5K RANGE FOR A
COUPLE OF HOURS...AND THEN ONCE AGAIN BECOME MVFR AS THE CLOUDS
LOWER AHEAD OF APPROACHING LOW PRESSURE SYSTEM.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
329 AM CST MON DEC 17 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
329 AM CST MON DEC 17 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
329 AM CST MON DEC 17 2012
THE MAIN FOCUS FOR THE EARLY PORTION OF THE WEEK IS WITH THE
POTENTIAL FOR LIGHT SNOW ON TUESDAY FOLLOWED BY THE BEGINNING OF A
POSSIBLE WINTER STORM ON WEDNESDAY NIGHT.
CURRENTLY...EXTENSIVE CLOUD COVER REACHES FROM THE GREAT LAKES
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY TO THE DAKOTAS BEFORE
CLEARING TO THE SOUTHWEST ALONG A WARM FRONT THAT EXTENDS FROM A
LOW IN FAR SOUTHEAST MONTANA THROUGH CENTRAL NEBRASKA. WINDS WILL
BE OUT OF THE NORTHWEST THROUGH MUCH OF TODAY WITH A SURFACE LOW
IN THE CENTRAL GREAT LAKES AND A RIDGE OF HIGH PRESSURE MOVING
ACROSS MINNESOTA. 17.00Z NAM/GFS AND 17.06Z RAP SOUNDINGS SHOW A
PERSISTENTLY STRONG INVERSION CENTERED ON 900MB THAT SHOULD KEEP
THE LOW LEVEL MOISTURE TRAPPED UNDERNEATH IT THROUGH THE DAY AND
SKIES ON THE CLOUDIER SIDE. THE SATURATED PORTION OF THIS PROFILE
DOES DIP DOWN TO AROUND -10C...SO THERE COULD BE SOME ICE THAT
DEVELOPS IF ANY LOW LEVEL LIFT CAN HELP TO PRODUCE SOME FLURRIES.
SOME RADAR RETURNS AND SURFACE OBS ARE REPORTING -SN OUT IN THE
SIOUX FALLS AREA CLOSER TO A WEAKENING AREA OF LOW PRESSURE...BUT
AM EXPECTING THAT AS THIS LOW TRIES TO RUN INTO THE RIDGE THAT IT
SHOULD LOSE MUCH OF ITS LOW LEVEL LIFT AND THAT THERE WONT BE MUCH
LEFT TO IT AS IT APPROACHES THE AREA.
A WEAK MID LEVEL SHORT WAVE TROUGH BREAKS TO THE EAST OF A CLOSED
LOW CURRENTLY IN THE PACIFIC NORTHWEST AND HELPS TO FORM AN
ELONGATED WEST TO EAST TROUGH THAT EXTENDS FROM THE DAKOTAS INTO
THE GREAT LAKES LATE TONIGHT INTO TOMORROW. THIS FEATURE WILL
PRODUCE SOME SLIGHTLY BETTER MID LEVEL LIFT THAT WILL BE AIDED BY
A PAIR OF SURFACE LOWS THAT WILL PROPAGATE EAST ALONG WITH IT. THE
NORTHERN SURFACE LOW WILL STICK TO THE DAKOTAS...BUT A SOUTHERN
LOW IS FORECAST TO TRACK ACROSS NORTHERN IOWA INTO SOUTHERN
WISCONSIN ON TUESDAY AND SHOULD PROVIDE SOME BETTER LIFT TO
DEVELOP A BAND OF PRECIPITATION TO THE NORTHEAST SIDE OF IT. THE
QG FORCING FROM THE MID LEVEL TROUGH APPEARS TO BE SLIGHTLY OFF
TIMING-WISE FROM THE LOW LEVEL FRONTOGENESIS TO WHERE THE
FORCING/MOISTURE IS NOT PARTICULARLY DEEP. THIS IS LIKELY WHY QPF
AMOUNTS ARE NOT MORE THAN A FEW HUNDREDTHS OF AN INCH WITH THIS
SYSTEM. SNOWFALL TOTALS WILL LIKELY BE SOMEWHERE IN THE HALF INCH
TO INCH RANGE WITH THE HIGHER TOTALS MORE LIKELY ACROSS SOUTHEAST
MINNESOTA AND WEST CENTRAL WISCONSIN WHERE THE PRECIPITATION TYPE
WILL REMAIN SNOW THROUGH THE DAY WHILE SOME RAIN COULD MIX IN
ACROSS NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THE DENDRITIC
GROWTH ZONE REMAINS FAIRLY SMALL AT LESS THAN A 100MB THROUGHOUT
THE DAY...SO AM NOT EXPECTING VERY HIGH SNOW TO LIQUID RATIOS FOR
THIS EVENT.
SKIES SHOULD CLEAR OUT TUESDAY NIGHT AS THE FRONT/TROUGH MOVES
THROUGH AND A RIDGE OF HIGH PRESSURE PUSHES IN FROM THE WEST. THIS
WILL SET THE STAGE FOR THE INITIAL STAGES OF A WINTER STORM THAT
WILL LIKELY AFFECT SOME OR ALL OF THE REGION. THE INITIAL BAND OF
PRECIPITATION WILL DEVELOP WEDNESDAY AFTERNOON ACROSS IOWA DUE TO
STRONG LOW LEVEL FRONTOGENETIC FORCING AS THE MAIN MID LEVEL
TROUGH ENTERS THE SOUTHERN PLAINS AND THE SURFACE LOW STARTS TO
DEEPEN IN THE SOUTHERN PLAINS. SOME DIFFERENCES ALREADY START TO
ARISE WEDNESDAY AFTERNOON BETWEEN THE 17.00Z MODEL RUNS WITH THE
ECMWF BEING THE SLOWEST TO BRING THE FRONTOGENETIC BAND INTO IOWA
WHILE THE GFS STRETCHES QPF ALL THE WAY INTO SOUTHWEST MICHIGAN.
THE NAM SHOWS A DRIER SOLUTION THAN WHAT THE GFS IS ADVERTISING
AND IS FURTHER TO THE WEST TO START OUT ON WEDNESDAY AFTERNOON.
WENT MAINLY WITH A 17.00Z GFS/ECMWF BLEND OVER THIS PERIOD AND
KEPT THE PRECIPITATION CHANCES MAINLY IN NORTHEAST IOWA. THE MID
LEVEL TROUGH THEN BEGINS TO CLOSE OFF WEDNESDAY NIGHT WITH THE
SURFACE LOW DEEPENING. THE OVERALL RESULT OF WHAT THE 17.00Z...AND
MANY PREVIOUS RUNS...PRODUCE IS A MAJOR WINTER STORM THAT MOVES
THROUGH THE GREAT LAKES REGION. THE QUESTION AT THIS POINT IS
WHERE THE CORE OF THE TROUGH/SURFACE LOW WILL TRACK.
TO START OUT...THE 17.00Z AND 17.06Z NAM ARE WARM/DEEP OUTLIERS IN
COMPARISON TO THE 17.00Z AND PREVIOUS RUNS OF THE ECMWF/GFS/GEM WITH
TAKING THE SURFACE LOW UP ALONG THE MISSISSIPPI RIVER. THE 17.06Z
RUN DOES APPEAR TO BE TRENDING A LITTLE TO THE EAST...BUT IS STILL
TOO FAR ON THE WEST SIDE OF THE TRACKS TO BE CONSIDERED. WITH MANY
OF THE SREF MEMBERS USING THE NAM...IT ALSO APPEARS TO BE HEAVILY
SKEWED BY IT AND IS TOO FAR WEST AS WELL WITH ITS QPF/LOW TRACK.
THE HIGHEST CONFIDENCE HAS TO BE PLACED WITH THE ECMWF WHICH HAS
BEEN NEARLY IDENTICAL FOR THE PAST 4 RUNS IN REGARD TO TIMING AND
PLACEMENT OF THE SURFACE LOW AND HEAVIEST SNOW BAND. THIS SOLUTION
TAKES THE LOW FROM ST LOUIS TOWARD NORTHERN INDIANA AND DETROIT
WITH THE HEAVIEST SNOW BAND GOING FROM EASTERN IOWA TO SOUTHEAST
WISCONSIN. THE GFS IS NOT TOO FAR OFF FROM THIS SOLUTION...BUT IS
A LITTLE FURTHER WEST OF THIS TRACK AND FASTER WITH THE LOW WHILE
THE GEM IS SOMEWHERE IN BETWEEN THE TWO.
FAVORED THE 17.00Z ECMWF WITH THIS FORECAST...SO WHILE CONFIDENCE
IS RATHER HIGH THAT THIS WINTER STORM WILL OCCUR...THE CONFIDENCE
IS NOT HIGH ENOUGH IN WHERE THE HEAVIEST SNOW BAND WILL END UP TO
ISSUE A LONG LEAD TIME WINTER STORM WATCH. PARTICULARLY SO SINCE
THE ECMWF TAKES THE HIGHER SNOW TOTALS TO THE EAST OF THE FORECAST
AREA. THE COUNTIES THAT ARE MOST LIKELY UNDER THE THREAT OF THE
HEAVIEST SNOWS ARE FROM JUNEAU/ADAMS COUNTIES IN WISCONSIN DOWN TO
CLAYTON COUNTY IN IOWA BASED ON THESE 17.00Z ECMWF/GFS/GEM
RESULTS.
.LONG TERM...THURSDAY THROUGH SUNDAY
329 AM CST MON DEC 17 2012
THE STORM WILL CONTINUE INTO THURSDAY...BUT HOW FAR WEST THE SNOW
LINGERS IS THE MAIN QUESTION. PERHAPS THE BIGGER ISSUE WILL BE
WITH THE STRONG WINDS THAT ACCOMPANY THIS STORM THAT SHOULD LEAD
TO SOME BLOWING SNOW WITH SUSTAINED WINDS REACHING 25 MPH AND
LIKELY GUSTING ABOVE 30 MPH. BY THURSDAY NIGHT...THE STORM WILL
LIKELY HAVE ENDED ACROSS WESTERN WISCONSIN WITH HIGH PRESSURE
PUSHING DOWN FROM SOUTH CENTRAL CANADA. THIS RIDGE WILL REMAIN IN
PLACE THROUGH NEXT WEEKEND AND WILL...ALONG WITH THE FRESH
SNOW PACK...PROVIDE FOR COLD AND DRY CONDITIONS WITH LOWS DROPPING
DOWN INTO THE SINGLE DIGITS.
&&
.AVIATION...THROUGH 06Z TUESDAY
1131 PM CST SUN DEC 16 2012
BIGGEST FORECAST CHALLENGE IS ON CEILINGS HEIGHTS THROUGH THE TAF
PERIOD. SURFACE HIGH OVER SOUTHEASTERN NORTH DAKOTA DRIFTS SOUTH
OVERNIGHT INTO MONDAY. 17.00Z NAM BUFKIT SOUNDING SHOWS MOISTURE
TRAPPED UNDER THE INVERSION...BUT SHALLOWING OUT WITH TIME AND EVEN
SCATTERING OUT BY AFTERNOON. HOWEVER...INFRARED SATELLITE IMAGERY
SHOWING EXTENSIVE LOW STRATUS THROUGHOUT THE
DAKOTAS/MINNESOTA/IOWA AND WISCONSIN...AND 00Z SOUNDING AT ABR
NEAR THE HIGH SHOWS SATURATED LAYER 2700 FEET DEEP. THUS RATHER
PESSIMISTIC THAT THESE LOW CLOUDS WILL SCATTER OUT ANYTIME SOON.
DID KEEP IFR CEILINGS AT KRST THROUGH 23Z THEN LIFTED INTO THE
MVFR CATEGORY. FOR KLSE...EXPECT CEILINGS IN THE UPPER IFR TO
LOWER MVFR CATEGORY THROUGH 15Z...THEN MVFR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
329 AM CST MON DEC 17 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1131 PM CST SUN DEC 16 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
238 PM CST SUN DEC 16 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES AND TYPE FOR
TUESDAY AND WEDNESDAY.
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A POTENT SHORTWAVE TROUGH APPROACHING THE PACIFIC NORTHWEST
AND BROAD TROUGHING ENCOMPASSING MUCH OF THE CENTRAL U.S. INTO THE
WESTERN GREAT LAKES. WITHIN THIS BROAD TROUGHING...THERE ARE VERY
FEW SHORTWAVES THAT LOOK TO HAVE ANY IMPACT ON OUR FORECAST AREA
DURING THE NEXT FEW DAYS. THE ONLY SHORTWAVE REALLY OF NOTE WAS OVER
WESTERN PORTIONS OF MONTANA AND WYOMING. AT THE SURFACE...LOW
PRESSURE WAS OVER UPPER MICHIGAN WHILE HIGH PRESSURE COVERED THE
DAKOTAS INTO WESTERN MINNESOTA. IN-BETWEEN THE TWO...NORTHERLY WINDS
ARE DRIVING COLDER LOW LEVEL AIR INTO THE FORECAST AREA. SURFACE
TEMPERATURES HAVE FALLEN INTO THE 20S OVER PORTIONS OF SOUTHEAST
MINNESOTA WHILE THE REST OF THE AREA REMAINS MOSTLY IN THE 30S. THE
COLD AIR EXTENDS UP TO 850MB WITH 12Z SOUNDINGS FROM BIS...ABR AND
MPX SHOWING -4C TEMPERATURES. ALONG WITH THE COLDER AIR...EXTENSIVE
LOW STRATUS EXISTS FROM THE DAKOTAS INTO THE FORECAST AREA...TRAPPED
BELOW A COLD FRONTAL/SUBSIDENCE INVERSION SHOWN ON THE
AFOREMENTIONED SOUNDINGS. AS THE COLD AIR HAS BEEN FLOWING IN...SOME
FOG HAS DEVELOPED...DUE TO RECENT RAIN AND MELTING SNOW.
VISIBILITIES DROPPED EVEN DOWN TO 1/4SM MILE IN SOME PLACES IN
SOUTHEAST MINNESOTA. LAST ITEM TO NOTE IS A QUICK SNOW DEPTH
COMPARISON TO OBSERVED. THE 16.12Z NAM HAS WAY TOO MUCH SNOW ALONG
AND SOUTH OF I-90...AS ITS SNOW DEPTH INFORMATION HAS NOT UPDATED
SINCE 00Z ON THE 15TH.
TONIGHT AND MONDAY...WEAK UPPER RIDGING WITHIN THE BROAD TROUGH IS
FORECAST TO BUILD INTO THE AREA FOR TONIGHT AND MUCH OF MONDAY...
AHEAD OF THAT SHORTWAVE OVER WESTERN MONTANA AND WYOMING. GOOD MODEL
AGREEMENT EXISTS THAT THE SHORTWAVE WILL REACH WESTERN MINNESOTA BY
00Z TUESDAY. THE WEAK UPPER RIDGING BUILDING IN COMBINED WITH THE
SURFACE RIDGING COMING IN AT THE SURFACE FAVORS DRY CONDITIONS
THROUGH MONDAY. THE BIGGEST QUESTION IS IF THIS STRATUS CAN
DISSIPATE AT ALL. TOUGH TO USE THE NAM...PARTICULARLY ALONG AND
SOUTH OF I-90...SINCE IT HAS TOO MUCH SNOW AND THIS IS INFLUENCING
ITS HANDLING OF BOUNDARY LAYER. HOWEVER...BOTH GFS AND RAP SOUNDINGS
WHICH HAVE A BETTER HANDLE ON THE SNOW DEPTH SITUATION SUGGEST THE
STRATUS WILL DEFINITELY STAY IN PLACE TONIGHT. LOOKS LIKE THERE IS
ENOUGH STIRRING OF THE BOUNDARY LAYER TO PREVENT MORE THAN PATCHY
FOG. PERHAPS THERE IS A SHOT OF DIURNAL MIXING OUT THE STRATUS
TOMORROW...THOUGH MID AND HIGH CLOUDS WILL INCREASE AHEAD OF THE
APPROACHING SHORTWAVE. AS A RESULT...MAINLY CLOUDY CONDITIONS WILL
PREVAIL. THIS MEANS TEMPERATURES FOR THE MOST PART ARE GOING TO BE
INFLUENCED BY ADVECTION. A BLEND OF GUIDANCE SEEMED REASONABLE FOR
BOTH LOWS AND HIGHS.
MONDAY NIGHT AND TUESDAY...THE SHORTWAVE OVER WESTERN MINNESOTA AT
00Z TUESDAY IS SLATED TO CROSS THE AREA MONDAY NIGHT...BUT IT LOOKS
LIKE IT WILL COME THROUGH WITH LITTLE FANFARE OUTSIDE OF SOME
MID/HIGH CLOUDS. THIS IS BECAUSE OF PLENTIFUL DRY AIR IN-BETWEEN
THESE MID/HIGH CLOUDS AND A POSSIBLE HANGING AROUND VERY LOW STRATUS
DECK. OF MORE SIGNIFICANCE IS LATE IN THE NIGHT AND HEADING INTO THE
DAY TUESDAY...WHEN WARM ADVECTION IMPACTS FROM THE POTENT TROUGH
APPROACHING THE PACIFIC NORTHWEST CURRENTLY BEGIN TO MOVE IN. AT 12Z
TUESDAY...MODELS SHOW THE POTENT TROUGH...ALBEIT IN A MUCH WEAKER
STATE AFTER CROSSING THE NORTHERN ROCKIES...STRETCHED FROM THE
DAKOTAS INTO NORTHWEST IOWA. THIS TROUGH SLIDES EAST THROUGH MUCH OF
THE AREA ON TUESDAY...IN RESPONSE TO BUILDING 500MB HEIGHTS
DOWNSTREAM OF DEEP TROUGHING COMING INTO CALIFORNIA. MODELS HAVE
COME INTO GOOD AGREEMENT SHOWING A BAND OF ISENTROPIC LIFT/MID-LEVEL
FRONTOGENESIS ACCOMPANYING THIS TROUGH PASSAGE...YIELDING A BAND OF
QPF LIFTING NORTHWARD THROUGH THE FORECAST AREA DURING THE DAY
TUESDAY. PRECIPITATION COULD DEVELOP AS EARLY AS AFTER MIDNIGHT
MONDAY NIGHT AS SUGGESTED BY THE 16.12Z GFS AND SOME OF THE 16.09Z
SREF ENSEMBLES. HAVE CONFINED A 20 PERCENT CHANCE FOR MONDAY NIGHT
TO SOUTHEAST MINNESOTA. GIVEN THE GOOD AGREEMENT FOR TUESDAY...
INCREASED CHANCES UP TOWARDS 50...HIGHEST NORTH OF I-90 WHERE THE
BEST CONSENSUS EXISTS. HIGHER CHANCES MAY BE NECESSARY IN FUTURE
FORECASTS. AMOUNTS DO NOT LOOK LIKE A WHOLE LOT...BETWEEN THE BAND
LIFTING NORTH AND LIFT THAT IS QUALITATIVELY MODERATE AT BEST.
PRECIPITATION TYPE COULD BE AN ISSUE...WITH THE 16.12Z NAM SHOWING A
WARM NOSE AROUND 2C AROUND 2000 FT AGL ACCOMPANYING THE BAND. THE
GFS SUGGESTS ALL SNOW AND WILL PLAY THAT ROUTE FOR NOW AS IT SEEMS
THAT THE WARM NOSE SHOULD ACTUALLY COME IN SOUTH OF THE BAND. AFTER
THE PASSAGE OF THE BAND...THE GFS AND NAM SHOWS SKIES CLEARING OUT.
THIS MAY OCCUR AND IF IT DOES...TEMPERATURES SOUTH OF I-90 COULD POP
INTO THE 40S. FOR NOW TAKING A CONSENSUS APPROACH AS THE ECMWF
SUGGESTS A SLOWER LIFT NORTH OF THE BAND.
TUESDAY NIGHT AND WEDNESDAY...ATTENTION BEGINS TO SHIFT TO THE
TROUGHING OVER CALIFORNIA AT 00Z WEDNESDAY. GOOD MODEL AGREEMENT
EXISTS OF IT SLIDING ACROSS ARIZONA AND NEW MEXICO DURING THIS
PERIOD...RESULTING IN DEEPENING LOW PRESSURE ACROSS THE OKLAHOMA AND
TEXAS PANHANDLES. DOWNSTREAM...500MB HEIGHTS CONTINUE TO RISE...
PARTICULARLY ACROSS THE LOWER AND MID-MISSISSIPPI RIVER VALLEY. THIS
IN TURN SETS UP A STRENGTHENING MID-LEVEL FRONTOGENESIS ZONE
INITIALLY ACROSS COLORADO...THEN SPREADING UP THROUGH KANSAS...
EASTERN NEBRASKA AND EVENTUALLY IOWA BY WEDNESDAY AFTERNOON. THE
16.12Z NAM APPEARS TO BE AN OUTLIER IN EJECTING THE SURFACE SYSTEM
NORTH TO KANSAS CITY BY 00Z THURSDAY...COMPARED TO THE
GFS/ECMWF/UKMET/CANADIAN WHICH ALL HOLD IT BACK OVER OKLAHOMA. THE
FASTER EJECTING NAM WOULD ALLOW WARMER AIR TO ENTER SOUTHERN
SECTIONS OF THE FORECAST AREA ON WEDNESDAY AS WELL AS PRECIP INTO
SOUTH CENTRAL MINNESOTA. THE LATTER MORE FAVORED GROUP REQUIRES
HAVING SOME CHANCES OF PRECIPITATION...SNOW OR RAIN/SNOW MIX...TO
SOUTHERN SECTIONS OF THE FORECAST AREA WEDNESDAY AFTERNOON.
OTHERWISE...THE REST OF THE PERIOD IS DRY. WEAK PRESSURE GRADIENT
AFTER MIDNIGHT TUESDAY NIGHT PLUS POSSIBLE CLEARING WOULD
RESULT IN GOOD RADIATIONAL COOLING CONDITIONS...THOUGH THE EXTENT OF
CLEARING IS UNCERTAIN AT THIS TIME. PLUS...MID/HIGH CLOUDS MAY
ALREADY BE APPROACHING THE AREA ASSOCIATED WITH THE FRONTOGENESIS
TUESDAY NIGHT...THICKENING OVER THE AREA ON WEDNESDAY. THUS HAVE
STAYED TOWARD A GUIDANCE BLEND FOR BOTH HIGHS AND LOWS.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
238 PM CST SUN DEC 16 2012
FOCUS CONTINUES TO BE ON THE DEEP TROUGHING COMING OUT OF NEW MEXICO
AND THE ASSOCIATED SURFACE SYSTEM IN OKLAHOMA.
ECMWF/CANADIAN/GFS/UKMET AND GFS ENSEMBLES ALL STILL SUGGEST PHASING
OF THIS TROUGHING AND A NORTHERN STREAM TROUGH DROPPING DOWN INTO
THE NORTHERN PLAINS. HOWEVER...TRENDS OF THE ABOVE MODELS ARE ALL
SHOWING THIS PHASING TAKING PLACE FARTHER EAST WITH THE TRACKS NOW
MAINLY GOING UP THROUGH INDIANA. THIS TREND IS GETTING CONCERNING
FOR PRECIPITATION FOR WEDNESDAY NIGHT AND THURSDAY...ESPECIALLY
OVER THE NORTHWEST 1/3 OR SO WHERE IT COULD END UP DRY. CERTAINLY
PLENTY OF TIME FOR ADJUSTMENTS FOR THE TRACK GIVEN THAT THE DEEP
TROUGH PORTION IS STILL SOUTH OF THE ALEUTIANS. ADJUSTED THE
PRECIPITATION CHANCES SLIGHTLY DOWNWARD FOR WEDNESDAY NIGHT AND
THURSDAY TO ACCOUNT FOR THE SOUTHEAST TREND...BUT AT LEAST AT THIS
TIME THE SOUTHEAST HALF OF THE FORECAST AREA STILL LOOKS GOOD TO
PICK UP SOME ACCUMULATING SNOW.
AFTER THE WEDNESDAY NIGHTTHURSDAY SYSTEM...THE PATTERN LOOKS QUIET
WITH UPPER RIDGING DOMINATING THE WESTERN HALF OF THE U.S. OR SO AND
THE FORECAST AREA IN WEST TO NORTHWEST FLOW AND HIGH PRESSURE AT THE
SURFACE. CERTAINLY SOME COLDER AIR WILL COME DOWN IN THE WAKE OF THE
SYSTEM...SENDING TEMPERATURES DOWN TO NEAR OR JUST BELOW NORMAL...
BUT IT APPEARS THIS WILL BE SHORT-LIVED AS 500MB HEIGHTS RISE.
&&
.AVIATION...THROUGH 06Z TUESDAY
1131 PM CST SUN DEC 16 2012
BIGGEST FORECAST CHALLENGE IS ON CEILINGS HEIGHTS THROUGH THE TAF
PERIOD. SURFACE HIGH OVER SOUTHEASTERN NORTH DAKOTA DRIFTS SOUTH
OVERNIGHT INTO MONDAY. 17.00Z NAM BUFKIT SOUNDING SHOWS MOISTURE
TRAPPED UNDER THE INVERSION...BUT SHALLOWING OUT WITH TIME AND EVEN
SCATTERING OUT BY AFTERNOON. HOWEVER...INFRARED SATELLITE IMAGERY
SHOWING EXTENSIVE LOW STRATUS THROUGHOUT THE
DAKOTAS/MINNESOTA/IOWA AND WISCONSIN...AND 00Z SOUNDING AT ABR
NEAR THE HIGH SHOWS SATURATED LAYER 2700 FEET DEEP. THUS RATHER
PESSIMISTIC THAT THESE LOW CLOUDS WILL SCATTER OUT ANYTIME SOON.
DID KEEP IFR CEILINGS AT KRST THROUGH 23Z THEN LIFTED INTO THE
MVFR CATEGORY. FOR KLSE...EXPECT CEILINGS IN THE UPPER IFR TO
LOWER MVFR CATEGORY THROUGH 15Z...THEN MVFR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
238 PM CST SUN DEC 16 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
134 AM MST WED DEC 19 2012
.UPDATE...
ISSUED AT 134 AM MST WED DEC 19 2012
AFTER A SLOW START LAST EVENING...SNOW WAS QUICKLY ACCUMULATING ALONG THE
I-70 CORRIDOR EARLY THIS MORNING PER CDOT WEB CAMS. THIS WAS UNDER
THE 700 MB FRONTAL ZONE...WHICH CURVED DOWN INTO SCENTRAL UT AND HAS
BROUGHT SNOW TO MOAB. CLOUD TOPS WERE COOLING ACROSS SE UT SO EXPECT
PRECIP TO EXPAND THERE...HERE IT MAY INITIALLY BE RAIN/SNOW MIX.
NAM12 AND RAP40 MODELS INDICATE BEST FORCING STILL TO COME...PEAKING
TOWARD 12Z AS THE 700 MB LOW TRACKS ACROSS WEST-CENTRAL CO AND A
DEVELOPING SURFACE LOW MOVES EAST ACROSS SE UT/SW CO. THE COLD
FRONT IS EXPECTED TO REACH THE CORTEZ AREA AROUND 12Z /5 AM MST/
AND SHOULD SEE INCREASE IN INTENSITY ACROSS SW CO AS THE FRONT NEARS.
SNOW CEASED AT VERNAL PRIOR TO MIDNIGHT...BUT COULD SEE IT PICK UP
AGAIN AS THE 700 MB LOW PASSES TO ITS SOUTH. SNOW CONTINUED ACROSS
NW CO PER CRAIG AND MEEKER ASOS OBSERVATIONS. CURRENT FORECAST AND
WINTER HIGHLIGHTS APPEAR ON TRACK.
UPDATE ISSUED AT 953 PM MST TUE DEC 18 2012
ADDED WINTER WEATHER ADVISORY FOR EXTREME SOUTHEAST UTAH...
PRIMARILY NORTH OF HIGHWAY 163. EXPECT RAIN INITIALLY...BUT SHOULD
TURN OVER TO SNOW PRETTY QUICKLY. WITH LOW PASSING JUST SOUTH OF
THE AREA...EXPECT THERE WILL BE A PERIOD OF HEAVY SNOW YIELDING
FROM 2 TO 4 INCHES BY MID MORNING.
UPDATE ISSUED AT 547 PM MST TUE DEC 18 2012
UPGRADED THE WINTER WEATHER ADVISORY IN THE EASTERN UINTA BASIN
TO A WINTER STORM WARNING. SPOTTERS HAVE REPORTED FROM 4 TO 7
INCHES ALREADY ON THE GROUND. SNOW WILL CONTINUE THIS EVENING
BEFORE TAPERING OFF LATER TONIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 218 PM MST TUE DEC 18 2012
THIS LATE AFTERNOON THE FORECAST AREA IS DIVIDED INTO TWO REGIMES
DIVIDED BY THE COLD FRONT LAYING ALONG THE ROAN-TAVAPUTS PLATEAU
INTO THE FLATTOPS. ALONG AND NORTH OF THE FRONT...HEAVY SNOW HAS
BEEN FALLING. STATE PATROL REPORTS AROUND 6 INCHES IN CRAIG THOUGH
ONLY HALF AND INCH IN VERNAL. CROSHO AND BUFFALO PARK SNOTELS REPORT 15
INCHES OF NEW SNOW. SOUTH OF THE FRONT SNOWFALL HAS BEEN MUCH MORE
SKETCHY...MAINLY ALONG SW FACING SLOPES.
A STRONG WEST TO EAST ORIENTED JET STREAK ALONG THE WYOMING
BORDER THIS MORNING HAS LIFTED OFF TO THE NE TODAY. IN RESPONSE
THE MID-UPPER FLOW HAS BACKED TO SSW TODAY PRODUCING WARM
ADVECTION. THIS WARM OVER-RUNNING HAS HELPED TO PRODUCE THE HEAVY
SNOWFALL ALONG THE STATIONARY FRONT. SOUTH OF THE
FRONT...AFTERNOON SURFACE TEMPERATURES CLIMBED SEVERAL DEGREES
ABOVE GUIDANCE. STRONG ISENTROPIC UPGLIDE WILL CONTINUE INTO THIS
EVENING. THIS STABILIZING PATTERN CAN BE SEEN ON RADAR WITH MTN
WAVE BANDING SEEN TO THE NORTH OF THE RADAR TRANSMITTER.
WET BULB ZERO AND 700MB TEMPS SUPPORT SNOW DOWN TO 4500FT SO ANY
SHOWERS WILL QUICKLY TURN TO SNOW.
THE UPPER LEVEL TROUGH MOTION...THROUGH THE GREAT BASIN TONIGHT...
HAS GOOD MODEL CONTINUITY. YET THE 18Z NAM AND RAP BOTH SUPPORT A
LATER FRONTAL ADVANCE HOWEVER...NOW INTO THE I-70 CORRIDOR AROUND
MIDNIGHT TONIGHT. THIS PUTS THE CENTRAL VALLEY WARNINGS IN DOUBT
BUT DOES NOT REMOVE THE POTENTIAL TO GET UP TO 6 INCHES OF
SNOWFALL THERE. BASED ON THIS AND IN COORDINATION WITH THE SLC
OFFICE... HAVE KEPT THE WARNINGS IN PLACE AND SLOWED THE WORDING
TO EMPHASIZE THE PERIOD BETWEEN MIGHT AND SUNRISE.
THE SOUTHERN ZONES TOO WILL SEE IMPRESSIVE FRONTAL FORCING AFTER
MIDNIGHT INTO WEDNESDAY MORNING. IN THE COLD SECTOR OF THE STORM
LATE TONIGHT THROUGH WEDNESDAY...700MB TEMPERATURES WILL DROP
RIGHT THROUGH THE DENDRITIC CRYSTAL GROWTH REGIME TO -17C BY
WEDNESDAY AFTERNOON. THIS WILL VERY EFFICIENTLY EEK OUT ALL
AVAILABLE MOISTURE. ONLY NW-FACING SLOPES WILL CONTINUE THROUGH
WEDNESDAY AFTERNOON WITH ALL SHOWERS SHUTTING DOWN BY SUNSET. A
VERY COLD NIGHT IS IN STORE FOR WEDNESDAY NIGHT.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 430 AM
MST TUE DEC 18 2012
DRIER NORTHWESTERLY FLOW ALOFT OVERHEAD WEDNESDAY NIGHT AS THE STORM
SYSTEM CONTINUES TO MOVE EAST. A RIDGE OF HIGH PRESSURE WILL MOVE
EAST OVER THE REGION AND REMAIN DOMINATE DURING THE END OF THE WEEK.
WITH SNOW ON THE GROUND...THE COLD AIR MASS BEHIND THE FRONT AND HIGH
PRESSURE EXPECT VALLEY INVERSIONS. TEMPERATURES SHOULD REMAIN COLD
IN THE VALLEYS. THEREFORE WENT BELOW GUIDANCE FOR THESE LOCATIONS.
THE COLDEST MORNING SHOULD BE THURSDAY WHICH SHOULD ALSO BE THE
COLDEST OF THE SEASON. BY THE END OF THE WEEK TEMPERATURES SHOULD BE
MODIFIED SLIGHTLY BUT THIS WILL BE A SLOW PROCESS DUE TO THE
PREVIOUSLY MENTIONED RIDGE OF HIGH PRESSURE.
THE RIDGE WILL SLIDE EASTWARD ALLOWING THE NEXT STORM SYSTEM INTO
THE AREA BY MONDAY ALTHOUGH THE TIMING AND PLACEMENT VARIES BETWEEN
MODELS. INCREASED THE PRECIPITATION FORECAST SLIGHTLY TO HIGHLIGHT
THAT A STORM IS ON THE HORIZON. THAT SAID THERE ARE MANY VARIABLES
STILL NOT WORKED OUT YET SO MUCH UNCERTAINTY WITH TIMING AND
STRENGTH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 953 PM MST TUE DEC 18 2012
WIDESPREAD MODERATE TO STRONG MECHANICAL TURBULENCE EXPECTED THIS
EVENING ALONG AND NORTH OF AREA RIDGES AND MTNS ACROSS SOUTHEAST
UTAH AND SOUTHWEST COLORADO LATE TONIGHT. WRN COLORADO TAF SITES
...DETERIORATING CONDITIONS TONIGHT WITH LOWERING CIGS BECOMING
WIDESPREAD IFR FOR ALL TAF SITES. WIDESPREAD 1 1/2SM -SN BR CIGS
VV002 IS EXPECTED INTO WEDNESDAY MORNING. AREAS OF MODERATE SN
FOR ALL AREAS OVERNIGHT THROUGH WEDNESDAY MORNING. SHOWERS BECOME
SCATTERED OVER THE DIVIDE MOUNTAINS WEDNESDAY AFTERNOON BEFORE
DIMINISHING IN THE EVENING.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING UNTIL NOON MST TODAY FOR COZ003-006>008-011-
014-020-022-023.
WINTER STORM WARNING UNTIL 6 AM MST EARLY THIS MORNING FOR
COZ001-002.
WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR COZ004-005-
009-010-012-013-017>019.
WINTER WEATHER ADVISORY UNTIL NOON MST TODAY FOR COZ021.
UT...WINTER STORM WARNING UNTIL NOON MST TODAY FOR UTZ025.
WINTER STORM WARNING UNTIL 6 AM MST EARLY THIS MORNING FOR
UTZ023-024.
WINTER STORM WARNING UNTIL 8 AM MST THIS MORNING FOR UTZ027.
WINTER WEATHER ADVISORY UNTIL 8 AM MST THIS MORNING FOR UTZ022-
029.
WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR UTZ028.
&&
$$
UPDATE...JAD
SHORT TERM...JOE
LONG TERM...AS
AVIATION...TGJT
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
953 PM MST TUE DEC 18 2012
.UPDATE...
ISSUED AT 953 PM MST TUE DEC 18 2012
ADDED WINTER WEATHER ADVISORY FOR EXTREME SOUTHEAST UTAH...
PRIMARILY NORTH OF HIGHWAY 163. EXPECT RAIN INITIALLY...BUT SHOULD
TURN OVER TO SNOW PRETTY QUICKLY. WITH LOW PASSING JUST SOUTH OF
THE AREA...EXPECT THERE WILL BE A PERIOD OF HEAVY SNOW YIELDING
FROM 2 TO 4 INCHES BY MID MORNING.
UPDATE ISSUED AT 547 PM MST TUE DEC 18 2012
UPGRADED THE WINTER WEATHER ADVISORY IN THE EASTERN UINTA BASIN
TO A WINTER STORM WARNING. SPOTTERS HAVE REPORTED FROM 4 TO 7
INCHES ALREADY ON THE GROUND. SNOW WILL CONTINUE THIS EVENING
BEFORE TAPERING OFF LATER TONIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 218 PM MST TUE DEC 18 2012
THIS LATE AFTERNOON THE FORECAST AREA IS DIVIDED INTO TWO REGIMES
DIVIDED BY THE COLD FRONT LAYING ALONG THE ROAN-TAVAPUTS PLATEAU
INTO THE FLATTOPS. ALONG AND NORTH OF THE FRONT...HEAVY SNOW HAS
BEEN FALLING. STATE PATROL REPORTS AROUND 6 INCHES IN CRAIG THOUGH
ONLY HALF AND INCH IN VERNAL. CROSHO AND BUFFALO PARK SNOTELS REPORT 15
INCHES OF NEW SNOW. SOUTH OF THE FRONT SNOWFALL HAS BEEN MUCH MORE
SKETCHY...MAINLY ALONG SW FACING SLOPES.
A STRONG WEST TO EAST ORIENTED JET STREAK ALONG THE WYOMING
BORDER THIS MORNING HAS LIFTED OFF TO THE NE TODAY. IN RESPONSE
THE MID-UPPER FLOW HAS BACKED TO SSW TODAY PRODUCING WARM
ADVECTION. THIS WARM OVER-RUNNING HAS HELPED TO PRODUCE THE HEAVY
SNOWFALL ALONG THE STATIONARY FRONT. SOUTH OF THE
FRONT...AFTERNOON SURFACE TEMPERATURES CLIMBED SEVERAL DEGREES
ABOVE GUIDANCE. STRONG ISENTROPIC UPGLIDE WILL CONTINUE INTO THIS
EVENING. THIS STABILIZING PATTERN CAN BE SEEN ON RADAR WITH MTN
WAVE BANDING SEEN TO THE NORTH OF THE RADAR TRANSMITTER.
WET BULB ZERO AND 700MB TEMPS SUPPORT SNOW DOWN TO 4500FT SO ANY
SHOWERS WILL QUICKLY TURN TO SNOW.
THE UPPER LEVEL TROUGH MOTION...THROUGH THE GREAT BASIN TONIGHT...
HAS GOOD MODEL CONTINUITY. YET THE 18Z NAM AND RAP BOTH SUPPORT A
LATER FRONTAL ADVANCE HOWEVER...NOW INTO THE I-70 CORRIDOR AROUND
MIDNIGHT TONIGHT. THIS PUTS THE CENTRAL VALLEY WARNINGS IN DOUBT
BUT DOES NOT REMOVE THE POTENTIAL TO GET UP TO 6 INCHES OF
SNOWFALL THERE. BASED ON THIS AND IN COORDINATION WITH THE SLC
OFFICE... HAVE KEPT THE WARNINGS IN PLACE AND SLOWED THE WORDING
TO EMPHASIZE THE PERIOD BETWEEN MIGHT AND SUNRISE.
THE SOUTHERN ZONES TOO WILL SEE IMPRESSIVE FRONTAL FORCING AFTER
MIDNIGHT INTO WEDNESDAY MORNING. IN THE COLD SECTOR OF THE STORM
LATE TONIGHT THROUGH WEDNESDAY...700MB TEMPERATURES WILL DROP
RIGHT THROUGH THE DENDRITIC CRYSTAL GROWTH REGIME TO -17C BY
WEDNESDAY AFTERNOON. THIS WILL VERY EFFICIENTLY EEK OUT ALL
AVAILABLE MOISTURE. ONLY NW-FACING SLOPES WILL CONTINUE THROUGH
WEDNESDAY AFTERNOON WITH ALL SHOWERS SHUTTING DOWN BY SUNSET. A
VERY COLD NIGHT IS IN STORE FOR WEDNESDAY NIGHT.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 430 AM
MST TUE DEC 18 2012
DRIER NORTHWESTERLY FLOW ALOFT OVERHEAD WEDNESDAY NIGHT AS THE STORM
SYSTEM CONTINUES TO MOVE EAST. A RIDGE OF HIGH PRESSURE WILL MOVE
EAST OVER THE REGION AND REMAIN DOMINATE DURING THE END OF THE WEEK.
WITH SNOW ON THE GROUND...THE COLD AIR MASS BEHIND THE FRONT AND HIGH
PRESSURE EXPECT VALLEY INVERSIONS. TEMPERATURES SHOULD REMAIN COLD
IN THE VALLEYS. THEREFORE WENT BELOW GUIDANCE FOR THESE LOCATIONS.
THE COLDEST MORNING SHOULD BE THURSDAY WHICH SHOULD ALSO BE THE
COLDEST OF THE SEASON. BY THE END OF THE WEEK TEMPERATURES SHOULD BE
MODIFIED SLIGHTLY BUT THIS WILL BE A SLOW PROCESS DUE TO THE
PREVIOUSLY MENTIONED RIDGE OF HIGH PRESSURE.
THE RIDGE WILL SLIDE EASTWARD ALLOWING THE NEXT STORM SYSTEM INTO
THE AREA BY MONDAY ALTHOUGH THE TIMING AND PLACEMENT VARIES BETWEEN
MODELS. INCREASED THE PRECIPITATION FORECAST SLIGHTLY TO HIGHLIGHT
THAT A STORM IS ON THE HORIZON. THAT SAID THERE ARE MANY VARIABLES
STILL NOT WORKED OUT YET SO MUCH UNCERTAINTY WITH TIMING AND
STRENGTH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 953 PM MST TUE DEC 18 2012
WIDESPREAD MODERATE TO STRONG MECHANICAL TURBULENCE EXPECTED THIS
EVENING ALONG AND NORTH OF AREA RIDGES AND MTNS ACROSS SOUTHEAST
UTAH AND SOUTHWEST COLORADO LATE TONIGHT. WRN COLORADO TAF SITES
...DETERIORATING CONDITIONS TONIGHT WITH LOWERING CIGS BECOMING
WIDESPREAD IFR FOR ALL TAF SITES. WIDESPREAD 1 1/2SM -SN BR CIGS
VV002 IS EXPECTED INTO WEDNESDAY MORNING. AREAS OF MODERATE SN
FOR ALL AREAS OVERNIGHT THROUGH WEDNESDAY MORNING. SHOWERS BECOME
SCATTERED OVER THE DIVIDE MOUNTAINS WEDNESDAY AFTERNOON BEFORE
DIMINISHING IN THE EVENING.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING UNTIL NOON MST WEDNESDAY FOR COZ003-006>008-
011-014-020-022-023.
WINTER STORM WARNING UNTIL 6 AM MST WEDNESDAY FOR COZ001-002.
WINTER STORM WARNING UNTIL 6 PM MST WEDNESDAY FOR COZ004-005-009-
010-012-013-017>019.
WINTER WEATHER ADVISORY UNTIL NOON MST WEDNESDAY FOR COZ021.
UT...WINTER STORM WARNING UNTIL NOON MST WEDNESDAY FOR UTZ025.
WINTER STORM WARNING UNTIL 6 AM MST WEDNESDAY FOR UTZ023-024.
WINTER STORM WARNING UNTIL 8 AM MST WEDNESDAY FOR UTZ027.
WINTER WEATHER ADVISORY UNTIL 8 AM MST WEDNESDAY FOR UTZ022-029.
WINTER STORM WARNING UNTIL 6 PM MST WEDNESDAY FOR UTZ028.
&&
$$
UPDATE...NL
SHORT TERM...JOE
LONG TERM...AS
AVIATION...TGJT
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
420 AM EST WED DEC 19 2012
.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN
UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 420 AM EST WED DEC 19 2012
A VERY POTENT LOW PRESSURE SYSTEM WILL DEVELOP OVER THE PANHANDLE
REGION TODAY...AND QUICKLY INTENSIFY AS IT HOOKS INTO THE GREAT
LAKES OVER THE NEXT 48 HOURS. THIS SYSTEM WILL BRING WIDESPREAD
RAINFALL BEGINNING TONIGHT AND CONTINUING INTO THURSDAY...WITH
PRECIPITATION CHANGING TO ALL SNOW NEAR TO SHORTLY AFTER SUNSET
THURSDAY EVENING. LIGHT ACCUMULATIONS APPEAR POSSIBLE THURSDAY
NIGHT INTO EARLY FRIDAY. BROAD COLD HIGH PRESSURE WILL CONTROL THE
AREA THROUGH THE WEEKEND...WITH PRECIPITATION CHANCES RETURNING
EARLY NEXT WEEK AS LARGE SCALE TROUGHING DEVELOPS ACROSS MUCH OF
THE COUNTRY.
&&
.NEAR TERM /TODAY/...
ISSUED AT 420 AM EST WED DEC 19 2012
FOCUS IS ON TEMPS AND SKY COVER. GUIDANCE IS SIMILAR AND A BLEND
IS SUFFICIENT.
EXPANSIVE STRATUS DECK CURRENTLY OVER THE NORTHERN HALF OF THE
AREA. EXPECT THAT THIS WILL CONTINUE THROUGH MID MORNING AND BEGIN
TO BREAK UP...HOWEVER MID AND HIGH CLOUD WILL REPLACE IT. MAIN
IMPACT OF THIS WILL BE TO LIMIT WARMING ACROSS THE NORTH...AND
HAVE UNDERCUT GUIDANCE TEMPS AS A RESULT ACROSS THE NORTHERN HALF.
CONSENSUS NUMBERS APPEARED FINE ELSEWHERE...WHERE SUNSHINE SHOULD
BE AMPLE THROUGH MIDDAY.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 420 AM EST WED DEC 19 2012
FOCUS IS ON POTENT STORM SYSTEM MOVING THROUGH THE AREA TONIGHT
THROUGH EARLY FRIDAY. GUIDANCE IS IN SURPRISINGLY GOOD AGREEMENT
FOR SUCH A STRONG AND RAPIDLY DEVELOPING SYSTEM.
EXPECT THAT PRECIPITATION WILL MOVE INTO THE AREA BY LATE IN THE
EVENING...OVERSPREADING THE ENTIRE AREA LATE TONIGHT. GIVEN
DYNAMIC NATURE OF THE SYSTEM...HAVE CONTINUED TO MAINTAIN THE
CHANCE THUNDER MENTION LATE TONIGHT INTO EARLY THURSDAY. SREF
PROBABILITIES ARE SUPPORTIVE OF THIS AS WELL. COLD FRONT SHOULD BE
BLASTING THROUGH THE REGION THURSDAY AFTERNOON...AND APPEARS
LIKELY THAT AT LEAST A BRIEF BREAK IN PRECIPITATION ASSOCIATED
WITH DRY SLOT WILL OCCUR...FOLLOWED BY WRAP AROUND PRECIP LATE
THURSDAY AFTERNOON INTO THURSDAY NIGHT. CHANGEOVER TO SNOW SHOULD
BE OCCURRING IN PORTIONS OF THE WESTERN THIRD TO HALF OF THE AREA
BY LATE THURSDAY AFTERNOON...AND ALL PRECIP SHOULD BE SNOW AFTER
00Z FRIDAY. MODELS HAVE SLOWED DOWN THE SYSTEM A BIT AND THUS THE
DEPARTURE OF THE DEEPER MOISTURE. PER FORECAST SOUNDINGS...SNOW
SHOWERS MAY CONTINUE INTO FRIDAY MORNING AS DENDRITIC ZONE REMAINS
SATURATED...AND FLURRIES OFF THE LAKE MAY BE POSSIBLE INTO FRIDAY
AFTERNOON IN THE NORTHEAST.
LIGHT ACCUMULATIONS LOOK TO BE A GOOD BET...ESPECIALLY ACROSS THE
NORTHERN HALF OR SO OF THE FORECAST AREA. AT THIS TIME...BEST
ESTIMATE IS AROUND AN INCH ALONG THE INTERSTATE 70 CORRIDOR...WITH
1 TO 3 NORTH AND LESS THAN AN INCH SOUTH. BEING THE FIRST
SIGNIFICANT ACCUMULATING SNOWFALL OF THE SEASON...WILL HIGHLIGHT
THIS STRONGLY IN AN SPS AND IN THE HWO. HEADLINES MAY BECOME
NECESSARY SOON BUT WILL PUNT ON THIS FOR NOW AS IT IS STILL 4-5
PERIODS OUT.
ANOTHER MAJOR ISSUE OF CONCERN WILL BE WINDS. SUSTAINED
WINDS...ESPECIALLY IN THE WAKE OF THE COLD FRONT THURSDAY
AFTERNOON INTO FRIDAY...ARE LIKELY TO REACH 25-30 MPH...WITH GUSTS
OF 40-45 MPH. COMBINED WITH LIGHT SNOWFALL ACCUMULATIONS THIS MAY
CAUSE SOME DIFFICULT TRAVEL DURING THIS TIME PERIOD...AND BEYOND
THE SNOWFALL WILL LEAD TO VERY COLD AND RAW CONDITIONS...LIKELY
THE COLDEST OF THE SEASON SO FAR...WITH WIND CHILLS DOWN INTO THE
SINGLE DIGITS THURSDAY NIGHT AND FRIDAY. WILL ALSO HIGHLIGHT THIS
IN SPS/HWO.
ON TEMPS...RAISED GUIDANCE TONIGHT INTO EARLY THURSDAY WITH STRONG
WARM ADVECTION ONGOING...AND LOWERED GUIDANCE BEYOND WITH STRONG
COLD ADVECTION OCCURRING AND FRESH SNOWFALL LIKELY TO HELP
SUPPRESS TEMPS...ESPECIALLY AT NIGHT. NON DIURNAL TEMP CURVES
EXPECTED LATE TONIGHT INTO THURSDAY...WITH TONIGHTS LOWS LIKELY
TO BE REACHED THIS EVENING AND HIGHS THURSDAY LIKELY REACHED
THURSDAY LATE MORNING OR MIDDAY.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 338 AM EST WED DEC 19 2012
COLD DRY WEATHER FOR THE WEEKEND FOLLOWED BY AN INCREASINGLY
COMPLEX AND ACTIVE WEATHER REGIME FOR THE FIRST HALF OF NEXT
WEEK...WITH THE POSSIBILITY OF A MAJOR STORM IMPACTING THE REGION
NEAR THE TAIL END OR JUST BEYOND THE EXTENDED PERIOD.
POLAR VORTEX ASSOCIATED WITH THE DEEP LOW PRESSURE THAT WILL
IMPACT THE REGION THURSDAY/FRIDAY WILL SETTLE ACROSS NEW ENGLAND
OVER THE WEEKEND. THE BLOCKY AMPLIFIED FLOW PATTERN ALOFT ACROSS
THE COUNTRY AND INTO THE NORTH ATLANTIC HOWEVER WILL ALLOW THE
UPPER LOW TO MOVE ONLY SLOWLY INTO THE CANADIAN MARITIMES THROUGH
SUNDAY. THIS WILL KEEP THE MIDWEST AND GREAT LAKES IN A NORTHWEST
FLOW ALOFT THROUGH THE WEEKEND WITH HIGH PRESSURE AT THE
SURFACE...RESULTING IN COLD DRY WEATHER FOR CENTRAL INDIANA. HIGHS
WILL LARGELY REMAIN IN THE 30S THIS WEEKEND WITH LOWS IN THE 20S.
SHARP UPPER LEVEL TROUGH OFF THE WEST COAST THIS WEEKEND WILL
SHIFT EAST INTO THE CENTRAL PART OF THE COUNTRY BY TUESDAY...
SETTING THE FRAMEWORK FOR A RESUMPTION OF AN ACTIVE WEATHER
PATTERN FOR MUCH OF THE EASTERN U S BY THE MIDDLE OF NEXT WEEK.
AT LEAST INITIALLY ON MONDAY...THE ECMWF/OP GFS/GGEM ALL DEVELOP A
SURFACE WAVE ACROSS THE MISSISSIPPI VALLEY MOVING INTO THE
EASTERN U S BY TUESDAY. OP GFS AND GGEM BOTH DEEPEN THIS LOW
MORESO THAN THE ECMWF WHICH MAINTAINS A FLATTER FLOW ALOFT AND
KEEPS A WARM FRONT DRAPED TO THE SOUTH OF THE REGION AS THE
AFOREMENTIONED UPPER TROUGH BEGINS TO AMPLIFY OVER THE ROCKIES.
PRESENCE OF THE WAVE WITH INCREASING ISENTROPIC LIFT OVER THE
BOUNDARY WARRANTS A LOW CHANCE POPS MONDAY AND MONDAY NIGHT. WITH
COOL EASTERLY FLOW NORTH OF THE BOUNDARY...WILL CARRY A RAIN/SNOW
MIX.
EXPECT MOISTURE WILL CONTINUE TO INCREASE ON TUESDAY WITH SOUTHWEST
FLOW ALOFT AHEAD OF THE AMPLIFYING UPPER TROUGH ON TUESDAY AND
WILL CARRY CHANCE POPS THROUGH CHRISTMAS. ECMWF AND OP GFS
CONTINUE TO ADVERTISE RAPID CYCLOGENESIS TUESDAY NIGHT INTO
WEDNESDAY OVER THE EASTERN U S BUT AS WOULD BE EXPECTED AT 7-8
DAYS OUT CONTINUE TO DIFFER FROM RUN TO RUN AND WITH EACH OTHER
WITH RESPECT TO SYSTEM TRACK AND TIMING OF IMPACTS. PROVIDING ANY
ADDITIONAL DETAILS IS DIFFICULT AT THIS POINT IN TIME...BUT
NEEDLESS TO SAY WILL CONTINUE TO MONITOR MODEL TRENDS AND PATTERN
EVOLUTION OVER THE NEXT SEVERAL DAYS.
&&
.AVIATION /DISCUSSION FOR THE 190900Z TAF UPDATE/...
ISSUED AT 338 AM EST WED DEC 19 2012
WIND GUSTS EXPERIENCED EARLIER THIS MORNING HAVE DROPPED OFF
SIGNIFICANTLY WITH WINDS BACK TO A 10-15KT RANGE. RAP MODEL
SOUNDINGS AND 950/925MB RH PROGS INDICATE MVFR CEILINGS LIKELY TO
LINGER THROUGH DAYBREAK BEFORE WEAK RIDGING ALLOWS FOR DRYING
INTO THE LOWER LEVELS WITH STRATUS SCATTERING BY LATE MORNING.
WILL ALSO BE REMOVING ANY MENTION OF LOW LEVEL WIND SHEAR AS
925MB JETLET HAS SHIFTED EAST OF THE REGION.
06Z DISCUSSION FOLLOWS.
MVFR CONDITIONS EXPECTED OVERNIGHT...WITH LLWS POSSIBLE. A
RETURN TO VFR IS EXPECTED AFTER 15Z WED.
QUICK MOVING SHORT WAVE AND ASSOCIATED AREA OF LOW PRESSURE WERE
OVER NORTHERN INDIANA AND QUICKLY MOVING EAST. GUSTY WINDS WERE
FOUND IN THE WAKE OF THE SYSTEM. GFS AND NAM SUGGEST A WIND FIELD
OF 40-50 KNTS AT 925MB. THUS HAVE INCLUDED SOME LLWS MENTIONED FOR
SPEED DIFFERENCES. MVFR CIGS OBSERVED IN THE WAKE OF THE SYSTEM
ARE EXPECTED TO ADVECT ACROSS THE TAF SITES DURING THE OVERNIGHT HOURS.
FORECAST SOUNDINGS AND TIME HEIGHTS REMAIN DRY ON WEDNESDAY AS
HIGH PRESSURE MOVES ACROSS THE AREA. A STRONGER STORM SYSTEM WITH
STRONG DYNAMICS ALOFT WILL PUSH INTO THE AREA AFT 06Z
THURSDAY...BRINGING DETERIORATING FLYING CONDITIONS ALONG WITH
CHANCES FOR RAIN. A RETURN TO MVFR LOOKS LIKELY THEN.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...NIELD
NEAR TERM...NIELD
SHORT TERM...NIELD
LONG TERM....RYAN
AVIATION...JP/RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
338 AM EST WED DEC 19 2012
.UPDATE...
THE LONG TERM AND AVIATION SECTIONS HAVE BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 314 PM EST TUE DEC 18 2012
WEAK HIGH PRESSURE IS EXPECTED ACROSS THE AREA INTO WEDNESDAY. A
SIGNIFICANT LOW PRESSURE SYSTEM IS EXPECTED TO MOVE THROUGH THE AREA
AROUND THURSDAY. HIGH PRESSURE IS EXPECTED TO MOVE BACK INTO THE
AREA TOWARDS THE END OF THE WEEK AND ON INTO EARLY NEXT WEEK.
ANOTHER STORM SYSTEM MAY AFFECT THE AREA TOWARDS THE MIDDLE OF NEXT
WEEK.
&&
.NEAR TERM /REST OF TONIGHT/...
ISSUED AT 957 PM EST TUE DEC 18 2012
A RELATIVELY STRONG LOW LEVEL JET BEHIND THE COLD FONT IS
GENERATING WIND GUSTS ACROSS EASTERN ILLINOIS AT THE MOMENT...AND
THESE GUSTS SHOULD TRANSLATE EAST ACROSS THE AREA TONIGHT. THUS
HAVE UPPED WIND GUSTS IN THE GRIDS.
PLENTY OF CLOUDS ARE UPSTREAM OF THE NORTHERN FORECAST AREA...AND
THESE WILL PUSH EAST TONIGHT. HAVE UPPED SKY COVER TO MOSTLY CLOUDY
ACROSS THE NORTH. LEFT PARTLY CLOUDY CENTRAL AS THERE IS SOME
UNCERTAINTY ON HOW FAR SOUTH THEY WILL GET. WENT MOSTLY CLEAR
SOUTH WITH MAINLY HIGH CLOUDS THERE.
TEMPERATURES CONTINUE TO VARY ACROSS THE FORECAST AREA DEPENDING
ON CLOUD COVER AND WINDS. HOWEVER THEY SHOULD LOWER
OVERNIGHT...AND BASED ON LATEST MODEL DATA WENT AHEAD AND BUMPED
MIN TEMPS DOWN A BIT.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
ISSUED AT 314 PM EST TUE DEC 18 2012
MAIN CONCERN DURING THIS PERIOD REVOLVES AROUND STRONG UPPER/SURFACE
SYSTEM THAT IS EXPECTED TO AFFECT THE AREA. THE MODELS TAKE ON THE
TRACK OF THE SURFACE LOW HAVE SHIFTED SOUTHEAST SOME...WITH THE
OPERATIONAL MODELS SUGGESTING A TRACK NEAR CHICAGO ON THURSDAY. THE
ENSEMBLES ARE CLUSTERED AROUND A TRACK THROUGH NORTHWEST
INDIANA...ALTHOUGH A COUPLE OF MEMBERS ARE A LITTLE FARTHER
SOUTHEAST THAN THAT. THE SHIFT SOUTHEAST IN THE TRACK SUGGESTS THE
CHANCES FOR WRAP AROUND SNOW OVER THE AREA THURSDAY NIGHT IS
INCREASING.
IN ADDITION TO THE TRACK SHIFT...THE MODELS ARE A LITTLE SLOWER WITH
THE FRONTAL PASSAGE ON THURSDAY. LIFT NEAR THE FRONTAL ZONE STILL
LOOKS STRONG...SO HIGH POPS FOR LATE WEDNESDAY NIGHT INTO THURSDAY
STILL LOOK GOOD. EMBEDDED THUNDER POSSIBLE GIVEN SOME WEAK ELEVATED
INSTABILITY.
AS MENTIONED ABOVE...WRAP AROUND SNOWS LOOK MORE LIKELY LATE
THURSDAY AFTERNOON AND NIGHT..ESPECIALLY IN THE NORTH. WILL GO WITH
LIKELY POPS IN THE NORTH THURSDAY NIGHT...TAPERING TO CHANCE POPS
SOUTH. SOME MINOR ACCUMULATIONS POSSIBLE...UP TO AN INCH OR SO.
STRONG WINDS EXPECTED IN THE WAKE OF COLD FRONT THURSDAY AFTERNOON
AND NIGHT. MAY BE ABLE TO MIX DOWN WINDS OF 40-45 KTS UNDER STRONG
COLD ADVECTION.
TEMPERATURE FORECAST WILL BE TRICKY...CONSIDERING THE STRONG WARM
AND COLD ADVECTION PATTERNS ASSOCIATED WITH THE STORM SYSTEM. THE
CHANCES ARE GOOD THAT THE GFS MOS HIGHS ON THURSDAY ARE PROBABLY TOO
COOL...AND THE LOWS THURSDAY NIGHT TOO WARM. WILL NUDGE UP THE HIGHS
THURSDAY ABOUT 5 DEGREES...AND TRIM ABOUT 3-5 DEGREES OFF OF THE
LOWS THURSDAY NIGHT. TEMPERATURES EXPECTED TO RISE SLOWLY WEDNESDAY
NIGHT...AND RAPIDLY DROP OFF THURSDAY AFTERNOON.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 338 AM EST WED DEC 19 2012
COLD DRY WEATHER FOR THE WEEKEND FOLLOWED BY AN INCREASINGLY
COMPLEX AND ACTIVE WEATHER REGIME FOR THE FIRST HALF OF NEXT
WEEK...WITH THE POSSIBILITY OF A MAJOR STORM IMPACTING THE REGION
NEAR THE TAIL END OR JUST BEYOND THE EXTENDED PERIOD.
POLAR VORTEX ASSOCIATED WITH THE DEEP LOW PRESSURE THAT WILL
IMPACT THE REGION THURSDAY/FRIDAY WILL SETTLE ACROSS NEW ENGLAND
OVER THE WEEKEND. THE BLOCKY AMPLIFIED FLOW PATTERN ALOFT ACROSS
THE COUNTRY AND INTO THE NORTH ATLANTIC HOWEVER WILL ALLOW THE
UPPER LOW TO MOVE ONLY SLOWLY INTO THE CANADIAN MARITIMES THROUGH
SUNDAY. THIS WILL KEEP THE MIDWEST AND GREAT LAKES IN A NORTHWEST
FLOW ALOFT THROUGH THE WEEKEND WITH HIGH PRESSURE AT THE
SURFACE...RESULTING IN COLD DRY WEATHER FOR CENTRAL INDIANA. HIGHS
WILL LARGELY REMAIN IN THE 30S THIS WEEKEND WITH LOWS IN THE 20S.
SHARP UPPER LEVEL TROUGH OFF THE WEST COAST THIS WEEKEND WILL
SHIFT EAST INTO THE CENTRAL PART OF THE COUNTRY BY TUESDAY...
SETTING THE FRAMEWORK FOR A RESUMPTION OF AN ACTIVE WEATHER
PATTERN FOR MUCH OF THE EASTERN U S BY THE MIDDLE OF NEXT WEEK.
AT LEAST INITIALLY ON MONDAY...THE ECMWF/OP GFS/GGEM ALL DEVELOP A
SURFACE WAVE ACROSS THE MISSISSIPPI VALLEY MOVING INTO THE
EASTERN U S BY TUESDAY. OP GFS AND GGEM BOTH DEEPEN THIS LOW
MORESO THAN THE ECMWF WHICH MAINTAINS A FLATTER FLOW ALOFT AND
KEEPS A WARM FRONT DRAPED TO THE SOUTH OF THE REGION AS THE
AFOREMENTIONED UPPER TROUGH BEGINS TO AMPLIFY OVER THE ROCKIES.
PRESENCE OF THE WAVE WITH INCREASING ISENTROPIC LIFT OVER THE
BOUNDARY WARRANTS A LOW CHANCE POPS MONDAY AND MONDAY NIGHT. WITH
COOL EASTERLY FLOW NORTH OF THE BOUNDARY...WILL CARRY A RAIN/SNOW
MIX.
EXPECT MOISTURE WILL CONTINUE TO INCREASE ON TUESDAY WITH SOUTHWEST
FLOW ALOFT AHEAD OF THE AMPLIFYING UPPER TROUGH ON TUESDAY AND
WILL CARRY CHANCE POPS THROUGH CHRISTMAS. ECMWF AND OP GFS
CONTINUE TO ADVERTISE RAPID CYCLOGENESIS TUESDAY NIGHT INTO
WEDNESDAY OVER THE EASTERN U S BUT AS WOULD BE EXPECTED AT 7-8
DAYS OUT CONTINUE TO DIFFER FROM RUN TO RUN AND WITH EACH OTHER
WITH RESPECT TO SYSTEM TRACK AND TIMING OF IMPACTS. PROVIDING ANY
ADDITIONAL DETAILS IS DIFFICULT AT THIS POINT IN TIME...BUT
NEEDLESS TO SAY WILL CONTINUE TO MONITOR MODEL TRENDS AND PATTERN
EVOLUTION OVER THE NEXT SEVERAL DAYS.
&&
.AVIATION /DISCUSSION FOR THE 190900Z TAF UPDATE/...
ISSUED AT 338 AM EST WED DEC 19 2012
WIND GUSTS EXPERIENCED EARLIER THIS MORNING HAVE DROPPED OFF
SIGNIFICANTLY WITH WINDS BACK TO A 10-15KT RANGE. RAP MODEL
SOUNDINGS AND 950/925MB RH PROGS INDICATE MVFR CEILINGS LIKELY TO
LINGER THROUGH DAYBREAK BEFORE WEAK RIDGING ALLOWS FOR DRYING
INTO THE LOWER LEVELS WITH STRATUS SCATTERING BY LATE MORNING.
WILL ALSO BE REMOVING ANY MENTION OF LOW LEVEL WIND SHEAR AS
925MB JETLET HAS SHIFTED EAST OF THE REGION.
06Z DISCUSSION FOLLOWS.
MVFR CONDITIONS EXPECTED OVERNIGHT...WITH LLWS POSSIBLE. A
RETURN TO VFR IS EXPECTED AFTER 15Z WED.
QUICK MOVING SHORT WAVE AND ASSOCIATED AREA OF LOW PRESSURE WERE
OVER NORTHERN INDIANA AND QUICKLY MOVING EAST. GUSTY WINDS WERE
FOUND IN THE WAKE OF THE SYSTEM. GFS AND NAM SUGGEST A WIND FIELD
OF 40-50 KNTS AT 925MB. THUS HAVE INCLUDED SOME LLWS MENTIONED FOR
SPEED DIFFERENCES. MVFR CIGS OBSERVED IN THE WAKE OF THE SYSTEM
ARE EXPECTED TO ADVECT ACROSS THE TAF SITES DURING THE OVERNIGHT HOURS.
FORECAST SOUNDINGS AND TIME HEIGHTS REMAIN DRY ON WEDNESDAY AS
HIGH PRESSURE MOVES ACROSS THE AREA. A STRONGER STORM SYSTEM WITH
STRONG DYNAMICS ALOFT WILL PUSH INTO THE AREA AFT 06Z
THURSDAY...BRINGING DETERIORATING FLYING CONDITIONS ALONG WITH
CHANCES FOR RAIN. A RETURN TO MVFR LOOKS LIKELY THEN.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...JAS
NEAR TERM...50
SHORT TERM...JAS
LONG TERM....RYAN
AVIATION...JP/RYAN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
139 AM EST WED DEC 19 2012
.SYNOPSIS...
OTHER THAN SOME LINGERING SCATTERED LIGHT MIXED RAIN AND SNOW
SHOWERS EARLY THIS MORNING IN PORTIONS OF CENTRAL NEW YORK...A
BREAK IN THE WEATHER CAN BE EXPECTED TODAY THROUGH AT LEAST MIDDAY
THURSDAY. A STRONG SYSTEM WILL THEN SPREAD LIGHT TO MODERATE RAIN
INTO THE AREA THURSDAY EVENING..BEFORE MIXING WITH AND CHANGING
OVER TO SNOW ON FRIDAY AND INTO THE WEEKEND. A PROLONGED PERIOD OF
SNOW WILL BE POSSIBLE DURING THAT TIME.
&&
.NEAR TERM /THROUGH TONIGHT/...
130AM UPDATE...
WEAK SHORTWAVE IS ADVANCING ACROSS NE OH INTO NW PA WITH A WING OF
VERY LIGHT PRECIP EXTENDING INTO W NY. ALL MODELS INCLUDING THE
HIGH RESOLUTION ONES SUCH AS HRRR SHOW THIS WAVE FALLING APART
WHILE HEADING INTO CENTRAL PA LATER THIS MORNING. SO THE REMAINS
OF PRECIPITATION WILL BE ALMOST ENTIRELY DEPENDING ON LAKE
MOISTURE THIS MORNING. 925MB TEMPERATURES ARE NOW JOINING 850MB BY
DIPPING BELOW ZERO THE NEXT FEW HOURS...BUT SATURATED LAYER IS
ALSO BECOMING VERY SHALLOW TO WHERE ICE CRYSTAL INTRODUCTION WILL
BE A CHALLENGE OUTSIDE OF THE FEW LAKE ENHANCED BANDS THAT EXIST.
THERE IS ONLY ABOUT 12-13 DEG CELSIUS DELTA-T BETWEEN LAKE
TEMPERATURE AND 850MB...JUST BARELY ENOUGH FOR A LAKE RESPONSE
/AND IN THIS CASE...MAINLY CLOUDS AND NOT MUCH PRECIP/.
BOUNDARY LAYER MEANWHILE IS STILL QUITE MILD AS EVIDENCED BY THE
35-40 DEGREE SURFACE TEMPS AT THIS HOUR. EVEN THE HIGHER
ELEVATIONS OF NORTHERN ONEIDA COUNTY SHOULD BE LIMITED TO SEVERAL
TENTHS OF AN INCH OF SNOW ACCUMULATION AT BEST...WITH VAST
MAJORITY SEEING NO ACCUMULATION AT ALL. SOME OF THE RIDGETOPS IN
THE NORTHEASTERN ZONES THAT DIP BELOW FREEZING MAY EVEN SEE PATCHY
FREEZING DRIZZLE AT TIMES EARLY THIS MORNING DUE TO THE DIFFICULTY
PRODUCING ICE CRYSTALS IN SHALLOW SATURATED LAYER.
OTHER THAN THE ABOVE DETAILS WITH LINGERING VERY LIGHT
PRECIPITATION IN PORTIONS OF CENTRAL NEW YORK...WE ARE LOOKING AT
A QUIET PERIOD TODAY THROUGH TONIGHT. LAKE MOISTURE TRAPPED UNDER
DEVELOPING SUBSIDENCE INVERSION FROM INBOUND HIGH PRESSURE WILL
MAKE STRATOCUMULUS A BIT STUBBORN TO BREAK TODAY ESPECIALLY
CENTRAL NEW YORK/NORTHEASTERN ZONES. HIGHS IN UPPER 30S TO LOW
40S...EXCEPT LOW TO MID 30S AT HIGHEST ELEVATIONS.
EVENTUALLY WE CLEAR OUT THIS EVENING...ONLY TO HAVE HIGH CLOUDS
BEGIN TO SPREAD IN VERY LATE TONIGHT FROM THE SOUTHWEST. WENT ON
LOW SIDE OF GUIDANCE FOR MINIMUM TEMPERATURES TONIGHT /MAINLY LOW
TO MID 20S/ AS THERE SHOULD BE A PRETTY GOOD MOSTLY CLEAR WINDOW
FOR RADIATIONAL COOLING BEFORE THE INCREASING HIGH CLOUDS THURSDAY
MORNING.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
330 PM UPDATE...
NEXT SYSTEM MVS IN LATE THUR AFTN, MORE TWD THE EVNG HRS. HV SIDED
WITH THE NAM/ECMWF SOLN DUE TO THE STRENGTH AND DRY AIR ASSOC WITH
THE HIPRES, LEADING TO LATER ARRIVAL OF PCPN. WL GO LKLY/CAT POPS
FOR THUR NGT IN LIGHT-MODERATE RAIN, GRADUALLY MIXING IN WITH SNOW
AFTER 06Z. AS COLD AIR INFILTRATES OVRNGT THUR NGT PCPN SHUD
CHANGEOVER TO ALL SNOW BY 12Z FRIDAY. TEMPS WL RISE SLIGHTLY DRG
THE DAY FRIDAY WITH EXTENSIVE SKY CVR AND COLD AIR/PCPN WRAPPING
ARND THE SYSTEM. UPR LVL TROF GOES NEGATIVE DRG THE DAY ON FRIDAY.
HPC WWD GRAPHICS INDICATING WIDESPREAD 2-6 INCHES CWA-WIDE ALONG
WITH 6-8 INCHES OVR EXTRM NRN ONEIDA CNTY, SIMILAR TO CURRENT SNOW
GRIDS. MAY SEE A PROLONGED PD OF SNOW OVR THE WEEKEND AND WL
HIGHLIGHT IN HWO THIS AFTN. ANY ONE TIME PD MAY SEE ADVISORY/WRNG
EVENTS BUT STILL TOO EARLY TO CALL RIGHT NOW.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
MEDIUM RANGE MODELS SUGGEST GOOD CONFIDENCE IN DEVELOPING A COLD
NORTHWEST FLOW FOR THE DURATION OF THIS LONG TERM FORECAST AS A
CLOSED LOW SETTLES INTO THE CANADIAN MARITIMES OVER THE WEEKEND.
THERE IS DISAGREEMENT IN THE DETAILS AMONGST THE MODELS AND
ENSEMBLE SPREADS...SO WILL FOLLOW THE HPC GUIDANCE PRETTY CLOSELY.
THIS LEANS WITH A ECMWF FLAVOR WHICH MAINTAINS DEEP MOISTURE AND
THE NW FLOW LONGER OVER THE REGION. THERMAL PROFILES AND LAKE
INDUCED INSTABILITY ARE MARGINAL...BUT ENOUGH TO MAINTAIN A LONG
TERM PLUME OF LAKE SNOWS INTO THE UPPER MOHAWK VALLEY AND SYRACUSE
AREA...WITH JUST OCCASIONAL SNOW SHOWERS AND FLURRIES ACROSS CNTRL
NY AND NEPA. THERE LOOKS TO BE SOME PROGRESSIVE RIDGING AND DRYING
MOVING INTO THE AREA EARLY NEXT WEEK WITH A GRADUAL EASING TREND
TO THE SNOW SHOWER COVERAGE AND SOUTHERN EXTENT ACROSS PA.
OVERALL TEMPERATURES LOOK TO BE DECEMBER COLD WITH ONLY MINOR
DIURNAL CHANGES FROM DAY TO DAY. FORECAST CONTAINS TEMPS MAINLY IN
THE 20S...ALTHOUGH AS CLOUDS TEND TO BREAK UP LATER IN THE WEEKEND
IT SHOULD BE COLDER AT NIGHT FROM SUNDAY NIGHT THROUGH TUESDAY
WITH TEMPS IN THE TEENS TO MID 20S.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
1230 AM UPDATE...
A NORTHWEST LOW LEVEL FLOW CONTINUES. A FEW RAIN SHOWERS IN ELMIRA
WHILE A LARGER AREA IS OFF THE EAST END OF LAKE ONTARIO INTO ROME.
ROME COULD HAVE OCCASIONAL IFR CIGS AND MVFR VSBYS IN RAIN SHOWERS
UNTIL 8Z. BGM ELM ITH ALL WILL HAVE MVFR CIGS AT TIMES UNTIL 10Z.
REST OF SITES SHOULD BE MOSTLY VFR. DURING THE DAY CIGS WILL BE
VFR AROUND 4 OR 5 KFT. SKIES CLEAR BRIEFLY LATE TODAY INTO THE
EVENING WITH ONLY SCT MID AND HIGH CLOUDS.
NW WIND AT 10 KTS EARLY THIS MORNING INCREASING LATE MORNING TO 10
TO 12 KTS WITH HIGHER GUSTS. WINDS SUBSIDING LATE IN THE DAY TO 5
TO 10 KTS. ELMIRA SHOULD GO LIGHT AND VARIABLE TONIGHT.
OUTLOOK...
WED NGT/THU...VFR.
THU NGT...VFR DEGRADING TO MVFR/IFR EARLY WITH RAIN DEVELOPING.
FRI/SAT...MVFR. AREAS IFR VSBY IN LAKE EFFECT SNOW.
SUN...VFR/MVFR. SCATTERED SNOW SHOWERS ACROSS CNTRL NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...MDP
NEAR TERM...MDP
SHORT TERM...PVN
LONG TERM...JAB
AVIATION...TAC
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
353 AM MST WED DEC 19 2012
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 353 AM MST WED DEC 19 2012
COOLING CLOUD TOPS ACROSS ERN UT/WRN CO EARLY THIS MORNING
INDICATIVE OF STRONG UPLIFT AS THE UPPER TROUGH WORKS ITS WAY ACROSS
THE GREAT BASIN. LATEST NAM12 AND RAP40 MODELS INDICATE FORCING
PEAKING TOWARD 12Z AS THE 700 MB LOW TRACKS ACROSS WEST-CENTRAL
CO...AND A DEVELOPING SURFACE LOW MOVES EAST ACROSS SE UT/SW CO.
THE ASSOCIATED COLD FRONT WAS CONTINUING TO PUSH SOUTHEAST ACROSS
THE FORECAST AREA EARLY THIS MORNING. SURFACE WINDS HAD SHIFTED TO
THE NW AT MONTROSE AND NUCLA BY 10Z /300 AM/ INDICATING FRONTAL
PASSAGE THERE...AND WAS LIKELY WORKING THROUGH EAGLE. MONTROSE TEMPS
DROPPED FROM 43F. AT 09Z TO 25F. AT 10Z. HEAVY SNOW WAS ACCOMPANYING
THE FRONT...WHICH IS EXPECTED PUSH TROUGH THE 4 CORNERS PRIOR TO
SUNRISE. SHOULD SEE SNOW PICK UP AT VAIL AS THE HEAVIER SNOW BAND IN
EAGLE PUSHES EAST AND FLOW ALOFT BECOMES MORE WESTERLY FOR THEM
TOWARD SUNRISE.
SNOW CEASED AT VERNAL PRIOR TO MIDNIGHT AND CURRENTLY WHICH HAS NE
SURFACE WINDS AT THE MOMENT. BELIEVE THE ERN UINTA BASIN MAY GET ONE
MORE SHOT OF SNOW AS THE Q-G BULLSEYE SHOWN IN THE RAP MODEL SLIDES
BY TO ITS SOUTH TOWARDS 12Z. OTHERWISE...CURRENT HIGHLIGHTS FOR THIS
MORNING LOOK OKAY WITH NO CHANGES PLANNED.
CLEARING SHOULD BE RATHER RAPID BEHIND THE UPPER TROUGH AXIS WHICH
CROSSES WRN CO ABOUT MIDDAY. COLD NW FLOW BEHIND WILL KEEP SNOW
GOING OVER THE MTNS THROUGH THE AFTERNOON...FAVORING THE NW
SLOPES...WHILE DIMINISHING IN THE VALLEYS. ALWAYS HAVE TO KEEP AN
EYE ON THE UNCOMPAGHRE GORGE SOUTH OF OURAY AS FLOW TURNS NW WITH
TROUGH PASSAGE.
HIGH PRESSURE MOVES IN TONIGHT AND THURSDAY ALONG WITH MUCH DRIER
AIR. CLEARING SKIES...COLD AIR...AND FRESH SNOW COVER WILL CAUSE
TEMPS TONIGHT TO PLUMMET TO THE COLDEST READINGS SO FAR THIS SEASON IN
MOST PLACES. STABLE CONDITIONS WILL THE PREVENT THE COLD AIR FROM
MIXING OUT OF THE VALLEYS ON THURSDAY DESPITE SOME WARMING ALOFT.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 353 AM MST WED DEC 19 2012
RIDGE AXIS MOVES DOWNSTREAM THURSDAY NIGHT BUT SURFACE HIGH REMAINS
POSITIONED OVER WRN COLORADO INTO SATURDAY NIGHT. WEST SOUTHWEST
ALOFT RESULTS IN A WARMING AIR MASS...BUT SNOW COVERED VALLEYS WILL
RESULT IN STRONG TEMPERATURE INVERSIONS AND NOT UNUSUAL FOR THE
WARMING IN THE MOS GUIDANCE TO BE SEVERAL DEGREES TOO HIGH.
UNDERCUT THESE VALUES FOR FRIDAY THROUGH SUNDAY...BUT WOULD NOT BE
SURPRISED IF THESE ADJUSTMENTS REMAIN TOO WARM. OTHERWISE BENIGN
WEATHER IS EXPECTED THROUGH THE WEEKEND.
THE GFS AND ECMWF SHOW A PACIFIC WAVE THAT AMPLIFIES AROUND THE FOUR
CORNERS AREA ON MONDAY AND THAT MAY LINGER INTO CHRISTMAS DAY. THE
CANADIAN MODEL IS MUCH MORE AMPLIFIED WITH A DEEP SURFACE LOW
POSITIONED OVER SE UTAH. FAIRLY SIGNIFICANT MODEL SPREADS FOR DAYS
6 AND 7 BUT AGREE THAT MORE WINTER WEATHER RETURNS EARLY NEXT WEEK.
THE SITUATION BEARS WATCHING...BUT CURRENT CONSENSUS OUTPUT SHOWS A
CHANCE FOR SNOW IN THE MOUNTAINS (SLIGHT CHANCE FOR THE VALLEYS) AND
THAT APPEARS SUFFICIENT FOR NOW.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 353 AM MST WED DEC 19 2012
IMPROVING CONDITIONS TODAY WITH VFR CONDITIONS OVER NORTHEAST UTAH
(KVEL) SPREADING SOUTHEAST...BUT MOSTLY AFTER 18Z. WIDESPREAD -SN
WILL KEEP CIGS AND VISIBILITY BELOW AIRPORT MINIMUMS THIS MORNING
ACROSS WRN COLORADO.
KASE/KEGE/KMTJ...OCCASIONAL -SN THROUGH 21Z WITH FREQUENT CIGS AND
VISIBILITY BELOW AIRPORT MINIMUMS. VFR CONDITIONS WILL TAKE HOLD
AFTER 21Z AS SNOW ENDS AND CIGS LIFT AND DISSIPATE.
KGJT/KRIL...OCCASIONAL -SN THROUGH 15Z WITH IFR CONDITIONS
PREVAILING...BUT DIMINISHES BETWEEN 15Z-18Z WITH IMPROVING
VISIBILITY AND LIFTING CIGS. AFTER 18Z...VFR CONDITIONS WILL BE
SPREADING EASTWARD.
KVEL...VFR WILL PREVAIL THROUGH 12Z TONIGHT.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING UNTIL NOON MST TODAY FOR COZ003-006>008-011-
014-020-022-023.
WINTER STORM WARNING UNTIL 6 AM MST EARLY THIS MORNING FOR
COZ001-002.
WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR COZ004-005-
009-010-012-013-017>019.
WINTER WEATHER ADVISORY UNTIL NOON MST TODAY FOR COZ021.
UT...WINTER STORM WARNING UNTIL NOON MST TODAY FOR UTZ025.
WINTER STORM WARNING UNTIL 6 AM MST EARLY THIS MORNING FOR
UTZ023-024.
WINTER STORM WARNING UNTIL 8 AM MST THIS MORNING FOR UTZ027.
WINTER WEATHER ADVISORY UNTIL 8 AM MST THIS MORNING FOR UTZ022-
029.
WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR UTZ028.
&&
$$
SHORT TERM...JAD
LONG TERM...PF
AVIATION...PF
AREA FORECAST DISCUSSION
NWS ALBANY NY
624 AM EST WED DEC 19 2012
.SYNOPSIS...
DRIER CONDITIONS WILL RETURN TODAY AS HIGH PRESSURE BUILDS BACK
INTO EASTERN NEW YORK AND WESTERN NEW ENGLAND. HOWEVER...ANOTHER
POTENT STORM SYSTEM WILL IMPACT THE AREA LATE THURSDAY INTO FRIDAY
WITH SIGNIFICANT PRECIPITATION POSSIBLE. A MUCH COLDER AIR MASS
WILL SETTLE IN FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AMPLE STRATUS REMAINS IN PLACE ACROSS THE MAJORITY OF THE REGION
THIS MORNING. DOWNSLOPING WINDS HAVE RESULTED IN MORE BREAKS IN
THE OVERCAST ACROSS THE CAPITAL REGION AND POINTS SOUTHWARD INTO
THE MID HUDSON VALLEY AND SOUTHERN LITCHFIELD COUNTY. AS SEEN IN
THE H2O VAPOR LOOP...THE MAIN UPPER LOW RESPONSIBLE FOR OUR RECENT
SOGGY WEATHER WAS OVER EASTERN MASSACHUSETTS AND TRACKING INTO
THE GULF OF MAINE. THIS...IN TURN...SHOULD ALLOW FOR SOME
SUBSIDENCE AND SKY IMPROVEMENTS INTO THE VALLEY LOCATIONS AND
PORTIONS OF THE SOUTHERN BERKS AND NW CT THROUGH THE DAY.
FURTHERMORE...LAKE ENHANCED SNOW SHOWERS ACROSS PORTIONS OF THE
DACKS SHOULD FURTHER DIMINISH INTO FLURRIES THROUGH THE MORNING
HOURS FOR THE SAME REASONS JUST MENTIONED. HIGHS THIS AFTERNOON
SHOULD BE ABLE TO OBTAIN LOWER HALF OF THE 40S FOR THE HUDSON
RIVER VALLEY AND 30S ELSEWHERE.
RIDGE ALOFT AND BUILDING SURFACE PRESSURES TO AT LEAST 1024MB SHOULD
ALLOW FOR MOSTLY CLEAR SKIES TO DEVELOP FOR MOST LOCATIONS WITH
SOME LINGERING CLOUDS ACROSS THE DACKS AND THE SOUTHERN GREENS.
OVERNIGHT LOWS SHOULD RANGE FROM THE TEENS ACROSS THE DACKS AND
MIDDLE 20S FOR THE REMAINDER OF THE CWFA.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
POTENT STORM TO IMPACT THE REGION LATE THURSDAY INTO FRIDAY...
ALL AVAILABLE GUIDANCE SUGGEST A RATHER DEEP CYCLONE WILL BE
UNDERWAY ACROSS THE CENTRAL PLAINS AND INTO THE GREAT LAKES REGION
DURING THIS SHORT TERM PORTION OF THE FORECAST.
FURTHERMORE...SECONDARY SURFACE LOW DEVELOPMENT IS EXPECTED ACROSS
THE MID ATLANTIC REGION AND TRACK NORTHWARD ON FRIDAY ACROSS
EASTERN NEW YORK. RATHER IMPRESSIVE LOW LEVEL JET IS EXPECTED TOO
WITH STANDARD DEVIATIONS OF GREATER THAN 5 AND PWAT ANOMALIES OF
1-2 STANDARD DEVIATIONS ABOVE NORMAL PER THE 00Z GEFS ENSEMBLES.
WE BEGIN THIS PERIOD WITH A RATHER TRANQUIL DAY THURSDAY AS THE
AFOREMENTIONED SURFACE AND UPPER LEVEL RIDGE MIGRATE ACROSS THE
REGION. WE WILL LIKELY SEE HIGH LEVEL MOISTURE ON THE INCREASE AND
EVENTUALLY MID LEVEL CLOUDS TOWARD SUNSET. WE WILL KEEP THE
WEATHER DRY AS LATEST TRENDS CONTINUE TO SLOW THE ONSET OF THE
PRECIP FROM THE APPROACHING CENTRAL PLAINS STORM. HIGH
TEMPERATURES WILL RANGE FROM THE 30S ACROSS THE HIGHER TERRAIN AND
LOWER 40S FOR VALLEY LOCATIONS.
IMPRESSIVE LOW LEVEL JET IN EXCESS OF 50 KTS AND MOISTURE TRANSPORT
WILL RESULT IN A QUICKLY ADVANCING ONSET OF PRECIPITATION THURSDAY
NIGHT. WE WILL QUICKLY INCREASE POPS FROM WEST TO EAST THROUGH THE
EVENING. THERMAL PROFILES WILL BE CHALLENGING AS THE COMBINATION
OF DYNAMICAL COOLING AND JUST HOW QUICKLY TEMPERATURES ARE ABLE TO
DROP BEFORE THE ONSET OF PRECIPITATION AND WARM ADVECTION REMAINS
TO BE SEEN. UTILIZING THE WET BULB ZERO PROFILES...THE POSSIBILITY
OF AN ACCUMULATING SNOWFALL EVENT EXISTS FOR THE ADIRONDACKS WITH
SOME FREEZING RAIN POSSIBLE IN THE SHELTERED VALLEYS AND INTO THE
SOUTHERN GREENS OF VERMONT. CONSIDERABLE UNCERTAINTY REMAINS AS WE
WE WILL CONTINUE TO HIGHLIGHT THE HAZARDS INTO THE HWO THIS MORNING.
THE NEXT CONCERN WILL BE PRECIPITATION AMOUNTS. DURING THIS TIME
OF THE YEAR...IT DOES NOT TAKE TOO MUCH RAINFALL TO RESULT IN
POTENTIAL PROBLEMS FOR THE REGION. AT THIS TIME...PRECIPITATION
AMOUNTS WILL RANGE FROM AROUND 1 INCH IN THE VALLEY LOCATIONS UP
TO 3 INCHES FOR THE HIGHER TERRAIN OF THE
CATSKILLS...BERKS...SOUTHERN GREENS AND PERHAPS INTO THE UPSLOPE
REGION OF THE DACKS FROM THE MOHAWK VALLEY. SEE THE HYDRO SECTION
BELOW FOR ADDITIONAL INFORMATION.
LAST CONCERN IS THE INCREASING WIND FIELD. AS PREVIOUSLY
MENTIONED...THE LOW LEVEL SOUTH-SOUTHEAST JET WILL BE IN EXCESS OF
50KTS THURSDAY NIGHT. IT REMAINS DIFFICULT TO DETERMINE WHERE MIXING
OF STRONG WINDS ALOFT MAY OCCUR...BUT WITH A SOUTHEAST FLOW REGIME
FAVORED AREAS SUCH AS THE SOUTHERN GREEN MOUNTAINS...NORTHERN
TACONICS...AND BERKSHIRES MAY HAVE ADVISORY LEVEL WINDS.
DRY SLOT APPROACHES WITH THE SURFACE LOW FRIDAY MORNING. WE EXPECT
A DECREASE IN COVERAGE OF THE PRECIPITATION FROM SOUTH TO NORTH
THROUGH THE MORNING HOURS. MEANWHILE...A RATHER DEEP AND COLD UPPER
LOW WILL MOVE ACROSS THE REGION DURING FRIDAY AFTERNOON. THIS WILL
RESULT IN AN INCREASE IN POPS FROM WEST TO EAST AS THIS UPPER LOW
AND WRAP AROUND MOISTURE MOVE ACROSS THE REGION. BASED ON BUFKIT
PROFILES...TEMPS IN THE VALLEYS SHOULD REMAIN ABOVE FREEZING FOR A
RAIN AND/OR RAIN-SNOW MIXTURE EVOLVING THROUGH THE AFTERNOON
HOURS. TEMPERATURES SHOULD BEGIN TO FALL TOO AS THE THERMAL
PROFILES COOL OFF RATHER QUICKLY THROUGH THE MID AFTERNOON HOURS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE LONG RANGE MODELS START OUT IN EXCELLENT AGREEMENT DURING THE
FIRST PORTION OF THE EXTENDED. HOWEVER...THEY PART PATHS A LITTLE BY
TUESDAY.
THE EXTENDED BEGINS WITH A CLOSED LOW STILL FORECAST TO BE OVER THE
REGION THROUGH SATURDAY...SLOWLY MOVING INTO THE GULF OF MAINE BY
SUNDAY MORNING. THE DEPARTING STORM WILL STILL BE BUFFETING OUR
REGION THROUGH MONDAY WHEN MOVES EVEN FURTHER AWAY AND HIGH PRESSURE
BUILD IN FROM SOUTHERN CANADA.
THIS STORM WILL BRING SNOW SHOWERS...MAINLY TO THE HIGHER ELEVATIONS
AND MOHAWK VALLEY THROUGH THE WEEKEND WITH POTENTIAL FOR MODERATE OR
EVEN LOCALLY HEAVY SNOWFALL ACCUMULATIONS DUE TO A COMBINATION OF
UPSLOPE SNOWS AND LAKE EFFECT SNOW. EVEN PORTIONS OF THE HUDSON
VALLEY COULD SEE LIGHT ACCUMULATIONS OF SNOW IN SOME SECTIONS.
FRIDAY NIGHT A SECONDARY COLD FRONT OR TROUGH IS FORECAST TO MOVE
THROUGH OF OUR REGION. AHEAD OF IT...LAKE EFFECT SNOW SHOWERS AND
UPSLOPE SNOW WILL INITIALLY BE CONFINED TO AREAS WEST OF THE HUDSON
VALLEY AS THE MEAN SURFACE TO 10,000 FEET AGL FLOW IS WSW. THEN...AS
THE SURFACE TROUGH MOVES THROUGH...THE POTENTIAL IS THERE FOR THE
FRONT/TROUGH TO BRING A LINE OF SNOW SHOWERS/SQUALLS THROUGH MUCH OF
THE REGION.
BEHIND THE FRONT...THE MEAN SURFACE TO 10,000 FLOW LOOKS TO TURN
MORE OF A 290 (WNW) MOIST CYCLONIC FLOW. THIS COULD RESULT IN PURE
LAKE EFFECT SNOW COMING INTO THE MOHAWK VALLEY...AND ADDITIONAL
UPSLOPE SNOW SHOWERS IMPACTING THE ADIRONDACKS...SOUTHERN GREENS AND
BERKSHIRES. SATURDAY COULD BE QUITE INTERESTING SINCE THE UPPER LOW
STILL NEARLY OVERHEAD WILL ADD TO BROAD ASCENT ACROSS THE ENTIRE
REGION. SNOW SHOWERS COULD IMPACT MUCH OF THE REGION...PROBABLY MOST
MINIMAL TO THE LEE OF THE CATSKILLS WHERE WE WILL ONLY CARRY SLIGHT
CHANCES DURING THE DAY...WITH POPS INCREASING AS ONE HEADS NORTH
INTO THE CAPITAL DISTRICT AND ESPECIALLY AREAS NORTHWEST (AND EVEN
NORTHEAST OF THE CAPITAL DISTRICT)...WHERE POPS INCREASE TO LIKELY.
THE UPPER AIR LOW PULLS AWAY SATURDAY NIGHT INTO SUNDAY SO WE WILL
GRADUALLY LOOSE THE SYNOPTIC ASCENT. HOWEVER...LAKE EFFECT SNOW
SHOWERS ARE LIKELY TO PERSIST ALONG WITH UPSLOPE SNOWS.
DRIER AIR WORKING ON SUNDAY SHOULD CUT DOWN SNOWFALL RATES MORE BY
SUNDAY NIGHT...BUT ADDITIONAL PESKY SNOW SHOWERS IN THE USUAL PLACES
COULD PERSIST INTO MONDAY.
HIGH PRESSURE IS FORECAST TO BUILD IN MONDAY NIGHT. IT LOOKS QUITE
AND SEASONABLY COLD.
BY TUESDAY...THE 00Z EUROPEAN FORECAST MODELS KEPT HIGH PRESSURE
OVERHEAD AS ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO STAY FAR
ENOUGH AWAY TO KEEP US DRY. THE 00Z GFS HOWEVER RACES THIS FEATURE
IN MUCH FASTER AND WOULD BRING SOME LIGHT PRECIPITATION TO THE
REGION. BELIEVE IT OR NOT...ENOUGH WARM ALOFT MIGHT MEAN A WINTRY
MIX (AS OPPOSED TO ALL SNOW). WHILE LEANING WITH THE EUROPEAN WE
FELT IT WAS PRUDENT TO AT LEAST INCLUDE SLIGHT CHANCES (20) OF
PRECIPITATION ON CHRISTMAS DAY. FOR NOW...JUST CALL IT SLIGHT CHANCE
OF LIGHT SNOW BUT AGAIN...WE STILL FAVOR A DRIER SOLUTION.
TEMPERATURES WILL AT OR SLIGHTLY BELOW SEASONABLE LEVELS THROUGH THE
PERIOD. DAYTIME HIGHS WILL BE 35-40 ON SATURDAY IN THE HUDSON
VALLEY...MID 20S TO LOWER 30S HIGHER TERRAIN. TEMPERATURES WILL BE
IN THE 20S IN THE VALLEYS SATURDAY NIGHT...TEENS HIGHER TERRAIN.
EVEN COLDER WEATHER EXPECTED ON SUNDAY WITH HIGHS ONLY 30-35 ALBANY
SOUTHWARD...20S HIGHER TERRAIN AND AREAS NORTH OF THE CAPITAL
DISTRICT. MONDAY NIGHT COULD FEATURE THE COLDEST NIGHT OF THE YOUNG
WINTER SEASON THUS FAR...TEENS AND SINGLE NUMBERS EVERYWHERE
NORTH...WEST AND EAST OF THE CAPITAL DISTRICT...20-25 ALBANY AND
POINTS SOUTH. TUESDAY WILL FEATURE HIGH TEMPS SIMILAR TO THOSE OF
MONDAY.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
THE BIG WEATHER PROBLEM OF THE DAY WILL BE GUSTY NORTHWEST
WINDS...FORECASTED TO BE 20-25KTS...POSSIBLY GUSTING OVER 30KTS AT
TIMES AT KALB AND KPSF THROUGHOUT THE MAJORITY OF THE DAY.
A DEPARTING LOW PRESSURE WILL BUFFET THE REGION TODAY. AT THIS
POINT...WE BELIEVE MAINLY VFR CONDITIONS WILL PREVAIL AT MOST TAF
SITES TODAY. THE EXCEPTION WILL BE AT KPSF WHICH WILL START THE DAY
WITH IFR CONDITIONS THROUGH ABOUT 14Z DUE TO UPSLOPE SNOW SHOWER
ACTIVITY. THE LATEST LAV GUIDANCE AND EXPERIMENTAL HRRR INDICATED
THESE SHOWERS OF SNOW SHOULD END BY 14Z. RADAR RETURNS INDICATED
THAT SNOW SHOWERS WERE WANING OVER THIS AREA...AT LEAST AT THE TIME
OF THIS DISCUSSION.
AFTER 14Z...LOOK FOR CLOUDS BASES TO BE ABOUT 3500-4000
FEET...SCT-BKN AT KGFL AND KALB...MAINLY SCT AT KPOU. AT KPSF WE
THINK BKN-OVC BASES WILL BE CLOSER TO 3000 FEET SO CONDITIONS WILL
REMAIN AT MVFR MUCH OF THE DAY...BUT HOPEFULLY AT THE HIGH END OF
MVFR.
THE GUSTY WIND WILL DIMINISH TO UNDER 10KTS BEFORE 00Z AT KPOU AND
KGFL...NOT UNTIL ABOUT 02Z AT KALB/KPSF. AT THE SAME TIME...WE
BELIEVE CLOUDS WILL BECOME FEW-SCT. THESE CONDITIONS WILL PREVAIL
THROUGH THE NIGHT.
OUTLOOK...
WED-THU...VFR...NO SIG WX.
THU NITE-FRI AM...SUB-VFR. CIG. RA LIKELY POSSIBLY ENDING AS -SN.
BCMG WINDY.
FRI PM-SUN...VFR. CHC SUB-VFR -SHSN CIG. WINDY.
&&
.HYDROLOGY...
ONLY MINOR RISES OCCURRED ON AREA RIVERS WITH THE STEADY RAINFALL
THAT ENDED THIS MORNING. HOWEVER...THIS WILL PRIME CONDITIONS FOR
BETTER RUNOFF POTENTIAL LATER THIS WEEK. DRY CONDITIONS ARE EXPECTED
FROM TODAY INTO MUCH OF THURSDAY...EXCEPT FOR SOME SNOW SHOWERS OVER
THE MOUNTAINS OF THE DACKS AND SOUTHERN GREENS.
THE NEXT STORM SYSTEM APPROACHES THURSDAY NIGHT INTO FRIDAY WITH
POTENTIALLY SIGNIFICANT QPF INCLUDING A WINTRY MIX OR RAINFALL TO
START AND SNOW TO END. DETAILS ARE STILL NOT CERTAIN AT THIS TIME.
SHOULD SIGNIFICANT RAINFALL OCCUR...SOME HYDRO PROBLEMS MAY DEVELOP.
AS OF NOW...QPF WITH THIS SYSTEM IS EXPECTED TO BE BETWEEN 1 AND 2
INCHES ACROSS THE AREA WITH AS HIGH AS 3 INCHES POSSIBLE FOR THE
CATSKILLS. HIGH RIVER FLOWS ARE EXPECTED BY THE END OF THE WORK
WEEK...AND WE WILL HAVE TO MONITOR POTENTIAL FOR SOME FLOODING.
RUNOFF SHOULD SLOW ON SATURDAY...AS A VERY COLD AIR MASS MOVES INTO
THE REGION. SOME BODIES OF WATER MAY EVEN START TO FORM ICE LATER IN
THE WEEKEND.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...BGM
NEAR TERM...BGM
SHORT TERM...BGM
LONG TERM...HWJIV
AVIATION...HWJIV
HYDROLOGY...BGM/JPV
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1029 AM EST WED DEC 19 2012
.SYNOPSIS...
A BREAK IN THE WEATHER CAN BE EXPECTED THROUGH TONIGHT AS HIGH
PRESSURE BUILDS ACROSS THE REGION. FAIR AND CHILLY WEATHER WILL
LAST INTO THURSDAY. THEN A STRONG STORM SYSTEM WILL SPREAD LIGHT
TO MODERATE RAIN ACROSS THE AREA THURSDAY NIGHT INTO FRIDAY
MORNING. COLDER AIR ON THE BACK SIDE OF THIS SYSTEM WILL CHANGE
RAIN SHOWERS TO SNOW DURING THE DAY FRIDAY...WITH ACCUMULATING
SNOW SHOWERS FOR MUCH OF THE AREA FRIDAY NIGHT INTO THE
WEEKEND...ESPECIALLY FOR CENTRAL NEW YORK.
&&
.NEAR TERM /THROUGH TONIGHT/...
1000 AM UPDATE...LASTEST RAP MODEL SHOWS A NORTHWEST FLOW OF AIR
FROM THE SFC THRU THE MID TROPOSPHERE BEHIND THE DEPARTING CYCLONE
OFF THE NEW ENGLAND COAST. THERE REALLY WASN`T THAT MUCH COLD AIR
UNDER AN INVERSION WHICH WAS FORECAST TO RISE TO ARND 850 MB BY
AFTERNOON AS PER LATEST RAP BUFKIT SOUNDING DATA...THEN DROP OFF
TOWARD EVENING AS SUBSDC KICKS WITH AN APPRACHING RDG WHICH
EXTENDS FROM THE SFC THTU 500 MB. THUS WE REALLY DON/T SEE ANY
PRECIP WITH LES WITH 850 MB TEMPS ARND -6 TO -7C WHICH GIVES VERY
MARGINAL 13-14C DIFFERENTIALS. THE LATEST SPORT SST/S SHOW LAKE
ONTARIO ARND 7-8C. SO I CAN SEE SC COMING DOWN OFF THE LAKE IN
ADDTN TO MORE SC DEVELOPING WITH SOME INSOLATION THIS AFTERNOON.
TEMPERATURES WILL RISE JUST A DEGREES AS THE DIURNAL TREND IS
FIGHTING CAA. SO MAINLY A PS TO MC AFTERNOON WITH CHILLY BUT
SLIGHTLY ABOVE NORMAL TEMPERATURES.
FOR TONIGHT...RDG BUILDS IN FROM THE SFC THRU 500 MB AND SKIES
SHUD TRY TO CLEAR OUT. THERE STILL WILL BE SOME FLOW OFF LAKE
ONTARIO SO SOME LAKE CLOUDS LIKELY WILL BE ARND MUCH OF THE NGT SO
WON/T GO COMPLETELY CLR. THIS WILL KEEP MINS FROM DROPPING BELOW
THE 20S WHICH IS ABOVE NORMAL AS WELL.
700AM UPDATE...
A WEAK SHORTWAVE ADVANCED FROM NE OH INTO CENTRAL PA AND FELL
APART...SO THE REMAINS OF LIGHT PRECIPITATION IS ALMOST ENTIRELY
DEPENDENT ON LAKE MOISTURE THIS MORNING. 925MB TEMPERATURES HAVE
DIPPED SLIGHTLY BELOW ZERO...BUT SATURATED LAYER IS ALSO SHALLOW
TO WHERE ICE CRYSTAL INTRODUCTION IS A CHALLENGE. THERE IS ONLY
ABOUT 12-13 DEG CELSIUS DELTA-T BETWEEN LAKE TEMPERATURE AND
850MB...JUST BARELY ENOUGH FOR A LAKE RESPONSE /AND IN THIS
CASE...MAINLY CLOUDS AND NOT MUCH PRECIP/. THE FEW SPRINKLES AND
PERHAPS FLURRIES NORTH OF A SYRACUSE-NORWICH-DELHI LINE WILL COME
TO AN END QUICKLY THIS MORNING. WHERE THERE IS CLOUD
COVER...TEMPERATURES ARE STILL ABOVE FREEZING EARLY THIS MORNING.
OTHER THAN THE ABOVE DETAILS...WE ARE LOOKING AT A QUIET PERIOD
TODAY THROUGH TONIGHT. LAKE MOISTURE TRAPPED UNDER DEVELOPING
SUBSIDENCE INVERSION FROM INBOUND HIGH PRESSURE WILL MAKE
STRATOCUMULUS A BIT STUBBORN TO BREAK TODAY IN THE NORTHEASTERN
ZONES...BUT THERE HAS ALREADY BEEN SOME SUCCESS ELSEWHERE WHICH
WILL ALLOW SOME SUNSHINE TO MIX IN TODAY. HIGHS IN UPPER 30S TO
LOW 40S...EXCEPT LOW TO MID 30S AT HIGHEST ELEVATIONS.
EVENTUALLY WE CLEAR OUT THIS EVENING...ONLY TO HAVE HIGH CLOUDS
BEGIN TO SPREAD IN VERY LATE TONIGHT FROM THE SOUTHWEST. WENT ON
LOW SIDE OF GUIDANCE FOR MINIMUM TEMPERATURES TONIGHT /MAINLY LOW
TO MID 20S/ AS THERE SHOULD BE A PRETTY GOOD MOSTLY CLEAR WINDOW
FOR RADIATIONAL COOLING BEFORE THE INCREASING HIGH CLOUDS THURSDAY
MORNING.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
445 AM UPDATE...
I HAVE BEEN ABLE TO FURTHER CONTINUE TO TREND OF LATER ARRIVAL OF
PRECIPITATION WITH NEXT INBOUND SYSTEM...TO POINT THAT OTHER THAN
SLIGHT CHANCE IN WESTERN ZONES...ALL RAINFALL SHOULD BE WAIT UNTIL
AFTER DARK THURSDAY. CLOUDS WILL THICKEN THROUGH THE DAY
HOWEVER...VERY MUCH LIMITING AMOUNT OF HEATING AT THE SURFACE. IN
FACT...SURFACE HIGH OVER NEW ENGLAND JUXTAPOSED WITH THE DEEPENING
LOW IN THE GREAT LAKES...WILL ALLOW COLD AIR DAMMING TO SET UP
AGAINST THE CATSKILLS AND POCONOS INTO THURSDAY NIGHT. SOLID BATCH
OF RAIN /RANGING FROM THREE-QUARTERS OF AN INCH TO AN INCH-
AND-A-THIRD/ COMES THROUGH THURSDAY NIGHT THROUGH FRIDAY
MORNING...BUT DUE TO COLD AIR DAMMING WE WILL HAVE TO WATCH THE
EDGES OF NORTHEASTERN ZONES FOR POTENTIAL OF TEMPERATURE DROPPING
TO NEAR FREEZING AS THE RAIN COMES THROUGH...THUS AT LEAST A
CHANCE OF FREEZING RAIN/SLEET FOR A TIME THERE.
AS FOR CHANGEOVER OF RAIN TO SNOW...MODELS SUGGEST A DELAYED
ARRIVAL OF THE NECESSARY COLD AIR ADVECTION TO SUPPORT CHANGEOVER
/THOUGH NAM IS QUITE A BIT COLDER THAN THE OTHER MODELS AND MIGHT
SUPPORT EARLIER/. THOUGH MINOR WET SNOW ACCUMULATIONS MAY BEGIN
LATE THURSDAY NIGHT INTO FRIDAY MORNING AT HIGHER ELEVATIONS...BEST
AREAWIDE SNOW ACCUMULATION POTENTIAL WILL BE FRIDAY AFTERNOON INTO
PARTICULARLY FRIDAY NIGHT /AND BEYOND/...ESPECIALLY CENTRAL NEW
YORK. MOST OF AREA WILL ENTER THE DRY SLOT OF THE SYSTEM DURING
THE MIDDLE OF THE DAY FRIDAY...FURTHER PUTTING FOCUS MORE INTO LATE
FRIDAY THROUGH FRIDAY NIGHT FOR SNOW ACCUMULATIONS...WHEN DEEPER
MOISTURE OF THE LARGE COMMA HEAD OF THE SYSTEM MOVES BACK OVER THE
REGION.
WE HAVE CONTINUED MENTION OF ACCUMULATING SNOW IN THE
HAZARDOUS WEATHER OUTLOOK /MAINLY CENTRAL NEW YORK/...AND AT
THIS POINT AT LEAST ADVISORY LEVEL SNOW LOOKS QUITE
POSSIBLE...PARTICULARLY FINGER LAKES THROUGH MOHAWK VALLEY/TUG
HILL REGIONS. STAY TUNED FOR FORECAST UPDATES AS THIS EVENT GETS
CLOSER.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
3 AM UPDATE...
ONLY MINOR CHANGES WITH MODELS AND HPC ALL SIMILAR ESPECIALLY THE
FIRST HALF OF THE LONG TERM. UNSETTLED WINTRY PERIOD. SATURDAY TO
MONDAY IN DEEP NORTHWEST FLOW. THIS ON THE BACK SIDE OF A DEEP
CLOSED UPPER LEVEL TROF OVER NEW ENGLAND. IT LIFTS EAST MONDAY
BRINGING A ZONAL FLOW AND AN END TO THE LAKE EFFECT. MOST OF THE CWA
WILL HAVE SNOW SHOWERS WITH ACCUMULATIONS LIKELY ESPECIALLY IN
CENTRAL NY. THIS SNOW COVER COULD MEAN TEMPERATURES ALREADY NEAR
NORMAL MAY BE COLDER THAN FORECASTED. TUESDAY A BREAK BEFORE THE
NEXT DEEP TROF BRINGS ANOTHER RAIN TO SNOW THEN LAKE EFFECT SNOW
SHOWER SCENARIO STARTING WEDNESDAY.
PREVIOUS DISCUSSION...
MEDIUM RANGE MODELS SUGGEST GOOD CONFIDENCE IN DEVELOPING A COLD
NORTHWEST FLOW FOR THE DURATION OF THIS LONG TERM FORECAST AS A
CLOSED LOW SETTLES INTO THE CANADIAN MARITIMES OVER THE WEEKEND.
THERE IS DISAGREEMENT IN THE DETAILS AMONGST THE MODELS AND
ENSEMBLE SPREADS...SO WILL FOLLOW THE HPC GUIDANCE PRETTY CLOSELY.
THIS LEANS WITH A ECMWF FLAVOR WHICH MAINTAINS DEEP MOISTURE AND
THE NW FLOW LONGER OVER THE REGION. THERMAL PROFILES AND LAKE
INDUCED INSTABILITY ARE MARGINAL...BUT ENOUGH TO MAINTAIN A LONG
TERM PLUME OF LAKE SNOWS INTO THE UPPER MOHAWK VALLEY AND SYRACUSE
AREA...WITH JUST OCCASIONAL SNOW SHOWERS AND FLURRIES ACROSS CNTRL
NY AND NEPA. THERE LOOKS TO BE SOME PROGRESSIVE RIDGING AND DRYING
MOVING INTO THE AREA EARLY NEXT WEEK WITH A GRADUAL EASING TREND
TO THE SNOW SHOWER COVERAGE AND SOUTHERN EXTENT ACROSS PA.
OVERALL TEMPERATURES LOOK TO BE DECEMBER COLD WITH ONLY MINOR
DIURNAL CHANGES FROM DAY TO DAY. FORECAST CONTAINS TEMPS MAINLY IN
THE 20S...ALTHOUGH AS CLOUDS TEND TO BREAK UP LATER IN THE WEEKEND
IT SHOULD BE COLDER AT NIGHT FROM SUNDAY NIGHT THROUGH TUESDAY
WITH TEMPS IN THE TEENS TO MID 20S.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
630 AM UPDATE...
A NORTHWEST LOW LEVEL FLOW CONTINUES. SHOWERS ON RADARS
DIMINISHING AND WILL NOT INCLUDE IN TAFS. BGM AND ITH WILL HAVE
MVFR CIGS AT TIMES UNTIL AROUND 14Z. REST OF SITES SHOULD BE
MOSTLY VFR WITH CIGS AROUND 4 OR 5 KFT. SKIES CLEAR BRIEFLY LATE
TODAY INTO THE EVENING WITH ONLY SCT MID AND HIGH CLOUDS. BROKEN
TO OVERCAST MID AND HIGH CLOUDS COME IN LATE TONIGHT.
NW WIND AT 10 KTS EARLY INCREASING LATE MORNING TO 10 TO 12 KTS
WITH HIGHER GUSTS. WINDS SUBSIDING LATE IN THE DAY TO 5 TO 10 KTS.
ELMIRA SHOULD GO LIGHT AND VARIABLE TO CALM THIS EVENING...AND
MOST OF OTHER SITES LATE TONIGHT WITH SURFACE HIGH PRESSURE.
OUTLOOK...
THU...VFR.
THU NGT...VFR DEGRADING TO MVFR/IFR EARLY WITH RAIN DEVELOPING.
FRI/SAT...MVFR. AREAS IFR VSBY IN LAKE EFFECT SNOW.
SUN...VFR/MVFR. SCATTERED SNOW SHOWERS ACROSS CNTRL NY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN/MDP
SHORT TERM...MDP
LONG TERM...JAB/TAC
AVIATION...TAC
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
958 AM MST WED DEC 19 2012
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 353 AM MST WED DEC 19 2012
COOLING CLOUD TOPS ACROSS ERN UT/WRN CO EARLY THIS MORNING
INDICATIVE OF STRONG UPLIFT AS THE UPPER TROUGH WORKS ITS WAY ACROSS
THE GREAT BASIN. LATEST NAM12 AND RAP40 MODELS INDICATE FORCING
PEAKING TOWARD 12Z AS THE 700 MB LOW TRACKS ACROSS WEST-CENTRAL
CO...AND A DEVELOPING SURFACE LOW MOVES EAST ACROSS SE UT/SW CO.
THE ASSOCIATED COLD FRONT WAS CONTINUING TO PUSH SOUTHEAST ACROSS
THE FORECAST AREA EARLY THIS MORNING. SURFACE WINDS HAD SHIFTED TO
THE NW AT MONTROSE AND NUCLA BY 10Z /300 AM/ INDICATING FRONTAL
PASSAGE THERE...AND WAS LIKELY WORKING THROUGH EAGLE. MONTROSE TEMPS
DROPPED FROM 43F. AT 09Z TO 25F. AT 10Z. HEAVY SNOW WAS ACCOMPANYING
THE FRONT...WHICH IS EXPECTED PUSH TROUGH THE 4 CORNERS PRIOR TO
SUNRISE. SHOULD SEE SNOW PICK UP AT VAIL AS THE HEAVIER SNOW BAND IN
EAGLE PUSHES EAST AND FLOW ALOFT BECOMES MORE WESTERLY FOR THEM
TOWARD SUNRISE.
SNOW CEASED AT VERNAL PRIOR TO MIDNIGHT AND CURRENTLY WHICH HAS NE
SURFACE WINDS AT THE MOMENT. BELIEVE THE ERN UINTA BASIN MAY GET ONE
MORE SHOT OF SNOW AS THE Q-G BULLSEYE SHOWN IN THE RAP MODEL SLIDES
BY TO ITS SOUTH TOWARDS 12Z. OTHERWISE...CURRENT HIGHLIGHTS FOR THIS
MORNING LOOK OKAY WITH NO CHANGES PLANNED.
CLEARING SHOULD BE RATHER RAPID BEHIND THE UPPER TROUGH AXIS WHICH
CROSSES WRN CO ABOUT MIDDAY. COLD NW FLOW BEHIND WILL KEEP SNOW
GOING OVER THE MTNS THROUGH THE AFTERNOON...FAVORING THE NW
SLOPES...WHILE DIMINISHING IN THE VALLEYS. ALWAYS HAVE TO KEEP AN
EYE ON THE UNCOMPAGHRE GORGE SOUTH OF OURAY AS FLOW TURNS NW WITH
TROUGH PASSAGE.
HIGH PRESSURE MOVES IN TONIGHT AND THURSDAY ALONG WITH MUCH DRIER
AIR. CLEARING SKIES...COLD AIR...AND FRESH SNOW COVER WILL CAUSE
TEMPS TONIGHT TO PLUMMET TO THE COLDEST READINGS SO FAR THIS SEASON IN
MOST PLACES. STABLE CONDITIONS WILL THE PREVENT THE COLD AIR FROM
MIXING OUT OF THE VALLEYS ON THURSDAY DESPITE SOME WARMING ALOFT.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 353 AM MST WED DEC 19 2012
RIDGE AXIS MOVES DOWNSTREAM THURSDAY NIGHT BUT SURFACE HIGH REMAINS
POSITIONED OVER WRN COLORADO INTO SATURDAY NIGHT. WEST SOUTHWEST
ALOFT RESULTS IN A WARMING AIR MASS...BUT SNOW COVERED VALLEYS WILL
RESULT IN STRONG TEMPERATURE INVERSIONS AND NOT UNUSUAL FOR THE
WARMING IN THE MOS GUIDANCE TO BE SEVERAL DEGREES TOO HIGH.
UNDERCUT THESE VALUES FOR FRIDAY THROUGH SUNDAY...BUT WOULD NOT BE
SURPRISED IF THESE ADJUSTMENTS REMAIN TOO WARM. OTHERWISE BENIGN
WEATHER IS EXPECTED THROUGH THE WEEKEND.
THE GFS AND ECMWF SHOW A PACIFIC WAVE THAT AMPLIFIES AROUND THE FOUR
CORNERS AREA ON MONDAY AND THAT MAY LINGER INTO CHRISTMAS DAY. THE
CANADIAN MODEL IS MUCH MORE AMPLIFIED WITH A DEEP SURFACE LOW
POSITIONED OVER SE UTAH. FAIRLY SIGNIFICANT MODEL SPREADS FOR DAYS
6 AND 7 BUT AGREE THAT MORE WINTER WEATHER RETURNS EARLY NEXT WEEK.
THE SITUATION BEARS WATCHING...BUT CURRENT CONSENSUS OUTPUT SHOWS A
CHANCE FOR SNOW IN THE MOUNTAINS (SLIGHT CHANCE FOR THE VALLEYS) AND
THAT APPEARS SUFFICIENT FOR NOW.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 958 AM MST WED DEC 19 2012
BACK EDGE OF THIS STORM IS MOVING THROUGH NORTHWEST COLORADO LATE
THIS MORNING WITH IMPROVING CONDITIONS SPREADING SLOWLY
SOUTHEASTWARD. KVEL...KRIL AND KGJT TERMINALS WILL REMAIN VFR
THROUGH THE NEXT 24 HOURS...THOUGH THE THREAT OF LOCALIZED FOG CAN
NOT BE RULED OUT OVERNIGHT AS SKIES CLEAR. AT THE REMAINDER OF THE
TERMINAL FORECAST SITES IFR/LIFR CONDITIONS WILL REMAIN IN PLACE
THROUGH AT LEAST THE EARLY AFTERNOON HOURS. SLOW IMPROVEMENT
IS EXPECTED AT KMTJ AND KEGE FIRST WITH ASPEN RAISING ABOVE
AIRPORT MINIMUMS BY SUNSET...WITH THE 18Z TAFS REFLECTING THESE
TRENDS. MOUNTAIN AND HIGH PASS OBSCURATIONS WILL CONTINUE INTO THE
EARLY EVENING HOURS BEFORE CLEARING MOVE OVER THE DIVIDE AS THE
STORM TAKES ON THE PLAINS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING UNTIL NOON MST TODAY FOR COZ003-006>008-011-
014-020-022-023.
WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR COZ004-005-
009-010-012-013-017>019.
WINTER WEATHER ADVISORY UNTIL NOON MST TODAY FOR COZ021.
UT...WINTER STORM WARNING UNTIL NOON MST TODAY FOR UTZ025.
WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR UTZ028.
&&
$$
SHORT TERM...JAD
LONG TERM...PF
AVIATION...15
AREA FORECAST DISCUSSION
NWS TOPEKA KS
425 PM CST WED DEC 19 2012
.DISCUSSION...
A VERY POTENT AND SIGNIFICANT WINTER STORM SET TO IMPACT THE AREA
WEDNESDAY NIGHT INTO THURSDAY MORNING...BRINGING PERIODS OF HEAVY
SNOW AND VERY STRONG WINDS. NEAR BLIZZARD CONDITIONS WILL BE LIKELY
ACROSS ALL OF NORTH CENTRAL...NORTHEAST...AND EAST CENTRAL KANSAS.
SHORT TERM FORECAST (TONIGHT THROUGH TOMORROW)...
AT 22Z A SURFACE TROUGH WAS UNDERGOING LEE SIDE CYCLOGENESIS IN FAR
NORTHWEST OKLAHOMA. THE STRONG PRESSURE GRADIENT ON THE NORTHERN AND
WESTERN EDGE OF THE LOW IS PRODUCING STRONG WINDS ACROSS WESTERN
NEBRASKA AND WESTERN KANSAS. RADAR TRENDS INDICATE THAT
PRECIPITATION HAS COMMENCED ACROSS CENTRAL AND SOUTHERN NEBRASKA AND
SURFACE OBS INDICATE THE SNOW LINE AT THIS POINT RUNS FROM KROK TO
KGCK. AS THE SURFACE LOW DEEPENS AND MOVES TO THE EAST THE FREEZING
LINE WILL SHIFT TO THE SOUTHEAST WITH IT. BANDED PRECIPITATION
ACROSS NORTHERN KANSAS AND CENTRAL NEBRASKA LOOKS TO BE IN RESPONSE
TO STRONG ISENTROPIC ASCENT ALONG WITH GOOD 850 TO 700 MB
FRONTOGENETICAL LIFT. ALOFT RAP ANALYSIS INDICATES THE STRONG MID
LEVEL TROUGH IS CURRENTLY OVER THE GREAT DIVIDE...PUSHING INTO THE
CENTRAL HIGH PLAINS. AS THIS TROUGH PUSHES EASTWARD IT WILL CONTINUE
TO DEEPEN TO AROUND 536 DM OVER WESTERN MISSOURI OVERNIGHT. AS THIS
MID/UPPER TROUGH COMES THROUGH THE AREA A VERY STRONG PV ANOMALY
WILL GLIDE JUST SOUTH OF THE AREA...INDICATING THE BEST MID/UPPER
ASCENT JUST NORTH OF THE PV ANOMALY CENTER.
MODELS HAVE BEEN FAIRLY CONSISTENT REGARDING THE SCENARIO FOR
WEDNESDAY NIGHT INTO THURSDAY. THE PREVIOUSLY MENTIONED SURFACE
TROUGH IS EXPECTED TO REMAIN STEADY STATE OR POSSIBLY EVEN DEEPEN A
BIT AS IT MOVES ACROSS NORTHERN OKLAHOMA. IT WILL TAKE A TURN TO THE
NORTH AND MOVE NORTHEAST ALONG INTERSTATE 44 OVERNIGHT. STRONG
TRANSPORT VECTORS BOTH AT THE SURFACE AND AT 850 MB WILL BRING A
GOOD AMOUNT OF MOISTURE INTO THE EASTERN FLANK OF THE STRONG LOW
LEVEL CYCLONE. THE WARM/MOIST CONVEYOR BELT WILL TRANSPORT THE
MOISTURE AROUND THE NORTHERN FLANK OF THE LOW LEVEL CYCLONE AND
INTRODUCE IT TO THE COLD AIR ON THE NORTHWESTERN AND WESTERN SIDE OF
THE LOW LEVEL TROUGH. THE BETTER/DEEPER MOISTURE WILL ALSO DEFINE A
DECENT WARM SECTOR...WHICH WILL TAKE SHAPE MAINLY ALONG AND EAST OF
THE KANSAS TURNPIKE THIS EVENING. BETWEEN ROUGHLY 00Z AND 06Z THE
AREA SOUTH AND EAST OF THE KANSAS TURNPIKE WILL LIKELY EXPERIENCE A
PERIOD OF RAIN...WITH SOME THUNDERSTORMS. WITH 500 TO 1000 J/KG OF
MU CAPE RESIDING IN THE WARM SECTOR A FEW OF THE THUNDERSTORMS COULD
BECOME STRONG...ESPECIALLY GIVEN THE VERY STRONG DEEP LAYER SHEAR.
AS THE COLD AIR QUICKLY SHIFTS EASTWARD LIQUID PRECIPITATION WILL
QUICKLY CHANGE OVER TO SNOW...WITH POTENTIALLY A BRIEF PERIOD OF
SLEET IN THE TRANSITION PERIOD. THIS TRANSITION WILL LIKELY OCCUR
AROUND KMHK AROUND 05Z...WITH A CHANGE OVER AT KTOP AND KLWC BETWEEN
07Z AND 08Z. NAM CROSS SECTIONS INDICATE A FEW AREAS WITH CONVECTIVE
INSTABILITY RESIDING ALONG THE INTERSTATE 70 CORRIDOR BETWEEN 09Z
AND 12Z. THIS IS THE TIME PERIOD TARGETED AS THE PERIOD OF HEAVIEST
SNOW ACROSS THE FAR EASTERN PORTION OF THE STATE. ACROSS NORTH
CENTRAL KANSAS GOOD MID LEVEL FRONTOGENESIS AND THE AFOREMENTIONED
PV ANOMALY WILL BE THE PRIMARY MODES OF LIFT. ALTHOUGH THE OVERALL
LIFT FROM THIS SYSTEM WILL BE QUITE ROBUST ITS PROGRESSIVE NATURE
WILL HELP KEEP SNOW AMOUNTS TO A MANAGEABLE 4 TO 6 INCHES ALONG AND
NORTH OF HIGHWAY INTERSTATE 70 AND IN THE 1 TO 3 INCH RANGE ALONG
AND SOUTH OF INTERSTATE 35. EXPECT THE HEAVY SNOW TO COME TO AN END
BY 12Z ACROSS THE ENTIRE AREA...WITH LINGERING SNOW LIKELY COMING TO
AN END BY 15Z THURSDAY.
AGGRAVATING THE PERIL OF THIS SYSTEM ARE THE VERY STRONG WINDS
ASSOCIATED WITH THE LOW LEVEL CYCLONE. MODELS CONTINUE TO INDICATE
SURFACE WINDS BEING SUSTAINED AT 30 TO 40 MPH. 925 MB WINDS ARE ALSO
PROGGED TO BE IN THE 50 TO 60 KT RANGE...WITH 850 MB WINDS REACHING
70 KTS. DEEP MIXING WILL LIKELY NOT OCCUR...BUT WITH LOW LEVEL WINDS
BEING SO STRONG ITS CONCEIVABLE THAT 50 MPH GUSTS WILL BE POSSIBLE
IN CONCURRENCE WITH THE MODERATE TO HEAVY SNOW. THE COMBINATION OF
THESE FACTORS WILL BRING NEAR BLIZZARD CONDITIONS TO ALMOST THE
ENTIRE AREA...WITH AREAS RECEIVING THE HEAVIEST SNOW HAVING THE MOST
LIMITED VISIBILITIES. CONSIDERATION OF AN UPGRADE TO BLIZZARD
WARNING WAS MADE HOWEVER THE EXPECTED SHORT DURATION OF THE
CONDITIONS (ON THE ORDER OF 3 TO 5 HOURS) PRECLUDED THAT UPGRADE.
THE CONSISTENCY OF THE MODELS TO THIS POINT HAVE BEEN GOOD...BUT THE
18Z RUN OF THE NAM CAME IN MUCH MORE ROBUST REGARDING THE
PRECIPITATION OUTPUT AND WIND FORECAST. WILL CONTINUE TO MONITOR THE
EVOLUTION OF THIS SYSTEM AND PROVIDE UPDATES AS NECESSARY.
JL
THURSDAY...
SNOW WILL LINGER IN EXTREME KANSAS THROUGH MID MORNING WITH VERY
STRONG WINDS GUSTING TO 45 MPH OR GREATER IN FAR EASTERN KANSAS AS
WELL. THE SNOW SHOULD END BY 9 AM OR SO...WITH WINDS GRADUALLY
DECREASING AFTER THAT POINT AS WELL. THE EXTENT OF BLOWING SNOW
WILL DEPEND ON TOTAL ACCUMULATIONS...BUT EXPECT ANY LOCATION WITH
MORE THAN 2 INCHES OF SNOW TO SEE QUITE A BIT OF BLOWING WITH SOME
DRIFTING...AND THOSE AREAS THAT SEE CLOSER TO 5 OR 6 INCHES OF
SNOW CAN EXPECT SOME PRETTY SUBSTANTIAL BLOWING AND DRIFTING. WITH
THE TREND TOWARD A SLIGHTLY LATER END TIME FOR THE SNOW...EXPECT
THE MORNING COMMUTE TO BE RATHER DIFFICULT.
THURSDAY NIGHT THROUGH MONDAY...
STILL EXPECT A RATHER BENIGN WEATHER PATTERN THROUGH THIS PERIOD
AND HAVE NOT MADE MANY CHANGES TO THE FORECAST GIVEN THE HIGH
IMPACT WEATHER PRESENT IN THE SHORT TERM. MADE SOME ADJUSTMENTS TO
THE TEMPERATURES BASED ON EXPECTED SNOW COVER AS BOTH HIGH AND LOW
TEMPS IN THE NORTHERN FORECAST AREA COULD BE QUITE A BIT COOLER
THAN THE MODEL CONSENSUS. FRIDAY MORNING...AND EVEN SATURDAY
MORNING...COULD BE QUITE COLD AS HIGH PRESSURE BUILDS INTO THE
AREA WITH LIGHT WINDS...CLEAR SKIES...AND SNOW COVER.
MONDAY NIGHT THROUGH WEDNESDAY...
THERE REMAINS PLENTY OF UNCERTAINTY REGARDING A POTENTIAL STORM
SYSTEM DURING THIS PERIOD NEAR OR JUST AFTER CHRISTMAS DAY. THE
OPERATIONAL ECMWF AND GFS HAVE COME BACK INTO AGREEMENT IN TERMS
OF PLACING THE FORECAST OFFICE ON THE COLD SIDE OF A POTENT STORM
SYSTEM. TIMING WOULD SUGGEST THAT THE BULK OF PRECIP POTENTIAL
WOULD COME ON THE NIGHT OF THE 25TH INTO THE 26TH. HAVE MAINTAINED
CHANCES FOR SNOW ACROSS THE AREA DURING THIS TIME FRAME AND WILL
CONTINUE TO MONITOR THE PROGRESSION OF THIS STORM SYSTEM. THE TAKE
AWAY POINT AT THIS TIME IS THAT THE POTENTIAL FOR ACCUMULATING
WINTER PRECIPITATION EXISTS...BUT IS BY NO MEANS A GUARANTEE AT
THIS TIME AS THE ENERGY IS CURRENTLY OVER EASTERN RUSSIA AND
SIGNIFICANT CHANGES TO THE FORECAST ARE POSSIBLE IN THE NEXT FEW
DAYS. STAY TUNED.
BARJENBRUCH
&&
.AVIATION...
STRONG WINTER STORM STILL EXPECTED TO IMPACT THE AVIATION SITES
OVER THE NEXT 24 HOURS. EXPECT SNOW TO BEGIN BETWEEN 05Z AND 07Z
AT THE TERMINALS AND PERSISTING THROUGH ARON 12Z. HEAVY SNOW
COULD ALSO FORM GENERALLY BETWEEN 09Z AND 12Z AND COULD CAUSE VIS
TO DROP CONSIDERABLY. ALSO EXPECT STRONG WINDS UP TO 40 KTS AT THE
TERMINALS...WHICH WILL CAUSE WHITE OUT CONDITIONS THROUGH AT LEAST
12Z. EXPECT CONDITIONS TO GRADUALLY IMPROVE AFTER 12Z WITH CIGS
GRADUALLY CLEARING OUT BETWEEN 15Z AND 18Z.
JL
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 9 AM CST THURSDAY
FOR KSZ011-012-024.
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM CST
THURSDAY FOR KSZ026-039-040-055-056-058-059.
WINTER STORM WARNING UNTIL 6 AM CST THURSDAY FOR KSZ008-009-020-
021-034.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM CST THURSDAY
FOR KSZ010-022-023.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
THURSDAY FOR KSZ035>038-054.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
353 PM EST WED DEC 19 2012
.SYNOPSIS...
HIGH PRESSURE WILL BRING DRY WEATHER TONIGHT INTO EARLY THURSDAY.
A STRONG COLD FRONT WILL MOVE ACRSS THE AREA THURSDAY AFTERNOON
AND EVENING BRINGING SHOWERS TO THE REGION. MUCH COLDER AIR WILL
MOVE IN BEHIND THE FRONT WITH SNOW SHOWERS AND GUSTY WINDS LATE
THURSDAY NIGHT THROUGH SATURDAY EVENING.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
RECENT SURFACE AND SATELLITE DATA SHOW THE CLOUDS CONTINUE TO
LINGER ACROSS THE UPPER OHIO VALLEY. DESPITE HIGH PRESSURE
SUBSIDENCE...RECENT RUC MODEL PROFILES SHOW LOW CLOUDS WILL BE SLOW
TO THIN BEFORE POSSIBLY DISSIPATING TONIGHT. WITH HIGHER CLOUDS FROM
INCOMING LOW PRESSURE SYSTEM ALSO BEGINNING TO SPREAD INTO THE
UPPER OHIO VALLEY TONIGHT...DECIDED TO MAINTAIN FORECAST OF MOSTLY
CLOUDY SKIES.
REGARDING TEMPERATURES..CONCUR WITH RECENT SURFACE DATA AND GFS AND
NAM MOS AND SREF MODEL OUTPUT THAT LOWS TONIGHT WILL BE MAINLY NO
LOWER THAN MID 30S.
SURFACE WINDS WILL BE LIGHT TONIGHT...BUT SOUTHEASTERLY WINDS
DEVELOPING NEAR DAWN CAN GUST TO 25 MPH DOWNSLOPE LOCATIONS WEST OF
THE APPALACHIAN MOUNTAINS.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
LOW PRESSURE WL TRACK NEWD TO THE GREAT LAKES RGN THU INTO FRI. A
COLD FRONT WL MOV E ACRS THE AREA LATE THURSDAY INTO THURSDAY EVE.
MOST OF THE MOISTURE IS PRE FRONTAL. EXPECT A BAND OF SHOWERS TO
MOVE THROUGH AHEAD OF THE FRONT. GUSTY WINDS OF 30-40 MPH ARE
EXPECTED. SHOULD BE JUST BELOW WIND ADVISORY CRITERIA BUT WL HAVE
TO MONITOR.
ATTENTION THEN TURNS TO COLD AIR MOVING IN BEHIND THE FRONT...AND
SNOW SHOWERS. WRAP AROUND MOISTURE BEHIND THE LOW WL BRING SNOW
SHOWERS TO THE ENTIRE AREA. THE HEAVIEST SNOW SHOULD BE LOCATED IN
THE HIGHER TERRAIN...WITH GOOD UPSLOPE FLOW AND OMEGA. KEPT WINTER
STORM WATCH AS IS IN THAT AREA...WITH MENTION OF NEAR BLIZZARD
CONDITIONS. WL MONITOR THIS SITUATION AS WELL TO SEE IF BLIZZARD
HEADLINES WOULD EVENTUALLY BE NEEDED. THE SECOND AREA OF HEAVIER
SNOW WL BE SE OF LAKE ERIE...WHERE LAKE ENHANCEMENT COMBINED WITH
THE WRAP AROUND SYNOPTIC MOISTURE SHOULD BRING DECENT SNOWFALL. NO
SGFNT CAPPING INVERSION EITHER WHICH SHOULD HELP BRING HEAVIER
SNOWFALL RATES. WENT WITH A WINTER STORM WATCH IN THIS AREA AS
WELL WITH THE POTENTIAL FOR HEAVY SNOW AND GUSTY WINDS. THIS
INCLUDES THE I 80 CORRIDOR. ELSEWHERE...EXPECT BELOW WARNING
CRITERIA SNOWFALL...ALTHOUGH ADVISORIES WL LIKELY BE NEEDED AS THE
EVENT NEARS. PCPN SHOULD BEGIN TO WIND DOWN SAT EVE AS DEEPER
MOISTURES MOVES OUT AND HIGH PRES TRIES TO NUDGE EWD.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
BLEND OF RECENT GFS AND ECMWF MODEL OUTPUT SHOWS HIGH PRESSURE
SHOULD PROMOTE MAINLY DRY SEASONABLY COLD CONDITIONS SUNDAY AND
MONDAY.
THERE CONTINUES TO BE UNCERTAINTY REGARDING THE WEATHER FOR
CHRISTMAS DAY AND WEDNESDAY AS GFS AND ECMWF DIFFER ON EVOLUTION
DETAILS OF INCOMING LOW PRESSURE SYSTEMS. AT THIS JUNCTURE DEFERRED
TO HPC SOLUTIONS WHICH SUPPORTED IDEA THAT THERE CAN BE
PRECIPITATION MOVING ACROSS THE UPPER OHIO VALLEY CHRISTMAS DAY AND
WEDNESDAY.
REGARDING TEMPERATURES...ALSO CONCURRED WITH HPC WITH PREFERENCE TO
COLDER ECMWF MOS...WHICH SHOWED LOWS AND HIGHS STRADDLING THE
FREEZING POINT. SO NOT SURPRISINGLY FORECAST FOR CHRISTMAS DAY AND
WEDNESDAY HAS A CHANCE OF RAIN AS WELL AS A CHANCE OF SNOW.
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
RECENT SURFACE AND SATELLITE DATA SHOW STRATUS LINGERING ACROSS THE
UPPER OHIO VALLEY INTO TONIGHT...DESPITE HIGH PRESSURE SUBSIDENCE
ALOFT.
REMAINING IFR STRATUS AND FOG NEAR THE KFKL AND KDUJ CAN LIFT TO
MVFR BY AFTER 21Z...ALTHOUGH CONCUR WITH GFS LAMP THAT NOCTURNAL
COOLING MAY PROMOTE A LOWERING OF CONDITIONS AT KDUJ TO IFR NEAR
KDUJ AROUND MIDNIGHT.
ELSEWHERE REMAINING MVFR STRATUS SHOULD LIFT TO VFR LEVELS EARLY
TONIGHT AND PERHAPS DISSIPATE LEAVING ALTOSTRATUS AND CIRROSTRATUS
CEILINGS.
SURFACE WINDS WILL BE LIGHT MOST OF TONIGHT...BUT DEVELOPING
SOUTHEASTERLY WINDS AHEAD OF INCOMING LOW PRESSURE SYSTEM CAN CAUSE
GUSTS TO 25 KTS AT LOCATIONS DOWNSLOPE OF THE APPALACHIAN MOUNTAINS
PARTICULARLY KDUJ KLBE AND KMGW.
AS LOW PRESSURE SYSTEM GETS CLOSER TO THE UPPER OHIO VALLEY DAYTIME
THURSDAY...VFR STRATOCUMULUS CEILINGS WILL DEVELOP AND MAY GO TO
MVFR WITH ONSET OF AFTERNOON RAIN SHOWERS.
MORE OF AN AVIATION CONCERN CAN BE THE SURFACE WINDS INCREASING IN
SPEED FROM THE SOUTHEAST WITH GUSTS TO 35 KTS POSSIBLE BY THURSDAY
EVENING.
.OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/...
PASSAGE OF STRONG LOW PRESSURE SYSTEM AND ITS COLD FRONT THURSDAY
EVENING WILL PROMOTE IFR RAIN SHOWERS AND WIND GUSTS TO 40 KTS.
ENSUING COLD WESTERLY WINDS WILL PROMOTE PERIODS OF IFR RESTRICTIONS
IN SNOW SHOWERS LATE THURSDAY NIGHT INTO SATURDAY AFTERNOON. SURFACE
WINDS CAN CONTINUE TO GUST AT TIMES OVER 35 KTS.
ENSUING HIGH PRESSURE SHOULD PROMOTE IMPROVEMENT TO VFR SUNDAY AND
MONDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH SATURDAY
EVENING FOR MDZ001.
OH...NONE.
PA...WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH SATURDAY
EVENING FOR PAZ007>009-015-016-074-076.
WV...WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH SATURDAY
EVENING FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1139 AM EST WED DEC 19 2012
.SYNOPSIS...
HIGH PRESSURE WILL MAINTAIN MAINLY DRY AND CLOUDY CONDITIONS INTO
TONIGHT. THEN A STRONG COLD FRONT WILL BRING RAIN SHOWERS THURSDAY
AFTERNOON...FOLLOWED BY WINDY AND MUCH COLDER CONDITIONS WITH SNOW
SHOWERS FRIDAY AND SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RECENT SURFACE AND SATELLITE DATA SHOW THE CLOUDS CONTINUE TO
LINGER ACROSS THE UPPER OHIO VALLEY. DESPITE HIGH PRESSURE
SUBSIDENCE...RECENT RUC MODEL PROFILES SHOW CLOUDS NOT THINNING
OUT...SO HAVE MAINTAINED MAINLY CLOUDY SKIES THIS AFTERNOON AND
TONIGHT.
PER RECENT SURFACE DATA...HAVE ADDED MENTION OF PATCHY DRIZZLE
ACROSS PARTS OF THE I-80 CORRIDOR INTO EARLY AFTERNOON.
REGARDING TEMPERATURES..CONCUR WITH RECENT SURFACE DATA AND RAP
NAM AND SREF MODEL OUTPUT THAT AFTERNOON HIGHS WILL BE AT MOST NO
MORE THAN 3 DEGREES WARMER THAN 11 AM REPORTS. LOWS TONIGHT WILL
BE MAINLY NO LOWER THAN MID 30S.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
WHILE SOLIDLY IN THE WARM SECTOR THURSDAY...A COUPLED UPPER JET STRUCTURE
MOVES THROUGH THE REGION ON THURSDAY EVENING...COINCIDENT WITH
THIS...STRONG FRONTOGENETICAL LIFT PROVIDES AMPLE ASCENT AHEAD OF
AN EASTWARD ADVANCING COLD FRONT TO ALLOW FOR CATEGORICAL 100
PERCENT POPS THROUGH THE LATTER HALF OF THURSDAY INTO THURSDAY
EVENING. THEN THE FUN BEGINS...
A FUNNY THING HAPPENS ON THE WAY TO OCCLUSION WITH THIS SYSTEM.
FAIRLY STRONG AGREEMENT EXISTS ON THE AREA ENDING UP IN THE LARGE
SCALE DRY SLOT ON THURSDAY NIGHT POST-FRONTAL AND POST CHANGEOVER.
GENERALLY...THIS WOULD BE THE END OF THE PROMISE OF A HEAVY WINTER
STORM SNOWFALL EVENT. HOWEVER...THIS TIME LOOKS TO BE A BIT
DIFFERENT.
THE LARGE SCALE SYSTEM ITSELF SEEMS TO REACH MATURITY OVER
NORTHERN ILLINOIS ON THURSDAY WITH A WELL-DEVELOPED TROWAL
AIRSTREAM CURVING CYCLONICALLY AND ASCENDING AROUND THE OCCLUDING
SYSTEM ITSELF. HOWEVER...EVEN WHILE THE SYSTEM FILLS...THE TROWAL
CONTINUES TO WRAP FARTHER AND FARTHER AROUND THE FIRST
NORTH...THEN NORTHWEST...THEN WEST...AND EVENTUALLY SOUTHWEST
PORTION OF THE SYSTEM. AS THIS OCCURS...WE ACTUALLY END UP WITH
SYNOPTIC LIFT AND RESATURATION OF THE DENDRITIC LAYER ACROSS A
WIDE SWATH OF THE FORECAST AREA ON FRIDAY. THIS OCCURS VIA A
COMBINATION OF ISENTROPIC ASCENT AS WELL AS WEAK FRONTOGENESIS ON
THE PERIPHERY OF THE TROWAL AIRSTREAM. ADDITIONALLY...BECAUSE THE
TROWAL REMNANT ON THE NAM/GFS CONSENSUS LIES ROUGHLY IN THE -6 TO
-14C LAYER...IT DOES MANAGE TO AT LEAST BISECT THE LOWER SECTION
OF THE DENDRITIC LAYER AT THAT TIME. THIS SHOULD LEAD TO A PERIOD
OF ACCUMULATING SNOW IN LOW LEVEL COLD ADVECTION FOR MOST OF THE
CWA ON FRIDAY.
WHILE THE TROWAL EVOLUTION AND WRAP UP OF THE LARGE SCALE SYSTEM
WILL MANAGE TO KEEP THE LOW LEVEL FLOW FROM GOING NORTHWESTERLY
TOO EARLY ON FRIDAY...ALL SIGNS POINT TO THAT HAPPENING IN A BIG
WAY LATER IN THE DAY. WITH SECONDARY COLD ADVECTION...LOW LEVEL
LAPSE RATES LOOK TO STEEPEN MARKEDLY AFTER 15Z FRIDAY. THIS WILL
QUICKLY BRING THE DENDRITIC LAYER LOWER AND ALLOW FOR LOW LEVEL
INSTABILITY TO WORK WITHIN THE DENDRITIC LAYER...INCREASING SNOW
RATIOS MARKEDLY. ADDITIONALLY...WHEN CONSIDERING LOW LEVEL FLOW OF
NEARLY 60 KTS AT ABOUT 3000 FEET...AND 850 MB COOLING TOWARD -10C
YIELDS A NEARLY PERFECT OVERLAY OF INSTABILITY AND OROGRAPHIC
ASCENT ALL WITHIN THE CRITICAL -12 TO -20C LAYER OF THE DENDRITIC
GROWTH ZONE. AS A RESULT...WHILE QPF VALUES RAMP UP TOWARD 0.25
INCHES PER 6 HOURS...RATIOS LOOK TO EASILY EXCEED 15:1
CONSERVATIVELY. THIS SEEMS QUITE LIKELY TO RESULT IN COPIOUS
SNOWFALL...EASILY IN EXCESS OF 6 INCHES FOR THE RIDGES. CURRENT
BUFKIT PROJECTIONS YIELD SNOW RATIOS OF UP TO 25:1 AT TIMES AND UP
TO A FOOT OF ACCUMULATION IN THE RIDGES. WHILE THIS EVENTUALITY
SEEMS QUITE LIKELY...ALL PUBLIC PRODUCTS WILL BE MAINTAINED WITH 6
INCHES OR MORE WORDING FOR CONSISTENCY UNTIL A FINAL WARNING
DECISION CAN BE MADE.
OUTSIDE THE RIDGES...THE LOW LEVEL FLOW EVOLUTION TO NORTHWEST
AFTER 18Z FRIDAY WILL LIKELY HAVE OVER RAMIFICATIONS. WITH
INVERSION HEIGHTS RISING TOWARD AND EVEN ABOVE 10 KFT FRIDAY
EVENING AND LAKE TO 850 MB DELTA T VALUES RUNNING AROUND 18C OR
SO...INSTABILITY IN THE LAYER GETS RATHER EXTREME. CONSIDERING
THAT THERE IS STILL SOME SYNOPTIC MOISTURE AVAILABLE AND LITTLE
LOW LEVEL DRY ADVECTION WITH STRONG LAPSE RATES IN THE
LAYER...LAKE EFFECT BANDS WILL BE LIKELY TO INCREASE LATE FRIDAY
INTO FRIDAY NIGHT DOWNWIND OF LAKE ERIE. ASSUMING FLOW GOES
NORTHWESTERLY ENOUGH...THESE WILL PROBABLY REQUIRE ADDITIONAL
WINTER HEADLINES FOR THE I-80 CORRIDOR...AS WELL AS POSSIBLY THE
SLIGHTLY HIGHER AREAS OF JEFFERSON AND INDIANA COUNTIES. AT THE
MOMENT...ACCUMULATIONS IN THESE AREAS ARE PROBABLY THE MOST
UNCERTAIN OF THE FORECAST. STAY TUNED TO FUTURE STATEMENTS AND
PRODUCTS FROM THE NATIONAL WEATHER SERVICE FOR ADDITIONAL
INFORMATION.
AND ONE MORE ISSUE TO DEAL WITH...WIND. UNDER COLD ADVECTION...GFS
BUFKIT SUGGESTS ABOUT 45-60 KTS AT THE TOP OF THE MIXED
LAYER...PARTICULARLY FRIDAY MORNING. SHOULD THIS EVENTUALITY COME
TO FRUITION AND EXTEND INTO FRIDAY WITH CONTINUALLY FALLING
SNOW...BLIZZARD CONDITIONS WOULD BE LIKELY IN THE RIDGES. THE
POSSIBILITY OF AN UPGRADE TO THE WINTER STORM WATCHES TO BLIZZARD
WATCHES IS REAL...HOWEVER AT THIS TIME...A STRONGLY WORDED WINTER
STORM WATCH WILL BE CONTINUED. FRIES
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
CONSENSUS OF RECENT GFS...CMC...ECMWF AND NAEFS MODEL OUTPUT SHOW
STRONG LOW PRESSURE SYSTEM EXITING NORTH OF LAKE ERIE FRIDAY
NIGHT...BUT PROVIDING STRONG COLD UNSTABLE LOW LEVEL FLOW ACROSS THE
UPPER OHIO VALLEY INTO SATURDAY. HENCE EXPECT BLUSTERY WESTERLY
WINDS FRIDAY NIGHT INTO SATURDAY...PERHAPS EXCEEDING 40 MPH ACROSS
THE MOUNTAINS...PLUS LAKE-EFFECT ORTHOGRAPHICALLY-ENHANCED SNOW
SHOWERS.
SO A WINTER STORM WATCH WILL BE CONTINUED FOR THE WV-MD MOUNTAINS
INTO SATURDAY.
ENSUING HIGH PRESSURE SHOULD PROMOTE MAINLY DRY SEASONABLY COLD
CONDITIONS SUNDAY AND MONDAY.
THERE IS UNCERTAINTY REGARDING THE WEATHER FOR CHRISTMAS. THE
ECMWF MODEL SHOWS A DEEP LOW PRESSURE SYSTEM MOVING NORTHEASTWARD
THROUGH MIDWEST AND SPREADING PRECIPITATION INTO THE UPPER OHIO
VALLEY. THE GFS...LIKE MOST NAEFS MEMBERS SHOW THE LOW STILL
DEVELOPING OVER THE SOUTHERN PLAINS WITH HIGH PRESSURE LINGERING
ACROSS THE NORTHEASTERN U.S.
SO AT THIS JUNCTURE HAVE CONTINUED DRY SEASONABLE CONDITIONS FOR
CHRISTMAS DAY.
SPECIFIC TEMPERATURES WERE FORECASTED USING A BLEND OF GFS AND ECMWF
MOS.
&&
.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
RECENT SURFACE AND SATELLITE DATA SHOW STRATUS LINGERING ACROSS
THE UPPER OHIO VALLEY THIS MIDDAY...DESPITE HIGH PRESSURE
SUBSIDENCE ALOFT.
REMAINING IFR STRATUS AND FOG NEAR THE MOUNTAINS SHOULD LIFT TO
MVFR BY 18Z-19Z. MVFR CEILINGS ELSEWHERE SHOULD LIFT TO VFR AFTER
19Z.
SURFACE WINDS WILL BE FROM THE WEST AND SOUTHWEST 5 TO 10 KTS
TODAY AND THEN BECOME LIGHT AND MORE EASTERLY TONIGHT.
.OUTLOOK.../THURSDAY THROUGH SUNDAY/...
A STRONG LOW PRESSURE SYSTEM WILL BRING RESTRICTIONS AND GUSTY
WINDS LATE THURSDAY AND FRIDAY. RESTRICTIONS WILL CONTINUE AS
RAIN CHANGES TO SNOW BEHIND THE SYSTEM AND NORTHWESTERLY FLOW
MAINTAINS LAKE ENHANCED SNOW SHOWER/STRATOCUMULUS THROUGH AT LEAST
SATURDAY. VFR CONDITIONS LOOK TO RETURN BY SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH SATURDAY
EVENING FOR MDZ001.
OH...NONE.
PA...WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH SATURDAY
EVENING FOR PAZ074-076.
WV...WINTER STORM WATCH FROM LATE THURSDAY NIGHT THROUGH SATURDAY
EVENING FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
344 PM CST WED DEC 19 2012
.SHORT TERM...TONIGHT THROUGH SATURDAY.
...BLIZZARD TO IMPACT MUCH OF EASTERN NEBRASKA/WESTERN IOWA...
OBVIOUS CONCERN/FOCUS IN THE SHORT TERM WILL BE THE DEVELOPING
BLIZZARD WHICH WILL AFFECT MOST OF THE SOUTHEAST 2/3RDS OR SO OF
THE FORECAST AREA TONIGHT.
AFTERNOON SATELLITE SHOWED DEEP UPPER TROUGH FROM WY THROUGH CO
WITH STRONG POTENTIAL VORTICITY MAX ALONG CO/NM BORDER. AS
THROUGH/PV MAX TRACK EAST TONIGHT...MID LEVEL FLOW FORECAST TO
CLOSE OFF JUST TO OUR SSE WITH RESULTANT FRONTOGENESIS PROVIDING
STRONG LIFT. ALTHOUGH A GOOD PART OF THIS LIFT IS IN DENDRITIC
LAYER...SOME OCCURS EARLY THIS EVENING BELOW THAT LEVEL.
HOWEVER...CROSS SECTIONS SHOWED FOLDING OF THETA SURFACES
INDICATING UPRIGHT OR AT LEAST SLANT-WISE CONVECTIVE BANDS
POSSIBLE AIDING IN 1+ INCH SNOW RATES. ALSO A FEW INSTANCES OF
LIGHTNING HAVE BEEN REPORTED BOTH W OF LNK AND NE OF OMAHA.
12Z GFS/NAM HAVE INCREASED QPF NOW IN 1 INCH RANGE ALONG I80 INTO
WRN IA...ALTHOUGH ECMWF WAS LESS. USING A BLEND WOULD STILL
PROVIDE A BAND OF 7-9+ INCHES OF SNOW IN THE 00Z-12Z PERIOD USING
SNOW TO LIQUID RATIOS OF 13 TO 1 WEST TO AROUND 10-1 EAST THIS
EVENING AND 14-1 OR SO AFTER 06Z...USED A BIT LOWER RATIOS ACROSS
FAR SE. FORECAST SOUNDINGS INDICATED A RAIN/SLEET MIX POSSIBLE TO
BEGIN EVENT FAR SERN ZONES THROUGH 03Z. LATEST RAP FORECAST
SOUNDINGS ALSO FORECAST 65-75 KT WINDS SEVERAL K FEET ABOVE THE
SURFACE SPREADING FM FNB-FBY WITH SPEEDS AT THAT LEVEL IN 55-65KT
RANGE AT LNK/OMA TAPERING TO 45-50 AT KOFK. THUS DYNAMIC MIXING OF
SOME THESE WINDS DOWN TONIGHT SHOULD PROVIDE GUSTS THAT COULD
EXCEED 45-50KTS... ESPECIALLY SERN ZONES.
BLOWING/DRIFTING SNOW SHOULD LINGER THURSDAY MORNING ALTHOUGH HOW
WIDESPREAD BLIZZARD VISIBILITIES ARE MAINTAINED IS A QUESTION.
NONETHELESS...FELT RISK WAS GREAT ENOUGH WITH INITIAL LATE MORNING
ISSUANCE TO KEEP ERN 2/3RDS OR SO OF BLIZZARD AREA VALID THROUGH
18Z...AND THIS WAS CONTINUED IN AFTERNOON PACKAGE. SOME BLOWING
SNOW COULD LINGER ACROSS FAR ERN ZONES AFTER 18Z BUT WOULD EXPECT
VSBYS IMPROVING ENOUGH SO NO HEADLINE PAST THAT TIME. NO OTHER
WEATHER EXPECTED IN SHORT TERM WITH CLEARING AFTERNOON SKIES
LIKELY LASTING THROUGH SATURDAY.
LITTLE CHANGES TO TONIGHTS LOWS BUT WOULD EXPECT WITH FRESH SNOW
COVER MUCH OF THE AREA RECOVERY WILL BE TOUGH AND THUS REDUCED
DIURNAL RANGE. FRESH SNOW AND LIGHT WINDS SHOULD ALLOW MANY TEMPS
TO BE ON OR BELOW THE COLD SIDE OF GUIDANCE THU NGT/FRIDAY.
ALTHOUGH CONTINUED WARM ADVECTION COULD KEEP READINGS UP FRI NGT
AND ALLOW A BIT MORE RECOVERY SATURDAY...KEPT TEMPS NEAR COOLER
MAV MANY AREAS.
CHERMOK
&&
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
A WEAK COLD FRONT MOVES THROUGH SATURDAY NIGHT WITH HIGH PRESSURE
BUILDING IN FOR SUNDAY AND SUNDAY NIGHT. SURFACE LOW PRESSURE OVER
THE ROCKIES MONDAY CONTINUES TO ORGANIZE AND DEVELOP OVER THE
SOUTHERN PLAINS. A MID LEVEL WAVE MOVES THROUGH THE PLAINS MONDAY
NIGHT THROUGH TUESDAY NIGHT. WITHIN THE LONG WAVE...THERE IS SOME
STRONGER ENERGY OVER THE NORTHERN PLAINS. SINCE THE FORECAST AREA IS
WELL AWAY FROM THE ENERGY IN THE NORTH AND THE MAIN STORM SYSTEM TO
OUR SOUTH...WE HAVE A CHANCE FOR LIGHT SNOW AND FLURRIES WITH THE
WAVE. THE TEMPERATURES ARE VERY COLD ALOFT...SO IT SHOULD BE EASY
TO GET LIGHT SNOW AND FLURRIES...THUS THERE MAY BE SOME LIGHT
ACCUMULATIONS. AT THIS TIME THE ORGANIZED PRECIPITATION IS ACROSS
KANSAS AND MISSOURI OVER THE CHRISTMAS HOLIDAY.
TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE EXTENDED.
ZAPOTOCNY
&&
.AVIATION...
18Z TAFS FOR KOFK...KLNK AND KOMA.
HAZARDOUS WEATHER EXPECTED AT ALL TERMINALS THROUGH TONIGHT. SFC
LOW PRES CURRENTLY SITUATED NEAR WRN KS WILL LIFT NEWD AND PUSH
INTO NRN MO BY 12Z THURSDAY. THIS STORM SYSTEM WILL BE THE FOCUS
FOR BLIZZARD CONDITIONS DEVELOPING OVER MOST OF ERN NEB TONIGHT.
AT THIS POINT...EXPECT SN TO REACH TAF SITES BY EARLY EVENING WITH
CONDITIONS RAPIDLY DETERIORATING TO LIFR/+SN BLSN AND DRIFTING SN
PREVAILING THRU ABOUT 12Z THURSDAY MORNING. SNOWFALL ACCUMULATIONS
SHOULD GENERALLY RANGE FROM ABOUT 6 TO 11 INCHES BY EVENTS END
MID MORNING THURSDAY. HOWEVER...NW WINDS GUSTING AROUND 30KT WILL
MAINTAIN BLSN CONDITIONS UP THRU 18Z THURSDAY.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...BLIZZARD WARNING FROM 6 PM THIS EVENING TO NOON CST THURSDAY FOR
NEZ015-090>093.
BLIZZARD WARNING UNTIL 6 AM CST THURSDAY FOR NEZ050-065-078-088-
089.
BLIZZARD WARNING UNTIL NOON CST THURSDAY FOR NEZ033-034-044-045-
051>053-066>068.
WINTER STORM WARNING UNTIL 6 AM CST THURSDAY FOR NEZ032-042-043.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR NEZ016-
030.
WINTER WEATHER ADVISORY UNTIL 6 AM CST THURSDAY FOR NEZ017-018-
031.
IA...BLIZZARD WARNING FROM 6 PM THIS EVENING TO NOON CST THURSDAY FOR
IAZ043-055-056-069-079-080-090-091.
&&
$$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1251 PM EST WED DEC 19 2012
.SYNOPSIS...
A BREAK IN THE WEATHER CAN BE EXPECTED THROUGH TONIGHT AS HIGH
PRESSURE BUILDS ACROSS THE REGION. FAIR AND CHILLY WEATHER WILL
LAST INTO THURSDAY. THEN A STRONG STORM SYSTEM WILL SPREAD LIGHT
TO MODERATE RAIN ACROSS THE AREA THURSDAY NIGHT INTO FRIDAY
MORNING. COLDER AIR ON THE BACK SIDE OF THIS SYSTEM WILL CHANGE
RAIN SHOWERS TO SNOW DURING THE DAY FRIDAY...WITH ACCUMULATING
SNOW SHOWERS FOR MUCH OF THE AREA FRIDAY NIGHT INTO THE
WEEKEND...ESPECIALLY FOR CENTRAL NEW YORK.
&&
.NEAR TERM /THROUGH TONIGHT/...
1000 AM UPDATE...LASTEST RAP MODEL SHOWS A NORTHWEST FLOW OF AIR
FROM THE SFC THRU THE MID TROPOSPHERE BEHIND THE DEPARTING CYCLONE
OFF THE NEW ENGLAND COAST. THERE REALLY WASN`T THAT MUCH COLD AIR
UNDER AN INVERSION WHICH WAS FORECAST TO RISE TO ARND 850 MB BY
AFTERNOON AS PER LATEST RAP BUFKIT SOUNDING DATA...THEN DROP OFF
TOWARD EVENING AS SUBSDC KICKS WITH AN APPRACHING RDG WHICH
EXTENDS FROM THE SFC THTU 500 MB. THUS WE REALLY DON/T SEE ANY
PRECIP WITH LES WITH 850 MB TEMPS ARND -6 TO -7C WHICH GIVES VERY
MARGINAL 13-14C DIFFERENTIALS. THE LATEST SPORT SST/S SHOW LAKE
ONTARIO ARND 7-8C. SO I CAN SEE SC COMING DOWN OFF THE LAKE IN
ADDTN TO MORE SC DEVELOPING WITH SOME INSOLATION THIS AFTERNOON.
TEMPERATURES WILL RISE JUST A DEGREES AS THE DIURNAL TREND IS
FIGHTING CAA. SO MAINLY A PS TO MC AFTERNOON WITH CHILLY BUT
SLIGHTLY ABOVE NORMAL TEMPERATURES.
FOR TONIGHT...RDG BUILDS IN FROM THE SFC THRU 500 MB AND SKIES
SHUD TRY TO CLEAR OUT. THERE STILL WILL BE SOME FLOW OFF LAKE
ONTARIO SO SOME LAKE CLOUDS LIKELY WILL BE ARND MUCH OF THE NGT SO
WON/T GO COMPLETELY CLR. THIS WILL KEEP MINS FROM DROPPING BELOW
THE 20S WHICH IS ABOVE NORMAL AS WELL.
700AM UPDATE...
A WEAK SHORTWAVE ADVANCED FROM NE OH INTO CENTRAL PA AND FELL
APART...SO THE REMAINS OF LIGHT PRECIPITATION IS ALMOST ENTIRELY
DEPENDENT ON LAKE MOISTURE THIS MORNING. 925MB TEMPERATURES HAVE
DIPPED SLIGHTLY BELOW ZERO...BUT SATURATED LAYER IS ALSO SHALLOW
TO WHERE ICE CRYSTAL INTRODUCTION IS A CHALLENGE. THERE IS ONLY
ABOUT 12-13 DEG CELSIUS DELTA-T BETWEEN LAKE TEMPERATURE AND
850MB...JUST BARELY ENOUGH FOR A LAKE RESPONSE /AND IN THIS
CASE...MAINLY CLOUDS AND NOT MUCH PRECIP/. THE FEW SPRINKLES AND
PERHAPS FLURRIES NORTH OF A SYRACUSE-NORWICH-DELHI LINE WILL COME
TO AN END QUICKLY THIS MORNING. WHERE THERE IS CLOUD
COVER...TEMPERATURES ARE STILL ABOVE FREEZING EARLY THIS MORNING.
OTHER THAN THE ABOVE DETAILS...WE ARE LOOKING AT A QUIET PERIOD
TODAY THROUGH TONIGHT. LAKE MOISTURE TRAPPED UNDER DEVELOPING
SUBSIDENCE INVERSION FROM INBOUND HIGH PRESSURE WILL MAKE
STRATOCUMULUS A BIT STUBBORN TO BREAK TODAY IN THE NORTHEASTERN
ZONES...BUT THERE HAS ALREADY BEEN SOME SUCCESS ELSEWHERE WHICH
WILL ALLOW SOME SUNSHINE TO MIX IN TODAY. HIGHS IN UPPER 30S TO
LOW 40S...EXCEPT LOW TO MID 30S AT HIGHEST ELEVATIONS.
EVENTUALLY WE CLEAR OUT THIS EVENING...ONLY TO HAVE HIGH CLOUDS
BEGIN TO SPREAD IN VERY LATE TONIGHT FROM THE SOUTHWEST. WENT ON
LOW SIDE OF GUIDANCE FOR MINIMUM TEMPERATURES TONIGHT /MAINLY LOW
TO MID 20S/ AS THERE SHOULD BE A PRETTY GOOD MOSTLY CLEAR WINDOW
FOR RADIATIONAL COOLING BEFORE THE INCREASING HIGH CLOUDS THURSDAY
MORNING.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
445 AM UPDATE...
I HAVE BEEN ABLE TO FURTHER CONTINUE TO TREND OF LATER ARRIVAL OF
PRECIPITATION WITH NEXT INBOUND SYSTEM...TO POINT THAT OTHER THAN
SLIGHT CHANCE IN WESTERN ZONES...ALL RAINFALL SHOULD BE WAIT UNTIL
AFTER DARK THURSDAY. CLOUDS WILL THICKEN THROUGH THE DAY
HOWEVER...VERY MUCH LIMITING AMOUNT OF HEATING AT THE SURFACE. IN
FACT...SURFACE HIGH OVER NEW ENGLAND JUXTAPOSED WITH THE DEEPENING
LOW IN THE GREAT LAKES...WILL ALLOW COLD AIR DAMMING TO SET UP
AGAINST THE CATSKILLS AND POCONOS INTO THURSDAY NIGHT. SOLID BATCH
OF RAIN /RANGING FROM THREE-QUARTERS OF AN INCH TO AN INCH-
AND-A-THIRD/ COMES THROUGH THURSDAY NIGHT THROUGH FRIDAY
MORNING...BUT DUE TO COLD AIR DAMMING WE WILL HAVE TO WATCH THE
EDGES OF NORTHEASTERN ZONES FOR POTENTIAL OF TEMPERATURE DROPPING
TO NEAR FREEZING AS THE RAIN COMES THROUGH...THUS AT LEAST A
CHANCE OF FREEZING RAIN/SLEET FOR A TIME THERE.
AS FOR CHANGEOVER OF RAIN TO SNOW...MODELS SUGGEST A DELAYED
ARRIVAL OF THE NECESSARY COLD AIR ADVECTION TO SUPPORT CHANGEOVER
/THOUGH NAM IS QUITE A BIT COLDER THAN THE OTHER MODELS AND MIGHT
SUPPORT EARLIER/. THOUGH MINOR WET SNOW ACCUMULATIONS MAY BEGIN
LATE THURSDAY NIGHT INTO FRIDAY MORNING AT HIGHER ELEVATIONS...BEST
AREAWIDE SNOW ACCUMULATION POTENTIAL WILL BE FRIDAY AFTERNOON INTO
PARTICULARLY FRIDAY NIGHT /AND BEYOND/...ESPECIALLY CENTRAL NEW
YORK. MOST OF AREA WILL ENTER THE DRY SLOT OF THE SYSTEM DURING
THE MIDDLE OF THE DAY FRIDAY...FURTHER PUTTING FOCUS MORE INTO LATE
FRIDAY THROUGH FRIDAY NIGHT FOR SNOW ACCUMULATIONS...WHEN DEEPER
MOISTURE OF THE LARGE COMMA HEAD OF THE SYSTEM MOVES BACK OVER THE
REGION.
WE HAVE CONTINUED MENTION OF ACCUMULATING SNOW IN THE
HAZARDOUS WEATHER OUTLOOK /MAINLY CENTRAL NEW YORK/...AND AT
THIS POINT AT LEAST ADVISORY LEVEL SNOW LOOKS QUITE
POSSIBLE...PARTICULARLY FINGER LAKES THROUGH MOHAWK VALLEY/TUG
HILL REGIONS. STAY TUNED FOR FORECAST UPDATES AS THIS EVENT GETS
CLOSER.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AN ACTIVE PTRN APPEARS TO BE SHAPING UP IN THE MED RNG. INITIAL
AREA OF LOW PRES WILL BE MOVG INTO THE CANADIAN MARITIMES SAT
NGT/SUN...WITH NW FLOW AND LES CONTINUING ON SAT NGT...THEN
DIMINISHING LATER ON SUN NGT. TIMING DIFFS W/RESPECT TO THE NXT
SYSTEM FCST TO APRCH EARLY NXT WEEK. FOLLOWED HPC HERE...HOLDING
OFF ON PCPN TIL NXT TUE NGT. INITIAL LOOK AT PROFILES SUGGEST A
WINTERY MIX...FAVORING MORE IN THE WAY OF SNOW OR FZRA AS OPPOSED
TO RAIN. INDICATED A GENERIC WINTERY MIX ATTM. NO SIGS CHGS TO HPC
GDNC OTHER THAN MINOR TWEEKS.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AREAS OF MVFR ACRS THE FCST AREA DUE TO CIGS...AND XPCT THIS TO
CONTINUE INTO THE EVNG HRS WITH NW FLOW PERSISTING. LATER TNGT AS
NW FLOW WEAKENS AND GRADUALLY BCMS NRLY THEN NELY...XPCT AREAS OF
MVFR TO DIMINISH. BY TMRW MRNG...A BKN-OVC CI DECK IS FCST TO MOV
INTO THE AREA IN ADVANCE OF THE NXT STORM SYSTEM. WINDS THIS AFTN
NW 10-20 KTS DIMINISHING TO 5 KTS OR LESS TNGT...BECMG ERLY ON
THURSDAY 5-10 KTS.
OUTLOOK...
THU NGT...IFR/MVFR IN MIXED PCPN OR RAIN/CIGS/BR.
FRI/FRI NGT/SAT...MVFR/IFR -SHSN.
SAT NGT/SUN...MVFR CNTRL NY IN CIGS/-SHSN. VFR NE PA.
MON...PATCHY MVFR CNTRL NY DUE TO CIGS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...DJN
NEAR TERM...DJN/MDP
SHORT TERM...MDP
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
331 PM EST WED DEC 19 2012
.SYNOPSIS...
A POTENT AND DEEP LOW PRESSURE SYSTEM WILL MOVE QUICKLY FROM
OKLAHOMA THIS EVENING INTO SOUTHERN LOWER MICHIGAN BY THURSDAY
NIGHT. THIS SYSTEM WILL BRING A POTPOURRI OVER WEATHER TO OHIO
VALLEY...INCLUDING A BAND OF MODERATE RAIN SHOWERS AND A FEW
THUNDERSTORMS WITH GUSTY WINDS ON THURSDAY...FOLLOWED BY A STRONG
COLD FRONT AND RAPID TEMPERATURE DROP LATE THURSDAY AFTERNOON AND
EVENING...WITH A CONTINUED INCREASE IN STRONG WIND GUSTS THURSDAY
NIGHT AND LINGERING INTO MUCH OF FRIDAY. IN ADDITION...SNOW AND
SNOW SHOWERS WILL WRAP THROUGH INDIANA AND OHIO WITH LIGHT
ACCUMULATIONS...AND WHEN COMBINED WITH THE PLUNGING
TEMPERATURES...STRONG WINDS...AND REDUCED VISIBILITIES...TRAVEL
CONDITIONS ARE EXPECTED TO DETERIORATE THURSDAY NIGHT AND INTO
FRIDAY. WINDS WILL DECREASE AND SNOW SHOWERS WILL END FRIDAY
NIGHT...WITH A QUIET PERIOD IN STORE FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THIS IS A QUIET PERIOD FOR THE WFO ILN FORECAST AREA...AS WEAK
HIGH PRESSURE YIELDS TO THE DEEPENING STORM IN THE SOUTHERN
PLAINS. BKN-OVC CIRRUS SHIELD WILL CONTINUE TO THICKEN OVERNIGHT
WHILE LIGHT/VARIABLE FLOW UNDER THE WEAK RIDGE AXIS TURNS EASTERLY
AND SLOWLY INCREASES THROUGH THE NIGHT IN RESPONSE TO THE
APPROACHING STORM. THIS SHOULD KEEP TEMPS A TICK ABOVE
GUIDANCE...BUT DID LOWER THE TEMPS FROM THE PREVIOUS FORECAST A
FEW DEGREES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
ALL THE FOCUS TODAY IS ON THE RAPIDLY DEEPENING LOW PRESSURE AND
ITS IMPACT ON THE FORECAST AREA ON THURSDAY AND FRIDAY. INHERITED
A FORECAST FROM PREVIOUS SHIFTS THAT ALREADY HAD MUCH OF THE GIST
OF WHAT WILL UNFOLD - THUS WE FOCUSED ON ADDING DETAIL WHERE WE
COULD AND GET HEADLINE DECISIONS MADE. THERE ARE NO SIGNIFICANT
CHANGES IN THE FORECAST ITSELF BASED ON TODAY/S DATA.
GOES WATER VAPOR IMAGERY AND 19.12Z RAOBS CLEARLY SHOW THE POTENT
SHORTWAVE TROUGH ABOUT TO INDUCE RAPIDLY DEEPENING SURFACE CYCLONE
OVER THE SRN PLAINS. KFGZ/KABQ RAOBS BOTH HAD MORE THAN 100M
HEIGHT FALLS /500MB/ WHILE AIRCRAFT SOUTH OF THESE STATIONS
SAMPLED AN INTENSE 150-170KT JET STREAK /250MB/ THAT SEEMS TO HAVE
BEEN UNDER-INITIALIZED BY ALL DETERMINISTIC MODEL SOLNS BY A GOOD
20KTS. A CLASSIC MID-WINTER SYSTEM...SATELLITE PRESENTATION IS
ALREADY IMPRESSIVE AND RAP ANALYSIS /19Z/ ALREADY HAS THE
TROPOPAUSE FOLD /1.5 PV SURFACE/ DOWN TO 650MB OVER NRN NM. 996MB
CYCLONE IS ALREADY DEEPENING IN THE OKLAHOMA PANHANDLE AND
GUIDANCE IS NOW TIGHTLY CLUSTERED IN A VERY TYPICAL DECEMBER TRACK
THROUGH MISSOURI AND OVER THE CHICAGO METRO AREA TOWARD DETROIT BY
LATE THURSDAY NIGHT...WITH BLIZZARD CONDITIONS TO THE LEFT OF THE
TRACK AND AMPLE CONVECTION/WINDS IN THE WARM SECTOR.
IT IS IMPORTANT TO NOTE THAT FOR THE WFO ILN CWA...THERE CONTINUES
TO BE A LESSENING MODEL SIGNAL FOR A DAMAGING /HIGH WIND WARNING/ WIND
EVENT. DPROG/DT OVER ABOUT THE LAST DAYS WORTH OF DAY HAS TRENDED
TO AN EARLIER DEEPENING...AND HIGHER MINIMUM PRESSURE WHEN THE LOW
TRACKS ACROSS SOUTHERN MICHIGAN...WITH LATEST DATA SUGGESTING
MODEST FILLING WILL BE OCCURRING THURSDAY NIGHT WITH PRESSURES
BOTTOMING OUT NEAR 984MB NEAR CHICAGO. THIS MODEST CHANGE
DECREASES TO SOME DEGREE THE ISALLOBARIC COMPONENT...AND HAS
ALLOWED THE 925MB/850MB LAYERED WIND MAX TO DROP OUT OF ALARMING
RANGE THAT WOULD HAVE OTHERWISE PROMPTED A HIGH WIND WATCH OR
WARNING. THAT BEING SAID...WE TAKE FROM THE WIND...BUT NOW HAVE
ADDED A LITTLE MORE SNOW BASED ON NOW-AGREED-UPON SECONDARY PV
ANOMALY THAT WILL WRAP SOUTHEAST THROUGH THE BASE OF THE UPPER
TROUGH LATER ON THURSDAY NIGHT...THAT SHOULD BRING A RATHER
CONCENTRATED PERIOD OF LIGHT SNOW/SNOW SHOWERS TO AREAS NORTH OF
I-70 THURSDAY NIGHT INTO FRIDAY. SO IMPACTS WILL STILL BE
SIGNIFICANT WITH THIS SYSTEM...PROBABLY MORE SO FROM ICY
ROADS/WINTER TRAVEL ISSUES THAN FROM WIND DAMAGE/POWER
OUTAGES...ALTHOUGH WITH ANTICIPATED GUSTS TO 45-50MPH OR A LITTLE
HIGHER...ISOLATED POWER OUTAGES AND MINOR/NUISANCE TREE DAMAGE IS
STILL EXPECTED.
DETAILS ON IT ALL...WITH THE TIGHT CLUSTERING OF THE NWP MODEL
SUITE CONFIDENCE IS HIGH IN MOST ASPECTS OF THIS FORECAST. VERY
STRONG/DEEP LAYERED FORCING IMMEDIATELY DOWNSTREAM OF THE PV
CURRENTLY IN NM WILL INDUCE A VERY STRONG MOISTURE TRANSPORT FEED
LATER TONIGHT WHICH WILL MANIFEST AS A ELONGATED/LARGE AREA OF
SHOWERS AND EMBEDDED THUNDERSTORMS RAPIDLY MOVING FROM MS VALLEY
INTO THE OHIO VALLEY LATE. THINK THIS SPREADS ACROSS THE WESTERN
AREAS JUST AFTER SUNRISE WITH BEST POTENTIAL OF THUNDER WEST OF
I-71 WHERE MUCAPE IS THE HIGHEST. ALL AREAS GET A GOOD 1/2 INCH OF
RAIN IT APPEARS WITH THIS ACTIVITY WHICH SHIFTS QUICKLY THROUGH
THE FORECAST AREA BY MID AFTERNOON.
A 60-65KT SOUTHERLY LOW LEVEL JET WILL BE DRIVING THIS
ACTIVITY...AND MAY PRESENT A WIND ISSUE AT THE SURFACE...BUT WARM
ADVECTION WIND EVENTS TOUGH TO REALIZE GIVEN INVERTED THERMAL
PROFILES...DEEP LAYERED OMEGA...AND THICK CLOUDS...SO THINK
MORNING/AFTN WILL BE WINDY...BUT NOT WIND ADVISORY
LEVELS...PROBABLY 20/25 GUST 35/40 MPH. PERHAPS A LITTLE STRONGER
IN HEAVIER REFLECTIVITY CORES WITH PASSING SHOWERS...BUT WE CHOSE
TO HOLD OFF ON A WIND ADVISORY FOR THE DAYLIGHT HOURS.
WIND POTENTIAL GOES UP MARKEDLY AS THE COLD FRONT PLOWS INTO
WESTERN AREAS AROUND 21Z AND MARCHES ACROSS THE CWA EFFECTIVELY IN
ABOUT 4-5 HOURS TIME. THERE IS LOW CONFIDENCE IN A FINE LINE OF
SHOWERS ALONG THIS BOUNDARY - AND IF IT OCCURS - THERE IS SHALLOW
SB BUOYANCY /SHOWN VERY NICELY IN 19.12Z BUFR SOUNDINGS FROM NAM-
WRF/ THAT THIS LINE COULD PRODUCE BRIEF HIGH WIND GUSTS.
HOWEVER...BUOYANCY IS SO SHALLOW THAT CHARGE SEPARATION SEEMS
IMPOSSIBLE AND THUNDER WILL BE A STRETCH...SO DECIDED TO GET WIND
ADVISORY GOING AT 21Z ALL AREAS IN CASE THE FRONT CAN TRANSPORT
STRONG GUSTS TO THE SURFACE VIA THIS MECHANISM. IN THE WAKE OF THE
FRONT...LAPSE RATES STEEPEN VERY QUICKLY AND WITH A PSEUDO-DRY
SLOT /THOUGH LOW LEVEL MOISTURE WILL STILL BE AMPLE/...THERE IS
REMAINING INSTABILITY WITH STRONG GUST POTENTIAL IN THE HOURS
FOLLOWING THE FRONT DESPITE DEEPER LAYER STRONG WINDS WILL HAVE
YET TO ARRIVE. WIND POTENTIAL CONTINUES INTO THE OVERNIGHT AS
19.12Z NAM/GFS/ARW-WRF ALL BRING 55-60KT 925-850MB LAYERED WIND
MAX SOUTHEAST FROM THE BACKSIDE OF THE LOW RIGHT THROUGH THE HEART
OF THE CWA. WITH COLD ADVECTION...RAPID PRESSURE RISES...AND
STEEPENING LAPSE RATES...CONTINUED ADVISORY LEVEL WINDS AND GUSTS
ARE EXPECTED AREA-WIDE. THE MOST CONCERNING AREA FOR HIGHER END
GUSTS CONTINUES TO BE ACROSS WEST-CENTRAL OHIO IN THE HIGHER
TERRAIN AREAS AND WEST TO THE INDIANA BORDER WHERE SOME 55 MPH
GUSTS COULD BE SEEN. ANOTHER BIG CHANGE FROM YESTERDAY IS THE
LINGERING OF STRONG WINDS NOW INTO THE AFTERNOON HOURS ON
FRIDAY...AND WHILE AMPLE LOW LEVEL MOISTURE AND OMEGA IS SEEN NEAR
THE SURFACE WHICH WILL HELP TEMPER GUSTS...EVEN CONSERVATIVE MOMENTUM
TRANSPORT /MIXING/ TECHNIQUES SUGGEST LOW-END WIND ADVISORY WINDS
WILL BE POSSIBLE MOST AREAS AT LEAST INTO THE MID AFTERNOON...AND
PARTICULARLY NORTH OF THE OHIO RIVER.
IN TERMS OF SNOW...THE TEMP DROP IN THE WAKE OF THE COLD FRONT IS
FAST AND IMPRESSIVE...AND MAY INDUCE RAPID ROAD FREEZING AND ICING
EVEN IN THE DRY SLOT EARLY THURSDAY EVENING. LATER IN THE
EVENING...SECONDARY PV WRAPS SOUTHEASTWARD /ACCOMPANIED BY LOW
LEVEL WIND MAX MENTIONED ABOVE/ AND SPREADS GOOD FORCING FOR UVM
INTO AREAS NORTH OF I-70 WHERE SNOW/SNOW SHOWERS WILL BE ABUNDANT.
SEE A NICE LITTLE STRIPE OF 1-2 INCHES OF SNOW ACROSS WCNTL INTO
CNTL OH...SO DECIDED TO BE SIMPLE AND COMBINE THE THREATS OF
STRONG WINDS/SNOW/REDUCED VISIBILITIES/ICY ROADS INTO A WINTER
WEATHER ADVISORY. SNOW AMOUNTS WON/T BE SIGNIFICANT...BUT COMING
OUT OF A LONG TERM WARM PERIOD...PAVEMENT SUBSURFACES ARE
ATYPICALLY WARM. WITH VERY COLD AIR AND PERSISTENT SNOW
SHOWERS/STRONG WINDS REMOVING THIS WARMTH FROM THE SKIN SURFACE OF
THE PAVEMENT...SETUP IS SUCH THAT ROADS COULD BECOME EXTREMELY
SLIPPERY IN THE WINTER WX ADVISORY AREA ESP LATER THURS NIGHT INTO
MUCH OF FRIDAY WHERE SNOW IS PERSISTENT. COMBINED WITH RAPID VSBY
CHANGES IN SNOW SHOWERS...THESE SITUATIONS CAN BE SNEAKY-
DANGEROUS...ESPECIALLY CONSIDERING THE MILD WINTER THUS FAR. DON/T
SEE A SIGNAL IN THE DATA FOR SNOW RATIOS AS DIFFERENT THAN CLIM0 -
MUCH OF LIFT/SATURATIONS REMAINS BELOW THE DENDRITIC GROWTH ZONES
AND COBB RATIOS FROM A WEALTH OF SOURCES ARE ALL FROM 8:1 TO 11:1
FOR MOST OF THE PERIOD. LOWEST CONFIDENCE IN WINTER WX ADVISORY
CONDITIONS IN AROUND CMH METRO...BUT DIDN/T WANT TO GET CUTE AT
THIS MOMENT AND TRY TO BE TOO FINE GIVEN INHERENT UNCERTAINTIES.
ISSUED THE WIND ADVISORY FOR AREAS IN THE SOUTH NOT EXPECTED TO
SEE SIGNIFICANT ENOUGH SNOW FOR TRAVEL ISSUES...BUT EVEN IN THESE
AREAS CANNOT RULE OUT A PERIOD OF SLIPPERY TRAVEL AS MAIN WAVE
TRAVERSES THE AREA FRIDAY NIGHT INTO FRIDAY MORNING WITH THE
STRONG WINDS AND COLD TEMPS AND WARM ROAD SURFACES CAUSING
SLIPPERY TRAVEL. FUTURE SHIFTS MAY NEED TO CONSIDER EXPANSION OF
THE WINTER WEATHER ADVISORY IF SNOW SHOWERS ARE MORE WIDESPREAD OR
CONTAIN HEAVIER RATES THAN CURRENTLY ANTICIPATED.
CONDITIONS RAPIDLY IMPROVE FRIDAY EVENING AS WINDS DECREASE AND
SYSTEM PULLS OUT.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
THE LONG TERM WILL START OFF WITH SOME LINGERING CLOUDS AND A
POSSIBLE FLURRY SATURDAY MORNING BEHIND THE DEPARTING STORM SYSTEM.
CLOUDS SHOULD BE OUT OF THE AREA BY SATURDAY NIGHT AS HIGH PRESSURE
EXTENDS ACROSS THE AREA. WENT BELOW THE MODEL CONSENSUS FOR FORECAST
HIGHS ON SATURDAY ACROSS THE NORTH WHERE CLOUDS AND REMNANT SNOW
COVER WILL KEEP TEMPERATURES DOWN. WENT BELOW THE MODEL CONSENSUS
FOR THE WHOLE AREA SATURDAY NIGHT WITH HIGH PRESSURE AND DECREASING
WINDS HELPING TO PRODUCE FAVORABLE CONDITIONS FOR RADIATIONAL
COOLING.
SUNDAY WILL BE A TRANSITION DAY AS THE HIGH SHIFTS EAST OF THE AREA
AND WEAK LOW PRESSURE APPROACHES FROM THE WEST. ON SUNDAY
NIGHT...CLOUD COVER WILL INCREASE AHEAD OF THIS WEAK LOW AS MOISTURE
GETS DRAWN NORTHWARD INTO THE OHIO VALLEY. MODELS ARE IN FAIR
AGREEMENT ON BRINGING LIGHT PRECIPITATION TO THE FORECAST AREA
SOMETIME BETWEEN EARLY MONDAY MORNING AND EARLY MONDAY
AFTERNOON...DEPENDING ON WHICH MODEL YOU LOOK AT. THIS TIMING WILL
PROBABLY HELP TO DETERMINE PRECIPITATION TYPE. GFS HAS THE COLDEST
AND QUICKEST ARRIVAL OF PRECIPITATION...ALLOWING FOR A PARTIAL MIX
OF RAIN AND SNOW ACROSS MUCH OF THE AREA FOR THIS EVENT. THE
ECMWF/CANADIAN MODELS ARE TOO WARM ALOFT FOR ANY SNOW...HOWEVER
BRING LIGHT RAIN INTO THE AREA WHEN TEMPERATURES ARE NEAR FREEZING
AT THE SURFACE. THEREFORE...THIS PARTICULAR TIME PERIOD WILL NEED
ADJUSTING AS THE TIME DRAWS NEARER. REGARDLESS IT DOES APPEAR THAT
QPF AMOUNTS WILL BE LIGHT FOR THIS LOW WITH NO ACCUMULATION OF ANY
SNOW EXPECTED IF ANY MIX DOES OCCUR.
AFTER A FAIR WEATHER DAY ON CHRISTMAS...THE ATTENTION TURNS TO
CHRISTMAS NIGHT INTO WEDNESDAY AS A VIGOROUS LOW PRESSURE SYSTEM
APPROACHES OUR REGION. MODELS ARE STILL SHIFTING WITH TIMING AND
LOCATION FOR THIS LOW BETWEEN RUNS. HOWEVER...IT DOES APPEAR ONE WAY
OR ANOTHER THAT PRECIPITATION WILL OCCUR. BUMPED UP POPS TO 50
PERCENT. COULD HAVE GONE HIGHER FOR POPS IF THERE WERE NOT STILL
TIMING DIFFERENCES AMONGST THE MODELS.
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
SFC HIGH PRESSURE TO SLIDE ACRS THE OHIO VALLEY AS UPPER LEVEL
RIDGE BUILDS INTO THE REGION TODAY. LOW LEVEL CLOUDS AND MVFR
CONDITIONS WILL SLOWLY IMPROVE FROM THE SW TO NE ACRS THE TAF SITES
THRU THE AFTERNOON. VFR CONDITIONS ARE EXPECTED OVERNIGHT AS
MID/HI LEVEL MSTR SPILLS IN AHD OF THE NEXT SYSTEM. DEEP SFC LOW
PRESSURE TO LIFT NE FROM THE CENTRAL PLAINS TONIGHT INTO THE
MID MS VLY BY THURSDAY MORNING AND THEN INTO THE GREAT LAKES
BY THURSDAY EVENING. FAVORABLE ISENTROPIC LIFT DEVELOPS THURSDAY
MORNING AHD OF A STRONG COLD FRONT. WILL ALLOW PRECIPITATION TO
DEVELOP ON THURSDAY WITH CIGS EVENTUALLY COMING DOWN INTO MVFR CAT
AT 30 HOUR CVG TAF.
WINDS WILL BECOME VARIABLE THIS AFTN AND THEN SWING AROUND TO THE
EAST IN ADVANCE OF THE NEXT SYSTEM. THESE WINDS WILL START TO VEER
TO THE SE AND SOUTH AND STRENGTHEN LATE IN THE PERIOD. GUSTS
UP TO 30 KTS WILL BE POSSIBLE BY EARLY THURSDAY AFTN. THESE WINDS
WILL VEER SOUTHWEST AND INCREASE WITH THE PASSAGE OF A STRONG
COLD FRONT LATE THURSDAY AFTN AND EARLY EVENING WHEN WIND GUSTS
UP TO 45 KTS WILL BE POSSIBLE.
OUTLOOK...MVFR CEILINGS AND MVFR TO IFR VISIBILITIES LIKELY
THURSDAY AFTERNOON INTO FRIDAY MORNING WITH MVFR CEILINGS
POSSIBLY LINGERING INTO SATURDAY MORNING. WIND GUSTS FROM 35 TO
45 KT LIKELY THURSDAY AFTERNOON THROUGH FRIDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER WEATHER ADVISORY FROM 4 PM THURSDAY TO 4 PM EST FRIDAY
FOR OHZ026-034-035-042>046-051>056-060>062.
WIND ADVISORY FROM 4 PM THURSDAY TO 4 PM EST FRIDAY FOR
OHZ063>065-070>074-077>082-088.
KY...WIND ADVISORY FROM 4 PM THURSDAY TO 4 PM EST FRIDAY FOR
KYZ089>100.
IN...WINTER WEATHER ADVISORY FROM 4 PM THURSDAY TO 4 PM EST FRIDAY
FOR INZ050-058-059.
WIND ADVISORY FROM 4 PM THURSDAY TO 4 PM EST FRIDAY FOR INZ066-
073>075-080.
&&
$$
SYNOPSIS...BINAU
NEAR TERM...BINAU
SHORT TERM...BINAU
LONG TERM...LATTO
AVIATION...AR