Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/21/12
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 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 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 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 MOUNT HOLLY NJ
919 PM EST THU DEC 20 2012
.SYNOPSIS...
A POTENT AREA OF LOW PRESSURE WILL TRACK ACROSS THE GREAT LAKES AND
NORTHEAST TONIGHT AND FRIDAY, THEN ACROSS EASTERN CANADA DURING THE
WEEKEND. ITS ASSOCIATED STRONG COLD FRONT WILL SWEEP ACROSS OUR
REGION EARLY FRIDAY MORNING. A WEAK AREA OF HIGH PRESSURE THEN
BUILDS DOWN INTO OUR REGION LATE SUNDAY AND MONDAY. A WEAK LOW
PRESSURE SYSTEM MAY AFFECT OUR AREA MONDAY NIGHT INTO TUESDAY, WITH
THE POTENTIAL FOR A MUCH STRONGER STORM SET TO ARRIVE ON THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
STARTING IN THE POCONOS, WE ARE PLANNING ON LETTING THE ADVY
EXPIRE AT 11 PM. THE DRY AIR ALOFT HAS EVAP COOLED AND THE
FREEZING RAIN IN THE HIGHER TERRAIN HAS CHANGED TO SNOW. THE
NUMBER OF MESONET SITES BELOW FREEZING WHICH ONCE WAS AROUND 20 IS
DOWN TO 6. HRRR AND LATEST WRF-NMMB HAS EVERYONE ABOVE FREEZING BY
03Z. SOME SLIPPERY SPOTS WERE REPORTED IN THE HIGHER TERRAIN OF
MONROE COUNTY AND AROUND A QUARTER INCH OF SNOW IN PLACES.
NOW FOR THE OTHER WEATHER HAZARD, THE WIND. NOT AN EASY DECISION
BECAUSE THE SOUNDINGS ARE NEARLY ISOTHERMAL WITH POOR LAPSE RATES.
THE 00Z SOUNDINGS SUPPORTED A COMP BETWEEN THE WRF-NMMB AND GFS
FCST SPEEDS. SINCE THEN THE VWP LOOK OK AT KAKQ AND KLWX FOR THE
NEW WRF-NMMB 925MB WINDS, BUT THE MODEL IS RUNNING AROUND 5 TO
10 KTS TOO HOT AT 850MB. SO FAR THE MIXING OF STRONGER WINDS IN
THE CAROLINAS HAS BEEN SPORADIC. SO WHAT WE CAN GATHER THERE HAVE
NOT BEEN UPSIDE SURPRISES YET. THE OVERALL WIND FIELDS ARE
FORECAST THOUGH TO INTENSIFY FURTHER AS TIME GOES ON TONIGHT AND
THE MOMENTUM TRANSFER WINDS ON OCCASION ARE MIXING ADVY LEVEL WIND
GUSTS DOWN. THE MESOSCALE MODELS AND WE DONT KNOW IF THEY ARE THIS
GOOD ARE NOT FORECASTING A SINGLE NCFRB TOWARD MORNING. AFTER
COORD WITH OKX AND LOOKING AT THE 12/1/10 ANALOG THEY FOUND (WHICH
WAS AN ADVY TYPE EVENT CENTERED MAINLY IN THE ERN PART OF OUR
CWA), WE DECIDED TO ISSUE A WIND ADVY THAT COINCIDES CLOSEST WITH
THE 70KT OR GREATER ISOTACH ON THE LATEST WRF-NMMB. WE INCLUDED
ALL OF DELAWARE BAY BECAUSE OF THE SE FLOW. IF A NCFRB DOES FORM
NEAR THE JET MAX, THE ADVY MAY NEED TO BE UPGRADED OR EXPANDED.
RIGHT NOW CONFIDENCE IS TOO LOW TO ISSUE.
THE REST OF THE FCST WAS KEPT PRETTY MUCH AS IS, MOST OF THE
HEAVIEST PCPN IS EXPECTED TO FALL AFTER MIDNIGHT AND END RATHER
QUICKLY WITH THE CFP AROUND 12Z.
OTHER THAN SOME NUISANCE FLOODING, NO HYDRO ISSUES ARE EXPECTED.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
A THREAT OF RAIN SHOULD STILL EXIST FOR THE NORTHERN ZONES EARLY
TOMORROW MORNING. THEN WHEN THE UPPER LOW AND COLD POOL ALOFT MOVES
CLOSER, A SHOWER ANYWHERE CAN`T BE RULED OUT. TEMP PROFILES
SUGGEST SNOW SHOWERS FAR NORTH AND WEST.
TEMPS WILL HOLD STEADY OR FALL THROUGH THE 40S (30S NORTH AND WEST)
TOMORROW WITH WINDS GUSTING TO 30 OR 40 MPH.
LITTLE TO NO ACCUMULATION IS EXPECTED WHERE THE FLAKES FLY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
A RATHER ACTIVE PATTERN LOOKS TO CONTINUE. THE OVERALL SYNOPTIC FLOW
IS COMPRISED OF A DEEP TROUGH OVER THE EAST FRIDAY NIGHT AND
SATURDAY, THEN ADDITIONAL ENERGY PUSHING INTO THE WEST ALLOWS
DOWNSTREAM RIDGING TO KICK THE TROUGH INTO CANADA WHERE IT TENDS TO
BECOME ELONGATED WEST TO EAST. A PIECE OF ENERGY ROTATING AROUND
THIS MAY ALLOW FOR A SHORT WAVE TROUGH TO SLIDE ACROSS THE GREAT
LAKES INTO THE NORTHEAST AROUND TUESDAY. A MUCH MORE PRONOUNCED
UPPER-LEVEL TROUGH THEN LOOKS TO EJECT OUT OF THE FOUR CORNERS
REGION TUESDAY NIGHT INTO WEDNESDAY. THIS FEATURE ALONG WITH A
DEEPENING SURFACE LOW IS THEN FORECAST TO MOVE THROUGH THE EAST NEXT
THURSDAY. OVERALL, THE MODEL GUIDANCE CONTINUES TO SHOW VARIABILITY
WITH TIMING AND SPACING OF EMBEDDED INDIVIDUAL FEATURES HOWEVER
CONTINUED SUPPORT FOR AN ACTIVE PATTERN. THE THERMAL GRADIENTS AND
AMPLITUDE OF THE PATTERN MAY BE PLAYING A ROLE WITH THE MODEL
VARIABILITY. IT APPEARS THERE IS AN INCREASING SIGNAL FOR AN EAST
COAST STORM DURING ABOUT THE SECOND HALF OF NEXT WEEK. OF COURSE
THIS FAR OUT, THE DETAILS ARE MUCH LESS CERTAIN AND THEREFORE MUCH
LOWER CONFIDENCE IN THE FORECAST BEYOND TUESDAY ESPECIALLY.
FOR FRIDAY NIGHT AND SATURDAY...AN INTENSE STORM IS FORECAST TO BE
IN THE SOUTHEAST CANADA AND NEW ENGLAND AREAS DURING THIS TIME
FRAME. IT WILL BE DRIVEN BY A SHARP UPPER-LEVEL TROUGH WITH A SHOT
OF MUCH COLDER AIR ALONG WITH IT. A RATHER DEEP CYCLONIC FLOW REGIME
WILL BE OCCURRING WITH THE POTENTIAL FOR SOME WRAPAROUND SNOW
SHOWERS, AND THE LAKE EFFECT SNOW MACHINE SHOULD BE IN HIGH GEAR. AS
THE CAA CONTINUES, SHORT WAVE ENERGY ROTATING AROUND THE PARENT
UPPER-LEVEL TROUGH SHOULD HELP TO MAINTAIN SOME SNOW SHOWERS INTO
OUR NORTHWEST ZONES. SOME OF THE MODEL GUIDANCE SHOWING SIGNS OF
CHANNELIZED VORTICITY ORIENTATED NORTHWEST TO SOUTHEAST. IF DEEP
ENOUGH MOISTURE CAN BE MAINTAINED AND ENOUGH LIFT/INSTABILITY CAN
OCCUR WITHIN THE NORTHWEST FLOW, SOME LOCALIZED SNOW SQUALLS MAY
OCCUR ACROSS NORTHEASTERN PENNSYLVANIA AND NORTHWESTERN NEW JERSEY.
WE WOULD LIKE TO SEE BETTER ORGANIZATION OF THE CHANNELIZED
VORTICITY TO INCREASE CONFIDENCE REGARDING LAKE EFFECT STREAMERS
REMAINING INTACT THIS FAR SOUTHEAST FROM THE LAKES. FOR NOW, WE
CARRIED LOW LIKELY POPS ACROSS THE POCONOS AND TOWARD FAR NORTHWEST
NEW JERSEY, THEN POPS TAPER WITH A SOUTHEASTWARD EXTENT. BEYOND THE
SLIGHT CHC POPS, WE CARRIED SCATTERED FLURRIES DOWN TO THE
INTERSTATE 95 CORRIDOR. SOME PLACES PARTICULARLY IN THE POCONOS
COULD PICK UP AN INCH OR TWO OF SNOW. FARTHER SOUTHEAST, WHILE A FEW
HEAVIER SNOW SHOWERS MAY BE ABLE TO OCCUR, THE DOWNSLOPING FLOW MAY
PROVIDE ENOUGH EXTRA DRYING TO ERODE THESE. THIS IS OF LOWER
CONFIDENCE THEREFORE DID NOT BRING THE SNOW SHOWER MENTION EVEN
FARTHER SOUTHEAST AND WENT WITH FLURRIES.
ANOTHER FORECAST CONCERN IS THE STRONG WIND POTENTIAL. A RATHER
TIGHT PRESSURE GRADIENT IS FORECAST TO REMAIN ACROSS OUR ENTIRE. THE
CAA COMBINED WITH THE TIGHT PRESSURE GRADIENT SHOULD KEEP THE SURFACE
WINDS GOING FRIDAY NIGHT DESPITE LESSENING VERTICAL MIXING AT TIMES.
THE VERTICAL MIXING IS MUCH MORE PRONOUNCED SATURDAY AS THE AIRMASS
IS CHILLY, THE LOW-LEVEL LAPSE RATES STEEPEN SOME MORE AND THERE IS
PLENTY OF WIND NOT TO FAR ABOVE THE SURFACE. THE FORECAST SOUNDINGS
GET CLOSE TO 40 KNOTS POTENTIALLY MIXING DOWN TO THE SURFACE,
ALTHOUGH THE GFS IS MORE ROBUST WITH THIS AS IT SUGGESTS NEARLY
50 KNOTS MIXING DOWN TO THE SURFACE. THE 925 MB WINDS ARE NOT AS
STRONG ON THE ECMWF WITH AROUND 40 KNOTS FORECAST SATURDAY
ESPECIALLY ACROSS THE SOUTHERN HALF OF OUR CWA. WE THOUGHT ABOUT
GOING WITH A HIGH WIND WATCH WITH THE GREATER CHC ACROSS ABOUT THE
SOUTHERN HALF OF THE CWA, HOWEVER THIS IS NEARLY TWO DAYS OUT. IT
MAY END UP BEING A WIND ADVISORY TYPE EVENT THEREFORE WE DECIDED TO
HOLD OFF ON ANY HEADLINES ATTM. WE HOWEVER WILL CONTINUE A
MENTION IN THE HAZARDOUS WEATHER OUTLOOK. WE INCREASED THE WINDS
SOME /ESPECIALLY GUSTS/ FOR SATURDAY FROM CONTINUITY WITH GUSTS
GENERALLY IN THE 40-45 MPH RANGE. AS FOR HIGH AND LOW TEMPERATURES,
WE GENERALLY TOOK AN EVEN BLEND OF THE NAM/GFS MOS.
FOR SUNDAY AND MONDAY /CHRISTMAS EVE/...THE POTENT STORM IS FORECAST
TO MOVE UP THROUGH THE CANADIAN MARITIMES, HOWEVER A TIGHTENED
PRESSURE GRADIENT GENERALLY REMAINS IN PLACE. THE OVERALL FLOW
THOUGH WILL BE LESSENING, HOWEVER VERTICAL MIXING WILL PROVIDE
ENOUGH FOR A BRISK DAY ON SUNDAY. IT APPEARS THAT WITHIN THE
NORTHWESTERLY FLOW, A SHORT WAVE ROTATING AROUND THE PARENT STORM
MAY TOSS A SURFACE TROUGH OR COLD FRONT TOWARD OUR REGION. THE LAKE
EFFECT SNOW MACHINE SHOULD BE WINDING DOWN SUNDAY AS THE CAA WANES
SOME AND THE LOW-LEVEL FLOW MAY TURN MORE WESTERLY.
A SHORT WAVE TRAVERSING THE NORTHERN TIER CHRISTMAS EVE MAY ALLOW
FOR A SURFACE LOW REFLECTION TO RACE OUT AHEAD OF THE DEEPENING
TROUGH IN THE WEST. SOME MOISTURE RETURN AHEAD OF IT ALONG WITH WAA,
MAY RESULT IN AN AREA OF OVERRUNNING PRECIPITATION. THERE IS A
QUESTION REGARDING HOW DRY THE AIRMASS IS OVER OUR AREA AND THE
STRENGTH OF THE OVERALL LIFT. A LIGHT INTENSITY OF THE PRECIPITATION
MAY PLAY MORE OF A ROLE, WITH EVEN DEPENDING ON HOW THE BOUNDARY
LAYER BEHAVES. FOR NOW WE WILL FAVOR SLIGHT CHC POPS FOR A WEAK
OVERRUNNING POTENTIAL AND GO RAIN AND/OR SNOW.
FOR TUESDAY...THE AFOREMENTIONED FRONT RUNNER WEAKER SURFACE WAVE
SHOULD SCOOT OUT TO SEA EARLY TUESDAY AS THE SHORT WAVE TROUGH MAY
END UP DAMPENING OUT SOME. WHILE THERE COULD BE SOME RESIDUAL LIGHT
PRECIPITATION AROUND TO START TUESDAY, WE SIMPLY FAVORED SLIGHT CHC
POPS IN THE MORNING GIVEN LOWER CONFIDENCE ON TIMING AND OF ANY MORE
ORGANIZED LIFT.
FOR WEDNESDAY AND THURSDAY...THE PATTERN ONCE AGAIN STARTS TO REALLY
RAMP UP WEDNESDAY AS ENERGY FROM THE FOUR CORNERS REGION SLIDES
ACROSS THE PLAINS AND THEN THE TENNESSEE VALLEY. THERE IS ANOTHER
SYSTEM UP IN THE CANADIAN MARITIMES OVERALL, WHICH WOULD TEND TO
LEAD TO BLOCKING. THIS DEVELOPING PATTERN IS LOOKING MORE CONDUCIVE
FOR A COASTAL STORM TO OCCUR. IN THIS UPCOMING POTENTIAL, THE
INITIAL SURFACE LOW MAY TRACK UP THE OHIO VALLEY BUT THEN WEAKEN.
HIGH PRESSURE POSITIONED OVER EASTERN CANADA, IF IT CAN BE
MAINTAINED, MAY HELP TO WEDGE A COLDER LOW-LEVEL AIRMASS SOUTHWARD
ACROSS AT LEAST PORTIONS OF OUR AREA. THIS COLD AIR DAMMING SCENARIO
WOULD OPEN THE DOOR FOR SURFACE LOW REDEVELOPMENT NEAR THE VIRGINIA
COAST AS THE BAROCLINICITY TIGHTENS UP DUE TO THE THERMAL GRADIENT
INCREASING. THIS WOULD PROBABLY ALLOW FOR SOME WARMING ESPECIALLY
ALOFT UNTIL THE MAIN STORM GETS GOING OFF OR ALONG THE COAST.
THEREFORE, CLOUDS INCREASE WEDNESDAY AND WE WENT WITH 40-50 POPS FOR
NOW AS THE POTENTIAL IS THERE FORE A DECENT STORM. WE HELD OFF ON
GOING WITH LIKELY POPS DUE TO ENOUGH MODEL UNCERTAINTY REGARDING
TIMING AND ESPECIALLY THE DETAILS. WE WENT WITH RAIN AND/OR SNOW FOR
THE PRECIPITATION TYPE AS ANY OTHER FROZEN/FREEZING PRECIPITATION IS
MORE DEPENDENT ON THE ACTUAL THERMAL STRUCTURES.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THE 00Z TAFS CONTINUED THE DECENT INTO IFR AND LIFR AS THE
HEAVIER RAIN MOVES IN TONIGHT WITH THE LOWEST CONDITIONS AFTER
MIDNIGHT. WE ALSO CONTINUED THE MENTION OF LLWS. THE GRADIENT EAST
TO SOUTHEAST WIND ITSELF WILL ALSO INCREASE AND GUSTS TO AROUND 40
KTS ARE POSSIBLE AT TERMINALS AND AIRPORTS CLOSER TO THE OCEAN IN
NEW JERSEY AND DELAWARE.
THE COLD FRONT IS EXPECTED TO MOVE THROUGH FROM SOUTHWEST TO
NORTHEAST ACROSS OUR CWA WITH PASSAGE TIME PLUS OR MINUS OF 12Z
BY A COUPLE OF HOURS. RAPID IMPROVEMENT TO MVFR IF NOT VFR
CONDITIONS IS THEN FORECAST. WINDS THOUGH WILL REMAIN BLUSTERY,
BUT THIS TIME FROM THE WEST. CIGS SHOULD IMPROVE TO VFR BY LATE IN
THE MORNING. WINDS WILL REMAIN BRISK THROUGH THE DAY. PEAK GUSTS
OF AROUND 30 KTS ARE LIKELY.
OUTLOOK...
FRIDAY NIGHT AND SATURDAY...MAINLY VFR. WEST-NORTHWEST WINDS
SUSTAINED 15-25 KNOTS WITH GUSTS TO AROUND 35 KNOTS. THE STRONGER
WINDS SHOULD OCCUR DURING THE DAY SATURDAY. THERE COULD BE SOME
SUB-VFR CONDITIONS IN LOCAL/BRIEF SNOW SHOWERS ESPECIALLY FROM THE
KABE AND KRDG TERMINALS NORTH AND WEST.
SUNDAY...VFR WITH NORTHWESTERLY WINDS MAINLY 10-20 KNOTS.
MONDAY AND TUESDAY...VFR MONDAY ALTHOUGH CLOUDS SHOULD INCREASE AND
LOWER SOME. A WEAKER SYSTEM MAY MOVE THROUGH MONDAY NIGHT INTO
TUESDAY WITH THE CHANCE OF SOME LIGHT PRECIPITATION. LIGHT WINDS
MONDAY BECOME NORTHERLY NEAR 10 KNOTS TUESDAY.
&&
.MARINE...
A STRONG COLD FRONT WILL TRACK ACROSS OUR REGION EARLY TOMORROW
MORNING. GALES REMAIN IN PLACE FROM 700 PM TONIGHT, THROUGH THE
SHORT TERM PERIOD, AND INTO THE OUTLOOK PERIOD. SOUTHEAST WINDS
TONIGHT WILL BECOME SOUTHWEST TOMORROW. SEAS WILL RESPOND AND COULD
REACH DOUBLE DIGITS. RAIN OVERNIGHT TONIGHT WILL BECOME MOE SHOWERY
TOMORROW.
OUTLOOK...
A POTENT STORM IS FORECAST TO BE TO OUR NORTH FRIDAY NIGHT THROUGH
SATURDAY BEFORE SHIFTING INTO THE CANADIAN MARITIMES DURING THE
WEEKEND. A TIGHT PRESSURE GRADIENT IN COMBINATION WITH CAA WILL
ALLOW FOR STEEPER LOW-LEVEL LAPSE RATES AND EFFICIENT VERTICAL
MIXING. THE GFS 925 MB WINDS ARE MUCH STRONGER COMPARED TO THE NAM
AND ECMWF, HOWEVER ALL POINT TO GALE FORCE WINDS OCCURRING. THE GFS
WOULD SUGGEST A CHC FOR A PERIOD OF STORM FORCE GUSTS. WE ARE NOT
ALL THAT CONFIDENT REGARDING STORMS, THEREFORE WE WILL CONTINUE WITH
THE GALE WARNING THROUGH THE DAY SATURDAY. THE WINDS SHOULD START
DIMINISHING SATURDAY NIGHT, THEREFORE WE DECIDED NOT TO EXTEND THE
GALE WARNING ATTM. THERE SHOULD BE A PERIOD OF SMALL CRAFT ADVISORY
CONDITIONS FOLLOWING THE GALES INTO ABOUT SUNDAY. A WEAK SYSTEM MAY
THEN MOVE THROUGH MONDAY NIGHT INTO TUESDAY, HOWEVER THE WINDS AND
SEAS ARE ANTICIPATED TO BE BELOW ADVISORY CRITERIA.
&&
.TIDES/COASTAL FLOODING...
A COASTAL FLOOD ADVISORY HAS BEEN ISSUED FOR FRIDAY MORNING`S HIGH
TIDE ALONG ALL OUR COASTAL SECTIONS, INCLUDING THE TIDAL PORTION OF
THE DELAWARE RIVER, EXCLUDING CHESAPEAKE BAY. STRENGTHENING
SOUTHEAST FLOW WILL ALLOW WATER TO PILE UP ALONG THE COASTAL
SECTIONS WHERE CURRENT DEPARTURES ARE RUNNING AROUND +1.5 FEET ABOVE
ASTRONOMICAL...THIS IS WITHOUT A STRONGER SOUTHEASTERLY FETCH THAT
IS EXPECTED TO OCCUR TONIGHT.
SOME OF OUR NUMERICAL GUIDANCE IS SUGGESTING THE UPPER DELAWARE BAY
AND LOWER DELAWARE RIVER COULD SEE SPOTTY LOW-END MODERATE COASTAL
FLOODING. THIS WILL HAVE TO BE CLOSELY WATCHED AND RE-EVALUATED
AFTER THIS EVENING`S HIGH TIDE...ANY ADDED FRESH WATER COULD
EXACERBATE THE ISSUE. WINDS ARE EXPECTED TO SHIFT TO THE WEST BY
LATE FRIDAY MORNING AND WILL HELP TO PUSH THE WATER OUT.
AS FOR THE CHESAPEAKE BAY, CURRENT DEPARTURES ARE A RUNNING LESS
THEN +1.0 FOOT. WITH THE HIGHER OF THE TWO HIGH TIDES OCCURRING LATE
FRIDAY MORNING INTO THE EARLY AFTERNOON HOURS THERE IS STILL TIME TO
ASSESS THE POTENTIAL FOR ANY COASTAL FLOODING. BASED ON OUR NEW
ADVISORY CRITERIA OF 3.8 FEET BOTH CAMBRIDGE AND TOLCHESTER BEACH
WOULD NEED AROUND A +2.5 FOOT DEPARTURE TO REACH THE MINOR
THRESHOLD.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...COASTAL FLOOD ADVISORY FROM 3 AM TO 11 AM EST FRIDAY FOR
PAZ070-071.
WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR
PAZ054-055.
NJ...WIND ADVISORY FROM 2 AM TO 9 AM EST FRIDAY FOR NJZ001-008-010-
012>014-016-020>027.
COASTAL FLOOD ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EST
FRIDAY FOR NJZ012>014-020-022>027.
COASTAL FLOOD ADVISORY FROM 3 AM TO 11 AM EST FRIDAY FOR
NJZ016>019-021.
DE...WIND ADVISORY FROM 2 AM TO 9 AM EST FRIDAY FOR DEZ001>004.
COASTAL FLOOD ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EST
FRIDAY FOR DEZ003-004.
COASTAL FLOOD ADVISORY FROM 3 AM TO 11 AM EST FRIDAY FOR
DEZ001-002.
MD...WIND ADVISORY FROM 2 AM TO 9 AM EST FRIDAY FOR MDZ015-019-020.
MARINE...GALE WARNING UNTIL 7 PM EST SATURDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI/KRUZDLO
SHORT TERM...KRUZDLO
LONG TERM...GORSE
AVIATION...GIGI/GORSE
MARINE...GORSE/KRUZDLO
TIDES/COASTAL FLOODING...HEAVENER
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
905 PM EST THU DEC 20 2012
.DISCUSSION...
LEADING EDGE OF THE APPROACHING SQUALL LINE WORKING ITS WAY INTO THE
NRN PENINSULA...SHOULD SEE PRECIP COMMENCE ACRS NRN LAKE/VOLUSIA
COUNTIES BEFORE MIDNIGHT THEN PUSH STEADILY SEWD THRU EARLY MORNING.
INDIVIDUAL CELLS WITHIN THE LINE ARE RATHER STRONG OVER THE GOMEX
BUT HAVE BEEN WEAKENING AS THEY MOVE ONSHORE OVER THE BIG BEND.
EVENING SOUNDINGS INDICATE A RAPIDLY CHANGING AIRMASS ASSOCD WITH
THE LINE...KMFL/KEYW SHOW A SHARP SUBSIDENCE INVERSION IN THE
H90-H80 LYR WITH PWAT VALUES ARND 0.9". KTBW SHOWS A WEAK INVERSION
IN THE H70-H60 LYR...A NEARLY SATURATED H100-H70 LYR...AND PWAT NEAR
1.5". KJAX NEARLY SATURATED SFC-CIG WITH PWAT NEAR 1.7".
SHORT TERM GUIDANCE MAINTAINS SUFFICIENT MOISTURE TO ALLOW THE
SQUALL LINE TO GENERATE PRECIP OVER MUCH OF THE CWA OVERNIGHT.
LATEST SAT/RADAR/CG LTG TRENDS INDICATE THE LINE DOES NOT HAVE THE
VERTICAL SUPPORT NECESSARY TO MAINTAIN DEEP CONVECTION ONCE THE
CELLS MOVE ONSHORE. RAP ANALYSIS CONFIRMS THIS AS UPR LVL DIVERGENCE
MAXIMUM HAS ALREADY MOVED OFF THE NE FL COAST WITH ASSOCD MID LVL
VORTICITY/OMEGA MAXES PREPARING TO DO SO AS WELL. LIMITING TSRA
ACTIVITY TO N BREVARD/NW OSCEOLA NWD LOOKS LIKE A GOOD CALL...ESP AS
THE COOLER NOCTURNAL ENVIRONMENT WILL MAKE IT DIFFICULT TO CARRY
DEEP CONVECTION TO THE TREASURE COAST AND LAKE OKEECHOBEE REGION.
STRONG CAA BEHIND THE FRONT WILL ALLOW TEMPS TO DROP RAPIDLY BEFORE
SUNRISE N OF I-4. MIN TEMPS IN THE M/U40S ACROSS NRN LAKE/VOLUSIA...
L50S ACRS METRO ORLANDO. READINGS ALONG THE SPACE AND TREASURE
COASTS SHOULD HOLD IN THE U50S/L60S AS THE DEEP COLD AIR IS NOT
EXPECTED TO PUSH THAT FAR S BEFORE DAYBREAK.
&&
.AVIATION...
N OF KISM-KTIX...THRU 21/08Z NMRS IFR SHRAS/SLGT CHC LIFR TSRAS WITH
LCL SFC W/SW WND G25-30KTS. BTWN 21/08Z-21/10Z...SHRAS/TSRAS ENDING
WITH SFC WNDSHFT TO W/NW...G25-30KTS CONTG THRU 21/18Z.
S OF KISM-KTIX...VFR THRU 21/05Z...CIGS DCRSG FM AOA FL120 TO BTWN
FL040-060. BTWN 21/05Z-21/11Z...SCT-NMRS MVFR SHRAS AND ISOLD IFR
+SHRAS...LCL SFC W/SW WND G25-30KTS. BTWN 21/10Z-21/12Z...
SHRAS/TSRAS ENDING WITH SFC WNDSHFT TO W/NW...G20-25KTS CONTG THRU
21/18Z.
&&
.MARINE...
WINDS HAVE KICKED UP TO 20-25KTS AT BUOY/012...SEAS STILL
LINGERING AT 4-6FT N OF CAPE CANAVERAL BUT EXPECT FULL BLOWN SCA
CONDITIONS BY MIDNIGHT. CONDITIONS S OF THE CAPE WILL DETERIORATE
STEADILY AS WELL...SHOULD SEE SCA WINDS AREAWIDE BY DAYBREAK AS THE
APPROACHING COLD FRONT PUSHES THRU CNTRL FL. GALE WARNING IN PLACE
FOR THE NRN OFFSHORE LEG...SCA ELSEWHERE...SET TO START AT 10PM. SET
UP LOOKS GOOD...COULD ARGUE FOR PUSHING THE START TIME UP AN HR BUT
OVERALL IMPACT WOULD BE NEGLIGIBLE. WINDS WILL SHIFT RAPIDLY TO THE
W/NW BEHIND THE FRONT...GALE/SCA STRENGTH CONTINUING WELL PAST
SUNRISE...SCA CONDITIONS AREAWIDE FRIDAY WITH BUILDING SEAS.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...RED FLAG WARNING FROM 11 AM TO 7 PM EST FRIDAY FOR COASTAL
VOLUSIA-INDIAN RIVER-INLAND VOLUSIA-MARTIN-NORTHERN BREVARD-
NORTHERN LAKE-OKEECHOBEE-ORANGE-OSCEOLA-SEMINOLE-SOUTHERN
BREVARD-SOUTHERN LAKE-ST. LUCIE.
AM...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 1 AM EST SUNDAY
FOR COASTAL WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD
COUNTY LINE OUT 20 NM-COASTAL WATERS FROM SEBASTIAN INLET
TO JUPITER INLET OUT 20 NM-COASTAL WATERS FROM VOLUSIA
BREVARD COUNTY LINE TO SEBASTIAN INLET OUT 20 NM-WATERS
FROM SEBASTIAN INLET TO JUPITER INLET 20 TO 60 NM OFFSHORE-
WATERS FROM VOLUSIA BREVARD COUNTY LINE TO SEBASTIAN INLET
20 TO 60 NM OFFSHORE.
SMALL CRAFT ADVISORY FROM 10 AM FRIDAY TO 1 AM EST SUNDAY FOR
WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE 20
TO 60 NM OFFSHORE.
GALE WARNING FROM 10 PM THIS EVENING TO 10 AM EST FRIDAY FOR
WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE 20
TO 60 NM OFFSHORE.
&&
$$
SHORT TERM...BRAGAW
LONG TERM....VOLKMER
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
714 PM EST THU DEC 20 2012
.AVIATION...
TEMPORARY VFR CONDS TO START THE PD WITHIN MID LVL DRYSLOT. HWVR
WIDESPREAD UPSTREAM IFR WEDGE WILL SPREAD QUICKLY EWD THROUGH LT
EVENING ALG W/ACCUMULATING SNOW AND ESCALATING GRADIENT WINDS.
SVRL HR PD OF LIFR CONDS IN MOD-HVY SNOW LIKELY TWD KSBN STARTING
TWD 03Z AS INTENSE MID LVL DEFORMATION BAND ACCENTUATED BY DVLPG LK
ENHANCEMENT SHIFTS EWD. ROLLED THIS FWD TO KFWA AT 13Z PER CONSENSUS
HIGHRES MODEL SIGNALS AS WELL. OTRWS SFC GUSTS TO 40KTS DVLPG TWD
DAYBREAK AND CONTG THROUGH FRI AM.
&&
.UPDATE...
MESOSCALE DVLPMNTS LT THIS AFTN IN COMBO W/MOST RECENT HIGHRES MODEL
GUIDANCE ALL POINTING TO SIG SNOW/WIND SPREADING EWD ACRS CWA
OVERNIGHT W/WIDESPREAD MOD-HVY SNOW NOTED OVR MUCH OF WRN/CNTRL IL. IN
FACT RECENT HRRR/RUC GUIDANCE INDICATING BRUTE WRAPPED UP MID LVL
CIRC NR KLAF HAS NOT YET PEAKED AND QUITE EVIDENT WITHIN
REINTENSIFYING DEFORMATION ZONE EXTENDING FM CNTRL IL NNE UP ACRS
WRN LK MI. IN FACT 21Z RUC DOES NOT BOTTOM H7 LOW UNTIL 12Z NR
WINDSOR ONTARIO. AS SUCH AND PER RAPID ESCALATION OF GRADIENT WINDS
WILL INITIALLY EXPAND WARNING SWD TO ENCOMPASS STARKE/MARSHALL AND
PLACE PULASKI/FULTON WITHIN HIGHER GRADED ADVISORY. FURTHER
EXPANSION OF WARNING PSBL FURTHER EAST BUT WILL CLOSELY
MONITOR CONTD EWD DVLPMNT/TRANSLATION OF DEFORMATION BAND AND
INCIPIENT LK ENHANCEMENT TWD 03-04Z ALG W/ADDNL 00Z BASED GUIDANCE
FOR CLUES.
&&
.PREV DISCUSSION... /ISSUED 404 PM EST THU DEC 20 2012/
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
LONGWAVE PATTERN HAS UNDERGONE TREMENDOUS AMPLIFICATION OVER THE
PAST 24 HOURS WITH POSITIVE FEEDBACK MECHANISMS FROM DEVELOPING
STORM PROMOTING STRONG RIDGING OVER THE EAST COAST. NOT TOO
SURPRISING THEN THAT THE LATEST 12Z GUIDANCE HAS TRENDED A TOUCH
FURTHER NORTHWEST WITH THE LOW TRACK...A SHIFT THAT HAS BEEN LARGELY
ANTICIPATED IN THE PAST FEW DISCUSSIONS AND REQUIRES LITTLE CHANGE
TO THE OVERALL FORECAST. LATEST SURFACE ANALYSIS SHOWS 983MB LOW
OVER CHICAGO AT PRESS TIME. LITTLE FURTHER DEEPENING IS EXPECTED AS
THE OCCLUSION PROCESS IS NOW UNDERWAY WITH A MATURE TROPOPAUSE FOLD
MOVING OVERHEAD LATER THIS EVENING. SURFACE LOW WILL CONTINUE TO
DRIFT NORTHEAST INTO LOWER MI DURING THE EVENING BEFORE CYCLONIC
SHEAR MAX PROPAGATES THROUGH THE BASE OF THE TROUGH AND FORCES
SECONDARY SURFACE LOW DEVELOPMENT OVER THE EAST COAST. MIDLEVEL DRY
SLOT HAS FILLED IN RATHER QUICKLY THIS AFTERNOON THANKS TO THE
IMPRESSIVE CVA ALOFT. EXPECT THIS TO CONTINUE AS THE LOW LEVEL
DEFORMATION AXIS PIVOTS INTO OUR CWA. TIMING OF TRANSITION TO SNOW
REMAINS A TOP CONCERN. SHARP RAIN/SNOW LINE IS CURRENTLY DRAPED OVER
CENTRAL IL WITH GOOD PUSH OF CAA FORCING A QUICK CHANGEOVER. SURFACE
WET BULBS LOOK TO REMAIN ABOVE FREEZING THROUGH ROUGHLY 03Z OVER
MOST OF OUR CWA. THIS MAY BE PARTIALLY OFFSET BY DYNAMIC COOLING
PROCESSES BUT EXPECT MOST AREAS WONT SEE ANY SNOW UNTIL ROUGHLY
01-02Z. THIS TRANSITION MAY TAKE EVEN LONGER OVER THE NORTHWEST WITH
CYCLONICALLY WRAPPED THERMAL TONGUE SLOW TO ERODE AND POSSIBLE
AIRMASS MODIFICATION NEAR THE LAKE.
STRONG WINDS WILL LIKELY BE THE BIGGEST STORY. IMPRESSIVE
ISALLOBARIC COMPONENT OVER THE REGION WILL WEAKEN SOMEWHAT AS THE
SURFACE LOW BEGINS TO FILL OVERNIGHT. HOWEVER...PROPAGATION OF THE
STILL VERY RESPECTABLE SURFACE LOW COMBINED WITH INCREASING CAA
PROMOTING DECENT LOW LEVEL INSTABILITY WILL SUPPORT STRONG WINDS.
925MB WINDS WILL BE APPROACHING 50 KTS BY TOMORROW MORNING AND THIS
SHOULD HAVE LITTLE DIFFICULTY MIXING TO THE SURFACE. EXPECT WIND
GUSTS UP TO 50 MPH LATE TONIGHT INTO TOMORROW MORNING...SUPPORTED BY
UPSTREAM OBS. IN FACT...ALREADY STARTING TO SEE SOME 40-45 MPH GUSTS
ALONG/BEHIND SURFACE BOUNDARY PASSING THROUGH THE AREA. CONTEMPLATED
GOING WITH HIGH WIND WARNING BUT HAVE ONLY SEEN A COUPLE 50+ KT
GUSTS UPSTREAM AND WHILE THIS MAY BE POSSIBLE NEAR THE
LAKESHORE...EXPECT MOST ARES TO STAY LARGELY BELOW WARNING CRITERIA.
QPF/SNOW FORECAST REMAINS TENUOUS. BEST LOW-MIDLEVEL DEFORMATION AND
ASSOCIATED FGEN RESPONSE CURRENTLY CAUSING HEAVY SNOW OVER NORTHERN
ILLINOIS AND SOUTHERN WISCONSIN WILL PASS LARGELY NORTHWEST OF OUR
AREA ALONG WITH THE TROWAL AXIS. THIS SYNOPTIC FORCING MAY CLIP OUR
NORTHWEST ZONES BUT SNOW AMOUNTS IN OUR CWA WILL BE HIGHLY DEPENDENT
ON DUBIOUS LAKE RESPONSE. PLENTY OF SYNOPTIC MOISTURE THROUGHOUT THE
COLUMN. INSTABILITY PARAMETERS ARE ALSO SUFFICIENT...AT LEAST BY
EARLY FRIDAY MORNING...WITH DELTA T`S IN THE MID TEENS AND
EQUILIBRIUM LEVELS CLIMBING TO AROUND 9 KFT BUT STRONG 850MB WINDS
REMAIN A CONCERN. NOT ONLY WILL THIS POTENTIALLY DISRUPT BAND
ORGANIZATION BUT THE MORE IMPORTANT IMPACT OF STRONG LOW LEVEL WINDS
MAY BE TREMENDOUS FRACTURING OF SNOWFLAKES...FORCING RELATIVELY LOW
SNOW RATIOS. NAM BUFR SOUNDINGS SUGGEST LAKE EFFECT SNOW WILL NOT
BEGIN IN EARNEST UNTIL AFTER 06Z TONIGHT WITH THE REAL COLD AIR PUSH
AND WILL TAPER OFF BY MIDDAY TOMORROW. QPF DURING THIS TIME LOOKS TO
BE AROUND 0.4 INCHES FOR OUR NORTHWEST COUNTIES. ASSUMING WE MANAGE
TO GET A 10:1 RATIO...THIS WILL RESULT IN MAINLY 3-5 INCHES WITH A
FEW ISOLATED HIGHER AMOUNTS. LAKE ENHANCED BANDS WILL LIKELY MAKE
FOR HIGHLY VARIABLE SNOW AMOUNTS...FURTHER EXACERBATED BY
DIFFICULTIES MEASURING SNOW IN HIGH WIND. AMOUNTS FURTHER DOWNSTREAM
WILL BE SLIGHTLY LOWER...THOUGH WITH THE VERY STRONG LOW LEVEL
FLOW...BANDS WILL LIKELY PENETRATE MUCH FURTHER INLAND THAN NORMAL.
HIGHEST SNOWFALL AMOUNTS MAY ACTUALLY END UP BEING FURTHER
DOWNSTREAM THAN THE IMMEDIATE LAKESHORE. NOT CONFIDENT ENOUGH TO
EXPAND WARNING BUT THIS IS SOMETHING THAT WILL NEED TO BE WATCHED.
STRONG WINDS WILL CERTAINLY CAUSE A FAIR AMOUNT OF BLOWING/DRIFTING.
AM A LITTLE CONCERNED THE MODEST SNOW AMOUNTS AND INITIALLY WARM
SURFACE TEMPS MAY LIMIT THE POSSIBILITY OF TRUE WHITEOUT CONDITIONS
BUT NEVERTHELESS EXPECT LARGE IMPACTS DURING THE MORNING COMMUTE AND
WILL MAINTAIN AREAWIDE WINTER WEATHER ADVISORY. SNOW AND HIGH WIND
WILL GRADUALLY TAPER OFF TOMORROW AFTERNOON AS LOW PRESSURE EXITS
THE REGION AND HIGH PRESSURE RETURNS WITH DRY AIR ADVECTION AND
SUBSIDENCE.
LONG TERM...
SATURDAY THROUGH THURSDAY...THE MAIN CHALLENGES THIS PERIOD ARE
DURING THE MIDDLE OF NEXT WEEK WHEN THERE IS THE POTENTIAL FOR
UNSETTLED WEATHER INCLUDING A CHANCE FOR MAINLY SNOW. FOR THIS
PACKAGE...OVERALL VERY POOR RUN TO RUN CONSISTENCY WITH MASS FIELDS
AMONG THE ECMWF AND GFS TENDING TO LOW CONFIDENCE IN THE FORECAST.
AT THIS POINT...FAVOR A GEM/CIPS ANALOG BLEND. THESE SOLUTIONS FAVOR
A MORE NORTHWEST TRACK OF THE SFC LOW...CLOSER TO THE UPPER LEVEL
SUPPORT. THE GFS IN THIS PATTERN TENDS TO INITIALLY TRACK THE SFC
LOW TOO FAR TO THE SOUTHEAST. THEREFORE...KEPT A HIGH CHANCE FOR
SNOW LATE WEDNESDAY INTO WEDNESDAY NIGHT. THERMAL PROFILES INDICATE
ALL SNOW DURING THIS PERIOD...SO WITH A MORE NORTHWEST TRACK AND
SUFFICIENTLY COLD TEMPERATURES ALOFT...FEEL THAT THERE IS A
REASONABLE CHANCE FOR ACCUMULATING SNOW. OTHERWISE...A WEAKER SYSTEM
WILL MOVE ACROSS THE AREA EARLY THIS WEEK WITH A CHANCE FOR A
RAIN/SNOW MIX MONDAY.
AVIATION...
18Z TAFS...DRY SLOT HAS NOW ENGULFED MOST OF THE AREA
ALTHOUGH SCATTERED SHOWERS ARE STILL BEING OBSERVED ALONG AND
AHEAD OF THE COLD FRONT LOCATED ALONG KLAF TO KIKK LINE. MAJOR
IMPACTS FOR THE REST OF THE DAY WILL BE STRONG SOUTHEASTERLY
WINDS. THESE WINDS WILL ABATE SLIGHTLY...ESPECIALLY AT KSBN...AS
THE LOW PRESSURE CENTER PASSES BY TO THE NORTHWEST. WINDS WILL
SHIFT FROM SOUTHEASTERLY TO SOUTHWESTERLY BEHIND THE FRONT...AND
EVENTUALLY NORTHWESTERLY LATER THIS EVENING AS PRECIPITATION
CHANGES OVER TO SNOW. THESE NORTHWESTERLY WINDS COULD GUST HIGHER
THAN 40 KNOTS BY FRIDAY MORNING. PRECIPITATION WILL CHANGE TO SNOW
BETWEEN 00Z AND 03Z TONIGHT. FALLING SNOW...COUPLED WITH STRONG
WINDS AND POTENTIAL FOR BLOWING SNOW WITH ANY ACCUMULATION THAT
MAY OCCUR WILL LIKELY RESULT IN SERIOUS VIS
RESTRICTIONS...ESPECIALLY BETWEEN 06Z AND 12Z TONIGHT.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR INZ006>009-013-
015>018-020-022>027-032>034.
WINTER STORM WARNING UNTIL 7 PM EST /6 PM CST/ FRIDAY FOR
INZ003>005-012-014.
MI...WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ079>081.
WINTER STORM WARNING UNTIL 7 PM EST FRIDAY FOR MIZ077-078.
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR OHZ001-002-004-
005-015-016-024-025.
LM...STORM WARNING FROM 10 PM THIS EVENING TO 5 PM EST FRIDAY FOR
LMZ043-046.
GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LMZ043-046.
&&
$$
SHORT TERM...DODSON
LONG TERM...SKIPPER
AVIATION...T
UPDATE...T
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
609 PM EST THU DEC 20 2012
.UPDATE...
MESOSCALE DVLPMNTS LT THIS AFTN IN COMBO W/MOST RECENT HIGHRES MODEL
GUIDANCE ALL POINTING TO SIG SNOW/WIND SPREADING EWD ACRS CWA
OVERNIGHT W/WIDESPREAD MOD-HVY SNOW NOTED OVR MUCH OF WRN/CNTRL IL. IN
FACT RECENT HRRR/RUC GUIDANCE INDICATING BRUTE WRAPPED UP MID LVL
CIRC NR KLAF HAS NOT YET PEAKED AND QUITE EVIDENT WITHIN
REINTENSIFYING DEFORMATION ZONE EXTENDING FM CNTRL IL NNE UP ACRS
WRN LK MI. IN FACT 21Z RUC DOES NOT BOTTOM H7 LOW UNTIL 12Z NR
WINDSOR ONTARIO. AS SUCH AND PER RAPID ESCALATION OF GRADIENT WINDS
WILL INITIALLY EXPAND WARNING SWD TO ENCOMPASS STARKE/MARSHALL AND
PLACE PULASKI/FULTON WITHIN HIGHER GRADED ADVISORY. FURTHER
EXPANSION OF WARNING PSBL FURTHER EAST BUT WILL CLOSELY
MONITOR CONTD EWD DVLPMNT/TRANSLATION OF DEFORMATION BAND AND
INCIPIENT LK ENHANCEMENT TWD 03-04Z ALG W/ADDNL 00Z BASED GUIDANCE
FOR CLUES.
&&
.PREV DISCUSSION... /ISSUED 404 PM EST THU DEC 20 2012/
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
LONGWAVE PATTERN HAS UNDERGONE TREMENDOUS AMPLIFICATION OVER THE
PAST 24 HOURS WITH POSITIVE FEEDBACK MECHANISMS FROM DEVELOPING
STORM PROMOTING STRONG RIDGING OVER THE EAST COAST. NOT TOO
SURPRISING THEN THAT THE LATEST 12Z GUIDANCE HAS TRENDED A TOUCH
FURTHER NORTHWEST WITH THE LOW TRACK...A SHIFT THAT HAS BEEN LARGELY
ANTICIPATED IN THE PAST FEW DISCUSSIONS AND REQUIRES LITTLE CHANGE
TO THE OVERALL FORECAST. LATEST SURFACE ANALYSIS SHOWS 983MB LOW
OVER CHICAGO AT PRESS TIME. LITTLE FURTHER DEEPENING IS EXPECTED AS
THE OCCLUSION PROCESS IS NOW UNDERWAY WITH A MATURE TROPOPAUSE FOLD
MOVING OVERHEAD LATER THIS EVENING. SURFACE LOW WILL CONTINUE TO
DRIFT NORTHEAST INTO LOWER MI DURING THE EVENING BEFORE CYCLONIC
SHEAR MAX PROPAGATES THROUGH THE BASE OF THE TROUGH AND FORCES
SECONDARY SURFACE LOW DEVELOPMENT OVER THE EAST COAST. MIDLEVEL DRY
SLOT HAS FILLED IN RATHER QUICKLY THIS AFTERNOON THANKS TO THE
IMPRESSIVE CVA ALOFT. EXPECT THIS TO CONTINUE AS THE LOW LEVEL
DEFORMATION AXIS PIVOTS INTO OUR CWA. TIMING OF TRANSITION TO SNOW
REMAINS A TOP CONCERN. SHARP RAIN/SNOW LINE IS CURRENTLY DRAPED OVER
CENTRAL IL WITH GOOD PUSH OF CAA FORCING A QUICK CHANGEOVER. SURFACE
WET BULBS LOOK TO REMAIN ABOVE FREEZING THROUGH ROUGHLY 03Z OVER
MOST OF OUR CWA. THIS MAY BE PARTIALLY OFFSET BY DYNAMIC COOLING
PROCESSES BUT EXPECT MOST AREAS WONT SEE ANY SNOW UNTIL ROUGHLY
01-02Z. THIS TRANSITION MAY TAKE EVEN LONGER OVER THE NORTHWEST WITH
CYCLONICALLY WRAPPED THERMAL TONGUE SLOW TO ERODE AND POSSIBLE
AIRMASS MODIFICATION NEAR THE LAKE.
STRONG WINDS WILL LIKELY BE THE BIGGEST STORY. IMPRESSIVE
ISALLOBARIC COMPONENT OVER THE REGION WILL WEAKEN SOMEWHAT AS THE
SURFACE LOW BEGINS TO FILL OVERNIGHT. HOWEVER...PROPAGATION OF THE
STILL VERY RESPECTABLE SURFACE LOW COMBINED WITH INCREASING CAA
PROMOTING DECENT LOW LEVEL INSTABILITY WILL SUPPORT STRONG WINDS.
925MB WINDS WILL BE APPROACHING 50 KTS BY TOMORROW MORNING AND THIS
SHOULD HAVE LITTLE DIFFICULTY MIXING TO THE SURFACE. EXPECT WIND
GUSTS UP TO 50 MPH LATE TONIGHT INTO TOMORROW MORNING...SUPPORTED BY
UPSTREAM OBS. IN FACT...ALREADY STARTING TO SEE SOME 40-45 MPH GUSTS
ALONG/BEHIND SURFACE BOUNDARY PASSING THROUGH THE AREA. CONTEMPLATED
GOING WITH HIGH WIND WARNING BUT HAVE ONLY SEEN A COUPLE 50+ KT
GUSTS UPSTREAM AND WHILE THIS MAY BE POSSIBLE NEAR THE
LAKESHORE...EXPECT MOST ARES TO STAY LARGELY BELOW WARNING CRITERIA.
QPF/SNOW FORECAST REMAINS TENUOUS. BEST LOW-MIDLEVEL DEFORMATION AND
ASSOCIATED FGEN RESPONSE CURRENTLY CAUSING HEAVY SNOW OVER NORTHERN
ILLINOIS AND SOUTHERN WISCONSIN WILL PASS LARGELY NORTHWEST OF OUR
AREA ALONG WITH THE TROWAL AXIS. THIS SYNOPTIC FORCING MAY CLIP OUR
NORTHWEST ZONES BUT SNOW AMOUNTS IN OUR CWA WILL BE HIGHLY DEPENDENT
ON DUBIOUS LAKE RESPONSE. PLENTY OF SYNOPTIC MOISTURE THROUGHOUT THE
COLUMN. INSTABILITY PARAMETERS ARE ALSO SUFFICIENT...AT LEAST BY
EARLY FRIDAY MORNING...WITH DELTA T`S IN THE MID TEENS AND
EQUILIBRIUM LEVELS CLIMBING TO AROUND 9 KFT BUT STRONG 850MB WINDS
REMAIN A CONCERN. NOT ONLY WILL THIS POTENTIALLY DISRUPT BAND
ORGANIZATION BUT THE MORE IMPORTANT IMPACT OF STRONG LOW LEVEL WINDS
MAY BE TREMENDOUS FRACTURING OF SNOWFLAKES...FORCING RELATIVELY LOW
SNOW RATIOS. NAM BUFR SOUNDINGS SUGGEST LAKE EFFECT SNOW WILL NOT
BEGIN IN EARNEST UNTIL AFTER 06Z TONIGHT WITH THE REAL COLD AIR PUSH
AND WILL TAPER OFF BY MIDDAY TOMORROW. QPF DURING THIS TIME LOOKS TO
BE AROUND 0.4 INCHES FOR OUR NORTHWEST COUNTIES. ASSUMING WE MANAGE
TO GET A 10:1 RATIO...THIS WILL RESULT IN MAINLY 3-5 INCHES WITH A
FEW ISOLATED HIGHER AMOUNTS. LAKE ENHANCED BANDS WILL LIKELY MAKE
FOR HIGHLY VARIABLE SNOW AMOUNTS...FURTHER EXACERBATED BY
DIFFICULTIES MEASURING SNOW IN HIGH WIND. AMOUNTS FURTHER DOWNSTREAM
WILL BE SLIGHTLY LOWER...THOUGH WITH THE VERY STRONG LOW LEVEL
FLOW...BANDS WILL LIKELY PENETRATE MUCH FURTHER INLAND THAN NORMAL.
HIGHEST SNOWFALL AMOUNTS MAY ACTUALLY END UP BEING FURTHER
DOWNSTREAM THAN THE IMMEDIATE LAKESHORE. NOT CONFIDENT ENOUGH TO
EXPAND WARNING BUT THIS IS SOMETHING THAT WILL NEED TO BE WATCHED.
STRONG WINDS WILL CERTAINLY CAUSE A FAIR AMOUNT OF BLOWING/DRIFTING.
AM A LITTLE CONCERNED THE MODEST SNOW AMOUNTS AND INITIALLY WARM
SURFACE TEMPS MAY LIMIT THE POSSIBILITY OF TRUE WHITEOUT CONDITIONS
BUT NEVERTHELESS EXPECT LARGE IMPACTS DURING THE MORNING COMMUTE AND
WILL MAINTAIN AREAWIDE WINTER WEATHER ADVISORY. SNOW AND HIGH WIND
WILL GRADUALLY TAPER OFF TOMORROW AFTERNOON AS LOW PRESSURE EXITS
THE REGION AND HIGH PRESSURE RETURNS WITH DRY AIR ADVECTION AND
SUBSIDENCE.
LONG TERM...
SATURDAY THROUGH THURSDAY...THE MAIN CHALLENGES THIS PERIOD ARE
DURING THE MIDDLE OF NEXT WEEK WHEN THERE IS THE POTENTIAL FOR
UNSETTLED WEATHER INCLUDING A CHANCE FOR MAINLY SNOW. FOR THIS
PACKAGE...OVERALL VERY POOR RUN TO RUN CONSISTENCY WITH MASS FIELDS
AMONG THE ECMWF AND GFS TENDING TO LOW CONFIDENCE IN THE FORECAST.
AT THIS POINT...FAVOR A GEM/CIPS ANALOG BLEND. THESE SOLUTIONS FAVOR
A MORE NORTHWEST TRACK OF THE SFC LOW...CLOSER TO THE UPPER LEVEL
SUPPORT. THE GFS IN THIS PATTERN TENDS TO INITIALLY TRACK THE SFC
LOW TOO FAR TO THE SOUTHEAST. THEREFORE...KEPT A HIGH CHANCE FOR
SNOW LATE WEDNESDAY INTO WEDNESDAY NIGHT. THERMAL PROFILES INDICATE
ALL SNOW DURING THIS PERIOD...SO WITH A MORE NORTHWEST TRACK AND
SUFFICIENTLY COLD TEMPERATURES ALOFT...FEEL THAT THERE IS A
REASONABLE CHANCE FOR ACCUMULATING SNOW. OTHERWISE...A WEAKER SYSTEM
WILL MOVE ACROSS THE AREA EARLY THIS WEEK WITH A CHANCE FOR A
RAIN/SNOW MIX MONDAY.
AVIATION...
18Z TAFS...DRY SLOT HAS NOW ENGULFED MOST OF THE AREA
ALTHOUGH SCATTERED SHOWERS ARE STILL BEING OBSERVED ALONG AND
AHEAD OF THE COLD FRONT LOCATED ALONG KLAF TO KIKK LINE. MAJOR
IMPACTS FOR THE REST OF THE DAY WILL BE STRONG SOUTHEASTERLY
WINDS. THESE WINDS WILL ABATE SLIGHTLY...ESPECIALLY AT KSBN...AS
THE LOW PRESSURE CENTER PASSES BY TO THE NORTHWEST. WINDS WILL
SHIFT FROM SOUTHEASTERLY TO SOUTHWESTERLY BEHIND THE FRONT...AND
EVENTUALLY NORTHWESTERLY LATER THIS EVENING AS PRECIPITATION
CHANGES OVER TO SNOW. THESE NORTHWESTERLY WINDS COULD GUST HIGHER
THAN 40 KNOTS BY FRIDAY MORNING. PRECIPITATION WILL CHANGE TO SNOW
BETWEEN 00Z AND 03Z TONIGHT. FALLING SNOW...COUPLED WITH STRONG
WINDS AND POTENTIAL FOR BLOWING SNOW WITH ANY ACCUMULATION THAT
MAY OCCUR WILL LIKELY RESULT IN SERIOUS VIS
RESTRICTIONS...ESPECIALLY BETWEEN 06Z AND 12Z TONIGHT.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR INZ006>009-013-
015>018-020-022>027-032>034.
WINTER STORM WARNING UNTIL 7 PM EST /6 PM CST/ FRIDAY FOR
INZ003>005-012-014.
MI...WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ079>081.
WINTER STORM WARNING UNTIL 7 PM EST FRIDAY FOR MIZ077-078.
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR OHZ001-002-004-
005-015-016-024-025.
LM...STORM WARNING FROM 10 PM THIS EVENING TO 5 PM EST FRIDAY FOR
LMZ043-046.
GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LMZ043-046.
&&
$$
SHORT TERM...DODSON
LONG TERM...SKIPPER
AVIATION...DODSON
UPDATE...T
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 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 GAYLORD MI
1059 PM EST THU DEC 20 2012
.SYNOPSIS...
ISSUED AT 414 PM EST THU DEC 20 2012
STRONG LOW PRESSURE OVER THE SOUTHERN GREAT LAKES...WILL CONTINUE TO
LIFT INTO SOUTHERN MICHIGAN...GENERATING CONTINUED WINTRY WEATHER
ACROSS NORTHERN MICHIGAN THROUGH FRIDAY. PERIODS OF HEAVY SNOW IS
EXPECTED FOR AREAS OF NORTHERN MICHIGAN THROUGH FRIDAY AFTERNOON.
ANY PRECIPITATION FALLING AS RAIN OR A RAIN....SNOW MIX WILL CHANGE
OVER TO SNOW THIS EVENING. WINDS WILL INCREASE TONIGHT AND CONTINUE
THROUGH FRIDAY.
&&
.UPDATE...
ISSUED AT 1053 PM EST THU DEC 20 2012
WOW...VERY IMPRESSIVE STORM UNFOLDING ACROSS THE REGION WITH
SURFACE LOW NEAR GLADWIN ATTM AND SLOWLY LIFTING NORTHEAST. OVER
THE LAST HOUR...HAVE NUMEROUS REPORTS OF THUNDER...3 INCHES OF
SNOW IN ONE HOUR AT PETOSKEY...AND EXPANDING POWER OUTAGES ACROSS
NORTHERN LOWER...NOT SURPRISING GIVEN THE HEAVY NATURE OF THE SNOW
ALONG WITH NUMEROUS REPORTS OF BRANCHES/TREES DOWN. EXPECT THAT WE
HAVE ANOTHER 2-4 HOURS BEFORE RATES BEGIN TO COME DOWN...WHICH
WILL LIKELY BRING TOTALS ABOVE 15" IN A FEW SPOTS /ESP OTSEGO
COUNTY/. RAIN/SNOW LINE IS STEADILY ADVANCING EAST /NOW SNOWING AT
PZQ/..AND WILL CONTINUE TO DO SO AS THE LOW PROGRESSES EAST.
LITTLE CHANGES NECESSARY TO THE GOING FORECAST...WITH SOME UPPED
SNOW TOTALS BASED ON EVENING OBSERVATIONS. WINDS WILL GET GOING
AFTER MIDNIGHT AS WELL...UNFORTUNATELY EXACERBATING AN ALREADY
HAZARDOUS SITUATION. IF YOU MUST BE OUT...USE EXTREME CAUTION!
UPDATE ISSUED AT 834 PM EST THU DEC 20 2012
LOOKING OUT THE WINDOW HERE AT APX REVEALS MODERATE TO HEAVY
SNOW...WITH RIMED DENDRITES SUGGESTING FAIRLY "WET" SNOW TO
LIQUID RATIOS /7-10:1/...IN AGREEMENT WITH EVENING OBSERVATIONS.
NOT SURPRISINGLY...CURRENT LIGHTNING DATA SHOWS SOME IN CLOUD
FLASHES OVER AND NEAR LITTLE TRAVERSE BAY...WITH A FEW REPORTS OF
THUNDER RECEIVED AT THE OFFICE. VERY HEAVY SNOW HAS NOW DEVELOPED
ALONG A FKS-CVX-MCD LINE WITH 1 INCH+/HOUR RATES PER SPOTTERS. AT
THE SAME TIME...HEAVY SNOWS CONTINUE OVER MUCH OF INTERIOR
NORTHERN LOWER...AND EASTERN UPPER /ESP ALONG I-75 PER SPOTTERS/.
GIVEN THIS EVOLUTION...WILL LEAVE GOING HEADLINES IN PLACE AS OF
THIS TIME. PRIMARY AREA OF CONCERN /OF LESS THAN WARNING LEVEL
SNOWS OVERNIGHT/ IS FROM TVC TO MBL...WHERE A GAP IN THE ECHOES
HAVE DEVELOPED WITH THE BETTER SOUTH-NORTH MOISTURE FEED FURTHER
EAST. STILL EXPECT...HOWEVER...THAT AS WE START TO GET THE LAKE
INVOLVED LATER TONIGHT THAT THIS WILL FILL BACK IN WITH
SIGNIFICANT ACCUMS. WITH WINDS KICKING UP HERE AFTER
MIDNIGHT...EXPECT A VERY HAZARDOUS MORNING COMMUTE...AND THUS THE
WARNING WILL REMAIN.
LOW PRESSURE LOOKS TO HAVE REACHED PEAK INTENSITY WITH OBS OVER
SOUTHWEST LOWER MICHIGAN SHOWING 985MB...HAVING COME UP 1-2 MB IN
THE LAST FEW HOURS. THUS...AS THE OCCLUSION PROCESS GETS
GOING...EXPECT OUR TRANSITION TO A COOLER AIRMASS TO GO AS
EXPECTED...WITH SNOWS COLLAPSING TO THE COAST OF NORTHEAST LOWER
AFTER MIDNIGHT.
UPDATE ISSUED AT 704 PM EST THU DEC 20 2012
TERRIFIC WV SATELLITE PRESENTATION OF OUR WINTER STORM AS H5 LOW
CROSSES THROUGH NORTHERN INDIANA WITH 984 MB LOW EMERGING OVER
SOUTHWEST LOWER MICHIGAN. CLASSIC TRACK TO KEEP NEARLY ALL OF OUR
CWA IN THE DEFORMATION PRECIPITATION THROUGH THE OVERNIGHT. RECENT
TRENDS IN THE DUAL POL PRODUCTS SUGGESTS A TRANSITION BACK TO SNOW IS
COMPLETE FROM MBL TO TVC...WITH VSBY RESTRICTIONS BECOMING GREATER
AT THESE SITES AS THE SNOWFALL INTENSITY INCREASES. A RAIN/SNOW
MIX...OR JUST PLAIN RAIN CONTINUES FROM CAD TO HTL TO APN WITH
ROGERS CITY SHIFTING TO RAIN LAST HOUR. THIS LINES UP FAIRLY WELL
WITH RECENT RAP TRENDS...WITH NEW APX RAOB SHOWING THE RAP IS
ABOUT 1C TOO WARM THROUGH THE LLEVELS. THUS...HAVE ONLY NEEDED
SOME MINOR TWEAKS TO THE WEATHER GRIDS FOR THE NEXT FEW HOURS.
PRECIPITATION RATES LOOK TO REMAIN IMPRESSIVE WITH CONVECTIVE
ELEMENTS CONTINUING TO FEED THE DEFORMATION BAND.
THEREFORE...OCCASIONAL 1-2"/HOUR SNOWFALL RATES LOOK PLAUSIBLE
THROUGH AT LEAST 06Z...AND THUS OVERNIGHT SNOWFALL AMOUNTS OF 6"+
FOR FAR NORTHERN LOWER AND EASTERN UPPER STILL LOOK GOOD. A
TERRIBLE TRAVEL NIGHT FOR SURE...WITH SOME POWER OUTAGES REPORTED
/AND LIKELY TO CONTINUE AND PERHAPS EXPAND AS WINDS GET GOING
AFTER MIDNIGHT/.
UPDATE ISSUED AT 556 PM EST THU DEC 20 2012
LOW PRESSURE CROSSING SOUTHERN LAKE MICHIGAN AT THIS HOUR...NEAR
983 MB /STILL A LITTLE BELOW NEAR TERM RUC GUIDANCE/. RAIN-SNOW
LINE HAS BEEN FLIRTING WITH THE TVC-GOV-APN CORRIDOR AND THIS IS
IN GOOD AGREEMENT WITH H8 WETBULB ZERO LINE. EXPECT THAT THIS WILL
SHIFT A LITTLE FURTHER NORTH AND EAST THIS EVENING UNTIL THE LOW
REACHES OUR LONGITUDE AROUND 9-10PM...IN LINE WITH RAP
EXPECTATIONS.
PRIMARY CHANGES INCLUDE REMOVING BLOWING SNOW MENTION THROUGH THE
EVENING UNTIL WE CAN GET THE NNW WINDS TO STRENGTHEN IN
COMBINATION WITH SLOWLY COOLING BL TEMPS. HAVE ALSO ADJUSTED
WEATHER GRIDS TO ACCOUNT FOR EXPECTED MOVEMENT OF THE RAIN/SNOW
LINE. FINALLY...HAVE ADJUSTED OVERNIGHT PRECIPITATION TOTALS PER
LATEST HRRR/RAP...BUT THIS ONLY RESULTS IN A MINOR CHANGE TO
PREVIOUS GRIDDED FORECAST. STILL EXPECT SOME SPOTS OVER INTERIOR
NORTHERN LOWER AND EASTERN UPPER TO SEE UPWARDS OF 6 ADDITIONAL
INCHES OVERNIGHT. WHILE A LITTLE LESS WILL FALL AT THE COASTS...IT
WILL BE FAR MORE THAN HAS BEEN SEEN THUS FAR...THEREFORE CAUSING
TRAVEL CONDITIONS IN THESE REGIONS TO DETERIORATE RAPIDLY.
HAVE ISSUED AN SPS TO HIGHLIGHT THE CHANGING EVENING CONDITIONS.
OTHERWISE...HEADLINES LOOK GOOD. WILL REASSESS OUR FAR SOUTHEAST
FOR POTENTIAL WINTER WEATHER ADVISORY NEEDED WELL AFTER MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
ON THE LATEST SURFACE WEATHER MAP OF INTEREST...984 MB LOW PRESSURE
WAS CENTERED NEAR CHICAGO ILLINOIS. APX AND SURROUNDING RADARS
SHOWED MODERATE TO HEAVY PRECIPITATION ACROSS MUCH OF NORTHERN
MICHIGAN. THE FORM OF WHICH IS ALL OVER THE MAP...SOME SPOTS ACROSS
THE HIGHER TERRAIN HAS HAD 6 INCHES OR MORE...WHILE THE LOWER
ELEVATIONS HAVE HAD 2 INCHES OR LESS (IN SOME CASES NEARLY NONE AT
ALL). FORECAST CHALLENGES ARE NUMEROUS WITH CHANGEOVER TO ALL SNOW
AND ADDITIONAL ACCUMULATIONS THE MAIN ONES.
TONIGHT...STORM SYSTEM WILL CONTINUE TO TRACK NORTHEAST ACROSS LOWER
MICHIGAN TONIGHT THEN INTO WESTERN NEW YORK FRIDAY. SNOWFALL RATES
ARE EXPECTED TO PICK UP ONCE AGAIN AND AS COLDER AIR GETS PULLED
INTO THE REGION FROM THE NORTH...SNOWFALL RATES ARE EXPECTED TO
INCREASE. WATER VAPOR LOOPS DEPICT A WELL-DEFINED BAROCLINIC LEAF
STRUCTURE. ACCOMPANYING STRONG DIVERGENCE WITHIN A COUPLED UPPER JET
STRUCTURE ATOP LOW/MID-LEVEL FRONTOGENESIS WILL SUPPORT AN INCREASE
IN SNOW RATES DURING THE NEXT FEW HOURS. DEEP ASCENT THROUGH
DENDRITIC GROWTH ZONES WITHIN THE 700-500-MB LAYER WILL SUPPORT
EFFICIENT SNOW GROWTH...WITH ISOTHERMAL PROFILES IN THE 850-700-MB
LAYER YIELDING EFFICIENT SNOW AGGREGATION. SNOWFALL RATES OF 1-1.5
INCHES WILL LIKELY BECOME COMMON LATER THIS EVENING...AS ONE OR MORE
NE/SW-ORIENTED SNOW BANDS DEVELOP WHILE THE SFC LOW APPROACHES. THE
ENHANCED SFC PRESSURE GRADIENT WILL SUPPORT NNE TO ENE WINDS OF
20-25 MPH WITH GUSTS REACHING 30 TO OCCASIONALLY 35 MPH. THIS WILL
SUPPORT REDUCED VISIBILITIES TO ONE-HALF MILE IN BLOWING SNOW...AND
LOCALIZED BLIZZARD CONDITIONS MAY OCCUR. ADDITIONAL ACCUMULATIONS
WILL VARY WIDELY FROM AN INCH OR LESS NEAR THE LAKE HURON LAKE
SHORES TO BETWEEN 4 AND 8 INCHES ACROSS EASTERN UPPER AND THE HIGHER
TERRAIN OF NORTHERN LOWER. LOWS RANGING FROM THE MIDDLE 20S NORTH TO
THE LOWER 30S SOUTHEAST.
FRIDAY...WRAP AROUND SNOW SHOWERS IN THE MORNING THEN DRIER
AIR/SUBSIDENCE/RIDGING BY LATE IN THE DAY WHICH SHOULD DIMINISH
ACTIVITY. THERE IS ALSO A BIT OF OVER LAKE INSTABILITY (DELTA TS OF
ABOUT 14) WITH STRONG NORTHERLY FLOW. THIS WILL LEAD TO WIDESPREAD
BLOWING AND DRIFTING SNOW...WITH ONLY ABOUT 2 INCHES OR LESS OF
ADDITIONAL ACTUAL ACCUMULATION. HIGHS IN THE UPPER 20S NORTH TO THE
MIDDLE 30S SOUTHEAST.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
FOUR WAVE NRN HEMISPHERIC PATTERN IN PLACE TODAY WITH MAJOR TROUGH
AXES OVER FAR EASTERN ASIA AND ALONG THE NOAM WEST COAST. SW
FLOW/RIDGING AND RELATIVELY MILD TEMPERATURES EXISTS DOWNSTREAM
THROUGH THE PLAINS AND THE EASTERN CONUS...WITH MUCH OF NRN MICHIGAN
JUST COLD ENOUGH TO GET IN ON THE HEAVY SNOW WITH OUR ONGOING WINTER
STORM (ACTUALLY PARTS OF THE CWA IS WITHIN THE SWEET SPOT...THE
TRANSITION ZONE FROM RAIN TO SNOW WHERE YOU GET MAXIMUM MOISTURE
INFLOW). FLOW PATTERN REMAINS SOMEWHAT PROGRESSIVE ACROSS THE CONUS
THROUGH THE UPCOMING SEVEN DAY STRETCH BUT STILL ON THE OVERALL MILD
SIDE OF THE THINGS AS THE REALLY COLD AIR REMAINS STUCK ACROSS THE
POLE INTO EASTERN ASIA...A PATTERN THAT HAS DOMINATED THIS
FALL/EARLY WINTER SEASON SO FAR. BUT FIRST...HAVE TO GET THROUGH THE
ONGOING STORM.
FRIDAY NIGHT AND SATURDAY...ONGOING STRONG SYSTEM WILL BE EXITING
EAST OF THE STATE BY FRIDAY EVENING WITH MID LEVEL RIDING/SFC HIGH
PRESSURE AND DRIER AIR NOSING INTO THE WESTERN GREAT LAKES THROUGH
THE NIGHT. NNW FLOW LAKE SNOW SHOWERS AND GUSTY WINDS WILL PERSIST
THROUGH FRIDAY EVENING BEFORE DIMINISHING SUBSTANTIALLY OVERNIGHT
INTO THE DAY SATURDAY. ACCORDINGLY...WILL START OUT WITH CATEGORICAL
NNW FLOW LAKE SNOW SHOWERS FRIDAY EVENING BEFORE DIMINISHING/ENDING
BY SATURDAY MORNING. CURR
SATURDAY NIGHT THROUGH CHRISTMAS EVE...A RELATIVE LULL IN THE
WEATHER ACTION FOR THE LATTER HALF OF THE WEEKEND THROUGH CHRISTMAS
EVE WITH BROAD HIGH PRESSURE AND WEDGE OF DRIER AIR IN THE REGION.
THAT SAID...GUIDANCE DOES DEPICT A COUPLE WAVES WITHIN THE FAST NW
FLOW ALOFT SKITING THROUGH THE NRN PART OF THE STATE...ONE SATURDAY
NIGHT AND A STRONGER ONE ON SUNDAY. SOME COLDER AIR SAGGING BACK
INTO THE REGION BEHIND THE WAVE ENOUGH TO MAINTAIN AND/OR GENERATE
SOME LAKE SNOWS OFF THE GREAT LAKES...ESPECIALLY SUNDAY AS THE
STRONGER WAVE PASSES THROUGH. BUT OVERALL NOT A BIG DEAL WITH FAIRLY
DRY AIR IN CONTROL. SUNDAY NIGHT THROUGH CHRISTMAS EVE LOOKING QUIET
AT THIS POINT WITH BROAD HIGH PRESSURE THROUGH THE REGION.
CHRISTMAS DAY THROUGH THURSDAY (EXTENDED PERIODS)...SOLUTION
DIFFERENCES AMONG THE MEDIUM RANGE GUIDANCE...AS USUAL. GEM/GFS
SOLUTIONS ARE IN ONE CAMP KEEPING THINGS ON THE QUIET SIDE FOR
CHRISTMAS DAY (ALTHOUGH THE GFS DOES HAVE A WEAK FAST MOVING WAVE
MOVING THROUGH THE REGION). ECMWF HINTING AT ANOTHER STRONGER STORM
FOR TWO RUNS NOW PUSHING UP THROUGH THE OHIO VALLEY/GREAT LAKES ON
CHRISTMAS DAY. DIFFERENCES AMONG THE GUIDANCE ARE THE RESULT OF THE
DEGREE OF PHASING BETWEEN THE NRN AND SOUTHERN STREAMS WITH OBVIOUS
BIG IMPLICATIONS. NO WAY OF KNOWING THE CORRECT SOLUTION AT THIS
JUNCTURE...BUT WILL HAVE LOWER END SNOW CHANCES ON TUESDAY FOR NOW.
ANOTHER SHOT FOR A STORM SYSTEM MAY COME WEDNESDAY NIGHT THROUGH
THURSDAY WITH THE POTENTIAL FOR YET ANOTHER STORM TO SPIN UP OFF THE
GULF AND LIFT NORTHWARD THROUGH THE EASTERN CONUS. AGAIN...BIG
DIFFERENCES ON THE TIME/TRACK OF THAT STORM (IF IT OCCURS AT ALL).
BUT WILL CARRY CHANCE POPS FOR SNOW DURING THAT TIME.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 638 PM EST THU DEC 20 2012
CHANGEOVER TO ALL SNOW HAS OCCURRED AT MBL AND TVC....WITH SNOW AT
PLN AND RAIN ONGOING AT APN. OVERNIGHT...LOW PRESSURE OVER
SOUTHERN LAKE MICHIGAN WILL LIFT NORTH AND EAST...WITH MODERATE
TO OCCASIONALLY HEAVY SNOW AT TVC/MBL/PLN FOR THE BALANCE OF THE
NIGHT WITH VLIFR-LIFR CONDITIONS. THESE CONDITIONS WILL REACH APN
AFTER ABOUT 9Z AS RAIN CHANGES OVER TO SNOW. TOWARDS DAYBREAK AND
THR0UGH THE DAY ON FRIDAY...SNOW WILL TAPER TO LAKE EFFECT SNOW
SHOWERS THAT WILL IMPACT PRIMARILY TVC AND APN...WITH
NORTHWESTERLY WINDS INCREASING TO 25G35KTS...WHICH WILL CAUSE
BLOWING SNOW AT ALL SITES. EXPECT RESTRICTIONS TO TRANSITION TO
MORE MVFR BY FRIDAY AFTERNOON DUE TO BLSN AND CIGS.
&&
.MARINE...
ISSUED AT 414 PM EST THU DEC 20 2012
MAJOR WINTER STORM LIFTING NE INTO THE GREAT LAKES THROUGH
TONIGHT...BEFORE DEPARTING FRIDAY. OVERLAKE INSTABILITY WITH
EASTERLY WINDS AT 20-35KTS TO DEVELOP AS MODERATE TO HEAVY SNOWS
(MIXED WITH OR ALL RAIN ACROSS LAKE HURON). THE SNOWS WILL BE
INCREASINGLY INTENSE THIS EVENING. WINDS WILL DECREASE SOME ACROSS A
GOOD CHUNK OF THE NEARSHORES THIS EVENING...BUT THEN RAMP BACK UP
AGAIN LATE TONIGHT AND FRIDAY WITH COLD ADVECTION FOLLOWING THE
DEPARTING SFC LOW PRESSURE. WINDS WILL GUST AS HIGH AS
50KTS...RESULTING IN STORM FORCE WINDS FOR THE NW LOWER NEARSHORES.
SOLID GALES ALL OTHER MARINE AREAS. GRADIENT GRADUALLY LOOSENS UP
OVER THE WEEKEND...BUT GALES AND OBVIOUSLY CHOPPY WAVES WILL PERSIST
THROUGH FRIDAY NIGHT.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 7 PM EST FRIDAY FOR MIZ008-015>029-
031>034.
WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ030-035-041.
LH...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LHZ345>349.
LM...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LMZ341.
STORM WARNING UNTIL 7 PM EST FRIDAY FOR LMZ323-342-344>346.
GALE WARNING FROM 7 PM FRIDAY TO 7 AM EST SATURDAY FOR LMZ323-
342-344>346.
LS...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LSZ321-322.
&&
$$
UPDATE...JA
SYNOPSIS...TL
SHORT TERM...AS
LONG TERM...BA
AVIATION...JA
MARINE...AS
AREA FORECAST DISCUSSION...UPDATED
NWS GAYLORD MI
850 PM EST THU DEC 20 2012
.SYNOPSIS...
ISSUED AT 414 PM EST THU DEC 20 2012
STRONG LOW PRESSURE OVER THE SOUTHERN GREAT LAKES...WILL CONTINUE TO
LIFT INTO SOUTHERN MICHIGAN...GENERATING CONTINUED WINTRY WEATHER
ACROSS NORTHERN MICHIGAN THROUGH FRIDAY. PERIODS OF HEAVY SNOW IS
EXPECTED FOR AREAS OF NORTHERN MICHIGAN THROUGH FRIDAY AFTERNOON.
ANY PRECIPITATION FALLING AS RAIN OR A RAIN....SNOW MIX WILL CHANGE
OVER TO SNOW THIS EVENING. WINDS WILL INCREASE TONIGHT AND CONTINUE
THROUGH FRIDAY.
&&
.UPDATE...
ISSUED AT 834 PM EST THU DEC 20 2012
LOOKING OUT THE WINDOW HERE AT APX REVEALS MODERATE TO HEAVY
SNOW...WITH RIMED DENDRITES SUGGESTING FAIRLY "WET" SNOW TO
LIQUID RATIOS /7-10:1/...IN AGREEMENT WITH EVENING OBSERVATIONS.
NOT SURPRISINGLY...CURRENT LIGHTNING DATA SHOWS SOME IN CLOUD
FLASHES OVER AND NEAR LITTLE TRAVERSE BAY...WITH A FEW REPORTS OF
THUNDER RECEIVED AT THE OFFICE. VERY HEAVY SNOW HAS NOW DEVELOPED
ALONG A FKS-CVX-MCD LINE WITH 1 INCH+/HOUR RATES PER SPOTTERS. AT
THE SAME TIME...HEAVY SNOWS CONTINUE OVER MUCH OF INTERIOR
NORTHERN LOWER...AND EASTERN UPPER /ESP ALONG I-75 PER SPOTTERS/.
GIVEN THIS EVOLUTION...WILL LEAVE GOING HEADLINES IN PLACE AS OF
THIS TIME. PRIMARY AREA OF CONCERN /OF LESS THAN WARNING LEVEL
SNOWS OVERNIGHT/ IS FROM TVC TO MBL...WHERE A GAP IN THE ECHOES
HAVE DEVELOPED WITH THE BETTER SOUTH-NORTH MOISTURE FEED FURTHER
EAST. STILL EXPECT...HOWEVER...THAT AS WE START TO GET THE LAKE
INVOLVED LATER TONIGHT THAT THIS WILL FILL BACK IN WITH
SIGNIFICANT ACCUMS. WITH WINDS KICKING UP HERE AFTER
MIDNIGHT...EXPECT A VERY HAZARDOUS MORNING COMMUTE...AND THUS THE
WARNING WILL REMAIN.
LOW PRESSURE LOOKS TO HAVE REACHED PEAK INTENSITY WITH OBS OVER
SOUTHWEST LOWER MICHIGAN SHOWING 985MB...HAVING COME UP 1-2 MB IN
THE LAST FEW HOURS. THUS...AS THE OCCLUSION PROCESS GETS
GOING...EXPECT OUR TRANSITION TO A COOLER AIRMASS TO GO AS
EXPECTED...WITH SNOWS COLLAPSING TO THE COAST OF NORTHEAST LOWER
AFTER MIDNIGHT.
UPDATE ISSUED AT 704 PM EST THU DEC 20 2012
TERRIFIC WV SATELLITE PRESENTATION OF OUR WINTER STORM AS H5 LOW
CROSSES THROUGH NORTHERN INDIANA WITH 984 MB LOW EMERGING OVER
SOUTHWEST LOWER MICHIGAN. CLASSIC TRACK TO KEEP NEARLY ALL OF OUR
CWA IN THE DEFORMATION PRECIPITATION THROUGH THE OVERNIGHT. RECENT
TRENDS IN THE DUAL POL PRODUCTS SUGGESTS A TRANSITION BACK TO SNOW IS
COMPLETE FROM MBL TO TVC...WITH VSBY RESTRICTIONS BECOMING GREATER
AT THESE SITES AS THE SNOWFALL INTENSITY INCREASES. A RAIN/SNOW
MIX...OR JUST PLAIN RAIN CONTINUES FROM CAD TO HTL TO APN WITH
ROGERS CITY SHIFTING TO RAIN LAST HOUR. THIS LINES UP FAIRLY WELL
WITH RECENT RAP TRENDS...WITH NEW APX RAOB SHOWING THE RAP IS
ABOUT 1C TOO WARM THROUGH THE LLEVELS. THUS...HAVE ONLY NEEDED
SOME MINOR TWEAKS TO THE WEATHER GRIDS FOR THE NEXT FEW HOURS.
PRECIPITATION RATES LOOK TO REMAIN IMPRESSIVE WITH CONVECTIVE
ELEMENTS CONTINUING TO FEED THE DEFORMATION BAND.
THEREFORE...OCCASIONAL 1-2"/HOUR SNOWFALL RATES LOOK PLAUSIBLE
THROUGH AT LEAST 06Z...AND THUS OVERNIGHT SNOWFALL AMOUNTS OF 6"+
FOR FAR NORTHERN LOWER AND EASTERN UPPER STILL LOOK GOOD. A
TERRIBLE TRAVEL NIGHT FOR SURE...WITH SOME POWER OUTAGES REPORTED
/AND LIKELY TO CONTINUE AND PERHAPS EXPAND AS WINDS GET GOING
AFTER MIDNIGHT/.
UPDATE ISSUED AT 556 PM EST THU DEC 20 2012
LOW PRESSURE CROSSING SOUTHERN LAKE MICHIGAN AT THIS HOUR...NEAR
983 MB /STILL A LITTLE BELOW NEAR TERM RUC GUIDANCE/. RAIN-SNOW
LINE HAS BEEN FLIRTING WITH THE TVC-GOV-APN CORRIDOR AND THIS IS
IN GOOD AGREEMENT WITH H8 WETBULB ZERO LINE. EXPECT THAT THIS WILL
SHIFT A LITTLE FURTHER NORTH AND EAST THIS EVENING UNTIL THE LOW
REACHES OUR LONGITUDE AROUND 9-10PM...IN LINE WITH RAP
EXPECTATIONS.
PRIMARY CHANGES INCLUDE REMOVING BLOWING SNOW MENTION THROUGH THE
EVENING UNTIL WE CAN GET THE NNW WINDS TO STRENGTHEN IN
COMBINATION WITH SLOWLY COOLING BL TEMPS. HAVE ALSO ADJUSTED
WEATHER GRIDS TO ACCOUNT FOR EXPECTED MOVEMENT OF THE RAIN/SNOW
LINE. FINALLY...HAVE ADJUSTED OVERNIGHT PRECIPITATION TOTALS PER
LATEST HRRR/RAP...BUT THIS ONLY RESULTS IN A MINOR CHANGE TO
PREVIOUS GRIDDED FORECAST. STILL EXPECT SOME SPOTS OVER INTERIOR
NORTHERN LOWER AND EASTERN UPPER TO SEE UPWARDS OF 6 ADDITIONAL
INCHES OVERNIGHT. WHILE A LITTLE LESS WILL FALL AT THE COASTS...IT
WILL BE FAR MORE THAN HAS BEEN SEEN THUS FAR...THEREFORE CAUSING
TRAVEL CONDITIONS IN THESE REGIONS TO DETERIORATE RAPIDLY.
HAVE ISSUED AN SPS TO HIGHLIGHT THE CHANGING EVENING CONDITIONS.
OTHERWISE...HEADLINES LOOK GOOD. WILL REASSESS OUR FAR SOUTHEAST
FOR POTENTIAL WINTER WEATHER ADVISORY NEEDED WELL AFTER MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
ON THE LATEST SURFACE WEATHER MAP OF INTEREST...984 MB LOW PRESSURE
WAS CENTERED NEAR CHICAGO ILLINOIS. APX AND SURROUNDING RADARS
SHOWED MODERATE TO HEAVY PRECIPITATION ACROSS MUCH OF NORTHERN
MICHIGAN. THE FORM OF WHICH IS ALL OVER THE MAP...SOME SPOTS ACROSS
THE HIGHER TERRAIN HAS HAD 6 INCHES OR MORE...WHILE THE LOWER
ELEVATIONS HAVE HAD 2 INCHES OR LESS (IN SOME CASES NEARLY NONE AT
ALL). FORECAST CHALLENGES ARE NUMEROUS WITH CHANGEOVER TO ALL SNOW
AND ADDITIONAL ACCUMULATIONS THE MAIN ONES.
TONIGHT...STORM SYSTEM WILL CONTINUE TO TRACK NORTHEAST ACROSS LOWER
MICHIGAN TONIGHT THEN INTO WESTERN NEW YORK FRIDAY. SNOWFALL RATES
ARE EXPECTED TO PICK UP ONCE AGAIN AND AS COLDER AIR GETS PULLED
INTO THE REGION FROM THE NORTH...SNOWFALL RATES ARE EXPECTED TO
INCREASE. WATER VAPOR LOOPS DEPICT A WELL-DEFINED BAROCLINIC LEAF
STRUCTURE. ACCOMPANYING STRONG DIVERGENCE WITHIN A COUPLED UPPER JET
STRUCTURE ATOP LOW/MID-LEVEL FRONTOGENESIS WILL SUPPORT AN INCREASE
IN SNOW RATES DURING THE NEXT FEW HOURS. DEEP ASCENT THROUGH
DENDRITIC GROWTH ZONES WITHIN THE 700-500-MB LAYER WILL SUPPORT
EFFICIENT SNOW GROWTH...WITH ISOTHERMAL PROFILES IN THE 850-700-MB
LAYER YIELDING EFFICIENT SNOW AGGREGATION. SNOWFALL RATES OF 1-1.5
INCHES WILL LIKELY BECOME COMMON LATER THIS EVENING...AS ONE OR MORE
NE/SW-ORIENTED SNOW BANDS DEVELOP WHILE THE SFC LOW APPROACHES. THE
ENHANCED SFC PRESSURE GRADIENT WILL SUPPORT NNE TO ENE WINDS OF
20-25 MPH WITH GUSTS REACHING 30 TO OCCASIONALLY 35 MPH. THIS WILL
SUPPORT REDUCED VISIBILITIES TO ONE-HALF MILE IN BLOWING SNOW...AND
LOCALIZED BLIZZARD CONDITIONS MAY OCCUR. ADDITIONAL ACCUMULATIONS
WILL VARY WIDELY FROM AN INCH OR LESS NEAR THE LAKE HURON LAKE
SHORES TO BETWEEN 4 AND 8 INCHES ACROSS EASTERN UPPER AND THE HIGHER
TERRAIN OF NORTHERN LOWER. LOWS RANGING FROM THE MIDDLE 20S NORTH TO
THE LOWER 30S SOUTHEAST.
FRIDAY...WRAP AROUND SNOW SHOWERS IN THE MORNING THEN DRIER
AIR/SUBSIDENCE/RIDGING BY LATE IN THE DAY WHICH SHOULD DIMINISH
ACTIVITY. THERE IS ALSO A BIT OF OVER LAKE INSTABILITY (DELTA TS OF
ABOUT 14) WITH STRONG NORTHERLY FLOW. THIS WILL LEAD TO WIDESPREAD
BLOWING AND DRIFTING SNOW...WITH ONLY ABOUT 2 INCHES OR LESS OF
ADDITIONAL ACTUAL ACCUMULATION. HIGHS IN THE UPPER 20S NORTH TO THE
MIDDLE 30S SOUTHEAST.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
FOUR WAVE NRN HEMISPHERIC PATTERN IN PLACE TODAY WITH MAJOR TROUGH
AXES OVER FAR EASTERN ASIA AND ALONG THE NOAM WEST COAST. SW
FLOW/RIDGING AND RELATIVELY MILD TEMPERATURES EXISTS DOWNSTREAM
THROUGH THE PLAINS AND THE EASTERN CONUS...WITH MUCH OF NRN MICHIGAN
JUST COLD ENOUGH TO GET IN ON THE HEAVY SNOW WITH OUR ONGOING WINTER
STORM (ACTUALLY PARTS OF THE CWA IS WITHIN THE SWEET SPOT...THE
TRANSITION ZONE FROM RAIN TO SNOW WHERE YOU GET MAXIMUM MOISTURE
INFLOW). FLOW PATTERN REMAINS SOMEWHAT PROGRESSIVE ACROSS THE CONUS
THROUGH THE UPCOMING SEVEN DAY STRETCH BUT STILL ON THE OVERALL MILD
SIDE OF THE THINGS AS THE REALLY COLD AIR REMAINS STUCK ACROSS THE
POLE INTO EASTERN ASIA...A PATTERN THAT HAS DOMINATED THIS
FALL/EARLY WINTER SEASON SO FAR. BUT FIRST...HAVE TO GET THROUGH THE
ONGOING STORM.
FRIDAY NIGHT AND SATURDAY...ONGOING STRONG SYSTEM WILL BE EXITING
EAST OF THE STATE BY FRIDAY EVENING WITH MID LEVEL RIDING/SFC HIGH
PRESSURE AND DRIER AIR NOSING INTO THE WESTERN GREAT LAKES THROUGH
THE NIGHT. NNW FLOW LAKE SNOW SHOWERS AND GUSTY WINDS WILL PERSIST
THROUGH FRIDAY EVENING BEFORE DIMINISHING SUBSTANTIALLY OVERNIGHT
INTO THE DAY SATURDAY. ACCORDINGLY...WILL START OUT WITH CATEGORICAL
NNW FLOW LAKE SNOW SHOWERS FRIDAY EVENING BEFORE DIMINISHING/ENDING
BY SATURDAY MORNING. CURR
SATURDAY NIGHT THROUGH CHRISTMAS EVE...A RELATIVE LULL IN THE
WEATHER ACTION FOR THE LATTER HALF OF THE WEEKEND THROUGH CHRISTMAS
EVE WITH BROAD HIGH PRESSURE AND WEDGE OF DRIER AIR IN THE REGION.
THAT SAID...GUIDANCE DOES DEPICT A COUPLE WAVES WITHIN THE FAST NW
FLOW ALOFT SKITING THROUGH THE NRN PART OF THE STATE...ONE SATURDAY
NIGHT AND A STRONGER ONE ON SUNDAY. SOME COLDER AIR SAGGING BACK
INTO THE REGION BEHIND THE WAVE ENOUGH TO MAINTAIN AND/OR GENERATE
SOME LAKE SNOWS OFF THE GREAT LAKES...ESPECIALLY SUNDAY AS THE
STRONGER WAVE PASSES THROUGH. BUT OVERALL NOT A BIG DEAL WITH FAIRLY
DRY AIR IN CONTROL. SUNDAY NIGHT THROUGH CHRISTMAS EVE LOOKING QUIET
AT THIS POINT WITH BROAD HIGH PRESSURE THROUGH THE REGION.
CHRISTMAS DAY THROUGH THURSDAY (EXTENDED PERIODS)...SOLUTION
DIFFERENCES AMONG THE MEDIUM RANGE GUIDANCE...AS USUAL. GEM/GFS
SOLUTIONS ARE IN ONE CAMP KEEPING THINGS ON THE QUIET SIDE FOR
CHRISTMAS DAY (ALTHOUGH THE GFS DOES HAVE A WEAK FAST MOVING WAVE
MOVING THROUGH THE REGION). ECMWF HINTING AT ANOTHER STRONGER STORM
FOR TWO RUNS NOW PUSHING UP THROUGH THE OHIO VALLEY/GREAT LAKES ON
CHRISTMAS DAY. DIFFERENCES AMONG THE GUIDANCE ARE THE RESULT OF THE
DEGREE OF PHASING BETWEEN THE NRN AND SOUTHERN STREAMS WITH OBVIOUS
BIG IMPLICATIONS. NO WAY OF KNOWING THE CORRECT SOLUTION AT THIS
JUNCTURE...BUT WILL HAVE LOWER END SNOW CHANCES ON TUESDAY FOR NOW.
ANOTHER SHOT FOR A STORM SYSTEM MAY COME WEDNESDAY NIGHT THROUGH
THURSDAY WITH THE POTENTIAL FOR YET ANOTHER STORM TO SPIN UP OFF THE
GULF AND LIFT NORTHWARD THROUGH THE EASTERN CONUS. AGAIN...BIG
DIFFERENCES ON THE TIME/TRACK OF THAT STORM (IF IT OCCURS AT ALL).
BUT WILL CARRY CHANCE POPS FOR SNOW DURING THAT TIME.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 638 PM EST THU DEC 20 2012
CHANGEOVER TO ALL SNOW HAS OCCURRED AT MBL AND TVC....WITH SNOW AT
PLN AND RAIN ONGOING AT APN. OVERNIGHT...LOW PRESSURE OVER
SOUTHERN LAKE MICHIGAN WILL LIFT NORTH AND EAST...WITH MODERATE
TO OCCASIONALLY HEAVY SNOW AT TVC/MBL/PLN FOR THE BALANCE OF THE
NIGHT WITH VLIFR-LIFR CONDITIONS. THESE CONDITIONS WILL REACH APN
AFTER ABOUT 9Z AS RAIN CHANGES OVER TO SNOW. TOWARDS DAYBREAK AND
THR0UGH THE DAY ON FRIDAY...SNOW WILL TAPER TO LAKE EFFECT SNOW
SHOWERS THAT WILL IMPACT PRIMARILY TVC AND APN...WITH
NORTHWESTERLY WINDS INCREASING TO 25G35KTS...WHICH WILL CAUSE
BLOWING SNOW AT ALL SITES. EXPECT RESTRICTIONS TO TRANSITION TO
MORE MVFR BY FRIDAY AFTERNOON DUE TO BLSN AND CIGS.
&&
.MARINE...
ISSUED AT 414 PM EST THU DEC 20 2012
MAJOR WINTER STORM LIFTING NE INTO THE GREAT LAKES THROUGH
TONIGHT...BEFORE DEPARTING FRIDAY. OVERLAKE INSTABILITY WITH
EASTERLY WINDS AT 20-35KTS TO DEVELOP AS MODERATE TO HEAVY SNOWS
(MIXED WITH OR ALL RAIN ACROSS LAKE HURON). THE SNOWS WILL BE
INCREASINGLY INTENSE THIS EVENING. WINDS WILL DECREASE SOME ACROSS A
GOOD CHUNK OF THE NEARSHORES THIS EVENING...BUT THEN RAMP BACK UP
AGAIN LATE TONIGHT AND FRIDAY WITH COLD ADVECTION FOLLOWING THE
DEPARTING SFC LOW PRESSURE. WINDS WILL GUST AS HIGH AS
50KTS...RESULTING IN STORM FORCE WINDS FOR THE NW LOWER NEARSHORES.
SOLID GALES ALL OTHER MARINE AREAS. GRADIENT GRADUALLY LOOSENS UP
OVER THE WEEKEND...BUT GALES AND OBVIOUSLY CHOPPY WAVES WILL PERSIST
THROUGH FRIDAY NIGHT.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 7 PM EST FRIDAY FOR MIZ008-015>029-
031>034.
WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ030-035-041.
LH...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LHZ345>349.
LM...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LMZ341.
STORM WARNING UNTIL 7 PM EST FRIDAY FOR LMZ323-342-344>346.
GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LMZ323-342-344>346.
GALE WARNING FROM 7 PM FRIDAY TO 7 AM EST SATURDAY FOR LMZ323-
342-344>346.
LS...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LSZ321-322.
&&
$$
UPDATE...JA
SYNOPSIS...TL
SHORT TERM...AS
LONG TERM...BA
AVIATION...JA
MARINE...AS
AREA FORECAST DISCUSSION...UPDATED
NWS GAYLORD MI
713 PM EST THU DEC 20 2012
.SYNOPSIS...
ISSUED AT 414 PM EST THU DEC 20 2012
STRONG LOW PRESSURE OVER THE SOUTHERN GREAT LAKES...WILL CONTINUE TO
LIFT INTO SOUTHERN MICHIGAN...GENERATING CONTINUED WINTRY WEATHER
ACROSS NORTHERN MICHIGAN THROUGH FRIDAY. PERIODS OF HEAVY SNOW IS
EXPECTED FOR AREAS OF NORTHERN MICHIGAN THROUGH FRIDAY AFTERNOON.
ANY PRECIPITATION FALLING AS RAIN OR A RAIN....SNOW MIX WILL CHANGE
OVER TO SNOW THIS EVENING. WINDS WILL INCREASE TONIGHT AND CONTINUE
THROUGH FRIDAY.
&&
.UPDATE...
ISSUED AT 704 PM EST THU DEC 20 2012
TERRIFIC WV SATELLITE PRESENTATION OF OUR WINTER STORM AS H5 LOW
CROSSES THROUGH NORTHERN INDIANA WITH 984 MB LOW EMERGING OVER
SOUTHWEST LOWER MICHIGAN. CLASSIC TRACK TO KEEP NEARLY ALL OF OUR
CWA IN THE DEFORMATION PRECIPITATION THROUGH THE OVERNIGHT. RECENT
TRENDS IN THE DUAL POL PRODUCTS SUGGESTS A TRANSITION BACK TO SNOW IS
COMPLETE FROM MBL TO TVC...WITH VSBY RESTRICTIONS BECOMING GREATER
AT THESE SITES AS THE SNOWFALL INTENSITY INCREASES. A RAIN/SNOW
MIX...OR JUST PLAIN RAIN CONTINUES FROM CAD TO HTL TO APN WITH
ROGERS CITY SHIFTING TO RAIN LAST HOUR. THIS LINES UP FAIRLY WELL
WITH RECENT RAP TRENDS...WITH NEW APX RAOB SHOWING THE RAP IS
ABOUT 1C TOO WARM THROUGH THE LLEVELS. THUS...HAVE ONLY NEEDED
SOME MINOR TWEAKS TO THE WEATHER GRIDS FOR THE NEXT FEW HOURS.
PRECIPITATION RATES LOOK TO REMAIN IMPRESSIVE WITH CONVECTIVE
ELEMENTS CONTINUING TO FEED THE DEFORMATION BAND.
THEREFORE...OCCASIONAL 1-2"/HOUR SNOWFALL RATES LOOK PLAUSIBLE
THROUGH AT LEAST 06Z...AND THUS OVERNIGHT SNOWFALL AMOUNTS OF 6"+
FOR FAR NORTHERN LOWER AND EASTERN UPPER STILL LOOK GOOD. A
TERRIBLE TRAVEL NIGHT FOR SURE...WITH SOME POWER OUTAGES REPORTED
/AND LIKELY TO CONTINUE AND PERHAPS EXPAND AS WINDS GET GOING
AFTER MIDNIGHT/.
UPDATE ISSUED AT 556 PM EST THU DEC 20 2012
LOW PRESSURE CROSSING SOUTHERN LAKE MICHIGAN AT THIS HOUR...NEAR
983 MB /STILL A LITTLE BELOW NEAR TERM RUC GUIDANCE/. RAIN-SNOW
LINE HAS BEEN FLIRTING WITH THE TVC-GOV-APN CORRIDOR AND THIS IS
IN GOOD AGREEMENT WITH H8 WETBULB ZERO LINE. EXPECT THAT THIS WILL
SHIFT A LITTLE FURTHER NORTH AND EAST THIS EVENING UNTIL THE LOW
REACHES OUR LONGITUDE AROUND 9-10PM...IN LINE WITH RAP
EXPECTATIONS.
PRIMARY CHANGES INCLUDE REMOVING BLOWING SNOW MENTION THROUGH THE
EVENING UNTIL WE CAN GET THE NNW WINDS TO STRENGTHEN IN
COMBINATION WITH SLOWLY COOLING BL TEMPS. HAVE ALSO ADJUSTED
WEATHER GRIDS TO ACCOUNT FOR EXPECTED MOVEMENT OF THE RAIN/SNOW
LINE. FINALLY...HAVE ADJUSTED OVERNIGHT PRECIPITATION TOTALS PER
LATEST HRRR/RAP...BUT THIS ONLY RESULTS IN A MINOR CHANGE TO
PREVIOUS GRIDDED FORECAST. STILL EXPECT SOME SPOTS OVER INTERIOR
NORTHERN LOWER AND EASTERN UPPER TO SEE UPWARDS OF 6 ADDITIONAL
INCHES OVERNIGHT. WHILE A LITTLE LESS WILL FALL AT THE COASTS...IT
WILL BE FAR MORE THAN HAS BEEN SEEN THUS FAR...THEREFORE CAUSING
TRAVEL CONDITIONS IN THESE REGIONS TO DETERIORATE RAPIDLY.
HAVE ISSUED AN SPS TO HIGHLIGHT THE CHANGING EVENING CONDITIONS.
OTHERWISE...HEADLINES LOOK GOOD. WILL REASSESS OUR FAR SOUTHEAST
FOR POTENTIAL WINTER WEATHER ADVISORY NEEDED WELL AFTER MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
ON THE LATEST SURFACE WEATHER MAP OF INTEREST...984 MB LOW PRESSURE
WAS CENTERED NEAR CHICAGO ILLINOIS. APX AND SURROUNDING RADARS
SHOWED MODERATE TO HEAVY PRECIPITATION ACROSS MUCH OF NORTHERN
MICHIGAN. THE FORM OF WHICH IS ALL OVER THE MAP...SOME SPOTS ACROSS
THE HIGHER TERRAIN HAS HAD 6 INCHES OR MORE...WHILE THE LOWER
ELEVATIONS HAVE HAD 2 INCHES OR LESS (IN SOME CASES NEARLY NONE AT
ALL). FORECAST CHALLENGES ARE NUMEROUS WITH CHANGEOVER TO ALL SNOW
AND ADDITIONAL ACCUMULATIONS THE MAIN ONES.
TONIGHT...STORM SYSTEM WILL CONTINUE TO TRACK NORTHEAST ACROSS LOWER
MICHIGAN TONIGHT THEN INTO WESTERN NEW YORK FRIDAY. SNOWFALL RATES
ARE EXPECTED TO PICK UP ONCE AGAIN AND AS COLDER AIR GETS PULLED
INTO THE REGION FROM THE NORTH...SNOWFALL RATES ARE EXPECTED TO
INCREASE. WATER VAPOR LOOPS DEPICT A WELL-DEFINED BAROCLINIC LEAF
STRUCTURE. ACCOMPANYING STRONG DIVERGENCE WITHIN A COUPLED UPPER JET
STRUCTURE ATOP LOW/MID-LEVEL FRONTOGENESIS WILL SUPPORT AN INCREASE
IN SNOW RATES DURING THE NEXT FEW HOURS. DEEP ASCENT THROUGH
DENDRITIC GROWTH ZONES WITHIN THE 700-500-MB LAYER WILL SUPPORT
EFFICIENT SNOW GROWTH...WITH ISOTHERMAL PROFILES IN THE 850-700-MB
LAYER YIELDING EFFICIENT SNOW AGGREGATION. SNOWFALL RATES OF 1-1.5
INCHES WILL LIKELY BECOME COMMON LATER THIS EVENING...AS ONE OR MORE
NE/SW-ORIENTED SNOW BANDS DEVELOP WHILE THE SFC LOW APPROACHES. THE
ENHANCED SFC PRESSURE GRADIENT WILL SUPPORT NNE TO ENE WINDS OF
20-25 MPH WITH GUSTS REACHING 30 TO OCCASIONALLY 35 MPH. THIS WILL
SUPPORT REDUCED VISIBILITIES TO ONE-HALF MILE IN BLOWING SNOW...AND
LOCALIZED BLIZZARD CONDITIONS MAY OCCUR. ADDITIONAL ACCUMULATIONS
WILL VARY WIDELY FROM AN INCH OR LESS NEAR THE LAKE HURON LAKE
SHORES TO BETWEEN 4 AND 8 INCHES ACROSS EASTERN UPPER AND THE HIGHER
TERRAIN OF NORTHERN LOWER. LOWS RANGING FROM THE MIDDLE 20S NORTH TO
THE LOWER 30S SOUTHEAST.
FRIDAY...WRAP AROUND SNOW SHOWERS IN THE MORNING THEN DRIER
AIR/SUBSIDENCE/RIDGING BY LATE IN THE DAY WHICH SHOULD DIMINISH
ACTIVITY. THERE IS ALSO A BIT OF OVER LAKE INSTABILITY (DELTA TS OF
ABOUT 14) WITH STRONG NORTHERLY FLOW. THIS WILL LEAD TO WIDESPREAD
BLOWING AND DRIFTING SNOW...WITH ONLY ABOUT 2 INCHES OR LESS OF
ADDITIONAL ACTUAL ACCUMULATION. HIGHS IN THE UPPER 20S NORTH TO THE
MIDDLE 30S SOUTHEAST.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
FOUR WAVE NRN HEMISPHERIC PATTERN IN PLACE TODAY WITH MAJOR TROUGH
AXES OVER FAR EASTERN ASIA AND ALONG THE NOAM WEST COAST. SW
FLOW/RIDGING AND RELATIVELY MILD TEMPERATURES EXISTS DOWNSTREAM
THROUGH THE PLAINS AND THE EASTERN CONUS...WITH MUCH OF NRN MICHIGAN
JUST COLD ENOUGH TO GET IN ON THE HEAVY SNOW WITH OUR ONGOING WINTER
STORM (ACTUALLY PARTS OF THE CWA IS WITHIN THE SWEET SPOT...THE
TRANSITION ZONE FROM RAIN TO SNOW WHERE YOU GET MAXIMUM MOISTURE
INFLOW). FLOW PATTERN REMAINS SOMEWHAT PROGRESSIVE ACROSS THE CONUS
THROUGH THE UPCOMING SEVEN DAY STRETCH BUT STILL ON THE OVERALL MILD
SIDE OF THE THINGS AS THE REALLY COLD AIR REMAINS STUCK ACROSS THE
POLE INTO EASTERN ASIA...A PATTERN THAT HAS DOMINATED THIS
FALL/EARLY WINTER SEASON SO FAR. BUT FIRST...HAVE TO GET THROUGH THE
ONGOING STORM.
FRIDAY NIGHT AND SATURDAY...ONGOING STRONG SYSTEM WILL BE EXITING
EAST OF THE STATE BY FRIDAY EVENING WITH MID LEVEL RIDING/SFC HIGH
PRESSURE AND DRIER AIR NOSING INTO THE WESTERN GREAT LAKES THROUGH
THE NIGHT. NNW FLOW LAKE SNOW SHOWERS AND GUSTY WINDS WILL PERSIST
THROUGH FRIDAY EVENING BEFORE DIMINISHING SUBSTANTIALLY OVERNIGHT
INTO THE DAY SATURDAY. ACCORDINGLY...WILL START OUT WITH CATEGORICAL
NNW FLOW LAKE SNOW SHOWERS FRIDAY EVENING BEFORE DIMINISHING/ENDING
BY SATURDAY MORNING. CURR
SATURDAY NIGHT THROUGH CHRISTMAS EVE...A RELATIVE LULL IN THE
WEATHER ACTION FOR THE LATTER HALF OF THE WEEKEND THROUGH CHRISTMAS
EVE WITH BROAD HIGH PRESSURE AND WEDGE OF DRIER AIR IN THE REGION.
THAT SAID...GUIDANCE DOES DEPICT A COUPLE WAVES WITHIN THE FAST NW
FLOW ALOFT SKITING THROUGH THE NRN PART OF THE STATE...ONE SATURDAY
NIGHT AND A STRONGER ONE ON SUNDAY. SOME COLDER AIR SAGGING BACK
INTO THE REGION BEHIND THE WAVE ENOUGH TO MAINTAIN AND/OR GENERATE
SOME LAKE SNOWS OFF THE GREAT LAKES...ESPECIALLY SUNDAY AS THE
STRONGER WAVE PASSES THROUGH. BUT OVERALL NOT A BIG DEAL WITH FAIRLY
DRY AIR IN CONTROL. SUNDAY NIGHT THROUGH CHRISTMAS EVE LOOKING QUIET
AT THIS POINT WITH BROAD HIGH PRESSURE THROUGH THE REGION.
CHRISTMAS DAY THROUGH THURSDAY (EXTENDED PERIODS)...SOLUTION
DIFFERENCES AMONG THE MEDIUM RANGE GUIDANCE...AS USUAL. GEM/GFS
SOLUTIONS ARE IN ONE CAMP KEEPING THINGS ON THE QUIET SIDE FOR
CHRISTMAS DAY (ALTHOUGH THE GFS DOES HAVE A WEAK FAST MOVING WAVE
MOVING THROUGH THE REGION). ECMWF HINTING AT ANOTHER STRONGER STORM
FOR TWO RUNS NOW PUSHING UP THROUGH THE OHIO VALLEY/GREAT LAKES ON
CHRISTMAS DAY. DIFFERENCES AMONG THE GUIDANCE ARE THE RESULT OF THE
DEGREE OF PHASING BETWEEN THE NRN AND SOUTHERN STREAMS WITH OBVIOUS
BIG IMPLICATIONS. NO WAY OF KNOWING THE CORRECT SOLUTION AT THIS
JUNCTURE...BUT WILL HAVE LOWER END SNOW CHANCES ON TUESDAY FOR NOW.
ANOTHER SHOT FOR A STORM SYSTEM MAY COME WEDNESDAY NIGHT THROUGH
THURSDAY WITH THE POTENTIAL FOR YET ANOTHER STORM TO SPIN UP OFF THE
GULF AND LIFT NORTHWARD THROUGH THE EASTERN CONUS. AGAIN...BIG
DIFFERENCES ON THE TIME/TRACK OF THAT STORM (IF IT OCCURS AT ALL).
BUT WILL CARRY CHANCE POPS FOR SNOW DURING THAT TIME.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 638 PM EST THU DEC 20 2012
CHANGEOVER TO ALL SNOW HAS OCCURRED AT MBL AND TVC....WITH SNOW AT
PLN AND RAIN ONGOING AT APN. OVERNIGHT...LOW PRESSURE OVER
SOUTHERN LAKE MICHIGAN WILL LIFT NORTH AND EAST...WITH MODERATE
TO OCCASIONALLY HEAVY SNOW AT TVC/MBL/PLN FOR THE BALANCE OF THE
NIGHT WITH VLIFR-LIFR CONDITIONS. THESE CONDITIONS WILL REACH APN
AFTER ABOUT 9Z AS RAIN CHANGES OVER TO SNOW. TOWARDS DAYBREAK AND
THR0UGH THE DAY ON FRIDAY...SNOW WILL TAPER TO LAKE EFFECT SNOW
SHOWERS THAT WILL IMPACT PRIMARILY TVC AND APN...WITH
NORTHWESTERLY WINDS INCREASING TO 25G35KTS...WHICH WILL CAUSE
BLOWING SNOW AT ALL SITES. EXPECT RESTRICTIONS TO TRANSITION TO
MORE MVFR BY FRIDAY AFTERNOON DUE TO BLSN AND CIGS.
&&
.MARINE...
ISSUED AT 414 PM EST THU DEC 20 2012
MAJOR WINTER STORM LIFTING NE INTO THE GREAT LAKES THROUGH
TONIGHT...BEFORE DEPARTING FRIDAY. OVERLAKE INSTABILITY WITH
EASTERLY WINDS AT 20-35KTS TO DEVELOP AS MODERATE TO HEAVY SNOWS
(MIXED WITH OR ALL RAIN ACROSS LAKE HURON). THE SNOWS WILL BE
INCREASINGLY INTENSE THIS EVENING. WINDS WILL DECREASE SOME ACROSS A
GOOD CHUNK OF THE NEARSHORES THIS EVENING...BUT THEN RAMP BACK UP
AGAIN LATE TONIGHT AND FRIDAY WITH COLD ADVECTION FOLLOWING THE
DEPARTING SFC LOW PRESSURE. WINDS WILL GUST AS HIGH AS
50KTS...RESULTING IN STORM FORCE WINDS FOR THE NW LOWER NEARSHORES.
SOLID GALES ALL OTHER MARINE AREAS. GRADIENT GRADUALLY LOOSENS UP
OVER THE WEEKEND...BUT GALES AND OBVIOUSLY CHOPPY WAVES WILL PERSIST
THROUGH FRIDAY NIGHT.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 7 PM EST FRIDAY FOR MIZ008-015>029-
031>034.
WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ030-035-041.
LH...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LHZ345>349.
LM...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LMZ341.
STORM WARNING UNTIL 7 PM EST FRIDAY FOR LMZ323-342-344>346.
GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LMZ323-342-344>346.
GALE WARNING FROM 7 PM FRIDAY TO 7 AM EST SATURDAY FOR LMZ323-
342-344>346.
LS...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LSZ321-322.
&&
$$
UPDATE...JA
SYNOPSIS...TL
SHORT TERM...AS
LONG TERM...BA
AVIATION...JA
MARINE...AS
AREA FORECAST DISCUSSION
NWS GAYLORD MI
638 PM EST THU DEC 20 2012
.SYNOPSIS...
ISSUED AT 414 PM EST THU DEC 20 2012
STRONG LOW PRESSURE OVER THE SOUTHERN GREAT LAKES...WILL CONTINUE TO
LIFT INTO SOUTHERN MICHIGAN...GENERATING CONTINUED WINTRY WEATHER
ACROSS NORTHERN MICHIGAN THROUGH FRIDAY. PERIODS OF HEAVY SNOW IS
EXPECTED FOR AREAS OF NORTHERN MICHIGAN THROUGH FRIDAY AFTERNOON.
ANY PRECIPITATION FALLING AS RAIN OR A RAIN....SNOW MIX WILL CHANGE
OVER TO SNOW THIS EVENING. WINDS WILL INCREASE TONIGHT AND CONTINUE
THROUGH FRIDAY.
&&
.UPDATE...
ISSUED AT 556 PM EST THU DEC 20 2012
LOW PRESSURE CROSSING SOUTHERN LAKE MICHIGAN AT THIS HOUR...NEAR
983 MB /STILL A LITTLE BELOW NEAR TERM RUC GUIDANCE/. RAIN-SNOW
LINE HAS BEEN FLIRTING WITH THE TVC-GOV-APN CORRIDOR AND THIS IS
IN GOOD AGREEMENT WITH H8 WETBULB ZERO LINE. EXPECT THAT THIS WILL
SHIFT A LITTLE FURTHER NORTH AND EAST THIS EVENING UNTIL THE LOW
REACHES OUR LONGITUDE AROUND 9-10PM...IN LINE WITH RAP
EXPECTATIONS.
PRIMARY CHANGES INCLUDE REMOVING BLOWING SNOW MENTION THROUGH THE
EVENING UNTIL WE CAN GET THE NNW WINDS TO STRENGTHEN IN
COMBINATION WITH SLOWLY COOLING BL TEMPS. HAVE ALSO ADJUSTED
WEATHER GRIDS TO ACCOUNT FOR EXPECTED MOVEMENT OF THE RAIN/SNOW
LINE. FINALLY...HAVE ADJUSTED OVERNIGHT PRECIPITATION TOTALS PER
LATEST HRRR/RAP...BUT THIS ONLY RESULTS IN A MINOR CHANGE TO
PREVIOUS GRIDDED FORECAST. STILL EXPECT SOME SPOTS OVER INTERIOR
NORTHERN LOWER AND EASTERN UPPER TO SEE UPWARDS OF 6 ADDITIONAL
INCHES OVERNIGHT. WHILE A LITTLE LESS WILL FALL AT THE COASTS...IT
WILL BE FAR MORE THAN HAS BEEN SEEN THUS FAR...THEREFORE CAUSING
TRAVEL CONDITIONS IN THESE REGIONS TO DETERIORATE RAPIDLY.
HAVE ISSUED AN SPS TO HIGHLIGHT THE CHANGING EVENING CONDITIONS.
OTHERWISE...HEADLINES LOOK GOOD. WILL REASSESS OUR FAR SOUTHEAST
FOR POTENTIAL WINTER WEATHER ADVISORY NEEDED WELL AFTER MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
ON THE LATEST SURFACE WEATHER MAP OF INTEREST...984 MB LOW PRESSURE
WAS CENTERED NEAR CHICAGO ILLINOIS. APX AND SURROUNDING RADARS
SHOWED MODERATE TO HEAVY PRECIPITATION ACROSS MUCH OF NORTHERN
MICHIGAN. THE FORM OF WHICH IS ALL OVER THE MAP...SOME SPOTS ACROSS
THE HIGHER TERRAIN HAS HAD 6 INCHES OR MORE...WHILE THE LOWER
ELEVATIONS HAVE HAD 2 INCHES OR LESS (IN SOME CASES NEARLY NONE AT
ALL). FORECAST CHALLENGES ARE NUMEROUS WITH CHANGEOVER TO ALL SNOW
AND ADDITIONAL ACCUMULATIONS THE MAIN ONES.
TONIGHT...STORM SYSTEM WILL CONTINUE TO TRACK NORTHEAST ACROSS LOWER
MICHIGAN TONIGHT THEN INTO WESTERN NEW YORK FRIDAY. SNOWFALL RATES
ARE EXPECTED TO PICK UP ONCE AGAIN AND AS COLDER AIR GETS PULLED
INTO THE REGION FROM THE NORTH...SNOWFALL RATES ARE EXPECTED TO
INCREASE. WATER VAPOR LOOPS DEPICT A WELL-DEFINED BAROCLINIC LEAF
STRUCTURE. ACCOMPANYING STRONG DIVERGENCE WITHIN A COUPLED UPPER JET
STRUCTURE ATOP LOW/MID-LEVEL FRONTOGENESIS WILL SUPPORT AN INCREASE
IN SNOW RATES DURING THE NEXT FEW HOURS. DEEP ASCENT THROUGH
DENDRITIC GROWTH ZONES WITHIN THE 700-500-MB LAYER WILL SUPPORT
EFFICIENT SNOW GROWTH...WITH ISOTHERMAL PROFILES IN THE 850-700-MB
LAYER YIELDING EFFICIENT SNOW AGGREGATION. SNOWFALL RATES OF 1-1.5
INCHES WILL LIKELY BECOME COMMON LATER THIS EVENING...AS ONE OR MORE
NE/SW-ORIENTED SNOW BANDS DEVELOP WHILE THE SFC LOW APPROACHES. THE
ENHANCED SFC PRESSURE GRADIENT WILL SUPPORT NNE TO ENE WINDS OF
20-25 MPH WITH GUSTS REACHING 30 TO OCCASIONALLY 35 MPH. THIS WILL
SUPPORT REDUCED VISIBILITIES TO ONE-HALF MILE IN BLOWING SNOW...AND
LOCALIZED BLIZZARD CONDITIONS MAY OCCUR. ADDITIONAL ACCUMULATIONS
WILL VARY WIDELY FROM AN INCH OR LESS NEAR THE LAKE HURON LAKE
SHORES TO BETWEEN 4 AND 8 INCHES ACROSS EASTERN UPPER AND THE HIGHER
TERRAIN OF NORTHERN LOWER. LOWS RANGING FROM THE MIDDLE 20S NORTH TO
THE LOWER 30S SOUTHEAST.
FRIDAY...WRAP AROUND SNOW SHOWERS IN THE MORNING THEN DRIER
AIR/SUBSIDENCE/RIDGING BY LATE IN THE DAY WHICH SHOULD DIMINISH
ACTIVITY. THERE IS ALSO A BIT OF OVER LAKE INSTABILITY (DELTA TS OF
ABOUT 14) WITH STRONG NORTHERLY FLOW. THIS WILL LEAD TO WIDESPREAD
BLOWING AND DRIFTING SNOW...WITH ONLY ABOUT 2 INCHES OR LESS OF
ADDITIONAL ACTUAL ACCUMULATION. HIGHS IN THE UPPER 20S NORTH TO THE
MIDDLE 30S SOUTHEAST.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
FOUR WAVE NRN HEMISPHERIC PATTERN IN PLACE TODAY WITH MAJOR TROUGH
AXES OVER FAR EASTERN ASIA AND ALONG THE NOAM WEST COAST. SW
FLOW/RIDGING AND RELATIVELY MILD TEMPERATURES EXISTS DOWNSTREAM
THROUGH THE PLAINS AND THE EASTERN CONUS...WITH MUCH OF NRN MICHIGAN
JUST COLD ENOUGH TO GET IN ON THE HEAVY SNOW WITH OUR ONGOING WINTER
STORM (ACTUALLY PARTS OF THE CWA IS WITHIN THE SWEET SPOT...THE
TRANSITION ZONE FROM RAIN TO SNOW WHERE YOU GET MAXIMUM MOISTURE
INFLOW). FLOW PATTERN REMAINS SOMEWHAT PROGRESSIVE ACROSS THE CONUS
THROUGH THE UPCOMING SEVEN DAY STRETCH BUT STILL ON THE OVERALL MILD
SIDE OF THE THINGS AS THE REALLY COLD AIR REMAINS STUCK ACROSS THE
POLE INTO EASTERN ASIA...A PATTERN THAT HAS DOMINATED THIS
FALL/EARLY WINTER SEASON SO FAR. BUT FIRST...HAVE TO GET THROUGH THE
ONGOING STORM.
FRIDAY NIGHT AND SATURDAY...ONGOING STRONG SYSTEM WILL BE EXITING
EAST OF THE STATE BY FRIDAY EVENING WITH MID LEVEL RIDING/SFC HIGH
PRESSURE AND DRIER AIR NOSING INTO THE WESTERN GREAT LAKES THROUGH
THE NIGHT. NNW FLOW LAKE SNOW SHOWERS AND GUSTY WINDS WILL PERSIST
THROUGH FRIDAY EVENING BEFORE DIMINISHING SUBSTANTIALLY OVERNIGHT
INTO THE DAY SATURDAY. ACCORDINGLY...WILL START OUT WITH CATEGORICAL
NNW FLOW LAKE SNOW SHOWERS FRIDAY EVENING BEFORE DIMINISHING/ENDING
BY SATURDAY MORNING. CURR
SATURDAY NIGHT THROUGH CHRISTMAS EVE...A RELATIVE LULL IN THE
WEATHER ACTION FOR THE LATTER HALF OF THE WEEKEND THROUGH CHRISTMAS
EVE WITH BROAD HIGH PRESSURE AND WEDGE OF DRIER AIR IN THE REGION.
THAT SAID...GUIDANCE DOES DEPICT A COUPLE WAVES WITHIN THE FAST NW
FLOW ALOFT SKITING THROUGH THE NRN PART OF THE STATE...ONE SATURDAY
NIGHT AND A STRONGER ONE ON SUNDAY. SOME COLDER AIR SAGGING BACK
INTO THE REGION BEHIND THE WAVE ENOUGH TO MAINTAIN AND/OR GENERATE
SOME LAKE SNOWS OFF THE GREAT LAKES...ESPECIALLY SUNDAY AS THE
STRONGER WAVE PASSES THROUGH. BUT OVERALL NOT A BIG DEAL WITH FAIRLY
DRY AIR IN CONTROL. SUNDAY NIGHT THROUGH CHRISTMAS EVE LOOKING QUIET
AT THIS POINT WITH BROAD HIGH PRESSURE THROUGH THE REGION.
CHRISTMAS DAY THROUGH THURSDAY (EXTENDED PERIODS)...SOLUTION
DIFFERENCES AMONG THE MEDIUM RANGE GUIDANCE...AS USUAL. GEM/GFS
SOLUTIONS ARE IN ONE CAMP KEEPING THINGS ON THE QUIET SIDE FOR
CHRISTMAS DAY (ALTHOUGH THE GFS DOES HAVE A WEAK FAST MOVING WAVE
MOVING THROUGH THE REGION). ECMWF HINTING AT ANOTHER STRONGER STORM
FOR TWO RUNS NOW PUSHING UP THROUGH THE OHIO VALLEY/GREAT LAKES ON
CHRISTMAS DAY. DIFFERENCES AMONG THE GUIDANCE ARE THE RESULT OF THE
DEGREE OF PHASING BETWEEN THE NRN AND SOUTHERN STREAMS WITH OBVIOUS
BIG IMPLICATIONS. NO WAY OF KNOWING THE CORRECT SOLUTION AT THIS
JUNCTURE...BUT WILL HAVE LOWER END SNOW CHANCES ON TUESDAY FOR NOW.
ANOTHER SHOT FOR A STORM SYSTEM MAY COME WEDNESDAY NIGHT THROUGH
THURSDAY WITH THE POTENTIAL FOR YET ANOTHER STORM TO SPIN UP OFF THE
GULF AND LIFT NORTHWARD THROUGH THE EASTERN CONUS. AGAIN...BIG
DIFFERENCES ON THE TIME/TRACK OF THAT STORM (IF IT OCCURS AT ALL).
BUT WILL CARRY CHANCE POPS FOR SNOW DURING THAT TIME.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 638 PM EST THU DEC 20 2012
CHANGEOVER TO ALL SNOW HAS OCCURRED AT MBL AND TVC....WITH SNOW AT
PLN AND RAIN ONGOING AT APN. OVERNIGHT...LOW PRESSURE OVER
SOUTHERN LAKE MICHIGAN WILL LIFT NORTH AND EAST...WITH MODERATE
TO OCCASIONALLY HEAVY SNOW AT TVC/MBL/PLN FOR THE BALANCE OF THE
NIGHT WITH VLIFR-LIFR CONDITIONS. THESE CONDITIONS WILL REACH APN
AFTER ABOUT 9Z AS RAIN CHANGES OVER TO SNOW. TOWARDS DAYBREAK AND
THR0UGH THE DAY ON FRIDAY...SNOW WILL TAPER TO LAKE EFFECT SNOW
SHOWERS THAT WILL IMPACT PRIMARILY TVC AND APN...WITH
NORTHWESTERLY WINDS INCREASING TO 25G35KTS...WHICH WILL CAUSE
BLOWING SNOW AT ALL SITES. EXPECT RESTRICTIONS TO TRANSITION TO
MORE MVFR BY FRIDAY AFTERNOON DUE TO BLSN AND CIGS.
&&
.MARINE...
ISSUED AT 414 PM EST THU DEC 20 2012
MAJOR WINTER STORM LIFTING NE INTO THE GREAT LAKES THROUGH
TONIGHT...BEFORE DEPARTING FRIDAY. OVERLAKE INSTABILITY WITH
EASTERLY WINDS AT 20-35KTS TO DEVELOP AS MODERATE TO HEAVY SNOWS
(MIXED WITH OR ALL RAIN ACROSS LAKE HURON). THE SNOWS WILL BE
INCREASINGLY INTENSE THIS EVENING. WINDS WILL DECREASE SOME ACROSS A
GOOD CHUNK OF THE NEARSHORES THIS EVENING...BUT THEN RAMP BACK UP
AGAIN LATE TONIGHT AND FRIDAY WITH COLD ADVECTION FOLLOWING THE
DEPARTING SFC LOW PRESSURE. WINDS WILL GUST AS HIGH AS
50KTS...RESULTING IN STORM FORCE WINDS FOR THE NW LOWER NEARSHORES.
SOLID GALES ALL OTHER MARINE AREAS. GRADIENT GRADUALLY LOOSENS UP
OVER THE WEEKEND...BUT GALES AND OBVIOUSLY CHOPPY WAVES WILL PERSIST
THROUGH FRIDAY NIGHT.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 7 PM EST FRIDAY FOR MIZ008-015>029-
031>034.
WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ030-035-041.
LH...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LHZ345>349.
LM...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LMZ341.
STORM WARNING FROM 10 PM THIS EVENING TO 7 PM EST FRIDAY FOR
LMZ323-342-344>346.
GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LMZ323-342-344>346.
GALE WARNING FROM 7 PM FRIDAY TO 7 AM EST SATURDAY FOR LMZ323-
342-344>346.
LS...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LSZ321-322.
&&
$$
UPDATE...ARNOTT
SYNOPSIS...TL
SHORT TERM...AS
LONG TERM...BA
AVIATION...JA
MARINE...AS
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 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 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 RALEIGH NC
650 PM EST THU DEC 20 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL SWEEP ACROSS THE REGION TONIGHT. BEHIND THE
FRONT...A STRONG STORM SYSTEM OVER THE EASTERN GREAT LAKES WILL
INFLUENCE OUR WEATHER ON FRIDAY. HIGH PRESSURE BUILDS IN FOR
SATURDAY AND SUNDAY...WITH LOW PRESSURE AND INCREASING MOISTURE
RETURNING BY CHRISTMAS DAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 235 PM THURSDAY...
STRONG LOW PRESSURE MOVING INTO THE UPPER GREAT LAKES WITH VERY GOOD
TEMPERATURE AND MOISTURE ADVECTION STARTING TO TAKE PLACE ACROSS
SOUTH CAROLINA...TOWARD THE NORTH CAROLINA BORDER WHERE WINDS ARE
FINALLY STARTING TO SHOW A GUSTY CHARACTER. WEAK BOUNDARY EVIDENT
WITH BACKING WINDS NEAR AND JUST NORTHWEST OF THE TRIAD...IN
VICINITY OF KINT...AND AS THE RAIN MOVES IN THIS COULD BECOME A
WEDGE FRONT ALONG WHICH THE TRIPLE POINT MOVES NEAR THIS EVENING.
OVERALL EXPECTATIONS HAVE NOT CHANGED MUCH WITH THIS FORECAST
PACKAGE...WITH WIDESPREAD SHOWERS EXPECTED TO PUSH ACROSS CENTRAL
NORTH CAROLINA THIS EVENING. STILL HAVE THE MENTION OF THUNDER IN
AREA-WIDE...ALTHOUGH THE GREATEST POTENTIAL COULD BE...AGAIN...
ALONG AND NEAR A LINE FROM ABOUT WADESBORO AND ALBEMARLE NORTHEAST
THROUGH THE TRIANGLE TO NEAR KIXA AND KRWI. IT IS IN THIS AREA WHERE
THE DEEPER MOISTURE SHOULD END UP...AND LOOKING AT SOME LOW-LEVEL
MOISTURE PARAMETERS FOR THE LATE AFTERNOON AND EVENING REALLY LIKE
THE LATEST RUC DEPICTION OF THE POTENTIAL OF SOME LOWER 60S DEW
POINTS ADVECTING INTO THAT AREA VERY LATE THIS AFTERNOON AND INTO
THIS EVENING IN ADVANCE OF THE FRONT. IF THIS HOLDS...QUITE POSSIBLE
THAT HIGH TEMPERATURES COULD BE REALIZED AS LATE AS AROUND OR JUST
AFTER SUNSET...AND WILL ATTEMPT TO ACCOUNT FOR SOME OF THIS FINE
DETAIL IN THE GRIDDED FORECAST.
GFS AND NAM SOUNDINGS REMAIN MARGINAL WHEN IT COMES TO INSTABILITY...
BUT THE LATEST RUC SOUNDINGS...PARTICULARLY TOWARD KFAY...PAINT A
MARGINALLY OMINOUS PICTURE. LAPSE RATES THERE...IF THE RUC VERIFIES
EXACTLY...ARE NEAR MOIST ADIABATIC...AND GIVEN THE LIFT AND SHEAR...
RELATIVE TO THE REST OF CENTRAL NORTH CAROLINA THE BETTER POTENTIAL
FOR NEAR-SURFACE BASED ROTATING LOW-TOPPED STORMS WOULD BE AROUND
THERE. THIS COINCIDES WITH THE LATEST SPC DAY ONE OUTLOOK...AND
NEARER THE LOCAL WRF MODEL DEPICTION THE MAXIMUM UPDRAFT HELICITY.
WHAT STILL APPEARS MOST LIKELY IS NUMEROUS CELLS WITH MID-LEVEL
ROTATION...STRONG WINDS WHICH MAY APPROACH ADVISORY CRITERIA IN THE
STRONG THICKNESS PACKING AS THE DRY SLOT MOVES IN IMMEDIATELY BEHIND
THE SHOWERS AND THE FRONT...A MODEST POTENTIAL FOR SEVERE
STRAIGHT-LINE WINDS IN THE RICHER DEW POINT AIR...AND SOME POTENTIAL
FOR AN ISOLATED TORNADO KEYING ON THE AREA MAINLY EAST OF THE LINE
FROM KAFP TO KRWI. FOR NOW...THINK THAT THE LONGEVITY OF ADVISORY
CRITERIA WINDS MAY BE BRIEF AND NOTED CLOSE TO DEEP CONVECTION...
WITH BUFR SOUNDINGS AND GUIDANCE ACTUALLY SHOWING SOME MODEST
DECREASE TO WIND GUST POTENTIAL LATE. AS A RESULT...FOR NOW OPTED
NOT TO ISSUE A WIND ADVISORY OVERNIGHT...THOUGH BRIEF CONDITIONS MAY
WARRANT A SHORT-FUSED STATEMENT AT LEAST.
THOUGHTS THEN SHIFT TO THE POTENTIAL FOR VERY WINDY CONDITIONS IN
THE TIGHT GRADIENT FRIDAY. BUFR SOUNDINGS FROM BOTH THE NAM AND THE
GFS SUGGEST A HIGH PROBABILITY OF LOW-LEVEL WIND ADVISORY CRITERIA
FRIDAY...WITH POTENTIAL MIXING TO 40KT. HOWEVER...AS THE MID-LEVEL
TROUGH MOVES OVERHEAD...THE GFS IN PARTICULAR FORECASTS ENOUGH
MOISTURE TO PROVIDE FOR AREAS OF HIGH-LEVEL SC OR LOW-LEVEL AC
DURING THE LATE MORNING INTO THE AFTERNOON. IF CLOUDS ARE REALIZED A
LITTLE MORE THAN FORECAST...THIS COULD LIMIT MIXING POTENTIAL. FOR
THIS FORECAST WILL OPT TO ISSUE A WIND ADVISORY FOR FRIDAY...WITH A
FOCUS ON THE LATE MORNING THROUGH THE AFTERNOON...AS EVEN IF
CONDITIONS ARE ON THE MARGINS THERE COULD BE IMPACT AS IT SEEMS LIKE
IT HAS BEEN A WHILE SINCE CENTRAL NORTH CAROLINA HAS EXPERIENCED
WINDS EVEN CLOSE TO ADVISORY CRITERIA.
FRIDAY NIGHT...UNDER POSSIBLE LINGERING CLOUDS...ANTICIPATE THE
WINDS RELAXING RELATIVELY QUICKLY BUT STILL WITH A GUSTY CHARACTER
AS THE TROUGH AXIS DEPARTS AND THE GRADIENT REMAINS TIGHTER THAN
USUAL. AFTER OVERNIGHT LOWS TONIGHT FALLING TO THE LOWER TO MID 30S
NEAR THE YADKIN RIVER AND TO NEAR 40 TOWARD INTERSTATE 95...HIGHS ON
FRIDAY SHOULD RANGE FROM THE MID 40S TO AROUND 50...ACTUALLY FAIRLY
CLOSE TO OR JUST A CATEGORY BELOW NORMAL. LOWS FRIDAY NIGHT 25 TO
30...ANTICIPATING ENOUGH MIXING AND A FEW CLOUDS TO KEEP
TEMPERATURES FROM FALLING TOO FAR.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 255 PM THURSDAY...
SAT AND SAT NIGHT: IT WILL REMAIN RATHER BRISK IN CONTINUED
CAA...WITH BUFR MIXED LAYER WINDS SUGGESTIVE OF NORTHWESTERLY WINDS
GUSTING TO BETWEEN 25-30 KTS...HIGHEST NORTHEAST. THESE WINDS...IN
CONJUNCTION WITH DEWPOINTS IN THE TEENS AND CONSEQUENT RH AOB 25
PERCENT MAY RESULT IN FIRE WEATHER CONCERNS. WHILE SKIES SHOULD
REMAIN CLEAR OVERALL...THERE REMAINS A STRONG SIGNAL FOR OROGRAPHIC
CIRRUS OVER THE MIDDLE ATLANTIC FOOTHILLS/WESTERN PIEDMONT SAT
NIGHT. PREVIOUSLY FORECAST UPPER 40S TO LOWER-MIDDLE 50S REMAIN ON
TARGET. WINDS SHOULD DIMINISH OVERNIGHT OVER ALL BUT PERHAPS THE
NORTHEAST PIEDMONT AND NORTHERN COASTAL PLAIN...AS HIGH PRESSURE
OVER THE GULF COAST STATES RIDGES NORTHWARD. LOWS IN THE MIDDLE TO
UPPER 20S...TO AROUND 30 DEGREES OVER THE NW PIEDMONT IF OPAQUE
CIRRUS MATERIALIZES THERE.
A NORTHERN STREAM COLD FRONT WILL SETTLE SLOWLY SOUTHWARD TOWARD THE
VA STATE LINE BY SUNDAY NIGHT...WHERE IT WILL LIKELY STALL THERE IN
ADVANCE OF A LEAD S/W TROUGH AND SURFACE FRONTAL WAVE APPROACHING
FROM THE PLAINS. TRANQUIL AND GENERALLY MOSTLY CLEAR CONDITIONS...
ASIDE FROM CIRRUS...SHOULD ACCORDINGLY CONTINUE. MINIMALLY MILDER
HIGHS AND LESS CHILLY LOWS...IN THE LOWER TO MIDDLE 50S AND
30S...RESPECTIVELY.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 317 PM THURSDAY...
BECOMING WET COURTESY OF A POWERFUL EASTERN US STORM BY MID-WEEK.
WHILE MEDIUM RANGE GUIDANCE REMAINS IN GENERAL AGREEMENT WITH THE
HEMISPHERIC FLOW...INDIVIDUAL MODEL SOLUTIONS REGARDING THE TRACK OF
THE EASTERN US CYCLONE STILL VARY...AND ARE HIGHLY SENSITIVE TO
SUBTLETIES OF LOCATION OF BOTH HIGH LATITUDE BLOCKING FORECAST TO
DEVELOP INVOF BAFFIN ISLAND...AND AN ELONGATED VORTEX ACROSS
SOUTHERN CANADA. THESE SUBTLETIES...AND THE AMPLITUDE AND DEGREE
OF PHASING OF THE S/W TROUGHS EMBEDDED WITHIN A STRONG PACIFIC JET
ALL CAST FORECAST UNCERTAINTY...BUT THE PROBABILITY OF A SOAKING
RAIN MID-WEEK REMAINS HIGH...WITH THE THREAT OF WINTRY WEATHER STILL
LIKELY TO HOLD TO THE NORTH AND WEST OF EVEN THE FAVORED NC PIEDMONT
DAMMING REGION.
A LEAD S/W TROUGH WILL PIVOT FROM THE CENTRAL PLAINS TO THE GREAT
LAKES AND BE ACCOMPANIED BY A RELATIVELY WEAK SURFACE FRONTAL WAVE
THAT WILL MIGRATE THROUGH THE MIDDLE ATLANTIC STATES MON-MON NIGHT.
A PRECEDING WARM CONVEYOR/ISENTROPICALLY-DRIVEN CLOUD BAND AND
EMBEDDED SCATTERED SHOWERS WILL SPREAD EASTWARD ACROSS CENTRAL NC
MON AFTERNOON AND OVERNIGHT...BUT THE DEPTH OF THE ASSOCIATED
SATURATION IS FORECAST TO BE SHALLOWER/WARMER THAN WHAT IT APPEARED
24 HOURS AGO...SO PRECIPITATION AMOUNTS SHOULD BE GENERALLY A TENTH
OF AN INCH OR LESS...AND ONLY SCATTERED ABOUT.
THE TRAILING FRONT WILL THEN STALL OVER NC...IN ADVANCE OF THE MUCH
STRONGER WAVE FORECAST TO LIFT NORTHEASTWARD FROM THE GOM. THIS
BOUNDARY WILL FOCUS PRECIPITATION TUE-TUE NIGHT...CULMINATING IN
WIDESPREAD RAIN AS THE LOW TRACKS NORTH ON WED. IT STILL APPEARS
THAT ENOUGH DAMMING WILL HOLD EAST OF THE APPALACHIANS TO INDUCE
MILLER TYPE-B REDEVELOPMENT EAST OF THE INITIAL WAVE LIFTING OUT OF
THE GOM...BUT THE DEGREE OF THIS SEPARATION...AND DAMMING IN
BETWEEN...WILL BE A FUNCTION OF HOW THE AFOREMENTIONED HIGH-LATITUDE
BLOCKING AND CAD-SUPPORTING CONFLUENCE ALOFT EVOLVE. FAVOR AT THIS
TIME A MORE DOMINANT CONFLUENT REGIME ALOFT AND STRONGER CAD...WHICH
SUGGESTS THE NORTHWEST PIEDMONT SHOULD HOLD IN THE 40S ON WED...
RANGING TO LOWER-MIDDLE 60S OVER THE COASTAL PLAIN. MUCH COOLER AND
DRIER CONDITIONS WILL PREVAIL IN THE WAKE OF THE STORM BY WED NIGHT
AND ESPECIALLY THU.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AS OF 650 PM THURSDAY...
MVFR-IFR CEILINGS AND MVFR VISIBILITY IN SHOWERS WILL OVERSPREAD AND
PERSIST ACROSS CENTRAL NC THIS EVENING AS A STRONG COLD FRONT
APPROACHES AND TRAVERSES THE REGION. PRECEDING THE FRONT SE-S WINDS
WILL GUSTS UP TO 25 MPH. BEHIND THE FRONT...WLY WINDS WILL GUSTS
30-35 MPH. THERE IS A SLIGHT RISK FOR SEVERE STORMS IN VICINITY OF
KFAY AND KRWI BETWEEN 9 PM AND MIDNIGHT. DUE TO LIMITED NEAR SURFACE
INSTABILITY...WILL OMIT THE MENTION OF THUNDER IN THE TAF FOR KFAY
AND KRWI.
FRIDAY...MIXING WILL RESULT IN GUSTS TO AROUND 35KT. IN THE COLD AIR
ASSOCIATED WITH THE MID-LEVEL TROUGH OF LOW PRESSURE...SOME VFR
LEVEL CLOUDS ARE LIKELY WITH A HIGHER CONCENTRATION OF CLOUDS ACROSS
THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN. THESE CLOUDS COULD
LIMIT THE POTENTIAL GUSTS SOMEWHAT AT THE SURFACE...BUT EVEN
SO...WINDS WITHIN 2500FT OF THE SURFACE SHOULD EASILY APPROACH 40KT.
A GRADUAL DECREASE IN WINDS OCCURS FRIDAY NIGHT INTO SATURDAY. AHEAD
OF A WEAKER LOW PRESSURE SYSTEM...MOISTURE SHOULD START TO INCREASE
ONCE AGAIN BY EARLY NEXT WEEK. AS A RESULT...ADVERSE AVIATION
CONDITIONS...MAINLY IN LOW CLOUDS...COULD RETURN AS EARLY AS LATE IN
THE DAY MONDAY AND CONTINUING INTO TUESDAY...ESPECIALLY TOWARD THE
TRIAD LATE MONDAY INTO MONDAY NIGHT.
&&
.FIRE WEATHER...
AS OF 410 PM THURSDAY...
BEHIND A POWERFUL CYCLONE FORECAST TO MIGRATE FROM THE UPPER MIDWEST
TO THE NORTHEAST...NORTHWEST WINDS WILL REMAIN STRONG -- IN THE
15-20 MPH RANGE WITH GUSTS IN THE UPPER 20S TO LOWER 30S MPH -- ON
SATURDAY. IN ADDITION...MUCH DRIER AIR CHARACTERIZED BY SURFACE
DEWPOINTS IN THE TEENS...WILL SUPPORT AFTERNOON HUMIDITY VALUES OF
20-25 PERCENT. THESE CONDITIONS MAY RESULT IN INCREASED FIRE
DANGER...AND FURTHER COORDINATION WITH THE NCFS REGARDING THIS
SCENARIO WILL TAKE PLACE ON FRI.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 9 AM TO 7 PM EST FRIDAY FOR NCZ007>011-
021>028-038>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...WSS
NEAR TERM...DJF
SHORT TERM...MWS
LONG TERM....MWS
AVIATION...WSS/DJF
FIRE WEATHER...MWS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
804 PM EST THU DEC 20 2012
.SYNOPSIS...
STRONG COLD FRONT PLOWS THROUGH THIS EVENING. SNOW SHOWERS BEHIND
LOW PRESSURE TONIGHT INTO SATURDAY. HIGH PRESSURE PASSES SUNDAY. LOW
PRESSURE CHRISTMAS EVE AND AGAIN MIDWEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
8 PM UPDATE...NO MAJOR CHANGES TO THE FORECAST THIS
EVENING...HOWEVER...DID ELECT TO ISSUE AN SPS THIS EVENING FOR
RANDOLPH...NICHOLAS...WEBSTER...AND POCAHONTAS COUNTIES...AS A FEW
REPORTS OF SLEET...AND ISOLD PATCHES OF SLICK CONDITIONS AT
ELEVATIONS ABOVE 3000 FEET WERE REPORTED.
COLD FRONT AT 01Z STARTING TO ENTER WESTERN ZONES...WITH WINDS
BEHIND THE FRONT GUSTING IN THE UPPER 30S TO LOWER 40S BEHIND THE
FRONT. PRECIPITATION IN INDIANA AND CENTRAL KENTUCKY HAS ALREADY
CHANGED TO SNOW...AND EXPECT A GRADUAL CHANGE OVER HERE AFTER
MIDNIGHT.
DID ELECT TO ADD ATHENS...MEIGS...AND JACKSON COUNTIES TO THE
WINTER WEATHER ADVISORY...IN EFFECT FROM 1 AM FRIDAY THROUGH 10 PM
FRIDAY. BASED THIS ON BOTH MODEL TRENDS AS WELL AS THE INHERITED
FORECAST...WHICH ACTUALLY IN ATHENS COUNTY HAS MORE SNOWFALL
PREDICTED IN A 12 HOUR TIME PERIOD THAN WE HAVE FOR PERRY AND
MORGAN COUNTIES...WHICH HAVE THE SAME SNOWFALL CRITERIA OF 2
INCHES IN 12 HOURS. WENT AHEAD AND ADDED JACKSON COUNTY WV FOR
IMPACT...AS I-77 RUNS THROUGH THIS COUNTY...AND TO COVER FOR
POTENTIAL TRAVEL ON FRIDAY FOR THE HOLIDAY WEEKEND.
PREVIOUS DISCUSSION FOLLOWS...
INITIAL PRECIP FROM THIS MORNING HAS MOSTLY LIFTED TO THE
NORTH...WITH THE NEXT BATCH ALREADY WELL INTO WESTERN CWA. HAVE
GOTTEN SOME REPORTS OF LIGHT SNOW FALLING ACROSS HIGHER TERRAIN IN
NORTHERN WV MOUNTAINS. THIS IS TIED TO A SMALL COLD POOL STILL IN
PLACE...BUT AS WINDS SHIFT AROUND TO MORE S THEN SW...THIS COLD POOL
SHOULD BE CLEARED OUT WITH A RETURN TO RAIN UNTIL TONIGHT. ALL THIS
CURRENT PRECIP IS STILL WELL PRE-FRONTAL...WITH THE COLD FRONT
CURRENTLY RUNNING FROM THE LOW IN NORTHEASTERN IL...THROUGH SW
IN...AND CENTRAL KY/TN. AT 19Z...FRONT SHOWING UP WELL ON RADAR IN
KY...RUNNING FROM ROUGHLY KGLW TO KSDF. PRE-FRONTAL PRECIP SHOULD
WRAP UP BEFORE THE FRONT...WITH A THIN LINE OF SHOWERS RIGHT ALONG
THE FRONT. IN GENERAL PRE-FRONTAL WIND GUSTS HAVE BEEN 20-35
KTS...WITH THE STRONGER GUSTS BEHIND THE FRONT. CONSIDERED STARTING
WIND ADVISORY EARLIER...BUT NOT SEEING ANY OBS WITH CRITERIA OPTED
TO LEAVE AS IS...WAITING FOR THOSE STRONGER GUSTS BEHIND THE FRONT.
MODELS STILL SHOWING A PRETTY GOOD DRY SLOT BEHIND THE FRONT...SO
TRANSITION AN AREA OF LOW SLIGHT CHANCE POPS ACROSS THE CWA FROM
ABOUT 03Z TO 06Z...THEN HAVE WRAP AROUND MOISTURE SURGING BACK IN.
INITIALLY...COLD AIR WILL STILL BE LAGGING BEHIND THE FRONT OF THE
PRECIP SHIELD...SO WRAP AROUND SHOULD START AS RAIN SHOWERS. THEN AS
COLD AIR SURGES IN WILL SEE A TRANSITION FROM RAIN TO SNOW IN THE
MOUNTAINS AND ALSO MOVING ACROSS THE LOWLANDS FROM WEST TO EAST.
WITH THE WRAP AROUND...COORDINATED WITH SHORT TERM FORECASTER ON A
WINTER WEATHER ADVISORY STARTING AT 06Z FROM PERRY COUNTY OHIO EAST
TO THE ALREADY IN PLACE ADVISORY IN WV.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
SIGNIFICANT UPSLOPE SNOW EVENT IMPACTS THE AREA THIS PERIOD.
WRAP AROUND ARRIVES FROM THE W RIGHT AT THE START OF THE PERIOD.
MODELS INCLUDING NEAR TERM HIRES SUGGESTS THIS IMPACTS MID SE OHIO
BEFORE LIFTING THROUGH FAR NORTHERN WV AND ON INTO PA FRI. GENERAL
UPSLOPE FLOW ALSO SETS UP RIGHT AT THE START OF THE PERIOD AND
PERSISTS INTO SAT BEFORE WINDING DOWN SAT AFTERNOON AND EVENING.
AS COMMA / WRAP AROUND TAIL LIFTS OUT FRI...SECOND PLUME OFF LAKE
MICHIGAN MAY SET UP FOR A TIME...PERHAPS A LITTLE S OF WHERE THE
INITIAL WRAP AROUND OCCURS. IT THEN WILL EITHER DRIFT INTO THE SAME
AREA AFFECTED BY THE INITIAL RAP AROUND OR SIMPLY FADE IN PLACE LATE
FRI.
THE WESTERN SLOPES OF THE MOUNTAINS EXPERIENCE STRONG UPSLOPE
WINDS AS THE HIGH SPEEDS SOMEWHAT MAKE UP THE THE LESS THAN
PERPENDICULAR ANGLE PER W FLOW. AIR MASS IS COLD ENOUGH AND
MOISTURE DEPTH GREAT ENOUGH TO EASILY SUPPORT FAVORED DENDRITIC
GROWTH MOST OF THE TIME AND THUS SIGNIFICANT SNOW ACCUMULATIONS.
LEFT WARNINGS AND ADVISORIES AS IS EXCEPT TO EXPAND THE ADVISORY W
ACROSS OUR FAR NORTHERN WV COUNTIES AND ON BACK THROUGH MID SE OHIO
WHERE INITIAL WRAP AROUND SETS UP. SNOW AMOUNTS FARTHER S AND W ARE
ONLY A LITTLE LOWER THOUGH AND REMAINING COUNTIES NOT WARNED OR
ADVISED WILL STILL HAVE WINTRY IMPACTS.
ENTERTAINED BLIZZARD WARNINGS NORTHERN MOUNTAINS BUT RECKONED 3 HRS
OF 1/4SM SN BLSN WOULD BE HARD TO REALIZE SAVE MAYBE FOR THE HIGHEST
WINDWARD SLOPES. SIMILAR DEAL ON HIGH WIND WARNING AS ONLY A FEW
LOCATIONS WILL EXPERIENCE BRIEF GUSTS PAST 50 KTS. 60-65 KTS FLOW
SHOWN AT H85 FRI NT PER NOCTURNAL JET BUT THIS WILL NOT BE REALIZED
AT SURFACE...CLOSE ONLY ACROSS THE HIGHEST EXPOSED RIDGES.
MAINTAINED AREA WIDE WIND ADVISORY.
SNOWS AND WINDS WIND DOWN AND CLEARING COMMENCES SW TO NE SAT MIDDAY
THROUGH SAT NT AS HEIGHTS RISE AND WEAK LOW-MID LEVEL WARM ADVECTION
COMMENCES.
USED A HIRES/NAM/MOS COMBINATION ON TEMPERATURES THROUGH FRI NT
WHICH REFLECTS CORE OF THE COLD AIR CROSSING FRI MIDDAY AND
AFTERNOON. HAVE SUBFREEZING TEMPERATURES EVERYWHERE DURING THAT
TIME WHICH...TOGETHER WITH THE WINTER SOLSTICE...WILL FAVOR DAYTIME
ACCUMULATIONS. TEMPERATURES SAT AND SAT NT NEEDED NOTHING MORE THAN
MINOR EDITS IN LIGHT OF LATEST OF GUIDANCE / ON LOW SIDE / ...AS
SYSTEM SLOWLY PULLS OUT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
THIS WILL BE A VERY UNSETTLED WEATHER PATTERN WITH CHANGEABLE
TEMPERATURES...IN WHICH TWO LOW PRESSURE SYSTEMS WILL AFFECT THE
AREA. THE MODELS ARE NOT IN GOOD AGREEMENT WITH THE STRENGTH AND
TIMING OF THESE SYSTEMS. RELYING MORE ON THE ENSEMBLES TO MITIGATE
THE DIFFERENCES WILL BE THE WAY TO GO...SO HPC GUIDANCE WITH THE
BLEND OF MODEL DATA WAS FOLLOWED CLOSELY.
EXPECT A DRY AND CHILLY DAY SUNDAY UNDER HIGH PRESSURE.
THE FIRST SYSTEM MONDAY AND MONDAY NIGHT WILL BE ON THE FLAT SIDE
WITH A WEAK LOW PRESSURE SYSTEM TRACKING ACROSS ALONG THE OHIO
RIVER. THIS WILL PUT US ON THE MILD SIDE WITH MAINLY RAIN
MONDAY...EXCEPT POSSIBLY SNOW IN THE NORTHERN
MOUNTAINS...TRANSITIONING TO SOME LIGHT SNOW ON THE BACK SIDE ACROSS
THE NORTH MONDAY NIGHT.
KEPT LOW LIQUID POPS SOUTH TUESDAY WITH FRONTAL SYSTEM TO OUR
SOUTH...BUT MOST OF THE AREA WILL BE DRY AND CHILLY WITH WEAK HIGH
PRESSURE.
SECOND SYSTEM LOOKS TO BE MUCH STRONGER AS IT TRACKS NORTHEASTWARD
TO THE WEST OF OUR AREA...BRINGING A GOOD SHOT OF MILD AIR AND
SIGNIFICANT RAIN WEDNESDAY. AS THE LOW PASSES WEDNESDAY
NIGHT...EXPECT A GENERAL TRANSITION TO SNOW WEDNESDAY NIGHT INTO
THURSDAY MORNING.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
MAINLY VFR CONDITIONS OUTSIDE OF RAIN SHOWERS AND AREAS OF MIXED
PRECIPITATION OVER HIGHER TERRAIN. EXPECT BRIEF MVFR CONDITIONS IN
PRECIPITATION. DRY SLOW WILL MOVE INTO AREA FROM WEST TO EAST
AFTER 02Z...WITH A BRIEF PERIOD OF MAINLY VFR CONDITIONS EXPECTED
UNTIL LIGHT SNOW SHOWERS BEGIN TO DEVELOP AFTER 06Z. EXPECT
DEVELOPMENT OF WIDESPREAD MVFR AND LOCAL IFR CONDITIONS AFTER
06Z...AND LINGERING FOR MUCH OF THE TAF PERIOD. CONDITIONS ACROSS
THE HIGHER TERRAIN MAY BE LIFR/VLIFR AT TIMES ON FRIDAY IN HEAVIER
SNOW SHOWERS.
IN ADDITION...VERY STRONG WINDS WILL DEVELOP BEHIND THE COLD
FRONT...WHICH AT 01Z IS ENTERING EASTERN KENTUCKY...SOUTHWEST
VA...AND SOUTHERN WV. EXPECT WIND GUSTS OF UP TO 40 KTS ACROSS THE
LOWLANDS...AND UP TO 50 KTS ACROSS THE HIGHER TERRAIN BEHIND THE
FRONTAL PASSAGE OVERNIGHT THURSDAY INTO FRIDAY.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING OF PRECIPITATION AND LOWER CLOUDS COULD
VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE FRI
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06
CRW CONSISTENCY M H H M H M L L L M M M
HTS CONSISTENCY H H H H H H L L L L L M
BKW CONSISTENCY H H H H M M L L M M M M
EKN CONSISTENCY M H M H H M L M M M M M
PKB CONSISTENCY H H H H H M L L L M M M
CKB CONSISTENCY M M M H H H M L L M M M
AFTER 00Z SATURDAY...
IFR POSSIBLE INTO SATURDAY DUE TO SNOW SHOWERS...ESPECIALLY IN
THE MOUNTAINS. IFR CONDITIONS MAY LINGER ACROSS THE HIGHER TERRAIN
INTO SUNDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY UNTIL 10 PM EST FRIDAY FOR WVZ005>011-013>020-
024>034-039-040.
WIND ADVISORY UNTIL 7 AM EST SATURDAY FOR WVZ035>038-046-047.
WINTER STORM WARNING FROM 1 AM FRIDAY TO 2 PM EST SATURDAY FOR
WVZ036>038-046-047.
WINTER WEATHER ADVISORY FROM 1 AM FRIDAY TO 2 PM EST SATURDAY
FOR WVZ027-028-035-039-040.
WINTER WEATHER ADVISORY FROM 1 AM FRIDAY TO 7 AM EST SATURDAY
FOR WVZ015-016-018-025-026-029>034.
WINTER WEATHER ADVISORY FROM 1 AM TO 10 PM EST FRIDAY FOR
WVZ008>011-017-019-020.
OH...WIND ADVISORY UNTIL 10 PM EST FRIDAY FOR OHZ066-067-075-076-
083>087.
WINTER WEATHER ADVISORY FROM 1 AM TO 10 PM EST FRIDAY FOR
OHZ066-067-075-076-085.
KY...WIND ADVISORY UNTIL 10 PM EST FRIDAY FOR KYZ101>103-105.
VA...WIND ADVISORY UNTIL 10 PM EST FRIDAY FOR VAZ003-004.
&&
$$
SYNOPSIS...TRM/JMV/MZ
NEAR TERM...MZ/SL
SHORT TERM...TRM
LONG TERM...JMV
AVIATION...SL
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
AREA FORECAST DISCUSSION
NWS SPOKANE WA
553 PM PST Thu Dec 20 2012
.SYNOPSIS...
Unsettled weather will persist into Friday with occasional light
rain or snow expected. Another storm will likely impact the Inland
Northwest on Saturday with widespread light to moderate snow
accumulations expected north of I-90. Another weaker storm is
possible on or about Monday. Christmas Day looks mostly dry but
another storm could bring a chance for snow late in the day or
Christmas night.
&&
.DISCUSSION...
Update: Radar and satellite imagery as of 530 pm indicated a weak
cold front stretching from Central Washington south into Central
Oregon. Ahead of this front downslope south-southeast winds off
the Blue and Wallowa Mountains as well as the Clearwaters
continues to keep the boundary layer dry over the Columbia Basin,
Spokane area, Palouse, Lewiston area, and Camas Prairie. As the
front continues to slowly move east it will take some time for the
atmosphere to moisten up and thus the evening forecast has been
revised to lower precipitation chances for most areas south of a
line from Colville to Sandpoint. North of this line areas of snow
will continue into the evening where a winter storm warning
remains in effect. Pops were also adjusted downward along the East
Slopes of the Cascades where web cameras show most of the snow
confined to near the Cascade crest. As the front moves east
overnight models and the latest HRRR show light snow increasing
mainly over North Idaho, with the dry boundary layer over the
Spokane and Pullman areas resulting in only a chance for light
snow with nothing more than a dusting expected. JW
&&
.AVIATION...
00Z TAFS : Moisture continues to stream in from the south affecting
most TAF sites tonight with light rain/snow and MVFR/IFR ceilings and
visibilities. This will continue to be a threat at KEAT, KMWH, KGEG,
KSFF, and KCOE after about 03Z. Drier air with southeast wind into
KLWS will result in higher VFR CIGS and less chances for
precipitation. The same is true for KPUW but MVFR conditions are
forecast to develop after 06Z. Conditions will generally
deteriorate after 03Z tonight in the aforementioned affected areas
but improve after 18Z to at least MVFR conditions. TC
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 30 38 30 37 26 35 / 40 50 60 80 60 40
Coeur d`Alene 30 38 31 38 27 35 / 70 60 60 80 80 50
Pullman 31 41 33 39 29 37 / 50 20 40 60 50 30
Lewiston 35 45 36 44 32 42 / 20 20 30 50 40 30
Colville 32 36 31 38 27 35 / 50 60 70 90 60 50
Sandpoint 32 36 31 36 27 34 / 80 80 80 90 90 60
Kellogg 31 37 28 37 27 32 / 70 60 60 80 80 60
Moses Lake 28 38 30 38 25 36 / 10 30 50 60 20 20
Wenatchee 25 34 28 36 25 34 / 10 60 60 70 30 40
Omak 24 36 27 35 23 32 / 20 60 60 90 30 50
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning until Midnight PST tonight for Northern
Panhandle.
WA...Winter Storm Warning until Midnight PST tonight for Northeast
Mountains.
&&
$$
AREA FORECAST DISCUSSION
NWS TAUNTON MA
411 AM EST FRI DEC 21 2012
.SYNOPSIS...
LOW PRESSURE AND ITS ATTENDING OCCLUDED FRONT WILL BRING A
PERIOD OF HEAVY RAIN AND STRONG WINDS TO THE REGION TODAY. COLDER
TEMPS WILL FOLLOW FOR THE WEEKEND INTO EARLY NEXT WEEK. A WEAK
STORM COULD BRING SOME SNOW AND/OR RAIN ON CHRISTMAS DAY. A
STRONGER STORM MAY AFFECT NEW ENGLAND LATE WED INTO THU.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SNOW IN THE DISTANT INTERIOR HAS ACCUMULATED 1-2 INCHES. IT IS
STILL SNOWING ACROSS WESTERN AND NORTHERN MA INTO S NH WITH TEMPS
32-34 DEGREES. HOWEVER...LOW LEVEL WARMING WILL RESULT IN A QUICK
CHANGEOVER TO RAIN THROUGH 6 AM. ADDITIONAL ACCUMULATION UP TO AN
INCH IS POSSIBLE.
A PERIOD OF STRONG WINDS AND HEAVY RAIN WILL MOVE ACROSS SNE
TODAY AS AN ANOMALOUS LOW LEVEL JET AHEAD OF A STRONG OCCLUDED
FRONT SWEEPS ACROSS THE REGION. THIS SYSTEM IS RATHER PROGRESSIVE
SO THE WORST OF THE WIND AND RAIN WILL LIKELY BE CONFINED TO A 3-4
HOUR WINDOW...12-16Z IN THE WEST AND 16-20Z EASTERN NEW ENG.
RAINFALL/FLOOD POTENTIAL...
STRONG LOW LEVEL JET 3-4SD AND +2SD PWAT ANOMALY WILL BRING A
PERIOD OF HEAVY RAIN TO SNE. HOWEVER...THIS SYSTEM WILL BE QUICK
MOVING LIMITING THE DURATION OF HEAVY RAIN IN ANY ONE LOCATION.
NAM IS THE MOST ROBUST WITH ELEVATED INSTABILITY PARAMETERS AND
SUGGEST POTENTIAL FOR SOME CONVECTION/THUNDER...AND HRRR IS
INDICATING A FINE LINE OF CONVECTION MOVING THROUGH.
HOWEVER...GFS AND ECMWF ARE RATHER WEAK WITH INSTABILITY. DUE TO
MIXED SIGNALS CONFIDENCE IN THUNDER AND ENHANCED RAINFALL RATES
IS LOW. EXPECTED RAINFALL IS 0.5" TO 1" WITH ISOLD AMOUNTS UP TO
1.5" ACROSS W ZONES WHICH WOULD MAINLY RESULT IN MINOR URBAN AND
POOR DRAINAGE FLOODING ISSUES. RAINFALL WILL BE EXITING THE REGION
FROM WEST TO EAST 16-21Z.
HIGH WIND THREAT...
MODEL DIFFERENCES IN THE STRENGTH OF THE LOW LEVEL JET INCREASES
FORECAST UNCERTAINTY REGARDING MAGNITUDE OF THE WIND THREAT. GFS
IS STRONGEST WITH THE JET INDICATING 80 KT AT 925 MB...BUT NAM HAS
TRENDED WEAKER WITH 70 KT AND ECMWF IS WEAKEST AT 60 KT. DESPITE
THESE DIFFERENCES...IMPRESSIVE PRESSURE FALLS ARE FORECAST
COINCIDENT WITH THE LOW LEVEL JET WHICH WILL ENHANCE WIND
ACCELERATION AND TEMPS ARE EXPECTED TO SPIKE INTO THE 50S IN THE
COASTAL PLAIN WHICH WILL INCREASE MIXING POTENTIAL. MODEL
SOUNDINGS ARE NOT VERY SUPPORTIVE OF STRONG WINDS MIXING
DOWN...BUT THE MILDER TEMPS AND ISALLOBARIC CONTRIBUTION SUPPORT
STRONG WINDS REACHING THE SURFACE. AS MENTIONED ABOVE WE ARE NOT
CONFIDENT IN A FINE LINE OF CONVECTION WHICH WOULD FURTHER INCREASE
HIGH WIND THREAT BUT WE HAVE ENOUGH CONFIDENCE TO GO WITH A HIGH
WIND WARNING FOR CAPE/ISLANDS WHERE STRONGEST LOW LEVEL WINDS ARE
EXPECTED. ELSEWHERE WE WILL GO WITH A WIND ADVISORY FOR RI AND
EASTERN MA. TIMING OF STRONGEST WINDS WILL BE 14-17Z RI AND
16-19Z E MA AND CAPE/ISLANDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
MID LEVEL LOW MOVES INTO CENTRAL AND NORTHERN NEW ENG TONIGHT WITH
A STRONG SHORTWAVE ROTATING INTO THE REGION TOWARD MIDNIGHT. AS A
RESULT WE EXPECT SCT SNOW/RAIN SHOWERS TO REDEVELOP. BL TEMPS WILL
BE MARGINAL NEAR THE COAST WHERE ANY PRECIP MAY BE IN THE FORM OF
RAIN...BUT EXPECT MOSTLY SNOW SHOWERS ELSEWHERE. CANT RULE OUT
MINOR ACCUM IN THE HIGHER TERRAIN.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
HIGHLIGHTS...
* ARCTIC AIR MOVES IN BEHIND THE LOW PRES THROUGH THE WEEKEND
* WEAK LOW PRES MAY BRING LIGHT SNOW ON CHRISTMAS DAY
* STRONG STORM POSSIBLE WED NIGHT INTO THU
OVERVIEW AND MODEL PREFERENCES...
21/00Z MODEL GUIDANCE SUITE CONTINUES TO SHOW DECENT SYNOPTIC
SCALE AGREEMENT THROUGH THE EARLY PORTION OF THE LONG TERM BUT ARE
STRUGGLING WITH TWO DIFFERENT SYSTEMS AFFECTING THE MID AND LONG
TERM SENSIBLE WX DETAILS. ECMWF HAS COME IN LINE WITH GFS/NAM
TIMING FOR THE LOW PRES THIS WEEKEND EXITING INTO THE
MARITIMES...SO WILL CONTINUE TO BASELINE FORECAST USING GFS AS IT
HAS SHOWN MORE CONSISTENCY. THE DISAGREEMENTS BEGIN REGARDING
WITH THE E CANADA FLOW PATTERN FOR THE CHRISTMAS EVE/DAY SYSTEM. A
SPAGHETTI PLOT OF OPERATIONAL LONG RANGE GUIDANCE AND ENSEMBLES
AT H5 ARE ALL OVER THE PLACE WITH THE NRN NEW ENGLAND E CANADA
FLOW PATTERN...SO STILL NOT A LOT OF CONFIDENCE IN WHETHER OR NOT
HIGH PRES TO THE N WILL SUPPRESS LIGHT SNOW FOR CHRISTMAS EVE TO
THE S. THE LATEST ECMWF IS CLOSER TO THE SOLUTION SUGGESTED BY THE
GFS AND A FEW GEFS MEMBERS. WILL LEAN ON HPC AS FOR NOW GIVEN THE
DIFFERENCES AND ISSUES WITH UPPER LVL FLOW PATTERN. IN REGARDS TO
THE MID WEEK SYSTEM NEXT WEEK...GUIDANCE IS ACTUALLY IN DECENT
AGREEMENT WITH THE DEEPENING/SHARPENING WAVE MOVING E FROM THE
ROCKIES AGAIN...BUT GENERATE VERY DIFFERENT SFC CYCLONES. ECMWF
CONTINUES TO BE SIMILAR TO THE SYSTEM FOR TODAY AND THE WEEKEND
WHILE GFS PUSHES THE LOW NEAR THE 40/70 BENCHMARK. HPC LEANS
TOWARD THE ECENS THIS STRETCH...WHICH IS COOLER THAN THE
OPERATIONAL ECMWF...BUT WARMER THAN THE GFS...SO GIVEN THIS IS A
GOOD COMPROMISE...WILL CONTINUE TO USE IT FOR THE MID-LATE WEEK
SYSTEM.
DETAILS...
SAT INTO MON...
SLOW MOVING CUTOFF LOW PRES AND ITS WEAKENING SFC LOW WILL
GRADUALLY BE SHIFTING INTO THE MARITIMES THROUGH THE PERIOD. THIS
WILL ALLOW A MUCH COLDER AIRMASS TO MOVE IN WITH H92 TEMPS
AVERAGING THE -5C TO -8C RANGE. THEREFORE...WITH SOME REMNANT
ENERGY WRAPPING AROUND AND LOW LVL MOISTURE WRAPPING AROUND THE
LOW SAT...A FEW SNOW SHOWERS ARE LIKELY WHICH GIVEN COOLER SFC
TEMPS MAY ACCUMULATE IN SPOTS. GENERALLY AN INCH OR LESS
ACCUMULATION IS EXPECTED AT ANY GIVEN LOCATION. WITH DRY/COLD
AIRMASS SHIFTING INTO THE REGION...SUN AND MON ARE EXPECTED TO BE
MOSTLY DRY...BUT ON THE COLDER SIDE OF SEASONABLE FOR
TEMPERATURES.
MON NIGHT INTO TUE NIGHT...
GIVEN THE UNCERTAINTY HERE...THERE ARE STILL SOME QUESTIONS TO BE
ANSWERED REGARDING WEAK LOW PRES PASSING TO THE S OF SRN NEW
ENGLAND. SOUNDINGS AND DIVERGENCE FIELDS SHOW A WEAK TROWAL
WRAPPING TO THE N WITH TEMP PROFILES COOL ENOUGH FOR SNOW RIGHT TO
THE S COAST. GIVEN THE UNCERTAINTY HOWEVER...THERE COULD BE A
SHARP CUTOFF BETWEEN THOSE THAT SEE SOME OF THE WHITE FOR
CHRISTMAS AND THOSE THAT DON/T AND IT IS STILL POSSIBLE IT MAY BE
DRY ACROSS THE BOARD WITH STRONG HIGH PRES TO THE N. THE HPC STILL
FAVORS AREAS S OF THE MASS PIKE...SO WILL CONTINUE WITH THIS
SUGGESTION FOR THIS FORECAST UPDATE.
WED AND THU...
A MUCH MORE DYNAMIC SYSTEM WILL APPROACH FOR THE MID TO LATE WEEK
TIMEFRAME. GIVEN THE WIDE ENVELOPE OF SOLUTIONS FOR THIS WHICH
WILL HAVE SIGNIFICANT DIFFERENCES IN SENSIBLE WX DETAILS /GUIDANCE
RANGES FROM AN ALL RAIN TO AN ALL SNOW EVENT/. WILL TREND TOWARD
HPC WHICH IS AN ECENS BASES SOLUTION AT THIS TIME. THIS
COMPROMISES WITH SOME SNOW TO THE N AND RAIN IN THE S.
HOWEVER...NEITHER ALL SNOW OR ALL RAIN SOLUTIONS CAN/T BE RULED
OUT AND WILL HAVE TO BE MONITORED ESPECIALLY ONCE THE WAVE ITS
ASSOCIATED WITH CAN BE SAMPLED OVER LAND OBSERVING SITES.
FRI...
MODEL GUIDANCE DOES SUGGEST THAT IN ANY CASE...COOL HIGH PRES
WILL BE BUILDING IN TOWARD THE END OF THE WEEK...SO WILL LEAN
GUIDANCE IN THIS SOLUTION FOR THE EXTENDED PERIOD.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...HIGH CONFIDENCE.
THROUGH 12Z...MAINLY MVFR IN AREAS OF LIGHT RAIN. SNOW WITH IFR
CONDITIONS IN THE INTERIOR WILL CHANGE TO RAIN 08-11Z.
AFTER 12Z...HIGH PROBABILITY FOR IFR CONDITIONS AS BAND OF
RAIN...HEAVY AT TIMES MOVES THROUGH. STRONG ESE WINDS WITH A 2-3
HOUR PERIOD OF GUSTS 40-50 KT AND LLWS MOVING EAST ACROSS COASTAL
RI AND MA 14-19Z. IFR IMPROVING TO VFR FROM WEST TO EAST DURING
THE LATE AFTERNOON AND EVENING. SCT RAIN AND SNOW SHOWERS TONIGHT
WITH AREAS OF MVFR POSSIBLE.
KBOS TAF...HIGH CONFIDENCE IN IFR CONDITIONS DEVELOPING IN RAIN
AND STRONG SE WINDS WITH GUSTS TO 45 KT. MODERATE CONFIDENCE IN
TIMING. HEAVIEST RAIN AND STRONGEST WIND 16-19Z WITH IMPROVEMENT
TO VFR TOWARD 00Z.
KBDL TAF...HIGH CONFIDENCE IN IFR CONDITIONS DEVELOPING IN RAIN
AND SE GUSTS TO 25-30 KT. MODERATE CONFIDENCE IN TIMING. HEAVIEST
RAIN AND STRONGEST WIND 13-16Z WITH IMPROVEMENT TO VFR TOWARD
21Z.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY INTO SATURDAY NIGHT...MODERATE CONFIDENCE.
MAINLY VFR. HOWEVER...OCCASIONAL RAIN AND SNOW SHOWERS COULD
REDUCE BOTH VSBYS AND CIGS TO MVFR. WINDS GUST 30-40 KT OUT OF
THE NW SAT NIGHT.
SUNDAY AND MONDAY...HIGH CONFIDENCE.
VFR. NW WINDS GUST 20-30 KT THROUGH THE DAY ON SUN.
TUESDAY...MODERATE CONFIDENCE.
MAINLY VFR....BUT LIGHT SNOW IS POSSIBLE EARLY TUESDAY ESPECIALLY
TERMINALS S OF THE MASS PIKE.
&&
.MARINE...
MODERATE TO HIGH CONFIDENCE THROUGH TONIGHT.
A BRIEF PERIOD OF STORM FORCE SE WIND GUSTS TO NEAR 50 KT IS
EXPECTED FROM WEST TO EAST 14-20Z. STORM WARNINGS CONTINUE EXCEPT
STRONG GALES FOR NARR BAY AND BOSTON HARBOR. RAIN...HEAVY AT TIMES
IMPROVING FROM WEST TO EAST DURING THE AFTERNOON.
WINDS WILL DIMINISH WITH THE WIND SHIFT TO SW LATER THIS AFTERNOON
BUT STILL EXPECT WIND GUSTS TO 30 KT TONIGHT.
OUTLOOK...SATURDAY THROUGH TUESDAY...
MODERATE TO HIGH CONFIDENCE THROUGH TUESDAY.
SAT INTO SAT NIGHT...MODERATE CONFIDENCE.
WINDS BRIEFLY DIP TO SMALL CRAFT LEVELS DURING THE DAY
SATURDAY...BUT THEN ONCE WINDS SHIFT TO THE NW EXPECT GALE FORCE
GUSTS TO RETURN ESPECIALLY SAT NIGHT INTO EARLY SUNDAY. SEAS
REMAIN ELEVATED.
SUN INTO MON...HIGH CONFIDENCE.
BOTH WINDS AND SEAS GRADUALLY DIMINISH THROUGH THE PERIOD.
ALTHOUGH EXPECTING SMALL CRAFT WINDS THROUGH SUN NIGHT. BY
MON...SEAS AND WINDS SHOULD DROP BELOW SCA THRESHOLDS.
TUE...MODERATE CONFIDENCE.
WINDS AND SEAS START BELOW SMALL CRAFT THRESHOLDS...BUT MAY SEE
25 KT GUSTS AND SEAS NEAR 5 FT OVER SRN OUTER WATERS BY TUE
AFTERNOON AS A WEAK LOW PRES PASSES S OF THE REGION.
&&
.TIDES/COASTAL FLOODING...
NOT EXPECTING ANY COASTAL FLOODING OR BEACH EROSION AS ASTRO
TIDES ARE VERY LOW.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR MAZ005>007-
013>021.
HIGH WIND WARNING UNTIL 4 PM EST THIS AFTERNOON FOR MAZ022>024.
NH...NONE.
RI...HIGH WIND WARNING UNTIL 1 PM EST THIS AFTERNOON FOR RIZ008.
WIND ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR RIZ001>007.
MARINE...STORM WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ANZ231>234-250-
251-254-255.
GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ANZ230-236.
STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR ANZ235-237-256.
&&
$$
SYNOPSIS...KJC/DOODY
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...DOODY
AVIATION...KJC/DOODY
MARINE...KJC/DOODY
TIDES/COASTAL FLOODING...STAFF
AREA FORECAST DISCUSSION
NWS TAUNTON MA
408 AM EST FRI DEC 21 2012
.SYNOPSIS...
LOW PRESSURE AND ITS ATTENDING OCCLUDED FRONT WILL BRING A
PERIOD OF HEAVY RAIN AND STRONG WINDS TO THE REGION TODAY. COLDER
TEMPS WILL FOLLOW FOR THE WEEKEND INTO EARLY NEXT WEEK. A WEAK
STORM COULD BRING SOME SNOW AND/OR RAIN ON CHRISTMAS DAY. A
STRONGER STORM MAY AFFECT NEW ENGLAND LATE WED INTO THU.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SNOW IN THE DISTANT INTERIOR HAS ACCUMULATED 1-2 INCHES. IT IS
STILL SNOWING ACROSS WESTERN AND NORTHERN MA INTO S NH WITH TEMPS
32-34 DEGREES. HOWEVER...LOW LEVEL WARMING WILL RESULT IN A QUICK
CHANGEOVER TO RAIN THROUGH 6 AM. ADDITIONAL ACCUMULATION UP TO AN
INCH IS POSSIBLE.
A PERIOD OF STRONG WINDS AND HEAVY RAIN WILL MOVE ACROSS SNE
TODAY AS AN ANOMALOUS LOW LEVEL JET AHEAD OF A STRONG OCCLUDED
FRONT SWEEPS ACROSS THE REGION. THIS SYSTEM IS RATHER PROGRESSIVE
SO THE WORST OF THE WIND AND RAIN WILL LIKELY BE CONFINED TO A 3-4
HOUR WINDOW...12-16Z IN THE WEST AND 16-20Z EASTERN NEW ENG.
RAINFALL/FLOOD POTENTIAL...
STRONG LOW LEVEL JET 3-4SD AND +2SD PWAT ANOMALY WILL BRING A
PERIOD OF HEAVY RAIN TO SNE. HOWEVER...THIS SYSTEM WILL BE QUICK
MOVING LIMITING THE DURATION OF HEAVY RAIN IN ANY ONE LOCATION.
NAM IS THE MOST ROBUST WITH ELEVATED INSTABILITY PARAMETERS AND
SUGGEST POTENTIAL FOR SOME CONVECTION/THUNDER...AND HRRR IS
INDICATING A FINE LINE OF CONVECTION MOVING THROUGH.
HOWEVER...GFS AND ECMWF ARE RATHER WEAK WITH INSTABILITY. DUE TO
MIXED SIGNALS CONFIDENCE IN THUNDER AND ENHANCED RAINFALL RATES
IS LOW. EXPECTED RAINFALL IS 0.5" TO 1" WITH ISOLD AMOUNTS UP TO
1.5" ACROSS W ZONES WHICH WOULD MAINLY RESULT IN MINOR URBAN AND
POOR DRAINAGE FLOODING ISSUES. RAINFALL WILL BE EXITING THE REGION
FROM WEST TO EAST 16-21Z.
HIGH WIND THREAT...
MODEL DIFFERENCES IN THE STRENGTH OF THE LOW LEVEL JET INCREASES
FORECAST UNCERTAINTY REGARDING MAGNITUDE OF THE WIND THREAT. GFS
IS STRONGEST WITH THE JET INDICATING 80 KT AT 925 MB...BUT NAM HAS
TRENDED WEAKER WITH 70 KT AND ECMWF IS WEAKEST AT 60 KT. DESPITE
THESE DIFFERENCES...IMPRESSIVE PRESSURE FALLS ARE FORECAST
COINCIDENT WITH THE LOW LEVEL JET WHICH WILL ENHANCE WIND
ACCELERATION AND TEMPS ARE EXPECTED TO SPIKE INTO THE 50S IN THE
COASTAL PLAIN WHICH WILL INCREASE MIXING POTENTIAL. MODEL
SOUNDINGS ARE NOT VERY SUPPORTIVE OF STRONG WINDS MIXING
DOWN...BUT THE MILDER TEMPS AND ISALLOBARIC CONTRIBUTION SUPPORT
STRONG WINDS REACHING THE SURFACE. AS MENTIONED ABOVE WE ARE NOT
CONFIDENT IN A FINE LINE OF CONVECTION WHICH WOULD FURTHER INCREASE
HIGH WIND THREAT BUT WE HAVE ENOUGH CONFIDENCE TO GO WITH A HIGH
WIND WARNING FOR CAPE/ISLANDS WHERE STRONGEST LOW LEVEL WINDS ARE
EXPECTED. ELSEWHERE WE WILL GO WITH A WIND ADVISORY FOR RI AND
EASTERN MA. TIMING OF STRONGEST WINDS WILL BE 14-17Z RI AND
16-19Z E MA AND CAPE/ISLANDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
MID LEVEL LOW MOVES INTO CENTRAL AND NORTHERN NEW ENG TONIGHT WITH
A STRONG SHORTWAVE ROTATING INTO THE REGION TOWARD MIDNIGHT. AS A
RESULT WE EXPECT SCT SNOW/RAIN SHOWERS TO REDEVELOP. BL TEMPS WILL
BE MARGINAL NEAR THE COAST WHERE ANY PRECIP MAY BE IN THE FORM OF
RAIN...BUT EXPECT MOSTLY SNOW SHOWERS ELSEWHERE. CANT RULE OUT
MINOR ACCUM IN THE HIGHER TERRAIN.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
HIGHLIGHTS...
* ARCTIC AIR MOVES IN BEHIND THE LOW PRES THROUGH THE WEEKEND
* WEAK LOW PRES MAY BRING LIGHT SNOW ON CHRISTMAS DAY
* STRONG STORM POSSIBLE WED NIGHT INTO THU
MODELS ARE IN DECENT AGREEMENT THROUGH MUCH OF THE LONG TERM. THERE
ARE DISCREPANCIES WITH RESPECT TO THE TRACK OF A LOW PRESSURE SYSTEM
WEDNESDAY NIGHT AND THURSDAY. THE GFS DEVELOPS A LOW PRESSURE
SYSTEM IN NORTH CAROLINA OFF A PRIMARY LOW IN THE APPALACHIANS.
THIS SECONDARY LOW BECOMES THE PRIMARY AS IT MOVES UP THE EASTERN
SEABOARD MOVING OFFSHORE IN NEW JERSEY AND PASSING SOUTHERN NEW
ENGLAND JUST INSIDE THE 40/70 BENCHMARK. THE ECMWF BRINGS THE LOW
PRESSURE UP THE COAST AND THROUGH NEW YORK STATE. THE GFS KEEPS
COOLER TEMPERATURES IN THE AREA WITH POSSIBLY SOME WINTRY
PRECIPITATION WHILE THE ECMWF WOULD BE THE WARMER SOLUTION.
FRIDAY NIGHT THROUGH SATURDAY...UPPER LOW OVER NORTHERN NEW ENGLAND
WILL MOVE NORTHWARD INTO QUEBEC SATURDAY. THERE ARE DISCREPANCIES
WITH HOW QUICKLY THE UPPER TROUGH MOVES OUT OF THE NORTHEAST. THE
ECMWF IS THE SLOWEST AND KEEPS THE TROUGH OVER THE NORTHEAST THROUGH
SUNDAY. THE NAM IS SOMEWHAT MORE PROGRESSIVE AND THE GFS EVEN
FASTER...MOVING THE TROUGH INTO CANADA LATE SATURDAY. THE GFS/NAM
ARE HANDLING THE STORM SYSTEM BETTER CURRENTLY SO WILL USE A BLEND
FOR THIS TIME PERIOD. ALL MODELS INDICATE SOME LINGERING PRECIP
OVER SOUTHERN NEW ENGLAND FRIDAY NIGHT INTO SATURDAY MORNING.
EXPECT THAT AS COLD AIR STARTS TO WORK ITS WAY IN BEHIND THE FRONTAL
SYSTEM...RAIN WILL CHANGE TO SNOW FRIDAY NIGHT AND ANY LINGERING
SHOWERS/FLURRIES WILL BE AS SNOW SATURDAY. SNOW SHOULD COME TO AN
END SATURDAY AFTERNOON AND EVENING WITH DRIER AIR MOVING INTO THE
REGION. TEMPERATURES WILL DROP INTO THE UPPER TEENS TO MID 20S MOST
LOCATIONS OVERNIGHT.
SUNDAY AND MONDAY...DRY...COLD WEATHER EXPECTED AS HIGH PRESSURE
BUILDS IN OVER THE REGION. STRONG COLD AIR ADVECTION WILL BRING
COLDER AIR AND BREEZY CONDITIONS INTO SOUTHERN NEW ENGLAND SUNDAY.
HIGH TEMPERATURES SHOULD BE IN THE MID 20S TO MID 30S WHICH IS JUST
A FEW DEGREES COLDER THAN NORMAL FOR MID TO LATE DECEMBER.
CHRISTMAS DAY...LOW PRESSURE DEVELOPS OFF THE DELMARVA PENINSULA AND
MOVES OVER OR JUST SOUTH OF THE 40/70 BENCHMARK. THIS MAY BRING A
PERIOD OF LIGHT SNOW TO THE AREA. THERE IS SOME QUESTION HOW MUCH
OF AN INFLUENCE HIGH PRESSURE TO THE NORTH WILL HAVE ON PUSHING THAT
LOW FURTHER SOUTH WHICH WILL AFFECT THE NORTHWARD EXTENT OF ANY
PRECIPITATION THAT FALLS ON TUESDAY.
WEDNESDAY AND THURSDAY...THIS TIME FRAME IS THE PERIOD WITH THE MOST
MODEL DISCREPANCIES AND THAT ALL WITH THE PATH OF A LOW PRESSURE
SYSTEM MOVING OUT OF THE GULF OF MEXICO. THE ECMWF IS AN INSIDE
RUNNER BRINGING THE THE LOW UP THROUGH NEW YORK STATE AND IS THE
WARMER SOLUTION WITH MOSTLY RAIN...OR POSSIBLY SOME FREEZING
RAIN/ICE. THE GFS BRINGS THE LOW UP THE COAST AND OVER THE
BENCHMARK BRINGING COOLER TEMPERATURES AND LIKELY SNOW ACROSS MUCH
OF SOUTHERN NEW ENGLAND AND SOME RAIN ON THE CAPE AND ISLANDS.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...HIGH CONFIDENCE.
THROUGH 12Z...MAINLY MVFR IN AREAS OF LIGHT RAIN. SNOW WITH IFR
CONDITIONS IN THE INTERIOR WILL CHANGE TO RAIN 08-11Z.
AFTER 12Z...HIGH PROBABILITY FOR IFR CONDITIONS AS BAND OF
RAIN...HEAVY AT TIMES MOVES THROUGH. STRONG ESE WINDS WITH A 2-3
HOUR PERIOD OF GUSTS 40-50 KT AND LLWS MOVING EAST ACROSS COASTAL
RI AND MA 14-19Z. IFR IMPROVING TO VFR FROM WEST TO EAST DURING
THE LATE AFTERNOON AND EVENING. SCT RAIN AND SNOW SHOWERS TONIGHT
WITH AREAS OF MVFR POSSIBLE.
KBOS TAF...HIGH CONFIDENCE IN IFR CONDITIONS DEVELOPING IN RAIN
AND STRONG SE WINDS WITH GUSTS TO 45 KT. MODERATE CONFIDENCE IN
TIMING. HEAVIEST RAIN AND STRONGEST WIND 16-19Z WITH IMPROVEMENT
TO VFR TOWARD 00Z.
KBDL TAF...HIGH CONFIDENCE IN IFR CONDITIONS DEVELOPING IN RAIN
AND SE GUSTS TO 25-30 KT. MODERATE CONFIDENCE IN TIMING. HEAVIEST
RAIN AND STRONGEST WIND 13-16Z WITH IMPROVEMENT TO VFR TOWARD
21Z.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SAT...MODERATE CONFIDENCE. AREAS OF MVFR CIGS EXPECTED WITH SCT
RAIN/SNOW SHOWERS. GUSTY SW WINDS NEAR THE COAST FRI EVENING THEN
ANOTHER PULSE OF NW GUSTS TO 30 KT EXPECTED LATE SAT AND SAT
NIGHT.
SUNDAY AND MONDAY...HIGH CONFIDENCE. VFR. NW GUSTS TO 25 KT
SUN...DIMINISHING MON.
TUESDAY...MODERATE CONFIDENCE. MAINLY VFR. LIGHT SNOW POSSIBLE TUE
AFTN INTO TUE NIGHT.
&&
.MARINE...
MODERATE TO HIGH CONFIDENCE THROUGH TONIGHT.
A BRIEF PERIOD OF STORM FORCE SE WIND GUSTS TO NEAR 50 KT IS
EXPECTED FROM WEST TO EAST 14-20Z. STORM WARNINGS CONTINUE EXCEPT
STRONG GALES FOR NARR BAY AND BOSTON HARBOR. RAIN...HEAVY AT TIMES
IMPROVING FROM WEST TO EAST DURING THE AFTERNOON.
WINDS WILL DIMINISH WITH THE WIND SHIFT TO SW LATER THIS AFTERNOON
BUT STILL EXPECT WIND GUSTS TO 30 KT TONIGHT.
OUTLOOK...SATURDAY THROUGH TUESDAY...
MODERATE TO HIGH CONFIDENCE THROUGH TUESDAY.
SW SCA GUSTS TO 25-30 KT EXPECTED IN POST FRONTAL AIRMASS FRI NIGHT
INTO SAT...ESPECIALLY S COASTAL WATERS AS WINDS MAY TEMPORARILY
DIMINISH ACROSS NE MA WATERS LATE FRI NIGHT INTO SAT. ANOTHER PULSE
OF GALE FORCE WINDS EXPECTED SAT NIGHT WITH WIND SHIFT TO NW WHICH
MAY LINGER INTO SUN. WINDS WILL GRADUALLY DIMINISH SUN NIGHT INTO
MON BUT SCA GUSTS LIKELY. HAZARDOUS SEAS EXPECTED TO GRADUALLY
SUBSIDE SUN NIGHT AND MON. MON NIGHT AND TUE WINDS AND SEAS WILL
BE BELOW SCA CRITERIA.
&&
.TIDES/COASTAL FLOODING...
NOT EXPECTING ANY COASTAL FLOODING OR BEACH EROSION AS ASTRO
TIDES ARE VERY LOW.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...WIND ADVISORY FROM 7 AM THIS MORNING TO 3 PM EST THIS
AFTERNOON FOR MAZ005>007-013>021.
HIGH WIND WARNING FROM 7 AM THIS MORNING TO 4 PM EST THIS
AFTERNOON FOR MAZ022>024.
NH...NONE.
RI...HIGH WIND WARNING FROM 7 AM THIS MORNING TO 1 PM EST THIS
AFTERNOON FOR RIZ008.
WIND ADVISORY FROM 7 AM THIS MORNING TO 1 PM EST THIS
AFTERNOON FOR RIZ001>007.
MARINE...STORM WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ANZ231>234-250-
251-254-255.
GALE WARNING FROM 7 AM THIS MORNING TO 4 PM EST THIS AFTERNOON
FOR ANZ230-236.
STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR ANZ235-237-256.
&&
$$
SYNOPSIS...KJC/DOODY
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...DOODY
AVIATION...KJC/DOODY
MARINE...KJC/DOODY
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
251 AM EST FRI DEC 21 2012
.SYNOPSIS...
A POTENT AREA OF LOW PRESSURE WILL TRACK ACROSS THE GREAT LAKES AND
NORTHEAST TONIGHT AND FRIDAY, THEN ACROSS EASTERN CANADA DURING THE
WEEKEND. ITS ASSOCIATED STRONG COLD FRONT WILL SWEEP ACROSS OUR
REGION EARLY FRIDAY MORNING. A WEAK AREA OF HIGH PRESSURE THEN
BUILDS DOWN INTO OUR REGION LATE SUNDAY AND MONDAY. A WEAK LOW
PRESSURE SYSTEM MAY AFFECT OUR AREA MONDAY NIGHT INTO TUESDAY, WITH
THE POTENTIAL FOR A MUCH STRONGER STORM SET TO ARRIVE ON THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
STARTING IN THE POCONOS, WE ARE PLANNING ON LETTING THE ADVY
EXPIRE AT 11 PM. THE DRY AIR ALOFT HAS EVAP COOLED AND THE
FREEZING RAIN IN THE HIGHER TERRAIN HAS CHANGED TO SNOW. THE
NUMBER OF MESONET SITES BELOW FREEZING WHICH ONCE WAS AROUND 20 IS
DOWN TO 6. HRRR AND LATEST WRF-NMMB HAS EVERYONE ABOVE FREEZING BY
03Z. SOME SLIPPERY SPOTS WERE REPORTED IN THE HIGHER TERRAIN OF
MONROE COUNTY AND AROUND A QUARTER INCH OF SNOW IN PLACES.
NOW FOR THE OTHER WEATHER HAZARD, THE WIND. NOT AN EASY DECISION
BECAUSE THE SOUNDINGS ARE NEARLY ISOTHERMAL WITH POOR LAPSE RATES.
THE 00Z SOUNDINGS SUPPORTED A COMP BETWEEN THE WRF-NMMB AND GFS
FCST SPEEDS. SINCE THEN THE VWP LOOK OK AT KAKQ AND KLWX FOR THE
NEW WRF-NMMB 925MB WINDS, BUT THE MODEL IS RUNNING AROUND 5 TO
10 KTS TOO HOT AT 850MB. SO FAR THE MIXING OF STRONGER WINDS IN
THE CAROLINAS HAS BEEN SPORADIC. SO WHAT WE CAN GATHER THERE HAVE
NOT BEEN UPSIDE SURPRISES YET. THE OVERALL WIND FIELDS ARE
FORECAST THOUGH TO INTENSIFY FURTHER AS TIME GOES ON TONIGHT AND
THE MOMENTUM TRANSFER WINDS ON OCCASION ARE MIXING ADVY LEVEL WIND
GUSTS DOWN. THE MESOSCALE MODELS AND WE DONT KNOW IF THEY ARE THIS
GOOD ARE NOT FORECASTING A SINGLE NCFRB TOWARD MORNING. AFTER
COORD WITH OKX AND LOOKING AT THE 12/1/10 ANALOG THEY FOUND (WHICH
WAS AN ADVY TYPE EVENT CENTERED MAINLY IN THE ERN PART OF OUR
CWA), WE DECIDED TO ISSUE A WIND ADVY THAT COINCIDES CLOSEST WITH
THE 70KT OR GREATER ISOTACH ON THE LATEST WRF-NMMB. WE INCLUDED
ALL OF DELAWARE BAY BECAUSE OF THE SE FLOW. IF A NCFRB DOES FORM
NEAR THE JET MAX, THE ADVY MAY NEED TO BE UPGRADED OR EXPANDED.
RIGHT NOW CONFIDENCE IS TOO LOW TO ISSUE.
THE REST OF THE FCST WAS KEPT PRETTY MUCH AS IS, MOST OF THE
HEAVIEST PCPN IS EXPECTED TO FALL AFTER MIDNIGHT AND END RATHER
QUICKLY WITH THE CFP AROUND 12Z.
OTHER THAN SOME NUISANCE FLOODING, NO HYDRO ISSUES ARE EXPECTED.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
A THREAT OF RAIN SHOULD STILL EXIST FOR THE NORTHERN ZONES EARLY
TOMORROW MORNING. THEN WHEN THE UPPER LOW AND COLD POOL ALOFT MOVES
CLOSER, A SHOWER ANYWHERE CAN`T BE RULED OUT. TEMP PROFILES
SUGGEST SNOW SHOWERS FAR NORTH AND WEST.
TEMPS WILL HOLD STEADY OR FALL THROUGH THE 40S (30S NORTH AND WEST)
TOMORROW WITH WINDS GUSTING TO 30 OR 40 MPH.
LITTLE TO NO ACCUMULATION IS EXPECTED WHERE THE FLAKES FLY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
A RATHER ACTIVE PATTERN LOOKS TO CONTINUE. THE OVERALL SYNOPTIC FLOW
IS COMPRISED OF A DEEP TROUGH OVER THE EAST FRIDAY NIGHT AND
SATURDAY, THEN ADDITIONAL ENERGY PUSHING INTO THE WEST ALLOWS
DOWNSTREAM RIDGING TO KICK THE TROUGH INTO CANADA WHERE IT TENDS TO
BECOME ELONGATED WEST TO EAST. A PIECE OF ENERGY ROTATING AROUND
THIS MAY ALLOW FOR A SHORT WAVE TROUGH TO SLIDE ACROSS THE GREAT
LAKES INTO THE NORTHEAST AROUND TUESDAY. A MUCH MORE PRONOUNCED
UPPER-LEVEL TROUGH THEN LOOKS TO EJECT OUT OF THE FOUR CORNERS
REGION TUESDAY NIGHT INTO WEDNESDAY. THIS FEATURE ALONG WITH A
DEEPENING SURFACE LOW IS THEN FORECAST TO MOVE THROUGH THE EAST NEXT
THURSDAY. OVERALL, THE MODEL GUIDANCE CONTINUES TO SHOW VARIABILITY
WITH TIMING AND SPACING OF EMBEDDED INDIVIDUAL FEATURES HOWEVER
CONTINUED SUPPORT FOR AN ACTIVE PATTERN. THE THERMAL GRADIENTS AND
AMPLITUDE OF THE PATTERN MAY BE PLAYING A ROLE WITH THE MODEL
VARIABILITY. IT APPEARS THERE IS AN INCREASING SIGNAL FOR AN EAST
COAST STORM DURING ABOUT THE SECOND HALF OF NEXT WEEK. OF COURSE
THIS FAR OUT, THE DETAILS ARE MUCH LESS CERTAIN AND THEREFORE MUCH
LOWER CONFIDENCE IN THE FORECAST BEYOND TUESDAY ESPECIALLY.
FOR FRIDAY NIGHT AND SATURDAY...AN INTENSE STORM IS FORECAST TO BE
IN THE SOUTHEAST CANADA AND NEW ENGLAND AREAS DURING THIS TIME
FRAME. IT WILL BE DRIVEN BY A SHARP UPPER-LEVEL TROUGH WITH A SHOT
OF MUCH COLDER AIR ALONG WITH IT. A RATHER DEEP CYCLONIC FLOW REGIME
WILL BE OCCURRING WITH THE POTENTIAL FOR SOME WRAPAROUND SNOW
SHOWERS, AND THE LAKE EFFECT SNOW MACHINE SHOULD BE IN HIGH GEAR. AS
THE CAA CONTINUES, SHORT WAVE ENERGY ROTATING AROUND THE PARENT
UPPER-LEVEL TROUGH SHOULD HELP TO MAINTAIN SOME SNOW SHOWERS INTO
OUR NORTHWEST ZONES. SOME OF THE MODEL GUIDANCE SHOWING SIGNS OF
CHANNELIZED VORTICITY ORIENTATED NORTHWEST TO SOUTHEAST. IF DEEP
ENOUGH MOISTURE CAN BE MAINTAINED AND ENOUGH LIFT/INSTABILITY CAN
OCCUR WITHIN THE NORTHWEST FLOW, SOME LOCALIZED SNOW SQUALLS MAY
OCCUR ACROSS NORTHEASTERN PENNSYLVANIA AND NORTHWESTERN NEW JERSEY.
WE WOULD LIKE TO SEE BETTER ORGANIZATION OF THE CHANNELIZED
VORTICITY TO INCREASE CONFIDENCE REGARDING LAKE EFFECT STREAMERS
REMAINING INTACT THIS FAR SOUTHEAST FROM THE LAKES. FOR NOW, WE
CARRIED LOW LIKELY POPS ACROSS THE POCONOS AND TOWARD FAR NORTHWEST
NEW JERSEY, THEN POPS TAPER WITH A SOUTHEASTWARD EXTENT. BEYOND THE
SLIGHT CHC POPS, WE CARRIED SCATTERED FLURRIES DOWN TO THE
INTERSTATE 95 CORRIDOR. SOME PLACES PARTICULARLY IN THE POCONOS
COULD PICK UP AN INCH OR TWO OF SNOW. FARTHER SOUTHEAST, WHILE A FEW
HEAVIER SNOW SHOWERS MAY BE ABLE TO OCCUR, THE DOWNSLOPING FLOW MAY
PROVIDE ENOUGH EXTRA DRYING TO ERODE THESE. THIS IS OF LOWER
CONFIDENCE THEREFORE DID NOT BRING THE SNOW SHOWER MENTION EVEN
FARTHER SOUTHEAST AND WENT WITH FLURRIES.
ANOTHER FORECAST CONCERN IS THE STRONG WIND POTENTIAL. A RATHER
TIGHT PRESSURE GRADIENT IS FORECAST TO REMAIN ACROSS OUR ENTIRE. THE
CAA COMBINED WITH THE TIGHT PRESSURE GRADIENT SHOULD KEEP THE SURFACE
WINDS GOING FRIDAY NIGHT DESPITE LESSENING VERTICAL MIXING AT TIMES.
THE VERTICAL MIXING IS MUCH MORE PRONOUNCED SATURDAY AS THE AIRMASS
IS CHILLY, THE LOW-LEVEL LAPSE RATES STEEPEN SOME MORE AND THERE IS
PLENTY OF WIND NOT TO FAR ABOVE THE SURFACE. THE FORECAST SOUNDINGS
GET CLOSE TO 40 KNOTS POTENTIALLY MIXING DOWN TO THE SURFACE,
ALTHOUGH THE GFS IS MORE ROBUST WITH THIS AS IT SUGGESTS NEARLY
50 KNOTS MIXING DOWN TO THE SURFACE. THE 925 MB WINDS ARE NOT AS
STRONG ON THE ECMWF WITH AROUND 40 KNOTS FORECAST SATURDAY
ESPECIALLY ACROSS THE SOUTHERN HALF OF OUR CWA. WE THOUGHT ABOUT
GOING WITH A HIGH WIND WATCH WITH THE GREATER CHC ACROSS ABOUT THE
SOUTHERN HALF OF THE CWA, HOWEVER THIS IS NEARLY TWO DAYS OUT. IT
MAY END UP BEING A WIND ADVISORY TYPE EVENT THEREFORE WE DECIDED TO
HOLD OFF ON ANY HEADLINES ATTM. WE HOWEVER WILL CONTINUE A
MENTION IN THE HAZARDOUS WEATHER OUTLOOK. WE INCREASED THE WINDS
SOME /ESPECIALLY GUSTS/ FOR SATURDAY FROM CONTINUITY WITH GUSTS
GENERALLY IN THE 40-45 MPH RANGE. AS FOR HIGH AND LOW TEMPERATURES,
WE GENERALLY TOOK AN EVEN BLEND OF THE NAM/GFS MOS.
FOR SUNDAY AND MONDAY /CHRISTMAS EVE/...THE POTENT STORM IS FORECAST
TO MOVE UP THROUGH THE CANADIAN MARITIMES, HOWEVER A TIGHTENED
PRESSURE GRADIENT GENERALLY REMAINS IN PLACE. THE OVERALL FLOW
THOUGH WILL BE LESSENING, HOWEVER VERTICAL MIXING WILL PROVIDE
ENOUGH FOR A BRISK DAY ON SUNDAY. IT APPEARS THAT WITHIN THE
NORTHWESTERLY FLOW, A SHORT WAVE ROTATING AROUND THE PARENT STORM
MAY TOSS A SURFACE TROUGH OR COLD FRONT TOWARD OUR REGION. THE LAKE
EFFECT SNOW MACHINE SHOULD BE WINDING DOWN SUNDAY AS THE CAA WANES
SOME AND THE LOW-LEVEL FLOW MAY TURN MORE WESTERLY.
A SHORT WAVE TRAVERSING THE NORTHERN TIER CHRISTMAS EVE MAY ALLOW
FOR A SURFACE LOW REFLECTION TO RACE OUT AHEAD OF THE DEEPENING
TROUGH IN THE WEST. SOME MOISTURE RETURN AHEAD OF IT ALONG WITH WAA,
MAY RESULT IN AN AREA OF OVERRUNNING PRECIPITATION. THERE IS A
QUESTION REGARDING HOW DRY THE AIRMASS IS OVER OUR AREA AND THE
STRENGTH OF THE OVERALL LIFT. A LIGHT INTENSITY OF THE PRECIPITATION
MAY PLAY MORE OF A ROLE, WITH EVEN DEPENDING ON HOW THE BOUNDARY
LAYER BEHAVES. FOR NOW WE WILL FAVOR SLIGHT CHC POPS FOR A WEAK
OVERRUNNING POTENTIAL AND GO RAIN AND/OR SNOW.
FOR TUESDAY...THE AFOREMENTIONED FRONT RUNNER WEAKER SURFACE WAVE
SHOULD SCOOT OUT TO SEA EARLY TUESDAY AS THE SHORT WAVE TROUGH MAY
END UP DAMPENING OUT SOME. WHILE THERE COULD BE SOME RESIDUAL LIGHT
PRECIPITATION AROUND TO START TUESDAY, WE SIMPLY FAVORED SLIGHT CHC
POPS IN THE MORNING GIVEN LOWER CONFIDENCE ON TIMING AND OF ANY MORE
ORGANIZED LIFT.
FOR WEDNESDAY AND THURSDAY...THE PATTERN ONCE AGAIN STARTS TO REALLY
RAMP UP WEDNESDAY AS ENERGY FROM THE FOUR CORNERS REGION SLIDES
ACROSS THE PLAINS AND THEN THE TENNESSEE VALLEY. THERE IS ANOTHER
SYSTEM UP IN THE CANADIAN MARITIMES OVERALL, WHICH WOULD TEND TO
LEAD TO BLOCKING. THIS DEVELOPING PATTERN IS LOOKING MORE CONDUCIVE
FOR A COASTAL STORM TO OCCUR. IN THIS UPCOMING POTENTIAL, THE
INITIAL SURFACE LOW MAY TRACK UP THE OHIO VALLEY BUT THEN WEAKEN.
HIGH PRESSURE POSITIONED OVER EASTERN CANADA, IF IT CAN BE
MAINTAINED, MAY HELP TO WEDGE A COLDER LOW-LEVEL AIRMASS SOUTHWARD
ACROSS AT LEAST PORTIONS OF OUR AREA. THIS COLD AIR DAMMING SCENARIO
WOULD OPEN THE DOOR FOR SURFACE LOW REDEVELOPMENT NEAR THE VIRGINIA
COAST AS THE BAROCLINICITY TIGHTENS UP DUE TO THE THERMAL GRADIENT
INCREASING. THIS WOULD PROBABLY ALLOW FOR SOME WARMING ESPECIALLY
ALOFT UNTIL THE MAIN STORM GETS GOING OFF OR ALONG THE COAST.
THEREFORE, CLOUDS INCREASE WEDNESDAY AND WE WENT WITH 40-50 POPS FOR
NOW AS THE POTENTIAL IS THERE FORE A DECENT STORM. WE HELD OFF ON
GOING WITH LIKELY POPS DUE TO ENOUGH MODEL UNCERTAINTY REGARDING
TIMING AND ESPECIALLY THE DETAILS. WE WENT WITH RAIN AND/OR SNOW FOR
THE PRECIPITATION TYPE AS ANY OTHER FROZEN/FREEZING PRECIPITATION IS
MORE DEPENDENT ON THE ACTUAL THERMAL STRUCTURES.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THE 00Z TAFS CONTINUED THE DECENT INTO IFR AND LIFR AS THE
HEAVIER RAIN MOVES IN TONIGHT WITH THE LOWEST CONDITIONS AFTER
MIDNIGHT. WE ALSO CONTINUED THE MENTION OF LLWS. THE GRADIENT EAST
TO SOUTHEAST WIND ITSELF WILL ALSO INCREASE AND GUSTS TO AROUND 40
KTS ARE POSSIBLE AT TERMINALS AND AIRPORTS CLOSER TO THE OCEAN IN
NEW JERSEY AND DELAWARE.
THE COLD FRONT IS EXPECTED TO MOVE THROUGH FROM SOUTHWEST TO
NORTHEAST ACROSS OUR CWA WITH PASSAGE TIME PLUS OR MINUS OF 12Z
BY A COUPLE OF HOURS. RAPID IMPROVEMENT TO MVFR IF NOT VFR
CONDITIONS IS THEN FORECAST. WINDS THOUGH WILL REMAIN BLUSTERY,
BUT THIS TIME FROM THE WEST. CIGS SHOULD IMPROVE TO VFR BY LATE IN
THE MORNING. WINDS WILL REMAIN BRISK THROUGH THE DAY. PEAK GUSTS
OF AROUND 30 KTS ARE LIKELY.
OUTLOOK...
FRIDAY NIGHT AND SATURDAY...MAINLY VFR. WEST-NORTHWEST WINDS
SUSTAINED 15-25 KNOTS WITH GUSTS TO AROUND 35 KNOTS. THE STRONGER
WINDS SHOULD OCCUR DURING THE DAY SATURDAY. THERE COULD BE SOME
SUB-VFR CONDITIONS IN LOCAL/BRIEF SNOW SHOWERS ESPECIALLY FROM THE
KABE AND KRDG TERMINALS NORTH AND WEST.
SUNDAY...VFR WITH NORTHWESTERLY WINDS MAINLY 10-20 KNOTS.
MONDAY AND TUESDAY...VFR MONDAY ALTHOUGH CLOUDS SHOULD INCREASE AND
LOWER SOME. A WEAKER SYSTEM MAY MOVE THROUGH MONDAY NIGHT INTO
TUESDAY WITH THE CHANCE OF SOME LIGHT PRECIPITATION. LIGHT WINDS
MONDAY BECOME NORTHERLY NEAR 10 KNOTS TUESDAY.
&&
.MARINE...
A STRONG COLD FRONT WILL TRACK ACROSS OUR REGION EARLY TOMORROW
MORNING. GALES REMAIN IN PLACE FROM 700 PM TONIGHT, THROUGH THE
SHORT TERM PERIOD, AND INTO THE OUTLOOK PERIOD. SOUTHEAST WINDS
TONIGHT WILL BECOME SOUTHWEST TOMORROW. SEAS WILL RESPOND AND COULD
REACH DOUBLE DIGITS. RAIN OVERNIGHT TONIGHT WILL BECOME MOE SHOWERY
TOMORROW.
OUTLOOK...
A POTENT STORM IS FORECAST TO BE TO OUR NORTH FRIDAY NIGHT THROUGH
SATURDAY BEFORE SHIFTING INTO THE CANADIAN MARITIMES DURING THE
WEEKEND. A TIGHT PRESSURE GRADIENT IN COMBINATION WITH CAA WILL
ALLOW FOR STEEPER LOW-LEVEL LAPSE RATES AND EFFICIENT VERTICAL
MIXING. THE GFS 925 MB WINDS ARE MUCH STRONGER COMPARED TO THE NAM
AND ECMWF, HOWEVER ALL POINT TO GALE FORCE WINDS OCCURRING. THE GFS
WOULD SUGGEST A CHC FOR A PERIOD OF STORM FORCE GUSTS. WE ARE NOT
ALL THAT CONFIDENT REGARDING STORMS, THEREFORE WE WILL CONTINUE WITH
THE GALE WARNING THROUGH THE DAY SATURDAY. THE WINDS SHOULD START
DIMINISHING SATURDAY NIGHT, THEREFORE WE DECIDED NOT TO EXTEND THE
GALE WARNING ATTM. THERE SHOULD BE A PERIOD OF SMALL CRAFT ADVISORY
CONDITIONS FOLLOWING THE GALES INTO ABOUT SUNDAY. A WEAK SYSTEM MAY
THEN MOVE THROUGH MONDAY NIGHT INTO TUESDAY, HOWEVER THE WINDS AND
SEAS ARE ANTICIPATED TO BE BELOW ADVISORY CRITERIA.
&&
.TIDES/COASTAL FLOODING...
THE STRENGTHENING SOUTHEAST FLOW WILL ALLOW WATER TO PILE UP ALONG
THE COASTAL SECTIONS OF THE OCEAN...DELAWARE BAY AND CHESAPEAKE
BAY TONIGHT AND FRIDAY MORNING.
LOWER DELAWARE BAY AND THE SHORE...MINOR TIDAL FLOODING LEVELS
OCCURRING PRESENTLY.
UPPER DELAWARE BAY...MODERATE TIDAL FLOODING EXPECTED. DEPARTURES
ROSE SHARPLY EARLIER...BUT ARE LEVELING OFF NOW. THE HIGH TIDE AT
REEDY POINT IS AT 532 AM.
TIDAL DELAWARE...HIGH DEPARTURES EXPECTED TO CREATE MODERATE
FLOODING THIS MORNING. HIGH TIDE AT PHILADELPHIA 815 AM.
CHESAPEAKE BAY...DEPARTURES ARE CONTINUING TO INCREASE WITH THE
PRESENT CYCLE. MINOR TIDAL FLOODING WILL OCCUR OVER THE NORTHERN
PART OF THE BAY WITH THE PRESENT CYCLE...UNTIL AROUND 700 AM. THE
DEPARTURES WILL LIKELY FALL THIS AFTERNOON ONCE THE WINDS SWITCH
AROUND TO WEST OR SOUTHWEST. I HAVE EXTENDED THE CF.A THROUGH THE
NEXT CYCLE JUST IN CASE THE DEPARTURES DONT FALL ENOUGH IN TIME.
THE FLAG MATCHES UP WITH THE FLAGS ON THE OTHER SIDE OF THE BAY
ALSO.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...COASTAL FLOOD WARNING UNTIL 11 AM EST THIS MORNING FOR PAZ070-
071.
NJ...WIND ADVISORY UNTIL 9 AM EST THIS MORNING FOR NJZ001-008-010-
012>014-016-020>027.
COASTAL FLOOD ADVISORY UNTIL 8 AM EST THIS MORNING FOR
NJZ012>014-020-022>027.
COASTAL FLOOD WARNING UNTIL 8 AM EST THIS MORNING FOR NJZ016-
021.
COASTAL FLOOD WARNING UNTIL 11 AM EST THIS MORNING FOR
NJZ017>019.
DE...WIND ADVISORY UNTIL 9 AM EST THIS MORNING FOR DEZ001>004.
COASTAL FLOOD ADVISORY UNTIL 8 AM EST THIS MORNING FOR DEZ003-
004.
COASTAL FLOOD WARNING UNTIL 8 AM EST THIS MORNING FOR DEZ001-
002.
MD...WIND ADVISORY UNTIL 9 AM EST THIS MORNING FOR MDZ015-019-020.
COASTAL FLOOD ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
MDZ008-012-015-019-020.
MARINE...GALE WARNING UNTIL 7 PM EST SATURDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI/KRUZDLO
SHORT TERM...KRUZDLO
LONG TERM...GORSE
AVIATION...GIGI/GORSE
MARINE...GORSE/KRUZDLO
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1251 AM EST FRI DEC 21 2012
.SYNOPSIS...
A POTENT AREA OF LOW PRESSURE WILL TRACK ACROSS THE GREAT LAKES AND
NORTHEAST TONIGHT AND FRIDAY, THEN ACROSS EASTERN CANADA DURING THE
WEEKEND. ITS ASSOCIATED STRONG COLD FRONT WILL SWEEP ACROSS OUR
REGION EARLY FRIDAY MORNING. A WEAK AREA OF HIGH PRESSURE THEN
BUILDS DOWN INTO OUR REGION LATE SUNDAY AND MONDAY. A WEAK LOW
PRESSURE SYSTEM MAY AFFECT OUR AREA MONDAY NIGHT INTO TUESDAY, WITH
THE POTENTIAL FOR A MUCH STRONGER STORM SET TO ARRIVE ON THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
STARTING IN THE POCONOS, WE ARE PLANNING ON LETTING THE ADVY
EXPIRE AT 11 PM. THE DRY AIR ALOFT HAS EVAP COOLED AND THE
FREEZING RAIN IN THE HIGHER TERRAIN HAS CHANGED TO SNOW. THE
NUMBER OF MESONET SITES BELOW FREEZING WHICH ONCE WAS AROUND 20 IS
DOWN TO 6. HRRR AND LATEST WRF-NMMB HAS EVERYONE ABOVE FREEZING BY
03Z. SOME SLIPPERY SPOTS WERE REPORTED IN THE HIGHER TERRAIN OF
MONROE COUNTY AND AROUND A QUARTER INCH OF SNOW IN PLACES.
NOW FOR THE OTHER WEATHER HAZARD, THE WIND. NOT AN EASY DECISION
BECAUSE THE SOUNDINGS ARE NEARLY ISOTHERMAL WITH POOR LAPSE RATES.
THE 00Z SOUNDINGS SUPPORTED A COMP BETWEEN THE WRF-NMMB AND GFS
FCST SPEEDS. SINCE THEN THE VWP LOOK OK AT KAKQ AND KLWX FOR THE
NEW WRF-NMMB 925MB WINDS, BUT THE MODEL IS RUNNING AROUND 5 TO
10 KTS TOO HOT AT 850MB. SO FAR THE MIXING OF STRONGER WINDS IN
THE CAROLINAS HAS BEEN SPORADIC. SO WHAT WE CAN GATHER THERE HAVE
NOT BEEN UPSIDE SURPRISES YET. THE OVERALL WIND FIELDS ARE
FORECAST THOUGH TO INTENSIFY FURTHER AS TIME GOES ON TONIGHT AND
THE MOMENTUM TRANSFER WINDS ON OCCASION ARE MIXING ADVY LEVEL WIND
GUSTS DOWN. THE MESOSCALE MODELS AND WE DONT KNOW IF THEY ARE THIS
GOOD ARE NOT FORECASTING A SINGLE NCFRB TOWARD MORNING. AFTER
COORD WITH OKX AND LOOKING AT THE 12/1/10 ANALOG THEY FOUND (WHICH
WAS AN ADVY TYPE EVENT CENTERED MAINLY IN THE ERN PART OF OUR
CWA), WE DECIDED TO ISSUE A WIND ADVY THAT COINCIDES CLOSEST WITH
THE 70KT OR GREATER ISOTACH ON THE LATEST WRF-NMMB. WE INCLUDED
ALL OF DELAWARE BAY BECAUSE OF THE SE FLOW. IF A NCFRB DOES FORM
NEAR THE JET MAX, THE ADVY MAY NEED TO BE UPGRADED OR EXPANDED.
RIGHT NOW CONFIDENCE IS TOO LOW TO ISSUE.
THE REST OF THE FCST WAS KEPT PRETTY MUCH AS IS, MOST OF THE
HEAVIEST PCPN IS EXPECTED TO FALL AFTER MIDNIGHT AND END RATHER
QUICKLY WITH THE CFP AROUND 12Z.
OTHER THAN SOME NUISANCE FLOODING, NO HYDRO ISSUES ARE EXPECTED.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
A THREAT OF RAIN SHOULD STILL EXIST FOR THE NORTHERN ZONES EARLY
TOMORROW MORNING. THEN WHEN THE UPPER LOW AND COLD POOL ALOFT MOVES
CLOSER, A SHOWER ANYWHERE CAN`T BE RULED OUT. TEMP PROFILES
SUGGEST SNOW SHOWERS FAR NORTH AND WEST.
TEMPS WILL HOLD STEADY OR FALL THROUGH THE 40S (30S NORTH AND WEST)
TOMORROW WITH WINDS GUSTING TO 30 OR 40 MPH.
LITTLE TO NO ACCUMULATION IS EXPECTED WHERE THE FLAKES FLY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
A RATHER ACTIVE PATTERN LOOKS TO CONTINUE. THE OVERALL SYNOPTIC FLOW
IS COMPRISED OF A DEEP TROUGH OVER THE EAST FRIDAY NIGHT AND
SATURDAY, THEN ADDITIONAL ENERGY PUSHING INTO THE WEST ALLOWS
DOWNSTREAM RIDGING TO KICK THE TROUGH INTO CANADA WHERE IT TENDS TO
BECOME ELONGATED WEST TO EAST. A PIECE OF ENERGY ROTATING AROUND
THIS MAY ALLOW FOR A SHORT WAVE TROUGH TO SLIDE ACROSS THE GREAT
LAKES INTO THE NORTHEAST AROUND TUESDAY. A MUCH MORE PRONOUNCED
UPPER-LEVEL TROUGH THEN LOOKS TO EJECT OUT OF THE FOUR CORNERS
REGION TUESDAY NIGHT INTO WEDNESDAY. THIS FEATURE ALONG WITH A
DEEPENING SURFACE LOW IS THEN FORECAST TO MOVE THROUGH THE EAST NEXT
THURSDAY. OVERALL, THE MODEL GUIDANCE CONTINUES TO SHOW VARIABILITY
WITH TIMING AND SPACING OF EMBEDDED INDIVIDUAL FEATURES HOWEVER
CONTINUED SUPPORT FOR AN ACTIVE PATTERN. THE THERMAL GRADIENTS AND
AMPLITUDE OF THE PATTERN MAY BE PLAYING A ROLE WITH THE MODEL
VARIABILITY. IT APPEARS THERE IS AN INCREASING SIGNAL FOR AN EAST
COAST STORM DURING ABOUT THE SECOND HALF OF NEXT WEEK. OF COURSE
THIS FAR OUT, THE DETAILS ARE MUCH LESS CERTAIN AND THEREFORE MUCH
LOWER CONFIDENCE IN THE FORECAST BEYOND TUESDAY ESPECIALLY.
FOR FRIDAY NIGHT AND SATURDAY...AN INTENSE STORM IS FORECAST TO BE
IN THE SOUTHEAST CANADA AND NEW ENGLAND AREAS DURING THIS TIME
FRAME. IT WILL BE DRIVEN BY A SHARP UPPER-LEVEL TROUGH WITH A SHOT
OF MUCH COLDER AIR ALONG WITH IT. A RATHER DEEP CYCLONIC FLOW REGIME
WILL BE OCCURRING WITH THE POTENTIAL FOR SOME WRAPAROUND SNOW
SHOWERS, AND THE LAKE EFFECT SNOW MACHINE SHOULD BE IN HIGH GEAR. AS
THE CAA CONTINUES, SHORT WAVE ENERGY ROTATING AROUND THE PARENT
UPPER-LEVEL TROUGH SHOULD HELP TO MAINTAIN SOME SNOW SHOWERS INTO
OUR NORTHWEST ZONES. SOME OF THE MODEL GUIDANCE SHOWING SIGNS OF
CHANNELIZED VORTICITY ORIENTATED NORTHWEST TO SOUTHEAST. IF DEEP
ENOUGH MOISTURE CAN BE MAINTAINED AND ENOUGH LIFT/INSTABILITY CAN
OCCUR WITHIN THE NORTHWEST FLOW, SOME LOCALIZED SNOW SQUALLS MAY
OCCUR ACROSS NORTHEASTERN PENNSYLVANIA AND NORTHWESTERN NEW JERSEY.
WE WOULD LIKE TO SEE BETTER ORGANIZATION OF THE CHANNELIZED
VORTICITY TO INCREASE CONFIDENCE REGARDING LAKE EFFECT STREAMERS
REMAINING INTACT THIS FAR SOUTHEAST FROM THE LAKES. FOR NOW, WE
CARRIED LOW LIKELY POPS ACROSS THE POCONOS AND TOWARD FAR NORTHWEST
NEW JERSEY, THEN POPS TAPER WITH A SOUTHEASTWARD EXTENT. BEYOND THE
SLIGHT CHC POPS, WE CARRIED SCATTERED FLURRIES DOWN TO THE
INTERSTATE 95 CORRIDOR. SOME PLACES PARTICULARLY IN THE POCONOS
COULD PICK UP AN INCH OR TWO OF SNOW. FARTHER SOUTHEAST, WHILE A FEW
HEAVIER SNOW SHOWERS MAY BE ABLE TO OCCUR, THE DOWNSLOPING FLOW MAY
PROVIDE ENOUGH EXTRA DRYING TO ERODE THESE. THIS IS OF LOWER
CONFIDENCE THEREFORE DID NOT BRING THE SNOW SHOWER MENTION EVEN
FARTHER SOUTHEAST AND WENT WITH FLURRIES.
ANOTHER FORECAST CONCERN IS THE STRONG WIND POTENTIAL. A RATHER
TIGHT PRESSURE GRADIENT IS FORECAST TO REMAIN ACROSS OUR ENTIRE. THE
CAA COMBINED WITH THE TIGHT PRESSURE GRADIENT SHOULD KEEP THE SURFACE
WINDS GOING FRIDAY NIGHT DESPITE LESSENING VERTICAL MIXING AT TIMES.
THE VERTICAL MIXING IS MUCH MORE PRONOUNCED SATURDAY AS THE AIRMASS
IS CHILLY, THE LOW-LEVEL LAPSE RATES STEEPEN SOME MORE AND THERE IS
PLENTY OF WIND NOT TO FAR ABOVE THE SURFACE. THE FORECAST SOUNDINGS
GET CLOSE TO 40 KNOTS POTENTIALLY MIXING DOWN TO THE SURFACE,
ALTHOUGH THE GFS IS MORE ROBUST WITH THIS AS IT SUGGESTS NEARLY
50 KNOTS MIXING DOWN TO THE SURFACE. THE 925 MB WINDS ARE NOT AS
STRONG ON THE ECMWF WITH AROUND 40 KNOTS FORECAST SATURDAY
ESPECIALLY ACROSS THE SOUTHERN HALF OF OUR CWA. WE THOUGHT ABOUT
GOING WITH A HIGH WIND WATCH WITH THE GREATER CHC ACROSS ABOUT THE
SOUTHERN HALF OF THE CWA, HOWEVER THIS IS NEARLY TWO DAYS OUT. IT
MAY END UP BEING A WIND ADVISORY TYPE EVENT THEREFORE WE DECIDED TO
HOLD OFF ON ANY HEADLINES ATTM. WE HOWEVER WILL CONTINUE A
MENTION IN THE HAZARDOUS WEATHER OUTLOOK. WE INCREASED THE WINDS
SOME /ESPECIALLY GUSTS/ FOR SATURDAY FROM CONTINUITY WITH GUSTS
GENERALLY IN THE 40-45 MPH RANGE. AS FOR HIGH AND LOW TEMPERATURES,
WE GENERALLY TOOK AN EVEN BLEND OF THE NAM/GFS MOS.
FOR SUNDAY AND MONDAY /CHRISTMAS EVE/...THE POTENT STORM IS FORECAST
TO MOVE UP THROUGH THE CANADIAN MARITIMES, HOWEVER A TIGHTENED
PRESSURE GRADIENT GENERALLY REMAINS IN PLACE. THE OVERALL FLOW
THOUGH WILL BE LESSENING, HOWEVER VERTICAL MIXING WILL PROVIDE
ENOUGH FOR A BRISK DAY ON SUNDAY. IT APPEARS THAT WITHIN THE
NORTHWESTERLY FLOW, A SHORT WAVE ROTATING AROUND THE PARENT STORM
MAY TOSS A SURFACE TROUGH OR COLD FRONT TOWARD OUR REGION. THE LAKE
EFFECT SNOW MACHINE SHOULD BE WINDING DOWN SUNDAY AS THE CAA WANES
SOME AND THE LOW-LEVEL FLOW MAY TURN MORE WESTERLY.
A SHORT WAVE TRAVERSING THE NORTHERN TIER CHRISTMAS EVE MAY ALLOW
FOR A SURFACE LOW REFLECTION TO RACE OUT AHEAD OF THE DEEPENING
TROUGH IN THE WEST. SOME MOISTURE RETURN AHEAD OF IT ALONG WITH WAA,
MAY RESULT IN AN AREA OF OVERRUNNING PRECIPITATION. THERE IS A
QUESTION REGARDING HOW DRY THE AIRMASS IS OVER OUR AREA AND THE
STRENGTH OF THE OVERALL LIFT. A LIGHT INTENSITY OF THE PRECIPITATION
MAY PLAY MORE OF A ROLE, WITH EVEN DEPENDING ON HOW THE BOUNDARY
LAYER BEHAVES. FOR NOW WE WILL FAVOR SLIGHT CHC POPS FOR A WEAK
OVERRUNNING POTENTIAL AND GO RAIN AND/OR SNOW.
FOR TUESDAY...THE AFOREMENTIONED FRONT RUNNER WEAKER SURFACE WAVE
SHOULD SCOOT OUT TO SEA EARLY TUESDAY AS THE SHORT WAVE TROUGH MAY
END UP DAMPENING OUT SOME. WHILE THERE COULD BE SOME RESIDUAL LIGHT
PRECIPITATION AROUND TO START TUESDAY, WE SIMPLY FAVORED SLIGHT CHC
POPS IN THE MORNING GIVEN LOWER CONFIDENCE ON TIMING AND OF ANY MORE
ORGANIZED LIFT.
FOR WEDNESDAY AND THURSDAY...THE PATTERN ONCE AGAIN STARTS TO REALLY
RAMP UP WEDNESDAY AS ENERGY FROM THE FOUR CORNERS REGION SLIDES
ACROSS THE PLAINS AND THEN THE TENNESSEE VALLEY. THERE IS ANOTHER
SYSTEM UP IN THE CANADIAN MARITIMES OVERALL, WHICH WOULD TEND TO
LEAD TO BLOCKING. THIS DEVELOPING PATTERN IS LOOKING MORE CONDUCIVE
FOR A COASTAL STORM TO OCCUR. IN THIS UPCOMING POTENTIAL, THE
INITIAL SURFACE LOW MAY TRACK UP THE OHIO VALLEY BUT THEN WEAKEN.
HIGH PRESSURE POSITIONED OVER EASTERN CANADA, IF IT CAN BE
MAINTAINED, MAY HELP TO WEDGE A COLDER LOW-LEVEL AIRMASS SOUTHWARD
ACROSS AT LEAST PORTIONS OF OUR AREA. THIS COLD AIR DAMMING SCENARIO
WOULD OPEN THE DOOR FOR SURFACE LOW REDEVELOPMENT NEAR THE VIRGINIA
COAST AS THE BAROCLINICITY TIGHTENS UP DUE TO THE THERMAL GRADIENT
INCREASING. THIS WOULD PROBABLY ALLOW FOR SOME WARMING ESPECIALLY
ALOFT UNTIL THE MAIN STORM GETS GOING OFF OR ALONG THE COAST.
THEREFORE, CLOUDS INCREASE WEDNESDAY AND WE WENT WITH 40-50 POPS FOR
NOW AS THE POTENTIAL IS THERE FORE A DECENT STORM. WE HELD OFF ON
GOING WITH LIKELY POPS DUE TO ENOUGH MODEL UNCERTAINTY REGARDING
TIMING AND ESPECIALLY THE DETAILS. WE WENT WITH RAIN AND/OR SNOW FOR
THE PRECIPITATION TYPE AS ANY OTHER FROZEN/FREEZING PRECIPITATION IS
MORE DEPENDENT ON THE ACTUAL THERMAL STRUCTURES.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THE 00Z TAFS CONTINUED THE DECENT INTO IFR AND LIFR AS THE
HEAVIER RAIN MOVES IN TONIGHT WITH THE LOWEST CONDITIONS AFTER
MIDNIGHT. WE ALSO CONTINUED THE MENTION OF LLWS. THE GRADIENT EAST
TO SOUTHEAST WIND ITSELF WILL ALSO INCREASE AND GUSTS TO AROUND 40
KTS ARE POSSIBLE AT TERMINALS AND AIRPORTS CLOSER TO THE OCEAN IN
NEW JERSEY AND DELAWARE.
THE COLD FRONT IS EXPECTED TO MOVE THROUGH FROM SOUTHWEST TO
NORTHEAST ACROSS OUR CWA WITH PASSAGE TIME PLUS OR MINUS OF 12Z
BY A COUPLE OF HOURS. RAPID IMPROVEMENT TO MVFR IF NOT VFR
CONDITIONS IS THEN FORECAST. WINDS THOUGH WILL REMAIN BLUSTERY,
BUT THIS TIME FROM THE WEST. CIGS SHOULD IMPROVE TO VFR BY LATE IN
THE MORNING. WINDS WILL REMAIN BRISK THROUGH THE DAY. PEAK GUSTS
OF AROUND 30 KTS ARE LIKELY.
OUTLOOK...
FRIDAY NIGHT AND SATURDAY...MAINLY VFR. WEST-NORTHWEST WINDS
SUSTAINED 15-25 KNOTS WITH GUSTS TO AROUND 35 KNOTS. THE STRONGER
WINDS SHOULD OCCUR DURING THE DAY SATURDAY. THERE COULD BE SOME
SUB-VFR CONDITIONS IN LOCAL/BRIEF SNOW SHOWERS ESPECIALLY FROM THE
KABE AND KRDG TERMINALS NORTH AND WEST.
SUNDAY...VFR WITH NORTHWESTERLY WINDS MAINLY 10-20 KNOTS.
MONDAY AND TUESDAY...VFR MONDAY ALTHOUGH CLOUDS SHOULD INCREASE AND
LOWER SOME. A WEAKER SYSTEM MAY MOVE THROUGH MONDAY NIGHT INTO
TUESDAY WITH THE CHANCE OF SOME LIGHT PRECIPITATION. LIGHT WINDS
MONDAY BECOME NORTHERLY NEAR 10 KNOTS TUESDAY.
&&
.MARINE...
A STRONG COLD FRONT WILL TRACK ACROSS OUR REGION EARLY TOMORROW
MORNING. GALES REMAIN IN PLACE FROM 700 PM TONIGHT, THROUGH THE
SHORT TERM PERIOD, AND INTO THE OUTLOOK PERIOD. SOUTHEAST WINDS
TONIGHT WILL BECOME SOUTHWEST TOMORROW. SEAS WILL RESPOND AND COULD
REACH DOUBLE DIGITS. RAIN OVERNIGHT TONIGHT WILL BECOME MOE SHOWERY
TOMORROW.
OUTLOOK...
A POTENT STORM IS FORECAST TO BE TO OUR NORTH FRIDAY NIGHT THROUGH
SATURDAY BEFORE SHIFTING INTO THE CANADIAN MARITIMES DURING THE
WEEKEND. A TIGHT PRESSURE GRADIENT IN COMBINATION WITH CAA WILL
ALLOW FOR STEEPER LOW-LEVEL LAPSE RATES AND EFFICIENT VERTICAL
MIXING. THE GFS 925 MB WINDS ARE MUCH STRONGER COMPARED TO THE NAM
AND ECMWF, HOWEVER ALL POINT TO GALE FORCE WINDS OCCURRING. THE GFS
WOULD SUGGEST A CHC FOR A PERIOD OF STORM FORCE GUSTS. WE ARE NOT
ALL THAT CONFIDENT REGARDING STORMS, THEREFORE WE WILL CONTINUE WITH
THE GALE WARNING THROUGH THE DAY SATURDAY. THE WINDS SHOULD START
DIMINISHING SATURDAY NIGHT, THEREFORE WE DECIDED NOT TO EXTEND THE
GALE WARNING ATTM. THERE SHOULD BE A PERIOD OF SMALL CRAFT ADVISORY
CONDITIONS FOLLOWING THE GALES INTO ABOUT SUNDAY. A WEAK SYSTEM MAY
THEN MOVE THROUGH MONDAY NIGHT INTO TUESDAY, HOWEVER THE WINDS AND
SEAS ARE ANTICIPATED TO BE BELOW ADVISORY CRITERIA.
&&
.TIDES/COASTAL FLOODING...
THE STRENGTHENING SOUTHEAST FLOW WILL ALLOW WATER TO PILE UP ALONG
THE COASTAL SECTIONS OF THE OCEAN...DELAWARE BAY AND CHESAPEAKE
BAY TONIGHT AND FRIDAY MORNING.
THE LATEST NUMERICAL GUIDANCE IS SHOWING THAT REEDY POINT WILL
REACH MODERATE TIDAL FLOODING WITH THE UPCOMING HIGH TIDE...A
COASTAL FLOOD WARNING HAS BEEN ISSUED. IT DOESNT APPEAR THAT THE
HIGHEST LEVELS WILL CARRY UP INTO THE TIDAL DELAWARE RIVER AT THIS
TIME...SO THE ADVISORY WILL CONTINUE THERE.
THE HIGHER DEPARTURES HAVE COME TOO LATE FOR THE HIGH TIDE AT THE
SHORE AND THE LOWER DELAWARE BAY...SO ADVISORY TYPE WATER LEVELS
ARE EXPECTED THERE...THE ONGOING CF.A WILL CONTINUE.
AS FOR THE CHESAPEAKE BAY, CURRENT DEPARTURES ARE INCREASING...BUT
THE NEXT HIGH TIDE WILL NOT OCCUR UNTIL LATER FRIDAY MORNING INTO
THE EARLY AFTERNOON HOURS...IT APPEARS THAT THE DEPARTURES WILL BE
FALLING BY THEN. BASED ON OUR NEW ADVISORY CRITERIA OF 3.8 FEET
BOTH CAMBRIDGE AND TOLCHESTER BEACH WOULD NEED AROUND A +2.5 FOOT
DEPARTURE TO REACH THE MINOR THRESHOLD. THIS COULD BE OUT OF REACH
BY THEN. WE WILL CONTINUE TO MONITOR.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...COASTAL FLOOD ADVISORY UNTIL 11 AM EST THIS MORNING FOR PAZ070-
071.
NJ...WIND ADVISORY UNTIL 9 AM EST THIS MORNING FOR NJZ001-008-010-
012>014-016-020>027.
COASTAL FLOOD ADVISORY UNTIL 8 AM EST THIS MORNING FOR
NJZ012>014-020-022>027.
COASTAL FLOOD WARNING UNTIL 8 AM EST THIS MORNING FOR NJZ016-
021.
COASTAL FLOOD ADVISORY UNTIL 11 AM EST THIS MORNING FOR
NJZ017>019.
DE...WIND ADVISORY UNTIL 9 AM EST THIS MORNING FOR DEZ001>004.
COASTAL FLOOD ADVISORY UNTIL 8 AM EST THIS MORNING FOR DEZ003-
004.
COASTAL FLOOD WARNING UNTIL 8 AM EST THIS MORNING FOR DEZ001-
002.
MD...WIND ADVISORY UNTIL 9 AM EST THIS MORNING FOR MDZ015-019-020.
MARINE...GALE WARNING UNTIL 7 PM EST SATURDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GIGI/KRUZDLO
SHORT TERM...KRUZDLO
LONG TERM...GORSE
AVIATION...GIGI/GORSE
MARINE...GORSE/KRUZDLO
TIDES/COASTAL FLOODING...HEAVENER/O`HARA
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1240 AM EST FRI DEC 21 2012
...HIGH WIND WARNING FOR LAKE MOULTRIE THROUGH 7 AM EST...
.SYNOPSIS...
A STRONG COLD FRONT WILL CROSS THE AREA OVERNIGHT. MUCH COOLER AND
DRIER WEATHER WILL FOLLOW THE FRONT AS HIGH PRESSURE BUILDS OVER THE
REGION THROUGH THE WEEKEND. UNSETTLED WEATHER WILL THEN RETURN BY
THE MIDDLE OF NEXT WEEK AS AN AREA OF LOW PRESSURE DEVELOPS TO OUR
WEST.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE COLD FRONT HAS PUSHED OFFSHORE AND WITH IT THE RISK FOR
MEASURABLE RAINFALL. SATELLITE SHOWS A CLEARING LINE MOVING
RAPIDLY FROM WEST-EAST WHICH WILL CLEAR THE COAST SOON. WINDY
CONDITIONS WILL PERSIST OVERNIGHT WITH 25-35 MPH WITH GUSTS TO
40-45 MPH. A WIND ADVISORY REMAINS IN EFFECT.
LAKE WINDS...WINDS AT PNOS1 ARE STEADILY INCREASING WITH THE
INITIATION OF STRONG COLD AIR ADVECTION. RAP BOUNDARY LAYER PROGS
MATCHED CURRENT OBSERVATIONS WELL AND SHOW WINDS INCREASING TO 35
KNOTS OVER THE NEXT FEW HOURS. THIS SHOULD TRANSLATE TO HIGH WIND
WARNING CRITERIA AS MIXING PROFILES IMPROVE SO HAVE HOISTED A
WARNING FOR THE LAKE THROUGH 7 AM. THE HIGH WIND WARNING
SUPERSEDES THE WIND ADVISORY FOR INLAND BERKELEY COUNTY...BUT
WARNING LEVEL WINDS WILL ONLY BE OBSERVED ON THE LAKE.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/...
MUCH COLDER AIRMASS TO MOVE INTO THE AREA THIS PERIOD WITH
TEMPERATURES BELOW NORMAL UNTIL POSSIBLY SUNDAY. THE COMBINATION OF
STRONG COLD AIR ADVECTION AND LOW-LEVEL WINDS AS WELL AS A TIGHT
PRESSURE GRADIENT WILL LEAD TO WINDY CONDITIONS FRIDAY WHEN GUSTS
WILL BE AROUND 40 MPH. THUS...HAVE RAISED A WIND ADVISORY FOR ALL
AREAS WITH THE STRONGEST WINDS MOST LIKELY NEAR THE COAST AND ON THE
ELEVATED BRIDGES AND OVERPASSES. TEMPERATURES WILL LIKELY STRUGGLE
INTO THE MID 50S FRIDAY GIVEN THE COLD ADVECTION WITH THE COLDEST
TEMPERATURES LIKELY COMING FRIDAY NIGHT FOR MOST LOCALES WITH
FREEZING TEMPERATURES CLOSE TO THE COAST BY SATURDAY MORNING...AND
WIND CHILLS IN THE MID 20S WITH A CONTINUED BREEZE THROUGH THE
NIGHT.
SHOULD SEE SLIGHTLY WARMER TEMPERATURES SATURDAY EVEN AFTER A COLD
START WITH HIGHS IN THE MID/UPPER 50S. IT WILL LIKELY BE BREEZY
AGAIN BUT MUCH LESS SO THAN FRIDAY. ANOTHER PRETTY COLD NIGHT IS
THEN EXPECTED SATURDAY NIGHT WITH GOOD RADIATIONAL COOLING CONDITIONS
IN PLACE AS SURFACE HIGH PRESSURE SLIDES IN FROM THE WEST. SOME
INLAND LOCALES COULD GET AS COLD OR EVEN COLDER THAN FRIDAY NIGHT
WITH MOST PLACES AWAY FROM THE COAST EXPECTED TO SEE FREEZING
TEMPERATURES AGAIN. THE WARMING TREND WILL CONTINUE SUNDAY AS HIGH
PRESSURE SLIDES JUST SOUTH OF THE AREA ALLOWING TEMPERATURES TO GET
BACK CLOSER TO NORMAL...AROUND 60 DEGREES.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
COOL AND DRY CONDITIONS WILL PERSIST THROUGH MONDAY AS HIGH PRESSURE
REMAINS CENTERED OVER THE SOUTHEAST. A GRADUAL WARMING IS THEN
ANTICIPATED AS A LOW PRESSURE SYSTEM DEVELOPS OVER THE SOUTH CENTRAL
UNITED STATES. OVERALL TEMPS SHOULD WARM INTO THE LOW/MID 60S MONDAY
AND TUESDAY AS A WARM FRONT DEVELOPS AND EXTENDS EAST OVER THE DEEP
SOUTH. MOISTURE LOOKS TO INCREASE THROUGH MIDWEEK AS THE WARM FRONT
LIFTS NORTH THROUGH THE FORECAST AREA...THUS SUPPORTING A SLIGHT
CHANCE OF SHOWERS TUESDAY AFTERNOON. EXPECT TEMPS TO REACH THE UPPER
60S WITHIN THE WARM SECTOR WEDNESDAY BEFORE THE LOW PRESSURE SYSTEM
TRACKS THROUGH THE OHIO VALLEY. A SOUTHWARD EXTENDING COLD FRONT
ASSOCIATED WITH THIS SYSTEM SHOULD EVENTUALLY SWING THROUGH THE
SOUTHEASTERN UNITED STATES LATE WEDNESDAY INTO EARLY THURSDAY. A
CHANCE OF SHOWERS AND/OR THUNDERSTORMS ARE POSSIBLE AS THE FRONT
PROGRESSES TOWARDS THE ATLANTIC LATE IN THE PERIOD.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
VFR. VERY GUSTY WINDS WILL IMPACT THE TERMINALS FOR THE NEXT 18
HOURS. WINDS WILL SUBSIDE AFTER SUNSET THIS EVENING.
EXTENDED AVIATION OUTLOOK...THERE ARE NO CONCERNS AT THIS TIME.
&&
.MARINE...
TONIGHT...WINDS BECOMING WEST BEHIND THE COLD FRONT. SEAS HAVE
INCREASED SIGNIFICANTLY THIS EVENING SO ACCOUNTED FOR THAT ON THIS
UPDATE. AFTER THE COLD FRONT MOVES THROUGH CONDITIONS WILL
CONTINUE TO DETERIORATE IN THE COLD AIR ADVECTION BEHIND THE
FRONT. WITH GOOD MIXING OVER THE RELATIVELY WARM WATERS...GALE
WARNINGS ARE UP FOR ALL WATERS INCLUDING THE CHARLESTON HARBOR.
THE STRONGEST WINDS WILL OCCUR OVER THE CHARLESTON COUNTY WATERS
AND THE OUTER GEORGIA WATERS WHERE GUSTS TO 40 KTS...AND PERHAPS
EVEN 45 KTS FOR A BRIEF TIME ARE POSSIBLE. THE CHARLESTON HARBOR
MAY ALSO SEE GUSTS TO 40 KTS FOR A FEW HOURS JUST BEHIND THE
FRONT. SEAS WILL BUILD RAPIDLY TONIGHT AS WELL. EXPECT SEAS 6-9 FT
FOR THE CHARLESTON COUNTY WATERS...AND 4 TO 7 FOR ALL OTHER
NEARSHORE WATERS. THE HIGHEST SEAS WILL BE BEYOND 20 NM...IN THE
9-12 FT RANGE.
FRIDAY THROUGH TUESDAY...DANGEROUS MARINE CONDITIONS ARE EXPECTED
FRIDAY INTO FRIDAY NIGHT DUE TO THE CONTINUATION OF A TIGHT PRESSURE
GRADIENT IN PLACE ALONG WITH A FAVORABLE ENVIRONMENT TO MIX DOWN
STRONG LOW-LEVEL WINDS TO THE SURFACE...ESPECIALLY ACROSS THE WARMER
WATERS BEYOND 20 NM FROM SHORE. GALES ARE LIKELY THROUGH FRIDAY
EVENING ACROSS THE CHARLESTON COUNTY COASTAL WATERS AND THROUGH
FRIDAY NIGHT ACROSS THE OFFSHORE WATERS WITH THE POTENTIAL FOR
ANOTHER SURGE IN LOW-LEVEL WINDS. CONDITIONS SHOULD IMPROVE SATURDAY
AS THE PRESSURE GRADIENT AND COLD ADVECTION BEGIN TO WANE WITH NO
HEADLINES EXPECTED BEYOND SATURDAY AFTERNOON...ESPECIALLY ACROSS THE
NEARSHORE WATERS. FAIRLY TRANQUIL CONDITIONS THEN EXPECTED LATER IN
THE WEEKEND INTO EARLY NEXT WEEK AS HIGH PRESSURE MOVES INTO THE
AREA.
&&
.TIDES/COASTAL FLOODING...
STRONG OFFSHORE WINDS WILL RESULT IN BELOW NORMAL TIDES BEGINNING
TONIGHT. THE LOWEST TIDES WILL LIKELY OCCUR WITH LOW TIDE FRIDAY
MORNING WHERE LEVELS COULD DROP AS LOW AS -1.0 TO -2.0 MLLW.
TIDE LEVELS THIS LOW WILL LIKELY RESULT IN SOME PROBLEMS FOR
NAVIGATION..ESPECIALLY IN THE MORE TYPICAL SHALLOW AREAS. BELOW
NORMAL TIDES WILL LINGER THROUGH THE WEEKEND WITH LONG-DURATION
OFFSHORE WINDS EXPECTED.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR GAZ087-088-
099>101-114>119-137>141.
SC...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR SCZ040-042>044-
047>052.
HIGH WIND WARNING UNTIL 7 AM EST THIS MORNING FOR SCZ045.
MARINE...GALE WARNING UNTIL 5 AM EST EARLY THIS MORNING FOR AMZ330-352-
354.
GALE WARNING UNTIL MIDNIGHT EST TONIGHT FOR AMZ350.
GALE WARNING UNTIL 5 AM EST SATURDAY FOR AMZ374.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
134 AM EST FRI DEC 21 2012
.AVIATION...
06Z TAFS...THERMAL RIDGE WRAPPING AROUND WESTERN FRINGE OF
MID/UPPER LEVEL THROUGH ALLOWED FOR A CHANGEOVER TO RAIN AT
KSBN...AND EVEN BRIEFLY AT KFWA. PRECIP HAS SWITCHED BACK TO SNOW
AT KSBN AND EXPECTING SNOW TO PREVAIL AT BOTH TERMINALS THROUGH
THE REMAINDER OF THE NIGHT WITH ANY LINGERING RAIN OR RAIN/SNOW
MIX CONFINED CLOSER TO LAKE MICHIGAN. IFR CIGS SHOULD PREVAIL AT
TERMINALS WITH LIFR CONDITIONS POSSIBLE LATE TONIGHT AS SNOW AND
BLOWING SNOW BECOMES MORE PREVALENT OVERNIGHT AS LAKE ENHANCEMENT
INCREASES. POSSIBLE EARLY MORNING LIFR/IFR CONDITIONS SHOULD
IMPROVE TO MVFR TOWARD MIDDAY AS DEFORMATION BAND SHIFTS WELL EAST
OF THE AREA WITH LINGERING LAKE EFFECT SNOW SHOWERS PENETRATING
WELL INLAND WITH STRONG BACKGROUND WIND FIELD. IN TERMS OF
WINDS...PRESSURE RISE BUBBLE WILL CONTINUE TO TRACK ACROSS
NORTHEAST INDIANA NEXT FEW HOURS GIVING A SHORT HALF HOUR WINDOW
OF GUSTS TO 40 TO 45 KNOTS BEFORE RELAXING MORE INTO THE 35 TO 40
KNOT RANGE. WIND GUSTS TO INCREASE MID MORNING BACK INTO THE 40 TO
45 KNOT RANGE WITH EVEN SOME HIGHER GUSTS POSSIBLE AT KSBN THROUGH
MIDDAY.
&&
UPDATE...
MESOSCALE DVLPMNTS LT THIS AFTN IN COMBO W/MOST RECENT HIGHRES MODEL
GUIDANCE ALL POINTING TO SIG SNOW/WIND SPREADING EWD ACRS CWA
OVERNIGHT W/WIDESPREAD MOD-HVY SNOW NOTED OVR MUCH OF WRN/CNTRL IL. IN
FACT RECENT HRRR/RUC GUIDANCE INDICATING BRUTE WRAPPED UP MID LVL
CIRC NR KLAF HAS NOT YET PEAKED AND QUITE EVIDENT WITHIN
REINTENSIFYING DEFORMATION ZONE EXTENDING FM CNTRL IL NNE UP ACRS
WRN LK MI. IN FACT 21Z RUC DOES NOT BOTTOM H7 LOW UNTIL 12Z NR
WINDSOR ONTARIO. AS SUCH AND PER RAPID ESCALATION OF GRADIENT WINDS
WILL INITIALLY EXPAND WARNING SWD TO ENCOMPASS STARKE/MARSHALL AND
PLACE PULASKI/FULTON WITHIN HIGHER GRADED ADVISORY. FURTHER
EXPANSION OF WARNING PSBL FURTHER EAST BUT WILL CLOSELY
MONITOR CONTD EWD DVLPMNT/TRANSLATION OF DEFORMATION BAND AND
INCIPIENT LK ENHANCEMENT TWD 03-04Z ALG W/ADDNL 00Z BASED GUIDANCE
FOR CLUES.
PREV DISCUSSION... /ISSUED 404 PM EST THU DEC 20 2012/
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
LONGWAVE PATTERN HAS UNDERGONE TREMENDOUS AMPLIFICATION OVER THE
PAST 24 HOURS WITH POSITIVE FEEDBACK MECHANISMS FROM DEVELOPING
STORM PROMOTING STRONG RIDGING OVER THE EAST COAST. NOT TOO
SURPRISING THEN THAT THE LATEST 12Z GUIDANCE HAS TRENDED A TOUCH
FURTHER NORTHWEST WITH THE LOW TRACK...A SHIFT THAT HAS BEEN LARGELY
ANTICIPATED IN THE PAST FEW DISCUSSIONS AND REQUIRES LITTLE CHANGE
TO THE OVERALL FORECAST. LATEST SURFACE ANALYSIS SHOWS 983MB LOW
OVER CHICAGO AT PRESS TIME. LITTLE FURTHER DEEPENING IS EXPECTED AS
THE OCCLUSION PROCESS IS NOW UNDERWAY WITH A MATURE TROPOPAUSE FOLD
MOVING OVERHEAD LATER THIS EVENING. SURFACE LOW WILL CONTINUE TO
DRIFT NORTHEAST INTO LOWER MI DURING THE EVENING BEFORE CYCLONIC
SHEAR MAX PROPAGATES THROUGH THE BASE OF THE TROUGH AND FORCES
SECONDARY SURFACE LOW DEVELOPMENT OVER THE EAST COAST. MIDLEVEL DRY
SLOT HAS FILLED IN RATHER QUICKLY THIS AFTERNOON THANKS TO THE
IMPRESSIVE CVA ALOFT. EXPECT THIS TO CONTINUE AS THE LOW LEVEL
DEFORMATION AXIS PIVOTS INTO OUR CWA. TIMING OF TRANSITION TO SNOW
REMAINS A TOP CONCERN. SHARP RAIN/SNOW LINE IS CURRENTLY DRAPED OVER
CENTRAL IL WITH GOOD PUSH OF CAA FORCING A QUICK CHANGEOVER. SURFACE
WET BULBS LOOK TO REMAIN ABOVE FREEZING THROUGH ROUGHLY 03Z OVER
MOST OF OUR CWA. THIS MAY BE PARTIALLY OFFSET BY DYNAMIC COOLING
PROCESSES BUT EXPECT MOST AREAS WONT SEE ANY SNOW UNTIL ROUGHLY
01-02Z. THIS TRANSITION MAY TAKE EVEN LONGER OVER THE NORTHWEST WITH
CYCLONICALLY WRAPPED THERMAL TONGUE SLOW TO ERODE AND POSSIBLE
AIRMASS MODIFICATION NEAR THE LAKE.
STRONG WINDS WILL LIKELY BE THE BIGGEST STORY. IMPRESSIVE
ISALLOBARIC COMPONENT OVER THE REGION WILL WEAKEN SOMEWHAT AS THE
SURFACE LOW BEGINS TO FILL OVERNIGHT. HOWEVER...PROPAGATION OF THE
STILL VERY RESPECTABLE SURFACE LOW COMBINED WITH INCREASING CAA
PROMOTING DECENT LOW LEVEL INSTABILITY WILL SUPPORT STRONG WINDS.
925MB WINDS WILL BE APPROACHING 50 KTS BY TOMORROW MORNING AND THIS
SHOULD HAVE LITTLE DIFFICULTY MIXING TO THE SURFACE. EXPECT WIND
GUSTS UP TO 50 MPH LATE TONIGHT INTO TOMORROW MORNING...SUPPORTED BY
UPSTREAM OBS. IN FACT...ALREADY STARTING TO SEE SOME 40-45 MPH GUSTS
ALONG/BEHIND SURFACE BOUNDARY PASSING THROUGH THE AREA. CONTEMPLATED
GOING WITH HIGH WIND WARNING BUT HAVE ONLY SEEN A COUPLE 50+ KT
GUSTS UPSTREAM AND WHILE THIS MAY BE POSSIBLE NEAR THE
LAKESHORE...EXPECT MOST ARES TO STAY LARGELY BELOW WARNING CRITERIA.
QPF/SNOW FORECAST REMAINS TENUOUS. BEST LOW-MIDLEVEL DEFORMATION AND
ASSOCIATED FGEN RESPONSE CURRENTLY CAUSING HEAVY SNOW OVER NORTHERN
ILLINOIS AND SOUTHERN WISCONSIN WILL PASS LARGELY NORTHWEST OF OUR
AREA ALONG WITH THE TROWAL AXIS. THIS SYNOPTIC FORCING MAY CLIP OUR
NORTHWEST ZONES BUT SNOW AMOUNTS IN OUR CWA WILL BE HIGHLY DEPENDENT
ON DUBIOUS LAKE RESPONSE. PLENTY OF SYNOPTIC MOISTURE THROUGHOUT THE
COLUMN. INSTABILITY PARAMETERS ARE ALSO SUFFICIENT...AT LEAST BY
EARLY FRIDAY MORNING...WITH DELTA T`S IN THE MID TEENS AND
EQUILIBRIUM LEVELS CLIMBING TO AROUND 9 KFT BUT STRONG 850MB WINDS
REMAIN A CONCERN. NOT ONLY WILL THIS POTENTIALLY DISRUPT BAND
ORGANIZATION BUT THE MORE IMPORTANT IMPACT OF STRONG LOW LEVEL WINDS
MAY BE TREMENDOUS FRACTURING OF SNOWFLAKES...FORCING RELATIVELY LOW
SNOW RATIOS. NAM BUFR SOUNDINGS SUGGEST LAKE EFFECT SNOW WILL NOT
BEGIN IN EARNEST UNTIL AFTER 06Z TONIGHT WITH THE REAL COLD AIR PUSH
AND WILL TAPER OFF BY MIDDAY TOMORROW. QPF DURING THIS TIME LOOKS TO
BE AROUND 0.4 INCHES FOR OUR NORTHWEST COUNTIES. ASSUMING WE MANAGE
TO GET A 10:1 RATIO...THIS WILL RESULT IN MAINLY 3-5 INCHES WITH A
FEW ISOLATED HIGHER AMOUNTS. LAKE ENHANCED BANDS WILL LIKELY MAKE
FOR HIGHLY VARIABLE SNOW AMOUNTS...FURTHER EXACERBATED BY
DIFFICULTIES MEASURING SNOW IN HIGH WIND. AMOUNTS FURTHER DOWNSTREAM
WILL BE SLIGHTLY LOWER...THOUGH WITH THE VERY STRONG LOW LEVEL
FLOW...BANDS WILL LIKELY PENETRATE MUCH FURTHER INLAND THAN NORMAL.
HIGHEST SNOWFALL AMOUNTS MAY ACTUALLY END UP BEING FURTHER
DOWNSTREAM THAN THE IMMEDIATE LAKESHORE. NOT CONFIDENT ENOUGH TO
EXPAND WARNING BUT THIS IS SOMETHING THAT WILL NEED TO BE WATCHED.
STRONG WINDS WILL CERTAINLY CAUSE A FAIR AMOUNT OF BLOWING/DRIFTING.
AM A LITTLE CONCERNED THE MODEST SNOW AMOUNTS AND INITIALLY WARM
SURFACE TEMPS MAY LIMIT THE POSSIBILITY OF TRUE WHITEOUT CONDITIONS
BUT NEVERTHELESS EXPECT LARGE IMPACTS DURING THE MORNING COMMUTE AND
WILL MAINTAIN AREAWIDE WINTER WEATHER ADVISORY. SNOW AND HIGH WIND
WILL GRADUALLY TAPER OFF TOMORROW AFTERNOON AS LOW PRESSURE EXITS
THE REGION AND HIGH PRESSURE RETURNS WITH DRY AIR ADVECTION AND
SUBSIDENCE.
LONG TERM...
SATURDAY THROUGH THURSDAY...THE MAIN CHALLENGES THIS PERIOD ARE
DURING THE MIDDLE OF NEXT WEEK WHEN THERE IS THE POTENTIAL FOR
UNSETTLED WEATHER INCLUDING A CHANCE FOR MAINLY SNOW. FOR THIS
PACKAGE...OVERALL VERY POOR RUN TO RUN CONSISTENCY WITH MASS FIELDS
AMONG THE ECMWF AND GFS TENDING TO LOW CONFIDENCE IN THE FORECAST.
AT THIS POINT...FAVOR A GEM/CIPS ANALOG BLEND. THESE SOLUTIONS FAVOR
A MORE NORTHWEST TRACK OF THE SFC LOW...CLOSER TO THE UPPER LEVEL
SUPPORT. THE GFS IN THIS PATTERN TENDS TO INITIALLY TRACK THE SFC
LOW TOO FAR TO THE SOUTHEAST. THEREFORE...KEPT A HIGH CHANCE FOR
SNOW LATE WEDNESDAY INTO WEDNESDAY NIGHT. THERMAL PROFILES INDICATE
ALL SNOW DURING THIS PERIOD...SO WITH A MORE NORTHWEST TRACK AND
SUFFICIENTLY COLD TEMPERATURES ALOFT...FEEL THAT THERE IS A
REASONABLE CHANCE FOR ACCUMULATING SNOW. OTHERWISE...A WEAKER SYSTEM
WILL MOVE ACROSS THE AREA EARLY THIS WEEK WITH A CHANCE FOR A
RAIN/SNOW MIX MONDAY.
AVIATION...
18Z TAFS...DRY SLOT HAS NOW ENGULFED MOST OF THE AREA
ALTHOUGH SCATTERED SHOWERS ARE STILL BEING OBSERVED ALONG AND
AHEAD OF THE COLD FRONT LOCATED ALONG KLAF TO KIKK LINE. MAJOR
IMPACTS FOR THE REST OF THE DAY WILL BE STRONG SOUTHEASTERLY
WINDS. THESE WINDS WILL ABATE SLIGHTLY...ESPECIALLY AT KSBN...AS
THE LOW PRESSURE CENTER PASSES BY TO THE NORTHWEST. WINDS WILL
SHIFT FROM SOUTHEASTERLY TO SOUTHWESTERLY BEHIND THE FRONT...AND
EVENTUALLY NORTHWESTERLY LATER THIS EVENING AS PRECIPITATION
CHANGES OVER TO SNOW. THESE NORTHWESTERLY WINDS COULD GUST HIGHER
THAN 40 KNOTS BY FRIDAY MORNING. PRECIPITATION WILL CHANGE TO SNOW
BETWEEN 00Z AND 03Z TONIGHT. FALLING SNOW...COUPLED WITH STRONG
WINDS AND POTENTIAL FOR BLOWING SNOW WITH ANY ACCUMULATION THAT
MAY OCCUR WILL LIKELY RESULT IN SERIOUS VIS
RESTRICTIONS...ESPECIALLY BETWEEN 06Z AND 12Z TONIGHT.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
INZ006>009-013-015>018-020-022>027-032>034.
WINTER STORM WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
INZ003>005-012-014.
MI...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
MIZ079>081.
WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ077-078.
OH...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ001-
002-004-005-015-016-024-025.
LM...STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR LMZ043-046.
&&
$$
SHORT TERM...AGD
LONG TERM...SKIPPER
UPDATE...T
AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS GAYLORD MI
145 AM EST FRI DEC 21 2012
.SYNOPSIS...
ISSUED AT 414 PM EST THU DEC 20 2012
STRONG LOW PRESSURE OVER THE SOUTHERN GREAT LAKES...WILL CONTINUE TO
LIFT INTO SOUTHERN MICHIGAN...GENERATING CONTINUED WINTRY WEATHER
ACROSS NORTHERN MICHIGAN THROUGH FRIDAY. PERIODS OF HEAVY SNOW IS
EXPECTED FOR AREAS OF NORTHERN MICHIGAN THROUGH FRIDAY AFTERNOON.
ANY PRECIPITATION FALLING AS RAIN OR A RAIN....SNOW MIX WILL CHANGE
OVER TO SNOW THIS EVENING. WINDS WILL INCREASE TONIGHT AND CONTINUE
THROUGH FRIDAY.
&&
.UPDATE...
ISSUED AT 135 AM EST FRI DEC 21 2012
QUITE THE STORM ON OUR HANDS. WARM NOSE/TROWAL STILL SITTING
ACROSS NE LOWER WITH RAIN AND RAIN/SNOW FROM ROUGHLY ALPENA TO
WEST BRANCH.THIS WILL CHANGE OVER TO JUST SNOW OVER THE NEXT
HANDFUL OF HOURS. MEANWHILE...DIFFLUENT UPPER AIR PATTERN WITHIN
DEFORMATION AXIS AND PERSISTENT LOW LEVEL WARM/MOIST ADVECTION
UNDERNEATH IT...WILL PROVIDE FOR ENHANCED SNOWFALL RATES FOR THE
NEXT FEW HOURS. LATEST SPENES DETAILS SUGGEST SNOWFALL RATES OF UP
TO 3"/HR FROM MISSAUKEE COUNTY THROUGH GAYLORD AND ROGERS CITY.
THIS ONLY EXACERBATES THE HEAVY (AND I MEAN HEAVY...WITH LIQUID)
SNOWS THAT HAVE ALREADY FALLEN AND SNAPPED TREE LIMBS AND TREES.
WILL INCREASE OVERNIGHT SNOWFALL AND QPF IN THIS REGION. SOME
LOCALES LIKELY TO EXCEED 20" BY DAYBREAK.
UPDATE ISSUED AT 1053 PM EST THU DEC 20 2012
WOW...VERY IMPRESSIVE STORM UNFOLDING ACROSS THE REGION WITH
SURFACE LOW NEAR GLADWIN ATTM AND SLOWLY LIFTING NORTHEAST. OVER
THE LAST HOUR...HAVE NUMEROUS REPORTS OF THUNDER...3 INCHES OF
SNOW IN ONE HOUR AT PETOSKEY...AND EXPANDING POWER OUTAGES ACROSS
NORTHERN LOWER...NOT SURPRISING GIVEN THE HEAVY NATURE OF THE SNOW
ALONG WITH NUMEROUS REPORTS OF BRANCHES/TREES DOWN. EXPECT THAT WE
HAVE ANOTHER 2-4 HOURS BEFORE RATES BEGIN TO COME DOWN...WHICH
WILL LIKELY BRING TOTALS ABOVE 15" IN A FEW SPOTS /ESP OTSEGO
COUNTY/. RAIN/SNOW LINE IS STEADILY ADVANCING EAST /NOW SNOWING AT
PZQ/..AND WILL CONTINUE TO DO SO AS THE LOW PROGRESSES EAST.
LITTLE CHANGES NECESSARY TO THE GOING FORECAST...WITH SOME UPPED
SNOW TOTALS BASED ON EVENING OBSERVATIONS. WINDS WILL GET GOING
AFTER MIDNIGHT AS WELL...UNFORTUNATELY EXACERBATING AN ALREADY
HAZARDOUS SITUATION. IF YOU MUST BE OUT...USE EXTREME CAUTION!
UPDATE ISSUED AT 834 PM EST THU DEC 20 2012
LOOKING OUT THE WINDOW HERE AT APX REVEALS MODERATE TO HEAVY
SNOW...WITH RIMED DENDRITES SUGGESTING FAIRLY "WET" SNOW TO
LIQUID RATIOS /7-10:1/...IN AGREEMENT WITH EVENING OBSERVATIONS.
NOT SURPRISINGLY...CURRENT LIGHTNING DATA SHOWS SOME IN CLOUD
FLASHES OVER AND NEAR LITTLE TRAVERSE BAY...WITH A FEW REPORTS OF
THUNDER RECEIVED AT THE OFFICE. VERY HEAVY SNOW HAS NOW DEVELOPED
ALONG A FKS-CVX-MCD LINE WITH 1 INCH+/HOUR RATES PER SPOTTERS. AT
THE SAME TIME...HEAVY SNOWS CONTINUE OVER MUCH OF INTERIOR
NORTHERN LOWER...AND EASTERN UPPER /ESP ALONG I-75 PER SPOTTERS/.
GIVEN THIS EVOLUTION...WILL LEAVE GOING HEADLINES IN PLACE AS OF
THIS TIME. PRIMARY AREA OF CONCERN /OF LESS THAN WARNING LEVEL
SNOWS OVERNIGHT/ IS FROM TVC TO MBL...WHERE A GAP IN THE ECHOES
HAVE DEVELOPED WITH THE BETTER SOUTH-NORTH MOISTURE FEED FURTHER
EAST. STILL EXPECT...HOWEVER...THAT AS WE START TO GET THE LAKE
INVOLVED LATER TONIGHT THAT THIS WILL FILL BACK IN WITH
SIGNIFICANT ACCUMS. WITH WINDS KICKING UP HERE AFTER
MIDNIGHT...EXPECT A VERY HAZARDOUS MORNING COMMUTE...AND THUS THE
WARNING WILL REMAIN.
LOW PRESSURE LOOKS TO HAVE REACHED PEAK INTENSITY WITH OBS OVER
SOUTHWEST LOWER MICHIGAN SHOWING 985MB...HAVING COME UP 1-2 MB IN
THE LAST FEW HOURS. THUS...AS THE OCCLUSION PROCESS GETS
GOING...EXPECT OUR TRANSITION TO A COOLER AIRMASS TO GO AS
EXPECTED...WITH SNOWS COLLAPSING TO THE COAST OF NORTHEAST LOWER
AFTER MIDNIGHT.
UPDATE ISSUED AT 704 PM EST THU DEC 20 2012
TERRIFIC WV SATELLITE PRESENTATION OF OUR WINTER STORM AS H5 LOW
CROSSES THROUGH NORTHERN INDIANA WITH 984 MB LOW EMERGING OVER
SOUTHWEST LOWER MICHIGAN. CLASSIC TRACK TO KEEP NEARLY ALL OF OUR
CWA IN THE DEFORMATION PRECIPITATION THROUGH THE OVERNIGHT. RECENT
TRENDS IN THE DUAL POL PRODUCTS SUGGESTS A TRANSITION BACK TO SNOW IS
COMPLETE FROM MBL TO TVC...WITH VSBY RESTRICTIONS BECOMING GREATER
AT THESE SITES AS THE SNOWFALL INTENSITY INCREASES. A RAIN/SNOW
MIX...OR JUST PLAIN RAIN CONTINUES FROM CAD TO HTL TO APN WITH
ROGERS CITY SHIFTING TO RAIN LAST HOUR. THIS LINES UP FAIRLY WELL
WITH RECENT RAP TRENDS...WITH NEW APX RAOB SHOWING THE RAP IS
ABOUT 1C TOO WARM THROUGH THE LLEVELS. THUS...HAVE ONLY NEEDED
SOME MINOR TWEAKS TO THE WEATHER GRIDS FOR THE NEXT FEW HOURS.
PRECIPITATION RATES LOOK TO REMAIN IMPRESSIVE WITH CONVECTIVE
ELEMENTS CONTINUING TO FEED THE DEFORMATION BAND.
THEREFORE...OCCASIONAL 1-2"/HOUR SNOWFALL RATES LOOK PLAUSIBLE
THROUGH AT LEAST 06Z...AND THUS OVERNIGHT SNOWFALL AMOUNTS OF 6"+
FOR FAR NORTHERN LOWER AND EASTERN UPPER STILL LOOK GOOD. A
TERRIBLE TRAVEL NIGHT FOR SURE...WITH SOME POWER OUTAGES REPORTED
/AND LIKELY TO CONTINUE AND PERHAPS EXPAND AS WINDS GET GOING
AFTER MIDNIGHT/.
UPDATE ISSUED AT 556 PM EST THU DEC 20 2012
LOW PRESSURE CROSSING SOUTHERN LAKE MICHIGAN AT THIS HOUR...NEAR
983 MB /STILL A LITTLE BELOW NEAR TERM RUC GUIDANCE/. RAIN-SNOW
LINE HAS BEEN FLIRTING WITH THE TVC-GOV-APN CORRIDOR AND THIS IS
IN GOOD AGREEMENT WITH H8 WETBULB ZERO LINE. EXPECT THAT THIS WILL
SHIFT A LITTLE FURTHER NORTH AND EAST THIS EVENING UNTIL THE LOW
REACHES OUR LONGITUDE AROUND 9-10PM...IN LINE WITH RAP
EXPECTATIONS.
PRIMARY CHANGES INCLUDE REMOVING BLOWING SNOW MENTION THROUGH THE
EVENING UNTIL WE CAN GET THE NNW WINDS TO STRENGTHEN IN
COMBINATION WITH SLOWLY COOLING BL TEMPS. HAVE ALSO ADJUSTED
WEATHER GRIDS TO ACCOUNT FOR EXPECTED MOVEMENT OF THE RAIN/SNOW
LINE. FINALLY...HAVE ADJUSTED OVERNIGHT PRECIPITATION TOTALS PER
LATEST HRRR/RAP...BUT THIS ONLY RESULTS IN A MINOR CHANGE TO
PREVIOUS GRIDDED FORECAST. STILL EXPECT SOME SPOTS OVER INTERIOR
NORTHERN LOWER AND EASTERN UPPER TO SEE UPWARDS OF 6 ADDITIONAL
INCHES OVERNIGHT. WHILE A LITTLE LESS WILL FALL AT THE COASTS...IT
WILL BE FAR MORE THAN HAS BEEN SEEN THUS FAR...THEREFORE CAUSING
TRAVEL CONDITIONS IN THESE REGIONS TO DETERIORATE RAPIDLY.
HAVE ISSUED AN SPS TO HIGHLIGHT THE CHANGING EVENING CONDITIONS.
OTHERWISE...HEADLINES LOOK GOOD. WILL REASSESS OUR FAR SOUTHEAST
FOR POTENTIAL WINTER WEATHER ADVISORY NEEDED WELL AFTER MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
ON THE LATEST SURFACE WEATHER MAP OF INTEREST...984 MB LOW PRESSURE
WAS CENTERED NEAR CHICAGO ILLINOIS. APX AND SURROUNDING RADARS
SHOWED MODERATE TO HEAVY PRECIPITATION ACROSS MUCH OF NORTHERN
MICHIGAN. THE FORM OF WHICH IS ALL OVER THE MAP...SOME SPOTS ACROSS
THE HIGHER TERRAIN HAS HAD 6 INCHES OR MORE...WHILE THE LOWER
ELEVATIONS HAVE HAD 2 INCHES OR LESS (IN SOME CASES NEARLY NONE AT
ALL). FORECAST CHALLENGES ARE NUMEROUS WITH CHANGEOVER TO ALL SNOW
AND ADDITIONAL ACCUMULATIONS THE MAIN ONES.
TONIGHT...STORM SYSTEM WILL CONTINUE TO TRACK NORTHEAST ACROSS LOWER
MICHIGAN TONIGHT THEN INTO WESTERN NEW YORK FRIDAY. SNOWFALL RATES
ARE EXPECTED TO PICK UP ONCE AGAIN AND AS COLDER AIR GETS PULLED
INTO THE REGION FROM THE NORTH...SNOWFALL RATES ARE EXPECTED TO
INCREASE. WATER VAPOR LOOPS DEPICT A WELL-DEFINED BAROCLINIC LEAF
STRUCTURE. ACCOMPANYING STRONG DIVERGENCE WITHIN A COUPLED UPPER JET
STRUCTURE ATOP LOW/MID-LEVEL FRONTOGENESIS WILL SUPPORT AN INCREASE
IN SNOW RATES DURING THE NEXT FEW HOURS. DEEP ASCENT THROUGH
DENDRITIC GROWTH ZONES WITHIN THE 700-500-MB LAYER WILL SUPPORT
EFFICIENT SNOW GROWTH...WITH ISOTHERMAL PROFILES IN THE 850-700-MB
LAYER YIELDING EFFICIENT SNOW AGGREGATION. SNOWFALL RATES OF 1-1.5
INCHES WILL LIKELY BECOME COMMON LATER THIS EVENING...AS ONE OR MORE
NE/SW-ORIENTED SNOW BANDS DEVELOP WHILE THE SFC LOW APPROACHES. THE
ENHANCED SFC PRESSURE GRADIENT WILL SUPPORT NNE TO ENE WINDS OF
20-25 MPH WITH GUSTS REACHING 30 TO OCCASIONALLY 35 MPH. THIS WILL
SUPPORT REDUCED VISIBILITIES TO ONE-HALF MILE IN BLOWING SNOW...AND
LOCALIZED BLIZZARD CONDITIONS MAY OCCUR. ADDITIONAL ACCUMULATIONS
WILL VARY WIDELY FROM AN INCH OR LESS NEAR THE LAKE HURON LAKE
SHORES TO BETWEEN 4 AND 8 INCHES ACROSS EASTERN UPPER AND THE HIGHER
TERRAIN OF NORTHERN LOWER. LOWS RANGING FROM THE MIDDLE 20S NORTH TO
THE LOWER 30S SOUTHEAST.
FRIDAY...WRAP AROUND SNOW SHOWERS IN THE MORNING THEN DRIER
AIR/SUBSIDENCE/RIDGING BY LATE IN THE DAY WHICH SHOULD DIMINISH
ACTIVITY. THERE IS ALSO A BIT OF OVER LAKE INSTABILITY (DELTA TS OF
ABOUT 14) WITH STRONG NORTHERLY FLOW. THIS WILL LEAD TO WIDESPREAD
BLOWING AND DRIFTING SNOW...WITH ONLY ABOUT 2 INCHES OR LESS OF
ADDITIONAL ACTUAL ACCUMULATION. HIGHS IN THE UPPER 20S NORTH TO THE
MIDDLE 30S SOUTHEAST.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
FOUR WAVE NRN HEMISPHERIC PATTERN IN PLACE TODAY WITH MAJOR TROUGH
AXES OVER FAR EASTERN ASIA AND ALONG THE NOAM WEST COAST. SW
FLOW/RIDGING AND RELATIVELY MILD TEMPERATURES EXISTS DOWNSTREAM
THROUGH THE PLAINS AND THE EASTERN CONUS...WITH MUCH OF NRN MICHIGAN
JUST COLD ENOUGH TO GET IN ON THE HEAVY SNOW WITH OUR ONGOING WINTER
STORM (ACTUALLY PARTS OF THE CWA IS WITHIN THE SWEET SPOT...THE
TRANSITION ZONE FROM RAIN TO SNOW WHERE YOU GET MAXIMUM MOISTURE
INFLOW). FLOW PATTERN REMAINS SOMEWHAT PROGRESSIVE ACROSS THE CONUS
THROUGH THE UPCOMING SEVEN DAY STRETCH BUT STILL ON THE OVERALL MILD
SIDE OF THE THINGS AS THE REALLY COLD AIR REMAINS STUCK ACROSS THE
POLE INTO EASTERN ASIA...A PATTERN THAT HAS DOMINATED THIS
FALL/EARLY WINTER SEASON SO FAR. BUT FIRST...HAVE TO GET THROUGH THE
ONGOING STORM.
FRIDAY NIGHT AND SATURDAY...ONGOING STRONG SYSTEM WILL BE EXITING
EAST OF THE STATE BY FRIDAY EVENING WITH MID LEVEL RIDING/SFC HIGH
PRESSURE AND DRIER AIR NOSING INTO THE WESTERN GREAT LAKES THROUGH
THE NIGHT. NNW FLOW LAKE SNOW SHOWERS AND GUSTY WINDS WILL PERSIST
THROUGH FRIDAY EVENING BEFORE DIMINISHING SUBSTANTIALLY OVERNIGHT
INTO THE DAY SATURDAY. ACCORDINGLY...WILL START OUT WITH CATEGORICAL
NNW FLOW LAKE SNOW SHOWERS FRIDAY EVENING BEFORE DIMINISHING/ENDING
BY SATURDAY MORNING. CURR
SATURDAY NIGHT THROUGH CHRISTMAS EVE...A RELATIVE LULL IN THE
WEATHER ACTION FOR THE LATTER HALF OF THE WEEKEND THROUGH CHRISTMAS
EVE WITH BROAD HIGH PRESSURE AND WEDGE OF DRIER AIR IN THE REGION.
THAT SAID...GUIDANCE DOES DEPICT A COUPLE WAVES WITHIN THE FAST NW
FLOW ALOFT SKITING THROUGH THE NRN PART OF THE STATE...ONE SATURDAY
NIGHT AND A STRONGER ONE ON SUNDAY. SOME COLDER AIR SAGGING BACK
INTO THE REGION BEHIND THE WAVE ENOUGH TO MAINTAIN AND/OR GENERATE
SOME LAKE SNOWS OFF THE GREAT LAKES...ESPECIALLY SUNDAY AS THE
STRONGER WAVE PASSES THROUGH. BUT OVERALL NOT A BIG DEAL WITH FAIRLY
DRY AIR IN CONTROL. SUNDAY NIGHT THROUGH CHRISTMAS EVE LOOKING QUIET
AT THIS POINT WITH BROAD HIGH PRESSURE THROUGH THE REGION.
CHRISTMAS DAY THROUGH THURSDAY (EXTENDED PERIODS)...SOLUTION
DIFFERENCES AMONG THE MEDIUM RANGE GUIDANCE...AS USUAL. GEM/GFS
SOLUTIONS ARE IN ONE CAMP KEEPING THINGS ON THE QUIET SIDE FOR
CHRISTMAS DAY (ALTHOUGH THE GFS DOES HAVE A WEAK FAST MOVING WAVE
MOVING THROUGH THE REGION). ECMWF HINTING AT ANOTHER STRONGER STORM
FOR TWO RUNS NOW PUSHING UP THROUGH THE OHIO VALLEY/GREAT LAKES ON
CHRISTMAS DAY. DIFFERENCES AMONG THE GUIDANCE ARE THE RESULT OF THE
DEGREE OF PHASING BETWEEN THE NRN AND SOUTHERN STREAMS WITH OBVIOUS
BIG IMPLICATIONS. NO WAY OF KNOWING THE CORRECT SOLUTION AT THIS
JUNCTURE...BUT WILL HAVE LOWER END SNOW CHANCES ON TUESDAY FOR NOW.
ANOTHER SHOT FOR A STORM SYSTEM MAY COME WEDNESDAY NIGHT THROUGH
THURSDAY WITH THE POTENTIAL FOR YET ANOTHER STORM TO SPIN UP OFF THE
GULF AND LIFT NORTHWARD THROUGH THE EASTERN CONUS. AGAIN...BIG
DIFFERENCES ON THE TIME/TRACK OF THAT STORM (IF IT OCCURS AT ALL).
BUT WILL CARRY CHANCE POPS FOR SNOW DURING THAT TIME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1151 PM EST THU DEC 20 2012
A COMBINATION OF IFR/MVFR CONDITIONS AT THE TAF SITES AT THE
MOMENT AS LOW PRESSURE NEAR TAWAS PUSHES EAST INTO LAKE HURON. ANY
MIX WITH RAIN IS NOW OVER AT APN...WITH SNOW THE ONLY PTYPE
THROUGH THE PERIOD. OCCASIONAL SNOWS WILL CONTINUE THROUGH
DAYBREAK WITH LIFR-IFR VSBYS/IFR CIGS POSSIBLE PARTICULARLY AT
PLN/TVC. RESTRICTIONS WILL GRADUALLY IMPROVE FOR THE DAY ON
FRIDAY...WITH MVFR CIGS/VSBYS IN LAKE EFFECT SHSN/BLOWING SNOW
WITH SOME LATE DAY/EVENING IMPROVEMENT TO VFR AT TVC/MBL.
WINDS HAVE SHIFTED NORTHERLY TO 10G20KTS ATTM AND WILL CONTINUE TO
BACK NORTHWESTERLY AND INCREASE TO 25G35KTS FOR THE DAY ON FRIDAY.
&&
.MARINE...
ISSUED AT 414 PM EST THU DEC 20 2012
MAJOR WINTER STORM LIFTING NE INTO THE GREAT LAKES THROUGH
TONIGHT...BEFORE DEPARTING FRIDAY. OVERLAKE INSTABILITY WITH
EASTERLY WINDS AT 20-35KTS TO DEVELOP AS MODERATE TO HEAVY SNOWS
(MIXED WITH OR ALL RAIN ACROSS LAKE HURON). THE SNOWS WILL BE
INCREASINGLY INTENSE THIS EVENING. WINDS WILL DECREASE SOME ACROSS A
GOOD CHUNK OF THE NEARSHORES THIS EVENING...BUT THEN RAMP BACK UP
AGAIN LATE TONIGHT AND FRIDAY WITH COLD ADVECTION FOLLOWING THE
DEPARTING SFC LOW PRESSURE. WINDS WILL GUST AS HIGH AS
50KTS...RESULTING IN STORM FORCE WINDS FOR THE NW LOWER NEARSHORES.
SOLID GALES ALL OTHER MARINE AREAS. GRADIENT GRADUALLY LOOSENS UP
OVER THE WEEKEND...BUT GALES AND OBVIOUSLY CHOPPY WAVES WILL PERSIST
THROUGH FRIDAY NIGHT.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ008-
015>029-031>034.
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ030-
035-041.
LH...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LHZ345>349.
LM...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LMZ341.
STORM WARNING UNTIL 7 PM EST THIS EVENING FOR LMZ323-342-344>346.
LS...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LSZ321-322.
&&
$$
UPDATE...SD
SYNOPSIS...TL
SHORT TERM...AS
LONG TERM...BA
AVIATION...JA
MARINE...AS
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1158 PM EST THU DEC 20 2012
.SYNOPSIS...
ISSUED AT 414 PM EST THU DEC 20 2012
STRONG LOW PRESSURE OVER THE SOUTHERN GREAT LAKES...WILL CONTINUE TO
LIFT INTO SOUTHERN MICHIGAN...GENERATING CONTINUED WINTRY WEATHER
ACROSS NORTHERN MICHIGAN THROUGH FRIDAY. PERIODS OF HEAVY SNOW IS
EXPECTED FOR AREAS OF NORTHERN MICHIGAN THROUGH FRIDAY AFTERNOON.
ANY PRECIPITATION FALLING AS RAIN OR A RAIN....SNOW MIX WILL CHANGE
OVER TO SNOW THIS EVENING. WINDS WILL INCREASE TONIGHT AND CONTINUE
THROUGH FRIDAY.
&&
.UPDATE...
ISSUED AT 1053 PM EST THU DEC 20 2012
WOW...VERY IMPRESSIVE STORM UNFOLDING ACROSS THE REGION WITH
SURFACE LOW NEAR GLADWIN ATTM AND SLOWLY LIFTING NORTHEAST. OVER
THE LAST HOUR...HAVE NUMEROUS REPORTS OF THUNDER...3 INCHES OF
SNOW IN ONE HOUR AT PETOSKEY...AND EXPANDING POWER OUTAGES ACROSS
NORTHERN LOWER...NOT SURPRISING GIVEN THE HEAVY NATURE OF THE SNOW
ALONG WITH NUMEROUS REPORTS OF BRANCHES/TREES DOWN. EXPECT THAT WE
HAVE ANOTHER 2-4 HOURS BEFORE RATES BEGIN TO COME DOWN...WHICH
WILL LIKELY BRING TOTALS ABOVE 15" IN A FEW SPOTS /ESP OTSEGO
COUNTY/. RAIN/SNOW LINE IS STEADILY ADVANCING EAST /NOW SNOWING AT
PZQ/..AND WILL CONTINUE TO DO SO AS THE LOW PROGRESSES EAST.
LITTLE CHANGES NECESSARY TO THE GOING FORECAST...WITH SOME UPPED
SNOW TOTALS BASED ON EVENING OBSERVATIONS. WINDS WILL GET GOING
AFTER MIDNIGHT AS WELL...UNFORTUNATELY EXACERBATING AN ALREADY
HAZARDOUS SITUATION. IF YOU MUST BE OUT...USE EXTREME CAUTION!
UPDATE ISSUED AT 834 PM EST THU DEC 20 2012
LOOKING OUT THE WINDOW HERE AT APX REVEALS MODERATE TO HEAVY
SNOW...WITH RIMED DENDRITES SUGGESTING FAIRLY "WET" SNOW TO
LIQUID RATIOS /7-10:1/...IN AGREEMENT WITH EVENING OBSERVATIONS.
NOT SURPRISINGLY...CURRENT LIGHTNING DATA SHOWS SOME IN CLOUD
FLASHES OVER AND NEAR LITTLE TRAVERSE BAY...WITH A FEW REPORTS OF
THUNDER RECEIVED AT THE OFFICE. VERY HEAVY SNOW HAS NOW DEVELOPED
ALONG A FKS-CVX-MCD LINE WITH 1 INCH+/HOUR RATES PER SPOTTERS. AT
THE SAME TIME...HEAVY SNOWS CONTINUE OVER MUCH OF INTERIOR
NORTHERN LOWER...AND EASTERN UPPER /ESP ALONG I-75 PER SPOTTERS/.
GIVEN THIS EVOLUTION...WILL LEAVE GOING HEADLINES IN PLACE AS OF
THIS TIME. PRIMARY AREA OF CONCERN /OF LESS THAN WARNING LEVEL
SNOWS OVERNIGHT/ IS FROM TVC TO MBL...WHERE A GAP IN THE ECHOES
HAVE DEVELOPED WITH THE BETTER SOUTH-NORTH MOISTURE FEED FURTHER
EAST. STILL EXPECT...HOWEVER...THAT AS WE START TO GET THE LAKE
INVOLVED LATER TONIGHT THAT THIS WILL FILL BACK IN WITH
SIGNIFICANT ACCUMS. WITH WINDS KICKING UP HERE AFTER
MIDNIGHT...EXPECT A VERY HAZARDOUS MORNING COMMUTE...AND THUS THE
WARNING WILL REMAIN.
LOW PRESSURE LOOKS TO HAVE REACHED PEAK INTENSITY WITH OBS OVER
SOUTHWEST LOWER MICHIGAN SHOWING 985MB...HAVING COME UP 1-2 MB IN
THE LAST FEW HOURS. THUS...AS THE OCCLUSION PROCESS GETS
GOING...EXPECT OUR TRANSITION TO A COOLER AIRMASS TO GO AS
EXPECTED...WITH SNOWS COLLAPSING TO THE COAST OF NORTHEAST LOWER
AFTER MIDNIGHT.
UPDATE ISSUED AT 704 PM EST THU DEC 20 2012
TERRIFIC WV SATELLITE PRESENTATION OF OUR WINTER STORM AS H5 LOW
CROSSES THROUGH NORTHERN INDIANA WITH 984 MB LOW EMERGING OVER
SOUTHWEST LOWER MICHIGAN. CLASSIC TRACK TO KEEP NEARLY ALL OF OUR
CWA IN THE DEFORMATION PRECIPITATION THROUGH THE OVERNIGHT. RECENT
TRENDS IN THE DUAL POL PRODUCTS SUGGESTS A TRANSITION BACK TO SNOW IS
COMPLETE FROM MBL TO TVC...WITH VSBY RESTRICTIONS BECOMING GREATER
AT THESE SITES AS THE SNOWFALL INTENSITY INCREASES. A RAIN/SNOW
MIX...OR JUST PLAIN RAIN CONTINUES FROM CAD TO HTL TO APN WITH
ROGERS CITY SHIFTING TO RAIN LAST HOUR. THIS LINES UP FAIRLY WELL
WITH RECENT RAP TRENDS...WITH NEW APX RAOB SHOWING THE RAP IS
ABOUT 1C TOO WARM THROUGH THE LLEVELS. THUS...HAVE ONLY NEEDED
SOME MINOR TWEAKS TO THE WEATHER GRIDS FOR THE NEXT FEW HOURS.
PRECIPITATION RATES LOOK TO REMAIN IMPRESSIVE WITH CONVECTIVE
ELEMENTS CONTINUING TO FEED THE DEFORMATION BAND.
THEREFORE...OCCASIONAL 1-2"/HOUR SNOWFALL RATES LOOK PLAUSIBLE
THROUGH AT LEAST 06Z...AND THUS OVERNIGHT SNOWFALL AMOUNTS OF 6"+
FOR FAR NORTHERN LOWER AND EASTERN UPPER STILL LOOK GOOD. A
TERRIBLE TRAVEL NIGHT FOR SURE...WITH SOME POWER OUTAGES REPORTED
/AND LIKELY TO CONTINUE AND PERHAPS EXPAND AS WINDS GET GOING
AFTER MIDNIGHT/.
UPDATE ISSUED AT 556 PM EST THU DEC 20 2012
LOW PRESSURE CROSSING SOUTHERN LAKE MICHIGAN AT THIS HOUR...NEAR
983 MB /STILL A LITTLE BELOW NEAR TERM RUC GUIDANCE/. RAIN-SNOW
LINE HAS BEEN FLIRTING WITH THE TVC-GOV-APN CORRIDOR AND THIS IS
IN GOOD AGREEMENT WITH H8 WETBULB ZERO LINE. EXPECT THAT THIS WILL
SHIFT A LITTLE FURTHER NORTH AND EAST THIS EVENING UNTIL THE LOW
REACHES OUR LONGITUDE AROUND 9-10PM...IN LINE WITH RAP
EXPECTATIONS.
PRIMARY CHANGES INCLUDE REMOVING BLOWING SNOW MENTION THROUGH THE
EVENING UNTIL WE CAN GET THE NNW WINDS TO STRENGTHEN IN
COMBINATION WITH SLOWLY COOLING BL TEMPS. HAVE ALSO ADJUSTED
WEATHER GRIDS TO ACCOUNT FOR EXPECTED MOVEMENT OF THE RAIN/SNOW
LINE. FINALLY...HAVE ADJUSTED OVERNIGHT PRECIPITATION TOTALS PER
LATEST HRRR/RAP...BUT THIS ONLY RESULTS IN A MINOR CHANGE TO
PREVIOUS GRIDDED FORECAST. STILL EXPECT SOME SPOTS OVER INTERIOR
NORTHERN LOWER AND EASTERN UPPER TO SEE UPWARDS OF 6 ADDITIONAL
INCHES OVERNIGHT. WHILE A LITTLE LESS WILL FALL AT THE COASTS...IT
WILL BE FAR MORE THAN HAS BEEN SEEN THUS FAR...THEREFORE CAUSING
TRAVEL CONDITIONS IN THESE REGIONS TO DETERIORATE RAPIDLY.
HAVE ISSUED AN SPS TO HIGHLIGHT THE CHANGING EVENING CONDITIONS.
OTHERWISE...HEADLINES LOOK GOOD. WILL REASSESS OUR FAR SOUTHEAST
FOR POTENTIAL WINTER WEATHER ADVISORY NEEDED WELL AFTER MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
ON THE LATEST SURFACE WEATHER MAP OF INTEREST...984 MB LOW PRESSURE
WAS CENTERED NEAR CHICAGO ILLINOIS. APX AND SURROUNDING RADARS
SHOWED MODERATE TO HEAVY PRECIPITATION ACROSS MUCH OF NORTHERN
MICHIGAN. THE FORM OF WHICH IS ALL OVER THE MAP...SOME SPOTS ACROSS
THE HIGHER TERRAIN HAS HAD 6 INCHES OR MORE...WHILE THE LOWER
ELEVATIONS HAVE HAD 2 INCHES OR LESS (IN SOME CASES NEARLY NONE AT
ALL). FORECAST CHALLENGES ARE NUMEROUS WITH CHANGEOVER TO ALL SNOW
AND ADDITIONAL ACCUMULATIONS THE MAIN ONES.
TONIGHT...STORM SYSTEM WILL CONTINUE TO TRACK NORTHEAST ACROSS LOWER
MICHIGAN TONIGHT THEN INTO WESTERN NEW YORK FRIDAY. SNOWFALL RATES
ARE EXPECTED TO PICK UP ONCE AGAIN AND AS COLDER AIR GETS PULLED
INTO THE REGION FROM THE NORTH...SNOWFALL RATES ARE EXPECTED TO
INCREASE. WATER VAPOR LOOPS DEPICT A WELL-DEFINED BAROCLINIC LEAF
STRUCTURE. ACCOMPANYING STRONG DIVERGENCE WITHIN A COUPLED UPPER JET
STRUCTURE ATOP LOW/MID-LEVEL FRONTOGENESIS WILL SUPPORT AN INCREASE
IN SNOW RATES DURING THE NEXT FEW HOURS. DEEP ASCENT THROUGH
DENDRITIC GROWTH ZONES WITHIN THE 700-500-MB LAYER WILL SUPPORT
EFFICIENT SNOW GROWTH...WITH ISOTHERMAL PROFILES IN THE 850-700-MB
LAYER YIELDING EFFICIENT SNOW AGGREGATION. SNOWFALL RATES OF 1-1.5
INCHES WILL LIKELY BECOME COMMON LATER THIS EVENING...AS ONE OR MORE
NE/SW-ORIENTED SNOW BANDS DEVELOP WHILE THE SFC LOW APPROACHES. THE
ENHANCED SFC PRESSURE GRADIENT WILL SUPPORT NNE TO ENE WINDS OF
20-25 MPH WITH GUSTS REACHING 30 TO OCCASIONALLY 35 MPH. THIS WILL
SUPPORT REDUCED VISIBILITIES TO ONE-HALF MILE IN BLOWING SNOW...AND
LOCALIZED BLIZZARD CONDITIONS MAY OCCUR. ADDITIONAL ACCUMULATIONS
WILL VARY WIDELY FROM AN INCH OR LESS NEAR THE LAKE HURON LAKE
SHORES TO BETWEEN 4 AND 8 INCHES ACROSS EASTERN UPPER AND THE HIGHER
TERRAIN OF NORTHERN LOWER. LOWS RANGING FROM THE MIDDLE 20S NORTH TO
THE LOWER 30S SOUTHEAST.
FRIDAY...WRAP AROUND SNOW SHOWERS IN THE MORNING THEN DRIER
AIR/SUBSIDENCE/RIDGING BY LATE IN THE DAY WHICH SHOULD DIMINISH
ACTIVITY. THERE IS ALSO A BIT OF OVER LAKE INSTABILITY (DELTA TS OF
ABOUT 14) WITH STRONG NORTHERLY FLOW. THIS WILL LEAD TO WIDESPREAD
BLOWING AND DRIFTING SNOW...WITH ONLY ABOUT 2 INCHES OR LESS OF
ADDITIONAL ACTUAL ACCUMULATION. HIGHS IN THE UPPER 20S NORTH TO THE
MIDDLE 30S SOUTHEAST.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 414 PM EST THU DEC 20 2012
FOUR WAVE NRN HEMISPHERIC PATTERN IN PLACE TODAY WITH MAJOR TROUGH
AXES OVER FAR EASTERN ASIA AND ALONG THE NOAM WEST COAST. SW
FLOW/RIDGING AND RELATIVELY MILD TEMPERATURES EXISTS DOWNSTREAM
THROUGH THE PLAINS AND THE EASTERN CONUS...WITH MUCH OF NRN MICHIGAN
JUST COLD ENOUGH TO GET IN ON THE HEAVY SNOW WITH OUR ONGOING WINTER
STORM (ACTUALLY PARTS OF THE CWA IS WITHIN THE SWEET SPOT...THE
TRANSITION ZONE FROM RAIN TO SNOW WHERE YOU GET MAXIMUM MOISTURE
INFLOW). FLOW PATTERN REMAINS SOMEWHAT PROGRESSIVE ACROSS THE CONUS
THROUGH THE UPCOMING SEVEN DAY STRETCH BUT STILL ON THE OVERALL MILD
SIDE OF THE THINGS AS THE REALLY COLD AIR REMAINS STUCK ACROSS THE
POLE INTO EASTERN ASIA...A PATTERN THAT HAS DOMINATED THIS
FALL/EARLY WINTER SEASON SO FAR. BUT FIRST...HAVE TO GET THROUGH THE
ONGOING STORM.
FRIDAY NIGHT AND SATURDAY...ONGOING STRONG SYSTEM WILL BE EXITING
EAST OF THE STATE BY FRIDAY EVENING WITH MID LEVEL RIDING/SFC HIGH
PRESSURE AND DRIER AIR NOSING INTO THE WESTERN GREAT LAKES THROUGH
THE NIGHT. NNW FLOW LAKE SNOW SHOWERS AND GUSTY WINDS WILL PERSIST
THROUGH FRIDAY EVENING BEFORE DIMINISHING SUBSTANTIALLY OVERNIGHT
INTO THE DAY SATURDAY. ACCORDINGLY...WILL START OUT WITH CATEGORICAL
NNW FLOW LAKE SNOW SHOWERS FRIDAY EVENING BEFORE DIMINISHING/ENDING
BY SATURDAY MORNING. CURR
SATURDAY NIGHT THROUGH CHRISTMAS EVE...A RELATIVE LULL IN THE
WEATHER ACTION FOR THE LATTER HALF OF THE WEEKEND THROUGH CHRISTMAS
EVE WITH BROAD HIGH PRESSURE AND WEDGE OF DRIER AIR IN THE REGION.
THAT SAID...GUIDANCE DOES DEPICT A COUPLE WAVES WITHIN THE FAST NW
FLOW ALOFT SKITING THROUGH THE NRN PART OF THE STATE...ONE SATURDAY
NIGHT AND A STRONGER ONE ON SUNDAY. SOME COLDER AIR SAGGING BACK
INTO THE REGION BEHIND THE WAVE ENOUGH TO MAINTAIN AND/OR GENERATE
SOME LAKE SNOWS OFF THE GREAT LAKES...ESPECIALLY SUNDAY AS THE
STRONGER WAVE PASSES THROUGH. BUT OVERALL NOT A BIG DEAL WITH FAIRLY
DRY AIR IN CONTROL. SUNDAY NIGHT THROUGH CHRISTMAS EVE LOOKING QUIET
AT THIS POINT WITH BROAD HIGH PRESSURE THROUGH THE REGION.
CHRISTMAS DAY THROUGH THURSDAY (EXTENDED PERIODS)...SOLUTION
DIFFERENCES AMONG THE MEDIUM RANGE GUIDANCE...AS USUAL. GEM/GFS
SOLUTIONS ARE IN ONE CAMP KEEPING THINGS ON THE QUIET SIDE FOR
CHRISTMAS DAY (ALTHOUGH THE GFS DOES HAVE A WEAK FAST MOVING WAVE
MOVING THROUGH THE REGION). ECMWF HINTING AT ANOTHER STRONGER STORM
FOR TWO RUNS NOW PUSHING UP THROUGH THE OHIO VALLEY/GREAT LAKES ON
CHRISTMAS DAY. DIFFERENCES AMONG THE GUIDANCE ARE THE RESULT OF THE
DEGREE OF PHASING BETWEEN THE NRN AND SOUTHERN STREAMS WITH OBVIOUS
BIG IMPLICATIONS. NO WAY OF KNOWING THE CORRECT SOLUTION AT THIS
JUNCTURE...BUT WILL HAVE LOWER END SNOW CHANCES ON TUESDAY FOR NOW.
ANOTHER SHOT FOR A STORM SYSTEM MAY COME WEDNESDAY NIGHT THROUGH
THURSDAY WITH THE POTENTIAL FOR YET ANOTHER STORM TO SPIN UP OFF THE
GULF AND LIFT NORTHWARD THROUGH THE EASTERN CONUS. AGAIN...BIG
DIFFERENCES ON THE TIME/TRACK OF THAT STORM (IF IT OCCURS AT ALL).
BUT WILL CARRY CHANCE POPS FOR SNOW DURING THAT TIME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1151 PM EST THU DEC 20 2012
A COMBINATION OF IFR/MVFR CONDITIONS AT THE TAF SITES AT THE
MOMENT AS LOW PRESSURE NEAR TAWAS PUSHES EAST INTO LAKE HURON. ANY
MIX WITH RAIN IS NOW OVER AT APN...WITH SNOW THE ONLY PTYPE
THROUGH THE PERIOD. OCCASIONAL SNOWS WILL CONTINUE THROUGH
DAYBREAK WITH LIFR-IFR VSBYS/IFR CIGS POSSIBLE PARTICULARLY AT
PLN/TVC. RESTRICTIONS WILL GRADUALLY IMPROVE FOR THE DAY ON
FRIDAY...WITH MVFR CIGS/VSBYS IN LAKE EFFECT SHSN/BLOWING SNOW
WITH SOME LATE DAY/EVENING IMPROVEMENT TO VFR AT TVC/MBL.
WINDS HAVE SHIFTED NORTHERLY TO 10G20KTS ATTM AND WILL CONTINUE TO
BACK NORTHWESTERLY AND INCREASE TO 25G35KTS FOR THE DAY ON FRIDAY.
&&
.MARINE...
ISSUED AT 414 PM EST THU DEC 20 2012
MAJOR WINTER STORM LIFTING NE INTO THE GREAT LAKES THROUGH
TONIGHT...BEFORE DEPARTING FRIDAY. OVERLAKE INSTABILITY WITH
EASTERLY WINDS AT 20-35KTS TO DEVELOP AS MODERATE TO HEAVY SNOWS
(MIXED WITH OR ALL RAIN ACROSS LAKE HURON). THE SNOWS WILL BE
INCREASINGLY INTENSE THIS EVENING. WINDS WILL DECREASE SOME ACROSS A
GOOD CHUNK OF THE NEARSHORES THIS EVENING...BUT THEN RAMP BACK UP
AGAIN LATE TONIGHT AND FRIDAY WITH COLD ADVECTION FOLLOWING THE
DEPARTING SFC LOW PRESSURE. WINDS WILL GUST AS HIGH AS
50KTS...RESULTING IN STORM FORCE WINDS FOR THE NW LOWER NEARSHORES.
SOLID GALES ALL OTHER MARINE AREAS. GRADIENT GRADUALLY LOOSENS UP
OVER THE WEEKEND...BUT GALES AND OBVIOUSLY CHOPPY WAVES WILL PERSIST
THROUGH FRIDAY NIGHT.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 7 PM EST FRIDAY FOR MIZ008-015>029-
031>034.
WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ030-035-041.
LH...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LHZ345>349.
LM...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LMZ341.
STORM WARNING UNTIL 7 PM EST FRIDAY FOR LMZ323-342-344>346.
LS...GALE WARNING UNTIL 7 AM EST SATURDAY FOR LSZ321-322.
&&
$$
UPDATE...ARNOTT
SYNOPSIS...TL
SHORT TERM...AS
LONG TERM...BA
AVIATION...JA
MARINE...AS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1035 PM CST THU DEC 20 2012
.AVIATION... /06Z TAF ISSUANCE/
AREAS OF LOW END MVFR TO IFR CEILINGS REMAIN OVER THE AREA THIS
EVENING. FARTHER TO THE NORTHWEST AREA OF LOW LEVEL MOISTURE
REMAINS TRAPPED UNDER SUBSIDENCE INVERSION LOCATED BENEATH THE
SURFACE RIDGE OVER THE EASTERN DAKOTAS. SOME EXPANSION TO THE
SOUTH NOTED WITH THIS AREA. FURTHER WEST...SOME ICE FOG DEVELOPING
OVER EASTERN SOUTH DAKOTA. NEW NAM AND LATEST HRRR SHOWING SOME
POSSIBILITY OF LOWER CLOUDS AND ICE FOG DEVELOPING UNDER THE
RIDGE...BUT APPEARS BEST CHANCE WILL REMAIN OVER THE EASTERN
DAKOTAS. THE IFR CEILINGS AT KRWF REMAIN ASSOCIATED WITH ELEVATED
SNOW LAYER ALONG THE MN RIVER VALLEY DUE TO EARLIER BLSN. THIS WILL
GRADUALLY DISSIPATE AFTER 06Z AS WIND SUBSIDES. WILL HAVE TO HOLD
ONTO THE POSSIBILITY OF SOME LOW END MVFR CEILING FARTHER EAST INTO
WISCONSIN IN THE WAKE OF THE STORM...AS NARRE-TL INDICATED SOME HIGH
PROBABILITIES FOR THIS OCCURRING. SHOULD SEE SKC/VFR DEVELOPING INTO THE
MORNING FRIDAY...LASTING THROUGH FRIDAY NIGHT.
GUSTY NORTHWEST WINDS WILL DIMINISH OVER THE EASTERN AREAS LATER
TONIGHT/FRIDAY MORNING AND SURFACE WINDS WILL EVENTUALLY TURN
SOUTHERLY LATE FRIDAY AFTERNOON OVER THE WEST AS THE HIGH PRESSURE
RIDGE MOVES THROUGH.
KMSP...CONFIDENCE NOT HIGH ON VFR CONDITIONS REMAINING THROUGH THE
NIGHT. STILL SEE SOME BKN-OVC010-015 NORTHWEST OF THE AREA AND STILL
MAY WORK TO THE SOUTHEAST THROUGH THE EARLY MORNING. WILL HOLD ONTO
SOME FEW-SCT013 OVERNIGHT ANYWAY. SHOULD SEE VFR THEN DEVELOPING
FRIDAY MORNING LASTING FRIDAY NIGHT AS THE HIGH MOVES THROUGH.
NORTHWEST WINDS DIMINISHING OVERNIGHT AND THEN BECOMING MORE
SOUTHWEST LATE AFTERNOON AND SOUTHERLY AFTER 00Z SAT.
/OUTLOOK FOR KMSP/
FRI...VFR. NW 5 TO 10 KNOTS.
SAT...VFR. S 5 KNOTS.
SUN...VFR. NE 5 KNOTS.
&&
.DISCUSSION... /ISSUED 214 PM CST THU DEC 20 2012/
THE TOP WEATHER CONCERNS THIS FORECAST PERIOD ARE LOW TEMPERATURES
TONIGHT AND SNOWFALL CHANCES FOR CHRISTMAS EVE DAY.
LIGHT SNOW OVER WEST CENTRAL WISCONSIN WILL CONTINUE TO TAPER OFF
DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. WIND SPEEDS WILL
ALSO BE ON THE DOWNWARD TREND AND AREAS OF BLOWING SNOW WILL
GRADUALLY SUBSIDE ACCORDINGLY. WHILE MODELS MIGHT BE A BIT
OPTIMISTIC ON THE CLEARING TONIGHT GIVEN THE CYCLONIC FLOW AND
COLD AIR ADVECTION...THINK MOST OF THE CWA SHOULD SEE CLEAR SKIES
BY 06Z-09Z. HAVE LEANED TOWARD THE COLDER END OF NUMERICAL
GUIDANCE OVER THE NORTHWEST...WHERE LOWS SHOULD SNEAK INTO THE
SINGLE DIGITS BELOW ZERO GIVEN THE LONGER PERIOD OF CLEAR SKIES.
EAST AND SOUTH CENTRAL MN SHOULD SEE LOWS IN THE SINGLE DIGITS
ABOVE ZERO...WITH READINGS AROUND OR JUST ABOVE 10 DEGREES FROM
EAU CLAIRE TOWARD LADYSMITH WHERE CLOUDS ARE EXPECTED TO LINGER
LONGER.
A RATHER BENIGN WEATHER PATTERN SETS IN FOR FRIDAY THROUGH THE
WEEKEND...AS WEAK RIDGING DOMINATES. DRY WEATHER AND BELOW NORMAL
HIGH TEMPERATURES WILL PREVAIL.
BY SUNDAY NIGHT...THE LARGE SCALE REGIME WILL TRANSITION TO THAT
OF A MORE ZONAL NATURE...AND MODELS HAVE BEEN FAIRLY CONSISTENT IN
DROPPING A NORTHERN STREAM SHORTWAVE ACROSS THE AREA ON THE 24TH
INTO THE 25TH. LOOKS LIKE THE WAVE COULD PRODUCE A QUICK INCH OF
SNOW ACROSS MUCH OF THE FORECAST AREA.
COOL CANADIAN HIGH PRESSURE SETTLES IN TO THE NORTH CENTRAL CONUS
FROM CHRISTMAS THROUGH MOST OF NEXT WEEK. HIGH TEMPERATURES WILL
AVERAGE BETWEEN 5 AND 15 DEGREES BELOW NORMAL...WHICH TRANSLATES
TO HIGHS FROM THE SINGLE DIGITS /WEST/ TO AROUND 20 ABOVE /EAST/.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
LS/DWE
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
1236 AM EST FRI DEC 21 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL MOVE OFFSHORE BY EARLY FRIDAY MORNING.
HIGH PRESSURE WILL SLOWLY BUILD INTO THE AREA FROM THE SOUTHWEST
FRIDAY THROUGH SUNDAY. A WARM FRONT WILL MOVE INTO THE AREA MONDAY
AND BECOME STATIONARY THROUGH WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 1230 AM FRIDAY...STRONG COLD FRONT NOW MOVING INTO THE MHX
CWA ALTHOUGH AXIS OF LOWER DEWPOINTS STILL ABOUT 50 MILES OR SO
BEHIND THE ACTUAL FRONT. THE SURFACE LOW IS RAPIDLY DEEPENING WITH
3 HOURLY PRESSURE FALLS OF CLOSE TO 10 MB OVER CENTRAL VIRGINIA.
STRONG GUSTY WINDS WILL ACCOMPANY THE FRONTAL PASSAGE WITH
OBSERVATIONS AND WIND PROFILE DATA SHOWING THE POTENTIAL FOR GUSTS
TO AROUND 45 KNOTS. CONVECTIVE PARAMETERS SHOW THE BEST SEVERE
POTENTIAL REMAINING OFFSHORE...BUT SOME HEAVIER SHOWERS WILL
CERTAINLY MIX DOWN GUSTY WINDS OVER THE NEXT 3 TO 5 HOURS OR SO.
TEMPERATURES WILL HOLD STEADY FOR NEXT 3 OR 4 HOURS BEFORE FALLING
WITH THE ARRIVAL OF THE DEWPOINT FRONT. THE LATEST RAP IS A BIT
FASTER MOVING MOST OF THE PRECIPITATION OFFSHORE BETWEEN 10Z AND
12Z.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 AM SATURDAY/...
AS OF 400 PM THURSDAY...STRONG CAA IN WAKE OF FRONT ALONG WITH GOOD
MOMENTUM TRANSPORT WITH SHRT WV MOVING ACROSS WILL PRODUCE STRONG
WESTERLY WINDS...WITH GUSTS TO 40 MPH PSBL INLAND AND POSSIBLY UP TO
45 MPH COAST. THIS IS JUST BELOW WIND ADVSY CRITERIA AND PER COORD
WITH SURROUNDING OFFICES HAVE ISSUED SPS AND WILL LET OVERNIGHT
SHIFT LOOK AT NEXT MODEL RUN. SOME COLD AIR SCU LIKELY DURING AFTN
SPREADING IN FROM NW. MOS BLEND SUPPORTS PREVIOUS FCST MAX TEMPS IN
LOW-MID 50S.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
AS OF 330 PM THURSDAY...COLD FRONT WILL BE WELL OFFSHORE FRIDAY
NIGHT...BUT STILL REMAIN A TIGHT SURFACE PRESSURE GRADIENT. MODELS
CONTINUE TO BE A GOOD AGREEMENT FOR THIS WEEKEND WITH A TIGHT
SURFACE PRESSURE GRADIENT TO REMAIN UNTIL SATURDAY. HIGH PRESSURE
WILL SLOWLY BUILD IN OVER THE WEEKEND...WITH WEAK FRONT TO MOVE
THROUGH MONDAY THIS FRONT WILL BECOME STATIONARY OVER NC...BRING AN
INCREASE OF MOISTURE TO THE AREA. THE STATIONARY FRONT WILL LIFT
NORTH AS AN APPROACHING LOW PRESSURE SYS MOVES TO OUR WEST OF
EASTERN NC BRINGING ITS ASSOCIATED COLD FRONT ACROSS NC APROX
THURSDAY. BOTH THE GFS AND ECMWF DO NOT HAVE A GOOD HANDLE OF THIS
NEXT SYSTEM...SO HAVE GONE WITH HPC GUIDANCE.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
SHORT TERM /THROUGH FRIDAY/...
AS OF 1230 AM FRIDAY...SOME MVFR CEILINGS WITH A FEW PERIODS OF
IFR ARE LIKELY THROUGH ABOUT 08Z OR 09Z AS FRONTAL BOUNDARY
ADVANCES QUICKLY ACROSS THE REGION. PRECIPITATION SHOULD EXIT THE
COAST BY 12Z BUT GUSTY W/WNW WILL CONTINUE BEHIND THE FRONT INTO
THE EVENING HOURS. WITH STEEP LAPSE RATES...WOULD EXPECT SOME
BROKEN STRATOCUMULUS TO DEVELOP DURING THE AFTERNOON...ALTHOUGH
MODEL SOUNDINGS KEEP CEILINGS ABOVE 3000 FT AND IN THE VFR RANGE.
.
LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 330 PM THURSDAY...EXPECT VFR CONDITIONS TO CONTINUE THROUGHOUT
THE WEEKEND WITH BREEZY CONDITIONS THROUGH SATURDAY AS HIGH PRESSURE
BUILDS IN FROM THE SOUTH.
&&
.MARINE...
SHORT TERM /THROUGH FRIDAY/...
AS OF 1235 AM FRIDAY...GALE CONDITIONS OCCURRING OVER THE SOUTHERN
WATERS WITH GUSTS TO 39 KNOTS AT CAPE LOOKOUT AND 41 KNOTS AT THE
BUOY 30 MILES SOUTHEAST OF NEW RIVER INLET. EXPECT ADDITIONAL GALE
FORCE WINDS TO OCCUR AS STRONG SURFACE FRONT EDGES ACROSS THE CWA
EARLY THIS MORNING. SEAS ALREADY IN THE 6 TO 10 FOOT RANGE AT THIS
TIME. NO MAJOR CHANGES NEEDED TO CURRENT MARINE FORECAST.
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 330 PM THURSDAY...COLD FRONT WILL BE WELL OFFSHORE...BUT
STILL REMAINS A TIGHT SURFACE PRESSURE GRADIENT BEHIND THE FRONT.
WINDS WILL REMAIN FROM THE WEST IN GALE FORCE UNTIL SATURDAY
AFTERNOON. WINDS WILL CONTINUE TO SUBSIDE SATURDAY AFTERNOON AS
HIGH PRESSURE BUILDS IN FROM THE SOUTH. EXPECT...SEAS TO CONTINUE
TO SUBSIDE FRIDAY NIGHT THROUGH SATURDAY.
&&
.TIDES/COASTAL FLOODING...
AS OF 300 PM THURSDAY...GUSTY WESTERLY WINDS 25 TO 35 MPH WILL
DEVELOP FRIDAY AND PERSIST INTO SATURDAY...WITH EXTRATROPICAL STORM
SURGE GDNC INDICATING WATER LEVEL RISES OF 1 TO 2 FEET SOUNDSIDE OF
OUTER BANKS. COASTAL FLOOD ADVISORY ISSUED ACCORDINGLY.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...WIND ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR NCZ095-103-
104.
COASTAL FLOOD ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST
SATURDAY FOR NCZ103-104.
MARINE...GALE WARNING UNTIL 1 PM EST SATURDAY FOR AMZ130-135-150-152-
154-156-158.
&&
$$
SYNOPSIS...JBM
NEAR TERM...CTC
SHORT TERM...JBM/BM
LONG TERM...BM
AVIATION...CTC/BM
MARINE...CTC/BM
TIDES/COASTAL FLOODING...JBM
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
338 AM CST FRI DEC 21 2012
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
CHALLENGE WILL BE CLOUD COVER AND TEMPERATURES TODAY AND THEN
PRECIPITATION CHANCES SUNDAY NIGHT. MODELS ARE IN GOOD AGREEMENT...
BUT WILL FOCUS ON 925 HPA RH OUTPUT FROM THE HIGH RESOLUTION RAP
FOR NEAR TERM CLOUD TRENDS.
09 UTC SATELLITE LOOP SHOWS A WEDGE OF LOW STRATUS ENCOMPASSING
ALL OF THE FORECAST AREA EXCEPT FOR EXTREME SOUTHEAST ND INTO
ADJACENT PORTIONS OF WEST CENTRAL MN. THIS AREA OF CLOUDS IS
SAGGING TO THE SOUTH AROUND 10 KTS WITH VERY LITTLE EAST-WEST
MOVEMENT. RAP SUGGESTS CLOUDS WILL MOVE VERY SLOWLY TO THE EAST
THROUGH THE DAY AS SOUTHERLY RETURN FLOW DEVELOPS ON BACKSIDE OF
DEPARTING SURFACE RIDGE. MIXING WITHIN THE RIDGE ITSELF IS ALMOST
NON-EXISTENT...SO SEE NO REASON WHY CLOUDS WOULD BREAK-UP EARLY.
FOR THIS...INCREASED SKY COVER THROUGH THE DAY ALONG AND EAST OF
THE VALLEY. THINK THERE SHOULD BE SOME CLEARING ALONG THE VALLEY
BY THIS AFTERNOON...BUT NOT UNTIL AFTER SUNSET ACROSS MUCH OF
NORTHWEST MN. DESPITE MODEST LOW-MID LEVEL WARM AIR ADVECTION...
DO NOT EXPECT MUCH TEMPERATURE RECOVERY UNDER CLOUDS..SO DECREASED
AFTERNOON HIGHS INTO THE LOW TO MID TEENS MOST LOCATIONS. SOME
SCATTERED FLURRIES ARE POSSIBLE THROUGH THE DAY...BUT NO REAL
ACCUMULATION IS EXPECTED. ALSO COULD SEE SOME PATCHY FOG EARLY
THIS MORNING ALONG THE WESTERN FLANK OF THE STRATUS DECK.
A DRY COLD FRONT WILL DROP SOUTH FROM CANADA TONIGHT AND SATURDAY.
DO NOT EXPECT ANY SNOW...BUT WINDS WILL SHIFT TO THE NORTHWEST
WITH A REINFORCING SHOT OF LOW CLOUDS. AFTERNOON HIGHS ON SATURDAY
WILL RANGE FROM 10 ABOVE ACROSS THE DEVILS LAKE BASIN TO NEAR 20
DEGREES ACROSS LAKES COUNTRY OF WEST CENTRAL MN. ANOTHER COOL...
BUT DRY DAY ON SUNDAY WITH LIGHT NORTHERLY WIND. HIGHS ACROSS
EASTERN ND INTO PORTIONS OF NORTHWEST MN NOT LIKELY TO BREAK OUT
OF THE SINGLE DIGITS.
ATTENTION TURNS TO SUNDAY NIGHT AS 700 HPA LOW MOVES INTO THE
CENTRAL VALLEY. MID-LEVEL FRONTOGENESIS AND UPPER LEVEL DYNAMIC
SUPPORT IS LACKING...BUT CONVERGENCE ALONG THE TRACK OF THE MID-
LEVEL CIRCULATION COMBINED WITH SOME WARM AIR ADVECTION INDUCED
LIFT SHOULD RESULT IN SOME LIGHT SNOW MAINLY ALONG AND NORTH OF
THE HIGHWAY TWO CORRIDOR. INCREASED POPS INTO THE 30 TO 40 PERCENT
RANGE...BUT ACCUMULATIONS SHOULD BE LIGHT...GENERALLY 1-2 INCHES
OR LESS.
.LONG TERM...MONDAY THROUGH THURSDAY NIGHT
THE PATTERN WILL BEGIN WITH MAINLY ZONAL FLOW AND A CHANCE FOR
SOME LIGHT SNOW CHRISTMAS EVE WITH A SHORTWAVE. THEREAFTER...SFC
RIDGING WILL BUILD SOUTH FROM CANADA...AND RESULT IN DRY WEATHER
TUE-THU AND TEMPS BELOW NORMAL. THERE ARE SOME INDICATIONS THAT
MORE OF AN ACTIVE SW FLOW ALOFT MAY DEVELOP THU NIGHT AND FRI...
AND THE POTENTIAL FOR SOME SORT OF STORM SYSTEM...SO SOMETHING TO
MONITOR.
&&
.AVIATION...
MVFR/IFR STRATUS DECK WILL MOVE VERY SLOWLY TO THE EAST THROUGH
THE DAY. IMPROVING CEILINGS NOT EXPECTED AT KFAR/KGFK UNTIL 18 UTC
OR LATER AND 21 UTC OR LATER AT KTVF/KBJI. SCATTERED FLURRIES ARE
POSSIBLE WITH CLOUD COVER WITH AN INFREQUENT REDUCTION IN
VISIBILITY TO 5 SM. LIGHT AND VARIABLE WIND WILL INCREASE FROM THE
SOUTH FROM WEST TO EAST AS SURFACE HIGH MOVES INTO EASTERN MN.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
ROGERS/DK
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1246 AM EST FRI DEC 21 2012
.SYNOPSIS...
STRONG COLD FRONT PLOWS THROUGH THIS EVENING. SNOW SHOWERS BEHIND
LOW PRESSURE TONIGHT INTO SATURDAY. HIGH PRESSURE PASSES SUNDAY. LOW
PRESSURE CHRISTMAS EVE AND AGAIN MIDWEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1230 AM UPDATE...
COLDER AIR A BIT SLOWER TO ARRIVE...BUT GRAUPEL WAS OCCURRING A
LITTLE BIT AGO AT THE OFFICE AND HTS JUST CHANGED OVER TO -SN AT
THE 05Z OB...SO THE TRANSITION FROM RAIN TO SNOW STILL GENERALLY
ON TRACK.
PREVIOUS DISCUSSION FOLLOWS...
INITIAL PRECIP FROM THIS MORNING HAS MOSTLY LIFTED TO THE
NORTH...WITH THE NEXT BATCH ALREADY WELL INTO WESTERN CWA. HAVE
GOTTEN SOME REPORTS OF LIGHT SNOW FALLING ACROSS HIGHER TERRAIN IN
NORTHERN WV MOUNTAINS. THIS IS TIED TO A SMALL COLD POOL STILL IN
PLACE...BUT AS WINDS SHIFT AROUND TO MORE S THEN SW...THIS COLD POOL
SHOULD BE CLEARED OUT WITH A RETURN TO RAIN UNTIL TONIGHT. ALL THIS
CURRENT PRECIP IS STILL WELL PRE-FRONTAL...WITH THE COLD FRONT
CURRENTLY RUNNING FROM THE LOW IN NORTHEASTERN IL...THROUGH SW
IN...AND CENTRAL KY/TN. AT 19Z...FRONT SHOWING UP WELL ON RADAR IN
KY...RUNNING FROM ROUGHLY KGLW TO KSDF. PRE-FRONTAL PRECIP SHOULD
WRAP UP BEFORE THE FRONT...WITH A THIN LINE OF SHOWERS RIGHT ALONG
THE FRONT. IN GENERAL PRE-FRONTAL WIND GUSTS HAVE BEEN 20-35
KTS...WITH THE STRONGER GUSTS BEHIND THE FRONT. CONSIDERED STARTING
WIND ADVISORY EARLIER...BUT NOT SEEING ANY OBS WITH CRITERIA OPTED
TO LEAVE AS IS...WAITING FOR THOSE STRONGER GUSTS BEHIND THE FRONT.
MODELS STILL SHOWING A PRETTY GOOD DRY SLOT BEHIND THE FRONT...SO
TRANSITION AN AREA OF LOW SLIGHT CHANCE POPS ACROSS THE CWA FROM
ABOUT 03Z TO 06Z...THEN HAVE WRAP AROUND MOISTURE SURGING BACK IN.
INITIALLY...COLD AIR WILL STILL BE LAGGING BEHIND THE FRONT OF THE
PRECIP SHIELD...SO WRAP AROUND SHOULD START AS RAIN SHOWERS. THEN AS
COLD AIR SURGES IN WILL SEE A TRANSITION FROM RAIN TO SNOW IN THE
MOUNTAINS AND ALSO MOVING ACROSS THE LOWLANDS FROM WEST TO EAST.
WITH THE WRAP AROUND...COORDINATED WITH SHORT TERM FORECASTER ON A
WINTER WEATHER ADVISORY STARTING AT 06Z FROM PERRY COUNTY OHIO EAST
TO THE ALREADY IN PLACE ADVISORY IN WV.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/...
SIGNIFICANT UPSLOPE SNOW EVENT IMPACTS THE AREA THIS PERIOD.
WRAP AROUND ARRIVES FROM THE W RIGHT AT THE START OF THE PERIOD.
MODELS INCLUDING NEAR TERM HIRES SUGGESTS THIS IMPACTS MID SE OHIO
BEFORE LIFTING THROUGH FAR NORTHERN WV AND ON INTO PA FRI. GENERAL
UPSLOPE FLOW ALSO SETS UP RIGHT AT THE START OF THE PERIOD AND
PERSISTS INTO SAT BEFORE WINDING DOWN SAT AFTERNOON AND EVENING.
AS COMMA / WRAP AROUND TAIL LIFTS OUT FRI...SECOND PLUME OFF LAKE
MICHIGAN MAY SET UP FOR A TIME...PERHAPS A LITTLE S OF WHERE THE
INITIAL WRAP AROUND OCCURS. IT THEN WILL EITHER DRIFT INTO THE SAME
AREA AFFECTED BY THE INITIAL RAP AROUND OR SIMPLY FADE IN PLACE LATE
FRI.
THE WESTERN SLOPES OF THE MOUNTAINS EXPERIENCE STRONG UPSLOPE
WINDS AS THE HIGH SPEEDS SOMEWHAT MAKE UP THE THE LESS THAN
PERPENDICULAR ANGLE PER W FLOW. AIR MASS IS COLD ENOUGH AND
MOISTURE DEPTH GREAT ENOUGH TO EASILY SUPPORT FAVORED DENDRITIC
GROWTH MOST OF THE TIME AND THUS SIGNIFICANT SNOW ACCUMULATIONS.
LEFT WARNINGS AND ADVISORIES AS IS EXCEPT TO EXPAND THE ADVISORY W
ACROSS OUR FAR NORTHERN WV COUNTIES AND ON BACK THROUGH MID SE OHIO
WHERE INITIAL WRAP AROUND SETS UP. SNOW AMOUNTS FARTHER S AND W ARE
ONLY A LITTLE LOWER THOUGH AND REMAINING COUNTIES NOT WARNED OR
ADVISED WILL STILL HAVE WINTRY IMPACTS.
ENTERTAINED BLIZZARD WARNINGS NORTHERN MOUNTAINS BUT RECKONED 3 HRS
OF 1/4SM SN BLSN WOULD BE HARD TO REALIZE SAVE MAYBE FOR THE HIGHEST
WINDWARD SLOPES. SIMILAR DEAL ON HIGH WIND WARNING AS ONLY A FEW
LOCATIONS WILL EXPERIENCE BRIEF GUSTS PAST 50 KTS. 60-65 KTS FLOW
SHOWN AT H85 FRI NT PER NOCTURNAL JET BUT THIS WILL NOT BE REALIZED
AT SURFACE...CLOSE ONLY ACROSS THE HIGHEST EXPOSED RIDGES.
MAINTAINED AREA WIDE WIND ADVISORY.
SNOWS AND WINDS WIND DOWN AND CLEARING COMMENCES SW TO NE SAT MIDDAY
THROUGH SAT NT AS HEIGHTS RISE AND WEAK LOW-MID LEVEL WARM ADVECTION
COMMENCES.
USED A HIRES/NAM/MOS COMBINATION ON TEMPERATURES THROUGH FRI NT
WHICH REFLECTS CORE OF THE COLD AIR CROSSING FRI MIDDAY AND
AFTERNOON. HAVE SUBFREEZING TEMPERATURES EVERYWHERE DURING THAT
TIME WHICH...TOGETHER WITH THE WINTER SOLSTICE...WILL FAVOR DAYTIME
ACCUMULATIONS. TEMPERATURES SAT AND SAT NT NEEDED NOTHING MORE THAN
MINOR EDITS IN LIGHT OF LATEST OF GUIDANCE / ON LOW SIDE / ...AS
SYSTEM SLOWLY PULLS OUT.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
THIS WILL BE A VERY UNSETTLED WEATHER PATTERN WITH CHANGEABLE
TEMPERATURES...IN WHICH TWO LOW PRESSURE SYSTEMS WILL AFFECT THE
AREA. THE MODELS ARE NOT IN GOOD AGREEMENT WITH THE STRENGTH AND
TIMING OF THESE SYSTEMS. RELYING MORE ON THE ENSEMBLES TO MITIGATE
THE DIFFERENCES WILL BE THE WAY TO GO...SO HPC GUIDANCE WITH THE
BLEND OF MODEL DATA WAS FOLLOWED CLOSELY.
EXPECT A DRY AND CHILLY DAY SUNDAY UNDER HIGH PRESSURE.
THE FIRST SYSTEM MONDAY AND MONDAY NIGHT WILL BE ON THE FLAT SIDE
WITH A WEAK LOW PRESSURE SYSTEM TRACKING ACROSS ALONG THE OHIO
RIVER. THIS WILL PUT US ON THE MILD SIDE WITH MAINLY RAIN
MONDAY...EXCEPT POSSIBLY SNOW IN THE NORTHERN
MOUNTAINS...TRANSITIONING TO SOME LIGHT SNOW ON THE BACK SIDE ACROSS
THE NORTH MONDAY NIGHT.
KEPT LOW LIQUID POPS SOUTH TUESDAY WITH FRONTAL SYSTEM TO OUR
SOUTH...BUT MOST OF THE AREA WILL BE DRY AND CHILLY WITH WEAK HIGH
PRESSURE.
SECOND SYSTEM LOOKS TO BE MUCH STRONGER AS IT TRACKS NORTHEASTWARD
TO THE WEST OF OUR AREA...BRINGING A GOOD SHOT OF MILD AIR AND
SIGNIFICANT RAIN WEDNESDAY. AS THE LOW PASSES WEDNESDAY
NIGHT...EXPECT A GENERAL TRANSITION TO SNOW WEDNESDAY NIGHT INTO
THURSDAY MORNING.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
EXPECT DEVELOPMENT OF WIDESPREAD MVFR CONDITIONS AND LOCAL IFR
CONDITIONS...WHICH WILL REMAIN FOR MUCH OF THE TAF PERIOD.
PERIODIC IFR CONDITIONS AND UNDER WILL OCCUR AT TIMES ON FRIDAY IN
HEAVIER SNOW SHOWERS.
IN ADDITION...VERY STRONG WINDS WILL DEVELOP BEHIND THE COLD
FRONT. EXPECT WIND GUSTS OF UP TO 40 KTS ACROSS THE
LOWLANDS...AND UP TO 50 KTS ACROSS THE HIGHER TERRAIN BEHIND THE
FRONTAL PASSAGE FOR MUCH OF THE VALID PERIOD.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING OF PRECIPITATION AND LOWER CLOUDS COULD
VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE FRI 12/21/12
UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12
CRW CONSISTENCY L L L M M M M M L L M M
HTS CONSISTENCY M L L L L M M L L L L L
BKW CONSISTENCY L L M M M M M M M M M M
EKN CONSISTENCY L M M M M M M M M M M M
PKB CONSISTENCY L L L M M M M L L L L L
CKB CONSISTENCY L L L M M M M M L L L M
AFTER 06Z SATURDAY...
IFR POSSIBLE INTO SATURDAY DUE TO SNOW SHOWERS...ESPECIALLY IN
THE MOUNTAINS. IFR CONDITIONS MAY LINGER ACROSS THE HIGHER TERRAIN
INTO SUNDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR WVZ005>011-
013>020-024>034-039-040.
WIND ADVISORY UNTIL 7 AM EST SATURDAY FOR WVZ035>038-046-047.
WINTER STORM WARNING UNTIL 2 PM EST SATURDAY FOR WVZ036>038-
046-047.
WINTER WEATHER ADVISORY UNTIL 2 PM EST SATURDAY FOR WVZ027-028-
035-039-040.
WINTER WEATHER ADVISORY UNTIL 7 AM EST SATURDAY FOR WVZ015-016-
018-025-026-029>034.
WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
WVZ008>011-017-019-020.
OH...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR OHZ066-067-075-
076-083>087.
WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
OHZ066-067-075-076-085.
KY...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR KYZ101>103-105.
VA...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR VAZ003-004.
&&
$$
SYNOPSIS...TRM/JMV/MZ
NEAR TERM...MZ/50
SHORT TERM...TRM
LONG TERM...JMV
AVIATION...50
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
240 AM CST FRI DEC 21 2012
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
240 AM CST FRI DEC 21 2012
MAIN FORECAST CONCERNS TO BEGIN THE FIRST DAY OF WINTER ARE ON
TEMPERATURES TONIGHT...ANY LOW CLOUD POTENTIAL SATURDAY NIGHT INTO
SUNDAY...AND ANY PRECIPITATION POTENTIAL SUNDAY NIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED DEEP TROUGHING OFF THE WEST COAST OF THE U.S....RIDGING
BUILDING ALONG THE LEE OF THE ROCKIES INTO SOUTH CENTRAL CANADA...
AND DEEP TROUGHING FROM THE GREAT LAKES INTO THE SOUTHEASTERN U.S..
THE LATTER DEEP TROUGHING CONTAINS THE STRONG STORM SYSTEM THAT
BROUGHT THE SNOW AND STRONG WINDS TO THE FORECAST AREA YESTERDAY.
ROADS STILL REMAIN HAZARDOUS TOO...ESPECIALLY OVER THE SOUTHEASTERN
PORTION OF THE FORECAST AREA. WINDS REMAIN BRISK...DUE TO A TIGHT
PRESSURE GRADIENT BETWEEN 987MB LOW PRESSURE NEAR DETROIT AND A
1025MB HIGH PRESSURE RIDGE OVER THE EASTERN DAKOTAS. WITH THE
FORECAST AREA EXPERIENCING RISING HEIGHTS AT 500MB...ABOUT 40 METERS
SINCE 00Z ACCORDING TO THE RAP...SUBSIDENCE HAS BEEN ON THE
INCREASE. DRY ADVECTION WAS ALSO OCCURRING...NOTED BY THE
PRECIPITABLE WATER DROPPING AT MPX FROM 0.33 INCHES AT 12Z ON THE
20TH TO 0.16 INCHES AT 00Z. THE COMBINATION OF SUBSIDENCE AND DRYING
HAS LED TO CLEARING SKIES IN THE WAKE OF THE STORM SYSTEM. CLEARING
LINE STRETCHED FROM EAU CLAIRE TO LA CROSSE AND DUBUQUE. COLDER AIR
ALSO ACCOMPANYING THE SUBSIDENCE AND DRYING...REFLECTED BY SURFACE
TEMPERATURES IN THE SINGLE DIGITS ACROSS WESTERN PORTIONS OF
MINNESOTA AND IOWA...AND IN THE SINGLE DIGITS BELOW ZERO OVER THE
EASTERN DAKOTAS UNDER THE SURFACE RIDGE. 925MB TEMPS AT MPX AT 00Z
WERE -10C...ABOUT 3 COLDER THAN 12 HOURS EARLIER.
TODAY AND TONIGHT...THE UPPER RIDGING ALONG THE LEE OF THE ROCKIES
WILL SHIFT EASTWARD INTO THE PLAINS BY TONIGHT IN RESPONSE TO THE
DEEP EAST PACIFIC TROUGH APPROACHING THE WESTERN U.S. COAST. WITH
THE UPPER RIDGING TRYING TO PUSH INTO THE FORECAST AREA...MID LEVEL
HEIGHTS WILL CONTINUE TO CLIMB...MAINTAINING THE SUBSIDENCE. IN
ADDITION...THE SHIFT EAST IN THE UPPER PATTERN OCCURS AT THE SURFACE
AS WELL...WITH THE HIGH PRESSURE RIDGE SHIFTING EAST OVER THE
FORECAST AREA AROUND MIDNIGHT. WITH THE SUBSIDENCE AND DRYING
PATTERN IN PLACE...EXPECT A DRY PERIOD. IN FACT...OTHER THAN A FEW
HIGH CLOUDS AFTER MIDNIGHT TONIGHT CROSSING THE UPPER RIDGE...SKIES
SHOULD BE MAINLY CLEAR. DESPITE THE PLENTIFUL SUNSHINE TODAY...
BREEZY NORTHWEST WINDS COMBINED WITH 925MB TEMPS IN THE -6 TO -10C
RANGE AND FRESH SNOW COVER WILL LIMIT HEATING. HIGHS SHOULD TOP OUT
FROM THE MID TEENS TO MID 20S...COLDEST OVER THE HIGHER ALBEDO
PRESENT WEST OF THE MISSISSIPPI RIVER. CONCERN FOR TEMPERATURES
PLUMMETING TONIGHT GIVEN THE COOLER DAY TODAY...DECOUPLING WINDS AND
MOSTLY CLEAR SKIES. HAVE LEANED TOWARDS THE COLD SIDE OF GUIDANCE AS
A RESULT.
SATURDAY AND SATURDAY NIGHT...MODELS ARE POINTING TO A SHORTWAVE
CURRENTLY IN SOUTHEAST BRITISH COLUMBIA TOPPING THE RIDGE AND MOVING
THROUGH EASTERN LAKE SUPERIOR SATURDAY NIGHT. ALTHOUGH THIS
SHORTWAVE IS FAR FROM US...A COLD FRONT ACCOMPANIES THE SHORTWAVE
WHICH SLIDES THROUGH THE FORECAST AREA SATURDAY NIGHT. AHEAD OF THE
FRONT...WE SEE SOME 925MB WARMING...PROGGED TO CLIMB TO -2C OR SO
BY 18Z SATURDAY. 850MB TEMPS ARE EVEN WARMER...0-3C OR SO...BUT
THERE IS NO WAY OF MIXING UP TO THIS DUE TO BEING NOW AT THE
SHORTEST DAY LENGTH AND HAVING THE FRESH SNOW. NEVERTHELESS...
COMBINATION OF SUN THROUGH SOME HIGH CLOUDS AND SOUTHWEST WINDS
PICKING UP A BIT SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE 20S
EVERYWHERE. SOME VALLEY LOCATIONS COULD PUSH 30. NOT ANTICIPATING
ANY PRECIPITATION TO ACCOMPANY THE FRONTAL PASSAGE...DUE TO
PLENTIFUL DRY AIR AND ALL FORCING WELL NORTHEAST OF THE AREA.
HOWEVER...AFTER THE FRONTAL PASSAGE...CONCERNED THERE MAY BE AN
INCREASE OF LOW CLOUDS AS SUGGESTED BY 21.00Z GFS 925MB RH FIELDS.
THE 21.00Z NAM AND ECMWF 925MB RH FIELD ARE NOT NEARLY AS
PESSIMISTIC AND THUS WILL CONTINUE WITH THE PREVIOUS MOSTLY CLEAR
FORECAST. COMBINATION OF COLD ADVECTION IN THE WAKE OF THE FRONT AND
RADIATIONAL COOLING ARE EXPECTED TO SEND TEMPERATURES BACK DOWN INTO
THE SINGLE DIGITS AND TEENS.
SUNDAY AND SUNDAY NIGHT...SOME OF THE CURRENT EASTERN PACIFIC TROUGH
IS PROGGED BY ALL MODELS TO HEAD EAST INTO THE PLAINS SUNDAY NIGHT.
ASSOCIATED WITH THIS UPPER TROUGHING IS A NORTHWEST TO SOUTHEAST
ORIENTED INVERTED TROUGH AT THE SURFACE...WHICH BY 12Z MONDAY SHOULD
HAVE REACHED AT LEAST SIOUX FALLS PER MODEL CONSENSUS. GIVEN THE
APPROACH OF THE UPPER AND INVERTED SURFACE TROUGH...ONE WOULD EXPECT
AN ISENTROPIC LIFT PATTERN...WHICH INDEED EXISTS. HOWEVER...ANY
ISENTROPIC LIFT IS ROOTED ON THE 290-300K SURFACES WHICH PUTS IT AT
A PRESSURE LEVEL OF 700MB OR HIGHER...AND MORE TOWARDS 12Z.
THEREFORE...NOT SURE IF ANY PRECIPITATION CAN MAKE IT TO THE
SURFACE. THE 21.00Z NAM/GFS ARE BOTH DRY FOR SUNDAY NIGHT. AS
SUCH...HAVE KEPT A DRY FORECAST GOING. LOW CLOUD COVER CONCERN STILL
EXISTS HERE FOR SUNDAY AND SUNDAY NIGHT...ESPECIALLY IF SOME MOVE IN
BEHIND THE SATURDAY NIGHT COLD FRONT. SHOULD LOW CLOUDS MOVE
IN...LIKELY SUNDAY AND SUNDAY NIGHT WILL END UP CLOUDY. CLOUDS ARE
GOING TO INCREASE ANYWAY...ESPECIALLY SUNDAY NIGHT ASSOCIATED WITH
THE ISENTROPIC LIFT REGIME AHEAD OF THE UPPER TROUGH. GIVEN THE
UNCERTAINTY SURROUNDING CLOUD COVER ON SUNDAY...WENT WITH A BLEND OF
GUIDANCE FOR HIGHS. THE BLEND OF GUIDANCE LOOKS GOOD TOO FOR LOWS
SUNDAY NIGHT AS IT HANDLES THE CLOUD COVER INCREASE FINE.
.LONG TERM...MONDAY THROUGH THURSDAY
240 AM CST FRI DEC 21 2012
21.00Z ECMWF/GFS/CANADIAN/UKMET ARE IN FAIRLY GOOD AGREEMENT BOTH
WITH THE UPPER AND SURFACE PATTERNS THROUGHOUT THE LONG TERM PERIOD.
MAIN STORM TRACK THROUGHOUT THE LONG TERM IS SOUTH OF THE FORECAST
AREA...WHERE THERE APPEARS TO BE A STORM SYSTEM THAT CROSSES THE
SOUTHERN PLAINS INTO THE MID-ATLANTIC REGION INTO NEW ENGLAND
BETWEEN TUESDAY THROUGH THURSDAY. TRENDS CONTINUE SOUTH WITH THIS
SYSTEM...THUS ALL PRECIPITATION STAYS AWAY FROM THE FORECAST AREA.
THE ONLY SYSTEM REALLY TO DEAL WITH IS THAT UPPER TROUGH AND
INVERTED TROUGH APPROACHING THE FORECAST AREA SUNDAY NIGHT. MODELS
SUGGEST THE UPPER TROUGH IS ACTUALLY SPLIT INTO TWO PARTS...WITH THE
MAIN FEATURE/SHORTWAVE IN IT TRACKING ACROSS THE OHIO RIVER VALLEY.
WE HAVE THE NORTHERN PART OF THE TROUGH CROSSING THE FORECAST
AREA MONDAY INTO MONDAY NIGHT...BUT ALL THE BETTER MOISTURE IS WITH
THE SOUTHERN SHORTWAVE. THE 21.00Z ECMWF BASICALLY CAME IN DRY WITH
THE NORTHERN PART OF THE TROUGH AND THE 21.00Z GFS ONLY HAS SOME
VERY LIGHT QPF. GIVEN THE LACK OF MOISTURE...ESPECIALLY BELOW
700MB...ONLY HAVE 20 PERCENT CHANCES OF PRECIPITATION IN THE
FORECAST FOR MONDAY AND MONDAY NIGHT. IF TRENDS CONTINUE...THESE
COULD BE PULLED IN LATER FORECASTS.
WITH A STORM TRACK MORE TO THE SOUTH OF THE FORECAST AREA...THIS
MEANS NO WARM UPS ARE IN STORE. IN FACT...THE BULK OF THE PERIOD
SHOULD AVERAGE BELOW NORMAL AS 925MB TEMPS COOL TO -10 TO -12C FOR
TUESDAY AND WEDNESDAY BEHIND THE INVERTED TROUGH. SOME SLIGHT
WARMING SHOULD OCCUR FOR THURSDAY. SOMETHING TO WATCH IS IF WE END
UP WITH CLEAR SKIES AND LIGHT WINDS AT NIGHT...SINCE SNOW COVER IS
VERY FAVORABLE FOR HAVING TEMPERATURES PLUMMET.
&&
.AVIATION...
1100 PM CST THU DEC 20 2012
TIGHT PRESSURE GRADIENT PERSISTS THROUGH FRI MORNING...BUT WILL
SLACKEN LATER IN THE DAY AS HIGH PRESSURE BUILDS IN FROM THE WEST.
STRONG WINDS SHOULD STILL RESULT IN A FEW HOURS OF BLSN
OVERNIGHT...WITH MINOR REDUCTION IN VSBY. COULD BE SOME IMPACTS ON
RUNWAY CLEARING DUE TO THE BLOWING/DRIFTING SNOW.
LOW CIGS ARE EXPECTED TO CLEAR OVERNIGHT ALSO...ALTHOUGH LATEST
FOG/STRATUS SATELLITE IMAGERY SHOWS ANOTHER BATCH OF LOW STRATUS
SINKING SOUTHWARD ACROSS NORTHERN MN. RAP13/NAM12 TRENDS ARE TO KEEP
THE BULK OF THIS CLOUDINESS TO THE WEST/NORTHWEST...WITH SOME
DISSIPATION DURING THE DAY. KRST COULD BE IMPACTED THOUGH. WILL
LEAVE SKC-SCT FOR NOW...BUT UPDATES COULD BE NEEDED IF THE CLOUDS
TREND MORE EAST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
240 AM CST FRI DEC 21 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS TAUNTON MA
855 AM EST FRI DEC 21 2012
.SYNOPSIS...
LOW PRESSURE AND ITS ATTENDING OCCLUDED FRONT WILL BRING A
PERIOD OF HEAVY RAIN AND STRONG WINDS TO THE REGION TODAY. COLDER
TEMPS WILL FOLLOW FOR THE WEEKEND INTO EARLY NEXT WEEK. A WEAK
STORM COULD BRING SOME SNOW AND/OR RAIN ON CHRISTMAS DAY. A
STRONGER STORM MAY AFFECT NEW ENGLAND LATE WED INTO THU.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
855 AM UPDATE...
ONLY CHANGE TO THE FORECAST WAS TO EXPAND THE WIND ADVISORY INTO
SOUTHWEST/CENTRAL MA AND NORTHERN CT THROUGH MID AFTERNOON. ITS
MARGINAL...BUT WITH THE HEAVY RAIN AND STRONG SOUTHEAST LOW LEVEL
JET MAY SEE A BRIEF PERIOD OF WIND GUSTS AROUND 45 MPH. STILL THINK
THAT THIS WILL MAINLY BE AN ADVISORY LEVEL EVENT FOR MOST OF THE
REGION...AS SOUTHEAST LOW LEVEL JETS ARE OFTEN TOUGH TO MIX DOWN.
HOWEVER...IF WE CAN GENERATE A FINE LINE WILL HAVE TO WATCH FOR SOME
LOCALIZED STRONGER WIND GUSTS. WILL HAVE MORE IN A BIT.
PREVIOUS DISCUSSION...
A PERIOD OF STRONG WINDS AND HEAVY RAIN WILL
MOVE ACROSS SNE TODAY AS AN ANOMALOUS LOW LEVEL JET AHEAD OF A
STRONG OCCLUDED FRONT SWEEPS ACROSS THE REGION. THIS SYSTEM IS
RATHER PROGRESSIVE SO THE WORST OF THE WIND AND RAIN WILL LIKELY BE
CONFINED TO A 3-4 HOUR WINDOW...12-16Z IN THE WEST AND 16-20Z
EASTERN NEW ENG.
RAINFALL/FLOOD POTENTIAL...
STRONG LOW LEVEL JET 3-4SD AND +2SD PWAT ANOMALY WILL BRING A
PERIOD OF HEAVY RAIN TO SNE. HOWEVER...THIS SYSTEM WILL BE QUICK
MOVING LIMITING THE DURATION OF HEAVY RAIN IN ANY ONE LOCATION.
NAM IS THE MOST ROBUST WITH ELEVATED INSTABILITY PARAMETERS AND
SUGGEST POTENTIAL FOR SOME CONVECTION/THUNDER...AND HRRR IS
INDICATING A FINE LINE OF CONVECTION MOVING THROUGH.
HOWEVER...GFS AND ECMWF ARE RATHER WEAK WITH INSTABILITY. DUE TO
MIXED SIGNALS CONFIDENCE IN THUNDER AND ENHANCED RAINFALL RATES
IS LOW. EXPECTED RAINFALL IS 0.5" TO 1" WITH ISOLD AMOUNTS UP TO
1.5" ACROSS W ZONES WHICH WOULD MAINLY RESULT IN MINOR URBAN AND
POOR DRAINAGE FLOODING ISSUES. RAINFALL WILL BE EXITING THE REGION
FROM WEST TO EAST 16-21Z.
HIGH WIND THREAT...
MODEL DIFFERENCES IN THE STRENGTH OF THE LOW LEVEL JET INCREASES
FORECAST UNCERTAINTY REGARDING MAGNITUDE OF THE WIND THREAT. GFS
IS STRONGEST WITH THE JET INDICATING 80 KT AT 925 MB...BUT NAM HAS
TRENDED WEAKER WITH 70 KT AND ECMWF IS WEAKEST AT 60 KT. DESPITE
THESE DIFFERENCES...IMPRESSIVE PRESSURE FALLS ARE FORECAST
COINCIDENT WITH THE LOW LEVEL JET WHICH WILL ENHANCE WIND
ACCELERATION AND TEMPS ARE EXPECTED TO SPIKE INTO THE 50S IN THE
COASTAL PLAIN WHICH WILL INCREASE MIXING POTENTIAL. MODEL
SOUNDINGS ARE NOT VERY SUPPORTIVE OF STRONG WINDS MIXING
DOWN...BUT THE MILDER TEMPS AND ISALLOBARIC CONTRIBUTION SUPPORT
STRONG WINDS REACHING THE SURFACE. AS MENTIONED ABOVE WE ARE NOT
CONFIDENT IN A FINE LINE OF CONVECTION WHICH WOULD FURTHER INCREASE
HIGH WIND THREAT BUT WE HAVE ENOUGH CONFIDENCE TO GO WITH A HIGH
WIND WARNING FOR CAPE/ISLANDS WHERE STRONGEST LOW LEVEL WINDS ARE
EXPECTED. ELSEWHERE WE WILL GO WITH A WIND ADVISORY FOR RI AND
EASTERN MA. TIMING OF STRONGEST WINDS WILL BE 14-17Z RI AND
16-19Z E MA AND CAPE/ISLANDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
MID LEVEL LOW MOVES INTO CENTRAL AND NORTHERN NEW ENG TONIGHT WITH
A STRONG SHORTWAVE ROTATING INTO THE REGION TOWARD MIDNIGHT. AS A
RESULT WE EXPECT SCT SNOW/RAIN SHOWERS TO REDEVELOP. BL TEMPS WILL
BE MARGINAL NEAR THE COAST WHERE ANY PRECIP MAY BE IN THE FORM OF
RAIN...BUT EXPECT MOSTLY SNOW SHOWERS ELSEWHERE. CANT RULE OUT
MINOR ACCUM IN THE HIGHER TERRAIN.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
HIGHLIGHTS...
* ARCTIC AIR MOVES IN BEHIND THE LOW PRES THROUGH THE WEEKEND
* WEAK LOW PRES MAY BRING LIGHT SNOW ON CHRISTMAS DAY
* STRONG STORM POSSIBLE WED NIGHT INTO THU
OVERVIEW AND MODEL PREFERENCES...
21/00Z MODEL GUIDANCE SUITE CONTINUES TO SHOW DECENT SYNOPTIC
SCALE AGREEMENT THROUGH THE EARLY PORTION OF THE LONG TERM BUT ARE
STRUGGLING WITH TWO DIFFERENT SYSTEMS AFFECTING THE MID AND LONG
TERM SENSIBLE WX DETAILS. ECMWF HAS COME IN LINE WITH GFS/NAM
TIMING FOR THE LOW PRES THIS WEEKEND EXITING INTO THE
MARITIMES...SO WILL CONTINUE TO BASELINE FORECAST USING GFS AS IT
HAS SHOWN MORE CONSISTENCY. THE DISAGREEMENTS BEGIN REGARDING
WITH THE E CANADA FLOW PATTERN FOR THE CHRISTMAS EVE/DAY SYSTEM. A
SPAGHETTI PLOT OF OPERATIONAL LONG RANGE GUIDANCE AND ENSEMBLES
AT H5 ARE ALL OVER THE PLACE WITH THE NRN NEW ENGLAND E CANADA
FLOW PATTERN...SO STILL NOT A LOT OF CONFIDENCE IN WHETHER OR NOT
HIGH PRES TO THE N WILL SUPPRESS LIGHT SNOW FOR CHRISTMAS EVE TO
THE S. THE LATEST ECMWF IS CLOSER TO THE SOLUTION SUGGESTED BY THE
GFS AND A FEW GEFS MEMBERS. WILL LEAN ON HPC AS FOR NOW GIVEN THE
DIFFERENCES AND ISSUES WITH UPPER LVL FLOW PATTERN. IN REGARDS TO
THE MID WEEK SYSTEM NEXT WEEK...GUIDANCE IS ACTUALLY IN DECENT
AGREEMENT WITH THE DEEPENING/SHARPENING WAVE MOVING E FROM THE
ROCKIES AGAIN...BUT GENERATE VERY DIFFERENT SFC CYCLONES. ECMWF
CONTINUES TO BE SIMILAR TO THE SYSTEM FOR TODAY AND THE WEEKEND
WHILE GFS PUSHES THE LOW NEAR THE 40/70 BENCHMARK. HPC LEANS
TOWARD THE ECENS THIS STRETCH...WHICH IS COOLER THAN THE
OPERATIONAL ECMWF...BUT WARMER THAN THE GFS...SO GIVEN THIS IS A
GOOD COMPROMISE...WILL CONTINUE TO USE IT FOR THE MID-LATE WEEK
SYSTEM.
DETAILS...
SAT INTO MON...
SLOW MOVING CUTOFF LOW PRES AND ITS WEAKENING SFC LOW WILL
GRADUALLY BE SHIFTING INTO THE MARITIMES THROUGH THE PERIOD. THIS
WILL ALLOW A MUCH COLDER AIRMASS TO MOVE IN WITH H92 TEMPS
AVERAGING THE -5C TO -8C RANGE. THEREFORE...WITH SOME REMNANT
ENERGY WRAPPING AROUND AND LOW LVL MOISTURE WRAPPING AROUND THE
LOW SAT...A FEW SNOW SHOWERS ARE LIKELY WHICH GIVEN COOLER SFC
TEMPS MAY ACCUMULATE IN SPOTS. GENERALLY AN INCH OR LESS
ACCUMULATION IS EXPECTED AT ANY GIVEN LOCATION. WITH DRY/COLD
AIRMASS SHIFTING INTO THE REGION...SUN AND MON ARE EXPECTED TO BE
MOSTLY DRY...BUT ON THE COLDER SIDE OF SEASONABLE FOR
TEMPERATURES.
MON NIGHT INTO TUE NIGHT...
GIVEN THE UNCERTAINTY HERE...THERE ARE STILL SOME QUESTIONS TO BE
ANSWERED REGARDING WEAK LOW PRES PASSING TO THE S OF SRN NEW
ENGLAND. SOUNDINGS AND DIVERGENCE FIELDS SHOW A WEAK TROWAL
WRAPPING TO THE N WITH TEMP PROFILES COOL ENOUGH FOR SNOW RIGHT TO
THE S COAST. GIVEN THE UNCERTAINTY HOWEVER...THERE COULD BE A
SHARP CUTOFF BETWEEN THOSE THAT SEE SOME OF THE WHITE FOR
CHRISTMAS AND THOSE THAT DON/T AND IT IS STILL POSSIBLE IT MAY BE
DRY ACROSS THE BOARD WITH STRONG HIGH PRES TO THE N. THE HPC STILL
FAVORS AREAS S OF THE MASS PIKE...SO WILL CONTINUE WITH THIS
SUGGESTION FOR THIS FORECAST UPDATE.
WED AND THU...
A MUCH MORE DYNAMIC SYSTEM WILL APPROACH FOR THE MID TO LATE WEEK
TIMEFRAME. GIVEN THE WIDE ENVELOPE OF SOLUTIONS FOR THIS WHICH
WILL HAVE SIGNIFICANT DIFFERENCES IN SENSIBLE WX DETAILS /GUIDANCE
RANGES FROM AN ALL RAIN TO AN ALL SNOW EVENT/. WILL TREND TOWARD
HPC WHICH IS AN ECENS BASES SOLUTION AT THIS TIME. THIS
COMPROMISES WITH SOME SNOW TO THE N AND RAIN IN THE S.
HOWEVER...NEITHER ALL SNOW OR ALL RAIN SOLUTIONS CAN/T BE RULED
OUT AND WILL HAVE TO BE MONITORED ESPECIALLY ONCE THE WAVE ITS
ASSOCIATED WITH CAN BE SAMPLED OVER LAND OBSERVING SITES.
FRI...
MODEL GUIDANCE DOES SUGGEST THAT IN ANY CASE...COOL HIGH PRES
WILL BE BUILDING IN TOWARD THE END OF THE WEEK...SO WILL LEAN
GUIDANCE IN THIS SOLUTION FOR THE EXTENDED PERIOD.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...HIGH CONFIDENCE.
A MAINLY MVFR/IFR TO START THIS MORNING...BUT IT IS EXPECTED THAT
THE TREND WILL BE TOWARD IFR AS A BAND OF RAIN AND STRONG WINDS
MOVE THROUGH THIS MORNING AND EARLY AFTERNOON FROM WEST TO EAST.
AFTER THE RAIN MOVES OUT...COULD SEE A RAPID IMPROVEMENT TO VFR
THROUGH THE EVENING BEFORE FOG BUILDS OVER AGAIN TONIGHT WITH
VSBYS DIPPING BACK TO THE MVFR/IFR LVLS. WINDS WILL BE STRONG
TODAY OUT OF THE SE...GUSTS 30-40 IN THE INTERIOR WITH NEAR
COASTAL TERMINALS SEEING 40-50 KT GUSTS AT TIMES. WINDS RAPIDLY
SHIFT TO THE WSW AFTER RAIN MOVES OUT.
KBOS TAF...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN EXACT
TIMING IN TAFS.
TREND WILL BE TOWARD A PERIOD OF IFR THROUGH MID AFTERNOON WITH
RAIN AND LOW CIGS. WINDS WILL ALSO BE STRONG OUT OF THE SW GUSTING
AS HIGH AS 40-50 KT BY LATE MORNING/EARLY AFTERNOON. RAPID
IMPROVEMENT TO VFR AFTER WINDS DIMINISH A BIT AND SHIFT TO WSW.
LLWS MUCH OF THE EARLY PORTION OF THE DAY
KBDL TAF...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN EXACT
TIMING.
TREND WILL BE TOWARD A PERIOD OF IFR THROUGH THE EARLY AFTERNOON
WITH STRONG WINDS 16Z-19Z /GUSTS AROUND 30 KT/. ONCE WINDS SHIFT
TO THE WSW...EXPECT THEM TO DIMINISH AND FOR A LIFT TO VFR INTO
THE EVENING.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY INTO SATURDAY NIGHT...MODERATE CONFIDENCE.
MAINLY VFR. HOWEVER...OCCASIONAL RAIN AND SNOW SHOWERS COULD
REDUCE BOTH VSBYS AND CIGS TO MVFR. WINDS GUST 30-40 KT OUT OF
THE NW SAT NIGHT.
SUNDAY AND MONDAY...HIGH CONFIDENCE.
VFR. NW WINDS GUST 20-30 KT THROUGH THE DAY ON SUN.
TUESDAY...MODERATE CONFIDENCE.
MAINLY VFR....BUT LIGHT SNOW IS POSSIBLE EARLY TUESDAY ESPECIALLY
TERMINALS S OF THE MASS PIKE.
&&
.MARINE...
MODERATE TO HIGH CONFIDENCE THROUGH TONIGHT.
A BRIEF PERIOD OF STORM FORCE SE WIND GUSTS TO NEAR 50 KT IS
EXPECTED FROM WEST TO EAST 14-20Z. STORM WARNINGS CONTINUE EXCEPT
STRONG GALES FOR NARR BAY AND BOSTON HARBOR. RAIN...HEAVY AT TIMES
IMPROVING FROM WEST TO EAST DURING THE AFTERNOON.
WINDS WILL DIMINISH WITH THE WIND SHIFT TO SW LATER THIS AFTERNOON
BUT STILL EXPECT WIND GUSTS TO 30 KT TONIGHT.
OUTLOOK...SATURDAY THROUGH TUESDAY...
MODERATE TO HIGH CONFIDENCE THROUGH TUESDAY.
SAT INTO SAT NIGHT...MODERATE CONFIDENCE.
WINDS BRIEFLY DIP TO SMALL CRAFT LEVELS DURING THE DAY
SATURDAY...BUT THEN ONCE WINDS SHIFT TO THE NW EXPECT GALE FORCE
GUSTS TO RETURN ESPECIALLY SAT NIGHT INTO EARLY SUNDAY. SEAS
REMAIN ELEVATED.
SUN INTO MON...HIGH CONFIDENCE.
BOTH WINDS AND SEAS GRADUALLY DIMINISH THROUGH THE PERIOD.
ALTHOUGH EXPECTING SMALL CRAFT WINDS THROUGH SUN NIGHT. BY
MON...SEAS AND WINDS SHOULD DROP BELOW SCA THRESHOLDS.
TUE...MODERATE CONFIDENCE.
WINDS AND SEAS START BELOW SMALL CRAFT THRESHOLDS...BUT MAY SEE
25 KT GUSTS AND SEAS NEAR 5 FT OVER SRN OUTER WATERS BY TUE
AFTERNOON AS A WEAK LOW PRES PASSES S OF THE REGION.
&&
.TIDES/COASTAL FLOODING...
NOT EXPECTING ANY COASTAL FLOODING OR BEACH EROSION AS ASTRO
TIDES ARE VERY LOW.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR CTZ002>004.
MA...WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR MAZ004>007-009-
011>021-026.
HIGH WIND WARNING UNTIL 4 PM EST THIS AFTERNOON FOR MAZ022>024.
NH...NONE.
RI...HIGH WIND WARNING UNTIL 1 PM EST THIS AFTERNOON FOR RIZ008.
WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR RIZ001>007.
MARINE...STORM WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ANZ231>234-250-
251-254-255.
GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ANZ230-236.
STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR ANZ235-237-256.
&&
$$
SYNOPSIS...KJC/DOODY
NEAR TERM...FRANK/KJC/DOODY
SHORT TERM...KJC
LONG TERM...DOODY
AVIATION...KJC/DOODY
MARINE...KJC/DOODY
TIDES/COASTAL FLOODING...STAFF
AREA FORECAST DISCUSSION
NWS TAUNTON MA
656 AM EST FRI DEC 21 2012
.SYNOPSIS...
LOW PRESSURE AND ITS ATTENDING OCCLUDED FRONT WILL BRING A
PERIOD OF HEAVY RAIN AND STRONG WINDS TO THE REGION TODAY. COLDER
TEMPS WILL FOLLOW FOR THE WEEKEND INTO EARLY NEXT WEEK. A WEAK
STORM COULD BRING SOME SNOW AND/OR RAIN ON CHRISTMAS DAY. A
STRONGER STORM MAY AFFECT NEW ENGLAND LATE WED INTO THU.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
7 AM UPDATE...
INITIAL ISENTROPICALLY GENERATED PRECIP IS SHIFTING OFFSHORE THIS
HOUR AS NEW BAND OF RAINFALL BEGINS TO FILL IN FROM THE SW. THIS
SECOND BATCH IS ASSOCIATED WITH THE INITIAL NOSE OF A 70 KT H92
LLJ WHICH WILL BEGIN MOVING OVER THE AREA FROM W TO E THROUGH THE
MORNING. EXPECTING THE STRONG WINDS TO SHIFT TO THE E ALONG WITH
THIS JET AS WELL AS THE CHANCE FOR HEAVIEST RAINFALL. HAVE
ADJUSTED TIMING SOMEWHAT TOWARD THE LATEST RAP...WHICH HAS CAUGHT
ON WELL IN THE LAST COUPLE OF HOURS. ADJUSTED POPS/WX TOWARD THE
RAP TIMING. UPSTREAM RADARS ARE SHOWING A WEAK LINE OF LOW TOPPED
CONVECTION ASSOCIATED WITH THE TRIPLE POINT LOW AND
OCCLUSION...MAY NEED TO MONITOR THIS FOR ANY ERD MOVEMENT AS IT
COULD ENHANCE MIXING DOWN OF THE JET.
PREVIOUS DISCUSSION...
SNOW IN THE DISTANT INTERIOR HAS ACCUMULATED 1-2 INCHES. IT IS
STILL SNOWING ACROSS WESTERN AND NORTHERN MA INTO S NH WITH TEMPS
32-34 DEGREES. HOWEVER...LOW LEVEL WARMING WILL RESULT IN A QUICK
CHANGEOVER TO RAIN THROUGH 6 AM. ADDITIONAL ACCUMULATION UP TO AN
INCH IS POSSIBLE.
A PERIOD OF STRONG WINDS AND HEAVY RAIN WILL MOVE ACROSS SNE
TODAY AS AN ANOMALOUS LOW LEVEL JET AHEAD OF A STRONG OCCLUDED
FRONT SWEEPS ACROSS THE REGION. THIS SYSTEM IS RATHER PROGRESSIVE
SO THE WORST OF THE WIND AND RAIN WILL LIKELY BE CONFINED TO A 3-4
HOUR WINDOW...12-16Z IN THE WEST AND 16-20Z EASTERN NEW ENG.
RAINFALL/FLOOD POTENTIAL...
STRONG LOW LEVEL JET 3-4SD AND +2SD PWAT ANOMALY WILL BRING A
PERIOD OF HEAVY RAIN TO SNE. HOWEVER...THIS SYSTEM WILL BE QUICK
MOVING LIMITING THE DURATION OF HEAVY RAIN IN ANY ONE LOCATION.
NAM IS THE MOST ROBUST WITH ELEVATED INSTABILITY PARAMETERS AND
SUGGEST POTENTIAL FOR SOME CONVECTION/THUNDER...AND HRRR IS
INDICATING A FINE LINE OF CONVECTION MOVING THROUGH.
HOWEVER...GFS AND ECMWF ARE RATHER WEAK WITH INSTABILITY. DUE TO
MIXED SIGNALS CONFIDENCE IN THUNDER AND ENHANCED RAINFALL RATES
IS LOW. EXPECTED RAINFALL IS 0.5" TO 1" WITH ISOLD AMOUNTS UP TO
1.5" ACROSS W ZONES WHICH WOULD MAINLY RESULT IN MINOR URBAN AND
POOR DRAINAGE FLOODING ISSUES. RAINFALL WILL BE EXITING THE REGION
FROM WEST TO EAST 16-21Z.
HIGH WIND THREAT...
MODEL DIFFERENCES IN THE STRENGTH OF THE LOW LEVEL JET INCREASES
FORECAST UNCERTAINTY REGARDING MAGNITUDE OF THE WIND THREAT. GFS
IS STRONGEST WITH THE JET INDICATING 80 KT AT 925 MB...BUT NAM HAS
TRENDED WEAKER WITH 70 KT AND ECMWF IS WEAKEST AT 60 KT. DESPITE
THESE DIFFERENCES...IMPRESSIVE PRESSURE FALLS ARE FORECAST
COINCIDENT WITH THE LOW LEVEL JET WHICH WILL ENHANCE WIND
ACCELERATION AND TEMPS ARE EXPECTED TO SPIKE INTO THE 50S IN THE
COASTAL PLAIN WHICH WILL INCREASE MIXING POTENTIAL. MODEL
SOUNDINGS ARE NOT VERY SUPPORTIVE OF STRONG WINDS MIXING
DOWN...BUT THE MILDER TEMPS AND ISALLOBARIC CONTRIBUTION SUPPORT
STRONG WINDS REACHING THE SURFACE. AS MENTIONED ABOVE WE ARE NOT
CONFIDENT IN A FINE LINE OF CONVECTION WHICH WOULD FURTHER INCREASE
HIGH WIND THREAT BUT WE HAVE ENOUGH CONFIDENCE TO GO WITH A HIGH
WIND WARNING FOR CAPE/ISLANDS WHERE STRONGEST LOW LEVEL WINDS ARE
EXPECTED. ELSEWHERE WE WILL GO WITH A WIND ADVISORY FOR RI AND
EASTERN MA. TIMING OF STRONGEST WINDS WILL BE 14-17Z RI AND
16-19Z E MA AND CAPE/ISLANDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
MID LEVEL LOW MOVES INTO CENTRAL AND NORTHERN NEW ENG TONIGHT WITH
A STRONG SHORTWAVE ROTATING INTO THE REGION TOWARD MIDNIGHT. AS A
RESULT WE EXPECT SCT SNOW/RAIN SHOWERS TO REDEVELOP. BL TEMPS WILL
BE MARGINAL NEAR THE COAST WHERE ANY PRECIP MAY BE IN THE FORM OF
RAIN...BUT EXPECT MOSTLY SNOW SHOWERS ELSEWHERE. CANT RULE OUT
MINOR ACCUM IN THE HIGHER TERRAIN.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
HIGHLIGHTS...
* ARCTIC AIR MOVES IN BEHIND THE LOW PRES THROUGH THE WEEKEND
* WEAK LOW PRES MAY BRING LIGHT SNOW ON CHRISTMAS DAY
* STRONG STORM POSSIBLE WED NIGHT INTO THU
OVERVIEW AND MODEL PREFERENCES...
21/00Z MODEL GUIDANCE SUITE CONTINUES TO SHOW DECENT SYNOPTIC
SCALE AGREEMENT THROUGH THE EARLY PORTION OF THE LONG TERM BUT ARE
STRUGGLING WITH TWO DIFFERENT SYSTEMS AFFECTING THE MID AND LONG
TERM SENSIBLE WX DETAILS. ECMWF HAS COME IN LINE WITH GFS/NAM
TIMING FOR THE LOW PRES THIS WEEKEND EXITING INTO THE
MARITIMES...SO WILL CONTINUE TO BASELINE FORECAST USING GFS AS IT
HAS SHOWN MORE CONSISTENCY. THE DISAGREEMENTS BEGIN REGARDING
WITH THE E CANADA FLOW PATTERN FOR THE CHRISTMAS EVE/DAY SYSTEM. A
SPAGHETTI PLOT OF OPERATIONAL LONG RANGE GUIDANCE AND ENSEMBLES
AT H5 ARE ALL OVER THE PLACE WITH THE NRN NEW ENGLAND E CANADA
FLOW PATTERN...SO STILL NOT A LOT OF CONFIDENCE IN WHETHER OR NOT
HIGH PRES TO THE N WILL SUPPRESS LIGHT SNOW FOR CHRISTMAS EVE TO
THE S. THE LATEST ECMWF IS CLOSER TO THE SOLUTION SUGGESTED BY THE
GFS AND A FEW GEFS MEMBERS. WILL LEAN ON HPC AS FOR NOW GIVEN THE
DIFFERENCES AND ISSUES WITH UPPER LVL FLOW PATTERN. IN REGARDS TO
THE MID WEEK SYSTEM NEXT WEEK...GUIDANCE IS ACTUALLY IN DECENT
AGREEMENT WITH THE DEEPENING/SHARPENING WAVE MOVING E FROM THE
ROCKIES AGAIN...BUT GENERATE VERY DIFFERENT SFC CYCLONES. ECMWF
CONTINUES TO BE SIMILAR TO THE SYSTEM FOR TODAY AND THE WEEKEND
WHILE GFS PUSHES THE LOW NEAR THE 40/70 BENCHMARK. HPC LEANS
TOWARD THE ECENS THIS STRETCH...WHICH IS COOLER THAN THE
OPERATIONAL ECMWF...BUT WARMER THAN THE GFS...SO GIVEN THIS IS A
GOOD COMPROMISE...WILL CONTINUE TO USE IT FOR THE MID-LATE WEEK
SYSTEM.
DETAILS...
SAT INTO MON...
SLOW MOVING CUTOFF LOW PRES AND ITS WEAKENING SFC LOW WILL
GRADUALLY BE SHIFTING INTO THE MARITIMES THROUGH THE PERIOD. THIS
WILL ALLOW A MUCH COLDER AIRMASS TO MOVE IN WITH H92 TEMPS
AVERAGING THE -5C TO -8C RANGE. THEREFORE...WITH SOME REMNANT
ENERGY WRAPPING AROUND AND LOW LVL MOISTURE WRAPPING AROUND THE
LOW SAT...A FEW SNOW SHOWERS ARE LIKELY WHICH GIVEN COOLER SFC
TEMPS MAY ACCUMULATE IN SPOTS. GENERALLY AN INCH OR LESS
ACCUMULATION IS EXPECTED AT ANY GIVEN LOCATION. WITH DRY/COLD
AIRMASS SHIFTING INTO THE REGION...SUN AND MON ARE EXPECTED TO BE
MOSTLY DRY...BUT ON THE COLDER SIDE OF SEASONABLE FOR
TEMPERATURES.
MON NIGHT INTO TUE NIGHT...
GIVEN THE UNCERTAINTY HERE...THERE ARE STILL SOME QUESTIONS TO BE
ANSWERED REGARDING WEAK LOW PRES PASSING TO THE S OF SRN NEW
ENGLAND. SOUNDINGS AND DIVERGENCE FIELDS SHOW A WEAK TROWAL
WRAPPING TO THE N WITH TEMP PROFILES COOL ENOUGH FOR SNOW RIGHT TO
THE S COAST. GIVEN THE UNCERTAINTY HOWEVER...THERE COULD BE A
SHARP CUTOFF BETWEEN THOSE THAT SEE SOME OF THE WHITE FOR
CHRISTMAS AND THOSE THAT DON/T AND IT IS STILL POSSIBLE IT MAY BE
DRY ACROSS THE BOARD WITH STRONG HIGH PRES TO THE N. THE HPC STILL
FAVORS AREAS S OF THE MASS PIKE...SO WILL CONTINUE WITH THIS
SUGGESTION FOR THIS FORECAST UPDATE.
WED AND THU...
A MUCH MORE DYNAMIC SYSTEM WILL APPROACH FOR THE MID TO LATE WEEK
TIMEFRAME. GIVEN THE WIDE ENVELOPE OF SOLUTIONS FOR THIS WHICH
WILL HAVE SIGNIFICANT DIFFERENCES IN SENSIBLE WX DETAILS /GUIDANCE
RANGES FROM AN ALL RAIN TO AN ALL SNOW EVENT/. WILL TREND TOWARD
HPC WHICH IS AN ECENS BASES SOLUTION AT THIS TIME. THIS
COMPROMISES WITH SOME SNOW TO THE N AND RAIN IN THE S.
HOWEVER...NEITHER ALL SNOW OR ALL RAIN SOLUTIONS CAN/T BE RULED
OUT AND WILL HAVE TO BE MONITORED ESPECIALLY ONCE THE WAVE ITS
ASSOCIATED WITH CAN BE SAMPLED OVER LAND OBSERVING SITES.
FRI...
MODEL GUIDANCE DOES SUGGEST THAT IN ANY CASE...COOL HIGH PRES
WILL BE BUILDING IN TOWARD THE END OF THE WEEK...SO WILL LEAN
GUIDANCE IN THIS SOLUTION FOR THE EXTENDED PERIOD.
&&
.AVIATION /11Z FRIDAY THROUGH TUESDAY/...
SHORT TERM...HIGH CONFIDENCE.
A MAINLY MVFR/IFR TO START THIS MORNING...BUT IT IS EXPECTED THAT
THE TREND WILL BE TOWARD IFR AS A BAND OF RAIN AND STRONG WINDS
MOVE THROUGH THIS MORNING AND EARLY AFTERNOON FROM WEST TO EAST.
AFTER THE RAIN MOVES OUT...COULD SEE A RAPID IMPROVEMENT TO VFR
THROUGH THE EVENING BEFORE FOG BUILDS OVER AGAIN TONIGHT WITH
VSBYS DIPPING BACK TO THE MVFR/IFR LVLS. WINDS WILL BE STRONG
TODAY OUT OF THE SE...GUSTS 30-40 IN THE INTERIOR WITH NEAR
COASTAL TERMINALS SEEING 40-50 KT GUSTS AT TIMES. WINDS RAPIDLY
SHIFT TO THE WSW AFTER RAIN MOVES OUT.
KBOS TAF...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN EXACT
TIMING IN TAFS.
TREND WILL BE TOWARD A PERIOD OF IFR THROUGH MID AFTERNOON WITH
RAIN AND LOW CIGS. WINDS WILL ALSO BE STRONG OUT OF THE SW GUSTING
AS HIGH AS 40-50 KT BY LATE MORNING/EARLY AFTERNOON. RAPID
IMPROVEMENT TO VFR AFTER WINDS DIMINISH A BIT AND SHIFT TO WSW.
LLWS MUCH OF THE EARLY PORTION OF THE DAY
KBDL TAF...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN EXACT
TIMING.
TREND WILL BE TOWARD A PERIOD OF IFR THROUGH THE EARLY AFTERNOON
WITH STRONG WINDS 16Z-19Z /GUSTS AROUND 30 KT/. ONCE WINDS SHIFT
TO THE WSW...EXPECT THEM TO DIMINISH AND FOR A LIFT TO VFR INTO
THE EVENING.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY INTO SATURDAY NIGHT...MODERATE CONFIDENCE.
MAINLY VFR. HOWEVER...OCCASIONAL RAIN AND SNOW SHOWERS COULD
REDUCE BOTH VSBYS AND CIGS TO MVFR. WINDS GUST 30-40 KT OUT OF
THE NW SAT NIGHT.
SUNDAY AND MONDAY...HIGH CONFIDENCE.
VFR. NW WINDS GUST 20-30 KT THROUGH THE DAY ON SUN.
TUESDAY...MODERATE CONFIDENCE.
MAINLY VFR....BUT LIGHT SNOW IS POSSIBLE EARLY TUESDAY ESPECIALLY
TERMINALS S OF THE MASS PIKE.
&&
.MARINE...
MODERATE TO HIGH CONFIDENCE THROUGH TONIGHT.
A BRIEF PERIOD OF STORM FORCE SE WIND GUSTS TO NEAR 50 KT IS
EXPECTED FROM WEST TO EAST 14-20Z. STORM WARNINGS CONTINUE EXCEPT
STRONG GALES FOR NARR BAY AND BOSTON HARBOR. RAIN...HEAVY AT TIMES
IMPROVING FROM WEST TO EAST DURING THE AFTERNOON.
WINDS WILL DIMINISH WITH THE WIND SHIFT TO SW LATER THIS AFTERNOON
BUT STILL EXPECT WIND GUSTS TO 30 KT TONIGHT.
OUTLOOK...SATURDAY THROUGH TUESDAY...
MODERATE TO HIGH CONFIDENCE THROUGH TUESDAY.
SAT INTO SAT NIGHT...MODERATE CONFIDENCE.
WINDS BRIEFLY DIP TO SMALL CRAFT LEVELS DURING THE DAY
SATURDAY...BUT THEN ONCE WINDS SHIFT TO THE NW EXPECT GALE FORCE
GUSTS TO RETURN ESPECIALLY SAT NIGHT INTO EARLY SUNDAY. SEAS
REMAIN ELEVATED.
SUN INTO MON...HIGH CONFIDENCE.
BOTH WINDS AND SEAS GRADUALLY DIMINISH THROUGH THE PERIOD.
ALTHOUGH EXPECTING SMALL CRAFT WINDS THROUGH SUN NIGHT. BY
MON...SEAS AND WINDS SHOULD DROP BELOW SCA THRESHOLDS.
TUE...MODERATE CONFIDENCE.
WINDS AND SEAS START BELOW SMALL CRAFT THRESHOLDS...BUT MAY SEE
25 KT GUSTS AND SEAS NEAR 5 FT OVER SRN OUTER WATERS BY TUE
AFTERNOON AS A WEAK LOW PRES PASSES S OF THE REGION.
&&
.TIDES/COASTAL FLOODING...
NOT EXPECTING ANY COASTAL FLOODING OR BEACH EROSION AS ASTRO
TIDES ARE VERY LOW.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...WIND ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR MAZ005>007-
013>021.
HIGH WIND WARNING UNTIL 4 PM EST THIS AFTERNOON FOR MAZ022>024.
NH...NONE.
RI...HIGH WIND WARNING UNTIL 1 PM EST THIS AFTERNOON FOR RIZ008.
WIND ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR RIZ001>007.
MARINE...STORM WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ANZ231>234-250-
251-254-255.
GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ANZ230-236.
STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR ANZ235-237-256.
&&
$$
SYNOPSIS...KJC/DOODY
NEAR TERM...KJC/DOODY
SHORT TERM...KJC
LONG TERM...DOODY
AVIATION...KJC/DOODY
MARINE...KJC/DOODY
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
1055 AM EST FRI DEC 21 2012
...A WINTER FEEL TO THE FORECAST THE NEXT COUPLE OF DAYS...
.UPDATE...
15Z WATER VAPOR AND H4 RAP ANALYSIS CONTINUES TO SHOW A HIGHLY
AMPLIFIED UPPER LEVEL PATTERN OVER THE CONUS. PATTERN CONSISTS OF
TROUGHING BEGINNING TO MOVE ASHORE ALONG THE PACIFIC COASTLINE
FOLLOWED DOWNSTREAM BY LONGWAVE RIDGING ACROSS THE INTERMOUNTAIN
WEST AND HIGH PLAINS. THE FLOW THE SHARPLY DIPS BACK TO THE SOUTH
INTO AND IMPRESSIVE NEGATIVELY TILTED TROUGH AND CLOSED LOW FEATURE
COVERING THE EASTERN THIRD OF THE NATION. ASSOCIATED WITH THIS
PARENT ENERGY WE FIND STRONG 982MB SURFACE LOW PRESSURE OVER THE
NORTHEASTERN STATES WITH A COLD FRONT TRAILING OFF THE ATLANTIC
SEABOARD ALL THE WAY DOWN TO THE THE BAHAMAS AND CENTRAL CUBA.
THIS COLD FRONT RAPIDLY PUSHED ACROSS OUR FORECAST AREA LAST NIGHT
WITH A NARROW BAND OF CONVECTION. THAT RAINFALL IS LONG GONE AS A
MUCH COLDER AND DRIER AIRMASS IS ARRIVING ON GUSTY NORTHWEST WINDS.
TIME-HEIGHT ANALYSIS SHOWS A DEEP LAYER OF VERY DRY AIR ABOVE THE
SURFACE THROUGH THE REMAINDER OF THE DAY THAT WILL KEEP OUR SKIES
CLEAR TO MOSTLY CLEAR. DESPITE THE ABUNDANT SUNSHINE AND GOOD
MIXING...THE CAA WILL SLOW THE TEMPERATURE RISE AND EXPECT HIGH
TEMPS TO STRUGGLE TOWARD 60 NORTH OF BROOKSVILLE AND ONLY INTO THE
LOWER/MIDDLE 60S FURTHER SOUTH. THE STRONG NW WINDS UP TO 30 KNOTS
IS PUSHING A DECENT SWELL TOWARD THE COAST AND SURF HEIGHTS AT AREA
BEACHES HAVE REACHED 4-6 FEET PROMPTING A HIGH SURF ADVISORY THROUGH
THE REMAINDER OF THE AFTERNOON/EARLY EVENING. THE RIP CURRENT RISK
IS ALSO HIGH AS A RESULT OF THIS SURF.
TONIGHT...A COLD/CHILLY NIGHT ON TAP. HIGH PRESSURE WILL STILL BE
CENTERED WELL TO OUR WEST. THERE IS A RIDGE AXIS THAT EXTENDS OVER
TOWARD US...BUT THE GRADIENT WILL NOT RELAX ENOUGH OVER MUCH OF THE
AREA TO ALLOW FOR MUCH OF A RADIATIVE COMPONENT TO THE TEMPERATURE
DROP. WILL BE LOOKING AT MORE OF AN ADVECTION DROP IN TEMPS WITH
SOME COLD AIR DRAINAGE FROM THE NORTH DOWN THE PENINSULA. CURRENT
FORECAST IS LOOKING FOR WIDESPREAD LOWER TO MIDDLE 30S AWAY FROM THE
IMMEDIATE COAST...AND EVEN COLDER (MID 20S TO AROUND 30) OVER THE
INTERIOR NATURE COAST ZONES. A FREEZE WARNING REMAINS IN EFFECT FOR
THE NATURE COAST ZONES LATE TONIGHT INTO EARLY SATURDAY MORNING FOR
SEVERAL HOURS OF SUB-FREEZING TEMPS. ALTHOUGH A FREEZE WARNING IS
NOT CURRENTLY IN EFFECT FURTHER SOUTH...TEMPERATURES MAY BRIEFLY
APPROACH 32 IN SPOTS. DEWPOINT DEPRESSIONS LATE TONIGHT ARE 6-10C
WHICH ALONG WITH A LIGHT WIND SHOULD PREVENT ANY SIGNIFICANT FROST
FORMATION. AN APPROACHING UPPER LEVEL JET FROM THE NORTHWEST WILL
LIKELY BRING IN SOME THIN HIGH CLOUDS FROM THE WEST DURING THE
OVERNIGHT...HOWEVER WITH THIS NOT BEING A RADIATIONAL COOLING
EVENT...THESE HIGH CLOUDS SHOULD HAVE LITTLE IMPACT ON THE TEMP
FORECAST. WILL MAKE A FINAL DECISION BASED ON THE AFTERNOON FORECAST
PACKAGE NUMBERS...HOWEVER THE COMBINATION OF LOW TEMPERATURES AND AT
LEAST SOME WIND STAYING UP OVERNIGHT MAY REQUIRE THE ISSUANCE OF A
WIND CHILL ADVISORY FOR JUST ABOUT ALL OF THE FORECAST AREA. THE
ADVISORY CRITERIA ARE MOST LIKELY TO BE MET AFTER MIDNIGHT INTO THE
FIRST 1-2 DAYLIGHT HOURS OF SATURDAY. STAY WARM...AND WELCOME TO
OFFICIAL WINTER.
&&
.AVIATION...
STRONG COLD FRONT HAS CLEARED ALL TERMINALS NOW WITH VFR CONDITIONS
AND GUSTY NORTH TO NORTHWESTERLY WINDS EXPECTED FOR THE REMAINDER OF
THE DAY.
&&
.MARINE...
A COLD FRONT EXITED THE FORECAST WATERS EARLY THIS MORNING. ADVISORY
LEVEL CONDITIONS ARE ONGOING ACROSS THE EASTERN GULF OF MEXICO AND
PERIODS OF GALE CONDITIONS REMAIN POSSIBLE THROUGH THE AFTERNOON.
ANY GALE FORCE GUSTS SHOULD END BY EARLY EVENING...HOWEVER ADVISORY
CRITERIA WINDS AND SEAS WILL PERSIST THROUGH LATE TONIGHT OR EARLY
SATURDAY. THE HIGH WILL MOVE ACROSS THE REGION DURING THE WEEKEND
AND ALLOW WINDS AND SEAS TO SUBSIDE. THE NEXT COLD FRONT IS
ANTICIPATED DURING EARLY TO MID NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 62 40 62 42 / 0 0 0 0
FMY 66 40 65 42 / 0 0 0 0
GIF 62 36 61 41 / 0 0 0 0
SRQ 64 41 62 43 / 0 0 0 0
BKV 61 29 60 31 / 0 0 0 0
SPG 62 49 61 48 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY
MORNING FOR CITRUS-HERNANDO-LEVY-PASCO-SUMTER.
LAKE WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR
CHARLOTTE-CITRUS-DESOTO-HARDEE-HERNANDO-HIGHLANDS-
HILLSBOROUGH-LEE-LEVY-MANATEE-PASCO-PINELLAS-POLK-
SARASOTA-SUMTER.
FREEZE WARNING FROM 2 AM TO 9 AM EST SATURDAY FOR CITRUS-
HERNANDO-LEVY-PASCO-SUMTER.
FIRE WEATHER WATCH SATURDAY AFTERNOON FOR CHARLOTTE-CITRUS-
DESOTO-HARDEE-HERNANDO-HIGHLANDS-HILLSBOROUGH-LEE-
LEVY-MANATEE-PASCO-PINELLAS-POLK-SARASOTA-SUMTER.
RED FLAG WARNING UNTIL 6 PM EST THIS EVENING FOR CHARLOTTE-
CITRUS-DESOTO-HARDEE-HERNANDO-HIGHLANDS-HILLSBOROUGH-
LEE-LEVY-MANATEE-PASCO-PINELLAS-POLK-SARASOTA-SUMTER.
HIGH SURF ADVISORY UNTIL 7 PM EST THIS EVENING FOR
CHARLOTTE-HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA.
GULF WATERS...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 10
AM EST SATURDAY FOR ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60
NM-TARPON SPRINGS TO SUWANNEE RIVER OUT 20 TO 60 NM.
GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR ENGLEWOOD
TO TARPON SPRINGS OUT 20 TO 60 NM-TARPON SPRINGS TO
SUWANNEE RIVER OUT 20 TO 60 NM.
SMALL CRAFT ADVISORY UNTIL 10 AM EST SATURDAY FOR BONITA
BEACH TO ENGLEWOOD OUT 20 NM-BONITA BEACH TO
ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON SPRINGS
OUT 20 NM-TAMPA BAY WATERS-TARPON SPRINGS TO SUWANNEE
RIVER OUT 20 NM.
&&
$$
UPDATE/MARINE...MROCZKA
AVIATION...JILLSON
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
548 AM CST FRI DEC 21 2012
.UPDATE...
UPDATED FOR THE 12Z AVIATION DISCUSSION BELOW.
.DISCUSSION...
SINCE THE WORLD HAS NOT ENDED...DOWN TO BUSINESS. THE IMPRESSIVE
SYSTEM THAT BROUGHT INCREDIBLE AMOUNTS OF SNOW AND BLIZZARD
CONDITIONS JUST SOUTH AND EAST OF THE AREA IS STILL SPINNING AWAY
OVER LOWER MICHIGAN. A RIDGE QUICKLY TOOK ITS PLACE ACROSS WRN MN
YESTERDAY AND HAS REMAINED NEARLY STATIONARY SINCE. THE PRESSURE
GRADIENT IS BEGINNING TO RELAX...ESPECIALLY UNDER THE RIDGE WHERE
TEMPERATURES HAVE FALLEN A COUPLE DEGREES BELOW ZERO. FURTHER
EAST...TEENS ABOVE ZERO WERE COMMON EAST OF I-35. SOME WIND CHILL
READINGS WILL APPROACH -20F THIS MORNING NEAR THE SD BORDER WITH
WINDS REMAINING 5 OR 6 KTS.
A BATCH OF STRATUS OVER NWRN MN AND ERN ND HAS BEEN CREEPING SOUTH
OVERNIGHT. RAP FORECAST SOUNDINGS AND RH FIELDS SHOW THIS STRATUS
SPREADING SOUTH ACROSS WEST CENTRAL MN THIS MORNING. CANNOT ARGUE
THIS BASED ON SATELLITE TRENDS AND A STEEP INVERSION ALLOWING THIS
STRATUS TO CONTINUE ADVECTING SWD WITH THE MEAN WIND. NOT SURE HOW
IT WILL EVOLVE THIS AFTERNOON...IT VERY WELL MAY JUST STAY IN
PLACE INTO TONIGHT. FOR NOW...EXTRAPOLATED THAT BANK OF CLOUDS
SOUTH THROUGH THE MORNING WITH A GRADUAL DISSIPATING TREND THIS
AFTERNOON. FLURRIES HAVE ALSO BEEN REPORTED WITH THIS STRATUS
SINCE THE DGZ IS PRACTICALLY AT OR JUST ABOVE THE SURFACE SO ALSO
INCLUDED A CHC OF FLURRIES THROUGH EARLY AFTERNOON WHERE CLOUDS
ARE FORECAST TO BE THICKEST.
OTHERWISE...THE RIDGE WILL REMAIN JUST ABOUT OVERHEAD THROUGH
TONIGHT BEFORE A WEAK COLD FRONT PUSHES SOUTHEAST ACROSS MN AND WI
SATURDAY. DEPENDING ON CLOUD COVER TONIGHT WHICH IS STILL
UNCERTAIN...COULD SEE LOWS TANK IN SOME AREAS. WAS NOT CONFIDENT
TO FORECAST WHERE THIS MAY HAPPEN...SO USED A MODEL BLEND TO
OBTAIN SINGLE DIGITS ABOVE ACROSS THE WHOLE CWA.
THE FRONT WILL COME THROUGH DRY SATURDAY WITH A STRONG SURFACE
RIDGE BUILDING SOUTHEAST FROM WESTERN CANADA. AN UPPER LEVEL
DISTURBANCE WILL SLIDE SOUTHEAST ON THE PERIPHERY OF THE SURFACE
RIDGE MONDAY...BUT A LOT OF DRY AIR SHOULD BE IN PLACE WITH A
NORTHEAST FLOW SO NOT ANTICIPATING MUCH SNOW WITH THIS SYSTEM.
MODELS HAVE ALSO BACKED OFF ON THE AMOUNT OF QPF. REDUCED POPS TO
SCHC...BUT THEY COULD BE TAKEN OUT ALL TOGETHER AT SOME POINT.
THE SURFACE RIDGE WILL NOT REALLY BUDGE NEXT WEEK WITH DRY AND
SEASONABLY COLD WEATHER EXPECTED. A HIGHLY AMPLIFIED UPPER
PATTERN WITH DEEP TROUGHS TRAVERSING THE COUNTRY WILL LARGELY KEEP
THE STORM TRACK WELL TO THE SOUTH. CHRISTMAS EVE AND CHRISTMAS DAY
ARE EXPECTED TO BE QUITE ACTIVE WITH SNOW AND ICE LIKELY ACROSS
THE SOUTHERN PLAINS/MID SOUTH/OHIO VALLEY.
&&
.AVIATION.../12Z TAF ISSUANCE/
ONE LONE ISSUE IS AN AREA OF STRATUS DROPPING SOUTH ACROSS WESTERN
MN. INCLUDED IFR CEILINGS AT KAXN FOR A FEW HOURS LATE THIS
MORNING...BUT THAT SHOULD BE ABOUT THE EXTENT OF THE CLOUDS. HAVE
A LOT OF DOUBT IT WILL MAKE TO EITHER KSTC OR KRWF. THERE WILL BE
A GRADUAL WIND SHIFT TO THE WEST...SOUTHWEST...THEN SOUTH THIS
EVENING.
KMSP...
VFR AT THE AIRPORT TODAY AND TONIGHT. THERE WILL BE A WIND SHIFT
FROM THE CURRENT NORTHWEST DIRECTION TO SOUTHWEST AND EVENTUALLY
SOUTH THIS EVENING AS A HIGH PRESSURE PASSES THROUGH THE AREA. THE
WIND SHIFT WILL OCCUR GRADUALLY AND NO ABRUPT CHANGE IN DIRECTION
IS EXPECTED.
/OUTLOOK FOR KMSP/
SAT...VFR. S 5 KNOTS.
SUN...VFR. NE 5 KNOTS.
MON...VFR...SMALL CHANCE FOR MVFR WITH LIGHT SNOW. NE 5 KNOTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
BB/CLF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
424 AM CST FRI DEC 21 2012
.DISCUSSION...
SINCE THE WORLD HAS NOT ENDED...DOWN TO BUSINESS. THE IMPRESSIVE
SYSTEM THAT BROUGHT INCREDIBLE AMOUNTS OF SNOW AND BLIZZARD
CONDITIONS JUST SOUTH AND EAST OF THE AREA IS STILL SPINNING AWAY
OVER LOWER MICHIGAN. A RIDGE QUICKLY TOOK ITS PLACE ACROSS WRN MN
YESTERDAY AND HAS REMAINED NEARLY STATIONARY SINCE. THE PRESSURE
GRADIENT IS BEGINNING TO RELAX...ESPECIALLY UNDER THE RIDGE WHERE
TEMPERATURES HAVE FALLEN A COUPLE DEGREES BELOW ZERO. FURTHER
EAST...TEENS ABOVE ZERO WERE COMMON EAST OF I-35. SOME WIND CHILL
READINGS WILL APPROACH -20F THIS MORNING NEAR THE SD BORDER WITH
WINDS REMAINING 5 OR 6 KTS.
A BATCH OF STRATUS OVER NWRN MN AND ERN ND HAS BEEN CREEPING SOUTH
OVERNIGHT. RAP FORECAST SOUNDINGS AND RH FIELDS SHOW THIS STRATUS
SPREADING SOUTH ACROSS WEST CENTRAL MN THIS MORNING. CANNOT ARGUE
THIS BASED ON SATELLITE TRENDS AND A STEEP INVERSION ALLOWING THIS
STRATUS TO CONTINUE ADVECTING SWD WITH THE MEAN WIND. NOT SURE HOW
IT WILL EVOLVE THIS AFTERNOON...IT VERY WELL MAY JUST STAY IN
PLACE INTO TONIGHT. FOR NOW...EXTRAPOLATED THAT BANK OF CLOUDS
SOUTH THROUGH THE MORNING WITH A GRADUAL DISSIPATING TREND THIS
AFTERNOON. FLURRIES HAVE ALSO BEEN REPORTED WITH THIS STRATUS
SINCE THE DGZ IS PRACTICALLY AT OR JUST ABOVE THE SURFACE SO ALSO
INCLUDED A CHC OF FLURRIES THROUGH EARLY AFTERNOON WHERE CLOUDS
ARE FORECAST TO BE THICKEST.
OTHERWISE...THE RIDGE WILL REMAIN JUST ABOUT OVERHEAD THROUGH
TONIGHT BEFORE A WEAK COLD FRONT PUSHES SOUTHEAST ACROSS MN AND WI
SATURDAY. DEPENDING ON CLOUD COVER TONIGHT WHICH IS STILL
UNCERTAIN...COULD SEE LOWS TANK IN SOME AREAS. WAS NOT CONFIDENT
TO FORECAST WHERE THIS MAY HAPPEN...SO USED A MODEL BLEND TO
OBTAIN SINGLE DIGITS ABOVE ACROSS THE WHOLE CWA.
THE FRONT WILL COME THROUGH DRY SATURDAY WITH A STRONG SURFACE
RIDGE BUILDING SOUTHEAST FROM WESTERN CANADA. AN UPPER LEVEL
DISTURBANCE WILL SLIDE SOUTHEAST ON THE PERIPHERY OF THE SURFACE
RIDGE MONDAY...BUT A LOT OF DRY AIR SHOULD BE IN PLACE WITH A
NORTHEAST FLOW SO NOT ANTICIPATING MUCH SNOW WITH THIS SYSTEM.
MODELS HAVE ALSO BACKED OFF ON THE AMOUNT OF QPF. REDUCED POPS TO
SCHC...BUT THEY COULD BE TAKEN OUT ALL TOGETHER AT SOME POINT.
THE SURFACE RIDGE WILL NOT REALLY BUDGE NEXT WEEK WITH DRY AND
SEASONABLY COLD WEATHER EXPECTED. A HIGHLY AMPLIFIED UPPER
PATTERN WITH DEEP TROUGHS TRAVERSING THE COUNTRY WILL LARGELY KEEP
THE STORM TRACK WELL TO THE SOUTH. CHRISTMAS EVE AND CHRISTMAS DAY
ARE EXPECTED TO BE QUITE ACTIVE WITH SNOW AND ICE LIKELY ACROSS
THE SOUTHERN PLAINS/MID SOUTH/OHIO VALLEY.
&&
.AVIATION... /06Z TAF ISSUANCE/
AREAS OF LOW END MVFR TO IFR CEILINGS REMAIN OVER THE AREA THIS
EVENING. FARTHER TO THE NORTHWEST AREA OF LOW LEVEL MOISTURE
REMAINS TRAPPED UNDER SUBSIDENCE INVERSION LOCATED BENEATH THE
SURFACE RIDGE OVER THE EASTERN DAKOTAS. SOME EXPANSION TO THE
SOUTH NOTED WITH THIS AREA. FURTHER WEST...SOME ICE FOG DEVELOPING
OVER EASTERN SOUTH DAKOTA. NEW NAM AND LATEST HRRR SHOWING SOME
POSSIBILITY OF LOWER CLOUDS AND ICE FOG DEVELOPING UNDER THE
RIDGE...BUT APPEARS BEST CHANCE WILL REMAIN OVER THE EASTERN
DAKOTAS. THE IFR CEILINGS AT KRWF REMAIN ASSOCIATED WITH ELEVATED
SNOW LAYER ALONG THE MN RIVER VALLEY DUE TO EARLIER BLSN. THIS WILL
GRADUALLY DISSIPATE AFTER 06Z AS WIND SUBSIDES. WILL HAVE TO HOLD
ONTO THE POSSIBILITY OF SOME LOW END MVFR CEILING FARTHER EAST INTO
WISCONSIN IN THE WAKE OF THE STORM...AS NARRE-TL INDICATED SOME HIGH
PROBABILITIES FOR THIS OCCURRING. SHOULD SEE SKC/VFR DEVELOPING INTO THE
MORNING FRIDAY...LASTING THROUGH FRIDAY NIGHT.
GUSTY NORTHWEST WINDS WILL DIMINISH OVER THE EASTERN AREAS LATER
TONIGHT/FRIDAY MORNING AND SURFACE WINDS WILL EVENTUALLY TURN
SOUTHERLY LATE FRIDAY AFTERNOON OVER THE WEST AS THE HIGH PRESSURE
RIDGE MOVES THROUGH.
KMSP...CONFIDENCE NOT HIGH ON VFR CONDITIONS REMAINING THROUGH THE
NIGHT. STILL SEE SOME BKN-OVC010-015 NORTHWEST OF THE AREA AND STILL
MAY WORK TO THE SOUTHEAST THROUGH THE EARLY MORNING. WILL HOLD ONTO
SOME FEW-SCT013 OVERNIGHT ANYWAY. SHOULD SEE VFR THEN DEVELOPING
FRIDAY MORNING LASTING FRIDAY NIGHT AS THE HIGH MOVES THROUGH.
NORTHWEST WINDS DIMINISHING OVERNIGHT AND THEN BECOMING MORE
SOUTHWEST LATE AFTERNOON AND SOUTHERLY AFTER 00Z SAT.
/OUTLOOK FOR KMSP/
FRI...VFR. NW 5 TO 10 KNOTS.
SAT...VFR. S 5 KNOTS.
SUN...VFR. NE 5 KNOTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
BORGHOFF/DWE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
531 AM CST FRI DEC 21 2012
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
240 AM CST FRI DEC 21 2012
MAIN FORECAST CONCERNS TO BEGIN THE FIRST DAY OF WINTER ARE ON
TEMPERATURES TONIGHT...ANY LOW CLOUD POTENTIAL SATURDAY NIGHT INTO
SUNDAY...AND ANY PRECIPITATION POTENTIAL SUNDAY NIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED DEEP TROUGHING OFF THE WEST COAST OF THE U.S....RIDGING
BUILDING ALONG THE LEE OF THE ROCKIES INTO SOUTH CENTRAL CANADA...
AND DEEP TROUGHING FROM THE GREAT LAKES INTO THE SOUTHEASTERN U.S..
THE LATTER DEEP TROUGHING CONTAINS THE STRONG STORM SYSTEM THAT
BROUGHT THE SNOW AND STRONG WINDS TO THE FORECAST AREA YESTERDAY.
ROADS STILL REMAIN HAZARDOUS TOO...ESPECIALLY OVER THE SOUTHEASTERN
PORTION OF THE FORECAST AREA. WINDS REMAIN BRISK...DUE TO A TIGHT
PRESSURE GRADIENT BETWEEN 987MB LOW PRESSURE NEAR DETROIT AND A
1025MB HIGH PRESSURE RIDGE OVER THE EASTERN DAKOTAS. WITH THE
FORECAST AREA EXPERIENCING RISING HEIGHTS AT 500MB...ABOUT 40 METERS
SINCE 00Z ACCORDING TO THE RAP...SUBSIDENCE HAS BEEN ON THE
INCREASE. DRY ADVECTION WAS ALSO OCCURRING...NOTED BY THE
PRECIPITABLE WATER DROPPING AT MPX FROM 0.33 INCHES AT 12Z ON THE
20TH TO 0.16 INCHES AT 00Z. THE COMBINATION OF SUBSIDENCE AND DRYING
HAS LED TO CLEARING SKIES IN THE WAKE OF THE STORM SYSTEM. CLEARING
LINE STRETCHED FROM EAU CLAIRE TO LA CROSSE AND DUBUQUE. COLDER AIR
ALSO ACCOMPANYING THE SUBSIDENCE AND DRYING...REFLECTED BY SURFACE
TEMPERATURES IN THE SINGLE DIGITS ACROSS WESTERN PORTIONS OF
MINNESOTA AND IOWA...AND IN THE SINGLE DIGITS BELOW ZERO OVER THE
EASTERN DAKOTAS UNDER THE SURFACE RIDGE. 925MB TEMPS AT MPX AT 00Z
WERE -10C...ABOUT 3 COLDER THAN 12 HOURS EARLIER.
TODAY AND TONIGHT...THE UPPER RIDGING ALONG THE LEE OF THE ROCKIES
WILL SHIFT EASTWARD INTO THE PLAINS BY TONIGHT IN RESPONSE TO THE
DEEP EAST PACIFIC TROUGH APPROACHING THE WESTERN U.S. COAST. WITH
THE UPPER RIDGING TRYING TO PUSH INTO THE FORECAST AREA...MID LEVEL
HEIGHTS WILL CONTINUE TO CLIMB...MAINTAINING THE SUBSIDENCE. IN
ADDITION...THE SHIFT EAST IN THE UPPER PATTERN OCCURS AT THE SURFACE
AS WELL...WITH THE HIGH PRESSURE RIDGE SHIFTING EAST OVER THE
FORECAST AREA AROUND MIDNIGHT. WITH THE SUBSIDENCE AND DRYING
PATTERN IN PLACE...EXPECT A DRY PERIOD. IN FACT...OTHER THAN A FEW
HIGH CLOUDS AFTER MIDNIGHT TONIGHT CROSSING THE UPPER RIDGE...SKIES
SHOULD BE MAINLY CLEAR. DESPITE THE PLENTIFUL SUNSHINE TODAY...
BREEZY NORTHWEST WINDS COMBINED WITH 925MB TEMPS IN THE -6 TO -10C
RANGE AND FRESH SNOW COVER WILL LIMIT HEATING. HIGHS SHOULD TOP OUT
FROM THE MID TEENS TO MID 20S...COLDEST OVER THE HIGHER ALBEDO
PRESENT WEST OF THE MISSISSIPPI RIVER. CONCERN FOR TEMPERATURES
PLUMMETING TONIGHT GIVEN THE COOLER DAY TODAY...DECOUPLING WINDS AND
MOSTLY CLEAR SKIES. HAVE LEANED TOWARDS THE COLD SIDE OF GUIDANCE AS
A RESULT.
SATURDAY AND SATURDAY NIGHT...MODELS ARE POINTING TO A SHORTWAVE
CURRENTLY IN SOUTHEAST BRITISH COLUMBIA TOPPING THE RIDGE AND MOVING
THROUGH EASTERN LAKE SUPERIOR SATURDAY NIGHT. ALTHOUGH THIS
SHORTWAVE IS FAR FROM US...A COLD FRONT ACCOMPANIES THE SHORTWAVE
WHICH SLIDES THROUGH THE FORECAST AREA SATURDAY NIGHT. AHEAD OF THE
FRONT...WE SEE SOME 925MB WARMING...PROGGED TO CLIMB TO -2C OR SO
BY 18Z SATURDAY. 850MB TEMPS ARE EVEN WARMER...0-3C OR SO...BUT
THERE IS NO WAY OF MIXING UP TO THIS DUE TO BEING NOW AT THE
SHORTEST DAY LENGTH AND HAVING THE FRESH SNOW. NEVERTHELESS...
COMBINATION OF SUN THROUGH SOME HIGH CLOUDS AND SOUTHWEST WINDS
PICKING UP A BIT SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE 20S
EVERYWHERE. SOME VALLEY LOCATIONS COULD PUSH 30. NOT ANTICIPATING
ANY PRECIPITATION TO ACCOMPANY THE FRONTAL PASSAGE...DUE TO
PLENTIFUL DRY AIR AND ALL FORCING WELL NORTHEAST OF THE AREA.
HOWEVER...AFTER THE FRONTAL PASSAGE...CONCERNED THERE MAY BE AN
INCREASE OF LOW CLOUDS AS SUGGESTED BY 21.00Z GFS 925MB RH FIELDS.
THE 21.00Z NAM AND ECMWF 925MB RH FIELD ARE NOT NEARLY AS
PESSIMISTIC AND THUS WILL CONTINUE WITH THE PREVIOUS MOSTLY CLEAR
FORECAST. COMBINATION OF COLD ADVECTION IN THE WAKE OF THE FRONT AND
RADIATIONAL COOLING ARE EXPECTED TO SEND TEMPERATURES BACK DOWN INTO
THE SINGLE DIGITS AND TEENS.
SUNDAY AND SUNDAY NIGHT...SOME OF THE CURRENT EASTERN PACIFIC TROUGH
IS PROGGED BY ALL MODELS TO HEAD EAST INTO THE PLAINS SUNDAY NIGHT.
ASSOCIATED WITH THIS UPPER TROUGHING IS A NORTHWEST TO SOUTHEAST
ORIENTED INVERTED TROUGH AT THE SURFACE...WHICH BY 12Z MONDAY SHOULD
HAVE REACHED AT LEAST SIOUX FALLS PER MODEL CONSENSUS. GIVEN THE
APPROACH OF THE UPPER AND INVERTED SURFACE TROUGH...ONE WOULD EXPECT
AN ISENTROPIC LIFT PATTERN...WHICH INDEED EXISTS. HOWEVER...ANY
ISENTROPIC LIFT IS ROOTED ON THE 290-300K SURFACES WHICH PUTS IT AT
A PRESSURE LEVEL OF 700MB OR HIGHER...AND MORE TOWARDS 12Z.
THEREFORE...NOT SURE IF ANY PRECIPITATION CAN MAKE IT TO THE
SURFACE. THE 21.00Z NAM/GFS ARE BOTH DRY FOR SUNDAY NIGHT. AS
SUCH...HAVE KEPT A DRY FORECAST GOING. LOW CLOUD COVER CONCERN STILL
EXISTS HERE FOR SUNDAY AND SUNDAY NIGHT...ESPECIALLY IF SOME MOVE IN
BEHIND THE SATURDAY NIGHT COLD FRONT. SHOULD LOW CLOUDS MOVE
IN...LIKELY SUNDAY AND SUNDAY NIGHT WILL END UP CLOUDY. CLOUDS ARE
GOING TO INCREASE ANYWAY...ESPECIALLY SUNDAY NIGHT ASSOCIATED WITH
THE ISENTROPIC LIFT REGIME AHEAD OF THE UPPER TROUGH. GIVEN THE
UNCERTAINTY SURROUNDING CLOUD COVER ON SUNDAY...WENT WITH A BLEND OF
GUIDANCE FOR HIGHS. THE BLEND OF GUIDANCE LOOKS GOOD TOO FOR LOWS
SUNDAY NIGHT AS IT HANDLES THE CLOUD COVER INCREASE FINE.
.LONG TERM...MONDAY THROUGH THURSDAY
240 AM CST FRI DEC 21 2012
21.00Z ECMWF/GFS/CANADIAN/UKMET ARE IN FAIRLY GOOD AGREEMENT BOTH
WITH THE UPPER AND SURFACE PATTERNS THROUGHOUT THE LONG TERM PERIOD.
MAIN STORM TRACK THROUGHOUT THE LONG TERM IS SOUTH OF THE FORECAST
AREA...WHERE THERE APPEARS TO BE A STORM SYSTEM THAT CROSSES THE
SOUTHERN PLAINS INTO THE MID-ATLANTIC REGION INTO NEW ENGLAND
BETWEEN TUESDAY THROUGH THURSDAY. TRENDS CONTINUE SOUTH WITH THIS
SYSTEM...THUS ALL PRECIPITATION STAYS AWAY FROM THE FORECAST AREA.
THE ONLY SYSTEM REALLY TO DEAL WITH IS THAT UPPER TROUGH AND
INVERTED TROUGH APPROACHING THE FORECAST AREA SUNDAY NIGHT. MODELS
SUGGEST THE UPPER TROUGH IS ACTUALLY SPLIT INTO TWO PARTS...WITH THE
MAIN FEATURE/SHORTWAVE IN IT TRACKING ACROSS THE OHIO RIVER VALLEY.
WE HAVE THE NORTHERN PART OF THE TROUGH CROSSING THE FORECAST
AREA MONDAY INTO MONDAY NIGHT...BUT ALL THE BETTER MOISTURE IS WITH
THE SOUTHERN SHORTWAVE. THE 21.00Z ECMWF BASICALLY CAME IN DRY WITH
THE NORTHERN PART OF THE TROUGH AND THE 21.00Z GFS ONLY HAS SOME
VERY LIGHT QPF. GIVEN THE LACK OF MOISTURE...ESPECIALLY BELOW
700MB...ONLY HAVE 20 PERCENT CHANCES OF PRECIPITATION IN THE
FORECAST FOR MONDAY AND MONDAY NIGHT. IF TRENDS CONTINUE...THESE
COULD BE PULLED IN LATER FORECASTS.
WITH A STORM TRACK MORE TO THE SOUTH OF THE FORECAST AREA...THIS
MEANS NO WARM UPS ARE IN STORE. IN FACT...THE BULK OF THE PERIOD
SHOULD AVERAGE BELOW NORMAL AS 925MB TEMPS COOL TO -10 TO -12C FOR
TUESDAY AND WEDNESDAY BEHIND THE INVERTED TROUGH. SOME SLIGHT
WARMING SHOULD OCCUR FOR THURSDAY. SOMETHING TO WATCH IS IF WE END
UP WITH CLEAR SKIES AND LIGHT WINDS AT NIGHT...SINCE SNOW COVER IS
VERY FAVORABLE FOR HAVING TEMPERATURES PLUMMET.
&&
.AVIATION...TODAY AND TONIGHT
531 AM CST FRI DEC 21 2012
GUSTY NORTHWEST WINDS WILL CONTINUE THROUGH THIS MORNING...THEN
SLOWLY SUBSIDE THIS AFTERNOON. OTHERWISE...MOSTLY CLEAR/VFR CONDITIONS
EXPECTED AT KRST/KLSE TAF SITES THROUGH TONIGHT AS A RIDGE OF HIGH
PRESSURE DRIFTS ACROSS THE UPPER MISSISSIPPI RIVER REGION.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
240 AM CST FRI DEC 21 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...DAS
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
210 PM EST FRI DEC 21 2012
...A WINTER FEEL TO THE FORECAST THE NEXT COUPLE OF DAYS...
.SYNOPSIS...
18Z WATER VAPOR AND H4 RAP ANALYSIS CONTINUES TO SHOW A HIGHLY
AMPLIFIED UPPER LEVEL PATTERN OVER THE CONUS. PATTERN CONSISTS OF
TROUGHING BEGINNING TO MOVE ASHORE ALONG THE PACIFIC COASTLINE
FOLLOWED DOWNSTREAM BY LONGWAVE RIDGING ACROSS THE INTERMOUNTAIN
WEST AND HIGH PLAINS. THE FLOW THE SHARPLY DIPS BACK TO THE SOUTH
INTO AND IMPRESSIVE NEGATIVELY TILTED TROUGH AND CLOSED LOW FEATURE
COVERING THE EASTERN THIRD OF THE NATION. ASSOCIATED WITH THIS
PARENT ENERGY WE FIND STRONG 982MB SURFACE LOW PRESSURE OVER THE
NORTHEASTERN STATES WITH A COLD FRONT TRAILING OFF THE ATLANTIC
SEABOARD ALL THE WAY DOWN THROUGH THE BAHAMAS AND CUBA.
THIS COLD FRONT RAPIDLY PUSHED ACROSS OUR FORECAST AREA LAST NIGHT
WITH A NARROW BAND OF CONVECTION. THAT RAINFALL IS LONG GONE AS A
MUCH COLDER AND DRIER AIRMASS CONTINUES TO ARRIVE ON GUSTY NORTHWEST
WINDS. HIGH PRESSURE IS SLOWLY BUILDING EASTWARD ALONG THE NORTHERN
GULF COAST THIS AFTERNOON AND WILL BE SETTLING OVER THE REGION
DURING THE UPCOMING WEEKEND. THE STRONG NW WINDS UP TO 30 KNOTS IS
PUSHING A DECENT SWELL TOWARD THE COAST AND SURF HEIGHTS AT AREA
BEACHES HAVE REACHED 4-6 FEET PROMPTING A HIGH SURF ADVISORY THROUGH
TONIGHT. THE RIP CURRENT RISK IS ALSO HIGH AS A RESULT OF THIS SURF.
&&
.SHORT TERM (TONIGHT THROUGH SUNDAY NIGHT)...
TONIGHT...A COLD/CHILLY NIGHT ON TAP. HIGH PRESSURE WILL STILL BE
CENTERED WELL TO OUR WEST. THERE IS A RIDGE AXIS THAT EXTENDS OVER
TOWARD US...BUT THE GRADIENT WILL NOT RELAX ENOUGH OVER MUCH OF THE
AREA TO ALLOW FOR MUCH OF A RADIATIVE COMPONENT TO THE TEMPERATURE
DROP. WILL BE LOOKING AT MORE OF AN ADVECTION DROP IN TEMPS WITH
SOME COLD AIR DRAINAGE FROM THE NORTH DOWN THE PENINSULA. CURRENT
FORECAST IS LOOKING FOR WIDESPREAD LOWER TO MIDDLE 30S AWAY FROM THE
IMMEDIATE COAST...AND EVEN COLDER (MID 20S TO AROUND 30) OVER THE
INTERIOR NATURE COAST ZONES. A FREEZE WARNING REMAINS IN EFFECT FOR
THE NATURE COAST ZONES LATE TONIGHT INTO EARLY SATURDAY MORNING FOR
SEVERAL HOURS OF SUB-FREEZING TEMPS. ALTHOUGH A FREEZE WARNING IS
NOT CURRENTLY IN EFFECT FURTHER SOUTH...TEMPERATURES MAY BRIEFLY
APPROACH 32 IN SPOTS. DEWPOINT DEPRESSIONS LATE TONIGHT ARE 6-10C
WHICH ALONG WITH A LIGHT WIND SHOULD PREVENT ANY SIGNIFICANT FROST
FORMATION. AN APPROACHING UPPER LEVEL JET FROM THE NORTHWEST WILL
LIKELY BRING IN SOME THIN HIGH CLOUDS FROM THE WEST DURING THE
OVERNIGHT...HOWEVER WITH THIS NOT BEING A RADIATIONAL COOLING
EVENT...THESE HIGH CLOUDS SHOULD HAVE LITTLE IMPACT ON THE TEMP
FORECAST. THE COMBINATION OF LOW TEMPERATURES AND AT LEAST SOME WIND
STAYING UP OVERNIGHT HAS PROMPTED THE ISSUANCE OF A WIND CHILL
ADVISORY FOR ALL OF THE FORECAST AREA. THE ADVISORY CRITERIA ARE
MOST LIKELY TO BE MET AFTER MIDNIGHT INTO THE FIRST 1-2 DAYLIGHT
HOURS OF SATURDAY. STAY WARM...AND WELCOME TO OFFICIAL WINTER.
SATURDAY/SATURDAY NIGHT...
SURFACE HIGH PRESSURE CONTINUES TO BUILD EASTWARD TOWARD THE AREA
AND WILL BE DIRECTLY OVERHEAD BY SATURDAY NIGHT. SATURDAY WILL BE
ANOTHER FAIR...DRY...AND SEASONABLY COOL DAY AS TEMPERATURES
STRUGGLE INTO THE LOWER 60S NORTH AND MIDDLE 60S SOUTH. SATURDAY
EVENING AS THE SUN GOES DOWN...EXPECTING TEMPERATURES TO DROP
QUICKLY AS LIGHT WINDS AND A DRY COLUMN PROMOTE EXCELLENT
RADIATIONAL COOLING CONDITIONS. THE FREEZE WATCH REMAIN IN EFFECT
FOR THE NATURE COAST ZONES FOR SEVERAL HOURS AFTER MIDNIGHT OF
SUB-FREEZING TEMPS. CONSIDERED EXPANDING THE WATCH FURTHER
SOUTH...BUT THERE IS SOME CONCERN ABOUT THE IMPACTS OF SOME HIGHER
MOISTURE/CIRRUS MOVING IN FROM THE WEST DURING THE SECOND HALF OF
THE NIGHT. SOMETIMES THIS TYPE OF MOISTURE ADVECTION CAN HAVE THE
IMPACT OF SLOWLY THE RADIATIVE PROCESS. THIS UNCERTAINLY IN THE
DEPTH AND EXACT TIMING MAKES THE LOW TEMPERATURE FORECAST DIFFICULT.
IF THE CIRRUS HOLD OFF UNTIL DAWN...THEN TEMPS MAY BE A BIT
COOLER...BUT IF IF MOVES IN DURING THE PRE-DAWN HOURS...THEN THE
CURRENT GRIDS MIGHT BE TOO COLD. FOR NOW WILL EXPECT TO SEE GET A
FEW HOURS OF FREEZING NORTH OF I-4 AND GET TO NEAR FREEZING AWAY
FROM THE COAST FURTHER SOUTH. SMALLER DEWPOINT DEPRESSION WILL MAKE
FROST FORMATION MORE LIKELY FOR ALL AREAS DROPPING INTO THE MIDDLE
30S OR LOWER.
SUNDAY/SUNDAY NIGHT...
HIGH PRESSURE MOVES OFF TO OUR EAST WITH WINDS SLOWLY COMING AROUND
TO THE SOUTHEAST AND SOUTH WITH TIME. TEMPERATURES WILL BEGIN A
WARMING TREND BETWEEN THIS HIGH AND A COLD FRONT WELL OFF TO OUR
WEST. AT THIS TIME...NO FREEZING TEMPERATURES ARE EXPECTED SUNDAY
NIGHT.
&&
.LONG TERM (SUNDAY NIGHT-THURSDAY)...
U/L PATTERN WILL BEGIN WITH ZONAL FLOW ACROSS THE U.S. WITH A WEAK
DISTURBANCE MOVING THROUGH THE OHIO RIVER VALLEY MONDAY WITH AN
ASSOCIATED COLD FRONT DROPPING OVER THE SOUTHEAST U.S. AS THE FRONT
BECOMES PARALLEL TO THE U/L FLOW IT WILL STALL ACROSS NORTH FLORIDA
MONDAY NIGHT. A STRONG U/L DISTURBANCE WILL DIG THROUGH THE
SOUTHERN PLAINS TUESDAY WHICH WILL ENHANCE SHOWERS AND THUNDERSTORMS
ALONG THE STALLED FRONT ACROSS THE GULF COAST AND SOUTHEAST U.S.
SURFACE HIGH PRESSURE WILL PUSH EAST OF FLORIDA WITH INCREASING
SOUTHERLY FLOW AND LOW LEVEL MOISTURE ADVECTING OVER WEST CENTRAL
AND SOUTHWEST FLORIDA IN THE WARM SECTOR SOUTH OF THE FRONTAL
BOUNDARY. AN AREA OF LOW PRESSURE WILL DEVELOP OVER THE LOWER
MISSISSIPPI VALLEY AND INTENSIFY AS IT MOVES NORTHEAST TUESDAY
NIGHT. A STRONG COLD FRONT WILL MOVE ACROSS WEST CENTRAL AND
SOUTHWEST FLORIDA WEDNESDAY...HOWEVER U/L SUPPORT WILL BE LIFTING
RAPIDLY NORTH OF THE REGION. BAND OF SHOWERS AND POSSIBLE
THUNDERSTORMS WILL PUSH ACROSS THE FORECAST AREA BUT ACTIVITY WILL
WEAKEN THROUGH THE DAY. SURFACE HIGH PRESSURE WILL BUILD OVER THE
FORECAST AREA BEHIND THE FRONT WEDNESDAY NIGHT AND THURSDAY WITH
GUSTY NORTHWEST WINDS ADVECTING DRIER COOLER AIR ACROSS THE
AREA.
&&
.AVIATION...
WINDS SHOULD BECOME LESS GUSTY FROM THE NORTH-NORTHWEST TONIGHT THEN
NORTHERLY AT 9 TO 13 KNOTS ON SATURDAY. NO CEILING/VISIBILITY
RESTRICTIONS.
&&
.MARINE...
ADVISORY LEVEL CONDITIONS ARE ONGOING ACROSS THE EASTERN GULF OF
MEXICO. ANY GALE FORCE GUSTS SHOULD END BY EARLY EVENING...HOWEVER
ADVISORY CRITERIA WINDS AND SEAS WILL PERSIST THROUGH LATE TONIGHT
OR EARLY SATURDAY. THE HIGH WILL MOVE ACROSS THE REGION DURING THE
WEEKEND AND ALLOW WINDS AND SEAS TO SUBSIDE. THE NEXT COLD FRONT IS
ANTICIPATED DURING EARLY TO MID NEXT WEEK.
&&
.FIRE WEATHER...
VERY DRY AIR AND GUSTY NORTHWESTERLY WINDS ARE RESULTING IN RED FLAG
CONDITIONS THIS AFTERNOON. TEMPERATURES WILL BEGIN TO DROP RAPIDLY
TOWARD SUNSET ALLOWING WINDS TO DIMINISH AND HUMIDITIES TO RISE. IT
WILL BE VERY DRY AGAIN ON SATURDAY AND SUNDAY BUT WINDS WILL BE
LIGHTER WHICH SHOULD PRECLUDE RED FLAG CONDITIONS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 40 63 40 66 / 0 0 0 0
FMY 41 66 40 71 / 0 0 0 0
GIF 34 63 33 68 / 0 0 0 0
SRQ 43 63 40 66 / 0 0 0 0
BKV 30 62 28 67 / 0 0 0 0
SPG 45 62 48 66 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY
MORNING FOR CITRUS-HERNANDO-LEVY-PASCO-SUMTER.
RED FLAG WARNING UNTIL 6 PM EST THIS EVENING FOR CHARLOTTE-
CITRUS-DESOTO-HARDEE-HERNANDO-HIGHLANDS-HILLSBOROUGH-
LEE-LEVY-MANATEE-PASCO-PINELLAS-POLK-SARASOTA-SUMTER.
FREEZE WARNING FROM 2 AM TO 9 AM EST SATURDAY FOR CITRUS-
HERNANDO-LEVY-PASCO-SUMTER.
LAKE WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR
CHARLOTTE-CITRUS-DESOTO-HARDEE-HERNANDO-HIGHLANDS-
HILLSBOROUGH-LEE-LEVY-MANATEE-PASCO-PINELLAS-POLK-
SARASOTA-SUMTER.
WIND CHILL ADVISORY FROM 11 PM THIS EVENING TO 9 AM EST
SATURDAY FOR CHARLOTTE-CITRUS-DESOTO-HARDEE-HERNANDO-
HIGHLANDS-HILLSBOROUGH-LEE-LEVY-MANATEE-PASCO-
PINELLAS-POLK-SARASOTA-SUMTER.
HIGH SURF ADVISORY UNTIL 7 AM EST SATURDAY FOR CHARLOTTE-
HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA.
GULF WATERS...SMALL CRAFT ADVISORY UNTIL 10 AM EST SATURDAY FOR BONITA
BEACH TO ENGLEWOOD OUT 20 NM-BONITA BEACH TO
ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON SPRINGS
OUT 20 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM-
TAMPA BAY WATERS-TARPON SPRINGS TO SUWANNEE RIVER OUT
20 NM-TARPON SPRINGS TO SUWANNEE RIVER OUT 20 TO 60
NM.
&&
$$
SYNOPSIS/SHORT TERM/MARINE...MROCZKA
AVIATION/FIRE WX...JILLSON
LONG TERM...OGLESBY
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1155 AM CST FRI DEC 21 2012
.UPDATE...
18Z AVIATION DISCUSSION ADDED BELOW.
&&
.DISCUSSION...
/ISSUED 424 AM CST FRI DEC 21 2012/
SINCE THE WORLD HAS NOT ENDED...DOWN TO BUSINESS. THE IMPRESSIVE
SYSTEM THAT BROUGHT INCREDIBLE AMOUNTS OF SNOW AND BLIZZARD
CONDITIONS JUST SOUTH AND EAST OF THE AREA IS STILL SPINNING AWAY
OVER LOWER MICHIGAN. A RIDGE QUICKLY TOOK ITS PLACE ACROSS WRN MN
YESTERDAY AND HAS REMAINED NEARLY STATIONARY SINCE. THE PRESSURE
GRADIENT IS BEGINNING TO RELAX...ESPECIALLY UNDER THE RIDGE WHERE
TEMPERATURES HAVE FALLEN A COUPLE DEGREES BELOW ZERO. FURTHER
EAST...TEENS ABOVE ZERO WERE COMMON EAST OF I-35. SOME WIND CHILL
READINGS WILL APPROACH -20F THIS MORNING NEAR THE SD BORDER WITH
WINDS REMAINING 5 OR 6 KTS.
A BATCH OF STRATUS OVER NWRN MN AND ERN ND HAS BEEN CREEPING SOUTH
OVERNIGHT. RAP FORECAST SOUNDINGS AND RH FIELDS SHOW THIS STRATUS
SPREADING SOUTH ACROSS WEST CENTRAL MN THIS MORNING. CANNOT ARGUE
THIS BASED ON SATELLITE TRENDS AND A STEEP INVERSION ALLOWING THIS
STRATUS TO CONTINUE ADVECTING SWD WITH THE MEAN WIND. NOT SURE HOW
IT WILL EVOLVE THIS AFTERNOON...IT VERY WELL MAY JUST STAY IN
PLACE INTO TONIGHT. FOR NOW...EXTRAPOLATED THAT BANK OF CLOUDS
SOUTH THROUGH THE MORNING WITH A GRADUAL DISSIPATING TREND THIS
AFTERNOON. FLURRIES HAVE ALSO BEEN REPORTED WITH THIS STRATUS
SINCE THE DGZ IS PRACTICALLY AT OR JUST ABOVE THE SURFACE SO ALSO
INCLUDED A CHC OF FLURRIES THROUGH EARLY AFTERNOON WHERE CLOUDS
ARE FORECAST TO BE THICKEST.
OTHERWISE...THE RIDGE WILL REMAIN JUST ABOUT OVERHEAD THROUGH
TONIGHT BEFORE A WEAK COLD FRONT PUSHES SOUTHEAST ACROSS MN AND WI
SATURDAY. DEPENDING ON CLOUD COVER TONIGHT WHICH IS STILL
UNCERTAIN...COULD SEE LOWS TANK IN SOME AREAS. WAS NOT CONFIDENT
TO FORECAST WHERE THIS MAY HAPPEN...SO USED A MODEL BLEND TO
OBTAIN SINGLE DIGITS ABOVE ACROSS THE WHOLE CWA.
THE FRONT WILL COME THROUGH DRY SATURDAY WITH A STRONG SURFACE
RIDGE BUILDING SOUTHEAST FROM WESTERN CANADA. AN UPPER LEVEL
DISTURBANCE WILL SLIDE SOUTHEAST ON THE PERIPHERY OF THE SURFACE
RIDGE MONDAY...BUT A LOT OF DRY AIR SHOULD BE IN PLACE WITH A
NORTHEAST FLOW SO NOT ANTICIPATING MUCH SNOW WITH THIS SYSTEM.
MODELS HAVE ALSO BACKED OFF ON THE AMOUNT OF QPF. REDUCED POPS TO
SCHC...BUT THEY COULD BE TAKEN OUT ALL TOGETHER AT SOME POINT.
THE SURFACE RIDGE WILL NOT REALLY BUDGE NEXT WEEK WITH DRY AND
SEASONABLY COLD WEATHER EXPECTED. A HIGHLY AMPLIFIED UPPER
PATTERN WITH DEEP TROUGHS TRAVERSING THE COUNTRY WILL LARGELY KEEP
THE STORM TRACK WELL TO THE SOUTH. CHRISTMAS EVE AND CHRISTMAS DAY
ARE EXPECTED TO BE QUITE ACTIVE WITH SNOW AND ICE LIKELY ACROSS
THE SOUTHERN PLAINS/MID SOUTH/OHIO VALLEY.
&&
.AVIATION.../18Z TAF ISSUANCE/
FEW WEATHER CONCERNS THIS TAF PERIOD AS HIGH PRESSURE SLOWLY WORKS
ACROSS THE AREA THROUGH TONIGHT. TOWARD THE END OF THE PERIOD...A
WEAK COLD WILL BE APPROACHING CENTRAL MN...WHICH WILL HELP FORCE
WINDS OVER TO THE SOUTH OVERNIGHT. SPEEDS WILL BE UNDER 10 KTS
WITH CLOUD COVER BEING NOTHING MORE THAN VARYING AMOUNTS OF
CIRRUS.
KMSP...HIGH CONFIDENCE TAF OVERALL. SHOULD BE GOOD TO HOLD A 30/35
OPERATION THROUGH THE REST OF THE DAY...WITH WINDS SATURDAY COMING
OUT OF THE SOUTH...THOUGH UNDER 7 KTS.
/OUTLOOK FOR KMSP/
SUN...IFR CIGS POSSIBLE EARLY...OTHERWISE VFR. WINDS NE 5 KTS.
MON...VFR...SMALL CHANCE FOR MVFR WITH LIGHT SNOW. NE 5 KNOTS.
TUE...VFR. WINDS N 5 TO 10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
BORGHOFF/MPG
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1011 AM CST FRI DEC 21 2012
.DISCUSSION...CLOUDS AND CLEARING TRENDS CONTINUE TO BE A
CHALLENGE. 16Z SATELLITE IMAGERY INDICATES A CLEAR AREA ACROSS
WEST CENTRAL MINNESOTA...WITH LOW CLOUDS TO THE WEST AND
NORTH...AND HIGH CLOUDS ACROSS THE FAR WESTERN FA. THE FAR WESTERN
FA DOES HAVE SOME FOG ISSUES AS WELL. TEMPERATURES ARE IN THE
5F TO 10F RANGE UNDER THE LOW CLOUDS...-5F TO 0F RANGE UNDER CLEAR
SKY...AND AROUND 0F WHERE THERE IS FOG. THE LOW CLOUDS APPEAR TO
BE SLOWLY MOVING EAST AND ERODING ALONG THE EDGES. 925MB WINDS
BECOME SOUTH AND INCREASE TODAY...SO EXPECT THIS TREND TO
CONTINUE. NOT MUCH CHANGE NEEDED TO THE FORECAST FOR TODAY...WITH
ONLY MINOR TWEAKS TO SKY AND TEMPERATURE BASED ON LATEST
OBSERVATIONS.
&&
.AVIATION...MVFR/IFR STRATUS DECK WILL MOVE VERY SLOWLY TO THE
EAST THROUGH THE DAY. IMPROVING CEILINGS NOT EXPECTED AT KFAR/KGFK
UNTIL 18 UTC OR LATER AND 21 UTC OR LATER AT KTVF/KBJI. SCATTERED
FLURRIES ARE POSSIBLE WITH CLOUD COVER WITH AN INFREQUENT
REDUCTION IN VISIBILITY TO 5 SM. LIGHT AND VARIABLE WIND WILL
INCREASE FROM THE SOUTH FROM WEST TO EAST AS SURFACE HIGH MOVES
INTO EASTERN MN.
&&
.PREV DISCUSSION... /ISSUED 338 AM CST FRI DEC 21 2012/
SHORT TERM...TODAY THROUGH SUNDAY NIGHT
CHALLENGE WILL BE CLOUD COVER AND TEMPERATURES TODAY AND THEN
PRECIPITATION CHANCES SUNDAY NIGHT. MODELS ARE IN GOOD AGREEMENT...
BUT WILL FOCUS ON 925 HPA RH OUTPUT FROM THE HIGH RESOLUTION RAP
FOR NEAR TERM CLOUD TRENDS.
09 UTC SATELLITE LOOP SHOWS A WEDGE OF LOW STRATUS ENCOMPASSING
ALL OF THE FORECAST AREA EXCEPT FOR EXTREME SOUTHEAST ND INTO
ADJACENT PORTIONS OF WEST CENTRAL MN. THIS AREA OF CLOUDS IS
SAGGING TO THE SOUTH AROUND 10 KTS WITH VERY LITTLE EAST-WEST
MOVEMENT. RAP SUGGESTS CLOUDS WILL MOVE VERY SLOWLY TO THE EAST
THROUGH THE DAY AS SOUTHERLY RETURN FLOW DEVELOPS ON BACKSIDE OF
DEPARTING SURFACE RIDGE. MIXING WITHIN THE RIDGE ITSELF IS ALMOST
NON-EXISTENT...SO SEE NO REASON WHY CLOUDS WOULD BREAK-UP EARLY.
FOR THIS...INCREASED SKY COVER THROUGH THE DAY ALONG AND EAST OF
THE VALLEY. THINK THERE SHOULD BE SOME CLEARING ALONG THE VALLEY
BY THIS AFTERNOON...BUT NOT UNTIL AFTER SUNSET ACROSS MUCH OF
NORTHWEST MN. DESPITE MODEST LOW-MID LEVEL WARM AIR ADVECTION...
DO NOT EXPECT MUCH TEMPERATURE RECOVERY UNDER CLOUDS..SO DECREASED
AFTERNOON HIGHS INTO THE LOW TO MID TEENS MOST LOCATIONS. SOME
SCATTERED FLURRIES ARE POSSIBLE THROUGH THE DAY...BUT NO REAL
ACCUMULATION IS EXPECTED. ALSO COULD SEE SOME PATCHY FOG EARLY
THIS MORNING ALONG THE WESTERN FLANK OF THE STRATUS DECK.
A DRY COLD FRONT WILL DROP SOUTH FROM CANADA TONIGHT AND SATURDAY.
DO NOT EXPECT ANY SNOW...BUT WINDS WILL SHIFT TO THE NORTHWEST
WITH A REINFORCING SHOT OF LOW CLOUDS. AFTERNOON HIGHS ON SATURDAY
WILL RANGE FROM 10 ABOVE ACROSS THE DEVILS LAKE BASIN TO NEAR 20
DEGREES ACROSS LAKES COUNTRY OF WEST CENTRAL MN. ANOTHER COOL...
BUT DRY DAY ON SUNDAY WITH LIGHT NORTHERLY WIND. HIGHS ACROSS
EASTERN ND INTO PORTIONS OF NORTHWEST MN NOT LIKELY TO BREAK OUT
OF THE SINGLE DIGITS.
ATTENTION TURNS TO SUNDAY NIGHT AS 700 HPA LOW MOVES INTO THE
CENTRAL VALLEY. MID-LEVEL FRONTOGENESIS AND UPPER LEVEL DYNAMIC
SUPPORT IS LACKING...BUT CONVERGENCE ALONG THE TRACK OF THE MID-
LEVEL CIRCULATION COMBINED WITH SOME WARM AIR ADVECTION INDUCED
LIFT SHOULD RESULT IN SOME LIGHT SNOW MAINLY ALONG AND NORTH OF
THE HIGHWAY TWO CORRIDOR. INCREASED POPS INTO THE 30 TO 40 PERCENT
RANGE...BUT ACCUMULATIONS SHOULD BE LIGHT...GENERALLY 1-2 INCHES
OR LESS.
LONG TERM...MONDAY THROUGH THURSDAY NIGHT
THE PATTERN WILL BEGIN WITH MAINLY ZONAL FLOW AND A CHANCE FOR
SOME LIGHT SNOW CHRISTMAS EVE WITH A SHORTWAVE. THEREAFTER...SFC
RIDGING WILL BUILD SOUTH FROM CANADA...AND RESULT IN DRY WEATHER
TUE-THU AND TEMPS BELOW NORMAL. THERE ARE SOME INDICATIONS THAT
MORE OF AN ACTIVE SW FLOW ALOFT MAY DEVELOP THU NIGHT AND FRI...
AND THE POTENTIAL FOR SOME SORT OF STORM SYSTEM...SO SOMETHING TO
MONITOR.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
401 PM EST FRI DEC 21 2012
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM OVER NEW ENGLAND WILL SLOWLY MOVE
NORTHEAST AWAY FROM THE REGION TONIGHT. A RIDGE OF HIGH PRESSURE
WILL BUILD ACROSS THE REGION ON SATURDAY AND SATURDAY NIGHT. THE
HIGH WILL THEN MOVE EAST ON SUNDAY AS A COLD FRONT APPROACHES THE
AREA FROM THE NORTHWEST.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
STRONG LOW PRESSURE NEAR NRN NEW YORK STATE THIS AFTERNOON WILL
PIVOT SLOWLY NORTHEAST AWAY FROM THE REGION OVERNIGHT.
MOSAIC RADAR CONTINUED TO SHOW CONSIDERABLE SNOW SHOWER ACTIVITY
ACROSS PARTS OF THE NRN AND ERN ZONES. MUCH OF THIS ACTIVITY
APPEARS TO BE LINKED TO A 900-850 MB FRONTOGENETIC AXIS AS
DEPICTED BY THE LATEST RAP MODEL. THE RAP MODEL GRADUALLY SHIFTS
THIS AXIS ESE AND EVENTUALLY WEAKEN IT AS IT DOES SO. THUS...WILL
FORECAST CAT POPS IN THE NRN AND EASTERN SECTIONS INTO THE EVENING
HOURS...AND THEN GRADUALLY TAPER OFF THE POPS TOWARD MIDNIGHT.
HAVE CONTINUED THE WINTER WEATHER ADVISORY UNTIL 10 PM FOR
LOCATIONS THAT WERE ALREADY IN IT AND WHERE LIKELY POPS WERE STILL
FORECAST. WILL ASSESS THE SITUATION BEFORE 6 PM TO SEE IF SOME OF
THE WESTERN COUNTIES IN THE WINTER ADVISORY ADVISORY MAY BE
DROPPED BY THEN. AS FOR THE WINDS...WE COULD SEE AN ISOLATED GUST
NEAR WIND ADVISORY CRITERIA THROUGH THE EARLY EVENING...BUT FOR
THE MOST PART...WIND GUSTS SHOULD STAY BELOW THE CRITERIA
THRESHOLD...SO HAVE ALLOWED THIS TO EXPIRE. WINDS WILL SLOWLY
DIMINISH FROM SW TO NE THROUGH THE OVERNIGHT HOURS AS LOW PRESSURE
CONTINUES TO PULL SLOWLY AWAY.
OTHERWISE...SKIES WILL BE MOSTLY CLOUDY TO CLOUDY THIS EVENING.
CLOUD COVER IS A BIT TRICKY OVERNIGHT. NAM AND GFS CONTINUE TO
DEPICTED MOISTURE AROUND 925 MB PUSHING SE AGAIN INTO THE REGION
OVERNIGHT. AS SUCH HAVE KEPT MOST LOCATIONS MOSTLY CLOUDY EXCEPT
FOR THE SW WHERE IT MAY GO MOSTLY CLEAR. OVERNIGHT LOWS WILL BE
CLOUD DEPENDENT AND WIND DEPENDENT BUT SHOULD RANGE FROM THE UPPER
TEENS SW TO THE MID 20S NORTHEAST.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
LOW PRESSURE WILL CONTINUE TO MOVE ENE ON SATURDAY AS A SFC RIDGE
OF HIGH PRESSURE BUILDS INTO THE OHIO VALLEY FROM THE WEST.
AGAIN...MODELS ARE HOLDING ON TO LOW LEVEL MOISTURE ACRS THE NRN
AND ERN SECTIONS THROUGH A GOOD PART OF THE DAY...SO HAVE GONE
PARTLY TO MOSTLY CLOUDY HERE. WE SHOULD GRADUALLY SEE IMPROVEMENT
THROUGH THE DAY SO THAT ALL LOCATIONS SHOULD BE MOSTLY CLEAR BY
SATURDAY EVENING. SKIES SHOULD REMAIN MOSTLY CLEAR SATURDAY NIGHT.
FOR SUNDAY INTO SUNDAY NIGHT...SURFACE HIGH PRESSURE RIDGE WILL
SLIP TO THE EAST. MEANWHILE...A COLD FRONT WILL DROP INTO THE
REGION SUNDAY NIGHT. MOISTURE AND LIFT ARE MEAGER TO START
WITH...SO HAVE ALLOWED FOR CLOUDS TO INCREASE OVERNIGHT...BUT LEFT
CHANCES OF PCPN UNTIL MONDAY MORNING.
AS FOR TEMPS...THEY SHOULD RANGE FROM THE LOWER TO UPPER 30S ON
SATURDAY. A MODIFYING AIRMASS AND RETURN FLOW WILL BRING
TEMPERATURES FROM THE UPPER 30S NORTH TO THE UPPER 40S SOUTH ON
SUNDAY. OVERNIGHT LOWS SATURDAY NIGHT SHOULD BE SOMEWHAT SUBDUED
WITH AN INCREASING SOUTHERLY FLOW. LOWS SUNDAY NIGHT WILL BE CLOUD
DEPENDENT BUT HAVE THEM RANGING FROM THE MID 20S NORTH TO THE
LOWER 30S SOUTH.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AN ACTIVE WEATHER PATTERN WILL EVOLVE DURING THE LONG TERM FORECAST.
WEAK LOW PRESSURE WILL BRING SPREAD PRECIPITATION ACROSS THE OHIO
VALLEY ON MONDAY. THE ONSET TIMING OF SHOWER ACTIVITY IS STILL IN
QUESTION AND WILL HELP TO DETERMINE IF WE SEE A WINTRY MIX MONDAY
MORNING...OR AN ALL RAIN EVENT DURING THE DAY MONDAY. COLDER AIR ON
THE NORTH AND EASTERN SIDE OF THE LOW WILL BRING ABOUT A CHANGEOVER
TO A RAIN/SNOW MIX AND PERHAPS A BRIEF TIME OF LIGHT SNOW MONDAY
EVENING BEFORE PRECIPITATION EXITS THE AREA. BASED ON CURRENT TIMING
OF CHANGEOVER IN THE EVENING AND LIGHT QPF AMOUNTS...DO NOT EXPECT
MUCH IN THE WAY OF ANY SNOW ACCUMULATION FROM THIS SYSTEM.
CHRISTMAS DAY LOOKS TO HAVE FAIR WEATHER WITH SEASONABLE
TEMPERATURES. THE ATTENTION THEN TURNS TO A STORM SYSTEM THAT MAY
AFFECT THE AREA CHRISTMAS NIGHT THROUGH THURSDAY MORNING. FOR THE
PAST FEW DAYS MODELS HAVE BEEN ADJUSTING THEIR FORECAST POSITIONS ON
A DEVELOPING SURFACE LOW IN THE SOUTH CENTRAL PORTIONS OF THE CONUS
AHEAD OF A DEEP TROUGH EXITING THE SOUTHERN ROCKIES ON CHRISTMAS
DAY. THE 12Z ECMWF AND GFS ARE SUGGESTING THAT THIS STORM WILL TRACK
ACROSS THE OHIO VALLEY ON WEDNESDAY. THERE ARE STILL LARGE
DIFFERENCES AMONGST THE FORECAST MODELS FOR THE EXACT LOW TRACK AND
HOW COLD TEMPERATURES WILL BE ALOFT WITH THIS LOW. WENT WITH A ECMWF
WEIGHTED CONSENSUS BLEND FOR POPS AND TEMPERATURES DURING THIS TIME
PERIOD. THE TRACK FORECAST WILL LIKELY CONTINUE TO SHIFT FROM RUN TO
RUN AS WE ARE STILL 5 DAYS OUT. WENT LIKELY FOR POPS DURING THE MOST
CONFIDENT TIME PERIOD THAT THE SYSTEM WOULD AFFECT OUR AREA.
THIS SYSTEM SHOULD EXIT THE REGION THURSDAY WITH HIGH PRESSURE
BUILDING IN FOR FRIDAY.
&&
.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
MVFR CIGS TO CONTINUE WITH CIGS IN THE 1.5-2.5 KFT RANGE THRU THE
AFTERNOON. IN CYCLONIC FLOW AROUND SFC LOW MOVG THRU THE EASTERN
GREAT LAKES...SNOW SHOWERS WILL CONTINUE TO REDUCE VSBYS TO 2-5
MILES. A FEW IFR CIGS WILL BE PSBL IN HEAVIER SNOW SHOWERS
EXPECTED ACRS KDAY AND KCMH/KLCK. PRECIP WILL END FROM SW TO NE AND
CIGS TO IMPROVE THIS EVENING. NUMERICAL MODELS SHOWING LOW LEVEL
MSTR REDEVELOPING LATE TNGT AND HAVE RE-INTRODUCED MVFR CIGS AT
KDAY/KILN. KEPT MVFR CIGS GOING AT KCMH THRU THE NIGHT ALTHOUGH
THERE MAY BE A BREAK LATE THIS EVENING PRIOR TO THE REDEVELOPMENT.
HAVE JUST BROUGHT SCTD CLOUDS BACK TO KCVG/KLUK AS THIS MOISTURE
LOOKS TO STAY TO THE NE OF THE SRN TAF SITES.
IN VERY TIGHT PRESSURE GRADIENT AROUND DEEP SFC LOW...WEST WINDS
WILL BE 25-30 KT SUSTAINED WITH GUSTS UP TO 40 KTS THIS AFTN. HIGH
PRESSURE WILL BUILD OVER THE MIDWEST TONIGHT AND WINDS WILL
GRADUALLY DIE DOWN FROM THEIR DAYTIME MAXIMA BUT STILL BE 10-15KT
GUSTING TO 25KT.
OUTLOOK...MVFR CEILINGS AND VSBYS ARE POSSIBLE MONDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR
OHZ026-035-043>046-051>056-061>065-072-074.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HICKMAN
NEAR TERM...HICKMAN
SHORT TERM...HICKMAN
LONG TERM...LATTO
AVIATION...AR
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1130 AM CST FRI DEC 21 2012
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
240 AM CST FRI DEC 21 2012
MAIN FORECAST CONCERNS TO BEGIN THE FIRST DAY OF WINTER ARE ON
TEMPERATURES TONIGHT...ANY LOW CLOUD POTENTIAL SATURDAY NIGHT INTO
SUNDAY...AND ANY PRECIPITATION POTENTIAL SUNDAY NIGHT.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED DEEP TROUGHING OFF THE WEST COAST OF THE U.S....RIDGING
BUILDING ALONG THE LEE OF THE ROCKIES INTO SOUTH CENTRAL CANADA...
AND DEEP TROUGHING FROM THE GREAT LAKES INTO THE SOUTHEASTERN U.S..
THE LATTER DEEP TROUGHING CONTAINS THE STRONG STORM SYSTEM THAT
BROUGHT THE SNOW AND STRONG WINDS TO THE FORECAST AREA YESTERDAY.
ROADS STILL REMAIN HAZARDOUS TOO...ESPECIALLY OVER THE SOUTHEASTERN
PORTION OF THE FORECAST AREA. WINDS REMAIN BRISK...DUE TO A TIGHT
PRESSURE GRADIENT BETWEEN 987MB LOW PRESSURE NEAR DETROIT AND A
1025MB HIGH PRESSURE RIDGE OVER THE EASTERN DAKOTAS. WITH THE
FORECAST AREA EXPERIENCING RISING HEIGHTS AT 500MB...ABOUT 40 METERS
SINCE 00Z ACCORDING TO THE RAP...SUBSIDENCE HAS BEEN ON THE
INCREASE. DRY ADVECTION WAS ALSO OCCURRING...NOTED BY THE
PRECIPITABLE WATER DROPPING AT MPX FROM 0.33 INCHES AT 12Z ON THE
20TH TO 0.16 INCHES AT 00Z. THE COMBINATION OF SUBSIDENCE AND DRYING
HAS LED TO CLEARING SKIES IN THE WAKE OF THE STORM SYSTEM. CLEARING
LINE STRETCHED FROM EAU CLAIRE TO LA CROSSE AND DUBUQUE. COLDER AIR
ALSO ACCOMPANYING THE SUBSIDENCE AND DRYING...REFLECTED BY SURFACE
TEMPERATURES IN THE SINGLE DIGITS ACROSS WESTERN PORTIONS OF
MINNESOTA AND IOWA...AND IN THE SINGLE DIGITS BELOW ZERO OVER THE
EASTERN DAKOTAS UNDER THE SURFACE RIDGE. 925MB TEMPS AT MPX AT 00Z
WERE -10C...ABOUT 3 COLDER THAN 12 HOURS EARLIER.
TODAY AND TONIGHT...THE UPPER RIDGING ALONG THE LEE OF THE ROCKIES
WILL SHIFT EASTWARD INTO THE PLAINS BY TONIGHT IN RESPONSE TO THE
DEEP EAST PACIFIC TROUGH APPROACHING THE WESTERN U.S. COAST. WITH
THE UPPER RIDGING TRYING TO PUSH INTO THE FORECAST AREA...MID LEVEL
HEIGHTS WILL CONTINUE TO CLIMB...MAINTAINING THE SUBSIDENCE. IN
ADDITION...THE SHIFT EAST IN THE UPPER PATTERN OCCURS AT THE SURFACE
AS WELL...WITH THE HIGH PRESSURE RIDGE SHIFTING EAST OVER THE
FORECAST AREA AROUND MIDNIGHT. WITH THE SUBSIDENCE AND DRYING
PATTERN IN PLACE...EXPECT A DRY PERIOD. IN FACT...OTHER THAN A FEW
HIGH CLOUDS AFTER MIDNIGHT TONIGHT CROSSING THE UPPER RIDGE...SKIES
SHOULD BE MAINLY CLEAR. DESPITE THE PLENTIFUL SUNSHINE TODAY...
BREEZY NORTHWEST WINDS COMBINED WITH 925MB TEMPS IN THE -6 TO -10C
RANGE AND FRESH SNOW COVER WILL LIMIT HEATING. HIGHS SHOULD TOP OUT
FROM THE MID TEENS TO MID 20S...COLDEST OVER THE HIGHER ALBEDO
PRESENT WEST OF THE MISSISSIPPI RIVER. CONCERN FOR TEMPERATURES
PLUMMETING TONIGHT GIVEN THE COOLER DAY TODAY...DECOUPLING WINDS AND
MOSTLY CLEAR SKIES. HAVE LEANED TOWARDS THE COLD SIDE OF GUIDANCE AS
A RESULT.
SATURDAY AND SATURDAY NIGHT...MODELS ARE POINTING TO A SHORTWAVE
CURRENTLY IN SOUTHEAST BRITISH COLUMBIA TOPPING THE RIDGE AND MOVING
THROUGH EASTERN LAKE SUPERIOR SATURDAY NIGHT. ALTHOUGH THIS
SHORTWAVE IS FAR FROM US...A COLD FRONT ACCOMPANIES THE SHORTWAVE
WHICH SLIDES THROUGH THE FORECAST AREA SATURDAY NIGHT. AHEAD OF THE
FRONT...WE SEE SOME 925MB WARMING...PROGGED TO CLIMB TO -2C OR SO
BY 18Z SATURDAY. 850MB TEMPS ARE EVEN WARMER...0-3C OR SO...BUT
THERE IS NO WAY OF MIXING UP TO THIS DUE TO BEING NOW AT THE
SHORTEST DAY LENGTH AND HAVING THE FRESH SNOW. NEVERTHELESS...
COMBINATION OF SUN THROUGH SOME HIGH CLOUDS AND SOUTHWEST WINDS
PICKING UP A BIT SHOULD ALLOW TEMPERATURES TO CLIMB INTO THE 20S
EVERYWHERE. SOME VALLEY LOCATIONS COULD PUSH 30. NOT ANTICIPATING
ANY PRECIPITATION TO ACCOMPANY THE FRONTAL PASSAGE...DUE TO
PLENTIFUL DRY AIR AND ALL FORCING WELL NORTHEAST OF THE AREA.
HOWEVER...AFTER THE FRONTAL PASSAGE...CONCERNED THERE MAY BE AN
INCREASE OF LOW CLOUDS AS SUGGESTED BY 21.00Z GFS 925MB RH FIELDS.
THE 21.00Z NAM AND ECMWF 925MB RH FIELD ARE NOT NEARLY AS
PESSIMISTIC AND THUS WILL CONTINUE WITH THE PREVIOUS MOSTLY CLEAR
FORECAST. COMBINATION OF COLD ADVECTION IN THE WAKE OF THE FRONT AND
RADIATIONAL COOLING ARE EXPECTED TO SEND TEMPERATURES BACK DOWN INTO
THE SINGLE DIGITS AND TEENS.
SUNDAY AND SUNDAY NIGHT...SOME OF THE CURRENT EASTERN PACIFIC TROUGH
IS PROGGED BY ALL MODELS TO HEAD EAST INTO THE PLAINS SUNDAY NIGHT.
ASSOCIATED WITH THIS UPPER TROUGHING IS A NORTHWEST TO SOUTHEAST
ORIENTED INVERTED TROUGH AT THE SURFACE...WHICH BY 12Z MONDAY SHOULD
HAVE REACHED AT LEAST SIOUX FALLS PER MODEL CONSENSUS. GIVEN THE
APPROACH OF THE UPPER AND INVERTED SURFACE TROUGH...ONE WOULD EXPECT
AN ISENTROPIC LIFT PATTERN...WHICH INDEED EXISTS. HOWEVER...ANY
ISENTROPIC LIFT IS ROOTED ON THE 290-300K SURFACES WHICH PUTS IT AT
A PRESSURE LEVEL OF 700MB OR HIGHER...AND MORE TOWARDS 12Z.
THEREFORE...NOT SURE IF ANY PRECIPITATION CAN MAKE IT TO THE
SURFACE. THE 21.00Z NAM/GFS ARE BOTH DRY FOR SUNDAY NIGHT. AS
SUCH...HAVE KEPT A DRY FORECAST GOING. LOW CLOUD COVER CONCERN STILL
EXISTS HERE FOR SUNDAY AND SUNDAY NIGHT...ESPECIALLY IF SOME MOVE IN
BEHIND THE SATURDAY NIGHT COLD FRONT. SHOULD LOW CLOUDS MOVE
IN...LIKELY SUNDAY AND SUNDAY NIGHT WILL END UP CLOUDY. CLOUDS ARE
GOING TO INCREASE ANYWAY...ESPECIALLY SUNDAY NIGHT ASSOCIATED WITH
THE ISENTROPIC LIFT REGIME AHEAD OF THE UPPER TROUGH. GIVEN THE
UNCERTAINTY SURROUNDING CLOUD COVER ON SUNDAY...WENT WITH A BLEND OF
GUIDANCE FOR HIGHS. THE BLEND OF GUIDANCE LOOKS GOOD TOO FOR LOWS
SUNDAY NIGHT AS IT HANDLES THE CLOUD COVER INCREASE FINE.
.LONG TERM...MONDAY THROUGH THURSDAY
240 AM CST FRI DEC 21 2012
21.00Z ECMWF/GFS/CANADIAN/UKMET ARE IN FAIRLY GOOD AGREEMENT BOTH
WITH THE UPPER AND SURFACE PATTERNS THROUGHOUT THE LONG TERM PERIOD.
MAIN STORM TRACK THROUGHOUT THE LONG TERM IS SOUTH OF THE FORECAST
AREA...WHERE THERE APPEARS TO BE A STORM SYSTEM THAT CROSSES THE
SOUTHERN PLAINS INTO THE MID-ATLANTIC REGION INTO NEW ENGLAND
BETWEEN TUESDAY THROUGH THURSDAY. TRENDS CONTINUE SOUTH WITH THIS
SYSTEM...THUS ALL PRECIPITATION STAYS AWAY FROM THE FORECAST AREA.
THE ONLY SYSTEM REALLY TO DEAL WITH IS THAT UPPER TROUGH AND
INVERTED TROUGH APPROACHING THE FORECAST AREA SUNDAY NIGHT. MODELS
SUGGEST THE UPPER TROUGH IS ACTUALLY SPLIT INTO TWO PARTS...WITH THE
MAIN FEATURE/SHORTWAVE IN IT TRACKING ACROSS THE OHIO RIVER VALLEY.
WE HAVE THE NORTHERN PART OF THE TROUGH CROSSING THE FORECAST
AREA MONDAY INTO MONDAY NIGHT...BUT ALL THE BETTER MOISTURE IS WITH
THE SOUTHERN SHORTWAVE. THE 21.00Z ECMWF BASICALLY CAME IN DRY WITH
THE NORTHERN PART OF THE TROUGH AND THE 21.00Z GFS ONLY HAS SOME
VERY LIGHT QPF. GIVEN THE LACK OF MOISTURE...ESPECIALLY BELOW
700MB...ONLY HAVE 20 PERCENT CHANCES OF PRECIPITATION IN THE
FORECAST FOR MONDAY AND MONDAY NIGHT. IF TRENDS CONTINUE...THESE
COULD BE PULLED IN LATER FORECASTS.
WITH A STORM TRACK MORE TO THE SOUTH OF THE FORECAST AREA...THIS
MEANS NO WARM UPS ARE IN STORE. IN FACT...THE BULK OF THE PERIOD
SHOULD AVERAGE BELOW NORMAL AS 925MB TEMPS COOL TO -10 TO -12C FOR
TUESDAY AND WEDNESDAY BEHIND THE INVERTED TROUGH. SOME SLIGHT
WARMING SHOULD OCCUR FOR THURSDAY. SOMETHING TO WATCH IS IF WE END
UP WITH CLEAR SKIES AND LIGHT WINDS AT NIGHT...SINCE SNOW COVER IS
VERY FAVORABLE FOR HAVING TEMPERATURES PLUMMET.
&&
.AVIATION...THROUGH 18Z SATURDAY
1130 AM CST FRI DEC 21 2012
A SURFACE RIDGE OF HIGH PRESSURE OVER THE CENTRAL AND NORTHERN
PLAINS WILL SLIDE EASTWARD ACROSS THE AREA TONIGHT. EXCEPT FOR A
FEW HIGH CLOUDS ON ITS BACKSIDE LATER THIS EVENING...SKIES WILL BE
CLEAR. A FEW GUSTS TO NEAR 20 KNOTS ARE POSSIBLE THROUGH 21Z TODAY
BEFORE WINDS DIMINISH TO LESS THAN 10 KNOTS AFTER 21-22Z THIS AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
240 AM CST FRI DEC 21 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RABERDING