Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 12/22/11
AREA FORECAST DISCUSSION
NWS NEW YORK NY
737 PM EST WED DEC 21 2011
.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE REGION LATER TONIGHT...FOLLOWED
BY HIGH PRESSURE FOR THURSDAY. A STORM SYSTEM TRACKS SOUTH OF LONG
ISLAND THURSDAY NIGHT AND FRIDAY MORNING...FOLLOWED BY HIGH
PRESSURE BUILDING IN TO THE NORTH THROUGH SATURDAY NIGHT...THEN
SLOWLY RETREATING TO THE NORTHEAST SUNDAY. A COLD FRONT CROSSES
THE AREA SUNDAY NIGHT...FOLLOWED BY HIGH PRESSURE BUILDING INTO
THE REGION INTO EARLY NEXT WEEK. A SERIES OF LOWS WILL ALSO PASS
TO OUR SOUTH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
ADDED PATCHY FOG EVERYWHERE THROUGH EARLY EVENING. FOG SHOULD
DISSIPATE LATER THIS EVENING AS WINDS PICK UP AHEAD OF AN
ADVANCING COLD FRONT. RAIN HAS DIMINISHED TO SPOTTY AND LIGHT OVER
THE AREA ATTM. NEXT CHANCE FOR HEAVIER PRECIP WILL ARRIVE WITH
THE COLD FRONT LATER TONIGHT. QUESTION IS HOW WELL THE CONVECTION
WITH EMBEDDED THUNDER CURRENTLY OVER WESTERN AND CENTRAL PA WILL
HOLD TOGETHER AS IT APPROACHES THE REGION. THE HRRR MODEL WEAKENS
AND SCATTERS THIS ACTIVITY BY THE TIME IT REACHES THE AREA LATER
TONIGHT. WILL RETAIN AT LEAST CHANCE POPS THROUGH 06Z FOR NOW.
GUSTY WINDS EXPECTED DUE TO A SHARP PRESSURE GRADIENT AHEAD OF
THE SURFACE LOW/COLD FRONT AND A STRONG 50-60KT LOW LEVEL JET
STREAM AT 925MB THAT WILL PASS OFFSHORE SOUTH OF LONG ISLAND.
TEMPERATURES GENERALLY HOLD STEADY UNTIL THE FROPA...THEN DROP
TONIGHT WITH COLD AIR ADVECTION DEVELOPING. LOWS WILL RANGE FROM
THE LOWER TO UPPER 40S. MAV/MET GUIDANCE BLENDED FOR TEMPS TONIGHT.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
DRY WEATHER EXPECTED THURSDAY AS THE COLD FRONT MOVES AWAY AND
WEAK HIGH PRESSURE BUILDS IN OVER THE AREA. WINDS WILL DIMINISH
BEHIND THE FRONT. PARTLY CLOUDY SKIES LIKELY IN THE MORNING...BUT
CLOUDS DEVELOP IN THE AFTERNOON AS THE NEXT SYSTEM APPROACHES.
HIGHS GENERALLY IN THE LOW 50S. MAV/MET GUIDANCE IN GOOD AGREEMENT
AND BLENDED AGAIN FOR TEMPS THURSDAY.
SURFACE LOW OVER THE SOUTHERN STATES HEADS NORTHEAST THROUGH THE
APPALACHIANS THURSDAY AND THEN APPROACHES THURSDAY NIGHT INTO
FRIDAY MORNING. FORECAST WEIGHS MORE HEAVILY ON THE 12Z
GFS/ECMWF...WHICH SHOW A 1008/1009 MB LOW EMERGING ON THE OCEAN
JUST EAST OF THE NJ COAST BY EARLY FRIDAY MORNING. NAM AN OUTLIER
AS IT TRACKS MORE FURTHER SE AND IS NOT QUITE AS STRONG. AFTER A
DRY THURSDAY...POPS INCREASE FROM WEST TO EAST THURSDAY NIGHT.
BL EXPECTED TO BE WARM ENOUGH FOR RAIN OVER MOST OF THE
REGION...BUT A WINTRY MIX CONTINUES TO BE A STRONG POSSIBILITY FOR
PORTIONS OF NE NJ...THE LOWER HUDSON VALLEY AND INTERIOR
CONNECTICUT. AT THIS POINT...EXPECTING ENOUGH RAIN TO MIX IN THAT
ANY ACCUMULATING SNOW WOULD BE LESS THAN AN INCH...BUT WILL
CONTINUE TO HAVE TO WATCH ADDITIONAL MODEL RUNS.
THURSDAY TEMPS GENERALLY IN THE LOW 50S. LOWS THURSDAY NIGHT IN
THE UPPER 30S TO LOW 40S OVER MOST OF THE REGION...EXCEPT OVER THE
LOWER HUDSON VALLEY AND INTERIOR CT WHERE LOW 30S ARE EXPECTED.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
LOW PRES SOUTH OF LONG ISLAND FRIDAY MORNING WILL CONTINUE TO TRACK
NORTHEAST AND DEPART THROUGHOUT THE DAY FRIDAY. PTYPE SHOULD
GENERALLY BE RAIN...BUT THERE MAY BE A RAIN/SNOW MIX ACROSS NORTHERN
PORTIONS OF THE INTERIOR FRIDAY MORNING WITH NO SIGNIFICANT
ACCUMULATING SNOW. RAIN TAPERS TO SHOWERS LATE FRIDAY MORNING BEFORE
ENDING BY EVENING. WEAK HIGH PRES THEN BUILDS THROUGH THE REGION
WITH DRY CONDITIONS FRIDAY NIGHT THROUGH SATURDAY NIGHT. HIGHS ON
FRIDAY WILL TOP OFF IN THE MID TO UPPER 40S...THEN LOWS FRIDAY NIGHT
AND SATURDAY NIGHT WILL DROP INTO THE LOWER 30S IN/AROUND NYC AND
COASTAL AREAS...AND INTO THE 20S IN OUTLYING AREAS. A NORTH TO
NORTHWEST FLOW ON SATURDAY WILL RESULT IN HIGHS IN THE LOW TO MID
40S.
LOW CONFIDENCE IN THE FORECAST FROM CHRISTMAS DAY SUNDAY THROUGH THE
END OF THE PERIOD.
HIGH PRES OVER EASTERN CANADA ON SATURDAY NIGHT WILL MOVE OFFSHORE
ON SUNDAY AS A TROUGH OF LOW PRES MOVES ACROSS THE GREAT LAKES AND
TOWARDS NORTHERN NY/NORTHERN NEW ENGLAND ON SUNDAY. MEANWHILE...LOW
PRES OVER THE GULF COAST WILL MOVE INTO THE SOUTHEAST U.S. AND THEN
TOWARDS THE MID-ATLANTIC STATES BEFORE MOVING OFFSHORE...POSSIBLY
MERGING WITH THE AFOREMENTIONED TROUGH OVER THE GULF OF MAINE ON
MONDAY. MODELS IN FAIR AGREEMENT...ALTHOUGH THE GFS KEEPS THE
SOUTHEAST U.S LOW TOO FAR SOUTH TO MERGE WITH THE TROUGH...UNLIKE
THE ECMWF. EITHER WAY...IN TERMS OF SENSIBLE WEATHER FOR THE LOCAL
AREA...SUNDAY GENERALLY LOOKS DRY. HOWEVER...THINK THE SOUTHERN
STREAM LOW IS TOO CLOSE TO THE LOCAL AREA TO GO COMPLETELY DRY. IN
ADDITION...THERE WILL BE SEVERAL H5 SHORTWAVES ASSOCIATED WITH AN
UPPER TROUGH APPROACHING THE REGION. WILL CARRY SLIGHT CHANCE POPS
FOR SUNDAY...AND IF ANYTHING DEVELOPS...IT SHOULD GENERALLY BE LIGHT
RAIN...POSSIBLY MIXED WITH SOME WET SNOW FLAKES. THIS COULD CHANGE
IF THE SOUTHERN STREAM LOW TAKES A MORE NORTHERLY TRACK...BUT WITH
THE TROUGH DIGGING INTO THE REGION...DO NOT THINK THIS WILL HAPPEN.
HIGH PRES BUILDS INTO THE REGION MONDAY...RESULTING IN DRY
CONDITIONS THROUGH TUESDAY MORNING BEFORE MOVING OFFSHORE ON
TUESDAY. LOW PRES THEN DEVELOPS OVER THE SOUTHEAST...AND MAY TRACK
ALONG THE COAST AND INTO THE LOCAL AREA FOR TUESDAY NIGHT AND
WEDNESDAY...BUT THE GFS AND ECMWF DIVERGE IN TIMING AND PLACEMENT OF
THE LOW. WILL CARRY SLIGHT CHANCE TO CHANCE POPS FOR NOW AND WILL
KEEP AN EYE ON ITS DEVELOPMENT.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
WARM FRONT JUST NORTH OF NY METROS WITH SUB-VFR CONDITIONS. COLD
FRONT EXPECTED TO IMPROVE CONDITIONS TONIGHT AFTER A PERIOD OF
GUSTY WINDS.
CIGS/VIS CONTINUE TO VARY BETWEEN MVFR AND IFR...BUT HAVE BEEN A
BIT MORE STABLE FOR THE PAST 2 HOURS. THERE WILL STILL BE PERIODS
OF LIFR FOR THE NEXT FEW HOURS AS MORE STEADY RAIN MOVES IN.
EXPECT LARGE DIFFERENCES AT TIMES BETWEEN TOWER VIS AND SFC VIS AS
REPORTED BY ASOS.
WINDS GENERALLY S-SE AT 10 KTS OR LESS. A FEW GUSTS POSSIBLE...BUT
WILL BE SPORADIC. WINDS TREND TO S-SW THROUGH THE AFTERNOON...BUT
DIRECTIONS WILL VARY. GUSTS REMAIN BELOW 20KTS THROUGH THE AFTERNOON.
LLWS THRESHOLDS PROBABLY NOT MET, BUT WINDS OF 40-50KT AT ABOUT
2KFT WILL RESULT IN ROUGH ASCENTS/DESCENTS.
CIGS IMPROVE TO VFR BEHIND THE COLD FRONT TNGT. WIND GUSTS TO 25
KTS POSSIBLE. A FEW WET SNOWFLAKES OR PELLETS POSSIBLE WITH ANY
SHOWERS...MAINLY SWF/BDR. NO ACCUMULATION EXPECTED.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: PDS OF LIFR POSSIBLE THROUGH LATE AFTERNOON.
AMENDMENTS POSSIBLE TO ADJUST TIMING.
KJFK FCSTER COMMENTS: PDS OF LIFR POSSIBLE THROUGH LATE AFTERNOON.
AMENDMENTS POSSIBLE TO ADJUST TIMING. WINDS COULD BE LIGHT AND
VARIABLE AT TIMES.
KLGA FCSTER COMMENTS: PDS OF LIFR POSSIBLE THROUGH LATE AFTERNOON.
AMENDMENTS POSSIBLE TO ADJUST TIMING. WINDS COULD BE LIGHT AND
VARIABLE AT TIMES.
KTEB FCSTER COMMENTS: PDS OF LIFR POSSIBLE THROUGH LATE AFTERNOON.
AMENDMENTS POSSIBLE TO ADJUST TIMING. WINDS COULD BE LIGHT AND
VARIABLE AT TIMES.
KHPN FCSTER COMMENTS: PDS OF LIFR/VLIFR POSSIBLE THROUGH LATE AFTERNOON.
AMENDMENTS POSSIBLE TO ADJUST TIMING. WINDS COULD BE LIGHT AND
VARIABLE AT TIMES.
KISP FCSTER COMMENTS: PDS OF LIFR POSSIBLE THROUGH LATE AFTERNOON.
AMENDMENTS POSSIBLE TO ADJUST TIMING. WINDS COULD BE LIGHT AND
VARIABLE AT TIMES.
OUTLOOK FOR 18Z THURSDAY THROUGH SUNDAY... THURSDAY...GENERALLY
VFR. A FEW POCKETS OF MVFR POSSIBLE...MAINLY CIGS.
THURSDAY NIGHT THROUGH EARLY FRIDAY...SUB-VFR POSSIBLE IN LOW
CIGS...RAIN...AND INLAND WINTRY MIX.
FRIDAY...VFR.
SATURDAY AND SUNDAY...VFR EARLY SATURDAY...THEN SUB
VFR IN LOW CIGS...RAIN...INLAND WINTRY MIX AT NIGHT.
MONDAY...BCGM VFR EARLY. GUSTY NW WINDS PSBL IN THE AFTERNOON.
&&
.MARINE...
A COLD FRONT APPROACHES FROM THE WEST THIS EVENING AND THEN PASSES
THROUGH THE WATERS TONIGHT. IN ADDITION TO THE SCA ON THE
OCEAN...ADDED SCA TO THE REST OF THE WATERS AS THE PRESSURE
GRADIENT TIGHTENS AND SOME MIXING MAY OCCUR FROM A STRONG 50-60 KT
LOW LEVEL JET ALOFT. COULD SEE OCCASIONAL GALE FORCE GUSTS TONIGHT
AS THE LLJ PASSES THROUGH...DEPENDING ON HOW WELL WINDS ALOFT MIX
DOWN.
WINDS AND SEAS DECREASE ON THU FALLING BELOW SCA LEVELS BY AFTN.
THERE IS THE POTENTIAL FOR SCA LEVEL SEAS WITH A COASTAL LOW PASSING
TO THE S THURSDAY NIGHT. SCA CONDITIONS...MAINLY ON THE OCEAN WATERS...ON
FRIDAY WILL GRADUALLY SUBSIDE BY FRIDAY NIGHT...THEN MAY BRIEFLY
BUILD BACK UP ON SATURDAY AFTERNOON. SUB-SCA CONDITIONS THEN
EXPECTED THROUGH SUNDAY. WITH LOW PRES PASSING SOUTH OF THE WATERS
LATE SUNDAY... WINDS AND SEAS ON THE OCEAN WILL BUILD BACK UP TO
SCA CRITERIA SUNDAY NIGHT AND MONDAY.
&&
.HYDROLOGY...
BETWEEN 1/4 AND 1/2 INCH OF RAINFALL IS EXPECTED THROUGH THIS
EVENING. ANOTHER 1/2 TO 3/4 OF LIQUID QPF IS EXPECTED THURSDAY NIGHT
INTO FRI MORNING.
NO SIGNIFICANT QPF IS EXPECTED FROM FRIDAY AFTERNOON THROUGH THE
WEEKEND.
&&
.TIDES/COASTAL FLOODING...
TIDES INCREASE ASTRONOMICALLY LATE THIS WEEK. NO COASTAL FLOODING
IS EXPECTED THURSDAY BASED ON NW FLOW. MINOR COASTAL FLOODING IS
POSSIBLE BY FRIDAY MORNING`S HIGH TIDE AS E-NE WINDS DEVELOP
ASSOCIATED WITH LOW PRESSURE PASSING SOUTH OF LONG ISLAND.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ335-338.
SMALL CRAFT ADVISORY UNTIL NOON EST THURSDAY FOR ANZ330-340-
345.
SMALL CRAFT ADVISORY UNTIL NOON EST THURSDAY FOR ANZ350-353-
355.
&&
$$
SYNOPSIS...MAS/KCS
NEAR TERM...MAS/KCS
SHORT TERM...KCS
LONG TERM...MPS
AVIATION...BS
MARINE...MPS/KCS
HYDROLOGY...MPS/KCS
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
733 PM EST WED DEC 21 2011
.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE REGION LATER TONIGHT...FOLLOWED
BY HIGH PRESSURE FOR THURSDAY. A STORM SYSTEM TRACKS SOUTH OF LONG
ISLAND THURSDAY NIGHT AND FRIDAY MORNING...FOLLOWED BY HIGH
PRESSURE BUILDING IN TO THE NORTH THROUGH SATURDAY NIGHT...THEN
SLOWLY RETREATING TO THE NORTHEAST SUNDAY. A COLD FRONT CROSSES
THE AREA SUNDAY NIGHT...FOLLOWED BY HIGH PRESSURE BUILDING INTO
THE REGION INTO EARLY NEXT WEEK. A SERIES OF LOWS WILL ALSO PASS
TO OUR SOUTH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
ADDED PATCHY FOG EVERYWHERE THROUGH EARLY EVENING. FOG SHOULD
DISSIPATE LATER THIS EVENING AS WINDS PICK UP AHEAD OF AN
ADVANCING COLD FRONT. RAIN HAS DIMINISHED TO SPOTTY AND LIGHT OVER
THE AREA ATTM. NEXT CHANCE FOR HEAVIER PRECIP WILL ARRIVE WITH
THE COLD FRONT LATER TONIGHT. QUESTION IS HOW WELL THE CONVECTION
WITH EMBEDDED THUNDER CURRENTLY OVER WESTERN AND CENTRAL PA WILL
HOLD TOGETHER AS IT APPROACHES THE REGION. THE HRRR MODEL WEAKENS
AND SCATTERS THIS ACTIVITY BY THE TIME IT REACHES THE AREA LATER
TONIGHT. WILL RETAIN AT LEAST CHANCE POPS THROUGH 06Z FOR NOW.
GUSTY WINDS EXPECTED DUE TO A SHARP PRESSURE GRADIENT AHEAD OF
THE SURFACE LOW/COLD FRONT AND A STRONG 50-60KT LOW LEVEL JET
STREAM AT 925MB THAT WILL PASS OFFSHORE SOUTH OF LONG ISLAND.
TEMPERATURES GENERALLY HOLD STEADY UNTIL THE FROPA...THEN DROP
TONIGHT WITH COLD AIR ADVECTION DEVELOPING. LOWS WILL RANGE FROM
THE LOW 30S OVER NORTHERN SECTIONS TO THE LOW 40S OVER THE NYC
METRO. MAV/MET GUIDANCE BLENDED FOR TEMPS TONIGHT.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
DRY WEATHER EXPECTED THURSDAY AS THE COLD FRONT MOVES AWAY AND
WEAK HIGH PRESSURE BUILDS IN OVER THE AREA. WINDS WILL DIMINISH
BEHIND THE FRONT. PARTLY CLOUDY SKIES LIKELY IN THE MORNING...BUT
CLOUDS DEVELOP IN THE AFTERNOON AS THE NEXT SYSTEM APPROACHES.
HIGHS GENERALLY IN THE LOW 50S. MAV/MET GUIDANCE IN GOOD AGREEMENT
AND BLENDED AGAIN FOR TEMPS THURSDAY.
SURFACE LOW OVER THE SOUTHERN STATES HEADS NORTHEAST THROUGH THE
APPALACHIANS THURSDAY AND THEN APPROACHES THURSDAY NIGHT INTO
FRIDAY MORNING. FORECAST WEIGHS MORE HEAVILY ON THE 12Z
GFS/ECMWF...WHICH SHOW A 1008/1009 MB LOW EMERGING ON THE OCEAN
JUST EAST OF THE NJ COAST BY EARLY FRIDAY MORNING. NAM AN OUTLIER
AS IT TRACKS MORE FURTHER SE AND IS NOT QUITE AS STRONG. AFTER A
DRY THURSDAY...POPS INCREASE FROM WEST TO EAST THURSDAY NIGHT.
BL EXPECTED TO BE WARM ENOUGH FOR RAIN OVER MOST OF THE
REGION...BUT A WINTRY MIX CONTINUES TO BE A STRONG POSSIBILITY FOR
PORTIONS OF NE NJ...THE LOWER HUDSON VALLEY AND INTERIOR
CONNECTICUT. AT THIS POINT...EXPECTING ENOUGH RAIN TO MIX IN THAT
ANY ACCUMULATING SNOW WOULD BE LESS THAN AN INCH...BUT WILL
CONTINUE TO HAVE TO WATCH ADDITIONAL MODEL RUNS.
THURSDAY TEMPS GENERALLY IN THE LOW 50S. LOWS THURSDAY NIGHT IN
THE UPPER 30S TO LOW 40S OVER MOST OF THE REGION...EXCEPT OVER THE
LOWER HUDSON VALLEY AND INTERIOR CT WHERE LOW 30S ARE EXPECTED.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
LOW PRES SOUTH OF LONG ISLAND FRIDAY MORNING WILL CONTINUE TO TRACK
NORTHEAST AND DEPART THROUGHOUT THE DAY FRIDAY. PTYPE SHOULD
GENERALLY BE RAIN...BUT THERE MAY BE A RAIN/SNOW MIX ACROSS NORTHERN
PORTIONS OF THE INTERIOR FRIDAY MORNING WITH NO SIGNIFICANT
ACCUMULATING SNOW. RAIN TAPERS TO SHOWERS LATE FRIDAY MORNING BEFORE
ENDING BY EVENING. WEAK HIGH PRES THEN BUILDS THROUGH THE REGION
WITH DRY CONDITIONS FRIDAY NIGHT THROUGH SATURDAY NIGHT. HIGHS ON
FRIDAY WILL TOP OFF IN THE MID TO UPPER 40S...THEN LOWS FRIDAY NIGHT
AND SATURDAY NIGHT WILL DROP INTO THE LOWER 30S IN/AROUND NYC AND
COASTAL AREAS...AND INTO THE 20S IN OUTLYING AREAS. A NORTH TO
NORTHWEST FLOW ON SATURDAY WILL RESULT IN HIGHS IN THE LOW TO MID
40S.
LOW CONFIDENCE IN THE FORECAST FROM CHRISTMAS DAY SUNDAY THROUGH THE
END OF THE PERIOD.
HIGH PRES OVER EASTERN CANADA ON SATURDAY NIGHT WILL MOVE OFFSHORE
ON SUNDAY AS A TROUGH OF LOW PRES MOVES ACROSS THE GREAT LAKES AND
TOWARDS NORTHERN NY/NORTHERN NEW ENGLAND ON SUNDAY. MEANWHILE...LOW
PRES OVER THE GULF COAST WILL MOVE INTO THE SOUTHEAST U.S. AND THEN
TOWARDS THE MID-ATLANTIC STATES BEFORE MOVING OFFSHORE...POSSIBLY
MERGING WITH THE AFOREMENTIONED TROUGH OVER THE GULF OF MAINE ON
MONDAY. MODELS IN FAIR AGREEMENT...ALTHOUGH THE GFS KEEPS THE
SOUTHEAST U.S LOW TOO FAR SOUTH TO MERGE WITH THE TROUGH...UNLIKE
THE ECMWF. EITHER WAY...IN TERMS OF SENSIBLE WEATHER FOR THE LOCAL
AREA...SUNDAY GENERALLY LOOKS DRY. HOWEVER...THINK THE SOUTHERN
STREAM LOW IS TOO CLOSE TO THE LOCAL AREA TO GO COMPLETELY DRY. IN
ADDITION...THERE WILL BE SEVERAL H5 SHORTWAVES ASSOCIATED WITH AN
UPPER TROUGH APPROACHING THE REGION. WILL CARRY SLIGHT CHANCE POPS
FOR SUNDAY...AND IF ANYTHING DEVELOPS...IT SHOULD GENERALLY BE LIGHT
RAIN...POSSIBLY MIXED WITH SOME WET SNOW FLAKES. THIS COULD CHANGE
IF THE SOUTHERN STREAM LOW TAKES A MORE NORTHERLY TRACK...BUT WITH
THE TROUGH DIGGING INTO THE REGION...DO NOT THINK THIS WILL HAPPEN.
HIGH PRES BUILDS INTO THE REGION MONDAY...RESULTING IN DRY
CONDITIONS THROUGH TUESDAY MORNING BEFORE MOVING OFFSHORE ON
TUESDAY. LOW PRES THEN DEVELOPS OVER THE SOUTHEAST...AND MAY TRACK
ALONG THE COAST AND INTO THE LOCAL AREA FOR TUESDAY NIGHT AND
WEDNESDAY...BUT THE GFS AND ECMWF DIVERGE IN TIMING AND PLACEMENT OF
THE LOW. WILL CARRY SLIGHT CHANCE TO CHANCE POPS FOR NOW AND WILL
KEEP AN EYE ON ITS DEVELOPMENT.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
A COLD FRONT WILL PUSH THROUGH LATER THIS EVENING...WITH HIGH
PRESSURE BUILDING IN THE WAKE. CONDITIONS WILL VARY BETWEEN IFR-
MVFR THROUGH 03Z...WITH THE CIGS IMPROVING AS THE PRECIP MOVES OUT
OF THE REGION. VISIBILITIES SHOULD REMAIN MVFR THROUGH THIS
TIME...AND IMPROVE TO VFR CRITERIA FOR THE REMAINDER OF THE NIGHT
INTO TOMORROW.
WINDS WILL BEGIN INCREASING RIGHT AHEAD OF THE FRONT AND CONTINUE
THROUGH 07/08Z. WINDS SHOULD GO WESTERLY AFTER THE FRONT PASSES BY
07Z. GUSTS BETWEEN 20-25 KTS EXPECTED...WITH A PERIOD OF SUSTAINED
AROUND 15 KTS IN THE EARLY MORNING. GUSTS WILL PICK UP AGAIN
TOMORROW MORNING. CONFIDENCE IS MODERATE WITH THE TIMING OF THE
GUSTS FOR TONIGHT AND TOMORROW MORNING.
THE PRECIP OVER PA IS EXPECTED TO DIMINISH GREATLY BEFORE REACHING THE
CITY TERMINALS...SO ONLY KEEPING WITH -RA THROUGH THE NEXT COUPLE
OF HOURS. ONCE THIS PRECIP MOVES TO THE EAST...NOT EXPECTING ANY
OTHER PRECIP AGAIN UNTIL TOMORROW EVENING.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: LIGHT RAIN MAY PERSIST FOR AN ADDITIONAL
HOUR OR TWO. OCCASIONAL GUSTS EXPECTED THROUGH 02Z...WITH MORE
PERSISTENT AFTER 02Z.
KJFK FCSTER COMMENTS: LIGHT RAIN MAY PERSIST FOR AN ADDITIONAL
HOUR OR TWO. IFR CONDITIONS MAY IMPROVE TO MVFR AN HOUR QUICKER
THAN IN FORECAST.
KLGA FCSTER COMMENTS: LIGHT RAIN MAY PERSIST FOR AN ADDITIONAL
HOUR OR TWO. OCCASIONAL GUSTS EXPECTED THROUGH 02Z...WITH MORE
PERSISTENT AFTER 02Z.
KTEB FCSTER COMMENTS: LIGHT RAIN MAY PERSIST FOR AN ADDITIONAL
HOUR OR TWO.
KHPN FCSTER COMMENTS: LIGHT RAIN MAY PERSIST FOR AN ADDITIONAL
HOUR OR TWO. PERIOD OF LIFR CONDITIONS MAY LINGER AN HOUR LONGER
THAN FORECASTED.
KISP FCSTER COMMENTS: LIGHT RAIN MAY PERSIST FOR AN ADDITIONAL
HOUR OR TWO.
OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
THURSDAY NIGHT THROUGH EARLY FRIDAY...SUB-VFR POSSIBLE IN LOW
CIGS...RAIN...AND INLAND WINTRY MIX.
FRIDAY-EARLY SUNDAY...VFR
SUNDAY - SUNDAY NIGHT...MAINLY VFR...WITH POSSIBLE SUB VFR WITH
ANY PRECIP.
MONDAY...BECOMING VFR EARLY. GUSTY NW WINDS POSSIBLE IN THE
AFTERNOON.
&&
.MARINE...
A COLD FRONT APPROACHES FROM THE WEST THIS EVENING AND THEN PASSES
THROUGH THE WATERS TONIGHT. IN ADDITION TO THE SCA ON THE
OCEAN...ADDED SCA TO THE REST OF THE WATERS AS THE PRESSURE
GRADIENT TIGHTENS AND SOME MIXING MAY OCCUR FROM A STRONG 50-60 KT
LOW LEVEL JET ALOFT. COULD SEE OCCASIONAL GALE FORCE GUSTS TONIGHT
AS THE LLJ PASSES THROUGH...DEPENDING ON HOW WELL WINDS ALOFT MIX
DOWN.
WINDS AND SEAS DECREASE ON THU FALLING BELOW SCA LEVELS BY AFTN.
THERE IS THE POTENTIAL FOR SCA LEVEL SEAS WITH A COASTAL LOW PASSING
TO THE S THURSDAY NIGHT. SCA CONDITIONS...MAINLY ON THE OCEAN WATERS...ON
FRIDAY WILL GRADUALLY SUBSIDE BY FRIDAY NIGHT...THEN MAY BRIEFLY
BUILD BACK UP ON SATURDAY AFTERNOON. SUB-SCA CONDITIONS THEN
EXPECTED THROUGH SUNDAY. WITH LOW PRES PASSING SOUTH OF THE WATERS
LATE SUNDAY... WINDS AND SEAS ON THE OCEAN WILL BUILD BACK UP TO
SCA CRITERIA SUNDAY NIGHT AND MONDAY.
&&
.HYDROLOGY...
BETWEEN 1/4 AND 1/2 INCH OF RAINFALL IS EXPECTED THROUGH THIS
EVENING. ANOTHER 1/2 TO 3/4 OF LIQUID QPF IS EXPECTED THURSDAY NIGHT
INTO FRI MORNING.
NO SIGNIFICANT QPF IS EXPECTED FROM FRIDAY AFTERNOON THROUGH THE
WEEKEND.
&&
.TIDES/COASTAL FLOODING...
TIDES INCREASE ASTRONOMICALLY LATE THIS WEEK. NO COASTAL FLOODING
IS EXPECTED THURSDAY BASED ON NW FLOW. MINOR COASTAL FLOODING IS
POSSIBLE BY FRIDAY MORNING`S HIGH TIDE AS E-NE WINDS DEVELOP
ASSOCIATED WITH LOW PRESSURE PASSING SOUTH OF LONG ISLAND.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ335-338.
SMALL CRAFT ADVISORY UNTIL NOON EST THURSDAY FOR ANZ330-340-
345.
SMALL CRAFT ADVISORY UNTIL NOON EST THURSDAY FOR ANZ350-353-
355.
&&
$$
SYNOPSIS...MAS/KCS
NEAR TERM...MAS/KCS
SHORT TERM...KCS
LONG TERM...MPS
AVIATION...BS
MARINE...MPS/KCS
HYDROLOGY...MPS/KCS
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
639 PM EST WED DEC 21 2011
.SYNOPSIS...
A SLOW MOVING FRONTAL SYSTEM WILL REMAIN NEAR THE FORECAST AREA
THROUGH THE CHRISTMAS WEEKEND. A SERIES OF LOW PRESSURE SYSTEMS WILL
MOVE NORTHEASTWARD ALONG THE FRONT.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
WARM ADVECTION PATTERN PERSISTS ACROSS THE FORECAST AREA WITH
ADEQUATE MOISTURE EVIDENT ON THE 21Z RUC ANALYSIS SOUNDING.
PRECIPITABLE WATER VALUES ARE MAXIMIZED ACROSS THE MIDLANDS WITH
VALUES AROUND 1.5 INCHES...HOWEVER THE BEST MOISTURE TRANSPORT IS
SHIFTING NORTHEAST OF THE FORECAST AREA. THIS CAN BE SEEN IN THE
REGIONAL RADAR MOSAIC WHERE A CLUSTER OF RAIN IS LIFTING OUT OF
THE NORTHEASTERN PART OF THE FORECAST AREA WITH MAINLY FEW TO
SCATTERED SHOWERS REMAINING ACROSS THE AREA.
HAVE UPDATED THE POP FORECAST TO MORE ACCURATELY DEPICT THE
CURRENT ACTIVITY AND EXPECT THE COVERAGE SHOULD CONTINUE TO
DIMINISH INTO THE EVENING AND OVERNIGHT HOURS AS THE 850MB JET
SHIFTS EAST AND MOISTURE TRANSPORT CONTINUES TO WANE. EXPECT
TEMPERATURES TO MOVE LITTLE OVER THE NEXT SEVERAL HOURS WITH
OVERCAST SKIES AND LOW DEWPOINT DEPRESSIONS AND A WELL MIXED
BOUNDARY LAYER. LOWS TONIGHT WILL BE QUITE MILD AND COULD POSSIBLE
SET A RECORD WARMEST LOW AT COLUMBIA.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
CONVERGENCE AND MOISTURE ASSOCIATED WITH THE SLOW MOVING FRONT WILL
SUPPORT A CONTINUED SHOWER CHANCE. THE GREATER CHANCE MAY BE
THURSDAY NIGHT ASSOCIATED WITH STRONGER CONVERGENCE AHEAD OF THE
FRONT. THE NAM AND GFS SHOW SOME DRYING DEVELOPING FRIDAY AS THE
FRONT PUSHES A LITTLE FARTHER SOUTHEASTWARD. THERE HAVE BEEN
INCONSISTENCIES WITH PREVIOUS RUNS WITH THE TIMING OF THE FRONT
AND A SERIES OF MID-LEVEL SHORTWAVE TROUGHS. USED THE GUIDANCE
CONSENSUS FOR THE POP FORECAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
THE GFS SHOWED THE FRONT LINGERING NEAR THE FORECAST AREA THROUGH
CHRISTMAS DAY WITH DRYING MONDAY. THE MODEL SHOWED ANOTHER WAVE
DEVELOPING AND PUSHING HIGHER MOISTURE BACK INTO THE FORECAST AREA
MONDAY NIGHT AND TUESDAY. RIDGING APPEARED TO BECOME DOMINATE
WEDNESDAY. THE GFS AND ECMWF HAVE TRENDED INTO BETTER AGREEMENT WITH
HIGH MOISTURE CHRISTMAS DAY. THE GFS ENSEMBLES CONTINUED TO DISPLAY
HIGH SPREAD ASSOCIATED WITH THE COMPLEX SPLIT FLOW PATTERN.
CONFIDENCE REMAINED LOW WITH THE FORECAST THROUGH THE EXTENDED
PERIOD. LEANED TOWARD THE GFS ENSEMBLE MEAN POPS.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
SCATTERED AREAS OF LIGHT RAIN HAVE DIMINISHED ACROSS THE MIDLANDS.
ADDITIONAL RAINFALL ACROSS EAST-CENTRAL GA WILL MOVE TOWARDS AND
INTO THE CSRA THROUGH 03Z. WILL INCLUDE MENTION OF VCSH IN CSRA
TAFS THROUGH 06Z...WITH OTHER SITES REMAINING DRY FOR NOW.
STILL EXPECT MVFR/IFR CONDITIONS TO DEVELOP THROUGH THE OVERNIGHT
HOURS...WITH AREAS OF FOG DEVELOPING LATE TONIGHT. BUFKIT CONTINUES
WITH HIGH LOW-LEVEL MOISTURE AND BRINGS IN SOME SLIGHTLY DRIER AIR
ALOFT BY MORNING. MODELS ALL SHOWING POSSIBLE LIFR/IFR CONDITIONS
BY MORNING...WITH VISIBILITIES LESS THAN A HALF A MILE. FOR NOW
WILL NOT GO THAT LOW...BUT WILL DROP VISIBILITIES IN THE MIDLANDS
AND CSRA DOWN TO 1SM IN BR. WILL NEED TO MONITOR OVERNIGHT THROUGH.
CONDITIONS WILL SLOWLY IMPROVE AFTER 16Z THURSDAY WITH IFR CIGS AND
MVFR VSBYS. VFR CONDITIONS POSSIBLE AFTER 22Z THURSDAY FOR A PERIOD
IN THE AFTERNOON.
EXTENDED AVIATION OUTLOOK...PERIODS OF CIG/VSBY RESTRICTIONS
EXPECTED THROUGH SATURDAY AS A SERIES OF WEATHER SYSTEMS CROSS THE
REGION.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
149 PM EST TUE DEC 20 2011
.AVIATION...
WMFNTL BNDRY ALG THE OH RVR WILL CONT TO ADVT SLOWLY NWD THIS PD.
THUS WIDESPREAD MVFR/IFR CIGS WILL CONT W/A GRADUAL DETERIORATION
XPCD OVERNIGHT AS SFC BNDRY NEARS CLOSER...LL FLW BACKS MORE SRLY
AND DRY SLOT BLDG IN OVERHEAD LEADING TO AREAS OF DZ. PRIOR FCST HAD
THIS WELL IN HAND AND CARRIED FORWARD W/JUST A FEW TWEAKS. IMPROVING
CONDS XPCD JUST AFT THE END OF THIS PD WED AFTN AS UPR TROF OPENS
AND ACCELERATES NEWD INTO THE ERN LAKES.
&&
.PREV DISCUSSION... /ISSUED 419 AM EST TUE DEC 20 2011/
SHORT TERM.../TODAY THROUGH WEDNESDAY NIGHT/
STRONG ISENTROPIC LIFT HAS ALLOWED FOR BAND OF PERSISTENT PRECIP
FROM SOUTHERN QUARTER OR SO OF THE FORECAST AREA BACK TO THE WEST
ACROSS MUCH OF CENTRAL AND SOUTHERN ILLINOIS. EARLIER TAMDAR
SOUNDINGS INDICATED THAT RISK FOR SNOW MAY BE MINIMAL INTO TUES
MORNING. HOWEVER...RECENT SFC OBS AND CALL AROUND TO CENTRAL
DISPATCHES IN SOUTHERN AREAS SHOWS RAIN HAS BEEN MIXING WITH AND
EVEN CHANGING TO SOME LIGHT SNOW. MAIN SWITCH OVER HAS BEEN
OCCURRING IN SE AREAS WHERE NE FLOW HAS ALLOWED SLIGHTLY COLDER
TEMPS TO MIX FURTHER THROUGH THE COLUMN. SFC TEMPS WERE ABOVE
FREEZING ACROSS THE AREA WITH ANY SNOW MELTING AS IT FALLS. OF
CONCERN IS NEW 6Z NAM12 WHICH SUGGEST A SWATH OF LOCALLY HEAVIER
PRECIP MAY ARRIVE TOWARDS 12Z AND FALL IN AREA WHERE COOLING MAY BE
MAXIMIZED. GRIDS HAVE HAD LIGHT ACCUMS IN FOR SEVERAL DAYS AND HAVE
KEPT THIS THINKING GENERALLY THE SAME THROUGH THIS MORNING. KFWA
OBSERVER JUST CONTACTED US WITH A FEW TENTHS OF AN INCH ON VEHICLES
BUT EVERYTHING MELTING ON THE GROUND. BLEND OF RUC AND LOCAL WRF WAS
USED TO GET POP LAYOUT TODAY WITH VERY TIGHT CUT OFF TO THE NORTH AS
LOCATIONS NORTH OF US 6 MAY SEE LITTLE OR NO PRECIPITATION. LOCAL
WRF AND HRRR WANT TO QUICKLY DRY THINGS OUT IN THE 21 TO 00Z TIME
FRAME AS BEST FORCING SHIFTS NORTH WITH THE WARM FRONT PASSING
THROUGH. THIS COULD LEAVE MUCH OF THE AREA EITHER DRY OR WITH SOME
AREAS OF DRIZZLE. HAVE MADE NO CHANGES TO THIS AFTERNOON WITH CHC
POPS REMAINING IN FAR N AND NW AREAS AND LIKELY REMAINDER OF THE
AREA. WILL LET DAY SHIFT MONITOR TRENDS.
UPPER LOW WILL TRACK TOWARDS THE REGION LATER TONIGHT INTO WEDS.
MODELS STILL VARY ON PATH OF THIS FEATURE EITHER BEING OVER THE AREA
OR JUST TO THE SE. STILL THINK MOST AREAS WILL SEE A CHANCE FOR
LIGHT RAIN FOR AT LEAST A 6 TO 12 HOUR PERIOD BEFORE ENDING BY WEDS
EVENING.
IN TERMS OF TEMPS THROUGH THE PERIOD...EXPECTING LITTLE OVERALL
CHANGE IN SFC TEMPS TODAY ACROSS THE NORTH AND A SLOW WARM UP IN
SOUTHERN AREAS ESPECIALLY AS WARM FRONT MOVES NORTH. IF ANY BREAKS
IN THE CLOUDS CAN FORM LATER THIS AFTERNOON...COULD SEE HIGHS WARMER
THAN FORECAST. HOWEVER...OBS TO THE SOUTH SHOW PRETTY EXTENSIVE
CLOUD COVER SO WILL HOLD OFF ON ANY CHANGES FOR HIGHS TODAY. HIGHS
ON WEDS COULD VARY GREATLY DEPENDING ON THE TRACK OF THE UPPER LOW
WITH WARMEST READINGS SE WHERE HIGHS COULD EASILY CLIMB INTO THE
50S. OVERNIGHT LOWS BOTH NIGHTS EXPECTED TO REMAIN ABOVE FREEZING.
LONG TERM.../THURSDAY THROUGH MONDAY/
NEXT IN SERIES OF SRN STREAMS SHRTWVS EMANATING FROM SPLIT FLOW
OVER WRN U.S. WILL LIFT RAPIDLY NE FROM THE SRN PLAINS TO THE LWR
OH VALLEY THU EVE. THIS SYSTEM SHOULD BE CONSIDERABLY WEAKER THAN
ITS PREDECESSOR DUE TO MORE SHEARING FM INTERACTION WITH NRN
STREAM SHRTWV MOVG ESE INTO THE UPR GRTLKS AT THE SAME TIME. PER
GFS SOLUTION... SFC/H85 BAROCLINIC ZONE EXPECTED TO REMAIN FAR
ENOUGH TO THE S-SE TO KEEP NWRN EDGE OF PRECIP SHIELD WITH THIS
SYSTEM JUST SE OF OUR CWA. WK WAA AHEAD OF THE NRN STREAM
SHRTWV/CDFNT SHOULD ALLOW HIGHS TO REACH THE L-M40S ACROSS THE
AREA DESPITE CONSIDERABLE CLOUDINESS.
CDFNT WILL MOVE THROUGH THE AREA BY THU EVE WITH HIGH PRESSURE OVER
THE NRN PLAINS BUILDING EAST ACROSS THE WRN GRTLKS IN ITS WAKE. WK
CONVERGENCE ALONG FRONT AS IT MERGES WITH CIRCULATION OF SURFACE LOW
TO THE SE SUGGESTS JUST SOME CLOUDINESS WILL ACCOMPANY IT... BUT
LITTLE CHC OF MEASURABLE PRECIP. FAIRLY WK CAA WITH H85 TEMPS ONLY
FALLING TO -2C/-4C ACROSS THE CWA COMBINED WITH CLOUDINESS SUGGESTS
LOWS WILL ONLY BE IN THE U20S/L30S THU NGT.
FOR THE EXTENDED DAYS 4-7...MEDIUM RANGE MODELS IN DECENT AGREEMENT
INDICATING MEAN TROF OVER WRN U.S. IN SHORT TERM WILL PROGRESS TO
NEAR THE EAST COAST BY THE END OF THE LONG TERM PERIOD. THIS SHOULD
RESULT IN A GRADUAL COOL DOWN OVER THE HOLIDAY WEEKEND WITH A WARMUP
EARLY NEXT WEEK AS RIDGING ALOFT MOVES INTO THE GRTLKS IN THE WAKE
OF THIS TROF. SPLIT FLOW WILL PERSIST AS THE MEAN TROF MOVES EAST...
AT LEAST THROUGH FRIDAY OR SAT. MODELS HAVE VERY DIFFERENT
TIMING/TRACK/INTENSITY WITH SHRTWV LIFTING OUT OF THE SRN STREAM
FLOW OVER THE WEEKEND... THUS LITTLE CONFIDENCE IN THE POPS SATURDAY
BUT MAINTAINED FCST CONTINUITY BY FOLLOWING GFS SOLUTION WHICH
INDICATES A CHC OF RAIN/SNOW IN OUR AREA AROUND THIS PERIOD. IN THE
WAKE OF THIS SYSTEM... NRN STREAM TROF PROGGED TO STRENGTHEN/DIG SE
A BIT WHICH SHOULD ALLOW AIRMASS OVER THE WRN GRTLKS TO BECOME COLD
ENOUGH FOR SOME LAKE EFFECT SNOW SHOWERS BY LATE SUNDAY... THOUGH
DOESN`T LOOK LIKE A FAVORABLE SETUP FOR SGFNT LES ATTM WITH GFS
INDICATING FAIRLY LOW INVERSION HEIGHTS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...FISHER
LONG TERM...JT
AVIATION...T
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
643 AM EST TUE DEC 20 2011
.AVIATION...
MOIST SOUTHERLY FLOW AHEAD OF STRONG SRN PLAINS LOW OVER-RUNNING
STALLED CDFNT OVER SRN INDIANA/OH RESULTING IN AN E-W BAND OF
PRECIP WITH IFR CONDITIONS ACROSS NRN INDIANA THIS MORNING. AS
LOW CONTINUES TO MOVE NE TODAY FRONT WILL LIFT SLOWLY NORTH AS A
WARM FRONT CAUSING RNSN MIX TO CHANGE OVER TO ALL RAIN BY MID-
MORNING AT FWA. MID LEVEL DRY SLOT SHOULD OVERSPREAD THE AREA THIS
AFTN ENDING OVER-RUNNING PRECIP...LIKELY BEFORE IT REACHES SBN.
IFR CONDITIONS SHOULD PERSIST AT FWA THROUGH THE DAY WITH CEILINGS
LOWERING TO MVFR AT SBN. AS WARM FRONT CONTS TO LIFT NORTH INTO
NRN INDIANA TONIGHT EXPECT FLYING CONDITIONS TO LOWER TO LIFR WITH
STRATUS/FOG AND LIGHT RAIN/DRIZZLE.
&&
.PREV DISCUSSION... /ISSUED 419 AM EST TUE DEC 20 2011/
SHORT TERM.../TODAY THROUGH WEDNESDAY NIGHT/
STRONG ISENTROPIC LIFT HAS ALLOWED FOR BAND OF PERSISTENT PRECIP
FROM SOUTHERN QUARTER OR SO OF THE FORECAST AREA BACK TO THE WEST
ACROSS MUCH OF CENTRAL AND SOUTHERN ILLINOIS. EARLIER TAMDAR
SOUNDINGS INDICATED THAT RISK FOR SNOW MAY BE MINIMAL INTO TUES
MORNING. HOWEVER...RECENT SFC OBS AND CALL AROUND TO CENTRAL
DISPATCHES IN SOUTHERN AREAS SHOWS RAIN HAS BEEN MIXING WITH AND
EVEN CHANGING TO SOME LIGHT SNOW. MAIN SWITCH OVER HAS BEEN
OCCURRING IN SE AREAS WHERE NE FLOW HAS ALLOWED SLIGHTLY COLDER
TEMPS TO MIX FURTHER THROUGH THE COLUMN. SFC TEMPS WERE ABOVE
FREEZING ACROSS THE AREA WITH ANY SNOW MELTING AS IT FALLS. OF
CONCERN IS NEW 6Z NAM12 WHICH SUGGEST A SWATH OF LOCALLY HEAVIER
PRECIP MAY ARRIVE TOWARDS 12Z AND FALL IN AREA WHERE COOLING MAY BE
MAXIMIZED. GRIDS HAVE HAD LIGHT ACCUMS IN FOR SEVERAL DAYS AND HAVE
KEPT THIS THINKING GENERALLY THE SAME THROUGH THIS MORNING. KFWA
OBSERVER JUST CONTACTED US WITH A FEW TENTHS OF AN INCH ON VEHICLES
BUT EVERYTHING MELTING ON THE GROUND. BLEND OF RUC AND LOCAL WRF WAS
USED TO GET POP LAYOUT TODAY WITH VERY TIGHT CUT OFF TO THE NORTH AS
LOCATIONS NORTH OF US 6 MAY SEE LITTLE OR NO PRECIPITATION. LOCAL
WRF AND HRRR WANT TO QUICKLY DRY THINGS OUT IN THE 21 TO 00Z TIME
FRAME AS BEST FORCING SHIFTS NORTH WITH THE WARM FRONT PASSING
THROUGH. THIS COULD LEAVE MUCH OF THE AREA EITHER DRY OR WITH SOME
AREAS OF DRIZZLE. HAVE MADE NO CHANGES TO THIS AFTERNOON WITH CHC
POPS REMAINING IN FAR N AND NW AREAS AND LIKELY REMAINDER OF THE
AREA. WILL LET DAY SHIFT MONITOR TRENDS.
UPPER LOW WILL TRACK TOWARDS THE REGION LATER TONIGHT INTO WEDS.
MODELS STILL VARY ON PATH OF THIS FEATURE EITHER BEING OVER THE AREA
OR JUST TO THE SE. STILL THINK MOST AREAS WILL SEE A CHANCE FOR
LIGHT RAIN FOR AT LEAST A 6 TO 12 HOUR PERIOD BEFORE ENDING BY WEDS
EVENING.
IN TERMS OF TEMPS THROUGH THE PERIOD...EXPECTING LITTLE OVERALL
CHANGE IN SFC TEMPS TODAY ACROSS THE NORTH AND A SLOW WARM UP IN
SOUTHERN AREAS ESPECIALLY AS WARM FRONT MOVES NORTH. IF ANY BREAKS
IN THE CLOUDS CAN FORM LATER THIS AFTERNOON...COULD SEE HIGHS WARMER
THAN FORECAST. HOWEVER...OBS TO THE SOUTH SHOW PRETTY EXTENSIVE
CLOUD COVER SO WILL HOLD OFF ON ANY CHANGES FOR HIGHS TODAY. HIGHS
ON WEDS COULD VARY GREATLY DEPENDING ON THE TRACK OF THE UPPER LOW
WITH WARMEST READINGS SE WHERE HIGHS COULD EASILY CLIMB INTO THE
50S. OVERNIGHT LOWS BOTH NIGHTS EXPECTED TO REMAIN ABOVE FREEZING.
LONG TERM.../THURSDAY THROUGH MONDAY/
NEXT IN SERIES OF SRN STREAMS SHRTWVS EMANATING FROM SPLIT FLOW
OVER WRN U.S. WILL LIFT RAPIDLY NE FROM THE SRN PLAINS TO THE LWR
OH VALLEY THU EVE. THIS SYSTEM SHOULD BE CONSIDERABLY WEAKER THAN
ITS PREDECESSOR DUE TO MORE SHEARING FM INTERACTION WITH NRN
STREAM SHRTWV MOVG ESE INTO THE UPR GRTLKS AT THE SAME TIME. PER
GFS SOLUTION... SFC/H85 BAROCLINIC ZONE EXPECTED TO REMAIN FAR
ENOUGH TO THE S-SE TO KEEP NWRN EDGE OF PRECIP SHIELD WITH THIS
SYSTEM JUST SE OF OUR CWA. WK WAA AHEAD OF THE NRN STREAM
SHRTWV/CDFNT SHOULD ALLOW HIGHS TO REACH THE L-M40S ACROSS THE
AREA DESPITE CONSIDERABLE CLOUDINESS.
CDFNT WILL MOVE THROUGH THE AREA BY THU EVE WITH HIGH PRESSURE OVER
THE NRN PLAINS BUILDING EAST ACROSS THE WRN GRTLKS IN ITS WAKE. WK
CONVERGENCE ALONG FRONT AS IT MERGES WITH CIRCULATION OF SURFACE LOW
TO THE SE SUGGESTS JUST SOME CLOUDINESS WILL ACCOMPANY IT... BUT
LITTLE CHC OF MEASURABLE PRECIP. FAIRLY WK CAA WITH H85 TEMPS ONLY
FALLING TO -2C/-4C ACROSS THE CWA COMBINED WITH CLOUDINESS SUGGESTS
LOWS WILL ONLY BE IN THE U20S/L30S THU NGT.
FOR THE EXTENDED DAYS 4-7...MEDIUM RANGE MODELS IN DECENT AGREEMENT
INDICATING MEAN TROF OVER WRN U.S. IN SHORT TERM WILL PROGRESS TO
NEAR THE EAST COAST BY THE END OF THE LONG TERM PERIOD. THIS SHOULD
RESULT IN A GRADUAL COOL DOWN OVER THE HOLIDAY WEEKEND WITH A WARMUP
EARLY NEXT WEEK AS RIDGING ALOFT MOVES INTO THE GRTLKS IN THE WAKE
OF THIS TROF. SPLIT FLOW WILL PERSIST AS THE MEAN TROF MOVES EAST...
AT LEAST THROUGH FRIDAY OR SAT. MODELS HAVE VERY DIFFERENT
TIMING/TRACK/INTENSITY WITH SHRTWV LIFTING OUT OF THE SRN STREAM
FLOW OVER THE WEEKEND... THUS LITTLE CONFIDENCE IN THE POPS SATURDAY
BUT MAINTAINED FCST CONTINUITY BY FOLLOWING GFS SOLUTION WHICH
INDICATES A CHC OF RAIN/SNOW IN OUR AREA AROUND THIS PERIOD. IN THE
WAKE OF THIS SYSTEM... NRN STREAM TROF PROGGED TO STRENGTHEN/DIG SE
A BIT WHICH SHOULD ALLOW AIRMASS OVER THE WRN GRTLKS TO BECOME COLD
ENOUGH FOR SOME LAKE EFFECT SNOW SHOWERS BY LATE SUNDAY... THOUGH
DOESN`T LOOK LIKE A FAVORABLE SETUP FOR SGFNT LES ATTM WITH GFS
INDICATING FAIRLY LOW INVERSION HEIGHTS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...FISHER
LONG TERM...JT
AVIATION...JT
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
419 AM EST TUE DEC 20 2011
.SHORT TERM.../TODAY THROUGH WEDNESDAY NIGHT/
STRONG ISENTROPIC LIFT HAS ALLOWED FOR BAND OF PERSISTENT PRECIP
FROM SOUTHERN QUARTER OR SO OF THE FORECAST AREA BACK TO THE WEST
ACROSS MUCH OF CENTRAL AND SOUTHERN ILLINOIS. EARLIER TAMDAR
SOUNDINGS INDICATED THAT RISK FOR SNOW MAY BE MINIMAL INTO TUES
MORNING. HOWEVER...RECENT SFC OBS AND CALL AROUND TO CENTRAL
DISPATCHES IN SOUTHERN AREAS SHOWS RAIN HAS BEEN MIXING WITH AND
EVEN CHANGING TO SOME LIGHT SNOW. MAIN SWITCH OVER HAS BEEN
OCCURRING IN SE AREAS WHERE NE FLOW HAS ALLOWED SLIGHTLY COLDER
TEMPS TO MIX FURTHER THROUGH THE COLUMN. SFC TEMPS WERE ABOVE
FREEZING ACROSS THE AREA WITH ANY SNOW MELTING AS IT FALLS. OF
CONCERN IS NEW 6Z NAM12 WHICH SUGGEST A SWATH OF LOCALLY HEAVIER
PRECIP MAY ARRIVE TOWARDS 12Z AND FALL IN AREA WHERE COOLING MAY BE
MAXIMIZED. GRIDS HAVE HAD LIGHT ACCUMS IN FOR SEVERAL DAYS AND HAVE
KEPT THIS THINKING GENERALLY THE SAME THROUGH THIS MORNING. KFWA
OBSERVER JUST CONTACTED US WITH A FEW TENTHS OF AN INCH ON VEHICLES
BUT EVERYTHING MELTING ON THE GROUND. BLEND OF RUC AND LOCAL WRF WAS
USED TO GET POP LAYOUT TODAY WITH VERY TIGHT CUT OFF TO THE NORTH AS
LOCATIONS NORTH OF US 6 MAY SEE LITTLE OR NO PRECIPITATION. LOCAL
WRF AND HRRR WANT TO QUICKLY DRY THINGS OUT IN THE 21 TO 00Z TIME
FRAME AS BEST FORCING SHIFTS NORTH WITH THE WARM FRONT PASSING
THROUGH. THIS COULD LEAVE MUCH OF THE AREA EITHER DRY OR WITH SOME
AREAS OF DRIZZLE. HAVE MADE NO CHANGES TO THIS AFTERNOON WITH CHC
POPS REMAINING IN FAR N AND NW AREAS AND LIKELY REMAINDER OF THE
AREA. WILL LET DAY SHIFT MONITOR TRENDS.
UPPER LOW WILL TRACK TOWARDS THE REGION LATER TONIGHT INTO WEDS.
MODELS STILL VARY ON PATH OF THIS FEATURE EITHER BEING OVER THE AREA
OR JUST TO THE SE. STILL THINK MOST AREAS WILL SEE A CHANCE FOR
LIGHT RAIN FOR AT LEAST A 6 TO 12 HOUR PERIOD BEFORE ENDING BY WEDS
EVENING.
IN TERMS OF TEMPS THROUGH THE PERIOD...EXPECTING LITTLE OVERALL
CHANGE IN SFC TEMPS TODAY ACROSS THE NORTH AND A SLOW WARM UP IN
SOUTHERN AREAS ESPECIALLY AS WARM FRONT MOVES NORTH. IF ANY BREAKS
IN THE CLOUDS CAN FORM LATER THIS AFTERNOON...COULD SEE HIGHS WARMER
THAN FORECAST. HOWEVER...OBS TO THE SOUTH SHOW PRETTY EXTENSIVE
CLOUD COVER SO WILL HOLD OFF ON ANY CHANGES FOR HIGHS TODAY. HIGHS
ON WEDS COULD VARY GREATLY DEPENDING ON THE TRACK OF THE UPPER LOW
WITH WARMEST READINGS SE WHERE HIGHS COULD EASILY CLIMB INTO THE
50S. OVERNIGHT LOWS BOTH NIGHTS EXPECTED TO REMAIN ABOVE FREEZING.
&&
.LONG TERM.../THURSDAY THROUGH MONDAY/
NEXT IN SERIES OF SRN STREAMS SHRTWVS EMANATING FROM SPLIT FLOW OVER
WRN U.S. WILL LIFT RAPIDLY NE FROM THE SRN PLAINS TO THE LWR OH
VALLEY THU EVE. THIS SYSTEM SHOULD BE CONSIDERABLY WEAKER THAN ITS
PREDECESSOR DUE TO MORE SHEARING FM INTERACTION WITH NRN STREAM
SHRTWV MOVG ESE INTO THE UPR GRTLKS AT THE SAME TIME. PER GFS
SOLUTION... SFC/H85 BAROCLINIC ZONE EXPECTED TO REMAIN FAR ENOUGH TO
THE S-SE TO KEEP NWRN EDGE OF PRECIP SHIELD WITH THIS SYSTEM JUST SE
OF OUR CWA. WK WAA AHEAD OF THE NRN STREAM SHRTWV/CDFNT SHOULD ALLOW
HIGHS TO REACH THE L-M40S ACROSS THE AREA DESPITE CONSIDERABLE
CLOUDINESS.
CDFNT WILL MOVE THROUGH THE AREA BY THU EVE WITH HIGH PRESSURE OVER
THE NRN PLAINS BUILDING EAST ACROSS THE WRN GRTLKS IN ITS WAKE. WK
CONVERGENCE ALONG FRONT AS IT MERGES WITH CIRCULATION OF SURFACE LOW
TO THE SE SUGGESTS JUST SOME CLOUDINESS WILL ACCOMPANY IT... BUT
LITTLE CHC OF MEASURABLE PRECIP. FAIRLY WK CAA WITH H85 TEMPS ONLY
FALLING TO -2C/-4C ACROSS THE CWA COMBINED WITH CLOUDINESS SUGGESTS
LOWS WILL ONLY BE IN THE U20S/L30S THU NGT.
FOR THE EXTENDED DAYS 4-7...MEDIUM RANGE MODELS IN DECENT AGREEMENT
INDICATING MEAN TROF OVER WRN U.S. IN SHORT TERM WILL PROGRESS TO
NEAR THE EAST COAST BY THE END OF THE LONG TERM PERIOD. THIS SHOULD
RESULT IN A GRADUAL COOL DOWN OVER THE HOLIDAY WEEKEND WITH A WARMUP
EARLY NEXT WEEK AS RIDGING ALOFT MOVES INTO THE GRTLKS IN THE WAKE
OF THIS TROF. SPLIT FLOW WILL PERSIST AS THE MEAN TROF MOVES EAST...
AT LEAST THROUGH FRIDAY OR SAT. MODELS HAVE VERY DIFFERENT
TIMING/TRACK/INTENSITY WITH SHRTWV LIFTING OUT OF THE SRN STREAM
FLOW OVER THE WEEKEND... THUS LITTLE CONFIDENCE IN THE POPS SATURDAY
BUT MAINTAINED FCST CONTINUITY BY FOLLOWING GFS SOLUTION WHICH
INDICATES A CHC OF RAIN/SNOW IN OUR AREA AROUND THIS PERIOD. IN THE
WAKE OF THIS SYSTEM... NRN STREAM TROF PROGGED TO STRENGTHEN/DIG SE
A BIT WHICH SHOULD ALLOW AIRMASS OVER THE WRN GRTLKS TO BECOME COLD
ENOUGH FOR SOME LAKE EFFECT SNOW SHOWERS BY LATE SUNDAY... THOUGH
DOESN`T LOOK LIKE A FAVORABLE SETUP FOR SGFNT LES ATTM WITH GFS
INDICATING FAIRLY LOW INVERSION HEIGHTS.
&&
.AVIATION...
CONDITIONS WILL CONTINUE TO GO DOWNHILL AT KFWA AS CONTINUED FLOW
OF MOISTURE OVER FRONTAL BOUNDARY TO THE SOUTH SETS THE STAGE FOR
PERIODS OF LIGHT PRECIP AND EXPANSIVE LOW CLOUDS. RADAR TRENDS
SUGGEST PRECIP STARTING TO MAKE A RUN FOR KFWA ATTM AND SPECIAL
JUST CAME IN AT KFWA FOR LIGHT RAIN STARTING AND DOWN TO 39.
TAMDAR SOUNDING OUT OF FORT WAYNE A FEW HOURS AGO SUPPORTS ALL
RAIN WITH A NEARLY 5000 FOOT DEEP LAYER OF TEMPS ABOVE FREEZING.
THAT BEING SAID...ONLY TALKING A FEW DEGREES ABOVE FREEZING AND SO
CLOSE ENOUGH TO KEEP MIX MENTION IN. HAVE KEPT WITH MIX MENTION
FOR SEVERAL HOURS AND WILL MONITOR FOR REMOVAL. LARGER AREA
WORKING ACROSS ILLINOIS WILL MOVE IN CLOSER TO 12Z AND BRING BEST
CHANCE FOR PRECIP. RAIN LOOKS TO SHIFT NORTH OF THE AREA POSSIBLY
BY LATE AFTERNOON BUT WILL QUICKLY MOVE BACK IN AND REMAIN IN
PLACE WITH IFR CIGS THROUGH 6Z.
MUCH MORE DIFFICULT FORECAST AT KSBN WHERE DRIER AIR HAS WORKED IN
AND ONLY MID/HIGH CLOUDS EXIST. LOWER CIGS NOT TOO FAR AWAY WIT
KASW HAVING A MVFR CIG ATTM. HAVE KEPT KSBN VFR THROUGH 17Z BUT
WOULD NOT BE SURPRISED IF AN AMENDMENT WILL BE NEEDED OVERNIGHT AS
MODELS GENERALLY TOO FAR SOUTH WITH CURRENT PRECIP AND CLOUD COVER
LAYOUT.
RAIN LOOKS TO EVENTUALLY MOVE IN THIS AFTERNOON WITH BETTER
CHANCES TOWARD THE END OF THE CURRENT FORECAST PERIOD. FURTHER
CHANGES WILL BE NEEDED TO KSBN OVER THE NEXT 6 HOURS AS EVOLUTION
OF PRECIP SHIELD AND EFFECTS OF DRY AIR BECOME BETTER ESTABLISHED.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...FISHER
LONG TERM...JT
AVIATION...FISHER
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1106 PM CST MON DEC 19 2011
.AVIATION...
A STORM SYSTEM WILL SLOWLY MOVE TOWARD IOWA AND ILLINOIS DURING
THE NEXT 24 HOURS. THIS STORM WILL SPREAD MVFR TO IFR CIGS AND
VISIBILITIES OVER SOUTHERN PARTS OF IOWA AND CENTRAL AND SOUTHERN
ILLINOIS. THIS WILL OCCUR MAINLY IN THE
FORM OF DRIZZLE AND LOW CLOUDS. SNOW RAIN MIXED ARE POSSIBLE
VERY LATE TONIGHT AT BRL...BUT THE TIMING OF THE ONSET IS VERY LOW
CONFIDENCE. THUS...IT MAY HOLD OFF UNTIL TOWARDS 15Z. NORTHEAST
WINDS AROUND 5 TO 8 KTS WILL BECOME LIGHT AND VARIABLE BY LATE
AFTERNOON TUESDAY. FROM LATE AFTERNOON THROUGH THE NIGHT TUESDAY
NIGHT...IFR LOW CLOUDS AND FOG ARE LIKELY...ALONG WITH DRIZZLE.
THIS MAY BRING A PERIOD OF LIFR CONDITIONS TO THE REGION.
&&
.PREV DISCUSSION... /ISSUED 315 PM CST MON DEC 19 2011/
SYNOPSIS...
12Z UA ANALYSIS HAD THE STORM SYSTEM DEVELOPING IN THE SOUTHERN
ROCKIES WITH A LLJ OF 40-50 KNOTS TRANSPORTING MOISTURE NORTH INTO
THE PLAINS AND OHIO VALLEY. AN 850MB COLD FRONT RAN FROM NORTHERN
LAKE HURON INTO NORTHEAST COLORADO. SATELLITE AND RADAR TRENDS
THROUGH MID AFTERNOON SHOWED INCREASING CLOUDS ACROSS THE AREA WITH
PRECIPITATION GENERALLY SOUTH OF A KSTJ TO KUIN LINE.
18Z SFC ANALYSIS HAD A COLD FRONT RUNNING FROM KOSC...TO KMCI...TO
AROUND KDHT. LOW PRESSURES FROM THE DEVELOPING STORM SYSTEM WERE
SOUTH OF KTCC AND NEAR KPPA. DEW POINTS WERE IN THE 40S JUST AHEAD
OF THE COLD FRONT INTO THE OHIO VALLEY WITH 50S CROSSING THE RED
RIVER INTO OKLAHOMA. DEW POINTS IN THE 20S AND 30S WERE ACROSS MUCH
OF THE NORTHERN/CENTRAL PLAINS AND UPPER MIDWEST.
SHORT TERM...TONIGHT AND TUESDAY...
THE MAIN QUESTION IS HOW LONG WILL THE DRY AIR KEEP THE
PRECIPITATION AT BAY TONIGHT INTO TUESDAY. BASED ON 12Z UA DATA...
THE WRF INITIALIZED A LITTLE BETTER THAN THE OTHER MODELS BASED ON
LOW LEVEL MOISTURE.
CONDENSATION PRESSURE DEFICITS ON EITHER STANDARD SURFACES OR THE
290-925K THETA SFC HAVE BEEN DEPICTING WELL THE AREAL COVERAGE OF
THE PRECIPITATION LATE THIS MORNING AND AFTERNOON. ALL MODELS HAVE
GENERALLY SHOWED THIS BUT THE RUC TRENDS HAVE DONE VERY WELL AND THE
RUC WILL BE USED FOR THE IMMEDIATE SHORT TERM.
BASED ON THE RUC CONDENSATION PRESSURE DEFICIT TRENDS...THE EARLY
EVENING WILL REMAIN DRY ACROSS THE ENTIRE AREA. BETWEEN 9 PM AND
MIDNIGHT PRECIPITATION WILL ADVECT/DEVELOP GENERALLY SOUTH OF A KOTM
TO KPIA LINE. FCST SOUNDINGS SHOW A TOP DOWN SATURATION TAKING PLACE
SO THERE WILL BE PLENTY OF EVAPORATIVE COOLING TAKING PLACE. THUS A
RAIN/SNOW MIX WILL DEVELOP THAT WILL LIKELY HAVE A BRIEF PERIOD OF
SLEET AS THE PRECIPITATION DEVELOPS. THERE IS A CONCERN BASED ON HOW
WARM IT HAS GOTTEN TODAY THAT PTYPE COULD BE MORE LIQUID THAN
FREEZING OR FROZEN.
AFTER MIDNIGHT...THE PRECIPITATION SHIELD WILL SLOWLY MOVE
NORTHWARD...REACHING A KOTM TO KGBG LINE AROUND 3 AM AND ROUGHLY A
KOOA TO KC75 LINE AROUND 12Z. THE I-80 CORRIDOR ON NORTH WILL REMAIN
DRY THROUGH SUNRISE. MINS TONIGHT WILL BE HIGHLY DEPENDENT ON CLOUD
COVER AND HOW THE PRECIPITATION SHIELD EVOLVES.
SNOW AMOUNTS SHOULD BE ONE HALF INCH OR LESS TONIGHT.
ON TUESDAY...THE PRECIPITATION SHIELD WILL CONTINUE MOVING NORTH AND
REACH I-80 ROUGHLY AROUND 9 AM AND SHOULD BE AROUND A VINTON TO MT
CARROLL LINE BY MID DAY. THE IMMEDIATE HWY 20 CORRIDOR IS EXPECTED
REMAIN DRY DURING THE MORNING HOURS. EVAPORATIVE COOLING WILL
CONTINUE TO PLAY SIGNIFICANTLY IN PTYPE WITH A RAIN/SNOW MIX ALONG
WITH A BRIEF PERIOD OF SLEET.
BY LATE MORNING AND INTO THE AFTERNOON HOURS...THE OVERALL FORCING
ACROSS THE AREA DECREASES. THE OVERALL PRECIPITATION INTENSITY WILL
LET UP AND A CHANGE OVER TO MAINLY RAIN IS EXPECTED EXCEPT ACROSS
ROUGHLY THE NORTHWEST THIRD OR SO OF THE CWFA WHERE A MIX IS STILL
EXPECTED. THE RAIN MAY STOP OR GO TO MORE DRIZZLE DURING THE
AFTERNOON HOURS.
SNOW AMOUNTS ON TUESDAY SHOULD BE ONE HALF INCH OR LESS. ..08..
LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
TUESDAY NIGHT AND WEDNESDAY...LATEST 12Z RUNS HAVE SHIFTED SLIGHTLY
BACK SOUTHWARD WITH RESPECT TO MAIN SFC LOW AND MID LEVEL
PROPAGATION PATHS LATER TUE THROUGH WED. WILL SIDE THE NEW 12Z RUN
ECMWF AND NAM WHICH ARE IN GOOD AGREEMENT WITH THEIR MASS FIELDS
WITH EACH OTHER AND THERE SOLUTIONS ARE IN THE MIDDLE OF THE ROAD OF
THE ENSEMBLES OF THESE FEATURES. THESE ACCEPTED SOLUTIONS SUGGEST
THAT THE SFC LOW WILL BE ACRS FAR SOUTHWEST MO AT 00Z WED...AND MOVE
NORTHEASTWARD TO THE EAST CENTRAL IL/WEST CENTRAL INDIANA BORDER
REGION BY 12Z WED WITH EYES ON THE WESTERN BASIN OF LK ERIE BY
MIDDAY WED. UPPER LOW TILTED TO THE NORTHWEST OF THE LLVL CYCLONE
WILL STILL LOOK TO PROGRESS ACRS THE SOUTHWEST HALF OF THE CWA BY
WED MORNING STILL IN A CLOSED FASHION AND THEN LOOK TO OPEN UP ON
THE WAY TO OVER THE SOUTH HALF OF LK MI BY WED AFTERNOON. ACCEPTED
THERMAL PROFILES SUGGEST LIGHT RAIN ACRS THE SOUTHEAST HALF OF THE
DVN CWA TUE EVENING WITH SOME SLEET POSSIBLY MIXED IN THE NORTHERN
FRINGE OF THE RAIN AT SFC BAND UP ALONG THE SOUTHERN I80 CORRIDOR.
WITH THE MODELS STILL SUGGESTING THE MAIN THRUST OF WARM MOIST
CONVEYOR SHUNTED OFF TO THE EAST AND SOUTHEAST OF THE AREA BY LATE
TUE...THE APPROACHING UPPER LOW WILL ONLY HAVE TO WORK WITH
SECONDARY MOISTURE FEED AND THUS ONLY A LIGHT PRECIP EVENT STILL
LOOKS ON TAP FOR TUE NIGHT FOR THE MAJORITY OF THE DVN CWA. THERMAL
PROFILES TUE EVENING ALONG AND NORTH OF A LINE FROM MT CARROLL IL...
TO CID AND SOUTHWEST OF IOWA CITY SUGGEST LIGHT SNOW AND SLEET IN
THESE AREAS TUE EVENING...AND ONLY FLURRIES ALONG AND NORTH OF THE
HWY 20 CORRIDOR. SNOW AND SLEET ACCUMS UNDER AN INCH TUE EVENING IN
THESE AREAS...BUT A CHANCE OF A NARROW SWATH OF 1-2 INCHES OF
SNOW ACCUM ON THE NORTHERN FRINGE OF RAIN/SLEET TRANSITION TO SNOW
BAND FROM WILLIAMSBURG TO CLINTON IA BY MID TUE EVENING. THEN IN-
WRAPPING MID LEVEL DRYING SHOULD SWITCH ALMOST ALL THE PRECIP TO
MAINLY DRIZZLE OR FREEZING DRIZZLE FROM MID EVENING THROUGH 12 AM-1
AM CST. AREAS OF TEMPORARY DENSE FOG POSSIBLE TOO BUT WILL LEAVE
OUT MENTION AT THIS POINT. THEN WITH THE APPROACH OF THE MID LEVEL
LOW AFTER MIDNIGHT...THE FCST SOUNDINGS SATURATE DEEPER AGAIN AND
SUPPORT A BAND OF SECONDARY DEF ZONE RAINS CLIPPING THE SOUTHEAST
THIRD OF THE CWA INTO EARLY WED MORNING WITH UP TO .3 OR .4 INCHES OF
RAIN POSSIBLE BY 8 AM CST WED. THE WESTERN FRINGE OF THIS DEF ZONE
RAIN MAY MIX WITH SNOW BY WED MORNING WITH LIGHT SLUSHY SNOW ACCUMS
UP TO AN INCH. FURTHER NORTH AND WEST OVER THE REST OF THE CWA...
LIGHT DRIZZLE OR FREEZING DRIZZLE DEPENDING ON THE SFC TEMPS WILL
LOOK TO TOP-DOWN COOL AND SATURATE INTO ALL LIGHT SNOW PARAMETERS
AFTER 1 AM WITH LIGHT ADDITIONAL SNOW ACCUMS POSSIBLE UP TO AN INCH
BY WED MORNING WHEN THE PRECIP WILL BE ON THE MOVE OUT OF THE LOCAL
FCST AREA. WILL STILL HAVE TO BE WARY OF SOME BANDED SNOWS OF AT
LEAST 1-2 INCHES AS THE UPPER LOW APPROACHES LATE TUE NIGHT IF
DYNAMICAL/TOP DOWN COOLING OCCURS QUICKER THAN CURRENTLY ANTICIPATED.
THERE STILL MAY BE A NEED FOR A WINTER WEATHER ADVISORY TUE NIGHT FOR
THE ROUNDS OF LIGHT FREEZING RAIN...FREEZING DRIZZLE...SNOW AND SLEET
MIX WITH AREAS ALONG AND NORTH OF I80 THE MOST LIKELY TARGET. THE
REST OF WED AND WED NIGHT SHOULD HAVE NO REAL WX MAKERS AND BE QUIET.
THURSDAY THROUGH FRIDAY...DEPENDING ON WHAT LIES IN THE WAKE OF THE
MID WEEK SYSTEM STREAM FLOW AND BAROCLINICITY-WISE...A RE-LOADING
SOUTHWESTERN CONUS TROF AND ACTIVE NORTHERN STREAM ACRS THE WEST
HALF OF THE CONUS HAVE ALL THE MEDIUM RANGE MODELS A FLUTTER THIS
PERIOD. MUCH UNCERTAINTY OF COURSE...BUT SIGNALS OF SOUTH-WESTERLIES
IN THE SOUTHERN STREAM REORGANIZING SOUTH AND SOUTHWEST OF THE
LOCAL AREA JUST SOUTH OF CONFLUENT FLOW MAY ALLOW SOME ELEVATED
FRONTOGENETICAL FORCING ALONG AND BEHIND A LLVL FRONT GETTING
ALIGNED PARALLEL TO THIS MEAN FLOW TO GENERATE SOME LIGHT SNOW OR
FLURRIES ACRS THE CWA EITHER LATE THU OR THU NIGHT INTO FRI
MORNING. AT THIS POINT WITH THE DRY LOOKING VERTICAL PROFILES...JUST
A DUSTING TO UNDER AN INCH WOULD ALL THAT WOULD BE POSSIBLE BY FRI
MORNING AND MAINLY FROM IOWA CITY TO FREEPORT IL AND NORTHWARD.
THE 12Z RUN UKMET...GEM AN GFS ARE EITHER DRY OR JUST HAVE FLURRIES
FOR THU NIGHT. LONGER RANGE SIGNALS SUGGEST PHASING ISSUES A PLENTY
AS THE DIGGING NORTHERN STREAM UPPER TROF OVER CENTRAL CANADA TRIES
TO INTERACT WITH THE SOUTHWEST PLAINS TROFFINESS. THE MAJORITY OF
THE LONGER RANGE MODELS HANDLE THIS PROCESS IN A WAY THAT ANY
SOUTHERN STREAM WX MAKER AND IT/S ASSOCIATED PRECIP REMAINS ALONG
OR SOUTH OF THE DVN CWA FROM FRI INTO SAT. BUT THE 12Z GFS MUCH
MORE OMINOUS AND DEVELOPED UPSTREAM. IT PHASES THE STREAMS IN A WAY
THAT A STORM SYSTEM WITH AT LEAST HIGHER END ADVISORY SNOWS/2-5+
INCHES IMPACTS THE ENTIRE CWA FRI NIGHT INTO SAT MORNING. WILL WATCH
FURTHER TRENDS OF COURSE WITH ADDITIONAL RUNS OVER THE NEXT 24-48
HRS. WILL GO WITH SEASONABLE TEMPS FOR THU THROUGH FRI FOR NOW.
SATURDAY THROUGH MONDAY...ENSEMBLES AND TELECONNECTIONS OVER THE
HOLIDAY WEEKEND SUGGEST SOME AO/ARCTIC OSCILLATION INFLUENCE AS
GENERAL L/W TROFFINESS TRIES TO ESTABLISH THIS PERIOD AND INTO EARLY
NEXT WEEK ACRS THE UPPER MIDWEST AND GRT LKS. THIS PERIOD ALSO LOOKS
GENERALLY DRY AFTER SAT WITH SOME RE-ENFORCING COOL SHOTS OUT OF
CANADA POSSIBLE FOR SEASONABLE OR SOMEWHAT BELOW TEMPS INTO NEXT
MONDAY. CAN/T RULE OUT SOME FLURRIES ON LEADING EDGES OF COOL DUMPS
OR WEAK WAVES EMBEDDED IN NORTHWESTERLY CYCLONIC FLOW...BUT WILL GO
MAINLY DRY FOR NOW. ..12..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
319 PM CST TUE DEC 20 2011
.DISCUSSION...
SHORT RANGE (TONIGHT AND WEDNESDAY)...
20Z WATER VAPOR IMAGERY AND ASSOCIATED RUC ANALYSIS CONTINUES TO
SHOW THE 500 MB TROUGH MOVING SLOWLY TO THE NORTHEAST ACROSS EASTERN
KANSAS. CURRENTLY IT IS SITTING OVER SOUTH CENTRAL KANSAS AND SHOULD
PUSH THROUGH THE AREA BY TONIGHT. RADAR TRENDS SHOW PRECIPITATION
ENDING ACROSS CENTRAL KANSAS...AND THIS TREND SHOULD CONTINUE
THROUGH THE REST OF THE EVENING AS THE BETTER LIFT ASSOCIATED WITH
THIS SYSTEM PUSHES EAST. ANOTHER SHIELD OF LIGHT PRECIPITATION IS
MOVING NORTHEASTWARD ALONG THE KANSAS TURNPIKE AND WILL LIKELY BRING
ANOTHER ROUND OF MIXED PRECIPITATION TO AREAS EAST OF THE TURNPIKE.
CURRENTLY KUKL INDICATES 36 DEGREES AS DOES KOJC...SO EXPECT THE
BULK OF THE REMAINING PRECIP TO FALL IN THE FORM OF A RAIN/SNOW MIX
FOR THE REMAINDER OF THE EVENING ALONG THE NEWLY FORMED DEFORMATION
BAND. EXPECT THE BEST LIFT WITH THIS ROUND OF SHOWERS TO MOVE OFF TO
THE EAST BY LATE THIS EVENING THUS ENDING ALL PRECIP FOR OUR
FORECAST AREA. SHOULD THERE BE ANY SNOW ASSOCIATED WITH THIS
EVENINGS PRECIP DON`T EXPECT MUCH MORE THAN A DUSTING OF SNOW ON
GRASSY SURFACES. SINCE ROADWAYS ARE WET FROM THE ONGOING PRECIP AND
OVERNIGHT LOWS WILL DROP INTO THE TEENS TO TWENTIES THERE IS A
POTENTIAL FOR SLICK SPOTS ON ROADWAYS...ESPECIALLY ONCE TEMPS DIP
BELOW 32 DEGREES. SKIES WILL GRADUALLY CLEAR BEHIND THE DEPARTING
SYSTEM...FIRST ACROSS CENTRAL AND NORTH CENTRAL KANSAS...THEN BY 12Z
ACROSS FAR EASTERN KANSAS. AS A RESULT OF THE NEWLY FALLEN SNOW
ACROSS C/NC KANSAS AND THE CLEARING SKIES EXPECT LOW TEMPS TO REACH
INTO THE MID TEENS TONIGHT...AND INTO THE LOWER TO MID 20S FURTHER
EAST WHERE NO SNOW FELL AND SKIES WILL BE SLOWER TO CLEAR. WEDNESDAY
WILL BRING A MILD DAY ACROSS NORTHEAST KANSAS AS TEMPS WILL REACH
INTO THE LOWER TO MID 40S WHERE NO NEW SNOW FELL...BUT WILL ONLY
REACH THE MID 30S OVER THE SNOW PACK IN C/NC KANSAS. JL
THURS-TUES...AFTER A BREAK FROM THE CLOUDS AND
PRECIPITATION...THE NEXT UPPER TROF APPROACHES THE STATE FROM THE
NORTH AND NORTHWEST THURSDAY AND THROUGH FRIDAY. AT THIS TIME MAIN
PIECE OF ENERGY AND DYNAMICS STAYS TO THE WEST...LEAVING THE LEAD
SHEAR VORTICITY AHEAD OF THE NORTHERN WAVE TO SLIDE ACROSS KANSAS.
ENOUGH LIFT WITH THIS AND COUPLED WITH SOME FRONTOGENETIC FORCING
TO BRING A CHANCE OF SNOW THROUGH FRIDAY. NOT MUCH MOISTURE TO
WORK WITH SO DONT EXPECT MUCH FOR ACCUMULATIONS DESPITE HIGHER
SNOW TO LIQUID RATIOS THAN THE PREVIOUS STORM. STILL VARIATIONS IN
THE GUIDANCE AS TO HOW TO HANDLE THE WESTERN PORTION OF THIS
SYSTEM WITH EC/NAM TRENDING A SOUTHWARD SLOWER TRACK AND GFS MORE
PROGRESSIVE ACROSS AND OUT OF OUR AREA. EC IS THEREFORE COOLER IN
THE EXTENDED WHILE GFS IS WARMER IN MORE WESTERLY FLOW. HAVE DRY
CONDITIONS BEYOND FRIDAY WITH A SLOW WARMING TREND...AND WILL HAVE
TO WATCH EVOLUTION OF THAT UPPER PATTERN FOR CHANGES. 67
&&
.AVIATION...
IFR CONDITIONS EXPECTED TO DOMINATE FOR MUCH OF THE DAY INTO THE
OVERNIGHT WITH BRIEF PERIODS OF LIFR OR MVFR POSSIBLE. SNOW WILL
CONTINUE AT KMHK FOR MUCH OF THE AFTERNOON WITH DRIZZLE EXPECTED
TO CONTINUE AT KTOP AND KFOE. FROZEN PRECIPITATION MAY MIX IN
BRIEFLY AT TIMES AT KTOP AND KFOE BUT TEMPERATURES AT THE SURFACE
SHOULD REMAIN ABOVE FREEZING AS PRECIPITATION OCCURS. PRECIP. WILL
COME TO AN END AROUND 00Z WITH CEILINGS IMPROVING TO VFR BY 10Z
TOMORROW.
ANDERSON
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1136 AM CST TUE DEC 20 2011
.AVIATION...
FOR THE 18Z TAF ISSUANCE...
LIGHT SNOW OR BLOWING SNOW WILL BE POSSIBLE OVER THE NEXT COUPLE
OF HOURS AS THE STORM SYSTEM MOVES TO THE EAST. OTHERWISE EXPECT
MOSTLY CLOUDY SKIES AOA030 UNTIL AROUND 20Z. THEREAFTER...SKIES
SHOULD CLEAR FROM WEST TO EAST AND BECOME MOSTLY CLEAR BY THIS
EVENING. NORTHERLY WINDS AROUND 20 KNOTS EARLY THIS AFTERNOON
SHOULD SHIFT TO THE NORTHWEST AND DECREASE TO AROUND 12 KNOTS LATE
THIS AFTERNOON. WINDS ARE THEN ANTICIPATED TO BECOME LIGHT AND
VARIABLE THIS EVENING INTO THE OVERNIGHT HOURS.
&&
.PREV DISCUSSION... /ISSUED 621 AM CST TUE DEC 20 2011/
UPDATE...
AVIATION /FOR THE 12Z TAF ISSUANCE/
IFR CONDITIONS WILL PERSIST THROUGH THE NEXT SEVERAL HOURS BASED ON
BOTH LOW CEILINGS AND VISIBILITIES REDUCED IN SNOW. SOME IMPROVEMENT TO
THE MVFR RANGE IS POSSIBLE BY AROUND 18 UTC AS THE UPPER LOW LIFTS
FARTHER INTO EASTERN KANSAS. WINDS WILL ALSO BE DIMINISHING INTO HE
15 TO 25 MPH RANGE LATER IN THE DAY, SUPPORTED BY LOCAL GFS MOS
GUIDANCE.
PREV DISCUSSION... /ISSUED 232 AM CST TUE DEC 20 2011/
DISCUSSION...
DAYS 1-2...
00Z TUESDAY UPPER AIR ANALYSIS PLACED A 850MB AND 700MB
BAROCLINIC ZONE FROM JUST NORTH OF ELKHART TO NEAR HAYS. THE UPPER
LOW WAS POSITIONED NEAR AMARILLO. STILL OBSERVING GOOD MOISTURE
AND WARM AIR ADVECTION ACROSS CENTRAL AND PARTS OF SOUTHWEST
KANSAS AS OUR UPPER LOW MOVES TOWARDS NORTHWEST OKLAHOMA EARLIER
THIS MORNING. JET STREAK DYNAMICS NEAR THE LEFT EXIT REGION OF
250MB JET WILL BE LOCATED ACROSS PORTIONS OF NORTH CENTRAL KANSAS
EARLY THIS MORNING SO AT THIS TIME BASED ON THE LOCATION OF THE
MID LEVEL FRONTOGENESIS IT WOULD APPEAR THAT PERIODS OF MODERATE
SNOW STILL WILL BE POSSIBLE IN AREAS ALONG AND NORTH OF HIGHWAY
156. THE NAM, RUC, AND HRRR WERE ALSO ALL IN DECENT AGREEMENT WITH
PRECIPITATION CONTINUING THROUGH THE EARLY MORNING HOURS IN THIS
AREA SO INITIAL THOUGHTS WILL BE TO FOLLOW THE GENERAL TRENDS OF
THE NAM,RUC AND HRRR OVER THE NEXT 6-9 HOURS. FURTHER WEST NEAR
THE COLORADO BORDER AND AREAS SOUTH NEAR THE OKLAHOMA BORDER THE
PRECIPITATION SHOULD BE STARTING TO TAPER OFF.
WINDS STILL WILL BE AN ISSUE EARLY TUESDAY MORNING GIVEN THE
LOCATION OF THE PRESSURE GRADIENT NORTHWEST OF THE SURFACE LOW
ALONG WITH THE CURRENT VAD WINDS AND PROFILER DATA. ALTHOUGH WIND
SPEEDS ARE NOT EXPECTED TO BE AS STRONG AS YESTERDAY, IT DOES
APPEAR THAT SOME REDUCED VISIBILITIES WILL CONTINUE IN THE
BLIZZARD WARNING AREA. LOCATIONS SOUTH OF HIGHWAY 156 WILL SEE
IMPROVING CONDITIONS EARLY THIS MORNING BUT GIVEN ONGOING SNOW,
BLOWING SNOW AND CURRENT CONDITIONS HAVE DECIDED NOT TO BEGIN
TRIMMING THE BLIZZARD WARNING YET.
BY MID DAY ISENTROPIC DOWN GLIDE WILL BEGIN TO DEVELOP WEST OF
OUR UPPER LOW WHICH WILL BE LOCATED NEAR SOUTH CENTRAL KANSAS. A
SURFACE HIGH WILL THEN BEGIN TO BUILD INTO WESTERN KANSAS FROM THE
NORTHWEST. MODEL SOUNDINGS CONTINUE TO SUGGEST TO CLOUD COVER
THROUGH MUCH OF THE DAY SO BASED ON THIS AND COLD AIR ADVECTION
OCCURRING OVER THE SNOW PACK WILL UNDERCUT GUIDANCE FOR HIGHS
TODAY.
TONIGHT SKIES WILL CLEAR AS WINDS DECREASE TO LESS THAN 10KTS.
WINDS NOT IDEAL FOR A GREAT NIGHT OF RADIATION COOLING BUT
CONDITIONS STILL FAVOR UNDERCUTTING CURRENT GUIDANCE AND STAYING
CLOSE TO THE CURRENT FORECAST OF WITH LOWS EARLY WEDNESDAY MORNING
IN THE SINGLE DIGITS.
WEDNESDAY SHOULD BE SUNNY AS WESTERLY DOWNSLOPE FLOW IMPROVES
ACROSS WESTERN KANSAS. DECENT WARMING OCCURS ABOVE THE SURFACE BUT
BASED ON SNOWFALL EXPECTED ACROSS SOUTHWEST KANSAS FEEL MUCH OF
THE WARMING WILL GO INTO SNOW MELT. AS A RESULT WILL UNDERCUT
GUIDANCE ONCE AGAIN AND FAVOR THE PREVIOUS FORECAST WHICH IS CLOSE
TO 10F COOLER THAN THE COOLEST GUIDANCE.
DAYS 3-7...
LONG TERM /THURSDAY THROUGH MONDAY/
A PROGRESSIVE LONGWAVE PATTERN IS IN STORE FOR THE EXTENDED PERIOD,
WITH AT LEAST A COUPLE OF ADDITIONAL COLD FRONTAL PASSAGES ACROSS
THE CENTRAL HIGH PLAINS.
AFTER THE MAJOR SYSTEM THAT IS CAUSING THE BLIZZARD RIGHT NOW OVER
WESTERN KANSAS LIFTS EASTWARD INTO THE UPPER MIDWEST ON TUESDAY
NIGHT AND WEDNESDAY, ANOTHER PAIR OF SHARP MID LEVEL IMPULSES WILL
BE ROTATING THROUGH THE MEAN TROUGH. THE FIRST WILL ROTATE SOUTHWARD
FROM THE NORTHERN ROCKIES AND THE SECOND, JUST AHEAD OF THE NORTHERN
STREAM SHORTWAVE, FROM THE DESERT SOUTHWEST. FROM A LOOK AT THE GFS
AND ECMWF THE TWO WAVES APPEAR TO ENHANCE THE MID LEVEL BAROCLINICITY
ACROSS WESTERN KANSAS ON THURSDAY, WHILE A SURFACE COLD FRONT DIVES
SOUTHWARD ACROSS THE AREA EARLY IN THE DAY. BOTH MODELS HAVE BEEN
CONSISTENT IN PRODUCING BETWEEN 0.05" AND 0.15" OF PRECIPITATION
TIED TO THE LEADING SHORTWAVE, WITH POST SURFACE FRONT QPF. QUITE COLD
850 MB AIR ABOUT -5 T0 -8 SHOULD ENSURE THE PRECIPITATION TYPE WOULD
BE SNOW, AND AS A RESULT, IT IS POSSIBLE CENTRAL KANSAS AND MUCH OF
SOUTHWEST WILL BE EXPERIENCING ADDITIONAL, BUT PROBABLY MINOR
ACCUMULATIONS ON THURSDAY AFTERNOON. THE REMAINDER OF THE FORECAST
DOES LOOK DRY, BUT COLD. THE SECOND OF THESE UPPER SHORTWAVES
ROTATES THROUGH THE MEAN TROUGH ON FRIDAY AND SURFACE WINDS BEGIN TO
WEAKEN AS THE UPPER LEVEL HEIGHT FIELDS BECOME PARALLEL TO THE
MOUNTAIN BARRIER. FRIDAY WILL REMAIN COLD WITH VERY WEAK SURFACE
WINDS OVER THE AREA, BUT THE 850 MB TEMPERATURES BEGIN TO INCREASE
WITH STRONGER DOWNSLOPE FLOW OVER THE SNOWPACK. MODELS SEEM TO BUMP
MAXIMUM TEMPERATURES ABOUT 5 DEGREES ON SATURDAY AFTERNOON, BUT THIS
IS STILL WELL BELOW NORMAL. THE MODELS CONTINUE THOUGH THE END OF
THE WEEKEND DRY AND COOL WITH DEEP NORTHWEST FLOW OVER THE HIGH
PLAINS REGION INTO MONDAY.
AVIATION...
FOR THE 06Z TAF ISSUANCE... BLIZZARD OR NEAR BLIZZARD CONDITIONS
WILL CONTINUE THROUGH EARLY TUESDAY MORNING WITH THE DOMINANT
FLIGHT CATEGORY BEING VLIFR AT GCK AND DDC THROUGH MUCH OF THE
NIGHT TOWARD DAYBREAK. WIND SPEEDS WILL GRADUALLY DECREASE BY
DAYBREAK WITH VISIBILITIES IMPROVING AS WELL. AFTER THE SNOW
CEASES...LOW OVERCAST WILL LIKELY PERSIST THROUGH AT LEAST THE
EARLY AFTERNOON BEFORE CLEARING TAKES PLACE AND VFR CONDITIONS
RESUME. -UMSCHEID
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 9 30 14 29 / 0 0 10 60
GCK 6 29 13 27 / 0 0 10 50
EHA 5 29 13 27 / 0 0 10 50
LBL 6 30 15 29 / 0 0 10 50
HYS 6 30 15 28 / 0 0 20 70
P28 14 38 23 33 / 10 0 10 50
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN12/42/42
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
621 AM CST TUE DEC 20 2011
.UPDATE...
.AVIATION /FOR THE 12Z TAF ISSUANCE/
IFR CONDITIONS WILL PERSIST THROUGH THE NEXT SEVERAL HOURS BASED ON
BOTH LOW CEILINGS AND VISIBILITIES REDUCED IN SNOW. SOME IMPROVEMENT TO
THE MVFR RANGE IS POSSIBLE BY AROUND 18 UTC AS THE UPPER LOW LIFTS
FARTHER INTO EASTERN KANSAS. WINDS WILL ALSO BE DIMINISHING INTO HE
15 TO 25 MPH RANGE LATER IN THE DAY, SUPPORTED BY LOCAL GFS MOS
GUIDANCE.
&&
.PREV DISCUSSION... /ISSUED 232 AM CST TUE DEC 20 2011/
DISCUSSION...
DAYS 1-2...
00Z TUESDAY UPPER AIR ANALYSIS PLACED A 850MB AND 700MB
BAROCLINIC ZONE FROM JUST NORTH OF ELKHART TO NEAR HAYS. THE UPPER
LOW WAS POSITIONED NEAR AMARILLO. STILL OBSERVING GOOD MOISTURE
AND WARM AIR ADVECTION ACROSS CENTRAL AND PARTS OF SOUTHWEST
KANSAS AS OUR UPPER LOW MOVES TOWARDS NORTHWEST OKLAHOMA EARLIER
THIS MORNING. JET STREAK DYNAMICS NEAR THE LEFT EXIT REGION OF
250MB JET WILL BE LOCATED ACROSS PORTIONS OF NORTH CENTRAL KANSAS
EARLY THIS MORNING SO AT THIS TIME BASED ON THE LOCATION OF THE
MID LEVEL FRONTOGENESIS IT WOULD APPEAR THAT PERIODS OF MODERATE
SNOW STILL WILL BE POSSIBLE IN AREAS ALONG AND NORTH OF HIGHWAY
156. THE NAM, RUC, AND HRRR WERE ALSO ALL IN DECENT AGREEMENT WITH
PRECIPITATION CONTINUING THROUGH THE EARLY MORNING HOURS IN THIS
AREA SO INITIAL THOUGHTS WILL BE TO FOLLOW THE GENERAL TRENDS OF
THE NAM,RUC AND HRRR OVER THE NEXT 6-9 HOURS. FURTHER WEST NEAR
THE COLORADO BORDER AND AREAS SOUTH NEAR THE OKLAHOMA BORDER THE
PRECIPITATION SHOULD BE STARTING TO TAPER OFF.
WINDS STILL WILL BE AN ISSUE EARLY TUESDAY MORNING GIVEN THE
LOCATION OF THE PRESSURE GRADIENT NORTHWEST OF THE SURFACE LOW
ALONG WITH THE CURRENT VAD WINDS AND PROFILER DATA. ALTHOUGH WIND
SPEEDS ARE NOT EXPECTED TO BE AS STRONG AS YESTERDAY, IT DOES
APPEAR THAT SOME REDUCED VISIBILITIES WILL CONTINUE IN THE
BLIZZARD WARNING AREA. LOCATIONS SOUTH OF HIGHWAY 156 WILL SEE
IMPROVING CONDITIONS EARLY THIS MORNING BUT GIVEN ONGOING SNOW,
BLOWING SNOW AND CURRENT CONDITIONS HAVE DECIDED NOT TO BEGIN
TRIMMING THE BLIZZARD WARNING YET.
BY MID DAY ISENTROPIC DOWN GLIDE WILL BEGIN TO DEVELOP WEST OF
OUR UPPER LOW WHICH WILL BE LOCATED NEAR SOUTH CENTRAL KANSAS. A
SURFACE HIGH WILL THEN BEGIN TO BUILD INTO WESTERN KANSAS FROM THE
NORTHWEST. MODEL SOUNDINGS CONTINUE TO SUGGEST TO CLOUD COVER
THROUGH MUCH OF THE DAY SO BASED ON THIS AND COLD AIR ADVECTION
OCCURRING OVER THE SNOW PACK WILL UNDERCUT GUIDANCE FOR HIGHS
TODAY.
TONIGHT SKIES WILL CLEAR AS WINDS DECREASE TO LESS THAN 10KTS.
WINDS NOT IDEAL FOR A GREAT NIGHT OF RADIATION COOLING BUT
CONDITIONS STILL FAVOR UNDERCUTTING CURRENT GUIDANCE AND STAYING
CLOSE TO THE CURRENT FORECAST OF WITH LOWS EARLY WEDNESDAY MORNING
IN THE SINGLE DIGITS.
WEDNESDAY SHOULD BE SUNNY AS WESTERLY DOWNSLOPE FLOW IMPROVES
ACROSS WESTERN KANSAS. DECENT WARMING OCCURS ABOVE THE SURFACE BUT
BASED ON SNOWFALL EXPECTED ACROSS SOUTHWEST KANSAS FEEL MUCH OF
THE WARMING WILL GO INTO SNOW MELT. AS A RESULT WILL UNDERCUT
GUIDANCE ONCE AGAIN AND FAVOR THE PREVIOUS FORECAST WHICH IS CLOSE
TO 10F COOLER THAN THE COOLEST GUIDANCE.
DAYS 3-7...
LONG TERM /THURSDAY THROUGH MONDAY/
A PROGRESSIVE LONGWAVE PATTERN IS IN STORE FOR THE EXTENDED PERIOD,
WITH AT LEAST A COUPLE OF ADDITIONAL COLD FRONTAL PASSAGES ACROSS
THE CENTRAL HIGH PLAINS.
AFTER THE MAJOR SYSTEM THAT IS CAUSING THE BLIZZARD RIGHT NOW OVER
WESTERN KANSAS LIFTS EASTWARD INTO THE UPPER MIDWEST ON TUESDAY
NIGHT AND WEDNESDAY, ANOTHER PAIR OF SHARP MID LEVEL IMPULSES WILL
BE ROTATING THROUGH THE MEAN TROUGH. THE FIRST WILL ROTATE SOUTHWARD
FROM THE NORTHERN ROCKIES AND THE SECOND, JUST AHEAD OF THE NORTHERN
STREAM SHORTWAVE, FROM THE DESERT SOUTHWEST. FROM A LOOK AT THE GFS
AND ECMWF THE TWO WAVES APPEAR TO ENHANCE THE MID LEVEL BAROCLINICITY
ACROSS WESTERN KANSAS ON THURSDAY, WHILE A SURFACE COLD FRONT DIVES
SOUTHWARD ACROSS THE AREA EARLY IN THE DAY. BOTH MODELS HAVE BEEN
CONSISTENT IN PRODUCING BETWEEN 0.05" AND 0.15" OF PRECIPITATION
TIED TO THE LEADING SHORTWAVE, WITH POST SURFACE FRONT QPF. QUITE COLD
850 MB AIR ABOUT -5 T0 -8 SHOULD ENSURE THE PRECIPITATION TYPE WOULD
BE SNOW, AND AS A RESULT, IT IS POSSIBLE CENTRAL KANSAS AND MUCH OF
SOUTHWEST WILL BE EXPERIENCING ADDITIONAL, BUT PROBABLY MINOR
ACCUMULATIONS ON THURSDAY AFTERNOON. THE REMAINDER OF THE FORECAST
DOES LOOK DRY, BUT COLD. THE SECOND OF THESE UPPER SHORTWAVES
ROTATES THROUGH THE MEAN TROUGH ON FRIDAY AND SURFACE WINDS BEGIN TO
WEAKEN AS THE UPPER LEVEL HEIGHT FIELDS BECOME PARALLEL TO THE
MOUNTAIN BARRIER. FRIDAY WILL REMAIN COLD WITH VERY WEAK SURFACE
WINDS OVER THE AREA, BUT THE 850 MB TEMPERATURES BEGIN TO INCREASE
WITH STRONGER DOWNSLOPE FLOW OVER THE SNOWPACK. MODELS SEEM TO BUMP
MAXIMUM TEMPERATURES ABOUT 5 DEGREES ON SATURDAY AFTERNOON, BUT THIS
IS STILL WELL BELOW NORMAL. THE MODELS CONTINUE THOUGH THE END OF
THE WEEKEND DRY AND COOL WITH DEEP NORTHWEST FLOW OVER THE HIGH
PLAINS REGION INTO MONDAY.
AVIATION...
FOR THE 06Z TAF ISSUANCE... BLIZZARD OR NEAR BLIZZARD CONDITIONS
WILL CONTINUE THROUGH EARLY TUESDAY MORNING WITH THE DOMINANT
FLIGHT CATEGORY BEING VLIFR AT GCK AND DDC THROUGH MUCH OF THE
NIGHT TOWARD DAYBREAK. WIND SPEEDS WILL GRADUALLY DECREASE BY
DAYBREAK WITH VISIBILITIES IMPROVING AS WELL. AFTER THE SNOW
CEASES...LOW OVERCAST WILL LIKELY PERSIST THROUGH AT LEAST THE
EARLY AFTERNOON BEFORE CLEARING TAKES PLACE AND VFR CONDITIONS
RESUME. -UMSCHEID
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 27 9 30 14 / 90 0 0 10
GCK 28 6 29 13 / 90 0 0 10
EHA 27 5 29 13 / 50 0 0 10
LBL 27 6 30 15 / 50 0 0 10
HYS 29 6 30 15 / 100 0 0 20
P28 32 14 38 23 / 70 10 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
BLIZZARD WARNING UNTIL NOON CST /11 AM MST/ TODAY FOR KSZ030-031-
043>046-061>066-074>080-084>088.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR KSZ081-089-090.
&&
$$
FN99/99
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
232 AM CST TUE DEC 20 2011
.DISCUSSION...
DAYS 1-2...
00Z TUESDAY UPPER AIR ANALYSIS PLACED A 850MB AND 700MB
BAROCLINIC ZONE FROM JUST NORTH OF ELKHART TO NEAR HAYS. THE UPPER
LOW WAS POSITIONED NEAR AMARILLO. STILL OBSERVING GOOD MOISTURE
AND WARM AIR ADVECTION ACROSS CENTRAL AND PARTS OF SOUTHWEST
KANSAS AS OUR UPPER LOW MOVES TOWARDS NORTHWEST OKLAHOMA EARLIER
THIS MORNING. JET STREAK DYNAMICS NEAR THE LEFT EXIT REGION OF
250MB JET WILL BE LOCATED ACROSS PORTIONS OF NORTH CENTRAL KANSAS
EARLY THIS MORNING SO AT THIS TIME BASED ON THE LOCATION OF THE
MID LEVEL FRONTOGENESIS IT WOULD APPEAR THAT PERIODS OF MODERATE
SNOW STILL WILL BE POSSIBLE IN AREAS ALONG AND NORTH OF HIGHWAY
156. THE NAM, RUC, AND HRRR WERE ALSO ALL IN DECENT AGREEMENT WITH
PRECIPITATION CONTINUING THROUGH THE EARLY MORNING HOURS IN THIS
AREA SO INITIAL THOUGHTS WILL BE TO FOLLOW THE GENERAL TRENDS OF
THE NAM,RUC AND HRRR OVER THE NEXT 6-9 HOURS. FURTHER WEST NEAR
THE COLORADO BORDER AND AREAS SOUTH NEAR THE OKLAHOMA BORDER THE
PRECIPITATION SHOULD BE STARTING TO TAPER OFF.
WINDS STILL WILL BE AN ISSUE EARLY TUESDAY MORNING GIVEN THE
LOCATION OF THE PRESSURE GRADIENT NORTHWEST OF THE SURFACE LOW
ALONG WITH THE CURRENT VAD WINDS AND PROFILER DATA. ALTHOUGH WIND
SPEEDS ARE NOT EXPECTED TO BE AS STRONG AS YESTERDAY, IT DOES
APPEAR THAT SOME REDUCED VISIBILITIES WILL CONTINUE IN THE
BLIZZARD WARNING AREA. LOCATIONS SOUTH OF HIGHWAY 156 WILL SEE
IMPROVING CONDITIONS EARLY THIS MORNING BUT GIVEN ONGOING SNOW,
BLOWING SNOW AND CURRENT CONDITIONS HAVE DECIDED NOT TO BEGIN
TRIMMING THE BLIZZARD WARNING YET.
BY MID DAY ISENTROPIC DOWN GLIDE WILL BEGIN TO DEVELOP WEST OF
OUR UPPER LOW WHICH WILL BE LOCATED NEAR SOUTH CENTRAL KANSAS. A
SURFACE HIGH WILL THEN BEGIN TO BUILD INTO WESTERN KANSAS FROM THE
NORTHWEST. MODEL SOUNDINGS CONTINUE TO SUGGEST TO CLOUD COVER
THROUGH MUCH OF THE DAY SO BASED ON THIS AND COLD AIR ADVECTION
OCCURRING OVER THE SNOW PACK WILL UNDERCUT GUIDANCE FOR HIGHS
TODAY.
TONIGHT SKIES WILL CLEAR AS WINDS DECREASE TO LESS THAN 10KTS.
WINDS NOT IDEAL FOR A GREAT NIGHT OF RADIATION COOLING BUT
CONDITIONS STILL FAVOR UNDERCUTTING CURRENT GUIDANCE AND STAYING
CLOSE TO THE CURRENT FORECAST OF WITH LOWS EARLY WEDNESDAY MORNING
IN THE SINGLE DIGITS.
WEDNESDAY SHOULD BE SUNNY AS WESTERLY DOWNSLOPE FLOW IMPROVES
ACROSS WESTERN KANSAS. DECENT WARMING OCCURS ABOVE THE SURFACE BUT
BASED ON SNOWFALL EXPECTED ACROSS SOUTHWEST KANSAS FEEL MUCH OF
THE WARMING WILL GO INTO SNOW MELT. AS A RESULT WILL UNDERCUT
GUIDANCE ONCE AGAIN AND FAVOR THE PREVIOUS FORECAST WHICH IS CLOSE
TO 10F COOLER THAN THE COOLEST GUIDANCE.
DAYS 3-7...
.LONG TERM /THURSDAY THROUGH MONDAY/
A PROGRESSIVE LONGWAVE PATTERN IS IN STORE FOR THE EXTENDED PERIOD,
WITH AT LEAST A COUPLE OF ADDITIONAL COLD FRONTAL PASSAGES ACROSS
THE CENTRAL HIGH PLAINS.
AFTER THE MAJOR SYSTEM THAT IS CAUSING THE BLIZZARD RIGHT NOW OVER
WESTERN KANSAS LIFTS EASTWARD INTO THE UPPER MIDWEST ON TUESDAY
NIGHT AND WEDNESDAY, ANOTHER PAIR OF SHARP MID LEVEL IMPULSES WILL
BE ROTATING THROUGH THE MEAN TROUGH. THE FIRST WILL ROTATE SOUTHWARD
FROM THE NORTHERN ROCKIES AND THE SECOND, JUST AHEAD OF THE NORTHERN
STREAM SHORTWAVE, FROM THE DESERT SOUTHWEST. FROM A LOOK AT THE GFS
AND ECMWF THE TWO WAVES APPEAR TO ENHANCE THE MID LEVEL BAROCLINICITY
ACROSS WESTERN KANSAS ON THURSDAY, WHILE A SURFACE COLD FRONT DIVES
SOUTHWARD ACROSS THE AREA EARLY IN THE DAY. BOTH MODELS HAVE BEEN
CONSISTENT IN PRODUCING BETWEEN 0.05" AND 0.15" OF PRECIPITATION
TIED TO THE LEADING SHORTWAVE, WITH POST SURFACE FRONT QPF. QUITE COLD
850 MB AIR ABOUT -5 T0 -8 SHOULD ENSURE THE PRECIPITATION TYPE WOULD
BE SNOW, AND AS A RESULT, IT IS POSSIBLE CENTRAL KANSAS AND MUCH OF
SOUTHWEST WILL BE EXPERIENCING ADDITIONAL, BUT PROBABLY MINOR
ACCUMULATIONS ON THURSDAY AFTERNOON. THE REMAINDER OF THE FORECAST
DOES LOOK DRY, BUT COLD. THE SECOND OF THESE UPPER SHORTWAVES
ROTATES THROUGH THE MEAN TROUGH ON FRIDAY AND SURFACE WINDS BEGIN TO
WEAKEN AS THE UPPER LEVEL HEIGHT FIELDS BECOME PARALLEL TO THE
MOUNTAIN BARRIER. FRIDAY WILL REMAIN COLD WITH VERY WEAK SURFACE
WINDS OVER THE AREA, BUT THE 850 MB TEMPERATURES BEGIN TO INCREASE
WITH STRONGER DOWNSLOPE FLOW OVER THE SNOWPACK. MODELS SEEM TO BUMP
MAXIMUM TEMPERATURES ABOUT 5 DEGREES ON SATURDAY AFTERNOON, BUT THIS
IS STILL WELL BELOW NORMAL. THE MODELS CONTINUE THOUGH THE END OF
THE WEEKEND DRY AND COOL WITH DEEP NORTHWEST FLOW OVER THE HIGH
PLAINS REGION INTO MONDAY.
&&
.AVIATION...
FOR THE 06Z TAF ISSUANCE... BLIZZARD OR NEAR BLIZZARD CONDITIONS
WILL CONTINUE THROUGH EARLY TUESDAY MORNING WITH THE DOMINANT
FLIGHT CATEGORY BEING VLIFR AT GCK AND DDC THROUGH MUCH OF THE
NIGHT TOWARD DAYBREAK. WIND SPEEDS WILL GRADUALLY DECREASE BY
DAYBREAK WITH VISIBILITIES IMPROVING AS WELL. AFTER THE SNOW
CEASES...LOW OVERCAST WILL LIKELY PERSIST THROUGH AT LEAST THE
EARLY AFTERNOON BEFORE CLEARING TAKES PLACE AND VFR CONDITIONS
RESUME. -UMSCHEID
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 27 9 30 14 / 90 0 0 10
GCK 28 6 29 13 / 90 0 0 10
EHA 27 5 29 13 / 50 0 0 10
LBL 27 6 30 15 / 50 0 0 10
HYS 29 6 30 15 / 100 0 0 20
P28 31 14 38 23 / 70 10 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
BLIZZARD WARNING UNTIL NOON CST /11 AM MST/ TODAY FOR KSZ030-031-
043>046-061>066-074>080-084>088.
WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR KSZ081-089-090.
&&
$$
FN18/33/25
AREA FORECAST DISCUSSION...UPDATED
NWS TOPEKA KS
1141 PM CST MON DEC 19 2011
...UPDATE TO AVIATION...
.DISCUSSION...
THE FOCUS OF THIS FORECAST REMAINS ON THE POTENT STORM SYSTEM WHICH
WILL MOVE OFF THE HIGH PLAINS AND BRING RAIN AND SNOW TO ALL OF
NORTHEAST AND EAST CENTRAL KANSAS TONIGHT AND TOMORROW.
20Z WATER VAPOR IMAGERY AND ASSOCIATED RUC ANALYSIS SHOWING THE 500
MB TROUGH MAKING A NORTHEAST TURN AS IT TAKES ON A NEGATIVE TILT
OVER FAR WESTERN TEXAS. STRONG ISENTROPIC LIFT CAUSING A WIDE SHIELD
OF PRECIPITATION MAINLY IN THE FORM OF RAIN TO MOVE NORTHWARD ACROSS
THE AREA. SOME ELEVATED INSTABILITY HAS ALLOWED FOR SOME WEAK
CONVECTION WITHIN THE AREA OF PRECIP ALLOWING FOR A FEW RUMBLES OF
THUNDER. WITH WARM LOW LEVEL TEMPERATURES ACROSS FAR EASTERN KANSAS
THE PRECIPITATION HAS FALLEN AS RAIN THROUGHOUT THE DAY. FURTHER TO
THE WEST COOLER AIR IN THE LOWER TO MID LEVELS HAS FACILITATED A
GRADUAL CHANGE OVER TO A MIX OF RAIN AND SNOW WITH SOME SLEET.
ACROSS CENTRAL AND SOUTHWEST KANSAS WHERE THE COLD AIR IS EVEN
DEEPER PRECIP HAS CHANGED COMPLETELY OVER TO SNOW. THE AREA WITH THE
BIGGEST CONCERN FOR THIS SYSTEM WILL BE ACROSS CENTRAL AND NORTH
CENTRAL KANSAS WHERE SNOW AMOUNTS COULD BE THE HIGHEST. BEST
FRONTOGENETICAL LIFT AND ASSOCIATED HIGHEST OMEGA LOOKS TO PERSIST
ACROSS THE AREA BETWEEN 00Z AND 12Z TONIGHT...AND THIS WILL LIKELY
BRING THE HEAVIEST SNOW...ESPECIALLY TO AREAS OF CENTRAL KANSAS.
GOOD LIFT THROUGH THE -8 TO -14 C DENDRITIC GROWTH LAYER WILL LIKELY
KEEP ALL PRECIP WEST AND NORTH OF A HIAWATHA TO COUNCIL GROVE LINE.
SNOW COULD RAPIDLY INCREASE WITH SNOW RATES APPROACHING 3 TO 5
INCHES OVER A 6 TO 10 HOUR PERIOD ACROSS THAT AREA. COMPLICATING THE
CONDITIONS WILL BE STRONG WINDS ACROSS CENTRAL KANSAS
OVERNIGHT...LEADING TO REDUCED VISIBILITIES AND DANGEROUS TRAVEL
CONDITIONS...ESPECIALLY ALONG INTERSTATE 70. VERY TRICKY PRECIP TYPE
FORECAST FOR AREAS ALONG AND EAST OF THE KANSAS TURNPIKE. FORECAST
SOUNDINGS INDICATE ICE CRYSTALS INTRODUCED INTO THE ATMOSPHERIC
COLUMN...BUT WARMER 850 MB TEMPS COULD TEMPER THE ABILITY OF SNOW TO
REACH THE SURFACE. HOWEVER WITH REAL TIME TEMPS RUNNING A BIT COOLER
THAN MODEL TEMPS...MAY NEED TO CALIBRATE MODELS WITH REAL TIME INFO
AND LEAN TOWARD A SLIGHTLY COOLER SOLUTION...FOR PRECIP TYPES AND
SNOW AMOUNTS ACROSS THE EASTERN COUNTIES. SHOULD PRECIP BE ABLE TO
CHANGE OVER TO SNOW BY 01 TO 03Z EAST OF THE AFOREMENTIONED HIAWATHA
TO COUNCIL GROVE LINE...MAY NEED TO BUMP UP SNOW
AMOUNTS...ESPECIALLY FOR THE TOPEKA AREA. AROUND 12Z TUESDAY MORNING
DRY MID LEVEL AIR WILL PUSH INTO THE AREA WHICH WILL REMOVE ICE
CRYSTALS FROM THE COLUMN FOR A FEW HOURS TUESDAY MORNING. DURING
THIS TIME EXPECT PRECIP TO GO FROM A LIGHT SNOW TO A LIGHT DRIZZLE
OR FREEZING DRIZZLE ACROSS AREAS WHERE TEMPS ARE BELOW FREEZING. BY
LATE TUESDAY AFTERNOON THE MID LEVEL TROWAL WILL SET UP NEAR THE
INTERSTATE 70 CORRIDOR WHICH COULD BRING ANOTHER ROUND OF LIGHT SNOW
FOR TUESDAY AFTERNOON AS THE ATMOSPHERIC COLUMN SHOULD BE COOL
ENOUGH ACROSS THE ENTIRE FORECAST AREA.
WILL NOT MAKE ANY MAJOR CHANGES TO THE ONGOING WARNING/ADVISORY
LOCATIONS AS COUNTIES CURRENTLY UNDER THE WINTER STORM WARNING ARE
STILL ON TRACK TO ACCUMULATE 6 TO 8 INCHES OF SNOW. THE COUNTIES
FURTHEST NORTH AND EAST CONTAIN LESSER CONFIDENCE IN REACHING THE 6
TO 8 INCH RANGE...BUT COUNTIES ALONG INTERSTATE 70 AND WEST OF THE
KANSAS TURNPIKE SHOULD EXPECT AT LEAST 4 TO 6 INCHES OF SNOW...WITH
HIGHER AMOUNTS ACROSS CENTRAL KANSAS. ALSO STRONG WINDS ALONG
INTERSTATE 70 WILL COMPLICATE TRAVEL CONDITIONS AS THEY WILL
COINCIDE WITH THE HEAVY SNOW OVERNIGHT TO BRING LOWERED VISIBILITY
AND DANGEROUS TRAVEL CONDITIONS.
EXPECT LIGHT SNOW TO GRADUALLY COME TO AN END BY EARLY WEDNESDAY
MORNING AS THE UPPER TROUGH EXITS COMPLETELY OUT OF THE AREA WITH
CLEARING SKIES AND SEASONABLE TEMPS.
ANOTHER SYSTEM SWINGS INTO THE PLAINS THURSDAY INTO FRIDAY BUT
WITH A NORTHERLY TRAJECTORY AND MORE LIMITED MOISTURE WILL CARRY
CHANCE TO SLIGHT CHANCE POPS AT THIS TIME. CONDITIONS CLEAR OUT
FOR SATURDAY WITH ANOTHER PUSH OF COLDER AIR SATURDAY NIGHT INTO
SUNDAY.
&&
.AVIATION...
UPPER LOW NOW MOVING EAST NORTHEASTWARD FROM THE TX PANHANDLE WILL
PASS OFF TO THE EAST OF THE TAF SITES AFT 00Z/20. UNTIL THEN...EXPECT
MVFR/IFR SNOW AND SOME SLEET MIX AND GUSTY WINDS FROM 07Z-11Z
BEFORE DRY SLOT OVER NORTHERN OK MOVES THROUGH ALLOWING FOR THE
DEVELOPMENT OF A SNOW/FREEZING DRIZZLE MIX IN IFR CIGS/VSBYS AFT
11Z THEN ENDING NEAR 23Z AS THE UPPER LOW MOVES TO THE EAST WITH
LINGERING MVFR STRATUS AND DECREASING WINDS THROUGH 06Z.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 PM CST TUESDAY FOR KSZ009>011-
020>023-034>036.
WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR KSZ008-012-
024-026-037>039.
WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR KSZ040-054-
055.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1140 PM CST MON DEC 19 2011
.AVIATION...
FOR THE 06Z TAF ISSUANCE...
BLIZZARD OR NEAR BLIZZARD CONDITIONS WILL CONTINUE THROUGH EARLY
TUESDAY MORNING WITH THE DOMINANT FLIGHT CATEGORY BEING VLIFR AT
GCK AND DDC THROUGH MUCH OF THE NIGHT TOWARD DAYBREAK. WIND
SPEEDS WILL GRADUALLY DECREASE BY DAYBREAK WITH VISIBILITIES
IMPROVING AS WELL. AFTER THE SNOW CEASES...LOW OVERCAST WILL
LIKELY PERSIST THROUGH AT LEAST THE EARLY AFTERNOON BEFORE
CLEARING TAKES PLACE AND VFR CONDITIONS RESUME. -UMSCHEID
&&
.PREV DISCUSSION... /ISSUED 506 PM CST MON DEC 19 2011/
AVIATION...
FOR THE 00Z TAF ISSUANCE...CIGS WILL REMAIN LIFR/IFR IN ASSOCIATION
WITH SN/BLSN. CIGS WILL EVENTUALLY IMPROVE TO MVFR TOWARDS 18Z TOMORROW.
WINDS WILL REMAIN STRONG AROUND 30 KT TONIGHT AND THEN ABATE IN THE
20-25 KT BY MORNING. -SUGDEN
PREV DISCUSSION... /ISSUED 320 PM CST MON DEC 19 2011/
SYNOPSIS...
THE OVERALL SYNOPSIS FROM THE 12Z...250MB CHART SHOWED A 80-KNOT
JET STREAK OF WIND FROM SOUTHWEST TEXAS THROUGH SOUTHWEST KANSAS
TO SOUTHERN IOWA. A STRONGER 110KT NORTHWEST JET WAS ENTERING BAJA
CALIFORNIA (W. MEXICO), WHILE A 120-KNOT JET STRETCHED FROM
NORTHERN MINNESOTA TO SOUTHWEST QUEBEC. THE 500MB CHART AT 12Z HAD
A LARGE UPPER LOW PRESSURE SYSTEM OVER EXTREME WESTERN TEXAS, WITH
MOISTURE FLOWING NORTHEASTWARD INTO KANSAS. THE 500MB TEMPERATURE
AT DDC WAS AT 17C. THE 700 MB CHART LOOKED SIMILAR TO THE 500MB
CHART PATTERN, BUT WITH THE H7 LOW PRESSURE OVER SOUTH CENTRAL NEW
MEXICO. A COLD FRONT WAS EVIDENT AT 12Z AT THE 850MB LEVEL ACROSS
NORTH CENTRAL KANSAS, WITH LBF AT -04C AND DDC AT +10C.
DISCUSSION...
DAYS 1-2...
THE UPPER STORM SYSTEM MOVING ACROSS NEW MEXICO AND TEXAS, AND
INTO NORTHERN OKLAHOMA, WAS BRINGING WINTER-LIKE WEATHER TO MOST
OF SOUTHWESTERN KANSAS THIS AFTERNOON. THERE WAS A BAND OF RAIN,
SOME MODERATE, THAT MOVED NORTH FROM FROM OKLAHOMA MORNING LAID
DOWN 0.02 TO 0.50 INCH OF RAIN ACROSS MUCH OF OUR SOUTHERN CWA.
THIS SOAKED UPPER LAYER OF SURFACE GROUND WILL DELAY TO ONSET OF
ACCUMULATING SNOW, BUT SNOW RATES OF .5 TO 1.0-INCH PER HOUR AT
TIMES WILL LEAD TO A QUICK ACCUMULATION. FURTHERMORE, PER THE
FORECAST SOUNDINGS FROM THE NAM AND RUC MODELS BOTH SHOWED A WARM
ELEVATED LAYER OF +2 DEGREES, INDICATING THERE MAY BE SOME SLEET
OR LIGHT FREEZING RAIN BEFORE THE EASTERN PART OF THE CWA CHANGES
TO ALL SNOW, SO WILL MENTION THAT. A SURFACE COLD FRONT WAS
WORKING SOUTH THROUGH THE CWA TODAY, AND CLEARED THE SOUTHEAST
PART OF OUR FORECAST AREA BETWEEN 20 AND 21Z. WHERE THE
OVERRIDING COLD AIR WILL MEET THE BEST LIFT OVER THE ELEVATED
FRONT IS WHERE A HEAVY BAND OF SNOW SHOULD SET UP...FROM
APPROXIMATELY LAKIN TO GARDEN CITY TO NESS CITY...WHERE 10 TO 11
INCHES OF SNOW IS POSSIBLE BY TUESDAY AFTERNOON. SOUTHEAST OF THAT
ZONE, IN THE LIBERAL TO DODGE CITY TO KINSLEY TO SAINT JOHN ZONE...I
STILL THINK THERE COULD BE SOME BANDS OF HEAVY SNOW TONIGHT...WITH
LESS DURATION THAN NORTH OF THERE, AND 5 TO 8 INCHES OF SNOW IS
EXPECTED THERE BY TUESDAY AFTERNOON. IN BOTH THESE ZONES...STRONG
NORTH WINDS OF 20 TO 35 MPH WITH GUSTS TO NEAR 45 MPH WILL COMBINE
WITH THE SNOW TO CREATE LOW VISIBILITIES IN BLOWING AND DRIFTING
SNOW. WITH A FEW AREAS IN OUR EXTREME WEST SUCH AS TRB AND 3K3
ALREADY REPORTING M1/4SM +SN...THINK THIS COLD AIR AND STRONG
WINDS WILL WRAP TO THE EAST TONIGHT. THEREFORE, THE BLIZZARD
WARNING WILL CONTINUE THROUGH NOON TUESDAY, NORTHWEST OF A LINE
FROM COLDWATER TO PRATT. A WINTER WEATHER ADVISORY FOR 3 TO 5
INCHES OF SNOW AND BLOWING SNOW WILL ALSO CONTINUE THROUGH NOON
TUESDAY FOR PRATT, BARBER AND COMANCHE COUNTIES.
AS FOR TEMPS, THINK OVERNIGHT THAT LOWER DEW POINTS WILL BE
FILTERING IN FROM THE NORTH ON THE STRONG FLOW. STAYED PRETTY
CLOSE TO THE PREVIOUS FORECAST OF MIN T`S FROM AROUND 17F IN EHA
TO 23F IN P28. TOMORROW WILL SEE THICK CLOUDS AROUND ALONG WITH
EARLY SNOW. THE TEMPERATURE WILL NOT RISE MUCH AND SHOULD TOP OUT
IN THE 27F TO 30F DEGREE RANGE. CLOUDS WILL CLEAR OUT FROM WEST TO
EAST TUESDAY EVENING, AND WITH FRESH SNOW COVER EXPECTED AND LIGHT
WEST WINDS, THE TEMPERATURE SHOULD PLUMMET. LOWS TUESDAY NIGHT
WILL BE QUITE COLD, RANGING FROM A VERY COLD 5F IN EHA TO 14F IN
P28. WEDNESDAY, WE WILL STILL BE IN THE GRIP OF COLD ARCTIC AIR
CENTERED TO OUR NORTHEAST, BUT NOT MUCH WARMER THAN TUESDAY IN
MOST SPOTS. HAVE WENT WITH A MAX T FORECAST FOR WEDNESDAY IN THE
27F DEGREE RANGE NEAR LBL, EHA, GCK AND DDC, RANGING UP TO 33F AT P28.
DAYS 3-7...
A NORTHERN BRANCH SHORTWAVE TROUGH WILL DIG TO NEAR THE FOUR CORNERS
ON THURSDAY WITH SOME LIGHT SNOW EXPECTED MOSTLY IN THE AFTERNOON
ACROSS WESTERN KANSAS. THE TROUGH THEN WILL MOVE INTO THE PLAINS ON
FRIDAY WITH LIGHT SNOW ENDING FROM WEST TO EAST ON FRIDAY MORNING.
EXPECT LESS THAN AN INCH ACCUMULATION. ANOTHER LONGER WAVE TROUGH
WILL MOVE ACROSS THE CENTRAL CONUS ON SUNDAY WITH MAINLY DRY
CONDITIONS AND LESS MOISTURE TO WORK WITH. THE GFS AND NEW ECMWF ARE
DIFFERENT WITH ONE SHOWING A SHORTWAVE RIDGE AND THE OTHER A
SHORTWAVE TROUGH BUT LOOKS TO DRY FOR ANY PRECIPITATION.
A COLD FRONT WILL MOVE INTO THE CENTRAL PLAINS WITH HIGH PRESSURE
AND LOWS IN THE TEENS TO LOW 20S ON THURSDAY MORNING AND HIGHS FROM
THE UPPER 20S NORTH TO AROUND 34 SOUTHEAST FA ON THURSDAY. A RIDGE
OF COLD HIGH PRESSURE MOVES INTO THE PLAINS ON FRIDAY WITH LOWS IN
THE TEENS AND HIGHS ONLY IN THE MID 20S. SATURDAY MORNING LOOKS THE
COLDEST WITH LIGHT WINDS AND LOWS IN THE SINGLE DIGITS. FOR SATURDAY
HIGHS SHOULD BE AROUND 30 TO 35. ON CHRISTMAS DAY SUNDAY MORNING
LOWS WILL BE MAINLY IN THE TEENS AND HIGHS AROUND 30 TO 35 WITH
MOSTLY CLEAR SKIES. ON MONDAY MORNING LOWS WILL BE COLD AGAIN WITH
CLEAR SKIES AROUND 10 TO 15 DEGREES AND HIGHS MONDAY WITH WARMING
SOUTHWEST WINDS AND HIGHS FROM THE MID 30S TO LOWER 40S.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 20 27 9 27 / 100 80 0 0
GCK 19 28 6 27 / 100 70 0 0
EHA 17 28 5 27 / 100 60 0 0
LBL 20 28 6 27 / 100 60 0 0
HYS 23 29 6 28 / 100 100 0 0
P28 26 30 14 36 / 100 90 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
BLIZZARD WARNING UNTIL NOON CST /11 AM MST/ TUESDAY FOR KSZ030-
031-043>046-061>066-074>080-084>088.
WINTER WEATHER ADVISORY UNTIL NOON CST TUESDAY FOR KSZ081-089-
090.
&&
$$
FN99/99/25
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
110 PM EST TUE DEC 20 2011
.SYNOPSIS...
A COLD FRONT STALLING ACROSS THE UPPER OHIO VALLEY WILL PROVIDE
RAIN TODAY. LOW PRESSURE, COMING NORTHEAST FROM TEXAS, WILL BRING
MILDER TEMPERATURES AND RAIN TONIGHT INTO WEDNESDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
PER RECENT RADAR AND SURFACE DATA, COUPLED WITH RECENT HRRR AND
NAM MODEL OUTPUT, EXPECT PRECIPITATION TO CONTINUE THIS AFTERNOON
AND BEGIN TO DECREASE IN COVERAGE INTO THE EARLY EVENING. NAM
MODEL OUTPUT SHOWS SOUTHEASTERLY WINDS INCREASE AHEAD OF THE LOW
PRESSURE CENTER INCOMING FROM TEXAS, CAUSING A SLOW WARM UP INTO
TONIGHT.
MODELS SHOW THERE MAY BE A BREAK IN THE RAIN SHOWERS EARLY TONIGHT, THEN
AN INCREASE IN RAIN SHOWER COVERAGE LATE TONIGHT AND DAYTIME
WEDNESDAY AS THE LOW PRESSURE CENTER PASSES NORTHEASTWARD THROUGH
OHIO.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
BLEND OF RECENT MODELS SHOWS SCATTERED POST-SYSTEM SHOWERS
CONTINUING IN THE WAKE OF THE EXITING LOW PRESSURE WEDNESDAY NIGHT.
A SECOND LOW PRESSURE SYSTEM, COMING NORTHEAST FROM LOUISIANA,
WILL PROVIDE SHOWERS THURSDAY NIGHT AND FRIDAY.
SOUTHWEST WINDS ALOFT WILL ENSURE TEMPERATURES REMAINING MILDER
THAN NORMAL, AS INDICATED BY RECENT GFS AND NAM MOS. THIS MILDNESS
WILL PREVENT ANY CHANGE TO WINTRY TYPE PRECIPITATION THIS PERIOD.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS IN FAIRLY GOOD AGREEMENT WITH SERIES OF SHORT WAVES RUNNING
ALONG THE NORTHERN PERIPHERY OF SUBTROPICAL RIDGE SATURDAY.
PROBLEM IS HOW MUCH PHASING WILL OCCUR...AND HOW FAR NORTH
PRECIPITATION WILL COME AS SURFACE LOWS MOVE ALONG THE FRONT IN
THE MID ATLANTIC STATES.
DID NOT STRAY TOO FAR FROM HPC GRIDS WITH BEST CHANCES OF PRECIP
SATURDAY INTO SUNDAY CHRISTMAS DAY. THERE CAN BE SUFFICIENT COOL
DOWN TO PROVIDE A CHANCE OF MIXED RAIN AND SNOW SHOWERS SOUTH
WITH SNOW SHOWERS IN THE NORTH.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
IFR CEILINGS WITH MVFR VISIBILITIES WILL MOSTLY PREVAIL ACROSS THE
TERMINALS INTO THE EVENING AS A FRONTAL BOUNDARY SLOWLY LIFTS NORTHWARD
ACROSS THE AREA. THE EXCEPTION WILL BE KMGW, WHERE VFR CONDITIONS
WILL PREVAIL UNTIL AFTER 03Z. SHOWERS WILL MOSTLY PUSH EAST OF THE
AREA THIS EVENING, WITH SHOWERS DIMINISHING IN COVERAGE.
ABUNDANT LOW-LEVEL MOISTURE WILL ALLOW FOR IFR CEILINGS TO LOWER
TO LIFR OVERNIGHT AND FOR MVFR VISIBILITIES TO CONTINUE TO PREVAIL.
A FEW LINGERING SHOWERS CANNOT BE RULED OUT OVERNIGHT, ALTHOUGH DO
NOT EXPECT THE MORE PERSISTENT RAINFALL TO RETURN UNTIL CLOSER TO
DAWN ON WEDNESDAY.
A SURFACE LOW WILL PUSH INTO THE OHIO VALLEY ON WEDNESDAY AND ALLOW
FOR SHOWERS WITH IFR CEILINGS TO PREVAIL MUCH OF THE DAY. THERE
IS A CHANCE OF THUNDERSTORMS IN THE AFTERNOON ON WEDNESDAY AS WARM
AIR IS DRAWN INTO THE AREA AHEAD OF THE LOW.
OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...
THE SURFACE LOW WILL PULL NORTHEAST OF THE AREA ON WEDNESDAY NIGHT
WITH SHOWERS ENDING. MVFR CEILINGS WILL CONTINUE TO PREVAIL
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.
THE NEXT SURFACE LOW WILL MOVE FROM THE SOUTHEAST INTO THE MID-
ATLANTIC THURSDAY NIGHT INTO FRIDAY, BRINGING SHOWERS WITH
RESTRICTIONS TO THE TERMINALS SOUTHEAST OF KPIT. VFR CONDITIONS
WILL MOSTLY PREVAIL FRIDAY INTO SATURDAY. LOW CONFIDENCE FORECAST
FOR SUNDAY, WITH A CHANCE OF RAIN AND SNOW SHOWERS WITH
RESTRICTIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1221 PM EST TUE DEC 20 2011
.SYNOPSIS...
A COLD FRONT STALLING ACROSS THE UPPER OHIO VALLEY WILL PROVIDE
RAIN TODAY. HOWEVER, THERE CAN BE A SHORT PERIOD OF WET SNOW THIS
MORNING NORTH OF PITTSBURGH. LOW PRESSURE, COMING NORTHEAST FROM TEXAS,
WILL BRING MILDER TEMPERATURES AND RAIN TONIGHT AND WEDNESDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
UPDATED TO REMOVE MORNING WORDING.
PER RECENT RADAR AND SURFACE DATA, COUPLED WITH RECENT HRRR AND
NAM MODEL OUTPUT, EXPECT PRECIPITATION ACROSS THE ENTIRE UPPER
OHIO VALLEY INTO MIDDAY. RECENT SURFACE DATA SHOWS LOW
VISIBILITIES ACROSS HIGHER TERRAIN WHICH CAN AFFECT TRAVEL ON
I-68 AND PA TURNPIKE.
THE COLD FRONT MOVING SLOWLY SOUTH FROM THE I-80 CORRIDOR MAY
LOWER SURFACE TEMPERATURES ENOUGH TO CAUSE A CHANGE TO WET SNOW
FOR A TIME THIS MORNING AS FAR SOUTH AS COLUMBIANA COUNTY OHIO,
BEAVER COUNTY, NORTHERN ALLEGHENY COUNTY AND NORTHERN INDIANA
COUNTY PENNSYLVANIA...ALSO ACROSS THE HIGHER MOUNTAIN RIDGES
FARTHER SOUTH. RAIN-WETTED GROUND SHOULD RESULT IN MINIMAL SNOW
ACCUMULATION, IF ANY.
WILL ISSUE STATEMENT REGARDING THE POSSIBILITY OF ICY CONDITIONS
WHERE TEMPERATURES REACH THE FREEZING POINT NEAR THE I-80
CORRIDOR. WILL ALSO ISSUE A STATEMENT MENTIONING LOW VISIBILITIES
IN FOG FOR HIGHER TERRAIN SOUTH.
EXPECT TEMPERATURES TO BEGIN SLOWLY WARMING LATER THIS MORNING, AS POSTFRONTAL
NORTH WINDS ABATE BEHIND THE STALLING COLD FRONT. THIS WILL
LIKEWISE ALLOW DAYTIME PROCESSES TO RAISE TEMPERATURES ALSO. HENCE
LOCATIONS WITH WET SNOW EARLY THIS MORNING SHOULD SEE IT END BY
MIDDAY. NAM MODEL OUTPUT SHOWS SOUTHEASTERLY WINDS INCREASE AHEAD
OF THE LOW PRESSURE CENTER INCOMING FROM TEXAS, CAUSING A SLOW
WARM UP INTO TONIGHT.
MODELS SHOW THERE MAY BE A BREAK IN THE RAIN SHOWERS EARLY TONIGHT, THEN
AN INCREASE IN RAIN SHOWER COVERAGE LATE TONIGHT AND DAYTIME
WEDNESDAY AS THE LOW PRESSURE CENTER PASSES NORTHEASTWARD THROUGH
OHIO.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
BLEND OF RECENT MODELS SHOWS SCATTERED POST-SYSTEM SHOWERS
CONTINUING IN THE WAKE OF THE EXITING LOW PRESSURE WEDNESDAY NIGHT.
A SECOND LOW PRESSURE SYSTEM, COMING NORTHEAST FROM LOUISIANA,
WILL PROVIDE SHOWERS THURSDAY NIGHT AND FRIDAY.
SOUTHWEST WINDS ALOFT WILL ENSURE TEMPERATURES REMAINING MILDER
THAN NORMAL, AS INDICATED BY RECENT GFS AND NAM MOS. THIS MILDNESS
WILL PREVENT ANY CHANGE TO WINTRY TYPE PRECIPITATION THIS PERIOD.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS IN FAIRLY GOOD AGREEMENT WITH SERIES OF SHORT WAVES RUNNING
ALONG THE NORTHERN PERIPHERY OF SUBTROPICAL RIDGE SATURDAY.
PROBLEM IS HOW MUCH PHASING WILL OCCUR...AND HOW FAR NORTH
PRECIPITATION WILL COME AS SURFACE LOWS MOVE ALONG THE FRONT IN
THE MID ATLANTIC STATES.
DID NOT STRAY TOO FAR FROM HPC GRIDS WITH BEST CHANCES OF PRECIP
SATURDAY INTO SUNDAY CHRISTMAS DAY. THERE CAN BE SUFFICIENT COOL
DOWN TO PROVIDE A CHANCE OF MIXED RAIN AND SNOW SHOWERS SOUTH
WITH SNOW SHOWERS IN THE NORTH.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
PER RECENT SURFACE AND RADAR DATA, ALONG WITH HRRR MODEL OUTPUT,
FOR TAF SITES SOUTH OF KFKL AND KDUJ, EXPECT MVFR RAIN AND FOG WITH
SOME INTERLUDES OF IFR THROUGH 16Z. FOR KFKL AND KDUJ, THERE CAN
BE A PERIOD OF IFR SNOW AND FOG THROUGH 16Z.
WITH THE FRONT THEN RETREATING NORTHWARD THIS AFTERNOON, EXPECT
THE RAIN TO DECREASE IN COVERAGE INTO EARLY TONIGHT WITH FLIGHT
CONDITIONS MAINLY MVFR ALL LOCATIONS.
LOW PRESSURE CENTER MOVING NORTHEASTWARD FROM TEXAS TODAY THROUGH
OHIO WEDNESDAY, WILL PROVIDE FREQUENT RAIN SHOWERS LATE TONIGHT
AND DAYTIME WEDNESDAY. THIS WILL LIKELY CAUSE ADDITIONAL BOUTS OF
IFR RESTRICTIONS.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
MVFR WEDNESDAY NIGHT IN LINGERING POST SYSTEM SHOWERS AND CLOUDS
CAN GIVE WAY TO VFR THURSDAY. THE POTENTIAL FOR RESTRICTIONS
THEN RETURNS WITH MIXED PRECIPITATION FRIDAY AND SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1044 AM EST TUE DEC 20 2011
.SYNOPSIS...
A COLD FRONT STALLING ACROSS THE UPPER OHIO VALLEY WILL PROVIDE
RAIN TODAY. HOWEVER, THERE CAN BE A SHORT PERIOD OF WET SNOW THIS
MORNING NORTH OF PITTSBURGH. LOW PRESSURE, COMING NORTHEAST FROM TEXAS,
WILL BRING MILDER TEMPERATURES AND RAIN TONIGHT AND WEDNESDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
UPDATED TO EXTEND PATCHY DENSE FOG IN THE MOUNTAINS FOR SEVERAL HOURS.
PER RECENT RADAR AND SURFACE DATA, COUPLED WITH RECENT HRRR AND
NAM MODEL OUTPUT, EXPECT PRECIPITATION ACROSS THE ENTIRE UPPER
OHIO VALLEY INTO MIDDAY. RECENT SURFACE DATA SHOWS LOW
VISIBILITIES ACROSS HIGHER TERRAIN WHICH CAN AFFECT TRAVEL ON
I-68 AND PA TURNPIKE.
THE COLD FRONT MOVING SLOWLY SOUTH FROM THE I-80 CORRIDOR MAY
LOWER SURFACE TEMPERATURES ENOUGH TO CAUSE A CHANGE TO WET SNOW
FOR A TIME THIS MORNING AS FAR SOUTH AS COLUMBIANA COUNTY OHIO,
BEAVER COUNTY, NORTHERN ALLEGHENY COUNTY AND NORTHERN INDIANA
COUNTY PENNSYLVANIA...ALSO ACROSS THE HIGHER MOUNTAIN RIDGES
FARTHER SOUTH. RAIN-WETTED GROUND SHOULD RESULT IN MINIMAL SNOW
ACCUMULATION, IF ANY.
WILL ISSUE STATEMENT REGARDING THE POSSIBILITY OF ICY CONDITIONS
WHERE TEMPERATURES REACH THE FREEZING POINT NEAR THE I-80
CORRIDOR. WILL ALSO ISSUE A STATEMENT MENTIONING LOW VISIBILITIES
IN FOG FOR HIGHER TERRAIN SOUTH.
EXPECT TEMPERATURES TO BEGIN SLOWLY WARMING LATER THIS MORNING, AS POSTFRONTAL
NORTH WINDS ABATE BEHIND THE STALLING COLD FRONT. THIS WILL
LIKEWISE ALLOW DAYTIME PROCESSES TO RAISE TEMPERATURES ALSO. HENCE
LOCATIONS WITH WET SNOW EARLY THIS MORNING SHOULD SEE IT END BY
MIDDAY. NAM MODEL OUTPUT SHOWS SOUTHEASTERLY WINDS INCREASE AHEAD
OF THE LOW PRESSURE CENTER INCOMING FROM TEXAS, CAUSING A SLOW
WARM UP INTO TONIGHT.
MODELS SHOW THERE MAY BE A BREAK IN THE RAIN SHOWERS EARLY TONIGHT, THEN
AN INCREASE IN RAIN SHOWER COVERAGE LATE TONIGHT AND DAYTIME
WEDNESDAY AS THE LOW PRESSURE CENTER PASSES NORTHEASTWARD THROUGH
OHIO.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
BLEND OF RECENT MODELS SHOWS SCATTERED POST-SYSTEM SHOWERS
CONTINUING IN THE WAKE OF THE EXITING LOW PRESSURE WEDNESDAY NIGHT.
A SECOND LOW PRESSURE SYSTEM, COMING NORTHEAST FROM LOUISIANA,
WILL PROVIDE SHOWERS THURSDAY NIGHT AND FRIDAY.
SOUTHWEST WINDS ALOFT WILL ENSURE TEMPERATURES REMAINING MILDER
THAN NORMAL, AS INDICATED BY RECENT GFS AND NAM MOS. THIS MILDNESS
WILL PREVENT ANY CHANGE TO WINTRY TYPE PRECIPITATION THIS PERIOD.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS IN FAIRLY GOOD AGREEMENT WITH SERIES OF SHORT WAVES RUNNING
ALONG THE NORTHERN PERIPHERY OF SUBTROPICAL RIDGE SATURDAY.
PROBLEM IS HOW MUCH PHASING WILL OCCUR...AND HOW FAR NORTH
PRECIPITATION WILL COME AS SURFACE LOWS MOVE ALONG THE FRONT IN
THE MID ATLANTIC STATES.
DID NOT STRAY TOO FAR FROM HPC GRIDS WITH BEST CHANCES OF PRECIP
SATURDAY INTO SUNDAY CHRISTMAS DAY. THERE CAN BE SUFFICIENT COOL
DOWN TO PROVIDE A CHANCE OF MIXED RAIN AND SNOW SHOWERS SOUTH
WITH SNOW SHOWERS IN THE NORTH.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
PER RECENT SURFACE AND RADAR DATA, ALONG WITH HRRR MODEL OUTPUT,
FOR TAF SITES SOUTH OF KFKL AND KDUJ, EXPECT MVFR RAIN AND FOG WITH
SOME INTERLUDES OF IFR THROUGH 16Z. FOR KFKL AND KDUJ, THERE CAN
BE A PERIOD OF IFR SNOW AND FOG THROUGH 16Z.
WITH THE FRONT THEN RETREATING NORTHWARD THIS AFTERNOON, EXPECT
THE RAIN TO DECREASE IN COVERAGE INTO EARLY TONIGHT WITH FLIGHT
CONDITIONS MAINLY MVFR ALL LOCATIONS.
LOW PRESSURE CENTER MOVING NORTHEASTWARD FROM TEXAS TODAY THROUGH
OHIO WEDNESDAY, WILL PROVIDE FREQUENT RAIN SHOWERS LATE TONIGHT
AND DAYTIME WEDNESDAY. THIS WILL LIKELY CAUSE ADDITIONAL BOUTS OF
IFR RESTRICTIONS.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
MVFR WEDNESDAY NIGHT IN LINGERING POST SYSTEM SHOWERS AND CLOUDS
CAN GIVE WAY TO VFR THURSDAY. THE POTENTIAL FOR RESTRICTIONS
THEN RETURNS WITH MIXED PRECIPITATION FRIDAY AND SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
811 AM EST TUE DEC 20 2011
.SYNOPSIS...
A COLD FRONT STALLING ACROSS THE UPPER OHIO VALLEY WILL PROVIDE
RAIN TODAY. HOWEVER, THERE CAN BE A SHORT PERIOD OF WET SNOW THIS
MORNING NORTH OF PITTSBURGH. LOW PRESSURE, COMING NORTHEAST FROM TEXAS,
WILL BRING MILDER TEMPERATURES AND RAIN TONIGHT AND WEDNESDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
UPDATED FOR MINOR ADJUSTMENTS TO WINDS THIS MORNING.
PER RECENT RADAR AND SURFACE DATA, COUPLED WITH RECENT HRRR AND
NAM MODEL OUTPUT, EXPECT PRECIPITATION ACROSS THE ENTIRE UPPER
OHIO VALLEY INTO MIDDAY. RECENT SURFACE DATA SHOWS LOW
VISIBILITIES ACROSS HIGHER TERRAIN WHICH CAN AFFECT TRAVEL ON
I-68 AND PA TURNPIKE.
THE COLD FRONT MOVING SLOWLY SOUTH FROM THE I-80 CORRIDOR MAY
LOWER SURFACE TEMPERATURES ENOUGH TO CAUSE A CHANGE TO WET SNOW
FOR A TIME THIS MORNING AS FAR SOUTH AS COLUMBIANA COUNTY OHIO,
BEAVER COUNTY, NORTHERN ALLEGHENY COUNTY AND NORTHERN INDIANA
COUNTY PENNSYLVANIA...ALSO ACROSS THE HIGHER MOUNTAIN RIDGES
FARTHER SOUTH. RAIN-WETTED GROUND SHOULD RESULT IN MINIMAL SNOW
ACCUMULATION, IF ANY.
WILL ISSUE STATEMENT REGARDING THE POSSIBILITY OF ICY CONDITIONS
WHERE TEMPERATURES REACH THE FREEZING POINT NEAR THE I-80
CORRIDOR. WILL ALSO ISSUE A STATEMENT MENTIONING LOW VISIBILITIES
IN FOG FOR HIGHER TERRAIN SOUTH.
EXPECT TEMPERATURES TO BEGIN SLOWLY WARMING LATER THIS MORNING, AS POSTFRONTAL
NORTH WINDS ABATE BEHIND THE STALLING COLD FRONT. THIS WILL
LIKEWISE ALLOW DAYTIME PROCESSES TO RAISE TEMPERATURES ALSO. HENCE
LOCATIONS WITH WET SNOW EARLY THIS MORNING SHOULD SEE IT END BY
MIDDAY. NAM MODEL OUTPUT SHOWS SOUTHEASTERLY WINDS INCREASE AHEAD
OF THE LOW PRESSURE CENTER INCOMING FROM TEXAS, CAUSING A SLOW
WARM UP INTO TONIGHT.
MODELS SHOW THERE MAY BE A BREAK IN THE RAIN SHOWERS EARLY TONIGHT, THEN
AN INCREASE IN RAIN SHOWER COVERAGE LATE TONIGHT AND DAYTIME
WEDNESDAY AS THE LOW PRESSURE CENTER PASSES NORTHEASTWARD THROUGH
OHIO.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
BLEND OF RECENT MODELS SHOWS SCATTERED POST-SYSTEM SHOWERS
CONTINUING IN THE WAKE OF THE EXITING LOW PRESSURE WEDNESDAY NIGHT.
A SECOND LOW PRESSURE SYSTEM, COMING NORTHEAST FROM LOUISIANA,
WILL PROVIDE SHOWERS THURSDAY NIGHT AND FRIDAY.
SOUTHWEST WINDS ALOFT WILL ENSURE TEMPERATURES REMAINING MILDER
THAN NORMAL, AS INDICATED BY RECENT GFS AND NAM MOS. THIS MILDNESS
WILL PREVENT ANY CHANGE TO WINTRY TYPE PRECIPITATION THIS PERIOD.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS IN FAIRLY GOOD AGREEMENT WITH SERIES OF SHORT WAVES RUNNING
ALONG THE NORTHERN PERIPHERY OF SUBTROPICAL RIDGE SATURDAY.
PROBLEM IS HOW MUCH PHASING WILL OCCUR...AND HOW FAR NORTH
PRECIPITATION WILL COME AS SURFACE LOWS MOVE ALONG THE FRONT IN
THE MID ATLANTIC STATES.
DID NOT STRAY TOO FAR FROM HPC GRIDS WITH BEST CHANCES OF PRECIP
SATURDAY INTO SUNDAY CHRISTMAS DAY. THERE CAN BE SUFFICIENT COOL
DOWN TO PROVIDE A CHANCE OF MIXED RAIN AND SNOW SHOWERS SOUTH
WITH SNOW SHOWERS IN THE NORTH.
&&
.AVIATION /13Z TUESDAY THROUGH SATURDAY/...
PER RECENT SURFACE AND RADAR DATA, ALONG WITH HRRR MODEL OUTPUT,
FOR TAF SITES SOUTH OF KFKL AND KDUJ, EXPECT MVFR RAIN AND FOG WITH
SOME INTERLUDES OF IFR THROUGH 16Z. FOR KFKL AND KDUJ, THERE CAN
BE A PERIOD OF IFR SNOW AND FOG THROUGH 16Z.
WITH THE FRONT THEN RETREATING NORTHWARD THIS AFTERNOON, EXPECT
THE RAIN TO DECREASE IN COVERAGE INTO EARLY TONIGHT WITH FLIGHT
CONDITIONS MAINLY MVFR ALL LOCATIONS.
LOW PRESSURE CENTER MOVING NORTHEASTWARD FROM TEXAS TODAY THROUGH
OHIO WEDNESDAY, WILL PROVIDE FREQUENT RAIN SHOWERS LATE TONIGHT
AND DAYTIME WEDNESDAY. THIS WILL LIKELY CAUSE ADDITIONAL BOUTS OF
IFR RESTRICTIONS.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
MVFR WEDNESDAY NIGHT IN LINGERING POST SYSTEM SHOWERS AND CLOUDS
CAN GIVE WAY TO VFR THURSDAY. THE POTENTIAL FOR RESTRICTIONS
THEN RETURNS WITH MIXED PRECIPITATION FRIDAY AND SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
537 AM EST TUE DEC 20 2011
.SYNOPSIS...
A COLD FRONT STALLING ACROSS THE UPPER OHIO VALLEY WILL PROVIDE
RAIN TODAY. HOWEVER, THERE CAN BE A SHORT PERIOD OF WET SNOW THIS
MORNING NORTH OF PITTSBURGH. LOW PRESSURE, COMING NORTHEAST FROM TEXAS,
WILL BRING MILDER TEMPERATURES AND RAIN TONIGHT AND WEDNESDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
UPDATED FORECAST TO ADD MENTION OF AREAS OF DENSE FOG ACROSS THE
WV-MD-SOUTHWEST PA MOUNTAINS INTO MID-MORNING.
PER RECENT RADAR AND SURFACE DATA, COUPLED WITH RECENT HRRR AND
NAM MODEL OUTPUT, EXPECT PRECIPITATION ACROSS THE ENTIRE UPPER
OHIO VALLEY INTO MIDDAY. RECENT SURFACE DATA SHOWS LOW
VISIBILITIES ACROSS HIGHER TERRAIN WHICH CAN AFFECT TRAVEL ON
I-68 AND PA TURNPIKE.
THE COLD FRONT MOVING SLOWLY SOUTH FROM THE I-80 CORRIDOR MAY
LOWER SURFACE TEMPERATURES ENOUGH TO CAUSE A CHANGE TO WET SNOW
FOR A TIME THIS MORNING AS FAR SOUTH AS COLUMBIANA COUNTY OHIO,
BEAVER COUNTY, NORTHERN ALLEGHENY COUNTY AND NORTHERN INDIANA
COUNTY PENNSYLVANIA...ALSO ACROSS THE HIGHER MOUNTAIN RIDGES
FARTHER SOUTH. RAIN-WETTED GROUND SHOULD RESULT IN MINIMAL SNOW
ACCUMULATION, IF ANY.
WILL ISSUE STATEMENT REGARDING THE POSSIBILITY OF ICY CONDITIONS
WHERE TEMPERATURES REACH THE FREEZING POINT NEAR THE I-80
CORRIDOR. WILL ALSO ISSUE A STATEMENT MENTIONING LOW VISIBILITIES
IN FOG FOR HIGHER TERRAIN SOUTH.
EXPECT TEMPERATURES TO BEGIN SLOWLY WARMING LATER THIS MORNING, AS POSTFRONTAL
NORTH WINDS ABATE BEHIND THE STALLING COLD FRONT. THIS WILL
LIKEWISE ALLOW DAYTIME PROCESSES TO RAISE TEMPERATURES ALSO. HENCE
LOCATIONS WITH WET SNOW EARLY THIS MORNING SHOULD SEE IT END BY
MIDDAY. NAM MODEL OUTPUT SHOWS SOUTHEASTERLY WINDS INCREASE AHEAD
OF THE LOW PRESSURE CENTER INCOMING FROM TEXAS, CAUSING A SLOW
WARM UP INTO TONIGHT.
MODELS SHOW THERE MAY BE A BREAK IN THE RAIN SHOWERS EARLY TONIGHT, THEN
AN INCREASE IN RAIN SHOWER COVERAGE LATE TONIGHT AND DAYTIME
WEDNESDAY AS THE LOW PRESSURE CENTER PASSES NORTHEASTWARD THROUGH
OHIO.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
BLEND OF RECENT MODELS SHOWS SCATTERED POST-SYSTEM SHOWERS
CONTINUING IN THE WAKE OF THE EXITING LOW PRESSURE WEDNESDAY NIGHT.
A SECOND LOW PRESSURE SYSTEM, COMING NORTHEAST FROM LOUISIANA,
WILL PROVIDE SHOWERS THURSDAY NIGHT AND FRIDAY.
SOUTHWEST WINDS ALOFT WILL ENSURE TEMPERATURES REMAINING MILDER
THAN NORMAL, AS INDICATED BY RECENT GFS AND NAM MOS. THIS MILDNESS
WILL PREVENT ANY CHANGE TO WINTRY TYPE PRECIPITATION THIS PERIOD.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS IN FAIRLY GOOD AGREEMENT WITH SERIES OF SHORT WAVES RUNNING
ALONG THE NORTHERN PERIPHERY OF SUBTROPICAL RIDGE SATURDAY.
PROBLEM IS HOW MUCH PHASING WILL OCCUR...AND HOW FAR NORTH
PRECIPITATION WILL COME AS SURFACE LOWS MOVE ALONG THE FRONT IN
THE MID ATLANTIC STATES.
DID NOT STRAY TOO FAR FROM HPC GRIDS WITH BEST CHANCES OF PRECIP
SATURDAY INTO SUNDAY CHRISTMAS DAY. THERE CAN BE SUFFICIENT COOL
DOWN TO PROVIDE A CHANCE OF MIXED RAIN AND SNOW SHOWERS SOUTH
WITH SNOW SHOWERS IN THE NORTH.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
PER RECENT SURFACE AND RADAR DATA, ALONG WITH HRRR MODEL OUTPUT,
FOR TAF SITES SOUTH OF KFKL AND KDUJ, EXPECT MVFR RAIN AND FOG WITH
SOME INTERLUDES OF IFR THROUGH 16Z. FOR KFKL AND KDUJ, THERE CAN
BE A PERIOD OF IFR SNOW AND FOG THROUGH 16Z.
WITH THE FRONT THEN RETREATING NORTHWARD THIS AFTERNOON, EXPECT
THE RAIN TO DECREASE IN COVERAGE INTO EARLY TONIGHT WITH FLIGHT
CONDITIONS MAINLY MVFR ALL LOCATIONS.
LOW PRESSURE CENTER MOVING NORTHEASTWARD FROM TEXAS TODAY THROUGH
OHIO WEDNESDAY, WILL PROVIDE FREQUENT RAIN SHOWERS LATE TONIGHT
AND DAYTIME WEDNESDAY. THIS WILL LIKELY CAUSE ADDITIONAL BOUTS OF
IFR RESTRICTIONS.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
MVFR WEDNESDAY NIGHT IN LINGERING POST SYSTEM SHOWERS AND CLOUDS
CAN GIVE WAY TO VFR THURSDAY. THE POTENTIAL FOR RESTRICTIONS
THEN RETURNS WITH MIXED PRECIPITATION FRIDAY AND SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
516 AM EST TUE DEC 20 2011
.SYNOPSIS...
A COLD FRONT STALLING ACROSS THE UPPER OHIO VALLEY WILL PROVIDE
RAIN TODAY. HOWEVER, THERE CAN BE A SHORT PERIOD OF WET SNOW THIS
MORNING NORTH OF PITTSBURGH. LOW PRESSURE, COMING NORTHEAST FROM TEXAS,
WILL BRING MILDER TEMPERATURES AND RAIN TONIGHT AND WEDNESDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
PER RECENT RADAR AND SURFACE DATA, COUPLED WITH RECENT HRRR AND
NAM MODEL OUTPUT, EXPECT PRECIPITATION ACROSS THE ENTIRE UPPER
OHIO VALLEY INTO MIDDAY.
THE COLD FRONT MOVING SLOWLY SOUTH FROM THE I-80 CORRIDOR MAY
LOWER SURFACE TEMPERATURES ENOUGH TO CAUSE A CHANGE TO WET SNOW
FOR A TIME THIS MORNING AS FAR SOUTH AS COLUMBIANA COUNTY OHIO,
BEAVER COUNTY, NORTHERN ALLEGHENY COUNTY AND NORTHERN INDIANA
COUNTY PENNSYLVANIA...ALSO ACROSS THE HIGHER MOUNTAIN RIDGES
FARTHER SOUTH. RAIN-WETTED GROUND SHOULD RESULT IN MINIMAL SNOW
ACCUMULATION, IF ANY.
WILL ISSUE STATEMENT REGARDING THE POSSIBILITY OF ICY CONDITIONS
WHERE TEMPERATURES REACH THE FREEZING POINT NEAR THE I-80
CORRIDOR.
EXPECT TEMPERATURES TO BEGIN SLOWLY WARMING LATER THIS MORNING, AS POSTFRONTAL
NORTH WINDS ABATE BEHIND THE STALLING COLD FRONT. THIS WILL
LIKEWISE ALLOW DAYTIME PROCESSES TO RAISE TEMPERATURES ALSO. HENCE
LOCATIONS WITH WET SNOW EARLY THIS MORNING SHOULD SEE IT END BY
MIDDAY. NAM MODEL OUTPUT SHOWS SOUTHEASTERLY WINDS INCREASE AHEAD
OF THE LOW PRESSURE CENTER INCOMING FROM TEXAS, CAUSING A SLOW
WARM UP INTO TONIGHT.
MODELS SHOW THERE MAY BE A BREAK IN THE RAIN SHOWERS EARLY TONIGHT, THEN
AN INCREASE IN RAIN SHOWER COVERAGE LATE TONIGHT AND DAYTIME
WEDNESDAY AS THE LOW PRESSURE CENTER PASSES NORTHEASTWARD THROUGH
OHIO.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
BLEND OF RECENT MODELS SHOWS SCATTERED POST-SYSTEM SHOWERS
CONTINUING IN THE WAKE OF THE EXITING LOW PRESSURE WEDNESDAY NIGHT.
A SECOND LOW PRESSURE SYSTEM, COMING NORTHEAST FROM LOUISIANA,
WILL PROVIDE SHOWERS THURSDAY NIGHT AND FRIDAY.
SOUTHWEST WINDS ALOFT WILL ENSURE TEMPERATURES REMAINING MILDER
THAN NORMAL, AS INDICATED BY RECENT GFS AND NAM MOS. THIS MILDNESS
WILL PREVENT ANY CHANGE TO WINTRY TYPE PRECIPITATION THIS PERIOD.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MODELS IN FAIRLY GOOD AGREEMENT WITH SERIES OF SHORT WAVES RUNNING
ALONG THE NORTHERN PERIPHERY OF SUBTROPICAL RIDGE SATURDAY.
PROBLEM IS HOW MUCH PHASING WILL OCCUR...AND HOW FAR NORTH
PRECIPITATION WILL COME AS SURFACE LOWS MOVE ALONG THE FRONT IN
THE MID ATLANTIC STATES.
DID NOT STRAY TOO FAR FROM HPC GRIDS WITH BEST CHANCES OF PRECIP
SATURDAY INTO SUNDAY CHRISTMAS DAY. THERE CAN BE SUFFICIENT COOL
DOWN TO PROVIDE A CHANCE OF MIXED RAIN AND SNOW SHOWERS SOUTH
WITH SNOW SHOWERS IN THE NORTH.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
PER RECENT SURFACE AND RADAR DATA, ALONG WITH HRRR MODEL OUTPUT,
FOR TAF SITES SOUTH OF KFKL AND KDUJ, EXPECT MVFR RAIN AND FOG WITH
SOME INTERLUDES OF IFR THROUGH 16Z. FOR KFKL AND KDUJ, THERE CAN
BE A PERIOD OF IFR SNOW AND FOG THROUGH 16Z.
WITH THE FRONT THEN RETREATING NORTHWARD THIS AFTERNOON, EXPECT
THE RAIN TO DECREASE IN COVERAGE INTO EARLY TONIGHT WITH FLIGHT
CONDITIONS MAINLY MVFR ALL LOCATIONS.
LOW PRESSURE CENTER MOVING NORTHEASTWARD FROM TEXAS TODAY THROUGH
OHIO WEDNESDAY, WILL PROVIDE FREQUENT RAIN SHOWERS LATE TONIGHT
AND DAYTIME WEDNESDAY. THIS WILL LIKELY CAUSE ADDITIONAL BOUTS OF
IFR RESTRICTIONS.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
MVFR WEDNESDAY NIGHT IN LINGERING POST SYSTEM SHOWERS AND CLOUDS
CAN GIVE WAY TO VFR THURSDAY. THE POTENTIAL FOR RESTRICTIONS
THEN RETURNS WITH MIXED PRECIPITATION FRIDAY AND SATURDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1232 PM EST TUE DEC 20 2011
UPDATED AVIATION DISCUSSION FOR THE 18Z TAFS
.DISCUSSION /TODAY THROUGH MONDAY/... ISSUED AT 411 AM EST
UPPER TROUGH EXITING THE AREA THIS MORNING...PLACING THE AREA UNDER
MORE ZONAL FLOW THROUGH TONIGHT. AT THE SFC...LOW MOVING THROUGH
HUDSON BAY TODAY WILL PUSH A COLD FRONT THROUGH SRN CANADA.
INCREASING GRADIENT AHEAD OF THE FRONT WILL INCREASE WSW WINDS OVER
THE CWA...ESPECIALLY OVER WRN LK SUPERIOR. H925 WINDS /JUST BELOW
THE INVERSION/ SHOULD INCREASE TO 35-40KTS OVER WRN LK SUPERIOR AND
25-30KTS OVER MUCH OF THE CWA. WITH EXPECTED MIXING TOWARDS THAT
LEVEL THIS AFTN WITH MORE SUN...WILL BE BREEZY AT TIMES THIS AFTN
WITH GUSTS TO 25-30MPH...ESPECIALLY NEAR LK SUPERIOR.
PESKY LOW CLOUDS WILL BE THE SHORT TERM FCST CONCERN...AS MODELS
CONTINUE TO STRUGGLE EVEN ACKNOWLEDGING CLOUDS BEING PRESENT. THE
INCREASING H925 WINDS SHOULD HELP PUSH THE LOW CLOUDS NE AND ALSO
AID IN MIXING INTO DRIER AIR ALOFT AND FROM THE WSW. DOWNSLOPING SW
WINDS ALREADY STARTING TO BREAK UP CLOUDS OVER NCNTRL UPPER MI AND
EXPECT THAT TO CONTINUE INTO THE MORNING. RUC STILL LOOKS TO HAVE
THE BEST HANDLE ON THE CLOUDS...AND 06Z RUNS HAVE IT DIMINISHING BY
MID DAY. LLVL WINDS OFF COOLER LK MI WILL LIKELY KEEP CLOUDS HANGING
ON LONGER OVER THE E. IN ADDITION...WITH H850 TEMPS AROUND -9C
CREATING DELTA-T VALUES OF 16 OVER LK MI WILL KEEP LK ENHANCED
CLOUDS OVER FAR SE LUCE/SCHOOLCRAFT COUNTIES THROUGH MUCH OF THE
DAY.
ONCE THE CLOUDS EXIT THE AREA...SHOULD BE A NICE LATE DECEMBER AFTN
WITH PARTLY/MOSTLY SUNNY SKIES /ALTHOUGH A FEW MID CLOUDS COULD PUSH
SE OVER NRN LK SUPERIOR AND AFFECT THE KEWEENAW/ AND HIGHS IN THE
UPPER 20S AND LOWER 30S.
UPPER LOW ASSOCIATED WITH STRONG WINTER STORM IN THE LEE OF THE
CNTRL/SRN ROCKIES WILL SHIFT NE TONIGHT AND MOVE THROUGH THE LOWER
GREAT LAKES ON WED INTO WED NIGHT. WITH THIS SYSTEM PUSHING NE AND
SFC FRONT SLOWLY DROPPING SE THROUGH CANADA AND TOWARDS THE U.S.
BORDER...EXPECT A PORTION OF THE AREA TO BE UNDER THE PINCHED DRY
AIR BETWEEN THE SYSTEMS. LATEST TRENDS IN THE MODELS PUT THIS MORE
OVER THE SE CWA TONIGHT...WHILE THE NW HALF IS UNDER THE INCREASING
CLOUDS WITH THE APPROACHING SFC TROUGH. EXPECT THE CLOUDS TO
CONTINUE SE SLOWLY DURING THE DAY ON WED AS THE SFC TROUGH CONTINUES
IT/S SE PUSH.
PCPN CHANCES INCREASE AS THE SFC TROUGH PUSHES THROUGH LATE WED
NIGHT AND CHANCES WILL CONTINUE ON THURS AS LES DEVELOPS. H850 TEMPS
SHOULD FALL FROM -7C AT 06Z THURS TO -13C AT 18Z AND PUSH DELTA-T
VALUES TOWARDS 17. AS THE COLDER AIR ARRIVES...DEEPER MOISTURE EXITS
AND H850-700 SUBSIDENCE INCREASES /ESPECIALLY IN THE AFTN/...WHICH
CAUSES INVERSION HEIGHTS TO FALL TOWARDS 3-4KFT. THUS...POTENTIAL
FOR MUCH MORE THAT A INCH OR TWO OF LES IS LIMITED ON THURS. DID
BUMP POPS UP SOME FOR THURS FOR THE NNW WIND LOCATIONS...BUT STILL
ONLY PEAKED IT OUT IN THE MID-UPPER CHANCE AREA. ALSO BUMPED UP POPS
SOME FOR THURS NIGHT...TO CHANCES OVER THE E...SINCE LES WILL LIKELY
BE ONGOING AND BEST MOISTURE LOOKS TO BE THERE. WRN CWA IS A LITTLE
MORE UNCERTAIN WITH SFC RIDGE AND DRYING ARRIVING THROUGH THE NIGHT.
WILL GO WITH SLIGHTS FOR MOST OF THE N WIND FAVORED
LOCATIONS...THOUGH WILL GO WITH SOME CHANCES IN THE EVENING OVER THE
HIGHER TERRAIN LOCATIONS.
UPPER TROUGH IN THE NRN STREAM WILL DROP SE OUT OF THE CANADIAN
ROCKIES ON WED AND THROUGH THE UPPER GREAT LAKES THURS THROUGH FRI.
STILL SOME DIFFERENCES IN THE MODELS ON POTENTIALLY CLOSING OFF THE
SRN EXTENT OF THE UPPER TROUGH OVER THE CNTRL PLAINS FRI...WHICH
WOULD ALLOW WEAK UPPER RIDGING TO MOVE INTO THE WRN GREAT LKS
EARLIER ON FRI NIGHT AND CONTINUE INTO SAT. EITHER WAY...CWA WILL
LIKELY BE BETWEEN SYSTEMS AND HAVE SFC HIGH OVER THE AREA FRI NIGHT
INTO SAT.
EXPECT LINGERING LES TO DIMINISH AND PUSH OFFSHORE OVER THE ERN CWA
ON FRI...AS H850 WAA PUSHES TEMPS TOWARDS -8C AND LLVL WINDS BACK TO
THE WSW. AT THE SAME TIME SHORTWAVE MOVING THROUGH THE NRN STREAM IN
CNTRL/NRN ONTARIO SHOULD ONLY BRUSH HIGH CLOUDS OVER NRN LK
SUPERIOR...ALTHOUGH 00Z GFS/GEM HAS TRENDED FARTHER S WITH WITH WAVE
AND BRUSHES PCPN OVER NRN LK SUPERIOR. SWRLY FLOW AND DRY AIR ALOFT
SHOULD KEEP TEMPS IN CHECK WITH CLEAR SKIES ON FRI NIGHT AND WILL GO
WITH ABOVE NORMAL LOWS. DRY AIR ABOVE THE STRONG INVERSION AROUND
H925 SHOULD KEEP SKIES MOSTLY SUNNY ON SAT OTHER THAN SOME PASSING
HIGH CLOUDS. TEMPS ARE UNCERTAIN THIS FAR OUT AND WILL LEAN TOWARDS
A CONSENSUS FOR HIGHS. THAT BEING SAID...CLEAR SKIES AND SW WINDS
FAVOR WARMER TEMPS IN DOWNSLOPE AREAS NEAR LK SUPERIOR...SO DID
ADJUST THOSE AREAS UP A FEW DEGREES.
NRN STREAM TROUGH IS STILL SHOWN ON THE EXTENDED MODELS TO AFFECT
THE AREA SUN INTO MON. SFC TROUGH ASSOCIATED WITH LOW MOVING THROUGH
HUDSON BAY SHOULD DRAG A SFC TROUGH ACROSS THE CWA SAT NIGHT OR SUN
/12Z ECMWF AND 00Z GEM ARE THE FASTER SOLNS/. AS HAS BEEN THE CASE
WITH THE SERIES OF NRN STREAM WAVES...MOISTURE/FORCING ALONG THE
FRONT APPEARS TO BE LIMITED SO WILL CONTINUE SLIGHTS/LOW CHANCES
WITH THE FRONTAL PASSAGE. H850 TEMPS AROUND -15C AND POST FRONTAL
LLVL MOISTURE SHOULD LEAD TO LES IN NW WIND FAVORED LOCATIONS SUN
AND BUMPED UP POPS FROM THE CONSENSUS AND WILL CONTINUE CHANCE POPS
THROUGH SUN NIGHT. 00Z GFS SOUNDINGS WOULD SUPPORT A CHANCE OF
SEEING AT LEAST FEW INCHES OF SNOW ACCUMULATIONS NNW SNOWBELTS FOR
XMAS AFTN/EVENING. ECMWF ON THE OTHERHAND QUICKLY PULLS DRIER AIR
INTO THE REGION SUN AFTN/NIGHT WITH THE ARRIVAL OF THE SFC RIDGE.
ANOTHER NRN STREAM SHORTWAVE WAVE LOOKS TO BRUSH LK SUPERIOR ON
MN...BUT WITH OVERALL WEAK WAVE AND LIMITED MOISTURE WILL ONLY GO
SLIGHT POPS.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/...
MVFR CIGS HAVE LIFTED FROM KSAW AND WOULD EXPECT VFR CONDITIONS TO
PERSIST THRU ALL TAF SITES THROUGH THE END OF THIS FCST PERIOD.
TIGHTENING PRES GRADIENT TODAY WILL RESULT IN GUSTY SW WINDS TO
AROUND 25KT. EXPECT LLWS TO DEVELOP THIS EVENING AS WINDS DECOUPLE
SOMEWHAT. LOOK FOR SOME LOWER VFR CIGS 4-5KFT TO MOVE INTO KIWD AND
KCMX BY LATE WED MORNING AS WINDS SHIFT WRLY BEHIND COLD FRONTAL
PASSAGE.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
DEEP LOW PRES MOVING E TO HUDSON BAY WILL BRING ANOTHER ROUND OF SW
GALES TO MUCH OF LAKE SUPERIOR TODAY THRU THIS EVENING. SW WIND
DIRECTION WILL FAVOR THE AREA BTWN THE KEWEENAW AND ISLE ROYALE FOR
STRONGEST WINDS (GUSTS TO 40-45KT). GALES WILL END LATER TONIGHT
AS PRES GRADIENT WEAKENS. WINDS WILL BE BLO 25KT WED THRU FRI THOUGH
THERE MAY BE A PERIOD OF 20-30KT WINDS OVER CNTRL LAKE SUPERIOR THU
MORNING IN THE WAKE OF A PASSING COLD FRONT. ANOTHER LOW PRES SYSTEM
TRACKING E TO HUDSON BAY COULD BRING A PERIOD OF SW WINDS UP TO 30KT
OVER PORTIONS OF WEST AND NCNTRL LAKE SUPERIOR LATE FRI NIGHT INTO
SAT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...NONE.
LAKE SUPERIOR...
GALE WARNING FROM 1 PM THIS AFTERNOON TO 1 AM EST WEDNESDAY FOR
LSZ267.
GALE WARNING FROM 9 AM THIS MORNING TO 1 AM EST WEDNESDAY FOR
LSZ266.
GALE WARNING UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT FOR LSZ162.
GALE WARNING UNTIL 3 AM EST WEDNESDAY FOR LSZ263-264.
LAKE MICHIGAN...NONE.
&&
$$
DISCUSSION...SRF
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
630 AM EST TUE DEC 20 2011
UPDATED AVIATION DISCUSSION FOR THE 12Z TAFS
.DISCUSSION /TODAY THROUGH MONDAY/... ISSUED AT 411 AM EST
UPPER TROUGH EXITING THE AREA THIS MORNING...PLACING THE AREA UNDER
MORE ZONAL FLOW THROUGH TONIGHT. AT THE SFC...LOW MOVING THROUGH
HUDSON BAY TODAY WILL PUSH A COLD FRONT THROUGH SRN CANADA.
INCREASING GRADIENT AHEAD OF THE FRONT WILL INCREASE WSW WINDS OVER
THE CWA...ESPECIALLY OVER WRN LK SUPERIOR. H925 WINDS /JUST BELOW
THE INVERSION/ SHOULD INCREASE TO 35-40KTS OVER WRN LK SUPERIOR AND
25-30KTS OVER MUCH OF THE CWA. WITH EXPECTED MIXING TOWARDS THAT
LEVEL THIS AFTN WITH MORE SUN...WILL BE BREEZY AT TIMES THIS AFTN
WITH GUSTS TO 25-30MPH...ESPECIALLY NEAR LK SUPERIOR.
PESKY LOW CLOUDS WILL BE THE SHORT TERM FCST CONCERN...AS MODELS
CONTINUE TO STRUGGLE EVEN ACKNOWLEDGING CLOUDS BEING PRESENT. THE
INCREASING H925 WINDS SHOULD HELP PUSH THE LOW CLOUDS NE AND ALSO
AID IN MIXING INTO DRIER AIR ALOFT AND FROM THE WSW. DOWNSLOPING SW
WINDS ALREADY STARTING TO BREAK UP CLOUDS OVER NCNTRL UPPER MI AND
EXPECT THAT TO CONTINUE INTO THE MORNING. RUC STILL LOOKS TO HAVE
THE BEST HANDLE ON THE CLOUDS...AND 06Z RUNS HAVE IT DIMINISHING BY
MID DAY. LLVL WINDS OFF COOLER LK MI WILL LIKELY KEEP CLOUDS HANGING
ON LONGER OVER THE E. IN ADDITION...WITH H850 TEMPS AROUND -9C
CREATING DELTA-T VALUES OF 16 OVER LK MI WILL KEEP LK ENHANCED
CLOUDS OVER FAR SE LUCE/SCHOOLCRAFT COUNTIES THROUGH MUCH OF THE
DAY.
ONCE THE CLOUDS EXIT THE AREA...SHOULD BE A NICE LATE DECEMBER AFTN
WITH PARTLY/MOSTLY SUNNY SKIES /ALTHOUGH A FEW MID CLOUDS COULD PUSH
SE OVER NRN LK SUPERIOR AND AFFECT THE KEWEENAW/ AND HIGHS IN THE
UPPER 20S AND LOWER 30S.
UPPER LOW ASSOCIATED WITH STRONG WINTER STORM IN THE LEE OF THE
CNTRL/SRN ROCKIES WILL SHIFT NE TONIGHT AND MOVE THROUGH THE LOWER
GREAT LAKES ON WED INTO WED NIGHT. WITH THIS SYSTEM PUSHING NE AND
SFC FRONT SLOWLY DROPPING SE THROUGH CANADA AND TOWARDS THE U.S.
BORDER...EXPECT A PORTION OF THE AREA TO BE UNDER THE PINCHED DRY
AIR BETWEEN THE SYSTEMS. LATEST TRENDS IN THE MODELS PUT THIS MORE
OVER THE SE CWA TONIGHT...WHILE THE NW HALF IS UNDER THE INCREASING
CLOUDS WITH THE APPROACHING SFC TROUGH. EXPECT THE CLOUDS TO
CONTINUE SE SLOWLY DURING THE DAY ON WED AS THE SFC TROUGH CONTINUES
IT/S SE PUSH.
PCPN CHANCES INCREASE AS THE SFC TROUGH PUSHES THROUGH LATE WED
NIGHT AND CHANCES WILL CONTINUE ON THURS AS LES DEVELOPS. H850 TEMPS
SHOULD FALL FROM -7C AT 06Z THURS TO -13C AT 18Z AND PUSH DELTA-T
VALUES TOWARDS 17. AS THE COLDER AIR ARRIVES...DEEPER MOISTURE EXITS
AND H850-700 SUBSIDENCE INCREASES /ESPECIALLY IN THE AFTN/...WHICH
CAUSES INVERSION HEIGHTS TO FALL TOWARDS 3-4KFT. THUS...POTENTIAL
FOR MUCH MORE THAT A INCH OR TWO OF LES IS LIMITED ON THURS. DID
BUMP POPS UP SOME FOR THURS FOR THE NNW WIND LOCATIONS...BUT STILL
ONLY PEAKED IT OUT IN THE MID-UPPER CHANCE AREA. ALSO BUMPED UP POPS
SOME FOR THURS NIGHT...TO CHANCES OVER THE E...SINCE LES WILL LIKELY
BE ONGOING AND BEST MOISTURE LOOKS TO BE THERE. WRN CWA IS A LITTLE
MORE UNCERTAIN WITH SFC RIDGE AND DRYING ARRIVING THROUGH THE NIGHT.
WILL GO WITH SLIGHTS FOR MOST OF THE N WIND FAVORED
LOCATIONS...THOUGH WILL GO WITH SOME CHANCES IN THE EVENING OVER THE
HIGHER TERRAIN LOCATIONS.
UPPER TROUGH IN THE NRN STREAM WILL DROP SE OUT OF THE CANADIAN
ROCKIES ON WED AND THROUGH THE UPPER GREAT LAKES THURS THROUGH FRI.
STILL SOME DIFFERENCES IN THE MODELS ON POTENTIALLY CLOSING OFF THE
SRN EXTENT OF THE UPPER TROUGH OVER THE CNTRL PLAINS FRI...WHICH
WOULD ALLOW WEAK UPPER RIDGING TO MOVE INTO THE WRN GREAT LKS
EARLIER ON FRI NIGHT AND CONTINUE INTO SAT. EITHER WAY...CWA WILL
LIKELY BE BETWEEN SYSTEMS AND HAVE SFC HIGH OVER THE AREA FRI NIGHT
INTO SAT.
EXPECT LINGERING LES TO DIMINISH AND PUSH OFFSHORE OVER THE ERN CWA
ON FRI...AS H850 WAA PUSHES TEMPS TOWARDS -8C AND LLVL WINDS BACK TO
THE WSW. AT THE SAME TIME SHORTWAVE MOVING THROUGH THE NRN STREAM IN
CNTRL/NRN ONTARIO SHOULD ONLY BRUSH HIGH CLOUDS OVER NRN LK
SUPERIOR...ALTHOUGH 00Z GFS/GEM HAS TRENDED FARTHER S WITH WITH WAVE
AND BRUSHES PCPN OVER NRN LK SUPERIOR. SWRLY FLOW AND DRY AIR ALOFT
SHOULD KEEP TEMPS IN CHECK WITH CLEAR SKIES ON FRI NIGHT AND WILL GO
WITH ABOVE NORMAL LOWS. DRY AIR ABOVE THE STRONG INVERSION AROUND
H925 SHOULD KEEP SKIES MOSTLY SUNNY ON SAT OTHER THAN SOME PASSING
HIGH CLOUDS. TEMPS ARE UNCERTAIN THIS FAR OUT AND WILL LEAN TOWARDS
A CONSENSUS FOR HIGHS. THAT BEING SAID...CLEAR SKIES AND SW WINDS
FAVOR WARMER TEMPS IN DOWNSLOPE AREAS NEAR LK SUPERIOR...SO DID
ADJUST THOSE AREAS UP A FEW DEGREES.
NRN STREAM TROUGH IS STILL SHOWN ON THE EXTENDED MODELS TO AFFECT
THE AREA SUN INTO MON. SFC TROUGH ASSOCIATED WITH LOW MOVING THROUGH
HUDSON BAY SHOULD DRAG A SFC TROUGH ACROSS THE CWA SAT NIGHT OR SUN
/12Z ECMWF AND 00Z GEM ARE THE FASTER SOLNS/. AS HAS BEEN THE CASE
WITH THE SERIES OF NRN STREAM WAVES...MOISTURE/FORCING ALONG THE
FRONT APPEARS TO BE LIMITED SO WILL CONTINUE SLIGHTS/LOW CHANCES
WITH THE FRONTAL PASSAGE. H850 TEMPS AROUND -15C AND POST FRONTAL
LLVL MOISTURE SHOULD LEAD TO LES IN NW WIND FAVORED LOCATIONS SUN
AND BUMPED UP POPS FROM THE CONSENSUS AND WILL CONTINUE CHANCE POPS
THROUGH SUN NIGHT. 00Z GFS SOUNDINGS WOULD SUPPORT A CHANCE OF
SEEING AT LEAST FEW INCHES OF SNOW ACCUMULATIONS NNW SNOWBELTS FOR
XMAS AFTN/EVENING. ECMWF ON THE OTHERHAND QUICKLY PULLS DRIER AIR
INTO THE REGION SUN AFTN/NIGHT WITH THE ARRIVAL OF THE SFC RIDGE.
ANOTHER NRN STREAM SHORTWAVE WAVE LOOKS TO BRUSH LK SUPERIOR ON
MN...BUT WITH OVERALL WEAK WAVE AND LIMITED MOISTURE WILL ONLY GO
SLIGHT POPS.
&&
.AVIATION /FOR THE 12Z TAF ISSUANCE/...
MVFR CIGS CONTINUE TO HANG ON LONGER THAN SUGGESTED BY GUIDANCE.
WITH SFC HIGH PRES RIDGE AXIS SLIPPING SE OF THE AREA...RESULTING IN
INCREASING SW WINDS...EXPECT LOWER CLOUDS TO CLEAR OUT BTWN MID
MORNING AND EARLY AFTN PER TRENDS NOTED ON SATELLITE IMAGERY. VFR
CONDITIONS WILL THEN PERSIST THRU THE END OF THIS FCST PERIOD.
TIGHTENING PRES GRADIENT TODAY WILL RESULT IN GUSTY WINDS TO AROUND
25KT. LLWS MAY DEVELOP THIS EVENING DEPENDING ON DEGREE OF
DECOUPLING THAT OCCURS. RIGHT NOW...EXPECT WINDS TO RETAIN SOME
GUSTINESS THRU THE EVENING.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
DEEP LOW PRES MOVING E TO HUDSON BAY WILL BRING ANOTHER ROUND OF SW
GALES TO MUCH OF LAKE SUPERIOR TODAY THRU THIS EVENING. SW WIND
DIRECTION WILL FAVOR THE AREA BTWN THE KEWEENAW AND ISLE ROYALE FOR
STRONGEST WINDS (GUSTS TO 40-45KT). GALES WILL END LATER TONIGHT
AS PRES GRADIENT WEAKENS. WINDS WILL BE BLO 25KT WED THRU FRI THOUGH
THERE MAY BE A PERIOD OF 20-30KT WINDS OVER CNTRL LAKE SUPERIOR THU
MORNING IN THE WAKE OF A PASSING COLD FRONT. ANOTHER LOW PRES SYSTEM
TRACKING E TO HUDSON BAY COULD BRING A PERIOD OF SW WINDS UP TO 30KT
OVER PORTIONS OF WEST AND NCNTRL LAKE SUPERIOR LATE FRI NIGHT INTO
SAT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...NONE.
LAKE SUPERIOR...
GALE WARNING FROM 1 PM THIS AFTERNOON TO 1 AM EST WEDNESDAY FOR
LSZ267.
GALE WARNING FROM 9 AM THIS MORNING TO 1 AM EST WEDNESDAY FOR
LSZ266.
GALE WARNING UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT FOR LSZ162.
GALE WARNING UNTIL 3 AM EST WEDNESDAY FOR LSZ263-264.
LAKE MICHIGAN...NONE.
&&
$$
DISCUSSION...SRF
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
411 AM EST TUE DEC 20 2011
.DISCUSSION /TODAY THROUGH MONDAY/...
UPPER TROUGH EXITING THE AREA THIS MORNING...PLACING THE AREA UNDER
MORE ZONAL FLOW THROUGH TONIGHT. AT THE SFC...LOW MOVING THROUGH
HUDSON BAY TODAY WILL PUSH A COLD FRONT THROUGH SRN CANADA.
INCREASING GRADIENT AHEAD OF THE FRONT WILL INCREASE WSW WINDS OVER
THE CWA...ESPECIALLY OVER WRN LK SUPERIOR. H925 WINDS /JUST BELOW
THE INVERSION/ SHOULD INCREASE TO 35-40KTS OVER WRN LK SUPERIOR AND
25-30KTS OVER MUCH OF THE CWA. WITH EXPECTED MIXING TOWARDS THAT
LEVEL THIS AFTN WITH MORE SUN...WILL BE BREEZY AT TIMES THIS AFTN
WITH GUSTS TO 25-30MPH...ESPECIALLY NEAR LK SUPERIOR.
PESKY LOW CLOUDS WILL BE THE SHORT TERM FCST CONCERN...AS MODELS
CONTINUE TO STRUGGLE EVEN ACKNOWLEDGING CLOUDS BEING PRESENT. THE
INCREASING H925 WINDS SHOULD HELP PUSH THE LOW CLOUDS NE AND ALSO
AID IN MIXING INTO DRIER AIR ALOFT AND FROM THE WSW. DOWNSLOPING SW
WINDS ALREADY STARTING TO BREAK UP CLOUDS OVER NCNTRL UPPER MI AND
EXPECT THAT TO CONTINUE INTO THE MORNING. RUC STILL LOOKS TO HAVE
THE BEST HANDLE ON THE CLOUDS...AND 06Z RUNS HAVE IT DIMINISHING BY
MID DAY. LLVL WINDS OFF COOLER LK MI WILL LIKELY KEEP CLOUDS HANGING
ON LONGER OVER THE E. IN ADDITION...WITH H850 TEMPS AROUND -9C
CREATING DELTA-T VALUES OF 16 OVER LK MI WILL KEEP LK ENHANCED
CLOUDS OVER FAR SE LUCE/SCHOOLCRAFT COUNTIES THROUGH MUCH OF THE
DAY.
ONCE THE CLOUDS EXIT THE AREA...SHOULD BE A NICE LATE DECEMBER AFTN
WITH PARTLY/MOSTLY SUNNY SKIES /ALTHOUGH A FEW MID CLOUDS COULD PUSH
SE OVER NRN LK SUPERIOR AND AFFECT THE KEWEENAW/ AND HIGHS IN THE
UPPER 20S AND LOWER 30S.
UPPER LOW ASSOCIATED WITH STRONG WINTER STORM IN THE LEE OF THE
CNTRL/SRN ROCKIES WILL SHIFT NE TONIGHT AND MOVE THROUGH THE LOWER
GREAT LAKES ON WED INTO WED NIGHT. WITH THIS SYSTEM PUSHING NE AND
SFC FRONT SLOWLY DROPPING SE THROUGH CANADA AND TOWARDS THE U.S.
BORDER...EXPECT A PORTION OF THE AREA TO BE UNDER THE PINCHED DRY
AIR BETWEEN THE SYSTEMS. LATEST TRENDS IN THE MODELS PUT THIS MORE
OVER THE SE CWA TONIGHT...WHILE THE NW HALF IS UNDER THE INCREASING
CLOUDS WITH THE APPROACHING SFC TROUGH. EXPECT THE CLOUDS TO
CONTINUE SE SLOWLY DURING THE DAY ON WED AS THE SFC TROUGH CONTINUES
IT/S SE PUSH.
PCPN CHANCES INCREASE AS THE SFC TROUGH PUSHES THROUGH LATE WED
NIGHT AND CHANCES WILL CONTINUE ON THURS AS LES DEVELOPS. H850 TEMPS
SHOULD FALL FROM -7C AT 06Z THURS TO -13C AT 18Z AND PUSH DELTA-T
VALUES TOWARDS 17. AS THE COLDER AIR ARRIVES...DEEPER MOISTURE EXITS
AND H850-700 SUBSIDENCE INCREASES /ESPECIALLY IN THE AFTN/...WHICH
CAUSES INVERSION HEIGHTS TO FALL TOWARDS 3-4KFT. THUS...POTENTIAL
FOR MUCH MORE THAT A INCH OR TWO OF LES IS LIMITED ON THURS. DID
BUMP POPS UP SOME FOR THURS FOR THE NNW WIND LOCATIONS...BUT STILL
ONLY PEAKED IT OUT IN THE MID-UPPER CHANCE AREA. ALSO BUMPED UP POPS
SOME FOR THURS NIGHT...TO CHANCES OVER THE E...SINCE LES WILL LIKELY
BE ONGOING AND BEST MOISTURE LOOKS TO BE THERE. WRN CWA IS A LITTLE
MORE UNCERTAIN WITH SFC RIDGE AND DRYING ARRIVING THROUGH THE NIGHT.
WILL GO WITH SLIGHTS FOR MOST OF THE N WIND FAVORED
LOCATIONS...THOUGH WILL GO WITH SOME CHANCES IN THE EVENING OVER THE
HIGHER TERRAIN LOCATIONS.
UPPER TROUGH IN THE NRN STREAM WILL DROP SE OUT OF THE CANADIAN
ROCKIES ON WED AND THROUGH THE UPPER GREAT LAKES THURS THROUGH FRI.
STILL SOME DIFFERENCES IN THE MODELS ON POTENTIALLY CLOSING OFF THE
SRN EXTENT OF THE UPPER TROUGH OVER THE CNTRL PLAINS FRI...WHICH
WOULD ALLOW WEAK UPPER RIDGING TO MOVE INTO THE WRN GREAT LKS
EARLIER ON FRI NIGHT AND CONTINUE INTO SAT. EITHER WAY...CWA WILL
LIKELY BE BETWEEN SYSTEMS AND HAVE SFC HIGH OVER THE AREA FRI NIGHT
INTO SAT.
EXPECT LINGERING LES TO DIMINISH AND PUSH OFFSHORE OVER THE ERN CWA
ON FRI...AS H850 WAA PUSHES TEMPS TOWARDS -8C AND LLVL WINDS BACK TO
THE WSW. AT THE SAME TIME SHORTWAVE MOVING THROUGH THE NRN STREAM IN
CNTRL/NRN ONTARIO SHOULD ONLY BRUSH HIGH CLOUDS OVER NRN LK
SUPERIOR...ALTHOUGH 00Z GFS/GEM HAS TRENDED FARTHER S WITH WITH WAVE
AND BRUSHES PCPN OVER NRN LK SUPERIOR. SWRLY FLOW AND DRY AIR ALOFT
SHOULD KEEP TEMPS IN CHECK WITH CLEAR SKIES ON FRI NIGHT AND WILL GO
WITH ABOVE NORMAL LOWS. DRY AIR ABOVE THE STRONG INVERSION AROUND
H925 SHOULD KEEP SKIES MOSTLY SUNNY ON SAT OTHER THAN SOME PASSING
HIGH CLOUDS. TEMPS ARE UNCERTAIN THIS FAR OUT AND WILL LEAN TOWARDS
A CONSENSUS FOR HIGHS. THAT BEING SAID...CLEAR SKIES AND SW WINDS
FAVOR WARMER TEMPS IN DOWNSLOPE AREAS NEAR LK SUPERIOR...SO DID
ADJUST THOSE AREAS UP A FEW DEGREES.
NRN STREAM TROUGH IS STILL SHOWN ON THE EXTENDED MODELS TO AFFECT
THE AREA SUN INTO MON. SFC TROUGH ASSOCIATED WITH LOW MOVING THROUGH
HUDSON BAY SHOULD DRAG A SFC TROUGH ACROSS THE CWA SAT NIGHT OR SUN
/12Z ECMWF AND 00Z GEM ARE THE FASTER SOLNS/. AS HAS BEEN THE CASE
WITH THE SERIES OF NRN STREAM WAVES...MOISTURE/FORCING ALONG THE
FRONT APPEARS TO BE LIMITED SO WILL CONTINUE SLIGHTS/LOW CHANCES
WITH THE FRONTAL PASSAGE. H850 TEMPS AROUND -15C AND POST FRONTAL
LLVL MOISTURE SHOULD LEAD TO LES IN NW WIND FAVORED LOCATIONS SUN
AND BUMPED UP POPS FROM THE CONSENSUS AND WILL CONTINUE CHANCE POPS
THROUGH SUN NIGHT. 00Z GFS SOUNDINGS WOULD SUPPORT A CHANCE OF
SEEING AT LEAST FEW INCHES OF SNOW ACCUMULATIONS NNW SNOWBELTS FOR
XMAS AFTN/EVENING. ECMWF ON THE OTHERHAND QUICKLY PULLS DRIER AIR
INTO THE REGION SUN AFTN/NIGHT WITH THE ARRIVAL OF THE SFC RIDGE.
ANOTHER NRN STREAM SHORTWAVE WAVE LOOKS TO BRUSH LK SUPERIOR ON
MN...BUT WITH OVERALL WEAK WAVE AND LIMITED MOISTURE WILL ONLY GO
SLIGHT POPS.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
MVFR CIGS HAVE PERSISTED SIGNIFICANTLY LONGER THAN GUIDANCE OR WHAT
NAM/GFS LOW LEVEL RH PROGS WOULD SUGGEST. HOWEVER...EXPECT SKIES TO
FINALLY CLEAR EARLY TODAY AS THE HIGH PRES RIDGE AXIS DROPS SE
THRU THE AREA AND WINDS SHIFT TO THE SOUTHWEST AND BRINGS DRIER AIR
TOWARD THE AREA FROM THE UPPER MS VALLEY...PER RUC PROGS. SW
GRADIENT WINDS WILL INCREASE TODAY WITH GUSTS AROUND 25 KT BY LATE
MORNING/EARLY AFTERNOON.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
DEEP LOW PRES MOVING E TO HUDSON BAY WILL BRING ANOTHER ROUND OF SW
GALES TO MUCH OF LAKE SUPERIOR TODAY THRU THIS EVENING. SW WIND
DIRECTION WILL FAVOR THE AREA BTWN THE KEWEENAW AND ISLE ROYALE FOR
STRONGEST WINDS (GUSTS TO 40-45KT). GALES WILL END LATER TONIGHT
AS PRES GRADIENT WEAKENS. WINDS WILL BE BLO 25KT WED THRU FRI THOUGH
THERE MAY BE A PERIOD OF 20-30KT WINDS OVER CNTRL LAKE SUPERIOR THU
MORNING IN THE WAKE OF A PASSING COLD FRONT. ANOTHER LOW PRES SYSTEM
TRACKING E TO HUDSON BAY COULD BRING A PERIOD OF SW WINDS UP TO 30KT
OVER PORTIONS OF WEST AND NCNTRL LAKE SUPERIOR LATE FRI NIGHT INTO
SAT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 1 PM THIS AFTERNOON TO 1 AM EST WEDNESDAY FOR
LSZ267.
GALE WARNING FROM 9 AM THIS MORNING TO 1 AM EST WEDNESDAY FOR
LSZ266.
GALE WARNING UNTIL MIDNIGHT EST /11 PM CST/ TONIGHT FOR LSZ162.
GALE WARNING UNTIL 3 AM EST WEDNESDAY FOR LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
DISCUSSION...SRF
AVIATION...JLB
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1214 AM EST TUE DEC 20 2011
UPDATED FOR 06Z AVIATION DISCUSSION
.SHORT TERM /TONIGHT AND TUESDAY/... ISSUED AT 337 PM EST
HIGH PRESSURE RIDGE SLIDING OVER THE AREA TONIGHT SHOULD BRING AN
END TO THE LES/FLURRIES OVER THE E THIS EVENING. GIVEN WIDESPREAD
STRATOCU DECK IN PLACE ACROSS NRN MN...WI AND ONTARIO...CLOUDS MAY
PERSIST A BIT LONGER INTO AT LEAST THE EARLY EVENING
HRS...ESPECIALLY OVER ERN COUNTIES...WITH A NW FLOW. STILL EXPECT
DECREASING CLOUDS BY LATE EVENING WITH ARRIVAL OF SFC RDG AXIS AND
ASSOC SUBSIDENCE. WITH THE DECREASING CLOUDS AND WINDS...SHOULD BE A
COLD NIGHT OVER THE INTERIOR LOCATIONS. PWATS AROUND 35 PERCENT OF
NORMAL WILL HELP ENHANCE RADIATIONAL COOLING SO WENT ON THE LOWER
END OF MODEL MOS GUIDANCE WITH LOWS IN THE MID SINGLE DIGITS ABOVE
ZERO OVER THE INTERIOR W/CNTRL. WINDS WILL INCREASE SOME OVER THE
FAR W LATE IN THE NIGHT AHEAD OF THE NEXT WAVE...WHICH COULD LEAD TO
A RISE IN TEMPS LATE THERE.
NRN STREAM SHORTWAVE AND ASSOCIATED LOW WILL BE MOVING THROUGH FAR
NRN ONTARIO/HUDSON BAY REGION ON TUESDAY. THIS WILL RESULT IN DRY
CONDITIONS ACROSS UPR MI ON TUESDAY BUT FALLING PRES NORTH OF LAKE
SUPERIOR SHOULD ALLOW WSW TO PICK UP AND BCM GUSTY ESPECIALLY ACROSS
THE NRN TIER OF THE FCST AREA. SHOULD BE ANOTHER ABOVE NORMAL TEMP
DAY (UPPER 20S AND LOWER 30S) UNDER A MOSTLY SUNNY SKY.
.LONG TERM /00Z WED THROUGH NEXT SUN/...
MODELS HAVE CONTINUED THE FASTER TREND WITH MERGING THE SRN STREAM
UPPER LOW CURRENTLY OVER THE SWRN CONUS WITH THE NRN STREAM ON WED
OVER THE LOWER GREAT LAKES. WITH THE APPROACHING NRN STREAM WAVE
OVER MANITOBA/SASK...AREA SHOULD BE UNDER THE INFLUENCE OF A WEAK
SFC TROUGH DROPPING S FROM ONTARIO. MOSTLY CLEAR SKIES AT 00Z WED
WILL GIVE WAY TO CLOUDS MOVING IN FROM THE NW THROUGH WED. WITH
MODELS MOVING THE SFC TROUGH AND LOW LEVEL MOISTURE IN FAST...HAVE
INCREASED HOW FAST THE CLOUDS MOVE IN. MOISTURE/FORCING IS WEAK WITH
THE PASSAGE OF THE TROUGH...SO WILL CONTINUE SLIGHT CHANCE POPS OVER
WRN LK SUPERIOR IN THE AFTN AND SLIGHT/LOW CHANCE POPS ALONG THE
FRONT WED NIGHT.
UPPER TROUGH THEN SWEEPS ACROSS THE AREA LATE WED NIGHT INTO
FRI...BRINGING A BETTER CHANCE FOR SNOW BEHIND THE FRONT. 850MB
TEMPS LOOK TO FALL TO AROUND -12C BY 18Z THU...WHICH WOULD CREATE
LARGE ENOUGH DELTA-T VALUES FOR LES. 800-650MB SUBSIDENCE AND DRY
AIR WILL LIMIT THE INVERSION HEIGHTS TO 4KFT. SHOULD BE DECENT LLVL
MOISTURE TO WORK WITH BELOW THE INVERSION...SO CONTINUED WITH CHANCE
POPS. WITH THE FORCING BELOW THE DGZ /CLOUD TOPS ONLY REACH -15C/
EXPECT SNOW RATIOS TO BE IN THE LOW TEENS AND WILL LIKELY ONLY SEE A
LIGHT DUSTING FOR AREAS FAVORED BY A NNW WIND.
UPPER TROUGH STARTS TO SHIFT E ON FRI AS SFC HIGH PUSHES OVER THE
AREA. DRIER AIR ASSOCIATED WITH THE HIGH WILL LEAD TO DIMINISHING
LES POPS THURS NIGHT WEST AND DURING THE DAY FRI EAST...AS WINDS
BECOME ANTICYCLONIC. MAY SEE WEAK UPPER RIDGING ON SAT /AS SHOWN BY
THE 12Z/19 GFS/...HOWEVER...THERE IS A GOOD DEAL OF UNCERTAINTY AS
THE 00Z/19 ECMWF SHOWS A SHARP UPPER TROUGH OVER THE CWA AT THE SAME
TIME. THE NEXT NRN STREAM TROUGH TO AFFECT THE AREA WILL MOVE IN ON
SAT NIGHT INTO SUN. FORCING/MOISTURE LOOK TO BE LIMITED ALONG THE
FRONT AND THE BEST POTENTIAL FOR PCPN WILL COME ON SUN WITH LES...AS
H850 TEMPS FALL TOWARDS -13C.
BROAD UPPER RIDGING LOOKS TO MOVE OVER THE WRN HALF OF THE CONUS ON
MONDAY AS THE UPPER TROUGH MOVES EAST OF THE CWA...PUTTING THE CWA
UNDER GENERAL NW FLOW ALOFT. THERE IS A SIGNIFICANT AMOUNT OF
UNCERTAINTY FOR SUNDAY NIGHT INTO MONDAY...WITH MODELS HAVING BAD
RUN TO RUN CONTINUITY AND MODEL DISAGREEMENT. OVERALL...EXPECT
DIMINISHING LES AS 850MB TEMPS WARM AND FLOW GENERALLY BECOMES MORE
ANTICYCLONIC.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
MVFR CIGS HAVE PERSISTED SIGNIFICANTLY LONGER THAN GUIDANCE OR WHAT
NAM/GFS LOW LEVEL RH PROGS WOULD SUGGEST. HOWEVER...EXPECT SKIES TO
FINALLY CLEAR EARLY TODAY AS THE HIGH PRES RIDGE AXIS DROPS SE
THRU THE AREA AND WINDS SHIFT TO THE SOUTHWEST AND BRINGS DRIER AIR
TOWARD THE AREA FROM THE UPPER MS VALLEY...PER RUC PROGS. SW
GRADIENT WINDS WILL INCREASE TODAY WITH GUSTS AROUND 25 KT BY LATE
MORNING/EARLY AFTERNOON.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
WINDS WILL DIMINISH BLO 25 KT TONIGHT AS HIGH PRES QUICKLY PASSES
ACROSS THE GREAT LAKES. DEEP LOW PRES MOVING E TO HUDSON BAY EARLY
TUE WILL LIKELY BRING ANOTHER ROUND OF SW GALES TO PORTIONS OF LAKE
SUPERIOR...MAINLY THE W HALF. SW WIND DIRECTION WILL FAVOR THE AREA
BTWN THE KEWEENAW AND ISLE ROYALE FOR STRONGEST WINDS TUE (GUSTS TO
AROUND 40KT). GALES WILL END TUE NIGHT AS PRES GRADIENT WEAKENS.
WINDS WILL BE BLO 25KT WED THRU FRI. ANOTHER LOW PRES SYSTEM
TRACKING ACROSS HUDSON BAY COULD BRING A PERIOD OF SW WINDS TO 30 KT
OVER WEST AND NORTH CENTRAL LAKE SUPERIOR FRI NIGHT INTO SATURDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...NONE.
LAKE SUPERIOR...
GALE WARNING FROM 9 AM TUESDAY TO 1 AM EST WEDNESDAY FOR LSZ266.
GALE WARNING FROM 7 AM EST /6 AM CST/ TUESDAY TO MIDNIGHT EST
/11 PM CST/ TUESDAY NIGHT FOR LSZ162.
GALE WARNING FROM 7 AM TUESDAY TO 3 AM EST WEDNESDAY FOR LSZ263-
264.
LAKE MICHIGAN...NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...JLB
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1201 PM CST TUE DEC 20 2011
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
Relatively warm boundary layer temperatures and a marginal
temperatures aloft for ice crystals over nw MO is making it
difficult to generate much in the way of snow. Instead we are left
with a wintry mix...and a light mix at that. Calls around to local
law enforcement indicate no impacts from ongoing weather and with
air temperatures expected to remain status quo or even inch up a
degree or two any snow which falls will most likely accumulate
mainly on grassy areas. With that in mind and only minor snow/sleet
accumulations forecast have opted to drop the winter weather
advisory.
MJ
&&
.PREV DISCUSSION...
/346 AM CST Tue Dec 20 2011/
In the short term a classic panhandle low continues to accomplish
what it often does for this portion of the region, that is, sending
copious amount of moisture northward and creating a headache for
winter precipitation forecasts.
Early this morning, expansive dry slot is now rapidly lifting
northeast and across eastern Kansas and western Missouri. With
satellite imagery indicating the loss of ice crystals we`re also
slowly losing much of our precipitation across the region. However,
during the past 18 hours extensive northward moisture transport
resulting in PWAT values nearly 1" (or within the 99th percentile
for this time of the year) and efficient rain processes have
produced near record rainfall in the local area. The result of
nearly 1-1.5" of rain will be the flooding of several rivers in
central Missouri. Further north, a more problematic forecast
persists as a tight moisture gradient has formed over extreme
northern Missouri thanks to Canadian high pressure over the Dakotas
and strong dry air advection behind a departing northern stream
trough in the Western Great Lakes. 00z OAX/DVN soundings confirmed
the extent of this moisture disparity, which is resulting in a
overall lack of precipitation reaching the ground despite the
extensive areal coverage of radar echoes. Thus, snowfall totals have
been severely hampered over NE Kansas and NW Missouri with isolated
totals of a half inch in some locations.
For today, following much of the guidance from the suite of
mesoscale models which have a reasonable handle on the current
situation. The 00z NMM, 06z NAM, and RUC are the most reasonable
solutions at this time. As dry slot rotates through the area, precip
will continue to diminish through 15z, with lingering activity
mainly in the northern zones. Soundings continue to support a mix of
snow/sleet and perhaps rain in and along the Highway 36 corridor.
Given the absence of ice crystals would also be concerned for a bit
of freezing drizzle. By the middle to late morning hours, we should
also begin to see the expansive deformation zone in southwestern
Kansas begin to lift northeast towards the area. However, as the
upper low begins to eject eastward, support for heavy precipitation
will diminish as in tandem the favorable upper jet streak and rich
moisture feed both shift eastward. Feel model qpf may be a bit too
high given the lack of ice aloft, but soundings similar to these have
produced periods of light rain/drizzle/sleet or even snow showers
before, just usually very light in nature. The best chance for any
wintry precip will remain in the northwestern third of the CWA with
little accumulation. Further south would expect more drizzle or light
rain showers than anything. Will continue with the advisory for now
given potential for some development, but feel impacts may be much
lower than earlier thought.
Tonight, as mentioned in previous discussion, models continue to
hint at an area of low static stability most likely tied to an
individual vort lobe rotating around the upper low. Mesoscale model
output remains consistent in bringing a pocket of strong omega,
non-coincident with the aforementioned deformation zone, through
southern Kansas and into portions of central Missouri. Soundings and
cross sections through this layer suggest that with rather high
freezing levels, would expect mainly a patch of light to moderate
rain showers. Would also not be surprised to see a rumble or two
of thunder, but confidence not high enough to include. It is
theoretically possible that there could be enough dynamical cooling
within this locally intensifying vort lobe to produce a very quick
batch of heavy snow. Once again, not a certain forecast at all. Of
more concern is the potential that if roads and paved surfaces cannot
dry out by nighttime as colder air arrives, a period of black ice may
be possible heading into Wednesday morning.
Wednesday: The region will quickly transition to a zonal or
southwest flow pattern aloft for Wednesday as energy again digs into
the southwestern United States. Given the lack of snowcover except
in the NW CWA and modest southwest low level flow have bumped up
high temperatures a category or two in most locations.
For Thursday: Secondary upper trough emanating out of the Southwest
will quickly race into the region on Thursday. The southerly track
of this wave will hold moisture well south of the CWA with a weak
surface ridge axis bisecting the area.
31
Thursday through Tuesday...
Models have been trending toward a slightly stronger system for
Thursday night and Friday. However, there is still some difficulty
with respect to interactions between the Northern Plains shortwave
trough. Regardless, since moisture is limited will keep the threat
of snow in the low chance category. Otherwise, for the rest of the
period, it will remain rather quiet with only weak shortwaves in
basically dry northwest upper flow.
DB
&&
.AVIATION...
For the 18Z TAFs, above freezing temperatures near the surface and a
lack of ice crystals aloft will result in intermittent drizzle into
the early evening with a period or tow of sleet mixed in between
KMCI and KSTJ. A weakening deformation zone with snow will move east
this evening into far western MO but a lack of cold air should
result in only a brief period or two of a rain/snow mix for
KMCI/KMKC while KSTJ stands a better chance of all snow. However,
only minor snow accumulations possible in KSTJ...half an inch or
less...and little if any accumulation for the KC terminals. Plenty
of residual low level moisture around indicates LIFR/IFR cigs even
after all of the precipitation moves east by midnight.
Winds will back to the southwest on Wednesday and the low stratus
will scatter out quickly by mid morning with VFR conditions.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
510 AM CST Tue Dec 20 2011
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
In the short term a classic panhandle low continues to accomplish
what it often does for this portion of the region, that is, sending
copious amount of moisture northward and creating a headache for
winter precipitation forecasts.
Early this morning, expansive dry slot is now rapidly lifting
northeast and across eastern Kansas and western Missouri. With
satellite imagery indicating the loss of ice crystals we`re also slowly
losing much of our precipitation across the region. However, during
the past 18 hours extensive northward moisture transport resulting in
PWAT values nearly 1" (or within the 99th percentile for this time of
the year) and efficient rain processes have produced near record
rainfall in the local area. The result of nearly 1-1.5" of rain will
be the flooding of several rivers in central Missouri. Further north,
a more problematic forecast persists as a tight moisture gradient has
formed over extreme northern Missouri thanks to Canadian high
pressure over the Dakotas and strong dry air advection behind a
departing northern stream trough in the Western Great Lakes. 00z
OAX/DVN soundings confirmed the extent of this moisture disparity,
which is resulting in a overall lack of precipitation reaching the
ground despite the extensive areal coverage of radar echoes. Thus,
snowfall totals have been severely hampered over NE Kansas and NW
Missouri with isolated totals of a half inch in some locations.
For today, following much of the guidance from the suite of
mesoscale models which have a reasonable handle on the current
situation. The 00z NMM, 06z NAM, and RUC are the most reasonable
solutions at this time. As dry slot rotates through the area, precip
will continue to diminish through 15z, with lingering activity
mainly in the northern zones. Soundings continue to support a mix of
snow/sleet and perhaps rain in and along the Highway 36 corridor.
Given the absence of ice crystals would also be concerned for a bit
of freezing drizzle. By the middle to late morning hours, we should
also begin to see the expansive deformation zone in southwestern
Kansas begin to lift northeast towards the area. However, as the
upper low begins to eject eastward, support for heavy precipitation
will diminish as in tandem the favorable upper jet streak and rich
moisture feed both shift eastward. Feel model qpf may be a bit too
high given the lack of ice aloft, but soundings similar to these have
produced periods of light rain/drizzle/sleet or even snow showers
before, just usually very light in nature. The best chance for any
wintry precip will remain in the northwestern third of the CWA with
little accumulation. Further south would expect more drizzle or light
rain showers than anything. Will continue with the advisory for now
given potential for some development, but feel impacts may be much
lower than earlier thought.
Tonight, as mentioned in previous discussion, models continue to
hint at an area of low static stability most likely tied to an
individual vort lobe rotating around the upper low. Mesoscale model
output remains consistent in bringing a pocket of strong omega,
non-coincident with the aforementioned deformation zone, through
southern Kansas and into portions of central Missouri. Soundings and
cross sections through this layer suggest that with rather high
freezing levels, would expect mainly a patch of light to moderate
rain showers. Would also not be surprised to see a rumble or two of
thunder, but confidence not high enough to include. It is
theoretically possible that there could be enough dynamical cooling
within this locally intensifying vort lobe to produce a very quick
batch of heavy snow. Once again, not a certain forecast at all. Of
more concern is the potential that if roads and paved surfaces cannot
dry out by nighttime as colder air arrives, a period of black ice may
be possible heading into Wednesday morning.
Wednesday: The region will quickly transition to a zonal or
southwest flow pattern aloft for Wednesday as energy again digs into
the southwestern United States. Given the lack of snowcover except
in the NW CWA and modest southwest low level flow have bumped up
high temperatures a category or two in most locations.
For Thursday: Secondary upper trough emanating out of the Southwest
will quickly race into the region on Thursday. The southerly track
of this wave will hold moisture well south of the CWA with a weak
surface ridge axis bisecting the area.
31
Thursday through Tuesday...
Models have been trending toward a slightly stronger system for
Thursday night and Friday. However, there is still some difficulty
with respect to interactions between the Northern Plains shortwave
trough. Regardless, since moisture is limited will keep the threat
of snow in the low chance category. Otherwise, for the rest of the
period, it will remain rather quiet with only weak shortwaves in
basically dry northwest upper flow.
DB
&&
.AVIATION...
For the 12Z tafs, much of the precipitation associated with the
strong isentropic lift has shifted east this morning. However, weak isentropic
lift ahead of the upper level storm system in Oklahoma will continue
to produce drizzle and patches of light rain. This will aid in
keeping ceilings in the LIFR category with MVFR visibilities today.
Little change is expected tonight as the upper level storm system
produces patches of light rain and snow. Any accumulation of snow is
expected to be below an inch.
DB
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY until 6 PM CST this evening FOR
MOZ001>005-011>014-020>022.
KS...WINTER WEATHER ADVISORY until 6 PM CST this evening FOR KSZ025-
102.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
346 AM CST Tue Dec 20 2011
.DISCUSSION...
In the short term a classic panhandle low continues to accomplish
what it often does for this portion of the region, that is, sending
copious amount of moisture northward and creating a headache for
winter precipitation forecasts.
Early this morning, expansive dry slot is now rapidly lifting
northeast and across eastern Kansas and western Missouri. With
satellite imagery indicating the loss of ice crystals we`re also slowly
losing much of our precipitation across the region. However, during
the past 18 hours extensive northward moisture transport resulting in
PWAT values nearly 1" (or within the 99th percentile for this time of
the year) and efficient rain processes have produced near record
rainfall in the local area. The result of nearly 1-1.5" of rain will
be the flooding of several rivers in central Missouri. Further north,
a more problematic forecast persists as a tight moisture gradient has
formed over extreme northern Missouri thanks to Canadian high
pressure over the Dakotas and strong dry air advection behind a
departing northern stream trough in the Western Great Lakes. 00z
OAX/DVN soundings confirmed the extent of this moisture disparity,
which is resulting in a overall lack of precipitation reaching the
ground despite the extensive areal coverage of radar echoes. Thus,
snowfall totals have been severely hampered over NE Kansas and NW
Missouri with isolated totals of a half inch in some locations.
For today, following much of the guidance from the suite of
mesoscale models which have a reasonable handle on the current
situation. The 00z NMM, 06z NAM, and RUC are the most reasonable
solutions at this time. As dry slot rotates through the area, precip
will continue to diminish through 15z, with lingering activity
mainly in the northern zones. Soundings continue to support a mix of
snow/sleet and perhaps rain in and along the Highway 36 corridor.
Given the absence of ice crystals would also be concerned for a bit
of freezing drizzle. By the middle to late morning hours, we should
also begin to see the expansive deformation zone in southwestern
Kansas begin to lift northeast towards the area. However, as the
upper low begins to eject eastward, support for heavy precipitation
will diminish as in tandem the favorable upper jet streak and rich
moisture feed both shift eastward. Feel model qpf may be a bit too
high given the lack of ice aloft, but soundings similar to these have
produced periods of light rain/drizzle/sleet or even snow showers
before, just usually very light in nature. The best chance for any
wintry precip will remain in the northwestern third of the CWA with
little accumulation. Further south would expect more drizzle or light
rain showers than anything. Will continue with the advisory for now
given potential for some development, but feel impacts may be much
lower than earlier thought.
Tonight, as mentioned in previous discussion, models continue to
hint at an area of low static stability most likely tied to an
individual vort lobe rotating around the upper low. Mesoscale model
output remains consistent in bringing a pocket of strong omega,
non-coincident with the aforementioned deformation zone, through
southern Kansas and into portions of central Missouri. Soundings and
cross sections through this layer suggest that with rather high
freezing levels, would expect mainly a patch of light to moderate
rain showers. Would also not be surprised to see a rumble or two of
thunder, but confidence not high enough to include. It is
theoretically possible that there could be enough dynamical cooling
within this locally intensifying vort lobe to produce a very quick
batch of heavy snow. Once again, not a certain forecast at all. Of
more concern is the potential that if roads and paved surfaces cannot
dry out by nighttime as colder air arrives, a period of black ice may
be possible heading into Wednesday morning.
Wednesday: The region will quickly transition to a zonal or
southwest flow pattern aloft for Wednesday as energy again digs into
the southwestern United States. Given the lack of snowcover except
in the NW CWA and modest southwest low level flow have bumped up
high temperatures a category or two in most locations.
For Thursday: Secondary upper trough emanating out of the Southwest
will quickly race into the region on Thursday. The southerly track
of this wave will hold moisture well south of the CWA with a weak
surface ridge axis bisecting the area.
31
Thursday through Tuesday...
Models have been trending toward a slightly stronger system for
Thursday night and Friday. However, there is still some difficulty
with respect to interactions between the Northern Plains shortwave
trough. Regardless, since moisture is limited will keep the threat
of snow in the low chance category. Otherwise, for the rest of the
period, it will remain rather quiet with only weak shortwaves in
basically dry northwest upper flow.
DB
&&
.AVIATION...
Initial wave of precipitation has shifted east of the terminals this
evening. Secondary, more scattered precip now beginning to shift
northward and should affect the terminals over the next several
hours. The anticipated dry slot now moving into southern Kansas and
will continue to progress northward, reaching the taf site during the
overnight hours. Prior to this, periodic rain and drizzle along with
IFR ceilings (perhaps occasionally LIFR within the heavier rain bands)
will overspread the Kansas City terminals. More uncertainty at KSTJ
where the temperature profile is hovering near the freezing mark.
Expect a rain and periodic snow mix within the heavier precipitation
areas to move across the taf site. Aforementioned dry slot should
overspread the terminals by ~09z, depleting any ice crystal growth
from the mid levels of the column. This is expected to result in a
transition to drizzle and freezing drizzle (depending on the surface
temperature at the respective terminals) through the afternoon hours.
There is a chance for a quick burst of light snow by the evening
hours tomorrow along the backside of the upper low. However,
confidence on the location and temperature profile precludes a
mention at this time.
Deroche
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY until 6 PM CST this evening FOR
MOZ001>005-011>014-020>022.
KS...WINTER WEATHER ADVISORY until 6 PM CST this evening FOR KSZ025-
102.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1107 PM CST MON DEC 19 2011
.UPDATE...
/935 PM CST MON DEC 19 2011/
MADE SOME MINOR TWEEKS TO THE FORECAST FOR TONIGHT AND EARLY TUESDAY
MORNING...NAMELY TO TRIM BACK THE MENTION OF WINTRY PRECIPITATION
ACROSS NORTHERN PORTIONS OF THE CWA. THE LATEST UPPER AIR DATA AND
SURFACE OBS SHOW DEEPER COLD AIR TO SUPPORT A POTENTIAL WINTRY MIX
IS BETTER JUXTAPOSED WEST OF THE CWA. THE LATEST MODEL GUIDANCE
INCLUDING THE RUC AND HRRR SUPPORT THIS AS WELL WITH GREATER CAA
WEST OF THE CWA. IN FACT A MULTITUDE OF SOUNDINGS SHOW VERY LOW
POTENTIAL FOR ANY SNOW OR SLEET THRU 12Z. AS A RESULT I HAVE
TRIMMED BACK THE MENTION OF RAIN...SLEET...SNOW TO KNOX AND LEWIS
COUNTIES FOR LATE TONIGHT...AFTER 09Z. AFTER THIS TIME I CAN`T
RULE OUT THE POSSIBILITY BUT EVEN IN THESE FEW COUNTIES IT MAY BE
TOO WARM.
GLASS
&&
.DISCUSSION...
/358 PM CST MON DEC 19 2011/
PRIMARY CONCERN WITH THIS FCST PCKG IS PRECIP CHANCES AND PTYPE FOR
THE NEXT 7 DAYS.
ISENTROPIC ASCENT AHEAD OF A LOW PRESSURE SYSTEM LIFTING NEWD INTO
THE SRN PLAINS WAS PRODUCING A BROAD PCPN SHIELD THIS AFTN THAT
STRETCHED ACROSS MOST OF KS AND MO AND INTO THE SRN HALF OF IL.
AMPLE MOISTURE WILL BE AVAILABLE FOR PCPN WITH MODELS SHOWING A
STRONG LLJ TRANSPORTING A VERY MOIST AIR MASS /PWAT VALUES OF
AROUND 1 INCH WHICH IS 2 STANDARD DEVIATIONS ABOVE NORMAL FOR
DECEMBER IN THIS PART OF THE COUNTRY/ NWD INTO THE REGION. PCPN
SHOULD CONTINUE OVERNIGHT AND INCREASE IN COVERAGE AS THE UPPER
LOW APPROACHES AND LARGE SCALE LIFT INCREASES WITH SOME ADDITIONAL
ENHANCEMENT PROVIDED BY WEAK JET COUPLING. TEMPERATURE PROFILES
CONTINUE TO SUPPORT AN ALL-RAIN EVENT ACROSS ALL BUT THE FAR NRN
CWA WHERE A COLD FRONT WAS EDGING SWD OUT OF IA. THE FAR NRN CWA
WILL BE VERY CLOSE TO THE TRANSITION ZONE BETWEEN RAIN AND SNOW
AND BUFKIT PROFILES AS WELL AS PARTIAL THICKNESS METHODS SUGGEST
THAT SNOW AND SLEET MAY MIX WITH THE RAIN AT TIMES. AS THE SFC LOW
LIFTS OUT OF THE TX PANHANDLE TONIGHT AND TOMORROW...THE BOUNDARY
WILL BE LIFTED NWD AS A WARM FRONT AND PCPN SHOULD CHANGE BACK TO
RAIN. DRY SLOT EFFECTS MAY CAUSE PCPN TO FALL MORE AS DRIZZLE THAN
AS RAIN FOR THE SRN HALF OF THE CWA TOMORROW AND TOMORROW NIGHT.
FINALLY...COLD AIR WRAPPING AROUND THE BACK SIDE OF THE DEPARTING
SYSTEM MAY CAUSE SNOW TO MIX WITH RAIN ACROSS NWRN PARTS OF THE
CWA TOMORROW NIGHT. ATTM IT APPEARS THAT THE DEFORMATION ZONE WILL
REMAIN NORTH AND WEST OF THE CWA. BARRING ANY UNEXPECTED SHIFTS IN
THE TRACK OF THIS SYSTEM...LESS THAN A HALF INCH OF SNOW AND SLEET
ACCUMULATION IS EXPECTED ACROSS THE FAR NRN CWA.
MEANWHILE...WATER VAPOR IMAGERY SHOWED ANOTHER SHORTWAVE DROPPING
SWD ALONG THE CA COAST TOWARDS BAJA CALIFORNIA. MODELS ARE IN GOOD
AGREEMENT THAT THIS SYSTEM CLOSES OFF AND SLOWS DOWN BEFORE MOVING
THROUGH NRN MEXICO AND FINALLY LIFTING THROUGH ERN TX ON WED/THU IN
RESPONSE TO THE STRONGER SHORTWAVE REACHING THE WA/OR COAST ON TUE
NIGHT. THE SHORTWAVE CURRENTLY ALONG THE CA COAST IS NOT EXPECTED TO
PRODUCE ANY PCPN FOR OUR AREA AS IT LIFTS THROUGH THE SRN CONUS.
HOWEVER...MODELS SHOW THAT THE OTHER SYSTEM DEEPENS AFTER CROSSING
THE ROCKIES AND TAKES A TRACK THAT WOULD BE FAVORABLE FOR SNOWFALL
ACROSS MOST OF THE CWA. THERE ARE STILL SIGNIFICANT DIFFERENCES
BETWEEN THE GFS/ECMWF/GEM /ESPECIALLY WRT PHASING WITH NRN STREAM
SHORTWAVES/ AND BETTER MODEL AGREEMENT MIGHT NOT OCCUR UNTIL AFTER
THESE FEATURES HAVE BEEN SAMPLED BY THE UPPER AIR NETWORK.
KANOFSKY
&&
.AVIATION...
/1104 PM CST MON DEC 19 2011/
NOT MUCH CHANGED FOR THIS TAF SET. CURRENT CONDITIONS ARE EXPECTED
TO IMPROVE TUES AFTERNOON FOR A SHORT PERIOD BEFORE DROPPING BACK
INTO IFR RANGE. LATEST GUIDANCE CONTINUES TO SUGGEST PRECIP WILL
FALL AS RA THRU THE TAF PERIOD. HOWEVER...TEMPS ARE EXPECTED TO
DROP TO NEAR FREEZING AT UIN.
SPECIFICS FOR KSTL...NOT MUCH CHANGED FOR THIS TAF SET. CURRENT
CONDITIONS ARE EXPECTED TO IMPROVE TUES AFTERNOON FOR A SHORT
PERIOD BEFORE DROPPING BACK INTO IFR RANGE. LATEST GUIDANCE
CONTINUES TO SUGGEST PRECIP WILL FALL AS RA THRU THE TAF PERIOD.
TILLY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1052 PM CST MON DEC 19 2011
.AVIATION...06Z KGRI. A MID-LEVEL DECK OF CLOUDS SHOULD HANG
AROUND FOR MOST OF THE FORECAST AND THEN GIVE WAY TO HIGHER LEVEL
CLOUDINESS BY TUESDAY AFTERNOON. WIND WILL GRADUALLY DECREASE WITH
TIME AND BY LATE TUESDAY AFTERNOON...BECOME LIGHT MAINLY FROM THE
SOUTHWEST.
&&
PREV DISCUSSION... /ISSUED 349 PM CST MON DEC 19 2011/
SHORT TERM...MORNING UPPER AIR ANALYSIS AND WATER VAPOR IMAGERY
INDICATE A MID AND UPPER LEVEL LOW OVER WEST TEXAS...MOVING NORTHEAST
INTO THE CENTRAL CONUS. WATER VAPOR IMAGERY ALSO INDICATES A MID
LEVEL DRY INTRUSION MOVING NORTHEASTWARD INTO NORTHERN TEXAS AND
PORTIONS OF OKLAHOMA. AT THE SURFACE AN AREA OF LOW PRESSURE EXISTS OVER
THE PANHANDLE OF TEXAS AND A SURFACE FRONT EXTENDS NORTHEAST FROM
THE SURFACE LOW INTO WESTERN AND NORTHERN OKLAHOMA...AS WELL AS
EASTERN KANSAS. KUEX INDICATES INCOMING PRECIPITATION OVER NORTH
CENTRAL KANSAS IN A ZONE OF LOW LEVEL THERMAL ADVECTION AND
RESULTANT ISENTROPIC UPGLIDE AND SATURATION. ADDITIONAL FORCING
THROUGH A ZONE OF MID LEVEL DIFFLUENCE IS ALSO HELPING PROMOTE
PRECIPITATION OVER AREAS NORTHEAST OF THE MID LEVEL LOW. SNOW IS
ALREADY IN PROGRESS AT NATOMA AS A RESULT.
THE LOW LEVEL BAROCLINIC ZONE CLEARED OUR CWA EARLIER TODAY AND
THE LOW LEVEL WIND FIELD ACROSS OUR CWA REMAINS FROM THE
NORTH/NORTHEAST AS A RESULT. SURFACE TEMPERATURES HAVE BEEN AT A
NEAR STANDSTILL IF NOT FALLING SOMEWHAT TODAY...WITH TEMPERATURES
AS OF MID AFTERNOON GENERALLY IN THE LOWER 30S. SHORT TERM GUIDANCE
CONTINUES TO SUGGEST THE MID LEVEL LOW WILL MOVE NORTHEAST ACROSS
THE SOUTHERN AND CENTRAL PLAINS TONIGHT AND TUESDAY. LOW LEVEL
THERMAL ADVECTION...WORKING IN CONCERT WITH MID LEVEL DIFFLUENCE AND
DEFORMATION TO THE NORTH AND NORTHEAST OF THE MID LEVEL LOW...WILL CONTINUE
PROMOTING PRECIPITATION PRODUCTION OVER THE AREA TONIGHT.
PRECIPITATION IS ALSO EXPECTED DURING THE DAY TUESDAY AS MID LEVEL
DEFORMATION TO THE NORTH AND NORTHWEST OF THE MID LEVEL LOW CLEARS
THE AREA.
MOISTURE THROUGH THE LOWER HALF OF THE TROPOSPHERIC COLUMN IS
EXPECTED TO REMAIN QUITE HIGH THROUGH THE NEXT 24 HOURS WITH 500MB
DEW POINTS IN EXCESS OF -25 DEGREES C AND 700MB DEW POINTS IN
EXCESS OF -10 DEGREES C ACROSS OUR SOUTH/SOUTHEAST. THESE MOISTURE
LEVELS...WORKING IN CONCERT WITH THE AFOREMENTIONED KINEMATIC
FORCING...SHOULD BE MORE THAN SUFFICIENT FOR SIGNIFICANT
PRECIPITATION PRODUCTION ACROSS OUR SOUTH AND SOUTHEAST TONIGHT AND
TOMORROW. QPF FIELDS FROM THE NAM...OPERATIONAL GFS...EC AND SREF-
MEAN ALL SUGGEST STORM TOTAL LIQUID PRECIPITATION AMOUNTS IN
EXCESS OF 0.80" ACROSS OUR SOUTH AND SOUTHEAST. SURFACE
TEMPERATURES WILL LIKELY FALL INTO THE UPPER AND MID 20S THROUGH
THE REMAINDER OF THE EVENT AND AS A RESULT WILL GO AHEAD AND
ASSUME A 10:1 SNOW-WATER RATIO TO START THE EVENT...WITH RATIOS
CLIMBING TO NEAR 13:1 BY TONIGHT AND TOMORROW. THIS YIELDS STORM
TOTAL SNOWFALL ACCUMULATIONS ON THE ORDER OF 5-12 INCHES ACROSS
OUR EXTREME SOUTH...AND STORM TOTAL SNOWFALL ACCUMULATIONS IN THE
1-5 INCH RANGE FARTHER NORTH.
LOW LEVEL PRESSURE RISES POST-FROPA HAVE PROMOTED AN INCREASED LOW
LEVEL PRESSURE GRADIENT TODAY...WITH SUSTAINED WINDS NEAR 20KTS
ACROSS MUCH OF THE CWA AS OF MID AFTERNOON. THESE CONDITIONS ARE EXPECTED
TO CONTINUE THROUGH THIS EVENING...WITH DIMINISHING WINDS EXPECTED
BY MIDNIGHT AS THE LOW LEVEL PRESSURE GRADIENT RELAXES. AS A
RESULT...THESE WINDS SHOULD REMAIN WELL BELOW BLIZZARD CRITERIA.
ALL THAT BEING SAID...THE INHERITED WINTER STORM WARNING FOR
ROOKS...OSBORNE AND MITCHELL COUNTIES...ALONG WITH THE WINTER
WEATHER ADVISORY FOR PHILLIPS...SMITH AND JEWELL COUNTIES...APPEAR
TO BE RIGHT ON...BUT DID GO AHEAD AND START THE WINTER STORM
WARNING NOW GIVEN SNOWFALL IS ALREADY OCCURRING AT NATOMA.
JUST A FEW THINGS TO CONSIDER AS WE HEAD INTO THIS STORM. THE
CONTRAST BETWEEN MOIST AIR AND DRY AIR...AS WELL AS BETWEEN STRONG
KINEMATIC FORCING AND NEXT TO NO FORCING...IS EXPECTED TO BE RATHER
SHARP THUS RESULTING IN A VERY TIGHT GRADIENT OF STORM TOTAL
SNOWFALL ACCUMULATIONS. ALTHOUGH CONFIDENCE REMAINS HIGH REGARDING
ACTUAL STORM TOTAL SNOWFALL ACCUMULATIONS...THE AXIS OF HEAVIEST
SNOW COULD SHIFT DRAMATICALLY IN RESPONSE TO VERY SMALL DEVIATIONS
IN STORM PATH. THANKFULLY...GUIDANCE HAS REMAINED FAIRLY
CONSISTENT WITH RESPECT TO STORM PATH...A TREND WHICH WE HOPE WILL
CONTINUE. FINALLY...GUIDANCE DOES SUGGEST THE MID LEVEL DRY
INTRUSION WILL INFILTRATE MUCH OF KANSAS BY TUESDAY MORNING...THUS
DRYING OUT THE DENDRITIC LAYER AND LIKELY LEADING TO A PERIOD OF
FREEZING DRIZZLE. AT THIS TIME IT APPEARS THIS MID LEVEL DRY
INTRUSION SHOULD REMAIN SOUTH AND SOUTHEAST OF OUR AREA AND AS A
RESULT...LEFT ANY MENTION OF FREEZING DRIZZLE OUT OF THE FORECAST.
LONG TERM...TUESDAY NIGHT THROUGH MONDAY. THE UPPER LOW WILL
CONTINUE TO MOVE NORTHEAST AND AWAY FROM THE AREA TUESDAY NIGHT.
THE MAJORITY OF MODEL SOLUTIONS SUGGESTS THE SNOW SHOULD BE DONE BY
TUESDAY NIGHT...AND WILL CONTINUE TO CARRY A DRY FORECAST.
A BRIEF H5 RIDGE BUILDS IN TUESDAY NIGHT INTO WEDNESDAY...WHICH
SHOULD KEEP IT DRY THROUGH WEDNESDAY...HOWEVER ANOTHER UPPER
TROUGH/LOW BEGINS TO APPROACH THE REGION WEDNESDAY NIGHT. THE
NAM/GFS/ECMWF ALL AGREE THAT MOST OF WEDNESDAY EVENING SHOULD REMAIN
DRY...HOWEVER LIGHT SNOW COULD BEGIN TO APPROACH FAR NORTH AND WEST
PORTIONS OF THE FORECAST AREA BY LATE EVENING. THE SNOW CHANCES
WILL THEN SPREAD ACROSS THE FORECAST AREA OVERNIGHT WEDNESDAY INTO
THURSDAY. THE NAM/GFS DEPICT THE STRONGEST LIFT/FORCING ACROSS
ROUGHLY THE SOUTHERN HALF OF THE CWA LATE WEDNESDAY NIGHT INTO
THURSDAY...AND HAVE INCREASED POPS FOR THAT AREA...ESPECIALLY FOR
THURSDAY. SNOW AMOUNTS ARE STILL UNCERTAIN...AND SREF 12 HOUR SNOW
PROBABILITIES FOR AN INCH OR MORE OF SNOW ARE NOT VERY HIGH...THOUGH
THE HIGHER PROBABILITIES ARE SHOWN IN THE SOUTH AND WEST.
ONE CONCERN IS THE POTENTIAL FOR HIGHER SNOW RATIOS WITH THE CARIBOU
SNOW TECHNIQUE SUGGESTING RATIOS CLIMBING TO NEAR 18 TO 1 FOR
THURSDAY AFTERNOON. FOR NOW...WILL GO WITH A GENERAL HALF INCH TO
INCH AND A HALF...WITH THE HIGHER AMOUNTS IN THE SOUTH AND WEST.
THERE IS STILL PLENTY OF TIME TO REFINE AMOUNTS AS THIS NEXT SYSTEM
GETS CLOSER.
OVERALL...THE CHRISTMAS HOLIDAY WEEKEND LOOKS TO BE FAIRLY QUIET.
ANOTHER WAVE COULD MOVE ACROSS THE REGION SATURDAY NIGHT INTO
CHRISTMAS DAY...BUT MOISTURE IS LACKING SO IT SHOULD PASS THROUGH
DRY. TEMPERATURES ARE EXPECTED TO BE FAIRLY SEASONABLE WITH HIGHS
PRIMARILY IN THE 30S.
PREV DISCUSSION... /ISSUED 1120 AM CST MON DEC 19 2011/
AVIATION...18Z TAF. IFR CEILINGS HAVE MOVED INTO PARTS OF SOUTH
CENTRAL NEBRASKA BEHIND A COLD FRONT THAT TRAVELED ACROSS THE
AREA EARLIER TODAY. THE GENERAL TREND HAS BEEN FOR THE IFR
CEILINGS TO LIFT TO MVFR...AND THIS IS ALSO SHOWN BY THE LATEST
NAM PROXIMITY SOUNDINGS..SO WILL ONLY CARRY THE LOWER CEILINGS IN
A BRIEF TEMPO GROUP. PROXIMITY SOUNDINGS ALSO SHOW THE MVFR
CEILINGS IMPROVING THIS AFTERNOON...THOUGH THE RUC IS FASTER IN
LIFTING THE CEILINGS THAN THE NAM. WILL AIM FOR MORE OF A
COMPROMISE SOLUTION AND GO WITH 21Z AS A START. WINDS WILL REMAIN
GUSTY AND FROM THE NORTH MOST OF THE AFTERNOON...BUT THEY SHOULD
DIMINISH THIS EVENING. THERE WILL BE CHANCES OF SNOW SOUTH OF
KGRI AS A STORM SYSTEM MOVES ACROSS THE CENTRAL AND SOUTHERN
PLAINS...BUT THINK THAT THE CHANCES WILL STAY FAR ENOUGH SOUTH TO
KEEP THE MENTION OUT OF THE FORECAST AT KGRI.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR KSZ005>007.
WINTER STORM WARNING UNTIL 6 PM CST TUESDAY FOR KSZ017>019.
&&
$$
SHORT TERM...BRYANT
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
649 AM EST TUE DEC 20 2011
.SYNOPSIS...
HIGH PRESSURE LOCATED OVER THE GREAT LAKES WILL MOVE TOWARD THE
NORTH COUNTRY TODAY. THIS WILL PROVIDE OUR REGION WITH INCREASING
AMOUNTS OF SUNSHINE...ALONG WITH COOL NORTHERLY WINDS. TEMPERATURES
WILL HOLD IN THE UPPER TEENS IN THE MOUNTAINS TO THE MID TO UPPER
20S IN THE VALLEYS. THE NEXT STORM SYSTEM WILL IMPACT THE REGION
WEDNESDAY INTO THURSDAY...WITH MIXED PRECIPITATION QUICKLY
CHANGING TO A COLD RAIN. TEMPERATURES WILL WARM BACK INTO THE 30S
TO NEAR 40 IN MANY LOCATIONS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 600 AM EST TUESDAY...SEVERAL CHANGES TO CRNT FCST BASED ON IR
SATL PICS AND LATEST TEMPS. SFC COLD FRNT HAS PUSHED INTO SOUTHERN
NEW ENGLAND THIS MORNING WHILE LLVL CAA CONTS. THIS HAS RESULTED
IN A TIGHT NORTH TO SOUTH THERMAL GRADIENT ACRS OUR CWA...ALONG
WITH A WIDE RANGE IN TEMPS. TEMPS RANGE FROM THE M/U TEENS ACRS
NNY TO 35F AT VSF. WL UPDATE WITH CRNT TEMPS ATTM AND INCREASE
DAYTIME HIGHS BY SEVERAL DEGREES ACRS CENTRAL/SOUTHERN VT. IN
ADDITION...LATEST RUC13 SHOWS PLENTY OF LLVL MOISTURE RESULTING IN
LOTS OF CLOUDS ACRS OUR CWA. HAVE INCREASED CLOUDS ACRS MOST OF
THE REGION...BUT EXPECT AREAL COVERAGE TO DECREASE BY 15Z TODAY.
REST OF FCST IN GOOD SHAPE.
WATER VAPOR SHOWS WELL DEFINED SHORT WAVE QUICKLY MOVING
SOUTHEAST OF OUR CWA THIS MORNING ASSOCIATED WITH SFC COLD
FRNT...WHILE AREA OF SUBSIDENCE/DRY AIR ALOFT ADVECTS INTO OUR
REGION. THIS COMBINED WITH SFC HIGH PRES OVERHEAD BY 18Z
TODAY...WL RESULT IN CLRING SKIES AND PLENTY OF SUNSHINE. THE
COMBINATION OF LEFTOVER MOISTURE AND SOME WEAK UPSLOPE FLW THIS
MORNING MAY PRODUCE A FEW FLURRIES AND CLOUDS ACRS THE MTNS. TEMPS
WL BE TRICKY WITH SHARP THERMAL GRADIENT AND ASSOCIATED CAA ACRS
OUR CWA TODAY. THINKING U10S MTNS/SLK TO NEAR L30S VSF...WITH MANY
AREAS HOLDING IN THE M/U 20S.
TONIGHT...SFC HIGH PRES QUICKLY SHIFTS OFF THE MID ATLANTIC COAST
WITH A RETURN SOUTHERLY FLW DEVELOPING. THIS RESULTS IN SIGNIFICANT
WARMING OF THE LLVLS WITH 850MB TEMPS NEAR 0C BY 12Z WEDS ACRS OUR
SOUTHERN ZNS. THE COMBINATION OF WAA...INCREASING CLOUDS...AND
DEVELOPING SOUTHERLY FLW WL MAKE FOR A CHALLENGING LOW TEMP FCST.
THINKING COLDEST TEMPS WL BE ACRS THE NEK/EASTERN VT WITH LOWS IN
THE LOWER TEENS TO NEAR 20F CPV/SLV. ONCE AGAIN EXPECT LOWS TO BE
BEFORE MIDNIGHT WITH TEMPS RISING TWD MORNING. WL CONT TO MENTION
SCHC/CHC POPS ALONG AND SOUTH OF A MSS TO SLK TO MPV LINE BTWN
09Z-12Z WEDS...ASSOCIATED WITH WAA LIFT/MOISTURE. OVERALL QPF
AMOUNTS WL BE VERY LIGHT...WITH MOST OF THE PRECIP EVAPORATING
BEFORE REACHING THE GROUND...DUE TO VERY DEEP DRY AIR AHEAD OF
MOISTURE/LIFT. THERMAL PROFILES SUPPORT ALL SNOW THRU 12Z
WEDS...WITH ONLY A DUSTING OF ACCUMULATIONS ANTICIPATED.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 415 AM EST TUESDAY...FCST FOCUS WL BE PRECIP EVENT WEDS
INTO THURS...ASSOCIATED WITH SOUTHERN PLAINS SYSTEM. ONCE AGAIN A
MAINLY COLD RAIN EVENT IS ANTICIPATED WITH QPF AMOUNTS BTWN 0.10
FOR THE CPV TO 0.40" FOR THE DACKS AND PARTS OF THE SOUTHERN GREEN
MTNS. SEVERAL PERIODS OF MAINLY LIGHT RAIN IS ANTICIPATED...WITH
BEST DEEP LAYER LIFT/MOISTURE BEING ACRS CENTRAL/SOUTHERN VT.
FIRST SURGE OF 850 TO 500MB MOISTURE AND 700 TO 500MB LIFT WL MOVE
FROM SOUTHWEST TO NORTHEAST ACRS OUR CWA BTWN 12Z-15Z WEDS.
THERMAL PROFILES SUPPORT A MIX OF SNOW...SLEET...AND FREEZING
RAIN...ESPECIALLY EAST OF THE GREEN MTNS...BUT TOTAL QPF AMOUNTS
ASSOCIATED WITH INITIAL BAND OF PRECIP WL BE LIGHT AND ONLY A
DUSTING OF SNOW/SLEET IS ANTICIPATED. LOW LEVEL SOUTH TO SOUTHWEST
FLW WL QUICKLY ADVECT WARMER TEMPS ACRS OUR CWA BY 15Z WEDS...WITH
85H TEMPS RISING BTWN +3C AND +5C...AND 925MB TEMPS NEAR +3C. IN
ADDITION...GIVEN POSITION OF SFC HIGH PRES WITH NO BLOCKING
SIGNATURE IN THE SLP FIELDS...FEEL COLD AIR WL QUICKLY RETREAT.
ALSO...LIMITED SNOW PACK AND DEVELOPING SOUTHERLY FLW WL HELP TO
ERODE LLVL COLD AIR...BEFORE HEAVIER PRECIP ARRIVES AFT 18Z WEDS.
THE BETTER DYNAMICS ASSOCIATED WITH DECAYING MID/UPPER LVL
CIRCULATION AND POTENT 5H VORT MOVES ACRS OUR CWA BTWN 21Z-06Z.
THIS ULVL SUPPORT COMBINED WITH GOOD 850 TO 500MB Q-VECTOR
CONVERGENCE AND GOOD AVAILABLE MOISTURE WITH PWS APPROACHING
0.75"...WL RESULT IN A PERIOD OF OCCASIONAL LIGHT RAIN ACRS OUR
CWA ON WEDS NIGHT. ONCE AGAIN...A FEW POCKETS OF FREEZING RAIN WL
BE POSSIBLE ACRS EASTERN VT/NEK...BUT NOT ANTICIPATING ANY ICE
ACCUMULATION ATTM. TEMPS WL WARM INTO THE L40S CPV TO M30S
NEK/EASTERN VT ON WEDS. LITTLE CHANGE IN TEMPS IS EXPECTED ON WEDS
NIGHT WITH CLOUDS AND PRECIP EXPECTED. SFC COLD FRNT APPROACHES
NORTHERN CWA BY 12Z THURS...WITH TIGHT THERMAL GRADIENT. THIS WL
PUSH ACRS OUR FA ON THURS...WITH COOLER TEMPS AND THE CHANCE FOR
RAIN/SNOW SHOWERS. UNFORTUNATELY...AS THE AIR BECMS COLD ENOUGH TO
SUPPORT SNOW...THE BEST MOISTURE MOVES TO OUR EAST. NOT
ANTICIPATING MUCH SNOW ACCUMULATION...MAYBE AN INCH OR SO IN THE
FAVORABLE UPSLOPE REGIONS OF THE DACKS/GREEN MTNS. TEMPS WL START
NEAR 40F IN THE CPV...BUT WL FALL INTO THE 30S AS NORTH WINDS AND
LLVL CAA DEVELOPS. OTHERWISE...MAINLY 30S WL BE THE HIGHS ON THURS
ACRS THE MTNS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 230 PM EST MONDAY...DEVELOPING COLD FRONT NORTH OF THE
INTERNATIONAL BORDER WILL DROP SOUTH INTO FORECAST LATER THURSDAY
NIGHT. MEANWHILE...LOW PRESSURE WILL TRACK SOUTH OF THE AREA PASSING
OFF MID ATLANTIC COAST. EXPECT SOME SNOW SHOWERS ASSOCIATED WITH
COLD FRONT TO AFFECT NORTHERN ZONES...WITH LIGHT SNOW ASSOCIATED
WITH LOW TO OUR SOUTH POSSIBLY AFFECTING SOUTHERN ZONES. ALL ADDS
UP TO CHANCE POPS...MAINLY AFTER MIDNIGHT. LOW DEPARTS OFFSHORE FRIDAY
MORNING...BUT THERE WILL BE A CONTINUED CHANCE FOR A FEW SNOW SHOWERS
AS THE COLD FRONT DEPRESSES SOUTH OF FORECAST AREA BY AFTERNOON.
HIGH PRESSURE BUILDING ACROSS ONTARIO INTO QUEBEC LATER FRIDAY
INTO SATURDAY WILL BRING MAINLY DRY WEATHER TO THE NORTH COUNTRY
ALONG WITH COLDER TEMPERATURES. LOWS FRIDAY NIGHT UNDER MAINLY CLEAR
SKIES WILL BE MAINLY IN THE TEENS...AND HIGHS ON SATURDAY IN THE
UPPER 20S TO LOWER 30S.
SITUATION BECOMES MORE COMPLICATED SATURDAY NIGHT AS HIGH MOVES
INTO EASTERN CANADA AND SHORTWAVE AND ASSOCIATED SURFACE LOW LIFT
NORTHEAST FROM THE TENNESSEE VALLEY. SOME RATHER SIGNIFICANT
DIFFERENCES BETWEEN GFS AND ECMWF REGARDING THIS SYSTEM...
ESPECIALLY WITH RESPECT TO TIMING. GFS MUCH FASTER...BRINGING
PRECIPITATION IN QUICKLY SATURDAY NIGHT AND EXITING CHRISTMAS
MORNING. TEMP PROFILE ON GFS WARMS ENOUGH SO THAT PTYPE MAY BECOME
AN ISSUE. ECMWF MAINTAINS DRY CONDITIONS SATURDAY NIGHT WITH BULK
OF PCPN SUNDAY PM/EVENING...AND MAINLY SNOW AS TEMPS SLIGHTLY
COOLER. HAVE ATTEMPTED TO BLEND THE TWO MODELS. LOW CONFIDENCE IN
TIMING OF THIS SYSTEM...BUT CONFIDENCE INCREASING THAT THERE WILL
BE AN EVENT IN THE SATURDAY NIGHT TO SUNDAY NIGHT TIMEFRAME. HAVE
GONE WITH 40 POPS FOR SNOW OR SNOW/RAIN MIX ACROSS THE AREA...SO
THERE IS HOPE FOR THOSE LOOKING FOR A WHITE CHRISTMAS. THOSE WITH
TRAVEL INTERESTS AROUND CHRISTMAS DAY SHOULD MONITOR LATEST
FORECASTS. DRIER CONDITIONS EXPECTED MONDAY...ALTHOUGH THERE MAY
BE A FEW SNOW SHOWERS...ESPECIALLY OVER NORTHERN SECTIONS.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
THROUGH 12Z WEDNESDAY...INTERMITTENT LIGHT SNOW SHOWERS OVER THE
GREEN MOUNTAINS INCLUDING KMPV WILL BE ENDING BY 14Z. AREAS OF
MVFR CIGS THIS MORNING WILL IMPROVE TO VFR AT ALL SITES BY
16Z...WITH MAINLY CLEAR SKIES EXPECTED THIS AFTERNOON/EVENING AS
HIGH PRESSURE MOVES ACROSS THE REGION. EXPECT AN INCREASE IN
CLOUDS TONIGHT WITH CHANCE LIGHT SNOW AND MVFR CONDITIONS TOWARDS
12Z WEDNESDAY. GUSTY NORTHWEST WINDS WILL DIMINISH THIS MORNING
AND BECOME LIGHT AND VARIABLE THIS AFTERNOON.
OUTLOOK 12Z WEDNESDAY THROUGH SATURDAY...
MVFR CEILINGS AND MIXED PCPN DEVELOPING EARLY WEDNESDAY WITH
APPROACHING WARM FRONT. LIGHT SNOW/SLEET MIX WILL CHANGE TO RAIN
BY WEDNESDAY AFTERNOON. MVFR WITH PERIODS OF IFR CEILINGS EXPECTED
MUCH OF WEDNESDAY AND WEDNESDAY NIGHT WITH HIR TRRN OBSCD.
THURSDAY WILL FEATURE PARTIAL CLEARING WITH SOME MVFR CEILINGS...
ESPECIALLY AT MPV/SLK. COLD FRONT BRINGS CHANCE SNOW SHOWERS WITH
POSSIBLE MVFR CONDITIONS FRIDAY MORNING. HIGH PRESSURE AND VFR
CONDITIONS EXPECTED FRIDAY PM/NIGHT AND CONTINUING THROUGH MUCH OF
SATURDAY. NEXT FRONTAL SYSTEM APPROACHES FROM THE SOUTHWEST LATE
SATURDAY WITH IFR SNOW POSSIBLE SATURDAY NIGHT.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...TABER
NEAR TERM...TABER
SHORT TERM...TABER
LONG TERM...RJS
AVIATION...RJS
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
600 AM EST TUE DEC 20 2011
.SYNOPSIS...
HIGH PRESSURE LOCATED OVER THE GREAT LAKES WILL MOVE TOWARD THE
NORTH COUNTRY TODAY. THIS WILL PROVIDE OUR REGION WITH INCREASING
AMOUNTS OF SUNSHINE...ALONG WITH COOL NORTHERLY WINDS. TEMPERATURES
WILL HOLD IN THE UPPER TEENS IN THE MOUNTAINS TO THE MID TO UPPER
20S IN THE VALLEYS. THE NEXT STORM SYSTEM WILL IMPACT THE REGION
WEDNESDAY INTO THURSDAY...WITH MIXED PRECIPITATION QUICKLY
CHANGING TO A COLD RAIN. TEMPERATURES WILL WARM BACK INTO THE 30S
TO NEAR 40 IN MANY LOCATIONS ON WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 600 AM EST TUESDAY...SEVERAL CHANGES TO CRNT FCST BASED ON IR
SATL PICS AND LATEST TEMPS. SFC COLD FRNT HAS PUSHED INTO SOUTHERN
NEW ENGLAND THIS MORNING WHILE LLVL CAA CONTS. THIS HAS RESULTED
IN A TIGHT NORTH TO SOUTH THERMAL GRADIENT ACRS OUR CWA...ALONG
WITH A WIDE RANGE IN TEMPS. TEMPS RANGE FROM THE M/U TEENS ACRS
NNY TO 35F AT VSF. WL UPDATE WITH CRNT TEMPS ATTM AND INCREASE
DAYTIME HIGHS BY SEVERAL DEGREES ACRS CENTRAL/SOUTHERN VT. IN
ADDITION...LATEST RUC13 SHOWS PLENTY OF LLVL MOISTURE RESULTING IN
LOTS OF CLOUDS ACRS OUR CWA. HAVE INCREASED CLOUDS ACRS MOST OF
THE REGION...BUT EXPECT AREAL COVERAGE TO DECREASE BY 15Z TODAY.
REST OF FCST IN GOOD SHAPE.
WATER VAPOR SHOWS WELL DEFINED SHORT WAVE QUICKLY MOVING
SOUTHEAST OF OUR CWA THIS MORNING ASSOCIATED WITH SFC COLD
FRNT...WHILE AREA OF SUBSIDENCE/DRY AIR ALOFT ADVECTS INTO OUR
REGION. THIS COMBINED WITH SFC HIGH PRES OVERHEAD BY 18Z
TODAY...WL RESULT IN CLRING SKIES AND PLENTY OF SUNSHINE. THE
COMBINATION OF LEFTOVER MOISTURE AND SOME WEAK UPSLOPE FLW THIS
MORNING MAY PRODUCE A FEW FLURRIES AND CLOUDS ACRS THE MTNS. TEMPS
WL BE TRICKY WITH SHARP THERMAL GRADIENT AND ASSOCIATED CAA ACRS
OUR CWA TODAY. THINKING U10S MTNS/SLK TO NEAR L30S VSF...WITH MANY
AREAS HOLDING IN THE M/U 20S.
TONIGHT...SFC HIGH PRES QUICKLY SHIFTS OFF THE MID ATLANTIC COAST
WITH A RETURN SOUTHERLY FLW DEVELOPING. THIS RESULTS IN SIGNIFICANT
WARMING OF THE LLVLS WITH 850MB TEMPS NEAR 0C BY 12Z WEDS ACRS OUR
SOUTHERN ZNS. THE COMBINATION OF WAA...INCREASING CLOUDS...AND
DEVELOPING SOUTHERLY FLW WL MAKE FOR A CHALLENGING LOW TEMP FCST.
THINKING COLDEST TEMPS WL BE ACRS THE NEK/EASTERN VT WITH LOWS IN
THE LOWER TEENS TO NEAR 20F CPV/SLV. ONCE AGAIN EXPECT LOWS TO BE
BEFORE MIDNIGHT WITH TEMPS RISING TWD MORNING. WL CONT TO MENTION
SCHC/CHC POPS ALONG AND SOUTH OF A MSS TO SLK TO MPV LINE BTWN
09Z-12Z WEDS...ASSOCIATED WITH WAA LIFT/MOISTURE. OVERALL QPF
AMOUNTS WL BE VERY LIGHT...WITH MOST OF THE PRECIP EVAPORATING
BEFORE REACHING THE GROUND...DUE TO VERY DEEP DRY AIR AHEAD OF
MOISTURE/LIFT. THERMAL PROFILES SUPPORT ALL SNOW THRU 12Z
WEDS...WITH ONLY A DUSTING OF ACCUMULATIONS ANTICIPATED.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 415 AM EST TUESDAY...FCST FOCUS WL BE PRECIP EVENT WEDS
INTO THURS...ASSOCIATED WITH SOUTHERN PLAINS SYSTEM. ONCE AGAIN A
MAINLY COLD RAIN EVENT IS ANTICIPATED WITH QPF AMOUNTS BTWN 0.10
FOR THE CPV TO 0.40" FOR THE DACKS AND PARTS OF THE SOUTHERN GREEN
MTNS. SEVERAL PERIODS OF MAINLY LIGHT RAIN IS ANTICIPATED...WITH
BEST DEEP LAYER LIFT/MOISTURE BEING ACRS CENTRAL/SOUTHERN VT.
FIRST SURGE OF 850 TO 500MB MOISTURE AND 700 TO 500MB LIFT WL MOVE
FROM SOUTHWEST TO NORTHEAST ACRS OUR CWA BTWN 12Z-15Z WEDS.
THERMAL PROFILES SUPPORT A MIX OF SNOW...SLEET...AND FREEZING
RAIN...ESPECIALLY EAST OF THE GREEN MTNS...BUT TOTAL QPF AMOUNTS
ASSOCIATED WITH INITIAL BAND OF PRECIP WL BE LIGHT AND ONLY A
DUSTING OF SNOW/SLEET IS ANTICIPATED. LOW LEVEL SOUTH TO SOUTHWEST
FLW WL QUICKLY ADVECT WARMER TEMPS ACRS OUR CWA BY 15Z WEDS...WITH
85H TEMPS RISING BTWN +3C AND +5C...AND 925MB TEMPS NEAR +3C. IN
ADDITION...GIVEN POSITION OF SFC HIGH PRES WITH NO BLOCKING
SIGNATURE IN THE SLP FIELDS...FEEL COLD AIR WL QUICKLY RETREAT.
ALSO...LIMITED SNOW PACK AND DEVELOPING SOUTHERLY FLW WL HELP TO
ERODE LLVL COLD AIR...BEFORE HEAVIER PRECIP ARRIVES AFT 18Z WEDS.
THE BETTER DYNAMICS ASSOCIATED WITH DECAYING MID/UPPER LVL
CIRCULATION AND POTENT 5H VORT MOVES ACRS OUR CWA BTWN 21Z-06Z.
THIS ULVL SUPPORT COMBINED WITH GOOD 850 TO 500MB Q-VECTOR
CONVERGENCE AND GOOD AVAILABLE MOISTURE WITH PWS APPROACHING
0.75"...WL RESULT IN A PERIOD OF OCCASIONAL LIGHT RAIN ACRS OUR
CWA ON WEDS NIGHT. ONCE AGAIN...A FEW POCKETS OF FREEZING RAIN WL
BE POSSIBLE ACRS EASTERN VT/NEK...BUT NOT ANTICIPATING ANY ICE
ACCUMULATION ATTM. TEMPS WL WARM INTO THE L40S CPV TO M30S
NEK/EASTERN VT ON WEDS. LITTLE CHANGE IN TEMPS IS EXPECTED ON WEDS
NIGHT WITH CLOUDS AND PRECIP EXPECTED. SFC COLD FRNT APPROACHES
NORTHERN CWA BY 12Z THURS...WITH TIGHT THERMAL GRADIENT. THIS WL
PUSH ACRS OUR FA ON THURS...WITH COOLER TEMPS AND THE CHANCE FOR
RAIN/SNOW SHOWERS. UNFORTUNATELY...AS THE AIR BECMS COLD ENOUGH TO
SUPPORT SNOW...THE BEST MOISTURE MOVES TO OUR EAST. NOT
ANTICIPATING MUCH SNOW ACCUMULATION...MAYBE AN INCH OR SO IN THE
FAVORABLE UPSLOPE REGIONS OF THE DACKS/GREEN MTNS. TEMPS WL START
NEAR 40F IN THE CPV...BUT WL FALL INTO THE 30S AS NORTH WINDS AND
LLVL CAA DEVELOPS. OTHERWISE...MAINLY 30S WL BE THE HIGHS ON THURS
ACRS THE MTNS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 230 PM EST MONDAY...DEVELOPING COLD FRONT NORTH OF THE
INTERNATIONAL BORDER WILL DROP SOUTH INTO FORECAST LATER THURSDAY
NIGHT. MEANWHILE...LOW PRESSURE WILL TRACK SOUTH OF THE AREA PASSING
OFF MID ATLANTIC COAST. EXPECT SOME SNOW SHOWERS ASSOCIATED WITH
COLD FRONT TO AFFECT NORTHERN ZONES...WITH LIGHT SNOW ASSOCIATED
WITH LOW TO OUR SOUTH POSSIBLY AFFECTING SOUTHERN ZONES. ALL ADDS
UP TO CHANCE POPS...MAINLY AFTER MIDNIGHT. LOW DEPARTS OFFSHORE FRIDAY
MORNING...BUT THERE WILL BE A CONTINUED CHANCE FOR A FEW SNOW SHOWERS
AS THE COLD FRONT DEPRESSES SOUTH OF FORECAST AREA BY AFTERNOON.
HIGH PRESSURE BUILDING ACROSS ONTARIO INTO QUEBEC LATER FRIDAY
INTO SATURDAY WILL BRING MAINLY DRY WEATHER TO THE NORTH COUNTRY
ALONG WITH COLDER TEMPERATURES. LOWS FRIDAY NIGHT UNDER MAINLY CLEAR
SKIES WILL BE MAINLY IN THE TEENS...AND HIGHS ON SATURDAY IN THE
UPPER 20S TO LOWER 30S.
SITUATION BECOMES MORE COMPLICATED SATURDAY NIGHT AS HIGH MOVES
INTO EASTERN CANADA AND SHORTWAVE AND ASSOCIATED SURFACE LOW LIFT
NORTHEAST FROM THE TENNESSEE VALLEY. SOME RATHER SIGNIFICANT
DIFFERENCES BETWEEN GFS AND ECMWF REGARDING THIS SYSTEM...
ESPECIALLY WITH RESPECT TO TIMING. GFS MUCH FASTER...BRINGING
PRECIPITATION IN QUICKLY SATURDAY NIGHT AND EXITING CHRISTMAS
MORNING. TEMP PROFILE ON GFS WARMS ENOUGH SO THAT PTYPE MAY BECOME
AN ISSUE. ECMWF MAINTAINS DRY CONDITIONS SATURDAY NIGHT WITH BULK
OF PCPN SUNDAY PM/EVENING...AND MAINLY SNOW AS TEMPS SLIGHTLY
COOLER. HAVE ATTEMPTED TO BLEND THE TWO MODELS. LOW CONFIDENCE IN
TIMING OF THIS SYSTEM...BUT CONFIDENCE INCREASING THAT THERE WILL
BE AN EVENT IN THE SATURDAY NIGHT TO SUNDAY NIGHT TIMEFRAME. HAVE
GONE WITH 40 POPS FOR SNOW OR SNOW/RAIN MIX ACROSS THE AREA...SO
THERE IS HOPE FOR THOSE LOOKING FOR A WHITE CHRISTMAS. THOSE WITH
TRAVEL INTERESTS AROUND CHRISTMAS DAY SHOULD MONITOR LATEST
FORECASTS. DRIER CONDITIONS EXPECTED MONDAY...ALTHOUGH THERE MAY
BE A FEW SNOW SHOWERS...ESPECIALLY OVER NORTHERN SECTIONS.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
THROUGH 06Z WEDNESDAY...COLD FRONT HAS PUSHED SOUTH OF FRECAST
AREA. INTERMITTENT LIGHT SNOW SHOWERS WILL BE ENDING BY 08Z WITH
AREAS OF MVFR CIGS THROUGH ABOUT 12Z. EXPECT CIGS IMPROVING TO VFR
ALONG WITH A DECREASE IN CLOUD COVER...WITH CLEAR SKIES BY 17Z ALL
TAF SITES. VFR CONDITIONS WILL THEN PREVAIL FOR THE REST OF THE
PERIOD. EXPECT GUSTY NORTHWEST WINDS TO SLACKEN INTO THE 5-10KT
RANGE BY MID-MORNING.
OUTLOOK 06Z WEDNESDAY THROUGH SATURDAY...
VFR THRU 10Z WEDNESDAY...THEN MVFR CEILINGS AND MIXED PCPN
DEVELOPING EARLY WEDNESDAY WITH APPROACHING WARM FRONT. LIGHT
SNOW/SLEET MIX WILL CHANGE TO RAIN BY WEDNESDAY AFTERNOON. MVFR
WITH PERIODS OF IFR CEILINGS EXPECTED MUCH OF WEDNESDAY AND
WEDNESDAY NIGHT WITH HIR TRRN OBSCD. THURSDAY WILL FEATURE PARTIAL
CLEARING WITH SOME MVFR CEILINGS...ESPECIALLY AT MPV/SLK. COLD
FRONT BRINGS CHANCE SNOW SHOWERS WITH BRIEF MVFR CONDITIONS FRIDAY
MORNING. HIGH PRESSURE AND VFR CONDITIONS EXPECTED FRIDAY PM/NIGHT
AND CONTINUING THROUGH MUCH OF SATURDAY. NEXT FRONTAL SYSTEM
APPROACHES FROM THE SOUTHWEST LATE SATURDAY WITH IFR RAIN OR SNOW
POSSIBLE SATURDAY NIGHT.
&&
.MARINE...
STRONG SOUTH TO SOUTHWEST WINDS CONTINUE THIS AFTERNOON ON LAKE
CHAMPLAIN WITH 20 TO 30 KNOTS STILL BEING OBSERVED AT COLCHESTER
REEF AT 3 PM. THIS IS EXPECTED TO DECREASE SLIGHTLY TO 15 TO 25
KNOTS THIS EVENING. WINDS WILL THEN TURN TO THE WEST AND THEN
NORTHWEST OVERNIGHT FROM 15 TO 25 KNOTS. THUS THE LAKE WIND
ADVISORY CONTINUES THROUGH TONIGHT. THE NORTHWEST WINDS WILL HANG
ON INTO TUESDAY MORNING BEFORE WEAKENING DURING THE DAY WITH 5 TO
15 KNOT WINDS EXPECTED IN THE AFTERNOON. WAVES WILL BE 3 TO 5 FEET
THIS AFTERNOON...DECREASING TO 1 TO 3 FEET OVERNIGHT.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...TABER
NEAR TERM...TABER
SHORT TERM...TABER
LONG TERM...RJS
AVIATION...RJS
MARINE...
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
600 PM EST TUE DEC 20 2011
.SYNOPSIS...
A COLD FRONT WILL SLOWLY APPROACH THE AREA WEDNESDAY AND THURSDAY
...THEN STALL ACROSS THE AREA THROUGH THE WEEKEND. WAVES OF LOW
PRESSURE WILL RIDE ALONG THIS FRONT...RESULTING WITH INCREASING
CHANCES FOR PRECIPITATION. THE PROSPECTS FOR MEASURABLE RAINFALL
WILL INCREASE AS THE WEEK PROGRESSES WITH THE BEST CHANCE EARLY IN
THE WEEKEND. HIGH PRESSURE WILL FINALLY REACH THE AREA EARLY IN THE
NEW WORK WEEK.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 545 PM TUESDAY...HAVE INCREASED CLOUD COVER ACROSS ALL OF THE
ILM CWA. THIS BASED ON LATEST SAT IMAGERY TRENDS AND THE LATEST 18Z
MODEL RUNS. LATEST HRRR KEEPS THE MAJORITY OF THE PCPN TONIGHT WEST
OF THE ILM CWA. BEST PCPN CHANCES ACROSS THE ILM CWA WILL OCCUR WEST
OF THE I-95 CORRIDOR. 5H S/W TROF AND ASSOCIATED UVVS MOVING
NE-WARD...WILL PASS IN CLOSE PROXIMITY TO WARRANT LOW CHANCE POPS
WELL INLAND. EAST OF I-95 AND TO THE COAST...ISOLATED -SHRA AT BEST.
WIDESPREAD 50S FOR LOWS LOOK GOOD EARLY IN THE NIGHT...WITH TEMPS
EITHER STEADY OR INCREASING SLIGHTLY AFTER MIDNIGHT DUE TO WAA AND
THE CLOUD COVER.
PREVIOUS DISCUSSION.............................................
AS OF 3 PM TUESDAY...LOW LEVEL ADVECTION OF WARM AND MOIST AIR AT
ODDS WITH MID LEVEL DRYNESS IN TRYING TO GENERATE PRECIPITATION
THROUGH THE PERIOD. MOST OF THE ADVECTION WILL JUST GO TO AN
INCREASE IN CLOUDINESS...ALTHOUGH SLIGHT CHANCE POPS CANNOT BE
RULED OUT. SUSPECT THAT NON-MEASURABLE SPRINKLES MORE LIKELY THAN
ANYTHING HIGHER. THE EXTENSIVE CLOUD COVER PAIRED WITH THE WAA
WILL KEEP LOWS EXCEPTIONALLY MILD...CLOSER TO NORMAL HIGH TEMPS
FOR THE SEASON...WITH READINGS GENERALLY IN THE MID 50S.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...A LARGE AREA OF HIGH PRESSURE WILL BE CENTERED
ACROSS THE WESTERN ATLANTIC. THE WESTERN PERIPHERY OF THIS HIGH WILL
HANG ON ACROSS THE EASTERN CAROLINAS THROUGH THE MID-TERM. AT THE
SAME TIME...A VERY DEEP TROUGH WILL CARVE OUT ACROSS THE WESTERN
UNITED STATES. ONE AREA OF LOW PRESSURE WILL PASS WELL N OF THE AREA
ON WED AS ANOTHER AREA OF LOW PRESSURE EJECTS OUT OF THE FOUR
CORNERS REGION AND PASSES JUST N OF THE AREA THU AND THU NIGHT. AS
EACH ONE OF THESE SYSTEMS RIDE OVER THE TOP OF THE RIDGE THEY WILL
AID IN FLATTENING IT OUT...SETTING UP THE STAGE FOR PERHAPS SOME
MEANINGFUL RAIN JUST BEYOND THIS FORECAST PERIOD.
A DEEP AND WARM SW FLOW WILL KEEP CONDITIONS UNSETTLED THIS PERIOD
WITH CLOUDS DOMINATING THE SKY. WHILE MEASURABLE RAINFALL CAN NOT BE
RULED OUT AT ANY TIME DURING THIS PERIOD...AT THIS POINT IT IS VERY
DIFFICULT TO HONE IN ON A TIME WHEN THE CHANCE FOR SHOWERS WILL BE
HIGHEST. HOWEVER...WE WILL CARRY THE HIGHEST POPS LATER THU AND THU
NIGHT AS FOUR CORNERS LOW MAKES ITS CLOSEST APPROACH. HOWEVER...
AGAIN...TIMING IS VERY UNCERTAIN AT THIS POINT.
GIVEN DEWPOINTS IN THE LOWER TO MID 60S WILL BE ADVECTING
NORTHWARD...WE DO EXPECT PATCHY SEA FOG TO DEVELOP. GIVEN THE
TRAJECTORIES...SOME OF THIS FOG SHOULD SKIRT THE COASTAL AREAS...
ESPECIALLY ACROSS BRUNSWICK COUNTY. INTRODUCED PATCHY FOG ALONG THE
COAST FOR LATER WED S...SPREADING UP THE COAST WED NIGHT AND THU.
THIS FOG MAY EVENTUALLY GROW MORE WIDESPREAD AND DENSE AT THE COAST
AS WARM AND MOIST FLOW PERSISTS ACROSS THE COOL SHELF WATERS.
DAYTIME HIGHS AND LOWS WILL BE WELL ABOVE NORMAL THROUGH THE PERIOD.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 3 PM TUESDAY...MUCH OF THE PERIOD REMAINS UNSETTLED. A COLD
FRONT...LAYING PARALLEL TO FLOW ALOFT...WILL BE STALLED OVER THE
AREA FRI AND THEN JUST OFF THE COAST SAT/SUN. SEVERAL WEAK
SURFACE WAVES WILL TRAVEL NORTHEAST ALONG THE BOUNDARY. ADDITIONALLY
THERE WILL BE WEAK SHORTWAVES TRAVELING UP THE WESTERN SIDE OF THE
5H RIDGE DURING THE FIRST HALF OF THE PERIOD. TIMING THESE SUBTLE
FEATURES IS DIFFICULT AT BEST SO DID NOT MAKE A LOT OF CHANGES TO
POP GRIDS.
SUN INTO MON THE MEDIUM RANGE GUIDANCE STARTS TO DIVERGE. THE GFS
SHOWS A MORE PROGRESSIVE ZONAL PATTERN DEVELOPING WHILE THE
ECMWF/CANADIAN SHOW MORE AMPLIFICATION. THE RESULT OF THIS IS THE
GFS WANTS TO BRING IN ANOTHER SYSTEM BEFORE THE END OF THE PERIOD
WHILE THE ECMWF/CANADIAN SOLUTIONS DO NOT. THE SLOWER ECMWF SOLUTION
IS FAVORED WHICH KEEPS THE END OF THE PERIOD DRY.
TEMPERATURES ABOVE TO WELL ABOVE CLIMO CONTINUE INTO THE WEEKEND
DESPITE CLOUD COVER AND THREAT OF PRECIP. ONCE THE FRONT PUSHES OFF
THE COAST...SUN INTO MON...TEMPERATURES WILL DROP BELOW CLIMO
THROUGH THE END OF THE PERIOD.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
AS OF 00Z...MOISTURE WILL BE ON THE INCREASE AS A COLD FRONT SLOWLY
APPROACHES THE REGION. MODERATE UNCERTAINTY WITH RESPECT TO CEILING
HEIGHTS OVERNIGHT. THE NAM IS THE MOST PESSIMISTIC...WITH IFR
PREDOMINATE AFTER MIDNIGHT. THINK THIS MAY BE OVERDONE...GIVEN THAT
IT ALSO SHOWING LOW VISIBILITIES. WILL GO WITH A LOW MVFR
CEILING...MAINLY AT THE INLAND TERMINALS.
DEEP MOISTURE MOVES INTO THE WESTERN CWA BY MIDDAY WEDNESDAY...WITH
A DECENT CHANCE FOR PRECIPITATION. ANY RAIN WILL LIKELY BY
LIGHT...WITH LITTLE REDUCTION IN VISIBILITY. LIKEWISE CEILINGS WILL
REMAIN MVFR TO VFR...WITH A LOT OF 4K CEILINGS NEAR THE SUBSIDENCE
INVERSION. SOUTHERLY GRADIENT WILL INCREASE...WITH GUSTY WINDS
EXPECTED BY LATE MORNING.
EXTENDED OUTLOOK...LOW CONFIDENCE IN MORNING FOG THURSDAY. MORE RAIN
WITH ASSOCIATED RESTRICTIONS POSSIBLE FRIDAY/SATURDAY. VFR EXPECTED
SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 545 PM TUESDAY...WAA UNDER S-SW WINDS WILL RULE TONIGHT.
LATEST NAM INDICATES WAA WINDS AT 925MB INCREASING TO 25-30 KT AFTER
MIDNIGHT THROUGH DAYBREAK WEDNESDAY. WITH SSTS ACROSS THE SHELF
WATERS IN THE 50S...THE HIGHER WINDS ALOFT WILL HAVE A DIFFICULT
TIME MIXING TO THE OCEAN SFC. AS A RESULT...WILL INDICATE S-SW WINDS
INCREASING ONLY TO 10-15 KT OVERNIGHT. SEAS 2 TO 3 FT...WILL
INCREASE ONLY TO 2 TO 4 FT...EXCEPT UP TO 5 FT ACROSS THE OUTER
WATERS OFF CAPE FEAR. THE INCREASE IN SEAS OVERNIGHT WILL MAINLY
COME FROM THE HIGHER WINDS AND RESULTANT SEAS OFFSHORE...WHERE SSTS
NEAR 70...BLEED INTO THE COASTAL WATERS.
PREVIOUS DISCUSSION...............................................
AS OF 3 PM TUESDAY...BERMUDA HIGH PRESSURE MORE TYPICAL OF WARM
SEASON TO REMAIN ANCHORED FIRMLY IN PLACE THROUGH THE PERIOD. WIND
WILL THUS BE SOUTHWESTERLY AND WILL TEND TO PICK UP INTO THE 10 TO
15 KT RANGE. THIS INCREASE IN WINDS WILL TRANSLATE INTO A SMALL
INCREASE IN SEAS. THE SOUTHWESTERLY FLOW IS LARGELY PARALLEL TO
THE COAST SO THE MOST SIGNIFICANT BUILDING OF SEAS...ABOUT A
FOOT...WILL BE WELL AWAY FROM SHORE WHILE THOSE NEAR SHORE BUILD
LESS. IN THE END A GENERAL 2 TO 4 FT RANGE IS EXPECTED FOR THE
OVERNIGHT PERIOD.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...WINDS WILL BE FROM THE SW THROUGH THE PERIOD.
SW FLOW ALOFT WILL BE ROBUST WITH JETTING AT TIMES INCREASING WINDS
TO 40+ KT ALOFT. HOWEVER...THESE WINDS WILL NOT EFFICIENTLY MIX DOWN
GIVEN THE COOL WATER TEMPS...THUS WINDS THROUGH THE PERIOD SHOULD
NOT EXCEED 15 TO 20 KT. SEAS WILL NOT EXCEED 3 TO 5 FT.
AS DEWPOINTS IN THE LOWER TO MID 60S ADVECT ACROSS THE WATERS...
PATCHY SEA FOG IS EXPECTED TO DEVELOP ACROSS THE SOUTHERN WATERS WED
AFTERNOON AND THEN SPREAD N THROUGH THU. THE COVERAGE OF FOG MAY
INCREASE WITH TIME AND GROW DENSER AS WARM AND MOIST FLOW PERSISTS
ACROSS THE COOL SHELF WATERS.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 3 PM TUESDAY...STALLED FRONT IN THE VICINITY WILL KEEP WIND
DIRECTION FORECAST THROUGH THE PERIOD QUITE TRICKY. FRI THE FRONT
WILL BE WEST OF THE WATERS WITH SOUTHWEST FLOW IN PLACE. FRONT
SHIFTS OFFSHORE FRI NIGHT INTO SAT WITH LIGHT NORTHERLY FLOW
DEVELOPING. FRONT REMAINS STALLED JUST OFF THE COAST THROUGH THE
END OF THE PERIOD...WITH SPEEDS 10 TO 15 KT. SEAS WILL RUN 3 TO 5
FT THROUGH THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...DCH/MBB
SHORT TERM...RJD
LONG TERM...III
AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
545 PM EST TUE DEC 20 2011
.SYNOPSIS...
A COLD FRONT WILL SLOWLY APPROACH THE AREA WEDNESDAY AND THURSDAY
...THEN STALL ACROSS THE AREA THROUGH THE WEEKEND. WAVES OF LOW
PRESSURE WILL RIDE ALONG THIS FRONT...RESULTING WITH INCREASING
CHANCES FOR PRECIPITATION. THE PROSPECTS FOR MEASURABLE RAINFALL
WILL INCREASE AS THE WEEK PROGRESSES WITH THE BEST CHANCE EARLY IN
THE WEEKEND. HIGH PRESSURE WILL FINALLY REACH THE AREA EARLY IN THE
NEW WORK WEEK.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 545 PM TUESDAY...HAVE INCREASED CLOUD COVER ACROSS ALL OF THE
ILM CWA. THIS BASED ON LATEST SAT IMAGERY TRENDS AND THE LATEST 18Z
MODEL RUNS. LATEST HRRR KEEPS THE MAJORITY OF THE PCPN TONIGHT WEST
OF THE ILM CWA. BEST PCPN CHANCES ACROSS THE ILM CWA WILL OCCUR WEST
OF THE I-95 CORRIDOR. 5H S/W TROF AND ASSOCIATED UVVS MOVING
NE-WARD...WILL PASS IN CLOSE PROXIMITY TO WARRANT LOW CHANCE POPS
WELL INLAND. EAST OF I-95 AND TO THE COAST...ISOLATED -SHRA AT BEST.
WIDESPREAD 50S FOR LOWS LOOK GOOD EARLY IN THE NIGHT...WITH TEMPS
EITHER STEADY OR INCREASING SLIGHTLY AFTER MIDNIGHT DUE TO WAA AND
THE CLOUD COVER.
PREVIOUS DISCUSSION.............................................
AS OF 3 PM TUESDAY...LOW LEVEL ADVECTION OF WARM AND MOIST AIR AT
ODDS WITH MID LEVEL DRYNESS IN TRYING TO GENERATE PRECIPITATION
THROUGH THE PERIOD. MOST OF THE ADVECTION WILL JUST GO TO AN
INCREASE IN CLOUDINESS...ALTHOUGH SLIGHT CHANCE POPS CANNOT BE
RULED OUT. SUSPECT THAT NON-MEASURABLE SPRINKLES MORE LIKELY THAN
ANYTHING HIGHER. THE EXTENSIVE CLOUD COVER PAIRED WITH THE WAA
WILL KEEP LOWS EXCEPTIONALLY MILD...CLOSER TO NORMAL HIGH TEMPS
FOR THE SEASON...WITH READINGS GENERALLY IN THE MID 50S.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...A LARGE AREA OF HIGH PRESSURE WILL BE CENTERED
ACROSS THE WESTERN ATLANTIC. THE WESTERN PERIPHERY OF THIS HIGH WILL
HANG ON ACROSS THE EASTERN CAROLINAS THROUGH THE MID-TERM. AT THE
SAME TIME...A VERY DEEP TROUGH WILL CARVE OUT ACROSS THE WESTERN
UNITED STATES. ONE AREA OF LOW PRESSURE WILL PASS WELL N OF THE AREA
ON WED AS ANOTHER AREA OF LOW PRESSURE EJECTS OUT OF THE FOUR
CORNERS REGION AND PASSES JUST N OF THE AREA THU AND THU NIGHT. AS
EACH ONE OF THESE SYSTEMS RIDE OVER THE TOP OF THE RIDGE THEY WILL
AID IN FLATTENING IT OUT...SETTING UP THE STAGE FOR PERHAPS SOME
MEANINGFUL RAIN JUST BEYOND THIS FORECAST PERIOD.
A DEEP AND WARM SW FLOW WILL KEEP CONDITIONS UNSETTLED THIS PERIOD
WITH CLOUDS DOMINATING THE SKY. WHILE MEASURABLE RAINFALL CAN NOT BE
RULED OUT AT ANY TIME DURING THIS PERIOD...AT THIS POINT IT IS VERY
DIFFICULT TO HONE IN ON A TIME WHEN THE CHANCE FOR SHOWERS WILL BE
HIGHEST. HOWEVER...WE WILL CARRY THE HIGHEST POPS LATER THU AND THU
NIGHT AS FOUR CORNERS LOW MAKES ITS CLOSEST APPROACH. HOWEVER...
AGAIN...TIMING IS VERY UNCERTAIN AT THIS POINT.
GIVEN DEWPOINTS IN THE LOWER TO MID 60S WILL BE ADVECTING
NORTHWARD...WE DO EXPECT PATCHY SEA FOG TO DEVELOP. GIVEN THE
TRAJECTORIES...SOME OF THIS FOG SHOULD SKIRT THE COASTAL AREAS...
ESPECIALLY ACROSS BRUNSWICK COUNTY. INTRODUCED PATCHY FOG ALONG THE
COAST FOR LATER WED S...SPREADING UP THE COAST WED NIGHT AND THU.
THIS FOG MAY EVENTUALLY GROW MORE WIDESPREAD AND DENSE AT THE COAST
AS WARM AND MOIST FLOW PERSISTS ACROSS THE COOL SHELF WATERS.
DAYTIME HIGHS AND LOWS WILL BE WELL ABOVE NORMAL THROUGH THE PERIOD.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 3 PM TUESDAY...MUCH OF THE PERIOD REMAINS UNSETTLED. A COLD
FRONT...LAYING PARALLEL TO FLOW ALOFT...WILL BE STALLED OVER THE
AREA FRI AND THEN JUST OFF THE COAST SAT/SUN. SEVERAL WEAK
SURFACE WAVES WILL TRAVEL NORTHEAST ALONG THE BOUNDARY. ADDITIONALLY
THERE WILL BE WEAK SHORTWAVES TRAVELING UP THE WESTERN SIDE OF THE
5H RIDGE DURING THE FIRST HALF OF THE PERIOD. TIMING THESE SUBTLE
FEATURES IS DIFFICULT AT BEST SO DID NOT MAKE A LOT OF CHANGES TO
POP GRIDS.
SUN INTO MON THE MEDIUM RANGE GUIDANCE STARTS TO DIVERGE. THE GFS
SHOWS A MORE PROGRESSIVE ZONAL PATTERN DEVELOPING WHILE THE
ECMWF/CANADIAN SHOW MORE AMPLIFICATION. THE RESULT OF THIS IS THE
GFS WANTS TO BRING IN ANOTHER SYSTEM BEFORE THE END OF THE PERIOD
WHILE THE ECMWF/CANADIAN SOLUTIONS DO NOT. THE SLOWER ECMWF SOLUTION
IS FAVORED WHICH KEEPS THE END OF THE PERIOD DRY.
TEMPERATURES ABOVE TO WELL ABOVE CLIMO CONTINUE INTO THE WEEKEND
DESPITE CLOUD COVER AND THREAT OF PRECIP. ONCE THE FRONT PUSHES OFF
THE COAST...SUN INTO MON...TEMPERATURES WILL DROP BELOW CLIMO
THROUGH THE END OF THE PERIOD.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 18Z...EXPECT VFR CONDITIONS TO PERSIST INTO THE OVERNIGHT
HOURS ON W-SW FLOW OF 5 TO 10 KT. S TO SW FLOW AHEAD OF AN
APPROACHING COLD FRONT COULD BRING SCATTERED SHOWERS TO THE AREA
AFTER 00Z BUT THE PROBABILITY LOOKS TOO LOW TO INCLUDE IN THE TAFS
PRESENTLY. THERE IS SOME POTENTIAL FOR AN IFR STRATUS EVENT
TONIGHT...ESPECIALLY AT INLAND TERMINALS. WINDS OVERNIGHT WILL
BECOME SOUTHERLY AND DECREASE TO 3-6 KTS. SHOWERS REMAIN POSSIBLE
ALL AREAS AFTER 12Z WITH MVFR CIGS EXPECTED AT ALL TERMINALS.
SHOWERS WERE ONLY INCLUDED AT INLAND TAF SITES IN THE 12 TO 18Z
WINDOW AS THE PROBABILITY IS HIGHEST AT THOSE TERMINALS.
EXTENDED OUTLOOK...LOW CONFIDENCE IN MORNING FOG THURSDAY. MORE RAIN
WITH ASSOCIATED RESTRICTIONS POSSIBLE FRIDAY/SATURDAY. VFR EXPECTED
SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 545 PM TUESDAY...WAA UNDER S-SW WINDS WILL RULE TONIGHT.
LATEST NAM INDICATES WAA WINDS AT 925MB INCREASING TO 25-30 KT AFTER
MIDNIGHT THROUGH DAYBREAK WEDNESDAY. WITH SSTS ACROSS THE SHELF
WATERS IN THE 50S...THE HIGHER WINDS ALOFT WILL HAVE A DIFFICULT
TIME MIXING TO THE OCEAN SFC. AS A RESULT...WILL INDICATE S-SW WINDS
INCREASING ONLY TO 10-15 KT OVERNIGHT. SEAS 2 TO 3 FT...WILL
INCREASE ONLY TO 2 TO 4 FT...EXCEPT UP TO 5 FT ACROSS THE OUTER
WATERS OFF CAPE FEAR. THE INCREASE IN SEAS OVERNIGHT WILL MAINLY
COME FROM THE HIGHER WINDS AND RESULTANT SEAS OFFSHORE...WHERE SSTS
NEAR 70...BLEED INTO THE COASTAL WATERS.
PREVIOUS DISCUSSION...............................................
AS OF 3 PM TUESDAY...BERMUDA HIGH PRESSURE MORE TYPICAL OF WARM
SEASON TO REMAIN ANCHORED FIRMLY IN PLACE THROUGH THE PERIOD. WIND
WILL THUS BE SOUTHWESTERLY AND WILL TEND TO PICK UP INTO THE 10 TO
15 KT RANGE. THIS INCREASE IN WINDS WILL TRANSLATE INTO A SMALL
INCREASE IN SEAS. THE SOUTHWESTERLY FLOW IS LARGELY PARALLEL TO
THE COAST SO THE MOST SIGNIFICANT BUILDING OF SEAS...ABOUT A
FOOT...WILL BE WELL AWAY FROM SHORE WHILE THOSE NEAR SHORE BUILD
LESS. IN THE END A GENERAL 2 TO 4 FT RANGE IS EXPECTED FOR THE
OVERNIGHT PERIOD.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 PM TUESDAY...WINDS WILL BE FROM THE SW THROUGH THE PERIOD.
SW FLOW ALOFT WILL BE ROBUST WITH JETTING AT TIMES INCREASING WINDS
TO 40+ KT ALOFT. HOWEVER...THESE WINDS WILL NOT EFFICIENTLY MIX DOWN
GIVEN THE COOL WATER TEMPS...THUS WINDS THROUGH THE PERIOD SHOULD
NOT EXCEED 15 TO 20 KT. SEAS WILL NOT EXCEED 3 TO 5 FT.
AS DEWPOINTS IN THE LOWER TO MID 60S ADVECT ACROSS THE WATERS...
PATCHY SEA FOG IS EXPECTED TO DEVELOP ACROSS THE SOUTHERN WATERS WED
AFTERNOON AND THEN SPREAD N THROUGH THU. THE COVERAGE OF FOG MAY
INCREASE WITH TIME AND GROW DENSER AS WARM AND MOIST FLOW PERSISTS
ACROSS THE COOL SHELF WATERS.
LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 3 PM TUESDAY...STALLED FRONT IN THE VICINITY WILL KEEP WIND
DIRECTION FORECAST THROUGH THE PERIOD QUITE TRICKY. FRI THE FRONT
WILL BE WEST OF THE WATERS WITH SOUTHWEST FLOW IN PLACE. FRONT
SHIFTS OFFSHORE FRI NIGHT INTO SAT WITH LIGHT NORTHERLY FLOW
DEVELOPING. FRONT REMAINS STALLED JUST OFF THE COAST THROUGH THE
END OF THE PERIOD...WITH SPEEDS 10 TO 15 KT. SEAS WILL RUN 3 TO 5
FT THROUGH THE PERIOD.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...DCH/MBB
SHORT TERM...RJD
LONG TERM...III
AVIATION...RAN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
402 PM EST TUE DEC 20 2011
.SYNOPSIS...
A COLD FRONT STALLED ACROSS THE MASON DIXON LINE WILL SLOWLY
LIFT NORTH AS A WARM FRONT TONIGHT AND WEDNESDAY. THIS WILL
PRODUCE PERIODS OF LIGHT RAIN OR DRIZZLE INTO THE EVENING HOURS.
LOW PRESSURE WILL MOVE THRU THE EASTERN GREAT LAKES ON
WEDNESDAY EVENTUALLY DRAGGING A COLD FRONT ACROSS THE REGION.
HIGH PRESSURE WILL MOVE INTO THE AREA ON THURSDAY FOLLOWED BY
MORE UNSETTLED WEATHER FOR LATE IN THE WEEK AND POTENTIALLY THE
CHRISTMAS WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
LATEST SFC ANALYSIS INDICATES A STALLED FRONT ALONG OR JUST SOUTH
OF THE MASON-DIXON LINE WITH LIGHT OVERRUNNING PRECIP STREAKING
EAST ACROSS MUCH OF MY FCST AREA. ANYTHING THAT FALLS OVER THE FAR
NORTH WHERE TEMPS ARE STILL CLOSE TO FREEZING MAY FALL AS
SNOW...BUT OVER MOST OF THE REGION WE ARE SEEING MAINLY LIGHT RAIN
OR DRIZZLE.
LATEST NAM AND HRRR SHOW A CHUNK OF LIGHT PRECIP BETWEEN NOW AND
ROUGHLY 00Z...WHEN ACTIVITY IS MADE TO TAPER OFF AND BECOME MORE
SCATTERED IN NATURE.
FROM THERE THE SREF AND NEW 12Z NAM/GFS DEVELOP ANOTHER SURGE OF
PRECIPITATION FOR THE AFTER MIDNIGHT PERIOD AS THE LEFT EXIT
REGION OF THE UPPER JET STARTS TO NOSE INTO THE REGION. THE
FORECAST GETS A LITTLE TRICKY OVER THE NORTHERN MOUNTAINS WHERE
SOME COLDER SPOTS COULD BOTTOM OUT JUST UNDER FREEZING. THIS WILL
CREATE THE POTENTIAL FOR A PERIOD OF LIGHT FREEZING RAIN OR DRIZZLE
BEFORE THE WARM ADVECTION WARMS UP ALL LOCATIONS LATER TONIGHT AND
EARLY WED. AT THIS POINT CONFIDENCE IS TOO LOW TO ISSUE ANY
HEADLINE PRODUCTS...BUT FOR NOW THE POTENTIAL HAS BEEN ADDRESSED
IN THE HWO.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
WED WILL SEE THE APPROACH OF A FAIRLY VIGOROUS MID LEVEL
SHORTWAVE AND ASSOCIATED SFC FRONTAL SYSTEM.
MODELS ARE QUICK TO ERODE STABILITY AS DEEP MOISTURE AND
INCREASING MID LEVEL LAPSE RATES SURGE INTO THE FCST AREA WITH THE
APPROACH OF THE LEFT EXIT REGION OF AN IMPRESSIVE MID/UPPER LEVEL
JET STREAK. WITH THE MODELS DEPICTING SOME RESPECTABLE CONVECTIVE
INSTABILITY...AND EVEN SOME INERTIAL INSTABILITY...CANNOT RULE OUT
EMBEDDED THUNDER AS THE SHORTWAVE AND FRONTAL SYSTEM MOVE THROUGH
DURING THE AFTERNOON AND EARLY EVENING.
LOW TO MID LEVEL WIND FIELDS WILL BE ON THE INCREASE THROUGHOUT
THE DAY AS THE UPPER WAVE BARRELS OUR WAY. SPC HAS THE REGION IN
THE "SEE TEXT" PORTION OF THE OUTLOOK ACKNOWLEDGING THE
POSSIBILITY OF STRONG WIND FIELDS BEING TAPPED BY THE CONVECTION
AND PERHAPS CAUSING LOCALLY DAMAGING WIND GUSTS.
AFTER SOME INITIAL COOL AIR DAMMING...HIGHS ARE EXPECTED TO MAKE
IT INTO THE 40S AND 50S...WHICH WILL BE WELL ABOVE MID DECEMBER
NORMALS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
VERY ACTIVE SOUTHERN JET STREAM WILL CONTINUE A COMPLEX FORECAST
SCENARIO FOR THE MID ATLANTIC STATES THROUGH THE LONG TERM
PERIOD. MODEL GUIDANCE KEEPS THE MEAN UPPER TROF OVER THE WESTERN
U.S. THROUGH MUCH OF THE PD...WITH SWRLY FLOW DOMINATING THE
EASTERN HALF OF THE COUNTRY. NOT UNTIL MONDAY DOES THE ECMWF BRING A
PROGRESSIVE UPPER TROF INTO THE EASTERN U.S.
NUMEROUS SHORTWAVES WILL EJECT FROM THE SWRN UPPER TROF AND TRAVEL THROUGH
THE CENTER OF THE COUNTRY AND INTO OUR REGION. DURING THIS
FORECAST PD CURRENT TIMING BRINGS ONE WAVE/SFC LOW THROUGH ON
FRIDAY AND ANOTHER ON SUNDAY.
WHILE THE NORTHERN JET STREAM WILL ALSO BE ACTIVE...BRINGING
SHOTS OF COLD AIR TOWARD PA...THE DOMINANT SWRLY FLOW WILL LEAD TO
MOST PCPN BEING IN THE FORM OF RAIN. BEST CHANCE OF ANY SNOW FALL
WILL BE ON THE TAIL END OF EACH SYSTEM. WHAT HAD LOOKED LIKE A
SHOT A MEASURABLE SNOW PREVIOUSLY...FOR CHRISTMAS DAY...CONTINUES
TO BE IN QUESTION AS THIS MORNINGS ECMWF IS NOW SIGNIFICANTLY
WARMER AND THE GFS IS ALMOST COMPLETELY DRY.
AFTER CHRISTMAS IT LOOKS DRIER AND COOLER AS THE TRAIN OF SRN
STREAM WAVES TAKES A BREAK.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
A STALLED FRONTAL BOUNDARY STRETCHED ACROSS THE PA/MD LINE WILL
BEGIN TO SLOWLY LIFT BACK TO THE NORTH LATER THIS AFTERNOON. THE
ASSOCIATED CLOUDS WILL KEEP CIGS LOW ACROSS THE STATE. EXPECT
PROLONGED IFR/LIFR CIGS AND VISIBILITIES AT BFD AND JST THROUGHOUT
MOST OF THE DAY. ELSEWHERE LOOK FOR MVFR TO IFR CIGS 005-020. CIGS
WILL DROP AGAIN OVERNIGHT AND STAY LOW THROUGH THE REMAINDER OF THE
TAF PERIOD AS THE FRONT LIFTS AND ANOTHER LOW PRESSURE SYSTEM MOVES
INTO THE OHIO VALLEY ON WEDNESDAY. EXPECT MVFR TO IFR RESTRICTIONS
WEDNESDAY WITH WIDESPREAD -RA AND A CHANCE OF TS IN THE SOUTHERN
PART OF THE STATE.
OUTLOOK...
WED...MVFR TO IFR RESTRICTIONS LKLY. WDSPRD -RA/CHC OF TS SRN PA.
THUR...NO SIG WX. MVFR CIGS PSBL WEST.
THUR NGT...RESTRICTIONS PSBL IN RA/SN AS WAVE MOVES THROUGH SOUTHERN MID-ATLC.
FRI-SUN...MVR TO IFR RESTRICTIONS POSSIBLE AS ANOTHER SYSTEM MOVES
THROUGH THE REGION.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE/GARTNER
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...DEVOIR/GARTNER
AVIATION...LA CORTE/STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
111 PM EST TUE DEC 20 2011
.SYNOPSIS...
A COLD FRONT STALLED ACROSS THE MASON DIXON LINE WILL SLOWLY
LIFT NORTH AS A WARM FRONT TONIGHT AND WEDNESDAY. THIS WILL
PRODUCE PERIODS OF LIGHT RAIN OR DRIZZLE INTO THE EVENING HOURS.
LOW PRESSURE WILL MOVE THRU THE EASTERN GREAT LAKES ON
WEDNESDAY EVENTUALLY DRAGGING A COLD FRONT ACROSS THE REGION.
HIGH PRESSURE WILL MOVE INTO THE AREA ON THURSDAY FOLLOWED BY
MORE UNSETTLED WEATHER FOR LATE IN THE WEEK AND POTENTIALLY THE
CHRISTMAS WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST SFC ANALYSIS INDICATES A STALLED FRONT ALONG OR JUST SOUTH
OF THE MASON-DIXON LINE WITH LIGHT OVERRUNNING PRECIP STREAKING
EAST ACROSS MUCH OF MY FCST AREA. ANYTHING THAT FALLS OVER THE FAR
NORTH WHERE TEMPS ARE STILL CLOSE TO FREEZING MAY FALL AS
SNOW...BUT OVER MOST OF THE REGION WE ARE SEEING MAINLY LIGHT RAIN
OR DRIZZLE.
LATEST NAM AND HRRR SHOW A CHUNK OF LIGHT PRECIP BETWEEN NOW AND
ROUGHLY 00Z...WHEN ACTIVITY IS MADE TO TAPER OFF AND BECOME MORE
SCATTERED IN NATURE.
FROM THERE THE SREF AND NEW 12Z NAM/GFS DEVELOP ANOTHER SURGE OF
PRECIPITATION FOR THE AFTER MIDNIGHT PERIOD AS THE LEFT EXIT
REGION OF THE UPPER JET STARTS TO NOSE INTO THE REGION. THE
FORECAST GETS A LITTLE TRICKY OVER THE NORTHERN MOUNTAINS WHERE
SOME COLDER SPOTS COULD BOTTOM OUT JUST UNDER FREEZING. THIS WILL
CREATE THE POTENTIAL FOR A PERIOD OF LIGHT FREEZING RAIN OR DRIZZLE
BEFORE THE WARM ADVECTION WARMS UP ALL LOCATIONS LATER TONIGHT AND
EARLY WED. AT THIS POINT CONFIDENCE IS TOO LOW TO ISSUE ANY
HEADLINE PRODUCTS...BUT FOR NOW THE POTENTIAL HAS BEEN ADDRESSED
IN THE HWO.
&&
.SHORT TERM /WEDNESDAY/...
WED WILL SEE THE APPROACH OF A FAIRLY VIGOROUS MID LEVEL
SHORTWAVE AND ASSOCIATED SFC FRONTAL SYSTEM.
MODELS ARE QUICK TO ERODE STABILITY AS DEEP MOISTURE AND
INCREASING MID LEVEL LAPSE RATES SURGE INTO THE FCST AREA WITH THE
APPROACH OF THE LEFT EXIT REGION OF AN IMPRESSIVE MID/UPPER LEVEL
JET STREAK. WITH THE MODELS DEPICTING SOME RESPECTABLE CONVECTIVE
INSTABILITY...AND EVEN SOME INERTIAL INSTABILITY...CANNOT RULE OUT
EMBEDDED THUNDER AS THE SHORTWAVE AND FRONTAL SYSTEM MOVE THROUGH
DURING THE AFTERNOON AND EARLY EVENING.
LOW TO MID LEVEL WIND FIELDS WILL BE ON THE INCREASE THROUGHOUT
THE DAY AS THE UPPER WAVE BARRELS OUR WAY. SPC HAS THE REGION IN
THE "SEE TEXT" PORTION OF THE OUTLOOK ACKNOWLEDGING THE
POSSIBILITY OF STRONG WIND FIELDS BEING TAPPED BY THE CONVECTION
AND PERHAPS CAUSING LOCALLY DAMAGING WIND GUSTS.
AFTER SOME INITIAL COOL AIR DAMMING...HIGHS ARE EXPECTED TO MAKE
IT INTO THE 40S AND 50S...WHICH WILL BE WELL ABOVE MID DECEMBER
NORMALS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
THE LONGER TERM WILL BE ACTIVE WITH NO FEWER THAN 3 WEATHER SYSTEMS
EJECTING FROM THE MEAN UPPER TROF POSITION OVER THE ROCKIES AND HIGH
PLAINS WEDNESDAY THROUGH SUNDAY. COLD AIR IS LACKING...KEEPING
PRECIPITATION TYPES MAINLY IN LIQUID FORM THROUGHOUT THE WEEK...BUT
COLDER AIR ON THE BACKSIDE OF EACH SYSTEM (ROUGHLY PASSING EVERY 1.5
DAYS) WILL BRING SOME CHANGEOVER TO SNOW SHOWER ACTIVITY.
MAIN CHANGES THIS MORNING BASED ON LATEST AVAILABLE GEFS PLUMES AND
OPERATIONAL RUNS/GUIDANCE WAS TO DECREASE EXTENT AND COVERAGE OF
MIXED PRECIPITATION DURING MIDWEEK. +8C TO +10C THERMAL RIDGE OVER
CENTRAL AND EASTERN PA WILL SUPPORT ISOLATED THUNDER WEDNESDAY
AFTERNOON AND LIKELY A NARROW COLD FRONTAL RAIN BAND. LATEST
GUIDANCE ALSO SUGGESTS THE COLD AIR BEHIND THIS SYSTEM FOR THURSDAY
IS NOT ALL THAT COLD...AND A CHANGEOVER MAY NOT EVEN OCCUR EVEN OVER
NORTHWEST PA...BEFORE THE NEXT SURGE OF WAA APPROACHES FROM THE
LOWER OHIO VALLEY AND CENTRAL APPALACHIANS LATE THURSDAY AND
THURSDAY NIGHT.
1026 MB TO 1028 MB SFC HIGH TRACKING EASTWARD FROM ONTARIO INTO
WESTERN QUEBEC LATE THURSDAY INTO FRIDAY WILL DIRECT COLDER AIR TO
THE EAST OF THE GREAT LAKES AND THERE MAY BE SOME MINOR ACCUMS ON
THE BACKSIDE OF THE SYSTEM OVER THE NORTHERN HALF OF CENTRAL PA AS
THE SFC LOW SCOOTS OFF OF THE MID ATLANTIC COASTLINE ON FRIDAY.
HIGH PRESSURE QUICKLY BUILDS EASTWARD ACROSS THE LOWER LAKES AND
INTO PA FRIDAY NIGHT AND FOR THE FIRST HALF OF SATURDAY BEFORE YET
ANOTHER WAVE OF LOW PRESSURE APPROACHES FROM THE SOUTHWEST LATE
CHRISTMAS EVE DAY. THIS TOO APPEARS TO BE MAINLY RAIN...ALTHOUGH
COLDER AIR WRAPPING AROUND THE STORM MAY AGAIN PROMOTE A CHANGE BACK
TO SNOW FOR CHRISTMAS MORNING. THERE IS SOME INDICATION THAT A MORE
PRONOUNCED LAKE EFFECT REGIME IS POSSIBLE FOR SUNDAY AND MONDAY AT
THE VERY END OF THE PERIOD...BUT THIS TOO IS LIKELY TO CHANGE AND
REMAINS A LOW CONFIDENCE SOLUTION AT THIS TIME.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
A STALLED FRONTAL BOUNDARY STRETCHED ACROSS THE PA/MD LINE WILL
BEGIN TO SLOWLY LIFT BACK TO THE NORTH LATER THIS AFTERNOON. THE
ASSOCIATED CLOUDS WILL KEEP CIGS LOW ACROSS THE STATE. EXPECT
PROLONGED IFR/LIFR CIGS AND VISIBILITIES AT BFD AND JST THROUGHOUT
MOST OF THE DAY. ELSEWHERE LOOK FOR MVFR TO IFR CIGS 005-020. CIGS
WILL DROP AGAIN OVERNIGHT AND STAY LOW THROUGH THE REMAINDER OF THE
TAF PERIOD AS THE FRONT LIFTS AND ANOTHER LOW PRESSURE SYSTEM MOVES
INTO THE OHIO VALLEY ON WEDNESDAY. EXPECT MVFR TO IFR RESTRICTIONS
WEDNESDAY WITH WIDESPREAD -RA AND A CHANCE OF TS IN THE SOUTHERN
PART OF THE STATE.
OUTLOOK...
WED...MVFR TO IFR RESTRICTIONS LKLY. WDSPRD -RA/CHC OF TS SRN PA.
THUR...NO SIG WX. MVFR CIGS PSBL WEST.
THUR NGT...RESTRICTIONS PSBL IN RA/SN AS WAVE MOVES THROUGH SOUTHERN MID-ATLC.
FRI-SUN...MVR TO IFR RESTRICTIONS POSSIBLE AS ANOTHER SYSTEM MOVES
THROUGH THE REGION.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...DEVOIR
AVIATION...LA CORTE/COLBERT
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
925 PM CST WED DEC 21 2011
.DISCUSSION.../ISSUED AT 925 PM CST...
MODEL AND RADAR DATA CONTINUE TO SHOW AN EARLIER AND FASTER DECREASE
IN THE LIGHT SNOW FROM THE NORTH THAN WE HAD BEEN GOING FOR EARLIER.
EVEN IN OUR SOUTHEAST CORNER PRECIPITATION SHOULD MOVE OUT BY 3 AM
IF NOW SOONER. CERTAINLY NOTHING LEFT FOR THURSDAY. EARLIER GFS AND
NEW NAM/NAM12 HAVE A BETTER HANDLE ON THE PRECIPITATION THAN THE
SHORT TERM MODELS RUC AND HRRR. BETTER COOLING STARTING FROM THE
NORTH THIS EVENING SO EARLIER FORECAST LOW TEMPERATURES LOOK OK OR
NOW THOUGH THEY COULD GET A LITTLE COLDER AROUND SUNRISE WITH FASTER
CLEARING. / WILLIAMS
&&
.AVIATION.../FOR THE 00Z TAF ISSUANCE/
LIGHT PRECIPITATION WILL CONTINUE TO SPREAD EASTWARD ACROSS THE CWA
THIS EVENING...AS AN UPPER LEVEL TROUGH PUSHES OUT OF THE NORTHERN
ROCKIES. PRECIPITATION IS EXPECTED TO BE PRIMARILY SNOW...BUT COULD
SEE SOME RAIN MIXED IN AT THE ONSET OF TAF ISSUANCE. MVFR VISIBILITY
WILL ACCOMPANY THE LIGHT SNOWFALL WHILE MVFR CEILINGS WILL BE
PREDOMINATE FOR MUCH OF THE AREA THIS EVENING WITH THE APPROACHING
MID LEVEL WAVE. BEST POTENTIAL FOR SNOWFALL AND BRIEF IFR CONDITIONS
WILL BE THROUGH THE MISSOURI RIVER CORRIDOR...INCLUDING KSUX WITH A
LOWER POTENTIAL WORKING NORTHWARD INTO THE I90 CORRIDOR AND KFSD.
DRIER AIR WILL START WORKING INTO THE AREA AROUND 06Z WITH LIFTING
CEILINGS LATE TONIGHT AND CLEARING SKIES FOR THURSDAY.
&&
.PREV DISCUSSION.../ISSUED AT 300 PM CST/
UPPER LEVEL LOW PRESSURE CONTINUES TO SAG SOUTH ACROSS THE ROCKIES
THIS AFTERNOON. A DECENT JET STREAK WILL SPREAD ACROSS THE NORTHERN
PLAINS...WHICH WILL INTERACT WITH A WEAK BOUNDARY IN THE MID LEVELS.
REALLY NOT MUCH LOW LEVEL MOISTURE AND INSTABILITY NOT PRESENT SO
ONLY EXPECTING MINOR AMOUNTS OF ACCUMULATION. THE BEST CHANCE TO GET
SOMETHING CLOSER TO A HALF AN INCH OR SO WILL BE ALONG THE MISSOURI
RIVER VALLEY INTO SOUTHERN NORTHWEST IOWA...WITH THE BEST CHANCE
EARLY THIS EVENING. DRIER AND COLDER AIR WILL WORK IN BEHIND THIS
SYSTEM WITH NORTH WINDS EXPECTED TO BE ABOUT 10 TO 20 MPH THROUGH
THE NIGHT INTO THURSDAY. DID LOWER LOWS JUST A TOUCH TONIGHT IN THE
FAR NORTH WHERE SOME CLEARING WILL BE POSSIBLE LATE...BUT REMAINED
CLOSEST TO THE CONSRAW OUTPUT WHICH TENDS TO PERFORM BETTER ON
WIND/CLOUDY NIGHTS.
CLOUDS WILL DECREASE FROM NORTH TO SOUTH THROUGH THE MORNING INTO
THE AFTERNOON ON THURSDAY AS WILL A BREEZY MORNING NORTHWEST WIND.
FAIRLY COLD 925MB TEMPERATURES FROM AROUND -6 TO -8 DEGREES C DO
SUPPORT HIGHS FROM NEAR 32 WEST TO THE UPPER 20S IN THE EAST...AND
WILL GO CLOSE TO THIS IN THE FORECAST. THIS COMES IN A COUPLE OF
DEGREES WARMER THAN THE CONSALL OUTPUT WHICH IS GOOD SINCE THE GEM
AND GFS...BOTH PART OF THE CONSALL...ARE TOO COLD AND HAVE BEEN
RUNNING A 3 TO 6 DEGREE COLD BIAS ON HIGHS FOR THE PAST 20 TO 30
DAYS. /08
FOR THE REST OF THE SHORTER RANGE...A MILD NORTHWEST FLOW ALOFT
REMAINS IN THIS AREA WITH THE SPLIT FLOW JET REGIME CONTINUING. WITH
THE UPPER FLOW COMING OUT OF SOUTHWEST CANADA...IT WILL BE A MILD
FLOW WITH SURFACE WINDS GENERALLY FROM A WESTERLY DIRECTION ALLOWING
FOR PRIME MIXING. GIVEN THE LATEST MODEL CONSENSUS OF 925MB
TEMPERATURES...SEE ABSOLUTELY NO REASON WHY GOING WITH THE WARMEST
GUIDANCE READINGS IS NOT A GOOD IDEA. THE LOW LYING LOCATIONS MAY
BOTTOM OUT A LITTLE THURSDAY NIGHT...BUT OTHERWISE BLENDING THE WARM
BIAS CORRECTED GUIDANCE READINGS WITH THE EVEN WARMER ECMWF NUMBERS
SEEMED PRUDENT.
IN THE EXTENDED SATURDAY NIGHT THROUGH WEDNESDAY...DRY WEATHER WILL
VERY LIKELY CONTINUE WITH THE SAME IDEA CONTINUING. THE 925MB
TEMPERATURES CONTINUE TO BE VERY WARM MEANING THAT GOING WITH THE
WARMEST GUIDANCE READINGS OF BIAS CORRECTED NUMBERS AND ECMWF VALUES
ARE PROBABLY THE BEST WAY TO GO. THE GFS AND GEM VALUES HAVE BEEN
RUNNING VERY COOL LATELY AND SHOULD BE DISCOUNTED.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
913 PM CST WED DEC 21 2011
.UPDATE...
RADAR SHOWS BACK EDGE OF PRECIPITATION GENERALLY ALONG A TELEGRAPH
TO QUEMADO LINE MOVING LITTLE. A WIDESPREAD AREA OF MOSTLY LIGHT
RAIN EXTENDS FROM THE MIDDLE RIO GRANDE PLAINS NORTHEAST TO
ENCOMPASS MUCH OF THE HILL COUNTRY AND ADJACENT PORTIONS OF SOUTH
CENTRAL TEXAS LATE THIS EVENING. THE NEW RUC SHORT TERM MODEL RUN
THIS EVENING SHOWS THE UPPER TROUGH PUSHING INTO FAR WESTERN
PORTIONS OF THE CWA (VAL VERDE COUNTY) SHORTLY AFTER MIDNIGHT...
THEN ACCELERATING EASTWARD OVERNIGHT AS IT WEAKENS. THE CURRENT
WIDESPREAD AREA OF LIGHT RAIN WILL CONTINUE TO SPREAD EAST AND BY
3 AM SHOULD ENCOMPASS ALL OF THE EASTERN HALF OF SOUTH CENTRAL
TEXAS WITH RAINS ENDING OVER THE HILL COUNTRY. RAINS SHOULD BE
ENDING OVER ALL OF THE AREA FROM THE WEST BY LATE MORNING. IT
SHOULD REMAIN LIGHT AND DUE TO THE WIDESPREAD AREA...ISOLATED
THUNDERSTORMS AT BEST ARE EXPECTED. GRIDS WERE READJUSTED ACCORDING
TO CURRENT RADAR AND SATELLITE TRENDS.
&&
.PREV DISCUSSION... /ISSUED 545 PM CST WED DEC 21 2011/
AVIATION...
VFR CONDITIONS WILL DETERIORATE QUICKLY AS UPPER LEVEL LOW IS
CURRENTLY GENERATING LIGHT RAIN...SHOWERS AND ISOLATED THUNDERSTORMS
ACROSS MEXICO AND ALONG THE RIO GRANDE. THIS PRECIPITATION WILL
SPREAD EAST AND NORTHEAST QUICKLY THROUGH 06Z. MVFR CEILINGS AND
RAIN WILL DEVELOP FROM WEST TO EAST THROUGH 05Z. THUNDERSTORMS ARE
POSSIBLE...MAINLY ALONG AND EAST OF I-35 BETWEEN 05Z-12Z. SMALL
HAIL WILL BE POSSIBLE WITH THE STRONGEST STORMS...BUT COVERAGE AND
PROBABILITIES ARE BOTH LOW...SO NOT MENTIONED IN THE TERMINAL
FORECAST. EXPECTED IMPROVEMENTS TO VFR CONDITIONS AFTER 13Z-15Z.
KDRT EXPECTED TO REMAIN VFR WITH LIGHT RAIN AND SHOWERS. WINDS ARE
EXPECTED TO BE VARIABLE IN DIRECTION...BUT LESS THAN 10 KNOTS
THROUGH THE FORECAST. FOR THE 30 HOUR TAF SITE...NEXT COLD FRONT
WILL CAUSE A WIND SHIFT TOWARDS THE END OF THE FORECAST PERIOD.
PREV DISCUSSION... /ISSUED 323 PM CST WED DEC 21 2011/
DISCUSSION...
A 500 HPA LOW NEAR THE BIG BEND CONTINUES TO DEVELOP AS IT MOVES
TO THE EAST. INCREASING CLOUDS CONTINUE OVER SOUTH CENTRAL TEXAS
EAST OF THIS WEATHER SYSTEM...AND THIS WILL CONTINUE THROUGH
TONIGHT. PATCHY AREAS OF LIGHT RAIN AND SHOWERS ARE DEVELOPING
FROM THE WEST...AND WILL MOVE OVER SOUTH CENTRAL TEXAS TONIGHT.
EXPECT OCCASIONAL RAIN OVER SOUTH CENTRAL TEXAS TONIGHT. RAINFALL
AMOUNTS NEAR A TENTH OF AN INCH ARE EXPECTED OVER THE WEST PART OF
THE AREA AND NEAR ONE HALF TO ONE INCH OVER THE EAST PART OF
SOUTH CENTRAL TEXAS TONIGHT. SHOWERS AND ISOLATED THUNDERSTORMS
ARE EXPECTED WITH THE RAIN TONIGHT. WINTER 2011/2012 WILL
OFFICIALLY BEGIN TONIGHT AT 1130 PM CST...AND WILL END AT 1214 AM
CDT ON TUESDAY...MARCH 20...2012...WHEN THE SPRING OF 2012
OFFICIALLY BEGINS.
ON THURSDAY...DECREASING CLOUDS AND RAIN CHANCES ARE STILL EXPECTED
FROM THE WEST IN THE MORNING...WITH A MOSTLY SUNNY TO PARTLY
CLOUDY CONDITIONS EXPECTED TO DEVELOP ON THURSDAY. WILL SHOW HIGHS
IN THE 60S OVER THE HILL COUNTRY AND IN THE UPPER 60S TO NEAR 70
OVER ADJACENT PARTS OF SOUTH CENTRAL TEXAS.
INCREASING CLOUDS ARE EXPECTED THURSDAY NIGHT AND FRIDAY...WITH
A CHANCE OF RAIN OR SHOWERS POSSIBLE FRIDAY NIGHT AND SATURDAY.
COLD CONDITIONS ARE EXPECTED WITH MOSTLY CLOUDY SKIES SATURDAY
AND SATURDAY NIGHT. RAIN CHANCES ARE EXPECTED TO DECREASE FROM THE
WEST SATURDAY NIGHT...FOLLOWED BY PARTLY CLOUDY CONDITIONS ON
SUNDAY...WITH DAYTIME HIGHS IN THE 50S.
A FAST MOVING DISTURBANCE WILL COME ACROSS SOUTH CENTRAL TEXAS
MONDAY...YET EXPECT SCATTERED CLOUDS WITH THIS WEATHER SYSTEM...
FOLLOWED BY MOSTLY SUNNY TO PARTLY CLOUDY CONDITIONS IN THE
DAY AND MOSTLY CLEAR NIGHTS ON TUESDAY AND WEDNESDAY OF NEXT
WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 42 67 42 52 36 / 80 20 - 10 20
AUSTIN BERGSTROM INTL AIRPORT 42 67 39 52 35 / 80 20 - 10 20
NEW BRAUNFELS MUNI AIRPORT 44 68 40 54 35 / 80 20 - 10 20
BURNET MUNI AIRPORT 41 65 38 49 34 / 60 10 - 10 10
DEL RIO INTL AIRPORT 39 66 38 51 35 / 50 - 0 - 20
GEORGETOWN MUNI AIRPORT 42 64 39 50 34 / 80 20 - 10 10
HONDO MUNI AIRPORT 44 70 39 55 36 / 70 10 - 10 30
SAN MARCOS MUNI AIRPORT 44 67 40 54 36 / 80 20 - 10 20
LA GRANGE - FAYETTE REGIONAL 47 66 45 56 39 / 80 40 10 10 20
SAN ANTONIO INTL AIRPORT 45 70 42 55 36 / 80 20 - 10 30
STINSON MUNI AIRPORT 46 70 44 56 38 / 80 20 - 10 30
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...10
SYNOPTIC/GRIDS...02
PUBLIC SERVICE/DATA COLLECTION...32
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1007 PM EST WED DEC 21 2011
.SYNOPSIS...
LOW PRESSURE WILL TRACK EASTWARD ACROSS NEW ENGLAND...DRAGGING A
WEAK COLD FRONT THROUGH THE AREA TONIGHT. THE FRONT WILL THEN
STALL ACROSS NORTHERN NORTH CAROLINA THURSDAY MORNING. A SERIES OF
LOW PRESSURE SYSTEMS WILL TRACK UP ALONG THE FRONT THURSDAY AND
AGAIN ON SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 1000 PM EDT WEDNESDAY...
SFC FRONT GETTING CLOSE TO WRN SLOPES OF APPALACHIANS BUT DRIER
LOW LEVEL AIR HAS MOVED INTO THE MTNS AND LIGHT SW WINDS HAVE KEPT
FOG AND DRIZZLE FROM DEVELOPING. ALL PRECIP HAS MOVED EAST OF FCST
AREA AS WELL. SOME LIGHT SOUTHEAST SFC FLOW ON EAST SIDE OF BLUE
RIDGE IS KEEPING LOW CLOUDS AND FOG BANKED UP AGAINST BLUE RIDGE
IN FAR NW NC INCLUDING FANCY GAP...BUT AS FLOW BEGINS TO TURN MORE
SW AND THEN WEST BEHIND FRONT LATER TONIGHT THIS SHOULD LIFT. AT
THE SAME TIME...COOLER AIR BEHIND FRONT AND LIONGERING LOW LEVEL
MSTR ON GROUND...AND WITH POTENTIAL FOR THINNING OUT OF HIGH
CLOUDS...COULD RESULT IN SOME PATCHY VALLEY FOG. ENDED UP REMOVING
MUCH OF THE PATCHY DRIZZLE FROM PREVIOUS UPDATE...AND REDUCING
AREAS OF FOG...EXCEPT FOR MTN VALLEYS AND CLOSER TO WHERE SFC
FRONTAL POSITION IS EXPECTED TO STALL TOWARD MORNING ACROSS FAR
SOUTHEAST. LEFT A SLIGHT CHC OF A SHOWER DOWN THERE AS WELL.
OVERNIGHT TEMPS ARE TRICKY AS AIR BEHIND FRONT IS COOLER BUT NOT
THAT COOL...AND OVERALL THIS HAS BEEN SLOWING DOWN. ENDED UP
BOOSTING OVERNIGHT MINS A COUPLE DEG BECAUSE OF SLOWER
MOVEMENT...AND NOT DROPPING DEW PTS OFF QUITE AS FAST...BUT STILL
FALLING. ALSO MADE SOME MINOR CHANGES INTO THURSDAY MORNING PER
SLOWER MODEL SOLUTIONS FOR NEXT WAVE MOVING UP ALONG FRONT. RAIN
MAY NOT REACH FAR SW UNTIL MIDDAY...AND THEN PERHAPS NOT UNTIL LATE
AFTERNOON OR EARLY EVENING ACROSS THE NORTHEAST. MID SHIFT MAY
NEED TO SLOW THIS DOWN EVEN MORE.
AS OF 710 PM EST WEDNESDAY...
LIGHT SHOWERS AHEAD OF WEAK FRONT HAVE FADED QUICKLY THIS EVENING
AND ONLY A FEW SPOTTY SHOWERS REMAIN...PRIMARILY EAST OF THE BLUE
RIDGE. HAVE UPDATED POPS ACCORDINGLY. LINGERING LOW LEVEL MSTR
WITH STEADY WINDS ALONG THE RIDGES MAY STILL RESULT IN ENOUGH
SHALLOW LIFT FOR SOME DRIZZLE AS WELL AS PATCHY FOG...SUCH AS
ALONG AND NEAR THE BLUE RIDGE AND HOT SPRINGS VCNTY. MID CLOUDS
THINNING OUT AND WITH PARTIAL CLEARING...COULD BEGIN TO SEE SOME
PATCHY FOG IN VALLEYS AS WELL AS WINDS REMAIN DECOUPLED THERE...SO
HAVE INCLUDED A FAIRLY WIDESPREAD AREA OF PATCHY FOG...WITH AREAS
OF FOG ALONG THE BLUE RIDGE. REMOVED MENTION OF ANY DRIZZLE AFTER
MIDNIGHT AS SHALLOW MOISTURE BEGINS TO DRY OUT SLIGHTLY...BUT WILL
KEEP FOG IN THROUGH OVERNIGHT FOR NOW. ALSO WILL KEEP SLIGHT CHC
SHWRS NEAR WEAK FRONTAL BOUNDARY POSITION LATE TONIGHT OUT IN FAR
SOUTHEAT PIEDMONT...AS SUGGESTED BY LOCAL WRF AND HRRR MODELS.
PREV DISCUSSION AS OF 318 PM EST WEDNESDAY...
A WEAK COLD FRONT WILL PIVOT OVER THE AREA TONIGHT...THEN STALL
ACROSS NORTHERN NORTH CAROLINA. THE RAIN WILL END WEST TO EAST THIS
EVENING. AREAS OF DRIZZLE POSSIBLE ON WESTERN FACING SLOPES AND NEAR
THE FRONT THROUGH EARLY MORNING. CLOUD COVER SHOULD ALSO LINGER WITH
THE FRONT STALLED IN THE VICINITY. SOME CLEARING IS POSSIBLE OVER
THE GREENBRIER VALLEY AND ALLEGHANY HIGHLANDS TONIGHT AS HIGH
PRESSURE TRACKS EASTWARD. IF CLEARING IS PRONOUNCED ENOUGH...PATCHY
DENSE FOG COULD DEVELOP TOWARD SUNRISE.
MARITIME AIR BEHIND THE FRONT WILL KEEP TEMPERATURES MILD AND ABOVE
NORMAL.
WINTER SOLSTICE TO BEGIN TONIGHT AT 530Z/1230 AM.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
AS OF 320 PM EST WEDNESDAY...
NEXT IN SERIES OF SOUTHERN STREAM SHORT WAVES EXPECTED TO LIFT
NORTHEAST OUT OF THE SOUTHERN PLAINS AND GULF COAST STATES INTO THE
MID APPALACHIAN AND MID ATLANTIC STATES THURSDAY INTO THURSDAY
NIGHT...TO BE FOLLOWED BY SLIGHTLY COOLER AND DRIER AIR ON THE
BACKSIDE OF THE SYSTEM LATER THURSDAY NIGHT INTO SATURDAY.
ABUNDANT MID AND HIGH LEVEL CLOUDS STREAMING NORTHEAST IN ADVANCE OF
THE SYSTEM SHOULD ASSURE A MOSTLY CLOUDY TO CLOUDY START IN MOST
LOCATIONS ON THURSDAY...WITH THREAT OF PRECIPITATION INCREASING AS
THE DAY PROGRESSES FROM SOUTH TO NORTH AS BROAD UPWARD VERTICAL
MOTIONS FIELDS FROM STRONG MOISTURE TRANSPORT AND INCREASING
ISENTROPIC LIFT IN 850-600 MILLIBAR LAYER COMBINE WITH DIFFERENTIAL
POSITIVE VORTICITY ADVECTION AND UPPER DILUENT FIELD WITH APPROACH
OF RIGHT ENTRANCE REGION OF UPPER JET MAX. EXPECT TO SEE A GOOD
DRENCHING RAIN THROUGHOUT THE ENTIRE BLACKSBURG FORECAST AREA BY
DAYS END...CONTINUING THROUGH THE EVENING HOURS BEFORE BEGINNING TO
TAPER OFF FROM WITH WEST DURING THE EARNING MORNING HOURS ON FRIDAY
WITH PASSAGE OF COOL FRONT. AT THE PRESENT TIME...TOTAL RAINFALL
AMOUNTS FROM THIS SYSTEM ARE NOT EXPECTED TO BE EXCESSIVE...
GENERALLY IN THE ONE-HALF TO ONE-INCH RANGE.
DOWNSLOPING WINDS EAST OF THE BLUE RIDGE SHOULD ALLOW FOR DRY AND
MILD WEATHER ACROSS THE PIEDMONT FRIDAY INTO SATURDAY...ALTHOUGH
SOUTHWESTERLY FLOW ALOFT WILL MAINTAIN AT LEAST SOME PARTIAL MID AND
HIGH LEVEL CLOUD COVER. WEST OF THE BLUE RIDGE...COOL ADVECTION
UPSLOPING WINDS SHOULD MAINTAIN LOWER LEVEL CLOUDS FOR MUCH OF THE
PERIOD...WITH PERHAPS EVEN SOME SPOTTY SHOWERS OR FLURRIES ACROSS
THE PREFERRED HIGHER WEST FACING SLOPES INTO FRIDAY NIGHT.
MOS GUIDANCE THROUGH THE PERIOD QUITE CONSISTENT AND GENERALLY
ACCEPTED EXCLUDING NEED TO SUBTLY TWEAK SOME TEMPERATURES TO REFLECT
LOCAL CLIMATOLOGICAL INFLUENCES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 330 PM EST WEDNESDAY...
COMPLICATED WEATHER PATTERN IN THE LONG TERM. FORECAST IS HEAVILY
DEPENDENT ON THE EVOLUTION OF A CLOSED UPPER LEVEL LOW THAT IS
CURRENTLY DROPPING INTO THE SOUTHWESTERN PART OF THE COUNTRY. HOW
QUICKLY AND HOW MUCH OF THIS ENERGY EJECTS NORTHEAST WILL PLAY A
MAJOR FACTOR IN OUR WEATHER CHRISTMAS DAY INTO EARLY NEXT WEEK. THE
STRENGTH OF A NORTHERN STREAM WAVE FORECAST TO MOVE INTO THE
NORTHEAST WILL ALSO PLAY A BIG ROLE.
ECMWF AND GFS CONTINUE TO EJECT SOME OF THE ENERGY OVER THE
SOUTHWESTERN STATES INTO OUR REGION CHRISTMAS DAY. HOWEVER THE
AMOUNT OF ENERGY EJECTED CONTINUES TO TREND DOWN...AND THE 12Z GFS
ENSEMBLES HAVE ALSO TRENDED DRY ON CHRISTMAS DAY. MODELS ARE ALSO
TRENDING STRONGER WITH THE NORTHERN STREAM ENERGY...WHICH WOULD
EFFECTIVELY PUSH ANY WAVE FURTHER SOUTH ON CHRISTMAS DAY. BUT JUST
HOW MUCH THIS NORTHERN STREAM CAN SUPPRESS THE SOUTHEAST RIDGE IS
STILL IN QUESTION. GIVEN THE PERSISTENCE OF THE SOUTHEAST RIDGE THIS
MONTH...NOT READY TO GO COMPLETELY WITH THE SOUTHERN SOLUTION. BUT
GIVEN LATEST ECMWF TREND OF PUSHING THE WAVE SOUTH...AND 12Z GFS
ENSEMBLE MEAN KEEPING US DRY...HAVE TRENDED TOWARD THE SOUTHERN
SOLUTION. THIS WOULD KEEP THE BEST CHANCE OF RAIN NEAR THE NC/VA
BORDER AND POINTS SOUTH...WITH DECREASING CHANCES TO THE NORTH.
ENOUGH COLD AIR MAY BE PRESENT FOR SOME SNOW ON THE FAR NORTHERN
FRINGE OF THE PRECIP SHIELD NORTH OF ROUTE 460...HOWEVER THIS IS
STILL A LOW PROBABILITY EVENT AND NO ACCUMULATIONS EXPECTED AT THIS
TIME.
EXPECT A BRIEF DRY PERIOD AND SHOT OF COLD AIR BEHIND THIS SYSTEM ON
MONDAY. HOWEVER MODEL DIFFERENCES BEGIN TO INCREASE AGAIN BY
TUESDAY. THE REST OF THE ENERGY ASSOCIATED WITH THE CLOSED SOUTHWEST
LOW SHOULD FINALLY EJECT NORTHEASTWARD MONDAY NIGHT INTO TUESDAY.
LAST 2 RUNS OF THE ECMWF AND ABOUT HALF THE GFS ENSEMBLES PUSH THIS
WAVE TO OUR NORTH TUESDAY AND TUESDAY NIGHT BRINGING MORE RAIN TO
THE REGION. GIVEN THE CONSISTENCY OF THE ECMWF SOLUTION...AND THE GFS
ENSEMBLES COMING ON BOARD...HAVE TRENDED THE FORECAST TOWARDS THIS
SOLUTION. ECMWF HAS SOME LOW LEVEL COLD AIR LOCKED IN AHEAD OF THIS
SYSTEM...SO VERBATIM IT WOULD HAVE SOME SLEET OR FREEZING RAIN IN
THE ALLEGHANY HIGHLANDS. HOWEVER THIS IS A LOW PROBABILITY
EVENT...BUT WILL BE MONITORED IN THE COMING DAYS.
WENT CLOSE TO HPC GUIDANCE...TRENDED A BIT TOWARD THE ECMWF...FOR
TEMPERATURES THIS PERIOD. THIS RESULTS IN TEMPERATURES AROUND
AVERAGE...HIGHS GENERALLY IN THE 40S WEST AND AROUND 50 EAST...AND
LOWS IN THE 20S TO AROUND 30. COLDEST DAYS LOOK TO BE MONDAY BEHIND
THE FIRST SYSTEM...AND THEN AGAIN ON WEDNESDAY BEHIND THE POTENTIAL
SECOND SYSTEM.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
AS OF 715 PM EST WEDNESDAY...
FRONT JUST ENTERING THE WESTERN PART OF THE CWA AROUND 7PM AND WILL
CONTINUE TO SLOWLY PUSH EAST THROUGH THE NIGHT. CONDITIONS HAVE
BECOME VFR AT BLF...LWB...BCB AS THE RAIN HAS PUSHED OFF TO THE
EAST. TOUGH FORECAST TONIGHT WITH RATHER LOW CONFIDENCE...BUT
BELIEVE THAT MVFR CEILINGS WILL MOVE BACK INTO AT LEAST BLF AND BCB
LATER THIS EVENING AS COLDER LOW LEVEL AIR MOVES IN AND SATURATES
THE LOW LEVELS. MAY EVEN DROP DOWN TO IFR AT BLF AFTER MIDNIGHT. AT
LWB EXPECT THE CLEARING TO ALLOW FOG TO FORM AND POSSIBLY BECOME
VLIFR DENSE AFTER MIDNIGHT.
LYNCHBURG AND DANVILLE WILL REMAIN ON THE WARM SIDE OF THE FRONT
THROUGH MUCH OF THE NIGHT...AND EXPECT MVFR CEILINGS TO LINGER
THROUGH THE NIGHT. AS TEMPERATURES COOL A BIT AFTER MIDNIGHT...AND
LOW LEVEL MOISTURE REMAINS...EXPECT DAN TO DROP TO IFR CEILINGS FOR
A FEW HOURS. BOTH SHOULD ALSO EXPERIENCE SOME FOG AS WE GO THROUGH
THE NIGHT...BUT NOT AS DENSE AS OUT WEST AS THE CLOUD COVER SHOULD
REMAIN THICKER. IF LYNCHBURG CAN BREAK OUT AFTER THE FRONT PASSES
TOWARDS MORNING...MAY SEE SOME IFR FOG THERE FOR A FEW HOURS. EXPECT
ROA TO REMAIN MAINLY VFR THOUGH THE NIGHT...WITH POSSIBLY A FEW
HOURS OF IFR CEILINGS AS THE SLIGHTLY COOLER AIR MOVES IN.
THE FRONT STALLS ALONG THE VIRGINIA-NORTH CAROLINA BORDER TONIGHT
THEN ANOTHER LOW PRESSURE SYSTEM TRACKS ALONG THE FRONT BY THURSDAY
NIGHT. MOST TAF SITES SHOULD BE ABLE TO BREAK OUT OF THE LOW CLOUDS
FOR A PERIOD THURSDAY LATE MORNING AND AFTERNOON...WITH THE
EXCEPTION OF PLACES CLOSER TO THE FRONT...SUCH AS DAN. HOWEVER THE
NEXT WAVE QUICKLY APPROACHES BY 5PM...BRINGING MORE RAIN AND REDUCED
CEILINGS.
THIS CLEARS OUT BY FRIDAY...WITH VFR CONDITIONS EXPECTED IN THE
EAST...AND POSSIBLY MVFR UPSLOPE CLOUDS IN THE MOUNTAINS. EVERYONE
SHOULD BECOME VFR BY SATURDAY AS HIGH PRESSURE BUILDS IN. A STORM
MAY BRING ANOTHER ROUND OF RAIN SUNDAY...ALTHOUGH MODELS HAVE BEEN
TRENDING FURTHER SOUTH WITH THIS STORM. THUS BEST CHANCE OF RAIN AND
REDUCED CEILINGS APPEARS TO BE CLOSER TO THE NC/VA BORDER IF
ANYWHERE.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...RCS/SK
NEAR TERM...RCS/SK
SHORT TERM...WERT
LONG TERM...MC
AVIATION...MC/RCS
AREA FORECAST DISCUSSION...CORRECTED FOR MISSING PARAGRAPHS
NWS BLACKSBURG VA
715 PM EST WED DEC 21 2011
.SYNOPSIS...
LOW PRESSURE WILL TRACK EASTWARD ACROSS NEW ENGLAND...DRAGGING A
WEAK COLD FRONT THROUGH THE AREA TONIGHT. THE FRONT WILL THEN
STALL ACROSS NORTHERN NORTH CAROLINA THURSDAY MORNING. A SERIES OF
LOW PRESSURE SYSTEMS WILL TRACK UP ALONG THE FRONT THURSDAY AND
AGAIN ON SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 710 PM EST WEDNESDAY...
LIGHT SHOWERS AHEAD OF WEAK FRONT HAVE FADED QUICKLY THIS EVENING
AND ONLY A FEW SPOTTY SHOWERS REMAIN...PRIMARILY EAST OF THE BLUE
RIDGE. HAVE UPDATED POPS ACCORDINGLY. LINGERING LOW LEVEL MSTR
WITH STEADY WINDS ALONG THE RIDGES MAY STILL RESULT IN ENOUGH
SHALLOW LIFT FOR SOME DRIZZLE AS WELL AS PATCHY FOG...SUCH AS
ALONG AND NEAR THE BLUE RIDGE AND HOT SPRINGS VCNTY. MID CLOUDS
THINNING OUT AND WITH PARTIAL CLEARING...COULD BEGIN TO SEE SOME
PATCHY FOG IN VALLEYS AS WELL AS WINDS REMAIN DECOUPLED THERE...SO
HAVE INCLUDED A FAIRLY WIDESPREAD AREA OF PATCHY FOG...WITH AREAS
OF FOG ALONG THE BLUE RIDGE. REMOVED MENTION OF ANY DRIZZLE AFTER
MIDNIGHT AS SHALLOW MOISTURE BEGINS TO DRY OUT SLIGHTLY...BUT WILL
KEEP FOG IN THROUGH OVERNIGHT FOR NOW. ALSO WILL KEEP SLIGHT CHC
SHWRS NEAR WEAK FRONTAL BOUNDARY POSITION LATE TONIGHT OUT IN FAR
SOUTHEAT PIEDMONT...AS SUGGESTED BY LOCAL WRF AND HRRR MODELS.
PREV DISCUSSION AS OF 318 PM EST WEDNESDAY...
A WEAK COLD FRONT WILL PIVOT OVER THE AREA TONIGHT...THEN STALL
ACROSS NORTHERN NORTH CAROLINA. THE RAIN WILL END WEST TO EAST THIS
EVENING. AREAS OF DRIZZLE POSSIBLE ON WESTERN FACING SLOPES AND NEAR
THE FRONT THROUGH EARLY MORNING. CLOUD COVER SHOULD ALSO LINGER WITH
THE FRONT STALLED IN THE VICINITY. SOME CLEARING IS POSSIBLE OVER
THE GREENBRIER VALLEY AND ALLEGHANY HIGHLANDS TONIGHT AS HIGH
PRESSURE TRACKS EASTWARD. IF CLEARING IS PRONOUNCED ENOUGH...PATCHY
DENSE FOG COULD DEVELOP TOWARD SUNRISE.
MARITIME AIR BEHIND THE FRONT WILL KEEP TEMPERATURES MILD AND ABOVE
NORMAL.
WINTER SOLSTICE TO BEGIN TONIGHT AT 530Z/1230 AM.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
AS OF 320 PM EST WEDNESDAY...
NEXT IN SERIES OF SOUTHERN STREAM SHORT WAVES EXPECTED TO LIFT
NORTHEAST OUT OF THE SOUTHERN PLAINS AND GULF COAST STATES INTO THE
MID APPALACHIAN AND MID ATLANTIC STATES THURSDAY INTO THURSDAY
NIGHT...TO BE FOLLOWED BY SLIGHTLY COOLER AND DRIER AIR ON THE
BACKSIDE OF THE SYSTEM LATER THURSDAY NIGHT INTO SATURDAY.
ABUNDANT MID AND HIGH LEVEL CLOUDS STREAMING NORTHEAST IN ADVANCE OF
THE SYSTEM SHOULD ASSURE A MOSTLY CLOUDY TO CLOUDY START IN MOST
LOCATIONS ON THURSDAY...WITH THREAT OF PRECIPITATION INCREASING AS
THE DAY PROGRESSES FROM SOUTH TO NORTH AS BROAD UPWARD VERTICAL
MOTIONS FIELDS FROM STRONG MOISTURE TRANSPORT AND INCREASING
ISENTROPIC LIFT IN 850-600 MILLIBAR LAYER COMBINE WITH DIFFERENTIAL
POSITIVE VORTICITY ADVECTION AND UPPER DILUENT FIELD WITH APPROACH
OF RIGHT ENTRANCE REGION OF UPPER JET MAX. EXPECT TO SEE A GOOD
DRENCHING RAIN THROUGHOUT THE ENTIRE BLACKSBURG FORECAST AREA BY
DAYS END...CONTINUING THROUGH THE EVENING HOURS BEFORE BEGINNING TO
TAPER OFF FROM WITH WEST DURING THE EARNING MORNING HOURS ON FRIDAY
WITH PASSAGE OF COOL FRONT. AT THE PRESENT TIME...TOTAL RAINFALL
AMOUNTS FROM THIS SYSTEM ARE NOT EXPECTED TO BE EXCESSIVE...
GENERALLY IN THE ONE-HALF TO ONE-INCH RANGE.
DOWNSLOPING WINDS EAST OF THE BLUE RIDGE SHOULD ALLOW FOR DRY AND
MILD WEATHER ACROSS THE PIEDMONT FRIDAY INTO SATURDAY...ALTHOUGH
SOUTHWESTERLY FLOW ALOFT WILL MAINTAIN AT LEAST SOME PARTIAL MID AND
HIGH LEVEL CLOUD COVER. WEST OF THE BLUE RIDGE...COOL ADVECTION
UPSLOPING WINDS SHOULD MAINTAIN LOWER LEVEL CLOUDS FOR MUCH OF THE
PERIOD...WITH PERHAPS EVEN SOME SPOTTY SHOWERS OR FLURRIES ACROSS
THE PREFERRED HIGHER WEST FACING SLOPES INTO FRIDAY NIGHT.
MOS GUIDANCE THROUGH THE PERIOD QUITE CONSISTENT AND GENERALLY
ACCEPTED EXCLUDING NEED TO SUBTLY TWEAK SOME TEMPERATURES TO REFLECT
LOCAL CLIMATOLOGICAL INFLUENCES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 330 PM EST WEDNESDAY...
COMPLICATED WEATHER PATTERN IN THE LONG TERM. FORECAST IS HEAVILY
DEPENDENT ON THE EVOLUTION OF A CLOSED UPPER LEVEL LOW THAT IS
CURRENTLY DROPPING INTO THE SOUTHWESTERN PART OF THE COUNTRY. HOW
QUICKLY AND HOW MUCH OF THIS ENERGY EJECTS NORTHEAST WILL PLAY A
MAJOR FACTOR IN OUR WEATHER CHRISTMAS DAY INTO EARLY NEXT WEEK. THE
STRENGTH OF A NORTHERN STREAM WAVE FORECAST TO MOVE INTO THE
NORTHEAST WILL ALSO PLAY A BIG ROLE.
ECMWF AND GFS CONTINUE TO EJECT SOME OF THE ENERGY OVER THE
SOUTHWESTERN STATES INTO OUR REGION CHRISTMAS DAY. HOWEVER THE
AMOUNT OF ENERGY EJECTED CONTINUES TO TREND DOWN...AND THE 12Z GFS
ENSEMBLES HAVE ALSO TRENDED DRY ON CHRISTMAS DAY. MODELS ARE ALSO
TRENDING STRONGER WITH THE NORTHERN STREAM ENERGY...WHICH WOULD
EFFECTIVELY PUSH ANY WAVE FURTHER SOUTH ON CHRISTMAS DAY. BUT JUST
HOW MUCH THIS NORTHERN STREAM CAN SUPPRESS THE SOUTHEAST RIDGE IS
STILL IN QUESTION. GIVEN THE PERSISTENCE OF THE SOUTHEAST RIDGE THIS
MONTH...NOT READY TO GO COMPLETELY WITH THE SOUTHERN SOLUTION. BUT
GIVEN LATEST ECMWF TREND OF PUSHING THE WAVE SOUTH...AND 12Z GFS
ENSEMBLE MEAN KEEPING US DRY...HAVE TRENDED TOWARD THE SOUTHERN
SOLUTION. THIS WOULD KEEP THE BEST CHANCE OF RAIN NEAR THE NC/VA
BORDER AND POINTS SOUTH...WITH DECREASING CHANCES TO THE NORTH.
ENOUGH COLD AIR MAY BE PRESENT FOR SOME SNOW ON THE FAR NORTHERN
FRINGE OF THE PRECIP SHIELD NORTH OF ROUTE 460...HOWEVER THIS IS
STILL A LOW PROBABILITY EVENT AND NO ACCUMULATIONS EXPECTED AT THIS
TIME.
EXPECT A BRIEF DRY PERIOD AND SHOT OF COLD AIR BEHIND THIS SYSTEM ON
MONDAY. HOWEVER MODEL DIFFERENCES BEGIN TO INCREASE AGAIN BY
TUESDAY. THE REST OF THE ENERGY ASSOCIATED WITH THE CLOSED SOUTHWEST
LOW SHOULD FINALLY EJECT NORTHEASTWARD MONDAY NIGHT INTO TUESDAY.
LAST 2 RUNS OF THE ECMWF AND ABOUT HALF THE GFS ENSEMBLES PUSH THIS
WAVE TO OUR NORTH TUESDAY AND TUESDAY NIGHT BRINGING MORE RAIN TO
THE REGION. GIVEN THE CONSISTENCY OF THE ECMWF SOLUTION...AND THE GFS
ENSEMBLES COMING ON BOARD...HAVE TRENDED THE FORECAST TOWARDS THIS
SOLUTION. ECMWF HAS SOME LOW LEVEL COLD AIR LOCKED IN AHEAD OF THIS
SYSTEM...SO VERBATIM IT WOULD HAVE SOME SLEET OR FREEZING RAIN IN
THE ALLEGHANY HIGHLANDS. HOWEVER THIS IS A LOW PROBABILITY
EVENT...BUT WILL BE MONITORED IN THE COMING DAYS.
WENT CLOSE TO HPC GUIDANCE...TRENDED A BIT TOWARD THE ECMWF...FOR
TEMPERATURES THIS PERIOD. THIS RESULTS IN TEMPERATURES AROUND
AVERAGE...HIGHS GENERALLY IN THE 40S WEST AND AROUND 50 EAST...AND
LOWS IN THE 20S TO AROUND 30. COLDEST DAYS LOOK TO BE MONDAY BEHIND
THE FIRST SYSTEM...AND THEN AGAIN ON WEDNESDAY BEHIND THE POTENTIAL
SECOND SYSTEM.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 715 PM EST WEDNESDAY...
FRONT JUST ENTERING THE WESTERN PART OF THE CWA AROUND 7PM AND WILL
CONTINUE TO SLOWLY PUSH EAST THROUGH THE NIGHT. CONDITIONS HAVE
BECOME VFR AT BLF...LWB...BCB AS THE RAIN HAS PUSHED OFF TO THE
EAST. TOUGH FORECAST TONIGHT WITH RATHER LOW CONFIDENCE...BUT
BELIEVE THAT MVFR CEILINGS WILL MOVE BACK INTO AT LEAST BLF AND BCB
LATER THIS EVENING AS COLDER LOW LEVEL AIR MOVES IN AND SATURATES
THE LOW LEVELS. MAY EVEN DROP DOWN TO IFR AT BLF AFTER MIDNIGHT. AT
LWB EXPECT THE CLEARING TO ALLOW FOG TO FORM AND POSSIBLY BECOME
VLIFR DENSE AFTER MIDNIGHT.
LYNCHBURG AND DANVILLE WILL REMAIN ON THE WARM SIDE OF THE FRONT
THROUGH MUCH OF THE NIGHT...AND EXPECT MVFR CEILINGS TO LINGER
THROUGH THE NIGHT. AS TEMPERATURES COOL A BIT AFTER MIDNIGHT...AND
LOW LEVEL MOISTURE REMAINS...EXPECT DAN TO DROP TO IFR CEILINGS FOR
A FEW HOURS. BOTH SHOULD ALSO EXPERIENCE SOME FOG AS WE GO THROUGH
THE NIGHT...BUT NOT AS DENSE AS OUT WEST AS THE CLOUD COVER SHOULD
REMAIN THICKER. IF LYNCHBURG CAN BREAK OUT AFTER THE FRONT PASSES
TOWARDS MORNING...MAY SEE SOME IFR FOG THERE FOR A FEW HOURS. EXPECT
ROA TO REMAIN MAINLY VFR THOUGH THE NIGHT...WITH POSSIBLY A FEW
HOURS OF IFR CEILINGS AS THE SLIGHTLY COOLER AIR MOVES IN.
THE FRONT STALLS ALONG THE VIRGINIA-NORTH CAROLINA BORDER TONIGHT
THEN ANOTHER LOW PRESSURE SYSTEM TRACKS ALONG THE FRONT BY THURSDAY
NIGHT. MOST TAF SITES SHOULD BE ABLE TO BREAK OUT OF THE LOW CLOUDS
FOR A PERIOD THURSDAY LATE MORNING AND AFTERNOON...WITH THE
EXCEPTION OF PLACES CLOSER TO THE FRONT...SUCH AS DAN. HOWEVER THE
NEXT WAVE QUICKLY APPROACHES BY 5PM...BRINGING MORE RAIN AND REDUCED
CEILINGS.
THIS CLEARS OUT BY FRIDAY...WITH VFR CONDITIONS EXPECTED IN THE
EAST...AND POSSIBLY MVFR UPSLOPE CLOUDS IN THE MOUNTAINS. EVERYONE
SHOULD BECOME VFR BY SATURDAY AS HIGH PRESSURE BUILDS IN. A STORM
MAY BRING ANOTHER ROUND OF RAIN SUNDAY...ALTHOUGH MODELS HAVE BEEN
TRENDING FURTHER SOUTH WITH THIS STORM. THUS BEST CHANCE OF RAIN AND
REDUCED CEILINGS APPEARS TO BE CLOSER TO THE NC/VA BORDER IF
ANYWHERE.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...RCS/SK
NEAR TERM...RCS/SK
SHORT TERM...WERT
LONG TERM...MC
AVIATION...MC/RCS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1157 PM EST MON DEC 19 2011
.SYNOPSIS...
A FRONTAL BOUNDARY WILL STALL OUT NORTH OF THE AREA TONIGHT AND
TUESDAY WITH A MILD SOUTHWEST FLOW TO PREDOMINATE. MEANWHILE
STRONG LOW PRESSURE WILL LIFT WELL TO THE NORTHWEST OF THE REGION ON
TUESDAY NIGHT WITH ITS ASSOCIATED COLD FRONT WORKING EAST THROUGH
THE AREA ON WEDNESDAY. AN AREA OF LOW PRESSURE WILL TRACK THROUGH
THE CAROLINAS AND VIRGINIA ON FRIDAY. STRONG UPPER LEVEL HIGH
PRESSURE WILL HOLD BACK ANY INTRUSIONS OF COLDER AIR UNTIL LATE
WEEKEND OR EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 955 PM EST MONDAY...
STILL APPEARS THAT MOST OF THE WARM FRONTAL SHWOERY PRECIP WILL
REMAIN TO THE NORTHWEST OF THE BLACKSBURG FORECAST AREA
OVERNIGHT...HOWEVER ONLY ONE MODEL...LAST FEW RUNS OF THE HOURLY
HRRR...SHOWS ANY INDICATION OF THE ISOLATED SHOWERS LIFTING INTO
EASTERN KY FROM SOUTHERN KY...AND THOSE STAND A MUCH BETTER CHANCE
OF REACHING INTO WRN GREENBRIER OR EVEN SUMMERS COUNTIES A LITTLE
AFTER MIDNIGHT...SO LEANED TOWARD HRRR SOLUTION FOR THAT AND
SLIGHTLY INCREASED THE AREA OF CHC POPS AS WELL AS SLIGHT CHC
POPS. WITH HARDLY ANY BREAKS IN CLOUD COVER EXPECTED ACROSS THE
WEST...AM EXPECTING OVERNIGHT TEMPS TO REMAIN AT OR ABOVE
FREEZING AND SO NOW ONLY HAVE ONE OR TWO GRID POINTS IN GREENBRIER
SUGGESTING ANY SNOW MIXED IN WITH RAIN. ANY PRECIP WILL BE BARELY
MORE THAN A SPRINKLE ANYWAY.
18Z MODEL TRENDS ARE TO SLOW DOWN ANY THREAT OF EVEN LIGHT UPSLOPE
DRIZZLE ALONG THE SOUTHERN BLUE RIDGE UNTIL TOMORROW EVENING AS
MOIST SW FLOW INCREASED AHEAD OF APPROACHING MIDWEST SYSTEM...AND
THE SLOWER TIMING HAS BEEN A CONSISTENT TREND IN MODELS SO MAY BE
PRUDENT TO CONSIDER REMOVING ANY POPS DURING THE DAY TUES.
PREV UPDATE AS OF 710 PM EST MONDAY...
VERY MINOR UPDATE TO INCLUDE MENTION OF SLIGHT CHANCE SHWRS FROM
NOW THROUGH REST OF OVERNIGHT PER RADAR SHOWING WHAT MAY BE A FEW
SPRINKLES OVER THE HIGHER ELEVATIONS OF GREENBRIER AND MAYBE
REACHING PARTS OF BATH COUNTY SOON. STILL LOOKS LIKE ANY AREAS OF
STEADIER LGITH RAIN ASSOC WITH WAVE ALONG WARM FRONT WILL REMAIN
TO THE NORTH OF THE FCST AREA LATER ON TONIGHT...BUT AM KEEPING
THE TINY CORNER OF CHC POPS IN CLOSER TO 12Z. FCST SOUNDINGS
INDICATE NO CHC FOR FREEZING RAIN...MORE LIKELY A SNOW FLAKE THAT
SURVIVES BY WET BULBING THROUGH A PRETTY DRY LOWER ATMOS...SO
REMOVED FREEZING RAIN GRIDS AND INCLUDED A FEW SNOW OR SNOW MIXED
WITH RAIN...AGAIN ONLY A SLIGHT CHC. OTHERWISE MADE A FEW TWEAKS
TO SKTY COVER AND LATEST TEMPS AND DEW PTS...WITH SOME LOWER TEENS
DEW PTS AT SOME HIGHER ELEVATIONS. INCREASED WIND GUSTS ALONG SOME
OF THE RIDGES TO BETTER MATCH SOME RECENT OBS AT HSP.
PREV DISCUSSION AS OF 255 PM EST MONDAY...
RIBBON OF HIGHER MOISTURE/PRECIP FORECAST TO STREAM EASTWARD ALONG A
FRONTAL BOUNDARY EMANATING FROM THE STRONG LOW NOW BRINGING
EXTREME WINTER CONDITIONS TO PARTS OF THE SOUTHWESTERN U.S. HIGHER
RH WITH VERY LIGHT PRECIP COULD FLIRT WITH OUR FAR NORTHERN ZONES
AROUND 09-12Z BUT MODELS CONTINUE TO HOLD THE BULK OF COLD AIR
JUST TO THE NORTH OF THE CWA. H85 REMAINS JUST ABV 0C AND VARIOUS
MODEL P-TYPE ALGORITHMS AND THICKNESS PARAMETERS ALSO KEEP FROZEN
VARIETY JUST NORTH. THAT IS ASSUMING ANY PRECIP AT ALL MAKES IT
INTO THE CWA AND WHATEVER DOES FALL LOOKS TO BE VERY LIGHT.STILL
PLENTY OF DRY AIR OT OVERCOME AS 12Z RNK SOUNDING SHOWED PWAT OF
ONLY 0.24 INCHES OR ABOUT HALF OF NORMAL. SREF PROB AND ENSEMBLE
MEANS BRING VERY LITTLE IF ANY MEASURABLE TO FAR NORTHERN ZONES
EARLY IN THE MORNING. LEFT A FEW HOURS OF SLIGHT CHANCE POPS IN
THE GRIDS OVER GREENBRIER AND BATH COUNTIES WITH POCKETS OF MIXED
PCPN. THE CHANCE OF FROZEN WILL BE HIGHLY DEPENDENT ON HOW MUCH
DIURNAL FALL CAN OCCUR IN BREAKS IN THE OVERCAST AS MID-LEVEL
CLOUD COVER HAS ALREADY OVERTAKEN WESTERN CWA THIS AFTERNOON. LOWS
WILL GENERALLY BE HELD UP BY THIS CLOUD COVER AND WILL RANGE FROM
30S TO NEAR 40 IN MOST LOCATIONS...STILL WELL ABOVE NORMAL.
WHATEVER PRECIP DOES MANAGE TO SNEAK INTO THE FAR NORTHERN ZONES
WILL BE SHORT-LIVED AS POPS DECREASE THROUGH THE DAY WITH THE
BOUNDARY REMAINING STATIONARY AND THEN STARTING A NORTHWARD
RETREAT. ANOTHER MILD DAY TOMORROW IS IN THE CARDS WITH SOUTHERLY
FLOW INCREASING AHEAD OF THE SURFACE LOW BACK OVER THE LOWER
MISSISSIPPI VALLEY. GUIDANCE SHOWING LOW 50S IN THE FAR NORTH AND
MOUNTAINS TO LOW 60S IN THE PIEDMONT...AGAIN AT LEAST 10F ABOVE
MID-DECEMBER CLIMO.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
AS OF 330 PM EST MONDAY...
ECMWF AND SREF A LITTLE SLOWER WITH QPF TUESDAY NIGHT...SO AGAIN
BACKED OFF ABOUT 6 HRS FROM PREVIOUS GRIDS. BEST CHC FOR RAIN WILL
BE WED MORNING...WITH JUST SPOTTY SHOWERS IN THE AFTERNOON. MAX T
WILL BE TOUGH THIS DAY BECAUSE RAIN ARRIVING EARLY IN THE MORNING
MAY MAKE IT DIFFICULT FOR TEMPS TO REBOUND IN THE AFTERNOON
DESPITE DOUBLE DIGIT H85 TEMPS. WENT A FEW DEGREES BELOW GUIDANCE...WITH
THE EXCEPTION OF THE SOUTHSIDE. SOME SLIGHTLY COOLER AIR DOES
ARRIVE ACROSS SE WEST VA LATE PM AND OVERNIGHT AS THE COLD FRONT
ENTERS THE CWA. ANOTHER WAVE WILL RIDE ALONG THE OLD DECAYING
BOUNDARY SUCH THAT RAIN ARRIVES MAINLY THURSDAY NIGHT. THE
GFS/ECMWF ARE IN GOOD AGREEMENT THIS FAR OUT SO INCREASED POPS.
PERHAPS SOME DOWNSLOPING AND CLEARING WILL ALLOW BETTER MIXING AND
THUS WARMER TEMPS ON THURSDAY IN COMPARISON TO WEDNESDAY. A WARM
BUT WET NIGHT FOLLOWS THURSDAY NIGHT. CONSIDERING CLOUDS AND H85
TEMPS WENT ABV GUIDANCE FOR MINS.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 330 PM EST MONDAY...
ECMWF/GFS DIVERGE MORE THOUGH INTO THE HOLIDAY WEEKEND...WITH THE
ECMWF PUSHING THE FRONT FURTHER OFF THE COAST IN COMPARISON TO THE
GFS. THE OP GFS IS QUICKER WITH A DISTURBANCE MOVING OUT OF THE
MIDWEST THAN THE ECMWF WHICH HOLDS MUCH OF THIS UPPER LEVEL
POSITIVELY TILTED TROUGH BACK INTO THE ROCKIES. THIS MEANS THAT
THE OP GFS HAS A STRONG ARCTIC HIGH OVER MAINE...AND DEVELOPS A
STRONG WEDGE WITH LOW PRESSURE GOING UP THE COAST EARLY SATURDAY.
THIS SOLUTION WOULD SUGGEST THE POTENTIAL FOR A WINTRY MIX ACROSS
THE SOUTHERN SHENANDOAH INITIALLY EARLY CHRISTMAS EVE DAY. THE
EUROPEAN...WHICH CONTINUES TO BE THE MORE SKILLFUL MODEL DAY 5 AT
H5...FROM 12Z...HOLDS THE HIGH PRESSURE FURTHER WEST INTO SE
CANADA...AND IT DOES NOT MOVE QUICK ENOUGH EAST TO WEDGE DOWN THE
APPALACHIANS...MEANING A WARMER SOLUTION WITH LOW PRESSURE
TRAVELING FURTHER WEST FROM THE COAST. CONFIDENCE IS LOW
ATTM...BUT WOULD LEAN MORE TOWARDS THE ECMWF EVEN THOUGH IT DOES
HAVE A STRONG BIAS WITH REGARDS TO SOUTHEASTERN US RIDGING. ON THE
CONTRARY...THE SE CONUS RIDGE HAS BEEN A DOMINANT FEATURE THIS
EARLY COOL SEASON SO A WARMER SOLUTION...LIKE THE ECMWF IS MORE
APPROPRIATE. THUS WILL HOLD BACK THE COLDEST AIR IN THE GRIDS
UNTIL MONDAY AND MONDAY NIGHT...WITH JUST RAIN THIS WEEKEND AND
SOME UPSLOPE SNOW SHOWERS ACROSS SE WEST VA CHRISTMAS DAY AND
EARLY MONDAY.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1150 PM EST MONDAY...
VFR MID TO HIGH CLOUDS THROUGH THE DAY TUESDAY...ONLY A VERY
SLIGHT CHANC FOR A STRAY SHOWER AT LWB DURING THE REMAINDER OF
EARLY TUESDAY MORNING OVERNIGHT HOURS BUT EXPECTING LOW END VFR TO
PREVAIL. JUST MENTIONED SHOWER IN VCNTY. OTHERWISE LOWERING CEILINGS
BY TUESDAY EVENING INTO OVERNIGHT WITH MVFR CIGS BETWEEN 00 AND 06
Z AT BLF...BCB...AND POSSIBLY DAN. GUIDANCE WANTS TO BRING IN VERY LOW
CIGS AND PERHAPS DRIZZLE TO BCB BEFORE 03Z WITH INCREASING SOUTHERLY
MOIST FLOW...BUT BLV A LITTLE OVERDONE WITH THIS. MORE LIKELY
BETWEEN 06 AND 09Z. ANY IFR CIGS AND VSBYS WITH LIGHT SHWRS OR
DRIZZLE WOULD BE CONFINED TO NEAR BLUE RIDGE TUES EVENING.
CLOSER TO DAWN WED MORNING BETTER CHANCE FOR SHWRS WITH MVFR TO
IFR CONDITIONS AT BLF...LWB...AND BCB...AND LIKELY ONLY ONLY BRIEF
PERIODS OF SUB VFR ELSWHERE LATER IN THE DAY WED. BRIEF VFR
RETURNS THURSDAY FOLLOWED BY A SECOND STORM SYSTEM BY FRIDAY WHICH
MAY BRING ANOTHER ROUND OF RAIN AS WELL AS LOW CIGS AND VSBYS
THURSDAY NIGHT INTO FRIDAY.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/KM
NEAR TERM...PC/SK
SHORT TERM...KM
LONG TERM...KM
AVIATION...JH/PC/SK/WP
AREA FORECAST DISCUSSION...UPDATED
NWS SPOKANE WA
245 PM PST Tue Dec 20 2011
.SYNOPSIS...A cold front will sweep through the Inland Northwest from
the north late this afternoon and this evening. This system is not
expected to carry much snow, but it will bring decidedly cooler
temperatures to the region as well as improving ventilation
conditions. An active winter weather pattern is expected to
continue through the holiday weekend and into the first part of
next week.
&&
.DISCUSSION...
Tonight...Satellite imagery indicates an upper level trough over
British Columbia dropping southeast towards Eastern Washington and
North Idaho. Instability in the mid levels of the atmosphere will
increase significantly this evening as 500mb temps fall to near
-36C and 850-500mb lapse rates increase to 7-8 C/KM. However
moisture is limited with this trough, and with 850mb winds of
15-25 knots out of the west to northwest significant down slope
flow off the higher terrain of Northern Washington and British
Columbia is likely. This should keep the best chances for snow
showers over the Cascades, Central Panhandle Mountains, Blue
Mountains, and Camas Prairie. Low level up slope flow into the
Palouse may also result in a brief light accumulation. An area of
lift from a passing vort max will also increase chances for snow
showers in these areas. The Camas Prairie looks to be the most
favored in this flow pattern but even here models only generate
one to two tenths of liquid precipitation so snow accumulations
were kept near 2 inches with no highlights needed at this time.
The cool and dry advection tonight with this trough will weaken
the inversion and will bring erosion of the stratus layer
especially over the northern valleys...and down the Okanogan
Valley into the western Columbia Basin. Patchy fog may form once
stratus clears but with the boundary layer drying out confidence
is not high so for now left mention of the forecast. JW
Wednesday through Friday...Through this portion of the forecast an
upper level low will pass out of the forecast area Wednesday morning,
then the weather will be dominated by a flat ridge of high
pressure through Thursday after. This will be followed by a
weakening/splitting weather disturbance Thursday night and Friday.
Challenges through this portion of the forecast will be the
probably of fog/stratus development with high pressure over the
region. Also, while model guidance all show a weakening frontal
system Thursday night the GFS/SREF show some weakening and a
slower solution than the NAM/EC/GEM. So far this season slower and
splitting weather systems have been the way and will lean in that
direction, what ever solution verifies confidence is not high
that there will be much snow.
Wednesday through Thursday northwest-north flow will keep some
snow showers over the southeast zones through about mid day
Wednesday, otherwise a dry and cool flow will result in a dry
forecast. The northerly flow and resultant cold air advection
should me enough to mix out the surface inversion and the
fog/stratus that has been going with it. There will most likely be
some regeneration of the fog along warmer water sources Thursday
morning, but expect this to be shallow and patchy. Temperatures
will cool by several degrees and be just on the cool side of normal.
Thursday night and Friday upper level moisture ahead of the
upstream weather system will move over the ridge. This should help
inhibit radiational cooling and keep the inversion from
strengthening any further. Model guidance is showing differing
solutions, but this trough passage is far from impressive. Some
isentropic ascent and upper level moisture is expected to track
through southern BC and will bring some light snow to the Cascade
crest and the northern mountains. Up-sloping will increase the
lift over the panhandle mountains, but with little moisture to
work with any snow accumulations will be very light. The following
cold front is almost non-existent at the surface but may be marginally
successful in keeping the boundary layer mixed. /Tobin
FRI NT THROUGH TUES: SIGNIFICANT CHALLENGES STILL EXIST AS A RESULT
OF MAJOR GUIDANCE TIMING DISAGREEMENTS BEGINNING CHRISTMAS EVE
AND LASTING THROUGH TUES. CONSENSUS IS TO STAY WITH THE LESS
PROGRESSIVE AND SOMEWHAT DRIER ECMWF, WHICH DELAYS THE COLD FRONT
PASSAGE THE GFS HAS FOR CHRISTMAS DAY UNTIL CHRISTMAS NIGHT. EVEN
SO, THE ECMWF STILL BEGINS TO PRODUCE LIGHT STRATIFORM SNOWS ALONG
A DEVELOPING...OR IN-SITU...WARM FRONTAL BOUNDARY BISECTING ERN WA
AND N ID MORE OR LESS WEST TO EAST WELL IN ADVANCE OF ITS OFFSHORE
COLD FRONT THAT THE GFS ALREADY HAS PAST SPOKANE BY MIDDAY
CHRISTMAS. WITH CHRISTMAS FIVE DAYS OUT, IT`S ESSENTIAL THAT WE
TREND IN THE DIRECTION OF THE MOST CONSISTANT GUIDANCE AND TRY TO
GIVE THE MAJOR POPULATION CENTERS MORE ATTENTION. THAT SAID, AND
BASED ON THE ABOVE MENTIONED GUIDANCE TRENDS, IT STILL LOOKS LIKE
SPOKANE WILL SEE SOME SNOW ON CHRISTMAS. THIS WILL BE ESPECIALLY
TRUE IF THE AFOREMENTIONED STATIONARY EAST-WEST FRONTAL BOUNDARY
SETS UP FARTHER SOUTH THAN EXPECTED. IT IS THIS BOUNDARY THAT WILL
BE THE PRIMARY SOURCE OF ISENTROPIC LIFT THAT WILL PRODUCE THE
INITIAL SNOW ON CHRISTMAS. DUE TO THE QUICK APPROACH OF THE UPPER
LOW, SNOW AMNTS SHOULDER NOT BE HEAVY. HOWEVER, THE HIGHEST AMNTS
WILL FALL ACROSS NRN WA AND N ID CHRISTMAS. A NOTE OF SIGNIFICANCE:
ONCE THE UPPER LOW CROSSES THE CASCADES CHRISTMAS NIGHT AND
CROSSES N ID MON (ASSUMING THIS TIMING IS CORRECT), N ID (AND
ESPECIALLY THE MTNS) WILL ENTER A VERY FAVORABLE PATTERN FOR
CONVECTIVE SNOWS AS THE POST FRONTAL LAPSE RATES STEEPEN AND THE
FLOW VEERS TO WESTERLY AND TAKES ON A MUCH MORE FAVORABLE UPSLOPE
COMPONENT. GUSTY WINDS STILL LOOK POSSIBLE INTO MONDAY.BZ
&&
.AVIATION...
18Z TAFs: Low stratus will continue to impact the majority of the
TAF sites this afternoon. The exception will be KPUW and KLWS where
a drier boundary layer from south-southeast winds should result in
VFR conditions persisting. A tough forecast in general for the
KGEG-KSFF-KCOE corridor as models indicate stratus hanging up in
this area with clearing to the south and stratus remaining locked in
to the north. Will rely on current trends and HRRR guidance for
this area. As winds switch to the southwest ahead of a cold front
late this afternoon and evening this will favor stratus advecting east
from the basin into the KGEG-KSFF-KCOE corridor as well as KPUW and
eventually KLWS. But then as drier advection moves in after 06z
behind the cold front should see some erosion of the stratus
especially KMWH/KEAT and probably KGEG and KSFF based on drying in
the boundary layer indicated by the NAM. Stratus will probably hang
in longer at KCOE/KPUW/KLWS with west-northwest winds favoring
stratus hanging up in these areas. A brief period of -SN may also
occur in these areas with the cold front especially KPUW.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 22 28 16 26 19 30 / 20 0 0 0 0 20
Coeur d`Alene 21 29 15 29 15 33 / 20 0 0 0 0 30
Pullman 25 30 15 30 21 34 / 40 10 0 0 0 10
Lewiston 30 33 20 35 22 37 / 50 10 0 0 0 10
Colville 21 29 10 30 18 32 / 20 0 0 0 0 10
Sandpoint 22 29 11 29 16 31 / 30 10 0 0 0 30
Kellogg 24 29 18 30 21 32 / 70 10 10 0 0 30
Moses Lake 22 33 14 31 18 32 / 0 0 0 0 0 10
Wenatchee 24 33 17 33 24 33 / 0 0 0 0 0 10
Omak 19 29 9 29 18 31 / 10 0 0 0 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
238 PM PST Tue Dec 20 2011
.SYNOPSIS...A cold front will sweep through the Inland Northwest from
the north late this afternoon and this evening. This system is not
expected to carry much snow, but it will bring decidedly cooler
temperatures to the region as well as improving ventilation
conditions. An active winter weather pattern is expected to
continue through the holiday weekend and into the first part of
next week.
&&
.DISCUSSION...
Tonight...Satellite imagery indicates an upper level trough over
British Columbia dropping southeast towards Eastern Washington and
North Idaho. Instability in the mid levels of the atmosphere will
increase significantly this evening as 500mb temps fall to near
-36C and 850-500mb lapse rates increase to 7-8 C/KM. However
moisture is limited with this trough, and with 850mb winds of
15-25 knots out of the west to northwest significant down slope
flow off the higher terrain of Northern Washington and British
Columbia is likely. This should keep the best chances for snow
showers over the Cascades, Central Panhandle Mountains, Blue
Mountains, and Camas Prairie. Low level up slope flow into the
Palouse may also result in a brief light accumulation. An area of
lift from a passing vort max will also increase chances for snow
showers in these areas. The Camas Prairie looks to be the most
favored in this flow pattern but even here models only generate
one to two tenths of liquid precipitation so snow accumulations
were kept near 2 inches with no highlights needed at this time.
The cool and dry advection tonight with this trough will weaken
the inversion and will bring erosion of the stratus layer
especially over the northern valleys...and down the Okanogan
Valley into the western Columbia Basin. Patchy fog may form once
stratus clears but with the boundary layer drying out confidence
is not high so for now left mention of the forecast. JW
Wednesday through Friday...Through this portion of the forecast an
upper level low will pass out of the forecast area Wednesday morning,
then the weather will be dominated by a flat ridge of high
pressure through Thursday after. This will be followed by a
weakening/splitting weather disturbance Thursday night and Friday.
Challenges through this portion of the forecast will be the
probably of fog/stratus development with high pressure over the
region. Also, while model guidance all show a weakening frontal
system Thursday night the GFS/SREF show some weakening and a
slower solution than the NAM/EC/GEM. So far this season slower and
splitting weather systems have been the way and will lean in that
direction, what ever solution verifies confidence is not high
that there will be much snow.
Wednesday through Thursday northwest-north flow will keep some
snow showers over the southeast zones through about mid day
Wednesday, otherwise a dry and cool flow will result in a dry
forecast. The northerly flow and resultant cold air advection
should me enough to mix out the surface inversion and the
fog/stratus that has been going with it. There will most likely be
some regeneration of the fog along warmer water sources Thursday
morning, but expect this to be shallow and patchy. Temperatures
will cool by several degrees and be just on the cool side of normal.
Thursday night and Friday upper level moisture ahead of the
upstream weather system will move over the ridge. This should help
inhibit radiational cooling and keep the inversion from
strengthening any further. Model guidance is showing differing
solutions, but this trough passage is far from impressive. Some
isentropic ascent and upper level moisture is expected to track
through southern BC and will bring some light snow to the Cascade
crest and the northern mountains. Up-sloping will increase the
lift over the panhandle mountains, but with little moisture to
work with any snow accumulations will be very light. The following
cold front is almost non-existent at the surface but may be marginally
successful in keeping the boundary layer mixed. /Tobin
FRI NT THROUGH TUES: SIGNIFICANT CHALLENGES STILL EXIST AS A RESULT
OF MAJOR GUIDANCE TIMING DISAGREEMENTS BEGINNING CHRISTMAS EVE
AND LASTING THROUGH TUES. CONSENSUS IS TO STAY WITH THE LESS
PROGRESSIVE AND SOMEWHAT DRIER ECMWF, WHICH DELAYS THE COLD FRONT
PASSAGE THE GFS HAS FOR CHRISTMAS DAY UNTIL CHRISTMAS NIGHT. EVEN
SO, THE ECMWF STILL BEGINS TO PRODUCE LIGHT STRATIFORM SNOWS ALONG
A DEVELOPING...OR IN-SITU...WARM FRONTAL BOUNDARY BISECTING ERN WA
AND N ID MORE OR LESS WEST TO EAST WELL IN ADVANCE OF ITS OFFSHORE
COLD FRONT THAT THE GFS ALREADY HAS PAST SPOKANE BY MIDDAY
CHRISTMAS. WITH CHRISTMAS FIVE DAYS OUT, IT`S ESSENTIAL THAT WE
TREND IN THE DIRECTION OF THE MOST CONSISTANT GUIDANCE AND TRY TO
GIVE THE MAJOR POPULATION CENTERS MORE ATTENTION. THAT SAID, AND
BASED ON THE ABOVE MENTIONED GUIDANCE TRENDS, IT STILL LOOKS LIKE
SPOKANE WILL SEE SOME SNOW ON CHRISTMAS. THIS WILL BE ESPECIALLY
TRUE IF THE AFOREMENTIONED STATIONARY EAST-WEST FRONTAL BOUNDARY
SETS UP FARTHER SOUTH THAN EXPECTED. IT IS THIS BOUNDARY THAT WILL
BE THE PRIMARY SOURCE OF ISENTROPIC LIFT THAT WILL PRODUCE THE
INITIAL SNOW ON CHRISTMAS. DUE TO THE QUICK APPROACH OF THE UPPER
LOW, SNOW AMNTS SHOULDER NOT BE HEAVY. HOWEVER, THE HIGHEST AMNTS
WILL FALL ACROSS NRN WA AND N ID CHRISTMAS. A NOTE OF SIGNIFICANCE:
ONCE THE UPPER LOW CROSSES THE CASCADES CHRISTMAS NIGHT AND
CROSSES N ID MON (ASSUMING THIS TIMING IS CORRECT), N ID (AND
ESPECIALLY THE MTNS) WILL ENTER A VERY FAVORABLE PATTERN FOR
CONVECTIVE SNOWS AS THE POST FRONTAL LAPSE RATES STEEPEN AND THE
FLOW VEERS TO WESTERLY AND TAKES ON A MUCH MORE FAVORABLE UPSLOPE
COMPONENT. GUSTY WINDS STILL LOOK POSSIBLE INTO MONDAY.BZ
&&
.AVIATION...
18Z TAFs: Low stratus will continue to impact the majority of the
TAF sites this afternoon. The exception will be KPUW and KLWS where
a drier boundary layer from south-southeast winds should result in
VFR conditions persisting. A tough forecast in general for the
KGEG-KSFF-KCOE corridor as models indicate stratus hanging up in
this area with clearing to the south and stratus remaining locked in
to the north. Will rely on current trends and HRRR guidance for
this area. As winds switch to the southwest ahead of a cold front
late this afternoon and evening this will favor stratus advecting east
from the basin into the KGEG-KSFF-KCOE corridor as well as KPUW and
eventually KLWS. But then as drier advection moves in after 06z
behind the cold front should see some erosion of the stratus
especially KMWH/KEAT and probably KGEG and KSFF based on drying in
the boundary layer indicated by the NAM. Stratus will probably hang
in longer at KCOE/KPUW/KLWS with west-northwest winds favoring
stratus hanging up in these areas. A brief period of -SN may also
occur in these areas with the cold front especially KPUW.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 22 28 16 26 19 30 / 20 0 0 0 0 20
Coeur d`Alene 21 29 15 29 15 33 / 20 0 0 0 0 30
Pullman 25 30 15 30 21 34 / 40 10 0 0 0 10
Lewiston 30 33 20 35 22 37 / 50 10 0 0 0 10
Colville 21 29 10 30 18 32 / 20 0 0 0 0 10
Sandpoint 22 29 11 29 16 31 / 30 10 0 0 0 30
Kellogg 24 29 18 30 21 32 / 70 10 10 0 0 30
Moses Lake 22 33 14 31 18 32 / 0 0 0 0 0 10
Wenatchee 24 33 17 33 24 33 / 0 0 0 0 0 10
Omak 19 29 9 29 18 31 / 10 0 0 0 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1226 PM PST Tue Dec 20 2011
.SYNOPSIS...The ridge of the past couple weeks will break down today
and tonight as a robust cold front sweeps in from the north.
Although this system won`t contain much snow, it will bring decidedly
cooler temperatures to the region as well as improving ventilation
conditions. A slightly more active winter weather pattern is
expected to continue through the end of the week and into the
holiday weekend.
&&
.DISCUSSION...
The forecast has been updated to end the air stagnation advisory.
Mixing potential will increase over the next 24 hours at cold
advection increases behind a cold front passage tonight.
For the rest of today minor adjustments have been made to lower
precipitation chances in some areas. Thus far precipitation has
been confined to the North Idaho Panhandle and Cascade crest area.
With westerly flow increasing this afternoon off the Cascades,
went with the NAM idea of areas in the lee of the Cascades such as
Leavenworth and Winthrop remaining in a snow shadow.
Meanwhile, precipitation chances will remain low today over the
Camas Prairie until the cold front passes through tonight. Thus
pops were lowered in this area for the afternoon hours. Pops were
also lowered this afternoon for Spokane with radar showing very
little in the way of precipitation in the area. Satellite indicated
a band of mid and high clouds moving over the stratus layer and
with the warm front already out of the area the westerly flow
should keep light snow activity this afternoon over the mountains
north and east of Spokane. JW
&&
.AVIATION...
18Z TAFs: Low stratus will continue to impact the majority of the
TAF sites this afternoon. The exception will be KPUW and KLWS where
a drier boundary layer from south-southeast winds should result in
VFR conditions persisting. A tough forecast in general for the
KGEG-KSFF-KCOE corridor as models indicate stratus hanging up in
this area with clearing to the south and stratus remaining locked in
to the north. Will rely on current trends and HRRR guidance for
this area. As winds switch to the southwest ahead of a cold front
late this afternoon and evening this will favor stratus advecting east
from the basin into the KGEG-KSFF-KCOE corridor as well as KPUW and
eventually KLWS. But then as drier advection moves in after 06z
behind the cold front should see some erosion of the stratus
especially KMWH/KEAT and probably KGEG and KSFF based on drying in
the boundary layer indicated by the NAM. Stratus will probably hang
in longer at KCOE/KPUW/KLWS with west-northwest winds favoring
stratus hanging up in these areas. A brief period of -SN may also
occur in these areas with the cold front especially KPUW.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 30 22 28 16 26 19 / 10 20 0 0 0 0
Coeur d`Alene 32 21 29 15 29 15 / 20 20 0 0 0 0
Pullman 37 25 30 15 30 21 / 20 40 10 0 0 0
Lewiston 38 30 33 20 35 22 / 10 50 10 0 0 0
Colville 32 21 29 10 30 18 / 20 20 0 0 0 0
Sandpoint 32 22 29 11 29 16 / 30 30 10 0 0 0
Kellogg 34 24 29 18 30 21 / 50 70 10 10 0 0
Moses Lake 32 22 33 14 31 18 / 0 0 0 0 0 0
Wenatchee 32 24 33 17 33 24 / 0 0 0 0 0 0
Omak 31 19 29 9 29 18 / 0 0 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
951 AM PST Tue Dec 20 2011
.SYNOPSIS...The ridge of the past couple weeks will break down today
and tonight as a robust cold front sweeps in from the north.
Although this system won`t contain much snow, it will bring decidedly
cooler temperatures to the region as well as improving ventilation
conditions. A slightly more active winter weather pattern is
expected to continue through the end of the week and into the
holiday weekend.
&&
.DISCUSSION...
Today through Wednesday morning...After a two week stay or so...the
persistent upper level ridge will be broken down by a well-
defined upper level trough currently moving toward the central BC
coast. The short-range models are in good agreement that a broad
swath of moisture ahead of this trough will dip south through the
forecast area during the day...hitting locations near the Canadian
border this morning and moving into the central portion of the
forecast area by afternoon. Precipitable water values within this
plume were around a half inch east of the Cascades which is around
150% of the seasonal normals and is surprisingly high considering
the cool in situ near ground temperatures and the track of the
system from the northwest. Nonetheless precipitation chances will
not be great as there is very little sign of an associated
surface-850 mb low and little variance from the west-northwest
flow at 850 mbs. Thus rain shadowing will be a big factor in
determining where precipitation falls. Given the flow pattern the
best chances for measurable precipitation today will occur near
the Cascades and over the Idaho Panhandle. As is typically the
case with systems diving down from the northwest...QPF amounts are
generally very light and this will likely prove no exception. We
have penciled in amounts of an inch or less for locations near the
Cascade crest...including the upper Methow Valley...and less than
half an inch for locations over the north Idaho Panhandle. By
evening the upper level trough tracks across the International
Border bringing a cold front with it. 500 mb temperatures plummet
to -36c or cooler resulting in a rapid destabilization. This will
likely manifest itself as a few snow showers...but they won`t be
widespread as the dendritic layer becomes sapped of appreciable
moisture...at least across the northern portions of the forecast
area. The southeast half of the forecast area...Palouse...Lewiston
area...Blue Mountains and Camas Prairie stand to see the most
appreciable weather from the approaching trough. The flow behind
the cold front will turn to more of a north-northwest orientation
which will combine with the destabilization during the overnight
portions of the forecast. The combination of upper level ascent
associated with the shortwave trough and the orographic ascent
through an unstable layer will result in widespread shower
activity...but even so QPF and snow amounts will be somewhat
underwhelming as the system moves through very quick. The models
continue to trend QPF amounts downward with most of the activity
ending by Wednesday morning. At this point we have placed around
1-2 inches of snow with local 3 inch amounts over the central
Panhandle, Blue Mountains, and Camas Prairie. Although this is
significant compared to what has occurred lately, it is well below
winter headline criteria. For the Lewiston and Pullman areas less
than an inch will accumulate overnight.
While this storm will likely underwhelm from a snow perspective it
will finally rid us of the persistent inversions which have
plagued much of the Columbia Basin for the past couple weeks. The
air stagnation advisory will finally be allowed to end with the
arrival of the cooler and drier air from the north. fx
Wednesday afternoon through Friday: By Wednesday afternoon, a mid-
level system will have pushed southeast of the area. Model
agreement on a faster solution seems to be fairly strong at this
time, with the GFS the slowest guidance by 18z Wednesday. Even as
the slowest guidance, the GFS still have the mid-level wave axis
extending from roughly Boise to Billings, which places it far to
the southeast of our forecast area. With the faster speed,
subsequent drying and cold air advection behind it will already be
into high gear. Strong model consensus on drying the entire CWA
from 700 mb upward exists by 18z Wednesday, with only weak
moisture from the surface to 700 mb remaining over the central
Idaho Panhandle. Because of this, PoPs were slashed everywhere,
and the only remnant of a chance of snow showers will be the
highest terrain of Shoshone County while exceedingly weak upslope
850 mb flow turns basically calm by the end of the afternoon.
As Tuesday night/early Wednesday`s system continues to depart to
the southeast, short wave ridging and surface high pres sue builds
into the area. With a complete boundary layer air mass changeover
likely, it seems probable that even with subsidence incoming, fog
may be tough to form given the dry Canadian origins of the
environment by that juncture. Fog has been excluded from the
forecast as a result, however it may still be possible along local
rivers and lakes that will act as a surface layer moisture source.
Additionally, meager layer moisture above the boundary layer means
a very clear night by be in store. With surface high pressure
overhead, a dry air mass, and clear skies, temperatures are likely
to fall to their lowest levels of the season in many spots. The
forecast remains largely below guidance, however the new GFS grids
suggest that many of the northern valleys will fall below 0F.
While it seems likely some locations will do this, the lack of
widespread snow cover in the valleys will make this an isolated
rather than widespread scenario.
The 00z guidance tonight has also come into a stronger cluster
with the arrival of the next system to affect the area. All signs
from the NAM/GEM/GFS/ECMWF point to isentropic and slop over
precipitation reaching the crest and near crest of the Cascades
overnight Thursday night. Given the cold air in place, all
precipitation is likely to be snow, however, the mid-level system
never closes off and moisture again looks limited. As a result,
low level westerlies will likely create an expansive precipitation
shadow east of the Cascades that may well extend all the way to
the Idaho Panhandle mountains. PoPs east of the Cascades and
throughout most of eastern Washington are very limited as a
result.
Beyond Friday: Model and ensemble guidance continues to point at a
transient ridge shifting through the area next weekend with its
departure targeted for Sunday night. After that time, early
indications are that a wetter on shore flow pattern may result,
however model solutions become much more scatter shot with any
system location let alone show any agreement over the direction of
the flow over the area. As a result, after a mostly dry weekend,
PoPs trend quickly toward climatology into next week. /Fries
&&
.AVIATION...
18Z TAFs: Low stratus will continue to impact the majority of the
TAF sites this afternoon. The exception will be KPUW and KLWS where
a drier boundary layer from south-southeast winds should result in
VFR conditions persisting. A tough forecast in general for the
KGEG-KSFF-KCOE corridor as models indicate stratus hanging up in
this area with clearing to the south and stratus remaining locked in
to the north. Will rely on current trends and HRRR guidance for
this area. As winds switch to the southwest ahead of a cold front
late this afternoon and evening this will favor stratus advecting east
from the basin into the KGEG-KSFF-KCOE corridor as well as KPUW and
eventually KLWS. But then as drier advection moves in after 06z
behind the cold front should see some erosion of the stratus
especially KMWH/KEAT and probably KGEG and KSFF based on drying in
the boundary layer indicated by the NAM. Stratus will probably hang
in longer at KCOE/KPUW/KLWS with west-northwest winds favoring
stratus hanging up in these areas. A brief period of -SN may also
occur in these areas with the cold front especially KPUW.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 30 22 28 14 26 20 / 20 20 0 0 0 0
Coeur d`Alene 30 21 29 15 29 15 / 20 20 0 0 0 0
Pullman 37 25 30 15 30 22 / 30 40 10 0 0 0
Lewiston 38 30 33 20 35 22 / 10 50 10 0 0 0
Colville 32 23 29 10 30 19 / 20 20 0 0 0 0
Sandpoint 32 22 29 11 29 16 / 30 30 10 0 0 0
Kellogg 33 24 29 18 30 22 / 50 70 10 10 0 0
Moses Lake 32 22 33 14 31 18 / 0 0 0 0 0 0
Wenatchee 32 24 34 17 33 24 / 0 0 0 0 0 0
Omak 31 19 29 9 29 19 / 10 0 0 0 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Air Stagnation Advisory until Noon PST today for Central
Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse-
Lewiston Area-Northern Panhandle.
WA...Air Stagnation Advisory until Noon PST today for East Slopes
Northern Cascades-Lower Garfield and Asotin Counties-Moses
Lake Area-Northeast Mountains-Okanogan Highlands-Okanogan
Valley-Spokane Area-Upper Columbia Basin-Washington Palouse-
Waterville Plateau-Wenatchee Area.
&&
$$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
832 PM CST WED DEC 21 2011
.UPDATED...LOWERED THE PROBABILITY OF SNOW IN THE FORECAST OVER
MOST OF THE AREA NORTH OF A WAUSAU TO GREEN BAY LINE. INITIAL SNOW
OVER NORTHCENTRAL WISCONSIN DURING THE LATE AFTERNOON AND EARLY
EVENING HAD THE BENEFIT OF LOW LEVEL WARM ADVECTION AND
CONVERGENCE IN ADDITION TO THE UPPER JET DYNAMICS. THE LOW LEVEL
FORCING HAS SINCE DIMINISHED AND SO HAS THE SNOW.
AS OF 830 PM THERE WERE ECHOES OVER THE CENTRAL PART OF THE
FORECAST AREA BUT LITTLE OR NOTHING REACHING THE GROUND DUE TO
VERY DRY AIR INITIALLY ACROSS THE AREA. THE PRECIPITABLE WATER OF
THE 00Z GREEN BAY SOUNDING WAS ONLY .22 INCHES. THE MINNEAPOLIS
SOUNDING STARTED OFF SIMILARLY AT 12Z AND MOISTENED UP TO ABOUT
.40 INCHES BUT ONLY MANAGED A TRACE OF SNOW. ALL IS NOT LOST FOR
THOSE WISHING FOR SNOW AS SOME BETTER RADAR REFLECTIVITIES OVER
IOWA ARE MOVING TO THE NORTHEAST. THESE CORRELATE WELL WITH THE
500MB DIVERGENCE OF THE 00Z RUC WHICH WOULD TAKE THIS SNOW
GENERALLY TO THE AREA SOUTH OF A KEWAUNEE TO WAUPACA.
THINK THAT THE ATMOSPHERE WILL MANAGE TO PRODUCE SOME LIGHT SNOW
OR AT LEAST FLURRIES IN THE FOX VALLEY...LAKESHORE AND WAUSHARA
AND WAUPACA COUNTIES LATE TONIGHT OR EARLY THURSDAY BUT PROBABLY
JUST A DUSTING TO A HALF INCH DUE TO THE DRY AIR CURRENTLY IN
PLACE.
RDM
&&
.PREV DISCUSSION...ISSUED AT 624 PM CST WED DEC 21 2011...
SHORT TERM...TONIGHT AND THURSDAY...SNOW TRENDS AND ACCUMULATIONS
ARE THE MAIN FCST CONCERNS.
A COLD FRONT WAS MOVG THROUGH THE NW HALF OF THE CWA THIS AFTERNOON.
MID-LEVEL FRONTOGENETIC FORCING SITUATED JUST NW OF THE FRONT WAS
GENERATING A BAND OF LIGHT SNOW FROM CENTRAL MN INTO NC WI...WITH
OCNL VSBYS OF 1-2SM. MODELS ARE IN GENERAL AGREEMENT THAT THIS
BAND OF SNOW WILL GRADUALLY WEAKEN DURING THE LATE AFT/EARLY EVG...
WITH ANOTHER MORE SIGNIFICANT BAND SETTING UP OVER PARTS OF C/EC WI
LATE TONIGHT. HAVE KEPT CHC POPS ACROSS THE NW TWO-THIRDS OF THE CWA
THIS EVG...THEN LIKELY POPS MAINLY SOUTH OF A MFI-SUE LINE AFTER
MIDNIGHT. THE SNOW WILL CONTINUE TO SAG SOUTH THROUGH OUR SOUTHERN
COUNTIES ON THURSDAY MORNING...AND SHOULD BE OUT OF THE FA BY
MIDDAY. DON`T THINK THAT SNOWFALL TOTALS WILL GET OUT OF HAND...
AS THE INITIAL AIR MASS IS QUITE DRY...AND THERE IS LITTLE
EVIDENCE OF ANY INSTABILITY THAT MIGHT ENHANCE/FOCUS THE FGEN
FORCING. REGARDLESS...IT APPEARS THAT PARTS OF C/EC WI WILL SEE
AROUND AN INCH OF SNOW...WHICH COULD MAKE FOR A SLIPPERY COMMUTE
ON THURSDAY MORNING.
COLDER NNW FLOW WILL BRING A CHC OF LAKE-EFFECT SNOW SHOWERS TO
NC WI LATE TONIGHT INTO THURSDAY. WITH LIGHT WINDS (10-15 KTS)
IN THE 925-850 MB LAYER...WOULD NOT EXPECT THE SNOW SHOWERS TO
MOVE VERY FAR INLAND...SO WILL MAINLY CONFINE POPS TO VILAS
COUNTY FOR NOW.
LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY.
STILL NO SIGNIFICANT CHANGES IN SPLIT FLOW PATTERN THRU FIRST
PART OF NEXT WEEK. SOME HINT OF MORE ZONAL/WNW FLOW PATTERN LATER
NEXT WEEK. OVERALL...WEATHER QUIET FOR THIS TIME OF YEAR.
SERIES OF NW PACIFIC SYSTEMS MOVE ACROSS THE REGION DURING THIS
PERIOD IN NORTHERN STREAM...BUT LITTLE IN THE WAY OF WEATHER
OUTSIDE OF CLOUDS AND FLURRIES...AS THESE SYSTEMS ARE MOISTURE-
STARVED DUE TO SPLIT FLOW. BOTH 21/12Z GFS AND ECMWF INDICATE
SYSTEM ON FRIDAY HAS ENOUGH UPPER LEVEL DYNAMICS TO OVERCOME
INITIALLY DRY COLUMN AND PRODUCE A PERIOD OF SNOW SHOWERS ACROSS
THE NORTH THIRD.
TEMPERATURES WILL BE ABOVE NORMAL FOR MUCH OF PERIOD AS ARCTIC
AIR REMAINS GENERALLY BOTTLED UP N OF 50 N.
&&
.AVIATION...GENERALLY VFR THIS EVENING EXCEPT FOR A BAND OF LIGHT
SNOW WITH MVFR CIGS AND VSBYS THAT WILL BE MOVING SLOWLY SOUTH
ACROSS THE AREA. LATER TONIGHT MVFR CIGS EXPECTED ACROSS THE
ENTIRE AREA.
RDM
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
325 PM CST TUE DEC 20 2011
.VERY SHORT TERM...TONIGHT AND WEDNESDAY.
BAND OF LIGHT RAIN/LIGHT SNOW SHOWERS CURRENTLY IN FAR NORTHERN
ILLINOIS SHOULD PUSH INTO THE FAR SOUTHERN COUNTIES THROUGH THE REST
OF THE AFTERNOON. ROCKFORD ASOS REPORTED A PERIOD OF RAIN AND SNOW
WITH THIS BAND...WITH RUC FORECAST SOUNDINGS IN THE AREA SHOWING WEB
BULB NEAR FREEZING. THIS AREA BEING DRIVEN BY LOW LEVEL WARM AIR
ADVECTION AND MID LEVEL FRONTOGENESIS RESPONSE. THIS AREA OF
PRECIPITATION BEING SLOWED IN ITS ADVANCE BY DRIER AIR PUSHING
SOUTHEAST INTO THE AREA.
LOCAL HIGH RESOLUTION MODELS NOT DOING A GOOD JOB WITH CAPTURING
THIS BAND. THINKING FOR THE REST OF THE AFTERNOON WOULD BE TO
MENTION LIGHT RAIN SHOWERS/SNOW SHOWERS IN THE FAR SOUTHERN
COUNTIES. WARM AIR ADVECTION SHIFTS EAST BY 00Z WEDNESDAY...SO THINK
THIS BAND WILL WEAKEN AND DISSIPATE BY THEN. WILL HAVE TO KEEP AN
EYE ON IT INTO THE EARLY EVENING...AS IT MAY AFFECT ROADS WITH A
DUSTING OF SNOW INTO THE EARLY EVENING IN THIS AREA.
ONCE THIS DISSIPATES BY EARLY EVENING...NEXT ISSUE WILL BE DRIZZLE
AND VERY LIGHT RAIN WITH PASSING UPPER LEVEL LOW TONIGHT AND EARLY
WEDNESDAY. WEAK LOW LEVEL FRONTOGENESIS RESPONSE CLIPS THE FAR
SOUTHERN AND SOUTHEASTERN COUNTIES THIS EVENING...EXITING THE
SOUTHEAST BY EARLY WEDNESDAY MORNING. UPPER LOW TRACKS NORTHEAST TO
FAR EASTERN IOWA BY 12Z WEDNESDAY...WITH DIFFERENTIAL CYCLONIC
VORTICITY ADVECTION INTO THE FORECAST AREA AHEAD OF IT.
AREA FORECAST SOUNDINGS SATURATE IN THE LOW LEVELS FROM SOUTHEAST TO
NORTHEAST ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA THIS
EVENING...REMAINING SO INTO WEDNESDAY MORNING. SOUNDINGS SUPPORT
VERY LIGHT RAIN/DRIZZLE ACROSS THE SOUTHEAST AND FAR SOUTHERN
COUNTIES TONIGHT. POTENTIAL FOR LIGHT FREEZING DRIZZLE REMAINS IN
AREAS MAINLY SOUTH AND SOUTHWEST OF MADISON...WHERE TEMPERATURES ARE
EXPECTED TO DIP BELOW FREEZING.
PRECIPITATION SHOULD CLEAR THE FAR SOUTHEAST BY LATE WEDNESDAY
MORNING. DRIER AIR WORKING INTO THE LOW LEVELS SHOULD THEN BRING
QUIET WEATHER THROUGH THE AFTERNOON...WITH CLOUDS GRADUALLY MIXING
OUT FROM WEST TO EAST.
.SHORT TERM...WEDNESDAY NIGHT THROUGH FRIDAY.
FOCUS OF THIS PERIOD ON INCREASING THREAT FOR LIGHT PRECIPITATION
WEDNESDAY NIGHT INTO THURSDAY. SHORT TERM GUIDANCE IN REASONABLE
AGREEMENT ON WEAK ISENTROPIC FORCING SPREADING ACROSS PORTIONS OF
SOUTH CENTRAL WI LATER WED NIGHT INTO THU. WEAK ISENTROPIC FORCING
ON 295 THETA SFC ENHANCED BY RIGHT ENTRANCE REGION OF 300H JET
MOVING TO THE EAST ACROSS THE NORTHERN GTLAKES. HENCE WL ADD LOW
CHANCE POPS ACROSS NRN CWA. BEST FORCING SLIDES TO THE EAST THU
MRNG. WL CONT SCHC WORDING AS WEAK ISENTROPIC OMEGA AND WEAK 700H
WAVE SLIDES ACROSS SRN WI.
LOW LEVEL FLOW TURNS TO THE NORTH THU NIGHT. LOW LEVEL WINDS REMAIN
MORE NORTHERLY ON NAM WHILE GFS MORE NORTHEAST. WITH DELTA-T AROUND
15C...GFS WOULD HINT AT POSSIBLY PERIOD OF -SHSN OVER LAKESHORE
COUNTIES THU EVE. INITIAL MOISTURE QUESTIONABLE...AND LOW LEVELS
GRADUALLY DRY OUT THU NIGHT...SO WEAK LAKE EFFECT THREAT DIMINISHES
AFT MIDNIGHT. FOR NOW...DUE TO UNCERTAINTY IN LOW LEVEL WINDS...WL
HAVE SCHC WORDING DURING THE EVE. COLDER AIR IN PLACE ON FRIDAY AS
HIGH PRESSURE RIDGING PASSES THROUGH SRN WI.
.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY.
UNCERTAINTIES APPEAR RIGHT AWAY IN THE EXTENDED PERIOD AS BOTH ECMWF
AND GFS HAVING DIFFICULTIES DETERMINING STRENGTH OF SPLIT FLOW
ACROSS CONUS AND WESTERLIES ACROSS UPPER MIDWEST. EXTENDED GUIDANCE
NOW TRENDING TOWARD STRONGER WEST TO NORTHWEST FLOW ACROSS NORTHERN
CONUS INCLUDING WRN GTLAKES FOR DURATION OF PERIOD...HENCE
INCREASING CONFIDENCE. GFS ENSEMBLE MEMBERS ALSO SHOWING BETTER
AGREEMENT FOR THIS PATTERN AS WELL. THIS SCENARIO RESULTS IN DEEP
MOISTURE REMAINING WELL SOUTH OF AREA...AVAILABLE TO TAP INTO FOR
MORE UNSETTLED FLOW ACROSS SRN CONUS.
WITH MOSTLY ZONAL TO WNW FLOW AND DEEP MOISTURE TO THE
SOUTH...EXTENDED PERIOD FOR SRN WI LOOKING FAIRLY QUIET WITH
TEMPERATURES AVERAGING OUT NEAR OR SLIGHTLY ABOVE NORMAL DUE TO LACK
OF SNOW COVER. BOTH ECMWF AND GFS INDICATE LONG WAVE TROUGH MOVING
THRU WRN GTLAKES LATE IN THE HOLIDAY WEEKEND. ECMWF INCLUDES A
STRONGER SHORT WAVE SLIDING SOUTHWARD AND DEEPENING IN LONG WAVE
TROUGH. MOISTURE WILL BE MINIMAL AND NEITHER GEM OR GFS SHOWING
THIS STRONGER FEATURE. MEDIUM RANGE ENSEMBLE POPS ALSO REMAIN LESS
THAN 10 PERCENT. HENCE WL CONTINUE DRY FORECAST FOR NOW THROUGH THE
HOLIDAY WEEKEND.
WL NEED TO KEEP ONE EYE ON DEVELOPING LOW PRESSURE OVER SOUTHEAST
CONUS XMAS EVE AS IT TRACKS NORTHEAST ON XMAS DAY...HOWEVER
PREDOMINANT WEST TO NORTHWEST FLOW OVER NORTHERN CONUS SHOULD KEEP
THIS SYSTEM WELL TO THE SOUTHEAST.
LONG WAVE TROUGH CONTINUES ITS TREK EWD LATE IN THE WEEKEND AND
EARLY MONDAY...WITH ZONAL FLOW RETURNING FOR THE FIRST PART OF THE
WEEK. GFS 5DAY 500H MEANS INDICATES THIS FLOW WL CONTINUE THROUGH
THE LAST DAYS OF THE YEAR WITH GRADUALLY LOWERING HEIGHTS. EXPECT
WEAK SHORT WAVES TRAVERSING WESTERLIES TO OCCASIONALLY THREATEN SRN
WI WITH LIGHT PRECIP DURING THIS PD.
&&
.AVIATION /00Z TAFS/...BAND OF LIGHT RAIN AND LIGHT SNOW SHOWERS
WILL AFFECT KENOSHA UNTIL AROUND 00Z WEDNESDAY. QUESTIONABLE IF IT
WILL MAKE IT TO MILWAUKEE...WAUKESHA AND MADISON WITH DRIER AIR TO
THE NORTH SLOWING ITS ADVANCE. FOR NOW...WILL MENTION VICINITY IN
TAFS BUT NOT PREVAILING. SOME MVFR CEILINGS AND VISIBILITIES
POSSIBLE IN THIS BAND...ALONG WITH A DUSTING OF SNOW ON RUNWAYS.
MVFR CEILINGS AND VISIBILITIES ARE EXPECTED TO SHIFT NORTHWARD TO
TAF SITES DURING THE EVENING. LIGHT DRIZZLE IS EXPECTED AT THE
EASTERN SITES BETWEEN 03Z TO 15Z WEDNESDAY...WITH LIGHT RAIN
POSSIBLE AT KENOSHA. PATCHY LIGHT FREEZING DRIZZLE IS POSSIBLE AT
MADISON BETWEEN 09Z AND 13Z WEDNESDAY...BUT WILL LEAVE OUT OF TAFS
FOR NOW DUE TO SOME UNCERTAINTY WITH HOW FAR NORTHWEST THE DRIZZLE
WILL REACH.
VFR CONDITIONS SHOULD RETURN BY 15Z TO 16Z WEDNESDAY ACROSS TAF
SITES...AND REMAIN THROUGH THE REST OF THE DAY. LIGHT SOUTH WINDS
TODAY WILL BECOME VARIABLE TONIGHT...THEN SOUTHWEST TO WEST BY
MIDDAY WEDNESDAY.
&&
.CONFIDENCE...
TONIGHT AND WEDNESDAY...MEDIUM.
WEDNESDAY NIGHT AND THURSDAY...LOW TO MEDIUM.
THURSDAY NIGHT AND FRIDAY...MEDIUM TO HIGH.
FRIDAY NIGHT THROUGH TUESDAY...MEDIUM.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
SHORT TERM/LONG TERM...MBK
VERY SHORT TERM/AVIATION/MARINE...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1120 PM CST MON DEC 19 2011
.SHORT TERM...THROUGH WEDNESDAY NIGHT
246 PM CST MON DEC 19 2011
MAIN FORECAST CONCERN IS WITH THE PRECIPITATION CHANCES AND TYPES
TUESDAY AND TUESDAY NIGHT.
SURFACE ANALYSIS THIS AFTERNOON SHOWS A NEARLY STATIONARY FRONT
FROM LOWER MICHIGAN TO AN AREA OF LOW PRESSURE OVER EASTERN NEW
MEXICO. HIGH PRESSURE WAS CENTERED OVER THE WESTERN DAKOTAS AND
EASTERN MONTANA.
STRATUS CLOUDS HAVE COME IN BEHIND THE COLD FRONT AND COVERED
ALMOST THE ENTIRE AREA THIS AFTERNOON. VISIBLE SATELLITE DOES
SHOW QUITE A FEW HOLES IN THE CLOUD FIELD AND THE CLOUDS ALSO
APPEAR TO BE THINNING OUT. THE 19.12Z NAM BUFKIT SOUNDINGS WOULD
SUGGEST THE CLOUDS SHOULD SCATTER OUT THIS EVENING WHILE SEVERAL
RUNS NOW OF THE RUC DO NOT SCATTER THE CLOUDS OUT UNTIL THE
OVERNIGHT HOURS. HAVE TRIED TO BALANCE THESE MODEL TRENDS WITH THE
CURRENT SATELLITE TRENDS TO SHOW CLEARING THROUGH THE EVENING FOR
MOST OF THE AREA. THIS WILL ALSO HAVE A BIG IMPACT ON THE
TEMPERATURES. HAVE BUMPED THE TEMPERATURES UP SOME...ESPECIALLY
ACROSS THE NORTH WHERE THE CLOUDS MAY HOLD ON THE LONGEST...BUT IF
THEY CLEAR OUT EARLIER THAN EXPECTED...THESE WILL HAVE TO BE MOVED
DOWN.
THE STORM SYSTEM OVER THE SOUTHWEST WILL BE EJECTING NORTHEAST
TOWARD THE OHIO RIVER VALLEY AND EASTERN GREAT LAKES FOR TUESDAY
THROUGH WEDNESDAY. AFTER A NORTHWARD JOG IN THE TRACK OF THIS
SYSTEM WITH YESTERDAY/S MODELS...ALL THE 19.12Z MODELS HAVE
SETTLED BACK SOUTH WITH THE TRACK. IT ONCE AGAIN APPEARS THAT THE
SOUTHERN PARTS OF THE AREA WILL EITHER GET BRUSHED WITH THIS SYSTEM
OR IT WILL JUST MISS TO THE SOUTH. THE NAM AND GFS STILL SHOW
DECENT FORCING WITH THIS SYSTEM JUST GOING BY TO THE SOUTH.
BETWEEN 4 AND 8 PVU/S OF VORTICITY ADVECTION IN THE 500-300 MB
LAYER PASSES BY TUESDAY AFTERNOON AND NIGHT. THE BEST QG
CONVERGENCE IS EXPECTED TO MISS THE AREA WITH JUST SOME WEAK
CONVERGENCE IN THE 700-500 MB LAYER COMING THROUGH TUESDAY NIGHT.
STILL EXPECTING TO SEE SOME WEAK FRONTOGENESIS IN THE 850-500 MB
LAYER AS WELL. ONE THING THAT HAS NOT CHANGED IN THE MODELS...IS
WHETHER THERE WILL BE ICE PRESENT IN THE CLOUDS. BUFKIT SOUNDINGS
ACROSS THE FAR SOUTH CONTINUE TO SUGGEST CLOUD TOP TEMPERATURES
ONLY AROUND -10C WHICH COULD LEAD TO MORE LIQUID INSTEAD OF SNOW.
HAVE CONTINUED WITH THE MIX OF FREEZING RAIN/RAIN AND SNOW BUT
WITH ONLY LIGHT PRECIPITATION AMOUNTS ANTICIPATED...ANY SNOW OR
ICE ACCUMULATIONS WILL BE VERY LIGHT.
ONCE THIS SYSTEM GOES BY...A NORTHERN STREAM SHORT WAVE TROUGH
WILL MOVE ALONG THE CANADIAN BORDER WEDNESDAY NIGHT. THIS WAVE
WILL PUSH A COLD FRONT INTO THE AREA THAT COULD POSSIBLY PRODUCE
SOME LIGHT SNOW AND HAVE CONTINUED WITH THE LOW END SNOW CHANCES
ACROSS THE NORTH WITH THIS SYSTEM.
.LONG TERM...THURSDAY THROUGH MONDAY
246 PM CST MON DEC 19 2011
THE COLD FRONT WILL CONTINUE TO PUSH SOUTH ACROSS THE REMAINDER OF
THE AREA THURSDAY AND COULD STILL BE PRODUCING SOME LIGHT SNOW.
ADDED IN SOME LOW END SNOW CHANCES TO HANDLE THIS POSSIBILITY.
ONCE THIS SYSTEM GOES BY...THE REMAINDER OF THE PERIOD LOOKS TO BE
PRETTY QUIET. ANOTHER NORTHERN STREAM WAVE COULD BRUSH THE UPPER
MIDWEST CHRISTMAS DAY AND HAVE CONTINUED WITH THE LOW SNOW CHANCES
ACROSS THE NORTHERN PART OF THE FORECAST AREA AS THE BEST FORCING
WITH THIS WAVE LOOKS TO REMAIN TO THE NORTH OF THE AREA.
&&
.AVIATION...THROUGH 06Z WEDNESDAY
1120 PM CST MON DEC 19 2011
THE MAIN CONCERN FOR THE TERMINAL IS IN THE VERY NEAR TERM WITH
HOW LONG THE 2500FT CEILINGS HOLD ON AT RST. AS OF 5Z...THERE IS A
NARROW STRIP OF THESE LOWER CEILINGS THAT EXTENDS FROM PRESTON
NORTH THROUGH ROCHESTER TOWARD THE TWIN CITIES. THE CLEARING BACK
EDGE IS A COUNTY AWAY TO THE WEST AND IS EXPECTED TO EVENTUALLY
WORK EASTWARD. FOR NOW...HAVE KEPT SOME 2500FT CIGS IN THERE FOR A
FEW HOURS BEFORE THEY CLEAR OUT. OTHERWISE AT LSE...CEILINGS HAVE
BEEN VFR THROUGH THE NIGHT AND ARE EXPECTED TO REMAIN THAT WAY
THROUGH THE MORNING. BEYOND THIS...WINDS WILL REMAIN LIGHT AND
COME AROUND TO THE SOUTH TODAY AS A RIDGE AXIS MOVES THROUGH. HIGH
CLOUDS WILL CONTINUE TO BLANKET THE REGION WELL TO THE NORTH OF A
POTENT STORM SYSTEM MOVING THROUGH THE PLAINS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
246 PM CST MON DEC 19 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...04
LONG TERM...04
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
250 AM EST THU DEC 22 2011
.SYNOPSIS...
A SLOW MOVING FRONTAL SYSTEM WILL REMAIN NEAR THE FORECAST AREA
THROUGH THE CHRISTMAS WEEKEND. A SERIES OF LOW PRESSURE SYSTEMS WILL
MOVE NORTHEASTWARD ALONG THE FRONT.
&&
.NEAR TERM /THROUGH TODAY/...
SCATTERED SHOWERS DEVELOPING ACROSS SOUTH GEORGIA THIS MORNING
ASSOCIATED WITH WARM ADVECTION. LATEST RUC SUGGESTS THESE SHOWERS
WILL CONTINUE TO TRACK NORTHEAST INTO THE CSRA LATER THIS MORNING
AND ACROSS THE MIDLANDS. BASED ON 850MB TEMPERATURES EXPECT ANOTHER
WARM DAY WITH TEMPERATURES IN THE LOWER 70S. MAY BE HIGHER IF
BREAKS IN THE CLOUDS THIS AFTERNOON.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
WEAK CONVERGENCE AND MOISTURE ASSOCIATED WITH THE SLOW MOVING
FRONT WILL SUPPORT A CONTINUED SHOWER CHANCE...ALTHOUGH WITH LACK
OF UPPER LEVEL SUPPORT...AND LOW SREF POPS...DECREASED POPS FROM
PREVIOUS FORECAST INTO FRIDAY MORNING. THE NAM AND GFS SHOW SOME
DRYING DEVELOPING FRIDAY AS THE FRONT PUSHES A LITTLE FARTHER
SOUTHEASTWARD.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
CONFIDENCE REMAINES LOW HOWEVER WITH THE FORECAST THROUGH THE
EXTENDED PERIOD. LATEST GFS/ECMWF ADVECTING MOISTURE FROM THE
GULF NORTHEAST INTO GEORGIA AND SOUTH CAROLINA FASTER THAN NAM
SATURDAY NIGHT AS NAM CLOSES OFF UPPER LOW IN THE SOUTHERN PLAINS.
POPS THOUGH SHOULD REMAIN LOW SATURDAY NIGHT. UNCERTAINTY
CHRISTMAS DAY WITH MEAN GFS ENSEMBLE POPS LOWER THAN OPERATIONAL
GFS. LITTLE CHANGE MADE TO FORECAST FOR CHRISTMAS...CHANCE POPS
AND TEMPERATURES ABOVE NORMAL SEEMS REASONABLE. DRYING MONDAY WITH
RIDGING BECOMING DOMINATE TUESDAY. TEMPERATURES NEAR NORMAL.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
MUCH OF THE RAINFALL FROM WEDNESDAY HAS MOVED NORTHEAST OF THE AREA.
ONLY A FEW SPRINKLES WILL MOVE ACROSS THE REGION FOR MUCH OF THE TAF
PERIOD...ESPECIALLY OVERNIGHT INTO THURSDAY MORNING.
MVFR CONDITIONS HAVE ALREADY DEVELOPED AT AGS/DNL AND EXPECT
MVFR/IFR CONDITIONS TO DEVELOP LATER TONIGHT AT THE REMAINDER TAF
SITES. EXPECT AREAS OF LOW CLOUDS AND FOG TO DEVELOP THROUGH THE
MORNING HOURS. BUFKIT CONTINUES WITH HIGH LOW-LEVEL MOISTURE AND
BRINGS IN SOME SLIGHTLY DRIER AIR ALOFT BY MORNING. MODELS ALL
SHOWING POSSIBLE LIFR/IFR CONDITIONS BY MORNING...WITH VISIBILITIES
LESS THAN A HALF A MILE. FOR NOW WILL NOT GO THAT LOW...BUT WILL
DROP VISIBILITIES IN THE MIDLANDS AND CSRA DOWN TO 1SM IN BR. WILL
NEED TO MONITOR OVERNIGHT THROUGH. CLOUDS STILL FORECAST TO DROP
DOWN BELOW 500 FT TOWARDS MORNING. CONDITIONS WILL SLOWLY IMPROVE
AFTER 16Z THURSDAY WITH IFR CIGS AND MVFR VSBYS. VFR CONDITIONS
POSSIBLE AFTER 22Z THURSDAY FOR A PERIOD IN THE AFTERNOON. SURFACE
WINDS WILL BE LIGHT FROM THE SOUTH-SOUTHWEST OVERNIGHT AND BECOME
MORE SOUTHERLY AND INCREASE TO NEAR 10 KNOTS ON THURSDAY.
EXTENDED AVIATION OUTLOOK...PERIODS OF CIG/VSBY RESTRICTIONS
EXPECTED THROUGH SATURDAY AS A SERIES OF WEATHER SYSTEMS CROSS THE
REGION.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
225 AM CST THU DEC 22 2011
.SYNOPSIS...
22.00Z 300 HPA JET ANALYSIS SHOWS THAT KANSAS LIES BETWEEN A STRONG
SOUTHERN JET EXTENDING FROM MEXICO TO THE LOWER MISSISSIPPI RIVER VALLEY
AND A NORTHERN JET WAS SLIDING EAST ACROSS THE NORTHERN PLAINS. A 75-85
KT JET WAS MOVING PUSHING SOUTHWARD UPSTREAM OF A 500 HPA LOW PRESSURE
CENTER LOCATED ACROSS EASTERN UTAH. MID ATMOSPHERE ANALYSIS INDICATES
COLD AIR OF -30 TO -37 DEG C AIR FROM WYOMING NORTHWARD TO/ACROSS THE
CANADIAN PRAIRIES. AT 700 AND 850 HPA...COLDER AIR WAS ADVECTING ACROSS
THE NORTHERN AND CENTRAL PLAINS. AT THE SURFACE, A COLD FRONT WAS PUSHING
ACROSS THE STATE OF KANSAS EARLY THIS MORNING. -SUGDEN
&&
.DISCUSSION...
DAYS 1-2...
TODAY:
THE AFOREMENTIONED MID ATMOSPHERIC LOW WILL SINK SOUTHWARD FROM UTAH
TO THE 4 CORNERS REGION. THE 80-90 KT JET WRAPPING AROUND THIS LOW WILL
PUT WESTERN KANSAS JUST NORTH OF THE LEFT EXIT REGION WITH DYNAMIC LIFT
AND 700 OMEGA DEVELOPING ACROSS THE REGION. IN ADDITION, UPSLOPE 700/850
HPA FLOW WILL PROVIDE ENOUGH LOW TO MID LEVEL LIFT TO PROVIDE THE REGION
WITH LIGHT SNOW SHOWERS TODAY. THE LATEST HRRR (WHICH ONLY GOES OUT
TIL ABOUT 20Z) WAS USED AS A STARTING FOUNDATION FOR SNOW ACCUMULATION.
MUCH OF THE REGION WILL SEE ABOUT 0.5 TO 1.0 INCHES WITH SLIGHTLY MORE
POSSIBLE ACROSS MY NORTHWEST COUNTIES (FLIRTING TO AROUND 2.0 INCHES).
HAVE ADDED BLOWING SNOW BASED OFF UPSTREAM OBSERVATIONS SHOWING A REDUCTION
IN VISIBILITIES ALREADY. OTHERWISE, TODAY WILL BE CLOUDY WITH NORTH
TO NORTHEASTERLY WINDS RUNNING AROUND 20 KT IN THE WAKE OF A COLD FRONT.
WILL HIGHLIGHT THE LIGHT SNOW ACCUMULATIONS/BLOWING SNOW IN THE HWO
BUT THIS WILL BE BELOW ADVISORY CRITERIA SO AM NOT PLANNING TO ISSUE
A WSW RIGHT NOW. MAXIMUM TEMPERATURES WILL BE IN THE UPPER 20S TO LOWER
30S DEG F.
TONIGHT:
PRECIPITATION WILL END THIS EVENING FROM THE NORTHEAST TO THE SOUTHWEST
AS THE MID LEVEL LOW SINKS FURTHER SOUTH. FORECAST SOUNDINGS SHOW QUITE
A BIT OF DRYING LATE TONIGHT INTO TOMORROW MORNING SO I HAVE RAMPED
CLOUD COVER DOWN. WITH CLEARING SKIES AND A SURFACE HIGH PRESSURE CENTER
SLIDING ACROSS KANSAS, A GOOD NIGHT FOR RADIATIONAL COOLING IS EXPECTED.
MINIMUM TEMPERATURES IN THE SINGLE DIGITS DEG F IS EXPECTED ACROSS FAR
WESTERN KANSAS. SLIGHTLY WARMER TEMPERATURES WITH TEENS DEG F ARE EXPECTED
ACROSS SOUTH CENTRAL KANSAS.
FRIDAY/FRIDAY NIGHT:
I HAVE INCREASED TEMPERATURES FRIDAY AS A LEE TROUGH DEVELOPS ACROSS
THE LEE OF THE ROCKIES AND MOVES EAST IN ASSOCIATION WITH THE PASSAGE
OF A WEAK SHORTWAVE TROF TRAVERSING ACROSS THE NORTHERN PLAINS. MAXIMUM
TEMPERATURES SHOULD WARM TO NEAR TO SLIGHTLY ABOVE FREEZING WITH A BIT
OF DOWNSLOPE SOUTHWESTERLY TO WESTERLY SURFACE WINDS. A DRY ATMOSPHERE
WILL LEAD TO FULL INSOLATION ON FRIDAY AS WELL. A BIT OF EROSION OF
THE SNOW FIELD IS POSSIBLE FRIDAY FOR AREAS THAT GET ABOVE FREEZING.
OVERNIGHT LOWS INTO SATURDAY WILL BE SLIGHTLY WARMER WITH THE CONTINUATION
OF A DOWNSLOPE WESTERLY WIND. NO PRECIPITATION IS EXPECTED FRIDAY. -SUGDEN
DAYS 3-7...
THE PERIOD SATURDAY THROUGH WEDNESDAY WILL BE VERY QUIET SENSIBLE WEATHER
WISE WITH NO PRECIPITATION EXPECTED DURING THIS ENTIRE PERIOD. THE PLANETARY
SCALE PATTERN ACROSS THE NORTH PACIFIC INTO NORTH AMERICA WILL BE CHARACTERIZED
BY A LOW WAVE NUMBER/LOW AMPLITUDE WHICH WILL RESULT IN A WARMER-THAN-
AVERAGE PERIOD OF WEATHER ACROSS THE WESTERN PLAINS...IF IT WERE NOT
FOR A FAIRLY HEALTHY SNOW PACK IN PLACE.
THE 19-20 DECEMBER BLIZZARD CAUSED A LARGE SNOWPACK ACROSS SOUTHEASTERN
COLORADO AND WEST-CENTRAL/SOUTHWEST KANSAS WHICH WILL TAKE SEVERAL DAYS
TO DWINDLE DOWN. AS A RESULT...HIGH TEMPERATURE FORECASTING WILL BE
DIFFICULT...AND WILL BE DEPENDENT UPON THE DAILY REDUCTION OF THE SNOWPACK.
AN UPPER RIDGE WILL BUILD OVER THE ROCKIES SATURDAY/SATURDAY NIGHT...WHICH
WILL THEN ERODE AS ZONAL JET FLOW MOVES INTO THE NORTHERN ROCKIES SPAWNING
A DEEP LEE TROUGH FROM ALBERTA SOUTH TO EASTERN COLORADO. THIS LOOKS
LIKE A CLASSIC DOWNSLOPE WARMING SETUP AND IT WOULD APPEAR ON PAPER
THAT THIS DAY WILL BE QUITE WARM AND WILL REALLY KNOCK OUT A GOOD CHUNK
OF WHATEVER REMNANT SNOWPACK THERE IS ACROSS WESTERN DDC FORECAST AREA.
WITH SOME COLLABORATION HAVE INCREASED THE HIGHS A FEW DEGREES OVER
THE ALLBLEND GUIDANCE FOR MONDAY. THIS IS THE ONLY CHANGE MADE AGAINST
THE ALLBLEND GUIDANCE FOR THE MEDIUM RANGE.
IN THE FAR EXTENDED TIME FRAME...AN EXTENDED NORTH PACIFIC JET WILL
MIGRATE EASTWARD DURING THE 27-30 DECEMBER TIME FRAME WITH A HINT AT
RIDGE BUILDING SOMEWHERE BETWEEN 140W AND 120W...WHICH COULD FAVOR DOWNSTREAM
TROUGH DEVELOPMENT OVER THE WESTERN OR CENTRAL CONUS BY THE 30-31 DECEMBER
TIME FRAME. THIS WOULD BE THE EARLIEST TIME FRAME THAT PRECIPITATION
CHANCES COULD ENTER THE PICTURE...BUT THIS IS IN THE DAY 8-10 TIME FRAME
AND IT REMAINS TO BE SEEN HOW THE SYNOPTIC SCALE EVOLVES AS THE EXTENDED
JET APPROACHES THE NORTHEAST PACIFIC. -UMSCHEID
&&
.AVIATION...
FOR THE 06Z TAF ISSUANCE...VFR CIGS AT THE TAF SITES WILL DEGRADE INTO
MVFR/IFR CONDITIONS THROUGH THE EARLY MORNING HOURS. LIGHT SNOW WILL
SPREAD SOUTH ACROSS WESTERN KANSAS FROM THE EARLY MORNING HOURS THROUGH
ABOUT MIDDAY BEFORE MOVING SOUTH OF THE AREA THIS AFTERNOON. OCCASIONAL
MVFR VSBYS IN LIGHT SNOW WILL BE POSSIBLE.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 29 14 33 14 / 50 10 0 0
GCK 28 8 33 12 / 60 20 0 0
EHA 27 10 27 16 / 70 20 0 0
LBL 29 12 31 15 / 60 20 0 0
HYS 30 13 34 14 / 60 10 0 0
P28 33 19 36 21 / 50 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN36/25/25
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
358 AM CST THU DEC 22 2011
.DISCUSSION...
NEAR TERM MODEL SOLUTIONS CONTINUE TO INDICATE AN
ABRUPT END TO THE SNOWFALL AS DRIER AIR AND DIMINISHING FORCING WILL
EFFECTIVELY END SNOW PRODUCTION BEFORE SUNRISE FOR MOST OF THE
FORECAST AREA. THE LONE EXCEPTIONS WILL BE THE FAR SOUTHERN
COUNTIES...WHERE MODEL CONSENSUS WOULD SUGGEST -SN OR FLURRIES UP
THROUGH 15Z TODAY. FLURRIES ALSO MAY BE POSSIBLE ACROSS THE
SAND HILLS THROUGH MID MORNING AS THE 22.05Z HRRR INDICATES CSI
BANDING IN THE WAKE OF THE DEPARTING SYSTEM. CROSS SECTIONS DO
REVEAL A SHORT PERIOD WHERE MOMENTUM LINES RUN PARALLEL TO THE
THETA SURFACES...SO WILL NOT RULE OUT A STRAY FLURRY OR SNOW
SHOWER...BUT GIVEN RECENT RADAR TRENDS AND THE DRYING...FEEL THAT
THE THREAT WILL BE MINIMAL AT BEST. OTHERWISE...CAA AND
SNOW PACK...ALBEIT SLIGHT SNOW PACK...WITH HELP KEEP TEMPERATURES
BELOW AVERAGE THIS AFTERNOON...WITH GENERAL MODEL CONSENSUS
SUGGESTING HIGHS IN THE LOWER 30S. DID UNDERCUT GUIDANCE SLIGHTLY
ACROSS THE WEST...WHERE A SLIGHTLY DEEPER SNOW PACK RESIDES...MID
TO UPPER 20S SHOULD BE FINE. FOR TONIGHT..WESTERLY DOWN SLOPING
FLOW DEVELOPS OVERNIGHT AS CANADIAN HIGH PRESSURE SETTLES ACROSS
THE DEEPER SNOW PACK OF EASTERN COLORADO AND WESTERN
KANSAS/OKLAHOMA. GUIDANCE IS SUGGESTING RATHER COLD TEMPERATURES
ACROSS THE CWA...WITH POSSIBLY SUB ZERO READINGS ACROSS THE FAR
WESTERN ZONES. NOT READY TO LOWER MINS THAT MUCH...ESPECIALLY
SINCE WEAK WAA AND DOWN SLOPE FLOW SHOULD PREVAIL. AS OF
NOW...SINGLE DIGIT LOWS LOOK APPROPRIATE ACROSS THE WESTERN HALF
OF THE CWA...WITH LOW TO MID TEENS ACROSS THE EAST. ON
FRIDAY...RISING HEIGHTS ASSOCIATED WITH SHORTWAVE RIDGING WILL
WORK IN CONCERT WITH DOWN SLOPING FLOW TO PUSH TEMPERATURES UP TO
NEAR CLIMO...WITH HIGHS BACK INTO THE UPPER 30S...POSSIBLY IN THE
LOW 40S FOR THE WARM BIASED LOCATIONS.
FOR THE HOLIDAY WEEKEND AND BEYOND. NORTHWESTERLY FLOW WILL BECOME
ESTABLISHED ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS AS RIDGING
BUILDS ACROSS THE WESTERN CONUS. THE NORTHERN STREAM REMAINS
ACTIVE...WITH INDICATIONS OF SEVERAL SHORTWAVES PUSHING SOUTHEAST
FROM THE CANADIAN ROCKIES TOWARD THE GREAT LAKES REGION...BUT A LACK
OF KINEMATIC FORCING WILL KEEP PRECIPITATION OUT OF THE FORECAST
THROUGH MIDWEEK. AS FOR TEMPERATURES...A GRADUAL WARMING TREND IS
EXPECTED THROUGH EARLY NEXT WEEK. HIGHS SATURDAY AND CHRISTMAS DAY
SHOULD CLIMB ABOVE 40F AS INCREASING THICKNESS BUILDS OVER WESTERN
NEBRASKA. MONDAY APPEARS TO BE THE WARMEST DAY YET...AS H85 TEMPS
FLIRT WITH 10C AND DOWN SLOPING FLOW HELP WARM TEMPS AOA 50F. LOWS
THROUGH THE EXTENDED LOOK TO REMAIN ABOVE SEASONAL NORMS...WITH MID
TEENS AND 20S EXPECTED.
&&
.AVIATION...
MIXED MVFR/VFR LOCAL IFR CONDITIONS WILL RAPIDLY IMPROVE TO VFR FROM
NORTH TO SOUTH THIS MORNING. VFR COULD BE WIDESPREAD BY 12Z AND
CERTAINLY BY 15Z AS PACIFIC HIGH PRESSURE AND DRY AIR AT THE LOWER
LEVELS SWEEPS IN.
VFR IS EXPECTED ALL AREAS 15Z THROUGH 12Z FRIDAY AS HIGH PRESSURE
DRIFTS SOUTH ACROSS KS/COLO AND LOW PRESSURE DEEPENS ACROSS SRN
CANADA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...JACOBS
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
301 AM EST THU DEC 22 2011
.SYNOPSIS...
UNSEASONABLE WARMTH WILL CONTINUE TODAY WITH ONLY A FEW SHOWERS. A
COLD FRONT WILL MOVE ACROSS THE AREA FRIDAY BRINGING WITH IT A
BETTER CHANCE OF SHOWERS. CHRISTMAS EVE WILL BE DRY WITH A WET
CHRISTMAS DAY. NEXT WEEK LOOKS TO BE DRY WITH SEASONABLE TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM THURSDAY...TODAY IS THE FIRST DAY OF WINTER AND WILL
SEE SOME OF THE LOWEST SUN ANGLES (32-33 DEGREES AT SOLAR NOON)...
THE SHORTEST DAY LENGTH (ABOUT 9 HOURS 52 MINUTES)...AND THE LEAST
POTENTIAL SOLAR ENERGY OF THE ENTIRE YEAR. HOWEVER OUR AIRMASS IS
SUBTROPICAL IN ORIGIN AND WILL YIELD HIGH TEMPERATURES MORE TYPICAL
OF MID-APRIL THAN MID-DECEMBER. SOUTH FLOW BETWEEN HIGH PRESSURE
WELL OFFSHORE AND A COLD FRONT SNAKING FROM COASTAL NEW ENGLAND
THROUGH THE SOUTHERN APPALACHIANS WILL CONTINUE TO BRING THIS WARM
AND HUMID AIR INTO THE CAROLINAS THROUGH TONIGHT.
PLENTY OF STRATOCUMULUS BETWEEN 3000-6000 FT AGL WILL MOVE ACROSS
THE AREA TODAY. LOW STRATUS BELOW 600 FT SHOULD AFFECT MAINLY THE
AREA WEST OF I-95 THIS MORNING...BUT EVEN HERE CLOUDS SHOULD BURN
OFF BY MID TO LATE MORNING WITH THE FILTERED SUNSHINE ENOUGH TO
PRODUCE HIGHS IN THE 72-75 RANGE...ABOUT 1-2 DEGREES ABOVE GFS/NAM
MOS CONSENSUS. THE ONLY PORTION OF OUR FORECAST AREA NOT EXPECTED TO
SHARE THE WARMTH TODAY IS THE IMMEDIATE COASTLINE WHERE A SOUTH-
SOUTHWEST (220 DEGREE) WIND IS ONSHORE. THIS INCLUDES AREAS BETWEEN
MYRTLE BEACH AND BALD HEAD ISLAND...PLUS MOST OF THE PENDER COUNTY
BEACHES. HERE COOLER MARINE AIR WILL KEEP TEMPERATURES IN THE 60S
TODAY...ALONG WITH THE POTENTIAL FOR SOME SEA FOG AS DEWPOINTS RISE
IN THE LOWER TO MID 60S THIS AFTERNOON AND EVENING.
COMPARED TO YESTERDAY WE SEE COMPARATIVELY LITTLE POTENTIAL FOR
SHOWERS TODAY DUE TO LACK OF ANY UPPER DISTURBANCES TO PRODUCE LIFT.
CONVECTIVE POTENTIAL DUE TO SURFACE HEATING IS VERY LOW GIVEN THE
SHALLOW MIXED LAYER EXPECTED TO DEVELOP. IF ANY SHOWERS WERE TO
DEVELOP LATER TODAY...THE AREA ALONG AND WEST OF I-95 IS PREFERRED
DUE TO THE RELATIVE PROXIMITY OF AN UPPER DISTURBANCE AFTER 18Z THAT
MOVES THROUGH THE WESTERN CAROLINAS. SHOWER CHANCES WILL INCREASE A
LITTLE MORE LATE THIS EVENING AS A 300 MB JET STREAK MOVES NORTH OF
THE AREA AND CREATES AN AREA OF DIFLUENCE AND INFERRED LIFT ACROSS
THE CENTRAL CAROLINAS. OUR POPS TONIGHT RANGE FROM 20 ALONG THE
COAST TO 40 IN THE LUMBERTON/BENNETTSVILLE AREA...WITH LOWS EXPECTED
TO REMAIN IN THE 59-63 RANGE FOR MOST AREAS.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...PROSPECTS FOR AN APPRECIABLE OR AT LEAST A
"WETTING` RAIN EVENT FOR FRIDAY HAVE TAKEN A STEP BACK WITH THE
LATEST MODEL CYCLES THIS MORNING. COLD FRONT MOVING ACROSS THE
AREA REMAINS ON SCHEDULE BUT ANY MID LEVEL FORCING HAS WEAKENED
WITH A BROAD EXIT REGION OF THE 300MB JET. WE WILL PROBABLY SEE
SEVERAL PATCHES OF LIGHT RAIN SIMILAR TO WEDNESDAY BEFORE 1800 UTC
FRIDAY. CHRISTMAS EVE COULD OFFER A LITTLE SUNSHINE ALTHOUGH WITH
THE PERSISTENT MOISTURE LADEN SOUTHWEST FLOW MID LEVEL SCATTERED
TO BROKEN CEILINGS ARE PROBABLE. TAKING A QUE FROM WEDNESDAYS
EVENTS...LEANED TOWARD THE COOLER MET NUMBERS FOR HIGHS FRIDAY AND
A BLEND SATURDAY AS TEMPERATURES REMAIN ELEVATED FROM SEASONAL
NORMS.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...THE EXTENDED PACKAGE THIS MORNING IS ESSENTIALLY AN
UPDATE OF THE PREVIOUS FORECAST AS THE MEDIUM RANGE MODELS CONTINUE
TO STRUGGLE WITH THE SCENARIO AND TIMING OF PACIFIC ENERGY. THIS
WILL BE THE IMPETUS THAT KICKS OUT WHAT SHOULD BE A SHEARING
SHORTWAVE FROM THE SEEMINGLY PERSISTENT TROUGH ACROSS THE SOUTHWEST.
THERE IS SOME CONSENSUS BUILDING THAT THE SYSTEM WILL BE WEAK AND A
QUICK MOVER. THE FORECAST FOR CHRISTMAS DAY IS ISNT LOOKING GREAT.
DID INCREMENTALLY INCREASE POPS TO REFLECT A SLIGHT INCREASE IN
CONFIDENCE. OTHERWISE NO OTHER CHANGES. DIDNT WANT TO GET INTO
TRYING TO RESOLVE ANY ISSUES FOR LATE IN THE PERIOD WHEN THE MODELS
CONTINUE TO STRUGGLE WITH EARLIER FEATURES.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
AS OF 06Z...HIGH UNCERTAINTY EXISTS WITH REGARDS TO CEILING HEIGHTS
THROUGH DAYBREAK. MOISTURE IS SUFFICIENT ENOUGH TO ALLOW IFR
CEILINGS TO FORM SOMETIME AFTER 09Z...BUT ONLY ACROSS THE FLORENCE
AND LUMBERTON VICINITY WHERE SURFACE WINDS WILL BE LIGHTER AND
TEMPERATURES ARE ALREADY COOLER AND CLOSER TO SATURATION. THIS IS
ALSO WHAT THE LATEST HRRR AVIATION FORECAST FIELDS ARE SHOWING.
PREDOMINANT VISIBILITIES WILL LIKELY REMAIN ABOVE 3SM AS THE WINDS
JUST ABOVE THE SURFACE WILL AVERAGE 15 KTS OR MORE. ANY EARLY IFR
WILL IMPROVE TO MVFR BY MID MORNING...BECOMING VFR IN THE
AFTERNOON...ALTHOUGH A STRATOCUMULUS CEILING WILL LIKELY REMAIN.
CONTINUED SOUTHWEST FLOW...INCREASING TO 10 KTS BY MID MORNING.
EXTENDED OUTLOOK...SCATTERED SHOWERS WITH ASSOCIATED RESTRICTIONS
LIKELY FRIDAY. IMPROVING CONDITIONS SATURDAY...WITH ANOTHER WEATHER
SYSTEM ON SUNDAY. VFR MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM THURSDAY...HIGH PRESSURE WELL OFFSHORE IS PUMPING A
WARM AND HUMID AIRMASS NORTHWARD ALONG THE CAROLINA COASTLINE. A
COLD FRONT EXTENDING FROM COASTAL NEW ENGLAND SOUTH INTO THE WESTERN
CAROLINAS WILL MOVE SLOWLY EASTWARD THROUGH TONIGHT...REMAINING
INLAND. A PERIOD OF MODERATE SOUTH-SOUTHWESTERLY FLOW EARLY THIS
EVENING HAS BUILT SEAS TO AS HIGH AS 6 FT AT THE FRYING PAN SHOALS
BUOY...AND 4 FT AT THE NEARSHORE WRIGHTSVILLE BEACH BUOY. MODELS
SHOW WIND SPEEDS DIMINISHING LATER THIS MORNING WITH SEAS EXPECTED
TO COME DOWN BY ABOUT ONE-QUARTER. WINDS ARE HOWEVER EXPECTED TO
PICK BACK UP THIS EVENING WITH THE POTENTIAL OF A FEW 6 FT SEAS
DEVELOPING WITHIN 20 MILES OF SHORE...PARTICULARLY ACROSS THE NORTH
CAROLINA WATERS. CONDITIONS ARE MARGINAL FOR A SMALL CRAFT ADVISORY
ALONG FRYING PAN SHOALS OVERNIGHT...BUT FOR NOW WE WILL STICK WITH
15-20 KT WINDS AND 4-5 FT SEAS IN THE FORECAST.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...BIG STORY WILL BE THE WIND SHIFT FOR FRIDAY
AFTERNOON AS THE FRONT MOVES ACROSS THE WATERS. WINDS VEER FROM
SOUTHWEST TO NORTHEAST. WITHOUT ANY SIGNIFICANT COLD AIR
ADVECTION...SPEEDS WILL BE LIMITED TO A MAX OF 15-20 KNOTS MAINLY
FOR A FEW HOURS SATURDAY AFTERNOON. HIGH PRESSURE WEAKENS AND
SETTLES SOUTH BY EARLY SUNDAY ALLOWING FOR A MORE EASTERLY FLOW. THE
LATEST SWAN IS ADVERTISING 3-5 FEET FRIDAY DROPPING OT 2-4 FEET
SATURDAY.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 300 AM THURSDAY...PRESSURE PATTERN BECOMES VERY DIFFUSE AS A
MID LEVEL SYSTEM ROLLS ACROSS SUNDAY. IN THE WAKE OF THIS SYSTEM A
WEST TO NORTHWEST FLOW DEVELOPS AS HIGH PRESSURE BUILDS IN FROM
THE MISSISSIPPI VALLEY. WIND SPEEDS INCREASE TO NEAR 20 KNOTS EARLY
MONDAY. WITH THE OFFSHORE FLOW EXPECT SEAS OF 2-4 FEET WITH THE
HIGHER VALUES FURTHER ACROSS THE OUTER WATERS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...TRA
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...DL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1230 AM EST THU DEC 22 2011
.SYNOPSIS...
A SERIES OF LOW PRESSURE SYSTEMS PASSING WEST AND NORTH OF THE AREA
WILL MAINTAIN A MILD PATTERN WITH SCATTERED SHOWERS THROUGH THE
WEEK. A COLD FRONT IS EXPECTED TO CROSS THE REGION LATE
FRIDAY...WITH COOL HIGH PRESSURE BUILDING FROM THE WEST THIS
WEEKEND. FAIR AND DRY CONDITIONS ARE EXPECTED INTO EARLY NEXT WEEK.
UNSETTLED CONDITIONS MAY RETURN BY THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 AM THURSDAY...VERY FEW CHANGES NEEDED ON THIS EARLY
MORNING FORECAST UPDATE. AN ANOMALOUSLY WARM AND HUMID AIRMASS (FOR
THE FIRST DAY OF WINTER) COVERS THE EASTERN CAROLINAS. SCATTERED TO
BROKEN MID AND HIGH LEVEL CLOUD COVER EXISTS ACROSS THE AREA...BUT
ENOUGH BREAKS ARE SHOWING UP ON INFRARED SATELLITE IMAGERY ACROSS
EASTERN SOUTH CAROLINA THAT WE MAY SEE TEMPERATURES FALL DESPITE A
STEADY 5-10 MPH SOUTH WIND. SOME LOWER CLOUDS MAY DEVELOP ESPECIALLY
ACROSS THE PEE DEE AND LUMBERTON AREA BEFORE DAYBREAK DUE TO
RADIATIONAL COOLING WITHIN THE HUMID AIRMASS. SHOWER ACTIVITY HAS
NEARLY DISSIPATED AND WE ARE EXPECTING ONLY A SLIGHT CHANCE OF ANY
ADDITIONAL SHOWER DEVELOPMENT OVERNIGHT.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...MOIST AND MILD SW COLUMN WIND FLOW WILL
SUSTAIN A CHANCE OF SHOWERS THROUGH THE SHORT TERM PERIOD...AS A
SERIES OF WEAK IMPULSES ALOFT GENERATE ENOUGH BUOYANCY TO SUSTAIN
LIGHT AND MODERATE SHOWERS THURSDAY AND FRIDAY. TIME-HGT SECTIONS
DEPICT A BIT OF DRYING ALOFT FRIDAY AFTERNOON AS DRIER WESTERLY
WINDS ARRIVE BEHIND A COLD FRONT WHICH PUSHES OFF THE COAST THEN.
RAIN CHANCES HOWEVER WERE CARRIED INTO FRIDAY NIGHT AND OVERNIGHT
INTO EARLY SATURDAY...WITH COOL OVERRUNNING POTENTIAL BEHIND THE
COLD FRONT. CONSENSUS HAS BECOME MORE SOLID AMONG GFS/NAM/EURO MODEL
TIMING...BRINGING THE FRONT THROUGH OUR FORECAST AREA FROM MIDDAY
FRIDAY FAR INTERIOR...BEFORE CHUGGING OFF THE COAST BY OR AROUND
NIGHTFALL FRIDAY LATE AFTERNOON.
CLEARLY WE WILL EXPERIENCE WELL ABOVE NORMAL TEMPERATURES IN THE
BALMY WARM SECTOR REGIME...WITH OVERNIGHT LOWS REPRESENTING WHAT
SHOULD BE NEAR NORMAL TEMPS FOR MAXIMUMS! THURSDAY THE MILDEST DAY
WITH WIDESPREAD READINGS IN THE 70S AWAY FROM THE IMMEDIATE COAST.
TEMPS DAYBREAK THURSDAY WILL HAVE A GOOD HEAD-START...ONLY DIPPING
TO AROUND 60. SOME COOL ADVECTION SHOULD ARRIVE LATE FRIDAY NIGHT
BUT WILL BE TEMPERED BY WINDS AND CLOUDS...BUT WILL SHOOT FOR A
42-51 DEGREE RANGE DAYBREAK SATURDAY...COOLEST NORTH AND WESTERN
ZONES...AND MILDEST ALONG THE SC COAST...WHERE THE FRONT WILL
FINALLY CLEAR OUR WARNING AREA. NO TSTMS INSERTED...AS INSTABILITY
APPEARS MEAGER.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 3 PM WEDNESDAY...THE 12Z CANADIAN/GFS ALONG WITH THE 00Z ECMWF
WERE SHOWING SOME SIMILARITIES BUT THE 12Z ECMWF HAS INTRODUCED MORE
UNCERTAINTY...ESPECIALLY LATE IN THE PERIOD. COLD FRONT OFF THE
COAST AT THE START OF THE PERIOD IS NOW PUSHED FARTHER SOUTH AND
EAST SAT AS HIGH PRESSURE OVER WESTERN KY EXTENDING EAST. HIGH
CONTINUES TO TRANSLATE EAST SAT NIGHT INTO SUN AS WEAK SHORTWAVE
EMERGES FROM THE WESTERN GULF OF MEXICO. WAVE INDUCES A SURFACE LOW
ALONG THE FRONT...STALLED ALONG THE GULF COAST. THIS LOW PASSES
OVER OR JUST EAST OF THE AREA SUN INTO SUN NIGHT...BRINGING PERHAPS
THE BEST CHANCE OF PRECIP FOR THE PERIOD. THUS HIGHEST POP FORECAST
IS ON SUN. GUIDANCE IS STILL HAVING TROUBLE RESOLVING THIS SHORTWAVE
SO TIMING AND LOCATION OF THE SURFACE FEATURE REMAIN IN QUESTION.
WED AND WED NIGHT THE FORECAST BECOMES MORE COMPLICATED. MEDIUM
RANGE GUIDANCE SHOWS ANOTHER WAVE EMERGING FROM THE GULF OF MEXICO
ON WED. HOWEVER LOCATION AND STRENGTH OF THE FEATURE VARIES
CONSIDERABLY. CONFIDENCE IS QUITE LOW AND FORECAST IS A BLEND OF THE
12Z GFS AND 00Z ECMWF WHICH RESULTS IN ANOTHER WEAK LOW AND
ASSOCIATED SHORTWAVE PASSING OFF THE SOUTHEAST COAST.
TEMPERATURES NEAR TO ABOVE CLIMO THROUGH THE PERIOD. LOWS WILL BE A
LITTLE MORE ABOVE THAN THE HIGHS...ESPECIALLY EARLY IN THE PERIOD.
SAT NIGHT LOWS COULD END UP CLOSE TO 10 DEGREES ABOVE CLIMO.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 06Z...HIGH UNCERTAINTY EXISTS WITH REGARDS TO CEILING HEIGHTS
THROUGH DAYBREAK. MOISTURE IS SUFFICIENT ENOUGH TO ALLOW IFR
CEILINGS TO FORM SOMETIME AFTER 09Z...BUT ONLY ACROSS THE FLORENCE
AND LUMBERTON VICINITY WHERE SURFACE WINDS WILL BE LIGHTER AND
TEMPERATURES ARE ALREADY COOLER AND CLOSER TO SATURATION. THIS IS
ALSO WHAT THE LATEST HRRR AVIATION FORECAST FIELDS ARE SHOWING.
PREDOMINANT VISIBILITIES WILL LIKELY REMAIN ABOVE 3SM AS THE WINDS
JUST ABOVE THE SURFACE WILL AVERAGE 15 KTS OR MORE. ANY EARLY IFR
WILL IMPROVE TO MVFR BY MID MORNING...BECOMING VFR IN THE
AFTERNOON...ALTHOUGH A STRATOCUMULUS CEILING WILL LIKELY REMAIN.
CONTINUED SOUTHWEST FLOW...INCREASING TO 10 KTS BY MID MORNING.
EXTENDED OUTLOOK...SCATTERED SHOWERS WITH ASSOCIATED RESTRICTIONS
LIKELY FRIDAY. IMPROVING CONDITIONS SATURDAY...WITH ANOTHER WEATHER
SYSTEM ON SUNDAY. VFR MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 AM THURSDAY...NO CHANGES NEEDED ON THIS EARLY MORNING
UPDATE. PREVIOUS DISCUSSION FROM 930 AM FOLLOWS...
SOMEWHAT PINCHED SFC PRESSURE GRADIENT ACROSS THE WATERS TO RELAX
SOME OVERNIGHT AS AN UPPER S/W TROF DEPARTS TO THE NE THIS EVENING.
THE COLD FRONT TO REMAIN NORTHWEST OF THE AREA OVERNIGHT KEEPING
WINDS FROM THE S-SW. WIND SPEEDS SHOULD DIMINISH BY ATLEAST 5 KT
OVERNIGHT. LATEST BUOY REPORTS INDICATE WINDS AND SEAS WELL BELOW
SCA THRESHOLDS WHERE SSTS ARE IN THE 50S...IN FACT EVEN BELOW SCEC
THRESHOLDS. WILL HOWEVER CONTINUE SCEC CONDITIONS FOR THE ILM NC
WATERS TO ACCOUNT FOR THE OUTER WATERS OFF CAPE FEAR EXHIBITING HIER
WATER TEMPS...RESULTING IN SW-15-20 KT WINDS AND 5 FT SEAS DURING
THIS EVENING. WITH A RATHER DIFFUSE BUOY NETWORK...DIFFICULT TO
JUDGE/GAGE JUST HOW MUCH OF THOSE HIGHER SEAS OFFSHORE ARE BLEEDING
INTO THE COASTAL WATERS.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...WE MAY NEED A SMALL CRAFT ADVISORY FOR THU
NIGHT ALTHOUGH IT APPEARS MARGINAL OR LOW-END. BUT 4-6 FOOT SEAS
SHOULD BE EXPECTED LATE THURSDAY AND HIGHEST OFFSHORE. THE PRIMARY
WAVE ENERGY THU AND FRI WILL BE S WAVES WITH INTERVALS OF 6-7
SECONDS. AS WINDS GO NE LATE FRI/EARLY SAT...WE WILL SEE ENE WAVES
ENTER THE PICTURE AS THE S WAVES FADE A BIT. STRONGEST WINDS
THURSDAY NIGHT AND FRIDAY MORNING...AND THIS REPRESENTS THE BEST
CHANCE FOR AN ADVISORY.
LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 PM WEDNESDAY...NORTH TO NORTHEAST FLOW WILL CONTINUE
THROUGH THE PERIOD. A COLD FRONT OFF THE COAST AT THE START OF THE
PERIOD WILL PUSH FARTHER SOUTH AND EAST SAT AS HIGH PRESSURE BUILDS
EAST. WEAK SURFACE LOW WILL TRACK ALONG THE BOUNDARY SUN WITH FLOW
FIRST BECOMING MORE EASTERLY AND THE BACKING TO NORTHWEST AS THE LOW
PASSES. NORTHWEST FLOW SUN NIGHT INTO MON WILL VEER TO
NORTH-NORTHEAST DURING MON AS HIGH PRESSURE BUILDS BACK IN FROM THE
WEST. GRADIENT WILL REMAIN RELATIVELY SLACK THROUGH THE
PERIOD...KEEPING SPEEDS 10 TO 15 KT EXCEPT AT THE START OF THE
PERIOD WHERE WANING COLD ADVECTION MAY RESULT IN NORTHEAST WINDS OF
15 TO 20 KT. SEAS START OUT 3 TO 5 FT BUT SUBSIDE TO 2 TO 4 FT BY
SUN.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...COLBY
LONG TERM...III
AVIATION...HDL/TRA
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1050 PM CST WED DEC 21 2011
.DISCUSSION.../ISSUED AT 925 PM CST...
MODEL AND RADAR DATA CONTINUE TO SHOW AN EARLIER AND FASTER DECREASE
IN THE LIGHT SNOW FROM THE NORTH THAN WE HAD BEEN GOING FOR EARLIER.
EVEN IN OUR SOUTHEAST CORNER PRECIPITATION SHOULD MOVE OUT BY 3 AM
IF NOW SOONER. CERTAINLY NOTHING LEFT FOR THURSDAY. EARLIER GFS AND
NEW NAM/NAM12 HAVE A BETTER HANDLE ON THE PRECIPITATION THAN THE
SHORT TERM MODELS RUC AND HRRR. BETTER COOLING STARTING FROM THE
NORTH THIS EVENING SO EARLIER FORECAST LOW TEMPERATURES LOOK OK OR
NOW THOUGH THEY COULD GET A LITTLE COLDER AROUND SUNRISE WITH FASTER
CLEARING. / WILLIAMS
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
LIGHT SNOW AND FLURRIES WILL PERSIST LATE THIS EVENING SOUTH OF A
YANKTON TO SPENCER IA LINE...GRADUALLY SHIFTING SOUTH SOUTHEAST WARD
THROUGH AROUND 12Z. MVFR VISIBILITY AND CEILINGS WILL ACCOMPANY THE
LIGHT SNOWFALL...BUT SHOULD IMPROVE TO VFR SHORTLY AFTER SNOWFALL
ENDS AS DRIER AIR WILL START WORKS INTO THE AREA. FOG PRODUCT
SATELLITE SHOWS A LONG AND NARROW STREAM OF STRATUS TRACKING
SOUTHWARD FROM SOUTHERN MANITOBA INTO NORTHEAST SD. EXPECT LOW END
VFR CEILINGS WITH THIS...BUT A BRIEF DROP INTO MVFR IS POSSIBLE
THROUGH AT LEAST 12Z.
&&
.PREV DISCUSSION.../ISSUED AT 300 PM CST/
UPPER LEVEL LOW PRESSURE CONTINUES TO SAG SOUTH ACROSS THE ROCKIES
THIS AFTERNOON. A DECENT JET STREAK WILL SPREAD ACROSS THE NORTHERN
PLAINS...WHICH WILL INTERACT WITH A WEAK BOUNDARY IN THE MID LEVELS.
REALLY NOT MUCH LOW LEVEL MOISTURE AND INSTABILITY NOT PRESENT SO
ONLY EXPECTING MINOR AMOUNTS OF ACCUMULATION. THE BEST CHANCE TO GET
SOMETHING CLOSER TO A HALF AN INCH OR SO WILL BE ALONG THE MISSOURI
RIVER VALLEY INTO SOUTHERN NORTHWEST IOWA...WITH THE BEST CHANCE
EARLY THIS EVENING. DRIER AND COLDER AIR WILL WORK IN BEHIND THIS
SYSTEM WITH NORTH WINDS EXPECTED TO BE ABOUT 10 TO 20 MPH THROUGH
THE NIGHT INTO THURSDAY. DID LOWER LOWS JUST A TOUCH TONIGHT IN THE
FAR NORTH WHERE SOME CLEARING WILL BE POSSIBLE LATE...BUT REMAINED
CLOSEST TO THE CONSRAW OUTPUT WHICH TENDS TO PERFORM BETTER ON
WIND/CLOUDY NIGHTS.
CLOUDS WILL DECREASE FROM NORTH TO SOUTH THROUGH THE MORNING INTO
THE AFTERNOON ON THURSDAY AS WILL A BREEZY MORNING NORTHWEST WIND.
FAIRLY COLD 925MB TEMPERATURES FROM AROUND -6 TO -8 DEGREES C DO
SUPPORT HIGHS FROM NEAR 32 WEST TO THE UPPER 20S IN THE EAST...AND
WILL GO CLOSE TO THIS IN THE FORECAST. THIS COMES IN A COUPLE OF
DEGREES WARMER THAN THE CONSALL OUTPUT WHICH IS GOOD SINCE THE GEM
AND GFS...BOTH PART OF THE CONSALL...ARE TOO COLD AND HAVE BEEN
RUNNING A 3 TO 6 DEGREE COLD BIAS ON HIGHS FOR THE PAST 20 TO 30
DAYS. /08
FOR THE REST OF THE SHORTER RANGE...A MILD NORTHWEST FLOW ALOFT
REMAINS IN THIS AREA WITH THE SPLIT FLOW JET REGIME CONTINUING. WITH
THE UPPER FLOW COMING OUT OF SOUTHWEST CANADA...IT WILL BE A MILD
FLOW WITH SURFACE WINDS GENERALLY FROM A WESTERLY DIRECTION ALLOWING
FOR PRIME MIXING. GIVEN THE LATEST MODEL CONSENSUS OF 925MB
TEMPERATURES...SEE ABSOLUTELY NO REASON WHY GOING WITH THE WARMEST
GUIDANCE READINGS IS NOT A GOOD IDEA. THE LOW LYING LOCATIONS MAY
BOTTOM OUT A LITTLE THURSDAY NIGHT...BUT OTHERWISE BLENDING THE WARM
BIAS CORRECTED GUIDANCE READINGS WITH THE EVEN WARMER ECMWF NUMBERS
SEEMED PRUDENT.
IN THE EXTENDED SATURDAY NIGHT THROUGH WEDNESDAY...DRY WEATHER WILL
VERY LIKELY CONTINUE WITH THE SAME IDEA CONTINUING. THE 925MB
TEMPERATURES CONTINUE TO BE VERY WARM MEANING THAT GOING WITH THE
WARMEST GUIDANCE READINGS OF BIAS CORRECTED NUMBERS AND ECMWF VALUES
ARE PROBABLY THE BEST WAY TO GO. THE GFS AND GEM VALUES HAVE BEEN
RUNNING VERY COOL LATELY AND SHOULD BE DISCOUNTED.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS AUSTIN/SAN ANTONIO TX
1148 PM CST WED DEC 21 2011
.AVIATION...
UPPER LEVEL DISTURBANCE CURRENTLY CROSSING THE REGION AND SHOULD
MAKE STEADY PROGRESS EAST OVERNIGHT AND INTO EARLY THURSDAY
MORNING. LARGE AREA OF RAIN WITH EMBEDDED THUNDERSTORMS CONTINUES
TO SHIFT TO THE EAST WITH THE PRECIPITATION MOVING NORTHEAST. MVFR
CEILINGS AND VISIBILITIES EXPECTED TO CONTINUE IN AREAS OF RAIN
AND FOG. PRECIPITATION WILL END FROM WEST TO EAST BETWEEN 12Z-14Z.
AFTER 14Z VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD.
WINDS OVERNIGHT WILL BE N-NE AT SPEEDS LESS THAN 10 KTS. KDRT WILL
SEE VFR CONDITIONS WITH EAST WIND LESS THAN 10 KTS BECOMING W-NW
AFTER 12Z. COLD FRONT WILL BEGIN TO IMPACT THE REGION THURSDAY
EVENING. CURRENT THINKING IS FOR A WIND SHIFT TO THE N AT KDRT AND
KAUS AROUND 01Z-03Z AND KSAT AND KSSF 04Z-06Z.
.PREV DISCUSSION... /ISSUED 913 PM CST WED DEC 21 2011/
UPDATE...
RADAR SHOWS BACK EDGE OF PRECIPITATION GENERALLY ALONG A TELEGRAPH
TO QUEMADO LINE MOVING LITTLE. A WIDESPREAD AREA OF MOSTLY LIGHT
RAIN EXTENDS FROM THE MIDDLE RIO GRANDE PLAINS NORTHEAST TO
ENCOMPASS MUCH OF THE HILL COUNTRY AND ADJACENT PORTIONS OF SOUTH
CENTRAL TEXAS LATE THIS EVENING. THE NEW RUC SHORT TERM MODEL RUN
THIS EVENING SHOWS THE UPPER TROUGH PUSHING INTO FAR WESTERN
PORTIONS OF THE CWA (VAL VERDE COUNTY) SHORTLY AFTER MIDNIGHT...
THEN ACCELERATING EASTWARD OVERNIGHT AS IT WEAKENS. THE CURRENT
WIDESPREAD AREA OF LIGHT RAIN WILL CONTINUE TO SPREAD EAST AND BY
3 AM SHOULD ENCOMPASS ALL OF THE EASTERN HALF OF SOUTH CENTRAL
TEXAS WITH RAINS ENDING OVER THE HILL COUNTRY. RAINS SHOULD BE
ENDING OVER ALL OF THE AREA FROM THE WEST BY LATE MORNING. IT
SHOULD REMAIN LIGHT AND DUE TO THE WIDESPREAD AREA...ISOLATED
THUNDERSTORMS AT BEST ARE EXPECTED. GRIDS WERE READJUSTED ACCORDING
TO CURRENT RADAR AND SATELLITE TRENDS.
PREV DISCUSSION... /ISSUED 545 PM CST WED DEC 21 2011/
AVIATION...
VFR CONDITIONS WILL DETERIORATE QUICKLY AS UPPER LEVEL LOW IS
CURRENTLY GENERATING LIGHT RAIN...SHOWERS AND ISOLATED THUNDERSTORMS
ACROSS MEXICO AND ALONG THE RIO GRANDE. THIS PRECIPITATION WILL
SPREAD EAST AND NORTHEAST QUICKLY THROUGH 06Z. MVFR CEILINGS AND
RAIN WILL DEVELOP FROM WEST TO EAST THROUGH 05Z. THUNDERSTORMS ARE
POSSIBLE...MAINLY ALONG AND EAST OF I-35 BETWEEN 05Z-12Z. SMALL
HAIL WILL BE POSSIBLE WITH THE STRONGEST STORMS...BUT COVERAGE AND
PROBABILITIES ARE BOTH LOW...SO NOT MENTIONED IN THE TERMINAL
FORECAST. EXPECTED IMPROVEMENTS TO VFR CONDITIONS AFTER 13Z-15Z.
KDRT EXPECTED TO REMAIN VFR WITH LIGHT RAIN AND SHOWERS. WINDS ARE
EXPECTED TO BE VARIABLE IN DIRECTION...BUT LESS THAN 10 KNOTS
THROUGH THE FORECAST. FOR THE 30 HOUR TAF SITE...NEXT COLD FRONT
WILL CAUSE A WIND SHIFT TOWARDS THE END OF THE FORECAST PERIOD.
PREV DISCUSSION... /ISSUED 323 PM CST WED DEC 21 2011/
DISCUSSION...
A 500 HPA LOW NEAR THE BIG BEND CONTINUES TO DEVELOP AS IT MOVES
TO THE EAST. INCREASING CLOUDS CONTINUE OVER SOUTH CENTRAL TEXAS
EAST OF THIS WEATHER SYSTEM...AND THIS WILL CONTINUE THROUGH
TONIGHT. PATCHY AREAS OF LIGHT RAIN AND SHOWERS ARE DEVELOPING
FROM THE WEST...AND WILL MOVE OVER SOUTH CENTRAL TEXAS TONIGHT.
EXPECT OCCASIONAL RAIN OVER SOUTH CENTRAL TEXAS TONIGHT. RAINFALL
AMOUNTS NEAR A TENTH OF AN INCH ARE EXPECTED OVER THE WEST PART OF
THE AREA AND NEAR ONE HALF TO ONE INCH OVER THE EAST PART OF
SOUTH CENTRAL TEXAS TONIGHT. SHOWERS AND ISOLATED THUNDERSTORMS
ARE EXPECTED WITH THE RAIN TONIGHT. WINTER 2011/2012 WILL
OFFICIALLY BEGIN TONIGHT AT 1130 PM CST...AND WILL END AT 1214 AM
CDT ON TUESDAY...MARCH 20...2012...WHEN THE SPRING OF 2012
OFFICIALLY BEGINS.
ON THURSDAY...DECREASING CLOUDS AND RAIN CHANCES ARE STILL EXPECTED
FROM THE WEST IN THE MORNING...WITH A MOSTLY SUNNY TO PARTLY
CLOUDY CONDITIONS EXPECTED TO DEVELOP ON THURSDAY. WILL SHOW HIGHS
IN THE 60S OVER THE HILL COUNTRY AND IN THE UPPER 60S TO NEAR 70
OVER ADJACENT PARTS OF SOUTH CENTRAL TEXAS.
INCREASING CLOUDS ARE EXPECTED THURSDAY NIGHT AND FRIDAY...WITH
A CHANCE OF RAIN OR SHOWERS POSSIBLE FRIDAY NIGHT AND SATURDAY.
COLD CONDITIONS ARE EXPECTED WITH MOSTLY CLOUDY SKIES SATURDAY
AND SATURDAY NIGHT. RAIN CHANCES ARE EXPECTED TO DECREASE FROM THE
WEST SATURDAY NIGHT...FOLLOWED BY PARTLY CLOUDY CONDITIONS ON
SUNDAY...WITH DAYTIME HIGHS IN THE 50S.
A FAST MOVING DISTURBANCE WILL COME ACROSS SOUTH CENTRAL TEXAS
MONDAY...YET EXPECT SCATTERED CLOUDS WITH THIS WEATHER SYSTEM...
FOLLOWED BY MOSTLY SUNNY TO PARTLY CLOUDY CONDITIONS IN THE
DAY AND MOSTLY CLEAR NIGHTS ON TUESDAY AND WEDNESDAY OF NEXT
WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 42 67 42 52 36 / 80 20 - 10 20
AUSTIN BERGSTROM INTL AIRPORT 42 67 39 52 35 / 80 20 - 10 20
NEW BRAUNFELS MUNI AIRPORT 44 68 40 54 35 / 80 20 - 10 20
BURNET MUNI AIRPORT 41 65 38 49 34 / 60 10 - 10 10
DEL RIO INTL AIRPORT 39 66 38 51 35 / 50 - 0 - 20
GEORGETOWN MUNI AIRPORT 42 64 39 50 34 / 80 20 - 10 10
HONDO MUNI AIRPORT 44 70 39 55 36 / 70 10 - 10 30
SAN MARCOS MUNI AIRPORT 44 67 40 54 36 / 80 20 - 10 20
LA GRANGE - FAYETTE REGIONAL 47 66 45 56 39 / 80 40 10 10 20
SAN ANTONIO INTL AIRPORT 45 70 42 55 36 / 80 20 - 10 30
STINSON MUNI AIRPORT 46 70 44 56 38 / 80 20 - 10 30
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...10
SYNOPTIC/GRIDS...02
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1157 PM EST WED DEC 21 2011
.SYNOPSIS...
LOW PRESSURE WILL TRACK EASTWARD ACROSS NEW ENGLAND...DRAGGING A
WEAK COLD FRONT THROUGH THE AREA TONIGHT. THE FRONT WILL THEN
STALL ACROSS NORTHERN NORTH CAROLINA THURSDAY MORNING. A SERIES OF
LOW PRESSURE SYSTEMS WILL TRACK UP ALONG THE FRONT THURSDAY AND
AGAIN ON SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 1000 PM EDT WEDNESDAY...
SFC FRONT GETTING CLOSE TO WRN SLOPES OF APPALACHIANS BUT DRIER
LOW LEVEL AIR HAS MOVED INTO THE MTNS AND LIGHT SW WINDS HAVE KEPT
FOG AND DRIZZLE FROM DEVELOPING. ALL PRECIP HAS MOVED EAST OF FCST
AREA AS WELL. SOME LIGHT SOUTHEAST SFC FLOW ON EAST SIDE OF BLUE
RIDGE IS KEEPING LOW CLOUDS AND FOG BANKED UP AGAINST BLUE RIDGE
IN FAR NW NC INCLUDING FANCY GAP...BUT AS FLOW BEGINS TO TURN MORE
SW AND THEN WEST BEHIND FRONT LATER TONIGHT THIS SHOULD LIFT. AT
THE SAME TIME...COOLER AIR BEHIND FRONT AND LIONGERING LOW LEVEL
MSTR ON GROUND...AND WITH POTENTIAL FOR THINNING OUT OF HIGH
CLOUDS...COULD RESULT IN SOME PATCHY VALLEY FOG. ENDED UP REMOVING
MUCH OF THE PATCHY DRIZZLE FROM PREVIOUS UPDATE...AND REDUCING
AREAS OF FOG...EXCEPT FOR MTN VALLEYS AND CLOSER TO WHERE SFC
FRONTAL POSITION IS EXPECTED TO STALL TOWARD MORNING ACROSS FAR
SOUTHEAST. LEFT A SLIGHT CHC OF A SHOWER DOWN THERE AS WELL.
OVERNIGHT TEMPS ARE TRICKY AS AIR BEHIND FRONT IS COOLER BUT NOT
THAT COOL...AND OVERALL THIS HAS BEEN SLOWING DOWN. ENDED UP
BOOSTING OVERNIGHT MINS A COUPLE DEG BECAUSE OF SLOWER
MOVEMENT...AND NOT DROPPING DEW PTS OFF QUITE AS FAST...BUT STILL
FALLING. ALSO MADE SOME MINOR CHANGES INTO THURSDAY MORNING PER
SLOWER MODEL SOLUTIONS FOR NEXT WAVE MOVING UP ALONG FRONT. RAIN
MAY NOT REACH FAR SW UNTIL MIDDAY...AND THEN PERHAPS NOT UNTIL LATE
AFTERNOON OR EARLY EVENING ACROSS THE NORTHEAST. MID SHIFT MAY
NEED TO SLOW THIS DOWN EVEN MORE.
AS OF 710 PM EST WEDNESDAY...
LIGHT SHOWERS AHEAD OF WEAK FRONT HAVE FADED QUICKLY THIS EVENING
AND ONLY A FEW SPOTTY SHOWERS REMAIN...PRIMARILY EAST OF THE BLUE
RIDGE. HAVE UPDATED POPS ACCORDINGLY. LINGERING LOW LEVEL MSTR
WITH STEADY WINDS ALONG THE RIDGES MAY STILL RESULT IN ENOUGH
SHALLOW LIFT FOR SOME DRIZZLE AS WELL AS PATCHY FOG...SUCH AS
ALONG AND NEAR THE BLUE RIDGE AND HOT SPRINGS VCNTY. MID CLOUDS
THINNING OUT AND WITH PARTIAL CLEARING...COULD BEGIN TO SEE SOME
PATCHY FOG IN VALLEYS AS WELL AS WINDS REMAIN DECOUPLED THERE...SO
HAVE INCLUDED A FAIRLY WIDESPREAD AREA OF PATCHY FOG...WITH AREAS
OF FOG ALONG THE BLUE RIDGE. REMOVED MENTION OF ANY DRIZZLE AFTER
MIDNIGHT AS SHALLOW MOISTURE BEGINS TO DRY OUT SLIGHTLY...BUT WILL
KEEP FOG IN THROUGH OVERNIGHT FOR NOW. ALSO WILL KEEP SLIGHT CHC
SHWRS NEAR WEAK FRONTAL BOUNDARY POSITION LATE TONIGHT OUT IN FAR
SOUTHEAT PIEDMONT...AS SUGGESTED BY LOCAL WRF AND HRRR MODELS.
PREV DISCUSSION AS OF 318 PM EST WEDNESDAY...
A WEAK COLD FRONT WILL PIVOT OVER THE AREA TONIGHT...THEN STALL
ACROSS NORTHERN NORTH CAROLINA. THE RAIN WILL END WEST TO EAST THIS
EVENING. AREAS OF DRIZZLE POSSIBLE ON WESTERN FACING SLOPES AND NEAR
THE FRONT THROUGH EARLY MORNING. CLOUD COVER SHOULD ALSO LINGER WITH
THE FRONT STALLED IN THE VICINITY. SOME CLEARING IS POSSIBLE OVER
THE GREENBRIER VALLEY AND ALLEGHANY HIGHLANDS TONIGHT AS HIGH
PRESSURE TRACKS EASTWARD. IF CLEARING IS PRONOUNCED ENOUGH...PATCHY
DENSE FOG COULD DEVELOP TOWARD SUNRISE.
MARITIME AIR BEHIND THE FRONT WILL KEEP TEMPERATURES MILD AND ABOVE
NORMAL.
WINTER SOLSTICE TO BEGIN TONIGHT AT 530Z/1230 AM.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
AS OF 320 PM EST WEDNESDAY...
NEXT IN SERIES OF SOUTHERN STREAM SHORT WAVES EXPECTED TO LIFT
NORTHEAST OUT OF THE SOUTHERN PLAINS AND GULF COAST STATES INTO THE
MID APPALACHIAN AND MID ATLANTIC STATES THURSDAY INTO THURSDAY
NIGHT...TO BE FOLLOWED BY SLIGHTLY COOLER AND DRIER AIR ON THE
BACKSIDE OF THE SYSTEM LATER THURSDAY NIGHT INTO SATURDAY.
ABUNDANT MID AND HIGH LEVEL CLOUDS STREAMING NORTHEAST IN ADVANCE OF
THE SYSTEM SHOULD ASSURE A MOSTLY CLOUDY TO CLOUDY START IN MOST
LOCATIONS ON THURSDAY...WITH THREAT OF PRECIPITATION INCREASING AS
THE DAY PROGRESSES FROM SOUTH TO NORTH AS BROAD UPWARD VERTICAL
MOTIONS FIELDS FROM STRONG MOISTURE TRANSPORT AND INCREASING
ISENTROPIC LIFT IN 850-600 MILLIBAR LAYER COMBINE WITH DIFFERENTIAL
POSITIVE VORTICITY ADVECTION AND UPPER DILUENT FIELD WITH APPROACH
OF RIGHT ENTRANCE REGION OF UPPER JET MAX. EXPECT TO SEE A GOOD
DRENCHING RAIN THROUGHOUT THE ENTIRE BLACKSBURG FORECAST AREA BY
DAYS END...CONTINUING THROUGH THE EVENING HOURS BEFORE BEGINNING TO
TAPER OFF FROM WITH WEST DURING THE EARNING MORNING HOURS ON FRIDAY
WITH PASSAGE OF COOL FRONT. AT THE PRESENT TIME...TOTAL RAINFALL
AMOUNTS FROM THIS SYSTEM ARE NOT EXPECTED TO BE EXCESSIVE...
GENERALLY IN THE ONE-HALF TO ONE-INCH RANGE.
DOWNSLOPING WINDS EAST OF THE BLUE RIDGE SHOULD ALLOW FOR DRY AND
MILD WEATHER ACROSS THE PIEDMONT FRIDAY INTO SATURDAY...ALTHOUGH
SOUTHWESTERLY FLOW ALOFT WILL MAINTAIN AT LEAST SOME PARTIAL MID AND
HIGH LEVEL CLOUD COVER. WEST OF THE BLUE RIDGE...COOL ADVECTION
UPSLOPING WINDS SHOULD MAINTAIN LOWER LEVEL CLOUDS FOR MUCH OF THE
PERIOD...WITH PERHAPS EVEN SOME SPOTTY SHOWERS OR FLURRIES ACROSS
THE PREFERRED HIGHER WEST FACING SLOPES INTO FRIDAY NIGHT.
MOS GUIDANCE THROUGH THE PERIOD QUITE CONSISTENT AND GENERALLY
ACCEPTED EXCLUDING NEED TO SUBTLY TWEAK SOME TEMPERATURES TO REFLECT
LOCAL CLIMATOLOGICAL INFLUENCES.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 330 PM EST WEDNESDAY...
COMPLICATED WEATHER PATTERN IN THE LONG TERM. FORECAST IS HEAVILY
DEPENDENT ON THE EVOLUTION OF A CLOSED UPPER LEVEL LOW THAT IS
CURRENTLY DROPPING INTO THE SOUTHWESTERN PART OF THE COUNTRY. HOW
QUICKLY AND HOW MUCH OF THIS ENERGY EJECTS NORTHEAST WILL PLAY A
MAJOR FACTOR IN OUR WEATHER CHRISTMAS DAY INTO EARLY NEXT WEEK. THE
STRENGTH OF A NORTHERN STREAM WAVE FORECAST TO MOVE INTO THE
NORTHEAST WILL ALSO PLAY A BIG ROLE.
ECMWF AND GFS CONTINUE TO EJECT SOME OF THE ENERGY OVER THE
SOUTHWESTERN STATES INTO OUR REGION CHRISTMAS DAY. HOWEVER THE
AMOUNT OF ENERGY EJECTED CONTINUES TO TREND DOWN...AND THE 12Z GFS
ENSEMBLES HAVE ALSO TRENDED DRY ON CHRISTMAS DAY. MODELS ARE ALSO
TRENDING STRONGER WITH THE NORTHERN STREAM ENERGY...WHICH WOULD
EFFECTIVELY PUSH ANY WAVE FURTHER SOUTH ON CHRISTMAS DAY. BUT JUST
HOW MUCH THIS NORTHERN STREAM CAN SUPPRESS THE SOUTHEAST RIDGE IS
STILL IN QUESTION. GIVEN THE PERSISTENCE OF THE SOUTHEAST RIDGE THIS
MONTH...NOT READY TO GO COMPLETELY WITH THE SOUTHERN SOLUTION. BUT
GIVEN LATEST ECMWF TREND OF PUSHING THE WAVE SOUTH...AND 12Z GFS
ENSEMBLE MEAN KEEPING US DRY...HAVE TRENDED TOWARD THE SOUTHERN
SOLUTION. THIS WOULD KEEP THE BEST CHANCE OF RAIN NEAR THE NC/VA
BORDER AND POINTS SOUTH...WITH DECREASING CHANCES TO THE NORTH.
ENOUGH COLD AIR MAY BE PRESENT FOR SOME SNOW ON THE FAR NORTHERN
FRINGE OF THE PRECIP SHIELD NORTH OF ROUTE 460...HOWEVER THIS IS
STILL A LOW PROBABILITY EVENT AND NO ACCUMULATIONS EXPECTED AT THIS
TIME.
EXPECT A BRIEF DRY PERIOD AND SHOT OF COLD AIR BEHIND THIS SYSTEM ON
MONDAY. HOWEVER MODEL DIFFERENCES BEGIN TO INCREASE AGAIN BY
TUESDAY. THE REST OF THE ENERGY ASSOCIATED WITH THE CLOSED SOUTHWEST
LOW SHOULD FINALLY EJECT NORTHEASTWARD MONDAY NIGHT INTO TUESDAY.
LAST 2 RUNS OF THE ECMWF AND ABOUT HALF THE GFS ENSEMBLES PUSH THIS
WAVE TO OUR NORTH TUESDAY AND TUESDAY NIGHT BRINGING MORE RAIN TO
THE REGION. GIVEN THE CONSISTENCY OF THE ECMWF SOLUTION...AND THE GFS
ENSEMBLES COMING ON BOARD...HAVE TRENDED THE FORECAST TOWARDS THIS
SOLUTION. ECMWF HAS SOME LOW LEVEL COLD AIR LOCKED IN AHEAD OF THIS
SYSTEM...SO VERBATIM IT WOULD HAVE SOME SLEET OR FREEZING RAIN IN
THE ALLEGHANY HIGHLANDS. HOWEVER THIS IS A LOW PROBABILITY
EVENT...BUT WILL BE MONITORED IN THE COMING DAYS.
WENT CLOSE TO HPC GUIDANCE...TRENDED A BIT TOWARD THE ECMWF...FOR
TEMPERATURES THIS PERIOD. THIS RESULTS IN TEMPERATURES AROUND
AVERAGE...HIGHS GENERALLY IN THE 40S WEST AND AROUND 50 EAST...AND
LOWS IN THE 20S TO AROUND 30. COLDEST DAYS LOOK TO BE MONDAY BEHIND
THE FIRST SYSTEM...AND THEN AGAIN ON WEDNESDAY BEHIND THE POTENTIAL
SECOND SYSTEM.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 1155 PM EST WEDNESDAY...
CIGS HAVE LIFTED TO VFR IN WEST WITH DRYING CONDITIONS AND SW FLOW
AS WEAK FRONT IS IN THE PROCESS OF JUMPING ACROSS THE APPALACHIANS
INTO THE PIEDMONT...WHERE SOME MVFR CIGS STILL EXIST. BREAKS IN
CLOUDS IN THE WEST COULD STILL RESULT IN SOME VALLEY FOG LATE
TONIGHT BUT AS DEW PTS CONTINUE TO DRY CURRENT THINKING IS WILL
BARELY GET TO IFR VSBYS BRIEFLY...IF AT ALL. BEST CHC WOULD BE AT
LWB. NEAR FRONTAL BOUNDARY IN PIEDMONT...MVFR CIGS LIKELY TO LAST
THROUGHOUT THE NIGHT BUT NOT EXPECTING IFR FOG THERE EITHER
ANYMORE. A SPRINKLE AT DAN NOT OUT OF THE QUESTION THOUGH THROUGH
EARLY MORNING HOURS.
GENERALLY VFR FOR MOST OF THE DAY THURSDAY AHEAD OF THE NEXT WAVE
THAT WILL BE MOVING UP THE STALLED FRONT FROM THE SOUTHWEST.
MOISTURE WILL QUICKLY DEEPEN AGAIN BY LATE IN THE DAY FROM
SOUTHWEST TO NORTHEAST...WITH MORE WIDEPSREAD RAIN EXPECTED IN THE
WEST BY EVENING AND OVERNIGHT COMPARED TO THIS PAST SYSTEM...MORE
SHOWERY EAST OF THE BLUE RIDGE. EXPECTING BETTER CHANCE OF IFR
CONDITIONS BY DARK MOST TAF SITES. SMALL THREAT FOR THUNDER IN FAR
SW...MAYBE GETTING TO BLF OR BCB...BUT NOT LIKELY. WINDS AT RIDGE
TOP STRONG AGAIN FROM SW JUST AHEAD OF FRONT...WHICH WILL BE SWUNG
BACK THROUGH FROM WEST BEHIND DEVELOPING SFC LOW PRESSURE BY LATE
EVENING...AND THESE COULD BE MIXED DWON TO SFC IN HEAVIER
SHOWERS...BEST CHANCES AT BLF...BCB...AND MAYBE ROA. GUSTS TO 40
MPH POSSIBLE BUT NOT CONFIDENT ENOUGH TO PUT IN TAFS YET.
THIS SYSTEM CLEARS OUT BY FRIDAY...WITH VFR CONDITIONS EXPECTED
IN THE EAST...AND POSSIBLY MVFR UPSLOPE CLOUDS IN THE MOUNTAINS
WITH A FEW SHWRS POSSIBLE AT BLF ESPECIALLY. EVERYONE SHOULD BECOME
VFR BY SATURDAY AS HIGH PRESSURE BUILDS IN. A STORM MAY BRING
ANOTHER ROUND OF RAIN SUNDAY...ALTHOUGH MODELS HAVE BEEN TRENDING
FURTHER SOUTH WITH THIS STORM. THUS BEST CHANCE OF RAIN AND
REDUCED CEILINGS APPEARS TO BE CLOSER TO THE NC/VA BORDER IF
ANYWHERE.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...RCS/SK
NEAR TERM...RCS/SK
SHORT TERM...WERT
LONG TERM...MC
AVIATION...MC/RCS/SK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
305 AM CST THU DEC 22 2011
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
305 AM CST THU DEC 22 2011
MAIN CONCERNS WILL BE LINGERING SNOW ACROSS SOUTHERN WI INTO
NORTHEAST IA EARLY THIS MORNING...THEN SLIGHT SNOW CHANCES ACROSS
NORTHERN WISCONSIN ON FRIDAY.
RADAR AND SURFACE OBSERVATIONS SHOWING A BAND OF LIGHT SNOW
EXTENDING FROM EAST CENTRAL WISCONSIN...THROUGH SOUTHWEST WI AND
CENTRAL IA. AT THE NWS OFFICE HERE AROUND A HALF INCH HAS FALLEN SO
FAR. SHORTWAVE TROUGH PRODUCING LIFT FOR THIS SNOW WAS INDICATED ON
WATER VAPOR IMAGERY ACROSS SD/NEB. AIDING IN THE BANDING OF THIS
SNOW WAS CONFLUENT 850-700MB FLOW/WEAK FRONTOGENESIS INDICATED BY
THE RUC MODEL FROM NORTHEAST IA INTO SOUTHERN WI. LOWEST VISIBILITY
UNDER THE HIGHEST REFLECTIVITY BAND ON RADAR AROUND 1SM AT BOSCOBEL
AND MINERAL POINT WI. OTHERWISE...UNDER MOSTLY CLOUDY SKIES ACROSS
THE FORECAST AREA...TEMPERATURES AT 3 AM RANGED FROM THE MID 20S
ACROSS NORTH CENTRAL WI TO THE LOWER 30S SOUTH OF I-90.
22.00Z NCEP MODEL SUITE/29.03Z SREF IN GOOD AGREEMENT THROUGH THE
SHORT TERM.
FOR TODAY...MAIN CONFLUENT 850-700MB FLOW/FRONTOGENESIS SHIFTS
SOUTHEAST OF THE AREA BY 9 AM...BRINGING AN END TO SNOW CHANCES FOR
THE AREA. OTHERWISE...IR IMAGERY SHOWS A DECENT FIELD OF
STRATOCUMULUS ACROSS MN INTO WI...AND THIS WILL LIKELY HOLD THROUGH
MUCH OF THE MORNING...THEN START TO SCOUR OUT THROUGH THE AFTERNOON
HOURS AS A RIDGE OF HIGH PRESSURE/INCREASING SUBSIDENCE BUILDS IN
FROM THE PLAINS.
NORTHWEST FLOW ALOFT WILL BRING A FAIRLY VIGOROUS MID-LEVEL
SHORTWAVE TROUGH AND SURFACE LOW ACROSS SOUTHERN ONTARIO/LAKE
SUPERIOR REGION ON FRIDAY. NAM/GFS SHOW BEST FORCING AND CHANCES FOR
SNOW WILL BE CONFINED CLOSE TO THE TROUGH/LOW. HOWEVER...THE 29.00Z
ECMWF/GEM SHOW LIGHT QPF ALL THE WAY DOWN TO I-94. WENT WITH A
COMPROMISE AND KEPT A SMALL/SLIGHT CHANCE POP IN FOR TAYLOR COUNTY.
THE FORECAST AREA WILL THEN BE IN THE WARM SECTOR OF A LOW PRESSURE
SYSTEM PASSING THROUGH CANADA ON SATURDAY. SOUTHWEST SURFACE FLOW
AND AMPLE SUNSHINE SHOULD WARM HIGHS WELL INTO THE 30S WITH PERHAPS
A FEW READINGS AROUND THE 40 DEGREE MARK ACROSS FAR SOUTHWEST
WI/NORTHEAST IA.
.LONG TERM...CHRISTMAS DAY THROUGH WEDNESDAY
305 AM CST THU DEC 22 2011
22.00Z GFS/ECMWF IN DECENT AGREEMENT THROUGH THE LONG TERM.
A COLD FRONT WILL DROP SOUTH ACROSS THE AREA CHRISTMAS DAY...BUT
APPEARS THE BULK OF THE COLD AIR ADVECTION WILL BE ALONG/NORTHEAST
OF I-94. AS A RESULT...COULD SEE HIGHS AROUND THE 40 DEGREE MARK
AGAIN SOUTHWEST OF I-94...ESPECIALLY FROM FAR SOUTHWEST WI INTO
NORTHEAST IA. OTHERWISE...WILL PROBABLY SEE SOME BLUSTERY CONDITIONS
WITH GOOD MIXING/FAIRLY TIGHT PRESSURE GRADIENT.
FAIRLY ACTIVE ZONAL FLOW REMAINS IN PLACE WITH STORM SYSTEMS STAYING
MAINLY NORTH OF THE U.S./CANADIAN BORDER. THIS KEEPS PRECIPITATION
CHANCES NORTH OF THE AREA AND WILL CONTINUE TO PRODUCE ABOVE NORMAL
TEMPERATURES.
&&
.AVIATION...THROUGH 06Z FRIDAY
1134 PM CST WED DEC 21 2011
BAND OF VERY LIGHT SNOW OVER BOTH KLSE AND KRST TAF SITES AS OF
05Z THURSDAY IS SLOWLY DRIFTING TO THE SOUTH...SUCH THAT THE SNOW
SHOULD BE OUT OF KRST BY 07Z AND KLSE BY 09Z. MVFR VISIBILITIES
ARE THE LOWEST FORECAST AT THIS TIME...THOUGH CANNOT RULE OUT A
VERY BRIEF PERIOD OF IFR AT KLSE. VFR VISIBILITIES SHOULD THEN BE
THE RULE THROUGH THE REST OF THE PERIOD AS DRIER SURFACE AIR MOVES
IN ON A 5 TO 15 KT NORTHWEST WIND. CEILING HEIGHTS ARE A LITTLE
MORE PROBLEMATIC. VFR CEILINGS OVER KRST SHOULD LOWER TO MVFR
AROUND 09Z AS MVFR STRATUS FROM MINNEAPOLIS AND RED WING MOVES
IN. KLSE MAY BOUNCE BETWEEN MVFR AND VFR...MOSTLY DUE TO THE
SNOW...UNTIL THE STRATUS MOVES IN THERE AROUND 09Z. ANTICIPATING
THE STRATUS TO SCATTER OUT AROUND 18Z...DUE TO DAYTIME HEATING AND
DRIER AIR MOVING IN. THIS DRIER AIR CAN CURRENTLY BE SEEN OVER
NORTHWEST MINNESOTA WHERE CLOUDS HAVE BEEN SCOURING OUT. LOOK FOR
THE VFR CEILINGS TO THEN PERSIST THROUGH 06Z FRIDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
305 AM CST THU DEC 22 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...RIECK
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1055 PM CST WED DEC 21 2011
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.UPDATED...LOWERED THE PROBABILITY OF SNOW IN THE FORECAST OVER
MOST OF THE AREA NORTH OF A WAUSAU TO GREEN BAY LINE. INITIAL SNOW
OVER NORTHCENTRAL WISCONSIN DURING THE LATE AFTERNOON AND EARLY
EVENING HAD THE BENEFIT OF LOW LEVEL WARM ADVECTION AND
CONVERGENCE IN ADDITION TO THE UPPER JET DYNAMICS. THE LOW LEVEL
FORCING HAS SINCE DIMINISHED AND SO HAS THE SNOW.
AS OF 830 PM THERE WERE ECHOES OVER THE CENTRAL PART OF THE
FORECAST AREA BUT LITTLE OR NOTHING REACHING THE GROUND DUE TO
VERY DRY AIR INITIALLY ACROSS THE AREA. THE PRECIPITABLE WATER OF
THE 00Z GREEN BAY SOUNDING WAS ONLY .22 INCHES. THE MINNEAPOLIS
SOUNDING STARTED OFF SIMILARLY AT 12Z AND MOISTENED UP TO ABOUT
.40 INCHES BUT ONLY MANAGED A TRACE OF SNOW. ALL IS NOT LOST FOR
THOSE WISHING FOR SNOW AS SOME BETTER RADAR REFLECTIVITIES OVER
IOWA ARE MOVING TO THE NORTHEAST. THESE CORRELATE WELL WITH THE
500MB DIVERGENCE OF THE 00Z RUC WHICH WOULD TAKE THIS SNOW
GENERALLY TO THE AREA SOUTH OF A KEWAUNEE TO WAUPACA.
THINK THAT THE ATMOSPHERE WILL MANAGE TO PRODUCE SOME LIGHT SNOW
OR AT LEAST FLURRIES IN THE FOX VALLEY...LAKESHORE AND WAUSHARA
AND WAUPACA COUNTIES LATE TONIGHT OR EARLY THURSDAY BUT PROBABLY
JUST A DUSTING TO A HALF INCH DUE TO THE DRY AIR CURRENTLY IN
PLACE.
RDM
&&
.PREV DISCUSSION...ISSUED AT 624 PM CST WED DEC 21 2011...
SHORT TERM...TONIGHT AND THURSDAY...SNOW TRENDS AND ACCUMULATIONS
ARE THE MAIN FCST CONCERNS.
A COLD FRONT WAS MOVG THROUGH THE NW HALF OF THE CWA THIS AFTERNOON.
MID-LEVEL FRONTOGENETIC FORCING SITUATED JUST NW OF THE FRONT WAS
GENERATING A BAND OF LIGHT SNOW FROM CENTRAL MN INTO NC WI...WITH
OCNL VSBYS OF 1-2SM. MODELS ARE IN GENERAL AGREEMENT THAT THIS
BAND OF SNOW WILL GRADUALLY WEAKEN DURING THE LATE AFT/EARLY EVG...
WITH ANOTHER MORE SIGNIFICANT BAND SETTING UP OVER PARTS OF C/EC WI
LATE TONIGHT. HAVE KEPT CHC POPS ACROSS THE NW TWO-THIRDS OF THE CWA
THIS EVG...THEN LIKELY POPS MAINLY SOUTH OF A MFI-SUE LINE AFTER
MIDNIGHT. THE SNOW WILL CONTINUE TO SAG SOUTH THROUGH OUR SOUTHERN
COUNTIES ON THURSDAY MORNING...AND SHOULD BE OUT OF THE FA BY
MIDDAY. DON`T THINK THAT SNOWFALL TOTALS WILL GET OUT OF HAND...
AS THE INITIAL AIR MASS IS QUITE DRY...AND THERE IS LITTLE
EVIDENCE OF ANY INSTABILITY THAT MIGHT ENHANCE/FOCUS THE FGEN
FORCING. REGARDLESS...IT APPEARS THAT PARTS OF C/EC WI WILL SEE
AROUND AN INCH OF SNOW...WHICH COULD MAKE FOR A SLIPPERY COMMUTE
ON THURSDAY MORNING.
COLDER NNW FLOW WILL BRING A CHC OF LAKE-EFFECT SNOW SHOWERS TO
NC WI LATE TONIGHT INTO THURSDAY. WITH LIGHT WINDS (10-15 KTS)
IN THE 925-850 MB LAYER...WOULD NOT EXPECT THE SNOW SHOWERS TO
MOVE VERY FAR INLAND...SO WILL MAINLY CONFINE POPS TO VILAS
COUNTY FOR NOW.
LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY.
STILL NO SIGNIFICANT CHANGES IN SPLIT FLOW PATTERN THRU FIRST
PART OF NEXT WEEK. SOME HINT OF MORE ZONAL/WNW FLOW PATTERN LATER
NEXT WEEK. OVERALL...WEATHER QUIET FOR THIS TIME OF YEAR.
SERIES OF NW PACIFIC SYSTEMS MOVE ACROSS THE REGION DURING THIS
PERIOD IN NORTHERN STREAM...BUT LITTLE IN THE WAY OF WEATHER
OUTSIDE OF CLOUDS AND FLURRIES...AS THESE SYSTEMS ARE MOISTURE-
STARVED DUE TO SPLIT FLOW. BOTH 21/12Z GFS AND ECMWF INDICATE
SYSTEM ON FRIDAY HAS ENOUGH UPPER LEVEL DYNAMICS TO OVERCOME
INITIALLY DRY COLUMN AND PRODUCE A PERIOD OF SNOW SHOWERS ACROSS
THE NORTH THIRD.
TEMPERATURES WILL BE ABOVE NORMAL FOR MUCH OF PERIOD AS ARCTIC
AIR REMAINS GENERALLY BOTTLED UP N OF 50 N.
&&
.AVIATION...MVFR CIGS ACROSS MOST OF THE REGION OVERNIGHT. A BAND
OF LIGHT SNOW WILL MOVE ACROSS CENTRAL AND EAST CENTRAL WISCONSIN
WITH MVFR VSBYS AND LOCAL BRIEF IFR POSSIBLE. VFR EXPECTED OVER
MOST OF THE AREA BY EARLY AFTERNOON THURSDAY.
RDM
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
647 AM EST THU DEC 22 2011
.SYNOPSIS...
A SLOW MOVING FRONTAL SYSTEM WILL REMAIN NEAR THE FORECAST AREA
THROUGH THE CHRISTMAS WEEKEND. A SERIES OF LOW PRESSURE SYSTEMS WILL
MOVE NORTHEASTWARD ALONG THE FRONT.
&&
.NEAR TERM /THROUGH TODAY/...
SCATTERED SHOWERS DEVELOPING ACROSS SOUTH GEORGIA THIS MORNING
ASSOCIATED WITH WARM ADVECTION. LATEST RUC SUGGESTS THESE SHOWERS
WILL CONTINUE TO TRACK NORTHEAST INTO THE CSRA LATER THIS MORNING
AND ACROSS THE MIDLANDS. BASED ON 850MB TEMPERATURES EXPECT ANOTHER
WARM DAY WITH TEMPERATURES IN THE LOWER 70S. MAY BE HIGHER IF
BREAKS IN THE CLOUDS THIS AFTERNOON.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
WEAK CONVERGENCE AND MOISTURE ASSOCIATED WITH THE SLOW MOVING
FRONT WILL SUPPORT A CONTINUED SHOWER CHANCE...ALTHOUGH WITH LACK
OF UPPER LEVEL SUPPORT...AND LOW SREF POPS...DECREASED POPS FROM
PREVIOUS FORECAST INTO FRIDAY MORNING. THE NAM AND GFS SHOW SOME
DRYING DEVELOPING FRIDAY AS THE FRONT PUSHES A LITTLE FARTHER
SOUTHEASTWARD.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
CONFIDENCE REMAINES LOW HOWEVER WITH THE FORECAST THROUGH THE
EXTENDED PERIOD. LATEST GFS/ECMWF ADVECTING MOISTURE FROM THE
GULF NORTHEAST INTO GEORGIA AND SOUTH CAROLINA FASTER THAN NAM
SATURDAY NIGHT AS NAM CLOSES OFF UPPER LOW IN THE SOUTHERN PLAINS.
POPS THOUGH SHOULD REMAIN LOW SATURDAY NIGHT. UNCERTAINTY
CHRISTMAS DAY WITH MEAN GFS ENSEMBLE POPS LOWER THAN OPERATIONAL
GFS. LITTLE CHANGE MADE TO FORECAST FOR CHRISTMAS...CHANCE POPS
AND TEMPERATURES ABOVE NORMAL SEEMS REASONABLE. DRYING MONDAY WITH
RIDGING BECOMING DOMINATE TUESDAY. TEMPERATURES NEAR NORMAL.
&&
.AVIATION /12Z THURSDAY THROUGH TUESDAY/...
REGIONAL RADAR COMPOSITE SHOWS LIGHT RAIN SHOWERS MOVING NORTHEAST
ALONG THE I-95 CORRIDOR AND FROM MACON GA TOWARD THE CSRA.
OBS/SATELLITE INDICATE IFR/MVFR CONDITIONS AT ALL TAF SITES THIS
MORNING.
MODEL SOUNDINGS CONTINUE TO SHOW ABUNDANT LOW LEVEL MOISTURE ACROSS
THE REGION THIS MORNING AND THROUGH THE TAF PERIOD. OBS UPSTREAM
INDICATE THAT CONDITIONS COULD CONTINUE TO DETERIORATE AT ALL TAF
SITES THROUGH MID/LATE MORNING WITH CONTINUED IFR/MVFR CONDITIONS.
WILL ALSO MENTION VCSH FOR ISOLATED LIGHT SHOWERS/SPRINKLES AT BOTH
OGB/AGS THROUGH THE MORNING/AFTERNOON HOURS. CONDITIONS MAY IMPROVE
THIS AFTERNOON TO VFR AT ALL TAF SITES...AND HAVE INDICATED THIS IN
TAFS AFTER 21Z. HOWEVER...THERE IS A CHANCE THAT CONDITIONS WILL
ONLY IMPROVE TO MVFR. TONIGHT...EXPECT CONDITIONS TO ONCE AGAIN
DETERIORATE AS ADDITIONAL MOISTURE STREAMS NORTHEAST AHEAD/ALONG
FRONTAL BOUNDARY AND MVFR CONDITIONS RETURN. POTENTIAL EVEN EXIST
FOR A PERIOD OF IFR FRIDAY MORNING...BUT HAVE DECIDED NOT TO GO THAT
LOW OR MENTION ANY SHOWERS AT THIS TIME. WINDS WILL BE LIGHT FROM
THE SOUTH THIS MORNING...THEN INCREASING TO NEAR 10 KNOTS FROM THE
SOUTH THIS AFTERNOON/TONIGHT.
EXTENDED AVIATION OUTLOOK...PERIODS OF CIG/VSBY RESTRICTIONS
EXPECTED THROUGH SATURDAY AS A SERIES OF WEATHER SYSTEMS CROSS THE
REGION.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
539 AM CST THU DEC 22 2011
.AVIATION...
FOR THE 12Z TAF ISSUANCE...
LIGHT SNOW WILL CONTINUE TO DEVELOP SOUTHWARD THIS MORNING AND
AFFECT GCK, DDC, AND HYS TERMINALS FOR SEVERAL HOURS TODAY. AT
THIS TIME...BELIEVE THAT THE LIGHT SNOW EVENT WILL LAST NO MORE
THAN ABOUT 4 OR 5 HOURS AS THIS WILL NOT BE A VERY SIGNIFICANT
PRECIPITATION EVENT. NEVERTHELESS...STRONG NORTHEAST WINDS
COMBINED WITH EVEN LIGHT SNOW WILL LOWER VISIBILITY DOWN TO THE 1
TO 2 MILE RANGE FOR SOME TIME DURING THE EVENT. IFR CONDITIONS
SHOULD PERSIST THROUGH THE DAY UNTIL ABOUT 21Z AT GCK AND DDC AND
ABOUT 19Z AT HYS. -UMSCHEID
&&
.PREV DISCUSSION... /ISSUED 225 AM CST THU DEC 22 2011/
SYNOPSIS...
22.00Z 300 HPA JET ANALYSIS SHOWS THAT KANSAS LIES BETWEEN A STRONG
SOUTHERN JET EXTENDING FROM MEXICO TO THE LOWER MISSISSIPPI RIVER VALLEY
AND A NORTHERN JET WAS SLIDING EAST ACROSS THE NORTHERN PLAINS. A 75-85
KT JET WAS MOVING PUSHING SOUTHWARD UPSTREAM OF A 500 HPA LOW PRESSURE
CENTER LOCATED ACROSS EASTERN UTAH. MID ATMOSPHERE ANALYSIS INDICATES
COLD AIR OF -30 TO -37 DEG C AIR FROM WYOMING NORTHWARD TO/ACROSS THE
CANADIAN PRAIRIES. AT 700 AND 850 HPA...COLDER AIR WAS ADVECTING ACROSS
THE NORTHERN AND CENTRAL PLAINS. AT THE SURFACE, A COLD FRONT WAS PUSHING
ACROSS THE STATE OF KANSAS EARLY THIS MORNING. -SUGDEN
DISCUSSION...
DAYS 1-2...
TODAY:
THE AFOREMENTIONED MID ATMOSPHERIC LOW WILL SINK SOUTHWARD FROM UTAH
TO THE 4 CORNERS REGION. THE 80-90 KT JET WRAPPING AROUND THIS LOW WILL
PUT WESTERN KANSAS JUST NORTH OF THE LEFT EXIT REGION WITH DYNAMIC LIFT
AND 700 OMEGA DEVELOPING ACROSS THE REGION. IN ADDITION, UPSLOPE 700/850
HPA FLOW WILL PROVIDE ENOUGH LOW TO MID LEVEL LIFT TO PROVIDE THE REGION
WITH LIGHT SNOW SHOWERS TODAY. THE LATEST HRRR (WHICH ONLY GOES OUT
TIL ABOUT 20Z) WAS USED AS A STARTING FOUNDATION FOR SNOW ACCUMULATION.
MUCH OF THE REGION WILL SEE ABOUT 0.5 TO 1.0 INCHES WITH SLIGHTLY MORE
POSSIBLE ACROSS MY NORTHWEST COUNTIES (FLIRTING TO AROUND 2.0 INCHES).
HAVE ADDED BLOWING SNOW BASED OFF UPSTREAM OBSERVATIONS SHOWING A REDUCTION
IN VISIBILITIES ALREADY. OTHERWISE, TODAY WILL BE CLOUDY WITH NORTH
TO NORTHEASTERLY WINDS RUNNING AROUND 20 KT IN THE WAKE OF A COLD FRONT.
WILL HIGHLIGHT THE LIGHT SNOW ACCUMULATIONS/BLOWING SNOW IN THE HWO
BUT THIS WILL BE BELOW ADVISORY CRITERIA SO AM NOT PLANNING TO ISSUE
A WSW RIGHT NOW. MAXIMUM TEMPERATURES WILL BE IN THE UPPER 20S TO LOWER
30S DEG F.
TONIGHT:
PRECIPITATION WILL END THIS EVENING FROM THE NORTHEAST TO THE SOUTHWEST
AS THE MID LEVEL LOW SINKS FURTHER SOUTH. FORECAST SOUNDINGS SHOW QUITE
A BIT OF DRYING LATE TONIGHT INTO TOMORROW MORNING SO I HAVE RAMPED
CLOUD COVER DOWN. WITH CLEARING SKIES AND A SURFACE HIGH PRESSURE CENTER
SLIDING ACROSS KANSAS, A GOOD NIGHT FOR RADIATIONAL COOLING IS EXPECTED.
MINIMUM TEMPERATURES IN THE SINGLE DIGITS DEG F IS EXPECTED ACROSS FAR
WESTERN KANSAS. SLIGHTLY WARMER TEMPERATURES WITH TEENS DEG F ARE EXPECTED
ACROSS SOUTH CENTRAL KANSAS.
FRIDAY/FRIDAY NIGHT:
I HAVE INCREASED TEMPERATURES FRIDAY AS A LEE TROUGH DEVELOPS ACROSS
THE LEE OF THE ROCKIES AND MOVES EAST IN ASSOCIATION WITH THE PASSAGE
OF A WEAK SHORTWAVE TROF TRAVERSING ACROSS THE NORTHERN PLAINS. MAXIMUM
TEMPERATURES SHOULD WARM TO NEAR TO SLIGHTLY ABOVE FREEZING WITH A BIT
OF DOWNSLOPE SOUTHWESTERLY TO WESTERLY SURFACE WINDS. A DRY ATMOSPHERE
WILL LEAD TO FULL INSOLATION ON FRIDAY AS WELL. A BIT OF EROSION OF
THE SNOW FIELD IS POSSIBLE FRIDAY FOR AREAS THAT GET ABOVE FREEZING.
OVERNIGHT LOWS INTO SATURDAY WILL BE SLIGHTLY WARMER WITH THE CONTINUATION
OF A DOWNSLOPE WESTERLY WIND. NO PRECIPITATION IS EXPECTED FRIDAY. -SUGDEN
DAYS 3-7...
THE PERIOD SATURDAY THROUGH WEDNESDAY WILL BE VERY QUIET SENSIBLE WEATHER
WISE WITH NO PRECIPITATION EXPECTED DURING THIS ENTIRE PERIOD. THE PLANETARY
SCALE PATTERN ACROSS THE NORTH PACIFIC INTO NORTH AMERICA WILL BE CHARACTERIZED
BY A LOW WAVE NUMBER/LOW AMPLITUDE WHICH WILL RESULT IN A WARMER-THAN-
AVERAGE PERIOD OF WEATHER ACROSS THE WESTERN PLAINS...IF IT WERE NOT
FOR A FAIRLY HEALTHY SNOW PACK IN PLACE.
THE 19-20 DECEMBER BLIZZARD CAUSED A LARGE SNOWPACK ACROSS SOUTHEASTERN
COLORADO AND WEST-CENTRAL/SOUTHWEST KANSAS WHICH WILL TAKE SEVERAL DAYS
TO DWINDLE DOWN. AS A RESULT...HIGH TEMPERATURE FORECASTING WILL BE
DIFFICULT...AND WILL BE DEPENDENT UPON THE DAILY REDUCTION OF THE SNOWPACK.
AN UPPER RIDGE WILL BUILD OVER THE ROCKIES SATURDAY/SATURDAY NIGHT...WHICH
WILL THEN ERODE AS ZONAL JET FLOW MOVES INTO THE NORTHERN ROCKIES SPAWNING
A DEEP LEE TROUGH FROM ALBERTA SOUTH TO EASTERN COLORADO. THIS LOOKS
LIKE A CLASSIC DOWNSLOPE WARMING SETUP AND IT WOULD APPEAR ON PAPER
THAT THIS DAY WILL BE QUITE WARM AND WILL REALLY KNOCK OUT A GOOD CHUNK
OF WHATEVER REMNANT SNOWPACK THERE IS ACROSS WESTERN DDC FORECAST AREA.
WITH SOME COLLABORATION HAVE INCREASED THE HIGHS A FEW DEGREES OVER
THE ALLBLEND GUIDANCE FOR MONDAY. THIS IS THE ONLY CHANGE MADE AGAINST
THE ALLBLEND GUIDANCE FOR THE MEDIUM RANGE.
IN THE FAR EXTENDED TIME FRAME...AN EXTENDED NORTH PACIFIC JET WILL
MIGRATE EASTWARD DURING THE 27-30 DECEMBER TIME FRAME WITH A HINT AT
RIDGE BUILDING SOMEWHERE BETWEEN 140W AND 120W...WHICH COULD FAVOR DOWNSTREAM
TROUGH DEVELOPMENT OVER THE WESTERN OR CENTRAL CONUS BY THE 30-31 DECEMBER
TIME FRAME. THIS WOULD BE THE EARLIEST TIME FRAME THAT PRECIPITATION
CHANCES COULD ENTER THE PICTURE...BUT THIS IS IN THE DAY 8-10 TIME FRAME
AND IT REMAINS TO BE SEEN HOW THE SYNOPTIC SCALE EVOLVES AS THE EXTENDED
JET APPROACHES THE NORTHEAST PACIFIC. -UMSCHEID
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 30 14 33 14 / 50 10 0 0
GCK 32 8 33 12 / 60 20 0 0
EHA 29 10 27 16 / 70 20 0 0
LBL 31 12 31 15 / 60 20 0 0
HYS 32 13 34 14 / 60 10 0 0
P28 34 19 36 21 / 50 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN99/99/25
AREA FORECAST DISCUSSION
NWS GAYLORD MI
620 AM EST THU DEC 22 2011
.SYNOPSIS.../ISSUED AT 355 AM/
A COLD FRONT WILL SLOWLY MOVE SOUTH ACROSS NORTHERN MICHIGAN TODAY.
THIS WILL BRING LIGHT SNOW...MAINLY THROUGH EARLY AFTERNOON...AND
MAINLY IN NORTHERN LOWER MICHIGAN. SOME LAKE EFFECT WILL DEVELOP
BEHIND THE FRONT THIS AFTERNOON...AND CONTINUE INTO TONIGHT...BEFORE
TAPERING. A FAST MOVING UPPER LEVEL DISTURBANCE WILL BRING ANOTHER
ROUND OF LIGHT SNOW TO MOST OF NORTHERN MICHIGAN FRIDAY EVENING.
AFTER THAT...OUR NEXT FOR SNOW WILL ARRIVE ON CHRISTMAS DAY.
THROUGHOUT ALL OF THIS...TEMPERATURES WILL REMAIN NEAR OR ABOVE
NORMAL.
JZ
&&
.SHORT TERM.../ISSUED AT 556 AM/...TODAY
UPDATE: HAVE THROWN IN A RAIN/SNOW MIX ALONG THE IMMEDIATE
LAKESHORES THIS MORNING PER OBS...WITH RUC FCST SOUNDINGS SUGGESTIVE
OF SFC-BASED MELTING LAYERS UP TO AROUND 1.5KFT. COMBINED WITH SFC
TEMPS INTO THE MIDDLE 30S...SHOULD CONTINUE TO SEE RAIN MIX IN WITH
THE SNOW RIGHT NEAR THE COAST GIVEN A WESTERLY WIND FLOW OFF LAKE
MICHIGAN. HAVE ALSO LOWERED FCST SNOW AMOUNTS A BIT AFTER 12Z...AND
SHIFTED AXIS OF "HEAVIEST" SNOW (STILL WELL UNDER AN INCH) SOUTHWARD
A BIT BETWEEN M-72 AND M-55 PER RADAR EXTRAPOLATION OF BEST FGEN
BANDING.
LAWRENCE
PREVIOUS DISCUSSION BELOW (ISSUED AT 355 AM):
PRIMARY FCST CONCERN THROUGH THE DAY COMES MAINLY THIS MORNING...IN
THE FORM OF TIMING/PLACEMENT OF FGEN-DRIVEN BAND OF MAINLY LIGHT
SNOW SLIDING THROUGH MAINLY NORTHERN LOWER MICHIGAN. EARLY MORNING
ANALYSIS SHOWS BROAD UPPER TROUGHING ACROSS THE UPPER MIDWEST...WITH
A SHARPER SOUTHERN STREAM WAVE LIFTING THROUGH THE SOUTHERN PLAINS.
TIGHTENING CONFLUENCE AXIS BETWEEN THESE TWO SYSTEM IS FORCING AN
INCREASED MID LEVEL FRONTOGENETIC RESPONSE IN A NARROW AXIS FROM
SOUTHERN NEBRASKA INTO NORTHERN MICHIGAN...WITH UPSTREAM OBS AND
RADAR IMAGERY SHOWING A GRADUALLY EXPANDING (ALBEIT RATHER NARROW)
CORRIDOR OF LIGHT SNOW ONGOING. CLOSER TO HOME...QUITE THE DRY WEDGE
TO OVERCOME PER 00Z APX/GRB RAOBS...THOUGH FGEN FORCING AND
ASSOCIATED GRADUAL MOISTENING FROM TOP DOWN IS WINNING THE BATTLE
WITH TIME.
EXPECT TO SEE THIS BAND OF LIGHT SNOW GRADUALLY WORK ITS WAY
SOUTHWARD THROUGH NORTHERN LOWER INTO MIDDAY...THOUGH WEAKENING
RATHER RAPIDLY WITH TIME BY 18Z AS CONFLUENCE/FGEN WANE
CONSIDERABLY. PER RADAR AND SHORT TERM GUIDANCE (RUC/HRRR/NAM)
TRENDS...STILL APPEAR THE "BEST" SNOWFALL WILL FALL BETWEEN ROUGHLY
M-32 AND M-72...WHERE PERHAPS AN INCH OR TWO WILL BE POSSIBLE AS
BEST MID LEVEL OMEGA BRIEFLY BISECTS A RATHER DEEP DGZ (I.E.
SLIGHTLY BETTER RATIOS). PROBABLY NOT LOOKING AT MUCH LEFT OF THIS
SNOW BAND AFTER 18Z...THOUGH THE CHANCES ARE NOT TOTALLY ZERO ACROSS
THE SOUTHERN COUNTIES...WHERE WILL MAINTAIN A SMALL CHANCE FOR SOME
LIGHTER SNOW SHOWERS. OTHERWISE...FOCUS SHIFTS TO LAKE EFFECT
POTENTIAL AS COLDER AIR GRADUALLY SEEPS INTO THE AREA...WITH H85
TEMPS SETTLING IN AROUND -13C ON LAKE SUPERIOR TO -10C OVER LAKE
MICHIGAN. MOISTURE PROFILES NOTHING TERRIBLY IMPRESSIVE IN EITHER
LOCATION...THOUGH OVERLAKE INSTABILITY AND THUS LAKE-INDUCED
BOUNDARY LAYER DEEPER ON LAKE SUPERIOR. HOWEVER...VEERING LOW LEVEL
FLOW PROFILES MORE NORTHERLY SUPPORT BEST CHANCES ONLY ACROSS FAR
NORTHWEST CHIPPEWA COUNTY WHERE WILL CARRY A LIKELY POP (WITH ACCUMS
LESS THAN AN INCH). FARTHER SOUTH...SIMILAR FLOW REGIME WILL GIVEN
AT LEAST A SMALL CHANCE FOR SOME LIGHT SNOW SHOWERS VICINITY OF
GRAND TRAVERSE BAY...THOUGH LESS THAN STELLAR INSTABILITY AND CLOUD
TOP TEMPS ONLY AROUND -10C JUST DON`T DO MUCH TO BOLSTER ANY
CONFIDENCE ABOUT A CHANCE POP. HIGH TEMPS TO REMAIN A FEW DEGREES
ABOVE NORMAL...WITH READINGS SLOWLY FALLING THROUGH THE AFTERNOON
AND EARLY EVENING.
LAWRENCE
&&
.LONG TERM.../ISSUED AT 355 AM/...TONIGHT AND BEYOND
RATHER ACTIVE NORTHERN GREAT LAKES WEATHER REGIME EXPECTED THROUGH
CHRISTMAS DAY...AND PERHAPS BEYOND...THOUGH WITH NO MAJOR WEATHER
SYSTEMS AFFECTING THE AREA. STILL...DOES APPEAR AT LEAST A FEW
CHANCES FOR ACCUMULATING SNOW WILL EXIST HEADING INTO CHRISTMAS DAY.
FOR TONIGHT...COLDEST OF THE AIR ARRIVES...WITH H85 TEMPS DIPPING
TOWARD -15C...ALL WHILE ELONGATED LOW LEVEL RIDGING ATTEMPTS TO
BUILD THROUGH THE REGION. WHILE SETUP FOR LAKE EFFECT FROM A LAKE
INSTABILITY STANDPOINT LOOKS GREAT...LACK OF DEEPER MOISTURE...LOW
INVERSION HEIGHTS...AND RATHER LIGHT (AND THUS MESOSCALE-DOMINATED)
BOUNDARY LAYER FLOW REGIME WILL NOT WORK IN OUR FAVOR. BUBBLE HIGH
SETUP INTO ONTARIO SHOULD SUPPORT A DECENT DRAINAGE FLOW LATER
TONIGHT...ACTING TO FORCE BEST POTENTIAL FOR LAKE SNOWS WEST OF
CHIPPEWA COUNTY...THOUGH PERHAPS SETTING UP A LOCALIZED STRONGER
CONVERGENCE AXIS SOMEWHERE JUST WEST OF WHITEFISH POINT. SAID
DRAINAGE FLOW MAY ALSO ACT TO KICK SOME LAKE SNOW SHOWERS DEEPER
INTO PORTIONS OF NORTHEAST LOWER FOR A TIME. BEST CHANCES FOR SNOW
SHOWERS ACTUALLY APPEAR TO BE IN THE VICINITY OF GRAND TRAVERSE
BAY...WHERE MEAN LOW LEVEL NORTH/NORTHEAST (020 DEGREES) FLOW IN
COMBINATION WITH LONGER FETCH AND POSSIBLY SOME LAKE SUPERIOR
CONNECTION MAY BRING A COUPLE INCHES...MOST LIKELY INTO LEELANAU/
NORTHERN GRAND TRAVERSE COUNTIES. AS FOR LOWS...SHOULD BE A COLD
NIGHT FOR AREAS ALONG AND EAST OF I-75 IN EASTERN UPPER WITH
DRAINAGE FLOW SETUP...AND COULD SEE SOME SINGLE DIGIT READINGS
ACROSS INTERIOR NORTHERN LOWER AS WELL...SHOULD CLOUDS CLEAR UNDER
NORTH FLOW REGIME.
LAKE SNOW SHOWERS SHOULD WIND DOWN FRIDAY MORNING WITH SHARPLY
BACKING LOW LEVEL FLOW AND LOSS OF OVERLAKE INSTABILITY PER QUICK
PUSH OF WARM ADVECTION IN ADVANCE OF SHARPENING UPPER WAVE CROSSING
WESTERN LAKE SUPERIOR. SAID WAVE STILL FCST TO DROP BASICALLY
OVERHEAD FRIDAY EVENING...WITH QUICK SHOT OF DEEP LAYER QG-UPWARD
FORCING AND STRONG ISENTROPIC UPGLIDE ACTING TO ADVANCE AN AXIS OF
SNOW THROUGH ALL OF EASTERN UPPER AND LIKELY MUCH OF NORTHERN LOWER.
WILL PROBABLY SEE A LAKE MICHIGAN CONTRIBUTION AS WELL AS MARGINAL
INSTABILITY REMAINS OUT AHEAD OF THIS FEATURE...AND WILL CONTINUE TO
PAINT A GENERAL 2 TO 3 INCHES FROM THE STRAITS ON NORTH...TAPERING
TO LESS THAN A HALF INCH SOUTH OF AN ALPENA TO CADILLAC LINE WITH
LACK OF LAKE HELP AND WHERE PRONOUNCED DRY WEDGE BELOW 750MB WILL
TAKE SOME TIME TO OVERCOME.
TRANSIENT LOW LEVEL SHORTWAVE RIDGING ARRIVING IN THE WAKE OF THIS
SYSTEM EARLY SATURDAY ALONG WITH STARK WARM ADVECTION OUT AHEAD OF
NEXT APPROACHING UPPER WAVE SHOULD END ANY THREAT FOR LAKE SNOW
SHOWERS BEHIND THE INITIAL DEPARTING SHORTWAVE. THIS UPPER WAVE
SATURDAY AFTERNOON REALLY DOESN`T HAVE MUCH TO WORK WITH IN TERMS OF
MOISTURE...SO PERHAPS JUST A BRIEF INCREASE IN CLOUDS. NEXT...WE SET
OUR EYES ON THE NEXT UPPER WAVE AMPLIFYING INTO THE REGION LATER
SATURDAY NIGHT...WHICH SHOULD BEGIN TO SPREAD SOME LIGHT SNOW ACROSS
THE CENTRAL/EASTERN U.P. UP THROUGH CHRISTMAS MORNING.
LAWRENCE
REST OF THE FORECAST...REASONABLY VIGOROUS SHORTWAVE WILL DIG ACROSS
THE FORECAST AREA ON XMAS MORNING. DELTA T/S OF 12/13C ARE MARGINAL
FOR ANY LAKE ENHANCEMENT FOR THE BULK OF THE EVENT...COLD ADVECTION
DEVELOPS IN THE AFTERNOON JUST ABOUT AS DEEP MOISTURE PULLS OUT.
BUT...WITH SLIGHTLY BETTER MODEL AGREEMENT IN TIMING THIS FEATURE
IN...WILL GO AHEAD AND BUMP POPS UP JUST A BIT. SYSTEM HAS DECENT
DYNAMICS BUT IS (LIKE ALL WAVES IN THIS TIGHTLY-PACKED WAVE TRAIN)
SOMEWHAT MOISTURE-DEFICIENT. WOULD LEAN TOWARD ACCUMS OF 2 INCHES OR
LESS...THOUGH WITH SOME LOW-END BLOWING-DRIFTING WITH DEVELOPING
GUSTY NW WINDS. ANY SNOW MAY BE ON THE SLOPPY SIDE EARLY NEAR THE
LAKE MI COAST. ANY LINGERING LAKE EFFECT EARLY XMAS NIGHT WILL
QUICKLY GET CRUSHED BY DEEP SUBSIDENCE/DRYING/WARMING.
WX SYSTEMS WILL CONTINUE TO COME FAST AND NOT-AT-ALL-FURIOUS IN
RAPID WNW FLOW ALOFT. HOWEVER...MODEL TIMING DIFFERENCES ARE GROWING
WITH TIME...AND DON/T HAVE MUCH CONFIDENCE IN ANY ONE SOLUTION. BUT
EVEN THE FAST GFS WOULD ALLOW FOR A DRY/MILD MONDAY. GEM/ECMWF HOLD
OFF ON ANY REAL FORCING UNTIL TUESDAY...WHILE THE GFS BRINGS IN A
LEAD IMPULSE MONDAY NIGHT. PREFER THE GREATER RUN-TO-RUN CONSISTENCY
OF THE GEM/ECMWF CAMP...KEEPING MONDAY NIGHT LARGELY DRY...BUT
RETURNING A CHANCE OF SNOW IN SPOTS (MAINLY EASTERN UPPER MI) FOR
TUESDAY. LARGELY DRY FOR WEDNESDAY...AS WE FIND OURSELVES BRIEFLY
BETWEEN SYSTEMS AGAIN.
TEMPS ABOVE CLIMO THROUGHOUT...ESPECIALLY AT NIGHT AFTER SUNDAY
NIGHT. XMAS DAY WILL LIKELY FEATURE A NON-DIURNAL CURVE...WITH AN
EARLY HIGH AND FALLING (BUT NOT CRATERING) TEMPS IN THE AFTERNOON.
JZ
&&
.MARINE.../ISSUED AT 355 AM/
QUITE CHANGEABLE WEATHER CONDITIONS ARE EXPECTED OVER THE NEXT
SEVERAL DAYS...AS NUMEROUS WAVES OF LOW PRESSURE TRACK THROUGH THE
NORTHERN GREAT LAKES. WINDS WILL BY FAR BE THE LIGHTEST TODAY
THROUGH THE FIRST HALF OF FRIDAY...AS HIGH PRESSURE SLOWLY WORKS ITS
WAY THROUGH THE REGION...PROVIDING A MAINLY NORTHERLY FLOW REGIME.
WINDS WILL BACK QUICKLY TO THE SOUTHWEST AND INCREASE FRIDAY
AFTERNOON AND EVENING AS A CLIPPER SYSTEM CROSSES THE WATERS...WITH
SMALL CRAFT CONDITIONS BRIEFLY POSSIBLE. THEREAFTER...WINDS ARE
EXPECTED TO DIMINISH FOR A BRIEF TIME INTO EARLY SATURDAY...BEFORE
STRENGTHENING ONCE AGAIN SATURDAY NIGHT AS THE NEXT WAVE OF LOW
PRESSURE DROPS INTO THE GREAT LAKES. SMALL CRAFT ADVISORY OR EVEN
LOW GALE CONDITIONS ARE POSSIBLE DURING THIS TIME AS WELL.
LOOKING AHEAD...THIS GENERAL PATTERN WILL CONTINUE INTO EARLY NEXT
WEEK...WITH THE POTENTIAL FOR WIDESPREAD GALES LATER MONDAY INTO
TUESDAY AS A STRONG PUSH OF MUCH WARMER AIR ARRIVES.
LAWRENCE
&&
.AVIATION.../ISSUED AT 620 AM/...VALID FOR 12Z TAFS
A BAND OF LIGHT SNOW WILL CONTINUE ACROSS THE APN/TVC/MBL TERMINAL
SITES THROUGH MID MORNING...WITH BRIEF IFR CEILINGS/VISBYS
EXPECTED. A COLD FRONT CROSSING THE AREA WILL AID IN PUSHING THE
SNOW OUT OF THE PICTURE BY 16Z...WITH WIDESPREAD MVFR CEILINGS
EXPECTED IN THE WAKE OF THIS FRONT AS COLDER AIR ARRIVES. WINDS
MAY TURN A BIT GUSTY FROM THE NORTH BEHIND THE FRONT...
PARTICULARLY AT APN/TVC...BUT ANY GUSTS SHOULD REMAIN BELOW 18
KNOTS. A FEW LAKE EFFECT SNOW SHOWERS MAY ALSO WORK INTO THE TVC
TERMINAL THROUGH THE AFTERNOON...AND PERHAPS INTO APN AFTER SUNSET
TONIGHT.
LAWRENCE
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
556 AM EST THU DEC 22 2011
.SYNOPSIS.../ISSUED AT 355 AM/
A COLD FRONT WILL SLOWLY MOVE SOUTH ACROSS NORTHERN MICHIGAN TODAY.
THIS WILL BRING LIGHT SNOW...MAINLY THROUGH EARLY AFTERNOON...AND
MAINLY IN NORTHERN LOWER MICHIGAN. SOME LAKE EFFECT WILL DEVELOP
BEHIND THE FRONT THIS AFTERNOON...AND CONTINUE INTO TONIGHT...BEFORE
TAPERING. A FAST MOVING UPPER LEVEL DISTURBANCE WILL BRING ANOTHER
ROUND OF LIGHT SNOW TO MOST OF NORTHERN MICHIGAN FRIDAY EVENING.
AFTER THAT...OUR NEXT FOR SNOW WILL ARRIVE ON CHRISTMAS DAY.
THROUGHOUT ALL OF THIS...TEMPERATURES WILL REMAIN NEAR OR ABOVE
NORMAL.
JZ
&&
.SHORT TERM.../ISSUED AT 556 AM/...TODAY
UPDATE: HAVE THROWN IN A RAIN/SNOW MIX ALONG THE IMMEDIATE
LAKESHORES THIS MORNING PER OBS...WITH RUC FCST SOUNDINGS SUGGESTIVE
OF SFC-BASED MELTING LAYERS UP TO AROUND 1.5KFT. COMBINED WITH SFC
TEMPS INTO THE MIDDLE 30S...SHOULD CONTINUE TO SEE RAIN MIX IN WITH
THE SNOW RIGHT NEAR THE COAST GIVEN A WESTERLY WIND FLOW OFF LAKE
MICHIGAN. HAVE ALSO LOWERED FCST SNOW AMOUNTS A BIT AFTER 12Z...AND
SHIFTED AXIS OF "HEAVIEST" SNOW (STILL WELL UNDER AN INCH) SOUTHWARD
A BIT BETWEEN M-72 AND M-55 PER RADAR EXTRAPOLATION OF BEST FGEN
BANDING.
LAWRENCE
PREVIOUS DISCUSSION BELOW (ISSUES AT 355 AM):
PRIMARY FCST CONCERN THROUGH THE DAY COMES MAINLY THIS MORNING...IN
THE FORM OF TIMING/PLACEMENT OF FGEN-DRIVEN BAND OF MAINLY LIGHT
SNOW SLIDING THROUGH MAINLY NORTHERN LOWER MICHIGAN. EARLY MORNING
ANALYSIS SHOWS BROAD UPPER TROUGHING ACROSS THE UPPER MIDWEST...WITH
A SHARPER SOUTHERN STREAM WAVE LIFTING THROUGH THE SOUTHERN PLAINS.
TIGHTENING CONFLUENCE AXIS BETWEEN THESE TWO SYSTEM IS FORCING AN
INCREASED MID LEVEL FRONTOGENETIC RESPONSE IN A NARROW AXIS FROM
SOUTHERN NEBRASKA INTO NORTHERN MICHIGAN...WITH UPSTREAM OBS AND
RADAR IMAGERY SHOWING A GRADUALLY EXPANDING (ALBEIT RATHER NARROW)
CORRIDOR OF LIGHT SNOW ONGOING. CLOSER TO HOME...QUITE THE DRY WEDGE
TO OVERCOME PER 00Z APX/GRB RAOBS...THOUGH FGEN FORCING AND
ASSOCIATED GRADUAL MOISTENING FROM TOP DOWN IS WINNING THE BATTLE
WITH TIME.
EXPECT TO SEE THIS BAND OF LIGHT SNOW GRADUALLY WORK ITS WAY
SOUTHWARD THROUGH NORTHERN LOWER INTO MIDDAY...THOUGH WEAKENING
RATHER RAPIDLY WITH TIME BY 18Z AS CONFLUENCE/FGEN WANE
CONSIDERABLY. PER RADAR AND SHORT TERM GUIDANCE (RUC/HRRR/NAM)
TRENDS...STILL APPEAR THE "BEST" SNOWFALL WILL FALL BETWEEN ROUGHLY
M-32 AND M-72...WHERE PERHAPS AN INCH OR TWO WILL BE POSSIBLE AS
BEST MID LEVEL OMEGA BRIEFLY BISECTS A RATHER DEEP DGZ (I.E.
SLIGHTLY BETTER RATIOS). PROBABLY NOT LOOKING AT MUCH LEFT OF THIS
SNOW BAND AFTER 18Z...THOUGH THE CHANCES ARE NOT TOTALLY ZERO ACROSS
THE SOUTHERN COUNTIES...WHERE WILL MAINTAIN A SMALL CHANCE FOR SOME
LIGHTER SNOW SHOWERS. OTHERWISE...FOCUS SHIFTS TO LAKE EFFECT
POTENTIAL AS COLDER AIR GRADUALLY SEEPS INTO THE AREA...WITH H85
TEMPS SETTLING IN AROUND -13C ON LAKE SUPERIOR TO -10C OVER LAKE
MICHIGAN. MOISTURE PROFILES NOTHING TERRIBLY IMPRESSIVE IN EITHER
LOCATION...THOUGH OVERLAKE INSTABILITY AND THUS LAKE-INDUCED
BOUNDARY LAYER DEEPER ON LAKE SUPERIOR. HOWEVER...VEERING LOW LEVEL
FLOW PROFILES MORE NORTHERLY SUPPORT BEST CHANCES ONLY ACROSS FAR
NORTHWEST CHIPPEWA COUNTY WHERE WILL CARRY A LIKELY POP (WITH ACCUMS
LESS THAN AN INCH). FARTHER SOUTH...SIMILAR FLOW REGIME WILL GIVEN
AT LEAST A SMALL CHANCE FOR SOME LIGHT SNOW SHOWERS VICINITY OF
GRAND TRAVERSE BAY...THOUGH LESS THAN STELLAR INSTABILITY AND CLOUD
TOP TEMPS ONLY AROUND -10C JUST DON`T DO MUCH TO BOLSTER ANY
CONFIDENCE ABOUT A CHANCE POP. HIGH TEMPS TO REMAIN A FEW DEGREES
ABOVE NORMAL...WITH READINGS SLOWLY FALLING THROUGH THE AFTERNOON
AND EARLY EVENING.
LAWRENCE
&&
.LONG TERM.../ISSUED AT 355 AM/...TONIGHT AND BEYOND
RATHER ACTIVE NORTHERN GREAT LAKES WEATHER REGIME EXPECTED THROUGH
CHRISTMAS DAY...AND PERHAPS BEYOND...THOUGH WITH NO MAJOR WEATHER
SYSTEMS AFFECTING THE AREA. STILL...DOES APPEAR AT LEAST A FEW
CHANCES FOR ACCUMULATING SNOW WILL EXIST HEADING INTO CHRISTMAS DAY.
FOR TONIGHT...COLDEST OF THE AIR ARRIVES...WITH H85 TEMPS DIPPING
TOWARD -15C...ALL WHILE ELONGATED LOW LEVEL RIDGING ATTEMPTS TO
BUILD THROUGH THE REGION. WHILE SETUP FOR LAKE EFFECT FROM A LAKE
INSTABILITY STANDPOINT LOOKS GREAT...LACK OF DEEPER MOISTURE...LOW
INVERSION HEIGHTS...AND RATHER LIGHT (AND THUS MESOSCALE-DOMINATED)
BOUNDARY LAYER FLOW REGIME WILL NOT WORK IN OUR FAVOR. BUBBLE HIGH
SETUP INTO ONTARIO SHOULD SUPPORT A DECENT DRAINAGE FLOW LATER
TONIGHT...ACTING TO FORCE BEST POTENTIAL FOR LAKE SNOWS WEST OF
CHIPPEWA COUNTY...THOUGH PERHAPS SETTING UP A LOCALIZED STRONGER
CONVERGENCE AXIS SOMEWHERE JUST WEST OF WHITEFISH POINT. SAID
DRAINAGE FLOW MAY ALSO ACT TO KICK SOME LAKE SNOW SHOWERS DEEPER
INTO PORTIONS OF NORTHEAST LOWER FOR A TIME. BEST CHANCES FOR SNOW
SHOWERS ACTUALLY APPEAR TO BE IN THE VICINITY OF GRAND TRAVERSE
BAY...WHERE MEAN LOW LEVEL NORTH/NORTHEAST (020 DEGREES) FLOW IN
COMBINATION WITH LONGER FETCH AND POSSIBLY SOME LAKE SUPERIOR
CONNECTION MAY BRING A COUPLE INCHES...MOST LIKELY INTO LEELANAU/
NORTHERN GRAND TRAVERSE COUNTIES. AS FOR LOWS...SHOULD BE A COLD
NIGHT FOR AREAS ALONG AND EAST OF I-75 IN EASTERN UPPER WITH
DRAINAGE FLOW SETUP...AND COULD SEE SOME SINGLE DIGIT READINGS
ACROSS INTERIOR NORTHERN LOWER AS WELL...SHOULD CLOUDS CLEAR UNDER
NORTH FLOW REGIME.
LAKE SNOW SHOWERS SHOULD WIND DOWN FRIDAY MORNING WITH SHARPLY
BACKING LOW LEVEL FLOW AND LOSS OF OVERLAKE INSTABILITY PER QUICK
PUSH OF WARM ADVECTION IN ADVANCE OF SHARPENING UPPER WAVE CROSSING
WESTERN LAKE SUPERIOR. SAID WAVE STILL FCST TO DROP BASICALLY
OVERHEAD FRIDAY EVENING...WITH QUICK SHOT OF DEEP LAYER QG-UPWARD
FORCING AND STRONG ISENTROPIC UPGLIDE ACTING TO ADVANCE AN AXIS OF
SNOW THROUGH ALL OF EASTERN UPPER AND LIKELY MUCH OF NORTHERN LOWER.
WILL PROBABLY SEE A LAKE MICHIGAN CONTRIBUTION AS WELL AS MARGINAL
INSTABILITY REMAINS OUT AHEAD OF THIS FEATURE...AND WILL CONTINUE TO
PAINT A GENERAL 2 TO 3 INCHES FROM THE STRAITS ON NORTH...TAPERING
TO LESS THAN A HALF INCH SOUTH OF AN ALPENA TO CADILLAC LINE WITH
LACK OF LAKE HELP AND WHERE PRONOUNCED DRY WEDGE BELOW 750MB WILL
TAKE SOME TIME TO OVERCOME.
TRANSIENT LOW LEVEL SHORTWAVE RIDGING ARRIVING IN THE WAKE OF THIS
SYSTEM EARLY SATURDAY ALONG WITH STARK WARM ADVECTION OUT AHEAD OF
NEXT APPROACHING UPPER WAVE SHOULD END ANY THREAT FOR LAKE SNOW
SHOWERS BEHIND THE INITIAL DEPARTING SHORTWAVE. THIS UPPER WAVE
SATURDAY AFTERNOON REALLY DOESN`T HAVE MUCH TO WORK WITH IN TERMS OF
MOISTURE...SO PERHAPS JUST A BRIEF INCREASE IN CLOUDS. NEXT...WE SET
OUR EYES ON THE NEXT UPPER WAVE AMPLIFYING INTO THE REGION LATER
SATURDAY NIGHT...WHICH SHOULD BEGIN TO SPREAD SOME LIGHT SNOW ACROSS
THE CENTRAL/EASTERN U.P. UP THROUGH CHRISTMAS MORNING.
LAWRENCE
REST OF THE FORECAST...REASONABLY VIGOROUS SHORTWAVE WILL DIG ACROSS
THE FORECAST AREA ON XMAS MORNING. DELTA T/S OF 12/13C ARE MARGINAL
FOR ANY LAKE ENHANCEMENT FOR THE BULK OF THE EVENT...COLD ADVECTION
DEVELOPS IN THE AFTERNOON JUST ABOUT AS DEEP MOISTURE PULLS OUT.
BUT...WITH SLIGHTLY BETTER MODEL AGREEMENT IN TIMING THIS FEATURE
IN...WILL GO AHEAD AND BUMP POPS UP JUST A BIT. SYSTEM HAS DECENT
DYNAMICS BUT IS (LIKE ALL WAVES IN THIS TIGHTLY-PACKED WAVE TRAIN)
SOMEWHAT MOISTURE-DEFICIENT. WOULD LEAN TOWARD ACCUMS OF 2 INCHES OR
LESS...THOUGH WITH SOME LOW-END BLOWING-DRIFTING WITH DEVELOPING
GUSTY NW WINDS. ANY SNOW MAY BE ON THE SLOPPY SIDE EARLY NEAR THE
LAKE MI COAST. ANY LINGERING LAKE EFFECT EARLY XMAS NIGHT WILL
QUICKLY GET CRUSHED BY DEEP SUBSIDENCE/DRYING/WARMING.
WX SYSTEMS WILL CONTINUE TO COME FAST AND NOT-AT-ALL-FURIOUS IN
RAPID WNW FLOW ALOFT. HOWEVER...MODEL TIMING DIFFERENCES ARE GROWING
WITH TIME...AND DON/T HAVE MUCH CONFIDENCE IN ANY ONE SOLUTION. BUT
EVEN THE FAST GFS WOULD ALLOW FOR A DRY/MILD MONDAY. GEM/ECMWF HOLD
OFF ON ANY REAL FORCING UNTIL TUESDAY...WHILE THE GFS BRINGS IN A
LEAD IMPULSE MONDAY NIGHT. PREFER THE GREATER RUN-TO-RUN CONSISTENCY
OF THE GEM/ECMWF CAMP...KEEPING MONDAY NIGHT LARGELY DRY...BUT
RETURNING A CHANCE OF SNOW IN SPOTS (MAINLY EASTERN UPPER MI) FOR
TUESDAY. LARGELY DRY FOR WEDNESDAY...AS WE FIND OURSELVES BRIEFLY
BETWEEN SYSTEMS AGAIN.
TEMPS ABOVE CLIMO THROUGHOUT...ESPECIALLY AT NIGHT AFTER SUNDAY
NIGHT. XMAS DAY WILL LIKELY FEATURE A NON-DIURNAL CURVE...WITH AN
EARLY HIGH AND FALLING (BUT NOT CRATERING) TEMPS IN THE AFTERNOON.
JZ
&&
.MARINE.../ISSUED AT 355 AM/
QUITE CHANGEABLE WEATHER CONDITIONS ARE EXPECTED OVER THE NEXT
SEVERAL DAYS...AS NUMEROUS WAVES OF LOW PRESSURE TRACK THROUGH THE
NORTHERN GREAT LAKES. WINDS WILL BY FAR BE THE LIGHTEST TODAY
THROUGH THE FIRST HALF OF FRIDAY...AS HIGH PRESSURE SLOWLY WORKS ITS
WAY THROUGH THE REGION...PROVIDING A MAINLY NORTHERLY FLOW REGIME.
WINDS WILL BACK QUICKLY TO THE SOUTHWEST AND INCREASE FRIDAY
AFTERNOON AND EVENING AS A CLIPPER SYSTEM CROSSES THE WATERS...WITH
SMALL CRAFT CONDITIONS BRIEFLY POSSIBLE. THEREAFTER...WINDS ARE
EXPECTED TO DIMINISH FOR A BRIEF TIME INTO EARLY SATURDAY...BEFORE
STRENGTHENING ONCE AGAIN SATURDAY NIGHT AS THE NEXT WAVE OF LOW
PRESSURE DROPS INTO THE GREAT LAKES. SMALL CRAFT ADVISORY OR EVEN
LOW GALE CONDITIONS ARE POSSIBLE DURING THIS TIME AS WELL.
LOOKING AHEAD...THIS GENERAL PATTERN WILL CONTINUE INTO EARLY NEXT
WEEK...WITH THE POTENTIAL FOR WIDESPREAD GALES LATER MONDAY INTO
TUESDAY AS A STRONG PUSH OF MUCH WARMER AIR ARRIVES.
LAWRENCE
&&
.AVIATION.../ISSUED AT 1158 PM/...VALID FOR 06Z TAFS
NARROW BAND OF SNOWFALL EXPECTED TO EXPAND SOUTHEAST ACROSS THE TAF
SITES THIS MORNING AS MID LEVEL FGEN RESPONSE INTENSIFIES AND COLD
FRONT PASSES THROUGH THE REGION. CIGS AND VIS EXPECTED TO TANK
RATHER QUICKLY WITHIN THIS BAND...WITH TRENDS SUPPORTING STEADIEST
AND "HEAVIEST" SNOWS IMPACTING TVC AND MBL. WILL CONTINUE TO DROP
VIS TO 2 TO 3 MILES ALL LOCATIONS (LOWEST AT AFOREMENTIONED
TERMINALS)...ALTHOUGH LIKELY SHORT DURATION HEAVIER SNOW BURSTS WILL
LOWER THIS EVEN FURTHER. GIVEN UNCERTAINTY...WILL ATTEMPT NO BETTER
TEMPORAL AND SPATIAL RESOLUTION...AND WAIT FOR DEVELOPMENT OF
ANTICIPATED SNOW BAND FOR POSSIBLE HIGHER IMPACT TEMPO INCLUSIONS.
BAND IS EXPECTED TO WEAKEN RATHER QUICKLY THURSDAY MORNING...LEAVING
BEHIND AN MVFR CLOUD DECK...WITH THIS PERSISTING INTO THURSDAY
EVENING.
MSB
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
521 AM CST THU DEC 22 2011
.UPDATE...
.AVIATION...
MIXED MVFR/VFR LOCAL IFR CONDITIONS WILL IMPROVE TO VFR FROM
NORTH TO SOUTH THIS MORNING. SATELLITE TIMING TOOLS INDICATE VFR
COULD BE WIDESPREAD BY 15Z AND CERTAINLY BY 18Z AS PACIFIC HIGH
PRESSURE AND DRY AIR AT THE LOWER LEVELS SWEEPS IN.
VFR IS EXPECTED ALL AREAS 18Z THROUGH 12Z FRIDAY AS HIGH PRESSURE
DRIFTS SOUTH ACROSS KS/COLO AND LOW PRESSURE DEEPENS ACROSS SRN
CANADA.
&&
.PREV DISCUSSION... /ISSUED 358 AM CST THU DEC 22 2011/
DISCUSSION...
NEAR TERM MODEL SOLUTIONS CONTINUE TO INDICATE AN
ABRUPT END TO THE SNOWFALL AS DRIER AIR AND DIMINISHING FORCING WILL
EFFECTIVELY END SNOW PRODUCTION BEFORE SUNRISE FOR MOST OF THE
FORECAST AREA. THE LONE EXCEPTIONS WILL BE THE FAR SOUTHERN
COUNTIES...WHERE MODEL CONSENSUS WOULD SUGGEST -SN OR FLURRIES UP
THROUGH 15Z TODAY. FLURRIES ALSO MAY BE POSSIBLE ACROSS THE
SAND HILLS THROUGH MID MORNING AS THE 22.05Z HRRR INDICATES CSI
BANDING IN THE WAKE OF THE DEPARTING SYSTEM. CROSS SECTIONS DO
REVEAL A SHORT PERIOD WHERE MOMENTUM LINES RUN PARALLEL TO THE
THETA SURFACES...SO WILL NOT RULE OUT A STRAY FLURRY OR SNOW
SHOWER...BUT GIVEN RECENT RADAR TRENDS AND THE DRYING...FEEL THAT
THE THREAT WILL BE MINIMAL AT BEST. OTHERWISE...CAA AND
SNOW PACK...ALBEIT SLIGHT SNOW PACK...WITH HELP KEEP TEMPERATURES
BELOW AVERAGE THIS AFTERNOON...WITH GENERAL MODEL CONSENSUS
SUGGESTING HIGHS IN THE LOWER 30S. DID UNDERCUT GUIDANCE SLIGHTLY
ACROSS THE WEST...WHERE A SLIGHTLY DEEPER SNOW PACK RESIDES...MID
TO UPPER 20S SHOULD BE FINE. FOR TONIGHT..WESTERLY DOWN SLOPING
FLOW DEVELOPS OVERNIGHT AS CANADIAN HIGH PRESSURE SETTLES ACROSS
THE DEEPER SNOW PACK OF EASTERN COLORADO AND WESTERN
KANSAS/OKLAHOMA. GUIDANCE IS SUGGESTING RATHER COLD TEMPERATURES
ACROSS THE CWA...WITH POSSIBLY SUB ZERO READINGS ACROSS THE FAR
WESTERN ZONES. NOT READY TO LOWER MINS THAT MUCH...ESPECIALLY
SINCE WEAK WAA AND DOWN SLOPE FLOW SHOULD PREVAIL. AS OF
NOW...SINGLE DIGIT LOWS LOOK APPROPRIATE ACROSS THE WESTERN HALF
OF THE CWA...WITH LOW TO MID TEENS ACROSS THE EAST. ON
FRIDAY...RISING HEIGHTS ASSOCIATED WITH SHORTWAVE RIDGING WILL
WORK IN CONCERT WITH DOWN SLOPING FLOW TO PUSH TEMPERATURES UP TO
NEAR CLIMO...WITH HIGHS BACK INTO THE UPPER 30S...POSSIBLY IN THE
LOW 40S FOR THE WARM BIASED LOCATIONS.
FOR THE HOLIDAY WEEKEND AND BEYOND. NORTHWESTERLY FLOW WILL BECOME
ESTABLISHED ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS AS RIDGING
BUILDS ACROSS THE WESTERN CONUS. THE NORTHERN STREAM REMAINS
ACTIVE...WITH INDICATIONS OF SEVERAL SHORTWAVES PUSHING SOUTHEAST
FROM THE CANADIAN ROCKIES TOWARD THE GREAT LAKES REGION...BUT A LACK
OF KINEMATIC FORCING WILL KEEP PRECIPITATION OUT OF THE FORECAST
THROUGH MIDWEEK. AS FOR TEMPERATURES...A GRADUAL WARMING TREND IS
EXPECTED THROUGH EARLY NEXT WEEK. HIGHS SATURDAY AND CHRISTMAS DAY
SHOULD CLIMB ABOVE 40F AS INCREASING THICKNESS BUILDS OVER WESTERN
NEBRASKA. MONDAY APPEARS TO BE THE WARMEST DAY YET...AS H85 TEMPS
FLIRT WITH 10C AND DOWN SLOPING FLOW HELP WARM TEMPS AOA 50F. LOWS
THROUGH THE EXTENDED LOOK TO REMAIN ABOVE SEASONAL NORMS...WITH MID
TEENS AND 20S EXPECTED.
AVIATION...
MIXED MVFR/VFR LOCAL IFR CONDITIONS WILL RAPIDLY IMPROVE TO VFR FROM
NORTH TO SOUTH THIS MORNING. VFR COULD BE WIDESPREAD BY 12Z AND
CERTAINLY BY 15Z AS PACIFIC HIGH PRESSURE AND DRY AIR AT THE LOWER
LEVELS SWEEPS IN.
VFR IS EXPECTED ALL AREAS 15Z THROUGH 12Z FRIDAY AS HIGH PRESSURE
DRIFTS SOUTH ACROSS KS/COLO AND LOW PRESSURE DEEPENS ACROSS SRN
CANADA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...JACOBS
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
930 AM EST THU DEC 22 2011
.SYNOPSIS...
UNSEASONABLE WARMTH WILL CONTINUE TODAY WITH ONLY A FEW SHOWERS...
ESPECIALLY INLAND. A COLD FRONT WILL MOVE ACROSS THE AREA FRIDAY
BRINGING WITH IT A BETTER CHANCE OF SHOWERS. CHRISTMAS EVE WILL BE
DRY WITH WET WEATHER EXPECTED CHRISTMAS DAY. NEXT WEEK LOOKS TO BE
DRY WITH SEASONABLE TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM THURSDAY...SO FAR NO ADJUSTMENTS TO THE FORECAST HAVE
BEEN NEEDED AND LOOKING FORWARD NONE ARE ANTICIPATED. EARLY VISIBLE
SATELLITE IMAGE SUGGESTS THAT THE MAIN THING TO BE ON THE LOOK OUT
FOR WILL BE BREAKS IN THE CLOUDS THAT WIND UP LASTING LONG ENOUGH IN
A GIVEN PLACE THAT COULD BUST THE TEMPERATURE FORECAST. ONCE AGAIN
HOWEVER THIS CURRENTLY APPEARS UNLIKELY. PREV DISCUSSION FOLLOWS...
AS OF 630 AM THURSDAY...TODAY IS THE FIRST DAY OF WINTER AND WILL
SEE SOME OF THE LOWEST SUN ANGLES (32-33 DEGREES AT SOLAR NOON)...
THE SHORTEST DAY LENGTH (ABOUT 9 HOURS 52 MINUTES)...AND THE LEAST
POTENTIAL SOLAR ENERGY OF THE ENTIRE YEAR. HOWEVER OUR AIRMASS IS
SUBTROPICAL IN ORIGIN AND WILL YIELD HIGH TEMPERATURES MORE TYPICAL
OF MID-APRIL THAN MID-DECEMBER. SOUTHERLY FLOW BETWEEN HIGH PRESSURE
WELL OFFSHORE AND A COLD FRONT SNAKING FROM COASTAL NEW ENGLAND
THROUGH THE SOUTHERN APPALACHIANS WILL CONTINUE TO BRING THIS WARM
AND HUMID AIR INTO THE CAROLINAS THROUGH TONIGHT.
PLENTY OF STRATOCUMULUS BETWEEN 3000-6000 FT AGL WILL MOVE ACROSS
THE AREA TODAY. EVEN WITH CONSIDERABLE CLOUDINESS ENOUGH SUNSHINE
SHOULD GET THROUGH TO PRODUCE HIGHS IN THE 71-75 RANGE...JUST
SLIGHTLY ABOVE GFS/NAM MOS CONSENSUS. WITH 11Z TEMPERATURES IN THE
LOWER TO MIDDLE 60S IT WON`T TAKE MUCH SUN TO REACH THESE HIGH
TEMPERATURES! THE ONLY PORTION OF OUR FORECAST AREA NOT EXPECTED TO
SHARE THE WARMTH TODAY IS THE IMMEDIATE COASTLINE WHERE A
SOUTH-SOUTHWEST (220 DEGREE) WIND IS BLOWING ONSHORE. THIS INCLUDES
THE BEACHES BETWEEN MYRTLE BEACH AND BALD HEAD ISLAND...PLUS MOST OF
THE PENDER COUNTY BEACHES. HERE COOLER MARINE AIR WILL KEEP
TEMPERATURES IN THE 60S TODAY...ALONG WITH THE POTENTIAL FOR SOME
SEA FOG AS DEWPOINTS RISE IN THE LOWER TO MID 60S THIS AFTERNOON AND
EVENING.
A WEAK UPPER LEVEL DISTURBANCE MOVING NORTH OUT OF GEORGIA WILL HELP
SUSTAIN AN AREA OF SHOWERS ACROSS EAST-CENTRAL SOUTH CAROLINA AND
ADJACENT PORTIONS OF NORTH CAROLINA THIS MORNING. CONVECTIVE
POTENTIAL DUE TO SURFACE HEATING IS VERY LOW GIVEN THE SHALLOW MIXED
LAYER (2000-3000 FT) EXPECTED TO DEVELOP. IF ANY SHOWERS WERE TO
DEVELOP LATER TODAY...THE AREA ALONG AND WEST OF I-95 IS PREFERRED
DUE TO THE RELATIVE PROXIMITY OF AN UPPER DISTURBANCE AFTER 18Z THAT
MOVES THROUGH THE WESTERN CAROLINAS. SHOWER CHANCES WILL INCREASE A
LITTLE MORE LATE THIS EVENING AS A 300 MB JET STREAK MOVES NORTH OF
THE AREA AND CREATES AN AREA OF DIFLUENCE AND INFERRED LIFT ACROSS
THE CENTRAL CAROLINAS. OUR POPS TONIGHT RANGE FROM 20 ALONG THE
COAST TO 40 IN THE LUMBERTON/BENNETTSVILLE AREA...WITH LOWS EXPECTED
TO REMAIN IN THE 59-63 RANGE FOR MOST AREAS.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...PROSPECTS FOR AN APPRECIABLE OR AT LEAST A
"WETTING` RAIN EVENT FOR FRIDAY HAVE TAKEN A STEP BACK WITH THE
LATEST MODEL CYCLES THIS MORNING. COLD FRONT MOVING ACROSS THE
AREA REMAINS ON SCHEDULE BUT ANY MID LEVEL FORCING HAS WEAKENED
WITH A BROAD EXIT REGION OF THE 300MB JET. WE WILL PROBABLY SEE
SEVERAL PATCHES OF LIGHT RAIN SIMILAR TO WEDNESDAY BEFORE 1800 UTC
FRIDAY. CHRISTMAS EVE COULD OFFER A LITTLE SUNSHINE ALTHOUGH WITH
THE PERSISTENT MOISTURE LADEN SOUTHWEST FLOW MID LEVEL SCATTERED
TO BROKEN CEILINGS ARE PROBABLE. TAKING A QUE FROM WEDNESDAYS
EVENTS...LEANED TOWARD THE COOLER MET NUMBERS FOR HIGHS FRIDAY AND
A BLEND SATURDAY AS TEMPERATURES REMAIN ELEVATED FROM SEASONAL
NORMS.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...THE EXTENDED PACKAGE THIS MORNING IS
ESSENTIALLY AN UPDATE OF THE PREVIOUS FORECAST AS THE MEDIUM RANGE
MODELS CONTINUE TO STRUGGLE WITH THE SCENARIO AND TIMING OF PACIFIC
ENERGY. THIS WILL BE THE IMPETUS THAT KICKS OUT WHAT SHOULD BE A
SHEARING SHORTWAVE FROM THE SEEMINGLY PERSISTENT TROUGH ACROSS THE
SOUTHWEST. THERE IS SOME CONSENSUS BUILDING THAT THE SYSTEM WILL BE
WEAK AND A QUICK MOVER. THE FORECAST FOR CHRISTMAS DAY IS ISNT
LOOKING GREAT. DID INCREMENTALLY INCREASE POPS TO REFLECT A SLIGHT
INCREASE IN CONFIDENCE. OTHERWISE NO OTHER CHANGES. DIDNT WANT TO
GET INTO TRYING TO RESOLVE ANY ISSUES FOR LATE IN THE PERIOD WHEN
THE MODELS CONTINUE TO STRUGGLE WITH EARLIER FEATURES.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 12Z...LOW CONFIDENCE EARLY DUE TO POTENTIAL IFR
CIGS...BECOMING MODERATE CONFIDENCE THIS AFTN AS MVFR/VFR DEVELOPS.
THE COASTAL CAROLINAS REMAIN IN MOIST SWLY FLOW BETWEEN HIGH
PRESSURE OFFSHORE AND A COLD FRONT APPROACHING FROM THE WEST. THIS
HIGH DEWPOINT AIR IS CREATING HIGHLY VARIABLE BKN CIGS WHICH WILL
PERSIST THROUGH THE VALID PERIOD.
THE INLAND TERMINALS...WHICH ARE CLOSER TO SATURATION IN THE LOWEST
LEVELS...MAY SEE SOME IFR THIS MORNING. ALTHOUGH ONLY THE HRRR IS
DEPICTING IFR CIGS...THIS GUIDANCE HAS DONE WELL RECENTLY AND IFR IS
DEVELOPING UPSTREAM. CONFIDENCE IS RELATIVELY HIGHER AT LBT WHERE
TEMPO IFR HAS BEEN INTRODUCED...BUT IFR MAY REMAIN JUST WEST.
OTRW...BOTH FLO AND LBT WILL REMAIN MVFR THROUGH AT LEAST EARLY
AFTN. THE COASTAL TERMINALS WILL SEE SOME MVFR THIS MORNING BEFORE
CIGS RISE DIURNALLY WITH BKN VFR STRATOCU EXPECTED ALL DAY WITH SW
WINDS AROUND 10 KTS GUSTING TO 15-20 KTS AT THE COAST. THE SW WINDS
AND MOISTURE RICH AIR MAY CREATE SOME SEA FOG AT THE MYRTLES
TODAY...BUT CONFIDENCE NOT HIGH ENOUGH TO MENTION ATTM.
CIGS WILL LOWER DIURNALLY OVERNIGHT WITH MVFR AGAIN POSSIBLE.
SHOWERS ALONG THE COLD FRONT WILL APPROACH THE INLAND TERMINALS LATE
IN THIS VALID PERIOD...AND HAVE VCSH AT LBT/FLO AFTER MIDNIGHT.
WINDS WILL PERSIST FROM THE SW AROUND 10 KTS AS GRADIENT REMAINS
TIGHT AHEAD OF THE FRONT.
EXTENDED OUTLOOK...SCATTERED SHOWERS WITH ASSOCIATED MVFR/IFR
FRIDAY. VFR SATURDAY. MORE RAIN AND IFR POSSIBLE SUNDAY AND MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM THURSDAY...SCEC HEADLINES LOWERED AS ANTICIPATED AS
SEAS EVEN AS FAR OUT AS 41013 NOW SETTLED TO 5.5 FT...PROBABLY
TRANSLATING TO ABOUT 4 FT OUT NEAR 20 NM IN THE COAST-PARALLEL SWRLY
FLOW. A FEW SHOWERS ALONG THE WEST WALL EXPECTED TO GENERALLY REMAIN
EAST OF THE FORECAST AREA. SUSPECT THAT MAIN FORECAST ISSUE FOR THE
PERIOD WILL BE MONITORING VIS SAT IMAGERY AND NEW GUIDANCE FOR SEA
FOG POTENTIAL.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...BIG STORY WILL BE THE WIND SHIFT FOR FRIDAY
AFTERNOON AS THE FRONT MOVES ACROSS THE WATERS. WINDS VEER FROM
SOUTHWEST TO NORTHEAST. WITHOUT ANY SIGNIFICANT COLD AIR
ADVECTION...SPEEDS WILL BE LIMITED TO A MAX OF 15-20 KNOTS MAINLY
FOR A FEW HOURS SATURDAY AFTERNOON. HIGH PRESSURE WEAKENS AND
SETTLES SOUTH BY EARLY SUNDAY ALLOWING FOR A MORE EASTERLY FLOW. THE
LATEST SWAN IS ADVERTISING 3-5 FEET FRIDAY DROPPING OT 2-4 FEET
SATURDAY.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 300 AM THURSDAY...PRESSURE PATTERN BECOMES VERY DIFFUSE AS A
MID LEVEL SYSTEM ROLLS ACROSS SUNDAY. IN THE WAKE OF THIS SYSTEM A
WEST TO NORTHWEST FLOW DEVELOPS AS HIGH PRESSURE BUILDS IN FROM
THE MISSISSIPPI VALLEY. WIND SPEEDS INCREASE TO NEAR 20 KNOTS EARLY
MONDAY. WITH THE OFFSHORE FLOW EXPECT SEAS OF 2-4 FEET WITH THE
HIGHER VALUES FURTHER ACROSS THE OUTER WATERS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...MBB
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...JDW
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
635 AM EST THU DEC 22 2011
.SYNOPSIS...
UNSEASONABLE WARMTH WILL CONTINUE TODAY WITH ONLY A FEW SHOWERS...
ESPECIALLY INLAND. A COLD FRONT WILL MOVE ACROSS THE AREA FRIDAY
BRINGING WITH IT A BETTER CHANCE OF SHOWERS. CHRISTMAS EVE WILL BE
DRY WITH WET WEATHER EXPECTED CHRISTMAS DAY. NEXT WEEK LOOKS TO BE
DRY WITH SEASONABLE TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM THURSDAY...TODAY IS THE FIRST DAY OF WINTER AND WILL
SEE SOME OF THE LOWEST SUN ANGLES (32-33 DEGREES AT SOLAR NOON)...
THE SHORTEST DAY LENGTH (ABOUT 9 HOURS 52 MINUTES)...AND THE LEAST
POTENTIAL SOLAR ENERGY OF THE ENTIRE YEAR. HOWEVER OUR AIRMASS IS
SUBTROPICAL IN ORIGIN AND WILL YIELD HIGH TEMPERATURES MORE TYPICAL
OF MID-APRIL THAN MID-DECEMBER. SOUTHERLY FLOW BETWEEN HIGH PRESSURE
WELL OFFSHORE AND A COLD FRONT SNAKING FROM COASTAL NEW ENGLAND
THROUGH THE SOUTHERN APPALACHIANS WILL CONTINUE TO BRING THIS WARM
AND HUMID AIR INTO THE CAROLINAS THROUGH TONIGHT.
PLENTY OF STRATOCUMULUS BETWEEN 3000-6000 FT AGL WILL MOVE ACROSS
THE AREA TODAY. EVEN WITH CONSIDERABLE CLOUDINESS ENOUGH SUNSHINE
SHOULD GET THROUGH TO PRODUCE HIGHS IN THE 71-75 RANGE...JUST
SLIGHTLY ABOVE GFS/NAM MOS CONSENSUS. WITH 11Z TEMPERATURES IN THE
LOWER TO MIDDLE 60S IT WON`T TAKE MUCH SUN TO REACH THESE HIGH
TEMPERATURES! THE ONLY PORTION OF OUR FORECAST AREA NOT EXPECTED TO
SHARE THE WARMTH TODAY IS THE IMMEDIATE COASTLINE WHERE A
SOUTH-SOUTHWEST (220 DEGREE) WIND IS BLOWING ONSHORE. THIS INCLUDES
THE BEACHES BETWEEN MYRTLE BEACH AND BALD HEAD ISLAND...PLUS MOST OF
THE PENDER COUNTY BEACHES. HERE COOLER MARINE AIR WILL KEEP
TEMPERATURES IN THE 60S TODAY...ALONG WITH THE POTENTIAL FOR SOME
SEA FOG AS DEWPOINTS RISE IN THE LOWER TO MID 60S THIS AFTERNOON AND
EVENING.
A WEAK UPPER LEVEL DISTURBANCE MOVING NORTH OUT OF GEORGIA WILL HELP
SUSTAIN AN AREA OF SHOWERS ACROSS EAST-CENTRAL SOUTH CAROLINA AND
ADJACENT PORTIONS OF NORTH CAROLINA THIS MORNING. CONVECTIVE
POTENTIAL DUE TO SURFACE HEATING IS VERY LOW GIVEN THE SHALLOW MIXED
LAYER (2000-3000 FT) EXPECTED TO DEVELOP. IF ANY SHOWERS WERE TO
DEVELOP LATER TODAY...THE AREA ALONG AND WEST OF I-95 IS PREFERRED
DUE TO THE RELATIVE PROXIMITY OF AN UPPER DISTURBANCE AFTER 18Z THAT
MOVES THROUGH THE WESTERN CAROLINAS. SHOWER CHANCES WILL INCREASE A
LITTLE MORE LATE THIS EVENING AS A 300 MB JET STREAK MOVES NORTH OF
THE AREA AND CREATES AN AREA OF DIFLUENCE AND INFERRED LIFT ACROSS
THE CENTRAL CAROLINAS. OUR POPS TONIGHT RANGE FROM 20 ALONG THE
COAST TO 40 IN THE LUMBERTON/BENNETTSVILLE AREA...WITH LOWS EXPECTED
TO REMAIN IN THE 59-63 RANGE FOR MOST AREAS.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...PROSPECTS FOR AN APPRECIABLE OR AT LEAST A
"WETTING` RAIN EVENT FOR FRIDAY HAVE TAKEN A STEP BACK WITH THE
LATEST MODEL CYCLES THIS MORNING. COLD FRONT MOVING ACROSS THE
AREA REMAINS ON SCHEDULE BUT ANY MID LEVEL FORCING HAS WEAKENED
WITH A BROAD EXIT REGION OF THE 300MB JET. WE WILL PROBABLY SEE
SEVERAL PATCHES OF LIGHT RAIN SIMILAR TO WEDNESDAY BEFORE 1800 UTC
FRIDAY. CHRISTMAS EVE COULD OFFER A LITTLE SUNSHINE ALTHOUGH WITH
THE PERSISTENT MOISTURE LADEN SOUTHWEST FLOW MID LEVEL SCATTERED
TO BROKEN CEILINGS ARE PROBABLE. TAKING A QUE FROM WEDNESDAYS
EVENTS...LEANED TOWARD THE COOLER MET NUMBERS FOR HIGHS FRIDAY AND
A BLEND SATURDAY AS TEMPERATURES REMAIN ELEVATED FROM SEASONAL
NORMS.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...THE EXTENDED PACKAGE THIS MORNING IS
ESSENTIALLY AN UPDATE OF THE PREVIOUS FORECAST AS THE MEDIUM RANGE
MODELS CONTINUE TO STRUGGLE WITH THE SCENARIO AND TIMING OF PACIFIC
ENERGY. THIS WILL BE THE IMPETUS THAT KICKS OUT WHAT SHOULD BE A
SHEARING SHORTWAVE FROM THE SEEMINGLY PERSISTENT TROUGH ACROSS THE
SOUTHWEST. THERE IS SOME CONSENSUS BUILDING THAT THE SYSTEM WILL BE
WEAK AND A QUICK MOVER. THE FORECAST FOR CHRISTMAS DAY IS ISNT
LOOKING GREAT. DID INCREMENTALLY INCREASE POPS TO REFLECT A SLIGHT
INCREASE IN CONFIDENCE. OTHERWISE NO OTHER CHANGES. DIDNT WANT TO
GET INTO TRYING TO RESOLVE ANY ISSUES FOR LATE IN THE PERIOD WHEN
THE MODELS CONTINUE TO STRUGGLE WITH EARLIER FEATURES.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 12Z...LOW CONFIDENCE EARLY DUE TO POTENTIAL IFR
CIGS...BECOMING MODERATE CONFIDENCE THIS AFTN AS MVFR/VFR DEVELOPS.
THE COASTAL CAROLINAS REMAIN IN MOIST SWLY FLOW BETWEEN HIGH
PRESSURE OFFSHORE AND A COLD FRONT APPROACHING FROM THE WEST. THIS
HIGH DEWPOINT AIR IS CREATING HIGHLY VARIABLE BKN CIGS WHICH WILL
PERSIST THROUGH THE VALID PERIOD.
THE INLAND TERMINALS...WHICH ARE CLOSER TO SATURATION IN THE LOWEST
LEVELS...MAY SEE SOME IFR THIS MORNING. ALTHOUGH ONLY THE HRRR IS
DEPICTING IFR CIGS...THIS GUIDANCE HAS DONE WELL RECENTLY AND IFR IS
DEVELOPING UPSTREAM. CONFIDENCE IS RELATIVELY HIGHER AT LBT WHERE
TEMPO IFR HAS BEEN INTRODUCED...BUT IFR MAY REMAIN JUST WEST.
OTRW...BOTH FLO AND LBT WILL REMAIN MVFR THROUGH AT LEAST EARLY
AFTN. THE COASTAL TERMINALS WILL SEE SOME MVFR THIS MORNING BEFORE
CIGS RISE DIURNALLY WITH BKN VFR STRATOCU EXPECTED ALL DAY WITH SW
WINDS AROUND 10 KTS GUSTING TO 15-20 KTS AT THE COAST. THE SW WINDS
AND MOISTURE RICH AIR MAY CREATE SOME SEA FOG AT THE MYRTLES
TODAY...BUT CONFIDENCE NOT HIGH ENOUGH TO MENTION ATTM.
CIGS WILL LOWER DIURNALLY OVERNIGHT WITH MVFR AGAIN POSSIBLE.
SHOWERS ALONG THE COLD FRONT WILL APPROACH THE INLAND TERMINALS LATE
IN THIS VALID PERIOD...AND HAVE VCSH AT LBT/FLO AFTER MIDNIGHT.
WINDS WILL PERSIST FROM THE SW AROUND 10 KTS AS GRADIENT REMAINS
TIGHT AHEAD OF THE FRONT.
EXTENDED OUTLOOK...SCATTERED SHOWERS WITH ASSOCIATED MVFR/IFR
FRIDAY. VFR SATURDAY. MORE RAIN AND IFR POSSIBLE SUNDAY AND MONDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM THURSDAY...HIGH PRESSURE WELL OFFSHORE IS PUMPING A
WARM AND HUMID AIRMASS NORTHWARD ALONG THE CAROLINA COASTLINE. A
COLD FRONT EXTENDING FROM COASTAL NEW ENGLAND SOUTH INTO THE WESTERN
CAROLINAS WILL MOVE SLOWLY EASTWARD THROUGH TONIGHT...REMAINING
INLAND. A PERIOD OF MODERATE SOUTH-SOUTHWESTERLY FLOW YESTERDAY
BUILT SEAS TO AS HIGH AS 6 FT AT THE FRYING PAN SHOALS BUOY...AND 4
FT AT THE NEARSHORE WRIGHTSVILLE BEACH BUOY. MODELS SHOW WIND SPEEDS
SHOULD REMAIN 15 KT OR LESS THROUGH THE AFTERNOON...ALLOWING SEA
HEIGHTS TO FALL BELOW 5 FEET ACROSS THE COASTAL WATERS. WINDS ARE
HOWEVER EXPECTED TO PICK BACK UP THIS EVENING WITH THE POTENTIAL OF
A FEW 6 FT SEAS DEVELOPING WITHIN 20 MILES OF SHORE...PARTICULARLY
ACROSS THE NORTH CAROLINA WATERS. CONDITIONS ARE MARGINAL FOR A
SMALL CRAFT ADVISORY ALONG FRYING PAN SHOALS OVERNIGHT...BUT FOR NOW
WE WILL STICK WITH 15-20 KT WINDS AND 4-5 FT SEAS IN THE FORECAST.
AS MOISTURE CONTINUES TO INCREASE THERE IS SOME POTENTIAL FOR SEA
FOG TO DEVELOP THIS AFTERNOON AND TONIGHT ACROSS THE NEARSHORE
WATERS. VISIBILITIES IN ANY SEA FOG COULD BE REDUCED TO LESS THAN
ONE-HALF MILE.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...BIG STORY WILL BE THE WIND SHIFT FOR FRIDAY
AFTERNOON AS THE FRONT MOVES ACROSS THE WATERS. WINDS VEER FROM
SOUTHWEST TO NORTHEAST. WITHOUT ANY SIGNIFICANT COLD AIR
ADVECTION...SPEEDS WILL BE LIMITED TO A MAX OF 15-20 KNOTS MAINLY
FOR A FEW HOURS SATURDAY AFTERNOON. HIGH PRESSURE WEAKENS AND
SETTLES SOUTH BY EARLY SUNDAY ALLOWING FOR A MORE EASTERLY FLOW. THE
LATEST SWAN IS ADVERTISING 3-5 FEET FRIDAY DROPPING OT 2-4 FEET
SATURDAY.
LONG TERM /SUNDAY THROUGH MONDAY/...
AS OF 300 AM THURSDAY...PRESSURE PATTERN BECOMES VERY DIFFUSE AS A
MID LEVEL SYSTEM ROLLS ACROSS SUNDAY. IN THE WAKE OF THIS SYSTEM A
WEST TO NORTHWEST FLOW DEVELOPS AS HIGH PRESSURE BUILDS IN FROM
THE MISSISSIPPI VALLEY. WIND SPEEDS INCREASE TO NEAR 20 KNOTS EARLY
MONDAY. WITH THE OFFSHORE FLOW EXPECT SEAS OF 2-4 FEET WITH THE
HIGHER VALUES FURTHER ACROSS THE OUTER WATERS.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...TRA
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...JDW
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
515 AM CST THU DEC 22 2011
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
305 AM CST THU DEC 22 2011
MAIN CONCERNS WILL BE LINGERING SNOW ACROSS SOUTHERN WI INTO
NORTHEAST IA EARLY THIS MORNING...THEN SLIGHT SNOW CHANCES ACROSS
NORTHERN WISCONSIN ON FRIDAY.
RADAR AND SURFACE OBSERVATIONS SHOWING A BAND OF LIGHT SNOW
EXTENDING FROM EAST CENTRAL WISCONSIN...THROUGH SOUTHWEST WI AND
CENTRAL IA. AT THE NWS OFFICE HERE AROUND A HALF INCH HAS FALLEN SO
FAR. SHORTWAVE TROUGH PRODUCING LIFT FOR THIS SNOW WAS INDICATED ON
WATER VAPOR IMAGERY ACROSS SD/NEB. AIDING IN THE BANDING OF THIS
SNOW WAS CONFLUENT 850-700MB FLOW/WEAK FRONTOGENESIS INDICATED BY
THE RUC MODEL FROM NORTHEAST IA INTO SOUTHERN WI. LOWEST VISIBILITY
UNDER THE HIGHEST REFLECTIVITY BAND ON RADAR AROUND 1SM AT BOSCOBEL
AND MINERAL POINT WI. OTHERWISE...UNDER MOSTLY CLOUDY SKIES ACROSS
THE FORECAST AREA...TEMPERATURES AT 3 AM RANGED FROM THE MID 20S
ACROSS NORTH CENTRAL WI TO THE LOWER 30S SOUTH OF I-90.
22.00Z NCEP MODEL SUITE/29.03Z SREF IN GOOD AGREEMENT THROUGH THE
SHORT TERM.
FOR TODAY...MAIN CONFLUENT 850-700MB FLOW/FRONTOGENESIS SHIFTS
SOUTHEAST OF THE AREA BY 9 AM...BRINGING AN END TO SNOW CHANCES FOR
THE AREA. OTHERWISE...IR IMAGERY SHOWS A DECENT FIELD OF
STRATOCUMULUS ACROSS MN INTO WI...AND THIS WILL LIKELY HOLD THROUGH
MUCH OF THE MORNING...THEN START TO SCOUR OUT THROUGH THE AFTERNOON
HOURS AS A RIDGE OF HIGH PRESSURE/INCREASING SUBSIDENCE BUILDS IN
FROM THE PLAINS.
NORTHWEST FLOW ALOFT WILL BRING A FAIRLY VIGOROUS MID-LEVEL
SHORTWAVE TROUGH AND SURFACE LOW ACROSS SOUTHERN ONTARIO/LAKE
SUPERIOR REGION ON FRIDAY. NAM/GFS SHOW BEST FORCING AND CHANCES FOR
SNOW WILL BE CONFINED CLOSE TO THE TROUGH/LOW. HOWEVER...THE 29.00Z
ECMWF/GEM SHOW LIGHT QPF ALL THE WAY DOWN TO I-94. WENT WITH A
COMPROMISE AND KEPT A SMALL/SLIGHT CHANCE POP IN FOR TAYLOR COUNTY.
THE FORECAST AREA WILL THEN BE IN THE WARM SECTOR OF A LOW PRESSURE
SYSTEM PASSING THROUGH CANADA ON SATURDAY. SOUTHWEST SURFACE FLOW
AND AMPLE SUNSHINE SHOULD WARM HIGHS WELL INTO THE 30S WITH PERHAPS
A FEW READINGS AROUND THE 40 DEGREE MARK ACROSS FAR SOUTHWEST
WI/NORTHEAST IA.
.LONG TERM...CHRISTMAS DAY THROUGH WEDNESDAY
305 AM CST THU DEC 22 2011
22.00Z GFS/ECMWF IN DECENT AGREEMENT THROUGH THE LONG TERM.
A COLD FRONT WILL DROP SOUTH ACROSS THE AREA CHRISTMAS DAY...BUT
APPEARS THE BULK OF THE COLD AIR ADVECTION WILL BE ALONG/NORTHEAST
OF I-94. AS A RESULT...COULD SEE HIGHS AROUND THE 40 DEGREE MARK
AGAIN SOUTHWEST OF I-94...ESPECIALLY FROM FAR SOUTHWEST WI INTO
NORTHEAST IA. OTHERWISE...WILL PROBABLY SEE SOME BLUSTERY CONDITIONS
WITH GOOD MIXING/FAIRLY TIGHT PRESSURE GRADIENT.
FAIRLY ACTIVE ZONAL FLOW REMAINS IN PLACE WITH STORM SYSTEMS STAYING
MAINLY NORTH OF THE U.S./CANADIAN BORDER. THIS KEEPS PRECIPITATION
CHANCES NORTH OF THE AREA AND WILL CONTINUE TO PRODUCE ABOVE NORMAL
TEMPERATURES.
&&
.AVIATION...
515 AM CST THU DEC 22 2011
LATEST FOG/STRATUS SATELLITE IMAGERY POINTS TO AN AREA OF 2500-3000
FT CIGS SINKING SOUTH TOWARD KRST/KLSE...AND EXPECT THESE TO MOVE
ACROSS KRST/KLSE AROUND 12Z. RUC13/NAM12 X-SECTIONS AND BUFKIT
SOUNDINGS THEN SUGGEST THE LOW STRATUS SHOULD GRADUALLY MOVE
EAST/ERODE LATER THIS MORNING...NEAR 18Z. TRENDS LOOK ALRIGHT
COMPARED TO SATELLITE IMAGERY AND WILL KEEP TAFS TAILORED THIS WAY.
EXPECT MOSTLY VFR CONDITIONS THEN THROUGH MUCH OF THE HOLIDAY
WEEKEND AS A SPLIT UPPER LEVEL FLOW USHERS VARIOUS WEATHER SYSTEMS
NORTH AND SOUTH. WHILE PCPN IS NOT EXPECTED...THESE SYSTEMS WILL
BRINGING SOME WINDS AND PERIODS OF HIGH CLOUDINESS. THE STRONGEST
WINDS LOOK TO COME CHRISTMAS EVE-CHRISTMAS MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
305 AM CST THU DEC 22 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM... DAS
LONG TERM.... DAS
AVIATION..... RIECK
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
231 PM EST THU DEC 22 2011
.SYNOPSIS...
A SLOW MOVING COLD FRONT WILL MOVE THROUGH THE ARE LATE TONIGHT
AND EARLY FRIDAY MORNING. THE CHANCE OF SHOWERS WILL DECREASE BY
FRIDAY AFTERNOON. HIGH PRESSURE WILL BUILD IN BRIEFLY FRIDAY NIGHT
AND SATURDAY BEFORE ANOTHER WEATHER SYSTEM APPROACHES LATE
SATURDAY NIGHT AND CHRISTMAS DAY WITH ANOTHER CHANCE OF SHOWERS.
&&
.NEAR TERM /THROUGH TONIGHT/...
A WEAK COLD FRONT WILL CONTINUE TO APPROACH FROM THE NORTHWEST
WITH A CHANCE OF SHOWERS. A FEW THUNDERSTORMS ARE POSSIBLE IN THE
CSRA WHERE CONDITIONS ARE BIT MORE UNSTABLE WITH THE RUC MODEL
SHOWING LIS -2/-3 LATE THIS AFTERNOON AND EARLY THIS EVENING.
OTHERWISE...JUST SHOWERS ARE EXPECTED ELSEWHERE. ANOTHER WARM
MUGGY NIGHT IN STORE WITH LOW TEMPERATURES IN THE UPPER 50S TO
NEAR 60 DEGREES.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
THE WEAK SLOW MOVING COLD FRONT MOVES WEST TO EAST DURING THE DAY
FRIDAY AND EXITS TO THE EAST LATE IN THE DAY FRIDAY. THINK JUST A
SLIGHT CHANCE OF SHOWERS WILL COVER THE SITUATION IN MOST
LOCATIONS. ANOTHER WARM DAY FRIDAY BEFORE THE COOLER AIR ARRIVES.
WILL GO WITH HIGHS IN THE UPPER 60S TO NEAR 70. FRIDAY NIGHT AND
SATURDAY...CHRISTMAS EVE WILL SEE A BRIEF PERIOD OF DRY WEATHER AS
HIGH PRESSURE COVERS THE REGION UNTIL A GULF SYSTEM APPROACHES
LATE SATURDAY NIGHT. MORE NORMAL TEMPERATURES BY SATURDAY WITH
HIGHS IN THE LOWER TO MID 60S. LOWS SATURDAY NIGHT SHOULD BE IN
THE LOWER TO MID 40S.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
MEDIUM RANGE MODELS IN GOOD AGREEMENT MOVING GULF SYSTEM TO THE
EAST SUNDAY...CHRISTMAS DAY. DECIDED TO DOWN PLAY WEAK GULF SYSTEM
MODELS WERE HINTING AT FOR TUESDAY AND WEDNESDAY WITH UPPER FLOW
MAINLY ZONAL. THINK ANY SYSTEMS WILL MOVE QUICKLY WITH LITTLE
MOISTURE SINCE THERE ARE NO DEEP TROUGHS TO TRANSPORT MUCH
MOISTURE INTO THE REGION. SO EXPECT MAINLY HIGH PRESSURE WITH DRY
CONDITIONS MONDAY ON THROUGH THURSDAY. TEMPERATURES RETURN TO
NORMAL WITH HIGHS IN THE MID TO UPPER 50S MAYBE REACHING 60 BY
THURSDAY. OVERNIGHT LOWS IN THE MID TO UPPER 30S.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
A FEW LIGHT SHOWERS ACROSS THE NORTHERN AND CENTRAL MIDLANDS AT THE
TIME. EXPECT GENERALLY VFR WITH OCCASIONAL MVFR CONDITIONS ESPECIALLY
INVOF SHOWERS FOR THE REST OF THE AFTERNOON INTO TONIGHT. SPOTTY
SHOWERS WILL LINGER INTO THE EVENING HOURS. LOW CLOUDS WILL BE MORE
LIKELY DURING THE OVERNIGHT HOURS AS OPPOSED TO FOG DUE TO A
40 KNOT LOW-LEVEL JET ANTICIPATED TO DEVELOP LATE TONIGHT AS
SUGGESTED BY NAM BUFKIT TIME SECTIONS.
CONDITIONS SLOWLY IMPROVE AFTER 14Z AS A COLD FRONT MOVES THROUGH
THE AREA. SHOULD SEE SOME BREAKS IN THE CLOUDS BY LATE MORNING/EARLY
AFTERNOON ON FRIDAY.
EXTENDED AVIATION OUTLOOK...PERIODS OF CIG/VSBY RESTRICTIONS
EXPECTED THROUGH SATURDAY AS A SERIES OF WEATHER SYSTEMS CROSS THE
REGION.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...07
NEAR TERM...07
SHORT TERM...07
LONG TERM...07
AVIATION...22
AREA FORECAST DISCUSSION
NWS LINCOLN IL
225 PM CST THU DEC 22 2011
.DISCUSSION...
ISSUED 225 PM CST THU DEC 22 2011
19Z SFC MAP INDICATED WEAK FRONT WASHING OUT NEAR I-57 WITH LIGHT
NORTHERLY BEHIND IT. MAIN WEATHER SYSTEM ACROSS THE COUNTRY WAS
LOCATED WELL TO OUR SOUTHEAST...HOWEVER STRATIFORM RAIN SHIELD
REACHED AS FAR NORTH AS THE OHIO VALLEY...AND CLOUDS ASSOCIATED WITH
THIS FEATURE OVERSPREAD THE ENTIRE AREA. BEYOND THIS EVENING...LITTLE IN
THE WAY OF FORECAST CONCERNS WITH A DRY AND MILD PATTERN PERSISTING
THROUGH MUCH OF NEXT WEEK.
SHORT TERM...TONIGHT AND FRIDAY
A COUPLE ITEMS OF INTEREST THIS EVENING. FIRST...NORTHERN FRINGE OF
OH VALLEY RAINS LOOK TO STAY JUST SOUTHEAST OF THE LAWRENCEVILLE
AREA IN REGION OF BETTER LIFT AND MOISTURE...BUT MAY INSERT LOW CHC POPS
IN THE FAR SE BASED ON LATEST RADAR TRENDS. OTHER ITEM IS RIBBON
OF 850-700 MB FRONTOGENESIS SLIDING SE INTO NRN MO/SE IA
CURRENTLY. RADAR MOSAIC INDICATES LIGHT SNOW BAND DEVELOPING FROM
KMCI TO NEAR KIRK IN MO. LATEST RUN OF HRRR AND 12KM NAM STREAK
THIS BAND TO THE EAST...ACROSS PARTS OF CENTRAL ILLINOIS THIS
EVENING. AIRMASS IS FAIRLY DRY...SO BELIEVE MOST PRECIP GENERATION
WILL BE EATEN BY SATURATION PROCESSES. HOWEVER SOME SCATTERED
FLURRIES OR BRIEF PERIODS OF LIGHT SNOW LOOK POSSIBLE FOR ROUGHLY
THE NW HALF BEFORE FRONTOGENESIS WANES AFTER MIDNIGHT. AS THE MAIN
SYNOPTIC WEATHER FEATURES SHIFT FARTHER EAST TOMORROW...HIGH
PRESSURE WILL BEGIN TO NOSE EAST FROM THE CENTRAL PLAINS. THIS
WILL ALLOW SKIES TO CLEAR FROM WEST TO EAST FOR A WELCOME RETURN
TO SUNSHINE.
LONG TERM...SATURDAY THROUGH THURSDAY
AS HAS BEEN THE CASE MUCH OF THIS EARLY WINTER...SPLIT FLOW JET
STREAM PATTERN WILL DOMINATE THE EXTENDED PORTION OF THE FORECAST.
THIS WILL KEEP ANY ARCTIC AIR BOTTLED UP IN CANADA...AND ANY
MOISTURE-RICH SHORTWAVES WELL TO OUR SOUTH. THIS PATTERN IS
CONSISTENT WITH POSITIVE PHASES OF THE AO AND NAO...AND THESE ARE
FORECAST TO STAY POSITIVE FOR THE NEXT COUPLE WEEKS.
THE HOLIDAY WEEKEND WILL FEATURE EXCELLENT TRAVEL
CONDITIONS...WITH THE CLOSEST PRECIPITATION BEING LAKE EFFECT AND
CLIPPER SNOW FOR THE GREAT LAKES...AND RAIN FROM THE LOWER
MISSISSIPPI VALLEY INTO THE DEEP SOUTH. FOR THE LOCAL
AREA...MOSTLY CLEAR SKIES AND TEMPERATURES RUNNING 5-10 DEGREES
ABOVE NORMAL WILL DOMINATE...WITH ANY CLIPPERS STAYING WELL TO OUR
NORTHEAST. THERE IS SOME MODEL DISAGREEMENT MONDAY NIGHT...WHEN A
SOUTHERN STREAM SHORTWAVE LIFTS INTO THE MS VALLEY. PREVIOUS
GUIDANCE AND THE CURRENT GFS KEEP ANY RAIN WITH THIS FEATURE WELL
SOUTH OF THE AREA...WHILE THE LATEST ECMWF AND GEM BRING RAIN OR A
RAIN/SNOW MIX UP TO THE LOWER GREAT LAKES BY TUESDAY MORNING. FOR
NOW WILL BASE THE FORECAST ON THE MORE CONSISTENT/DRY SOLUTION BUT
KEEP AN EYE ON THIS PERIOD FOR POP ADJUSTMENT. BEYOND THIS
POTENTIAL SYSTEM...ZONAL UPPER LEVEL FLOW WILL PRODUCE DRY AND
SEASONABLY WARM WEATHER THROUGH MID-WEEK.
25
&&
.AVIATION...
ISSUED 1155 AM CST THU DEC 22 2011
MVFR VISIBILITIES FROM LIGHT FOG WILL BE VFR AT TIMES THIS AFTERNOON.
EXPECT VISIBILITIES TO LOWER THIS EVENING TO IFR WITH FOG AND CHANCE
OF LIGHT RAIN/SNOW OVER MAINLY PIA AND BMI LATER THIS AFTERNOON
INTO MID EVENING. VFR CEILINGS AT MIDDAY WITH CEILING AT OR ABOVE
12K FT TO DETERORIATE DURING THE AFTERNOON AND EVENING AS IFR
CEILINGS BEHIND A COLD FRONT NW OF THE IL RIVER SPREAD SE ACROSS
CENTRAL IL DURING THE AFTERNOON...REACHING PIA EARLY THIS AFTERNOON.
MODELS HAVE TRENDED SLOWER WITH DECREASING LOW CLOUDS DURING FRI
MORNING AND HAVE PIA SCATTER OUT AROUND 13Z...AND KEEP LOW CLOUDS
AT CMI THROUGH 18Z/FRI THOUGH LIFTING CEILINGS UP TO MVFR. LIGHT
TO CALM WINDS TO BECOME NNW BEHIND A COLD FRONT WHICH IS
APPROACHING I-55 AND TO SPREAD SE THROUGH REST OF CENTRAL IL
DURING EARLY AND MID AFTERNOON. NORTH WINDS TO INCREASE TO 8-13
KTS DURING THE AFTERNOON AND CONTINUE TONIGHT...AND BE MORE NW
AT 4-8 KTS BY FRI MORNING.
1012 MB LOW PRESSURE OVER WEST CENTRAL AL TO DEEPEN NE TO 1010 MB
OVER THE MID ATLANTIC STATES BY MIDNIGHT TONIGHT. THIS WILL KEEP
ITS LIGHT RAIN SHIELD SE OF THE CENTRAL IL AIRPORTS THIS AFTERNOON
AND EVENING. A FEW MODELS SHOW LIGHT QPF APPEARING BEHIND THE COLD
FRONT OVER THE IL RIVER VALLEY LATER THIS AFTERNOON UNTIL MID
EVENING. CONFIDENCE OF THIS OCCURING IS NOT TOO HIGH AND MAINLY
KEPT VSCH WITH TEMPO GROUPS ONLY AT PIA AND BMI FOR LIGHT OR LIGHT
SNOW. 1036 MB HIGH PRESSURE OVER WESTERN NEBRASKA TO NOSE INTO IL
BY 18Z/NOON FRI HELPING TO BRING IN DRIER AIR AND DECREASE THE LOW
CLOUDS FROM THE NW...THOUGH LIKELY LINGERING AT CMI AND POSSIBLY
DEC FRI MORNING.
HUETTL
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
321 PM CST THU DEC 22 2011
.SYNOPSIS...
SURFACE ANALYSIS AT 18Z SHOWED THE COLD FRONT THAT MOVED THROUGH
OVERNIGHT STRETCHED FROM NE TX ACROSS FAR SOUTHERN IL TO LOWER MI. A
1032 HIGH WAS BUILDING INTO SD AND NE WITH A RESULTING TIGHT
PRESSURE GRADIENT ACROSS IA PRODUCING 15 TO 20 KT NORTHERLY WINDS
OVER MUCH OF THE FORECAST AREA. SATELLITE IMAGES INDICATED THE BACK
EDGE OF THE SOUTHWARD RETREATING STRATUS DECK REACHING FROM KOTM TO
NEAR GALENA. A NARROWER...MORE CONVECTIVE LOOKING CLOUD DECK WITH
MVFR BASES WAS FURTHER NORTH ACROSS NE IA INTO WI...SHOWING SINGS OF
SHRINKING AS IT WAS ADVANCING SLOWLY SOUTHWARD. FURTHER SOUTH...AREA
RADARS SHOWED AN EXPANDING BAND OF REFLECTIVITY FROM KIRKSVILLE TO
THE QUAD CITIES...LIKELY ASSOCIATED WITH A WEAK MID LEVEL VORT
MOVING THROUGH THE AREA AND THE DEPARTING 300 MB JET CORE. 12Z
ANALYSIS REVEALED THIS JET MAX EMBEDDED IN THE UPPER LEVEL SW FLOW
AHEAD OF A NORTHERN STREAM TROUGH FROM HUDSON BAY SE INTO NEB AND A
SEPARATE...MORE CUTOFF...MID AND UPPER LEVEL CIRCULATION OVER
SOUTHERN UT.
&&
.SHORT TERM...TONIGHT AND FRIDAY...
INITIAL CONCERN IS THE POTENTIAL FOR VERY LIGHT SNOW OR FLURRIES
OVER THE NEXT SEVERAL HOURS...THEN FOCUS TURNS TO OVERNIGHT LOW
TEMPERATURES. THE EXPANDING AND INCREASING BAND OF LIGHT SNOW
MENTIONED IN THE SYNOPSIS OVER THE SOUTH HAS RECENTLY BEGUN SHOWING
UP WITH GENERALLY 1 TO 4SM -SN ALONG THE MS RIVER SOUTH OF
MUSCATINE. BASED ON VSBYS AND RADAR TRENDS...COULD SEE A QUICK
DUSTING TO POSSIBLE 1/2 INCH BEFORE THE MID LEVEL FORCING...WHICH
THE LATEST RUC AND NAM12 HAVE A ROUGH HANDLE ON...QUICKLY PUSHES
EAST BEFORE 00Z. HAVE THUS INCREASED A SMALL AREA TO LIKELY POPS FOR
LATE AFTERNOON FOR ALONG AND EAST OF THE MS RIVER SOUTH OF THE QUAD CITIES
INTO IL.
OVERNIGHT...HIGH PRESSURE RIDGE EXTENDING W-NW FROM THE HIGH PLAINS
HIGH...ALONG WITH MID LEVEL SUBSIDENCE BEHIND THE SHORTWAVE PASSING
TO THE NORTH SHOULD PUSH THE LOW CLOUDS SOUTH OF THE AREA BY
MIDNIGHT. CLEARING SKIES AND LIGHT WINDS SHOULD RESULT IN THE
COLDEST NIGHT IN SEVERAL DAYS...AND BASED ON TRAJECTORIES...LOWS
CLOSE TO GUIDANCE BLEND FROM AROUND 15 NORTH TO LOWER 20S SOUTH LOOK
REASONABLE. FRIDAY...SUNSHINE...LACK OF SNOW COVER...AND RETURN FLOW
SOUTHWEST WINDS WILL ALLOW TEMPERATURES TO RECOVER WELL INTO THE
30S. ..SHEETS..
.LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY...
THE EXTENDED FORECAST REMAINS DOMINATED BY MOSTLY BENIGN NORTHWEST
FLOW FRONTAL PASSAGES. THIS NORMALLY REPRESENTS A BELOW NORMAL
FORECAST FOR TEMPERATURES...BUT WITH SPLIT FLOW...THIS SHOULD KEEP
TEMPERATURES GENERALLY ABOVE NORMAL...AND ALSO WILL KEEP POPS VERY
LOW. THERE REMAINS TWO POTENTIAL POP CHANCES IN THE EXTENDED...BUT
BOTH ARE POORLY SHOWN WITH RESPECT TO CONSISTENCY IN ANY ONE MODEL
RUN. THE FIRST...MONDAY AND MONDAY NIGHT... THE MODEL BLEND KEEPS
THE FORECAST DRY AS THE GFS CONTINUES TO SHOW A CLIPPER PASSING WELL
NORTH OF THE CWA....RESULTING IN DRY WAA DAY. HOWEVER...THE ECMWF
AND CANADIAN BOTH BRING THE CUT OFF LOW FROM THE SOUTHWEST UP OVER
THE CWA MONDAY AND MONDAY NIGHT...RESULTING IN POTENTIAL RAIN OR
SNOW. FOR NOW...HAVE BUMPED UP POPS TO 10 TO 14 PERCENT AND SKY
COVER AS WELL...BUT LEFT DRY.
AFTER SEVERAL MORE DAYS OF BENIGN NORTHWEST FLOW...MODELS SHOW
ANOTHER BROAD TROF MOVING PAST THE REGION AROUND FRIDAY. THIS WAVE
INITIALIZED WITH SLIGHT TO LOW CHANCE POPS FOR SNOW.
TEMPERATURES THROUGHOUT THE FORECAST ARE GENERALLY FROM THE MID 30S
TO MID 40S...WITH LOWS IN THE MID 20S TO LOWER 30S. SUCH
TEMPERATURES ARE VERY MILD FOR THE SHORTEST DAYS OF THE YEAR.
..ERVIN..
&&
.AVIATION...
HIGH PRESSURE BUILDING INTO THE PLAINS WILL CONTINUE TO PUSH
COLDER...DRIER AIR INTO THE AREA LOCAL AREA LATE THIS AFTERNOON INTO
EVENING...DRIVING THE LOW CLOUDS SOUTHWARD. CIGS LIFTED TO VFR EARLY
THIS AFTERNOON AT CID AND DBQ...AND THIS CLEARING TREND IS EXPECTED
REACH MLI AND BRL LATE THIS AFTERNOON INTO EARLY EVENING. A WEAK
UPPER LEVEL DISTURBANCE PRODUCING A BAND OF FLURRIES OVER SE IA AT
MID AFTERNOON MAY AFFECT BRL BEFORE 00Z...AND A TEMPO GROUP FOR MVFR
VSBYS HAS BEEN ADDED IN AN UPDATE. OVERNIGHT INTO FRIDAY...SKIES
WILL BECOME MOSTLY CLEAR WITH NORTH WINDS BACKING TO THE WEST AND
THEN SOUTHWEST BY LATE MORNING. ..SHEETS..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SHEETS/ERVIN
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1110 AM CST THU DEC 22 2011
.AVIATION...
FOR THE 18Z TAF ISSUANCE...
LIGHT SNOW AND BLOWING SNOW WILL KEEP KDDC AND KGCK IN IFR CIGS
AND VSBYS THROUGH 22Z TO BE IFR. KHYS WILL HAVE MVFR CIGS WITH 6SM
PLUS VSBY. NORTHEAST WINDS OF 20 TO 25 KNOTS WILL PERSIST THROUGH
22 TO 23Z. AS THE UPPER AIR DISTURBANCE EXITS EAST THIS EVENING,
THE WINDS WILL DIMINISH TO NORTHWEST AT 10 KTS OR LESS AFTER 03Z,
AND BOTH CIGS AND VSBYS WILL IMPROVE TO VFR BY 03Z. CLEAR SKIES ARE
EXPECTED AFTER 09Z TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 539 AM CST THU DEC 22 2011/
SYNOPSIS...
22.00Z 300 HPA JET ANALYSIS SHOWS THAT KANSAS LIES BETWEEN A STRONG
SOUTHERN JET EXTENDING FROM MEXICO TO THE LOWER MISSISSIPPI RIVER VALLEY
AND A NORTHERN JET WAS SLIDING EAST ACROSS THE NORTHERN PLAINS. A 75-85
KT JET WAS MOVING PUSHING SOUTHWARD UPSTREAM OF A 500 HPA LOW PRESSURE
CENTER LOCATED ACROSS EASTERN UTAH. MID ATMOSPHERE ANALYSIS INDICATES
COLD AIR OF -30 TO -37 DEG C AIR FROM WYOMING NORTHWARD TO/ACROSS THE
CANADIAN PRAIRIES. AT 700 AND 850 HPA...COLDER AIR WAS ADVECTING ACROSS
THE NORTHERN AND CENTRAL PLAINS. AT THE SURFACE, A COLD FRONT WAS PUSHING
ACROSS THE STATE OF KANSAS EARLY THIS MORNING. -SUGDEN
DISCUSSION...
DAYS 1-2...
TODAY:
THE AFOREMENTIONED MID ATMOSPHERIC LOW WILL SINK SOUTHWARD FROM UTAH
TO THE 4 CORNERS REGION. THE 80-90 KT JET WRAPPING AROUND THIS LOW WILL
PUT WESTERN KANSAS JUST NORTH OF THE LEFT EXIT REGION WITH DYNAMIC LIFT
AND 700 OMEGA DEVELOPING ACROSS THE REGION. IN ADDITION, UPSLOPE 700/850
HPA FLOW WILL PROVIDE ENOUGH LOW TO MID LEVEL LIFT TO PROVIDE THE REGION
WITH LIGHT SNOW SHOWERS TODAY. THE LATEST HRRR (WHICH ONLY GOES OUT
TIL ABOUT 20Z) WAS USED AS A STARTING FOUNDATION FOR SNOW ACCUMULATION.
MUCH OF THE REGION WILL SEE ABOUT 0.5 TO 1.0 INCHES WITH SLIGHTLY MORE
POSSIBLE ACROSS MY NORTHWEST COUNTIES (FLIRTING TO AROUND 2.0 INCHES).
HAVE ADDED BLOWING SNOW BASED OFF UPSTREAM OBSERVATIONS SHOWING A REDUCTION
IN VISIBILITIES ALREADY. OTHERWISE, TODAY WILL BE CLOUDY WITH NORTH
TO NORTHEASTERLY WINDS RUNNING AROUND 20 KT IN THE WAKE OF A COLD FRONT.
WILL HIGHLIGHT THE LIGHT SNOW ACCUMULATIONS/BLOWING SNOW IN THE HWO
BUT THIS WILL BE BELOW ADVISORY CRITERIA SO AM NOT PLANNING TO ISSUE
A WSW RIGHT NOW. MAXIMUM TEMPERATURES WILL BE IN THE UPPER 20S TO LOWER
30S DEG F.
TONIGHT:
PRECIPITATION WILL END THIS EVENING FROM THE NORTHEAST TO THE SOUTHWEST
AS THE MID LEVEL LOW SINKS FURTHER SOUTH. FORECAST SOUNDINGS SHOW QUITE
A BIT OF DRYING LATE TONIGHT INTO TOMORROW MORNING SO I HAVE RAMPED
CLOUD COVER DOWN. WITH CLEARING SKIES AND A SURFACE HIGH PRESSURE CENTER
SLIDING ACROSS KANSAS, A GOOD NIGHT FOR RADIATIONAL COOLING IS EXPECTED.
MINIMUM TEMPERATURES IN THE SINGLE DIGITS DEG F IS EXPECTED ACROSS FAR
WESTERN KANSAS. SLIGHTLY WARMER TEMPERATURES WITH TEENS DEG F ARE EXPECTED
ACROSS SOUTH CENTRAL KANSAS.
FRIDAY/FRIDAY NIGHT:
I HAVE INCREASED TEMPERATURES FRIDAY AS A LEE TROUGH DEVELOPS ACROSS
THE LEE OF THE ROCKIES AND MOVES EAST IN ASSOCIATION WITH THE PASSAGE
OF A WEAK SHORTWAVE TROUGH TRAVERSING ACROSS THE NORTHERN PLAINS. MAXIMUM
TEMPERATURES SHOULD WARM TO NEAR TO SLIGHTLY ABOVE FREEZING WITH A BIT
OF DOWNSLOPE SOUTHWESTERLY TO WESTERLY SURFACE WINDS. A DRY ATMOSPHERE
WILL LEAD TO FULL INSOLATION ON FRIDAY AS WELL. A BIT OF EROSION OF
THE SNOW FIELD IS POSSIBLE FRIDAY FOR AREAS THAT GET ABOVE FREEZING.
OVERNIGHT LOWS INTO SATURDAY WILL BE SLIGHTLY WARMER WITH THE CONTINUATION
OF A DOWNSLOPE WESTERLY WIND. NO PRECIPITATION IS EXPECTED FRIDAY. -SUGDEN
DAYS 3-7...
THE PERIOD SATURDAY THROUGH WEDNESDAY WILL BE VERY QUIET SENSIBLE WEATHER
WISE WITH NO PRECIPITATION EXPECTED DURING THIS ENTIRE PERIOD. THE PLANETARY
SCALE PATTERN ACROSS THE NORTH PACIFIC INTO NORTH AMERICA WILL BE CHARACTERIZED
BY A LOW WAVE NUMBER/LOW AMPLITUDE WHICH WILL RESULT IN A WARMER-THAN-
AVERAGE PERIOD OF WEATHER ACROSS THE WESTERN PLAINS...IF IT WERE NOT
FOR A FAIRLY HEALTHY SNOW PACK IN PLACE.
THE 19-20 DECEMBER BLIZZARD CAUSED A LARGE SNOWPACK ACROSS SOUTHEASTERN
COLORADO AND WEST-CENTRAL/SOUTHWEST KANSAS WHICH WILL TAKE SEVERAL DAYS
TO DWINDLE DOWN. AS A RESULT...HIGH TEMPERATURE FORECASTING WILL BE
DIFFICULT...AND WILL BE DEPENDENT UPON THE DAILY REDUCTION OF THE SNOWPACK.
AN UPPER RIDGE WILL BUILD OVER THE ROCKIES SATURDAY/SATURDAY NIGHT...WHICH
WILL THEN ERODE AS ZONAL JET FLOW MOVES INTO THE NORTHERN ROCKIES SPAWNING
A DEEP LEE TROUGH FROM ALBERTA SOUTH TO EASTERN COLORADO. THIS LOOKS
LIKE A CLASSIC DOWNSLOPE WARMING SETUP AND IT WOULD APPEAR ON PAPER
THAT THIS DAY WILL BE QUITE WARM AND WILL REALLY KNOCK OUT A GOOD CHUNK
OF WHATEVER REMNANT SNOWPACK THERE IS ACROSS WESTERN DDC FORECAST AREA.
WITH SOME COLLABORATION HAVE INCREASED THE HIGHS A FEW DEGREES OVER
THE ALLBLEND GUIDANCE FOR MONDAY. THIS IS THE ONLY CHANGE MADE AGAINST
THE ALLBLEND GUIDANCE FOR THE MEDIUM RANGE.
IN THE FAR EXTENDED TIME FRAME...AN EXTENDED NORTH PACIFIC JET WILL
MIGRATE EASTWARD DURING THE 27-30 DECEMBER TIME FRAME WITH A HINT AT
RIDGE BUILDING SOMEWHERE BETWEEN 140W AND 120W...WHICH COULD FAVOR DOWNSTREAM
TROUGH DEVELOPMENT OVER THE WESTERN OR CENTRAL CONUS BY THE 30-31 DECEMBER
TIME FRAME. THIS WOULD BE THE EARLIEST TIME FRAME THAT PRECIPITATION
CHANCES COULD ENTER THE PICTURE...BUT THIS IS IN THE DAY 8-10 TIME FRAME
AND IT REMAINS TO BE SEEN HOW THE SYNOPTIC SCALE EVOLVES AS THE EXTENDED
JET APPROACHES THE NORTHEAST PACIFIC. -UMSCHEID
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 31 14 33 14 / 50 10 0 0
GCK 31 8 33 12 / 60 20 0 0
EHA 29 10 27 16 / 70 20 0 0
LBL 32 12 31 15 / 60 20 0 0
HYS 32 13 34 14 / 60 10 0 0
P28 33 19 36 21 / 50 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 4 PM CST /3 PM MST/ THIS AFTERNOON
FOR KSZ030-031-043>046-061>065-074>078-084>087.
&&
$$
FN12/99/99
AREA FORECAST DISCUSSION
NWS GRAY ME
508 PM EST THU DEC 22 2011
.SYNOPSIS...
A WEAK AREA OF LOW PRESSURE WILL TRACK NORTHEAST FROM THE MID
ATLANTIC STATES TONIGHT THEN CONTINUE TO MOVE TO THE NORTHEAST
JUST BEYOND THE GULF OF MAINE ON FRIDAY. HIGH PRESSURE AND DRY
AIR FOLLOWS FOR LATER SATURDAY INTO CHRISTMAS DAY. A WEAK WARM
FRONT COULD PRODUCE A FEW SNOW SHOWERS ACROSS NORTHERN SECTIONS OF
THE AREA LATE CHRISTMAS DAY. A COLD FRONT WILL CROSS THE AREA
EARLY MONDAY, WHILE AN OCEAN LOW PASSES WELL SOUTH AND EAST OF THE
AREA. HIGH PRESSURE WILL BUILD BY TO OUR SOUTH LATE MONDAY INTO
TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
UPDATE...
MINOR ADJUSTMENTS MADE TO THE TEMPERATURE AND DEW POINT GRIDS
BASED ON CURRENT CONDITIONS. PRECIPITATION SHIELD CONTINUES TO
MOVE STEADILY NORTHEASTWARD AND WILL ARRIVE QUICKLY AROUND OR
SHORTLY AFTER MIDNIGHT. AWAITING FOR BOUNDARY LAYER TEMPERATURES
TO COOL AS WARM GROUND WILL INHIBIT ACCUMULATIONS AT THE ONSET.
PRECIPITATION RATES INCREASE LATER TONIGHT WHICH WILL AID IN
COOLING THE COLUMN. WILL TAKE A GOOD LOOK AT THE 00Z GYX SOUNDING
FOR LOW LEVEL TRENDS IN THE ATMOS.
MINOR ADJUSTMENT MADE TO OTHER PRODUCTS...BUT ALL IN
ALL...FORECAST APPEARS IN GOOD SHAPE. WILL LIKELY BE ISSUING A
STATEMENT LATER THIS EVENING TO ACCOUNT FOR THE TIMING AND PTYPE
TRENDS...SINCE MUCH OF THIS WILL AFFECT THE MORNING RUSH HOUR.
TIMING OF STEADY PCPN: LATEST HRRR RUN BRINGS THE
HEAVIEST/STEADIEST PCPN TO SOUTHERN NEW HAMPSHIRE AROUND 09Z WHICH
SEAMS REASONABLE AT THIS TIME.
PREV DISC...
A WEAK AND FAST MOVING SFC LOW MOVES NE FROM THE MID ATLANTIC
STATES TNGT THEN TRACKS TO THE NE JUST BEYOND THE GULF OF MAINE
FRIDAY...REACHING E OF THE HAGUE LINE LATE IN THE DAY. THE TRACK
IS ABOUT OVER THE BENCHMARK OF 40N 70W BUT DUE TO ITS RAPID
MOVEMENT AMOUNTS SHOULD REMAIN LIGHT. ALSO THE UPR LVL SUPPORT IS
LIMITED WITH A POSITIVE TILTED TROF AND A WEAK SFC LOW AS A
RESULT. STILL...THE MODELS FCST GENERALLY 2-4 INCHES OF SNOW WITH
THE HIGHEST AMOUNTS OVER SOUTHERN AREAS OF INTERIOR MAINE AND NH.
A FEW HIGHER AMOUNTS OF AROUND 5 INCHES CAN`T BE RULED OUT OVER
SOME AREAS OF HIGHER TERRAIN OVER SOUTHERN INTERIOR PORTIONS. THE
MOUNTAINS WILL SEE THE LEAST AMOUNT OF SNOWFALL WITH THIS SYSTEM
WITH ONLY AN INCH OR TWO EXPECTED.
THE TIMING OF THE PCPN IS FOR IT TO BEGIN OVER SOUTHWEST AREAS
AROUND OR SHORTLY AFTER MIDNIGHT BUT THEN RAPIDLY DEVELOP AND
OVERSPREAD THE REST OF THE REGION BY 10Z.
THE PRCP COULD START AS -RA OR MIXED -RASN OVER MORE SERN AND
COASTAL AREAS TNGT AS BOUNDARY LAYER UP TO 925 MB WILL HAVE TEMPS
AROUND OR JUST ABOVE FREEZING. EVENTUALLY PRCP CHANGES TO SN AS
TEMPS COOL DOWN. ON FRIDAY THE SN MAY MIX BACK TO RA IN THE MRNG OVER
THESE AREAS AS SFC AND BOUNDARY LAYER TEMPS AGAIN BEGIN TO CLIMB
INTO THE MID 30S.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
CANADIAN HIGH PRES BUILDS SLOWLY SOUTH SO SOME CLEARING AND DRY CONDITIONS
EXPECTED WITH A RETURN TO MUCH COLDER TEMPS. USED A 50/50 BLEND
OF THE MAV/MET TEMPS.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
QUIET WEATHER FOR THE MOST THROUGH THE PERIOD. PERHAPS A FEW SNOW
SHOWERS XMAS AFTERNOON AND EVENING WITH SHORT WAVE TROUGH. THIS
MAY START AS SOME LIGHT OCEAN ENHANCED SNOW ON THE MID COAST
DURING THE AFTERNOON ON XMAS. OTHERWISE...WE/LL HAVE TO WAIT UNTIL
THE 28TH OR SO FOR THE POSSIBILITY OF ANYTHING DECENT IN THE
PRECIPITATION DEPT...AND EVEN THEN THE MODELS HAVE BEEN
INCONSISTENT.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
SHORT TERM...VFR CONDS THIS EVENING WILL BECOME MVFR TO IFR AFTER
MIDNIGHT FROM SOUTH TO NORTH AS SNOW DEVELOPS AND SPREADS NORTH.
OVER SOUTHEAST NEW HAMPSHIRE THE PCPN MAY FALL AS A MIX AT TIMES.
CONDITIONS WILL GRADUALLY IMPROVE TO VFR FRIDAY AFTERNOON ALTHOUGH
SOME SCATTERED SNOW SHOWERS MAY BRIEFLY REDUCE CIGS/VSBYS TO MVFR.
VFR CONDS ACROSS ALL AREAS FRIDAY NIGHT.
LONG TERM...MAINLY VFR THROUGH TUESDAY. A PERIOD OF MVFR POSSIBLE
XMAS DAY AND NIGHT IN SNOW SHOWERS.
&&
.MARINE...
SHORT TERM...WINDS AND SEAS WILL REMAIN BELOW SCA LEVELS
TNGT AND FRIDAY AS A WEAK AND FAST MOVING COASTAL LOW PASSES SOUTH
OF NEW ENGLAND. CANADIAN HIGH PRESSURE TO OUR NORTH SLOWLY BUILDS
SOUTH ACROSS THE WATERS FRIDAY NIGHT.
LONG TERM...SCA CONDS POSSIBLE OVER THE WEEKEND.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1143 AM CST THU DEC 22 2011
.AVIATION...
CLOUDS CONTINUE TO MOVE SOUTH WITH GENERALLY CLEAR SKIES EXPECTED
INTO TOMORROW. COULD SEE SOME PASSING THIN HIGH CLOUDS BUT WITH
HIGH PRESSURE DOMINATING THE REGION EXPECTED VFR CONDITIONS AND
LIGHT WINDS...LESS THAN 10KTS...THROUGH TOMORROW MORNING.
&&
.PREV DISCUSSION.../ISSUED 358 AM CST THU DEC 22 2011/
DISCUSSION...
NEAR TERM MODEL SOLUTIONS CONTINUE TO INDICATE AN ABRUPT END TO
THE SNOWFALL AS DRIER AIR AND DIMINISHING FORCING WILL
EFFECTIVELY END SNOW PRODUCTION BEFORE SUNRISE FOR MOST OF THE
FORECAST AREA. THE LONE EXCEPTIONS WILL BE THE FAR SOUTHERN
COUNTIES...WHERE MODEL CONSENSUS WOULD SUGGEST -SN OR FLURRIES UP
THROUGH 15Z TODAY. FLURRIES ALSO MAY BE POSSIBLE ACROSS THE SAND
HILLS THROUGH MID MORNING AS THE 22.05Z HRRR INDICATES CSI
BANDING IN THE WAKE OF THE DEPARTING SYSTEM. CROSS SECTIONS DO
REVEAL A SHORT PERIOD WHERE MOMENTUM LINES RUN PARALLEL TO THE
THETA SURFACES...SO WILL NOT RULE OUT A STRAY FLURRY OR SNOW
SHOWER...BUT GIVEN RECENT RADAR TRENDS AND THE DRYING...FEEL THAT
THE THREAT WILL BE MINIMAL AT BEST. OTHERWISE...CAA AND SNOW
PACK...ALBEIT SLIGHT SNOW PACK...WITH HELP KEEP TEMPERATURES
BELOW AVERAGE THIS AFTERNOON...WITH GENERAL MODEL CONSENSUS
SUGGESTING HIGHS IN THE LOWER 30S. DID UNDERCUT GUIDANCE SLIGHTLY
ACROSS THE WEST...WHERE A SLIGHTLY DEEPER SNOW PACK RESIDES...MID
TO UPPER 20S SHOULD BE FINE. FOR TONIGHT..WESTERLY DOWN SLOPING
FLOW DEVELOPS OVERNIGHT AS CANADIAN HIGH PRESSURE SETTLES ACROSS
THE DEEPER SNOW PACK OF EASTERN COLORADO AND WESTERN
KANSAS/OKLAHOMA. GUIDANCE IS SUGGESTING RATHER COLD TEMPERATURES
ACROSS THE CWA...WITH POSSIBLY SUB ZERO READINGS ACROSS THE FAR
WESTERN ZONES. NOT READY TO LOWER MINS THAT MUCH...ESPECIALLY
SINCE WEAK WAA AND DOWN SLOPE FLOW SHOULD PREVAIL. AS OF
NOW...SINGLE DIGIT LOWS LOOK APPROPRIATE ACROSS THE WESTERN HALF
OF THE CWA...WITH LOW TO MID TEENS ACROSS THE EAST. ON
FRIDAY...RISING HEIGHTS ASSOCIATED WITH SHORTWAVE RIDGING WILL
WORK IN CONCERT WITH DOWN SLOPING FLOW TO PUSH TEMPERATURES UP TO
NEAR CLIMO...WITH HIGHS BACK INTO THE UPPER 30S...POSSIBLY IN THE
LOW 40S FOR THE WARM BIASED LOCATIONS.
FOR THE HOLIDAY WEEKEND AND BEYOND. NORTHWESTERLY FLOW WILL
BECOME ESTABLISHED ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS AS
RIDGING BUILDS ACROSS THE WESTERN CONUS. THE NORTHERN STREAM
REMAINS ACTIVE...WITH INDICATIONS OF SEVERAL SHORTWAVES PUSHING
SOUTHEAST FROM THE CANADIAN ROCKIES TOWARD THE GREAT LAKES
REGION...BUT A LACK OF KINEMATIC FORCING WILL KEEP PRECIPITATION
OUT OF THE FORECAST THROUGH MIDWEEK. AS FOR TEMPERATURES...A
GRADUAL WARMING TREND IS EXPECTED THROUGH EARLY NEXT WEEK. HIGHS
SATURDAY AND CHRISTMAS DAY SHOULD CLIMB ABOVE 40F AS INCREASING
THICKNESS BUILDS OVER WESTERN NEBRASKA. MONDAY APPEARS TO BE THE
WARMEST DAY YET...AS H85 TEMPS FLIRT WITH 10C AND DOWN SLOPING
FLOW HELP WARM TEMPS AOA 50F. LOWS THROUGH THE EXTENDED LOOK TO
REMAIN ABOVE SEASONAL NORMS...WITH MID TEENS AND 20S EXPECTED.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AVIATION...MASEK
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1128 AM CST THU DEC 22 2011
.DISCUSSION...
UPDATED THE FORECAST FOR TEMPERATURE AND SKY TRENDS. PATCH OF
STRATUS IS IN PLACE BEHIND THE MAIN SYSTEM CLEARING LINE. RUC HAS
A DECENT HANDLE ON THE CLOUDS WITH THE 900MB RH FIELD...AND IT
INDICATES THAT THE STRATUS WILL LINGER THROUGH AROUND 00-03Z. HAVE
INCREASED CLOUDS IN THE NORTHWEST CWA THROUGH THE DAY. HAVE
LOWERED TEMPS IN THE NORTH/NORTHWEST CWA AS WELL...AS TEMPS ARE
STILL HOVERING AROUND 20 AND CLOUDS WILL COMBINE WITH COLD AIR
ADVECTION TO STUNT TEMPERATURE RISE.
MAYES
&&
.AVIATION...
18Z TAFS FOR KOMA...KLNK...AND KOFK.
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF CYCLE AT KOMA AND
KLNK. AT KOFK...MVFR STRATUS DECK IS PERSISTING...AND WILL THROUGH
MUCH OF THE AFTERNOON...BEFORE BREAKING TO VFR CONDITIONS FOR THE
REST OF THE TAF CYCLE. NORTH WINDS WILL DIMINISH THROUGH THIS
AFTERNOON...WITH LIGHT WINDS OVERNIGHT SWITCHING FROM NORTHWEST TO
SOUTHWEST BEFORE WINDS INCREASE OUT OF THE SOUTHWEST DURING THE
LATE MORNING.
MAYES
&&
.PREV DISCUSSION... /ISSUED 327 AM CST THU DEC 22 2011/
DISCUSSION...TODAY THROUGH TUESDAY.
NARROW BAND OF LIGHT SNOW FROM GREAT LAKES REGION TO ERN KS THIS
MORNING LINING UP WELL ALONG AXIS OF 700-500MB AGEOSTROPHIC
FORCING. THE SNOW ACTIVITY WAS TRACKING SLOWLY TO THE SOUTHEAST AND
WILL CONTINUE TO DO SO WITH THE AID OF SHORTWAVE ENERGY DROPPING
OUT OF CANADA INTO THE UPPER MIDWEST. OTHERWISE DRY CONDITIONS ON
TAP THRU THE WEEKEND AND EARLY PART OF NEXT WEEK. MODELS ARE IN
GREAT AGREEMENT THE CENTRAL PLAINS WILL UNDERGO A GRADUAL WARMING
TREND IN RESPONSE TO UPPER LEVEL POSITIVE TILT LONGWAVE TROF OVER THE
WRN/CNTRL CONUS GETTING KICKED EAST AND INCREASING THICKNESSES
BUILDING IN. THIS LEADING TO MAX TEMPS GOING FROM AROUND 30
TODAY TO THE MID 40S BY MONDAY AND TUESDAY.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1136 AM CST THU DEC 22 2011
.SHORT TERM...TODAY THROUGH SATURDAY NIGHT
305 AM CST THU DEC 22 2011
MAIN CONCERNS WILL BE LINGERING SNOW ACROSS SOUTHERN WI INTO
NORTHEAST IA EARLY THIS MORNING...THEN SLIGHT SNOW CHANCES ACROSS
NORTHERN WISCONSIN ON FRIDAY.
RADAR AND SURFACE OBSERVATIONS SHOWING A BAND OF LIGHT SNOW
EXTENDING FROM EAST CENTRAL WISCONSIN...THROUGH SOUTHWEST WI AND
CENTRAL IA. AT THE NWS OFFICE HERE AROUND A HALF INCH HAS FALLEN SO
FAR. SHORTWAVE TROUGH PRODUCING LIFT FOR THIS SNOW WAS INDICATED ON
WATER VAPOR IMAGERY ACROSS SD/NEB. AIDING IN THE BANDING OF THIS
SNOW WAS CONFLUENT 850-700MB FLOW/WEAK FRONTOGENESIS INDICATED BY
THE RUC MODEL FROM NORTHEAST IA INTO SOUTHERN WI. LOWEST VISIBILITY
UNDER THE HIGHEST REFLECTIVITY BAND ON RADAR AROUND 1SM AT BOSCOBEL
AND MINERAL POINT WI. OTHERWISE...UNDER MOSTLY CLOUDY SKIES ACROSS
THE FORECAST AREA...TEMPERATURES AT 3 AM RANGED FROM THE MID 20S
ACROSS NORTH CENTRAL WI TO THE LOWER 30S SOUTH OF I-90.
22.00Z NCEP MODEL SUITE/29.03Z SREF IN GOOD AGREEMENT THROUGH THE
SHORT TERM.
FOR TODAY...MAIN CONFLUENT 850-700MB FLOW/FRONTOGENESIS SHIFTS
SOUTHEAST OF THE AREA BY 9 AM...BRINGING AN END TO SNOW CHANCES FOR
THE AREA. OTHERWISE...IR IMAGERY SHOWS A DECENT FIELD OF
STRATOCUMULUS ACROSS MN INTO WI...AND THIS WILL LIKELY HOLD THROUGH
MUCH OF THE MORNING...THEN START TO SCOUR OUT THROUGH THE AFTERNOON
HOURS AS A RIDGE OF HIGH PRESSURE/INCREASING SUBSIDENCE BUILDS IN
FROM THE PLAINS.
NORTHWEST FLOW ALOFT WILL BRING A FAIRLY VIGOROUS MID-LEVEL
SHORTWAVE TROUGH AND SURFACE LOW ACROSS SOUTHERN ONTARIO/LAKE
SUPERIOR REGION ON FRIDAY. NAM/GFS SHOW BEST FORCING AND CHANCES FOR
SNOW WILL BE CONFINED CLOSE TO THE TROUGH/LOW. HOWEVER...THE 29.00Z
ECMWF/GEM SHOW LIGHT QPF ALL THE WAY DOWN TO I-94. WENT WITH A
COMPROMISE AND KEPT A SMALL/SLIGHT CHANCE POP IN FOR TAYLOR COUNTY.
THE FORECAST AREA WILL THEN BE IN THE WARM SECTOR OF A LOW PRESSURE
SYSTEM PASSING THROUGH CANADA ON SATURDAY. SOUTHWEST SURFACE FLOW
AND AMPLE SUNSHINE SHOULD WARM HIGHS WELL INTO THE 30S WITH PERHAPS
A FEW READINGS AROUND THE 40 DEGREE MARK ACROSS FAR SOUTHWEST
WI/NORTHEAST IA.
.LONG TERM...CHRISTMAS DAY THROUGH WEDNESDAY
305 AM CST THU DEC 22 2011
22.00Z GFS/ECMWF IN DECENT AGREEMENT THROUGH THE LONG TERM.
A COLD FRONT WILL DROP SOUTH ACROSS THE AREA CHRISTMAS DAY...BUT
APPEARS THE BULK OF THE COLD AIR ADVECTION WILL BE ALONG/NORTHEAST
OF I-94. AS A RESULT...COULD SEE HIGHS AROUND THE 40 DEGREE MARK
AGAIN SOUTHWEST OF I-94...ESPECIALLY FROM FAR SOUTHWEST WI INTO
NORTHEAST IA. OTHERWISE...WILL PROBABLY SEE SOME BLUSTERY CONDITIONS
WITH GOOD MIXING/FAIRLY TIGHT PRESSURE GRADIENT.
FAIRLY ACTIVE ZONAL FLOW REMAINS IN PLACE WITH STORM SYSTEMS STAYING
MAINLY NORTH OF THE U.S./CANADIAN BORDER. THIS KEEPS PRECIPITATION
CHANCES NORTH OF THE AREA AND WILL CONTINUE TO PRODUCE ABOVE NORMAL
TEMPERATURES.
&&
.AVIATION...THROUGH 18Z FRIDAY
1136 AM CST THU DEC 22 2011
THE MAIN FOCUS OF THE TAFS IS WITH THE TIMING OF WHEN THE 2KFT TO
4KFT STRATUS CLEARS THE TAF SITES. THIS STRATUS CURRENTLY EXTENDS
ACROSS MUCH OF WISCONSIN AND A SMALL PORTION OF SOUTHEAST
MINNESOTA AND IS SLOWLY DROPPING TO THE SOUTH. CURRENT INDICATIONS
ARE THAT THE BACK EDGE OF THIS STRATUS WILL GET INTO LSE AROUND
21Z AND RST AROUND 22Z. AFTER THESE CLOUDS SHIFT TO THE SOUTHEAST
A RIDGE AXIS OF HIGH PRESSURE WILL SWING THROUGH THE REGION
TONIGHT AND BRING LIGHT AND VARIABLE WINDS ALONG WITH IT. SOME SCT
TO BKN MID LEVEL CLOUDS WILL SKIRT THE TAF SITES OVERNIGHT AS
WELL. WINDS WILL THEN SHIFT TO THE SOUTHWEST TOMORROW MORNING AND
BECOME GUSTY BY LATE MORNING WITH SOME GUSTS UP ABOVE 20KT
POSSIBLE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
305 AM CST THU DEC 22 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM... DAS
LONG TERM.... DAS
AVIATION...HALBACH