Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 12/08/11
AREA FORECAST DISCUSSION
NWS ALBANY NY
942 PM EST WED DEC 7 2011
.SYNOPSIS...
A STORM SYSTEM WILL LIFT NORTHEAST FROM THE DELMARVA REGION THIS
EVENING...TO THE EAST END OF LONG ISLAND AROUND MIDNIGHT...AND
THEN INTO THE GULF OF MAINE THURSDAY MORNING. THIS STORM TRACK
WILL RESULT IN RAIN CHANGING TO SNOW THIS EVENING ACROSS MUCH OF
THE REGION WITH SIGNIFICANT SNOWFALL ACCUMULATIONS OVERNIGHT IN
MANY AREAS. THE HEAVIEST SNOW IS EXPECTED TO FALL ACROSS THE
NORTHERN TACONICS...EASTERN CATSKILLS...BERKSHIRES AND SOUTHERN
GREEN MOUNTAINS. HEAVY RAIN WILL CONTINUE TO FALL OVERNIGHT ACROSS
THE MID HUDSON VALLEY AND LITCHFIELD HILLS.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 930PM RADAR FSI CROSS SECTIONS AND SPOTTER REPORTS HAVE RAIN
CHANGING TO SNOW AROUND THE GREATER CAPITAL DISTRICT. THIS IS
RUNNING AN HOUR OR TWO BEHIND GRIDS AND MADE MINOR CHANGES. THIS
PROCESS WILL RAPIDLY CHANGE RAIN OVER TO SNOW IN NEXT 1-2 HOURS.
00UTC NAM IN LINE WITH PVS QPF AND THINKING. NO DEPARTURES THERE.
ONCE PCPN CHANGES OVER BURST OF SNOW FOR SEVERAL HOURS IN MASSIVE
TILTED FRONTOGENESIS AS MESOSCALE BAND HAS SET UP FM SW VT TO
CATSKILLS (CSTAR) WHILE PCPN MAY BE CHANGING OVER 1-2 HOURS
LATER...DONT THINK IT WILL SIGNIFICANTLY ALTER CURRENT THINKING ON
AMOUNTS OR HEADLINES GIVEN CHARACTER AND FORCING OF THE SNOW
OVERNIGHT.
ALL 3 HOUR PRESSURE MAX FALLS ARE NOW OFFSHORE NJ/DELMARVA. RAPID
DEEPENING WILL OCCUR NEXT FEW HOURS AS 500HPA SHORT WAVE INTERACT
WITH STRONG BAROCLINIC ZONE ALONG COAST.
AS OF 7PM...NOT MAKING ANY CHANGES ATTM. AWAITING CHANGE OVER TO
SNOW. ON ALB 00UTC ALB SOUNDING +4C WARM NOSE REMAINS AT 3500 MSL.
FSI CROSS SECTIONS CAPPI INDICATE BRIGHT BAND LOWERING TO GROUND IN
MONTGOMERY/SCHOHARIE COUNTIES...BUT ONLY ONE REPORT OF SNOW IN
WEST SCHOHARIE COUNTY AN HOUR AGO.
BANDLETS (CSTAR III) HAVE SET UP ACROSS RGN WITH SOME ALONG BRIGHT
BAND AXISES AND OTHERS IN RN TO +RN AREAS. 18UTC NAM/GFS SHOW ALL
THE RIGHT FEATURES FOR FORMATION OF A MAJOR BAND OVER FCA. 20UVM
IN MAX DENDRITIC GROWN ZONE BY 03UTC...STRONG TILTED FRONTOGENESIS
AND EPV. SO THE STAGE IS SET...JUST AWAITING THE ARRIVAL OF THE
COLDER AIR OR ITS DYNAMIC CREATION.
SFC PRES FALLS HAVE SHIFTED TO NJ-DELMARVA COAST BUT 3HR VALUES
REMAIN REMAIN ON ORDER OF 4-6MB. WX WATCH CONTINUES.
WINTER STORM WARNINGS ARE IN EFFECT FOR TONIGHT FOR THE EASTERN
CATSKILLS...NORTHERN TACONICS...BERKSHIRES AND SOUTHERN GREEN
MOUNTAINS AND WINTER WEATHER ADVISORIES IN EFFECT FOR THE
SOUTHEAST ADIRONDACKS...LAKE GEORGE SARATOGA REGION...EASTERN
MOHAWK VALLEY...SACANDAGA REGION...GREATER CAPITAL DISTRICT AND
CENTRAL TACONICS. A FLOOD WATCH IS IN EFFECT THROUGH THURSDAY
MORNING FOR THE MID HUDSON VALLEY...SOUTHERN TACONICS AND
LITCHFIELD HILLS.
SNOWFALL ACCUMULATIONS ARE GENERALLY EXPECTED TO BE 3 TO 8 INCHES
IN THE ADVISORY AREA AND 5 TO 12 INCHES IN THE WARNING AREA EXCEPT
ACROSS THE CENTRAL AND SOUTHEAST CATSKILLS...NORTHERN BERKSHIRES
AND HIGHER TERRAIN OF THE SOUTHERN GREEN MOUNTAINS WHERE 8 TO 16
INCHES OF SNOW IS EXPECTED. TOTAL RAINFALL AMOUNTS IN THE FLOOD
WATCH AREA ARE EXPECTED TO BE IN THE 1.75 TO 2.25 INCH RANGE.
AS OF 530 PM EST...CLOUD TOPS CONTINUE TO COOL ACROSS THE FA WITH
21Z KALB SOUNDING INDICATING A WARM TONGUE OF 4C AT AROUND 875 MB
WITH THE FREEZING LEVEL AT AROUND 775 MB OR 6.6 KFT. HAVE RECEIVED
A REPORT OF 1 INCH OF SNOW THUS FAR IN CHARLOTTEVILLE IN SCHOHARIE
COUNTY WITH HEAVY WET SNOW AND A TEMP OF 36 DEGREES AT AN
ELEVATION OF AROUND 1500 FEET. EXPECT A RAPID CHANGEOVER TO SNOW
THIS EVENING ACROSS MUCH OF THE FA MAINLY BETWEEN 00Z AND 03Z WITH
VERY HEAVY SNOW EXPECTED TO FALL DURING MUCH OF THE NIGHT BEFORE
TAPERING OFF LATE. THE ONLY AREAS WHICH ARE NOT EXPECTED TO
RECEIVE MUCH SNOW ARE FAR NORTHWEST PORTIONS OF THE FA INCLUDING
THE WESTERN ADIRONDACKS AND WESTERN MOHAWK VALLEY WHERE VERY
LITTLE QPF EXPECTED...NORTHERN FRINGE OF PCPN SHIELD AND FAR
SOUTHEAST PORTION OF FA WHICH WILL REMAIN TOO WARM FOR MUCH IN THE
WAY OF SNOW MAINLY FROM THE MID HUDSON VALLEY EAST TO THE
LITCHFIELD HILLS WHERE A FLOOD WATCH IS IN EFFECT.
MANY FAVORABLE FACTORS FOR HEAVY SNOW ARE IN PLACE ACROSS MUCH OF
THE FA WITH THE MOST SIGNIFICANT FACTORS BEING IMPRESSIVE
FRONTOGENESIS H8-H7 EXTENDING FROM THE CATSKILLS NORTHEAST TO
SOUTHERN VERMONT AT 00Z AND THEN SHIFTING TO AN ORIENTATION FROM
JUST EAST OF THE CAPITAL DISTRICT THROUGH THROUGH THE NORTHERN
BERKSHIRES INTO SOUTHERN VERMONT AT 06Z. AS THE EVENING WEARS ON
THE SNOW GROWTH REGION BECOMES INCREASINGLY MORE FAVORABLE WITH
THE -12 TO -18 C TEMP SLICING THROUGH A REGION OF +20 UBAR/SEC. IN
ADDITION IMPRESSIVE EPV EXISTS IN LOWER LEVELS ESPECIALLY BTWN 00Z
AND 06Z. THE LATEST HRRR COL MAX REFLECTIVITY ALSO INDICATES
IMPRESSIVE BANDED PCPN ESPECIALLY ACROSS THE HIGHER TERRAIN IN THE
WARNING AREA BETWEEN 03Z AND 06Z WITH THE BACK EDGE OF THE PCPN
SHIELD EXITING THE FA FROM WEST TO EAST BETWEEN 08Z AND 10Z.
EXPECT LOW TEMPS TONIGHT TO RANGE FROM THE MID 20S NORTHWEST TO
MID 30S FAR SOUTHEAST.
ON THURSDAY EXPECT IMPROVING CONDITIONS WITH HIGH PRESSURE MOVING
IN AND MAINLY DRY CONDITIONS WITH HIGHS RANGING FROM THE UPPER
20S TO LOWER 30S NORTHWEST TO LOWER 40S FAR SOUTHEAST.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
THU NT...BACKING LOW LEVEL WINDS SHOULD ALLOW ANY LINGERING SNOW
BANDS/SNOW SHOWERS TO SHIFT NORTHWARD INTO THE WESTERN
ADIRONDACKS...WITH ADDITIONAL ACCUMS POSSIBLE BEFORE INVERSION
HEIGHTS LOWER AND DIMINISH INTENSITY OF ANY SNOWBANDS.
ELSEWHERE...INITIALLY CLEAR TO PARTLY CLOUDY SKIES SHOULD BECOME
MOSTLY CLOUDY LATER AT NIGHT AS MID LEVEL ISENTROPIC LIFT INCREASES
AHEAD OF NEXT APPROACHING SHORTWAVE. EXPECT MINS TO FALL INTO THE
TEENS AND 20S...WARMEST ACROSS VALLEY REGIONS.
FRI-SAT...UPPER LEVEL TROUGH WILL APPROACH FROM THE W...AND PASS
ACROSS FRI NT. A SFC COLD FRONT ASSOCIATED WITH THIS FEATURE WILL
CROSS THE REGION LATE FRI OR FRI EVE...PRECEDED AND ACCOMPANIED BY
SNOW SHOWERS. THEN...BEHIND THE FRONT...BANDS OF SNOW SHOWERS AND
POSSIBLE SNOW SQUALLS WILL BE POSSIBLE...INITIALLY FAVORING PORTIONS
OF THE WESTERN MOHAWK VALLEY/SCHOHARIE VALLEY...THEN GRADUALLY
SHIFTING NORTHWARD INTO THE WESTERN ADIRONDACKS BY SAT. THERE IS
SOME POTENTIAL FOR LOCALLY HEAVY SNOWFALL AMTS WITHIN SOME OF THESE
BANDS...AND WILL MENTION THIS POSSIBILITY IN THE HWO...WITH GREATEST
THREAT ACROSS THE WESTERN ADIRONDACKS. EXPECT FRI MAXES TO REACH THE
30S IN MOST AREAS...EXCEPT AROUND OR INTO THE LOWER 40S WITHIN THE
VALLEYS...WITH 20S ACROSS HIGHER ELEVATIONS. COLDER AIR BEHIND THE
FRONT WILL MOVE IN FOR FRI NT AND SAT...WITH FRI NT MINS IN THE
TEENS AND LOWER 20S...AND SAT MAXES MAINLY IN THE 30S WITHIN
VALLEYS...AND 20S ACROSS HIGHER ELEVATIONS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THIS PERIOD WILL BE FAIRLY QUIET AS HIGH PRESSURE BUILDS INTO THE
MID ATLANTIC REGION SATURDAY NIGHT AND DOMINATES OUR WEATHER INTO
THE EARLY PART OF THE COMING WEEK. A CHANCE OF SOME LAKE ENHANCED
SNOW SHOWERS SATURDAY NIGHT...THEN DRY UNTIL TUESDAY NIGHT WHEN A
WEAK BOUNDARY BRINGS ABOUT SOME SNOW AND RAIN SHOWERS WEST OF THE
HUDSON VALLEY WEDNESDAY.
THE PERIOD STARTS OFF CHILLY...LOWS FROM AROUND 10 TO 20 ABOVE ON
SUNDAY MORNING...WITH HIGHS SUNDAY ONLY IN THE UPPER 20S TO THE
MID 30S. TEMPERATURES WILL GRADUALLY MODERATE WITH HIGHS RISING
TO THE UPPER 30S AND LOWER 40S BY TUESDAY AFTERNOON.
FOR THE MOST PART...USED HPC GUIDANCE TO POPULATE THE GRIDS.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
WIDESPREAD IFR CONDITIONS ARE EXPECTED THROUGH AT LEAST
08Z/THU...WITH PERHAPS JUST SOME BRIEF IMPROVEMENTS TO MVFR VSBYS AT
TIMES.
RAIN AND DRIZZLE WILL CONTINUE INTO THIS EVENING...WITH SOME PERIODS
OF MODERATE TO HEAVY RAIN POSSIBLE. THEN...A TRANSITION TO WET SNOW
IS TO OCCUR LATER THIS EVENING...ROUGHLY BETWEEN 01Z-03Z/THU AT KGFL
AND KALB...AND NOT UNTIL AFTER 06Z/THU AT KPOU. THE SNOW MAY BE
MODERATE TO HVY IN INTENSITY...ESP AT KALB AND POSSIBLY KPOU.
PRECIPITATION SHOULD DECREASE IN INTENSITY FROM W TO E BETWEEN
07Z-09Z/THU...AND ENDING BY 11Z/THU IN ALL AREAS.
FOR THU...EXPECT MAINLY VFR CONDITIONS...EXCEPT POSSIBLY SOME MVFR
CIGS/VSBY IN ISOLATED SNOW SHOWERS AT KGFL AND KALB LATER IN THE
AFTERNOON.
WINDS WILL REMAIN FROM THE NORTH TO NORTHEAST AT 5-10 KT THIS
AFTERNOON AND EARLY EVENING...THEN SHIFT INTO THE N...THEN NW AND
INCREASE TO 10-20 KT AFTER 05Z/THU. WINDS WILL THEN BACK INTO THE NW
TO W...AND INCREASE TO 15-25 KT AFTER 14Z/THU...WITH SOME GUSTS
POSSIBLY REACHING 30-35 KT AT KALB.
OUTLOOK...
THU NT-SAT...MAINLY VFR...SLIGHT CHC -SHSN. BREEZY.
SUN-MON...VFR...NO SIG WX.
&&
.HYDROLOGY...
A SIGNIFICANT MIXED PRECIPITATION EVENT WAS OCCURRING ACROSS THE
REGION WITH STORM TOTAL LIQUID AMOUNTS FROM LESS THAN A QUARTER
INCH IN NORTHERN HERKIMER COUNTY TO A LITTLE OVER TWO INCHES IN
THE LOWER HUDSON VALLEY OF NEW YORK AND THE LITCHFIELD HILLS OF
CONNECTICUT. OVER COOLER REGIONS SUCH AS THE HIGHER ELEVATIONS OF
THE CATSKILLS...BERKSHIRES...AND GREEN MOUNTAINS OF SOUTHERN
VERMONT A SUBSTANTIAL AMOUNT OF THIS PRECIPITATION IS FORECAST
TO COME AS SNOW. ACROSS OUR SOUTHERNMOST COUNTIES...EASTERN ULSTER
DUTCHESS...AND LITCHFIELD...MOST OF THE PRECIPITATION WILL
COME AS RAIN AND LOCALLY HEAVY AMOUNTS MAY AMOUNT TO ENOUGH TO
RESULT IN SOME MINOR FLOODING OF ROADS AND PARKING AREAS AND
CAUSE RISES OF SEVERAL FEET ON RIVERS AND STREAMS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...FLOOD WATCH UNTIL 9 AM EST THURSDAY FOR CTZ001-013.
NY...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR NYZ047-051-
054-058-063.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR NYZ039>043-
048>050-052-053-059>061-082>084.
FLOOD WATCH UNTIL 9 AM EST THURSDAY FOR NYZ064>066.
MA...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR MAZ001-025.
VT...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR VTZ013-014.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR VTZ015.
&&
$$
SYNOPSIS...11
NEAR TERM...11/SNYDER
SHORT TERM...KL
LONG TERM...RCK
AVIATION...RCK
HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS ALBANY NY
703 PM EST WED DEC 7 2011
.SYNOPSIS...
A STORM SYSTEM WILL LIFT NORTHEAST FROM THE DELMARVA REGION THIS
EVENING...TO THE EAST END OF LONG ISLAND AROUND MIDNIGHT...AND
THEN INTO THE GULF OF MAINE THURSDAY MORNING. THIS STORM TRACK
WILL RESULT IN RAIN CHANGING TO SNOW THIS EVENING ACROSS MUCH OF
THE REGION WITH SIGNIFICANT SNOWFALL ACCUMULATIONS OVERNIGHT IN
MANY AREAS. THE HEAVIEST SNOW IS EXPECTED TO FALL ACROSS THE
NORTHERN TACONICS...EASTERN CATSKILLS...BERKSHIRES AND SOUTHERN
GREEN MOUNTAINS. HEAVY RAIN WILL CONTINUE TO FALL OVERNIGHT ACROSS
THE MID HUDSON VALLEY AND LITCHFIELD HILLS.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 7PM...NOT MAKING ANY CHANGES ATTM. AWAITING CHANGE OVER TO
SNOW. ON ALB 00UTC ALB SOUNDING +4C WARM NOSE REMAINS AT 3500 MSL.
FSI CROSS SECTIONS CAPPI INDICATE BRIGHT BAND LOWERING TO GROUND IN
MONTGOMERY/SCHOHARIE COUNTIES...BUT ONLY ONE REPORT OF SNOW IN
WEST SCHOHARIE COUNTY AN HOUR AGO.
BANDLETS (CSTAR III) HAVE SET UP ACROSS RGN WITH SOME ALONG BRIGHT
BAND AXISES AND OTHERS IN RN TO +RN AREAS. 18UTC NAM/GFS SHOW ALL
THE RIGHT FEATURES FOR FORMATION OF A MAJOR BAND OVER FCA. 20UVM
IN MAX DENDRITIC GROWN ZONE BY 03UTC...STRONG TILTED FRONTOGENESIS
AND EPV. SO THE STAGE IS SET...JUST AWAITING THE ARRIVAL OF THE
COLDER AIR OR ITS DYNAMIC CREATION.
SFC PRES FALLS HAVE SHIFTED TO NJ-DELMARVA COAST BUT 3HR VALUES
REMAIN REMAIN ON ORDER OF 4-6MB. WX WATCH CONTINUES.
WINTER STORM WARNINGS ARE IN EFFECT FOR TONIGHT FOR THE EASTERN
CATSKILLS...NORTHERN TACONICS...BERKSHIRES AND SOUTHERN GREEN
MOUNTAINS AND WINTER WEATHER ADVISORIES IN EFFECT FOR THE
SOUTHEAST ADIRONDACKS...LAKE GEORGE SARATOGA REGION...EASTERN
MOHAWK VALLEY...SACANDAGA REGION...GREATER CAPITAL DISTRICT AND
CENTRAL TACONICS. A FLOOD WATCH IS IN EFFECT THROUGH THURSDAY
MORNING FOR THE MID HUDSON VALLEY...SOUTHERN TACONICS AND
LITCHFIELD HILLS.
SNOWFALL ACCUMULATIONS ARE GENERALLY EXPECTED TO BE 3 TO 8 INCHES
IN THE ADVISORY AREA AND 5 TO 12 INCHES IN THE WARNING AREA EXCEPT
ACROSS THE CENTRAL AND SOUTHEAST CATSKILLS...NORTHERN BERKSHIRES
AND HIGHER TERRAIN OF THE SOUTHERN GREEN MOUNTAINS WHERE 8 TO 16
INCHES OF SNOW IS EXPECTED. TOTAL RAINFALL AMOUNTS IN THE FLOOD
WATCH AREA ARE EXPECTED TO BE IN THE 1.75 TO 2.25 INCH RANGE.
AS OF 530 PM EST...CLOUD TOPS CONTINUE TO COOL ACROSS THE FA WITH
21Z KALB SOUNDING INDICATING A WARM TONGUE OF 4C AT AROUND 875 MB
WITH THE FREEZING LEVEL AT AROUND 775 MB OR 6.6 KFT. HAVE RECEIVED
A REPORT OF 1 INCH OF SNOW THUS FAR IN CHARLOTTEVILLE IN SCHOHARIE
COUNTY WITH HEAVY WET SNOW AND A TEMP OF 36 DEGREES AT AN
ELEVATION OF AROUND 1500 FEET. EXPECT A RAPID CHANGEOVER TO SNOW
THIS EVENING ACROSS MUCH OF THE FA MAINLY BETWEEN 00Z AND 03Z WITH
VERY HEAVY SNOW EXPECTED TO FALL DURING MUCH OF THE NIGHT BEFORE
TAPERING OFF LATE. THE ONLY AREAS WHICH ARE NOT EXPECTED TO
RECEIVE MUCH SNOW ARE FAR NORTHWEST PORTIONS OF THE FA INCLUDING
THE WESTERN ADIRONDACKS AND WESTERN MOHAWK VALLEY WHERE VERY
LITTLE QPF EXPECTED...NORTHERN FRINGE OF PCPN SHIELD AND FAR
SOUTHEAST PORTION OF FA WHICH WILL REMAIN TOO WARM FOR MUCH IN THE
WAY OF SNOW MAINLY FROM THE MID HUDSON VALLEY EAST TO THE
LITCHFIELD HILLS WHERE A FLOOD WATCH IS IN EFFECT.
MANY FAVORABLE FACTORS FOR HEAVY SNOW ARE IN PLACE ACROSS MUCH OF
THE FA WITH THE MOST SIGNIFICANT FACTORS BEING IMPRESSIVE
FRONTOGENESIS H8-H7 EXTENDING FROM THE CATSKILLS NORTHEAST TO
SOUTHERN VERMONT AT 00Z AND THEN SHIFTING TO AN ORIENTATION FROM
JUST EAST OF THE CAPITAL DISTRICT THROUGH THROUGH THE NORTHERN
BERKSHIRES INTO SOUTHERN VERMONT AT 06Z. AS THE EVENING WEARS ON
THE SNOW GROWTH REGION BECOMES INCREASINGLY MORE FAVORABLE WITH
THE -12 TO -18 C TEMP SLICING THROUGH A REGION OF +20 UBAR/SEC. IN
ADDITION IMPRESSIVE EPV EXISTS IN LOWER LEVELS ESPECIALLY BTWN 00Z
AND 06Z. THE LATEST HRRR COL MAX REFLECTIVITY ALSO INDICATES
IMPRESSIVE BANDED PCPN ESPECIALLY ACROSS THE HIGHER TERRAIN IN THE
WARNING AREA BETWEEN 03Z AND 06Z WITH THE BACK EDGE OF THE PCPN
SHIELD EXITING THE FA FROM WEST TO EAST BETWEEN 08Z AND 10Z.
EXPECT LOW TEMPS TONIGHT TO RANGE FROM THE MID 20S NORTHWEST TO
MID 30S FAR SOUTHEAST.
ON THURSDAY EXPECT IMPROVING CONDITIONS WITH HIGH PRESSURE MOVING
IN AND MAINLY DRY CONDITIONS WITH HIGHS RANGING FROM THE UPPER
20S TO LOWER 30S NORTHWEST TO LOWER 40S FAR SOUTHEAST.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
THU NT...BACKING LOW LEVEL WINDS SHOULD ALLOW ANY LINGERING SNOW
BANDS/SNOW SHOWERS TO SHIFT NORTHWARD INTO THE WESTERN
ADIRONDACKS...WITH ADDITIONAL ACCUMS POSSIBLE BEFORE INVERSION
HEIGHTS LOWER AND DIMINISH INTENSITY OF ANY SNOWBANDS.
ELSEWHERE...INITIALLY CLEAR TO PARTLY CLOUDY SKIES SHOULD BECOME
MOSTLY CLOUDY LATER AT NIGHT AS MID LEVEL ISENTROPIC LIFT INCREASES
AHEAD OF NEXT APPROACHING SHORTWAVE. EXPECT MINS TO FALL INTO THE
TEENS AND 20S...WARMEST ACROSS VALLEY REGIONS.
FRI-SAT...UPPER LEVEL TROUGH WILL APPROACH FROM THE W...AND PASS
ACROSS FRI NT. A SFC COLD FRONT ASSOCIATED WITH THIS FEATURE WILL
CROSS THE REGION LATE FRI OR FRI EVE...PRECEDED AND ACCOMPANIED BY
SNOW SHOWERS. THEN...BEHIND THE FRONT...BANDS OF SNOW SHOWERS AND
POSSIBLE SNOW SQUALLS WILL BE POSSIBLE...INITIALLY FAVORING PORTIONS
OF THE WESTERN MOHAWK VALLEY/SCHOHARIE VALLEY...THEN GRADUALLY
SHIFTING NORTHWARD INTO THE WESTERN ADIRONDACKS BY SAT. THERE IS
SOME POTENTIAL FOR LOCALLY HEAVY SNOWFALL AMTS WITHIN SOME OF THESE
BANDS...AND WILL MENTION THIS POSSIBILITY IN THE HWO...WITH GREATEST
THREAT ACROSS THE WESTERN ADIRONDACKS. EXPECT FRI MAXES TO REACH THE
30S IN MOST AREAS...EXCEPT AROUND OR INTO THE LOWER 40S WITHIN THE
VALLEYS...WITH 20S ACROSS HIGHER ELEVATIONS. COLDER AIR BEHIND THE
FRONT WILL MOVE IN FOR FRI NT AND SAT...WITH FRI NT MINS IN THE
TEENS AND LOWER 20S...AND SAT MAXES MAINLY IN THE 30S WITHIN
VALLEYS...AND 20S ACROSS HIGHER ELEVATIONS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THIS PERIOD WILL BE FAIRLY QUIET AS HIGH PRESSURE BUILDS INTO THE
MID ATLANTIC REGION SATURDAY NIGHT AND DOMINATES OUR WEATHER INTO
THE EARLY PART OF THE COMING WEEK. A CHANCE OF SOME LAKE ENHANCED
SNOW SHOWERS SATURDAY NIGHT...THEN DRY UNTIL TUESDAY NIGHT WHEN A
WEAK BOUNDARY BRINGS ABOUT SOME SNOW AND RAIN SHOWERS WEST OF THE
HUDSON VALLEY WEDNESDAY.
THE PERIOD STARTS OFF CHILLY...LOWS FROM AROUND 10 TO 20 ABOVE ON
SUNDAY MORNING...WITH HIGHS SUNDAY ONLY IN THE UPPER 20S TO THE
MID 30S. TEMPERATURES WILL GRADUALLY MODERATE WITH HIGHS RISING
TO THE UPPER 30S AND LOWER 40S BY TUESDAY AFTERNOON.
FOR THE MOST PART...USED HPC GUIDANCE TO POPULATE THE GRIDS.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
WIDESPREAD IFR CONDITIONS ARE EXPECTED THROUGH AT LEAST
08Z/THU...WITH PERHAPS JUST SOME BRIEF IMPROVEMENTS TO MVFR VSBYS AT
TIMES.
RAIN AND DRIZZLE WILL CONTINUE INTO THIS EVENING...WITH SOME PERIODS
OF MODERATE TO HEAVY RAIN POSSIBLE. THEN...A TRANSITION TO WET SNOW
IS TO OCCUR LATER THIS EVENING...ROUGHLY BETWEEN 01Z-03Z/THU AT KGFL
AND KALB...AND NOT UNTIL AFTER 06Z/THU AT KPOU. THE SNOW MAY BE
MODERATE TO HVY IN INTENSITY...ESP AT KALB AND POSSIBLY KPOU.
PRECIPITATION SHOULD DECREASE IN INTENSITY FROM W TO E BETWEEN
07Z-09Z/THU...AND ENDING BY 11Z/THU IN ALL AREAS.
FOR THU...EXPECT MAINLY VFR CONDITIONS...EXCEPT POSSIBLY SOME MVFR
CIGS/VSBY IN ISOLATED SNOW SHOWERS AT KGFL AND KALB LATER IN THE
AFTERNOON.
WINDS WILL REMAIN FROM THE NORTH TO NORTHEAST AT 5-10 KT THIS
AFTERNOON AND EARLY EVENING...THEN SHIFT INTO THE N...THEN NW AND
INCREASE TO 10-20 KT AFTER 05Z/THU. WINDS WILL THEN BACK INTO THE NW
TO W...AND INCREASE TO 15-25 KT AFTER 14Z/THU...WITH SOME GUSTS
POSSIBLY REACHING 30-35 KT AT KALB.
OUTLOOK...
THU NT-SAT...MAINLY VFR...SLIGHT CHC -SHSN. BREEZY.
SUN-MON...VFR...NO SIG WX.
&&
.HYDROLOGY...
A SIGNIFICANT MIXED PRECIPITATION EVENT WAS OCCURRING ACROSS THE
REGION WITH STORM TOTAL LIQUID AMOUNTS FROM LESS THAN A QUARTER
INCH IN NORTHERN HERKIMER COUNTY TO A LITTLE OVER TWO INCHES IN
THE LOWER HUDSON VALLEY OF NEW YORK AND THE LITCHFIELD HILLS OF
CONNECTICUT. OVER COOLER REGIONS SUCH AS THE HIGHER ELEVATIONS OF
THE CATSKILLS...BERKSHIRES...AND GREEN MOUNTAINS OF SOUTHERN
VERMONT A SUBSTANTIAL AMOUNT OF THIS PRECIPITATION IS FORECAST
TO COME AS SNOW. ACROSS OUR SOUTHERNMOST COUNTIES...EASTERN ULSTER
DUTCHESS...AND LITCHFIELD...MOST OF THE PRECIPITATION WILL
COME AS RAIN AND LOCALLY HEAVY AMOUNTS MAY AMOUNT TO ENOUGH TO
RESULT IN SOME MINOR FLOODING OF ROADS AND PARKING AREAS AND
CAUSE RISES OF SEVERAL FEET ON RIVERS AND STREAMS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...FLOOD WATCH THROUGH THURSDAY MORNING FOR CTZ001-013.
NY...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR NYZ047-051-
054-058-063.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR NYZ039>043-
048>050-052-053-059>061-082>084.
FLOOD WATCH THROUGH THURSDAY MORNING FOR NYZ064>066.
MA...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR MAZ001-025.
VT...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR VTZ013-014.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR VTZ015.
&&
$$
SYNOPSIS...11
NEAR TERM...11/SNYDER
SHORT TERM...KL
LONG TERM...RCK
AVIATION...KL
HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS ALBANY NY
655 PM EST WED DEC 7 2011
.SYNOPSIS...
A STORM SYSTEM WILL LIFT NORTHEAST FROM THE DELMARVA REGION THIS
EVENING...TO THE EAST END OF LONG ISLAND AROUND MIDNIGHT...AND
THEN INTO THE GULF OF MAINE THURSDAY MORNING. THIS STORM TRACK
WILL RESULT IN RAIN CHANGING TO SNOW THIS EVENING ACROSS MUCH OF
THE REGION WITH SIGNIFICANT SNOWFALL ACCUMULATIONS OVERNIGHT IN
MANY AREAS. THE HEAVIEST SNOW IS EXPECTED TO FALL ACROSS THE
NORTHERN TACONICS...EASTERN CATSKILLS...BERKSHIRES AND SOUTHERN
GREEN MOUNTAINS. HEAVY RAIN WILL CONTINUE TO FALL OVERNIGHT ACROSS
THE MID HUDSON VALLEY AND LITCHFIELD HILLS.
&&
.NEAR TERM /THROUGH THURSDAY/...
WINTER STORM WARNINGS ARE IN EFFECT FOR TONIGHT FOR THE EASTERN
CATSKILLS...NORTHERN TACONICS...BERKSHIRES AND SOUTHERN GREEN
MOUNTAINS AND WINTER WEATHER ADVISORIES IN EFFECT FOR THE
SOUTHEAST ADIRONDACKS...LAKE GEORGE SARATOGA REGION...EASTERN
MOHAWK VALLEY...SACANDAGA REGION...GREATER CAPITAL DISTRICT AND
CENTRAL TACONICS. A FLOOD WATCH IS IN EFFECT THROUGH THURSDAY
MORNING FOR THE MID HUDSON VALLEY...SOUTHERN TACONICS AND
LITCHFIELD HILLS.
SNOWFALL ACCUMULATIONS ARE GENERALLY EXPECTED TO BE 3 TO 8 INCHES
IN THE ADVISORY AREA AND 5 TO 12 INCHES IN THE WARNING AREA EXCEPT
ACROSS THE CENTRAL AND SOUTHEAST CATSKILLS...NORTHERN BERKSHIRES
AND HIGHER TERRAIN OF THE SOUTHERN GREEN MOUNTAINS WHERE 8 TO 16
INCHES OF SNOW IS EXPECTED. TOTAL RAINFALL AMOUNTS IN THE FLOOD
WATCH AREA ARE EXPECTED TO BE IN THE 1.75 TO 2.25 INCH RANGE.
AS OF 530 PM EST...CLOUD TOPS CONTINUE TO COOL ACROSS THE FA WITH
21Z KALB SOUNDING INDICATING A WARM TONGUE OF 4C AT AROUND 875 MB
WITH THE FREEZING LEVEL AT AROUND 775 MB OR 6.6 KFT. HAVE RECEIVED
A REPORT OF 1 INCH OF SNOW THUS FAR IN CHARLOTTEVILLE IN SCHOHARIE
COUNTY WITH HEAVY WET SNOW AND A TEMP OF 36 DEGREES AT AN
ELEVATION OF AROUND 1500 FEET. EXPECT A RAPID CHANGEOVER TO SNOW
THIS EVENING ACROSS MUCH OF THE FA MAINLY BETWEEN 00Z AND 03Z WITH
VERY HEAVY SNOW EXPECTED TO FALL DURING MUCH OF THE NIGHT BEFORE
TAPERING OFF LATE. THE ONLY AREAS WHICH ARE NOT EXPECTED TO
RECEIVE MUCH SNOW ARE FAR NORTHWEST PORTIONS OF THE FA INCLUDING
THE WESTERN ADIRONDACKS AND WESTERN MOHAWK VALLEY WHERE VERY
LITTLE QPF EXPECTED...NORTHERN FRINGE OF PCPN SHIELD AND FAR
SOUTHEAST PORTION OF FA WHICH WILL REMAIN TOO WARM FOR MUCH IN THE
WAY OF SNOW MAINLY FROM THE MID HUDSON VALLEY EAST TO THE
LITCHFIELD HILLS WHERE A FLOOD WATCH IS IN EFFECT.
MANY FAVORABLE FACTORS FOR HEAVY SNOW ARE IN PLACE ACROSS MUCH OF
THE FA WITH THE MOST SIGNIFICANT FACTORS BEING IMPRESSIVE
FRONTOGENESIS H8-H7 EXTENDING FROM THE CATSKILLS NORTHEAST TO
SOUTHERN VERMONT AT 00Z AND THEN SHIFTING TO AN ORIENTATION FROM
JUST EAST OF THE CAPITAL DISTRICT THROUGH THROUGH THE NORTHERN
BERKSHIRES INTO SOUTHERN VERMONT AT 06Z. AS THE EVENING WEARS ON
THE SNOW GROWTH REGION BECOMES INCREASINGLY MORE FAVORABLE WITH
THE -12 TO -18 C TEMP SLICING THROUGH A REGION OF +20 UBAR/SEC. IN
ADDITION IMPRESSIVE EPV EXISTS IN LOWER LEVELS ESPECIALLY BTWN 00Z
AND 06Z. THE LATEST HRRR COL MAX REFLECTIVITY ALSO INDICATES
IMPRESSIVE BANDED PCPN ESPECIALLY ACROSS THE HIGHER TERRAIN IN THE
WARNING AREA BETWEEN 03Z AND 06Z WITH THE BACK EDGE OF THE PCPN
SHIELD EXITING THE FA FROM WEST TO EAST BETWEEN 08Z AND 10Z.
EXPECT LOW TEMPS TONIGHT TO RANGE FROM THE MID 20S NORTHWEST TO
MID 30S FAR SOUTHEAST.
ON THURSDAY EXPECT IMPROVING CONDITIONS WITH HIGH PRESSURE MOVING
IN AND MAINLY DRY CONDITIONS WITH HIGHS RANGING FROM THE UPPER
20S TO LOWER 30S NORTHWEST TO LOWER 40S FAR SOUTHEAST.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
THU NT...BACKING LOW LEVEL WINDS SHOULD ALLOW ANY LINGERING SNOW
BANDS/SNOW SHOWERS TO SHIFT NORTHWARD INTO THE WESTERN
ADIRONDACKS...WITH ADDITIONAL ACCUMS POSSIBLE BEFORE INVERSION
HEIGHTS LOWER AND DIMINISH INTENSITY OF ANY SNOWBANDS.
ELSEWHERE...INITIALLY CLEAR TO PARTLY CLOUDY SKIES SHOULD BECOME
MOSTLY CLOUDY LATER AT NIGHT AS MID LEVEL ISENTROPIC LIFT INCREASES
AHEAD OF NEXT APPROACHING SHORTWAVE. EXPECT MINS TO FALL INTO THE
TEENS AND 20S...WARMEST ACROSS VALLEY REGIONS.
FRI-SAT...UPPER LEVEL TROUGH WILL APPROACH FROM THE W...AND PASS
ACROSS FRI NT. A SFC COLD FRONT ASSOCIATED WITH THIS FEATURE WILL
CROSS THE REGION LATE FRI OR FRI EVE...PRECEDED AND ACCOMPANIED BY
SNOW SHOWERS. THEN...BEHIND THE FRONT...BANDS OF SNOW SHOWERS AND
POSSIBLE SNOW SQUALLS WILL BE POSSIBLE...INITIALLY FAVORING PORTIONS
OF THE WESTERN MOHAWK VALLEY/SCHOHARIE VALLEY...THEN GRADUALLY
SHIFTING NORTHWARD INTO THE WESTERN ADIRONDACKS BY SAT. THERE IS
SOME POTENTIAL FOR LOCALLY HEAVY SNOWFALL AMTS WITHIN SOME OF THESE
BANDS...AND WILL MENTION THIS POSSIBILITY IN THE HWO...WITH GREATEST
THREAT ACROSS THE WESTERN ADIRONDACKS. EXPECT FRI MAXES TO REACH THE
30S IN MOST AREAS...EXCEPT AROUND OR INTO THE LOWER 40S WITHIN THE
VALLEYS...WITH 20S ACROSS HIGHER ELEVATIONS. COLDER AIR BEHIND THE
FRONT WILL MOVE IN FOR FRI NT AND SAT...WITH FRI NT MINS IN THE
TEENS AND LOWER 20S...AND SAT MAXES MAINLY IN THE 30S WITHIN
VALLEYS...AND 20S ACROSS HIGHER ELEVATIONS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THIS PERIOD WILL BE FAIRLY QUIET AS HIGH PRESSURE BUILDS INTO THE
MID ATLANTIC REGION SATURDAY NIGHT AND DOMINATES OUR WEATHER INTO
THE EARLY PART OF THE COMING WEEK. A CHANCE OF SOME LAKE ENHANCED
SNOW SHOWERS SATURDAY NIGHT...THEN DRY UNTIL TUESDAY NIGHT WHEN A
WEAK BOUNDARY BRINGS ABOUT SOME SNOW AND RAIN SHOWERS WEST OF THE
HUDSON VALLEY WEDNESDAY.
THE PERIOD STARTS OFF CHILLY...LOWS FROM AROUND 10 TO 20 ABOVE ON
SUNDAY MORNING...WITH HIGHS SUNDAY ONLY IN THE UPPER 20S TO THE
MID 30S. TEMPERATURES WILL GRADUALLY MODERATE WITH HIGHS RISING
TO THE UPPER 30S AND LOWER 40S BY TUESDAY AFTERNOON.
FOR THE MOST PART...USED HPC GUIDANCE TO POPULATE THE GRIDS.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
WIDESPREAD IFR CONDITIONS ARE EXPECTED THROUGH AT LEAST 08Z TODAY
DUE TO BOTH LOW CEILINGS AND POOR VISIBILITIES FROM A STORM SYSTEM
LIFTING NORTHEAST FROM THE DELMARVA REGION MOVING ACROSS THE EASTERN
OF LONG ISLAND TO THE GULF OF MAINE BY LATER THIS MORNING.
PERIODS OF RAIN WILL CONTINUE THIS EVENING AND MUCH OF TONIGHT...WITH
THE RAIN HEAVY AT TIMES FROM ALBANY SOUTH...WITH THE RAIN MIXING WITH
AND CHANGING TO SNOW FROM NORTHWEST TO SOUTHEAST STARTING NORTHWEST
OF ALBANY EARLY THIS EVENING AND GRADUALLY WORKING SOUTHWARD. THE
RAIN IS EXPECTED TO MIX AND CHANGE OVER AT ALBANY AROUND 04Z...BUT
NOT MIX OR CHANGE OVER AT POUGHKEEPSIE UNTIL AFTER 07Z. THE RAIN AND
SNOW SHOULD PRETTY MUCH BE OVER WITH BY 10Z WITH VFR FLIGHT CONDITIONS
FOR THE REST OF THE DAY ALTHOUGH SOME MVFR CIGS MAY BE ENCOUNTERED
OVER THE HIGHER TERRAIN WEST OF THE HUDSON VALLEY. WINDS ACROSS THE
REGION WILL GENERALLY BE NORTH OR NORTHEAST WEDNESDAY EVENING...THEN
BACK AROUND TO A MORE WESTERLY DIRECTION DURING THE LATE NIGHT AND
EARLY MORNING HOURS...INCREASING TO AROUND 12 KNOTS WITH GUSTS AS
HIGH AS 25 KNOTS.
OUTLOOK...
TONIGHT-SAT...MAINLY VFR...SLIGHT CHC -SHSN. BREEZY.
SUN-MON...VFR...NO SIG WX.
&&
.HYDROLOGY...
A SIGNIFICANT MIXED PRECIPITATION EVENT WAS OCCURRING ACROSS THE
REGION WITH STORM TOTAL LIQUID AMOUNTS FROM LESS THAN A QUARTER
INCH IN NORTHERN HERKIMER COUNTY TO A LITTLE OVER TWO INCHES IN
THE LOWER HUDSON VALLEY OF NEW YORK AND THE LITCHFIELD HILLS OF
CONNECTICUT. OVER COOLER REGIONS SUCH AS THE HIGHER ELEVATIONS OF
THE CATSKILLS...BERKSHIRES...AND GREEN MOUNTAINS OF SOUTHERN
VERMONT A SUBSTANTIAL AMOUNT OF THIS PRECIPITATION IS FORECAST
TO COME AS SNOW. ACROSS OUR SOUTHERNMOST COUNTIES...EASTERN ULSTER
DUTCHESS...AND LITCHFIELD...MOST OF THE PRECIPITATION WILL
COME AS RAIN AND LOCALLY HEAVY AMOUNTS MAY AMOUNT TO ENOUGH TO
RESULT IN SOME MINOR FLOODING OF ROADS AND PARKING AREAS AND
CAUSE RISES OF SEVERAL FEET ON RIVERS AND STREAMS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...FLOOD WATCH THROUGH THURSDAY MORNING FOR CTZ001-013.
NY...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR NYZ047-051-
054-058-063.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR NYZ039>043-
048>050-052-053-059>061-082>084.
FLOOD WATCH THROUGH THURSDAY MORNING FOR NYZ064>066.
MA...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR MAZ001-025.
VT...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR VTZ013-014.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR VTZ015.
&&
$$
SYNOPSIS...11
NEAR TERM...11/SNYDER
SHORT TERM...KL
LONG TERM...RCK
AVIATION...RCK
HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1238 PM EST TUE DEC 6 2011
.SYNOPSIS...
A COLD FRONT STRETCHING FROM NORTHERN MAINE INTO LOW PRESSURE OVER
WESTERN PENNSYLVANIA WILL SLOWLY SAG SOUTHEAST ACROSS OUR AREA
TONIGHT. A STRONGER LOW WILL FORM OVER THE CAROLINAS WEDNESDAY
AND INTENSIFY RAPIDLY AS IT PASSES CAPE COD EARLY THURSDAY.
SOUTHERN PLAINS HIGH PRESSURE WILL BUILD INTO THE MID ATLANTIC
STATES FRIDAY THEN BE FOLLOWED BY A COLD FRONTAL PASSAGE EARLY
SATURDAY. THERE IS A CHANCE THAT LOW PRESSURE WILL FORM ON THAT
FRONT TO THE EAST OF NEW JERSEY. ANOTHER SOUTHERN PLAINS HIGH
PRESSURE SYSTEM WILL BUILD INTO THE MID ATLANTIC STATES NEXT
SUNDAY AND MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A 14Z SURFACE ANALYSIS PLACED A FRONTAL BOUNDARY DRAPED FROM
NORTHERN NEW ENGLAND TO WESTERN PENNSYLVANIA THEN DOWN TO THE
NORTH-CENTRAL GULF OF MEXICO. A FEW WEAK AREAS OF LOW PRESSURE
WERE ALONG THIS FRONT.
ANOTHER MILD DAY ON TAP ACROSS THE REGION AS A SOUTHERLY FLOW IS
MAINTAINED AHEAD OF A SLOWLY APPROACHING COLD FRONT. THIS BOUNDARY
SHOULD TEND TO TAKE ITS TIME AS THE UPPER-LEVEL FLOW IS NEARLY
PARALLEL TO IT.
SOME MAINLY LIGHTER POCKETS OF RAIN HAVE BEEN MOVING ACROSS PARTS
OF THE CWA THIS MORNING, WITH SOME HEAVIER SHOWERS LOCATES TO OUR
SOUTHWEST OVER VIRGINIA. RAINFALL AMOUNTS TODAY ARE ANTICIPATED
TO BE ON THE LIGHTER SIDE. DID RAISE QPF SLIGHTLY FOR SHOWERS
MOVING FROM DOVER INTO SOUTHERN NJ IN THE NEXT FEW HOURS. LOOKING
AT THE 14Z RUC AND 15Z SREF EXPECT MAJORITY OF RAINFALL TO BE
NORTH OF PHILLY METRO AFTER 20Z, QPF AND POPS REFLECT THAT.
AS FOR TEMPERATURES, WE MOSTLY USED AN EVENLY WEIGHTED BLEND OF THE
GFS/NAM MOS. IF WE GET SOME SUNSHINE TO OCCUR, THE LOCAL
TEMPERATURES ESPECIALLY ACROSS THE EASTERN/SOUTHERN AREAS COULD GET
TO 70 DEGREES AS 925 MB TEMPERATURES ARE FORECAST TO BE NEAR +13C.
MAXIMUM TEMPERATURES ACROSS SOUTHERN SECTIONS HAVE BEEN RAISED
SLIGHTLY BASED ON 17Z METAR OBS. DEWPOINTS HAVE ALSO BEEN RAISED
SLIGHTLY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM WEDNESDAY/...
THE FRONTAL BOUNDARY MENTIONED ABOVE WILL GRADUALLY SETTLE EASTWARD
ACROSS THE REGION DURING THE NIGHT. BASED ON THE SLOW EASTWARD
PROGRESSION AND THE CAA HOLDING OFF UNTIL NEAR DAYBREAK, MOST OF THE
REGION WILL HAVE ANOTHER MILD NIGHT. THERE WILL BE PLENTY OF
MOISTURE ACROSS THE CWA WITHIN THE SOUTHERLY FLOW AHEAD OF THE
BOUNDARY. AS THE THERMAL GRADIENT STARTS TO TIGHTEN ALOFT DURING THE
NIGHT, FRONTOGENETIC FORCING SHOULD RESPOND AND PRODUCE A RIBBON OF
RAIN ACROSS THE AREA. THIS MAY END UP BEING FAIRLY NARROW BUT AT
THIS POINT WE CONTINUED WITH CATEGORICAL POPS SLIDING SOUTHEASTWARD
ACROSS THE REGION DURING THE COURSE OF THE NIGHT. OVERALL, THE
RAINFALL AMOUNTS SHOULD BE ON THE LIGHTER SIDE WITH THE EXCEPTION OF
A MORE FOCUSED AREA OF RAIN DEVELOPING LATE AS SOME OF THE MODEL
GUIDANCE SUGGESTS /ESPECIALLY ACROSS THE CENTRAL AND SOUTHERN
AREAS/. SOME OF THE MODEL PARAMETERS /I.E. SHOWALTER INDEX/ HINTS AT
SOME POSSIBLE INSTABILITY DEVELOPING TONIGHT, HOWEVER FORECAST
SOUNDINGS SHOW LITTLE IN THE WAY OF INSTABILITY GIVEN A RATHER
SATURATED PROFILE. THEREFORE, ANY CONVECTIVE TYPE CONTRIBUTION
SHOULD NOT BE DEEP ENOUGH TO PRODUCE CHARGE SEPARATION DUE TO THE
RATHER LOW INSTABILITY POTENTIAL.
IT APPEARS THAT THE COLD AIR LAGS FOR AWHILE, THEREFORE WE REMOVED
ANY MENTION OF SNOW ACROSS THE FAR NORTHWEST. OTHERWISE, PATCHY FOG
MAY ONCE AGAIN BE ACROSS THE REGION ESPECIALLY ACROSS THE HIGHER
TERRAIN. HOWEVER, GIVEN THE FLOW NOT TO FAR ABOVE THE SURFACE IT WAS
DECIDED TO NOT INCLUDE IT ATTM AS THE OVERALL VISIBILITIES OUTSIDE
OF THE RAIN MAY NOT BE A REAL IMPACT.
AS FOR TEMPERATURES, WE WENT WITH A BLEND OF THE NAM/GFS MOS TO
SPLIT SOMEWHAT OF A DIFFERENCE AT SOME LOCALES.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
PATTERN ALOFT: CHARACTERIZED BY A GENERAL SENSE OF TROUGHING OVER
CENTRAL NORTH AMERICA WITH SEVERAL STRONG SHORT WAVES ROLLING THROUGH
THE TROUGH...ULTIMATELY SHOVING THE CURRENT PLUS 1 SD 500 MB WARM
RIDGE EASTWARD INTO THE CENTRAL ATLC.
THEREFORE...THE LONG PERIOD OF ABOVE NORMAL TEMPERATURES LASTING
MORE THAN TWO WEEKS...WILL GIVE WAY TO SEASONABLY COOL TEMPERATURES
THURSDAY AFTERNOON ONWARD THROUGH THE PERIOD. THE BEST CHANCE FOR
A BELOW NORMAL DAY OR TWO IS SLATED FOR THIS COMING SUNDAY AND
MONDAY.
THE PRIMARY WEATHER MAKER IN THIS FCST PERIOD APPEARS TO BE
WEDNESDAY AND IT MAY RESULT IN MULTIPLE HEADLINES INCLUSIVE OF
ADVISORY SNOW IN E PA AND NW NJ...TO A POSSIBLE FLOOD WATCH FOR
SPOTTY SMALL STREAM FLOODING ALONG THE I95 CORRIDOR TO A BRIEF NW
GALE THU MORNING.
THE DAILIES BELOW...
WEDNESDAY...STRONG SHORT WAVE LIFTING ENE FROM THE SW USA PROMISES
TO BRING HEAVY PRECIPITATION TO THE AREA...MOST OF IT RAIN BUT
NEEDS TO BE CAREFULLY WATCHED FOR A MODERATE SNOW EVENT IN THE NW
SECTOR OF OUR FCST AREA...PARTICULARLY READING TO ALLENTOWN TO
MORRISTOWN NWWD AND ESPECIALLY HIGH TERRAIN WHICH FEATURES THE
POCONOS. SUSPECT 2 TO 4 HRS OF SNOW GROWTH POTENTIAL OF 1 INCH/HR
WHICH IS HIGHLIGHTED IN BOTH THE 00Z/6 GFS/NAM. DEFORMATION ZONE
HEAVY PCPN IN E PA. SNOW ACCUMULATION...IF ANY SHOULD OCCUR
PRIMARILY WED NIGHT. THERE IS CHC OF SPOTTY 6 INCH AMOUNTS ABOVE
1000 FT IN THE POCONOS AND POSSIBLY EXTREME NW NJ NEAR WANTAGE AND
HIGH POINT. NO WATCH ATTM BUT WE MAY NEED TO ISSUE ONE LATER
TODAY. TOP DOWN AND BOX WX TOOLS OFFERED ALMOST IDENTICAL WX GRIDS
AS POSTED AT 315 AM THIS MORNING.
THIS SYSTEM HAS A LIKELIHOOD OF PRODUCING 1 TO NEARLY 2.5 INCHES OF
RAIN IN 12 HRS NEAR I95 WHERE 6 HR FFG VALUES RANGE FROM 1.6 TO 2.6
INCHES AND 12 HR HEADWATER GUIDANCE IS NEAR 2 INCHES. THIS FLAGS THE
POTENTIAL OF SOME SMALL STREAM FLOODING IF 2 INCH VALUES OCCUR AND
AN AFTERNOON ISSUANCE OF A FLOOD WATCH MAY BE NEEDED FOR THE ALREADY
VULNERABLE LOWER FFG AREA INTO THE ILG-PHL-NE NJ METRO REGION.
COLLABORATION PREFERRED TO WAIT ONE MORE FCST CYCLE. WE DO NOTE
THE SREF IS AWFULLY LOW ON ITS QPF FOR THIS EVENT AND FEEL SOMETHING
IS VERY WRONG WITH THE SREF WHEN THE 00Z/6 UK/EC/GGEM OP RUNS AS
WELL AS THE GEFS ARE SO HEAVY.
TEMPS/DEWPOINTS/WINDS WERE GENERALLY 50/50 BLENDED 00Z/6 NCEP MOS
GUIDANCE EXCEPT IN THE 00Z-09Z TIME FRAME WHEN LEANED HEAVILY ON
THE NAM 2M TEMPS PRESUMING PCPN WOULD BE TURNING OVER TO SNOW NW TO
SE.
WE COULD SEE RAIN END AS A MIX TO PHL BUT FOR NOW...MORE
CONSERVATIVE.
THURSDAY...P/S AND BRISK DURING THE DAY AND A MO CLEAR NIGHT. GFS
MEX GUIDANCE LOOKED GOOD.
FRIDAY...A CHILLY START AS HIGH PRESSURE BRIEFLY BUILDS OVERHEAD
WITH LIGHT WIND. HIGH CLOUDS MAY ALREADY BE INCREASING AT DAYBREAK...
AHEAD OF THE NEXT INTENSIFYING TROUGH ALOFT APPROACHING FROM THE
WEST. DID NOT ADJUST POPS FROM THE 330PM KPHI MONDAY FCST SINCE
MOST OF THE POP AND WX ENERGY ON THIS SHIFT WAS DEVOTED TO
WEDNESDAY.
SATURDAY...MAY BE BRIEFLY UNSETTLED WITH THE CFP BUT FOR NOW A
CONSERVATIVE FCST. 00Z/6 MEX GUIDANCE TEMPS BLENDED WITH THE 330
PM FCST FROM YDY. THERE COULD BE A FLY IN THE OINTMENT...IN THE
FORM OF A COASTAL LOW DEVELOPING WHICH IF OCCURRED WOULD REQUIRE
A HEAVIER CLOUD FCST THAN NOW ISSUED AS WELL AS A CHANCE OF PCPN.
FOR NOW...THE CONSERVATIVE NO CHANGE MODE BUT SOME MODEL GUIDANCE
FLAGS THIS LATTER MORE UNSETTLED IDEA.
SUNDAY AND MONDAY...FAIR WX AS SOUTHERN PLAINS HIGH PRESSURE ARRIVES
AND DOMINATES.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
A FRONTAL BOUNDARY WILL GRADUALLY APPROACH THE AREA TODAY INTO
TONIGHT AS A COUPLE OF WEAK AREA OF LOW PRESSURE SYSTEMS TRAVEL
ALONG IT.
A MILD AND MOIST SOUTHERLY FLOW REMAINS IN PLACE ACROSS OUR REGION
AHEAD OF THIS FRONT, WHICH WILL RESULT IN WIDESPREAD CLOUDINESS
THROUGH THE PERIOD. THE CEILINGS ARE EXPECTED TO LOWER AND EXPAND
EASTWARD THROUGH THE DAY BECOMING MVFR ACROSS THE TAF SITES WITH
SOME IFR POSSIBLE IN HEAVIER SHOWERS.
AHEAD OF THE FRONTAL BOUNDARY, WE ARE EXPECTING SOME RAIN TO MOVE
ACROSS A PORTION OF THE AREA AT TIMES THROUGH TONIGHT. THIS MAY BE
IN THE FORM OF A FEW PERIODS OF RAIN FROM WEST TO EAST AND SHOULD BE
MOSTLY ON THE LIGHTER SIDE. WE THEREFORE CONTINUED THE IDEA OF SOME
RAIN AROUND AT TIMES THROUGH THE PERIOD. THE VISIBILITIES ARE
PROBLEMATIC AS IT WILL MAINLY BE DEPENDENT ON THE RAIN AND THE
ASSOCIATED INTENSITY. GIVEN THE AMOUNT OF MOISTURE IN THE AIR, WE
FOCUSED THE REDUCTION IN THE VISIBILITY WITH THE RAIN MENTION AND
THIS MAY SETTLE LOWER ESPECIALLY TONIGHT.
IN SUMMARY, LOWERING CONDITIONS ARE EXPECTED THROUGH THE DAY AND
TONIGHT WITH BOUTS OF RAIN AT TIMES. THE FRONT ITSELF IS EXPECTED
TO GRADUALLY CROSS MOST OF THE TERMINALS TOWARD DAYBREAK WEDNESDAY
WITH A SOUTHERLY WIND UP TO 10 KNOTS SHIFTING TO THE WEST.
OUTLOOK...
WEDNESDAY...ANY MORNING IFR MAY BECOME MVFR OR VFR CIGS FOR A TIME...
MAINLY FAR N PTN OF THE AREA BEFORE DETERIORATING TO IFR IN RAIN
LATE IN THE DAY FROM S TO N. A CHANGE TO 1 TO 6 HRS OF SNOW APPEARS
PROBABLE IN THE KRDG/KABE REGION WED NIGHT WITH BRIEF LIFR CONDS
POCONOS TO KABE WHERE A WET SNOWFALL RATE OF 1/HR IS POSSIBLE FOR
A SHORT TIME. STRONGEST WINDS PROBABLY LATE WED NIGHT WHEN A WSHIFT
TO NW IS EXPECTED BEHIND RAPIDLY DEEPENING AND FAST DEPARTING
COASTAL LOW PRES. NW GUSTS 15 TO 25 KTS BY DAWN THU.
THURSDAY...VFR. NW WIND GUSTS TO 20 OR 25 KTS BECOMING LIGHT AT
NIGHT.
FRIDAY...VFR. LIGHT WIND.
SATURDAY...VFR THOUGH THERE MAY BE A SHORT PERIOD OF MVFR CIGS
DURING THE MORNING.
&&
.MARINE...
A SOUTHERLY FLOW WILL CONTINUE TODAY AND TONIGHT AHEAD OF A SLOW
MOVING COLD FRONT. THIS BOUNDARY IS NOT EXPECTED TO REACH THE WATERS
UNTIL ABOUT DAYBREAK WEDNESDAY. THE FLOW AROUND 925 MB WILL INCREASE
TO ABOUT 35 KNOTS THROUGH TONIGHT. GIVEN THE WAA THOUGH, THIS IS
EXPECTED TO NOT MIX DOWN ALL THAT EFFICIENTLY. THEREFORE, THE WINDS
ARE ANTICIPATED TO REMAIN BELOW ADVISORY CRITERIA. THE SOUTHERLY
FLOW HOWEVER COULD EDGE THE SEAS UP TO 5 FEET ESPECIALLY FOR THE
OFFSHORE WATERS THROUGH TONIGHT. THIS DOES NOT LOOK SOLID, THEREFORE
WE HELD OFF ON AN ADVISORY FOR NOW.
OUTLOOK...
WED/THU...POSSIBLE SCA CONDS ON THE ATLC WATERS FOR A TIME WEDNESDAY
HEADLINED A GALE WATCH FOR LATE WED NIGHT-THU MORNING WHICH WAS
THE MORE IMPORTANT HEADLINE HAZARD. OTRW WIDESPREAD SCA THURSDAY
MORNING WITH A LOW TO MDT PROB OF A 3 TO 6 HR PERIOD OF NW GALES
IN THE 08Z-14Z THURSDAY TIME FRAME.
FRI...QUIET. NO HEADLINE.
SAT...A LITTLE CHOPPY WITH NEXT CFP AND CHC OF SCA CONDS
DEVELOPING.
&&
.HYDROLOGY...
THIS SYSTEM HAS A LIKELIHOOD OF PRODUCING 1 TO NEARLY 2.5 INCHES OF
RAIN IN 12 HRS NEAR I95 WHERE 6 HR FFG VALUES RANGE FROM 1.6 TO 2.6
INCHES AND 12 HR HEADWATER GUIDANCE IS NEAR 2 INCHES. THIS FLAGS THE
POTENTIAL OF SOME SMALL STREAM FLOODING IF 2 INCH VALUES OCCUR AND
AN AFTERNOON ISSUANCE OF A FLOOD WATCH MAY BE NEEDED FOR THE ALREADY
VULNERABLE LOWER FFG AREA INTO THE ILG-PHL-NE NJ METRO REGION.
COLLABORATION PREFERRED TO WAIT ONE MORE FCST CYCLE. WE DO NOTE
THE SREF IS AWFULLY LOW ON ITS QPF FOR THIS EVENT AND FEEL SOMETHING
IS VERY WRONG WITH THE SREF WHEN THE 00Z/6 UK/EC/GGEM OP RUNS AS
WELL AS THE GEFS ARE SO HEAVY.
&&
.CLIMATE...
ALLENTOWN YEARLY RECORD 67.69. SOON TO BE REESTABLISHED WITH
SIGNIFICANTLY HIGHER RECORD VALUES IN 2011.
AS OF 5 AM...67.62.
MEANWHILE THROUGH THE 5TH OF DECEMBER...
KPHL 16 CONSEC DAYS ABOVE NORMAL
KABE 16 CONSEC DAYS ABOVE NORMAL
KTTN 16 CONSEC DAYS AT OR ABOVE NORMAL. NORMAL ON 12/3
KMPO 16 CONSEC DAYS AT OR ABOVE NORMAL. NORMAL ON 12/3
ALL OTHER CLIMO SITES NOT MENTIONED HAD A BELOW NORMAL DAY AT LEAST
ON THE 3RD OF DEC.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...GALE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY MORNING
FOR ANZ450>455.
&&
$$
SYNOPSIS...DRAG
NEAR TERM...GAINES/GORSE/MEOLA
SHORT TERM...GORSE
LONG TERM...DRAG
AVIATION...DRAG/GORSE/MEOLA
MARINE...DRAG/GORSE
HYDROLOGY...
CLIMATE...
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
916 PM EST Wed Dec 7 2011
.UPDATE...
Winds are diminishing this evening, and the wind advisory was
allowed to expire at 00z. At least 3 stations within the forecast
area measured winds gusts of at least 40 mph (KVAD, KAAF, and a
Davis Vantage Pro 2 on St. George Island), and the office peaked
at 39 mph on the roof of the Love Building at FSU.
The focus now turns to the possibility of a light freeze tonight.
Satellite imagery shows a dry slot behind the cold front with
mostly clear skies over a large portion of the forecast area. The
exception is across the far northwestern border where the front
edge of a low cloud deck remains. This low cloud deck is fairly
extensive and extends well back into Alabama and Mississippi. None
of the models have a particularly good handle on these clouds
with the exception of the HRRR, and the HRRR does not push this
cloud cover too far into the forecast area before dissipating
later tonight. The clear skies covering most of the forecast area
will allow temperatures to drop more readily, and with diminishing
winds, a short duration light freeze still remains possible away
from the coast. The 18z MAV has low temperatures ranging from 30
to 34 across the inland locations, and this seems reasonable. The
main change to the previous forecast was to tweak the sky grids to
match the current satellite trends.
&&
.AVIATION...
(Through 00z Friday) The traditional MOS guidance and larger
scale models are not handling the expansive area of stratus that
is situated across much of Mississippi and Alabama right now.
Observations show that CIGS in this stratus are 2000-3000 ft, or
in the upper end of MVFR range. The HRRR (rapid refresh RUC model)
has performed well through TAF issuance time, so it was used as
the basis for this forecast. It gradually builds MVFR ceilings
into DHN around 02z, with some FEW-SCT clouds around 2500 ft also
clipping ABY and ECP late tonight. It slowly scatters out the
stratus, fraying from the edges as drier air progressively works
in. It`s possible that the TAFs are too optimistic at ABY and ECP,
which could see some MVFR ceilings overnight, but with a lack of
model support, we will handle any changes with amendments.
&&
.MARINE...
Advisory level winds and seas will continue through the night
behind a cold front. Winds and seas are expected to subside by
Thursday afternoon as an area of high pressure builds over the
southeast states. A dry cold front is expected to move through
this weekend with an increase in winds and seas to at least
cautionary levels.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 32 58 35 67 42 / 0 0 0 0 0
Panama City 35 58 40 64 44 / 0 0 0 0 0
Dothan 32 56 34 62 39 / 0 0 0 0 0
Albany 32 57 34 64 39 / 0 0 0 0 0
Valdosta 32 58 37 65 41 / 0 0 0 0 0
Cross City 31 62 40 68 44 / 0 0 0 0 0
Apalachicola 38 56 39 65 46 / 0 0 0 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...Freeze Warning from 3 AM to 7 AM CST Thursday for Coffee-Dale-
Geneva-Henry-Houston.
GA...Freeze Warning from 4 AM to 8 AM EST Thursday for Baker-Ben Hill-
Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur-Dougherty-
Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller-Mitchell-
Quitman-Randolph-Seminole-Terrell-Thomas-Tift-Turner-Worth.
FL...Freeze Warning from 4 AM EST /3 AM CST/ to 8 AM EST /7 AM CST/
Thursday for Calhoun-Central Walton-Gadsden-Holmes-Inland
Bay-Inland Dixie-Inland Franklin-Inland Gulf-Inland
Jefferson-Inland Taylor-Inland Wakulla-Inland Walton-
Jackson-Lafayette-Leon-Liberty-Madison-Washington.
GM...Small Craft Advisory until 10 AM EST Thursday for Apalachee Bay-
Coastal waters From Ochlockonee River to Apalachicola FL
out to 20 NM-Coastal waters from Suwannee River to Keaton
Beach FL out 20 NM-Coastal waters from Apalachicola to
Destin FL out 20 NM-Waters from Suwannee River to
Apalachicola FL from 20 to 60 NM-Waters from Apalachicola
to Destin FL from 20 to 60 NM.
&&
$$
UPDATE/MARINE...DVD
AVIATION...Lamers
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1003 PM CST WED DEC 7 2011
.DISCUSSION...
856 PM CST
SMALL UPDATES HAVE BEEN MADE FOR THE REMAINDER OF TONIGHTS
FORECAST...WITH ATTENTION TURNING TO THURSDAY NIGHTS SNOW
POTENTIAL.
VARIABLE CLOUD COVERAGE BY OVERNIGHT IS MAKING IT CHALLENGING ON
THE TEMPERATURE FORECAST. WITH AN INITIAL COLD FRONT CONTINUING
TO LOSE DEFINITION AS IT DRAPES INTO NORTHERN IL...LOW CLOUDS HAVE
DIMINISHED IN COVERAGE. SATELLITE TRENDS AND RUC SOUNDINGS ACROSS
NORTHEAST IL INDICATE TEMPORARY SCATTERED CLOUDS ARE LIKELY TO
CONTINUE TO PROPAGATE SOUTHEAST. CLOUDS ALONG THE MID-LEVEL
BAROCLINIC ZONE SEEN AT 700 MB ON THIS EVENINGS UPPER AIR ANALYSIS
WILL ALSO CONTINUE TO SLOWLY FILTER INTO THE AREA THROUGH THU
MORNING. SO WILL CONTINUE TO ADJUST SKY TRENDS...BUT ALL IN ALL
VARIABLE TO PARTLY CLOUDY WORDING IS PROBABLY THE BEST BET. EVEN
THOUGH THE HOURLY TREND WILL DEPEND HEAVILY ON HOW ANY CLOUDS
UNDULATE IN COVERAGE...LOW TEMPERATURES STILL LOOK ON TRACK.
SCATTERED MID-TEENS ARE FORECAST TOWARDS ROCKFORD AND
STERLING...WITH LOWER TO MID 20S TOWARDS THE LAKE AND INTO
NORTHWEST IN.
A LOOK AT THE LATEST GUIDANCE...08.00 NAM AND 07.21 SREF...AS WELL
AS UPSTREAM TRENDS ARE STARTING TO SUPPORT THE LIKELY SCENARIO
THAT A MINOR ACCUMULATING SNOW EVENT WILL BE SEEN IN THE FORECAST
AREA...ESPECIALLY THE SOUTHEAST QUARTER TO THIRD. THE UPPER AIR
ANALYSES THIS EVENING DEPICTED THE STRONG UPPER JET /OVER 120 KTS
AT UNR/ HEADING TOWARDS THE AREA WHICH WILL PROVIDE MORE
CONCENTRATED UPPER SUPPORT DURING TUE AFTERNOON AND NIGHT.
SATURATION AND QG FORCING WITH THE WAVE WILL NOT ARRIVE INTO
PARTS OF OUR AREA UNTIL THE NIGHT...LIKELY BY 03Z. THE NEW NAM
OUTPUT INDICATES MIXING RATIOS NEAR 2 G/KG ON THE FAVORED SURFACES
WHERE LIFT IS OCCURRING INTO THE FAR SOUTHEAST...AND THAT IS
NEARLY COINCIDENT WITH THE DENDRITIC GROWTH AREA. WHILE TOP-DOWN
METHODS ON THE NAM SOUNDINGS WARM SOME ON THE WAY DOWN...RATIOS
STILL LOOK TO BE ON THE HIGHER SIDE AS INDICATED BY EVEN THE
PRIOR NAM RUNS. THE SREF GUIDANCE HAS BECOME MORE FOCUSED ON ITS
SNOW PROBABILITIES...INDICATING A RIBBON ACROSS THE SOUTHEAST
/GIBSON CITY TO RENSSELAER/ WHERE OVER ONE INCH OF SNOW IS
FORECAST BY THE MEAN OF THE MEMBERS. EVEN THE PRIOR RUNS OF THESE
MODELS AND THE GFS...EC...AND NMM WRF...INDICATE THE FAR SOUTHERN
TIER OF COUNTIES TO SEE SNOW...AND COULD ENVISION BASED ON RATIOS
AND RECENTLY COOLED GROUND TEMPERATURES THAT ONE TO TWO INCH
ACCUMULATIONS ARE POSSIBLE. MINOR ACCUMULATIONS OF A COUPLE TENTHS
AS FAR NORTH AS CHICAGO CANNOT BE RULED OUT DEPENDING ON IF THE
ATMOSPHERE CAN SATURATE...AND LIGHT AMOUNTS ARE FORECAST THAT FAR
NORTH BY THE 18.00 NAM. WILL RE-ISSUE AN SPS TO HIGHLIGHT FOR NOW
AND BRIEF THE OVERNIGHT SHIFT.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 04Z...
*SLIGHT THREAT OF -SN THU EVENING.
TRS
//DISCUSSION...UPDATED 02Z...
AREA OF MVFR STRATOCU THAT WAS OVER SOUTHERN WI AND FAR N CENTRAL
IL HAS ALL BUT DISSIPATED OVER THE LAST COUPLE HRS THOUGH AN AREA
OF STRATUS HAS GROWN OVER FAR NE IA AND PORTIONS OF SW IA.
WITH LOSS OF ORIGINAL MVFR CLOUDS HAS DUMPED THE TEMPO MVFR CIG
GROUP THAT WAS IN TIL 03Z. WHILE NEW UPSTREAM STRATUS PATCH
CURRENTLY MOVING TO THE SE...FORECAST WINDS OVER LOCAL AREA HAVE
MORE OF A WESTERLY COMPONENT SO EXPECT SOUTHERN EDGE OF THESE
CLOUDS TO REMAIN N OF CHI AREA. SMALL POTENTIAL TO BE IN RFD VC FOR
A PD THIS EVE BUT HAVE ONLY SCT020 IN RFD TAFOR FOR THIS EVE.
PREVIOUS DISCUSSION...UPDATED 00Z...
SFC TROF/WEAK COLD FRONT AND ASSOCIATED SLIGHT VEERING OF WINDS
HAS MOVED TO JUST S OF THE WI STATE LINE AT 00Z. THE TROF
PROCEEDED PATCHY AREAS OF MVFR STRATOCU CIGS SO HAVE A COUPLE HR
TEMPO GROUP OF BKN022 IN THE 01Z TO 03Z WINDOW FOR CHI AREA.
THEREAFTER...THESE LOWER CLOUDS MOVE OFF TO THE SSE WITH JUST SOME
ALTOCUMULUS MOVING E ACROSS THE MS RIVER AHEAD OF THE SHORT WAVE
ROTATING SE OVER THE NORTHERN HI PLAINS.
LIGHT WINDS WINDS BACK TO WSW OVERNIGHT IN RESPONSE TO APPROACHING
NORTHERN HI PLAINS SYSTEM AND ANOTHER COLD FRONT DROPPING SE
ACROSS WI DURG THE DAY THU. THIS SYSTEM IS EXPECTED TO PRODUCE
SOME LIGHT SNOWFALL BUT ZONE OF BEST FORCING AT THIS POINT LOOKS
ALONG A NORTHERN MO...CENTRAL IL...NE IND AXIS SO THREAT OF ANY
PRECIPITATION AT THE LOCAL TERMINALS QUITE SMALL.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 04Z...
*HIGH CONFIDENCE ALL FORECAST ELEMENTS.
TRS
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
*
FRIDAY...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...VFR INTO EVENING...SLGT CHC -SN PRODUCING MVFR CIGS
AND/OR VSBYS OVERNIGHT.
TUESDAY...MVFR CIGS POSSIBLE.
*
TRS
&&
.MARINE...
157 PM CST
A COLD FRONT MOVING ACROSS LAKE SUPERIOR AND WISCONSIN THIS
AFTERNOON WILL MOVE ACROSS LAKE MICHIGAN LATER THIS AFTERNOON AND
EVENING. THIS WILL HELP KEEP THE WINDS AROUND 25 TO 30 KT TONIGHT AS
THE WINDS BECOME NORTHWESTERLY. A PROLONGED PERIOD OF BRISK WEST TO
NORTHWESTERLY WINDS IS EXPECTED INTO SATURDAY AS HIGH PRESSURE
MOVING FROM THE PLAINS EASTWARD ACROSS THE MID MISSISSIPPI
VALLEY...WILL CONTINUE TO PRODUCE A DECENT PRESSURE GRADIENT ACROSS
THE GREAT LAKES.
LATER SATURDAY THE WINDS LOOK TO SWITCH OUT OF THE SOUTHWEST AND
INCREASE TO AROUND 30 KT AGAIN AS THE SURFACE HIGH SHIFTS ACROSS THE
OHIO VALLEY AND ANOTHER AREA OF LOW PRESSURE MOVES ACROSS THE
PRAIRIE PROVIDENCES OF CANADA. IT APPEARS THAT THESE SOUTHWESTERLY
WINDS WILL CONTINUE INTO EARLY NEXT WEEK AS THE SURFACE HIGH
CONTINUES TO DOMINATE ACROSS EASTERN CONUS. THERE COULD EVEN BE A
PERIOD OF LOW END GALE FORCE WINDS DURING THIS PERIOD.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO BURNS HARBOR UNTIL
10 PM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN UNTIL 10 AM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
856 PM CST WED DEC 7 2011
.DISCUSSION...
856 PM CST
SMALL UPDATES HAVE BEEN MADE FOR THE REMAINDER OF TONIGHTS
FORECAST...WITH ATTENTION TURNING TO THURSDAY NIGHTS SNOW
POTENTIAL.
VARIABLE CLOUD COVERAGE BY OVERNIGHT IS MAKING IT CHALLENGING ON
THE TEMPERATURE FORECAST. WITH AN INITIAL COLD FRONT CONTINUING
TO LOSE DEFINITION AS IT DRAPES INTO NORTHERN IL...LOW CLOUDS HAVE
DIMINISHED IN COVERAGE. SATELLITE TRENDS AND RUC SOUNDINGS ACROSS
NORTHEAST IL INDICATE TEMPORARY SCATTERED CLOUDS ARE LIKELY TO
CONTINUE TO PROPAGATE SOUTHEAST. CLOUDS ALONG THE MID-LEVEL
BAROCLINIC ZONE SEEN AT 700 MB ON THIS EVENINGS UPPER AIR ANALYSIS
WILL ALSO CONTINUE TO SLOWLY FILTER INTO THE AREA THROUGH THU
MORNING. SO WILL CONTINUE TO ADJUST SKY TRENDS...BUT ALL IN ALL
VARIABLE TO PARTLY CLOUDY WORDING IS PROBABLY THE BEST BET. EVEN
THOUGH THE HOURLY TREND WILL DEPEND HEAVILY ON HOW ANY CLOUDS
UNDULATE IN COVERAGE...LOW TEMPERATURES STILL LOOK ON TRACK.
SCATTERED MID-TEENS ARE FORECAST TOWARDS ROCKFORD AND
STERLING...WITH LOWER TO MID 20S TOWARDS THE LAKE AND INTO
NORTHWEST IN.
A LOOK AT THE LATEST GUIDANCE...08.00 NAM AND 07.21 SREF...AS WELL
AS UPSTREAM TRENDS ARE STARTING TO SUPPORT THE LIKELY SCENARIO
THAT A MINOR ACCUMULATING SNOW EVENT WILL BE SEEN IN THE FORECAST
AREA...ESPECIALLY THE SOUTHEAST QUARTER TO THIRD. THE UPPER AIR
ANALYSES THIS EVENING DEPICTED THE STRONG UPPER JET /OVER 120 KTS
AT UNR/ HEADING TOWARDS THE AREA WHICH WILL PROVIDE MORE
CONCENTRATED UPPER SUPPORT DURING TUE AFTERNOON AND NIGHT.
SATURATION AND QG FORCING WITH THE WAVE WILL NOT ARRIVE INTO
PARTS OF OUR AREA UNTIL THE NIGHT...LIKELY BY 03Z. THE NEW NAM
OUTPUT INDICATES MIXING RATIOS NEAR 2 G/KG ON THE FAVORED SURFACES
WHERE LIFT IS OCCURRING INTO THE FAR SOUTHEAST...AND THAT IS
NEARLY COINCIDENT WITH THE DENDRITIC GROWTH AREA. WHILE TOP-DOWN
METHODS ON THE NAM SOUNDINGS WARM SOME ON THE WAY DOWN...RATIOS
STILL LOOK TO BE ON THE HIGHER SIDE AS INDICATED BY EVEN THE
PRIOR NAM RUNS. THE SREF GUIDANCE HAS BECOME MORE FOCUSED ON ITS
SNOW PROBABILITIES...INDICATING A RIBBON ACROSS THE SOUTHEAST
/GIBSON CITY TO RENSSELAER/ WHERE OVER ONE INCH OF SNOW IS
FORECAST BY THE MEAN OF THE MEMBERS. EVEN THE PRIOR RUNS OF THESE
MODELS AND THE GFS...EC...AND NMM WRF...INDICATE THE FAR SOUTHERN
TIER OF COUNTIES TO SEE SNOW...AND COULD ENVISION BASED ON RATIOS
AND RECENTLY COOLED GROUND TEMPERATURES THAT ONE TO TWO INCH
ACCUMULATIONS ARE POSSIBLE. MINOR ACCUMULATIONS OF A COUPLE TENTHS
AS FAR NORTH AS CHICAGO CANNOT BE RULED OUT DEPENDING ON IF THE
ATMOSPHERE CAN SATURATE...AND LIGHT AMOUNTS ARE FORECAST THAT FAR
NORTH BY THE 18.00 NAM. WILL RE-ISSUE AN SPS TO HIGHLIGHT FOR NOW
AND BRIEF THE OVERNIGHT SHIFT.
MTF
&&
PREVIOUS DISCUSSION...
820 PM CST
MAIN FORECAST ISSUES ARE WITH SNOW CHANCES ACROSS THE CWA THURSDAY
NIGHT INTO EARLY FRIDAY...ALTHOUGH CONFIDENCE IS LOWERING OF THIS
POSSIBILITY AT THIS TIME.
RATHER QUIET CONDITIONS TO START THE FORECAST PERIOD AT THIS
TIME...DESPITE A MID LEVEL WAVE AND ATTENDANT SURFACE REFLECTION
SHIFTING SOUTHEAST THROUGH THE REGION. PRECIPITATION IS ONCE AGAIN
NOT EXPECTED AS THESE WEAK FEATURES PUSH ACROSS THE CWA LATE THIS
AFTERNOON INTO THE EVENING. WHAT CAN BE EXPECTED THIS EVENING IS
AN INCREASE IN CLOUD COVER. THE PARTLY CLOUDY SKIES CURRENTLY IN
PLACE WILL BE REPLACED WITH A DECK OF LOW LEVEL MOISTURE
ASSOCIATED WITH THIS SURFACE TROUGH. DUE EXPECT MOST OF NORTHERN
ILLINOIS TO OBSERVE A PERIOD OF CLOUDY TO PARTLY CLOUDY SKIES THIS
EVENING...BUT EXPECT THIS LOW LEVEL MOISTURE TO SCATTER/ERODE WITH
THIS TROUGH BECOMING MORE DIFFUSE. ALTHOUGH AS THIS OCCURS
UPSTREAM MID LEVEL MOISTURE TO THE WEST WILL CONTINUE TO DROP
SOUTH/SOUTHEAST WITH TIME TONIGHT AND CONTINUE TO PROVIDE AT LEAST
PARTLY CLOUDY SKIES. WITH A BRIEF RETURN TO ZONAL FLOW ALOFT AND
SURFACE RIDGING...MOST OF THE THURSDAY APPEARS TO BE QUIET BUT
WITH AN INCREASE IN CLOUD COVER AS A UPPER LEVEL TROUGH DIGS
SOUTHEAST OUT OF THE NORTHERN PLAINS.
OUTSIDE OF SOME PERSISTENT LAKE EFFECT SNOW SHOWERS FOR THE
EASTERN HALF OF LAKE MICHIGAN AND A PERIOD OF DRIER WEATHER
TONIGHT AND MOST OF THE DAY THURSDAY FOR THE CWA...CHANCES FOR
SNOW WILL BEGIN TO INCREASE LATE IN THE DAY ON THURSDAY. ALTHOUGH
THE CURRENT TREND OF BETTER CHANCES/HIGHER POPS ACROSS THE
SOUTHERN HALF OF THE CWA REMAINS...THERE STILL REMAINS SOME
UNCERTAINTY AS TO THE TIMING OF THE NEXT BIG PUSH OF COLDEST AIR
ALOFT. THIS WILL THEN AFFECT THE PLACEMENT OF AN APPROACHING MID
LEVEL BAROCLINIC ZONE AND RESULTANT FRONTOGENETICAL FORCING...OUT
AHEAD OF A DIGGING UPPER LEVEL TROUGH. THE 12Z NAM CURRENTLY
APPEARS TO THE MORE AGGRESSIVE OF THE MODELS BRINGING THIS MID
LEVEL BAROCLINIC ZONE THE FURTHEST SOUTH KEEPING THE ASSOCIATED
FORCING/QPF ALSO THE FURTHEST SOUTH...AND EVEN OUT OF THE CWA.
WHILE THE GFS AND ECMWF HAVE THIS FORCING FURTHER NORTH. NOW
FURTHER NORTH MEANING CHANCES FOR A POSSIBLE ACCUMULATING SNOW
ACROSS THE SOUTHEAST PORTION OF THE CWA. IT WOULD APPEAR WITH
LATEST GUIDANCE THAT CHANCES FOR ACCUMULATING SNOW ACROSS MUCH OF
THE CWA IS NOT LOOKING THE GREATEST...AND POSSIBLY FOR EVEN ANY
SNOWFALL AT ALL. LOOKING AT VARIOUS CROSS SECTIONS ACROSS THE
REGION FOR THIS PERIOD...THE SETUP DOES NOT APPEAR THE GREATEST.
OVERALL FORCING AS WELL AS ANY PERSISTENT DEFINED VERTICAL MOTION
APPEARS TO MEAGER AT MOST. WITH THE AMOUNT OF DRIER AIR WHICH WILL
BE IN PLACE...I WONDER IF WHATEVER FORCING WILL BE PRESENT WILL BE
SPENT SATURATING THE COLUMN. IF THIS SATURATION WERE TO OCCUR...IT
APPEARS THAT IT WILL BE FOR OUR FAR SOUTHEAST PORTION OF THE CWA
IF NOT JUST TO THE SOUTH. ALSO...THROW IN THE FACT THAT ALL LATEST
HIRES DATA IS HINTING AT THE POSSIBILITY OF A SNOW LESS THURSDAY
NIGHT BY KEEPING ANY QPF JUST TO THE SOUTH OF THE CWA. WITH THIS
IN MIND...HAVE STARTED THE TREND OF LOWERING POPS ACROSS MOST OF
THE CWA. ALTHOUGH HAVE LEFT THE FAR SOUTHEAST AT CHANCE POPS WITH
STILL SOME UNCERTAINTY AT THIS TIME. IF CURRENT TRENDS
CONTINUE...POPS ACROSS THIS AREA WILL ALSO SEE THIS LOWERING
TREND. IF SNOW DOES DEVELOP...ANY ACCUMULATION WILL BE AROUND THE
HALF INCH MARK WITH AT MOST AN INCH AND WOULD BE CONFINED TO AREAS
SOUTH OF INTERSTATE 80. ALTHOUGH CURRENT TRENDS ARE FOR A MORE
SOUTHERLY TRACK OF THIS FORCING AND ASSOCIATED SNOWFALL...MODELS
DO CONTINUE TO VARY FROM ONE RUN TO THE NEXT. EVEN IF THE TRACK
WERE TO BE FURTHER NORTH THAN WHAT IS CURRENTLY EXPECTED WITH THE
NEXT RUNS...STILL DONT FEEL IT WOULD BE FAR NORTH ENOUGH TO
PROVIDE AN ACCUMULATING SNOWFALL FOR THE NORTHERN HALF OF THE CWA.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 02Z...
* VEERING OF AOB 10KT WINDS FM WSW-W TO W-WNW DURING EARLY-MID
EVENING.
* STRATUS WITH BASES 010-015 FAR NE IA TO PORTIONS OF SW WI
EXPANDING.
* SLIGHT THREAT OF -SN THU EVENING.
TRS
//DISCUSSION...UPDATED 02Z...
AREA OF MVFR STRATOCU THAT WAS OVER SOUTHERN WI AND FAR N CENTRAL
IL HAS ALL BUT DISSIPATED OVER THE LAST COUPLE HRS THOUGH AN AREA
OF STRATUS HAS GROWN OVER FAR NE IA AND PORTIONS OF SW IA.
WITH LOSS OF ORIGINAL MVFR CLOUDS HAS DUMPED THE TEMPO MVFR CIG
GROUP THAT WAS IN TIL 03Z. WHILE NEW UPSTREAM STRATUS PATCH
CURRENTLY MOVING TO THE SE...FORECAST WINDS OVER LOCAL AREA HAVE
MORE OF A WESTERLY COMPONENT SO EXPECT SOUTHERN EDGE OF THESE
CLOUDS TO REMAIN N OF CHI AREA. SMALL POTENTIAL TO BE IN RFD VC FOR
A PD THIS EVE BUT HAVE ONLY SCT020 IN RFD TAFOR FOR THIS EVE.
PREVIOUS DISCUSSION...UPDATED 00Z...
SFC TROF/WEAK COLD FRONT AND ASSOCIATED SLIGHT VEERING OF WINDS
HAS MOVED TO JUST S OF THE WI STATE LINE AT 00Z. THE TROF
PROCEEDED PATCHY AREAS OF MVFR STRATOCU CIGS SO HAVE A COUPLE HR
TEMPO GROUP OF BKN022 IN THE 01Z TO 03Z WINDOW FOR CHI AREA.
THEREAFTER...THESE LOWER CLOUDS MOVE OFF TO THE SSE WITH JUST SOME
ALTOCUMULUS MOVING E ACROSS THE MS RIVER AHEAD OF THE SHORT WAVE
ROTATING SE OVER THE NORTHERN HI PLAINS.
LIGHT WINDS WINDS BACK TO WSW OVERNIGHT IN RESPONSE TO APPROACHING
NORTHERN HI PLAINS SYSTEM AND ANOTHER COLD FRONT DROPPING SE
ACROSS WI DURG THE DAY THU. THIS SYSTEM IS EXPECTED TO PRODUCE
SOME LIGHT SNOWFALL BUT ZONE OF BEST FORCING AT THIS POINT LOOKS
ALONG A NORTHERN MO...CENTRAL IL...NE IND AXIS SO THREAT OF ANY
PRECIPITATION AT THE LOCAL TERMINALS QUITE SMALL.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 02Z...
* HIGH CONFIDENCE ALL FORECAST ELEMENTS.
TRS
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
*
FRIDAY...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...VFR INTO EVENING...SLGT CHC -SN PRODUCING MVFR CIGS
AND/OR VSBYS OVERNIGHT.
TUESDAY...MVFR CIGS POSSIBLE.
*
TRS
&&
.MARINE...
157 PM CST
A COLD FRONT MOVING ACROSS LAKE SUPERIOR AND WISCONSIN THIS
AFTERNOON WILL MOVE ACROSS LAKE MICHIGAN LATER THIS AFTERNOON AND
EVENING. THIS WILL HELP KEEP THE WINDS AROUND 25 TO 30 KT TONIGHT AS
THE WINDS BECOME NORTHWESTERLY. A PROLONGED PERIOD OF BRISK WEST TO
NORTHWESTERLY WINDS IS EXPECTED INTO SATURDAY AS HIGH PRESSURE
MOVING FROM THE PLAINS EASTWARD ACROSS THE MID MISSISSIPPI
VALLEY...WILL CONTINUE TO PRODUCE A DECENT PRESSURE GRADIENT ACROSS
THE GREAT LAKES.
LATER SATURDAY THE WINDS LOOK TO SWITCH OUT OF THE SOUTHWEST AND
INCREASE TO AROUND 30 KT AGAIN AS THE SURFACE HIGH SHIFTS ACROSS THE
OHIO VALLEY AND ANOTHER AREA OF LOW PRESSURE MOVES ACROSS THE
PRAIRIE PROVIDENCES OF CANADA. IT APPEARS THAT THESE SOUTHWESTERLY
WINDS WILL CONTINUE INTO EARLY NEXT WEEK AS THE SURFACE HIGH
CONTINUES TO DOMINATE ACROSS EASTERN CONUS. THERE COULD EVEN BE A
PERIOD OF LOW END GALE FORCE WINDS DURING THIS PERIOD.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO BURNS HARBOR UNTIL
10 PM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN UNTIL 10 AM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
200 PM CST TUE DEC 6 2011
.DISCUSSION...
304 AM CST
FORECAST HIGHLIGHTS TODAY INCLUDE LAKE EFFECT PRECIP TODAY...CLOUD
TRENDS THROUGH TONIGHT...POTENTIAL LIGHT SNOW EVENT THURSDAY NIGHT
PRIOR TO THE ARRIVAL OF SEASONS COLDEST AIR MASS LATE IN THE WEEK.
VERY LITTLE CHANGE IS EXPECTED TO WINDS/STABILITY OVER THE LAKE
THROUGH MIDDAY...SO GENERALLY EXPECTING A CONTINUATION OF LIGHT
NUISANCE TYPE LAKE EFFECT RAIN/SNOW SHOWERS THROUGH THIS MORNING
OVER NORTHEAST ILLINOIS. P-TYPE SHOULD BE MOSTLY RAIN NEAR THE LAKE
WITH GREATER THREAT OF SNOW MIXTURE INLAND. EVEN WHERE PRECIP
CHANGES TO ALL SNOW TEMPS SHOULD MOSTLY BE TOO WARM TO ALLOW FOR
ANYTHING MORE THAN A BRIEF DUSTING AT WORST. WINDS WILL BEGIN
BACKING THIS AFTERNOON SENDING THE SCATTERED LIGHT LAKE EFFECT
PRECIP EASTWARD MORE INTO NW INDY THIS AFTERNOON BEFORE MOVING EAST
AND OUT OF OUR CWA TOWARD EVENING.
REGARDING CLOUDINESS TODAY...TIS THE SEASON FOR STRATUS AS EVENING
RAOBS ACROSS THE REGION SHOWED A RATHER TEXT BOOK STRATUS SOUNDING
WITH MOISTURE BENEATH A SHARP FRONTAL INVERSION. HAVE SEEN SOME
BREAKS IN THE STRATUS OVER IN EASTERN WI AND COULD SEE A FEW HOLES
FROM TODAY OVER MAINLY NE IL...BUT AS FLOW BACKS TO THE NORTHWEST
WOULD ANTICIPATE THE STRATUS DECK TO OUR WEST TO ADVECT EASTWARD
AND KEEP US FAIRLY SOCKED IN THROUGH TODAY AND INTO THIS EVENING.
HAVE OPTED TO GO SOMEWHAT OPTIMISTIC WITH CLEARING TONIGHT FROM
THE WEST...AND HANG ONTO CLOUDS LONGER THAN ANY GUIDANCE WOULD
SUGGEST AS MODELS ARE NOTORIOUS FOR STRUGGLING WITH SHALLOW COOL
SEASON STRATUS. GIVEN THE EXPECTATION OF CLOUD COVER HAVE GONE
AHEAD AND RAISED LOW TEMPS TONIGHT...PARTICULARLY SOUTHEAST CWA.
STRONG SHORTWAVE PASSES WELL TO OUR SOUTH WEDNESDAY AS LONG WAVE
TROUGH RELOADS TO OUR NORTHWEST AND IS PREPARED TO TAKE AN ARCTIC
DUMP ON US LATER THIS WEEK. PROBABLY THE MOST CONTENTIOUS PART OF
THE FORECAST REVOLVES AROUND THE POTENTIAL FOR SOME ACCUMULATING
SNOW THURSDAY NIGHT. GLOBAL MODELS ALL GENERALLY AGREE ON
DEVELOPING A TIGHTENING LOW/MID LEVEL BAROCLINIC ZONE IN ADVANCE
OF VIGOROUS SHORTWAVE MOVING INTO THE WESTERN GREAT LAKES REGION
THURSDAY NIGHT. MODELS CONTINUE TO HINT AT THE DEVELOPMENT OF BAND
OF LIGHT FRONTOGENTICALLY DRIVEN PRECIP IN ADVANCE OF THIS
SHORTWAVE WHICH COULD BE ENOUGH TO PRODUCE A NARROW BAND OF AN
INCH OR SO OF SNOW. THE DEVIL IS IN THE DETAILS HOWEVER AS THE
AREA TO SEE THAT SNOWFALL WOULD LIKELY TO BE FAIRLY SMALL AND
MODELS HAVE BEEN BOUNCING AROUND A BIT WITH RESPECT TO THE
PLACEMENT OF THE HEAVIEST (ALBEIT STILL LIGHT) PRECIP. THE WRF-NMM
AND WRF-ARW SUGGEST MOISTURE WILL BE TOO LIMITED AND FORCING TOO
FAR SOUTH TO SERIOUSLY THREATEN OUR CWA WITH SUPPORT FROM THE
CANADIAN MODEL. HAVING SAID ALL OF THIS...IT REALLY EQUATES TO
LITTLE CHANGE FROM PREVIOUS FORECAST WITH SLIGHT CHANCE TO LOW END
CHANCE POPS ACROSS THE CWA THURSDAY NIGHT.
CWA WILL THEN GET SIDE-SWIPED BY A BITTERLY COLD EARLY SEASON SHOT
OF ARCTIC AIR FRIDAY INTO FRIDAY NIGHT WITH H8 TEMPS PROGGED TO DROP
TO -15C OR COLDER. TEMPS FRIDAY LOOK TO BE FAIRLY STEADY AND MAY
EVEN FALL A BIT AS HEART OF ARCTIC AIR ARRIVES. SAVING GRACE WITH
THIS COLD SNAP IS THE LACK OF SNOW COVER HERE AND UPSTREAM LIKELY
ALLOWING IT TO MODIFY SOMEWHAT. EVEN SO TEMPS IN THE 20 LOOK LIKELY
FRIDAY WITH LOWS IN THE TEENS FRIDAY NIGHT AWAY FROM THE CITY.
PATTERN PROGGED TO REMAIN VERY PROGRESSIVE WITH BITTER COLD GETTING
SHOVED QUICKLY EASTWARD OVER THE WEEKEND AS A UPPER FLOW TRANSITIONS
TO MORE ZONAL. INCREASINGLY STRONG SOUTHWESTERLY WINDS SHOULD SEND
TEMPS BACK TO NEAR IF NOT ABOVE NORMAL BY SUNDAY INTO MONDAY WITH
LITTLE TO NO THREAT OF ANY PRECIP FRIDAY AFTERNOON THROUGH MONDAY.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* POTENTIAL LAKE EFFECT SNOW SHOWERS EARLY-MID AFTERNOON.
* LIGHT SNOW APPROACHING FROM THE SW.
* VARIABLE VFR/MVFR CIGS INTO THIS EVENING.
TRS
//DISCUSSION...UPDATED 18Z...
AREA OF RADAR ECHOES CONTINUES TO MOVE NORTHEASTWARD OVER N
CENTRAL IL AND APPROACHING METRO NE IL. LIGHT SNOW HAS BEEN
REPORTED AT DVN...MLI...GBG...PIA...C75 WHERE SURFACE DEW POINT
DEPRESSIONS ONLY 1 TO 3 DEG F. WITH MODELS DAMPENING OUT THE
SHORT WAVE FORCING THIS -SN AS IT CONTINUES NORTHEASTWARD FROM NW
MO...SE IA...W CENTRAL IL THIS AFTERNOON AND AN INCREASINGLY
ANTICYCLONIC LOW LEVEL FLOW AS THE SURFACE RIDGE CONTINUES TO
BUILD SOUTHEASTWARD FROM THE UPPER MIDWEST AND MID MO
VALLEY...ALONG WITH MUCH DRIER LOW LEVEL AIR WITH DEW POINTS ONLY
IN THE TEENS TO LOWER 20S F ACROSS NORTHERN IL DO NOT ANTICIPATE
ANY OF THIS PRECIP TO REACH THE GROUND AT THE LOCAL TERMINALS.
TRAJECTORY OF COLD AIR DOWN LAKE MI HAS POTENTIAL TO BRING LAKE
EFFECT SNOW SHOWERS TO NE IL THIS AFTERNOON. VISIBLE SATELLITE
LOOP SHOWING A LAKE EFFECT BAND HAS SPREAD SOUTHWARD FROM E OF
MTW TO E OF ETB LAST COUPLE HOURS. LATEST RUNS OF RUC13 CONTINUE
TO BRING LIGHT PRECIP TO THE IL SHORE 1BETWEEN 18Z AND 19Z. OTHER
HIGH RESOLUTION MODELS LESS AGGRESSIVE AND ONLY SPIT OUT SPOTTY
0.01 QPF AMOUNTS OVER THE WATER. TEMPERATURE INVERSION PER
FORECAST TEMPERATURE PROFILES AND VERIFIED BY ACARS DATA SHOW BASE
TO BE LOCATED BETWEEN 050 AND 060 AGL WHICH WOULD BE DEEP ENOUGH
FOR SOME LIGHT LAKE EFFECT THOUGH AS MENTIONED ABOVE LOW LEVEL
FLOW BECOMES MORE ANTICYCLONIC WITH TIME THIS AFTERNOON AND DRY
AIR IN PLACE OVER FAR NE IL AND UPSTREAM. RAC HAS HAD A PERSISTENT
NNE WIND OFF THE LAKE ALL MORNING AND DEW POINT THERE HELD AT ONLY
22Z UNTIL 17Z WHEN IT DROPPED TO 20F. A LOW CHANCE OF SOME LAKE
EFFECT SHOWERS REACHING VC ORD AND/OR MDW STILL EXISTS SO HAVE
KEPT MENTION OF VCSH THESE SITES 20Z-23Z.
REGARDING CEILINGS THIS AFTERNOON...METARS FROM NEAR THE SE WI
AND NE IL SHORES SHOW THEM CONTINUING TO HOVER AROUND 030.
EXPECT AT LEAST AREAS OF CIGS AROUND 030 THESE AREAS UNTIL FLOW
AT CLOUD LEVEL BACKS TO N AND NW LATER AFTERNOON AND THIS EVENING.
A PERSISTENT AREA OF MVFR STRATUS/STRATOCU HAS BEEN IN PLACE OVER
NW WI...FARR SE MN...EASTERN IA...AND NE THROUGH SOUTHERN MO AHEAD
OF THE SURFACE RIDGE AXIS. EXPECT THESE CLOUDS TO SHIFT E TO SE AS
DOES THE RIDGE DURING THE AFTERNOON AND EVENING BUT BASED ON MODEL
INDICATIONS AND MOS OUTPUT ANTICIPATE ONLY SCT AREAS OF MVFR WITH
VFR PREVAILING THIS EVENING.
SURFACE WINDS CLOSER TO THE RIDGE AXIS UPSTREAM PRETTY UNIFORMLY
OUT OF THE NE AND AOB 10KT. WINDS AT LOCAL TERMINALS TO BACK
DURING THE FIRST PART OF THE EVENING BOTH DIURNALLY AND AS RIDGE
AXIS NEARS OVERHEAD...WITH WINDS TURNING TO OUT OF THE W TO WSW
BY MIDNIGHT AS THE RIDGE AXIS SLIPS S OF THE TERMINALS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN CIG TRENDS THRU THIS EVE.
* LOW CONFIDENCE IN LAKE EFFECT SHOWERS IMPACTING CHI TERMINALS
MID AFTERNOON-EARLY EVENING.
* MEDIUM CONFIDENCE IN WIND FORECASTS THROUGH THIS EVE.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT AND THURSDAY...VFR
* THURSDAY NIGHT...CHANCE OF LIGHT SNOW. MVFR POSSIBLE
* FRIDAY THROUGH MONDAY...VFR
SHEA
&&
.MARINE...
158 PM CST
A SURFACE RIDGE OF HIGH PRESSURE EXTENDING FROM THE PLAINS
NORTHEASTWARD ACROSS THE UPPER GREAT LAKES REGION WILL SLOWLY SAG
SOUTHWARD TONIGHT AS A STRONG AREA OF LOW PRESSURE MOVES INTO
THE HUDSON BAY. AS THIS SURFACE RIDGE MOVES ACROSS LAKE MICHIGAN
THERE WILL BE A PERIOD OF LIGHTER WINDS THIS EVENING. HOWEVER...THIS
WILL BE SHORT LIVED AS THE WINDS WILL BECOME WEST SOUTHWESTERLY AND
INCREASE TO NEAR 30 KT LATER TONIGHT ACROSS THE NORTHERN HALF OF THE
LAKE. THESE WINDS WILL CONTINUE LAKE-WIDE DURING THE DAY ON
WEDNESDAY AS A COLD FRONT MOVES SOUTH ACROSS THE LAKE. THERE COULD
BE A PERIOD OF LOW END GALES AS THE COLD AIR BEGINS TO PUSH ACROSS
THE LAKE WEDNESDAY NIGHT INTO THURSDAY. HOWEVER...WIDESPREAD 30 KT
WITH SOME GALE FORCE GUSTS APPEARS TO BE THE MOST LIKELY AT THIS
TIME.
WINDS ACROSS LAKE MICHIGAN LOOK TO REMAIN IN THE 15 TO 25 KT RANGE
INTO FRIDAY AS THE PRESSURE GRADIENT BETWEEN THE LOW ACROSS THE
HUDSON BAY AND HIGH PRESSURE ACROSS THE PLAINS REMAINS ELEVATED.
ANOTHER SURGE OF HIGHER WINDS...POTENTIALLY GALE FORCE...LOOKS TO
OCCUR ON SATURDAY AS ANOTHER AREA OF LOW PRESSURE TRACKS ACROSS
SOUTHERN CANADA.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1153 AM CST TUE DEC 6 2011
.DISCUSSION...
304 AM CST
FORECAST HIGHLIGHTS TODAY INCLUDE LAKE EFFECT PRECIP TODAY...CLOUD
TRENDS THROUGH TONIGHT...POTENTIAL LIGHT SNOW EVENT THURSDAY NIGHT
PRIOR TO THE ARRIVAL OF SEASONS COLDEST AIR MASS LATE IN THE WEEK.
VERY LITTLE CHANGE IS EXPECTED TO WINDS/STABILITY OVER THE LAKE
THROUGH MIDDAY...SO GENERALLY EXPECTING A CONTINUATION OF LIGHT
NUISANCE TYPE LAKE EFFECT RAIN/SNOW SHOWERS THROUGH THIS MORNING
OVER NORTHEAST ILLINOIS. P-TYPE SHOULD BE MOSTLY RAIN NEAR THE LAKE
WITH GREATER THREAT OF SNOW MIXTURE INLAND. EVEN WHERE PRECIP
CHANGES TO ALL SNOW TEMPS SHOULD MOSTLY BE TOO WARM TO ALLOW FOR
ANYTHING MORE THAN A BRIEF DUSTING AT WORST. WINDS WILL BEGIN
BACKING THIS AFTERNOON SENDING THE SCATTERED LIGHT LAKE EFFECT
PRECIP EASTWARD MORE INTO NW INDY THIS AFTERNOON BEFORE MOVING EAST
AND OUT OF OUR CWA TOWARD EVENING.
REGARDING CLOUDINESS TODAY...TIS THE SEASON FOR STRATUS AS EVENING
RAOBS ACROSS THE REGION SHOWED A RATHER TEXT BOOK STRATUS SOUNDING
WITH MOISTURE BENEATH A SHARP FRONTAL INVERSION. HAVE SEEN SOME
BREAKS IN THE STRATUS OVER IN EASTERN WI AND COULD SEE A FEW HOLES
FROM TODAY OVER MAINLY NE IL...BUT AS FLOW BACKS TO THE NORTHWEST
WOULD ANTICIPATE THE STRATUS DECK TO OUR WEST TO ADVECT EASTWARD
AND KEEP US FAIRLY SOCKED IN THROUGH TODAY AND INTO THIS EVENING.
HAVE OPTED TO GO SOMEWHAT OPTIMISTIC WITH CLEARING TONIGHT FROM
THE WEST...AND HANG ONTO CLOUDS LONGER THAN ANY GUIDANCE WOULD
SUGGEST AS MODELS ARE NOTORIOUS FOR STRUGGLING WITH SHALLOW COOL
SEASON STRATUS. GIVEN THE EXPECTATION OF CLOUD COVER HAVE GONE
AHEAD AND RAISED LOW TEMPS TONIGHT...PARTICULARLY SOUTHEAST CWA.
STRONG SHORTWAVE PASSES WELL TO OUR SOUTH WEDNESDAY AS LONG WAVE
TROUGH RELOADS TO OUR NORTHWEST AND IS PREPARED TO TAKE AN ARCTIC
DUMP ON US LATER THIS WEEK. PROBABLY THE MOST CONTENTIOUS PART OF
THE FORECAST REVOLVES AROUND THE POTENTIAL FOR SOME ACCUMULATING
SNOW THURSDAY NIGHT. GLOBAL MODELS ALL GENERALLY AGREE ON
DEVELOPING A TIGHTENING LOW/MID LEVEL BAROCLINIC ZONE IN ADVANCE
OF VIGOROUS SHORTWAVE MOVING INTO THE WESTERN GREAT LAKES REGION
THURSDAY NIGHT. MODELS CONTINUE TO HINT AT THE DEVELOPMENT OF BAND
OF LIGHT FRONTOGENTICALLY DRIVEN PRECIP IN ADVANCE OF THIS
SHORTWAVE WHICH COULD BE ENOUGH TO PRODUCE A NARROW BAND OF AN
INCH OR SO OF SNOW. THE DEVIL IS IN THE DETAILS HOWEVER AS THE
AREA TO SEE THAT SNOWFALL WOULD LIKELY TO BE FAIRLY SMALL AND
MODELS HAVE BEEN BOUNCING AROUND A BIT WITH RESPECT TO THE
PLACEMENT OF THE HEAVIEST (ALBEIT STILL LIGHT) PRECIP. THE WRF-NMM
AND WRF-ARW SUGGEST MOISTURE WILL BE TOO LIMITED AND FORCING TOO
FAR SOUTH TO SERIOUSLY THREATEN OUR CWA WITH SUPPORT FROM THE
CANADIAN MODEL. HAVING SAID ALL OF THIS...IT REALLY EQUATES TO
LITTLE CHANGE FROM PREVIOUS FORECAST WITH SLIGHT CHANCE TO LOW END
CHANCE POPS ACROSS THE CWA THURSDAY NIGHT.
CWA WILL THEN GET SIDE-SWIPED BY A BITTERLY COLD EARLY SEASON SHOT
OF ARCTIC AIR FRIDAY INTO FRIDAY NIGHT WITH H8 TEMPS PROGGED TO DROP
TO -15C OR COLDER. TEMPS FRIDAY LOOK TO BE FAIRLY STEADY AND MAY
EVEN FALL A BIT AS HEART OF ARCTIC AIR ARRIVES. SAVING GRACE WITH
THIS COLD SNAP IS THE LACK OF SNOW COVER HERE AND UPSTREAM LIKELY
ALLOWING IT TO MODIFY SOMEWHAT. EVEN SO TEMPS IN THE 20 LOOK LIKELY
FRIDAY WITH LOWS IN THE TEENS FRIDAY NIGHT AWAY FROM THE CITY.
PATTERN PROGGED TO REMAIN VERY PROGRESSIVE WITH BITTER COLD GETTING
SHOVED QUICKLY EASTWARD OVER THE WEEKEND AS A UPPER FLOW TRANSITIONS
TO MORE ZONAL. INCREASINGLY STRONG SOUTHWESTERLY WINDS SHOULD SEND
TEMPS BACK TO NEAR IF NOT ABOVE NORMAL BY SUNDAY INTO MONDAY WITH
LITTLE TO NO THREAT OF ANY PRECIP FRIDAY AFTERNOON THROUGH MONDAY.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* POTENTIAL LAKE EFFECT SNOW SHOWERS EARLY-MID AFTERNOON.
* LIGHT SNOW APPROACHING FROM THE SW.
* VARIABLE VFR/MVFR CIGS INTO THIS EVENING.
TRS
//DISCUSSION...UPDATED 18Z...
AREA OF RADAR ECHOES CONTINUES TO MOVE NORTHEASTWARD OVER N
CENTRAL IL AND APPROACHING METRO NE IL. LIGHT SNOW HAS BEEN
REPORTED AT DVN...MLI...GBG...PIA...C75 WHERE SURFACE DEW POINT
DEPRESSIONS ONLY 1 TO 3 DEG F. WITH MODELS DAMPENING OUT THE
SHORT WAVE FORCING THIS -SN AS IT CONTINUES NORTHEASTWARD FROM NW
MO...SE IA...W CENTRAL IL THIS AFTERNOON AND AN INCREASINGLY
ANTICYCLONIC LOW LEVEL FLOW AS THE SURFACE RIDGE CONTINUES TO
BUILD SOUTHEASTWARD FROM THE UPPER MIDWEST AND MID MO
VALLEY...ALONG WITH MUCH DRIER LOW LEVEL AIR WITH DEW POINTS ONLY
IN THE TEENS TO LOWER 20S F ACROSS NORTHERN IL DO NOT ANTICIPATE
ANY OF THIS PRECIP TO REACH THE GROUND AT THE LOCAL TERMINALS.
TRAJECTORY OF COLD AIR DOWN LAKE MI HAS POTENTIAL TO BRING LAKE
EFFECT SNOW SHOWERS TO NE IL THIS AFTERNOON. VISIBLE SATELLITE
LOOP SHOWING A LAKE EFFECT BAND HAS SPREAD SOUTHWARD FROM E OF
MTW TO E OF ETB LAST COUPLE HOURS. LATEST RUNS OF RUC13 CONTINUE
TO BRING LIGHT PRECIP TO THE IL SHORE 1BETWEEN 18Z AND 19Z. OTHER
HIGH RESOLUTION MODELS LESS AGGRESSIVE AND ONLY SPIT OUT SPOTTY
0.01 QPF AMOUNTS OVER THE WATER. TEMPERATURE INVERSION PER
FORECAST TEMPERATURE PROFILES AND VERIFIED BY ACARS DATA SHOW BASE
TO BE LOCATED BETWEEN 050 AND 060 AGL WHICH WOULD BE DEEP ENOUGH
FOR SOME LIGHT LAKE EFFECT THOUGH AS MENTIONED ABOVE LOW LEVEL
FLOW BECOMES MORE ANTICYCLONIC WITH TIME THIS AFTERNOON AND DRY
AIR IN PLACE OVER FAR NE IL AND UPSTREAM. RAC HAS HAD A PERSISTENT
NNE WIND OFF THE LAKE ALL MORNING AND DEW POINT THERE HELD AT ONLY
22Z UNTIL 17Z WHEN IT DROPPED TO 20F. A LOW CHANCE OF SOME LAKE
EFFECT SHOWERS REACHING VC ORD AND/OR MDW STILL EXISTS SO HAVE
KEPT MENTION OF VCSH THESE SITES 20Z-23Z.
REGARDING CEILINGS THIS AFTERNOON...METARS FROM NEAR THE SE WI
AND NE IL SHORES SHOW THEM CONTINUING TO HOVER AROUND 030.
EXPECT AT LEAST AREAS OF CIGS AROUND 030 THESE AREAS UNTIL FLOW
AT CLOUD LEVEL BACKS TO N AND NW LATER AFTERNOON AND THIS EVENING.
A PERSISTENT AREA OF MVFR STRATUS/STRATOCU HAS BEEN IN PLACE OVER
NW WI...FARR SE MN...EASTERN IA...AND NE THROUGH SOUTHERN MO AHEAD
OF THE SURFACE RIDGE AXIS. EXPECT THESE CLOUDS TO SHIFT E TO SE AS
DOES THE RIDGE DURING THE AFTERNOON AND EVENING BUT BASED ON MODEL
INDICATIONS AND MOS OUTPUT ANTICIPATE ONLY SCT AREAS OF MVFR WITH
VFR PREVAILING THIS EVENING.
SURFACE WINDS CLOSER TO THE RIDGE AXIS UPSTREAM PRETTY UNIFORMLY
OUT OF THE NE AND AOB 10KT. WINDS AT LOCAL TERMINALS TO BACK
DURING THE FIRST PART OF THE EVENING BOTH DIURNALLY AND AS RIDGE
AXIS NEARS OVERHEAD...WITH WINDS TURNING TO OUT OF THE W TO WSW
BY MIDNIGHT AS THE RIDGE AXIS SLIPS S OF THE TERMINALS.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN CIG TRENDS THRU THIS EVE.
* LOW CONFIDENCE IN LAKE EFFECT SHOWERS IMPACTING CHI TERMINALS
MID AFTERNOON-EARLY EVENING.
* MEDIUM CONFIDENCE IN WIND FORECASTS THROUGH THIS EVE.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT AND THURSDAY...VFR
* THURSDAY NIGHT...CHANCE OF LIGHT SNOW. MVFR POSSIBLE
* FRIDAY THROUGH MONDAY...VFR
SHEA
&&
.MARINE...
248 AM CST
HIGH PRESSURE EXTENDING FROM THE UPPER MISSISSIPPI VALLEY THROUGH
THE CENTRAL PLAINS WILL SLOWLY SAG ACROSS THE GREAT LAKES REGION
TODAY AND TONIGHT AS A STRONG LOW PRESSURE SYSTEM MOVES ACROSS
NORTHERN MANITOBA INTO THE HUDSON BAY. THIS LOW WILL DRAG A COLD
FRONT ACROSS LAKE MICHIGAN WEDNESDAY. DURING THIS PERIOD...WINDS
OVER THE LAKE WILL GRADUALLY SHIFT FROM NORTHERLY TO SOUTHWESTERLY.
WIND SPEEDS WILL DIMINISH TO AS LOW AS TO TO 15 KT LATE TONIGHT AS
THE SFC RIDGE AXIS CROSSES THE LAKE...BUT AS THE RIDGE PUSHES TO THE
SOUTH AND A SFC TROUGH ASSOCIATED WITH THE COLD FRONT DROPS THROUGH
THE NORTHERN PLAINS LATE TONIGHT...WINDS WILL QUICKLY INCREASE AGAIN
TO AROUND 30 KT. FOLLOWING THE PASSAGE OF THE COLD FRONT...ANOTHER
CANADIAN HIGH PRESSURE SYSTEM WILL DROP SOUTHEAST ACROSS THE PLAINS
THURSDAY AND FRIDAY. THIS SHOULD MAINTAIN A MODERATE PRESSURE
GRADIENT OVER THE GREAT LAKES. THE COMBINATION OF THE MODERATELY
STRONG PRESSURE GRADIENT AND STRONG COLD ADVECTION BEHIND THE
EXITING FRONT WILL KEEP WINDS AROUND 25 TO 30KT OVER THE LAKE FROM
WEDNESDAY THROUGH SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1105 AM CST TUE DEC 6 2011
.DISCUSSION...
304 AM CST
FORECAST HIGHLIGHTS TODAY INCLUDE LAKE EFFECT PRECIP TODAY...CLOUD
TRENDS THROUGH TONIGHT...POTENTIAL LIGHT SNOW EVENT THURSDAY NIGHT
PRIOR TO THE ARRIVAL OF SEASONS COLDEST AIR MASS LATE IN THE WEEK.
VERY LITTLE CHANGE IS EXPECTED TO WINDS/STABILITY OVER THE LAKE
THROUGH MIDDAY...SO GENERALLY EXPECTING A CONTINUATION OF LIGHT
NUISANCE TYPE LAKE EFFECT RAIN/SNOW SHOWERS THROUGH THIS MORNING
OVER NORTHEAST ILLINOIS. P-TYPE SHOULD BE MOSTLY RAIN NEAR THE LAKE
WITH GREATER THREAT OF SNOW MIXTURE INLAND. EVEN WHERE PRECIP
CHANGES TO ALL SNOW TEMPS SHOULD MOSTLY BE TOO WARM TO ALLOW FOR
ANYTHING MORE THAN A BRIEF DUSTING AT WORST. WINDS WILL BEGIN
BACKING THIS AFTERNOON SENDING THE SCATTERED LIGHT LAKE EFFECT
PRECIP EASTWARD MORE INTO NW INDY THIS AFTERNOON BEFORE MOVING EAST
AND OUT OF OUR CWA TOWARD EVENING.
REGARDING CLOUDINESS TODAY...TIS THE SEASON FOR STRATUS AS EVENING
RAOBS ACROSS THE REGION SHOWED A RATHER TEXT BOOK STRATUS SOUNDING
WITH MOISTURE BENEATH A SHARP FRONTAL INVERSION. HAVE SEEN SOME
BREAKS IN THE STRATUS OVER IN EASTERN WI AND COULD SEE A FEW HOLES
FROM TODAY OVER MAINLY NE IL...BUT AS FLOW BACKS TO THE NORTHWEST
WOULD ANTICIPATE THE STRATUS DECK TO OUR WEST TO ADVECT EASTWARD
AND KEEP US FAIRLY SOCKED IN THROUGH TODAY AND INTO THIS EVENING.
HAVE OPTED TO GO SOMEWHAT OPTIMISTIC WITH CLEARING TONIGHT FROM
THE WEST...AND HANG ONTO CLOUDS LONGER THAN ANY GUIDANCE WOULD
SUGGEST AS MODELS ARE NOTORIOUS FOR STRUGGLING WITH SHALLOW COOL
SEASON STRATUS. GIVEN THE EXPECTATION OF CLOUD COVER HAVE GONE
AHEAD AND RAISED LOW TEMPS TONIGHT...PARTICULARLY SOUTHEAST CWA.
STRONG SHORTWAVE PASSES WELL TO OUR SOUTH WEDNESDAY AS LONG WAVE
TROUGH RELOADS TO OUR NORTHWEST AND IS PREPARED TO TAKE AN ARCTIC
DUMP ON US LATER THIS WEEK. PROBABLY THE MOST CONTENTIOUS PART OF
THE FORECAST REVOLVES AROUND THE POTENTIAL FOR SOME ACCUMULATING
SNOW THURSDAY NIGHT. GLOBAL MODELS ALL GENERALLY AGREE ON
DEVELOPING A TIGHTENING LOW/MID LEVEL BAROCLINIC ZONE IN ADVANCE
OF VIGOROUS SHORTWAVE MOVING INTO THE WESTERN GREAT LAKES REGION
THURSDAY NIGHT. MODELS CONTINUE TO HINT AT THE DEVELOPMENT OF BAND
OF LIGHT FRONTOGENTICALLY DRIVEN PRECIP IN ADVANCE OF THIS
SHORTWAVE WHICH COULD BE ENOUGH TO PRODUCE A NARROW BAND OF AN
INCH OR SO OF SNOW. THE DEVIL IS IN THE DETAILS HOWEVER AS THE
AREA TO SEE THAT SNOWFALL WOULD LIKELY TO BE FAIRLY SMALL AND
MODELS HAVE BEEN BOUNCING AROUND A BIT WITH RESPECT TO THE
PLACEMENT OF THE HEAVIEST (ALBEIT STILL LIGHT) PRECIP. THE WRF-NMM
AND WRF-ARW SUGGEST MOISTURE WILL BE TOO LIMITED AND FORCING TOO
FAR SOUTH TO SERIOUSLY THREATEN OUR CWA WITH SUPPORT FROM THE
CANADIAN MODEL. HAVING SAID ALL OF THIS...IT REALLY EQUATES TO
LITTLE CHANGE FROM PREVIOUS FORECAST WITH SLIGHT CHANCE TO LOW END
CHANCE POPS ACROSS THE CWA THURSDAY NIGHT.
CWA WILL THEN GET SIDE-SWIPED BY A BITTERLY COLD EARLY SEASON SHOT
OF ARCTIC AIR FRIDAY INTO FRIDAY NIGHT WITH H8 TEMPS PROGGED TO DROP
TO -15C OR COLDER. TEMPS FRIDAY LOOK TO BE FAIRLY STEADY AND MAY
EVEN FALL A BIT AS HEART OF ARCTIC AIR ARRIVES. SAVING GRACE WITH
THIS COLD SNAP IS THE LACK OF SNOW COVER HERE AND UPSTREAM LIKELY
ALLOWING IT TO MODIFY SOMEWHAT. EVEN SO TEMPS IN THE 20 LOOK LIKELY
FRIDAY WITH LOWS IN THE TEENS FRIDAY NIGHT AWAY FROM THE CITY.
PATTERN PROGGED TO REMAIN VERY PROGRESSIVE WITH BITTER COLD GETTING
SHOVED QUICKLY EASTWARD OVER THE WEEKEND AS A UPPER FLOW TRANSITIONS
TO MORE ZONAL. INCREASINGLY STRONG SOUTHWESTERLY WINDS SHOULD SEND
TEMPS BACK TO NEAR IF NOT ABOVE NORMAL BY SUNDAY INTO MONDAY WITH
LITTLE TO NO THREAT OF ANY PRECIP FRIDAY AFTERNOON THROUGH MONDAY.
IZZI
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* POTENTIAL LAKE EFFECT SNOW SHOWERS EARLY-MID AFTERNOON.
* LIGHT SNOW APPROACHING FROM THE SW.
* VARIABLE VFR/MVFR CIGS INTO THIS EVENING.
TRS
//DISCUSSION...UPDATED 16Z...
AREA OF RADAR ECHOES CONTINUES TO MOVE NORTHEASTWARD OVER N
CENTRAL IL AND APPROACHING METRO NE IL. LIGHT SNOW HAS BEEN
REPORTED AT DVN...MLI...PIA...C75 WHERE SURFACE DEW POINT
DEPRESSIONS 1-3 DEG F. WITH MODELS DAMPENING OUT THE SHORT WAVE
FORCING THIS -SN THIS AFTERNOON AS IT CONTINUES NORTHEASTWARD
FROM NW MO AND SE IA...INCREASINGLY ANTICYCLONIC LOW LEVEL FLOW
AS THE SURFACE RIDGE CONTINUES TO BUILD SOUTHEASTWARD FROM THE
UPPER MIDWEST AND MID MO VALLEY...AND WITH MUCH DRIER LOW LEVEL
AIR WITH DEW POINTS ONLY IN THE TEENS TO LOWER 20S F ACROSS
NORTHERN IL DO NOT ANTICIPATE ANY OF THIS PRECIP TO REACH THE
GROUND AT THE LOCAL TERMINALS.
TRAJECTORY OF COLD AIR DOWN LAKE MI HAS POTENTIAL TO BRING LAKE
EFFECT SNOW SHOWERS TO NE IL THIS AFTERNOON. VISIBLY SATELLITE
LOOP SHOWING A LAKE EFFECT BAND HAS SPREAD SOUTHWARD FROM E OF
MTW TO E OF ETB LAST COUPLE HOURS. LATEST RUNS OF RUC13 CONTINUE
TO BRING LIGHT PRECIP TO THE IL SHORE AROUND 19Z. OTHER HIGH
RESOLUTION MODELS LESS AGGRESSIVE AND ONLY SPIT OUT SPOTTY 0.01 QPF
AMOUNTS OVER THE WATER. BASE OF INVERSION PER FORECAST
TEMPERATURE PROFILES AND VERIFIED BY ACARS DATA SHOW IT TO BE
LOCATED 5500-6000 FT AGL WHICH WOULD DEEP ENOUGH FOR SOME LIGHT
LAKE EFFECT THOUGH AS MENTIONED ABOVE LOW LEVEL FLOW BECOMES MORE
ANTICYCLONIC WITH TIME THIS AFTERNOON AND DRY AIR IN PLACE OVER
FAR NE IL AND UPSTREAM. RAC HAS HAD A PERSISTENT NNE WIND OFF THE
LAKE ALL MORNING AND DEW POINT THERE STILL ONLY 22F. A LOW CHANCE
OF SOME LAKE EFFECT SHOWERS REACHING VC ORD AND/OR MDW STILL
EXISTS SO HAVE KEPT MENTION OF VCSH THESE SITES 18Z-21Z.
REGARDING CEILINGS LATE MORNING THROUGH AFTERNOON...METARS FROM
NEAR THE SE WI AND NE IL SHORES HOVER AROUND 030. EXPECT AT LEAST
AREAS OF CIGS AROUND 030 THESE AREAS UNTIL FLOW AT CLOUD LEVEL
BACKS TO N TO NW. A PERSISTENT AREA OF MVFR STRATUS/STRATOCU
HAS BEEN IN PLACE AHEAD OF THE SURFACE RIDGE AXIS. EXPECT THESE
CLOUDS TO SHIFT E TO SE AS DOES THE RIDGE THIS AFTERNOON AND
EVENING BUT BASED ON MODEL INDICATIONS AND MOS OUTPUT ANTICIPATE
ONLY PREVAILING SCT AREAS OF MVFR THIS EVENING.
SLIGHT BACKING OF WINDS AT ORD AND MDW LAST HOUR OR TWO LIKELY IN
RESPONSE TO INCREASING CONVERGENT BAND MOVING DOWN FROM MID LAKE
SO HAVE KEPT WITH THIS NOTION THROUGH THE AFTERNOON AND THEN
FURTHER BACKING DUE TO APPROACHING SURFACE RIDGE OCCURS THIS
EVE.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE IN CIG TRENDS INTO THIS EVE.
* LOW CONFIDENCE IN LAKE EFFECT SHOWERS IMPACTING CHI TERMINALS
THIS AFTERNOON.
* MEDIUM CONFIDENCE IN WIND FORECASTS INTO THIS EVE.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT AND THURSDAY...VFR
* THURSDAY NIGHT...CHANCE OF LIGHT SNOW. MVFR POSSIBLE
* FRIDAY THROUGH MONDAY...VFR
SHEA
&&
.MARINE...
248 AM CST
HIGH PRESSURE EXTENDING FROM THE UPPER MISSISSIPPI VALLEY THROUGH
THE CENTRAL PLAINS WILL SLOWLY SAG ACROSS THE GREAT LAKES REGION
TODAY AND TONIGHT AS A STRONG LOW PRESSURE SYSTEM MOVES ACROSS
NORTHERN MANITOBA INTO THE HUDSON BAY. THIS LOW WILL DRAG A COLD
FRONT ACROSS LAKE MICHIGAN WEDNESDAY. DURING THIS PERIOD...WINDS
OVER THE LAKE WILL GRADUALLY SHIFT FROM NORTHERLY TO SOUTHWESTERLY.
WIND SPEEDS WILL DIMINISH TO AS LOW AS TO TO 15 KT LATE TONIGHT AS
THE SFC RIDGE AXIS CROSSES THE LAKE...BUT AS THE RIDGE PUSHES TO THE
SOUTH AND A SFC TROUGH ASSOCIATED WITH THE COLD FRONT DROPS THROUGH
THE NORTHERN PLAINS LATE TONIGHT...WINDS WILL QUICKLY INCREASE AGAIN
TO AROUND 30 KT. FOLLOWING THE PASSAGE OF THE COLD FRONT...ANOTHER
CANADIAN HIGH PRESSURE SYSTEM WILL DROP SOUTHEAST ACROSS THE PLAINS
THURSDAY AND FRIDAY. THIS SHOULD MAINTAIN A MODERATE PRESSURE
GRADIENT OVER THE GREAT LAKES. THE COMBINATION OF THE MODERATELY
STRONG PRESSURE GRADIENT AND STRONG COLD ADVECTION BEHIND THE
EXITING FRONT WILL KEEP WINDS AROUND 25 TO 30KT OVER THE LAKE FROM
WEDNESDAY THROUGH SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
249 AM CST TUE DEC 6 2011
.DISCUSSION...
852 PM CST
A FEW CHALLENGES REVOLVING AROUND THE LAKE EFFECT PRECIPITATION
THIS EVENING. RADAR IMAGERY SHOWS PRECIPITATION FROM MILWAUKEE
SOUTH INTO NORTHERN WILL COUNTY. WATER VAPOR IMAGERY SHOWS
DEFORMATION ZONE MOVING EAST OF THE FORECAST AREA WITH SUBSIDENCE
AND MID LEVEL DRY AIR MOVING IN FROM THE SOUTHWEST. HAVE SEEN
OVERALL INTENSITY OF RETURNS OFF THE LAKE DECREASE SOMEWHAT AS
THIS FEATURE PROGRESSES THROUGH...BUT FORECAST SOUNDINGS SHOW
LITTLE CHANGE IN THE LOW AND MID LEVELS OVERNIGHT AND SUSPECT AREA
OF PRECIPITATION WILL CONTINUE THROUGH THE REMAINDER OF THE
EVENING AND OVERNIGHT. SOUNDINGS DO SHOW A SLIGHT DECREASE IN THE
INVERSION HEIGHTS BETWEEN 06-09Z...AND MOST OF THE HIGH-RES
GUIDANCE...WITH THE RUC BEING THE EXCEPTION...SHOWS PRECIP
DIMINISHING LATE TONIGHT. SUSPECT THE RUC MAY BE ONTO SOMETHING
THOUGH...WITH NO REAL SENSE OF WHAT MAY CAUSE LAKE EFFECT TO SHUT
OFF OVERNIGHT...THUS WILL BUMP UP POPS FOR TONIGHT.
PRECIP TYPE ALSO A BIG QUESTION MARK. THE 129DM LINE ON THE
1000-850MB THICKNESS LINES UP WELL WITH CURRENT RAIN-SNOW LINE AND
DOES GRADUALLY SHIFT SOUTH THROUGH COOK COUNTY TONIGHT...BUT
LOCALIZED EFFECTS WITH WARM AIR OFF THE LAKE AND URBAN HEAT ISLAND
WILL DELAY THE CHANGE OVER TO SNOW FOR AREAS ALONG THE LAKESHORE AND
PORTIONS OF COOK COUNTY DESPITE THE GRADUAL COOL ADVECTION.
HOWEVER...WET-BULBING EFFECTS UNDER THE HEAVIER SHOWERS MAY
DOMINATE...AND HAS ALREADY BEEN EVIDENT ON DUAL-POL IMAGERY WITH
SOME OF THE SHOWERS THAT PASSED OVER SOUTHERN DUPAGE COUNTY EARLIER
TONIGHT WHERE SNOW BRIEFLY MADE ITS WAY TO THE SURFACE. SO DO EXPECT
A CHANGE OVER TO SNOW AT SOME POINT...BUT HAVE VERY LOW CONFIDENCE
ON PRECISE TIMING. PRECIP AMOUNT REPORTS HAVE BEEN ON THE ORDER OF A
FEW HUNDREDTHS THUS FAR UNDER THE STRONGEST RETURNS...AND SEE NO
REASON FOR THIS TO CHANGE OVERNIGHT NOR HAVE ANY CONCERNS FOR
ACCUMULATIONS. FORECAST UPDATES TO FOLLOW SHORTLY...BMD
//PREV DISCUSSION...
NEAR TERM....THIS AFTERNOON THROUGH TONIGHT...
VISIBLE IMAGERY CONTINUES TO SHOW A THICK STRATUS LAYER OVERHEAD.
VERTICAL GROWTH OF THE CLOUD DESK REMAINS WELL SOUTH OF THE REGION
OVER THE OZARKS AND WESTERN TENNESSEE. WITH THE ABUNDANT SOLAR
SHIELDING...TEMPERATURES THIS AFTERNOON HAVE NOT WARMED MUCH. THUS
EXPECT TEMPS TO REMAIN IN THE MID/UPR 30S. BETTER COLD AIR ADVECTION
HAS CONTINUED TO OCCUR ACROSS WEST CENTRAL ILLINOIS WHERE
TEMPERATURES HAVE HELD AROUND 30...AND IN THE MID 20S ACROSS CENTRAL
MISSOURI. IR IMAGERY THIS AFTERNOON ALSO CONTINUES TO INDICATE MUCH
THICKER CLOUD COVER OVER ILLINOIS/INDIANA.
WSR-88D RADAR WAS DEPICTING PRECIPITATION PUSHING INLAND ACROSS BOTH
COOK AND LAKE COUNTY ILLINOIS...AS LAKE MOISTURE SLOWLY SLIDES
SOUTH/SOUTHWEST. MOISTURE REMAINS VERY SHALLOW AND MINIMAL
LIFT...SUPPORTING PRECIP TO REMAIN AS LIQUID WITH PATCHY DRIZZLE.
FURTHER NORTH A FEW OBSERVATIONS ACROSS WISCONSIN HAVE REPORTED LGT
SN. FOR FAR NORTHEAST ILLINOIS TEMPERATURES ARE WARM ENOUGH TO
MAINTAIN A LIQUID STATE OF PRECIPITATION. QUASI-STATIONARY BOUNDARY
REMAINS TO OUR SOUTHEAST ACROSS THE OZARKS STRETCHING NORTHEAST
THROUGH THE OHIO VALLEY.
OVERNIGHT THE CHALLENGE WILL CONTINUE TO BE COVERAGE OF PRECIP...AND
TEMPERATURES. GUIDANCE HAS SUGGESTED THAT TEMPERATURES WILL COOL
MORE EFFICIENTLY TONIGHT WITH BETTER COLD AIR ADVECTION INTO
NORTHERN IL/NORTHWEST IN...HOWEVER FEEL THIS IS TOO OVERDONE. THUS
HAVE ADJUSTED OVERNIGHT LOWS UP A FEW DEGREES GIVEN THE EXPECTED
THICK CLOUD COVER. WINDS START TO TURN NORTHEASTERLY THIS EVENING
AND CONTINUE OVERNIGHT...WHICH SHOULD AID IN BENDING THE LAKE
MOISTURE SOUTHWEST OR OVER NORTHEAST ILLINOIS. THUS HAVE MAINTAINED
MENTION OF SLIGHT CHANCE WORDING.
VERTICAL LIFT APPEARS TO BUMP UP A TAD OVERNIGHT...WITH SFC TEMPS
PUSHING CLOSER TO FREEZING. MODEL SOUNDINGS INDICATE THAT ANY PRECIP
THAT FALLS THIS EVENING WOULD START AS LIQUID...THEN POSSIBLY START
TO MIX WITH LGT SNOW. AS PREVIOUSLY MENTIONED ABOUT THE MINIMAL
LIFTING MECHANISM...IT IS POSSIBLE THAT PATCHY DRIZZLE COULD OCCUR
BEFORE LGT SNOW WOULD OCCUR.
QPF REMAINS MINIMAL...OR LESS THAN 0.05 THROUGH THE NEXT 24HRS. MORE
THAN LIKELY IT IS CLOSER TO 0.01 TO 0.03. BASED ON THE EXPECTED
TEMPERATURES AND MINIMAL LIFT...ANY SNOW THAT DOES FALL MAY
ACCUMULATE UP TO A QUARTER OF AN INCH. ALTHOUGH THAT BEING
SAID...CONFIDENCE IS LOW THAT THIS SCENARIO WOULD PAN OUT.
TUESDAY THROUGH THURSDAY...
A WEAK WAVE IS PROGGED TO DEVELOP ALONG THE QUASI-STATIONARY
BOUNDARY AND SLIDE NORTHEAST THROUGH MISSOURI. ANTI-CYCLONIC FLOW
REMAINS UPSTREAM ACROSS IOWA/MINNESOTA/WISCONSIN...WHICH SHOULD
START TO TURN OFF LAKE MOISTURE SOMETIME TUE AFTN/EVE. HAVE HELD
ONTO MENTION OF LGT RA/SN THRU THE MORNING HOURS. AFTN TEMPS SHOULD
WARM MARGINALLY TO AROUND THE MID 30S ACROSS MOST OF THE CWFA. BY
TUE AFTN/EVE THE INFLUENCE FROM THE UPSTREAM RIDGE SHOULD FINALLY
ERODE THE THICK STRATUS AND ALLOW PARTLY CLOUD SKIES TO DEVELOP BY
THE LATE AFTN/EVE. THIS COUPLED WITH 850MB THERMAL TROUGH OF -10 TO
-12 DEG...WILL SET THE STAGE FOR OVERNIGHT LOWS IN THE TEENS TO
LOWER 20S.
AS WINDS SLOWLY SHIFT FROM THE NORTHWEST TO THE WEST/SOUTHWEST
WED...THE LAKE MOISTURE WILL BECOME ORIENTED OVER LOWER MICHIGAN.
500MB VORT SLOWLY SLIDES EAST ALONG THE SOUTHERN STREAM...WHILE THE
NORTHERN STREAM REMAINS IN PROGRESSIVE. THE FOCUS WED WILL CONTINUE
TO BE ON THE ARRIVAL OF A POTENT FRONTAL BOUNDARY...THAT IS COUPLED
WITH AN 850MB THERMAL TROUGH OF -20 TO -22 DEG C. THIS WILL PROVIDE
THE COOLEST AIR OF THE SEASON LATER IN THE WEEK TO NORTHERN
IL/NORTHWEST IN.
PRIOR TO THE ARRIVAL OF THIS AIRMASS...MOISTURE IS EXPECTED TO POOL
ALONG THE FRONT AS IT SLOWLY PUSHES SOUTHEAST ACROSS THE PLAINS
THURSDAY. GUIDANCE HAS FLUCTUATED ON HOW THIS FEATURE WILL
UNFOLD...AND IT REMAINS POSSIBLE THAT A WEAK WAVE WILL DEVELOP ALONG
THE LEE-SIDE OF THE 500MB TROUGH AXIS. THIS SCENARIO COULD RESULT IN
LGT SNOW OVERSPREADING NORTHERN IL/NORTHWEST IN THUR AFTN AS THE
POTENT THERMAL TROUGH ARRIVES ALOFT. TEMPS THUR WILL REMAIN IN THE
LOW/MID 30S.
BEACHLER
LONG TERM...THURSDAY NIGHT THROUGH MONDAY
MAIN CONCERNS IN THE EXTENDED PORTION OF THE FORECAST ARE LIGHT SNOW
POTENTIAL THURSDAY NIGHT INTO EARLY FRIDAY...FOLLOWED BY THE FIRST
BLAST OF ARCTIC AIR OF THE SEASON FOR FRIDAY INTO EARLY SATURDAY.
ON THURSDAY NIGHT...AS MENTIONED ABOVE...DIGGING H5 TROUGH WILL
SPAWN A WEAK SURFACE LOW WHICH WILL TRACK ACROSS NORTHERN GREAT
LAKES AND SEND AN ARCTIC FRONTAL BOUNDARY TOWARD AREA. MODELS HAVE
BEEN CONSISTENT IN SPITTING OUT A STRIPE OF VERY LIGHT QPF NEAR OR
OVER CWA IN RESPONSE TO THIS FEATURE. WITH NEGATIVE TEEN AIR AT
H85 BUILDING IN FROM THE NORTH BEHIND ARCTIC FRONT...SUSPECT WAVE
WILL RIDE ALONG LOW LEVEL BAROCLINIC ZONE. A PEEK AT GFS TIME
HEIGHT AT ORD FOR THURSDAY NIGHT PERIOD SHOWS SATURATION AND
ADEQUATE LIFT INTO -15C FAVORED SNOW GROWTH ZONE.
THEREFORE...DESPITE QPF ONLY IN THE HUNDREDTHS UP TO MAYBE A TENTH
OR SLIGHTLY MORE...WITH VERY COLD AIR MASS...SNOW WOULD BE HIGH
RATIO AND POSSIBLY RESULT IN FIRST WIDESPREAD LIGHT ACCUMULATING
SNOW OF THE SEASON FOR MANY (IF SCENARIO PANS OUT...POTENTIAL FOR
AN INCH OR TWO OF SNOW). FOR NOW...HAVE BUMPED UP POPS IN GRIDS TO
CHANCE ACROSS THE AREA GIVEN SOME UNCERTAINTY IN EXACTLY WHERE
BEST SNOW POTENTIAL WILL OCCUR. LIGHT SNOW MAY LINGER INTO EARLY
FRIDAY FOR EASTERN PORTION OF CWA BEFORE WAVE SHIFTS OFF TO THE
EAST.
THEREAFTER...ON FRIDAY...STRONG CAA WILL BE IN FULL FORCE WITH SHARP
THERMAL TROUGH ARRIVING OVERHEAD LATE IN THE DAY. OPERATIONAL MODELS
AND ENSEMBLES HAVE BACKED OFF EVER SO SLIGHTLY ON JUST HOW COLD
ARCTIC AIR MASS WILL BE...BUT -15C OR SO AT H85 AND -8 TO -10 AT H95
WILL BE PLENTY COLD. TEMPERATURES WILL STRUGGLE INTO THE MID TO
UPPER 20S FRIDAY AFTERNOON WITH A PERSISTENT WNW BREEZE LEADING TO
LOW WIND CHILL VALUES. AXIS OF ARCTIC HIGH WILL PASS CLOSEST ON
FRIDAY NIGHT...LEADING TO STRONG RADIATIONAL COOLING. IF MINOR SNOW
COVER IS PRESENT...LOW TO MID TEENS...UPPER TEENS IN DOWNTOWN
CHICAGO...IN GRIDS FOR LOW EARLY SATURDAY MORNING MIGHT BE A FEW
DEGREES TOO HIGH. SW FLOW...STEADY WARMING ALOFT AND LIKELY FULL
SUNSHINE ON SATURDAY WILL ALLOW FOR SOME RECOVERY FROM VERY COLD
START TO DAY...BUT SUSPECT IT WILL BE TOUGH TO MAKE UP A LOT OF
GROUND DUE TO LIMITED DAYLIGHT THIS TIME OF YEAR. THUS SHAVED OFF A
DEGREE FROM MODEL BLEND FOR MAX TEMPERATURES ON SATURDAY...YIELDING
HIGHS IN THE UPPER 20S TO AROUND 30 DEGREES. SUNDAY AND MONDAY LOOK
TO BE MAINLY DRY WITH TEMPERATURES RETURNING TO CLOSE TO SEASONAL
NORMS DUE TO SOUTHERLY FLOW AND CONTINUED WARMING OF THE COLUMN. A
FRONTAL BOUNDARY MAY DROP SOUTH THROUGH THE AREA LATE MONDAY...
BRINGING NEXT CHANCE FOR LIGHT PRECIP...BUT LARGE MODEL UNCERTAINTY
THIS FAR OUT PRECLUDES ANYTHING MORE THAN SLIGHT POPS FOR MONDAY
NIGHT.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* POTENTIAL FOR LAKE EFFECT RAIN/SNOW SHOWERS THROUGH THE
AFTERNOON
* PERIODS OF MVFR CIGS THROUGH TUESDAY EVENING.
SHEA
//DISCUSSION...UPDATED 06Z...
MAIN FORECAST CONCERN AND CHALLENGE REMAINS THE LAKE EFFECT RAIN/
SNOW SHOWERS. OVERALL INTENSITY HAS DIMINISHED SOME FROM EARLIER
THIS EVENING BUT STILL MANY SHOWERS FROM FAR SOUTHEAST WI INTO
NORTHEAST IL. COOLER AIR SLOWLY FILTERING IN FROM THE NORTH HAS
CHANGED PRECIP TO MAINLY SNOW ACROSS SOUTHEAST WI INTO FAR
NORTHEAST IL...AS WELL AS LOCATIONS FARTHER INLAND...SUCH AS DPA
WHERE TEMPS HAVE ALSO COOLED A FEW DEGREES. FORECAST SOUNDINGS
CONTINUE TO SHOW THE INVERSION HEIGHT LOWERING SOME THROUGH THE
OVERNIGHT HRS AND THIS SHOULD LIMIT THE COVERAGE AND INTENSITY OF
THE LAKE EFFECT SHOWERS OVERNIGHT. WHILE THERE WILL STILL LIKELY
BE PERIODS OF LIGHT RAIN AND/OR LIGHT SNOW...CONFIDENCE IN TRYING
TO TIME ANY OF THIS PRECIP IS VERY LOW. AND FOR THAT REASON...HAVE
GONE WITH A VICINITY MENTION...THOUGH LATER UPDATES FOR PREVAILING
OR TEMPO PRECIP MAY BE NEEDED. LITTLE CHANGE TO THE AIRMASS OR LOW
LEVEL PROFILES INTO TUESDAY AFTERNOON AND THERE COULD BE
ADDITIONAL LAKE EFFECT SHOWERS THROUGH SUNSET...PERHAPS AIDED BY
DIURNAL WARMING BY MID/LATE MORNING. CONFIDENCE VERY LOW HERE AS
WELL.
OUTSIDE OF PRECIP AREAS...CIGS HAVE GENERALLY LIFTED INTO LOW VFR
WITH A FEW PATCHES OF HIGH MVFR CIGS. EXPECT THIS OVERALL TREND TO
CONTINUE WITH MVFR POSSIBLE IN AREAS OF HEAVIER PRECIP. THOUGH AM
CONCERNED THAT THERE COULD BE ANOTHER PERIOD OF MVFR CIGS TUESDAY
AFTERNOON. WITH A RIDGE OF HIGH PRESSURE MOVING ACROSS THE AREA
TUESDAY NIGHT...ANY MVFR CIGS MAY GET TRAPPED BELOW THE INVERSION
AND COULD PERSIST WELL INTO TUESDAY NIGHT.
NORTHEAST WINDS WILL SLOWLY TURN MORE NORTHERLY TUESDAY AFTERNOON
THEN SHOULD FLOP WESTERLY TUESDAY EVENING AS THE ABOVE MENTIONED
RIDGE BUILDS ACROSS THE AREA. WINDS COULD POTENTIALLY BECOME LIGHT
AND VRB OR EVEN CALM TUESDAY EVENING. IN THE SHORT TERM...GRADIENT
WILL SLOWLY RELAX OVERNIGHT AND THINK THE PREVAILING GUSTS HAVE
ENDED EXCEPT AT GYY AND ALONG THE LAKE...WITH PREVAILING SPEEDS IN
THE 9-13KT RANGE. CMS
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* LOW CONFIDENCE REGARDING PRECIP TYPE/TIMING/DURATION/INTENSITY
THROUGH THE PERIOD
* MEDIUM CONFIDENCE PREVAILING CIGS WILL BECOME/REMAIN VFR
THROUGH TUESDAY MORNING...LOW CONFIDENCE PREVAILING MVFR CIGS
MAY RETURN TUESDAY MORNING/AFTERNOON
SHEA
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY AND THURSDAY...VFR.
THURSDAY NIGHT...CHANCE OF LIGHT SNOW. MVFR POSSIBLE.
FRIDAY THROUGH SUNDAY...VFR. CMS
&&
.MARINE...
248 AM CST
HIGH PRESSURE EXTENDING FROM THE UPPER MISSISSIPPI VALLEY THROUGH
THE CENTRAL PLAINS WILL SLOWLY SAG ACROSS THE GREAT LAKES REGION
TODAY AND TONIGHT AS A STRONG LOW PRESSURE SYSTEM MOVES ACROSS
NORTHERN MANITOBA INTO THE HUDSON BAY. THIS LOW WILL DRAG A COLD
FRONT ACROSS LAKE MICHIGAN WEDNESDAY. DURING THIS PERIOD...WINDS
OVER THE LAKE WILL GRADUALLY SHIFT FROM NORTHERLY TO SOUTHWESTERLY.
WIND SPEEDS WILL DIMINISH TO AS LOW AS TO TO 15 KT LATE TONIGHT AS
THE SFC RIDGE AXIS CROSSES THE LAKE...BUT AS THE RIDGE PUSHES TO THE
SOUTH AND A SFC TROUGH ASSOCIATED WITH THE COLD FRONT DROPS THROUGH
THE NORTHERN PLAINS LATE TONIGHT...WINDS WILL QUICKLY INCREASE AGAIN
TO AROUND 30 KT. FOLLOWING THE PASSAGE OF THE COLD FRONT...ANOTHER
CANADIAN HIGH PRESSURE SYSTEM WILL DROP SOUTHEAST ACROSS THE PLAINS
THURSDAY AND FRIDAY. THIS SHOULD MAINTAIN A MODERATE PRESSURE
GRADIENT OVER THE GREAT LAKES. THE COMBINATION OF THE MODERATELY
STRONG PRESSURE GRADIENT AND STRONG COLD ADVECTION BEHIND THE
EXITING FRONT WILL KEEP WINDS AROUND 25 TO 30KT OVER THE LAKE FROM
WEDNESDAY THROUGH SATURDAY.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
201 AM CST TUE DEC 6 2011
.DISCUSSION...
852 PM CST
A FEW CHALLENGES REVOLVING AROUND THE LAKE EFFECT PRECIPITATION
THIS EVENING. RADAR IMAGERY SHOWS PRECIPITATION FROM MILWAUKEE
SOUTH INTO NORTHERN WILL COUNTY. WATER VAPOR IMAGERY SHOWS
DEFORMATION ZONE MOVING EAST OF THE FORECAST AREA WITH SUBSIDENCE
AND MID LEVEL DRY AIR MOVING IN FROM THE SOUTHWEST. HAVE SEEN
OVERALL INTENSITY OF RETURNS OFF THE LAKE DECREASE SOMEWHAT AS
THIS FEATURE PROGRESSES THROUGH...BUT FORECAST SOUNDINGS SHOW
LITTLE CHANGE IN THE LOW AND MID LEVELS OVERNIGHT AND SUSPECT AREA
OF PRECIPITATION WILL CONTINUE THROUGH THE REMAINDER OF THE
EVENING AND OVERNIGHT. SOUNDINGS DO SHOW A SLIGHT DECREASE IN THE
INVERSION HEIGHTS BETWEEN 06-09Z...AND MOST OF THE HIGH-RES
GUIDANCE...WITH THE RUC BEING THE EXCEPTION...SHOWS PRECIP
DIMINISHING LATE TONIGHT. SUSPECT THE RUC MAY BE ONTO SOMETHING
THOUGH...WITH NO REAL SENSE OF WHAT MAY CAUSE LAKE EFFECT TO SHUT
OFF OVERNIGHT...THUS WILL BUMP UP POPS FOR TONIGHT.
PRECIP TYPE ALSO A BIG QUESTION MARK. THE 129DM LINE ON THE
1000-850MB THICKNESS LINES UP WELL WITH CURRENT RAIN-SNOW LINE AND
DOES GRADUALLY SHIFT SOUTH THROUGH COOK COUNTY TONIGHT...BUT
LOCALIZED EFFECTS WITH WARM AIR OFF THE LAKE AND URBAN HEAT ISLAND
WILL DELAY THE CHANGE OVER TO SNOW FOR AREAS ALONG THE LAKESHORE AND
PORTIONS OF COOK COUNTY DESPITE THE GRADUAL COOL ADVECTION.
HOWEVER...WET-BULBING EFFECTS UNDER THE HEAVIER SHOWERS MAY
DOMINATE...AND HAS ALREADY BEEN EVIDENT ON DUAL-POL IMAGERY WITH
SOME OF THE SHOWERS THAT PASSED OVER SOUTHERN DUPAGE COUNTY EARLIER
TONIGHT WHERE SNOW BRIEFLY MADE ITS WAY TO THE SURFACE. SO DO EXPECT
A CHANGE OVER TO SNOW AT SOME POINT...BUT HAVE VERY LOW CONFIDENCE
ON PRECISE TIMING. PRECIP AMOUNT REPORTS HAVE BEEN ON THE ORDER OF A
FEW HUNDREDTHS THUS FAR UNDER THE STRONGEST RETURNS...AND SEE NO
REASON FOR THIS TO CHANGE OVERNIGHT NOR HAVE ANY CONCERNS FOR
ACCUMULATIONS. FORECAST UPDATES TO FOLLOW SHORTLY...BMD
//PREV DISCUSSION...
NEAR TERM....THIS AFTERNOON THROUGH TONIGHT...
VISIBLE IMAGERY CONTINUES TO SHOW A THICK STRATUS LAYER OVERHEAD.
VERTICAL GROWTH OF THE CLOUD DESK REMAINS WELL SOUTH OF THE REGION
OVER THE OZARKS AND WESTERN TENNESSEE. WITH THE ABUNDANT SOLAR
SHIELDING...TEMPERATURES THIS AFTERNOON HAVE NOT WARMED MUCH. THUS
EXPECT TEMPS TO REMAIN IN THE MID/UPR 30S. BETTER COLD AIR ADVECTION
HAS CONTINUED TO OCCUR ACROSS WEST CENTRAL ILLINOIS WHERE
TEMPERATURES HAVE HELD AROUND 30...AND IN THE MID 20S ACROSS CENTRAL
MISSOURI. IR IMAGERY THIS AFTERNOON ALSO CONTINUES TO INDICATE MUCH
THICKER CLOUD COVER OVER ILLINOIS/INDIANA.
WSR-88D RADAR WAS DEPICTING PRECIPITATION PUSHING INLAND ACROSS BOTH
COOK AND LAKE COUNTY ILLINOIS...AS LAKE MOISTURE SLOWLY SLIDES
SOUTH/SOUTHWEST. MOISTURE REMAINS VERY SHALLOW AND MINIMAL
LIFT...SUPPORTING PRECIP TO REMAIN AS LIQUID WITH PATCHY DRIZZLE.
FURTHER NORTH A FEW OBSERVATIONS ACROSS WISCONSIN HAVE REPORTED LGT
SN. FOR FAR NORTHEAST ILLINOIS TEMPERATURES ARE WARM ENOUGH TO
MAINTAIN A LIQUID STATE OF PRECIPITATION. QUASI-STATIONARY BOUNDARY
REMAINS TO OUR SOUTHEAST ACROSS THE OZARKS STRETCHING NORTHEAST
THROUGH THE OHIO VALLEY.
OVERNIGHT THE CHALLENGE WILL CONTINUE TO BE COVERAGE OF PRECIP...AND
TEMPERATURES. GUIDANCE HAS SUGGESTED THAT TEMPERATURES WILL COOL
MORE EFFICIENTLY TONIGHT WITH BETTER COLD AIR ADVECTION INTO
NORTHERN IL/NORTHWEST IN...HOWEVER FEEL THIS IS TOO OVERDONE. THUS
HAVE ADJUSTED OVERNIGHT LOWS UP A FEW DEGREES GIVEN THE EXPECTED
THICK CLOUD COVER. WINDS START TO TURN NORTHEASTERLY THIS EVENING
AND CONTINUE OVERNIGHT...WHICH SHOULD AID IN BENDING THE LAKE
MOISTURE SOUTHWEST OR OVER NORTHEAST ILLINOIS. THUS HAVE MAINTAINED
MENTION OF SLIGHT CHANCE WORDING.
VERTICAL LIFT APPEARS TO BUMP UP A TAD OVERNIGHT...WITH SFC TEMPS
PUSHING CLOSER TO FREEZING. MODEL SOUNDINGS INDICATE THAT ANY PRECIP
THAT FALLS THIS EVENING WOULD START AS LIQUID...THEN POSSIBLY START
TO MIX WITH LGT SNOW. AS PREVIOUSLY MENTIONED ABOUT THE MINIMAL
LIFTING MECHANISM...IT IS POSSIBLE THAT PATCHY DRIZZLE COULD OCCUR
BEFORE LGT SNOW WOULD OCCUR.
QPF REMAINS MINIMAL...OR LESS THAN 0.05 THROUGH THE NEXT 24HRS. MORE
THAN LIKELY IT IS CLOSER TO 0.01 TO 0.03. BASED ON THE EXPECTED
TEMPERATURES AND MINIMAL LIFT...ANY SNOW THAT DOES FALL MAY
ACCUMULATE UP TO A QUARTER OF AN INCH. ALTHOUGH THAT BEING
SAID...CONFIDENCE IS LOW THAT THIS SCENARIO WOULD PAN OUT.
TUESDAY THROUGH THURSDAY...
A WEAK WAVE IS PROGGED TO DEVELOP ALONG THE QUASI-STATIONARY
BOUNDARY AND SLIDE NORTHEAST THROUGH MISSOURI. ANTI-CYCLONIC FLOW
REMAINS UPSTREAM ACROSS IOWA/MINNESOTA/WISCONSIN...WHICH SHOULD
START TO TURN OFF LAKE MOISTURE SOMETIME TUE AFTN/EVE. HAVE HELD
ONTO MENTION OF LGT RA/SN THRU THE MORNING HOURS. AFTN TEMPS SHOULD
WARM MARGINALLY TO AROUND THE MID 30S ACROSS MOST OF THE CWFA. BY
TUE AFTN/EVE THE INFLUENCE FROM THE UPSTREAM RIDGE SHOULD FINALLY
ERODE THE THICK STRATUS AND ALLOW PARTLY CLOUD SKIES TO DEVELOP BY
THE LATE AFTN/EVE. THIS COUPLED WITH 850MB THERMAL TROUGH OF -10 TO
-12 DEG...WILL SET THE STAGE FOR OVERNIGHT LOWS IN THE TEENS TO
LOWER 20S.
AS WINDS SLOWLY SHIFT FROM THE NORTHWEST TO THE WEST/SOUTHWEST
WED...THE LAKE MOISTURE WILL BECOME ORIENTED OVER LOWER MICHIGAN.
500MB VORT SLOWLY SLIDES EAST ALONG THE SOUTHERN STREAM...WHILE THE
NORTHERN STREAM REMAINS IN PROGRESSIVE. THE FOCUS WED WILL CONTINUE
TO BE ON THE ARRIVAL OF A POTENT FRONTAL BOUNDARY...THAT IS COUPLED
WITH AN 850MB THERMAL TROUGH OF -20 TO -22 DEG C. THIS WILL PROVIDE
THE COOLEST AIR OF THE SEASON LATER IN THE WEEK TO NORTHERN
IL/NORTHWEST IN.
PRIOR TO THE ARRIVAL OF THIS AIRMASS...MOISTURE IS EXPECTED TO POOL
ALONG THE FRONT AS IT SLOWLY PUSHES SOUTHEAST ACROSS THE PLAINS
THURSDAY. GUIDANCE HAS FLUCTUATED ON HOW THIS FEATURE WILL
UNFOLD...AND IT REMAINS POSSIBLE THAT A WEAK WAVE WILL DEVELOP ALONG
THE LEE-SIDE OF THE 500MB TROUGH AXIS. THIS SCENARIO COULD RESULT IN
LGT SNOW OVERSPREADING NORTHERN IL/NORTHWEST IN THUR AFTN AS THE
POTENT THERMAL TROUGH ARRIVES ALOFT. TEMPS THUR WILL REMAIN IN THE
LOW/MID 30S.
BEACHLER
LONG TERM...THURSDAY NIGHT THROUGH MONDAY
MAIN CONCERNS IN THE EXTENDED PORTION OF THE FORECAST ARE LIGHT SNOW
POTENTIAL THURSDAY NIGHT INTO EARLY FRIDAY...FOLLOWED BY THE FIRST
BLAST OF ARCTIC AIR OF THE SEASON FOR FRIDAY INTO EARLY SATURDAY.
ON THURSDAY NIGHT...AS MENTIONED ABOVE...DIGGING H5 TROUGH WILL
SPAWN A WEAK SURFACE LOW WHICH WILL TRACK ACROSS NORTHERN GREAT
LAKES AND SEND AN ARCTIC FRONTAL BOUNDARY TOWARD AREA. MODELS HAVE
BEEN CONSISTENT IN SPITTING OUT A STRIPE OF VERY LIGHT QPF NEAR OR
OVER CWA IN RESPONSE TO THIS FEATURE. WITH NEGATIVE TEEN AIR AT
H85 BUILDING IN FROM THE NORTH BEHIND ARCTIC FRONT...SUSPECT WAVE
WILL RIDE ALONG LOW LEVEL BAROCLINIC ZONE. A PEEK AT GFS TIME
HEIGHT AT ORD FOR THURSDAY NIGHT PERIOD SHOWS SATURATION AND
ADEQUATE LIFT INTO -15C FAVORED SNOW GROWTH ZONE.
THEREFORE...DESPITE QPF ONLY IN THE HUNDREDTHS UP TO MAYBE A TENTH
OR SLIGHTLY MORE...WITH VERY COLD AIR MASS...SNOW WOULD BE HIGH
RATIO AND POSSIBLY RESULT IN FIRST WIDESPREAD LIGHT ACCUMULATING
SNOW OF THE SEASON FOR MANY (IF SCENARIO PANS OUT...POTENTIAL FOR
AN INCH OR TWO OF SNOW). FOR NOW...HAVE BUMPED UP POPS IN GRIDS TO
CHANCE ACROSS THE AREA GIVEN SOME UNCERTAINTY IN EXACTLY WHERE
BEST SNOW POTENTIAL WILL OCCUR. LIGHT SNOW MAY LINGER INTO EARLY
FRIDAY FOR EASTERN PORTION OF CWA BEFORE WAVE SHIFTS OFF TO THE
EAST.
THEREAFTER...ON FRIDAY...STRONG CAA WILL BE IN FULL FORCE WITH SHARP
THERMAL TROUGH ARRIVING OVERHEAD LATE IN THE DAY. OPERATIONAL MODELS
AND ENSEMBLES HAVE BACKED OFF EVER SO SLIGHTLY ON JUST HOW COLD
ARCTIC AIR MASS WILL BE...BUT -15C OR SO AT H85 AND -8 TO -10 AT H95
WILL BE PLENTY COLD. TEMPERATURES WILL STRUGGLE INTO THE MID TO
UPPER 20S FRIDAY AFTERNOON WITH A PERSISTENT WNW BREEZE LEADING TO
LOW WIND CHILL VALUES. AXIS OF ARCTIC HIGH WILL PASS CLOSEST ON
FRIDAY NIGHT...LEADING TO STRONG RADIATIONAL COOLING. IF MINOR SNOW
COVER IS PRESENT...LOW TO MID TEENS...UPPER TEENS IN DOWNTOWN
CHICAGO...IN GRIDS FOR LOW EARLY SATURDAY MORNING MIGHT BE A FEW
DEGREES TOO HIGH. SW FLOW...STEADY WARMING ALOFT AND LIKELY FULL
SUNSHINE ON SATURDAY WILL ALLOW FOR SOME RECOVERY FROM VERY COLD
START TO DAY...BUT SUSPECT IT WILL BE TOUGH TO MAKE UP A LOT OF
GROUND DUE TO LIMITED DAYLIGHT THIS TIME OF YEAR. THUS SHAVED OFF A
DEGREE FROM MODEL BLEND FOR MAX TEMPERATURES ON SATURDAY...YIELDING
HIGHS IN THE UPPER 20S TO AROUND 30 DEGREES. SUNDAY AND MONDAY LOOK
TO BE MAINLY DRY WITH TEMPERATURES RETURNING TO CLOSE TO SEASONAL
NORMS DUE TO SOUTHERLY FLOW AND CONTINUED WARMING OF THE COLUMN. A
FRONTAL BOUNDARY MAY DROP SOUTH THROUGH THE AREA LATE MONDAY...
BRINGING NEXT CHANCE FOR LIGHT PRECIP...BUT LARGE MODEL UNCERTAINTY
THIS FAR OUT PRECLUDES ANYTHING MORE THAN SLIGHT POPS FOR MONDAY
NIGHT.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* POTENTIAL FOR LAKE EFFECT RAIN/SNOW SHOWERS THROUGH THE
AFTERNOON
* PERIODS OF MVFR CIGS THROUGH TUESDAY EVENING.
SHEA
//DISCUSSION...UPDATED 06Z...
MAIN FORECAST CONCERN AND CHALLENGE REMAINS THE LAKE EFFECT RAIN/
SNOW SHOWERS. OVERALL INTENSITY HAS DIMINISHED SOME FROM EARLIER
THIS EVENING BUT STILL MANY SHOWERS FROM FAR SOUTHEAST WI INTO
NORTHEAST IL. COOLER AIR SLOWLY FILTERING IN FROM THE NORTH HAS
CHANGED PRECIP TO MAINLY SNOW ACROSS SOUTHEAST WI INTO FAR
NORTHEAST IL...AS WELL AS LOCATIONS FARTHER INLAND...SUCH AS DPA
WHERE TEMPS HAVE ALSO COOLED A FEW DEGREES. FORECAST SOUNDINGS
CONTINUE TO SHOW THE INVERSION HEIGHT LOWERING SOME THROUGH THE
OVERNIGHT HRS AND THIS SHOULD LIMIT THE COVERAGE AND INTENSITY OF
THE LAKE EFFECT SHOWERS OVERNIGHT. WHILE THERE WILL STILL LIKELY
BE PERIODS OF LIGHT RAIN AND/OR LIGHT SNOW...CONFIDENCE IN TRYING
TO TIME ANY OF THIS PRECIP IS VERY LOW. AND FOR THAT REASON...HAVE
GONE WITH A VICINITY MENTION...THOUGH LATER UPDATES FOR PREVAILING
OR TEMPO PRECIP MAY BE NEEDED. LITTLE CHANGE TO THE AIRMASS OR LOW
LEVEL PROFILES INTO TUESDAY AFTERNOON AND THERE COULD BE
ADDITIONAL LAKE EFFECT SHOWERS THROUGH SUNSET...PERHAPS AIDED BY
DIURNAL WARMING BY MID/LATE MORNING. CONFIDENCE VERY LOW HERE AS
WELL.
OUTSIDE OF PRECIP AREAS...CIGS HAVE GENERALLY LIFTED INTO LOW VFR
WITH A FEW PATCHES OF HIGH MVFR CIGS. EXPECT THIS OVERALL TREND TO
CONTINUE WITH MVFR POSSIBLE IN AREAS OF HEAVIER PRECIP. THOUGH AM
CONCERNED THAT THERE COULD BE ANOTHER PERIOD OF MVFR CIGS TUESDAY
AFTERNOON. WITH A RIDGE OF HIGH PRESSURE MOVING ACROSS THE AREA
TUESDAY NIGHT...ANY MVFR CIGS MAY GET TRAPPED BELOW THE INVERSION
AND COULD PERSIST WELL INTO TUESDAY NIGHT.
NORTHEAST WINDS WILL SLOWLY TURN MORE NORTHERLY TUESDAY AFTERNOON
THEN SHOULD FLOP WESTERLY TUESDAY EVENING AS THE ABOVE MENTIONED
RIDGE BUILDS ACROSS THE AREA. WINDS COULD POTENTIALLY BECOME LIGHT
AND VRB OR EVEN CALM TUESDAY EVENING. IN THE SHORT TERM...GRADIENT
WILL SLOWLY RELAX OVERNIGHT AND THINK THE PREVAILING GUSTS HAVE
ENDED EXCEPT AT GYY AND ALONG THE LAKE...WITH PREVAILING SPEEDS IN
THE 9-13KT RANGE. CMS
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* LOW CONFIDENCE REGARDING PRECIP TYPE/TIMING/DURATION/INTENSITY
THROUGH THE PERIOD
* MEDIUM CONFIDENCE PREVAILING CIGS WILL BECOME/REMAIN VFR
THROUGH TUESDAY MORNING...LOW CONFIDENCE PREVAILING MVFR CIGS
MAY RETURN TUESDAY MORNING/AFTERNOON
SHEA
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY AND THURSDAY...VFR.
THURSDAY NIGHT...CHANCE OF LIGHT SNOW. MVFR POSSIBLE.
FRIDAY THROUGH SUNDAY...VFR. CMS
&&
.MARINE...
147 PM CST
HIGH PRESSURE ACROSS THE PLAINS WILL SLOWLY SAG SOUTHWARD TUESDAY
AND TUESDAY NIGHT AS A STRONG AREA OF LOW PRESSURE MOVES ACROSS
NORTHERN MANITOBA INTO THE HUDSON BAY. AS A CONSEQUENCE OF
THIS...WINDS ARE EXPECTED TO BECOME WEST SOUTHWESTERLY AND INCREASE
TO NEAR 30 KT LATE TUESDAY NIGHT AND ON WEDNESDAY. THEN WEDNESDAY
NIGHT A STRONG COLD FRONT...ASSOCIATED WITH THE LOW ACROSS NORTHERN
CANADA...WILL PUSH SOUTH ACROSS LAKE MICHIGAN. WEST TO NORTHWEST
WINDS WILL OCCUR IN THE WAKE OF THIS FRONT. FOLLOWING THIS
FRONT...ANOTHER CANADIAN HIGH PRESSURE SYSTEM WILL DROP SOUTHEAST
ACROSS THE PLAINS THURSDAY AND FRIDAY. THIS SHOULD HELP SUPPORT A
DECENT PRESSURE GRADIENT ACROSS THE GREAT LAKES. THUS...IN
COMBINATION WITH A VERY COLD AIR MASS OVER THE RELATIVELY WARM
WATERS OF LAKE MICHIGAN...WINDS WILL LIKELY REMAIN ELEVATED IN THE
20 TO 25 KT RANGE DURING THIS PERIOD.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1101 PM CST MON DEC 5 2011
.DISCUSSION...
852 PM CST
A FEW CHALLENGES REVOLVING AROUND THE LAKE EFFECT PRECIPITATION
THIS EVENING. RADAR IMAGERY SHOWS PRECIPITATION FROM MILWAUKEE
SOUTH INTO NORTHERN WILL COUNTY. WATER VAPOR IMAGERY SHOWS
DEFORMATION ZONE MOVING EAST OF THE FORECAST AREA WITH SUBSIDENCE
AND MID LEVEL DRY AIR MOVING IN FROM THE SOUTHWEST. HAVE SEEN
OVERALL INTENSITY OF RETURNS OFF THE LAKE DECREASE SOMEWHAT AS
THIS FEATURE PROGRESSES THROUGH...BUT FORECAST SOUNDINGS SHOW
LITTLE CHANGE IN THE LOW AND MID LEVELS OVERNIGHT AND SUSPECT AREA
OF PRECIPITATION WILL CONTINUE THROUGH THE REMAINDER OF THE
EVENING AND OVERNIGHT. SOUNDINGS DO SHOW A SLIGHT DECREASE IN THE
INVERSION HEIGHTS BETWEEN 06-09Z...AND MOST OF THE HIGH-RES
GUIDANCE...WITH THE RUC BEING THE EXCEPTION...SHOWS PRECIP
DIMINISHING LATE TONIGHT. SUSPECT THE RUC MAY BE ONTO SOMETHING
THOUGH...WITH NO REAL SENSE OF WHAT MAY CAUSE LAKE EFFECT TO SHUT
OFF OVERNIGHT...THUS WILL BUMP UP POPS FOR TONIGHT.
PRECIP TYPE ALSO A BIG QUESTION MARK. THE 129DM LINE ON THE
1000-850MB THICKNESS LINES UP WELL WITH CURRENT RAIN-SNOW LINE AND
DOES GRADUALLY SHIFT SOUTH THROUGH COOK COUNTY TONIGHT...BUT
LOCALIZED EFFECTS WITH WARM AIR OFF THE LAKE AND URBAN HEAT ISLAND
WILL DELAY THE CHANGE OVER TO SNOW FOR AREAS ALONG THE LAKESHORE AND
PORTIONS OF COOK COUNTY DESPITE THE GRADUAL COOL ADVECTION.
HOWEVER...WET-BULBING EFFECTS UNDER THE HEAVIER SHOWERS MAY
DOMINATE...AND HAS ALREADY BEEN EVIDENT ON DUAL-POL IMAGERY WITH
SOME OF THE SHOWERS THAT PASSED OVER SOUTHERN DUPAGE COUNTY EARLIER
TONIGHT WHERE SNOW BRIEFLY MADE ITS WAY TO THE SURFACE. SO DO EXPECT
A CHANGE OVER TO SNOW AT SOME POINT...BUT HAVE VERY LOW CONFIDENCE
ON PRECISE TIMING. PRECIP AMOUNT REPORTS HAVE BEEN ON THE ORDER OF A
FEW HUNDREDTHS THUS FAR UNDER THE STRONGEST RETURNS...AND SEE NO
REASON FOR THIS TO CHANGE OVERNIGHT NOR HAVE ANY CONCERNS FOR
ACCUMULATIONS. FORECAST UPDATES TO FOLLOW SHORTLY...BMD
//PREV DISCUSSION...
NEAR TERM....THIS AFTERNOON THROUGH TONIGHT...
VISIBLE IMAGERY CONTINUES TO SHOW A THICK STRATUS LAYER OVERHEAD.
VERTICAL GROWTH OF THE CLOUD DESK REMAINS WELL SOUTH OF THE REGION
OVER THE OZARKS AND WESTERN TENNESSEE. WITH THE ABUNDANT SOLAR
SHIELDING...TEMPERATURES THIS AFTERNOON HAVE NOT WARMED MUCH. THUS
EXPECT TEMPS TO REMAIN IN THE MID/UPR 30S. BETTER COLD AIR ADVECTION
HAS CONTINUED TO OCCUR ACROSS WEST CENTRAL ILLINOIS WHERE
TEMPERATURES HAVE HELD AROUND 30...AND IN THE MID 20S ACROSS CENTRAL
MISSOURI. IR IMAGERY THIS AFTERNOON ALSO CONTINUES TO INDICATE MUCH
THICKER CLOUD COVER OVER ILLINOIS/INDIANA.
WSR-88D RADAR WAS DEPICTING PRECIPITATION PUSHING INLAND ACROSS BOTH
COOK AND LAKE COUNTY ILLINOIS...AS LAKE MOISTURE SLOWLY SLIDES
SOUTH/SOUTHWEST. MOISTURE REMAINS VERY SHALLOW AND MINIMAL
LIFT...SUPPORTING PRECIP TO REMAIN AS LIQUID WITH PATCHY DRIZZLE.
FURTHER NORTH A FEW OBSERVATIONS ACROSS WISCONSIN HAVE REPORTED LGT
SN. FOR FAR NORTHEAST ILLINOIS TEMPERATURES ARE WARM ENOUGH TO
MAINTAIN A LIQUID STATE OF PRECIPITATION. QUASI-STATIONARY BOUNDARY
REMAINS TO OUR SOUTHEAST ACROSS THE OZARKS STRETCHING NORTHEAST
THROUGH THE OHIO VALLEY.
OVERNIGHT THE CHALLENGE WILL CONTINUE TO BE COVERAGE OF PRECIP...AND
TEMPERATURES. GUIDANCE HAS SUGGESTED THAT TEMPERATURES WILL COOL
MORE EFFICIENTLY TONIGHT WITH BETTER COLD AIR ADVECTION INTO
NORTHERN IL/NORTHWEST IN...HOWEVER FEEL THIS IS TOO OVERDONE. THUS
HAVE ADJUSTED OVERNIGHT LOWS UP A FEW DEGREES GIVEN THE EXPECTED
THICK CLOUD COVER. WINDS START TO TURN NORTHEASTERLY THIS EVENING
AND CONTINUE OVERNIGHT...WHICH SHOULD AID IN BENDING THE LAKE
MOISTURE SOUTHWEST OR OVER NORTHEAST ILLINOIS. THUS HAVE MAINTAINED
MENTION OF SLIGHT CHANCE WORDING.
VERTICAL LIFT APPEARS TO BUMP UP A TAD OVERNIGHT...WITH SFC TEMPS
PUSHING CLOSER TO FREEZING. MODEL SOUNDINGS INDICATE THAT ANY PRECIP
THAT FALLS THIS EVENING WOULD START AS LIQUID...THEN POSSIBLY START
TO MIX WITH LGT SNOW. AS PREVIOUSLY MENTIONED ABOUT THE MINIMAL
LIFTING MECHANISM...IT IS POSSIBLE THAT PATCHY DRIZZLE COULD OCCUR
BEFORE LGT SNOW WOULD OCCUR.
QPF REMAINS MINIMAL...OR LESS THAN 0.05 THROUGH THE NEXT 24HRS. MORE
THAN LIKELY IT IS CLOSER TO 0.01 TO 0.03. BASED ON THE EXPECTED
TEMPERATURES AND MINIMAL LIFT...ANY SNOW THAT DOES FALL MAY
ACCUMULATE UP TO A QUARTER OF AN INCH. ALTHOUGH THAT BEING
SAID...CONFIDENCE IS LOW THAT THIS SCENARIO WOULD PAN OUT.
TUESDAY THROUGH THURSDAY...
A WEAK WAVE IS PROGGED TO DEVELOP ALONG THE QUASI-STATIONARY
BOUNDARY AND SLIDE NORTHEAST THROUGH MISSOURI. ANTI-CYCLONIC FLOW
REMAINS UPSTREAM ACROSS IOWA/MINNESOTA/WISCONSIN...WHICH SHOULD
START TO TURN OFF LAKE MOISTURE SOMETIME TUE AFTN/EVE. HAVE HELD
ONTO MENTION OF LGT RA/SN THRU THE MORNING HOURS. AFTN TEMPS SHOULD
WARM MARGINALLY TO AROUND THE MID 30S ACROSS MOST OF THE CWFA. BY
TUE AFTN/EVE THE INFLUENCE FROM THE UPSTREAM RIDGE SHOULD FINALLY
ERODE THE THICK STRATUS AND ALLOW PARTLY CLOUD SKIES TO DEVELOP BY
THE LATE AFTN/EVE. THIS COUPLED WITH 850MB THERMAL TROUGH OF -10 TO
-12 DEG...WILL SET THE STAGE FOR OVERNIGHT LOWS IN THE TEENS TO
LOWER 20S.
AS WINDS SLOWLY SHIFT FROM THE NORTHWEST TO THE WEST/SOUTHWEST
WED...THE LAKE MOISTURE WILL BECOME ORIENTED OVER LOWER MICHIGAN.
500MB VORT SLOWLY SLIDES EAST ALONG THE SOUTHERN STREAM...WHILE THE
NORTHERN STREAM REMAINS IN PROGRESSIVE. THE FOCUS WED WILL CONTINUE
TO BE ON THE ARRIVAL OF A POTENT FRONTAL BOUNDARY...THAT IS COUPLED
WITH AN 850MB THERMAL TROUGH OF -20 TO -22 DEG C. THIS WILL PROVIDE
THE COOLEST AIR OF THE SEASON LATER IN THE WEEK TO NORTHERN
IL/NORTHWEST IN.
PRIOR TO THE ARRIVAL OF THIS AIRMASS...MOISTURE IS EXPECTED TO POOL
ALONG THE FRONT AS IT SLOWLY PUSHES SOUTHEAST ACROSS THE PLAINS
THURSDAY. GUIDANCE HAS FLUCTUATED ON HOW THIS FEATURE WILL
UNFOLD...AND IT REMAINS POSSIBLE THAT A WEAK WAVE WILL DEVELOP ALONG
THE LEE-SIDE OF THE 500MB TROUGH AXIS. THIS SCENARIO COULD RESULT IN
LGT SNOW OVERSPREADING NORTHERN IL/NORTHWEST IN THUR AFTN AS THE
POTENT THERMAL TROUGH ARRIVES ALOFT. TEMPS THUR WILL REMAIN IN THE
LOW/MID 30S.
BEACHLER
LONG TERM...THURSDAY NIGHT THROUGH MONDAY
MAIN CONCERNS IN THE EXTENDED PORTION OF THE FORECAST ARE LIGHT SNOW
POTENTIAL THURSDAY NIGHT INTO EARLY FRIDAY...FOLLOWED BY THE FIRST
BLAST OF ARCTIC AIR OF THE SEASON FOR FRIDAY INTO EARLY SATURDAY.
ON THURSDAY NIGHT...AS MENTIONED ABOVE...DIGGING H5 TROUGH WILL
SPAWN A WEAK SURFACE LOW WHICH WILL TRACK ACROSS NORTHERN GREAT
LAKES AND SEND AN ARCTIC FRONTAL BOUNDARY TOWARD AREA. MODELS HAVE
BEEN CONSISTENT IN SPITTING OUT A STRIPE OF VERY LIGHT QPF NEAR OR
OVER CWA IN RESPONSE TO THIS FEATURE. WITH NEGATIVE TEEN AIR AT
H85 BUILDING IN FROM THE NORTH BEHIND ARCTIC FRONT...SUSPECT WAVE
WILL RIDE ALONG LOW LEVEL BAROCLINIC ZONE. A PEEK AT GFS TIME
HEIGHT AT ORD FOR THURSDAY NIGHT PERIOD SHOWS SATURATION AND
ADEQUATE LIFT INTO -15C FAVORED SNOW GROWTH ZONE.
THEREFORE...DESPITE QPF ONLY IN THE HUNDREDTHS UP TO MAYBE A TENTH
OR SLIGHTLY MORE...WITH VERY COLD AIR MASS...SNOW WOULD BE HIGH
RATIO AND POSSIBLY RESULT IN FIRST WIDESPREAD LIGHT ACCUMULATING
SNOW OF THE SEASON FOR MANY (IF SCENARIO PANS OUT...POTENTIAL FOR
AN INCH OR TWO OF SNOW). FOR NOW...HAVE BUMPED UP POPS IN GRIDS TO
CHANCE ACROSS THE AREA GIVEN SOME UNCERTAINTY IN EXACTLY WHERE
BEST SNOW POTENTIAL WILL OCCUR. LIGHT SNOW MAY LINGER INTO EARLY
FRIDAY FOR EASTERN PORTION OF CWA BEFORE WAVE SHIFTS OFF TO THE
EAST.
THEREAFTER...ON FRIDAY...STRONG CAA WILL BE IN FULL FORCE WITH SHARP
THERMAL TROUGH ARRIVING OVERHEAD LATE IN THE DAY. OPERATIONAL MODELS
AND ENSEMBLES HAVE BACKED OFF EVER SO SLIGHTLY ON JUST HOW COLD
ARCTIC AIR MASS WILL BE...BUT -15C OR SO AT H85 AND -8 TO -10 AT H95
WILL BE PLENTY COLD. TEMPERATURES WILL STRUGGLE INTO THE MID TO
UPPER 20S FRIDAY AFTERNOON WITH A PERSISTENT WNW BREEZE LEADING TO
LOW WIND CHILL VALUES. AXIS OF ARCTIC HIGH WILL PASS CLOSEST ON
FRIDAY NIGHT...LEADING TO STRONG RADIATIONAL COOLING. IF MINOR SNOW
COVER IS PRESENT...LOW TO MID TEENS...UPPER TEENS IN DOWNTOWN
CHICAGO...IN GRIDS FOR LOW EARLY SATURDAY MORNING MIGHT BE A FEW
DEGREES TOO HIGH. SW FLOW...STEADY WARMING ALOFT AND LIKELY FULL
SUNSHINE ON SATURDAY WILL ALLOW FOR SOME RECOVERY FROM VERY COLD
START TO DAY...BUT SUSPECT IT WILL BE TOUGH TO MAKE UP A LOT OF
GROUND DUE TO LIMITED DAYLIGHT THIS TIME OF YEAR. THUS SHAVED OFF A
DEGREE FROM MODEL BLEND FOR MAX TEMPERATURES ON SATURDAY...YIELDING
HIGHS IN THE UPPER 20S TO AROUND 30 DEGREES. SUNDAY AND MONDAY LOOK
TO BE MAINLY DRY WITH TEMPERATURES RETURNING TO CLOSE TO SEASONAL
NORMS DUE TO SOUTHERLY FLOW AND CONTINUED WARMING OF THE COLUMN. A
FRONTAL BOUNDARY MAY DROP SOUTH THROUGH THE AREA LATE MONDAY...
BRINGING NEXT CHANCE FOR LIGHT PRECIP...BUT LARGE MODEL UNCERTAINTY
THIS FAR OUT PRECLUDES ANYTHING MORE THAN SLIGHT POPS FOR MONDAY
NIGHT.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* POTENTIAL FOR LAKE EFFECT RAIN/SNOW SHOWERS THROUGH TUESDAY
AFTERNOON.
* PERIODS OF MVFR CIGS THROUGH TUESDAY EVENING. CMS
//DISCUSSION...UPDATED 06Z...
MAIN FORECAST CONCERN AND CHALLENGE REMAINS THE LAKE EFFECT RAIN/
SNOW SHOWERS. OVERALL INTENSITY HAS DIMINISHED SOME FROM EARLIER
THIS EVENING BUT STILL MANY SHOWERS FROM FAR SOUTHEAST WI INTO
NORTHEAST IL. COOLER AIR SLOWLY FILTERING IN FROM THE NORTH HAS
CHANGED PRECIP TO MAINLY SNOW ACROSS SOUTHEAST WI INTO FAR
NORTHEAST IL...AS WELL AS LOCATIONS FARTHER INLAND...SUCH AS DPA
WHERE TEMPS HAVE ALSO COOLED A FEW DEGREES. FORECAST SOUNDINGS
CONTINUE TO SHOW THE INVERSION HEIGHT LOWERING SOME THROUGH THE
OVERNIGHT HRS AND THIS SHOULD LIMIT THE COVERAGE AND INTENSITY OF
THE LAKE EFFECT SHOWERS OVERNIGHT. WHILE THERE WILL STILL LIKELY
BE PERIODS OF LIGHT RAIN AND/OR LIGHT SNOW...CONFIDENCE IN TRYING
TO TIME ANY OF THIS PRECIP IS VERY LOW. AND FOR THAT REASON...HAVE
GONE WITH A VICINITY MENTION...THOUGH LATER UPDATES FOR PREVAILING
OR TEMPO PRECIP MAY BE NEEDED. LITTLE CHANGE TO THE AIRMASS OR LOW
LEVEL PROFILES INTO TUESDAY AFTERNOON AND THERE COULD BE
ADDITIONAL LAKE EFFECT SHOWERS THROUGH SUNSET...PERHAPS AIDED BY
DIURNAL WARMING BY MID/LATE MORNING. CONFIDENCE VERY LOW HERE AS
WELL.
OUTSIDE OF PRECIP AREAS...CIGS HAVE GENERALLY LIFTED INTO LOW VFR
WITH A FEW PATCHES OF HIGH MVFR CIGS. EXPECT THIS OVERALL TREND TO
CONTINUE WITH MVFR POSSIBLE IN AREAS OF HEAVIER PRECIP. THOUGH AM
CONCERNED THAT THERE COULD BE ANOTHER PERIOD OF MVFR CIGS TUESDAY
AFTERNOON. WITH A RIDGE OF HIGH PRESSURE MOVING ACROSS THE AREA
TUESDAY NIGHT...ANY MVFR CIGS MAY GET TRAPPED BELOW THE INVERSION
AND COULD PERSIST WELL INTO TUESDAY NIGHT.
NORTHEAST WINDS WILL SLOWLY TURN MORE NORTHERLY TUESDAY AFTERNOON
THEN SHOULD FLOP WESTERLY TUESDAY EVENING AS THE ABOVE MENTIONED
RIDGE BUILDS ACROSS THE AREA. WINDS COULD POTENTIALLY BECOME LIGHT
AND VRB OR EVEN CALM TUESDAY EVENING. IN THE SHORT TERM...GRADIENT
WILL SLOWLY RELAX OVERNIGHT AND THINK THE PREVAILING GUSTS HAVE
ENDED EXCEPT AT GYY AND ALONG THE LAKE...WITH PREVAILING SPEEDS IN
THE 9-13KT RANGE. CMS
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* LOW CONFIDENCE REGARDING PRECIP TYPE/TIMING/DURATION/INTENSITY
THROUGH THE PERIOD.
* MEDIUM CONFIDENCE PREVAILING CIGS WILL BECOME/REMAIN VFR THROUGH
TUESDAY MORNING...LOW CONFIDENCE PREVAILING MVFR CIGS MAY RETURN
TUESDAY MORNING/AFTERNOON. CMS
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY AND THURSDAY...VFR.
THURSDAY NIGHT...CHANCE OF LIGHT SNOW. MVFR POSSIBLE.
FRIDAY THROUGH SUNDAY...VFR. CMS
&&
.MARINE...
147 PM CST
HIGH PRESSURE ACROSS THE PLAINS WILL SLOWLY SAG SOUTHWARD TUESDAY
AND TUESDAY NIGHT AS A STRONG AREA OF LOW PRESSURE MOVES ACROSS
NORTHERN MANITOBA INTO THE HUDSON BAY. AS A CONSEQUENCE OF
THIS...WINDS ARE EXPECTED TO BECOME WEST SOUTHWESTERLY AND INCREASE
TO NEAR 30 KT LATE TUESDAY NIGHT AND ON WEDNESDAY. THEN WEDNESDAY
NIGHT A STRONG COLD FRONT...ASSOCIATED WITH THE LOW ACROSS NORTHERN
CANADA...WILL PUSH SOUTH ACROSS LAKE MICHIGAN. WEST TO NORTHWEST
WINDS WILL OCCUR IN THE WAKE OF THIS FRONT. FOLLOWING THIS
FRONT...ANOTHER CANADIAN HIGH PRESSURE SYSTEM WILL DROP SOUTHEAST
ACROSS THE PLAINS THURSDAY AND FRIDAY. THIS SHOULD HELP SUPPORT A
DECENT PRESSURE GRADIENT ACROSS THE GREAT LAKES. THUS...IN
COMBINATION WITH A VERY COLD AIR MASS OVER THE RELATIVELY WARM
WATERS OF LAKE MICHIGAN...WINDS WILL LIKELY REMAIN ELEVATED IN THE
20 TO 25 KT RANGE DURING THIS PERIOD.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 9 PM TUESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1139 AM CST TUE DEC 6 2011
...UPDATE TO AVIATION...
&&
.AVIATION...
VFR CONDITIONS EXPECTED THROUGH THE PERIOD. NORTH WINDS BECOME
VARIABLE OVERNIGHT AND SHIFT AROUND TO THE SOUTHWEST ON WEDNESDAY.
SPEEDS REMAIN BELOW 12 KTS.
67
&&
.PREV DISCUSSION...
/ISSUED 536 AM CST TUE DEC 6 2011/
SHORT RANGE FORECAST (TODAY AND WEDNESDAY)...
8Z WATER VAPOR IMAGERY AND ASSOCIATED 500 MB RUC ANALYSIS SHOWS A
HIGHLY AMPLIFIED POSITIVELY TILTED TROUGH OVER THE CENTRAL PLAINS
WITH ITS AXIS EXTENDING FROM LAKE SUPERIOR AND RUNNING SOUTHWESTWARD
THROUGH NEBRASKA AND INTO THE FOUR CORNER REGION. CURRENTLY
TEMPERATURES ACROSS CENTRAL NEBRASKA ARE BELOW ZERO AS THE SURFACE
RIDGE OF HIGH PRESSURE IS CENTERED OVER NEBRASKA. THE COLDEST
LOCATION REMAINS KBBW WHERE THE TEMP AT 9Z WAS -11. ACROSS NORTHEAST
KANSAS TEMPERATURES REMAIN IN THE MID TEENS WITH WIND CHILLS IN THE
SINGLE DIGITS. ACROSS SOUTHEAST KANSAS MEAGER FRONTOGENETICAL AND
ISENTROPIC LIFT HAS BROUGHT SOME LIGHT SNOW...MAINLY IN THE FORM OF
NON-ACCUMULATING FLURRIES. BY MID-DAY ON TUESDAY EXPECT THE
LOW/MID LEVEL LIFT AND SATURATED CONDITIONS TO MOVE OFF THE EAST OF
THE FORECAST AREA ALLOWING A GRADUAL BREAKDOWN OF THE STRATUS DECK.
EXPECT VERY LIGHT COLD AIR ADVECTION TO PERSIST THROUGHOUT THE DAY
AS WINDS STAY FROM THE NORTH WHERE THE SURFACE HIGH WILL RESIDE. AS
A RESULT OF THE COLD AIR ADVECTION AND THE ABBREVIATED DURATION
OF CLEAR SKIES EXPECT TEMPS ON TUESDAY TO REMAIN IN THE MID TO
UPPER 20S ACROSS AREAS NORTH OF THE KANSAS TURNPIKE...WITH TEMPS
SOUTH AND EAST OF THE TURNPIKE REACHING THE LOWER 30S. FOR TUESDAY
NIGHT THE SURFACE HIGH MOVES EASTWARD AND CENTERS OVER NORTHEAST
KANSAS. EXPECT SKIES TO CLEAR OUT AND WINDS TO GO CALM OVERNIGHT.
EXPECT TUESDAY NIGHT/WED MORNING TO BE THE COLDEST PERIOD FOR THIS
FORECAST PACKAGE AS TEMPS WILL DROP TO THE LOWER TEENS ACROSS THE
ENTIRE AREA...WITH THE LOWER TERRAIN OF RIVER VALLEYS PERHAPS
DROPPING INTO THE SINGLE DIGITS. BY WEDNESDAY THE ARCTIC AIRMASS
WHICH BROUGHT THE FRIGID TEMPS FOR THE EARLY PART OF THE WEEK WILL
SHIFT EAST AND WARMER AIR WILL ADVECT INTO THE AREA...ALLOWING
WEDNESDAY`S TEMPS TO REACH THE UPPER 30S TO LOWER 40S.
MID-RANGE AND EXTENDED FORECAST (THURSDAY THROUGH MONDAY)...
FAIRLY INACTIVE WEATHER PATTERN SHAPING UP FOR THE MIDDLE TO LATE
PART OF THE WEEK AND INTO THE WEEKEND...AS NO REAL MID OR UPPER
LEVEL FORCING ENTERS THE AREA. ALTHOUGH THE DAY TIME HOURS WILL BE
SLIGHTLY WARMER FOR THE MIDDLE TO LATE PART OF THE WEEK OVERNIGHT
LOWS WILL STILL DROP TO THE MID TEENS TO UPPER 20S AS ANOTHER MASS
OF COLD AIR DIPS INTO THE AREA. PERHAPS THE ONLY WEATHER TO AFFECT
NORTHEAST KANSAS WILL BE LATE IN THE WEEK AS AN UPPER LEVEL LOW DIGS
SOUTHWARD THROUGH NEBRASKA BUT ITS SOUTHWARD PROGRESS STOPS IN
SOUTHERN NEBRASKA BEFORE IT EJECTS EASTWARD. WITH LITTLE MOISTURE
FOR THE SYSTEM TO WORK WITH EXPECT ONLY A FEW FLURRIES ACROSS AREAS
NORTH OF HIGHWAY 24 THURSDAY NIGHT/FRIDAY MORNING. THEREAFTER EXPECT
A DRY FORECAST FOR THE REST OF THE WEEK AND THROUGH THE WEEKEND WITH
DAYTIME HIGHS IN THE 40S AND OVERNIGHT LOWS IN THE UPPER 20S TO
LOWER 30S.
JL
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
536 AM CST TUE DEC 6 2011
...UPDATE TO AVIATION...
.DISCUSSION...
SHORT RANGE FORECAST (TODAY AND WEDNESDAY)...
8Z WATER VAPOR IMAGERY AND ASSOCIATED 500 MB RUC ANALYSIS SHOWS A
HIGHLY AMPLIFIED POSITIVELY TILTED TROUGH OVER THE CENTRAL PLAINS
WITH ITS AXIS EXTENDING FROM LAKE SUPERIOR AND RUNNING SOUTHWESTWARD
THROUGH NEBRASKA AND INTO THE FOUR CORNER REGION. CURRENTLY
TEMPERATURES ACROSS CENTRAL NEBRASKA ARE BELOW ZERO AS THE SURFACE
RIDGE OF HIGH PRESSURE IS CENTERED OVER NEBRASKA. THE COLDEST
LOCATION REMAINS KBBW WHERE THE TEMP AT 9Z WAS -11. ACROSS NORTHEAST
KANSAS TEMPERATURES REMAIN IN THE MID TEENS WITH WIND CHILLS IN THE
SINGLE DIGITS. ACROSS SOUTHEAST KANSAS MEAGER FRONTOGENETICAL AND
ISENTROPIC LIFT HAS BROUGHT SOME LIGHT SNOW...MAINLY IN THE FORM OF
NON-ACCUMULATING FLURRIES. BY MID-DAY ON TUESDAY EXPECT THE
LOW/MID LEVEL LIFT AND SATURATED CONDITIONS TO MOVE OFF THE EAST OF
THE FORECAST AREA ALLOWING A GRADUAL BREAKDOWN OF THE STRATUS DECK.
EXPECT VERY LIGHT COLD AIR ADVECTION TO PERSIST THROUGHOUT THE DAY
AS WINDS STAY FROM THE NORTH WHERE THE SURFACE HIGH WILL RESIDE. AS
A RESULT OF THE COLD AIR ADVECTION AND THE ABBREVIATED DURATION
OF CLEAR SKIES EXPECT TEMPS ON TUESDAY TO REMAIN IN THE MID TO
UPPER 20S ACROSS AREAS NORTH OF THE KANSAS TURNPIKE...WITH TEMPS
SOUTH AND EAST OF THE TURNPIKE REACHING THE LOWER 30S. FOR TUESDAY
NIGHT THE SURFACE HIGH MOVES EASTWARD AND CENTERS OVER NORTHEAST
KANSAS. EXPECT SKIES TO CLEAR OUT AND WINDS TO GO CALM OVERNIGHT.
EXPECT TUESDAY NIGHT/WED MORNING TO BE THE COLDEST PERIOD FOR THIS
FORECAST PACKAGE AS TEMPS WILL DROP TO THE LOWER TEENS ACROSS THE
ENTIRE AREA...WITH THE LOWER TERRAIN OF RIVER VALLEYS PERHAPS
DROPPING INTO THE SINGLE DIGITS. BY WEDNESDAY THE ARCTIC AIRMASS
WHICH BROUGHT THE FRIGID TEMPS FOR THE EARLY PART OF THE WEEK WILL
SHIFT EAST AND WARMER AIR WILL ADVECT INTO THE AREA...ALLOWING
WEDNESDAY`S TEMPS TO REACH THE UPPER 30S TO LOWER 40S.
MID-RANGE AND EXTENDED FORECAST (THURSDAY THROUGH MONDAY)...
FAIRLY INACTIVE WEATHER PATTERN SHAPING UP FOR THE MIDDLE TO LATE
PART OF THE WEEK AND INTO THE WEEKEND...AS NO REAL MID OR UPPER
LEVEL FORCING ENTERS THE AREA. ALTHOUGH THE DAY TIME HOURS WILL BE
SLIGHTLY WARMER FOR THE MIDDLE TO LATE PART OF THE WEEK OVERNIGHT
LOWS WILL STILL DROP TO THE MID TEENS TO UPPER 20S AS ANOTHER MASS
OF COLD AIR DIPS INTO THE AREA. PERHAPS THE ONLY WEATHER TO AFFECT
NORTHEAST KANSAS WILL BE LATE IN THE WEEK AS AN UPPER LEVEL LOW DIGS
SOUTHWARD THROUGH NEBRASKA BUT ITS SOUTHWARD PROGRESS STOPS IN
SOUTHERN NEBRASKA BEFORE IT EJECTS EASTWARD. WITH LITTLE MOISTURE
FOR THE SYSTEM TO WORK WITH EXPECT ONLY A FEW FLURRIES ACROSS AREAS
NORTH OF HIGHWAY 24 THURSDAY NIGHT/FRIDAY MORNING. THEREAFTER EXPECT
A DRY FORECAST FOR THE REST OF THE WEEK AND THROUGH THE WEEKEND WITH
DAYTIME HIGHS IN THE 40S AND OVERNIGHT LOWS IN THE UPPER 20S TO
LOWER 30S.
JL
&&
.AVIATION...
STRATUS WITH MVFR CEILINGS...AROUND 1600 FT...WERE OBSERVED AT THE TAF
SITES THIS MORNING. ISENTROPIC DOWN-GLIDE WILL INCREASE THROUGH MID
MORNING AND SHOULD SCATTER OUT THE MVFR CEILINGS BY 16Z. EXPECT
VFR CONDITIONS THROUGH THE REMAINDER OF THE TAF PERIOD. NORTH
WINDS OF 8 TO 12 KTS WILL SLOWLY DIMINISH THROUGH THE DAY.
GARGAN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
339 AM CST TUE DEC 6 2011
.DISCUSSION...
SHORT RANGE FORECAST (TODAY AND WEDNESDAY)...
8Z WATER VAPOR IMAGERY AND ASSOCIATED 500 MB RUC ANALYSIS SHOWS A
HIGHLY AMPLIFIED POSITIVELY TILTED TROUGH OVER THE CENTRAL PLAINS
WITH ITS AXIS EXTENDING FROM LAKE SUPERIOR AND RUNNING SOUTHWESTWARD
THROUGH NEBRASKA AND INTO THE FOUR CORNER REGION. CURRENTLY
TEMPERATURES ACROSS CENTRAL NEBRASKA ARE BELOW ZERO AS THE SURFACE
RIDGE OF HIGH PRESSURE IS CENTERED OVER NEBRASKA. THE COLDEST
LOCATION REMAINS KBBW WHERE THE TEMP AT 9Z WAS -11. ACROSS NORTHEAST
KANSAS TEMPERATURES REMAIN IN THE MID TEENS WITH WIND CHILLS IN THE
SINGLE DIGITS. ACROSS SOUTHEAST KANSAS MEAGER FRONTOGENETICAL AND
ISENTROPIC LIFT HAS BROUGHT SOME LIGHT SNOW...MAINLY IN THE FORM OF
NON-ACCUMULATING FLURRIES. BY MID-DAY ON TUESDAY EXPECT THE
LOW/MID LEVEL LIFT AND SATURATED CONDITIONS TO MOVE OFF THE EAST OF
THE FORECAST AREA ALLOWING A GRADUAL BREAKDOWN OF THE STRATUS DECK.
EXPECT VERY LIGHT COLD AIR ADVECTION TO PERSIST THROUGHOUT THE DAY
AS WINDS STAY FROM THE NORTH WHERE THE SURFACE HIGH WILL RESIDE. AS
A RESULT OF THE COLD AIR ADVECTION AND THE ABBREVIATED DURATION
OF CLEAR SKIES EXPECT TEMPS ON TUESDAY TO REMAIN IN THE MID TO
UPPER 20S ACROSS AREAS NORTH OF THE KANSAS TURNPIKE...WITH TEMPS
SOUTH AND EAST OF THE TURNPIKE REACHING THE LOWER 30S. FOR TUESDAY
NIGHT THE SURFACE HIGH MOVES EASTWARD AND CENTERS OVER NORTHEAST
KANSAS. EXPECT SKIES TO CLEAR OUT AND WINDS TO GO CALM OVERNIGHT.
EXPECT TUESDAY NIGHT/WED MORNING TO BE THE COLDEST PERIOD FOR THIS
FORECAST PACKAGE AS TEMPS WILL DROP TO THE LOWER TEENS ACROSS THE
ENTIRE AREA...WITH THE LOWER TERRAIN OF RIVER VALLEYS PERHAPS
DROPPING INTO THE SINGLE DIGITS. BY WEDNESDAY THE ARCTIC AIRMASS
WHICH BROUGHT THE FRIGID TEMPS FOR THE EARLY PART OF THE WEEK WILL
SHIFT EAST AND WARMER AIR WILL ADVECT INTO THE AREA...ALLOWING
WEDNESDAY`S TEMPS TO REACH THE UPPER 30S TO LOWER 40S.
MID-RANGE AND EXTENDED FORECAST (THURSDAY THROUGH MONDAY)...
FAIRLY INACTIVE WEATHER PATTERN SHAPING UP FOR THE MIDDLE TO LATE
PART OF THE WEEK AND INTO THE WEEKEND...AS NO REAL MID OR UPPER
LEVEL FORCING ENTERS THE AREA. ALTHOUGH THE DAY TIME HOURS WILL BE
SLIGHTLY WARMER FOR THE MIDDLE TO LATE PART OF THE WEEK OVERNIGHT
LOWS WILL STILL DROP TO THE MID TEENS TO UPPER 20S AS ANOTHER MASS
OF COLD AIR DIPS INTO THE AREA. PERHAPS THE ONLY WEATHER TO AFFECT
NORTHEAST KANSAS WILL BE LATE IN THE WEEK AS AN UPPER LEVEL LOW DIGS
SOUTHWARD THROUGH NEBRASKA BUT ITS SOUTHWARD PROGRESS STOPS IN
SOUTHERN NEBRASKA BEFORE IT EJECTS EASTWARD. WITH LITTLE MOISTURE
FOR THE SYSTEM TO WORK WITH EXPECT ONLY A FEW FLURRIES ACROSS AREAS
NORTH OF HIGHWAY 24 THURSDAY NIGHT/FRIDAY MORNING. THEREAFTER EXPECT
A DRY FORECAST FOR THE REST OF THE WEEK AND THROUGH THE WEEKEND WITH
DAYTIME HIGHS IN THE 40S AND OVERNIGHT LOWS IN THE UPPER 20S TO
LOWER 30S.
JL
&&
.AVIATION...
FORECAST SOUNDINGS AND SATELLITE TRENDS SUGGEST MVFR CIGS TO
REMAIN OVER THE TERMINALS THROUGH 12Z OR SO. EXPECT MHK TO BREAK
OUT EARLIER WITH TOP AND FOE TO FOLLOW AS SUBSIDENCE ERODES THE
CLOUDS BY 18Z. WINDS CONTINUE NORTH NEAR 10 KTS THEN DECREASE AS
SURFACE HIGH MOVES EAST.
53
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1020 PM MST MON DEC 5 2011
.UPDATE...
850 PM MDT MON DEC 5 2011
LATEST RUC HRRR HAS A BIT BETTER HANDLE ON COLDER TEMPS PRESENTLY
AND THROUGH THE REST OF THE OVERNIGHT REALLY TANKS TEMPS IN AREAS
SUCH AS MCCOOK AND NORTON WITH READINGS IN THE -10F TO -14F RANGE
AFTER 12Z. 00Z MET GUIDANCE FOR KMCK SHOWING -9F. KMCK DROPPED TO
-1F 2 MORNINGS AGO. HAVE UPDATED MINS TO DROP THEM TO AROUND -11F
WHILE IN NORTON HAVE LOWERED THEM TO THE -10F RANGE.
FOR NORTON COUNTY COMBINATION OF THE 10F FORECAST AND WEST WIND OF 5
MPH OR LESS PUTS THEM IN WIND CHILL ADVISORY CRITERIA. WILL CONTINUE
TO MONITOR 03Z RUN OF THE HRRR AND SEE WHAT IT DOES FOR TEMPS AND
WINDS.
007
&&
.DISCUSSION...
221 PM MST MON DEC 5 2011
EARLY AFTERNOON WV IMAGERY AND RUC H5 ANALYSIS SHOW LARGE SCALE
TROUGH EXTENDING FROM GREAT LAKES REGION...ACROSS CENTRAL
COLORADO...WITH BASE OF TROUGH OVER SOUTHERN ARIZONA/NEW MEXICO.
THROUGH TONIGHT...SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD OVER
THE CENTRAL HIGH PLAINS AS A WEAK SHORTWAVE TROUGH CONTINUES TO PUSH
AWAY FROM THE FORECAST AREA. COMBINATION OF CLEARING SKY...VERY
LIGHT WINDS AND WIDESPREAD SNOW COVER WILL CONTRIBUTE TO VERY COLD
TEMPERATURES OVERNIGHT. AMBIENT TEMPERATURES WILL FALL BELOW ZERO
FOR ALL BUT THE FAR SOUTHEAST PORTION OF THE FORECAST AREA WHICH
WILL REMAIN AT OR SLIGHTLY ABOVE ZERO. DESPITE THE LIGHT
WINDS...WIND CHILL READINGS WILL FALL TO AS LOW AS 20 BELOW ZERO FOR
A PERIOD OF TIME PRIMARILY OVER THE NORTHWEST HALF OF THE FORECAST
AREA. AS SUCH...WILL ISSUE A WIND CHILL ADVISORY.
FOLTZ
TUESDAY-WEDNESDAY...SHORTWAVE RIDGING WILL BUILD OVER THE CWA
TUESDAY QUICKLY FOLLOWED BY WESTERLY FLOW ALOFT WEDNESDAY...WHICH
WILL FAVOR DRY CONDITIONS OVER CWA. SHALLOW COLD AIR MASS WILL BEGIN
TO MODERATE...WITH HIGH/LOW TEMP FORECAST COMPLICATED BY LINGERING
SNOW PACK. CONTINUED TO UNDERCUT GUIDANCE THROUGH THESE
PERIODS....NOT EXPECTING TEMPS TO MAKE IT ABOVE FREEZING UNTIL
WED AFTERNOON.
WEDNESDAY NIGHT-THURSDAY NIGHT...COLD FRONT PUSHES SOUTH ACROSS CWA
WEDNESDAY NIGHT...WITH SHORTWAVE TROUGH PASSING NORTH OF CWA
THURSDAY/THURSDAY NIGHT. BEST LIFT/MOISTURE LOOKS TO REMAIN OVER
CENTRAL NEBRASKA...HOWEVER MODEL POINT SOUNDINGS DO SHOW DENDRITIC
LAYER BEGINNING TO SATURATE IN EXTREME NORTHERN PART OF CWA IN THE
21Z-00Z TIME FRAME. WENT AHEAD AND ADDED SLIGHT CHANCE POPS TO SW
NEBRASKA COUNTIES 18Z-00Z WHERE A DUSTING COULDNT BE RULED OUT. ALSO
EXPANDED FLURRIES FURTHER SOUTH...AND MADE CONDITIONS DRY AFTER 06Z.
FRIDAY-MONDAY...WARMING TREND WILL START UP AGAIN FRIDAY...AND
CONTINUE THROUGH THE WEEKEND WITH SHORTWAVE RIDGING ACROSS WESTERN
CONUS THROUGH SATURDAY. TEMPERATURES SHOULD MODERATE TO NEAR
NORMAL VALUES IN THE UPPER 30S/LOW 40S SAT/SUN. CLOSED LOW BEGINS
TO DEVELOP OVER SW CONUS BY SUNDAY NIGHT/MONDAY WITH W/SW FLOW
DEVELOPING OVER CWA AHEAD OF THIS FEATURE. GUIDANCE IN GENERAL
AGREEMENT ON ARRIVAL OF COLD FRONT SUN NIGHT/MON...WHICH SHOULD
SUPPORT A RETURN TO BELOW NORMAL TEMPERATURES EARLY NEXT WEEK. NOT
EXPECTING ANY PRECIP THROUGH EXTENDED PERIODS...WITH DRY AIR MASS
IN PLACE OVER CWA.
DR
&&
.AVIATION...
1020 PM MST MON DEC 5 2011
FOR THE 06Z TAFS...VFR THROUGH THE PERIOD AT BOTH KGLD AND KMCK. SFC
HIGH OVER THE AREA PRODUCING SOUTHEST WINDS OF 5 TO 10 KTS. THESE
WINDS WILL CONTINUE THROUGH THE DAY TUESDAY BEFORE BECOMING WEST
TOWARD THE END OF THE PERIOD WITH AN INCREASE IN MID LEVEL CLOUDS AS
WELL.
007
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...WIND CHILL ADVISORY UNTIL 8 AM MST /9 AM CST/ TUESDAY FOR
KSZ001>003-013-014-027.
NE...WIND CHILL ADVISORY UNTIL 8 AM MST /9 AM CST/ TUESDAY FOR
NEZ079>081.
CO...WIND CHILL ADVISORY UNTIL 8 AM MST TUESDAY FOR COZ090>092.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1113 PM CST MON DEC 5 2011
.AVIATION...
FOR THE 06Z TAF ISSUANCE.
VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGH LATE TUESDAY
AFTERNOON. SURFACE HIGH PRESSURE WILL PREVAIL ACROSS THE NORTHERN
ROCKIES LATE TONIGHT INFLUENCING NORTHERLY WINDS 5 TO 10KT THROUGH
EARLY TUESDAY MORNING. A LEE SIDE TROUGH OF LOW PRESSURE WILL
DEVELOP ACROSS EASTERN COLORADO TUESDAY MORNING TURNING WINDS
WESTERLY 5 TO 10KT BY EARLY TUESDAY AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 500 PM CST MON DEC 5 2011/
SYNOPSIS...
THE 15.12Z 250 HPA MAP CONTINUED TO SHOW A LARGE TROUGH BISECTING THE
CONUS WITH A STRONG 100 KT JET EXTENDING SOUTHWARD FROM SASKATCHEWAN
AND ACROSS MONTANA. AN EVEN FASTER JET NEAR 150 KT WAS MOVING ACROSS
SE CANADA WITH AN EXTENSION OF THIS JET, ALBEIT WEAKER WINDS, TOWARDS
KANSAS. AT 500 HPA, VERY COLD AIR OF -40 DEG C WAS OBSERVED AT KABR
WITH -30S DEG C SOUTHWARD ACROSS COLORADO. THE ARCTIC AIR AT 700 HPA
WITH TEMPERATURES AT LEAST -20 DEG C EXTENDED ACROSS THE NORTHERN PLAINS.
5 DEGREES OF COOLING WAS NOTED BETWEEN THE 00Z AND 12Z RAOB FOR KDDC
AT 850 HPA. AT THE SURFACE, ARCTIC AIR EXTENDED ACROSS THE PLAINS WITH
TEENS AND 20S DEG F CONTINUING AT 21Z ACROSS THE SUNFLOWER STATE. -SUGDEN
DISCUSSION...
DAYS 1-2...
TONIGHT:
THE VERY SHORT TERM CONCERN FOR THIS EVENING IS THE SNOW POTENTIAL ACROSS
THE CENTRAL AND SOUTHERN HALF OF THE CWFA WITH A MORE APPRECIABLE CHANCE
FOR "HEAVIER" SNOW ACROSS THE SE CWFA. THE SATELLITE WATER VAPOR CHANNEL
SHOWS A WEAK DISTURBANCE MOVING NEW MEXICO AT THE BASE OF AN UPPER LEVEL
TROUGH. A PV ANOMALY ASSOCIATED WITH THE PASSAGE OF THE UPPER LEVEL
TROUGH AND ISENTROPIC LIFT IN THE 290-295K THETA LAYER WILL PROVIDE
ENOUGH LIFT FOR SOME SNOW SHOWERS, PARTICULARLY ACROSS THE SE FA. AS
A RESULT, HAVE INCREASED POPS UP TO CHANCE AND UPPED SNOWFALL AMOUNTS
TO 0.6-1.0 INCHES TOWARDS MEDICINE LODGE. HRRR ALSO IS SHOWING SOME ACCUMULATIONS
WHICH AGREES WITH THE QPF OUTPUT FROM THE THE NAM, GFS, GEM, ECMWF,
ARW, AND NMM...WHICH ALL PAINT A LITTLE QPF IN THIS REGION. OTHERWISE,
MID AND LOW LEVEL CLOUDS WILL EVENTUALLY CLEAR TONIGHT AS THE COLD SURFACE
HIGH PRESSURE CENTER SETTLES ACROSS KANSAS AND THE TROF CONTINUES EAST.
THIS WILL RESULT IN WEAKENING OF WINDS AND ALLOW TEMPERATURES TO PLUMMET.
I HAVE -2 TO -4 DEG F TO THE NORTHWEST AND AROUND 16 DEG F SE AS THE
NW WILL HAVE WEAKER WINDS AND LESS CLOUD COVER THAN COMPARED TO THE
SE. HAVE CONTINUED THE TREND OF HIGHLIGHTING THE LOW WIND CHILL VALUES
IN THE HWO. THESE VALUES ARE NOT EXPECTED TO REACH WIND CHILL ADVISORY
CRITERIA.
TUESDAY:
HAVE ZERO POPS IN TUESDAY AS THE CWFA WILL BE ON THE BACKSIDE (SUBSIDENCE)
OF THE UPPER LEVEL TROUGH AND HIGH PRESSURE WILL CONTINUE AT THE SURFACE.
THINK THE NAM MODEL IS BEING TOO INFLUENCED BY THE SNOWFIELD ACROSS
WEST CENTRAL AND NORTHWEST KANSAS SO HAVE STEERED AWAY FROM THIS RUN.
TEMPERATURES WILL SLIGHTLY MODERATE COMPARED TO MONDAYS HIGHS AND BE
IN THE 20S DEG F. BY TOMORROW EVENING, A WEAK LEE SURFACE TROUGH WILL
DEVELOP ACROSS EASTERN COLORADO WHICH WILL TURN OUR WINDS MORE SOUTHWESTERLY
TO WESTERLY. SKIES SHOULD BE CLEAR WITH A DRY AIRMASS OVERHEAD.
WEDNESDAY:
THE DAY WILL START COLD WITH SINGLE DIGITS TO LOW TEENS DEG F DURING
THE MORNING. DURING THE DAY, THE WEAK LEE SIDE TROUGH WILL MOVE EASTWARDS
ACROSS WESTERN KANSAS USHERED BY A SHORTWAVE TROUGH MOVING ACROSS THE
NORTHERN PLAINS. THIS WILL TURN OUR WINDS MORE NORTHWESTERLY SO WE COULD
SEE SOME DOWNSLOPE CONDITIONS AND RESULT WARMER TEMPERATURES. MEX GUIDANCE
HAS KDDC IN THE 40S AND THE ECMWF IS PARTICULARLY WARM WITH MID 40S
DEG F ACROSS THE CENTRAL AND SE FA. HAVE NOT WARMED TEMPERATURES UP
TO THIS BUT DID TWEAK THEM UP HIGHER WEDNESDAY. -SUGDEN
DAYS 3-7...
A SPLIT JET STREAM IS EXPECTED TO PREVAIL ACROSS THE CONUS WITH BENIGN
WEATHER AS A RESULT THROUGH THE EXTENDED FORECAST.
WEDNESDAY NIGHT THROUGH FRIDAY:
A NORTHWEST TO SOUTHEAST ORIENTED SURFACE HIGH WILL MOVE THROUGH THE
NORTHERN PLAINS THURSDAY AS A SHORTWAVE TROUGH IN THE NORTHERN BRANCH
OF THE JET SWINGS SOUTHEASTWARD AROUND THE SOUTHERN EDGE OF THE LARGER
HUDSON BAY . ANY NORTHWEST FLOW FRONTOGENESIS AND ATTENDANT SNOW
TIED TO THIS FEATURE WILL BE NORTH AND EAST OF THE SOUTHWEST KANSAS
REGION SO NO POPS ARE IN THE FORECAST. A GLANCING BLOW OF ARCTIC AIR
WILL ONLY RESULT IN A MINIMAL IMPACT ON TEMPERATURES WITH HIGHS GENERALLY
IN THE UPPER 30S FOR BOTH THURSDAY AND FRIDAY.
SATURDAY THROUGH MONDAY:
THE NORTHERN POLAR JET WILL BE SHIFTED NORTH DURING THIS TIME FRAME
WITH VERY WEAK FLOW IN THE MID AND UPPER LEVELS OVER THE CENTRAL ROCKIES
AND GREAT PLAINS. MEANWHILE...THE SOUTHERN JET WILL REMAIN ALONG AN
AXIS FROM THE NORTHERN BAJA OF CALIFORNIA THROUGH SOUTHWEST TEXAS TO
THE GULF COAST REGION. THE DETERMINISTIC GFS AND ECMWF MODELS BOTH
SHOW A MINOR SHORTWAVE TROUGH WITHIN THE SOUTHERN JET MOVING ACROSS
SOUTHERN CALIFORNIA/NORTHERN BAJA CALIFORNIA ENTERING THE DESERT SOUTHWEST
REGION. A JET STREAM IN THE NORTHERN POLAR JET IS EXPECTED TO DIG SOUTHWARD
DOWN THE WEST COAST AROUND SUNDAY...WHICH WILL BECOME INVOLVED WITH
THE SOUTHERN JET IN SOME FASHION. INTERACTION OF SOUTHERN AND NORTHERN
BRANCHES OF THE JET IS SOMETHING THAT MODELS WILL STRUGGLE WITH AT THIS
TIME FRAME...SO THERE IS A LOT OF UNCERTAINTY GOING INTO LATE WEEKEND/EARLY
NEXT WEEK CONCERNING HOW A POTENTIAL MEAN TROUGH IN THE WEST WILL EVOLVE...AND
JUST HOW IT WILL IMPACT SOUTHWEST KANSAS WEATHER AS A RESULT. -UMSCHEID
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 8 27 10 41 / 20 0 0 0
GCK 4 24 8 39 / 10 0 0 0
EHA 6 25 9 41 / 20 0 0 0
LBL 8 27 9 41 / 20 0 0 0
HYS 7 24 9 37 / 10 0 0 0
P28 16 30 14 42 / 40 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN12/99/99
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
945 PM EST WED DEC 07 2011
...Forecast Update...
Did a minor update to account for current temperature and sky
trends. The remaining forecast is on track. Updated products have
been issued.
Dry air continues to migrate into the forecast area. Current
T/Td spreads of generally 6-9 degrees yields relative humidity
values in the 70 to low 80 percent range. Latest guidance,
particularly LAMP data, handle the current conditions well and keep
a 4-5 degree spread through the morning hours. With this T/Td spread
and westerly wind speeds in the 3-5 mph range overnight, believe it
will be difficult for fog formation. Additionally, the gusty
northwest winds this afternoon across much of the forecast area
actually aided in drying the surface a bit. At this time, the only
potential location for fog formation would be confined to the water
surfaces of rivers and lakes in the form of steam fog (also known as
evaporation fog), as this cold airmass works over slightly warmer
river/lake waters. Once again, this would be localized to very near
the water surface, if fog were to form.
&&
.Short Term (Tonight and Thursday)...
First off, snow band was not as impressive as the HRRR earlier today
made it out to be. County officials in our Lake Cumberland region
have all indicated very little snow stuck. Webcams from that area
also look mostly just wet and not white. Had some pictures with snow
from the LEX-area webcams in a brief band that went through their in
the last couple of hours, but likewise nothing has accumulated.
Surface temperatures are just too warm, in the mid 30s along with
the still wet grounds from the rain earlier in the week.
Sunshine is poking out some in cloud cover west of a KLEX to
Scottsville line. With any heating though, additional low clouds are
developing. These clouds may yet produce some scattered very light
flurries across central KY, but temperatures will not be cool enough
where these clouds are to promote lots of snow. With the cloud
cover, temperatures are holding to around 40 degrees at most.
Skies should clear out overnight as deep dry air moves into the
region. High pressure will move in south of the region, so expect a
general westerly wind through the night. Expect temperatures to fall
into the 20s areawide overnight under these clear skies. Sheltered
locations may see the low 20s.
High pressure will be centered over the Appalachians during the day
Thursday. Thus expect a southwesterly flow. Clear skies should allow
us to reach the low/mid 40s areawide, roughly 5 degrees below normal.
.Long term (Thursday night - Wednesday)...
A digging shortwave will dive from the northern plains into the
lower Great Lakes on Friday. Moisture return ahead of this system
will be limited and therefore continued to only mention flurries in
the forecast early Friday morning across southern Indiana, gradually
working eastward across north central Kentucky and the Bluegrass
through the day. Temperatures ahead of the front will likely warm
enough for just sprinkles in the late morning and afternoon. In the
morning and the evening, moisture to about 700 mb should yield
some potential for ice crystals as temps at this level will be
around -10 C. No impacts from these flurries are anticipated.
Otherwise, cold frontal boundary moves through Friday afternoon and
evening with a cold airmass lurking for the weekend. Lows Friday
night are expected to drop into the lower 20 in most spots, with a
few upper teens possible across southern Indiana and perhaps the
Bluegrass. High temperatures on Saturday will struggle, only making
it to the low and mid 30s. Saturday night will bring more
temperatures right around the 20 degree mark.
Sunday into the middle of next week, mid level flow will gradually
transition from a progressive zonal flow then try to head back toward
the classic La Nina pattern we have been seeing which would yield
southwest flow aloft with a ridge to our southeast and a developing
trough over the western CONUS. Will keep forecast through Wednesday
dry, although some signs point to another potent system tracking
into the region possibly Thursday or Friday. Although this is pretty
far out, confidence in the recent pattern supported by
teleconnections could lead to another substantial precipitation
event across the Ohio Valley. Stay tuned.
Highs through the first half of next week will gradually moderate
toward the mid 40s, with upper 40s and low 50s ahead of the next
system possible on Wednesday. Lows each night will be in the 20s,
warming to the low 30s by Wednesday morning.
&&
.Aviation (00Z TAF Issuance)...
Expect VFR conditions through the TAF period as our latest weather
system departs the region to the east. Skies will continue to clear
from west to east overnight. Additionally, dry air is filtering into
the area. The T/Td spread should be large enough to limit fog
formation overnight. Current guidance and trends in the observations
are illustrating this as well. Surface winds will become
southwesterly by morning as surface high pressure builds across the
Appalachians.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........MJP
Short Term.......RJS
Long Term........BJS
Aviation.........MJP
AREA FORECAST DISCUSSION
NWS CARIBOU ME
858 AM EST TUE DEC 6 2011
.SYNOPSIS...
A COLD FRONT WILL MOVE OFF THE COAST LATE TODAY WITH A SERIES OF WEAK
LOW PRESSURE SYSTEMS TRACKING ALONG THE FRONT TONIGHT INTO
WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE: USING HRRR MODEL WILL END PRECIPITATION FROM WEST TO EAST
ACROSS THE REGION THIS AFTERNOON. REGION WILL START OUT PRECIP
FREE THIS EVENING THEN NEXT LOW PRESSURE MOVING ALONG STATIONARY
FRONT OVER THE GULF OF MAINE WILL BRING PRECIP BACK ACROSS THE
AREA LATER TONIGHT.
A COLD FRONT IS EXPECTED TO MOVE THROUGH THE STATE DURING THE DAY
TODAY. CURRENT GUIDANCE APPEARS TO MOVE THIS FRONTAL SYSTEM TOO
FAST AND EXPECT THE FRONT TO REMAIN STATIONARY DURING THE EARLY
MORNING AS A WAVE MOVES NORTHEASTWARD ALONG THE FRONT. AFTER THE
WAVE MOVES OFF TO THE NORTHEAST THE COLD AIR SHOULD MOVE IN DURING
THE MID MORNING. HAVE USED THE NAM12 AND GFS40 TO INITIALIZE THE
POP GRIDS THEN HAVE MANUALLY ADJUSTED TO BETTER FIT THE TIMING OF
THE COLD FRONT. HAVE ALSO INCREASE THE POPS TO NEAR 100 PERCENT IN
THE VICINITY OF THE FRONT. BY LATE IN THE AFTERNOON AND EARLY
EVENING THE FRONT SHOULD BE CLEARING THE COAST. ANOTHER LOW IS
EXPECTED TO DEVELOP ALONG THE FRONT TO THE SOUTH LATER TONIGHT AND
AS A RESULT PRECIPITATION WILL SPREAD BACK INTO SOUTH TOWARDS
WEDNESDAY MORNING. HAVE USED A BLEND OF NAM12 AND GMOS FOR WIND
AND USED THE NAM12 FOR TEMPERATURE AND DEW POINT. ALSO BLENDED
NAM12 AND GFS40 FOR QPF WITH SOME MANUAL ADJUSTMENTS.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
AN INTERESTING FORECAST IN STORE FOR THIS TERM.
A SECOND WAVE OF LOW PRES IS EXPECTED TO MOVE ALONG THE STALLED
FRONTAL BOUNDARY AND PASS THROUGH THE COAST ON WEDNESDAY. DECIDED
TO USE THE SREF POPS BLENDED IN W/THE GFS FOR EARLY WEDNESDAY
WHICH SHOWED 60-80% POPS ACROSS THE NORTHERN AND EASTERN AREAS W/.
BLYR TEMPERATURES DO LOOK TO BE COLD ENOUGH ACROSS THE NORTHERN
AND NORTHWESTERN AREAS FOR ALL SNOW WHILE CENTRAL AND DOWNEAST
AREAS WILL SEE MAINLY RAIN. THE PRECIP WILL WIND DOWN BY THE
AFTERNOON W/COLDER AIR SLOWLY SEEPING SOUTHWARD. QPF IS A BLEND OF
HPC/GFS AND THE NAM WHICH SHOWS .05 TO .15". ANY SNOWFALL
ACCUMULATIONS WILL BE ACROSS THE FAR NORTH AND NORTHWEST W/UP TO
AN INCH OF ADDITIONAL ACCUMULATION. THE TEMPERATURES WERE ADJUSTED
UPWARD USING A BLEND OF THE BCGMOS AND NAM12 GIVEN THE PROXIMITY
OF THE FRONT AND HOW THE COLD AIR HAS BEEN HELD BACK THIS MORNING
AS DISCUSSED ABOVE IN NEAR TERM SECTION.
A BRIEF BREAK IN THINGS AS SOME WEAK RIDGING IS SHOWN TO WORK
ACROSS THE CWA FOR WEDNESDAY NIGHT W/SOME PARTIAL CLEARING AND
COLDER TEMPERATURES ESPECIALLY ACROSS THE NORTHERN 3RD OF THE CWA.
ONCE AGAIN, PREVIOUS MINS WERE RAISED DUE TO SLOWER PROGRESSION OF
THE COLD AIR.
NOW THE ATTENTION TURNS TO THURSDAY W/THE APCH OF LOW PRES FROM
THE MID ATLC REGION. THE 00Z RUN OF THE ECMWF ALONG THE 5 OUT 10
GFS ENSEMBLE MEMBERS SHOW THE LOW FURTHER W AND PASSING THROUGH
THE GULF OF MAINE AND THEN ACROSS NOVA SCOTIA. THE ECMWF IS THE
FURTHEST WEST BRINGING THE LOW THROUGH THE BAY OF FUNDY WHICH
WOULD MEAN A SIGNIFICANT SNOWSTORM FOR JUST ABOUT THE ENTIRE CWA.
THE 00Z RUN OF THE NAM WAS FURTHER EAST AND BRINGS THE HEAVIEST
QPF INTO THE DOWNEAST AND THE COAST. THE CANADIAN HEMISPHERIC IS
CLOSER TO THE NAM AND OPERATIONAL RUN OF THE GFS W/A TRACK ACROSS
NOVA SCOTIA. SINCE THE TRENDS HAVE BEEN A MORE WESTERN TRACK
ESPECIALLY FROM THE ECMWF AND THE GFS ENSEMBLE, CONFIDENCE IS BUILDING
TO RAISE THE BAR AND BRING LIKELY POPS INTO THE DOWNEAST AND COAST
ON THURSDAY AND CHC POPS UP INTO NORTHERN MAINE. THE CONFIDENCE
IS NOT HIGH ENOUGH THOUGH TO BRING HIGHER PERCENTAGES FURTHER
NORTH AS SHOWN BY THE ECMWF. IT WILL BE INTERESTING TO SEE HOW
THE LATER MODEL RUNS HANDLE THIS SYSTEM. TEMPERATURES DO LOOK LIKE
THEY COULD BE COLD ENOUGH FOR SNOW EVEN AS FAR SOUTH AS BANGOR AND
PERHAPS BAR HARBOR. DECIDED TO BLEND THE GMOS AND BCGMOS FOR MAX
TEMPERATURES ON THURSDAY WHICH SHOW LOW TO MID 30S.
WE WILL ADD A SECTION TO THE HWO ADDRESSING THIS POTENTIAL STORM.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE STORM SYSTEM APPEARS TO BE A FAST MOVER PULLING THROUGH THE
MARITIMES W/MUCH COLDER AIR SET TO POUR INTO THE REGION THROUGH
THE WEEKEND.
INITIALIZED THE LONGER TERM W/THE GMOS AND THEN ADJUSTED MAINLY
FOR THE POPS AND WINDS. A DISTURBANCE IS SHOWN BY THE GFS AND THE
ECMWF TO AFFECT THE CWA ON SATURDAY W/THE POSSIBILITY OF LIGHT
SNOW AND MINOR ACCUMULATIONS. AFTER THIS SYSTEM PULLS THROUGH
SATURDAY EVENING, MUCH COLDER AIR IS SHOWN TO PUSH INTO THE REGION
W/SOME OF THE COLDEST TEMPERATURES OF THE SEASON SO FAR. GMOS
TEMPERATURES LOOKED TO BE HANDLING THIS WELL AND SO NO REASON TO
DEVIATE FROM THEM. THE PRECIP CHCS LOOKED OVERDONE ON SUNDAY AND
DECIDED TO DROP THEM BACK W/HIGH PRES SHOWN TO RIDGE ACROSS THE REGION.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: EXPECT MVFR/IFR CONDITIONS TODAY AND TONIGHT.
SHORT TERM: IFR/MVFR LOOKS TO BE THE GOING RATE FOR WEDNESDAY
W/SNOW ACROSS THE NORTHERN TERMINALS ESPECIALLY KCAR AND KPQI. A
BREAK TO MVFR AND EVEN VFR POSSIBLE FOR KBGR AND KBHB WEDNESDAY
EVENING W/MVFR HOLDING FOR THE NORTHERN TERMINALS. THERE IS THE
POTENTIAL FOR CIGS AND VSBYS TO DROP BACK TO IFR AND EVEN LIFR
COME THURSDAY FOR ALL THE TAF SITES AS A STORM SYSTEM APCHS FROM
THE SOUTH.
&&
.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 FOR WINDS.
FOR WAVES USED SWAN/NAM. LONG PERIOD INCOMING WAVE APPEARS TO BE 1
FOOT OR LESS BASED ON BUOY SPECTRAL AND WNA SPECTRAL BULLETIN...SO
MOST OF COMBINED SEA RESULTING FROM LOCAL WINDS. SWAN BRING SEAS
CLOSE TO SCA AGAIN LATER TODAY. MY THINKING IS THAT WAVE HEIGHT
WILL TOP OFF JUST UNDER 5 FEET SO WILL NOT ISSUE SCA AT THIS TIME.
SHORT TERM: THERE IS POTENTIAL FOR SCA CONDITIONS ON THURSDAY INTO
THURSDAY NIGHT AS LOW PRES INTENSIFIES AS IS IT MOVES THROUGH THE
GULF OF MAINE INTO THE MARITIMES. BLENDED THE GEM/NAM12 AND GFS
FOR WEDNESDAY INTO WEDNESDAY NIGHT AND THEN FOLLOWED W/THE GFS AND
GMOS FROM THURSDAY ONWARD. THEREFORE, WINDS WERE BROUGHT UP TO 20
TO 25 KTS FOR AFOREMENTIONED TIME-FRAME AND THEN SPEEDS COME DOWN
AS HIGH PRES RIDGES IN FOR FRIDAY. WNAWAVE AND THE SWAN GUIDANCE
WAS USED FOR WAVES WHICH KEEP HEIGHTS AOB 5 FT.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...FOSTER/MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...FOSTER/MIGNONE
MARINE...FOSTER/MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1227 AM EST TUE DEC 6 2011
.SYNOPSIS...
A SLOW MOVING COLD FRONT WILL MOVE ACROSS THE STATE BY LATE
TONIGHT. THE FRONT WILL MOVE OFF THE COAST LATER TUESDAY WITH A
SERIES OF WEAK LOW PRESSURES TRACKING ALONG THE COASTAL FRONT
TUESDAY NIGHT INTO WEDNESDAY.
&&
.NEAR TERM /THROUGH TUESDAY/...
HAVE ADJUSTED TEMPERATURE...POP AND WEATHER GRIDS.
THE HRRR MODEL DOES NOT BRING THE NEXT SURGE BACK INTO NORTHERN
MAINE UNTIL EARLY THIS EVENING SO WILL START OUT WITH LOWER POPS
ACROSS THE NORTH AND THEN GRADUALLY INCREASE POPS BACK TO
CATEGORICAL THIS EVENING. AS THE COLD FRONT CROSSES NORTHERN MAINE
AFTER MIDNIGHT, RAIN WILL MIX WITH SNOW AND THEN CHANGE TO ALL
SNOW ACROSS MAINLY NORTHERN AROOSTOOK COUNTY. SNOW WILL CONTINUE
INTO THE MORNING HOURS BUT EXPECT SNOW TO BE LIGHT. AT THIS TIME
STILL EXPECTING 1 TO 3 INCHES OF SNOW ACROSS NORTHERN SECTIONS
WITH THE HIGHEST VALUES ACROSS THE ST. JOHN VALLEY.
EXPECT RAIN TO MOVE INTO CENTRAL REGIONS AFTER MIDNIGHT AND THEN
INTO DOWNEAST JUST BEFORE SUNRISE TUESDAY. RAIN WILL CONTINUE FOR
MOST OF THE DAY OVER DOWNEAST AS LOW PRESSURE MOVES ALONG THE
FRONT AS IT SLIDES OFF THE COAST.
HIGH TEMPERATURES ON TUESDAY WILL ONLY RISE 1 TO 3 DEGREES FROM
THE MORNING LOWS AS COLDER AIR MOVES IN WITH THE NORTH WINDS
BEHIND THE COLD FRONT.
FOR RAINFALL AMOUNTS EXPECTING BETWEEN A QUARTER TO HALF AN INCH
ACROSS THE REGION BY TUESDAY AFTERNOON.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY/...
THE UNSETTLED PATTERN WILL CONTINUE THROUGH THE SHORT TERM. A COLD
FRONT WILL BE STRETCHED ACROSS THE GULF OF MAINE TUESDAY NIGHT WITH
A WAVE OF LOW PRESSURE POSITIONED NEAR NOVA SCOTIA TUESDAY EVENING.
PRECIPITATION...MOSTLY IN THE FORM OF SNOW THOUGH MIXED WITH RAIN
DOWNEAST AND ESPECIALLY ALONG THE COAST... WILL BEGIN TO WIND DOWN
OVERNIGHT AS THIS LOW CONTINUES TO TREK TO THE EAST. HOWEVER ANOTHER
WEAK WAVE...THIS ONE FURTHER SOUTH...WILL KEEP AT LEAST THE SLIGHT
CHANCE OF RAIN/SNOW SHOWERS ACROSS THE REGION THROUGH WEDNESDAY
MORNING. HIGH PRESSURE WILL FINALLY BE ABLE TO TAKE HOLD WEDNESDAY
NIGHT...BUT YET ANOTHER LOW WILL MOVE TO THE SOUTH OF THE GULF OF
MAINE THURSDAY. THE 12Z ECMWF IS THE MOST AGGRESSIVE AND THE
FURTHEST NORTH WITH THIS SYSTEM AND INDICATES THAT MUCH OF DOWNEAST
MAINE WOULD SEE A RAIN/SNOW MIX. THE 12Z NAM AND GFS MEANWHILE KEEP
THE LOW SOUTH AND ONLY BRUSH THE COAST WITH PRECIPITATION. HAVE GONE
WITH SLIGHT CHANCE POPS FOR NOW. ALSO KEPT SLIGHT CHANCE POPS ACROSS
THE NORTH AS A COLD FRONT APPROACHES FROM CANADA. DAYTIME
TEMPERATURES WEDNESDAY AND THURSDAY WILL RANGE FROM THE LOWER 30S
NORTH TO AROUND 40 SOUTH WHILE THE NIGHTS DIP DOWN INTO THE 20S.&&
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
THE START OF THE LONG TERM FINDS THE GFS AND THE ECMWF WITH A
SIMILAR SOLUTION...HOWEVER THE GFS APPEARS ABOUT 6HRS BEHIND THE
ECMWF ON MOVEMENT OF THE MAIN LOW. A LOW PRESSURE (GFS) IN THE N
ATLANTIC SE OF NOVA SCOTIA...A DEEP COLD CORE LOW OVER HUDSON BAY
WITH A TROUGH EXTENDING S THROUGH THE CENTRAL GREAT LAKES REGION.
A CANADIAN HIGH PRESSURE RIDGE THAT DUG INTO THE SOUTHERN STATES
WILL BEGIN TO SPREAD TOWARDS NEW ENGLAND. THE ECMWF THE PRIMARY
LOW IS FARTHER NORTH INTO THE CANADIAN MARITIMES. AND THE BUILDING
RIDGE EXTEND FARTHER NORTH INTO SOUTHERN NEW ENGLAND. BY FRIDAY
MORNING THE HIGH MOVES INTO THE ATLANTIC... THE GFS DIGS THE
TROUGH ACROSS THE GREAT LAKE FARTHER SOUTH. THE ECMWF DEVELOPS A
WEAK LOW OVER EASTERN ILLINOIS. BY FRIDAY EVENING BOTH MODELS ARE
INDICATING A LOW OVER THE NORTHERN GREAT LAKES...WITH A TROUGH OF
LOWER PRESSURE EXTENDING SOUTH ALONG THE EASTERN SEABOARD. BY
EARLY SATURDAY MORNING BOTH MODELS MOVES THE LOW EAST...THE GFS TO
NRN MAINE...THE ECMWF TO SRN QUEBEC. BY SATURDAY MORNING THE GFS
MOVES THE LOW AND FRONT EAST OF THE AREA...THE ECMWF TO ERN MAINE.
BY SATURDAY EVENING THE LOW WILL BE WELL EAST AND A HIGH PRESSURE
RIDGE WILL BUILD IN. HIGHER PRESSURE WILL BUILD IN THROUGH THE END
OF THE PERIOD...HOWEVER THE COLD LOW OVER HUDSON BAY WILL REMAIN
THROUGH THE PERIOD AND WILL PERIODICALLY KICK OFF SHORT WAVES THAT
WILL MOVE THROUGH NORTHERN AND CENTRAL MAINE THROUGH THE END OF
THE PERIOD.
LOADED GMOS...WITH SOME HAND SMOOTHING. PLUS 15 PERCENT FOR GUST
OVER LAND 20 PERCENT OVER WATER. NAWAVE 4 FOR SEAS IN THE COASTAL
WATERS.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: VFR CONDITIONS ACROSS THE NORTH WILL LOWER TO MVFR THIS
EVENING AND THEN IFR BY LATER TONIGHT AND REMAIN IFR THROUGH
TUESDAY. VFR CONDITIONS ACROSS DOWNEAST WILL LOWER TO IFR AFTER
SUNRISE TUESDAY AND REMAIN IFR FOR THE REMAINDER OF THE DAY.
SHORT TERM: WIDESPREAD IFR IN SNOW /MIXED WITH RAIN SOUTH/
EXPECTED INTO WEDNESDAY MORNING...THEN GRADUALLY IMPROVING
CONDITIONS FROM NORTH TO SOUTH WEDNESDAY AFTERNOON AS HIGH
PRESSURE BUILDS OVER THE REGION. CLOUDS WILL INCREASE LATE
WEDNESDAY NIGHT AND THURSDAY AS A COLD FRONT APPROACHES FROM
CANADA AND A LOW PRESSURE SYSTEM MOVES TO THE SOUTH OF THE GULF OF
MAINE. THERE IS A SLIGHT CHANCE THAT THESE SYSTEMS WILL BRING SNOW
AND MVFR/IFR CONDITIONS TO THE REGION THURSDAY. MORE RAIN/SNOW IS
POSSIBLE FRIDAY AND FRIDAY NIGHT AS ANOTHER LOW MOVES ACROSS
NORTHERN MAINE.
&&
.MARINE...
NEAR TERM: WINDS AND SEAS WILL REMAIN BELOW SCA CRITERIA THROUGH
TUESDAY. A COLD FRONT WILL APPROACH FROM THE NORTH TONIGHT AND
TUESDAY AND THEN CROSS THE WATERS BY TUESDAY EVENING.
SHORT TERM: NO HEADLINES EXPECTED OVER THE WATERS AS WINDS REMAIN
BELOW 25 KT AND WAVES LESS THAN 5 FT. THE WEATHER WILL BE
UNSETTLED HOWEVER AS A SERIES OF LOW PRESSURE WAVES MOVE OVER OR
JUST TO THE SOUTH OF THE GULF OF MAINE THROUGH MID WEEK.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...MIGNONE
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
429 PM EST TUE DEC 6 2011
.SYNOPSIS...
COLDER AIR WILL ENTER THE UPPER OHIO VALLEY IN THE WAKE OF A
SLOWLY MOVING COLD FRONT. A LOW PRESSURE CENTER WILL DEEPEN OVER
THE WESTERN CAROLINAS WEDNESDAY MORNING AND CAUSE PRECIPITATION
TO LINGER LONG ENOUGH ACROSS THE MOUNTAINS, FOR RAIN TO CHANGE TO
HEAVY WET SNOW WEDNESDAY AFTERNOON INTO EARLY THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
PER RECENT SURFACE AND RADAR DATA AND HRRR AND NAM MODEL OUTPUT,
MAINTAINED SHOWERS SOUTHEAST OF PITTSBURGH THIS PERIOD. EXPECT
DRIZZLE NORTH AND WEST OF PITTSBURGH AND AREAS OF FOG ACROSS THE
MOUNTAINS OVERNIGHT.
FORECASTED LOWS USING BLEND OF GFS AND NAM MOS VALUES. MOST SPOTS
WILL REMAIN ABOVE FREEZING OVERNIGHT, AND WITH THE GROUND STILL
WARM, IT SEEMED UNLIKELY ANY OF THIS LIQUID PRECIPITATION WOULD
FREEZE.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
RECENT MODEL SUITE CONTINUES TO SHOW A LOW PRESSURE CENTER
DEEPENING OVER THE WESTERN CAROLINAS EARLY WEDNESDAY AND THEN
MOVING NORTHEAST PAST THE DELMARVA PENINSULA EARLY THURSDAY. THIS
WILL MAINTAIN PRECIPITATION ACROSS THE MOUNTAINS INTO EARLY
THURSDAY, WITH RAIN CHANGING TO SNOW DUE TO THE COOLING
TEMPERATURES.
THE PRECIPITATION, CHANGING TO SNOW, CAN BECOME HEAVY MIDDAY WEDNESDAY
INTO THE WEE HOURS OF THURSDAY ACROSS THE WV-MD MOUNTAINS. HENCE
HAVE UPGRADED THE WINTER STORM WATCH TO A WINTER STORM WARNING AS
SNOW AMOUNTS CAN EXCEED 6 INCHES. THE DENSITY OF THE SNOW CAN HAVE
THE ADDED IMPACT OF CAUSING DOWNED TREES AND POWER LINES.
COLD WEST WINDS ACROSS THE LAKE ERIE COUPLED WITH A SECONDARY COLD
FRONT MAY CAUSE SNOW SHOWERS ACROSS THE I-80 CORRIDOR THURSDAY. ISOLATED
SNOW SHOWERS CAN REDEVELOP ACROSS THE HIGHER MOUNTAINS DUE TO THE
RESULTING UPSLOPE FLOW.
PASSING HIGH PRESSURE SHOULD PROVIDE A DRY BREAK THURSDAY NIGHT
AND MOST OF FRIDAY.
FORECASTED TEMPERATURE DETAILS USING BLEND OF GFS AND NAM MOS
WHICH SHOWED VALUES ABOUT 5 DEGREES COLDER THAN NORMAL.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE MODELS ARE IN A GENERAL AGREEMENT FOR THE START OF THE LONG TERM
PERIOD WITH A WAVE DROPPING THROUGH THE GREAT LAKES SPAWNING SOME
SNOW SHOWERS ON SATURDAY AND REINFORCING THE COLD AIR ACROSS THE
REGION THROUGH THE WEEKEND.
850HPA TEMPS OF -16C ACCOMPANY THIS TROUGH SO KEPT TEMPERATURES
BELOW NORMAL FOR THE FIRST HALF OF THE LONG TERM PERIOD...
MODERATING A FEW DEGREES EACH DAY AS A RIDGE OF HIGH PRESSURE
ESTABLISHES A HOLD OVER THE EAST COAST. KEPT CLOSE TO HPC GUIDANCE
FOR THE LATTER HALF OF THE PERIOD DUE TO LOW END MODEL CONFIDENCE.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
NORTHWEST FLOW BEHIND A VERY SLOW MOVING FRONTAL BOUNDARY WILL KEEP
IFR CONDITIONS THROUGH A MAJORITY OF THE 24-30 HOUR TAF PERIOD.
SINCE BUFKIT SOUNDINGS SUGGEST THAT MANY OF THE PORTS WILL IMPROVE
TO AT LEAST LOW-END MVFR FOR A FEW HOURS THIS AFTERNOON AND UPSTREAM
OBSERVATIONS INDICATE THIS IMPROVEMENT...DECIDED TO MENTION THIS IN
MOST OF THE TAF LOCATIONS. THE SITES CLOSER TO THE FRONTAL
BOUNDARY...MGW AND LBE...MAY NOT EXPERIENCE THIS TEMPORARY
IMPROVEMENT.
CONDITIONS SHOULD DETERIORATE BACK TO IFR FOR THE REST OF THE
OVERNIGHT PERIOD INTO WEDNESDAY AS NORTHWEST FLOW AT THE SURFACE AND
SOUTHWEST FLOW ALOFT HOLD STRATUS IN PLACE. A SHORTWAVE MOVING
THROUGH THE UPPER LEVEL FLOW WILL BRING THE CHANCE FOR ADDITIONAL
SHOWERS TOMORROW.
OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...
RESTRICTIONS WILL BE POSSIBLE THROUGH WED NIGHT BEFORE HIGH PRESSURE
BUILDS IN FOR THURSDAY AND FRIDAY. NEXT CHANCE FOR RESTRICTIONS WILL
BE WITH THE SHORTWAVE PASSAGE SATURDAY. VFR WILL RETURN SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WARNING FROM 11 AM WEDNESDAY TO 4 AM EST THURSDAY
FOR MDZ001.
OH...NONE.
PA...NONE.
WV...WINTER STORM WARNING FROM 11 AM WEDNESDAY TO 4 AM EST THURSDAY
FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1106 AM EST TUE DEC 6 2011
.SYNOPSIS...
COLDER AIR WILL ENTER THE UPPER OHIO VALLEY IN THE WAKE OF A
SLOWLY MOVING COLD FRONT. PRECIPITATION WILL LINGER LONG ENOUGH
ACROSS THE MOUNTAINS FOR RAIN TO CHANGE TO SNOW WEDNESDAY INTO
EARLY THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
PER RECENT SURFACE AND RADAR DATA AND HRRR AND NAM MODEL OUTPUT,
MAINTAINED SHOWERS SOUTHEAST OF PITTSBURGH THIS PERIOD, WHILE
ADJUSTING TEMPERATURES SLIGHTLY LOWER.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
CONTINUE TO EXPECT COLDER THAN NORMAL TEMPERATURES TO SWEEP ACROSS
THE UPPER OHIO VALLEY THIS PERIOD.
HAVE MAINTAINED WINTER STORM WATCH ACROSS THE WV-MD MOUNTAINS
WEDNESDAY INTO THURSDAY. TRAILING SURFACE LOW PRESSURE CENTER
ALONG SLOW EASTBOUND COLD FRONT WILL CAUSE PRECIPITATION TO LINGER
ACROSS THE WV-MD MOUNTAINS, WHERE IT CAN CHANGE FROM RAIN TO WET
SNOW DURING WEDNESDAY.
STILL UNCERTAINTY REGARDING PRECIPITATION AMOUNTS AND
TEMPERATURES DETAILS, WHICH WILL VARY BY ELEVATION. HENCE HAVE HELD OFF
ON MORE SPECIFIC WINTER WEATHER ISSUANCES.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
ANOTHER TROUGH WILL CROSS THE AREA ON FRIDAY, SERVING TO
INSTIGATE A CHANCE OF SNOW SHOWERS THROUGH FRIDAY NIGHT AND
PROVIDE A REINFORCING SHOT OF COLD AIR. AFTERWARD, FORECAST IS
CLOSEST TO THE ECMWF ENSEMBLE MEAN. A STRONG AREA OF HIGH PRESSURE
WILL BUILD INTO THE AREA AND KEEP THE FORECAST DRY FOR THE WEEKEND
INTO MONDAY.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
EXPECT COLD NORTH TO NORTHWEST WINDS TO MAINTAIN IFR STRATUS
ACROSS MUCH OF THE UPPER OHIO VALLEY INTO AFTERNOON. THERE MAY BE
TEMPORARY IMPROVEMENT TO MVFR LATER THIS AFTERNOON.
HOWEVER, DETERIORATION BACK TO IFR IS EXPECTED TNGT AS
FRONT/POOLED MSTR IS NOT EXPECTED TO MAKE MUCH SWD PROGRESS UNDER
SWLY FLOW ALOFT.
OUTLOOK...WEDNESDAY THROUGH SATURDAY...
A SHORTWV IS FORECAST TO MOVE THRU THE SW FLOW OVR THE REGION AND
SPAWN SOME PCPN IN MGW AREA ON WED. CIG RESTRICTIONS ARE POSSIBLE
FOR MUCH OF WED AT OTHER TERMINALS. THEREAFTER...A BROAD UPR TROUGH
IS FORECAST TO DEVELOP OVR THE GREAT LAKES. PERIODIC RESTRICTIONS AND
SOME SHSN SHOULD BE ANTICIPATED IN THE COLD FLOW OVR THE REGION.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE
WEDNESDAY NIGHT FOR MDZ001.
OH...NONE.
PA...NONE.
WV...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE
WEDNESDAY NIGHT FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
625 PM EST WED DEC 7 2011
UPDATED AVIATION DISCUSSION FOR 00Z TAFS
.SYNOPSIS /ISSUED AT 354 PM/...
WV IMAGERY AND RUC ANALYSIS INDICATED CYCLONIC MID/UPPER LEVEL FLOW
AROUND A VORTEX OVER HUDSON BAY BRINGING NRN STREAM WNW FLOW FROM
SRN CANADA INTO THE UPPER GREAT LAKES. AN UPSTREAM SHORTWAVE TROUGH
WAS MOVING THROUGH SRN MANITOBA WITH ANOTHER TRAILING SHRTWV OVER
NRN SASK. AT THE SFC...WINDS WERE VEERING W TO WNW BEHIND A
TROUGH/FRONT THAT MOVED THROUGH THIS MORNING. A TRAILING ARCTIC
FRONT NEAR LAKE WINNIPEG WAS DROPPING TOWARD THE AREA WITH MUCH
COLDER AIR BEHIND IT WITH TEMPERATURES FROM -5 TO 5F OVER NORTHERN
MANITOBA/SASK. VIS LOOP INDICATED CLEARING SKIES OVER THE WEST HALF
OF THE CWA AS DRIER AIR MOVES INTO THE REGION. EVEN WITH 850 MB
TEMPS AROUND -11C...SKIES HAD CLEARED OVER MUCH OF WRN LAKE SUPERIOR.
&&
.SHORT TERM...TONIGHT AND THURSDAY
CLOUDS AND SCT LIGHT LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO
REDEVELOP OVER WRN LAKE SUPERIOR INTO WRN UPPER MI THIS EVENING AS
GREATER LOW LEVEL MOISTURE MOVES TOWARD THE AREA...PER VIS LOOP.
PASSAGE OF THE SASK SHRTWV AND ARCTIC FRONT THU MORNING WITH
INCREASING 850-700 MB MOISTURE AND INVERSION HEIGHTS CLIMBING AROUND
8K FT WILL PROVIDE A SIGNIFICANT BOOST TO THE LAKE EFFECT SNOW. SNOW
GROWTH ALSO LOOKS FAVORABLE AS THE DGZ WILL BE RIGHT IN THE BEST
OMEGA/UPWARD MOTION. GIVEN MODEL QPF AND SNOW/WATER RATIOS
APPROACHING 30/1 WOULD NOT BE SURPRISED TO SEE PERIODS OF MODERATE
TO HEAVY SNOWFALL. THE MOST PERSISTENT LOW LEVEL CONV AND CHANCE FOR
GREATEST ACCUMULATION IS EXPECTED FROM FAR NE ONTONAGON COUNTY INTO
CENTRAL HOUGHTON COUNTY...FROM GREENLAND TO TWIN LAKES. INCREASINGLY
CONVERGENT WRLY FLOW. INCREASING WINDS GUSTING TO NEAR 30 MPH AT
TIMES ON THURSDAY WILL ALSO SHARPLY REDUCE VSBYS IN BLOWING SNOW AS
WELL AND CAUSE DRIFTING SNOW ACROSS THE ROADS. SO...WITH THE
LIKELIHOOD OF AN EXTENDED PERIOD OF LES...HEAVY SNOW AT TIMES...A
LAKE EFFECT SNOW WARNING WAS ISSUED. CONFIDENCE IN ACCUMULATIONS BY
LATE THURSDAY IS LIMITED BY UNCERTAINTY ON WHERE THE HEAVIER BANDS
WILL DEVELOP AND HOW LONG THEY WILL PERSIST. SNOWFALL GENERALLY FROM
3 TO 7 INCHES IS LIKELY WITH SOME HIGHER LCL AMOUNTS.
LOCATIONS NEAR LAKE SUPERIOR EAST OF MUNISING...FROM GRAND MARAIS TO
TWO HEART MAY ALSO SEE A PERIOD OF HEAVIER LES IF THE EXPECTED
DOMINANT BAND SAGS SOUTHWARD WITH SLIGHTLY VEERING WINDS THU.
UNCERTAINTY REMAINS WHETHER THE HEAVIER SNOW WILL REMAIN OFFSHORE OR
MOVE INLAND...SO NO HEADLINES WERE ISSUED AT THIS TIME.
.LONG TERM /THURSDAY NIGHT THROUGH NEXT WEDNESDAY/...
SIGNIFICANT LAKE EFFECT SNOW IS THE MAIN CONCERN FOR THE INITIAL
PORTION OF THE LONG TERM.
LARGE SCALE TROUGH WITH COLDEST AIR OF SEASON THUS FAR TO PUSH INTO
THE AREA SETTLES OVER MUCH OF THE EASTERN CONUS TO END THE WEEK.
NOT MUCH IN THE WAY OF LARGER SCALE SHORTWAVES THAT WILL BRING
WIDESPREAD SNOW TO THE AREA...BUT SIGNIFICANT LK EFFECT FOR WEST
FLOW AREAS IS LIKELY AS H85 TEMPS TUMBLE TO AROUND -18C BY FRIDAY.
MODEL SOUNDINGS INDICATE LAKE INDUCED CAPES AOA 600J/KG WHILE LAKE
EQUIBRIUM LEVELS ARE OVR 10 KFT AGL. HIGHER OVERWATER INSTABILITY
IS SUPPLEMENTED BY STRONG LOW-LEVEL (SFC-H95) CONVERGENCE.
MODELS ARE ACTUALLY IN VERY GOOD AGREEMENT WITH OVERALL SCENARIO
THOUGH SUBTLE SHIFTS IN BLYR WINDS MAKE ALL THE DIFFERENCE AS TO
THE LOCATIONS THAT END UP WITH THE HIGHEST SNOW AMOUNTS. BY LATE
THURSDAY AND INTO THURSDAY NIGHT...SHEAR WITHIN THE SFC-H8 LAYER
IS QUITE LOW...LEADING TO BETTER CHANCE THAT DOMINANT BANDS CAN
ORGANIZE. WINDS BECOMING WESTERLY AT 925MB WITH WSW OR SW SFC WINDS
OVR UPR MI (ENHANCED BY NIGHTTIME LAND BREEZES) WOULD FAVOR STRONGEST
CONVERGENCE/HEAVIER SNOW BANDS OVR WESTERN UPR MI FM ONTONAGON
THROUGH TWIN LAKES/PAINESDALE. WARNING WILL CONTINUE FOR THOSE AREAS
THROUGH LATE FRIDAY FOR THIS PROLONGED HEAVY LAKE EFFECT SNOW EVENT.
STORM TOTALS OVER A FOOT SEEM PRETTY LIKELY IF THE PRIMARY SNOW BAND
STAYS STATIONARY FOR REASONABLE AMOUNT OF TIME.
HIGHER TERRAIN AREAS OF REST OF HOUGHTON COUNTY WILL ALSO SEE
OFF-AND-ON HEAVIER SNOW SHOWERS. ALSO EXPECT SOME HEAVIER SNOW TO
OCCUR OVR SOUTHERN PORTIONS OF HOUGHTON COUNTY...MAINLY NORTH OF
M-38. ADVY WILL COVER THIS POSSIBILITY. EXPECT VERY LITTLE IF ANY
SNOW TOWARD KENTON/SIDNAW ALONG M-28. KEWEENAW COUNTY IS MORE OF A
QUESTION MARK AS THE MORE WNW BLYR WINDS THERE ARE NOT AS FAVORABLE.
STILL THOUGH...DEGREE OF INSTABILITY AND SUFFICIENT MOISTURE PRESENT
COULD LEAD TO LOCALIZED HEAVY AMOUNTS OVR HIGHER TERRAIN THERE AS
WELL. AN ADVISORY WILL HANDLE THIS FOR NOW...THOUGH LATER UPGRADE
COULD BE NEEDED. EXPECT QUIET WEATHER FOR REST OF THE CWA THURSDAY
NIGHT INTO FRIDAY. TEMPS WILL BE ON THE CHILLY SIDE THOUGH WITH
NIGHTTIME LOWS THURSDAY NIGHT TOWARD THE ZERO MARK OVR INTERIOR SW
UPR MI AND HIGHS ON FRIDAY MAINLY STAYING IN THE TEENS.
BY LATE FRIDAY...WEAKER TROUGH FCST TO SLIDE THROUGH THE AREA MAY
VEER WINDS TO MORE NW LEADING TO INCREASED CHANCES OF LAKE EFFECT
SNOW SHOWERS INTO FAR EASTERN SECTION OF CWA...MAINLY EAST OF
MUNISING AND WELL NORTH OF NEWBERRY. LAKE EFFECT SNOW PARAMETER
DEVELOPED BY NWS GAYLORD WHICH INCORPORATES 1000-850MB
SHEAR/850-700MB RH/H85 TEMPS INDICATES FAVORABLE SETUP FOR HEAVY
SNOW RATES IN THOSE EASTERN AREAS FRIDAY AFTN/FRIDAY EVENING.
SNOWFALL RATES UP TO 2 INCHES PER HOUR COULD OCCUR IN THOSE AREAS
AND HEADLINES MAY BE NEEDED AT SOME POINT. HOWEVER...WILL LEAVE
THOSE DECISIONS TO LATER SHIFTS AS EXPECT VERY LITTLE SNOWFALL IN
THOSE AREAS THROUGH FRIDAY MORNING.
TROUGH AND COLDER AIR SFC-H85 SLOWLY HEAD INTO LOWER GREAT LAKES
FRIDAY NIGHT INTO SATURDAY. WARM AIR ADVECTION STARTS UP BY SATURDAY
LEADING TO A PUSH OF ISENTROPIC ASCENT 285-290K (750-650MB) ACROSS
MUCH OF THE CWA. UVM IN THE LAYER FAIRLY STRONG...BUT TROUBLE IS
THERE IS DRY AIR LINGERING BLO H85 THRU THE DAY. COULD BE SOME
FLURRIES OR LIGHT SNOW SHOWERS...BUT BETTER SATURATION WILL KEEP THE
GREATER CHANCE OF ACCUMULATING SNOWS MORE INTO ONTARIO. GUSTY SW
WINDS WILL ADD CHILL TO THE AIR DESPITE SFC TEMPS REBOUNDING INTO
LOWER TO MIDDLE 20S.
FOR THE EXTENDED...TROUGH THAT WAS OVER THE AREA FOR MUCH OF THIS
WEEK IS FCST TO EASE INTO EASTERN CANADA LEADING TO MORE OF A ZONAL
FLOW PATTERN/WARMING TREND BY EARLY NEXT WEEK. WEAK SHORTWAVE/WARM
FRONT SLIDES ACROSS UPR LAKES MONDAY BUT MOISTURE IS MINIMAL SO DO
NOT EXPECT A WHOLE LOT OF PRECIPITIATON. BETTER CHANCE OF
PRECIPITATION WOULD BE FARTHER NORTH CLOSER TO H85-H7 FRONTOGENESIS
AND RIGHT ENTRANCE REGION OF UPR JET OVR ONTARIO. ANOTHER TROUGH
FORMING OVR SCNTRL CANADA IS FCST TO MOVE ACROSS THE UPR GREAT LAKES
LATE TUESDAY INTO WEDNESDAY. DIFFERENCES BEGIN TO APPEAR WITH REGARD
TO DEPTH OF TROUGH BY WEDNESDAY. LAST TWO RUNS OF GFS CLOSED THE
TROUGH OFF OVR UPR MISSISSIPPI RIVER VALLEY/UPR LAKES. MEANWHILE...
RECENT RUNS OF THE ECMWF AND PREVIOUS RUNS OF GFS INDICATED MORE OF
A PROGRESSIVE SYSTEM...WITH DEEPER SYSTEM FORMING OVR CNTRL PLAINS
MID-LATE NEXT WEEK. ENSEMBLES FM GFS/ECMWF/CANADIAN SHED LITTLE
LIGHT ON THE SUBJECT WITH MIXED SIGNALS IN TERMS OF STRENGTH AND
MOVEMENT OF THE TROUGHS. DOES SEEM THAT AT LEAST ECMWF WOULD SUPPORT
BETTER CHANCE OF ORGANIZED PRECIPITATION IN THE MIDWEEK TIME FRAME.
WILL NOT PUT TOO MUCH EMPHASIS ON THIS YET THOUGH AS SUPPORT FOR
THAT IDEA REMAINS LIMITED SUPPORT LOOKING AT OTHER AVILABLE GUIDANCE
AND ENSEMBLES.
&&
.AVIATION /FOR THE 00Z TAF ISSUANCE/...
EXPECT VFR CONDITIONS THIS EVNG WITH WEAK HI PRES RDG/DRY AIR WEDGE
DOMINATING UPR MI. ARRIVAL OF THE FIRST IN A SERIES OF LO PRES TROFS
WL BRING DETERIORATING CONDITIONS TOWARD MIDNGT AT LEAST TO THE MORE
EXPOSED CMX LOCATION...WHERE LK MOISTENING/DESTABILIZATION WL BE
MORE SGNFT. THE SECOND LO PRES TROF IS DUE TO ARRIVE MID MRNG ON
THU. THIS DEEPER TROF WL BE FOLLOWED BY STRONGER W WINDS THAT WL
CAUSE GUSTS AS HI AS 30 KT OVER THE EXPOSED KEWEENAW/CMX. THE
COMBINATION OF FALLING LK EFFECT SN AND BLSN WHIPPED UP BY THESE
STRONG WINDS WL LIKELY LEAD TO LIFR CONDITIONS AT THAT SITE. THE DRY
NATURE OF THE ARCTIC AIRMASSES WL LIMIT DETERIORATION AT IWD AND
ESPECIALLY SAW...WHERE THE PREVAILING WLY WIND COMPONENT WL
DOWNSLOPE/DRY AND RESULT IN PREDOMINANT VFR CONDITIONS.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
WINDS MAINLY OUT OF A WESTERLY DIRECTION OVER 20KTS WILL PREVAIL
THROUGH MUCH OF THE PERIOD. THE WINDS/WAVES ALONG WITH PLENTY OF
COLD AIR WILL RESULT IN THE POTENTIAL FOR FREEZING SPRAY TONIGHT
INTO FRIDAY. WESTERLY GALES ARE EXPECTED TO RETURN AROUND SUNRISE
THURSDAY BEHIND AN ARCTIC FRONT OVER THE WEST HALF...BEFORE
EXTENDING THROUGH CENTRAL AND EASTERN LS THROUGH EARLY THURSDAY
EVENING.
EXPECT STRONG HIGH PRESSURE ACROSS SW CANADA TO WEAKEN ACROSS THE
PLAINS STATES FRIDAY...WHILE EXTENDING A RIDGE ACROSS LS BY FRIDAY
NIGHT. LOW PRESSURE OVER MANITOBA SATURDAY MORNING WILL SLIDE ACROSS
ONTARIO SATURDAY AFTERNOON AND EVENING...WHILE DRAGGING A TROUGH
OVER LS. A PERIOD OF SW GALES IS POSSIBLE SATURDAY AHEAD OF THE LOW.
ANOTHER LOW PRESSURE SYSTEM...OVER THE DAKOTAS SUNDAY MORNING...WILL
LIKELY FILTER ACROSS LAKE SUPERIOR SUNDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING FROM 1 AM THURSDAY TO 7 PM EST FRIDAY
FOR MIZ002-003.
LAKE EFFECT SNOW ADVISORY FROM 1 AM THURSDAY TO 7 PM EST FRIDAY
FOR MIZ001-084.
LAKE SUPERIOR...
GALE WARNING FROM 7 AM THURSDAY TO 1 AM EST FRIDAY FOR
LSZ263>267.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
415 PM EST TUE DEC 6 2011
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A SHEARED MID/UPPER LEVEL
TROUGH FROM NRN ONTARIO THROUGH NW WI AND IA INTO THE CNTRL PLAINS.
AN UPSTREAM SHORTWAVE TROUGH WAS MOVING THROUGH CNTRL MANITOBA. AT
THE SFC...SW FLOW WAS INCREASING OVER WRN LAKE SUPERIOR AND W UPPER
MI BTWN A DEPARTING RIDGE FROM QUEBEC INTO EAST UPPER MI AND A
TROUGH OVER MANITOBA. ALTHOUGH THE BACKING WINDS HAVE PUSHED THE
LAKE CLOUDS OFFSHORE OVER THE CNTRL AND WEST CWA...LOWER LEVEL
MOISTURE OVER WRN WI WAS STREAMING BACK INTO THE WEST...PER VIS
LOOP. MID LEVEL CLOUDS WERE ADVANCING THROUGH NW ONTARIO AND NRN MN
ASSOCIATED WITH WAA/295K ISENTROPIC LIFT AHEAD OF THE TROUGH.
&&
.SHORT TERM...TONIGHT AND WEDNESDAY
MAIN FCST CONCERN IS LES POTENTIAL WITH THE FRONT/TROUGH MOVING
THROUGH THE AREA.
SATELLITE TRENDS AND NAM/RUC 925-900 MB RH FCST SUGGESTS THAT THE
LOWER CLOUDS WILL CONTINUE TO SPREAD TO THE EAST THIS EVENING AND
THEN MOVE OUT OVERNIGHT AS WINDS BEGIN TO VEER MORE TO THE WNW.
MODERATE MID LEVEL QVECTOR CONV ASSOCIATED WITH THE TROUGH MOVING
INTO THE AREA WED MORNING WILL BRING AN INCREASE IN 850-700 MB
MOISTURE. WITH WINDS VEERING WRLY AND 850 MB TEMPS TO AROUND
-11C...CONDITIONS WILL BECOME MORE FAVORABLE FOR LES INTO THE
KEWEENAW LATE TONIGHT INTO WED MORNING. CAA DROPS 850 MB TEMPS TO
AROUND -14C DURING THE AFTERNOON...BUT THE DEEPER MOISTURE IS
EXPECTED TO DEPART. SINCE THE PERIOD WITH THE COMBINATION OF LOW
LEVEL CONV AND 850-700 MB MOISTURE IS BRIEF...ANY LES
ACCUMULATIONS ARE EXPECTED TO BE LIGHT...GENERALLY AN INCH OR LESS.
SCT -SHSN WILL ALSO AFFECT LOCATIONS E OF MUNISING DURING THE
AFTERNOON BUT AGAIN ACCUMULATIONS SHOULD BE LIGHT.
.LONG TERM /WED NIGHT THROUGH NEXT TUESDAY/...
COLD FRONT THAT WILL START THE COOLING TREND WILL BE EAST OF THE
AREA AT THE START OF THE PERIOD...WHICH WILL PRODUCED A PROLONGED
LAKE EFFECT SNOW PERIOD FOR PORTIONS OF UPPER MICHIGAN.
EXPECT SFC LOW TO BE STATIONED OVER HUDSON BAY THROUGH SAT...WHILE A
SFC HIGH SHIFTS FROM THE NRN PLAINS ON THURS TO THE OHIO RIVER
VALLEY BY FRI NIGHT. THIS WILL LEAD TO WINDS OUT OF A WNW DIRECTION
ON WED NIGHT INTO THURS...THEN BACKING TO THE W FOR THURS NIGHT INTO
FRI NIGHT. THIS A LITTLE MORE WESTERLY THAN SHOWN YESTERDAY AND WILL
LIKELY FOCUS PCPN OVER THE ERN CWA TO BE FROM GRAND MARAIS
EASTWARD...RIGHT ALONG THE SHORELINE. THINK LAND BREEZES WILL HELP
FOCUS A DOMINATE BAND EITHER RIGHT ALONG THE SHORELINE OR JUST
OFFSHORE AT TIMES DURING THE PERIOD. OVER THE WEST...FAVORABLE
LOCATIONS WILL BE FROM ROCKLAND THROUGH COPPER HARBOR...ESPECIALLY
OVER THE HIGHER TERRAIN.
EXPECT LES TO BE ONGOING AT THE START OF THE PERIOD...BUT WILL
REALLY BEGIN TO RAMP UP OVERNIGHT WED INTO THURS MORNING...AS
SHORTWAVE AND SECONDARY SFC TROUGH SWEEP ACROSS THE AREA. THIS WILL
INCREASE MID LVL MOISTURE AND START A DOWNWARD TREND IN H850 TEMPS
FROM -14C /DELTA-T OF 19/ TO -20C OVER THE W AND -18C OVER THE E.
THESE VALUES DON/T LOOK AS COLD AS YESTERDAY FOR THE THURS/FRI TIME
FRAME...WHICH WILL BE MORE FAVORABLE FOR THE LES POTENTIAL...AS THE
DGZ WILL BE RIGHT IN THE BEST OMEGA. IN ADDITION...MODELS SHOWING A
MORE MOIST LLVL...WITH LESS SUB CLOUD LAYER DRY AIR. THIS ALLOWS THE
BEST LK INDUCED FORCING TO BE LOCATED DIRECTLY IN OR THE TOP HALF OF
THE DGZ AND AID FOR FASTER ACCUMULATION. THUS...HAVE BUMPED UP SLR
UP SLIGHTLY INTO THE LOW/MID 20S...ALTHOUGH NOT QUITE AS HIGH AS
SEEN ON SOME OF THE CARIBOU SLR VALUES.
MIGHT BE A LITTLE LULL IN LES OVER THE WEST ON THURS AFTN...AS DRIER
AIR ABOVE H800 MOVES THROUGH AND LOWERS THE INVERSION HEIGHTS. THIS
WILL BE SHORT LIVED AS NEXT WAVE OF DEEPER MOISTURE MOVES IN AND
INVERSION HEIGHTS RISE ON THURS NIGHT WITH THE UPPER TROUGH MOVING
OVERHEAD. EVEN WITH THIS LULL...THERE WILL STILL BE GUSTY WINDS THAT
WILL CREATE BLOWING/DRIFTING SNOW ALONG THE LK SUPERIOR SHORELINE
WITH THE FAIRLY FLUFFY SNOW THAT WILL HAVE FALLEN WED NIGHT INTO
THURS MORNING.
FRI DEEPER MOISTURE STARTS TO DEPART THE WEST DURING THE
DAY...STARTING TO DIMINISH LES INSTENSITY...BUT WILL STILL BE
ONGOING THROUGH FRI NIGHT. WITH WINDS SHIFTING MORE OUT OF THE
WSW...EXPECT BEST BANDS TO BE OVER THE KEWEENAW AND OFFSHORE OVER
THE E /ALTHOUGH A WEAK TROUGH COULD SLIDE THE BAND BACK ONSHORE FRI
NIGHT/.
AS FOR SNOWFALL AMOUNTS...LES PARAMETER EXCEEDS 2 FOR MUCH OF THE
PERIOD...WHICH ALONG WITH LK INDUCED CAPE VALUES EXCEEDING 700 J/KG
AND EQL/S IN THE 9-12KFT RANGE...THE POTENTIAL IS THERE FOR HEAVY
SNOWFALL ACCUMULATIONS. CURRENT FCST FROM 6Z THURS TO 6Z SAT HAS
12-20 INCHES OVER THE HIGHER TERRAIN FROM ROCKLAND TO CALUMET AND
SIMILAR TOTALS RIGHT ALONG THE LK SUPERIOR SHORELINE E OF GRAND
MARAIS. WILL LIKELY SEE A COUPLE PERIODS WHERE OUR 8IN/12HR WARN
CRITERIA WILL BE REACHED OVER THE WEST...SO HAVE PUT OUT A LES WATCH
FOR ONTONAGON THROUGH KEWEENAW COUNTIES. HAVE LIMITED CONFIDENCE IN
THE EAST WITH BAND LOCATION DUE TO THE LITTLE MORE WRLY WINDS AND
SOME LIKELY WANDERING OF THE BAND ON/OFF SHORE THROUGH THE
PERIOD...SO HELD OFF ON A WATCH FOR TIME BEING.
DAYS 4 THROUGH 7 /FRI NIGHT THROUGH NEXT TUESDAY/...
EXPECT LES TO COME TO AN END ON SAT...AS A CLIPPER SYSTEM DROPS
THROUGH SOUTHERN ONTARIO AND SHIFTS WINDS TO THE SW AND PRODUCES WAA
ALOFT. FINE DETAILS BECOME A LITTLE MORE MUDDLED FOR SUN THROUGH
TUES...AS NO MAJOR DISTURBANCES OR FEATURES AFFECT THE REGION. THIS
LEAVES THE AREA UNDER ZONAL FLOW ALOFT FOR SUN...AHEAD OF A
SHORTWAVE MOVING ACROSS THE AREA MON INTO MON NIGHT. WITH H850 TEMPS
AROUND -1C ON SUN...EXPECT TEMPS TO BE SLIGHTLY ABOVE NORMAL WITH
HIGHS IN THE LOWER 30S. SUN NIGHT INTO MON NIGHT SHOULD SEE A SFC
TROUGH NEAR THE UPPER GREAT LKS REGION...BUT WITH HOW WEAK IT
APPEARS TO BE WITH THE ZONAL FLOW...HAVE LIMITED CONFIDENCE ON PCPN.
THUS...WILL GO WITH A MOSTLY CLOUDY PERIOD...ALTHOUGH THE BEST
CHANCE FOR PCPN WILL BE MON INTO MON NIGHT. THESE CLOUDS WILL KEEP
OVERNIGHT LOWS FROM BEING TOO COLD AND KEEP TEMPS NEAR NORMAL FOR
MON INTO TUES.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/
ANY LEFTOVER MVFR CIGS WITH LAKE EFFECT CLOUDS ARE EXPECTED TO MOVE
OUT BY MID TO LATE AFTERNOON AS WINDS BACK TO THE SW. SW GRADIENT
WINDS INCREASING THIS EVENING AHEAD OF APPROACHING COLD FRONT WILL
SUPPORT LLWS AT ALL TAF SITES TONIGHT. WINDS VEERING WRLY LATE
TONIGHT BEHIND THE FRONT SHOULD BRING MVFR CIGS BACK INTO KIWD AND
KCMX. FAVORABLE WRLY FLOW AT KCMX MAY RESULT IN WIND GUSTS AOA 30
KTS AS WELL AS POSSIBLE LAKE EFFECT SNOW SHOWERS.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
SW WINDS ARE EXPECTED TO INCREASE TO GALE FORCE TONIGHT INTO EARLY
WED...MAINLY OVER WESTERN AND NCNTRL LAKE SUPERIOR AHEAD OF A TROUGH
MOVING TOWARD THE REGION. AS WINDS VEER NW BEHIND THE TROUGH...WINDS
ARE EXPECTED TO DIMINISH INTO THE 20-30 KT RANGE. A WINTRY PATTERN
OF W-NW WINDS WILL THEN PERSIST THRU LATE WEEK WITH LAKE EFFECT SNOW
SHOWERS. GIVEN ARCTIC AIR PASSING OVER THE LAKE AND EFFICIENT
MIXING...EXPECT WINDS CONSISTENTLY 20-30 KT WITH ANOTHER PERIOD OF
GALES POSSIBLE AGAIN LATE WED NIGHT AND THURSDAY. COMBINATION OF
ARCTIC AIR AND STRONG WIND SHOULD RESULT IN FREEZING SPRAY WED NIGHT
INTO FRIDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WATCH FROM LATE WEDNESDAY NIGHT THROUGH LATE
FRIDAY NIGHT FOR MIZ001>003.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LSZ266.
GALE WARNING UNTIL 7 AM EST /6 AM CST/ WEDNESDAY FOR LSZ162.
GALE WARNING UNTIL 10 AM EST WEDNESDAY FOR LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION...UPDATED FOR 06Z TAFS
NWS MARQUETTE MI
1118 PM EST MON DEC 5 2011
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
HUDSON BAY AND NRN ONTARIO THROUGH THE NRN PLAINS TO THE SRN
ROCKIES. LITTLE LOW OR MID LEVEL FORCING WAS ASSOCIATED WITH
THE TROUGH IN THE VERY DRY AIRMASS UPSTREAM. AT THE SFC...A RIDGE
EXTENDED FROM NRN ONTARIO INTO THE NRN PLAINS RESULTING IN WEAK NRLY
LOW LEVEL FLOW ACROSS LAKE SUPERIOR INTO UPPER MI. RADAR INDICATED
LIGHT DISORGANIZED LES INTO UPPER MI. ACYC FLOW INTO THE REGION AND
SHEAR WITHIN THE SFC-850 MB LAYER HAS LIMITED INTENSITY WITH
GENERALLY LIGHT ACCUMULATIONS OF AN INCH OR LESS OBSERVED IN WEST
AND NORTH CENTRAL UPPER MI. SNOW RATIO HAS BEEN HIGH...TYPICAL OF
MOST LES...WITH THE CLOUD LAYER IN THE 2K-6K FT DGZ.
&&
.SHORT TERM...TONIGHT AND TUESDAY
SOME INCREASE IN LES INTENSITY MAY BE POSSIBLE THIS EVENING AS THE
MID LEVEL TROUGH MOVES INTO THE AREA AND 850 MB TEMPS DROP SLIGHTLY
TO NEAR -15C. HOWEVER...THE CBL FLOW WILL ALSO BECOME INCREASINGLY
ANTICYCLONIC AS THE SFC RIDGE AXIS SHIFTS OVER THE AREA. THIS WILL
ALLOW THE WINDS TO BACK OVERNIGHT WHICH WILL SHIFT THE BEST SNOWFALL
BY MORNING TO THE ONTONAGON TO THE KEWEENAW AS WELL AS ALGER COUNTY.
DESPITE THE FAVORABLE INSTABILITY AND MOISTURE...THE SHEAR COMBINED
WITH THE SHIFTING NATURE OF THE BANDS SHOULD LIMIT SNOWFALL TO 1-2
INCHES...MAINLY FROM IWD-CMX AND FROM MQT-P53. THE LIGHT WINDS MAY
ALLOW THE DEVELOPMENT OF A BAND ALONG THE SHORELINE INTO THE WEST
ANE NEAR MARQUETTE AS THE LAND BREEZE STRENGTHENS...PER
HIGH RES WRF/ARW BUT CONFIDENCE IN DETAILS FOR LES BAND EVOLUTION
IN THE LIGHT WIND REGIME IS LOW. A BRIEF PERIOD OF HEAVIER SNOW
WOULD BE POSSIBLE IF SUCH A BAND DEVELOPS.
ANY LES ACROSS THE KEWEENAW AND EAST OF MARQUETTE SHOULD RAPIDLY
SHIFT OFFSHORE ON TUESDAY AS THE RIDGE AXIS MOVES SOUTHEAST.
CONDITIONS SHOULD BE MORE PLEASANT BY AFTERNOON WITH SOME SUNSHINE
OVER THE AREA ALONG WITH RELATIVELY LIGHT SW WINDS.
.LONG TERM /TUES NIGHT THROUGH NEXT MONDAY/...
AT THE START OF THE PERIOD...AN ELONGATED UPPER TROUGH WILL BE
STRETCHING FROM JAMES BAY TO THE SRN PLAINS AND QUICKLY SHIFTING E
OF THE AREA. THIS WILL ALLOW A WEAK RIDGE...AHEAD OF THE MAIN UPPER
LOW TO AFFECT THE AREA DURING THE LONG TERM OVER THE NW TERRITORIES
OF CANADA. THIS WEAK UPPER RIDGE WILL CAUSE SFC RIDGE TO SLIDE E
ACROSS THE CWA TUES EVENING.
MIGHT SEE A QUICK COOL DOWN TUES EVENING WITH THE CLEAR SKIES AND
LIGHT WINDS...ESPECIALLY OVER THE CNTRL/ERN CWA...BUT INCREASING
SWRLY FLOW AND MID LEVEL CLOUDS AHEAD OF THE NEXT FRONT WILL LEVEL
TEMPS OFF AND MAY EVEN CAUSE THEM TO RISE SOME OVER THE WRN CWA.
WITH THE DEEPER MOISTURE AND H850-700 Q-VECTOR CONV ARRIVING LATE
TUES NIGHT...COULD SEE A FEW SNOW SHOWERS LATE TUES NIGHT OVER THE
KEWEENAW. BUT WITH THE BEST FORCING/MOISTURE OVER NRN LK
SUPERIOR...WILL KEEP THE CHANCES THERE. STRONGER PRESSURE GRADIENT
AHEAD OF THE FRONT WILL LIKELY LEAD TO SOME GALES OVER LK SUPERIOR
TUES NIGHT. EVEN WITH THE WAA ALOFT...LLVL WINDS BELOW THE INVERSION
LOOK TO BE IN THE 30-40KT RANGE AND WILL LIKELY ALSO LEAD TO A GUSTY
OVERNIGHT FOR THE HIGHER TERRAIN OF KEWEENAW PENINSULA. WILL
CONTINUE THE GALE WATCH OVER W/CNTRL LK SUPERIOR.
COLD FRONT MOVING THROUGH ON WED AND WILL USHER IN THE COLDEST AIR
OF THE SEASON. EXPECT THE MID LVL FORCING/MOISTURE TO BE THROUGH THE
AREA BY WED AFTN...AND WILL MOVE UP THE POP TIMING FROM THE PREVIOUS
SHIFT TO BE MORE IN THE MORNING FROM THE AFTN. MAY TAKE A LITTLE
WHILE FOR THE LES TO GET GOING BEHIND THE FRONT...AS INVERSION
HEIGHTS FALL TO 4.5-5.5KFT AND LLVL DRY AIR LIMITS ANY POTENTIAL
CLOUD DEPTH. THUS...WILL GO WITH SLIGHTS OVER THE WNW WIND FAVORED
LOCATIONS OVER THE WEST AND KEEP CHANCES OVER THE EAST WHERE THE
LOW-MID LVL MOISTURE WILL TRY TO LINGER LONGER. THINK THESE LIMITED
CONDITIONS WILL CONTINUE INTO THE EVENING HOURS BEFORE REALLY
INTENSIFYING THROUGH THE NIGHT.
THIS INTENSIFICATION WILL LARGELY BE DUE TO A SHORTWAVE MOVING
THROUGH ON WED NIGHT...WHICH WILL INCREASE THE LOW-MID LVL MOISTURE
AND PULL EVEN COLDER H850 TEMPS OVER THE AREA /STEADILY FALLING TO
NEAR -20C BY THURS EVENING/. THIS WILL INCREASE DELTA-T/S TO SOME
FAIRLY IMPRESSIVE VALUES /LOW-MID 20S BY THURS EVENING/. IN
ADDITION...WITH INVERSION HEIGHTS RISING TO 7-10KFT AND LK INDUCED
CAPES IN THE 500-700 J/KG RANGE...LOOKS TO BE A GOOD POTENTIAL FOR
AREAS TO RECEIVE MOD/HEAVY LES LATE WED NIGHT INTO THURS. LAKE
EFFECT SNOW PARAMATER SUPPORTS THIS POTENTIAL...RISING ABOVE
2...WHICH SUPPORTS A HIGH POTENTIAL FOR HEAVY SNOWFALL RATES...OVER
THE W WED NIGHT AND THE E ON THURS. WINDS LOOK TO BE OUT OF THE WNW
WED NIGHT INTO THURS...SO HAVE THE HIGHEST POPS IN THOSE FAVORED
LOCATIONS. ONE ITEM TO NOTE ON WIND DIRECTIONS IS THAT THE NAM/GEM
HINTING AT A MESO LOW FORMING OVER ERN LK SUPERIOR ON THURS...WHICH
COULD END UP FORCING WINDS MORE TO THE NW OVER THE WRN CWA. OVER THE
E...THIS COULD CAUSE A DOMINATE BAND TO SETUP SOMEWHERE OVER THE
SERN LAKE...POTENTIALLY RIGHT ALONG THE SHORELINE E OF GRAND MARAIS
DUE TO THE WSW WINDS AROUND THE MESO LOW. FINALLY...COULD BE A
SLIGHT LULL OVER THE W IN THE AFTN...AS SLIGHTLY DRIER AIR MOVES
THROUGH...AND HAVE SLIGHTLY LOWERED POPS FOR THAT TIMEFRAME.
DAYS 4 THROUGH 7 /THURS NIGHT THROUGH NEXT MONDAY/...
ARCTIC TROUGH DROPPING SE ACROSS THE AREA THURS NIGHT INTO SAT WILL
PROVIDE REINFORCING COLD AIR TO THE AREA AND CONTINUE THE LES.
EXPECT THE -16 TO -20C H850 TEMPS TO CONTINUE THURS NIGHT INTO FRI
NIGHT AS BL WINDS ARE FROM THE WNW THURS NIGHT INTO FRI AND THEN
START TO SHIFT TO THE WSW FRI NIGHT. WITH THE ABUNDANT LOW-MID LVL
MOISTURE UNDER THE UPPER TROUGH...THE INGREDIENTS ARE COMING
TOGETHER FOR A POTENTIALLY SIGNIFICANT LES PERIOD THURS NIGHT INTO
FRI FOR WNW WIND FAVORED LOCATIONS. AS MENTIONED PREVIOUSLY...LES
PARAMETER CONTINUES TO HIGHLIGHT THE HEAVY SNOW POTENTIAL...VALUES
ABOVE 2...THROUGH FRI FOR WNW WIND LOCATIONS. THIS IS ALSO SEEN IN
BUFKIT LK INDUCED CAPE VALUES EXCEEDING 700 J/KG AND EQL LVLS
BETWEEN 7-10KFT. IT IS A WAYS OUT...BUT BUFKIT SOUNDINGS ARE SHOWING
THE CLOUD BASES TO BE AT OR ABOVE THE DGZ AND LIMIT DENDRITES.
EITHER WAY...SHOULD SEE A HIGH SLR VALUE AND ALLOW FOR EASY
BLOWING/DRIFTING FOR AREAS NEAR LK SUPERIOR WHERE THE WINDS WILL BE
STRONGEST. IN ADDITION...THIS DRIER AIR IN THE LLVLS COULD ALSO LEAD
TO A COUPLE MAIN/DOMINATE BANDS. WILL STICK TO OUR LES CLIMO POP/SKY
GRIDS FOR THIS TIME FRAME AND WILL CONTINUE TO MENTION THE HEAVY
SNOW POTENTIAL IN THE HWO. WITH THE WINDS SHIFTING TO THE SW AND WAA
DEVELOPING ON SAT...EXPECT THE LES TO DIMINISH. THIS WAA IS DUE TO A
WEAK SHORTWAVE AND CLIPPER SYSTEM SLIDES THROUGH SOUTHERN
ONTARIO...WITH THE MAIN ENERGY/MOISTURE STAYING N OF THE CWA.
UPPER FLOW TRANSITIONS TO MORE ZONAL NRN STREAM ALONG THE
U.S./CANADA BORDER FOR SUN INTO MON. THIS ALLOWS WARMER H850
TEMPS...AROUND -1 TO 1C...TO MOVE OVER THE AREA AND LEAD TO A PERIOD
OF SLIGHTLY ABOVE NORMAL TEMPERATURES WITH HIGHS IN THE UPPER 20S
AND LOWER 30S. MODELS CONSISTENT ON SFC TROUGH SETTLING OVER THE
AREA SUN NIGHT INTO MON...AS SFC HIGHS ARE SETUP OVER THE NRN PLAINS
AND OHIO VALLEY. LIMITED UPPER LVL FORCING...SO HAVE KEPT THE FCST
DRY FOR NOW.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/
FOR EARLY IN THIS FCST PERIOD...WEATHER AT TAF SITES WILL BE
DOMINATED BY LAKE EFFECT CLOUDS/SNOW SHOWERS WITH PREDOMINANT MVFR
CIGS. AS IS TYPICAL FOR LAKE EFFECT SNOW SHOWERS...VSBY WILL BE
QUITE VARIABLE...GENERALLY RANGING FROM MVFR TONIGHT. SOME
IMPROVEMENT IN VIS IS EXPECTED TUE MORNING AS WINDS BACK MORE WNW
AHEAD OF BUILDING HIGH PRES RDG DIMINISHING SHSN. VFR CONDITIONS
WILL OCCUR IN THE LATE MORNING TO EARLY AFTERNOON AT ALL SITES.
COULD BE SOME STRONGER WINDS AND LLWS IN THE LATER PERIODS AT ALL
SITES...BUT THAT IS WAY OUT THERE AND CONFIDENCE IN PUTTING IT INTO
FORECAST IS PRETTY LOW AT THIS TIME.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
EXPECT WINDS MOSTLY IN THE 10-20 KT RANGE INTO TUE MORNING AS A HIGH
PRES RIDGE OVER NORTHERN ONTARIO AND THE NRN PLAINS SLOWLY BUILDS
ACROSS LAKE SUPERIOR. AS THE RIDGE SLIPS SE OF THE LAKE AND A COLD
FRONT APPROACHES...SW WINDS ARE EXPECTED TO INCREASE TO GALE FORCE
TUE NIGHT INTO EARLY WED...MAINLY OVER WESTERN AND NCNTRL LAKE
SUPERIOR. A WINTRY PATTERN OF W-NW WINDS WILL THEN PERSIST THRU LATE
WEEK WITH LAKE EFFECT SNOW SHOWERS. GIVEN ARCTIC AIR PASSING OVER
THE LAKE...EFFICIENT MIXING WITH 20-30 KT AND SOME GALE FORCE GUSTS
AT TIMES LATE IN THE WEEK. WITH ARCTIC AIRMASS INTO THE AREA SOME
FREEZING SPRAY MAY ALSO DEVELOP.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 7 PM TUESDAY TO 10 AM EST WEDNESDAY FOR LSZ266.
GALE WARNING FROM 5 PM EST /4 PM CST/ TUESDAY TO 7 AM EST / 6 AM
CST WEDNESDAY FOR LSZ162.
GALE WATCH FROM 5 PM EST TUESDAY TO 10 AM EST WEDNESDAY FOR
LSZ263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
357 AM CST Tue Dec 6 2011
.DISCUSSION...
Water vapor imagery early this morning shows us that Kansas and
Missouri remain under the direct influence of a large, positively
tilled and shearing, trough. It is evident that a dry wedge, that
rotated under the base of the trough early Monday, has quickly
stretched northeast, effectively detaching the moisture feed of the
Pineapple Express from much of the dynamics of the slowly shearing
trough. Which, is not to say moisture isn`t available, just that there
will be less to work with in the coming days. Otherwise, of note is a
subtle shortwave that has rounded the base of the trough, and is
heading towards central Missouri via south central Kansas. Light snow
has been observed with this features in Wichita, with a few tenths of
an inch of accumulation this morning.
For today, of primary concern is the shortwave and potential for
snow. Upper air sounding from Monday evening in Topeka shows a nice
dry layer between 900mb and 700mb, which any snow will have to
overcome in order to reach the surface. But, a variety of models
advertise that this should not be much of a problem as the top-down
seeder-feeder process gets to work as the shortwave moves through
central Missouri this morning. Current snow observations noted at
Wichita, and now Springfield and Columbia, back this idea up. Still,
lack of quality deep layer moisture, and the limited residency time
of the shortwave, should limit accumulations to something around or
under one inch. As for location, best potential for any
accumulation looks to be along a line from Clinton northeast through
Moberly, where the shearing vorticity axis of the shortwave is
expected to traverse. Some flurries will be possible father north and
west, think Kansas City to Bethany line. Have continued to highlight
snow across central Missouri by inserting likely POPs for this
morning.
After todays fleeting snow flakes stop falling, our next potential
shot at snow will arrive across the Missouri-Iowa border Thursday
night. The longwave polar low, currently in the process of shifting
across northern Canada towards the Hudson Bay, will send another
reinforcing cold shot of air south into the Plains States starting
Wednesday, which will insure that temperatures stay well below normal
through the remainder of the work week. However, looking at Thursday
nights precipitation potential, the entrance region to the jet
streak rounding the base of the mean trough, carved out by the polar
low across the central plains, would be coincident with enough
moisture to squeeze some flakes out along the Iowa border.
As for the weekend, currently it looks dry, and like a warming trend
will prevail, though we will only be warming back to around normal.
As Saturday arrives a ridge across the west coast will be shifting
farther east. This should allow for temperatures to moderate a bit
through the weekend as synoptic level height gains, and a modest south
wind on the back side of a surface high to our east, take the edge
off the cold temperatures.
CUTTER
&&
.AVIATION...
For the 06Z TAFs, MVFR cigs are likely to persist through the night
and probably Tuesday morning. Since the NAM and to a lesser extent
the GFS have shown to be unreliable on handling the cold air
stratocu deck have relied on the RUC and AVNFPS climatology. An
approaching mid level shortwave will pass just south of the
terminals but can`t rule out scattered flurries from time to time.
But lacking definite timing and they not likely to be an obscuration
to visibilities will not mention in the TAFs. Passage of shortwave
trough axis should see clearing skies in the afternoon with VFR
conditions.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1137 PM CST MON DEC 5 2011
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
/943 PM CST MON DEC 5 2011/
Have raised snow chances a bit overnight, mainly over the far
southern counties and for later in the night. However, did increase
snow chances markedly over the eastern 1/4 of the CWA on Tuesday.
Mid/upper level system ejecting out of NM tonight. Latest RUC is a
bit stronger and further north with the 700mb vorticity center.
Looks like a seeded-feeder setup to start out where a snow from a
higher level of clouds falls into a lower cloud deck and "seed" it
resulting in light snow and/or flurries. However, increasing
dynamics, weak frontogenetic forcing and weak isentropic lift could
generate areas/bands of light snow towards sunrise tomorrow. A
better bet for measurable snow will occur Tuesday morning when the
drier sub-cloud regions have become saturated.
Initial thoughts are a tenth of an inch of snow is possible across
the far southern counties, but possibly enough to make roads slick
as this will be a dry/fluffy snow. Have a bit of concern that a
region of upward vertical motion progged just above a nearly
saturated layer dendritic snow growth region between 12-z15z over
the far eastern counties could yield more than the current half inch
of snow currently forecast. Since confidence in models has been low
of late on how they have handled the cloud structures of late will
go the conservative route and let the mid shift make any changes.
MJ
&&
.PREV DISCUSSION...
/318 PM CST Mon Dec 5 2011/
Brisk northerly winds continues to advect colder air into Missouri
with chilly temperatures the next couple of days. The main concern is
a shortwave in southern New Mexico, south of the Four Corners Low.
Short term high resolution models (NAM and RUC) are indicating that
this wave will progress northeast into west central Missouri on
Tuesday. light to moderate snow has been occurring in the TX
panhandle, aided by upslope, with development toward the northeast.
The models are showing very weak isentropic upglide along with weak
deformation ahead of a weak 700 mb low in eastern Kansas late
tonight and early Tuesday. Moisture is quite limited but have
inserted sct snow showers for much of the area late tonight and
Tuesday. Cannot rule out a narrow band of more persistent snow,
producing very light accumulations. Later shifts will have to
monitor the progress of this system.
Otherwise, the trough axis will pass late Tuesday and Wednesday with
dry conditions.
DB
Medium Range (Thursday through Monday)...
Operational and ensemble members are in good agreement through the
majority of the period depicting primarily stagnant longwave
features over the western hemisphere. Most notable are a seasonably
deep polar vortex centered across northern Hudson Bay and the
Nunavut archipelago and an equally intense ridge through the Gulf of
Alaska (both features in the 1-2 normalized standard deviations away
from average range). This scenario will result in broad
nwly/quasi-zonal flow for locations east of the Rockies with largely
dry conditions and temperature slightly below average into the
weekend. By the end of the period, models also indicate energy
spilling over the top of the western ridge, causing a slight
retrogressive phase, placing much of the central and southern plains
into a warming, swly flow regime. There is naturally uncertainty
into the depth and positioning of swrn conus energy late in the
period, however the effect on weather through the forecast area
would not be felt until after this valid period. Only real potential
sensible weather during this medium range period still appears to be
very light snow/snow flurries Thursday night into Friday morning
across far northern Missouri.
21
&&
.AVIATION...
For the 06Z TAFs, MVFR cigs are likely to persist through the night
and probably Tuesday morning. Since the NAM and to a lesser extent
the GFS have shown to be unreliable on handling the cold air
stratocu deck have relied on the RUC and AVNFPS climatology. An
approaching mid level shortwave will pass just south of the
terminals but can`t rule out scattered flurries from time to time.
But lacking definite timing and they not likely to be an obscuration
to visibilities will not mention in the TAFs. Passage of shortwave
trough axis should see clearing skies in the afternoon with VFR
conditions.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS BUFFALO NY
730 PM EST WED DEC 7 2011
.SYNOPSIS...
LOW PRESSURE TRACKING ALONG A STALLED EAST COAST FRONT WILL BRING
LIGHT SNOW TO PARTS OF WESTERN AND CENTRAL NEW YORK THIS AFTERNOON
AND EVENING. AS THE LOW SLIDES OFF THE NEW ENGLAND COAST
TONIGHT...THE LIGHT SNOW WILL TAPER OFF...THEN GIVE WAY TO LIMITED
LAKE EFFECT SNOW SHOWERS LATER TONIGHT INTO THURSDAY MORNING.
HIGH PRESSURE WILL THEN BRING DRIER AND BREEZY CONDITIONS THURSDAY
AFTERNOON...BEFORE POTENTIALLY SIGNIFICANT LAKE EFFECT SNOW SETS UP
EAST OF THE LAKES THURSDAY NIGHT AND FRIDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
THROUGH 700 PM...PRECIPITATION ASSOCIATED WITH INTENSIFYING LOW
PRESSURE TRACKING ALONG THE ATLANTIC SEABOARD IS LARGELY REMAINING
TO THE EAST. THE BACK EDGE OF THIS HAS NUDGED SLIGHTLY
EASTWARD...LEAVING ONLY FLURRIES IN ALL BUT EASTERN PORTIONS OF
LEWIS COUNTY. THIS TREND WILL CONTINUE...EXITING EAST IN THE NEXT
COUPLE HOURS.
AS COLDER AIR DEEPENS BEHIND THE LOW LATER TONIGHT...SOME LAKE
EFFECT SNOW SHOWERS ARE EXPECTED TO SET UP SOUTHEAST OF BOTH
LAKES. 850 MB TEMPERATURES WILL DROP TO AROUND -10C
OVERNIGHT...RESULTING IN MODERATE INSTABILITY IN A NW TO W FLOG. THE
18Z RUN OF THE NAM AND 21Z RUN OF THE RUC BOTH SHOW A VERY SHALLOW
LAYER OF MOISTURE EAST OF LAKE ERIE. WHILE THERE MAY BE SOME LIGHT
PRECIPITATION...THE LACK OF DENDRITIC SNOW GROWTH WILL LIKELY
RESULT IN A SNOW/DRIZZLE MIX OR FLURRIES WHICH SHOULD STRUGGLE TO
ACCUMULATE.
EAST OF LAKE ONTARIO LOOKS A BIT MORE INTERESTING. THE LONGER
FETCH ACROSS THE LAKE SHOULD ALLOW FOR A BIT MORE MOISTURE TO
BUILD OR MAINTAIN. AS THE INITIAL NW FLOW SHIFTS MORE
WESTERLY...THERE MAY BE A NARROW OPPORTUNITY FOR A LAKE EFFECT
BAND TO DEVELOP BETWEEN MIDNIGHT AND DAYBREAK AS NIGHTTIME
ENHANCES CONVERGENCE ON THE LAKE. BASED ON THIS...DID NUDGE UP
POPS...AND MENTION AN INCH OR TWO OF SNOW POSSIBLE IN OSWEGO
COUNTY. THIS SAID...CONFIDENCE REMAINS FAIRLY LOW GIVEN THE NARROW
OPPORTUNITY FOR DEVELOPMENT.
ON THURSDAY...HIGH PRESSURE WILL RIDGE NORTH FROM THE MIDDLE
ATLANTIC STATES AND CAUSE THE BOUNDARY LAYER WINDS TO BACK TO THE
SOUTHWEST. AT THE SAME TIME...THE MODELS SHOW NOTICEABLY DRIER AIR
ADVECTING EAST ACROSS THE AREA AS THE DAY WEARS ON. AS A
RESULT...LINGERING SNOW SHOWERS OFF LAKE ONTARIO WILL CONTINUE TO
WEAKEN WHILE LIFTING SLOWLY TO THE NORTH. THE SNOW SHOWERS OFF LAKE
ERIE SHOULD END AROUND DAYBREAK THURSDAY.
THE PRESSURE GRADIENT BETWEEN THE DEPARTING LOW AND MIDDLE ATLANTIC
SURFACE RIDGE WILL RESULT IN BREEZY TO WINDY CONDITIONS LATE
THURSDAY MORNING INTO THE AFTERNOON...ESPECIALLY DOWNWIND OF THE
LAKES.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
LAKE EFFECT SNOW WATCHES WILL BE ISSUED FOR DOWNWIND AREAS OF THE
LAKES FOR THIS PERIOD. ALTHOUGH THIS DOES NOT APPEAR TO BE A CLASSIC
SIGNIFICANT LAKE SNOW EVENT...IT WILL BE THE FIRST MODERATE
ACCUMULATING SNOW EVENT OF THE WINTER SEASON FOR THE BUFFALO METRO
AREA AND WATERTOWN.
A POLAR VORTEX OVER HUDSON BAY WILL SEND A SERIES OF SHORTWAVES
SOUTHWARD ALONG WITH SUFFICIENTLY COLD AIR ALOFT. LAKE PROCESSES
WILL TAKE CENTER STAGE DURING THIS PERIOD AS OVER-LAKE INSTABILITY
INCREASES. IT CONTINUES TO LOOK LIKE ACCUMULATING LAKE SNOWS WILL
BEGIN LATER THURSDAY NIGHT WITH THE ARRIVAL PACIFIC BASED MOISTURE
AHEAD OF A STRONG MID LEVEL SHORTWAVE. WINDS BACKING TO
SOUTHWEST WILL LIKELY AIM A CONSOLIDATED SINGLE LAKE SNOW BAND
TOWARDS THE BUFFALO/NIAGARA FALLS AREA OFF LAKE ERIE AS WELL AS
WATERTOWN OFF LAKE ONTARIO...PARTICULARLY AFTER MIDNIGHT.
THERE STILL LOOKS TO BE A FEW UNCERTAINTIES WITH THE OVERALL LAKE
EFFECT SETUP. SOME DISCREPANCIES REMAIN IN LOW LEVEL STEERING FLOW
WITH GFS/CMC SUGGESTING STEERING FLOW JUST A BIT MORE BACKED THAN
THE NAM PLACING HEAVIEST BAND A BIT FARTHER TO THE NORTH...AT LEAST
INITIALLY. MODEL CONSENSUS DOES SUGGEST THAT THE BUF/IAG/ART AREAS
WILL BE THE PRIME TARGET AREAS FROM LATE THURSDAY NIGHT THROUGH
AT LEAST THE FIRST HALF OF FRIDAY. SOME SHEAR SHOWING UP IN THE
MODEL PROFILES MAY KEEP MOST INTENSE BAND FROM SITTING IN ONE AREA
TOO LONGER WHICH MAY LIMIT PROLONGED SNOWFALL RATES. MODEL
SUGGESTION IS THAT THERE WILL BE A SEVERAL HOUR PERIOD LIKELY
CENTERED AROUND 8 AM FRIDAY MORNING WHERE SNOWFALL RATES UP TO AN
INCH WILL BE POSSIBLE...ESPECIALLY IF A DOMINATE BAND DOES INDEED
SET UP.
GRADUALLY VEERING LOW LEVEL FLOW WILL DRIVE THE LAKE SNOWS SLOWLY
SOUTHWARD THROUGH THE DAY EVENTUALLY SETTLING SOUTH OF THE BUFFALO
AND WATERTOWN AREAS...INTO THE SOUTHERN TIER ALONG THE CHAUTAUQUA
RIDGE AND THE TUG HILL BY FRIDAY NIGHT. INCREASING SHEAR ALOFT
AND DRIER AIR WILL WORK IN AT THE SAME TIME AND WE MAY SEE A
SIGNIFICANT DECREASE IN THE LAKE EFFECT ACTIVITY FRIDAY NIGHT...
ESPECIALLY OFF LAKE ERIE.
LAKE EFFECT MAY LINGER EAST OF LAKE ONTARIO THROUGH THE DAY SATURDAY
AS MOISTURE INCREASES AHEAD OF APPROACHING WEAK CLIPPER. ANY LAKE
SNOWS SHOULD COMPLETELY END EARLY SATURDAY AS SUBSIDENCE AND DRIER
AIR CONTINUE TO WORK IN.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
THIS PORTION OF THE FORECAST LOOKS RELATIVELY QUIET. THE REGION
LOOKS TO STAY IN BETWEEN WEAK NORTHERN STREAM CLIPPER SYSTEM
SUNDAY AND BROAD HIGH PRESSURE RIDGED JUST TO THE SOUTH OF THE
REGION. NORTHERN STREAM SYSTEM LOOKS MOISTURE STARVED AT THIS POINT
AND MAY JUST RESULT IN SOME INCREASING CLOUDS FOR NORTHERN TIER
AREAS BUT PRECIPITATION CHANCES LOOK LIMITED. HIGH PRESSURE THEN
BECOME ESTABLISHED OVER THE AREA MONDAY..SLIDING EAST THROUGH MID
WEEK. A COLD FRONT WORKS THROUGH BY MID WEEK..INCREASING SYNOPTIC
SCALE MOISTURE WITH THE SUGGESTION OF ENOUGH COLD AIR BEHIND IT
TO POTENTIALLY THINK ABOUT LAKE INFLUENCES RETURNING.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
LARGELY MVFR CONDITIONS SHOULD IMPROVE TONIGHT AS DRIER AIR BUILDS
IN FROM THE WEST. LINGERING IFR CONDITIONS AT JHW/ART ARE POSSIBLE
THROUGH 03Z. OTHERWISE...MVFR/VFR SHOULD PREDOMINATE...DEPENDING
ON FLOW OFF THE LAKES.
WINDS WILL BE GUSTY THURSDAY...BUT THESE STRONGER WINDS WILL
LIKELY HELP LIMIT CLOUDS TO FORM AS A RESULT OF THE LAKES...THOUGH
PATCHY BKN MVFR CIGS ARE POSSIBLE DURING MUCH OF THE DAY.
OUTLOOK...
THURSDAY NIGHT...MAINLY VFR. LOCAL MVFR/IFR EAST OF THE LAKES IN
LAKE EFFECT SNOW SHOWERS.
FRIDAY...MVFR/IFR WITH SNOW SHOWERS. LOCALLY HEAVIER LAKE EFFECT
SNOW EAST AND NORTHEAST OF THE LAKES.
SATURDAY...MAINLY VFR WITH AREAS OF MVFR IN SNOW SHOWERS SOUTHEAST
OF THE LAKES.
SUNDAY AND MONDAY...VFR.
&&
.MARINE...
A RELATIVE WEAK PRESSURE GRADIENT OVER THE LOWER LAKES WILL
STRENGTHEN LATER THIS EVENING AND TONIGHT AS A DEVELOPING LOW HEADS
NORTHEAST UP THE NEW ENGLAND COAST. A BRISK WEST TO SOUTHWEST FLOW
WILL REMAIN IN PLACE THURSDAY AND FRIDAY...RESULTING IN A HIGH
LIKELIHOOD OF SMALL CRAFT ADVISORY CONDITIONS.
SCA WILL ALSO BE ISSUED FOR THE NIAGARA RIVER AND ST LAWRENCE RIVER
FOR THURSDAY.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WATCH FROM LATE THURSDAY NIGHT THROUGH LATE
FRIDAY NIGHT FOR NYZ006>008.
LAKE EFFECT SNOW WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY
AFTERNOON FOR NYZ001-010>012-085.
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EST FRIDAY
FOR LEZ040-041.
SMALL CRAFT ADVISORY FROM NOON TO 7 PM EST THURSDAY FOR
LEZ020.
SMALL CRAFT ADVISORY FROM 1 PM TO 10 PM EST THURSDAY
FOR LOZ030.
SMALL CRAFT ADVISORY FROM 2 AM THURSDAY TO 1 PM EST FRIDAY
FOR LOZ043-044.
SMALL CRAFT ADVISORY FROM 2 AM THURSDAY TO 9 AM EST FRIDAY
FOR LOZ042.
SMALL CRAFT ADVISORY FROM 2 AM THURSDAY TO 4 PM EST FRIDAY
FOR LOZ045.
SMALL CRAFT ADVISORY FROM 1 PM TO 10 PM EST THURSDAY
FOR SLZ022.
&&
$$
SYNOPSIS...TJP
NEAR TERM...APFFEL/TJP
SHORT TERM...TMA
LONG TERM...TMA
AVIATION...APFFEL
MARINE...TJP
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1043 AM CST TUE DEC 6 2011
.DISCUSSION...
CONCERN FOR THE UPDATE IS THE WIND SPEED. ALL INDICATIONS ARE THE
LOW LEVEL INVERSION WILL HOLD PREVENTING 40KT - 45KT 925MB WIND
FROM MIXING DOWN. HRRR HAS BEEN CONSISTENT IN DEVELOPING SFC GUSTS
TO 40KTS OVER NORTH RRV AND NORTHWEST MINNESOTA COUNTIES 18Z-23Z.
RUC13 AND NAM12 LAPSE RATES REMAIN STRONGLY NEGATIVE...YET
MOMENTUM TRANSFER WILL PROBABLY PUSH TRANSIENT GUSTS TO THE
SURFACE. PLAN TO UP THE WIND GUSTS MORE IN LINE WITH THE HRRR BUT
NOT QUITE AS STRONG.
OTRW THE PREVIOUS FORECAST IS IN GOOD SHAPE. WILL HOLD OFF ON WIND
ADVISORY ALTHOUGH IT COULD BE CLOSE PARTICULARLY IN THE HIGHER
TERRAIN FAVORED AREAS OF THE DEVILS LAKE BASIN AND NORTHWEST
MINNESOTA.
&&
.AVIATION...MAIN CONCERN FOR TODAY WILL BE WIND SPEEDS. BUMPED UP
WINDS PER PUBLIC FCST COORDINATION. EXPECT SOUTHWEST WINDS WITH GUSTS UP TO 35
KNOTS. CIRRUS EXPECTED INTO TONIGHT. PROBABILITY FOR MVFR CIGS
INCREASE BY WEDNESDAY MORNING ALONG COLD FRONT.
&&
.PREV DISCUSSION... /ISSUED 337 AM CST TUE DEC 6 2011/
SHORT TERM...CHALLENGES INCLUDE WINDS TODAY ALONG WITH CLOUD
COVER AND TEMPERATURES THROUGH THE PERIOD. 00Z MODELS IN DECENT
AGREEMENT AND WILL USE A BLEND FOR DETAILS.
TODAY-TONIGHT...STRONG SYSTEM WILL PROPAGATE ACROSS CANADA...WELL
NORTH OF THE REGION. SOUTHWEST WINDS WILL INCREASE INTO THE
AFTERNOON HOURS. MODEL SOUNDINGS SUGGEST MIXING TO 925MB...WITH
30-40KNTS AVAILABLE TO MIX...WITH 20-30 DEGREE DIFFERENCE FROM THE
SFC TO 925MB. CONSIDERING THESE FACTORS SUSTAINED WINDS WILL
LIKELY BE JUST BELOW ADVISORY CRITERIA. STRONGEST WINDS EXPECTED
IN FAVORABLE CROOKSTON TO HALLOCK AREA. SIMILAR SITUATION LAST
FRIDAY PROVED MOST TEMPERATURE GUIDANCE TOO COLD...WITH ECMWF
VERIFYING BEST. FOLLOWING ECMWF...INCREASED MAX TEMPS 3-6F. 850MB
THERMAL RIDGE WILL PROPAGATE THROUGH THE FA 00Z-06Z WED...AND
COLD FROPA THROUGH THE REGION BY 12Z. LIKELY WILL BE SOME SORT OF
NON-DIURNAL TEMPERATURE TREND. INCREASED SKY COVER AS MODEL
GUIDANCE SUGGESTING LOW-LEVEL STRATUS IN COLD AIR ADVECTION JUST
AHEAD OF UPPER WAVE. VERY LIGHT PRECIP ALSO POSSIBLE ACROSS NE FA.
MODEL SOUNDINGS SUGGEST FZDZ POSSIBLE. LOW-LEVEL SATURATED LAYER
AVERAGE TEMP WILL BE AROUND -8C WITH DRY LAYER ABOVE SUGGESTING
SUPERCOOLED WATER DROPLETS. INCLUDED FLURRY/FZDZ AFT 06Z.
WED-THUR NIGHT...UPPER FLOW BECOMES NORTHWEST WITH MULTIPLE
WEAK/FAST MOVING SYSTEMS. COLDER AIRMASS SHOULD CONTINUE TO FILTER
INTO THE REGION WITH COLDEST AIRMASS ON THUR. THERE WILL LIKELY BE
PARTLY CLOUDY PERIODS...BUT BEGINNING TO THINK THAT MUCH OF THIS
PERIOD WILL BE CLOUDY (ESPECIALLY THE NE HALF OF THE FA WHERE
COLDEST 850MB TEMPS WILL BE LOCATED)...AND INCREASED SKY COVER
ACROSS THE NE HALF OF THE FA. DID NOT INSERT PRECIP...BUT WOULD
NOT BE SURPRISED TO SEE PERIODIC FLURRIES. BREEZY WINDS LIKELY.
LONG TERM (FRIDAY-MONDAY)... MODELS IN THE EXTENDED ARE IN GOOD
AGREEMENT AS UPPER LEVEL NW FLOW DOMINATES THE WEATHER PATTERN.
CONTINUED DRY WEATHER WITH TEMPERATURES REBOUNDING TO ABOVE NORMAL
FOR THE WEEKEND WITH HIGHER THICKNESSES BUILDING INTO THE NORTHERN
PLAINS.
AVIATION...MAIN CONCERN FOR TODAY WILL BE WIND SPEEDS. EXPECT
SOUTHWEST WINDS WITH GUSTS UP TO 25 KNOTS. CIRRUS EXPECTED INTO
TONIGHT. PROBABILITY FOR MVFR CIGS INCREASE BY WEDNESDAY MORNING
ALONG COLD FRONT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
EWENS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1247 PM EST TUE DEC 6 2011
.SYNOPSIS...
A SLOW MOVING COLD FRONT WILL GRADUALLY SLIDE EASTWARD TODAY. STRONG
SYSTEM BRINGS RAIN WEDNESDAY...CHANGING TO SNOW WEDNESDAY NIGHT.
HIGH PRESSURE THURSDAY. CLIPPER FRIDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
EARLY MORNING RADAR TRENDS INDICATE TWO POINTS OF FOCUS FOR
PRECIPITATION. COLD FRONT JUST EAST OF OH RIVER VALLEY HAS BEEN THE
IMPETUS FOR SCT SHOWERS OVERNIGHT INTO THE EARLY MORNING. NOT
EXPECTING THIS TO CHANGE MUCH...SAVE FOR THE EVENTUAL EASTWARD CREEP
OF THE FRONTAL BOUNDARY. SECOND FOCUS IS A WAVE RIDING NORTH ALONG
THE FRONT...CURRENTLY LOCATED IN EAST-CENTRAL TN. EXPECTING SHOWERS
ASSOCIATED WITH THIS FEATURE TO BE A LITTLE MORE ORGANIZED AS THEY
ENTER OUR SW VA AND WV MOUNTAIN COUNTIES IN THE COMING HOURS. HRRR HAS HANDLED
ONGOING PRECIPITATION TRENDS THE BEST...STICKING WITH THIS SOLUTION THIS
MORNING.
LOW CIGS AND VSBYS HAVE BEEN REPORTED ALONG THE FRONT AS IT MADE IT
SLOW JOURNEY THROUGH SE OHIO...EXPECTING THIS TREND TO CONTINUE IN
CRW AND CKB VICINITIES BEFORE ANY DAYTIME MIXING CAN IMPROVE
CONDITIONS. LOW STRATUS SHOULD HANG AROUND CWA THROUGH AT LEAST
MIDDAY WITH THE GREATEST IMPACT EVIDENT IN MOUNTAIN COUNTIES.
TEMPS REMAIN COOLER THAN MOS WEST OF TROF AXIS...TWEAKED TEMPS TO
ACCOUNT FOR THIS. GOING WITH A NEAR NON-DIURNAL TREND TO HIGH TEMPS
WITH COLD FRONT STILL IN THE REGION. KEEPING WITH THE TREND OF AOA
MOS TEMPS IN WV MNTS TODAY...WHILE AOB MOS IN THE LOWLANDS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
MUCH BETTER CONSENSUS IN THE MODELS TONIGHT COMPARED TO THE RUNS
LAST NIGHT REGARDING THE VIGOROUS SYSTEM SLATED FOR WEDNESDAY AND
WEDNESDAY NIGHT. MOISTURE WILL HAVE ALREADY OVERSPREAD THE AREA
SOUTH OF THE OHIO RIVER BY 12Z WEDNESDAY...AND EXPECT STEADY RAIN
THROUGH THE FIRST PART OF THAT TIME PERIOD. THE ENTIRE KEY TO THIS
FORECAST IS THE RATE OF THE COLD AIR ADVECTION AND THE SURFACE
TEMPERATURES FALLING BELOW FREEZING. THIS WILL OCCUR FIRST IN THE
HIGHEST ELEVATIONS WHERE THE MOST SIGNIFICANT ACCUMULATIONS ARE
LIKELY. 925MB TEMPERATURE GRADIENT WILL TIGHTEN UP OVER THE EASTERN
MOUNTAINS AND FINALLY KICK THROUGH AFTER AROUND 21Z
WEDNESDAY...WHICH WILL SUBSEQUENTLY ALLOW THE CHANGE OVER TO SNOW
FOR THE REMAINDER OF THE MOUNTAINS. WHILE THE OPERATIONAL MODELS GO
EASY ON THE SPEED OF THE COLD AIR ADVECTION...STRENGTH OF THE
DYNAMICS IN PLAY DO LEAVE SOME QUESTION AS TO WHETHER THIS PARAMETER
IS BEING REPRESENTED WELL BY THESE MODELS...OR IF THERE WILL BE AN
EARLIER TRANSITION TIME TO COME OVER THE NEXT COUPLE OF RUNS.
SYSTEM WILL BE EFFICIENT WHEN IT COMES TO CREATING PRECIPITATION.
JET STREAK OVER 140KTS EXISTS OVER SOUTHEAST OHIO WEDNESDAY...AND
THE 500MB WAVE INDICATES A SHIFT TO A NEGATIVE TILT UPON PASSAGE
THROUGH THE CENTRAL AND SOUTHERN APPALACHIANS. ROBUST FRONTOGENETIC
FORCING WILL COUPLE WITH Q VECTOR CONVERGENCE IN THE UPPER
LEVELS...CREATING ENHANCED OMEGA THROUGH THE DENDRITIC GROWTH
LAYERS...WITH SATURATION OF THE COLUMN EXTENDING FROM THE SURFACE TO
ABOVE 500MB.
THE 03Z RUN OF THE SREF BRINGS PROBABILITIES OF SNOW EXCEEDING 4
INCHES AT ABOUT THE 30 TO 40 PERCENT RANGE FOR POCAHONTAS COUNTY.
CURRENT STATE OF THE FORECAST GRIDS DOES BRING AROUND 4 TO 8 INCHES
TOTAL SNOW ACCUMULATION...RELEGATED TO THE HIGHEST PEAKS OF THE
CWA...ABOVE ROUGHLY 4000FT. WITH THE SLOWER CHANGE OVER TO SNOW IN
THE MOUNTAINS BELOW 4000FT...ABOUT 2 TO 4 INCHES OF SNOW ARE IN THE
FORECAST FOR THIS ISSUANCE. ANOTHER VARIABLE IN THIS OVERALL
EQUATION IS THE MILD AIR THAT HAS BEEN IN PLACE...THE RAIN THAT WILL
PRECEDE THE SNOW...AND THE LENGTH OF TIME NECESSARY FOR THE SNOW TO
ACCUMULATE.
GIVEN THE FACT THAT THIS IS A LATE 3RD PERIOD TO EARLY 4TH PERIOD
EVENT...WILL NOT COMMIT TO THE WATCH FOR NOW. ANY VARIABILITY IN THE
TIMING OF THE BELOW FREEZING AIR COULD ALTER THE SNOWFALL TOTAL
FORECAST SIGNIFICANTLY...IN EITHER DIRECTION. NOT COMFORTABLE WITH
THIS POTENTIAL VOLATILITY TO THE FORECAST AND WILL DRAW ATTENTION TO
THIS SYSTEM IN THE HWO AND RWS TEXT PRODUCTS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
A SHARP AMPLIFYING TROF WILL BE THE MAIN FEATURE EARLY IN THE
EXTENDED. THIS TROF WILL SETTLE INTO EASTERN CONUS...ADVERTISED BY A
CLIPPER FOR FRI NIGHT. BEST LIFT WITH THIS FEATURE WILL SKIRT BY
MAINLY TO NORTH. HOWEVER...GIVEN SOME MOISTURE AND MAGNITUDE OF COLD
AIR BEHIND IT...CANT RULE OUT SOME FLURRIES ABOUT ANYWHERE WITH
FROPA. WILL MENTION FLURRIES IN WX GRIDS FOR LOWLANDS AND CARRY CHC
POPS NORTHERN MTNS. H85 TEMPS COME DOWN TO ARND -10C BY SAT MORNING.
NOT MUCH IN THE WAY OF UPSLOPE AS ATMOSPHERIC COLUMN WILL QUICKLY
DRY OUT AND NW FLOW MEAGER. WILL DRY THINGS OUT QUICKLY SAT...WITH A
RETURN TO SUNSHINE FOR ALL BY AFTN...ALBEIT COLD. DESPITE THE
SUNSHINE...THINK 40F WILL BE HARD TO COME BY IN THE LOWLANDS...WITH
GUIDANCE SUGGESTING MID 30S IS ABOUT IT...WITH 20S IN THE MTNS.
UPR TROF DOESNT STICK ARND IN THIS PROGRESSIVE PATTERN...AS WAA
QUICKLY ALLOWS H85 TEMPS TO RECOVER. HOWEVER...COLD NIGHT WILL BE ON
TAP SAT WITH SFC HIGH BUILDING OVERHEAD. WILL GO WITH AN EARLY LOW
HIGHEST ELEVATIONS AND LEVEL OFF OR SLIGHTLY REBOUND BY SUN
MORNING...WITH LOWLANDS DIPPING DOWN INTO LWR 20S. TOOK TYPICAL COLD
SPOTS INTO TEENS...IE NORTHERN MTN VALLEYS/NE KY.
MODERATING TEMPS WILL CARRY THE WAY EARLY NEXT WEEK...THOUGH STILL
REMAINING ON THE CHILLY SIDE. SHOULD STAY DRY THROUGH TUES.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
A COLD FRONT CURRENTLY LOCATED JUST WEST OF BKW AND EKN IS VERY
SLOWLY MOVING EASTWARD. LIFR/IFR CONDITIONS CAN BE EXPECTED WEST OF
THE FRONT...WITH VFR/MVFR EAST OF THE FRONT. A LOW WILL FORM ALONG
THIS FRONT AND MOVE NORTHWARD LATE TONIGHT AND WEDNESDAY. THIS WILL
BRING MORE RAIN TO THE AREA. WITH THE REGION ON THE WEST SIDE OF THE
FRONT...EXPECT LIFR/IFR CONDITIONS. COLD AIR ON THE BACK SIDE OF
THIS SYSTEM COULD CAUSE A BURST OF SNOW LATE WEDNESDAY.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY...
FORECAST CONFIDENCE: HIGH WEST OF THE FRONT...LOW FOR TIMING OF
FRONT IN THE EAST.
ALTERNATE SCENARIOS: TIMING OF THE FRONT CONTROLS THE COLLAPSE OF
CEILINGS IN THE EASTERN COUNTIES. THIS TIMING COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00
CRW CONSISTENCY M M M M M M M M M L L L
HTS CONSISTENCY H H H H H L L L L M M M
BKW CONSISTENCY M L M M M L L L M L L L
EKN CONSISTENCY L M M M M M M L L L L L
PKB CONSISTENCY M H H M M L L L L M M M
CKB CONSISTENCY M H H H H H H H H L L L
AFTER 18Z WEDNESDAY...
IFR IN PERIODS OF PRECIPITATION AND FOG INTO WEDNESDAY NIGHT.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...26/TAX
NEAR TERM...TAX
SHORT TERM...26
LONG TERM...30
AVIATION...RPY
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
519 AM EST TUE DEC 6 2011
.SYNOPSIS...
LIGHT RAIN SHOWERS EXPECTED TO LINGER THIS MORNING WITH A SLOW MOVING
COLD FRONT IN THE VICINITY. STRONG SYSTEM BRINGS RAIN AND SNOW
WEDNESDAY AND WEDNESDAY NIGHT. HIGH PRESSURE THURSDAY. CLIPPER FRIDAY
NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
EARLY MORNING RADAR TRENDS INDICATE TWO POINTS OF FOCUS FOR
PRECIPITATION. COLD FRONT JUST EAST OF OH RIVER VALLEY HAS BEEN THE
IMPETUS FOR SCT SHOWERS OVERNIGHT INTO THE EARLY MORNING. NOT
EXPECTING THIS TO CHANGE MUCH...SAVE FOR THE EVENTUAL EASTWARD CREEP
OF THE FRONTAL BOUNDARY. SECOND FOCUS IS A WAVE RIDING NORTH ALONG
THE FRONT...CURRENTLY LOCATED IN EAST-CENTRAL TN. EXPECTING SHOWERS
ASSOCIATED WITH THIS FEATURE TO BE A LITTLE MORE ORGANIZED AS THEY
ENTER OUR SW VA AND WV MNT COUNTIES IN THE COMING HOURS. HRRR HAS HANDLED
ONGOING PRECIPITATION TRENDS THE BEST...STICKING WITH THIS SOLN THIS
MORNING.
LOW CIGS AND VSBYS HAVE BEEN REPORTED ALONG THE FRONT AS IT MADE IT
SLOW JOURNEY THROUGH SE OHIO...EXPECTING THIS TREND TO CONTINUE IN
CRW AND CKB VICINITIES BEFORE ANY DAYTIME MIXING CAN IMPROVE
CONDITIONS. LOW STRATUS SHOULD HANG AROUND CWA THROUGH AT LEAST
MIDDAY WITH THE GREATEST IMPACT EVIDENT IN MNT COUNTIES.
TEMPS REMAIN COOLER THAN MOS WEST OF TROF AXIS...TWEAKED TEMPS TO
ACCOUNT FOR THIS. GOING WITH A NEAR NON-DIURNAL TREND TO HIGH TEMPS
WITH COLD FRONT STILL IN THE REGION. KEEPING WITH THE TREND OF AOA
MOS TEMPS IN WV MNTS TODAY...WHILE AOB MOS IN THE LOWLANDS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
MUCH BETTER CONSENSUS IN THE MODELS TONIGHT COMPARED TO THE RUNS
LAST NIGHT REGARDING THE VIGOROUS SYSTEM SLATED FOR WEDNESDAY AND
WEDNESDAY NIGHT. MOISTURE WILL HAVE ALREADY OVERSPREAD THE AREA
SOUTH OF THE OHIO RIVER BY 12Z WEDNESDAY...AND EXPECT STEADY RAIN
THROUGH THE FIRST PART OF THAT TIME PERIOD. THE ENTIRE KEY TO THIS
FORECAST IS THE RATE OF THE COLD AIR ADVECTION AND THE SURFACE
TEMPERATURES FALLING BELOW FREEZING. THIS WILL OCCUR FIRST IN THE
HIGHEST ELEVATIONS WHERE THE MOST SIGNIFICANT ACCUMULATIONS ARE
LIKELY. 925MB TEMPERATURE GRADIENT WILL TIGHTEN UP OVER THE EASTERN
MOUNTAINS AND FINALLY KICK THROUGH AFTER AROUND 21Z
WEDNESDAY...WHICH WILL SUBSEQUENTLY ALLOW THE CHANGE OVER TO SNOW
FOR THE REMAINDER OF THE MOUNTAINS. WHILE THE OPERATIONAL MODELS GO
EASY ON THE SPEED OF THE COLD AIR ADVECTION...STRENGTH OF THE
DYNAMICS IN PLAY DO LEAVE SOME QUESTION AS TO WHETHER THIS PARAMETER
IS BEING REPRESENTED WELL BY THESE MODELS...OR IF THERE WILL BE AN
EARLIER TRANSITION TIME TO COME OVER THE NEXT COUPLE OF RUNS.
SYSTEM WILL BE EFFICIENT WHEN IT COMES TO CREATING PRECIPITATION.
JET STREAK OVER 140KTS EXISTS OVER SOUTHEAST OHIO WEDNESDAY...AND
THE 500MB WAVE INDICATES A SHIFT TO A NEGATIVE TILT UPON PASSAGE
THROUGH THE CENTRAL AND SOUTHERN APPALACHIANS. ROBUST FRONTOGENETIC
FORCING WILL COUPLE WITH Q VECTOR CONVERGENCE IN THE UPPER
LEVELS...CREATING ENHANCED OMEGA THROUGH THE DENDRITIC GROWTH
LAYERS...WITH SATURATION OF THE COLUMN EXTENDING FROM THE SURFACE TO
ABOVE 500MB.
THE 03Z RUN OF THE SREF BRINGS PROBABILITIES OF SNOW EXCEEDING 4
INCHES AT ABOUT THE 30 TO 40 PERCENT RANGE FOR POCAHONTAS COUNTY.
CURRENT STATE OF THE FORECAST GRIDS DOES BRING AROUND 4 TO 8 INCHES
TOTAL SNOW ACCUMULATION...RELEGATED TO THE HIGHEST PEAKS OF THE
CWA...ABOVE ROUGHLY 4000FT. WITH THE SLOWER CHANGE OVER TO SNOW IN
THE MOUNTAINS BELOW 4000FT...ABOUT 2 TO 4 INCHES OF SNOW ARE IN THE
FORECAST FOR THIS ISSUANCE. ANOTHER VARIABLE IN THIS OVERALL
EQUATION IS THE MILD AIR THAT HAS BEEN IN PLACE...THE RAIN THAT WILL
PRECEDE THE SNOW...AND THE LENGTH OF TIME NECESSARY FOR THE SNOW TO
ACCUMULATE.
GIVEN THE FACT THAT THIS IS A LATE 3RD PERIOD TO EARLY 4TH PERIOD
EVENT...WILL NOT COMMIT TO THE WATCH FOR NOW. ANY VARIABILITY IN THE
TIMING OF THE BELOW FREEZING AIR COULD ALTER THE SNOWFALL TOTAL
FORECAST SIGNIFICANTLY...IN EITHER DIRECTION. NOT COMFORTABLE WITH
THIS POTENTIAL VOLATILITY TO THE FORECAST AND WILL DRAW ATTENTION TO
THIS SYSTEM IN THE HWO AND RWS TEXT PRODUCTS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
A SHARP AMPLIFYING TROF WILL BE THE MAIN FEATURE EARLY IN THE
EXTENDED. THIS TROF WILL SETTLE INTO EASTERN CONUS...ADVERTISED BY A
CLIPPER FOR FRI NIGHT. BEST LIFT WITH THIS FEATURE WILL SKIRT BY
MAINLY TO NORTH. HOWEVER...GIVEN SOME MOISTURE AND MAGNITUDE OF COLD
AIR BEHIND IT...CANT RULE OUT SOME FLURRIES ABOUT ANYWHERE WITH
FROPA. WILL MENTION FLURRIES IN WX GRIDS FOR LOWLANDS AND CARRY CHC
POPS NORTHERN MTNS. H85 TEMPS COME DOWN TO ARND -10C BY SAT MORNING.
NOT MUCH IN THE WAY OF UPSLOPE AS ATMOSPHERIC COLUMN WILL QUICKLY
DRY OUT AND NW FLOW MEAGER. WILL DRY THINGS OUT QUICKLY SAT...WITH A
RETURN TO SUNSHINE FOR ALL BY AFTN...ALBEIT COLD. DESPITE THE
SUNSHINE...THINK 40F WILL BE HARD TO COME BY IN THE LOWLANDS...WITH
GUIDANCE SUGGESTING MID 30S IS ABOUT IT...WITH 20S IN THE MTNS.
UPR TROF DOESNT STICK ARND IN THIS PROGRESSIVE PATTERN...AS WAA
QUICKLY ALLOWS H85 TEMPS TO RECOVER. HOWEVER...COLD NIGHT WILL BE ON
TAP SAT WITH SFC HIGH BUILDING OVERHEAD. WILL GO WITH AN EARLY LOW
HIGHEST ELEVATIONS AND LEVEL OFF OR SLIGHTLY REBOUND BY SUN
MORNING...WITH LOWLANDS DIPPING DOWN INTO LWR 20S. TOOK TYPICAL COLD
SPOTS INTO TEENS...IE NORTHERN MTN VALLEYS/NE KY.
MODERATING TEMPS WILL CARRY THE WAY EARLY NEXT WEEK...THOUGH STILL
REMAINING ON THE CHILLY SIDE. SHOULD STAY DRY THROUGH TUES.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
COLD FRONT CURRENTLY JUST EAST OF HTS AND PKB AND SHOULD CONTINUE
TO SLOWLY MOVE EAST THIS MORNING. IFR/LIFR CONDITIONS ALONG THE
FRONT...WITH IMPROVEMENT TO MVFR/IFR BEHIND THE FRONT IN LOW
STRATUS DECK.
CONDITIONS SHOULD IMPROVE TO PREDOMINANTLY MVFR CONDITONS BASED ON
CIGS. EXPECTING ADDITIONAL SHRA TODAY ALONG THE FRONT AND IN MNT
COUNTIES. POSSIBLE IFR CONDITIONS COULD EXIST IN ANY SHOWERS THAT
OCCUR WITH LOWERED VSBYS. RAIN WILL EVENTUALLY TAPER OFF FROM W
TO E TUES AFTERNOON THIS SHOULD ALLOW VSBYS TO IMPROVE WHILE CIGS
WILL BE SLOWER TO RESPOND.
EXPECTING CONDITIONS TO DETERIORATE AGAIN TONIGHT WITH MVFR CIGS
AND VSBYS...PRIMARILY IN THE MOUNTAINS.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: CONDITIONS ALONG THE FRONT HAVE
CAUSED BOUNCING CIGS AND VSBYS TO LESS THAN FORECAST...ANY
VARIANCE IN TIMING COULD CAUSE TIMING CHANGES OF WORSENING
CONDITIONS. DEGREE AND TIMING OF IMPROVEMENT TODAY COULD ALSO VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE 12/06/11
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY M M L L M M M L M M M M
HTS CONSISTENCY L M M M M M L L M H H H
BKW CONSISTENCY M M L M M M M M L L L L
EKN CONSISTENCY H L L L L L L L M M M M
PKB CONSISTENCY M M M M M M L L H M H H
CKB CONSISTENCY L L L L M M M M M M M M
AFTER 12Z WEDNESDAY...
IFR IN PERIODS OF RAIN INTO WEDS...ALSO WITH SNOW EXPECTED IN THE
MOUNTAINS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...26/TAX
NEAR TERM...TAX
SHORT TERM...26
LONG TERM...30
AVIATION...TAX
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
403 AM EST TUE DEC 6 2011
.SYNOPSIS...
LIGHT RAIN SHOWERS EXPECTED TO LINGER THIS MORNING WITH A SLOW MOVING
COLD FRONT IN THE VICINITY. STRONG SYSTEM BRINGS RAIN AND SNOW
WEDNESDAY AND WEDNESDAY NIGHT. HIGH PRESSURE THURSDAY. CLIPPER FRIDAY
NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
330 AM UPDATE...
MAIN CHANGE WITH THIS ISSUANCE IS THE UPDATE TO POPS BASED ON
REGIONAL RADAR TRENDS. HRRR MODEL APPEARS TO BE HANDLING THE
CURRENT SITUATION WELL...WILL BE STICKING WITH THIS SOLN FOR NEXT
WAVE THAT IS TRAVELING ALONG THE FRONT...CURRENTLY IN EAST CENTRAL
TN.
1230 AM UPDATE...
TWEAKED POPS TO BE MORE REPRESENTATIVE OF RADAR ECHOES...HEAVIEST
PRECIPITATION HAS MOVED JUST EAST OF CWA WITH LIGHT SHOWERS
LINGERING BACK ALONG THE COLD FRONT. HEAVIEST RATES SEEM TO BE .10
TO .20 IN/HR...SO NO CONCERN WITH WATER PROBLEMS. LOW STRATUS DECK
APPEARING RIGHT ON TIME BEHIND THE COLD FRONT...EXPECTING STRATUS
TO CONTINUE CREEPING EAST THROUGH THE EARLY MORNING.
PREV DISCN...
MODELS IN FAIRLY GOOD AGREEMENT WITH FRONTAL BOUNDARY PUSHING
THROUGH THE REGION EARLY TUESDAY. LOW TEMPERATURES DEPEND ON
PERFECT TIMING OF THE FRONT. LOOKING AT CURRENT TEMPERATURES
AROUND THE FRONT...WILL GO WITH COOLER MOS IN THE FAR WEST...AND
WARMER MOS IN THE FAR EAST. EXPECTING A LOW STRATUS DECK BEHIND
THE FRONT ON TUESDAY. WITH SUCH A SHALLOW LAYER OF COLD AIR...DO
NOT THINK THE MOS GUIDANCE IS HANDLING IT WELL. THEREFORE...WILL
GO ON THE LOWER SIDE OF MOS GUIDANCE FOR HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
MUCH BETTER CONSENSUS IN THE MODELS TONIGHT COMPARED TO THE RUNS
LAST NIGHT REGARDING THE VIGOROUS SYSTEM SLATED FOR WEDNESDAY AND
WEDNESDAY NIGHT. MOISTURE WILL HAVE ALREADY OVERSPREAD THE AREA
SOUTH OF THE OHIO RIVER BY 12Z WEDNESDAY...AND EXPECT STEADY RAIN
THROUGH THE FIRST PART OF THAT TIME PERIOD. THE ENTIRE KEY TO THIS
FORECAST IS THE RATE OF THE COLD AIR ADVECTION AND THE SURFACE
TEMPERATURES FALLING BELOW FREEZING. THIS WILL OCCUR FIRST IN THE
HIGHEST ELEVATIONS WHERE THE MOST SIGNIFICANT ACCUMULATIONS ARE
LIKELY. 925MB TEMPERATURE GRADIENT WILL TIGHTEN UP OVER THE EASTERN
MOUNTAINS AND FINALLY KICK THROUGH AFTER AROUND 21Z
WEDNESDAY...WHICH WILL SUBSEQUENTLY ALLOW THE CHANGE OVER TO SNOW
FOR THE REMAINDER OF THE MOUNTAINS. WHILE THE OPERATIONAL MODELS GO
EASY ON THE SPEED OF THE COLD AIR ADVECTION...STRENGTH OF THE
DYNAMICS IN PLAY DO LEAVE SOME QUESTION AS TO WHETHER THIS PARAMETER
IS BEING REPRESENTED WELL BY THESE MODELS...OR IF THERE WILL BE AN
EARLIER TRANSITION TIME TO COME OVER THE NEXT COUPLE OF RUNS.
SYSTEM WILL BE EFFICIENT WHEN IT COMES TO CREATING PRECIPITATION.
JET STREAK OVER 140KTS EXISTS OVER SOUTHEAST OHIO WEDNESDAY...AND
THE 500MB WAVE INDICATES A SHIFT TO A NEGATIVE TILT UPON PASSAGE
THROUGH THE CENTRAL AND SOUTHERN APPALACHIANS. ROBUST FRONTOGENETIC
FORCING WILL COUPLE WITH Q VECTOR CONVERGENCE IN THE UPPER
LEVELS...CREATING ENHANCED OMEGA THROUGH THE DENDRITIC GROWTH
LAYERS...WITH SATURATION OF THE COLUMN EXTENDING FROM THE SURFACE TO
ABOVE 500MB.
THE 03Z RUN OF THE SREF BRINGS PROBABILITIES OF SNOW EXCEEDING 4
INCHES AT ABOUT THE 30 TO 40 PERCENT RANGE FOR POCAHONTAS COUNTY.
CURRENT STATE OF THE FORECAST GRIDS DOES BRING AROUND 4 TO 8 INCHES
TOTAL SNOW ACCUMULATION...RELEGATED TO THE HIGHEST PEAKS OF THE
CWA...ABOVE ROUGHLY 4000FT. WITH THE SLOWER CHANGE OVER TO SNOW IN
THE MOUNTAINS BELOW 4000FT...ABOUT 2 TO 4 INCHES OF SNOW ARE IN THE
FORECAST FOR THIS ISSUANCE. ANOTHER VARIABLE IN THIS OVERALL
EQUATION IS THE MILD AIR THAT HAS BEEN IN PLACE...THE RAIN THAT WILL
PRECEDE THE SNOW...AND THE LENGTH OF TIME NECESSARY FOR THE SNOW TO
ACCUMULATE.
GIVEN THE FACT THAT THIS IS A LATE 3RD PERIOD TO EARLY 4TH PERIOD
EVENT...WILL NOT COMMIT TO THE WATCH FOR NOW. ANY VARIABILITY IN THE
TIMING OF THE BELOW FREEZING AIR COULD ALTER THE SNOWFALL TOTAL
FORECAST SIGNIFICANTLY...IN EITHER DIRECTION. NOT COMFORTABLE WITH
THIS POTENTIAL VOLATILITY TO THE FORECAST AND WILL DRAW ATTENTION TO
THIS SYSTEM IN THE HWO AND RWS TEXT PRODUCTS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
A SHARP AMPLIFYING TROF WILL BE THE MAIN FEATURE EARLY IN THE
EXTENDED. THIS TROF WILL SETTLE INTO EASTERN CONUS...ADVERTISED BY A
CLIPPER FOR FRI NIGHT. BEST LIFT WITH THIS FEATURE WILL SKIRT BY
MAINLY TO NORTH. HOWEVER...GIVEN SOME MOISTURE AND MAGNITUDE OF COLD
AIR BEHIND IT...CANT RULE OUT SOME FLURRIES ABOUT ANYWHERE WITH
FROPA. WILL MENTION FLURRIES IN WX GRIDS FOR LOWLANDS AND CARRY CHC
POPS NORTHERN MTNS. H85 TEMPS COME DOWN TO ARND -10C BY SAT MORNING.
NOT MUCH IN THE WAY OF UPSLOPE AS ATMOSPHERIC COLUMN WILL QUICKLY
DRY OUT AND NW FLOW MEAGER. WILL DRY THINGS OUT QUICKLY SAT...WITH A
RETURN TO SUNSHINE FOR ALL BY AFTN...ALBEIT COLD. DESPITE THE
SUNSHINE...THINK 40F WILL BE HARD TO COME BY IN THE LOWLANDS...WITH
GUIDANCE SUGGESTING MID 30S IS ABOUT IT...WITH 20S IN THE MTNS.
UPR TROF DOESNT STICK ARND IN THIS PROGRESSIVE PATTERN...AS WAA
QUICKLY ALLOWS H85 TEMPS TO RECOVER. HOWEVER...COLD NIGHT WILL BE ON
TAP SAT WITH SFC HIGH BUILDING OVERHEAD. WILL GO WITH AN EARLY LOW
HIGHEST ELEVATIONS AND LEVEL OFF OR SLIGHTLY REBOUND BY SUN
MORNING...WITH LOWLANDS DIPPING DOWN INTO LWR 20S. TOOK TYPICAL COLD
SPOTS INTO TEENS...IE NORTHERN MTN VALLEYS/NE KY.
MODERATING TEMPS WILL CARRY THE WAY EARLY NEXT WEEK...THOUGH STILL
REMAINING ON THE CHILLY SIDE. SHOULD STAY DRY THROUGH TUES.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
COLD FRONT CURRENTLY JUST WEST OF HTS AND PKB AND SHOULD CONTINUE TO
SLOWLY MOVE EAST OVERNIGHT. SHRA AHEAD OF FRONT MAY CAUSE
BORDERLINE MVFR CONDITIONS...BUT FOR THE MOST PART VFR STILL
PREDOMINANT EAST OF OHIO RIVER.
ONCE THE FRONT PASSES...CIGS DROP TO MVFR IN LOW STRATUS DECK. BY
DAWN...IFR CIGS AND VSBY WILL BE COMMON IN WIDESPREAD RAIN. THE
RAIN WILL TAPER OFF FROM W TO E TUE...ALLOWING VSBY TO IMPROVE TO
VFR IN THE LOWLANDS AND MVFR IN THE MOUNTAINS BY AFTERNOON.
HOWEVER...CIGS WILL STRUGGLE TO CLIMB TO LOW MVFR ION THE
LOWLANDS. IN THE MOUNTAINS...IT WILL TAKE UNTIL ABOUT DAWN FOR
CIGS TO GET DOWN TO IFR BUT THEN CIGS WILL REMAIN IFR OR CLOSE TO
IT THROUGH THE DAY TUE.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING OF THE FRONT COULD VARY...CAUSING TIMING
OF IFR/LIFR CONDITIONS TO VARY. DENSITY OF THE FOG TONIGHT COULD
ALSO VARY. TIMING AND DEGREE OF IMPROVEMENT TUE ALSO COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE 12/06/11
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY M M L L M M M L M M M M
HTS CONSISTENCY L M M M M M L L M H H H
BKW CONSISTENCY M M L M M M M M L L L L
EKN CONSISTENCY H L L L L L L L M M M M
PKB CONSISTENCY M M M M M M L L H M H H
CKB CONSISTENCY L L L L M M M M M M M M
AFTER 06Z WEDNESDAY...
IFR IN PERIODS OF RAIN INTO TUE NT...AND IN THE MOUNTAINS IN SNOW
WED NT.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...26/TAX
NEAR TERM...RPY/TAX
SHORT TERM...26
LONG TERM...30
AVIATION...TAX
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
344 AM EST TUE DEC 6 2011
.SYNOPSIS...
LIGHT RAIN SHOWERS EXPECTED TO LINGER THIS MORNING WITH A SLOW MOVING
COLD FRONT IN THE VICINITY. COLDER WEDNESDAY WITH TROUGH AXIS
ALOFT CROSSING WEDNESDAY NIGHT. HIGH PRESSURE THURSDAY. CLIPPER
FRIDAY NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
330 AM UPDATE...
MAIN CHANGE WITH THIS ISSUANCE IS THE UPDATE TO POPS BASED ON
REGIONAL RADAR TRENDS. HRRR MODEL APPEARS TO BE HANDLING THE
CURRENT SITUATION WELL...WILL BE STICKING WITH THIS SOLN FOR NEXT
WAVE THAT IS TRAVELING ALONG THE FRONT...CURRENTLY IN EAST CENTRAL
TN.
1230 AM UPDATE...
TWEAKED POPS TO BE MORE REPRESENTATIVE OF RADAR ECHOES...HEAVIEST
PRECIPITATION HAS MOVED JUST EAST OF CWA WITH LIGHT SHOWERS
LINGERING BACK ALONG THE COLD FRONT. HEAVIEST RATES SEEM TO BE .10
TO .20 IN/HR...SO NO CONCERN WITH WATER PROBLEMS. LOW STRATUS DECK
APPEARING RIGHT ON TIME BEHIND THE COLD FRONT...EXPECTING STRATUS
TO CONTINUE CREEPING EAST THROUGH THE EARLY MORNING.
PREV DISCN...
MODELS IN FAIRLY GOOD AGREEMENT WITH FRONTAL BOUNDARY PUSHING
THROUGH THE REGION EARLY TUESDAY. LOW TEMPERATURES DEPEND ON
PERFECT TIMING OF THE FRONT. LOOKING AT CURRENT TEMPERATURES
AROUND THE FRONT...WILL GO WITH COOLER MOS IN THE FAR WEST...AND
WARMER MOS IN THE FAR EAST. EXPECTING A LOW STRATUS DECK BEHIND
THE FRONT ON TUESDAY. WITH SUCH A SHALLOW LAYER OF COLD AIR...DO
NOT THINK THE MOS GUIDANCE IS HANDLING IT WELL. THEREFORE...WILL
GO ON THE LOWER SIDE OF MOS GUIDANCE FOR HIGHS.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY/...
RECENT MODEL RUNS HAVE COME INTO BETTER AGREEMENT IN THE SHORT TERM
PERIOD. PROGRESSION OF SURFACE FRONT ACROSS THE CWA HAS BEEN
TRENDING SLOWER. NAM EVEN APPEARS TO HANG UP THE FRONT OVER THE
MOUNTAINS WEDNESDAY...WITH SEVERAL WAVES RIDING ALONG THE
FRONT...WHILE GFS FOR EXAMPLE...APPEARS TO CLEAR THE SURFACE FRONT
EAST OF THE MOUNTAINS LATE TUESDAY NIGHT OR WEDNESDAY. MUCH OF THE
INITIAL PRECIPITATION IN THE SHORT TERM WILL START OUT AS RAIN...BUT
BY WEDNESDAY NIGHT/THURSDAY...A MORE SIGNIFICANT SHORTWAVE TROUGH
WILL APPROACH FROM THE WEST. STILL SOME DIFFERENCES IN THE EXACT
TRACK...TIMING...AND THUS NORTHWARD EXTEND OF THE PRECIPITATION
SHIELD ASSOCIATED WITH THIS...SO FOR NOW...KIND OF WENT WITH A SPLIT
BETWEEN THE 12Z NAM AND 12Z GFS. THINKING ENOUGH COLD AIR WILL BE IN
PLACE LATE WEDNESDAY NIGHT/EARLY THURSDAY FOR PRECIPITATION TO
GRADUALLY CHANGE OVER TO SNOW CWA WIDE. WITH 1000-500MB THICKNESSES
HOVERING AROUND 540 AND RATHER MOIST SOUNDINGS WITH MUCH OF THE
SOUNDING NEAR 0C...EXPECTING A HEAVIER...WET SNOW. ACCUMULATIONS ARE
STILL UP IN THE AIR A BIT...BUT REALLY ONLY EXPECTING ACCUMULATIONS
IN THE HIGHER TERRAIN...PARTICULARLY NORTHERN MOUNTAIN ZONES. ANY
SNOW IN THE LOWLANDS WILL LIKELY NOT ACCUMULATE DUE TO WARM GROUND.
FOR NOW...DECIDED TO BE CONSERVATIVE ON SNOWFALL ACCUMULATIONS...AND
HAVE GENERALLY 2-4 INCHES IN THE NORTHERN MOUNTAIN ZONES...WITH
GENERALLY 1-3 INCHES IN SURROUNDING HIGHER TERRAIN COUNTIES.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A SHARP AMPLIFYING TROF WILL BE THE MAIN FEATURE EARLY IN THE
EXTENDED. THIS TROF WILL SETTLE INTO EASTERN CONUS...ADVERTISED BY A
CLIPPER FOR FRI NIGHT. BEST LIFT WITH THIS FEATURE WILL SKIRT BY
MAINLY TO NORTH. HOWEVER...GIVEN SOME MOISTURE AND MAGNITUDE OF COLD
AIR BEHIND IT...CANT RULE OUT SOME FLURRIES ABOUT ANYWHERE WITH
FROPA. WILL MENTION FLURRIES IN WX GRIDS FOR LOWLANDS AND CARRY CHC
POPS NORTHERN MTNS. H85 TEMPS COME DOWN TO ARND -10C BY SAT MORNING.
NOT MUCH IN THE WAY OF UPSLOPE AS ATMOSPHERIC COLUMN WILL QUICKLY
DRY OUT AND NW FLOW MEAGER. WILL DRY THINGS OUT QUICKLY SAT...WITH A
RETURN TO SUNSHINE FOR ALL BY AFTN...ALBEIT COLD. DESPITE THE
SUNSHINE...THINK 40F WILL BE HARD TO COME BY IN THE LOWLANDS...WITH
GUIDANCE SUGGESTING MID 30S IS ABOUT IT...WITH 20S IN THE MTNS.
UPR TROF DOESNT STICK ARND IN THIS PROGRESSIVE PATTERN...AS WAA
QUICKLY ALLOWS H85 TEMPS TO RECOVER. HOWEVER...COLD NIGHT WILL BE ON
TAP SAT WITH SFC HIGH BUILDING OVERHEAD. WILL GO WITH AN EARLY LOW
HIGHEST ELEVATIONS AND LEVEL OFF OR SLIGHTLY REBOUND BY SUN
MORNING...WITH LOWLANDS DIPPING DOWN INTO LWR 20S. TOOK TYPICAL COLD
SPOTS INTO TEENS...IE NORTHERN MTN VALLEYS/NE KY.
MODERATING TEMPS WILL CARRY THE WAY EARLY NEXT WEEK...THOUGH STILL
REMAINING ON THE CHILLY SIDE. SHOULD STAY DRY THROUGH TUES.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
COLD FRONT CURRENTLY JUST WEST OF HTS AND PKB AND SHOULD CONTINUE TO
SLOWLY MOVE EAST OVERNIGHT. SHRA AHEAD OF FRONT MAY CAUSE
BORDERLINE MVFR CONDITIONS...BUT FOR THE MOST PART VFR STILL
PREDOMINANT EAST OF OHIO RIVER.
ONCE THE FRONT PASSES...CIGS DROP TO MVFR IN LOW STRATUS DECK. BY
DAWN...IFR CIGS AND VSBY WILL BE COMMON IN WIDESPREAD RAIN. THE
RAIN WILL TAPER OFF FROM W TO E TUE...ALLOWING VSBY TO IMPROVE TO
VFR IN THE LOWLANDS AND MVFR IN THE MOUNTAINS BY AFTERNOON.
HOWEVER...CIGS WILL STRUGGLE TO CLIMB TO LOW MVFR ION THE
LOWLANDS. IN THE MOUNTAINS...IT WILL TAKE UNTIL ABOUT DAWN FOR
CIGS TO GET DOWN TO IFR BUT THEN CIGS WILL REMAIN IFR OR CLOSE TO
IT THROUGH THE DAY TUE.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING OF THE FRONT COULD VARY...CAUSING TIMING
OF IFR/LIFR CONDITIONS TO VARY. DENSITY OF THE FOG TONIGHT COULD
ALSO VARY. TIMING AND DEGREE OF IMPROVEMENT TUE ALSO COULD VARY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE 12/06/11
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY M M L L M M M L M M M M
HTS CONSISTENCY L M M M M M L L M H H H
BKW CONSISTENCY M M L M M M M M L L L L
EKN CONSISTENCY H L L L L L L L M M M M
PKB CONSISTENCY M M M M M M L L H M H H
CKB CONSISTENCY L L L L M M M M M M M M
AFTER 06Z WEDNESDAY...
IFR IN PERIODS OF RAIN INTO TUE NT...AND IN THE MOUNTAINS IN SNOW
WED NT.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...SL/30/TAX
NEAR TERM...RPY/TAX
SHORT TERM...SL
LONG TERM...30
AVIATION...TAX
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
509 AM EST TUE DEC 6 2011
.SYNOPSIS...
A MOIST SOUTHWEST FLOW ALOFT WILL INTERACT WITH A SLOW MOVING
WAVY FRONTAL BOUNDARY TO BRING UNSETTLED CONDITIONS TO THE AREA
THROUGH MID WEEK. UPPER LEVEL ENERGY MIGRATING FROM THE ROCKIES
EASTWARD ACROSS THE CENTRAL PLAINS STATES INTO THE APPALACHIANS
SHOULD INDUCE A MORE DEFINED AREA OF LOW PRESSURE OVER THE
CAROLINAS BY WEDNESDAY NIGHT. THIS SYSTEM MAY SPREAD A SWATH OF
LIGHT TO MODERATE SNOW ACROSS SOUTHERN AND EASTERN PENNSYLVANIA AS
IT TRACKS NORTHEAST NEAR THE MID-ATLANTIC COAST. SEASONABLY COLD
AND BRISK BUT MAINLY DRY WEATHER IS ANTICIPATED FROM LATER THIS
WEEK INTO THE FIRST PART OF THE WEEKEND...WITH SOME MODERATION IN
TEMPERATURES LIKELY HEADING INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 0530Z THE SFC COLD FRONT WAS LOCATED JUST E OF A JHW-YNG-ZZV
LINE. RDR SHOWS GREATEST CVRG OR LGT/MOD RNFL MOVG ACRS THE NW
AND NCNTRL MTNS. MDL AND CIWS DATA SUGGEST PCPN WILL BECOME
DISORGANIZED THROUGH THE PREDAWN HOURS AS BEST MID/UPPER FORCING
SLIDES OFF TO THE NORTH AND FNTL WAVE LIFTS NEWD FM SW PA. WV/IR
SATL DATA ALSO SHOWS DRY SLOT SURGING NEWD INTO THE UPPER OH VLY
WHICH SHOULD ALSO HELP TO CUT OFF PCPN TO SOME EXTENT. AN
UNSEASONABLY MILD EARLY DEC NIGHT WILL CONTINUE OVR MUCH OF THE
CWA WITH READINGS IN THE MID 40S TO MID 50S. THE EXCEPTION WILL BE
OVR THE FAR NW AS COLDER AIR WRAPS IN FM THE NORTH. MARGINAL BL
AND LLVL WET BULBS SUGGEST A LOW CHANCE FOR RA/SN MIX WITH SFC
TEMPS BOTTOMING OUT IN THE MID TO UPPER 30S.
PREVIOUS DISC FROM 1059 PM...
SFC COLD FRONT HAS STALLED OUT TEMPORARILY THIS EVENING...JUST TO
THE SE OF INTERSTATE 90 IN FAR NWRN PENN. 03Z SFC OBS...AND THE 02Z
RUC DISPLAY A VERY TIGHT...MEAN SFC-925 MB TEMP GRADIENT FROM
KERI...SW TO KCMH. RUC INDICATES THAT THIS BOUNDARY WILL CRAWL
EAST TO NEAR A KELZ...TO KDUJ AND KPIT LINE BY THE 10-12Z TUESDAY
TIMEFRAME.
THE RAIN AREA /THAT HAS BEEN STREAMING NE AND CONFINED NEAR...AND
JUST IN THE WAKE OF THE FRONT/ HAS STARTED TO QUICKLY EXPAND
EAST AHEAD OF THIS BOUNDARY /NEARING KUNV ATTM AND LIKELY
BEGINNING IN KIPT BY 05Z/...AS THE NOSE OF A STRENGTHENING
50-55KT/850 MB SWRLY JET MOVES NORTH ACROSS THE ALLEGHENY PLATEAU.
THIS LLJ ENERGY WILL BE AIDED BY INCREASING 850-700 UVVEL BENEATH
PULSES OF UPPER LEVEL DIVERGENCE BENEATH THE RIGHT ENTRANCE REGION
OF A 110 KT JET LIFTING INTO NEW YORK STATE TOWARD DAYBREAK.
RUC AND SREF MEAN...12-HOUR QPF IS AROUND 0.50 OF AN INCH ACROSS
OUR FAR NW ZONES /NEAR KBFD/...AND BETWEEN 0.10 AND 0.25 OF AN
INCH THROUGHOUT THE CENTRAL COUNTIES. RAINFL AMOUNTS OVER MUCH OF
THE LOWER SUSQUEHANNA VALLEY REGION WILL STAY AOB 0.10 IF AN INCH
THROUGH 12Z TUESDAY.
LATEST NAM/HRRR SPREADS THE PRECIP GRADUALLY TO THE EAST ACROSS
THE REST OF THE SCENT MTNS AND SUSQ VALLEY THROUGH THE PREDAWN
HOURS. TIMING OF HIGHEST CHCS FOR PRECIP IS BETWEEN 05-10Z TUES
ACROSS THE NW HALF OF THE CWA...AND DURING THE MID TO LATE MORNING
IN THE SE ZONES.
RUC 925 MB WET BULB TEMPS SINK TO A MIN OF ABOUT PLUS 1-2C ACROSS
THE FAR NW BY 12Z TUESDAY...SO A CHANG-OVER TO SLEET/WET SNOW IS
NOT EXPECTED AS FAR EAST AS WARREN OR KBFD.
POPS WILL DECREASE AROUND OR SHORTLY AFTER DAYBREAK TUESDAY IN THE
FAR NW. THE EXTENSIVE CLOUD COVER AND CONTINUED LIGHT SOUTH TO
SOUTHEAST SFC WINDS ACROSS MOST OF THE AREA SHOULD KEEP TEMPS FROM
FALLING VERY MUCH TONIGHT. TEMPS WILL FALL AN ADDITIONAL SEVERAL
DEG F ACROSS THE HIGHER TERRAIN OF THE NORTH AND WEST...BUT WILL
BE STEADY OR FALL JUST A FEW DEGREES ELSEWHERE AS MOISTURE BUILDS
AND CLOUDS LOWER SUBSTANTIALLY. WILL JUST MENTION PATCHY 2-3SM FOG
IN THE WHOLE AREA FOR THE TIME BEING.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
A FAIRLY PROGRESSIVE AND DYNAMIC H5/H7 SHORTWAVE TROUGH WILL
STREAK EWD FM THE LWR MS VLY ACRS THE SRN APPALACHIANS TO THE MID-
ATLC SEABOARD WED/WED NGT INTO EARLY THURS. AS THE MID/UPPER LEVEL
TROUGH TAKES ON A NEGATIVE TILT...STRONG HEIGHT FALLS AND UPPER
LEVEL DIVERGENCE WILL INDUCE SFC LOW DEVELOPMENT INVOF THE
CAROLINAS/VA VCNTY WED NGT. THE DEEP LAYER ASCENT AND FAVORABLE
JET DYNAMICS WILL LEAD TO LOWERING SNOW LEVELS AS COLD AIR WRAPS
INTO THE SYS AS IT ROTATES UP ACRS ERN NY INTO NEW ENGLAND. GUID
INDICATES DECENT CLUSTERING WITH THE SFC LOW BUT LINGERING TIMING
AND TRACK UNCERTAINTY STILL REMAINS...ALTHOUGH THE SPREADS HAVE
NARROWED CONSIDERABLY FROM 24 HOURS AGO. THE PREFERENCE IS STILL
TWD A FASTER PROGRESSION OF THE SYS OVERALL AND THE SREF AND GEFS
MEANS APPEAR TO BE ADJUSTING IN THIS DIRECTION. WHILE THERE IS A
MODEST INCREASE IN FORECASTER CONFIDENCE IN LIGHT OF THE NARROWING
SPREADS AND GENERAL TREND TWD A CONSENSUS SOLN...THE RECENT POOR
CONTINUITY AND LINGERING UNCERTAINTY /ESPECIALLY IN THE TRACK OF
THE LOW/ LEADS TO BELOW AVG CONFIDENCE.
IT APPEARS THAT A 12-HR PD OF MOD TO PERHAPS HVY PCPN WILL BE
POSSIBLE OVR THE SRN AND ERN ZONES IN THE DEFORMATION ZONE AND
COMMA HEAD LOCATED ON THE NW EDGE OF THE EVENTUAL SFC LOW TRACK.
PCPN SHOULD CHANGEOVER FROM RAIN TO SNOW AS COLD AIR FILLS IN ON
THE BACKSIDE OF THE DEEPENING SYS. THE GFS SFC LOW TRACK IS
FURTHER EAST/OFFSHORE COMPARED TO THE NAM/ECMWF/CAN/GEFS...THUS
BRINGING THE THREAT OF LESS SNOW COMPARED TO THE OTHER GUID...WHICH
IS INDICATING A SOLID 0.50 TO 1 INCH OF LIQUID IN 12 HRS OVR MUCH
OF SERN PA ENDING 12Z THURS. THE LOWER ELEVATIONS/VALLEYS WILL
LKLY START AS RAIN AND TRANSITION OVR TO SNOW WHICH COULD LIMIT
ACCUMS. MEANWHILE HIGHER ELEVATIONS SHOULD SEE HIGH PROBABILITIES
FOR MORE SIGNIFICANT ACCUMS GIVEN LONGER DURATION. OVERALL...
CONFIDENCE DID NOT QUITE MEET THE WATCH ISSUANCE THRESHOLD ALTHOUGH
CONSIDERED ISSUING WSW WITH COLLABORATION FROM LWX AND PHI. FOR
NOW WILL KEEP MENTION IN THE HWO MENTIONING LIGHT TO MODERATE
ACCUMS POSSIBLE. IT SHOULD BE NOTED THAT MOD TO HVY ACCUMS IN
EXCESS OF 6 INCHES ARE ALSO POSSIBLE GIVEN MDL QPFS...WITH A LOWER
RISK/PROBABILITY OUTCOME DUE TO THE AFOREMENTIONED UNCERTAINTY IN
THE TRACK/TIMING AND THERMAL PROFILES/ELEVATION DEPENDENCE.
THE LOW WILL MOVE OFF THE SOUTHERN NEW ENGLAND COAST BY DAYBREAK
THURS WITH A BRISK AND COLD WLY FLOW REGIME PREVAILING OVR CNTRL
PA DURING THE DAY. THIS SHOULD TRANSLATE INTO A BRIEF PD OF MTN
SNOW SHOWERS EARLY GIVEN FAVORABLE DOWNWIND LAKE TRAJECTORIES AND
COLD CYC FLOW ALOFT. THE LLVL FLOW WILL BACK MORE TO THE WSW THURS
NGT INTO FRI AS A NRN STREAM TROUGH ROTATES INTO THE UPPER MIDWEST
AROUND THE BASE OF HUDSON BAY VORTEX.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
A MSTR-STARVED COLD FNT MARKING THE LEADING EDGE OF THE UPPER
MIDWEST H5 TROUGH AND ACCOMPANYING SEASONABLY COLD /-12 TO -14C AT
850MB/ AIR ALOFT WILL CROSS THE AREA FRI NGT...WITH LITTLE
FANFARE OTHER THAN SOME LAKE ENHANCED/UPSLOPE SNOW SHOWERS ALONG
THE ALLEGHENIES. TEMPERATURES SHOULD BOTTOM ON SATURDAY AS THE CORE
UPPER TROUGH AXIS MOVES OVERHEAD. HIGH PRES WILL OVERSPREAD THE
REGION ON SUN AND DOMINATE THE PATTERN INTO EARLY NEXT WEEK.
RETURN FLOW AROUND THE HIGH SHOULD LEAD TO MODERATING TEMPS WITH
FAIR WEATHER PERSISTING THROUGH MONDAY.
&&
.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
A COLD FRONT...LOCATED EXTENDING ACROSS THE WESTERN HALF OF PA AT
07Z...WILL PUSH SLOWLY SOUTHEAST ACROSS PENNSYLVANIA LATE
TONIGHT...ACCOMPANIED BY OCNL LGT RAIN. CURRENT ANALYSIS SHOWS IFR
CONDS CONFINED TO NW PA...BEHIND FRONT. HOWEVER...AS THE FRONT
PUSHES EAST...EXPECT DETERIORATING FLYING CONDS TO SPREAD OVER THE
REST OF PA. SHORT RANGE MDL DATA SUPPORTS IFR CONDS BECOMING
WIDESPREAD ACROSS THE REST OF CENTRAL PA AFTER 09Z.
MODEST IMPROVEMENT IS EXPECTED BY TUESDAY AFTN...AS FRONT BEGINS TO
PUSH EAST OF THE REGION. MANY LOCATIONS WILL LIKELY IMPROVE TO
MVFR CONDS. HOWEVER...RESIDUAL MOISTURE ASCENDING THE W MTNS COULD
LEAD TO LINGERING IFR CIGS AT JST AND BFD THRU TUE NIGHT.
OUTLOOK...
WED...AM LOW CIGS POSSIBLE W MTNS.
WED NIGHT...RAIN/SNOW AND LOW CIGS POSSIBLE SOUTHEAST.
THU...NO SIG WX EXPECTED.
FRI...PM SHSN POSSIBLE NW MTNS.
SAT...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...LAMBERT/STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...FITZGERALD/CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
229 AM EST TUE DEC 6 2011
.SYNOPSIS...
A MOIST SOUTHWEST FLOW ALOFT WILL INTERACT WITH A SLOW MOVING
WAVY FRONTAL BOUNDARY TO BRING UNSETTLED CONDITIONS TO THE AREA
THROUGH MID WEEK. UPPER LEVEL ENERGY MIGRATING FROM THE ROCKIES
EASTWARD ACROSS THE CENTRAL PLAINS STATES INTO THE APPALACHIANS
SHOULD INDUCE A MORE DEFINED AREA OF LOW PRESSURE OVER THE
SOUTHERN MID-ATLANTIC REGION BY WEDNESDAY NIGHT BEFORE LIFTING
NORTHEAST OFF THE SOUTHERN NEW ENGLAND COAST EARLY THURSDAY
MORNING. COLD AND BRISK WEATHER IS ANTICIPATED FROM LATER THIS
WEEK INTO THE FIRST PART OF THE WEEKEND...WITH SOME MODERATION
IN TEMPERATURES LIKELY HEADING INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
AT 0530Z THE SFC COLD FRONT WAS LOCATED JUST E OF A JHW-YNG-ZZV
LINE. RDR SHOWS GREATEST CVRG OR LGT/MOD RNFL MOVG ACRS THE NW
AND NCNTRL MTNS. MDL AND CIWS DATA SUGGEST PCPN WILL BECOME
DISORGANIZED THROUGH THE PREDAWN HOURS AS BEST MID/UPPER FORCING
SLIDES OFF TO THE NORTH AND FNTL WAVE LIFTS NEWD FM SW PA. WV/IR
SATL DATA ALSO SHOWS DRY SLOT SURGING NEWD INTO THE UPPER OH VLY
WHICH SHOULD ALSO HELP TO CUT OFF PCPN TO SOME EXTENT. AN
UNSEASONABLY MILD EARLY DEC NIGHT WILL CONTINUE OVR MUCH OF THE
CWA WITH READINGS IN THE MID 40S TO MID 50S. THE EXCEPTION WILL BE
OVR THE FAR NW AS COLDER AIR WRAPS IN FM THE NORTH. MARGINAL BL
AND LLVL WET BULBS SUGGEST A LOW CHANCE FOR RA/SN MIX WITH SFC
TEMPS BOTTOMING OUT IN THE MID TO UPPER 30S.
PREVIOUS DISC FROM 1059 PM...
SFC COLD FRONT HAS STALLED OUT TEMPORARILY THIS EVENING...JUST TO
THE SE OF INTERSTATE 90 IN FAR NWRN PENN. 03Z SFC OBS...AND THE 02Z
RUC DISPLAY A VERY TIGHT...MEAN SFC-925 MB TEMP GRADIENT FROM
KERI...SW TO KCMH. RUC INDICATES THAT THIS BOUNDARY WILL CRAWL
EAST TO NEAR A KELZ...TO KDUJ AND KPIT LINE BY THE 10-12Z TUESDAY
TIMEFRAME.
THE RAIN AREA /THAT HAS BEEN STREAMING NE AND CONFINED NEAR...AND
JUST IN THE WAKE OF THE FRONT/ HAS STARTED TO QUICKLY EXPAND
EAST AHEAD OF THIS BOUNDARY /NEARING KUNV ATTM AND LIKELY
BEGINNING IN KIPT BY 05Z/...AS THE NOSE OF A STRENGTHENING
50-55KT/850 MB SWRLY JET MOVES NORTH ACROSS THE ALLEGHENY PLATEAU.
THIS LLJ ENERGY WILL BE AIDED BY INCREASING 850-700 UVVEL BENEATH
PULSES OF UPPER LEVEL DIVERGENCE BENEATH THE RIGHT ENTRANCE REGION
OF A 110 KT JET LIFTING INTO NEW YORK STATE TOWARD DAYBREAK.
RUC AND SREF MEAN...12-HOUR QPF IS AROUND 0.50 OF AN INCH ACROSS
OUR FAR NW ZONES /NEAR KBFD/...AND BETWEEN 0.10 AND 0.25 OF AN
INCH THROUGHOUT THE CENTRAL COUNTIES. RAINFL AMOUNTS OVER MUCH OF
THE LOWER SUSQUEHANNA VALLEY REGION WILL STAY AOB 0.10 IF AN INCH
THROUGH 12Z TUESDAY.
LATEST NAM/HRRR SPREADS THE PRECIP GRADUALLY TO THE EAST ACROSS
THE REST OF THE SCENT MTNS AND SUSQ VALLEY THROUGH THE PREDAWN
HOURS. TIMING OF HIGHEST CHCS FOR PRECIP IS BETWEEN 05-10Z TUES
ACROSS THE NW HALF OF THE CWA...AND DURING THE MID TO LATE MORNING
IN THE SE ZONES.
RUC 925 MB WET BULB TEMPS SINK TO A MIN OF ABOUT PLUS 1-2C ACROSS
THE FAR NW BY 12Z TUESDAY...SO A CHANG-OVER TO SLEET/WET SNOW IS
NOT EXPECTED AS FAR EAST AS WARREN OR KBFD.
POPS WILL DECREASE AROUND OR SHORTLY AFTER DAYBREAK TUESDAY IN THE
FAR NW. THE EXTENSIVE CLOUD COVER AND CONTINUED LIGHT SOUTH TO
SOUTHEAST SFC WINDS ACROSS MOST OF THE AREA SHOULD KEEP TEMPS FROM
FALLING VERY MUCH TONIGHT. TEMPS WILL FALL AN ADDITIONAL SEVERAL
DEG F ACROSS THE HIGHER TERRAIN OF THE NORTH AND WEST...BUT WILL
BE STEADY OR FALL JUST A FEW DEGREES ELSEWHERE AS MOISTURE BUILDS
AND CLOUDS LOWER SUBSTANTIALLY. WILL JUST MENTION PATCHY 2-3SM FOG
IN THE WHOLE AREA FOR THE TIME BEING.
&&
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
FRONT INCHES IT/S WAY ACROSS THE REST OF CENTRAL/ERN PENN
ON TUES. NO SIGNIFICANT WAVES DEVELOP ALONG IT...SO GENERALLY SCT
SHRA WILL FALL THROUGH THE DAY ON TUESDAY. LIKELIHOOD OF SHOWERS
FAIRLY HIGH DURING THE WHOLE DAY...AND PINNING A TIME FOR HIGHEST
POPS NOT EASY. WILL PAINT THE HIGHER POPS IN THE AFTN AS PRESSURE
LOWER ON THE FRONT SLIGHTLY. THE MORE-ORGANIZED SHOWERS AND HIGHER
POPS SHOULD BE IN THE SERN HALF OF THE FORECAST AREA. UPPER TROUGH
STAYS HIGHLY POSITIVE AND DRAGS ALONG. THUS...LITTLE CHANGE IN THE
SFC PATTERN AND FORCING IS SEEN FOR EARLY TUES NIGHT.
HOWEVER...THE SFC BOUNDARY DOES SEEM TO CLEAR THE FORECAST AREA
TUES NIGHT...AND WILL LOWER POPS OVER MUCH OF THE AREA IN THE
SECOND HALF OF THE NIGHT. UPSLOPE IN THE WEST COULD FORCE ENOUGH
MOISTURE UP INTO THE HILLS TO GENERATE SHOWERS...BUT P-TYPE IS
QUESTIONABLE. 8H TEMPS ARE ABOVE FZG THROUGH 06-09Z IN THE WRN
HIGHLANDS...BUT SFC TEMPS SHOULD FOLLOW ALONG IN LOCK STEP AND GET
INTO THE 20S NW AND NEAR FZG IN THE LAURELS. WILL THEREFORE
MENTION SHSN MIXING IN TO THE SCT SHRA IN THE W AFTER MIDNIGHT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
A POSITIVE TILTED LONG WAVE TROUGH EXTENDING FROM THE GREAT LAKES
INTO TX ON WED WILL BRING DEEP BROAD SWLY FLOW ALOFT. NAM/EC AND
GEFS MODEL/ENSEMBLE GUIDANCE HAS TRENDED TOWARD GOOD AGREEMENT FOR
A WAVE OF LOW PRESSURE TO DEVELOP OVER THE SE STATES WEDNESDAY /ALONG
THE STALLED OUT FRONT THAT/S PROGGED TO EXTEND NE TO THE NEW
JERSEY COAST/.
GFS /WHICH SEVERAL RUNS AGO...DISPLAYED PRACTICALLY THE LONE CHC
OF A LIGHT TO MODERATE WINTER WEATHER EVENT ACROSS OUR SE AND
PERHAPS CENTRAL CWA/ HAS BECOME ONE OF THE FEW OUTLIER SOLUTIONS.
/THE OTHER BEING THE 12Z CANADIAN GEM MODEL/.
12Z EC...18Z GEFS...AND THE 18Z/00Z NAM ARE IN PRETTY GOOD
AGREEMENT AND INDICATE THE POTENTIAL FOR A FEW TO SVRL INCHES OF
WET SNOW NEAR THE I-81 CORRIDOR. THE 21Z SREF HASN/T CHANGED MUCH
FROM THE 15Z VERSION...WITH THE NW EDGE OF ITS 0.25 INCH STORM
TOTAL LEQ QPF CONTOUR FROM KMRB...TO NEAR KMUI AND KABE.
THE COMPACT...OPEN /AND PERHAPS SLIGHTLY NEG TILT/ UPPER
SHORTWAVE THAT WILL BE LIFTING QUICKLY NE OUT OF THE SOUTHERN U.S.
WILL NOT HAVE A CHANCE TO AMPLIFY SIGNIFICANTLY...CONSIDERING THE
DEEP VORTEX DRIFTING OVER HUDSON BAY...WITH A FAST WESTERLY UPPER
FLOW ACROSS THE NRN U.S. AND UPPER GLAKES REGION. HOWEVER...THE
WELL- DEFINED ENTRANCE REGION OF A POTENT 140 KT UPPER JET FROM
PENN TO SRN NEW ENGLAND WILL HELP TO CREATE A POTENTIAL PERIOD OF
MODERATE TO STRONG UVVEL AS JET MAX WITH THE LIFTING SHORTWAVE
LINKS UP.
BUMPED UP POPS TO LIKELY ACROSS THE FAR SE WITH A TIGHT POP GRADIENT
BETWEEN I-81 AND A KAOO...KUNV AND KIPT LINE.
PRECIP TYPE WILL LIKELY START AS A COLD LIGHT RAIN IN THE
SOUTH...WITH SOME AREAS OF LIGHT RAIN/WET SNOW DEVELOPING FROM THE
HIGHER MID CLOUD BASE ACROSS THE REGION NORTHWEST OF I-81 BY LATE
EVENING.
MENTIONED THE CHC FOR A LIGHT TO MDT WET SNOW FOR OUR SE ZONES IN
THE HAZ WEATHER OUTLOOK.
MODELS REBOUND WITH BETTER CONSENSUS AFTER THIS SYSTEM HEADED INTO
THE WEEKEND. A NORTHERN STREAM COLD FRONT MOVES THROUGH FRI
TURNING FLOW WESTERLY AND BRINGING COLD AND BRISK CONDITIONS TO
START THE WEEKEND. TEMPS WILL BE ABOUT 5F BELOW NORMAL /WHICH WILL
BE NOTICEABLE AFTER OUR RUN OF RELATIVELY MILD TEMPS/ AND LAKE
EFFECT/OROGRAPHIC SNOW SHOWERS WILL DEVELOP FRI NIGHT INTO
SAT...MAINLY CONFINED TO THE NW MTNS.
HIGH PRES RETURNS FOR SUNDAY/MONDAY WHICH WILL ALLOW TEMPERATURES TO
GRADUALLY MODERATE WITH FAIR WEATHER.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
A COLD FRONT...LOCATED EXTENDING ACROSS THE WESTERN HALF OF PA AT
07Z...WILL PUSH SLOWLY SOUTHEAST ACROSS PENNSYLVANIA LATE
TONIGHT...ACCOMPANIED BY OCNL LGT RAIN. CURRENT ANALYSIS SHOWS IFR
CONDS CONFINED TO NW PA...BEHIND FRONT. HOWEVER...AS THE FRONT
PUSHES EAST...EXPECT DETERIORATING FLYING CONDS TO SPREAD OVER THE
REST OF PA. SHORT RANGE MDL DATA SUPPORTS IFR CONDS BECOMING
WIDESPREAD ACROSS THE REST OF CENTRAL PA AFTER 09Z.
MODEST IMPROVEMENT IS EXPECTED BY TUESDAY AFTN...AS FRONT BEGINS TO
PUSH EAST OF THE REGION. MANY LOCATIONS WILL LIKELY IMPROVE TO
MVFR CONDS. HOWEVER...RESIDUAL MOISTURE ASCENDING THE W MTNS COULD
LEAD TO LINGERING IFR CIGS AT JST AND BFD THRU TUE NIGHT.
OUTLOOK...
WED...AM LOW CIGS POSSIBLE W MTNS.
WED NIGHT...RAIN/SNOW AND LOW CIGS POSSIBLE SOUTHEAST.
THU...NO SIG WX EXPECTED.
FRI...PM SHSN POSSIBLE NW MTNS.
SAT...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT/STEINBUGL
NEAR TERM...LAMBERT/STEINBUGL
SHORT TERM...DANGELO/LAMBERT
LONG TERM...LAMBERT/RXR/STEINBUGL
AVIATION...FITZGERALD/CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1254 AM EST TUE DEC 6 2011
.SYNOPSIS...
A MOIST SOUTHWEST FLOW ALOFT WILL INTERACT WITH A SLOW MOVING
WAVY FRONTAL BOUNDARY TO BRING UNSETTLED CONDITIONS TO THE AREA
THROUGH MID WEEK. UPPER LEVEL ENERGY MIGRATING FROM THE ROCKIES
EASTWARD ACROSS THE CENTRAL PLAINS STATES INTO THE APPALACHIANS
SHOULD INDUCE A MORE DEFINED AREA OF LOW PRESSURE OVER THE
SOUTHERN MID-ATLANTIC REGION BY WEDNESDAY NIGHT BEFORE LIFTING
NORTHEAST OFF THE SOUTHERN NEW ENGLAND COAST EARLY THURSDAY
MORNING. COLD AND BRISK WEATHER IS ANTICIPATED FROM LATER THIS
WEEK INTO THE FIRST PART OF THE WEEKEND...WITH SOME MODERATION
IN TEMPERATURES LIKELY HEADING INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
AT 0530Z THE SFC COLD FRONT WAS LOCATED JUST E OF A JHW-YNG-ZZV
LINE. RDR SHOWS GREATEST CVRG OR LGT/MOD RNFL MOVG ACRS THE NW
AND NCNTRL MTNS. MDL AND CIWS DATA SUGGEST PCPN WILL BECOME
DISORGANIZED THROUGH THE PREDAWN HOURS AS BEST MID/UPPER FORCING
SLIDES OFF TO THE NORTH AND FNTL WAVE LIFTS NEWD FM SW PA. WV/IR
SATL DATA ALSO SHOWS DRY SLOT SURGING NEWD INTO THE UPPER OH VLY
WHICH SHOULD ALSO HELP TO CUT OFF PCPN TO SOME EXTENT. AN
UNSEASONABLY MILD EARLY DEC NIGHT WILL CONTINUE OVR MUCH OF THE
CWA WITH READINGS IN THE MID 40S TO MID 50S. THE EXCEPTION WILL BE
OVR THE FAR NW AS COLDER AIR WRAPS IN FM THE NORTH. MARGINAL BL
AND LLVL WET BULBS SUGGEST A LOW CHANCE FOR RA/SN MIX WITH SFC
TEMPS BOTTOMING OUT IN THE MID TO UPPER 30S.
PREVIOUS DISC FROM 1059 PM...
SFC COLD FRONT HAS STALLED OUT TEMPORARILY THIS EVENING...JUST TO
THE SE OF INTERSTATE 90 IN FAR NWRN PENN. 03Z SFC OBS...AND THE 02Z
RUC DISPLAY A VERY TIGHT...MEAN SFC-925 MB TEMP GRADIENT FROM
KERI...SW TO KCMH. RUC INDICATES THAT THIS BOUNDARY WILL CRAWL
EAST TO NEAR A KELZ...TO KDUJ AND KPIT LINE BY THE 10-12Z TUESDAY
TIMEFRAME.
THE RAIN AREA /THAT HAS BEEN STREAMING NE AND CONFINED NEAR...AND
JUST IN THE WAKE OF THE FRONT/ HAS STARTED TO QUICKLY EXPAND
EAST AHEAD OF THIS BOUNDARY /NEARING KUNV ATTM AND LIKELY
BEGINNING IN KIPT BY 05Z/...AS THE NOSE OF A STRENGTHENING
50-55KT/850 MB SWRLY JET MOVES NORTH ACROSS THE ALLEGHENY PLATEAU.
THIS LLJ ENERGY WILL BE AIDED BY INCREASING 850-700 UVVEL BENEATH
PULSES OF UPPER LEVEL DIVERGENCE BENEATH THE RIGHT ENTRANCE REGION
OF A 110 KT JET LIFTING INTO NEW YORK STATE TOWARD DAYBREAK.
RUC AND SREF MEAN...12-HOUR QPF IS AROUND 0.50 OF AN INCH ACROSS
OUR FAR NW ZONES /NEAR KBFD/...AND BETWEEN 0.10 AND 0.25 OF AN
INCH THROUGHOUT THE CENTRAL COUNTIES. RAINFL AMOUNTS OVER MUCH OF
THE LOWER SUSQUEHANNA VALLEY REGION WILL STAY AOB 0.10 IF AN INCH
THROUGH 12Z TUESDAY.
LATEST NAM/HRRR SPREADS THE PRECIP GRADUALLY TO THE EAST ACROSS
THE REST OF THE SCENT MTNS AND SUSQ VALLEY THROUGH THE PREDAWN
HOURS. TIMING OF HIGHEST CHCS FOR PRECIP IS BETWEEN 05-10Z TUES
ACROSS THE NW HALF OF THE CWA...AND DURING THE MID TO LATE MORNING
IN THE SE ZONES.
RUC 925 MB WET BULB TEMPS SINK TO A MIN OF ABOUT PLUS 1-2C ACROSS
THE FAR NW BY 12Z TUESDAY...SO A CHANG-OVER TO SLEET/WET SNOW IS
NOT EXPECTED AS FAR EAST AS WARREN OR KBFD.
POPS WILL DECREASE AROUND OR SHORTLY AFTER DAYBREAK TUESDAY IN THE
FAR NW. THE EXTENSIVE CLOUD COVER AND CONTINUED LIGHT SOUTH TO
SOUTHEAST SFC WINDS ACROSS MOST OF THE AREA SHOULD KEEP TEMPS FROM
FALLING VERY MUCH TONIGHT. TEMPS WILL FALL AN ADDITIONAL SEVERAL
DEG F ACROSS THE HIGHER TERRAIN OF THE NORTH AND WEST...BUT WILL
BE STEADY OR FALL JUST A FEW DEGREES ELSEWHERE AS MOISTURE BUILDS
AND CLOUDS LOWER SUBSTANTIALLY. WILL JUST MENTION PATCHY 2-3SM FOG
IN THE WHOLE AREA FOR THE TIME BEING.
&&
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
FRONT INCHES IT/S WAY ACROSS THE REST OF CENTRAL/ERN PENN
ON TUES. NO SIGNIFICANT WAVES DEVELOP ALONG IT...SO GENERALLY SCT
SHRA WILL FALL THROUGH THE DAY ON TUESDAY. LIKELIHOOD OF SHOWERS
FAIRLY HIGH DURING THE WHOLE DAY...AND PINNING A TIME FOR HIGHEST
POPS NOT EASY. WILL PAINT THE HIGHER POPS IN THE AFTN AS PRESSURE
LOWER ON THE FRONT SLIGHTLY. THE MORE-ORGANIZED SHOWERS AND HIGHER
POPS SHOULD BE IN THE SERN HALF OF THE FORECAST AREA. UPPER TROUGH
STAYS HIGHLY POSITIVE AND DRAGS ALONG. THUS...LITTLE CHANGE IN THE
SFC PATTERN AND FORCING IS SEEN FOR EARLY TUES NIGHT.
HOWEVER...THE SFC BOUNDARY DOES SEEM TO CLEAR THE FORECAST AREA
TUES NIGHT...AND WILL LOWER POPS OVER MUCH OF THE AREA IN THE
SECOND HALF OF THE NIGHT. UPSLOPE IN THE WEST COULD FORCE ENOUGH
MOISTURE UP INTO THE HILLS TO GENERATE SHOWERS...BUT P-TYPE IS
QUESTIONABLE. 8H TEMPS ARE ABOVE FZG THROUGH 06-09Z IN THE WRN
HIGHLANDS...BUT SFC TEMPS SHOULD FOLLOW ALONG IN LOCK STEP AND GET
INTO THE 20S NW AND NEAR FZG IN THE LAURELS. WILL THEREFORE
MENTION SHSN MIXING IN TO THE SCT SHRA IN THE W AFTER MIDNIGHT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
A POSITIVE TILTED LONG WAVE TROUGH EXTENDING FROM THE GREAT LAKES
INTO TX ON WED WILL BRING DEEP BROAD SWLY FLOW ALOFT. NAM/EC AND
GEFS MODEL/ENSEMBLE GUIDANCE HAS TRENDED TOWARD GOOD AGREEMENT FOR
A WAVE OF LOW PRESSURE TO DEVELOP OVER THE SE STATES WEDNESDAY /ALONG
THE STALLED OUT FRONT THAT/S PROGGED TO EXTEND NE TO THE NEW
JERSEY COAST/.
GFS /WHICH SEVERAL RUNS AGO...DISPLAYED PRACTICALLY THE LONE CHC
OF A LIGHT TO MODERATE WINTER WEATHER EVENT ACROSS OUR SE AND
PERHAPS CENTRAL CWA/ HAS BECOME ONE OF THE FEW OUTLIER SOLUTIONS.
/THE OTHER BEING THE 12Z CANADIAN GEM MODEL/.
12Z EC...18Z GEFS...AND THE 18Z/00Z NAM ARE IN PRETTY GOOD
AGREEMENT AND INDICATE THE POTENTIAL FOR A FEW TO SVRL INCHES OF
WET SNOW NEAR THE I-81 CORRIDOR. THE 21Z SREF HASN/T CHANGED MUCH
FROM THE 15Z VERSION...WITH THE NW EDGE OF ITS 0.25 INCH STORM
TOTAL LEQ QPF CONTOUR FROM KMRB...TO NEAR KMUI AND KABE.
THE COMPACT...OPEN /AND PERHAPS SLIGHTLY NEG TILT/ UPPER
SHORTWAVE THAT WILL BE LIFTING QUICKLY NE OUT OF THE SOUTHERN U.S.
WILL NOT HAVE A CHANCE TO AMPLIFY SIGNIFICANTLY...CONSIDERING THE
DEEP VORTEX DRIFTING OVER HUDSON BAY...WITH A FAST WESTERLY UPPER
FLOW ACROSS THE NRN U.S. AND UPPER GLAKES REGION. HOWEVER...THE
WELL- DEFINED ENTRANCE REGION OF A POTENT 140 KT UPPER JET FROM
PENN TO SRN NEW ENGLAND WILL HELP TO CREATE A POTENTIAL PERIOD OF
MODERATE TO STRONG UVVEL AS JET MAX WITH THE LIFTING SHORTWAVE
LINKS UP.
BUMPED UP POPS TO LIKELY ACROSS THE FAR SE WITH A TIGHT POP GRADIENT
BETWEEN I-81 AND A KAOO...KUNV AND KIPT LINE.
PRECIP TYPE WILL LIKELY START AS A COLD LIGHT RAIN IN THE
SOUTH...WITH SOME AREAS OF LIGHT RAIN/WET SNOW DEVELOPING FROM THE
HIGHER MID CLOUD BASE ACROSS THE REGION NORTHWEST OF I-81 BY LATE
EVENING.
MENTIONED THE CHC FOR A LIGHT TO MDT WET SNOW FOR OUR SE ZONES IN
THE HAZ WEATHER OUTLOOK.
MODELS REBOUND WITH BETTER CONSENSUS AFTER THIS SYSTEM HEADED INTO
THE WEEKEND. A NORTHERN STREAM COLD FRONT MOVES THROUGH FRI
TURNING FLOW WESTERLY AND BRINGING COLD AND BRISK CONDITIONS TO
START THE WEEKEND. TEMPS WILL BE ABOUT 5F BELOW NORMAL /WHICH WILL
BE NOTICEABLE AFTER OUR RUN OF RELATIVELY MILD TEMPS/ AND LAKE
EFFECT/OROGRAPHIC SNOW SHOWERS WILL DEVELOP FRI NIGHT INTO
SAT...MAINLY CONFINED TO THE NW MTNS.
HIGH PRES RETURNS FOR SUNDAY/MONDAY WHICH WILL ALLOW TEMPERATURES TO
GRADUALLY MODERATE WITH FAIR WEATHER.
&&
.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
A COLD FRONT...LOCATED OVER NW PA AT 03Z...WILL PUSH SLOWLY
SOUTHEAST ACROSS PENNSYLVANIA LATE TONIGHT...ACCOMPANIED BY OCNL
LGT RAIN. CURRENT ANALYSIS SHOWS IFR CONDS CONFINED TO NW
PA...BEHIND FRONT. HOWEVER...AS THE FRONT PUSHES EAST...EXPECT
DETERIORATING FLYING CONDS TO SPREAD OVER THE REST OF PA. SHORT
RANGE MDL DATA SUPPORTS IFR CONDS DEVELOPING AT BFD BY 06Z...THEN
BECOMING WIDESPREAD ACROSS THE REST OF CENTRAL PA TOWARDS DAWN.
MODEST IMPROVEMENT IS EXPECTED BY TUESDAY AFTN...AS FRONT BEGINS TO
PUSH EAST OF THE REGION. MANY LOCATIONS WILL LIKELY IMPROVE TO
MVFR CONDS. HOWEVER...RESIDUAL MOISTURE ASCENDING THE W MTNS COULD
LEAD TO LINGERING IFR CIGS AT JST AND BFD THRU TUE NIGHT.
OUTLOOK...
WED...AM LOW CIGS POSSIBLE W MTNS.
WED NIGHT...RAIN/SNOW AND LOW CIGS POSSIBLE SOUTHEAST.
THU...NO SIG WX EXPECTED.
FRI...PM SHSN POSSIBLE NW MTNS.
SAT...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT/STEINBUGL
NEAR TERM...LAMBERT/STEINBUGL
SHORT TERM...DANGELO/LAMBERT
LONG TERM...LAMBERT/RXR/STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1152 PM EST MON DEC 5 2011
.SYNOPSIS...
A MOIST SOUTHWEST FLOW ALOFT WILL INTERACT WITH A SLOW MOVING
FRONTAL BOUNDARY AND ONE OR MORE WAVES OF LOW PRESSURE TO BRING
UNSETTLED CONDITIONS TO THE AREA THROUGH MID WEEK. COLD AND BRISK
WEATHER IS ANTICIPATED FROM LATER THIS WEEK INTO THE WEEKEND.
&&
.NEAR TERM /UNTIL 8 AM TUESDAY MORNING/...
SFC COLD FRONT HAS STALLED OUT TEMPORARILY THIS EVENING...JUST TO
THE SE OF INTERSTATE 90 IN FAR NWRN PENN. 03Z SFC OBS...AND THE 02Z
RUC DISPLAY A VERY TIGHT...MEAN SFC-925 MB TEMP GRADIENT FROM
KERI...SW TO KCMH. RUC INDICATES THAT THIS BOUNDARY WILL CRAWL
EAST TO NEAR A KELZ...TO KDUJ AND KPIT LINE BY THE 10-12Z TUESDAY
TIMEFRAME.
THE RAIN AREA /THAT HAS BEEN STREAMING NE AND CONFINED NEAR...AND
JUST IN THE WAKE OF THE FRONT/ HAS STARTED TO QUICKLY EXPAND
EAST AHEAD OF THIS BOUNDARY /NEARING KUNV ATTM AND LIKELY
BEGINNING IN KIPT BY 05Z/...AS THE NOSE OF A STRENGTHENING
50-55KT/850 MB SWRLY JET MOVES NORTH ACROSS THE ALLEGHENY PLATEAU.
THIS LLJ ENERGY WILL BE AIDED BY INCREASING 850-700 UVVEL BENEATH
PULSES OF UPPER LEVEL DIVERGENCE BENEATH THE RIGHT ENTRANCE REGION
OF A 110 KT JET LIFTING INTO NEW YORK STATE TOWARD DAYBREAK.
RUC AND SREF MEAN...12-HOUR QPF IS AROUND 0.50 OF AN INCH ACROSS
OUR FAR NW ZONES /NEAR KBFD/...AND BETWEEN 0.10 AND 0.25 OF AN
INCH THROUGHOUT THE CENTRAL COUNTIES. RAINFL AMOUNTS OVER MUCH OF
THE LOWER SUSQUEHANNA VALLEY REGION WILL STAY AOB 0.10 IF AN INCH
THROUGH 12Z TUESDAY.
LATEST NAM/HRRR SPREADS THE PRECIP GRADUALLY TO THE EAST ACROSS
THE REST OF THE SCENT MTNS AND SUSQ VALLEY THROUGH THE PREDAWN
HOURS. TIMING OF HIGHEST CHCS FOR PRECIP IS BETWEEN 05-10Z TUES
ACROSS THE NW HALF OF THE CWA...AND DURING THE MID TO LATE MORNING
IN THE SE ZONES.
RUC 925 MB WET BULB TEMPS SINK TO A MIN OF ABOUT PLUS 1-2C ACROSS
THE FAR NW BY 12Z TUESDAY...SO A CHANG-OVER TO SLEET/WET SNOW IS
NOT EXPECTED AS FAR EAST AS WARREN OR KBFD.
POPS WILL DECREASE AROUND OR SHORTLY AFTER DAYBREAK TUESDAY IN THE
FAR NW. THE EXTENSIVE CLOUD COVER AND CONTINUED LIGHT SOUTH TO
SOUTHEAST SFC WINDS ACROSS MOST OF THE AREA SHOULD KEEP TEMPS FROM
FALLING VERY MUCH TONIGHT. TEMPS WILL FALL AN ADDITIONAL SEVERAL
DEG F ACROSS THE HIGHER TERRAIN OF THE NORTH AND WEST...BUT WILL
BE STEADY OR FALL JUST A FEW DEGREES ELSEWHERE AS MOISTURE BUILDS
AND CLOUDS LOWER SUBSTANTIALLY. WILL JUST MENTION PATCHY 2-3SM FOG
IN THE WHOLE AREA FOR THE TIME BEING.
&&
.SHORT TERM /8 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
FRONT INCHES IT/S WAY ACROSS THE REST OF CENTRAL/ERN PENN
ON TUES. NO SIGNIFICANT WAVES DEVELOP ALONG IT...SO GENERALLY SCT
SHRA WILL FALL THROUGH THE DAY ON TUESDAY. LIKELIHOOD OF SHOWERS
FAIRLY HIGH DURING THE WHOLE DAY...AND PINNING A TIME FOR HIGHEST
POPS NOT EASY. WILL PAINT THE HIGHER POPS IN THE AFTN AS PRESSURE
LOWER ON THE FRONT SLIGHTLY. THE MORE-ORGANIZED SHOWERS AND HIGHER
POPS SHOULD BE IN THE SERN HALF OF THE FORECAST AREA. UPPER TROUGH
STAYS HIGHLY POSITIVE AND DRAGS ALONG. THUS...LITTLE CHANGE IN THE
SFC PATTERN AND FORCING IS SEEN FOR EARLY TUES NIGHT.
HOWEVER...THE SFC BOUNDARY DOES SEEM TO CLEAR THE FORECAST AREA
TUES NIGHT...AND WILL LOWER POPS OVER MUCH OF THE AREA IN THE
SECOND HALF OF THE NIGHT. UPSLOPE IN THE WEST COULD FORCE ENOUGH
MOISTURE UP INTO THE HILLS TO GENERATE SHOWERS...BUT P-TYPE IS
QUESTIONABLE. 8H TEMPS ARE ABOVE FZG THROUGH 06-09Z IN THE WRN
HIGHLANDS...BUT SFC TEMPS SHOULD FOLLOW ALONG IN LOCK STEP AND GET
INTO THE 20S NW AND NEAR FZG IN THE LAURELS. WILL THEREFORE
MENTION SHSN MIXING IN TO THE SCT SHRA IN THE W AFTER MIDNIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
A POSITIVE TILTED LONG WAVE TROUGH EXTENDING FROM THE GREAT LAKES
INTO TX ON WED WILL BRING DEEP BROAD SWLY FLOW ALOFT. NAM/EC AND
GEFS MODEL/ENSEMBLE GUIDANCE HAS TRENDED TOWARD GOOD AGREEMENT FOR
A WAVE OF LOW PRESSURE TO DEVELOP OVER THE SE STATES WEDNESDAY /ALONG
THE STALLED OUT FRONT THAT/S PROGGED TO EXTEND NE TO THE NEW
JERSEY COAST/.
GFS /WHICH SEVERAL RUNS AGO...DISPLAYED PRACTICALLY THE LONE CHC
OF A LIGHT TO MODERATE WINTER WEATHER EVENT ACROSS OUR SE AND
PERHAPS CENTRAL CWA/ HAS BECOME ONE OF THE FEW OUTLIER SOLUTIONS.
/THE OTHER BEING THE 12Z CANADIAN GEM MODEL/.
12Z EC...18Z GEFS...AND THE 18Z/00Z NAM ARE IN PRETTY GOOD
AGREEMENT AND INDICATE THE POTENTIAL FOR A FEW TO SVRL INCHES OF
WET SNOW NEAR THE I-81 CORRIDOR. THE 21Z SREF HASN/T CHANGED MUCH
FROM THE 15Z VERSION...WITH THE NW EDGE OF ITS 0.25 INCH STORM
TOTAL LEQ QPF CONTOUR FROM KMRB...TO NEAR KMUI AND KABE.
THE COMPACT...OPEN /AND PERHAPS SLIGHTLY NEG TILT/ UPPER
SHORTWAVE THAT WILL BE LIFTING QUICKLY NE OUT OF THE SOUTHERN U.S.
WILL NOT HAVE A CHANCE TO AMPLIFY SIGNIFICANTLY...CONSIDERING THE
DEEP VORTEX DRIFTING OVER HUDSON BAY...WITH A FAST WESTERLY UPPER
FLOW ACROSS THE NRN U.S. AND UPPER GLAKES REGION. HOWEVER...THE
WELL- DEFINED ENTRANCE REGION OF A POTENT 140 KT UPPER JET FROM
PENN TO SRN NEW ENGLAND WILL HELP TO CREATE A POTENTIAL PERIOD OF
MODERATE TO STRONG UVVEL AS JET MAX WITH THE LIFTING SHORTWAVE
LINKS UP.
BUMPED UP POPS TO LIKELY ACROSS THE FAR SE WITH A TIGHT POP GRADIENT
BETWEEN I-81 AND A KAOO...KUNV AND KIPT LINE.
PRECIP TYPE WILL LIKELY START AS A COLD LIGHT RAIN IN THE
SOUT...WITH SOME AREAS OF LIGHT RAIN/WET SNOW DEVELOPING FROM THE
HIGHER MID CLOUD BASE ACROSS THE REGION NORTHWEST OF I-81 BY LATE
EVENING.
MENTIONED THE CHC FOR A LIGHT TO MDT WET SNOW FOR OUR SE ZONES IN
THE HAZ WEATHER OUTLOOK.
MODELS REBOUND WITH BETTER CONSENSUS AFTER THIS SYSTEM HEADED INTO
THE WEEKEND. A NORTHERN STREAM COLD FRONT MOVES THROUGH FRI
TURNING FLOW WESTERLY AND BRINGING COLD AND BRISK CONDITIONS TO
START THE WEEKEND. TEMPS WILL BE ABOUT 5F BELOW NORMAL /WHICH WILL
BE NOTICEABLE AFTER OUR RUN OF RELATIVELY MILD TEMPS/ AND LAKE
EFFECT/OROGRAPHIC SNOW SHOWERS WILL DEVELOP FRI NIGHT INTO
SAT...MAINLY CONFINED TO THE NW MTNS.
HIGH PRES RETURNS FOR SUNDAY/MONDAY WHICH WILL ALLOW TEMPERATURES TO
GRADUALLY MODERATE WITH FAIR WEATHER.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
A COLD FRONT...LOCATED OVER NW PA AT 03Z...WILL PUSH SLOWLY
SOUTHEAST ACROSS PENNSYLVANIA LATE TONIGHT...ACCOMPANIED BY OCNL
LGT RAIN. CURRENT ANALYSIS SHOWS IFR CONDS CONFINED TO NW
PA...BEHIND FRONT. HOWEVER...AS THE FRONT PUSHES EAST...EXPECT
DETERIORATING FLYING CONDS TO SPREAD OVER THE REST OF PA. SHORT
RANGE MDL DATA SUPPORTS IFR CONDS DEVELOPING AT BFD BY 06Z...THEN
BECOMING WIDESPREAD ACROSS THE REST OF CENTRAL PA TOWARDS DAWN.
MODEST IMPROVEMENT IS EXPECTED BY TUESDAY AFTN...AS FRONT BEGINS TO
PUSH EAST OF THE REGION. MANY LOCATIONS WILL LIKELY IMPROVE TO
MVFR CONDS. HOWEVER...RESIDUAL MOISTURE ASCENDING THE W MTNS COULD
LEAD TO LINGERING IFR CIGS AT JST AND BFD THRU TUE NIGHT.
OUTLOOK...
WED...AM LOW CIGS POSSIBLE W MTNS.
WED NIGHT...RAIN/SNOW AND LOW CIGS POSSIBLE SOUTHEAST.
THU...NO SIG WX EXPECTED.
FRI...PM SHSN POSSIBLE NW MTNS.
SAT...NO SIG WX EXPECTED.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...DANGELO/LAMBERT
LONG TERM...LAMBERT/RXR/STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
756 PM CST WED DEC 7 2011
.DISCUSSION...
WENT AHEAD AND INCREASE LOWS ABOUT 5 TO 8 DEGREES IN MOST SPOTS AS
CLOUD COVER NOW SEEMS TO BE LOCKED IN FOR THE NIGHT...ESPECIALLY
WITH THE APPROACH OF THE UPPER LEVEL WAVE IN THE NORTHERN ROCKIES.
SO...BASICALLY LOOKING AT TEMPERATURES RANGING FROM AROUND THE MID
TEENS TO LOWER 20S. DID ADD SOME FLURRIES AND A SLIGHT CHANCE FOR
LIGHT SNOW IN THE FAR SOUTHERN CWA FRO 9-12Z AS THE RUC AND HRRR
CONTINUE TO INDICATE THAT SOME SNOWFALL MAY GET SQUEEZED OUT OF THE
MID LEVEL DECK MOVING SOUTHWARD. THIS DOES NOT SEEM COMPLETELY OUT
OF THE QUESTION SINCE THE THERMAL PROFILE BECOMES MORE DENDRITIC IN
THE STRONGER FORCING AT THIS TIME AND OUR LOWEST LEVELS ARE NOT
COMPLETELY DRY SO COULD SEE SOME FLAKES WITH THE BETTER CHANCES NEAR
THE MISSOURI RIVER FROM ABOUT 9Z THROUGH 15Z. /08
&&
.PREV DISCUSSION.../ISSUED AT 252 PM CST/
FRONTAL BOUNDARY CONTINUES TO DROP SOUTHWARD ACROSS THE REGION THIS
AFTERNOON...AND WILL EXIT THE AREA BY THIS EVENING. MAIN CHALLENGE
TONIGHT WILL BE IN TEMPERATURES...WITH STRONG COLD AIR ADVECTION
BEHIND THE FRONT...MUTED BY CLOUD COVER EXPECTED TO BE OVER MUCH OF
THE AREA DURING THE OVERNIGHT HOURS. WITH BREAKS IN THE
CLOUDS...WILL SEE TEMPERATURES FLUCTUATE DEPENDING ON THE CLOUD
COVER...THOUGH WILL SEE A GENERAL DOWNWARD TREND THROUGH THE NIGHT
WITH LOWS JUST UNDER 10 THROUGH THE HURON TO BROOKINGS CORRIDOR...TO
THE MID TEENS ALONG THE MISSOURI RIVER CORRIDOR WHERE CLOUDS WILL BE
MORE DOMINANT.
MODELS CONTINUING SLIGHT SOUTHWARD TREND WITH PRECIP CHANCES ON
THURSDAY...AS NORTHERN STREAM WAVE DROPS SOUTHEAST INTO THE NORTHERN
PLAINS. 700MB FRONTOGENESIS STILL HUGS THE MISSOURI RIVER VALLEY...
HOWEVER MOST MODELS SHOWING A DRY LAYER IN THE ATMOSPHERE NORTH OF
THE RIVER THAT WILL LIMIT NORTHWARD EXTENT OF ACCUMULATING PRECIP.
HAVE SCALED POPS BACK TO JUST OUR FAR SOUTHERN AREAS...GENERALLY
SOUTH OF LAKE ANDES/KYKN/KSLB LINE...WITH JUST A FEW TENTHS OF SNOW
AT BEST IN THESE AREAS. 850MB BAROCLINIC ZONE LINGERS FROM NORTH
CENTRAL NEBRASKA INTO SOUTHWEST SOUTH DAKOTA INTO THE EVENING AS THE
MAIN WAVE DROPS THROUGH THE DAKOTAS....AND THIS COULD KEEP SOME
LIGHT SNOW OR FLURRIES GOING JUST TO OUR SOUTHWEST INTO THURSDAY
EVENING. WILL KEEP IT DRY IN OUR AREA...THOUGH SOME MID CLOUDS WILL
LIKELY HANG AROUND IN THE WESTERN PORTIONS OF THE MISSOURI RIVER
VALLEY THROUGH 06Z BEFORE DRIER MID LEVEL AIR PUSHES SOUTH WITH THE
WAVE.
FOCUS FOR THE REMAINDER OF THE WEEK AND INTO THE WEEKEND WILL BE ON
TEMPERATURES...WITH POTENTIAL FOR SOME DECENT RADIATIONAL NIGHTTIME
COOLING. SURFACE RIDGE AXIS SHIFTS INTO NEBRASKA SO WILL LIKELY NOT
SEE WINDS GO COMPLETELY CALM EXCEPT IN MORE SHELTERED AREAS. HOWEVER
EVEN WITH RELATIVELY LIGHT WEST-SOUTHWEST WINDS EXPECTED OVER THE
SNOWPACK AREAS...SHOULD SEE QUICK EVENING DROPS IN TEMPERATURES
ACROSS OUR SOUTHEAST THURSDAY AND FRIDAY NIGHTS...WITH NON-DIURNAL
RISE IN TEMPERATURES EXPECTED LATER FRIDAY NIGHT AS WINDS/CLOUDS
INCREASE AHEAD OF WARM FRONT. DAYTIME TEMPERATURES SHOULD SEE
GRADUAL DECREASE IN EFFECT OF SNOWPACK ON READINGS...THOUGH COULD
STILL HOLD HIGHS BACK A FEW DEGREES ON FRIDAY WITH FULL SUNSHINE AND
LIMITED MIXING.
LONGER RANGE STILL LOOKS RELATIVELY DRY THROUGH TUESDAY...WITH
MODELS SHOWING DECENT AGREEMENT DIGGING YET ANOTHER WAVE INTO THE
SOUTHWEST CONUS WHILE SEPARATE NORTHERN STREAM TROUGH SLIDES EAST
ACROSS THE CANADIAN BORDER. WEAK WAVE SEEN EJECTING OUT OF SOUTHWEST
SYSTEM INTO THE MIDDLE MISSOURI VALLEY ON MONDAY. FORECAST SOUNDINGS
QUITE SPARSE ON MOISTURE ABOVE 850MB...BUT SIMILAR IN SHOWING STRONG
NORTHWARD PUSH OF LOW LEVEL MOISTURE/STRATUS AHEAD OF COLD FRONT IN
THE LATE NIGHT/MORNING HOURS. MOISTURE PROFILES FROM ALL MODELS ARE
REMINISCENT OF DRIZZLE SOUNDINGS...WITH LACK OF MOISTURE IN CRITICAL
ICE-BEARING LAYER ALOFT...BUT TOUGH TO PINPOINT THREAT OF POTENTIAL
FREEZING PRECIP AT DAY 4-5 RANGE SO WILL JUST GO WITH MENTION OF
LIGHT RAIN/SNOW WITH SLIGHT CHANCE POPS IN OUR FAR SOUTHEAST DURING
THE DAY MONDAY.
GREATER DIFFERENCES IN THE MODELS ARISE BY THE MIDDLE OF NEXT WEEK
IN HANDLING OF NORTHERN STREAM TROUGH AS IT MOVES ACROSS THE GREAT
LAKES AND EASTERN CANADA...AS WELL AS SOUTHWEST CONUS CUTOFF. GFS
STRONGER/SLOWER WITH NORTHERN STREAM TROUGH WHILE ALSO MAINTAINING
STRONGER SOUTHWEST SYSTEM...WITH ANOTHER RELATIVELY WEAK WAVE
LIFTING NORTHEAST THROUGH THE PLAINS MIDWEEK. ECMWF ON THE OTHER
HAND IS SLIGHTLY WEAKER/FASTER WITH THE NORTHERN STREAM TROUGH...
ALLOWING STRONGER CHUNK OF ENERGY TO LIFT NORTHEAST INTO THE PLAINS
ON WEDNESDAY. EITHER SCENARIO GIVES AT LEAST SOUTHERN PARTS OF OUR
AREA A CHANCE OF PRECIP LATE IN THE FORECAST PERIOD. MAIN DIFFERENCE
IS STRONGER ECMWF SPREADS THE PRECIP MUCH FARTHER NORTHEAST THAN THE
GFS. IN EITHER CASE...SEEMS SOME CHANCE POPS ARE WARRANTED FOR THE
DAY 7 TIMEFRAME AT THIS TIME. AFOREMENTIONED DIFFERENCES ALSO RESULT
IN DRASTICALLY DIFFERENT LOW LEVEL TEMPERATURE PROFILES...WITH ECMWF
PULLING WARMER AIR MUCH FARTHER NORTH THAN GFS WHERE NORTHERN STREAM
REMAINS DOMINANT. WITH RIDE WITH BLEND OF THE TWO SOLUTIONS AND KEEP
PRECIP TYPE AS ALL SNOW FOR NOW...BUT WARMER ECMWF COULD BRING A
THREAT OF LIQUID PRECIP INTO THE MIX AND WILL KEEP A CLOSE EYE ON
TRENDS FOR THIS OVER THE NEXT FEW DAYS.
&&
.AVIATION.../FOR THE 00Z TAF ISSUANCE/
GENERAL VFR CONDITIONS EXPECTED THROUGH 00Z FRI. VERY SMALL THREAT
FOR MARGINAL MVFR STRATUS LATE TONIGHT AND EARLY MORNING BEHIND
COLD FRONT...BUT BELOW MENTIONABLE THRESHOLD...AT WHICH TIME A FEW
FLURRIES AT BEST FOR KSUX AREA...WHICH SHOULD NOT BREACH VFR IF THEY
EVEN CAN SURVIVE THE LOW LEVEL DRY AIR. /CHAPMAN
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BROWNSVILLE TX
1158 AM CST TUE DEC 6 2011
.DISCUSSION...SEE THE AVIATION SEGMENT BELOW FOR THE DISCUSSION OF
THE 18Z TAF ISSUANCE.
&&
.AVIATION...THE 12Z BRO SOUNDING SHOWS THAT THE CURRENT ATMS IS
PRETTY SATURATED AND A FAIRLY STRONG INVERSION IS EVIDENT AT AND
BELOW THE 850 MB LEVEL. AS A RESULT VSBL IMAGERY OVER DEEP SOUTH
TX SHOWS AN LARGE AREA OF OVC CLD DECKS. HOWEVER A LARGE HOLE IN
THE LOW CLD DECKS IS EVIDENT OVER SOUTH CENTRAL TX AND APPEARS TO
BE MOVING S-SE AT A PRETTY GOOD CLIP. THE LATEST RUC AND NAM12 RH
FIELDS SHOWS MUCH DRIER AIR FILTERING IN OVER THE REGION
THROUGHOUT THE EVENING AND OVERNIGHT HOURS WHICH WILL RESULT IN
THE LIFTING OF THE CEILINGS THROUGHOUT THE UPCOMING TAF PERIOD.
ACCORDINGLY EXPECT VFR VSBYS AND CEILINGS THROUGH 18Z TOMORROW
WITH LIGHT TO MODERATE NORTHERLY SURFACE FLOW PERSISTING AS THE
SURFACE RIDGING SPREADS OVER THE REGION.
&&
.PREV DISCUSSION... /ISSUED 427 AM CST TUE DEC 6 2011/
SHORT TERM /TODAY THROUGH WEDNESDAY/...THE UPPER TROUGH AXIS
CURRENTLY EXTENDING TO THE DESERT SOUTHWEST WILL LIFT OUT ACROSS
NORTH TEXAS LATE TUESDAY NIGHT. WEAK ISENTROPIC LIFT AHEAD OF THE
UPPER TROUGH WILL RESULT IN CLOUDY SKIES...COOL TEMPERATURES...AND
A SLIGHT CHANCE OF LIGHT RAIN/SPRINKLES THIS MORNING THROUGH EARLY
THIS AFTERNOON. CLOUDS WILL BEGIN TO DECREASE LATER THIS AFTERNOON
AND TONIGHT AS THE UPPER TROUGH LIFTS OUT OVER THE SOUTHERN
PLAINS. SURFACE HIGH PRESSURE WILL SETTLE INTO DEEP SOUTH TEXAS
LATE TONIGHT THROUGH WEDNESDAY. THE MAIN CHALLENGE WILL BE HOW LOW
THE TEMPERATURES DROP TONIGHT/WEDNESDAY MORNING. LIGHT WINDS...
CLEARING SKIES...AND MUCH DRIER AIR FILTERING INTO THE AREA WOULD
SUGGEST A COLD NIGHT IN DEEP SOUTH TEXAS AND IN THE RIO GRANDE
VALLEY. CURRENT MODEL DATA CONSENSUS IS ALSO INDICATING A COLD
NIGHT ACROSS THE AREA. THE ONLY CONCERN IS THAT THE WINDS MAY NOT
DROP OFF AS QUICKLY AS THE MODEL GUIDANCE IS INDICATING. AFTER A
LONG IN OFFICE DISCUSSION...PONDERING OVER THE AVAILABLE GUIDANCE
ONE LAST TIME...AND COORDINATING WITH WFO CRP...HAVE DECIDED TO
ISSUE A FREEZE WATCH FOR A GOOD PORTION OF THE CWA. THE FREEZE
WATCH WILL INCLUDE ALL OF THE COUNTIES OF BRO CWA EXCEPT FOR
HIDALGO AND CAMERON COUNTIES AND THE COASTAL PORTION OF WILLACY
COUNTY. WIDESPREAD TEMPERATURES ARE EXPECTED TO BE IN THE UPPER
20S TO LOWER 30S ACROSS DEEP SOUTH TEXAS AND THE VALLEY WEDNESDAY
MORNING. PLEASE REFER TO THE NPW BRO PRODUCT.
THANKS WFO CORPUS CHRISTI FOR THE COORDINATION REGARDING THE FREEZE
WATCH.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...CLEAR SKIES WILL
COMBINE WITH LIGHT WINDS AND DRIER AIR TO PRODUCE ANOTHER ROUND OF
FREEZING TEMPERATURES ACROSS MOST OF DEEP SOUTH TEXAS AND THE RIO
GRANDE VALLEY LATE WEDNESDAY NIGHT THROUGH EARLY THURSDAY MORNING
.AND A FREEZE WARNING MAY BE NEEDED FOR THAT TIME. PLEASANT AND
DRY WEATHER WITH MODERATING TEMPERATURES IS EXPECTED THURSDAY AND
THURSDAY NIGHT AS SURFACE HIGH PRESSURE YIELDS TO AN INVERTED
SURFACE TROUGH OF LOW PRESSURE DEVELOPING OVER THE WESTERN GULF OF
MEXICO. ISOLATED TO SCATTERED AREAS OF RAIN WITH OVERCAST SKIES
WILL THEN PREVAIL FOR FRIDAY THROUGH EARLY NEXT WEEK AS THE TROUGH
INTENSIFIES AND PERSISTS. TEMPERATURES WILL BE HELD AT BELOW NORMAL
LEVELS FROM FRIDAY THROUGH SUNDAY DUE TO THE INCREASED CLOUD COVER
AND FLOW FROM THE NORTHEAST AND EAST...HOWEVER TEMPERATURES WILL
BEGIN TO RECOVER ON MONDAY AS THE FLOW SHIFTS FROM OUT OF THE
SOUTHEAST.
MARINE...TODAY THROUGH WEDNESDAY...OBS AT BUOY 020 CURRENTLY
REFLECT NNW WINDS AT AROUND 19 KNOTS WITH HIGHER GUSTS AND WAVE
HEIGHTS AROUND 7 FEET WITH A 5 SECOND PERIOD. STRONG WINDS WILL
PERSIST TODAY AS HIGH PRESSURE CONTINUES TO SURGE ACROSS THE LOWER
TEXAS COAST. THE SMALL CRAFT ADVISORY ON THE BAY IS IN EFFECT UNTIL
1 PM TODAY AND MAY LIKELY BE EXTENDED THROUGH LATE THIS AFTERNOON
OR INTO EARLY THIS EVENING. A SMALL CRAFT ADVISORY HAS BEEN
EXTENDED ON THE GULF WATERS THROUGH 6 AM WEDNESDAY. LITTLE CHANGE
IS OTHERWISE EXPECTED IN THE SHORT TERM MARINE FORECAST.
WEDNESDAY NIGHT THROUGH MONDAY...MARINE CONDITIONS ARE EXPECTED TO
STEADILY IMPROVE WEDNESDAY NIGHT THROUGH FRIDAY...WITH SMALL CRAFT
ADVISORIES NOT ANTICIPATED TO BE NEEDED...AS SURFACE HIGH PRESSURE
SHIFTS EAST FROM THE TEXAS COASTLINE TO THE MID-ATLANTIC REGION.
WINDS AND SEAS WILL THEN INCREASE FOR FRIDAY NIGHT THROUGH EARLY
NEXT WEEK...WITH SMALL CRAFT ADVISORIES INCREASINGLY POSSIBLE...AS
THE HIGH PRESSURE SYSTEM INTERACTS WITH LOW PRESSURE OVER THE BAY
OF CAMPECHE AND SOUTHERN GULF OF MEXICO.
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...FREEZE WATCH FROM LATE TONIGHT THROUGH WEDNESDAY MORNING FOR
TXZ248>252-254.
GM...SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM CST THIS AFTERNOON FOR
GMZ130-132-135.
SMALL CRAFT ADVISORY UNTIL 6 AM CST WEDNESDAY FOR GMZ150-155-170-
175.
&&
$$
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WWW.WEATHER.GOV/BROWNSVILLE
SHORT TERM...60
LONG TERM...54
GRAPHICAST/UPPER AIR...VEGA
AREA FORECAST DISCUSSION...UPDATED
NWS LUBBOCK TX
1141 PM CST MON DEC 5 2011
.AVIATION...
UNCERTAINTY REMAINS HIGH AS TO WHEN SNOW WILL END AT KLBB AND WHAT
CEILINGS WILL DO ONCE THE SNOW ENDS. OCCASIONAL PERIODS OF SNOW
CONTINUE AT KLBB AS BANDS REDEVELOP NEAR THE TERMINAL BUT CEILINGS
HAVE BEEN FAIRLY CONSISTENT. ALL INDICATIONS ARE THAT MVFR
CONDITIONS WILL CONTINUE THROUGH THE OVERNIGHT HOURS AND SNOW
SHOULD FINALLY SHUT OFF A FEW HOURS AFTER MIDNIGHT LOCAL TIME.
EXPECT TO SEE VFR CEILINGS DEVELOP BY MID-MORNING TUESDAY AND
CONTINUE THROUGH THE END OF THIS TAF CYCLE.
JORDAN
&&
.PREV DISCUSSION... /ISSUED 604 PM CST MON DEC 5 2011/
AVIATION...
SNOW HAS LET UP AT KLBB AND CEILINGS HAVE GONE VFR BRIEFLY...
HOWEVER EXPECT THAT WE WILL CONTINUE TO SEE PERIODS OF SNOW AT
KLBB AND CEILINGS BOUNCING AROUND MVFR TO VFR THROUGH THE
OVERNIGHT HOURS. IFR CONDITIONS ARE HARD TO FIGURE OUT RIGHT NOW
AT KLBB BUT FEEL THE CEILINGS SHOULD REMAIN ABOVE THIS. EXPECT
SNOW TO END AT KLBB BEFORE MIDNIGHT ALTHOUGH PERIODS OF LIGHT
FLURRIES MAY PERSIST INTO TUESDAY MORNING. KCDS SHOULD REMAIN VFR
WITH NO PRECIPITATION ALTHOUGH THERE MAY BE BRIEF PERIODS OF MVFR
THROUGH THE OVERNIGHT HOURS. EXPECT VFR CONDITIONS BY LATE
TOMORROW MORNING INTO EARLY TUESDAY AFTERNOON FOR KLBB.
JORDAN
PREV DISCUSSION... /ISSUED 334 PM CST MON DEC 5 2011/
SHORT TERM...
THE MAIN FOCUS FOR THE SHORT TERM WILL CONTINUE TO BE THE WINTER
WEATHER IMPACTS ASSOCIATED WITH A STRONG UPPER-LOW PRESSURE SYSTEM
STILL PUSHING THROUGH THE FOUR CORNERS REGION. OVER THE COURSE OF
THE DAY...LIGHT SNOW SHOWERS HAVE PERSISTED ACROSS THE
CAPROCK...THOUGH VERY MINOR ACCUMULATIONS HAVE OCCURRED SINCE THE
MID-MORNING HOURS. HOWEVER...CURRENT OBS...SATELLITE AND RADAR
IMAGERY AND MODEL PROJECTIONS ARE SHOWING THE POTENTIAL FOR SOME
ADDITIONAL AREAS OF LIGHT SNOWFALL TO MOVE INTO THE AREA LATE THIS
AFTERNOON AND THIS EVENING AS ANOTHER LOBE OF ENERGY FROM THE
AFOREMENTIONED UPPER-LOW ROTATES OVER THE REGION. MOST OF THE QPF
SIGNALS SHOWN ARE FAIRLY LIGHT...BUT THE TTU WRF AND THE HRRR BOTH
SHOW SOME ENHANCED PRECIPITATION BANDS DEVELOPING ACROSS THE
NORTHWESTERN ZONES THIS EVENING. THIS THINKING SEEMS TO BE PLAUSIBLE
AS IR SATELLITE DATA IS INDICATING A BAND OF COLDER CLOUD TOPS
PUSHING INTO THE WESTERN PANHANDLE...WITH SURFACE OBS AT CLOVIS
DROPPING DOWN TO 1-2 SM DUE TO SNOW. THUS...SOME LOCALIZED BURSTS OF
MODERATE SNOW WILL BE POSSIBLE /PARTICULARLY ACROSS THE SW
PANHANDLE/ WHERE AN ADDITIONAL INCH OF SNOW MAY BE POSSIBLE TONIGHT.
HAVE INCREASED POPS TO LIKELY TO CHANCE ACROSS MUCH OF THE AREA THIS
EVENING...BEFORE LOWERING THEM AFTER MIDNIGHT AS PRECIPITATION
BEGINS TO WANE.
THE OTHER BIG CONCERN FOR THIS EVENING WILL BE THE BRISK NORTHERLY
WINDS AND STRONG COLD AIR ADVECTION OCCURRING...WHICH WILL DROP
TEMPERATURES INTO THE SINGLE DIGITS ACROSS THE SW PANHANDLE AND INTO
THE TEENS ACROSS THE REST OF THE AREA. GIVEN THE BITTERLY COLD
TEMPERATURES AND WINDS THAT SHOULD REMAIN ABOVE 10 MPH OVERNIGHT
SOME LOW WIND CHILLS WILL DEVELOP AFTER SUNSET. GIVEN THE POTENTIAL
FOR SOME DANGEROUSLY COLD WINDS CHILLS AT OR AROUND -5 DEGREES
OCCURRING LATER TONIGHT ACROSS THE NORTHWEST ZONES...HAVE PLACED
THAT AREA IN A WIND CHILL ADVISORY THROUGH 15Z TOMORROW. GIVEN THE
POTENTIAL FOR SOME ADDITIONAL /ALBEIT GENERALLY LIGHT/ SNOWFALL
ACCUMULATIONS ON THE CAPROCK THIS EVENING AND ALREADY HAZARDOUS
DRIVING CONDITIONS FROM BLACK ICE AND SNOW ON AREA ROADWAYS...HAVE
OPTED TO EXTEND THE WINTER WEATHER ADVISORY ON THE CAPROCK UNTIL
12Z. TOMORROW WILL BE A BITTERLY COLD DAY ACROSS THE AREA...AS HIGHS
WILL GENERALLY REMAIN WELL BELOW FREEZING IN THE 20S DUE TO VERY LOW
THICKNESS VALUES AND A CONTINUED NORTHERLY WIND.
LONG TERM...
AMPLIFIED PATTERN THROUGHOUT THE CONUS WILL SLOWLY RELAX BY MIDWEEK
RESULTING IN BRIEFLY ZONAL FLOW AND SLIGHTLY MILDER TEMPS ON THE
SOUTH PLAINS. THIS PATTERN HOWEVER STILL LOOKS TO BREAK DOWN ON
FRIDAY YIELDING BROADLY CYCLONIC FLOW COURTESY OF A DEEP POLAR
VORTEX TAKING RESIDENCE IN THE HUDSON BAY. JUST A GLANCING BLOW
FROM THIS BROAD TROUGH WILL YIELD A DRY POLAR FRONT LATE THU
NIGHT/EARLY FRI SERVING TO KNOCK HIGHS ON FRI 15-20 DEG BELOW CLIMO.
MEDIUM RANGE MODELS INSIST ON DEEPER WEST OR SWLY FLOW BY THE
WEEKEND INDICATIVE OF MORE SEASONABLE TEMPS.
GREATEST FORECAST CHALLENGE THIS PERIOD INVOLVES LO TEMPS TUE NIGHT
AS STRATUS CLEARS AND WINDS SLACKEN WITHIN AN ELONGATED SURFACE
RIDGE. CHOSE NOT TO LOWER INHERITED MIN TEMPS MUCH BELOW GUIDANCE
FOR NOW AS ALL NUMERICAL DATA INDICATE LIGHT WESTERLY FLOW
OVERNIGHT. SHOULD THESE LIGHT WINDS VEER MORE NLY IN LATER
FORECASTS...THEN THE RECORD DAILY LOW AT LBB /8 SET IN 2005/ MAY
BE IN JEOPARDY.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 8 21 7 40 17 / 60 10 0 0 0
TULIA 12 22 11 41 18 / 50 10 0 0 0
PLAINVIEW 13 23 10 40 18 / 50 10 0 0 0
LEVELLAND 13 22 9 40 19 / 50 10 0 0 0
LUBBOCK 15 25 11 40 19 / 40 10 0 0 0
DENVER CITY 14 26 16 40 20 / 50 10 0 0 0
BROWNFIELD 14 26 13 40 20 / 50 10 0 0 0
CHILDRESS 20 30 17 42 21 / 20 10 0 0 0
SPUR 20 30 15 44 20 / 30 10 0 0 0
ASPERMONT 21 33 20 45 22 / 20 10 10 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM CST TUESDAY FOR THE FOLLOWING
ZONES: TXZ021>024-027>030-033>036-039>042.
WIND CHILL ADVISORY UNTIL 9 AM CST TUESDAY FOR THE FOLLOWING
ZONES: TXZ021>023-027-028.
&&
$$
99/99/99
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
541 PM CST WED DEC 7 2011
.SHORT TERM...THROUGH SATURDAY
254 PM CST WED DEC 7 2011
A QUIET PERIOD OF BELOW NORMAL TEMPERATURES THROUGH
FRIDAY...THE COLDEST AIR OF THE SEASON THUS FAR. THE FORECAST WAS
ON TRACK WITH ONLY MINOR CHANGES MADE.
CURRENTLY MONITORING THE NORTHEAST TO SOUTHWEST ORIENTED LOWER
CLOUDS /2 KFT/ MOVING THROUGH IN WARM ADVECTION IN THE LOWER
LEVELS. COLD FRONT AT THE SURFACE IS REALLY NOT DETECTABLE WITH
FULL SUN IN MN MESSING WITH TEMPERATURES. FRONT IS REALLY NOT
THAT STRONG NEAR THE SURFACE. THE CLOUDS ARE MAKING STEADY
PROGRESS THROUGH NORTH CENTRAL WI BUT HAVE SLOWED OVER SERN
MN...BUT ARE SLOWLY SHIFTING SOUTHEAST. MID-CLOUDS EXTEND FROM
THE DAKOTAS INTO SRN MN AND IOWA AS WELL...BUT THOSE ARE A BIT
THINNER. OTHERWISE...LARGE AREA OF CLEARING IS EVIDENT OVER MOST
OF MN AND THIS SHOULD WORK INTO THE AREA NORTH OF THE MID-CLOUDS
OVERNIGHT. LOW-LEVEL TEMPERATURE WAVE MOVING THROUGH WITH GOOD
WARM ADVECTION SHIFTING EAST /KMPX WARMED 7C OVERNIGHT AT 850MB/
AND NOW COLD ADVECTION BEGINNING. KINL WAS -12C THIS MORNING AT
850MB AND THE PAS /N OF LAKE WINNIPEG/ WAS -19C WITH NORTHWEST
WINDS AT 40 KTS. THIS IS THE COLD POOL SURGING IN THROUGH FRIDAY.
WITH LITTLE WEATHER...THE CONSENSUS OF THE MODELS IS REALLY CLOSE
ON THE OUTCOMES AND FORECAST USED A NAM/GFS/ECMWF/GEM BLEND.
COLD AIR ADVECTION IN NORTHWEST FLOW BEGINS THIS EVENING AREA-WIDE
AND WILL CONTINUE THROUGH FRIDAY. SECOND COLD SURGE COMES IN
THURSDAY EVENING PULLING OUR 925 MB TEMPERATURES DOWN TO -12C
/CURRENTLY ABOUT -4C/. WITH ABOUT 7-10 MPH WINDS FRIDAY
MORNING...BUS STOPS WILL BE COLD WITH WIND CHILLS -15 TO -20F OVER
SERN MN AND IN NORTH CENTRAL WI. DO NOT SEE THIS BECOMING AN
ADVISORY EVENT FOR WIND CHILL.
WARM ADVECTION THEN BEGINS LATE FRIDAY NIGHT AS MAJOR RIDGE
BUILDING OCCURS IN THE CENTRAL U.S. HOWEVER...HAVE LOWERED THE
CENTRAL WISCONSIN LOW TEMPERATURES BASED ON MOSTLY CLEAR SKIES AND
THE RIDGE AXIS PASSING OVERHEAD PER CONSENSUS OF MODELS. THIS USUALLY
DECOUPLES THE BOUNDARY LAYER IN WI...ESPECIALLY CENTRAL...IN THE
FAVORED COLD SPOTS. ALSO HAVE CONTINUED THE TREND OF WARMING THE
TEMPERATURES AFTER MIDNIGHT IN THE WESTERN AREAS AS THE SOUTHERLY
WINDS KICK IN.
HAVE NOT CHANGED MUCH FOR THE HIGHS ON SATURDAY...STILL IN THE
UPPER 20S. BUT THE PRESSURE GRADIENT SUGGESTS WINDS NEEDED TO BE
INCREASED INTO THE 15-25 MPH RANGE WHICH KEEPS THE WIND CHILLS IN
THE LOWER TEENS. SO...UNLIKELY PEOPLE WILL THINK THIS IS A WARMER
DAY THAN FRIDAY EVEN THOUGH HIGH TEMPERATURES RISE 12-15F.
.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
254 PM CST WED DEC 7 2011
THE 07.00Z AND 07.12Z ECMWF...GEM...AND GFS ARE IN GOOD AGREEMENT
THROUGH MONDAY BUT THEN DIVERGE ON HOW THE DETAILS OF THE LARGE
SCALE PATTERN WILL EMERGE. THE WARM ADVECTION CONTINUES THROUGH
SUNDAY WITH PEOPLE FINALLY GETTING SOME OF THAT WARM FEELING.
THERE IS GOOD CONSENSUS IN THE MODELS ON THE NEXT SHORTWAVE
SHIFTING THROUGH WITH A DRIZZLE/SHOWERY/LIGHT PRECIPITATION EVENT MONDAY
AND MONDAY NIGHT. WITH SOME COLD ADVECTION SUGGESTED...POSSIBLY
JUST FROM THE PRECIPITATION COOLING PROCESS...SOME AREAS MAY BE
NEAR FREEZING WITH SUPERCOOLED LIQUID AN ISSUE. WILL HAVE TO
MONITOR THE EVOLUTION OF THIS SYSTEM FOR POSSIBLE FREEZING
DRIZZLE.
TOWARD MIDWEEK THE 07.06Z AND 07.12Z GFS HAVE PROVIDED AN OUTLIER
AGAINST THEIR LIKE ECMWF AND GEM RUNS. THE ECMWF HAS A NEGATIVELY
TILTED STRONG...WARM WEATHER SYSTEM SHIFTING OUT OF THE SWRN LARGE
SCALE TROUGH THROUGH THE AREA WEDNESDAY. THIS WOULD BE A RAIN
SYSTEM WITH 40S AREA-WIDE PER ECMWF SOLUTION. THE GFS HOLDS MORE
ENERGY IN THE NORTHERN STREAM WITH A COLDER/SLOWER SOLUTION. IT
SEEMS TO BE THE OUTLIER. IN ANY CASE...RIGHT NOW WE ARE RAMPING UP
THE WEATHER FOR THAT PERIOD AND HAVE KEPT A S/RS/S MIX OF
PRECIPITATION. WOULD THINK THE TREND WILL BE WARMER WITH FUTURE
FORECASTS FOR MID-WEEK.
&&
.AVIATION...TONIGHT AND THURSDAY
541 PM CST WED DEC 7 2011
A BAND OF MVFR CLOUDS OVER BOTH TAF SITES SHOULD MOVE EAST OF THE
REGION THIS EVENING. THE 07.21Z RUC SEEMS TO HAVE A GOOD HANDLE ON
THIS MOISTURE FIELD AROUND 925 MB AND MOVES IT OUT OF KRST RIGHT
AROUND 00Z AND OUT OF KLSE AROUND 02Z AND HAVE USED THIS AS
TIMING. AFTER THAT...IT LOOKS AS IF SOME MID TO HIGH LEVEL CLOUDS
WILL MOVE IN AND OUT OF THE REGION THROUGH THE REMAINDER OF THE
NIGHT INTO THURSDAY MORNING. COULD EVEN SEE SOME OCCASIONAL
CEILINGS FROM THESE CLOUDS BUT IF THAT DOES OCCUR...THEY WILL BE
HIGH VFR CEILINGS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
254 PM CST WED DEC 7 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...04
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
219 PM CST TUE DEC 6 2011
.SYNOPSIS...SEASONABLY COLD AND VERY QUIET FOR THE EARLY PART OF
DECEMBER.
AMPLIFIED LNGWV PATTERN IN PLACE...WITH LARGE SCALE FLOW
DOMINATED BY MASSIVE RIDGE OVER THE ERN PAC. THE FLOW DOWNSTREAM
WAS SOMEWHAT SPLIT...WITH NRN STREAM MUCH STRONGER THAN THE
SRN...AND WITH TROFFING OVER ERN NOAM. THE TREND DURING THE FIRST
PART OF THE FCST PERIOD WL BE FOR BROAD ERN NOAM TROF TO EXPAND
SWD FM VORTEX IN THE HUDSON BAY RGN. THE SAME FEATURES SHOULD
REMAIN IN PLACE FOR THE LATTER HALF OF THE PERIOD...BUT WITH A
GRADUAL DECR IN AMPLITUDE.
TEMPS ACRS THE AREA HAVE COOLED TO NR NORMAL...AND WL CONT THE
DOWNSLIDE TO SOMEWHAT BLO NORMAL LEVELS AS THE UPR TROF DEEPENS
OVER THE RGN. ALTHOUGH THE N NOW HAS A DECENT SNOWCOVER...THE LACK
OF A WIDESPREAD DEEP SNOWCOVER ACRS THE ENTIRE REGION WL PREVENT
THIS FROM TURNING INTO A VERY COLD PERIOD. READINGS SHOULD REBOUND
DURING THE LATTER PART OF THE PERIOD AS UPR FLOW BECOMES MORE WLY.
GULF MOISTURE WL REMAIN TRAPPED WELL S OF THE AREA...AND DON/T SEE
ANY STG SYSTEMS IN THE FAST NWLY/WNWLY FLOW EITHER. EVEN THE
PROSPECT FOR LAKE-EFFECT LOOKS LOW AS FLOW WL BE RATHER WLY. SO
DON/T EXPECT MUCH PCPN DURING THE PERIOD.
&&
.SHORT TERM...TONIGHT AND WEDNESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH
PRESSURE STRETCHING FROM THE CENTRAL GREAT PLAINS...ACROSS THE
GREAT LAKES...AND INTO QUEBEC THIS AFTERNOON. DESPITE THE SURFACE
HIGH...LOW CLOUDS OVER WESTERN AND CENTRAL WISCONSIN ARE
STUBBORNLY MOVING TO THE NORTHEAST. EARLIER FLURRY ACTIVITY OVER
THE DOOR PENINSULA IS ALSO FINALLY STARTING TO MOVE TO THE EAST AS
WELL. MEANWHILE...OVER THE LAKE WINNIPEG REGION...A DIVING
SHORTWAVE IS SENDING A WARM FRONT TO THE SOUTHEAST. AS THE SURFACE
HIGH DRIFTS TO THE SOUTH TONIGHT...CLOUDS AND TEMPS REMAIN THE
MAIN FORECAST CONCERNS.
TONIGHT...SURFACE HIGH PRESSURE WILL DRIFT TO THE SOUTH AS HEIGHT
FALLS OCCUR OVER SOUTH-CENTRAL CANADA AND THE FAR NORTHERN PLAINS.
LOW LEVEL SW WINDS WILL STRENGTHEN AND CONTINUE TO PUSH THE LOW
STRATUS TO THE NE. BASED ON THE LATEST SATELLITE OBS...TEND TO
THINK THE LOW STRATUS WILL STAY IN TACT OVER CENTRAL INTO EAST-
CENTRAL WISCONSIN THROUGH MID-EVENING WHILE NORTH- CENTRAL
WISCONSIN MAY ACTUALLY TURN PARTLY CLOUDY. UNLESS SOME HOLES
DEVELOP LATER THIS AFTERNOON...WILL TREND THE FORECAST THIS
DIRECTION. DRIER AIR IS THEN PROGGED TO PUSH THE STUBBORN STRATUS
TO THE EAST LATE THIS EVENING AND OVERNIGHT. SOME HIGH CLOUDS MAY
ARRIVE LATE AHEAD OF A SHEAR SHORTWAVE DIVING OVER SOUTH-CENTRAL
CANADA. THE STRENGTHENING WIND FIELD AND CLOUD COVER WILL KEEP
TEMPS WARMER THAN LAST NIGHT...AND WILL GO UPPER SINGLE DIGITS
NORTH TO LOWER 20S SE.
WEDNESDAY...THE SHEARED WAVE WILL SLIDE SOUTHEAST OVER LAKE
SUPERIOR...AND PUSH A WEAKENING COLD FRONT ACROSS THE FORECAST
AREA DURING THE MORNING. WILL SEE SOME SCT TO BKN MID CLOUDS WITH
THE FRONT...BUT NO REAL THREAT OF SNOW SHOWERS EXCEPT OVER
NORTHERN VILAS WHERE WNW WINDS MAY SEND A SCT SNOW SHOWERS ALONG
THE U.P.-WISCONSIN BORDER. TEMPS A COUPLE DEGREES WARMER THAN
TODAY OFF OF A WARMER START IN THE MORNING.
.LONG TERM...WED NGT THROUGH NEXT TUE. TRENDED TEMPS DOWN A
LITTLE BOTH THU AND FRI AS FCST AREA WL BE DOMINATED BY COLD AIR
FLOWING SEWD FM CANADA. WLY FLOW SHOULD KEEP SIG LAKE-EFFECT NE OF
THE AREA. THE CANADIAN GLOBAL MODEL BROUGHT SOME PCPN ACRS E-C WI
ON THU NGT INTO FRI AS BAROCLINIC LEAF TYPE FEATURES SLIDES ACRS
THE AREA. THE FEATURE WAS ALSO AT LEAST HINTED AT ON THE REST OF
THE MODELS...BUT THEY WERE ALL WEAKER AND FARTHER S. SO CANADIAN
SEEMS LIKE AN OUTLIER AND WL STICK WITH DRY FCST.
&&
.AVIATION...LOW CLOUDS ARE HANGING TOUGH LATE THIS MORNING OVER
WESTERN AND CENTRAL WISCONSIN...THOUGH THERE MAY BE A SLIGHT
DIMINISHING TREND OF THE FLURRY ACTIVITY. LOW LEVEL WINDS WILL TURN
TO THE SOUTHWEST THIS AFTERNOON...WHICH WILL TEND TO PUSH THE LOW
CLOUDS TO THE EAST. AS A RESULT...HAVE MAINTAINED THE LOW END VFR
BKN CONDITIONS OVER CENTRAL AND NORTH-CENTRAL TAF SITES THROUGH LATE
THIS AFTERNOON AND EARLY THIS EVENING. SOME EROSION IS LIKELY THIS
AFTERNOON...BUT QUITE DIFFICULT TO DETERMINE WHERE IT WILL OCCUR.
LOW LEVEL DRY AIR WILL FINALLY SURGE INTO THE AREA THIS EVENING
WHICH WILL CLEAR SKIES OUT. MID AND HIGH CLOUDS WILL ARRIVE LATE
TONIGHT AHEAD OF THE UPPER LEVEL WAVE. THOUGH DO NOT SEE LOW CLOUDS
REDEVELOPING...STRENGTHENING SW FLOW WILL LEAD TO LLWS DEVELOPING
09-15Z TOMORROW.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MPC/SKOWRONSKI
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
146 PM CST TUE DEC 6 2011
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE.
.SHORT TERM...TODAY THROUGH WEDNESDAY.
FORECAST CONCERNS THIS PERIOD...CLOUDS
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
STRETCHING FROM WESTERN LAKE SUPERIOR INTO WESTERN IA. LOWER CLOUD
CLEARING OVER MUCH OF EASTERN WI AS DRIER AIR...SEEN ON GRB
SOUNDING...WORKING IN. CLOUDS HANGING TOUGH OVER WESTERN PART OF
STATE. SURFACE HIGH WILL CONTINUE TO SHIFT OVER STATE
TODAY...EXITING TONIGHT WITH COLD FRONT ASSOCIATED WITH LOW MOVING
THROUGH NORTHERN CANADA MOVING THROUGH STATE ON WED.
QUESTION IS WHAT WILL HAPPEN WITH CLOUDS TODAY. AREA OF
CONVERGENCE ASSOCIATED WITH WEAK SURFACE TROF OVER WESTERN WI TO
WEAKEN THIS MORNING. SOME MODELS SHOW LOWER CLOUD MOVING BACK INTO
EASTERN WI LATE TODAY AS LOW LEVEL WINDS SHIFT TO THE SOUTHWEST LATE.
SOME SHOW CLOUD DISSIPATING THROUGH THE DAY AS SUPPORT WEAKENS.
HAVE LEANED TOWARDS CANADIAN THAT SHOWS CURRENT CLEARING OVER
EASTERN AND NORTH CENTRAL WI...THOUGH WILL STAY WITH PARTLY
CLOUDY/PARTLY SUNNY WORDING GIVEN CIRRUS MOVING THROUGH AND SOME
UNCERTAINTY. CLOUDS CONTINUE TO MOVE SOUTH OFF LAKE
SUPERIOR/MICHIGAN IN THE FAR EAST. THUS CLEARING SLOWED A BIT FROM
PREVIOUS FORECAST...THOUGH LITTLE CHANGE MADE IN TEMPERATURE
FORECAST.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY.
MODELS HAD AN UPPER TROUGH OVER MUCH OF THE CONUS EARLY IN THE
PERIOD...WITH THE FLOW BECOMING ZONAL OVER THE UPPER GREAT LAKES BY
EARLY NEXT WEEK.
AN ARCTIC FRONT WILL BRING MUCH COLDER AIR INTO THE FORECAST AREA
ON THURSDAY. HAVE A SLIGHT CHANCE OF SNOW SHOWERS IN VILAS COUNTY
FOR THE END OF THE WORK WEEK. LAPSE RATES OVER LAKE SUPERIOR
SHOULD BE STEEP...BUT WINDS APPEARED TO HAVE TOO MUCH OF A
WESTERLY COMPONENT TO GO AS HIGH AS CHANCE POPS. NEAR OR ABOVE
NORMAL TEMPERATURES CAN BE EXPECTED BY SUNDAY AS A SURFACE RIDGE
PASSES EAST OF THE AREA AND SOUTHWEST WINDS BRING WARMER AIR INTO
THE STATE.
HAVE SOME SLIGHT CHANCE POPS LATE IN THE PERIOD WITH SHORT WAVE
ENERGY AND A SURFACE LOW APPROACHING WISCONSIN. MAY NEED TO GO
WITH HIGHER POPS IN THE AFTERNOON FORECAST PACKAGE OR TOMORROW
MORNING IF CONDITIONS APPEAR MORE FAVORABLE FOR PRECIPITATION.
&&
.AVIATION...LOW CLOUDS ARE HANGING TOUGH LATE THIS MORNING OVER
WESTERN AND CENTRAL WISCONSIN...THOUGH THERE MAY BE A SLIGHT
DIMINISHING TREND OF THE FLURRY ACTIVITY. LOW LEVEL WINDS WILL TURN
TO THE SOUTHWEST THIS AFTERNOON...WHICH WILL TEND TO PUSH THE LOW
CLOUDS TO THE EAST. AS A RESULT...HAVE MAINTAINED THE LOW END VFR
BKN CONDITIONS OVER CENTRAL AND NORTH-CENTRAL TAF SITES THROUGH LATE
THIS AFTERNOON AND EARLY THIS EVENING. SOME EROSION IS LIKELY THIS
AFTERNOON...BUT QUITE DIFFICULT TO DETERMINE WHERE IT WILL OCCUR.
LOW LEVEL DRY AIR WILL FINALLY SURGE INTO THE AREA THIS EVENING
WHICH WILL CLEAR SKIES OUT. MID AND HIGH CLOUDS WILL ARRIVE LATE
TONIGHT AHEAD OF THE UPPER LEVEL WAVE. THOUGH DO NOT SEE LOW CLOUDS
REDEVELOPING...STRENGTHENING SW FLOW WILL LEAD TO LLWS DEVELOPING
09-15Z TOMORROW.
MPC
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1151 AM CST TUE DEC 6 2011
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
332 AM CST TUE DEC 6 2011
MAIN FORECAST CONCERNS THIS PACKAGE...CLOUDS AND TEMPERATURES THRU
THE PERIOD.
DATA ANALYSIS AT 06Z HAD A RIDGE OF HIGH PRESSURE EXTENDING FROM
NORTH OF LK SUPERIOR ACROSS MN TO NEB AND WESTERN KS. A LARGE AREA
OF LOW PRESSURE WAS LOCATED OVER NORTH-CENTRAL CAN WITH FALLING
PRESSURES IN THE NORTHERN PLAINS. STRATUS CLOUDS REMAINS TRAPPED
ACROSS THE AREA...UNDER AN INVERSION BETWEEN 850-800MB AND EAST OF
THE SFC RIDGE AXIS. WEST EDGE OF THE CLOUDS WAS NEAR A KDLH-KOTG
LINE...MAKING VERY SLOW PROGRESS EAST/SOUTH. WEAK SFC-925MB TROUGH
AND CONVERGENCE...ALONG WITH THE SLOWLY COOLING LOWER LEVELS
CONTINUED TO SQUEEZE SOME FLURRIES/VERY LIGHT SNOW OUT OF THE
COLUMN OVER MUCH OF WESTERN WI INTO EXTREME EASTERN MN.
NO PROBLEMS NOTED WITH 06.00Z MODEL INITIALIZATIONS. SOLUTIONS QUITE
SIMILAR FOR TODAY THRU THU NIGHT...AT LEAST WITH THE SHORTWAVES AND
LARGER SCALE FEATURES. MODELS STILL STRUGGLING WITH THE LOWER LEVEL
MOISTURE/RH FIELDS AND STRATUS CLOUDS ACROSS THE AREA. DPROG/DT OF
500MB HGTS AT 06.00Z SHOWED MODEL RUNS OF 04.00Z AND 05.00Z VERIFIED
QUITE WELL ACROSS NOAM...FAVORING STRONGER OF EARLIER MODELS WITH
THE NORTHERN PORTION OF THE TROUGH AND FASTER OF EARLIER MODELS WITH
THE SOUTHWEST CONUS PORTION OF THE TROUGH. THRU TODAY/TONIGHT MODELS
TREND TOWARD A TIGHTER/FASTER CONSENSUS WITH THE SOUTHERN PORTION OF
THE TROUGH MOVING EAST INTO THE MID/LOWER MS VALLEY AND WEAKENING OF
THE NORTHERN PORTION OF THE TROUGH AS IT MOVES EAST OF THE REGION.
TREND CONTINUES FASTER WITH THE LOWER MS VALLEY TROUGH WED/WED NIGHT
AS IT TO THE EAST COAST BY 12Z THU. BETTER CONSENSUS FOR BROAD
TROUGHING/NORTHWEST FLOW TO DEVELOP OVER THE NORTH-CENTRAL CONUS/
GREAT LAKES REGION. THIS TROUGH DEEPENS OVER THE MID/UPPER MS VALLEY
THU/THU NIGHT...BUT MINOR DIFFERENCES IN THE TIMING/STRENGTH DETAILS
DEVELOP BY 12Z FRI. OVERALL BETTER RUN-TO-RUN CONSISTENCY FOR TODAY
THRU THU NIGHT SHOWN BY ECMWF...ESPECIALLY WITH THE SOUTHERN STREAM
ENERGY EARLY IN THE PERIOD. CHECK OF OBS VS. MODEL DATA AT 06Z
SHOWED MODELS ALL QUITE GOOD WITH THE CENTRAL CONUS SFC MASS
FIELDS...THOUGH AGAIN CONTINUED TO STRUGGLE WITH THE LOWER LEVEL RH
AND STRATUS DECKS TRAPPED ACROSS THE REGION. ECMWF/ RUC LOOK TO BE
DOING BEST WITH THE 925MB RH/STATUS CLOUDS OVER MN/ WI/IA WHILE ONLY
MODEL SOME INDICATION OF THE FLURRIES WAS THE GFS. THUS NO CLEAR
DETERMINISTIC MODEL FAVORITE. WITH MODELS TRENDING TOWARD A TIGHTER
CONSENSUS MUCH OF THE PERIOD...FAVORED THE CONSENSUS. SHORT TERM
FCST CONFIDENCE AVERAGE TO GOOD THIS CYCLE.
IN THE SHORT TERM...LOW CLOUDS/CLEARING REMAIN PROBLEMATIC TODAY/
TONIGHT WITH TYPICAL POOR MODEL PERFORMANCE ON THIS AND THE TIME OF
YEAR WHEN LOW CLOUDS LIKE TO HANG TOUGH. MODEL CONSENSUS KEEPS 70+
PERCENT 925MB RH OVER THE CENTRAL/EAST PARTS OF THE FCST AREA THRU
THE DAY WITH ONLY SLOW EROSION/ADVECTION ON THE WESTERN SIDE.
RAISED CLOUD COVER IN SKY GRIDS TO REFLECT A SLOWER/NON CLEARING
TODAY. MOVED THE CLEARING INTO TONIGHT WITH INCREASING WEST SFC-
850MB FLOW NORTH OF THE LOW LEVEL RIDGE AXIS TO FINALLY ADVECT THE
MOISTURE EAST AND OUT OF THE AREA. SFC-925MB TROUGH WEAKENS THRU
THIS MORNING...BUT GIVEN SLOW MOVEMENT OF THE LOW LEVEL FEATURES...
LINGERED SCT FLURRIES OVER THE NORTH HALF OF THE FCST AREA WHERE
RADAR REFLECTIVITY/SFC OBS CONTINUED TO DETECT/REPORT FLURRIES AS OF
09Z. REST OF SHORT-TERM PERIOD GENERALLY COOL/QUIET. SHORTWAVE
ENERGY PASSES NORTH OF THE FCST AREA WED/WED NIGHT WITH BULK OF
FORCING/LIFT AND 850-500MB MOISTURE/SATURATION REMAINING NORTH OF
THE FCST AREA. COLD/DRY AIRMASS SETTLES ACROSS THE AREA IN THE WAKE
OF THIS SHORTWAVE TROUGH FOR THU/THU NIGHT. THIS AS MORE SHORTWAVE
ENERGY DROPS SOUTHEAST ACROSS THE NORTHERN PLAINS FOR THU/THU NIGHT.
BULK OF THE LOWER LEVEL THERMO-DYNAMIC FORCING AND INCREASE OF
MOISTURE IN THE 925-700MB LAYER REMAINS SOUTH OF THE FCST AREA
THU/THU NIGHT. ONLY LINGERED A SMALL -SN CHANCE ACROSS THE EXTREME
SOUTH END OF THE FCST AREA THU NIGHT TO BLEND WITH NEIGHBORING
GRIDS. SATURATION OF THE COLUMN OVER THE NORTH END OF THE FCST AREA
THU/THU NIGHT...NORTH OF THE SHORTWAVE TRACK...AN ISSUE IN THE
COLDER COLUMN THERE. MAY YET SEE SCT FLURRIES ALONG/NORTH OF HWY 29
THU/THU NIGHT BUT LEFT THIS DRY FOR NOW. GENERALLY CARRIED PARTLY
CLOUDY TO MOSTLY CLEAR SKIES FOR WED THRU THU NIGHT.
HIGH/LOW TEMPERATURES PROBLEMATIC WITH SNOW COVERING THE NORTHWEST
HALF OF THE FCST AREA WHILE THE SOUTHEAST HALF IS SNOW-FREE. WITH
MORE CLOUDS/OVERCAST TODAY...TRENDED HIGHS FOR MINIMAL DIURNAL
SWING AND AT OR BELOW NUMERICAL GUIDANCE. WITH PARTLY CLOUDY SKIES
TONIGHT BUT SOME SOUTHWEST GRADIENT WINDS...FAVORED A BLEND OF THE
GUIDANCE LOWS. SOUTHWEST/WEST WINDS AHEAD OF THE NEXT COLD FRONT AND
SOME SUNSHINE WED...TRENDED TOWARD WARMER OF GUIDANCE HIGHS...
ESPECIALLY OVER THE SNOW-FREE SOUTHEAST HALF OF THE FCST AREA.
APPEARS BOUNDARY LAYER WINDS WILL KEEP LOW LEVELS STIRRED WED
NIGHT AND TRENDED TOWARD WARMER OF GUIDANCE LOWS. FAVORED A MODEL
CONSENSUS OF HIGHS FOR THU...WHICH BLENDS WELL WITH NEIGHBORING
GRIDS BUT MAY BE TOO WARM WITH MDT/STRONG LOW LEVEL COLD ADVECTION
OVER THE REGION BY MID-DAY. FAVORED THE MODEL CONSENSUS FOR LOWS THU
NIGHT...WHICH ALSO MAY BE TOO WARM IF WINDS ARE LIGHTER THAN
EXPECTED ESPECIALLY OVER THE SNOW-COVERED PORTIONS OF THE FCST AREA.
.LONG TERM...FRIDAY THROUGH MONDAY
332 AM CST TUE DEC 6 2011
LONG-TERM FCST CONFIDENCE AVERAGE. 06.00Z MEDIUM RANGE MODELS IN
REASONABLE AGREEMENT WITH EACH OTHER AND THEIR PREVIOUS RUNS FRI
THRU SUNDAY WITH THE LONGWAVE TROUGH BEING PROGRESSIVE AND HGTS
RISING OVER THE UPPER MIDWEST FRIDAY INTO SUNDAY. COLD SFC HIGH
PRESSURE DRIFTS OVER THE AREA FRI THEN MOVES SOUTH OF THE AREA FOR
SAT/SUN. STRONG LOW LEVEL WARM ADVECTION SPREADS ACROSS THE AREA SAT
INTO SAT NIGHT WITH 925MB TEMPS IN THE 0 TO +4C RANGE BY 12Z SUN.
BELOW/MUCH BELOW NORMAL TEMPS FRI LOOK TO WARM TO ABOVE/MUCH ABOVE
NORMAL BY SUN AS BULK OF THE WARM ADVECTION GOES INTO WARMING UNDER
PARTLY CLOUDY/MOSTLY SUNNY SKIES. RAISED HIGHS A BIT OVER THE
SOUTHEAST HALF OF THE FCST AREA SUN WITH THE LACK OF SNOW COVER.
GFS/ECMWF SOLUTIONS DIVERGE FOR MON. ECMWF SLIDES A COLD FRONT AND
WEAK LOW LEVEL COLD ADVECTION ACROSS THE AREA WHILE GFS TRACKS A LOW
INTO NORTHWEST MN KEEPING THE AREA UNDER LOW LEVEL WARM ADVECTION.
EITHER WAY...APPEARS SOME OF THE SNOW COVER WILL MELT SUN AND MON
WILL SEE CONTINUED ABOVE NORMAL TEMPS. BIGGEST LONG-TERM QUESTION
LOOKS TO BE WILL THERE BE ENOUGH LOWER LEVEL MOISTURE FOR A SMALL
PRECIP CHANCE FOR PARTS OF THE AREA BY LATER MON. MODEL CONSENSUS
DATA USED IN THE DAY 4-7 FCST GRIDS LOOKS TO HAVE ALL OF THIS WELL
TRENDED FOR NOW.
&&
.AVIATION...THROUGH 18Z WEDNESDAY
1151 AM CST TUE DEC 6 2011
BIGGEST CHALLENGE THIS TAF PERIOD ARE CEILINGS AND CLEARING TRENDS
AT BOTH TAF SITES. CURRENTLY BAND OF MVFR CEILINGS STRETCHES FROM
NORTHEAST IOWA...SOUTHEAST MINNESOTA...AND WESTERN WISCONSIN.
INCLUDED A SHORT TEMPO GROUP AT KRST FOR SCATTERED FLURRIES AND
SUB-MVFR CONDITIONS UNTIL MAIN RIDGE AXIS PUSHES THROUGH. EXPECTING
CLEARING AND VFR CONDITIONS TO EDGE CLOSER TO KRST BY 02Z AND TO
KLSE BY 05Z. WESTERN EDGE OF CLOUD COVER SEEMS TO BE MIXING BETTER
THIS AFTERNOON...AND CLEARING TREND MAY BE FASTER IF THIS CONTINUES.
VFR CONDITIONS WILL PERSIST OVERNIGHT AS WINDS SHIFT TO
SOUTHWEST...AHEAD OF A COLD FRONT PROGGED TO MOVE THROUGH THE
REGION. FRONTAL PASSAGE EXPECTED AT KRST AT 12Z WED AND AT KLSE AT
15Z. BROKEN MID TO HIGH LEVEL CLOUDS CURRENTLY OVER NORTH DAKOTA
WILL MOVE IN THE WAKE OF FRONTAL PASSAGE AND WINDS AHEAD AND
BEHIND THE FRONT WILL INCREASE TO 10-15 KT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
332 AM CST TUE DEC 6 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM... RRS
LONG TERM.... RRS
AVIATION...ZT/MW
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
607 AM CST TUE DEC 6 2011
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
.SHORT TERM...TODAY THROUGH WEDNESDAY.
FORECAST CONCERNS THIS PERIOD...CLOUDS
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
STRETCHING FROM WESTERN LAKE SUPERIOR INTO WESTERN IA. LOWER CLOUD
CLEARING OVER MUCH OF EASTERN WI AS DRIER AIR...SEEN ON GRB
SOUNDING...WORKING IN. CLOUDS HANGING TOUGH OVER WESTERN PART OF
STATE. SURFACE HIGH WILL CONTINUE TO SHIFT OVER STATE
TODAY...EXITING TONIGHT WITH COLD FRONT ASSOCIATED WITH LOW MOVING
THROUGH NORTHERN CANADA MOVING THROUGH STATE ON WED.
QUESTION IS WHAT WILL HAPPEN WITH CLOUDS TODAY. AREA OF
CONVERGENCE ASSOCIATED WITH WEAK SURFACE TROF OVER WESTERN WI TO
WEAKEN THIS MORNING. SOME MODELS SHOW LOWER CLOUD MOVING BACK INTO
EASTERN WI LATE TODAY AS LOW LEVEL WINDS SHIFT TO THE SOUTHWEST LATE.
SOME SHOW CLOUD DISSIPATING THROUGH THE DAY AS SUPPORT WEAKENS.
HAVE LEANED TOWARDS CANADIAN THAT SHOWS CURRENT CLEARING OVER
EASTERN AND NORTH CENTRAL WI...THOUGH WILL STAY WITH PARTLY
CLOUDY/PARTLY SUNNY WORDING GIVEN CIRRUS MOVING THROUGH AND SOME
UNCERTAINTY. CLOUDS CONTINUE TO MOVE SOUTH OFF LAKE
SUPERIOR/MICHIGAN IN THE FAR EAST. THUS CLEARING SLOWED A BIT FROM
PREVIOUS FORECAST...THOUGH LITTLE CHANGE MADE IN TEMPERATURE
FORECAST.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY.
MODELS HAD AN UPPER TROUGH OVER MUCH OF THE CONUS EARLY IN THE
PERIOD...WITH THE FLOW BECOMING ZONAL OVER THE UPPER GREAT LAKES BY
EARLY NEXT WEEK.
AN ARCTIC FRONT WILL BRING MUCH COLDER AIR INTO THE FORECAST AREA
ON THURSDAY. HAVE A SLIGHT CHANCE OF SNOW SHOWERS IN VILAS COUNTY
FOR THE END OF THE WORK WEEK. LAPSE RATES OVER LAKE SUPERIOR
SHOULD BE STEEP...BUT WINDS APPEARED TO HAVE TOO MUCH OF A
WESTERLY COMPONENT TO GO AS HIGH AS CHANCE POPS. NEAR OR ABOVE
NORMAL TEMPERATURES CAN BE EXPECTED BY SUNDAY AS A SURFACE RIDGE
PASSES EAST OF THE AREA AND SOUTHWEST WINDS BRING WARMER AIR INTO
THE STATE.
HAVE SOME SLIGHT CHANCE POPS LATE IN THE PERIOD WITH SHORT WAVE
ENERGY AND A SURFACE LOW APPROACHING WISCONSIN. MAY NEED TO GO
WITH HIGHER POPS IN THE AFTERNOON FORECAST PACKAGE OR TOMORROW
MORNING IF CONDITIONS APPEAR MORE FAVORABLE FOR PRECIPITATION.
&&
.AVIATION...DRIER AIR WORKING IN OVER EASTERN WI HAS CLEARED SKIES
FOR MUCH OF EASTERN WI AND NORTH CENTRAL WI...NOW WORKING INTO
CENTRAL WI. SUPPORT FOR FLURRIES/CLOUDS JUST WEST OF CWA/AUW TO
DIMINISH THIS MORNING. THOUGHTS ARE CLOUDS WILL CONTINUE TO DIMINISH
OVER WEST. INCREASING SOUTHWEST WINDS THIS EVENING...30 KTS AT 2K
FT. THOUGH NOT STRONG ENOUGH DIFFERENCE FROM SURFACE FOR LLWS AT
THIS TIME.
TE
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
537 AM CST TUE DEC 6 2011
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
332 AM CST TUE DEC 6 2011
MAIN FORECAST CONCERNS THIS PACKAGE...CLOUDS AND TEMPERATURES THRU
THE PERIOD.
DATA ANALYSIS AT 06Z HAD A RIDGE OF HIGH PRESSURE EXTENDING FROM
NORTH OF LK SUPERIOR ACROSS MN TO NEB AND WESTERN KS. A LARGE AREA
OF LOW PRESSURE WAS LOCATED OVER NORTH-CENTRAL CAN WITH FALLING
PRESSURES IN THE NORTHERN PLAINS. STRATUS CLOUDS REMAINS TRAPPED
ACROSS THE AREA...UNDER AN INVERSION BETWEEN 850-800MB AND EAST OF
THE SFC RIDGE AXIS. WEST EDGE OF THE CLOUDS WAS NEAR A KDLH-KOTG
LINE...MAKING VERY SLOW PROGRESS EAST/SOUTH. WEAK SFC-925MB TROUGH
AND CONVERGENCE...ALONG WITH THE SLOWLY COOLING LOWER LEVELS
CONTINUED TO SQUEEZE SOME FLURRIES/VERY LIGHT SNOW OUT OF THE
COLUMN OVER MUCH OF WESTERN WI INTO EXTREME EASTERN MN.
NO PROBLEMS NOTED WITH 06.00Z MODEL INITIALIZATIONS. SOLUTIONS QUITE
SIMILAR FOR TODAY THRU THU NIGHT...AT LEAST WITH THE SHORTWAVES AND
LARGER SCALE FEATURES. MODELS STILL STRUGGLING WITH THE LOWER LEVEL
MOISTURE/RH FIELDS AND STRATUS CLOUDS ACROSS THE AREA. DPROG/DT OF
500MB HGTS AT 06.00Z SHOWED MODEL RUNS OF 04.00Z AND 05.00Z VERIFIED
QUITE WELL ACROSS NOAM...FAVORING STRONGER OF EARLIER MODELS WITH
THE NORTHERN PORTION OF THE TROUGH AND FASTER OF EARLIER MODELS WITH
THE SOUTHWEST CONUS PORTION OF THE TROUGH. THRU TODAY/TONIGHT MODELS
TREND TOWARD A TIGHTER/FASTER CONSENSUS WITH THE SOUTHERN PORTION OF
THE TROUGH MOVING EAST INTO THE MID/LOWER MS VALLEY AND WEAKENING OF
THE NORTHERN PORTION OF THE TROUGH AS IT MOVES EAST OF THE REGION.
TREND CONTINUES FASTER WITH THE LOWER MS VALLEY TROUGH WED/WED NIGHT
AS IT TO THE EAST COAST BY 12Z THU. BETTER CONSENSUS FOR BROAD
TROUGHING/NORTHWEST FLOW TO DEVELOP OVER THE NORTH-CENTRAL CONUS/
GREAT LAKES REGION. THIS TROUGH DEEPENS OVER THE MID/UPPER MS VALLEY
THU/THU NIGHT...BUT MINOR DIFFERENCES IN THE TIMING/STRENGTH DETAILS
DEVELOP BY 12Z FRI. OVERALL BETTER RUN-TO-RUN CONSISTENCY FOR TODAY
THRU THU NIGHT SHOWN BY ECMWF...ESPECIALLY WITH THE SOUTHERN STREAM
ENERGY EARLY IN THE PERIOD. CHECK OF OBS VS. MODEL DATA AT 06Z
SHOWED MODELS ALL QUITE GOOD WITH THE CENTRAL CONUS SFC MASS
FIELDS...THOUGH AGAIN CONTINUED TO STRUGGLE WITH THE LOWER LEVEL RH
AND STRATUS DECKS TRAPPED ACROSS THE REGION. ECMWF/ RUC LOOK TO BE
DOING BEST WITH THE 925MB RH/STATUS CLOUDS OVER MN/ WI/IA WHILE ONLY
MODEL SOME INDICATION OF THE FLURRIES WAS THE GFS. THUS NO CLEAR
DETERMINISTIC MODEL FAVORITE. WITH MODELS TRENDING TOWARD A TIGHTER
CONSENSUS MUCH OF THE PERIOD...FAVORED THE CONSENSUS. SHORT TERM
FCST CONFIDENCE AVERAGE TO GOOD THIS CYCLE.
IN THE SHORT TERM...LOW CLOUDS/CLEARING REMAIN PROBLEMATIC TODAY/
TONIGHT WITH TYPICAL POOR MODEL PERFORMANCE ON THIS AND THE TIME OF
YEAR WHEN LOW CLOUDS LIKE TO HANG TOUGH. MODEL CONSENSUS KEEPS 70+
PERCENT 925MB RH OVER THE CENTRAL/EAST PARTS OF THE FCST AREA THRU
THE DAY WITH ONLY SLOW EROSION/ADVECTION ON THE WESTERN SIDE.
RAISED CLOUD COVER IN SKY GRIDS TO REFLECT A SLOWER/NON CLEARING
TODAY. MOVED THE CLEARING INTO TONIGHT WITH INCREASING WEST SFC-
850MB FLOW NORTH OF THE LOW LEVEL RIDGE AXIS TO FINALLY ADVECT THE
MOISTURE EAST AND OUT OF THE AREA. SFC-925MB TROUGH WEAKENS THRU
THIS MORNING...BUT GIVEN SLOW MOVEMENT OF THE LOW LEVEL FEATURES...
LINGERED SCT FLURRIES OVER THE NORTH HALF OF THE FCST AREA WHERE
RADAR REFLECTIVITY/SFC OBS CONTINUED TO DETECT/REPORT FLURRIES AS OF
09Z. REST OF SHORT-TERM PERIOD GENERALLY COOL/QUIET. SHORTWAVE
ENERGY PASSES NORTH OF THE FCST AREA WED/WED NIGHT WITH BULK OF
FORCING/LIFT AND 850-500MB MOISTURE/SATURATION REMAINING NORTH OF
THE FCST AREA. COLD/DRY AIRMASS SETTLES ACROSS THE AREA IN THE WAKE
OF THIS SHORTWAVE TROUGH FOR THU/THU NIGHT. THIS AS MORE SHORTWAVE
ENERGY DROPS SOUTHEAST ACROSS THE NORTHERN PLAINS FOR THU/THU NIGHT.
BULK OF THE LOWER LEVEL THERMO-DYNAMIC FORCING AND INCREASE OF
MOISTURE IN THE 925-700MB LAYER REMAINS SOUTH OF THE FCST AREA
THU/THU NIGHT. ONLY LINGERED A SMALL -SN CHANCE ACROSS THE EXTREME
SOUTH END OF THE FCST AREA THU NIGHT TO BLEND WITH NEIGHBORING
GRIDS. SATURATION OF THE COLUMN OVER THE NORTH END OF THE FCST AREA
THU/THU NIGHT...NORTH OF THE SHORTWAVE TRACK...AN ISSUE IN THE
COLDER COLUMN THERE. MAY YET SEE SCT FLURRIES ALONG/NORTH OF HWY 29
THU/THU NIGHT BUT LEFT THIS DRY FOR NOW. GENERALLY CARRIED PARTLY
CLOUDY TO MOSTLY CLEAR SKIES FOR WED THRU THU NIGHT.
HIGH/LOW TEMPERATURES PROBLEMATIC WITH SNOW COVERING THE NORTHWEST
HALF OF THE FCST AREA WHILE THE SOUTHEAST HALF IS SNOW-FREE. WITH
MORE CLOUDS/OVERCAST TODAY...TRENDED HIGHS FOR MINIMAL DIURNAL
SWING AND AT OR BELOW NUMERICAL GUIDANCE. WITH PARTLY CLOUDY SKIES
TONIGHT BUT SOME SOUTHWEST GRADIENT WINDS...FAVORED A BLEND OF THE
GUIDANCE LOWS. SOUTHWEST/WEST WINDS AHEAD OF THE NEXT COLD FRONT AND
SOME SUNSHINE WED...TRENDED TOWARD WARMER OF GUIDANCE HIGHS...
ESPECIALLY OVER THE SNOW-FREE SOUTHEAST HALF OF THE FCST AREA.
APPEARS BOUNDARY LAYER WINDS WILL KEEP LOW LEVELS STIRRED WED
NIGHT AND TRENDED TOWARD WARMER OF GUIDANCE LOWS. FAVORED A MODEL
CONSENSUS OF HIGHS FOR THU...WHICH BLENDS WELL WITH NEIGHBORING
GRIDS BUT MAY BE TOO WARM WITH MDT/STRONG LOW LEVEL COLD ADVECTION
OVER THE REGION BY MID-DAY. FAVORED THE MODEL CONSENSUS FOR LOWS THU
NIGHT...WHICH ALSO MAY BE TOO WARM IF WINDS ARE LIGHTER THAN
EXPECTED ESPECIALLY OVER THE SNOW-COVERED PORTIONS OF THE FCST AREA.
.LONG TERM...FRIDAY THROUGH MONDAY
332 AM CST TUE DEC 6 2011
LONG-TERM FCST CONFIDENCE AVERAGE. 06.00Z MEDIUM RANGE MODELS IN
REASONABLE AGREEMENT WITH EACH OTHER AND THEIR PREVIOUS RUNS FRI
THRU SUNDAY WITH THE LONGWAVE TROUGH BEING PROGRESSIVE AND HGTS
RISING OVER THE UPPER MIDWEST FRIDAY INTO SUNDAY. COLD SFC HIGH
PRESSURE DRIFTS OVER THE AREA FRI THEN MOVES SOUTH OF THE AREA FOR
SAT/SUN. STRONG LOW LEVEL WARM ADVECTION SPREADS ACROSS THE AREA SAT
INTO SAT NIGHT WITH 925MB TEMPS IN THE 0 TO +4C RANGE BY 12Z SUN.
BELOW/MUCH BELOW NORMAL TEMPS FRI LOOK TO WARM TO ABOVE/MUCH ABOVE
NORMAL BY SUN AS BULK OF THE WARM ADVECTION GOES INTO WARMING UNDER
PARTLY CLOUDY/MOSTLY SUNNY SKIES. RAISED HIGHS A BIT OVER THE
SOUTHEAST HALF OF THE FCST AREA SUN WITH THE LACK OF SNOW COVER.
GFS/ECMWF SOLUTIONS DIVERGE FOR MON. ECMWF SLIDES A COLD FRONT AND
WEAK LOW LEVEL COLD ADVECTION ACROSS THE AREA WHILE GFS TRACKS A LOW
INTO NORTHWEST MN KEEPING THE AREA UNDER LOW LEVEL WARM ADVECTION.
EITHER WAY...APPEARS SOME OF THE SNOW COVER WILL MELT SUN AND MON
WILL SEE CONTINUED ABOVE NORMAL TEMPS. BIGGEST LONG-TERM QUESTION
LOOKS TO BE WILL THERE BE ENOUGH LOWER LEVEL MOISTURE FOR A SMALL
PRECIP CHANCE FOR PARTS OF THE AREA BY LATER MON. MODEL CONSENSUS
DATA USED IN THE DAY 4-7 FCST GRIDS LOOKS TO HAVE ALL OF THIS WELL
TRENDED FOR NOW.
&&
.AVIATION...TODAY AND TONIGHT
537 AM CST TUE DEC 6 2011
MAIN AVIATION CONCERN IS CEILINGS. A VARIETY OF CEILINGS CURRENTLY
ENCOMPASS THE AREA...RANGING FROM IFR TO VFR. WITH A LIGHT WIND
REGIME IN PLACE...IT IS EASILY POSSIBLE CEILINGS AT THE TAF SITES
COULD VARY FOR A WHILE...RISING AND FALLING FROM TIME TO TIME.
HOWEVER...AS THE DAY PROGRESSES...DAYTIME MIXING SHOULD PROMOTE A
GRADUAL RISE IN CEILINGS. ANY CLEARING OF CLOUDS LOOKS TO WAIT
UNTIL THIS EVENING...ASSOCIATED WITH A SURFACE HIGH PRESSURE
RIDGE MOVING WEST TO EAST ACROSS THE TAF SITES. ONCE CLEAR...VFR
CONDITIONS SHOULD THEN PERSIST THROUGH THE REST OF THE NIGHT.
ANOTHER CONCERN IS WINDS LATE TONIGHT. IN THE WAKE OF THE
RIDGE...SOUTHWEST WINDS ARE FORECAST TO INCREASE TO 10-15 KT AT
BOTH TAF SITES. HOWEVER... 35-40 KT WINDS ARE PROGGED 1500-2000 FT
ABOVE THE SURFACE. RIGHT NOW THERE IS NOT ENOUGH WIND TO INSERT
LOW LEVEL WIND SHEAR...BUT IT IS SOMETHING TO MONITOR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
332 AM CST TUE DEC 6 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM... RRS
LONG TERM.... RRS
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
405 AM CST TUE DEC 6 2011
.SHORT TERM...TODAY THROUGH WEDNESDAY.
FORECAST CONCERNS THIS PERIOD...CLOUDS
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE
STRETCHING FROM WESTERN LAKE SUPERIOR INTO WESTERN IA. LOWER CLOUD
CLEARING OVER MUCH OF EASTERN WI AS DRIER AIR...SEEN ON GRB
SOUNDING...WORKING IN. CLOUDS HANGING TOUGH OVER WESTERN PART OF
STATE. SURFACE HIGH WILL CONTINUE TO SHIFT OVER STATE
TODAY...EXITING TONIGHT WITH COLD FRONT ASSOCIATED WITH LOW MOVING
THROUGH NORTHERN CANADA MOVING THROUGH STATE ON WED.
QUESTION IS WHAT WILL HAPPEN WITH CLOUDS TODAY. AREA OF
CONVERGENCE ASSOCIATED WITH WEAK SURFACE TROF OVER WESTERN WI TO
WEAKEN THIS MORNING. SOME MODELS SHOW LOWER CLOUD MOVING BACK INTO
EASTERN WI LATE TODAY AS LOW LEVEL WINDS SHIFT TO THE SOUTHWEST LATE.
SOME SHOW CLOUD DISSIPATING THROUGH THE DAY AS SUPPORT WEAKENS.
HAVE LEANED TOWARDS CANADIAN THAT SHOWS CURRENT CLEARING OVER
EASTERN AND NORTH CENTRAL WI...THOUGH WILL STAY WITH PARTLY
CLOUDY/PARTLY SUNNY WORDING GIVEN CIRRUS MOVING THROUGH AND SOME
UNCERTAINTY. CLOUDS CONTINUE TO MOVE SOUTH OFF LAKE
SUPERIOR/MICHIGAN IN THE FAR EAST. THUS CLEARING SLOWED A BIT FROM
PREVIOUS FORECAST...THOUGH LITTLE CHANGE MADE IN TEMPERATURE
FORECAST.
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY.
MODELS HAD AN UPPER TROUGH OVER MUCH OF THE CONUS EARLY IN THE
PERIOD...WITH THE FLOW BECOMING ZONAL OVER THE UPPER GREAT LAKES BY
EARLY NEXT WEEK.
AN ARCTIC FRONT WILL BRING MUCH COLDER AIR INTO THE FORECAST AREA
ON THURSDAY. HAVE A SLIGHT CHANCE OF SNOW SHOWERS IN VILAS COUNTY
FOR THE END OF THE WORK WEEK. LAPSE RATES OVER LAKE SUPERIOR
SHOULD BE STEEP...BUT WINDS APPEARED TO HAVE TOO MUCH OF A
WESTERLY COMPONENT TO GO AS HIGH AS CHANCE POPS. NEAR OR ABOVE
NORMAL TEMPERATURES CAN BE EXPECTED BY SUNDAY AS A SURFACE RIDGE
PASSES EAST OF THE AREA AND SOUTHWEST WINDS BRING WARMER AIR INTO
THE STATE.
HAVE SOME SLIGHT CHANCE POPS LATE IN THE PERIOD WITH SHORT WAVE
ENERGY AND A SURFACE LOW APPROACHING WISCONSIN. MAY NEED TO GO
WITH HIGHER POPS IN THE AFTERNOON FORECAST PACKAGE OR TOMORROW
MORNING IF CONDITIONS APPEAR MORE FAVORABLE FOR PRECIPITATION.
&&
.AVIATION...A FEW FLURRIES OR SNOW SHOWERS CONTINUE OVER A
CONVERGENT REGION OVER WEST CENTRAL WISCONSIN. OBSERVATIONS OVER
CENTRAL WISCONSIN REPORTING 10 MILES WITH NO WEATHER PRESENT BUT
ANTICIPATE FLURRY ACTIVITY OCCURRING WEST OF A LINE FROM RIB FALLS
TO WISCONSIN RAPIDS INTO WAUSHARA COUNTY. RADARS ALSO SHOWING SOME
RETURNS OVER THE LAKE MICHIGAN SHORELINE WITH NO GROUND TRUTH AND
FINALLY SCATTERED SNOW SHOWERS WERE NOTED OVER VILAS. AS FAR AS
CLOUDS...A SUCKER HOLE OPENED UP NORTHEAST WISCONSIN INCLUDING THE
GRB VICINITY. BUT STILL EXPECT VFR CIGS TO DOMINATE OVERNIGHT
INTO TUESDAY WITH SOME DECREASE IN CLOUDS LATER TUESDAY.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
TE/MG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
332 AM CST TUE DEC 6 2011
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
332 AM CST TUE DEC 6 2011
MAIN FORECAST CONCERNS THIS PACKAGE...CLOUDS AND TEMPERATURES THRU
THE PERIOD.
DATA ANALYSIS AT 06Z HAD A RIDGE OF HIGH PRESSURE EXTENDING FROM
NORTH OF LK SUPERIOR ACROSS MN TO NEB AND WESTERN KS. A LARGE AREA
OF LOW PRESSURE WAS LOCATED OVER NORTH-CENTRAL CAN WITH FALLING
PRESSURES IN THE NORTHERN PLAINS. STRATUS CLOUDS REMAINS TRAPPED
ACROSS THE AREA...UNDER AN INVERSION BETWEEN 850-800MB AND EAST OF
THE SFC RIDGE AXIS. WEST EDGE OF THE CLOUDS WAS NEAR A KDLH-KOTG
LINE...MAKING VERY SLOW PROGRESS EAST/SOUTH. WEAK SFC-925MB TROUGH
AND CONVERGENCE...ALONG WITH THE SLOWLY COOLING LOWER LEVELS
CONTINUED TO SQUEEZE SOME FLURRIES/VERY LIGHT SNOW OUT OF THE
COLUMN OVER MUCH OF WESTERN WI INTO EXTREME EASTERN MN.
NO PROBLEMS NOTED WITH 06.00Z MODEL INITIALIZATIONS. SOLUTIONS QUITE
SIMILAR FOR TODAY THRU THU NIGHT...AT LEAST WITH THE SHORTWAVES AND
LARGER SCALE FEATURES. MODELS STILL STRUGGLING WITH THE LOWER LEVEL
MOISTURE/RH FIELDS AND STRATUS CLOUDS ACROSS THE AREA. DPROG/DT OF
500MB HGTS AT 06.00Z SHOWED MODEL RUNS OF 04.00Z AND 05.00Z VERIFIED
QUITE WELL ACROSS NOAM...FAVORING STRONGER OF EARLIER MODELS WITH
THE NORTHERN PORTION OF THE TROUGH AND FASTER OF EARLIER MODELS WITH
THE SOUTHWEST CONUS PORTION OF THE TROUGH. THRU TODAY/TONIGHT MODELS
TREND TOWARD A TIGHTER/FASTER CONSENSUS WITH THE SOUTHERN PORTION OF
THE TROUGH MOVING EAST INTO THE MID/LOWER MS VALLEY AND WEAKENING OF
THE NORTHERN PORTION OF THE TROUGH AS IT MOVES EAST OF THE REGION.
TREND CONTINUES FASTER WITH THE LOWER MS VALLEY TROUGH WED/WED NIGHT
AS IT TO THE EAST COAST BY 12Z THU. BETTER CONSENSUS FOR BROAD
TROUGHING/NORTHWEST FLOW TO DEVELOP OVER THE NORTH-CENTRAL CONUS/
GREAT LAKES REGION. THIS TROUGH DEEPENS OVER THE MID/UPPER MS VALLEY
THU/THU NIGHT...BUT MINOR DIFFERENCES IN THE TIMING/STRENGTH DETAILS
DEVELOP BY 12Z FRI. OVERALL BETTER RUN-TO-RUN CONSISTENCY FOR TODAY
THRU THU NIGHT SHOWN BY ECMWF...ESPECIALLY WITH THE SOUTHERN STREAM
ENERGY EARLY IN THE PERIOD. CHECK OF OBS VS. MODEL DATA AT 06Z
SHOWED MODELS ALL QUITE GOOD WITH THE CENTRAL CONUS SFC MASS
FIELDS...THOUGH AGAIN CONTINUED TO STRUGGLE WITH THE LOWER LEVEL RH
AND STRATUS DECKS TRAPPED ACROSS THE REGION. ECMWF/ RUC LOOK TO BE
DOING BEST WITH THE 925MB RH/STATUS CLOUDS OVER MN/ WI/IA WHILE ONLY
MODEL SOME INDICATION OF THE FLURRIES WAS THE GFS. THUS NO CLEAR
DETERMINISTIC MODEL FAVORITE. WITH MODELS TRENDING TOWARD A TIGHTER
CONSENSUS MUCH OF THE PERIOD...FAVORED THE CONSENSUS. SHORT TERM
FCST CONFIDENCE AVERAGE TO GOOD THIS CYCLE.
IN THE SHORT TERM...LOW CLOUDS/CLEARING REMAIN PROBLEMATIC TODAY/
TONIGHT WITH TYPICAL POOR MODEL PERFORMANCE ON THIS AND THE TIME OF
YEAR WHEN LOW CLOUDS LIKE TO HANG TOUGH. MODEL CONSENSUS KEEPS 70+
PERCENT 925MB RH OVER THE CENTRAL/EAST PARTS OF THE FCST AREA THRU
THE DAY WITH ONLY SLOW EROSION/ADVECTION ON THE WESTERN SIDE.
RAISED CLOUD COVER IN SKY GRIDS TO REFLECT A SLOWER/NON CLEARING
TODAY. MOVED THE CLEARING INTO TONIGHT WITH INCREASING WEST SFC-
850MB FLOW NORTH OF THE LOW LEVEL RIDGE AXIS TO FINALLY ADVECT THE
MOISTURE EAST AND OUT OF THE AREA. SFC-925MB TROUGH WEAKENS THRU
THIS MORNING...BUT GIVEN SLOW MOVEMENT OF THE LOW LEVEL FEATURES...
LINGERED SCT FLURRIES OVER THE NORTH HALF OF THE FCST AREA WHERE
RADAR REFLECTIVITY/SFC OBS CONTINUED TO DETECT/REPORT FLURRIES AS OF
09Z. REST OF SHORT-TERM PERIOD GENERALLY COOL/QUIET. SHORTWAVE
ENERGY PASSES NORTH OF THE FCST AREA WED/WED NIGHT WITH BULK OF
FORCING/LIFT AND 850-500MB MOISTURE/SATURATION REMAINING NORTH OF
THE FCST AREA. COLD/DRY AIRMASS SETTLES ACROSS THE AREA IN THE WAKE
OF THIS SHORTWAVE TROUGH FOR THU/THU NIGHT. THIS AS MORE SHORTWAVE
ENERGY DROPS SOUTHEAST ACROSS THE NORTHERN PLAINS FOR THU/THU NIGHT.
BULK OF THE LOWER LEVEL THERMO-DYNAMIC FORCING AND INCREASE OF
MOISTURE IN THE 925-700MB LAYER REMAINS SOUTH OF THE FCST AREA
THU/THU NIGHT. ONLY LINGERED A SMALL -SN CHANCE ACROSS THE EXTREME
SOUTH END OF THE FCST AREA THU NIGHT TO BLEND WITH NEIGHBORING
GRIDS. SATURATION OF THE COLUMN OVER THE NORTH END OF THE FCST AREA
THU/THU NIGHT...NORTH OF THE SHORTWAVE TRACK...AN ISSUE IN THE
COLDER COLUMN THERE. MAY YET SEE SCT FLURRIES ALONG/NORTH OF HWY 29
THU/THU NIGHT BUT LEFT THIS DRY FOR NOW. GENERALLY CARRIED PARTLY
CLOUDY TO MOSTLY CLEAR SKIES FOR WED THRU THU NIGHT.
HIGH/LOW TEMPERATURES PROBLEMATIC WITH SNOW COVERING THE NORTHWEST
HALF OF THE FCST AREA WHILE THE SOUTHEAST HALF IS SNOW-FREE. WITH
MORE CLOUDS/OVERCAST TODAY...TRENDED HIGHS FOR MINIMAL DIURNAL
SWING AND AT OR BELOW NUMERICAL GUIDANCE. WITH PARTLY CLOUDY SKIES
TONIGHT BUT SOME SOUTHWEST GRADIENT WINDS...FAVORED A BLEND OF THE
GUIDANCE LOWS. SOUTHWEST/WEST WINDS AHEAD OF THE NEXT COLD FRONT AND
SOME SUNSHINE WED...TRENDED TOWARD WARMER OF GUIDANCE HIGHS...
ESPECIALLY OVER THE SNOW-FREE SOUTHEAST HALF OF THE FCST AREA.
APPEARS BOUNDARY LAYER WINDS WILL KEEP LOW LEVELS STIRRED WED
NIGHT AND TRENDED TOWARD WARMER OF GUIDANCE LOWS. FAVORED A MODEL
CONSENSUS OF HIGHS FOR THU...WHICH BLENDS WELL WITH NEIGHBORING
GRIDS BUT MAY BE TOO WARM WITH MDT/STRONG LOW LEVEL COLD ADVECTION
OVER THE REGION BY MID-DAY. FAVORED THE MODEL CONSENSUS FOR LOWS THU
NIGHT...WHICH ALSO MAY BE TOO WARM IF WINDS ARE LIGHTER THAN
EXPECTED ESPECIALLY OVER THE SNOW-COVERED PORTIONS OF THE FCST AREA.
.LONG TERM...FRIDAY THROUGH MONDAY
332 AM CST TUE DEC 6 2011
LONG-TERM FCST CONFIDENCE AVERAGE. 06.00Z MEDIUM RANGE MODELS IN
REASONABLE AGREEMENT WITH EACH OTHER AND THEIR PREVIOUS RUNS FRI
THRU SUNDAY WITH THE LONGWAVE TROUGH BEING PROGRESSIVE AND HGTS
RISING OVER THE UPPER MIDWEST FRIDAY INTO SUNDAY. COLD SFC HIGH
PRESSURE DRIFTS OVER THE AREA FRI THEN MOVES SOUTH OF THE AREA FOR
SAT/SUN. STRONG LOW LEVEL WARM ADVECTION SPREADS ACROSS THE AREA SAT
INTO SAT NIGHT WITH 925MB TEMPS IN THE 0 TO +4C RANGE BY 12Z SUN.
BELOW/MUCH BELOW NORMAL TEMPS FRI LOOK TO WARM TO ABOVE/MUCH ABOVE
NORMAL BY SUN AS BULK OF THE WARM ADVECTION GOES INTO WARMING UNDER
PARTLY CLOUDY/MOSTLY SUNNY SKIES. RAISED HIGHS A BIT OVER THE
SOUTHEAST HALF OF THE FCST AREA SUN WITH THE LACK OF SNOW COVER.
GFS/ECMWF SOLUTIONS DIVERGE FOR MON. ECMWF SLIDES A COLD FRONT AND
WEAK LOW LEVEL COLD ADVECTION ACROSS THE AREA WHILE GFS TRACKS A LOW
INTO NORTHWEST MN KEEPING THE AREA UNDER LOW LEVEL WARM ADVECTION.
EITHER WAY...APPEARS SOME OF THE SNOW COVER WILL MELT SUN AND MON
WILL SEE CONTINUED ABOVE NORMAL TEMPS. BIGGEST LONG-TERM QUESTION
LOOKS TO BE WILL THERE BE ENOUGH LOWER LEVEL MOISTURE FOR A SMALL
PRECIP CHANCE FOR PARTS OF THE AREA BY LATER MON. MODEL CONSENSUS
DATA USED IN THE DAY 4-7 FCST GRIDS LOOKS TO HAVE ALL OF THIS WELL
TRENDED FOR NOW.
&&
.AVIATION...THROUGH 06Z WEDNESDAY
1045 PM CST MON DEC 5 2011
PERSISTENT LOW LEVEL SATURATION...PER RH FIELDS AND BUFKIT
SOUNDINGS...SUGGEST THAT THE MVFR CIGS WILL HOLD INTO TUE
AFTERNOON/EVENING. AN UPPER LEVEL SHORTWAVE TROUGH WILL HELP
SWEEP THE LOW STRATUS TO THE EAST...AND MOST OF TUE NIGHT LOOKS
SCT-SKC. BY WED MORNING CLOUDS ASSOCIATED WITH THE TROUGH WILL SLIDE
IN...AND THERE COULD BE ANOTHER PERIOD OF MVFR CIGS IN THE
AFTERNOON.
A FEW FLURRIES WILL CONTINUE THROUGH THE OVERNIGHT HOURS...BUT DON/T
SEE ANY REDUCTIONS TO VSBY. BELIEVE ANY THREAT FOR -FZDZ HAS ALSO
ENDED.
NORTHWEST WINDS WILL SWING TO THE SOUTHWEST BY LATE TUE
AFTERNOON...AHEAD OF THAT SHORTWAVE...BUT SHIFT BACK TO THE
NORTHWEST ON WED AS THE SYSTEM PASSES EAST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
332 AM CST TUE DEC 6 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM... RRS
LONG TERM.... RRS
AVIATION..... RIECK
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1057 PM CST MON DEC 5 2011
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
.SHORT TERM...TONIGHT AND TUESDAY.
LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW THE STATE OF
WISCONSIN LOCATED BETWEEN A COLD FRONT RUNNING UP THE EASTERN SIDE
OF THE APPALACHIANS...AND A POLAR SURFACE HIGH STRETCHING ACROSS THE
DAKOTAS EARLY THIS AFTERNOON. A WEAK SURFACE TROUGH REMAINS A
NUISANCE WHICH HANGS BACK FROM JUST SOUTH OF MILWAUKEE TO EAU
CLAIRE. RADAR RETURNS HAVE GRADUALLY ERODED OVER CENTRAL AND
EAST-CENTRAL WISCONSIN OVER THE COURSE OF THE DAY...THOUGH BEEFIER
RETURNS AND SURFACE OBS SHOW LIGHT SNOW SHOWERS OCCURRING OVER
WESTERN WISCONSIN. SOME HOLES IN THE CLOUDS ARE TRYING TO DEVELOP
OVER NORTHEAST WISCONSIN...AND PERHAPS INTO CENTRAL WISCONSIN AS
WELL. AS THE SURFACE HIGH SHIFTS EAST TONIGHT...CLOUD TRENDS AND
TEMPS ARE THE MAIN FORECAST CONCERNS.
TONIGHT...HIGH PRESSURE OVER THE NORTHERN PLAINS WILL BUILD EAST
OVER THE NORTHERN MISSISSIPPI VALLEY. HOWEVER...FLOW WILL CONTINUE
TO BE OUT OF THE NORTH AND LIGHTLY ADVECTING CLOUDS OFF LAKE
SUPERIOR. IN ADDITION...12Z GUIDANCE SUPPORTS LINGERING LOW LEVEL
CONVERGENCE OVER CENTRAL WISCONSIN THAT WILL KEEP AN AREA OF
ENHANCED RH IN PLACE. KEPT A FLURRY MENTION OVER THE FAR WESTERN
CWA TO ACCOUNT FOR THIS. WITH PLENTY OF CLOUDS UPSTREAM...HAVE A
HARD TIME GOING BELOW MOSTLY CLOUDY CONDITIONS. THERE WILL BE
UNDOUBTEDLY SUCKER HOLES THAT WILL DEVELOP WITHIN THE
STRATUS...MOSTLY LIKELY WITHIN THE DOWNSLOPING AREAS OF NORTHEAST
WISCONSIN. WILL PLAY THE PROBABILITY THAT SCT CONDITIONS DEVELOP
THERE...BUT LEAVE MOSTLY CLOUDY CONDITIONS ELSEWHERE...WITH SCT SNOW
SHOWERS OVER THE SNOW BELT OF N-C WISCONSIN. LOWS IN THE LOWER
TEENS NORTH TO MIDDLE 20S SOUTHEAST. TEMPS COULD BE MUCH COLDER
OVER THE SNOW PACK OF N-C WISCONSIN IF HOLES IN THE CLOUDS DO
DEVELOP THERE.
TUESDAY...HIGH PRESSURE BUILDS INTO THE REGION TOMORROW. ANY
SURFACE CONVERGENCE ALONG THE LINGERING TROUGH OVER CENTRAL
WISCONSIN IS PROGGED TO DISSIPATE IN THE MORNING...BUT MODELS
INDICATE THE REMNANTS OF THE ENHANCED RH MOVING EAST AS LIGHT SW
FLOW DEVELOPS. ALSO SEE SIGNS OF STEEP LOW LEVEL LAPSE RATES WITH
HEATING OF THE DAY THAT POINTS TOWARDS STRATO-CU DEVELOPING. WITH
CLOUDS UNDER THE HIGH CURRENTLY...WILL SIDE MORE PESSIMISTICALLY
WITH CLOUD COVER...WHICH WILL KEEP MOSTLY CLOUDY CONDITIONS OVER
NORTH-CENTRAL WISCONSIN FOR THE MORNING...AND PARTLY CLOUDY
CONDITIONS EVERYWHERE FOR THE AFTERNOON. HIGHS RANGING FROM THE
LOWER 20S NORTH TO AROUND 30 DEGREES SOUTHEAST.
.LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...THE MAIN FCST
CONCERN IS THE ARRIVAL OF ARCTIC AIR LATER IN THE WEEK.
SHORT-WAVE ENERGY CURRENTLY OVER THE GULF OF ALASKA WILL TOP THE
WEST COAST RIDGE...THEN HELP TO CARVE A BROAD TROF OVER THE
CENTRAL U.S. BY THURSDAY. A SURGE OF ARCTIC AIR IS EXPECTED TO
ARRIVE IN WI ON THURSDAY...WITH H8 TEMPS PLUMMETING TO -16 TO
-20 C BY FRIDAY. THIS WILL LEAD TO OUR COLDEST TEMPERATURES SO
FAR THIS SEASON. THE COLDER WEATHER WILL NOT LAST LONG...AS
SOUTHWEST WINDS DEVELOP IN THE WAKE OF THE RETREATING ARCTIC
HIGH OVER THE WEEKEND. H8 TEMPS ARE EXPECTED TO SURGE TO 0 TO
+4 C BY SATURDAY NIGHT/SUNDAY.
A WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION ON
WEDNESDAY...WITH A STRONGER ARCTIC FRONT ARRIVING ON THURSDAY.
HAVE BEEN WATCHING FOR POSSIBLE SNOW DEVELOPMENT AS THE RRQ OF A
STG UPPER JET INTERACTS WITH THE ARCTIC FRONT THURSDAY NIGHT
INTO FRIDAY...BUT THE CONCENSUS OF THE MODELS...INCLUDING THE
12Z/MON ECMWF...IS THAT SNOW WILL DEVELOP TO OUR SOUTH AND EAST.
WILL NOT CARRY ANY POPS AT THIS TIME...BUT SUBSEQUENT SHIFTS WILL
STILL NEED TO KEEP AN EYE ON THIS.
DESPITE THE PRESENCE OF A COLD AIR MASS FROM WEDNESDAY THROUGH
FRIDAY NIGHT...WIND TRAJECTORIES WILL BE TOO WESTERLY FOR ANY
APPRECIABLE LK-EFFECT SNOW.
MODELS HAVE BACKED OFF SLIGHTLY ON THE MAGNITUDE OF THE COLD SNAP
LATE IN THE WORK WEEK...WITH H8 TEMPS TRENDING A FEW DEGREES
WARMER. EVEN SO...STILL EXPECT MAX TEMPS TO BE ABOUT 10 DEGREES
BLO NORMAL ON FRIDAY. THE COLDER WEATHER WILL BE SHORT-LIVED...
WITH ABOVE NORMAL TEMPERATURES QUICKLY RETURNING BY SUNDAY.
A WEAK COLD FRONT MAY IMPACT THE REGION ON MONDAY...BUT SHOULD
NOT HAVE ANY SIGNIFICANT IMPACT ON OUR WEATHER.
&&
.AVIATION...A FEW FLURRIES OR SNOW SHOWERS CONTINUE OVER A
CONVERGENT REGION OVER WEST CENTRAL WISCONSIN. OBSERVATIONS OVER
CENTRAL WISCONSIN REPORTING 10 MILES WITH NO WEATHER PRESENT BUT
ANTICIPATE FLURRY ACTIVITY OCCURRING WEST OF A LINE FROM RIB FALLS
TO WISCONSIN RAPIDS INTO WAUSHARA COUNTY. RADARS ALSO SHOWING SOME
RETURNS OVER THE LAKE MICHIGAN SHORELINE WITH NO GROUND TRUTH AND
FINALLY SCATTERED SNOW SHOWERS WERE NOTED OVER VILAS. AS FAR AS
CLOUDS...A SUCKER HOLE OPENED UP NORTHEAST WISCONSIN INCLUDING THE
GRB VICINITY. BUT STILL EXPECT VFR CIGS TO DOMINATE OVERNIGHT
INTO TUESDAY WITH SOME DECREASE IN CLOUDS LATER TUESDAY.
TDH
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1045 PM CST MON DEC 5 2011
.SHORT TERM...
245 PM CST MON DEC 5 2011
BIGGEST FORECAST CONCERN IS ON CLOUDS AND TEMPERATURES...WITH LIGHT
PRECIPITATION CHANCES THIS EVENING ALSO A CONCERN.
18Z WATER VAPOR IMAGERY SHOWS SHORTWAVE TROUGH OVER
MINNESOTA...WHILE AT THE SURFACE A WEAK TROUGH WAS WORKING ITS WAY
THROUGH THE FORECAST AREA...BUT WAS WEAKENING WITH TIME. THIS
COMBINATION WAS PRODUCING WEAK LIFT THROUGH SATURATED LOWER LAYER
AND THUS SURFACE REPORTS INDICATING MAINLY LIGHT SNOW AND
FLURRIES...WITH SOME PATCHY FREEZING DRIZZLE.
05.12Z MODELS AGAIN IN GOOD AGREEMENT WITH THEIR MASS FIELDS. THERE
IS SOME DIFFERENCES IN SPEED OF COLDER PLUNGE OF AIR ON
THURSDAY...WITH THE NAM THE FASTEST. ONLY OTHER DIFFERENCE NOTED IS
GFS A LITTLE FASTER IN PUSHING THE STRATUS OUT ON TUESDAY.
FOR TONIGHT...SHORTWAVE IN MINNESOTA ROTATES INTO NORTHWEST
WISCONSIN. MODEL SOUNDINGS INDICATE WEAK LIFT CONTINUES IN THE
SATURATED LOWER LAYER DURING THE EVENING. 05.15Z RUC SOUNDINGS
QUESTIONABLE WITH REGARDS TO ICE IN THE CLOUD LAYER...WHILE NAM
SOUNDINGS SUGGEST MORE ICE. BASED ON REPORTS FROM THIS AFTERNOON
MENTION FLURRIES AND PATCHY FREEZING DRIZZLE FOR THE EVENING HOURS.
WITH THE CLOUDS DID GO ON THE WARMER SIDE OF THE GUIDANCE NUMBERS
FOR LOWS TONIGHT.
ON TUESDAY...GFS A LITTLE FASTER IN PUSHING THE STRATUS OUT OF THE
AREA...WHILE THE NAM KEEPS 850MB-925MB MOISTURE OVER THE AREA
THROUGHOUT THE DAY AND NOT CLEARING UNTIL EVENING. DID TAKE A
COMPROMISE...WITH A CLEARING TREND FROM WEST TO EAST DURING THE
AFTERNOON HOURS. TEMPERATURES WILL BE TRICKY WITH THE CLOUDS...BUT
WITH THE MORE PESSIMISTIC OUTLOOK DID GO WITH THE COOLER OF THE
GUIDANCE NUMBERS.
DO EXPECT CLEAR SKIES...AT LEAST FOR A SHORT PERIOD OF TIME TUESDAY
NIGHT. HOWEVER...ANOTHER SHORTWAVE BEGINS TO DROP SOUTHWARD OUT OF
SOUTHERN CANADA LATE TUESDAY NIGHT...AND MODELS HINT AT AN INCREASE
IN HIGH LEVEL CLOUDS. THESE CLOUDS THEN DROP ACROSS THE AREA ON
WEDNESDAY AND WEDNESDAY NIGHT AHEAD OF THE ASSOCIATED COLD FRONT.
TEMPERATURES LOOK TO BE A LITTLE MILDER AHEAD OF THE FRONT...BUT
STILL BELOW NORMAL WITH HIGHS FROM THE MIDDLE 20S IN THE SNOW
COVERED LOCATIONS...TO THE LOWER 30S IN THE NON SNOW COVERED AREAS.
ON THURSDAY COLD AIR BEGINS TO SURGE INTO THE AREA BEHIND THE FRONT.
AS MENTIONED BEFORE NAM QUICKER IN MOVING THIS COLD AIR INTO THE
REGION AND AGAIN USED A MODEL CONSENSUS FOR HIGHS. 05.12 GFS AND
ECMWF ALSO GENERATING SOME LIGHT PRECIPITATION ALONG THE LEADING
EDGE OF THE COLD AIR ACROSS IOWA IN BAND OF WEAK FRONTOGENESIS. WITH
THE BULK OF PUSH OF COLD AIR THURSDAY NIGHT...DID ADD SOME LOWER END
SNOW PROBABILITIES ACROSS NORTHEAST IOWA AND SOUTHWEST WISCONSIN.
.LONG TERM...
245 PM CST MON DEC 5 2011
A DRY NORTHWEST LOW PATTERN WILL CONTINUE FOR FRIDAY AND SATURDAY
AND THIS WILL LEAD TO BELOW NORMAL TEMPERATURES. THE FLOW WILL
BECOME MORE ZONAL ON SUNDAY AS A TROUGH BUILDS INTO THE WESTERN
CONUS. AS THE TROUGH PROGRESSES INTO THE CENTRAL SECTIONS OF THE
COUNTRY...THE FLOW WILL BECOME MORE SOUTHWESTERLY. DRY CONDITIONS
WILL CONTINUE THROUGH MONDAY...BUT WITH A MORE SOUTHERLY
WIND...TEMPERATURES WILL WARM SATURDAY AND SUNDAY...WITH HIGHS
EXPECTED IN THE 30S BOTH SUNDAY AND MONDAY.
&&
.AVIATION...
1045 PM CST MON DEC 5 2011
PERSISTENT LOW LEVEL SATURATION...PER RH FIELDS AND BUFKIT
SOUNDINGS...SUGGEST THAT THE MVFR CIGS WILL HOLD INTO TUE
AFTERNOON/EVENING. AN UPPER LEVEL SHORTWAVE TROUGH WILL HELP
SWEEP THE LOW STRATUS TO THE EAST...AND MOST OF TUE NIGHT LOOKS
SCT-SKC. BY WED MORNING CLOUDS ASSOCIATED WITH THE TROUGH WILL SLIDE
IN...AND THERE COULD BE ANOTHER PERIOD OF MVFR CIGS IN THE AFTERNOON.
A FEW FLURRIES WILL CONTINUE THROUGH THE OVERNIGHT HOURS...BUT DON/T
SEE ANY REDUCTIONS TO VSBY. BELIEVE ANY THREAT FOR -FZDZ HAS ALSO
ENDED.
NORTHWEST WINDS WILL SWING TO THE SOUTHWEST BY LATE TUE
AFTERNOON...AHEAD OF THAT SHORTWAVE...BUT SHIFT BACK TO THE
NORTHWEST ON WED AS THE SYSTEM PASSES EAST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
245 PM CST MON DEC 5 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM... RABERDING
LONG TERM.... RABERDING
AVIATION..... RIECK
AREA FORECAST DISCUSSION
NWS ALBANY NY
1245 AM EST THU DEC 8 2011
.SYNOPSIS...
A STORM SYSTEM WILL LIFT NORTHEAST FROM THE DELMARVA REGION THIS
EVENING...TO THE EAST END OF LONG ISLAND AROUND MIDNIGHT...AND
THEN INTO THE GULF OF MAINE THURSDAY MORNING. THIS STORM TRACK
WILL RESULT IN RAIN CHANGING TO SNOW THIS EVENING ACROSS MUCH OF
THE REGION WITH SIGNIFICANT SNOWFALL ACCUMULATIONS OVERNIGHT IN
MANY AREAS. THE HEAVIEST SNOW IS EXPECTED TO FALL ACROSS THE
NORTHERN TACONICS...EASTERN CATSKILLS...BERKSHIRES AND SOUTHERN
GREEN MOUNTAINS. HEAVY RAIN WILL CONTINUE TO FALL OVERNIGHT ACROSS
THE MID HUDSON VALLEY AND LITCHFIELD HILLS.
&&
.NEAR TERM /THROUGH THURSDAY/...
AS OF 930PM RADAR FSI CROSS SECTIONS AND SPOTTER REPORTS HAVE RAIN
CHANGING TO SNOW AROUND THE GREATER CAPITAL DISTRICT. THIS IS
RUNNING AN HOUR OR TWO BEHIND GRIDS AND MADE MINOR CHANGES. THIS
PROCESS WILL RAPIDLY CHANGE RAIN OVER TO SNOW IN NEXT 1-2 HOURS.
00UTC NAM IN LINE WITH PVS QPF AND THINKING. NO DEPARTURES THERE.
ONCE PCPN CHANGES OVER BURST OF SNOW FOR SEVERAL HOURS IN MASSIVE
TILTED FRONTOGENESIS AS MESOSCALE BAND HAS SET UP FM SW VT TO
CATSKILLS (CSTAR) WHILE PCPN MAY BE CHANGING OVER 1-2 HOURS
LATER...DONT THINK IT WILL SIGNIFICANTLY ALTER CURRENT THINKING ON
AMOUNTS OR HEADLINES GIVEN CHARACTER AND FORCING OF THE SNOW
OVERNIGHT.
ALL 3 HOUR PRESSURE MAX FALLS ARE NOW OFFSHORE NJ/DELMARVA. RAPID
DEEPENING WILL OCCUR NEXT FEW HOURS AS 500HPA SHORT WAVE INTERACT
WITH STRONG BAROCLINIC ZONE ALONG COAST.
AS OF 7PM...NOT MAKING ANY CHANGES ATTM. AWAITING CHANGE OVER TO
SNOW. ON ALB 00UTC ALB SOUNDING +4C WARM NOSE REMAINS AT 3500 MSL.
FSI CROSS SECTIONS CAPPI INDICATE BRIGHT BAND LOWERING TO GROUND IN
MONTGOMERY/SCHOHARIE COUNTIES...BUT ONLY ONE REPORT OF SNOW IN
WEST SCHOHARIE COUNTY AN HOUR AGO.
BANDLETS (CSTAR III) HAVE SET UP ACROSS RGN WITH SOME ALONG BRIGHT
BAND AXISES AND OTHERS IN RN TO +RN AREAS. 18UTC NAM/GFS SHOW ALL
THE RIGHT FEATURES FOR FORMATION OF A MAJOR BAND OVER FCA. 20UVM
IN MAX DENDRITIC GROWN ZONE BY 03UTC...STRONG TILTED FRONTOGENESIS
AND EPV. SO THE STAGE IS SET...JUST AWAITING THE ARRIVAL OF THE
COLDER AIR OR ITS DYNAMIC CREATION.
SFC PRES FALLS HAVE SHIFTED TO NJ-DELMARVA COAST BUT 3HR VALUES
REMAIN REMAIN ON ORDER OF 4-6MB. WX WATCH CONTINUES.
WINTER STORM WARNINGS ARE IN EFFECT FOR TONIGHT FOR THE EASTERN
CATSKILLS...NORTHERN TACONICS...BERKSHIRES AND SOUTHERN GREEN
MOUNTAINS AND WINTER WEATHER ADVISORIES IN EFFECT FOR THE
SOUTHEAST ADIRONDACKS...LAKE GEORGE SARATOGA REGION...EASTERN
MOHAWK VALLEY...SACANDAGA REGION...GREATER CAPITAL DISTRICT AND
CENTRAL TACONICS. A FLOOD WATCH IS IN EFFECT THROUGH THURSDAY
MORNING FOR THE MID HUDSON VALLEY...SOUTHERN TACONICS AND
LITCHFIELD HILLS.
SNOWFALL ACCUMULATIONS ARE GENERALLY EXPECTED TO BE 3 TO 8 INCHES
IN THE ADVISORY AREA AND 5 TO 12 INCHES IN THE WARNING AREA EXCEPT
ACROSS THE CENTRAL AND SOUTHEAST CATSKILLS...NORTHERN BERKSHIRES
AND HIGHER TERRAIN OF THE SOUTHERN GREEN MOUNTAINS WHERE 8 TO 16
INCHES OF SNOW IS EXPECTED. TOTAL RAINFALL AMOUNTS IN THE FLOOD
WATCH AREA ARE EXPECTED TO BE IN THE 1.75 TO 2.25 INCH RANGE.
AS OF 530 PM EST...CLOUD TOPS CONTINUE TO COOL ACROSS THE FA WITH
21Z KALB SOUNDING INDICATING A WARM TONGUE OF 4C AT AROUND 875 MB
WITH THE FREEZING LEVEL AT AROUND 775 MB OR 6.6 KFT. HAVE RECEIVED
A REPORT OF 1 INCH OF SNOW THUS FAR IN CHARLOTTEVILLE IN SCHOHARIE
COUNTY WITH HEAVY WET SNOW AND A TEMP OF 36 DEGREES AT AN
ELEVATION OF AROUND 1500 FEET. EXPECT A RAPID CHANGEOVER TO SNOW
THIS EVENING ACROSS MUCH OF THE FA MAINLY BETWEEN 00Z AND 03Z WITH
VERY HEAVY SNOW EXPECTED TO FALL DURING MUCH OF THE NIGHT BEFORE
TAPERING OFF LATE. THE ONLY AREAS WHICH ARE NOT EXPECTED TO
RECEIVE MUCH SNOW ARE FAR NORTHWEST PORTIONS OF THE FA INCLUDING
THE WESTERN ADIRONDACKS AND WESTERN MOHAWK VALLEY WHERE VERY
LITTLE QPF EXPECTED...NORTHERN FRINGE OF PCPN SHIELD AND FAR
SOUTHEAST PORTION OF FA WHICH WILL REMAIN TOO WARM FOR MUCH IN THE
WAY OF SNOW MAINLY FROM THE MID HUDSON VALLEY EAST TO THE
LITCHFIELD HILLS WHERE A FLOOD WATCH IS IN EFFECT.
MANY FAVORABLE FACTORS FOR HEAVY SNOW ARE IN PLACE ACROSS MUCH OF
THE FA WITH THE MOST SIGNIFICANT FACTORS BEING IMPRESSIVE
FRONTOGENESIS H8-H7 EXTENDING FROM THE CATSKILLS NORTHEAST TO
SOUTHERN VERMONT AT 00Z AND THEN SHIFTING TO AN ORIENTATION FROM
JUST EAST OF THE CAPITAL DISTRICT THROUGH THROUGH THE NORTHERN
BERKSHIRES INTO SOUTHERN VERMONT AT 06Z. AS THE EVENING WEARS ON
THE SNOW GROWTH REGION BECOMES INCREASINGLY MORE FAVORABLE WITH
THE -12 TO -18 C TEMP SLICING THROUGH A REGION OF +20 UBAR/SEC. IN
ADDITION IMPRESSIVE EPV EXISTS IN LOWER LEVELS ESPECIALLY BTWN 00Z
AND 06Z. THE LATEST HRRR COL MAX REFLECTIVITY ALSO INDICATES
IMPRESSIVE BANDED PCPN ESPECIALLY ACROSS THE HIGHER TERRAIN IN THE
WARNING AREA BETWEEN 03Z AND 06Z WITH THE BACK EDGE OF THE PCPN
SHIELD EXITING THE FA FROM WEST TO EAST BETWEEN 08Z AND 10Z.
EXPECT LOW TEMPS TONIGHT TO RANGE FROM THE MID 20S NORTHWEST TO
MID 30S FAR SOUTHEAST.
ON THURSDAY EXPECT IMPROVING CONDITIONS WITH HIGH PRESSURE MOVING
IN AND MAINLY DRY CONDITIONS WITH HIGHS RANGING FROM THE UPPER
20S TO LOWER 30S NORTHWEST TO LOWER 40S FAR SOUTHEAST.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
THU NT...BACKING LOW LEVEL WINDS SHOULD ALLOW ANY LINGERING SNOW
BANDS/SNOW SHOWERS TO SHIFT NORTHWARD INTO THE WESTERN
ADIRONDACKS...WITH ADDITIONAL ACCUMS POSSIBLE BEFORE INVERSION
HEIGHTS LOWER AND DIMINISH INTENSITY OF ANY SNOWBANDS.
ELSEWHERE...INITIALLY CLEAR TO PARTLY CLOUDY SKIES SHOULD BECOME
MOSTLY CLOUDY LATER AT NIGHT AS MID LEVEL ISENTROPIC LIFT INCREASES
AHEAD OF NEXT APPROACHING SHORTWAVE. EXPECT MINS TO FALL INTO THE
TEENS AND 20S...WARMEST ACROSS VALLEY REGIONS.
FRI-SAT...UPPER LEVEL TROUGH WILL APPROACH FROM THE W...AND PASS
ACROSS FRI NT. A SFC COLD FRONT ASSOCIATED WITH THIS FEATURE WILL
CROSS THE REGION LATE FRI OR FRI EVE...PRECEDED AND ACCOMPANIED BY
SNOW SHOWERS. THEN...BEHIND THE FRONT...BANDS OF SNOW SHOWERS AND
POSSIBLE SNOW SQUALLS WILL BE POSSIBLE...INITIALLY FAVORING PORTIONS
OF THE WESTERN MOHAWK VALLEY/SCHOHARIE VALLEY...THEN GRADUALLY
SHIFTING NORTHWARD INTO THE WESTERN ADIRONDACKS BY SAT. THERE IS
SOME POTENTIAL FOR LOCALLY HEAVY SNOWFALL AMTS WITHIN SOME OF THESE
BANDS...AND WILL MENTION THIS POSSIBILITY IN THE HWO...WITH GREATEST
THREAT ACROSS THE WESTERN ADIRONDACKS. EXPECT FRI MAXES TO REACH THE
30S IN MOST AREAS...EXCEPT AROUND OR INTO THE LOWER 40S WITHIN THE
VALLEYS...WITH 20S ACROSS HIGHER ELEVATIONS. COLDER AIR BEHIND THE
FRONT WILL MOVE IN FOR FRI NT AND SAT...WITH FRI NT MINS IN THE
TEENS AND LOWER 20S...AND SAT MAXES MAINLY IN THE 30S WITHIN
VALLEYS...AND 20S ACROSS HIGHER ELEVATIONS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THIS PERIOD WILL BE FAIRLY QUIET AS HIGH PRESSURE BUILDS INTO THE
MID ATLANTIC REGION SATURDAY NIGHT AND DOMINATES OUR WEATHER INTO
THE EARLY PART OF THE COMING WEEK. A CHANCE OF SOME LAKE ENHANCED
SNOW SHOWERS SATURDAY NIGHT...THEN DRY UNTIL TUESDAY NIGHT WHEN A
WEAK BOUNDARY BRINGS ABOUT SOME SNOW AND RAIN SHOWERS WEST OF THE
HUDSON VALLEY WEDNESDAY.
THE PERIOD STARTS OFF CHILLY...LOWS FROM AROUND 10 TO 20 ABOVE ON
SUNDAY MORNING...WITH HIGHS SUNDAY ONLY IN THE UPPER 20S TO THE
MID 30S. TEMPERATURES WILL GRADUALLY MODERATE WITH HIGHS RISING
TO THE UPPER 30S AND LOWER 40S BY TUESDAY AFTERNOON.
FOR THE MOST PART...USED HPC GUIDANCE TO POPULATE THE GRIDS.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AS OF 0530Z...PCPN HAS CHANGED OVER TO SNOW AT THE KGFL/KALB/KPOU
TAF SITES. EXPECT THE SNOW AND MAINLY IFR CONDITIONS TO CONTINUE
UNTIL AROUND 08Z TO 09Z...WITH A RAPID IMPROVEMENT TO VFR CONDITIONS
AFTER 09Z. VFR CONDITIONS THEREAFTER UNTIL THE END OF THE TAF PERIOD
AT 06Z FRIDAY.
NORTHERLY WINDS AT 5 TO 15 KTS WITH SOME GUSTS TO 20 KTS POSSIBLE AT
THE TAF SITES (PRIMARILY KALB/KPOU)...THEN BECOMING NORTHWEST AFTER
THE SNOW ENDS AND INCREASING TO 10 TO 15 KTS BY MID MORNING WITH
GUSTS OF 20 TO 25 KTS. BY LATE IN THE AFTERNOON THE WINDS WILL
SUBSIDE TO 10 KTS OR LESS AN DSHIFT TO THE SOUTHWEST...THEN LIGHT
SOUTH OR SOUTHWEST WINDS AFTER 00Z FRIDAY.
OUTLOOK...
LATE THU NT-SAT...MAINLY VFR...SLIGHT CHC -SHSN. BREEZY.
SUN-MON...VFR...NO SIG WX.
&&
.HYDROLOGY...
A SIGNIFICANT MIXED PRECIPITATION EVENT WAS OCCURRING ACROSS THE
REGION WITH STORM TOTAL LIQUID AMOUNTS FROM LESS THAN A QUARTER
INCH IN NORTHERN HERKIMER COUNTY TO A LITTLE OVER TWO INCHES IN
THE LOWER HUDSON VALLEY OF NEW YORK AND THE LITCHFIELD HILLS OF
CONNECTICUT. OVER COOLER REGIONS SUCH AS THE HIGHER ELEVATIONS OF
THE CATSKILLS...BERKSHIRES...AND GREEN MOUNTAINS OF SOUTHERN
VERMONT A SUBSTANTIAL AMOUNT OF THIS PRECIPITATION IS FORECAST
TO COME AS SNOW. ACROSS OUR SOUTHERNMOST COUNTIES...EASTERN ULSTER
DUTCHESS...AND LITCHFIELD...MOST OF THE PRECIPITATION WILL
COME AS RAIN AND LOCALLY HEAVY AMOUNTS MAY AMOUNT TO ENOUGH TO
RESULT IN SOME MINOR FLOODING OF ROADS AND PARKING AREAS AND
CAUSE RISES OF SEVERAL FEET ON RIVERS AND STREAMS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...FLOOD WATCH UNTIL 9 AM EST THURSDAY FOR CTZ001-013.
NY...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR NYZ047-051-
054-058-063.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR NYZ039>043-
048>050-052-053-059>061-082>084.
FLOOD WATCH UNTIL 9 AM EST THURSDAY FOR NYZ064>066.
MA...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR MAZ001-025.
VT...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR VTZ013-014.
WINTER WEATHER ADVISORY UNTIL 6 AM EST THURSDAY FOR VTZ015.
&&
$$
SYNOPSIS...11
NEAR TERM...11/SNYDER
SHORT TERM...KL
LONG TERM...RCK
AVIATION...GJM
HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
304 AM CST THU DEC 8 2011
.DISCUSSION...
856 PM CST
SMALL UPDATES HAVE BEEN MADE FOR THE REMAINDER OF TONIGHTS
FORECAST...WITH ATTENTION TURNING TO THURSDAY NIGHTS SNOW
POTENTIAL.
VARIABLE CLOUD COVERAGE BY OVERNIGHT IS MAKING IT CHALLENGING ON
THE TEMPERATURE FORECAST. WITH AN INITIAL COLD FRONT CONTINUING
TO LOSE DEFINITION AS IT DRAPES INTO NORTHERN IL...LOW CLOUDS HAVE
DIMINISHED IN COVERAGE. SATELLITE TRENDS AND RUC SOUNDINGS ACROSS
NORTHEAST IL INDICATE TEMPORARY SCATTERED CLOUDS ARE LIKELY TO
CONTINUE TO PROPAGATE SOUTHEAST. CLOUDS ALONG THE MID-LEVEL
BAROCLINIC ZONE SEEN AT 700 MB ON THIS EVENINGS UPPER AIR ANALYSIS
WILL ALSO CONTINUE TO SLOWLY FILTER INTO THE AREA THROUGH THU
MORNING. SO WILL CONTINUE TO ADJUST SKY TRENDS...BUT ALL IN ALL
VARIABLE TO PARTLY CLOUDY WORDING IS PROBABLY THE BEST BET. EVEN
THOUGH THE HOURLY TREND WILL DEPEND HEAVILY ON HOW ANY CLOUDS
UNDULATE IN COVERAGE...LOW TEMPERATURES STILL LOOK ON TRACK.
SCATTERED MID-TEENS ARE FORECAST TOWARDS ROCKFORD AND
STERLING...WITH LOWER TO MID 20S TOWARDS THE LAKE AND INTO
NORTHWEST IN.
A LOOK AT THE LATEST GUIDANCE...08.00 NAM AND 07.21 SREF...AS WELL
AS UPSTREAM TRENDS ARE STARTING TO SUPPORT THE LIKELY SCENARIO
THAT A MINOR ACCUMULATING SNOW EVENT WILL BE SEEN IN THE FORECAST
AREA...ESPECIALLY THE SOUTHEAST QUARTER TO THIRD. THE UPPER AIR
ANALYSES THIS EVENING DEPICTED THE STRONG UPPER JET /OVER 120 KTS
AT UNR/ HEADING TOWARDS THE AREA WHICH WILL PROVIDE MORE
CONCENTRATED UPPER SUPPORT DURING TUE AFTERNOON AND NIGHT.
SATURATION AND QG FORCING WITH THE WAVE WILL NOT ARRIVE INTO
PARTS OF OUR AREA UNTIL THE NIGHT...LIKELY BY 03Z. THE NEW NAM
OUTPUT INDICATES MIXING RATIOS NEAR 2 G/KG ON THE FAVORED SURFACES
WHERE LIFT IS OCCURRING INTO THE FAR SOUTHEAST...AND THAT IS
NEARLY COINCIDENT WITH THE DENDRITIC GROWTH AREA. WHILE TOP-DOWN
METHODS ON THE NAM SOUNDINGS WARM SOME ON THE WAY DOWN...RATIOS
STILL LOOK TO BE ON THE HIGHER SIDE AS INDICATED BY EVEN THE
PRIOR NAM RUNS. THE SREF GUIDANCE HAS BECOME MORE FOCUSED ON ITS
SNOW PROBABILITIES...INDICATING A RIBBON ACROSS THE SOUTHEAST
/GIBSON CITY TO RENSSELAER/ WHERE OVER ONE INCH OF SNOW IS
FORECAST BY THE MEAN OF THE MEMBERS. EVEN THE PRIOR RUNS OF THESE
MODELS AND THE GFS...EC...AND NMM WRF...INDICATE THE FAR SOUTHERN
TIER OF COUNTIES TO SEE SNOW...AND COULD ENVISION BASED ON RATIOS
AND RECENTLY COOLED GROUND TEMPERATURES THAT ONE TO TWO INCH
ACCUMULATIONS ARE POSSIBLE. MINOR ACCUMULATIONS OF A COUPLE TENTHS
AS FAR NORTH AS CHICAGO CANNOT BE RULED OUT DEPENDING ON IF THE
ATMOSPHERE CAN SATURATE...AND LIGHT AMOUNTS ARE FORECAST THAT FAR
NORTH BY THE 18.00 NAM. WILL RE-ISSUE AN SPS TO HIGHLIGHT FOR NOW
AND BRIEF THE OVERNIGHT SHIFT.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* ISOLATED THREAT FOR -SN THURSDAY EVENING
SHEA
//DISCUSSION...UPDATED 06Z...
LIGHT WESTERLY WINDS WILL CONTINUE OVERNIGHT AS AN APPROACHING
NORTHERN HIGH PLAINS SYSTEM AND ANOTHER COLD FRONT DROPS SOUTHEAST
ACROSS WISCONSIN DURING THE DAY TODAY. THIS SYSTEM IS EXPECTED TO
PRODUCE SOME LIGHT SNOWFALL BUT THE ZONE OF BEST FORCING AT THIS
POINT LOOKS TO BE ALONG A NORTHERN MISSOURI...CENTRAL
IL...NORTHEAST INDINANA AXIS SO THREAT OF ANY PRECIPITATION AT
THE LOCAL TERMINALS QUITE SMALL.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN ALL ELEMENTS
SHEA
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...VFR INTO EVENING...SLGT CHC -SN PRODUCING MVFR CIGS
AND/OR VSBYS OVERNIGHT.
TUESDAY...MVFR CIGS POSSIBLE.
TRS
&&
.MARINE...
305 AM CST
A PROLONGED PERIOD OF GENERALLY WEST WINDS IS SETTING UP FOLLOWING
THE PASSAGE OF A COLD FRONT. ANOTHER SURGE OF COLD AIR ASSOCIATED
WITH A SECONDARY COLD FRONT WILL PUSH ACROSS THE LAKE LATER
TODAY...KEEPING WESTERLY WINDS IN THE 25 TO 30 KT INTO SATURDAY.
AN UPPER LEVEL TROUGH CROSSING THE GREAT LAKES REGION FRIDAY AND
FRIDAY NIGHT WILL BRING VERY COLD AIR ALOFT OVER LAKE MICHIGAN.
COMBINED WITH RELATIVELY WARMER LAKE SURFACE WATER...A VERY
UNSTABLE ENVIRONMENT WILL SET UP OVER THE LAKE...BRINGING A CHANCE
FOR WATERSPOUTS.
BY SATURDAY...WINDS WILL SHIFT SOUTHWESTERLY AS HIGH PRESSURE
BUILDS ACROSS THE OHIO VALLEY WHILE A WEAK LOW PRESSURE SYSTEM
TRACKS ACROSS THE UPPER GREAT LAKES. THE HIGH WILL BE FAR ENOUGH
TO THE SOUTH THAT WINDS WILL REMAIN AROUND 30 KT THROUGH THE
WEEKEND.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE BURNS HARBOR TO MICHIGAN
CITY IN UNTIL 10 AM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
205 AM CST THU DEC 8 2011
.DISCUSSION...
856 PM CST
SMALL UPDATES HAVE BEEN MADE FOR THE REMAINDER OF TONIGHTS
FORECAST...WITH ATTENTION TURNING TO THURSDAY NIGHTS SNOW
POTENTIAL.
VARIABLE CLOUD COVERAGE BY OVERNIGHT IS MAKING IT CHALLENGING ON
THE TEMPERATURE FORECAST. WITH AN INITIAL COLD FRONT CONTINUING
TO LOSE DEFINITION AS IT DRAPES INTO NORTHERN IL...LOW CLOUDS HAVE
DIMINISHED IN COVERAGE. SATELLITE TRENDS AND RUC SOUNDINGS ACROSS
NORTHEAST IL INDICATE TEMPORARY SCATTERED CLOUDS ARE LIKELY TO
CONTINUE TO PROPAGATE SOUTHEAST. CLOUDS ALONG THE MID-LEVEL
BAROCLINIC ZONE SEEN AT 700 MB ON THIS EVENINGS UPPER AIR ANALYSIS
WILL ALSO CONTINUE TO SLOWLY FILTER INTO THE AREA THROUGH THU
MORNING. SO WILL CONTINUE TO ADJUST SKY TRENDS...BUT ALL IN ALL
VARIABLE TO PARTLY CLOUDY WORDING IS PROBABLY THE BEST BET. EVEN
THOUGH THE HOURLY TREND WILL DEPEND HEAVILY ON HOW ANY CLOUDS
UNDULATE IN COVERAGE...LOW TEMPERATURES STILL LOOK ON TRACK.
SCATTERED MID-TEENS ARE FORECAST TOWARDS ROCKFORD AND
STERLING...WITH LOWER TO MID 20S TOWARDS THE LAKE AND INTO
NORTHWEST IN.
A LOOK AT THE LATEST GUIDANCE...08.00 NAM AND 07.21 SREF...AS WELL
AS UPSTREAM TRENDS ARE STARTING TO SUPPORT THE LIKELY SCENARIO
THAT A MINOR ACCUMULATING SNOW EVENT WILL BE SEEN IN THE FORECAST
AREA...ESPECIALLY THE SOUTHEAST QUARTER TO THIRD. THE UPPER AIR
ANALYSES THIS EVENING DEPICTED THE STRONG UPPER JET /OVER 120 KTS
AT UNR/ HEADING TOWARDS THE AREA WHICH WILL PROVIDE MORE
CONCENTRATED UPPER SUPPORT DURING TUE AFTERNOON AND NIGHT.
SATURATION AND QG FORCING WITH THE WAVE WILL NOT ARRIVE INTO
PARTS OF OUR AREA UNTIL THE NIGHT...LIKELY BY 03Z. THE NEW NAM
OUTPUT INDICATES MIXING RATIOS NEAR 2 G/KG ON THE FAVORED SURFACES
WHERE LIFT IS OCCURRING INTO THE FAR SOUTHEAST...AND THAT IS
NEARLY COINCIDENT WITH THE DENDRITIC GROWTH AREA. WHILE TOP-DOWN
METHODS ON THE NAM SOUNDINGS WARM SOME ON THE WAY DOWN...RATIOS
STILL LOOK TO BE ON THE HIGHER SIDE AS INDICATED BY EVEN THE
PRIOR NAM RUNS. THE SREF GUIDANCE HAS BECOME MORE FOCUSED ON ITS
SNOW PROBABILITIES...INDICATING A RIBBON ACROSS THE SOUTHEAST
/GIBSON CITY TO RENSSELAER/ WHERE OVER ONE INCH OF SNOW IS
FORECAST BY THE MEAN OF THE MEMBERS. EVEN THE PRIOR RUNS OF THESE
MODELS AND THE GFS...EC...AND NMM WRF...INDICATE THE FAR SOUTHERN
TIER OF COUNTIES TO SEE SNOW...AND COULD ENVISION BASED ON RATIOS
AND RECENTLY COOLED GROUND TEMPERATURES THAT ONE TO TWO INCH
ACCUMULATIONS ARE POSSIBLE. MINOR ACCUMULATIONS OF A COUPLE TENTHS
AS FAR NORTH AS CHICAGO CANNOT BE RULED OUT DEPENDING ON IF THE
ATMOSPHERE CAN SATURATE...AND LIGHT AMOUNTS ARE FORECAST THAT FAR
NORTH BY THE 18.00 NAM. WILL RE-ISSUE AN SPS TO HIGHLIGHT FOR NOW
AND BRIEF THE OVERNIGHT SHIFT.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* ISOLATED THREAT FOR -SN THURSDAY EVENING
SHEA
//DISCUSSION...UPDATED 06Z...
LIGHT WESTERLY WINDS WILL CONTINUE OVERNIGHT AS AN APPROACHING
NORTHERN HIGH PLAINS SYSTEM AND ANOTHER COLD FRONT DROPS SOUTHEAST
ACROSS WISCONSIN DURING THE DAY TODAY. THIS SYSTEM IS EXPECTED TO
PRODUCE SOME LIGHT SNOWFALL BUT THE ZONE OF BEST FORCING AT THIS
POINT LOOKS TO BE ALONG A NORTHERN MISSOURI...CENTRAL
IL...NORTHEAST INDINANA AXIS SO THREAT OF ANY PRECIPITATION AT
THE LOCAL TERMINALS QUITE SMALL.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN ALL ELEMENTS
SHEA
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...VFR INTO EVENING...SLGT CHC -SN PRODUCING MVFR CIGS
AND/OR VSBYS OVERNIGHT.
TUESDAY...MVFR CIGS POSSIBLE.
TRS
&&
.MARINE...
157 PM CST
A COLD FRONT MOVING ACROSS LAKE SUPERIOR AND WISCONSIN THIS
AFTERNOON WILL MOVE ACROSS LAKE MICHIGAN LATER THIS AFTERNOON AND
EVENING. THIS WILL HELP KEEP THE WINDS AROUND 25 TO 30 KT TONIGHT AS
THE WINDS BECOME NORTHWESTERLY. A PROLONGED PERIOD OF BRISK WEST TO
NORTHWESTERLY WINDS IS EXPECTED INTO SATURDAY AS HIGH PRESSURE
MOVING FROM THE PLAINS EASTWARD ACROSS THE MID MISSISSIPPI
VALLEY...WILL CONTINUE TO PRODUCE A DECENT PRESSURE GRADIENT ACROSS
THE GREAT LAKES.
LATER SATURDAY THE WINDS LOOK TO SWITCH OUT OF THE SOUTHWEST AND
INCREASE TO AROUND 30 KT AGAIN AS THE SURFACE HIGH SHIFTS ACROSS THE
OHIO VALLEY AND ANOTHER AREA OF LOW PRESSURE MOVES ACROSS THE
PRAIRIE PROVIDENCES OF CANADA. IT APPEARS THAT THESE SOUTHWESTERLY
WINDS WILL CONTINUE INTO EARLY NEXT WEEK AS THE SURFACE HIGH
CONTINUES TO DOMINATE ACROSS EASTERN CONUS. THERE COULD EVEN BE A
PERIOD OF LOW END GALE FORCE WINDS DURING THIS PERIOD.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO BURNS HARBOR UNTIL
10 PM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN UNTIL 10 AM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1227 AM CST THU DEC 8 2011
.DISCUSSION...
856 PM CST
SMALL UPDATES HAVE BEEN MADE FOR THE REMAINDER OF TONIGHTS
FORECAST...WITH ATTENTION TURNING TO THURSDAY NIGHTS SNOW
POTENTIAL.
VARIABLE CLOUD COVERAGE BY OVERNIGHT IS MAKING IT CHALLENGING ON
THE TEMPERATURE FORECAST. WITH AN INITIAL COLD FRONT CONTINUING
TO LOSE DEFINITION AS IT DRAPES INTO NORTHERN IL...LOW CLOUDS HAVE
DIMINISHED IN COVERAGE. SATELLITE TRENDS AND RUC SOUNDINGS ACROSS
NORTHEAST IL INDICATE TEMPORARY SCATTERED CLOUDS ARE LIKELY TO
CONTINUE TO PROPAGATE SOUTHEAST. CLOUDS ALONG THE MID-LEVEL
BAROCLINIC ZONE SEEN AT 700 MB ON THIS EVENINGS UPPER AIR ANALYSIS
WILL ALSO CONTINUE TO SLOWLY FILTER INTO THE AREA THROUGH THU
MORNING. SO WILL CONTINUE TO ADJUST SKY TRENDS...BUT ALL IN ALL
VARIABLE TO PARTLY CLOUDY WORDING IS PROBABLY THE BEST BET. EVEN
THOUGH THE HOURLY TREND WILL DEPEND HEAVILY ON HOW ANY CLOUDS
UNDULATE IN COVERAGE...LOW TEMPERATURES STILL LOOK ON TRACK.
SCATTERED MID-TEENS ARE FORECAST TOWARDS ROCKFORD AND
STERLING...WITH LOWER TO MID 20S TOWARDS THE LAKE AND INTO
NORTHWEST IN.
A LOOK AT THE LATEST GUIDANCE...08.00 NAM AND 07.21 SREF...AS WELL
AS UPSTREAM TRENDS ARE STARTING TO SUPPORT THE LIKELY SCENARIO
THAT A MINOR ACCUMULATING SNOW EVENT WILL BE SEEN IN THE FORECAST
AREA...ESPECIALLY THE SOUTHEAST QUARTER TO THIRD. THE UPPER AIR
ANALYSES THIS EVENING DEPICTED THE STRONG UPPER JET /OVER 120 KTS
AT UNR/ HEADING TOWARDS THE AREA WHICH WILL PROVIDE MORE
CONCENTRATED UPPER SUPPORT DURING TUE AFTERNOON AND NIGHT.
SATURATION AND QG FORCING WITH THE WAVE WILL NOT ARRIVE INTO
PARTS OF OUR AREA UNTIL THE NIGHT...LIKELY BY 03Z. THE NEW NAM
OUTPUT INDICATES MIXING RATIOS NEAR 2 G/KG ON THE FAVORED SURFACES
WHERE LIFT IS OCCURRING INTO THE FAR SOUTHEAST...AND THAT IS
NEARLY COINCIDENT WITH THE DENDRITIC GROWTH AREA. WHILE TOP-DOWN
METHODS ON THE NAM SOUNDINGS WARM SOME ON THE WAY DOWN...RATIOS
STILL LOOK TO BE ON THE HIGHER SIDE AS INDICATED BY EVEN THE
PRIOR NAM RUNS. THE SREF GUIDANCE HAS BECOME MORE FOCUSED ON ITS
SNOW PROBABILITIES...INDICATING A RIBBON ACROSS THE SOUTHEAST
/GIBSON CITY TO RENSSELAER/ WHERE OVER ONE INCH OF SNOW IS
FORECAST BY THE MEAN OF THE MEMBERS. EVEN THE PRIOR RUNS OF THESE
MODELS AND THE GFS...EC...AND NMM WRF...INDICATE THE FAR SOUTHERN
TIER OF COUNTIES TO SEE SNOW...AND COULD ENVISION BASED ON RATIOS
AND RECENTLY COOLED GROUND TEMPERATURES THAT ONE TO TWO INCH
ACCUMULATIONS ARE POSSIBLE. MINOR ACCUMULATIONS OF A COUPLE TENTHS
AS FAR NORTH AS CHICAGO CANNOT BE RULED OUT DEPENDING ON IF THE
ATMOSPHERE CAN SATURATE...AND LIGHT AMOUNTS ARE FORECAST THAT FAR
NORTH BY THE 18.00 NAM. WILL RE-ISSUE AN SPS TO HIGHLIGHT FOR NOW
AND BRIEF THE OVERNIGHT SHIFT.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* ISOLATED THREAT FOR -SN THURSDAY EVENING
SHEA
//DISCUSSION...UPDATED 06Z...
LIGHT WESTERLY WINDS WILL CONTINUE OVERNIGHT AS AN APPROACHING
NORTHERN HIGH PLAINS SYSTEM AND ANOTHER COLD FRONT DROPS SOUTHEAST
ACROSS WISCONSIN DURING THE DAY TODAY. THIS SYSTEM IS EXPECTED TO
PRODUCE SOME LIGHT SNOWFALL BUT THE ZONE OF BEST FORCING AT THIS
POINT LOOKS TO BE ALONG A NORTHERN MISSOURI...CENTRAL
IL...NORTHEAST INDINANA AXIS SO THREAT OF ANY PRECIPITATION AT
THE LOCAL TERMINALS QUITE SMALL.
SHEA
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN ALL ELEMENTS
SHEA
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
*
FRIDAY...VFR.
SATURDAY...VFR.
SUNDAY...VFR.
MONDAY...VFR INTO EVENING...SLGT CHC -SN PRODUCING MVFR CIGS
AND/OR VSBYS OVERNIGHT.
TUESDAY...MVFR CIGS POSSIBLE.
*
TRS
&&
.MARINE...
157 PM CST
A COLD FRONT MOVING ACROSS LAKE SUPERIOR AND WISCONSIN THIS
AFTERNOON WILL MOVE ACROSS LAKE MICHIGAN LATER THIS AFTERNOON AND
EVENING. THIS WILL HELP KEEP THE WINDS AROUND 25 TO 30 KT TONIGHT AS
THE WINDS BECOME NORTHWESTERLY. A PROLONGED PERIOD OF BRISK WEST TO
NORTHWESTERLY WINDS IS EXPECTED INTO SATURDAY AS HIGH PRESSURE
MOVING FROM THE PLAINS EASTWARD ACROSS THE MID MISSISSIPPI
VALLEY...WILL CONTINUE TO PRODUCE A DECENT PRESSURE GRADIENT ACROSS
THE GREAT LAKES.
LATER SATURDAY THE WINDS LOOK TO SWITCH OUT OF THE SOUTHWEST AND
INCREASE TO AROUND 30 KT AGAIN AS THE SURFACE HIGH SHIFTS ACROSS THE
OHIO VALLEY AND ANOTHER AREA OF LOW PRESSURE MOVES ACROSS THE
PRAIRIE PROVIDENCES OF CANADA. IT APPEARS THAT THESE SOUTHWESTERLY
WINDS WILL CONTINUE INTO EARLY NEXT WEEK AS THE SURFACE HIGH
CONTINUES TO DOMINATE ACROSS EASTERN CONUS. THERE COULD EVEN BE A
PERIOD OF LOW END GALE FORCE WINDS DURING THIS PERIOD.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO BURNS HARBOR UNTIL
10 PM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN UNTIL 10 AM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
347 AM CST THU DEC 8 2011
.DISCUSSION...
TODAY AND TONIGHT...AN UPPER LEVEL TROUGH OVER THE NORTHERN HIGH
PLAINS WILL DIG SOUTHEAST TODAY ACROSS THE CENTRAL PLAINS. THE
STRONGER MID-LEVEL FRONTOGENETICAL FORCING AHEAD OF THE H5 TROUGH WILL
SHIFT SOUTHEAST ACROSS SD INTO EASTERN NE...IA AND NORTHERN MO. A
BAND OF WEAKER MID-LEVEL FRONTOGENETICAL FORCING WILL EXTEND
SOUTHWEST INTO NORTHEAST KS THIS AFTERNOON AND INTO THE EVENING
HOURS BEFORE SHIFTING EAST. THE GFS MODEL FORECAST THE THE
STRONGEST ASCENT AND ENOUGH MOISTURE FOR 1 TO 2 INCHES OF SNOWFALL
ACROSS THE NORTHERN COUNTIES OF THE CWA. THE NAM AND ECMWF ARE NOT
AS AMPLIFIED AND ONLY SHOW ABOUT HALF OF AN INCH TO ONE INCH OF
SNOW ACROSS THE NORTHEAST COUNTIES OF THE CWA. THERE MAY ONLY BE
TRACE AMOUNTS OF SNOWFALL ACROSS THE SOUTHERN COUNTIES OF THE CWA LATE
THIS AFTERNOON AND THIS EVENING. ONCE THE H5 TROUGH AXIS SHIFTS
SOUTHEAST OF THE PLAINS TONIGHT...THE SNOW SHOULD END FROM
NORTHWEST TO SOUTHEAST ACROSS THE CWA DURING THE LATE EVENING
HOURS. A SECOND H5 TROUGH WILL DIG SOUTHWARD ACROSS THE EASTERN
PLAINS THEN MOVE SOUTHEAST ACROSS IA INTO NORTHERN MO DURING THE
EARLY MORNING HOURS OF FRIDAY. ATTM...THE STRONGER FORCING WILL
REMAIN NORTH AND NORTHEAST OF THE CWA...THUS ANY LIGHT SNOW SHOULD
MOVE SOUTHEAST FROM EASTERN NE...SOUTHEAST ACROSS IA INTO NORTHERN
MO THROUGH THE MORNING HOURS OF FRIDAY.
HIGHS TODAY WILL RANGE FROM THE LOWER TO MID 30S ACROSS THE NORTHERN
COUNTIES WHERE CLOUD COVER WILL INCREASE DURING THE MID MORNING
HOURS TO THE THE UPPER 30S TO AROUND 40S ACROSS EAST CENTRAL KS.
FRIDAY...A SURFACE RIDGE OF HIGH PRESSURE WILL BUILD SOUTHWARD
ACROSS EASTERN KS. LOW-LEVEL CAA WILL KEEP HIGHS IN THE LOWER TO MID
30S...EVEN THOUGH SKIES WILL CLEAR DURING THE AFTERNOON HOURS.
SATURDAY THROUGH MONDAY...THE FLOW ALOFT WILL BECOME ZONAL.
SOUTHWEST TO SOUTHERLY SURFACE WINDS WILL ALLOW HIGH TEMPERATURES TO
WARM INTO THE LOWER 40S ON SATURDAY WITH MID TO UPPER 40S SUNDAY AND
MONDAY.
MONDAY NIGHT AND TUESDAY...AN UPPER LEVEL TROUGH WILL DIG SOUTHWARD
ACROSS THE WESTERN CONUS INTO THE DESERT SOUTHWEST. A WEAK H5 TROUGH
WILL MOVE EAST ACROSS THE NORTHERN PLAINS AND WILL CAUSE A WEAK COLD
FRONT TO PUSH SOUTHEAST ACROSS THE CWA. THE LOW-LEVELS OF THE
ATMOSPHERE LOOK TOO DRY FOR MEASURABLE PRECIPITATION TO DEVELOP ALONG OR
BEHIND THE FRONT. HIGHS ON TUESDAY WILL COOL SLIGHTLY INTO THE
UPPER 30S TO LOWER 40S.
TUESDAY NIGHT AND WEDNESDAY...THE GFS AND ECMWF MODEL SOLUTIONS
DIFFER IN THE MOVEMENT OF THE UPPER LOW THAT EJECTS OUT EITHER EAST
OR NORTHEAST INTO THE SOUTHERN AND CENTRAL PLAINS. THE GFS SHOWS THE
UPPER LOW MOVING DUE EAST ACROSS WEST TX INTO SOUTHERN OK. THE
ECMWF...SHOWS MORE OF AN OPEN WAVE LIFTING TO THE NORTHEAST ACROSS
KS AND NE. IF THE GFS WERE TO VERIFY THE CWA WOULD REMAIN DRY BUT
COLDER. IF THE ECMWF WERE TO VERIFY THE RAIN AND PERHAPS A FEW
ISOLATED THUNDERSTORMS WILL DEVELOP AS DEEPER MOISTURE AND WARMER
AIR ADVECT NORTHWARD ACROSS THE STATE TUESDAY NIGHT INTO
WEDNESDAY. ATTM...I WILL KEEP AT LEAST A CHANCE FOR RAIN ACROSS
THE CWA ON WEDNESDAY WITH HIGHS IN THE MID TO UPPER 40S...MAY BE
EVEN LOWER TO MID 50S IF THE ECMWF SOLUTION VERIFIES.
GARGAN
&&
.AVIATION...
THE LATEST RUC AND NAM FORECAST SOUNDINGS DO NOT COOL SFC TEMPS OFF
AS MUCH AS EARLIER RUNS. BECAUSE OF THIS THEY ARE LESS AGGRESSIVE IN
SATURATING THE BOUNDARY LAYER. SINCE CONDITIONS ARE GOOD FOR
RADIATIONAL COOLING AND THE POTENTIAL FOR SOME GROUND FOG EXISTS...
WILL KEEP A MENTION FOR TOP AND MHK WHERE THE KS RIVER COULD PROVIDE
ADDITIONAL BOUNDARY LAYER MOISTURE.
MODELS CONTINUE TO SHOW A WEAK SHORTWAVE MOVING ACROSS THIS
AFTERNOON AND EVENING. FORCING FOR PRECIP IS NOT OVERWHELMING.
HOWEVER IT LOOKS LIKE THERE COULD BE A 3 TO 4 HOUR WINDOW FOR SOME
LIGHT SNOW...ESPECIALLY ACROSS NORTHEAST KS. WITH GOOD CONSENSUS IN
MODEL QPF...HAVE SOME CONFIDENCE IN LIGHT SNOW DEVELOPING WITH
INTENSITY BEING FAIRLY LIGHT AND LITTLE ACCUMULATION. THEREFORE ONLY
TAKE THE TAFS TO MVFR IN SPITE OF THE MET MOS SHOWING IFR CONDITIONS.
WOLTERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
303 AM CST THU DEC 8 2011
.DISCUSSION...
DAYS 1-2...
THE MAIN FORECAST FOCUS WILL BE ON THE CHANCE FOR LIGHT PRECIP EARLY
IN THE PERIOD.
WV IMAGERY AND 00Z UPPER AIR ANALYSIS INDICATES AN UPPER LEVEL
SHORTWAVE DIPPING SOUTHEAST OUT OF CANADA INTO THE NORTHERN ROCKIES.
A POOL OF H7 MOISTURE IS ACCOMPANYING THE SHORTWAVE EXTENDING FROM
EASTERN MONTANA EAST AND SOUTHEAST INTO THE NORTHERN PLAINS. A COLD
FRONT IS PUSHING SOUTH ACROSS SOUTH DAKOTA NEARING NORTHERN NEBRASKA.
SHORT RANGE MODELS INDICATE THE UPPER LEVEL SHORTWAVE SWINGING
SOUTHEAST OUT OF THE NORTHERN ROCKIES INTO THE NORTHERN PLAINS
TODAY. IT WILL HELP USHER A COLD FRONT SOUTH INTO WESTERN KANSAS
BY THIS AFTERNOON BRINGING WITH IT MUCH COOLER AIR INTO THE REGION.
VERY LITTLE IN THE WAY OF PRECIP IS EXPECTED WITH A LACK OF MOISTURE
IN THE LOWER LEVELS. HOWEVER, AREAS OF LIGHT FREEZING DRIZZLE
OR SNOW CANNOT BE COMPLETELY RULED OUT THIS AFTERNOON ACROSS
NORTHERN PORTIONS OF THE CWA AS TEMPERATURES COOL DOWN QUITE A
BIT NEARLY SATURATING THE LOWER LEVELS. FLURRIES ARE POSSIBLE THIS
EVENING WITH MODEL SOUNDINGS SHOWING BELOW FREEZING TEMPERATURES
AT ALL LEVELS. OTHERWISE, FAIRLY DRY CONDITIONS ARE EXPECTED INTO
THE WEEKEND AS UPPER LEVEL RIDGING BUILDS INTO THE INTERMOUNTAIN
WEST FRIDAY.
TEMPERATURES WILL BE BELOW NORMAL TODAY AS COLDER AIR BEGINS TO
FILTER SOUTH INTO WESTERN KANSAS BY EARLY THIS AFTERNOON BEHIND A
COLD FRONT MOVING ACROSS THE AREA. ALL MODELS SHOW H85 TEMPERATURES
DROPPING TO NEAR TO JUST BELOW 0C ACROSS MUCH OF THE CWA BY MID
DAY. EXPECT HIGHS ONLY UP INTO THE 30S(F) BY THIS AFTERNOON WITH A
FEW LOWER 40S(F) POSSIBLE IN OUR SOUTHEAST, ESPECIALLY WITH
INCREASING CLOUDS. TEMPERATURES WILL REMAIN FAIRLY COLD FRIDAY AS
SURFACE HIGH PRESSURE DRIFTS EAST ACROSS THE CENTRAL PLAINS
KEEPING THE SAME GENERAL AIR MASS IN PLACE ACROSS WESTERN KANSAS.
SHOULD SEE FAIRLY SIMILAR HIGHS ON FRIDAY EVEN WITH FEWER CLOUDS
EXPECTED.
DAYS 3-7...
SPLIT UPPER LEVEL FLOW CONTINUES INTO THE WEEKEND OVER THE PLAINS. A
STRONG UPPER LEVEL SHORTWAVE TROUGH DIGS INTO THE PACIFIC NORTHWEST
ON SUNDAY. BY MONDAY THE NEW ECMWF HAS A CUTOFF UPPER LOW JUST WEST
OF THE SOUTHERN CALIFORNIA COASTLINE AND THE GFS IS FASTER WITH A
MORE OPEN UPPER LOW OVER SOUTHERN CALIFORNIA. ON TUESDAY A NORTHERN
BRANCH WAVE MOVES ACROSS THE UPPER MIDWEST WITH THE GFS CONTINUES TO
PUSH A CLOSED UPPER LOW INTO NEW MEXICO WHILE THE SLOWER ECMWF AND
GEM HAVE A TROUGH MORE WEST INTO SOUTHERN CALIFORNIA. FOR WEDNESDAY
THE GFS CONTINUES A FASTER AND MORE SOUTHERN TRACK INTO NORTHEASTERN
TEXAS WHILE THE ECMWF HAS A NEGATIVELY TILTED OPEN SHORTWAVE TROUGH
LIFTING NORTHEASTWARD INTO NEBRASKA. THE NEW CANADIAN HAS THE UPPER
LOW ON SATURDAY EVENING JUST INTO SOUTHWEST KANSAS AND IS MORE
NEUTRALLY TILTED.
WHAT THIS MEANS ANY SENSIBLE WEATHER WILL HOLD OFF UNTIL THE UPPER
LEVEL LOW LIFTS OUT INTO THE PLAINS ON WEDNESDAY. LOTS OF MODEL
DIFFERENCES WILL MAKE THIS FORECAST INTO THE MIDDLE OF NEXT WEEK A
VERY LOW CONFIDENCE FORECAST WITH THE TRACK OF THE UPPER LOW. THE
ECMWF AND GFS HAVE RAIN AND THE CANADIAN HAS RAIN OR SNOW. FOR NOW
WILL HOLD ONTO CONSENSUS MODEL THAT HAS MOSTLY RAIN AND WARMER TEMPS.
IN GENERAL A LEE LOW WILL BRING WARMER SOUTH TO SOUTHWEST SURFACE
WINDS INTO THE WEEKEND WITH HIGHS INTO THE 40S. CANADIAN HIGH
PRESSURE MOVES INTO THE PLAINS ON MONDAY AND TUESDAY WITH SLIGHTLY
COOLER HIGH TEMPERATURES. THEN FOR WEDNESDAY THE ECMWF HAS THE UPPER
LOW MUCH MORE NORTH AND BRINGS IN HIGHER DEWPOINTS AND QPF TO
WESTERN KANSAS. FOR NOW WILL CONTINUE WITH CONSENSUS POPS AND TEMPS
WHICH FAVOR HIGHEST POPS SOUTH AND EAST FA AND HIGHS IN THE 50S.
OVERNIGHT LOWS LOOK TO BE IN THE 20S WEST AND NORTHWEST FA TO THE
30S IN THE SOUTH AND SOUTHEAST.
&&
.AVIATION...
FOR THE 06Z TAF ISSUANCE...
THIS EVENING`S KDDC UPPER AIR SOUNDING CONTINUES TO SHOW DEEP DRY
LOWER AND MIDDLE TROPOSPHERIC LAYERS WITH DEEP NORTHWEST FLOW ALOFT.
THE LATEST RAPID REFRESH RUC MODEL IS DELAYING THE DEVELOPMENT OF
MVFR STRATUS CONSIDERABLY LATER INTO THE LATE AFTERNOON ACROSS
NORTHWEST KANSAS. CONSIDERING THE CURRENT LACK OF LOW CLOUD
DEVELOPMENT ACROSS THE NORTHERN HIGH PLAINS REGION, WE CAN`T FIND A
GOOD REASON TO DISCOUNT THIS MODEL SHIFT AND HAVE DELAYED MVFR
CEILINGS BY ABOUT 8 HOURS IN THE TAF TIME FRAME.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 37 17 37 17 / 10 10 0 0
GCK 33 15 33 15 / 10 10 0 0
EHA 35 17 32 20 / 10 10 0 0
LBL 37 18 37 18 / 10 10 0 0
HYS 32 15 30 15 / 40 20 0 0
P28 42 20 38 18 / 10 10 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN32/06/06
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1148 PM CST WED DEC 7 2011
.UPDATE...
&&
.PREV DISCUSSION... /ISSUED 546 PM CST WED DEC 7 2011/
UPDATE...
AVIATION /FOR THE 06Z TAF ISSUANCE/
THIS EVENING`S KDDC UPPER AIR SOUNDING CONTINUES TO SHOW DEEP DRY
LOWER AND MIDDLE TROPOSPHERIC LAYERS WITH DEEP NORTHWEST FLOW ALOFT.
THE LATEST RAPID REFRESH RUC MODEL IS DELAYING THE DEVELOPMENT OF
MVFR STRATUS CONSIDERABLY LATER INTO THE LATE AFTERNOON ACROSS
NORTHWEST KANSAS. CONSIDERING THE CURRENT LACK OF LOW CLOUD
DEVELOPMENT ACROSS THE NORTHERN HIGH PLAINS REGION, WE CAN`T FIND A
GOOD REASON TO DISCOUNT THIS MODEL SHIFT AND HAVE DELAYED MVFR
CEILINGS BY ABOUT 8 HOURS IN THE TAF TIMEFRAME.
PREV DISCUSSION... /ISSUED 341 PM CST WED DEC 7 2011/
SYNOPSIS...
ON THE SYNOPTIC SCALE TODAY...AN UPPER LOW WAS CENTERED OVER THE
SOUTHERN APPALACHIANS WITH WIDESPREAD PRECIPITATION OVER MUCH OF THE
MID ATLANTIC AND INTERIOR NORTHEAST CONUS. SHORTWAVE RIDGING WAS
INFLUENCING SENSIBLE WEATHER OVER THE CENTRAL CONUS WITH DOWNSLOPE
WARMING OCCURRING OVER THE CENTRAL PLAINS. AFTERNOON TEMPERATURES
ROSE TO THE MID AND UPPER 40S OVER SOUTHWEST KANSAS IN THE DOWNSLOPE
NORTHWEST WINDS. ANOTHER SHORTWAVE TROUGH WAS LOCATED OVER THE
ALBERTA ROCKIES AND CONTINUED TO MOVE SOUTHEAST AROUND THE SOUTHEAST
SIDE OF A LARGE LONGWAVE CYCLONE THAT WAS CENTERED OVER WESTERN
HUDSON BAY. -UMSCHEID
DISCUSSION...
DAYS 1-2...
THE SHORTWAVE TROUGH OVER SOUTHERN ALBERTA WILL REACH WYOMING BY 12Z
THURSDAY...AND A BAND OF MID LEVEL FRONTOGENESIS AND ENHANCED RH
WILL DEVELOP AHEAD OF THE DISTURBANCE OVER WESTERN NEBRASKA. THIS
WILL SHIFT SOUTHEAST THROUGH THE DAY THURSDAY ACROSS SOUTHERN
NEBRASKA/NORTHERN KANSAS. IN THE LOWER TROPOSPHERE (900 TO
800MB)...LOW LEVEL RH WILL INCREASE TO THE POINT THAT LOW STRATUS
WILL FORM BY LATE MORNING BEHIND THE DEVELOPING SURFACE COLD FRONT.
A FETCH OF NORTHEAST WINDS IN THIS LAYER WILL DEVELOP WHICH WILL
HAVE UPSLOPE COMPONENT FROM SOUTHEAST NEBRASKA/NORTHEAST KANSAS TO
SOUTHWEST KANSAS. A WEAK CYCLONIC CIRCULATION WILL DEVELOP OVER
NORTHWEST OKLAHOMA AROUND 850MB...WHICH WILL YIELD SOME WEAK
FRONTOGENESIS ACROSS THE SOUTHERN DDC FA BY LATE IN THE DAY/EARLY
EVENING THURSDAY. THE SATURATION OF THE 900-800MB LAYER WILL STILL
BE PRETTY FAR NORTH OF THE BEST FRONTOGENESIS IN THIS LAYER...SO
THIS DISCONNECT BETWEEN THE SATURATION AND LIFT WILL LIMIT
WIDESPREAD DRIZZLE FORMATION. NEVERTHELESS...THE UPSLOPE ALONE ON
THE NORTHEAST WINDS MAY BE ENOUGH TO GENERATE AT LEAST PATCHY
FREEZING DRIZZLE.
THE DEPTH OF THE SATURATED LAYER DURING THE DAY AND EARLY EVENING
TOMORROW IS EXPECTED EXTEND UP TO ABOUT 800 OR 750MB...WHERE
TEMPERATURES WILL BE -4 OR -5C...SO THE PRECIPITATION TYPE SHOULD BE
FREEZING DRIZZLE INSTEAD OF SNOW FLURRIES. A DEEPER MOIST LAYER IS
EXPECTED FARTHER NORTH LATE IN THE DAY (SAY NORTH OF HIGHWAY
4)...AND THE PROBABILITY OF SNOW FLURRIES IS GREATER...SO WILL CARRY
FREEZING DRIZZLE OR SNOW FLURRIES UP THERE LATE IN THE DAY/EARLY
EVENING. THE EVENT...SHOULD IT EVEN UNFOLD...WILL END BY LATE
EVENING/MIDNIGHT TIME FRAME AS THE SHORTWAVE TROUGH RESPONSIBLE
QUICKLY EXITS THE CENTRAL PLAINS.
THE REMAINDER OF THE FORECAST WILL BE DRY THROUGH FRIDAY AS
SUBSIDENCE PREVAILS AND SKIES CLEAR. VERY COLD AIR IS NOT EXPECTED
AFTER THIS WAVE MOVES BY AS MID LEVEL DOWNSLOPE WILL DEVELOP ONCE
AGAIN IN THE 850-700MB LAYER...WHICH WILL SUPPORT SURFACE HIGHS IN
THE UPPER 30S TO LOWER 40S. -UMSCHEID
DAYS 3-7...
THE EXTENDED PERIOD BEGINS 00Z SATURDAY. HAVE STUCK WITH THE
INITIALIZED CR ALLBLEND GRIDS AS THIS WAS THE CONSENSUS ESTABLISHED
WITH SURROUNDING WFOS. THERE IS A BIT OF UNCERTAINTY NEXT WEDNESDAY
REGARDING POPS. THIS IS VERY FAR IN THE EXTENDED PERIOD AND IS A LOW
CONFIDENCE FORECAST AS THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE
12Z GFS AND 12Z ECMWF IN ADDITION BETWEEN THE 00Z ECMWF AND 12Z
ECMWF.
SATURDAY/SUNDAY:
KANSAS WILL BE IN SPLIT FLOW NEXT WEEKEND. INCREASING WESTERLY FLOW
IN ASSOCIATION WITH THE SOUTHERN BRANCH JET WILL RESULT IN SURFACE
LEE TROUGHING ACROSS EASTERN COLORADO. 850 HPA TEMPERATURES ARE
FORECAST IN THE 2 TO 3 DEG C RANGE WHICH SUPPORT TEMPERATURES IN THE
40S DEG F ACROSS THE REGION...WHICH IS NEAR CLIMATOLOGY. THE
FORECAST WILL REMAIN DRY WITH BREEZY SOUTHERLY TO SOUTHWESTERLY
WINDS. LOWS WILL BE NEAR NORMAL TOO...PARTICULARLY SUNDAY WITH 20S
DEG F PREVAILING FOR SW KANSAS.
MONDAY:
AN UPPER LEVEL SHORTWAVE TROUGH IN ASSOCIATION WITH THE NORTHERN
BRANCH JET WILL USHER IN A COLD FRONT MONDAY. THIS FRONT DOESN`T
LOOK VERY STRONG AND IS EXPECTED TO BE DRY. TEMPERATURES WILL COOL
DOWN ABOUT 5 OR SO DEGREES MONDAY. ANOTHER IMPACT FROM THE FRONT
WILL BE INCREASING CLOUD COVER, MAINLY IN THE FORM OF MID TO HIGH
LEVEL CLOUDS.
TUESDAY:
WE WILL BE IN BETWEEN WEATHER SYSTEMS. THE SOUTHERN BRANCH JET
WILL INTENSIFY RESULTING IN THE FORMATION OF A WEAK LEE SURFACE
TROUGH AND SLIGHT WARMER TEMPERATURES (WARM AIR ADVECTION PATTERN).
WE COULD SEE SOME HIGH LEVEL CLOUDS CONTINUING TUESDAY AS WELL AS
MID TO UPPER LEVEL FLOW INCREASES FROM THE SOUTHWEST IN ASSOCIATION
WITH THE APPROACHING SHORTWAVE TROUGH/JET. -SUGDEN
WEDNESDAY:
THERE ARE LARGE DIFFERENCES BETWEEN THE GFS AND ECMWF AT THIS POINT.
THEY BOTH SHOW AN UPPER LEVEL SYSTEM MOVING ACROSS THE REGION WITH
RETURN FLOW SETTING UP AND HIGHER DEWPOINTS ADVECTING IN FROM THE
GULF OF MEXICO (30S TO 40S DEG F). AS MENTIONED ABOVE, LEFT POPS
ALONE FOR THIS PERIOD DUE TO THE TIMING DIFFERENCES. THE 12Z ECMWF
IS ALSO DRIER THAN THE 00Z ECMWF WHICH FURTHER COMPLICATES THE
WEATHER SCENE IN ABOUT A WEEK FROM NOW. -SUGDEN
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 16 37 18 39 / 0 10 10 0
GCK 14 32 17 36 / 0 10 10 0
EHA 15 34 18 35 / 0 10 10 0
LBL 16 39 19 39 / 0 10 10 0
HYS 14 31 15 33 / 10 10 10 0
P28 18 43 21 41 / 0 10 10 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN99/99
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1118 PM CST WED DEC 7 2011
...AVIATION UPDATE...
.DISCUSSION...
SEE PREV DISCUSSION.
&&
.AVIATION...
THE LATEST RUC AND NAM FORECAST SOUNDINGS DO NOT COOL SFC TEMPS OFF
AS MUCH AS EARLIER RUNS. BECAUSE OF THIS THEY ARE LESS AGGRESSIVE IN
SATURATING THE BOUNDARY LAYER. SINCE CONDITIONS ARE GOOD FOR
RADIATIONAL COOLING AND THE POTENTIAL FOR SOME GROUND FOG EXISTS...
WILL KEEP A MENTION FOR TOP AND MHK WHERE THE KS RIVER COULD PROVIDE
ADDITIONAL BOUNDARY LAYER MOISTURE.
MODELS CONTINUE TO SHOW A WEAK SHORTWAVE MOVING ACROSS THIS
AFTERNOON AND EVENING. FORCING FOR PRECIP IS NOT OVERWHELMING.
HOWEVER IT LOOKS LIKE THERE COULD BE A 3 TO 4 HOUR WINDOW FOR SOME
LIGHT SNOW...ESPECIALLY ACROSS NORTHEAST KS. WITH GOOD CONSENSUS IN
MODEL QPF...HAVE SOME CONFIDENCE IN LIGHT SNOW DEVELOPING WITH
INTENSITY BEING FAIRLY LIGHT AND LITTLE ACCUMULATION. THEREFORE ONLY
TAKE THE TAFS TO MVFR IN SPITE OF THE MET MOS SHOWING IFR CONDITIONS.
WOLTERS
&&
.PREV DISCUSSION... /248 PM CST WED DEC 7 2011/
WEAK MID-LEVEL DISTURBANCE COMBINED WITH MID-LEVEL ISENTROPIC LIFT
HAS LED TO AN AC DECK ACROSS EASTERN NEBRASKA...FAR NORTHEAST KS
AND AREAS EAST THIS AFTERNOON. THIS SHOULD MOVE OFF TONIGHT WITH
SOME CLEARING EXPECTED. WEAK PRESSURE GRADIENT TONIGHT COMBINING
WITH MOSTLY CLEAR SKIES COULD LEAD TO SOME LIGHT FOG IN PLACES
NEAR SUNRISE. WOULD NOT EXPECT IT TO BE DENSE OR WIDESPREAD AND
HAVE NOT MENTIONED IT IN THE GRIDS/FORECAST.
ON THURSDAY...A LITTLE MORE DEFINED UPPER TROUGH SWINGS
SOUTHEASTWARD OUT OF NEBRASKA WITH ASSOCIATED MID AND UPPER LEVEL
FORCING. ATMOSPHERE QUITE STABLE AND MOISTURE LACKING...SO WHILE
SATURATION WILL OCCUR AND SNOW WILL RESULT...DO NOT EXPECT ANY
SIGNIFICANT ACCUMULATION. AFTERNOON CHANCES SHOULD REMAIN NORTH
OF I70. GDP
THURSDAY NIGHT THROUGH SATURDAY...WEAK FRONTOGENESIS CONTINUES
THROUGH AT LEAST THE EARLY EVENING HOURS ON THURSDAY AS THE TROF
NEARS. LOW TO MID LEVELS SHOULD BE SATURATED ENOUGH FOR LIGHT SNOW
TO SWING EAST THROUGH MAINLY NORTHERN AND CENTRAL LOCATIONS. MAY
SEE THE SNOW LAST LONG ENOUGH FOR VERY LOW ACCUMULATIONS TO
RESULT...WITH THIS FAST-MOVING SYSTEM EXITING BY DAWN. NAM AND GFS
ARE QUITE SIMILAR WITH ANOTHER AREA OF LIGHT SNOW DEVELOPING IN
CENTRAL NEBRASKA LATE IN THE NIGHT...APPARENTLY TIED TO ANOTHER
AREA OF WEAK FRONTOGENESIS AROUND 850MB AS THE UPPER TROF PASSES.
WITH QUESTIONS ON THE POSITIONING OF THIS FEATURE AND THE LIKELY
LIMITED IMPACT OF THIS SHALLOW AND TRANSIENT FORCING...WILL NOT
MENTION ANY PRECIP/FLURRIES AT THIS POINT. SKIES SHOULD SLOWLY
CLEAR FRIDAY AND MAY SET THE STAGE FOR A RATHER COOL FRIDAY NIGHT
IF SNOWPACK AND WEAK WIND FIELDS CAN ALIGN A BIT BETTER THAN
EXPECTED CURRENTLY. WARM AIR ADVECTION ENSUES BY LATE IN THE NIGHT
FOR A MUCH WARMER SATURDAY ON SOUTHWEST WINDS. KP
SATURDAY NIGHT THROUGH WEDNESDAY...ON SUNDAY WEAK WARM AIR ADVECTION
WILL CONTINUE ACROSS THE CENTRAL U.S. WITH WEAK UPPER LEVEL RIDGING
IN PLACE. SOUTHERLY FLOW WILL CONTINUE ACROSS THE REGION WITH HIGH
PRESSURE OVER THE OHIO RIVER VALLEY AND LEE CYCLOGENESIS TAKING
PLACE. WITH PLENTY OF INSOLATION TEMPERATURES WILL WARM INTO THE LOW
AND MID 40S ON SUNDAY. LATE MONDAY INTO TUESDAY MORNING A TROUGH
WILL MOVE ACROSS THE NORTHERN PLAINS. THIS TROUGH WILL PUSH A WEAK
COLD FRONT THROUGH THE CWA LATE MONDAY INTO TUESDAY MORNING. COLD
AIR ADVECTION WILL BE SHORT-LIVED WITH BOTH THE GFS AND ECMWF
INDICATING AN UPPER LEVEL TROUGH THAT WILL EJECT OUT OF THE DESERT
SOUTHWEST INTO THE CENTRAL PLAINS LATE TUESDAY INTO WEDNESDAY.
MODELS INDICATE THAT MOISTURE RETURN AND LIFT AHEAD OF THIS SYSTEM
WILL BE SUFFICIENT FOR PRECIPITATION ACROSS THE CWA LATE TUESDAY
NIGHT AND CONTINUING INTO THE DAY ON WEDNESDAY. AT THIS TIME...THE
DOMINANT PRECIPITATION TYPE SHOULD BE RAIN WITH TEMPERATURES WARMING
OVERNIGHT TUESDAY WITH 850 MB TEMPERATURES APPROACHING 6-10 DEGREES
CELSIUS TUESDAY NIGHT. A WARM FRONT IS EXPECTED TO RACE NORTH OF THE
CWA DURING THE DAY ON WEDNESDAY WITH HIGHS PUSHING INTO THE UPPER
40S AND LOWER 50S ACROSS THE CWA. MEA
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1211 AM EST THU DEC 08 2011
...Updated Aviation Discussion...
...Forecast Update...
Did a minor update to account for current temperature and sky
trends. The remaining forecast is on track. Updated products have
been issued.
Dry air continues to migrate into the forecast area. Current
T/Td spreads of generally 6-9 degrees yields relative humidity
values in the 70 to low 80 percent range. Latest guidance,
particularly LAMP data, handle the current conditions well and keep
a 4-5 degree spread through the morning hours. With this T/Td spread
and westerly wind speeds in the 3-5 mph range overnight, believe it
will be difficult for fog formation. Additionally, the gusty
northwest winds this afternoon across much of the forecast area
actually aided in drying the surface a bit. At this time, the only
potential location for fog formation would be confined to the water
surfaces of rivers and lakes in the form of steam fog (also known as
evaporation fog), as this cold airmass works over slightly warmer
river/lake waters. Once again, this would be localized to very near
the water surface, if fog were to form.
&&
.Short Term (Tonight and Thursday)...
First off, snow band was not as impressive as the HRRR earlier today
made it out to be. County officials in our Lake Cumberland region
have all indicated very little snow stuck. Webcams from that area
also look mostly just wet and not white. Had some pictures with snow
from the LEX-area webcams in a brief band that went through their in
the last couple of hours, but likewise nothing has accumulated.
Surface temperatures are just too warm, in the mid 30s along with
the still wet grounds from the rain earlier in the week.
Sunshine is poking out some in cloud cover west of a KLEX to
Scottsville line. With any heating though, additional low clouds are
developing. These clouds may yet produce some scattered very light
flurries across central KY, but temperatures will not be cool enough
where these clouds are to promote lots of snow. With the cloud
cover, temperatures are holding to around 40 degrees at most.
Skies should clear out overnight as deep dry air moves into the
region. High pressure will move in south of the region, so expect a
general westerly wind through the night. Expect temperatures to fall
into the 20s areawide overnight under these clear skies. Sheltered
locations may see the low 20s.
High pressure will be centered over the Appalachians during the day
Thursday. Thus expect a southwesterly flow. Clear skies should allow
us to reach the low/mid 40s areawide, roughly 5 degrees below normal.
.Long term (Thursday night - Wednesday)...
A digging shortwave will dive from the northern plains into the
lower Great Lakes on Friday. Moisture return ahead of this system
will be limited and therefore continued to only mention flurries in
the forecast early Friday morning across southern Indiana, gradually
working eastward across north central Kentucky and the Bluegrass
through the day. Temperatures ahead of the front will likely warm
enough for just sprinkles in the late morning and afternoon. In the
morning and the evening, moisture to about 700 mb should yield
some potential for ice crystals as temps at this level will be
around -10 C. No impacts from these flurries are anticipated.
Otherwise, cold frontal boundary moves through Friday afternoon and
evening with a cold airmass lurking for the weekend. Lows Friday
night are expected to drop into the lower 20 in most spots, with a
few upper teens possible across southern Indiana and perhaps the
Bluegrass. High temperatures on Saturday will struggle, only making
it to the low and mid 30s. Saturday night will bring more
temperatures right around the 20 degree mark.
Sunday into the middle of next week, mid level flow will gradually
transition from a progressive zonal flow then try to head back toward
the classic La Nina pattern we have been seeing which would yield
southwest flow aloft with a ridge to our southeast and a developing
trough over the western CONUS. Will keep forecast through Wednesday
dry, although some signs point to another potent system tracking
into the region possibly Thursday or Friday. Although this is pretty
far out, confidence in the recent pattern supported by
teleconnections could lead to another substantial precipitation
event across the Ohio Valley. Stay tuned.
Highs through the first half of next week will gradually moderate
toward the mid 40s, with upper 40s and low 50s ahead of the next
system possible on Wednesday. Lows each night will be in the 20s,
warming to the low 30s by Wednesday morning.
&&
.Aviation (06Z TAF Issuance)...
Latest satellite imagery reveals clear skies at the terminals this
evening. VFR conditions are expected through the TAF period as high
pressure builds in from the west. Dry air continues to push into
the region and T/Td spreads are still forecast to be large enough to
limit fog formation overnight. In fact, a look at all of the
available 08/00Z guidance shows very little if any fog development
overnight as the surface winds stay up around 2-4 knots. Winds
should slacken late tonight and then resume after sunrise out of the
southwest as high pressure moves into the Appalachian mountains.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........MJP
Short Term.......RJS
Long Term........BJS
Aviation.........MJ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1234 AM EST THU DEC 8 2011
UPDATED AVIATION DISCUSSION FOR 06Z TAFS
.SYNOPSIS /ISSUED AT 354 PM/...
WV IMAGERY AND RUC ANALYSIS INDICATED CYCLONIC MID/UPPER LEVEL FLOW
AROUND A VORTEX OVER HUDSON BAY BRINGING NRN STREAM WNW FLOW FROM
SRN CANADA INTO THE UPPER GREAT LAKES. AN UPSTREAM SHORTWAVE TROUGH
WAS MOVING THROUGH SRN MANITOBA WITH ANOTHER TRAILING SHRTWV OVER
NRN SASK. AT THE SFC...WINDS WERE VEERING W TO WNW BEHIND A
TROUGH/FRONT THAT MOVED THROUGH THIS MORNING. A TRAILING ARCTIC
FRONT NEAR LAKE WINNIPEG WAS DROPPING TOWARD THE AREA WITH MUCH
COLDER AIR BEHIND IT WITH TEMPERATURES FROM -5 TO 5F OVER NORTHERN
MANITOBA/SASK. VIS LOOP INDICATED CLEARING SKIES OVER THE WEST HALF
OF THE CWA AS DRIER AIR MOVES INTO THE REGION. EVEN WITH 850 MB
TEMPS AROUND -11C...SKIES HAD CLEARED OVER MUCH OF WRN LAKE SUPERIOR.
&&
.SHORT TERM...TONIGHT AND THURSDAY
CLOUDS AND SCT LIGHT LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO
REDEVELOP OVER WRN LAKE SUPERIOR INTO WRN UPPER MI THIS EVENING AS
GREATER LOW LEVEL MOISTURE MOVES TOWARD THE AREA...PER VIS LOOP.
PASSAGE OF THE SASK SHRTWV AND ARCTIC FRONT THU MORNING WITH
INCREASING 850-700 MB MOISTURE AND INVERSION HEIGHTS CLIMBING AROUND
8K FT WILL PROVIDE A SIGNIFICANT BOOST TO THE LAKE EFFECT SNOW. SNOW
GROWTH ALSO LOOKS FAVORABLE AS THE DGZ WILL BE RIGHT IN THE BEST
OMEGA/UPWARD MOTION. GIVEN MODEL QPF AND SNOW/WATER RATIOS
APPROACHING 30/1 WOULD NOT BE SURPRISED TO SEE PERIODS OF MODERATE
TO HEAVY SNOWFALL. THE MOST PERSISTENT LOW LEVEL CONV AND CHANCE FOR
GREATEST ACCUMULATION IS EXPECTED FROM FAR NE ONTONAGON COUNTY INTO
CENTRAL HOUGHTON COUNTY...FROM GREENLAND TO TWIN LAKES. INCREASINGLY
CONVERGENT WRLY FLOW. INCREASING WINDS GUSTING TO NEAR 30 MPH AT
TIMES ON THURSDAY WILL ALSO SHARPLY REDUCE VSBYS IN BLOWING SNOW AS
WELL AND CAUSE DRIFTING SNOW ACROSS THE ROADS. SO...WITH THE
LIKELIHOOD OF AN EXTENDED PERIOD OF LES...HEAVY SNOW AT TIMES...A
LAKE EFFECT SNOW WARNING WAS ISSUED. CONFIDENCE IN ACCUMULATIONS BY
LATE THURSDAY IS LIMITED BY UNCERTAINTY ON WHERE THE HEAVIER BANDS
WILL DEVELOP AND HOW LONG THEY WILL PERSIST. SNOWFALL GENERALLY FROM
3 TO 7 INCHES IS LIKELY WITH SOME HIGHER LCL AMOUNTS.
LOCATIONS NEAR LAKE SUPERIOR EAST OF MUNISING...FROM GRAND MARAIS TO
TWO HEART MAY ALSO SEE A PERIOD OF HEAVIER LES IF THE EXPECTED
DOMINANT BAND SAGS SOUTHWARD WITH SLIGHTLY VEERING WINDS THU.
UNCERTAINTY REMAINS WHETHER THE HEAVIER SNOW WILL REMAIN OFFSHORE OR
MOVE INLAND...SO NO HEADLINES WERE ISSUED AT THIS TIME.
.LONG TERM /THURSDAY NIGHT THROUGH NEXT WEDNESDAY/...
SIGNIFICANT LAKE EFFECT SNOW IS THE MAIN CONCERN FOR THE INITIAL
PORTION OF THE LONG TERM.
LARGE SCALE TROUGH WITH COLDEST AIR OF SEASON THUS FAR TO PUSH INTO
THE AREA SETTLES OVER MUCH OF THE EASTERN CONUS TO END THE WEEK.
NOT MUCH IN THE WAY OF LARGER SCALE SHORTWAVES THAT WILL BRING
WIDESPREAD SNOW TO THE AREA...BUT SIGNIFICANT LK EFFECT FOR WEST
FLOW AREAS IS LIKELY AS H85 TEMPS TUMBLE TO AROUND -18C BY FRIDAY.
MODEL SOUNDINGS INDICATE LAKE INDUCED CAPES AOA 600J/KG WHILE LAKE
EQUIBRIUM LEVELS ARE OVR 10 KFT AGL. HIGHER OVERWATER INSTABILITY
IS SUPPLEMENTED BY STRONG LOW-LEVEL (SFC-H95) CONVERGENCE.
MODELS ARE ACTUALLY IN VERY GOOD AGREEMENT WITH OVERALL SCENARIO
THOUGH SUBTLE SHIFTS IN BLYR WINDS MAKE ALL THE DIFFERENCE AS TO
THE LOCATIONS THAT END UP WITH THE HIGHEST SNOW AMOUNTS. BY LATE
THURSDAY AND INTO THURSDAY NIGHT...SHEAR WITHIN THE SFC-H8 LAYER
IS QUITE LOW...LEADING TO BETTER CHANCE THAT DOMINANT BANDS CAN
ORGANIZE. WINDS BECOMING WESTERLY AT 925MB WITH WSW OR SW SFC WINDS
OVR UPR MI (ENHANCED BY NIGHTTIME LAND BREEZES) WOULD FAVOR STRONGEST
CONVERGENCE/HEAVIER SNOW BANDS OVR WESTERN UPR MI FM ONTONAGON
THROUGH TWIN LAKES/PAINESDALE. WARNING WILL CONTINUE FOR THOSE AREAS
THROUGH LATE FRIDAY FOR THIS PROLONGED HEAVY LAKE EFFECT SNOW EVENT.
STORM TOTALS OVER A FOOT SEEM PRETTY LIKELY IF THE PRIMARY SNOW BAND
STAYS STATIONARY FOR REASONABLE AMOUNT OF TIME.
HIGHER TERRAIN AREAS OF REST OF HOUGHTON COUNTY WILL ALSO SEE
OFF-AND-ON HEAVIER SNOW SHOWERS. ALSO EXPECT SOME HEAVIER SNOW TO
OCCUR OVR SOUTHERN PORTIONS OF HOUGHTON COUNTY...MAINLY NORTH OF
M-38. ADVY WILL COVER THIS POSSIBILITY. EXPECT VERY LITTLE IF ANY
SNOW TOWARD KENTON/SIDNAW ALONG M-28. KEWEENAW COUNTY IS MORE OF A
QUESTION MARK AS THE MORE WNW BLYR WINDS THERE ARE NOT AS FAVORABLE.
STILL THOUGH...DEGREE OF INSTABILITY AND SUFFICIENT MOISTURE PRESENT
COULD LEAD TO LOCALIZED HEAVY AMOUNTS OVR HIGHER TERRAIN THERE AS
WELL. AN ADVISORY WILL HANDLE THIS FOR NOW...THOUGH LATER UPGRADE
COULD BE NEEDED. EXPECT QUIET WEATHER FOR REST OF THE CWA THURSDAY
NIGHT INTO FRIDAY. TEMPS WILL BE ON THE CHILLY SIDE THOUGH WITH
NIGHTTIME LOWS THURSDAY NIGHT TOWARD THE ZERO MARK OVR INTERIOR SW
UPR MI AND HIGHS ON FRIDAY MAINLY STAYING IN THE TEENS.
BY LATE FRIDAY...WEAKER TROUGH FCST TO SLIDE THROUGH THE AREA MAY
VEER WINDS TO MORE NW LEADING TO INCREASED CHANCES OF LAKE EFFECT
SNOW SHOWERS INTO FAR EASTERN SECTION OF CWA...MAINLY EAST OF
MUNISING AND WELL NORTH OF NEWBERRY. LAKE EFFECT SNOW PARAMETER
DEVELOPED BY NWS GAYLORD WHICH INCORPORATES 1000-850MB
SHEAR/850-700MB RH/H85 TEMPS INDICATES FAVORABLE SETUP FOR HEAVY
SNOW RATES IN THOSE EASTERN AREAS FRIDAY AFTN/FRIDAY EVENING.
SNOWFALL RATES UP TO 2 INCHES PER HOUR COULD OCCUR IN THOSE AREAS
AND HEADLINES MAY BE NEEDED AT SOME POINT. HOWEVER...WILL LEAVE
THOSE DECISIONS TO LATER SHIFTS AS EXPECT VERY LITTLE SNOWFALL IN
THOSE AREAS THROUGH FRIDAY MORNING.
TROUGH AND COLDER AIR SFC-H85 SLOWLY HEAD INTO LOWER GREAT LAKES
FRIDAY NIGHT INTO SATURDAY. WARM AIR ADVECTION STARTS UP BY SATURDAY
LEADING TO A PUSH OF ISENTROPIC ASCENT 285-290K (750-650MB) ACROSS
MUCH OF THE CWA. UVM IN THE LAYER FAIRLY STRONG...BUT TROUBLE IS
THERE IS DRY AIR LINGERING BLO H85 THRU THE DAY. COULD BE SOME
FLURRIES OR LIGHT SNOW SHOWERS...BUT BETTER SATURATION WILL KEEP THE
GREATER CHANCE OF ACCUMULATING SNOWS MORE INTO ONTARIO. GUSTY SW
WINDS WILL ADD CHILL TO THE AIR DESPITE SFC TEMPS REBOUNDING INTO
LOWER TO MIDDLE 20S.
FOR THE EXTENDED...TROUGH THAT WAS OVER THE AREA FOR MUCH OF THIS
WEEK IS FCST TO EASE INTO EASTERN CANADA LEADING TO MORE OF A ZONAL
FLOW PATTERN/WARMING TREND BY EARLY NEXT WEEK. WEAK SHORTWAVE/WARM
FRONT SLIDES ACROSS UPR LAKES MONDAY BUT MOISTURE IS MINIMAL SO DO
NOT EXPECT A WHOLE LOT OF PRECIPITIATON. BETTER CHANCE OF
PRECIPITATION WOULD BE FARTHER NORTH CLOSER TO H85-H7 FRONTOGENESIS
AND RIGHT ENTRANCE REGION OF UPR JET OVR ONTARIO. ANOTHER TROUGH
FORMING OVR SCNTRL CANADA IS FCST TO MOVE ACROSS THE UPR GREAT LAKES
LATE TUESDAY INTO WEDNESDAY. DIFFERENCES BEGIN TO APPEAR WITH REGARD
TO DEPTH OF TROUGH BY WEDNESDAY. LAST TWO RUNS OF GFS CLOSED THE
TROUGH OFF OVR UPR MISSISSIPPI RIVER VALLEY/UPR LAKES. MEANWHILE...
RECENT RUNS OF THE ECMWF AND PREVIOUS RUNS OF GFS INDICATED MORE OF
A PROGRESSIVE SYSTEM...WITH DEEPER SYSTEM FORMING OVR CNTRL PLAINS
MID-LATE NEXT WEEK. ENSEMBLES FM GFS/ECMWF/CANADIAN SHED LITTLE
LIGHT ON THE SUBJECT WITH MIXED SIGNALS IN TERMS OF STRENGTH AND
MOVEMENT OF THE TROUGHS. DOES SEEM THAT AT LEAST ECMWF WOULD SUPPORT
BETTER CHANCE OF ORGANIZED PRECIPITATION IN THE MIDWEEK TIME FRAME.
WILL NOT PUT TOO MUCH EMPHASIS ON THIS YET THOUGH AS SUPPORT FOR
THAT IDEA REMAINS LIMITED SUPPORT LOOKING AT OTHER AVILABLE GUIDANCE
AND ENSEMBLES.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
PASSAGE OF THE FIRST IN A SERIES OF LO PRES TROFS WL BRING IFR
CONDITIONS TO THE EXPOSED CMX LOCATION THAT WL EXPERIENCE MORE SGNFT
LK MOISTENING DESTABILIZATION EARLY THIS MRNG. ALTHOUGH THERE MAY BE
SOME -SHSN AT IWD AND SAW...ANY REDUCED CIG/VSBY WL BE MORE LIMITED
WITH LESS LK MODIFICATION AND/OR DOWNSLOPE WIND COMPONENT. EXPECT A
PERIOD OF IMPROVEMENT TOWARD SUNRISE AS A TRAILING SFC HI PRES
RDG/AXIS OF DRIER AIR FOLLOWING THE TROF SHIFTS OVHD. BUT THE LULL
WL BE ONLY TEMPORARY WITH A SECOND LO PRES TROF FOLLOWING THRU AT
MID MRNG. THIS DEEPER TROF WL BE FOLLOWED BY STRONGER W WINDS THAT
WL CAUSE GUSTS AS HI AS 30 KT OVER THE EXPOSED KEWEENAW/CMX. THE
COMBINATION OF FALLING LK EFFECT SN AND BLSN WHIPPED UP BY THESE
STRONG WINDS WL LIKELY LEAD TO LIFR CONDITIONS AT THAT SITE. THE DRY
NATURE OF THE ARCTIC AIRMASSES WL LIMIT DETERIORATION AT IWD AND
ESPECIALLY SAW...WHERE THE PREVAILING WLY WIND COMPONENT WL
DOWNSLOPE/DRY AND RESULT IN PREDOMINANT VFR CONDITIONS.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
WINDS MAINLY OUT OF A WESTERLY DIRECTION OVER 20KTS WILL PREVAIL
THROUGH MUCH OF THE PERIOD. THE WINDS/WAVES ALONG WITH PLENTY OF
COLD AIR WILL RESULT IN THE POTENTIAL FOR FREEZING SPRAY TONIGHT
INTO FRIDAY. WESTERLY GALES ARE EXPECTED TO RETURN AROUND SUNRISE
THURSDAY BEHIND AN ARCTIC FRONT OVER THE WEST HALF...BEFORE
EXTENDING THROUGH CENTRAL AND EASTERN LS THROUGH EARLY THURSDAY
EVENING.
EXPECT STRONG HIGH PRESSURE ACROSS SW CANADA TO WEAKEN ACROSS THE
PLAINS STATES FRIDAY...WHILE EXTENDING A RIDGE ACROSS LS BY FRIDAY
NIGHT. LOW PRESSURE OVER MANITOBA SATURDAY MORNING WILL SLIDE ACROSS
ONTARIO SATURDAY AFTERNOON AND EVENING...WHILE DRAGGING A TROUGH
OVER LS. A PERIOD OF SW GALES IS POSSIBLE SATURDAY AHEAD OF THE LOW.
ANOTHER LOW PRESSURE SYSTEM...OVER THE DAKOTAS SUNDAY MORNING...WILL
LIKELY FILTER ACROSS LAKE SUPERIOR SUNDAY NIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST FRIDAY FOR MIZ002-003.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ001-084.
LAKE SUPERIOR...
GALE WARNING FROM 7 AM THIS MORNING TO 1 AM EST FRIDAY FOR
LSZ263>267.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
355 AM EST THU DEC 8 2011
.SYNOPSIS...
HIGH PRESSURE THURSDAY. COLD FRONT FRIDAY NIGHT. HIGH PRESSURE
FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
CLEARING ACROSS THE LOWLANDS HAS RESULTED IN STRONG RADIATIONAL
COOLING. STILL EXPECTING TEMPS TO CRASH THROUGH EARLY MORNING HOURS.
CLEARING HAS STALLED A BIT IN THE MOUNTAINS WHERE EKN AND BKW STILL
REPORTING BKN CLOUD COVER. EXPECTING THESE SITES TO CLEAR OUT
COMPLETELY BY 10Z.
CURRENT IR SATELLITE IMAGERY SHOWS SHALLOW CLOUD DECK KNOCKING ON
THE DOORSTEPS OF OUR SE OHIO COUNTIES. LATEST RUN OF THE RUC HAS
THIS FEATURE DIAGNOSED WELL WITH COINCIDING 850MB MOISTURE MOVING
ACROSS OUR NORTHERN TIER COUNTIES AND SLOSHING UP AGAINST THE HIGH
TERRAIN OF THE NE MNT COUNTIES. RESULTANT RUC SOUNDINGS DISPLAYED IN
BUFKIT TRYING TO DEVELOP LOW STRATUS AGAINST THE MOUNTAINS AROUND
12Z. NOT COMPLETELY SOLD ON THIS AS RUC 850MB MOISTURE SHOULD ERODE
FURTHER DOWNSTREAM OF THE SOUTHERN GREAT LAKES. ALSO...WARMING TREND
IN 850MB TEMPS SHOULD HELP TO DRY THE COLUMN FURTHER. ALL
TOLD...WILL NOT INCLUDE STRATUS DEVELOPMENT IN THIS PACKAGE...BUT
WILL CONTINUE TO MONITOR FORTHCOMING GUIDANCE AND TRENDS.
A CHANGE OF PACE TODAY...RELATIVE TO THE LAST FEW DAYS. SUNNY SKIES
WITH COLDER TEMPERATURES ARE EXPECTED AS CWA IS NOW UNDER THE
CONTROL OF A SURFACE HIGH.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
NEXT SYSTEM TO DEAL WITH WILL BE A MOISTURE STARVED COLD FRONT
EXPECTED TO ENTER THE SOUTHEAST OHIO ZONES AFTER 18Z FRIDAY. SREF
PROBABILITIES OF ACCUMULATING PRECIPITATION ARE ON THE LOW
SIDE...BELOW 50 PERCENT...AND WILL HAVE A TOUGH TIME SATURATING
ABOVE ABOUT 750MB. THAT BEING SAID...SNOW SHOWERS ARE POSSIBLE UPON
PASSAGE...LIKELY NOT ACCUMULATING OR GIVING TRACE ACCUMULATIONS.
OF MORE SIGNIFICANCE IS THE AIRMASS BEHIND THE COLD FRONT. 500MB
HEIGHTS DROP IN THE POST FRONTAL TROUGH...AND 850MB TEMPERATURES
ALSO DECREASE INTO THE MINUS TEENS COME SATURDAY. THERMAL TROUGH AT
THIS LEVEL WILL PERSIST OVER THE NORTHEAST MOUNTAINS...AND WITH A
CLEARING SKY...SATURDAY NIGHT TEMPERATURES LOOK VERY COLD. STRONG
HIGH PRESSURE SETTLES IN OVER THE REMAINDER OF THE WEEKEND IN A
LARGELY DRY PATTERN THROUGH EARLY NEXT WEEK.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
A BREAK FROM ANY RAIN OR SNOW WILL OCCUR DURING THE FIRST SEVERAL
DAYS OF THIS PERIOD. A POCKET OF COLD AIR WILL BE IN PLACE THANKS TO
SURFACE HIGH PRESSURE. AS THE SURFACE HIGH PRESSURE SLIDES
NORTHEAST...POCKET OF COLDEST TEMPERATURES WILL ALSO FOLLOW. SUNDAY
THROUGH TUESDAY WILL FEATURE MOSTLY SUNNY SKIES DURING THE DAY AND
CLEAR AND COLD AT NIGHT. THE NEXT SYSTEM WILL APPROACH THE AREA
DURING THE MID WEEK. WILL CONTINUE TO MONITOR THE SYSTEM AS IT
DEVELOPS.
GENERALLY FOLLOWED HPC GUIDANCE WITH ONLY A FEW MODIFICATION.
&&
.AVIATION /09Z THURSDAY THROUGH MONDAY/...
CONDITIONS CONTINUE TO IMPROVE EARLY THIS MORNING FROM W TO E.
MVFR IN MOUNTAINS AS CLOUD COVER AND -SN LINGER A FEW HOURS
LONGER.
CLEAR SKY WEST FROM CRW-CKB LINE RESULTING IN VFR...EXPECTING
THIS TREND TO CONTINUE PUSHING EAST BETWEEN 06Z TO 12Z.
CEILING UNLIMITED AND VSBY UNRESTRICTED 12Z TO 18Z.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: THERE IS A CHANCE THAT SOME STRATUS MAY REFORM
IN WEST VIRGINIA AT 1 TO 2 THSD FT ON EITHER SIDE OF DAWN/12Z
THURSDAY. BUT WITH WIND AND LOWERING DEW POINTS...DID NOT GO WITH
THAT SCENARIO IN THE 00Z TAF FORECASTS.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE THU 12/08/11
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EST 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY M M M M H H H H H H H H
EKN CONSISTENCY M M H M M H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H M M H H H H
AFTER 06Z FRIDAY...
NO WIDESPREAD IFR EXPECTED.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...26/TAX
NEAR TERM...TAX
SHORT TERM...26
LONG TERM...JB
AVIATION...TAX
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1058 PM CST WED DEC 7 2011
.DISCUSSION.../ISSUED AT 758 PM CST/
WENT AHEAD AND INCREASE LOWS ABOUT 5 TO 8 DEGREES IN MOST SPOTS AS
CLOUD COVER NOW SEEMS TO BE LOCKED IN FOR THE NIGHT...ESPECIALLY
WITH THE APPROACH OF THE UPPER LEVEL WAVE IN THE NORTHERN ROCKIES.
SO...BASICALLY LOOKING AT TEMPERATURES RANGING FROM AROUND THE MID
TEENS TO LOWER 20S. DID ADD SOME FLURRIES AND A SLIGHT CHANCE FOR
LIGHT SNOW IN THE FAR SOUTHERN CWA FRO 9-12Z AS THE RUC AND HRRR
CONTINUE TO INDICATE THAT SOME SNOWFALL MAY GET SQUEEZED OUT OF THE
MID LEVEL DECK MOVING SOUTHWARD. THIS DOES NOT SEEM COMPLETELY OUT
OF THE QUESTION SINCE THE THERMAL PROFILE BECOMES MORE DENDRITIC IN
THE STRONGER FORCING AT THIS TIME AND OUR LOWEST LEVELS ARE NOT
COMPLETELY DRY SO COULD SEE SOME FLAKES WITH THE BETTER CHANCES NEAR
THE MISSOURI RIVER FROM ABOUT 9Z THROUGH 15Z. /08
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
GENERAL VFR CONDITIONS EXPECTED THROUGH 06Z FRI. VERY SMALL THREAT
FOR MARGINAL MVFR STRATUS LATE TONIGHT AND EARLY MORNING BEHIND
COLD FRONT...BUT BELOW MENTIONABLE THRESHOLD...AT WHICH TIME A FEW
FLURRIES AT BEST FOR KSUX AREA...WHICH SHOULD NOT BREACH INTO MVFR
VISIBILITIES. /CHAPMAN
&&
.PREV DISCUSSION.../ISSUED AT 252 PM CST/
FRONTAL BOUNDARY CONTINUES TO DROP SOUTHWARD ACROSS THE REGION THIS
AFTERNOON...AND WILL EXIT THE AREA BY THIS EVENING. MAIN CHALLENGE
TONIGHT WILL BE IN TEMPERATURES...WITH STRONG COLD AIR ADVECTION
BEHIND THE FRONT...MUTED BY CLOUD COVER EXPECTED TO BE OVER MUCH OF
THE AREA DURING THE OVERNIGHT HOURS. WITH BREAKS IN THE
CLOUDS...WILL SEE TEMPERATURES FLUCTUATE DEPENDING ON THE CLOUD
COVER...THOUGH WILL SEE A GENERAL DOWNWARD TREND THROUGH THE NIGHT
WITH LOWS JUST UNDER 10 THROUGH THE HURON TO BROOKINGS CORRIDOR...TO
THE MID TEENS ALONG THE MISSOURI RIVER CORRIDOR WHERE CLOUDS WILL BE
MORE DOMINANT.
MODELS CONTINUING SLIGHT SOUTHWARD TREND WITH PRECIP CHANCES ON
THURSDAY...AS NORTHERN STREAM WAVE DROPS SOUTHEAST INTO THE NORTHERN
PLAINS. 700MB FRONTOGENESIS STILL HUGS THE MISSOURI RIVER VALLEY...
HOWEVER MOST MODELS SHOWING A DRY LAYER IN THE ATMOSPHERE NORTH OF
THE RIVER THAT WILL LIMIT NORTHWARD EXTENT OF ACCUMULATING PRECIP.
HAVE SCALED POPS BACK TO JUST OUR FAR SOUTHERN AREAS...GENERALLY
SOUTH OF LAKE ANDES/KYKN/KSLB LINE...WITH JUST A FEW TENTHS OF SNOW
AT BEST IN THESE AREAS. 850MB BAROCLINIC ZONE LINGERS FROM NORTH
CENTRAL NEBRASKA INTO SOUTHWEST SOUTH DAKOTA INTO THE EVENING AS THE
MAIN WAVE DROPS THROUGH THE DAKOTAS....AND THIS COULD KEEP SOME
LIGHT SNOW OR FLURRIES GOING JUST TO OUR SOUTHWEST INTO THURSDAY
EVENING. WILL KEEP IT DRY IN OUR AREA...THOUGH SOME MID CLOUDS WILL
LIKELY HANG AROUND IN THE WESTERN PORTIONS OF THE MISSOURI RIVER
VALLEY THROUGH 06Z BEFORE DRIER MID LEVEL AIR PUSHES SOUTH WITH THE
WAVE.
FOCUS FOR THE REMAINDER OF THE WEEK AND INTO THE WEEKEND WILL BE ON
TEMPERATURES...WITH POTENTIAL FOR SOME DECENT RADIATIONAL NIGHTTIME
COOLING. SURFACE RIDGE AXIS SHIFTS INTO NEBRASKA SO WILL LIKELY NOT
SEE WINDS GO COMPLETELY CALM EXCEPT IN MORE SHELTERED AREAS. HOWEVER
EVEN WITH RELATIVELY LIGHT WEST-SOUTHWEST WINDS EXPECTED OVER THE
SNOWPACK AREAS...SHOULD SEE QUICK EVENING DROPS IN TEMPERATURES
ACROSS OUR SOUTHEAST THURSDAY AND FRIDAY NIGHTS...WITH NON-DIURNAL
RISE IN TEMPERATURES EXPECTED LATER FRIDAY NIGHT AS WINDS/CLOUDS
INCREASE AHEAD OF WARM FRONT. DAYTIME TEMPERATURES SHOULD SEE
GRADUAL DECREASE IN EFFECT OF SNOWPACK ON READINGS...THOUGH COULD
STILL HOLD HIGHS BACK A FEW DEGREES ON FRIDAY WITH FULL SUNSHINE AND
LIMITED MIXING.
LONGER RANGE STILL LOOKS RELATIVELY DRY THROUGH TUESDAY...WITH
MODELS SHOWING DECENT AGREEMENT DIGGING YET ANOTHER WAVE INTO THE
SOUTHWEST CONUS WHILE SEPARATE NORTHERN STREAM TROUGH SLIDES EAST
ACROSS THE CANADIAN BORDER. WEAK WAVE SEEN EJECTING OUT OF SOUTHWEST
SYSTEM INTO THE MIDDLE MISSOURI VALLEY ON MONDAY. FORECAST SOUNDINGS
QUITE SPARSE ON MOISTURE ABOVE 850MB...BUT SIMILAR IN SHOWING STRONG
NORTHWARD PUSH OF LOW LEVEL MOISTURE/STRATUS AHEAD OF COLD FRONT IN
THE LATE NIGHT/MORNING HOURS. MOISTURE PROFILES FROM ALL MODELS ARE
REMINISCENT OF DRIZZLE SOUNDINGS...WITH LACK OF MOISTURE IN CRITICAL
ICE-BEARING LAYER ALOFT...BUT TOUGH TO PINPOINT THREAT OF POTENTIAL
FREEZING PRECIP AT DAY 4-5 RANGE SO WILL JUST GO WITH MENTION OF
LIGHT RAIN/SNOW WITH SLIGHT CHANCE POPS IN OUR FAR SOUTHEAST DURING
THE DAY MONDAY.
GREATER DIFFERENCES IN THE MODELS ARISE BY THE MIDDLE OF NEXT WEEK
IN HANDLING OF NORTHERN STREAM TROUGH AS IT MOVES ACROSS THE GREAT
LAKES AND EASTERN CANADA...AS WELL AS SOUTHWEST CONUS CUTOFF. GFS
STRONGER/SLOWER WITH NORTHERN STREAM TROUGH WHILE ALSO MAINTAINING
STRONGER SOUTHWEST SYSTEM...WITH ANOTHER RELATIVELY WEAK WAVE
LIFTING NORTHEAST THROUGH THE PLAINS MIDWEEK. ECMWF ON THE OTHER
HAND IS SLIGHTLY WEAKER/FASTER WITH THE NORTHERN STREAM TROUGH...
ALLOWING STRONGER CHUNK OF ENERGY TO LIFT NORTHEAST INTO THE PLAINS
ON WEDNESDAY. EITHER SCENARIO GIVES AT LEAST SOUTHERN PARTS OF OUR
AREA A CHANCE OF PRECIP LATE IN THE FORECAST PERIOD. MAIN DIFFERENCE
IS STRONGER ECMWF SPREADS THE PRECIP MUCH FARTHER NORTHEAST THAN THE
GFS. IN EITHER CASE...SEEMS SOME CHANCE POPS ARE WARRANTED FOR THE
DAY 7 TIMEFRAME AT THIS TIME. AFOREMENTIONED DIFFERENCES ALSO RESULT
IN DRASTICALLY DIFFERENT LOW LEVEL TEMPERATURE PROFILES...WITH ECMWF
PULLING WARMER AIR MUCH FARTHER NORTH THAN GFS WHERE NORTHERN STREAM
REMAINS DOMINANT. WITH RIDE WITH BLEND OF THE TWO SOLUTIONS AND KEEP
PRECIP TYPE AS ALL SNOW FOR NOW...BUT WARMER ECMWF COULD BRING A
THREAT OF LIQUID PRECIP INTO THE MIX AND WILL KEEP A CLOSE EYE ON
TRENDS FOR THIS OVER THE NEXT FEW DAYS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DENVER CO
826 AM MST THU DEC 8 2011
.UPDATE...CURRENT WEATHER CAMS SHOW SNOW HAS BECOME MORE
WIDESPREAD IN THE MOUNTAINS EARLY THIS MORNING. ALREADY ONE HALF
TO ONE INCH OF SNOW AS FAR SOUTH AS COPPER MOUNTAIN. RADAR AND
SATELLITE TRENDS ALONG WITH SHORT RANGE MODEL GUIDANCE OF RUC AND
HRRR SHOWING THIS SNOW WILL CONTINUE THROUGH THE REST OF THE
MORNING AND THEN DECREASE. THE SAME CAN BE SAID OVER THE NORTHEAST
CORNER OF THE STATE WHERE BAND OF SNOW WILL DROP SLOWLY
SOUTH/SOUTHEAST ACROSS THAT AREA. THE CHANCE OF SNOW WILL DECREASE
RATHER RAPIDLY TO THE SOUTH AND WEST TOWARD DENVER WHERE LOW LEVEL
AIR IS SIGNIFICANTLY DRIER AND LARGE SCALE SUBSIDENCE WILL TAKE
HOLD EARLIER IN THE AFTERNOON.
&&
.AVIATION...GOING FORECAST ON TRACK WITH ONLY A CHANCE OF LOWER
MVFR CEILINGS DEVELOPING WITH THE WEAK FRONTAL PUSH. THIS WEAK
FRONT IS STILL EXPECTED TO REACH THE FRONT RANGE AIRPORTS AROUND
18Z WITH ONLY A SLIGHT WIND SHIFT FROM AN EASTERLY DIRECTION.
&&
.PREV DISCUSSION... /ISSUED 310 AM MST THU DEC 8 2011/
LONG TERM...THERE WILL BE A DECREASING NORTHWEST FLOW ALOFT ON
FRIDAY WITH A DRYING AND SLOW WARMING TREND ACROSS COLORADO. THIS
TREND WILL CONTINUE THROUGH THE WEEKEND AS THE GREAT BASIN RIDGE OF
HIGH PRESSURE SHIFTS OVER COLORADO AND WEAKENS A BIT. TEMPERATURES
WILL WARM TO AROUND SEASONABLE NORMALS WITH PLENTY OF SUNSHINE AND
DRY CONDITIONS.
BY EARLY NEXT WEEK...SPLIT FLOW PATTERN DEVELOPS OVER MUCH OF THE
WEST WITH CLOSED LOW DEVELOPING ACROSS SOUTHERN CALIFORNIA ON MONDAY
WHILE WEAKER NORTHERN BRANCH STRETCHES A WEAK TROF ACROSS THE
NORTHERN PLAINS STATES AND BRUSHES NORTHERN COLORADO WITH A WEAK
FRONT AND COOLER TEMPERATURES. THIS PATTERN EVOLUTION SHOWS QUITE A
BIT OF UNCERTAINTY AS THE EUROPEAN/GEM SOLUTIONS ARE DEEPER WITH THE
LOW YET EJECTS IT FURTHER NORTH INTO COLORADO ON WEDNESDAY WHILE THE
GFS SOLUTION HAS THE LOW ACROSS NEW MEXICO AND TEXAS. THE EUROPEAN
TRAJECTORY WOULD FAVOR A CHANCE OF SNOW AND COOLER TEMPS WHERE VERY
LITTLE EFFECT WOULD BE FELT FROM THE FURTHER SOUTH GFS SOLUTIONS.
GFS ENSEMBLE MEMBERS NOT MUCH HELP AS SOLUTIONS ARE ALL OVER THE
BOARD. THIS ALL MEANS VERY LITTLE CHANGES TO THE OUT DAYS IN THE
LONG TERM FORECAST. WILL KEEP A SLIGHT CHANCE OF SNOW OVER THE
ENTIRE CWA FOR LATE TUESDAY AND WEDNESDAY.
$$
AVIATION...A CDFNT WILL MOVE ACROSS NERN CO LATER THIS MORNING AND
AFTN HOWEVER BOTH THE NAM AND HRRR KEEP THE MAIN PUSH OVER THE
PLAINS AND KIND OF BACK DOOR THE FNT INTO THE FNT RANGE BY EARLY TO
MID AFTN WITH VERY WK UPSLOPE. OVERALL IT LOOKS LIKE POTENTIAL FOR
LOW CEILINGS AND SOME FOG WILL REMAIN LOW THRU 18Z HOWEVER THEY
COULD EVENTUALLY BACK IN FM THE NE AND E BY MID TO LATE AFTN
ALTHOUGH NEITHER THE LATEST NAM OR HRRR EVER SHOW THEM AFFECTING THE
AIRPORT. FOR NOW WILL GO WITH A TEMPO GROUP AS CONFIDENCE IS NOT
VERY HIGH. MEANWHILE THERE IS A 10% CHANCE OF A FEW SNOW FLURRIES
THIS AFTN AS A WK TROUGH MOVES ACROSS. WINDS EARLY THIS MORNING
WILL BE LIGHT WLY AND THEN BECOME LIGHT SLY BY 15Z. BY EARLY AFTN
AS THE FNT BACKDOORS IN THE WINDS WILL BECOME LIGHT ESE BASED ON THE
LATEST HRRR.
FOR THIS EVENING COULD STILL SEE SOME POTENTIAL FOR LOW CLOUDS AND
FOG ALTHOUGH NAM KEEPS BEST CHC TO THE NORTH AND EAST OF AIRPORT.
AFTER 06Z THE LOW LEVEL WINDS BECOME MORE WSW WHICH SHOULD KEEP THE
LOW CLOUDS EAST OF THE AIRPORT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....ENTREKIN
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS DENVER CO
310 AM MST THU DEC 8 2011
SHORT TERM...A WK UPPER LEVEL TROUGH WILL MOVE SE ACROSS THE AREA
TODAY WITH SOME VERY WK MID LVL QG ASCENT. CROSS-SECTIONS SHOW
ENOUGH MOISTURE WILL BE AVAILABLE FOR A CHC OF SOME LIGHT SNOW IN
THE MTNS MAINLY OVER ZNS 31 AND 33. EAST OF THE MTNS A CDFNT WILL
MOVE ACROSS NERN CO LATER THIS MORNING THRU THE AFTN HOURS HOWEVER
UPSLOPE FLOW WILL BE WK. MEANWHILE THE FAR NERN PLAINS WILL ALSO BE
AFFECTED BY A WK UPPER LEVEL JET WHICH COULD LEAD TO A CHC OF LIGHT
SNOW THRU THE AFTN HOURS MAINLY FM STERLING EASTWARD. ELSEWHERE
ACROSS THE PLAINS THERE WILL ONLY BE A SLIGHT CHC OF -SHSN.
SOUNDINGS SHOW AIRMASS WILL BE COLD ENOUGH FOR PCPN TO FALL AS SNOW
SO WILL NOT MENTION ANY FREEZING DRIZZLE ACROSS NERN CO. HIGHS THIS
AFTN WILL GENERALLY BE IN THE 25 TO 30 DEGREE RANGE ACROSS NERN CO
BEHIND THE CDFNT AS COLD SFC HIGH PRESSURE BUILDS INTO THE RGN.
FOR TONIGHT WILL HAVE A DRY FCST AS THE WK UPPER LEVEL TROUGH MOVES
AWAY FM THE AREA. SOME FOG COULD DVLP OVER THE PLAINS THIS EVENING
AND LINGER OVERNIGHT.
.LONG TERM...THERE WILL BE A DECREASING NORTHWEST FLOW ALOFT ON
FRIDAY WITH A DRYING AND SLOW WARMING TREND ACROSS COLORADO. THIS
TREND WILL CONTINUE THROUGH THE WEEKEND AS THE GREAT BASIN RIDGE OF
HIGH PRESSURE SHIFTS OVER COLORADO AND WEAKENS A BIT. TEMPERATURES
WILL WARM TO AROUND SEASONABLE NORMALS WITH PLENTY OF SUNSHINE AND
DRY CONDITIONS.
BY EARLY NEXT WEEK...SPLIT FLOW PATTERN DEVELOPS OVER MUCH OF THE
WEST WITH CLOSED LOW DEVELOPING ACROSS SOUTHERN CALIFORNIA ON MONDAY
WHILE WEAKER NORTHERN BRANCH STRETCHES A WEAK TROF ACROSS THE
NORTHERN PLAINS STATES AND BRUSHES NORTHERN COLORADO WITH A WEAK
FRONT AND COOLER TEMPERATURES. THIS PATTERN EVOLUTION SHOWS QUITE A
BIT OF UNCERTAINTY AS THE EUROPEAN/GEM SOLUTIONS ARE DEEPER WITH THE
LOW YET EJECTS IT FURTHER NORTH INTO COLORADO ON WEDNESDAY WHILE THE
GFS SOLUTION HAS THE LOW ACROSS NEW MEXICO AND TEXAS. THE EUROPEAN
TRAJECTORY WOULD FAVOR A CHANCE OF SNOW AND COOLER TEMPS WHERE VERY
LITTLE EFFECT WOULD BE FELT FROM THE FURTHER SOUTH GFS SOLUTIONS.
GFS ENSEMBLE MEMBERS NOT MUCH HELP AS SOLUTIONS ARE ALL OVER THE
BOARD. THIS ALL MEANS VERY LITTLE CHANGES TO THE OUT DAYS IN THE
LONG TERM FORECAST. WILL KEEP A SLIGHT CHANCE OF SNOW OVER THE
ENTIRE CWA FOR LATE TUESDAY AND WEDNESDAY.
$$
AVIATION...A CDFNT WILL MOVE ACROSS NERN CO LATER THIS MORNING AND
AFTN HOWEVER BOTH THE NAM AND HRRR KEEP THE MAIN PUSH OVER THE
PLAINS AND KIND OF BACK DOOR THE FNT INTO THE FNT RANGE BY EARLY TO
MID AFTN WITH VERY WK UPSLOPE. OVERALL IT LOOKS LIKE POTENTIAL FOR
LOW CEILINGS AND SOME FOG WILL REMAIN LOW THRU 18Z HOWEVER THEY
COULD EVENTUALLY BACK IN FM THE NE AND E BY MID TO LATE AFTN
ALTHOUGH NEITHER THE LATEST NAM OR HRRR EVER SHOW THEM AFFECTING THE
AIRPORT. FOR NOW WILL GO WITH A TEMPO GROUP AS CONFIDENCE IS NOT
VERY HIGH. MEANWHILE THERE IS A 10% CHANCE OF A FEW SNOW FLURRIES
THIS AFTN AS A WK TROUGH MOVES ACROSS. WINDS EARLY THIS MORNING
WILL BE LIGHT WLY AND THEN BECOME LIGHT SLY BY 15Z. BY EARLY AFTN
AS THE FNT BACKDOORS IN THE WINDS WILL BECOME LIGHT ESE BASED ON THE
LATEST HRRR.
FOR THIS EVENING COULD STILL SEE SOME POTENTIAL FOR LOW CLOUDS AND
FOG ALTHOUGH NAM KEEPS BEST CHC TO THE NORTH AND EAST OF AIRPORT.
AFTER 06Z THE LOW LEVEL WINDS BECOME MORE WSW WHICH SHOULD KEEP THE
LOW CLOUDS EAST OF THE AIRPORT.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....SWE
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
952 AM EST THU DEC 8 2011
.UPDATE...WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW BROAD MID-
UPPER TROUGHING ACROSS THE SRN CONUS WITH UPPER LEVEL DISTURBANCE
MOVING ACROSS THE OK/TX/AR AREA. SHOULD SEE ASSOCD HIGH CLOUDS
MOVE ACROSS OUR AREA IN THE AFTERNOON AND TONIGHT.
SFC HIGH IS SITUATED ACROSS THE LOWER MS VALLEY TO ERN TN WITH
TYPICAL INVERTED TROUGHING NOTED ALONG OUR COAST. LLVL FLOW IS NLY
BUT JUST ABOVE THE SFC HAS TURNED NE. BROKEN-OVERCAST STRATOCU
CLOUDS AROUND 2-3 KFT HAVE ADVANCED WELL INLAND NOW TO DUVAL
COUNTY SW TO MARION COUNTY. THESE CLOUDS ASSOCD WITH COLDER
AIRMASS MOVING OVER WARM ATLC WATERS/WEAK ISENTROPIC LIFT AND
LLVL CONVERGENCE. HAVE ADJUSTED SKY CONDS UP TO MOSTLY CLOUDY AND
TWEAKED TEMPS DOWN OVER THE SE ZONES. A FEW SPRINKLES POSSIBLE
LATER IN THE AFTN NEAR THE COAST S OF DUVAL BUT THINK WILL LEAVE
OUT FOR NOW DUE TO SHALLOW NATURE OF THIS MOISTURE.
&&
.AVIATION...MVFR CIGS AROUND FL020-030 EXPECTED FOR JAX/CRG/VQQ
AND GNV FOR DURATION OF THE DAY AS STRATOCU MOVES INLAND. PROBABLY
LOOKING AT MVFR DEVELOPING AT SSI AROUND THE 16Z-18Z TIME FRAME SO
AMENDMENTS TO FOLLOW. OUTLOOK FOR TONIGHT CALLS FOR MVFR CIGS WITH
THE BEST CHANCES COASTAL COUNTY TAFS.
&&
.MARINE...NLY WINDS AT 15-20 KT AT 41012 WITH SEAS OF 5 FT. THIS
IS SLIGHTLY BELOW CURRENT WINDS SO WILL ADJUST WINDS A BIT DOWNWARD
REST OF TODAY BUT ADVISORY FOR OFFSHORE LOOKS GOOD...AND WINDS
ANTICIPATED TO BE AROUND THE 15-20KT RANGE NEARSHORE.
RIP CURRENTS: MODERATE RISK AS WINDS SHIFTING TO NE AND LOW E
SWELLS.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 59 35 63 42 / 0 0 10 10
SSI 58 47 64 49 / 0 10 10 20
JAX 60 44 67 47 / 0 10 10 10
SGJ 60 51 68 54 / 10 20 10 20
GNV 61 42 68 48 / 0 10 10 10
OCF 63 46 71 51 / 0 10 10 10
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ALTAMAHA
SOUND GA TO FERNANDINA BEACH FL 20 NM TO 60 NM OFFSHORE-
FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE-
ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE.
&&
$$
SHASHY/WALKER
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
640 AM EST THU DEC 8 2011
UPDATED AVIATION DISCUSSION FOR 12Z TAFS
.SYNOPSIS /ISSUED AT 545 AM/...
WV IMAGERY AND RUC ANALYSIS INDICATED CYCLONIC MID/UPPER LEVEL FLOW
AROUND A VORTEX OVER HUDSON BAY BRINGING NRN STREAM WNW FLOW FROM
SRN CANADA INTO THE UPPER GREAT LAKES. A SHORTWAVE MOVING THROUGH
THE UPPER GREAT LAKES EARLY THIS MORNING ALONG WITH ITS ASSOC SFC
TROUGH IS HELPING TO FOCUS AN INTENSE LAKE ENHANCED SNOW BAND OVER
SOUTH CENTRAL LAKE SUPERIOR AND THE ERN UPR MI SHORELINE IN THE PAST
HR AS NOTED ON RADAR IMAGERY. A STRONG 140 KT UPR JET MAX DIVING
DOWN THROUGH ALBERTA WILL HELP AMPLIFY MID-UPR LVL TROF OVER THE
UPPER GREAT LAKES LATE TONIGHT AND FRIDAY AS WELL AS POSSIBLY BRING
SOME ENHANCEMENT TO LES BANDS OVER LAKE SUPERIOR. ABUNDANT DRY AIR
UPSTREAM OVER THE NRN PLAINS AS NOTED ON SATELLITE IMAGERY AND SFC
OBS HAS THUS FAR INHIBITED ORGANIZATION OF LES BANDS OVER WRN LAKE
SUPERIOR DESPITE ADVECTION OF -15C 850 TEMPS INTO AREA.
&&
.DISCUSSION...
MAIN CONCERN IS LES POTENTIAL AND ONGOING HEADLINES OVER WRN UPR MI
INTO FRIDAY.
CONCERN TODAY WILL BE ABUNDANT DRY AIR UPSTREAM...WHICH IS DEPICTED
FAIRLY WELL BY GFS BUFR SNDGS...AND HOW MUCH THIS DRY AIR WILL
NEGATIVELY AFFECT ORGANIZATION OF LES BANDS AND THUS POTENTIAL FOR
HEAVY SNOW ACCUMULATION AT LEAST TODAY. ALL 00Z MODELS INCLUDING
LOCAL MESOSCALE MODELS ARE LESS BULLISH ON LAKE EFFECT QPF THAN PREV
RUNS AND AGAIN THIS IS LIKELY DUE TO DRIER AIR UPSTREAM OF THE LAKE
AND LACK OF SYNOPTIC SCALE FORCING. EVEN THOUGH SNOW GROWTH REMAINS
GENERALLY FAVORABLE WITH 25-30/1 SNOW WATER RATIOS
EXPECTED...GENERALLY DECIDED TO TRIM BACK LES ACCUMS TO 2 TO LOCALLY
5 INCHES OVER WARNING AND ADVISORY AREAS OF NRN ONTONAGON...HOUGHTON
AND KEWEENAW COUNTIES TODAY DUE TO IMPACTING DRY AIR. GUSTY WEST
WINDS TO 30 MPH WILL LIKELY CAUSE CONSIDERABLE BLOWING SNOW AND
REDUCED VSBYS IN ANY MODERATE LES BANDS THAT FORM OVER HEADLINE
REGIONS.
LOCATIONS NEAR LAKE SUPERIOR EAST OF MUNISING...FROM GRAND MARAIS TO
TWO HEART MAY ALSO SEE A PERIOD OF BRIEF HEAVY SNOW EARLY THIS
MORNING WITH BAND MOVING ACROSS ERN LAKE SUPERIOR ATTM. AS MENTIONED
BEFORE PLENTY OF UNCERTAINTY EXISTS WITH EVOLUTION OF LES BANDS
TODAY AND WHETHER ANY HEAVIER WILL MOVE INLAND OR OFFSHORE...SO NO
HEADLINES WERE ISSUED FOR ERN COUNTIES AT THIS TIME.
LARGE SCALE TROUGH WITH COLDEST AIR OF SEASON THUS FAR TO PUSH INTO
THE AREA TONIGHT INTO FRIDAY. MODELS NOT DEPICTING MUCH IN THE WAY
OF ANY SIGNIFICANT SHORTWAVES THAT WOULD AID IN ENHANCEMENT TO LES
BANDS. HOWEVER...COMBINATION OF POSSIBLE WEAK ENHANCEMENT WITH
ARRIVAL OF TROUGH...H85 TEMPS LOWERING TO AROUND -18C BY 12Z FRIDAY
AND INCREASING LOW-LVL CONVERGENCE FROM NIGHTTIME LAND BREEZES...MAY
BE JUST ENOUGH TO ORGANIZE FORMATION OF DOMINANT BAND OVER SRN LAKE
SUPERIOR AS DEPICTED BY 00Z MODELS. INTERESTINGLY ENOUGH...MODEL AVG
QPF NOT AS HEAVY AS PREV RUNS FOR TONIGHT INTO FRIDAY MORNING...AND
THIS IS AGAIN LIKELY TO DUE TO AFFECTS OF VERY DRY AIR UPSTREAM.
STILL WOULD EXPECT TOTAL SNOW ACCUMS TO EXCEED A FOOT AT FAVORED
HIGHER TERRIAN LOCATIONS THROUGH ENTIRE EVENT. WRN INTERIOR
LOCATIONS MAY DIP CLOSE TO ZERO TONIGHT WHILE HIGHS ON FRIDAY WILL
STAY MAINLY IN THE LOWER TEENS.
BY LATE FRIDAY...WEAKER TROUGH FCST TO SLIDE THROUGH THE AREA MAY
VEER WINDS SLIGHTLY MORE NW LEADING TO INCREASED CHANCES OF DOMINANT
LES BAND MOVING INTO FAR EASTERN SECTION OF CWA...MAINLY EAST OF
MUNISING AND WELL NORTH OF NEWBERRY. SOME MODERATE TO POSSIBLE HEAVY
SNOWFALL COULD WARRANT A HEADLINE AT SOME POINT FOR THESE COUNTIES.
TROUGH AND COLDER AIR SFC-H85 SLOWLY HEAD INTO LOWER GREAT LAKES
FRIDAY NIGHT INTO SATURDAY. WARM AIR ADVECTION STARTS UP BY SATURDAY
LEADING TO A PUSH OF ISENTROPIC ASCENT 285-290K (750-650MB) ACROSS
MUCH OF THE CWA...BUT LIMITED MOISTURE SHOULD KEEP CWA DRY. LES
BANDS WILL PUSH OFFSHORE BY LATE FRI NIGHT INTO EARLY SATURDAY AS
GUSTY SW WINDS LOWERS WIND CHILL VALUES IN THE MORNING DESPITE SFC
TEMPS REBOUNDING INTO LOWER TO MIDDLE 20S SAT AFTERNOON.
MODELS STILL IN AGREEMENT WITH SHORTWAVE AND PASSAGE OF FRONTAL
BOUNDARY BRINGING ANOTHER CHC OF SNOW..POSSIBLY MIXED WITH RAIN EAST
HALF ON MONDAY WITH SOME LINGERING LIGHT SNOW POSSIBLE MON NIGHT
INTO TUE.
&&
.AVIATION /FOR THE 12Z TAF ISSUANCE/...
A CONTINUED WESTERLY FLOW OF COLD AIR ACROSS THE WARM WATERS OF LAKE
SUPERIOR...AND INCREASED LIFT FROM THE TERRAIN ENHANCEMENT OF THE
KEWEENAW PENINSULA WILL AID IN KEEPING LAKE EFFECT SNOW SHOWERS IN
PLACE AT CMX. LIFR CEILINGS AND VIS WILL REMAIN
POSSIBLE...PARTICULARLY WITH BLSN THANKS TO GUSTY WINDS OVER 30KTS.
FARTHER TO THE SOUTH...A LESS FAVORABLE WIND DIRECTION AT IWD WILL
MAINLY RESULT IN A FEW FLAKES OF SNOW...AND HIGH END MVFR CEILINGS
AND VIS. SOME SNOW SHOWERS HAVE BEEN ABLE TO SLIDE TO SAW...BUT HAVE
REMAINED LIGHT AND SHELTERED SO FAR...WITH HIGH END MVFR POSSIBLE IN
THE HEAVIER BANDS THERE AS WELL AS MUCH OF THE SNOW REMAINS OFFSHORE.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
THE UPPER GREAT LAKES WILL REMAIN BETWEEN STRONG A LOW ACROSS HUDSON
BAY...AND STRONG HIGH PRESSURE OVER W CANADA AND THE NORTHERN PLAINS
THROUGH TONIGHT...WITH WESTERLY GALES TO 35KTS CONTINUING INTO THE
EVENING HOURS. EXPECT THE HIGH TO SLIDE TO THE CENTRAL PLAINS
OVERNIGHT...BEFORE SHIFTING TO THE OHIO VALLEY AND MID ATLANTIC THIS
WEEKEND. THE RESULT WILL BE A RIDGE SLIDING OVER THE UPPER GREAT
LAKES FRIDAY AND FRIDAY NIGHT...WEAKENING OVER THE WEEKEND. LOW
PRESSURE ACROSS SOUTH CENTRAL CANADA SUNDAY MORNING SHOULD SLOWLY
PUSH ACROSS LS AND MANITOBA MONDAY AFTERNOON THROUGH TUESDAY. OUT
AHEAD OF THIS LOW...STRONG SW WINDS AND POSSIBLY GALES TO 35KTS WILL
BE POSSIBLE SATURDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST FRIDAY FOR MIZ002-003.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ001-084.
LAKE SUPERIOR...
GALE WARNING UNTIL 1 AM EST FRIDAY FOR LSZ263>267.
GALE WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
LSZ241>244.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...VOSS
DISCUSSION...VOSS
AVIATION...KF
MARINE...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
624 AM EST THU DEC 8 2011
.SYNOPSIS /ISSUED AT 545 AM/...
WV IMAGERY AND RUC ANALYSIS INDICATED CYCLONIC MID/UPPER LEVEL FLOW
AROUND A VORTEX OVER HUDSON BAY BRINGING NRN STREAM WNW FLOW FROM
SRN CANADA INTO THE UPPER GREAT LAKES. A SHORTWAVE MOVING THROUGH
THE UPPER GREAT LAKES EARLY THIS MORNING ALONG WITH ITS ASSOC SFC
TROUGH IS HELPING TO FOCUS AN INTENSE LAKE ENHANCED SNOW BAND OVER
SOUTH CENTRAL LAKE SUPERIOR AND THE ERN UPR MI SHORELINE IN THE PAST
HR AS NOTED ON RADAR IMAGERY. A STRONG 140 KT UPR JET MAX DIVING
DOWN THROUGH ALBERTA WILL HELP AMPLIFY MID-UPR LVL TROF OVER THE
UPPER GREAT LAKES LATE TONIGHT AND FRIDAY AS WELL AS POSSIBLY BRING
SOME ENHANCEMENT TO LES BANDS OVER LAKE SUPERIOR. ABUNDANT DRY AIR
UPSTREAM OVER THE NRN PLAINS AS NOTED ON SATELLITE IMAGERY AND SFC
OBS HAS THUS FAR INHIBITED ORGANIZATION OF LES BANDS OVER WRN LAKE
SUPERIOR DESPITE ADVECTION OF -15C 850 TEMPS INTO AREA.
&&
.DISCUSSION...
MAIN CONCERN IS LES POTENTIAL AND ONGOING HEADLINES OVER WRN UPR MI
INTO FRIDAY.
CONCERN TODAY WILL BE ABUNDANT DRY AIR UPSTREAM...WHICH IS DEPICTED
FAIRLY WELL BY GFS BUFR SNDGS...AND HOW MUCH THIS DRY AIR WILL
NEGATIVELY AFFECT ORGANIZATION OF LES BANDS AND THUS POTENTIAL FOR
HEAVY SNOW ACCUMULATION AT LEAST TODAY. ALL 00Z MODELS INCLUDING
LOCAL MESOSCALE MODELS ARE LESS BULLISH ON LAKE EFFECT QPF THAN PREV
RUNS AND AGAIN THIS IS LIKELY DUE TO DRIER AIR UPSTREAM OF THE LAKE
AND LACK OF SYNOPTIC SCALE FORCING. EVEN THOUGH SNOW GROWTH REMAINS
GENERALLY FAVORABLE WITH 25-30/1 SNOW WATER RATIOS
EXPECTED...GENERALLY DECIDED TO TRIM BACK LES ACCUMS TO 2 TO LOCALLY
5 INCHES OVER WARNING AND ADVISORY AREAS OF NRN ONTONAGON...HOUGHTON
AND KEWEENAW COUNTIES TODAY DUE TO IMPACTING DRY AIR. GUSTY WEST
WINDS TO 30 MPH WILL LIKELY CAUSE CONSIDERABLE BLOWING SNOW AND
REDUCED VSBYS IN ANY MODERATE LES BANDS THAT FORM OVER HEADLINE
REGIONS.
LOCATIONS NEAR LAKE SUPERIOR EAST OF MUNISING...FROM GRAND MARAIS TO
TWO HEART MAY ALSO SEE A PERIOD OF BRIEF HEAVY SNOW EARLY THIS
MORNING WITH BAND MOVING ACROSS ERN LAKE SUPERIOR ATTM. AS MENTIONED
BEFORE PLENTY OF UNCERTAINTY EXISTS WITH EVOLUTION OF LES BANDS
TODAY AND WHETHER ANY HEAVIER WILL MOVE INLAND OR OFFSHORE...SO NO
HEADLINES WERE ISSUED FOR ERN COUNTIES AT THIS TIME.
LARGE SCALE TROUGH WITH COLDEST AIR OF SEASON THUS FAR TO PUSH INTO
THE AREA TONIGHT INTO FRIDAY. MODELS NOT DEPICTING MUCH IN THE WAY
OF ANY SIGNIFICANT SHORTWAVES THAT WOULD AID IN ENHANCEMENT TO LES
BANDS. HOWEVER...COMBINATION OF POSSIBLE WEAK ENHANCEMENT WITH
ARRIVAL OF TROUGH...H85 TEMPS LOWERING TO AROUND -18C BY 12Z FRIDAY
AND INCREASING LOW-LVL CONVERGENCE FROM NIGHTTIME LAND BREEZES...MAY
BE JUST ENOUGH TO ORGANIZE FORMATION OF DOMINANT BAND OVER SRN LAKE
SUPERIOR AS DEPICTED BY 00Z MODELS. INTERESTINGLY ENOUGH...MODEL AVG
QPF NOT AS HEAVY AS PREV RUNS FOR TONIGHT INTO FRIDAY MORNING...AND
THIS IS AGAIN LIKELY TO DUE TO AFFECTS OF VERY DRY AIR UPSTREAM.
STILL WOULD EXPECT TOTAL SNOW ACCUMS TO EXCEED A FOOT AT FAVORED
HIGHER TERRIAN LOCATIONS THROUGH ENTIRE EVENT. WRN INTERIOR
LOCATIONS MAY DIP CLOSE TO ZERO TONIGHT WHILE HIGHS ON FRIDAY WILL
STAY MAINLY IN THE LOWER TEENS.
BY LATE FRIDAY...WEAKER TROUGH FCST TO SLIDE THROUGH THE AREA MAY
VEER WINDS SLIGHTLY MORE NW LEADING TO INCREASED CHANCES OF DOMINANT
LES BAND MOVING INTO FAR EASTERN SECTION OF CWA...MAINLY EAST OF
MUNISING AND WELL NORTH OF NEWBERRY. SOME MODERATE TO POSSIBLE HEAVY
SNOWFALL COULD WARRANT A HEADLINE AT SOME POINT FOR THESE COUNTIES.
TROUGH AND COLDER AIR SFC-H85 SLOWLY HEAD INTO LOWER GREAT LAKES
FRIDAY NIGHT INTO SATURDAY. WARM AIR ADVECTION STARTS UP BY SATURDAY
LEADING TO A PUSH OF ISENTROPIC ASCENT 285-290K (750-650MB) ACROSS
MUCH OF THE CWA...BUT LIMITED MOISTURE SHOULD KEEP CWA DRY. LES
BANDS WILL PUSH OFFSHORE BY LATE FRI NIGHT INTO EARLY SATURDAY AS
GUSTY SW WINDS LOWERS WIND CHILL VALUES IN THE MORNING DESPITE SFC
TEMPS REBOUNDING INTO LOWER TO MIDDLE 20S SAT AFTERNOON.
MODELS STILL IN AGREEMENT WITH SHORTWAVE AND PASSAGE OF FRONTAL
BOUNDARY BRINGING ANOTHER CHC OF SNOW..POSSIBLY MIXED WITH RAIN EAST
HALF ON MONDAY WITH SOME LINGERING LIGHT SNOW POSSIBLE MON NIGHT
INTO TUE.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
PASSAGE OF THE FIRST IN A SERIES OF LO PRES TROF WL BRING IFR
CONDITIONS TO THE EXPOSED CMX LOCATION THAT WL EXPERIENCE MORE SGNFT
LK MOISTENING DESTABILIZATION EARLY THIS MRNG. ALTHOUGH THERE MAY BE
SOME -SHSN AT IWD AND SAW...ANY REDUCED CIG/VSBY WL BE MORE LIMITED
WITH LESS LK MODIFICATION AND/OR DOWNSLOPE WIND COMPONENT. EXPECT A
PERIOD OF IMPROVEMENT TOWARD SUNRISE AS A TRAILING SFC HI PRES
RDG/AXIS OF DRIER AIR FOLLOWING THE TROF SHIFTS OVHD. BUT THE LULL
WL BE ONLY TEMPORARY WITH A SECOND LO PRES TROF FOLLOWING THRU AT
MID MRNG. THIS DEEPER TROF WL BE FOLLOWED BY STRONGER W WINDS THAT
WL CAUSE GUSTS AS HI AS 30 KT OVER THE EXPOSED KEWEENAW/CMX. THE
COMBINATION OF FALLING LK EFFECT SN AND BLSN WHIPPED UP BY THESE
STRONG WINDS WL LIKELY LEAD TO LIFR CONDITIONS AT THAT SITE. THE DRY
NATURE OF THE ARCTIC AIRMASSES WL LIMIT DETERIORATION AT IWD AND
ESPECIALLY SAW...WHERE THE PREVAILING WLY WIND COMPONENT WL
DOWNSLOPE/DRY AND RESULT IN PREDOMINANT VFR CONDITIONS.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
THE UPPER GREAT LAKES WILL REMAIN BETWEEN STRONG A LOW ACROSS HUDSON
BAY...AND STRONG HIGH PRESSURE OVER W CANADA AND THE NORTHERN PLAINS
THROUGH TONIGHT...WITH WESTERLY GALES TO 35KTS CONTINUING INTO THE
EVENING HOURS. EXPECT THE HIGH TO SLIDE TO THE CENTRAL PLAINS
OVERNIGHT...BEFORE SHIFTING TO THE OHIO VALLEY AND MID ATLANTIC THIS
WEEKEND. THE RESULT WILL BE A RIDGE SLIDING OVER THE UPPER GREAT
LAKES FRIDAY AND FRIDAY NIGHT...WEAKENING OVER THE WEEKEND. LOW
PRESSURE ACROSS SOUTH CENTRAL CANADA SUNDAY MORNING SHOULD SLOWLY
PUSH ACROSS LS AND MANITOBA MONDAY AFTERNOON THROUGH TUESDAY. OUT
AHEAD OF THIS LOW...STRONG SW WINDS AND POSSIBLY GALES TO 35KTS WILL
BE POSSIBLE SATURDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST FRIDAY FOR MIZ002-003.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ001-084.
LAKE SUPERIOR...
GALE WARNING UNTIL 1 AM EST FRIDAY FOR LSZ263>267.
GALE WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
LSZ241>244.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...VOSS
DISCUSSION...VOSS
AVIATION...KF
MARINE...KF
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
545 AM EST THU DEC 8 2011
.SYNOPSIS...
HIGH PRESSURE THURSDAY. COLD FRONT FRIDAY NIGHT. HIGH PRESSURE
FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
600AM UPDATE...
FORECAST REMAINS LARGELY ON TRACK. UPDATE INSERTED FOR CLOUD DECK
CONTINUING TO LINGER IN THE NORTHERN MOUNTAINS EARLY THIS MORNING.
PREVIOUS DISCUSSION...
CLEARING ACROSS THE LOWLANDS HAS RESULTED IN STRONG RADIATIONAL
COOLING. STILL EXPECTING TEMPS TO CRASH THROUGH EARLY MORNING HOURS.
CLEARING HAS STALLED A BIT IN THE MOUNTAINS WHERE EKN AND BKW STILL
REPORTING BKN CLOUD COVER. EXPECTING THESE SITES TO CLEAR OUT
COMPLETELY BY 10Z.
CURRENT IR SATELLITE IMAGERY SHOWS SHALLOW CLOUD DECK KNOCKING ON
THE DOORSTEPS OF OUR SE OHIO COUNTIES. LATEST RUN OF THE RUC HAS
THIS FEATURE DIAGNOSED WELL WITH COINCIDING 850MB MOISTURE MOVING
ACROSS OUR NORTHERN TIER COUNTIES AND SLOSHING UP AGAINST THE HIGH
TERRAIN OF THE NE MNT COUNTIES. RESULTANT RUC SOUNDINGS DISPLAYED IN
BUFKIT TRYING TO DEVELOP LOW STRATUS AGAINST THE MOUNTAINS AROUND
12Z. NOT COMPLETELY SOLD ON THIS AS RUC 850MB MOISTURE SHOULD ERODE
FURTHER DOWNSTREAM OF THE SOUTHERN GREAT LAKES. ALSO...WARMING TREND
IN 850MB TEMPS SHOULD HELP TO DRY THE COLUMN FURTHER. ALL
TOLD...WILL NOT INCLUDE STRATUS DEVELOPMENT IN THIS PACKAGE...BUT
WILL CONTINUE TO MONITOR FORTHCOMING GUIDANCE AND TRENDS.
A CHANGE OF PACE TODAY...RELATIVE TO THE LAST FEW DAYS. SUNNY SKIES
WITH COLDER TEMPERATURES ARE EXPECTED AS CWA IS NOW UNDER THE
CONTROL OF A SURFACE HIGH.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
NEXT SYSTEM TO DEAL WITH WILL BE A MOISTURE STARVED COLD FRONT
EXPECTED TO ENTER THE SOUTHEAST OHIO ZONES AFTER 18Z FRIDAY. SREF
PROBABILITIES OF ACCUMULATING PRECIPITATION ARE ON THE LOW
SIDE...BELOW 50 PERCENT...AND WILL HAVE A TOUGH TIME SATURATING
ABOVE ABOUT 750MB. THAT BEING SAID...SNOW SHOWERS ARE POSSIBLE UPON
PASSAGE...LIKELY NOT ACCUMULATING OR GIVING TRACE ACCUMULATIONS.
OF MORE SIGNIFICANCE IS THE AIRMASS BEHIND THE COLD FRONT. 500MB
HEIGHTS DROP IN THE POST FRONTAL TROUGH...AND 850MB TEMPERATURES
ALSO DECREASE INTO THE MINUS TEENS COME SATURDAY. THERMAL TROUGH AT
THIS LEVEL WILL PERSIST OVER THE NORTHEAST MOUNTAINS...AND WITH A
CLEARING SKY...SATURDAY NIGHT TEMPERATURES LOOK VERY COLD. STRONG
HIGH PRESSURE SETTLES IN OVER THE REMAINDER OF THE WEEKEND IN A
LARGELY DRY PATTERN THROUGH EARLY NEXT WEEK.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
A BREAK FROM ANY RAIN OR SNOW WILL OCCUR DURING THE FIRST SEVERAL
DAYS OF THIS PERIOD. A POCKET OF COLD AIR WILL BE IN PLACE THANKS TO
SURFACE HIGH PRESSURE. AS THE SURFACE HIGH PRESSURE SLIDES
NORTHEAST...POCKET OF COLDEST TEMPERATURES WILL ALSO FOLLOW. SUNDAY
THROUGH TUESDAY WILL FEATURE MOSTLY SUNNY SKIES DURING THE DAY AND
CLEAR AND COLD AT NIGHT. THE NEXT SYSTEM WILL APPROACH THE AREA
DURING THE MID WEEK. WILL CONTINUE TO MONITOR THE SYSTEM AS IT
DEVELOPS.
GENERALLY FOLLOWED HPC GUIDANCE WITH ONLY A FEW MODIFICATION.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
MVFR CONDITIONS LINGERING IN CKB AND EKN FOR CIGS WITH RESIDUAL
CLOUD DECK THAT IS RELUCTANT TO ERODE.
CLEAR SKY OVER THE LOWLANDS RESULTING IN VFR...EXPECTING ALL SITES
VFR AFTER 14Z.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z FRIDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: CLOUD DECK OVER CKB AND EKN COULD BECOME MORE
PERSISTENT...LASTING BEYOND 14Z.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
EST 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY M M M M M M H H H H H H
PKB CONSISTENCY H M M H H H H H H H H H
CKB CONSISTENCY M M M M M M H H H H H H
AFTER 12Z FRIDAY...
NO WIDESPREAD IFR EXPECTED.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...26/TAX
NEAR TERM...TAX
SHORT TERM...26
LONG TERM...JB
AVIATION...TAX
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1231 PM EST THU DEC 8 2011
UPDATED AVIATION DISCUSSION FOR 18Z TAFS
.SYNOPSIS /ISSUED AT 545 AM/...
WV IMAGERY AND RUC ANALYSIS INDICATED CYCLONIC MID/UPPER LEVEL FLOW
AROUND A VORTEX OVER HUDSON BAY BRINGING NRN STREAM WNW FLOW FROM
SRN CANADA INTO THE UPPER GREAT LAKES. A SHORTWAVE MOVING THROUGH
THE UPPER GREAT LAKES EARLY THIS MORNING ALONG WITH ITS ASSOC SFC
TROUGH IS HELPING TO FOCUS AN INTENSE LAKE ENHANCED SNOW BAND OVER
SOUTH CENTRAL LAKE SUPERIOR AND THE ERN UPR MI SHORELINE IN THE PAST
HR AS NOTED ON RADAR IMAGERY. A STRONG 140 KT UPR JET MAX DIVING
DOWN THROUGH ALBERTA WILL HELP AMPLIFY MID-UPR LVL TROF OVER THE
UPPER GREAT LAKES LATE TONIGHT AND FRIDAY AS WELL AS POSSIBLY BRING
SOME ENHANCEMENT TO LES BANDS OVER LAKE SUPERIOR. ABUNDANT DRY AIR
UPSTREAM OVER THE NRN PLAINS AS NOTED ON SATELLITE IMAGERY AND SFC
OBS HAS THUS FAR INHIBITED ORGANIZATION OF LES BANDS OVER WRN LAKE
SUPERIOR DESPITE ADVECTION OF -15C 850 TEMPS INTO AREA.
&&
.DISCUSSION...
MAIN CONCERN IS LES POTENTIAL AND ONGOING HEADLINES OVER WRN UPR MI
INTO FRIDAY.
CONCERN TODAY WILL BE ABUNDANT DRY AIR UPSTREAM...WHICH IS DEPICTED
FAIRLY WELL BY GFS BUFR SNDGS...AND HOW MUCH THIS DRY AIR WILL
NEGATIVELY AFFECT ORGANIZATION OF LES BANDS AND THUS POTENTIAL FOR
HEAVY SNOW ACCUMULATION AT LEAST TODAY. ALL 00Z MODELS INCLUDING
LOCAL MESOSCALE MODELS ARE LESS BULLISH ON LAKE EFFECT QPF THAN PREV
RUNS AND AGAIN THIS IS LIKELY DUE TO DRIER AIR UPSTREAM OF THE LAKE
AND LACK OF SYNOPTIC SCALE FORCING. EVEN THOUGH SNOW GROWTH REMAINS
GENERALLY FAVORABLE WITH 25-30/1 SNOW WATER RATIOS
EXPECTED...GENERALLY DECIDED TO TRIM BACK LES ACCUMS TO 2 TO LOCALLY
5 INCHES OVER WARNING AND ADVISORY AREAS OF NRN ONTONAGON...HOUGHTON
AND KEWEENAW COUNTIES TODAY DUE TO IMPACTING DRY AIR. GUSTY WEST
WINDS TO 30 MPH WILL LIKELY CAUSE CONSIDERABLE BLOWING SNOW AND
REDUCED VSBYS IN ANY MODERATE LES BANDS THAT FORM OVER HEADLINE
REGIONS.
LOCATIONS NEAR LAKE SUPERIOR EAST OF MUNISING...FROM GRAND MARAIS TO
TWO HEART MAY ALSO SEE A PERIOD OF BRIEF HEAVY SNOW EARLY THIS
MORNING WITH BAND MOVING ACROSS ERN LAKE SUPERIOR ATTM. AS MENTIONED
BEFORE PLENTY OF UNCERTAINTY EXISTS WITH EVOLUTION OF LES BANDS
TODAY AND WHETHER ANY HEAVIER WILL MOVE INLAND OR OFFSHORE...SO NO
HEADLINES WERE ISSUED FOR ERN COUNTIES AT THIS TIME.
LARGE SCALE TROUGH WITH COLDEST AIR OF SEASON THUS FAR TO PUSH INTO
THE AREA TONIGHT INTO FRIDAY. MODELS NOT DEPICTING MUCH IN THE WAY
OF ANY SIGNIFICANT SHORTWAVES THAT WOULD AID IN ENHANCEMENT TO LES
BANDS. HOWEVER...COMBINATION OF POSSIBLE WEAK ENHANCEMENT WITH
ARRIVAL OF TROUGH...H85 TEMPS LOWERING TO AROUND -18C BY 12Z FRIDAY
AND INCREASING LOW-LVL CONVERGENCE FROM NIGHTTIME LAND BREEZES...MAY
BE JUST ENOUGH TO ORGANIZE FORMATION OF DOMINANT BAND OVER SRN LAKE
SUPERIOR AS DEPICTED BY 00Z MODELS. INTERESTINGLY ENOUGH...MODEL AVG
QPF NOT AS HEAVY AS PREV RUNS FOR TONIGHT INTO FRIDAY MORNING...AND
THIS IS AGAIN LIKELY TO DUE TO AFFECTS OF VERY DRY AIR UPSTREAM.
STILL WOULD EXPECT TOTAL SNOW ACCUMS TO EXCEED A FOOT AT FAVORED
HIGHER TERRIAN LOCATIONS THROUGH ENTIRE EVENT. WRN INTERIOR
LOCATIONS MAY DIP CLOSE TO ZERO TONIGHT WHILE HIGHS ON FRIDAY WILL
STAY MAINLY IN THE LOWER TEENS.
BY LATE FRIDAY...WEAKER TROUGH FCST TO SLIDE THROUGH THE AREA MAY
VEER WINDS SLIGHTLY MORE NW LEADING TO INCREASED CHANCES OF DOMINANT
LES BAND MOVING INTO FAR EASTERN SECTION OF CWA...MAINLY EAST OF
MUNISING AND WELL NORTH OF NEWBERRY. SOME MODERATE TO POSSIBLE HEAVY
SNOWFALL COULD WARRANT A HEADLINE AT SOME POINT FOR THESE COUNTIES.
TROUGH AND COLDER AIR SFC-H85 SLOWLY HEAD INTO LOWER GREAT LAKES
FRIDAY NIGHT INTO SATURDAY. WARM AIR ADVECTION STARTS UP BY SATURDAY
LEADING TO A PUSH OF ISENTROPIC ASCENT 285-290K (750-650MB) ACROSS
MUCH OF THE CWA...BUT LIMITED MOISTURE SHOULD KEEP CWA DRY. LES
BANDS WILL PUSH OFFSHORE BY LATE FRI NIGHT INTO EARLY SATURDAY AS
GUSTY SW WINDS LOWERS WIND CHILL VALUES IN THE MORNING DESPITE SFC
TEMPS REBOUNDING INTO LOWER TO MIDDLE 20S SAT AFTERNOON.
MODELS STILL IN AGREEMENT WITH SHORTWAVE AND PASSAGE OF FRONTAL
BOUNDARY BRINGING ANOTHER CHC OF SNOW..POSSIBLY MIXED WITH RAIN EAST
HALF ON MONDAY WITH SOME LINGERING LIGHT SNOW POSSIBLE MON NIGHT
INTO TUE.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/...
A CONTINUED WESTERLY FLOW OF COLD AIR ACROSS THE WARM WATERS OF LAKE
SUPERIOR...AND INCREASED LIFT FROM THE TERRAIN ENHANCEMENT OF THE
KEWEENAW PENINSULA WILL AID IN KEEPING LAKE EFFECT SNOW SHOWERS IN
PLACE AT CMX. LIFR TO VLIFR VIS WILL REMAIN POSSIBLE...PARTICULARLY
WITH BLSN THANKS TO GUSTY WINDS OVER 30KTS. FARTHER TO THE SOUTH...A
LESS FAVORABLE WIND DIRECTION AT IWD WILL MAINLY RESULT IN A FEW
FLAKES OF SNOW...AND HIGH END MVFR CEILINGS AND VIS. SOME SNOW
SHOWERS MAY BE ABLE TO SLIDE TO SAW LATER TODAY AND TONIGHT...BUT
WILL REMAIN LIGHT...WITH HIGH END MVFR POSSIBLE IN THE HEAVIER BANDS
THERE. KEPT ANY SNOW OUT OF THE TAF AT SAW AS MUCH OF THE SNOW WILL
REMAIN OFFSHORE.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
THE UPPER GREAT LAKES WILL REMAIN BETWEEN STRONG A LOW ACROSS HUDSON
BAY...AND STRONG HIGH PRESSURE OVER W CANADA AND THE NORTHERN PLAINS
THROUGH TONIGHT...WITH WESTERLY GALES TO 35KTS CONTINUING INTO THE
EVENING HOURS. EXPECT THE HIGH TO SLIDE TO THE CENTRAL PLAINS
OVERNIGHT...BEFORE SHIFTING TO THE OHIO VALLEY AND MID ATLANTIC THIS
WEEKEND. THE RESULT WILL BE A RIDGE SLIDING OVER THE UPPER GREAT
LAKES FRIDAY AND FRIDAY NIGHT...WEAKENING OVER THE WEEKEND. LOW
PRESSURE ACROSS SOUTH CENTRAL CANADA SUNDAY MORNING SHOULD SLOWLY
PUSH ACROSS LS AND MANITOBA MONDAY AFTERNOON THROUGH TUESDAY. OUT
AHEAD OF THIS LOW...STRONG SW WINDS AND POSSIBLY GALES TO 35KTS WILL
BE POSSIBLE SATURDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST FRIDAY FOR MIZ002-003.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST FRIDAY FOR MIZ001-084.
LAKE SUPERIOR...
GALE WARNING UNTIL 1 AM EST FRIDAY FOR LSZ263>267.
GALE WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR
LSZ241>244.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...VOSS
DISCUSSION...VOSS
AVIATION...TITUS
MARINE...KF
AREA FORECAST DISCUSSION
NWS GLASGOW MT
249 PM MST THU DEC 8 2011
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SATURDAY...
WATER VAPOR IMAGERY AND 500 MB HEIGHT FIELD SHOWING THE VERY
STRONG AND CLOSED UPPER LOW CENTER OVER HUDSON BAY AND ITS
ASSOCIATED LARGE SCALE UPPER TROUGH SPREADING OVER A LARGE
PORTION OF THE NORTH AMERICAN CONTINENT. JUST RECENTLY THIS
AFTERNOON THE BASE OF THE STRONGER PORTION OF THE LARGE TROUGH HAS
TAKEN ON A STRANGE SQUARISH SHAPE. VERY SLIGHT LARGE SCALE
TROUGHING IS ALSO PRESENT IN THE SOUTHERN STREAM ACROSS THE
SOUTHERN U.S. STATES. AN UPPER LEVEL RIDGE AND ITS ASSOCIATED
AREA OF HIGH PRESSURE IS GAINING STRENGTH JUST OF THE PACIFIC
NORTHWEST COAST.
LOCALLY...CLOUDS QUICKLY FORMED OVER THE CWA TODAY RIGHT ALONG THE
SURFACE RIDGE AXIS WITH CLEARER SKIES OFF TO THE NORTHEAST AND
CLOUDY SKIES CENTRAL AND SOUTHWEST. ENOUGH ASCENT IS PRESENT TO
SET OFF SOME VERY LIGHT VIRGA AND MAYBE SOME FLURRIES AS IS
EVIDENCED BY THE LIGHT RADAR REFLECTIVITIES TODAY. THE HRRR MODEL
HAS BEEN VERY ACCURATE IN DEPICTING THIS ACTIVITY WHEREAS THE
OTHER OPERATIONAL MODEL SOLUTIONS DID NOT BOTHER MUCH WITH IT.
TRIED TO FOLLOW THE TREND OF THIS HRRR MODEL FOR THE VERY NEAR
SHORT TERM THROUGH TONIGHT AS FLURRIES SHIFT SOUTHWEST AND
DIMINISH SOUTHWARD. ALSO...TONIGHT...WIND CHILL VALUES WILL
APPROACH 20 BELOW ZERO AGAIN ESPECIALLY OVER OUR FAR NORTHEAST
ZONES. BUT WITH WINDS FORECASTED BELOW 10 MPH...FELT IT WAS
SUFFICIENT TO ONLY MENTION IT IN THE HWO.
BEGINNING FRIDAY...THE ARCTIC AIR MASS AND HUDSON BAY LOW QUICKLY
GIVE WAY TO THE APPROACHING HIGH PRESSURE AND WARMER TEMPERATURES
FROM THE WEST. HIGHS SHOULD REBOUND EASILY INTO THE MID 20S
CENTRAL AND WELL ABOVE FREEZING OVER OUR SOUTHWESTERN ZONES.
ANOTHER PERIOD OF CLOUDINESS WILL SWEEP OVER NORTHEAST MONTANA ON
FRIDAY BUT I EXPECT ANY PRECIPITATION TO REMAIN WELL NORTH OF THE
INTERNATIONAL BOARDER. TRIED TO SHOW THE TREND WITH SOME SILENT
POPS AND SKY COVER.
SATURDAY...THE UPPER RIDGE FLATTENS SOMEWHAT BUT STILL MANAGES TO
MAKE SIGNIFICANT INROADS INTO OUR AREA...BRINGING TEMPERATURES
ABOVE FREEZING TO ALL OF NORTHEAST MONTANA EXCEPT THE FAR NORTHEAST
LITTLE CORNER. MOSTLY CLEAR SKIES AND NO PRECIPITATION TO START
THE WEEKEND. BMICKELSON
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
MADE SOME INCREASES WITH POPS FOR SUNDAY NIGHT AND ESPECIALLY
MONDAY. A SYSTEM LOOKS STRONGER WITH SOME OF THE MODELS AND
CONSISTENT ON THE ECMWF. ALSO RAISED POPS SLIGHTLY NEAR THE END OF
THE PERIOD CLOSER TO CLIMATOLOGY WITH AN UPPER TROUGH IN THE
WESTERN STATES. REST OF FORECAST LOOKED GOOD. JAMBA
PREVIOUS DISCUSSION...
THE EXTENDED PERIOD FEATURES A SERIES OF SHORTWAVE TROUGHS AND
RIDGES IN A PROGRESSIVE PATTERN. LIMITED MOISTURE WITH EACH OF THE
WEATHER SYSTEMS WILL LIMIT PRECIP CHANCES. TEMPERATURES WILL BE
WITHIN 10 DEGREES OF NORMAL DURING THE WHOLE PERIOD.
AN UPPER RIDGE MOVES TO THE EAST SATURDAY NIGHT AND SUNDAY WITH AN
UPPER TROUGH MOVING THROUGH EASTERN MONTANA ON MONDAY. THIS WILL
BRING A DRY COLD FRONT ACROSS THE AREA ON SUNDAY. LOOK FOR
SOMEWHAT COLDER AIR SUNDAY NIGHT AND MONDAY.
SHORTWAVE RIDGE FOLLOWS ON TUESDAY. ECMWF CURRENTLY WARMER THAN
THE GFS WITH THE TEMPERATURES. WILL FORECAST ON THE COLDER SIDE OF
THE POSSIBILITIES FOR NOW GIVEN THAT LIGHT WINDS SHOULD LEAD TO
POOR MIXING WITH LOW LEVEL INVERSIONS TRAPPING COLD AIR AT THE
SURFACE.
ANOTHER SHORTWAVE TROUGH MOVES THROUGH THE AREA WEDNESDAY AND THURSDAY
WITH ANOTHER DRY COLD FRONT AND SOMEWHAT COLDER AIR. FORRESTER
&&
.AVIATION...
CLOUDS AND ANY FLURRIES WILL EXIT TO THE SOUTHEAST THIS EVENING. A
WARM FRONT THEN MOVES EAST ACROSS THE AREA FRIDAY BUT LITTLE OR
NO FLURRIES ARE EXPECTED. WINDS ARE TO REMAIN LIGHT THROUGH THE
PERIOD. MVFR CONDITIONS ARE POSSIBLE WITH THE FLURRIES...BUT VFR
IS GENERALLY EXPECTED. JAMBA
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION...UPDATED
NWS GLASGOW MT
940 AM MST THU DEC 8 2011
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SATURDAY...
UPDATED THE FORECAST TODAY TO TRY TO GET AHEAD OF SOME POSSIBLE
FLURRIES INDICATED BY THE HRRR MODEL FOR THIS AFTERNOON AND
EVENING. SINCE THAT MODEL WAS THE ONLY CORRECT MODEL FOR
YESTERDAYS SNOWFALL...TRYING TO LEAN A LITTLE MORE IN THAT
DIRECTION. OTHER MODELS INDICATING AN INCREASE IN CLOUDINESS AS
WELL...SO I BUMPED UP POPS A BIT AND PUT IN SOME FLURRIES FOR THE
IMMEDIATE SHORT TERM. BMICKELSON
PREVIOUS SHORT TERM DISCUSSION...MASSIVE HUDSON BAY LOW PRESSURE
SYSTEM RESULTING IN A STRONG NW FLOW ALOFT WITH STEADY COLD
ADVECTION FOR NE MT. THIS MORNINGS LOWS RUNNING 20F COLDER THAN
YESTERDAY...AND HIGHS WILL BE AROUND 15F COLDER THAN
YESTERDAY...AS THE COLD AIR ADVECTION ENDS THIS AFTERNOON. THIS
ASSOCIATED WITH A POLAR SURFACE HIGH FROM NW CANADA THAT CALVED
OFF MOVING SE ACROSS THE ROCKIES YESTERDAY...ONE CENTER NOW OVER
SE AB/NC MT. THIS CENTER WILL BE OVER E MT THIS AFTERNOON AND
EVENING.
SATELLITE PICTURES SHOW A BAND OF MID-LEVEL OVERCAST ALIGNED
ALONG THE STRONG NW JET IN A SLIGHTLY CYCLONIC FLOW. THIS COVERS
ROUGHLY SW THIRD OF OUR CWA...NOT MOVING MUCH...BUT IT IS SHALLOW
AND SHOULD GRADUALLY BREAK UP AS THE DAY GOES ON. REST OF FORECAST
AREA IS CLEAR.
CLOSED UPPER HIGH ALONG PACIFIC COAST MOVES ACROSS THE INLAND WEST
AND WEAKENS FRI/SAT. THIS BRINGS MUCH WARMER AIR ALOFT TO OUR AREA
FRIDAY. SURFACE PRESSURE GRADIENTS ARE WEAK AND FORECAST SOUNDINGS
SHOW SURFACE-BASED INVERSION REMAINING ALL DAY. ALTHOUGH NOT
GREAT...THERE WILL ALSO BE A SIGNIFICANT SNOW COVER EFFECT AND MOST
OF THE CWA HAS AN INCH OR TWO ON GROUND. THE OTHER NEGATIVE FOR
FRIDAY IS THERE WILL BE MOSTLY CLOUDY SKIES HOLDING THE COLDER AIR
IN MORE. THIS IS WARM ADVECTION MID/HIGH CLOUDS...AND WE WILL BE ON
THE COLD SIDE OF THE RIDGE TOO. MOS LOOKS REASONABLE...BUT WILL GO ON
THE COLD SIDE FOR THE LOWER MILK/LOWER MISSOURI RIVER VALLEYS.
FURTHER WARMING ALOFT FOR SAT...THICKNESSES WELL INTO THE 540S
DM. 850 MB TEMPS CLIMB TO AS HIGH AS 7C. WEAK PRESSURE PATTERN
SIMILAR TO FRI THOUGH. HOWEVER SAT SHOULD HAVE FULL SUNSHINE
EFFECT AND THE RIDGE WILL WEAKEN TO A MODERATE WESTERLY FLOW
FAVORING SIGNIFICANT SHALLOWING OUT AND MODIFICATION OF THE
COLDER AIR. STILL THE LOWER MILK/LOWER MISSOURI RIVER VALLEYS WILL
LAG BEHIND IN THE WARMER TEMPS. SIMONSEN
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
THE EXTENDED PERIOD FEATURES A SERIES OF SHORTWAVE TROUGHS AND
RIDGES IN A PROGRESSIVE PATTERN. LIMITED MOISTURE WITH EACH OF THE
WEATHER SYSTEMS WILL LIMIT PRECIP CHANCES. TEMPERATURES WILL BE
WITHIN 10 DEGREES OF NORMAL DURING THE WHOLE PERIOD.
AN UPPER RIDGE MOVES TO THE EAST SATURDAY NIGHT AND SUNDAY WITH AN
UPPER TROUGH MOVING THROUGH EASTERN MONTANA ON MONDAY. THIS WILL
BRING A DRY COLD FRONT ACROSS THE AREA ON SUNDAY. LOOK FOR
SOMEWHAT COLDER AIR SUNDAY NIGHT AND MONDAY.
SHORTWAVE RIDGE FOLLOWS ON TUESDAY. ECMWF CURRENTLY WARMER THAN
THE GFS WITH THE TEMPERATURES. WILL FORECAST ON THE COLDER SIDE OF
THE POSSIBILITIES FOR NOW GIVEN THAT LIGHT WINDS SHOULD LEAD TO
POOR MIXING WITH LOW LEVEL INVERSIONS TRAPPING COLD AIR AT THE
SURFACE.
ANOTHER SHORTWAVE TROUGH MOVES THROUGH THE AREA WEDNESDAY AND THURSDAY
WITH ANOTHER DRY COLD FRONT AND SOMEWHAT COLDER AIR. FORRESTER
&&
.AVIATION...
CLOUDS ARE EXPECTED TO INCREASE OVER THE TAF SITES TODAY. FLURRIES
CAN BE EXPECTED IN THE AREA THIS AFTERNOON IF NOT LOW VFR
CLOUDINESS. VISIBILITIES COULD BRIEFLY DROP INTO MVFR CATEGORY.
ANOTHER BAND OF CLOUDINESS WILL MOVE ACROSS THE AREA FRIDAY...AND
BRIEF FLURRIES ARE AGAIN POSSIBLE. JAMBA
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION...CORRECTED HYDROLOGY
NWS NORTH PLATTE NE
348 PM CST THU DEC 8 2011
.DISCUSSION...
BANDED FOLDS OF THETA E AND EPV CONTINUE TO PRODUCE LIGHT TO
MODERATE SNOW. THE RUC SUGGESTS THIS SNOW SHOULD MOVE OUT OF THE FCST
AREA BY 02-03 UTC THIS EVENING. ANOTHER WEAK WAVE ACROSS ERN MT THIS
AFTN SHOULD SLICE THROUGH NCNTL NEB MAINLY AFTER 06Z TONIGHT THROUGH
15Z FRIDAY. THE NAM...GFS AND GEM SUPPORT THIS SOLN.
WE CONTINUE THE PATCHY FREEZING DRIZZLE ACROSS PARTS OF SCNTL AND
SWRN NEB THIS EVENING. AN ARCTIC FRONT CURRENTLY NEAR KTIF WILL MOVE
SOUTH AND WASHOUT PERHAPS DRYING THE MIDLEVEL ALLOWING FOR LOW LEVEL
SATURATION AND FREEZING DRIZZLE.
BEHIND THE SECOND DISTURBANCE TONIGHT ANOTHER ARCTIC HIGH WILL BUILD
INTO THE UPPER MISSOURI BASIN AND BE CENTERED OVER WRN SD/ND FRIDAY
MORNING. THIS IS A BIG BREAK FOR THE FCST AREA AS LOWS OF -20F
OCCURRED BENEATH ACROSS WRN CANADA THURSDAY MORNING. THIS HIGH IS
FCST TO DRIFT THROUGH THE FCST AREA FRIDAY PRODUCING CLEAR SKIES AND
COLD WEATHER WITH HIGHS ONLY IN THE 20S. BY FRIDAY EVENING...LOW
PRESSURE WILL BE TRACKING CNTL CANADA PRODUCING AS WARM WESTERLY
H850MB FLOW WITH H850 TEMPS RISING TO NEAR 0C BY SATURDAY MORNING.
THUS LOWS SHOULD OCCUR AT OR BEFORE MIDNIGHT MOST AREAS AND THEN
WARM.
FOR SATURDAY...WEST AND SOUTHWEST WINDS CONTINUE WITH HIGHS IN THE
40S. WINDS TAKE A MORE SOUTHERLY TACK SUNDAY AHEAD OF A COLD FRONT
PROGGED TO MOVE THROUGH SUNDAY NIGHT AND MONDAY. STILL HIGHS SUNDAY
SHOULD RISE INTO THE 40S. A COLD FRONT MOVING THROUGH MONDAY IS
EXPECTED TO TAKE THE EDGE OFF HIGHS. 30S APPEAR TO BE THE OPERATIVE
MODE.
THE GEM...GFS AND ECM ARE IN GOOD AGREEMENT ON A SIGNIFICANT SHORT
WAVE TRACKING THROUGH THE CNTL PLAINS WEDNESDAY. TEMPS MIGHT BE WARM
ENOUGH FOR RAIN AS H10-5 THICKNESSES HOVER NEAR 546DAM AND H850MB
TEMPS -3 TO 0C. A CHANCE OF RAIN AND SNOW IS SHOWN EAST WITH SLIGHT
CHANCE OF SNOW WEST. THE GFS AND GEM SHOW EVAPORATIVE COOLING WHILE
THE ECM DOES NOT. THIS SYSTEM SHOULD EXIT WEDNESDAY NIGHT WITH
ANOTHER STRONG COLD FRONT DROPPING TOWARD THE FCST AREA.
&&
.AVIATION...
OR 18Z TAFS...SMALLER SCALE FRONTOGENETIC BAND SLIDING ACROSS THE
SANDHILLS INTO LATE AFTERNOON LOWERING CREATING VSBYS TO 3/4 TO
1/2SM AT TIMES THOUGH LATE AFTERNOON. THIS AREA OF HEAVIER SNOWFALL
LIES BETWEEN THE KLBF AND KVTN TAF SITES...BUT MAY APPROACH THE KLBF
TAF SITE BY 22Z. LATEST NAM AND HRRR SUGGEST THIS WILL SLIDE NORTH
AND EAST OF KLBF HOWEVER AND AS SUCH HAVE NOT LOWERED VSBY AT KLBF
DUE TO THIS FEATURE. THIS TIGHTER...SMALLER SCALE BAND LIKELY A
RESULT OF LINGERING BUT WEAK FRONTOGENESIS IN A REGION OF NEGATIVE
EPV IN THE 700-600MB LAYER. WOULD EXPECT THIS BAND TO DISSIPATE IN
THE NEXT 2 TO 3 HRS AS WEAK INSTABILITY STABILIZES BUT WILL MONITOR.
LARGER SCALE DRIER AIR IS WORKING IN ACROSS THE WESTERN PORTION OF
THE STATE AND RADAR ECHOES ARE DECREASING SOME FROM WEST TO EAST AND
WILL EXPECT THAT TREND TO CONTINUE THROUGH EVENING.
FOR TONIGHT...SECONDARY SHORT WAVE SHOULD BE ENOUGH TO GENERATE
FLURRIES TO -SN ACROSS THE NORTHERN PORTION OF THE STATE...THOUGH
A MORE SHALLOW AREA OF LIFT CLOSER TO THE SURFACE AND FAVORABLE
CROSS-OVER TEMPS SHOULD LEAD TO AT LEAST BR BUT POSSIBLY FZFG
OVERNIGHT FURTHER SOUTH AND NEAR THE KLBF SITE. WILL BE REFINING
THIS PORTION OF THE FORECAST IN THE NEXT FEW HOURS SINCE
CONFIDENCE IN THIS SCENARIO IS LOW AT THE MOMENT. A GENERAL
CLEARING TREND IS EXPECTED BY LATE MORNING FRIDAY.
&&
.HYDROLOGY...
A FLOOD WARNING FOR ICE JAMMING HAS BEEN ISSUED ON THE NORTH
PLATTE RIVER AT LEWELLEN. THE FLOOD WARNING WILL CONTINUE UNTIL
FURTHER NOTICE. WEATHER CONDITIONS FEATURING WARM TEMPS DURING THE
DAYTIME AND SINGLE DIGITS AT NIGHT THIS WEEKEND COULD CAUSE THE
JAMMING TO PERSIST.
&&
$$
SHORT TERM/LONG TERM...CDC
AVIATION...JWS
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
312 PM CST THU DEC 8 2011
.DISCUSSION...
BANDED FOLDS OF THETA E AND EPV CONTINUE TO PRODUCE LIGHT TO
MODERATE SNOW. THE RUC SUGGESTS THIS SNOW SHOULD MOVE OUT OF THE FCST
AREA BY 02-03 UTC THIS EVENING. ANOTHER WEAK WAVE ACROSS ERN MT THIS
AFTN SHOULD SLICE THROUGH NCNTL NEB MAINLY AFTER 06Z TONIGHT THROUGH
15Z FRIDAY. THE NAM...GFS AND GEM SUPPORT THIS SOLN.
WE CONTINUE THE PATCHY FREEZING DRIZZLE ACROSS PARTS OF SCNTL AND
SWRN NEB THIS EVENING. AN ARCTIC FRONT CURRENTLY NEAR KTIF WILL MOVE
SOUTH AND WASHOUT PERHAPS DRYING THE MIDLEVEL ALLOWING FOR LOW LEVEL
SATURATION AND FREEZING DRIZZLE.
BEHIND THE SECOND DISTURBANCE TONIGHT ANOTHER ARCTIC HIGH WILL BUILD
INTO THE UPPER MISSOURI BASIN AND BE CENTERED OVER WRN SD/ND FRIDAY
MORNING. THIS IS A BIG BREAK FOR THE FCST AREA AS LOWS OF -20F
OCCURRED BENEATH ACROSS WRN CANADA THURSDAY MORNING. THIS HIGH IS
FCST TO DRIFT THROUGH THE FCST AREA FRIDAY PRODUCING CLEAR SKIES AND
COLD WEATHER WITH HIGHS ONLY IN THE 20S. BY FRIDAY EVENING...LOW
PRESSURE WILL BE TRACKING CNTL CANADA PRODUCING AS WARM WESTERLY
H850MB FLOW WITH H850 TEMPS RISING TO NEAR 0C BY SATURDAY MORNING.
THUS LOWS SHOULD OCCUR AT OR BEFORE MIDNIGHT MOST AREAS AND THEN
WARM.
FOR SATURDAY...WEST AND SOUTHWEST WINDS CONTINUE WITH HIGHS IN THE
40S. WINDS TAKE A MORE SOUTHERLY TACK SUNDAY AHEAD OF A COLD FRONT
PROGGED TO MOVE THROUGH SUNDAY NIGHT AND MONDAY. STILL HIGHS SUNDAY
SHOULD RISE INTO THE 40S. A COLD FRONT MOVING THROUGH MONDAY IS
EXPECTED TO TAKE THE EDGE OFF HIGHS. 30S APPEAR TO BE THE OPERATIVE
MODE.
THE GEM...GFS AND ECM ARE IN GOOD AGREEMENT ON A SIGNIFICANT SHORT
WAVE TRACKING THROUGH THE CNTL PLAINS WEDNESDAY. TEMPS MIGHT BE WARM
ENOUGH FOR RAIN AS H10-5 THICKNESSES HOVER NEAR 546DAM AND H850MB
TEMPS -3 TO 0C. A CHANCE OF RAIN AND SNOW IS SHOWN EAST WITH SLIGHT
CHANCE OF SNOW WEST. THE GFS AND GEM SHOW EVAPORATIVE COOLING WHILE
THE ECM DOES NOT. THIS SYSTEM SHOULD EXIT WEDNESDAY NIGHT WITH
ANOTHER STRONG COLD FRONT DROPPING TOWARD THE FCST AREA.
&&
.AVIATION...
OR 18Z TAFS...SMALLER SCALE FRONTOGENETIC BAND SLIDING ACROSS THE
SANDHILLS INTO LATE AFTERNOON LOWERING CREATING VSBYS TO 3/4 TO
1/2SM AT TIMES THOUGH LATE AFTERNOON. THIS AREA OF HEAVIER SNOWFALL
LIES BETWEEN THE KLBF AND KVTN TAF SITES...BUT MAY APPROACH THE KLBF
TAF SITE BY 22Z. LATEST NAM AND HRRR SUGGEST THIS WILL SLIDE NORTH
AND EAST OF KLBF HOWEVER AND AS SUCH HAVE NOT LOWERED VSBY AT KLBF
DUE TO THIS FEATURE. THIS TIGHTER...SMALLER SCALE BAND LIKELY A
RESULT OF LINGERING BUT WEAK FRONTOGENESIS IN A REGION OF NEGATIVE
EPV IN THE 700-600MB LAYER. WOULD EXPECT THIS BAND TO DISSIPATE IN
THE NEXT 2 TO 3 HRS AS WEAK INSTABILITY STABILIZES BUT WILL MONITOR.
LARGER SCALE DRIER AIR IS WORKING IN ACROSS THE WESTERN PORTION OF
THE STATE AND RADAR ECHOES ARE DECREASING SOME FROM WEST TO EAST AND
WILL EXPECT THAT TREND TO CONTINUE THROUGH EVENING.
FOR TONIGHT...SECONDARY SHORT WAVE SHOULD BE ENOUGH TO GENERATE
FLURRIES TO -SN ACROSS THE NORTHERN PORTION OF THE STATE...THOUGH
A MORE SHALLOW AREA OF LIFT CLOSER TO THE SURFACE AND FAVORABLE
CROSS-OVER TEMPS SHOULD LEAD TO AT LEAST BR BUT POSSIBLY FZFG
OVERNIGHT FURTHER SOUTH AND NEAR THE KLBF SITE. WILL BE REFINING
THIS PORTION OF THE FORECAST IN THE NEXT FEW HOURS SINCE
CONFIDENCE IN THIS SCENARIO IS LOW AT THE MOMENT. A GENERAL
CLEARING TREND IS EXPECTED BY LATE MORNING FRIDAY.
&&
.HYDROLOGY...
ICE JAMMING HAS DEVELOPED ON THE NORTH PLATTE RIVER BETWEEN LEWELLEN
AND NORTH PLATTE. A FLOOD ADVISORY WILL CONTINUE UNTIL FURTHER
NOTICE. WEATHER CONDITIONS FEATURING WARM TEMPS DURING THE DAYTIME
AND SINGLE DIGITS AT NIGHT THIS WEEKEND COULD CAUSE THE JAMMING TO
PERSIST.
&&
$$
SHORT TERM/LONG TERM...CDC
AVIATION...JWS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
244 PM CST THU DEC 8 2011
.DISCUSSION...
BANDED FOLDS OF THETA E AND EPV CONTINUE TO PRODUCE LIGHT TO
MODERATE SNOW. THE RUC SUGGESTS THIS SNOW SHOULD MOVE OUT OF THE FCST
AREA BY 02-03 UTC THIS EVENING. ANOTHER WEAK WAVE ACROSS ERN MT THIS
AFTN SHOULD SLICE THROUGH NCNTL NEB MAINLY AFTER 06Z TONIGHT THROUGH
15Z FRIDAY. THE NAM...GFS AND GEM SUPPORT THIS SOLN.
WE CONTINUE THE PATCHY FREEZING DRIZZLE ACROSS PARTS OF SCNTL AND
SWRN NEB THIS EVENING. AN ARCTIC FRONT CURRENTLY NEAR KTIF WILL MOVE
SOUTH AND WASHOUT PERHAPS DRYING THE MIDLEVEL ALLOWING FOR LOW LEVEL
SATURATION AND FREEZING DRIZZLE.
BEHIND THE SECOND DISTURBANCE TONIGHT ANOTHER ARCTIC HIGH WILL BUILD
INTO THE UPPER MISSOURI BASIN AND BE CENTERED OVER WRN SD/ND FRIDAY
MORNING. THIS IS A BIG BREAK FOR THE FCST AREA AS LOWS OF -20F
OCCURRED BENEATH ACROSS WRN CANADA THURSDAY MORNING. THIS HIGH IS
FCST TO DRIFT THROUGH THE FCST AREA FRIDAY PRODUCING CLEAR SKIES AND
COLD WEATHER WITH HIGHS ONLY IN THE 20S. BY FRIDAY EVENING...LOW
PRESSURE WILL BE TRACKING CNTL CANADA PRODUCING AS WARM WESTERLY
H850MB FLOW WITH H850 TEMPS RISING TO NEAR 0C BY SATURDAY MORNING.
THUS LOWS SHOULD OCCUR AT OR BEFORE MIDNIGHT MOST AREAS AND THEN
WARM.
FOR SATURDAY...WEST AND SOUTHWEST WINDS CONTINUE WITH HIGHS IN THE
40S. WINDS TAKE A MORE SOUTHERLY TACK SUNDAY AHEAD OF A COLD FRONT
PROGGED TO MOVE THROUGH SUNDAY NIGHT AND MONDAY. STILL HIGHS SUNDAY
SHOULD RISE INTO THE 40S. A COLD FRONT MOVING THROUGH MONDAY IS
EXPECTED TO TAKE THE EDGE OFF HIGHS. 30S APPEAR TO BE THE OPERATIVE
MODE.
THE GEM...GFS AND ECM ARE IN GOOD AGREEMENT ON A SIGNIFICANT SHORT
WAVE TRACKING THROUGH THE CNTL PLAINS WEDNESDAY. TEMPS MIGHT BE WARM
ENOUGH FOR RAIN AS H10-5 THICKNESSES HOVER NEAR 546DAM AND H850MB
TEMPS -3 TO 0C. A CHANCE OF RAIN AND SNOW IS SHOWN EAST WITH SLIGHT
CHANCE OF SNOW WEST. THE GFS AND GEM SHOW EVAPORATIVE COOLING WHILE
THE ECM DOES NOT. THIS SYSTEM SHOULD EXIT WEDNESDAY NIGHT WITH
ANOTHER STRONG COLD FRONT DROPPING TOWARD THE FCST AREA.
&&
.AVIATION...
OR 18Z TAFS...SMALLER SCALE FRONTOGENETIC BAND SLIDING ACROSS THE
SANDHILLS INTO LATE AFTERNOON LOWERING CREATING VSBYS TO 3/4 TO
1/2SM AT TIMES THOUGH LATE AFTERNOON. THIS AREA OF HEAVIER SNOWFALL
LIES BETWEEN THE KLBF AND KVTN TAF SITES...BUT MAY APPROACH THE KLBF
TAF SITE BY 22Z. LATEST NAM AND HRRR SUGGEST THIS WILL SLIDE NORTH
AND EAST OF KLBF HOWEVER AND AS SUCH HAVE NOT LOWERED VSBY AT KLBF
DUE TO THIS FEATURE. THIS TIGHTER...SMALLER SCALE BAND LIKELY A
RESULT OF LINGERING BUT WEAK FRONTOGENESIS IN A REGION OF NEGATIVE
EPV IN THE 700-600MB LAYER. WOULD EXPECT THIS BAND TO DISSIPATE IN
THE NEXT 2 TO 3 HRS AS WEAK INSTABILITY STABILIZES BUT WILL MONITOR.
LARGER SCALE DRIER AIR IS WORKING IN ACROSS THE WESTERN PORTION OF
THE STATE AND RADAR ECHOES ARE DECREASING SOME FROM WEST TO EAST AND
WILL EXPECT THAT TREND TO CONTINUE THROUGH EVENING.
FOR TONIGHT...SECONDARY SHORT WAVE SHOULD BE ENOUGH TO GENERATE
FLURRIES TO -SN ACROSS THE NORTHERN PORTION OF THE STATE...THOUGH
A MORE SHALLOW AREA OF LIFT CLOSER TO THE SURFACE AND FAVORABLE
CROSS-OVER TEMPS SHOULD LEAD TO AT LEAST BR BUT POSSIBLY FZFG
OVERNIGHT FURTHER SOUTH AND NEAR THE KLBF SITE. WILL BE REFINING
THIS PORTION OF THE FORECAST IN THE NEXT FEW HOURS SINCE
CONFIDENCE IN THIS SCENARIO IS LOW AT THE MOMENT. A GENERAL
CLEARING TREND IS EXPECTED BY LATE MORNING FRIDAY.
&&
$$
SHORT TERM/LONG TERM...CDC
AVIATION...JWS
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
149 PM CST THU DEC 8 2011
.UPDATE...
UPDATED FOR WARMER TEMPERATURES AGAIN THIS AFTERNOON...CLOSE TO
LATEST RUC SOLUTION WHICH SEEMS TO BE STRUGGLING LESS WITH THE
THINNING SNOW COVERAGE THAN EITHER THE WRF/NAM OR GFS. FRONT STILL
EXPECTED TO DROP SOUTHWARD THIS EVENING. RMCQUEEN
&&
.AVIATION...
PRE-FRONTAL VFR CONDITIONS WITH DOWNSLOPE BREEZES. COLD FRONT WILL
EDGE SOUTHWARD THIS EVENING...CLOSE TO PREVIOUS TIMING. WE ARE
LEANING MORE TOWARDS AREAS OF SURFACE SATURATION DEVELOPING LATER
TONIGHT...POSSIBLE FOG...WHILE THE GFS STILL FAVORS LIFTING THIS
INTO A LOW STRATUS DECK NEAR OR SHORTLY AFTER SUNRISE FRIDAY. WE
WILL RETAIN TEMPO GROUPS FOR NEAR-IFR STRATUS LAYER STARTING
BEFORE DAYBREAK FRIDAY. RMCQUEEN
&&
.PREV DISCUSSION... /ISSUED 555 AM CST THU DEC 8 2011/
AVIATION...
VFR CONDITIONS WILL PERSIST AT BOTH KLBB AND KCDS THROUGH AT LEAST
09/00Z. CONFIDENCE THEN DECREASES AS MODELS SHOW A MOISTENING LOW
LEVEL ATMOSPHERE IN THE WAKE OF A COLD FRONT. CURRENT INDICATIONS
SUGGEST THAT IFR CIG RESTRICTIONS COULD OCCUR DURING THE 06-12Z
TIME-FRAME. FOG MAY BE AN OUTSIDE POSSIBILITY...BUT CONFIDENCE IN
THIS IS LOW GIVEN CONTINUED NORTH/NORTHWESTERLY WINDS WHICH MAY
HELP LIMIT SURFACE FOG POTENTIAL.
PREV DISCUSSION... /ISSUED 406 AM CST THU DEC 8 2011/
SHORT TERM...
TODAY/S FORECAST IS COMPLICATED BY AN ANTICIPATED FRONTAL PASSAGE.
THE CURRENTLY DIFFUSE FRONTAL BOUNDARY OVER THE CENTRAL PLAINS WILL
MAKE AN ACCELERATED PUSH SOUTHWARD TODAY IN THE WAKE OF A SHARPENING
SHORTWAVE TROUGH OVER THE NORTHERN PLAINS/UPPER MIDWEST. MODELS SHOW
THIS FRONT ENTERING THE EXTREME SOUTHWESTERN PANHANDLE BY LATE
AFTERNOON...THEN CLEARING THE FORECAST AREA BY 06-09Z.
TIMING OF THE FRONT AND PROSPECTS FOR AT LEAST SOME MID/HIGH CLOUDS
ASSOCIATED WITH A SUBTLE SHORTWAVE TROUGH SEEN IN VAPOR IMAGERY OVER
NEW MEXICO WILL MAKE FOR PROBLEMATIC AFTERNOON TEMPERATURE
FORECASTS. AS WAS THE CASE YESTERDAY...MOS VALUES APPEAR LOW GIVEN
PROGGED LOW LEVEL THERMAL PROFILES AND THICKNESSES. THUS HAVE EDGED
FORECAST TEMPERATURE MAXIMA UP 5+ DEGREES RELATIVE TO GUIDANCE.
FORECAST PROFILES SHOW CONSIDERABLE POST FRONTAL MOISTENING OF THE
LOWER TROPOSPHERE BY LATE EVENING/OVERNIGHT. GIVEN PERSISTENT
NORTH/NORTHWESTERLY DOWNSLOPE WINDS NEAR 10 KT WILL FAVOR AN
INCREASING STRATUS DECK VERSUS FOG ATTM.
LONG TERM...
NEAR ZONAL FLOW ALOFT WILL ENSUE LATE THURSDAY THROUGH FRIDAY...AS
AN UA DISTURBANCE ACROSS THE CENTRAL/HIGH PLAINS DIVES A COLD FRONT
ACROSS THE SOUTHERN PLAINS TODAY. ALTHOUGH UPPER LEVEL ATMOSPHERIC
LEVELS APPEAR RATHER DRY /PWATS BELOW 0.40 INCHES/...POST FRONTAL
LOW LEVEL MOISTENING IS EXHIBITED FRIDAY MORNING...WITH HINTS OF
POTENTIAL FOG. HOWEVER..NORTHERLY WIND SPEEDS AOA 10 KTS MAY AID
TO MITIGATE THE PRODUCTION OF FOG AND WILL NOT ADD A MENTION WITH
THIS FORECAST PACKAGE ATTM. THUS CURRENT THINKING IS THAT COOL
TEMPS /30S AND 40S / AND INCREASING LOW LEVEL CLOUDINESS WILL BE
THE RULE. SFC RIDGE WILL TRANSLATE NE OF THE REGION ON
SATURDAY...AND PROMOTE SFC WINDS TO VEER TO A MORE SOUTH TO
SOUTHEASTERLY/UPSLOPE WIND COMPONENT...WHICH MAY ENSUE THROUGH
MONDAY MORNING. TEMPS WILL WARM INTO THE 40S AND 50S ON SUNDAY AND
MONDAY AS SHORTWAVE RIDGING PASSES OVERHEAD...AND SLIGHTLY BREEZY
SOUTHERLY SFC WINDS OCCURS DURING THE AFTERNOON HOURS.
FURTHERMORE....BOTH THE GFS AND ECMWF HINT AT THE NORTHWARD
TRANSPORT OF LOW LEVEL MOISTURE AND LIGHT QPF VALUES ESPECIALLY
ACROSS ERN ZONES THROUGH THE AFOREMENTIONED PERIOD.
CONCURRENTLY...THE EVOLUTION OF FLOW ALOFT FROM NEAR ZONAL TO SW
FLOW WILL TAKE PLACE...AS A PACIFIC UA LOW COMMENCE TO MOVE ESE
ACROSS CALIFORNIA. THEREAFTER...MODELS STILL STRUGGLE WITH HOW
THIS UA DISTURBANCE WILL EVOLVE.
IF FOLLOWING THE GFS /WHICH HAS SHOWN INCONSISTENCY FROM RUN TO RUN
THE LAST FEW DAYS/ QUICKLY PROPAGATES THE PACIFIC UA DISTURBANCE
ACROSS THE DESERT SW ON TUESDAY AND ACROSS THE CWA ON WEDNESDAY. A
BREEZY NORTHWESTERLY PACIFIC FRONT WILL MOVE ACROSS THE REGION
WEDNESDAY WITH A DECLINE IN PRECIP FROM WEST TO EAST. THE SYSTEM
WILL BE EAST OF THE CWA BY THURSDAY. PRECIP TYPE APPEARS TO BE ALL
LIQUID AS 850 MB TEMPS REMAIN ABOVE 0 DEGREES CELSIUS. HOWEVER THE
GFS COULD BE OVER DOING THE WARMTH ALOFT AND WITHIN THE BL. THE ECMWF
SOLUTION ON THE OTHER-HAND IS A BIT STRONGER WITH THE UA LOW AS IT
SLOWLY TRANSLATES IT TO ACROSS THE DESERT SW WEDNESDAY
MORNING...BEFORE EJECTING NE TO ACROSS THE CENTRAL PLAINS WEDNESDAY
NIGHT. BREEZY WESTERLY WINDS WILL ENSUE AS THE SYSTEM BRUSHES THE
CWA. AN ALL LIQUID PRECIP TYPE IS ALSO SHOWN BY THE ECMWF. WILL TEND
TO LEAN TOWARDS THE ECMWF AS IT HAS BEEN MOST CONSISTENT.
HOWEVER...HAVE DECIDED TO MAINTAIN SILENT POPS /ALTHOUGH BUMPED POPS
TO 10 PERCENT TUESDAY NIGHT-WEDNESDAY/ ATTM AS THE ANALYSIS OF
FUTURE MODEL RUNS FOR CONSISTENCY IS HIGHLY DESIRED.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 15 33 20 40 22 / 0 10 0 0 0
TULIA 20 36 22 42 23 / 10 10 0 0 0
PLAINVIEW 21 37 23 43 25 / 0 10 0 0 0
LEVELLAND 19 38 24 43 25 / 0 10 0 0 0
LUBBOCK 21 39 24 44 26 / 0 10 0 0 10
DENVER CITY 21 39 24 43 27 / 0 10 0 0 10
BROWNFIELD 21 39 25 44 27 / 0 10 0 0 10
CHILDRESS 25 38 27 47 28 / 10 10 0 0 0
SPUR 24 38 25 46 27 / 0 10 0 0 10
ASPERMONT 26 41 28 48 30 / 0 10 0 0 10
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/99/05