Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/05/12
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1009 AM MST MON DEC 3 2012
.UPDATE...
ISSUED AT 1009 AM MST MON DEC 3 2012
THE FRONT THAT MOVED THROUGH LAST NIGHT HAS WASHED OUT WITH PRECIP
ENDING OR CLOSE TO ENDING FOR MOST AREAS THIS MORNING. CDOT
WEBCAMS AND AREA WEBCAMS SHOW PLENTY OF SUN OVER THE PARK/GORE
RANGES AND ALSO THE ELKHEADS THOUGH SOME SNOW REMAINS NEAR VAIL
PASS. DROPPED POPS FOR THIS UPDATE TO REMOVE POPS FOR THOSE AREAS
WHILE KEEPING ISOLD SHOWERS ALONG THE CONTINENTAL DIVIDE.
POT VORT FIELDS CLEARLY SHOW A WEAK SHORTWAVE MOVING OVER THE
REGION THIS EVENING AND VIS SATELLITE IMAGERY IS PICKING UP ON
THIS WITH AN AREA OF CLOUDS CURRENTLY MOVING OVER EASTERN UTAH AND
HEADING OUR WAY. WHILE MODELS SHOW NO PRECIP FOR SAN JUANS...LIKE
THE IDEA THAT OROGRAPHICS AND FAVORABLE WIND FLOW WILL CAUSE SOME
VERY ISOLATED SNOW TO FALL MAINLY OVER THE HIGHEST TERRAIN.
ALSO INCREASED SKY COVER AS SHORTWAVE MOVES OVER REGION WITH
SCATTERED TO BROKEN SKIES EXPECTED THOUGH THEY SHOULD BE FAIRLY
HIGH.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 342 AM MST MON DEC 3 2012
VIGOROUS COLD FRONT HAS BEEN PUSHING THROUGH THE NORTHERN AND
CENTRAL ZONES SINCE MIDNIGHT. AT 3 AM IT WAS INTO THE I-70
CORRIDOR AND PUSHING TO THE SE AT 25 MPH. SNOW LEVELS WERE QUICKLY
LOWERING TO AROUND 7KFT BEHIND THE FRONT. MOSBY MTN SNOTEL IN THE
EASTERN UINTA MTNS PICKED UP A QUICK 4 INCHES WITH THE FRONT THIS
EARLY MORNING. VALLEY GROUND TEMPERATURES THOUGH WERE VERY WARM SO
SNOW WAS STICKING MAINLY TO VEGETATION. THE 08Z RAP MODEL SHOWS THE
FRONT SHEARING AND WASHING OUT AS IT MOVES SOUTH OF I-70. SO THE
SOUTHERN VALLEYS WILL GET ONLY PIECEMEAL COOL ADVECTION THIS
MORNING. THE FAVORED MTNS INCLUDE THE PARK...FLATTOPS...THE
EASTERN PORTION OF THE GRAND MESA AND WESTERN PORTION OF THE ELKS.
THESE AREAS ARE STILL PROGGED TO GET 2-6 INCHES WITH LOCALIZED
HIGHER AMOUNTS IN CONVECTIVE SHOWERS.
SO THE FRONTAL PRECIPITATION WILL TAPER OFF QUICKLY THIS MORNING
LEAVING ONLY SCATTERED CONVECTIVE AFTERNOON SHOWERS IN ITS WAKE. A
DISTURBANCE PASSES THROUGH THE SOUTHERN CWA THIS AFTERNOON. SO
ENHANCED THE AFTERNOON POPS FOR THE SOUTHERN MTNS UNTIL SUNSET.
MAX TEMPERATURES FOR THE DAY MAY HAVE ALREADY BEEN REACHED FOR
SITES NORTH OF AND ALONG I-70.
A DRIER AIR MASS TONIGHT ALLOWS FOR MIN TEMPERATURES TO DROP TO
CLOSE TO NORMAL...EVEN BELOW NORMAL ACROSS THE NORTH.
TUESDAY...A BROAD RIDGE AXIS BUILDS IN FROM THE WEST. FLOW ALOFT
BACKS TO SW AND BOTH THE MTN AND VALLEY TEMPERATURES AGAIN CLIMB
TO WELL ABOVE NORMAL.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 342 AM MST MON DEC 3 2012
SHRTWV RIDGING TUESDAY WILL FLATTEN WITH NEAR ZONAL FLOW SETTING
UP WEDNESDAY THROUGH SATURDAY. DEEP PACIFIC MOISTURE AND EMBEDDED
WAVES OF ENERGY WILL BRING AN INCREASING CHANCE OF PRECIPITATION
TO THE REGION...ESPECIALLY WEDNESDAY NIGHT AND THURSDAY AS A
SLIGHTLY STRONGER PIECE OF ENERGY WORKS THROUGH. PLENTY OF
OROGRAPHICS WILL ALSO BE COMING INTO THE PLAY WITH THE WESTERLY
COMPONENT FAVORING MOUNTAINS ALONG THE DIVIDE AND MAINLY NORTH OF
INTERSTATE 70.
BY LATE IN THE WEEKEND...HEIGHTS CLIMB ACROSS THE EASTERN PACIFIC
WITH STRONG SURGE OF ENERGY DROPPING SOUTH OUT OF THE GULF OF
ALASKA. MEDIUM RANGE MODELS CONTINUE TO HINT AT A MAJOR COOL DOWN
FOR OUR AREA SUNDAY AND MONDAY WITH WIDESPREAD PRECIPITATION
BREAKING OUT AS ENERGY PINCHES OFF IN THE BASE OF THE DIGGING
TROUGH WITH A CLOSED LOW EVENTUALLY REACHING THE FOUR CORNERS.
THERE REMAINS SOME TIMING ISSUES AND GFS HAS STARTED TO SLOW THE
EVOLUTION DOWN A BIT...KEEPING CONFIDENCE AT A MINIMUM AT THIS
TIME.
WILL INCREASE POPS FROM INHERITED GRIDS AND LOWER TEMPS A BIT LATE
IN THE WEEKEND TO AT LEAST ADVERTISE THIS POSSIBLE CHANGE TO MORE
WINTER LIKE WEATHER.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z NOON TUESDAY)
ISSUED AT 1009 AM MST MON DEC 3 2012
SOME MVFR REMAINS FOR VARIOUS AIRPORTS ACROSS THE REGION BUT
EXPECT A RETURN TO VFR OVER THE NEXT FEW HOURS. A WEAK DISTURBANCE
WILL MOVE OVERHEAD THIS EVENING BRINGING MORE MID-LEVEL CLOUDS
WITH POSSIBLY SOME LGT PRECIP AND MOUNTAIN OBSCURATIONS FOR THE
SAN JUANS. ALL TAF SITES WILL REMAIN VFR.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...TGR
SHORT TERM...JOE
LONG TERM...JDC
AVIATION...TGR
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
343 AM MST MON DEC 3 2012
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 342 AM MST MON DEC 3 2012
VIGOROUS COLD FRONT HAS BEEN PUSHING THROUGH THE NORTHERN AND
CENTRAL ZONES SINCE MIDNIGHT. AT 3 AM IT WAS INTO THE I-70
CORRIDOR AND PUSHING TO THE SE AT 25 MPH. SNOW LEVELS WERE QUICKLY
LOWERING TO AROUND 7KFT BEHIND THE FRONT. MOSBY MTN SNOTEL IN THE
EASTERN UINTA MTNS PICKED UP A QUICK 4 INCHES WITH THE FRONT THIS
EARLY MORNING. VALLEY GROUND TEMPERATURES THOUGH WERE VERY WARM SO
SNOW WAS STICKING MAINLY TO VEGETATION. THE 08Z RAP MODEL SHOWS THE
FRONT SHEARING AND WASHING OUT AS IT MOVES SOUTH OF I-70. SO THE
SOUTHERN VALLEYS WILL GET ONLY PIECEMEAL COOL ADVECTION THIS
MORNING. THE FAVORED MTNS INCLUDE THE PARK...FLATTOPS...THE
EASTERN PORTION OF THE GRAND MESA AND WESTERN PORTION OF THE ELKS.
THESE AREAS ARE STILL PROGGED TO GET 2-6 INCHES WITH LOCALIZED
HIGHER AMOUNTS IN CONVECTIVE SHOWERS.
SO THE FRONTAL PRECIPITATION WILL TAPER OFF QUICKLY THIS MORNING
LEAVING ONLY SCATTERED CONVECTIVE AFTERNOON SHOWERS IN ITS WAKE. A
DISTURBANCE PASSES THROUGH THE SOUTHERN CWA THIS AFTERNOON. SO
ENHANCED THE AFTERNOON POPS FOR THE SOUTHERN MTNS UNTIL SUNSET.
MAX TEMPERATURES FOR THE DAY MAY HAVE ALREADY BEEN REACHED FOR
SITES NORTH OF AND ALONG I-70.
A DRIER AIR MASS TONIGHT ALLOWS FOR MIN TEMPERATURES TO DROP TO
CLOSE TO NORMAL...EVEN BELOW NORMAL ACROSS THE NORTH.
TUESDAY...A BROAD RIDGE AXIS BUILDS IN FROM THE WEST. FLOW ALOFT
BACKS TO SW AND BOTH THE MTN AND VALLEY TEMPERATURES AGAIN CLIMB
TO WELL ABOVE NORMAL.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 342 AM MST MON DEC 3 2012
SHRTWV RIDGING TUESDAY WILL FLATTEN WITH NEAR ZONAL FLOW SETTING
UP WEDNESDAY THROUGH SATURDAY. DEEP PACIFIC MOISTURE AND EMBEDDED
WAVES OF ENERGY WILL BRING AN INCREASING CHANCE OF PRECIPITATION
TO THE REGION...ESPECIALLY WEDNESDAY NIGHT AND THURSDAY AS A
SLIGHTLY STRONGER PIECE OF ENERGY WORKS THROUGH. PLENTY OF
OROGRAPHICS WILL ALSO BE COMING INTO THE PLAY WITH THE WESTERLY
COMPONENT FAVORING MOUNTAINS ALONG THE DIVIDE AND MAINLY NORTH OF
INTERSTATE 70.
BY LATE IN THE WEEKEND...HEIGHTS CLIMB ACROSS THE EASTERN PACIFIC
WITH STRONG SURGE OF ENERGY DROPPING SOUTH OUT OF THE GULF OF
ALASKA. MEDIUM RANGE MODELS CONTINUE TO HINT AT A MAJOR COOL DOWN
FOR OUR AREA SUNDAY AND MONDAY WITH WIDESPREAD PRECIPITATION
BREAKING OUT AS ENERGY PINCHES OFF IN THE BASE OF THE DIGGING
TROUGH WITH A CLOSED LOW EVENTUALLY REACHING THE FOUR CORNERS.
THERE REMAINS SOME TIMING ISSUES AND GFS HAS STARTED TO SLOW THE
EVOLUTION DOWN A BIT...KEEPING CONFIDENCE AT A MINIMUM AT THIS
TIME.
WILL INCREASE POPS FROM INHERITED GRIDS AND LOWER TEMPS A BIT LATE
IN THE WEEKEND TO AT LEAST ADVERTISE THIS POSSIBLE CHANGE TO MORE
WINTER LIKE WEATHER.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 342 AM MST MON DEC 3 2012
THROUGH 15Z THIS MORNING...CIGS WILL BE BKN020-040 ACROSS THE
NORTH INCLUDING KVEL KHDN KSBS KASE KEGE WITH WIDESPREAD
-SHSN/-SHRA WITH SNOW LEVEL LOWERING TO 070. AREAS OF IFR FROM
PASSING SHOWERS ARE EXPECTED AS WELL AS MOUNTAIN OBSCURATIONS.
AFTER 15Z...EXPECT LIFTING CIGS THEN DISSIPATING AFTER 18Z. VFR
AT ALL TAF SITES AFTER 18Z THOUGH SCT SHSN WILL LINGER OVER HIGHER
TERRAIN THROUGH 00Z OBSCURING MTNS TOPS AT TIMES.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...JOE
LONG TERM...JDC
AVIATION...JOE
AREA FORECAST DISCUSSION...UPDATED
NWS TAMPA BAY RUSKIN FL
455 AM EST MON DEC 3 2012
.UPDATE...
BASED ON LATEST EARLY MORNING SATELLITE TRENDS AND LOCAL HI-RES NWP
GUIDANCE...HAVE INCREASED THE SKY COVER QUITE A BIT FOR THE FIRST
PORTION OF THE MORNING OVER MUCH OF THE REGION. ALTHOUGH LITTLE
MOVEMENT IS CURRENTLY SEEN IN THIS CLOUD DECK...THERE ARE MODEL
INDICATIONS THAT WE WILL BEGIN TO SEE THE AREA PIVOT WEST AND
NORTHWEST WITH TIME...AND ALSO BEGIN TO SCT OUT LATER THIS MORNING.
HAVE TRIED TO INCORPORATE THIS TREND INTO THE SKY GRIDS OVER THE
NEXT 4-6 HOURS BRINGING A MIX OF SUN AND CLOUDS BACK TO THE FORECAST
BY MIDDAY.
&&
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOW A GENERALLY UNAMPLIFIED
UPPER LEVEL PATTERN ACROSS THE CONUS. NORTHERN STREAM FLOW IS
COMPRISED OF SHORTWAVE ENERGY EJECTING EASTWARD FROM THE
INTER-MOUNTAIN WEST FOLLOWED DOWNSTREAM BY LONGWAVE RIDGING OVER THE
MIDWEST...AND THEN FINALLY ANOTHER SHORTWAVE TROUGH EXITING THE NEW
ENGLAND STATES TOWARD THE CANADIAN MARITIMES. CLOSER TO HOME...OUR
FORECAST AREA RESIDES UNDER WEAK UPPER RIDGING COVERING THE GULF OF
MEXICO/SE CONUS. THE INFLUENCE OF THIS RIDGING CAN BE SEEN ON THE
03/00Z KTBW SOUNDING PROFILE...WHICH SHOWED A WELL-DEFINED
SUBSIDENCE INVERSION AT AROUND 800MB. A RATHER DRY MID/UPPER LEVEL
COLUMN ABOVE THIS FEATURE RESULTED IN A PW VALUE OF UNDER 1".
AT THE SURFACE...HIGH PRESSURE IS IN CONTROL OF THE REGION WITH A
SURFACE RIDGE AXIS EXTENDING FROM OFF THE SE CONUS COAST BACK
WESTWARD THROUGH SOUTHERN GA/AL. GRADIENT AROUND THIS RIDGE
CONTINUES TO PROVIDE THE REGION WITH AN EASTERLY LOW LEVEL FLOW.
THIS FLOW IS BRINGING WITH IT AMPLE BOUNDARY LAYER MOISTURE THIS
MORNING. SCT-BK CLOUDS RESULTING FROM THIS MOISTURE ARE OCCASIONALLY
WORKING THEIR WAY WESTWARD ACROSS THE PENINSULA. AREAS OF FOG HAVE
BEGUN TO DEVELOP TO THE NORTH OF TAMPA BAY AND WILL HIGHLIGHT SOME
DENSE FOG POTENTIAL IN THE GRIDS FOR THE NATURE COAST ZONES...
ESPECIALLY NORTH OF BROOKSVILLE.
&&
.SHORT TERM (TODAY THROUGH WEDNESDAY)...
TODAY/TONIGHT/TUESDAY...STACKED RIDGING AND LARGE SCALE SUPPRESSION
WILL BE THE DOMINANT PLAYER IN OUR WEATHER THROUGH TUESDAY. UPPER
LEVEL RIDGE WILL EVEN SHARPEN SOMEWHAT DURING THE NEXT 24 HOURS IN
RESPONSE TO HEIGHT FALLS SPREADING EASTWARD OVER THE SOUTHERN
PLAINS. THE FORECAST UNDER THIS PATTERN WILL BE GENERALLY DRY WITH
ABOVE NORMAL TEMPERATURES. TYPICAL OF THIS TYPE OF EASTERLY FLOW
PATTERN...WILL CONTINUE TO SEE SHALLOW SPEED CONVERGENCE FOCUS
SHOWERS FORMING FROM TIME TO TIME ALONG THE EAST COAST OF FLORIDA...
AND THEN HEADING INLAND. THE MAJORITY OF THIS LIGHT SHOWER/SPRINKLE
ACTIVITY WILL DISSIPATE BEFORE REACHING OUR ZONES...HOWEVER A FEW
ISOLATED CELLS CAN NOT BE RULED OUT THIS FAR WEST. THE CHANCE OF ANY
MEASURABLE RAINFALL IS VERY LOW DUE TO THE EXTREMELY SHALLOW NATURE
OF THE AVAILABLE MOISTURE. SIMILAR DIURNAL MIXING HEIGHTS TO WHAT
OCCURRED SUNDAY ARE ANTICIPATED THE NEXT COUPLE OF DAYS. MIXING TO
BETWEEN 875-850MB TODAY AND TUESDAY WILL YIELD HIGH TEMPERATURES
INTO THE UPPER 70S/LOW 80 FOR MANY LOCATIONS. LOW TEMP RANGE BY
SUNRISE FROM THE LOWER 50S AT NORMALLY COLDER INLAND SPOTS TO LOWER
60S AT NORMALLY WARMER COASTAL LOCATIONS.
TUESDAY NIGHT/WEDNESDAY...UPPER RIDGE OVER THE FL PENINSULA RAPIDLY
BREAKS DOWN TUESDAY NIGHT/EARLY WEDNESDAY AS SHORTWAVE ENERGY
APPROACHES AND OVERSPREAD THE REGION FROM THE NORTHWEST. GLOBAL
GUIDANCE CONTINUES TO EVOLVE THE DETAILS OF THIS ENERGY SLIGHTLY
DIFFERENT...WITH THE GFS FURTHER NORTH AND MORE PROGRESSIVE THAN THE
ECMWF. SURFACE COLD FRONT ASSOCIATED WITH THIS ENERGY WILL ALSO BE
APPROACHING FROM THE NORTHWEST. SIMILAR TO THE PAST SEVERAL
FRONTS...THIS BOUNDARY LOOKS TO "LOSE STEAM" AND BEGIN TO WASH OUT
AS IT REACHES THE I-10 CORRIDOR LATE WEDNESDAY. DESPITE AT LEAST
SOME DEEP LAYER QG FORCING/SYNOPTIC SUPPORT AHEAD OF THE SHORTWAVE
DURING THE DAY ON WEDNESDAY...THE LACK OF COINCIDENT COLUMN MOISTURE
AND FADING FRONTAL FOCUS IN THE LOWER LEVELS WILL LIKELY KEEP RAIN
CHANCES LOW. A FEW ISOLATED SHOWERS/SPRINKLES SHOULD BE IN THE AREA
WEDNESDAY...HOWEVER...IMPACTS WILL BE VERY MINOR/NIL WITH REGARDS TO
OUTDOOR ACTIVITIES...AND WILL KEEP POPS AT AROUND 10%. LOWERED
HEIGHTS AND THE POTENTIAL FOR MORE CLOUDS AHEAD OF THE SHORTWAVE
WOULD KEEP DAYTIME TEMPS DOWN A FEW DEGREES FROM PREVIOUS DAYS...BUT
SHOULD NOT SEE ANY SIGNIFICANT DEPARTURES ON EITHER SIDE OF NORMAL.
&&
.LONG TERM (THURSDAY THROUGH NEXT SUNDAY)...
U/L TROUGH WILL PUSH ACROSS THE REGION WEDNESDAY NIGHT WITH MAIN
ENERGY REMAINING WELL NORTH OF THE FORECAST AREA. ONLY A SLIGHT
CHANCE OF A SHOWER AS AN ASSOCIATED COLD FRONT STALLS ACROSS NORTH
FLORIDA. U/L PATTERN WILL BECOME INCREASINGLY ZONAL ACROSS THE U.S.
THURSDAY THROUGH SATURDAY. SURFACE HIGH PRESSURE WILL BUILD OVER
THE MID ATLANTIC WITH EASTERLY BOUNDARY LAYER FLOW ACROSS THE
PENINSULA. PARTLY CLOUDY MILD DRY CONDITIONS EACH DAY. PATTERN
WILL AMPLIFY ON SUNDAY WITH A TROUGH DEVELOPING OVER THE WESTERN
U.S. WHICH WILL BUILD A RIDGE OVER FLORIDA AND THE EASTERN
SEABOARD. BUILDING HEIGHTS WILL ALLOW TEMPERATURES TO CLIMB SEVERAL
DEGREES ABOVE CLIMATIC NORMALS.
&&
.AVIATION...
EASTERLY FLOW OFF THE ATLANTIC WILL GENERATE SCT CLDS 060-070 TODAY
WITH LCL BKN CIGS060 UNDER A STRONG SUBSIDENCE INVERSION.
&&
.MARINE...
A RIDGE OF HIGH PRESSURE NORTH OF THE REGION WILL PROVIDE A
CONTINUED EASTERLY FLOW THROUGH TUESDAY OVER THE COASTAL WATERS OF
THE EASTERN GULF OF MEXICO. A BRIEF PERIOD OF NEAR CAUTIONARY LEVEL
WINDS IS POSSIBLE TONIGHT...MAINLY SOUTH OF TAMPA BAY. THE LOCAL
GRADIENT AND WIND FIELDS ARE THEN EXPECTED TO WEAKEN DURING THE
MIDDLE OF THE WEEK AS A COLD FRONT APPROACHES AND WEAKENS OVER THE
NORTHEAST GULF. EASTERLY FLOW WILL THEN RE-DEVELOP FOR THE END OF
THE WEEK AS HIGH PRESSURE ONCE AGAIN BUILDS TO THE NORTH OF THE
REGION.
&&
.FIRE WEATHER...
SURFACE HIGH PRESSURE WILL RESIDE TO THE NORTH OF THE AREA THE NEXT
COUPLE OF DAYS PROVIDING AN EASTERLY FLOW AND ABUNDANT LOW LEVEL
ATLANTIC MOISTURE. A COLD FRONT WILL APPROACH FROM THE NORTHWEST
WEDNESDAY AND WEDNESDAY NIGHT...BUT IS EXPECTED TO WEAKEN WITHOUT
MUCH OVERALL INFLUENCE ON THE REGION. HIGH PRESSURE WILL ONCE AGAIN
BUILD TO OUR NORTH FOR THE END OF THE WEEK. NO SIGNIFICANT FIRE
WEATHER CONCERNS ARE ANTICIPATED THROUGH THE NEXT SEVERAL DAYS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 81 61 78 58 / 0 0 0 0
FMY 80 58 79 57 / 0 10 10 10
GIF 81 55 78 55 / 0 10 10 10
SRQ 80 58 77 58 / 0 0 0 10
BKV 81 52 78 50 / 0 10 0 0
SPG 78 63 76 62 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION/LONG TERM...OGLESBY
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
318 AM EST MON DEC 3 2012
.DISCUSSION...
TODAY-TONIGHT...THE H100-H70 RIDGE AXIS THAT HAS DOMINATED THE LCL
WX PATTERN FOR THE PAST SEVERAL DAYS HAS SHIFTED SLIGHTLY SWD IN
RESPONSE TO A SHORT WAVE TROF PUSHING OFF THE ERN SEABOARD. THIS HAS
RESULTED A LOW LVL WNDSHFT TO THE E/SE AS SEEN ON THE USAF 915HZ
PROFILER AS WELL AS THE 00Z KJAX SOUNDING. WINDS N OF SEBASTIAN
INLET HAVE DIMINISHED AS WELL WITH THE RIDGE AXIS RELOCATING TO THE
FL/GA BOARDER.
RELATIVELY HIGH MOISTURE ALONG THE E FL COAST WITH H100-H70
MEAN RH VALUES BTWN 70-80PCT...H100-H85 VALUES ABV 85PCT. EVEN
SO...RADAR HAS SEEN NIL PRECIP OVER THE PAST FEW HRS OUTSIDE OF THE
GULF STREAM. FURTHERMORE...LATEST RAP ANALYSIS SHOWS UPSTREAM
MOISTURE DIMINISHING TO AOB 50PCT THRU THE H100-H70 LYR WITH SINKING
MID/UPR LVL AIR (MID LVL OMEGA POSITIVE...UPR LVL DIVERGENCE
NEGATIVE). SAT TREND CONFIRMS THIS WITH DIMINISHING STRATOCU LYR
ARND THE LAKE OKEECHOBEE REGION.
MOS GUIDANCE KEEPS PRECIP CHANCES IN THE SINGLE DIGITS THRU 12Z TUE
WITH SFC DEWPOINTS FALLING INTO THE M/U50S...GFS MODEL SOUNDINGS
MAINTAIN A STOUT H85-H70 SUBSIDENCE INVERSION WITH PWAT VALUES
FALLING TO 0.7"-0.8". CAN SEE NO REASON TO QUESTION THE OUTPUT...
WILL KEEP THE FCST DRY. LITTLE CHANGE IN TEMPS FROM THE PAST FEW
DAYS AS THE PERSISTENT ONSHORE FLOW KEEPS CENTRAL FL BATHED IN WARM
OCEAN MODIFIED AIR. MAXES M/U70S COAST...L80S INTERIOR. MINS L/M60S
COAST...M/U50S INTERIOR.
TUE-FRI...HIGH PRESSURE RIDGE WILL PERSIST INTO TUESDAY THEN
WEAKEN BY WEDNESDAY AS A SHORTWAVE APPROACHES. ASSOCIATED SURFACE
FRONTAL BOUNDARY WILL REACH INTO NORTH FLORIDA BEFORE DIMINISHING
MID WEEK WITH HIGH PRESSURE TO THE NORTH BRIDGING THE BOUNDARY INTO
THURSDAY AND FRI. MAY HAVE ISOLATED COASTAL SHOWERS TUES NIGHT...
MAINLY TREASURE COAST...THEN LOW POPS MAINLY NORTHERN COASTAL
COUNTIES BY LATE THURS INTO FRI WITH SOME INCREASED MOISTURE ALONG
THE BOUNDARY AND ONSHORE FLOW. TEMPS WILL REMAIN A LITTLE ABOVE
EARLY DEC CLIMO NORMS THROUGH THE LATE WEEK WITH HIGHS IN THE
MID/UPPER 70S. OVERNIGHT LOWS RANGING FROM MID/UPPER 50S OVER
NORTHERN AND INTERIOR SECTIONS...AND AROUND 60/LOWER 60S ALONG THE
COAST FROM BREVARD COUNTY SOUTHWARD.
SAT-SUN...INFLUENCE OF OLD FRONTAL BOUNDARY WILL WANE BY THE
UPCOMING WEEKEND AS HIGH PRESSURE TO THE NORTH SLIDES EAST OVER THE
ATLANTIC AND LOW LEVEL FLOW VEERS TOWARD A MORE SE-S COMPONENT. THIS
PATTERN WILL KEEP EC FL TEMPS WARMER THAN AVERAGE WITH SOME INTERIOR
LOCATIONS APPROACCHING 80F FOR HIGHS AND OVERNIGHT LOWS IN THE LOWER
TO MID 60S MOST AREAS. RAIN CHANCES BELOW MENTIONABLE VALUES OVER
THE WEEKEND...BUT STILL SOME INDICATION BY MEDIUM RANGE MODELS THAT
RAIN CHANCES MAY GO UP EARLY NEXT WEEK...BUT BEYOND DAY 7 FORECAST.
&&
.AVIATION...THRU 04/00Z...VFR ALL SITES...CIGS BTWN FL060-080 THRU
03/16Z.
&&
.MARINE...TODAY-TONIGHT...HIGH PRES RIDGE DRIFTING DOWN THE ERN
SEABOARD WILL FORCE WINDS TO VEER TO THE E/SE AND DIMINISH. LATEST
DATA BUOY/C-MAN OBS SHOW THIS TREND ALREADY TAKING PLACE ACRS THE
LCL ATLC N OF SEBASTIAN INLET. SEAS REMAIN ARND 6FT...JUST BLO SCA
CRITERIA... LARGELY DUE TO A 4-5FT LONG PD SWELL. THE E/NE FETCH N
OF THE BAHAMAS LENGTH REMAINS QUITE LONG...THOUGH WITH THE RIDGE
PUSHING S IT WILL GRADUALLY LOSE ITS ABILITY TO MAINTAIN THE
INCOMING SWELL TRAIN. WILL CANCEL THE SCA OVER THE OFFSHORE WATERS
AND REPLACE IT WITH A CAUTIONARY STATEMENT FOR SEAS.
TUE-FRI...ONSHORE FLOW WILL PERSIST INTO THE LATE WEEK. WIND SPEEDS
GRADUALLY DECREASE INTO THE MID WEEK BUT THEN PICK UP AGAIN HEADING
INTO THE LATE WEEK WITH HIGH PRESSURE BRIDGING OLD FRONTAL BOUNDARY
AND CAUTIONARY HEADLINES MAY AGAIN BE NEEDED OVER A PORTION OF THE
LOCAL WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 76 60 75 56 / 10 0 10 10
MCO 79 58 78 56 / 10 0 10 10
MLB 77 62 75 60 / 0 0 10 20
VRB 77 62 76 59 / 0 0 10 20
LEE 78 57 77 55 / 10 0 0 10
SFB 79 58 78 57 / 10 0 10 10
ORL 79 58 78 57 / 10 0 10 10
FPR 77 61 75 59 / 0 0 10 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM....GLITTO
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
300 AM EST MON DEC 3 2012
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOW A GENERALLY UNAMPLIFIED
UPPER LEVEL PATTERN ACROSS THE CONUS. NORTHERN STREAM FLOW IS
COMPRISED OF SHORTWAVE ENERGY EJECTING EASTWARD FROM THE
INTER-MOUNTAIN WEST FOLLOWED DOWNSTREAM BY LONGWAVE RIDGING OVER THE
MIDWEST...AND THEN FINALLY ANOTHER SHORTWAVE TROUGH EXITING THE NEW
ENGLAND STATES TOWARD THE CANADIAN MARITIMES. CLOSER TO HOME...OUR
FORECAST AREA RESIDES UNDER WEAK UPPER RIDGING COVERING THE GULF OF
MEXICO/SE CONUS. THE INFLUENCE OF THIS RIDGING CAN BE SEEN ON THE
03/00Z KTBW SOUNDING PROFILE...WHICH SHOWED A WELL-DEFINED
SUBSIDENCE INVERSION AT AROUND 800MB. A RATHER DRY MID/UPPER LEVEL
COLUMN ABOVE THIS FEATURE RESULTED IN A PW VALUE OF UNDER 1".
AT THE SURFACE...HIGH PRESSURE IS IN CONTROL OF THE REGION WITH A
SURFACE RIDGE AXIS EXTENDING FROM OFF THE SE CONUS COAST BACK
WESTWARD THROUGH SOUTHERN GA/AL. GRADIENT AROUND THIS RIDGE
CONTINUES TO PROVIDE THE REGION WITH AN EASTERLY LOW LEVEL FLOW.
THIS FLOW IS BRINGING WITH IT AMPLE BOUNDARY LAYER MOISTURE THIS
MORNING. SCT-BK CLOUDS RESULTING FROM THIS MOISTURE ARE OCCASIONALLY
WORKING THEIR WAY WESTWARD ACROSS THE PENINSULA. AREAS OF FOG HAVE
BEGUN TO DEVELOP TO THE NORTH OF TAMPA BAY AND WILL HIGHLIGHT SOME
DENSE FOG POTENTIAL IN THE GRIDS FOR THE NATURE COAST ZONES...
ESPECIALLY NORTH OF BROOKSVILLE.
&&
.SHORT TERM (TODAY THROUGH WEDNESDAY)...
TODAY/TONIGHT/TUESDAY...STACKED RIDGING AND LARGE SCALE SUPPRESSION
WILL BE THE DOMINANT PLAYER IN OUR WEATHER THROUGH TUESDAY. UPPER
LEVEL RIDGE WILL EVEN SHARPEN SOMEWHAT DURING THE NEXT 24 HOURS IN
RESPONSE TO HEIGHT FALLS SPREADING EASTWARD OVER THE SOUTHERN
PLAINS. THE FORECAST UNDER THIS PATTERN WILL BE GENERALLY DRY WITH
ABOVE NORMAL TEMPERATURES. TYPICAL OF THIS TYPE OF EASTERLY FLOW
PATTERN...WILL CONTINUE TO SEE SHALLOW SPEED CONVERGENCE FOCUS
SHOWERS FORMING FROM TIME TO TIME ALONG THE EAST COAST OF FLORIDA...
AND THEN HEADING INLAND. THE MAJORITY OF THIS LIGHT SHOWER/SPRINKLE
ACTIVITY WILL DISSIPATE BEFORE REACHING OUR ZONES...HOWEVER A FEW
ISOLATED CELLS CAN NOT BE RULED OUT THIS FAR WEST. THE CHANCE OF ANY
MEASURABLE RAINFALL IS VERY LOW DUE TO THE EXTREMELY SHALLOW NATURE
OF THE AVAILABLE MOISTURE. SIMILAR DIURNAL MIXING HEIGHTS TO WHAT
OCCURRED SUNDAY ARE ANTICIPATED THE NEXT COUPLE OF DAYS. MIXING TO
BETWEEN 875-850MB TODAY AND TUESDAY WILL YIELD HIGH TEMPERATURES
INTO THE UPPER 70S/LOW 80 FOR MANY LOCATIONS. LOW TEMP RANGE BY
SUNRISE FROM THE LOWER 50S AT NORMALLY COLDER INLAND SPOTS TO LOWER
60S AT NORMALLY WARMER COASTAL LOCATIONS.
TUESDAY NIGHT/WEDNESDAY...UPPER RIDGE OVER THE FL PENINSULA RAPIDLY
BREAKS DOWN TUESDAY NIGHT/EARLY WEDNESDAY AS SHORTWAVE ENERGY
APPROACHES AND OVERSPREAD THE REGION FROM THE NORTHWEST. GLOBAL
GUIDANCE CONTINUES TO EVOLVE THE DETAILS OF THIS ENERGY SLIGHTLY
DIFFERENT...WITH THE GFS FURTHER NORTH AND MORE PROGRESSIVE THAN THE
ECMWF. SURFACE COLD FRONT ASSOCIATED WITH THIS ENERGY WILL ALSO BE
APPROACHING FROM THE NORTHWEST. SIMILAR TO THE PAST SEVERAL
FRONTS...THIS BOUNDARY LOOKS TO "LOSE STEAM" AND BEGIN TO WASH OUT
AS IT REACHES THE I-10 CORRIDOR LATE WEDNESDAY. DESPITE AT LEAST
SOME DEEP LAYER QG FORCING/SYNOPTIC SUPPORT AHEAD OF THE SHORTWAVE
DURING THE DAY ON WEDNESDAY...THE LACK OF COINCIDENT COLUMN MOISTURE
AND FADING FRONTAL FOCUS IN THE LOWER LEVELS WILL LIKELY KEEP RAIN
CHANCES LOW. A FEW ISOLATED SHOWERS/SPRINKLES SHOULD BE IN THE AREA
WEDNESDAY...HOWEVER...IMPACTS WILL BE VERY MINOR/NIL WITH REGARDS TO
OUTDOOR ACTIVITIES...AND WILL KEEP POPS AT AROUND 10%. LOWERED
HEIGHTS AND THE POTENTIAL FOR MORE CLOUDS AHEAD OF THE SHORTWAVE
WOULD KEEP DAYTIME TEMPS DOWN A FEW DEGREES FROM PREVIOUS DAYS...BUT
SHOULD NOT SEE ANY SIGNIFICANT DEPARTURES ON EITHER SIDE OF NORMAL.
&&
.LONG TERM (THURSDAY THROUGH NEXT SUNDAY)...
U/L TROUGH WILL PUSH ACROSS THE REGION WEDNESDAY NIGHT WITH MAIN
ENERGY REMAINING WELL NORTH OF THE FORECAST AREA. ONLY A SLIGHT
CHANCE OF A SHOWER AS AN ASSOCIATED COLD FRONT STALLS ACROSS NORTH
FLORIDA. U/L PATTERN WILL BECOME INCREASINGLY ZONAL ACROSS THE U.S.
THURSDAY THROUGH SATURDAY. SURFACE HIGH PRESSURE WILL BUILD OVER
THE MID ATLANTIC WITH EASTERLY BOUNDARY LAYER FLOW ACROSS THE
PENINSULA. PARTLY CLOUDY MILD DRY CONDITIONS EACH DAY. PATTERN
WILL AMPLIFY ON SUNDAY WITH A TROUGH DEVELOPING OVER THE WESTERN
U.S. WHICH WILL BUILD A RIDGE OVER FLORIDA AND THE EASTERN
SEABOARD. BUILDING HEIGHTS WILL ALLOW TEMPERATURES TO CLIMB SEVERAL
DEGREES ABOVE CLIMATIC NORMALS.
&&
.AVIATION...
EASTERLY FLOW OFF THE ATLANTIC WILL GENERATE SCT CLDS 060-070 TODAY
WITH LCL BKN CIGS060 UNDER A STRONG SUBSIDENCE INVERSION.
&&
.MARINE...
A RIDGE OF HIGH PRESSURE NORTH OF THE REGION WILL PROVIDE A
CONTINUED EASTERLY FLOW THROUGH TUESDAY OVER THE COASTAL WATERS OF
THE EASTERN GULF OF MEXICO. A BRIEF PERIOD OF NEAR CAUTIONARY LEVEL
WINDS IS POSSIBLE TONIGHT...MAINLY SOUTH OF TAMPA BAY. THE LOCAL
GRADIENT AND WIND FIELDS ARE THEN EXPECTED TO WEAKEN DURING THE
MIDDLE OF THE WEEK AS A COLD FRONT APPROACHES AND WEAKENS OVER THE
NORTHEAST GULF. EASTERLY FLOW WILL THEN RE-DEVELOP FOR THE END OF
THE WEEK AS HIGH PRESSURE ONCE AGAIN BUILDS TO THE NORTH OF THE
REGION.
&&
.FIRE WEATHER...
SURFACE HIGH PRESSURE WILL RESIDE TO THE NORTH OF THE AREA THE NEXT
COUPLE OF DAYS PROVIDING AN EASTERLY FLOW AND ABUNDANT LOW LEVEL
ATLANTIC MOISTURE. A COLD FRONT WILL APPROACH FROM THE NORTHWEST
WEDNESDAY AND WEDNESDAY NIGHT...BUT IS EXPECTED TO WEAKEN WITHOUT
MUCH OVERALL INFLUENCE ON THE REGION. HIGH PRESSURE WILL ONCE AGAIN
BUILD TO OUR NORTH FOR THE END OF THE WEEK. NO SIGNIFICANT FIRE
WEATHER CONCERNS ARE ANTICIPATED THROUGH THE NEXT SEVERAL DAYS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 81 61 78 58 / 0 0 0 0
FMY 80 58 79 57 / 0 10 10 10
GIF 81 55 78 55 / 0 10 10 10
SRQ 80 58 77 58 / 0 0 0 10
BKV 81 52 78 50 / 0 10 0 0
SPG 78 63 76 62 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION/LONG TERM...OGLESBY
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1000 PM EST TUE DEC 4 2012
.UPDATE...
NO CHANGES PLANNED FOR THE FORECAST AT THIS TIME. RAIN SHOULD
GRADUALLY SPREAD ACROSS NORTH GEORGIA OVERNIGHT...HOWEVER RAINFALL
AMOUNTS SHOULD BE LIGHT.
41
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
MAIN FORECAST PROBLEM THROUGH WEDNESDAY IS LIKELIHOOD FOR MEASURABLE
PRECIP. SHORT WAVE CURRENTLY LOCATED OVER SE OK/NRN TX ON WV IMAGERY
TRACKING EAST WITH CONSIDERABLE AMOUNT OF DEEP CONVECTION OCCURRING
AHEAD OF THE WAVE OVER THE LOWER MS VALLEY. MODELS HAVE VERY GOOD
AGREEMENT ON TIMING OF WAVE AND ASSOCIATED FRONT MOVING INTO THE FAR
NORTH LATE TONIGHT. MODELS ALSO IN STRONG AGREEMENT THAT VERTICAL
LIFT WILL WEAKEN TONIGHT AND WEDNESDAY WITH MUCH LOWER PRECIP
AMOUNTS AS THE SYSTEM MOVES INTO THE STATE. ALWAYS A CHALLENGE TO
FORECAST POPS IN THIS SITUATION AS WILL LIKELY SEE SCT LIGHT SHOWERS
ACROSS NORTHERN 3/4THS OF CWA BUT NOT CONFIDENT THAT ALL THESE
SHOWERS WILL PRODUCE MEASURABLE RAINFALL. HAVE KEPT POPS LATE
TONIGHT AND WED CONFINED TO LKLY CATEGORY OVER AREAS NORTH OF ATL
METRO AND 40-60 OVER METRO AND MUCH OF MIDDLE GA. NEAR-TERM MODELS
INCLUDING RADAR ASSIMILATING MODELS SUCH AS THE HRRR ARE INDICATING
BEST CHC FOR RAIN IN THE ATL METRO AROUND 6-8AM WITH LINGERING CHC
OF SCT LIGHT SHOWERS DURING THE DAY. USED MAV/MET BLEND FOR TEMPS
WITH A SLIGHT UPWARD ADJUSTMENT FOR MIN TEMPS TONIGHT.
BY WED...SUBSIDENCE BEHIND STRONG WAVE OVER THE NORTHEAST CONUS
YIELDS A EXPANSIVE 1035MB SFC HIGH OVER THE MIDWEST WHICH IS PROGGED
TO SPILL OVER AND DAM UP ALONG THE APPALACHIANS. SIGNIFICANT WEDGE
EVENT SHOULD RESULT BUT AS MENTIONED EARLIER...WE ARE FORTUNATE THAT
THE SOURCE AIRMASS FOR THIS HIGH IS NOT ARCTIC OR THAT COLD.
OTHERWISE WE MIGHT BE IN A WORLD OF HURT. OTHER THAN SOME COOL EAST
WINDS AND SOME PATCHY LIGHT RAIN AND FAIRLY WIDESPREAD CLOUDS...
SHOULD NOT BE TOO BAD FOR DECEMBER.
SNELSON
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
OVERALL...PREVIOUS FORECAST LOOKS TO BE ON TRACK. HAVE CONTINUED
WITH SLIGHT CHANCE POPS AS THE WEDGE REMAINS IN PLACE THROUGH LATE
WEEK WITH MODELS STILL INDICATING ISENTROPIC LIFT AND UPSLOPE FLOW
WILL SUPPORT LIGHT RAIN. MODEL GUIDANCE HAVE WARMED SLIGHTLY
DURING THE CAD EVENT...AND HAVE INCREASED MORNING LOW TEMPERATURES
SLIGHTLY FOR BETTER CONSISTENCY WITH THE SURROUNDING OFFICES. FOR
NOW...HAVE MADE A FEW VERY MINOR TWEAKS TO HIGH TEMPERATURE...BUT
OVERALL THINK THE MODELS ARE TOO WARM. THERE IS STILL ENOUGH
UNCERTAINTY WITH LATE WEEKEND AND EARLY WEEK MODEL SOLUTIONS THAT
HAVE OPTED NOT TO MAKE ANY SIGNIFICANT CHANGES AT THIS TIME.
HAVE INCLUDED THE PREVIOUS DISCUSSION BELOW.
31
ISSUED 356 AM EST TUE DEC 4 2012/
FRONT IMPACTING NORTH GEORGIA DURING THE SHORT TERM WILL BRIEFLY
STALL OUT ACROSS CENTRAL GEORGIA WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS BOUNDARY WILL PUSH FARTHER SOUTH AND WEST AS A WEDGE
FRONT ON THURSDAY DUE TO HYBRID CAD FROM A 1027 MB PARENT HIGH OFF
THE MID- ATLANTIC COAST. HAVE INCLUDED SLIGHT POPS FOR SHOWERS AS
THIS BOUNDARY INTERACTS WITH OVERRUNNING MOISTURE FROM THE SOUTH.
GUIDANCE SUGGESTS CONTINUED ISENTROPIC UPGLIDE ACROSS MUCH OF THE
AREA THROUGH FRIDAY SO HAVE KEPT SLIGHT CHANCE POPS FOR SHOWERS
FOR THE MAJORITY OF THE CWA AND MOSTLY CLOUDY SKIES DURING THIS
PERIOD. ANY ENHANCED SOLAR SHELTERING ACROSS THE CAD DOME MAY
REINFORCE THE WEDGE AND LEAD TO LATER EROSION THAN WHAT GUIDANCE
SUGGESTS... POSSIBLY LINGERING INTO THE WEEKEND. THIS WILL NEED TO
BE MONITORED CLOSER AS THIS FEATURE GETS INCLUDED IN THE SHORT
TERM MODELS.
BROAD SW FLOW ALOFT SETS UP FOR THE WEEKEND AND A STATIONARY FRONT
LOOKS TO BECOME SITUATED NW OF THE AREA ACROSS THE TN AND OHIO RIVER
VALLEYS. THE GFS AND ECMWF DIFFER GREATLY IN THE STRENGTH OF THE
BAROCLINITY AND EXPANSE OF THE MOISTURE FIELD WITH THIS
FEATURE...THOUGH SOME SHOWER DEVELOPMENT IS POSSIBLE ACROSS NORTH
GEORGIA IF ENOUGH MOISTURE EXISTS WITH SOME OROGRAPHIC ENHANCEMENT
DUE TO SOUTHERLY/SOUTHWESTERLY LOW LEVEL FLOW. HAVE THEREFORE KEPT
SLIGHT TO LOW END CHANCE POPS FOR SHOWERS ACROSS THE NORTHERN
PORTION THROUGH THE WEEKEND.
THE LATEST RUNS OF THE GFS AND ECMWF ARE IN DECENT AGREEMENT WITH
THE NEXT SIGNIFICANT PIECE OF ENERGY SWINGING ACROSS THE SOUTHWEST
CONUS AS AN UPPER CUTOFF LOW BY SUNDAY INTO MONDAY...THEN LIFTING
NORTHEASTWARD ACROSS THE CENTRAL PLAINS BY MONDAY NIGHT INTO
TUESDAY. A STRONG COLD FRONT ASSOCIATED WITH THE PHASED SFC LOW
PRESSURE SYSTEM MAY APPROACH THE FORECAST AREA FROM THE WEST BY
TUESDAY...HOWEVER THIS IS JUST BEYOND THE END OF THE FORECAST PERIOD
AND WILL ADJUST AS NECESSARY IN FUTURE UPDATES.
FORECAST INSTABILITY IS TOO LOW TO INCLUDE ANY THUNDER CHANCES IN
THE LONG TERM...THOUGH THE BEST SHOT LOOKS TO BE WITH POTENTIAL CFP
NEAR THE END OF THE FORECAST PERIOD EARLY NEXT WEEK.
BAKER
&&
.AVIATION...
00Z UPDATE...
CEILINGS 050 TO 070 PERSISTING OVERNIGHT WITH SOME MVFR DEVELOPING
AFTER 10Z WITH CONTINUED MOIST SOUTHERLY FLOW. SHOWERS SHOULD REMAIN
WEST OF MOST TAF SITES AROUND 12Z...WITH RAIN SLOW TO SPREAD INTO
CENTRAL GA. INSTABILITY WILL BE VERY MARGINAL SO LITTLE THREAT FOR
THUNDER. FRONT WILL BECOME STATIONARY ACROSS THE STATE WEDNESDAY SO
SW TO WEST SFC WINDS WILL CONTINUE. HIGH PRESSURE BUILDING DOWN THE
EAST COAST SHOULD TURN WINDS TO NORTHEAST TOWARD THE END OF THE TAF
PERIOD.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM CONFIDENCE ON MVFR CIGS AND TIMING OF BEGINNING OF RAIN.
MEDIUM TO HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
41
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 53 68 50 57 / 40 50 30 20
ATLANTA 56 67 51 60 / 50 60 20 20
BLAIRSVILLE 51 63 44 55 / 60 60 20 20
CARTERSVILLE 53 66 48 61 / 60 60 20 20
COLUMBUS 55 74 54 69 / 30 30 10 20
GAINESVILLE 54 65 49 56 / 50 60 30 20
MACON 52 74 51 65 / 20 20 20 20
ROME 52 67 47 62 / 60 60 20 20
PEACHTREE CITY 51 67 48 62 / 50 60 20 20
VIDALIA 53 75 54 67 / 10 20 10 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....31
AVIATION...41
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
640 PM EST TUE DEC 4 2012
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
MAIN FORECAST PROBLEM THROUGH WEDNESDAY IS LIKELIHOOD FOR MEASURABLE
PRECIP. SHORT WAVE CURRENTLY LOCATED OVER SE OK/NRN TX ON WV IMAGERY
TRACKING EAST WITH CONSIDERABLE AMOUNT OF DEEP CONVECTION OCCURRING
AHEAD OF THE WAVE OVER THE LOWER MS VALLEY. MODELS HAVE VERY GOOD
AGREEMENT ON TIMING OF WAVE AND ASSOCIATED FRONT MOVING INTO THE FAR
NORTH LATE TONIGHT. MODELS ALSO IN STRONG AGREEMENT THAT VERTICAL
LIFT WILL WEAKEN TONIGHT AND WEDNESDAY WITH MUCH LOWER PRECIP
AMOUNTS AS THE SYSTEM MOVES INTO THE STATE. ALWAYS A CHALLENGE TO
FORECAST POPS IN THIS SITUATION AS WILL LIKELY SEE SCT LIGHT SHOWERS
ACROSS NORTHERN 3/4THS OF CWA BUT NOT CONFIDENT THAT ALL THESE
SHOWERS WILL PRODUCE MEASURABLE RAINFALL. HAVE KEPT POPS LATE
TONIGHT AND WED CONFINED TO LKLY CATEGORY OVER AREAS NORTH OF ATL
METRO AND 40-60 OVER METRO AND MUCH OF MIDDLE GA. NEAR-TERM MODELS
INCLUDING RADAR ASSIMILATING MODELS SUCH AS THE HRRR ARE INDICATING
BEST CHC FOR RAIN IN THE ATL METRO AROUND 6-8AM WITH LINGERING CHC
OF SCT LIGHT SHOWERS DURING THE DAY. USED MAV/MET BLEND FOR TEMPS
WITH A SLIGHT UPWARD ADJUSTMENT FOR MIN TEMPS TONIGHT.
BY WED...SUBSIDENCE BEHIND STRONG WAVE OVER THE NORTHEAST CONUS
YIELDS A EXPANSIVE 1035MB SFC HIGH OVER THE MIDWEST WHICH IS PROGGED
TO SPILL OVER AND DAM UP ALONG THE APPALACHIANS. SIGNIFICANT WEDGE
EVENT SHOULD RESULT BUT AS MENTIONED EARLIER...WE ARE FORTUNATE THAT
THE SOURCE AIRMASS FOR THIS HIGH IS NOT ARCTIC OR THAT COLD.
OTHERWISE WE MIGHT BE IN A WORLD OF HURT. OTHER THAN SOME COOL EAST
WINDS AND SOME PATCHY LIGHT RAIN AND FAIRLY WIDESPREAD CLOUDS...
SHOULD NOT BE TOO BAD FOR DECEMBER.
SNELSON
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
OVERALL...PREVIOUS FORECAST LOOKS TO BE ON TRACK. HAVE CONTINUED
WITH SLIGHT CHANCE POPS AS THE WEDGE REMAINS IN PLACE THROUGH LATE
WEEK WITH MODELS STILL INDICATING ISENTROPIC LIFT AND UPSLOPE FLOW
WILL SUPPORT LIGHT RAIN. MODEL GUIDANCE HAVE WARMED SLIGHTLY
DURING THE CAD EVENT...AND HAVE INCREASED MORNING LOW TEMPERATURES
SLIGHTLY FOR BETTER CONSISTENCY WITH THE SURROUNDING OFFICES. FOR
NOW...HAVE MADE A FEW VERY MINOR TWEAKS TO HIGH TEMPERATURE...BUT
OVERALL THINK THE MODELS ARE TOO WARM. THERE IS STILL ENOUGH
UNCERTAINTY WITH LATE WEEKEND AND EARLY WEEK MODEL SOLUTIONS THAT
HAVE OPTED NOT TO MAKE ANY SIGNIFICANT CHANGES AT THIS TIME.
HAVE INCLUDED THE PREVIOUS DISCUSSION BELOW.
31
ISSUED 356 AM EST TUE DEC 4 2012/
FRONT IMPACTING NORTH GEORGIA DURING THE SHORT TERM WILL BRIEFLY
STALL OUT ACROSS CENTRAL GEORGIA WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS BOUNDARY WILL PUSH FARTHER SOUTH AND WEST AS A WEDGE
FRONT ON THURSDAY DUE TO HYBRID CAD FROM A 1027 MB PARENT HIGH OFF
THE MID- ATLANTIC COAST. HAVE INCLUDED SLIGHT POPS FOR SHOWERS AS
THIS BOUNDARY INTERACTS WITH OVERRUNNING MOISTURE FROM THE SOUTH.
GUIDANCE SUGGESTS CONTINUED ISENTROPIC UPGLIDE ACROSS MUCH OF THE
AREA THROUGH FRIDAY SO HAVE KEPT SLIGHT CHANCE POPS FOR SHOWERS
FOR THE MAJORITY OF THE CWA AND MOSTLY CLOUDY SKIES DURING THIS
PERIOD. ANY ENHANCED SOLAR SHELTERING ACROSS THE CAD DOME MAY
REINFORCE THE WEDGE AND LEAD TO LATER EROSION THAN WHAT GUIDANCE
SUGGESTS... POSSIBLY LINGERING INTO THE WEEKEND. THIS WILL NEED TO
BE MONITORED CLOSER AS THIS FEATURE GETS INCLUDED IN THE SHORT
TERM MODELS.
BROAD SW FLOW ALOFT SETS UP FOR THE WEEKEND AND A STATIONARY FRONT
LOOKS TO BECOME SITUATED NW OF THE AREA ACROSS THE TN AND OHIO RIVER
VALLEYS. THE GFS AND ECMWF DIFFER GREATLY IN THE STRENGTH OF THE
BAROCLINITY AND EXPANSE OF THE MOISTURE FIELD WITH THIS
FEATURE...THOUGH SOME SHOWER DEVELOPMENT IS POSSIBLE ACROSS NORTH
GEORGIA IF ENOUGH MOISTURE EXISTS WITH SOME OROGRAPHIC ENHANCEMENT
DUE TO SOUTHERLY/SOUTHWESTERLY LOW LEVEL FLOW. HAVE THEREFORE KEPT
SLIGHT TO LOW END CHANCE POPS FOR SHOWERS ACROSS THE NORTHERN
PORTION THROUGH THE WEEKEND.
THE LATEST RUNS OF THE GFS AND ECMWF ARE IN DECENT AGREEMENT WITH
THE NEXT SIGNIFICANT PIECE OF ENERGY SWINGING ACROSS THE SOUTHWEST
CONUS AS AN UPPER CUTOFF LOW BY SUNDAY INTO MONDAY...THEN LIFTING
NORTHEASTWARD ACROSS THE CENTRAL PLAINS BY MONDAY NIGHT INTO
TUESDAY. A STRONG COLD FRONT ASSOCIATED WITH THE PHASED SFC LOW
PRESSURE SYSTEM MAY APPROACH THE FORECAST AREA FROM THE WEST BY
TUESDAY...HOWEVER THIS IS JUST BEYOND THE END OF THE FORECAST PERIOD
AND WILL ADJUST AS NECESSARY IN FUTURE UPDATES.
FORECAST INSTABILITY IS TOO LOW TO INCLUDE ANY THUNDER CHANCES IN
THE LONG TERM...THOUGH THE BEST SHOT LOOKS TO BE WITH POTENTIAL CFP
NEAR THE END OF THE FORECAST PERIOD EARLY NEXT WEEK.
BAKER
&&
.AVIATION...
00Z UPDATE...
CEILINGS 050 TO 070 PERSISTING OVERNIGHT WITH SOME MVFR DEVELOPING
AFTER 10Z WITH CONTINUED MOIST SOUTHERLY FLOW. SHOWERS SHOULD REMAIN
WEST OF MOST TAF SITES AROUND 12Z...WITH RAIN SLOW TO SPREAD INTO
CENTRAL GA. INSTABILITY WILL BE VERY MARGINAL SO LITTLE THREAT FOR
THUNDER. FRONT WILL BECOME STATIONARY ACROSS THE STATE WEDNESDAY SO
SW TO WEST SFC WINDS WILL CONTINUE. HIGH PRESSURE BUILDING DOWN THE
EAST COAST SHOULD TURN WINDS TO NORTHEAST TOWARD THE END OF THE TAF
PERIOD.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM CONFIDENCE ON MVFR CIGS AND TIMING OF BEGINNING OF RAIN.
MEDIUM TO HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
41
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 53 68 50 57 / 40 50 30 20
ATLANTA 56 67 51 60 / 50 60 20 20
BLAIRSVILLE 51 63 44 55 / 60 60 20 20
CARTERSVILLE 53 66 48 61 / 60 60 20 20
COLUMBUS 55 74 54 69 / 30 30 10 20
GAINESVILLE 54 65 49 56 / 50 60 30 20
MACON 52 74 51 65 / 20 20 20 20
ROME 52 67 47 62 / 60 60 20 20
PEACHTREE CITY 51 67 48 62 / 50 60 20 20
VIDALIA 53 75 54 67 / 10 20 10 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....31
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
308 PM CST MON DEC 3 2012
.SYNOPSIS...
A COLD FRONT WAS PUSHING INTO CENTRAL IOWA WITH SOUTHERLY WINDS
TRANSPORTING UNSEASONABLY WARM AND HUMID AIR INTO THE DVN CWA.
RECORD HIGHS HAVE ALREADY BEEN SET OR TIED FOR DECEMBER 3 AT ALL
MAJOR CLIMATE SITES. TEMPERATURES WERE ALSO NEARING THE ALL-TIME
RECORD HIGHS FOR DECEMBER. CURRENT READINGS WERE IN THE MID 60S TO
LOWER 70S WITH DEW POINTS AROUND 60. SPC MESO ANALYSIS INDICATED
SBCAPES WERE 500 J/KG AND EFFECTIVE BULK SHEAR WAS 45 KTS EAST OF
THE MS RIVER. EXTENSIVE LOW CLOUDS WERE OVER THE CWA BUT SOME
BREAKS NOTED ON VISIBLE SATELLITE PICTURES. ELSEWHERE BEHIND THE
FRONT TEMPERATURES WERE IN THE 50S WITH DEW POINTS IN THE
TEENS...ALONG WITH SUNNY SKIES.
HAASE
&&
.SHORT TERM...TONIGHT AND TUESDAY...
FORECAST FOCUS ON CONVECTIVE TRENDS LATE THIS AFTERNOON/EARLY THIS
EVENING WITH COLD FRONT.
TONIGHT...LOW CLOUDS PUTTING A DAMPER ON THE CONVECTIVE THREAT BUT
WILL STILL MENTION SHOWERS LIKELY AND ISOLATED THUNDERSTORMS FROM
MAINLY ABOUT THE MS RIVER ON EAST INTO THIS EVENING. HRRR MESO
MODEL SEEMS REASONABLE. THE COLD FRONT SHOULD BE NEAR THE MS RIVER
ABOUT 6 PM AND WILL HAVE MOVED THROUGH ALL OF THE CWA BEFORE
MIDNIGHT SO WILL BE DRY AFTER MIDNIGHT. SKIES WILL CLEAR LATER
TONIGHT AS SUBSIDENCE BEHIND UPPER TROUGH SWINGS THROUGH. WILL BE
COLDER WITH MIN TEMPS IN THE MID 30S NW TO MID 40S SE.
TUESDAY...HIGH PRESSURE BUILDS INTO THE CWA WITH SUNNY SKIES AND
COOLER TEMPERATURES...BUT STILL WELL ABOVE NORMAL FOR EARLY DECEMBER.
EXPECT AFTERNOON READINGS IN THE 50S ACROSS THE CWA.
HAASE
.LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
ZONAL UPPER LEVEL FLOW TO CONTINUE THE WARMER THAN NORMAL
TEMPERATURES THROUGH THE WORKWEEK WITH PRECIPITATION CHANCES FOCUSED
ON A COLD FRONTAL PASSAGE THURSDAY. THE POTENTIAL FOR MUCH COLDER
TEMPERATURES AND POSSIBLE WINTRY PRECIPITATION IS STARTING TO LOOK
MORE LIKELY WITH THE ARRIVAL OF A MORE DYNAMIC PATTERN OVER THE
WEEKEND INTO EARLY NEXT WEEK.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...HIGH PRESSURE DROPPING SOUTHEAST
OUT OF THE NORTHERN PLAINS WILL BRING A COLDER AIRMASS INTO THE
REGION TUESDAY NIGHT. CLEAR SKIES...LIGHT WINDS...AND 850 MB
TEMPERATURES IN THE LOW SINGLE DIGITS SUPPORT LOWS FROM THE MID 20S
NORTH TO LOWER 30S SOUTH. WEDNESDAY WILL REMAIN RELATIVELY COOL
COMPARED TO THE RECENT WARMTH AS LIGHT SOUTHEAST WINDS OUT OF THE
DEPARTING HIGH LIMIT HIGHS TO THE UPPER 30S NORTH TO NEAR 50 IN THE
FAR SOUTH. HIGH LEVEL CLOUD COVER WEDNESDAY WELL OUT AHEAD OF THE
NEXT FAST MOVING SHORTWAVE WILL HOLD MINS TO THE 30S.
THE FASTER ECMWF AND GEM TIMING OF THURSDAY EVENING/S COLD FRONTAL
PASSAGE IS PREFERRED OVER THE SLOWER GFS IN THE FAST FLOW ALOFT. MODELS
HAVE BACKED OFF SOME ON THE EXTENT OF PREFRONTAL PRECIPITATION...AND
HAVE FOLLOWED BY CONFINING LOW CHANCES FOR RAIN SHOWERS TO MAINLY
THE AFTERNOON HOURS ACROSS THE NORTHWEST. OTHERWISE...IT WILL BE
ANOTHER DAY OF BRISK SOUTHERLY WINDS...CLOUD COVER AND MILD
TEMPERATURES AHEAD OF THE FRONT WITH HIGHS FROM THE UPPER 40S TO
LOWER 50S. FOLLOWING THE FASTER NON-GFS SOLUTIONS...THE FRONT SHOULD
PUSH WELL SOUTHEAST BY FRIDAY MORNING...ALLOWING A DRY NORTH TO
NORTHEAST LOW LEVEL FLOW OUT OF THE NEXT HIGH DROPPING INTO THE
NORTHERN PLAINS. HOWEVER...DUE TO THE INPUT OF THE SLOWER...MORE
NORTHERLY GFS FRONTAL SOLUTION...SLIGHT CHANCE POPS ARE CARRIED INTO
THE FRIDAY PERIOD. TEMPERATURES WILL BE NOTICEABLY COOLER AS HIGHS
RETURN TO THE 40S.
SATURDAY THROUGH MONDAY...LATEST MODEL SOLUTIONS GENERALLY AGREE ON
AN EVOLUTION TO A MORE AMPLIFIED UPPER LEVEL FLOW AS A BUILDING
RIDGE IN THE EASTERN PACIFIC INDUCES A LONGWAVE TROUGH DOWNSTREAM IN
THE WESTERN U.S. THIS SETS UP AN UPPER LEVEL SOUTHWEST FLOW OVER A
STALLED FRONTAL BOUNDARY THROUGH THE MID MS VALLEY...FAVORABLE FOR
MORE WINTRY TYPE SYSTEMS OVER THE LOCAL AREA. HOWEVER...DUE TO HIGH
MODEL VARIABILITY FROM RUN TO RUN AND BETWEEN MODELS...CONFIDENCE IN
DETAILS IN THESE PERIODS REMAINS LOW. OVER THE PAST FEW RUNS...THE
ECMWF APPEARS TO HAVE THE BEST CONTINUITY WITH ITS MORE PHASED
DEPICTION OF THE LEAD SHORTWAVES THAT COULD RESULT IN THE REGION/S
FIRST WINTER STORM SYSTEM TRACKING FROM THE SOUTHERN PLAINS INTO THE
GREAT LAKES FROM SATURDAY NIGHT THROUGH SUNDAY NIGHT. THE 12Z GFS
HAS A SIMILAR SURFACE LOW...ALTHOUGH HAS A SLIGHTLY FASTER AND MORE
NORTHERLY TRACK. FOR NOW...THE BLENDED MODEL APPROACH WILL KEEP AN
EXTENDED PERIOD OF SLIGHT TO LOW END CHANCE POPS FROM FRIDAY NIGHT
THROUGH MONDAY...WHICH WILL LIKELY BE NARROWED DOWN IN LATER
FORECASTS. ABOVE NORMAL TEMPERATURES ADVERTISED THROUGH THE WEEKEND
COULD END UP SEVERAL CATEGORIES TOO HIGH...ESPECIALLY FROM SUNDAY
INTO MONDAY.
SHEETS
&&
.AVIATION...
VFR CONDS REMAINDER OF THIS AFTERNOON THROUGH TUESDAY. A COLD
FRONT WILL MOVE THROUGH THE REGION AND SHOULD BE NEAR THE
MISSISSIPPI RIVER BY 6 PM. ISOLATED THUNDERSTORMS ARE EXPECTED TO
DEVELOP AHEAD OF THE FRONT WITH THE BEST CHANCE NEAR AND EAST OF
THE MISSISSIPPI LATE THIS AFTERNOON AND EARLY THIS EVENING. WINDS
WILL SHIFT TO THE NORTHWEST BEHIND THE FRONT AND WILL BE GUSTY
THROUGH THE EVENING HOURS. SKIES WILL CLEAR AND WINDS WILL
DIMINISH AFTER MIDNIGHT. HIGH PRESSURE WILL BRING SKC ON TUESDAY
WITH NORTHWEST WINDS AROUND 10 KNOTS.
HAASE
&&
.CLIMATE...
RECORD HIGHS FOR DECEMBER 3...
MOLINE.........69 IN 1970
CEDAR RAPIDS...64 IN 1998
DUBUQUE........64 IN 1970
BURLINGTON.....71 IN 1970
MONTHLY RECORD HIGHS...
BURLINGTON.....73 12/04/1998
CEDAR RAPIDS...69 12/04/1998
DUBUQUE........67 12/04/1998, 24/1889
MOLINE.........71 12/04/1998
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
HAASE/SHEETS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1138 AM MST MON DEC 3 2012
.UPDATE...
ISSUED AT 1137 AM MST MON DEC 3 2012
WILL LET THE WIND ADVISORY EXPIRE ON SCHEDULE AT 19Z. SURFACE
WINDS ALONG THE COLORADO/KANSAS BORDER MAY CONTINUE TO BRIEFLY
REACH ADVISORY CRITERIA FOR A FEW MORE HOURS...BUT RECENT VAD WIND
PROFILE SHOWS A 10 KNOT DECREASE OF WINDS. RUC ALSO SUPPORTS A
GRADUAL DECREASE OF WINDS AS SURFACE HIGH MOVES ACROSS WESTERN
NEBRASKA.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 330 AM MST MON DEC 3 2012
UPPER FLOW WILL BE WESTERLY AHEAD OF A RIDGE MOVING INTO THE ROCKIES
TUESDAY NIGHT. WESTERLY FLOW WILL RESUME WEDNESDAY NIGHT AS THE
RIDGE SHIFTS EAST INTO THE GREAT LAKES REGION. A SURFACE HIGH WILL
MOVE INTO THE CENTRAL PLAINS TODAY AND CONTINUE THROUGH TUESDAY. A
TROUGH WILL MOVE INTO EASTERN COLORADO TUESDAY NIGHT AND CONTINUE
THROUGH WEDNESDAY NIGHT.
SUBSIDENCE AND LACK OF MOISTURE WILL KEEP DRY CONDITIONS ONGOING
THROUGH WEDNESDAY NIGHT. POPS WILL BE NIL FROM TODAY THROUGH
WEDNESDAY NIGHT.
THE MAIN CONCERN WITH THIS PART OF THE FORECAST ARE WINDS FOR THIS
MORNING. NORTH WINDS MAY REACH ADVISORY LEVEL FOR A FEW HOURS BEFORE
NOON. SUSTAINED WIND COULD RANGE FROM 30 TO 35 MPH WITH GUSTS TO
45 MPH ACROSS EASTERN COLORADO AND THE FIRST TWO TIERS OF COUNTIES
IN NORTHWEST KANSAS/SOUTHWEST NEBRASKA. MODELS INDICATE THAT THE
WIND WILL DROP OFF RATHER QUICKLY. BASED ON UPSTREAM METARS AM
CONCERNED THAT WIND GUSTS WILL REACH WIND ADVISORY CRITERIA OF 45
MPH AND SO FOR THIS REASON WILL ISSUE A WIND ADVISORY EVEN THOUGH
IT MAY BE SHORT-LIVED. (SEE DETAILS BELOW).
MAX TEMPERATURES WILL BE COOLER TODAY BEHIND THE FRONT WITH READINGS
IN THE MID 50S ACROSS THE WESTERN FA AND LOWER 60S EAST. MAX
TEMPERATURES WILL RISE TO NEAR 60 TUESDAY AND THE MID 60S WEDNESDAY.
MIN TEMPERATURES WILL COOL TO THE MID 20S TONIGHT AND THEN MODERATE
TO THE LOWER AND MID 30S TUESDAY/WEDNESDAY NIGHTS.
.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 330 AM MST MON DEC 3 2012
FOCUS IN THE LONG TERM IS THE POSSIBILITY OF PRECIPITATION LATE IN
THE PERIOD.
A SHORT WAVE TROUGH IN THE UPPER ZONAL FLOW MOVES ACROSS THE CENTRAL
HIGH PLAINS REGION ON THURSDAY. ADDITIONAL IMPULSES MOVE THROUGH
THE UPPER FLOW AND ACROSS THE CENTRAL HIGH PLAINS REGION FRIDAY
NIGHT AND SATURDAY NIGHT AS THE UPPER FLOW BECOMES INCREASINGLY SW
AHEAD OF A LARGER SCALE TROUGH DEEPENING OVER THE FAR WESTERN
UNITED STATES SATURDAY AND SATURDAY NIGHT. BY SUNDAY THE GFS AND
ECMWF HAVE BECOME FURTHER APART IN TIMING THE TROUGH OVER AND EAST
OF THE ROCKIES. WITH A TENDENCY TOWARDS A SLOWER SOLUTION AS STORM
SYSTEMS MOVE FROM THE LONG TERM INTO THE SHORT TERM...WILL HOLD OFF
ON INTRODUCING ANY PRECIPITATION IN THE EXTENDED PERIOD AND WILL
KEEP THE ENTIRE EXTENDED PERIOD DRY. EXPECT A COLD FRONT TO MOVE
THROUGH THE REGION EARLY THURSDAY MORNING. HIGH TEMPERATURES ON
THURSDAY WILL BE ABOUT 10 DEGREES COOLER THAN WEDNESDAY. WITH THE
JET BEGINNING TO SAG FURTHER SOUTH...EXPECT TEMPERATURES TO REMAIN
COOLER...BUT STILL WARMER THAN AVERAGE FOR THIS TIME OF
YEAR...THROUGH THE REMAINDER OF THE WEEK AND INTO THE WEEKEND.
EXPECT THE NEXT BEST CHANCE OF PRECIPITATION AND COLDER TEMPERATURES
ACROSS THE REGION TO COME EARLY NEXT WEEK AS THE LARGER UPPER TROUGH
MOVES EAST OF THE ROCKIES AND ACROSS THE PLAINS STATES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1039 AM MST MON DEC 3 2012
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD AT BOTH GLD AND
MCK. BREEZY NORTH WINDS GUSTING TO NEAR 40KTS ARE PRESENT THIS
AFTERNOON BEHIND A COLD FRONT WHICH MOVED THROUGH EARLIER THIS
MORNING. WINDS WILL DECREASE THROUGHOUT THE REST OF THE DAY AND
SKIES WILL BE MOSTLY SUNNY WITH JUST A FEW HIGH CIRRUS. OVERNIGHT
EXPECT LIGHT AND VARIABLE WINDS AS HIGH PRESSURE BUILDS ACROSS THE
TRI- STATE REGION...WITH A FEW MID-LEVEL CLOUDS MOVING ACROSS GLD
LATE TONIGHT INTO TUESDAY MORNING.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...MENTZER
SHORT TERM...032
LONG TERM...LOCKHART
AVIATION...JJM
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1145 PM CST SUN DEC 2 2012
...UPDATE TO AVIATION...
.DISCUSSION...
SHORT TERM FORECAST (TONIGHT AND MONDAY)...
AT 21Z SURFACE OBSERVATIONS AND ASSOCIATED RAP ANALYSIS INDICATES A
DECENT PRESSURE GRADIENT FORMING ACROSS EASTERN KANSAS IN RESPONSE
TO A LEE SIDE SURFACE TROUGH FORMING ON THE EAST SIDE OF THE
ROCKIES...OVER THE CENTRAL HIGH PLAINS. THIS PRESSURE GRADIENT HAS
ALLOWED FOR SOUTHERLY FLOW TO INCREASE THROUGH OUT THE DAY AS WARM
AND MOIST AIR MOVES INTO THE AREA. ALTHOUGH DEWPOINTS THROUGHOUT THE
AREA ARE ONLY IN THE LOWER TO MID 40S OBSERVATIONS FROM ACROSS
OK..AR..AND SOUTHERN MISSOURI INDICATE THAT A DECENT AMOUNT OF LOW
LEVEL MOISTURE IN THE FORM OF UPPER 50 TO LOWER 60 DEGREE DEWPOINTS
RESIDES AND IS POISED TO MAKE A SURGE NORTHWARD AS THE PREVIOUSLY
MENTIONED TROUGH MOVES OFF THE HIGH PLAINS. DIFFICULT FORECAST
REMAINS FOR THE OVERNIGHT HOURS AS THE MOISTURE SURGES NORTH. GIVEN
THE SHALLOW NATURE OF THE GOOD MOISTURE WITH VERY DRY AIR ABOVE THE
LOW LEVEL MOISTURE WILL RULE OUT MEASURABLE PRECIPITATION FOR THE
OVERNIGHT HOURS...HOWEVER A LOW STRATUS DECK DOES SEEM RATHER LIKELY
WITH POSSIBLY SOME VERY MINOR DRIZZLE. ALSO WILL NOT RULE OUT THE
POSSIBILITY OF SOME PATCHY FOG AS SOME MODEL GUIDANCE SUGGESTS AREAS
OF REDUCED VISIBILITY...ESPECIALLY ALONG AND EAST OF HIGHWAY 75.
CANNOT COMPLETELY RULE OUT DENSE FOG OVERNIGHT...ESPECIALLY IN THE
AFOREMENTIONED FAR EASTERN KANSAS AREAS...BUT GIVEN THE FACT THAT
SOUTHERLY WINDS OF AROUND 10 TO 20 MPH WILL BE PERSISTENT FOR MUCH
OF THE NIGHT THE FEELING IS THAT THE LOWER ATMOSPHERE MAY BE TOO
MIXED TO CONSIDER WIDESPREAD DENSE FOG. LOW STRATUS/FOG WILL LIKELY
REMAIN IN THE AREA THROUGH THE MID MORNING BEFORE MIXING GRADUALLY
DISSIPATES THE STRATUS BY MID MORNING/EARLY AFTERNOON. FOR MONDAY WE
CAN EXPECT ONE MORE DAY WITH TEMPS NEARLY 25 DEGREES WARMER THAN
SEASONAL NORMALS. A COLD FRONT STANDS POISED TO MOVE THROUGH THE
AREA DURING THE DAY ON MONDAY. ALTHOUGH THIS FRONT WILL ACT TO BRING
TEMPS DOWN A FEW DEGREES IT WILL HARDLY BRING THE SURGE OF COLD AIR
TYPICALLY ASSOCIATED WITH DECEMBER AS TEMPS FOR THE MIDDLE PART OF
THE WEEK WILL REMAIN WELL ABOVE NORMAL.
JL
LONG TERM - TUESDAY THROUGH SUNDAY...
TUESDAY THROUGH WEDNESDAY NIGHT - THE COLD FRONT WILL HAVE PASSED
COMPLETELY THROUGH THE FORECAST AREA BY MONDAY EVENING AND ANY
PRECIPITATION SHOULD HAVE SHIFTED SOUTHEAST WITH THE FRONT. COLD
AND DRY ADVECTION WILL TAKE PLACE INTO TUESDAY BUT A NORTH BREEZE
OVERNIGHT WILL KEEP TUESDAY MORNING LOWS IN THE 30S AND THE WARM
START ALONG WITH DECENT MIXING SHOULD ALLOW AFTERNOON HIGHS TO
GET INTO THE LOWER 60S. RETURN FLOW WITH SOME WARM MOIST ADVECTION
WILL THEN TAKE OVER BY WEDNESDAY AS A WEAK SHORT WAVE TROUGH AND
SURFACE LOW PRESSURE MOVE INTO THE NORTHERN HIGH PLAINS. WHILE
TEMPERATURES ALOFT WILL BE WARMER ON WEDNESDAY...COULD SEE MORE IN
THE WAY OF CLOUDS AND LESS MIXING...RESULTING IN HIGHS STILL IN
THE LOWER 60S. MORE SUN COULD ALLOW HIGHS TO SNEAK INTO THE UPPER
60S IN A FEW SPOTS THOUGH. EXPECT LOW CLOUDS TO FILL IN FURTHER BY
WEDNESDAY NIGHT AS THE LOW LEVEL MOISTURE INFLUX INCREASES.
CLOUDS WILL KEEP LOWS WARMER.
THURSDAY THROUGH FRIDAY - A COLD FRONT ASSOCIATED WITH THE
NORTHERN PLAINS SHORT WAVE TROUGH WILL MOVE THROUGH THE FORECAST
AREA DURING THE DAY ON THURSDAY WITH ANOTHER ROUND OF MORE
SUBSTANTIAL COLD ADVECTION IN ITS WAKE. THERE WILL BE A DECENT
AMOUNT OF LOW LEVEL FORCING ALONG THE FRONT AND IT WILL INTERACT
WITH A FAIR AMOUNT OF GULF MOISTURE...BUT UPPER SUPPORT IS LACKING
AND SUSPECT THAT THE END RESULT MAY BE SIMILAR TO THE FRONTAL
PASSAGE ON MONDAY WITH THE BULK OF PRECIPITATION DEVELOPING
SOUTHEAST OF THE FORECAST AREA. HAVE STILL KEPT AT LEAST A CHANCE
OF SHOWERS ACROSS THE SOUTHEAST HALF OF THE FORECAST AREA FOR
UNCERTAINTY IN FRONTAL TIMING AND AT LEAST THE POTENTIAL FOR
EARLIER PRECIP DEVELOPMENT WHILE THE FRONT IS STILL IN THE LOCAL
AREA. THE BOUNDARY SHOULD PUSH SOUTHEAST OF THE FORECAST AREA BY
EARLY FRIDAY MORNING WITH A COOLER AND DRIER AIRMASS FILTERING IN.
FRIDAY NIGHT THROUGH SUNDAY - UNCERTAINTY IS HIGH DURING THIS
PERIOD REGARDING PRECIPITATION POTENTIAL WITH SIGNIFICANT MODEL
VARIANCE. MUCH OF THE VARIABILITY IS DUE TO HOW THE FLOW PATTERN
OVER THE PACIFIC OCEAN WILL EVOLVE IN THE NEXT FEW DAYS. IT DOES
APPEAR THAT A TRANSITION TO A MORE SOUTHWESTERLY FLOW PATTERN OVER
THE CENTRAL AND EASTERN CONUS WILL HAPPEN IN THE LONG TERM WITH
MOISTURE LINGERING NOT FAR TO THE SOUTH AND OCCASIONAL
DISTURBANCES INTERACTING WITH A FRONTAL BOUNDARY. HOWEVER THE
TIMING OF THE DISTURBANCES AND THE LOCATION OF THE FRONT ARE VERY
MUCH IN QUESTION. THE END RESULT FOR THIS FORECAST IS ACTUALLY FOR
COOLER...BUT NEAR NORMAL TEMPERATURES DURING THIS PERIOD WITH SOME
POTENTIAL FOR A STORM SYSTEM TO BRING PRECIPITATION TO THE REGION
BY THE WEEKEND. CURRENTLY HAVE INDICATED RAIN IN THE FORECAST...
BUT THERE WOULD BE AT LEAST SOME POTENTIAL FOR A BIT OF
SNOW...DEPENDING ON PRECIPITATION TIMING.
BARJENBRUCH
&&
.AVIATION...
LLVL MOISTURE MOVING NORTHWARD INTO SOUTHERN KS WILL SURGE BACK
INTO THE TERMINALS AFT 09Z WHICH WILL INITIALLY RESULT IN MVFR
STRATUS AND FOG FORMATION...THEN LOWER TO IFR IN KTOP/KFOE BY 11Z.
AS THE LLVL FLOW VEERS THROUGH 15Z SOUTHERLY WINDS WILL VEER TO
THE SOUTHWEST AS CIGS RISE TO AROUND 2000 FT. AS COLD FRONT APPROACHES
THEN MOVES THROUGH AND DRIER AIR ADVECTS EASTWARD...SHOULD SEE VFR
CONDITIONS SPREAD WEST TO EAST ALL AREAS IN THE 18Z-20Z TIME
FRAME WITH WINDS SHIFTING TO THE NORTHWEST 12-20 KTS.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS JACKSON KY
1050 PM EST TUE DEC 4 2012
.UPDATE...
ISSUED AT 1050 PM EST TUE DEC 4 2012
RAIN HAS FILLED BACK IN ALONG THE FRONT AND WILL ONLY NEED TO FINE
TUNE THE TIMING OF THE BACK EDGE TO THE PRECIP IN OUR HOURLY GRIDDED
DATABASE AS MAJORITY OF THE FORECAST IS ON TRACK TONIGHT. IT DOES
APPEAR BASED ON RADAR TRENDS THAT THE FRONT IS HANGING UP A BIT MORE
THAN EARLIER THOUGHT SO WILL PROLONG A SLIGHT CHANCE OF SHOWERS INTO
TOMORROW MORNING FOR OUR VA AND TN BORDER COUNTIES. OTHERWISE...NO
SUBSTANTIVE CHANGES ARE NEEDED. HAVE A GOOD NIGHT...
UPDATE ISSUED AT 823 PM EST TUE DEC 4 2012
THE COLD FRONT HAS NOW PASSED INTO OUR NORTHWEST COUNTIES HOWEVER
THE SOLID MASS OF RAINFALL THAT WAS ACCOMPANYING THE FRONT EARLIER
HAS WITHERED SUBSTANTIALLY AS IT HAS ENTERED EAST KENTUCKY. THERE IS
STILL ENOUGH PRECIP RIGHT ALONG THE FRONT TO JUSTIFY 100 POPS BUT
FORECAST QPF HAS BEEN REDUCED TO A QUARTER INCH OR LESS FOR MOST
LOCATIONS. TEMPS WILL REMAIN IN THE 60S UNTIL THE FRONT PASSES AND
THEN DROP QUICKLY THROUGH THE 50S. OUR HOURLY TEMP DATA WAS MASSAGED
USING THE RUC13 TIMING BUT THIS WILL NOT ALTER OUR MIN TEMP FORECAST
FOR NOW.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 255 PM EST TUE DEC 4 2012
SURFACE COLD FRONT IS CURRENTLY ALIGNED FROM NORTHWEST OHIO DOWN
THROUGH WESTERN KENTUCKY AND TENNESSEE. THE MAIN BAND OF
PRECIPITATION ASSOCIATED WITH THIS BOUNDARY IS STILL A FEW HOURS
AWAY...WITH MOST OF THIS ACTIVITY WORKING THROUGH IN THE 7 PM TO 12AM
TIME FRAME...AND THEN LINGERING A BIT LONGER IN THE SOUTHEAST AS THE
BOUNDARY SLOWS DOWN ALONG THE TERRAIN. EVERYONE WILL MEASURE OUT OF
THIS...SO SEE NO REASON TO NOT MAINTAIN NEAR 100 POPS. THERE HAS BEEN
SOME LIGHTNING ACTIVITY EMBEDDED WITHIN THE LINE...HOWEVER EXPECT
THESE TO WEAKEN AS IT COMES THROUGH EASTERN KENTUCKY...SO WILL LEAVE
OUT THE MENTION.
HIGH PRESSURE TRAVERSING THE GREAT LAKES AND OHIO VALLEY WILL THEN
PROVIDE DRY WEATHER ACROSS THE AREA FOR WEDNESDAY AND WEDNESDAY
NIGHT. TEMPERATURES WILL BE COOLER THAN WE HAVE BEEN SEEING
LATELY...BUT WILL STILL AVERAGE ABOVE NORMAL...WITH HIGHS GENERALLY
IN THE MID TO UPPER 50S...WITH A FEW LOWER 60S SOUTH ON WEDNESDAY.
LOWS WEDNESDAY NIGHT WILL DROP DOWN TO BELOW 30 IN SOME OF THE MORE
SHELTERED VALLEYS ALONG AND NORTH OF THE MOUNTAIN PARKWAY.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 255 PM EST TUE DEC 4 2012
MODEL PATTERN BEGINS ON THU MORNING WITH A WEAK 50H RIDGE OVER THE
NRN APPALACHIAN MTS AND NEARLY ZONAL FLOW FROM THE PLAINS TO THE
OHIO VALLEY. A WEAK AREA OF LOW PRESSURE OVER THE ERN GULF IS THE
IMPETUS FOR A FEW RETURN FLOW SHOWERS IN THE TENN VALLEY AROUND THE
BACK SIDE OF THE SFC HIGH OVER ERN PA/NY. WEATHER SHOULD REMAIN DRY
AND WARM ALTHOUGH A FEW SPRINKLES COULD BE FOUND LATE THU. BY FRI...
AN AREA OF LOW PRESSURE...ACCOMPANIED BY A LEE SIDE TROUGH...WILL
FORM IN THE SRN PLAINS. THE SFC HIGH WILL HAVE MOVED TO THE ATLANTIC
AND A WARM FRONT WILL BEGIN FORMING FROM OK TO PA. LIFT OVER THE
WARM FRONT FROM THE PREVAILING SOUTHERLY WIND WILL CAUSE A BETTER
CHANCE OF PCPN TO FORM OVER THE OHIO RIVER WITH A GOOD CHANCE OF
RAIN OVER OUR NRN COUNTIES. WAVES ALONG THE FRONTAL BNDRY WILL
ENHANCE THE CHANCE FOR PCPN THRU THE REMINDER OF THE EXTENDED FCST.
TIMING OF EACH WAVE WILL BE THE DETERMINING FACTOR FOR TIMING OF
PCPN AND THERE IS LITTLE CONFIDENCE WITH THE FAST FLOW FOR PLACEMENT
OF PCPN IN THIS FCST. HAVE WORKED WITH THE 00Z ECMWF TO TRY TO TIME
PCPN INTO THE REGION AS THE ECMWF HAS BEEN FAIRLY CONSISTENT WITH
RUN TO RUN DETAILS. NEXT MAJOR FRONTAL PASSAGE WILL OCCUR TUE BUT
TIMING IS IN QUESTION EVEN HERE WITH THE ECMWF ABOUT 6 HOURS FASTER
THAN THE GFS AND MUCH CLEANER WITH THE PASSAGE AS THE PARENT LOW IS
FARTHER NORTH AND WEST OF THE GFS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 621 PM EST TUE DEC 4 2012
SHOWER ACTIVITY WILL CONTINUE TO INCREASE IN COVERAGE FROM WEST TO
EAST BETWEEN 00-04Z. CONDITIONS WILL DROP TO MVFR WITH THE RAIN...
WITH TEMPORARY IFR CONDITIONS POSSIBLE IN ANY HEAVIER BURSTS OF
RAIN. THE COLD FRONT ASSOCIATED WITH THE PRECIPITATION WILL BRING A
SHIFT IN THE WINDS TO THE NORTHWEST AND EVENTUALLY NORTH AS IT
PASSES. THERE WILL ALSO LIKELY BE AN IFR OR LOWER STRATUS DECK
ASSOCIATED WITH THE COLDER AIR MOVING IN...WHICH IS EXPECTED TO LAST
2 TO 4 HOURS BEFORE CLEARING OUT FROM NORTHWEST TO SOUTHEAST DURING
THE PRE-DAWN HOURS. SKIES WILL CLEAR QUICKLY BY OR SHORTLY AFTER
DAWN AT THE TAF SITES WITH A LIGHT NORTHEAST WIND FORECAST THROUGH
THE DAY ON WEDNESDAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ABE
SHORT TERM...GEOGERIAN
LONG TERM....DUSTY
AVIATION...ABE
AREA FORECAST DISCUSSION
NWS JACKSON KY
823 PM EST TUE DEC 4 2012
.UPDATE...
ISSUED AT 823 PM EST TUE DEC 4 2012
THE COLD FRONT HAS NOW PASSED INTO OUR NORTHWEST COUNTIES HOWEVER
THE SOLID MASS OF RAINFALL THAT WAS ACCOMPANYING THE FRONT EARLIER
HAS WITHERED SUBSTANTIALLY AS IT HAS ENTERED EAST KENTUCKY. THERE IS
STILL ENOUGH PRECIP RIGHT ALONG THE FRONT TO JUSTIFY 100 POPS BUT
FORECAST QPF HAS BEEN REDUCED TO A QUARTER INCH OR LESS FOR MOST
LOCATIONS. TEMPS WILL REMAIN IN THE 60S UNTIL THE FRONT PASSES AND
THEN DROP QUICKLY THROUGH THE 50S. OUR HOURLY TEMP DATA WAS MASSAGED
USING THE RUC13 TIMING BUT THIS WILL NOT ALTER OUR MIN TEMP FORECAST
FOR NOW.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 255 PM EST TUE DEC 4 2012
SURFACE COLD FRONT IS CURRENTLY ALIGNED FROM NORTHWEST OHIO DOWN
THROUGH WESTERN KENTUCKY AND TENNESSEE. THE MAIN BAND OF
PRECIPITATION ASSOCIATED WITH THIS BOUNDARY IS STILL A FEW HOURS
AWAY...WITH MOST OF THIS ACTIVITY WORKING THROUGH IN THE 7 PM TO 12AM
TIME FRAME...AND THEN LINGERING A BIT LONGER IN THE SOUTHEAST AS THE
BOUNDARY SLOWS DOWN ALONG THE TERRAIN. EVERYONE WILL MEASURE OUT OF
THIS...SO SEE NO REASON TO NOT MAINTAIN NEAR 100 POPS. THERE HAS BEEN
SOME LIGHTNING ACTIVITY EMBEDDED WITHIN THE LINE...HOWEVER EXPECT
THESE TO WEAKEN AS IT COMES THROUGH EASTERN KENTUCKY...SO WILL LEAVE
OUT THE MENTION.
HIGH PRESSURE TRAVERSING THE GREAT LAKES AND OHIO VALLEY WILL THEN
PROVIDE DRY WEATHER ACROSS THE AREA FOR WEDNESDAY AND WEDNESDAY
NIGHT. TEMPERATURES WILL BE COOLER THAN WE HAVE BEEN SEEING
LATELY...BUT WILL STILL AVERAGE ABOVE NORMAL...WITH HIGHS GENERALLY
IN THE MID TO UPPER 50S...WITH A FEW LOWER 60S SOUTH ON WEDNESDAY.
LOWS WEDNESDAY NIGHT WILL DROP DOWN TO BELOW 30 IN SOME OF THE MORE
SHELTERED VALLEYS ALONG AND NORTH OF THE MOUNTAIN PARKWAY.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 255 PM EST TUE DEC 4 2012
MODEL PATTERN BEGINS ON THU MORNING WITH A WEAK 50H RIDGE OVER THE
NRN APPALACHIAN MTS AND NEARLY ZONAL FLOW FROM THE PLAINS TO THE
OHIO VALLEY. A WEAK AREA OF LOW PRESSURE OVER THE ERN GULF IS THE
IMPETUS FOR A FEW RETURN FLOW SHOWERS IN THE TENN VALLEY AROUND THE
BACK SIDE OF THE SFC HIGH OVER ERN PA/NY. WEATHER SHOULD REMAIN DRY
AND WARM ALTHOUGH A FEW SPRINKLES COULD BE FOUND LATE THU. BY FRI...
AN AREA OF LOW PRESSURE...ACCOMPANIED BY A LEE SIDE TROUGH...WILL
FORM IN THE SRN PLAINS. THE SFC HIGH WILL HAVE MOVED TO THE ATLANTIC
AND A WARM FRONT WILL BEGIN FORMING FROM OK TO PA. LIFT OVER THE
WARM FRONT FROM THE PREVAILING SOUTHERLY WIND WILL CAUSE A BETTER
CHANCE OF PCPN TO FORM OVER THE OHIO RIVER WITH A GOOD CHANCE OF
RAIN OVER OUR NRN COUNTIES. WAVES ALONG THE FRONTAL BNDRY WILL
ENHANCE THE CHANCE FOR PCPN THRU THE REMINDER OF THE EXTENDED FCST.
TIMING OF EACH WAVE WILL BE THE DETERMINING FACTOR FOR TIMING OF
PCPN AND THERE IS LITTLE CONFIDENCE WITH THE FAST FLOW FOR PLACEMENT
OF PCPN IN THIS FCST. HAVE WORKED WITH THE 00Z ECMWF TO TRY TO TIME
PCPN INTO THE REGION AS THE ECMWF HAS BEEN FAIRLY CONSISTENT WITH
RUN TO RUN DETAILS. NEXT MAJOR FRONTAL PASSAGE WILL OCCUR TUE BUT
TIMING IS IN QUESTION EVEN HERE WITH THE ECMWF ABOUT 6 HOURS FASTER
THAN THE GFS AND MUCH CLEANER WITH THE PASSAGE AS THE PARENT LOW IS
FARTHER NORTH AND WEST OF THE GFS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 621 PM EST TUE DEC 4 2012
SHOWER ACTIVITY WILL CONTINUE TO INCREASE IN COVERAGE FROM WEST TO
EAST BETWEEN 00-04Z. CONDITIONS WILL DROP TO MVFR WITH THE RAIN...
WITH TEMPORARY IFR CONDITIONS POSSIBLE IN ANY HEAVIER BURSTS OF
RAIN. THE COLD FRONT ASSOCIATED WITH THE PRECIPITATION WILL BRING A
SHIFT IN THE WINDS TO THE NORTHWEST AND EVENTUALLY NORTH AS IT
PASSES. THERE WILL ALSO LIKELY BE AN IFR OR LOWER STRATUS DECK
ASSOCIATED WITH THE COLDER AIR MOVING IN...WHICH IS EXPECTED TO LAST
2 TO 4 HOURS BEFORE CLEARING OUT FROM NORTHWEST TO SOUTHEAST DURING
THE PRE-DAWN HOURS. SKIES WILL CLEAR QUICKLY BY OR SHORTLY AFTER
DAWN AT THE TAF SITES WITH A LIGHT NORTHEAST WIND FORECAST THROUGH
THE DAY ON WEDNESDAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ABE
SHORT TERM...GEOGERIAN
LONG TERM....DUSTY
AVIATION...ABE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
650 AM EST MON DEC 3 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 547 AM EST MON DEC 3 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SHORTWAVE TROF EXTENDING
FROM SASKATCHEWAN TO CO. AT THE SFC...ASSOCIATED LOW PRES WAS OVER
FAR NE ND. ALTHOUGH SRLY FLOW AHEAD OF TROF TAPS THE GULF...00Z
RAOBS ACROSS THE PLAINS AND MID/UPPER MISSISSIPPI VALLEY SHOWED
CONSIDERABLE DRY AIR ABOVE SHALLOW SFC BASED MOISTURE. THIS HAS
IMPLICATIONS FOR PCPN FCST DUE TO UNCERTAINTY IN HOW QUICKLY
MOISTURE WILL DEEPEN THRU THE DAY PRIOR TO COLD FRONT ARRIVAL. AT
LEAST FOR THE FIRST PART OF TODAY...SEEMS LIKE ANY PCPN THAT
DEVELOPS WILL BE -DZ DUE TO SHALLOWNESS OF MOISTURE...AND FCST WILL
REFLECT THIS IDEA. MODELS ARE INSISTENT IN DEVELOPING DEEP ENOUGH
MOISTURE FOR SHRA TO BREAK OUT THIS AFTN ALONG/AHEAD OF APPROACHING
COLD FRONT. WITH BEST DEEP LAYER FORCING PASSING TO THE N...NOT
CONVINCED THIS WILL HAPPEN IN TIME BEFORE FRONT CROSSES THE AREA. IF
ANYTHING...IT SEEMS THERE WILL BE SOME DZ AROUND DURING THE DAY AND
THEN MAYBE A SCT/BKN BAND OF SHRA ALONG COLD FRONT. HAVE NUDGED POPS
DOWN A LITTLE...BUT STILL MAINTAINED A BRIEF PERIOD OF LIKELY POPS
OVER THE SCNTRL/E FCST AREA LATE THIS AFTN/EARLY EVENING.
AS ADVECTION OF HIGHER DWPTS CONTINUES TODAY...FOG WILL BE FAIRLY
WIDESPREAD...ESPECIALLY IN THE UPSLOPE AND HIGHER TERRAIN AREAS OF
CNTRL AND WRN UPPER MI. MAY SEE FOG BECOME LOCALLY DENSE THIS
MORNING. WILL MONITOR TRENDS DURING THE EARLY MORNING TO SEE IF
WIDESPREAD 1/4SM OR LESS DEVELOPS TO REQUIRE DENSE FOG ADVY.
ONCE COLD FRONT MOVES ACROSS UPPER MI LATE THIS AFTN AND EVENING...
CAA AND ADVECTION OF MUCH DRIER AIR WILL FINALLY WIPE PESKY STRATUS
AND FOG OUT THE AREA. ANY SHRA WILL END QUICKLY W TO E THIS EVENING
AND IN FACT...SKIES MAY BECOME MOSTLY CLEAR FOR THE OVERNIGHT. LATE
TONIGHT...LAKE AIDED CLOUDS MAY DEVELOP OVER NW UPPER MI IN
W FLOW AS 850MB TEMPS FALL TO -4 TO -8C OVER WRN LAKE SUPERIOR.
SINCE MODELS HAVE BEEN BACKING OFF ON DEGREE OF COOLING...DROPPED
MENTION OF LAKE EFFECT -SHSN ON THE KEWEENAW LATE...ESPECIALLY
CONSIDERING DRYNESS OF AIRMASS THRU THE OVERNIGHT HRS.
MAIN CONCERN TONIGHT WILL BE WINDS OVER THE KEWEENAW. CAA IS STRONG
(THOUGH OVERALL MODEL TREND HAS BEEN A LITTLE WEAKER IN RECENT RUNS)
AND THERE IS SOME HELP FROM THE ISALLOBARIC WIND. 850MB WINDS ARE
PROGGED AT 45-50KT AFTER FROPA...BUT IT APPEARS THAT LOW-LEVEL TEMP
PROFILE WILL NOT QUITE BE UNSTABLE ENOUGH TO FULLY TAP THE PERIOD OF
STRONGER WINDS ALOFT FOLLOWING FROPA. THIS MAY BE PART OF THE REASON
THAT THE MOST RECENT GFS/NAM RUNS HAVE LOWERED 950MB WIND SPEEDS
SLIGHTLY (NOW AROUND 35KT). ANOTHER NEGATIVE IS THAT INITIALLY WINDS
ARE LITTLE MORE WSW THAN THE IDEAL WNW DIRECTION FOR STRONG WINDS ON
THE KEWEENAW. ALSO OF NOTE IS THAT NAM/GFS MOS GUIDANCE FOR KCMX IS
ONLY 19-22KT TONIGHT. WILL PROBABLY SEE SOME GUSTS TO AROUND 45MPH
FOR A TIME ALONG THE WRN SHORE OF THE KEWEENAW DUE TO BETTER
OVERWATER INSTABILITY/COASTAL CONVERGENCE...BUT NOT SURE WIDESPREAD
WIND ADVY CRITERIA WILL BE ACHIEVED. FOR NOW...WILL HOLD OFF ON
ISSUANCE OF WIND ADVY.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 418 AM EST MON DEC 3 2012
BY DAYBREAK TUESDAY MUCH OF THE LOW LEVEL MOISTURE WITH THE INITIAL
COLD FRONT WILL BE OVER LOWER MI...WITH A RIBBON OF DRIER AIR SET UP
ACROSS UPPER MI. THIS WILL BE TEMPORARY AS A REINFORCING COLD FRONT
WRAPS IN DURING THE DAY...AND ANOTHER W-E ORIENTED TROUGH OVER
CENTRAL ONTARIO AT 12Z TUESDAY SLOWLY SINKS ACROSS UPPER MI TUESDAY
NIGHT. 850MB TEMPS WILL FALL FROM A CWA AVERAGE 0C AT DAYBREAK
TUESDAY...TO -6C AT 18Z...AND -12C BY 00Z WEDNESDAY /-15C OFF THE
LATEST NAM RUN/. WILL KEEP THE TREND OF SLOWLY FALLING TEMPS W-E
DURING THE DAY. THIS WILL HELP REMIND FOLKS THAT UNLIKE THE TEMPS WE
WILL HAVE TODAY...THAT IT IS INDEED DECEMBER. HOWEVER...EVEN WITH
HIGH TEMPS 10 TO 18F BELOW TODAY...THEY WILL STILL BE SLIGHTLY ABOVE
NORMAL FOR THIS TIME OF YEAR ACROSS CENTRAL AND E AREAS. ALTHOUGH
TEMPERATURES WILL BE A SHOCK FOR MOST...THE MAIN STORY TUESDAY WILL
BE THE STRONG W WINDS. THE STRONGEST WINDS GUSTING OUT OF THE WNW
BETWEEN 35 AND 45KTS WILL LINGER THROUGH MID MORNING...BEFORE SLOWLY
DIMINISHING DESPITE INCREASED MIXING ABOVE 850MB FROM MID AFTERNOON
ON. THE STRONGEST GUSTS WILL BE REALIZED OVER THE HIGHEST TERRAIN OF
THE KEWEENAW PENINSULA AND W FACING SLOPES NEAR LAKE SUPERIOR.
ALTHOUGH SNOW AMOUNTS WILL LIKELY BE LESS THAN 2 INCHES DURING THE
DAY...THE STRONG WINDS WILL RESULT IN BLOWING SNOW WILL REDUCED
VISIBILITIES. WILL KEEP THE MENTION OF STRONG WINDS AND REDUCED VIS
IN BLOWING SNOW IN THE HWO.
HIGH PRESSURE WILL SLOWLY SLIDE IN TUESDAY NIGHT...AND BE DIRECTLY
OVER HEAD WEDNESDAY. THE RESULT WILL BE A WEAKENING SFC TROUGH AND
DIMINISHING CLOUDS N WINDS OFF LAKE SUPERIOR BECOME LIGHT DURING THE
DAY AND WE BEGIN TO SEE A RETURN OF S WINDS OVER THE W HALF. 850MB
TEMPS WILL RISE SIGNIFICANTLY...FROM THE COOL VALUES AT 00Z
WEDNESDAY TO AN AVERAGE -2C BY 00Z THURSDAY...WITH INVERSION HEIGHTS
FALLING TO AROUND 900MB FOR MUCH OF THE DAY.
THE STRONG WAA WILL CONTINUE WEDNESDAY NIGHT THANKS TO THE INCREASED
PRESSURE GRADIENT BETWEEN THE EXITING STRONG HIGH OVER THE E GREAT
LAKES AND DEEPENING LOW OVER MANITOBA /WITH A SIZABLE TROUGH
EXTENDING THROUGH W TX/. A FEW 50KT WIND BARBS CONTINUE TO BE SHOWN
OVER THE W THIRD OF UPPER MI FROM AROUND 09Z THURSDAY ON. THE STRONG
WINDS WILL LIKELY BE SHORT LIVED...MAXING OUT RIGHT AROUND 12Z OVER
THE W HALF...AND THE E HALF AROUND 18Z. FOR 90-114HRS OUT...THE
03/00Z GFS AND 02/12Z ECMWF WERE IN PRETTY GOOD AGREEMENT ACROSS THE
UPPER GREAT LAKES WITH RESPECT TO THE COLD FRONT OVER W MN AT 12Z
THURSDAY SPLITTING UPPER MI NEARLY IN HALF BY 00Z FRIDAY. ALTHOUGH
THE ECMWF PAINTS AROUND 0.25IN OF LIQUID OVERHEAD THURSDAY INTO
THURSDAY EVENING ALONG AND AHEAD OF THE COLD FRONT...THE GFS HAS A
LIKELY MORE REALISTIC TENTH OF AN INCH OR LESS. GIVEN THE HIGH TEMPS
IN THE MID TO UPPER 30S AND SNOW GROWTH REGION AT OR ABOVE
600MB...PRECIP TYPE IS A CONCERN /ESPECIALLY OFF THE GFS WITH ITS
LESS THAN IMPRESSIVE MOISTURE/. WILL KEEP MIXED PRECIP IN FOR
THURSDAY INTO THURSDAY NIGHT.
COLD HIGH PRESSURE WILL SLOWLY BUILD IN FROM S CENTRAL CANADA AND
THE NORTHERN PLAINS FRIDAY THROUGH SATURDAY...AND BE DIRECTLY
OVERHEAD SUNDAY MORNING. W TO NW WINDS WILL DOMINATE DURING THIS
TIME PERIOD...WITH THE RETURN OF NEAR NORMAL TEMPERATURES /TOPPING
OUT NEAR 30F EACH AFTERNOON/. THE 03/00Z RUN OF THE GFS CONTINUES TO
GET EXCITED ABOUT WAA SWATH OF PRECIP SLIDING IN FROM THE SW AS THE
SFC LOW LINGERS ACROSS THE S PLAINS. RUN TO RUN CONSISTENCY WITHIN
THE GFS HAS SHOWN TO HAVE SOME ISSUES WITH THE PLACEMENT OF THIS
LOW...SO DO NOT HAVE THE HIGHEST CONFIDENCE IN OUR ONGOING FORECAST
FOR SATURDAY NIGHT ON.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 649 AM EST MON DEC 3 2012
WITH UPSLOPE SRLY FLOW AND ABUNDANT LOW LEVEL MOISTURE ACROSS THE
REGION...EXPECT MAINLY LIFR/IFR CIGS TO PERSIST THROUGH MOST OF
TODAY AT KSAW. IT`S QUITE POSSIBLE LIFR CONDITIONS MAY END UP BEING
THE PREVAILING CONDITION AT KSAW UNTIL COLD FROPA THIS EVENING.
DOWNSLOPE NATURE OF SRLY WIND HAS HELPED KIWD/KCMX STAY VFR OVER THE
LAST SEVERAL HRS. WHILE THAT COULD CONTINUE THRU THE MORNING...THE
CONTINUED INFLUX OF HIGHER DWPTS NORTHWARD WOULD ARGUE FOR STRATUS
EVENTUALLY SETTING IN AT KIWD/KCMX. WITH SHARPER DOWNSLOPING AT
KIWD...OPTED FOR JUST A LOW MVFR CIG DEVELOPING THERE WHILE KCMX
SHOULD TREND TO IFR. WHERE WINDS AREN`T GUSTING...LLWS WILL CONTINUE
TODAY. PASSAGE OF A COLD FRONT LATE AFTN/EVENING WILL BRING DRAMATIC
IMPROVEMENT TO VFR AS SUBSTANTIAL DRY/COLD ADVECTION CLEARS
STRATUS/FOG. CONDITIONS ARE FAVORABLE FOR STRONG W WINDS AFTER FROPA
AT KCMX. GUSTS AOA 35KT ARE POSSIBLE THERE TONIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 547 AM EST MON DEC 3 2012
AHEAD OF AN APPROACHING COLD FRONT...S WINDS WILL BE THE RULE TODAY
ACROSS LAKE SUPERIOR. AS IS OFTEN THE CASE WITH S WINDS...THE
STRONGEST WINDS (20-30KT) WILL BE OVER THE E HALF OF LAKE SUPERIOR.
ALTHOUGH WINDS AROUND 1000 FT OFF THE SFC WILL BE IN 40-45KT
RANGE...STABLE TEMP PROFILE WILL KEEP STRONGEST WINDS FROM REACHING
THE LAKE SFC. AT THE HIGHEST OBS PLATFORMS...WILL LIKELY SEE SOME
GALE FORCE GUSTS TO AROUND 35KT OR SO. COLD FRONT WILL CROSS LAKE
SUPERIOR LATE AFTN/EVENING. TIGHT PRES GRADIENT AND INFLUX OF COLDER
AIR THAT WILL ENHANCE MIXING OVER THE WATERS WILL RESULT IN W GALES
OF 35-40KT TONIGHT INTO TUE. APPROACHING HIGH PRES TUE NIGHT/WED WILL
BRING STEADILY DIMINISHING WINDS TO UNDER 15KT DURING THE DAY WED. S
WINDS WILL THEN BE ON THE INCREASE UP TO 30KT WED NIGHT INTO THU AS
PRES GRADIENT SHARPENS BETWEEN DEPARTING HIGH AND APPROACHING COLD
FRONT. EXPECT NW WINDS UP TO 25KT FRI BEHIND THIS NEXT COLD FROPA.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 1 AM TO 7 PM EST TUESDAY FOR LSZ266-267.
GALE WARNING FROM 9 PM EST /8 PM CST/ THIS EVENING TO 7 AM EST
/6 AM CST/ TUESDAY FOR LSZ162.
GALE WARNING FROM 9 PM THIS EVENING TO 4 PM EST TUESDAY FOR
LSZ243-244-264.
GALE WARNING FROM 9 PM THIS EVENING TO 1 PM EST TUESDAY FOR
LSZ242-263.
GALE WARNING FROM 1 AM TO 4 PM EST TUESDAY FOR LSZ245-265.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
547 AM EST MON DEC 3 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 547 AM EST MON DEC 3 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SHORTWAVE TROF EXTENDING
FROM SASKATCHEWAN TO CO. AT THE SFC...ASSOCIATED LOW PRES WAS OVER
FAR NE ND. ALTHOUGH SRLY FLOW AHEAD OF TROF TAPS THE GULF...00Z
RAOBS ACROSS THE PLAINS AND MID/UPPER MISSISSIPPI VALLEY SHOWED
CONSIDERABLE DRY AIR ABOVE SHALLOW SFC BASED MOISTURE. THIS HAS
IMPLICATIONS FOR PCPN FCST DUE TO UNCERTAINTY IN HOW QUICKLY
MOISTURE WILL DEEPEN THRU THE DAY PRIOR TO COLD FRONT ARRIVAL. AT
LEAST FOR THE FIRST PART OF TODAY...SEEMS LIKE ANY PCPN THAT
DEVELOPS WILL BE -DZ DUE TO SHALLOWNESS OF MOISTURE...AND FCST WILL
REFLECT THIS IDEA. MODELS ARE INSISTENT IN DEVELOPING DEEP ENOUGH
MOISTURE FOR SHRA TO BREAK OUT THIS AFTN ALONG/AHEAD OF APPROACHING
COLD FRONT. WITH BEST DEEP LAYER FORCING PASSING TO THE N...NOT
CONVINCED THIS WILL HAPPEN IN TIME BEFORE FRONT CROSSES THE AREA. IF
ANYTHING...IT SEEMS THERE WILL BE SOME DZ AROUND DURING THE DAY AND
THEN MAYBE A SCT/BKN BAND OF SHRA ALONG COLD FRONT. HAVE NUDGED POPS
DOWN A LITTLE...BUT STILL MAINTAINED A BRIEF PERIOD OF LIKELY POPS
OVER THE SCNTRL/E FCST AREA LATE THIS AFTN/EARLY EVENING.
AS ADVECTION OF HIGHER DWPTS CONTINUES TODAY...FOG WILL BE FAIRLY
WIDESPREAD...ESPECIALLY IN THE UPSLOPE AND HIGHER TERRAIN AREAS OF
CNTRL AND WRN UPPER MI. MAY SEE FOG BECOME LOCALLY DENSE THIS
MORNING. WILL MONITOR TRENDS DURING THE EARLY MORNING TO SEE IF
WIDESPREAD 1/4SM OR LESS DEVELOPS TO REQUIRE DENSE FOG ADVY.
ONCE COLD FRONT MOVES ACROSS UPPER MI LATE THIS AFTN AND EVENING...
CAA AND ADVECTION OF MUCH DRIER AIR WILL FINALLY WIPE PESKY STRATUS
AND FOG OUT THE AREA. ANY SHRA WILL END QUICKLY W TO E THIS EVENING
AND IN FACT...SKIES MAY BECOME MOSTLY CLEAR FOR THE OVERNIGHT. LATE
TONIGHT...LAKE AIDED CLOUDS MAY DEVELOP OVER NW UPPER MI IN
W FLOW AS 850MB TEMPS FALL TO -4 TO -8C OVER WRN LAKE SUPERIOR.
SINCE MODELS HAVE BEEN BACKING OFF ON DEGREE OF COOLING...DROPPED
MENTION OF LAKE EFFECT -SHSN ON THE KEWEENAW LATE...ESPECIALLY
CONSIDERING DRYNESS OF AIRMASS THRU THE OVERNIGHT HRS.
MAIN CONCERN TONIGHT WILL BE WINDS OVER THE KEWEENAW. CAA IS STRONG
(THOUGH OVERALL MODEL TREND HAS BEEN A LITTLE WEAKER IN RECENT RUNS)
AND THERE IS SOME HELP FROM THE ISALLOBARIC WIND. 850MB WINDS ARE
PROGGED AT 45-50KT AFTER FROPA...BUT IT APPEARS THAT LOW-LEVEL TEMP
PROFILE WILL NOT QUITE BE UNSTABLE ENOUGH TO FULLY TAP THE PERIOD OF
STRONGER WINDS ALOFT FOLLOWING FROPA. THIS MAY BE PART OF THE REASON
THAT THE MOST RECENT GFS/NAM RUNS HAVE LOWERED 950MB WIND SPEEDS
SLIGHTLY (NOW AROUND 35KT). ANOTHER NEGATIVE IS THAT INITIALLY WINDS
ARE LITTLE MORE WSW THAN THE IDEAL WNW DIRECTION FOR STRONG WINDS ON
THE KEWEENAW. ALSO OF NOTE IS THAT NAM/GFS MOS GUIDANCE FOR KCMX IS
ONLY 19-22KT TONIGHT. WILL PROBABLY SEE SOME GUSTS TO AROUND 45MPH
FOR A TIME ALONG THE WRN SHORE OF THE KEWEENAW DUE TO BETTER
OVERWATER INSTABILITY/COASTAL CONVERGENCE...BUT NOT SURE WIDESPREAD
WIND ADVY CRITERIA WILL BE ACHIEVED. FOR NOW...WILL HOLD OFF ON
ISSUANCE OF WIND ADVY.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 418 AM EST MON DEC 3 2012
BY DAYBREAK TUESDAY MUCH OF THE LOW LEVEL MOISTURE WITH THE INITIAL
COLD FRONT WILL BE OVER LOWER MI...WITH A RIBBON OF DRIER AIR SET UP
ACROSS UPPER MI. THIS WILL BE TEMPORARY AS A REINFORCING COLD FRONT
WRAPS IN DURING THE DAY...AND ANOTHER W-E ORIENTED TROUGH OVER
CENTRAL ONTARIO AT 12Z TUESDAY SLOWLY SINKS ACROSS UPPER MI TUESDAY
NIGHT. 850MB TEMPS WILL FALL FROM A CWA AVERAGE 0C AT DAYBREAK
TUESDAY...TO -6C AT 18Z...AND -12C BY 00Z WEDNESDAY /-15C OFF THE
LATEST NAM RUN/. WILL KEEP THE TREND OF SLOWLY FALLING TEMPS W-E
DURING THE DAY. THIS WILL HELP REMIND FOLKS THAT UNLIKE THE TEMPS WE
WILL HAVE TODAY...THAT IT IS INDEED DECEMBER. HOWEVER...EVEN WITH
HIGH TEMPS 10 TO 18F BELOW TODAY...THEY WILL STILL BE SLIGHTLY ABOVE
NORMAL FOR THIS TIME OF YEAR ACROSS CENTRAL AND E AREAS. ALTHOUGH
TEMPERATURES WILL BE A SHOCK FOR MOST...THE MAIN STORY TUESDAY WILL
BE THE STRONG W WINDS. THE STRONGEST WINDS GUSTING OUT OF THE WNW
BETWEEN 35 AND 45KTS WILL LINGER THROUGH MID MORNING...BEFORE SLOWLY
DIMINISHING DESPITE INCREASED MIXING ABOVE 850MB FROM MID AFTERNOON
ON. THE STRONGEST GUSTS WILL BE REALIZED OVER THE HIGHEST TERRAIN OF
THE KEWEENAW PENINSULA AND W FACING SLOPES NEAR LAKE SUPERIOR.
ALTHOUGH SNOW AMOUNTS WILL LIKELY BE LESS THAN 2 INCHES DURING THE
DAY...THE STRONG WINDS WILL RESULT IN BLOWING SNOW WILL REDUCED
VISIBILITIES. WILL KEEP THE MENTION OF STRONG WINDS AND REDUCED VIS
IN BLOWING SNOW IN THE HWO.
HIGH PRESSURE WILL SLOWLY SLIDE IN TUESDAY NIGHT...AND BE DIRECTLY
OVER HEAD WEDNESDAY. THE RESULT WILL BE A WEAKENING SFC TROUGH AND
DIMINISHING CLOUDS N WINDS OFF LAKE SUPERIOR BECOME LIGHT DURING THE
DAY AND WE BEGIN TO SEE A RETURN OF S WINDS OVER THE W HALF. 850MB
TEMPS WILL RISE SIGNIFICANTLY...FROM THE COOL VALUES AT 00Z
WEDNESDAY TO AN AVERAGE -2C BY 00Z THURSDAY...WITH INVERSION HEIGHTS
FALLING TO AROUND 900MB FOR MUCH OF THE DAY.
THE STRONG WAA WILL CONTINUE WEDNESDAY NIGHT THANKS TO THE INCREASED
PRESSURE GRADIENT BETWEEN THE EXITING STRONG HIGH OVER THE E GREAT
LAKES AND DEEPENING LOW OVER MANITOBA /WITH A SIZABLE TROUGH
EXTENDING THROUGH W TX/. A FEW 50KT WIND BARBS CONTINUE TO BE SHOWN
OVER THE W THIRD OF UPPER MI FROM AROUND 09Z THURSDAY ON. THE STRONG
WINDS WILL LIKELY BE SHORT LIVED...MAXING OUT RIGHT AROUND 12Z OVER
THE W HALF...AND THE E HALF AROUND 18Z. FOR 90-114HRS OUT...THE
03/00Z GFS AND 02/12Z ECMWF WERE IN PRETTY GOOD AGREEMENT ACROSS THE
UPPER GREAT LAKES WITH RESPECT TO THE COLD FRONT OVER W MN AT 12Z
THURSDAY SPLITTING UPPER MI NEARLY IN HALF BY 00Z FRIDAY. ALTHOUGH
THE ECMWF PAINTS AROUND 0.25IN OF LIQUID OVERHEAD THURSDAY INTO
THURSDAY EVENING ALONG AND AHEAD OF THE COLD FRONT...THE GFS HAS A
LIKELY MORE REALISTIC TENTH OF AN INCH OR LESS. GIVEN THE HIGH TEMPS
IN THE MID TO UPPER 30S AND SNOW GROWTH REGION AT OR ABOVE
600MB...PRECIP TYPE IS A CONCERN /ESPECIALLY OFF THE GFS WITH ITS
LESS THAN IMPRESSIVE MOISTURE/. WILL KEEP MIXED PRECIP IN FOR
THURSDAY INTO THURSDAY NIGHT.
COLD HIGH PRESSURE WILL SLOWLY BUILD IN FROM S CENTRAL CANADA AND
THE NORTHERN PLAINS FRIDAY THROUGH SATURDAY...AND BE DIRECTLY
OVERHEAD SUNDAY MORNING. W TO NW WINDS WILL DOMINATE DURING THIS
TIME PERIOD...WITH THE RETURN OF NEAR NORMAL TEMPERATURES /TOPPING
OUT NEAR 30F EACH AFTERNOON/. THE 03/00Z RUN OF THE GFS CONTINUES TO
GET EXCITED ABOUT WAA SWATH OF PRECIP SLIDING IN FROM THE SW AS THE
SFC LOW LINGERS ACROSS THE S PLAINS. RUN TO RUN CONSISTENCY WITHIN
THE GFS HAS SHOWN TO HAVE SOME ISSUES WITH THE PLACEMENT OF THIS
LOW...SO DO NOT HAVE THE HIGHEST CONFIDENCE IN OUR ONGOING FORECAST
FOR SATURDAY NIGHT ON.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1206 AM EST MON DEC 3 2012
WITH SRLY FLOW AND PLENTIFUL LOW LEVEL MOISTURE ACROSS THE
REGION...EXPECT MAINLY IFR CIGS TO PERSIST THROUGH MOST OF TODAY.
HOWEVER...WITH DOWNSLOPE FLOW AND STRONGER MIXING DEVELOPING WITH A
STRENGTHENING LOW LEVEL JET...THE LOWER CIGS MAY LIFT FOR A TIME AT
IWD. SINCE CONFIDENCE IN LENGTH OF CLEARING AT IWD WAS LOW...KEPT
FCST WITH PREDOMINANT IFR. THE FOG MAY ALSO BECOME THICKER...
ESPECIALLY AT SAW...BUT THE LOW LEVEL MIXING SHOULD BE STRONG ENOUGH
TO MINIMIZE DENSE FOG CHANCES OR POTENTIAL FOR VLIFR CONDITIONS. AS
COLD FRONT MOVES THROUGH LATE AFTERNOON AND EVENING...SUBSTANTIAL
DRY/COLD ADVECTION WITH INCREASING INSTABILITY WILL BRING QUICK
IMPROVMENT TO AT LEAST MVFR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 547 AM EST MON DEC 3 2012
AHEAD OF AN APPROACHING COLD FRONT...S WINDS WILL BE THE RULE TODAY
ACROSS LAKE SUPERIOR. AS IS OFTEN THE CASE WITH S WINDS...THE
STRONGEST WINDS (20-30KT) WILL BE OVER THE E HALF OF LAKE SUPERIOR.
ALTHOUGH WINDS AROUND 1000 FT OFF THE SFC WILL BE IN 40-45KT
RANGE...STABLE TEMP PROFILE WILL KEEP STRONGEST WINDS FROM REACHING
THE LAKE SFC. AT THE HIGHEST OBS PLATFORMS...WILL LIKELY SEE SOME
GALE FORCE GUSTS TO AROUND 35KT OR SO. COLD FRONT WILL CROSS LAKE
SUPERIOR LATE AFTN/EVENING. TIGHT PRES GRADIENT AND INFLUX OF COLDER
AIR THAT WILL ENHANCE MIXING OVER THE WATERS WILL RESULT IN W GALES
OF 35-40KT TONIGHT INTO TUE. APPROACHING HIGH PRES TUE NIGHT/WED WILL
BRING STEADILY DIMINISHING WINDS TO UNDER 15KT DURING THE DAY WED. S
WINDS WILL THEN BE ON THE INCREASE UP TO 30KT WED NIGHT INTO THU AS
PRES GRADIENT SHARPENS BETWEEN DEPARTING HIGH AND APPROACHING COLD
FRONT. EXPECT NW WINDS UP TO 25KT FRI BEHIND THIS NEXT COLD FROPA.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 1 AM TO 7 PM EST TUESDAY FOR LSZ266-267.
GALE WARNING FROM 9 PM EST /8 PM CST/ THIS EVENING TO 7 AM EST
/6 AM CST/ TUESDAY FOR LSZ162.
GALE WARNING FROM 9 PM THIS EVENING TO 4 PM EST TUESDAY FOR
LSZ243-244-264.
GALE WARNING FROM 9 PM THIS EVENING TO 1 PM EST TUESDAY FOR
LSZ242-263.
GALE WARNING FROM 1 AM TO 4 PM EST TUESDAY FOR LSZ245-265.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...KF
AVIATION...JLB
MARINE...ROLFSON
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
857 PM MST TUE DEC 4 2012
.SHORT TERM...VALID FOR WED AND THU...
JUST SOME SMALL ADJUSTMENTS FOR THE UPDATE THIS EVENING.
MOISTURE...MAINLY MID AND HIGH LEVEL...WAS SEEN STREAMING INTO THE
AREA THIS EVENING ON SATELLITE LOOPS AND RADAR. MOISTURE FEED WAS
AIDED BY PACIFIC JET ENERGY. BOTH WRF AND GFS SHOWED MOISTURE
INCREASING OVER THE WESTERN MOUNTAINS OVERNIGHT. ADJUSTED POPS TO
REFLECT HIGH CHANCES OVER W FACING SLOPES OF THE
BEARTOOTHS/ABSAROKAS THROUGH 06Z AND RAISED POPS OVER THE CRAZY
MOUNTAINS AS WELL. AIRMASS WAS NOT VERY COLD...SO SNOW AMOUNTS
WILL BE LIMITED. BOTH MODELS CONTINUED TO SHOW SOME MOISTURE
MOVING THROUGH THE N CENTRAL ZONES OVERNIGHT AS WEAK SHORTWAVES
AND WARM ADVECTION MOVE THROUGH THE AREA. CONTINUED SLIGHT CHANCE
POPS IN THIS REGION. RAP BUFKIT KMLS SOUNDING SUPPORTED RAIN OR
SNOW AS THE PRECIPITATION TYPE SO WILL REMOVE THE MENTION OF
FREEZING DRIZZLE.
TIGHT N TO S ORIENTED PRESSURE GRADIENT AND STABLE LOW LAYER WAS
SUPPORTING ADVISORY STRENGTH GAP FLOW WINDS THIS EVENING IN THE
KLVM AREA. WINDS WERE OSCILLATING BETWEEN JUST BELOW AND JUST
ABOVE ADVISORY SPEEDS. CALL TO THE STILLWATER MINE AT 340Z
REVEALED WINDS JUST UNDER ADVISORY SPEEDS. WINDS WILL LIKELY DROP
TO BELOW ADVISORY CRITERIA LATE WED MORNING FOR THE GAP AREAS AS
INSTABILITY INCREASES OVER THE AREA AHEAD OF AN APPROACHING COLD
FRONT. WILL MAKE NO CHANGES TO THE ADVISORY. THE FRONT WILL BRING
A SLIGHT CHANCE OF PRECIPITATION TO MUCH OF THE AREA ON WED. LOW
PRESSURE WILL MOVE THROUGH WY THU INTO THU NIGHT AND COMBINE WITH
LIFT FROM A STRONG PACIFIC JET TO BRING A RAIN AND SNOW MIX TO THE
AREA ON THU WITH SNOW THU NIGHT. BEST CHANCES FOR SOME SNOW
ACCUMULATION WILL BE ACROSS THE SOUTHERN HALF OF THE AREA THU
NIGHT. ARTHUR
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
MEDIUM RANGE GUIDANCE IN DECENT AGREEMENT AGAIN THROUGH MUCH OF
THE EXTENDED...THERE ARE JUST SOME DIFFERENCES IN TIMING AND
STRENGTH OF FEATURES SUCH AS THE UPPER LEVEL TROUGH THAT WILL BE
IMPACTING THE REGION FRIDAY THROUGH SUNDAY. LEANED TOWARDS A
CONSALL/BCCONSALL BLEND FOR EXTENDED RANGE TEMPS...WHICH LOOK TO
GENERALLY BE IN THE 20S AND 30S FOR HIGHS.
ON FRIDAY...WEAK SHORTWAVE ENERGY IN NW FLOW ALOFT MOVES THROUGH
THE REGION...BRINGING SOME LIGHT SNOW OR SNOW SHOWERS TO THE
WESTERN MOUNTAINS AND FOOTHILLS. STRONGER SHORTWAVE ENERGY...PACIFIC
MOISTURE AND UPPER LEVEL JUST SUPPORT/DIVERGENCE HELP TO AMPLIFY
AN UPPER LEVEL TROUGH ACROSS THE NORTHERN/CENTRAL ROCKIES FRIDAY
NIGHT THROUGH EARLY SUNDAY...ALLOWING A DISORGANIZED STORM
SYSTEM...WITH A COUPLE OF CIRCULATIONS AT THE SURFACE...TO DROP
SOUTHEASTWARD ACROSS THE REGION. WHILE COLDER TEMPS LOOK CERTAIN
FOR SATURDAY INTO SUNDAY...SNOW POTENTIAL CONTINUE TO REMAIN MORE
UNCERTAIN...ESPECIALLY ACROSS THE PLAINS. AM MORE CONFIDENT THAT
THE MOUNTAINS WILL AGAIN PICK UP SOME SNOW...THUS BUMPED UP POPS
IN THE HIGHER ELEVATIONS AND ACROSS THE WESTERN AND SOUTHERN
FOOTHILLS. MAY ALSO NEED TO WATCH FAVORED UPSLOPE REGIONS ACROSS
SOUTHEASTERN MONTANA AS SOMEWHAT MOIST NW FLOW ON THE BACKSIDE OF
THE SYSTEM MAY INCREASE THE POTENTIAL FOR SNOW.
THE SYSTEM MOVES OUT OF THE REGION SUNDAY AS AN UPPER LEVEL RIDGE
BUILDS IN AHEAD OF THE NEXT SHORTWAVE/SURFACE COLD FRONT
COMBINATION. THE PRESSURE GRADIENT LOOKS TO TIGHTEN SUNDAY NIGHT
ACROSS THE WEST IN ADVANCE OF THE NEXT SYSTEM...SO A PERIOD OF
STRONGER WINDS IS POSSIBLE FOR PLACES LIKE LIVINGSTON AND BIG
TIMBER...AND ALONG THE BEARTOOTH/ABSAROKA FOOTHILLS. PRECIP
POTENTIAL LOOKS TO INCREASE AGAIN...ESPECIALLY FOR THE MOUNTAINS
MONDAY AS THE SHORTWAVE/COLD FRONT COMBO MOVES THROUGH THE REGION
WITH SOME PACIFIC MOISTURE. THE GFS IS MORE AGGRESSIVE WITH THIS
SYSTEM THAN THE ECMWF. EXACTLY HOW POTENT THIS SYSTEM IS REMAINS
TO BE SEEN...BUT DID INCREASE POPS OVER THE MOUNTAINS/FOOTHILLS
JUST A BIT. THERE ARE INDICATIONS THAT ANOTHER PERIOD OF STRONGER
WINDS MAY OCCUR ACROSS THE WEST BY LATE TUESDAY. WILL NEED TO
WATCH THAT. STC
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. A SERIES OF WEAK
DISTURBANCES...AND A COLD FRONT THAT WILL MOVE THROUGH THE AREA
WEDNESDAY AFTERNOON...MAY PRODUCE WIDELY SCATTERED RAIN AND SNOW
SHOWERS TONIGHT INTO TOMORROW. OCCASIONAL MOUNTAIN OBSCURATIONS
ARE ALSO LIKELY. GUSTY WINDS WILL CONTINUE TO PLAGUE AREAS IN AND
AROUND LIVINGSTON WITH GUSTS GREATER THAN 40 KTS POSSIBLE THROUGH
MID DAY WEDNESDAY. BEHIND THE FRONT WEDNESDAY AFTERNOON...WINDS
WILL BECOME NW AT ALL TAF SITES EXCEPT KLVM. DLB/STC
&&
.PRELIMINARY POINT TEMP/POPS...
WED THU FRI SAT SUN MON TUE
-----------------------------------------------------------
BIL 040/057 028/036 024/033 026/029 011/022 016/032 021/037
02/W 24/O 63/S 23/S 31/B 12/S 21/B
LVM 045/052 026/036 019/033 026/026 008/021 011/031 015/033
12/W 26/O 63/S 44/S 32/S 33/S 32/S
HDN 031/057 029/037 025/034 020/029 009/022 013/030 017/035
02/W 22/O 63/S 23/S 31/B 12/S 21/B
MLS 031/055 025/037 021/031 019/029 011/019 012/029 019/033
22/W 22/O 43/S 24/S 31/B 12/S 11/B
4BQ 031/057 027/038 021/033 019/029 011/021 010/028 017/032
01/B 22/O 64/S 24/S 31/B 12/S 11/B
BHK 026/055 022/035 020/031 017/028 011/018 011/026 017/030
01/E 21/B 32/S 24/S 31/B 12/S 11/E
SHR 029/056 027/036 019/032 015/028 007/018 007/024 011/033
01/B 23/O 63/S 23/S 31/B 22/S 21/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY IN EFFECT UNTIL 6 PM MST WEDNESDAY FOR ZONES
65-66.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1222 PM CST MON DEC 3 2012
.UPDATE...LOW LEVEL PRESSURE RISES AND THE RESULTANT INCREASING
LOW LEVEL PRESSURE GRADIENT CONTINUES TO PROMOTE STRONG WINDS
ACROSS THE AREA. SUSTAINED WINDS ACROSS THE AREA HAVE GENERALLY
BEEN IN THE 20-25KT RANGE SINCE 17Z. THAT BEING SAID...A FEW
SITES...PRIMARILY ALONG THE I-80 CORRIDOR...HAVE PERIODICALLY
CREPT UP INTO THE 26-30KT RANGE. THESE REPORTS HAVE BEEN FLEETING
HOWEVER AND AS OF 1815Z ONLY ONE SITE ACROSS THE CWA IS HITTING
WIND ADVISORY CRITERIA. SHORT TERM GUIDANCE PER THE RAP CONTINUES
TO SUGGEST THE STRONGEST LOW LEVEL PRESSURE GRADIENT WILL CONTINUE
MOVING EAST THROUGH THE NEXT FEW HOURS...THUS RESULTING IN A
DECREASING LOW LEVEL WIND FIELD THROUGH THIS AFTERNOON. THIS
GUIDANCE IS SUPPORTED BY OBSERVATION SITES UPSTREAM...WHICH ARE
GENERALLY SUSTAINED IN THE 15-20KT RANGE. ALL OF THIS INFORMATION
WOULD SUGGEST THE LOW LEVEL WIND FIELD ACROSS OUR CWA WILL DISPLAY
A MARKED DECREASE IN INTENSITY THROUGH THE NEXT 2-3 HOURS...WITH
THE STRONGEST WINDS LIKELY BEING OBSERVED NOW IF THEY HAVENT
ALREADY. GIVEN ALL THIS...WILL CONTINUE TO HOLD OFF FROM ANY
HEADLINE ISSUANCE AND CONTINUE TO MONITOR.
WENT AHEAD AND TWEAKED HOURLY SKY...TEMPERATURE AND DEWPOINT GRIDS
TO BETTER REFLECT CURRENT CONDITIONS. THESE CHANGES WERE VERY
MINOR HOWEVER AS THE OVERALL FORECAST REMAINS IN GREAT SHAPE AT
THIS TIME.
&&
.PREV DISCUSSION... /ISSUED 1112 AM CST MON DEC 3 2012/
AVIATION...18Z KGRI TAF. VFR CONDITIONS TO CONTINUE THROUGH THE
NEXT 24 HOURS. THE SURFACE WIND WILL REMAIN STRONG THROUGH
23Z...SUSTAINED AT 25KTS AND GUSTING AROUND 35KTS. THE SURFACE
WIND WILL THEN WEAKEN SIGNIFICANTLY AFTER 23Z. A FEW HIGH CLOUDS
WILL BE POSSIBLE DURING THE TAF PERIOD AND VISIBILITY RESTRICTIONS
ARE NOT EXPECTED THROUGH THE NEXT 24 HOURS.
PREV DISCUSSION... /ISSUED 954 AM CST MON DEC 3 2012/
UPDATE...MORNING UPPER AIR ANALYSIS INDICATES AN UPPER LEVEL
TROUGH EXTENDING FROM SOUTH CENTRAL CANADA INTO THE NORTHERN HIGH
PLAINS. RIDGING EXISTS OVER THE EASTERN HALF OF THE CONUS WITH
QUASI-ZONAL OVER MUCH OF THE WEST. MID AND UPPER LEVEL JET ENERGY
EXTENDS FROM NORTHERN CALIFORNIA...EAST/NORTHEAST INTO THE
NORTHERN PLAINS AND SOUTH CENTRAL CANADA...AND THEN EAST/SOUTHEAST
INTO SOUTHEASTERN CANADA AND THE NORTHEASTERN CONUS. MUCH OF THIS
JET ENERGY REMAINS WEST/NORTHWEST OF OUR AREA AND AS A
RESULT...TROPOSPHERIC FLOW OVER OUR AREA REMAINS FAIRLY
WEAK...MAXING OUT AT AROUND 90KTS NEAR 150MB PER 12Z SOUNDING DATA
FROM KLBF. WATER VAPOR IMAGERY INDICATES A MID LEVEL LOW OVER
SOUTHERN SASKATCHEWAN...EMBEDDED WITHIN THE UPPER LEVEL LONGWAVE
TROUGH. INCREASED VALUES OF MID LEVEL MOISTURE ARE ALSO NOTED
AHEAD OF THE MID LEVEL LOW AND UPPER LEVEL LONGWAVE
TROUGH...EXTENDING FROM THE CENTRAL PLAINS NORTHEAST INTO SOUTH
CENTRAL CANADA. AT THE SURFACE AN AREA OF LOW PRESSURE IS NOTED
OVER SOUTHERN MANITOBA...WITH AN ASSOCIATED COLD FRONT EXTENDING
SOUTH/SOUTHWEST FORM THE LOW. AS OF 14Z THIS FRONT WAS NOTED
EXTENDING FROM NEAR KOFK...TO NEAR KAUH...TO NEAR KHYS. THE LOW
LEVEL WIND FIELD REMAINS LIGHT AND VARIABLE FOR LOCATIONS ACROSS
OUR CWA STILL AHEAD OF THE LOW LEVEL BAROCLINIC ZONE. FOR
LOCATIONS FARTHER WEST/NORTHWEST HOWEVER...THE LOW LEVEL WIND
FIELD HAS TURNED WEST/NORTHWEST AND IS INCREASING IN INTENSITY.
POOLING OF LOW LEVEL MOISTURE...WORKING IN CONCERT WITH THE LIGHT
LOW LEVEL WIND FIELD...PROMOTED FOG ACROSS EASTERN PORTIONS OF THE
CWA EARLIER THIS MORNING. WITH FROPA BEING COMPLETE ACROSS MUCH OF
THE CWA HOWEVER...A MUCH DRIER LOW LEVEL AIRMASS AND A STRONG LOW
LEVEL WIND FIELD IS WORKING TO DIMINISH THE FOG. THE VISIBILITY
HAS CLIMBED WELL ABOVE 1/4SM FOR MOST LOCATIONS ACROSS THE
CWA...WITH THE ONLY EXCEPTION BEING KK61 AS OF 15Z...BUT THIS
RESTRICTION IN VISIBILITY IS NOT EXPECTED TO PERSIST FOR MORE THAN
AN HOUR AS THE LOW LEVEL BAROCLINIC ZONE CLEARS THE AREA. THE
DENSE FOG ADVISORY WAS ALLOWED TO EXPIRE AT 9 AM AS A RESULT.
LOW LEVEL PRESSURE RISES POST-FROPA ARE WORKING TO INCREASE THE
LOW LEVEL PRESSURE GRADIENT ACROSS WESTERN NEBRASKA AT THIS
HOUR...WITH STRONG NORTHWEST WINDS ALREADY NOTED AT KLBF AND KBBW
AS OF 15Z. THIS INCREASING LOW LEVEL PRESSURE GRADIENT...AND
RESULTANT STRONGER WINDS...ARE EXPECTED TO OVERTAKE OUR CWA
THROUGH THE REST OF THIS MORNING. IN ADDITION TO THE INCREASING
LOW LEVEL PRESSURE GRADIENT...AFTERNOON BOUNDARY LAYER MIXING TO
AROUND 800MB SHOULD TAP INTO WINDS OF AROUND 30KTS. GIVEN ALL
THIS...WINDY CONDITIONS WILL CERTAINLY BE OBSERVED ACROSS THE
ENTIRE CWA TODAY. MAV GUIDANCE DOES SUGGEST KEAR...KGRI AND KHSI
WILL HIT WIND ADVISORY CRITERIA FOR A TIME AROUND 18Z...HOWEVER
THIS IS EXPECTED TO BE VERY SHORT-LIVED AS THE STRONGEST LOW LEVEL
PRESSURE GRADIENT QUICKLY PUSHES OFF TO THE EAST. SEEING AS HOW
ANY WINDS THAT ARE STRONG ENOUGH TO MEET WIND ADVISORY CRITERIA
SHOULD BE VERY BRIEF...WILL HOLD OFF FROM WIND ADVISORY ISSUANCE
AT THIS TIME AND CONTINUE TO MONITOR.
PREV DISCUSSION... /ISSUED 618 AM CST MON DEC 3 2012/
UPDATE...VISIBILITIES HAVE DROPPED TO ONE QUARTER MILE IN FOG
ACROSS OUR EASTERN ZONES ALONG TROUGH AXIS/LIGHT WINDS AHEAD OF
FRONT. DUE TO THE LOW VISIBILITIES HAVE ISSUED A DENSE FOG
ADVISORY FOR A FEW HOURS THIS MORNING UNTIL FRONT MOVES THROUGH
AND SCOURS THE LLVL MOISTURE AND MIXING INCREASES.
PREV DISCUSSION... /ISSUED 355 AM CST MON DEC 3 2012/
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT. PRIMARY FORECAST
CONCERNS LIE WITH TEMPERATURES AND WINDS.
QUIET CONDITIONS ARE IN PLACE ACROSS THE CWA EARLY THIS
MORNING...WITH UPPER AIR PROFILER AND SATELLITE DATA SHOWING
SOUTHWESTERLY FLOW OVER THE REGION AHEAD OF A TROUGH GRADUALLY
MAKING ITS WAY OUT OF THE ROCKIES AND ONTO THE PLAINS...ASSOCIATED
WITH AN AREA OF LOW PRESSURE OVER SRN SASKATCHEWAN. AT THE
SURFACE...CONTINUING TO SEE LIGHT SOUTHERLY FLOW ACROSS THE
CWA...WITH THE MAIN TROUGH AXIS AND COLD FRONT STILL OFF TO THE
WEST OF THE CWA. SKIES TO THIS POINT HAD BEEN MOSTLY CLEAR...BUT
EXPANSIVE AREA OF MID/UPPER LEVEL CLOUDS ARE NOW MAKING THEIR WAY
INTO WRN PORTIONS OF THE CWA.
LOOKING AT THE REST OF TODAY...THE FORECAST REMAINS DRY WITH
MODELS IN GOOD AGREEMENT KEEPING BETTER PRECIPITATION CHANCES N/NW
OF THE CWA. WILL KEEP THE MENTION OF SOME FOG IN FOR JUST THIS
MORNING...IN THE SAME AREA AS INHERITED /ERN TIER/...CONTINUES TO
BE SOME MODELS DEPICTING SOME DEVELOPMENT JUST AHEAD OF THE SFC
FRONT. OTHERWISE...TIMING OF THE FRONT BRINGS THE IT THROUGH THE
CWA BY EARLY AFTERNOON...WITH GUSTY NORTHWEST WINDS DEVELOPING
BEHIND WITH PRESSURE RISES AND FORECAST SOUNDINGS SHOWING MIXING
UPWARDS OF 8-850MB. COULD BE A BRIEF PERIOD...ESP LATER THIS
MORNING/NEAR MIDDAY WITH THE INITIAL PASSAGE OF THE FRONT...WHERE
SOME LOCATIONS FLIRT WITH WIND ADV CRITERIA...BUT WILL BE HOLDING
OFF ON ANY HEADLINE. DURING THE AFTERNOON HOURS...THE SUSTAINED
SPEEDS SHOULD TAPER OFF A BIT...BUT STILL WILL BE PLENTY GUSTY. BY
EVENING...SFC HIGH PRESSURE SETTLING IN FROM THE WEST SHOULD KNOCK
SPEEDS DOESNT CLOSER TO 10 MPH.
THE AREA OF CLOUD COVER MOVING IN THIS MORNING LOOKS TO KEEP SKIES
PARTLY/MOSTLY CLOUDY...MAINLY DURING THE FIRST HALF OF THE
DAY...BUT AM EXPECTING MORE SUN DURING THE AFTERNOON /ESP IN
CNTRL/WRN AREAS/. MAIN CHANGE MADE TO THE FORECAST FOR TODAY WAS
TO TREND BACK AFTERNOON DEWPOINTS...MAINLY ACROSS THE WRN HALF OF
THE CWA. FELT WITH THE DECENT MIXING BEHIND THE FRONT AND DRIER
AIR BUILDING IN...GOING CLOSER TO GUIDANCE WAS THE WAY TO GO. DID
NOT MAKE ANY NOTABLE CHANGES TO THE HIGHS...WHICH STILL LOOK TO
TOP OUT IN THE MID 50S TO NEAR 60S. WITH THE DECREASE IN AFTN
DEWPOINTS AND FORECAST HIGHS...THIS DID RESULT IN A DECREASE IN RH
VALUES...WITH AREAS GENERALLY ALONG/WEST OF A ODX/EAR/SMITH CENTER
KS LINE DROPPING INTO THE MID 20 PERCENT RANGE. CONDITIONS
EXPECTED TO REMAIN BELOW CRITICAL FIRE LEVELS...SO NO
HEADLINE...BUT WILL PUT AN ELEVATED MENTION IN THE HWO.
AS WE GET INTO TUESDAY AND WEDNESDAY...THE FORECAST REMAINS
PRECIPITATION FREE...MODELS ARE IN PRETTY GOOD AGREEMENT SHOWING
SLIGHTLY NORTHWESTERLY/ZONAL FLOW IN PLACE IN THE UPPER
LEVELS...WITH TODAYS TROUGH HAVING SHIFTED OFF TOWARD THE EAST
COAST AND VERY WEAK/BROAD RIDGING TO THE WEST. LOOKING AT THE
SURFACE PATTERN ON TUESDAY...EXPECTING TO SEE LIGHTER WINDS
CONTINUE WITH WEAKER HIGH PRESSURE IN PLACE OVER THE PLAINS...WITH
A PRIMARILY WESTERLY COMPONENT. INTO WEDNESDAY...AS ANOTHER UPPER
LEVEL TROUGH SETS UP TO THE WEST OF THE REGION...A SFC TROUGH
DEVELOPS OVER THE HIGH PLAINS...RESULTING IN A RETURN TO SOUTHERLY
WINDS ACROSS THE CWA. WEDNESDAY LOOKS TO BE ANOTHER BREEZY
DAY...WITH A TIGHTENING SFC PRESSURE GRADIENT ACROSS THE CENTRAL
PLAINS...SUSTAINED SPEEDS OF 15 TO 25 MPH WITH GUSTS OVER 30 MPH
ARE EXPECTED.
AS FAR AS TEMPERATURES GO THROUGH WEDNESDAY...DONT SEE A
SIGNIFICANT CHANGE EITHER WAY IN THE AIRMASS IN PLACE...AND
TUESDAYS HIGHS LOOK TO BE FAIRLY SIMILAR TO TODAY...IN THE MID
50S/NEAR 60. EXPECTING TO SEE A SLIGHT BUMP UP GETTING INTO
WEDNESDAY...THERE IS AN INCREASE IN TEMPS ALOFT...AND ALONG WITH
THE MORE SOLID SOUTHERLY FLOW...HIGHS IN THE UPPER 50S/LOWER 60S
ARE EXPECTED. ALSO WILL SEE THAT INCREASING TREND IN OVERNIGHT LOW
TEMPERATURES...TONIGHT WITH LIGHTER WINDS AND SFC HIGH PRESSURE IN
THE REGION...LOWS LOOK TO FALL INTO THE 20S. TUESDAY NIGHT AND
WEDNESDAY NIGHT...THE MORE SOUTHERLY WINDS ARE IN PLACE AND
SLIGHTLY WARMER AIR...SHOULD SEE LOWS IN THE UPPER 20S/LOW 30S
TUESDAY NIGHT AND MID/UPPER 30S WEDNESDAY NIGHT.
LONG TERM...THURSDAY THROUGH SUNDAY. THE WEATHER PATTERN UNDERGOES
CHANGES DURING THE LONG TERM PERIODS...ESPECIALLY HEADING INTO
NEXT WEEKEND. A TROUGH OF LOW PRESSURE TRANSLATES ACROSS CANADA ON
THURSDAY BRINGING AN ATTENDED COLD FRONTAL BOUNDARY ACROSS THE
CENTRAL PLAINS. IN PRESENCE OF MID LEVEL FRONTOGENESIS AND
DIVERGENCE ALOFT IN LFQ OF JET STREAK CROSSING THE SOUTHERN
PLAINS...SOME CHC FOR RAIN IS POSSIBLE. COOLER AIR FILTERS SOUTH
INTO OUR REGION BEHIND THE FRONT THURSDAY AND A GENERAL DOWNWARD
TREND IN TEMPS IS EXPECTED DURING LATTER PART OF THE WORKWEEK AND
ALSO HEADING INTO THE WEEKEND. COLD AIR BOTTLED UP IN CANADA WILL
MAKE A GRADUAL PROGRESSION SOUTH AS SHORTWAVE ENERGY TRANSLATES
ACROSS CANADA AND THE NORTHERN PLAINS. TEMPS SHOULD RETURN CLOSER
TO SEASONAL NORMALS BY FRIDAY/SATURDAY.
EXTENDED MODELS ADVERTISE A TROUGH TO IMPACT THE PLAINS NEXT
WEEKEND BUT DIFFER ON STRENGTH/TIMING OF SYSTEM. THE ECMWF IS MORE
PROGRESSIVE WITH WAVE AND BRINGS IN AN ARCTIC COLD FRONT ON SUNDAY
WITH POTENTIAL FOR A SNOW EVENT AND SIGNIFICANTLY COLDER TEMPS.
THE GFS ON THE OTHER HAND IS LESS SLOWER AND CLOSES OFF THE SYSTEM
NEAR THE FOUR CORNERS REGION DURING THE DAY ON SUNDAY WITH COLD
FRONT HOLDING OFF UNTIL SUNDAY AFTN/NIGHT. THE GFS ENSEMBLE MEAN
IS CLOSER TO THE 00Z ECMWF THAN THE 00 GFS...WITH THE MORE
PROGRESSIVE NATURE OF THE TROUGH. BOTH THE ECMWF AND GFS ENSEMBLE
MEAN ADVERTISE A NICE SURGE OF SIGNIFICANTLY COLDER AIR WITH H85
TEMPS POTENTIALLY DROPPING TO -10C TO -15C BY 12Z MONDAY. THIS
WILL BE A SYSTEM TO KEEP AN EYE ON AS IT IS STILL WELL INTO THE
EXTENDED PERIODS...BUT COULD FINALLY BRING IN SOME WINTRY
CONDITIONS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
1222 PM UPDATE/AVIATION/0954 AM UPDATE...BRYANT
AREA FORECAST DISCUSSION
NWS BUFFALO NY
739 PM EST TUE DEC 4 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS WESTERN AND CENTRAL NEW YORK THIS EVENING
BRINGING WIDESPREAD RAIN FOLLOWED BY SIGNIFICANTLY COOLER
TEMPERATURES. LOOK FOR A SEASONABLY CHILLY DAY ON WEDNESDAY WITH A
CHANCE OF LIGHT LAKE EFFECT SNOW SHOWERS FOLLOWED BY FAIR WEATHER
AND SEASONABLY COOL TEMPERATURES THURSDAY AS HIGH PRESSURE CROSSES
THE REGION.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
THE MAIN STORY TONIGHT WILL BE THE PASSAGE OF A COLD FRONT. THE
MAIN FRONTAL BOUNDARY HAS ALREADY REACHED CENTRAL NEW
YORK EARLY THIS EVENING. THERE IS STILL A FAIRLY SOLID AREA OF
RAIN EXTENDING ALONG AND BEHIND THIS INITIAL BOUNDARY...WITH RAIN
FALLING ACROSS NEARLY ALL OF WESTERN NEW YORK EARLY THIS EVENING.
THIS COLD FRONT WILL CONTINUE TO PUSH EAST OVERNIGHT...WITH RAIN
ENDING RATHER QUICKLY FROM WEST TO EAST. BOTH HRRR AND RADAR
TRENDS SHOW THE BACK EDGE OF THIS RAIN MOVING QUICKLY FROM WEST TO
EAST DURING THE EVENING HOURS...WITH RAIN LIKELY TO BE DONE IN
BUFFALO AROUND 900 PM...ROCHESTER 1100 PM...AND THE REST OF THE
CWA BY 200 AM. THIS IS PERHAPS A TAD FASTER THAN PREVIOUS
GRIDS...ONLY BY AN HOUR OR TWO.
MEANWHILE...THERE IS A SECONDARY BOUNDARY BACK ACROSS MICHIGAN.
THIS FRONT HAS A MORE NOTABLE WIND SHIFT TO THE NORTHWEST...BUT
LITTLE IN THE WAY OF WEATHER ASSOCIATED WITH IT. EXPECT A PARTIAL
CLEARING IN MOST AREAS BEHIND THE INITIAL FRONT...FOLLOWED BY A
WINDS SHIFT AND INCREASE IN CLOUDS LATE TONIGHT. WITH TEMPERATURES
ALOFT STILL ABOVE -6C AT 09Z...DO NOT EXPECT ANY LAKE RESPONSE
THROUGH DAYBREAK. THERE WILL...HOWEVER BE DROPPING TEMPERATURES WITH
READINGS DROPPING BELOW FREEZING BY SUNRISE WEST OF THE GENESEE
VALLEY WITH LOWS IN THE MID 30S TO THE EAST.
COLDER AIR WILL BUILD BEHIND THIS SECONDARY FRONT WEDNESDAY
MORNING...WHICH WILL REINFORCE THE COLD AIR...RESULTING IN
TEMPERATURES THAT WILL GENERALLY HOLD STEADY OR EVEN DROP A COUPLE
OF DEGREES INTO MID TO LOWER 30S WITH SOME LOCATIONS ACROSS HIGHER
ELEVATIONS POTENTIALLY DROPPING INTO THE UPPER 20S DURING THE DAY.
REGARDING THE POTENTIAL FOR LAKE EFFECT SNOWS ON WEDNESDAY...WNW
FLOW COUPLED WITH THE ADVECTION OF VERY DRY AIR ALOFT WILL
SUBSTANTIALLY LIMIT THE DEVELOPMENT OF ANY LES SHOWERS OFF OF LAKE
ERIE WITH FLURRIES AT BEST. OFF OF LAKE ONTARIO...SLIGHTLY HIGHER
EQUILIBRIUM LEVEL AND LONGER FETCH MAY ALLOW FOR SOME VERY LIGHT
SNOW SHOWERS TO DEVELOP BY THE AFTERNOON...HOWEVER ONCE AGAIN THE
MAIN ISSUE WILL BE A POTENTIAL LACK OF SATURATION IN THE DENDRITIC
GROWTH ZONE. GIVEN HOW DRY THE AIR ALOFT IS PROGGED TO BE...AT THIS
POINT ONLY EXPECT VERY LIGHT SNOW SHOWERS OR FLURRIES WITH
ACCUMULATIONS LIMITED TO A DUSTING AT BEST.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
A BROAD PACIFIC FLOW ALOFT WITH A PREDOMINANT SOUTHERLY GULF FLOW IN
THE LOW LEVELS CAN ONLY MEAN ONE THING FOR THIS PERIOD...MORE MILD
WEATHER. THE ONLY REAL COLD AIR OF NOTE IS SITUATED ON THE OTHER
SIDE OF THE POLE IN SIBERIA...AND EVEN THAT AIRMASS WILL UNDERGO
SIGNIFICANT WARMING DURING THE COURSE OF THE WEEK.
IN ANY CASE...A ZONAL PACIFIC FLOW ALONG THE CANADIAN BORDER AT THE
START OF THIS PERIOD WILL GRADUALLY EVOLVE INTO A BROAD BASED TROUGH
OVER THE WESTERN STATES BY THE START OF THE WEEKEND. SEVERAL STRONG
SHORTWAVES WILL EJECT OUT OF A PERSISTENT VORTEX OVER THE GULF OF
ALASKA...AND THESE FEATURES WILL CARVE OUT THE BROAD TROUGH WHILE
FLAT RIDGING WILL TAKE SHAPE DOWNSTREAM OVER EASTERN CANADA AND NEW
ENGLAND. WHILE THIS PATTERN WILL OPEN THE DOOR FOR SOME CANADIAN AIR
TO SETTLE SOUTH ACROSS THE WESTERN STATES...IT IS WORTH NOTING THAT
THE AIRMASS WILL BARELY BE SEASONABLY COLD. THERE IS JUST NO REAL
COLD AIR TO BE TAPPED.
AS FOR THE DETAILS...
EXPANSIVE HIGH PRESSURE WILL BE CENTERED OVER THE LOWER GREAT LAKES
WEDNESDAY NIGHT WITH MODERATELY STRONG WARM ADVECTION BECOMING
ESTABLISHED JUST AHEAD OF A FLAT MID LEVEL RIDGE. WHILE THERE WILL
BE SOME ISENTROPIC LIFT PRESENT...THE DEARTH OF MID LEVEL MOISTURE
SHOULD STILL ENABLE US TO EXPERIENCE A CLEAR STARLIT NIGHT WITH
SEASONABLE TEMPERATURES.
THURSDAY PROMISES TO BE A FAIRLY NICE EARLY DECEMBER DAY AS
SUBSIDENCE WILL REMAIN OVER THE REGION DESPITE THE SFC HIGH DRIFTING
EAST ACROSS NEW ENGLAND. WHILE CIRRUS CLOUDS SHOULD THICKEN FROM
WEST TO EAST...CONTINUED WARM ADVECTION WITHIN THE RETURN FLOW
AROUND THE BACKSIDE OF THE HIGH WILL SEND OUR TEMPERATURES BACK TO
ABOVE NORMAL LEVELS.
AS A MOIST SOUTHERLY FLOW DEEPENS OVER OUR AREA THURSDAY NIGHT...A
MID LEVEL DISTURBANCE WILL CROSS THE MID WEST AND BRING SHOWERS TO
OUR DOORSTEP BY DAYBREAK FRIDAY. SINCE H85 TEMPS WILL BE WELL ABOVE
ZERO C...ANY PCPN THAT FALLS OVER THE SOUTHWEST CORNER OF THE STATE
DURING THE NIGHTTIME HOURS SHOULD DO SO IN THE FORM OF RAIN.
FRIDAY WILL PROVE TO BE AN UNSETTLED DAY...ESPECIALLY OVER THE
WESTERN COUNTIES WHERE RAIN SHOWERS WILL BE THE MOST WIDESPREAD. THE
AFOREMENTIONED MID LEVEL DISTURBANCE WILL LIFT ACROSS OUR REGION IN
ADVANCE OF A WEAK PACIFIC FRONTAL SYSTEM THAT WILL BE APPROACHING
FROM MICHIGAN. THE LIFT PROVIDED BY THIS FEATURE WITHIN A MOISTURE
RICH ENVIRONMENT (PWAT >200 PERCENT OF NORMAL) SHOULD SUPPORT
RAISING THE POPS TO LIKELY...AT LEAST OVER THE WESTERN COUNTIES.
MEANWHILE...FRIDAY WILL BE YET ANOTHER MILD DAY WITH TEMPERATURES
ONCE AGAIN CLIMBING WELL INTO THE 40S (NR 50 GEN VALLEY).
A WEAK FRONTAL BOUNDARY WILL SLOWLY CROSS OUR REGION ON FRIDAY
NIGHT...AND THIS SHOULD KEEP INCLEMENT CONDITIONS IN PLACE WITH MORE
RAIN SHOWERS EXPECTED.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
THERE ARE TWO THINGS THAT YOU WILL BE ABLE TO HANG YOUR HAT ON
DURING THIS PERIOD. ONE...ITS GOING TO BE UNSETTLED. TWO...OUR
TEMPERATURES WILL LARGELY REMAIN ABOVE NORMAL. ITS THE DETAILS OF
THIS ACTIVE PATTERN THAT WILL BE CHALLENGING TO NAIL DOWN.
THE LAST OF A SERIES OF VIGOROUS SHORTWAVES ROTATING ABOUT A CLOSED
LOW OVER THE GULF OF ALASKA WILL EJECT ACROSS BRITISH COLUMBIA ON
SATURDAY AND PROCEED TO DIVE ACROSS THE INTER-MOUNTAIN WEST TO THE
FOUR CORNERS AREA BY SUNDAY EVENING. THIS WILL AMPLIFY THE BROAD
BASED TROUGH OVER THE WESTERN STATES WHILE ALLOWING A LITTLE TASTE
OF WINTER (SEASONABLY COLD AIR) TO SETTLE ACROSS THE PLAINS.
MEANWHILE OVER THE LOWER GREAT LAKES...HGTS ALOFT WILL REMAIN
RELATIVELY CONSTANT WHILE A WARM LOW LEVEL FLOW FROM THE GULF WILL
BASICALLY STAY INTACT.
AT THE SFC...A NEARLY STALLED FRONTAL BOUNDARY ALONG THE OHIO VALLEY
WILL THEN SERVE AS A PATHWAY FOR AT LEAST TWO ORGANIZED STORM
SYSTEMS TO LIFT OUT OF THE SOUTHERN PLAINS TO OUR FORECAST AREA.
THESE AREAS OF LOW PRESSURE WILL HAVE PLENTY OF GULF MOISTURE TO TAP
INTO...SO AS THESE FEATURES MAKE THEIR WAY NORTHEAST OUT OF THE OHIO
VALLEY TO OUR REGION...WE CAN EXPECT A PROLONGED STRETCH OF
UNSETTLED WEATHER. THIS WILL RANGE FROM SPOTTY LIGHT SHOWERS TO
LONGER PERIODS OF STEADY RAIN. NOTE...NO SNOW DURING THIS PERIOD.
GIVEN THE DISCREPANCIES IN THE VARIOUS MODEL PACKAGES AND THE LACK
OF RUN TO RUN CONSISTENCY...WILL NOT GET INTO THE TIMING AND TRACKS
OF THE VARIOUS SOLUTIONS. AS A RESULT OF THIS...WILL NOT TRY TO GET
ANY MORE SPECIFIC ABOUT ANY POSSIBLE WIND THREATS TOWARDS THE END OF
THE FORECAST PERIOD. WILL ONLY POINT OUT THAT THE FORECAST DURING
THIS PERIOD WILL BE BASED ON A 3:1 BLEND BETWEEN THE ECMWF AND HPC.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
A COLD FRONT WILL PUSH ACROSS THE REGION THIS EVENING. THIS FRONT
WILL BRING A PERIOD OF RAIN AND AN HOUR OR TWO OF MVFR CIGS IS
POSSIBLE AS THIS FRONT MOVES THROUGH...OTHERWISE..CONDITIONS
SHOULD MAINLY BE MVFR/VFR DURING THE EVENING HOURS. CONDITIONS
SHOULD IMPROVE TO VFR BEHIND THIS FRONT.
A SECONDARY FRONTAL BOUNDARY WILL CROSS FROM WEST TO EAST BETWEEN
06Z AND 12Z. THERE WILL BE NO PRECIPITATION WITH THIS FRONT...BUT
AS TEMPERATURES ALOFT COOL...THIS WILL PROBABLY BRING CIGS OF
AROUND 3000 FEET BEHIND IT.
THESE WILL LIFT ON WEDNESDAY. THERE MAY BE SCATTERED LIGHT LAKE
EFFECT SHOWERS ON WEDNESDAY SOUTHEAST OF THE LAKES...HOWEVER
CONDITIONS SHOULD GENERALLY REMAIN VFR.
OUTLOOK...
THURSDAY...VFR.
FRIDAY AND SATURDAY...MVFR WITH SHOWERS.
SUNDAY...VFR WITH A CHANCE SHOWERS.
MONDAY...MVFR WITH SHOWERS.
&&
.MARINE...
SMALL CRAFT CONDITIONS WILL PERSIST ON LAKE ERIE TONIGHT AS A COLD
FRONT CROSSES THE LAKE BRINGING GUSTY WESTERLY WINDS AND BUILDING
WAVES. LOOK FOR SCA CONDITIONS TO DEVELOP ON LAKE ONTARIO LATER
TONIGHT AS THE FRONT CROSSES THAT LAKE. SCA CONDITIONS WILL PERSIST
THROUGH TOMORROW ON LAKE ERIE AND TOMORROW NIGHT ON LAKE ONTARIO
BEFORE HIGH PRESSURE BUILDING INTO THE REGION BRINGS A PERIOD OF
CALMER CONDITIONS FOR THE MIDWEEK WITH INCREASING SOUTHERLY FLOW BY
THE END OF THE WEEK.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST WEDNESDAY FOR LEZ040-041.
SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR LEZ020.
SMALL CRAFT ADVISORY FROM 3 AM WEDNESDAY TO 4 AM EST
THURSDAY FOR LOZ043-044.
SMALL CRAFT ADVISORY FROM 3 AM WEDNESDAY TO MIDNIGHT EST
WEDNESDAY NIGHT FOR LOZ042-045.
&&
$$
SYNOPSIS...WOOD
NEAR TERM...AR/WOOD
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...APFFEL
MARINE...WOOD
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1245 AM EST MON DEC 3 2012
.SYNOPSIS...
WELL ABOVE NORMAL TEMPERATURES ARE EXPECTED THROUGH THE EARLY PART
OF THIS WEEK AS HIGH PRESSURE DRIFTS ACROSS THE AREA. A COLD FRONT
WILL CROSS THE EASTERN CAROLINAS ON WEDNESDAY AND MAY BRING A FEW
SHOWERS. NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES ARE EXPECTED
BEHIND THE COLD FRONT FOR LATE WEEK. UNSETTLED WEATHER MAY RETURN
NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 AM MONDAY...FOG OF VARYING THICKNESS AND EXTENT
FORMING WHEREVER THERE IS A BREAK IN THE CLOUDS EARLY THIS
MORNING. THIS IS MUCH AS EXPECTED. NO SUBSTANTIAL CHANGES TO THE
FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSIONS FOLLOW:
TEMPERATURES NEAR THE COAST HAVE FALLEN QUICKLY THIS EVENING AND
ALREADY ARE WITHIN A COUPLE DEGREES OF FORECAST LOWS. FARTHER
INLAND WHERE STRATOCUMULUS CLOUDS HAVE BEEN MORE PERVASIVE
TEMPERATURES ARE ACTUALLY A COUPLE DEGREES HIGHER THAN WAS
FORECAST FOR 02Z. STANDARD INFRARED SATELLITE IS NOT SHOWING MUCH
OF THE CLOUD COVER INLAND...HOWEVER THE 11-3.9 MICRON DIFFERENCE
IMAGERY IS SHOWING SCATTERED TO BROKEN STRATOCUMULUS EXTENDING
FROM FLORENCE NORTHEASTWARD ACROSS LUMBERTON AND ELIZABETHTOWN.
THIS IS AT LEAST 40-50 MILES FARTHER NORTH THAN WHERE THE 18Z
SYNOPTIC MODELS AND THE LATEST SEVERAL RUC RUNS INDICATED MAXIMUM
ISENTROPIC LIFT WOULD OCCUR. EARLIER SHOWER ACTIVITY HAS
DISSIPATED WITH STABILIZATION OF THE LOWER TROPOSPHERE...AND THERE
IS NO IMPETUS FOR ADDITIONAL SHOWER ACTIVITY THROUGH THE NIGHT.
WITH TEMPERATURE-DEWPOINT SPREADS AT THE SURFACE CLOSING UP TO ZERO
AT THE COAST...TEMPERATURE CURVES SHOULD FLATTEN OUT SHORTLY. ANY
STRATOCUMULUS ADVECTING EASTWARD FROM POINTS FARTHER INLAND COULD
ACTUALLY CAUSE A TEMPORARY RISE IN SURFACE TEMPERATURE. THE BIGGEST
QUESTION FOR THE REMAINDER OF THE NIGHT IS FOG. VISIBILITIES ARE
ALREADY DROPPING AT GEORGETOWN...CONWAY...AND IN NORTH MYRTLE BEACH.
FOG SHOULD BECOME MORE WIDESPREAD OVER THE NEXT SEVERAL HOURS...BUT
WILL AVOID AREAS WITH RESTRICTED RADIATIONAL COOLING FROM
SUBSTANTIAL CLOUD COVER. IF A DENSE FOG ADVISORY BECOMES NEEDED
OVERNIGHT THE MOST LIKELY LOCATIONS WOULD BE GEORGETOWN AND HORRY
COUNTIES IN SOUTH CAROLINA THROUGH COASTAL SOUTHEASTERN NORTH
CAROLINA. PREVIOUS DISCUSSION FROM 630 PM FOLLOWS...
TEMPERATURES AND DEWPOINTS WILL BOTH REMAIN ABOVE NORMAL FOR
DECEMBER AS A NEARLY-SUBTROPICAL AIRMASS IS LIFTED NORTH BY HIGH
PRESSURE LOCATED JUST OFFSHORE. ISOLATED SHOWERS JUST NORTH OF
FLORENCE ARE THE RESULT OF A POCKET OF INSTABILITY BETWEEN 850 AND
700 MB AIDED BY WEAK ISENTROPIC LIFT ALONG THE 295K ISENTROPIC
SURFACE. ALTHOUGH THE INSTABILITY IS FORECAST TO DISSIPATE THIS
EVENING...ISENTROPIC LIFT IS EXPECTED TO CONTINUE ALONG 295K THETA
WHICH SHOULD KEEP SCATTERED TO BROKEN STRATOCUMULUS CLOUDS IN
PLACE...ESPECIALLY FROM FLORENCE EAST ACROSS MYRTLE BEACH INTO
SOUTHPORT.
WITH SUCH RICH BOUNDARY LAYER MOISTURE UNDERNEATH THE ISENTROPIC
LIFT ALOFT...IT WILL NOT TAKE LONG FOR RELATIVE HUMIDITY DOWN HERE
AT THE SURFACE TO APPROACH 100 PERCENT. COOL SOIL TEMPERATURES WILL
AID THAT PROCESS AS WELL...AND I ANTICIPATE AREAS OF FOG TO DEVELOP
LATE THIS EVENING AND OVERNIGHT. IT REMAINS POSSIBLE SOME OF THIS
FOG COULD BECOME QUITE DENSE. LOWS TONIGHT SHOULD FALL TO WITHIN A
COUPLE DEGREES OF 50 AREA-WIDE...ABOUT 10 DEGREES ABOVE NORMAL.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...INCREASINGLY DEEP 500MB LONGWAVE TROUGH
DEVELOPING ACROSS THE MIDDLE PART OF THE COUNTRY FORCES DOWNSTREAM
RIDGING ACROSS THE CAROLINAS...WITH 500MB HEIGHTS RISING ABOVE 580DM
MONDAY...AND ONLY A SLIGHT DECREASE ON TUESDAY. THIS COMBINED
WITH HIGH PRESSURE PERSISTING AT THE SURFACE CREATES WELL ABOVE
NORMAL TEMPS WITH AMPLE DECEMBER SUNSHINE THROUGH THE SHORT TERM.
SURFACE HIGH INITIALLY CENTERED NEARLY OVERHEAD WILL GRADUALLY SHIFT
EAST...BECOMING DISPLACED OFFSHORE ON TUESDAY. THIS MOVEMENT IS DUE
TO THE EASTWARD PROGRESSION OF THE UPPER TROUGH AND ASSOCIATED COLD
FRONT...WHICH WILL APPROACH FROM THE WEST AT THE END OF THE PERIOD.
WHILE HIGH SITS OVERHEAD MONDAY...WEAK RETURN FLOW WILL EXIST AT THE
SURFACE...BUT MID LEVEL FLOW WILL REMAIN W/NW. THIS IS A WARMING
/DOWNSLOPE/ TRAJECTORY...SO 850MB TEMPS AROUND 9C AND 1000-850MB
THICKNESSES OF 1370M WILL HELP DRIVE MAX TEMPS WELL INTO THE 70S
AWAY FROM THE IMMEDIATE BEACHES. AS HIGH DRIFTS OFFSHORE MONDAY
NIGHT...SOUTHERLY RETURN FLOW WILL CONTINUE...AND MINS WILL FALL
ONLY TO AROUND 50 DEGREES.
WHILE LOW LEVEL THICKNESSES REMAIN SIMILAR ON TUESDAY...INCREASED
HIGH LEVEL CLOUD COVER AHEAD OF THE COLD FRONT...GREATER LOW LEVEL
MOISTURE...AND SLIGHTLY REDUCED 500MB HEIGHTS WILL KEEP MAX TEMPS
MARGINALLY LOWER THAN ON MONDAY. STILL A VERY WARM AND DRY DAY
HOWEVER...WITH AFTN MAXIMUMS RISING INTO THE LOW 70S. PRESSURE
GRADIENT TIGHTENS AHEAD OF THE ADVANCING FRONT TUESDAY NIGHT...SO
WINDS STAY ELEVATED AND NIGHTTIME LOWS WILL FALL ONLY INTO THE LOW
50S.
ALTHOUGH FORECAST POP WILL REMAIN SILENT THROUGH THE
PERIOD...GUIDANCE IS PERSISTENT WITH SOME VERY LIGHT SHOWER ACTIVITY
EACH NIGHT. THIS IS LIKELY ASSOCIATED WITH MOIST ADVECTION BRINGING
SHOWERS ONSHORE...AND ALTHOUGH PROFILE MOISTURE IS CONFINED TO THE
LOWEST 5 KFT OR SO...SOME ISENTROPIC LIFT ALONG THE 295K SURFACE IS
EVIDENT EACH NIGHT. FEEL THE CHANCE FOR MEASURABLE PRECIP IS QUITE
LOW...SO WILL KEEP POP JUST BELOW THRESHOLD FOR NOW.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 300 PM SUNDAY...FORECAST CHALLENGE WILL COME LATER IN THE
PERIOD WHEN A BROAD CYCLONIC FLOW DEVELOPS ACROSS THE CENTRAL PART
OF THE CONUS WITH A SUBTLE SOUTHWEST FLOW ACROSS OUR CWA. AT THE
SURFACE...A FRONT WILL BE POSITIONED ACROSS THE
TENNESSEE/MISSISSIPPI VALLEY. WITH HPCS POSITION OF THE FRONT WELL
TO THE WEST...HAVE REMOVED POPS FROM THE FORECAST FOR THURSDAY
INTO FRIDAY ALTHOUGH RETURN FLOW COULD SPARK A FEW LIGHT SHOWERS
OFFSHORE. THE POSSIBILITY OF SEA FOG CANNOT BE RULED OUT WITH THIS
TYPE OF SCENARIO AS WELL. NO CHANGES TO TEMPERATURE FORECAST.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 06Z...EXPECT MVFR/IFR DUE TO FOG AND/OR LOW CIGS OVERNIGHT
INTO THE MORNING HOURS. OTHERWISE EXPECT VFR.
ALREADY THERE HAVE BEEN AREAS EXPERIENCING MVFR/IFR DUE TO FOG AND
LOW CIGS. EXPECT THIS PATTERN TO CONTINUE THROUGH THE OVERNIGHT
HOURS WITH LIGHT WINDS AND PARTLY TO MOSTLY CLOUDY SKIES. A TREND
WITH THE RESTRICTIONS WILL BE ITS VARIABILITY...VARYING FROM IFR TO
VFR...BACK TO MVFR IS AREAS. LATEST TIME HEIGHT AND FCST SOUNDING
ANALYSIS CONTINUE TO SUPPORT THESE CONDITIONS THROUGH THE MORNING
HOURS. FOR NOW...HAVE KEPT WITH CURRENT TREND OF PREVIOUS FORECAST
BY PROJECTING THE DETERIORATING WEATHER CONDITIONS DUE TO BOTH FOG
AND LOW CIGS. ATTM...EXPECT CONDITIONS TO IMPROVE TO MVFR AREA-WIDE
BY MID MORNING...PREVAILING AS VFR BY MID TO LATE MORNING. FOR THE
REST OF MONDAY EXPECT VFR WITH SCT MID LEVEL CLOUDS AND SOUTHWEST
WINDS 5-8 KTS...BECOMING LIGHT INTO MONDAY NIGHT.
EXTENDED OUTLOOK...MODERATE CONFIDENCE FOR MORNING MVFR/IFR FOG
THROUGH TUESDAY WITH A PERSISTENT MOIST LOW-LEVEL ONSHORE FLOW. A
SLIGHT CHANCE OF SHOWERS LATE TUESDAY INTO WEDNESDAY ASSOCIATED WITH
A COLD FRONT. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 AM MONDAY...MUCH AS BEFORE...NO ADDITIONAL SIGNIFICANT
CHANGES ARE NEEDED TO THE MARINE FORECAST EARLY THIS MORNING. SEAS
AT THE FRYING PAN SHOALS BUOY STILL AROUND 4 FT...WITH A LITTLE
MORE THAN HALF THAT MAKING IT TO THE BEACHES ACCORDING TO THE
WAVE GAUGE AT THE OCEAN CREST PIER ON OAK ISLAND. PREVIOUS FULL
DISCUSSION FROM 300 PM FOLLOWS...
AS HIGH PRESSURE REORIENTS ITSELF...WINDS WILL CONTINUE TO VEER FROM
E AND SE INTO THIS EVE...TO SW OVERNIGHT. WIND SPEEDS WILL BE 10 KT
OR LESS. SEAS WILL RANGE FROM 2 TO 3 FT. AN ESE 8 TO 9 SECOND SWELL
CONTINUES TO BE SAMPLED BY THE BUOYS AND NO CHANGES ARE EXPECTED
THIS PERIOD.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 PM SUNDAY...HIGH PRESSURE EXTENDING ACROSS THE WATERS
PERMITS ONLY LIGHT WINDS THROUGH THE PERIOD. WINDS WILL BE LIGHT AND
VARIABLE MONDAY AND MUCH OF TUESDAY...BEFORE VEERING TO THE SW AND
INCREASING TO AROUND 10 KTS TUESDAY NIGHT WELL AHEAD OF A COLD
FRONT. SEAS THEN ARE PRIMARILY SWELL DOMINATED...GENERATED FROM A
CONTINUING 3FT/8SEC SE GROUND SWELL...AND WILL BE 2-3 FT MONDAY.
SLIGHT ENHANCEMENT IN WAVE HEIGHTS EXPECTED LATE TUESDAY AS A 2-3FT
SW WIND WAVE DEVELOPS ON TOP OF THE PERSISTENT SWELL...BUT
SIGNIFICANT SEAS ARE STILL EXPECTED TO REMAIN 2-4 FT.
LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 300 PM SUNDAY...EXPECT A MODEST SOUTHWEST FLOW OF TEN KNOTS
OR SO AT THE BEGINNING OF THE PERIOD AHEAD OF A COLD FRONT TO THE
WEST. THE FRONT MOVES ACROSS THE WATERS WEDNESDAY AFTERNOON WITH A
NORTHERLY FLOW OF 10-15 KNOTS ENSUING. THE WINDS WILL REMAIN
ELEVATED RELATIVELY SPEAKING FOR MOST OF THE DAY THURSDAY IN A
10-15 KNOT RANGE WHILE VEERING TO THE NORTHEAST A BIT. FOR
FRIDAY...HIGH PRESSURE QUICKLY SLIPS OFFSHORE WITH A SOUTHEASTERLY
RETURN FLOW DEVELOPING. THE BIG STORY WITH SEAS WILL BE THE
POSSIBILITY OF SMALL CRAFT CONDITIONS THURSDAY AS THE NE FETCH
PERSISTS FOR QUITE SOME TIME. VALUES DROP BACK FRIDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...REK/RJD
SHORT TERM...JDW
LONG TERM...SHK
AVIATION...SGL
MARINE...REK/RJD/JDW/SHK
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
204 AM EST MON DEC 3 2012
.SYNOPSIS...
A DIFFUSE FRONTAL BOUNDARY OVER CENTRAL PENNSYLVANIA TODAY WILL
PIVOT AND LIFT BACK TO THE NORTH AS A WARM FRONT TONIGHT. BROAD
SOUTHWEST FLOW WILL BRING UNSEASONABLY MILD AIR INTO THE REGION
THROUGH TUESDAY...WITH TEMPERATURES 10 TO 20 DEGREES ABOVE NORMAL.
A COLD FRONT WILL PUSH THROUGH THE REGION TUESDAY NIGHT ACCOMPANIED
BY A BAND OF RAIN SHOWERS. SEASONABLY COLD AND BRISK CONDITIONS
BEHIND THE FRONT WILL PREVAIL WEDNESDAY INTO THURSDAY...WITH SOME
LAKE EFFECT SNOW SHOWERS OVER THE NORTHWEST MOUNTAINS DOWNWIND OF
LAKE ERIE.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
WATER VAPOR LOOP SHOWS POTENT SHORTWAVE MOVING EASTWARD ACROSS
SOUTHERN QUEBEC AT 03Z. WANING LG SCALE FORCING BEHIND THIS
FEATURE HAS CAUSED SHOWERS TO DIMINISH ACROSS CENTRAL PA AND
LATEST RAP DATA AND RADAR TRENDS SUGGEST ANY REMAINING -SHRA OR
DRIZZLE AFTER MIDNIGHT WILL BE CONFINED MAINLY TO THE UPSLOPE
AREAS ALONG THE LAUREL HIGHLANDS.
SFC COLD FRONT...APPROACHING THE NORTHERN LK ERIE SHORE AT
03Z...WILL SAG INTO THE N MTNS LATE TONIGHT. OVERCAST SKIES AND A
SW BREEZE WILL KEEP IT VERY MILD OVERNIGHT WITH LOWS MOSTLY IN THE
M/U40S. PLENTY OF LOW LVL MOISTURE AND LGT WINDS WILL RESULT IN
AREAS OF FOG. SOME OF THE FOG COULD BECOME DENSE...ESP OVR THE W
MTNS...WHERE A LGT SW WIND ASCENDS THE HIGH TERRAIN.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/...
RIDGING AT THE SFC AND ALOFT SHOULD SUPPLY CENTRAL PA WITH DRY WX
ON MONDAY. HOWEVER...PLENTY OF LOW LVL MOISTURE WILL REMAIN
TRAPPED BENEATH SUBSIDENCE INVERSION...RESULTING IN A GOOD DEAL OF
CLOUD COVER...ESP ACROSS THE W MTNS WHERE A LIGHT W WIND ASCENDS
THE HIGH TERRAIN.
DESPITE THE CLOUD COVER...CENTRAL PA WILL BE ON THE EDGE OF AN
UNSEASONABLY WARM AIR MASS CENTERED OVR THE MIDWEST/OHIO VALLEY.
LATEST GUIDANCE CONTINUES TO SUGGEST TEMPS WILL REACH CLOSE TO
60F OVER MUCH OF CENTRAL PA MON AFTN.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
EXTENSIVE ZONAL UPPER FLOW ACROSS MUCH OF THE LOWER 48 IS
FORECAST TO CONTINUE THROUGH MUCH OF THE LONG TERM PERIOD. THIS
FLOW PATTERN WILL KEEP LARGE SCALE COLD WEATHER AT BAY...BUT SOME
VISITS FROM WINTRY WEATHER ARE NOT OUT OF THE QUESTION. SEVERAL
PIECES OF SHORTWAVE ENERGY MOVING THROUGH THE FLOW WILL LEAD TO
CHANCES FOR PCPN DURING THE WEEK AHEAD.
TUESDAY/S HIGHS WILL BE 18-20F ABOVE NORMAL...AND PERHAPS AS MUCH
AS 25F ABOVE NORMAL ACROSS LAUREL HIGHLANDS AND ADJACENT SOUTH-
CENTRAL VALLEYS AHEAD OF THE NEXT APPROACHING COLD FRONT.
THE POTENT SHORTWAVE CRASHING ONTO THE NW COAST TODAY /SUNDAY/ WILL
MOVE QUICKLY EAST ACROSS SOUTHERN CANADA AND AMPLIFY AS IT SLIDES
THROUGH ONTARIO PROVINCE DURING THE MIDWEEK PERIOD. THE ASSOCIATED
COLD FRONT WILL BRING A SEVERAL HOUR PERIOD OF RAIN SHOWERS TO THE
REGION LATE TUESDAY/TUESDAY NIGHT...WITH MOST MODEL GUIDANCE AND
ENSEMBLES INDICATING A MEAN QPF OF ABOUT 2-3 TENTHS.
THE SURGE OF MUCH COOLER AIR IN THE WAKE OF THE FRONT WILL SUPPORT
SCATTERED SNOW SHOWERS ACROSS MAINLY THE MTNS OF NWRN PENN LATE
TUESDAY NIGHT AND WEDNESDAY...WITH MINOR ACCUMULATIONS OF A COATING
TO AND INCH OR TWO POSSIBLE /NEAR AND TO THE WEST OF KBFD/.
ENSEMBLE MOS TEMPS STAY A FEW...TO SEVERAL DEG F ABOVE NORMAL FOR
THURSDAY AND FRIDAY AS UPPER HEIGHTS REBOUND ONLY SLIGHTLY...AND A
BUBBLE OF HIGH PRESSURE WITH CP AIR SLIDES SE FROM THE PRAIRIE
PROVINCES OF SCENT CANADA AND REACHES THE NE U.S. COAST THURSDAY
NIGHT.
UNCERTAINTY CLIMBS SIGNIFICANTLY FOR NEXT WEEKEND AS THE NEXT COLD
FRONTAL BOUNDARY SLOWS AND PERHAPS TEMPORARILY STALLS OUT FROM THE
OHIO VALLEY THROUGH THE MID ATLANTIC REGION. LARGE DIVERGENCE ARISES
IN THE QPF PATTERN/FRONTAL LOCATION BETWEEN 00Z/06Z GFS AND
EC...ALONG WITH A LARGE SPREAD IN GEFS /PLUME/ QPF AND SFC-925 MB
TEMPS.
RAIN CHANCES INCREASE BEGINNING LATE FRIDAY NIGHT THROUGH NEXT
WEEKEND...AND COULD POSSIBLY BE MIXED WITH SNOW ACROSS THE NW HALF
OF THE STATE.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
03/06Z - 04/06Z...
RESIDUAL LOW-LEVEL MSTR TRAPPED UNDER A WEAK AREA OF HIGH PRESSURE
WILL RESULT IN WDSPRD LOW CIGS...FOG AND PATCHY DZ EARLY TODAY.
JST SHOULD EXPERIENCE A PROLONGED PERIOD OF VLIFR CONDS...WHILE
OTHER SITES VARY BTWN LOW MVFR AND IFR CONDS. BLYR WARMING/MIXING
AND SHOULD BRING IMPROVING VISBYS BY THE AFTN...BUT LOW CIGS MAY
PERSIST ESP OVR WRN SXNS BASED ON FCST SOUNDING DATA. WINDS WILL
BACK MORE TO THE SOUTH BY THIS EVE. A DIFFUSE WARM FRONTAL ZONE
WILL PIVOT AND LIFT NWD TNT INTO EARLY TUES. SSELY FLOW
INTERSECTING THE FRONTAL ZONE MAY BRING LOW CIGS TO CNTRL AND ERN
SXNS LATE TNT.
OUTLOOK...
TUE...A SEASONABLY STRONG COLD FRONT WILL ENTER THE REGION LATE
IN THE DAY AND CROSS THE AREA OVERNIGHT. EXPECT MAINLY VFR TO
MVFR WITH RAIN SHOWERS. OCNL IFR VIS IN MOD RA. SW-NW WSHFT BY
WED AM.
WED...MVFR WEST WITH SNOW SHOWERS. GUSTY NNW WINDS.
THU-FRI...BCMG VFR WEST. NO SIG WX.
&&
.EQUIPMENT...
IPT OBSERVATION IS NOT BEING TRANSMITTED OR RECEIVED INTO OUR
SYSTEMS. THE PROBLEM IS RELATED TO A FAA COMMS LINE OUTAGE. WE
STILL HAVE DIAL- UP CAPABILITY.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...FITZGERALD/LA CORTE
SHORT TERM...FITZGERALD/LA CORTE
LONG TERM...LAMBERT/GARTNER
AVIATION...STEINBUGL
EQUIPMENT...STEINBUGL
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1102 PM EST SUN DEC 2 2012
.SYNOPSIS...
A WEAKENING COLD FRONT WILL WASH OUT AS IT ENTERS NORTHERN PENNSYLVANIA
TONIGHT. HIGH PRESSURE WILL BUILD ALONG THE EAST COAST EARLY THIS
WEEK. A COLD FRONT WILL PUSH THROUGH THE REGION TUESDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
WATER VAPOR LOOP SHOWS POTENT SHORTWAVE MOVING EASTWARD ACROSS SOUTHERN
QUEBEC AT 03Z. WANING LG SCALE FORCING BEHIND THIS FEATURE HAS
CAUSED SHOWERS TO DIMINISH ACROSS CENTRAL PA AND LATEST RAP DATA
AND RADAR TRENDS SUGGEST ANY REMAINING -SHRA OR DRIZZLE AFTER
MIDNIGHT WILL BE CONFINED MAINLY TO THE UPSLOPE AREAS ALONG THE
LAUREL HIGHLANDS.
SFC COLD FRONT...APPROACHING THE NORTHERN LK ERIE SHORE AT
03Z...WILL SAG INTO THE N MTNS LATE TONIGHT. OVERCAST SKIES AND A
SW BREEZE WILL KEEP IT VERY MILD OVERNIGHT WITH LOWS MOSTLY IN THE
M/U40S. PLENTY OF LOW LVL MOISTURE AND LGT WINDS WILL RESULT IN
AREAS OF FOG. SOME OF THE FOG COULD BECOME DENSE...ESP OVR THE W
MTNS...WHERE A LGT SW WIND ASCENDS THE HIGH TERRAIN.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
RIDGING AT THE SFC AND ALOFT SHOULD SUPPLY CENTRAL PA WITH DRY WX
ON MONDAY. HOWEVER...PLENTY OF LOW LVL MOISTURE WILL REMAIN
TRAPPED BENEATH SUBSIDENCE INVERSION...RESULTING IN A GOOD DEAL OF
CLOUD COVER...ESP ACROSS THE W MTNS WHERE A LIGHT W WIND ASCENDS
THE HIGH TERRAIN.
DESPITE THE CLOUD COVER...CENTRAL PA WILL BE ON THE EDGE OF AN
UNSEASONABLY WARM AIR MASS CENTERED OVR THE MIDWEST/OHIO VALL.
LATEST GUIDANCE CONTINUES TO SUGGEST TEMPS WILL REACH CLOSE TO
60F OVER MUCH OF CENTRAL PA MON AFTN.
&&
.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
EXTENSIVE ZONAL UPPER FLOW ACROSS MUCH OF THE LOWER 48 IS
FORECAST TO CONTINUE THROUGH MUCH OF THE LONG TERM PERIOD. THIS
FLOW PATTERN WILL KEEP LARGE SCALE COLD WEATHER AT BAY...BUT SOME
VISITS FROM WINTRY WEATHER ARE NOT OUT OF THE QUESTION. SEVERAL
PIECES OF SHORTWAVE ENERGY MOVING THROUGH THE FLOW WILL LEAD TO
CHANCES FOR PCPN DURING THE WEEK AHEAD.
TUESDAY/S HIGHS WILL BE 18-20F ABOVE NORMAL...AND PERHAPS AS MUCH
AS 25F ABOVE NORMAL ACROSS LAUREL HIGHLANDS AND ADJACENT SOUTH-
CENTRAL VALLEYS AHEAD OF THE NEXT APPROACHING COLD FRONT.
THE POTENT SHORTWAVE CRASHING ONTO THE NW COAST TODAY /SUNDAY/ WILL
MOVE QUICKLY EAST ACROSS SOUTHERN CANADA AND AMPLIFY AS IT SLIDES
THROUGH ONTARIO PROVINCE DURING THE MIDWEEK PERIOD. THE ASSOCIATED
COLD FRONT WILL BRING A SEVERAL HOUR PERIOD OF RAIN SHOWERS TO THE
REGION LATE TUESDAY/TUESDAY NIGHT...WITH MOST MODEL GUIDANCE AND
ENSEMBLES INDICATING A MEAN QPF OF ABOUT 2-3 TENTHS.
THE SURGE OF MUCH COOLER AIR IN THE WAKE OF THE FRONT WILL SUPPORT
SCATTERED SNOW SHOWERS ACROSS MAINLY THE MTNS OF NWRN PENN LATE
TUESDAY NIGHT AND WEDNESDAY...WITH MINOR ACCUMULATIONS OF A COATING
TO AND INCH OR TWO POSSIBLE /NEAR AND TO THE WEST OF KBFD/.
ENSEMBLE MOS TEMPS STAY A FEW...TO SEVERAL DEG F ABOVE NORMAL FOR
THURSDAY AND FRIDAY AS UPPER HEIGHTS REBOUND ONLY SLIGHTLY...AND A
BUBBLE OF HIGH PRESSURE WITH CP AIR SLIDES SE FROM THE PRAIRIE
PROVINCES OF SCENT CANADA AND REACHES THE NE U.S. COAST THURSDAY
NIGHT.
UNCERTAINTY CLIMBS SIGNIFICANTLY FOR NEXT WEEKEND AS THE NEXT COLD
FRONTAL BOUNDARY SLOWS AND PERHAPS TEMPORARILY STALLS OUT FROM THE
OHIO VALLEY THROUGH THE MID ATLANTIC REGION. LARGE DIVERGENCE ARISES
IN THE QPF PATTERN/FRONTAL LOCATION BETWEEN 00Z/06Z GFS AND
EC...ALONG WITH A LARGE SPREAD IN GEFS /PLUME/ QPF AND SFC-925 MB
TEMPS.
RAIN CHANCES INCREASE BEGINNING LATE FRIDAY NIGHT THROUGH NEXT
WEEKEND...AND COULD POSSIBLY BE MIXED WITH SNOW ACROSS THE NW HALF
OF THE STATE.
&&
.AVIATION /04Z MONDAY THROUGH FRIDAY/...
03Z TAF PACKAGE.
BEEN UPDATING TAFS.
MAINLY CLOUDY OVERNIGHT. LOOKING AT MAINLY IFR AND MVFR
CONDITIONS OVERNIGHT INTO MONDAY MORNING.
SOME IMPROVEMENT BY AFT...BUT HIGH HEIGHTS AND LOW SUN ANGLE
WILL LIKELY RESULT IN SC BEING TRAPPED.
WARM ADVECTION SETS LATE MONDAY INTO EARLY TUE...BEFORE A COLD
FRONT MOVES IN LATE TUE. MORE SHOWERS WITH THE COLD FRONT.
OUTLOOK...
TUE...A STRONG COLD FRONT WILL ENTER THE REGION LATE IN THE DAY
AND PASS OVERNIGHT. VFR TO MVFR WITH RAIN SHOWERS LATE. ISOLD
TSTMS PSBL. WIND-SHIFT BY WED AM.
WED...MVFR WEST WITH SNOW/RAIN SHOWERS.
THU/FRI...NO SIG WX.
&&
.EQUIPMENT...
IPT OBSERVATION NOT BEING TRANSMITTED OR RECEIVED INTO OUR SYSTEMS.
FAA IS AWARE AND WORKING THE ISSUE. WE STILL HAVE DIAL-UP CAPABILITY.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD/LA CORTE
SHORT TERM...FITZGERALD/LA CORTE
LONG TERM...LAMBERT/GARTNER
AVIATION...LA CORTE/MARTIN
EQUIPMENT...LA CORTE
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
1005 AM CST MON DEC 3 2012
.UPDATE...
MINOR UPDATE TO ADJUST SKY COVER FOR TODAY.
&&
.DISCUSSION...
A BROAD UPPER LEVEL RIDGE REMAINS IN PLACE ACROSS THE MID SOUTH
TODAY. ABUNDANT LOW LEVEL MOISTURE CONTINUES TO ADVECT INTO
THE AREA ON SOUTHERLY WINDS. THIS HAS AGAIN RESULTED IN MORNING
STRATUS CLOUD DECK OVER PORTIONS OF THE REGION. OVER EASTERN
SECTIONS THIS STRATUS SHOULD EFFICIENTLY MIX OUT RESULTING IN
PARTLY TO MOSTLY SUNNY SKIES BY THIS AFTERNOON. FURTHER WEST...LOW
CLOUDS MAY PERSIST THROUGH MUCH OF THE DAY WHERE BETTER LOW LEVEL
LIFT ASSOCIATED WITH A STRONGER LOW LEVEL JET WILL RESIDE. PLAN TO
UPDATE THE SKY COVER TO REFLECT THE LATEST FORECAST THINKING.
OTHERWISE...THE REMAINDER OF THE FORECAST APPEARS ON TRACK AND NO
OTHER ELEMENTS WILL BE ADJUSTED AT THIS TIME.
STILL EXPECTING VERY WARM TEMPERATURES THIS AFTERNOON WHICH WILL
BE SEVERAL DEGREES ABOVE NORMAL FOR EARLY DECEMBER. UPDATED
FORECAST GRIDS AND ZONES WILL BE SENT SHORTLY.
JLH
&&
.PREV DISCUSSION... /ISSUED 444 AM CST MON DEC 3 2012/
NEAR RECORD HIGH TEMPERATURES EXPECTED ACROSS THE MIDSOUTH
TODAY... COURTESY OF UNDER LOW AMPLITUDE RIDGING ALOFT AND
SOUTHERLY ONSHORE LOW LEVEL FLOW.
A POSITIVELY TILTED UPPER LEVEL TROF WILL LIFT INTO THE GREAT
LAKES... OHIO VALLEY AND LOWER MS RIVER VALLEY TUESDAY. AN ASSOCIATED
SURFACE COLD FRONT WILL DROP THROUGH THE MIDSOUTH ON TUESDAY...
PROVIDING FOCUS FOR SHOWERS AND ISOLATED THUNDERSTORMS. MIXED
LAYER CAPES TO 750 J/KG AND MODEST WIND SHEAR MAY SUPPORT A AN
EMBEDDED STRONG THUNDERSTORM OR TWO. NO SEVERE WEATHER IS ANTICIPATED.
A PACIFIC SURFACE HIGH WILL SETTLE INTO THE MIDSOUTH ON WEDNESDAY.
WITH A GOOD AMOUNT OF SUNSHINE...POST FRONTAL AFTERNOON TEMPS
WILL WARM TO READINGS 7 TO 10 DEGREES ABOVE NORMAL.
THURSDAY NIGHT SHOULD SEE A WARM FRONT LIFT NORTH THROUGH THE
MIDSOUTH... INCREASING SURFACE DEWPOINTS BACK INTO THE 50S BY FRIDAY
AFTERNOON. A 90KT 250MB JET STREAK MAY ENHANCE THE CHANCES FOR WARM
SECTOR SHOWERS ALONG AND NORTH OF THE ADVANCING WARM FRONT THURSDAY
NIGHT AND FRIDAY. BETTER FOCUS FOR RAIN LATE FRIDAY WILL OCCUR
OVER THE OHIO VALLEY...NEAR THE POSITION OF THE SURFACE WARM FRONT.
BOTH 00Z GFS AND ECMWF KEEP THE MIDSOUTH IN THE MILD...RELATIVELY
HUMID AND WELL MIXED GULF AIRMASS THROUGH SUNDAY. GFS MEX GUIDANCE
TEMPS AND DEWPOINTS APPEAR REASONABLE AND MAY EVEN BE CONSERVATIVELY
COOL.
SIMILAR TO THE PAST SEVERAL DAYS... ECMWF AND GFS MODELS CONTINUED
TO SHOW POOR AGREEMENT AND CONTINUED TO EXHIBIT GREATER THAN
NORMAL RUN TO RUN INCONSISTENCIES BEYOND 180 HOURS. OF PARTICULAR
NOTE IS THE MODELS/ HANDLING OF A RELATIVELY POTENT SOUTHERN
BRANCH UPPER LEVEL LOW LIFTING THROUGH THE SOUTHERN U.S. NEXT WEEK.
HAVE FOLLOWED A COMPROMISE BETWEEN THE MORE PROGRESSIVE ECMWF AND
SLOWER GFS WITH RESPECT TO THIS SYSTEM...LIFTING THROUGH LATE
MONDAY INTO TUESDAY. BOTH MODELS SUGGEST SOME SEVERE POTENTIAL
EXISTS WITH THIS SYSTEM...BUT IT REMAINS FAR TOO EARLY TO PIN DOWN
TIMING AND MAGNITUDE OF ANY SEVERE POTENTIAL.
PWB
&&
.AVIATION...
12Z TAF SET
IFR/MVFR CIGS CONTINUE TO DEVELOP OVER ARKANSAS AT THIS TIME.
LATEST RUC KEEPS CIGS WEST OF THE MS RIVER THUS HAVE KEPT KMEM VFR
THIS MORNING. KJBR SHOULD BE ONLY TAF SITE THAT EXPERIENCES IFR
CIGS BY 14-15Z THIS MORNING. CIGS WILL GRADUALLY LIFT AFTER
17-18Z. BY 19-21Z...VFR CONDITIONS SHOULD PREVAIL EVERYWHERE. MVFR
CIGS WILL BEGIN TO SPREAD INTO CWA AGAIN AFTER 06Z POSSIBLY LOWER
NEAR KJBR. KJBR COULD SEE A FEW TSRAS DEVELOP AHEAD OF APPROACHING
COLD FRONT AFTER 09Z. IN ADDITION...WOULD NOT BE SURPRISED TO SEE
A FEW ELEVATED TSRAS DEVELOP NEAR KTUP AFTER 8-9Z DUE TO WAA.
STRONG S WINDS EXPECTED AFTER 15Z. SPEEDS WILL INCREASE TO 12-17
KTS WITH HIGHER GUSTS. SPEEDS WILL DIE DOWN TO 8-10 KTS AFTER
00Z...POSSIBLY LOWER AT KTUP.
KRM
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 75 62 69 43 / 0 30 90 10
MKL 74 58 67 41 / 0 20 90 10
JBR 74 59 65 40 / 10 70 80 0
TUP 74 56 71 47 / 0 0 80 60
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MEMPHIS TN
545 AM CST MON DEC 3 2012
.DISCUSSION... /ISSUED 444 AM CST MON DEC 3 2012/
NEAR RECORD HIGH TEMPERATURES EXPECTED ACROSS THE MIDSOUTH
TODAY... COURTESY OF UNDER LOW AMPLITUDE RIDGING ALOFT AND
SOUTHERLY ONSHORE LOW LEVEL FLOW.
A POSITIVELY TILTED UPPER LEVEL TROF WILL LIFT INTO THE GREAT
LAKES... OHIO VALLEY AND LOWER MS RIVER VALLEY TUESDAY. AN ASSOCIATED
SURFACE COLD FRONT WILL DROP THROUGH THE MIDSOUTH ON TUESDAY...
PROVIDING FOCUS FOR SHOWERS AND ISOLATED THUNDERSTORMS. MIXED
LAYER CAPES TO 750 J/KG AND MODEST WIND SHEAR MAY SUPPORT A AN
EMBEDDED STRONG THUNDERSTORM OR TWO. NO SEVERE WEATHER IS ANTICIPATED.
A PACIFIC SURFACE HIGH WILL SETTLE INTO THE MIDSOUTH ON WEDNESDAY.
WITH A GOOD AMOUNT OF SUNSHINE...POST FRONTAL AFTERNOON TEMPS
WILL WARM TO READINGS 7 TO 10 DEGREES ABOVE NORMAL.
THURSDAY NIGHT SHOULD SEE A WARM FRONT LIFT NORTH THROUGH THE
MIDSOUTH... INCREASING SURFACE DEWPOINTS BACK INTO THE 50S BY FRIDAY
AFTERNOON. A 90KT 250MB JET STREAK MAY ENHANCE THE CHANCES FOR WARM
SECTOR SHOWERS ALONG AND NORTH OF THE ADVANCING WARM FRONT THURSDAY
NIGHT AND FRIDAY. BETTER FOCUS FOR RAIN LATE FRIDAY WILL OCCUR
OVER THE OHIO VALLEY...NEAR THE POSITION OF THE SURFACE WARM FRONT.
BOTH 00Z GFS AND ECMWF KEEP THE MIDSOUTH IN THE MILD...RELATIVELY
HUMID AND WELL MIXED GULF AIRMASS THROUGH SUNDAY. GFS MEX GUIDANCE
TEMPS AND DEWPOINTS APPEAR REASONABLE AND MAY EVEN BE CONSERVATIVELY
COOL.
SIMILAR TO THE PAST SEVERAL DAYS... ECMWF AND GFS MODELS CONTINUED
TO SHOW POOR AGREEMENT AND CONTINUED TO EXHIBIT GREATER THAN
NORMAL RUN TO RUN INCONSISTENCIES BEYOND 180 HOURS. OF PARTICULAR
NOTE IS THE MODELS/ HANDLING OF A RELATIVELY POTENT SOUTHERN
BRANCH UPPER LEVEL LOW LIFTING THROUGH THE SOUTHERN U.S. NEXT WEEK.
HAVE FOLLOWED A COMPROMISE BETWEEN THE MORE PROGRESSIVE ECMWF AND
SLOWER GFS WITH RESPECT TO THIS SYSTEM...LIFTING THROUGH LATE
MONDAY INTO TUESDAY. BOTH MODELS SUGGEST SOME SEVERE POTENTIAL
EXISTS WITH THIS SYSTEM...BUT IT REMAINS FAR TOO EARLY TO PIN DOWN
TIMING AND MAGNITUDE OF ANY SEVERE POTENTIAL.
PWB
&&
.AVIATION...
12Z TAF SET
IFR/MVFR CIGS CONTINUE TO DEVELOP OVER ARKANSAS AT THIS TIME.
LATEST RUC KEEPS CIGS WEST OF THE MS RIVER THUS HAVE KEPT KMEM VFR
THIS MORNING. KJBR SHOULD BE ONLY TAF SITE THAT EXPERIENCES IFR
CIGS BY 14-15Z THIS MORNING. CIGS WILL GRADUALLY LIFT AFTER
17-18Z. BY 19-21Z...VFR CONDITIONS SHOULD PREVAIL EVERYWHERE. MVFR
CIGS WILL BEGIN TO SPREAD INTO CWA AGAIN AFTER 06Z POSSIBLY LOWER
NEAR KJBR. KJBR COULD SEE A FEW TSRAS DEVELOP AHEAD OF APPROACHING
COLD FRONT AFTER 09Z. IN ADDITION...WOULD NOT BE SURPRISED TO SEE
A FEW ELEVATED TSRAS DEVELOP NEAR KTUP AFTER 8-9Z DUE TO WAA.
STRONG S WINDS EXPECTED AFTER 15Z. SPEEDS WILL INCREASE TO 12-17
KTS WITH HIGHER GUSTS. SPEEDS WILL DIE DOWN TO 8-10 KTS AFTER
00Z...POSSIBLY LOWER AT KTUP.
KRM
&&
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 75 62 69 43 / 0 30 90 10
MKL 74 58 67 41 / 0 20 90 10
JBR 74 59 65 40 / 10 70 80 0
TUP 74 56 71 47 / 0 0 80 60
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1023 AM PST Mon Dec 3 2012
.SYNOPSIS...
Today`s weather will bring a brief showery break to the persistent
wet weather of late. Most of the showers will be confined to the
Idaho Panhandle...eastern quarter of Washington and near the
cascade crest. a strong and moist storm system will deliver
widespread valley rain and mountain snow to all areas beginning
late tonight and continuing through Tuesday. The snow could be
locally heavy near the cascades and over the highest mountains
elsewhere. The remainder of the week will be cooler and
showery...but no further strong storms are expected through next
weekend.
&&
.DISCUSSION...
Forecast update to decrease POPs and sky cover for today. Morning
satellite imagery showed a pocket of clear skies over the basin.
Best chances for any showers today will be over the mountains,
mainly over the Cascade crest and in the Idaho Panhandle. Radar
has shown showers decreasing in coverage through the late morning
hours. The HRRR model seems to be doing a decent job with the
precipitation and shows these showers continuing to decrease into
this afternoon. We will continue with moist upslope flow into the
Panhandle today, but we will become less unstable as well. Some
isolated snow showers above 4000 feet will continue through the
afternoon across the Central Panhandle Mountains, but any
additional snow accumulations are expected to be light. Web cams
also show roads in the higher terrain of the Central Panhandle
transitioning from snow covered to bare and wet. Due to the
improving conditions, we decided to drop the Winter Storm Waring
for this area. The Winter Storm Watches will continue for the next
system expected to arrive tonight. /SVH
&&
.AVIATION...
18Z TAFS: Some mountain wave clouds will continue to develop
across the region this afternoon. These clouds may produce some
weak showers across the mountains. A shower or two may develop
around the KPUW, KLWS and KCOE taf sites as well, but all other
terminals should remain dry this afternoon. Another moist system
will begin to push into the region this evening. Some weak rain
bands may develop as low level flow begins to back a bit from more
westerly to more southerly. This will result in some light showers
across the region, but the bulk of the moisture is not expected to
arrive until late tonight into early Tuesday morning. Light to
moderate rainfall will be possible with lowering cigs to MVFR
conditions at most taf sites. Best confidence of MVFR cigs will be
at KEAT, KGEG and KCOE. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 45 38 47 37 40 29 / 10 40 100 70 20 10
Coeur d`Alene 46 37 45 36 39 29 / 10 40 100 80 50 30
Pullman 47 39 46 38 41 31 / 20 30 90 100 50 10
Lewiston 53 41 50 41 47 35 / 20 20 80 60 40 10
Colville 45 39 44 37 39 29 / 10 80 100 60 20 20
Sandpoint 43 36 42 35 37 29 / 20 60 100 100 60 50
Kellogg 39 35 40 35 36 31 / 40 60 100 100 80 50
Moses Lake 49 40 52 35 44 29 / 10 60 90 30 10 10
Wenatchee 45 39 45 35 43 29 / 20 70 90 30 10 10
Omak 45 38 42 33 39 27 / 10 90 100 40 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Watch from this evening through Tuesday afternoon
for Northern Panhandle.
WA...Winter Storm Watch from this evening through Tuesday afternoon
for Northeast Mountains-Okanogan Highlands.
Winter Storm Watch from this evening through Tuesday morning for
East Slopes Northern Cascades.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1037 PM MST TUE DEC 4 2012
.UPDATE...
ISSUED AT 923 PM MST TUE DEC 4 2012
LATEST HRRR AND RAP MODEL DATA INDICATE THAT SOME LIGHT SNOW
SHOWERS WILL OCCUR MAINLY BETWEEN 06Z AND 12Z IN UTZ023 AND
COZ004...PARTICULARLY THE ELKHEADS...WHILE THE REST OF THE
NORTHERN MOUNTAINS WILL BE LIMITED TO SOME FLURRIES AT THE
HIGHEST PEAKS. NOT ENOUGH FORCING EVIDENT TO WARRANT A MENTION OF
POPS IN THE FLATTOPS OR OTHER SUBSEQUENT ZONES...SO REMOVED
MENTION OF POPS IN ALL BUT UTZ023 AND COZ004 TONIGHT. THE REST OF
THE FORECAST LOOKS ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 335 PM MST TUE DEC 4 2012
AN UPPER LOW REMAINS OFF THE WEST COAST OF CANADA AND CONTINUES TO
DIRECT A STEADY STREAM OF PACIFIC MOISTURE AND EMBEDDED DISTURBANCES
INLAND. ERN UT/WRN CO WERE BETWEEN WEAK DISTURBANCES THIS AFTERNOON
FOR PARTLY SUNNY SKIES. AN AREA OF MAINLY LIGHT PRECIPITATION
PERSISTED ACROSS PARTS OF NE NV/SRN ID/NW UT THIS AFTERNOON.
CLOUDS WILL THICKEN AGAIN TONIGHT AS THE NEXT WAVE REACHES THE AREA.
WILL CARRY A LOW-END CHANCE OF SNOW FOR THE ERN UINTAS/FLATTOPS/
PARK/ELKHEAD MTNS LATE TONIGHT WITH THE PASSAGE OF THIS NEXT
WAVE...BUT WITH 700 MB FORECAST WARMING ABOVE FREEZING... SNOW
LEVELS WILL BE HIGH. CLOUDS TONIGHT WILL KEEP LOW TEMPS WARMER THAN
LAST NIGHT.
A BETTER CHANCE OF PRECIPITATION ARRIVES WEDNESDAY NIGHT AS A BETTER
DEFINED BUT WEAKENING WAVE APPROACHES. MAY SEE A BIT OF A BREAK
IN CLOUDS LATER WED MORNING BETWEEN DISTURBANCES AGAIN...BUT THEN
CLOUDS INCREASING FROM THE WEST WED AFTERNOON. ISENTROPIC ANALYSIS
REVEALED THE DEEPER RIBBON OF MOISTURE SLIDING OVER NE UT/NW CO WED
EVENING IN NEUTRAL TO WARM ADVECTION FOR AN INCREASING CHANCE OF
PRECIPITATION WED EVENING. 700 MB WINDS REMAIN WEST-SOUTHWEST MOST
OF WED NIGHT AND NOT THE BEST FOR OROGRAPHIC FORCING IN THE MTNS
AROUND STEAMBOAT SPRINGS...BUT ENOUGH MOISTURE AND Q-G FORCING LOOK
PRESENT FOR 1-4 INCHES OF NEW SNOW ACROSS THE NORTHERN CO MTNS
AFTER MIDNIGHT WED NIGHT...WITH A CHANCE OF SNOW IN THE CENTRAL
MTNS. THE EASTERN UINTA MTNS LOOK TO REMAIN SHADOWED BY THE HIGHER
MTNS TO THEIR WEST. A CHANCE OF RAIN OR RAIN/SNOW FOR THE CENTRAL
AND NORTHERN VALLEYS WED NIGHT AS CLOUDS HELP LOW TEMPS STAY ABOVE
NORMAL.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 335 PM MST TUE DEC 4 2012
THE PERSISTENT AREA OF LOW PRESSURE HANGING IN THE NORTHEAST
PACIFIC/GULF OF ALASKA THE PAST FEW WEEKS WILL BE REPLACED BY
RIDGING BEGINNING THURSDAY AND LASTING THROUGH EARLY NEXT WEEK.
THIS PATTERN CHANGE WILL TRANSLATE TO A MORE STORMY PATTERN OVER
THE CENTRAL ROCKIES WITH A MUCH COOLER AIRMASS ARRIVING TO OUR CWA
MID WEEKEND INTO EARLY NEXT WEEK. THERE ARE STILL DETAILS TO BE
WORKED OUT BUT THERE APPEARS TO BE A GOOD CHANCE THAT THE COLORADO
MOUNTAINS WILL BE RECEIVING SOME MUCH NEEDED SNOWFALL AS WINTER
LIKE WEATHER RETURNS AND POSSIBLY LINGERS THROUGH MUCH OF NEXT
WEEK.
THE WEAKENING SYSTEM WED NIGHT INTO THURSDAY STILL HAS A DECENT TAP
TO THE RICH MOISTURE SOURCE CURRENTLY POUNDING THE WEST COAST.
MIXING RATIOS NEAR THE 4G/KG RANGE WILL BE TRANSPORTED INTO
NORTHERN COLORADO PER THETA SURFACES AROUND 300K BY THURSDAY
MORNING. MAXIMIZED LARGE SCALE ASCENT WILL BE CROSSING THE
NORTHERN COLORADO BORDER BY SUNRISE AHEAD OF THE MAIN SHORT WAVE
ENERGY...AND LOOKS TO BE ENHANCED BY A COUPLED JET STRUCTURE.
THEREFORE THE HIGH POPS OVER THE NORTHERN MOUNTAINS EARLY IN THE
DAY LOOK ON TRACK AND ONLY MADE A FEW TWEAKS. LIFT AND SATURATION
THROUGH THE DENDRITIC LAYER WILL DECREASE THROUGH THE DAY BUT WEAK
INSTABILITY AND OROGRAPHICS SHOULD KEEP SOME SHOWERS GOING THROUGH
SUNSET AS THE HIGH COUNTRY LOOKS TO REMAIN MOIST. H7 TEMPS NOT ALL
THAT COLD BEHIND WAVE BUT MAY SEE A FEW SNOW SHOWERS IN THE HIGH
VALLEYS WITH ANOTHER 1-3 INCHES POSSIBLE ON WEST FACING SLOPES OF
HIGHER PEAKS. TEMPERATURES LOOK TO FALL OFF AROUND 5 TO 7 DEGREES.
THURSDAY NIGHT INTO FRIDAY THINGS AGAIN LOOK INTERESTING AS A
VIGOROUS WAVE DIVES OUT OF THE NORTHWEST INTO THE NORTHERN ROCKIES.
MODEL CONSENSUS HOWEVER IS LESS THAN PERFECT WITH NATIONAL GUIDANCE
LEANING TOWARD A MORE DAMPED WAVE PATTERN LIKE THE EURO. NAM SLIDES
CLOSER TO THE THIS SOLN WITH THE GFS DIGGING THE STRONGEST ENERGY
OVER NORTHERN COLORADO BY FRIDAY MORNING. FOR NOW HAVE DECREASING
PRECIPITATION TREND EARLY IN THE OVERNIGHT PERIOD WITH LOSS OF
INSTABILITY AND THE MOISTURE TAP BEING FORCED SOUTHWARD. THEN LIFT
SHOULD INCREASE AFTER MIDNIGHT AS THE WAVE BRUSHES BY TO THE
NORTH AND MOIST WESTERLY FLOW BEGINS OROGRAPHIC SHOWERS IN THE
NORTHERN MOUNTAINS. THE NAM DOES SHOW A SHALLOW FRONT MOVING INTO
THE NORTHWEST ZONES UNDER A WEAK MID LEVEL FRONTO BAND...BUT DEEP
LIFT IS LACKING WITH JET AND MAIN FORCING FARTHER NORTH. GFS HAS
THESE FEATURES COMING TOGETHER FOR THE FAR NORTHERN ZONES AND
PRODUCES SOME BRIEF MODERATE TO HEAVY SNOW. THIS SOLUTION IGNORED
AS AN OUTLIER ATTM BUT SHOULD BE MONITORED FOR TRENDS. SIDING
OUTSIDE THE GFS...DRIER AIR MOVES IN FRIDAY AFTERNOON ALONG WITH
WEAK SUBSIDENCE LEAVING ONLY SOME LIGHT OROGRAPHIC SHOWERS
POSSIBLE IN THE NORTHERN AND CENTRAL MOUNTAINS THAT ARE FAVORED IN
NW FLOW. AFTERNOON TEMPERATURES AGAIN LOOK TO TAKE ANOTHER HIT
AROUND 5 DEGREES.
THE BIG CHANGES COME SATURDAY AS THE MAIN PORTION OF THE REMNANT
PACIFIC LOW DIGS INTO THE GREAT BASIN BY AN AMPLIFYING RIDGE ALONG
THE WEST COAST. THIS ENERGY IN CONJUNCTION WITH THE POLAR VORTEX WILL
SEND A SHOT OF THE COLDEST AIR OF THE SEASON SOUTHWARD AND SPREAD
SNOWFALL ACROSS THE EASTERN UTAH AND WESTERN COLORADO MOUNTAINS.
AGAIN THIS FAR OUT MODEL CONSENSUS IS TIGHTENING NOW THAT THE GFS HAS
FLOPPED BACK TOWARD IT/S 00Z FORECAST...AND NOW CLOSER RESEMBLES
THE EURO...BUT AGAIN IT WILL BE IMPORTANT TO WATCH THESE TRENDS.
FOR NOW LARGE SCALE ASCENT IS MAXIMIZED IN THE SATURDAY MORNING TO
SUNDAY MORNING TIME FRAME WITH THE GFS ON THE EARLY SIDE. THIS
LIFT WILL BE ENHANCED BY THE STRONG COLD FRONT AND POSSIBLY SOME
DECENT POTENTIAL INSTABILITY...DEPENDING ON THE UPPER TROF
LOCATION. THE BIGGEST CONCERN NOW IS MOISTURE AVAILABILITY BUT
THE VERY COLD AIR SHOULD MAKE SNOW PRODUCTION MORE EFFICIENT. FOR
NOW THE OUTLOOK SHOWS SOME CLEARING SUNDAY NIGHT INTO MONDAY AS
THE SYSTEM SHIFT SOUTHEASTWARD. THE TEMPERATURE REGIME WILL BE
WELL BELOW NORMAL SUNDAY INTO EARLY NEXT WEEK WITH ANOTHER SHOT OF
SNOW POSSIBLE MONDAY NIGHT INTO TUESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1033 PM MST TUE DEC 4 2012
VFR CONDITIONS WILL CONTINUE AT ALL TAF SITES THROUGH WEDNESDAY
EVENING UNDER MOIST WESTERLY FLOW ALOFT. CLOUDS WILL LOWER ACROSS
THE NORTH WITH AREAS OF MVFR CIGS AND LOCAL -SN POSSIBLE OVER THE
NORTHERN MTNS BETWEEN THROUGH 15Z WED.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...MDA
SHORT TERM...JAD
LONG TERM...15
AVIATION...JDC
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
923 PM MST TUE DEC 4 2012
.UPDATE...
&&
.SHORT TERM...SFC PRESSURE ACROSS NERN COLORADO CONTINUED TO FALL
SLOWLY THIS EVENING. AS OF 03Z THE DEN-GJT 1500METER PRESSURE
GRADIENT HAD INCREASED TO 6.35 MBS. MODELS CONTINUE THIS TREND
THE NEXT FEW HRS BEFORE REVERSING AFTER MIDNIGHT AS RADIATIONAL
COOLING ON THE PLAINS LEADS TO RISING PRESSURES. RUC AND NAM CROSS
SECTIONS SHOW A GRADUAL INCREASE IN THE WESTERLY WIND COMPONENT
AT MTN TOP LEVEL THROUGH THE NIGHT...PEAKING AROUND 35KT AS OF
12Z/WED. MAY SEE WEST WINDS GUSTING 35-40 MPH ON THE RIDGETOPS
AND CANYONS OF THE FRONT RANGE...AND 25-35 MPH OCCASIONALLY NEAR
THE BASE OF THE FOOTHILLS IN NORTHERN JEFFERSON...BOULDER...
LARIMER COUNTIES. OTHERWISE MID AND HIGH LEVEL MOISTURE PASSING
THROUGH THE MTN WAVE WILL ALSO PRODUCE PERIODS OF MTN WAVE CLOUDS
OVER AND ALONG THE FRONT RANGE. THE DOWNSLOPE BREEZES AND THE
CLOUD COVER WILL HELP TO HOLD MIN TEMPS UP ALONG THE BASE OF THE
FOOTHILLS.
.AVIATION...VFR CONDITIONS AND LIGHT DRAINAGE WINDS UNDER 12KTS
EXPECTED AT DENVER AREA AIRPORTS OVERNIGHT. WILL ALSO SEE OF
PERIODS OF MID AND HIGH MTN WAVE CLOUDINESS OVER THE METRO AREA
THROUGH THE NIGHT. BJC NEAR THE BASE OF THE FOOTHILLS COULD SEE
WEST WINDS GUSTING OCCASIONALLY 25-35 MPH.
&&
.PREV DISCUSSION... /ISSUED 350 PM MST TUE DEC 4 2012/
SHORT TERM...MODERATE WEST TO NORTHWEST FLOW ALOFT ACROSS REGION
WITH SHORT WAVE RIDGE OVER GREAT BASIN. WEAK STABLE LAYER
CURRENTLY AT MOUNTAIN TOP WITH RADAR SHOWING SOME SIGNS OF A
MOUNTAIN WAVE. WINDS ALOFT NOT VERY STRONG WITH CROSS MOUNTAIN
FLOW 30-35 KTS AT MOUNTAIN TOP. SOME RECENT GUSTS TO 40 MPH BEING
REPORTED IN THE ESTES PARK AREA...BUT APPEAR LOCALIZED AND PERHAPS
TERRAIN DRIVEN. LATEST RUC CROSS SECTIONS INDICATE WINDS ALOFT
GRADUALLY DECREASING AFTER 02Z WITH CROSS MOUNTAIN WINDS AROUND 25
KTS NEAR RIDGE TOP AND ALONG HIGHER FOOTHILLS BY 06Z. THUS SHOULD
SEE WIND GUSTS GRADUALLY DECREASE DURING THE EVENING THOUGH THE
TERRAIN MAY KEEP THINGS A BIT GUSTY. SHOULD ALSO SEE A GRADUAL
INCREASE IN HUMIDITY AS TEMPERATURES COOL. LATEST SATELLITE LOOPS
SHOW CLOUDS HAVE THINNED ACROSS THE AREA WITH REMNANTS OF WAVE
CLOUD EAST OF URBAN CORRIDOR. MORE MOISTURE UPSTREAM...WITH
INCREASING HIGH LEVEL MOISTURE OVERNIGHT. WRF SYNTHETIC SATELLITE
IMAGERY SUGGESTING THE WAVE CLOUD REDEVELOPS ALONG FOOTHILLS AFTER
08Z. ON WEDNESDAY...FLOW ALOFT BECOMES WESTERLY AS RIDGE MOVES
SOUTH AND EAST OF COLORADO. CROSS SECTIONS SHOW MOISTURE
INCREASING ACROSS THE AREA WITH SOME LOWERING OF THE MOISTURE
ACROSS MOUNTAINS DURING THE MORNING...MAINLY NORTH OF INTERSTATE
70. MAY BE ENOUGH OROGRAPHICS TO GENERATE SOME SHOWERS ACROSS ZONE
31. OTHERWISE WINDS ALOFT TO INCREASE WITH CROSS MOUNTAIN FLOW AROUND
40 KTS AT MOUNTAIN TOP BY 18Z. THUS WINDS TO BE GUSTY ACROSS THE
MOUNTAINS AND HIGHER FOOTHILLS WITH LOCAL GUSTS AROUND 45 MPH
POSSIBLE DURING THE AFTERNOON. THE GUSTY WINDS WILL KEEP THE FIRE
DANGER ELEVATED ALONG THE FOOTHILLS...BUT HUMIDITY SHOULD REMAIN
ABOVE CRITICAL FIRE WEATHER THRESHOLDS. TEMPERATURE AND THICKNESS
PROGS AS WELL AS GUIDANCE SHOWING HIGHS IN THE 60S ACROSS THE
PLAINS. THIS LOOKING REASONABLE. CURRENT TEMPERATURE GRIDS IN LINE
WITH GUIDANCE...ONLY MINOR CHANGES NEEDED.
LONG TERM...WESTERLY FLOW ALOFT WILL PREVAIL WEDNESDAY NIGHT AND
THURSDAY. WINDS WILL INCREASE WEDNESDAY NIGHT OVER THE MOUNTAINS AND
FOOTHILLS AS A COLD FRONT MOVES THROUGH THE STATE. A WEAK SHORT
WAVE TROUGH MAY BRING LIGHT SNOW TO THE MOUNTAINS AND PERHAPS SOME
LIGHT RAIN OVER EASTERN COLORADO THURSDAY.
THE WESTERLY JET WILL SINK SOUTH AS AN UPPER LEVEL TROUGH MOVES ONTO
THE PACIFIC NORTHWEST COAST. THIS WILL BRING COOLER CONDITIONS ON
FRIDAY WITH HIGHS IN THE 40S. ANOTHER WEAK DISTURBANCE EMBEDDED IN
THE FLOW ALOFT WILL BRING ANOTHER CHANCE FOR LIGHT PRECIPITATION.
THE UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST WILL DIVE SOUTH
ACROSS THE GREAT BASIN SATURDAY AND END UP OVER THE SOUTHERN ROCKIES
SUNDAY. THIS WILL PUSH A STRONG COLD FRONT ACROSS COLORADO. STILL
SOME DIFFERENCE ON TRACK AND TIMING...BUT WILL BE ENOUGH ENERGY TO
BRING A PERIOD OF SNOW TO THE AREA. BIGGEST QUESTIONS ARE WHEN AND
HOW MUCH. APPEARS THE SNOW WILL BEGIN SOMETIME SATURDAY AND COME TO
AN END EARLY SUNDAY. MAY SEE SOME HEAVIER SNOW BANDS SATURDAY AS THE
JEST SINKS SOUTH ACROSS COLORADO. WILL CENTER THE HIGHEST POPS
AROUND SATURDAY NIGHT WHEN THE BEST CHANCE WILL BE ACCORDING TO THE
MODELS. COLD AIR WILL MOVE IN WITH THIS SYSTEM AND HIGHS WILL LIKELY
REMAIN BELOW FREEZING SUNDAY AND EARLY NEXT WEEK. NORTHWEST FLOW MAY
BRING LIGHT OROGRAPHIC SNOW EARLY NEXT WEEK...OTHERWISE JUST DRY AND
COOL CONDITIONS ARE EXPECTED FOR MONDAY AND TUESDAY.
AVIATION...LIGHT EASTERLY WINDS AT APA AND DEN TO WEAK AND BECOME
SOUTHERLY AS DRAINAGE PATTERN DEVELOPS. WINDS TO REMAIN WESTERLY
AT BJC. ON WEDNESDAY...WINDS TO BECOME NORTHWEST AFTER 18Z WITH
SPEEDS AROUND 8 KTS. HIGH LEVEL MOISTURE TO INCREASE AFTER 06Z
WITH THE POTENTIAL FOR A WAVE CLOUD ALONG FOOTHILLS BY 10Z. VFR TO
CONTINUE WITH CEILINGS UNLIMITED.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BAKER/D_L
LONG TERM....MEIER
AVIATION...BAKER/D_L
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
335 AM EST WED DEC 5 2012
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOW A NORTHERN STREAM TROUGH
FRACTURE UNDERWAY ACROSS THE MIDDLE/SOUTHERN MS VALLEY EARLY THIS
MORNING. RESULTING DETACHED SHORTWAVE ON THE SOUTHERN PORTION OF THE
ORIGINAL TROUGH IS SLOWING TRANSLATING EAST AND SOUTHEASTWARD OVER
THE NORTHERN GULF OF MEXICO. UPPER LEVEL RIDGE THAT HAS BEEN
DOMINANT IN OUR WEATHER THE PAST SEVERAL DAYS IS STILL OVERHEAD...
BUT WILL BE REPLACED RAPIDLY DURING THE NEXT 6-12 HOURS BY
INCREASING CYCLONIC FLOW AHEAD OF THE SHORTWAVE. 05/00Z KTBW
SOUNDING PROFILE STILL SHOWED THE RIDGE INFLUENCE IN THE FORM OF A
WELL-DEFINED SUBSIDENCE INVERSION JUST ABOVE 800MB. WOULD EXPECT
THAT THIS LARGE SCALE SUBSIDENCE IS ALREADY WEAKENING OVER OUR HEADS
THIS MORNING...AND WILL BEGIN TO SEE A NEW PROFILE EMERGE WITH THE
12Z SOUNDING.
AT THE SURFACE...RIDGE OF HIGH PRESSURE CONTINUES TO EXTEND FROM
OFF THE SOUTHEAST COAST BACK TO SOUTHERN GA...BUT IS BEGINNING TO
WEAKEN AND BECOME LESS DEFINED IN RESPONSE TO THE APPROACH OF A
SURFACE COLD FRONT MOVING OUT OF THE TN VALLEY. ALTHOUGH THE RIDGE
IS WEAKENING...GRADIENT FLOW SOUTH OF THE AXIS CONTINUES TO PROVIDE
THE REGION WITH A LIGHT EASTERLY BOUNDARY LAYER WIND AND ABUNDANT
LOW LEVEL ATLANTIC MOISTURE. SKIES THIS MORNING ARE GENERALLY PARTLY
CLOUDY WITH AREAS OF 4-6KFT STRATOCU MOVING ACROSS THE PENINSULA
WITHIN LOW LEVEL FLOW.
&&
.SHORT TERM (TODAY - FRIDAY)...
TODAY...LARGE SCALE MID/UPPER LEVEL FLOW WILL BECOME INCREASINGLY
CYCLONIC IN NATURE THROUGH THE DAY WITH RESULTING WEAK SYNOPTIC
SUPPORT ALLOWING FOR ISOLATED/WIDELY SCT LIGHT SHOWER/SPRINKLE
DEVELOPMENT. OVERALL COLUMN MOISTURE WILL STILL NOT BE ALL THAT
IMPRESSIVE...BUT ENOUGH INGREDIENTS COMING TOGETHER TO SUPPORT A
SLIGHT CHANCE 20-30% CHANCE OF SHOWERS. THIS SOLUTION IS SHOWN BY
THE HI-RES CONVECTIVE ALLOWING GUIDANCE SUITE...AND SEE LITTLE
REASON TO ARGUE WITH THE CONSENSUS. BEST CHANCES FOR SHOWERS WILL
LIKELY BE ACROSS THE EASTERN HALF OF THE FORECAST AREA DURING THE
AFTERNOON ASSOCIATED WITH ACTIVITY MOVING INLAND FROM THE EAST
COAST. THE IMPACT OF ANY SHOWERS SHOULD BE MINIMAL...WITH VERY
LITTLE IN THE WAY OF RAINFALL ACCUMULATION FOR THOSE SPOTS THAT DO
SEE A BRIEF SHOWER. MORE IN THE WAY OF CLOUDS TODAY COMPARED TO
PREVIOUS DAYS...HOWEVER STILL EXPECT ENOUGH SUNNY BREAKS TO ALLOW
TEMPERATURES TO REACH WELL UP INTO THE 70S...AND PERHAPS NEAR 80 AT
WARMER LOCATIONS.
TONIGHT/THURSDAY...SHORTWAVE AXIS MOVES OVER THE EASTERN GULF OF
MEXICO OVERNIGHT AND THEN APPROACHES THE FL PENINSULA THURSDAY
MORNING. GFS/ECMWF SHOWING THE BEST ASSOCIATED QG FORCING/SYNOPTIC
SUPPORT COINCIDENT WITH DEEP LAYER MOISTURE COMING TOGETHER OVER THE
SOUTHERN HALF OF THE FL PENINSULA. WITH THIS IN MIND WILL KEEP THE
BEST SHOWER CHANCES (30-40%) TO THE SOUTH OF TAMPA BAY THROUGH THE
MORNING HOURS. AS THIS LARGE SCALE FORCING BEGINS TO PIVOT EASTWARD
LATER IN THE DAY...IT SHOULD FURTHER AID THE DEVELOPMENT OF SHOWERS
MOVING INLAND FROM THE EAST COAST. SOUTHERN AND EASTERN ZONES WILL
SHOW 30-40% POPS FOR THE AFTERNOON WITH 20% ISOLATED SHOWER CHANCES
FOR TAMPA BAY AND THE NATURE COAST ZONES. ONCE AGAIN...RAINFALL
AMOUNTS WILL GENERALLY BE LOW WITH ANY SHOWERS AND A DROUGHT BUSTER
THIS EVENT WILL NOT BE.
FRIDAY...SHORTWAVE ENERGY SHEARS OUT AND EXITS TO OUR EAST EARLY IN
THE DAY. THE MOVEMENT OF THIS ENERGY OVER THE GULF STREAM THURSDAY
NIGHT SHOULD ENHANCE THE DEVELOPMENT OF AN INVERTED SURFACE TROUGH
ALONG THE FL EAST COAST. HIGH PRESSURE WILL BE BUILDING TO OUR NORTH
BACK DOWN THE EASTERN SEABOARD DURING THIS TIME. INCREASING EASTERLY
LOW LEVEL FLOW SHOULD THEN HELP PUSH THIS SURFACE TROUGH SLOWLY BACK
TO THE WEST THROUGH THE DAY. SO...DESPITE THE LARGE SCALE SUBSIDENCE
OVERSPREADING THE REGION IN THE WAKE OF THE SHORTWAVE...THE LOW
LEVEL FOCUS ALONG THE INVERTED TROUGH AND INCREASING EASTERLY FLOW
SHOULD PROMOTE FURTHER SHALLOW SHOWER DEVELOPMENT ALONG THE FL EAST
COAST. AFTER A BREAK EARLY FRIDAY...WILL BRING ISOLATED SHOWER
MENTION ALONG THE WEST COAST AND SCT SHOWERS INLAND BACK INTO THE
FORECAST BY FRIDAY AFTERNOON.
&&
.LONG TERM (SATURDAY - NEXT TUESDAY)...
NO MAJOR PROBLEMS THROUGH THE WEEKEND AS SURFACE RIDGING CONTINUES
FROM THE ATLANTIC WESTWARD TO FLORIDA WHILE UPPER-LEVEL ENERGY
REMAINS TO OUR WEST. THERE WILL BE A FEW SHOWERS AROUND BOTH DAYS AS
A MOIST LOW-LEVEL SOUTHEASTERLY FLOW MOVES ACROSS THE HEATED
SURFACE. THE TRICKY PART OF THE FORECAST COMES DURING THE
MONDAY/TUESDAY TIMEFRAME WHEN MODELS START TO DISAGREE ON AN
APPROACHING UPPER-LEVEL TROUGH.
THE MODELS AS A WHOLE HAVE TRENDED A LITTLE FASTER/MORE PROGRESSIVE
WITH THE TROUGH WHICH RESULTS IN A FRONTAL PASSAGE LATE MONDAY OR ON
TUESDAY. THE GFS IS THE FASTER OF THE MODELS AND HAS THE FRONT
APPROACHING THE TAMPA BAY AREA MONDAY EVENING. THE EARLIER 12Z ECMWF
WAS MUCH SLOWER...BUT THE MORE RECENT 00Z RUN HAS SPLIT THE
DIFFERENCE NOW WITH THE FRONT REACHING TAMPA BAY TUESDAY MORNING.
THE 12 HOUR DIFFERENCE IN TIMING WILL RESULT IN SIGNIFICANT
DIFFERENCES IN WHEN THE BEST RAIN CHANCES WILL BE AND WHEN THE
COOLER AIR MOVES IN. HAVE LEANED MOST HEAVILY ON THE 00Z ECMWF BUT
DID BLEND THE GFS/MEX TEMPERATURES IN WHICH WERE COOLER THAN THE
ECMWF. HIGHEST RAIN CHANCES SHOULD BE CENTERED ON MONDAY NIGHT...
BUT THINK WE WILL SEE SOME SHOWERS AHEAD OF THE FRONT MONDAY.
SHOWERS SHOULD BEGIN TO TAPER OFF FROM NORTH TO SOUTH...AT LEAST
INITIALLY...BEHIND THE FRONT ON TUESDAY.
BOTH MODELS RAPIDLY HALT THE SOUTHWARD PROGRESSION OF THE FRONT
BEYOND DAY 7 AND SHOW THE POTENTIAL FOR SOME OVER-RUNNING RAINS FOR
THE MIDDLE TO END OF NEXT WEEK.
&&
.AVIATION...
MAINLY VFR NEXT 24 HOURS. SLIGHT CHANCE OF SOME EARLY MORNING PATCHY
FOG MAINLY NEAR PGD AND LAL BUT CONFIDENCE TOO LOW TO INCLUDE IN
TAFS AT THIS TIME.
&&
.MARINE...
HIGH PRESSURE TO THE NORTH OF THE REGION WILL WEAKEN TODAY AND
THURSDAY HELPING TO KEEP WINDS AND SEAS BELOW HEADLINE CRITERIA THE
NEXT SEVERAL DAYS. HIGH PRESSURE WILL ONCE AGAIN BUILD TO OUR NORTH
DURING THE UPCOMING WEEKEND...BUT SHOULD NOT BE STRONG ENOUGH TO
RESULT IN ANY SIGNIFICANT MARINE CONCERNS. THE NEXT COLD FRONT IS
ANTICIPATED TO ARRIVE OVER THE EASTERN GULF OF MEXICO DURING THE
EARLY PORTION OF NEXT WEEK.
&&
.FIRE WEATHER...
NO SIGNIFICANT FIRE WEATHER CONCERNS ARE ANTICIPATED THROUGH THE
REMAINDER OF THE WEEK. A GENERAL EASTERLY FLOW WILL CONTINUE TO
TRANSPORT ATLANTIC MOISTURE INTO THE REGION AND PREVENT CRITICAL
LEVELS OF RELATIVE HUMIDITY. ISOLATED TO WIDELY SCATTERED SHOWERS
WILL BE IN THE FORECAST THE NEXT SEVERAL DAYS...HOWEVER NO
SIGNIFICANT RAINFALL ACCUMULATIONS ARE EXPECTED.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 79 60 79 60 / 20 10 20 10
FMY 80 59 80 60 / 20 20 30 10
GIF 79 56 80 57 / 20 20 30 20
SRQ 78 59 79 61 / 10 10 20 10
BKV 79 55 80 55 / 20 10 20 10
SPG 77 63 77 62 / 10 10 20 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS JACKSON KY
1247 AM EST WED DEC 5 2012
.UPDATE...
ISSUED AT 1247 AM EST WED DEC 5 2012
UPDATED THE FORECAST TO BETTER TIME THE SYSTEM THROUGH THE AREA. WHEN
THE FRONT MOVES THROUGH...THERE HAS BE ABOUT A 2 HOUR PERIOD OF WIND
GUSTS GREATER THAN 20 MPH. THE FRONT SHOULD CONTINUE MOVING TO THE SE
AND WILL BE MOVE INTO VA AND TN BETWEEN BY 1:30 AM. THERE
PRECIPITATION EXTENDS ABOUT 80 MILES NORTHWEST OF THE FRONT...SO RAIN
SHOULD CONTINUE A FEW HOURS AFTER THE FRONT HAS PASSED. HAVE A LITTLE
CONCERN THAT THE CLOUDS MAY HANG IN LONGER DUE TO THE FLOW BECOMING
MORE NORTHEASTERLY BEHIND THE FRONT.
UPDATE ISSUED AT 1050 PM EST TUE DEC 4 2012
RAIN HAS FILLED BACK IN ALONG THE FRONT AND WILL ONLY NEED TO FINE
TUNE THE TIMING OF THE BACK EDGE TO THE PRECIP IN OUR HOURLY GRIDDED
DATABASE AS MAJORITY OF THE FORECAST IS ON TRACK TONIGHT. IT DOES
APPEAR BASED ON RADAR TRENDS THAT THE FRONT IS HANGING UP A BIT MORE
THAN EARLIER THOUGHT SO WILL PROLONG A SLIGHT CHANCE OF SHOWERS INTO
TOMORROW MORNING FOR OUR VA AND TN BORDER COUNTIES. OTHERWISE...NO
SUBSTANTIVE CHANGES ARE NEEDED. HAVE A GOOD NIGHT...
UPDATE ISSUED AT 823 PM EST TUE DEC 4 2012
THE COLD FRONT HAS NOW PASSED INTO OUR NORTHWEST COUNTIES HOWEVER
THE SOLID MASS OF RAINFALL THAT WAS ACCOMPANYING THE FRONT EARLIER
HAS WITHERED SUBSTANTIALLY AS IT HAS ENTERED EAST KENTUCKY. THERE IS
STILL ENOUGH PRECIP RIGHT ALONG THE FRONT TO JUSTIFY 100 POPS BUT
FORECAST QPF HAS BEEN REDUCED TO A QUARTER INCH OR LESS FOR MOST
LOCATIONS. TEMPS WILL REMAIN IN THE 60S UNTIL THE FRONT PASSES AND
THEN DROP QUICKLY THROUGH THE 50S. OUR HOURLY TEMP DATA WAS MASSAGED
USING THE RUC13 TIMING BUT THIS WILL NOT ALTER OUR MIN TEMP FORECAST
FOR NOW.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 255 PM EST TUE DEC 4 2012
SURFACE COLD FRONT IS CURRENTLY ALIGNED FROM NORTHWEST OHIO DOWN
THROUGH WESTERN KENTUCKY AND TENNESSEE. THE MAIN BAND OF
PRECIPITATION ASSOCIATED WITH THIS BOUNDARY IS STILL A FEW HOURS
AWAY...WITH MOST OF THIS ACTIVITY WORKING THROUGH IN THE 7 PM TO 12AM
TIME FRAME...AND THEN LINGERING A BIT LONGER IN THE SOUTHEAST AS THE
BOUNDARY SLOWS DOWN ALONG THE TERRAIN. EVERYONE WILL MEASURE OUT OF
THIS...SO SEE NO REASON TO NOT MAINTAIN NEAR 100 POPS. THERE HAS BEEN
SOME LIGHTNING ACTIVITY EMBEDDED WITHIN THE LINE...HOWEVER EXPECT
THESE TO WEAKEN AS IT COMES THROUGH EASTERN KENTUCKY...SO WILL LEAVE
OUT THE MENTION.
HIGH PRESSURE TRAVERSING THE GREAT LAKES AND OHIO VALLEY WILL THEN
PROVIDE DRY WEATHER ACROSS THE AREA FOR WEDNESDAY AND WEDNESDAY
NIGHT. TEMPERATURES WILL BE COOLER THAN WE HAVE BEEN SEEING
LATELY...BUT WILL STILL AVERAGE ABOVE NORMAL...WITH HIGHS GENERALLY
IN THE MID TO UPPER 50S...WITH A FEW LOWER 60S SOUTH ON WEDNESDAY.
LOWS WEDNESDAY NIGHT WILL DROP DOWN TO BELOW 30 IN SOME OF THE MORE
SHELTERED VALLEYS ALONG AND NORTH OF THE MOUNTAIN PARKWAY.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 255 PM EST TUE DEC 4 2012
MODEL PATTERN BEGINS ON THU MORNING WITH A WEAK 50H RIDGE OVER THE
NRN APPALACHIAN MTS AND NEARLY ZONAL FLOW FROM THE PLAINS TO THE
OHIO VALLEY. A WEAK AREA OF LOW PRESSURE OVER THE ERN GULF IS THE
IMPETUS FOR A FEW RETURN FLOW SHOWERS IN THE TENN VALLEY AROUND THE
BACK SIDE OF THE SFC HIGH OVER ERN PA/NY. WEATHER SHOULD REMAIN DRY
AND WARM ALTHOUGH A FEW SPRINKLES COULD BE FOUND LATE THU. BY FRI...
AN AREA OF LOW PRESSURE...ACCOMPANIED BY A LEE SIDE TROUGH...WILL
FORM IN THE SRN PLAINS. THE SFC HIGH WILL HAVE MOVED TO THE ATLANTIC
AND A WARM FRONT WILL BEGIN FORMING FROM OK TO PA. LIFT OVER THE
WARM FRONT FROM THE PREVAILING SOUTHERLY WIND WILL CAUSE A BETTER
CHANCE OF PCPN TO FORM OVER THE OHIO RIVER WITH A GOOD CHANCE OF
RAIN OVER OUR NRN COUNTIES. WAVES ALONG THE FRONTAL BOUNDARY WILL
ENHANCE THE CHANCE FOR PCPN THRU THE REMINDER OF THE EXTENDED FCST.
TIMING OF EACH WAVE WILL BE THE DETERMINING FACTOR FOR TIMING OF
PCPN AND THERE IS LITTLE CONFIDENCE WITH THE FAST FLOW FOR PLACEMENT
OF PCPN IN THIS FCST. HAVE WORKED WITH THE 00Z ECMWF TO TRY TO TIME
PCPN INTO THE REGION AS THE ECMWF HAS BEEN FAIRLY CONSISTENT WITH
RUN TO RUN DETAILS. NEXT MAJOR FRONTAL PASSAGE WILL OCCUR TUE BUT
TIMING IS IN QUESTION EVEN HERE WITH THE ECMWF ABOUT 6 HOURS FASTER
THAN THE GFS AND MUCH CLEANER WITH THE PASSAGE AS THE PARENT LOW IS
FARTHER NORTH AND WEST OF THE GFS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1247 AM EST WED DEC 5 2012
THE FRONT SHOULD CONTINUE MOVING TO THE SE AND WILL BE MOVE INTO VA
AND TN BETWEEN BY 1:30 AM. THERE PRECIPITATION EXTENDS ABOUT 80
MILES NORTHWEST OF THE FRONT...SO RAIN SHOULD CONTINUE A FEW HOURS
AFTER THE FRONT HAS PASSED. HAVE A LITTLE CONCERN THAT THE CLOUDS
MAY HANG IN LONGER DUE TO THE FLOW BECOMING MORE NORTHEASTERLY
BEHIND THE FRONT. SKIES WILL CLEAR QUICKLY BY OR SHORTLY AFTER DAWN
AT THE TAF SITES WITH A LIGHT NORTHEAST WIND FORECAST THROUGH THE DAY
ON WEDNESDAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JJ
SHORT TERM...GEOGERIAN
LONG TERM....DUSTY
AVIATION...JJ
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
332 AM EST WED DEC 5 2012
.SYNOPSIS...
ISSUED AT 332 AM EST WED DEC 5 2012
HIGH PRESSURE OVER MICHIGAN WILL MEAN PARTLY CLOUDY SKIES TODAY.
HIGH TEMPERATURES IN THE MID TO UPPER 30S WILL SLOWLY RISE TO THE
LOWER 40S THURSDAY AS THE HIGH SLIPS EAST AND WARMER AIR RETURNS TO
THE AREA. MIXED RAIN AND SNOW ARE POSSIBLE OVER THE WEEKEND AS A
STORM SYSTEM MOVES NORTHEAST TOWARD THE GREAT LAKES.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 332 AM EST WED DEC 5 2012
FORECAST CONCERNS DEAL WITH PCPN TRENDS THURSDAY NIGHT AND FRIDAY.
THE CORE OF THE COLD AIR MOVING OVER LOWER MICHIGAN AND CAUSING SOME
STRATOCU WILL DRIFT EAST TODAY LEADING TO PT CLDY SKIES. THE NEXT
WEATHER SYSTEM WILL BE THE APPROACH OF BOTH A COLD FRONT AND A WAVE
OF LOW PRESSURE THURSDAY NIGHT. ISENTROPIC LIFT NEAR THE FRONTAL
BOUNDARY LEADS TO LOW CONDENSATION PRESSURE DEFICITS AND RAIN
THURSDAY NIGHT ACROSS THE CWA. APPROACHING LOW PRESSURE FROM THE SRN
PLAINS WILL ALSO DRAW SOME MOISTURE NWD. AS THE WAVES MOVES BY
FRIDAY...SOME COLDER AIR WILL WORK INTO THE SYSTEM RESULTING IN
MIXED RAIN AND SNOW OVER THE NRN CWA.
.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 332 AM EST WED DEC 5 2012
WE WILL MAINTAIN LOW POPS FOR SOME MIXED LIGHT RAIN AND LIGHT SNOW
SHOWERS FRIDAY NIGHT THROUGH SATURDAY. THIS WITH A NEARLY STATIONARY
BOUNDARY DRAPED ACROSS THE LWR OH VALLEY REGION AND SOME LIGHT
OVERRUNNING PCPN EXPECTED WELL TO THE NORTH OF THAT BOUNDARY INTO
SOUTHERN LWR MI.
THE FCST FOR LATE IN THE WEEKEND INTO EARLY NEXT WEEK IS COMPLICATED
DUE TO MEDIUM RANGE GUIDANCE DISCREPANCIES AND LACK OF RUN TO RUN
CONSISTENCY. WE WILL LEAN TOWARD THE 00Z ECMWF WHICH SUGGESTS THAT
THE BOUNDARY WILL LIFT NORTHWARD WITH A LOW PRESSURE WAVE SUNDAY
CAUSING PCPN TO CHANGE TO MAINLY PLAIN RAIN SHOWERS.
THE UPPER LEVEL PATTERN WILL BECOME MORE AMPLIFIED SUNDAY INTO EARLY
NEXT WEEK AS AN UPPER LEVEL TROUGH DEEPENS OVER THE PLAINS STATES
AND SHIFTS EAST INTO OUR REGION TOWARD TUESDAY. THIS PATTERN COULD
BE CONDUCIVE TO CYCLOGENESIS OVER THE ARKLATEX REGION SATURDAY
NIGHT/SUNDAY AND THAT LOW PRESSURE SYSTEM WILL TRACK NORTHEASTWARD.
00Z GFS GUIDANCE SUGGESTS THIS SYSTEM COULD BRING SOME ACCUMULATING
SNOW INTO PORTIONS OF LWR MI AS EARLY AS LATE SUNDAY AND MAINLY FOR
MONDAY AND TUESDAY. HOWEVER IT IS NOTED THAT THE 00Z ECMWF ONLY
SHOWS A FAIRLY WEAK LOW TRACKING NE THRU OUR REGION SUNDAY NIGHT
(MUCH FASTER THAN THE 12Z EC) AND DOES NOT SHOW NEARLY AS MUCH
POTENTIAL FOR ACCUMULATING SNOW EARLY NEXT WEEK.
TEMPS WILL AVERAGE A LITTLE ABOVE NORMAL FRIDAY NIGHT THROUGH SUNDAY
BEFORE RETURNING TO NEAR TO EVEN POTENTIALLY A LITTLE BELOW NORMAL
FOR EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1144 PM EST TUE DEC 4 2012
LITTLE CHANGE IN THINKING FROM THE PREVIOUS FORECAST. THE AREA OF
LOW CLOUDS IS TRYING TO MOVE SOUTH BUT SEEMS TO BE STRUGGLING TO
GET SOUTH OF ROUTE 10...WHICH IS WHAT THE NAM12 IS SUGGESTING
WOULD HAPPEN (THROUGH 06Z). THE RAP MODEL BRING THE LOW CLOUDS
FARTHER SOUTH BUT STILL ONLY BRINGS THEM TO I-96 FOR THE MOST
PART. SO I DID NOT CHANGE MY OVERALL TAF SITE FORECAST... BRINGING
MVFR CIGS MKG...GRR AND LAN AND KEEPING AZO...BTL AND JXN CLEAR
THROUGH WEDNESDAY.
&&
.MARINE...
ISSUED AT 332 AM EST WED DEC 5 2012
THE SCA REMAINS IN EFFECT THROUGH THIS AFTERNOON. WAVES WILL
GRADUALLY DECREASE THROUGHOUT THE DAY. HOWEVER...A SCA MAY BE NEEDED
AGAIN TONIGHT AS WINDS INCREASE AHEAD OF THE NEXT COLD FRONT.
&&
.HYDROLOGY...
ISSUED AT 332 AM EST WED DEC 5 2012
NO HYDRO ISSUES EXPECTED.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
LMZ844>849.
&&
$$
SYNOPSIS...93
SHORT TERM...93
LONG TERM...LAURENS
AVIATION...WDM
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1144 PM EST TUE DEC 4 2012
.SYNOPSIS...
ISSUED AT 335 PM EST TUE DEC 4 2012
COLD AIR WILL SETTLE OVER THE REGION TONIGHT BEHIND A COLD FRONT
EXITING TO THE SOUTHEAST. OVERNIGHT LOWS WILL FALL INTO THE 20S...
WHICH IS ABOUT 20 DEGREES COLDER THAN LAST NIGHTS LOWS. HIGH
PRESSURE WILL PROVIDE DRY WEATHER FOR WEDNESDAY AND THURSDAY BEFORE
ANOTHER CHANCE OF LIGHT RAIN OR MIXED LIGHT RAIN AND SNOW RETURNS
FOR THE END OF WEEK.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 335 PM EST TUE DEC 4 2012
CLEARING CONTINUES TO ADVANCE EAST THIS AFTERNOON AND MUCH DRIER AIR
WITH DEW POINTS IN THE 20S/TEENS IS NOTED UPSTREAM. THIS SETS THE
STAGE FOR A COLD NIGHT...BUT THE NW FLOW COLD ADVECTION MAY ALSO
GENERATE SOME LAKE EFFECT STRATUS LATER TONIGHT WHEN H8 TEMPS AROUND
-10C ARRIVE FROM THE NORTH.
THE CHANCE FOR SNOW SHOWERS WITH THESE CLOUDS IS QUITE LOW DUE TO
VERY SHALLOW MOISTURE DEPTH... BUT WILL CARRY A FEW FLURRIES IN THE
FAR NRN CWFA. THE BUFKIT PROFILE AT CADILLAC DOES SHOW ICE
NUCLEATION
AT THE TOP OF THE CLOUDS AFTER MIDNIGHT... BUT ELSEWHERE IN THE CWFA
THERE IS NO NUCLEATION PRESENT. ITS ALSO QUESTIONABLE IF THE CLOUDS
WILL MAKE IT MUCH FARTHER SOUTH THAN ABOUT I-96.
WHATEVER LAKE CLOUDS/FLURRIES ARE PRESENT ON WEDNESDAY MORNING
SHOULD DIMINISH IN THE AFTERNOON AS THE SFC HIGH BUILDS IN AND THE
LOW LEVEL WINDS BECOME NORTHEASTERLY/ANTICYCLONIC.
ISENTROPIC LIFT DEVELOPS ON THURSDAY NIGHT WHICH MAY RESULT IN SOME
LIGHT RAIN BREAKING OUT AS CONDENSATION PRESSURE DEFICITS GRADUALLY
LOWER.
.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 335 PM EST TUE DEC 4 2012
UPPER PATTERN IS FORECAST TO TRANSITION FROM A ZONAL FLOW TO AN
UPPER TROUGH AS WE MOVE THROUGH THE PERIOD. THE DETAILS OF THE
EVOLUTION THOUGH REMAIN DIFFICULT TO DISCERN AS THERE ARE
DISCREPANCIES BETWEEN THE ECWMF AND THE GFS. BY EARLY NEXT WEEK
TROUGHING IS FORECAST TO STRETCH THROUGH THE PLAINS STATES WITH
LOWER MICHIGAN ON THE DOWNSTREAM SIDE OF THE TROUGH IN A LOCATION
WHERE SYSTEM EJECTING FROM THE LONGWAVE TROUGH WILL MOVE THROUGH.
THE TIMING AND TRAJECTORY OF THESE SYSTEMS ARE WHERE FORECAST
PROBLEMS DEVELOP.
IN GENERAL TRIED TO TREND THE FORECAST TOWARD THE ECMWF GIVEN ITS
BETTER PERFORMANCE IN THE LONG RANGE. OVERALL THOUGH DID NOT MAKE
SIGNIFICANT CHANGES GIVEN MODEL DISPARITY.
FRIDAY INTO SATURDAY THE GFS LIFTS A LOW ALONG A BOUNDARY THROUGH
THE GREAT LAKES REGION...WHILE THE ECMWF DOES NOT GENERATE A LOW
KEEPING A BOUNDARY IN THE OHIO VALLEY. HAVE CHANCE POPS FOR RAIN AND
SNOW GIVEN THE FACT THAT WE WILL BE NEAR THE TRANSITION ZONE.
SUNDAY INTO SUNDAY NIGHT THE ECMWF LIFTS A LOW THROUGH THE AREA WITH
A WEAKER PATTERN NOTED IN THE GFS. AGAIN...FORECAST CONFIDENCE IS
LOW GIVEN THE LACK OF CONSISTENCY AMONGST THE OPERATIONAL MODELS.
A STRONGER DEEPER LOW IS FORECAST TO LIFT OUT OF THE LONGWAVE TROUGH
AND PUSH OUR DIRECTION MONDAY NIGHT INTO TUESDAY. THE ECMWF IS
FURTHER NORTH WITH THE TRACK AND WOULD PUT DOWN SOME SNOW ACROSS OUR
FORECAST AREA. AT FURTHER RANGES LIKE NEXT TUESDAY THOUGH CONFIDENCE
IS LOW.
OVERALL PERIODS OF RAIN/SNOW THROUGH THE LONG TERM WITH TEMPERATURES
NEAR TO SLIGHTLY ABOVE NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1144 PM EST TUE DEC 4 2012
LITTLE CHANGE IN THINKING FROM THE PREVIOUS FORECAST. THE AREA OF
LOW CLOUDS IS TRYING TO MOVE SOUTH BUT SEEMS TO BE STRUGGLING TO
GET SOUTH OF ROUTE 10...WHICH IS WHAT THE NAM12 IS SUGGESTING
WOULD HAPPEN (THROUGH 06Z). THE RAP MODEL BRING THE LOW CLOUDS
FARTHER SOUTH BUT STILL ONLY BRINGS THEM TO I-96 FOR THE MOST
PART. SO I DID NOT CHANGE MY OVERALL TAF SITE FORECAST... BRINGING
MVFR CIGS MKG...GRR AND LAN AND KEEPING AZO...BTL AND JXN CLEAR
THROUGH WEDNESDAY.
&&
.MARINE...
ISSUED AT 335 PM EST TUE DEC 4 2012
SMALL CRAFT ADVISORIES ARE IN EFFECT THROUGH WEDNESDAY FOR NORTHWEST
FLOW COLD ADVECTION BEHIND THE EXITING COLD FRONT. THE SFC HIGH WILL
BRING DECREASING WINDS/WAVES LATE WEDNESDAY INTO WEDNESDAY NIGHT.
&&
.HYDROLOGY...
ISSUED AT 335 PM EST TUE DEC 4 2012
TWO NARROW SWATHS OF HEAVIER RAIN WITH AMOUNTS NEAR ONE INCH FELL
LAST NIGHT. ONE WAS FROM PENTWATER TO TUSTIN AND ANOTHER ONE WAS
FROM THREE RIVERS TO MARSHALL. ELSEWHERE RAIN AMOUNTS WERE MOSTLY
UNDER 0.25 INCH. NO HYDRO PROBLEMS NOTED.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST WEDNESDAY FOR LMZ844>849.
&&
$$
SYNOPSIS...MEADE
SHORT TERM...MEADE
LONG TERM...DUKE
AVIATION...WDM
HYDROLOGY...MEADE
MARINE...MEADE
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
443 AM EST WED DEC 5 2012
.SYNOPSIS...
A COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE AREA TODAY AND REACH
THE SOUTH CAROLINA COAST THIS EVENING. HIGH PRESSURE WILL RETURN
THURSDAY AND FRIDAY. EXPECT THIS HIGH TO BECOME CENTERED OFF THE
EAST COAST WHICH WILL RESULT IN A STRONG SOUTHERLY FLOW OF WARM AND
MOIST AIR OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 435 AM EST WEDNESDAY...ADJUSTED MIN TEMPS UP A COUPLE DEGREES
BASED ON INCREASING CLOUD COVER. PATCHY LIGHT RAIN AND A FEW HEAVIER
SHOWERS ARE DEVELOPING OVER WRN NC AND ALONG THE TN LINE. THIS LINES
UP FAIRLY WELL WITH THE GRADUALLY INCREASING POP TREND IN THE GRIDS.
PREVIOUS DISCUSSION...
A STRONG TROUGH WILL MOVE ACROSS THE NEW ENGLAND STATES
TODAY...WHILE A CUT-OFF SRN STREAM LOW DRIFTS DOWN INTO THE NRN GULF
OF MEXICO. A SFC FRONT WILL STALL OVER THE MOUNTAINS THIS
MORNING...THOUGH HEIGHT RISES ACROSS THE MID-ATLANTIC STATES WILL
SEND THE THE FRONT SURGING SOUTHWARD A LITTLE LATER IN THE DAY. WEAK
H8 FRONTOGENESIS WILL ACCOMPANY THE BNDRY...THOUGH THE DEEP LAYER
FORCING LOOKS WEAK. LOW LEVEL CONVERGENCE WILL POOL MOISTURE AHEAD
OF THE FRONT AND MOST OF THE NUMERICAL MODELS DEVELOP ENOUGH
INSTABILITY OVER THE UPSTATE...SRN NC MTNS AND NE GA TO SUPPORT
SHOWERS AND EVEN A FEW TSTMS THIS AFTERNOON. THE NAM IS A LITTLE
FASTER THAN THE GFS...WHILE THE RUC IS A HAIR SLOWER THAN EITHER
MODEL. I HAVE EXTENDED THUNDER CHANCES UP ACROSS THE SRN NC MTNS AS
I DON/T SEE THE BNDRY MAKING IT THROUGH THESE AREAS UNTIL LATE AFTN.
IN FACT...THE FRONT WILL MAKE IT THROUGH CHARLOTTE AND THE NE
UPSTATE BEFORE THE CLEARS THE ESCARPMENT. CONVECTION IS EXPECTED TO
THEN SETTLE SOUTHWARD ACROSS THE UPSTATE AND NE GA. ATTM I DON/T
EXPECT ANYTHING SEVERE OWING TO THE MOIST MID-LEVELS AND WEAK LAPSE
RATES.
HIGH PRESSURE WILL CONTINUE TO RIDGE DOWN THE EAST SLOPES OF THE
APPALACHIANS TONIGHT. THE 1031 MB SFC HIGH CENTERS OVER PENNSYLVANIA
QUALIFIES AS A CLASSICAL COLD AIR DAMMING...AND IT WILL BRING A GOOD
INFLUX AND COOL AND DRY LOW LEVEL AIR INTO THE REGION. SKIES SHOULD
CLEAR OVERNIGHT ACROSS MUCH OF NORTH CAROLINA...AT LEAST NORTH OF A
LINE FROM CHARLOTTE TO ASHEVILLE...WHILE SKIES REMAIN CLOUDY OVER
THE UPSTATE AND NE GA ATOP THE DAMMING AIRMASS. THE MOISTURE LOOKS
SHALLOW AND PCPN CHANCES WILL BE LOW AND CONFINED TO THE SRN MOST
ZONES.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 245 AM WEDNESDAY...SHORT RANGE MODELS BEGIN THE SHORT RANGE
PERIOD...12Z THURS...IN GOOD AGREEMENT WITH THE POSITION OF THE BACK
DOOR COLD FRONT ACROSS THE UPPER SAVANNAH RIVER VALLEY AND SFC HIGH
PRESSURE CENTERED OVER THE MID ATLANTIC AND NEW ENGLAND STATES. AT
H5...A TROF IS EXPECTED TO PIVOT OVER THE NRN GULF...SUPPORTING THE
FORMATION OF A WEAK LOW NEAR THE MISSISSIPPI DELTA DURING THE
DAYLIGHT HOURS. AT 295K...WEAK ISENTROPIC LIFT IS EXPECTED TO
CONTINUE OVER NE GA AND THE WESTERN CAROLINAS THROUGH THURSDAY.
FORECAST SOUNDINGS INDICATE THAT THE CLOUD LAYER MAY RANGE BETWEEN
5-10 KFT...WITH LLVL NE FLOW. LLVL LIFT AND THICK MOISTURE MAY YIELD
PATCHES OF -RA TO SPRINKLES...BUT MEASURABLE QPF SEEMS UNLIKELY.
HOWEVER...GIVEN THE THICK CLOUD COVER FROM SUNRISE TO SUNSET AND
PERSISTENT NE FLOW...HIGH TEMPERATURES SHOULD VERIFY FAIRLY UNIFORM
ACROSS THE CWA ON THURSDAY. I WILL POPULATE TEMPS FROM THE NAM 2M
TEMPS...YIELDING HIGH TEMPERATURE FORECAST FROM THE MID 50S ALONG
AND EAST OF I-85 TO NEAR 50 ALONG AND NORTH OF I-40.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE CENTER OF HIGH PRESSURE SHOULD
SLIDE OVER THE WESTERN ATLANTIC AS LOW PRESSURE DEVELOPS OVER THE
CENTRAL PLAIN AND MID MISSISSIPPI RIVER VALLEY. FORECAST SOUNDINGS
INDICATE THAT CLOUD COVER WILL REMAIN PLENTIFUL ACROSS THE CWA
THROUGH THE PERIOD. LLVL LIFT AND SYNOPTIC SCALE FORCING WILL REMAIN
VERY WEAK...SUPPORTING MAINLY SCHC POPS ACROSS THE MTNS AND
FOOTHILLS. TEMPERATURES WILL GRADUALLY MODERATE THROUGH THE
PERIOD...REMAINING WELL ABOVE NORMAL AT NIGHT AND NEAR NORMAL FOR
FRIDAY HIGHS.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 240 AM WEDNESDAY...THE MEDIUM RANGE WILL BE A PERIOD OF TIME
UNDER THE INFLUENCE OF A SOUTHERLY FLOW PRIOR TO THE ARRIVAL OF A
COLD FRONT IN THE FIRST HALF OF THE WEEK. HIGH PRESSURE WILL BE
CENTERED NEAR BERMUDA WITH A SOUTHERLY FLOW WHICH WILL CONTINUE
THROUGH THE WEEKEND AND TO START THE WEEK AHEAD OF THE FRONT. ALL
MODELS AGREE ON THE GENERAL WEEKEND SCENARIO WITH THE WARMTH AND
MOISTURE ADVECTION AND SLIGHT TO LOW CHANCE POPS FROM NE GA TO
ACROSS THE WESTERN CAROLINAS.
THE GFS MODEL IS MOST PROGRESSIVE WITH THE FRONT MOVING EAST OF OUR
AREA MONDAY EVENING. SOME CAPE VALUES OF AROUND 20 ON GFS SATURDAY
AFTERNOON IN THE NC MTNS THEN RISE TO AROUND 160 OVER THE SMOKIES
SUNDAY AFTERNOON. IT ALL COMES TOGETHER ON THE GFS MONDAY AFTERNOON
WITH CAPES OF AROUND 160 FROM NE GA TO THE NC MTNS AND 850MB WIND 40
TO 50 KTS AND 700MB WIND 55 TO 65 KTS.
THE LATEST ECMWF WHICH JUST ARRIVED IS CLOSER TO THE GFS NOW IN
TIMING AND HAS THE FRONT EAST OF OUR AREA EARLY TUESDAY MORNING.
EARLIER RUN HAD THE FRONT ARRIVING EARLY TUESDAY AFTERNOON. WIND
SPEEDS ARE COMPARABLE TO THE GFS AND NOW SINCE THE ECMWF FRONT
ARRIVES EARLIER THE CAPES ARE HIGHER AS WELL. ECMWF HAS CAPES OF
400 TO 600 MONDAY AFTERNOON ALONG THE I-85 CORRIDOR. SINCE BOTH ARE
IN BETTER AGREEMENT...WILL INCREASE POPS LATE MONDAY AND THEN
DECREASE POPS TUESDAY AS THE FRONT SHOULD BE OUT OF THE AREA TO
EAST.
TEMPERATURES WILL BE 10 OR MORE DEGREES ABOVE NORMAL AHEAD OF THE
FRONT AND THEN STARTING A COOLING TREND BEHIND THE FRONT ON DAY 7
TUESDAY.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...INCREASING SOUTHWESTERLY FLOW JUST ABOVE THE SURFACE
WILL KEEP CONDITIONS MIXED THROUGH SUNRISE. A DECK OF ALTO-CU WILL
MOVE IN WITHIN THE NEXT COUPLE HOURS. MUCH LIKE LAST NIGHT...THE
HIGHER CLOUDS SHOULD KEEP ANY FOG OR LOW STRATUS FROM DEVELOPING.
SHOWERS ALONG THE COLD FRONT WEST OF THE MOUNTAINS HAVE LARGELY
DISSIPATED THIS MORNING. THE FRONT WILL HANG UP OVER THE MTNS WITH
THE BIG PUSH COMING OUT OF THE NORTH LATER IN THE DAY AND WINDS
SHOULD SHIFT TO THE NE AROUND 18 UTC. SHOWERS AND TSTMS WILL
EVENTUALLY DEVELOP ALONG THE FRONT...BUT THE STRONGER CONVECTION
SHOULD STAY SOUTH OF THE AIRFIELD. A PERIOD OF MVFR CIGS IS EXPECTED
TO ACCOMPANY THE FRONT.
ELSEWHERE...CLOUDS BETWEEN 6-10KFT WILL CONTINUE TO OVERSPREAD THE
REGION TONIGHT. THIS SHOULD PREVENT FOG OR RESTRICTIVE CIGS FROM
DEVELOPING AT ANY OF THE AIRFIELDS THROUGH SUNRISE. RAINFALL ALONG
THE COLD FRONT OVER ERN TN HAS LARGELY DISSIPATED. THE NEXT CHANCE
FOR SIGNIFICATION PCPN ALONG THE BNDRY WILL COME THIS AFTN AS
SHOWERS AND FEW TSTMS DEVELOP ALONG IT AS IT DROPS SOUTH ACROSS THE
REGION. I HAVEN/T ADDED THUNDER TO ANY TAFS YET...BUT IT MAY BE
NEEDED AT THE UPSTATE SITES WITH SUBSEQUENT FORECASTS. THE WINDS
WILL BE SOUTHWEST THIS MORNING...SHIFTING TO NE BEHIND THE FRONT.
NOT EXPECTING AND RESTRICTIVE CIGS OR VSBYS EXPECT PERHAPS IN A
HEAVIER SHOWER.
OUTLOOK...COLD AIR DAMMING MAY RESTRICT CIGS WEDNESDAY NIGHT INTO
FRIDAY. MORNING RESTRICTIONS IN FOG AND STRATUS ARE POSSIBLE EARLY
SATURDAY AND SUNDAY WITH FAIR CONDITIONS EXPECTED DURING THE
AFTERNOONS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY
SHORT TERM...NED
LONG TERM...DEO
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
302 AM EST WED DEC 5 2012
.SYNOPSIS...
A COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE AREA TODAY AND REACH
THE SOUTH CAROLINA COAST THIS EVENING. HIGH PRESSURE WILL RETURN
THURSDAY AND FRIDAY. EXPECT THIS HIGH TO BECOME CENTERED OFF THE
EAST COAST WHICH WILL RESULT IN A STRONG SOUTHERLY FLOW OF WARM AND
MOIST AIR OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
A STRONG TROUGH WILL MOVE ACROSS THE NEW ENGLAND STATES
TODAY...WHILE A CUT-OFF SRN STREAM LOW DRIFTS DOWN INTO THE NRN GULF
OF MEXICO. A SFC FRONT WILL STALL OVER THE MOUNTAINS THIS
MORNING...THOUGH HEIGHT RISES ACROSS THE MID-ATLANTIC STATES WILL
SEND THE THE FRONT SURGING SOUTHWARD A LITTLE LATER IN THE DAY. WEAK
H8 FRONTOGENESIS WILL ACCOMPANY THE BNDRY...THOUGH THE DEEP LAYER
FORCING LOOKS WEAK. LOW LEVEL CONVERGENCE WILL POOL MOISTURE AHEAD
OF THE FRONT AND MOST OF THE NUMERICAL MODELS DEVELOP ENOUGH
INSTABILITY OVER THE UPSTATE...SRN NC MTNS AND NE GA TO SUPPORT
SHOWERS AND EVEN A FEW TSTMS THIS AFTERNOON. THE NAM IS A LITTLE
FASTER THAN THE GFS...WHILE THE RUC IS A HAIR SLOWER THAN EITHER
MODEL. I HAVE EXTENDED THUNDER CHANCES UP ACROSS THE SRN NC MTNS AS
I DON/T SEE THE BNDRY MAKING IT THROUGH THESE AREAS UNTIL LATE AFTN.
IN FACT...THE FRONT WILL MAKE IT THROUGH CHARLOTTE AND THE NE
UPSTATE BEFORE THE CLEARS THE ESCARPMENT. CONVECTION IS EXPECTED TO
THEN SETTLE SOUTHWARD ACROSS THE UPSTATE AND NE GA. ATTM I DON/T
EXPECT ANYTHING SEVERE OWING TO THE MOIST MID-LEVELS AND WEAK LAPSE
RATES.
HIGH PRESSURE WILL CONTINUE TO RIDGE DOWN THE EAST SLOPES OF THE
APPALACHIANS TONIGHT. THE 1031 MB SFC HIGH CENTERS OVER PENNSYLVANIA
QUALIFIES AS A CLASSICAL COLD AIR DAMMING...AND IT WILL BRING A GOOD
INFLUX AND COOL AND DRY LOW LEVEL AIR INTO THE REGION. SKIES SHOULD
CLEAR OVERNIGHT ACROSS MUCH OF NORTH CAROLINA...AT LEAST NORTH OF A
LINE FROM CHARLOTTE TO ASHEVILLE...WHILE SKIES REMAIN CLOUDY OVER
THE UPSTATE AND NE GA ATOP THE DAMMING AIRMASS. THE MOISTURE LOOKS
SHALLOW AND PCPN CHANCES WILL BE LOW AND CONFINED TO THE SRN MOST
ZONES.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 245 AM WEDNESDAY...SHORT RANGE MODELS BEGIN THE SHORT RANGE
PERIOD...12Z THURS...IN GOOD AGREEMENT WITH THE POSITION OF THE BACK
DOOR COLD FRONT ACROSS THE UPPER SAVANNAH RIVER VALLEY AND SFC HIGH
PRESSURE CENTERED OVER THE MID ATLANTIC AND NEW ENGLAND STATES. AT
H5...A TROF IS EXPECTED TO PIVOT OVER THE NRN GULF...SUPPORTING THE
FORMATION OF A WEAK LOW NEAR THE MISSISSIPPI DELTA DURING THE
DAYLIGHT HOURS. AT 295K...WEAK ISENTROPIC LIFT IS EXPECTED TO
CONTINUE OVER NE GA AND THE WESTERN CAROLINAS THROUGH THURSDAY.
FORECAST SOUNDINGS INDICATE THAT THE CLOUD LAYER MAY RANGE BETWEEN
5-10 KFT...WITH LLVL NE FLOW. LLVL LIFT AND THICK MOISTURE MAY YIELD
PATCHES OF -RA TO SPRINKLES...BUT MEASURABLE QPF SEEMS UNLIKELY.
HOWEVER...GIVEN THE THICK CLOUD COVER FROM SUNRISE TO SUNSET AND
PERSISTENT NE FLOW...HIGH TEMPERATURES SHOULD VERIFY FAIRLY UNIFORM
ACROSS THE CWA ON THURSDAY. I WILL POPULATE TEMPS FROM THE NAM 2M
TEMPS...YIELDING HIGH TEMPERATURE FORECAST FROM THE MID 50S ALONG
AND EAST OF I-85 TO NEAR 50 ALONG AND NORTH OF I-40.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE CENTER OF HIGH PRESSURE SHOULD
SLIDE OVER THE WESTERN ATLANTIC AS LOW PRESSURE DEVELOPS OVER THE
CENTRAL PLAIN AND MID MISSISSIPPI RIVER VALLEY. FORECAST SOUNDINGS
INDICATE THAT CLOUD COVER WILL REMAIN PLENTIFUL ACROSS THE CWA
THROUGH THE PERIOD. LLVL LIFT AND SYNOPTIC SCALE FORCING WILL REMAIN
VERY WEAK...SUPPORTING MAINLY SCHC POPS ACROSS THE MTNS AND
FOOTHILLS. TEMPERATURES WILL GRADUALLY MODERATE THROUGH THE
PERIOD...REMAINING WELL ABOVE NORMAL AT NIGHT AND NEAR NORMAL FOR
FRIDAY HIGHS.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 240 AM WEDNESDAY...THE MEDIUM RANGE WILL BE A PERIOD OF TIME
UNDER THE INFLUENCE OF A SOUTHERLY FLOW PRIOR TO THE ARRIVAL OF A
COLD FRONT IN THE FIRST HALF OF THE WEEK. HIGH PRESSURE WILL BE
CENTERED NEAR BERMUDA WITH A SOUTHERLY FLOW WHICH WILL CONTINUE
THROUGH THE WEEKEND AND TO START THE WEEK AHEAD OF THE FRONT. ALL
MODELS AGREE ON THE GENERAL WEEKEND SCENARIO WITH THE WARMTH AND
MOISTURE ADVECTION AND SLIGHT TO LOW CHANCE POPS FROM NE GA TO
ACROSS THE WESTERN CAROLINAS.
THE GFS MODEL IS MOST PROGRESSIVE WITH THE FRONT MOVING EAST OF OUR
AREA MONDAY EVENING. SOME CAPE VALUES OF AROUND 20 ON GFS SATURDAY
AFTERNOON IN THE NC MTNS THEN RISE TO AROUND 160 OVER THE SMOKIES
SUNDAY AFTERNOON. IT ALL COMES TOGETHER ON THE GFS MONDAY AFTERNOON
WITH CAPES OF AROUND 160 FROM NE GA TO THE NC MTNS AND 850MB WIND 40
TO 50 KTS AND 700MB WIND 55 TO 65 KTS.
THE LATEST ECMWF WHICH JUST ARRIVED IS CLOSER TO THE GFS NOW IN
TIMING AND HAS THE FRONT EAST OF OUR AREA EARLY TUESDAY MORNING.
EARLIER RUN HAD THE FRONT ARRIVING EARLY TUESDAY AFTERNOON. WIND
SPEEDS ARE COMPARABLE TO THE GFS AND NOW SINCE THE ECMWF FRONT
ARRIVES EARLIER THE CAPES ARE HIGHER AS WELL. ECMWF HAS CAPES OF
400 TO 600 MONDAY AFTERNOON ALONG THE I-85 CORRIDOR. SINCE BOTH ARE
IN BETTER AGREEMENT...WILL INCREASE POPS LATE MONDAY AND THEN
DECREASE POPS TUESDAY AS THE FRONT SHOULD BE OUT OF THE AREA TO
EAST.
TEMPERATURES WILL BE 10 OR MORE DEGREES ABOVE NORMAL AHEAD OF THE
FRONT AND THEN STARTING A COOLING TREND BEHIND THE FRONT ON DAY 7
TUESDAY.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...INCREASING SOUTHWESTERLY FLOW JUST ABOVE THE SURFACE
WILL KEEP CONDITIONS MIXED THROUGH SUNRISE. A DECK OF ALTO-CU WILL
MOVE IN WITHIN THE NEXT COUPLE HOURS. MUCH LIKE LAST NIGHT...THE
HIGHER CLOUDS SHOULD KEEP ANY FOG OR LOW STRATUS FROM DEVELOPING.
SHOWERS ALONG THE COLD FRONT WEST OF THE MOUNTAINS HAVE LARGELY
DISSIPATED THIS MORNING. THE FRONT WILL HANG UP OVER THE MTNS WITH
THE BIG PUSH COMING OUT OF THE NORTH LATER IN THE DAY AND WINDS
SHOULD SHIFT TO THE NE AROUND 18 UTC. SHOWERS AND TSTMS WILL
EVENTUALLY DEVELOP ALONG THE FRONT...BUT THE STRONGER CONVECTION
SHOULD STAY SOUTH OF THE AIRFIELD. A PERIOD OF MVFR CIGS IS EXPECTED
TO ACCOMPANY THE FRONT.
ELSEWHERE...CLOUDS BETWEEN 6-10KFT WILL CONTINUE TO OVERSPREAD THE
REGION TONIGHT. THIS SHOULD PREVENT FOG OR RESTRICTIVE CIGS FROM
DEVELOPING AT ANY OF THE AIRFIELDS THROUGH SUNRISE. RAINFALL ALONG
THE COLD FRONT OVER ERN TN HAS LARGELY DISSIPATED. THE NEXT CHANCE
FOR SIGNIFICATION PCPN ALONG THE BNDRY WILL COME THIS AFTN AS
SHOWERS AND FEW TSTMS DEVELOP ALONG IT AS IT DROPS SOUTH ACROSS THE
REGION. I HAVEN/T ADDED THUNDER TO ANY TAFS YET...BUT IT MAY BE
NEEDED AT THE UPSTATE SITES WITH SUBSEQUENT FORECASTS. THE WINDS
WILL BE SOUTHWEST THIS MORNING...SHIFTING TO NE BEHIND THE FRONT.
NOT EXPECTING AND RESTRICTIVE CIGS OR VSBYS EXPECT PERHAPS IN A
HEAVIER SHOWER.
OUTLOOK...COLD AIR DAMMING MAY RESTRICT CIGS WEDNESDAY NIGHT INTO
FRIDAY. MORNING RESTRICTIONS IN FOG AND STRATUS ARE POSSIBLE EARLY
SATURDAY AND SUNDAY WITH FAIR CONDITIONS EXPECTED DURING THE
AFTERNOONS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY
SHORT TERM...NED
LONG TERM...DEO
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
329 AM CST WED DEC 5 2012
.SHORT TERM...
TODAY.....FORECAST CONFIDENCE HIGH.
A DRY DAY WITH MID-UPPER LEVEL RIDGING BUILDING OVER REGION... AS
SURFACE HIGH PRESSURE SLIDES ACROSS THE WESTERN GREAT LAKES.
WATCHING BAND OF LAKE-EFFECT CUMULUS AROUND 3K FT DROPPING SOUTH
THROUGH LOWER MICHIGAN AND ERN HALF OF LAKE MI ON IR SATELLITE
IMAGERY. COULD BE SOME TWO-LAKE MOISTURE FEEDING THESE CLOUDS THAT
ARE ON LEADING EDGE OF POOL OF COLDEST 850 MB TEMPS THAT SLIDES BY
TO THE NORTHEAST TODAY. NW WINDS VEER NE BELOW 3K FT BY 15Z...BUT
WITH RELATIVELY WARM 850 MB TEMPS STAYING AROUND 0C WITH SUBSIDENCE
INVERSION DELTA T/S REMAIN AROUND 7C TO 9C. STEEP LAPSE RATES BELOW
2K FT/930 MB/ BUT LIMITED MOISTURE. EXCEPTION ARE RAP SOUNDINGS
WHICH INDICATE A BROKEN DECK FORMING MID AFTERNOON INTO THE EVENING.
WILL KEEP SKY COVER NO MORE THAN 50 PERCENT FOR NOW AND KEEP AN EYE
ON TRENDS.
WARM AIR ADVECTION BEGINS THIS AFTERNOON...WITH A 925 MB TEMPERATURE
GRADIENT SOUTHWEST TO NORTHEAST YIELDING NO BETTER THAN MID 30 HIGHS
IN THE NORTHEAST WITH AROUND 40 IN THE SOUTHWEST.
TONIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH.
WAA BRINGS MID TO HIGH LEVEL CLOUDS ACROSS THE FORECAST AREA THIS
EVENING...WITH 1-2 UBAR/SEC ISENTROPIC ADIABATIC OMEGA BRUSHING THE
NORTHWEST HALF OF CWA BETWEEN 06Z AND 12Z THURSDAY. HOWEVER MODEL
SOUNDINGS SHOW A VERY DRY LAYER BELOW 6-7K FT THAT NEVER
SATURATES...SUPPORTED BY CONDENSATION PRESSURE DEFICITS THAT NEVER
LOWER BELOW 100 MB ON 280K AND 285K SURFACES. WILL LIMIT SLIGHT
CHANCE POPS TO FAR NW. INCREASING CLOUDS AND WARM AIR ADVECTION ON
STRENGTHENING SOUTH WINDS LEADS TO A NON-DIURNAL TREND TO
TEMPERATURES...WITH LOWS AROUND 03Z THEN A SLOW RISE THROUGH
DAYBREAK.
THURSDAY THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM
STRONG LOW PRESSURE WILL ONCE AGAIN TRAVERSE EWD ACROSS CANADA
DURING THIS PERIOD BRINGING SSWLY FLOW AND LOW TO MID LEVEL WARM
ADVECTION FOR THU. THE WARM ADVECTION WILL LEAD TO WIDESPREAD
CLOUDS AND SMALL CHANCES OF RAIN FOR THU. THE CLOUDS WILL KEEP THE
TEMPS IN THE 40S THIS TIME AROUND. THE TRAILING COLD FRONT WILL
THEN SLOWLY MOVE SWD THROUGH THE AREA THU NT. MORE IMPORTANTLY...850-700
MB FRONTOGENESIS WILL BECOME ORGANIZED VIA CONFLUENT FLOW IN THAT
LAYER AS THE POLAR JET STREAM DROPS MORE SWD INTO THE USA. MOST
MODELS PRODUCE A SW TO NE BAND OF LGT RAIN THU NT SO WENT WITH
LIKELY POPS FOR THE CENTRAL AND SOUTHERN PORTIONS OF THE CWA.
.LONG TERM...
FRIDAY NIGHT THROUGH TUESDAY...FORECAST CONFIDENCE LOW TO MEDIUM
A SHORTWAVE TROUGH WILL PASS FROM THE NRN PLAINS THROUGH WI FOR
FRI NT INTO SATURDAY BRINGING SMALL CHANCES OF LGT SNOW WITH THE
EXCEPTION OF A MIXTURE SAT AFTERNOON. AT THE SURFACE...WEAK HIGH
PRESSURE WILL BUILD INTO THE REGION.
DURING THE WEEKEND AN UPPER TROUGH WILL DIG INTO THE PLAINS AND
THEN SWING NEWD TOWARD THE OHIO RIVER VALLEY AND ERN GREAT LAKES.
AT THE SFC A MORE ORGANIZED SFC LOW WILL DEVELOP TO ERN IL BY 00Z MON
AND THEN NEWD THROUGH MI AND INTO QUEBEC FOR LATE ON MON. TIMING
AND STRENGTH DIFFERENCES REMAIN AMONG THE MODELS BUT NONETHELESS
SHOWING BETTER AGREEMENT. THIS SCENARIO RESULTS IN BETTER CHANCES
OF JUST SNOW AWAY FROM FAR SE WI BUT WILL STILL MENTION RAIN AND
SNOW OVER MOST OF THE AREA DUE TO UNCERTAINTY. PCPN TYPE WILL BE MAINLY
LIGHT SNOW FOR SUN NT THROUGH TUE WHILE ON THE BASKSIDE OF THE LOW
AND ANOTHER WEAK SHORTWAVE TROUGH FOR TUE.
&&
.AVIATION/12Z TAFS/...
WILL KEEP VFR CONDITIONS THROUGH THE FORECAST. CONCERN WITH
POTENTIAL MVFR LAKE-CLOUDS AS NORTH-NORTHWEST WINDS TURN NORTHEAST
LATE THIS MORNING...THEN EAST MID-AFTERNOON. SUBSIDENCE INVERSION
HOLDS STEEPER LAPSE RATES TO 2K FT OR LESS WITH LITTLE DEPTH TO
SATURATED LAYER ON NAM AND GFS SOUNDINGS...THOUGH RAP SOUNDINGS
INDICATE POTENTIAL FOR A BROKEN DECK AROUND 2K FT THIS AFTERNOON.
WITH COLD POOL THAT IS GENERATING CLOUDS OVER LOWER MICHIGAN SLIDING
BY TO THE NORTHEAST...WILL KEEP CURRENT SCATTERED 2K FT FOR TODAY
AND MONITOR DEVELOPMENTS TOWARD ISSUANCE.
COULD BE A PERIOD OF LOW-LEVEL WIND SHEAR THIS EVENING WITH 925 MB
WINDS INCREASING TO 30-35 KNOTS...BEFORE WARM AIR ADVECTION ALLOWS
ENOUGH MIXING TO RAISE SURFACE WINDS. DIFFERENTIAL IS HOVERING NEAR
BUT JUST BELOW CRITERIA SO WILL LEAVE OUT FOR NOW BUT BRIEF NEXT
SHIFT TO WATCH LATER MODEL RUNS.
&&
.MARINE...
QUIET TODAY...WITH NORTHWEST WINDS VEERING NORTHEAST AND THEN EAST
DURING THE DAY. ISSUED A SMALL CRAFT ADVISORY FOR THE NORTHERN TWO
NEARSHORE ZONES FOR 08Z THURSDAY TO 00Z FRIDAY AS SOUTH WINDS
INCREASE AHEAD OF LOW PRESSURE DEEPENING AS IT TRACKS FROM NEAR LAKE
WINNIPEG TO HUDSON BAY. THE WINDS WILL BUILD HIGH WAVES FROM
MILWAUKEE NORTH. THOUGH THERE WILL BE A FEW GUSTS TO 25 KNOTS...
WAVES SHOULD REMAIN JUST BELOW CRITERIA SOUTH OF MILWAUKEE DUE TO
MORE LIMITED FETCH. WINDS TURN SW AROUND 18Z THURSDAY AND DIMINISH
BELOW CRITERIA THROUGH THE AFTERNOON...BUT 00Z FRIDAY END TIME WILL
ALLOW WAVES TO SUBSIDE.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 2 AM TO 6 PM CST THURSDAY FOR LMZ643-
644.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...REM
THURSDAY THROUGH TUESDAY...GEHRING
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
1025 AM EST WED DEC 5 2012
.DISCUSSION...
CURRENT...WEAK LOW LEVEL TROUGH WHICH WAS NOTED OVER THE ATLC IN THE
TUE AFTERNOON AFD PUSHED ONSHORE EARLY THIS MORNING...AND PRODUCED
DECENT AMOUNT OF SHOWER ACTIVITY ALONG COASTAL AREAS. THIS WEAK LOW
LEVEL FEATURE IS EVIDENT IN SFC METARS AND RUC LOW LEVEL (H925-H850)
WIND/VORT ANALYSES AND HAS PIVOTED NWWD AND IS LIFTING ACROSS THE
NRN CWA. WEAK LOW LEVEL CONVG/ASCENT ASCD WITH THIS FEATURE IS
PRODUCING QUITE BIT OF LOW TO MID LEVEL BKN-OVC CLOUDINESS FROM
OSCEOLA/BREVARD COUNTIES NORTHWARD AS THE MID LEVEL DECK "PANCAKES"
UNDERNEATH THE STILL STOUT CAP BETWEEN H80-H70. LATEST RADAR IMAGERY
SHOWS THAT PRECIP HAS PRETTY MUCH DISSIPATED OVER LAND AS IT MOVES
SLOWLY NW.
REST OF TODAY...LOCAL MESOMODEL GUIDANCE SHOWS THE WEAK TROUGH WILL
BE SLOW TO DAMPEN OUT THIS AFTERNOON...WHICH WOULD RESULT IN BROKEN
MID LEVEL CLOUD COVER PERSISTING ACROSS THE NORTHERN HALF CWA LONGER
THAN ADVERTISED...WHICH MAY ALSO RESULT IN MAX TEMPS A DEG OR SO
LOWER. SINCE BREAKUP OF THE LOW-MID CLOUDS IS EXPECTED TO TAKE A BIT
LONGER WILL GO AHEAD AND TWEAK SKY COVER AND TEMP GRIDS TOWARD THIS
END. WITH RESPECT TO POPS...WILL LIKELY TWEAK THEM DOWN TO 20 PCT
AWAY FROM THE CURRENT POSITION OF THE TROUGH.
&&
.AVIATION...STUBBORN IFR STRATUS DECK BKN-OVC004-007 STILL NOTED IN
METARS ALONG COASTAL VOLUSIA/NORTH BREVARD (OMN-DAB-EVB-TTS-TIX).
ALTHOUGH IT`S BEEN SLOW TO BREAK UP THUS FAR BECAUSE OF THE OVC-BKN
DECK ABOVE IT (6-7KFT) IT SHOULD DO SO SHORTLY VIA DIURNAL HEATING/
MIXING. WILL PROBABLY NEED TO HANG ON TO VFR CIGS BKN060-070 ALONG
/NORTH OF MLB-ISM INTO THIS AFTERNOON.
&&
.MARINE...WINDS CONTINUE TO DECREASE TODAY. ESE AROUND 10KT OR LESS
TODAY THROUGH TONIGHT. SEAS 3-5 FT IN LINGERING SWELL.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...CRISTALDI
LONG TERM/IMPACT WX....WEITLICH
AREA FORECAST DISCUSSION
NWS BILLINGS MT
331 AM MST WED DEC 5 2012
.SHORT TERM...VALID FOR TDY AND THU...
THE ENERGETIC SHORT WAVE TROUGH OBSERVED OVER BRITISH COLUMBIA AT
10 UTC WILL HELP DRIVE A PATTERN CHANGE THE NEXT FEW DAYS...WHICH
WILL BEGIN WITH A COLD FRONTAL PASSAGE THIS AFTERNOON.
TODAY...A LOW- AND MID-LEVEL THERMAL RIDGE WILL CROSS THE AREA IN
ADVANCE OF A SURFACE COLD FRONT...WITH 850-HPA TEMPERATURES OF 10
TO 12 C IN PLACE ACROSS THE AREA AROUND 18 UTC. ALL OF THE 00 UTC
GUIDANCE IS A BIT FASTER WITH THE FRONTAL PASSAGE...SUGGESTING IT
COULD BE ALL THE WAY THROUGH SOUTHEASTERN MT BY 00 UTC. HIGHS ARE
THUS A BIT DIFFICULT TO PIN DOWN TODAY...AND WITH THE UNCERTAINTY
IN FRONTAL TIMING AND POTENTIAL FOR ABUNDANT CLOUDS WE FELT USING
THE 00 UTC MULTI-MODEL CONSENSUS WAS THE BEST APPROACH FOR HIGHS.
MOISTURE CHANNEL IMAGERY AT 10 UTC SHOWS SUBTLE DRYING ALOFT OVER
NORTHERN CA...WHICH IS LIKELY ASSOCIATED WITH A NARROW 80+ KT JET
STREAK THAT MOST 00 UTC GUIDANCE PICKED UP ON. THE EXIT REGION OF
THAT JET CIRCULATION IS EXPECTED TO CROSS THE AREA DURING THE MID
TO LATE AFTERNOON...FAVORABLY TIMING ITS PASSAGE WITH THE FRONTAL
ZONE. THAT SHOULD CREATE AN ENVIRONMENT FAVORABLE FOR SOME SHOWER
ACTIVITY...MUCH LIKE THE 03 UTC SREF AND RECENT RAP RUNS SUGGEST.
CLIMATOLOGICALLY...DOWNSLOPE FLOW WILL USUALLY FAVOR SHOWERS EAST
OF BILLINGS...AND EVEN THE 03 UTC SREF PICKS UP ON THAT...SO POPS
ARE RELATIVELY HIGHER /IN THE 30 PERCENT RANGE/ FOR MILES CITY...
HYSHAM...AND BROADUS AFTER 18 UTC. NOTE THAT THE JET STREAK COULD
HELP ENHANCE SNOW OVER THE MOUNTAINS FOR A TIME TOO...AND MOST OF
THE 00 UTC GUIDANCE SUPPORTS ONE TO TWO INCHES NEAR COOKE CITY.
AS FOR WINDS...WE DECIDED TO LEAVE THE ADVISORY UP FOR LIVINGSTON
AND NYE WITH THE MORNING FORECAST SINCE OBSERVED SPEEDS AT 10 UTC
ARE NEAR CRITERIA. THERE IS OFTEN A BIT OF A BUMP UP IN GAP WINDS
NEAR AND JUST AFTER SUNRISE AND THAT IS POSSIBLE IN THIS CASE TOO
WITH THE INVERSION ABOVE THE VALLEY FLOORS IN PLACE UNTIL 15 UTC.
AFTER THAT TIME...THE STABLE LAYER ERODES AND THE GRADIENT SHOULD
BECOME UNFAVORABLE FOR GAP-INDUCED WINDS. MIXING WILL KEEP THINGS
GUSTY THOUGH...AND IN FACT THE ENTIRE AREA COULD HAVE A PERIOD OF
GUSTY WINDS BETWEEN ABOUT 21 AND 03 UTC AS A 4 HPA/3 HOUR SURFACE
PRESSURE RISE MAXIMUM FOLLOWS THE COLD FRONT.
TONIGHT...WEAK FRONTOGENESIS IS EXPECTED FROM ABOUT LIVINGSTON TO
SHERIDAN...SO SOME LOW POPS ARE ADVERTISED FOR THOSE AREAS. WINDS
ALOFT SHIFT A BIT WEST-NORTHWESTERLY...WHICH SHOULD HELP MOISTURE
DIMINISH IN THE MOUNTAINS.
THU AND THU NIGHT...OUR MAIN FOCUS IS ON THE POTENTIAL FOR A BAND
OF ACCUMULATING SNOW...MAINLY SOUTH OF A LINE FROM LIVINGSTON AND
BILLINGS TO BROADUS. THE LAST SEVERAL MODEL CYCLES HAVE AGREED ON
A BURST OF MID-LEVEL FRONTOGENESIS CENTERED AROUND 700 HPA ACROSS
THE AREA BETWEEN ABOUT 18 AND 06 UTC...WITH VERTICAL MOTION AIDED
BY THE EXIT REGION OF A 120 KT 300-HPA JET STREAK DIVING INTO WY.
THE 00 UTC GUIDANCE GENERALLY PUSHED THE FRONTOGENESIS JUST A BIT
FURTHER SOUTH...AND THUS HAS THE HIGHER QPF SOUTH OF BILLINGS. WE
KEPT LIKELY POPS IN THE FORECAST EVEN FOR BILLINGS THOUGH BECAUSE
TRENDS LIKE THIS CAN SOMETIMES BE MISLEADING WITH A FRONTOGENESIS
BAND. WET BULB ZERO HEIGHTS SUGGEST ALL OF THE PRECIPITATION WILL
BE IN THE FORM OF SNOW...EVEN WHEN SURFACE TEMPERATURES ARE ABOVE
32 F ON THU AFTERNOON...SO WE DID DECIDE TO FORGO ANY MIX OF RAIN
AND SNOW IN THE FORECAST. TAKEN AT FACE VALUE...THE 00 UTC MODELS
ACTUALLY SHOW WET BULB ZERO HEIGHTS JUST HIGH ENOUGH FOR A MIX IN
THE PARADISE VALLEY DURING THE DAY THU...BUT THE 03 UTC SREF ONLY
SHOWS SNOW WITH THE NCEP PRECIPITATION-TYPE ALGORITHM...WHICH WAS
ENOUGH FOR US TO KEEP THINGS AS ALL SNOW FOR NOW. ALTHOUGH QPF IS
NOT EXPECTED TO BE SIGNIFICANT...GFS FORECAST SOUNDINGS SIMULATED
MOST OF THE OMEGA WITHIN THE DENDRITIC GROWTH ZONE THU NIGHT. THE
SNOW-TO-LIQUID RATIOS DERIVED FROM 03 UTC SREF OUTPUT WERE AROUND
15 TO 1 ON THU NIGHT TOO...SO WE COULD EASILY PICK UP ONE TO FOUR
INCHES OF SNOW IN SOME AREAS. THIS COULD REQUIRE AN ADVISORY DOWN
THE ROAD...ONCE WE ARE CONFIDENT IN THE PLACEMENT OF THE FORCING.
HOWEVER...LOW-LEVEL UPSLOPE FLOW WILL BE LACKING...AND DEEP-LAYER
MOISTURE IS MODEST WITH PRECIPITABLE WATER VALUES OF 0.25 INCHES.
THUS...THIS EVENT IS FAR FROM A SLAM DUNK. SCHULTZ
.LONG TERM...VALID FOR FRI...SAT...SUN...MON...TUE...
MEDIUM RANGE GUIDANCE REMAINS IN FAIRLY GOOD AGREEMENT WITH A
SPEEDY NORTHWEST FLOW DOMINATING THE REGION. NUMEROUS DISTURBANCES
WILL RIDE THE FLOW ALL THE WAY THROUGH THE MIDDLE OF NEXT WEEK
AND BEYOND. WHILE THE PATTERN WILL BE ACTIVE AND CHALLENGING WITH
TIMING AND STRENGTH OF EACH SYSTEM...NO WIDESPREAD AND SIGNIFICANT
WEATHER IMPACTS ARE ANTICIPATED AT THIS TIME. ALTHOUGH...NORTHWEST
FLOW CAN BE TRICKY AND WILL HAVE TO BE MONITORED FOR POTENTIAL
STRENGTHENING OF ANY PARTICULAR WAVE AS WE PROGRESS THROUGH TIME.
ITS ADVISED TO STAY TUNED TO THE FORECAST.
FORCING WITH EACH WAVE SHOULD BE ENOUGH TO PRODUCE PERIODIC
EPISODES OF LIGHT SNOWFALL. WITH THE ADVERTISED STRENGTH AND SPEED
OF THESE DISTURBANCES...NO PARTICULAR SYSTEM RIGHT NOW LOOKS TO
BE ABLE TO PRODUCE MORE THAN A AN INCH OR TWO OF SNOW AT
BEST...MORE IN SOME FAVORED FOOTHILLS AND MOUNTAINS. IT LOOKS LIKE
IT WILL BE A WINDY PERIOD AS WELL WITH EACH PASSING SURFACE LOW
PRESSURE AND COLD FRONTS. THIS COULD BE AN ADDED IMPACT TO WATCH
FOR LOCAL BLOWING SNOW AT TIMES. THE FLOW WILL ALSO KEEP
TEMPERATURES IN CHECK THROUGH THE PERIOD...SLIGHTLY BELOW OUR
NORMALS.
FRIEDERS
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL OVER THE NEXT 24 HOUR PERIOD. A
COLD FRONT THAT WILL MOVE THROUGH THE AREA THIS AFTERNOON MAY
PRODUCE WIDELY SCATTERED RAIN AND SNOW SHOWERS INTO TONIGHT. THEY
ARE NEXT EXPECTED TO IMPACT CEILINGS OR VISIBILITIES EXCEPT FOR
OCCASIONAL MOUNTAIN OBSCURATIONS. GUSTY WINDS WILL CONTINUE TO
PLAGUE AREAS IN AND AROUND LIVINGSTON WITH GUSTS GREATER THAN 40
KTS POSSIBLE THROUGH MID DAY TODAY. FRIEDERS
&&
.PRELIMINARY POINT TEMP/POPS...
TDY THU FRI SAT SUN MON TUE
-------------------------------------------------------
BIL 058 028/036 024/034 026/029 011/024 019/032 021/037
2/W 14/S 63/S 24/S 31/B 13/S 11/B
LVM 053 026/034 019/034 026/026 008/023 015/031 015/033
2/W 26/S 63/S 44/S 32/S 34/S 31/E
HDN 059 029/037 025/035 020/029 009/023 015/030 017/035
3/W 22/S 63/S 24/S 31/B 13/S 11/B
MLS 055 025/037 021/032 019/029 011/021 015/029 019/033
3/W 22/S 43/S 24/S 31/B 13/S 11/B
4BQ 057 027/038 021/034 019/029 011/022 011/028 017/032
3/W 32/S 64/S 14/S 31/B 13/S 11/B
BHK 056 022/035 020/032 017/028 011/020 011/026 017/030
3/W 21/B 32/S 24/S 31/B 13/S 11/E
SHR 056 027/036 019/033 015/028 007/018 009/024 011/033
2/W 22/S 63/S 14/S 31/B 13/S 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY IN EFFECT UNTIL 6 PM MST THIS EVENING FOR ZONES
65-66.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
943 AM EST WED DEC 5 2012
.SYNOPSIS...
A COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE AREA TODAY AND REACH
THE SOUTH CAROLINA COAST THIS EVENING. HIGH PRESSURE WILL RETURN
THURSDAY AND FRIDAY. EXPECT THIS HIGH TO BECOME CENTERED OFF THE
EAST COAST WHICH WILL RESULT IN A STRONG SOUTHERLY FLOW OF WARM AND
MOIST AIR OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 935 AM...RADAR SHOWING SHRA OVER THE NC PIEDMONT AND NE GA AND
NWRN UPSTATE AHEAD OF THE COLD FRONT SLOWLY MOVING ACROSS THE AREA.
EXPECT THE SHRA TO DIMINISH ACROSS THE NC PIEDMONT THIS MORNING
LEAVING ONLY SCT SHRA. THE SHRA OVER GA/SC WILL CONTINUE THRU THE
AFTERNOON AND MOVE EAST AND SOUTH ACROSS THAT AREA AS THE FRONT
SLOWLY SAGS SWD. WITH MOISTURE POOLING ALONG THE FRONT OVER THAT
AREA...DEW POINTS WILL REMAIN RELATIVELY HIGH FOR THIS TIME OF YEAR.
12Z RAOBS SHOW ELEVATED INSTABILITY OVER THE AREA WITH WEAK LAPSE
RATE INCREASE DUE TO COOLING MID LEVELS. HAVE RETAINED TSRA WORDING
ACROSS NE GA/UPSTATE IN LINE WITH THESE TRENDS. TEMPS WILL BE TRICKY
WITH THE FRONTAL MOVEMENT AND VERY WARM START TO THE DAY. UPDATED
HIGHS BASED ON CURRENT GUIDANCE WHICH DID MAKE SOME MINOR CHANGES.
AS OF 635 AM EST WEDNESDAY...LOCAL RADAR...SFC OBS AND IFLOWS
OBSERVATIONS SHOW THAT SHOWERS HAVE INCREASED OVER THE NC AND NE GA
MTNS THE PAST FEW HOURS. THIS IS IN LINE WITH THE FORECAST. SOME
LIGHTER SHOWERS ARE ALSO FALLING OVER THE FOOTHILLS AND
PIEDMONT...BUT THEY ARE LIGHTER. A MORE CONCENTRATED AREA OF RAIN
HAS DEVELOPED OVER NRN GA AND SHOULD MOVE INTO RABUN...HABERSHAM AND
OCONEE COUNTIES OVER THE NEXT COUPLE HOURS.
AS OF 435 AM EST WEDNESDAY...ADJUSTED MIN TEMPS UP A COUPLE DEGREES
BASED ON INCREASING CLOUD COVER. PATCHY LIGHT RAIN AND A FEW HEAVIER
SHOWERS ARE DEVELOPING OVER WRN NC AND ALONG THE TN LINE. THIS LINES
UP FAIRLY WELL WITH THE GRADUALLY INCREASING POP TREND IN THE GRIDS.
PREVIOUS DISCUSSION...
A STRONG TROUGH WILL MOVE ACROSS THE NEW ENGLAND STATES
TODAY...WHILE A CUT-OFF SRN STREAM LOW DRIFTS DOWN INTO THE NRN GULF
OF MEXICO. A SFC FRONT WILL STALL OVER THE MOUNTAINS THIS
MORNING...THOUGH HEIGHT RISES ACROSS THE MID-ATLANTIC STATES WILL
SEND THE THE FRONT SURGING SOUTHWARD A LITTLE LATER IN THE DAY. WEAK
H8 FRONTOGENESIS WILL ACCOMPANY THE BNDRY...THOUGH THE DEEP LAYER
FORCING LOOKS WEAK. LOW LEVEL CONVERGENCE WILL POOL MOISTURE AHEAD
OF THE FRONT AND MOST OF THE NUMERICAL MODELS DEVELOP ENOUGH
INSTABILITY OVER THE UPSTATE...SRN NC MTNS AND NE GA TO SUPPORT
SHOWERS AND EVEN A FEW TSTMS THIS AFTERNOON. THE NAM IS A LITTLE
FASTER THAN THE GFS...WHILE THE RUC IS A HAIR SLOWER THAN EITHER
MODEL. I HAVE EXTENDED THUNDER CHANCES UP ACROSS THE SRN NC MTNS AS
I DON/T SEE THE BNDRY MAKING IT THROUGH THESE AREAS UNTIL LATE AFTN.
IN FACT...THE FRONT WILL MAKE IT THROUGH CHARLOTTE AND THE NE
UPSTATE BEFORE THE CLEARS THE ESCARPMENT. CONVECTION IS EXPECTED TO
THEN SETTLE SOUTHWARD ACROSS THE UPSTATE AND NE GA. ATTM I DON/T
EXPECT ANYTHING SEVERE OWING TO THE MOIST MID-LEVELS AND WEAK LAPSE
RATES.
HIGH PRESSURE WILL CONTINUE TO RIDGE DOWN THE EAST SLOPES OF THE
APPALACHIANS TONIGHT. THE 1031 MB SFC HIGH CENTERS OVER PENNSYLVANIA
QUALIFIES AS A CLASSICAL COLD AIR DAMMING...AND IT WILL BRING A GOOD
INFLUX AND COOL AND DRY LOW LEVEL AIR INTO THE REGION. SKIES SHOULD
CLEAR OVERNIGHT ACROSS MUCH OF NORTH CAROLINA...AT LEAST NORTH OF A
LINE FROM CHARLOTTE TO ASHEVILLE...WHILE SKIES REMAIN CLOUDY OVER
THE UPSTATE AND NE GA ATOP THE DAMMING AIRMASS. THE MOISTURE LOOKS
SHALLOW AND PCPN CHANCES WILL BE LOW AND CONFINED TO THE SRN MOST
ZONES.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 245 AM WEDNESDAY...SHORT RANGE MODELS BEGIN THE SHORT RANGE
PERIOD...12Z THURS...IN GOOD AGREEMENT WITH THE POSITION OF THE BACK
DOOR COLD FRONT ACROSS THE UPPER SAVANNAH RIVER VALLEY AND SFC HIGH
PRESSURE CENTERED OVER THE MID ATLANTIC AND NEW ENGLAND STATES. AT
H5...A TROF IS EXPECTED TO PIVOT OVER THE NRN GULF...SUPPORTING THE
FORMATION OF A WEAK LOW NEAR THE MISSISSIPPI DELTA DURING THE
DAYLIGHT HOURS. AT 295K...WEAK ISENTROPIC LIFT IS EXPECTED TO
CONTINUE OVER NE GA AND THE WESTERN CAROLINAS THROUGH THURSDAY.
FORECAST SOUNDINGS INDICATE THAT THE CLOUD LAYER MAY RANGE BETWEEN
5-10 KFT...WITH LLVL NE FLOW. LLVL LIFT AND THICK MOISTURE MAY YIELD
PATCHES OF -RA TO SPRINKLES...BUT MEASURABLE QPF SEEMS UNLIKELY.
HOWEVER...GIVEN THE THICK CLOUD COVER FROM SUNRISE TO SUNSET AND
PERSISTENT NE FLOW...HIGH TEMPERATURES SHOULD VERIFY FAIRLY UNIFORM
ACROSS THE CWA ON THURSDAY. I WILL POPULATE TEMPS FROM THE NAM 2M
TEMPS...YIELDING HIGH TEMPERATURE FORECAST FROM THE MID 50S ALONG
AND EAST OF I-85 TO NEAR 50 ALONG AND NORTH OF I-40.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE CENTER OF HIGH PRESSURE SHOULD
SLIDE OVER THE WESTERN ATLANTIC AS LOW PRESSURE DEVELOPS OVER THE
CENTRAL PLAIN AND MID MISSISSIPPI RIVER VALLEY. FORECAST SOUNDINGS
INDICATE THAT CLOUD COVER WILL REMAIN PLENTIFUL ACROSS THE CWA
THROUGH THE PERIOD. LLVL LIFT AND SYNOPTIC SCALE FORCING WILL REMAIN
VERY WEAK...SUPPORTING MAINLY SCHC POPS ACROSS THE MTNS AND
FOOTHILLS. TEMPERATURES WILL GRADUALLY MODERATE THROUGH THE
PERIOD...REMAINING WELL ABOVE NORMAL AT NIGHT AND NEAR NORMAL FOR
FRIDAY HIGHS.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 240 AM WEDNESDAY...THE MEDIUM RANGE WILL BE A PERIOD OF TIME
UNDER THE INFLUENCE OF A SOUTHERLY FLOW PRIOR TO THE ARRIVAL OF A
COLD FRONT IN THE FIRST HALF OF THE WEEK. HIGH PRESSURE WILL BE
CENTERED NEAR BERMUDA WITH A SOUTHERLY FLOW WHICH WILL CONTINUE
THROUGH THE WEEKEND AND TO START THE WEEK AHEAD OF THE FRONT. ALL
MODELS AGREE ON THE GENERAL WEEKEND SCENARIO WITH THE WARMTH AND
MOISTURE ADVECTION AND SLIGHT TO LOW CHANCE POPS FROM NE GA TO
ACROSS THE WESTERN CAROLINAS.
THE GFS MODEL IS MOST PROGRESSIVE WITH THE FRONT MOVING EAST OF OUR
AREA MONDAY EVENING. SOME CAPE VALUES OF AROUND 20 ON GFS SATURDAY
AFTERNOON IN THE NC MTNS THEN RISE TO AROUND 160 OVER THE SMOKIES
SUNDAY AFTERNOON. IT ALL COMES TOGETHER ON THE GFS MONDAY AFTERNOON
WITH CAPES OF AROUND 160 FROM NE GA TO THE NC MTNS AND 850MB WIND 40
TO 50 KTS AND 700MB WIND 55 TO 65 KTS.
THE LATEST ECMWF WHICH JUST ARRIVED IS CLOSER TO THE GFS NOW IN
TIMING AND HAS THE FRONT EAST OF OUR AREA EARLY TUESDAY MORNING.
EARLIER RUN HAD THE FRONT ARRIVING EARLY TUESDAY AFTERNOON. WIND
SPEEDS ARE COMPARABLE TO THE GFS AND NOW SINCE THE ECMWF FRONT
ARRIVES EARLIER THE CAPES ARE HIGHER AS WELL. ECMWF HAS CAPES OF
400 TO 600 MONDAY AFTERNOON ALONG THE I-85 CORRIDOR. SINCE BOTH ARE
IN BETTER AGREEMENT...WILL INCREASE POPS LATE MONDAY AND THEN
DECREASE POPS TUESDAY AS THE FRONT SHOULD BE OUT OF THE AREA TO
EAST.
TEMPERATURES WILL BE 10 OR MORE DEGREES ABOVE NORMAL AHEAD OF THE
FRONT AND THEN STARTING A COOLING TREND BEHIND THE FRONT ON DAY 7
TUESDAY.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...MAIN AREA OF SHRA SHUD REMAIN NORTH OF THE AIRFIELD THIS
MORNING. CANNOT RULE OUT AN SHRA AS THE FRONT MOVES THRU...BUT CHC
OF ANY VSBY RESTRICTIONS WITH PRECIP IS VERY LOW. AS THE COLD FRONT
MOVES IN FROM THE NORTH DURING THE EARLY AFTERNOON...WINDS TURN FROM
SOUTHWEST TO NORTHEAST AROUND 18 UTC. LATEST GUIDANCE SHOWS CIGS
WITH THE FRONT TO REMAIN VFR...BUT COULD BE LOW VFR CAUSING SOME
RESTRICTIONS. CIGS LIFTING ABOUT TO AROUND 7-8KFT DURING THE LATE
EVENING HOURS. WINDS WILL AVERAGE AROUND 8KTS BEHIND THE FRONT.
SHOWERS AND TSTMS WILL INCREASE ALONG THE FRONT THIS AFTN...BUT THAT
SHOULD BE AFTER IT MOVES SOUTH OF THE AIRFIELD.
ELSEWHERE...SHOWERS CONTINUE OVER NORTHERN GA AND THE NWRN UPSTATE
THIS MORNING. CIGS WILL LOWER SOME THIS MORNING...BUT PROBABLY NOT
LOWER THAN ABOUT 5KFT. SCT TSTMS WILL DEVELOP IN THE VICINITY OF THE
UPSTATE TAF SITES BY MID AFTN WITH CIGS FALLING TO 3-4KFT. MEANWHILE
DRIER AIR WILL WORK INTO KHKY WITH GRADUALLY RISING CIGS. BY EARLY
EVENING THE STORMS WILL MOVE SOUTH OF ALL THE AIRFIELDS. DRIER LOW
LEVEL AIR WILL BRING CIGS UP TO AROUND 5KFT FEET AT ALL SOUTHERN TAF
SITES THROUGH THE NIGHT.
OUTLOOK...COLD AIR DAMMING MAY RESTRICT CIGS WEDNESDAY NIGHT INTO
FRIDAY. MORNING RESTRICTIONS IN FOG AND STRATUS ARE POSSIBLE EARLY
SATURDAY AND SUNDAY WITH FAIR CONDITIONS EXPECTED DURING THE
AFTERNOONS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY/RWH
SHORT TERM...NED
LONG TERM...DEO
AVIATION...MCAVOY/RWH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
638 AM EST WED DEC 5 2012
.SYNOPSIS...
A COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE AREA TODAY AND REACH
THE SOUTH CAROLINA COAST THIS EVENING. HIGH PRESSURE WILL RETURN
THURSDAY AND FRIDAY. EXPECT THIS HIGH TO BECOME CENTERED OFF THE
EAST COAST WHICH WILL RESULT IN A STRONG SOUTHERLY FLOW OF WARM AND
MOIST AIR OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 635 AM EST WEDNESDAY...LOCAL RADAR...SFC OBS AND IFLOWS
OBSERVATIONS SHOW THAT SHOWERS HAVE INCREASED OVER THE NC AND NE GA
MTNS THE PAST FEW HOURS. THIS IS IN LINE WITH THE FORECAST. SOME
LIGHTER SHOWERS ARE ALSO FALLING OVER THE FOOTHILLS AND
PIEDMONT...BUT THEY ARE LIGHTER. A MORE CONCENTRATED AREA OF RAIN
HAS DEVELOPED OVER NRN GA AND SHOULD MOVE INTO RABUN...HABERSHAM AND
OCONEE COUNTIES OVER THE NEXT COUPLE HOURS.
AS OF 435 AM EST WEDNESDAY...ADJUSTED MIN TEMPS UP A COUPLE DEGREES
BASED ON INCREASING CLOUD COVER. PATCHY LIGHT RAIN AND A FEW HEAVIER
SHOWERS ARE DEVELOPING OVER WRN NC AND ALONG THE TN LINE. THIS LINES
UP FAIRLY WELL WITH THE GRADUALLY INCREASING POP TREND IN THE GRIDS.
PREVIOUS DISCUSSION...
A STRONG TROUGH WILL MOVE ACROSS THE NEW ENGLAND STATES
TODAY...WHILE A CUT-OFF SRN STREAM LOW DRIFTS DOWN INTO THE NRN GULF
OF MEXICO. A SFC FRONT WILL STALL OVER THE MOUNTAINS THIS
MORNING...THOUGH HEIGHT RISES ACROSS THE MID-ATLANTIC STATES WILL
SEND THE THE FRONT SURGING SOUTHWARD A LITTLE LATER IN THE DAY. WEAK
H8 FRONTOGENESIS WILL ACCOMPANY THE BNDRY...THOUGH THE DEEP LAYER
FORCING LOOKS WEAK. LOW LEVEL CONVERGENCE WILL POOL MOISTURE AHEAD
OF THE FRONT AND MOST OF THE NUMERICAL MODELS DEVELOP ENOUGH
INSTABILITY OVER THE UPSTATE...SRN NC MTNS AND NE GA TO SUPPORT
SHOWERS AND EVEN A FEW TSTMS THIS AFTERNOON. THE NAM IS A LITTLE
FASTER THAN THE GFS...WHILE THE RUC IS A HAIR SLOWER THAN EITHER
MODEL. I HAVE EXTENDED THUNDER CHANCES UP ACROSS THE SRN NC MTNS AS
I DON/T SEE THE BNDRY MAKING IT THROUGH THESE AREAS UNTIL LATE AFTN.
IN FACT...THE FRONT WILL MAKE IT THROUGH CHARLOTTE AND THE NE
UPSTATE BEFORE THE CLEARS THE ESCARPMENT. CONVECTION IS EXPECTED TO
THEN SETTLE SOUTHWARD ACROSS THE UPSTATE AND NE GA. ATTM I DON/T
EXPECT ANYTHING SEVERE OWING TO THE MOIST MID-LEVELS AND WEAK LAPSE
RATES.
HIGH PRESSURE WILL CONTINUE TO RIDGE DOWN THE EAST SLOPES OF THE
APPALACHIANS TONIGHT. THE 1031 MB SFC HIGH CENTERS OVER PENNSYLVANIA
QUALIFIES AS A CLASSICAL COLD AIR DAMMING...AND IT WILL BRING A GOOD
INFLUX AND COOL AND DRY LOW LEVEL AIR INTO THE REGION. SKIES SHOULD
CLEAR OVERNIGHT ACROSS MUCH OF NORTH CAROLINA...AT LEAST NORTH OF A
LINE FROM CHARLOTTE TO ASHEVILLE...WHILE SKIES REMAIN CLOUDY OVER
THE UPSTATE AND NE GA ATOP THE DAMMING AIRMASS. THE MOISTURE LOOKS
SHALLOW AND PCPN CHANCES WILL BE LOW AND CONFINED TO THE SRN MOST
ZONES.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 245 AM WEDNESDAY...SHORT RANGE MODELS BEGIN THE SHORT RANGE
PERIOD...12Z THURS...IN GOOD AGREEMENT WITH THE POSITION OF THE BACK
DOOR COLD FRONT ACROSS THE UPPER SAVANNAH RIVER VALLEY AND SFC HIGH
PRESSURE CENTERED OVER THE MID ATLANTIC AND NEW ENGLAND STATES. AT
H5...A TROF IS EXPECTED TO PIVOT OVER THE NRN GULF...SUPPORTING THE
FORMATION OF A WEAK LOW NEAR THE MISSISSIPPI DELTA DURING THE
DAYLIGHT HOURS. AT 295K...WEAK ISENTROPIC LIFT IS EXPECTED TO
CONTINUE OVER NE GA AND THE WESTERN CAROLINAS THROUGH THURSDAY.
FORECAST SOUNDINGS INDICATE THAT THE CLOUD LAYER MAY RANGE BETWEEN
5-10 KFT...WITH LLVL NE FLOW. LLVL LIFT AND THICK MOISTURE MAY YIELD
PATCHES OF -RA TO SPRINKLES...BUT MEASURABLE QPF SEEMS UNLIKELY.
HOWEVER...GIVEN THE THICK CLOUD COVER FROM SUNRISE TO SUNSET AND
PERSISTENT NE FLOW...HIGH TEMPERATURES SHOULD VERIFY FAIRLY UNIFORM
ACROSS THE CWA ON THURSDAY. I WILL POPULATE TEMPS FROM THE NAM 2M
TEMPS...YIELDING HIGH TEMPERATURE FORECAST FROM THE MID 50S ALONG
AND EAST OF I-85 TO NEAR 50 ALONG AND NORTH OF I-40.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE CENTER OF HIGH PRESSURE SHOULD
SLIDE OVER THE WESTERN ATLANTIC AS LOW PRESSURE DEVELOPS OVER THE
CENTRAL PLAIN AND MID MISSISSIPPI RIVER VALLEY. FORECAST SOUNDINGS
INDICATE THAT CLOUD COVER WILL REMAIN PLENTIFUL ACROSS THE CWA
THROUGH THE PERIOD. LLVL LIFT AND SYNOPTIC SCALE FORCING WILL REMAIN
VERY WEAK...SUPPORTING MAINLY SCHC POPS ACROSS THE MTNS AND
FOOTHILLS. TEMPERATURES WILL GRADUALLY MODERATE THROUGH THE
PERIOD...REMAINING WELL ABOVE NORMAL AT NIGHT AND NEAR NORMAL FOR
FRIDAY HIGHS.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 240 AM WEDNESDAY...THE MEDIUM RANGE WILL BE A PERIOD OF TIME
UNDER THE INFLUENCE OF A SOUTHERLY FLOW PRIOR TO THE ARRIVAL OF A
COLD FRONT IN THE FIRST HALF OF THE WEEK. HIGH PRESSURE WILL BE
CENTERED NEAR BERMUDA WITH A SOUTHERLY FLOW WHICH WILL CONTINUE
THROUGH THE WEEKEND AND TO START THE WEEK AHEAD OF THE FRONT. ALL
MODELS AGREE ON THE GENERAL WEEKEND SCENARIO WITH THE WARMTH AND
MOISTURE ADVECTION AND SLIGHT TO LOW CHANCE POPS FROM NE GA TO
ACROSS THE WESTERN CAROLINAS.
THE GFS MODEL IS MOST PROGRESSIVE WITH THE FRONT MOVING EAST OF OUR
AREA MONDAY EVENING. SOME CAPE VALUES OF AROUND 20 ON GFS SATURDAY
AFTERNOON IN THE NC MTNS THEN RISE TO AROUND 160 OVER THE SMOKIES
SUNDAY AFTERNOON. IT ALL COMES TOGETHER ON THE GFS MONDAY AFTERNOON
WITH CAPES OF AROUND 160 FROM NE GA TO THE NC MTNS AND 850MB WIND 40
TO 50 KTS AND 700MB WIND 55 TO 65 KTS.
THE LATEST ECMWF WHICH JUST ARRIVED IS CLOSER TO THE GFS NOW IN
TIMING AND HAS THE FRONT EAST OF OUR AREA EARLY TUESDAY MORNING.
EARLIER RUN HAD THE FRONT ARRIVING EARLY TUESDAY AFTERNOON. WIND
SPEEDS ARE COMPARABLE TO THE GFS AND NOW SINCE THE ECMWF FRONT
ARRIVES EARLIER THE CAPES ARE HIGHER AS WELL. ECMWF HAS CAPES OF
400 TO 600 MONDAY AFTERNOON ALONG THE I-85 CORRIDOR. SINCE BOTH ARE
IN BETTER AGREEMENT...WILL INCREASE POPS LATE MONDAY AND THEN
DECREASE POPS TUESDAY AS THE FRONT SHOULD BE OUT OF THE AREA TO
EAST.
TEMPERATURES WILL BE 10 OR MORE DEGREES ABOVE NORMAL AHEAD OF THE
FRONT AND THEN STARTING A COOLING TREND BEHIND THE FRONT ON DAY 7
TUESDAY.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...A CIG UP AROUND 10KFT SHOULD LOWER TO 5-6KFT OVER THE NEXT
FEW HOURS. A FEW LIGHT SHOWERS WILL PERSIST AROUND THE AIRFIELD THIS
MORNING...THOUGH FOR NOW I THINK VCSH CAN HANDLE IT. A COLD FRONT
WILL MOVE IN FROM THE NORTH DURING THE EARLY AFTERNOON...TURNING
WINDS FROM SOUTHWEST TO NORTHEAST AROUND 18 UTC. CIGS WITH THE FRONT
ARE EXPECTED TO DROP INTO THE MVFR RANGE FOR A FEW HOURS...WITH CIGS
LIFTING ABOUT TO AROUND 7-8KFT DURING THE LATE EVENING HOURS. WINDS
WILL AVERAGE AROUND 8KTS BEHIND THE FRONT. SHOWERS AND TSTMS WILL
INCREASE ALONG THE FRONT THIS AFTN...BUT THAT SHOULD BE AFTER IT
MOVES SOUTH OF THE AIRFIELD.
ELSEWHERE...SHOWERS HAVE BEEN GRADUALLY INCREASING OVER THE
MOUNTAINS AND NORTHERN GA THIS MORNING. PREVAILING SHRA HAVE BEEN
ADDED TO KAVL WITH VCSH AT THE OTHER AIRFIELDS. CIGS WILL LOWER SOME
THIS MORNING...BUT PROBABLY NOT LOWER THAN ABOUT 5KFT. SCT TSTMS
WILL DEVELOP IN THE VICINITY OF THE UPSTATE TAF SITES BY MID AFTN
WITH CIGS FALLING TO 3-4KFT. MEANWHILE DRIER AIR WILL WORK INTO KHKY
WITH GRADUALLY RISING CIGS. BY EARLY EVENING THE STORMS WILL MOVE
SOUTH OF ALL THE AIRFIELDS. DRIER LOW LEVEL AIR WILL BRING CIGS UP
TO AROUND 5KFT FEET AT ALL SOUTHERN TAF SITES THROUGH THE NIGHT.
OUTLOOK...COLD AIR DAMMING MAY RESTRICT CIGS WEDNESDAY NIGHT INTO
FRIDAY. MORNING RESTRICTIONS IN FOG AND STRATUS ARE POSSIBLE EARLY
SATURDAY AND SUNDAY WITH FAIR CONDITIONS EXPECTED DURING THE
AFTERNOONS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY
SHORT TERM...NED
LONG TERM...DEO
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
726 AM CST WED DEC 5 2012
.AVIATION...
CIGS ARE ERODING JUST BEFORE THEY GET TO THE TAF SITES AND HAVE
REMOVED THEIR MENTION.
.../PREVIOUS AVIATION DISCUSSION/...
PRIMARY FORECAST CONCERN IS THE MVFR CIG MOVING TOWARD THE TAF
SITES FROM THE EAST. RAP HAS FINALLY PICKED UP ON THESE CLOUDS AND
FORECAST APPEARS REASONABLE. CIGS WILL LIKELY MAKE IT TO KDAL
AND KACT THIS MORNING...BUT SHOULD BEGIN TO DISPERSE AS THEY MOVE
WEST OF THE 35 CORRIDOR. OBVIOUSLY THIS WILL HAVE TO BE WATCHED...
BUT FOR NOW HAVE INCLUDED A TEMPO BKN020 FROM MID-LATE MORNING FOR
DFW/ACT AND PREVAILED BKN020 AT DAL. PROVIDED CIGS BREAK UP WITH
SOME HEATING TODAY...VFR SHOULD PREVAIL THIS AFTERNOON/EVENING AT
ALL TAF SITES WITH NORTH WINDS 5-10KT. OTHERWISE WILL NEED TO KEEP
AN EYE ON FOG POTENTIAL TONIGHT. WACO HAS THE BEST CHANCE FOR FOG
AND WILL INTRODUCE MVFR VSBY AFTER 9Z TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 349 AM CST WED DEC 5 2012/
TODAY WILL BE A COOLER DAY BEHIND YESTERDAY/S COLD FRONT.
TEMPERATURES WILL CLIMB INTO THE 60S AND LOWER 70S THIS AFTERNOON.
SOME OF THE COOLEST AFTERNOON TEMPERATURES WILL LIKELY BE FOUND
OVER THE SOUTHEASTERN COUNTIES WHERE CLOUD COVER MAY PERSIST FOR
MUCH OF THE DAY. TONIGHT...THE RETURN OF SOUTHERLY WINDS IN THE
LOWER LEVELS OF THE ATMOSPHERE WILL BRING LOW-LEVEL MOISTURE
SURGING NORTH OVER THE REGION. HOWEVER...WITH THE SURFACE WIND
SPEEDS REMAINING BELOW 5 KTS...FOG COULD LIKELY DEVELOP OVER A
GOOD PORTION OF THE AREA. FOR NOW...HAVE HIGHLIGHTED ROUGHLY THE
SOUTHEASTERN HALF OF THE CWA WITH A MENTION OF FOG IN THE
ZONES...AND THE BEST CHANCES FOR WIDESPREAD FOG WILL BE SOUTH OF A
LINE FROM GOLDTHWAITE TO CANTON. IT IS POSSIBLE AREAS OF DENSE FOG
COULD DEVELOP AND WILL CONTINUE TO ASSESS THIS POTENTIAL TODAY. A
QUICK WARMUP IS EXPECTED TOMORROW AS THE UPPER LEVEL PATTERN
RETURNS TO NEAR ZONAL FLOW AND SOUTHWEST WINDS AT H850 BRING
WARMER TEMPERATURES OVER THE REGION. TEMPERATURES TOMORROW WILL BE
IN THE 70S REGION-WIDE.
A FRONT THAT WILL DEVELOP TONIGHT OVER THE NORTHERN ROCKIES WILL
PUSH INTO THE NORTHWEST QUADRANT OF NORTH TEXAS ON FRIDAY. THERE
IS CONSIDERABLE UNCERTAINTY AMONGST THE MODELS ON HOW EACH HANDLES
THE FRONT BUT THE OVERALL IMPACTS ARE RELATIVELY MINIMAL. THE GFS
AND NAM PUSH THIS WEAK FRONT THROUGH MOST OF THE CWA WHILE THE
ECMWF AND GEM HANG THE FRONT OVER THE NORTHERN HALF OF THE CWA.
GIVEN THE FORECASTED MODIFIED AIR BEHIND THIS FRONT AND THE UPPER
LEVEL ZONAL FLOW PATTERN...WILL SIDE WITH THE ECMWF/GEM FOR NOW
AND STALL THE FRONT GENERALLY NORTH OF I-20 FRIDAY NIGHT AND
SATURDAY. THERE IS A SLIGHT CHANCE FOR RAIN EAST OF HIGHWAY 75 AND
INTERSTATE 45 FRIDAY AFTERNOON AND NIGHT AS THE FRONT MOVES IN
AND A WEAK SHORTWAVE MOVES OVER THE REGION. PWATS WILL BE HIGHEST
OVER THE EASTERN COUNTIES BUT APPRECIABLE RAINFALL IS NOT
EXPECTED. WILL ONLY MENTION SHOWERS FOR NOW BUT AN ISOLATED
THUNDERSTORM IS POSSIBLE.
THE FORECAST FOR FRIDAY THROUGH SATURDAY NIGHT IS A LITTLE COMPLICATED
BY THE MODEL DISCREPANCIES WITH THE FRONT. ASIDE FROM THE
DIFFERENCE IN FRONTAL POSITION...THEY ALSO DIFFER IN CLOUD COVER
AND TEMPERATURES. WILL KEEP AREAS AHEAD OF THE FRONT PARTLY TO
MOSTLY CLOUDY WITH HIGHS IN THE MID TO UPPER 70S AND LOWS IN THE
50S AND 60S. BEHIND THE FRONT...TEMPERATURES WILL BE SLIGHTLY
LOWER WITH HIGHS IN THE LOWER 70S AND LOWS IN THE 40S TO AROUND 50
DEGREES.
THE BIG STORY IN THE FORECAST CONTINUES TO BE THE CANADIAN FRONT
THAT WILL COME SCREAMING THROUGH THE REGION EARLY NEXT WEEK. THE
TIMING OF THE FRONT TONIGHT IS FASTER WITH AN ARRIVAL NOW ON
SUNDAY. THE ECMWF IS SLIGHTLY SLOWER WITH THE FRONT THAN THE GFS
AND GEM AND WILL SIDE WITH THE GFS/GEM FOR NOW AS THESE FRONTS
TYPICALLY DO ARRIVE FASTER. FORECASTED HIGH TEMPERATURES ON SUNDAY
WILL BE REACHED EARLY IN THE DAY WITH THE FRONT ARRIVING DURING
THE MORNING HOURS. THE FORECAST SOUNDINGS DO NOT LOOK FAVORABLE
FOR ANY HOPE OF DECENT RAIN WHEN THE FRONT COMES THROUGH. THE
SOUNDINGS ARE PRETTY DRY WITH PWATS BELOW AN INCH...EXCEPT FOR IN
THE SOUTHEASTERN COUNTIES WHERE PWATS ARE 1-1.25 INCHES. HAVE
POPS SUNDAY AFTERNOON OVER ROUGHLY THE EASTERN 2/3RDS OF THE
CWA...THEN OVER THE FAR SOUTHERN COUNTIES ON SUNDAY NIGHT AS THE
FRONT CONTINUES TO PUSH SOUTH. AFTER THAT...A RAPID DRYING TREND
IS EXPECTED AS THE FRONT PUSHES INTO THE GULF OF MEXICO AND
FORECAST SOUNDINGS QUICKLY DRY OUT THE ATMOSPHERIC COLUMN. THE
ECMWF IS FAIRLY AGGRESSIVE WITH POST- FRONTAL PRECIPITATION
OCCURRING SUNDAY NIGHT BUT WILL KEEP THE FORECAST DRY BEHIND THE
FRONT DUE TO THE QUICK DRYING TREND ADVERTISED BY THE OTHER
MODELS. IF THERE WAS TO BE SOME POST- FRONTAL PRECIP...THE ECMWF
SUGGESTS IT WOULD BE A COLD RAIN IN OUR AREA. HOPEFULLY WE WILL
REACH SOME BETTER MODEL AGREEMENT WITH THE TIMING AND PRECIP BY
THE WEEKEND BUT WITH THE LATEST MODEL RUNS...THE CHANCE FOR
BENEFICIAL RAIN LOOKS PRETTY BLEAK.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 68 49 75 55 76 / 0 0 0 5 10
WACO, TX 70 45 76 54 77 / 0 0 0 5 10
PARIS, TX 66 43 71 52 73 / 0 0 0 5 20
DENTON, TX 68 45 74 54 74 / 0 0 0 5 10
MCKINNEY, TX 67 44 73 54 73 / 0 0 0 5 10
DALLAS, TX 68 50 75 56 77 / 0 0 0 5 10
TERRELL, TX 66 46 73 55 74 / 0 0 0 5 10
CORSICANA, TX 65 49 74 56 76 / 0 0 0 5 10
TEMPLE, TX 71 45 76 54 78 / 0 0 0 5 10
MINERAL WELLS, TX 68 42 78 50 73 / 0 0 0 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
527 AM CST WED DEC 5 2012
.AVIATION...
PRIMARY FORECAST CONCERN IS THE MVFR CIG MOVING TOWARD THE TAF
SITES FROM THE EAST. RAP HAS FINALLY PICKED UP ON THESE CLOUDS AND
FORECAST APPEARS REASONABLE. CIGS WILL LIKELY MAKE IT TO KDAL
AND KACT THIS MORNING...BUT SHOULD BEGIN TO DISPERSE AS THEY MOVE
WEST OF THE 35 CORRIDOR. OBVIOUSLY THIS WILL HAVE TO BE WATCHED...
BUT FOR NOW HAVE INCLUDED A TEMPO BKN020 FROM MID-LATE MORNING FOR
DFW/ACT AND PREVAILED BKN020 AT DAL. PROVIDED CIGS BREAK UP WITH
SOME HEATING TODAY...VFR SHOULD PREVAIL THIS AFTERNOON/EVENING AT
ALL TAF SITES WITH NORTH WINDS 5-10KT. OTHERWISE WILL NEED TO KEEP
AN EYE ON FOG POTENTIAL TONIGHT. WACO HAS THE BEST CHANCE FOR FOG
AND WILL INTRODUCE MVFR VSBY AFTER 9Z TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 349 AM CST WED DEC 5 2012/
TODAY WILL BE A COOLER DAY BEHIND YESTERDAY/S COLD FRONT.
TEMPERATURES WILL CLIMB INTO THE 60S AND LOWER 70S THIS AFTERNOON.
SOME OF THE COOLEST AFTERNOON TEMPERATURES WILL LIKELY BE FOUND
OVER THE SOUTHEASTERN COUNTIES WHERE CLOUD COVER MAY PERSIST FOR
MUCH OF THE DAY. TONIGHT...THE RETURN OF SOUTHERLY WINDS IN THE
LOWER LEVELS OF THE ATMOSPHERE WILL BRING LOW-LEVEL MOISTURE
SURGING NORTH OVER THE REGION. HOWEVER...WITH THE SURFACE WIND
SPEEDS REMAINING BELOW 5 KTS...FOG COULD LIKELY DEVELOP OVER A
GOOD PORTION OF THE AREA. FOR NOW...HAVE HIGHLIGHTED ROUGHLY THE
SOUTHEASTERN HALF OF THE CWA WITH A MENTION OF FOG IN THE
ZONES...AND THE BEST CHANCES FOR WIDESPREAD FOG WILL BE SOUTH OF A
LINE FROM GOLDTHWAITE TO CANTON. IT IS POSSIBLE AREAS OF DENSE FOG
COULD DEVELOP AND WILL CONTINUE TO ASSESS THIS POTENTIAL TODAY. A
QUICK WARMUP IS EXPECTED TOMORROW AS THE UPPER LEVEL PATTERN
RETURNS TO NEAR ZONAL FLOW AND SOUTHWEST WINDS AT H850 BRING
WARMER TEMPERATURES OVER THE REGION. TEMPERATURES TOMORROW WILL BE
IN THE 70S REGION-WIDE.
A FRONT THAT WILL DEVELOP TONIGHT OVER THE NORTHERN ROCKIES WILL
PUSH INTO THE NORTHWEST QUADRANT OF NORTH TEXAS ON FRIDAY. THERE
IS CONSIDERABLE UNCERTAINTY AMONGST THE MODELS ON HOW EACH HANDLES
THE FRONT BUT THE OVERALL IMPACTS ARE RELATIVELY MINIMAL. THE GFS
AND NAM PUSH THIS WEAK FRONT THROUGH MOST OF THE CWA WHILE THE
ECMWF AND GEM HANG THE FRONT OVER THE NORTHERN HALF OF THE CWA.
GIVEN THE FORECASTED MODIFIED AIR BEHIND THIS FRONT AND THE UPPER
LEVEL ZONAL FLOW PATTERN...WILL SIDE WITH THE ECMWF/GEM FOR NOW
AND STALL THE FRONT GENERALLY NORTH OF I-20 FRIDAY NIGHT AND
SATURDAY. THERE IS A SLIGHT CHANCE FOR RAIN EAST OF HIGHWAY 75 AND
INTERSTATE 45 FRIDAY AFTERNOON AND NIGHT AS THE FRONT MOVES IN
AND A WEAK SHORTWAVE MOVES OVER THE REGION. PWATS WILL BE HIGHEST
OVER THE EASTERN COUNTIES BUT APPRECIABLE RAINFALL IS NOT
EXPECTED. WILL ONLY MENTION SHOWERS FOR NOW BUT AN ISOLATED
THUNDERSTORM IS POSSIBLE.
THE FORECAST FOR FRIDAY THROUGH SATURDAY NIGHT IS A LITTLE COMPLICATED
BY THE MODEL DISCREPANCIES WITH THE FRONT. ASIDE FROM THE
DIFFERENCE IN FRONTAL POSITION...THEY ALSO DIFFER IN CLOUD COVER
AND TEMPERATURES. WILL KEEP AREAS AHEAD OF THE FRONT PARTLY TO
MOSTLY CLOUDY WITH HIGHS IN THE MID TO UPPER 70S AND LOWS IN THE
50S AND 60S. BEHIND THE FRONT...TEMPERATURES WILL BE SLIGHTLY
LOWER WITH HIGHS IN THE LOWER 70S AND LOWS IN THE 40S TO AROUND 50
DEGREES.
THE BIG STORY IN THE FORECAST CONTINUES TO BE THE CANADIAN FRONT
THAT WILL COME SCREAMING THROUGH THE REGION EARLY NEXT WEEK. THE
TIMING OF THE FRONT TONIGHT IS FASTER WITH AN ARRIVAL NOW ON
SUNDAY. THE ECMWF IS SLIGHTLY SLOWER WITH THE FRONT THAN THE GFS
AND GEM AND WILL SIDE WITH THE GFS/GEM FOR NOW AS THESE FRONTS
TYPICALLY DO ARRIVE FASTER. FORECASTED HIGH TEMPERATURES ON SUNDAY
WILL BE REACHED EARLY IN THE DAY WITH THE FRONT ARRIVING DURING
THE MORNING HOURS. THE FORECAST SOUNDINGS DO NOT LOOK FAVORABLE
FOR ANY HOPE OF DECENT RAIN WHEN THE FRONT COMES THROUGH. THE
SOUNDINGS ARE PRETTY DRY WITH PWATS BELOW AN INCH...EXCEPT FOR IN
THE SOUTHEASTERN COUNTIES WHERE PWATS ARE 1-1.25 INCHES. HAVE
POPS SUNDAY AFTERNOON OVER ROUGHLY THE EASTERN 2/3RDS OF THE
CWA...THEN OVER THE FAR SOUTHERN COUNTIES ON SUNDAY NIGHT AS THE
FRONT CONTINUES TO PUSH SOUTH. AFTER THAT...A RAPID DRYING TREND
IS EXPECTED AS THE FRONT PUSHES INTO THE GULF OF MEXICO AND
FORECAST SOUNDINGS QUICKLY DRY OUT THE ATMOSPHERIC COLUMN. THE
ECMWF IS FAIRLY AGGRESSIVE WITH POST- FRONTAL PRECIPITATION
OCCURRING SUNDAY NIGHT BUT WILL KEEP THE FORECAST DRY BEHIND THE
FRONT DUE TO THE QUICK DRYING TREND ADVERTISED BY THE OTHER
MODELS. IF THERE WAS TO BE SOME POST- FRONTAL PRECIP...THE ECMWF
SUGGESTS IT WOULD BE A COLD RAIN IN OUR AREA. HOPEFULLY WE WILL
REACH SOME BETTER MODEL AGREEMENT WITH THE TIMING AND PRECIP BY
THE WEEKEND BUT WITH THE LATEST MODEL RUNS...THE CHANCE FOR
BENEFICIAL RAIN LOOKS PRETTY BLEAK.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 68 49 75 55 76 / 0 0 0 5 10
WACO, TX 70 45 76 54 77 / 0 0 0 5 10
PARIS, TX 66 43 71 52 73 / 0 0 0 5 20
DENTON, TX 68 45 74 54 74 / 0 0 0 5 10
MCKINNEY, TX 67 44 73 54 73 / 0 0 0 5 10
DALLAS, TX 68 50 75 56 77 / 0 0 0 5 10
TERRELL, TX 66 46 73 55 74 / 0 0 0 5 10
CORSICANA, TX 65 49 74 56 76 / 0 0 0 5 10
TEMPLE, TX 71 45 76 54 78 / 0 0 0 5 10
MINERAL WELLS, TX 68 42 78 50 73 / 0 0 0 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
341 PM MST WED DEC 5 2012
.SHORT TERM...MODERATE WESTERLY FLOW CURRENTLY ALOFT ACROSS
COLORADO WITH DECENT PRESSURE FALLS AHEAD OF APPROACHING MID LEVEL
TROUGH. WINDS A BIT GUSTY ACROSS MOUNTAINS AND FOOTHILLS AS WELL
AS WESTERN SECTIONS OF URBAN CORRIDOR. 1500M GJT-DEN PRESSURE
GRADIENTS CURRENTLY AT 8.09 MB...HAS BEEN INCREASING SINCE 20Z.
LATEST RUC CROSS SECTIONS SHOWING CROSS MOUNTAIN FLOW 55 KTS AT
MOUNTAIN TOP THROUGH 02Z THEN DECREASING TO AROUND 40 KTS BY 04Z.
SO WINDS TO REMAIN GUSTY INTO THE EVENING HOURS ESPECIALLY ACROSS
MOUNTAINS AND ALONG FOOTHILLS...BEFORE DECREASING DURING THE
EVENING. OTHERWISE...MOISTURE TO CONTINUE TO INCREASE THROUGH THE
EVENING AS TROUGH MOVES INTO THE GREAT BASIN. THE DEEPER AND MORE
SUBSTANTIAL MOISTURE WILL BEGIN ADVECTING INTO THE MOUNTAINS AFTER
00Z. COMBINATION OF SOME COLDER AIR ALOFT AND INCREASING LIFT
WILL HELP WITH PRECIPITATION DEVELOPMENT ACROSS MOUNTAINS.
POTENTIAL FOR SOME BANDED PRECIPITATION ACROSS THE NORTHERN
MOUNTAINS AFTER MIDNIGHT...WILL KEEP THE HIGHER POPS THERE. SYSTEM
INITIALLY FAIRLY WARM...SO SNOW ACCUMULATIONS TO BE LIGHT. ACROSS
PLAINS...STILL SOME THREAT FOR LIGHT RAIN NEAR THE WYOMING BORDER
WHERE SOME BANDED PRECIP COULD OCCUR. OTHERWISE...THINGS LOOK DRY
OVERNIGHT. MODELS STILL SHOWING WEAK FRONT MOVING ACROSS AREA
AFTER MIDNIGHT WITH WINDS SHIFTING TO THE NORTH. SOME WEAK UPSLOPE
TO DEVELOP BEHIND FRONT...THOUGH 12Z MODEL CROSS SECTIONS SHOW
FAIRLY DRY LOW LEVELS. ON THURSDAY...MODEL CROSS SECTIONS SHOW
DECENT MOUNTAIN OROGRAPHICS WITH GOOD MOISTURE. THOUGH MOST OF THE
LIFT MOVES ACROSS WYOMING...THERE IS ENOUGH LIFT ACROSS THE
MOUNTAINS DURING THE MORNING TO HELP WITH SNOWFALL. THE LIKELY
POPS STILL LOOKING REASONABLE WITH UP TO 2 INCHES POSSIBLE...
MAINLY WEST FACING SLOPES. BY AFTERNOON...MODELS SHOW OROGRAPHICS
WEAKENING AS LIFT MOVES EAST OF THE AREA...SO SNOW CHANCES TO
DECREASE DURING THE AFTERNOON. ACROSS PLAINS...LIFT TO MOVE ACROSS
AREA DURING THE MORNING AS WEAK UPSLOPE CONTINUES. COULD SEE SOME
PRECIPITATION THROUGH 18Z...THOUGH LIFT AND UPSLOPE NOT VERY
IMPRESSIVE. LATEST MODELS CONTINUE TO SHOW SOME LIGHT QPF...SEEMS
TO BE OVERDONE. ALSO TEMPERATURES LOOK TO BE WARM ENOUGH FOR
RAIN...EXCEPT PERHAPS ALONG PALMER DIVIDE AND CHEYENNE RIDGE.
AFTER 18Z LIFT IS EAST OF AREA WITH SUBSIDENCE OVERHEAD. THIS
SHOULD NEGATE ANY PRECIP CHANCES. COOLER AIRMASS WILL BE OVER AREA
WITH TEMPERATURES ROUGHLY 15 TO 20 DEGREES COLDER THAN TODAY`S
READINGS ACROSS PLAINS WITH HIGHS IN THE UPPER 40S AND LOWER 5OS.
THIS IS STILL ABOVE NORMAL.
.LONG TERM...A WEST-NORTHWEST FLOW ALOFT WILL PREVAIL THURSDAY
NIGHT THROUGH SATURDAY. MOISTURE EMBEDDED IN THE FLOW ALOFT WILL
BRING SOME LIGHT OROGRAPHIC SNOW TO THE MOUNTAINS AT TIMES
THURSDAY NIGHT THROUGH FRIDAY NIGHT. LAPSE RATES ARE JUST ALRIGHT
AT 5-7 C/KM...SO EXPECT SNOWFALL AMOUNTS TO STAY ON THE LIGHT
SIDE. A COLD FRONT WILL PUSH SOUTH ACROSS EASTERN COLORADO FRIDAY.
THIS WILL LOWER TEMPERATURES ANOTHER 5-10 DEGREES FROM THURSDAYS
HIGHS.
MOISTURE WILL INCREASE LATE FRIDAY NIGHT AND SATURDAY AS AN UPPER
LEVEL TROUGH MOVES SOUTHEAST OVER THE UTAH WYOMING AREA. EXPECT
SNOW TO INCREASE SATURDAY OVER THE MOUNTAINS. AT THE SURFACE...A
STRONG COLD FRONT WILL DROP SOUTH ACROSS EASTERN COLORADO SATURDAY
AFTERNOON. THIS WILL BRING GUSTY NORTHERLY WINDS BEHIND. AS
UPSLOPE WINDS AND MOISTURE SET UP EXPECT SNOW TO START SATURDAY
AFTERNOON OR EVENING. THE UPPER LEVEL TROUGH AXIS WILL PASS OVER
COLORADO SATURDAY NIGHT. DOWNWARD MOTION BEHIND THE TROUGH WILL
BRING THE SNOW TO AN END LATE SATURDAY NIGHT OR SNOW MORNING.
MOST OF THE MODELS SHOW IT WILL DRY OUT QUICKLY BEHIND THE FRONT
ON SUNDAY. WILL KEEP LOW POPS IN FOR THE EARLY PART OF THE SUNDAY
FOR THE POSSIBLILITY OF LINGERING SNOW. IF THE CLOUDS CLEAR OUT
SUNDAY NIGHT IT MAY GET QUITE COLD AND BE THE COLDEST NIGHT SO
FAR THIS SEASON.
FOR EARLY NEXT WEEK...AN ACTIVE NORTHWEST FLOW ALOFT WILL
PREVAIL. WEAK DISTURBANCES WILL PASS OVER THE STATE IN THIS
PATTERN. LITTLE TOO EARLY TO GET A GOOD TIMING ON THESE
SYSTEMS...SO WILL BROADDRUSH LOW POPS FOR THE MOUNTAINS. AT THIS
TIME...IT APPEARS THESE WAVES WILL BE TOO WEAK TO BRING SNOW TO
THE FRONT RANGE AND WILL KEEP THE MENTION OF SNOW OUT OF THE
FORECAST. TEMPERATURES WILL REMAIN NEAR TO BELOW NORMAL EARLY NEXT
WEEK. WOULD EXPECT WINDY CONDITIONS AT TIMES ALONG THE EAST
SLOPES UNDER THIS PATTERN.
&&
.AVIATION...WINDS TO REMAIN GUSTY THROUGH 02Z WITH GUSTS TO 20
KTS POSSIBLE AT DEN AND APA...AND UP TO 30 KTS AT BJC. WINDS TO
CONTINUE TO SHIFT TO THE NORTHWEST. AFTER 02Z WINDS TO WEAKEN AS
GRADIENT WEAKENS THOUGH MAY STILL BE A BIT GUSTY AT BJC. WEAK
FRONT TO MOVE ACROSS THE PLAINS AFTER 06Z WITH WINDS BECOMING
NORTHEAST. CEILINGS TO LOWER TO AROUND 6000 FEET AGL BY 12Z WITH A
SLIGHT CHANCE OF LIGHT RAIN. CONDITIONS WILL REMAIN VFR ALTHOUGH
ILS CONDITIONS POSSIBLE DUE TO CEILINGS. CONDITIONS TO IMPROVE BY
18Z WITH LIGHT EAST TO SOUTHEAST WINDS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....MEIER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1012 AM MST WED DEC 5 2012
.UPDATE...
ISSUED AT 1008 AM MST WED DEC 5 2012
12Z NAM GUIDANCE SHOWING MUCH LESS PRECIP ACROSS FORECAST AREA
WITH THIS NEXT LITTLE DISTURBANCE EXCEPT FOR THE FLATTOPS AND
MOUNTAINS SURROUNDING STEAMBOAT SPRINGS. GFS SHOWS MORE AREAL
COVERAGE...TO INCLUDE UNCOMPAHGRE PLATEAU...BUT MUCH LESS QPF
AMOUNTS. HRRR AND EC ALSO FOLLOWING SUIT SO LOWERED POPS WITH THIS
UPDATE TO EXTREME NRN ZONES TODAY WITH ONSET OF PROLONGED PRECIP
STARTING AROUND 03Z THIS EVENING FOR THOSE AREAS MENTIONED ABOVE.
SNOWFALL AMOUNTS OF 2 TO 4 INCHES AT HIGHER ELEVATIONS WILL BE
COMMON FOR THE NORTHERN MOUNTAINS/FLATTOPS WHILE 1 TO 3 IS
EXPECTED FOR CENTRAL MOUNTAINS.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 300 AM MST WED DEC 5 2012
THE BEGINNING OF A PATTERN CHANGE STARTS TODAY AS THE UPPER LEVEL
LOW THAT HAS BEEN POSITIONED JUST OFF THE PACNW/B.C. COAST FOR QUITE
SOME TIME IS FINALLY PROGRESSING ACROSS CANADA THIS AFTERNOON. THIS
WILL PUSH ANOTHER PIECE OF ENERGY ACROSS OUR CWA THIS EVENING INTO
THURSDAY AFTERNOON. THIS MORNING WILL SEE SOME BREAKS IN THE CLOUD
COVER AS LOW LEVELS START OFF DRY...BUT THIS WILL ALL CHANGE THIS
AFTERNOON THROUGH THE EVENING AS CLOUDS INCREASE FROM THE
WEST...THICKEN AND LOWER AHEAD OF THE APPROACHING DISTURBANCE.
AFTERNOON TEMPERATURES WILL BE WARMER THAN YESTERDAYS WITH ABOVE
NORMAL READINGS IN THE MILD SOUTHWEST FLOW OUT AHEAD OF THE
APPROACHING DISTURBANCE.
THIS DISTURBANCE WILL BE MORE ROBUST THAN THE PAST FEW WEAK WAVES
THAT WERE EJECTED FROM THE PREVIOUSLY STATIONARY UPPER LOW. PLENTY
OF MOISTURE WILL BE IN PLACE WITH SPECIFIC HUMIDITIES IN THE 3.5 TO
4.0 G/KG RANGE AND SUFFICIENT SATURATION THROUGH THE DENDRITIC
LAYER...WHICH ACCORDING TO TIME HEIGHTS IS WELL ABOVE MOUNTAIN TOP
LEVEL AT AROUND 550MB OR 16.5KFT. TEMPS AT 700MB OR MOUNTAIN TOP
LEVEL IS AROUND -4C ACROSS THE NORTHERN MTNS AND AROUND 0C ACROSS
THE CENTRAL MTNS. THIS PUTS SNOW LEVELS AT AROUND 7 OR 8KFT. 700MB
WINDS WILL BE OUT OF THE WSW AT 25 TO 30 KTS MAINLY ACROSS THE
NORTHERN AND CENTRAL AREAS...SO THIS WILL FAVOR WEST-FACING SLOPES.
ISENTROPIC UPGLIDE IS EVIDENT AS WELL AS OMEGA WITH BETTER LIFT
ACROSS THE NORTHERN MOUNTAINS THAN THE CENTRAL MOUNTAINS. THE BEST
FORCING LOOKS TO OCCUR BETWEEN 09Z AND 15Z...RIGHT ON EITHER SIDE OF
SUNRISE THURSDAY MORNING. WHAT THIS ALL AMOUNTS TO IS ABOUT 3 TO 6
OVER THE FLATTOPS...ELKHEADS...AND PARK RANGES...WITH 2 TO 4 OVER
THE GRAND MESA. THESE AREAS LOOK FAVORED FOR BEST SNOW ACCUMS WITH
THE REST OF THE MOUNTAINS ABOVE 7 TO 8KFT RECEIVING 1 TO 3. LIGHT
RAIN SHOWERS ARE EXPECTED IN SOME NORTHERN AND CENTRAL VALLEYS WITH
SOME SNOW MIXING IN BUT NOT AMOUNTING TO MUCH AS THE GROUND IS
STILL FAIRLY WARM DUE TO RECENT ABOVE NORMAL TEMPS. INCREASED CLOUD
COVER SHOULD HELP TO KEEP TEMPS ABOVE FREEZING IN THE LOWER VALLEYS
TONIGHT.
BY THURSDAY AFTERNOON...SKIES WILL STILL REMAIN FAIRLY CLOUDY AS A
MOIST WESTERLY FLOW STAYS ON TOP OF US WITH SOME OROGRAPHIC SNOW
SHOWERS LIMITED TO THE HIGHER TERRAIN IN WESTERN COLORADO CLOSER AND
ALONG THE DIVIDE. TEMPERATURES WILL BE COOLER AND WILL NOT RECOVER
MUCH WITH A COOLING TREND EVIDENT AS THAT AIR FILTERS IN FROM THE
NORTHWEST THROUGH THE DAY. MORE DISCUSSION ON THIS IN THE LONG TERM
DISCUSSION BELOW.
.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 300 AM MST WED DEC 5 2012
MOIST WESTERLY FLOW WILL CONTINUE OVER THE REGION WITH SNOW
SHOWERS LINGERING OVER THE NORTHERN MOUNTAINS THROUGH FRIDAY. WITH
THE PERSISTENT NATURE OF THE SNOW SHOWERS...MAY SEE A FEW INCHES
OF ACCUMULATIONS THURSDAY NIGHT AND AGAIN FRIDAY...BUT BELOW
HIGHLIGHT CRITERIA. FOCUS WILL GENERALLY BE FROM VAIL PASS
NORTHWARD...WITH THE FLAT TOPS...PARK AND GORE RANGES FAVORED.
RISING HEIGHTS OFF THE WEST COAST WILL EVENTUALLY OPEN THE DOOR
FOR A MUCH COLDER SYSTEM TO SLIDE SOUTHEAST OUT OF SOUTHERN
ALASKA. THE NEW 00Z RUNS OF THE GFS AND ECMWF HAVE FLOPPED AGAIN
SHOWING A MORE PROGRESSIVE AND EVENTUALLY WEAK SYSTEM LATE
SATURDAY AND SUNDAY VERSUS DIGGING THE SYSTEM INTO THE SOUTHERN
GREAT BASIN. IN EITHER CASE...THE TREND IS TOWARD MUCH COOLER
WEATHER WITH MOUNTAIN SNOWFALL LIKELY TO CONTINUE THROUGH THE
WEEKEND...IN MOIST W AND EVENTUALLY NW FLOW. BEST FORCING ARRIVES
WITH THE COLDER AIR SATURDAY NIGHT AND EARLY SUNDAY AND THIS WOULD
BE THE TIMEFRAME FOR ANY POTENTIAL HIGHLIGHTS.
ANOTHER WAVE EJECTS OUT OF THE GULF ON MONDAY...BRINGING ANOTHER
CHANCE OF SNOW TO THE REGION BY TUESDAY...ALONG WITH A REINFORCING
SHOT OF COLDER AIR.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z NOON THURSDAY)
ISSUED AT 300 AM MST WED DEC 5 2012
SCATTERED TO BROKEN SKIES WILL CONTINUE TODAY THOUGH THEY WILL
BECOME PREDOMINATELY BROKEN TO OVERCAST AS THE DAY TURNS INTO
EVENING. THESE CLOUDS WILL VFR HOWEVER SO NO OPERATIONAL IMPACTS
ARE EXPECTED AT ANY AERODROMES. BY 06Z HOWEVER...AREAS NORTH OF
I-70 WILL SEE TIMES OF MVFR AND IFR UNDER HEAVIER RAIN/SNOW
SHOWERS AS VIS AND CIGS DROP. KVEL...KEGE...AND KASE WILL BE UNDER
THE GUN TONIGHT FOR THESE IFR CONDITIONS. CONDITIONS WILL IMPROVE
FROM 18Z ONWARDS TOMORROW.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...TGR
LONG TERM...JDC
AVIATION...TGR
AREA FORECAST DISCUSSION
NWS CARIBOU ME
258 PM EST WED DEC 5 2012
.SYNOPSIS...
A SECOND COLD FRONT WILL CROSS THE REGION THIS EVENING. HIGH
PRESSURE WILL BUILD ACROSS THE REGION ON THURSDAY AND THEN MOVE
EAST FRIDAY. LOW PRESSURE WILL APPROACH THE AREA SOUTHWEST ON SATURDAY.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
CHALLENGE WILL BE SNOW SHOWERS AND TEMPERATURES.
2ND COLD FRONT IS MOVING ACROSS THE NORTHERN 1/2 OF THE CWA ATTM
AND IS EXPECTED TO BE ACROSS DOWNEAST AND THE COAST LATER THIS
EVENING AND EARLY EVENING. SNOW SHOWERS MOVED ACROSS NORTHERN AND
WESTERN AREAS THIS AFTERNOON W/GUSTS UP TO 35 MPH AT KFVE. STRONG
LAPSE RATES AND CAA WILL LEAD TO GUSTY WINDS RIGHT INTO THE EVENING.
THE ASSOCIATED UPPER TROF IS SHOWN BY THE RUC AND CANADIAN
GEM(HANDLING THIS SET THE BEST) TO MOVE THROUGH THE REGION EARLY
TONIGHT. SOUNDINGS INDICATED LLVL RH IN PLACE AND SOME WEAK LIFT
TO CONTINUE W/ON AND OFF SNOW SHOWERS THROUGH 06Z. DECIDED TO KEEP
30% IN THERE UP THROUGH THIS TIME AND THEN THINGS DRY OUT
W/CLEARING EXPECTED. WINDS WILL STAY UP OVERNIGHT 10-20 MPH. THIS
WILL KEEP THE ATMOSPHERE MIXED KEEPING TEMPERATURES FROM DROPPING
OFF TOO FAR. MIDNIGHT CREW`S MINS LOOKED OK W/AN ADJUSTMENT UPWARD
TO ACCOUNT FOR THE WINDS. THIS MEANS UPPER TEENS NORTH TO AROUND
20 CENTRAL AREAS WHILE DOWNEAST AND THE COAST WILL SEE LOW/MID 20S.
THURSDAY WILL BE A SUNNY DAY BUT AT LEAST 15 DEGREES COLDER THAN
TODAY AS HIGH PRES BUILDS E AND COLD AIR IS IN PLACE. ONCE AGAIN,
MIDNIGHT CREW`S TEMPERATURES LOOKED FINE AND STAYED THE COURSE
W/UPPER 20S TO LOWER 30S NORTH WHILE MID 30S LOOK LIKE A GOOD FIT
FOR CENTRAL AND DOWNEAST. MUCH COLDER THURSDAY NIGHT AS HIGH PRES
SLIDES E AND OUR REGION GETS UNDER THE START OF WAA. THE
NUMERICAL MODELS TEND TO WARM THE LLVLS UP TO FAST W/THIS SETUP
AND STRONG INVERSION SETTING UP. ALSO, THE GUIDANCE APPEARS TO BE
TOO QUICK IN BRING HIGHER CLOUDS IN TOO FAST. THEREFORE, UNDERCUT
MINS THURSDAY NIGHT FROM WHAT THE MIDNIGHT CREW HAD BY SOME 3-5
DEGREES. THIS MEANS LOW/MID TEENS NORTH W/AROUND 20 FOR CENTRAL
AND DOWNEAST AREAS.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
HIGH PRESSURE MOVES EAST OF THE AREA ON FRIDAY WITH WARMER
SOUTHWEST FLOW AND PARTLY CLOUDY SKIES. MOISTURE INCREASES FRIDAY
NIGHT AND INTO SATURDAY AHEAD OF OUR NEXT SYSTEM, WITH CONTINUED
WARM AIR ADVECTION ALOFT. HOWEVER, MODELS HAVE BEEN IN VERY POOR
AGREEMENT ON THE DETAILS OF THIS SYSTEM. EITHER WAY, THOUGH,
PRECIP AMOUNTS LOOK FAIRLY LIGHT WITH THE SYSTEM FRIDAY NIGHT
THROUGH SATURDAY NIGHT. MENTIONED FREEZING RAIN FOR LATE FRIDAY
NIGHT INTO SATURDAY MORNING DUE TO WARM AIR ALOFT BUT LIGHT WINDS
AND POOR MIXING NEAR THE SURFACE. PRECIP AMOUNTS WILL BE FAIRLY
LIGHT THOUGH.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SYSTEM KICKS EAST OF THE AREA LATE SATURDAY NIGHT WITH A DRY AND
SEASONABLY COOL DAY FOR SUNDAY. HIGH PRESSURE BUILDS OVERHEAD FOR
LATE SUNDAY, BUT QUICKLY MOVES EAST. PRECIP CHANCES RETURN LATE
SUNDAY NIGHT AND CONTINUE THROUGH EARLY TUESDAY. HOWEVER, MODELS
ARE STILL HAVING TROUBLE WITH THIS SYSTEM. MODEL TREND, HOWEVER,
HAS BEEN FOR A WARMER SYSTEM WITH A POTENT SURFACE LOW TRACKING
FROM SOUTHWEST TO NORTHEAST FROM THE GREAT LAKES TO THE SAINT
LAWRENCE. THIS WOULD PUT US ON THE WARM SIDE OF THE STORM WITH
FREEZING RAIN CHANGING TO RAIN AND THEN BACK TO SNOW AT THE VERY
END.
DRY WEATHER FOR WEDNESDAY WITH COOL TEMPERATURES, BUT READINGS
RISING AS WE HEAD INTO THURSDAY AND FRIDAY.
&&
.AVIATION /19Z WEDNESDAY THROUGH SATURDAY/...
NEAR TERM: MAINLY VFR THROUGH THROUGH THURSDAY NIGHT W/A BRIEF
PERIOD OF MVFR THIS EVENING FOR SNOW SHOWERS. LLWS WILL BE A
CONCERN THROUGH 06Z AS THE COLD FRONT PASSES THROUGH.
SHORT TERM:
VFR FOR FRIDAY, BUT CONDITIONS WILL DETERIORATE TO MVFR AND
POSSIBLY IFR LATE FRIDAY NIGHT AS ONSHORE FLOW DEVELOPS. MVFR AND
IFR EXPECTED FOR SATURDAY WITH LIGHT PRECIPITATION AND LOW
CEILINGS.
&&
.MARINE...
NEAR TERM: KEPT THE SCA UP THROUGH 12Z THURSDAY. WINDS HAVE
DROPPED BELOW 20S KTS W/WAVE HEIGHTS 6-7 FT(COMBINED SEA/SWELL
STATE). EXPECTING WINDS TO COME BACK UP TONIGHT AS THE FRONT AND
CAA HIT THE WATERS. STAYED W/GUSTS TO 30 KTS THIS EVENING AND THEN
BROUGHT WINDS DOWN AFT 12Z AS HIGH PRES PUSHES QUICKLY E. THE SEAS
WILL BE SLOWER TO RESPOND INITIALLY HOLDING UP TO 3-5 FT AND THEN
FALLING BACK BY EARLY THURSDAY AFTERNOON INTO THURSDAY NIGHT.
SHORT TERM:
WINDS AND SEAS EXPECTED TO INCREASE TO SMALL CRAFT LEVELS FRIDAY
BUT DIMINISH TO JUST UNDER SMALL CRAFT LEVELS ON SATURDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR ANZ050>052.
&&
$$
NEAR TERM...HEWITT
SHORT TERM...FOISY
LONG TERM...JORDAN
AVIATION...HEWITT/FOISY
MARINE...HEWITT/FOISY
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1020 AM CST WED DEC 5 2012
.DISCUSSION...
WIND...TEMPERATURES AND LIGHT PRECIPITATION CONTINUE TO BE A
CHALLENGE TODAY. MODELS ARE IN GOOD AGREEMENT...BUT WILL LEAN ON
HIGH RESOLUTION RAP FOR FORECAST DETAILS.
15 UTC RAP SHOWS A NARROW CORRIDOR OF 40 TO 50 KTS AT 925 HPA
SLIDE ACROSS THE FORECAST AREA TODAY. MODEL SOUNDINGS SUGGEST A
VERY SHALLOW MIXED LAYER...UP TO 950 HPA AT 18 UTC AND BRIEFLY
REACHING 925 HPA BY 21 UTC. THE STRONGEST WINDS WILL BE ACROSS THE
NORTHERN VALLEY WITH NEARLY 40 KTS AT THE TOP OF THE MIXED LAYER
BY MID-AFTERNOON. WIND ADVISORY CRITERIA MAY BE REACHED BRIEFLY
ACROSS PORTIONS OF PEMBINA/KITTSON/WALSH/MARSHALL COUNTIES...BUT
CONFIDENCE NOT HIGH ENOUGH TO ISSUE AT THIS TIME. WILL MONITOR
OBSERVATIONS CLOSELY AND ISSUE HEADLINES THIS AFTERNOON IF
NECESSARY. EITHER WAY...IT WILL BE BREEZY TO LOCALLY WINDY
TODAY...ESPECIALLY ALONG THE VALLEY FLOOR.
TEMPERATURES ALREADY IN THE UPPER TEENS TO MID 20S AND WITH STRONG
LOW-LEVEL WARM AIR ADVECTION AND SOME FILTERED SUN THROUGH MID-
HIGH LEVEL CLOUD COVER...AFTERNOON HIGHS WILL APPROACH 30 DEGREES
ACROSS THE CANADIAN BORDER AND THE MID TO UPPER 30S ACROSS THE
SOUTHERN VALLEY.
TRIMMED 20 POPS LATE AFTERNOON AS IT APPEARS ANY LIGHT FREEZING
RAIN SHOULD HOLD OFF UNTIL AFTER 0O UTC. WILL FURTHER ADDRESS
FREEZING PRECIPITATION WITH AFTERNOON FORECAST PACKAGE.
&&
.AVIATION...
EXPECTING MAINLY VFR MID/HIGH CLOUD COVER TODAY WITH SOME LOWER VFR
CIGS MOVING INTO NW FA LATE AFTERNOON. WINDS WILL INCREASE OUT OF
THE SE AND WILL BE BREEZY TO WINDY THIS AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 340 AM CST WED DEC 5 2012/
DISCUSSION...
FORECAST CHALLENGE CONCERNS LOW PCPN CHANCES LATE AFTERNOON INTO
TONIGHT...WIND AND TEMPERATURES.
MODELS OVERALL IN FAIR AGREEMENT AND WILL USE BLEND.
NEXT SHORTWAVE CROSSING NORTHERN ROCKIES WILL SPREAD ACROSS FA LATE
THIS AFTERNOON INTO TONIGHT. AS ASSOCIATED COLD FRONT APPROACHES
LATE THIS AFTERNOON MODELS PAINTING SOME LIGHT QPF ENTERING FA.
BASED ON GOOD MODEL AGREEMENT WILL DELAY ANY CHANCES UNTIL CLOSER TO
EVENING. MOISTURE THROUGH COLUMN NOT VERY IMPRESSIVE SO WILL NOT BE
INCREASING POPS. UNTIL THEN MIXING/WARM ADVECTION INCREASES DURING
THE DAY. WILL BE BREEZY TO WINDY HOWEVER NOT ANTICIPATING ADVISORY
CRITERIA WINDS AS MIXED LAYER VERY SHALLOW WITH STEEP INVERSION.
MOST WARM ADVECTION TODAY WILL BE ALOFT HOWEVER WITH MIXING/FILTERED
SOLAR AND LACK OF SNOW COVER TEMPERATURES ACROSS NORTH SHOULD RANGE
AROUND FREEZING AND CLOSE TO 40 ACROSS THE SOUTH. SURFACE
TEMPERATURES WILL DETERMINE WHETHER ANY PCPN WILL BE -SHRA OR PATCHY
FREEZING RAIN LATER TODAY.
COLD FRONT SCOOTS ACROSS FA TONIGHT. MODELS CONTINUE TO SHOW QUICK
SHOT OF PCPN ALONG AND AHEAD OF BOUNDARY. MOISTURE CONTINUES TO LOOK
VERY LIMITED BASED ON SOUNDING PROFILES. BEST CHANCES FOR ANY
FREEZING PCPN LOOKS TO BE ACROSS THE NORTH CLOSER TO UPPER SUPPORT.
ANY PCPN WHICH DOES OCCUR LOOKS TO BE LIGHT AND QUICK MOVING SO AT
THIS POINT NOT ANTICIPATING ANY HEADLINES BUT WILL NEED TO MONITOR.
BASED ON TIMING DID BACK UP SLIGHT CHANCE POPS FARTHER WEST BUT
CONFIDENCE LOW. CLOUDS AND MIXING SHOULD OFFSET COLD ADVECTION
KEEPING MINIMUMS RELATIVELY MILD.
HIGH BUILDS IN THURSDAY. COLUMN COOLER AND COULD SEE SOME CU
DEVELOPMENT WITH CONVECTIVE TEMPERATURES AROUND 30F. THIS SHOULD
KEEP TEMPERATURES A FEW DEGREES COOLER THAN TODAY. LACK OF SNOW
COVER ALWAYS A CHALLENGE THIS TIME OF SEASON FOR TEMPERATURES SO
WILL NOT GO AS COOL AS FAVORED GUIDANCE SUGGESTS.
SECONDARY COLD FRONT BEGINS TO PULL COLDER TEMPERATURES SOUTHWARD
THURSDAY NIGHT/FRIDAY WHICH SHOULD KEEP TEMPERATURES CLOSER TO
AVERAGE. WITH SURFACE HIGH PUSHING IN MODELS GENERALLY TRENDING
FARTHER SOUTH WITH NEXT PCPN CHANCES FRIDAY AND HAVE TRIMMED POPS
BACK CLOSER TO THE ND/SD/MN BORDER AREA.
LONG TERM...SATURDAY THROUGH TUESDAY.
GENERAL PATTERN CHANGE WITH LONG WAVE TROUGH OVER THE ROCKIES ON SAT
WILL SHIFT INTO THE PLAINS BY TUE. SPLIT FLOW EXPECTED THIS PERIOD.
UPPER AIR PATTERN AS WELL AS THE LOW LEVEL THERMAL FIELD WERE
FASTER WITH THE ECMWF THAN THE GFS IN BOTH STREAMS. WILL PREFER THE
SLOWER GFS.
WILL SLOW DOWN PRECIPITATION FOR MON. WILL LEAVE THE REST OF THE
PERIOD AS IS FOR PRECIPITATION.
WENT WARMER SAT...MON AND TUE BY A COUPLE DEGREES AND A LITTLE
COOLER FOR SUN.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
ROGERS/VOELKER
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
255 PM EST WED DEC 5 2012
.SYNOPSIS...
A COLD FRONT WILL REACH THE SOUTH CAROLINA COAST THIS EVENING. HIGH
PRESSURE WILL RETURN OVER THE AREA FOR THURSDAY AND FRIDAY. EXPECT
THIS HIGH TO BECOME CENTERED OFF THE EAST COAST WHICH WILL RESULT IN
A STRONG SOUTHERLY FLOW OF WARM AND MOIST AIR OVER THE WEEKEND.
ANOTHER COLD FRONT WILL APPROACH THE REGION EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH THURSDAY/...
AT 230 PM... FOR THE REMAINDER OF THE AFTERNOON... SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM OR TWO WILL ADVANCE ACROSS THE
PIEDMONT AS THE LEADING EDGE OF THE FRONTAL BOUNDARY SINKS SLOWLY
SOUTHWARD THROUGH THE SOUTH CAROLINA ZONES. RAP INDICATES SURFACE
DEWPOINTS CLOSE TO 60 DEGREES WILL POOL IN THE UPSTATE DUE TO
CONVERGENCE IN THE FRONTAL ZONE. THIS IS THE AREA WITH CAPES IN THE
150 TO 300 J/KG RANGE. THUS... ANY THUNDER THAT DOES OCCUR IS MOST
LIKELY ACROSS THE SOUTHERN PIEDMONT OF NORTH CAROLINA AND THE
UPSTATE OF SOUTH CAROLINA THROUGH EARLY EVENING. OTHERWISE... DRIER
AIR WILL SPREAD INTO THE NORTHERN ZONES AND PARTIAL CLEARING WILL
OCCUR THERE TONIGHT.
500 MB FLOW ACROSS THE CWA DURING THE NEAR TERM PART OF THE FORECAST
WILL BE PRIMARILY FROM THE WEST. THE TROUGH ALOFT MOVING ACROSS THE
GULF OF MEXICO TONIGHT AND THURSDAY WILL NOT BE A MAJOR PLAYER IN
OUR WEATHER. A STRONG SHORT WAVE TROUGH MOVING THROUGH NEW ENGLAND
AND EASTERN CANADA WILL BE THE MAIN FEATURE PUSHING THE COLD FRONT
SOUTH OF THE AREA THIS EVENING. SURFACE HIGH BEHIND THE FRONT WILL
BE OVER THE GREAT LAKES THIS EVENING MOVING TO A POSITION OVER THE
MID-ATLANTIC STATES AND NEW ENGLAND THURSDAY AFTERNOON. THE COLD AIR
DAMMING PATTERN THAT DEVELOPS WILL RESULT IN A NORTHEAST WIND AND
TEMPERATURES TOMORROW THAT ARE MUCH CLOSER TO NORMAL THAN THE
TEMPERATURES OF RECENT DAYS. BY THE END OF THE PERIOD... THE HIGH
CENTER IS ALREADY SHOWING SIGNS OF DRIFTING OFFSHORE... BUT THE
SOUTHWESTERN NOSE OF THE HIGH WILL CONTINUE TO EXTEND SOUTHWESTWARD
INT THE CWA DURING EARLY EVENING THURSDAY. THE FRONTAL ZONE TO OUR
SOUTH WILL NEVER QUITE CLEAR THE FAR WESTERN ZONES AND THE AIR MASS
CHANGE THERE WILL BE LESS NOTICEABLE THAN EAST OF THE MOUNTAINS.
QUITE A BIT OF FRONTAL ZONE MOISTURE WILL REMAIN OVER THE AREA...
BUT NORTHERN ZONES WILL HAVE A PERIOD OF NEARLY CLOUD FREE SKIES
BEFORE CLOUDS RETURN DURING THURSDAY AS ISENTROPIC LIFT DEVELOPS
OVER THE SOUTHWESTERN PERIPHERY OF THE OFFSHORE HIGH.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 145 PM WEDNESDAY...SFC RIDGING...NOSED SSWWD INTO THE CWFA...
WILL LINGER THRU THURSDAY NIGHT. FORCING FOR ANY PCPN WILL BE IN THE
FORM OF WEAK UPGLIDE/UPSLOPE...RESULTING IN SCATTERED LIGHT
RAIN/SHOWER/DRIZZLE POSSIBILITIES...MAINLY ACRS THE MTNS/FTHLS.
MOUNTAIN MIN TEMPS SHOULD EXPERIENCE A NEGATIVE VALLEY TO RIDGETOP
LAPSE RATE...AND AT THIS JUNCTURE...WE ARE EXPECTING EVEN THE
COLDEST NC MTN VALLEYS TO REMAIN JUST ABOVE FREEZING. LLVL WAA FLOW
REGIME IS PROGGED TO LINGER ATOP WEAKENING SFC RIDGE ON FRIDAY.
SHORT RANGE MODELS CONTINUE TO ADVERTISE SPOTTY RESPONSE AND WOULD
EXPECT THE PROSPECT FOR ANYTHING MORE THAN FILTERED OR DIM SUNSHINE
DEVELOPMENT TO BE LOW. NONETHELESS...TEMPERATURES SHOULD MODERATE
SOME FROM THURSDAY/S CHILLY READINGS...WITH A MOS BLEND SUPPORTING
ABOUT A 5 DEG F BUMP. A DEEPER/QUICKENING WSW FLOW WILL DEVELOP ATOP
THE SE CONUS ON SATURDAY ERODING THE LINGERING COOL WEDGE AND
CONTRIBUTING TO TEMPERATURES WARMING TO 10 DEG F ABOVE CLIMO. A
FRONTAL BNDRY IS PROGGED TO MAKE A PUSH TOWARD THE MTNS LATE IN THE
DAY BUT SHOULD STALL WELL NW OF THE AREA. PLUME OF WEAK INSTABILITY
AHEAD OF THIS FEATURE COMBINED WITH TERRAIN LIFT COULD BE ENOUGH TO
TRIGGER A FEW MTN SHOWERS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM WEDNESDAY...MODELS HAVE CONVERGED ON THE TIMING OF A
COLD FROPA ON MONDAY...AS A LOW PRES SYSTEM TRACKS FROM THE SOUTHERN
PLAINS TO THE GREAT LAKES OVER THE WEEKEND. BEFORE THE FRONT
ARRIVES...PERSISTENT DEEP SWLY FLOW WILL CONTINUE ACRS THE FA. MOS
SEEMS OVERDONE ON POPS THRU SUNDAY NIGHT...AS THE ONLY FORCING FOR
PRECIP WILL BE UPSLOPE IN THE SW NC MTNS. I AM UNDERCUTTING THE
GUIDANCE ON POPS SATURDAY NIGHT THRU SUNDAY NIGHT.
THE LATEST MODEL CONSENSUS HAS THE FRONT CROSSING THE CWFA FROM WEST
TO EAST DURING THE DAY ON MONDAY. A FAIRLY GOOD MOISTURE PLUME WILL
ACCOMPANY THE FRONT WITH STRONG UPPER LEVEL DIVERGENCE. SO POPS ARE
RAMPED UP TO LIKELY IN THE MTNS AND HIGH-END CHC EAST. THIS WOULD BE
A MORE FAVORABLE TIME OF DAY FOR INSTBY. WITH THAT SAID...THE MODELS
ARE STILL MEAGER ON SBCAPE...WITH THE GFS AND ECMWF HAVING 100-200
J/KG AHEAD OF THE FRONT. SHEAR DOES LOOK GOOD THO...WITH SWLY 0-6KM
BULK SHEAR 50-60 KTS IN THE PIEDMONT AND EVEN GREATER TO THE WEST.
THE GFS FCST SNDG SHOWS SOME DIRECTIONAL SHEAR AS WELL WITH 0-3KM
HELICITY IN THE 150-250 M2/S2 RANGE. SO EVEN A LITTLE INSTBY COULD
BE ENUF FOR A HIGH-SHEAR/LOW-CAPE SEVERE EVENT. USING THE GFS CAPE
AS A GUIDE...DID ADD SOME MENTION OF THUNDER FOR MONDAY.
MONDAY NIGHT INTO TUESDAY...AS THE LOW WRAPS UP OVR THE EASTERN
GREAT LAKES...NWLY LLVL FLOW WILL USHER IN COLD AIR ACRS THE AREA.
GUIDANCE SEEMS TO INDICATE THAT THE COLD AIR WILL CHASE THE
MOISTURE...SUCH THAT VERY LITTLE IF ANY SNOW WILL FOLLOW BEHIND THE
FROPA. I GRADUALLY RAMP POPS DOWN INTO TUESDAY...WITH SNOW LEVELS
POSSIBLY FALLING TO 3500 FT BEFORE DAYBREAK TUESDAY. NO SIGNIFICANT
ACCUMS ARE EXPECTED. TUESDAY WILL BE COOLER WITH TEMPS NEAR OR
SLIGHTLY BELOW NORMAL. DRY HIGH PRES BUILDS IN FOR WEDNESDAY.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
AT KCLT... LEADING EDGE OF SURFACE FRONTAL ZONE HAS MOVED SOUTH OF
KCLT SO THE WIND WILL SETTLE INTO A NORTHEAST DIRECTION THAT WILL
CONTINUE THROUGH THE REMAINDER OF THE AFTERNOON. SPEED WILL REMAIN
AROUND 10 KT OR LOWER. FRONTAL CLOUDS WILL CONTINUE TO AFFECT THE
TERMINAL WITH CEILING GENERALLY 5-7 KT FT. A BAND OF LIGHT RAIN AND
SHOWERS WILL AFFECT THE AIRFIELD THROUGH 22Z. AN AREA OF CAPES NEAR
300 J/KG WILL EXIST TO THE SOUTH OF THE AIRFIELD... BUT CAPES IN THE
IMMEDIATE VICINITY APPEAR TOO LOW TO SUPPORT THUNDER. THUS... CHANCE
OF A THUNDERSTORM IS NOT IN THE TAF AT THIS TIME. DURING THE
OVERNIGHT PERIOD... WEAK ISENTROPIC LIFT ASSOCIATED WITH COLD AIR
DAMMING WILL PRODUCE CLOUD BASES NEAR 5K FT. BY 09Z A SCATTERED TO
BROKEN LAYER AROUND 2K FT IS POSSIBLE BUT VISIBILITY SHOULD REMAIN
UNRESTRICTED.
ELSEWHERE... SURFACE FRONT WILL MOVE SOUTH OF KGSP/KGMU/KAND DURING
LATE AFTERNOON AND THIS EVENING. CEILINGS WILL GENERALLY BE IN THE
5-7K FT RANGE EXCEPT SCATTERED CEILING 3-4K FT IN SHOWERS AND
ISOLATED THUNDERSTORMS. DRIER AIR SPREADING INTO AREA FROM THE
NORTHEAST WILL RESULT IN CLOUDS SCATTERING OUT AT KHKY AFT 00Z...
BUT A 5K FT CEILING WILL RETURN THURSDAY MORNING. EVEN THOUGH FRONT
WILL BE SOUTH OF AREA... FRONTAL CLOUD BAND WILL REMAIN OVER THE
FORECAST AREA AS A RELATIVELY SHORT COLD AIR DAMMING PATTERN
DEVELOPS. WINDS WILL BECOME NORTHEAST AT ALL TERMINALS EXCEPT KAVL
WHERE NORTH TO NORTHWEST WIND WITH GUSTS TO 20 KT WILL CONTINUE INTO
TONIGHT.
OUTLOOK... WIDELY SCATTERED SHOWERS WITH CEILING AND VISIBILITY
RESTRICTIONS POSSIBLE OVER THE MOUNTAINS FRIDAY AND SATURDAY.
STRATUS AND FOG COULD OCCUR BOTH DAYS DUE TO WEAKENING COLD AIR
DAMMING. COLD FRONT CROSSING THE AREA MONDAY WILL PRODUCE SCATTERED
SHOWERS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...LGL
SHORT TERM...CSH
LONG TERM...ARK
AVIATION...LGL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
119 PM EST WED DEC 5 2012
.SYNOPSIS...
A COLD FRONT WILL DRIFT SOUTHEAST ACROSS THE AREA TODAY AND REACH
THE SOUTH CAROLINA COAST THIS EVENING. HIGH PRESSURE WILL RETURN
THURSDAY AND FRIDAY. EXPECT THIS HIGH TO BECOME CENTERED OFF THE
EAST COAST WHICH WILL RESULT IN A STRONG SOUTHERLY FLOW OF WARM AND
MOIST AIR OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 105 PM... EARLY AFTERNOON UPDATE CARRIES CHANCE POPS ACROSS NC
PIEDMONT AND SC UPSTATE AS SHOWERS ASSOCIATED WITH COLD FRONT
ADVANCE THROUGH THE AREA. CAPES ARE QUITE LOW... 100 TO 250 J/KG
ESPECIALLY ACROSS NORTHERN UPSTATE WHERE HIGHER DEWPOINTS ARE
COLLECTING IN FRONTAL CONVERGENCE ZONE. LIGHT RAIN OR SHOWERS SHOULD
BE THE PREDOMINANT FORM OF PRECIPITATION... BUT ISOLATED THUNDER
WILL BE MENTIONED TO ACCOUNT FOR MARGINALLY FAVORABLE AIR MASS.
AS OF 935 AM...RADAR SHOWING SHRA OVER THE NC PIEDMONT AND NE GA AND
NWRN UPSTATE AHEAD OF THE COLD FRONT SLOWLY MOVING ACROSS THE AREA.
EXPECT THE SHRA TO DIMINISH ACROSS THE NC PIEDMONT THIS MORNING
LEAVING ONLY SCT SHRA. THE SHRA OVER GA/SC WILL CONTINUE THRU THE
AFTERNOON AND MOVE EAST AND SOUTH ACROSS THAT AREA AS THE FRONT
SLOWLY SAGS SWD. WITH MOISTURE POOLING ALONG THE FRONT OVER THAT
AREA...DEW POINTS WILL REMAIN RELATIVELY HIGH FOR THIS TIME OF YEAR.
12Z RAOBS SHOW ELEVATED INSTABILITY OVER THE AREA WITH WEAK LAPSE
RATE INCREASE DUE TO COOLING MID LEVELS. HAVE RETAINED TSRA WORDING
ACROSS NE GA/UPSTATE IN LINE WITH THESE TRENDS. TEMPS WILL BE TRICKY
WITH THE FRONTAL MOVEMENT AND VERY WARM START TO THE DAY. UPDATED
HIGHS BASED ON CURRENT GUIDANCE WHICH DID MAKE SOME MINOR CHANGES.
AS OF 635 AM EST WEDNESDAY...LOCAL RADAR...SFC OBS AND IFLOWS
OBSERVATIONS SHOW THAT SHOWERS HAVE INCREASED OVER THE NC AND NE GA
MTNS THE PAST FEW HOURS. THIS IS IN LINE WITH THE FORECAST. SOME
LIGHTER SHOWERS ARE ALSO FALLING OVER THE FOOTHILLS AND
PIEDMONT...BUT THEY ARE LIGHTER. A MORE CONCENTRATED AREA OF RAIN
HAS DEVELOPED OVER NRN GA AND SHOULD MOVE INTO RABUN...HABERSHAM AND
OCONEE COUNTIES OVER THE NEXT COUPLE HOURS.
AS OF 435 AM EST WEDNESDAY...ADJUSTED MIN TEMPS UP A COUPLE DEGREES
BASED ON INCREASING CLOUD COVER. PATCHY LIGHT RAIN AND A FEW HEAVIER
SHOWERS ARE DEVELOPING OVER WRN NC AND ALONG THE TN LINE. THIS LINES
UP FAIRLY WELL WITH THE GRADUALLY INCREASING POP TREND IN THE GRIDS.
PREVIOUS DISCUSSION...
A STRONG TROUGH WILL MOVE ACROSS THE NEW ENGLAND STATES
TODAY...WHILE A CUT-OFF SRN STREAM LOW DRIFTS DOWN INTO THE NRN GULF
OF MEXICO. A SFC FRONT WILL STALL OVER THE MOUNTAINS THIS
MORNING...THOUGH HEIGHT RISES ACROSS THE MID-ATLANTIC STATES WILL
SEND THE THE FRONT SURGING SOUTHWARD A LITTLE LATER IN THE DAY. WEAK
H8 FRONTOGENESIS WILL ACCOMPANY THE BNDRY...THOUGH THE DEEP LAYER
FORCING LOOKS WEAK. LOW LEVEL CONVERGENCE WILL POOL MOISTURE AHEAD
OF THE FRONT AND MOST OF THE NUMERICAL MODELS DEVELOP ENOUGH
INSTABILITY OVER THE UPSTATE...SRN NC MTNS AND NE GA TO SUPPORT
SHOWERS AND EVEN A FEW TSTMS THIS AFTERNOON. THE NAM IS A LITTLE
FASTER THAN THE GFS...WHILE THE RUC IS A HAIR SLOWER THAN EITHER
MODEL. I HAVE EXTENDED THUNDER CHANCES UP ACROSS THE SRN NC MTNS AS
I DON/T SEE THE BNDRY MAKING IT THROUGH THESE AREAS UNTIL LATE AFTN.
IN FACT...THE FRONT WILL MAKE IT THROUGH CHARLOTTE AND THE NE
UPSTATE BEFORE THE CLEARS THE ESCARPMENT. CONVECTION IS EXPECTED TO
THEN SETTLE SOUTHWARD ACROSS THE UPSTATE AND NE GA. ATTM I DON/T
EXPECT ANYTHING SEVERE OWING TO THE MOIST MID-LEVELS AND WEAK LAPSE
RATES.
HIGH PRESSURE WILL CONTINUE TO RIDGE DOWN THE EAST SLOPES OF THE
APPALACHIANS TONIGHT. THE 1031 MB SFC HIGH CENTERS OVER PENNSYLVANIA
QUALIFIES AS A CLASSICAL COLD AIR DAMMING...AND IT WILL BRING A GOOD
INFLUX AND COOL AND DRY LOW LEVEL AIR INTO THE REGION. SKIES SHOULD
CLEAR OVERNIGHT ACROSS MUCH OF NORTH CAROLINA...AT LEAST NORTH OF A
LINE FROM CHARLOTTE TO ASHEVILLE...WHILE SKIES REMAIN CLOUDY OVER
THE UPSTATE AND NE GA ATOP THE DAMMING AIRMASS. THE MOISTURE LOOKS
SHALLOW AND PCPN CHANCES WILL BE LOW AND CONFINED TO THE SRN MOST
ZONES.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 245 AM WEDNESDAY...SHORT RANGE MODELS BEGIN THE SHORT RANGE
PERIOD...12Z THURS...IN GOOD AGREEMENT WITH THE POSITION OF THE BACK
DOOR COLD FRONT ACROSS THE UPPER SAVANNAH RIVER VALLEY AND SFC HIGH
PRESSURE CENTERED OVER THE MID ATLANTIC AND NEW ENGLAND STATES. AT
H5...A TROF IS EXPECTED TO PIVOT OVER THE NRN GULF...SUPPORTING THE
FORMATION OF A WEAK LOW NEAR THE MISSISSIPPI DELTA DURING THE
DAYLIGHT HOURS. AT 295K...WEAK ISENTROPIC LIFT IS EXPECTED TO
CONTINUE OVER NE GA AND THE WESTERN CAROLINAS THROUGH THURSDAY.
FORECAST SOUNDINGS INDICATE THAT THE CLOUD LAYER MAY RANGE BETWEEN
5-10 KFT...WITH LLVL NE FLOW. LLVL LIFT AND THICK MOISTURE MAY YIELD
PATCHES OF -RA TO SPRINKLES...BUT MEASURABLE QPF SEEMS UNLIKELY.
HOWEVER...GIVEN THE THICK CLOUD COVER FROM SUNRISE TO SUNSET AND
PERSISTENT NE FLOW...HIGH TEMPERATURES SHOULD VERIFY FAIRLY UNIFORM
ACROSS THE CWA ON THURSDAY. I WILL POPULATE TEMPS FROM THE NAM 2M
TEMPS...YIELDING HIGH TEMPERATURE FORECAST FROM THE MID 50S ALONG
AND EAST OF I-85 TO NEAR 50 ALONG AND NORTH OF I-40.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE CENTER OF HIGH PRESSURE SHOULD
SLIDE OVER THE WESTERN ATLANTIC AS LOW PRESSURE DEVELOPS OVER THE
CENTRAL PLAIN AND MID MISSISSIPPI RIVER VALLEY. FORECAST SOUNDINGS
INDICATE THAT CLOUD COVER WILL REMAIN PLENTIFUL ACROSS THE CWA
THROUGH THE PERIOD. LLVL LIFT AND SYNOPTIC SCALE FORCING WILL REMAIN
VERY WEAK...SUPPORTING MAINLY SCHC POPS ACROSS THE MTNS AND
FOOTHILLS. TEMPERATURES WILL GRADUALLY MODERATE THROUGH THE
PERIOD...REMAINING WELL ABOVE NORMAL AT NIGHT AND NEAR NORMAL FOR
FRIDAY HIGHS.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 240 AM WEDNESDAY...THE MEDIUM RANGE WILL BE A PERIOD OF TIME
UNDER THE INFLUENCE OF A SOUTHERLY FLOW PRIOR TO THE ARRIVAL OF A
COLD FRONT IN THE FIRST HALF OF THE WEEK. HIGH PRESSURE WILL BE
CENTERED NEAR BERMUDA WITH A SOUTHERLY FLOW WHICH WILL CONTINUE
THROUGH THE WEEKEND AND TO START THE WEEK AHEAD OF THE FRONT. ALL
MODELS AGREE ON THE GENERAL WEEKEND SCENARIO WITH THE WARMTH AND
MOISTURE ADVECTION AND SLIGHT TO LOW CHANCE POPS FROM NE GA TO
ACROSS THE WESTERN CAROLINAS.
THE GFS MODEL IS MOST PROGRESSIVE WITH THE FRONT MOVING EAST OF OUR
AREA MONDAY EVENING. SOME CAPE VALUES OF AROUND 20 ON GFS SATURDAY
AFTERNOON IN THE NC MTNS THEN RISE TO AROUND 160 OVER THE SMOKIES
SUNDAY AFTERNOON. IT ALL COMES TOGETHER ON THE GFS MONDAY AFTERNOON
WITH CAPES OF AROUND 160 FROM NE GA TO THE NC MTNS AND 850MB WIND 40
TO 50 KTS AND 700MB WIND 55 TO 65 KTS.
THE LATEST ECMWF WHICH JUST ARRIVED IS CLOSER TO THE GFS NOW IN
TIMING AND HAS THE FRONT EAST OF OUR AREA EARLY TUESDAY MORNING.
EARLIER RUN HAD THE FRONT ARRIVING EARLY TUESDAY AFTERNOON. WIND
SPEEDS ARE COMPARABLE TO THE GFS AND NOW SINCE THE ECMWF FRONT
ARRIVES EARLIER THE CAPES ARE HIGHER AS WELL. ECMWF HAS CAPES OF
400 TO 600 MONDAY AFTERNOON ALONG THE I-85 CORRIDOR. SINCE BOTH ARE
IN BETTER AGREEMENT...WILL INCREASE POPS LATE MONDAY AND THEN
DECREASE POPS TUESDAY AS THE FRONT SHOULD BE OUT OF THE AREA TO
EAST.
TEMPERATURES WILL BE 10 OR MORE DEGREES ABOVE NORMAL AHEAD OF THE
FRONT AND THEN STARTING A COOLING TREND BEHIND THE FRONT ON DAY 7
TUESDAY.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AT KCLT... LEADING EDGE OF SURFACE FRONTAL ZONE HAS MOVED SOUTH OF
KCLT SO THE WIND WILL GRADUALLY SHIFT FROM NORTHWEST TO NORTHEAST
THROUGH THE REMAINDER OF THE AFTERNOON. SPEED WILL REMAIN AROUND 10
KT OR LOWER. FRONTAL CLOUDS WILL CONTINUE TO AFFECT THE TERMINAL
WITH CEILING GENERALLY 5-7 KT FT. SHOWERS THAT WERE CONSOLIDATING
WEST OF KCLT... OVER THE FOOTHILLS... COULD AFFECT THE AIRFIELD BY
20Z OR SO. AN AMENDMENT WILL BE ISSUED IF THEY HOLD TOGETHER. DURING
THE OVERNIGHT PERIOD... WEAK ISENTROPIC LIFT ASSOCIATED WITH COLD
AIR DAMMING WILL PRODUCE CLOUD BASES NEAR 5K FT. BY 09Z A SCATTERED
TO BROKEN LAYER AROUND 2K FT IS POSSIBLE BUT VISIBILITY SHOULD
REMAIN UNRESTRICTED.
ELSEWHERE... SURFACE FRONT WILL MOVE SOUTH OF KGSP/KGMU/KAND DURING
MID TO LATE AFTERNOON. CEILINGS WILL GENERALLY BE IN THE 5-7K FT
RANGE EXCEPT SCATTERED CEILING 3-4K FT IN SHOWERS. DRIER AIR
SPREADING INTO AREA FROM THE NORTHEAST WILL RESULT IN CLOUDS
SCATTERING OUT AT KHKY AFT 00Z... BUT EVEN THEIR CEILING NEAR 5K FT
WILL RETURN THURSDAY MORNING. EVEN THOUGH FRONT WILL BE SOUTH OF
AREA... FRONTAL CLOUD BAND WILL REMAIN OVER AREA AS CA RELATIVELY
SHORT COLD AIR DAMMING PATTERN DEVELOPS. FOLLOWING FRONTAL
PASSAGE... WINDS WILL BECOME NORTHEAST AT ALL TERMINALS EXCEPT KAVL
WHERE NORTH TO NORTHWEST WIND GUSTY TO 20 KT AT TIMES WILL CONTINUE
INTO TONIGHT.
OUTLOOK...COLD AIR DAMMING MAY RESTRICT CIGS WEDNESDAY NIGHT INTO
FRIDAY. MORNING RESTRICTIONS IN FOG AND STRATUS ARE POSSIBLE EARLY
SATURDAY AND SUNDAY WITH FAIR CONDITIONS EXPECTED DURING THE
AFTERNOONS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...LGL
SHORT TERM...NED
LONG TERM...DEO
AVIATION...LGL
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1206 PM CST WED DEC 5 2012
.AVIATION...
CHALLENGES WILL BE WINDS AND FOG POTENTIAL OVERNIGHT INTO EARLY
THURSDAY AS WEAK WARM ADVECTION BEGINS ACROSS THE AREA.
AXIS OF RICHEST MOISTURE UNDERNEATH OLD FRONTAL INVERSION REMAINS
EAST OF I-35 AND APPEARS ITS RETREATING SLOWLY BACK EAST. WILL NOT
CARRY ANY MVFR THIS AFTERNOON AND KEEP LIGHT E/NE WINDS AND VFR
THROUGH MID-LATE EVENING.
SURFACE RIDGE SLIDES JUST SOUTHEAST OF ALL TERMINALS AFTER MIDNIGHT
WITH WEAK SE WINDS AT THE SURFACE AND WEAK WAA WITHIN THE BOUNDARY
LAYER BETWEEN 0.5-1.5 KM. THIS IS USUALLY A SET UP FOR AT LEAST
PATCHY AND POSSIBLY DENSE ADVECTION FOG...ESPECIALLY ON THE
PERIPHERY OF RICH BOUNDARY LAYER MOISTURE THAT OUR AIRPORTS WILL BE
WITHIN. THE RAP MODEL IS HANDLING BEST TODAY AND WILL FOLLOW THE
CLOSEST...AS MOS GUIDANCE AND EVEN MODEL BUFR SOUNDINGS ARE
STRUGGLING SOME ON WHAT TO FORECAST. EXPECT MVFR VSBYS LATER THIS
EVENING FALLING INTO IFR BEFORE SUNRISE.
CONFIDENCE IS LOW REGARDING TIMING AND HOW LOW CONDITIONS GET AND
WE MAY BE IMPROVING CONDITIONS TOO SOON CONSIDERING TIME OF YEAR.
SOUTH WINDS WILL INCREASE TO NEAR 10 KT LATE MORNING WITH WARMING
TEMPS AND VFR CONDITIONS RETURNING. TIMING AND RESTRICTION TRENDS
WILL CONTINUE TO BE EVALUATED THROUGH THIS EVENING.
05/
&&
.PREV DISCUSSION... /ISSUED 349 AM CST WED DEC 5 2012/
TODAY WILL BE A COOLER DAY BEHIND YESTERDAY/S COLD FRONT.
TEMPERATURES WILL CLIMB INTO THE 60S AND LOWER 70S THIS AFTERNOON.
SOME OF THE COOLEST AFTERNOON TEMPERATURES WILL LIKELY BE FOUND
OVER THE SOUTHEASTERN COUNTIES WHERE CLOUD COVER MAY PERSIST FOR
MUCH OF THE DAY. TONIGHT...THE RETURN OF SOUTHERLY WINDS IN THE
LOWER LEVELS OF THE ATMOSPHERE WILL BRING LOW-LEVEL MOISTURE
SURGING NORTH OVER THE REGION. HOWEVER...WITH THE SURFACE WIND
SPEEDS REMAINING BELOW 5 KTS...FOG COULD LIKELY DEVELOP OVER A
GOOD PORTION OF THE AREA. FOR NOW...HAVE HIGHLIGHTED ROUGHLY THE
SOUTHEASTERN HALF OF THE CWA WITH A MENTION OF FOG IN THE
ZONES...AND THE BEST CHANCES FOR WIDESPREAD FOG WILL BE SOUTH OF A
LINE FROM GOLDTHWAITE TO CANTON. IT IS POSSIBLE AREAS OF DENSE FOG
COULD DEVELOP AND WILL CONTINUE TO ASSESS THIS POTENTIAL TODAY. A
QUICK WARM-UP IS EXPECTED TOMORROW AS THE UPPER LEVEL PATTERN
RETURNS TO NEAR ZONAL FLOW AND SOUTHWEST WINDS AT H850 BRING
WARMER TEMPERATURES OVER THE REGION. TEMPERATURES TOMORROW WILL BE
IN THE 70S REGION-WIDE.
A FRONT THAT WILL DEVELOP TONIGHT OVER THE NORTHERN ROCKIES WILL
PUSH INTO THE NORTHWEST QUADRANT OF NORTH TEXAS ON FRIDAY. THERE
IS CONSIDERABLE UNCERTAINTY AMONGST THE MODELS ON HOW EACH HANDLES
THE FRONT BUT THE OVERALL IMPACTS ARE RELATIVELY MINIMAL. THE GFS
AND NAM PUSH THIS WEAK FRONT THROUGH MOST OF THE CWA WHILE THE
ECMWF AND GEM HANG THE FRONT OVER THE NORTHERN HALF OF THE CWA.
GIVEN THE FORECASTED MODIFIED AIR BEHIND THIS FRONT AND THE UPPER
LEVEL ZONAL FLOW PATTERN...WILL SIDE WITH THE ECMWF/GEM FOR NOW
AND STALL THE FRONT GENERALLY NORTH OF I-20 FRIDAY NIGHT AND
SATURDAY. THERE IS A SLIGHT CHANCE FOR RAIN EAST OF HIGHWAY 75 AND
INTERSTATE 45 FRIDAY AFTERNOON AND NIGHT AS THE FRONT MOVES IN
AND A WEAK SHORTWAVE MOVES OVER THE REGION. PWATS WILL BE HIGHEST
OVER THE EASTERN COUNTIES BUT APPRECIABLE RAINFALL IS NOT
EXPECTED. WILL ONLY MENTION SHOWERS FOR NOW BUT AN ISOLATED
THUNDERSTORM IS POSSIBLE.
THE FORECAST FOR FRIDAY THROUGH SATURDAY NIGHT IS A LITTLE COMPLICATED
BY THE MODEL DISCREPANCIES WITH THE FRONT. ASIDE FROM THE
DIFFERENCE IN FRONTAL POSITION...THEY ALSO DIFFER IN CLOUD COVER
AND TEMPERATURES. WILL KEEP AREAS AHEAD OF THE FRONT PARTLY TO
MOSTLY CLOUDY WITH HIGHS IN THE MID TO UPPER 70S AND LOWS IN THE
50S AND 60S. BEHIND THE FRONT...TEMPERATURES WILL BE SLIGHTLY
LOWER WITH HIGHS IN THE LOWER 70S AND LOWS IN THE 40S TO AROUND 50
DEGREES.
THE BIG STORY IN THE FORECAST CONTINUES TO BE THE CANADIAN FRONT
THAT WILL COME SCREAMING THROUGH THE REGION EARLY NEXT WEEK. THE
TIMING OF THE FRONT TONIGHT IS FASTER WITH AN ARRIVAL NOW ON
SUNDAY. THE ECMWF IS SLIGHTLY SLOWER WITH THE FRONT THAN THE GFS
AND GEM AND WILL SIDE WITH THE GFS/GEM FOR NOW AS THESE FRONTS
TYPICALLY DO ARRIVE FASTER. FORECASTED HIGH TEMPERATURES ON SUNDAY
WILL BE REACHED EARLY IN THE DAY WITH THE FRONT ARRIVING DURING
THE MORNING HOURS. THE FORECAST SOUNDINGS DO NOT LOOK FAVORABLE
FOR ANY HOPE OF DECENT RAIN WHEN THE FRONT COMES THROUGH. THE
SOUNDINGS ARE PRETTY DRY WITH PWATS BELOW AN INCH...EXCEPT FOR IN
THE SOUTHEASTERN COUNTIES WHERE PWATS ARE 1-1.25 INCHES. HAVE
POPS SUNDAY AFTERNOON OVER ROUGHLY THE EASTERN 2/3RDS OF THE
CWA...THEN OVER THE FAR SOUTHERN COUNTIES ON SUNDAY NIGHT AS THE
FRONT CONTINUES TO PUSH SOUTH. AFTER THAT...A RAPID DRYING TREND
IS EXPECTED AS THE FRONT PUSHES INTO THE GULF OF MEXICO AND
FORECAST SOUNDINGS QUICKLY DRY OUT THE ATMOSPHERIC COLUMN. THE
ECMWF IS FAIRLY AGGRESSIVE WITH POST- FRONTAL PRECIPITATION
OCCURRING SUNDAY NIGHT BUT WILL KEEP THE FORECAST DRY BEHIND THE
FRONT DUE TO THE QUICK DRYING TREND ADVERTISED BY THE OTHER
MODELS. IF THERE WAS TO BE SOME POST- FRONTAL PRECIP...THE ECMWF
SUGGESTS IT WOULD BE A COLD RAIN IN OUR AREA. HOPEFULLY WE WILL
REACH SOME BETTER MODEL AGREEMENT WITH THE TIMING AND PRECIP BY
THE WEEKEND BUT WITH THE LATEST MODEL RUNS...THE CHANCE FOR
BENEFICIAL RAIN LOOKS PRETTY BLEAK.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 68 49 75 55 76 / 0 0 0 5 10
WACO, TX 70 45 76 54 77 / 0 0 0 5 10
PARIS, TX 66 43 71 52 73 / 0 0 0 5 20
DENTON, TX 68 45 74 54 74 / 0 0 0 5 10
MCKINNEY, TX 67 44 73 54 73 / 0 0 0 5 10
DALLAS, TX 68 50 75 56 77 / 0 0 0 5 10
TERRELL, TX 66 46 73 55 74 / 0 0 0 5 10
CORSICANA, TX 65 49 74 56 76 / 0 0 0 5 10
TEMPLE, TX 71 45 76 54 78 / 0 0 0 5 10
MINERAL WELLS, TX 68 42 78 50 73 / 0 0 0 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/82
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
356 PM CST WED DEC 5 2012
.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
355 PM CST WED DEC 5 2012
AT 3 PM...WATER VAPOR IMAGERY SHOWS A SHORT WAVE MOVING EAST
ACROSS EASTERN MONTANA. THE HIGH CLOUDS ASSOCIATED WITH THIS
SYSTEM HAS ALREADY ADVANCED EASTWARD INTO THE FORECAST AREA.
BUFKIT SOUNDINGS SHOW PLENTY OF DRY AIR BELOW 20K FEET. THE
MODELS ARE FAIRLY GOOD AGREEMENT THAT MODERATE TO STRONG 280-305K
ISENTROPIC LIFT WILL DEVELOP ACROSS THE AREA LATE THIS EVENING AND
THEN CONTINUE INTO MONDAY MORNING. IN ADDITION...THERE WILL
MODERATE TO STRONG 700-600 FRONTOGENESIS AROUND MIDNIGHT AND 900
TO 800 MB FRONTOGENSIS TOWARD MORNING. MUCH OF THIS LIFT GOES TO
SATURATION. AS A RESULT...NOT EXPECTING TOO MUCH PRECIPITATION
UNTIL AFTER 3 AM THURSDAY MORNING. THIS WILL BE MAINLY CONFINED
NORTH OF THE INTERSTATE 90 CORRIDOR. SOUNDINGS SUGGEST THAT THERE
WILL BE AN ELEVATED WARM LAYER. NORTH OF INTERSTATE 94...THE
HYDROMETERS WILL PARTIALLY MELT LEADING TO A MIXTURE OF
SLEET...SNOW...AND FREEZING RAIN. AS SURFACE TEMPERATURES WARM ON
THURSDAY MORNING...EXPECT THIS PRECIPITATION TO CHANGE OVER TO
RAIN. FOR THE REMAINDER OF THE AREA...THE WARM LAYER AND THE
SURFACE TEMPERATURES WILL BE WARM ENOUGH FOR THE PRECIPITATION TO
BE ALL RAIN.
ON THURSDAY AFTERNOON...A SURFACE COLD FRONT WILL BE LOCATED
ACROSS SOUTHWEST AND CENTRAL WISCONSIN AND NORTHEAST IOWA. HOWEVER
BY THIS TIME MUCH OF THE FORCING ALOFT WILL HAVE ALREADY MOVED
EAST OF THE AREA. AS A RESULT...LOWERED THE PRECIPITATION CHANCES
DOWN TO SLIGHT CHANCES.
ON THURSDAY NIGHT...THE GFS...GEM...AND ECMWF MOVE THE FRONT WELL
SOUTHEAST OF THE AREA. MEANWHILE THE NAM/WRF HOLDS THE FRONT JUST
SOUTHEAST OF THE FORECAST AREA. DUE TO THE NAM/WRF...HELD ONTO THE
20 AND 30 PERCENT PRECIPITATION PROBABILITIES FOR SNOW FOR
SOUTHWEST WISCONSIN AND NORTHEAST IOWA.
FROM FRIDAY INTO FRIDAY NIGHT...THE NAM/WRF HAS A STRONG
BAROCLINIC ZONE AND FROTOGENESIS ACROSS NORTHERN IOWA...SOUTHERN
WISCONSIN...AND NORTHERN ILLINOIS. DUE TO THIS...THEY SHOW STRONG
SURFACE CYCLOGENESIS DEVELOPING ALONG THIS BOUNDARY. AS A
RESULT...IT GENERATES A SWATH OF 2 TO 4 INCH SNOW ACROSS THE AREA
ON FRIDAY AND FRIDAY EVENING. MEANWHILE THE GFS...GEM...AND ECMWF
HAVE A MUCH WEAKER WAVE. IN ADDITION...THEY ARE ABOUT 6 HOURS
SLOWER WITH THIS WAVE. AS A RESULT...THE SNOW DOES NOT MOVE INTO
THE AREA UNTIL FRIDAY AFTERNOON AND THEN LINGERS INTO FRIDAY
NIGHT. LOOKING AT THE OPERATIONAL MODELS AND THE GFS
ENSEMBLE...BELIEVE THAT THE NAM/WRF IS AN OUTLIER...SO TRENDED
TOWARD THE OTHER SOLUTIONS. WITH THIS IN MIND...EXPECT SNOW
AMOUNTS UP TO AN INCH FROM THIS SYSTEM.
.LONG TERM...SATURDAY THROUGH WEDNESDAY
355 PM CST WED DEC 5 2012
ON SATURDAY...THE 05.12Z MODELS ARE IN GOOD AGREEMENT THAT WE WILL
SEE QUITE A BIT OF SUBSIDENCE IN THE WAKE OF THE SHORT WAVE. AS A
RESULT...TOOK OUT THE MENTION OF SNOW FOR THIS DAY.
FROM LATE SATURDAY NIGHT INTO MONDAY...THE MODELS CONTINUE TO
STRUGGLE WITH THIS TIME PERIOD. MUCH OF THIS HAS TO DEAL WHETHER
THERE WILL BE ANY PHASING OF THE NORTHERN AND SOUTHERN STREAM
SYSTEMS. BOTH THE GEM AND EMCMWF SUGGEST THAT THESE WAVES WILL NOT
PHASE...AND THE AREA WILL SEE SOME SNOW AS AN INVERTED TROUGH
MOVES NORTHEAST ACROSS THE AREA. MEANWHILE THE OPERATIONAL GFS
CONTINUES TO SHOW THAT THESE TWO SYSTEMS WILL PHASE. THIS RESULT
IN A MUCH STRONGER AND FURTHER NORTHWEST TRACK. IF THIS SCENARIO
DOES OCCUR...THERE COULD BE A BAND OF HEAVY SNOW ACROSS THE AREA.
HOWEVER THE GFS ENSEMBLE FAMILY ALSO SHOW A WIDE VARIETY OF
SOLUTIONS. ONLY 3 OF 12 WOULD SUPPORT THE OPERATIONAL GFS.
MEANWHILE THE REMAINDER EITHER SHOW THAT THE THE SOUTHERN STREAM
SYSTEM WILL BE WELL TO OUR SOUTHEAST...AND WE EITHER GET A LIGHT
DUSTING FROM THE NORTHERN STREAM OR SNOW AT ALL. AS A
RESULT...THERE IS MUCH LOWER CONFIDENCE IN THIS TIME PERIOD THAN
ONE MIGHT EXPECT BY JUST LOOKING AT THE OPERATIONAL MODELS.
&&
.AVIATION...THROUGH 18Z THURSDAY
1139 AM CST WED DEC 5 2012
MAIN AVIATION CONCERN IS WIND SHEAR THIS EVENING AND INCREASING
SOUTHERLY WINDS THIS AFTERNOON/EVENING AT BOTH LSE AND RST TAF
SITES. COLD FRONT OVER THE WESTERN DAKOTAS WILL PUSH EAST INTO
WESTERN WISCONSIN AND EASTERN IOWA THROUGH TAF FORECAST PERIOD. OUT
AHEAD OF THE COLD FRONT...A TIGHT SURFACE PRESSURE GRADIENT WILL
INCREASE SOUTHERLY WINDS THIS AFTERNOON AND EVENING WITH SUSTAINED
WINDS OF 13 TO 19 KNOTS AND GUSTS OF 20 TO 25 KNOTS EXPECTED. LATEST
05.12Z NAM AND 05.15Z RAP BUFKIT SOUNDINGS SHOW WIND SPEEDS AT
AROUND 2000 FEET ABOVE GROUND LEVEL TO BE NEAR 50 TO 55 KNOTS BY 04Z
TO 05Z THURSDAY AT BOTH TAF SITES. HAVE KEPT WIND SHEAR AT BOTH TAF
SITES. NEXT CONCERN IS PRECIPITATION CHANCES AND LOWERING OF CEILING
HEIGHTS AT TAF SITES. BOTH THE 05.12Z NAM AND 05.15Z RAP BUFKIT
SOUNDINGS INDICATE CEILING HEIGHTS LOWERING...HOWEVER THE CEILING
HEIGHTS WILL REMAIN IN THE VFR RANGE AT BOTH TAF SITES TONIGHT INTO
THURSDAY MORNING. BOTH THE 05.12Z GFS/NAM BUFKIT SOUNDINGS SHOW
ENOUGH LIFT...SATURATION OF ATMOSPHERE COLUMN AND ABOVE FREEZING
TEMPERATURES TO PRODUCE SOME RAIN SHOWERS ACROSS THE AREA AFTER
13Z THURSDAY. HAVE INTRODUCE RAIN SHOWERS AT TAF SITES AFTER 13Z
AND 15Z THURSDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
355 PM CST WED DEC 5 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...DTJ
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1211 PM CST WED DEC 5 2012
.UPDATE...
LAKE CLOUDS HAVE COME IN A BIT FARTHER AND MORE DENSE THAN
EXPECTED. WITH WIND SHIFTING TO ALLOW A LESS FAVORABLE FETCH AND
THE DELTA T DECREASING THINKING LOW CLOUDS WILL DIMINISH LATE THIS
AFTERNOON OR EARLY THIS EVENING. OTHERWISE...NO MAJOR CHANGES TO
THE FORECAST.
&&
.AVIATION/18Z TAFS/...
LAKE CLOUDS HAVE MOVED WELL ON SHORE...PARTICULARLY IN OZAUKEE AND
MILWAUKEE COUNTIES. HAVE KEPT A BROKEN DECK AT 2KFT FOR MKE AND
ENW THROUGH 21Z...THEN SCATTERED. HOPING FOR THE LESS FAVORABLE
WIND DIRECTION AND DELTA T TO HELP DIMINISH CLOUDS. HOWEVER...THE
LOW BROKEN DECK MAY PERSIST INTO THE EARLY EVENING.
DID NOT MENTION LOW LEVEL WIND SHEAR IN THE TAFS FOR TONIGHT...AS
IT LOOKS MARGINAL. WILL HAVE TO KEEP AN EYE OUT FOR IT...MAINLY IN
THE NORTHWEST AREA...AT MSN. HIGHEST WIND SPEEDS AROUND 2KFT DON/T
COME UNTIL ABOUT 10Z. BY THAT POINT...THE WARM AIR ADVECTION MAY
ALLOW ENOUGH MIXING TO RAISE SURFACE WINDS.
&&
.MARINE...
A SMALL CRAFT ADVISORY IS IN EFFECT FROM 08Z THURSDAY TO 00Z
FRIDAY. SOUTH WINDS WILL INCREASE AHEAD OF A LOW PRESSURE
DEEPENING AS IT TRACKS EASTWARD ACROSS SOUTHERN CANADA. WINDS WILL
BUILD HIGH WAVES FROM MILWAUKEE NORTH. SOUTH OF NORTH POINT THE
SHORTER FETCH IS EXPECTED TO KEEP WAVES JUST BELOW CRITERIA. THERE
WILL LIKELY STILL BE A FEW GUSTS TO 25 KNOTS SOUTH OF NORTH POINT
THOUGH. WINDS TURN SW AROUND 18Z THURSDAY AND DIMINISH BELOW
CRITERIA THROUGH THE AFTERNOON...BUT 00Z FRIDAY END TIME WILL
ALLOW WAVES TO SUBSIDE.
&&
.PREV DISCUSSION... /ISSUED 329 AM CST WED DEC 5 2012/
SHORT TERM...
TODAY.....FORECAST CONFIDENCE HIGH.
A DRY DAY WITH MID-UPPER LEVEL RIDGING BUILDING OVER REGION... AS
SURFACE HIGH PRESSURE SLIDES ACROSS THE WESTERN GREAT LAKES.
WATCHING BAND OF LAKE-EFFECT CUMULUS AROUND 3K FT DROPPING SOUTH
THROUGH LOWER MICHIGAN AND ERN HALF OF LAKE MI ON IR SATELLITE
IMAGERY. COULD BE SOME TWO-LAKE MOISTURE FEEDING THESE CLOUDS THAT
ARE ON LEADING EDGE OF POOL OF COLDEST 850 MB TEMPS THAT SLIDES BY
TO THE NORTHEAST TODAY. NW WINDS VEER NE BELOW 3K FT BY 15Z...BUT
WITH RELATIVELY WARM 850 MB TEMPS STAYING AROUND 0C WITH SUBSIDENCE
INVERSION DELTA T/S REMAIN AROUND 7C TO 9C. STEEP LAPSE RATES BELOW
2K FT/930 MB/ BUT LIMITED MOISTURE. EXCEPTION ARE RAP SOUNDINGS
WHICH INDICATE A BROKEN DECK FORMING MID AFTERNOON INTO THE EVENING.
WILL KEEP SKY COVER NO MORE THAN 50 PERCENT FOR NOW AND KEEP AN EYE
ON TRENDS.
WARM AIR ADVECTION BEGINS THIS AFTERNOON...WITH A 925 MB TEMPERATURE
GRADIENT SOUTHWEST TO NORTHEAST YIELDING NO BETTER THAN MID 30 HIGHS
IN THE NORTHEAST WITH AROUND 40 IN THE SOUTHWEST.
TONIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH.
WAA BRINGS MID TO HIGH LEVEL CLOUDS ACROSS THE FORECAST AREA THIS
EVENING...WITH 1-2 UBAR/SEC ISENTROPIC ADIABATIC OMEGA BRUSHING THE
NORTHWEST HALF OF CWA BETWEEN 06Z AND 12Z THURSDAY. HOWEVER MODEL
SOUNDINGS SHOW A VERY DRY LAYER BELOW 6-7K FT THAT NEVER
SATURATES...SUPPORTED BY CONDENSATION PRESSURE DEFICITS THAT NEVER
LOWER BELOW 100 MB ON 280K AND 285K SURFACES. WILL LIMIT SLIGHT
CHANCE POPS TO FAR NW. INCREASING CLOUDS AND WARM AIR ADVECTION ON
STRENGTHENING SOUTH WINDS LEADS TO A NON-DIURNAL TREND TO
TEMPERATURES...WITH LOWS AROUND 03Z THEN A SLOW RISE THROUGH
DAYBREAK.
THURSDAY THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM
STRONG LOW PRESSURE WILL ONCE AGAIN TRAVERSE EWD ACROSS CANADA
DURING THIS PERIOD BRINGING SSWLY FLOW AND LOW TO MID LEVEL WARM
ADVECTION FOR THU. THE WARM ADVECTION WILL LEAD TO WIDESPREAD
CLOUDS AND SMALL CHANCES OF RAIN FOR THU. THE CLOUDS WILL KEEP THE
TEMPS IN THE 40S THIS TIME AROUND. THE TRAILING COLD FRONT WILL
THEN SLOWLY MOVE SWD THROUGH THE AREA THU NT. MORE IMPORTANTLY...850-700
MB FRONTOGENESIS WILL BECOME ORGANIZED VIA CONFLUENT FLOW IN THAT
LAYER AS THE POLAR JET STREAM DROPS MORE SWD INTO THE USA. MOST
MODELS PRODUCE A SW TO NE BAND OF LGT RAIN THU NT SO WENT WITH
LIKELY POPS FOR THE CENTRAL AND SOUTHERN PORTIONS OF THE CWA.
LONG TERM...
FRIDAY NIGHT THROUGH TUESDAY...FORECAST CONFIDENCE LOW TO MEDIUM
A SHORTWAVE TROUGH WILL PASS FROM THE NRN PLAINS THROUGH WI FOR
FRI NT INTO SATURDAY BRINGING SMALL CHANCES OF LGT SNOW WITH THE
EXCEPTION OF A MIXTURE SAT AFTERNOON. AT THE SURFACE...WEAK HIGH
PRESSURE WILL BUILD INTO THE REGION.
DURING THE WEEKEND AN UPPER TROUGH WILL DIG INTO THE PLAINS AND
THEN SWING NEWD TOWARD THE OHIO RIVER VALLEY AND ERN GREAT LAKES.
AT THE SFC A MORE ORGANIZED SFC LOW WILL DEVELOP TO ERN IL BY 00Z MON
AND THEN NEWD THROUGH MI AND INTO QUEBEC FOR LATE ON MON. TIMING
AND STRENGTH DIFFERENCES REMAIN AMONG THE MODELS BUT NONETHELESS
SHOWING BETTER AGREEMENT. THIS SCENARIO RESULTS IN BETTER CHANCES
OF JUST SNOW AWAY FROM FAR SE WI BUT WILL STILL MENTION RAIN AND
SNOW OVER MOST OF THE AREA DUE TO UNCERTAINTY. PCPN TYPE WILL BE MAINLY
LIGHT SNOW FOR SUN NT THROUGH TUE WHILE ON THE BASKSIDE OF THE LOW
AND ANOTHER WEAK SHORTWAVE TROUGH FOR TUE.
AVIATION/12Z TAFS/...
WILL KEEP VFR CONDITIONS THROUGH THE FORECAST. CONCERN WITH
POTENTIAL MVFR LAKE-CLOUDS AS NORTH-NORTHWEST WINDS TURN NORTHEAST
LATE THIS MORNING...THEN EAST MID-AFTERNOON. SUBSIDENCE INVERSION
HOLDS STEEPER LAPSE RATES TO 2K FT OR LESS WITH LITTLE DEPTH TO
SATURATED LAYER ON NAM AND GFS SOUNDINGS...THOUGH RAP SOUNDINGS
INDICATE POTENTIAL FOR A BROKEN DECK AROUND 2K FT THIS AFTERNOON.
WITH COLD POOL THAT IS GENERATING CLOUDS OVER LOWER MICHIGAN SLIDING
BY TO THE NORTHEAST...WILL KEEP CURRENT SCATTERED 2K FT FOR TODAY
AND MONITOR DEVELOPMENTS TOWARD ISSUANCE.
COULD BE A PERIOD OF LOW-LEVEL WIND SHEAR THIS EVENING WITH 925 MB
WINDS INCREASING TO 30-35 KNOTS...BEFORE WARM AIR ADVECTION ALLOWS
ENOUGH MIXING TO RAISE SURFACE WINDS. DIFFERENTIAL IS HOVERING NEAR
BUT JUST BELOW CRITERIA SO WILL LEAVE OUT FOR NOW BUT BRIEF NEXT
SHIFT TO WATCH LATER MODEL RUNS.
MARINE...
QUIET TODAY...WITH NORTHWEST WINDS VEERING NORTHEAST AND THEN EAST
DURING THE DAY. ISSUED A SMALL CRAFT ADVISORY FOR THE NORTHERN TWO
NEARSHORE ZONES FOR 08Z THURSDAY TO 00Z FRIDAY AS SOUTH WINDS
INCREASE AHEAD OF LOW PRESSURE DEEPENING AS IT TRACKS FROM NEAR LAKE
WINNIPEG TO HUDSON BAY. THE WINDS WILL BUILD HIGH WAVES FROM
MILWAUKEE NORTH. THOUGH THERE WILL BE A FEW GUSTS TO 25 KNOTS...
WAVES SHOULD REMAIN JUST BELOW CRITERIA SOUTH OF MILWAUKEE DUE TO
MORE LIMITED FETCH. WINDS TURN SW AROUND 18Z THURSDAY AND DIMINISH
BELOW CRITERIA THROUGH THE AFTERNOON...BUT 00Z FRIDAY END TIME WILL
ALLOW WAVES TO SUBSIDE.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 2 AM TO 6 PM CST THURSDAY FOR LMZ643-
644.
&&
$$
UPDATE...BROOKS
TODAY/TONIGHT AND AVIATION/MARINE...REM
THURSDAY THROUGH TUESDAY...GEHRING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1139 AM CST WED DEC 5 2012
.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
348 AM CST WED DEC 5 2012
MAIN FORECAST CONCERNS THIS PACKAGE....PRECIP CHANCES/TYPES FOR ALL
OR PARTS OF THE FCST AREA AND TEMPERATURES THRU THE PERIOD.
DATA ANALYSIS AT 06Z HAD CAN HIGH PRESSURE CENTERED OVER MN WHILE
LEE TROUGHING WAS DEVELOPING OVER ALBERTA INTO MT/WY. SOME LAKE
EFFECT CLOUDS/FLURRIES OVER NORTHEAST WI...OTHERWISE CLEAR SKIES OR
SOME CIRRUS OVER THE REGION EARLY THIS MORNING. LIGHT WINDS AND THE
CLEAR/MOSTLY CLEAR SKIES WITH THE HIGH ALLOWING TEMPS TO DROP
CLOSER TO EARLY DEC LOWS THIS MORNING...WITH TEENS TO MID 20S COMMON
ACROSS MUCH OF MN/IA/WI.
NO PROBLEMS NOTED WITH 05.00Z MODEL INITIALIZATIONS. IN FACT ALL
LOOK QUITE GOOD. EVEN WITH A GOOD COMMON START...MODELS ALREADY
DIFFER FOR TONIGHT/THU WITH THE LOWER LEVEL MOISTURE AND PRECIP
CHANCES FOR THE AREA. SOME DIFFERENCES CONTINUE INTO FRI NIGHT BUT
THEY DO NOT LOOK TO GROW PROGRESSIVELY BIGGER FROM THOSE OF
TONIGHT/THU. DPROG/DT OF 500MB HGTS AT 05.00Z SHOWED THE MODEL RUNS
OF 03.00Z AND 04.00Z VERIFIED WELL ACROSS NOAM/EASTERN PAC. MODEL
CONSENSUS HAS TRENDED TOWARD FASTER OF EARLIER RUNS WITH FEATURES
FROM THE NORTHEAST CONUS TO EASTERN PAC. MODELS CONTINUE GENERAL
TREND OF DEVELOPING TROUGHING OVER THE CENTRAL/WESTERN CONUS IN THE
THU NIGHT TO FRI NIGHT PERIOD BUT PLENTY OF DIFFERENCES REMAIN WITH
STRENGTH/TIMING OF SHORTWAVE FEATURES THRU THIS FLOW. TREND FAVORS A
STRONGER FEATURE TO MOVE TOWARD/ACROSS THE UPPER MIDWEST FRI/FRI
NIGHT AND MORE RIDGING IN THE EASTERN PAC BY 12Z SAT. SOMEWHAT
BETTER RUN-TO-RUN CONSISTENCY BY ECMWF. PER SFC OBS...MODELS ALL
LOOKED TO BE PERFORMING QUITE WELL WITH THE SFC MASS FIELDS AT 06Z.
WV IMAGERY SHOWED ALL LOOKED GOOD WITH THE NOAM/ EASTERN PAC
SHORTWAVE DETAILS. NO CLEAR MODEL FAVORITE AGAIN...PERHAPS A SLIGHT
LEAN TOWARD THE ECMWF...THUS FAVORED THE MODEL/ENSEMBLE CONSENSUS.
GIVEN THE DETAIL DIFFERENCES ALREADY TONIGHT AND IMPACTS ON SENSIBLE
WEATHER...SHORT-TERM FCST CONFIDENCE AVERAGE THIS CYCLE.
IN THE SHORT TERM...ANOTHER QUIET DAY TODAY AS THE SFC HIGH SLIPS
SOUTHEAST OF THE AREA BUT A DRY SFC-700MB AIRMASS REMAINS OVER THE
AREA. SFC-700MB RIDGE AXIS MOVES EAST OF THE AREA BY 18Z WITH
INCREASING LOW LEVEL WARM ADVECTION SPREADING OVER THE AREA DURING
THE AFTERNOON. 925MB TEMPS ALREADY WARM TO -2C TO +4C BY 00Z THU...
BUT THIS WARMING OFFSET BY AN INCREASE OF HIGH LEVEL MOISTURE/
CLOUDS STREAMING EAST AHEAD OF THE NEXT TROUGH MOVING ACROSS THE
NORTHERN ROCKIES. WITH THE SNOW-FREE GROUND AND SOME SUNSHINE THIS
MORNING...HIGHS TODAY WILL AGAIN BE ABOVE NORMAL.
STRONGEST OF THE 925-700MB WARM ADVECTION/THERMO-DYNAMIC FORCING
MOVES ACROSS THE AREA TONIGHT. MUCH OF THIS CONTINUES TO GO INTO
WARMING...WITH 925MB TEMPS IN THE +2C TO +6C RANGE BY 12Z THU. WITH
THE LOWER LEVEL AIR MASS SOURCE REGION FROM THE CENTRAL PLAINS...
SFC-700MB LAYER STRUGGLES TO SATURATE...ESPECIALLY OVER THE SOUTHERN
2/3 OF THE FCST AREA. EVEN WITH THE DETAIL DIFFERENCES...BETTER
MODEL SIGNAL THAT SOME SFC-700MB SATURATION WILL OCCUR OVER THE FAR
NORTH END OF THE FCST AREA LATER TONIGHT/EARLY THU WHEN THE
STRONGEST OF THE LOWER LEVEL THERMO-DYNAMIC FORCING/LIFT PASS.
RAISED PRECIP CHANCES ACROSS THE NORTH END OF THE FCST AREA INTO THE
50-60 PERCENT RANGE LATE TONIGHT/THU MORNING WHILE MAINTAINING LOWER
PRECIP CHANCES OR A DRY FCST OVER THE CENTRAL/SOUTH PORTIONS OF THE
FCST AREA. THERMAL PROFILES ACROSS THE FAR NORTH END OF THE FCST
AREA CONTINUE TO INDICATE POTENTIAL FOR A WINTRY MIX...DEPENDING
ON HOW MUCH EVAPORATIVE COOLING OCCURS AS THE LOWER LEVEL SATURATE
FROM ABOVE. CONTINUED THE -RA/-FZRA/IP/-SN MENTION OVER THE
NORTH/EAST ENDS OF THE FCST AREA LATE TONIGHT/EARLY THU MORNING
UNTIL THE COLUMN AND/OR BOUNDARY LAYER BECOMES TOO WARM FOR THE
MIXED TYPES. ANY PRECIP AMOUNT AGAIN LOOK TO BE QUITE LIGHT.
SFC-500MB TROUGH AXIS SLIDES SOUTHEAST ACROSS THE AREA THU WITH
SOME 850-700MB FN CONVERGENCE AND GREATER 925-700MB MOISTURE/
SATURATION. CONTINUED RAIN CHANCES IN THE 25-50 PERCENT RANGE THU
AFTERNOON AND OVER THE SOUTHEAST END OF THE FCST AREA THU EVENING.
BRIEF BREAK FROM THE PRECIP CHANCES LATE THU NIGHT/FRI MORNING
BEFORE THE NEXT SHORTWAVE AND STRONGER ROUND OF 850-500MB FN
CONVERGENCE MOVE INTO THE AREA ALREADY FRI AFTERNOON. QUESTIONS/
DIFFERENCES AGAIN REMAIN WITH AMOUNT OF MOISTURE/SATURATION IN THE
SFC-700MB LAYER FRI AFTERNOON/EVENING BUT MODEL TREND IS TOWARD MORE
MOISTURE/SATURATION AND PRECIP PRODUCTION THESE PERIODS. MODEL
DIFFERENCES ALSO CONTINUE WITH THE LOWER LEVEL THERMAL PROFILES FRI
AFTERNOON/NIGHT...SOME COLD ENOUGH FOR ALL -SN SOME WITH A -RA/-SN
MIX BECOMING ALL SNOW. ADDED A 20-30 PERCENT -RA/-SN CHANCE TO MUCH
OF THE FCST AREA FOR FRI AFTERNOON AND CONTINUED THE 30 PERCENT -SN
CHANCE FRI NIGHT. IF THE COLDER...MORE MOIST SOLUTIONS ARE MORE
CORRECT...MUCH OF THE FCST AREA COULD SEE AND INCH OR TWO OF
SNOWFALL FRI AFTERNOON/ NIGHT.
FAVORING THE MODEL/ENSEMBLE CONSENSUS...GENERALLY FAVORED A BLEND OF
THE NUMERICAL TEMP GUIDANCE FOR HIGHS/LOWS TODAY THRU FRI NIGHT.
WITH THE PRECIP/SNOW CHANCES FRI AFTERNOON...DID TREND TOWARD COOLER
OF GUIDANCE HIGHS ON FRI.
.LONG TERM...SATURDAY THROUGH TUESDAY
348 AM CST WED DEC 5 2012
AS PREVIOUS FORECASTER STATED...A LOT OF UNCERTAINTY REMAINS IN THE
EXTENDED FORECAST. 05.00Z MEDIUM RANGE MODELS ARE SIMILAR ENOUGH
WITH THE BIG PICTURE OF A LONGWAVE TROUGH DEVELOPING INTO THE
CENTRAL CONUS BY SUN THEN MOVING IT INTO THE EASTERN CONUS BY TUE.
PLENTY OF TIMING/STRENGTH DETAIL DIFFERENCES WITH THE EVOLUTION OF
SHORTWAVES DROPPING INTO AND THRU THIS TROUGH BY SUN-TUE. THESE
DIFFERENCES BIG ENOUGH TO HAVE LARGE IMPACTS ON THE RESULTING
SENSIBLE WEATHER ON DAYS 5 THRU 7...THUS LONG-TERM FCST CONFIDENCE
REMAINS BELOW AVERAGE.
SOME CONSENSUS FOR WEAK HIGH PRESSURE AND SHORTWAVE RIDGING ALOFT
TO BUILD ACROSS THE UPPER MIDWEST IN THE WAKE OF THE FRI/FRI NIGHT
SYSTEM. GIVEN THE DETAIL DIFFERENCES FRI...A LINGERING SMALL -SN
CHANCE ON SAT PER THE MODEL/ENSEMBLE CONSENSUS LOOKS REASONABLE FOR
NOW. FOR SUN THRU TUE...ONE OR MORE OF THE MODELS SWING A
SIGNIFICANT MID LEVEL SHORTWAVE...SFC LOW/TROUGH AND DEEP LAYERED
FORCING/LIFT NORTHEAST NEAR OR ACROSS THE UPPER MIDWEST. MODEL
TRENDS SHOWING THE AIRMASS OVER THE AREA DURING THIS TIME WOULD BE
COLD ENOUGH FOR THE BULK OF ANY PRECIP IN SUN-TUE TIME-FRAME WOULD
FALL AS SNOW. WITH ALL THE DIFFERENCES...MADE NO CHANGES
TO THE MODEL/ENSEMBLE CONSENSUS DATA...BOTH PRECIP CHANCES AND
HIGHS/LOWS...IN THE DAY 5-7 FCST GRIDS.
&&
.AVIATION...THROUGH 18Z THURSDAY
1139 AM CST WED DEC 5 2012
MAIN AVIATION CONCERN IS WIND SHEAR THIS EVENING AND INCREASING
SOUTHERLY WINDS THIS AFTERNOON/EVENING AT BOTH LSE AND RST TAF
SITES. COLD FRONT OVER THE WESTERN DAKOTAS WILL PUSH EAST INTO
WESTERN WISCONSIN AND EASTERN IOWA THROUGH TAF FORECAST PERIOD. OUT
AHEAD OF THE COLD FRONT...A TIGHT SURFACE PRESSURE GRADIENT WILL
INCREASE SOUTHERLY WINDS THIS AFTERNOON AND EVENING WITH SUSTAINED
WINDS OF 13 TO 19 KNOTS AND GUSTS OF 20 TO 25 KNOTS EXPECTED. LATEST
05.12Z NAM AND 05.15Z RAP BUFKIT SOUNDINGS SHOW WIND SPEEDS AT
AROUND 2000 FEET ABOVE GROUND LEVEL TO BE NEAR 50 TO 55 KNOTS BY 04Z
TO 05Z THURSDAY AT BOTH TAF SITES. HAVE KEPT WIND SHEAR AT BOTH TAF
SITES. NEXT CONCERN IS PRECIPITATION CHANCES AND LOWERING OF CEILING
HEIGHTS AT TAF SITES. BOTH THE 05.12Z NAM AND 05.15Z RAP BUFKIT
SOUNDINGS INDICATE CEILING HEIGHTS LOWERING...HOWEVER THE CEILING
HEIGHTS WILL REMAIN IN THE VFR RANGE AT BOTH TAF SITES TONIGHT INTO
THURSDAY MORNING. BOTH THE 05.12Z GFS/NAM BUFKIT SOUNDINGS SHOW
ENOUGH LIFT...SATURATION OF ATMOSPHERE COLUMN AND ABOVE FREEZING
TEMPERATURES TO PRODUCE SOME RAIN SHOWERS ACROSS THE AREA AFTER
13Z THURSDAY. HAVE INTRODUCE RAIN SHOWERS AT TAF SITES AFTER 13Z
AND 15Z THURSDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
348 AM CST WED DEC 5 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...DTJ