Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 11/20/11
AREA FORECAST DISCUSSION
NWS DENVER CO
1010 AM MST FRI NOV 18 2011
.UPDATE...ONGOING FORECASTS STILL ON TRACK. CURRENTLY...WINDS ACROSS
MOUNTAINS AND ALONG FOOTHILLS BEGINNING TO DECREASE...IN LINE WITH
LATEST MODEL CROSS SECTIONS. WINDS TO INCREASE AGAIN AFTER
MIDNIGHT AS MODEL CROSS SECTIONS SHOW CROSS MOUNTAIN FLOW
INCREASING TO AROUND 75 KTS ALONG THE FOOTHILLS AFTER 09Z...IN
LINE WITH THE GREATEST DOWNWARD MOTION. SO CONCERN STILL EXISTS
FOR HIGH WIND POTENTIAL ALONG FOOTHILLS...SOUTH PARK AND PORTIONS
OF THE PALMER DIVIDE. THERE IS STILL A BIT OF VERTICAL SHEAR
ASSOCIATED WITH THE INCOMING JET WHICH COULD LIMIT THE HIGH WIND
POTENTIAL...SO WILL MAINTAIN THE HIGH WIND WATCH FOR NOW AND TAKE
A CLOSER LOOK FOR THE AFTERNOON PACKAGE. AS FOR SNOW POTENTIAL
TONIGHT...CROSS SECTIONS INDICATE AN INCREASE IN MOISTURE OVER
THE MOUNTAINS CLOSER TO MIDNIGHT...WHICH COULD DELAY THE TIMING OF
THE SNOW FOR ZONE 31. WILL LEAVE THE SLIGHT CHANCE THERE AFTER 00Z
FOR NOW.
&&
.AVIATION...CURRENT TAF TRENDS STILL LOOKING ON TRACK...WITH WIND
BEING THE MAIN ISSUE THROUGH TONIGHT. LATEST HRRR AND RUC STILL
BRING A WESTERLY PUSH OF WIND ACROSS THE AREA AIRPORTS BETWEEN 17Z
AND 21Z. WILL MAINTAIN THIS TREND IN THE 18Z TAFS. NO MAJOR
CHANGES NEEDED. LATEST NAM SUGGESTING FROPA AND NORTHERLY SURGE
AROUND 18Z AT DIA...THEN EASTERLY BY 21Z. THIS SEEMS REASONABLE...AND
WILL FOLLOW THIS TREND. NAM ALSO SUGGESTS A CEILING OF AROUND 6000
FEET AGL AFTER 21Z AND WILL ADD THIS IN A TEMPO GROUP. NO WEATHER
ANTICIPATED AT THIS TIME.
&&
.PREV DISCUSSION... /ISSUED 340 AM MST FRI NOV 18 2011/
SHORT TERM...MAIN CONCERN AGAIN FOR THE NEXT 24 HOURS IS THE STRONG
WIND POTENTIAL OVER THE MOUNTAINS AND FOOTHILLS AND SNOW SPREADING
INTO THE MOUNTAINS LATER TONIGHT. CURRENTLY A STRONG WESTERLY FLOW
ALOFT WITH SOME GUSTY WINDS IN THE MOUNTAINS AND FOOTHILLS. MOST OF
THE WINDS IN THE 15 TO 25 MPH WITH SOME HIGHER GUSTS IN THE 30-45
MPH RANGE. FOR MOST OF TODAY AND THIS EVENING...WINDS SHOULD REMAIN
BELOW HIGH WIND CRITERIA.
DEEP LOW PRESSURE WILL REMAIN OFF THE PACIFIC NORTHWEST COAST AND
SPIN OUT A WAVE WHICH WILL MOVE INTO COLORADO LATER TONIGHT. CROSS
SECTIONS SHOW CROSS BARRIER FLOW INCREASING LATER TONIGHT WITH
60-80KT COMING DOWN THE SLOPE AFTER 09Z. THIS SEEMS TO CORRESPOND
WITH STRONGER DOWNWARD VERTICAL VELOCITIES DEVELOPING BELOW 600MB
EARLY SAT AM. THIS MAY HELP IN AIDING THE STRONGEST WINDS TO THE
SURFACE. THERE IS A FAIRLY DECENT STABILITY THAT ALSO DEVELOPS AT
700MB. ON THE NEGATIVE SIDE FOR HIGH WINDS...THERE IS A FAIR AMOUNT
OF VERTICAL SHEAR WITH THE INCOMING JET AND MOISTURE/PRECIP
DEVELOPING IN THE MOUNTAINS MAY REDUCE THE AMPLIFICATION OF THE
WAVE. APPEARS LIKE THE WINDOW FOR THE STRONGEST WINDS WOULD BE
BETWEEN 09Z-15Z ON SATURDAY...AND FAVOR SOUTHERN SECTIONS INCLUDING
JEFFERSON...PARK AND WESTERN DOUGLAS COUNTIES AS THE FLOW IS A BIT
MORE SOUTHWEST. FOR NOW WITH STILL QUITE A BIT OF UNCERTAINTY...
WILL ONLY GO WITH A HIGH WIND WATCH GIVEN THE POTENTIAL FOR HIGH
WINDS AND WILL COVER ZONES 35>37 AND 41.
MOISTURE WILL SPREAD INTO THE MOUNTAINS LATER TONIGHT WITH SNOW
DEVELOPING...MAINLY OVER ZONE 31 AND 33. GIVEN THE STRONG SOUTHWEST
FLOW...ZONE 34 INCLUDING SUMMIT COUNTY WILL ONLY SEE SCATTERED SNOW
SHOWERS WITH UNPREFERRED OROGRAPHIC DIRECTION.
LONG TERM...JET MAX AND TROUGH AXIS WILL BE RIGHT OVER COLORADO
EARLY SATURDAY MORNING. CONCERN WILL CONTINUE TO BE HIGH WINDS
THROUGH THE MORNING FOR THE FOOTHILLS AND EASTERN SLOPES OF THE
NORTHERN AND CENTRAL MOUNTAINS AS WELL AS FOR SOUTH PARK AND SOME
AREAS OF THE PALMER DIVIDE. BY NOON...THE JET WILL LIFT NORTH...THE
SURFACE PRESSURE GRADIENT WILL RELAX AND THE COLD FRONT WILL MOVE
SOUTH ACROSS THE FORECAST AREA. THEREFORE WILL HAVE THE WATCH PERIOD
ONLY ENCOMPASS THE MORNING HOURS. WINDS BEHIND THE FRONT WILL BE
STRONG OUT OF THE NORTH AS WELL...HOWEVER NOT STRONG ENOUGH FOR ANY
HIGHLIGHT.
SNOW WILL CONTINUE OVER THE HIGH COUNTRY SATURDAY MORNING WITH
ANOTHER FEW INCHES EXPECTED. THE PARK AND NORTHERN GORE RANGES WILL
SEE THE HEAVIEST AMOUNTS WITH LESS EXPECTED SOUTH TOWARD THE I70
CORRIDOR. THE STRONG WINDS SATURDAY MORNING WILL CREATE AREAS OF
BLOWING SNOW ESPECIALLY OVER PASSES. THE STRONG MOUNTAIN LEVEL WINDS
ALONG WITH A LEESIDE SURFACE LOW OVER THE WESTERN PLAINS THROUGH THE
EVENING WILL KEEP THE PLAINS DRY AS WELL AS LESS SNOW AMOUNTS FOR
THE EASTERN SLOPES OF THE HIGHER MOUNTAINS AS WELL AS THE FOOTHILLS.
THIS LEESIDE LOW WILL ALSO KEEP TEMPERATURES WARMER THAN PREVIOUS
FORECASTS ESPECIALLY OVER THE WESTERN PLAINS. HAVE INCREASED THE
HIGHS INTO THE 50S FOR THE PLAINS. AS HIGH SURFACE PRESSURE FROM THE
NORTHERN GREAT PLAINS PUSHES DOWN INTO NORTHEASTERN COLORADO...THE
MOISTURE WILL NOT BE AVAILABLE ANYMORE FOR THE SHORT PERIOD OF
UPSLOPE FLOW TO PRODUCE ANYTHING.
SOUTHWEST FLOW WILL CONTINUE THROUGH MONDAY AS ANOTHER WEATHER
DISTURBANCE OUT OF THE DESERT SOUTHWEST TRANSITIONS OVER THE STATE
EARLY TUESDAY MORNING. ENOUGH MOISTURE IN THE FLOW WILL KEEP A
CHANCE OF SNOW OVER THE MOUNTAINS THROUGH THIS PERIOD. TEMPERATURES
SUNDAY AND MONDAY RIGHT AROUND NORMAL FOR THIS TIME WITH
TEMPERATURES IN THE UPPER 40S FOR THE PLAINS AND IN THE 30S FOR THE
MOUNTAINS. AS THE SECOND SYSTEM PASSES...MODELS ARE IN GOOD
AGREEMENT FOR TUESDAY THROUGH THANKSGIVING TO SEE WARMER THAN
AVERAGE TEMPERATURES AND DRY CONDITIONS AS AN UPPER RIDGE BUILDS IN.
MODELS ALSO AGREEING ON ANOTHER UPPER TROUGH TO PASS OVER THE STATE
THE NEXT DAY ON FRIDAY. THIS WILL LIKELY PRODUCE MORE SEASONAL
WEATHER INCLUDING MOUNTAIN SNOWS FOR THANKSGIVING WEEKEND.
AVIATION...VFR CONDITIONS EXPECTED THROUGH TONIGHT WITH JUST
VARYING AMOUNTS OF SCT-BKN HIGH LEVEL CLOUDS. TYPICAL DRAINAGE WINDS
FROM THE SOUTH EARLY THIS AM THEN A BIT OF A CHALLENGE THIS
AFTERNOON. DESPITE THE CURRENT SOUTHEAST AFTERNOON WINDS IN THE TAF
THINK THINGS MAY DEVELOP MORE LIKE YESTERDAY WITH SOME WESTERLY
WINDS SPILLING OUT BY MID-LATE AFTERNOON...ESP AT BJC AND DEN. WILL
ADJUST 12Z TAFS TO SHOW MORE OF THE SOUTHWEST TO WEST WINDS. THE
WEST TO SOUTHWEST WINDS WILL INCREASE AGAIN LATER TNT...ESP AT BJC
WITH GUSTS 30 TO 40KTS POSSIBLE.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM LATE TONIGHT THROUGH SATURDAY MORNING FOR
COZ035>037-041.
&&
$$
SHORT TERM...D-L
LONG TERM....KRIEDERMAN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
121 PM EST FRI NOV 18 2011
.SYNOPSIS...
HIGH PRESSURE WILL DOMINATE THE WEATHER OVER THE AREA THROUGH THE
WEEKEND INTO EARLY NEXT WEEK. LOW LEVEL EASTERLY FLOW MAY INCREASE
LOW CLOUDS OVER THE AREA OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
DRY HIGH PRESSURE CENTERED OVER NORTH CAROLINA WILL DOMINATE
TODAY. THE LATEST SATELLITE TRENDS AND THE MODELS INDICATED
CONTINUED CLEAR SKIES. THE TEMPERATURE GUIDANCE WAS CONSISTENT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
DRY RIDGING SHOULD CONTINUE TO DOMINATE TONIGHT. PRECIPITABLE
WATER VALUES WILL BE EXTREMELY LOW...LESS THAN A QUARTER INCH. EXPECT
LOWS IN THE UPPER 20S TO LOWER 30S UNDER STRONG RADIATIONAL
COOLING CONDITIONS. ONE POTENTIAL FLY IN THE OINTMENT OVERNIGHT
WILL BE THE POSSIBILITY OF STRATOCUMULUS MOVING IN OFF THE COAST
AS THE LOW LEVEL FLOW SHIFTS MORE SOUTHERLY ALLOWING ATLANTIC
MOISTURE TO OVERSPREAD THE REGION.
BY SATURDAY THE AIR MASS BEGINS TO MODIFY AND SURFACE HIGH PRESSURE
SHIFTS OFF THE COAST ALLOWING FOR A RETURN SOUTHERLY FLOW. UPPER
HEIGHTS WILL ALSO BE RISING IN RESPONSE TO TROUGHING UPSTREAM OVER
THE WESTERN PART OF THE COUNTRY. MAX TEMPERATURES SHOULD RISE BACK
INTO THE 60S SATURDAY AFTERNOON DESPITE SOME POSSIBLE CLOUD COVER.
LOW LEVEL FLOW OFF THE ATLANTIC WILL CONTINUE TO INCREASE
ATMOSPHERIC MOISTURE AS PRECIPITABLE WATER VALUES RETURN TO NEAR 1
INCH BY SUNDAY MORNING. PRE-DAWN STRATUS EARLY SUNDAY WILL LIMIT
THE AMOUNT OF COOLING AND THEREFORE EXPECT WARMER MIN TEMPERATURES
SATURDAY NIGHT. CONTINUED WARMING ON SUNDAY AS HIGHS PUSH INTO THE
LOWER 70S WITH WARM ADVECTION.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
WELL ABOVE NORMAL TEMPERATURES ARE EXPECTED MONDAY AND TUESDAY AS
UPPER HEIGHTS RISE AND SOUTHERLY FLOW AROUND THE SURFACE HIGH
BRINGS WARMER AIR NORTHWARD. TIMING FOR ANOTHER COLD FRONT
CROSSING THE AREA LOOKS TO BE TUESDAY NIGHT INTO WEDNESDAY
MORNING BRINGING THE NEXT CHANCE OF PRECIPITATION. FOR NOW POPS
WILL BE IN THE LOW CHANCE RANGE WITH THE FRONTAL PASSAGE. COLD
HIGH PRESSURE BUILDS INTO THE AREA BEHIND THE FRONT THURSDAY
PROVIDING DRY WEATHER AND BELOW NORMAL TEMPERATURES.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL MOVE EAST THIS EVENING. THIS WILL ALLOW 2 KFT
WINDS TO THE SOUTHEAST AND ADVECT MOISTURE INTO THE REGION LATE
TONIGHT AFTER MIDNIGHT. WILL KEEP MAINLY VFR CONDITIONS OVERNIGHT
AS AIRMASS REMAINS TO BE DRY. BOTH NAM AND RUC SHOW SOUTHEAST WINDS
BRINGING MOISTURE IN THE FORM OF CLOUDS AFTER MIDNIGHT. WILL KEEP
CLOUDS SCATTERED NEAR 2 KFT 06Z SOUTH LIKE AGS AND OGB AND 08Z TAF
SITES NORTH OF THERE. WITH DRY AIR...THINK CEILINGS WILL BE SLOW
TO DEVELOP. SO...DECIDED TO GO JUST SCATTERED UNTIL 12Z-14Z TIME
FRAME. WILL HAVE MVFR CEILINGS SOUTH TAF SITES OF OGB AND AGS
THEN MOVING NORTH TO REMAINING TAF SITES BY 14Z. THERE SHOULD BE
SOME WEAK ISENTROPIC LIFT AS WELL BUT MOIST LAYERS APPEARS TO BE
TOO SHALLOW TO GIVE ANY PRECIPITATION SATURDAY. AIRMASS NEAR THE
SURFACE APPEARS TO BE TOO DRY FOR ANY FOG SATURDAY MORNING. DEWPOINTS
IN THE TEENS EARLY TONIGHT REBOUND TO THE 20S AFTER MIDNIGHT BUT
STILL TOO LOW FOR FOG DEVELOPMENT.
EXTENDED AVIATION OUTLOOK...MOISTURE ASSOCIATED WITH AN ONSHORE
FLOW MAY HELP CAUSE PERIODS OF MVFR CONDITIONS SATURDAY AND IFR
TO MVFR CONDITIONS SUNDAY THROUGH TUESDAY...MAINLY DURING THE EARLY
MORNING HOURS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1239 PM EST FRI NOV 18 2011
.SYNOPSIS...
HIGH PRESSURE WILL DOMINATE THE WEATHER OVER THE AREA THROUGH THE
WEEKEND INTO EARLY NEXT WEEK. LOW LEVEL EASTERLY FLOW MAY INCREASE
LOW CLOUDS OVER THE AREA OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
DRY HIGH PRESSURE CENTERED OVER NORTH CAROLINA WILL DOMINATE
TODAY. THE LATEST SATELLITE TRENDS AND THE MODELS INDICATED
CONTINUED CLEAR SKIES. THE TEMPERATURE GUIDANCE WAS CONSISTENT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
DRY RIDGING SHOULD CONTINUE TO DOMINATE TONIGHT. PRECIPITABLE
WATER VALUES WILL BE EXTREMELY LOW...LESS THAN A QUARTER INCH. EXPECT
LOWS IN THE UPPER 20S TO LOWER 30S UNDER STRONG RADIATIONAL
COOLING CONDITIONS. ONE POTENTIAL FLY IN THE OINTMENT OVERNIGHT
WILL BE THE POSSIBILITY OF STRATOCUMULUS MOVING IN OFF THE COAST
AS THE LOW LEVEL FLOW SHIFTS MORE SOUTHERLY ALLOWING ATLANTIC
MOISTURE TO OVERSPREAD THE REGION.
BY SATURDAY THE AIR MASS BEGINS TO MODIFY AND SURFACE HIGH PRESSURE
SHIFTS OFF THE COAST ALLOWING FOR A RETURN SOUTHERLY FLOW. UPPER
HEIGHTS WILL ALSO BE RISING IN RESPONSE TO TROUGHING UPSTREAM OVER
THE WESTERN PART OF THE COUNTRY. MAX TEMPERATURES SHOULD RISE BACK
INTO THE 60S SATURDAY AFTERNOON DESPITE SOME POSSIBLE CLOUD COVER.
LOW LEVEL FLOW OFF THE ATLANTIC WILL CONTINUE TO INCREASE
ATMOSPHERIC MOISTURE AS PRECIPITABLE WATER VALUES RETURN TO NEAR 1
INCH BY SUNDAY MORNING. PRE-DAWN STRATUS EARLY SUNDAY WILL LIMIT
THE AMOUNT OF COOLING AND THEREFORE EXPECT WARMER MIN TEMPERATURES
SATURDAY NIGHT. CONTINUED WARMING ON SUNDAY AS HIGHS PUSH INTO THE
LOWER 70S WITH WARM ADVECTION.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
WELL ABOVE NORMAL TEMPERATURES ARE EXPECTED MONDAY AND TUESDAY AS
UPPER HEIGHTS RISE AND SOUTHERLY FLOW AROUND THE SURFACE HIGH
BRINGS WARMER AIR NORTHWARD. TIMING FOR ANOTHER COLD FRONT
CROSSING THE AREA LOOKS TO BE TUESDAY NIGHT INTO WEDNESDAY
MORNING BRINGING THE NEXT CHANCE OF PRECIPITATION. FOR NOW POPS
WILL BE IN THE LOW CHANCE RANGE WITH THE FRONTAL PASSAGE. COLD
HIGH PRESSURE BUILDS INTO THE AREA BEHIND THE FRONT THURSDAY
PROVIDING DRY WEATHER AND BELOW NORMAL TEMPERATURES.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL MOVE EAST THIS EVENING. THIS WILL ALLOW 2 KFT
WINDS TO THE SOUTHEAST AND ADVECT MOISTURE INTO THE REGION LATE
TONIGHT AFTER MIDNIGHT. WILL KEEP MAINLY VFR CONDITIONS OVERNIGHT
AS AIRMASS REMAINS TO BE DRY. BOTH NAM AND RUC SHOW SOUTHEAST WINDS
BRINGING MOISTURE IN THE FORM OF CLOUDS AFTER MIDNIGHT. WILL KEEP
CLOUDS SCATTERED NEAR 2 KFT 06Z SOUTH LIKE AGS AND OGB AND 08Z TAF
SITES NORTH OF THERE. WITH DRY AIR...THINK CEILINGS WILL BE SLOW
TO DEVELOP. SO...DECIDED TO GO JUST SCATTERED UNTIL 12Z-14Z TIME
FRAME. WILL HAVE MVFR CEILINGS SOUTH TAF SITES OF OGB AND AGS
THEN MOVING NORTH TO REMAINING TAF SITES BY 14Z. THERE SHOULD BE
SOME WEAK ISENTROPIC LIFT AS WELL BUT MOIST LAYERS APPEARS TO BE
TOO SHALLOW TO GIVE ANY PRECIPITATION SATURDAY. AIRMASS NEAR THE
SURFACE APPEARS TO BE TOO DRY FOR ANY FOG SATURDAY MORNING. DEWPOINTS
IN THE TEENS EARLY TONIGHT REBOUND TO THE 20S AFTER MIDNIGHT BUT
STILL TOO LOW FOR FOG DEVELOPMENT.
EXTENDED AVIATION OUTLOOK...MOISTURE ASSOCIATED WITH AN ONSHORE
FLOW MAY HELP CAUSE PERIODS OF MVFR CONDITIONS SATURDAY AND IFR
TO MVFR CONDITIONS SUNDAY THROUGH TUESDAY...MAINLY DURING THE EARLY
MORNING HOURS.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...07
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1124 AM CST FRI NOV 18 2011
.AVIATION...
VFR WX WILL BE SEEN THROUGH 12Z/19 AND LIKELY 18Z/19. RUC MODEL
INDICATES THE INVERSION MIXING TO ABOUT 3KFT AGL. SOME MOMENTUM
TRANSFER FROM ALOFT IS OCCURRING WHICH IS LIKELY RESULTING IN LOW
LEVEL TURBULENCE DUE TO MIXING. THE INVERSION BEGINS TO RE-
ESTABLISH BY 00Z/19 SO WINDS WL DECREASE AFT 22Z/18. AFT 00Z/19 MODELS
GENERALLY SHOW 30-35 KTS ARND 2KFT AGL WHICH COULD RESULT IN LLWS
BUT SHEAR VALUES ARE MARGINAL ARND 20 KTS. A SCT TO BKN DECK AT
4-6KFT AGL SHOULD DVLP AFT 12Z/19 AS MOISTURE ADVECTS IN.
..08..
&&
.PREV DISCUSSION... /ISSUED 1054 AM CST FRI NOV 18 2011/
UPDATE...
A FAIRLY SUBSTANTIAL UPDATE TO THE FCST HAS BEEN DONE BASED ON
SATELLITE AND SFC OBS TRENDS THROUGH MID MORNING.
A WEAK SHORTWAVE MOVING THROUGH IN THE FLOW ALOFT HAS HELPED
GENERATE OPAQUE CI/CS THAT IS HELPING TO SUPPRESS TEMPERATURES.
RUC TRENDS SHOW THIS SHORTWAVE EXITING THE AREA DURING THE
AFTERNOON SO SKIES WILL EVENTUALLY CLEAR.
THE MORE SUBSTANTIAL CLOUD COVER IS HELPING TO SUPPRESS
TEMPERATURES IN SPITE OF THE WAA THAT IS OCCURRING. RUC TRENDS
NOW INDICATE THE INVERSION ONLY MIXING TO AROUND 900MB. THIS LOWER
MIXING HEIGHT COMBINED WITH MORE CLOUDS WILL RESULT IN
TEMPERATURES BEING A BIT LOWER THAN FCST. ADDITIONALLY...THE LOWER
MIXING HEIGHT WILL NOT MIX DOWN AS MUCH HIGHER MOMENTUM AIR ALOFT.
WINDY CONDITIONS WILL BE SEEN BUT NO HEADLINES APPEAR WARRANTED.
THE MODELS EITHER VERIFIED OR INITIALIZED TOO MOIST IN THE LOWER
LEVELS BASED ON 12Z UA DATA. THIS MOIST BIAS WILL PLAY INTO THE
FCST FOR TONIGHT AND SATURDAY WHICH WILL BE DISCUSSED MORE
THOROUGHLY IN THE AFTERNOON DISCUSSION.
AN UPDATED FCST HAS BEEN SENT.
.08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1054 AM CST FRI NOV 18 2011
.UPDATE...
A FAIRLY SUBSTANTIAL UPDATE TO THE FCST HAS BEEN DONE BASED ON
SATELLITE AND SFC OBS TRENDS THROUGH MID MORNING.
A WEAK SHORTWAVE MOVING THROUGH IN THE FLOW ALOFT HAS HELPED
GENERATE OPAQUE CI/CS THAT IS HELPING TO SUPPRESS TEMPERATURES.
RUC TRENDS SHOW THIS SHORTWAVE EXITING THE AREA DURING THE
AFTERNOON SO SKIES WILL EVENTUALLY CLEAR.
THE MORE SUBSTANTIAL CLOUD COVER IS HELPING TO SUPPRESS
TEMPERATURES IN SPITE OF THE WAA THAT IS OCCURRING. RUC TRENDS
NOW INDICATE THE INVERSION ONLY MIXING TO AROUND 900MB. THIS LOWER
MIXING HEIGHT COMBINED WITH MORE CLOUDS WILL RESULT IN
TEMPERATURES BEING A BIT LOWER THAN FCST. ADDITIONALLY...THE LOWER
MIXING HEIGHT WILL NOT MIX DOWN AS MUCH HIGHER MOMENTUM AIR ALOFT.
WINDY CONDITIONS WILL BE SEEN BUT NO HEADLINES APPEAR WARRANTED.
THE MODELS EITHER VERIFIED OR INITIALIZED TOO MOIST IN THE LOWER
LEVELS BASED ON 12Z UA DATA. THIS MOIST BIAS WILL PLAY INTO THE
FCST FOR TONIGHT AND SATURDAY WHICH WILL BE DISCUSSED MORE
THOROUGHLY IN THE AFTERNOON DISCUSSION.
AN UPDATED FCST HAS BEEN SENT.
..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
729 PM EST SAT NOV 19 2011
.SYNOPSIS...
HIGH PRESSURE PUSHES FARTHER OUT TO SEA TONIGHT AND SUNDAY. A
FRONT WILL APPROACH FROM THE NORTHWEST LATE SUNDAY...AND BECOME
NEARLY STATIONARY OVER THE REGION MONDAY AND MONDAY NIGHT. THE
FRONT WILL LIFT NORTH OF THE AREA AS A WARM FRONT ON TUESDAY. A
COLD FRONT WILL THEN PUSH THROUGH THE MID ATLANTIC STATES ON
WEDNESDAY...WITH HIGH PRESSURE BUILDING IN FROM THE WEST
THANKSGIVING DAY INTO NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
FOR THE 7 PM UPDATE...ONLY MADE SOME MINOR CHANGES TO SKY COVER
AND TEMPERATURES. TEMPERATURES ARE A BIT LOWER THAN FORECAST
ACROSS INTERIOR PORTIONS OF SE VIRGINIA (SUFFOLK AREA) AND WARMER
ACROSS THE EASTERN SHORE. LOW TEMPERATURES WERE RAISED ABOUT 3
DEGREES ON THE EASTERN SHORE AND WILL BE IN THE MID TO UPPER 40S
EXCEPT AROUND 50 NEAR THE COAST. SKY COVER WAS INCREASED SOME TO
ACCOUNT FOR CIRRUS THAT IS MOST PREVALENT OVER OUR NORTHERN AREAS
AND SOME EXPECTED STRATUS IN THE MORNING OVER NE NORTH CAROLINA
AND EXTREME SE VIRGINIA.
PREVIOUS DISCUSSION...
CURRENT SFC ANALYSIS SHOWS HIGH PRESSURE CENTERED WELL OFF THE
DELMARVA COAST. RETURN SW FLOW AROUND THE BACKSIDE OF THE HIGH HAS
PROVIDED A MILDER DAY ACROSS THE FCST REGION...WHILE ALSO BRINGING
PERIODIC WAA CLOUDINESS (MAINLY UPPER LEVEL). LLVL TRAJECTORIES
OUT OF THE GULF STREAM (BTWN ILM-MHX) DID PROVIDE A PERIOD OF
ENHANCED LLVL THETA-E WITH THE HIGHER DWPTS...WHICH IN TURN LED TO
THE DEVELOPMENT OF A SHALLOW STRATO-CU DECK THAT PERSISTED FOR A
WHILE FROM THE LATE AM INTO EARLY AFTN HRS BEFORE MIXING OUT.
FOR THE OVERNIGHT HOURS...THE MAIN FCST CHALLENGE WILL BE WITH
CLOUD COVER...ESPECIALLY REGARDING THE DEVELOPMENT OF ANY LOWER
CLOUD DECKS (STRATUS LAYERS) WITH THE LIGHT S/SW FLOW. BOTH THE
GFS/NAM AS WELL AS THE RUC FCST SOUNDINGS ALL SHOW A HIGH
POTENTIAL FOR THE DEVELOPMENT OF A LOWER CLOUD DECK...WITH A
STRONG SFC-BASED INVERSION WITH TEMPS AS WELL AS MIXING RATIO
(MSTR) THROUGH 1000-975 MB. HOWEVER...MOST OF THE NUMERICAL
GUIDANCE IS NOT PICKING UP ON THESE CLOUDS...THOUGH PER THE FCST
SOUNDINGS...OTHER LOWER LAYER MSTR (BTWN 900-800 MB) IS NOTED...
PARTICULARLY E OF I-95. THE UPSHOT IS LOWER THAN AVERAGE
CONFIDENCE IN TERMS OF THE SKY FCST OVERNIGHT...THOUGH BELIEVE
THERE IS ENOUGH EVIDENCE TO GO WITH A TREND TOWARD MOSTLY CLOUDY
LATE TONIGHT/EARLY SUN. LOWS NOT AS COLD COMPARED TO THE LAST
COUPLE NIGHTS...GIVEN THE CLOUD COVER AND S/SW FLOW UNDER 10 KTS.
MIN TEMPS GENERALLY THROUGH THE 40S.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
MID/UPR LVL FLO WILL BECOME MORE ZNL ACRS THE FA LATER SUN THRU
MON. THE RESULT WILL BE A FRNTL BNDRY THAT WILL DROP INTO THE AREA
TO NEAR THE VA/NC BORDER. THERE WILL BE MORE CLDS ACRS THE NRN/NW
CNTIES BY LATE IN THE DAY...AS THE FRNT APPROACHES FM THE NW.
OTHRWISE...DRY AND MILD CONDITIONS WILL PREVAIL ON SUN WITH MUCH
OF THE REGION GENERALLY PRTLY SNY. MAX TEMPS WILL BE IN THE MID TO
UPR 60S MOST LOCATIONS...THOUGH CANNOT RULE OUT 70+ READINGS OVER
THE FAR SRN PTNS (ALONG/S OF THE VA/NC BORDER) WITH THE GREATER
AMOUNT OF SUNSHINE.
SFC FRNTL BNDRY THEN DROPS INTO THE AREA SUN NGT THRU MON...
STALLING NEAR THE VA/NC BORDER BY LATE MON. GOING WITH HIEST POPS
NEAR 50 PERCENT ACRS THE N-NW 1/3 OF THE AREA LATE SUN NGT AND
MON...DECREASING TO SLGT CHC POPS OVR SRN 1/3 OF THE REGION. LOWS
SUN NGT IN THE UPR 40S TO MID 50S. HIGHS ON MON QUITE VARIABLE
ONCE AGAIN...FROM THE UPPER 50S/NEAR 60 TO LOWER 70S OVER SRN
VA/NERN NC. BECMG MSTLY CLDY OR CLDY SUN NGT...AND MSTLY CLDY OR
CLDY ON MON.
STALLED FRONTAL BOUNDARY ACROSS RGN MONDAY NIGHT SLOWLY LIFTS N
AS A WARM FRONT TUESDAY IN RESPONSE TO LOW PRESSURE APPROACHING
FROM THE W. WILL KEEP CHC POPS IN FCST ON TUE...AGAIN WITH THE
HIGHEST CHANCES OVER THE NRN TIER. LOWS TUE AM IN U40S-M50S...
HIGHS FROM THE M60S FAR N TO THE L70S S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
FOLLOWING THE SLOWER ECMWF SOLN WRT THE COLD FRNTL PASSAGE WED.
LOW PRS MOVES NE THRU OHIO VLLY TUE NITE WITH ASSCTD WRM FRONT
LIFTG N ACROSS THE AREA. MILD WITH CHC SHWRS. LOWS IN THE 50S
AS FA BECOMES WRM SCTRD. TRAILING COLD FRONT CROSSES FA WED AFTRN
THEN EXITS OFFSHORE WED EVE. AGAIN THIS THE SLOWER SOLN THAN GFS
WHICH HAS A FROPA WED MORN. KEPT CHC POPS ATTM BUT ADDED THUNDER
AS DATA SUGGESTS MRGINAL INSTAB AHEAD OF BNDRY. HIGHS IN THE 60S
TO NR 70.
LINGERING SHWRS ALONG THE COAST WED EVE...FOLLOWED BY STRNG CAA
WED NITE INTO THURSDAY AS LOW PRS DEEPENS TO THE NE AND 1030MB
HIGH PRS BLDG INTO RGN FROM W. DRY BUT COOL THUR AND FRI. HIGHS
THU 50-55...M-U50S FRI. LOWS IN THE 30S. DRY AND MILDER SAT WITH
MORE CLOUD COVER. HIGHS U50S-L60S.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
FORECAST WAS A BIT OF A CHALLENGE CONCERNING ANY STRATUS AND FOG
OVERNIGHT. AFTER LOOKING AT DATA FROM VARIOUS MODELS...MAINLY USED
NAM BUFKIT SOUNDINGS AS A BASIS FOR THIS FCST. ALTHOUGH STRONG SW
WINDS ARE FORECAST A FEW THOUSAND FEET...SW (AS OPPOSED TO S/SE)
WINDS SHOULD KEEP THE BOUNDARY LAYER FAIRLY DRY. THE ONLY
EXCEPTION WOULD BE ECG WHERE NAM IS MORE BULLISH WITH LOW LEVEL
MOISTURE. SOUNDINGS APPEAR TO SUPPORT FOG MORE THAN STRATUS...
HOWEVER THE STRONG WINDS JUST OFF THE SURFACE AS WELL AS A BROKEN
CIRRUS LAYER WILL HINDER FOG FORMATION. THE MAVMOS CATEGORIES LOOK
REASONABLE AND INCLUDES IFR FOR VSBY AT ECG.
MIXING SHOULD TURN CONDITIONS TO VFR BY LATE MORNING SUNDAY AND
THERE IS LITTLE ELSE TO CONSIDER WITH THIS TAF PERIOD.
OUTLOOK...MVFR/IFR CONDITIONS WILL BE PSBL MONDAY MORNING WITH AREAS
OF PCPN AND LOWER CEILINGS AS A FRONT APPROACHING FROM THE NORTH. A
BETTER CHANCE FOR WIDESPREAD PCPN AND IFR CONDITIONS APPEAR TO BE IN
THE FUTURE AROUND TUESDAY NIGHT AND WEDNESDAY AS A LOW PRESSURE
SYSTEM MOVES THROUGH THE AREA. CONDITIONS ARE FORECAST TO IMPROVE BY
THURSDAY.
&&
.MARINE...
NO FLAGS THRU THE WEEKEND AS HIGH PRS PARKS ITSELF OFF THE SERN
COAST. RETURN S-SW FLOW AOB 15 KTS THRU SUN NIGHT. SEAS 2-3 FT.
BACKDOOR TYPE COLD FRONT SAGS S ACROSS MID ATLNTC COAST MON BUT
A QSTN IS TO HOW FAR S THE BNDRY ACTUALLY GETS. WINDS SHFT INTO
N-NE BY MON AFTRN BUT LTST DATA KEEPS CONDITIONS BLO SCA LVLS.
THIS BNDRY PROGGED TO LIFT BACK N AS A WARM FRONT TUE NITE IN
RESPONSE TO LOW PRS APPRCHG FROM THE S. NXT CHC FOR FLAGS COMES
WED INTO THU AS S WNDS INCRS AHEAD AHEAD OF CDFRNT. STRNG CAA
PROGGED BEHIND BNDRY WED NITE INTO THU. MAY EVEN SEE NW GALES
WITH THIS EVENT BUT CAPPED GUSTS AT 30 KTS FOR NOW.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BKH
NEAR TERM...BKH/LSA
SHORT TERM...BKH
LONG TERM...MPR
AVIATION...LSA
MARINE...MPR
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1233 PM EST FRI NOV 18 2011
UPDATED AVIATION DISCUSSION FOR 18Z TAFS
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS
THE CONUS. SEVERAL WEAK SHORTWAVES WERE EMBEDDED IN THE WRLY FLOW
OVER THE NRN PLAINS AND ADJOINING PORTIONS OF SRN CANADA. A STRONGER
UPPER LEVEL JET AND SHORTWAVE TROUGH THAT WILL IMPACT WEATHER
SATURDAY WAS MOVING INTO THE PAC NW. RADAR RETURNS OVER NRN WI AND
SW UPPER MI WERE INCREASING AS WAA AND ISENTROPIC ASCENT INCREASED
AHEAD OF A SFC TROUGH OVER THE PLAINS. SFC OBS INDICATED THAT THE
PCPN WAS MAINLY ALOFT.
&&
.DISCUSSION...
TODAY AND TONIGHT...THE NAM/GFS SHOW A BAND OF 285-295K ISENTROPIC
LIFT MOVING ACROSS UPPER MI. HOWEVER...THE NAM DEPICTION OF
SLOWER/LESS SATURATION IN THE LOWER LEVELS (BELOW 850 MB) LOOKS MORE
REALISTIC GIVEN UPSTREAM OBS/SOUNDINGS. SO...EXPECT ANY PCPN WILL
BE MORE LIGHT/PATCHY AND ONLY SLIGHT CHANCE TO CHANCE POPS WERE
INCLUDED. AS ANOTHER WEAK SHORTWAVE AND ASSOCIATED AREA OF 700-600 MB
FGEN MOVES INTO WRN LAKE SUPERIOR AND WRN UPPER MI LATE TODAY AND
THIS EVENING...SOME PATCHY LIGHT SNOW OR FLURRIES MAY ALSO PERSIST
INTO THE FAR WEST.
SATURDAY AND SATURDAY NIGHT...A FAST MOVING WAVE IS EXPECTED TO MOVE
FROM THE CENTRAL PLAINS SATURDAY MORNING TO NEAR THE STRAITS BY LATE
SATURDAY EVENING. THE GFS/NAM/ECMWF WERE IN REASONABLE AGREEMENT
WITH THE TRACK OF THE SFC LOW. HOWEVER...SINCE THERE HAS
BEEN SIGNIFICANT VARIATION WITH THE POSITION/STRENGTH OF THE
STRONGEST 800-600 MB FGEN AND THE STRUCTURE/PLACEMENT OF THE COUPLED
UPPER LEVEL JET...CONFIDENCE IN WHERE ANY HEAVY BANDS OF SNOW WILL
SET UP IS LIMITED. MODELS CONSENSUS STILL SUGGESTS THE STRONGER
DYNAMICS WILL AFFECT THE WEST HALF OF UPPER MI. SYNOPTIC QPF AMOUNTS
OF 0.25 TO 0.50 INCH STILL SEEM REASONABLE GIVEN 4 G/KG MOISTURE
AVBL AND THE PERIOD OF STRONG FORCING. SNOW/WATER RATIO VALUES ARE
LIKELY TO REMAIN NEAR OR EVEN BELOW 10/1 WITH THE STRONGER UPWARD
MOTION BELOW THE -12C TO -15C LAYER. ADDITIONAL UPSLOPE AND LAKE
ENHANCEMENT IS EXPECTED NEAR IWD AND OVER N CNTRL UPPER MI.
HOWEVER...THE WINDOW FOR HEAVIER SNOW DURING THE PERIOD OF SYNOPTIC
FORCING IS RELATIVELY SHORT. GIVEN THE AMOUNT OF UNCERTAINTY AND WITH
OVERALL SNOWFALL AMOUNTS EXPECTED TO REMAIN MAINLY IN THE 3 TO 7
INCH RANGE BTWN 18Z SAT AND 12Z SUN AN SPS RATHER THAN A WATCH WAS
ISSUED. A NAM/GFS BLEND OF LOW LEVEL THICKNESS/WET BULB ZERO HEIGHTS
WERE USED FOR PLACEMENT OF THE RAIN SNOW LINE FROM ABOUT KP53 TO JUST
SE OF KIMT.
SUNDAY....N TO NNW WINDS 850 MB TEMP TO AROUND -11C SHOULD KEEP SOME
SCT -SHSN GOING IN THE MORNING. AS THE SFC RIDGE BUILDS INTO THE
AREA IN THE AFTERNOON ALONG WITH DRIER AIR AND LOWER INVERSION
HEIGHTS...ANY REMAINING LES WILL TAPER OFF.
FOR THE EXTENDED...SFC TROUGH SLIDES ACROSS MAINLY LK SUPERIOR ON
MONDAY LEADING TO WARM AIR ADVECTION ALOFT AND SOME ISENTROPIC LIFT.
GFS/CANADIAN FAVOR A PERIOD OF LGT SNOW MONDAY BUT FOR MOST PART THE
ECMWF REMAINS DRY. GFS FCST SOUNDINGS SHOW DEEP MOISTURE AND LIFT
ACTING UPON FAVORABLE TEMPS FOR SNOW INITIATION...SO AT LEAST THE
GFS QPF IS CONSISTENT WITH ITS OTHER MODEL FIELDS. SHORTWAVE IS FCST
TO TRACK MAINLY ACROSS LK SUPERIOR AND WOULD EXPECT GREATEST CHANCE
OF SATURATION/PCPN TO OCCUR THERE AS WELL. ONLY HAVE CHANCE POPS ON
THE KEWEENAW. EVEN IF GFS IS CORRECT...WOULD ONLY SEE SUB ADVY SNOW
AMOUNTS...AND THAT IS PRETTY GENEROUS. AFTER TROUGH EXITS...LOOKS
LIKE A QUIET PERIOD OF WEATHER OVR UPR LAKES LEADING INTO THE
THANKSGIVING HOLIDAY AS WRLY FLOW KEEPS MAIN STORM TRACK SUPPRESSED
TO SOUTH. MAY BE A SYSTEM THAT AFFECTS LOWER MICHIGAN LATER TUESDAY
INTO TUESDAY NIGHT...BUT THAT SHOULD BE GONE BY THE BUSY WEDNESDAY
TRAVEL DAY WITH HIGH PRESSURE BUILDING OVR UPR LAKES REGION.
SEEMS LIKE NICE WARMUP COULD OCCUR ON THANKSGIVING ONCE THE HIGH
MOVES EAST LEADING TO RETURN SW FLOW AT SFC. GFS SOUNDINGS SHOW
LOWER INVERSION BUT EVEN LIMITED MIXING YIELDS HIGHS WELL INTO THE
40S. GIVEN THE SW WINDS...INCREASED TEMPS FOR DOWNSLOPE AREAS NEAR
LK SUPERIOR TOWARD 50 DEGREES...CLOSER TO BIAS CORRECTED CONSENSUS.
LOOKS LIKE VERY NICE WEATHER FOR THE THANKSGIVING HOLIDAY...AND
LIKELY INTO FRIDAY TOO AS SW WINDS CONTINUE TO PUSH WARM AIR INTO
THE UPR LAKES AHEAD OF DEVELOPING TROUGH OVR THE PLAINS. RECORD
HIGHS FOR 24-25 NOVEMBER ARE MAINLY IN THE MID TO UPR 50S ACROSS THE
CWA.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/...
VFR CONDITIONS ARE EXPECTED THROUGH THIS EVENING AT ALL SITES. BY
LATE TONIGHT...PASSAGE OF WEAK LOW PRESSURE TROUGH MAY RESULT IN
CIGS BECOMING MVFR AT KIWD AND KCMX.
CONDITIONS WILL DETERIORATE LATE TONIGHT THROUGH SATURDAY AS A LOW
PRESSURE SYSTEM MOVES SOUTHEAST OF THE AREA. WIDESPREAD IFR/LIFR
CONDITIONS ARE EXPECTED BEGINNING SATURDAY AFTN AT ALL THREE TAF
SITES AS WIDESPREAD/STEADY WET SNOW WORKS ACROSS MOST OF UPPER
MICHIGAN. CONDITIONS WILL NOT IMPROVE UNTIL SUNDAY MORNING AS THE
LOW MOVES AWAY FROM THE AREA.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
WEST-TO-EAST ORIENTED SFC TROUGH PASSES ACROSS LK SUPERIOR TODAY
LEADING TO DEVELOPING SE WINDS OVR WESTERN LK AND GUSTY SOUTHERLY
WINDS TO 30 KTS OVER EASTERN SECTIONS. WINDS DIMINISH TONIGHT...THEN
INCREASE BY LATE SATURDAY WITH ARRIVAL OF LOW PRESSURE SYSTEM FM THE
SOUTHERN PLAINS. SFC LOW NOT FCST TO DEEPEN SIGNIFICANTLY BUT THERE
IS DECENT COLD AIR RUSHING IN FM THE NORTH IN WAKE OF THE SYSTEM.
CANNOT RULE OUT LOW END NORTHERLY GALES SATURDAY NIGHT OVER CNTRL LK
SUPERIOR. NOT NEAR ENOUGH CONFIDENCE TO ISSUE GALE WATCH AT THIS
POINT THOUGH. SHOULD BE A WIDESPREAD SNOW OVER MOST OF LK SUPERIOR
AS THE LOW MOVES THROUGH THE AREA. LOW THEN QUICKLY SLIDES EAST
SUNDAY AND WINDS DIMINISH BY SUNDAY AFTN. WINDS SHOULD STAY LESS
THAN 25 KTS EARLY NEXT WEEK AS A WEAK TROUGH MOVES ACROSS FOLLOWED
BY A LARGE AREA OF HIGH PRESSURE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
DISCUSSION...JLB
AVIATION...TITUS
MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
655 AM EST FRI NOV 18 2011
UPDATED AVIATION DISCUSSION FOR 12Z TAFS
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS
THE CONUS. SEVERAL WEAK SHORTWAVES WERE EMBEDDED IN THE WRLY FLOW
OVER THE NRN PLAINS AND ADJOINING PORTIONS OF SRN CANADA. A STRONGER
UPPER LEVEL JET AND SHORTWAVE TROUGH THAT WILL IMPACT WEATHER
SATURDAY WAS MOVING INTO THE PAC NW. RADAR RETURNS OVER NRN WI AND
SW UPPER MI WERE INCREASING AS WAA AND ISENTROPIC ASCENT INCREASED
AHEAD OF A SFC TROUGH OVER THE PLAINS. SFC OBS INDICATED THAT THE
PCPN WAS MAINLY ALOFT.
&&
.DISCUSSION...
TODAY AND TONIGHT...THE NAM/GFS SHOW A BAND OF 285-295K ISENTROPIC
LIFT MOVING ACROSS UPPER MI. HOWEVER...THE NAM DEPICTION OF
SLOWER/LESS SATURATION IN THE LOWER LEVELS (BELOW 850 MB) LOOKS MORE
REALISTIC GIVEN UPSTREAM OBS/SOUNDINGS. SO...EXPECT ANY PCPN WILL
BE MORE LIGHT/PATCHY AND ONLY SLIGHT CHANCE TO CHANCE POPS WERE
INCLUDED. AS ANOTHER WEAK SHORTWAVE AND ASSOCIATED AREA OF 700-600 MB
FGEN MOVES INTO WRN LAKE SUPERIOR AND WRN UPPER MI LATE TODAY AND
THIS EVENING...SOME PATCHY LIGHT SNOW OR FLURRIES MAY ALSO PERSIST
INTO THE FAR WEST.
SATURDAY AND SATURDAY NIGHT...A FAST MOVING WAVE IS EXPECTED TO MOVE
FROM THE CENTRAL PLAINS SATURDAY MORNING TO NEAR THE STRAITS BY LATE
SATURDAY EVENING. THE GFS/NAM/ECMWF WERE IN REASONABLE AGREEMENT
WITH THE TRACK OF THE SFC LOW. HOWEVER...SINCE THERE HAS
BEEN SIGNIFICANT VARIATION WITH THE POSITION/STRENGTH OF THE
STRONGEST 800-600 MB FGEN AND THE STRUCTURE/PLACEMENT OF THE COUPLED
UPPER LEVEL JET...CONFIDENCE IN WHERE ANY HEAVY BANDS OF SNOW WILL
SET UP IS LIMITED. MODELS CONSENSUS STILL SUGGESTS THE STRONGER
DYNAMICS WILL AFFECT THE WEST HALF OF UPPER MI. SYNOPTIC QPF AMOUNTS
OF 0.25 TO 0.50 INCH STILL SEEM REASONABLE GIVEN 4 G/KG MOISTURE
AVBL AND THE PERIOD OF STRONG FORCING. SNOW/WATER RATIO VALUES ARE
LIKELY TO REMAIN NEAR OR EVEN BELOW 10/1 WITH THE STRONGER UPWARD
MOTION BELOW THE -12C TO -15C LAYER. ADDITIONAL UPSLOPE AND LAKE
ENHANCEMENT IS EXPECTED NEAR IWD AND OVER N CNTRL UPPER MI.
HOWEVER...THE WINDOW FOR HEAVIER SNOW DURING THE PERIOD OF SYNOPTIC
FORCING IS RELATIVELY SHORT. GIVEN THE AMOUNT OF UNCERTAINTY AND WITH
OVERALL SNOWFALL AMOUNTS EXPECTED TO REMAIN MAINLY IN THE 3 TO 7
INCH RANGE BTWN 18Z SAT AND 12Z SUN AN SPS RATHER THAN A WATCH WAS
ISSUED. A NAM/GFS BLEND OF LOW LEVEL THICKNESS/WET BULB ZERO HEIGHTS
WERE USED FOR PLACEMENT OF THE RAIN SNOW LINE FROM ABOUT KP53 TO JUST
SE OF KIMT.
SUNDAY....N TO NNW WINDS 850 MB TEMP TO AROUND -11C SHOULD KEEP SOME
SCT -SHSN GOING IN THE MORNING. AS THE SFC RIDGE BUILDS INTO THE
AREA IN THE AFTERNOON ALONG WITH DRIER AIR AND LOWER INVERSION
HEIGHTS...ANY REMAINING LES WILL TAPER OFF.
FOR THE EXTENDED...SFC TROUGH SLIDES ACROSS MAINLY LK SUPERIOR ON
MONDAY LEADING TO WARM AIR ADVECTION ALOFT AND SOME ISENTROPIC LIFT.
GFS/CANADIAN FAVOR A PERIOD OF LGT SNOW MONDAY BUT FOR MOST PART THE
ECMWF REMAINS DRY. GFS FCST SOUNDINGS SHOW DEEP MOISTURE AND LIFT
ACTING UPON FAVORABLE TEMPS FOR SNOW INITIATION...SO AT LEAST THE
GFS QPF IS CONSISTENT WITH ITS OTHER MODEL FIELDS. SHORTWAVE IS FCST
TO TRACK MAINLY ACROSS LK SUPERIOR AND WOULD EXPECT GREATEST CHANCE
OF SATURATION/PCPN TO OCCUR THERE AS WELL. ONLY HAVE CHANCE POPS ON
THE KEWEENAW. EVEN IF GFS IS CORRECT...WOULD ONLY SEE SUB ADVY SNOW
AMOUNTS...AND THAT IS PRETTY GENEROUS. AFTER TROUGH EXITS...LOOKS
LIKE A QUIET PERIOD OF WEATHER OVR UPR LAKES LEADING INTO THE
THANKSGIVING HOLIDAY AS WRLY FLOW KEEPS MAIN STORM TRACK SUPPRESSED
TO SOUTH. MAY BE A SYSTEM THAT AFFECTS LOWER MICHIGAN LATER TUESDAY
INTO TUESDAY NIGHT...BUT THAT SHOULD BE GONE BY THE BUSY WEDNESDAY
TRAVEL DAY WITH HIGH PRESSURE BUILDING OVR UPR LAKES REGION.
SEEMS LIKE NICE WARMUP COULD OCCUR ON THANKSGIVING ONCE THE HIGH
MOVES EAST LEADING TO RETURN SW FLOW AT SFC. GFS SOUNDINGS SHOW
LOWER INVERSION BUT EVEN LIMITED MIXING YIELDS HIGHS WELL INTO THE
40S. GIVEN THE SW WINDS...INCREASED TEMPS FOR DOWNSLOPE AREAS NEAR
LK SUPERIOR TOWARD 50 DEGREES...CLOSER TO BIAS CORRECTED CONSENSUS.
LOOKS LIKE VERY NICE WEATHER FOR THE THANKSGIVING HOLIDAY...AND
LIKELY INTO FRIDAY TOO AS SW WINDS CONTINUE TO PUSH WARM AIR INTO
THE UPR LAKES AHEAD OF DEVELOPING TROUGH OVR THE PLAINS. RECORD
HIGHS FOR 24-25 NOVEMBER ARE MAINLY IN THE MID TO UPR 50S ACROSS THE
CWA.
&&
.AVIATION /FOR THE 12Z TAF ISSUANCE/...
EXTENSIVE BKN MID CLOUDS SPREAD OVER UPR MICHIGAN INTO THIS EVENING.
WARM FRONT ALOFT MAY TRIGGER FLURRIES AT KCMX THIS MORNING. EVEN
SO...VFR CONDITIONS ARE EXPECTED THROUGH THIS EVENING AT ALL SITES.
BY LATE TONIGHT...PASSAGE OF WEAK LOW PRESSURE TROUGH MAY RESULT IN
CIGS BECOMING MVFR AT KIWD AND KCMX.
HEADS UP THAT AFTER FAIRLY BENIGN CONDITIONS THROUGH TONIGHT AND
SATURDAY MORNING...WIDESPREAD IFR/LIFR CONDITIONS ARE EXPECTED
BEGINNING SATURDAY AFTN AT ALL THREE TAF SITES AS LOW PRESSURE
SYSTEM WITH WIDESPREAD/STEADY WET SNOW WORKS ACROSS MOST OF UPPER
MICHIGAN. CONDITIONS WILL NOT IMPROVE UNTIL SUNDAY MORNING AS THE
LOW MOVES AWAY FROM THE AREA. &&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
WEST-TO-EAST ORIENTED SFC TROUGH PASSES ACROSS LK SUPERIOR TODAY
LEADING TO DEVELOPING SE WINDS OVR WESTERN LK AND GUSTY SOUTHERLY
WINDS TO 30 KTS OVER EASTERN SECTIONS. WINDS DIMINISH TONIGHT...THEN
INCREASE BY LATE SATURDAY WITH ARRIVAL OF LOW PRESSURE SYSTEM FM THE
SOUTHERN PLAINS. SFC LOW NOT FCST TO DEEPEN SIGNIFICANTLY BUT THERE
IS DECENT COLD AIR RUSHING IN FM THE NORTH IN WAKE OF THE SYSTEM.
CANNOT RULE OUT LOW END NORTHERLY GALES SATURDAY NIGHT OVER CNTRL LK
SUPERIOR. NOT NEAR ENOUGH CONFIDENCE TO ISSUE GALE WATCH AT THIS
POINT THOUGH. SHOULD BE A WIDESPREAD SNOW OVER MOST OF LK SUPERIOR
AS THE LOW MOVES THROUGH THE AREA. LOW THEN QUICKLY SLIDES EAST
SUNDAY AND WINDS DIMINISH BY SUNDAY AFTN. WINDS SHOULD STAY LESS
THAN 25 KTS EARLY NEXT WEEK AS A WEAK TROUGH MOVES ACROSS FOLLOWED
BY A LARGE AREA OF HIGH PRESSURE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
DISCUSSION...JLB
EXTENDED...JLA
AVIATION...JLA
MARINE...JLA
CORRECTED EXTENDED FORECAST DISCUSSION
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS
THE CONUS. SEVERAL WEAK SHORTWAVES WERE EMBEDDED IN THE WRLY FLOW
OVER THE NRN PLAINS AND ADJOINING PORTIONS OF SRN CANADA. A STRONGER
UPPER LEVEL JET AND SHORTWAVE TROUGH THAT WILL IMPACT WEATHER
SATURDAY WAS MOVING INTO THE PAC NW. RADAR RETURNS OVER NRN WI AND
SW UPPER MI WERE INCREASING AS WAA AND ISENTROPIC ASCENT INCREASED
AHEAD OF A SFC TROUGH OVER THE PLAINS. SFC OBS INDICATED THAT THE
PCPN WAS MAINLY ALOFT.
&&
.DISCUSSION...
TODAY AND TONIGHT...THE NAM/GFS SHOW A BAND OF 285-295K ISENTROPIC
LIFT MOVING ACROSS UPPER MI. HOWEVER...THE NAM DEPICTION OF
SLOWER/LESS SATURATION IN THE LOWER LEVELS (BELOW 850 MB) LOOKS MORE
REALISTIC GIVEN UPSTREAM OBS/SOUNDINGS. SO...EXPECT ANY PCPN WILL
BE MORE LIGHT/PATCHY AND ONLY SLIGHT CHANCE TO CHANCE POPS WERE
INCLUDED. AS ANOTHER WEAK SHORTWAVE AND ASSOCIATED AREA OF 700-600 MB
FGEN MOVES INTO WRN LAKE SUPERIOR AND WRN UPPER MI LATE TODAY AND
THIS EVENING...SOME PATCHY LIGHT SNOW OR FLURRIES MAY ALSO PERSIST
INTO THE FAR WEST.
SATURDAY AND SATURDAY NIGHT...A FAST MOVING WAVE IS EXPECTED TO MOVE
FROM THE CENTRAL PLAINS SATURDAY MORNING TO NEAR THE STRAITS BY LATE
SATURDAY EVENING. THE GFS/NAM/ECMWF WERE IN REASONABLE AGREEMENT
WITH THE TRACK OF THE SFC LOW. HOWEVER...SINCE THERE HAS
BEEN SIGNIFICANT VARIATION WITH THE POSITION/STRENGTH OF THE
STRONGEST 800-600 MB FGEN AND THE STRUCTURE/PLACEMENT OF THE COUPLED
UPPER LEVEL JET...CONFIDENCE IN WHERE ANY HEAVY BANDS OF SNOW WILL
SET UP IS LIMITED. MODELS CONSENSUS STILL SUGGESTS THE STRONGER
DYNAMICS WILL AFFECT THE WEST HALF OF UPPER MI. SYNOPTIC QPF AMOUNTS
OF 0.25 TO 0.50 INCH STILL SEEM REASONABLE GIVEN 4 G/KG MOISTURE
AVBL AND THE PERIOD OF STRONG FORCING. SNOW/WATER RATIO VALUES ARE
LIKELY TO REMAIN NEAR OR EVEN BELOW 10/1 WITH THE STRONGER UPWARD
MOTION BELOW THE -12C TO -15C LAYER. ADDITIONAL UPSLOPE AND LAKE
ENHANCEMENT IS EXPECTED NEAR IWD AND OVER N CNTRL UPPER MI.
HOWEVER...THE WINDOW FOR HEAVIER SNOW DURING THE PERIOD OF SYNOPTIC
FORCING IS RELATIVELY SHORT. GIVEN THE AMOUNT OF UNCERTAINTY AND WITH
OVERALL SNOWFALL AMOUNTS EXPECTED TO REMAIN MAINLY IN THE 3 TO 7
INCH RANGE BTWN 18Z SAT AND 12Z SUN AN SPS RATHER THAN A WATCH WAS
ISSUED. A NAM/GFS BLEND OF LOW LEVEL THICKNESS/WET BULB ZERO HEIGHTS
WERE USED FOR PLACEMENT OF THE RAIN SNOW LINE FROM ABOUT KP53 TO JUST
SE OF KIMT.
SUNDAY....N TO NNW WINDS 850 MB TEMP TO AROUND -11C SHOULD KEEP SOME
SCT -SHSN GOING IN THE MORNING. AS THE SFC RIDGE BUILDS INTO THE
AREA IN THE AFTERNOON ALONG WITH DRIER AIR AND LOWER INVERSION
HEIGHTS...ANY REMAINING LES WILL TAPER OFF.
FOR THE EXTENDED...SFC TROUGH SLIDES ACROSS MAINLY LK SUPERIOR ON
MONDAY LEADING TO WARM AIR ADVECTION ALOFT AND SOME ISENTROPIC LIFT.
GFS/CANADIAN FAVOR A PERIOD OF LGT SNOW MONDAY BUT FOR MOST PART THE
ECMWF REMAINS DRY. GFS FCST SOUNDINGS SHOW DEEP MOISTURE AND LIFT
ACTING UPON FAVORABLE TEMPS FOR SNOW INITIATION...SO AT LEAST THE
GFS QPF IS CONSISTENT WITH ITS OTHER MODEL FIELDS. SHORTWAVE IS FCST
TO TRACK MAINLY ACROSS LK SUPERIOR AND WOULD EXPECT GREATEST CHANCE
OF SATURATION/PCPN TO OCCUR THERE AS WELL. ONLY HAVE CHANCE POPS ON
THE KEWEENAW. EVEN IF GFS IS CORRECT...WOULD ONLY SEE SUB ADVY SNOW
AMOUNTS...AND THAT IS PRETTY GENEROUS. AFTER TROUGH EXITS...LOOKS
LIKE A QUIET PERIOD OF WEATHER OVR UPR LAKES LEADING INTO THE
THANKSGIVING HOLIDAY AS WRLY FLOW KEEPS MAIN STORM TRACK SUPPRESSED
TO SOUTH. MAY BE A SYSTEM THAT AFFECTS LOWER MICHIGAN LATER TUESDAY
INTO TUESDAY NIGHT...BUT THAT SHOULD BE GONE BY THE BUSY WEDNESDAY
TRAVEL DAY WITH HIGH PRESSURE BUILDING OVR UPR LAKES REGION.
SEEMS LIKE NICE WARMUP COULD OCCUR ON THANKSGIVING ONCE THE HIGH
MOVES EAST LEADING TO RETURN SW FLOW AT SFC. GFS SOUNDINGS SHOW
LOWER INVERSION BUT EVEN LIMITED MIXING YIELDS HIGHS WELL INTO THE
40S. GIVEN THE SW WINDS...INCREASED TEMPS FOR DOWNSLOPE AREAS NEAR
LK SUPERIOR TOWARD 50 DEGREES...CLOSER TO BIAS CORRECTED CONSENSUS.
LOOKS LIKE VERY NICE WEATHER FOR THE THANKSGIVING HOLIDAY...AND
LIKELY INTO FRIDAY TOO AS SW WINDS CONTINUE TO PUSH WARM AIR INTO
THE UPR LAKES AHEAD OF DEVELOPING TROUGH OVR THE PLAINS. RECORD
HIGHS FOR 24-25 NOVEMBER ARE MAINLY IN THE MID TO UPR 50S ACROSS THE
CWA.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
AS WINDS BECOME MORE SOUTHERLY WITH TIME...THE LAKE EFFECT SNOW
SHOWERS AND BANDS WILL PUSH OFFSHORE FROM KCMX OVERNIGHT AND MVFR
CIGS OR VIS IN THE SNOWBANDS WILL IMPROVE TO VFR AND THIS SHOULD
LAST THROUGH THE REST OF THE PERIOD.
VFR CONDITIONS AT BOTH KIWD AND KSAW THROUGH THE PERIOD. AS WINDS
DECOUPLE LATE TONIGHT...PUT IN SOME LLWS AT KIWD THAT WILL LAST INTO
FRIDAY MID MORNING. WINDS WILL GET GUSTY AT KSAW FRIDAY.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
WEST-TO-EAST ORIENTED SFC TROUGH PASSES ACROSS LK SUPERIOR TODAY
LEADING TO DEVELOPING SE WINDS OVR WESTERN LK AND GUSTY SOUTHERLY
WINDS TO 30 KTS OVER EASTERN SECTIONS. WINDS DIMINISH TONIGHT...THEN
INCREASE BY LATE SATURDAY WITH ARRIVAL OF LOW PRESSURE SYSTEM FM THE
SOUTHERN PLAINS. SFC LOW NOT FCST TO DEEPEN SIGNIFICANTLY BUT THERE
IS DECENT COLD AIR RUSHING IN FM THE NORTH IN WAKE OF THE SYSTEM.
CANNOT RULE OUT LOW END NORTHERLY GALES SATURDAY NIGHT OVER CNTRL LK
SUPERIOR. NOT NEAR ENOUGH CONFIDENCE TO ISSUE GALE WATCH AT THIS
POINT THOUGH. SHOULD BE A WIDESPREAD SNOW OVER MOST OF LK SUPERIOR
AS THE LOW MOVES THROUGH THE AREA. LOW THEN QUICKLY SLIDES EAST
SUNDAY AND WINDS DIMINISH BY SUNDAY AFTN. WINDS SHOULD STAY LESS
THAN 25 KTS EARLY NEXT WEEK AS A WEAK TROUGH MOVES ACROSS FOLLOWED
BY A LARGE AREA OF HIGH PRESSURE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
DISCUSSION...JLB
EXTENDED...JLA
AVIATION...JLA
MARINE...JLA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
559 AM EST FRI NOV 18 2011
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL PATTERN ACROSS
THE CONUS. SEVERAL WEAK SHORTWAVES WERE EMBEDDED IN THE WRLY FLOW
OVER THE NRN PLAINS AND ADJOINING PORTIONS OF SRN CANADA. A STRONGER
UPPER LEVEL JET AND SHORTWAVE TROUGH THAT WILL IMPACT WEATHER
SATURDAY WAS MOVING INTO THE PAC NW. RADAR RETURNS OVER NRN WI AND
SW UPPER MI WERE INCREASING AS WAA AND ISENTROPIC ASCENT INCREASED
AHEAD OF A SFC TROUGH OVER THE PLAINS. SFC OBS INDICATED THAT THE
PCPN WAS MAINLY ALOFT.
&&
.DISCUSSION...
TODAY AND TONIGHT...THE NAM/GFS SHOW A BAND OF 285-295K ISENTROPIC
LIFT MOVING ACROSS UPPER MI. HOWEVER...THE NAM DEPICTION OF
SLOWER/LESS SATURATION IN THE LOWER LEVELS (BELOW 850 MB) LOOKS MORE
REALISTIC GIVEN UPSTREAM OBS/SOUNDINGS. SO...EXPECT ANY PCPN WILL
BE MORE LIGHT/PATCHY AND ONLY SLIGHT CHANCE TO CHANCE POPS WERE
INCLUDED. AS ANOTHER WEAK SHORTWAVE AND ASSOCIATED AREA OF 700-600 MB
FGEN MOVES INTO WRN LAKE SUPERIOR AND WRN UPPER MI LATE TODAY AND
THIS EVENING...SOME PATCHY LIGHT SNOW OR FLURRIES MAY ALSO PERSIST
INTO THE FAR WEST.
SATURDAY AND SATURDAY NIGHT...A FAST MOVING WAVE IS EXPECTED TO MOVE
FROM THE CENTRAL PLAINS SATURDAY MORNING TO NEAR THE STRAITS BY LATE
SATURDAY EVENING. THE GFS/NAM/ECMWF WERE IN REASONABLE AGREEMENT
WITH THE TRACK OF THE SFC LOW. HOWEVER...SINCE THERE HAS
BEEN SIGNIFICANT VARIATION WITH THE POSITION/STRENGTH OF THE
STRONGEST 800-600 MB FGEN AND THE STRUCTURE/PLACEMENT OF THE COUPLED
UPPER LEVEL JET...CONFIDENCE IN WHERE ANY HEAVY BANDS OF SNOW WILL
SET UP IS LIMITED. MODELS CONSENSUS STILL SUGGESTS THE STRONGER
DYNAMICS WILL AFFECT THE WEST HALF OF UPPER MI. SYNOPTIC QPF AMOUNTS
OF 0.25 TO 0.50 INCH STILL SEEM REASONABLE GIVEN 4 G/KG MOISTURE
AVBL AND THE PERIOD OF STRONG FORCING. SNOW/WATER RATIO VALUES ARE
LIKELY TO REMAIN NEAR OR EVEN BELOW 10/1 WITH THE STRONGER UPWARD
MOTION BELOW THE -12C TO -15C LAYER. ADDITIONAL UPSLOPE AND LAKE
ENHANCEMENT IS EXPECTED NEAR IWD AND OVER N CNTRL UPPER MI.
HOWEVER...THE WINDOW FOR HEAVIER SNOW DURING THE PERIOD OF SYNOPTIC
FORCING IS RELATIVELY SHORT. GIVEN THE AMOUNT OF UNCERTAINTY AND WITH
OVERALL SNOWFALL AMOUNTS EXPECTED TO REMAIN MAINLY IN THE 3 TO 7
INCH RANGE BTWN 18Z SAT AND 12Z SUN AN SPS RATHER THAN A WATCH WAS
ISSUED. A NAM/GFS BLEND OF LOW LEVEL THICKNESS/WET BULB ZERO HEIGHTS
WERE USED FOR PLACEMENT OF THE RAIN SNOW LINE FROM ABOUT KP53 TO JUST
SE OF KIMT.
SUNDAY....N TO NNW WINDS 850 MB TEMP TO AROUND -11C SHOULD KEEP SOME
SCT -SHSN GOING IN THE MORNING. AS THE SFC RIDGE BUILDS INTO THE
AREA IN THE AFTERNOON ALONG WITH DRIER AIR AND LOWER INVERSION
HEIGHTS...ANY REMAINING LES WILL TAPER OFF.
FOR THE EXTENDED...PRETTY GOOD AGREEMENT FM GFS/ECMWF/CANADIAN THAT
UPR LEVELS SHOW INCREASING TROFFINESS BY LATE WEEKEND. MODELS HAVE
LATCHED ONTO A STRONGER SHORTWAVE DROPPING THROUGH SUNDAY INTO
SUNDAY NIGHT ALONG WITH A SFC LOW SLIDING ACROSS UPR LAKES. SLIGHT
DIFFERENCES WITH TRACK OF SFC LOW...BUT ALL GUIDANCE INDICATES WARM
AIR ADVECTION AHEAD OF TROUGH AND DIVERGENCE ALOFT FM JET DIGGING IN
ON BACK SIDE OF TROUGH INTO UPR MISSISSIPPI RIVER VALLEY WILL SUPPORT
SOME SHRA WORKING THROUGH UPR MI SUNDAY AND SUNDAY NIGHT. MODEL
CONSENSUS POINTED TO CHANCE POPS OVR WEST HALF OF CWA ON SUNDAY THEN
MOVING INTO EASTERN CWA SUNDAY NIGHT. ABOVE AVERAGE CONFIDENCE IN
TIMING/EXTENT OF RAIN CHANCES THROUGH SUNDAY. RIDGE WORKS ACROSS FOR
MONDAY WITH MAINLY DRY WX FIGURED.
BEYOND MONDAY...ANOTHER TROUGH IS FCST TO COME ACROSS UPR LAKES IN
FLATTENING UPR FLOW. THE FLOW BECOMING MORE ZONAL IS LEADING TO
TIMING DIFFERENCES IN THE MODELS. GFS IS QUICKEST WITH NEXT SFC
TROUGH...PUSHING IT COMPLETELY THROUGH AREA BY WEDNESDAY MORNING.
LATEST ECMWF/CANADIAN ARE MUCH SLOWER AND MORE AMPLIFIED...WITH A
STRONG SFC LOW FCST TO MEANDER OVR UPR LAKES THROUGH AT LEAST
WEDNESDAY. GFS HAS BETTER RUN-TO-RUN CONSISTENCY AND MATCHED
CONTINUITY SO DID SIDE WITH THAT IDEA FOR NOW. TOUGH TO BET AGAINST
ECMWF IN THE EXTENDED PERIODS THOUGH...SO HAVE LOWER CONFIDENCE IN
EXTENDED BEYOND MONDAY DUE TO THE TIMING DIFFERENCES IN MODELS. WHAT
IS AGREED UPON BY MODELS IS COOL DOWN BEHIND THIS SYSTEM MID-LATE
WEEK WITH POSSIBLE RAIN/SNOW SHOWERS. THE MAIN QUESTION IS JUST HOW
QUICK THIS WILL OCCUR.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
AS WINDS BECOME MORE SOUTHERLY WITH TIME...THE LAKE EFFECT SNOW
SHOWERS AND BANDS WILL PUSH OFFSHORE FROM KCMX OVERNIGHT AND MVFR
CIGS OR VIS IN THE SNOWBANDS WILL IMPROVE TO VFR AND THIS SHOULD
LAST THROUGH THE REST OF THE PERIOD.
VFR CONDITIONS AT BOTH KIWD AND KSAW THROUGH THE PERIOD. AS WINDS
DECOUPLE LATE TONIGHT...PUT IN SOME LLWS AT KIWD THAT WILL LAST INTO
FRIDAY MID MORNING. WINDS WILL GET GUSTY AT KSAW FRIDAY.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
WEST-TO-EAST ORIENTED SFC TROUGH PASSES ACROSS LK SUPERIOR TODAY
LEADING TO DEVELOPING SE WINDS OVR WESTERN LK AND GUSTY SOUTHERLY
WINDS TO 30 KTS OVER EASTERN SECTIONS. WINDS DIMINISH TONIGHT...THEN
INCREASE BY LATE SATURDAY WITH ARRIVAL OF LOW PRESSURE SYSTEM FM THE
SOUTHERN PLAINS. SFC LOW NOT FCST TO DEEPEN SIGNIFICANTLY BUT THERE
IS DECENT COLD AIR RUSHING IN FM THE NORTH IN WAKE OF THE SYSTEM.
CANNOT RULE OUT LOW END NORTHERLY GALES SATURDAY NIGHT OVER CNTRL LK
SUPERIOR. NOT NEAR ENOUGH CONFIDENCE TO ISSUE GALE WATCH AT THIS
POINT THOUGH. SHOULD BE A WIDESPREAD SNOW OVER MOST OF LK SUPERIOR
AS THE LOW MOVES THROUGH THE AREA. LOW THEN QUICKLY SLIDES EAST
SUNDAY AND WINDS DIMINISH BY SUNDAY AFTN. WINDS SHOULD STAY LESS
THAN 25 KTS EARLY NEXT WEEK AS A WEAK TROUGH MOVES ACROSS FOLLOWED
BY A LARGE AREA OF HIGH PRESSURE.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
DISCUSSION...JLB
EXTENDED...JLA
AVIATION...JLA
MARINE...JLA
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1150 PM EST THU NOV 17 2011
LATEST UPDATE...AVIATION...
.SYNOPSIS...(315 PM EST THU NOV 17 2011)
THE LAKE EFFECT SNOW SHOWERS WILL GRADUALLY DIMINISH THIS EVENING.
HIGH PRESSURE OVER THE MIDDLE MISSISSIPPI VALLEY WILL STRENGTHEN AS
IT BUILDS EAST INTO THE CENTRAL APPALACHIANS ON FRIDAY. A GUSTY
SOUTHWESTERLY FLOW WILL SETUP HERE IN LOWER MICHIGAN DURING THE DAY
AND PERSIST INTO SATURDAY. A COLD FRONT WILL SLIP SOUTHEASTWARD
THROUGH THE REGION SATURDAY NIGHT PRODUCING SOME RAIN SHOWERS.
COOLER AIR WILL THEN FILTER IN FOR THE REMAINDER OF THE WEEKEND.
&&
.SHORT TERM...(315 PM EST THU NOV 17 2011)
(TONIGHT THROUGH SATURDAY NIGHT)...
THE MAIN CHALLENGE IN THE SHORT TERM DEALS WITH THE WIND GUSTS ON
FRIDAY.
BUFKIT OVERVIEWS SHOW MIXING HEIGHTS TAPPING INTO THE 40
KNOT WIND RANGE ALONG THE LAKESHORE DURING THE DAY ON FRIDAY. ALSO
FSL RUC DATA SUGGESTS WINDS OVER 40 KNOTS MOVING INLAND DURING THE
DAY. PROFILER DATA FROM THE LOWER PLAINS SHOWS THE LOW
LEVEL JET FORMING AND IT IS ALREADY ABOUT 10 KNOTS STRONGER THAN
FORECASTED. WILL ISSUE A WIND ADVISORY FOR FRIDAY FROM 12Z TO 00Z.
MIXING HEIGHTS LOWER DURING THE EVENING AND THAT SHOULD ALLOW FOR
THE WIND TO DECREASE.
THE TIMING OF THE SHOWERS LATER SATURDAY INTO SATURDAY LOOKS GOOD.
I DID DELAY THE SHOWERS SLIGHTLY GIVEN THE SOMEWHAT SLOWER TREND OF
THE FRONTAL PASSAGE. AS A RESULT I TOOK OUT THE MENTION OF SHOWERS
PRIOR TO 18Z SAT.
A DECENT WARMUP IS IN STORE FOR THE REGION ON SATURDAY. LOW LEVEL
THERMAL PROFILES SUPPORT HIGHS TOPPING 50 DEGREES.
&&
.LONG TERM...(315 PM EST THU NOV 17 2011)
(SUNDAY THROUGH THANKSGIVING DAY)
THE LONG TERM PORTION OF THE FCST LOOKS RATHER TRANQUIL...ESPECIALLY
BY MID-LATE NOVEMBER STANDARDS FOR MICHIGAN. WE WILL HAVE TO WATCH A
POSSIBLE SYSTEM THAT COULD STILL IMPACT AT LEAST A PORTION OF THE
AREA TUE INTO TUE NIGHT.
FRONTAL SYSTEM MOVING THROUGH SAT/SAT NIGHT STILL APPEARS TO JUST
CLEAR THE CWFA BY 12Z SUN. DRY NE FLOW AROUND THE INCOMING SFC RIDGE
AND NOT SO COLD TEMPS /H850 TEMPS 0 TO -2C/ WILL BRING QUIET AND
SEASONABLE TEMPS TO THE AREA. WE ARE EXPECTING THIS HIGH TO RULE
ACROSS THE AREA AT LEAST THROUGH MON. FOR NOW...WE ARE DISCOUNTING
THE 12Z GFS BRINGING LIGHT PCPN TO THE AREA. IT SEEMS TO BE TRYING
TO PHASE SRN STREAM MOISTURE WITH A WEAK NRN STREAM TROUGH. THE
SETUP LOOKS OVERDONE WITH MOISTURE THIS FAR NORTH AND NOT FAVORABLE
FOR PCPN ON MON FOR NOW.
THE TRENDS IN THE MODELS ARE TO HAVE THE SYSTEM FOR TUE/WED A LITTLE
FURTHER NORTH THAN WAS EXPECTED 24 HOURS AGO. WE CAN NOT DISCOUNT
THIS IDEA EXPECTING IT MAY BE A LITTLE STRONGER THAN WHAT IS BEING
SAMPLED NOW. HOWEVER UNLESS THERE IS GOOD PHASING BETWEEN THE TWO
STREAMS...IT SHOULD CONTINUE TO MAINLY MISS THE AREA. THE 00Z EURO
WAS QUITE THE OUTLIER WITH A CLOSED NRN STREAM LOW PHASING WITH THE
SRN STREAM...AND BRINGING A LOT OF PCPN TO THE AREA TUE/WED. THE NEW
EURO HAS BACKED AWAY FROM THAT THINKING...AND IS CLOSER TO THE
ENSEMBLES. IN COORDINATION WITH SURROUNDING OFFICES...WE HAVE ADDED
A SMALL CHC OF PCPN TUE AND TUE NIGHT DOWN SOUTH FOR NOW...AND WILL
CONTINUE TO MONITOR THE TRENDS.
ALL OF THE MODELS HAVE A FAIRLY GOOD RIDGE THEN BUILDING OVER THE
AREA FOR WED AND THANKSGIVING DAY AS ANOTHER STRONG TROUGH TAKES
SHAPE ALONG THE WEST COAST. THIS SHOULD ALLOW FOR MORE SEASONABLE TO
SLIGHTLY ABOVE AVERAGE TEMPS FOR NOVEMBER ALONG WITH DRY CONDITIONS
FOR THE FIRST PART OF THE HOLIDAY TRAVEL PERIOD FOR MICHIGAN.
&&
.AVIATION...(1150 PM EST THU NOV 17 2011)
VFR CONDITIONS THROUGH FRIDAY EVENING...BUT STRONG WINDS WILL AFFECT
AVIATION. WINDS WILL GO SOUTHWEST THEN SOUTH ON FRIDAY MORNING AND
INCREASE TO NEAR 20 KNOTS WITH GUSTS OVER 30 KNOTS BY 18Z FRIDAY.
SOME GUSTS TO 40 KNOTS ARE POSSIBLE. THESE STRONG WINDS WILL
CONTINUE INTO FRIDAY EVENING THEN DIMINISH OVERNIGHT.
&&
.MARINE...(315 PM EST THU NOV 17 2011)
THE ARRIVAL OF A LOW LEVEL JET COUPLED WITH INCREASED MIXING ON
FRIDAY SUPPORTS KEEPING THE GALE WARNING FOR FRIDAY. MIXING
HEIGHTS SUGGEST THE NEARSHORE ZONES WILL REACH INTO THE 40 KNOT
RANGE OF WINDS FRIDAY. THE LOW LEVEL JET AND INCREASED MIXING
PERSISTS THROUGH 00Z SAT...THUS I WILL KEEP THE WARNING GOING
THROUGH MUCH OF THE NIGHT.
&&
.HYDROLOGY...(315 PM EST WED NOV 16 2011)
ANY QPF THROUGH THE PERIOD IS FORECASTED TO BE RELATIVELY LIGHT. AS
A RESULT... NO HYDRO ISSUES ANTICIPATED.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WIND ADVISORY FOR THE LAKESHORE COUNTIES FRIDAY.
LM...SMALL CRAFT ADVISORY ALL NEARSHORE ZONES THROUGH TONIGHT.
GALE WARNING FRIDAY INTO FRIDAY NIGHT ALL NEARSHORE ZONES.
&&
$$
SYNOPSIS: MJS
SHORT TERM: MJS
LONG TERM: NJJ
AVIATION: OSTUNO
MARINE: MJS
HYDROLOGY: MJS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
348 AM EST FRI NOV 18 2011
.SYNOPSIS...
A CHILLY AIRMASS WILL REMAIN IN PLACE TODAY WITH LAKE EFFECT SNOW
EAST OF THE LAKES GRADUALLY ENDING. OUTSIDE OF LAKE EFFECT IT WILL
BE PARTLY SUNNY AND BREEZY. DRY CONDITIONS WILL LAST INTO SATURDAY
WITH HIGH PRESSURE NEARBY OVER THE EASTERN SEABOARD. A SOUTHWEST
FLOW OF WARMER AIR WILL BRING A QUICK REBOUND IN TEMPERATURES AS
THEY RECOVER TO A LITTLE ABOVE AVERAGE FOR THE WEEKEND. A COLD FRONT
WILL BRING A CHANCE OF A FEW LIGHT SHOWERS ON SUNDAY AND WILL USHER
IN COOLER AND SEASONABLE TEMPERATURES FOR THE START OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
MAIN CONCERN THROUGH THIS MORNING CONTINUES TO REVOLVE AROUND LAKE
EFFECT.
OFF LAKE ERIE...JUST A LARGE AREA OF VERY LIGHT FLURRIES REMAINS
EARLY THIS MORNING ACROSS MUCH OF THE WESTERN SOUTHERN TIER. LATEST
HIGH RESOLUTION HRRR MODEL RUN SUGGESTS WE MAY SEE A VERY MODEST
INCREASE IN SNOW SHOWERS FROM 12Z-15Z ACROSS THE SOUTHERN TIER AND
PORTIONS OF SOUTHERN ERIE AND WYOMING COUNTIES. THIS APPEARS TO HAVE
SOME VALIDITY WITH IR SATELLITE STILL SHOWING PLENTY OF LAKE EFFECT
CLOUDS ALL THE WAY WEST TO CLEVELAND...AND WITH BOUNDARY LAYER FLOW
BACKING TO THE WSW THIS MORNING FETCH WILL INCREASE. STILL...EXPECT
NOTHING MORE THAN FLURRIES AND SCATTERED SNOW SHOWERS WITH ANY
ADDITIONAL ACCUMULATION LESS THAN AN INCH. THIS ACTIVITY SHOULD END
COMPLETELY BY LATE MORNING AS INVERSION HEIGHTS CRASH AND DRY AIR
BECOMES TOO DIFFICULT TO OVERCOME.
OFF LAKE ONTARIO...AN IMPRESSIVE PLUME AT 0830Z EXTENDS INTO MUCH OF
OSWEGO COUNTY WITH THE BEST ORGANIZATION WE HAVE SEEN ALL NIGHT. IR
SATELLITE TELLS THE STORY WITH THIS BURST OF INTENSITY CORRESPONDING
TO THE PASSAGE OF A BLOB OF DEEPER MOISTURE WITH ROOTS ACROSS THE
UPPER GREAT LAKES. IR SATELLITE IMAGERY CONTINUES TO SHOW AN
UPSTREAM CONNECTION TO GEORGIAN BAY...AND THIS SHOULD PRODUCE SOME
NICE SNOWFALL RATES ACROSS OSWEGO COUNTY THROUGH EARLY TO MID
MORNING WITH OCCASIONAL 1-2 INCH PER HOUR BURSTS. BY DAYBREAK EXPECT
THE MAIN FOCUS OF THIS BAND TO BE ACROSS THE NORTHERN HALF OF OSWEGO
COUNTY EXTENDING INTO THE SOUTHWEST CORNER OF LEWIS COUNTY NEAR
OSCEOLA. THIS LAST GASP HOLDS PROMISE TO GET SNOWFALL AMOUNTS UP TO
WARNING CRITERIA...WITH ANOTHER 2-4 INCHES THROUGH LATE MORNING
BRINGING STORM TOTALS TO 6-9 INCHES IN THE MOST PERSISTENT BANDS.
BY MID TO LATE MORNING THE BOUNDARY LAYER FLOW WILL BEGIN TO BACK
MORE WSW...WHICH WILL CARRY THE LAKE BAND NORTH ACROSS THE TUG HILL
AND SOUTHERN JEFFERSON COUNTY. AT THE SAME TIME...INVERSION HEIGHTS
WILL BE COMING DOWN AND MOISTURE DECREASING...SO EXPECT A RAPID
WEAKENING TREND AFTER ABOUT 15Z. THE BAND SHOULD DISSIPATE
ALTOGETHER BY EARLY AFTERNOON AS THE CRASHING INVERSION AND
DECREASING MOISTURE BECOME TOO MUCH TO OVERCOME.
OTHERWISE AREAS OUTSIDE OF LAKE EFFECT WILL SEE PLENTY OF SUNSHINE
TODAY...AND EVEN LAKE EFFECT AREAS SHOULD SEE SOME SUNSHINE THIS
AFTERNOON AFTER THE LAKE CLOUDS BEGIN TO DISSIPATE. STEADY WARM AIR
ADVECTION WILL BEGIN...BUT WILL BE TOO LATE TO BOOST TEMPS MUCH WITH
THE LOWER ELEVATIONS REACHING THE LOWER 40S WITH MID TO UPPER 30S
ACROSS HIGHER TERRAIN. A BRISK WIND WILL KEEP A WIND CHILL IN THE
AIR AS WELL.
TONIGHT HIGH PRESSURE WILL BUILD ACROSS THE MID ATLANTIC STATES. THE
SOUTHWEST RETURN FLOW WILL INCREASE ACROSS THE LOWER LAKES ON THE
WESTERN PERIPHERY OF THIS HIGH...WITH STEADY WARM AIR ADVECTION. ON
THE LAKE PLAINS BOUNDARY LAYER WINDS WILL REMAIN MIXED...WHICH WILL
ALLOW FOR STEADY OR SLOWLY RISING TEMPS AFTER EVENING LOWS IN THE
30S. SOME OF THE MORE SHELTERED INLAND VALLEYS WILL STILL BE ABLE TO
PARTIALLY DECOUPLE AND DROP OFF INTO THE 20S ONCE AGAIN. EXPECT A
FEW PERIODS OF MID/HIGH CLOUD COVER WITH MOST AREAS PARTLY CLOUDY
OVERNIGHT...EXCEPT FOR THE NORTH COUNTRY WHERE THICKER MID LEVEL
CLOUD ALONG THE RETREATING WARM FRONT MAY END UP PRODUCING A MOSTLY
CLOUDY NIGHT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
HIGH PRESSURE CENTERED OFF THE ATLANTIC COAST WILL BRING DRY WEATHER
ON SATURDAY. WARM AIR ADVECTION ASSOCIATED WITH A POTENT LOW LEVEL
JET WILL BRING AN INCREASE IN MID LEVEL CLOUDS DURING THE
AFTERNOON...ESPECIALLY FOR AREAS NEAR LAKE ONTARIO. BUT...RELATIVELY
DRY AIR IN THE LOWER LEVELS SHOULD PRECLUDE THE DEVELOPMENT OF ANY
RAIN SHOWERS. AFTERNOON TEMPERATURES WILL HOVER AROUND 50...BUT A
MODEST SOUTHERLY FLOW WILL PUT A CHILL IN THE AIR. THE LATEST BUFKIT
TEMPERATURE PROFILES SUGGESTS THAT THE PRESENCE OF A LOW LEVEL
INVERSION SHOULD PREVENT THE TRANSFER OF HIGHER WINDS ALOFT
(ASSOCIATED WITH THE LOW LEVEL JET) DOWN TO THE SURFACE.
LOW PRESSURE THAT WILL BE MOVING OUT OF THE CENTRAL PLAINS SATURDAY
AFTERNOON IS FORECAST TO LIFT NORTH OF THE CENTRAL GREAT LAKES
SATURDAY NIGHT...THEN TRACK ACROSS SOUTHERN QUEBEC SUNDAY. ANOTHER
LOW LEVEL JET ADVANCING AHEAD OF THE SURFACE LOW WILL ADVECT
INCREASING LOW LEVEL MOISTURE ACROSS THE CWA SATURDAY NIGHT. THIS
WILL ALLOW SCATTERED RAIN SHOWERS TO SPREAD EAST ACROSS THE AREA
OVERNIGHT. A COLD FRONT TRAILING SOUTH OF THE SURFACE LOW WILL CROSS
WESTERN AND CENTRAL NEW YORK SUNDAY AFTERNOON. A FEW MORE RAIN
SHOWERS WILL ACCOMPANY THE FRONTAL PASSAGE...BUT AVAILABLE MOISTURE
WILL BE RATHER LIMITED...SO QPF SHOULD REMAIN UNDER A TENTH OF AN
INCH.
THE PROJECTED PATH OF THE LOW COULD RESULT IN RATHER WINDY
CONDITIONS ON SUNDAY...ESPECIALLY IF THE NAM`S TREND OF A
LOWER SURFACE PRESSURE VERIFIES. THE NAM AND GFS ALSO SHOWS FAIRLY
IMPRESSIVE ISALLOBARIC PRESSURE RISES SETTING UP JUST TO OUR
NORTHWEST DURING THE AFTERNOON AS COLDER AIR ADVECTS IN BEHIND THE
FRONT. BASED ON THESE TRENDS...WIND GUSTS MAY APPROACH ADVISORY
CRITERIA ON SUNDAY ACROSS THE NIAGARA FRONTIER AND LOWER GENESEE
VALLEY.
HIGH PRESSURE BUILDING IN BEHIND THE DEPARTED COLD FRONT WILL BRING
DRY CONDITIONS SUNDAY NIGHT ALONG WITH DIMINISHING WINDS. LAKE
EFFECT PCPN BEHIND THE FRONT IS NOT EXPECTED TO BE AN ISSUE AT THIS
TIME AS LOW LEVEL MOISTURE WILL BE LIMITED AND THERE WILL BE PLENTY
OF DIRECTIONAL SHEAR.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
UNCERTAINTY CREEPS INTO THE FORECAST BY MONDAY AS TIMING BETWEEN THE
MAJOR MODELS START TO FALL APART. GFS/GEM SWING A NORTHERN STREAM
SHORTWAVE ACROSS THE GREAT LAKES WHILE DEVELOPING A SURFACE TROUGH
ACROSS THE SOUTHERN PLAINS TO THE OHIO VALLEY. ECMWF HOLDS THE DOME
OF HIGH PRESSURE OVER THE REGION LONGER...ESSENTIALLY DEFLECTING THE
ABOVE MENTIONED SYSTEMS AROUND IT/S PERIPHERY AND AWAY FROM WESTERN
NEW YORK. THIS PHASE DIFFERENCE BETWEEN THE MODELS HOLDS INTO THE
MID WEEK MAKING ANY EXACT PREDICTIONS VERY DICEY. GIVEN THE LEVEL OF
UNCERTAINTY...WILL ELECT TO CONTINUE TRENDING TOWARDS THE GENERIC
HPC BLEND THAT KEEPS CHANCE POPS IN FOR MUCH OF THE WEEK NEXT WEEK
WHICH TEMPERATURES NEAR NORMAL FOR LATE NOVEMBER WITH HIGHS IN THE
40S AND LOWS IN THE LOW TO MID 30S ACROSS MOST LOCALES.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
LIGHT LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO BRING SPOTTY MVFR
CONDITIONS ACROSS THE WESTERN SOUTHERN TIER THROUGH MID MORNING.
EAST OF LAKE ONTARIO A MORE ORGANIZED BAND OF LAKE EFFECT SNOW
WILL BRING LOCAL IFR CONDITIONS IN AREAS BETWEEN KART AND KSYR
THROUGH LATE MORNING BEFORE DISSIPATING BY EARLY AFTERNOON.
OTHERWISE VFR CONDITIONS WILL PREVAIL.
OUTLOOK...
SATURDAY...MAINLY VFR.
SUNDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.
MONDAY...MAINLY VFR.
TUESDAY...MAINLY VFR WITH CHANCE OF SHOWERS.
&&
.MARINE...
A STRONG PRESSURE GRADIENT WILL REMAIN IN PLACE BETWEEN HIGH
PRESSURE OVER THE SOUTHEAST STATES AND SEVERAL WAVES OF LOW PRESSURE
OVER THE UPPER GREAT LAKES AND SOUTHEAST CANADA. THIS WILL KEEP HIGH
END SMALL CRAFT ADVISORY CONDITIONS GOING RIGHT THROUGH THE WEEKEND.
MODERATE TO STRONG WESTERLIES WILL CONTINUE TODAY AND GRADUALLY BACK
TO THE SOUTHWEST THEN SSW TONIGHT AND CONTINUE AT 20-30 KNOTS. THE
MODERATE TO STRONG SOUTHWEST WINDS WILL CONTINUE RIGHT THROUGH
SUNDAY BEFORE A COLD FRONT SHIFTS WINDS TO THE NORTHWEST SUNDAY
NIGHT. HIGH PRESSURE WILL BUILD OVER THE REGION MONDAY AND FINALLY
BRING AN END TO THE GUSTY WINDS.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WARNING UNTIL 11 AM EST THIS MORNING FOR
NYZ006.
LAKE EFFECT SNOW ADVISORY UNTIL 8 AM EST THIS MORNING FOR
NYZ005.
LAKE EFFECT SNOW ADVISORY UNTIL 11 AM EST THIS MORNING FOR
NYZ008.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST SUNDAY FOR LEZ020-040-041.
SMALL CRAFT ADVISORY UNTIL 6 PM EST SATURDAY FOR
LOZ042>045.
&&
$$
SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK
SHORT TERM...TJP
LONG TERM...TJP
AVIATION...HITCHCOCK
MARINE...HITCHCOCK
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1002 PM EST SAT NOV 19 2011
.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFFSHORE THIS WEEKEND AND INTO EARLY NEXT
WEEK. TEMPERATURES WILL BEGIN TO WARM OVER THE WEEKEND AS SOUTHERLY
WINDS DEVELOP. A COLD FRONT WILL MOVE THROUGH WEDNESDAY. COOLER
WEATHER IS EXPECTED LATE NEXT WEEK AS HIGH PRESSURE BUILDS IN.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 10 PM SATURDAY...LIGHT EASTERLY/ONSHORE FLOW HAS
DEVELOPED AS SURFACE RIDGE AXIS MOVES OFFSHORE...BRINGING
TEMPERATURES ALONG THE COAST UP A TAD...IN THE LOWER TO MID 60S
MANY LOCATIONS. WILL LOOK AT MODIFYING THE TEMPERATURE CURVE IF
NEED BE TO ACCOUNT FOR THIS. OTHERWISE...FORECAST REMAINS ON
TRACK. PREVIOUS DISCUSSIONS FOLLOW:
QUITE A DIFFERENCE FROM 24 HOURS AGO. RADIATIONAL COOLING
CONDITIONS NOT NEARLY AS FAVORABLE...WITH PATCHES OF STRATO-CU
BLANKETING THE AREA AND MOISTER LOWER LEVELS THAN THIS TIME
YESTERDAY. TEMPERATURES HAVE BEEN SLOWER TO FALL AND RANGE FROM
THE 50S INLAND TO AROUND 60 AT THE COAST. AS DESCRIBED IN PREVIOUS
DISCUSSION BELOW...EXPECT A RELATIVELY MILD NIGHT. WILL LIKELY SEE
FOG DEVELOP OVERNIGHT MOST LOCATIONS.
SURFACE TROUGH REMAINING JUST TO THE EAST OF LOCAL COASTAL WATERS
WILL SHIFT FARTHER WEST CLOSER TO THE CAROLINA COAST THROUGH THIS
EVENING BEFORE DISSIPATING OVERNIGHT. LIGHT NORTHEAST FLOW ON WEST
SIDE OF TROUGH WILL SHIFT MORE EASTERLY ESPECIALLY ALONG THE COAST
AS IT SHIFTS CLOSER. OVERALL WEAK GRADIENT WITH WINDS REMAINING 5
MPH OR LESS MOST PLACES AT THE SURFACE. RUC SOUNDINGS SHOWING AN
OVERALL WARMING AND DRYING OF THE COLUMN AT LOW LEVELS AS WARMER
AIR MAKES ITS WAY IN ALOFT AND MIXING OCCURS THROUGH TODAY...BUT
DECENT ON SHORE SE FLOW AT H85 CONTINUING TO BRING MOISTURE AND
SOME CLOUDS ON SHORE MAINLY OVER SC.
ON SHORE FLOW WILL CAPTURE SOME OF THE MARINE INFLUENCE CONTINUING
TO BRING HIGHER DEWPOINT AIR INLAND AS WINDS SHIFT BECOMING MORE
EASTERLY. THE DEWPOINTS ALONG THE COAST WILL REMAIN IN THE 50S
THROUGH MOST OF THE NIGHT WHILE INLAND DEWPOINTS WILL BE IN THE
MID 40S. WAA WILL CONTINUE WITH SW FLOW ABOVE THE SURFACE. 850
TEMPS AROUND 4 TO 5 C THIS MORNING WILL RISE UP TO AROUND 8C BY
DAYBREAK ON SUNDAY. LOW LEVEL FLOW WILL CONTINUE TO COME AROUND
FROM S-SE TO SW OVERNIGHT WHILE SURFACE WINDS BECOME VERY LIGHT
AND VARIABLE TO NEAR CALM. CLOUDS ASSOCIATED WITH COASTAL TROUGH
MAY MOVE ON SHORE THROUGH THIS EVENING AS H85 FLOW CONTINUES OUT
OF THE SE BEFORE SHIFTING TO S-SW OVERNIGHT. THE SFC TROUGH AXIS
SHIFTS A LITTLE FARTHER WEST BUT DISSIPATES OVERNIGHT AS HIGH
PRESSURE CONTINUES TO RIDGE BACK INTO THE CAROLINAS. OVERALL VERY
WEAK PRESSURE PATTERN EXPECTED WITH CALM WINDS. FOR NOW WILL KEEP
MOST CLOUDS OUT OF THE EQUATION ALLOWING FOR MORE IDEAL
RADIATIONAL COOLING AND DENSER FOG THREAT...BUT THE EXTENT OF FOG
WILL DEPEND ON HOW MUCH CLOUD COVER THERE WILL BE...WHICH WILL BE
THE FORECAST CHALLENGE OVERNIGHT.
TEMPS WILL DROP OFF AS WE RADIATE OUT OVER MOST PLACES BUT
WAA...INCREASED LOW LEVEL MOISTURE AND SOME CLOUDS WILL KEEP TEMPS
AND SFC DEWPOINTS HIGHER THAN PREVIOUS NIGHTS. FORECAST LOWS WILL
THEREFORE DROP TO THE LOW TO MID 40S MOST PLACES INLAND AND CLOSER
TO 50 ALONG THE COAST.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...HIGH PRESSURE WILL SHIFT OFF THE COAST SUNDAY
AND RESULT IN WARMING S-SW FLOW THROUGH THE PERIOD. THERE WILL BE
SOME INCREASE IN CLOUDS MONDAY NIGHT AS A FRONTAL SYSTEM APPROACHES
FROM THE WEST...OTHERWISE FAIR WEATHER IS EXPECTED. HIGHS WILL
MODERATE SLIGHTLY EACH DAY...MODERATING FROM THE LOWER 70S SUNDAY TO
THE MIDDLE 70S MONDAY. LOWS SUNDAY NIGHT WILL FALL TO THE UPPER 40S
TO LOWER 50S WITH MID TO UPPER 50S EXPECTED MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 300 PM SATURDAY...DAYBREAK TUESDAY AN UPPER TROUGH AXIS WILL
BE POSITIONED ROUGHLY ALONG THE MISSISSIPPI VALLEY...WITH SURFACE
HIGH PRESSURE SITUATED OFFSHORE OF THE CAROLINAS. EARLY TUESDAY A
WARM FRONT WILL RESIDE NORTH OF THE AREA...SO NO MENTIONABLE POP
VALUES PLANNED UNTIL TUESDAY NIGHT AS A COLD FRONT BREAKS EAST OF
THE APPALACHIAN MOUNTAINS. FRONTAL PASSAGE BASED ON AN GFS/ECMWF
CONSENSUS SOMETIME WEDNESDAY EITHER SIDE OF MIDDAY. SHRA TAPERING
OFF AND COLD AIR ADVECTION REGIME WEDNESDAY NIGHT AND A CLEARING
TREND INTO EARLY THURSDAY.
HENCE A DRY FORECAST DAY 6/7 FRI/SAT ALTHOUGH WE MAY EXPECT RETURN
FLOW NEXT WEEKEND AS THE PATTERN SHOWS A PROGRESSIVE NATURE.
TEMPERATURES 7-10 DEG F ABOVE NORMAL TUE/WED IN WARM SECTOR OF THE
APPROACHING FRONT...KNOCKED DOWN TO NORMAL DIURNAL TEMPERATURE
CURVES FOR NOVEMBER THU/FRI...THEN WARMING INTO NEXT SATURDAY.
THANKSGIVING DAY LOOKS SUNNY AND COOL. THE COLDEST MORNING IN THE
EXTENDED FORECAST LOOKS TO BE FRIDAY MORNING AS THE HIGH SETTLES
OVERHEAD BENEATH A CLEAR DOME...SO FREEZING TEMPS POSSIBLE THEN.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
AS OF 00Z...TERMINALS ARE VFR THIS EVENING. IR SATELLITE IMAGERY IS
DETECTING ONLY PATCHY MID-LEVEL CLOUDS.
ALL GUIDANCE HAS COME TOGETHER DEPICTING A WIDESPREAD FOG EVENT
DEVELOPING GENERALLY AFTER MIDNIGHT AFFECTING THE INLAND TERMINALS.
WITH SCATTERED SKIES INLAND AREAS DEVELOPING THIS EVENING NEARLY
IDEAL RADIATIONAL COOLING CONDITIONS ARE EXPECTED. AS SURFACE
TEMPERATURES COOL WINDS SHOULD FULLY DECOUPLE ALLOWING MINIMUMS TO
DROP FURTHER...EXCEEDING THE CROSSOVER TEMPERATURES BY LATE
EVENING/MIDNIGHT. IFR VISIBILITIES SHOULD DEVELOP AT FLO/LBT SHORTLY
AFTER MIDNIGHT WITH LIFR/VLIFR CONDITIONS DEVELOPING BY 08-09Z. AT
THE COASTAL TERMINALS GUIDANCE IS SPLIT ON A DENSE FOG SCENARIO.
MORE SIGNIFICANT LAYERS OF LOW/MID-LEVEL MOISTURE SHOULD INHIBIT FOG
DEVELOPMENT OVERALL. BASED ON THIS WILL SIDE WITH THE MORE
OPTIMISTIC SOLUTION AND ONLY INDICATE MVFR ATTM. BUT IF
MOISTURE/CLOUDS ARE LESS THAN ANTICIPATED THEN IFR VISIBILITIES
COULD CERTAINLY OCCUR...ESPECIALLY AROUND SUNRISE.
EXPECT FLO/LBT TERMINALS TO IMPROVE TO VFR 13-15Z WITH COASTAL
TERMINALS BECOMING VFR 12-14Z. VFR EXPECTED THE REMAINDER OF THE
DAY WITH LIGHT SOUTHWEST TO WEST WINDS BECOMING SOUTH TO SOUTHWEST
BY AFTERNOON.
EXTENDED OUTLOOK...LOW CONFIDENCE IN FOG MONDAY/TUESDAY MORNINGS AND
ISOLATED SHOWERS DURING THE AFTERNOONS. SHOWERS ASSOCIATED WITH A
COLD FRONT MAY IMPACT THE TERMINALS ON WEDNESDAY. VFR THURSDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10 PM SATURDAY...NO CHANGES TO THE FORECAST OR CONDITIONS
OVER THE COASTAL WATERS SINCE LAST UPDATE. LIGHT EASTERLY FLOW
WITH SEAS IN THE 2 TO 3 FT RANGE PREVAIL. PREVIOUS DISCUSSIONS
FOLLOW:
LATEST OBS SHOW SEAS IN THE 2 TO 3 FT RANGE WITH A LIGHT EASTERLY
WIND. WINDS WILL BECOME MORE VARIABLE AS SURFACE RIDGE AXIS MOVES
OVERHEAD...OTHERWISE EXPECT LITTLE CHANGE IN SEA HEIGHT OVERNIGHT.
PREVIOUS DISCUSSION FOLLOWS:
WINDS WILL SHIFT AROUND TO THE E-SE THROUGH THIS EVENING AS TROUGH
JUST TO THE EAST OF LOCAL WATERS SHIFTS A LITTLE FARTHER WEST
THROUGH THIS EVENING BEFORE DISSIPATING BY DAYBREAK. OVERALL WEAK
HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE CAROLINAS AS IT
SHIFTS FARTHER OFF SHORE OVERNIGHT. THEREFORE EXPECT SFC WINDS TO
BECOME LIGHT WEST OR VARIABLE OVERNIGHT AROUND 5 TO 10 KTS. PATCHY
CU MAY CONTINUE TO MOVE OVER THE LOCAL WATERS OR DEVELOP ALONG THE
SFC TROUGH. CAN NOT RULE OUT A SPRINKLE AS TROUGH MOVES SLIGHTLY
CLOSER TO THE COAST THIS EVENING BEFORE WEAKENING. SLIGHTLY LONGER
PERIOD E-NE SWELL COMING AROUND THE HIGH PRESSURE WILL COMBINE
WITH LOCALLY MINIMAL WIND WAVE TO PRODUCE SEAS IN THE 2 TO 3 FT
RANGE MOST WATERS WITH A FEW 4 FTERS IN OUTER WATERS.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...LIGHT AND VARIABLE WINDS SUNDAY WILL BECOME S
TO SW DURING THE AFTERNOON AND CONTINUE THROUGH MONDAY NIGHT.
SPEEDS OF 15 KT OR LESS ARE EXPECTED THROUGH THE PERIOD WITH SEAS
WILL OF 2 TO 4 FT.
LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 300 PM SATURDAY...TUESDAY THROUGH THURSDAY LOOKS UNSETTLED
AND ROUGH ON THE 0-20NM WATERS...PRIMARILY DUE TO A COLD FRONTAL
PASSAGE WEDNESDAY. PRE-FRONT SW WINDS LATE TUESDAY...AND POST-
FRONT NW WINDS LATE WED MAY BOTH REQUIRE AN ADVISORY...HENCE WE
MAY SEE AN ADVISORY FROM TUESDAY NIGHT THROUGH WEDNESDAY NIGHT
BASED ON CURRENT TIMING AND STRENGTH OF THE APPROACHING FRONT.
ADDITIONALLY...WE MAY SEE A FEW TSTMS OVER THE WATERS WEDNESDAY.
THE SEA SPECTRUM TUE-THU WILL BE MARKED BY E WAVES 2-3 FEET AT 10
SECONDS...WITH GROWING SSW WIND-WAVES/BUILDING SOUTHERLY CHOP AND
SLOP. EXPECT A WIND-SHIFT TO NW WED AFTERNOON...CHANGING DIRECTION
OF THE SHORT PERIOD WAVES. THE COLD AIR ADVECTION BEHIND THE FRONT
WILL BRING NW WIND GUSTS TO 25-30 KNOTS WEDNESDAY AFTERNOON AND
NIGHT. THURSDAY OR THANKSGIVING DAY...A DAY OF IMPROVEMENT BUT A
BIT ROUGH IN THE MORNING FROM NNW WINDS...HIGHEST OFFSHORE. NEAR
SHORE CONDITIONS WILL IMPROVE THE QUICKEST EARLY THURSDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...REK
NEAR TERM...REK/RGZ
SHORT TERM...RAN
LONG TERM...MJC
AVIATION...DCH
MARINE...MJC/REK/RGZ/RAN
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
656 PM EST SAT NOV 19 2011
.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFFSHORE THIS WEEKEND AND INTO EARLY NEXT
WEEK. TEMPERATURES WILL BEGIN TO WARM OVER THE WEEKEND AS SOUTHERLY
WINDS DEVELOP. A COLD FRONT WILL MOVE THROUGH WEDNESDAY. COOLER
WEATHER IS EXPECTED LATE NEXT WEEK AS HIGH PRESSURE BUILDS IN.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 7 PM SATURDAY...QUITE A DIFFERENCE FROM 24 HOURS AGO.
RADIATIONAL COOLING CONDITIONS NOT NEARLY AS FAVORABLE...WITH
PATCHES OF STRATO-CU BLANKETING THE AREA AND MOISTER LOWER LEVELS
THAN THIS TIME YESTERDAY. TEMPERATURES HAVE BEEN SLOWER TO FALL
AND RANGE FROM THE 50S INLAND TO AROUND 60 AT THE COAST. AS
DESCRIBED IN PREVIOUS DISCUSSION BELOW...EXPECT A RELATIVELY MILD
NIGHT. WILL LIKELY SEE FOG DEVELOP OVERNIGHT MOST LOCATIONS.
SURFACE TROUGH REMAINING JUST TO THE EAST OF LOCAL COASTAL WATERS
WILL SHIFT FARTHER WEST CLOSER TO THE CAROLINA COAST THROUGH THIS
EVENING BEFORE DISSIPATING OVERNIGHT. LIGHT NORTHEAST FLOW ON WEST
SIDE OF TROUGH WILL SHIFT MORE EASTERLY ESPECIALLY ALONG THE COAST
AS IT SHIFTS CLOSER. OVERALL WEAK GRADIENT WITH WINDS REMAINING 5
MPH OR LESS MOST PLACES AT THE SURFACE. RUC SOUNDINGS SHOWING AN
OVERALL WARMING AND DRYING OF THE COLUMN AT LOW LEVELS AS WARMER
AIR MAKES ITS WAY IN ALOFT AND MIXING OCCURS THROUGH TODAY...BUT
DECENT ON SHORE SE FLOW AT H85 CONTINUING TO BRING MOISTURE AND
SOME CLOUDS ON SHORE MAINLY OVER SC.
ON SHORE FLOW WILL CAPTURE SOME OF THE MARINE INFLUENCE CONTINUING
TO BRING HIGHER DEWPOINT AIR INLAND AS WINDS SHIFT BECOMING MORE
EASTERLY. THE DEWPOINTS ALONG THE COAST WILL REMAIN IN THE 50S
THROUGH MOST OF THE NIGHT WHILE INLAND DEWPOINTS WILL BE IN THE
MID 40S. WAA WILL CONTINUE WITH SW FLOW ABOVE THE SURFACE. 850
TEMPS AROUND 4 TO 5 C THIS MORNING WILL RISE UP TO AROUND 8C BY
DAYBREAK ON SUNDAY. LOW LEVEL FLOW WILL CONTINUE TO COME AROUND
FROM S-SE TO SW OVERNIGHT WHILE SURFACE WINDS BECOME VERY LIGHT
AND VARIABLE TO NEAR CALM. CLOUDS ASSOCIATED WITH COASTAL TROUGH
MAY MOVE ON SHORE THROUGH THIS EVENING AS H85 FLOW CONTINUES OUT
OF THE SE BEFORE SHIFTING TO S-SW OVERNIGHT. THE SFC TROUGH AXIS
SHIFTS A LITTLE FARTHER WEST BUT DISSIPATES OVERNIGHT AS HIGH
PRESSURE CONTINUES TO RIDGE BACK INTO THE CAROLINAS. OVERALL VERY
WEAK PRESSURE PATTERN EXPECTED WITH CALM WINDS. FOR NOW WILL KEEP
MOST CLOUDS OUT OF THE EQUATION ALLOWING FOR MORE IDEAL
RADIATIONAL COOLING AND DENSER FOG THREAT...BUT THE EXTENT OF FOG
WILL DEPEND ON HOW MUCH CLOUD COVER THERE WILL BE...WHICH WILL BE
THE FORECAST CHALLENGE OVERNIGHT.
TEMPS WILL DROP OFF AS WE RADIATE OUT OVER MOST PLACES BUT
WAA...INCREASED LOW LEVEL MOISTURE AND SOME CLOUDS WILL KEEP TEMPS
AND SFC DEWPOINTS HIGHER THAN PREVIOUS NIGHTS. FORECAST LOWS WILL
THEREFORE DROP TO THE LOW TO MID 40S MOST PLACES INLAND AND CLOSER
TO 50 ALONG THE COAST.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...HIGH PRESSURE WILL SHIFT OFF THE COAST SUNDAY
AND RESULT IN WARMING S-SW FLOW THROUGH THE PERIOD. THERE WILL BE
SOME INCREASE IN CLOUDS MONDAY NIGHT AS A FRONTAL SYSTEM APPROACHES
FROM THE WEST...OTHERWISE FAIR WEATHER IS EXPECTED. HIGHS WILL
MODERATE SLIGHTLY EACH DAY...MODERATING FROM THE LOWER 70S SUNDAY TO
THE MIDDLE 70S MONDAY. LOWS SUNDAY NIGHT WILL FALL TO THE UPPER 40S
TO LOWER 50S WITH MID TO UPPER 50S EXPECTED MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 300 PM SATURDAY...DAYBREAK TUESDAY AN UPPER TROUGH AXIS WILL
BE POSITIONED ROUGHLY ALONG THE MISSISSIPPI VALLEY...WITH SURFACE
HIGH PRESSURE SITUATED OFFSHORE OF THE CAROLINAS. EARLY TUESDAY A
WARM FRONT WILL RESIDE NORTH OF THE AREA...SO NO MENTIONABLE POP
VALUES PLANNED UNTIL TUESDAY NIGHT AS A COLD FRONT BREAKS EAST OF
THE APPALACHIAN MOUNTAINS. FRONTAL PASSAGE BASED ON AN GFS/ECMWF
CONSENSUS SOMETIME WEDNESDAY EITHER SIDE OF MIDDAY. SHRA TAPERING
OFF AND COLD AIR ADVECTION REGIME WEDNESDAY NIGHT AND A CLEARING
TREND INTO EARLY THURSDAY.
HENCE A DRY FORECAST DAY 6/7 FRI/SAT ALTHOUGH WE MAY EXPECT RETURN
FLOW NEXT WEEKEND AS THE PATTERN SHOWS A PROGRESSIVE NATURE.
TEMPERATURES 7-10 DEG F ABOVE NORMAL TUE/WED IN WARM SECTOR OF THE
APPROACHING FRONT...KNOCKED DOWN TO NORMAL DIURNAL TEMPERATURE
CURVES FOR NOVEMBER THU/FRI...THEN WARMING INTO NEXT SATURDAY.
THANKSGIVING DAY LOOKS SUNNY AND COOL. THE COLDEST MORNING IN THE
EXTENDED FORECAST LOOKS TO BE FRIDAY MORNING AS THE HIGH SETTLES
OVERHEAD BENEATH A CLEAR DOME...SO FREEZING TEMPS POSSIBLE THEN.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AS OF 00Z...TERMINALS ARE VFR THIS EVENING. IR SATELLITE IMAGERY IS
DETECTING ONLY PATCHY MID-LEVEL CLOUDS.
ALL GUIDANCE HAS COME TOGETHER DEPICTING A WIDESPREAD FOG EVENT
DEVELOPING GENERALLY AFTER MIDNIGHT AFFECTING THE INLAND TERMINALS.
WITH SCATTERED SKIES INLAND AREAS DEVELOPING THIS EVENING NEARLY
IDEAL RADIATIONAL COOLING CONDITIONS ARE EXPECTED. AS SURFACE
TEMPERATURES COOL WINDS SHOULD FULLY DECOUPLE ALLOWING MINIMUMS TO
DROP FURTHER...EXCEEDING THE CROSSOVER TEMPERATURES BY LATE
EVENING/MIDNIGHT. IFR VISIBILITIES SHOULD DEVELOP AT FLO/LBT SHORTLY
AFTER MIDNIGHT WITH LIFR/VLIFR CONDITIONS DEVELOPING BY 08-09Z. AT
THE COASTAL TERMINALS GUIDANCE IS SPLIT ON A DENSE FOG SCENARIO.
MORE SIGNIFICANT LAYERS OF LOW/MID-LEVEL MOISTURE SHOULD INHIBIT FOG
DEVELOPMENT OVERALL. BASED ON THIS WILL SIDE WITH THE MORE
OPTIMISTIC SOLUTION AND ONLY INDICATE MVFR ATTM. BUT IF
MOISTURE/CLOUDS ARE LESS THAN ANTICIPATED THEN IFR VISIBILITIES
COULD CERTAINLY OCCUR...ESPECIALLY AROUND SUNRISE.
EXPECT FLO/LBT TERMINALS TO IMPROVE TO VFR 13-15Z WITH COASTAL
TERMINALS BECOMING VFR 12-14Z. VFR EXPECTED THE REMAINDER OF THE
DAY WITH LIGHT SOUTHWEST TO WEST WINDS BECOMING SOUTH TO SOUTHWEST
BY AFTERNOON.
EXTENDED OUTLOOK...LOW CONFIDENCE IN FOG MONDAY/TUESDAY MORNINGS AND
ISOLATED SHOWERS DURING THE AFTERNOONS. SHOWERS ASSOCIATED WITH A
COLD FRONT MAY IMPACT THE TERMINALS ON WEDNESDAY. VFR THURSDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 7 PM SATURDAY...LATEST OBS SHOW SEAS IN THE 2 TO 3 FT RANGE
WITH A LIGHT EASTERLY WIND. WINDS WILL BECOME MORE VARIABLE AS
SURFACE RIDGE AXIS MOVES OVERHEAD...OTHERWISE EXPECT LITTLE CHANGE
IN SEA HEIGHT OVERNIGHT. PREVIOUS DISCUSSION FOLLOWS:
WINDS WILL SHIFT AROUND TO THE E-SE THROUGH THIS EVENING AS TROUGH
JUST TO THE EAST OF LOCAL WATERS SHIFTS A LITTLE FARTHER WEST
THROUGH THIS EVENING BEFORE DISSIPATING BY DAYBREAK. OVERALL WEAK
HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE CAROLINAS AS IT
SHIFTS FARTHER OFF SHORE OVERNIGHT. THEREFORE EXPECT SFC WINDS TO
BECOME LIGHT WEST OR VARIABLE OVERNIGHT AROUND 5 TO 10 KTS. PATCHY
CU MAY CONTINUE TO MOVE OVER THE LOCAL WATERS OR DEVELOP ALONG THE
SFC TROUGH. CAN NOT RULE OUT A SPRINKLE AS TROUGH MOVES SLIGHTLY
CLOSER TO THE COAST THIS EVENING BEFORE WEAKENING. SLIGHTLY LONGER
PERIOD E-NE SWELL COMING AROUND THE HIGH PRESSURE WILL COMBINE
WITH LOCALLY MINIMAL WIND WAVE TO PRODUCE SEAS IN THE 2 TO 3 FT
RANGE MOST WATERS WITH A FEW 4 FTERS IN OUTER WATERS.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...LIGHT AND VARIABLE WINDS SUNDAY WILL BECOME S
TO SW DURING THE AFTERNOON AND CONTINUE THROUGH MONDAY NIGHT.
SPEEDS OF 15 KT OR LESS ARE EXPECTED THROUGH THE PERIOD WITH SEAS
WILL OF 2 TO 4 FT.
LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 300 PM SATURDAY...TUESDAY THROUGH THURSDAY LOOKS UNSETTLED
AND ROUGH ON THE 0-20NM WATERS...PRIMARILY DUE TO A COLD FRONTAL
PASSAGE WEDNESDAY. PRE-FRONT SW WINDS LATE TUESDAY...AND POST-
FRONT NW WINDS LATE WED MAY BOTH REQUIRE AN ADVISORY...HENCE WE
MAY SEE AN ADVISORY FROM TUESDAY NIGHT THROUGH WEDNESDAY NIGHT
BASED ON CURRENT TIMING AND STRENGTH OF THE APPROACHING FRONT.
ADDITIONALLY...WE MAY SEE A FEW TSTMS OVER THE WATERS WEDNESDAY.
THE SEA SPECTRUM TUE-THU WILL BE MARKED BY E WAVES 2-3 FEET AT 10
SECONDS...WITH GROWING SSW WIND-WAVES/BUILDING SOUTHERLY CHOP AND
SLOP. EXPECT A WIND-SHIFT TO NW WED AFTERNOON...CHANGING DIRECTION
OF THE SHORT PERIOD WAVES. THE COLD AIR ADVECTION BEHIND THE FRONT
WILL BRING NW WIND GUSTS TO 25-30 KNOTS WEDNESDAY AFTERNOON AND
NIGHT. THURSDAY OR THANKSGIVING DAY...A DAY OF IMPROVEMENT BUT A
BIT ROUGH IN THE MORNING FROM NNW WINDS...HIGHEST OFFSHORE. NEAR
SHORE CONDITIONS WILL IMPROVE THE QUICKEST EARLY THURSDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...REK/RGZ
SHORT TERM...RAN
LONG TERM...MJC
AVIATION...DCH
MARINE...MJC/REK/RGZ/RAN
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1037 AM CST FRI NOV 18 2011
.DISCUSSION...
MAIN CHANGE FOR THE MORNING UPDATE WAS TO ADD SOME LOW POPS TO THE
SOUTHEASTERN COUNTIES. RADAR RETURNS HAVE BEEN ONGOING FROM SOUTH
CENTRAL ND INTO THE PARK RAPIDS AREA. HOWEVER...DEWPOINT
DEPRESSIONS ARE STILL LARGE AND NOTHING IS REACHING THE GROUND.
NAM HAS COME MORE INTO LINE WITH THE 06Z GFS...PRODUCING SOME QPF
THIS AFTERNOON OVER OUR SOUTHEASTERN COUNTIES. THE RUC AND HRRR
ALSO START TO SHOW A LITTLE BIT OF ACCUMULATING PRECIP. THINK THAT
IT WILL TAKE A WHILE TO SATURATE DOWN...BUT MODEL SOUNDINGS HAVE
THE LOWER LEVEL RH VALUES INCREASING DURING THE 18-21Z TIME FRAME.
INCLUDED SOME LOW POPS FOR RAIN OR SNOW SHOWERS IN OUR SOUTHEAST.
ALSO INCREASED CLOUDS AND DECREASED AFTERNOON TEMPERATURES A BIT.
&&
.AVIATION...
CONDITIONS WILL REMAIN VFR FOR THE NEXT FEW HOURS...BUT MVFR
CEILINGS WILL MOVE INTO KDVL BY 18Z OR SO. BORDERLINE VFR/MVFR
CEILINGS WILL SPREAD EASTWARD THROUGH THE FORECAST AREA LATER
DURING THE AFTERNOON AND SHOULD BE MVFR INTO TONIGHT. LIGHT AND
VARIABLE WINDS WILL PICK UP OUT OF THE WEST AND NORTHWEST BY THIS
EVENING.
&&
.PREV DISCUSSION... /ISSUED 422 AM CST FRI NOV 18 2011/
SHORT TERM...TODAY THROUGH SUNDAY
PRIMARY FORECAST CHALLENGES INCLUDE CLOUD TRENDS AND TEMPERATURES
TODAY AND THEN SNOW CHANCES AND AMOUNTS THROUGH THE DAY ON
SATURDAY AS A STRONG LOW PRESSURE SYSTEM MOVES ACROSS IOWA. GFS/
NAM/ECMWF/GEM IN GOOD AGREEMENT AND WILL USE A MODEL BLEND FOR
THIS FORECAST PACKAGE.
UPPER LEVEL SHORT-WAVE CURRENTLY ACROSS SOUTHERN SASKATCHEWAN
WILL MOVE ALONG THE INTERNATIONAL BORDER THROUGH THE DAY. THE
SURFACE LOW IS JUST SOUTH OF MINOT AND IS PROGGED TO WEAKEN AND
DROP SOUTHEAST TOWARD MINNEAPOLIS BY 00 UTC TONIGHT. REMAINING
LIGHT SNOW IS EXPECTED TO REMAIN NORTH OF THE CANADIAN BORDER...
ALTHOUGH LATEST MODELS SHOW SOME LIGHT QPF THIS AFTERNOON ACROSS
THE SOUTHEAST FORECAST AREA COINCIDENT WITH TRAILING COLD FRONT.
CROSS SECTIONS SUGGEST FAIRLY DRY LOW-LEVELS SO WILL KEEP FORECAST
DRY FOR NOW...BUT SOMETHING TO WATCH THROUGH THE DAY. BETTER
CHANCE FOR LIGHT SNOW...ALBEIT SLIGHT...WILL BE ACROSS THE DEVILS
LAKE BASIN THIS AFTERNOON AS LOW STRATUS DECK ACROSS SOUTHERN
CANADA CREEPS SOUTHWARD THROUGH THE DAY.
OVERALL...EXPECT FILTERED SUNSHINE TODAY THROUGH MID-HIGH LEVEL
CLOUDS. STRONG COLD AIR ADVECTION WILL ACCOMPANY FRONTAL PASSAGE...
BUT SHOULD OCCUR LATE ENOUGH IN THE DAY FOR HIGH TEMPERATURES TO
STILL REACH THE LOWER 20S IN THE NORTHWEST TO NEAR 40 DEGREES IN
THE FAR SOUTH. COLDER THERMAL PROFILE...HOWEVER...WILL ALLOW
NIGHTTIME LOWS TO DIP INTO THE SINGLE DIGITS ACROSS THE NORTH WHERE
SOME CLEARING IS POSSIBLE TO THE LOW 20S ACROSS THE SOUTH.
ATTENTION THEN TURNS TO SATURDAY AS A STRONG SURFACE LOW EJECTS
FROM EASTERN CO AND INTO SOUTHERN WI 06 UTC SUNDAY. BEST LINKAGE
BETWEEN STRONG 850 TO 700 HPA FRONTOGENESIS AND 500 TO 300 HPA
Q-VECTOR CONVERGENCE WILL BE ALONG A LINE FROM PIERRE TO WATERTOWN
TO ST CLOUD WHERE A SOLID 4 TO 6 INCHES OF SNOW IS POSSIBLE.
FARTHER NORTH ACROSS THE EXTREME SOUTHERN FORECAST AREA...EXPECT 1
TO 3 INCHES OF NEW ACCUMULATION. A WINTER WEATHER ADVISORY MAY BE
NEEDED...BUT WILL LET LATER SHIFTS EVALUATE POSSIBLE HEADLINES.
THERE SHOULD BE A SHARP CUT-OFF IN PRECIPITATION FROM SOUTH TO
NORTH GIVEN NORTHERLY WIND AROUND SOUTHERN ALBERTA HIGH ADVECTING
DRIER AIR INTO THE REGION. FARGO MAY SEE AROUND A HALF INCH WITH
AREAS NORTH OF THE HIGHWAY 200 CORRIDOR SEEING LITTLE TO NO
ACCUMULATION. TEMPERATURES WILL CONTINUE TO FALL ON SATURDAY WITH
REINFORCING SHOTS OF COLD AIR. HIGHS WILL TOP OUT IN THE LOWER
TEENS TO LOWER 20S.
REMAINING SNOW WILL MOVE OUT OF THE REGION SATURDAY NIGHT...
ALLOWING FOR A DRY SUNDAY WITH INCREASING SUNSHINE. IF ENOUGH
CLEARING OCCURS EARLY IN THE DAY...MORNING LOWS WILL DROP INTO THE
SINGLE DIGITS BELOW ZERO IN SOME PLACES. HIGHS WILL ONLY CLIMB
INTO THE TEENS TO LOWER 20S.
LONG TERM...SUNDAY NIGHT THROUGH THANKSGIVING
EXPECT DRY WEATHER WITH TEMPS WARMING ABOVE NORMAL BY WED. AN
UPPER RIDGE IS WELL PROGGED BY ALL MODELS...SO EXPECT TEMPS TO
WARM ALONG WITH DRY WEATHER THROUGH AT LEAST THANKSGIVING. NO
MAJOR STORMS ARE ON THE HORIZON FOR THE EXTENDED PERIOD.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
JR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
100 AM EST FRI NOV 18 2011
.SYNOPSIS...
WESTERLY WINDS WILL BRING LAKE EFFECT SNOWS TO THE SNOW BELT OF
NORTHWESTERN PENNSYLVANIA TONIGHT...BUT HIGH PRESSURE WILL BUILD IN
QUICKLY ON FRIDAY MORNING. THE HIGH WILL SET UP ALONG THE EAST COAST
FOR THIS WEEKEND. A WEAK COLD FRONT WILL LIKELY SAG SOUTHWARD
THROUGH THE AREA LATE SUNDAY. A DEVELOPING STORM SYSTEM IN THE
MISSISSIPPI VALLEY COULD AFFECT CENTRAL PA EITHER TUESDAY OR
WEDNESDAY OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
OOZ HRRR AND 02Z RUC CONFIRMS WHAT WE/RE SEEING ON THE REGIONAL
88D MOSAIC THIS EVENING...WHICH IS A RATHER FRAGMENTED OR CELLUAR
PATTERN TO THE LAKE EFFECT AND ORORGAPHIC SNOW SHOWERS THAT WILL
AFFECT THE NW MTNS OVERNIGHT...AND TO A MUCH LESSER DEGREE - THE
LAUREL HIGHLANDS.
COLDEST MID-LEVEL TEMPS /WITHIN THE 700-500 MB LAYER/ WILL BE
EXITING TO THE NE OF THE REGION OVERNIGHT...THOUGH THE THERMAL
TROUGH AT 850 MB /WITH MIN TEMPS AROUND -10C/ WILL BE CENTERED
ACROSS NRN AND WESTERN PENN THROUGH 12Z FRIDAY.
A FAIRLY WELL-ALIGNED BUT GRADUALLY VEERING WEST TO NW BOUNDARY
LAYER FLOW WILL MAINTAIN NUMEROUS /AND BRIEFLY MDT-HVY/ SNOW
SHOWERS ACROSS THE NW MTNS. ACCUMS NEAR...AND TO THE WEST OF KBFD
WILL NOT ENOUGH TO WARRANT A LES ADVISORY...AND WILL BE MAINLY
BETWEEN 1-2 INCHES OVER A 12-16 HOUR PERIOD. LOCALIZED 3 INCH
AMOUNTS ARE POSSIBLE NEAR AND TO THE WEST OF KBFD...MAINLY TO THE
NORTH OF ROUTE 6.
NARROW BANDS OF LIGHTER SNOW SHOWERS ACROSS THE LAURELS WILL
BRING A LIGHT COATING OF SNOW TO MANY LOCATIONS...WITH UP TO ONE
INCH POSSIBLE ON A FEW OF THE RIDGES WEST OF RT 219.
FOR THE SOUTHEAST TWO THIRDS OF THE REGION...EXPECT A FEW FLURRIES
AND PERHAPS A BRIEF 2-5 MINUTE SNOW SHOWER THROUGH THE OVERNIGHT.
MIN TEMPS TONIGHT /AROUND 20F ACROSS THE NW MTNS AND LAUREL
HIGHLANDS...AND IN THE MID TO UPPER 20S THROUGHOUT THE CENTRAL AND
SE VALLEYS/ WILL BE 5-6F BELOW NORMAL.
THE WIND STAYS GUSTY FOR MUCH OF THE NIGHT DUE TO TIGHT P-GRAD.
GUSTS BETWEEN 25-30 MPH WILL BE COMMON ACROSS THE CENTRAL AND WRN
ZONES. A FEW GUSTS NEAR SNOW SHOWERS COULD RANGE UP TO 35 MPH.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
8H TEMPS RISE 10C THROUGH THE DAYLIGHT HRS...AND PUSH ANY
REMAINING LAKE EFFECT SNOW WELL TO THE NORTH IN THE EARLY MORNING.
REST OF THE SHORT TERM SHOULD BE CLEAR. SFC TEMPS MIGHT ONLY
REBOUND ABOUT 15F WITH SHALLOW COLD AIR STUBBORN TO GO AWAY...ESP
IN THE EASTERN VALLEYS. SFC HIGH PASSES TO OUR SOUTH DURING THE
DAY AND SETS UP LIKE A BERMUDA HIGH. CLEAR SKIES AND THE STUBBORN
COOLER AIR IN THE EAST WILL HELP THE ERN COLD SPOTS LIKE SEG AND
THV DIP INTO THE L20S. M-U20S LOOK GOOD FOR MINS ELSEWHERE ESP THE
RIDGES WHERE SRLY WIND WILL KEEP GOING LIGHTLY FOR MUCH OF THE
NIGHT.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO BE FORECAST
BY THE LONG TERM MODELS THROUGH AT LEAST THE BEGINNING OF NEXT
WEEK. THIS WILL KEEP TEMPERATURES NEAR TO ABOVE NORMAL THROUGH MUCH
OF THE PERIOD...WITH NO SIGNIFICANT PERIODS OF ARCTIC CHILL IN SITE
AS WE NOW INCLUDE THANKSGIVING DAY IN THIS FORECAST PACKAGE.
SHORTWAVE ENERGY IS FORECAST TO MAKE ITS WAY EAST BY THE MIDDLE OF
NEXT WEEK COMPLICATING THE UPPER FLOW PATTERN.
AS THE UPPER TROUGH BUILDS OVER THE WESTERN U.S. INTO THE
WEEKEND...THE SOUTHEASTERN RIDGE SHOULD PUSH WARMER AIR INTO OUR
REGION BY SATURDAY. THE 850 HPA TEMPERATURES ARE PREDICTED TO BE
1SD ABOVE NORMAL LATE SATURDAY ACROSS THE NW PART OF THE
STATE...AND AREA- WIDE ON SUNDAY. ANOTHER COLD FRONT APPROACHES
WITH THE NEXT CHC FOR SHOWERS LATER SUNDAY INTO MONDAY. THIS FRONT
IS FORECAST TO STALL OVER THE MID ATLANTIC REGION...WITH THE
POTENTIAL FOR A WAVE OF LOW PRESSURE BRINGING MORE PCPN INTO THE
REGION NEXT TUE/WED...BUT THE DETAILS AT THIS POINT ARE ANYTHING
BUT CLEAR.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
INTENSE BANDS OF SNOW SHOWERS OVER N PA AT 06Z. HEAVIEST BANDS
EAST OF BFD...AND ONLY A FEW FLURRIES EXPECTED AT IPT. BANDS
NORTH OF IPT EXTEND INTO SULLIVAN COUNTY...AND CLOUD BANDS
WELL INTO NJ. THUNDER REPORTED EARLIER ON THE SE SHORE OF
LAKE ONT. WILL CONTINUE TO MONITOR.
UPPER LOW MOVES ACROSS STATE TONIGHT WITH HIGH PRESSURE MOVING IN
BEHIND FOR FRI. THIS WILL BRING SNOW SHOWERS OFF OF THE LAKES
THROUGH SUNRISE TO THE NW MTNS...INCLUDING VARIABLE IFR TO VFR
CONDITIONS AT KBFD THROUGH THE OVERNIGHT. ELSEWHERE...THE AIRMASS
IS QUITE DRY...SO EXTENT OF THE SNOW SHOWERS AND LOW CIGS WILL BE
LIMITED TO THE NORTHWEST PART OF THE STATE WITH VFR ELSEWHERE.
WINDS OF 10-15 MPH GUSTING TO 25 MPH WILL GRADUALLY DIMINISH
LATE.
PERIOD OF VFR CONDITIONS FRI MORNING THROUGH SAT NIGHT AS A SW
FLOW OF MILD AIR DEVELOPS ON THE BACK SIDE OF THE HIGH.
OUTLOOK...
FRI-SAT...VFR. NO SIG WX.
SUN...GENERALLY VFR. MVFR IN SHOWERS POSS LATE.
MON-TUE...MVFR TS/SHRA/CIGS POSSIBLE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO/LAMBERT
SHORT TERM...DANGELO
LONG TERM...FITZGERALD/GARTNER
AVIATION...MARTIN/RXR
AREA FORECAST DISCUSSION
NWS SPOKANE WA
302 PM PST Fri Nov 18 2011
.SYNOPSIS...
Scattered clusters of heavy snow showers will continue to impact
most of eastern Washington and north Idaho through tonight ahead
of an arctic boundary moving in from the Northeast. As the front
moves through...drier and cooler weather is expected with the
largest threat of snow moving into southeast Washington and north
central Idaho on Saturday. Following a break in the weather
Sunday, unsettled weather will return for most of next week with
most of the snow expected to occur near the cascades and northern
mountains.
&&
.DISCUSSION...
Tonight...difficult forecast scenario continues to unfold late this
afternoon as a two distinct air masses remain fixed over the
Inland Northwest between a weakening frontal occlusion. Based on
surface wind directions...the front extended approximately from
the Coulee City area south toward the central Idaho Panhandle.
North of this boundary was a shallow..yet well defined arctic air-
mass with persistent snows extending from the Okanogan Highlands
east toward Sandpoint. Cloud tops in this region have warmed
considerably from this morning and we expect snow rates to ramp
down as well as much drier air works in below 850 mbs. There is
already evidence of this down the Purcell Trench as both Bonners
Ferry and Coeur d`Alene have seen their dewpoints plunge into the
upper teens. Farther west...the drier air will be slower to move
in so...we will extend the winter highlights for the NE Washington
mountains and Okanogan Highlands into the evening and mention
another 1-2" of snow possible.
South of the frontal occlusion...the atmosphere was very unstable for
this time of year. We continue to see showers develop over Adams
and Whitman counties with 45-50dbz which suggests the presence of
intense precipitation which was likely a mix of rain...snow...and
graupel. This activity will will continue to track to the
northeast...hitting southern portions of Spokane County...the
northern Palouse ...and western Columbia Basin. We would expect
this activity to dwindle some as the frontal occlusion weakens and
the potential instability begins to wane with the setting sun.
However any small ripple in the upper atmosphere will provide the
needed lift to generate a new batch of showers.
The toughest part of the forecast is what to do in the region between
the two air masses...i.e. Spokane and Coeur d`Alene area. The NAM
solution and even the GFS both suggest along the leading edge of
the arctic boundary we should be seeing some intense snow based on
a deep frontal lifting and a saturated dendritic layer. However
the radar is telling a different story. The latest HRRR solution
though does mesh with the current radar and really downplays the
GFS and NAM scenario. Thus we still expect we will see some snow
develop late this afternoon and early this evening...but it should
be significantly lighter than the .25" of liquid forecast by the
NAM. If the .25" were to develop between Spokane and Coeur d`Alene
we would see up to 3" of snow or more. However based on road temps
warmer than 35-40 and air temps still above freezing...at least
below 2000 feet it may have a hard time accumulating to that
depth. We will hold onto some light snow accumulations into the
evening...but based on the small accumulations...we will get rid
of the winter storm warnings and cover any localized situations
via short term forecasts. Once the arctic airmass passes
through...the threat of significant snowfall will taper off
rapidly. How far south and west the front gets tonight is tough to
determine...but we suspect it won`t drop into our southeast zones
until tomorrow morning. fx
Saturday through Sunday night: Overall, the forecast will begin
to trend drier from north to south as the cooler modified
Canadian air spills into the Inland NW. This will make for a brisk
breezy day for most locations north of Interstate 90 but little in
the way of snowfall. Further south, we will be monitoring one more
midlevel disturbance (vort lobe) that will skirt southern WA and
the Idaho Panhandle on Saturday keeping the potential for isolated
to scattered light snow showers throughout the day Saturday. This
feature will drop into the region from the northern tip of
Vancouver Island reaching the Cascades and southwestern Basin
Saturday morning then Blues...Palouse...and Camas Prairie Saturday
afternoon. The air mass will remain conditionally unstable with
modeled 700-500mb lapse rates remaining within the 7.5-8.5 C/km
range. While QPF amounts are suggested to be just a few
hundredths, the convective nature to the showers may lead to a
quick inch anywhere from Plain...along the extreme southern
Columbia Basin...Palouse... Blues Mtns...and potions of the Idaho
Panhandle mainly south of I-90. Temperatures will be well below
normal with highs only climbing into the 20`s to mid 30`s with
teens in the northern mountains. With little warming on Saturday
and fresh snow cover across most northern valleys, overnight lows
will be falling into the cold to very cold category. Winds will be
weakening but there is some uncertainty on the amount of clearing
aloft and potential for fog. The northwestern quadrant of the CWA
look to have the highest potential for clearing skies so adjusted
low temperatures well below model guidance for locations in the
Methow Valley, East Slopes, and Okanogan Country where single
digits to below zero. This may also be the case for the valleys of
northeastern WA and northern ID but with models hanging on to some
cloudiness...opted to only go single digits. If skies clear, it is
almost a given that locations like Deer Park, Priest Lake,
Sandpoint, Rathdrum, and Bonners Ferry will dip below zero due to
the fresh snow that has fallen. /sb
Monday through Friday: A warm front will move across the inland
northwest Monday afternoon. Strong southwesterly winds will usher
in some warmer 850 mb temperatures. Precipitation will start off
as snow Monday morning, and then by afternoon snow will change
over to rain across the basin, palouse and portions of the
Spokane/COE areas. Tuesday we continue the moist southwest flow
with showers continuing. Warmer air will continue to move north
so that all valleys will see rain or a rain/snow mix. An upper level
trough will approach the west coast Wednesday. Models start to
diverge on where to point the moisture as the trough digs off
southern California. The 12z ECMWF did trend toward the 12z GFS,
but it still remains faster, though not as fast as the Canadian.
Given the highly active weather pattern through the entire
extended forecast, kept chance of precipitation above climatology.
Monday temperatures start out at or below climatology, but as the
warmer air moves in late Monday temperatures will rise to at or
slightly above climatology through the remainder of the forecast.
/Nisbet
&&
.AVIATION...
18Z TAFs...Cold, unstable air mass setting up over Eastern WA and
Northern ID will continue to fuel snow showers through this evening.
The most organized snow shower activity will focus from KOMK to KCOE
along an approaching frontal boundary sagging in from the N/NE. A
midlevel wave dropping SE along this boundary is expected to
re-organize snow bands over the Spokane-Coeur D Alene corridor arnd
22z-02z. Aft 02z...a shallow cold front should slide into KGEG
strengthening NE flow and bring brief low-level drying. This
appears to be short-lived as another surge of moisture and warmer
air approaches from the SW strengthening low-level inversions and
potential for incr MVFR cigs aft 12z along with -SHSN at KEAT.
Otherwise -SHSN will be more hit or miss for KPUW and KLWS/KMWH
with the biggest concern being the present ifr fog and stratus which
should gradually lift into mvfr stratus or better this aftn. /sb
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 20 26 12 29 15 37 / 80 20 20 10 10 30
Coeur d`Alene 20 25 12 29 13 37 / 90 20 20 10 10 40
Pullman 22 29 17 32 16 37 / 70 40 20 10 10 20
Lewiston 29 35 22 37 25 44 / 50 50 20 10 10 20
Colville 15 25 9 28 12 33 / 50 10 10 10 20 60
Sandpoint 17 22 9 28 11 35 / 60 10 20 20 20 60
Kellogg 20 23 15 27 14 33 / 90 30 20 20 10 50
Moses Lake 19 32 10 32 17 37 / 20 30 10 10 10 30
Wenatchee 24 32 13 32 23 35 / 20 40 10 10 30 40
Omak 16 28 4 32 14 33 / 20 20 10 10 30 60
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning until 10 PM PST this evening for Central
Panhandle Mountains-Northern Panhandle.
WA...Winter Storm Warning until 10 PM PST this evening for
Northeast Mountains
Winter Weather Advisory until 10 PM PST this evening for
Okanogan Highlands.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
927 PM MST SAT NOV 19 2011
.UPDATE...
MOISTURE OVERRUNNING A STALLED COLD FRONT DRAPED OVER EAST-CENTRAL
UTAH AND WEST CENTRAL COLORADO...ALSO INFLUENCED BY CHANNELED MID-
LEVEL VORTICITY WILL CONTINUE TO BRING SNOW TO THE NORTHERN
MOUNTAINS AND ROAN PLATEAU OVERNIGHT. MODEL GUIDANCE INDICATED AN
ADDITIONAL 3 TO 5 INCHES OVER THE AREA SO WILL EXTEND HILITES THROUGH
12Z SUNDAY. SUSPECT COLD AIR PACKED INTO THE STEAMBOAT BASIN WILL
CONTINUE TO BRING SNOWFALL TO THE TOWN WITH AN ADDITIONAL 1 TO 3
INCHES LIKELY OVERNIGHT AND DECIDED TO KEEP WARNING GOING THERE AS
WELL. SNOWFALL TO BE MORE SPORADIC OVER THE CENTRAL YAMPA RIVER BASIN
SO HAVE LET THE WARNING FOR ZONE 2 EXPIRE. FULL MODEL SUITE HAS NOT
UPDATED AND NAM12 AND RUC13 DISAGREE WITH RESPECT TO QPF...SO
HESITANT TO ADJUST ADVISORY FOR THE CENTRAL MOUNTAINS.
UPDATED AVIATION DISCUSSION FOR THE 06Z TAF ISSUANCE. SEE BELOW.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY/...
HEALTHY SNOW AMOUNTS EXISTS NORTH OF THE SURFACE FRONT WHERE MOIST
SYMMETRIC INSTABILITY IN ADDITION TO THE OROGRAPHICS HAVE PLAYED A
SIGNIFICANT ROLE TODAY. SNOWFALL HAS EXCEEDED EXPECTATIONS ACROSS
MUCH OF NORTHWEST COLORADO TODAY. APPEARS THE SURFACE FRONT IS
LOCATED ON A LINE FROM CANYONLANDS NATIONAL PARK TO CRESTED BUTTE.
SATELLITE IMAGES SHOW A GRADUAL WARMING OF THE CLOUD TOPS...SO THE
CURRENT TREND IS FOR SNOW RATES TO DIMINISH DURING THE NEXT SEVERAL
HOURS. GRADIENT FLOW IS WEAKENING AND ALSO BACKING AROUND TO A
SOUTHWEST FLOW...THIS WILL SHELTER SPOTS THAT HAVE RECEIVED HEAVY
SNOWFALL TODAY. THIS PROCESS IS GRADUAL AND WIDESPREAD SNOW MAY NOT
END UNTIL MID TO LATE EVENING. SO HAVE EXTENDED AND UPGRADED WINTER
WEATHER HIGHLIGHTS EARLIER THIS AFTERNOON. REMOTE SENSORS ON THE
PARK RANGE AND FLAT TOP MOUNTAINS INDICATE 12+ INCHES OF SNOW THUS
FAR WITH SNOW WATER EQUIVALENT RATIOS NEARLY 15-20 TO 1.
THE STEADY STREAM OF PACIFIC MOISTURE ABATES...BUT NEVER STOPS AS WE
GO INTO SUNDAY. DYNAMICAL FORCING IS MINIMAL DURING THE PERIOD BUT
REMNANTS OF THE SURFACE FRONT WILL PROVIDE SOME LOW LEVEL FORCING.
THE NORTHERN MOUNTAINS WILL BE THE TARGET AGAIN WITH SOUTHWEST FACING
ASPECTS THE PREFERRED SPOTS FOR PRECIPITATION. PROGGED QPF AMOUNTS
IS LOW AND ANY MOUNTAIN SNOW ACCUMULATIONS WILL BE LIGHT AND
GENERALLY 3 INCHES OR LESS.
MOIST LAYER DEEPENS SUNDAY NIGHT AND MONDAY AS THE TROUGH AXIS
MOVES ACROSS THE DESERT SOUTHWEST. THIS WILL ENHANCE MOUNTAIN SNOW
AMOUNTS AND POSSIBLY ADDITIONAL WINTER WEATHER HIGHLIGHTS WILL BE
REQUIRED. GRADIENT FLOW IS WEAK AND THE BEST DYNAMICAL FORCING
STAYS SOUTH OF THE BORDER...BUT ISENTROPIC ANALYSIS DOES INDICATE
SOME MID LEVEL COOLING WILL OCCUR AND THIS WILL HELP TRIGGER
ADDITIONAL SNOWFALL.
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
MONDAY NIGHT-WEDNESDAY: THE UPPER TROUGH PASSES THROUGH NEW MEXICO
MONDAY NIGHT. MTN TOP WINDS VEER NW THROUGH THE EVENING. MOISTURE IS
INITIALLY DEEP ENOUGH TO CONTINUE TO PRODUCE THE LAST LIGHT
ACCUMULATIONS IN THE CO MTNS. COLDER TEMPERATURES EXPECTED MONDAY
NIGHT...THOUGH LINGERING CLOUDS IN CENTRAL COLORADO MAY MODIFY
THESE MIN TEMPS. A RIDGE AMPLIFIES OVER THE AREA ON TUESDAY FOR
THE BEGINNING OF A WARMING TREND IN THE MTNS BUT CAPPING THE
VALLEYS. THE RIDGE SHIFTS EAST TUESDAY NIGHT AND SW FLOW ALOFT ON
WEDNESDAY CONTINUES THE WARMING TREND ON THE SLOPES WITH VALLEYS
SHOWING LESS OF A WARMING TREND.
THURSDAY-FRIDAY: CLOUDS AND SW GRADIENT WINDS INCREASE ON
THANKSGIVING. VALLEY INVERSIONS MAY MIX OUT THURSDAY AFTERNOON FOR
THE MILDEST DAY OF THE WEEK. THE 12Z GFS/EC BOTH SHOW SHOWERS
STARTING ON SW-FACING SLOPES THURSDAY NIGHT AND BECOMING MORE
WIDESPREAD ON FRIDAY. COORDINATED WITH RIW CYS AND PUB TO INCREASE
POPS FOR THESE PERIODS. TROUGH PASSAGE IN THE AFTERNOON VEERS THE
FLOW TO NW WITH SHOWERS CURRENTLY TIMED TO LAST INTO THE EVENING.
SATURDAY: IN A CONTINUED HIGHLY AMPLIFIED PROGRESSIVE FLOW...HIGH
PRESSURE BUILDS IN FOR SATURDAY WITH ANOTHER TROUGH PASSAGE TIMED
FOR EARLY IN THE NEW WEEK.
&&
.AVIATION /FOR 06Z TAF ISSUANCE/
THE COLD FRONT REMAINED STATIONARY...STRETCHING FROM WEST TO EAST
JUST SOUTH OF THE I-70 CORRIDOR THIS EVENING. THE FRONT IS EXPECTED
TO REMAIN QUASI-STATIONARY UNTIL IT LIFTS NORTHWARD ON SUNDAY. SOUTH
OF THE FRONT GUSTY SOUTHWEST WINDS WILL BRING MOUNTAIN TURBULENCE AND
SCATTERED MOUNTAIN SNOW SHOWERS. ALONG AND NORTH OF THE FRONT...
CEILINGS WILL REMAIN LOW IN WIDESPREAD SNOWFALL TONIGHT. AREAS OF
MVFR...AND ISOLATED IFR CONDITIONS...ARE EXPECTED OVER THE HIGHER
ELEVATION AIRPORTS THROUGH TONIGHT. KCAG...KHDN....KSBS...KEGE...AND
KASE TERMINAL SITES WILL SEE LOWERED CEILINGS AND LOWERED VSBYS AT
TIMES IN SNOW SHOWERS. KRIL WILL HAVE DECREASING SHOWERS AND
INCREASING CIGS AND VSBY AFTER MIDNIGHT. MOUNTAIN TOPS WILL REMAIN
MOSTLY OBSCURED OVERNIGHT. SCATTERED SNOW SHOWERS WITH MVFR-LOCAL IFR
CEILINGS AND VSBYS WILL CONTINUE INTO SUNDAY. SNOW SHOWERS WILL
LARGELY DIMINISH SUNDAY EVENING...THOUGH A FEW LINGERING FLURRIES
MAY CONTINUE OVER MOUNTAIN PEAKS AND HIGH RIDGES.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR ZONES
009-010-012.
WINTER STORM WARNING UNTIL 6 AM MST SUNDAY FOR ZONES
004-005-013.
WINTER WEATHER ADVISORY UNTIL 6 AM MST SUNDAY FOR ZONE 003.
UT...NONE.
&&
$$
UPDATE.......NL
SHORT TERM...PF
LONG TERM....JOE
AVIATION.....JOE/NL
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1250 AM EST SUN NOV 20 2011
.SYNOPSIS...
HIGH PRESSURE CONTINUES TO DOMINATE THE WEATHER TONIGHT A COLD
FRONT WILL MOVE THROUGH TOMORROW NIGHT AND THEN STALL...FOLLOWED
BY MORE SEASONABLY CHILLY WEATHER NEXT WEEK. LOW PRESSURE MOVING
ALONG THIS STALLED FRONT SHOULD BRING RAIN...AND POSSIBLY SOME WET
SNOW TUESDAY NIGHT INTO WEDNESDAY. DRIER WEATHER IS EXPECTED TO
RETURN DURING THURSDAY AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1 AM UPDATE...
LIGHT SHOWERY BAND OF PRECIP MOVING THRU THE WRN FCST RGN PER
RADAR RETURNS...YET SUFFICIENT DRY AIR BELOW H6 IS MAKING IT
DIFFICULT FOR ANY PRECIP TO REACH THE SFC. WILL CONTINUE SLGT CHC
POPS FOR HIGHER TERRAIN ABOVE 500 FT AGL INTO 9Z.
TEMP TRENDS HAVE BEEN THE BIGGEST CHALLENGE. LATEST OBS HAVE SHOWN
A WARMING TREND PARTICULARLY ACROSS S/SE NEW ENGLAND. NEED TO
MODIFY MINS ACCORDINGLY WHICH ARE FAR TOO LOW. MID-LVL CLOUDS
STILL THICK ACROSS THE RGN WITH BLUSTERY SW FLOW. SEEMS A SAFE BET
WE ARE NOT GOING TO COOL DOWN APPRECIABLY INTO MORNING.
PREV DISCUSSION...
SHOWERY BAND OF PRECIP PROGRESSING EWD COINCIDENT WITH LIFT
ALONG THE 305K ISENTROPIC SFC PER RUC MESOANALYSIS /ROUGHLY AROUND
H6/. MOIST LAYER AT H6 PER ALY 00Z UPR AIR SOUNDING...BUT NOTE THE
ENCOMPASSING DRY AIR BELOW TO THE SFC. AMAZINGLY SEVERAL LOCALES
ACROSS MID-UPSTATE NY HAVE REPORTED TRACE PRECIP WITH CEILINGS OF
8-10 KFT...WHICH DOES ILLUSTRATE THE DIFFICULTY OF PRECIP REACHING
THE SFC.
WINDS REMAIN BLUSTERY OUT OF THE SW WITH GUSTS AROUND 30 MPH.
INFREQUENT GUSTS AROUND 15 TO 20 MPH FOR THE INTERIOR DUE TO
BOUNDARY LAYER DECOUPLING...NOT THE CASE FOR ELEVATIONS AOA 1000
FT AGL OR GREATER. WORCESTER AIRPORT REPORTING GUSTS OF AROUND 25 MPH.
VWP/S CONTINUE TO HIGHLIGHT H925 WINDS OF AROUND 50 MPH. MID-HIGH
LVL CLOUDS CONTINUE TO STREAM THRU THE RGN.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/...
SUNDAY...
LOW PRESSURE CENTER TRACKS THROUGH SOUTHEAST CANADA...WHILE TRAILING
COLD FRONT APPROACHES SOUTHERN NEW ENGLAND. SHOULD BE REACHING THE
WESTERN EDGE OF OUR COUNTY WARNING AREA BY 00Z MON. NOT MUCH
MOISTURE AVAILABLE WITH THE APPROACH OF THIS FRONT. EXPECTING SOME
INCREASE IN CLOUDS BUT POPS ARE DRY TO SLIGHT CHANCE. DO EXPECT
MIXING WITH PARTLY CLOUDY CONDITIONS...H925 WINDS START OUT AT 45 TO
50 KTS AT 12Z BUT DO DIMINISH OVER THE COURSE OF THE DAY. RESULT
SHOULD BE GUSTS OF 20 TO 30 MPH LATE MORNING AND ON ACROSS MUCH OF
THE INTERIOR...GUSTS 30 TO 40 MPH POSSIBLE ON THE CAPE AND ISLANDS.
MAX TEMPS IN THE UPPER 50S TO MID 60S.
SUNDAY NIGHT AND MONDAY...
SFC COLD FRNT SLIDES THRU THE RGN SUNDAY NIGHT AND WINDS BACK OUT OF
THE W/NW. HOWEVER FRONT STALLS JUST TO OUR SOUTH. MOISTURE POOLS
NEAR THE FRONT WITH WEAK LIFT...BUT TO OUR NORTH WILL BE A HIGH
PRESSURE SENDING DRIER AIR OUR WAY. AS A RESULT WILL ONLY GO WITH
SLGT CHC TO LOW CHC POPS FOR THE EXTREME S FCST ZONES SUN NIGHT.
MINS TO DROP OFF WITH NWLY FLOW AND SFC CAA...WILL GO MID 30S TO LOW
40S...WITH ISOLATED LOW 30S N/W. SHOULD BEGIN TO SEE THE DEVELOPMENT
OF AN OVERRUNNING SCENARIO ON MONDAY AS CANADIAN HIGH PRES SHUNTS
EWD. CLOUDS INCREASING THRU THE DAY. MAX TEMPS 45-50.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
OVERVIEW AND MODEL PREFERENCES...
MODELS CONTINUE TO STRUGGLE WITH FAST FLOW REGIME THROUGH THE MID
WEEK TIMEFRAME. WHILE THEIR REMAINS SOME AGREEMENT THAT A SFC
FRONT WILL STALL S OF THE AREA WITH SOME ISENTROPIC LIFT OVER SNE
THROUGH TUE. HOWEVER...IT IS THE APPROACH OF A COUPLE OF DIFFERENT
SHORTWAVES LATE TUE NIGHT INTO WED. ECMWF STILL SUPPORTS THESE
WAVES PHASING PRIOR TO REACHING THE REGION...HOWEVER THE GFS IS
STILL MORE PROGRESSIVE AND DOES NOT ALLOW THESE TWO WAVES TO
PHASE. THE ECMWF...WHICH DOES SHOW SOME SUPPORT FROM THE GEFS
MEAN...IS MUCH SLOWER AND MORE AMPLIFIED AS A RESULT OF THIS
PHASING. AS A RESULT...THE MOVEMENT/STRENGTH OF THE SFC LOW
SPAWNED BY THESE TWO WAVES IS STILL IN DISPUTE. THE GFS IS FASTER
AND FURTHER N AS IT APPROACHES...WHILE THE ECMWF IS SLOWER AN
FURTHER S. ATTM...WITH THE ECMWF HAVING MORE SUPPORT...WILL LEAN
FCST TOWARDS ITS SOLN BUT WILL MAINTAIN A FAIR LVL OF PERSISTENCE
IN THE FCST AS THERE ARE STILL SOME FACTORS TO BE RESOLVED. EVEN
WITH THESE DIFFERENCES EARLY ON...THE GUIDANCE SUITE IS IN GOOD
AGREEMENT THAT A SECOND ROUND OF STRONG RIDGING WILL BUILD OVER
THE ATLANTIC STATES WITH HIGH PRES INTO NEXT WEEKEND.
DETAILS...
MON NIGHT INTO TUE...
A STALLED BAROCLINIC ZONE WILL REMAIN S OF THE ARE THROUGH THIS
PERIOD. WHILE THERE IS STILL A BIT OF DISPUTE ON EXACTLY WHERE
THIS WILL END UP...IT WILL BE UNDER THE INFLUENCE OF STRONG HIGH
PRES TO THE N. THIS WILL BEGIN TO GRADUALLY SLIDE INTO THE
MARITIMES DURING THE PERIOD. GIVEN THE INCREASING MID LVL
WAA...AND AT LEAST SOME MOISTURE THROUGH THE PERIOD. FEEL THAT
OCCASIONAL -SHRA CANNOT BE RULED OUT AS LONG AS THE FRONT STAYS
PUT. HOWEVER...FEEL THAT MUCH OF THE TIME WILL BE MOSTLY DRY AND
SIMPLY CLOUDY...WHICH IS CONSISTENT WITH PREVIOUS SHIFTS FCST. H92
TEMPS GRADUALLY INCREASE TO +2C TO +6C DURING THE TIME PERIOD.
CLOUD COVER MAY NOT ALLOW THESE VALUES TO BE FULLY REACHED...SO
EVEN DURING PEAK HEATING TEMPS SHOULD NOT BE ABLE TO REACH 50F.
TUE NIGHT INTO WED...
AS MENTIONED EARLIER...THERE ARE STILL DISCREPANCIES TO BE WORKED
OUT FOR A ROBUST WAVE/SFC LOW SYSTEM THAT WILL AFFECT SNE DURING
THIS TIMEFRAME. IF THE SYSTEM LEANS MORE TOWARD THE GFS AS IT
STANDS NOW...THE SYSTEM WILL BE FULLY CLEAR OF THE AREA BY WED
EVENING. WHILE THE ECMWF IS SLOWER AND LINGERS INTO WED NIGHT. THE
PROGRESSIVE PATTERN FAVORED BY THE GFS ALSO ALLOWS THE LOW TO MOVE
N OF THE REGION...WITH MUCH OF THE FA IN THE WARM SECTOR. THE
ECMWF/GEFS MEAN REMAINS FURTHER S AND COOLER DUE TO MORE
AMPLIFICATION. GIVEN THAT THE ECMWF DOES HAVE SOME SUPPORT FROM
THE GEFS MEAN...WILL LIKELY LEAN GRIDS SLIGHTLY CLOSER TO THIS
SOLN...BUT NOT MAKE ANY DRASTIC CHANGES AS THERE ARE STILL SOME
ISSUES TO BE RESOLVED.
THE ECMWF IS COLDER TOO...THANKS TO THE MORE AMPLIFIED FLOW
PATTERN. AT PRECIP ONSET TUE NIGHT...FEEL THE WAA /H92 TEMPS
INCREASING CLOSE TO +3C TO +6C ON THE COOLER ECMWF/ IN ADVANCE OF
THE LOW WILL BE ENOUGH TO KEEP P-TYPE MOSTLY RAIN. HOWEVER...ON
WED...STRONGER LLVL ISALLOBARIC FLOW /WITH THE LOW PASSING TO THE
S/ WILL BEGIN TO DRAW COLDER AIR FROM THE N OVER THE REGION...SO
MAY SEE A TRANSITION TO SNOW FROM NW TO SE AS THE LOW PUSHES TO
THE E. BEST CHANCE FOR ACCUM WILL REMAIN IN THE HIGHER ELEVATIONS
OF THE E SLOPES OF THE BERKSHIRES/MONADNOCKS/WORCESTER HILLS.
GIVEN THE UNCERTAINTY HOWEVER...WILL REMAIN CONSERVATIVE WITH
OVERALL TOTALS.
THU INTO THE WEEKEND...
ANOTHER COOLING TREND AS COOL AIRMASS AND STRONG HIGH PRES BUILD
OVER THE REGION DURING THE DAY THU INTO THU NIGHT. WHILE THE
GRADUAL WARMING TREND MAY BE A BIT SLOWER THAN PREVIOUS WARMING
TRENDS THIS NOV...FEEL THAT TEMPS WILL LIKELY REBOUND TO
NORMAL...IF NOT EVEN SLIGHTLY ABOVE NORMAL BY SAT. DRY WX PREVAILS
UNDER HIGH PRES.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
INTO MORNING...
HIGH CONFIDENCE VFR. BKN-OVC 10 KFT CIGS WITH SCT-BKN 3-5 KFT CIGS
MAINLY FOR THE S/E TERMINALS. INFREQUENT 20-25 KT GUSTS THRU THE
INTERIOR...BETTER CHCS TERMINALS ON CAPE AND ISLANDS. LLWS OF 35
TO 45 KTS AT 2 KFT OUT OF THE SW AT 220...ESPECIALLY THRU THE
INTERIOR AND VLY LOCALES WHERE WINDS ARE LIGHTER.
TODAY...
HIGH CONFIDENCE VFR. SFC COLD FRNT APPROACHING TERMINALS ALONG AND
AHEAD OF WHICH SWLY FLOW WILL BE BLUSTERY WITH 25 KT GUSTS THRU
THE INTERIOR...30 KT GUSTS AND GREATER OVER THE CAPE AND ISLANDS.
BKN-OVC 5-10 KFT CIGS...THICKENING AND LOWERING THRU THE DAY WITH
APPROACHING COLD FRNT. MVFR CIGS PSBL LATE...BUT LOW CONFIDENCE.
TONIGHT...
MODERATE CONFIDENCE VFR. COLD FRNT SLIDE THRU THE TERMINALS EARLY.
WILL SEE WINDS LIGHTEN AND BACK OUT OF THE N/NW. COULD SEE SOME
STRONG 15-20 KT N/NW FLOW IN WAKE OF THE COLD FRNT. BKN-OVC 5-10
KFT CIGS WITH PSBL MVFR /MODERATE CONFIDENCE/ TO BECOME BKN-SCT
INTO MORNING. SLGT CHC OF SHRA THRU THE S TERMINALS.
MONDAY...
HIGH CONFIDENCE VFR. SOME LINGERING MVFR CIGS PSBL FOR S TERMINALS
BUT OTHERWISE HIGH PRES BUILDING INTO THE RGN ALLOWING CIGS TO
CLEAR. WILL SEE LGT N/NELY FLOW THRU THE TERMINALS...WITH AN
ONSHORE COMPONENT MORESO FOR THE E TERMINALS. ANTICIPATING MID-
HIGH CLOUDS TO FILTER THRU THE RGN LATE IN THE DAY.
MONDAY NIGHT...
HIGH CONFIDENCE VFR. HIGH PRES IN CONTROL. LGT AND VRB SFC WINDS.
MID-HIGH LVL CLOUDS CONTINUING TO FILTER THRU THE RGN.
KBOS TERMINAL...
HIGH CONFIDENCE VFR. SWLY WINDS GUSTING 25 TO 30 KTS THRU THE DAY
WILL SLACK AS A COLD FRNT IMPACTS THE TERMINAL DURING THE EARLY
MORNING HRS MONDAY. BKN-OVC CIGS 10 KFT INITIALLY...LOWERING WITH
APPROACHING COLD FRNT TO 5-7 KFT. WINDS BACKING OUT OF THE NW WITH
PASSAGE...AROUND 10-15 KTS PSBL IN THE IMMEDIATE WAKE.
OUTLOOK...MONDAY THROUGH THURSDAY...
TUESDAY...
VFR CONDITIONS DESPITE CLOUDS. LIGHTER EAST WINDS TUESDAY.
TUESDAY NIGHT-WEDNESDAY...
CONDITIONS GRADUALLY LOWERING WITH VFR LIKELY DIPPING ALL THE WAY
TO IFR BY LATE NIGHT. PERIODS OF RA WILL LOWER VSBYS. THIS RAIN
WILL MIX WITH SOME SNOW IN THE HIGHER TERRAIN OF NW MA AND SRN NH
ESPECIALLY LATE TUE NIGHT AND WED NIGHT. NE WINDS MAY GUST TO 35
KT OVER THE CAPE AND ISLANDS...WITH GUSTS TO 30 KT POSSIBLE OVER
THE SE COASTAL PLAIN.
THURSDAY...CONDITIONS IMPROVE TO VFR. HOWEVER GUSTY WINDS LIKELY
TO CONTINUE OUT OF THE NNW.
&&
.MARINE...
TONIGHT INTO SUNDAY...
SEAS WILL BUILD AS SW FLOW ACCELERATES OVER THE WATERS WITH GUSTS 25
TO 30 KTS. SW WINDS AT 925 MB INCREASE TO 45 TO 50 KTS LATE THIS
EVENING AND OVER THE RELATIVELY WARM OCEAN WATERS SOME OF THIS IS
EXPECTED TO MIX DOWN. AS A RESULT HAVE HOISTED A GALE WARNING FOR
ALL COASTAL WATERS EXCEPT BOSTON HARBOR AND NARRAGANSETT
BAY...STARTING LATE THIS EVENING AND RUNNING THROUGH SUNDAY.
FREQUENT GUSTS TO 35 KTS ARE EXPECTED...EXCEPT GUSTS TO 30 KTS
BOSTON HARBOR AND NARRAGANSETT BAY.
OPTED TO CONTINUE TO GO HIGHER THAN WNAWAVE GUIDANCE FOR BUZZARDS
BAY...VINEYARD SOUND AND NANTUCKET SOUND BASED ON OBSERVATIONS FROM
THIS AFTERNOON. MAIN CONCERN WILL BE PERIODS WHEN OUTGOING TIDE
COINCIDES WITH THE STRONG SW WINDS FOR BUZZARDS BAY AND VINEYARD
SOUND...CREATING ROUGH SEAS AND STEEP WAVES. THIS PROMPTED
FORECAST SEAS OF 4 TO 7 FEET FOR THOSE MARINE ZONES FOR TONIGHT
INTO SUNDAY.
SUNDAY NIGHT INTO MONDAY... WIND GUSTS GENERALLY DIMINISHING BELOW
25 KTS LATE SUNDAY NIGHT INTO EARLY MONDAY MORNING...THOUGH DURING
MONDAY A FEW GUSTS TO 25 KTS MAY OCCUR ON THE OUTER COASTAL WATERS.
SEAS WILL STILL REMAIN CHOPPY ON THE OUTER COASTAL WATERS WITH 5 TO
7 FOOT SEAS.
OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...
MON NIGHT INTO TUE...
WINDS AND SEAS GENERALLY REMAIN BELOW SCA. HIGH PRES DOMINATING
OVER THE WATERS.
TUE NIGHT INTO WED NIGHT...
LOW PRES MOVING IN FROM THE OH VALLEY. WINDS AND SEAS GRADUALLY
INCREASING. GALES POSSIBLE ESPECIALLY DURING THE DAY WED INTO WED
NIGHT. OTHERWISE SCA/S WILL BE NEEDED.
THU...
WINDS GRADUALLY DROP TO SCA DURING THE DAY. SCA LIKELY NEEDED FOR
BOTH WINDS AND SEAS.
&&
.TIDES/COASTAL FLOODING...
STRONG EAST TO NORTHEAST WINDS EXPECTED WEDNESDAY IN ADVANCE OF
DEVELOPING LOW PRESSURE THAT SHOULD PASS SOUTH OF NEW ENGLAND.
SURFACE PRESSURE FALLS OF 1 TO 2 MB PER HOUR AND WINDS AT 925 MB
OF 30 TO 40 KNOTS ARE FORECAST. WAVE MODELS ARE FORECASTING 10 TO
12 FOOT SEAS EAST OF CAPE COD AND STELLWAGEN BANK. MEANWHILE
ASTRONOMICAL TIDES AT BOSTON ARE EXPECTED TO BE HIGH WITH A PEAK
ASTRO TIDE OF 11.6 FEET WEDNESDAY MORNING AND 12.0 FEET
THANKSGIVING MORNING.
THIS SCENARIO BEARS WATCHING FOR POTENTIAL BEACH EROSION AND MINOR
COASTAL FLOODING...ESPECIALLY ALONG THE EASTERN MASSACHUSETTS
COAST.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ231>235-237-
250-251-254>256.
SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ230-
236.
&&
$$
SYNOPSIS...DOODY/NMB
NEAR TERM...SIPPRELL
SHORT TERM...NMB
LONG TERM...DOODY
AVIATION...DOODY/SIPPRELL
MARINE...DOODY/NMB
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
228 AM CST SUN NOV 20 2011
.SYNOPSIS...
WATER VAPOR LOOP AND RUC ANALYSIS AS OF 20/07Z SHOWED AN EXITING
UPPER TROPOSPHERIC JET STREAK CENTERED FROM SOUTH DAKOTA THROUGH
NORTHERN WISCONSIN. A SUBTROPICAL JET EXTENDED FROM CENTRAL BAJA
CALIFORNIA NORTHEAST INTO WEST TEXAS...WHICH WAS RESPONSIBLE FOR A
LARGE AREA OF CIRRIFORM CLOUD COVER OVER MUCH OF THE CENTRAL PLAINS
SOUTHWEST INTO WEST TEXAS. FARTHER WEST...AN UPPER LOW CONTINUED TO
DIG SOUTH JUST OFF THE COAST OF NORTHERN CALIFORNIA. AT THE
SURFACE...THE STRONG COLD FRONT WHICH PROVIDED KANSAS WITH THE
COLDEST AIRMASS OF THE YOUNG COLD SEASON WAS MOVING INTO NORTHWEST
TEXAS...AND EXTENDED NORTHEAST INTO NORTHWEST ARKANSAS. THE CENTER
OF THE ARCTIC HIGH WAS STILL POSITIONED OVER THE NORTHERN PLAINS
WHERE TEMPERATURES IN THE CORE OF THE ARCTIC AIRMASS IN THE WESTERN
DAKOTAS AND EASTERN MONTANA WERE ANYWHERE FROM 0F TO -10F. A
COMPARISON OF THE 06Z OBS WITH THE 6-HR FORECAST FROM THE NAM12
SHOWS A WIDESPREAD 4 TO 7 DEGREE WARM BIAS IN THE MODEL 2M
TEMPERATURES IN THE ARCTIC AIRMASS FROM CENTRAL NEBRASKA INTO THE
DAKOTAS. AHEAD OF THE FRONT IN TEXAS...ANOMALOUS MOISTURE RETURN WAS
UNDERWAY WITH 70F DEWPOINTS REACHING AS FAR NORTH AS A WACO TO
TYLER, TEXAS LINE. -UMSCHEID
&&
.DISCUSSION...
DAYS 1-2 /TODAY THROUGH MONDAY NIGHT/...
TODAY:
INHERITED FORECAST HIGHS (UPPER 30S NORTHEAST HALF TO THE LOWER 40S
SOUTHWEST) FOR TODAY LOOK PRETTY GOOD AND SEE NO REASON TO ADJUST AS
THEY ARE ALREADY A FEW DEGREES COLDER THAN THE GUIDANCE AND GRIDDED
2M TEMPS. WINDS SHOULD BE RATHER LIGHT AS THE SURFACE RIDGE AXIS
MOVES ACROSS KANSAS TODAY. WINDS WILL EVENTUALLY SHIFT TO THE EAST
BY LATE IN THE DAY WITH THE RIDGE AXIS WEAKENING AND MOVING TO THE
EAST. THE NAM12 STILL SHOWS A SIGNAL OF DEVELOPING A NARROW BAND OF
STRATUS AND EVEN PERHAPS SOME LIGHT FREEZING DRIZZLE WITHIN THE BAND
OF DEFORMATION/THERMAL GRADIENT IN THE 850-800MB LAYER OVER THE
SOUTHEASTERN ZONES. WILL KEEP A MENTION OF PATCHY FREEZING
DRIZZLE...BUT CONFINE IT TO THE FAR SOUTHEAST...MAINLY COMANCHE AND
BARBER COUNTIES.
TONIGHT:
THE UPPER LOW OFF THE COAST OF CALIFORNIA WILL HAVE MOVED SOUTHEAST
TO CALIFORNIA/BAJA CALIFORNIA BORDER AREA BY LATE TONIGHT. WILL
START TO SEE A RESPONSE ACROSS WEST AND SOUTHWEST TEXAS WITH
INCREASING WINDS OFF THE SURFACE AND LOW LEVEL MOISTURE (+10 TO +12C
850MB DEWPOINT) MAKING A RUN ON THE TEXAS PANHANDLE BY THE END OF
THIS PERIOD. A WEAK SURFACE LOW WILL DEVELOP ALONG THE STALLED OUT
FRONT OVER SOUTHEASTERN NEW MEXICO AND ADJACENT SOUTHWEST TEXAS WITH
STRONG 850MB FLOW ABOVE THE SHALLOW COLD AIRMASS RESULTING IN
STRATUS DEVELOPMENT INTO THE TEXAS PANHANDLE BY 12Z MONDAY. DESPITE
THE WEAK WINDS AT THE SURFACE...LOWS SHOULD NOT GET MUCH BELOW
22-25F RANGE WITH SOME HIGH CLOUD COVER TIED TO THE SOUTHERN BRANCH
JET LINGERING AROUND WESTERN KANSAS.
MONDAY:
A FAIRLY ROBUST POTENTIAL VORTICITY ANOMALY WILL BE ROUNDING THE
BASE OF THE TROUGH AND EJECT NORTHEASTWARD OUT INTO EASTERN NEW
MEXICO AND WEST TEXAS. THIS IS USUALLY A FAVORABLE TRACK FOR HEAVY
PRECIPITATION ACROSS PORTIONS OF THE DDC FA. WARM FRONTOGENESIS
WILL INCREASE ACROSS THE TEXAS PANHANDLE WITH SHOWERS AND
THUNDERSTORMS BLOSSOMING BY EARLY AFTERNOON. THE RAIN AND
THUNDERSTORM ACTIVITY WILL LIFT NORTHEAST DURING THE AFTERNOON HOURS
AND IMPINGE OF THE SOUTHERN/SOUTHEASTER DDC FA BY THE END OF THIS
PERIOD. TEMPERATURES ARE EXPECTED TO WARM INTO THE UPPER 30S TO
LOWER 40S IN THE SOUTHEASTERN PORTION OF THE FORECAST AREA SO AM
EXPECTING PRECIPITATION TYPE TO BE ALL RAIN. POPS WILL BE 30 TO 40
PERCENT IN THE FAR SOUTHEAST DDC FA WITH 20 POPS OVER THE REST OF
THE SOUTHERN THROUGH EAST-CENTRAL ZONES.
MONDAY NIGHT:
TYPICALLY...THE TRACK OF SUCH A FORMIDABLE AND COMPACT STORM SYSTEM
FROM EASTERN NEW MEXICO TO NORTHWEST OKLAHOMA IS FAVORABLE FOR HEAVY
PRECIPITATION ACROSS AT LEAST A PORTION OF THE DDC FORECAST AREA.
THERE WILL BE TWO PROBLEMS THAT WILL MITIGATE HEAVY PRECIPITATION
POTENTIAL FOR A LARGER AREA OF SOUTHWEST KANSAS. 1) 700-500MB MEAN
FLOW FROM ABOUT 230 DEGREES MEANS THAT HEAVY RAIN AND THUNDERSTORM
ACTIVITY THAT FORMS IN THE WARM/MOIST CONVEYOR OVER THE TX PANHANDLE
WILL THEN MOVE INTO FAR NORTHEASTERN TEXAS PANHANDLE/NORTHWEST
OKLAHOMA...THEN INTO SOUTH-CENTRAL KANSAS...CLIPPING THE DDC
FORECAST AREA. 2) LATE DEVELOPMENT OF THE 700MB LOW. MODELS SHOW
THE 700MB LOW DEVELOPING AND MATURING EARLY TUESDAY MORNING OVER
SOUTH CENTRAL KANSAS...SUCH THAT ONCE A "WRAP AROUND" COLD CONVEYOR
CAN DEVELOP AND BECOME ESTABLISHED...IT WILL DO SO JUST EAST OF THE
DDC FA. FOR THESE REASONS...AREAS ALONG AND NORTHWEST OF A LIBERAL
TO DODGE CITY TO LARNED LINE STAND TO SEE A VERY LOW POTENTIAL FOR
BENEFICIAL PRECIPITATION (LESS THAN A TENTH OF AN INCH). FAR
SOUTHEAST DDC FA (I.E. KIOWA IN BARBER COUNTY) COULD SEE OVER
THREE-QUARTERS OF AN INCH BY EARLY TUESDAY MORNING. -UMSCHEID
DAYS 3-7 /TUESDAY THROUGH SATURDAY NIGHT/...
THE PERIOD WILL BEGIN WITH INCREASING UPPER LEVEL RIDGING AND
ISENTROPIC DOWNGLIDE DEVELOPING. NORTHWEST SURFACE WINDS WILL
PROBABLY BE ON THE BREEZY SIDE TUESDAY AS SURFACE PRESSURE INCREASES
ACROSS WESTERN KANSAS AS A LARGE SURFACE ANTICYCLONE SHIFTS EASTWARD
FROM SOUTHEAST KANSAS THROUGH THE MID MISSISSIPPI VALLEY. THESE WINDS
WILL DIMINISH TO LIGHT THROUGH TUESDAY NIGHT AND EARLY WEDNESDAY,
BACKING TO THE SOUTHWEST AGAIN AND BECOMING LIGHT SOUTHWEST THROUGH
THE DAY ON WEDNESDAY. THIS TRANSITION SHOULD SUPPORT WARMING
TEMPERATURES FROM THE 50S ON TUESDAY BACK UP TO AROUND 60 OR MORE ON
WEDNESDAY WITH SOUTHERLY FLOW AND WARM AIR ADVECTION/DOWNSLOPE.
THE UPPER PATTERN WILL REMAIN IN A PROGRESSIVE TROUGH - RIDGE -
TROUGH PATTERN THROUGH THE WEEK. FROM WEDNESDAY NIGHT INTO EARLY
FRIDAY, THE MODELS SWING ANOTHER UPPER JET SEGMENT FROM THE SOUTHERN
ROCKIES INTO THE CENTRAL PLAINS. AS A RESULT, ANOTHER DECENT SURFACE
TROUGH WILL DEVELOP OVER THE CENTRAL HIGH PLAINS ON THURSDAY WHICH
WILL PRODUCE BREEZY TO WINDY SOUTHWEST WINDS AGAIN, BETTER MIXING
AND EVEN WARMER TEMPERATURES INTO THE 60S. AS THE UPPER PATTERN
CONTINUES TO EVOLVE INTO A SHARPER TROUGH OVER THE CENTRAL PLAINS,
ANOTHER STRONG COLD FRONT WILL SWEEP INTO THE HIGH PLAINS FROM
MONTANA AND WYOMING, BRINGING STRONG NORTHWEST WINDS AND COLD
ADVECTION FRIDAY OR FRIDAY NIGHT FOLLOWED BY A COOLING TREND INTO
SUNDAY. -RUSSELL
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 39 23 49 32 / 0 0 20 30
GCK 40 22 49 31 / 0 0 10 20
EHA 46 29 52 34 / 0 0 10 20
LBL 44 26 52 33 / 0 0 10 30
HYS 39 20 49 31 / 0 0 10 20
P28 40 26 50 36 / 10 0 40 80
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN25/33
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1237 AM EST SUN NOV 20 2011
.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFFSHORE THIS WEEKEND AND INTO EARLY NEXT
WEEK. TEMPERATURES WILL BEGIN TO WARM OVER THE WEEKEND AS SOUTHERLY
WINDS DEVELOP. A COLD FRONT WILL MOVE THROUGH WEDNESDAY. COOLER
WEATHER IS EXPECTED LATE NEXT WEEK AS HIGH PRESSURE BUILDS IN.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 10 PM SATURDAY...LIGHT EASTERLY/ONSHORE FLOW HAS
DEVELOPED AS SURFACE RIDGE AXIS MOVES OFFSHORE...BRINGING
TEMPERATURES ALONG THE COAST UP A TAD...IN THE LOWER TO MID 60S
MANY LOCATIONS. WILL LOOK AT MODIFYING THE TEMPERATURE CURVE IF
NEED BE TO ACCOUNT FOR THIS. OTHERWISE...FORECAST REMAINS ON
TRACK. PREVIOUS DISCUSSIONS FOLLOW:
QUITE A DIFFERENCE FROM 24 HOURS AGO. RADIATIONAL COOLING
CONDITIONS NOT NEARLY AS FAVORABLE...WITH PATCHES OF STRATO-CU
BLANKETING THE AREA AND MOISTER LOWER LEVELS THAN THIS TIME
YESTERDAY. TEMPERATURES HAVE BEEN SLOWER TO FALL AND RANGE FROM
THE 50S INLAND TO AROUND 60 AT THE COAST. AS DESCRIBED IN PREVIOUS
DISCUSSION BELOW...EXPECT A RELATIVELY MILD NIGHT. WILL LIKELY SEE
FOG DEVELOP OVERNIGHT MOST LOCATIONS.
SURFACE TROUGH REMAINING JUST TO THE EAST OF LOCAL COASTAL WATERS
WILL SHIFT FARTHER WEST CLOSER TO THE CAROLINA COAST THROUGH THIS
EVENING BEFORE DISSIPATING OVERNIGHT. LIGHT NORTHEAST FLOW ON WEST
SIDE OF TROUGH WILL SHIFT MORE EASTERLY ESPECIALLY ALONG THE COAST
AS IT SHIFTS CLOSER. OVERALL WEAK GRADIENT WITH WINDS REMAINING 5
MPH OR LESS MOST PLACES AT THE SURFACE. RUC SOUNDINGS SHOWING AN
OVERALL WARMING AND DRYING OF THE COLUMN AT LOW LEVELS AS WARMER
AIR MAKES ITS WAY IN ALOFT AND MIXING OCCURS THROUGH TODAY...BUT
DECENT ON SHORE SE FLOW AT H85 CONTINUING TO BRING MOISTURE AND
SOME CLOUDS ON SHORE MAINLY OVER SC.
ON SHORE FLOW WILL CAPTURE SOME OF THE MARINE INFLUENCE CONTINUING
TO BRING HIGHER DEWPOINT AIR INLAND AS WINDS SHIFT BECOMING MORE
EASTERLY. THE DEWPOINTS ALONG THE COAST WILL REMAIN IN THE 50S
THROUGH MOST OF THE NIGHT WHILE INLAND DEWPOINTS WILL BE IN THE
MID 40S. WAA WILL CONTINUE WITH SW FLOW ABOVE THE SURFACE. 850
TEMPS AROUND 4 TO 5 C THIS MORNING WILL RISE UP TO AROUND 8C BY
DAYBREAK ON SUNDAY. LOW LEVEL FLOW WILL CONTINUE TO COME AROUND
FROM S-SE TO SW OVERNIGHT WHILE SURFACE WINDS BECOME VERY LIGHT
AND VARIABLE TO NEAR CALM. CLOUDS ASSOCIATED WITH COASTAL TROUGH
MAY MOVE ON SHORE THROUGH THIS EVENING AS H85 FLOW CONTINUES OUT
OF THE SE BEFORE SHIFTING TO S-SW OVERNIGHT. THE SFC TROUGH AXIS
SHIFTS A LITTLE FARTHER WEST BUT DISSIPATES OVERNIGHT AS HIGH
PRESSURE CONTINUES TO RIDGE BACK INTO THE CAROLINAS. OVERALL VERY
WEAK PRESSURE PATTERN EXPECTED WITH CALM WINDS. FOR NOW WILL KEEP
MOST CLOUDS OUT OF THE EQUATION ALLOWING FOR MORE IDEAL
RADIATIONAL COOLING AND DENSER FOG THREAT...BUT THE EXTENT OF FOG
WILL DEPEND ON HOW MUCH CLOUD COVER THERE WILL BE...WHICH WILL BE
THE FORECAST CHALLENGE OVERNIGHT.
TEMPS WILL DROP OFF AS WE RADIATE OUT OVER MOST PLACES BUT
WAA...INCREASED LOW LEVEL MOISTURE AND SOME CLOUDS WILL KEEP TEMPS
AND SFC DEWPOINTS HIGHER THAN PREVIOUS NIGHTS. FORECAST LOWS WILL
THEREFORE DROP TO THE LOW TO MID 40S MOST PLACES INLAND AND CLOSER
TO 50 ALONG THE COAST.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...HIGH PRESSURE WILL SHIFT OFF THE COAST SUNDAY
AND RESULT IN WARMING S-SW FLOW THROUGH THE PERIOD. THERE WILL BE
SOME INCREASE IN CLOUDS MONDAY NIGHT AS A FRONTAL SYSTEM APPROACHES
FROM THE WEST...OTHERWISE FAIR WEATHER IS EXPECTED. HIGHS WILL
MODERATE SLIGHTLY EACH DAY...MODERATING FROM THE LOWER 70S SUNDAY TO
THE MIDDLE 70S MONDAY. LOWS SUNDAY NIGHT WILL FALL TO THE UPPER 40S
TO LOWER 50S WITH MID TO UPPER 50S EXPECTED MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 300 PM SATURDAY...DAYBREAK TUESDAY AN UPPER TROUGH AXIS WILL
BE POSITIONED ROUGHLY ALONG THE MISSISSIPPI VALLEY...WITH SURFACE
HIGH PRESSURE SITUATED OFFSHORE OF THE CAROLINAS. EARLY TUESDAY A
WARM FRONT WILL RESIDE NORTH OF THE AREA...SO NO MENTIONABLE POP
VALUES PLANNED UNTIL TUESDAY NIGHT AS A COLD FRONT BREAKS EAST OF
THE APPALACHIAN MOUNTAINS. FRONTAL PASSAGE BASED ON AN GFS/ECMWF
CONSENSUS SOMETIME WEDNESDAY EITHER SIDE OF MIDDAY. SHRA TAPERING
OFF AND COLD AIR ADVECTION REGIME WEDNESDAY NIGHT AND A CLEARING
TREND INTO EARLY THURSDAY.
HENCE A DRY FORECAST DAY 6/7 FRI/SAT ALTHOUGH WE MAY EXPECT RETURN
FLOW NEXT WEEKEND AS THE PATTERN SHOWS A PROGRESSIVE NATURE.
TEMPERATURES 7-10 DEG F ABOVE NORMAL TUE/WED IN WARM SECTOR OF THE
APPROACHING FRONT...KNOCKED DOWN TO NORMAL DIURNAL TEMPERATURE
CURVES FOR NOVEMBER THU/FRI...THEN WARMING INTO NEXT SATURDAY.
THANKSGIVING DAY LOOKS SUNNY AND COOL. THE COLDEST MORNING IN THE
EXTENDED FORECAST LOOKS TO BE FRIDAY MORNING AS THE HIGH SETTLES
OVERHEAD BENEATH A CLEAR DOME...SO FREEZING TEMPS POSSIBLE THEN.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 06Z...LATEST 11U-3.9U MICRON SATELLITE IMAGERY IS DETECTING
SCATTERED TO BROKEN LOW/MID-LEVEL CLOUDS ALONG AND WEST OF I-95
...AND LOW/MID LEVEL CLOUDS OFFSHORE FROM THE CAROLINAS.
MVFR VISIBILITIES IN BR HAVE DEVELOPED ACROSS THE MAJORITY OF THE
TERMINALS...IE. FLO/LBT/MYR.
FORECAST SOUNDINGS ARE INDICATING CLOUDS WILL SCATTER OVER THE NEXT
SEVERAL HOURS ALONG AND WEST OF I-95...LEAVING SCT OR SKC FOR SKY
CONDITIONS. WITH NEARLY CLEAR SKIES AND CALM WINDS THROUGH
SUNRISE...THE FOG WILL ULTIMATELY WORSEN...REACHING OCCASIONALLY THE
DENSE CRITERIA. HAVE INCLUDED AT ALL SITES...THIS INCREASED FOG
POTENTIAL PLACING IT AS THE PREDOMINATE VSBY ACROSS THE COASTAL
SITES. WILL ONLY INDICATE TEMPO MVFR VISIBILITIES AT ALL SITES FROM
ANY REMAINING CLOUDS...IE. 3.5 KFT OR HIGHER.
EXPECT COASTAL TERMINALS TO BECOME VFR 12-14Z AND THE FLO/LBT
13-15Z. VFR EXPECTED THE REMAINDER OF THE DAY THROUGH THE EVENING
HOURS WITH VARIABLE WINDS IN THE AM HRS...BECOMING LIGHT SOUTH TO
SOUTHWEST BY MIDDAY AND CONTINUING INTO THE EVENING HRS.
EXTENDED OUTLOOK...LOW CONFIDENCE IN FOG MONDAY/TUESDAY MORNINGS AND
ISOLATED SHOWERS DURING THE AFTERNOONS. SHOWERS ASSOCIATED WITH A
COLD FRONT MAY IMPACT THE TERMINALS ON WEDNESDAY. VFR THURSDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10 PM SATURDAY...NO CHANGES TO THE FORECAST OR CONDITIONS
OVER THE COASTAL WATERS SINCE LAST UPDATE. LIGHT EASTERLY FLOW
WITH SEAS IN THE 2 TO 3 FT RANGE PREVAIL. PREVIOUS DISCUSSIONS
FOLLOW:
LATEST OBS SHOW SEAS IN THE 2 TO 3 FT RANGE WITH A LIGHT EASTERLY
WIND. WINDS WILL BECOME MORE VARIABLE AS SURFACE RIDGE AXIS MOVES
OVERHEAD...OTHERWISE EXPECT LITTLE CHANGE IN SEA HEIGHT OVERNIGHT.
PREVIOUS DISCUSSION FOLLOWS:
WINDS WILL SHIFT AROUND TO THE E-SE THROUGH THIS EVENING AS TROUGH
JUST TO THE EAST OF LOCAL WATERS SHIFTS A LITTLE FARTHER WEST
THROUGH THIS EVENING BEFORE DISSIPATING BY DAYBREAK. OVERALL WEAK
HIGH PRESSURE WILL CONTINUE TO RIDGE INTO THE CAROLINAS AS IT
SHIFTS FARTHER OFF SHORE OVERNIGHT. THEREFORE EXPECT SFC WINDS TO
BECOME LIGHT WEST OR VARIABLE OVERNIGHT AROUND 5 TO 10 KTS. PATCHY
CU MAY CONTINUE TO MOVE OVER THE LOCAL WATERS OR DEVELOP ALONG THE
SFC TROUGH. CAN NOT RULE OUT A SPRINKLE AS TROUGH MOVES SLIGHTLY
CLOSER TO THE COAST THIS EVENING BEFORE WEAKENING. SLIGHTLY LONGER
PERIOD E-NE SWELL COMING AROUND THE HIGH PRESSURE WILL COMBINE
WITH LOCALLY MINIMAL WIND WAVE TO PRODUCE SEAS IN THE 2 TO 3 FT
RANGE MOST WATERS WITH A FEW 4 FOOTERS IN OUTER WATERS.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 3 PM SATURDAY...LIGHT AND VARIABLE WINDS SUNDAY WILL BECOME S
TO SW DURING THE AFTERNOON AND CONTINUE THROUGH MONDAY NIGHT.
SPEEDS OF 15 KT OR LESS ARE EXPECTED THROUGH THE PERIOD WITH SEAS
WILL OF 2 TO 4 FT.
LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 300 PM SATURDAY...TUESDAY THROUGH THURSDAY LOOKS UNSETTLED
AND ROUGH ON THE 0-20NM WATERS...PRIMARILY DUE TO A COLD FRONTAL
PASSAGE WEDNESDAY. PRE-FRONT SW WINDS LATE TUESDAY...AND POST-
FRONT NW WINDS LATE WED MAY BOTH REQUIRE AN ADVISORY...HENCE WE
MAY SEE AN ADVISORY FROM TUESDAY NIGHT THROUGH WEDNESDAY NIGHT
BASED ON CURRENT TIMING AND STRENGTH OF THE APPROACHING FRONT.
ADDITIONALLY...WE MAY SEE A FEW TSTMS OVER THE WATERS WEDNESDAY.
THE SEA SPECTRUM TUE-THU WILL BE MARKED BY E WAVES 2-3 FEET AT 10
SECONDS...WITH GROWING SSW WIND-WAVES/BUILDING SOUTHERLY CHOP AND
SLOP. EXPECT A WIND-SHIFT TO NW WED AFTERNOON...CHANGING DIRECTION
OF THE SHORT PERIOD WAVES. THE COLD AIR ADVECTION BEHIND THE FRONT
WILL BRING NW WIND GUSTS TO 25-30 KNOTS WEDNESDAY AFTERNOON AND
NIGHT. THURSDAY OR THANKSGIVING DAY...A DAY OF IMPROVEMENT BUT A
BIT ROUGH IN THE MORNING FROM NNW WINDS...HIGHEST OFFSHORE. NEAR
SHORE CONDITIONS WILL IMPROVE THE QUICKEST EARLY THURSDAY.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...REK
NEAR TERM...REK/RGZ
SHORT TERM...RAN
LONG TERM...MJC
AVIATION...DCH/MRR
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
920 AM EST SUN NOV 20 2011
.UPDATE...DEEP LAYER RIDGING IS LOCATED JUST OFF THE NE FL COAST
ACCORDING TO LATEST RUC ANALYSIS. SFC RIDGE IS ACROSS ERN GA/SC
AND INTO THE WRN ATLC WITH WEAK ONSHORE FLOW PER MSAS ANALYSIS.
WEAK INVERTED TROUGHING NOTED NEAR THE COAST. SKIES ARE MOSTLY
CLEAR TO PARTLY CLOUDY WITH MOSTLY CLOUDY CONDS JUST TO THE W OF
THE AREA IN ASSOCIATION WITH A WEAK SHORTWAVE TROUGH BUT NO
OBVIOUS SFC REFLECTION NOTED WITH THIS FEATURE. SFC OBS IN THE
AREA SHOW PATCHY DENSE FOG HAS DISSIPATED.
FCST FOR REST OF TODAY...WEAK SFC RIDGE REMAINS N OF THE AREA AND
LLVL WINDS REMAIN E TO SE AROUND 5-10 MPH UP TO 15 MPH. WITH
PARTLY SUNNY SKIES AND WARM ADVECTION TEMPS WILL RISE TO UPPER 70S
TO THE LOWER 80S...WITH SLIGHTLY COOLER CONDS IN MID 70S NEAR THE COAST.
THE WEAK SHORTWAVE TROUGH WILL CONT TO PRESS EWD WITH A FAIRLY
NARROW RIBBON OF MOISTURE ORIENTED SW-NE PUSHING INTO THE SE GA
ZONES. RADAR SHOWS ASSOCD SHOWER ACTIVITY WITH THE SHORTWAVE IS
LIGHT AND EXPECT THIS TO PERSIST AND THUS KEEPING ONLY 20% POPS FOR
SE GA TODAY...PERHAPS REACHING INTO A SMALL PART OF SUWANNEE
VALLEY AREA.
TONIGHT...AREAS OF FOG EXPECTED TO DEVELOP AFTER MIDNIGHT WITH A
GOOD CHANCE OF DENSE FOG FORMING BY EARLY MORNING GIVEN SFC WINDS
BECOMING NEAR CALM AND MORE THAN SUFFICIENT BOUNDARY LAYER
MOISTURE. CURRENT FCST HANDLES THIS WELL.
&&
.AVIATION...SCT-BKN CU EXPECTED TODAY WITH POSSIBLE MVFR CIGS NEAR
3 KFT. MAIN ISSUE NEXT 24 HRS WILL BE LATE TONIGHT FOG WITH MVFR BR
POSSIBLE BY 03Z-05Z THEN VLIFR PROGGED AFTER 06Z.
&&
.MARINE...WINDS ARE ELY AROUND 10-15 KT AND SEAS UP TO 3-5 FT. MAY
BE SOME 5-6 FT SEAS OVER OFFSHORE WATERS SO WILL KEEP SCEC
OFFSHORE HEADLINE IN PLACE. MOST OF WAVE ENERGY IS IN THE SWELL
PORTION WITH PERIODS OF 7-9 SECONDS AND WILL INDICATE IN UPDATED
CWF. MAIN IMPACT IN NEXT 24 HRS WILL BE DENSE FOG THAT WILL BE
LIKELY ALONG THE COAST EARLY MONDAY MORNING.
RIP CURRENTS: STILL HAZARDOUS SURF AT TIMES TODAY DUE TO THE SWELL
ENERGY COMING INTO THE SURF ZONE AND SANDBARS CREATED FROM PRIOR
DAYS SURF CONDITIONS. MODERATE RISK OF RIP CURRENTS TODAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 78 56 81 57 / 20 20 10 10
SSI 75 61 77 61 / 10 10 10 10
JAX 79 59 80 59 / 10 10 10 0
SGJ 78 63 77 62 / 10 10 10 0
GNV 82 59 82 57 / 10 10 10 0
OCF 83 60 83 59 / 10 10 10 0
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...NONE.
&&
$$
SHASHY/MCALLISTER
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
539 AM CST SUN NOV 20 2011
.UPDATE...
.AVIATION /FOR THE 12Z TAF ISSUANCE/
LOW LIFR/IFR STRATUS WILL BE A FORECAST CHALLENGE OVER THE NEXT
SEVERAL HOURS. A CORRIDOR OF IFR STRATUS HAS FORMED ACROSS CENTRAL
KANSAS EXTENDING THROUGH HYS AND DDC. GIVEN THE VERY WEAK UPSLOPE
SURFACE WIND COMPONENT AND EASTERLY FLOW IN THE LOWEST
GATES ON THE HAVILAND, KS PROFILER, WE ARE PESSIMISTIC THAT THIS
STRATUS WILL VERY QUICKLY DISSIPATE THIS MORNING. AT THIS TIME, WE
WILL CARRY PREVAILING IFR STRATUS IN THE TERMINALS THROUGH AT LEAST
16 UTC BEFORE ALLOWING ANY IMPROVEMENT TO CEILINGS. SURFACE WINDS
WILL REMAIN LIGHT AND VEERING WITH TIME THROUGH THE DAY IN RESPONSE
TO THE EASTWARD DRIFTING NORTHERN PLAINS ANTICYCLONE. - RUSSELL
&&
.PREV DISCUSSION... /ISSUED 228 AM CST SUN NOV 20 2011/
SYNOPSIS...
WATER VAPOR LOOP AND RUC ANALYSIS AS OF 20/07Z SHOWED AN EXITING
UPPER TROPOSPHERIC JET STREAK CENTERED FROM SOUTH DAKOTA THROUGH
NORTHERN WISCONSIN. A SUBTROPICAL JET EXTENDED FROM CENTRAL BAJA
CALIFORNIA NORTHEAST INTO WEST TEXAS...WHICH WAS RESPONSIBLE FOR A
LARGE AREA OF CIRRIFORM CLOUD COVER OVER MUCH OF THE CENTRAL PLAINS
SOUTHWEST INTO WEST TEXAS. FARTHER WEST...AN UPPER LOW CONTINUED TO
DIG SOUTH JUST OFF THE COAST OF NORTHERN CALIFORNIA. AT THE
SURFACE...THE STRONG COLD FRONT WHICH PROVIDED KANSAS WITH THE
COLDEST AIRMASS OF THE YOUNG COLD SEASON WAS MOVING INTO NORTHWEST
TEXAS...AND EXTENDED NORTHEAST INTO NORTHWEST ARKANSAS. THE CENTER
OF THE ARCTIC HIGH WAS STILL POSITIONED OVER THE NORTHERN PLAINS
WHERE TEMPERATURES IN THE CORE OF THE ARCTIC AIRMASS IN THE WESTERN
DAKOTAS AND EASTERN MONTANA WERE ANYWHERE FROM 0F TO -10F. A
COMPARISON OF THE 06Z OBS WITH THE 6-HR FORECAST FROM THE NAM12
SHOWS A WIDESPREAD 4 TO 7 DEGREE WARM BIAS IN THE MODEL 2M
TEMPERATURES IN THE ARCTIC AIRMASS FROM CENTRAL NEBRASKA INTO THE
DAKOTAS. AHEAD OF THE FRONT IN TEXAS...ANOMALOUS MOISTURE RETURN WAS
UNDERWAY WITH 70F DEWPOINTS REACHING AS FAR NORTH AS A WACO TO
TYLER, TEXAS LINE. -UMSCHEID
DISCUSSION...
DAYS 1-2 /TODAY THROUGH MONDAY NIGHT/...
TODAY:
INHERITED FORECAST HIGHS (UPPER 30S NORTHEAST HALF TO THE LOWER 40S
SOUTHWEST) FOR TODAY LOOK PRETTY GOOD AND SEE NO REASON TO ADJUST AS
THEY ARE ALREADY A FEW DEGREES COLDER THAN THE GUIDANCE AND GRIDDED
2M TEMPS. WINDS SHOULD BE RATHER LIGHT AS THE SURFACE RIDGE AXIS
MOVES ACROSS KANSAS TODAY. WINDS WILL EVENTUALLY SHIFT TO THE EAST
BY LATE IN THE DAY WITH THE RIDGE AXIS WEAKENING AND MOVING TO THE
EAST. THE NAM12 STILL SHOWS A SIGNAL OF DEVELOPING A NARROW BAND OF
STRATUS AND EVEN PERHAPS SOME LIGHT FREEZING DRIZZLE WITHIN THE BAND
OF DEFORMATION/THERMAL GRADIENT IN THE 850-800MB LAYER OVER THE
SOUTHEASTERN ZONES. WILL KEEP A MENTION OF PATCHY FREEZING
DRIZZLE...BUT CONFINE IT TO THE FAR SOUTHEAST...MAINLY COMANCHE AND
BARBER COUNTIES.
TONIGHT:
THE UPPER LOW OFF THE COAST OF CALIFORNIA WILL HAVE MOVED SOUTHEAST
TO CALIFORNIA/BAJA CALIFORNIA BORDER AREA BY LATE TONIGHT. WILL
START TO SEE A RESPONSE ACROSS WEST AND SOUTHWEST TEXAS WITH
INCREASING WINDS OFF THE SURFACE AND LOW LEVEL MOISTURE (+10 TO +12C
850MB DEWPOINT) MAKING A RUN ON THE TEXAS PANHANDLE BY THE END OF
THIS PERIOD. A WEAK SURFACE LOW WILL DEVELOP ALONG THE STALLED OUT
FRONT OVER SOUTHEASTERN NEW MEXICO AND ADJACENT SOUTHWEST TEXAS WITH
STRONG 850MB FLOW ABOVE THE SHALLOW COLD AIRMASS RESULTING IN
STRATUS DEVELOPMENT INTO THE TEXAS PANHANDLE BY 12Z MONDAY. DESPITE
THE WEAK WINDS AT THE SURFACE...LOWS SHOULD NOT GET MUCH BELOW
22-25F RANGE WITH SOME HIGH CLOUD COVER TIED TO THE SOUTHERN BRANCH
JET LINGERING AROUND WESTERN KANSAS.
MONDAY:
A FAIRLY ROBUST POTENTIAL VORTICITY ANOMALY WILL BE ROUNDING THE
BASE OF THE TROUGH AND EJECT NORTHEASTWARD OUT INTO EASTERN NEW
MEXICO AND WEST TEXAS. THIS IS USUALLY A FAVORABLE TRACK FOR HEAVY
PRECIPITATION ACROSS PORTIONS OF THE DDC FA. WARM FRONTOGENESIS
WILL INCREASE ACROSS THE TEXAS PANHANDLE WITH SHOWERS AND
THUNDERSTORMS BLOSSOMING BY EARLY AFTERNOON. THE RAIN AND
THUNDERSTORM ACTIVITY WILL LIFT NORTHEAST DURING THE AFTERNOON HOURS
AND IMPINGE OF THE SOUTHERN/SOUTHEASTER DDC FA BY THE END OF THIS
PERIOD. TEMPERATURES ARE EXPECTED TO WARM INTO THE UPPER 30S TO
LOWER 40S IN THE SOUTHEASTERN PORTION OF THE FORECAST AREA SO AM
EXPECTING PRECIPITATION TYPE TO BE ALL RAIN. POPS WILL BE 30 TO 40
PERCENT IN THE FAR SOUTHEAST DDC FA WITH 20 POPS OVER THE REST OF
THE SOUTHERN THROUGH EAST-CENTRAL ZONES.
MONDAY NIGHT:
TYPICALLY...THE TRACK OF SUCH A FORMIDABLE AND COMPACT STORM SYSTEM
FROM EASTERN NEW MEXICO TO NORTHWEST OKLAHOMA IS FAVORABLE FOR HEAVY
PRECIPITATION ACROSS AT LEAST A PORTION OF THE DDC FORECAST AREA.
THERE WILL BE TWO PROBLEMS THAT WILL MITIGATE HEAVY PRECIPITATION
POTENTIAL FOR A LARGER AREA OF SOUTHWEST KANSAS. 1) 700-500MB MEAN
FLOW FROM ABOUT 230 DEGREES MEANS THAT HEAVY RAIN AND THUNDERSTORM
ACTIVITY THAT FORMS IN THE WARM/MOIST CONVEYOR OVER THE TX PANHANDLE
WILL THEN MOVE INTO FAR NORTHEASTERN TEXAS PANHANDLE/NORTHWEST
OKLAHOMA...THEN INTO SOUTH-CENTRAL KANSAS...CLIPPING THE DDC
FORECAST AREA. 2) LATE DEVELOPMENT OF THE 700MB LOW. MODELS SHOW
THE 700MB LOW DEVELOPING AND MATURING EARLY TUESDAY MORNING OVER
SOUTH CENTRAL KANSAS...SUCH THAT ONCE A "WRAP AROUND" COLD CONVEYOR
CAN DEVELOP AND BECOME ESTABLISHED...IT WILL DO SO JUST EAST OF THE
DDC FA. FOR THESE REASONS...AREAS ALONG AND NORTHWEST OF A LIBERAL
TO DODGE CITY TO LARNED LINE STAND TO SEE A VERY LOW POTENTIAL FOR
BENEFICIAL PRECIPITATION (LESS THAN A TENTH OF AN INCH). FAR
SOUTHEAST DDC FA (I.E. KIOWA IN BARBER COUNTY) COULD SEE OVER
THREE-QUARTERS OF AN INCH BY EARLY TUESDAY MORNING. -UMSCHEID
DAYS 3-7 /TUESDAY THROUGH SATURDAY NIGHT/...
THE PERIOD WILL BEGIN WITH INCREASING UPPER LEVEL RIDGING AND
ISENTROPIC DOWNGLIDE DEVELOPING. NORTHWEST SURFACE WINDS WILL
PROBABLY BE ON THE BREEZY SIDE TUESDAY AS SURFACE PRESSURE INCREASES
ACROSS WESTERN KANSAS AS A LARGE SURFACE ANTICYCLONE SHIFTS EASTWARD
FROM SOUTHEAST KANSAS THROUGH THE MID MISSISSIPPI VALLEY. THESE WINDS
WILL DIMINISH TO LIGHT THROUGH TUESDAY NIGHT AND EARLY WEDNESDAY,
BACKING TO THE SOUTHWEST AGAIN AND BECOMING LIGHT SOUTHWEST THROUGH
THE DAY ON WEDNESDAY. THIS TRANSITION SHOULD SUPPORT WARMING
TEMPERATURES FROM THE 50S ON TUESDAY BACK UP TO AROUND 60 OR MORE ON
WEDNESDAY WITH SOUTHERLY FLOW AND WARM AIR ADVECTION/DOWNSLOPE.
THE UPPER PATTERN WILL REMAIN IN A PROGRESSIVE TROUGH - RIDGE -
TROUGH PATTERN THROUGH THE WEEK. FROM WEDNESDAY NIGHT INTO EARLY
FRIDAY, THE MODELS SWING ANOTHER UPPER JET SEGMENT FROM THE SOUTHERN
ROCKIES INTO THE CENTRAL PLAINS. AS A RESULT, ANOTHER DECENT SURFACE
TROUGH WILL DEVELOP OVER THE CENTRAL HIGH PLAINS ON THURSDAY WHICH
WILL PRODUCE BREEZY TO WINDY SOUTHWEST WINDS AGAIN, BETTER MIXING
AND EVEN WARMER TEMPERATURES INTO THE 60S. AS THE UPPER PATTERN
CONTINUES TO EVOLVE INTO A SHARPER TROUGH OVER THE CENTRAL PLAINS,
ANOTHER STRONG COLD FRONT WILL SWEEP INTO THE HIGH PLAINS FROM
MONTANA AND WYOMING, BRINGING STRONG NORTHWEST WINDS AND COLD
ADVECTION FRIDAY OR FRIDAY NIGHT FOLLOWED BY A COOLING TREND INTO
SUNDAY. -RUSSELL
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 39 23 47 33 / 0 0 20 30
GCK 40 22 47 32 / 0 0 10 20
EHA 46 29 50 35 / 0 0 10 20
LBL 44 26 50 34 / 0 0 10 30
HYS 39 20 47 32 / 0 0 10 20
P28 40 26 48 37 / 10 0 40 80
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN99/99/99
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...
/TODAY THROUGH TUESDAY/
AN AREA OF LOW PRESSURE IS CURRENTLY SKIRTING THE SAINT LAWRENCE
VALLEY...WITH A SURFACE COLD FRONT ALIGNED FROM MICHIGAN DOWN
THROUGH SOUTHERN ILLINOIS AND CENTRAL MISSOURI...WITH UNSEASONABLY
COLD HIGH PRESSURE WORKING INTO THE NORTHERN PLAINS.
MEANWHILE...UNSEASONABLY MILD OVERNIGHT READINGS ARE CURRENTLY BEING
ENJOYED IN EASTERN KENTUCKY...WITH MOST VALUES IN THE 50S AND 60S.
A GOOD LOW LEVEL JET IS IN PLACE ACROSS THE OHIO VALLEY...WITH
ISENTROPIC ASCENT AS WELL AS SOME UPPER LEVEL JET DYNAMICS SETTING
OFF SHOWERS ALONG THE OHIO RIVER.
THE MODELS ARE IN GOOD AGREEMENT WITH DROPPING THIS COLD FRONT
SOUTHEAST TOWARDS THE AREA TODAY. THE BEST FORCING AND MOISTURE
CONVERGENCE LOOKS TO BE NORTH OF THE MOUNTAIN PARKWAY AND NEAR THE
I-64 CORRIDOR...AND WILL CONTINUE TO ADVERTISE THE HIGHEST POPS FOR
THIS AREA. POPS WILL DROP OFF TO THE SOUTHEAST QUICKLY...PARTICULARLY
SOUTH OF THE HAL ROGERS PARKWAY AND HIGHWAY 80. THE BOUNDARY WILL
CONTINUE TO SAG SOUTH ACROSS THE AREA TONIGHT...WITH STEADY SHOWERS
GRADUALLY TAPERING OFF AFTER MIDNIGHT.
THERE WILL BE A LULL IN THE ACTIVITY MONDAY MORNING...BEFORE THE
NEXT WEAK SURFACE WAVE APPROACHES IN THE AFTERNOON FROM THE
SOUTHWEST. EXPECT SCATTERED TO NUMEROUS SHOWERS TO DEVELOP...WITH AN
ISOLATED THUNDERSTORM POSSIBLE. BY MONDAY NIGHT...A MORE STOUT AREA
OF LOW PRESSURE WILL BE RAMPING UP OUT OF THE ARKLATEX REGION AND
MOVE NORTHEAST...DRAGGING THE BOUNDARY BACK NORTH AS A WARM FRONT.
EXPECT ANOTHER ROUND OF HEALTHY SHOWERS WITH SOME EMBEDDED THUNDER
POSSIBLE. THIS WARM FRONT WILL LIFT THROUGH THE AREA TUESDAY
MORNING...WITH ANOTHER GOOD CHANCE OF A LULL IN THE ACTIVITY FOR
TUESDAY AFTERNOON.
AS FAR AS HEAVY RAINFALL GOES...THE MODELS HAVE GENERALLY BEEN
BACKING OFF THE TOTALS ACROSS EASTERN KENTUCKY. STILL...PWATS ARE
HIGH FOR THIS TIME OF YEAR AND THERE ARE SMALL WINDOWS OF INSTABILITY
THAT SUPPORT ISOLATED THUNDER...SO CAN NOT COMPLETELY RULE OUT A FEW
MINOR PROBLEMS OVER TIME...AND WILL CONTINUE TO HIGHLIGHT THIS IN THE
HWO.
FOR TEMPERATURES...GENERALLY USED A BLEND BETWEEN THE GUIDANCE AND THE
INHERITED NUMBERS. UNSEASONABLY MILD READINGS WILL DOMINATE THROUGH
THE SHORT TERM.
.LONG TERM.../TUESDAY NIGHT THROUGH SATURDAY/
MODELS ARE IN SURPRISING GOOD AGREEMENT TO BEGIN THIS FORECAST. LOW
PRESSURE OVER EASTERN INDIANA WITH A WARM FRONT EXTENDING TO ERN PA
AND A COLD FRONT SOUTH BETWEEN EVV AND SDF. THE GFS IS ABOUT 50
MILES MORE ADVANCED WITH THE COLD FRONT THAN THE ECMWF SO HAVE USED
A COMPROMISE. BY SUNRISE ON WED THE CLD FRONT HAS MADE THE LEAP TO
THE ERN SLOPES OF THE APPALACHIANS AND PCP IS MOVING OUT OF KY. THE
ECMWF IS ABOUT 6 HRS SLOWER WITH THE DEPARTING SYSTEM AND DOES NOT
BRING IN THE COOLER AIR ON THE NORTHERLY WIND UNTIL NEARLY 00Z ON
THU. BY 12Z BOTH MODELS HAVE THE HIGH PRESSURE CENTERED NEARLY
OVERHEAD OF ERN KY. THE GFS DOES BEGIN BRINGING MOISTURE NORTH
AROUND THE BACK SIDE OF THE HIGH PRESSURE BY FRI MORNING AND PLACES
PCPN ALONG THE MISS RIVER BY FRI AFTERNOON. WHERE AS THE ECMWF DOES
NOT BRING RETURN MOISTURE UNTIL LATE FRIDAY AND ANY PCPN FRI
AFTERNOON IS STILL CONFINED TO THE PLAINS. THE NEXT COLD FRONT WILL
PUSH INTO AND THROUGH ERN KY ON SUNDAY. AGAIN THE GFS IS FASTER BY
ALMOST 12 HRS THIS TIME AND THE MODEL CONSENSUS HAS MADE FOR A DECENT
COMPROMISE WITH THE FIRST PCPN LEADING THE FRONT ON SAT AFTERNOON.
EXPECT TEMPERATURES TO TAKE AN INITIAL TUMBLE WITH WED HIGHS ONLY IN
THE LOWER 50S BUT WARMING TO THE MID 50S BY THANKSGIVING AND THEN
INTO THE 60S FOR FRI AND INTO SAT. BY SUN THE NEXT COLD FRONT WILL
ONCE AGAIN DROP HIGH TEMPS TO THE 50S.
&&
.AVIATION.../12Z TO 12Z/
LOW LEVEL WIND SHEAR WILL HANG ON A COUPLE OF MORE HOURS...BEFORE
SUBSIDING. SHOWERS AND LOWERING CEILINGS WILL GRADUALLY MOVE IN FROM
THE WEST THIS MORNING AND ESPECIALLY THIS AFTERNOON. MVFR CEILINGS
WILL THEN DROP TO AT LEAST IFR OVERNIGHT TONIGHT AS STEADIER SHOWERS
WIND DOWN ACROSS THE AREA.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...GEOGERIAN/KAS
LONG TERM....DUSTY
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
528 AM CST SUN NOV 20 2011
.AVIATION...
LOW CLOUDS WILL BE PRESENT THROUGH MOST OF THIS FORECAST CYCLE AS A
COLD FRONT ENCROACHES AND THEN STALLS NEAR THE METROPLEX TODAY.
ONE OF THE MANY CHALLENGES TO THIS FORECAST IS HOW FAR SOUTHEAST
THE FRONT WILL MAKE IT BEFORE COMING TO REST...THEN WHEN IT WILL
LIFT NORTH AS THE WEST COAST UPPER LOW DEEPENS AND APPROACHES THE
REGION. A MODEL BLEND SEEMS MOST LOGICAL AT THIS TIME FOR FRONTAL
POSITION AND RESPECTIVE WIND FORECAST AT THE AREA TERMINALS. NAM
AND RUC ARE WELL AHEAD OF THE GFS ON SOUTHEASTWARD MOVEMENT OF THE
BOUNDARY...BUT APPEAR TO HAVE INITIALIZED ITS POSITION TOO FAR
SOUTHEAST. GFS JUST SEEMS TOO SLOW ON THE FORWARD PROGRESS. FOR
THIS FORECAST SET...WILL CONTINUE WITH THE IFR CIGS UNTIL MID-LATE
MORNING WITH VEERING WINDS AHEAD OF THE FRONT. MVFR CONDITIONS
THEN EXPECTED THE REST OF THE DAY AND WILL ADVERTISE FROPA AT OR
JUST BEFORE NOON LOCAL FOR THE METRO AREA TAF SITES. WILL INDICATE
VEERING WINDS AT ACT BUT THINK THE BOUNDARY MAY BECOME STATIONARY
BEFORE REACHING THE ACT TERMINAL. FRONT WILL THEN LIFT NORTH
TOMORROW MORNING BRINGING SE WINDS AREA-WIDE.
WILL INCLUDE VCSH BEGINNING MIDDAY TODAY. FEEL THE BEST CHANCES
FOR THUNDERSTORMS WILL BE TONIGHT AS OVERALL ASCENT INCREASES AND
THE FRONT PROVIDES FOCUS FOR DEVELOPMENT. CB IS POSSIBLE LATE THIS
AFTERNOON...BUT WITH THE PRESENCE OF A CAP THROUGH MOST OF THE DAY
WILL HOLD OFF MENTION OF CB UNTIL 21/02Z WHEN LOW LEVEL JET BEGINS
TO MATERIALIZE AND ELEVATED TS BECOME MORE LIKELY.
30
&&
.PREV DISCUSSION... /ISSUED 508 AM CST SUN NOV 20 2011/
EARLY MORNING WATER VAPOR IMAGERY DEPICTED SHORTWAVE TROUGHS OVER
THE NORTHERN CONUS ROCKIES...OVER THE BAJA PENINSULA AND JUST OFF
THE NORTHERN CA COAST. A PLUME OF TROPICAL PACIFIC MOISTURE WAS
STREAMING OVER THE SOUTHERN ROCKIES AND OVER THE SOUTHERN PLAINS.
A COLD FRONT CHARACTERIZED BY A STRONG LOW LEVEL BAROCLINIC ZONE
REMAINED JUST TO THE NORTHWEST OF THE CWA AS OF 09Z...AND WAS
LOCATED APPROXIMATELY ALONG AN ARDMORE TO THROCKMORTON LINE.
ALTHOUGH THE FRONT HAS SLOWED DOWN SIGNIFICANTLY OVERNIGHT...IT
CONTINUES TO PUSH SOUTHEAST EARLY THIS MORNING AND WILL LIKELY
ENTER THE FAR NORTHWESTERN COUNTIES OF OUR FORECAST AREA BY 12Z.
TEMPERATURES FALL RAPIDLY BEHIND/NORTH OF THE FRONT WITH A 09Z
TEMPERATURE OF 61 AT BOWIE AND ONLY 46 AT WICHITA FALLS.
TODAY AND TONIGHT...THE BAJA SHORTWAVE TROUGH IS EXPECTED TO MOVE
QUICKLY NORTHEAST DURING THE DAY TODAY AND IS EXPECTED TO BE
LOCATED OVER THE CENTRAL PLAINS BY EARLY THIS EVENING. THIS FAST
MOVING BUT SOMEWHAT WEAK TROUGH WILL SPREAD SOME LARGE SCALE
FORCING FOR ASCENT OVER THE SOUTHERN PLAINS TODAY AHEAD OF THE
COLD FRONT. THE TROUGH ITSELF IS EXPECTED TO REMAIN WELL TO THE
NORTH OF THE CWA...SO IT WILL LIKELY NOT PLAY A SIGNIFICANT ROLE IN
PRECIPITATION CHANCES DURING THE PERIOD. TODAYS PRIMARY FORECAST
CHALLENGE IS WITH REGARDS TO CONVECTIVE INITIATION ALONG THE COLD
FRONT...WHICH IS EXPECTED TO STALL OUT SOMEWHERE OVER NORTH TX BY
EARLY THIS AFTERNOON.
ONE CHALLENGE REGARDING CONVECTIVE INITIATION THIS AFTERNOON IS
FORECASTING WHERE THE FRONT WILL STALL OUT. 00 AND 06Z GUIDANCE
HAS FAILED TO COME UP WITH A CONSENSUS POSITION OF THE STALLED OUT
FRONT. THE COARSER RESOLUTION GUIDANCE INDICATES THAT THE FRONT
WILL STALL OUT NEAR THE DFW METROPLEX WHILE THE HIGHER RESOLUTION
GUIDANCE INDICATES THAT THE FRONT WILL MAKE IT AS FAR SOUTHEAST AS
A SULPHUR SPRINGS TO HILLSBORO TO GOLDTHWAITE LINE. NEITHER
SOLUTION INITIALIZED THE CURRENT POSITION OF THE FRONT
PERFECTLY...SO OPTED TO GO WITH A BLEND AND JUST PUSHED THE FRONT
FURTHER SOUTHEAST THAN PREVIOUS FORECAST HAD INDICATED FOR THIS
AFTERNOON. THINK THAT BEST PRECIPITATION CHANCES WILL REMAIN ALONG
THE FRONTAL BOUNDARY FOR THIS AFTERNOON...SO ADJUSTED POPS
ACCORDINGLY TAKING THE HIGHER AXIS OF 40/50 POPS A BIT FURTHER
SOUTHEAST FOR THIS AFTERNOON AND THIS EVENING.
THE OTHER CHALLENGE REGARDING CONVECTIVE INITIATION TODAY IS
IDENTIFYING A STRONG FORCING MECHANISM. THE STALLED OUT COLD FRONT
IS THE OBVIOUS FEATURE IN PLAY BUT THE LIMITING FACTOR REGARDING
FORCING ALONG THE FRONT IS THE FACT THAT IT IS EXPECTED TO BE
STATIONARY BY THIS AFTERNOON. WITHOUT MOVEMENT THERE WILL NO
FORCED CONVECTION OUT AHEAD OF THE FRONT ASSOCIATED WITH DYNAMIC
PRESSURE PERTURBATIONS. THE PRIMARY FORCING MECHANISM ASSOCIATED
WITH THE FRONT THEN APPEARS TO BE FRONTOGENESIS WHICH IS TYPICALLY
MAXIMIZED BEHIND THE LEADING EDGE OF THE SURFACE FRONT. MOST SREF
ENSEMBLE MEMBERS DEPICT A LOW LEVEL CAPPING INVERSION IN PLACE
OVER NORTH TX THIS AFTERNOON. WHILE WE WILL HAVE SOME MODEST LOW
LEVEL WARM AIR ADVECTION SOUTH OF THE FRONTAL BOUNDARY TODAY THE
PRESENCE OF THIS CAP /ASSUMING IT EXISTS/ SHOULD LIMIT THE
INITIATION OF TSTM ACTIVITY TO THE IMMEDIATE VICINITY OF THE FRONT.
WITH THIS IN MIND NARROWED THE BAND 30 TO 50 POPS TODAY TO THOSE
LOCATIONS WHERE THE FRONT MAY REASONABLY STALL OUT. DID NOT GO ANY
HIGHER THAN 50 POPS IN THE CWA THRU 00Z AS ALL CONVECTION ALLOWING
GUIDANCE KEEPS TSTM ACTIVITY OUT OF NORTH TX THIS AFTERNOON WHILE
ALL OTHER GUIDANCE INDICATES DEVELOPING CONVECTION ALONG THE FRONT
BETWEEN 21 TO 00Z. THE LACK OF LARGE SCALE FORCING FOR ASCENT
TENDS TO FAVOR A SLOW LIFTING OR STRONGER CAP SO WILL REMAIN
CAUTIOUS WITH REGARDS TO POPS UNTIL 12Z UPPER AIR DATA COMES IN AS
WELL AS AIRCRAFT DATA SOUNDING DATA LATER THIS MORNING.
IF TSTMS ARE ABLE TO INITIATE ALONG THE FRONT THIS
AFTERNOON...THERE IS A CHANCE THAT THEY WILL BECOME SEVERE. SREF
MEAN SURFACE BASED CAPE VALUES ARE AROUND 1000 J/KG SOUTH OF THE
FRONT TODAY AND ALL OPERATIONAL GUIDANCE ADVERTISES AT LEAST THIS
MUCH POTENTIAL INSTABILITY. DEEP LAYER SHEAR IS EXPECTED TO BE
AROUND 40 TO 50 KTS THIS AFTERNOON WHICH WOULD SUPPORT AN
ORGANIZED CONVECTIVE MODE. DEW POINT VALUES THIS MORNING ARE
EXCEPTIONALLY HIGH FOR NOVEMBER...WITH DEW POINTS IN THE LOWER 70S
OBSERVED FROM HEARNE SOUTHEAST TO THE GULF COAST. WE WOULD NEED
JUST A FEW BREAKS IN THE LOW CLOUD COVER THIS AFTERNOON TO SEE
CAPE VALUES JUMP UP ABOVE 1000 J/KG. BECAUSE CLOUDS ARE EXPECTED
TO HOLD IN FOR MUCH OF THE DAY...OVERALL TORNADO POTENTIAL IS LOW
DUE TO POOR LOW LEVEL LAPSE RATES LIMITING VORTEX STRETCHING
POTENTIAL. LARGE HAIL LOOKS TO BE THE PRIMARY THREAT IN THIS
ENVIRONMENT WITH THE DAMAGING WIND AND TORNADO POTENTIAL PERKING
UP IN ANY AREAS THAT SEE A FEW HOURS OF SUNSHINE TODAY. WOULD
EXPECT A LARGELY LINEAR/QLCS STORM MODE AS DEEP LAYER SHEAR
VECTORS ARE EXPECTED TO BE NEARLY PARALLEL TO THE STATIONARY
FRONT.
TSTM ACTIVITY IS EXPECTED TO INCREASE IN COVERAGE TONIGHT AS THE
SHALLOW COLD FRONT INTERACTS WITH THE DEVELOPING LOW LEVEL JET.
THE LOW LEVEL JET IS EXPECTED TO RAMP UP IN ADVANCE OF THE NEXT
APPROACHING SHORTWAVE TROUGH WHICH IS MUCH STRONGER THAN THE BAJA
TROUGH. THE COLD FRONT WILL EFFECTIVELY STEEPEN LOW LEVEL
ISENTROPIC SURFACES ALLOWING FOR SIGNIFICANT ISENTROPIC LIFT
AFTER MIDNIGHT AS THE LLJ RIDES OVER THIS BOUNDARY. THIS FORCING
IS MUCH MORE BROAD THAN THE NARROW FRONTOGENETIC FORCING ALONG THE
FRONT...SO WENT AHEAD AND SPREAD POPS OUT OVER MUCH OF NORTH TX
LATE OVERNIGHT AND THRU MONDAY MORNING AS THE FRONT GRADUALLY
LIFTS BACK NORTH MONDAY MORNING. STORMS SUNDAY NIGHT WILL LIKELY
BE ELEVATED IN NATURE AND SHOULD ONLY POSE A LOWER END SEVERE HAIL
THREAT.
MONDAY AFTERNOON THRU TUESDAY...THE TROUGH THAT CURRENTLY RESIDES
OFF THE NORTHERN CA COAST WILL MOVE THRU THE SOUTHERN PLAINS LATE
MONDAY AFTERNOON THRU THE EVENING HRS. THIS SHOULD RESULT IN
WIDESPREAD TSTM ACTIVITY THRU MUCH OF THE REGION DURING THIS
PERIOD. WITH STRONG FORCING FOR ASCENT ASSOCIATED WITH THE
POWERFUL UPPER TROUGH WENT AHEAD WITH SREF SUGGESTED POPS DUE TO
THE STRONG SYNOPTIC SIGNALS IN PLACE.
FOR OUR CWA...MOST CONFIDENT IN TSTM ACTIVITY NEAR ANY FRONTAL
BOUNDARY DURING THE PERIOD SO HAVE PLACED 80 POPS OR HIGHER NEAR
THE EXPECTED POSITION OF SYNOPTIC FRONTS. ANY STORMS THAT DEVELOP
MONDAY AFTERNOON OR EVENING WILL HAVE THE POTENTIAL TO BECOME
SEVERE WITH DEEP MOISTURE AND EVEN STRONGER SHEAR IN PLACE THAN
WHAT IS EXPECTED FOR SUNDAY AFTERNOON. PRIMARY SEVERE
THUNDERSTORM HAZARDS WILL BE DEPENDENT UPON WHERE FRONTAL
BOUNDARIES LIE AND WHERE STORMS DEVELOP. WHILE THE CONFIDENCE OF
TSTMS OCCURRING IS HIGH...THE CONFIDENCE REGARDING THESE DETAILS
IS FAIRLY LOW AT THIS TIME.
STORMS THAT DEVELOP ALONG THE RETREATING FRONTAL BOUNDARY/WARM
FRONT MONDAY AFTERNOON WILL TEND TO BE MORE QUASI-LINEAR IN
NATURE AS DEEP LAYER SHEAR REMAINS NEARLY PARALLEL TO THIS
BOUNDARY WITH LITTLE IN THE WAY OF A CAP IN PLACE. HEAVY RAINFALL
POTENTIAL IS CERTAINLY THERE DUE TO THE POTENTIAL FOR STORMS TO
TRAIN OVER ONE ANOTHERS TRACK NEAR THE WARM FRONT. A MORE DISCRETE
MODE MAY BE EXPECTED ALONG THE DRYLINE MONDAY AFTERNOON...HOWEVER
THIS BOUNDARY IS EXPECTED TO BE PLACED WELL WEST OF THE CWA. IT
IS POSSIBLE FOR DISCRETE STORMS/SUPERCELLS TO DEVELOP OUT WEST AND
THEN MOVE EAST INTO THE CWA LATE MONDAY AFTERNOON. STORMS WILL
INCREASE IN COVERAGE MONDAY EVENING AS THE ENTIRE STORM SYSTEM
BEGINS TO MOVE NORTHEAST AND A COLD FRONT MOVES THRU THE AREA ONCE
AGAIN. UNLIKE TODAY...THIS FRONT IS EXPECTED TO MOVE ALL THE WAY
THRU NORTH TX BY TUESDAY MORNING. FORCING ALONG THE MOVING COLD
FRONT WILL ONCE AGAIN PROMOTE QLCS/MULTICELL ACTIVITY DEPENDING ON
POTENTIAL INSTABILITY AFTER SUNSET.
FOR MONDAY AFTERNOON...STORMS NEAR THE WARM FRONT WILL CONTINUE TO
HAVE A PRIMARILY LARGE HAIL SEVERE TSTM THREAT WITH ENHANCED
DAMAGING WIND AND TORNADO POTENTIAL FOR ANY AREAS THAT RECEIVE A
FEW HRS OF SUNSHINE. IF DISCRETE SUPERCELLS ARE ABLE TO ORGANIZE
TO OUR WEST...THESE WOULD HAVE A MORE PROMINENT TORNADO AND
DAMAGING WIND THREAT AS WELL AS AN ATTENDANT LARGE HAIL. UNLESS
THIS ACTIVITY IS ABLE TO MOVE INTO THE CWA OR DEVELOP IN THE WAA
REGIME AWAY FROM FRONTAL BOUNDARIES BEFORE SUNSET...THE OVERALL
TORNADO POTENTIAL MAY BE LOW MONDAY AFTERNOON AND EVENING. THESE
DETAILS WILL BE DIFFICULT TO RESOLVE UNTIL TOMORROW WHEN
CONFIDENCE IS HIGHER ON THE PLACEMENT OF SYNOPTIC FEATURES.
EXTENDED...DID NOT MAKE SIGNIFICANT CHANGES TO THE EXTENDED.
BEHIND THE COLD FRONT WE SHOULD SEE A FEW DAYS OF DRY WEATHER
AHEAD OF THE NEXT POWERFUL SHORTWAVE TROUGH. THIS TROUGH IS
EXPECTED TO MOVE INTO THE SOUTHERN PLAINS FRIDAY AFTERNOON OR
FRIDAY NIGHT. 00Z GUIDANCE WAS IN FAIRLY GOOD AGREEMENT ON THE
TIMING OF THIS FEATURE...AND POPS WILL NEED TO BE INCREASED IF
THIS CONSENSUS REMAINS IN TACT MOVING FORWARD. FOR NOW HAVE BROAD
BRUSHED 20 AND 30 POPS FOR FRIDAY AND FRIDAY NIGHT.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 76 62 75 61 70 / 30 50 80 90 50
WACO, TX 82 69 80 64 76 / 30 30 50 70 60
PARIS, TX 76 63 74 62 69 / 50 60 80 90 70
DENTON, TX 72 55 71 56 67 / 30 50 80 90 40
MCKINNEY, TX 74 60 74 60 69 / 30 50 80 90 50
DALLAS, TX 78 64 77 63 70 / 30 50 80 90 50
TERRELL, TX 79 67 79 65 72 / 40 50 60 90 70
CORSICANA, TX 82 68 81 68 75 / 40 50 40 80 80
TEMPLE, TX 84 70 82 66 78 / 20 30 30 70 70
MINERAL WELLS, TX 71 55 72 53 69 / 30 40 80 90 30
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
30/69
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
412 PM EST SUN NOV 20 2011
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE WILL CAUSE A FEW SHOWERS THIS
AFTERNOON INTO THE EVENING HOURS. OTHERWISE...HIGH PRESSURE
COVERING THE AREA WILL MOVE EAST TONIGHT AND MONDAY. A COLD FRONT
WILL APPROACH FROM THE WEST MONDAY AND TUESDAY INCREASING THE
CHANCES FOR SHOWERS BY TUESDAY. A FEW THUNDERSTORMS ARE ALSO
POSSIBLE TUESDAY AFTERNOON AND TUESDAY EVENING. THE COLD FRONT
WILL MOVE THROUGH WEDNESDAY WITH A GOOD CHANCE OF SHOWERS...
MAINLY IN THE MORNING. THANKSGIVING DAY WILL BE MOSTLY SUNNY
WITH DRY WEATHER EXPECTED.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
UPDATE...DUE TO CURRENT RAINFALL MOVING ACROSS THE MIDLANDS...HAVE
UPPED POPS ACROSS THE CENTRAL AND EASTERN COUNTIES TO CATEGORICAL
FOR THE NEXT FEW HOURS. TEMPS AND CLOUDS HAVE ALSO BEEN ADJUSTED
ACCORDINGLY.
PREVIOUS DISCUSSION...BOTH THE RUC AND NAM MODELS SHOW A WEAK
SHORT WAVE MOVING ACROSS THE REGION THIS AFTERNOON INTO THE
EVENING HOURS. LIKE THE 12 KM NAM 3 HOURLY POPS SHOWING A 20-30
PERCENT CHANCE OF SHOWERS THIS AFTERNOON AND A 20 PERCENT CHANCE
MAINLY IN NORTHERN AND WESTERN LOCATIONS THIS EVENING. THEN
AREAS OF FOG ARE EXPECTED TO DEVELOP AFTER MIDNIGHT WITH THE HIGH
MOISTURE CONTENT OF THE ATMOSPHERE. LOWS SHOULD BE IN THE MIDDLE
50S TONIGHT.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
HIGH PRESSURE WILL CONTINUE TO MOVE TO THE EAST AS A SHORT WAVE
AND AN ASSOCIATED COLD FRONT APPROACH FROM THE WEST MONDAY NIGHT
AND TUESDAY. A HIGH AMOUNT OF CLOUD COVER SHOULD KEEP AFTERNOON
HIGHS FROM REACHING THE 80 DEGREE MARK BUT NOT BY MUCH. WILL GO
MIDDLE TO UPPER 70S MONDAY AND TUESDAY. WILL INTRODUCE A SLIGHT
CHANCE OF SHOWERS TUESDAY AFTERNOON WITH THUNDERSTORMS POSSIBLE
TUESDAY AFTERNOON AND TUESDAY EVENING WITH THE MOST UNSTABLE
CONDITIONS DURING THIS PERIOD. LATER TUESDAY NIGHT...WILL JUST
MENTION SHOWERS. CHANCES INCREASE FROM 30 PERCENT TO 50 PERCENT
TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
MEDIUM RANGE MODELS IN GOOD AGREEMENT MOVING SHORT WAVE AND
ASSOCIATED COLD FRONT THROUGH AREA WEDNESDAY. A GOOD CHANCE OF
SHOWERS EARLY WEDNESDAY...THEN CHANCES DECREASE DURING THE DAY
AS A COLD FRONT MOVES EAST. DECIDED TO NOT MENTION THUNDER
WEDNESDAY AS FRONT MOVES THROUGH EARLY. HIGH PRESSURE BUILDS OVER
THE REGION THANKSGIVING DAY THROUGH SATURDAY AS NEXT SYSTEM
APPEARS TO BE LATER THAN SATURDAY. HIGHS WEDNESDAY IN THE LOWER
70S COOL TO THE LOWER TO MIDDLE 60S THURSDAY THROUGH SATURDAY.
OVERNIGHT LOWS IN THE 40S WEDNESDAY NIGHT DROP TO THE 30S THURSDAY
NIGHT BUT ARE BACK UP AROUND 40 FOR FRIDAY NIGHT.
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
UPDATE...BATCH OF RAIN HAS SHIFTED EAST OF THE TERMINALS AND IS
SHOWING A TREND TOWARDS DECREASING IN INTENSITY AND COVERAGE.
LOWER VSBYS/CIGS AT DNL/AGS REMAIN...THOUGH VSBYS/CIGS AT CAE/CUB
HAVE IMPROVED. WILL MAINTAIN PERSISTENCE IN THE SHORT TERM AND
EXPECT SOME IMPROVEMENT EARLY THIS EVENING. DETERIORATING
CONDITIONS POSSIBLE AGAIN LATE TONIGHT. MODELS ARE SUGGESTING IFR
VSBYS/CIGS AFTER 08Z. VFR CONDITIONS RETURN BY 14Z MONDAY.
EXTENDED AVIATION OUTLOOK...PERIODS OF MVFR OR IFR CEILING MAY OCCUR
TUESDAY NIGHT INTO WEDNESDAY ASSOCIATED WITH THE APPROACH OF A
FRONTAL SYSTEM FROM THE NORTHWEST.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AVIATION...DCM
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
319 PM EST SUN NOV 20 2011
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE WILL CAUSE A FEW SHOWERS THIS
AFTERNOON INTO THE EVENING HOURS. OTHERWISE...HIGH PRESSURE
COVERING THE AREA WILL MOVE EAST TONIGHT AND MONDAY. A COLD FRONT
WILL APPROACH FROM THE WEST MONDAY AND TUESDAY INCREASING THE
CHANCES FOR SHOWERS BY TUESDAY. A FEW THUNDERSTORMS ARE ALSO
POSSIBLE TUESDAY AFTERNOON AND TUESDAY EVENING. THE COLD FRONT
WILL MOVE THROUGH WEDNESDAY WITH A GOOD CHANCE OF SHOWERS...
MAINLY IN THE MORNING. THANKSGIVING DAY WILL BE MOSTLY SUNNY
WITH DRY WEATHER EXPECTED.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
UPDATE...DUE TO CURRENT RAINFALL MOVING ACROSS THE MIDLANDS...HAVE
UPPED POPS ACROSS THE CENTRAL AND EASTERN COUNTIES TO CATEGORICAL
FOR THE NEXT FEW HOURS. TEMPS AND CLOUDS HAVE ALSO BEEN ADJUSTED
ACCORDINGLY.
PREVIOUS DISCUSSION...BOTH THE RUC AND NAM MODELS SHOW A WEAK
SHORT WAVE MOVING ACROSS THE REGION THIS AFTERNOON INTO THE
EVENING HOURS. LIKE THE 12 KM NAM 3 HOURLY POPS SHOWING A 20-30
PERCENT CHANCE OF SHOWERS THIS AFTERNOON AND A 20 PERCENT CHANCE
MAINLY IN NORTHERN AND WESTERN LOCATIONS THIS EVENING. THEN
AREAS OF FOG ARE EXPECTED TO DEVELOP AFTER MIDNIGHT WITH THE HIGH
MOISTURE CONTENT OF THE ATMOSPHERE. LOWS SHOULD BE IN THE MIDDLE
50S TONIGHT.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
HIGH PRESSURE WILL CONTINUE TO MOVE TO THE EAST AS A SHORT WAVE
AND AN ASSOCIATED COLD FRONT APPROACH FROM THE WEST MONDAY NIGHT
AND TUESDAY. A HIGH AMOUNT OF CLOUD COVER SHOULD KEEP AFTERNOON
HIGHS FROM REACHING THE 80 DEGREE MARK BUT NOT BY MUCH. WILL GO
MIDDLE TO UPPER 70S MONDAY AND TUESDAY. WILL INTRODUCE A SLIGHT
CHANCE OF SHOWERS TUESDAY AFTERNOON WITH THUNDERSTORMS POSSIBLE
TUESDAY AFTERNOON AND TUESDAY EVENING WITH THE MOST UNSTABLE
CONDITIONS DURING THIS PERIOD. LATER TUESDAY NIGHT...WILL JUST
MENTION SHOWERS. CHANCES INCREASE FROM 30 PERCENT TO 50 PERCENT
TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
MEDIUM RANGE MODELS IN GOOD AGREEMENT MOVING SHORT WAVE AND
ASSOCIATED COLD FRONT THROUGH AREA WEDNESDAY. A GOOD CHANCE OF
SHOWERS EARLY WEDNESDAY...THEN CHANCES DECREASE DURING THE DAY
AS A COLD FRONT MOVES EAST. DECIDED TO NOT MENTION THUNDER
WEDNESDAY AS FRONT MOVES THROUGH EARLY. HIGH PRESSURE BUILDS OVER
THE REGION THANKSGIVING DAY THROUGH SATURDAY AS NEXT SYSTEM
APPEARS TO BE LATER THAN SATURDAY. HIGHS WEDNESDAY IN THE LOWER
70S COOL TO THE LOWER TO MIDDLE 60S THURSDAY THROUGH SATURDAY.
OVERNIGHT LOWS IN THE 40S WEDNESDAY NIGHT DROP TO THE 30S THURSDAY
NIGHT BUT ARE BACK UP AROUND 40 FOR FRIDAY NIGHT.
&&
.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
HIGH PRESSURE NOW WELL OFF THE ATLANTIC COAST WITH A FRONTAL SYSTEM
IN THE OHIO VALLEY. PATCHY LIGHT SHOWERS ACROSS THE CSRA AND
PORTIONS OF THE CENTRAL MIDLANDS WILL PERSIST FOR THE NEXT COUPLE OF
HOURS DUE TO A WEAK UPPER-LEVEL DISTURBANCE. OTHERWISE VFR THROUGH
THE DAY WITH LIGHT S-SW WINDS AND CONTINUED MID LEVEL CLOUDS.
MODELS ARE STRONGLY SUGGESTING POSSIBLE IFR VSBYS/CIGS AFTER
08Z...ESPECIALLY AGS/DNL/OGB...ESPECIALLY IF LOW-LEVEL NOCTURNAL JET
DOES NOT DEVELOP. VFR CONDITIONS RETURN BY 14Z MONDAY WITH BKN CIGS
AROUND 4000 FT.
EXTENDED AVIATION OUTLOOK...PERIODS OF MVFR OR IFR CEILING MAY OCCUR
TUESDAY NIGHT INTO WEDNESDAY ASSOCIATED WITH THE APPROACH OF A
FRONTAL SYSTEM FROM THE NORTHWEST.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
149 PM EST SUN NOV 20 2011
.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE WILL CAUSE A FEW SHOWERS THIS
AFTERNOON INTO THE EVENING HOURS. OTHERWISE...HIGH PRESSURE
COVERING THE AREA WILL MOVE EAST TONIGHT AND MONDAY. A COLD FRONT
WILL APPROACH FROM THE WEST MONDAY AND TUESDAY INCREASING THE
CHANCES FOR SHOWERS BY TUESDAY. A FEW THUNDERSTORMS ARE ALSO
POSSIBLE TUESDAY AFTERNOON AND TUESDAY EVENING. THE COLD FRONT
WILL MOVE THROUGH WEDNESDAY WITH A GOOD CHANCE OF SHOWERS...
MAINLY IN THE MORNING. THANKSGIVING DAY WILL BE MOSTLY SUNNY
WITH DRY WEATHER EXPECTED.
&&
.NEAR TERM /THROUGH TONIGHT/...
BOTH THE RUC AND NAM MODELS SHOW A WEAK SHORT WAVE MOVING ACROSS
THE REGION THIS AFTERNOON INTO THE EVENING HOURS. LIKE THE 12 KM
NAM 3 HOURLY POPS SHOWING A 20-30 PERCENT CHANCE OF SHOWERS THIS
AFTERNOON AND A 20 PERCENT CHANCE MAINLY IN NORTHERN AND WESTERN
LOCATIONS THIS EVENING. THE NAM ALSO HAD A 40 PERCENT POP THIS
AFTERNOON NEAR AGS BUT JUST BRIEFLY. THEN AREAS OF FOG ARE
EXPECTED TO DEVELOP AFTER MIDNIGHT WITH THE HIGH MOISTURE CONTENT
OF THE ATMOSPHERE. LOWS SHOULD BE IN THE MIDDLE 50S TONIGHT.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
HIGH PRESSURE WILL CONTINUE TO MOVE TO THE EAST AS A SHORT WAVE
AND AN ASSOCIATED COLD FRONT APPROACH FROM THE WEST MONDAY NIGHT
AND TUESDAY. A HIGH AMOUNT OF CLOUD COVER SHOULD KEEP AFTERNOON
HIGHS FROM REACHING THE 80 DEGREE MARK BUT NOT BY MUCH. WILL GO
MIDDLE TO UPPER 70S MONDAY AND TUESDAY. WILL INTRODUCE A SLIGHT
CHANCE OF SHOWERS TUESDAY AFTERNOON WITH THUNDERSTORMS POSSIBLE
TUESDAY AFTERNOON AND TUESDAY EVENING WITH THE MOST UNSTABLE
CONDITIONS DURING THIS PERIOD. LATER TUESDAY NIGHT...WILL JUST
MENTION SHOWERS. CHANCES INCREASE FROM 30 PERCENT TO 50 PERCENT
TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
MEDIUM RANGE MODELS IN GOOD AGREEMENT MOVING SHORT WAVE AND
ASSOCIATED COLD FRONT THROUGH AREA WEDNESDAY. A GOOD CHANCE OF
SHOWERS EARLY WEDNESDAY...THEN CHANCES DECREASE DURING THE DAY
AS A COLD FRONT MOVES EAST. DECIDED TO NOT MENTION THUNDER
WEDNESDAY AS FRONT MOVES THROUGH EARLY. HIGH PRESSURE BUILDS OVER
THE REGION THANKSGIVING DAY THROUGH SATURDAY AS NEXT SYSTEM
APPEARS TO BE LATER THAN SATURDAY. HIGHS WEDNESDAY IN THE LOWER
70S COOL TO THE LOWER TO MIDDLE 60S THURSDAY THROUGH SATURDAY.
OVERNIGHT LOWS IN THE 40S WEDNESDAY NIGHT DROP TO THE 30S THURSDAY
NIGHT BUT ARE BACK UP AROUND 40 FOR FRIDAY NIGHT.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
HIGH PRESSURE NOW WELL OFF THE ATLANTIC COAST WITH A FRONTAL SYSTEM
IN THE OHIO VALLEY. PATCHY LIGHT SHOWERS ACROSS THE CSRA AND
PORTIONS OF THE CENTRAL MIDLANDS WILL PERSIST FOR THE NEXT COUPLE OF
HOURS DUE TO A WEAK UPPER-LEVEL DISTURBANCE. OTHERWISE VFR THROUGH
THE DAY WITH LIGHT S-SW WINDS AND CONTINUED MID LEVEL CLOUDS.
MODELS ARE STRONGLY SUGGESTING POSSIBLE IFR VSBYS/CIGS AFTER
08Z...ESPECIALLY AGS/DNL/OGB...ESPECIALLY IF LOW-LEVEL NOCTURNAL JET
DOES NOT DEVELOP. VFR CONDITIONS RETURN BY 14Z MONDAY WITH BKN CIGS
AROUND 4000 FT.
EXTENDED AVIATION OUTLOOK...PERIODS OF MVFR OR IFR CEILING MAY OCCUR
TUESDAY NIGHT INTO WEDNESDAY ASSOCIATED WITH THE APPROACH OF A
FRONTAL SYSTEM FROM THE NORTHWEST.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...07
NEAR TERM...07
SHORT TERM...07
LONG TERM...07
AVIATION...22
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
333 PM EST SUN NOV 20 2011
.UPDATE...
THE SYNOPSIS...NEAR TERM...SHORT TERM AND LONG TERM SECTIONS HAVE
BEEN UPDATED BELOW.
&&
.SYNOPSIS...
A FRONTAL BOUNDARY WILL REMAIN NEARLY STATIONARY ACROSS THE LOWER
OHIO VALLEY THROUGH MONDAY EVENING...KEEPING SKIES CLOUDY ALONG WITH
PERIODIC CHANCES FOR RAIN. A STRONG WAVE OF LOW PRESSURE WILL TRACK
ALONG THE FRONT AND INTO THE REGION ON TUESDAY...WITH WIDESPREAD
RAIN AND A FEW THUNDERSTORMS ANTICIPATED. RAIN WILL END TUESDAY
NIGHT AS THE FRONT PULLS AWAY TO THE EAST. LARGE HIGH PRESSURE WILL
BUILD IN FOR THE SECOND HALF OF THE WEEK WITH DRY AND MILD WEATHER
FOR CENTRAL INDIANA. THE CHANCE FOR RAIN WILL RETURN NEXT WEEKEND AS
A FRONTAL BOUNDARY APPROACHES FROM THE WEST.
&&
.NEAR TERM /TONIGHT/...
COLD FRONT HAS MOVED SOUTH OF THE FORECAST AREA AS OF MID
AFTERNOON...RUNNING ALONG THE OHIO RIVER. AREA OF STEADIER RAINFALL
PROGRESSING EASTWARD ACROSS MUCH OF THE SOUTHERN HALF OF THE
FORECAST AREA THIS AFTERNOON ASSOCIATED WITH A WAVE OF LOW PRESSURE
TRAVERSING THE BOUNDARY. TEMPS WERE GENERALLY IN THE UPPER 40S AND
LOWER 50S AS OF 19Z.
FOCUS TONIGHT IS ON PRECIP CHANCES AS FRONT BECOMES NEARLY
STATIONARY JUST SOUTH OF THE OHIO RIVER. WAVES OF STEADIER RAINFALL
WILL CONTINUE TO IMPACT MAINLY AREAS SOUTH OF I-70 INTO THE EVENING
AS WEAK DISTURBANCES RIDE ALONG THE BOUNDARY. ISENTROPIC LIFT AND
DEEPER MOISTURE WILL REMAIN FOCUSED OVER FAR SOUTHERN COUNTIES IN
CLOSER PROXIMITY TO THE BOUNDARY. FURTHER TO THE NORTH...INFLUENCE
OF HIGH PRESSURE MOVING THROUGH THE GREAT LAKES WILL SERVE TO LIMIT
MOISTURE IN THE LOWER LEVELS AND WITH A LACK OF SIGNIFICANT
FORCING...HAVE A HARD TIME SEEING MORE THAN LIGHT WIDELY SCATTERED
SHOWERS AT LEAST THROUGH MIDNIGHT. WILL CONTINUE TO CARRY HIGHEST
POPS IN FAR SOUTHERN COUNTIES THROUGH THE EVENING WITH CHANCE POPS
ELSEWHERE.
AS THE CENTER OF THE HIGH SHIFTS INTO QUEBEC LATE TONIGHT...MOISTURE
WILL RETURN NORTH IN RETURN FLOW ALOFT IN WAKE OF THE HIGH. AXIS OF
ISENTROPIC LIFT THROUGH ABOUT 700MB WILL LIFT INTO THE NORTHERN HALF
OF THE FORECAST AREA DURING THE SECOND HALF OF THE NIGHT...AND MAY
BE ENOUGH TO GENERATE ADDITIONAL LIGHT RAIN SHOWERS TOWARDS
DAYBREAK. WILL THEREFORE MAINTAIN CHANCE POPS ACROSS ENTIRE FORECAST
AREA AFTER MIDNIGHT. SATURATED BOUNDARY LAYER CONDITIONS WILL
MAINTAIN THICK STRATOCU DECK ALL NIGHT.
TEMPS...WITH PRESENCE OF CLOUDS...POCKETS OF PRECIP AND DEEP LOW
LEVEL MOISTURE...DO NOT EXPECT TEMPS TO FALL MUCH MORE THAN FIVE
DEGREES OR SO FROM LATE AFTERNOON READINGS. MAV GUIDANCE LOOKED
REASONABLE.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
FORECAST CHALLENGES FOCUS ON PRECIP CHANCES THROUGH TUESDAY NIGHT.
MODEL GUIDANCE HAS LARGELY SHIFTED NORTH WITH THE TRACK OF THE
SURFACE WAVE ON TUESDAY...WITH THE LOW MOVING ACROSS THE FORECAST
AREA DURING THE AFTERNOON. WITH THE UPPER TROUGH COMING IN MORE
AMPLIFIED...THE NORTHERN TRACK OF THE LOW SEEMS VERY REASONABLE.
STILL SOME MINOR TIMING DIFFERENCES BETWEEN MODELS WITH THE LOW BUT
THIS SHOULD ONLY IMPACT START AND ENDING TIMES TO THE PRECIP.
ESSENTIALLY TOOK A BLEND OF THE 12Z SUITE OF DATA.
LOOKING INCREASINGLY MORE LIKELY THAT RAIN SHOWERS WILL REMAIN
LARGELY ISOLATED ON MONDAY ACROSS MUCH OF THE AREA IN THE ABSENCE OF
ANY SIGNIFICANT APPRECIABLE FORCING. AXIS OF ISENTROPIC LIFT WILL
PULL AWAY TO THE NORTHEAST DURING THE MORNING WITH DRIER AIR ALOFT
ASSOCIATED WITH A WEAK AREA OF HIGH PRESSURE SPREADING INTO THE
REGION DURING THE AFTERNOON. WHILE SCATTERED PRECIP MAY CONTINUE TO
PERIODICALLY IMPACT FAR SOUTHERN COUNTIES IN CLOSER PROXIMITY TO THE
STALLED BOUNDARY...SHOULD BE DRIER WEATHER ELSEWHERE ON MONDAY
ONCE THE DEEPER ISENTROPIC LIFT DEPARTS. WITH MOISTURE REMAINING
TRAPPED BELOW 5-6KFT HOWEVER...SKIES WILL REMAIN CLOUDY AND THE
PRESENCE OF THE DRYING ALOFT COULD ACTUALLY PROMOTE SOME POCKETS OF
DRIZZLE. FAR SOUTHERN COUNTIES REMAIN CLOSE ENOUGH TO ELEVATED
INSTABILITY AXIS TO MAINTAIN ISOLATED THUNDER MENTION DURING THE
AFTERNOON.
FOCUS WILL TURN TO THE SURFACE WAVE DEVELOPING OVER THE SOUTHERN
PLAINS MONDAY NIGHT AS A SHARP UPPER TROUGH SHIFTS EAST OUT OF THE
ROCKIES. APPROACH OF THE WAVE WILL FORCE THE FRONT TO LIFT BACK
NORTH LATE MONDAY NIGHT WITH WIDESPREAD RAINFALL EXPANDING INTO THE
SOUTHERN HALF OF THE FORECAST AREA PRIOR TO DAYBREAK AS STRONG LOW
LEVEL JET NOSES INTO THE REGION. RAINFALL WILL EXPAND ACROSS THE
ENTIRE FORECAST AREA ON TUESDAY MORNING AS ISENTROPIC LIFT AND
FORCING ALOFT STRENGTHEN AND HELP TO ADVECT DEEP GULF MOISTURE
ACROSS CENTRAL INDIANA. PRECIPITABLE WATER VALUES RISE TO 1.2-1.4
INCHES BY THE AFTERNOON WHICH WOULD BE 250-300% OF AVERAGE VALUES
FOR THIS TIME OF YEAR. LIFT WILL BE FURTHER ENHANCED BY DIFFLUENCE
IN THE MID AND UPPER LEVELS AND CONTINUED PRESENCE OF 60KT JET AT
850MB. HAVE INCREASED TO 100 POPS OVER THE ENTIRE FORECAST AREA.
WITH MORE NORTHERN TRACK TO SURFACE LOW AND PRESENCE OF INSTABILITY
THROUGH THE BOUNDARY LAYER...HAVE ALSO INSERTED THUNDER WORDING OVER
ALL OF CENTRAL INDIANA. POTENTIAL FOR WIDESPREAD ONE TO TWO INCHES
RAINFALL TOTALS WITH ISOLATED HIGHER AMOUNTS THROUGH TUESDAY EVENING
CONSIDERING ALL OF THE ABOVE THOUGHTS. THESE AMOUNTS WILL LIKELY
CAUSE LOCALIZED NUISANCE FLOODING ALONG WITH RISES ON ARE RIVERS AND
STREAMS. HOWEVER...DO NOT ANTICIPATE WIDESPREAD FLOODING PROBLEMS.
WILL HIGHLIGHT IN HWO.
LOW WILL SHIFT INTO OHIO TUESDAY EVENING WITH PRECIP LIKELY TO
PERSIST FOR MUCH OF THE EVENING AS MID LEVEL DEFORMATION AXIS
ROTATES ACROSS THE FORECAST AREA IN WAKE OF THE LOW AND FRONT.
PRECIP WILL END LATE TUESDAY NIGHT FROM WEST TO EAST AS DRIER AIR
RAPIDLY ADVECTS INTO THE REGION. MODEL SOUNDINGS INDICATE LOW CLOUDS
MAY NOT COMPLETELY DEPART UNTIL CLOSER TO DAYBREAK WEDNESDAY.
SUNSHINE WILL RETURN FOR WEDNESDAY AS HIGH PRESSURE EXPANDS ACROSS
THE OHIO VALLEY.
TEMPS...MAVMOS GUIDANCE LOOKS REASONABLE FOR HIGHS BOTH MONDAY AND
TUESDAY CONSIDERING BOUNDARY LAYER TEMPS AND PRESENCE OF WARM
ADVECTION. MUCH OF THE AREA LIKELY TO GET INTO THE 60S TUESDAY WITH
THE LOW MOVING FURTHER NORTH. HELD CLOSE TO MOS FOR LOWS THROUGH THE
PERIOD AS WELL.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
LARGE RIDGE OF HIGH PRESSURE OVER THE AREA WILL KEEP THE WEATHER DRY
WEDNESDAY NIGHT THROUGH FRIDAY. BY FRIDAY NIGHT A DEEP UPPER TROUGH
SHOULD START TO SWING OUT THE MOUNTAINS AND INTO THE PLAINS STATES
AND START PRODUCING SOME ISENTROPIC LIFT ACROSS THE AREA AHEAD OF A
COLD FRONT...BRINGING RAIN CHANCES IN FOR FRIDAY NIGHT. ALTHOUGH
THERE AREA SOME DIFFERENCES IN THE ECMWF AND GFS WITH THE EXACT
TIMING OF THE SYSTEM...WITH THE GFS BEING FASTER AND ECMWF SLOWER
AND INDIVIDUAL ENSEMBLE MEMBERS SUPPORTING EACH SOLUTION...THE
CONSENSUS OF THE MODELS AT THIS POINT IS TO BRING IN SOME
PRECIPITATION IN THE WESTERN AREA AT LEAST ON FRIDAY NIGHT. BY
SATURDAY AND INTO SATURDAY NIGHT THIS SHOULD OVERSPREAD THE AREA AND
MODELS ARE SHOWING BOTH STRONG LIFT AND AMPLE MOISTURE...THUS KEPT
THE LIKELIES GIVEN BY THE INITIALIZATION.
HIGH TEMPERATURES WILL RUN ABOVE NORMAL IN THE MIDDLE 50S THROUGH
THE EXTENDED.
&&
.AVIATION /DISCUSSION FOR 202100Z KIND TAF UPDATE/...
STILL QUITE A BIT OF RAIN UPSTREAM OVER ILLINOIS...SO PERIODS OF
LIGHT RAIN EXPECTED AT KIND UNTIL AT LEAST 210100Z. CEILINGS AROUND
015 FAIRLY WIDESPREAD UPSTREAM...SO WILL LOWER CEILINGS TO BELOW 020
FOR THE REST OF THE AFTERNOON. MAINLY MVFR VISIBILITY RESTRICTIONS
WITHIN THE RAIN AREAS...AS IT APPEARS THE HEAVIER RAIN AREAS WILL
REMAIN SOUTH OF KIND. PREVIOUS DISCUSSION FOLLOWS.
AT 17Z THE COLD FRONT HAS MOVED THROUGH THE SITES AND WINDS HAVE
SHIFTED TO NORTHWESTERLY AND THEN NORTHERLY. RAIN WILL CONTINUE FOR
THE MOST PART OVER KBMG FOR THE REMAINDER OF THE AFTERNOON BASED ON
UPSTREAM OBSERVATIONS...AND THE IFR OR LOWER CONDITIONS MAY NOT
IMPROVE. COULD SEE A BRIEF RISE TO MVFR THIS EVENING BUT UNCERTAINTY
FAIRLY HIGH. TIME HEIGHTS AND EXTRAPOLATION OF CURRENT CONDITIONS
INDICATE KIND AND KHUF WILL MAINLY SEE MVFR CEILINGS FOR THE REST OF
THE AFTERNOON AND TONIGHT BEFORE DROPPING TO IFR NEAR DAYBREAK
TOMORROW. WHILE RUC AND RADAR MOSAIC INDICATE SOME POTENTIAL FOR
SHOWERS AT THESE SITES...THE SPOTTY AND LIGHT NATURE OF THESE MEANS
WILL ONLY INCLUDE A VCSH FOR THE NEXT FEW HOURS AND NOT AN EXPLICIT
MENTION. UP AT KLAF COULD SEE SEVERAL HOURS OF VFR BEFORE DROPPING
TO MVFR OVERNIGHT BEING FURTHER AWAY FROM THE FORCING. WINDS WILL
VEER OVERNIGHT TO BE EASTERLY IN THE MORNING.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...RYAN
NEAR TERM...RYAN
SHORT TERM...RYAN
LONG TERM....CP
AVIATION...CP/JAS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
328 PM EST SUN NOV 20 2011
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
THE ACTIVE WEATHER PATTERN WILL BEGIN TODAY AS A COLD FRONT SLIDES
ACROSS CENTRAL INDIANA TRIGGERING THE FIRST PRECIP IN SEVERAL
DAYS. THIS FRONT WILL STALL OUT NEAR THE OHIO RIVER TONIGHT...
CONTINUING TO GENERATE RAINFALL OVER THE SOUTHERN HALF OF FORECAST
AREA THROUGH MID-WEEK. A REINFORCING LOW WILL TRAVEL ALONG THE
FRONTAL BOUNDARY ON TUESDAY BRINGING A CHANCE FOR ISOLATED
THUNDERSTORMS TO THE SOUTHERN COUNTIES.
&&
.NEAR TERM /REST OF TODAY/...
COLD FRONT MAKING STEADY SOUTHWARD PROGRESS ACROSS THE FORECAST
AREA THIS MORNING...AND AS OF 16Z WAS LOCATED ROUGHLY FROM
VINCENNES E/NE TO JUST SOUTH OF BLOOMINGTON AND SHELBYVILLE.
PRECIP WAS EXPANDING IN COVERAGE ACROSS THE SOUTHERN HALF OF THE
FORECAST AREA. TEMPERATURES WERE IN THE 40S NORTH AND WEST OF
INDIANAPOLIS WITH MAINLY 50S ELSEWHERE LATE THIS MORNING.
ADJUSTMENTS TO FORECAST FOR THE REST OF THE DAY FOCUSING ON TEMPS
AND PRECIP CHANCES. HAVE TRENDED MORE WITH THE RUC FOR THE
AFTERNOON AS 12Z NAM ALREADY STRUGGLING WITH NORTHWARD EXTENT TO
PRECIP SHIELD. WAVE OF LOW PRESSURE OVER NORTHEAST ARKANSAS WILL
TRAVERSE THE BOUNDARY THROUGH THE AFTERNOON AS THE FRONT SETTLES
NEAR THE OHIO RIVER BY LATE DAY. RAIN WILL CONTINUE TO EXPAND IN
COVERAGE ACROSS MUCH OF THE AREA ALONG AND SOUTH OF I-70 WITH
INCREASE IN LOW LEVEL MOISTURE AND ISENTROPIC LIFT PRESENT ACROSS
SOUTHERN HALF OF INDIANA. HAVE INCREASED TO LIKELY POPS ALL THE
WAY NORTH TO THE I-70 CORRIDOR WITH CATEGORICAL POPS OVER FAR
SOUTHERN COUNTIES IN CLOSEST PROXIMITY TO THE SOUTHWARD-MOVING
BOUNDARY. SHOULD BE A FAIRLY SHARP CUTOFF TO LIGHT PRECIP FURTHER
NORTH ACROSS FORECAST AREA AS LAYER OF LOW LEVEL MOISTURE BECOMES
SHALLOWER WITH GREATER PRESENCE OF DRIER AIR ALOFT.
HIGH TEMPS HAVE BEEN REACHED ALREADY TODAY FOR MUCH OF THE
FORECAST AREA. WITH SUBTLE COLD ADVECTION COMBINING WITH AN
ABUNDANCE OF LOW CLOUDS AND PRECIP FOR MOST LOCATIONS...
ANTICIPATE TEMPS WILL REMAIN STEADY OR SLOWLY FALL THROUGH THE
AFTERNOON. ONLY EXCEPTION TO THIS LIKELY TO BE OVER NORTHWEST
COUNTIES WHERE FRONTAL PASSAGE AND INITIAL TEMP DROP OCCURRED
AROUND DAYBREAK. MAY SEE CURRENT TEMPS IN MID 40S MANAGE TO WARM A
FEW DEGREES THROUGH THE AFTERNOON...PARTICULARLY WITH LESS
COVERAGE TO STRATOCU IN THESE AREAS. TOOK A BLEND OF OBSERVATIONS
SO FAR THIS MORNING AND RUC TEMP DATA TO CONSTITUTE THE NON-
DIURNAL SPREAD FOR THE REST OF THE DAY.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
THE MAIN FOCUS OF THE SHORT TERM IS CONTINUED RAIN AND
THUNDERSTORM POTENTIAL ON TUESDAY.
COLD FRONT WILL BE THROUGH CENTRAL INDIANA BY THIS EVENING AND
WILL STALL OUT NEAR THE OHIO RIVER TONIGHT. THIS WILL RESULT IN
CONTINUED RAINFALL OVER THE SOUTHERN HALF OF FORECAST AREA THROUGH
TUESDAY. THAT PORTION OF FORECAST AREA COULD PICK UP 2 TO 3 INCHES
OF RAINFALL BY THE END OF ALL OF THIS...POSSIBLY CREATING SOME SMALL
STREAM AND URBAN FLOODING PROBLEMS. IN REGARD TO THUNDERSTORMS FOR
TOMORROW...INSTABILITY IS NOT SUFFICIENT ENOUGH TO ADD MENTION OF
THUNDERSTORMS AT THIS TIME.
TUESDAY...A SURFACE LOW WILL MOVE ALONG THE STALLED FRONTAL
BOUNDARY BRINGING YET ANOTHER ROUND OF PRECIP...AGAIN MAINLY OVER
THE SOUTHERN PORTIONS OF FORECAST AREA. THIS SETUP LOOKS MORE
FAVORABLE THOUGH FOR THUNDERSTORMS ACROSS THE SOUTHERN COUNTIES AS
STRONG WARM ADVECTION AHEAD OF IT SPREADS ACROSS CENTRAL INDIANA.
INSTABILITY WILL INCREASE IN THIS WARM SECTOR WITH CAPES RANGING
FROM 500-1000J/KG. SURFACE LOW WILL MOVE THROUGH DURING PRIME
HOURS OF DAY...LATE AFTERNOON GENERATING ISOLATED THUNDERSTORMS
OVER SOUTHERN PORTIONS OF CENTRAL INDIANA.
TEMPS...WAS ABLE TO GO WITH A BLEND THROUGH MOST OF THE SHORT
TERM...EXCEPT FOR MONDAY NIGHT WHEN THE NAM TRENDED MUCH WARMER
THAN THE GFS. LIKED THE NAM DUE TO THE OVERCAST SKIES. ALSO LEANED
TOWARD THE WARMER SIDE OF GUIDANCE THROUGH MOST OF SHORT
TERM FOR DAYTIME HIGHS...ESPECIALLY ON TUESDAY WHEN SOUTHWEST FLOW IS
STRONGEST AHEAD OF SECOND SURFACE LOW.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
DRY WEATHER AND MODERATING TEMPERATURES SHOULD CHARACTERIZE THE
BEGINNING OF THE LONG TERM AND THROUGH FRIDAY AS HIGH PRESSURE
SLIDES EAST ACROSS THE OHIO VALLEY WEDNESDAY INTO THURSDAY FOLLOWED
BY ANOTHER ROUND OF STRONG RETURN FLOW WARM AIR ADVECTION AHEAD OF
AN APPROACHING COLD FRONT. THEN...SHOWER CHANCES WILL BE INCREASING
AHEAD OF A COLD FRONT THAT IS EXPECTED TO MOVE THROUGH ON SATURDAY.
THE 00Z OPERATIONAL GFS CONTINUES TO START OFF FASTER REGARDING HIGH
PRESSURE MOVING EAST ACROSS THE OHIO VALLEY AND THEN THE
APPALACHIANS. AFTER THAT...THE MODELS ALSO HAVE SOME DIFFERENCES
REGARDING THE LOCATIONS OF CENTERS OF SURFACE LOW PRESSURE ALONG AN
APPROACHING FRONTAL SYSTEM. HOWEVER...MODELS ARE CLOSE IN TIMING
REGARDING THE FRONTAL POSITION AND ASSOCIATED QPF WITH THE SYSTEM
WHICH JIVES WELL WITH THE INITIALIZATION EXTENDED...SO WILL LEAVE
POPS ALONE WITH WEDNESDAY THROUGH FRIDAY DRY AND CHANCE POPS FRIDAY
NIGHT AND SATURDAY.
TEMPERATURES WILL START OUT AROUND NORMAL ON WEDNESDAY IN THE UPPER
40S AND LOWER 50S BEFORE CLIMBING TO ABOVE NORMAL MOSTLY IN THE MID
AND UPPER 50S THE REMAINDER OF THE EXTENDED.
&&
.AVIATION /DISCUSSION FOR 202100Z KIND TAF UPDATE/...
STILL QUITE A BIT OF RAIN UPSTREAM OVER ILLINOIS...SO PERIODS OF
LIGHT RAIN EXPECTED AT KIND UNTIL AT LEAST 210100Z. CEILINGS AROUND
015 FAIRLY WIDESPREAD UPSTREAM...SO WILL LOWER CEILINGS TO BELOW 020
FOR THE REST OF THE AFTERNOON. MAINLY MVFR VISIBILITY RESTRICTIONS
WITHIN THE RAIN AREAS...AS IT APPEARS THE HEAVIER RAIN AREAS WILL
REMAIN SOUTH OF KIND. PREVIOUS DISCUSSION FOLLOWS.
AT 17Z THE COLD FRONT HAS MOVED THROUGH THE SITES AND WINDS HAVE
SHIFTED TO NORTHWESTERLY AND THEN NORTHERLY. RAIN WILL CONTINUE FOR
THE MOST PART OVER KBMG FOR THE REMAINDER OF THE AFTERNOON BASED ON
UPSTREAM OBSERVATIONS...AND THE IFR OR LOWER CONDITIONS MAY NOT
IMPROVE. COULD SEE A BRIEF RISE TO MVFR THIS EVENING BUT UNCERTAINTY
FAIRLY HIGH. TIME HEIGHTS AND EXTRAPOLATION OF CURRENT CONDITIONS
INDICATE KIND AND KHUF WILL MAINLY SEE MVFR CEILINGS FOR THE REST OF
THE AFTERNOON AND TONIGHT BEFORE DROPPING TO IFR NEAR DAYBREAK
TOMORROW. WHILE RUC AND RADAR MOSAIC INDICATE SOME POTENTIAL FOR
SHOWERS AT THESE SITES...THE SPOTTY AND LIGHT NATURE OF THESE MEANS
WILL ONLY INCLUDE A VCSH FOR THE NEXT FEW HOURS AND NOT AN EXPLICIT
MENTION. UP AT KLAF COULD SEE SEVERAL HOURS OF VFR BEFORE DROPPING
TO MVFR OVERNIGHT BEING FURTHER AWAY FROM THE FORCING. WINDS WILL
VEER OVERNIGHT TO BE EASTERLY IN THE MORNING.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...CP/JAS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1203 PM EST SUN NOV 20 2011
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
THE ACTIVE WEATHER PATTERN WILL BEGIN TODAY AS A COLD FRONT SLIDES
ACROSS CENTRAL INDIANA TRIGGERING THE FIRST PRECIP IN SEVERAL
DAYS. THIS FRONT WILL STALL OUT NEAR THE OHIO RIVER TONIGHT...
CONTINUING TO GENERATE RAINFALL OVER THE SOUTHERN HALF OF FORECAST
AREA THROUGH MID-WEEK. A REINFORCING LOW WILL TRAVEL ALONG THE
FRONTAL BOUNDARY ON TUESDAY BRINGING A CHANCE FOR ISOLATED
THUNDERSTORMS TO THE SOUTHERN COUNTIES.
&&
.NEAR TERM /REST OF TODAY/...
COLD FRONT MAKING STEADY SOUTHWARD PROGRESS ACROSS THE FORECAST
AREA THIS MORNING...AND AS OF 16Z WAS LOCATED ROUGHLY FROM
VINCENNES E/NE TO JUST SOUTH OF BLOOMINGTON AND SHELBYVILLE.
PRECIP WAS EXPANDING IN COVERAGE ACROSS THE SOUTHERN HALF OF THE
FORECAST AREA. TEMPERATURES WERE IN THE 40S NORTH AND WEST OF
INDIANAPOLIS WITH MAINLY 50S ELSEWHERE LATE THIS MORNING.
ADJUSTMENTS TO FORECAST FOR THE REST OF THE DAY FOCUSING ON TEMPS
AND PRECIP CHANCES. HAVE TRENDED MORE WITH THE RUC FOR THE
AFTERNOON AS 12Z NAM ALREADY STRUGGLING WITH NORTHWARD EXTENT TO
PRECIP SHIELD. WAVE OF LOW PRESSURE OVER NORTHEAST ARKANSAS WILL
TRAVERSE THE BOUNDARY THROUGH THE AFTERNOON AS THE FRONT SETTLES
NEAR THE OHIO RIVER BY LATE DAY. RAIN WILL CONTINUE TO EXPAND IN
COVERAGE ACROSS MUCH OF THE AREA ALONG AND SOUTH OF I-70 WITH
INCREASE IN LOW LEVEL MOISTURE AND ISENTROPIC LIFT PRESENT ACROSS
SOUTHERN HALF OF INDIANA. HAVE INCREASED TO LIKELY POPS ALL THE
WAY NORTH TO THE I-70 CORRIDOR WITH CATEGORICAL POPS OVER FAR
SOUTHERN COUNTIES IN CLOSEST PROXIMITY TO THE SOUTHWARD-MOVING
BOUNDARY. SHOULD BE A FAIRLY SHARP CUTOFF TO LIGHT PRECIP FURTHER
NORTH ACROSS FORECAST AREA AS LAYER OF LOW LEVEL MOISTURE BECOMES
SHALLOWER WITH GREATER PRESENCE OF DRIER AIR ALOFT.
HIGH TEMPS HAVE BEEN REACHED ALREADY TODAY FOR MUCH OF THE
FORECAST AREA. WITH SUBTLE COLD ADVECTION COMBINING WITH AN
ABUNDANCE OF LOW CLOUDS AND PRECIP FOR MOST LOCATIONS...
ANTICIPATE TEMPS WILL REMAIN STEADY OR SLOWLY FALL THROUGH THE
AFTERNOON. ONLY EXCEPTION TO THIS LIKELY TO BE OVER NORTHWEST
COUNTIES WHERE FRONTAL PASSAGE AND INITIAL TEMP DROP OCCURRED
AROUND DAYBREAK. MAY SEE CURRENT TEMPS IN MID 40S MANAGE TO WARM A
FEW DEGREES THROUGH THE AFTERNOON...PARTICULARLY WITH LESS
COVERAGE TO STRATOCU IN THESE AREAS. TOOK A BLEND OF OBSERVATIONS
SO FAR THIS MORNING AND RUC TEMP DATA TO CONSTITUTE THE NON-
DIURNAL SPREAD FOR THE REST OF THE DAY.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
THE MAIN FOCUS OF THE SHORT TERM IS CONTINUED RAIN AND
THUNDERSTORM POTENTIAL ON TUESDAY.
COLD FRONT WILL BE THROUGH CENTRAL INDIANA BY THIS EVENING AND
WILL STALL OUT NEAR THE OHIO RIVER TONIGHT. THIS WILL RESULT IN
CONTINUED RAINFALL OVER THE SOUTHERN HALF OF FORECAST AREA THROUGH
TUESDAY. THAT PORTION OF FORECAST AREA COULD PICK UP 2 TO 3 INCHES
OF RAINFALL BY THE END OF ALL OF THIS...POSSIBLY CREATING SOME SMALL
STREAM AND URBAN FLOODING PROBLEMS. IN REGARD TO THUNDERSTORMS FOR
TOMORROW...INSTABILITY IS NOT SUFFICIENT ENOUGH TO ADD MENTION OF
THUNDERSTORMS AT THIS TIME.
TUESDAY...A SURFACE LOW WILL MOVE ALONG THE STALLED FRONTAL
BOUNDARY BRINGING YET ANOTHER ROUND OF PRECIP...AGAIN MAINLY OVER
THE SOUTHERN PORTIONS OF FORECAST AREA. THIS SETUP LOOKS MORE
FAVORABLE THOUGH FOR THUNDERSTORMS ACROSS THE SOUTHERN COUNTIES AS
STRONG WARM ADVECTION AHEAD OF IT SPREADS ACROSS CENTRAL INDIANA.
INSTABILITY WILL INCREASE IN THIS WARM SECTOR WITH CAPES RANGING
FROM 500-1000J/KG. SURFACE LOW WILL MOVE THROUGH DURING PRIME
HOURS OF DAY...LATE AFTERNOON GENERATING ISOLATED THUNDERSTORMS
OVER SOUTHERN PORTIONS OF CENTRAL INDIANA.
TEMPS...WAS ABLE TO GO WITH A BLEND THROUGH MOST OF THE SHORT
TERM...EXCEPT FOR MONDAY NIGHT WHEN THE NAM TRENDED MUCH WARMER
THAN THE GFS. LIKED THE NAM DUE TO THE OVERCAST SKIES. ALSO LEANED
TOWARD THE WARMER SIDE OF GUIDANCE THROUGH MOST OF SHORT
TERM FOR DAYTIME HIGHS...ESPECIALLY ON TUESDAY WHEN SOUTHWEST FLOW IS
STRONGEST AHEAD OF SECOND SURFACE LOW.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
DRY WEATHER AND MODERATING TEMPERATURES SHOULD CHARACTERIZE THE
BEGINNING OF THE LONG TERM AND THROUGH FRIDAY AS HIGH PRESSURE
SLIDES EAST ACROSS THE OHIO VALLEY WEDNESDAY INTO THURSDAY FOLLOWED
BY ANOTHER ROUND OF STRONG RETURN FLOW WARM AIR ADVECTION AHEAD OF
AN APPROACHING COLD FRONT. THEN...SHOWER CHANCES WILL BE INCREASING
AHEAD OF A COLD FRONT THAT IS EXPECTED TO MOVE THROUGH ON SATURDAY.
THE 00Z OPERATIONAL GFS CONTINUES TO START OFF FASTER REGARDING HIGH
PRESSURE MOVING EAST ACROSS THE OHIO VALLEY AND THEN THE
APPALACHIANS. AFTER THAT...THE MODELS ALSO HAVE SOME DIFFERENCES
REGARDING THE LOCATIONS OF CENTERS OF SURFACE LOW PRESSURE ALONG AN
APPROACHING FRONTAL SYSTEM. HOWEVER...MODELS ARE CLOSE IN TIMING
REGARDING THE FRONTAL POSITION AND ASSOCIATED QPF WITH THE SYSTEM
WHICH JIVES WELL WITH THE INITIALIZATION EXTENDED...SO WILL LEAVE
POPS ALONE WITH WEDNESDAY THROUGH FRIDAY DRY AND CHANCE POPS FRIDAY
NIGHT AND SATURDAY.
TEMPERATURES WILL START OUT AROUND NORMAL ON WEDNESDAY IN THE UPPER
40S AND LOWER 50S BEFORE CLIMBING TO ABOVE NORMAL MOSTLY IN THE MID
AND UPPER 50S THE REMAINDER OF THE EXTENDED.
&&
.AVIATION /DISCUSSION FOR 20/18Z TAF ISSUANCE/...
AT 17Z THE COLD FRONT HAS MOVED THROUGH THE SITES AND WINDS HAVE
SHIFTED TO NORTHWESTERLY AND THEN NORTHERLY. RAIN WILL CONTINUE FOR
THE MOST PART OVER KBMG FOR THE REMAINDER OF THE AFTERNOON BASED ON
UPSTREAM OBSERVATIONS...AND THE IFR OR LOWER CONDITIONS MAY NOT
IMPROVE. COULD SEE A BRIEF RISE TO MVFR THIS EVENING BUT UNCERTAINTY
FAIRLY HIGH. TIME HEIGHTS AND EXTRAPOLATION OF CURRENT CONDITIONS
INDICATE KIND AND KHUF WILL MAINLY SEE MVFR CEILINGS FOR THE REST OF
THE AFTERNOON AND TONIGHT BEFORE DROPPING TO IFR NEAR DAYBREAK
TOMORROW. WHILE RUC AND RADAR MOSAIC INDICATE SOME POTENTIAL FOR
SHOWERS AT THESE SITES...THE SPOTTY AND LIGHT NATURE OF THESE MEANS
WILL ONLY INCLUDE A VCSH FOR THE NEXT FEW HOURS AND NOT AN EXPLICIT
MENTION. UP AT KLAF COULD SEE SEVERAL HOURS OF VFR BEFORE DROPPING
TO MVFR OVERNIGHT BEING FURTHER AWAY FROM THE FORCING. WINDS WILL
VEER OVERNIGHT TO BE EASTERLY IN THE MORNING.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...CP
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1105 AM EST SUN NOV 20 2011
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
THE ACTIVE WEATHER PATTERN WILL BEGIN TODAY AS A COLD FRONT SLIDES
ACROSS CENTRAL INDIANA TRIGGERING THE FIRST PRECIP IN SEVERAL
DAYS. THIS FRONT WILL STALL OUT NEAR THE OHIO RIVER TONIGHT...
CONTINUING TO GENERATE RAINFALL OVER THE SOUTHERN HALF OF FORECAST
AREA THROUGH MID-WEEK. A REINFORCING LOW WILL TRAVEL ALONG THE
FRONTAL BOUNDARY ON TUESDAY BRINGING A CHANCE FOR ISOLATED
THUNDERSTORMS TO THE SOUTHERN COUNTIES.
&&
.NEAR TERM /REST OF TODAY/...
COLD FRONT MAKING STEADY SOUTHWARD PROGRESS ACROSS THE FORECAST
AREA THIS MORNING...AND AS OF 16Z WAS LOCATED ROUGHLY FROM
VINCENNES E/NE TO JUST SOUTH OF BLOOMINGTON AND SHELBYVILLE.
PRECIP WAS EXPANDING IN COVERAGE ACROSS THE SOUTHERN HALF OF THE
FORECAST AREA. TEMPERATURES WERE IN THE 40S NORTH AND WEST OF
INDIANAPOLIS WITH MAINLY 50S ELSEWHERE LATE THIS MORNING.
ADJUSTMENTS TO FORECAST FOR THE REST OF THE DAY FOCUSING ON TEMPS
AND PRECIP CHANCES. HAVE TRENDED MORE WITH THE RUC FOR THE
AFTERNOON AS 12Z NAM ALREADY STRUGGLING WITH NORTHWARD EXTENT TO
PRECIP SHIELD. WAVE OF LOW PRESSURE OVER NORTHEAST ARKANSAS WILL
TRAVERSE THE BOUNDARY THROUGH THE AFTERNOON AS THE FRONT SETTLES
NEAR THE OHIO RIVER BY LATE DAY. RAIN WILL CONTINUE TO EXPAND IN
COVERAGE ACROSS MUCH OF THE AREA ALONG AND SOUTH OF I-70 WITH
INCREASE IN LOW LEVEL MOISTURE AND ISENTROPIC LIFT PRESENT ACROSS
SOUTHERN HALF OF INDIANA. HAVE INCREASED TO LIKELY POPS ALL THE
WAY NORTH TO THE I-70 CORRIDOR WITH CATEGORICAL POPS OVER FAR
SOUTHERN COUNTIES IN CLOSEST PROXIMITY TO THE SOUTHWARD-MOVING
BOUNDARY. SHOULD BE A FAIRLY SHARP CUTOFF TO LIGHT PRECIP FURTHER
NORTH ACROSS FORECAST AREA AS LAYER OF LOW LEVEL MOISTURE BECOMES
SHALLOWER WITH GREATER PRESENCE OF DRIER AIR ALOFT.
HIGH TEMPS HAVE BEEN REACHED ALREADY TODAY FOR MUCH OF THE
FORECAST AREA. WITH SUBTLE COLD ADVECTION COMBINING WITH AN
ABUNDANCE OF LOW CLOUDS AND PRECIP FOR MOST LOCATIONS...
ANTICIPATE TEMPS WILL REMAIN STEADY OR SLOWLY FALL THROUGH THE
AFTERNOON. ONLY EXCEPTION TO THIS LIKELY TO BE OVER NORTHWEST
COUNTIES WHERE FRONTAL PASSAGE AND INITIAL TEMP DROP OCCURRED
AROUND DAYBREAK. MAY SEE CURRENT TEMPS IN MID 40S MANAGE TO WARM A
FEW DEGREES THROUGH THE AFTERNOON...PARTICULARLY WITH LESS
COVERAGE TO STRATOCU IN THESE AREAS. TOOK A BLEND OF OBSERVATIONS
SO FAR THIS MORNING AND RUC TEMP DATA TO CONSTITUTE THE NON-
DIURNAL SPREAD FOR THE REST OF THE DAY.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
THE MAIN FOCUS OF THE SHORT TERM IS CONTINUED RAIN AND
THUNDERSTORM POTENTIAL ON TUESDAY.
COLD FRONT WILL BE THROUGH CENTRAL INDIANA BY THIS EVENING AND
WILL STALL OUT NEAR THE OHIO RIVER TONIGHT. THIS WILL RESULT IN
CONTINUED RAINFALL OVER THE SOUTHERN HALF OF FORECAST AREA THROUGH
TUESDAY. THAT PORTION OF FORECAST AREA COULD PICK UP 2 TO 3 INCHES
OF RAINFALL BY THE END OF ALL OF THIS...POSSIBLY CREATING SOME SMALL
STREAM AND URBAN FLOODING PROBLEMS. IN REGARD TO THUNDERSTORMS FOR
TOMORROW...INSTABILITY IS NOT SUFFICIENT ENOUGH TO ADD MENTION OF
THUNDERSTORMS AT THIS TIME.
TUESDAY...A SURFACE LOW WILL MOVE ALONG THE STALLED FRONTAL
BOUNDARY BRINGING YET ANOTHER ROUND OF PRECIP...AGAIN MAINLY OVER
THE SOUTHERN PORTIONS OF FORECAST AREA. THIS SETUP LOOKS MORE
FAVORABLE THOUGH FOR THUNDERSTORMS ACROSS THE SOUTHERN COUNTIES AS
STRONG WARM ADVECTION AHEAD OF IT SPREADS ACROSS CENTRAL INDIANA.
INSTABILITY WILL INCREASE IN THIS WARM SECTOR WITH CAPES RANGING
FROM 500-1000J/KG. SURFACE LOW WILL MOVE THROUGH DURING PRIME
HOURS OF DAY...LATE AFTERNOON GENERATING ISOLATED THUNDERSTORMS
OVER SOUTHERN PORTIONS OF CENTRAL INDIANA.
TEMPS...WAS ABLE TO GO WITH A BLEND THROUGH MOST OF THE SHORT
TERM...EXCEPT FOR MONDAY NIGHT WHEN THE NAM TRENDED MUCH WARMER
THAN THE GFS. LIKED THE NAM DUE TO THE OVERCAST SKIES. ALSO LEANED
TOWARD THE WARMER SIDE OF GUIDANCE THROUGH MOST OF SHORT
TERM FOR DAYTIME HIGHS...ESPECIALLY ON TUESDAY WHEN SOUTHWEST FLOW IS
STRONGEST AHEAD OF SECOND SURFACE LOW.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
DRY WEATHER AND MODERATING TEMPERATURES SHOULD CHARACTERIZE THE
BEGINNING OF THE LONG TERM AND THROUGH FRIDAY AS HIGH PRESSURE
SLIDES EAST ACROSS THE OHIO VALLEY WEDNESDAY INTO THURSDAY FOLLOWED
BY ANOTHER ROUND OF STRONG RETURN FLOW WARM AIR ADVECTION AHEAD OF
AN APPROACHING COLD FRONT. THEN...SHOWER CHANCES WILL BE INCREASING
AHEAD OF A COLD FRONT THAT IS EXPECTED TO MOVE THROUGH ON SATURDAY.
THE 00Z OPERATIONAL GFS CONTINUES TO START OFF FASTER REGARDING HIGH
PRESSURE MOVING EAST ACROSS THE OHIO VALLEY AND THEN THE
APPALACHIANS. AFTER THAT...THE MODELS ALSO HAVE SOME DIFFERENCES
REGARDING THE LOCATIONS OF CENTERS OF SURFACE LOW PRESSURE ALONG AN
APPROACHING FRONTAL SYSTEM. HOWEVER...MODELS ARE CLOSE IN TIMING
REGARDING THE FRONTAL POSITION AND ASSOCIATED QPF WITH THE SYSTEM
WHICH JIVES WELL WITH THE INITIALIZATION EXTENDED...SO WILL LEAVE
POPS ALONE WITH WEDNESDAY THROUGH FRIDAY DRY AND CHANCE POPS FRIDAY
NIGHT AND SATURDAY.
TEMPERATURES WILL START OUT AROUND NORMAL ON WEDNESDAY IN THE UPPER
40S AND LOWER 50S BEFORE CLIMBING TO ABOVE NORMAL MOSTLY IN THE MID
AND UPPER 50S THE REMAINDER OF THE EXTENDED.
&&
.AVIATION /DISCUSSION FOR 20/12Z TAF ISSUANCE/...
AT 14Z THE COLD FRONT HAS TRAVELLED THROUGH ALL SITES BUT KBMG...AND
IS CURRENTLY ON THE DOORSTEP THERE. FOR THIS UPDATE ADDED RAIN TO
KBMG NOW AND LOWERED KIND TO IFR BASED ON CURRENT CONDITIONS THAT
COULD LAST FOR THE NEXT COUPLE OF HOURS UNTIL THE FRONT GETS FURTHER
SOUTH. PREVIOUS DISCUSSION FOLLOWS...
THE FRONT IS THEN EXPECTED TO STALL NEAR THE OHIO RIVER
TONIGHT. THUS...THERE SHOULD BE A SHARP CUTOFF WITH THE RAIN WITH
BMG HAVING THE HIGHEST CHANCES. SO...WENT -RA THERE THROUGH THE
DAY...VCSH AT IND AND HUF AND NOTHING AT LAF. LAF SHOULD ALSO SEE
VFR CONDITIONS BY 18Z WITH HUF AND IND NOT SEEING VFR TIL 23Z OR
LATER AND BMG LIKELY REMAINING MVFR THROUGH THE TAF PERIOD. HUF AND
IND SHOULD AGAIN BECOME MVFR TOWARD DAYBREAK TONIGHT AS A WAVE
SLIDES NORTHEAST ALONG THE FRONT.
WINDS WILL BECOME NORTHWEST AND THEN NORTH BEHIND THE FRONT THROUGH
THE MORNING HOURS AND FINALLY EAST OVERNIGHT.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...MK/CP
AREA FORECAST DISCUSSION
NWS TOPEKA KS
250 PM CST SUN NOV 20 2011
.DISCUSSION...
SURFACE RIDGING AND CLOUD COVER HAVE PREVENT TEMPS FROM WARMING UP
MUCH THIS AFTERNOON. 20Z SURFACE OBS CONTINUE TO SHOW COLD AIR
ADVECTING FROM THE NORTH WITH THE CENTER OF THE RIDGE OVER SOUTHERN
MN. ALOFT...WATER VAPOR SHOWS A CLOSED LOW OVER THE CA COAST AND
PROFILER DATA INDICATES A FAST SOUTHWEST FLOW OVER THE FORECAST AREA
WITH NO OBVIOUS WAVE WITHIN THE FLOW. HOWEVER THE RUC AND NAM
INDICATE A WEAK WAVE AT 700 MB MOVING ACROSS NORTHEAST KANSAS LATE
THIS AFTERNOON AND THIS EVENING. THIS MAY BE THE CAUSE OF THE
ENHANCED CLOUD COVER AND WEAK ECHOS ON RADAR ACROSS WESTERN KS.
THINK THAT THIS WILL NOT AMOUNT TO MUCH FOR TONIGHT DUE TO MID LEVEL
DRY AIR. MODELS SHOW THIS PASSING EAST WITH GENERAL SUBSIDENCE
TAKING OVER FOR MUCH OF THE NIGHT. ADDITIONALLY ISENTROPIC SURFACES
ARE NOT SHOWING MUCH LIFT EITHER. THEREFORE WILL CONTINUE WITH A DRY
FORECAST. CLOUD COVER COULD BE A LITTLE TRICKY TONIGHT AND HAVE A
LARGE EFFECT ON MIN TEMPS. THERE IS A GENERAL CONSENSUS THAT THE LOW
LEVEL RH OVER SOUTHERN MO AND SOUTHEAST KS WILL LIFT NORTH THROUGH
NORTHEAST KS OVERNIGHT. MEANWHILE SKIES COULD BECOME MOSTLY CLEAR
OVER CENTRAL KS. WITH THIS IN MIND HAVE DROPPED LOWS INTO THE LOWER
20S FROM MHK WEST AND LEFT LOWS IN THE LOWER 30S OVER FAR EASTERN KS
WHERE LOW CLOUDS ARE LIKELY TO HANG IN A LITTLE LONGER. FOR MONDAY
THINK TEMPS WILL WARM INTO THE MID 40S DUE TO NEUTRAL TEMP ADVECTION
AND SOME INSOLATION DURING THE DAY. MID LEVEL MOISTURE IS EXPECTED
TO BEGIN ADVECTING NORTH BY MONDAY AFTERNOON AS THE CLOSED LOW ON
THE WEST COAST MAKES ITS WAY OVER THE SOUTHERN ROCKIES. HAVE
INCLUDED SOME SLIGHT CHANCE POPS SOUTH OF I-70 DURING THE AFTERNOON
BECAUSE OF THIS.
WOLTERS
UPPER WAVE CONTINUES EAST AND NORTHEAST WHILE DEEPENING MONDAY
NIGHT. UPPER JET STREAKS FLANKING THE AREA TO THE NORTHEAST AND
SOUTHWEST INTO THE EVENING WITH DRY SLOT WORKING THROUGH SOUTHERN
KANSAS AND SOMEWHAT OF A WEAK TROWAL POKING INTO NORTHEAST KANSAS.
THERE REMAINS SOME DIFFERENCES ON THE TIMING OF THE SYSTEM WITH THE
12Z NAM ON THE FASTER END...BUT STILL APPEARS LATE EVENING THROUGH
EARLY MORNING TUESDAY WILL BE ON THE WET SIDE. DRY SLOT WILL HELP
AID CONVECTIVE CHANCES AND INSTABILITY STILL ENOUGH FOR THUNDER
INCLUSION FOR MUCH OF THE AREA. ALSO SOME CONCERN FOR FREEZING
PRECIP LATE IN THE EVENT AS SURFACE LOW PRESSURE MOVES THROUGH
SOUTHERN MISSOURI AND NORTH WINDS TAKE HOLD. WILL INTRODUCE A
FREEZING RAIN MENTION IN THE NORTHWEST. TUESDAY AFTERNOON AND NIGHT
BRING RAPIDLY IMPROVING CONDITIONS AS UPPER RIDGING BUILDS IN.
AIRMASS BEHIND THE SYSTEM NOT TERRIBLY COLD WITH DOWNSLOPE WINDS TO
THE NORTHWEST SO HIGHS SHOULD STILL REACH THE LOWER 50S TUESDAY AND
ON INTO THE UPPER 50S WEDNESDAY UNDER CLEAR SKIES AND INCREASING
SOUTH WINDS.
65
EXTENDED FORECAST (WEDNESDAY NIGHT THROUGH SUNDAY)
SOUTHERLY FLOW...WARM AIR ADVECTION AND UPPER LEVEL RIDGING WILL
RETURN TO THE CENTRAL U.S. ON THANKSGIVING DAY. HIGH TEMPERATURES
ARE EXPECTED TO QUICKLY REBOUND INTO THE LOW 60S. SOUTH WINDS WILL
BE STRONG AND GUSTY ON THANKSGIVING DAY WITH A STRONG PRESSURE
GRADIENT BETWEEN A SURFACE HIGH OVER THE SOUTHEASTERN U.S. AND
SURFACE LOW FORMING ALONG THE ROCKY MOUNTAINS. MODELS ARE INDICATING
A LONGWAVE TROUGH WILL MOVE OUT OF THE ROCKY MOUNTAINS ON FRIDAY
ALONG WITH THE SURFACE LOW AND COLD FRONT. ENOUGH ELEVATED
INSTABILITY WILL EXIST AHEAD OF THE APPROACHING FRONT FOR A FEW
THUNDERSTORMS DURING THE DAY ON FRIDAY.
MODELS QUICKLY DIVERGE INTO NEXT WEEKEND. THE OPERATIONAL GFS AND
DGEX BRING THE COLD FRONT THROUGH THE CWA FRIDAY NIGHT AND THEN
CLOSE OFF AN UPPER LEVEL LOW OVER THE MID-MISSISSIPPI RIVER VALLEY.
THE 12Z ECMWF BRINGS THE FRONT THROUGH THE CWA SATURDAY MORNING BUT
THEN CLOSES THE UPPER LEVEL LOW OFF IN NORTHEASTERN OKLAHOMA. THE
ECMWF SOLUTION WOULD KEEP PRECIPITATION CHANCES IN THE FORECAST FOR
THE MAJORITY OF HOLIDAY WEEKEND. FOR THE FORECAST HAVE FAVORED THE
MORE PROGRESSIVE SOLUTIONS OF THE GFS AND DGEX WITH MANY OF THE GFS
ENSEMBLES INDICATING A MORE PROGRESSIVE UPPER LEVEL WAVE.
ANDERSON
&&
.AVIATION...
THINK VFR CIGS WILL PERSIST THROUGH THE AFTERNOON. THE MODELS WANT
TO LIFT THE LOW LEVEL MOISTURE ACROSS SOUTHERN MO AND SOUTHEASTERN
KS UP ACROSS TOP AND FOE OVERNIGHT AS SEEN IN THE ISENTROPIC
SURFACES AND 925MB RH PROGS. WITH THE NAM APPEARING TO HAVE A BETTER
GRASP OF CURRENT CONDITIONS...USED IT FOR TIMING MVFR CIGS RETURN
THIS EVENING. RIGHT NOW IT LOOKS LIKE MHK MAY STAY JUST TO THE WEST
OF THE LOW LEVEL MOISTURE.
WOLTERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1055 AM MST SUN NOV 20 2011
.UPDATE...
949 AM MST SUN NOV 20 2011
HIGH TEMPERATURES TRICKY TO NAIL DOWN TODAY DUE TO THE CLOUD
COVER. DESPITE MOST OF THE MODEL GUIDANCE TRENDING TOWARDS
TEMPERATURES IN THE UPPER 30S AND LOW 40S...AM CONCERNED THEY ARE
NOT GRASPING THE CLOUD DECK IN PLACE. THE CLOUDS LOOK TO
DISSIPATE DURING THE AFTERNOON...JUST A MATTER OF IF THEY WILL
DISSIPATE BEFORE PEAK HEATING OR NOT. TO FURTHER COMPLICATE
MATTERS WINDS ACROSS THE AREA RANGE FROM THE SOUTH TO
NORTHEAST...AND WILL BECOME ENTIRELY SOUTHERLY BY MID AFTERNOON
WHICH SHOULD HELP WARM THINGS UP MAINLY IN THE WESTERN AREAS AS
THE CLOUD COVER DISSIPATES. CLOUD COVER SHOULD DISSIPATE FROM WEST
TO EAST ACROSS THE CWA DURING THE AFTERNOON. DID COOL TEMPERATURES
A FEW DEGREES AS THE RUC IS SHOWING THE CLOUDS HANGING THROUGH
MOST OF THE PEAK HEATING.
JTL
&&
.DISCUSSION...
200 AM MST SUN NOV 20 2011
TODAY-TUESDAY NIGHT...SFC HIGH OVER THE NORTHERN AND CENTRAL PLAINS
WILL MOVE AWAY FROM THE AREA MONDAY AS AN OPEN UPPER LEVEL WAVE
MOVES ACROSS THE AREA MONDAY NIGHT. FOR TUESDAY-TUESDAY NIGHT
UPPER RIDGE BUILDS OVER THE AREA.
WILL CONTINUE LOW POPS ACROSS THE SOUTH AND SOUTHEAST MONDAY NIGHT.
TEMPERATURES TODAY IN THE UPPER 30S TO LOW 40S WITH LOW 50S MONDAY
AND MID 50S TUESDAY. OVERNIGHT LOWS GENERALLY IN THE 20S EXCEPT
NEAR 30 TUESDAY NIGHT.
007
FOR THE PERIOD WEDNESDAY THROUGH SATURDAY...SHORTWAVE RIDGING EARLY
IN THE PERIOD WILL TRANSITION TO SOUTHWEST FLOW AHEAD OF THE NEXT
SYSTEM APPROACHING FROM THE DESERT SOUTHWEST. DRY CONDITIONS AND
ABOVE NORMAL TEMPERATURES WILL RESULT FOR WEDNESDAY THROUGH FRIDAY.
AFOREMENTIONED SYSTEM WILL TRACK ACROSS THE SOUTHERN PLAINS ON
FRIDAY AND APPEARS PRECIPITATION WILL ONCE AGAIN MISS THE LOCAL AREA
AS DRY WESTERLY DOWNSLOPING WINDS DOMINATE THE FORECAST PROFILES.
NONETHELESS MORE SEASONABLY COOL TEMPERATURES WILL FOLLOW FOR
SATURDAY. 024
&&
.AVIATION...
1040 AM MST SUN NOV 20 2011
VFR CONDITIONS WILL PREVAIL FOR THE 18Z TAFS. LOW CLOUDS AT KGLD
HAVE MOVED OUT FASTER THAN ANTICIPATED SO KEPT OUT ANY MENTION OF
LOW CLOUDS FOR THE LATEST TAF. THERE COULD BE A SHORT TIME PERIOD
OF SCATTERED MID CLOUDS OVERNIGHT BEFORE THE DECK BECOMES BROKEN
AGAIN...AS MOISTURE AHEAD OF THE NEXT TROUGH CURRENTLY OVER THE WEST
COAST MOVES IN. CURRENTLY KMCK HAS SCATTERED MVFR CEILINGS. SINCE
THE MID CLOUDS ARE NOT AS THICK THERE...AM THINKING THE ADDED
MIXING SHOULD PREVENT A BROKEN MVFR DECK. MOST GUIDANCE HAS THE
DECK REMAINING SCATTERED AT BEST. OVERNIGHT THE VIS MAY BECOME
REDUCED FOR KMCK AND KGLD AS WINDS WILL BE LIGHT AND DEW POINT
DEPRESSIONS WILL BE SMALL. HOWEVER CURRENT POINT SOUNDINGS ARE ONLY
SATURATED AT GROUND LEVEL...SO WILL LEAVE OUT A MENTION OF REDUCED
VIS AT THIS TIME.
JTL
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1121 AM CST SUN NOV 20 2011
.DISCUSSION...
.AVIATION...
FOR THE 18Z TAF ISSUANCE...CLOUDS ARE EXPECTED TO GRADUALLY
DECREASE FROM SOUTHWEST TO NORTHEAST THIS AFTERNOON AS AN UPPER
LEVEL DISTURBANCE EXITS NEW MEXICO AND CROSSES SOUTHWESTERN KANSAS
AND WESTERN OKLAHOMA. THE LOW IFR/MVFR CIGS CURRENTLY PERSISTING
ACROSS SOUTH CENTRAL AND PARTS OF SOUTHWEST KANSAS WILL CONTINUE
FOR THE NEXT SEVERAL HOURS BEFORE GIVING WAY TO VFR CONDITIONS.
SURFACE WINDS WILL BECOME LIGHT BY EARLY TONIGHT AND THEN
GRADUALLY SHIFT TO THE SOUTHEAST BY EARLY MONDAY MORNING AS A
SURFACE RIDGE OF HIGH PRESSURE BUILDS INTO CENTRAL/EASTERN KANSAS. -RB
&&
PREV DISCUSSION... /ISSUED 228 AM CST SUN NOV 20 2011/
SYNOPSIS...
WATER VAPOR LOOP AND RUC ANALYSIS AS OF 20/07Z SHOWED AN EXITING
UPPER TROPOSPHERIC JET STREAK CENTERED FROM SOUTH DAKOTA THROUGH
NORTHERN WISCONSIN. A SUBTROPICAL JET EXTENDED FROM CENTRAL BAJA
CALIFORNIA NORTHEAST INTO WEST TEXAS...WHICH WAS RESPONSIBLE FOR A
LARGE AREA OF CIRRIFORM CLOUD COVER OVER MUCH OF THE CENTRAL PLAINS
SOUTHWEST INTO WEST TEXAS. FARTHER WEST...AN UPPER LOW CONTINUED TO
DIG SOUTH JUST OFF THE COAST OF NORTHERN CALIFORNIA. AT THE
SURFACE...THE STRONG COLD FRONT WHICH PROVIDED KANSAS WITH THE
COLDEST AIRMASS OF THE YOUNG COLD SEASON WAS MOVING INTO NORTHWEST
TEXAS...AND EXTENDED NORTHEAST INTO NORTHWEST ARKANSAS. THE CENTER
OF THE ARCTIC HIGH WAS STILL POSITIONED OVER THE NORTHERN PLAINS
WHERE TEMPERATURES IN THE CORE OF THE ARCTIC AIRMASS IN THE WESTERN
DAKOTAS AND EASTERN MONTANA WERE ANYWHERE FROM 0F TO -10F. A
COMPARISON OF THE 06Z OBS WITH THE 6-HR FORECAST FROM THE NAM12
SHOWS A WIDESPREAD 4 TO 7 DEGREE WARM BIAS IN THE MODEL 2M
TEMPERATURES IN THE ARCTIC AIRMASS FROM CENTRAL NEBRASKA INTO THE
DAKOTAS. AHEAD OF THE FRONT IN TEXAS...ANOMALOUS MOISTURE RETURN WAS
UNDERWAY WITH 70F DEWPOINTS REACHING AS FAR NORTH AS A WACO TO
TYLER, TEXAS LINE. -UMSCHEID
DISCUSSION...
DAYS 1-2 /TODAY THROUGH MONDAY NIGHT/...
TODAY:
INHERITED FORECAST HIGHS (UPPER 30S NORTHEAST HALF TO THE LOWER 40S
SOUTHWEST) FOR TODAY LOOK PRETTY GOOD AND SEE NO REASON TO ADJUST AS
THEY ARE ALREADY A FEW DEGREES COLDER THAN THE GUIDANCE AND GRIDDED
2M TEMPS. WINDS SHOULD BE RATHER LIGHT AS THE SURFACE RIDGE AXIS
MOVES ACROSS KANSAS TODAY. WINDS WILL EVENTUALLY SHIFT TO THE EAST
BY LATE IN THE DAY WITH THE RIDGE AXIS WEAKENING AND MOVING TO THE
EAST. THE NAM12 STILL SHOWS A SIGNAL OF DEVELOPING A NARROW BAND OF
STRATUS AND EVEN PERHAPS SOME LIGHT FREEZING DRIZZLE WITHIN THE BAND
OF DEFORMATION/THERMAL GRADIENT IN THE 850-800MB LAYER OVER THE
SOUTHEASTERN ZONES. WILL KEEP A MENTION OF PATCHY FREEZING
DRIZZLE...BUT CONFINE IT TO THE FAR SOUTHEAST...MAINLY COMANCHE AND
BARBER COUNTIES.
TONIGHT:
THE UPPER LOW OFF THE COAST OF CALIFORNIA WILL HAVE MOVED SOUTHEAST
TO CALIFORNIA/BAJA CALIFORNIA BORDER AREA BY LATE TONIGHT. WILL
START TO SEE A RESPONSE ACROSS WEST AND SOUTHWEST TEXAS WITH
INCREASING WINDS OFF THE SURFACE AND LOW LEVEL MOISTURE (+10 TO +12C
850MB DEWPOINT) MAKING A RUN ON THE TEXAS PANHANDLE BY THE END OF
THIS PERIOD. A WEAK SURFACE LOW WILL DEVELOP ALONG THE STALLED OUT
FRONT OVER SOUTHEASTERN NEW MEXICO AND ADJACENT SOUTHWEST TEXAS WITH
STRONG 850MB FLOW ABOVE THE SHALLOW COLD AIRMASS RESULTING IN
STRATUS DEVELOPMENT INTO THE TEXAS PANHANDLE BY 12Z MONDAY. DESPITE
THE WEAK WINDS AT THE SURFACE...LOWS SHOULD NOT GET MUCH BELOW
22-25F RANGE WITH SOME HIGH CLOUD COVER TIED TO THE SOUTHERN BRANCH
JET LINGERING AROUND WESTERN KANSAS.
MONDAY:
A FAIRLY ROBUST POTENTIAL VORTICITY ANOMALY WILL BE ROUNDING THE
BASE OF THE TROUGH AND EJECT NORTHEASTWARD OUT INTO EASTERN NEW
MEXICO AND WEST TEXAS. THIS IS USUALLY A FAVORABLE TRACK FOR HEAVY
PRECIPITATION ACROSS PORTIONS OF THE DDC FA. WARM FRONTOGENESIS
WILL INCREASE ACROSS THE TEXAS PANHANDLE WITH SHOWERS AND
THUNDERSTORMS BLOSSOMING BY EARLY AFTERNOON. THE RAIN AND
THUNDERSTORM ACTIVITY WILL LIFT NORTHEAST DURING THE AFTERNOON HOURS
AND IMPINGE OF THE SOUTHERN/SOUTHEASTER DDC FA BY THE END OF THIS
PERIOD. TEMPERATURES ARE EXPECTED TO WARM INTO THE UPPER 30S TO
LOWER 40S IN THE SOUTHEASTERN PORTION OF THE FORECAST AREA SO AM
EXPECTING PRECIPITATION TYPE TO BE ALL RAIN. POPS WILL BE 30 TO 40
PERCENT IN THE FAR SOUTHEAST DDC FA WITH 20 POPS OVER THE REST OF
THE SOUTHERN THROUGH EAST-CENTRAL ZONES.
MONDAY NIGHT:
TYPICALLY...THE TRACK OF SUCH A FORMIDABLE AND COMPACT STORM SYSTEM
FROM EASTERN NEW MEXICO TO NORTHWEST OKLAHOMA IS FAVORABLE FOR HEAVY
PRECIPITATION ACROSS AT LEAST A PORTION OF THE DDC FORECAST AREA.
THERE WILL BE TWO PROBLEMS THAT WILL MITIGATE HEAVY PRECIPITATION
POTENTIAL FOR A LARGER AREA OF SOUTHWEST KANSAS. 1) 700-500MB MEAN
FLOW FROM ABOUT 230 DEGREES MEANS THAT HEAVY RAIN AND THUNDERSTORM
ACTIVITY THAT FORMS IN THE WARM/MOIST CONVEYOR OVER THE TX PANHANDLE
WILL THEN MOVE INTO FAR NORTHEASTERN TEXAS PANHANDLE/NORTHWEST
OKLAHOMA...THEN INTO SOUTH-CENTRAL KANSAS...CLIPPING THE DDC
FORECAST AREA. 2) LATE DEVELOPMENT OF THE 700MB LOW. MODELS SHOW
THE 700MB LOW DEVELOPING AND MATURING EARLY TUESDAY MORNING OVER
SOUTH CENTRAL KANSAS...SUCH THAT ONCE A "WRAP AROUND" COLD CONVEYOR
CAN DEVELOP AND BECOME ESTABLISHED...IT WILL DO SO JUST EAST OF THE
DDC FA. FOR THESE REASONS...AREAS ALONG AND NORTHWEST OF A LIBERAL
TO DODGE CITY TO LARNED LINE STAND TO SEE A VERY LOW POTENTIAL FOR
BENEFICIAL PRECIPITATION (LESS THAN A TENTH OF AN INCH). FAR
SOUTHEAST DDC FA (I.E. KIOWA IN BARBER COUNTY) COULD SEE OVER
THREE-QUARTERS OF AN INCH BY EARLY TUESDAY MORNING. -UMSCHEID
DAYS 3-7 /TUESDAY THROUGH SATURDAY NIGHT/...
THE PERIOD WILL BEGIN WITH INCREASING UPPER LEVEL RIDGING AND
ISENTROPIC DOWNGLIDE DEVELOPING. NORTHWEST SURFACE WINDS WILL
PROBABLY BE ON THE BREEZY SIDE TUESDAY AS SURFACE PRESSURE INCREASES
ACROSS WESTERN KANSAS AS A LARGE SURFACE ANTICYCLONE SHIFTS EASTWARD
FROM SOUTHEAST KANSAS THROUGH THE MID MISSISSIPPI VALLEY. THESE WINDS
WILL DIMINISH TO LIGHT THROUGH TUESDAY NIGHT AND EARLY WEDNESDAY,
BACKING TO THE SOUTHWEST AGAIN AND BECOMING LIGHT SOUTHWEST THROUGH
THE DAY ON WEDNESDAY. THIS TRANSITION SHOULD SUPPORT WARMING
TEMPERATURES FROM THE 50S ON TUESDAY BACK UP TO AROUND 60 OR MORE ON
WEDNESDAY WITH SOUTHERLY FLOW AND WARM AIR ADVECTION/DOWNSLOPE.
THE UPPER PATTERN WILL REMAIN IN A PROGRESSIVE TROUGH - RIDGE -
TROUGH PATTERN THROUGH THE WEEK. FROM WEDNESDAY NIGHT INTO EARLY
FRIDAY, THE MODELS SWING ANOTHER UPPER JET SEGMENT FROM THE SOUTHERN
ROCKIES INTO THE CENTRAL PLAINS. AS A RESULT, ANOTHER DECENT SURFACE
TROUGH WILL DEVELOP OVER THE CENTRAL HIGH PLAINS ON THURSDAY WHICH
WILL PRODUCE BREEZY TO WINDY SOUTHWEST WINDS AGAIN, BETTER MIXING
AND EVEN WARMER TEMPERATURES INTO THE 60S. AS THE UPPER PATTERN
CONTINUES TO EVOLVE INTO A SHARPER TROUGH OVER THE CENTRAL PLAINS,
ANOTHER STRONG COLD FRONT WILL SWEEP INTO THE HIGH PLAINS FROM
MONTANA AND WYOMING, BRINGING STRONG NORTHWEST WINDS AND COLD
ADVECTION FRIDAY OR FRIDAY NIGHT FOLLOWED BY A COOLING TREND INTO
SUNDAY. -RUSSELL
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 39 23 47 33 / 0 0 20 30
GCK 40 22 47 32 / 0 0 10 20
EHA 46 29 50 35 / 0 0 10 20
LBL 44 26 50 34 / 0 0 10 30
HYS 39 20 47 32 / 0 0 10 20
P28 40 26 48 37 / 10 0 40 80
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1002 AM MST SUN NOV 20 2011
.UPDATE...
949 AM MST SUN NOV 20 2011
HIGH TEMPERATURES TRICKY TO NAIL DOWN TODAY DUE TO THE CLOUD
COVER. DESPITE MOST OF THE MODEL GUIDANCE TRENDING TOWARDS
TEMPERATURES IN THE UPPER 30S AND LOW 40S...AM CONCERNED THEY ARE
NOT GRASPING THE CLOUD DECK IN PLACE. THE CLOUDS LOOK TO
DISSIPATE DURING THE AFTERNOON...JUST A MATTER OF IF THEY WILL
DISSIPATE BEFORE PEAK HEATING OR NOT. TO FURTHER COMPLICATE
MATTERS WINDS ACROSS THE AREA RANGE FROM THE SOUTH TO
NORTHEAST...AND WILL BECOME ENTIRELY SOUTHERLY BY MID AFTERNOON
WHICH SHOULD HELP WARM THINGS UP MAINLY IN THE WESTERN AREAS AS
THE CLOUD COVER DISSIPATES. CLOUD COVER SHOULD DISSIPATE FROM WEST
TO EAST ACROSS THE CWA DURING THE AFTERNOON. DID COOL TEMPERATURES
A FEW DEGREES AS THE RUC IS SHOWING THE CLOUDS HANGING THROUGH
MOST OF THE PEAK HEATING.
JTL
&&
.DISCUSSION...
200 AM MST SUN NOV 20 2011
TODAY-TUESDAY NIGHT...SFC HIGH OVER THE NORTHERN AND CENTRAL PLAINS
WILL MOVE AWAY FROM THE AREA MONDAY AS AN OPEN UPPER LEVEL WAVE
MOVES ACROSS THE AREA MONDAY NIGHT. FOR TUESDAY-TUESDAY NIGHT
UPPER RIDGE BUILDS OVER THE AREA.
WILL CONTINUE LOW POPS ACROSS THE SOUTH AND SOUTHEAST MONDAY NIGHT.
TEMPERATURES TODAY IN THE UPPER 30S TO LOW 40S WITH LOW 50S MONDAY
AND MID 50S TUESDAY. OVERNIGHT LOWS GENERALLY IN THE 20S EXCEPT
NEAR 30 TUESDAY NIGHT.
007
FOR THE PERIOD WEDNESDAY THROUGH SATURDAY...SHORTWAVE RIDGING EARLY
IN THE PERIOD WILL TRANSITION TO SOUTHWEST FLOW AHEAD OF THE NEXT
SYSTEM APPROACHING FROM THE DESERT SOUTHWEST. DRY CONDITIONS AND
ABOVE NORMAL TEMPERATURES WILL RESULT FOR WEDNESDAY THROUGH FRIDAY.
AFOREMENTIONED SYSTEM WILL TRACK ACROSS THE SOUTHERN PLAINS ON
FRIDAY AND APPEARS PRECIPITATION WILL ONCE AGAIN MISS THE LOCAL AREA
AS DRY WESTERLY DOWNSLOPING WINDS DOMINATE THE FORECAST PROFILES.
NONETHELESS MORE SEASONABLY COOL TEMPERATURES WILL FOLLOW FOR
SATURDAY. 024
&&
.AVIATION...
426 AM MST SUN NOV 20 2011
FOR THE 12Z TAFS...AREAS OF FOG LINGER JUST TO THE WEST OF KGLD BUT
SO FAR HAVE NOT SHOWN ANY SIGNS OF MOVING INTO THE TERMINAL AREA.
HIGH CLOUDS HAVE PREVENTED RADIATIONAL COOLING AND BELIEVE WILL
ESCAPE WITH VFR CONDITIONS THIS MORNING AT BOTH KGLD AND KMCK.
SURFACE WINDS WILL BE LIGHT...MAINLY FROM THE SOUTH TO
SOUTHEAST...WITH HIGH PRESSURE NOSING IN FROM THE NORTHERN PLAINS.
024
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
344 PM CST SUN NOV 20 2011
.UPDATE...
SEVERE THUNDERSTORM WATCH #893 UNTIL 05Z/11PM THIS EVENING FOR
AREAS FROM GRANBURY AND MARLIN...NORTHEAST TO BONHAM...PARIS AND
PALESTINE. UPDATES FORTH COMING. 75
&&
.PREV DISCUSSION... /ISSUED 157 PM CST SUN NOV 20 2011/
...SEVERE THUNDERSTORM POTENTIAL CONTINUES ACROSS PORTIONS OF NORTH
TEXAS LATER THIS AFTERNOON AND AGAIN ON MONDAY AFTERNOON AND
EVENING...
OVERALL...THIS AFTERNOONS FORECAST PACKAGE CONTINUES THE TRENDS
MENTIONED IN PREVIOUS FORECASTS OVER THE PAST SEVERAL DAYS. THE
COLD FRONT IS RUNNING SLIGHTLY AHEAD OF PREVIOUS TIMING...BUT
FAIRLY CLOSE TO THE NAM AND RUC MODEL SOLUTIONS. AT 145 PM IT
EXTENDS FROM PARIS TO CLEBURNE TO SOUTH OF COMANCHE.
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATER THIS
AFTERNOON THROUGH MID/LATE EVENING AS FORCING FOR ASCENT ARRIVES
FROM THE WEST AND HELPS WEAKEN THE STRONG CAP AROUND 860MB. VERY
MOIST AND UNSTABLE AIR AHEAD OF THE COLD FRONT WILL PRODUCE CAPES
500-1200 J/KG THIS EVENING AND 700-1400 J/KG ON MONDAY. BULK SHEAR
0-6KM WILL BE IN THE RANGE OF 40-60 KTS BOTH DAYS ALONG WITH
HELICITY VALUES GREAT THAN 200 M2/S2. AS PREVIOUSLY STATED...LARGE
HAIL WILL BE THE PRIMARY SEVERE THUNDERSTORM THREAT FOLLOWED BY
DAMAGING WINDS AND BRIEF ISOLATED TORNADOES. AREAS TO WATCH FOR
QUICK TORNADOGENESIS ARE...WHERE SURFACE WINDS ARE BACKED AND
THOSE CELLS THAT MOVE NEAR AND ALONG THE COLD FRONT. HAVE ADDED
SEVERE WORDING TO THE ZONE PACKAGE IN THIS RELEASE.
THE SYSTEM SHOULD MOVE OUT OF NORTH TEXAS LATE TUESDAY AFTERNOON
WITH FAIR WEATHER FOR WEDNESDAY AND THANKSGIVING DAY. OUR NEXT
SYSTEM WILL ARRIVE FRIDAY WITH ANOTHER ROUND OF THUNDERSTORMS AND
BENEFICIAL RAINFALL FOR NORTH TEXAS. THIS SYSTEM WILL MOVE RIGHT
ON THROUGH THE REGION AND SHOULD BE OUT OF NORTH TEXAS LATE FRIDAY
NIGHT. AFTERWARD...IT WILL BE DRY WITH SEASONAL TEMPERATURES OVER
THE WEEKEND. 75
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 60 73 60 69 45 / 50 80 90 40 10
WACO, TX 68 79 63 75 44 / 40 50 80 50 10
PARIS, TX 61 72 62 68 44 / 60 80 90 60 10
DENTON, TX 54 69 55 66 41 / 50 80 90 20 5
MCKINNEY, TX 59 71 59 67 43 / 50 80 90 50 10
DALLAS, TX 61 75 61 70 47 / 50 80 90 50 10
TERRELL, TX 64 76 65 70 45 / 50 60 90 50 10
CORSICANA, TX 67 79 66 75 47 / 50 40 80 70 10
TEMPLE, TX 68 79 65 77 46 / 30 30 70 60 10
MINERAL WELLS, TX 55 72 53 68 40 / 40 80 90 20 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25/75
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
247 PM CST SUN NOV 20 2011
.SHORT TERM...
MAIN FOCUS FOR THE SHORT TERM PERIOD IS THE IMPENDING WEST COAST
SYSTEM THAT WILL BRING CHANCES OF RAIN COMMENCING TOMORROW...AND
TAMPERING OFF TUESDAY MORNING.
THE PACIFIC UA LOW SYSTEM OF INTEREST WAS LOCATED OFF THE COAST OF
CENTRAL CALIFORNIA PER 20Z WATER VAPOR IMAGERY...AND PROGGED TO OPEN
UP AND EJECT QUICKLY ESE TO ACROSS THE DESERT SOUTHWEST MONDAY
MORNING...ACROSS THE SOUTH PLAINS MONDAY NIGHT AND EAST OF THE
REGION TUESDAY MORNING. THIS RELATIVELY QUICK TRAJECTORY IS BEING
HANDLED WELL BY THE NAM...GFS AND ECMWF SOLUTIONS...WITH PERHAPS THE
NAM BEING A TOUCH FASTER THAN THE LATTER MODELS. 20Z SFC ANALYSIS
DISPLAYED A COLD FRONT THAT SURGED SOUTH ACROSS THE CWA EARLIER THIS
MORNING...AND WAS SPATIALLY DISTRIBUTED FROM A NEAR PINE SPRINGS TO
FORT STOCKTON TO BRADY LINE. THUS LEAVING TEMPS IN THE 40S AND 50S
AND DEWPOINTS IN THE 20S AND 30S IN ITS WAKE. THIS PLACEMENT OF THE
SAID FRONT IS FARTHER SOUTH THAN WHAT MODELS PREDICTED 24 HOURS AGO.
THE GFS AND ECMWF ARE ONLY SLIGHTLY SIMILAR TO THE NAM IN REGARD TO
THE FRONT NOT BEING QUITE AS FAR SOUTH...HENCE THE CURRENT PLACEMENT
OF THE FRONT IS NOT HANDLED WELL BY EITHER AFOREMENTIONED SOLUTION
PER SE. HENCE...THE NAM AND RUC MODELS DISPLAY THE FRONT TRANSLATING
A BIT FARTHER SOUTH TONIGHT /THE RUC IS MOST AGGRESSIVE WITH THIS
POSSIBILITY/ BUT THE NAM AND TO A LESSER EXTENT THE GFS HAS A WARM
TONGUE OOZING IN ACROSS THE FAR SOUTHWESTERN ZONES.
IF FOLLOWING THE NAM SOLUTION WITH A SLIGHT RELIANCE ON THE GFS
SOLUTION...THE SUB-TROPICAL FETCH OF MOISTURE WILL CONTINUE TO SPILL
ACROSS THE SOUTH PLAINS AND THUS HIGH LEVEL CLOUDINESS WILL PREVAIL
THE REST OF TODAY AND TONIGHT. A 1025 SFC RIDGE WILL SETTLE IN NE OF
THE REGION AND INDUCE GENERALLY LIGHT EAST TO SOUTHEAST/UPSLOPE SFC
WINDS TONIGHT. AS A RESULT...LOW LEVEL MOISTURE WILL INCREASE AS
MODEL SOUNDINGS DISPLAYED PROGGED PWATS NEARING 1.00 INCH
PARTICULARLY ACROSS THE CENTRAL TO EASTERN SOUTH PLAINS. THE
SYNOPTIC LIFT IS NOT STRONG AT THIS POINT...BUT CURRENT THINKING IS
THAT LOW LEVEL STRATUS WILL DEVELOP FROM SOUTH TO NORTH WITH PERHAPS
ISENTROPIC UPGLIDE BEING ENOUGH TO INDUCE LIGHT DRIZZLE ACROSS THE
AFOREMENTIONED AREAS EARLY TOMORROW MORNING. AOA 12Z...INDICATIONS
OF LOCALIZED PATCHY FOG MAY DEVELOP AND LAST THROUGH MID-MORNING
ACROSS PORTIONS OF THE CWA...AS THE SYSTEM NEARS THE WESTERN FRINGES
OF THE SOUTH PLAINS. BY EARLY AFTERNOON...SYNOPTIC LIFT HAS
INCREASED AND MUCAPE VALUES IS ANTICIPATED TO NEAR 1000 J/KG
ESPECIALLY ACROSS EASTERN ZONES. THUS...ADEQUATE MUCAPE AND 0-6 KM
SHEAR VALUES NEARING 70 KTS MAY PROMOTE ISOLATED STRONG TO POSSIBLY
SEVERE THUNDERSTORMS WHERE HAIL IS THE PRIMARY THREAT...ACROSS
EASTERN ZONES DURING THE EARLY TO MID AFTERNOON. THE 15Z-00Z
TIME-FRAME APPEARS TO BE WHEN THE SYNOPTIC LIFT IS AT ITS
BEST...WITH A NOTICEABLE DECLINATION THEREAFTER. IT IS ALSO DURING
THE AFOREMENTIONED TIME-FRAME WHERE THE FRONT IS ANTICIPATED TO
RETREAT NORTH TO NEAR THE SOUTHEASTERN ZONES BEFORE THE PACIFIC
FRONT SWEEPS IN FROM WEST TO EAST...DRY SLOTTING THE REGION LATE
MONDAY NIGHT/EARLY TUESDAY MORNING. THUS THE OVERALL TREND APPEARS
TO BE LIGHT DRIZZLE EARLY MONDAY MORNING FOLLOWED BY INCREASING RAIN
CHANCES WITH HIGHEST POPS DISPLAYED 18Z-00Z ACROSS THE
EAST...COINCIDING WITH BEST SYNOPTIC LIFT AS THE SYSTEM COMMENCES TO
MOVE ACROSS THE REGION. THEREAFTER...PRECIP WILL DECLINE FROM WEST
TO EAST BY TUESDAY 12Z.
TEMPS OVER NIGHT TONIGHT WILL BE RELATIVELY MILD WITH MID TO UPPER
30S NORTH TO LOWER TO MID 40S SOUTH EXPECTED....AS HIGH-LEVEL
CLOUDINESS ENSUE AND EVENTUALLY LOW LEVEL STRATUS DEVELOPS. TEMPS
TOMORROW COULD BE A BIT TRICKY DEPENDING ON IF THE PACIFIC FRONT
MOVING IN FROM THE WEST DRY SLOTS THE AREA QUICKER THAN ANTICIPATED.
HOWEVER...WILL LEAN TOWARDS A RANGE OF UPPER 40S TO LOWER 50S NE TO
LOWER 60S SW AS HINTED AT BY MOS GUIDANCE.
&&
.LONG TERM...
TUES 12Z...THE COLD FRONT WILL BE NEARLY IF NOT ALL THE WAY THRU THE
FA...ALLOWING THE AREA TO DRY OUT. BY WED 06Z...SKIES WILL BE CLEAR
WITH LITTLE RESIDUAL MOISTURE LEFT IN THE LOW LVLS.
THEREFORE...EXPECT TEMPS TO FALL SOME OVERNIGHT ACROSS THE AREA.
THOUGH AS SRLY SFC FLOW RETURNS...THE SHORTWAVE RIDGING ALSO MOVES
INTO THE AREA. THIS WILL ALLOW FOR A BRIEF WARMING TREND AHEAD THE
NEXT UL TROF EXPECTED TO MOVE INTO THE REGION ON TURKEY DAY. THIS
TROF IS PROGGED TO BE FAIRLY LOW AMPLITUDE AS IT MOVE ACROSS THE FA
PREVENTING MUCH IN THE WAY OF MOISTURE RETURN. THEREFORE...WILL
CONTINUE THE DRY EXTENDED FORECAST. ALSO...WINDS ASSOCIATED WITH
THIS SYSTEM LOOK FAIRLY ROBUST /AOA 40KTS AT 850/ AND GIVEN DRY
CONDITIONS THERE CONTINUE TO BE SOME FIRE WEATHER CONCERNS. THAT
BEING SAID GIVEN THE TIMING CURRENTLY PROGGED THESE WINDS WILL RAMP
UP IN THE COLD AIR AND LATE IN THE DAY AS THE TROF PUSHES THRU THE
REGION. ALSO...AS THE TROF EXITS THE REGION A SECOND SURGE OF ENERGY
TRAVERSES THE TROF PUSHING A STRONG COLD FRONT THRU THE AREA
OVERNIGHT FRI.
MEADOWS
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 36 55 34 60 31 / 10 30 20 0 0
TULIA 35 51 36 60 32 / 20 50 20 0 0
PLAINVIEW 36 52 37 61 33 / 20 50 20 0 0
LEVELLAND 41 60 40 63 34 / 20 30 10 0 0
LUBBOCK 41 54 40 63 34 / 20 40 20 0 0
DENVER CITY 44 63 42 64 36 / 20 20 10 0 0
BROWNFIELD 43 62 41 63 36 / 20 30 10 0 0
CHILDRESS 36 49 39 65 36 / 20 70 40 0 0
SPUR 42 50 41 64 37 / 20 60 20 0 0
ASPERMONT 45 53 44 63 37 / 20 70 40 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
29/40
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
157 PM CST SUN NOV 20 2011
.DISCUSSION...
...SEVERE THUNDERSTORM POTENTIAL CONTINUES ACROSS PORTIONS OF NORTH
TEXAS LATER THIS AFTERNOON AND AGAIN ON MONDAY AFTERNOON AND
EVENING...
OVERALL...THIS AFTERNOONS FORECAST PACKAGE CONTINUES THE TRENDS
MENTIONED IN PREVIOUS FORECASTS OVER THE PAST SEVERAL DAYS. THE
COLD FRONT IS RUNNING SLIGHTLY AHEAD OF PREVIOUS TIMING...BUT
FAIRLY CLOSE TO THE NAM AND RUC MODEL SOLUTIONS. AT 145 PM IT
EXTENDS FROM PARIS TO CLEBURNE TO SOUTH OF COMANCHE.
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATER THIS
AFTERNOON THROUGH MID/LATE EVENING AS FORCING FOR ASCENT ARRIVES
FROM THE WEST AND HELPS WEAKEN THE STRONG CAP AROUND 860MB. VERY
MOIST AND UNSTABLE AIR AHEAD OF THE COLD FRONT WILL PRODUCE CAPES
500-1200 J/KG THIS EVENING AND 700-1400 J/KG ON MONDAY. BULK SHEAR
0-6KM WILL BE IN THE RANGE OF 40-60 KTS BOTH DAYS ALONG WITH
HELICITY VALUES GREAT THAN 200 M2/S2. AS PREVIOUSLY STATED...LARGE
HAIL WILL BE THE PRIMARY SEVERE THUNDERSTORM THREAT FOLLOWED BY
DAMAGING WINDS AND BRIEF ISOLATED TORNADOES. AREAS TO WATCH FOR
QUICK TORNADOGENESIS ARE...WHERE SURFACE WINDS ARE BACKED AND
THOSE CELLS THAT MOVE NEAR AND ALONG THE COLD FRONT. HAVE ADDED
SEVERE WORDING TO THE ZONE PACKAGE IN THIS RELEASE.
THE SYSTEM SHOULD MOVE OUT OF NORTH TEXAS LATE TUESDAY AFTERNOON
WITH FAIR WEATHER FOR WEDNESDAY AND THANKSGIVING DAY. OUR NEXT
SYSTEM WILL ARRIVE FRIDAY WITH ANOTHER ROUND OF THUNDERSTORMS AND
BENEFICIAL RAINFALL FOR NORTH TEXAS. THIS SYSTEM WILL MOVE RIGHT
ON THROUGH THE REGION AND SHOULD BE OUT OF NORTH TEXAS LATE FRIDAY
NIGHT. AFTERWARD...IT WILL BE DRY WITH SEASONAL TEMPERATURES OVER
THE WEEKEND. 75
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 60 73 60 69 45 / 50 80 90 40 10
WACO, TX 68 79 63 75 44 / 40 50 80 50 10
PARIS, TX 61 72 62 68 44 / 60 80 90 60 10
DENTON, TX 54 69 55 66 41 / 50 80 90 20 5
MCKINNEY, TX 59 71 59 67 43 / 50 80 90 50 10
DALLAS, TX 61 75 61 70 47 / 50 80 90 50 10
TERRELL, TX 64 76 65 70 45 / 50 60 90 50 10
CORSICANA, TX 67 79 66 75 47 / 50 40 80 70 10
TEMPLE, TX 68 79 65 77 46 / 30 30 70 60 10
MINERAL WELLS, TX 55 72 53 68 40 / 40 80 90 20 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25/75
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1205 PM CST SUN NOV 20 2011
.AVIATION...
/18Z TAFS/
CONCERNS...CIGS AND TIMING OF PRECIP.
AT ISSUANCE TIME...FRONT WAS APPROACHING LOVE FIELD...PAST
TERMINAL AT VALID TIME OF 18Z TAFDAL. AFW NOW REPORTING IFR
CIGS...BUT EXPECT POSTFRONTAL CONDITIONS TO BE DOMINATED BY MVFR
CONDITIONS. CONVECTIVE INITIATION THIS AFTERNOON NEAR THE SURFACE
BOUNDARY WILL LIKELY REMAIN SOUTHEAST OF METRO TAF SITES. THUNDER
MAY SPREAD NORTH OF THE BOUNDARY THIS EVENING AS LLJ INITIATES.
HAVE REDUCED MENTION TO CB UNTIL TIME FRAME CAN BE BETTER
REPRESENTED.
WACO WILL EXPERIENCE VEERING WINDS THIS AFTERNOON...BUT WILL
REMAIN SOUTH OF THE BOUNDARY. SOME SHOWERS UPSTREAM OVER HILL
COUNTRY. WILL MONITOR POTENTIAL FOR CONVECTIVE DEVELOPMENT THIS
AFTERNOON...BUT CONFIDENCE IS TOO LOW TO INCLUDE SPECIFIC MENTION
WITH 18Z ISSUANCE.
MONDAY...IFR CONDITIONS WITH SHRA (OCCASIONAL TSRA).
25
&&
.UPDATE...
COLD FRONT HAS MOVED INTO THE WESTERN METROPLEX AS OF 10 AM PER
SURFACE OBS AND RADAR SIGNATURE...WHICH IS MORE IN LINE WITH THE
NAM AND RUC MODELS. HAVE ADJUSTED GRIDS TO REFLECT ITS CURRENT
POSITION AND A SLOW PROGRESSION TO THE SOUTHEAST THROUGH MID
AFTERNOON. MAY REACH A CANTON TO LAMPASAS LINE BY 6 PM THIS
EVENING. MAX TEMPS...HOURLY TEMP...DEWPOINT AND WIND GRIDS WERE
ALSO ADJUSTED THROUGH MID AFTERNOON.
BRIEF LOOK AT THE LATEST GFS AND THE EARLIER NAM/RUC SERIES SHOW A
DIFFERENCE IN THE FRONTAL POSITION OVER THE NEXT 24 HOURS...WHICH
RESULTS IN A LOCATION DIFFERENCE IN WHERE CONVECTION/RAIN WILL
OCCUR THIS AFTERNOON AND OVERNIGHT. SINCE THE NAM/RUC HAVE THE
BEST INITIALIZATION OF THE FRONT...WILL CONTINUE TO FAVOR THEIR
PRECIPITATION PROCESS ALONG AND AHEAD OF THE THE FRONT THIS
AFTERNOON AND TONIGHT. THE PREVIOUS FORECAST HAD THIS APPROACH
BUILT INTO IT...THUS DO NOT FEEL A NEED TO ADJUST TIMING OR
LOCATIONS OF PRECIPITATION IN THIS UPDATE. EVEN THE FORECAST FOR
MONDAY THROUGH MONDAY NIGHT SEEMS ON TRACK WITH THIS MORNING
MODEL RUNS. ONE THING THAT COULD CHANGE IN THE AFTERNOON PACKAGE
WOULD BE THE TIMING FOR ENDING THE RAIN WEST TO EAST ON TUESDAY.
75
&&
.PREV DISCUSSION... /ISSUED 508 AM CST SUN NOV 20 2011/
EARLY MORNING WATER VAPOR IMAGERY DEPICTED SHORTWAVE TROUGHS OVER
THE NORTHERN CONUS ROCKIES...OVER THE BAJA PENINSULA AND JUST OFF
THE NORTHERN CA COAST. A PLUME OF TROPICAL PACIFIC MOISTURE WAS
STREAMING OVER THE SOUTHERN ROCKIES AND OVER THE SOUTHERN PLAINS.
A COLD FRONT CHARACTERIZED BY A STRONG LOW LEVEL BAROCLINIC ZONE
REMAINED JUST TO THE NORTHWEST OF THE CWA AS OF 09Z...AND WAS
LOCATED APPROXIMATELY ALONG AN ARDMORE TO THROCKMORTON LINE.
ALTHOUGH THE FRONT HAS SLOWED DOWN SIGNIFICANTLY OVERNIGHT...IT
CONTINUES TO PUSH SOUTHEAST EARLY THIS MORNING AND WILL LIKELY
ENTER THE FAR NORTHWESTERN COUNTIES OF OUR FORECAST AREA BY 12Z.
TEMPERATURES FALL RAPIDLY BEHIND/NORTH OF THE FRONT WITH A 09Z
TEMPERATURE OF 61 AT BOWIE AND ONLY 46 AT WICHITA FALLS.
TODAY AND TONIGHT...THE BAJA SHORTWAVE TROUGH IS EXPECTED TO MOVE
QUICKLY NORTHEAST DURING THE DAY TODAY AND IS EXPECTED TO BE
LOCATED OVER THE CENTRAL PLAINS BY EARLY THIS EVENING. THIS FAST
MOVING BUT SOMEWHAT WEAK TROUGH WILL SPREAD SOME LARGE SCALE
FORCING FOR ASCENT OVER THE SOUTHERN PLAINS TODAY AHEAD OF THE
COLD FRONT. THE TROUGH ITSELF IS EXPECTED TO REMAIN WELL TO THE
NORTH OF THE CWA...SO IT WILL LIKELY NOT PLAY A SIGNIFICANT ROLE IN
PRECIPITATION CHANCES DURING THE PERIOD. TODAY/S PRIMARY FORECAST
CHALLENGE IS WITH REGARDS TO CONVECTIVE INITIATION ALONG THE COLD
FRONT...WHICH IS EXPECTED TO STALL OUT SOMEWHERE OVER NORTH TX BY
EARLY THIS AFTERNOON.
ONE CHALLENGE REGARDING CONVECTIVE INITIATION THIS AFTERNOON IS
FORECASTING WHERE THE FRONT WILL STALL OUT. 00 AND 06Z GUIDANCE
HAS FAILED TO COME UP WITH A CONSENSUS POSITION OF THE STALLED OUT
FRONT. THE COARSER RESOLUTION GUIDANCE INDICATES THAT THE FRONT
WILL STALL OUT NEAR THE DFW METROPLEX WHILE THE HIGHER RESOLUTION
GUIDANCE INDICATES THAT THE FRONT WILL MAKE IT AS FAR SOUTHEAST AS
A SULPHUR SPRINGS TO HILLSBORO TO GOLDTHWAITE LINE. NEITHER
SOLUTION INITIALIZED THE CURRENT POSITION OF THE FRONT
PERFECTLY...SO OPTED TO GO WITH A BLEND AND JUST PUSHED THE FRONT
FURTHER SOUTHEAST THAN PREVIOUS FORECAST HAD INDICATED FOR THIS
AFTERNOON. THINK THAT BEST PRECIPITATION CHANCES WILL REMAIN ALONG
THE FRONTAL BOUNDARY FOR THIS AFTERNOON...SO ADJUSTED POPS
ACCORDINGLY TAKING THE HIGHER AXIS OF 40/50 POPS A BIT FURTHER
SOUTHEAST FOR THIS AFTERNOON AND THIS EVENING.
THE OTHER CHALLENGE REGARDING CONVECTIVE INITIATION TODAY IS
IDENTIFYING A STRONG FORCING MECHANISM. THE STALLED OUT COLD FRONT
IS THE OBVIOUS FEATURE IN PLAY BUT THE LIMITING FACTOR REGARDING
FORCING ALONG THE FRONT IS THE FACT THAT IT IS EXPECTED TO BE
STATIONARY BY THIS AFTERNOON. WITHOUT MOVEMENT THERE WILL NO
FORCED CONVECTION OUT AHEAD OF THE FRONT ASSOCIATED WITH DYNAMIC
PRESSURE PERTURBATIONS. THE PRIMARY FORCING MECHANISM ASSOCIATED
WITH THE FRONT THEN APPEARS TO BE FRONTOGENESIS WHICH IS TYPICALLY
MAXIMIZED BEHIND THE LEADING EDGE OF THE SURFACE FRONT. MOST SREF
ENSEMBLE MEMBERS DEPICT A LOW LEVEL CAPPING INVERSION IN PLACE
OVER NORTH TX THIS AFTERNOON. WHILE WE WILL HAVE SOME MODEST LOW
LEVEL WARM AIR ADVECTION SOUTH OF THE FRONTAL BOUNDARY TODAY THE
PRESENCE OF THIS CAP /ASSUMING IT EXISTS/ SHOULD LIMIT THE
INITIATION OF TSTM ACTIVITY TO THE IMMEDIATE VICINITY OF THE FRONT.
WITH THIS IN MIND NARROWED THE BAND 30 TO 50 POPS TODAY TO THOSE
LOCATIONS WHERE THE FRONT MAY REASONABLY STALL OUT. DID NOT GO ANY
HIGHER THAN 50 POPS IN THE CWA THRU 00Z AS ALL CONVECTION ALLOWING
GUIDANCE KEEPS TSTM ACTIVITY OUT OF NORTH TX THIS AFTERNOON WHILE
ALL OTHER GUIDANCE INDICATES DEVELOPING CONVECTION ALONG THE FRONT
BETWEEN 21 TO 00Z. THE LACK OF LARGE SCALE FORCING FOR ASCENT
TENDS TO FAVOR A SLOW LIFTING OR STRONGER CAP SO WILL REMAIN
CAUTIOUS WITH REGARDS TO POPS UNTIL 12Z UPPER AIR DATA COMES IN AS
WELL AS AIRCRAFT DATA SOUNDING DATA LATER THIS MORNING.
IF TSTMS ARE ABLE TO INITIATE ALONG THE FRONT THIS
AFTERNOON...THERE IS A CHANCE THAT THEY WILL BECOME SEVERE. SREF
MEAN SURFACE BASED CAPE VALUES ARE AROUND 1000 J/KG SOUTH OF THE
FRONT TODAY AND ALL OPERATIONAL GUIDANCE ADVERTISES AT LEAST THIS
MUCH POTENTIAL INSTABILITY. DEEP LAYER SHEAR IS EXPECTED TO BE
AROUND 40 TO 50 KTS THIS AFTERNOON WHICH WOULD SUPPORT AN
ORGANIZED CONVECTIVE MODE. DEW POINT VALUES THIS MORNING ARE
EXCEPTIONALLY HIGH FOR NOVEMBER...WITH DEW POINTS IN THE LOWER 70S
OBSERVED FROM HEARNE SOUTHEAST TO THE GULF COAST. WE WOULD NEED
JUST A FEW BREAKS IN THE LOW CLOUD COVER THIS AFTERNOON TO SEE
CAPE VALUES JUMP UP ABOVE 1000 J/KG. BECAUSE CLOUDS ARE EXPECTED
TO HOLD IN FOR MUCH OF THE DAY...OVERALL TORNADO POTENTIAL IS LOW
DUE TO POOR LOW LEVEL LAPSE RATES LIMITING VORTEX STRETCHING
POTENTIAL. LARGE HAIL LOOKS TO BE THE PRIMARY THREAT IN THIS
ENVIRONMENT WITH THE DAMAGING WIND AND TORNADO POTENTIAL PERKING
UP IN ANY AREAS THAT SEE A FEW HOURS OF SUNSHINE TODAY. WOULD
EXPECT A LARGELY LINEAR/QLCS STORM MODE AS DEEP LAYER SHEAR
VECTORS ARE EXPECTED TO BE NEARLY PARALLEL TO THE STATIONARY
FRONT.
TSTM ACTIVITY IS EXPECTED TO INCREASE IN COVERAGE TONIGHT AS THE
SHALLOW COLD FRONT INTERACTS WITH THE DEVELOPING LOW LEVEL JET.
THE LOW LEVEL JET IS EXPECTED TO RAMP UP IN ADVANCE OF THE NEXT
APPROACHING SHORTWAVE TROUGH WHICH IS MUCH STRONGER THAN THE BAJA
TROUGH. THE COLD FRONT WILL EFFECTIVELY STEEPEN LOW LEVEL
ISENTROPIC SURFACES ALLOWING FOR SIGNIFICANT ISENTROPIC LIFT
AFTER MIDNIGHT AS THE LLJ RIDES OVER THIS BOUNDARY. THIS FORCING
IS MUCH MORE BROAD THAN THE NARROW FRONTOGENETIC FORCING ALONG THE
FRONT...SO WENT AHEAD AND SPREAD POPS OUT OVER MUCH OF NORTH TX
LATE OVERNIGHT AND THRU MONDAY MORNING AS THE FRONT GRADUALLY
LIFTS BACK NORTH MONDAY MORNING. STORMS SUNDAY NIGHT WILL LIKELY
BE ELEVATED IN NATURE AND SHOULD ONLY POSE A LOWER END SEVERE HAIL
THREAT.
MONDAY AFTERNOON THRU TUESDAY...THE TROUGH THAT CURRENTLY RESIDES
OFF THE NORTHERN CA COAST WILL MOVE THRU THE SOUTHERN PLAINS LATE
MONDAY AFTERNOON THRU THE EVENING HRS. THIS SHOULD RESULT IN
WIDESPREAD TSTM ACTIVITY THRU MUCH OF THE REGION DURING THIS
PERIOD. WITH STRONG FORCING FOR ASCENT ASSOCIATED WITH THE
POWERFUL UPPER TROUGH WENT AHEAD WITH SREF SUGGESTED POPS DUE TO
THE STRONG SYNOPTIC SIGNALS IN PLACE.
FOR OUR CWA...MOST CONFIDENT IN TSTM ACTIVITY NEAR ANY FRONTAL
BOUNDARY DURING THE PERIOD SO HAVE PLACED 80 POPS OR HIGHER NEAR
THE EXPECTED POSITION OF SYNOPTIC FRONTS. ANY STORMS THAT DEVELOP
MONDAY AFTERNOON OR EVENING WILL HAVE THE POTENTIAL TO BECOME
SEVERE WITH DEEP MOISTURE AND EVEN STRONGER SHEAR IN PLACE THAN
WHAT IS EXPECTED FOR SUNDAY AFTERNOON. PRIMARY SEVERE
THUNDERSTORM HAZARDS WILL BE DEPENDENT UPON WHERE FRONTAL
BOUNDARIES LIE AND WHERE STORMS DEVELOP. WHILE THE CONFIDENCE OF
TSTMS OCCURRING IS HIGH...THE CONFIDENCE REGARDING THESE DETAILS
IS FAIRLY LOW AT THIS TIME.
STORMS THAT DEVELOP ALONG THE RETREATING FRONTAL BOUNDARY/WARM
FRONT MONDAY AFTERNOON WILL TEND TO BE MORE QUASI-LINEAR IN
NATURE AS DEEP LAYER SHEAR REMAINS NEARLY PARALLEL TO THIS
BOUNDARY WITH LITTLE IN THE WAY OF A CAP IN PLACE. HEAVY RAINFALL
POTENTIAL IS CERTAINLY THERE DUE TO THE POTENTIAL FOR STORMS TO
TRAIN OVER ONE ANOTHER/S TRACK NEAR THE WARM FRONT. A MORE
DISCRETE MODE MAY BE EXPECTED ALONG THE DRYLINE MONDAY
AFTERNOON...HOWEVER THIS BOUNDARY IS EXPECTED TO BE PLACED WELL
WEST OF THE CWA. IT IS POSSIBLE FOR DISCRETE STORMS/SUPERCELLS TO
DEVELOP OUT WEST AND THEN MOVE EAST INTO THE CWA LATE MONDAY
AFTERNOON. STORMS WILL INCREASE IN COVERAGE MONDAY EVENING AS THE
ENTIRE STORM SYSTEM BEGINS TO MOVE NORTHEAST AND A COLD FRONT
MOVES THRU THE AREA ONCE AGAIN. UNLIKE TODAY...THIS FRONT IS
EXPECTED TO MOVE ALL THE WAY THRU NORTH TX BY TUESDAY MORNING.
FORCING ALONG THE MOVING COLD FRONT WILL ONCE AGAIN PROMOTE
QLCS/MULTICELL ACTIVITY DEPENDING ON POTENTIAL INSTABILITY AFTER
SUNSET.
FOR MONDAY AFTERNOON...STORMS NEAR THE WARM FRONT WILL CONTINUE TO
HAVE A PRIMARILY LARGE HAIL SEVERE TSTM THREAT WITH ENHANCED
DAMAGING WIND AND TORNADO POTENTIAL FOR ANY AREAS THAT RECEIVE A
FEW HRS OF SUNSHINE. IF DISCRETE SUPERCELLS ARE ABLE TO ORGANIZE
TO OUR WEST...THESE WOULD HAVE A MORE PROMINENT TORNADO AND
DAMAGING WIND THREAT AS WELL AS AN ATTENDANT LARGE HAIL. UNLESS
THIS ACTIVITY IS ABLE TO MOVE INTO THE CWA OR DEVELOP IN THE WAA
REGIME AWAY FROM FRONTAL BOUNDARIES BEFORE SUNSET...THE OVERALL
TORNADO POTENTIAL MAY BE LOW MONDAY AFTERNOON AND EVENING. THESE
DETAILS WILL BE DIFFICULT TO RESOLVE UNTIL TOMORROW WHEN
CONFIDENCE IS HIGHER ON THE PLACEMENT OF SYNOPTIC FEATURES.
EXTENDED...DID NOT MAKE SIGNIFICANT CHANGES TO THE EXTENDED.
BEHIND THE COLD FRONT WE SHOULD SEE A FEW DAYS OF DRY WEATHER
AHEAD OF THE NEXT POWERFUL SHORTWAVE TROUGH. THIS TROUGH IS
EXPECTED TO MOVE INTO THE SOUTHERN PLAINS FRIDAY AFTERNOON OR
FRIDAY NIGHT. 00Z GUIDANCE WAS IN FAIRLY GOOD AGREEMENT ON THE
TIMING OF THIS FEATURE...AND POPS WILL NEED TO BE INCREASED IF
THIS CONSENSUS REMAINS IN TACT MOVING FORWARD. FOR NOW HAVE BROAD
BRUSHED 20 AND 30 POPS FOR FRIDAY AND FRIDAY NIGHT. CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 62 75 61 70 46 / 50 80 90 50 10
WACO, TX 68 80 64 76 45 / 40 50 80 60 10
PARIS, TX 63 74 62 69 45 / 60 80 90 80 10
DENTON, TX 55 71 56 67 41 / 50 80 90 40 5
MCKINNEY, TX 60 74 60 69 43 / 50 80 90 50 10
DALLAS, TX 64 77 63 70 48 / 50 80 90 50 10
TERRELL, TX 67 79 65 72 46 / 50 60 90 70 10
CORSICANA, TX 68 81 68 75 48 / 50 40 80 80 10
TEMPLE, TX 68 82 66 78 46 / 30 30 70 70 10
MINERAL WELLS, TX 55 72 53 69 40 / 40 80 90 30 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25/75
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1048 AM CST SUN NOV 20 2011
.UPDATE...
COLD FRONT HAS MOVED INTO THE WESTERN METROPLEX AS OF 10 AM PER
SURFACE OBS AND RADAR SIGNATURE...WHICH IS MORE IN LINE WITH THE
NAM AND RUC MODELS. HAVE ADJUSTED GRIDS TO REFLECT ITS CURRENT
POSITION AND A SLOW PROGRESSION TO THE SOUTHEAST THROUGH MID
AFTERNOON. MAY REACH A CANTON TO LAMPASAS LINE BY 6 PM THIS
EVENING. MAX TEMPS...HOURLY TEMP...DEWPOINT AND WIND GRIDS WERE
ALSO ADJUSTED THROUGH MID AFTERNOON.
BRIEF LOOK AT THE LATEST GFS AND THE EARLIER NAM/RUC SERIES SHOW A
DIFFERENCE IN THE FRONTAL POSITION OVER THE NEXT 24 HOURS...WHICH
RESULTS IN A LOCATION DIFFERENCE IN WHERE CONVECTION/RAIN WILL
OCCUR THIS AFTERNOON AND OVERNIGHT. SINCE THE NAM/RUC HAVE THE
BEST INITIALIZATION OF THE FRONT...WILL CONTINUE TO FAVOR THEIR
PRECIPITATION PROCESS ALONG AND AHEAD OF THE THE FRONT THIS
AFTERNOON AND TONIGHT. THE PREVIOUS FORECAST HAD THIS APPROACH
BUILT INTO IT...THUS DO NOT FEEL A NEED TO ADJUST TIMING OR
LOCATIONS OF PRECIPITATION IN THIS UPDATE. EVEN THE FORECAST FOR
MONDAY THROUGH MONDAY NIGHT SEEMS ON TRACK WITH THIS MORNING
MODEL RUNS. ONE THING THAT COULD CHANGE IN THE AFTERNOON PACKAGE
WOULD BE THE TIMING FOR ENDING THE RAIN WEST TO EAST ON TUESDAY.
75
&&
.AVIATION...
LOW CLOUDS WILL BE PRESENT THROUGH MOST OF THIS FORECAST CYCLE AS A
COLD FRONT ENCROACHES AND THEN STALLS NEAR THE METROPLEX TODAY.
ONE OF THE MANY CHALLENGES TO THIS FORECAST IS HOW FAR SOUTHEAST
THE FRONT WILL MAKE IT BEFORE COMING TO REST...THEN WHEN IT WILL
LIFT NORTH AS THE WEST COAST UPPER LOW DEEPENS AND APPROACHES THE
REGION. A MODEL BLEND SEEMS MOST LOGICAL AT THIS TIME FOR FRONTAL
POSITION AND RESPECTIVE WIND FORECAST AT THE AREA TERMINALS. NAM
AND RUC ARE WELL AHEAD OF THE GFS ON SOUTHEASTWARD MOVEMENT OF THE
BOUNDARY...BUT APPEAR TO HAVE INITIALIZED ITS POSITION TOO FAR
SOUTHEAST. GFS JUST SEEMS TOO SLOW ON THE FORWARD PROGRESS. FOR
THIS FORECAST SET...WILL CONTINUE WITH THE IFR CIGS UNTIL MID-LATE
MORNING WITH VEERING WINDS AHEAD OF THE FRONT. MVFR CONDITIONS
THEN EXPECTED THE REST OF THE DAY AND WILL ADVERTISE FROPA AT OR
JUST BEFORE NOON LOCAL FOR THE METRO AREA TAF SITES. WILL INDICATE
VEERING WINDS AT ACT BUT THINK THE BOUNDARY MAY BECOME STATIONARY
BEFORE REACHING THE ACT TERMINAL. FRONT WILL THEN LIFT NORTH
TOMORROW MORNING BRINGING SE WINDS AREA-WIDE.
WILL INCLUDE VCSH BEGINNING MIDDAY TODAY. FEEL THE BEST CHANCES
FOR THUNDERSTORMS WILL BE TONIGHT AS OVERALL ASCENT INCREASES AND
THE FRONT PROVIDES FOCUS FOR DEVELOPMENT. CB IS POSSIBLE LATE THIS
AFTERNOON...BUT WITH THE PRESENCE OF A CAP THROUGH MOST OF THE DAY
WILL HOLD OFF MENTION OF CB UNTIL 21/02Z WHEN LOW LEVEL JET BEGINS
TO MATERIALIZE AND ELEVATED TS BECOME MORE LIKELY. 30
&&
.PREV DISCUSSION... /ISSUED 508 AM CST SUN NOV 20 2011/
EARLY MORNING WATER VAPOR IMAGERY DEPICTED SHORTWAVE TROUGHS OVER
THE NORTHERN CONUS ROCKIES...OVER THE BAJA PENINSULA AND JUST OFF
THE NORTHERN CA COAST. A PLUME OF TROPICAL PACIFIC MOISTURE WAS
STREAMING OVER THE SOUTHERN ROCKIES AND OVER THE SOUTHERN PLAINS.
A COLD FRONT CHARACTERIZED BY A STRONG LOW LEVEL BAROCLINIC ZONE
REMAINED JUST TO THE NORTHWEST OF THE CWA AS OF 09Z...AND WAS
LOCATED APPROXIMATELY ALONG AN ARDMORE TO THROCKMORTON LINE.
ALTHOUGH THE FRONT HAS SLOWED DOWN SIGNIFICANTLY OVERNIGHT...IT
CONTINUES TO PUSH SOUTHEAST EARLY THIS MORNING AND WILL LIKELY
ENTER THE FAR NORTHWESTERN COUNTIES OF OUR FORECAST AREA BY 12Z.
TEMPERATURES FALL RAPIDLY BEHIND/NORTH OF THE FRONT WITH A 09Z
TEMPERATURE OF 61 AT BOWIE AND ONLY 46 AT WICHITA FALLS.
TODAY AND TONIGHT...THE BAJA SHORTWAVE TROUGH IS EXPECTED TO MOVE
QUICKLY NORTHEAST DURING THE DAY TODAY AND IS EXPECTED TO BE
LOCATED OVER THE CENTRAL PLAINS BY EARLY THIS EVENING. THIS FAST
MOVING BUT SOMEWHAT WEAK TROUGH WILL SPREAD SOME LARGE SCALE
FORCING FOR ASCENT OVER THE SOUTHERN PLAINS TODAY AHEAD OF THE
COLD FRONT. THE TROUGH ITSELF IS EXPECTED TO REMAIN WELL TO THE
NORTH OF THE CWA...SO IT WILL LIKELY NOT PLAY A SIGNIFICANT ROLE IN
PRECIPITATION CHANCES DURING THE PERIOD. TODAY/S PRIMARY FORECAST
CHALLENGE IS WITH REGARDS TO CONVECTIVE INITIATION ALONG THE COLD
FRONT...WHICH IS EXPECTED TO STALL OUT SOMEWHERE OVER NORTH TX BY
EARLY THIS AFTERNOON.
ONE CHALLENGE REGARDING CONVECTIVE INITIATION THIS AFTERNOON IS
FORECASTING WHERE THE FRONT WILL STALL OUT. 00 AND 06Z GUIDANCE
HAS FAILED TO COME UP WITH A CONSENSUS POSITION OF THE STALLED OUT
FRONT. THE COARSER RESOLUTION GUIDANCE INDICATES THAT THE FRONT
WILL STALL OUT NEAR THE DFW METROPLEX WHILE THE HIGHER RESOLUTION
GUIDANCE INDICATES THAT THE FRONT WILL MAKE IT AS FAR SOUTHEAST AS
A SULPHUR SPRINGS TO HILLSBORO TO GOLDTHWAITE LINE. NEITHER
SOLUTION INITIALIZED THE CURRENT POSITION OF THE FRONT
PERFECTLY...SO OPTED TO GO WITH A BLEND AND JUST PUSHED THE FRONT
FURTHER SOUTHEAST THAN PREVIOUS FORECAST HAD INDICATED FOR THIS
AFTERNOON. THINK THAT BEST PRECIPITATION CHANCES WILL REMAIN ALONG
THE FRONTAL BOUNDARY FOR THIS AFTERNOON...SO ADJUSTED POPS
ACCORDINGLY TAKING THE HIGHER AXIS OF 40/50 POPS A BIT FURTHER
SOUTHEAST FOR THIS AFTERNOON AND THIS EVENING.
THE OTHER CHALLENGE REGARDING CONVECTIVE INITIATION TODAY IS
IDENTIFYING A STRONG FORCING MECHANISM. THE STALLED OUT COLD FRONT
IS THE OBVIOUS FEATURE IN PLAY BUT THE LIMITING FACTOR REGARDING
FORCING ALONG THE FRONT IS THE FACT THAT IT IS EXPECTED TO BE
STATIONARY BY THIS AFTERNOON. WITHOUT MOVEMENT THERE WILL NO
FORCED CONVECTION OUT AHEAD OF THE FRONT ASSOCIATED WITH DYNAMIC
PRESSURE PERTURBATIONS. THE PRIMARY FORCING MECHANISM ASSOCIATED
WITH THE FRONT THEN APPEARS TO BE FRONTOGENESIS WHICH IS TYPICALLY
MAXIMIZED BEHIND THE LEADING EDGE OF THE SURFACE FRONT. MOST SREF
ENSEMBLE MEMBERS DEPICT A LOW LEVEL CAPPING INVERSION IN PLACE
OVER NORTH TX THIS AFTERNOON. WHILE WE WILL HAVE SOME MODEST LOW
LEVEL WARM AIR ADVECTION SOUTH OF THE FRONTAL BOUNDARY TODAY THE
PRESENCE OF THIS CAP /ASSUMING IT EXISTS/ SHOULD LIMIT THE
INITIATION OF TSTM ACTIVITY TO THE IMMEDIATE VICINITY OF THE FRONT.
WITH THIS IN MIND NARROWED THE BAND 30 TO 50 POPS TODAY TO THOSE
LOCATIONS WHERE THE FRONT MAY REASONABLY STALL OUT. DID NOT GO ANY
HIGHER THAN 50 POPS IN THE CWA THRU 00Z AS ALL CONVECTION ALLOWING
GUIDANCE KEEPS TSTM ACTIVITY OUT OF NORTH TX THIS AFTERNOON WHILE
ALL OTHER GUIDANCE INDICATES DEVELOPING CONVECTION ALONG THE FRONT
BETWEEN 21 TO 00Z. THE LACK OF LARGE SCALE FORCING FOR ASCENT
TENDS TO FAVOR A SLOW LIFTING OR STRONGER CAP SO WILL REMAIN
CAUTIOUS WITH REGARDS TO POPS UNTIL 12Z UPPER AIR DATA COMES IN AS
WELL AS AIRCRAFT DATA SOUNDING DATA LATER THIS MORNING.
IF TSTMS ARE ABLE TO INITIATE ALONG THE FRONT THIS
AFTERNOON...THERE IS A CHANCE THAT THEY WILL BECOME SEVERE. SREF
MEAN SURFACE BASED CAPE VALUES ARE AROUND 1000 J/KG SOUTH OF THE
FRONT TODAY AND ALL OPERATIONAL GUIDANCE ADVERTISES AT LEAST THIS
MUCH POTENTIAL INSTABILITY. DEEP LAYER SHEAR IS EXPECTED TO BE
AROUND 40 TO 50 KTS THIS AFTERNOON WHICH WOULD SUPPORT AN
ORGANIZED CONVECTIVE MODE. DEW POINT VALUES THIS MORNING ARE
EXCEPTIONALLY HIGH FOR NOVEMBER...WITH DEW POINTS IN THE LOWER 70S
OBSERVED FROM HEARNE SOUTHEAST TO THE GULF COAST. WE WOULD NEED
JUST A FEW BREAKS IN THE LOW CLOUD COVER THIS AFTERNOON TO SEE
CAPE VALUES JUMP UP ABOVE 1000 J/KG. BECAUSE CLOUDS ARE EXPECTED
TO HOLD IN FOR MUCH OF THE DAY...OVERALL TORNADO POTENTIAL IS LOW
DUE TO POOR LOW LEVEL LAPSE RATES LIMITING VORTEX STRETCHING
POTENTIAL. LARGE HAIL LOOKS TO BE THE PRIMARY THREAT IN THIS
ENVIRONMENT WITH THE DAMAGING WIND AND TORNADO POTENTIAL PERKING
UP IN ANY AREAS THAT SEE A FEW HOURS OF SUNSHINE TODAY. WOULD
EXPECT A LARGELY LINEAR/QLCS STORM MODE AS DEEP LAYER SHEAR
VECTORS ARE EXPECTED TO BE NEARLY PARALLEL TO THE STATIONARY
FRONT.
TSTM ACTIVITY IS EXPECTED TO INCREASE IN COVERAGE TONIGHT AS THE
SHALLOW COLD FRONT INTERACTS WITH THE DEVELOPING LOW LEVEL JET.
THE LOW LEVEL JET IS EXPECTED TO RAMP UP IN ADVANCE OF THE NEXT
APPROACHING SHORTWAVE TROUGH WHICH IS MUCH STRONGER THAN THE BAJA
TROUGH. THE COLD FRONT WILL EFFECTIVELY STEEPEN LOW LEVEL
ISENTROPIC SURFACES ALLOWING FOR SIGNIFICANT ISENTROPIC LIFT
AFTER MIDNIGHT AS THE LLJ RIDES OVER THIS BOUNDARY. THIS FORCING
IS MUCH MORE BROAD THAN THE NARROW FRONTOGENETIC FORCING ALONG THE
FRONT...SO WENT AHEAD AND SPREAD POPS OUT OVER MUCH OF NORTH TX
LATE OVERNIGHT AND THRU MONDAY MORNING AS THE FRONT GRADUALLY
LIFTS BACK NORTH MONDAY MORNING. STORMS SUNDAY NIGHT WILL LIKELY
BE ELEVATED IN NATURE AND SHOULD ONLY POSE A LOWER END SEVERE HAIL
THREAT.
MONDAY AFTERNOON THRU TUESDAY...THE TROUGH THAT CURRENTLY RESIDES
OFF THE NORTHERN CA COAST WILL MOVE THRU THE SOUTHERN PLAINS LATE
MONDAY AFTERNOON THRU THE EVENING HRS. THIS SHOULD RESULT IN
WIDESPREAD TSTM ACTIVITY THRU MUCH OF THE REGION DURING THIS
PERIOD. WITH STRONG FORCING FOR ASCENT ASSOCIATED WITH THE
POWERFUL UPPER TROUGH WENT AHEAD WITH SREF SUGGESTED POPS DUE TO
THE STRONG SYNOPTIC SIGNALS IN PLACE.
FOR OUR CWA...MOST CONFIDENT IN TSTM ACTIVITY NEAR ANY FRONTAL
BOUNDARY DURING THE PERIOD SO HAVE PLACED 80 POPS OR HIGHER NEAR
THE EXPECTED POSITION OF SYNOPTIC FRONTS. ANY STORMS THAT DEVELOP
MONDAY AFTERNOON OR EVENING WILL HAVE THE POTENTIAL TO BECOME
SEVERE WITH DEEP MOISTURE AND EVEN STRONGER SHEAR IN PLACE THAN
WHAT IS EXPECTED FOR SUNDAY AFTERNOON. PRIMARY SEVERE
THUNDERSTORM HAZARDS WILL BE DEPENDENT UPON WHERE FRONTAL
BOUNDARIES LIE AND WHERE STORMS DEVELOP. WHILE THE CONFIDENCE OF
TSTMS OCCURRING IS HIGH...THE CONFIDENCE REGARDING THESE DETAILS
IS FAIRLY LOW AT THIS TIME.
STORMS THAT DEVELOP ALONG THE RETREATING FRONTAL BOUNDARY/WARM
FRONT MONDAY AFTERNOON WILL TEND TO BE MORE QUASI-LINEAR IN
NATURE AS DEEP LAYER SHEAR REMAINS NEARLY PARALLEL TO THIS
BOUNDARY WITH LITTLE IN THE WAY OF A CAP IN PLACE. HEAVY RAINFALL
POTENTIAL IS CERTAINLY THERE DUE TO THE POTENTIAL FOR STORMS TO
TRAIN OVER ONE ANOTHER/S TRACK NEAR THE WARM FRONT. A MORE
DISCRETE MODE MAY BE EXPECTED ALONG THE DRYLINE MONDAY
AFTERNOON...HOWEVER THIS BOUNDARY IS EXPECTED TO BE PLACED WELL
WEST OF THE CWA. IT IS POSSIBLE FOR DISCRETE STORMS/SUPERCELLS TO
DEVELOP OUT WEST AND THEN MOVE EAST INTO THE CWA LATE MONDAY
AFTERNOON. STORMS WILL INCREASE IN COVERAGE MONDAY EVENING AS THE
ENTIRE STORM SYSTEM BEGINS TO MOVE NORTHEAST AND A COLD FRONT
MOVES THRU THE AREA ONCE AGAIN. UNLIKE TODAY...THIS FRONT IS
EXPECTED TO MOVE ALL THE WAY THRU NORTH TX BY TUESDAY MORNING.
FORCING ALONG THE MOVING COLD FRONT WILL ONCE AGAIN PROMOTE
QLCS/MULTICELL ACTIVITY DEPENDING ON POTENTIAL INSTABILITY AFTER
SUNSET.
FOR MONDAY AFTERNOON...STORMS NEAR THE WARM FRONT WILL CONTINUE TO
HAVE A PRIMARILY LARGE HAIL SEVERE TSTM THREAT WITH ENHANCED
DAMAGING WIND AND TORNADO POTENTIAL FOR ANY AREAS THAT RECEIVE A
FEW HRS OF SUNSHINE. IF DISCRETE SUPERCELLS ARE ABLE TO ORGANIZE
TO OUR WEST...THESE WOULD HAVE A MORE PROMINENT TORNADO AND
DAMAGING WIND THREAT AS WELL AS AN ATTENDANT LARGE HAIL. UNLESS
THIS ACTIVITY IS ABLE TO MOVE INTO THE CWA OR DEVELOP IN THE WAA
REGIME AWAY FROM FRONTAL BOUNDARIES BEFORE SUNSET...THE OVERALL
TORNADO POTENTIAL MAY BE LOW MONDAY AFTERNOON AND EVENING. THESE
DETAILS WILL BE DIFFICULT TO RESOLVE UNTIL TOMORROW WHEN
CONFIDENCE IS HIGHER ON THE PLACEMENT OF SYNOPTIC FEATURES.
EXTENDED...DID NOT MAKE SIGNIFICANT CHANGES TO THE EXTENDED.
BEHIND THE COLD FRONT WE SHOULD SEE A FEW DAYS OF DRY WEATHER
AHEAD OF THE NEXT POWERFUL SHORTWAVE TROUGH. THIS TROUGH IS
EXPECTED TO MOVE INTO THE SOUTHERN PLAINS FRIDAY AFTERNOON OR
FRIDAY NIGHT. 00Z GUIDANCE WAS IN FAIRLY GOOD AGREEMENT ON THE
TIMING OF THIS FEATURE...AND POPS WILL NEED TO BE INCREASED IF
THIS CONSENSUS REMAINS IN TACT MOVING FORWARD. FOR NOW HAVE BROAD
BRUSHED 20 AND 30 POPS FOR FRIDAY AND FRIDAY NIGHT. CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 74 62 75 61 70 / 30 50 80 90 50
WACO, TX 79 68 80 64 76 / 40 40 50 80 60
PARIS, TX 79 63 74 62 69 / 50 60 80 90 80
DENTON, TX 69 55 71 56 67 / 30 50 80 90 40
MCKINNEY, TX 76 60 74 60 69 / 30 50 80 90 50
DALLAS, TX 75 64 77 63 70 / 30 50 80 90 50
TERRELL, TX 78 67 79 65 72 / 40 50 60 90 70
CORSICANA, TX 80 68 81 68 75 / 40 50 40 80 80
TEMPLE, TX 81 68 82 66 78 / 20 30 30 70 70
MINERAL WELLS, TX 64 55 72 53 69 / 30 40 80 90 30
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/75
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
304 PM CST SUN NOV 20 2011
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
304 PM CST SUN NOV 20 2011
THE MAIN FOCUS GOING INTO MID WEEK IS ON THE POTENTIAL FOR RAIN ON
TUESDAY AS A STORM SYSTEM MOVES THROUGH THE REGION.
CURRENTLY...A RIDGE OF HIGH PRESSURE EXTENDS FROM SOUTHERN ONTARIO
TOWARD SOUTHERN MINNESOTA. SOME LOW LEVEL STRATUS HAS LINGERED
ACROSS MUCH OF THE REGION TODAY DUE TO MOISTURE STUCK UNDER A
900MB INVERSION ON THE SOUTHEAST SIDE OF THIS RIDGE. THIS STRATUS
HAS BEEN SLOW TO ERODE TODAY WITH THE CORE OF THIS RIDGE SHIFTING
EAST INTO THE GREAT LAKES..THOUGH IT HAS LOOKED A BIT MORE
CELLULAR ON THE LAST FEW VISIBLE SCANS. WITH INCREASING LOW LEVEL
SUBSIDENCE...SKIES ARE EXPECTED TO CLEAR FROM WEST TO EAST THIS
EVENING WITH 20.18Z RUC FORECAST SOUNDINGS SHOWING THE LOW LEVEL
RH DECREASING THIS EVENING. THOUGH SKIES MAY BRIEFLY CLEAR THIS
EVENING...ADDITIONAL MID TO UPPER LEVEL CLOUD COVER IS EXPECTED TO
MOVE IN TONIGHT AHEAD OF A WEAK MID TO UPPER LEVEL WAVE THAT WILL
LIFT OUT OF THE SOUTHERN PLAINS AND HELP TO BRING SKY COVER BACK UP.
THE FOCUS THEN GOES TO TUESDAY AS A CLOSED LOW CURRENTLY ALONG THE
CALIFORNIA COAST PROPAGATES THROUGH THE FOUR CORNERS REGION TOMORROW
BEFORE ENDING UP NEAR THE SOUTHERN GREAT LAKES ON TUESDAY. THE
TREND WITH THE 20.12Z GUIDANCE HAS BEEN TO GO TOWARD HAVING A
STRONGER MID LEVEL TROUGH COME THROUGH THAT BRINGS RAIN TO THE
REGION. THE 20.12Z NAM AND ECMWF ARE THE FIRST TWO FORMS OF
GUIDANCE TO SHOW THIS PROGRESSION WHILE THE 20.12Z GFS KEEPS THE
BULK OF THE PRECIPITATION TO THE SOUTHEAST. THE PATH OF THE
SURFACE LOW DOES NOT LOOK MUCH DIFFERENT THAN WHAT PREVIOUS RUNS
HAVE SHOWN...BUT THE STRONGER MID LEVEL TROUGH LEADS TO A LARGER
AREA OF MID LEVEL QG FORCING AND IN TURN A LARGER AREA OF
PRECIPITATION. THOUGH SURFACE TEMPERATURES ARE EXPECTED TO BE IN
THE 30S TO LOW 40S...20.12Z NAM BUFKIT SOUNDINGS LOOK WARM ENOUGH
IN THE LOWEST 4KFT TO KEEP THE PRECIPITATION TYPE AS RAIN FOR THIS
EVENT. AT THIS POINT...IT APPEARS THAT RAIN WOULD START UP TUESDAY
MORNING AND END BY TUESDAY EVENING.
OTHER THAN THAT...TEMPERATURES WILL REMAIN SEASONAL IN THE 40S
FOR HIGHS AND 20S FOR LOWS WITH WEAK LOW LEVEL WARM AIR ADVECTION
EXPECTED THROUGH MID WEEK. 850MB TEMPERATURES WILL GRADUALLY RISE
FROM -2C TONIGHT TO AROUND 1C ON MONDAY...THEN TO 3-5C ON
WEDNESDAY AS A WARMER AIR MASS BEGINS TO SPREAD INTO THE REGION.
.LONG TERM...WEDNESDAY NIGHT INTO SUNDAY
304 PM CST SUN NOV 20 2011
CONDITIONS ARE LOOKING IDEAL FOR THE START OF THE HOLIDAY TRAVEL
SEASON WITH WARM SOUTHWESTERLY FLOW SETTING UP WEDNESDAY NIGHT
INTO FRIDAY WITH A SURFACE RIDGE IN THE SOUTHEAST US AND THE NEXT
LOW PRESSURE SYSTEM FORMING IN SOUTHERN CANADA. PERHAPS THE ONLY
CONCERN IS WITH HOW WINDY IT WILL BE ON THANKSGIVING WITH 20.12Z
GFS SOUNDINGS SHOWING SOUTH TO SOUTHWEST WINDS OF AROUND 15-17KTS
IN THE HIGHER TERRAIN WITH GUSTS UP TO AROUND 25-30KTS. BEYOND
THIS...925-850MB MOISTURE TRANSPORT WILL BE ON THE INCREASE AHEAD
OF THE NEXT TROUGH AND COLD FRONT THAT WILL MOVE INTO THE REGION
ON FRIDAY. THERE ARE SOME TIMING DIFFERENCES BETWEEN THE 20.12Z
GFS AND ECMWF WITH THE GFS BRINGING THIS PRECIPITATION AND FRONT
IN FASTER THAN THE ECMWF. THE ECMWF ALSO SPINS UP A SECONDARY
SURFACE LOW ON FRIDAY NIGHT INTO SATURDAY AND LINGERS THE
PRECIPITATION LONGER THAN WHAT THE GFS SHOWS. AT THIS POINT IT
APPEARS THAT THE THERMAL PROFILE WOULD BE WARM ENOUGH TO KEEP THE
PRECIPITATION TYPE IN ALL LIQUID FORM UNTIL PERHAPS THE VERY END
OF THE EVENT WHEN THE COLDER AIR MOVES IN.
&&
.AVIATION...THROUGH 18Z MONDAY
1159 AM CST SUN NOV 20 2011
IFR/MVFR STRATUS A BIT PROBLEMATIC TODAY WITH LOW LEVEL MOISTURE
TRAPPED BELOW PERSISTENT SUBSIDENCE INVERSION. THE RIDGE AXIS THAT
IS PRODUCING THIS SUBSIDENCE WILL SHIFT EAST OF THE REGION THIS
EVENING...ALLOWING FOR SOUTHEAST WINDS AND A SHIFT NORTHWARD OF THE
STRATUS OUT OF THE KRST/KLSE TAF SITE WHILE DISSIPATING AT THE SAME
TIME. THESE CLOUDS WILL THEN BE REPLACED WITH MID/HIGH CLOUDS AFTER
MIDNIGHT AHEAD OF A WEAK MID-LEVEL MOVING EAST OUT OF THE
INTERMOUNTAIN WEST. BASES OF THESE CLOUD ARE EXPECTED TO BE AOA
10KFT AFTER MIDNIGHT...LOWERING TO 7-8KFT AFTER 09Z. MODELS SHOW
THIS MID CLOUD MOVING NORTH/EAST OF THE TAF SITES MONDAY AFTERNOON.
SURFACE WINDS WILL BE WEAK FROM THE SOUTHEAST OVERNIGHT...THEN
EVENTUALLY VEER TO THE SOUTHWEST AFTER 18Z MONDAY AND GENERALLY
REMAINING BELOW 10KT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
304 PM CST SUN NOV 20 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...DAS