549
FXUS64 KLCH 021139
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
539 AM CST TUE DEC 2 2008
AVIATION
PATCHY GROUND FOG AND POSSIBLY SMOKE AT LFT FOR THE
NEXT COUPLE OF HOURS. GROUND BASED RADIATION INVERSION SHOULD
LIFT AT ALL TAF SITES AROUND BY MID-MORNING WITH WEAK SOUTHERLY
RETURN FLOW ON THE BACK SIDE OF THE COLD DOME OF HIGH PRESSURE
MOVING EAST ALONG THROUGH THE MISSISSIPPI DELTA TO THE FLORIDA
PANHANDLE TODAY. RETURN FLOW MOISTURE WILL LAG UNTIL LATE TONIGHT
WITH VFR STRATCU CIGS AROUND 3500 FT INTO BPT AND LCH UNDER THE
FRONTAL INVERSION. LOWER CIGS TO MVFR LEVELS OF 1500 FT FOR AEX
JUST BEFORE DAYBREAK WEDNESDAY.
SWEENEY
PREV DISCUSSION
/ISSUED 411 AM CST TUE DEC 2 2008/
SYNOPSIS...
COLD HIGH PRESSURE SYSTEM ON TOP OF THE FORECAST AREA THIS EARLY
MORNING. THE CLEAR SKIES AND LIGHT WINDS ARE PRODUCING QUITE
CHILLY TEMPERATURES WITH JUST ABOUT EVERYONE EXPERIENCING A LIGHT
FREEZE.
LATEST WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROF EXTENDING
FROM THE EASTERN GREAT LAKES TO THE CENTRAL GULF COAST...MOVING
OFF TO THE EAST...WITH THE NEXT UPPER LEVEL TROF OVER THE
NORTHWEST U.S. DROPPING QUICKLY TO THE SOUTHEAST.
RUA
DISCUSSION...
AFTER A COLD START TEMPERATURES SHOULD REBOUND NICELY TODAY AS
SUNNY SKIES PREVAIL AND SOUTHERLY WINDS BEGIN TO RETURN AS HIGH
PRESSURE MOVES OFF TO THE EAST. WITH THE SOUTHERLY WINDS AND
EXPECTED HIGHER DEWPOINTS...LOW TEMPERATURES TONIGHT ARE EXPECTED
TO BE QUITE A BIT WARMER THAN THE LAST COUPLE OF NIGHTS.
AS THE NORTHWEST U.S. UPPER LEVEL TROF QUICKLY APPROACHES THE
REGION ON WEDNESDAY...LOW PRESSURE IS EXPECTED TO FORM OVER THE
SOUTHERN PLAINS WITH A TIGHT GRADIENT ACROSS THE FORECAST AREA.
THIS WILL ALLOW FOR BREEZY SOUTHERLY WINDS WITH WARM TEMPERATURES.
THE SOUTHERLY BREEZES WILL ALSO QUICKLY RETURN GULF MOISTURE TO
THE FORECAST AREA DURING WEDNESDAY. AS THE UPPER LEVEL TROF
CONTINUES TO MOVE QUICKLY TO THE SOUTHEAST...IT WILL PUSH A COLD
FRONT ACROSS THE FORECAST AREA WEDNESDAY NIGHT...EXITING THE FAR
EASTERN PORTIONS OF THE FORECAST AREA ON EARLY THURSDAY MORNING.
DECENT MOISTURE VALUES FOR THIS TIME OF YEAR ARE PROGGED TO POOL
RIGHT AHEAD OF THE FRONT WITH PWAT VALUES OVER 1.25 INCHES AND
MEAN RH OVER 70 PERCENT. VERY GOOD LOW LEVEL CONVERGENCE IS
PROGGED WITH THIS FRONT AND THIS SHOULD ALLOW IT TO TAP INTO THE
AVAILABLE GULF MOISTURE TO PRODUCE A BAND OF SHOWERS RIGHT ALONG
IT. SURFACE INSTABILITY IS PROGGED TO BE WEAK WITH CAPE VALUES
LESS THAN 500 J/KG AS FRONT MOVES ACROSS. THEREFORE...ONLY EXPECT
ISOLATED THUNDERSTORMS EMBEDDED IN THE CONVECTIVE SHOWER BAND. MID
LEVEL WINDS ARE SHOWN TO BE BETWEEN 45 TO 50 KNOTS AT THIS TIME.
HOWEVER...WITH LOW SURFACE BASED INSTABILITY AND BEST UPPER LEVEL
DIVERGENCE DISPLACED TO THE NORTHEAST...DO NOT EXPECTED ANY
THUNDERSTORMS TO BECOME TOO STRONG. ALSO...WITH CONVECTIVE BAND
MOVING FAIRLY QUICKLY...WOULD NOT EXPECT ANY EXCESSIVE RAINFALL
AMOUNTS...WITH STORM TOTAL QFP RAINFALL AMOUNTS AVERAGING AROUND
1/2 INCH.
DRIER AND COOLER AIR WILL THEN FILTER IN BEHIND THE COLD FRONT FOR
THURSDAY INTO FRIDAY. ZONAL FLOW WITH MODERATING TEMPERATURES IS
EXPECTED INTO THE WEEKEND. A WEAK SHORT WAVE IS EXPECTED TO MOVE
ACROSS LATE MONDAY INTO TUESDAY OF NEXT WEEK WITH A SLIGHT CHANCE
FOR SHOWERS.
RUA
MARINE...
LATEST MSAS ANALYSIS SHOWS WINDS HAVE DECREASE OVER THE COASTAL
WATERS AND THE SMALL CRAFT ADVISORY HAS BEEN ALLOWED TO EXPIRE.
HIGH PRESSURE AT THE SURFACE IS EXPECTED TO QUICKLY MOVE OFF TO
THE EAST TODAY ALLOWING FOR SOUTHERLY WINDS TO RETURN TO THE
COASTAL WATERS. THESE SOUTHERLY WINDS WILL INCREASE TONIGHT INTO
WEDNESDAY AS GRADIENT TIGHTENS IN RESPONSE TO LOW PRESSURE
DEVELOPING OVER THE SOUTHERN PLAINS. SMALL CRAFT ADVISORY
CONDITIONS WILL BE POSSIBLE AFTER MIDNIGHT TONIGHT OVER THE
WESTERN ZONES...THEN OVER THE ENTIRE COASTAL WATERS ON WEDNESDAY.
A COLD FRONT WILL MOVE ACROSS THE COASTAL WATERS WEDNESDAY NIGHT
AND EARLY THURSDAY MORNING. A BAND OF SHOWERS AND A FEW
THUNDERSTORMS WILL ACCOMPANY THE FRONT. STRONG NORTHERLY WINDS
WILL THEN DEVELOP AGAIN BEHIND THE FRONT ON THURSDAY WITH THE
POSSIBILITY OF SMALL CRAFT ADVISORY CONDITIONS.
RUA
PRELIMINARY POINT TEMPS/POPS
KLCH 64 52 75 53 62 / 0 0 10 50 10
KBPT 65 55 74 51 62 / 0 0 20 50 10
KAEX 59 46 73 50 57 / 0 0 10 50 10
KLFT 60 48 73 53 62 / 0 0 10 50 20
LCH WATCHES/WARNINGS/ADVISORIES
LA...NONE.
TX...NONE.
GM...NONE.
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