FXUS64 KLCH 080432
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
1032 PM CST MON DEC 7 2009
.DISCUSSION...
FRONTAL BOUNDARY HAS REMAINED QUASI-STATIONARY THROUGH THIS
EVENING...AND EXTENDS ACROSS THE NORTHWEST GULF ROUGHLY ALONG A
LINE FROM VERMILION BAY TO JUST NORTH OF PORT MANSFIELD. NOT
SURPRISINGLY...THE MOST VIGOROUS SHOWER ACTIVITY...AND A FEW
THUNDERSTORMS...HAVE BEEN ALONG AND NEAR THE FRONT. NORTH OF THE
BOUNDARY...THE 00Z KLCH RAOB SHOWED A SHALLOW COOL LAYER BENEATH
AN INVERSION BASED AROUND 650 FT AGL. THE BASE OF THIS INVERSION IS
LOCATED AROUND 1700 FT AGL ON THE KSHV SOUNDING...SO THIS NICELY
DEMONSTRATES THE SHALLOW-SLOPING NATURE OF THE NEAR SURFACE COOL
LAYER. ISENTROPIC LIFT COURTESY OF A TROUGH OVER THE SOUTHWESTERN
CONUS AND ITS ASSOCIATED JET IS RESULTING IN WARM AND MOIST AIR
RIDING ATOP THIS SHALLOW COOL LAYER...WITH THE RESULT BEING AREAS
OF MAINLY LIGHT TO MODERATE RAINFALL. EXPECT THAT THIS WILL
PERSIST THROUGH THE OVERNIGHT HOURS...THUS HIGH POPS CONTINUE TO
LOOK FINE.
VISIBILITY HAS IMPROVED OVER THE AREA SINCE EARLIER TODAY...AND
ALTHOUGH LOW CEILINGS AND SOME VISIBILITY RESTRICTIONS ARE STILL
ANTICIPATED...AREAS OF DENSE FOG ARE NOT. THUS...THE ADVISORIES FOR THE
COASTAL AREAS AND ADJACENT BODIES OF WATER WERE CANCELLED. WILL
STILL HAVE TO MONITOR THE NEARSHORE WATERS AS THE FRONT RETREATS
NORTHWARD AND HIGHER DEWPOINT AIR IS ADVECTED OVER COOLER SEA
SURFACE TEMPERATURES...WHICH MAY RESULT IN THE FOG REFORMING
TOWARD MORNING. WILL LET THE MID SHIFT TAKE ANOTHER LOOK AT THIS
POTENTIAL.
FORECAST FOR TOMORROW CONTINUES TO LOOK ON TARGET AS WELL...WITH
BREEZY AND WARM CONDITIONS EXPECTED IN THE NORTHWARD EXPANDING
WARM SECTOR. THE THREAT OF SEVERE WEATHER STILL LOOKS
WARRANTED...AS ATMOSPHERIC SHEAR PROFILES WILL BE QUITE SUPPORTIVE
OF A DAMAGING WIND AND/OR TORNADO THREAT...THOUGH INSTABILITY
APPEARS TO BE THE MAIN LIMITING FACTOR PRECLUDING AN EVEN
GREATER RISK. THE MID SHIFT MAY ALSO NEED TO CONSIDER A LAKE WIND
ADVISORY...WITH H925 WINDS PROGGED AT 40 TO 50 KNOTS OVER THE
AREA...AND FAIRLY CLOSELY ALIGNED WITH THE SFC WINDS.
ALL UPDATED PRODUCTS ALREADY SENT.
&&
.PREV DISCUSSION... /ISSUED 628 PM CST MON DEC 7 2009/
AVIATION...WHAT A MODERATE RAIN COVERS TERMINALS LCH, LFT AND
ARA WHILE LIGHT RAIN IS MOVING INTO THE AEX AREA AND RAIN HAS
TAPERED OFF TO LIGHT AROUND BPT. IFR CIGS ARE THE RULE WITH MVFR
VIS. THERE COULD BE COME LOWERING OF BOTH CIGS AND VIS TO LIFR
LATE THIS EVENING. THE CULPRIT LOOKS TO BE A RETREATING BOUNDARY
AS A WARM FRONT EXTENDING FROM OFF THE SOUTH TEXAS AND UPPER TEXAS COAST
INTO ATCHAFALAYA BAY. THE WARM FRONT WILL TAKE ITS TIME LIFTING
DUE TO SOUTHWESTERLY FLOW ALOFT AND WILL BE PASSING NORTH OF THE
TERMINALS BY TUESDAY MORNING. A FEW TSTMS WILL BE POSSIBLE IN THE
MORNING UNTIL DRIER AIR BEHIND THE FRONT TAPERS OFF THE TSTMS.
STRONG SOUTH WINDS IN THE WARM SECTOR AFTER FRONTAL PASSAGE ON TUESDAY.
EXPECTING IMPROVEMENT TO MVFR CIGS WITH GOOD VSBY TUESDAY AFTERNOON.
SWEENEY
PREV DISCUSSION... /ISSUED 335 PM CST MON DEC 7 2009/
DISCUSSION...
WARM ADVECTION IS COMMENCING ACROSS THE SOUTHERN PORTION OF THE
FORECAST AREA THIS AFTERNOON WITH WIDESPREAD SHOWERS AND ISOLATED
THUNDERSTORMS DEVELOPING JUST OFFSHORE AND THIS ACTIVITY WILL
CONTINUE TO OVERSPREAD THE REGION FROM SOUTHWEST TO NORTHEAST
THROUGH THE NIGHT. AS AREA GETS INTO THE WARM SECTOR TOMORROW
SOUTH OF THE WARM FRONT THE WIDESPREAD SHOWERS AND THUNDERSTORMS
WILL BECOME MORE SCATTERED IN THE LATE MORNING AND AFTERNOON AS
PRE-FRONTAL TROUGH APPROACHES THE REGION IN THE AFTERNOON...SOME
POTENTIAL FOR SEVERE THUNDERSTORMS IN THE LATE MORNING AND
AFTERNOON. DESPITE STRONG SHEAR FOR SEVERE
THUNDERSTORMS...LIMITING FACTOR WILL BE MEAGER INSTABILITY. MAIN
THREATS FROM ANY SEVERE THUNDERSTORMS WOULD BE DAMAGING WINDS AND
OR TORNADOES. COLD FRONT WORKS THROUGH THE REGION TOMORROW NIGHT
BRINGING AN END TO THE SHOWERS AND THUNDERSTORMS.
ALONG THE COAST...SHELF WATERS ARE IN THE LOWER 60S NEAR THE COAST
AND DEWPOINTS ARE FORECAST TO SURGE INTO THE MID AND UPPER 60S
OVERNIGHT. THIS SHOULD RESULT IN CONTINUED DENSE FOG DEVELOPMENT
OUTSIDE OF SHOWERS AND THUNDERSTORMS AND THIS WILL WORK INTO THE
INLAND AREAS. THUS WILL EXTEND FOG ADVISORY ALONG THE COASTAL
COUNTIES AND PARISHES.
ALSO WITH THE STRONG WARM ADVECTION THIS EVENING AND
OVERNIGHT...EXPECT TEMPERATURES TO FALL EARLY...THEN BECOME STEADY
OR RISE DURING THE OVERNIGHT.
IN THIS PATTERN WEATHER SYSTEMS WILL CONTINUE TO MOVE THROUGH
EVERY TWO TO THREE DAYS AND AT THIS TIME...ONLY DAYS THIS WEEK
THAT DO NOT CURRENTLY HAVE ANY RAIN CHANCES ARE WEDNESDAY AND
THURSDAY. WITH THE EXCEPTION OF TONIGHT AND
TOMORROW...TEMPERATURES WILL BE BELOW NORMAL THROUGH THE REMAINDER
OF THE FORECAST.
MARINE...
WARM MOIST AIR MOVING OVER COOLER SHELF WATERS WILL PRODUCE AREAS
OF DENSE FOG TONIGHT OUTSIDE OF SHOWERS AND THUNDERSTORMS. SMALL
CRAFT SHOULD EXERCISE CAUTION TONIGHT OUT BEYOND 20 MILES AS WINDS
BEGIN TO INCREASE OUT OF THE SOUTH. WINDS WILL CONTINUE TO
INCREASE TUESDAY AND SMALL CRAFT ADVISORIES MAY BE NEEDED FOR
PORTIONS OF THE AREA. THE ISSUE NEAR SHORE WITH THE COOLER WATER
TEMPERATURES...IS WILL THIS PREVENT THE STRONGER WINDS FROM WORKING
TO THE SURFACE TOMORROW.
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 56 73 56 65 / 80 70 20 10
KBPT 55 71 53 65 / 70 60 10 10
KAEX 51 73 52 61 / 70 90 30 10
KLFT 60 75 58 67 / 80 80 30 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...NONE.
&&
$$
13
