AFDLCH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
623 AM CDT MON APR 18 2011

...12Z TAF DISCUSSION...

.AVIATION...
LATEST MICROWAVE SATELLITE IMAGERY SHOWS LOW CLOUDS BLANKET NEARLY
THE ENTIRE FORECAST AREA...BUT CEILINGS VARY GREATLY FROM WEST TO
EAST WITH KBPT AT IFR AND KARA AT VFR. EXPECTING IFR CEILINGS
THROUGH 15Z AT KBPT AND MVFR ELSEWHERE WITH ALL AIRPORTS IMPROVING
TO MVFR/VFR DURING THE LATE MORNING AND EARLY AFTERNOON. SOUTH
WINDS TO BE QUITE STRONG TODAY WITH SPEEDS 12-20 KTS AND GUSTS
18-28 KTS. WINDS WILL DIMINISH SOMEWHAT AFTER SUNSET THIS EVENING
BUT REMAIN STRONG THROUGH THE NIGHT BENEATH 35-40 KT LLJ...WITH
MVFR CEILINGS REDEVELOPING MONDAY EVENING.

05

&&

.PREV DISCUSSION... /ISSUED 521 AM CDT MON APR 18 2011/

DISCUSSION...
FEW CHANGES OF SUBSTANCE MADE TO THE FORECAST GRIDS THIS MORNING.
QUASI-ZONAL FLOW ALOFT PROGGED TO PERSIST THROUGH THE WEEK...WITH
THE PRIMARY STORM TRACK RESIDING WELL TO THE NORTH FROM THE
CENTRAL/SOUTHERN PLAINS TO THE GREAT LAKES. THE DRY AIRMASS
USHERED IN BY THE LAST COLD FRONT HAS BEGUN TO MODIFY...WITH SFC
DEWPOINTS SOME 20 TO 25 DEGREES HIGHER THAN 24 HRS AGO.

STRATUS DEVELOPED OVERNIGHT AS ANTICIPATED...AND CURRENTLY
BLANKETS THE ENTIRE REGION. THESE CLOUDS ARE EXPECTED TO LIFT AND
BECOME MORE SCATTERED AS DAYTIME HEATING GRADUALLY DEEPENS AND
MIXES THE BOUNDARY LAYER. THIS WILL ALSO PERMIT HIGHER WINDS ALOFT
TO REACH THE SURFACE AS GUSTS...WHICH SHOULD TOP OUT AROUND 25 MPH
OR SO DURING THE AFTERNOON HOURS. SUSTAINED SPEEDS ARE PROGGED IN
THE 15 TO 20 MPH RANGE. THIS IS CLOSE TO WIND ADVISORY
CRITERIA...20 MPH...AND I WOULD NOT BE SURPRISED IF A SITE OR TWO
ACHIEVES THIS FOR AN HOUR OR TWO...ESPECIALLY ALONG/SOUTH OF THE
I-10 CORRIDOR. HOWEVER...GIVEN THE BORDERLINE NATURE...WILL NOT
ISSUE AN ADVISORY AT THIS TIME.

DESPITE THE INCREASE IN MOISTURE...AND RELATIVELY STEEP MID LEVEL
LAPSE RATES...MODEL FORECAST SOUNDINGS INDICATE WEST/SOUTHWEST
FLOW ALOFT WILL MAINTAIN A CAPPING INVERSION. ALONG WITH THE
ABSENCE OF ANY FORCING MECHANISM OF NOTE...THIS IS EXPECTED TO
INHIBIT SHOWER AND THUNDERSTORM DEVELOPMENT.

TUESDAY LOOKS TO BE A VIRTUAL REPEAT OF TODAY...WITH ANOTHER NIGHT OF
STRATUS GIVING WAY TO A PARTLY CLOUDY AND BREEZY AFTERNOON. THE PRIMARY
DIFFERENCE I SEE IS THAT THE LLJ IS PROGGED TO BE STRONGER...WHICH
SHOULD RESULT IN HIGHER WINDS BOTH OVERNIGHT AND TUESDAY AFTERNOON.
A WIND ADVISORY APPEARS MORE WARRANTED FOR TUESDAY AFTERNOON THAN
TODAY...BUT THIS IS A LITTLE TO FAR OUT FOR THIS FORECAST PACKAGE.

WEDNESDAY WILL SEE A FRONT ATTEMPT TO SAG INTO THE AREA AS DECENT
SHORTWAVE ENERGY TRAVERSES THE CONUS. CONSENSUS OF GUIDANCE AT
THIS POINT STALLS THE FRONT JUST NORTH OF MY FORECAST AREA...GENERALLY
BETWEEN THE I-20 CORRIDOR AND ALEXANDRIA. FORECAST SOUNDINGS SHOW
ENOUGH EROSION OF THE CAP TO AT LEAST PERMIT THE POTENTIAL FOR
CONVECTION...BUT WITH THE FRONT WEAKENING AND THE BEST UPPER
SUPPORT STAYING WELL TO THE NORTH...THE INHERITED 20 PERCENT
WEDNESDAY/WEDNESDAY NIGHT LOOKS FINE.

TEMPERATURES ARE EXPECTED TO REMAIN WELL ABOVE NORMAL.

WENT DRY FOR THE REMAINDER OF THE WEEK AND THROUGH THE WEEKEND
WITH GLOBAL MODELS INDICATING A BUILDING SE CONUS RIDGE. PATTERN
CHANGE PROGGED FOR NEXT WEEK MAY OFFER SOME HOPE OF MORE
SUBSTANTIAL RAINFALL. KEEP YOUR FINGERS CROSSED.

MARINE...
THE NORTHWEST GULF COAST REGION IS FORECAST TO REMAIN BETWEEN THE
BERMUDA HIGH TO THE EAST...AND MEAN LOW PRESSURE TO THE WEST AND
NORTHWEST. SOUTHERLY WINDS ARE EXPECTED TO REMAIN GENERALLY
MODERATE...BUT SPEEDS WILL FLUCTUATE WITH THE TYPICAL DIURNAL
PATTERN AND AS LOW PRESSURE SYSTEMS OVER THE PLAINS AFFECT THE
PRESSURE GRADIENT.

&&

.PRELIMINARY POINT TEMPS/POPS...
KLCH  81  70  84  70  84 /  10  10  10  10  10
KBPT  82  71  85  72  85 /  10  10  10  10  10
KAEX  84  70  89  71  89 /  10  10  10  10  20
KLFT  85  70  88  70  88 /  10  10  10  10  10

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...SMALL CRAFT EXERCISE CAUTION THROUGH TUESDAY MORNING FOR THE
     FOLLOWING ZONES: CALCASIEU LAKE...COASTAL WATERS FROM
     CAMERON, LA TO HIGH ISLAND, TX OUT 20 NM...COASTAL WATERS
     FROM INTRACOASTAL CITY TO CAMERON, LA OUT 20 NM...COASTAL
     WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY,
     LA OUT 20 NM...SABINE LAKE...VERMILION BAY...WATERS FROM
     CAMERON, LA TO HIGH ISLAND, TX EXTENDING FROM 20 NM TO 60
     NM...WATERS FROM INTRACOASTAL CITY, LA TO CAMERON, LA
     EXTENDING FROM 20 NM TO 60 NM...WATERS FROM LOWER
     ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA EXTENDING FROM
     20 NM TO 60 NM.

&&

$$