Tornado Warning 25, NWS Lake Charles, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
1013 AM CDT TUE AUG 12 2008

.UPDATE...

RADAR IMAGERY THIS MORNING SHOWS A LARGE AREA OF RAIN AND EMBEDDED
THUNDERSTORMS MOVING ACROSS NORTHERN ZONES TODAY. WITH ACTIVITY
SO WIDESPREAD AND CONTINUING TO SHIFT EASTWARD...HAVE RAISED POPS
TO 100 PERCENT OVER NORTHERN ZONES FOR TODAY. ALSO ADJUSTED CLOUD
COVER UPWARD AND LOWERED HIGHS SLIGHTLY. FURTHER TO THE
SOUTH...ACTIVITY WILL BE MORE SCATTERED IN NATURE AND THUS HAVE
KEPT POPS IN THE LIKELY CATEGORY. TEMPS WILL ALSO BE WARMER IN
AREAS AWAY FROM THE PRECIP...ESPECIALLY IN SOUTH CENTRAL LOUISIANA
WHERE TEMPS AROUND 90 ARE EXPECTED. HAVE SEEN SOME LOCALLY HEAVY
RAINFALL NORTH OF THE CWA AND WILL CONTINUE TO MENTION IN
ZONES. CONFIDENCE REMAINS LOW ON A WIDESPREAD FLASH FLOOD THREAT
AND WILL NOT ISSUE A FLASH FLOOD WATCH AT THIS TIME.

SPC HAS PLACED ENTIRE CWA IN A SLIGHT RISK...WITH THE MAIN THREAT
BEING DAMAGING WINDS AND ISOLATED TORNADOES. THIS IS DUE TO A VERY
MOIST AIRMASS IN PLACE...SHOWN BY THE 12Z KLCH SOUNDING WHICH HAS
A PWAT OF 2.22 INCHES...AND UNUSUALLY STRONG DEEP LAYER SHEAR FOR
AUGUST. HAVE ALREADY SEEN ONE THUNDERSTORM NEAR CENTER TX EARLIER
THIS MORNING WITH AN BRIEF BUT INTENSE MESOCYCLONE...SO SLIGHT
RISK FROM SPC SEEMS REASONABLE.

ALSO MADE MINOR ADJUSTMENTS TO POPS AND TEMPS FOR TONIGHT BUT REST
OF FORECAST IS ON TRACK.  UPDATE OUT SHORTLY.

SHAMBURGER

&&

.PREV DISCUSSION... /ISSUED 353 AM CDT TUE AUG 12 2008/

SYNOPSIS...
A STATIONARY FRONT EXTENDS FROM NORTHEAST TEXAS THROUGH NORTHERN
LOUISIANA TO ACROSS NORTHERN GEORGIA. PRESSURES WILL FALL ACROSS NORTHERN
LOUISIANA THIS MORNING...INDUCING A WAVE CYCLONE TO FORM AND THEN
MOVE EAST ALONG THE FRONTAL BOUNDARY.

THE CIRCULATION ASSOCIATED WITH THE DEEPENING WAVE CYCLONE WILL
PUSH A COLD FRONT THROUGH THE FORECAST AREA BY WEDNESDAY MORNING.
THIS UNUSUAL COLD FRONT WILL COME TO A HALT ACROSS THE COASTAL
WATERS BY WEDNESDAY EVENING.

FURTHER-UP...A WEST TEXAS DOME OF HIGH PRESSURE RIDGES SOUTHEAST
THROUGH SOUTH TEXAS AND INTO THE NORTHWEST GULF OF MEXICO.
SHORTWAVES EMANATING OUT OF THE COLORADO FRONT RANGE...ARE ROTATING
AROUND THE PERIPHERY OF THE DOME...PASSING THROUGH KANSAS...
ARKANSAS...AND LOUISIANA.

DISCUSSION...
PRESSURES WILL FALL ACROSS NORTHERN LOUISIANA...FORCING THE
SLANTWISE-ASCENDING BAY-OF-CAMPECHE AIR TO TURN MORE CYCLONICALLY
WHEN ENCOUNTERING THE LOUISIANA COAST...A TROWAL AIRSTREAM.

THE TROWAL AIRSTREAM IS USUALLY ASSOCIATED WITH ELONGATED RAINBANDS
THAT TEND TO PARALLEL THE FRONTAL SYSTEM. WITH MOISTURE AND
POTENTIAL INSTABILITY ALREADY IN PLACE...THE COUPLING OF FRONTAL
LIFT WITH MESO-SCALE LIFT ATTENDING THE PASSING SHORTWAVES WILL
MAKE FOR A HEAVY RAIN EVENT.

FOR TODAY...THE 12-HOUR BASIN-AVERAGED RAINFALL TOTALS WILL RANGE
FROM 1/2 TO 1 INCH...WITH MAXIMUM SPOT TOTALS RANGING FROM 2 TO 4
INCHES. IN GENERAL YOU CAN EXPECT WIDESPREAD RAIN WITH SCATTERED
THUNDERSTORMS EMBEDDED IN THE RAIN SHIELD. LOCAL FLOODING IS
POSSIBLE IN POOR DRAINAGE AREAS.

THE AFTERNOON TEMPERATURES WILL BE RUNNING ON THE COOL SIDE
..FROM 3 TO 5 DEGREES BELOW NORMAL...DUE TO EVAPORATIVE COOLING
AND CLOUD COVER.

FOR TONIGHT...THE RAINS WILL BE TAPERING OFF...WITH PASSAGE OF
THE COLD FRONT. THE DRY AIR INTRUSION WILL BE STRONGEST AT THE
MIDTROPOSPHERE.

MARINE...
THE TIDES WILL BE RUNNING ABOUT 1/2 FOOT ABOVE NORMAL DUE MODERATE
SOUTHERLY WINDS AND LONG PERIOD SOUTHERLY SWELLS OF AROUND 6 SECONDS.
THE HIGHEST TIDES ARE EXPECTED THIS MORNING.

 	SABINE PASS 2.0 FT.
	CALCASIEU PASS 3.0 FT.
	CYPERMORT POINT 2.8 FT.
	LAKE CHARLES CIVIC CENTER 1.6 FT.
	FRESH WATER CANAL LOCKS 2.4 FT.

AVIATION...
WIDESPREAD RAIN WITH EMBEDDED THUNDERSTORMS CAN BE EXPECTED
TODAY...TAPERING OFF THIS EVENING WITH PASSAGE OF A COLD FRONT.
IN GENERAL...MVFR CEILINGS CAN BE EXPECTED IN THE RAIN
SHIELD...LOWER IN HEAVY SHOWERS AND THUNDERSTORMS.

&&

.PRELIMINARY POINT TEMPS/POPS...
KLCH  88  75  93  73  94 /  70  40  40  20  10
KBPT  88  74  93  73  94 /  70  40  20  20  10
KAEX  85  71  93  70  94 / 100  40  10  10  10
KLFT  89  74  90  73  93 /  70  60  40  20  10

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE
     FOLLOWING ZONES: 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...
     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.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LAKE CHARLES LA
404 AM CDT TUE AUG 12 2008

GMZ450-452-455-470-472-475-LAZ027>033-041>045-051>055-TXZ180>182-
201-215-216-131115-
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-
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-VERNON-RAPIDES-AVOYELLES-BEAUREGARD-
ALLEN-EVANGELINE-ST. LANDRY-CALCASIEU-JEFFERSON DAVIS-ACADIA-
LAFAYETTE-UPPER ST. MARTIN-CAMERON-VERMILION-IBERIA-ST. MARY-
LOWER ST. MARTIN-TYLER-JASPER-NEWTON-HARDIN-JEFFERSON-ORANGE-
404 AM CDT TUE AUG 12 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF THE NORTHWEST
GULF OF MEXICO...CENTRAL LOUISIANA...SOUTH CENTRAL LOUISIANA...
SOUTHWEST LOUISIANA...WEST CENTRAL LOUISIANA AND SOUTHEAST TEXAS.

.DAY ONE...TODAY AND TONIGHT
WIDESPREAD RAIN WITH SCATTERED EMBEDDED THUNDERSTORMS ARE EXPECTED
FOR TODAY. THE 12-HOUR AREA-AVERAGED RAINFALL TOTALS WILL RANGE FROM
1/2 TO 1 INCH...WITH MAXIMUM SPOT TOTALS RANGING FROM 2 TO 4 INCHES.
LOCAL FLOODING IS POSSIBLE IN POOR DRAINAGE AREAS.

RAINS WILL TAPER OFF THIS EVENING WITH PASSAGE OF AN UNUSUAL
AUGUST COLD FRONT.

ALSO...A SMALL CRAFT ADVISORY IS IN EFFECT FOR TODAY DUE MODERATE
SOUTHERLY WINDS. THE TIDES WILL BE RUNNING ABOUT 1/2 FOOT ABOVE
NORMAL DUE TO LONG PERIOD SOUTHERLY SWELLS OF AROUND 6 SECONDS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED MAINLY AFTERNOON SHOWERS AND THUNDERSTORMS WILL RETURN ON
FRIDAY AND PERSIST INTO MONDAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL NOT BE NEEDED.