Severe Thunderstorm Warning 97, NWS Lake Charles, LA

SOUTHEAST TEXAS AND SOUTHWEST LOUISIANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
925 PM CDT FRI APR 7 2000

LAKE CHARLES 7 PM UPPER AIR SOUNDING DISPLAYS A THICK WARM DRY LAYER
AT BASED AT 5000 FEET ABOVE SURFACE. THIS...ABOVE A RELATIVELY
SHALLOW MORE MOIST LAYER. THESE STABLE THERMODYNAMIC CONDITIONS WILL
LIKELY INHIBIT STORM PRODUCTION TONIGHT ESPECIALLY OVER THE SOUTHERN
PART OF THE FORECAST AREA. EXPECT THE LINE OF THUNDERSTORMS MOVING
TOWARD THE LOCAL AREA WILL DIMINISH IN COVERAGE DUE TO LOSS OF DAY
TIME HEATING AND MOVEMENT INTO THE MORE STABLE AIRMASS OVER SOUTHERN
LOUISIANA INTO SOUTHEAST TEXAS. SCATTERED SHOWERS / THUNDERSTORMS
WILL PROBABLY MAKE IT INTO NORTHERN PARTS OF THE AREA WHERE THE
PREVIOUS FORECAST CALLED FOR A 30 PERCENT CHANCE OF RAIN.

WILL INCREASE THE CHANCE OF RAIN NORTHWEST PART OF THE AREA WHERE
STRONG STORMS ARE APPROACHING AT THIS TIME. MESO-ETA IS INDICATING
THAT REASONABLY STRONG LOW LEVEL CONVERGENCE IN THAT AREA WHERE CAP
IS PROBABLY WEAKER COULD INDUCE UPWARD MOTION THROUGH THE WARM LAYER
/ CAP. WILL UPDATE FORECAST TO INCREASE POPS BY 20 PERCENT NORTHWEST
PART OF AREA AND 10 PERCENT ACROSS CENTRAL LOUISIANA. EXPECT
PRECIPITATION TO DIMINISH LATER TONIGHT AS SYSTEM MOVES INTO MORE
STABLE AIR OVER THE SOUTH PART OF THE FORECAST AREA SO WILL NOT
CHANGE POPS SOUTH.

20 / SPARKS

.LCH...NPW (WIND ADVISORY) ALL ZONES
       SCA FROM HIGH ISLAND TO ATCHAFALAYA RIVER OUT 60 NM
.LA...NPW LAZ027>033-041>045-051>055...SCA GMZ450-455-470-475
.TX...NPW TXZ180>182-201-215-216...SCA GMZ450-470

PREVIOUS DISCUSSION...

LATEST SFC ANALYSIS SHOWS STRONG COLD FRONT ACROSS NC TX...E OK...
AND NW AR NEAR MWL...ADM...MLC AND FSM.  MOVING ALONG QUICKLY AS
FRONT WAS IN W OK/C KS AT THE START OF MY SHIFT NEAR 13Z. VIS SAT
SHOWS CLOUD FIELD GOING SCT...WITH AREAS NEAR LFT STILL REPORTING
BKN045-050 AT THE MOMENT.

COLD FRONT WILL CONTINUE TO BARREL ITS WAY THRU THE AREA TONIGHT.
STRONG N WINDS OF 25 TO 30 MPH AND GUSTS TO 40 MPH WILL REACH INLAND
SE TX BY 06Z SAT (1AM)...AND COMPLETELY THRU CWA INCLUDING COASTAL
WATERS BY 12Z.  A WIND ADVISORY WILL BE ISSUED INCLUDING THIS
WORDING FOR BOATERS...LAWN FURNITURE...PETS...TRASHCANS...YOU NAME
IT. PER TCP CONFERENCE CALL FOR MARINE ZONES...WILL WORD 25-30 KT
GUSTS TO GALE IN A SPLIT ZONE CONFIGURATION FOR TONIGHT HIGH
ISLAND TO CAMERON...AND TOMORROW FOR ENTIRE AREA...MAINLY A TIMING OF
THE FRONT AND STRONG GRADIENT WINDS BEHIND IT. BY SAT AFTERNOON...
THE WINDS WILL EASE A BIT 15 TO 20 MPH ACROSS INLAND ZONES...BUT
WILL KEEP WORDING ENTIRE PERIOD FOR S ZONES.  HIGH WILL SETTLE OVER
CENTRAL LA BY 12Z SUN...ALLOWING FOR EXCELLENT RADIATIONAL COOLING
AS THE WINDS BECOME LIGHT AND VARIABLE.

NOW FOR PRECIPITATION WITH THE FRONT.  SPC PLACED TAIL END OF
SLIGHT RISK INTO EXTREME N PART OF AREA INCLUDING N TYLER...JASPER...
NEWTON...VERNON...RAPIDES...AND AVOYELLES.  MOST OF THE ENERGY WILL
BE TO THE N AND E AS THE MID/UPPER LEVEL TROF DEEPENS AS IT PASSES
TO OUR EAST.  MESOETA DEEP MOISTURE PROFILES ONLY SHOW SUFFICIENT RH
UP TO 700MB OVER C LA AT THE TIME OF FROPA...WITH THE ETA...NGM...AND
AVN SHOWING EVEN LESS FAVORABLE PROFILES.  ALSO LESS FAVORABLE
MOISTURE DEPTH S ZONES. THIS FRONT WILL GENERATE SUFFICIENT
LIFT AND UPPER DIVERGENCE AS IT MOVES THRU TO GENERATE SCT (30%)
INLAND ZONES...WITH THE POSSIBILITY THAT ONE OF THESE THUNDERSTORMS
MAY BE SEVERE IN THE FORM OF BRIEF DOWNBURSTS AND OR HAIL.  BELIEVE
20% WILL BE SUFFICIENT FOR S ZONES...WITHOUT SVR MENTION.  PRECIP
FREE FOR REST OF WEEKEND.

TEMPS IN THE 60S PRIOR TO FROPA WILL RAPIDLY DROP TO 50-55 RANGE BY
SUNRISE...AND ONLY STRUGGLE IN THE 60-63 RANGE SAT.  SAT NIGHT/SUN
LOOKS TO BE CLOSE TO...IF NOT RECORD BREAKING COLD FOR CENTRAL LA
FOR THIS TIME OF YEAR. RECORDS SUNDAY MORNING ARE:

ALEXANDRIA, LA    38 IN 1972  RECORDS SINCE 1930
BEAUMONT, TX      38 IN 1973  RECORDS SINCE 1901
LAKE CHARLES, LA  35 IN 1916  RECORDS SINCE 1893
LAFAYETTE, LA     35 IN 1916  RECORDS SINCE 1893

AS THE HIGH MOVES EAST...A RETURN FLOW WILL SET UP FOR LATE SUNDAY
AFTERNOON. TUE AND WED LOOKS LIKE THE NEXT CHANCE FOR RAIN.

8

PREVIOUS NUMBERS...
AEX 50/61/37/66 3000
BPT 53/61/40/65 2000
LCH 54/62/40/65 2000
LFT 55/62/40/64 2000