Tornado Warning 18, NWS Houston/Galveston, TX

SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
255 PM CDT FRI JUN 13 2003

UPDATE...
SPC IS ISSUING SEVERE THUNDERSTORM WATCH #534 FOR ALL BUT THE
COASTAL COUNTIES OF SE TX UNTIL 01Z. TSRA ARE EXPECTED TO INTENSIFY
ALONG OUTFLOW BOUNDARY FROM AUSTIN TO LIVINGSTON OVER THE NEXT FEW
HOURS WHILE ADDITIONAL ACTIVITY APPROACHES FROM THE WEST. CONVECTION
WILL SLOWLY PUSH SOUTH TOWARDS I-10 THROUGH EARLY EVENING. WILL BUMP
UP POPS MOST AREAS AS A RESULT.

DISCUSSION...
SERIES OF SHORTWAVES AND DEVELOPING UPPER TROF WILL KEEP HIGH RAIN
CHANCES IN THE FCST FOR THE NEXT SEVERAL DAYS.

PER SWOMCD...MAY SEE A FEW PULSE-TYPE SEVERE STORMS WITH ACTIVITY
AFFECTING FAR ERN COUNTIES NEXT COUPLE OF HOURS. OTHER TSRA HAVE
ERUPTED OVER EDWARDS PLATEAU AREA. THIS ACTIVITY MAY AFFECT WRN
PORTIONS OF CWA EARLY THIS EVENING BEFORE WEAKENING. MAIN FCST
CONCERN FOR TONIGHT WILL BE MCS PROGGED TO DEVELOP OVER NW TEXAS/LOW
ROLLING PLAINS...AND EVENTUALLY HEAD TOWARD CWA. MODELS HAVE PROGGED
THIS FEATURE FOR SEVERAL RUNS NOW. 12Z ETA/GFS CONTINUE TREND WITH
STRONG 300 MB DIFLUENCE DEVELOPING OVER ERN HALF OF TX BETWEEN
06Z-12Z TO HELP PROPAGATE MCS EASTWARD TOWARD AREA. DEVELOPING 30 KT
LLJ SHOULD KEEP ATMOSPHERE UNSTABLE TONIGHT AND HELP TO SUSTAIN
STRENGTH OF SYSTEM. WITH PROLIFERATION OF MCSS WILL KEEP HIGH POPS
ALL AREAS FOR TNGT. WILL MENTION SEVERE ALL ZONES WITH MAIN THREAT
BEING DAMAGING WINDS ASSOCIATED WITH LATE NIGHT MCS.

SHORTWAVE MOVING ACROSS SRN PLAINS TNGT WILL EVOLVE INTO UPPER TROF
THAT WILL EXTEND SOUTHWARD INTO CENTRAL/SE TX THROUGH EARLY NEXT
WEEK. ATMOSPHERE WILL BE UNCAPPED WITH PWS HOVERING AROUND 1.9 TO 2
INCHES. WILL LIKELY SEE SERIES OF CONVECTIVE SYSTEMS FORM AND ROTATE
AROUND UPPER LOW...WITH LOW LEVEL BOUNDARIES FOCUSING ACTIVITY OVER
CWA. EXPECT TO SEE PERIODS OF SHRA/TSRA WITH BREAKS OF A FEW HOURS
IN BETWEEN. WILL FCST 40/50 POPS ACROSS THE BOARD SATURDAY THROUGH
MONDAY. WIND FIELDS WEAKEN CONSIDERABLY DURING THE WEEKEND SO WX
THREAT WILL SHIFT TO MORE OF A HEAVY RAINFALL THREAT. LATEST GFS
BRINGS DRIER AIR INTO NRN ZONES MON/TUE BUT WILL DELAY DRYING THINGS
OUT UNTIL WEDNESDAY.

MARINE...WILL KEEP SCEC GOING ALL WATERS FOR TONIGHT. LLJ WEAKENS
AND PRESSURE GRADIENT SLACKENS STARTING SATURDAY SO WINDS WILL
FINALLY SUBSIDE A LITTLE AFTER TONIGHT.

35/42

.HGX...SEVERE THUNDERSTORM WATCH INLAND COUNTIES UNTIL 01Z.
       SCEC 00-60 NM BAYS AND WATERS.

.PRELIMS...
CLL TT 070/091 070/087 068 854
IAH TT 074/092 073/089 071 654
GLS TT 081/088 078/087 077 553

GMZ330-335-TXZ163-164-176>179-195>200-210>214-226-227-235>238-
141200-

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1135 AM CDT FRI JUN 13 2003

...SLIGHT RISK OF SEVERE THUNDERSTORMS OVER SOUTHEAST TEXAS THIS
AFTERNOON AND TONIGHT...
...HEAT INDICES OF 105 TO 110 DEGREES POSSIBLE THIS AFTERNOON...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST TEXAS.

.DAY ONE...TODAY AND TONIGHT.
A SERIES OF WEAK OUTFLOW BOUNDARIES WILL COMBINE WITH A HOT AND
HUMID AIRMASS OVER SOUTHEAST TEXAS TO PRODUCE SCATTERED SHOWERS AND
THUNDERSTORMS GENERALLY EAST OF A LINE FROM COLLEGE STATION TO
HOUSTON THIS AFTERNOON. A FEW STORMS COULD BECOME SEVERE PRODUCING
HAIL OR DOWNBURST WINDS.

TEMPERATURES IN THE MID 90S AND HIGH HUMIDITIES WILL COMBINE TO
PRODUCE HEAT INDICES OF AT LEAST 103 TO 108 DEGREES THIS
AFTERNOON...MAINLY OVER HOUSTON/GALVESTON AND SURROUNDING AREAS.
HEAT INDICES COULD PEAK AS HIGH AS 110 DEGREES IN SOME LOCATIONS.
PERSONS WHO MUST BE OUTSIDE THIS AFTERNOON SHOULD DRINK PLENTY OF
WATER AND LIMIT YOUR EXPOSURE TO THE SUN. TAKE FREQUENT BREAKS IN
AIR-CONDITIONING.

TONIGHT...A COMPLEX OF SEVERE THUNDERSTORMS IS EXPECTED TO DEVELOP
OVER THE BIG COUNTRY AND EDWARDS PLATEAU AND MOVE SOUTHEAST INTO THE
AREA BETWEEN 10 PM AND 4 AM SATURDAY MORNING. THE MAIN THREATS WILL
BE DAMAGING WINDS AND POSSIBLY BRIEF TORNADOES...ALONG WITH LOCALLY
HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

A SLOW MOVING UPPER LEVEL LOW PRESSURE SYSTEM WILL SAG SOUTH INTO
NORTH TEXAS AND LEAD TO AN EXTENDED PERIOD OF SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS SOUTHEAST TEXAS. THOUGH THE MUCH NEEDED
RAINFALL WILL BE WELCOME THE SLOW MOVING SYSTEM MAY LEAD TO AN
INCREASED HEAVY RAINFALL THREAT MONDAY THROUGH WEDNESDAY. IN
ADDITION ISOLATED SEVERE THUNDERSTORMS ACCOMPANY THE SYSTEM.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS POSSIBLE LATER TONIGHT.

TXZ163-164-176>179-195>200-210>213-226-227-140100-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
304 PM CDT FRI JUN 13 2003

...SEVERE THUNDERSTORM WATCH ISSUED FOR MUCH OF SOUTHEAST TEXAS UNTIL
800 PM CDT...

A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED FOR THE FOLLOWING
COUNTIES OF SOUTHEAST TEXAS...

AUSTIN...BRAZOS...BURLESON...COLORADO...FORT BEND...GRIMES...
HARRIS...HOUSTON...LIBERTY...MADISON...MONTGOMERY...POLK...SAN
JACINTO...TRINITY...WALKER...WALLER...WHARTON AND WASHINGTON
COUNTIES

...UNTIL 800 PM CDT.

THE COASTAL COUNTIES...BRAZORIA...CHAMBERS...GALVESTON...JACKSON AND
MATAGORDA...ARE NOT IN THE SEVERE THUNDERSTORM WATCH.

SHOWERS AND THUNDERSTORMS CONTINUE TO DEVELOP ACROSS CENTRAL AND
SOUTHEAST TEXAS. ACTIVITY TO OUR WEST IS EXPECTED TO STRENGTHEN AS IT
MOVES TO THE EAST INTO SOUTHEAST TEXAS. DAMAGING WINDS AND LARGE
HAIL ARE THE PRIMARY THREAT WITH THESE THUNDERSTORMS.

STAY TUNED TO NOAA WEATHER RADIO OR OTHER WEATHER NEWS SOURCES FOR
FURTHER UPDATES ON THIS SEVERE WEATHER THREAT.