Severe Thunderstorm Warning 109, NWS Houston/Galveston, TX

SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
210 PM CDT THU SEP 19 2002

BANDS OF SHOWERS AND THUNDERSTORMS CONTINUING OVER CWFA AND
PRONOUNCED BAND FROM WESTERN HARRIS TO NORTHERN LIBERTY COUNTIES
PRODUCING ABOUT AN INCH PER HOUR EARLY THIS AFTERNOON. FRONTAL BOUNDARY
EXTENDING FROM BETWEEN ARD AND SPS BETWEEN BWD AND SJ. PRE-FRONTAL
TROUGH BETWEEN DRT AND LRD NORTH TO THE HILL COUNTRY. UNSTABLE AIR
MASS WITH HIGH PW VALUES ABOUT 2 INCHES AND PASSING WEAK UPPER LEVEL
IMPULSE WILL CONTINUE TO PRODUCE SCATTERED SHRA/TSRA OVER REGION.
FRONTAL BOUNDARY EXPECTED TO PRODUCE SQUALL LINE TYPE SCENARIO
COMING FROM THE W/NW LATER THIS EVENING AND MOVING ACROSS CWFA
OVERNIGHT. IT APPEARS THAT FRONT SHOULD MOVE ACROSS IAH AROUND 4 AM
TOMORROW...AND SHOULD BE NEAR THE COAST AROUND 6 AM. BEST UPPER
LEVEL SUPPORT WILL BE OVER NORTHERN ZONES WHICH IS CLOSER TO
ENTRANCE REGION OF UPPER LEVEL JET. THIS IS WHERE WE EXPECT BETTER
CHANCES FOR SEVERE WEATHER. WE WILL CONTINUE W/SLIGHT CHANCE SEVERE
FOR ALL ZONES TONIGHT (SEE SWODY1) ALONG W/POSSIBLE LOCALLY HEAVY
RAINFALL. WE WILL LOWER SCA TO CAUTION FOR COASTAL WATERS AS
SOMEWHAT FLATTER PRESSURE GRADIENT IS INDICATED BY MODELS AND
CURRENT TRENDS INDICATE SAME. AFTER FROPA...OFFSHORE FLOW WILL
CONTINUE FOR THE NEXT SEVERAL DAYS. SECONDARY COLD FRONT SHOULD
APPROACH OUR REGION LATE SUNDAY REINFORCING DRY NORTHERLY FLOW IN
PLACE. SWELLS FROM ISIDORE SHOULD BE AFFECTING COASTAL WATERS MAINLY
OFFSHORE REGION BY SUNDAY. AT LEAST FOR NOW...WEEKEND LOOKS GREAT
W/PWATS UNDER AN INCH...AND THIS SCENARIO MAY LAST FOR SEVERAL MORE
DAYS THEREAFTER.

PLEASE SEE TCDAT5 FOR TPC DISCUSSION ON ISIDORE.

.HGX...SCEC 0 TO 60 NM COASTAL WATERS.

CLL BU 067/086 060/086 062 710
IAH BU 070/086 061/087 062 630
GLS TU 076/085 072/085 072 650

37/35

TXZ163-164-176>179-195>200-210>214-226-227-235>238-200900-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
330 PM CDT THU SEP 19 2002

...SEVERE THUNDERSTORMS AND LOCALLY HEAVY RAINFALL POSSIBLE
THROUGH TONIGHT...

A MOIST AND UNSTABLE AIRMASS IN PLACE OVER SOUTHEAST TEXAS...AND A
PASSING UPPER LEVEL DISTURBANCE WILL RESULT IN THE CONTINUING
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS OVER THE REGION. A COLD FRONT
WILL APPROACH THE REGION FROM THE WEST. THE FRONT IS EXPECTED TO
ENTER THE WESTERN PORTIONS OF SOUTHEAST TEXAS DURING THE LATE EVENING
HOURS AND REACH THE COAST DURING THE EARLY MORNING HOURS ON FRIDAY.
AHEAD OF THE FRONT...SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP AND MOVE NORTHWARD. A LINE OF THUNDERSTORMS IS EXPECTED
TO DEVELOP NEAR AND ALONG THE FRONT. AS THIS LINE OF THUNDERSTORMS
MOVES ACROSS SOUTHEAST TEXAS TONIGHT...THERE WILL BE A THREAT OF LARGE
HAIL AND STRONG DAMAGING WINDS.

RAINFALL AMOUNTS OF 1 TO 2 INCHES CAN BE EXPECTED OVER MUCH OF
THE AREA THROUGH TONIGHT AS UPPER LEVEL DISTURBANCES AND
THE FRONTAL BOUNDARY INTERACT WITH TROPICAL MOISTURE OVER SOUTHEAST
TEXAS. LOCALIZED RAINFALL AMOUNTS OF 3 TO 5 INCHES ARE POSSIBLE.

STAY TUNED TO NOAA WEATHER RADIO OR OTHER WEATHER NEWS SOURCES FOR
LATER STATEMENTS CONCERNING THIS SEVERE WEATHER AND HEAVY RAIN THREAT.