Flash Flood Warning 54, NWS Houston/Galveston, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
952 AM CDT WED JUN 30 2004

.DISCUSSION...
BASED ON CURRENT RADAR LOOPS...SATELLITE PICTURES...INCOMING MODEL
DATA AND RECENT RAINFALL HISTORY...WILL REISSUE THE FLOOD WATCH AND
HAVE IT IN EFFECT FOR ALL OF SOUTHEAST TEXAS THROUGH THIS EVENING.
SHOWERS AND THUNDERSTORMS ARE BEGINNING TO BECOME MORE NUMEROUS
SOUTHWEST THROUGH WEST OF THE HOUSTON AREA AS A SHORTWAVE SLOWLY
MOVES ACROSS THE AREA. EXPECT THIS ACTIVITY TO GRADUALLY BUILD TO
THE NORTH AND THE NORTHEAST AS THE DAY PROGRESSES. LOCALLY HEAVY
RAINFALL WILL CONTINUE TO BE MENTIONED WITH THE CURRENT THOUGHT THAT
WIDESPREAD 1 TO 3 INCH RAINFALL AMOUNTS WILL BE POSSIBLE THROUGH
THIS EVENING. VERY ISOLATED LOCATIONS COULD RECEIVE 5 TO 7 INCHES.
WEATHER PARAMETERS FAVORING HEAVY RAINFALL INCLUDE PRECIPITABLE
WATER VALUES STILL ABOVE TWO INCHES...A DEVELOPING DIFLUENT FLOW
ALOFT AND A DEEP MOISTURE PLUME EXTENDING TO THE SOUTH SOUTHWEST
ACROSS MEXICO AND INTO THE EASTERN PACIFIC OCEAN.

THERE ARE A NUMBER OF SOUTHEAST TEXAS RIVERS NEAR OR ABOVE FLOOD
STAGE THIS MORNING...AND RAINFALL AMOUNTS OF TWO INCHES OR MORE
TODAY ARE ONLY GOING TO CAUSE THESE RIVERS TO RISE EVEN MORE.

IAH NEEDS 1.06 INCHES OF RAIN TODAY MAKE JUNE 2004 THE WETTEST JUNE
ON RECORD. IF IAH CAN GET JUST UNDER 3 INCHES OF RAIN BY MIDNIGHT...
WE WILL SURPASS THE AVERAGE ANNUAL RAINFALL.  42/35/47/99
&&

.HGX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FOR ALL OF SOUTHEAST TEXAS THROUGH THIS EVENING.
&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 86 73 91 73 92 / 70 40 40 20 20
HOUSTON(IAH)          87 74 91 74 91 / 70 40 40 20 20
GALVESTON (GLS)       86 80 88 79 88 / 70 30 30 20 20
&&

.PREVIOUS DISCUSSION (303 AM CDT)...
SE TX WAS UNDER A DIFFLUENT FLOW AT 200 AND 300 MB WITH THE RIDGE AXIS
JUST TO THE WEST.  IN THE LOW AND MID LEVELS AN ABUNDANCE OF MOISTURE
WAS AVAILABLE AND POPS AND RAINFALL ARE THE MAIN FORECAST PROBLEMS OF
THE DAY.  A BLEND OF THE ETA AND GFS LOOKED TO BE THE BEST FOR MODEL
GUIDANCE...THE ETA LOOKED GOOD ON THE MID AND UPPER FEATURES AND THE
GFS ACTUALLY VERIFIED ON PW/S.

700 MB DEWPOINTS OF 4 TO 6 SHOULD MOVE INTO THE SOUTHERN HALF OF THE
FORECAST AREA TODAY.  PW/S OF NEAR 2 INCHES ARE EXPECTED EARLY...THEN
CLIMB INTO THE 2.1 TO 2.3 INCH RANGE BY THIS AFTERNOON.  WITH FLASH
FLOOD GUIDANCE NUMBERS ON THE LOW SIDE AND WITH RAINFALL AMOUNTS OF 1
TO 3 INCHES (AND ISOLATED HIGHER AMOUNTS IN THE SOUTH)...WILL ISSUE A
FLOOD WATCH THROUGH 6 PM FOR AREAS SOUTH OF INTERSTATE 10.

A DRYING TREND CONTINUES TO BE THEN EXHIBITED BY THE MODELS.  LESS
COVERAGE IS EXPECTED TOMORROW AS BOTH THE ETA AND GFS BRING A
SHORTWAVE TROUGH ACROSS THE AREA BUT WITH A DRIER AIRMASS OVERHEAD.
THEN...A PATTERN CHANGE SHOULD OCCUR BY THE END OF THIS WEEK.  WILL GO
WITH MAINLY ISOLATED POPS AFTER FRIDAY.  THE GFS CONTINUES TO FORECAST
A WEAKNESS IN THE RIDGE OVER THE GULF NEXT WEEK...BUT KEEPS SE TX ON
THE DRY SIDE AT THE END OF THE FORECAST PERIOD.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1015 AM CDT WED JUN 30 2004

TXZ163-164-176>179-195>200-210>214-226-227-235>238-011200-
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-GALVESTON-
GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA-MONTGOMERY-
POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON-WHARTON-
1015 AM CDT WED JUN 30 2004

...FLOOD WATCH THROUGH MIDNIGHT TONIGHT FOR ALL OF SOUTHEAST TEXAS...

.DAY ONE...TODAY AND TONIGHT.
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL DEVELOP TODAY
ACROSS SOUTHEAST TEXAS. GENERAL RAINFALL AMOUNTS OF 1 TO 3 INCHES CAN
BE EXPECTED THROUGH THIS EVENING. ISOLATED TOTALS OF 5 TO 7 INCHES ARE
POSSIBLE. BECAUSE OF THE NEARLY SATURATED GROUND...ANY HEAVY RAINFALL
WILL WILL LIKELY CAUSE FLOOD PROBLEMS IN THE WATCH AREA. ALSO...RIVER
FLOODING IS ONGOING ACROSS PORTIONS OF SOUTHEAST TEXAS...AND ANY
SIGNIFICANT ADDITIONAL RAINFALL WILL LIKELY LEAD TO MORE RISES ON
THESE RIVERS.

IN ADDITIONAL TO THE HEAVY RAINFALL THREAT...CONDITIONS ARE ALSO
FAVORABLE FOR THE FORMATION OF FUNNEL CLOUDS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.
SCATTERED THUNDERSTORMS ON THURSDAY MAY GENERATE ISOLATED FLOODING.
ALSO...THE RIVER FLOODING SITUATION WILL CONTINUE TO BE MONITORED.
OTHERWISE...NO HAZARDOUS WEATHER IS EXPECTED THROUGH THE PERIOD.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE NEEDED TODAY AND THIS EVENING.