Flash Flood Warning 8, NWS Houston/Galveston, TX

SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1000 AM CDT SUN JUL 14 2002

CONVECTION INCREASING ACROSS NW ZONES THIS MORNING THANKS TO UVV
FROM SHORTWAVE WHICH IS NOW MOVING ACROSS NE TX. 12Z 850/700 MB
ANALYSIS SHOWS SLIGHTLY LESS MOISTURE OVER CWA THAN YESTERDAY WITH
DEWPOINTS RUNNING 2-3 C LOWER. HOWEVER DYNAMIC FORCING APPEARS MORE
FAVORABLE FOR CONVECTION TODAY. ANALYZED 50-60 KT JET STREAK OVER NE
TX/NRN LOUISIANA WITH CWA LIKELY TO REMAIN IN RRQ OF JET THROUGH
TONIGHT. FCST MODEL SOUNDINGS DEPICT UNCAPPED ATMOSPHERE WITH
CONVECTIVE TEMPS IN THE MID 80S AND PWS HOVERING AROUND 2-2.1
INCHES. DEVELOPING MESOSCALE BOUNDARIES/OUTFLOWS WILL FOCUS AREAS OF
HEAVIEST RAINFALL...WITH PRIMARY CONVERGENT AREA LIKELY TO BE NW-SE
ACROSS THE CENTRAL ZONES.

WILL KEEP FFA GOING FOR ENTIRE CWA AS IT WILL ONLY TAKE 2-3 INCHES
IN THE AREAS THAT WERE HIT HARD YESTERDAY TO PRODUCE FLASH FLOODING.
WILL LOWER SW ZONES TO 50 POPS WITH SLIGHTLY DRIER AIR IN PLACE.
TEMPS RUNNING MUCH COOLER THAN YESTERDAY AND WITH EXPECTED CLOUD
COVER/PRECIP WILL LOWER INLAND SECTIONS SEVERAL DEGREES.

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.HGX...FFA ALL ZONES THROUGH TONIGHT.

PRELIMS...
CLL TT 086/073 090/073 092 766
IAH TT 087/073 090/073 092 766
GLS TT 088/078 087/078 088 766 SW ZONES 566

PREVIOUS DISCUSSION...
ATMOS HAS STABILIZED IN THE WAKE OF THE WIDESPREAD
CONVECTION DURING THE EVENING HOURS OVER SE TX. RECEIVED VERY
IMPRESSIVE RAINFALL RATES IN TROPICAL AIRMASS WHICH LED TO FLASH
FLOODING IN WHARTON COUNTY AND URBAN STREET FLOODING IN HARRIS
COUNTY.

MAIN ISSUE FOR THE UPCOMING PACKAGE IS HEAVY RAIN/FLOODING THREAT.
OVERALL SYNOPTIC SITUATION CHANGES LITTLE TODAY AND TONIGHT AND FOR
THAT REASON WILL FORECAST LIKELY POPS ALL AREAS TODAY. MESOSCALE
BOUNDARIES WILL DICTATE WHO RECEIVES THE MOST RAINFALL TODAY AND
TONIGHT. WILL THEREFORE NOT TRY TO SELECT ANY FAVORED AREAS WHEN PW
VALES ARE A LITTLE OVER 2 INCHES AREAWIDE. SHORT WAVE ENERGY WILL
CONTINUE TO ROTATE AROUND THE UPPER LOW AND MOVE ACROSS FA THROUGH
MONDAY. SO ONCE ATMOSPHERE RECOVERS...SHWRS AND TSTMS SHOULD
BEGIN TO DEVELOP OVER THE AREA. BELIEVE SCT SHWRS AND TSTMS WILL
DEVELOP SOMETIME THIS MORNING AND COVERAGE WILL INCREASE DURING THE
AFT/EVE HOURS. BELIEVE FLASH FLOOD WATCH IS A GOOD IDEA. HOWEVER...I
HAVE DECIDED TO INCLUDE ALL ZONES DUE TO THE POTENTIAL OF VERY HIGH
HOURLY RAINFALL RATES (4 INCHES/HR) AND THE POSSIBILITY OF
BACKBUILDING AND TRAINING AGAIN IN DIFFLUENT UPPER LEVEL FLOW.

TUE-FRI PERIOD OF THE FORECAST DOES NOT LOOK MUCH
DIFFERENT...ALTHOUGH I QUESTION HOW FAST TROPICAL MOISTURE WILL
ACTUALLY SHIFT NW OF REGION AS AVN IS ADVERTISING AND HAVE RAISED
TUES POPS ESPECIALLY FOR WESTERN ZONES. TEMPS ARE EXPECTED TO WARM
BACK INTO THE MID 90S ON WED.

THANKS LCH FOR COORD.

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