Flash Flood Warning 2, NWS Houston/Galveston, TX

SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
948 AM CST THU FEB 20 2003

QUASI STATIONARY FRONT DRAPED OVER THE SOUTHERN FA FROM NEAR BPT TO
PSX. WIDESPREAD RAINFALL OCCURRING OVER THE NORTHERN FA WHERE LOW TO
MID LEVEL CONVERGENCE FOCUSING THE ISENTROPIC LIFT. HAVE ALREADY
ISSUED URBAN AND SMALL STREAM ADVISORIES FOR THE NORTHERN COUNTIES.
WILL LIKELY ISSUING FLOOD WARNINGS FOR THESE COUNTIES LATER THIS
MORNING AS THE DEEP CONVECTION MOVES IN FROM THE WEST. WILL GO AHEAD
AND ADD MENTION OF SEVERE TO ZONES FOR THIS AFTERNOON THOUGH THE
THREAT IS MARGINAL AND SHOULD BE MAINLY OVER THE WESTERN AND
NORTHERN ZONES IN THE FORM OF HAIL. STORMS NEAR THE SFC BOUNDARY MAY
HAVE SOME POTENTIAL FOR DEEP MESOCYCLONES BUT EXPECTING THAT THE
RISK WILL BE HIGHER TONIGHT. OTHERWISE NO BIG CHANGES.  WILL PROBABLY
EXPAND THE FLASH FLOOD WATCH SOUTH IN THE AFTERNOON PACKAGE.

45/41/31/30

.HGX...FFA THROUGH TONIGHT FOR NORTHERN HALF OF SE TX.
       SCA HIGH ISLAND TO MATAGORDA OUT 20 TO 60 NM.

PRELIMS...
CLL TT 062/056 064/048 067 ++8
IAH TT 066/059 068/050 068 888
GLS TT 066/060 068/054 067 788

PREV DISC
COLD FRONT EXTENDS FROM JUST SOUTH OF VCT TO JUST NORTH OF IAH AT
08Z. FRONT MAY PUSH A LITTLE FARTHER SOUTH BEFORE STALLING.
ISENTROPIC LIFT PATTERN HAS SET UP NORTH OF FRONT WITH AREAS OF RAIN
AND ELEVATED TSRA AFFECTING NRN ZONES.

GENERALLY FOLLOWED 00Z ETA RUN FOR HANDLING OF UPPER LEVEL/SFC
FEATURES...BUT GFS HAS BETTER HANDLE ON DEPTH OF MOISTURE.
ISENTROPIC LIFT PATTERN WILL CONTINUE OVER NRN ZONES UNTIL FRONT
WASHES OUT LATER TODAY. 850 MB WAA PATTERN WILL DEVELOP OVER CWA
TRANSPORTING EVEN DEEPER MOISTURE (PWS 1.5-1.6 IN) OVER SE TX THIS
AFTN. ANOTHER DISTURBANCE WILL ARRIVE BY AROUND 18Z ENHANCING LIFT.
COMBINATION OF LIFT/WAA SHOULD LEAD TO WIDESPREAD CONVECTION OVER SE
TX THIS AFTN. WILL ISSUE FFA FOR NRN HALF OF CWA WHERE HEAVY RAIN (1
TO 2 INCHES) HAS FALLEN OVERNIGHT. WILL MENTION HEAVY RAIN THREAT
SOUTHERN HALF TODAY BUT HOLD OFF ON FFA TO SEE HOW SITUATION
EVOLVES. A FEW ELEVATED STORMS WITH HAIL ARE POSSIBLE TODAY BUT LACK
OF INSTABILITY SHOULD PRECLUDE SIGNIFICANT SEVERE THREAT.

UPPER LOW OVER SOUTHERN CA WILL SHIFT EASTWARD INTO SOUTH TX FRI.
LIFT WILL REMAIN ENHANCED TNGT/FRI AS VERY STRONG 300 MB DIFLUENCE
DEVELOPS OVER CWA AND SERIES OF WEAK SHORTWAVES MOVE ACROSS AHEAD OF
MAIN UPPER LOW. 40 TO 50 KT LLJ WILL CONTINUE TO TRANSPORT DEEP
MOISTURE INTO SE TX. ALTHOUGH INSTABILITY WILL BE LIMITED
SOMEWHAT...BACKED SFC WINDS WILL FAVOR POSSIBILITY OF ROTATING
STORMS WITH LOW WBZ POINTING TOWARD THREAT FOR HAIL. WILL MENTION
SVR/HVY RAIN TNGT/FRI. SQUALL LINE WILL LIKELY DEVELOP ALONG FRONT
FRI AFTN AND SWEEP ACROSS AT LEAST SRN HALF OF CWA. SOME WRAP-AROUND
PRECIP WILL OCCUR FRI NIGHT AS UPPER LOW MOVES ACROSS. SFC HIGH WILL
SETTLE OVERHEAD SATURDAY FINALLY DRYING THINGS OUT.

FOR LATER PERIODS...GFS STILL REMAINS OUTLIER WITH POLAR AIRMASS
SETTLING OVER AREA MON-WED. OTHER MODELS CONTINUE TO SHOW LONGWAVE
TROF DEVELOPING ACROSS ROCKIES WITH COLD AIR SHUNTED EAST OF AREA.

COORD WITH EWX AND CRP.

TXZ163-164-176>179-195>200-210>214-226-227-235>238-211300-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
700 AM CST THU FEB 20 2003

...THREAT FOR HEAVY RAINFALL AND SEVERE STORMS ACROSS SOUTHEAST TEXAS
THROUGH FRIDAY...
...FLOOD WATCH IN EFFECT THROUGH TONIGHT ALONG AND NORTH OF A BRENHAM
TO NEW WAVERLY TO SHEPHERD LINE...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST TEXAS.

.DAY ONE...TODAY AND TONIGHT

A STATIONARY FRONT WILL COMBINE WITH DEEP MOISTURE AND A SERIES OF
UPPER LEVEL DISTURBANCES TO PRODUCE NUMEROUS SHOWERS AND
THUNDERSTORMS ACROSS SOUTHEAST TEXAS. LOCALLY HEAVY RAINFALL
WILL BE POSSIBLE WITH SOME OF THE STORMS. RAINFALL AMOUNTS WILL
AVERAGE 2 TO 3 INCHES WITH ISOLATED TOTALS OF 5 INCHES WITH EVEN SOME
HEAVIER TOTALS POSSIBLE THROUGH TONIGHT. GIVEN THE HEAVY RAIN THAT
HAS FALLEN OVERNIGHT OVER THE NORTHERN HALF OF SOUTHEAST TEXAS...
RAINFALL OF THIS MAGNITUDE WILL CAUSE FLOODING.

IN ADDITION...THE ATMOSPHERIC WIND PROFILE WILL FAVOR THE POSSIBILITY
OF A FEW STORMS BECOMING SEVERE BY TONIGHT. LARGE HAIL AND ISOLATED
TORNADOES WILL BE THE PRIMARY SEVERE WEATHER THREATS...WITH DAMAGING
WINDS ALSO POSSIBLE.

REMEMBER...A FLOOD WATCH MEANS RAPIDLY RISING WATER OR FLOODING IS
POSSIBLE WITHIN THE WATCH AREA. CHECK OVER YOUR PREPAREDNESS
REQUIREMENTS...KEEP INFORMED...AND BE READY FOR QUICK ACTION IF
FLOODING IS OBSERVED OR IF A WARNING IS ISSUED.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

FRIDAY...A STRONG UPPER LEVEL STORM SYSTEM WILL MOVE ACROSS SOUTHEAST
TEXAS...WITH ADDITIONAL PERIODS OF SHOWERS AND THUNDERSTORMS EXPECTED.
LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH SOME OF THE STORMS...
WHICH COULD CREATE OR ENHANCE ONGOING FLOODING PROBLEMS. ALSO...A FEW
STORMS MAY BECOME SEVERE WITH LARGE HAIL...DAMAGING WINDS...OR
ISOLATED TORNADOES. RAINFALL WILL BEGIN TO TAPER OFF FRIDAY NIGHT AND
END BY SATURDAY MORNING.

SATURDAY THROUGH WEDNESDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS
TIME...BUT RIVER FLOODING PROBLEMS COULD BE ONGOING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TODAY AND TONIGHT.