Flash Flood Warning 57, NWS Houston/Galveston, TX

SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
838 PM CST MON OCT 28 2002

VERY HEAVY RAINFALL OCCURRING FROM WHARTON COUNTY INTO THE HOUSTON
METROPLEX. 2.72 OBSERVED IN 1 HOUR AT SPRING BRANCH AND BINGLE. ONE
STORM OVER HARRIS COUNTY LOOKING TORNADIC. LOCAL VWP INDICATING
HELICITY 150-180 IN THE LOWEST 2KFT. TORNADO WATCH IN EFFECT NOW AS
WELL AND WILL BE UPDATING ZONES SHORTLY. WARM FRONT SOMEWHERE
NEAR A HALLETTSVILLE TO HOUSTON TO NORTH OF BEAUMONT LINE. AND
STILL MOVING NORTH. COLD FRONT MAKING PROGRESS EASTWARD FROM DRT TO
FTW AT AROUND 00Z BUT LOOKS AS THOUGH IT IS SLOWING DOWN. EXPECT THE
HEAVY RAIN THREAT TO CONTINUE THROUGH AT LEAST 4 AM.  S/W NEAR
MMTC TRACKING NORTHEAST TOWARD THE UPPER TEXAS COAST MAY AGGRAVATE
THE SITUATION.

45/43/40/35

PREV DISC...
MAIN FORECAST PROBLEM OF THE NIGHT CONCERNS AMOUNT AND EXTENT OF
RAINFALL.  CURRENT RADAR SHOWS LIGHT RAIN OVER THE SOUTHEASTERN HALF
OF SE TX...GENERALLY AHEAD OF THE MID LEVEL VORTICITY CENTER EVIDENT
ON WATER VAPOR AND IR.  00Z SURFACE ANALYSIS SHOWED THE SURFACE LOW
NORTHEAST OF BRO...ABOUT 20 NM SOUTHEAST OF BUOY 42020...WITH A WARM
FRONT NORTH-NORTHEAST OF THE LOW THAT PARALLELS THE COAST.  THE BEST
850 MB MOISTURE WAS OVER THE TX COASTAL PLAIN WITH THE BEST 700 MB
MOISTURE RIGHT ALONG THE MID AND UPPER TX COAST.  THE BEST DIFFLUENT
AREA AT 300 AND 200 MB WAS WELL OFFSHORE.  THE RUC AND AVN LOOK TO BE
THE BEST MODELS OVER THE NEXT 12 HOURS.

SEVERE WEATHER IS NOT A CONCERN OVERNIGHT WITH THE WARM SECTOR AND
BEST DYNAMICS OFFSHORE.  WOULD EXPECT THE HEAVY RAINFALL TO GENERALLY
STAY NEAR AND ALONG THE WARM FRONT OFFSHORE AS THE SURFACE LOW MOVES
TO THE NORTHEAST.  THERE IS A SMALL CONCERN FOR STORMS DEVELOPING NEAR
THE 500 MB VORTICITY CENTER.  THE RUC KEEPS THIS FEATURE A BIT EAST OF
THE AVN FORECAST...RIGHT OVER THE COASTAL COUNTIES AS IT MOVES
NORTHEAST.  AGREE WITH HPC IN LOWERING THE FLASH FLOOD THREAT OVER THE
AREA.  WILL CONTINUE THE FLOOD WATCH OVER THE TWO TIER OF COUNTIES
NEAR THE COAST GIVEN THE LOW FLASH FLOOD GUIDANCE NUMBERS FOR THE 1
AND 3 HOUR PERIODS.  WILL ALSO MAKE CHANGES TO THE FORECAST TO TAKE
OUT THUNDERSTORM CHANCES OVER MOST OF THE INLAND COUNTIES EXCEPT WHERE
THE FLOOD WATCH IS IN EFFECT.

PL-40
34

.HGX...FFA SOUTHEAST THIRD OF SE TX TONIGHT.

PREV PRELIMS...
CLL ET 057/065 058/067 057 633
IAH ET 063/070 062/070 060 953
GLS ET 067/074 068/072 067 +53

GMZ300-330-335-350-355-370-375-TXZ163-164-176>179-195>200-210>214-226-
227-235>238-291100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
330 PM CST MON OCT 28 2002

...FLOOD WATCH IN EFFECT TONIGHT ACROSS THE SOUTHEAST HALF OF
SOUTHEAST TEXAS...
...SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT AREA WIDE...

.DAY ONE...
TONIGHT...
AN UPPER LEVEL DISTURBANCE APPROACHING FROM THE WEST AND A WARM FRONT
MOVING NORTH FROM THE GULF OF MEXICO WILL CONTINUE TO TRIGGER
NUMEROUS SHOWERS AND THUNDERSTORMS OVER THE WATCH AREA TONIGHT.
RAINFALL TOTALS OF AROUND AN INCH WITH ISOLATED TOTALS OF 2 TO 3
INCHES HAVE OCCURRED SO FAR TODAY MAINLY SOUTH OF HIGHWAY 59.
ADDITIONAL RAINFALL AMOUNTS OF 1 TO 2 INCHES WITH ISOLATED TOTALS TO 3
INCHES ARE EXPECTED ACROSS THE WATCH AREA BY MORNING.

RAINFALL WHICH OCCURRED THE LAST WEEK ACROSS SOUTHEAST TEXAS
HAS RESULTED IN A SATURATED GROUND WITH MANY RIVERS AND STREAMS NEAR
BANKFULL OR FLOOD STAGE. THEREFORE...ADDITIONAL HEAVY RAIN WILL
LIKELY CREATE FLOODING ACROSS SOME LOCATIONS.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS ALL OF SOUTHEAST
TEXAS THROUGH TONIGHT. ISOLATED TORNADOES ARE THE PRIMARY SEVERE
WEATHER THREAT...WITH LARGE HAIL AND DAMAGING WINDS ALSO POSSIBLE.

.SPOTTER CALL TO ACTION STATEMENT...SPOTTER ACTIVATION IS POSSIBLE
TONIGHT.

.DAYS TWO THROUGH SEVEN...
TUESDAY THROUGH SUNDAY...HAZARDOUS WEATHER IS NOT EXPECTED.

TXZ178-179-199-200-211>214-226-227-236>238-290800-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
827 PM CST MON OCT 28 2002

...TORNADO WATCH IS IN EFFECT UNTIL 2 AM CST EARLY TUESDAY MORNING
FOR PARTS OF SOUTHEAST TEXAS...

THE STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH UNTIL 2 AM CST
FOR THE FOLLOWING COUNTIES: AUSTIN...FORT BEND...HARRIS...LIBERTY
SAN JACINTO...WHARTON...BRAZORIA...GALVESTON...MATAGORDA...
CHAMBERS...MONTGOMERY...POLK AND WALLER.

A SLOW MOVING WARM FRONT AND FAVORABLE UPPER LEVEL WINDS HAVE CREATED
A FAVORABLE ENVIRONMENT FOR TORNADIC THUNDERSTORMS TO DEVELOP.
THEREFORE...THE STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH
FOR A LARGE PART OF SOUTHEAST TEXAS. STRONG TO SEVERE THUNDERSTORMS
WILL PERSIST THROUGH AT LEAST MIDNIGHT. IN ADDITION TO TORNADOES...
FLOODING RAINS WILL LIKELY CONTINUE ALONG WITH THE THREAT FOR
DAMAGING STRAIGHT LINE WINDS AND SMALL HAIL.

STAY TUNED TO NOAA WEATHER RADIO OR OTHER WEATHER NEWS SOURCES FOR
FURTHER UPDATES AND POSSIBLE WARNINGS.