Tornado Warning 42, NWS Houston/Galveston, TX

SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
210 PM CST MON DEC 23 2002

THE MAIN 500 MB TROUGH WAS BEGINNING TO AFFECT NM AND FAR WESTERN TX
EARLY THIS AFTERNOON.  SHORTWAVE TROUGHS AHEAD OF THIS SYSTEM HELPED
SET OFF THE STORMS CURRENTLY OCCURRING OVER SE TX.  FOR TONIGHT THE
FORECAST PROBLEM INCLUDES SEVERE STORMS AND HEAVY RAINFALL.  ITEMS
FOR TUESDAY THROUGH MONDAY INCLUDE SKY COVER TUESDAY...THEN THE
TEMPERATURES THROUGHOUT THE PERIOD.  THE MODELS WERE A BIT DIFFICULT
TO FIGURE.  THE ETA ACTUALLY LOOKS GOOD FOR TONIGHT...THOUGH CANNOT
FIND BIG DIFFERENCES AT 500 MB BETWEEN THE ETA AND GFS FOR THE 24 TO
60 HOUR FORECAST.  THE ECMWF WAS WEAKER WITH THE NEXT TROUGH TO PASS
OVERHEAD THURSDAY NIGHT AND FRIDAY.  WILL OPT FOR A COMPROMISE BETWEEN
THE ETA AND GFS INTO DAY 3...THEN THE ECMWF.

OUR THINKING HERE IS THAT THE TORNADO THREAT WILL CONTINUE INTO EARLY
THIS EVENING.  THIS WILL BE THE CASE EVEN THOUGH THE WARM FRONT HAS
MOVED NORTH OF HUNTSVILLE AND CROCKETT.  THE NEXT SHORTWAVE TROUGH
WAS COMBINING WITH SOME INSULATION TO FIRE UP MORE STORMS TO THE
SOUTH OF THE FRONT.  ISOLATED TORNADOES WILL BE THE MAIN THREAT WITH
THESE.  THEN EXPECT A SQUALL LINE TO DEVELOP AHEAD OF THE MAIN 500 MB
SHORTWAVE TROUGH TONIGHT.  THE ETA PUSHES THIS FEATURE THROUGH BY
AROUND 06Z...WHILE THE GFS WAITS UNTIL BETWEEN 06Z AND 12Z. AM LEANING
TOWARD THE ETA SOLUTION IN THIS REGARD...AND FEEL THE COLD FRONT WILL
MOVE THROUGH CLL BETWEEN 03Z AND 05Z...THEN TO THE COAST BETWEEN 06Z
AND 09Z.  THE MAIN THREAT WILL BE STRONG WINDS AND HAIL...ISOLATED
TORNADOES WILL BE POSSIBLE...GIVEN THE FORECAST CAPES AND HELICITY.
THE ETA BUFR AT GLS AT 06Z SHOWED A CAPE OF 3453 AND 0-3KM HELICITY OF
342.

FOR TUESDAY THE RAINFALL LOOKS TO BE AT AN END EXCEPT ALONG THE COAST
EARLY...THOUGH THE CLOUD COVER MAY BE SLOW TO ERODE.  THE MAIN 500 MB
TROUGH MOVES ACROSS BY THURSDAY...THOUGH THE UPPER JET DRIFTS
NORTHWARD ACROSS TEXAS. EXCEPT FOR THURSDAY NIGHT AND FRIDAY WHEN THE
TROUGH MOVES ACROSS...PARTLY CLOUDY SKIES SHOULD PREVAIL.  WILL STAY
CLOSE TO THE FWC AND MAV GUIDANCE FOR TEMPERATURES.

PL-40
30

.HGX...FLASH FLOOD WATCH ALL OF SOUTHEAST TEXAS.
       SCA GALVESTON AND MATAGORDA BAYS.
       SCA 00 TO 60 NM HIGH ISLAND TO THE MATAGORDA SHIP CHANNEL.

PRELIMS...
CLL EB 042/050 030/053 031 710
IAH EB 048/054 033/053 031 710
GLS EB 052/057 040/051 042 620

GMZ300-330-335-350-355-370-375-TXZ163-164-176>179-195>200-210>214-226-
227-235>238-241300-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
553 AM CST MON DEC 23 2002

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST TEXAS AND
THE UPPER TEXAS COASTAL WATERS.

...TORNADO OUTBREAK ACROSS SOUTHEAST TEXAS APPEARS IMMINENT...

.DAY ONE...
.TODAY...A WARM FRONT DRAPED ACROSS SOUTHEAST TEXAS AND VERY STRONG
SOUTHERLY WINDS THAT VEER FROM SOUTH TO WEST IN THE LOWER PORTIONS OF
THE ATMOSPHERE WILL COMBINE WITH COOLING TEMPERATURES ALOFT TO AID THE
DEVELOPMENT OF THUNDERSTORMS ACROSS THE AREA THIS MORNING. A POWERFUL
DISTURBANCE IN THE JETSTREAM WILL MOVE INTO THE AREA THIS AFTERNOON
BRINGING A LAYER OF COLDER AND DRIER AIR ALOFT THAT WILL ENHANCE THE
POTENTIAL FOR VERY DANGEROUS THUNDERSTORMS THAT COULD HAVE LONG LIVED
STRONG TO SEVERE TORNADOES. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE
AND A FLASH FLOOD WATCH IS IN EFFECT THROUGH TONIGHT. A SQUALL LINE
WILL LIKELY DEVELOP LATE THIS AFTERNOON OR EARLY EVENING TO THE WEST
OF THE REGION AND RACE EAST THROUGH THE AREA. STRONG DAMAGING WINDS
WILL LIKELY ACCOMPANY THIS SYSTEM. THE SQUALL LINE SHOULD BE NEARING
THE COAST LATE TONIGHT OR VERY EARLY TUESDAY MORNING. MARINERS SHOULD
AVOID GOING OUT ON THE WATER TONIGHT.

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

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS ANTICIPATED BY AROUND 9 AM. SPOTTERS AND
EMERGENCY MANAGEMENT SHOULD PLAN FOR ACTIVATION TO CONTINUE THROUGH
MIDNIGHT.