Tornado Warning 45, NWS Houston/Galveston, TX

SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
220 AM CST MON NOV 17 2003

SCT CONVECTION IS ALREADY BREAKING OUT W AND SW OF SE TX TONIGHT
WHERE THE LLJ IS INCREASING. CONVECTION IS EXPECTED TO INCREASE OVER
SE TX THIS MORNING...BECOMING WIDESPREAD BY MID-DAY.

MAIN FORECAST ISSUES ARE FLOOD AND SVR TSTM THREAT. WHAT TO SAY
THAT HAS NOT ALREADY BEEN SAID? IN A NUTSHELL...PARAMETERS ARE ALL
IN PLACE FOR A FLASH FLOOD AND SVR TSTM THREAT TODAY AND TONIGHT.
EXPECT THE EXIT REGION OF THE UPPER LEVEL JET TO PROVIDE SIGNIFICANT
DIVERGENCE ALOFT THIS MORNING AND COUPLED WITH A LITTLE
HEATING...WILL PROVIDE FOR AN EXPLOSIVE ENVIRONMENT OVR SE TX. WITH
LOW-LEVEL HELICITIES IN THE 200-300 RANGE LATER THIS MORNING AND
DURING THE AFT HOURS...IT APPEARS THAT THERE WILL BE A TORNADO
THREAT OUT AHEAD OF A SQUALL LINE THAT SHOULD PUSH THROUGH THE
REGION TONIGHT AS MID-LEVEL WINDS REALLY STRENGTHEN WITH THE
APPROACH OF THE UPPER LEVEL TROUGH. DAMAGING WINDS/LARGE HAIL ARE
LIKELY TO BE THE PRIMARY THREATS TONIGHT. TWO ITEMS THAT HAVE CAUGHT
MY ATTENTION WITH THIS UPCOMING EVENT ARE THE MODEL FORECASTS OF
NEAR 2 INCH PW OVER SE TX THIS AFT/EVE (RARE FOR NOV) AND THE
STRENGTH OF THE UPPER LEVEL JET CORE OVR SE TX (140 KTS) TONIGHT.
APPEARS THAT THERE WILL BE A GOOD SETUP FOR TRAINING PRECIP IN AN
EXTREMELY MOIST ATMOSPHERE. STILL HAVE A WEAK BOUNDARY IN PLACE FROM
LAST EVENINGS CONVECTION WHICH COULD AID IN FOCUSING PRECIP LATER
TODAY. THEREFORE...FLOOD WATCH IS A GIVEN AND WILL BE EXTENDED
THROUGH TONIGHT.

BEHIND THE FRONT...FROM TUESDAY THROUGH FRIDAY...DRY AND SEASONAL
TEMPS EXPECTED WITH A TEMPORARY WEAK MID-LEVEL RIDGE IN PLACE. DEEP
TROF DEVELOPS ON FRIDAY OVER THE WESTERN U.S. WHICH IS PROGGED TO
AMPLIFY INTO A CLOSED LOW OVR THE CENTRAL PLAINS ON SUNDAY. WILL
HAVE SLIGHT CHC POPS ON SAT AND CHC POPS ON SUN AHEAD OF THIS
FEATURE. IF THIS PATTERN VERIFIES...WILL SEE MUCH COOLER TEMPS TO
START NEXT WEEK.

WILL HAVE A CAUTION STATEMENT TODAY FOR THE MARINE AREA AS WINDS
SHOULD INCREASE AS GRADIENT TIGHTENS.

33/41

.HGX WATCHES/WARNINGS/ADVISORIES...
 FLOOD WATCH ALL SE TX TODAY AND TONIGHT.
 CAUTION HIGH ISLAND TO MATAGORDA SHIP CHANNEL OUT 60 NM AND BAYS.

PRELIMS...
CLL TU 078/058 072/044 071 8+1
IAH TB 079/063 074/045 071 8+2
GLS TB 081/068 074/054 070 7+4

MONDAY RECORDS FOR GALVESTON:
HIGH MIN 73/1921
REC HIGH 80/1986

TXZ163-164-176>179-195>200-210>214-226-227-235>238-181300-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
700 AM CST MON NOV 17 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST TEXAS.

...FLOOD WATCH TODAY AND TONIGHT...
...SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY AND TONIGHT...

.DAY ONE...TODAY AND TONIGHT
A STRONG STORM SYSTEM WILL APPROACH SOUTHEAST TODAY AND MOVE ACROSS
THE AREA TONIGHT AND EARLY TUESDAY. STRONG WINDS WILL BE PRESENT IN
THE ATMOSPHERE OVER SOUTHEAST TEXAS BY MID-DAY TODAY AND WILL INCREASE
DURING THE AFTERNOON. THESE STRONG WINDS ABOVE THE SURFACE AND
INCREASING INSTABILITY IN THE ATMOSPHERE WILL CREATE AN ENVIRONMENT
FAVORABLE FOR SEVERE THUNDERSTORM DEVELOPMENT. TONIGHT...A SQUALL LINE
IS LIKELY TO MOVE ACROSS SOUTHEAST TEXAS AHEAD OF A COLD FRONT.
THEREFORE...AN ISOLATED SEVERE THREAT DURING THE LATE MORNING AND
EARLY AFTERNOON HOURS MAY INCREASE AS ORGANIZED CONVECTION MOVES
ACROSS THIS EVENING. IT APPEARS THAT TORNADOES...HAIL...AND DAMAGING
WINDS WILL ALL BE THREATS.

IN ADDITION TO THE SEVERE THUNDERSTORM THREAT...HEAVY RAINFALL IS
POSSIBLE TODAY AND TONIGHT AS WELL. FAST MOVING STORMS WILL LIKELY
MOVE REPEATEDLY OVER THE SAME LOCATIONS...CREATING THE HEAVY RAINFALL
THREAT. AVERAGE RAINFALL AMOUNTS ARE EXPECTED TO BE IN THE 2 TO 4
INCH RANGE WITH ISOLATED AMOUNTS OF 6 TO 8 INCHES POSSIBLE.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO END WITH THE COLD FRONT
PASSAGE. THE FRONT IS EXPECTED TO REACH THE COAST TUESDAY MORNING.
DRY CONDITIONS ARE EXPECTED TUESDAY AFTERNOON THROUGH FRIDAY.
HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE REQUIRED LATE THIS MORNING THROUGH
TONIGHT.