Severe Thunderstorm Warning 98, NWS Houston/Galveston, TX

SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
755 PM CDT MON AUG 26 2002

UPDATED 1ST PERIOD OF ZFPHGX TO REFLECT CURRENT CONVECTIVE TREND.
CLUSTER OF STRONG TO SEVERE THUNDERSTORMS OVER WESTERN SECTIONS OF
LCH CWFA EXPANDING SOUTHWEST TOWARDS LIBERTY AND CHAMBERS COUNTIES
AND WILL ALSO AFFECT EASTERN COASTAL MARINE ZONES (INCLUDING GLS
BAY). EXPECT CONVECTION TO WEAKEN LATER THIS EVENING AND DECREASE IN
AREAL COVERAGE.

37/45/DO

.HGX...NONE.

CLL BB 075/097 075/097 075 232
IAH BB 077/095 076/095 076 332
GLS BB 081/092 080/090 079 422

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PREVIOUS DISCUSSION..
MAIN WEATHER FEATURES THIS PERIOD WILL BE THE DRIFTING OF THE UPPER
HIGH TO THE WEST AND THE POSITIONING OF AN UPPER LOW TO THE EAST
ALONG WITH THE POSITIONING OF THE FRONT OVER THE RED RIVER.  FORECAST
ITEMS TO CONSIDER ARE POPS AND TEMPERATURES.  THE MODELS DO NOT LOOK
TO BE DOING A VERY GOOD JOB AT PARAMETERIZATIONS...ESPECIALLY THE QPF
FIELD.  OTHERWISE THE ETA WAS A BIT SLOWER AT MOVING THE LOW SOUTH
FROM THE OHIO VALLEY THAN THE AVN.

THE SUBTROPICAL RIDGE GOT REALLY SQUEEZED TO THE SOUTH OVER THE
EASTERN GULF OF MEXICO AS THE HIGH TO THE WEST POSITIONED ITSELF OVER
NORTHWESTERN MEXICO THIS MORNING.  THE 12Z 300 AND 200 MB LEVELS
SHOWED THE UPPER LOW OVER THE OHIO VALLEY...AND THE AVN POSITIONS IT
INTO THE NORTHERN GULF OF MEXICO BY THURSDAY NIGHT OR FRIDAY MORNING.
THE MODELS ALSO TRY TO SAG THE FRONT SOUTH INTO SOUTHERN LA AND FAR SE
TX BY THURSDAY.  THINK THAT MAY BE A BIT UNREALISTIC...AT BEST SOME
DRIER AIR WILL FILTER SOUTHWARD AS THE UPPER LOW MOVES SOUTH AND WEST.
WEST WINDS TODAY PLAYED HAVOC WITH THE SEABREEZE AND PRODUCED
TEMPERATURES TOWARD THE MID 90S AT THE COAST THIS AFTERNOON.  THE
WINDS SHOULD BACK TO THE SOUTHWEST TONIGHT AND TUESDAY...THOUGH THIS
SHOULD AGAIN PRECLUDE THE SEABREEZE.  RAIN CHANCES LOOK TO DROP
THURSDAY AND FRIDAY...THE PICK BACK UP TO SCATTERED SUNDAY AND MONDAY
AS THE UPPER LOW OR UPPER TROUGH MOVES OVERHEAD.  FOR TEMPERATURES
THINK THAT THE MAV AND FWC LOOK A BIT TOO HIGH WELL INLAND AND ARE
FAIRLY CLOSE TOWARD THE COAST.  THE FWC AND MAV LOOK TOO LOW FOR THE
MIN TEMPERATURES.

FOR THIS EVENING WILL KEEP THE BEST POPS NORTH AND EAST.  THE
ATMOSPHERE LOOKS FAIRLY UNSTABLE NORTHEAST...ACARS/MAPS SOUNDINGS SHOW
CAPES AT OR ABOVE 2500 AND AN INVERTED V-TYPE SOUNDING IN THE LOWER
LEVELS.  SOME CONVECTION LOOKS TO FINALLY GETTING GOING IN THE NORTH.
CURRENT ACARS IAH SOUNDING SHOWS SUBSIDENCE IN THE MID AND UPPER
LEVELS...LEADING TO THE IDEA THAT ONLY ISOLATED AT BEST WILL OCCUR
OVER THE WESTERN HALF THIS EVENING.  GIVEN THE ORIENTATION OF THE
RIDGE OVER THE AREA...THINK THE BEST POPS...WITH A CHANCE OF SEVERE...
WILL BE NORTHEAST AND EAST AS CURRENTLY DEPICTED IN THE FORECAST.

PL-40
33
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