Severe Thunderstorm Warning 9, NWS Houston/Galveston, TX

SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
945 AM CST FRI FEB 21 2003

TORNADO WATCH WILL BE EXTENDED AS PER CONFERENCE CALL W/SPC. SURFACE
FRONT EXPECTED TO MOVE FARTHER NORTH IN RESPONSE TO DEVELOPING LOW PRESSURE
NEAR COASTAL BEND. CURRENT CONVECTION OVER REGION MAINLY ALONG AND
NORTH OF FRONT WITH STRONGER STORMS NORTH OF CWFA. SURROUNDING
SOUNDINGS INDICATE VERY HIGH PWATS (FOR THIS TIME OF THE YEAR) W/LCH
AT 1.52 INCHES. MORE UNSTABLE TO THE SOUTH W/CRP SHOWING LIFTED
INDEX AT MINUS 4. 15Z MSAS INDICATE STRONG SURFACE MOISTURE CONVERGENCE
ALONG AND JUST SOUTH OF WARM FRONT. FRONT EXTENDS FROM LIBERTY
COUNTY TO COLORADO COUNTY. FRONT IS BETWEEN HOU AND IAH. 850 MB
ANALYSIS INDICATE MOISTURE TONGUE (14 DEG C DEWPOINT) RIGHT OVER
CWFA. WITH THE AIRMASS BECOMING MORE UNSTABLE AS THE DAY
PROGRESSES...WE SHOULD EXPECT DEVELOPING CONVECTION TO BECOME
STRONGER. CAPE AND LIS WILL INCREASE BY THIS AFTERNOON. HELICITY
VALUES ARE AMPLE TO PRODUCE SUPERCELLS.

VISIBILITIES ARE IMPROVING INLAND AREAS...BUT PATCHY DENSE FOG
SHOULD CONTINUE OVER CHAMBERS AND GALVESTON COUNTIES.

37/41/47

.HGX...FFA ALL OF SE TX.
       TORNADO WATCH FOR ALL OF SE TX.
       SCEC ALL MARINE AREAS.

CLL TB 061/049 069/045 070 +30
IAH TB 066/052 069/047 071 +20
GLS TB 068/055 066/057 068 +30

PREVIOUS DISCUSSION...
AT 06Z...SFC ANALYSIS SHOWED AN AREA OF DEVELOPING LOW PRESSURE
BETWEEN BRO AND LRD WITH A TROF OF LOW PRESSURE EXTENDING NE ALONG
THE COAST AND INTO S LA. PRECIP CONTINUES TO FIRE ALONG THIS BNDRY.
AT 85H...LOW PRESSURE WAS ALSO SHOWING UP BETWEEN LRD AND BRO. S-SE
WINDS OF 30 KTS ON THE EAST OF THIS FEATURE WAS HELPING TO PROVIDE
THE INFLOW TO KEEP THE ACTIVITY GOING. AT 25H...SE TX IS STILL IN A
RRQ/LFQ COUPLET AND UPPER LEVEL WINDS REMAIN DIVERGENT. IT SEEMS
THAT ALL INGREDIENTS ARE IN PLACE FOR AN ACTIVE DAY OF WEATHER.

THE SFC LOW NEAR BRO WILL INTENSIFY AND SCOOT UP THE COAST AS A DEEP
50H TROF CROSSES THE STATE. PWS WILL REMAIN BETWEEN 1.25 AND 1.45
INCHES TODAY...MORE THAN SUFFICIENT FOR HEAVY RAIN FOR THIS TIME OF
YEAR. BOTH THE ETA AND AVN ARE IN GOOD AGREEMENT WITH SHUTTING OFF
THE RAIN BY EVENING.

SPC HAS PLACED ALL OF SE TX IN EITHER SLIGHT OR MODERATE RISK FOR
TODAY. THE COUNTIES WHICH LIE IN THE WARM SECTOR OF THE APPROACHING
LOW FACE THE GREATEST RISK OF SEVERE WEATHER. THINK THE GREATEST
RISK WILL BE AREAS EAST OF THE U.S. 59 CORRIDOR. STORM MOTION HAS
BEEN PRETTY QUICK...GENERALLY 20-25 KNOTS...SO FLOODING THUS FAR HAS
BEEN CONFINED TO AREAS THAT SAW REPEAT ECHOES. STILL FEEL FLOODING
IS A LEGITIMATE CONCERN TODAY AS 85H DEW POINTS REMAIN AOA 10C...
HIGH PWS AND THE AFOREMENTIONED JET COUPLET. WILL KEEP FFA AS
CONFIGURED BUT THINK THE GREATEST CHANCE FOR HEAVY RAIN WILL BE
AREAS NEAR THE COAST WHERE THE BEST LOW LEVEL CONVERGENCE IS
LOCATED. KHGX 88-D APPEARS TO BE OVERESTIMATING RAINFALL BY ABOUT 10
PERCENT. WILL SEND OUT HWOHGX EARLY WITH ALL THE DETAILS.

UPCOMING WEEKEND LOOKS OK. PCLDY SKIES WITH A WARMING TREND. IN THE
LATER PERIODS...WILL REMAOVE MENTION OF THUNDER FOR MON/TUE. NEXT
UPPER LEVEL TROF AND COLD FRONT COMES THROUGH WED/THU AND WILL
KEEP POPS GOING THRU THURSDAY. THEN IT LOOKS LIKE ANOTHER RAIN MAKER
NEXT WEEKEND. 43/40

TXZ163-164-176>179-195>200-210>214-226-227-235>238-221300-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1135 AM CST FRI FEB 21 2003

...THREAT FOR LOCALLY HEAVY RAINFALL AND SEVERE STORMS ACROSS
SOUTHEAST TEXAS THIS AFTERNOON AND THIS EVENING...
...FLOOD WATCH IN EFFECT TODAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

AN APPROACHING UPPER LEVEL STORM SYSTEM FROM THE WEST COMBINED WITH
A WARM FRONT PUSHING INLAND AND DEEP MOISTURE ALREADY IN PLACE WILL
PROVIDE A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON
THROUGHT THE EVENING HOURS.

SOME LOCATIONS ACROSS THE NORTHERN THIRD OF SOUTHEAST TEXAS RECEIVED
4 TO 6 INCHES OF RAINFALL YESTERDAY. SOME ROAD FLOODING IS ONGOING
AND CREEKS AND RIVERS ARE ON THE RISE. ANOTHER 1 TO 2 INCHES OF
RAINFALL CAN BE EXPECTED ACROSS ALL OF SOUTHEAST TEXAS THROUGH THIS
EVENING...WITH ISOLATED 4 INCH AMOUNTS POSSIBLE WHERE TRAINING HEAVY
DOWNPOURS OCCUR. MOTORISTS SHOULD BE ON THE LOOKOUT FOR STANDING
WATER ON ROADS AND ARE UNGED NOT TO DRIVE ACROSS THEM.

IN ADDITION...THE ATMOSPHERIC WIND PROFILE WILL FAVOR THE POSSIBILITY
OF A FEW STORMS BECOMING SEVERE. LARGE HAIL WILL BE THE PRIMARY
SEVERE WEATHER THREAT...WITH ISOLATED TORNADOES AND 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.

PRECIPITATION SHOULD COME TO AN END THIS EVENING AS THE STORM SYSTEM
PASSES EAST OF THE AREA.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATER THIS AFTERNOON.