Flash Flooding and Hail in Texas, May 10, 2007

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
615 PM CDT THU MAY 10 2007

.UPDATE...CONVECTION CONTINUES TO DEVELOP NORTHWEST AND WEST OF
THE CWA EARLY THIS EVENING AND BEGINNING TO DEVELOP ACROSS
WESTERN AND NORTHWEST PORTIONS OF SOUTHEAST TEXAS. HAVE ALREADY
UPDATED GRIDS/ZONES TO MENTION SEVERE STORMS WITH SEVERE
THUNDERSTORM WATCH JUST ISSUED FOR THE WESTERN AND SOUTHWEST
PORTIONS OF THE CWA INCLUDING HARRIS AND MONTGOMERY COUNTIES. 32
&&

.PREV DISCUSSION... /ISSUED 402 PM CDT THU MAY 10 2007/
ACTIVITY HAS BEEN SLOW TO START THIS AFTN BUT WE SHOULD START TO
SEE THINGS PICK UP AS THE UPPER LOW APPROACHES (FROM THE NW) DUR-
ING THESE PEAK HEATING HOURS. PER ANALYSES/SPC OUTLOOKS...WE ARE
ON THE MARGINALLY FAVORABLE AREA FOR SEVERE LATER THIS AFTN INTO
THE EARLY EVENING. COOLER TEMPS ALOFT STILL THE PROMINENT FACTOR
FOR THE THREAT OF HAIL. RECENT MCD DISCUSSING THE POSSIBILITY IN
THE SHORT TERM. WILL KEEP THE HIGHISH POPS FOR THE FIRST PART OF
THE EVENING TIMEPERIOD...AND WILL ALSO KEEP CHC POPS IN THE AREA
FOR TOMORROW. THE PROXIMITY OF THE LOW/DAYTIME HEATING/LINGERING
MOISTURE THE BOXES CHECKED FOR TOMORROW. WEEKEND FCST (AND SEEM-
INGLY MOST OF NEXT WEEK) LOOKS VERY SUMMERLIKE. A PERSISTENT E/W
UPPER TROFFINESS TO KEEP THE AIRMASS SOMEWHAT UNSTABLE...AND COM-
BINED WITH AFTN HEATING AND AN APPARENT SFC BOUNDARY APPROACHING
AND STALLING FROM THE NORTH TO WARRANT LOW/UBIQUITOUS 20% POPS
IN OUR FCST. TEMPS TO STAY IN THE NORMAL RANGE. THIS RATHER UNRE-
MARKABLE UPPER PATTERN (SE TX HOVERING IN BETWEEN THE RIDGE WEST
OF US AND THE TROF TO THE EAST) COULD CHANGE LATER NEXT WEEK PER
EXTENDED MODELS. AS THE RIDGE RETROGRADES SLIGHTLY WEST...A MORE
PRONOUNCED TROF TO DEVELOP ALOFT AND WE COULD SEE AN UPWARD JUMP
IN POPS FOR THIS TIMEFRAME. 41

AVIATION...
WEATHER MUCH SLOWER TO DEVELOP SO HAVE SHIFTED TSRA BACK 2 TO 4
HOURS. STILL HAVE IMPRESSIVE DIVERGENCE TO MOVE ACROSS THE REGION
LATE THIS AFTERNOON AND EVENING AND EXPECT TO SEE SHOWERS AND
THUNDERSTORMS DEVELOP AND TRAVERSE THE AREA ROTATING AROUND THE
UPPER LOW. STORMS SHOULD BE EAST OF THE AREA AND OUT OVER THE WATER
BY 04Z. A FEW ISOLATED STORMS MAY REDEVELOP BACK IN CLOSE BENEATH
THE UPPER LOW 03-09Z BUT CONFIDENCE IS LOW ENOUGH THAT WILL
PROBABLY ONLY MENTION VCSH/VCTS FOR MOST OF THE INLAND TERMINALS.

WILL GO WITH VCTS AS IT IS MORE IFFY DUE TO THE SEABREEZE.
45

MARINE...
VERY QUIET OVER THE WATERS. SOUTHERLY FLOW AROUND 10 KNOTS WILL
WEAKEN WITH THE UPPER LOW MOVING INTO SOUTHEAST TEXAS LATE TONIGHT.
AFTER TONIGHT GRADIENT IS VERY WEAK AND WINDS WILL BE LIGHT AND
VARIABLE FOR THE NEXT 3 TO 4 DAYS.
45
&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      63  83  64  85  65 /  60  30  20  20  20
HOUSTON (IAH)              64  82  65  85  65 /  60  30  20  20  20
GALVESTON (GLS)            69  80  69  81  71 /  60  40  30  10  10
&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

DISCUSSION...32

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
629 PM CDT THU MAY 10 2007

TXZ163-164-176>179-195>200-210>214-226-227-235>238-111015-
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA-
MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON-
WHARTON-
629 PM CDT THU MAY 10 2007

...SLIGHT RISK OF SEVERE WEATHER FOR WESTERN AND SOUTHERN PORTIONS
OF SOUTHEAST TEXAS THIS EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...TONIGHT

A SLIGHT RISK OF SEVERE THUNDERSTORMS REMAINS POSSIBLE FOR THE
WESTERN AND SOUTHERN PARTS OF SOUTHEAST TEXAS TONIGHT.
LOW LEVEL MOISTURE CONTINUES TO RETURN TO THE AREA...AS THE
ATMOSPHERE CONTINUES TO DESTABILIZE AS COLD AIR ALOFT ASSOCIATED
WITH AN UPPER LEVEL DISTURBANCE MOVES OVER WARM MOIST AIR NEAR THE
SURFACE. STRONG LIFT ASSOCIATED WITH THE DISTURBANCE WILL HELP
INITIATE THUNDERSTORM ACTIVITY MAINLY THIS EVENING INTO EARLY
FRIDAY MORNING. THE MAIN THREATS WILL BE DAMAGING DOWNBURST WINDS
AND HAIL WITH THESE STORMS. LOCALLY HEAVY RAINFALL MAY BE ANOTHER
THREAT AS STORMS ARE STILL EXPECTED TO MOVE SLOWLY ACROSS THE
AREA. THIS MAY CONTRIBUTE TO LOCALIZED FLASH FLOODING IN AREAS
WHERE GROUNDS ARE ALREADY SATURATED.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

HAZARDOUS WEATHER IS NOT EXPECTED.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE NEEDED TONIGHT.