River Flood Warning 12, NWS Houston/Galveston, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
326 PM CDT WED AUG 20 2008

.DISCUSSION...
LATEST RADAR IMAGERY SHOWING SCATTERED THUNDERSTORMS WITH HEAVY
DOWNPOURS OVER PORTIONS OF FORECAST AREA....WITH SATELITE SHOWING
PARTIAL CLEARING OVER NORTHERN AND WESTERN PORTIONS OF FORECAST
AREA. EXPECT CONVECTION TO DIMINISH SOME THIS EVENING AS VORT LOBE
LIFTS NORTHEAST OF THE AREA. ANOTHER VORT LOBE PROGGED TO APPROACH
THE AREA FROM THE NW ON THURSDAY...SO EXPECT ANOTHER ROUND OF
SHOWERS AND THUNDERSTORMS GIVEN LIFT AND STILL MOIST AIRMASS.

IN FACT...GFS SHOWS LITTLE CHANGE IN PATTERN THROUGH 7 DAYS...WITH
UPPER TROUGH OVER TEXAS...OCCASIONALLY SHARPENING UP WITH A SHORT
WAVE DIVING INTO THE BASE OF THE FEATURE...AND UPPER RIDGE
DOWNSTREAM ASSOCIATED WITH FAY. THIS IMPLIES CHANCES OF RAIN EVERY
DAY...WITH HIGHEST CHANCES IN AFTERNOON AND EVENING WITH
DESTABILIZATION OF AIRMASS...BUT CHANCES REALLY ANY TIME OF DAY
BASED ON TIMING OF SHORT WAVES AND POSITIONING OF UPPER FEATURES.
STILL SOME UNCERTAINTY UPPER TROUGH NOT AS PRONOUNCED IN THE ECMWF.
46

&&

.MARINE...
MAIN ITEMS OF INTEREST FOR THE MARINE AREAS ARE THUNDERSTORMS IN THE
SHORT TERM AND THEN THE WINDS IN THE LONG TERM. THE UPPER LOW OVER
THE SOUTHERN PLAINS WILL KEEP THE UPPER TEXAS COAST UNDER A
PREFERRED AREA FOR THUNDERSTORMS INTO THURSDAY. THE FUTURE TRACK OF
FAY OVER THE SOUTHEASTERN STATES WILL HELP DETERMINE WIND DIRECITON
AFTER THURSDAY. THE WIND SPEEDS ARE EXPECTED TO GENERALLY REMAIN
BELOW 15 KNOTS. CURRENTLY THE GFS LOOKED REASONABLE IN ITS SOLUTION.
NO ADVISORIES OR CAUTION AREAS ARE EXPECTED.

40

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      71  90  74  92  73 /  40  50  30  40  20
HOUSTON (IAH)              73  89  74  91  74 /  50  60  30  40  20
GALVESTON (GLS)            78  86  79  88  78 /  50  50  30  40  20

&&

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

DISCUSSION...46
MARINE...30

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
334 AM CDT WED AUG 20 2008

TXZ163-164-176>179-195>200-210>214-226-227-235>238-211200-
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-
334 AM CDT WED AUG 20 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...TODAY AND TONIGHT...
AN UNSEASONABLY STRONG UPPER LOW OVER NORTH CENTRAL TEXAS IN
COMBINATION WITH HIGH MOISTURE LEVELS OVER OUR REGION WILL RESULT
IN PERIODS OF SHOWERS AND THUNDERSTORMS. RAINFALL AMOUNTS OF 1 TO
3 INCHES CAN BE EXPECTED. LOCALLY HEAVY RAINFALL AMOUNTS OF 3 TO 5
INCHES WILL BE POSSIBLE. WITH HEAVY RAINFALL THE LAST COUPLE OF
DAYS...FLOODING OF LOW LYING AREAS...UNDERPASSES...FEEDER
ROADS...AND LOW WATER CROSSINGS WILL BE POSSIBLE.

THE HEAVY RAINFALL THREAT WILL START TO DIMINISH TONIGHT AS THE
UPPER LOW STARTS TO MOVE NORTHEAST OUT OF NORTH CENTRAL TEXAS.
HOWEVER...MOISTURE LEVELS WILL REMAIN HIGH. THERE WILL BE A
CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. SOME STORMS MAY
STILL BE CAPABLE OF HEAVY RAINFALL.

.DAY TWO...THURSDAY...
THE UPPER LOW WILL CONTINUE MOVING NORTHEAST TO NEBRASKA WHILE WEAKENING.
MOISTURE LEVELS WILL REMAIN HIGH OVER SOUTHEAST TEXAS. WE SHALL SEE
A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS. SOME STORMS MAY STILL
BE CAPABLE OF HEAVY RAINFALL.

.DAYS THREE THROUGH SEVEN...FRIDAY THROUGH TUESDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.