Severe Thunderstorm Warning 174, NWS Austin/San Antonio, TX

SOUTH CENTRAL TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1026 AM CDT WED AUG 13 2003

ALTHOUGH SATELLITE AND RADAR LOOKS SOMEWHAT UNREPRESENTATIVE OF THE
HIGH POP NUMBERS FOR TODAY AS WELL AS SKY CONDITION, EXPECT THE
STEEP LOW TO MID LEVEL LAPSE RATES WITH DAYTIME HEATING TO QUICKLY
PRODUCE CLOUDS AND RAIN IN THE EARLY AFTERNOON. TEMPERATURES FROM
700 TO 300 MBS WERE ALL SLIGHTLY COOLER FROM SOUNDINGS THAN WERE
SHOWN IN THE 00-06Z MODEL PROJECTIONS. SEVERE THREAT STILL APPEARS
BEST OVER THE WESTERN COUNTIES WHERE WARMER LOW LEVEL TEMPERATURES
WILL MAKE FOR THE STEEPEST LAPSE RATES. RADAR RETURNS ARE SLOWLY
INCREASING AS ARE CLOUDS INDICATED ON SATELLITE VIS. SINCE WINDS AND
TEMPERATURES ARE WELL HANDLED BY THE PREVIOUS FORECAST, DO NOT SEE A
NEED TO UPDATE THE FORECAST LATE THIS MORNING.

.EWX...NONE
18/11

.EARLY MORNING DISCUSSION.....................................
EARLY THIS MORNING A CONVECTIVE COMPLEX ASSOCIATED WITH THE
RETROGRADING MID/UPPER LEVEL LOW PRESSURE SYSTEM WAS MOVING
SOUTHWEST INTO THE HILL COUNTRY.  THE 00Z AVN RUN BEST INITIALIZED
THIS FEATURE AND ASSOCIATED PCPN...THUS WILL BE THE BASIS FOR THIS
FCST.

THE MID/UPPER LOW CENTERED BETWEEN KSEP AND KACT WILL MOVE SOUTHWEST
TODAY SKIRTING THE TEXAS HILL COUNTRY ON THE WAY TO BIG BEND.
CONVECTION ASSOCIATED WITH THIS FEATURE WILL OVERSPREAD MUCH OF THE
CWFA TODAY...WITH LOCALLY HEAVY RAINFALL POSSIBLE. ISOLATED SEVERE
TSTMS ARE ALSO POSSIBLE THIS AFTERNOON FOR THE WESTERN COUNTIES OF
VAL VERDE...KINNEY AND EDWARDS WHERE WARMER AFTERNOON TEMPS ARE
EXPECTED TO DESTABILIZE THE ATMOSPHERE.  RAIN CHANCES WILL DIMINISH
TONIGHT AS THE UPPER LOW MOVES WEST OF THE CWFA AND CONVECTION
CONCENTRATES NEAR THE UPPER LOW.  HOWEVER A DISTURBANCE ROTATING NE
AROUND THE UPPER LOW WILL TRACK ACROSS THE CWFA ON THURSDAY.  THIS
DISTURBANCE WILL TAP INTO TROPICAL MOISTURE ON THE BACKSIDE OF THE
INVERTED UPPER TROF RESULTING IN ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS WITH HEAVY RAINFALL POSSIBLE. DEPENDING ON THE AMOUNT
OF RAINFALL THE CWFA RECEIVES TODAY A FLASH FLOOD WATCH MAY NEED TO
BE POSTED FOR THURSDAY.

THE LOW PRESSURE SYSTEM CURRENTLY LOCATED EAST OF THE BAHAMAS IS
FCST TO CONTINUE TO MOVE WESTWARD INTO THE GULF OF MEXICO AFTER
PASSING OVER FLORIDA.  THE AVN MOVES THIS SYSTEM WESTWARD ACROSS THE
GULF MAKING LANDFALL IN THE KBRO AREA FRIDAY NIGHT.  WILL CONTINUE
SLIGHT CHANCE POPS FRIDAY IN ADVANCE OF THE TROPICAL SYSTEM...WITH
CHANCE POPS SATURDAY AS IT MOVES INLAND AROUND KBRO.

WILL GO WITH A DRY FCST SUNDAY AND MONDAY AS THE UPPER RIDGE BUILDS
OVER THE SOUTHERN PLAINS.  RAIN CHANCES RETURN TUESDAY AS ANOTHER
WEAK TROPICAL SYSTEM TRACKS WESTWARD ACROSS THE GULF TOWARDS THE
TEXAS COAST.

TXZ171>173-183>194-202>209-217>225-228-141100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
508 AM CDT WED AUG 13 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL TEXAS.

.DAY ONE...TODAY AND TONIGHT.
AN UPPER AIR LOW PRESSURE AREA TRACKING ACROSS THE HILL COUNTRY
TODAY ON ITS WAY TO THE BIG BEND WILL HELP TRIGGER SCATTERED SHOWERS
AND THUNDERSTORMS ACROSS THE HILL COUNTRY AND SOUTH CENTRAL TEXAS.
LOCALLY HEAVY RAIN IS A THREAT MAINLY THIS AFTERNOON AND THIS
EVENING FOR ALL AREAS.  RAINFALL AMOUNTS WILL BE NEAR ONE INCH IN
SPOTS. IN ADDITION...ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE THIS
AFTERNOON WEST OF A LINE ROUGHLY FROM ROCKSPRINGS TO LEAKEY TO
SABINAL TO BATESVILLE TO CATARINA.  LARGE HAIL AND DAMAGING WINDS ARE
THE MAIN THREATS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.
ANOTHER UPPER AIR DISTURBANCE WILL TRIGGER ANOTHER ROUND OF SHOWERS
AND THUNDERSTORMS THURSDAY...PRODUCING LOCALLY HEAVY RAINS.
FLASH FLOODING MAY DEVELOP AS SOILS BECOME SATURATED IN SOME AREAS.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE REQUIRED IN THE WESTERN COUNTIES THIS
AFTERNOON.