Severe Thunderstorm Warning 54, NWS Austin/San Antonio, TX

SOUTH CENTRAL TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
315 PM CDT FRI MAY 4 2001

WILL EXTEND THE FLASH FLOOD WATCH EAST INTO CENTRAL AND NORTHEASTERN
SECTIONS OF SOUTH CENTRAL TEXAS THIS AFTERNOON AS MOST MODELS DRAG A
SLOW MOVING COMPLEX OF THUNDERSTORMS THROUGH THE AREA TONIGHT. ETA
MODELS WHILE SHOWING POOR PERFORMANCE ON PRECIP FORECASTING HAVE
DONE WELL ON PRECIPITABLE WATER VALUES. STRONG SHORTWAVE LIFTING OUT
OF MEXICO IS TRIGGERING CURRENT THUNDERSTORM ACTIVITY, AND NORTHEAST
MOVEMENT OF THE SHORTWAVE COMBINED WITH GOOD DIFFULENCE ALOFT WILL
ALLOW FOR HEAVY RAINS TO MOVE OVER THE PROPOSED WATCH AREA.
SOUTHEAST COUNTIES MAY MISS OUT ON THE HEAVIEST PART OF THE SQUALL
SO WILL ONLY MENTION LOCALLY HEAVY RAINFALL HERE. LATE TOMORROW THE
AREA WILL LIKELY SEE ANOTHER GOOD FLARE UP OF ORGANIZED
THUNDERSTORMS AND A CHANCE FOR FLOODING, BUT WILL NOT EXTEND THE
WATCH WITH UNCERTAINTY IN WHICH AREAS WILL RECEIVE HEAVIEST RAINS
FOR TONIGHT. GUIDANCE TEMPERATURES LOOK APPROPRIATELY MILD FOR THE
NEXT FEW DAYS.

MODELS GOING IN DIFFERENT DIRECTIONS BEYOND TUESDAY WITH 12Z AVN
ACCELERATING THE UPPER LOW POSITION TO SUPPORT DRY WEATHER OVER
SOUTH TX WEDNESDAY. GUIDANCE NUMBERS CLOSE TO CLIMO, BUT CLIMO EVEN
CALLS FOR A CHANCE OF RAIN. MRF SUGGESTS NW FLOW PATTERN LATE IN THE
WEEK AND WHILE NOGAPS SUGGESTS PROLONGED INSTABILITY IN THE BAJA
REGION. THUS CAN NOT RULE OUT AT LEAST SLIGHT CHANCE POPS FOR ANY
DAY THROUGH NEXT FRIDAY.

PRELIMINARY NUMBERS...
AUS 68/79/70/84 8662
DRT 67/85/69/89 6432
SAT 69/80/70/84 6642

.EWX...FLASH FLOOD WATCH THROUGH TONIGHT FOR ALL OF THE SOUTH        ?
       CENTRAL TEXAS AND THE HILL COUNTRY EXCEPT FOR FAR SOUTHEAST
       COUNTIES.

18

TXZ171-172-183>190-202>204-050200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
145 PM CDT FRI MAY 4 2001

...SEVERE THUNDERSTORMS POSSIBLE IN THE HILL COUNTRY THIS AFTERNOON
AND TONIGHT...

A DEVELOPING LINE OF THUNDERSTORMS IS MOVING ACROSS VAL VERDE
COUNTY.  THIS LINE IS EXPECTED TO CONTINUE MOVING TOWARD THE EAST AT
20 MPH THIS AFTERNOON AND INCREASE IN AREAL COVERAGE AND INTENSITY.
SOME OF THE STORMS COULD APPROACH SEVERE LIMITS...WHICH MEANS THAT
LARGE HAIL...GUSTY DAMAGING WINDS...FREQUENT DEADLY LIGHTNING AND
LOCALLY HEAVY RAINFALL WHICH COULD PRODUCE FLASH FLOODING MAY OCCUR.

THE AREA WITH THE GREATEST RISK OF SEVERE THUNDERSTORMS IS THAT
PORTION OF THE TEXAS HILL COUNTRY WEST OF INTERSTATE 35 BETWEEN SAN
ANTONIO AND GEORGETOWN...AND ALONG AND NORTH OF U.S. HIGHWAY 90
BETWEEN SAN ANTONIO AND DEL RIO.

THIS OUTLOOK APPLIES TO THE FOLLOWING SPECIFIC COUNTIES...

GILLESPIE...MEDINA...KENDALL...REAL...BLANCO...KERR...BURNET...
BANDERA...LLANO...EDWARDS...KINNEY...UVALDE AND VAL VERDE.

ABUNDANT LOW-LEVEL MOISTURE OVER SOUTH TEXAS...COMBINED WITH AN
APPROACHING UPPER-LEVEL DISTURBANCE FROM MEXICO...WILL PRODUCE
WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON AND
TONIGHT.  SOME OF THE STORMS COULD BE SEVERE.  IN ADDITION...A FLASH
FLOOD WATCH IS IN EFFECT FOR MUCH OF THE HILL COUNTRY AND ADJACENT
SECTIONS OF THE EDWARDS PLATEAU THROUGH TONIGHT.

SPOTTER NETWORKS MAY NEED TO BE ACTIVATED AS THE THUNDERSTORMS
MOVE INTO THE THREATENED AREA.

FOR INFORMATION ON WEATHER THREATS IN SURROUNDING AREAS...REFER
TO OUTLOOKS FROM OFFICES IN MIDLAND...SAN ANGELO...FORT WORTH...
HOUSTON/GALVESTON AND CORPUS CHRISTI.