Severe Thunderstorm Warning 171, NWS Austin/San Antonio, TX

SOUTH CENTRAL TEXAS FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1054 AM CDT TUE AUG 12 2003

UPPER LOW CENTERED NEAR THE TOLEDO BEND RESERVOIR IS MOVING DEEPER
MID LEVEL MOISTURE INTO CENTRAL TX TODAY. CONSIDERING DEWPOINT
DEPRESSIONS ALREADY BELOW 5 DEG CELSIUS AT 700 MBS OVER MUCH OF THE
AREA UPWIND FROM SC TX, THE MOISTURE INCREASE WILL LIKELY RESULT IN
INCREASED CLOUD COVER FOR TODAY AND LIKELY THROUGH THURSDAY. THE
CLOUD COVER WILL IN TURN LOWER THE POTENTIAL FOR DAMAGING WINDS
ALTHOUGH MODIFIED SOUNDINGS STILL SUPPORT CAPES IN EXCESS OF 2000
J/KG. MORNING HELICITIES WILL ADD A ROTATIONAL COMPONENT TO STORMS
OVER WESTERN COUNTIES EARLY, BUT VAD WINDS AT KDLF ALREADY SUGGEST
THIS TO BE A RAPIDLY DIMINISHING CONCERN WITH LOW LEVEL FLOW
BEGINNING TO TRANSITION INTO EASTERLIES/NORTHEASTERLIES. CURRENT
POPS AND SVR ASSESSMENT FROM THE PREVIOUS SHIFT LOOK ON TRACK.

THUS MAIN CHANGES IN THE MORNING UPDATE PERTAIN TO SKY TEMP AND
WIND. WILL KNOCK FIRST PERIOD HIGHS DOWN A NOTCH AND PERHAPS MAKE
SOME SUBTLE REDUCTIONS TO WEDNESDAY MAXES. AM EXPECTING MOSTLY
CLOUDY SKIES FOR THE EASTERN HALF TODAY AND WILL MAKE THE
DIRECTIONAL CHANGES TO WINDS THAT WERE ALREADY SUGGESTED BY THE
EARLY MORNING FORECAST.

.EWX...NONE
18/19

.EARLY MORNING DISCUSSION.........................................
SCT TSRA CONTINUE ACROSS SCNTRL TX EARLY THIS MORNING...INCLUDING A
MINI-SUPERCELL SPLIT OVER REAL COUNTY IN THE LAST 30 MINUTES. THE
MAIN FORECAST ISSUES ARE THREAT OF SEVERE CONVECTION TODAY...HEAVY
RAIN THREAT THU...AND CONTINUING POPS AND TROPICAL RAIN THREAT OVER
THE WEEKEND. THE 00Z NCEP MODELS ARE IN FAIR TO GOOD AGREEMENT...
ALTHOUGH ALWAYS SUSPECT FOR SPECIFICS WITH SO MUCH MESOSCALE
FORCING. WILL BLEND ALL AVAILABLE MODELS. NUMERIC TEMP GUIDANCE
LOOKS TOO COOL AND POP GUIDANCE TOO DRY FOR DAYS1-2. WILL GO
SLIGHTLY WARMER THAN FWC AND SLIGHTLY WETTER THAN MAV.
OTHERWISE...EXPECT TO GO NEAR MEX TEMPS DAYS 3-7...SLIGHTLY HIGHER
THAN MEX POPS ON THU/SAT...AND SLIGHTLY LOWER ON FRI/SUN.

AGREE IN GENERAL WITH SPC SWODY1 FOR SEVERE THREAT. WILL AMPLIFY
THOUGH THAT RECENT MINI-SUPERCELL SPLIT OVER REAL COUNTY INDICATIVE
OF POTENTIAL THIS AFTERNOON FOR OUR SWRN AREA...GENERALLY SOUTH OF
I-10 WEST OF SAT AND WEST OF I-35 SOUTH OF SAT. ETA MODEL SOUNDINGS
INDICATE BRN AND 0-6KM SHEAR SUPPORTIVE OF SUPERCELLS IN THIS
AREA...ALONG WITH BEST FORCING FROM SWD PROGRESSING 50-70KT JET
STREAK...NOSE OF -10C 500 MB TEMPS...AND BEST SFC HEATING. WILL
HIGHLIGHT THIS AREA IN HWO...BUT KEEP MENTION OF SEVERE AREAWIDE.

THU IS LOOKING MORE AND MORE OMINOUS...AND NOT TO BE OUTDONE BY
POTENTIAL FOR STRONG TROPICAL WAVE SAT/SUN. WILL MAINTAIN HEAVY RAIN
MENTION IN ZFP AND HWO...BUT TOO EARLY FOR AN FFA. WILL KEEP SLIGHT
CHANCE POPS FOR NOW OVER THE WEEKEND...BUT TREND IS LOOKING LIKE
HIGHER POPS WILL BE NECESSARY IF TROPICAL WAVE PLAYS OUT.

TXZ171>173-183>194-202>209-217>225-228-131100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
600 AM CDT TUE AUG 12 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL TEXAS.

.DAY ONE...TODAY.
ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND
EVENING ACROSS PARTS OF SOUTH CENTRAL TEXAS AND THE HILL COUNTRY.
THE MAIN AREA OF CONCERN IS WEST OF A LINE FROM MOUNTAIN HOME TO SAN
ANTONIO TO PEARSALL AND CATARINA. ANOTHER UPPER LEVEL DISTURBANCE
LOCATED OVER THE ARKLATEX WILL DRIFT SOUTHWEST TODAY APPROACHING THE
REGION THIS AFTERNOON. THIS UPPER LEVEL FEATURE WILL COMBINE WITH
DAYTIME HEATING TO TRIGGER ISOLATED SEVERE THUNDERSTORMS. THE
PRIMARY THREATS WILL BE DAMAGING WINDS AND LARGE HAIL.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.
THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE
REMAINDER OF THE WEEK AND EXTEND INTO THE WEEKEND. THE BEST CHANCE
OF SHOWERS AND THUNDERSTORMS WILL BE ON THURSDAY WHEN DEEP TROPICAL
MOISTURE OVERSPREADS THE REGION.  HEAVY RAINFALL AND POSSIBLE FLASH
FLOODING WILL BE THE PRIMARY THREATS FOR THURSDAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT ANTICIPATED.

PRELIMINARY LOCAL STORM REPORT...COR FOR DATE AND TIME
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO, TX
1014 AM CDT TUE AUG 12 2003

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

328 PM     RANDOLPH AFB              TX   62 MPH TSTM WIND GUST
08/11/03   BEXAR                          REPORTED BY AIR FORCE
                                          PERSONNEL.

805 PM     PARMER LANE               TX   WIND DAMAGE
08/11/03   AUSTIN                         UPROOTED TREES WITH TRUNKS
                                          OF ONE FOOT IN
                                          DIAMETER.REPORTED
                                          BY RESIDENT.

810 PM     PARMER LANE               TX   1.00 INCH HAIL
08/11/03   AUSTIN                         REPORTED BY RESIDENT.

KW