Severe Thunderstorm Warning 17, NWS Austin/San Antonio, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
1222 PM CDT TUE MAR 13 2007

.AVIATION...
THUNDERSTORMS HAVE BEGUN TO DEVELOP ACROSS SOUTH CENTRAL TEXAS.
THESE STORMS ARE EXPECTED TO INCREASE IN COVERAGE AS THEY MOVE
NORTHEAST ACROSS THE REGION. PREVAILING VFR WITH PATCHY MVFR/IFR
CONDITIONS ARE EXPECTED TO DETERIORATE ALONG THE I-35 CORRIDOR AS
THE STORMS APPROACH TAF SITES. THESE STORMS ARE EXPECTED TO BE
WIDESPREAD BY 21Z AND WILL CONTINUE ACROSS THE AREA UNTIL AT LEAST
03Z WEDNESDAY.

&&

.PREV DISCUSSION... /ISSUED 1012 AM CDT TUE MAR 13 2007/

DISCUSSION...
CONTINUED GOOD CHANCE OF RAIN EXPECTED THROUGH WEDNESDAY
MORNING...WITH LOCALLY HEAVY RAIN STILL POSSIBLE.  WILL
KEEP FLASH FLOOD WATCH THRU 7 AM WEDNESDAY MORNING.
LOW ALOFT NEAR THE SE CORNER OF NEW MEXICO IS FORECAST
TO MOVE EAST ACROSS TEXAS TONIGHT AND WEDNESDAY MORNING.
AHEAD OF THIS MARCH RAIN MAKER...OCCASIONAL RAIN WILL
CONTINUE FORMING TODAY AND TONIGHT...WITH SHOWERS AND
THUNDERSTORMS. THIS AREA OF RAIN WILL SLOWLY MOVE EAST
LATER TODAY AND TONIGHT...THRU WEDNESDAY MORNING...AS
THE LOW ALOFT IS CARRIED EAST. BY WEDNESDAY AFTERNOON A
COMPOSITE OF SOLUTIONS SINCE THE WEEKEND SHOWS THE LOW
MOVING EAST OF THE AREA...SIGNALING DECREASING CLOUDS
AND RAIN CHANCES FROM THE WEST BEGINNING WEDNESDAY MORNING
AND CONTINUING THRU WEDNESDAY AFTERNOON.

MORE STABLE CONDITIONS EVOLVING QUICKLY FROM THE WEST
WEDNESDAY NIGHT AND THURSDAY MORNING. THIS MAY HELP
PATCHY FOG FORM OVER PART OF THE AREA THURSDAY MORNING...
THEN MIXING OUT TO A MOSTLY SUNNY AND WARM DAY THURSDAY...
AHEAD OF A COLD FRONT FORECAST TO MOVE ACROSS THE AREA ON
THURSDAY NIGHT THROUGH FRIDAY. INITIALLY CLOUDS MAY COME
WITH THE COLD FRONT AND AN ASSOCIATED S/W TROF COMING
FROM THE N AND NW. CLEARING EXPECTED IN THE DAY FRIDAY
AND FRIDAY NIGHT IN WAKE OF THIS PROGRESSIVE MOVING
WEATHER SYSTEM. A MOSTLY SUNNY TO PARTLY CLOUDY DAY
IS EXPECTED SATURDAY.  INCREASING CLOUDS ARE EXPECTED
SATURDAY NIGHT THROUGH MONDAY...AS SOUTHERLY WINDS
RETURN AND INCREASE.

MEDIUM RANGE TOOLS SHOW ANOTHER WINDOW FOR RAIN OPENING
UP IN THE WEEK OF MAR 19 TO MAR 24. ONE WINDOW COULD COME
WITH A WEAK COOL FRONT IN THE MIDDLE OF NEXT WEEK AND
ANOTHER WINDOW FOR RAIN SHOWS UP LATE NEXT WEEK TO THE
WEEKEND OF MARCH 24 AND 25...AS A 500 HPA LOW IS FORECAST
TO APPROACH THE AREA FROM THE WEST.

PREV DISCUSSION... /ISSUED 350 AM CDT TUE MAR 13 2007/

DISCUSSION...LARGE UPPER LEVEL LOW PRESSURE IS QUASI-STATIONARY
OVER THE WEST TEXAS/NEW MEXICO BORDER THIS MORNING. LOOKING AT THE
WATER VAPOR IMAGERY THIS FEATURE IS QUITE IMPRESSIVE. THIS SYSTEM
WILL BEGIN TO TRACK EASTWARD TODAY AND TONIGHT ACROSS TEXAS.
CURRENTLY ON RADAR...THERE ARE SHOWERS AND THUNDERSTORMS IN OUR
NORTHEASTERN COUNTIES. THESE SHOWERS AND THUNDERSTORMS HAVE BEEN
PROPOGATING...REFORMING...AND TRAINING OVERNIGHT. THE UPPER RAIN
AMOUNTS OVERNIGHT...ACCORDING TO RADAR ESTIMATION...ARE AROUND 3
INCHES IN WILSON AND GONZALES COUNTIES.

AS THE UPPER LOW PROGRESSES EASTWARD TODAY AND TONIGHT...MANY
SHORTWAVES WILL ROTATE AROUND THE UPPER LOW...CONTINUING TO BRING
WAVES OF SHOWERS AND THUNDERSTORMS TO THE REGION. PW AMOUNTS ARE
RUNNING VERY SIMILAR TO YESTERDAY MORNING...WITH 0.84 INCHES AT
KDRT AND 1.53 INCHES AT KCRP. AMPLE MOISTURE IS IN PLACE ALONG
WITH AMPLE LIFT FROM THE UPPER LOW. THEREFORE FLASH FLOODING IS A
THREAT FOR THE NEXT 24 HOURS...AT LEAST. WE WILL ISSUE A FLASH
FLOOD WATCH FOR THE EASTERN HALF OF OUR CWFA. IN CONJUNCTION WITH
THE THREAT TO FLASH FLOODING...WE ALSO HAVE A SLIGHT RISK FOR
SEVERE THUNDERSTORMS FOR TODAY AS WELL.

THE UPPER LOW WILL FINALLY MAKE ITS EXIT OUT OF TEXAS LATE WEDNESDAY.
THIS WILL BRING AN END TO THE RAIN CHANCES BY WEDNESDAY EVENING
FOR SOUTH CENTRAL TEXAS. SKIES WILL CLEAR BEHIND THE SYSTEM AND
WINDS WILL BE CALM WEDNESDAY NIGHT. DUE TO SATURATED
GROUNDS...THIS WILL BE THE PERFECT SET UP FOR FOG. SO HAVE
INCLUDED FOG IN THE FORECAST LATE WEDNESDAY NIGHT/THURSDAY
MORNING. A COLD/DRY FRONT IS FORECAST TO MOVE THROUGH THE AREA
SOMETIME THURSDAY NIGHT...ALTHOUGH THE MODELS DIFFER IN THEIR
SOLUTIONS. HAVE GONE MORE WITH A CONSENSUS FORECAST AND BROUGHT
THE FRONT THROUGH THE REGION...ALONG THE LINES OF THE NAM12 AND
ECMWF. THIS WILL MEAN WARM TEMPERATURES AHEAD OF THE FRONT ON
THURSDAY...THEN COOLER TEMPERATURES ON FRIDAY POST FROPA. AFTER
THE FRONTAL PASSAGE...TEMPERATURES WILL BE CLOSER TO SEASONAL
NORMALS FOR THE REMAINDER OF THE FORECAST PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY              63  79  59  84  56 /  80  50  -    0  -
AUSTIN BERGSTROM INTL AIRPORT  60  78  55  81  52 /  80  50  -    0  -
DEL RIO INTL AIRPORT           60  86  59  89  61 /  30  10  -   -   -
SAN ANTONIO INTL AIRPORT       63  81  61  85  58 /  70  40  -    0  -

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH THROUGH WEDNESDAY MORNING FOR THE FOLLOWING
ZONES: ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...BURNET...
CALDWELL...COMAL...DE WITT...FAYETTE...FRIO...GILLESPIE...
GONZALES...GUADALUPE...HAYS...KARNES...KENDALL...KERR...LAVACA...
LEE...LLANO...MEDINA...TRAVIS...WILLIAMSON...WILSON.

&&

08/25

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
537 AM CDT TUE MAR 13 2007

TXZ171>173-183>194-202>209-217>225-228-141100-
LLANO-BURNET-WILLIAMSON-VAL VERDE-EDWARDS-REAL-KERR-BANDERA-
GILLESPIE-KENDALL-BLANCO-HAYS-TRAVIS-BASTROP-LEE-KINNEY-UVALDE-
MEDINA-BEXAR-COMAL-GUADALUPE-CALDWELL-FAYETTE-MAVERICK-ZAVALA-
FRIO-ATASCOSA-WILSON-KARNES-GONZALES-DE WITT-LAVACA-DIMMIT-
537 AM CDT TUE MAR 13 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL TEXAS.

.DAY ONE...TODAY AND TONIGHT
THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS TODAY AND TONIGHT
ACROSS ALL OF SOUTH CENTRAL TEXAS...WITH LARGE HAIL AND DAMAGING
WINDS BEING THE PRIMARY THREATS. A FLASH FLOOD WATCH IS IN EFFECT
FOR THE EASTERN TWO-THIRDS OF SOUTH CENTRAL TEXAS THROUGH TONIGHT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE NEEDED TODAY.