Severe Thunderstorm Warning 146, NWS Austin/San Antonio, TX

SOUTH CENTRAL TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
955 AM CST MON DEC 30 2002

STRONG SOUTHEAST FLOW PUMPING MOISTURE OVER SOUTH CENTRAL TEXAS WITH
GUSTS OVER 30 MPH.  BREAKS IN CLOUD COVER CENTRAL ZONES WILL AID
DESTABILIZATION.  WITH UPR JET ALREADY PUSHING ACROSS THE RIO GRANDE
AND MID LEVEL JET PROGGED TO ENTER CWA EARLY AFTERNOON EXPECT
COMPONENTS OF SEVERE WEATHER OUTBREAK TO COME TOGETHER QUICKLY WITH
RATHER EXPLOSIVE DEVELOPMENT AS PRE-FRONTAL TROF...STRONG SOUTHEAST
INFLOW...AND MID/UPR LEVEL JET STRUCTURES MEET OVER SOUTH CENTRAL
TEXAS. CAPES NEAR 1200 NOW WILL CLIMB WITH SOME HEATING...AREAS IN
MEXICO CURRENTLY INDICATING NEAR 3000 J/KG.  HELICITIES BASED ON
MESOETA 300-350.  CAN EXPECT SOME ADDITIONAL VEERING ESPECIALLY IN
ISOLATED CELLS AHEAD OF MAIN LINE.

FRONT SHOULD BLOW THROUGH BY 00Z WEST AND 03Z EAST WITH LINGERING
CLOUD COVER GONE BY SUNRISE.  BRIEF CONCERN WITH ELEVATED CONVECTION
UNTIL CLOSED LOW FINALLY MOVES EAST BY 12Z.
10/18/VL

PREVIOUS DISCUSSION:
SEVERE WEATHER EVENT SHAPING UP FOR MOST OF THE EWX CWA TODAY AND
THIS EVENING, THEN CHAMBER OF COMMERCE WEATHER THE REMAINDER OF THE
FORECAST CYCLE.  GENERALLY FOLLOWED THE ETA IN THE SURFACE TO 850 MB
LAYER WITH GFS ABOVE AS THIS SEEMS THE BETTER WAY TO GO LATELY.

MID LEVEL TROUGH IN EASTERN ARIZONA WILL DROP A LITTLE FURTHER SOUTH
AND DEEPEN ON STRONG UPPER JET STILL ON BACK SIDE THIS MORNING, THEN
TRACK ACROSS CENTRAL TEXAS THIS EVENING.  PACIFIC COLD FRONT WILL
MOVE ACROSS CWA LATE THIS MORNING AND AFTERNOON.  INITIALLY, A STRONG
CAP WITH ONLY SHOWERS ON THE LOW LEVEL JET, THEN AS DAYTIME HEATING
PUSHES TEMPERATURES INTO THE 70S, RAPID DESTABILIZATION,
STRENGTHENING UPPER DIFFLUENCE, AND WEAKENING CAP ALLOW DEEPER
CONVECTION TO DEVELOP OVER THE WESTERN HILL COUNTRY AND FORM INTO A
SQUALL LINE BY THE I-35/HIGHWAY 281 CORRIDOR AND THEN TRACK EAST.
DAMAGING WINDS, TORNADOES, AND LARGE HAIL CAN BE EXPECTED WITH THE
LINE ON CAPES 2200 TO 2800, LIS -8 TO -10, AND KS 34 TO 37.  PWS OF
1 TO 1.5 INCHES ON PLUME OF MOISTURE FROM SOUTHWEST OF HAWAII ALSO
SUGGESTS LOCALLY HEAVY RAINS.  BEHIND SQUALL LINE, UNTIL AROUND
MIDNIGHT, AS THE LOW MOVES ACROSS, DEEP CONVECTION TO REDEVELOP ON
FURTHER DESTABILIZATION AS LOWER LEVELS DRY OUT ONLY A LITTLE.  LARGE
HAIL CAN BE EXPECTED WITH THE LOW ON STEEP MID LEVEL LAPSE RATES.
SQUALL LINE SHOULD BE ACTIVE FOR THE NEXT FEW DAYS AS IT MOVES ACROSS
THE SOUTHEASTERN STATES, GULF OF MEXICO AND OUT INTO THE ATLANTIC.

BRIEF RIDGING LATE TONIGHT AND TUESDAY MAKE FOR MOSTLY CLEAR SKIES.
ANOTHER SHORT-WAVE MOVES THE THROUGH PLAINS ON WEDNESDAY (NEW YEARS
DAY) WITH CYCLONIC FLOW ALOFT MAKING FOR PARTLY CLOUDY SKIES, AND
DRAGGING ANOTHER COLD FRONT ACROSS THE CWA BY EVENING, ALTHOUGH NO
POPS AS MOISTURE AND LIFT LACKING.  NORTHWEST FLOW DUE TROUGH OVER
THE EASTERN STATES AND SURFACE RIDGE BUILDS INTO TEXAS FOR MOSTLY
CLEAR SKIES THURSDAY AND FRIDAY.  OVER THE WEEKEND,  ANOTHER SHORT-
WAVE MOVES ACROSS THE PLAINS TO REINFORCE THE EASTERN TROUGH AND
DRAG ANOTHER COLD FRONT INTO THE CWA.  AGAIN MOISTURE AND LIFT
LACKING FOR POPS.

DAILY TEMPERATURES WILL AVERAGE NEAR SEASONAL LEVELS WITH SOME DAY TO
DAY VARIATION, EXCEPT WELL ABOVE AVERAGE TODAY.

PRELIMS...
AUS TA 075/043 064/033 068 85000
DRT NU 074/035 070/040 070 20000
SAT TU 075/045 066/036 070 74000

.EWX...NONE.

TXZ171>173-183>194-202>209-217>225-228-311200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
550 AM CST MON DEC 30 2002

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL TEXAS.

.DAY ONE...
A POTENT UPPER LEVEL LOW AND ASSOCIATED COLD FRONT NEAR EL PASO WILL
PROGRESS SOUTHEAST TODAY AND INTERACT WITH MOISTURE FROM THE GULF OF
MEXICO TO PRODUCE NUMEROUS THUNDERSTORMS OVER SOUTH CENTRAL TEXAS.
CHANCES FOR THUNDERSTORMS WILL BE GREATEST ALONG AND EAST OF
INTERSTATE 35 BETWEEN SAN ANTONIO AND AUSTIN. THESE STORMS WILL
LIKELY BECOME SEVERE...PRODUCING LARGE HAIL AND DAMAGING WINDS.
ISOLATED TORNADOES WILL BE POSSIBLE AS WELL. THE GREATEST THREAT FOR
SEVERE THUNDERSTORMS WILL BE ALONG THE COLD FRONT THIS AFTERNOON.

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

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL LIKELY BE NEEDED ACROSS THE EASTERN HALF OF
SOUTH CENTRAL TEXAS TODAY.