Severe Thunderstorm Warning 99, NWS San Angelo, TX

WEST CENTRAL TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
200 PM CDT WED MAY 30 2001

PER LATEST MESOSCALE ANALYSIS AND LOCAL WARNING RADARS...COLD FRONT
EXTENDED FROM STERLING CITY AND SWEETWATER...TO HASKELL AND
THROCKMORTON AT 18Z. PER MSAS 3 HR PRES CHANGE...FRONT PULLING UP
STATIONARY. AIR MASS IN VICINITY EXTREMELY UNSTABLE WITH LIFTED
INDICES TO MINUS 10...AND GOES SATELLITE BASED CAPES IN EXCESS OF
5000 J/KG. PER WATER VAPOR IMAGERY...SHORTWAVE TROUGH EMBEDDED IN
NORTHWEST FLOW EVIDENT OVER CENTRAL COLORADO.

MESOETA THE MODEL OF CHOICE...SIMPLY DUE TO BETTER RESOLUTION OF LOW
LEVEL FEATURES AND TIMING OF APPROACHING SHORTWAVE TROUGH. PRESENT
INDICATIONS SUGGEST CAP WILL ERODE NEAR THE STALLED FRONT LATE THIS
AFTERNOON AND EARLY THIS EVENING...ALLOWING FOR EXPLOSIVE
THUNDERSTORM DEVELOPMENT. SPC HAS UPGRADED PORTIONS OF THE BIG
COUNTRY INTO THE MODERATE CATEGORY. EVENTUALLY...A TRANSITION TOWARD
AN MCS IS EXPECTED LATE THIS EVENING AND OVERNIGHT AS THE SHORTWAVE
TROUGH CATCHES UP TO THE SOUTHWARD SINKING COLD FRONT. SO FOR THE
REMAINDER OF WEST CENTRAL TEXAS...EXPECT SOME MUCH NEEDED RAINFALL
AND STRONG GUSTY WINDS...PERHAPS REACHING SEVERE LIMITS.

DEEP MOISTURE HAS BEEN PROBLEMATIC OF LATE. APPEARS THIS WILL NOT BE
THE CASE TONIGHT AS PRECIPITABLE WATER VALUES CLIMB TO NEAR 2.00
INCHES. SO UNLIKE THE HIGH BASED SPRINKLES OF LATE...GULLY WASHERS A
GOOD BET WITH AMOUNTS APPROACHING TWO INCHES LOCALLY.

THE ATMOSPHERE WILL REMAIN MOIST AND UNSTABLE ON THURSDAY...WITH
RESIDUAL BOUNDARIES PROVIDING THE FOCUS. 20 POPS PLANNED ACROSS THE
BOARD. AIR MASS BECOMES CAPPED THURSDAY NIGHT AND FRIDAY. AVN HINTS
AT ANOTHER MCS FRIDAY NIGHT...BUT WE/LL NOT MENTION AS MID LEVEL
TEMPERATURES REMAIN RATHER WARM.

PRELIM CCF...

ABI 065/083/063/087  7210
SJT 067/085/062/090  5210
JCT 069/082/064/088  5210

.SJT...NONE.(

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TXZ049-054-064>066-071>073-076>078-098-099-113-114-127-128-139-140-
154-155-168>170-311000-

WEST CENTRAL TEXAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN ANGELO TX
1247 PM CDT WED MAY 30 2001

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
PORTIONS OF THE BIG COUNTRY LATE THIS AFTERNOON AND EVENING...

A COLD FRONT CURRENTLY OVER THE TEXAS AND OKLAHOMA PANHANDLES WILL
CONTINUE TO SLOWLY MOVE SOUTHWARD THROUGH THE DAY. AS AN UPPER LEVEL
DISTURBANCE PHASES WITH THE LOWER LEVEL BOUNDARY BY THIS
EVENING...SUFFICIENT LIFT WILL BE IN PLACE OVER WEST CENTRAL TEXAS.
BY LATE THIS AFTERNOON...AS TEMPERATURES CLIMB AND SOUTHERLY WIND
SPEEDS IN THE LOW LEVELS INCREASE...A MOIST AND VERY UNSTABLE AIRMASS
WILL EXIST.

GIVEN THE DEGREE OF INSTABILITY AND WIND SHEAR...THERE IS A SLIGHT
RISK OF SEVERE THUNDERSTORMS WITH DAMAGING WINDS...SOME LARGE
HAIL...AND ISOLATED TORNADOES...PRIMARILY ALONG AND TO THE NORTH OF A
SAN ANGELO TO BROWNWOOD LINE. GIVEN THE EXPECTED PROXIMITY OF THE
FRONTAL BOUNDARY AND THE BETTER UPPER LEVEL SUPPORT...AN EVEN GREATER
MODERATE RISK OF SEVERE WEATHER WILL EXIST OVER THAT PORTION OF WEST
CENTRAL TEXAS ALONG AND TO THE NORTH OF AN ANSON TO ALBANY LINE.

THUNDERSTORMS WILL LIKELY BEGIN TO DEVELOP BY 4 PM OR 5 PM THIS
AFTERNOON ACROSS NORTHERN AND WESTERN PORTIONS OF THE BIG COUNTRY.
THIS ACTIVITY WILL SPREAD TO THE SOUTH DURING THE EVENING AND WILL
LIKELY REACH THE CONCHO VALLEY BETWEEN 10 PM AND MIDNIGHT. AFTER 2
AM...THE THREAT OF SEVERE WEATHER WILL BEGIN TO DIMINISH AS MORE IN
THE WAY OF A WIDESPREAD RAIN EVENT EVOLVES. IN FACT...WITH THE
INCREASED MOISTURE TRANSPORT THAT IS EXPECTED INTO THE AREA
TONIGHT...VERY HEAVY RAINFALL WILL BE LIKELY WITH LOCALIZED RAINFALL
AMOUNTS OF 1 TO 2 INCHES POSSIBLE.

SPOTTER ACTIVATION WILL LIKELY BE REQUIRED.

FOR THE SOUTHWEST TEXAS AND SOUTHEAST NEW MEXICO OUTLOOK SEE PRODUCT
LBBSPSMAF. FOR THE SOUTH PLAINS OUTLOOK SEE PRODUCT LBBSPSLBB. FOR
THE CENTRAL OKLAHOMA OUTLOOK SEE PRODUCT OKCSPSOKC. FOR THE NORTH
TEXAS OUTLOOK SEE PRODUCT FTWSPSFTW. FOR THE SOUTH CENTRAL TEXAS
OUTLOOK SEE PRODUCT SATSPSSAT.

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