Severe Thunderstorm Warning 157, NWS San Angelo, TX

WEST CENTRAL TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
303 PM CDT WED OCT 25 2000

SHARP S/WV TROF AXIS PASSING ACROSS OUR CWFA THIS EVENING WITH STRONGEST
ENERGY PASSING TO OUR NORTH. DEEP MOISTURE CONTINUES TO SURGE NWRD ACROSS
W TX ON BRISK SLY LLVL WINDS AND 12Z DRT SOUNDING WAS INDICATIVE OF THE
AVAILABLE MOISTURE. THE ETA IS DEPICTING A NARROW BUT WELL PRONOUNCED LOW
LEVEL THETA E RIDGE SETTING UP JUST WEST OF OUR ZONES THIS EVENING WITH
STEERING WINDS JUST SOUTH OF WEST. SCT TSTMS WILL BE MOVING INTO THE WRN BIG
COUNTRY THIS AFTERNOON ACCORDING TO KSJT/KMAF WSR-88D RADARS. EXPECT TO SEE
A LINE OF NNE-SSW ORIENTED TSTMS DEVELOPING ALONG THE INDICATED INSTABILITY
AXIS THIS EVENING WHICH WILL THEN SWEEP EWRD ACROSS OUR ZONES WITH THE
GREATEST COVERAGE LIKELY ACROSS THE BIG COUNTRY AND LEAST IN THE SRN ZONES.
FORECASTED CAPES AND SHEAR VALUES SUGGEST THAT SOME STORMS MAY BE SEVERE AND
WILL INCLUDE MENTION IN THE ZONES AS PER SPC DY1 OUTLOOK.

A WEAKER S/WV FEATURE IS FORECAST BY THE ETA TO PASS ACROSS NE NM/W TX THU
AFTERNOON...ALTHOUGH IT IS LESS APPARENT ON THE AVN. WITH AVAILABLE MOISTURE
AND IMPRESSIVE LOW LEVEL THETA E RIDGE AXIS TO OUR WEST...WILL INSERT 20
PERCENT POPS FOR THE WRN BIG COUNTRY THU EVENING. S/WV RIDGING TAKES HOLD ON
FRI IN ADVANCE OF THE NEXT TROF APPROACHING FROM SRN CA. THETA-E AXIS MOVES
FURTHER WEST AND WITH THE ABSENCE OF LOW LEVEL FOCUSING MECHANISMS OR UPPER
LEVEL TRIGGERS...WILL LEAVE FRI DRY. LESS CLOUD COVER AND SLIGHTLY HIGHER
THICKNESSES SHOULD BOOST HIGHS A FEW DEGREES. THE MRF IS SHOWING GOOD
CONTINUITY FROM ITS PREVIOUS RUN WITH RESPECT TO THE SAT-MON EXTENDED
PERIOD...ALTHOUGH THE 72 HR AVN IS NOW SLOWER WITH THE TROF MOVEMENT THAN
THE 84 HR MRF. W TX WILL BE IN BETWEEN SYSTEMS SUN/MON SO WILL GO WITH A DRY
FORECAST WITH LITTLE CHANGE IN TEMPERATURES ANTICIPATED.

ABI 064/077/062/079 5020
SJT 065/078/063/080 30-0
JCT 065/077/065/078 2000

.SJT...NONE

22

TXZ049-054-064>066-071>073-076>078-098-099-113-114-127-128-139-
140-154-155-168>170-252220-

WEST CENTRAL TEXAS THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE SAN ANGELO TX
205 PM CDT WED OCT 25 2000

...THERE IS A SLIGHT CHANCE OF SEVERE THUNDERSTORMS ACROSS THE
CONCHO VALLEY AND BIG COUNTRY THROUGH THIS EVENING...

AN UPPER LEVEL DISTURBANCE MOVING NORTHEAST ACROSS NEW MEXICO WILL
COMBINE WITH A MOIST AND UNSTABLE AIR MASS TO GENERATE SCATTERED
THUNDERSTORMS ACROSS WEST CENTRAL TEXAS LATE THIS AFTERNOON AND
EVENING. GIVEN THE AMOUNT OF INSTABILITY PRESENT...A FEW OF THE
STORMS COULD STRENGTHEN TO SEVERE LEVELS...MOST LIKELY ALONG AND
NORTHWEST OF AN OZONA TO SAN ANGELO TO BAIRD LINE. ALTHOUGH THERE IS
ENOUGH WIND SHEAR IN THE ATMOSPHERE TO ALLOW AN ISOLATED TORNADO TO
DEVELOP...LARGE HAIL AND DAMAGING WINDS WILL BE THE PRIMARY THREATS.
IN ADDITION...ANY STORM THAT DOES DEVELOP WILL HAVE THE POTENTIAL OF
PRODUCING LOCALLY HEAVY RAINFALL...PERHAPS FLOODING LOW WATER
CROSSINGS AND OTHER POOR DRAINAGE AREAS.

WITH THE LOSS OF DAYTIME HEATING AFTER SUNSET AND WITH THE PASSAGE
OF THE UPPER LEVEL DISTURBANCE NORTH OF THE AREA LATE THIS EVENING...
THE THREAT OF SEVERE THUNDERSTORMS WILL DIMINISH.

SPOTTER ACTIVATION MAY 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 OUTLOlOK SEE PRODUCT OKCSPSOKC.
FOR THE NORTH TEXAS OUTLOOK SEE PRODUCT FTWSPSFTW. FOR THE SOUTH
CENTRAL TEXAS OUTLOOK SEE PRODUCT SATSPSSAT.

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