Severe Thunderstorm Warning 83, NWS San Angelo, TX

WEST CENTRAL TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
215 PM CDT SAT MAY 3 2003

PRIMARY FORECASTS CONCERNS ARE THUNDERSTORM CHANCES THIS EVENING AND
SUNDAY AFTERNOON OVER THE EAST. 18Z SURFACE MAP SHOWS A DRYLINE
EXTENDING FROM THE NW TIP OF CROCKETT COUNTY...NORTHWARD INTO THE
SOUTH PLAINS...SW OF LUBBOCK. 19Z GOES VISIBLE IMAGERY SHOWS
DEVELOPING CU NEAR THE EXPECTED DRYLINE POSITION...EAST OF KFST.

15Z RUC PROGS THE DRYLINE TO MAKE LITTLE EASTWARD PROGRESS THIS
AFTERNOON...ALTHOUGH SOME DRIER MID LEVEL AIR IS PROGGED TO MIX TO
THE SURFACE OVER THE WESTERN CONCHO VALLEY AND WESTERN BIG COUNTRY.
12Z MESOETA BOUNDARY LAYER CAPE/CINH PROG IS IN LINE WITH THE 06Z
RUN IN DEVELOPING 3000+ J/KG BOUNDARY LAYER CAPE WITH NO CAP BY 21Z
OVER THE HEARTLAND AND EASTERN BIG COUNTRY. UNLIKE FRIDAY...12Z MAF
SOUNDING HAD MOISTURE IN THE LOWER LEVELS...WITH 17C DEWPOINTS UP TO
840MB. AS IT IS PRONE TO DO...THE MESOETA MAY BE MIXING THE DRYLINE
TOO FAR EAST THIS AFTERNOON. FOLLOWING RUC SOLUTION...AN ISOLATED
THUNDERSTORM OR TWO COULD DEVELOP AS FAR WEST AS THE SAN ANGELO AREA
LATER THIS AFTERNOON. 18Z FWD SOUNDING SHOWS WEAK CAPPING...WITH
EASILY REACHED CONVECTIVE TEMP INFERRED FOR OUR EASTERN BIG COUNTRY
COUNTIES.

ENTRANCE REGION OF LOW LEVEL JET WILL SET UP OVER WC TX TONIGHT...
WITH NO LARGE AREAS OF ORGANIZED MOISTURE CONVERGENCE EXPECTED. IN
RESPONSE TO A SHORTWAVE TROF PASSAGE SUNDAY AFTERNOON...THE MESOETA
BRINGS THE DRYLINE THROUGH MOST OF WC TX. AVN MAV GUIDANCE IN
AGREEMENT...WITH MID UPPER 40S DEWPOINTS AT KABI/KSJT AND MID 60S
DEWPOINTS AT KSJT. CURRENT ISC GRIDS INDICATE NO CHANCE OF
THUNDERSTORMS OVER THE HEARTLAND/NW HILL COUNTRY FOR SUNDAY...BUT WE
HAVE RESERVATIONS CONCERNING UNDERESTIMATED MESOETA BOUNDARY LATER
CAPE IN THE PRESENCE OF STRONG LOW LEVEL CONVERGENCE OVER EASTERN
PORTIONS OF THE FORECAST AREA. WILL LIKELY ADJUST GRIDS AND
MAINTAIN SLIGHT CHANCE POPS FROM THE PREVIOUS FORECAST OVER THE
HEARTLAND/NW HILL COUNTRY.

SHORTWAVE RIDGING ALOFT SHOULD KEEP A LID ON THUNDERSTORM
DEVELOPMENT MONDAY...BUT APPROACHING SHORTWAVE TROF SHOULD COOL MID
LEVEL TEMPS SUFFICIENTLY TO HELP STORMS FIRE OVER THE EAST ON
TUESDAY. PERSISTENCE APPEARS TO BE BEST FORECAST THROUGH LATE NEXT
WEEK... UNDER WEAK CONVECTIVE CAP.

ABI 071/093/063/088/061 22101
SJT 072/095/065/091/063 11101
JCT 070/090/064/092/062 22111

.SJT...NONE.

14

TXZ049-054-064>066-071>073-076>078-098-099-113-114-127-128-139-140-
154-155-168>170-041345-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN ANGELO TX
206 PM CDT SAT MAY 3 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WEST CENTRAL TEXAS.

.DAY ONE...

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTH OF A LINE FROM
SAN ANGELO TO SAN SABA. THIS AFTERNOON...A WARM FRONT WAS LOCATED
OVER HASKELL AND THROCKMORTON COUNTIES...WHILE THE DRYLINE WAS
CONTINUING TO GET BETTER ORGANIZED FROM NEAR LUBBOCK SOUTH TO ODESSA
TO NEAR FORT STOCKTON. MEANWHILE...THE LOW CLOUDS THAT WERE OVER THE
AREA THIS MORNING HAVE PRETTY MUCH ERODED ALLOWING SIGNIFICANT
HEATING TO TAKE OCCUR...AND WITH SUFFICIENT MOISTURE IN PLACE...THE
ATMOSPHERE IS BECOMING MORE UNSTABLE. WARMER TEMPERATURES ALOFT HAVE
RESULTED IN A CAP THAT WILL ACT TO PREVENT THUNDERSTORM DEVELOPMENT.
HOWEVER AS THE DRYLINE PUSHES EAST...AND AN UPPER LEVEL DISTURBANCE
APPROACHES THE AREA FROM NEW MEXICO...THE CAP MAY WEAKEN ENOUGH TO
ALLOW ISOLATED THUNDERSTORMS TO DEVELOP. THE BEST CHANCES OF THIS
OCCURRING IS OVER THE BIG COUNTRY. ALTHOUGH THUNDERSTORMS WILL BE
ISOLATED...THE STORMS THAT DO DEVELOP WILL BECOME RAPIDLY SEVERE AND
PRODUCE VERY LARGE HAIL AND DAMAGING WINDS. THERE WILL ALSO BE
SUFFICIENT WIND SHEAR FOR TORNADOES ALONG AND NORTH OF INTERSTATE
20. IF THE THUNDERSTORMS CAN GET GOING...THEY SHOULD BEGIN TO FORM
BETWEEN 4 AND 7 PM CDT.

.DAYS TWO THROUGH SEVEN...

A FEW THUNDERSTORMS WILL AGAIN BE POSSIBLE SUNDAY EVENING THROUGH
THE MIDDLE OF NEXT WEEK AS A FRONT INTERACTS WITH A MOIST AND
UNSTABLE AIRMASS.

.SPOTTER INFORMATION STATEMENT...

IF THUNDERSTORMS CAN BREAK THE CAP...SPOTTER ACTIVATION WILL BE
NEEDED...ESPECIALLY OVER THE BIG COUNTRY.

27/BRAZZELL