Severe Thunderstorm Warning 149, NWS San Angelo, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
308 PM CDT SAT SEP 23 2000

AS EXPECTED...COLD FRONT HAS JUST ABOUT PULLED UP STATIONARY FROM THE
NORTHERN PERMIAN BASIN TO JUST NORTH OF ABILENE TO ARDMORE OKLAHOMA. COLD
AIR JUST TOO SHALLOW TO MAKE MUCH HEADWAY INTO TEMPERATURES IN THE 90S.
COLD AIR MUCH DEEPER ACROSS THE PANHANDLE AND NORTHERN OKLAHOMA...WHERE LOW
CLOUDS HAVE HELPED KEEP TEMPERATURES IN THE LOW TO MID 50S. ALOFT...WATER
VAPOR IMAGERY CLEARLY SHOWS THE UPPER TROUGH DROPPING INTO THE GREAT
BASIN...HELPING KICK THE REMNANTS OF NORMAN ACROSS MEXICO AND INTO THE
SOUTHERN PLAINS.

FOR TONIGHT...AS THE UPPER TROUGH DROPS SOUTHEAST...SOUTHERLY FLOW IN THE
LOW LEVELS SHOULD INCREASE EVEN MORE. FRONT WILL WANT TO DRIFT BACK NORTH
OUT OF THE BIG COUNTRY...BUT IF ENOUGH CONVECTION FORMS NORTH OF THE FRONT
TO REINFORCE THE BOUNDARY...FRONT COULD ACTUALLY SHIFT SOUTHWARD. AT THIS
POINT...EXPECT THE FRONT TO REMAIN NEARLY STATIONARY...AS SOUTHERLY FLOW IS
OFFSET BY CONVECTION AND DENSITY OF COLDER AIR MASS. BY 12Z SUNDAY MORNING
...UPPER TROUGH MOVES CLOSE ENOUGH THAT THE COLD AIR FINALLY BEGINS TO
DEEPEN SIGNIFICANTLY...PUSHING THE FRONT QUICKLY SOUTHWARD. SIMILAR TO THE
FASTER ETA...THIS DRAGS THE FRONT THROUGH THE LAST FEW BIG COUNTRY COUNTIES
AROUND SUNRISE...INTO THE CENTRAL SECTIONS BY LATE MORNING...AND INTO THE
NORTHWEST HILL COUNTRY BY MID AFTERNOON.

RAIN CHANCES CONTINUE TO LOOK GOOD WITH THIS SYSTEM. CONVERGENCE WILL
CONTINUE ALONG THE FRONT...AND WITH THE MUGGY AIR MASS IN THE WARM SECTOR
...SHOULD SEE A FEW SHOWERS AND STORMS DEVELOP. HOWEVER...MOST OF THE
PRECIP WILL BE BEHIND THE FRONT WITH THE ISENTROPIC LIFT. WILL CARRY CHANCE
POPS ACROSS THE BIG COUNTRY TONIGHT...SPREADING SOUTHWARD ACROSS THE
REMAINDER OF THE WEST CENTRAL TEXAS ON SUNDAY. AS FOR TEMPS...NGM TOO SLOW
WITH THE FRONTAL MOVEMENT...SO WILL IGNORE IT.

IF THE SURFACE HIGH BUILDS INTO WEST CENTRAL TEXAS MONDAY NIGHT AS
FORECASTED...WILL LIKELY SEE THE COOLEST NIGHT SINCE THE END OF
APRIL...WITH LOWS DROPPING INTO THE 40S.

AS FOR THE EXTENDED...A FLAT UPPER RIDGE BUILDS BACK INTO THE SOUTHERN
PLAINS...ALLOWING A WARMING TREND TO BEGIN. STILL...WILL TAKE UNTIL FRIDAY
TO SEE VALUES CLIMB BACK TO NEAR NORMAL VALUES.

ABI 066/074/052/068 3520
SJT 074/086/055/068 2430
JCT 076/090/058/066 1451

.SJT...NONE.

07

TXZ049-054-064>066-071>073-076>078-098-099-113-114-127-128-139-
140-154-155-168>170-232330-

WEST CENTRAL TEXAS THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE SAN ANGELO TX
228 PM CDT SAT SEP 23 2000

...THERE IS A CHANCE OF NON SEVERE THUNDERSTORMS ACROSS NORTHERN AND
CENTRAL PORTIONS OF WEST CENTRAL TEXAS THROUGH TONIGHT...

THIS AFTERNOON...A STATIONARY BOUNDARY SEPARATING A MUCH COOLER
AIRMASS TO THE NORTH WAS POSITIONED ACROSS THE BIG COUNTRY ALONG A
LINE FROM FORT GRIFFIN TO SWEETWATER. THIS FRONT IS EXPECTED TO
REMAIN NEARLY STATIONARY THROUGH THIS EVENING BUT WILL BEGIN TO PUSH
SOUTHWARD AS A COLD FRONT LATE TONIGHT. DESPITE THIS AFTERNOONS CLOUD
COVER...ENOUGH HEATING ALONG AND TO THE SOUTH OF THE FRONT WILL
COMBINE WITH CONVERGENCE AND MOISTURE ALONG THE BOUNDARY TO PROVIDE A
CHANCE FOR THUNDERSTORMS ACROSS THE BIG COUNTRY THIS AFTERNOON AND
TONIGHT. AS THE FRONT BEGINS TO PUSH SLOWLY SOUTHWARD AFTER
MIDNIGHT...A SLIGHT CHANCE OF THUNDERSTORMS WILL THEN EXIST FOR THE
CONCHO VALLEY AND HEARTLAND AREAS AS WELL.

THE STRONGEST STORMS THAT DEVELOP WILL EFFECT THE BIG COUNTRY AREA OF
WEST CENTRAL TEXAS THIS EVENING. STORMS ARE NOT EXPECTED TO REACH
SEVERE LIMITS. HOWEVER...SMALL HAIL AND VERY HEAVY RAINFALL WILL BE
POSSIBLE. FURTHER SOUTH...ACROSS THE CONCHO VALLEY AND THE
HEARTLAND...THE SLIGHT RISK OF THUNDERSTORMS WILL BEGIN AFTER
MIDNIGHT. THESE STORMS...HOWEVER...SHOULD REMAIN WEAKER THAN THE
EVENING CONVECTION ACROSS THE BIG COUNTRY WITH SOME HEAVY RAINFALL
BEING THE EXTENT OF THE THUNDERSTORM THREAT.

SPOTTER ACTIVATION IS NOT ANTICIPATED..

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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