Severe Thunderstorm Warning 85, NWS San Angelo, TX

WEST CENTRAL TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
605 PM CDT THU MAY 24 2001

UPDATED ZONES TO REFLECT CURRENT SEVERE THUNDERSTORM WATCH FOR
SOUTHERN ZONES UNTIL 11 PM TONIGHT.

.SJT...SEVERE THUNDERSTORM WATCH TXZ076>078-169 UNTIL 11 PM.

HUBER

*********  312 PM CDT THU MAY 24 2001 DISCUSSION FOLLOWS *********

THE UPPER LEVEL LOW DOMINATING THE EASTERN TWO THIRDS OF THE
COUNTRY...  WILL MEANDER AROUND THE WESTERN GREAT LAKES REGION
THROUGH SATURDAY.  SEVERAL SHORTWAVES WILL ROTATE AROUND THE LOW IN
THE NORTHWEST FLOW PASSING ACROSS THE REGION. A COLD FRONT IS
CURRENTLY MAKING ITS WAY SOUTH ACROSS THE FORECAST AREA BUT IS
STARTING TO SLOW DOWN...ESPECIALLY ON THE WEST SIDE.

THIS EVENING...THE COLD FRONT WILL CONTINUE TO SLOWLY DRAG
SOUTH...WITH THE BEST MOVEMENT ACROSS THE EASTERN HALF OF THE
FORECAST AREA. 850-500MB RELATIVE HUMIDITY INCREASES TO 60 TO 70
PERCENT ACROSS THE SOUTHERN PORTIONS OF THE HEARTLAND AND THE
NORTHWEST HILL COUNTRY. THIS COMBINED WITH THE BEST INSTABILITY
TOWARDS THE SOUTHEAST THIS EVENING...WILL CONTINUE WITH THE CHANCE
OF AN ISOLATED THUNDERSTORM.

OVERNIGHT INTO FRIDAY THE NEXT SHORTWAVE MOVES ACROSS THE FORECAST
AREA.  THE BEST MOISTURE WILL BE ACROSS THE CONCHO VALLEY AND THE
HEARTLAND. THEREFORE WILL GO WITH THE BEST CHANCES FOR THESE AREAS
WITH LOWER CHANCE TO THE NORTH. BY AFTERNOON THE BOUNDARY LAYER
RELATIVE HUMIDITY INCREASES TO 60 TO 70 PERCENT SPREADING THROUGH
THE SOUTHERN COUNTIES. THE BEST INSTABILITY IS TO THE SOUTHWEST.
WITH LIS AT -4 TO -6 AND MID LEVEL LAPSE RATES INCREASING...AND A
SURFACE BOUNDARY CONTINUING TO LINGER IN THE AREA WILL CONTINUE
CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGHOUT THE DAY. ALSO WILL
NOT RULE OUT THE CHANCE OF A THUNDERSTORM APPROACHING SEVERE LIMITS
TO THE SOUTH.

FRIDAY NIGHT...SUFFICIENT MOISTURE AND DIURNAL HEATING WILL LINGER
INTO THE EVENING FOR THE SOUTHEAST COUNTIES. HOWEVER...AS THE
SHORTWAVE MOVES OFF TO THE SOUTHEAST...DRIER AIR MOVES IN FROM THE
NORTHWEST.

SATURDAY AND SATURDAY NIGHT...ANOTHER WEAK SHORTWAVE SLIDES SOUTH
ACROSS THE WESTERN COUNTIES. ALSO A DRY LINE DOES BEGIN TO DEVELOP
TO THE WEST OF THE FORECAST AREA...HOWEVER MOISTURE IS SEVERELY
LACKING THROUGHOUT THE COLUMN. THEREFORE WILL ONLY GO WITH PARTLY
CLOUDY.

IN THE EXTENDED...THE CUTOFF UPPER LOW CONTINUES TO MEANDER IN THE
OHIO VALLEY ON SUNDAY. ON MONDAY THE LOW FINALLY BEGINS TO GET
CAUGHT UP IN THE FLOW AND IS LIFTED OFF TO THE NORTHEAST...THE
BEGINNING OF NEXT WEEK. THIS WILL ALLOW A WEAK UPPER LEVEL RIDGE TO
BUILD INTO THE SOUTHERN PLAINS MONDAY AND TUESDAY...BEFORE AN UPPER
LEVEL TROUGH APPROACHES FROM THE WEST WEDNESDAY AND THURSDAY. HOW
QUICKLY THE LOW LIFTS TO THE NORTHEAST WILL HELP DETERMINE WHETHER
TO PUT THE CHANCE OF RAIN IN FOR LATE SUNDAY. THIS IS DUE TO A
SHORTWAVE BEING CURRENTLY PROGGED TO MOVE ACROSS THE PANHANDLE AND
OKLAHOMA...WITH THE SOUTHERN FRINGES CLIPPING THE BIG COUNTRY. FOR
NOW WILL HOLD OFF FROM INTRODUCING ANY MENTION OF PRECIPITATION. BY
MIDWEEK AS THE UPPER LOW APPROACHES A LOW LEVEL JET DEVELOPS AHEAD
OF THE ASSOCIATED SURFACE TROUGH. THIS WILL ALLOW MOISTURE TO RETURN
TO THE REGION...FROM THE SOUTH. THUS WILL LEAVE IN THE CHANCE OF
PRECIPITATION ON WEDNESDAY INTO THURSDAY.

ABI 053/078/060/082 12-0
SJT 055/080/059/085 23-0
JCT 059/081/059/086 12-0

.SJT...NONE.

24

TXZ049-054-064>066-071>073-076>078-098-099-113-114-127-128-139-140-
154-155-168>170-242300-

WEST CENTRAL TEXAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN ANGELO TX
220 PM CDT THU MAY 24 2001

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS LATE THIS
AFTERNOON AND EVENING...SOUTH OF A MERTZON...SAN ANGELO...SAN SABA
LINE.

A COLD FRONT HAS PUSHED SOUTH OF A METZON...SAN ANGELO... SAN SABA
LINE AT 2 PM. THE AIRMASS IS UNSTABLE ALONG AND SOUTH OF THE FRONT.
CONVERGENCE ALONG THE FRONT...COMBINED WITH SUFFICIENT VERTICAL WIND
SHEAR PROFILES WILL SUPPORT THE POSSIBILITY OF AN ISOLATED SEVERE
STORM LATE THIS AFTERNOON AND EARLY TONIGHT. THE MAIN SEVERE WEATHER
THREATS WILL BE LARGE HAIL AND DAMAGING WINDS.

ADDITIONAL STORMS WILL BE POSSIBLE AFTER MIDNIGHT...AS AN UPPER
LEVEL DISTURBANCE MOVE OVER THE REGION. THESE STORMS WILL BE MAINLY
SOUTH OF A STERLING CITY...BALLINGER....BROWNWOOD LINE. WITH ONLY
WEAK INSTABILITY...SEVERE STORMS ARE NOT EXPECTED WITH THESE LATE
NIGHT STORMS.

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 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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