Flash Flood and Hail in Texas, October 10 to 11, 2001

WEST CENTRAL TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN ANGELO TX
201 AM CDT WED OCT 10 2001

DECENT SHOT OF RAIN SHAPING UP FOR WC TX LATE THIS EVENING. SURFACE
DEWPOINTS WERE IN THE UPPER 60S OVER ALL OF WC TX. METARS AND GOES
IR IMAGERY SHOWS A WESTWARD RETREATING DRYLINE FROM FAR W TX TO NEAR
KLBB. LATEST ETA RUN PLACES A STRONGER CAP WITH RESPECT TO THE
BOUNDARY LAYER OVER WC TX THIS AFTERNOON. SOME CONCERN THAT THIS MAY
BE INFLUENCED BY SUSPECT DEWPOINT DATA IN THE 00Z CRP SOUNDING.
HOWEVER...LOW LEVEL MASS CONVERGENCE APPEARS LACKING OVER THE
SOUTHEAST HALF OF WC TX TODAY...AND WILL REDUCE FIRST PERIOD POPS IN
THESE AREAS.

06Z SURFACE MAP SHOWS A COLD FRON FROM THE N TX PANHANDLE TO CENTRAL
KS. ETA PROGS THIS FEATURE TO DROP INTO THE NORTHERN BIG COUNTRY
ZONES LATE THIS AFTERNOON...AND THE CONCHO VALLEY AROUND MIDNIGHT.
LOWER ATMOSPHERE OVER WC TX WILL DESTABILIZE AHEAD OF AN APPROACHING
UPPER TROF OVER NM LATE WED EVENING. ETA SHOWS RATHER STRONG MASS
CONVERGENCE NEAR THE 850 MB FRONT OVER THE BIG COUNTRY/CONCHO VALLEY
FROM 06Z-12Z. SOME CONCERN FOR HEAVY RAIN...AS MID LEVEL STEERING
FLOW WILL BE ROUGHLY PARALLEL TO THE SLOW MOVING FRONT AND DIVERGENT
THICKNESS FIELD HINT AT THE POSSIBILITY OF BACKBUILDING STORMS. BIG
COUNTRY AND HEARTLAND ZONES WILL ALSO BE UNDER THE RIGHT ENTRANCE
REGION OF A 250 MB JET MAX. WITH THESE CONSIDERATIONS IN MIND...
WILL MENTION LOCALLY HEAVY RAINFALL FOR TONIGHT.

POST-SUNRISE SHOWERS POSSIBLE OVER WC TX THURSDAY...AS UPPER TROF
CENTER TRACKS EAST ACROSS WC TX. EXPECT LOW CLOUDS TO CLEAR BY MID
TO LATE AFTERNOON...AS 850 MB THERMAL TROF LIFTS EAST.

AVN/ETA ARE IN GOOD AGREEMENT AT 60 HOURS REGARDING A VIGOROUS UPPER
TROF DIVING INTO THE 4-CORNERS AREA. AVN STRENGTHENS THIS FEATURE AS
IT BRINGS IT TO THE PERMIAN BASIN/SOUTH PLAINS BY FRIDAY EVENING.
IMPRESSIVE DYNAMICS WILL LIKELY HAVE LESS MOISTURE TO WORK WITH THAN
DID PREVIOUS SYSTEMS. CHANCE POPS IN PREVIOUS FORECAST APPEAR ON
TARGET FOR FRIDAY.

DRY NORTHWEST FLOW ALOFT EXPECTED FROM SATURDAY INTO EARLY NEXT
WEEK. NO CHANGES PLANNED FOR THE EXTENDED.

PRELIM CCF...
ABI 081/057/074/058 3520
SJT 082/059/075/057 2520
JCT 081/065/076/056 1420

.SJT...NONE.

14

TXZ049-054-064>066-071>073-076>078-098-099-113-114-127-128-139-140-
154-155-168>170-101500-

WEST CENTRAL TEXAS HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN ANGELO TX
545 AM CDT WED OCT 10 2001

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING ACROSS ALL OF WEST CENTRAL TEXAS...

ABUNDANT LOW LEVEL MOISTURE REMAINS IN PLACE ACROSS WEST CENTRAL
TEXAS WITH EARLY MORNING DEWPOINTS IN THE UPPER 60S.

THE ATMOSPHERE WILL BECOME INCREASINGLY UNSTABLE THIS AFTERNOON DUE
TO DAYTIME HEATING AND THE PRESENCE OF ABUNDANT LOW LEVEL MOISTURE.
MEANWHILE...A COLD FRONT WILL ENTER THE BIG COUNTRY LATE THIS
AFTERNOON AND PROGRESS SLOWLY SOUTH ACROSS WEST CENTRAL TEXAS
TONIGHT.

SCATTERED THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON ALONG THE
COLD FRONT. THUNDERSTORMS WILL INCREASE IN COVERAGE DURING THE
EVENING AS THE FRONT MOVES SLOWLY SOUTH. ADEQUATE INSTABILITY AND
WIND SHEAR MAY HELP PRODUCE A FEW SEVERE THUNDERSTORMS THIS
AFTERNOON AND EVENING WITH THE MAIN THREATS BEING LARGE HAIL AND
DAMAGING WINDS.

ESPECIALLY DURING THE OVERNIGHT HOURS...SOME THUNDERSTORMS WILL
LIKELY PRODUCE LOCALLY HEAVY RAINFALL AS THEY MOVE PARALLEL TO THE
ORIENTATION OF THE COLD FRONT.

SPOTTER ACTIVATION MAY BE REQUIRED.

FOR THE SOUTHWEST TEXAS AND SOUTHEAST NEW MEXICO OUTLOOK SEE PRODUCT
LBBSPSMAF. FOR THE NORTH TEXAS OUTLOOK SEE PRODUCT FTWSPSFTW.

22/RUBIN