Flash Flooding in Texas, September 15, 2002

COASTAL BEND FORECAST DISCUSSION...UPDATED.
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
505 AM CDT SUN SEP 15 2002

** UPDATED TO ISSUE FLASH FLOOD WATCH ACROSS THE NORTHWEST CWA FROM
LASALLE COUNTY EASTWARD TO BEE COUNTY THROUGH MONDAY.  FRONTAL
BOUNDARY WHICH PUSHED OFF THE ESCARPMENT HAS STALLED OVER THE
NORTHWEST CWA AND EXPECT ABUNDANT MOISTURE CONVERGENCE AND TRAINING
TO OCCUR ACROSS THIS AREA.

DISCUSSION...CONVECTION DEVELOPING ACROSS MUCH OF THE WESTERN
FORECAST AREA EARLY THIS MORNING IN CONJUNCTION WITH INCREASING
PRECIPITABLE WATER VALUES ON THE VERTEX OF A WEAK SHORTWAVE MOVING
NORTHWARD FROM DEEP SOUTH TEXAS.  MESOETA DATA APPEARS TO BE AROUND
6 HOURS TOO SLOW WITH THE MOVEMENT OF THIS SHORTWAVE..HOWEVER GIVEN
THE CONVECTIVE DEVELOPMENT FARTHER TO THE SOUTH..IT APPEARS THE
CONVECTION TO THE WEST IS MOST LIKELY ASSOCIATED WITH MOISTURE
ADVECTION COLLIDING WITH A SUBTLE PRE-FRONTAL TROF OFF THE
ESCARPMENT PER MSAS STREAMLINE DATA.

SFC COLD FRONT BEST DEPICTED WITH THE POSITIVE ISALLOBARIC FIELD ON
MSAS WHICH ILLUSTRATES A SWATH OF 2-3 MB PRESSURE RISE COUPLETS FROM
THE BIG BEND NORTHEASTWARD TO MINERAL WELLS WITH THE SFC BOUNDARY
LOCATED SLIGHTLY TO THE EAST AND SOUTH ALONG A TYLER TO JUNCTION
LINE.  GIVEN THE PRESSURE RISES..THE FRONT WILL CONTINUE TO PUSH TO
THE SOUTH AND STALL IN THE SAN ANTONIO AREA THIS AFTERNOON.  AS A
RESULT..HIGH PWATS AND SUFFICIENT MOISTURE CONVERGENCE WILL BE
PRESENT OVER THE CWA TO GENERATE SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS.  EXPECT A BREAK IN COVERAGE DURING THE MID AFTERNOON
HOURS AS SFC MOISTURE CONVERGENT FIELDS ALIGN WITH ACTUAL FRONT TO
THE NORTH..WITH CONVECTION BECOMING MORE SCATTERED OVERNIGHT INTO
EARLY MONDAY.  OMEGA FIELDS AND INCREASING 850MB JET MONDAY NIGHT
SUGGESTS ADDITIONAL HEAVY RAINFALL..BEFORE MID-LEVEL TROF PASSES
LATER TUESDAY AND LOWERS THE MOISTURE DEPTH WHICH WILL DECREASE THE
POTENTIAL FOR CONVECTION THROUGH MUCH OF THE REMAINDER OF THE WEEK.

EXTENDED MODEL GUIDANCE CONTINUES THE TREND OF DELAYING UPCOMING
FRONTAL PASSAGES..WITH THE PREVIOUS FRIDAY FRONT NOW SCHEDULED FOR
SATURDAY.  GIVEN THE DECREASE IN MOISTURE DEPTH BEHIND THE PRESENT
SYSTEM..WILL FORECAST SLIGHT CHANCE OF DIURNAL CONVECTION ACROSS THE
EAST FOR WED WITH LIMITED MOISTURE FOR MENTION THU/FRI ACROSS THE
ENTIRE CWA.

MARINE...WIND FCST WILL BE A BIT TRICKY TODAY. MODELS PROG A WEAK TO
MOD E TO SE FLOW THRU MON...AS CF STALLS ACROSS S CENTRAL TX/N CWA
AND SFC LOW PREVAILS OVR W CWA. WINDS ALONG THE COAST HAVE SLIGHTLY
DIMINISHED...HOWEVER...FEEL WINDS COULD STRENGTHEN TODAY FEEDING
INTO CONVECTION ALONG STALLED FRONT. ALSO...OUTFLOW BDRIES IN THE
AREA WILL RESULT IN VRB WIND DIR. WILL GO WITH THE PREVAILING SE
WIND AROUND 15 KNOTS AND ADD MENTION OF WIND AND SEAS HIGHER NEAR
TSRAS. RADAR SHOWING DVLPMNT ALONG THE COAST THIS AM. WITH
INCREASING MOISTURE AND UPPER LEV VORT MAXS...TSRA ACTIVITY WILL BE
ON THE INCREASE ACROSS THE WATERS TODAY AND MON. SFC LOW TREKS NE BY
TUE WITH HIGH PRESS OVR THE NW GULF RESULTING IN WEAK TO MOD SLY
FLOW TUE THRU THU...AND DECREASING PRECIP AS WELL.

THE FORECAST NUMBERS ARE NEXT...
CRP TT 089/074 088/074 090 76566
VCT TT 089/072 087/072 089 76567
LRD TT 089/075 087/075 092 76676

BML.76 / TE.81

.CRP...FLASH FLOOD WATCH IN EFFECT TXZ229>232.

TXZ233-234-239>247-152100-

HEAVY RAINFALL OUTLOOK
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
505 AM CDT SUN SEP 15 2002

...HEAVY RAINFALL FORECAST ACROSS SOUTH TEXAS THROUGH EARLY
TUESDAY...

ABUNDANT MOISTURE STREAMING OVER SOUTH TEXAS WILL GENERATE SCATTERED
TO NUMEROUS SHOWERS AND THUNDERSTORMS AHEAD OF A COLD PUSHING TOWARD
THE AREA.

DUE TO THE HIGH MOISTURE CONTENT IN THE AIR...COMBINED WITH THE
CLOSE PROXIMITY OF THE COLD FRONT...HEAVY RAINFALL IS EXPECTED.

WIDESPREAD RAINFALL TOTALS RANGING BETWEEN 1 AND 2 INCHES WILL OCCUR
ACROSS THE AREA...WITH ISOLATED TOTALS RANGING BETWEEN 3 AND 4 INCHES
POSSIBLE.  THE ADDITIONAL RAINFALL WILL AGGRAVATE FLOODING ALONG THE
NUECES RIVER BASIN...AS WELL AS SURROUNDING RIVERS...CREEKS AND
STREAMS.

RESIDENTS ARE URGED TO STAY TUNED TO THE NATIONAL WEATHER SERVICE
FOR THE LATEST WEATHER INFORMATION.

LAMARRE