Flash Flood Warning 27, NWS Brownsville, TX

DEEP SOUTH TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
130 PM CDT SUN SEP 15 2002

.DISCUSSION...IR/WV SAT IMAGERY SUGGESTS H5 VORT MAX MOVING
NORTHWESTWAFD OUT OF MX HELPED TO TRIGGER OVERNITE SHRA/TSRA OVER
DEEP SOUTH TX. AT PRESENT...MUCH OF THIS CONVECTION HAD MOVED WELL
TO THE NORTHEAST OF THE CWA. 88D LOOP CONFIRMS THIS...AND SUGGESTS
WEAK SEA BREEZE CONVERGENCE BAND HAD ALREADY SET UP IN KENEDY
COUNTY. 88D/IR SAT IMAGERY...ALONG WITH 1218Z SCATTEROMETRY...SHOWS
TROPICAL WAVE IN THE BAY OF CAMPECHE. THIS FEATURE POSSESSES A LOT
OF RELATED CONVECTION. TROPICAL MOISTURE ASSOCIATED WITH THIS SYSTEM
APPEARS TO BE ADVECTING TOWARD THE CWA. ONE QUESTION TO ANSWER IS
WHETHER OR NOT SOME OF THIS MOISTURE WILL OVERSPREAD THE CWA LATER
TODAY. VAD WIND PROFILE CONTAINS DEEP LAYER SSE WINDS TO AT LEAST
13K FEET... SUGGESTING THIS IS POSSIBLE. 88D LOOP SHOWS SOME INBOUND
CONVECTION ABOUT 120 NM TO THE SOUTHEAST. SURFACE OBSERVATIONS AND
88D IMAGERY SHOW A BNDRY RUNNING FROM SOUTH OF BOY019 TO JUST SOUTH
OF MONTERREY. BNDRY APPEARS TO BE MOVING SLOWLY SOUTH...ESPECIALLY
ON ITS WESTERN FLANK. SFC OBS ALSO SHOW MESOHIGHLIKE FEATURE BEHIND
THIS BNDRY...SUGGESTING IT HAS OUTFLOW CHARACTERISTICS. BELIEVE COLD
FRONT IS FARTHER TO THE NORTHWEST...NEAR DRT...PER HPC ANALYSIS. AM
CONCERNED ABOUT THE POTENTIAL FOR FLASH FLOODING IN THE NORTHERN
COUNTIES IF THIS BNDRY HOLDS TOGETHER. THANX CRP FOR YOUR INPUTS AND
COORDINATION.

SHORT TERM...HAVE GONE WITH A FLASH FLOOD WATCH FOR THE 4
WESTERNMOST COUNTIES THRU 9 PM TODAY. AGREE WITH CRP THAT AVN HAS
BEST INITIAL HOLD ON H5 FEATURES...WITH MESOETA DOING BEST AT THE
SFC. WILL GO WITH HYBRID FCST APPROACH EMPHASIZING THESE TWO MODELS.
AVN BRINGS UP VORT MAX FROM THE SOUTH TOMORROW. MESOETA BRINGS
OUTFLOW BNDRY CURRENTLY BISECTING THE CWA TO THE COAST LATER
TODAY...THEN LETS IT RETREAT NW OVERNITE TOWARD THE STALLED COLD
FRONT NW OF THE CWA. ACCORDINGLY... WILL GO WITH HIGHEST POPS OUT
WEST TOMORROW. WILL GO WITH LIKELY CATEGORY ZONE WIDE TOMORROW. AS
H5 TROF AXIS WORKS EAST AND BOUNDARY TO THE N WEAKENS...SEA BREEZE
BECOMES PRIMARY FOCUS FOR CONVECTION. BELIEVE ENOUGH PWAT WILL
REMAIN FOR CHANCE POPS. AVN ACTUALLY MOVES THIS BNDRY SE AS H5 TROF
OPENS UP AND PULLS E...SO WILL FAVOR THE WETTER ETA MOS SOLUTION.

LONG TERM...WED LOOKS DRIER AS NW FLOW DEVELOPS OVER THE CWA BEHIND
THE DEPARTING H5 TROF...WILL GO WITH SLIGHT CHANCE POPS WITH
RESIDUAL MOISTURE FOCUSED BY THE SEA BREEZE BNDRY. THU AND FRI LOOK
DRY. STILL BELIEVE MRF IS TOO AGGRESSIVE WITH FRONT NEXT WEEKEND.
WILL GO WITH SLIGHT CHANCE POPS SAT...THEN CHANCE SUN AS MOISTURE
POOLS SOUTH OF THIS BNDRY.

MARINE...TROPICAL MOISTURE OVER DEEP SOUTH TEXAS WILL BE
REINFORCED LATER TODAY FROM A TROPICAL WAVE MOVING WEST
ACROSS THE BAY OF CAMPECHE...INCREASING RAIN CHANCES OVER THE COASTAL
WATERS TODAY AND MONDAY. IN ADDITION...SCATTERED SHOWERS AND
THUNDERSTORMS WILL CONTINUE TO DEVELOP AS A WEAK COLD FRONT MOVES
INTO CENTRAL TEXAS THIS AFTERNOON. AN OUTFLOW BNDRY WILL MOVE SE
OVER THE COASTAL WATERS TODAY...THEN BACK NORTH TONIGHT...CAUSING
SHIFTING WINDS. BOY020 HAS RECENTLY REPORTED A WIND SHIFT INTO THE
NW WITH THE OUTFLOW BNDRY...AND 3 FT SEAS. AFTER TONIGHT...A LIGHT
TO MODERATE ONSHORE FLOW WILL PERSIST THROUGH NEXT WEEK. NO FLAGS
EXPECTED.

.PRELIMINARY NUMBERS FOR COORDINATION PURPOSES ONLY...
BRO TE 077/092 077/091 077 30/60/30/40/40
HRL TE 076/091 076/093 076 30/60/30/40/40
MFE TT 077/090 077/094 077 40/70/40/50/40
RGC TT 075/089 075/095 075 50/80/50/50/30
SPI TE 078/086 078/087 078 30/50/30/30/40

SYNOPTIC...62
AVIATION-MARINE...59
MESO...WATKINS

INTERNET ADDRESS...WWW.SRH.NOAA.GOV/BRO

.BRO...NONE.