Flash Flood Warning 31, NWS Brownsville, TX

DEEP SOUTH TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
915 AM CDT SAT SEP 20 2003

TODAY THRU MON...SFC OBS SHOW COASTAL TROF NEAR LAGUNA...WITH
CONVERGENT FLOW CONTINUING TOWARD THE LOWER TX COAST FROM THE
WESTERN GULF. OLD BNDRY TO NE IS HELPING CONVERGE MOISTURE AS WELL.
RIGHT ENTRANCE REGION DYNAMICS ARE SUGGESTED BY GFS INITIAL H5
FIELDS/WV IMAGERY. 88D/IR SAT IMAGERY SHOW A MID LEVEL CIRCULATION
CENTER JUST TO THE SOUTH OF SAN FERNANDO SLOWLY LIFTING NORTHWARD.
MODELS SEEM TO GRAB ON TO THIS FEATURE AND CONTINUE TO SLOWLY LIFT
IT OUT TO THE NORTH...THEN NORTHEASTWARD ON MONDAY. SURGE OF
MOISTURE IS MOVING UP THE TAMAULIPAS COAST AHEAD OF THE CIRCULATION
CENTER...WITH CONVECTION DEVELOPING ON THE LEADING EDGE OF THE
SURGE. MODELS ALL AGREE ON KEEPING DEEP TROPICAL MOISTURE AND
CONVERGENT SFC FLOW IN PLACE THROUGH MIDDAY SUNDAY...THEN LIFT
DEVELOPING SFC LOW TO THE NE OF THE CWA SUN PM. HOWEVER...VWP SHOWS
DEPTH OF EASTERLY FLOW TO ONLY 16K FT...VERSUS 25K FT WEATERDAY.
THIS MAY SUPPRESS/FOCUS CONVECTION TOWARD/OFF THE COAST. MESOETA
SHUTS OFF ACCESS TO GULF MOISTURE BY 00Z MON...WITH GFS PERSISTENT
IN POOLING MOISTURE ALONG TRAILING BNDRY BEHIND THE SFC LOW. BELIEVE
CURRENT ZFP IS CONSISTENT WITH THIS SCENARIO VIA LIKELY/CATEGORICAL
POPS THRU SUN PM...TAPERING TO CHANCE ON MON. NO CHANGES NEEDED.
STILL BELIEVE A FLASH FLOOD WATCH WILL BE NECESSARY THRU SUN PM.
WILL REASSESS THIS AFTERNOON.

TUE THRU FRI...TUE LOOKS DRIER WITH SOME LINGERING SHRA ALONG THE
IMMEDIATE COAST AND OFFSHORE POSSIBLE AS SFC LOW PULLS OUT TO THE NE
IN GFS. REINFORCING COLD FRONT NO LONGER APPEARS EVIDENT IN GFS
SURFACE FIELDS. SLIGHT CHANCE POPS LOOK GOOD FOR REST OF THE
WEEK...AS MEX GUIDANCE/GFS FCST FIELDS SUGGEST SOME MOISTURE MAY
BACK IN FROM THE SE ALONG WITH REMAINS OF BNDRY PROGGED TO PUSH SE
SUN. CURRENT ZFP COVERS THIS WELL...NO CHANGES ANTICIPATED.

MARINE...AT 8 AM BOY020 REPORTED EAST WINDS AT 8 KNOTS WITH GUSTS TO
10 KNOTS AND 4 FT SEAS WITH 7 SEC PERIOD. A SURFACE TROUGH LOCATED
ALONG THE GULF COAST OF DEEP SOUTH TEXAS AND NORTHEAST MEXICO ALONG
WITH A MOIST ATMOSPHERE WILL GENERATE SHOWERS AND A FEW
THUNDERSTORMS OVER THE MARINE AREAS OF DEEP SOUTH TEXAS TODAY.
BROWNSVILLE DOPPLER RADAR IS DETECTING SHOWERS OFFSHORE THIS
MORNING. SCATTERED TO NUMEROUS SHOWERS ARE LOCATED IN NORTHEAST
MEXICO AND OFF THE NORTHEAST MEXICAN COAST. THE SHOWERS ARE MOVING
AND DEVELOPING NORTHWARD INTO THE MARINE AND COASTAL AREAS OF DEEP
SOUTH TEXAS.  EXPECT SCATTERED TO NUMEROUS SHOWERS AND A FEW
THUNDERSTORMS TO CONTINUE TO DEVELOP AND MOVE OVER THE MARINE AREAS
THROUGH THIS EVENING. EXPECT LIGHT TO MODERATE EASTERLY WINDS
VARIABLE AT TIMES IN CONVECTION. WILL GO WITH SMALL CRAFT SHOULD
EXERCISE CAUTION OFFSHORE TODAY.

AVIATION...VFR CONDITIONS WITH PERIODS OF MVFR AND IFR CEILINGS AND
VISBILITIES ARE EXPECTED OVER THE REGIONAL AIRPORTS OF DEEP SOUTH
TEXAS THE NEXT 24 HOURS. SCATTERED TO NUMEROUS SHOWERS AND A FEW
THUNDERSTORMS WILL FIRE TODAY. LIGHT TO MODERATE EASTERLY WINDS WILL
BE VARIABLE AT TIMES NEAR CONVECTION. GUSTY WINDS AND OCCASIONAL
LIGHTNING STRIKES WILL OCCUR WITH AN ISOLATED THUNDERSTORM.

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE        TT 081/074 081/074 085 100/80/100/70/30
HARLINGEN          TT 080/073 082/073 085 100/80/100/60/30
MCALLEN            TT 082/074 082/072 086 100/70/80/50/30
RIO GRANDE CITY    TT 082/073 083/071 087 100/70/70/50/20
SOUTH PADRE ISLAND TT 080/076 081/076 083 100/80/100/80/30

.BRO...FFA FOR ALL OF DEEP SOUTH TEXAS UNTIL 5 PM TODAY.

SYNOPTIC...62
MARINE/AVIATION...63
MESO...VEGA

THIS PRODUCT IS ALSO AVAILABLE ON OUR INTERNET WEB PAGE AT:
HTTP://WWW.SRH.NOAA.GOV/BRO

TXZ248>257-202200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BROWNSVILLE TX
500 AM CDT SAT SEP 20 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR DEEP SOUTH TEXAS.

.DAY ONE...TODAY AND TONIGHT.

A FLASH FLOOD WATCH IS IN EFFECT FOR ALL OF DEEP SOUTH TEXAS THROUGH
5 PM THIS AFTERNOON. SHOWERS AND THUNDERSTORMS WILL LIKELY REDEVELOP
ACROSS MOST OF DEEP SOUTH TEXAS TODAY...DUE TO THE INTERACTION OF A
MOIST AND UNSTABLE AIR MASS AND A NEARLY STATIONARY FRONT OVER THE
LOWER TEXAS COAST. THE GREATEST WEATHER HAZARD WILL BE WIDESPREAD
HEAVY RAINFALL AND FLOODING OF LOW LYING AREAS AND ROADWAYS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

THE CHANCES OF LOCALLY HEAVY RAINFALL AND FLOODING WILL CONTINUE
THROUGH MONDAY FROM SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS
EXPECTED THROUGH THIS PERIOD. THE SHOWER AND THUNDERSTORM ACTIVITY
WILL BE FURTHER ENHANCED BY ANOTHER COLD FRONT WHICH IS EXPECTED TO
MOVE SOUTH OF DEEP SOUTH TEXAS BY TUESDAY. PARTLY CLOUDY SKIES
AND REDUCED RAIN CHANCES ARE EXPECTED FROM WEDNESDAY THROUGH FRIDAY
AS DRIER...COOLER AND MORE STABLE AIR BUILDS INTO PLACE IN THE WAKE
OF THE COLD FRONT.

.SPOTTER INFORMATION STATEMENT.

SPOTTER ACTIVATION MAY BE NECESSARY TODAY AND TONIGHT DUE TO THE
FLOODING THREAT.

SPEECE