Flash Flood Warning 55, NWS Brownsville, TX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
300 PM CDT TUE OCT 5 2004

.SHORT TERM...CONV HAS NOW FIRED UP OVER THE WESTERN PORTIONS OF THE
BRO CWA WHERE AFTERNOON HEATING IS ENHANCING INSTABILITY AND LOW
LEVEL CONVERGENCE ALONG AN OLD OUTFLOW BOUNDARY THAT HAS PUSHED INTO
THE BRO CWA FROM THE NE. MEANWHILE TO THE SOUTH AND SOUTHEAST OF
BRO...IR SATL IMAGERY SHOWS A DECENT COVERAGE OF CONV OVER THE SW
GULF OF MEX IN ASSOCIATION WITH THE TROPICAL WAVE IN THIS REGION.
SATL TRENDS AND MODEL MEAN RH FIELDS SHOW THE ASSOCIATED TROPICAL
MOISTURE CONTINUING TO ADVECT NORTHWARDS ALONG THE TX COASTLINE OVER
THE NEXT COUPLE OF DAYS.  BOTH THE GFS AND ETA CONTINUE TO DIG A
MAJOR 5H TROUGH AXIS OVER THE SOUTHERN ROCKIES AND THE SOUTH CENTRAL
PLAINS STATES THROUGH WED AND EARLY THURS WITH NUMEROUS POCKETS OF
VORTICITY ADVECTING NE AHEAD OF THE OVERALL TROUGH AXIS WHICH WILL
CONTINUE TO PROVIDE GOOD UVV IN THE SHORT TERM.  THE BIG DIFFERENCE
BETWEEN THE TWO MODELS CONCERNS THE DIFFERENCE IN THE SURFACE LOW
REFLECTION IN THE GFS AND THE ETA.  THE GFS HAS BEEN CONSISTENT IN
FORMING A COASTAL TROUGH/LOW ALONG THE TX COASTLINE LATER IN THE
FORECAST PERIOD WHILE THE ETA IS NOT SHOWING MUCH OF A SURFACE
FEATURE HERE.  THE ECMWF AND THE UKMET ARE FAVORING THE GFS SOLUTION
SO WITH THE ETA BEING THE OUTLIER WILL GO WITH GFS.  WITH THE
ANTICIPATED FORMATION OF THE COASTAL LOW...THE BETTER CHCS FOR HVY
RAINS WILL LIKELY SHIFT TOWARDS THE COASTAL AREAS OF THE BRO CWA WED
AND THURS AS THE GFS ALSO SHOWS PCPN BEING ENHANCED BY A PRETTY
STRONG 250 MB JET MAX FORMING OVER THE COASTLINE IN THE 48 TO 60 HR
RANGE.  CONSIDERING THE BETTER AGREEMENT IN THE SURFACE FEATURES
SHOWN IN THE GFS/UKMET/ECMWF COMBO ATTM TEND TO FAVOR THE HIGHER MAV
RAIN CHCS AS OPPOSED TO THE LOWER MET GUIDANCE.  OVERALL TEMPERATURE
GUIDANCE BETWEEN THE MAV AND MET GUIDANCE IS IN REASONABLE AGREEMENT
AND ANTICIPATE NO MAJOR CHANGES HERE.  CONSIDERING THAT THE
COMPONENTS APPEAR TO BE ON TRACK FOR A MAJOR RAIN EVENT ACROSS THE
BRO CWA OVER THE NEXT SEVERAL DAYS WILL POST AN FFA FOR FLASH
FLOODING THIS AFTERNOON FOR THE ENTIRE BRO CWA.
&&

.LONG TERM...THE RAIN POTENTIAL BEGINS TO TAPER OFF TOWARDS THE
UPCOMING WEEKEND AS THE MUCH ANTICIPATED COASTAL LOW LIFTS TO THE NE
AND THE 5H TROUGH AXIS ALSO SHIFTS TOWARDS THE TX/LA COASTLINE BY
12Z SUN AND WESTERN WINDS AT THE 5H LEVEL WILL SHIFT THE TROPICAL
MOISTURE PLUME FURTHER EAST OVER THE GULF OF MEXICO.  WILL LIKELY
KEEP THE RAIN CHCS ON INTO FRIDAY NIGHT AND WILL THEN TAPER THEM OFF
FOR SAT AND SUN. WILL GO WITH TEMPS NEAR CLIMO FOR THE EXTENDED
PERIOD.
&&

.MARINE...AT 1PM BUOY020 REPORTED EASTERLY WINDS AT 15KTS AND SEAS 4
FEET. OUTFLOW BOUNDARIES APPROACHING THE COASTAL WATERS FROM THE
NORTH AND SOUTH TRANSLATE TO A WET AFTERNOON. MARINERS CAN EXPECT
BRIEF HEAVY DOWNPOURS...OCCASIONAL LIGHTNING AND INCREASED SEAS NEAR
THUNDERSTORMS. OTHERWISE...WINDS SHOULD REMAIN FROM THE EAST THROUGH
THE NEXT COUPLE DAYS WITH HIGH PRESSURE TO THE NORTHEAST. WITH A
LONG FETCH OF EAST WINDS, WAVE HEIGHTS WILL RISE TO PEAK AT 6 TO 7
FEET ON THURSDAY. THIS MAY BE INHIBITED A BIT LATE WEEK BY A
POSSIBLE COASTAL TROUGH. SHOWER AND THUNDERSTORM ACTIVITY WILL
REMAIN IN THE FORECAST INTO THE WEEKEND DUE TO A TROPICAL WAVE IN
THE BAY OF CAMPECHE AND A MIDLEVEL SYSTEM MOVING THROUGH CENTRAL
TEXAS.
&&

.AVIATION...SHOWER AND THUNDERSTORM ACTIVITY HAS BEGUN TO DEVELOP IN
DEEP SOUTH TEXAS AS MULTITUDES OF OUTFLOW BOUNDARIES CONVERGE ON THE
REGION. AVIATORS CAN EXPECT PERIODS OF REDUCED CIGS AND VIS AND
OCCASIONAL LIGHTNING AS THE THUNDERSTORMS APPROACH REGIONAL
AIRPORTS. THUNDERSTORM ACTIVITY IS EXPECTED TO LET UP SOME TONIGHT
BUT NOT COMPLETELY.
&&

.BRO WATCHES/WARNINGS/ADVISORIES...FLASH FLOOD WATCH IN EFFECT UNTIL
4 PM WED FOR TXZ248>257.
&&

SYNOPTIC/GRIDS...60
MARINE/AVIATION...64
MESO...MARTINEZ

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BROWNSVILLE TX
600 AM CDT TUE OCT 5 2004

TXZ248>257-061100-
BROOKS-COASTAL CAMERON-COASTAL WILLACY-HIDALGO-INLAND CAMERON-
INLAND WILLACY-JIM HOGG-KENEDY-STARR-ZAPATA-
600 AM CDT TUE OCT 5 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR DEEP SOUTH TEXAS.

.DAY ONE...TODAY AND TONIGHT.

A SURFACE LOW PRESSURE TROUGH WILL COMBINE WITH DEEP TROPICAL
MOISTURE OVER DEEP SOUTH TEXAS ALLOWING SCATTERED SHOWERS
TO CONTINUE TODAY. SOME OF THESE THUNDERSTORMS MAY PRODUCE WIND GUSTS
TO 30 MPH...OCCASIONAL LIGHTNING AND BRIEF HEAVY RAINS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

THE SURFACE TROUGH ALONG THE LOWER TEXAS COAST WILL CREATE A GOOD
CHANCE FOR SHOWERS AND THUNDERSTORMS THROUGH THE END OF THIS WEEK.
THESE SHOWERS AND THUNDERSTORMS MAY PRODUCE LOCALLY HEAVY RAINS...
BRIEF WIND GUSTS OF 30 MPH AND FREQUENT LIGHTNING. SEAS MAY BECOME
QUITE ACTIVE ALONG THE WEST GULF COAST AS SWELLS ARE GENERATED BY A
BROAD AREA OF EAST WINDS OVER NEARLY ALL OF THE SOUTHERN AND CENTRAL
GULF OF MEXICO. TIDES ARE RUNNING ALMOST 2 FEET ABOVE MEAN LOWER LOW
WATER AND THE STRONG WAVE ACTION MAY MAGNIFY THE TIDAL EFFECTS
BY THE END OF THE WEEK. FLOOD HAZARDS PRESENTED BY VERY HEAVY
RAINFALL ARE POSSIBLE...ESPECIALLY WEDNESDAY AND THURSDAY. ALSO...THE
RISKS OF DANGEROUS RIP CURRENTS WILL INCREASE WEDNESDAY AND
THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED.

CAFFREY