Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 300516 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1216 AM CDT SAT MAY 30 2015

.DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

&&

.AVIATION...VFR CONDITIONS NOW WITH LIGHT SOUTHEAST WINDS. CLOUD
COVER SHOULD REMAIN FEW TO SCT TONIGHT...WITH PERHAPS SOME TEMPO
MVFR NEAR DAWN. BACKED OFF ON INHERITED THICKER LOW CLOUD COVER
FOR THE NIGHT. SATELLITE SHOWS A FEW HIGH CLOUDS IN THE MIX TOO.
GUIDANCE SUGGESTS MODERATE SOUTHEAST WINDS DURING THE DAY WITH FEW
TO SCT LOW CLOUDS EARLY BECOMING BKN LATE MORNING TO EARLY AFTN
WITH CIGS ABOVE 3 KFT. A BROAD HIGH PRESSURE PATTERN WILL BE IN
PLAY...BUT A FRONT OVER WEST TEXAS MAY TRIGGER BIG BEND CONVECTION
SATURDAY NIGHT ALONG WITH MORE ACTIVITY OVER THE MEXICAN MNTNS.
THESE SHOULD NOT AFFECT LOCAL TAFS...BUT ARE MENTIONED FOR
COMPLETENESS.

&&

.PREV DISCUSSION... /ISSUED 855 PM CDT FRI MAY 29 2015/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...IR SATL IMAGERY SHOWS SOME MID AND HIGH LEVEL CLD
COVER ADVECTING FROM WEST TO EAST HEADING TOWARDS DEEP SOUTH TX
FROM THE CONV FIRING OVER NORTH CENTRAL MEXICO. THESE AREAS WILL
PUSH OVER THE RGV AIRPORTS OVER THE NEXT SEVERAL HOURS. THE NAM
FORECAST SOUNDINGS INDICATE THAT A FAIRLY LOW BASED SATURATED
LAYER WILL FORM LATER TONIGHT LIKELY REDUCING THE CEILINGS DOWN TO
MVFR/IFR LEVELS. THIS SATURATED DECK SHOULD MIX OUT TOMORROW WITH
THE INCREASING DAYTIME HEATING ALLOWING FOR A RETURN OF VFR
CONDITIONS.

PREV DISCUSSION... /ISSUED 358 PM CDT FRI MAY 29 2015/

SHORT TERM /NOW THROUGH SATURDAY NIGHT/...MESO LOW MOVING ACROSS NE
TX PUSHED THROUGH A STRONG LINE OF THUNDERSTORMS ACROSS THE CWA THIS
MORNING. A MUCH DRIER AND STABLE AIR MASS HAS MOVED BEHIND THIS LOW
ALLOWING FOR CLEAR SKIES AND WARM REST OF THE DAY. CURRENTLY...THE
LINE OF STORMS IS FURTHER SE INTO THE GULF BUT AN MCV DEVELOP NEAR
THE LOWER TEXAS COAST INCREASING SOUTHEAST WINDS WITH GUSTY WINDS
NEAR THE COASTAL AREAS. DUE TO THE CLEAR SKIES...WARM TEMPERATURES
WILL BE NEAR 90 DEGREES WEST OF HIGHWAY 77 AND NEAR 93 DEGREES NEAR
ZAPATA COUNTY.

TONIGHT...UPPER LOW SHIFTS FURTHER EAST WITH A WESTERLY FLOW SETTING
UP ALOFT. THE SOUTHEAST FLOW WILL MAINTAIN LOW LEVEL MOISTURE ACROSS
THE AREA RETURNING LOW LEVEL CLOUDS ALONG THE INVERSION TONIGHT. DUE
TO THE RAINFALL TODAY AND ABUNDANCE OF MOISTURE IN THE SATURATED SOIL
.THE POTENTIAL FOR PATCHY FOG IS POSSIBLE. EXPECT THE LIGHTER WINDS
TO DEVELOP CLOSER TO MIDNIGHT FROM THE SE FEEDING LOW LEVEL MOISTURE
INLAND. EXPECT VISIBILITY TO REDUCE WITH THE FOG AND BKN TO OVC LOW
CEILINGS. LOW TEMPERATURES WILL BE IN THE MID 70S ACROSS THE CWA AND
NEAR 80S ALONG THE COAST.

SATURDAY...WEAK RIDGE BEGINS TO BUILD WITH A MORE NORTHWESTERLY FLOW
ALOFT WITH SLIGHTLY DRY AIR IN THE AREA. SOUTHEASTERLY FLOW NEAR THE
SURFACE WILL KEEP A MODERATE SOUTHEAST FLOW WITH CU BUILDING DURING
THE DAY. PRECIPITABLE WATER BEGIN TO INCREASE TO 1.5 TO 1.7 INCHES
WHILE A FRONTAL BOUNDARY MOVES SOUTHWARD ACROSS SOUTHWEST TEXAS. THE
WINDS BEGIN TO SHIFT MORE EASTERLY AS THE FRONT REMAINS TO THE NORTH.
A LINE OF THUNDERSTORMS WILL DEVELOP AHEAD OF THIS BOUNDARY AND WILL
LIKELY MAKE IT TO OUR AREA BY THE EVENING AND NIGHT HOURS SATURDAY.
LEAN TOWARDS HIGHER POPS BY THE END OF SATURDAY INTO EARLY SUNDAY
WHEN THE MAIN BOUNDARY MOVES CLOSER TO THE AREA. HIGH TEMPERATURES
ON SATURDAY WILL BE RANGING FROM MID TO UPPER 80S NEAR THE COAST AND
NEAR 90S TOWARDS THE WEST.

LONG TERM /SUNDAY THROUGH FRIDAY/...THE GLOBAL MODELS CONTINUE
TO BE IN GOOD AGREEMENT WITH THE 500MB TROUGH MOVING THROUGH THE
SOUTHERN PLAINS SAT NIGHT INTO SUNDAY BUT TODAY THE GFS AND THE
ECMWF BEGIN TO DIVERGE WITH THE EVOLUTION OF THE UPPER LEVEL
TROUGH ACROSS THE SOUTHEAST UNITED STATES MONDAY INTO TUESDAY. THE
GFS CONTINUES TO DEVELOP A CUT-OFF 500MB LOW ACROSS LOUISIANA
MONDAY AS THE TROUGH LIFTS NORTHEAST ACROSS THE EASTERN U.S. AND
RETROGRADES THE LOW SLOWLY WESTWARD ACROSS THE UPPER TEXAS COAST
TUESDAY WHILE THE ECMWF HAS THE TROUGH MOVING SLOWLY EASTWARD
ACROSS THE EASTERN U.S. WITH A 500MB RIDGE BUILDING ACROSS THE
SOUTHERN PLAINS MONDAY INTO TUESDAY. SUBSIDENCE SHOULD INCREASE
ACROSS SOUTH TX BY THE MIDDLE OF NEXT WEEK REGARDLESS OF THE
DIFFERENCES IN THE GLOBAL MODELS. AT THE SURFACE...A WEAK COLD
FRONT IS EXPECTED TO MOVE THROUGH SOUTH TX AND MOVE INTO THE
NORTHWEST GULF OF MEXICO SAT NIGHT INTO SUNDAY. THIS WILL PROVIDE
A CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE CWA AS LOW TO MID
LEVEL MOISTURE POOLS ACROSS NORTHEAST MEXICO ITO SOUTH TX. SOME
DRIER AIR IS EXPECTED TO FILTER INTO THE AREA MONDAY AS WEAK
SURFACE HIGH PRESSURE BUILDS INTO EAST TX. THE SURFACE RIDGE WILL
MOVE EASTWARD TUESDAY INTO WEDNESDAY AS A SURFACE TROUGH DEVELOPS
ACROSS NORTHWEST TX. RAIN CHANCES SHOULD DIMINISH MONDAY BUT A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH
THE WEEK AS ISOLATED SEABREEZE CONVECTION DEVELOPS ACROSS THE
COASTAL SECTIONS AND MOVES INLAND DURING THE AFTERNOON HOURS.

MARINE...
NOW THROUGH SATURDAY NIGHT...AN MCV OVER THE GULF OF
MEXICO IS KEEPING A STRONG EASTERLY FLOW FOR THE REMAINDER OF THE
AFTERNOON IMPROVING IN THE EARLY EVENING. A SCA IS IN EFFECT DUE
TO THE STRONG WINDS ASSOCIATED WITH THIS LOW. TONIGHT CONDITIONS
IMPROVE WITH SE FLOW ACROSS THE AREA AND LOW SEAS. INTO SATURDAY
NIGHT...A BOUNDARY MOVING ACROSS THE NORTH CENTRAL TEXAS WILL GET
CLOSER TO THE GULF INCREASING THE CHANCE OF SHOWERS AND
THUNDERSTORMS. SEAS WILL REMAIN BETWEEN 4 TO 5 FEET WITH MODERATE
WINDS.

SUNDAY THROUGH WEDNESDAY...LIGHT NORTHEAST WINDS WILL PREVAIL
ACROSS THE COASTAL WATERS SUNDAY WITH WEAK SURFACE HIGH PRESSURE
BUILDING INTO THE NORTHWEST GULF OF MEXICO IN THE WAKE OF A WEAK
COLD FRONT MOVING INTO THE WESTERN GULF SAT NIGHT. LIGHT AND
VARIABLE WINDS WILL PREVAIL ACROSS THE COASTAL WATERS MONDAY AS
THE PRESSURE GRADIENT REMAINS WEAK ACROSS THE WESTERN GULF. LIGHT
SOUTHEAST WINDS SHOULD PREVAIL ACROSS THE LOWER TEXAS COAST
TUESDAY AND WEDNESDAY AS A SURFACE TROUGH OF LOW PRESSURE MOVES
INTO NORTHWEST TEXAS.

HYDROLOGY...THE RIO GRANDE NEAR SAN BENITO (SBNT2) WAS NEAR 51 FEET
THIS AFTERNOON AND APPEARS TO HAVE CRESTED NEAR 52 FEET. THE RIVER
STAGE FOR SBNT2 IS EXPECTED TO REMAIN NEAR 51 FEET THE NEXT
COUPLE OF DAYS. FLOOD STAGE FOR SBNT2 IS 55 FEET. AT 55
FEET...MINOR LOWLAND FLOODING REACHES INTO THE LOWEST SECTIONS OF
THE FLOOD PLAIN INSIDE THE LEVEES WITH NO SIGNIFICANT DAMAGE. THE
RIO GRANDE AT LOWER BROWNSVILLE (LOBT2) WAS NEAR 21 FEET THIS
AFTERNOON AND IS EXPECTED TO CREST NEAR 24 FEET LATE SUNDAY NIGHT.
FLOOD STAGE FOR LOBT2 IS 27 FEET. AT 24 FEET...THE RIVER EXCEEDS
THE LOWEST SECTIONS OF THE BANKS INSIDE THE LEVEES. THESE RIVER
FORECASTS FOR THE LOWER RIO GRANDE ARE BASED ON THE CURRENT AND
EXPECTED RELEASES FROM THE MARTE GOMEZ RESERVOIR IN MEXICO.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

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