Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 011715 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1215 PM CDT TUE SEP 1 2015

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

.AVIATION...BACK TO A MORE TYPICAL SEA BREEZE-DRIVEN PATTERN
TODAY COMPARED TO MONDAY. ABUNDANT LOW LEVEL MOISTURE AND UNIFORM
EAST TO SOUTHEAST LOW LEVEL FLOW WILL LEAD TO SEA BREEZE FORMATION
AT THE COAST EARLY THIS AFTERNOON THAT WILL MOVE INLAND TOWARD THE
UPPER VALLEY BY MID AFTERNOON. WILL SEE ISOLD/SCT TS DEVELOP ALONG
THE SEA BREEZE WHICH WILL PROGRESS WESTWARD. TS LOOK TO MOSTLY END
BY 01Z THIS EVENING. SOUTH TO SOUTHEAST ONSHORE FLOW TO PERSIST
OVERNIGHT THROUGH WEDNESDAY MORNING.
&&

.PREV DISCUSSION... /ISSUED 642 AM CDT TUE SEP 1 2015/
DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...ATMOSPHERE HAS STABILIZED BEHIND EVENING AND OVERNIGHT
CONVECTION. HEATING WILL BE REQUIRED ALONG WITH THE SEABREEZE AND
REMNANT BOUNDARIES TO DEVELOP CONVECTION. HAVE DELAYED THE ONSET
AT OUR TAF SITES TO LATE MORNING AND AFTERNOON HOURS. THERE IS
SOME UNCERTAINTY ON COVERAGE AS HIGH RESOLUTION MODELS ARE ONLY
DEPICTING ISOLATED COVERAGE. OUTSIDE OF CONVECTION...EXPECT VFR
CONDITIONS WITH ESE WINDS BECOMING GUSTY LATE MORNING AND
AFTERNOON HOURS.

PREV DISCUSSION... /ISSUED 339 AM CDT TUE SEP 1 2015/

SHORT TERM /NOW THROUGH WEDNESDAY/...EARLY MORNING WATER VAPOR
SHOWS TROUGH AXIS DRAPED ACROSS THE CENTRAL CWA EXTENDING NORTHEAST
INTO EASTERN TEXAS. DIFFLUENCE IS NOTED MOSTLY ACROSS THE WESTERN
GULF WATERS AND THIS IS WHERE THE BETTER LARGE SCALE LIFT IS
LOCATED. SHOWERS AND THUNDERSTORMS HAVE REALLY BLOSSOMED ACROSS THIS
AREA OVER THE PAST FEW HOURS AND IS AIDED BY 2.2 INCH PWAT PER
BLENDED TPW PRODUCTS. WITH THE SHEER AMOUNT OF COVERAGE HAVE
BUMPED POPS UP SHOWING NUMEROUS COVERAGE ACROSS THE GULF WATERS
THIS MORNING WITH HEAVY RAINFALL AND GUSTY WINDS. NOT MUCH
CONVECTION HAS INFILTRATED THE COASTAL COUNTIES AS OF YET BUT DID
RAISE POPS SOME FOR THE IMMEDIATE COAST EARLY THIS MORNING BUT AM
EXPECTING SOME IN THE NEXT FEW HOURS AS OUTFLOWS POSSIBLY PULL
CONVECTION ONSHORE. 0- 6KM MEAN WIND IS VIRTUALLY DUE SOUTH SO
MOST CONVECTION WILL REMAIN OVER THE COASTAL WATERS.

HAVE ADDED HEAVY RAINFALL FOR TODAY WITH MOISTURE HIGH AND THE
TROUGH AXIS OVERHEAD. BEST LIFT AND DIFFLUENCE WILL BE ACROSS THE
EASTERN THIRD OF THE CWA WITH DRIER MID LEVEL AIR WORKING IN ON THE
BACKSIDE OF THE TROUGH. DESPITE INCREASING MID LEVEL DRY AIR...SFC-
500MB MOISTURE WILL REMAIN ABUNDANT FOR CONVECTION TO GET GOING
ALONG THE SEA BREEZE TODAY. AM EXPECTING SCATTERED COVERAGE
BEGINNING IN THE COASTAL SECTIONS THIS MORNING THEN WORKING
WESTWARD WITH TIME WITH THE SEA BREEZE BEING THE MAIN FOCUS WITH
OUTFLOWS DRIVING CONVECTION AS WELL THIS AFTERNOON. INVERTED-V
POINT SOUNDINGS ALL ACROSS THE CWA TODAY SO WILL CONTINUE GUSTY
WIND MENTION FROM PREVIOUS SHIFT.

STORM MOTIONS WILL BE FAIRLY SLOW TODAY...AROUND 20 MPH OR LESS.
STORMS WILL BE EFFICIENT RAINMAKERS AS WELL WITH A FAIRLY
SATURATED COLUMN. WITH YESTERDAY`S HEAVY RAINFALL ESPECIALLY
ACROSS CAMERON COUNTY...WILL NEED TO KEEP A CLOSE EYE ON RAINFALL
RATES AND AMOUNTS AS IT WON`T TAKE MUCH TO HAVE FLOODING CONCERNS
IN THE LOWER VALLEY.

CONVECTION WILL WANE THIS EVENING WITH SLIGHT CHANCE POPS ACROSS
THE RIO GRANDE PLAINS EARLY TONIGHT. ONCE AGAIN CONVECTION WILL
GET GOING ACROSS THE COASTAL WATERS TONIGHT. MOISTURE SLOWLY
DECREASES WEDNESDAY BUT NOT ENOUGH TO SIGNIFICANTLY REDUCE
COVERAGE. THEREFORE...EXPECT ISOLATED TO SCATTERED CONVECTION
FAVORING THE COASTAL SECTIONS WEDNESDAY MORNING THEN PROGRESSING
TO THE MID VALLEY AND RANCHLANDS WEDNESDAY AFTERNOON.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...WITHIN A BROAD
HEIGHT PATTERN AT H5 WILL LIE A WEAK TROUGH ALONG THE GULF COAST
AND TEXAS COAST...EXTENDING INTO THE ARKLATEX REGION ON WEDNESDAY.
PART OF THE PROBLEM AFTER THAT IS THAT THE WEAKNESS IS RATHER
SHALLOW RELATIVE TO THE SURROUNDING HEIGHT FIELD...AND THEREFORE
WILL TEND TO BUBBLE AROUND A BIT...THOUGH MORE OVER THE GULF. IT
MIGHT BE EASIER TO STATE THAT H5 RIDGING APPEARS MORE DEFINED FROM
NORTH CENTRAL MEXICO NORTHEAST ACROSS TEXAS AND INTO THE CENTRAL
PLAINS DURING THE LATTER HALF OF THE WEEK. H5 HEIGHTS THAT ARE 5
TO 10 DECAMETERS LOWER DO SEEM TO BE MORE IDENTIFIABLE OVER THE
GULF GOING INTO THE WEEKEND AND EARLY NEXT WEEK. RICH LOW LEVEL
MOISTURE COMBINED WITH THE UPPER WEAKNESS WILL FUEL A LOT OF
MARINE BASED CONVECTION WHICH IS MAINTAINED THROUGH THE LONG TERM.
THIS WILL BE BLENDED ASHORE AND INLAND...WITH THE BEST CHANCES
GENERALLY EAST OF US 281/IH 69C. THE ECMWF GUIDANCE ADVERTISES A
BIT HIGHER POP NUMBERS THROUGH THE LONG TERM THAN THE GFS...BUT
NOT EXCESSIVELY SO...AND A BLEND OF THE TWO...WHILE PERHAPS NOT
DOING COMPLETE JUSTICE TO EITHER MODEL...STRUCK A BALANCE WHICH
STILL CONVEYS THE CONTINUED CONSENSUS OF UNSETTLED WEATHER. OTHER
SENSIBLE WEATHER ELEMENTS REMAIN CLOSE TO THE PREVIOUS FORECAST.
WITH CLOUD COVER AND RAIN CHANCES...HIGH TEMPS WILL BE MAINLY IN
THE 90S...LOWER 90S EAST TO UPPER 90S FAR WEST...NEAR NORMAL EAST
TO SLIGHTLY ABOVE NORMAL WEST.

MARINE...
NOW THROUGH WEDNESDAY...WEAK HIGH PRESSURE WILL SUPPORT LIGHT TO
MODERATE SOUTHEAST WINDS AND LOW TO MODERATE SEAS. SHOWERS AND
THUNDERSTORMS WILL INCREASE NOW THROUGH WEDNESDAY DUE TO
INSTABILITY ALOFT AND INCREASED MOISTURE MOVING UP FROM SOUTH OF
THE AREA.

WEDNESDAY NIGHT THROUGH SATURDAY...REMARKABLY PERSISTENT WINDS
AND SEAS WILL CONTINUE IN THE LONG TERM...WITH LIGHT TO MODERATE
SOUTHEAST WINDS AND LOW SEAS. THIS WILL BE THE RESULT OF A BROAD
HIGH PRESSURE FIELD ACROSS THE NORTH GULF. THE WEATHER WILL REMAIN
UNSETTLED HOWEVER...WITH AN ALMOST CONTINUOUS CHANCE OF MARINE
SHOWERS AND THUNDERSTORMS THROUGH THE LONG TERM.

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

$$

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