Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 241133 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
633 AM CDT THU JUL 24 2014

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

&&

.AVIATION...CUMULUS DECK TO STEADILY DEVELOP THROUGH THE MORNING
WITH ISOLATED SHOWERS AND THUNDERSTORMS DURING THE LATE MORNING
AND AFTERNOON. THE CONVECTION IS EXPECTED TO BE CIRCUMNAVIGABLE
WITH VFR CONDITIONS. LOW CONFIDENCE ON CONVECTION IMPACTING THE 3
REGIONAL TAFS SITE AND IF SO CONDITIONS SHOULD BE SHORT LIVED.
LIGHT AND VARIABLE TO CALM WINDS THIS MORNING BECOMING SOUTHEAST
TO EAST AT LIGHT TO MODERATE LEVELS THIS AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 354 AM CDT THU JUL 24 2014/

SHORT TERM /TODAY THROUGH FRIDAY/...WEAK MID TO UPPER LEVEL SHEAR
AXIS LIES ALONG THE TEXAS COAST AND WILL CONTINUE TO DRIFT AND
BECOMING INCREASINGLY ELONGATED AS IT TRACKS AROUND THE EASTERN
PERIPHERY OF THE WESTERN RIDGE. MODEST DAYTIME INSTABILITY A WEAK
SEA BREEZE /PROVIDING WEAK CONVERGENCE/ TO COMBINE WITH
DISTURBANCE PRODUCING A ISOLATED SHOWERS AND THUNDERSTORMS LATE
THIS MORNING INTO THE AFTERNOON. NAM IS TRENDING HIGHER THEN THE
GFS/ECMWF A BLEND OF THE TWO LOOKS REASONABLE WHICH TRANSLATES
INTO A BROAD BRUSH OF 20 PERCENT FOR MOST OF THE CWA WITH BEST
CHANCES ALONG AND EAST OF 69C. LIMITING FACTOR IS MOISTURE WITH
PWATS HOVERING AROUND 1.6 INCHES AND MEAN RH AROUND 60 PERCENT TO
700MB WHICH IS HIGHER THEN THE LAST FEW DAYS BUT STILL BELOW
NORMAL. AN INCREASE IN CUMULUS FIELD THIS AFTERNOON WITH A
THICKENING CIRRUS DECK IF ANY CONVECTION BLOSSOMS. TEMPERATURES TO
CLIMB FAIRLY RAPIDLY WITH MAXIMUMS TO SHOW LITTLE TO NO CHANGE
FROM THE LAST FEW DAYS.

TONIGHT...CONVECTION TO WANE WITH SOME LINGERING SHOWERS OVER
THE GULF AS THE SHEAR LINE CONTINUES TO WEAKEN. HIGHER CLOUDS TO
THIN AND TEMPERATURES WILL SEE A SLOW FALL BOTTOMING OUT IN THE MID
70 TO NEAR 80.

FRIDAY...GFS AND NAM DAMPENS OUT THE SHEAR LINE WHILE THE ECMWF
MAINTAINS A WEAK LOW AT 250MB AND CENTERS IT ACROSS THE LOWER AND
MID VALLEY. WHILE THE EC AND GFS INDICATE VERY LOW POPS NAM IS
PUSHING 30 PERCENT. GFS AND NAM 850-700MB WINDS ARE TRENDING MORE
SOUTHWEST AS THE SHEARLINE DRIFTS TO OUR WEST WHICH PUSHING THE 85H
TEMPERATURES UP 1-2C. GFS IS TRENDING LOWER ON THE MEAN RH WHILE NAM
IS RATHER AGGRESSIVE WITH MUCH HIGHER AND DEEPER RH VALUES.
CLIMATOLOGY AND LOW CONFIDENCE DICTATES TO TREND ON THE LOWER END OF
GUIDANCE WITH NO POPS ADDED INTO THE FORECAST AT THIS TIME. WILL
HAVE TO LOOK AT LATER MODEL RUNS WITH DAY CREW ANALYZING TODAY`S
CONVECTIVE TREND TO LATER DETERMINE IF ANY POPS ARE NEEDED TO ADDED
IN FOR FRIDAY. AS FOR TEMPERATURES EXPECT A STEADY STATE
TEMPERATURES PROFILE WITH PLENTY OF WARMTH TO GO AROUND.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...THE INFLUENCE OF THE
BROAD WESTERN RIDGE DOMINATES THE FORECAST ACROSS SOUTH TEXAS FOR
THE EXTENDED PERIOD. PW VALUES OF 1.5 TO 1.6 ARE NOT CONDUCIVE TO
THE FORMATION OF PRECIPITATION...AND COMBINED THE SUBSIDENCE FROM
THE NEARBY RIDGE WILL KEEP RAINFALL CHANCES OUT OF THE FORECAST
THROUGH THE MIDDLE OF NEXT WEEK. MAIN WEATHER CONCERN IS THE
OPPRESSIVE SUMMERTIME HEAT. TEMPERATURES WILL CONTINUE TO REACH
THE MID 90S TO LOW 100S EACH DAY...WITH LOWS IN THE UPPER 70S TO
AROUND 80. HEAT INDEX VALUES REMAIN 105 TO 110 DURING THE
DAY...WITH MINIMUM OVERNIGHT HEAT INDEX VALUES REMAINING 85 TO 90.

MARINE...
TODAY THROUGH FRIDAY...LATEST BUOY REPORT INDICATES LIGHT WINDS AND
NEARLY FLAT SEAS ACROSS THE COASTAL WATERS. WEAK PRESSURE GRADIENT
TO PERSIST WITH LITTLE CHANGE IN FAVORABLE MARINE CONDITIONS.
HOWEVER AN INCREASE IN SHOWERS AND THUNDERSTORMS IS ANTICIPATED
LATER TODAY AS A WEAK UPPER AIR DISTURBANCE OVER THE NORTHWEST GULF
TRACKS SOUTHWEST. ISOLATED TO SCATTERED ACTIVITY CAN BE EXPECTED TO
DEVELOP AROUND SUNRISE AND PERSIST THROUGH THE MORNING WITH A
DIMINISHING TREND LATER THURSDAY EVENING.

FRIDAY NIGHT THROUGH MONDAY...MODEST MARINE CONDITIONS CONTINUE
FOR THE EXTENDED FORECAST AS BROAD HIGH PRESSURE REMAINS ACROSS
THE GULF AND WEAK SUMMERTIME HEAT LOW REMAINS PERSISTENT ACROSS
FAR WEST TEXAS. SOUTHEAST WINDS WILL GENERALLY RUN 10 TO 15KTS
EACH DAY. THIS WILL HAVE MINIMAL EFFECT ON THE SEAS...WITH SWELLS
GENERATING MORE FROM LONG FETCH ACROSS GULF OF 2 TO 3 FEET OVER
THE WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  95  79  94  79 /  20  10  10  10
BROWNSVILLE          96  78  94  79 /  20  10  10  10
HARLINGEN            98  76  98  77 /  20  10  10  10
MCALLEN             100  78  99  78 /  20  10  10  10
RIO GRANDE CITY     101  78 101  78 /  10  10  10  10
SOUTH PADRE ISLAND   90  79  90  81 /  20  10  10  10

&&

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

$$

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