Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 211828 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
128 PM CDT MON JUL 21 2014

.DISCUSSION...UPDATED FOR LATEST /18Z/ AVIATION DISCUSSION BELOW.

&&

.AVIATION...MORNING SOUNDING SHOWED A DEEP LAYER OF DRY AIR ABOVE
THE MORNING INVERSION...AND THIS HAS MIXED OUT MOST LOWER CLOUDS
AWAY FROM THE COAST WITH JUST A FEW LOW VFR (3-4K FEET) RANGE
ABOUT 15-20 MILES INLAND FROM THE COAST. OTHERWISE...25-30 KT
SOUTHEAST WINDS OFF THE DECK THIS MORNING MIXING DOWN IN
GUSTS AT THE SURFACE...GENERALLY IN THE 18-24 KNOT RANGE. THIS
SHOULD CONTINUE THROUGH SUNSET.

AFTER SUNSET...JUST A FEW MVFR CUMULUS NEAR THE COAST OTHERWISE
DIMINISHING WINDS BELOW 10 KNOTS AFTER 03Z. DESPITE THE ARRIVAL OF
DRIER ATMOSPHERIC AIR...LOW LEVEL DEWPOINTS WILL REMAIN RATHER
HIGH NEAR THE COAST OVERNIGHT AND 3-HOURLY MODEL SOUNDINGS SHOW
A RETURN OF LOW MVFR CEILINGS SOMETIME BETWEEN 07 AND 09Z. SIMILAR
TO THIS MORNING...THESE SHOULD CONTINUE UNTIL 14/15Z BEFORE
ERODING TO FEW-SCT WITH AMPLE SUNSHINE/MIXING AS SOUTHEAST WINDS
PICK UP THOUGH ABOUT 3-5 KNOTS LESS THAN TODAY.

WINDS LOWERING BELOW 5 KNOTS COMBINED WITH THE CURRENT HAZY
(ALOFT) CONDITIONS COULD ALLOW SETTLING OF THE HAZE INTO A 4-6
MILE VISIBILITY...BUT CONFIDENCE NOT ENOUGH TO ADD AT THIS POINT.
52/BSG


&&

.PREV DISCUSSION... /ISSUED 636 AM CDT MON JUL 21 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...PATCHY FOG IN SOME LOCATIONS AND A FEW AREAS WITH
MVFR CEILINGS WILL CONTINUE TO IMPACT PORTIONS OF DEEP SOUTH
TEXAS FOR THE NEXT 2 HOURS. THIS CONDITIONS IMPROVE TO VFR FOR
THE REMAINDER OF THE DAY WITH SOUTHEAST WINDS INCREASING AFTER
15Z THIS MORNING. THE PRESSURE GRADIENT WILL WEAKEN A FEW HOURS
AFTER SUNSET ALLOWING FOR THE SE WINDS TO DIMINISH AFTER AND
REMAIN LIGHT THROUGH THE NIGHT.

PREV DISCUSSION... /ISSUED 339 AM CDT MON JUL 21 2014/

SHORT TERM /NOW THROUGH TUESDAY/...CURRENT WATER VAPOR IMAGERY AND
500MB HEIGHT SHOWS STRONG 594DM H5 HIGH CENTERED OVER NEW MEXICO
DOMINATING MOST OF THE DESERT SW AND SOUTH TEXAS WHILE A TROUGH DIGS
SE OVER THE EASTERN PORTION OF THE CONUS. THIS UPPER HIGH WILL BUILD
AND SHIFT NORTH TODAY AND CONTINUE TO BUILD TO 599DM OVER SOUTHERN CO
INTO TUESDAY. HEIGHTS WILL RISE WELL ABOVE NORMAL TODAY AS THIS HIGH
STRENGTHENS ACROSS THE CWA AND THE 850MB TEMPERATURES CLIMB FROM 22
TO 24 DEG CELSIUS RISING TEMPS TODAY FROM 100 TO 105 DEGREES FOR MOST
LOCATION ALONG AND WEST OF HIGHWAY 77. HEAT INDEX OR "FEEL LIKE"
TEMPERATURES ACROSS THE CWA WILL BE NEAR HEAT ADVISORY CRITERIA
FEELING BETWEEN 105 TO 110 ACROSS THE AREA. SURFACE PRESSURE
GRADIENT WILL STRENGTHEN INCREASING SE WINDS ACROSS THE AREA TODAY
WITH WIND GUSTS INCREASING BETWEEN 20 TO 25 MPH ESPECIALLY ALONG THE
COASTAL COUNTIES. 1000 TO 500MB RH SHOWS MOISTURE CONTENT REMAINING
LESS THAN 54 PERCENT ACROSS THE CWA LIMITING ANY SHOWER DEVELOPMENT
TODAY. TONIGHT LOWS WILL REMAIN WARM IN THE LOW 80S ALONG THE BORDER
WITH A FEW LOCATIONS OVER THE RANCHLAND AREA IN THE UPPER 70S WITH
NO CHANCE OF RAIN.

TUESDAY...THE SAME WEATHER PATTERN CONTINUES WITH LESS MOISTURE IN
THE AREA AND HEIGHTS A BIT LOWER COMPARED TO WHAT IS EXPECTED TODAY.
THIS WILL KEEP HIGH TEMPERATURES IN THE TRIPLE DIGITS WEST OF
HIGHWAY 281 BUT WILL GIVE A BIT OF A BREAK EAST OF HIGHWAY 281 RANGING
FROM 99 TO 95 DEGREES. SOUTHEAST WINDS WILL INCREASE ONCE AGAIN IN
THE AFTERNOON WITH NO CHANCE OF RAIN.

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...IN A WORD: DEPRESSING.
BROAD 500 MB HIGH PRESSURE IS EXPECTED TO REMAIN CENTERED OVER
THE FOUR CORNERS AREA OF THE UNITED STATES...WITH A ADDITIONAL 500
MB HIGH CENTERED OVER THE BAHAMAS. BOTH OF THESE HIGHS WILL PERSIST
OVER DEEP SOUTH TEXAS AND RIO GRANDE VALLEY AND GULF OF MEXICO.
WITH PRECIPITABLE WATER VALUES LIKELY TO HOLD AROUND 1.5 INCHES
IN TANDEM WITH THE HIGHS...DRY WEATHER AND HOT TEMPERATURES WILL
RESULT. THE ONLY HOPE FOR CHANGE THAT EXISTS IN THE LONG TERM
FORECAST PERIOD IS A CLOSED 500 MB LOW THAT EXISTS OVER LOUISIANA
AT THE START OF THE PERIOD...BUT GETS STRETCHED AND ABSORBED INTO
A LONGWAVE 500 MB TROUGH THAT SETS UP OVER THE EASTERN UNITED
STATES IN BETWEEN THE TWO PREVIOUSLY-MENTIONED 500 MB HIGHS. IF
THE LOW COULD ACTUALLY HOLD TOGETHER AND RETROGRADE TOWARDS THE
BRO CWFA...SOME PRECIPITATION COULD EXIST FOR THIS REGION. FOR NOW
HOWEVER...THIS SCENARIO DOES NOT APPEAR LIKELY.

MARINE...NOW THROUGH TUESDAY...SURFACE HIGH PRESSURE WILL
STRENGTHEN TODAY AS HIGH PRESSURE BUILDS ACROSS THE GULF OF MEXICO.
SE WINDS WILL INCREASE AND BUILD SEAS TO AROUND 3 FEET WITH MODERATE
WINDS. WINDS WILL BE CLOSE TO SCEC FOR A FEW HOURS IN THE AFTERNOON
OVER THE LAGUNA BUT WILL QUICKLY DIMINISH AFTER SUNSET. CONDITIONS
OVER THE GULF WILL REMAIN MODERATE AS THE PRESSURE GRADIENT KEEPS
WINDS AROUND 15 KNOTS OVER THE GULF WATERS. AT THIS TIME NO CHANCE
OF SHOWERS WILL BE POSSIBLE AS THE DRY AIR MASS DOMINATES THE AREA.

TUESDAY NIGHT THROUGH SUNDAY...SURFACE HIGH PRESSURE CENTERED OVER
THE EASTERN GULF OF MEXICO AND EXTENDED FAR INTO THE WESTERN GULF
OF MEXICO WILL PRODUCE VERY FAVORABLE MARINE CONDITIONS ALONG THE
LOWER TEXAS COAST THROUGH THE ENTIRE PERIOD...WITH LIGHT TO MODERATE
WINDS AND LOW TO MODERATE SEAS LIKELY. HOWEVER...WINDS OVER THE
LAGUNA MADRE MAY BE STRONG ENOUGH TO REQUIRE A SMALL CRAFT EXERCISE
CAUTION AROUND THE END OF THE WEEK INTO THE FIRST HALF OF THE
WEEKEND.

&&

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

$$

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