Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 291926
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
226 PM CDT WED JUL 29 2015

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

&&

.AVIATION...PWAT VALUES HAVE INCREASED A BIT ACCORDING TO THE 12Z
BRO SOUNDING. THE LOW CLD DECKS WERE A BIT MORE WIDESPREAD EARLY
THIS MORNING ACROSS THE RGV AND WILL INCLUDE A MENTION OF THESE
FOR THE HRL AND BRO AIRPORTS THROUGH EARLY THURSDAY MORNING. THIS
MAY RESULT IS A LITTLE MORE WIDESPREAD MVFR/IFR CONDITIONS FOR A
FEW HOURS TOMORROW. OTHERWISE VFR CEILINGS WILL PREVAIL FOR MOST
OF THE UPCOMING TAF PERIOD. WILL ALSO INCLUDE A MENTION OF SOME
LIGHT HAZE FOR THE RGV AIRPORTS AS VSBL SATL IMAGERY THIS
AFTERNOON INDICATES AN AREA OF SMOKE/HAZE MOVING FROM SE TO NW
ACROSS THE SW GULF OF MEX.

&&

.PREV DISCUSSION... /ISSUED 624 AM CDT WED JUL 29 2015/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...UPPER LEVEL HIGH PRESSURE HAS VEER WINDS MORE
SOUTHEASTERLY ACROSS THE GULF OF MEXICO. THIS WILL RESULT IN
AN INCREASE OF HAZE UNDER THE INVERSION ESPECIALLY FOR THE
EARLY MORNING HOURS. SHALLOW LOW LEVEL MOISTURE WILL SUPPORT FOR
LOW LEVEL BKN TO SCT CLOUD DECK TO DEVELOP OVER THE THREE TERMINAL
IN THE RGV. THIS MVFR CIGS WILL BEGIN TO BREAK AND MIX OUT WITH
DAYTIME HEATING THIS AFTERNOON WITH VFR EXPECTED FOR THE REMAINDER
OF THE DAY. NO CHANCE OF RAIN IS EXPECTED AT THIS TIME WITH VFR
PREVAILING DURING DAYTIME HOURS. WINDS DECOUPLE A FEW HOURS AFTER
SUNSET.

PREV DISCUSSION... /ISSUED 339 AM CDT WED JUL 29 2015/

SHORT TERM /NOW THROUGH THURSDAY/...LATEST WATER VAPOR AND 500 DAM
HEIGHTS SHOWS BROAD HIGH PRESSURE CURRENTLY CENTERED OVER NORTHEAST
TX AND OKLAHOMA WITH HIGHER MOISTURE CONTENT CIRCULATION AROUND THE
PERIPHERY OF THIS HIGH. LOWER AND MID LEVEL MOISTURE IS SLIGHTLY
INCREASING ACROSS SOUTH TEXAS AND THIS IS ASSOCIATED TO A
DISTURBANCE OVER THE EASTERN GULF COAST MOVING WEST INTO S TX. THIS
WEATHER PATTERN WILL PUT THE REGION UNDER A MORE EASTERLY FLOW
ALOFT...MODERATE EAST TO SE WINDS AND A LOW POSSIBILITY OF SHOWERS
AND STORMS LATE WEDNESDAY INTO THURSDAY. LATEST PRECIPITABLE WATER
VALUES IN THE 00Z KBRO SOUNDING SHOWS A SLIGHT INCREASE OF 1.5
IN.CHES WITH LOWER LEVEL MOISTURE AND IN THE MID LEVELS AT AROUND
500 MB HEIGHT. THIS WILL MAINLY INCREASE CLOUD COVER THIS AFTERNOON
TO PARTLY CLOUDY CONDITIONS. THICKNESS VALUES SHOW A STRONG GRADIENT
OVER HIDALGO AND STARR COUNTIES WHILE A BIT WEAKER NEAR THE COAST.
THIS WILL RESULT IN TEMPERATURES RANGING ONCE AGAIN INTO THE TRIPLE
DIGITS WEST OF HWY 77 AND 281. AS DAYTIME HEATING COMMENCES...DRY
AIR ALOFT WILL MIX DOWN TO THE SURFACE HELPING TO MIX SOME OF THIS
LOWER DEW POINTS DOWN TO THE SFC. DO EXPECT DEW POINT VALUES TO
REMAIN IN THE LOW 70S NEAR THE COAST AND NEAR MID TO LOW 60S TOWARDS
THE WESTERN COUNTIES. RH VALUES WILL REACH ABOVE 40 PERCENT NEAR THE
COAST TO LOW 20 PERCENT OVER STARR...JIM HOGG AND ZAPATA COUNTIES
RESULTING IN LOWER HEAT INDEX VALUES ACROSS DEEP SOUTH TEXAS TODAY
AND INTO THURSDAY. LOCATIONS TOWARDS THE WEST COULD SEE A SMALL
WINDOW WHERE CONDITIONS COULD BE FAVORABLE FOR CRITICAL FIRE
WEATHER. DO NO EXPECT WINDS TO REMAIN AS BREEZE INTO THURSDAY WHICH
WILL LOWER THE POTENTIAL CRITICAL FIRE WEATHER CONDITIONS. HIGH
TEMPS INTO THURSDAY WITH MORE CLOUD COVER ARE EXPECTED TRENDING A
FEW DEGREES LOWER COMPARED TO WEDNESDAY.

EARLY THURSDAY MORNING WITH NOCTURNAL INVERSION EXPECT...AN INCREASE
IN CLOUD COVER WITH MODERATE HAZE CONCENTRATION WILL BE NOTED EARLY
DURING SUNRISE. AS DAYTIME HEATING BEGINS...THIS HAZE WILL MIX OUT
CLEARING THE VISIBILITY. HOWEVER...A MORE EASTERLY FLOW NEAR THE
COAST WITH A WEAKER PRESSURE GRADIENT SETTING UP WILL AID FOR SEA
BREEZE TO DEVELOP AND PUSH INLAND THURSDAY. EXPECT HIGHER CLOUD
COVERAGE AND A CHANCE OF SHOWERS TO DEVELOP ALONG THE COAST WHILE
DRY CONDITIONS REMAIN TOWARDS THE WEST. THE THICKNESS VALUES AND 850
MB TEMPS SHOW A SLIGHT DECREASE... THEREFORE...LEAN TOWARDS A FEW
DEG LOWER FOR TEMPERATURES THURSDAY. HIGH`S NEAR HARLINGEN...MCALLEN
AND WEST OF MCALLEN WILL RANGE BETWEEN 99 TO 105 AND MID 90S ALONG
THE COAST.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...THE MOST SIGNIFICANT
CHANGE TO THE LONG TERM PORTION OF THE FORECAST WAS TO INCREASE
PRECIPITATION CHANCES TO AS HIGH AS 30 PERCENT FOR A PORTION OF
THE BRO CWFA ON SATURDAY. ISOLATED SHOWERS AND/OR THUNDERSTORMS
ARE FORECAST MAINLY ALONG AND EAST OF THE HIGHWAY 77/INTERSTATE
69E CORRIDOR FOR FRIDAY THROUGH FRIDAY NIGHT AS PRECIPITABLE WATER
VALUES INCREASE TO AROUND 2 INCHES WHILE A WEAK 500 MB TROUGH
APPROACHES FROM THE EAST. PRECIPITATION CHANCES RAMP UP TO 20-30
PERCENT FOR SATURDAY AND SATURDAY NIGHT AS THE VALUES INCREASE
EVEN FURTHER TO NEAR 2.4 INCHES AS A WEAK COLD FRONT BRIEFLY
STALLS ALONG THE TEXAS COASTLINE BEFORE RAPIDLY DISSIPATING. THE
REMAINDER OF THE FORECAST IS DRY WITH 500 MB HIGH PRESSURE
CENTERED OVER THE FOUR CORNERS AREA BUILDING FARTHER TO THE
SOUTHEAST WHILE PRECIPITABLE WATER VALUES DROP BACK TO NEAR 1.5
INCHES. THE COOLEST TEMPERATURES ARE EXPECTED FRIDAY AND SATURDAY
IN ASSOCIATION WITH THE MORE MOIST ATMOSPHERE AND OPPORTUNITY FOR
RAINFALL...HOWEVER...ABOVE NORMAL TEMPERATURES REMAIN LIKELY FOR
THE ENTIRE LONG TERM FORECAST PERIOD.

MARINE...NOW THROUGH THURSDAY...BROAD SURFACE HIGH OVER THE GULF OF
MEXICO WILL KEEP SOUTHEAST WINDS ACROSS THE GULF DURING THE SHORT
TERM PERIOD. AT THIS TIME...SCEC CONDITIONS CONTINUE THROUGH THE
EARLY MORNING ACROSS THE GULF LOWERING DURING THE DAY. THE GRADIENT
WILL STRENGTHEN OVER THE LAGUNA TODAY WITH SCEC CONDITIONS
RETURNING. INTO THURSDAY GRADIENT WILL NOT BE AS STRONG WITH NO SCEC
EXPECTED OVER THE LAGUNA. SEAS WILL REMAIN BETWEEN 2 TO 3 FEET
THROUGH THE PERIOD.

THURSDAY NIGHT THROUGH TUESDAY...LIGHT TO MODERATE WINDS AND LOW
TO MODERATE SEAS WILL PREVAIL ALONG THE LOWER TEXAS COAST WITH
SURFACE HIGH PRESSURE IN CONTROL. SMALL CRAFT MAY NEED TO EXERCISE
CAUTION ON THE LAGUNA MADRE FROM SUNDAY THROUGH TUESDAY DUE TO
SLIGHTLY BREEZIER WINDS.

&&

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

$$

THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WEATHER.GOV/RGV

SHORT TERM...60
LONG TERM...63
GRAPHICAST/UPPER AIR...58


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