Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 271741 AAC
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1241 PM CDT WED APR 27 2016

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

&&

.AVIATION...WEAK COLD FRONT HAS MOVED OFFSHORE EARLIER THIS
MORNING. IN ITS WAKE DRIER NORTHWEST TO NORTHEAST WINDS TO WASH
OUT MUCH OF THE HAZE WITH VISIBILITIES IMPROVING THROUGH THE
AFTERNOON. VFR CONDITIONS TO PREVAIL WITH SOME BRIEF BKN VFR
CLOUDS DECKS AT THE 3 REGIONAL AIRPORTS. THE FRONT RETURNS
OVERNIGHT AS A WARM FRONT WITH SOUTHEAST WINDS AND GULF MOISTURE
ON THE INCREASE. EXPECT A RETURN OF LOW CLOUDS AND MVFR CIGS AS
WELL AS SOME LIGHT FOG AROUND MIDNIGHT LOWERING TO IFR BEFORE
SUNRISE THURSDAY. DEPENDING ON THE NORTHWARD MOVEMENT OF THE FRONT
THE LOWER CONDITIONS MAY LINGER THROUGH MID TO LATE MORNING BEFORE
MVFR TO VFR CONDITIONS DEVELOP THURSDAY AFTERNOON. WINDS WILL BE
LIGHT AND VARIABLE TO EAST INTO THE EVENING WITH SOUTHEAST WINDS
INCREASING THURSDAY WITH GUSTS TO 25 KNOTS DURING THE AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 1027 AM CDT WED APR 27 2016/

DISCUSSION...THE WEAK COLD FRONT HAS MOVED OFF THE COAST LIKELY
TO AN INCREASE IN FORWARD MOMENTUM FROM LAST NIGHTS CONVECTION
OVER THE MIDDLE TEXAS COAST. LITTLE TEMPERATURE CHANGE BEHIND THE
FRONT WITH A GRADUAL DRYING OF THE LOW LAYERS. THIS MAY
TEMPORARILY PUSH THE HAZY SKIES OFFSHORE AND CLEAR OUT THE CLOUDS
FOR THE AFTERNOON. LIGHT WINDS AND MOSTLY SUNNY CONDITIONS TO PUSH
TEMPERATURES UP BUT HAVE LOWERED JUST A DEGREE OR TWO FROM THE
EARLIER FORECAST. HIGHS WILL BE STILL BE 5 TO 8 DEGREES ABOVE
NORMAL. DECREASED THE CLOUD COVER ADJUSTED WINDS AND WILL TAKE OUT
THE RAIN AND REDUCE THE HAZE FOR THE AFTERNOON.

PREV DISCUSSION... /ISSUED 729 AM CDT WED APR 27 2016/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...THE SOUTHERN END OF THE CONV THAT IMPACTED CENTRAL TX
EARLIER HAS DIMINISHED IN CONVERAGE WITH THE STRONGEST T-STORM IN
THE AREA NOW HEADING EAST FOR THE COASTAL BEND. OTHERWISE IR SATL
IMAGERY AND SURFACE OBS SHOW LOW LEVEL SC PERSISTING ACROSS MUCH
OF DEEP SOUTH TX. THESE LOW CEILINGS WILL CONTINUE ON THROUGH THE
REST OF THE EARLY MORNING HOURS AS A MOIST LOW LEVEL LAYER OF THE
ATMS REMAINS IN PLACE. A FAIRLY STRONG LOW LEVEL INVERSION IS ALSO
EVIDENT THIS MORNING ON THE BRO SOUNDING FROM 920 TO AROUND 970
MBS. THE NAM FORECAST SOUNDINGS SHOW THIS LOW LEVEL INVERSION
WEAKENING BUT STILL HOLDING IN PLACE THROUGH MIDDAY WHICH WILL
TEND TO MAINTAIN THE IFR/MVFR CEILINGS THROUGHOUT THE MORNING. A
WINDOW OF VFR CONDITIONS IS EXPECTED LATER THIS AFTERNOON AND
EARLY THIS EVENING AS THE LOW LEVEL MIXING OF THE ATMS PEAKS WITH
THE DAYTIME HEATING. THE LOW CEILINGS WILL RETURN ONCE AGAIN LATE
TONIGHT THROUGH EARLY THURS MORNING AS THE MOIST LOW LEVEL
INVERSION RETURNS RESULTING IN SOME IFR CEILINGS. FINALLY SMOKE
AND HAZE ADVECTING UP FROM THE AG BURNING ONGOING IN SOUTHERN
MEXICO AND CENTRAL AMERICA WILL MAINTAIN VSBSY IN THE 4 TO 6 NM
RANGE THROUGHOUT THE NEXT 24 TO 48 HOURS WITH SOME FOG FORMING
DURING THE LATE NIGHT AND EARLY MORNING HOURS AS THE TEMP AND
DEWPOINT SPREAD NARROWS.

PREV DISCUSSION... /ISSUED 422 AM CDT WED APR 27 2016/

SHORT TERM  /TODAY THROUGH THURSDAY/...THE FIRST ITEM OF CONSIDERATION
FOR THIS MORNING CONCERNS THE CONV LINE THAT IS CURRENTLY MOVING SE
ACROSS CENTRAL TX HEADING TO THE TX COASTLINE AHEAD OF THE WEAK COLD
FRONT MOVING THROUGH THE STATE. THE 00Z BRO SOUNDING SHOWS SOME GOOD
CAPE VALUES IN PLACE OVER THE RGV BUT WITH A FAIRLY DRY AND CAPPED
SOUNDING EVIDENT. LAPS DATA SHOWS CAPE VALUES RANGING FROM 2100 -
2500 J/KG ACROSS THE INLAND AREAS GENERALLY WITH SOMEWHAT HIGHER
VALUES LOCATED OVER THE LOWER TX GULF WATERS. LAPS DATA ALSO SHOWS
CONSIDERABLE CIN VALUES ACROSS MUCH OF THE INLAND AREAS WITH LOWER
VALUES LOCATED OVER THE MARINE AREAS. SO EXPECT THE SOUTHERN END OF
THE CONV LINE APPROACHING THE TX COASTLINE TO WEAKENAS IT APPROACHES
THE RGV WITH SOME OF THE CONV PROBABLY MAKING IT INTO THE LOWER TX
MARINE AREAS.

THE COLD FRONT WILL PUSH INTO DEEP SOUTH TX POSSIBLY RESULTING IN A
BRIEF SHIFT IN THE SURFACE WINDS FROM THE NORTH. FURTHER NORTH...THE
500 MB TROUGH AXIS THAT BROUGHT THE COLD FRONT INTO THE STATE WILL
LIFT OUT TO THE NORTHEAST HEADING FOR THE CENTRAL PLAINS STATES
LATER TODAY. ANOTHER 500 MB CLOSED LOW WILL THEN DIG SE ALONG THE
WEST COAST OF THE U.S. PUSHING INTO DESERT SW ON THURS. THIS WILL
RESULT IN A 500 MB RIDGE STEADILY BUILDING OVER THE GULF OF MEX.
MEAN HUMIDITY VALUES WILL DIMINISH AS THE RIDGE AXIS BUILDS OVER THE
GULF. 1000-500 MB THICKNESS WILL BE ON THE INCREASE THROUGH WED AND
THURS WHICH IN COMBINATION WITH THE LIMITED MOISTURE VALUES OVER THE
AREA WILL ALLOW TEMPS TO WARM UP NICELY. BOTH THE MAV AND ECMWF TEMP
GUIDANCE ARE THE WARMEST OF THE THREE SHORT TERM MODEL SETS WITH THE
MET SHOWING UP AS THE COOLEST. WILL GO CLOSER TO THE WARMER MODEL
SETS SINCE THE NAM GUIDANCE IS THE OUTLIER.

THE LATEST AIR QUALITY GUIDANCE FROM TCEQ INDICATES THAT HAZE AND
SMOKE FROM AG BURNING ONGOING IN SOUTHERN MEXICO AND CENTRAL AMERICA
WILL CONTINUE TO MOVE OVER THE RGV DEGRADING THE VSBYS AND OVERALL
AIR QUALITY. WILL MAINTAIN A MENTION OF THE HAZE/FOG THROUGHOUT
TODAY AND THURS WITH TCEQ GUIDANCE ANTICIPATING THE WORST AIR
QUALITY FOR THE RGV ON THURS. TCEQ ANTICIPATES THURSDAY AIR QUALTIY
TO FALL INTO THE "UNHEALTHY FOR SENSITIVE GROUPS" CATEGORY.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...WEST TO SOUTHWEST
FLOW ALOFT WILL CONTINUE OVER THE REGION AS A SERIES OF 500MB LOWS
PREVAIL ACROSS THE ACROSS THE WESTERN CONUS THROUGH EARLY NEXT WEEK.

HOT AND DRY CONDITIONS WILL PREVAIL ACROSS DEEP SOUTH TEXAS ON
FRIDAY WITH SHALLOW MOISTURE AND STABLE AIR ALOFT. MOISTURE
INCREASES SLIGHTLY AS A WEAK COLD FRONT MOVES INTO THE AREA ON
SATURDAY. THIS BOUNDARY SHOULD SUPPORT ISOLATED TO SCATTERED
CONVECTION WITH THE BETTER POPS ACROSS THE RANCHLANDS. VERY WARM AND
DRY CONDITIONS RETURN SUNDAY AS WINDS VEER TO THE SOUTHEAST.
MOISTURE SURGES INTO DEEP SOUTH TEXAS EARLY NEXT WEEK AHEAD OF
ANOTHER WEAK COLD FRONT. THE COMBINATION OF THE FRONTAL
BOUNDARY...INCREASING MOISTURE AND FAVORABLE DIFFLUENCE ALOFT WILL
PROVIDE A BETTER OPPORTUNITY OF SHOWERS AND THUNDERSTORMS MONDAY AND
TUESDAY.

MARINE...NOW THROUGH THURSDAY...WITH THE COLD FRONT STALLING NEAR
THE RGV LATER TODAY THE PGF OVER THE LOWER TX BAY AND GULF WATERS
WILL DIMINISH THROUGHOUT TODAY AND TONIGHT ALLOWING FOR FAIRLY CALM
WINDS AND SEAS. A SURFACE LOW IS EXPECTED TO STRENGTHEN OVER NM/W TX
WHICH WILL START STRENGTHENING THE PGF ON THURS POSSIBLY REACHING
SCEC CRITERIA.

THURSDAY NIGHT THROUGH SUNDAY...ADVERSE MARINE CONDITIONS WILL
PREVAIL ALONG THE LOWER TEXAS COAST THURSDAY NIGHT INTO FRIDAY
NIGHT AS LOW PRESSURE DEVELOPS ACROSS WEST TEXAS. EXERCISE CAUTION
CONDITIONS LIKELY WITH SMALL CRAFT ADVISORY CONDITIONS POSSIBLE
THURSDAY NIGHT THROUGH SATURDAY DUE TO ELEVATED WINDS AND SEAS. A
WEAK COLD FRONT IS EXPECTED TO MOVE INTO THE GULF WATERS SATURDAY.
FAVORABLE MARINE CONDITIONS WILL RETURN TO THE LOWER TEXAS COASTAL
WATERS ON SUNDAY.

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

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  87  75  89  78 /  10  10  10   0
BROWNSVILLE          92  74  92  77 /  10  10  10   0
HARLINGEN            93  74  94  78 /   0  10  10   0
MCALLEN              96  74  97  77 /   0  10  10   0
RIO GRANDE CITY     100  72 101  77 /   0  10  10  10
SOUTH PADRE ISLAND   82  75  83  77 /  10  10  10   0

&&

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

$$

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

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