Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 211724 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1224 PM CDT TUE APR 21 2015

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

&&

.AVIATION...OVC DECKS FROM 2 TO 4 KFT PREVAIL WITH LIGHT ONSHORE
WINDS. HIGHER DEWPOINT AIR HAS WORKED BACK NORTH OVER THE AREA...
SATURATING THE BOUNDARY LAYER. LIGHT EAST SOUTHEAST TO SOUTHEAST
WINDS WILL CONTINUE THIS CYCLE...AS WILL OVC SKIES. CEILINGS WILL
LOWER TONIGHT TO MVFR OR IFR. SOME FOG OR HAZE WILL REDUCE VSBY
SLIGHTLY...BUT CEILINGS SHOULD BE THE LIMITING FACTOR. ISOLATED
COASTAL SHOWERS WILL BE POSSIBLE AS A WEAK COASTAL TROUGH
DEVELOPS.

&&

.PREV DISCUSSION... /ISSUED 649 AM CDT TUE APR 21 2015/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...CONDITIONS HAVE IMPROVED ACROSS DEEP SOUTH TEXAS THIS
MORNING. EXPECT MOSTLY VFR CONDITIONS TODAY WITH PERIODS OF MVFR
CONDITIONS IN CONVECTION. MVFR CONDITIONS EXPECTED TO RETURN AT
LOCAL AERODROMES TONIGHT WITH IFR CONDITIONS DEVELOPING AFTER 06Z.

PREV DISCUSSION... /ISSUED 422 AM CDT TUE APR 21 2015/

SHORT TERM /NOW THROUGH WEDNESDAY/...WARM AIR ADVECTION AND
ELEVATED INSTABILITY OVERNIGHT HAS RESULTED IN SOME CONVECTION
ACROSS PORTIONS OF THE RIO GRANDE VALLEY THIS MORNING. LATEST BRO
RADAR SHOWS A NARROW LINE OF SHOWERS WITH EMBEDDED THUNDERSTORMS
MOVING EAST-NORTHEAST ACROSS THE SOUTHERN PORTIONS OF STARR AND
HIDALGO COUNTIES INTO NORTHERN CAMERON. A WARM FRONT WILL MOVE
ACROSS DEEP SOUTH TEXAS LATER TODAY. THE COMBINATION OF INCREASING
DEWPOINTS AND PRECIPITABLE WATERS ALONG WITH LIFT ASSOCIATED WITH A
WARM FRONT WILL RESULT IN A CHANCE OF SHOWERS AND EMBEDDED
THUNDERSTORMS FOR TODAY. THE BEST CHANCE OF CONVECTION WILL BE ALONG
THE RIO GRANDE RIVER AND ACROSS THE RIO GRANDE VALLEY WITH LOWER
CHANCES ACROSS THE NORTHERN RANCHLANDS. A WEAK SHORT WAVE
APPROACHING FROM THE WEST LATE TONIGHT SHOULD SUPPORT A SLIGHT
CHANCE OF POPS TONIGHT INTO WEDNESDAY.

TODAY WILL BE WARM WITH HIGH TEMPERATURES IN THE LOW TO MID 80S
UNDER MOSTLY CLOUDY SKIES. TEMPERATURES TONIGHT WILL NOT BE AS
PLEASANT AS THIS MORNINGS WITH LOW TEMPERATURES TONIGHT BACK INTO
THE 70S. HIGH TEMPERATURES WEDNESDAY WILL RANGE FROM THE LOW 80S
ALONG THE BEACHES...MID TO UPPER 80S ACROSS THE VALLEY AND AROUND 90
ACROSS THE WEST UNDER MOSTLY CLOUDY SKIES.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...A PRETTY STRONG 500
MB TROUGH WILL BE DIGGING EAST ACROSS THE SOUTHWESTERN STATES WED
NIGHT INTO THURS. THIS TROUGH WILL MOVE OVER THE TX/OK PANHANDLE
REGION ON FRI EVENTUALLY MOVING INTO THE MID MISS RIVER VALLEY BY
SAT. THIS TROUGH WILL THEN BE FOLLOWED PRETTY QUICKLY BY A 2ND
TROUGH WHICH WILL PUSH INTO TX SUN AND MON. FAIRLY DECENT DEEP
LAYER MOISTURE VALUES WILL ACCOMPANY THE FIRST OF THESE TROUGHS
AND WILL THEN BE MORE LIMITED WITH THE APPROACH AND PASSAGE OF
THE 2ND TROUGH. AS THE FIRST TROUGH RIDES UP AND OVER THE SHALLOW
500 MB RIDGING THAT WILL BE LOCATED OVER THE GULF OF MEX AND THE
TX COASTLINE THE BEST DIVERGENCE ALOFT WILL LIKELY BE LOCATED TO
THE NORTH AND WEST OF DEEP SOUTH TX. SO WILL ALIGN THE LONGER
RANGE POPS TO FAVOR THE WESTERN AND NORTHERN COUNTIES OF THE BRO
CWA FOR THE MOST PART. WITH THE 2ND TROUGH WILL FAVOR ONLY SLGT
CHC POPS AT THIS TIME DUE TO THE MORE LIMITED MOISTURE VALUES
POOLING AHEAD OF THE FEATURE.

1000-500 MB THICKNESS VALUES REMAIN PRETTY ELEVATED THROUGH THE
ENTIRE LONGER TERM PERIOD WHICH WILL TEND TO HOLD UP THE OVERALL
TEMPS WELL ABOVE CLIMO FOR LATE APRIL. WILL FAVOR THE SLIGHTLY
WARMER ECMWF TEMP GUIDANCE THROUGH DAY 7. WILL GO WITH A GENERAL
MODEL BLEND FOR POPS IN THE LONGER RANGE PERIOD.

MARINE...NOW THROUGH WEDNESDAY...LIGHT EAST WINDS ALONG THE LOWER
TEXAS COAST THIS MORNING WILL GRADUALLY TURN TO THE SOUTHEAST LATER
TODAY. SURFACE HIGH PRESSURE BUILDS OVER THE NORTH CENTRAL GULF OF
MEXICO THROUGH MID WEEK. THIS WILL RESULT IN MODERATE WINDS AND SEAS
THROUGH THE PERIOD.

WEDNESDAY NIGHT THROUGH SATURDAY...MODERATE SURFACE RIDGING WILL
PREVAIL OVER THE WESTERN GULF OF MEX THROUGH THE END OF THE WEEK
AND INTO THE WEEKEND WHICH WILL MAINTAIN FAIRLY WEAK TO MODERATE
ONSHORE FLOW ALONG THE LOWER TX COASTLINE. NO SCA CONDITIONS
EXPECTED THROUGH SATURDAY.

&&

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

$$

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