Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 131733 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1233 PM CDT SUN APR 13 2014

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

&&

.AVIATION...DENSE CU FIELD CONTINUES TO ENVELOP MOST OF THE
REGION...AND WILL CONTINUE THROUGH THE REST OF THE DAY. CIGS WILL
HOVER AROUND 3000 FEET...WITH BRIEF LIFTING TO AROUND 4000 JUST
BEFORE SUNSET. CIGS WILL AGAIN LOWER BELOW 1000 FEET
OVERNIGHT...BUT VIS SHOULD REMAIN OK. BREEZY CONDITIONS TODAY WITH
20G30KTS QUITE COMMON. WINDS WILL DECREASE OVERNIGHT WITH
DECOUPLING...REDUCING TO AROUND 10 TO 12 KTS THROUGH THE NIGHT.
MAIN EVENT OCCURS TOMORROW AS THE NEXT COLD FRONT ARRIVES. THE
FRONT IS EXPECTED TO BE ACCOMPANIED BY SCATTER SHOWERS AND
THUNDERSTORMS...AND IS CURRENTLY EXPECTED DURING THE LATER
AFTERNOON. WINDS WILL SHIFT TO THE NORTH BEHIND THE FRONT REACHING
20 KNOTS AT THE SFC.

&&

.PREV DISCUSSION... /ISSUED 641 AM CDT SUN APR 13 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...IR SATL IMAGERY SHOWS TWO CLD LAYERS OVER THE RGV AT THE
MOMENT. SCT TO BKN CIRRUS DECKS CONTINUE TO ADVECT OVER THE AREA
FROM WEST TO EAST. AT THE LOWER LEVELS RAGGED STRATUS DECKS HAVE
BEEN MOVING UP FROM THE SOUTH CAUSING PERIODIC REDUCTIONS TO
CEILINGS FOR ALL OF THE LOWER RGV AIRPORTS OVERNIGHT. EXPECT THE
LOWER CLD DECKS TO CONTINUE PLAGUING THE AREA THROUGHOUT THE EARLY
MORNING HOURS. AFTER SUNRISE THE STRONGER S-SE LOW LEVEL WINDS WILL
MIX DOWN TO THE SURFACE WHICH WILL TEND TO ERODE AWAY THE LOWER
CEILINGS ALLOWING FOR MVFR/VFR CONDITIONS TO RETURN LATER IN THE
MORNING AND CONTINUING INTO THE AFTERNOON HOURS. LOWER CEILINGS WILL
BE EXPECTED ONCE AGAIN LATE IN THE TAF PERIOD AS THE LAYER FROM 950
MB DOWN TO THE SURFACE MOISTENS UP AFTER SUNSET. THIS WILL ALLOW A
RETURN OF MVFR/IFR CEILINGS LATE IN THE PERIOD. HAVE OPTED TO LEAVE
OUT THE MENTION OF LLWS THROUGH THE OVERNIGHT AND EARLY MORNING
HOURS AS BELIEVE THE KBRO VWP IS OVERESTIMATING THE SOUTHERLY WINDS
JUST OFF THE SURFACE.

PREV DISCUSSION... /ISSUED 419 AM CDT SUN APR 13 2014/

SHORT TERM /TODAY THROUGH MONDAY/...THROUGH SUNDAY A SERIES OF 500
MB SHORT WAVES WILL DIG OUT A BROAD TROUGH AXIS OVER THE CENTRAL
PLAINS STATES. AS THIS BROAD TROUGH AXIS DEEPENS OVER THE CENTRAL
STATES A STRONG COLD FRONT WILL DIVE INTO DEEP SOUTH TX ON MONDAY.
THE BEST MOISTURE ADVECTION WILL LIKELY OCCUR JUST AHEAD OF THE
FRONT MAINLY ALONG THE COASTLINE EXTENDING OUT INTO THE GULF OF
MEXICO. COOLER...DRIER AND MORE STABLE AIR WILL THEN MOVE IN BEHIND
THE FRONT LATE MONDAY AFTERNOON INTO MONDAY EVENING QUICKLY ENDING
ANY CONV CHANCES.

SO FOR TODAY AND TONIGHT THE STEADY S-SE LOW LEVEL FLOW WILL
MAINTAIN THE WAA AND MOISTURE FLOW IN OFF OF THE GULF OF MEX WHICH
WILL KEEP PRETTY DECENT CLD COVER AHEAD OF THE FROPA ON MONDAY. AS
THE SURFACE WINDS SLACKEN AND SHIFT A LITTLE MORE TO THE W-SW LATE
IN THE DAY MONDAY EXPECT A LITTLE BETTER POTENTIAL FOR A BIT OF A
HEAT SPIKE ESPECIALLY OVER THE WESTERN COUNTIES.

SO FOR TEMPS HAVE GONE CLOSE TO GUIDANCE CONSENSUS FOR HIGHS TODAY
AND LOWS TONIGHT AND HAVE GONE A LITTLE ABOVE GUIDANCE FOR HIGHS
MONDAY. FOR POPS HAVE LEANED MORE TOWARDS THE SLIGHTLY WETTER ECMWF
NUMBERS. OVERALL QPF AMOUNTS THROUGH THE FROPA MONDAY APPEAR TO BE
PRETTY LOW AS WE WILL HAVE A FAIRLY SMALL WINDOW OF OPPORTUNITY FOR
CONV WITH THE FRONT DUE TO THE SOMEWHAT LIMITED DEEP LAYER MOISTURE
VALUES.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY NIGHT/...THE COLD FRONT
MOVES WELL SOUTH OF THE RIO GRANDE VALLEY MONDAY EVENING. A STRONG
GRADIENT DEVELOPS BEHIND THE FRONT AS SURFACE HIGH PRESSURE SURGES
INTO THE REGION. ELEVATED SHOWERS AND THUNDERSTORMS POSSIBLE MONDAY
NIGHT DUE TO LINGERING MOISTURE AND INSTABILITY ALONG THE COAST.
BREEZY TO WINDY NORTH WINDS EXPECTED TO CONTINUE ACROSS THE AREA
MONDAY NIGHT INTO TUESDAY MORNING DUE TO THE TIGHT PRESSURE
GRADIENT. LOW TEMPERATURES MONDAY NIGHT WILL BE IN THE UPPER 40S
ACROSS THE NORTHERN RANCHLANDS TO THE LOWER 50S NEAR THE COAST. COLD
AIR ADVECTION CONTINUES INTO TUESDAY AFTERNOON WITH HIGH
TEMPERATURES REACHING THE UPPER 60S TO LOWER 70S AS NORTH WINDS
CONTINUE 15 TO 20 MPH.

GOOD RADIATIONAL COOLING EXPECTED ACROSS DEEP SOUTH TEXAS AND THE
RIO GRANDE VALLEY TUESDAY NIGHT AS SURFACE HIGH PRESSURE SETTLES
OVER THE AREA. LOW TEMPERATURES WEDNESDAY MORNING WILL RANGE FROM
THE MID 40S ACROSS THE NORTHERN RANCHLANDS TO THE LOWER 50S IN THE
VALLEY. TEMPERATURES BEGIN TO WARM ON WEDNESDAY AS SURFACE HIGH
PRESSURE MOVES EAST AND WINDS VEER TO THE SOUTHEAST. HIGH
TEMPERATURES WILL CLIMB INTO THE 80S BY THURSDAY AS THE SOUTHEAST
FLOW BECOMES BETTER ESTABLISHED. SURFACE HIGH PRESSURE SURGES BACK
INTO THE REGION BY LATE WEEK RESULTING IN SLIGHTLY COOLER
TEMPERATURES ON SATURDAY.

MARINE...TODAY THROUGH MONDAY...A LIGHT TO MODERATE SE SURFACE FLOW WILL
CONTINUE TODAY AND TONIGHT THROUGH EARLY MONDAY MORNING WHICH WILL
KEEP CONDITIONS BELOW SCA LEVELS DUE THE WARM SE WINDS BLOWING OVER
THE RELATIVELY COOLER BAY AND GULF WATERS. HOWEVER CONDITIONS WILL
BE CHANGING DRASTICALLY LATE MONDAY AS A STRONG PGF BUILDS IN BEHIND
THE COLD FRONT MOVING THROUGH THE REGION. THERE WILL BE A WINDOW OF
SUSTAINED OR GALE FORCE WIND GUSTS ACROSS THE LOWER TEXAS GULF
WATERS FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING. ACCORDINGLY
HAVE POSTED A GALE WATCH FOR THE LOWER TX GULF WATERS STARTING
MONDAY AFTERNOON.

MONDAY NIGHT THROUGH THURSDAY NIGHT...THE PRESSURE GRADIENT WILL
STRENGTHEN MONDAY NIGHT INTO TUESDAY MORNING RESULTING IN POSSIBLE
GALE CONDITIONS FOR PORTIONS OF THE LOWER TEXAS COASTAL WATERS.
STRONG NORTH WINDS CONTINUE THROUGH TUESDAY AFTERNOON BEFORE HIGH
PRESSURE BUILDS ACROSS THE WESTERN GULF TUESDAY NIGHT. THIS WILL
ALLOW FOR IMPROVING MARINE CONDITIONS ALONG THE LOWER TEXAS COAST.
SOUTHEAST WINDS WILL DEVELOP WEDNESDAY INTO THURSDAY.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...GALE WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY AFTERNOON FOR
     GMZ150-155-170-175.

&&

$$

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