Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 141714 AAC
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1214 PM CDT MON APR 14 2014

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

&&

.AVIATION...SHARP COLD FRONT IS MOVING INTO THE NORTHWESTERN
CORNER OF DEEP SOUTH TEXAS AT THIS HOUR. MVFR CIG GENERALLY THE
RULE AHEAD OF THE FRONT AND BEHIND THE FRONT FOR SEVERAL HOURS.
WIND SPEEDS WILL INCREASE SHARPLY WITH SPEEDS OF 20 TO 25 KNOTS
GUSTING TO 35KTS OR BRIEFLY HIGHER AS THE FRONTAL SURGE ARRIVES.
A SHORT LIVED SHIFT TO THE NORTHWEST WITH 8 TO 12 KNOT WINDS LOOKS
TO BE RUNNING AHEAD OF THE MAIN SURGE BY ABOUT AN HOUR. STRONG
WIND WILL PERSIST THROUGH THE AFTERNOON ACROSS THE ENTIRE REGION
AND INTO THE OVERNIGHT HOURS IN CAMERON/WILLACY/KENEDY COUNTIES.
CLOUD DECK WILL DROP TO AROUND 1800 FT IMMEDIATELY BEHIND THE
FRONT BUT VFR CONDITIONS ARE FORECAST BY AROUND 05-07Z AND LASTING
THROUGH THE REMAINDER OF THE TAF PERIOD. LOWER WIND SPEEDS OF 10
TO 15 KNOTS GUSTING TO 20KTS FORECAST FOR TUESDAY AFTER SUNRISE.
/68-JGG/

&&

.PREV DISCUSSION... /ISSUED 1127 AM CDT MON APR 14 2014/

DISCUSSION...BASED ON 11AM OBSERVATIONS AND FORECAST FRONTAL
POSITION UPDATED THE WIND ADVISORY TO BEGIN EARLIER...ESSENTIALLY
NOW IN ZAPATA...JIM HOGG...AND STARR COUNTIES AND EXTENDED IT
THROUGH THE OVERNIGHT IN CAMERON...WILLACY...AND KENEDY COUNTIES.
BUMPED UP WORDING IN THE COASTAL SECTION OF THE ADVISORY TO
INCLUDE WIND GUSTS UP TO 50 MPH LATE THIS AFTERNOON AND EARLY THIS
EVENING. AVAILABLE DATA SUGGESTS A WIND ADVISORY PLUS ONE EVENT
BUT LOWERING MECHANICAL MIXING AFTER SUNSET SHOULD KEEP IT SHY OF
A HIGH WIND WARNING CALIBER EVENT. /68-JGG/

PREV DISCUSSION... /ISSUED 1000 AM CDT MON APR 14 2014/

DISCUSSION...A FEW DIFFERENT ITEMS IN PLAY THIS AFTERNOON AND
EVENING HERE IS THE LATEST THINKING BASED ON PRELIMINARY 12Z DATA.

CONVECTION/THUNDERSTORMS...
12Z SOUNDING SHOWED A VERY STRONG SUBSIDENCE/TERRAIN INDUCED
CAPPING INVERSION AT 800MB. 12Z UPPER AIR ANALYSIS SHOWS TWO
SEPARATE JET MAXIMA OVER TEXAS. ONE A SUBTROPICAL JET OVER
SOUTHERN TEXAS AT ABOUT 110KT AND A SECOND AT 90 TO 110KTS JUST
SOUTH OF THE PANHANDLE REGION ASSOCIATED WITH THE MAIN UPPER LEVEL
TROUGH. THOSE ARE EXPECTED TO ESSENTIALLY MERGE OVER THE NEXT 12
TO 18 HOURS AND MAX UPPER LEVEL WINDS WILL SHIFT TO LA/MS BY
AROUND MIDNIGHT TONIGHT. THE BEST DIFFLUENCE/DIVERGENCE ASSOCIATED
WITH THESE FEATURES RELATIVE TO THE REGION IS ANTICIPATED TO STAY
TO THE NORTH...BUT WEAK DIFFLUENCE IS SUGGESTED BY 06Z GFS/12Z
NAM/RAP GUIDANCE BY LATE THIS AFTERNOON BETWEEN KENEDY COUNTY AND
CORPUS CHRISTI WHICH WILL STEEPEN MID LEVEL LAPSE RATES SOMEWHAT
AND MAINTAIN MODEST ELEVATED INSTABILITY.

IN GENERAL THOUGH THE SHALLOW AND SHARP SURFACE FRONT QUICKLY
UNDERCUTS WELL OUT AHEAD OF THE BEST AVAILABLE UPPER LEVEL ASCENT
AND BELIEVE THAT THE TEMPERATURE INVERSION IS LIKELY TO HOLD UNTIL
AVAILABLE ELEVATED CAPE IS SUBSTANTIALLY LIMITED. THE ELEVATED
NATURE OF THUNDERSTORMS COUPLED WITH HIGH WET BULB ZERO/FREEZING LEVEL
HEIGHTS SHOULD PREVENT LARGE HAIL SHOULD FURTHER LIMIT THE
POTENTIAL FOR LARGE HAIL AND DAMAGING WINDS TODAY...BUT IF THEY
WERE TO OCCUR KENEDY COUNTY SEEMS THE MOST LIKELY CANDIDATE LATE
THIS AFTERNOON AND WILL BE MONITORING THE CONVECTION OVER THE SAN
ANTONIO AREA TO SEE IF FURTHER DEVELOPMENT ALONG AND JUST BEHIND
THE FRONT CONTINUES.

WIND...
THIS SEEMS TO BE DEVELOPING AS A MUCH MORE CLEAR CUT PROBLEM FOR
THE AREA TONIGHT WITH CURRENT STATION PRESSURE AROUND 1006MB AND
GFS AND NAM BOTH SUGGESTING 1028MB BY MIDNIGHT YOU CAN GET THE
PICTURE THAT A SUBSTANTIAL PRESSURE GRADIENT FORCE WILL BE
DEVELOPING IN THE WAKE OF THE FRONT...WHICH IS EVIDENT IN 13/14Z
SURFACE ANALYSIS CHARTS. WITH UPPER CONVERGENCE INCREASING THE
850/925MB WINDS GET A SECONDARY BOOST BY 9 TO 10 PM AND BELIEVE
THAT WINDY...AND LIKELY ADVISORY CONDITIONS WILL PERSIST THROUGH
THE EVENING AND PART OF THE OVERNIGHT IN THE COASTAL COUNTIES.
THIS IS IN ADDITION TO THE AREA WIDE WIND ADVISORY ALREADY IN
EFFECT THIS AFTERNOON AND THIS EVENING. A FEW GUSTS OF 45 TO 50
MPH SEEM LIKELY LATE THIS AFTERNOON AND EVENING ESPECIALLY IN THE
LOWER VALLEY AND CLOSE TO THE COAST. VERY HAZARDOUS MARINE
CONDITIONS WITH THE POSSIBILITY OF AT LEAST A FEW HOURS OF
SUSTAINED GALE FORCE CONDITIONS APPEAR LIKELY AS WELL. /68-JGG/

MARINE...GALE WARNING HAS BEEN UPDATED TO INCLUDE ALL LOWER TEXAS
COASTAL WATERS. SEVERAL HOURS OF FREQUENT GUSTS TO GALE FORCE AND
PERIODS OF SUSTAINED GALE FORCE WINDS ARE EXPECTED THIS AFTERNOON
AND THIS EVENING. /68-JGG/

PREV DISCUSSION... /ISSUED 614 AM CDT MON APR 14 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...A MIX OF IFR/MVFR CONDITIONS WILL PREVAIL ACROSS DEEP
SOUTH TEXAS THIS MORNING. CEILINGS WILL GRADUALLY INCREASE BY MID
MORNING TO MVFR LEVELS. MODERATE AND GUSTY SOUTH WINDS LATER THIS
MORNING WILL SHIFT TO THE NORTH AROUND 20Z AS A STRONG COLD FRONT
MOVES THROUGH THE AREA. SHORT RANGE MODELS SHOW STRONG WINDS BEHIND
THE FRONT WITH GUSTS TO AROUND 33 KNOTS. SHOWERS AND THUNDERSTORMS
POSSIBLE ALONG THE FRONTAL BOUNDARY BUT EXPECTING MOST CONVECTION TO
REMAIN NORTH OF THE TERMINALS. WILL MENTION VCSH AT ALL TAF
LOCATIONS FOR THIS TAF CYCLE. VFR CEILINGS EXPECTED TO DEVELOP AFTER
01Z TUESDAY WITH GUSTY NORTH WINDS CONTINUING AT ALL TERMINALS.
NORTH WINDS GRADUALLY DECREASE LATE TONIGHT.

PREV DISCUSSION... /ISSUED 422 AM CDT MON APR 14 2014/

SHORT TERM /NOW THROUGH TUESDAY/...SURFACE OBSERVATIONS ALONG WITH
WEB CAMERAS ON SOUTH PADRE ISLAND INDICATE PATCHY FOG ALONG THE
LOWER TEXAS COAST THIS MORNING. THE COLD FRONT CURRENTLY LOCATED
FROM THE BEND BIG TO JUNCTION EXTENDING INTO ARKLATEX REGION. THE
FRONT WILL CONTINUE TO RACE SOUTHWARD THIS MORNING. THE COLD FRONT
WILL APPROACH DEEP SOUTH TEXAS THIS AFTERNOON DURING PEAK HEATING.
FRONTAL LIFT ALONG WITH POOLING MOISTURE /BRO SOUNDING FROM SUNDAY
EVENING REVEALS PRECIPITABLE WATER VALUES OF 1.36 INCHES/ WILL
PROVIDE A CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE AREA LATER
TODAY. THE BEST CHANCE OF CONVECTION WILL BE NEAR THE COAST DUE TO
HIGHER INSTABILITY. MOST OF THE DYNAMICS ALOFT WILL BE WELL OFF TO
THE NORTHEAST INTO LOUISIANA AND MISSISSIPPI BY THE TIME THE FRONT
ARRIVES IN THE AFTERNOON. THE FRONT WILL MOVE ACROSS THE NORTHERN
RANCHLANDS AROUND NOON AND THE UPPER VALLEY AROUND 2 PM AND SOUTH OF
THE RIO GRANDE RIVER AROUND 4 PM. RAIN CHANCES BY THIS EVENING AS
DRIER AND COOLER AIR FILTERS INTO THE REGION. STRONG NORTH WINDS
WILL DEVELOP BEHIND THE FRONT DUE TO THE TIGHT PRESSURE GRADIENT.
WINDY CONDITIONS EXPECTED LATER THIS AFTERNOON INTO THIS EVENING
WITH NORTH WINDS AROUND 30 MPH WITH HIGHER GUSTS. TEMPERATURES WILL
FALL INTO THE UPPER 40 TO LOWER 50S TUESDAY MORNING. HIGH
TEMPERATURES ON TUESDAY WILL BE IN THE MID 60S TO LOWER 70S.

LONG TERM.../TUESDAY NIGHT THROUGH SUNDAY/...BROAD 500 MB
TROFFING WILL PREVAIL OVER THE SOUTH CENTRAL PLAINS STATES FROM
TUES NIGHT THROUGH THURSDAY. A FAIRLY STRONG SHORT WAVE MOVING
EAST ACROSS THE CENTRAL U.S. THURS NIGHT AND FRI WILL PUSH A
FAIRLY WEAK COLD FRONT THROUGH DEEP SOUTH TX LATE FRI/EARLY SAT.
A DEEP CLOSED 500 MB LOW WILL FORM ALONG THE WEST COAST OF THE
U.S. WHICH WILL IN TURN HELP BUILD A RIDGE OVER TEXAS NEXT
WEEKEND. OVERALL MOISTURE LEVELS REMAIN PRETTY LIMITED OUT THROUGH
NEXT WEEKEND OVER DEEP SOUTH TX. ALSO THE SERIOUS 500 MB DYNAMICS
WILL LIKELY BE CONFINED WELL NORTH OF THE RGV WHICH WILL LIKELY
KEEP THE PCPN CHCS DOWN FAIRLY LOW.

THE ECMWF IS A LITTLE COOLER WITH TEMPS VERSUS THE GFS THROUGH DAY
7. BELIEVE THAT THE ECMWF IS MAINTAINING TOO COOL OF A BIAS ON THE
TEMPS AND WILL LEAN TOWARDS THE WARMER MEX NUMBERS THROUGH THE
EXTENDED RANGE. RUN TO RUN CONSISTENCY WITH THE MEX TEMPS AND POPS
THROUGH DAY 7 IS PRETTY STABLE. BOTH THE ECMWF AND THE MEX
GUIDANCE ARE IN PRETTY GOOD AGREEMENT WITH POPS. SO OVERALL
CONFIDENCE IN THE LONGER RANGE FORECAST WORDING IS ABOVE AVERAGE.

MARINE...NOW THROUGH TUESDAY...BUOY 42020 REPORTED SOUTHEAST WINDS
OF 12 KNOTS WITH GUSTS OF 14 KNOTS AND SEAS OF 4.6 FEET AT 250
AM/750 UTC. MARINE OBSERVATION PLATFORMS ACROSS THE LAGUNA MADRE
THIS MORNING ARE REPORTING SOUTHEAST WINDS BETWEEN 6 TO 12 KNOTS.
LIGHT TO MODERATE SOUTHEAST WINDS AND PATCHY FOG CAN BE EXPECTED
ACROSS THE MARINE AREA THIS MORNING. A COLD FRONT WILL MOVE ACROSS
THE LOWER TEXAS COAST WATERS THROUGH MID TO LATE AFTERNOON. A
SQUALL LINE WITH GUSTY NORTH WINDS AND OCCASIONAL LIGHTNING MAY
ACCOMPANY THE FRONTAL PASSAGE THIS AFTERNOON.

HAZARDOUS MARINE CONDITIONS WILL DEVELOP ACROSS THE LOWER TEXAS
COASTAL WATERS IN THE WAKE OF THE FRONT. BEHIND THE FRONT...GUSTY
NORTH WINDS OF 25 TO 35 KNOTS WITH HIGHER GUSTS IS EXPECTED OVER THE
GULF WATERS AND NORTH WINDS AROUND 25 KNOTS WITH HIGHER GUSTS ON THE
LAGUNA MADRE. A GALE WARNING REMAINS IN EFFECT FOR THE GULF
WATERS...WITH DEFINITE SMALL CRAFT ADVISORIES FOR THE LAGUNA MADRE
BEGINNING WITH FRONTAL PASSAGE. THERE A POTENTIAL FOR A BRIEF
PERIOD WINDS AROUND GALE FORCE ON THE LAGUNA LATER THIS AFTERNOON
INTO EARLY THIS EVENING. HOWEVER...CONFIDENCE IS BELOW AVERAGE AT
THIS TIME BUT WILL CONTINUE TO MONITOR THIS. BREEZY DUE NORTH WINDS
WILL ALLOW SEAS UP TO 6 TO 10 FEET OFFSHORE BY TONIGHT...INCREASING
TO 10 TO 14 FEET LATE TONIGHT INTO TUESDAY MORNING. ROUGH WATERS CAN
BE EXPECTED ON THE LAGUNA MADRE THROUGH TUESDAY AFTERNOON.

TUESDAY NIGHT THROUGH FRIDAY...A FAIRLY MODERATE E-SE FLOW WILL
PREVAIL THROUGH FRIDAY WITH PRETTY BENIGN SWELLS PERSISTING. THE
APPROACH AND PASSAGE OF THE WEAK FRONT LATE FRI MAY RESULT IN SOME
MODERATE NE SURFACE WINDS. HOWEVER NO SCA CONDITIONS EXPECTED
THROUGH FRI.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...WIND ADVISORY UNTIL 8 PM CDT THIS EVENING FOR TXZ248-249-252.

     WIND ADVISORY UNTIL 6 AM CDT TUESDAY FOR TXZ251-254>257.

     WIND ADVISORY UNTIL 8 PM CDT THIS EVENING FOR TXZ250-253.

GM...GALE WARNING UNTIL 10 AM CDT TUESDAY FOR GMZ130-132-135-150-155-
     170-175.

&&

$$

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