Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 180539 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1239 AM CDT FRI APR 18 2014

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

.AVIATION...THE LIGHT PRECIPITATION HAS ENDED WITHIN DEEP SOUTH
TEXAS AND THE RIO GRANDE VALLEY AND CORRESPONDINGLY...CEILINGS
HAVE RISEN TO BETWEEN 1000 AND 1500 FEET...WITH LIGHT WINDS IN
PLACE. VFR WILL RETURN ON FRIDAY WITH HIGHER CEILINGS AND MODERATE
WINDS THAT WILL BECOME LIGHTER IN THE LATE EVENING.
&&

.PREV DISCUSSION... /ISSUED 725 PM CDT THU APR 17 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...CEILINGS ARE FALLING FASTER THAN EXPECTED AND NEW DATA
FROM THE EVENING BALLOON SHOWS HIGHER LOW LEVEL RELATIVE HUMIDITY
THAN EXPECTED SO HAVE AMENDED THE TAFS TO BE MORE PESSIMISTIC THAN
THE ORIGINAL 00Z PACKAGE NOW FORECASTING LIFR IN A FEW HOURS AT
HRL/BRO WITH IFR IN THE MEANTIME. IT MAY TAKE ANOTHER HOUR OR TWO
FOR THE IFR TO FULLY SETTLE IN OVER THE REGION BUT A WEAK
INVERSION AT AROUND 900 FT SHOULD HELP HOLD IT IN PLACE. /68-JGG/

PREV DISCUSSION... /ISSUED 624 PM CDT THU APR 17 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...WEAK COASTAL TROUGHING HAS ESTABLISHED OVER THE AREA
HELPING KEEP AN MVFR CLOUD DECK AND PERIODIC SPRINKLES IN PLACE.
WITH RELATIVELY WEAK ONSHORE FLOW EXPECT CIG TO DROP THROUGH THE
EVENING TO IFR...MOISTURE PROFILES DO NOT QUITE SUPPORT A LIFR
FORECAST BUT CANNOT COMPLETELY RULE IT OUT BY SUNRISE TONIGHT. A
GRADUAL IMPROVEMENT TO MVFR IS FORECAST BY MID MORNING AND CLOUD
DECKS MAY RISE ABOVE 3000 FT BY MID TO LATE AFTERNOON FRIDAY.
WINDS WILL BE OUT OF THE EAST TO NORTHEAST AT ABOUT 7 TO 12 KNOTS.
/68-JGG/

PREV DISCUSSION... /ISSUED 143 PM CDT THU APR 17 2014/

SHORT TERM /NOW THROUGH FRIDAY NIGHT/...HIGH PRESSURE WILL
FILTER SOUTH INTO THE AREA TONIGHT...PROVIDING A BRIEF DRYING
TREND THROUGH 36 HOURS...WITH PWAT DECREASING TO AROUND AN INCH
FROM THE CURRENT INCH AND A HALF. A WEAK H5 RIDGE WILL MOVE
OVERHEAD THROUGH FRIDAY AND THE CAP WILL ERODE BUT NOT DISAPPEAR
COMPLETELY. LOWS IN THE 60S TONIGHT WILL BECOME UPPER 70S TO LOWER
80S ON FRIDAY. FARTHER TO THE WEST...A MID LEVEL TROUGH WILL MOVE
OVER SOUTHERN CALIFORNIA FROM THE EASTERN PACIFIC TONIGHT. MID
LEVEL FLOW WILL BECOME SOUTHWEST FRIDAY TO FRIDAY NIGHT AND
PACIFIC MOISTURE WILL RESULT IN TSTMS OVER THE MEXICAN MOUNTAINS
FRIDAY NIGHT. THE TROUGH AXIS MAY NOT DIG FAR ENOUGH SOUTH TO PUSH
TSTMS INTO THE RGV...BUT CONVECTION LOOKS LIKELY FARTHER NORTH
OVER THE RIO GRANDE PLAINS. LOW TEMPS FRIDAY NIGHT WILL BE IN THE
MID 60S ONCE AGAIN. KEPT AN ONGOING MENTION OF GENERAL ISOLATED
SHOWERS IN THE FORECAST THROUGH THE SHORT TERM. THE PATTERN ALOFT
IS PROGRESSIVE ENOUGH AND SUPPORTED SOMEWHAT BY THE SUBTROPICAL
JET SUCH THAT A SLIGHTLY UNSETTLED PATTERN WILL BE THE RULE.

LONG TERM /SATURDAY THROUGH THURSDAY/...THE H5 RIDGE WILL BE
EXITING THE REGION ON SATURDAY...WITH THE NEXT TROUGH APPROACHING
FOR THE WEEKEND. AT THE SFC...HIGH PRESSURE WILL BE SETTLING
ACROSS THE GULF OF MEXICO...RETURNING WINDS TO THE SOUTHEAST
SATURDAY MORNING. THIS WILL BEGIN TO INCREASE LLVL MOISTURE IN THE
REGION. THE PEAK OF THE INSTABILITY FROM THE H5 TROUGH WILL ARRIVE
ON SUNDAY MORNING...AND WILL ATTEMPT TO TAP SOME OF THIS MOISTURE.
THIS WILL LEAD TO A FEW SHOWER IN THE VICINITY SUNDAY. THESE WILL
NOT BE AN ALL DAY EVENT...MORE OF A SPLASH AND DASH SHOWER. THIS
MIDLEVEL TROUGH WEAKENS AND DRIFTS EAST EARLY NEXT WEEK...WITH
STRONGER RIDGING ARRIVING. THIS WILL KEEP ANY IMPULSES WELL AWAY
FROM THE REGION. AT THE SFC...SOUTHEAST FLOW CONTINUES TO BRING
MOISTURE INTO THE REGION...AND WILL HELP TEMPERATURES INCREASE
SLOWLY EACH DAY INTO THE UPPER 80S. NO RAIN CHANCES ARE EXPECTED
UNTIL MAYBE THE END OF NEXT WEEK.

MARINE...
NOW THROUGH FRIDAY NIGHT...LIGHT TO MODERATE WINDS WILL CONTINUE...
BUT WILL BACK SLIGHTLY TO EAST NORTHEAST AS HIGH PRESSURE FILTERS IN
OVER THE NORTHWEST GULF FROM THE NORTH. WAVE HEIGHTS WILL CONTINUE
IN THE MODERATE RANGE...BUT COULD MEET EXERCISE CAUTION CRITERIA AT
TIMES. ISOLATED SHOWERS WILL BE ON AGAIN OFF AGAIN TONIGHT BUT WILL
TAPER OFF ON FRIDAY.

SATURDAY THROUGH MONDAY...MODEST SOUTHEAST WINDS WILL CONTINUE ON
SATURDAY 10 TO 15 KNOTS CREATING SEAS OF 3 TO 4 FEET. LOW PRESSURE
DEVELOPING IN THE CENTRAL PLAINS WILL TIGHTEN THE GRADIENT
SATURDAY NIGHT INTO SUNDAY...INCREASING WINDS TO 15 TO 20
KNOTS...WHICH WILL GRADUALLY INCREASE SEAS TO 4 TO 5 FEET. THE
AREA OF LOW PRESSURE MOVES TO THE NE SUNDAY NIGHT...ALLOWING WINDS
TO RELAX INTO MONDAY BACK DOWN TO AROUND 10 KNOTS. NOT EXPECTING
ANY ADVISORIES FOR THE WEEKEND...BUT SOME CAUTION MAY BEEN URGED
FOR THE DAY SUNDAY.
&&

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

$$

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