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000
FXUS64 KBRO 201144
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
644 AM CDT MON MAY 20 2013

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

&&

.AVIATION...CURRENT SURFACE OBSERVATIONS AND SATELLITE IMAGERY
INDICATES MVFR CEILINGS PREVAIL ACROSS DEEP SOUTH TEXAS AND THE RIO
GRANDE VALLEY THIS MORNING. VFR CONDITIONS WILL DEVELOP MID TO LATE
THIS MORNING AS SURFACE WINDS INCREASING AND DRIER AIR BEGINS TO
MIXING OUT THE STRATUS. THE STRATUS COULD MIX OUT EARLIER THEN
EXPECTED WITH THE SURFACE INVERSION NARROW. SKIES COULD CLEAR
BEFORE 16Z IF SUFFICIENT MIXING TAKES PLACE. CONFIDENCE IS
MODERATE. WINDS DIMINISHING AROUND SUNSET NEAR THE COAST AND A FEW
HOURS AFTER SUNSET FARTHER WEST WHERE THE STRONGER PRESSURE
GRADIENT PERSIST. STRATUS TO REFORM IN THE EVENING AND OVERNIGHT
WITH MVFR CIGS FIRST AT KBRO AND THEN WORKING WEST AS HAS BEEN THE
CASE THE LAST SEVERAL NIGHTS.


&&

.PREV DISCUSSION... /ISSUED 409 AM CDT MON MAY 20 2013/

SHORT TERM /NOW THROUGH TUESDAY/...A BROAD UPPER TROUGH EXTENDING
ACROSS THE ROCKIES INTO THE NORTHERN PLAINS WILL SLOWLY MOVE EAST
THROUGH TUESDAY. DEEP SOUTH TEXAS AND THE RIO GRANDE VALLEY WILL
REMAIN UNDER THE INFLUENCE OF WEAK 500 MB RIDGING TODAY BEFORE THE
TROUGH AXIS APPROACHES THE REGION ON TUESDAY. MORNING STRATUS CLOUDS
WILL MIX OUT BY MID TO LATE MORNING AS WINDS INCREASE. BREEZY TO
WINDY CONDITIONS EXPECTED TODAY AND TUESDAY AS THE PRESSURE GRADIENT
INCREASES. ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH THE
FORECAST PERIOD WITH HIGH TEMPERATURES RANGING FROM MID 80S ALONG
THE BEACHES...LOW TO MID 90S IN THE RIO GRANDE VALLEY AND IN THE
UPPER 90S TO AROUND 100 IN THE WEST. OVERNIGHT LOW TEMPERATURES
TONIGHT WILL REMAIN IN THE MID TO UPPER 70S. PATCHY HAZE AND SMOKE
FROM THE AGRICULTURAL FIRES IN MEXICO POSSIBLE ACROSS DEEP SOUTH
TEXAS AGAIN TODAY.

LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...A 500 MB SHORT WAVE
MOVING AROUND THE BASE OF THE LARGE CLOSED LOW CENTERED OVER THE
UPPER MIDWEST WILL PUSH OVER CENTRAL AND NORTHERN TX TUES NIGHT
AND WED. THE PASSAGE OF THIS FEATURE WILL MAY INCREASE THE
POTENTIAL FOR SOME ISOLD CONV TO OUR NORTH AND WEST. WILL MAINTAIN
SOME SLGT CHC POPS FOR THESE PERIODS. AFTER THIS SHORT WAVE EXITS
THE REGION TO THE EAST 500 MB RIDGING WILL INCREASE OVER SOUTH TX AS
ANOTHER LARGE 500 MB CLOSED LOW BUILDS SOUTH OVER THE WESTERN
STATES. THIS RIDGING WILL REMAIN ENTRENCHED OVER THE SOUTH CENTRAL
PLAINS STATES AND MEXICO THROUGH NEXT WEEKEND WHICH WILL MAINTAIN
PRETTY ELEVATED 1000-500 MB THICKNESSES THROUGH THE LONG TERM
PERIOD. SO THE ABOVE AVERAGE TEMPS WILL CONTINUE.

THE ECMWF GUIDANCE TRIES TO ADVECT SOME BETTER MOISTURE VALUES UP
AROUND THE WEST SIDE OF THE 700 MB RIDGE AXIS WITH THE BEST VALUES
CONCENTRATED OVER NORTH CENTRAL MEXICO AND WEST AND CENTRAL TX
THROUGH NEXT WEEKEND. THE GFS ALSO REFLECTS THIS GENERAL TREND BUT
DOES NOT SHOW AS STRONG OF MOISTURE ADVECTION. SO SOME DIURNAL AND
OROGRAPHICALLY DRIVEN CONV CAN NOT BE RULED OUT TO OUR WEST AND
NORTH. AM NOT CONFIDENT ENOUGH OF THIS TREND TO INCLUDE ANY BETTER
POPS OUT WEST AND WILL MAINTAIN ONLY SILENT 10 POPS FOR NOW.

AS WITH THE LAST SEVERAL DAYS...THE LONGER RANGE MODEL GUIDANCE
SHOW GOOD OVERALL AGREEMENT IN THE HANDLING OF THE OVERALL
SYNOPTIC FEATURES THROUGH DAY 7. RUN TO RUN AGREEMENT WITH THE MEX
MOS TEMPS AND POPS ARE PRETTY STABLE THROUGH NEXT WEEKEND AND THE
ECMWF TEMPS AND POPS ARE PRETTY CLOSE TO THE MEX GUIDANCE. SO WILL
STICK WITH A BLEND OF THE GFS AND ECMWF NUMBERS THROUGH SUNDAY.

OVERALL CONFIDENCE WITH THE LONGER TERM FORECAST WORDING IS ABOVE
AVERAGE TODAY.

MARINE...
NOW THROUGH TUESDAY...CURRENTLY BUOY020 REPORTS SOUTHEAST WINDS
AROUND 17 KNOTS WITH GUSTS TO 19 KNOTS AND SEAS AROUND 5 FEET. THE
PRESSURE GRADIENT TO REMAIN RATHER TIGHT TODAY WITH MARGINAL SMALL
CRAFT ADVISORY CONDITIONS EXPECTED ACROSS THE BAY WATER.
THEREFORE...HAVE ISSUED A SMALL CRAFT ADVISORY FROM 10 AM THIS
MORNING TO 7 PM THIS EVENING FOR THE LAGUNA MADRE FOR WINDS.
EXERCISE CAUTION CONDITIONS FOR WINDS AND SEAS EXPECTED ON THE GULF
WATERS TODAY. THE WIND FETCH AND LONG DURATION WILL ALLOW BUILDING
SEAS AND SEAS COULD APPROACH 7 FEET AS EARLY AS TONIGHT. ADDITIONAL
SMALL CRAFT ADVISORIES MAY BE REQUIRED FOR EITHER THE LAGUNA MADRE
OR GULF WATERS FOR TONIGHT OR TUESDAY.

TUESDAY NIGHT THROUGH FRIDAY...A MODERATE PGF WILL PREVAIL LATER
THIS WEEK WHICH WILL ALLOW FOR FAIRLY BENIGN MARINE CONDITIONS
ACROSS BOTH THE BAY AND GULF WATERS. NO SCA CONDITIONS EXPECTED
FOR TUESDAY NIGHT AND AFTERWARDS.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  90  78  86  77 /   0   0  10  10
BROWNSVILLE          91  78  90  76 /   0   0  10  10
HARLINGEN            94  77  93  77 /   0   0  10  10
MCALLEN              96  77  95  77 /   0   0  10  20
RIO GRANDE CITY      98  77  99  76 /   0   0  10  20
SOUTH PADRE ISLAND   81  75  85  75 /   0   0  10  10

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY FOR WINDS FROM 10 AM THIS MORNING TO 7 PM
     CDT THIS EVENING FOR GMZ130-132-135.

&&

$$

THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
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