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000
FXUS64 KBRO 212348
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
648 PM CDT TUE MAY 21 2013

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

&&

.AVIATION...SHOWERS/THUNDERSTORMS DEVELOPING OVER THE HIGHER
TERRAIN OF THE SIERRA MADRE MOUNTAINS TO OUR WEST IN NORTHERN
MEXICO WITH HIGH LEVEL CIRRUS FROM THESE STORMS MOVING OVER DEEP
SOUTH TEXAS ATTM. DUE TO A MORE HOSTILE ENVIRONMENT...EXPECT
TSTORMS TO WEAKEN/DISSIPATE BEFORE MAKING IT INTO THE AREA.
OTHERWISE...EXPECT MVFR CIGS TO DEVELOP OVER THE NEXT FEW HOURS AT
KBRO/KHRL AND A LITTLE LATER AT KMFE. MUCH LIKE THE LAST SEVERAL
EVENINGS...EXPECT CIGS AROUND 015 WITH A SLIGHT REDUCTION IN VIS
AS WELL FROM TIME TO TIME. BASED ON PERSISTENCE...CIGS SHOULD
LIFT/SCATTER OUT WITH VFR CONDS RETURNING BY MID MORNING
WEDNESDAY. WINDS WILL CONTINUE FROM THE SOUTHEAST THIS PERIOD WITH
SPEEDS NOT AS STRONG AS THE LAST SEVERAL DAYS...A FEW PEAK GUSTS
TO 20KTS POSSIBLE ESPECIALLY IN THE EARLY AFTERNOON HOURS.

&&

.PREV DISCUSSION... /ISSUED 141 PM CDT TUE MAY 21 2013/

SHORT TERM /NOW THROUGH WEDNESDAY NIGHT/...MODEL ANALYSIS OF ANY
POTENTIAL THUNDERSTORM ACTIVITY IN BROWNSVILLE CWA REMAINS VERY
LOW. INGREDIENTS ARE NOT CONDUCIVE FOR SIGNIFICANT OR SUSTAINABLE
CONVECTION IN THE REGION TONIGHT. MOISTURE REMAINS VERY
SHALLOW...THE INSTABILITY ALTHOUGH SUFFICIENTLY HIGH THE
CONVECTIVE INHIBITION OR CAP REMAINS RATHER STRONG. ALSO THE
BETTER DIVERGENT FLOW AND JET FEATURES REMAIN WELL NORTH OF THE
RGV IN ASSOCIATION WITH THE MAIN UPPER TROUGH. THERE REMAINS A LOW
PROBABILITY OF THUNDERSTORMS THAT FORM ALONG A PREFRONTAL SURFACE
TROUGH OVER WEST CENTRAL TEXAS THIS AFTERNOON TO DRIFT SOUTHEAST
WITH THE MEAN FLOW AND AFFECT THE NORTHWEST ZONES OF ZAPATA AND
JIM HOGG. AS MENTIONED YESTERDAY WITH THE ATMOSPHERE NOT CONDUCIVE
TO SUSTAIN CONVECTION ANY STORMS THAT APPROACH THE AREA WILL
LIKELY BE ON THEIR LAST LEGS. WILL MAINTAIN THE LOW 20 PERCENT
CHANCES FOR ANY ISOLATED STORM THAT MIGHT REACH THESE ZONES.

OTHERWISE...THE UPPER TROUGH TO CONTINUE TO LIFT NORTHEAST WITH THE
MID LEVEL UPPER RIDGE TO GRADUALLY BUILD IN FROM THE WEST.
PERSISTENCE REMAINS THE BEST FORECAST WITH MOSTLY CLOUDY NIGHTS AND
MORNING WITH MOSTLY SUNNY TO PARTLY CLOUDY AFTERNOON. THE STRONGEST
OF WINDS TO DROP OFF BY WEDNESDAY WITH THE PRESSURE GRADIENT
RELAXING AS HIGH PRESSURE REPLACES LOW PRESSURE OVER THE STATE.
TEMPERATURES REMAIN AT OR SLIGHTLY ABOVE SEASONAL NORMALS WITH
OVERNIGHT LOWS BY THURSDAY MORNING DROPPING A FEW DEGREES AS LIGHTER
WINDS ALLOW FOR SOME ADDITIONAL COOLING BUT JUST A LITTLE.

LONG TERM /THURSDAY THROUGH MEMORIAL DAY/...HIGH AMPLITUDE
PATTERN REMAINS GENERALLY STATIONARY FOR THE EXTENDED
PERIOD...WITH H5 RIDGING BUILDING ACROSS THE CENTRAL US BOOKENDED
BY TROUGHS ALONG THE EAST AND WEST COASTS. THIS WILL GENERALLY
STEER ANY IMPULSES WELL TO OUR NORTH AND KEEPING THE GENERALLY DRY
AIR ALOFT IN PLACE THROUGH EARLY NEXT WEEK. AT THE SFC....GULF
MOISTURE AND HAZE FROM FIRES WELL TO THE SOUTH WILL CONTINUE TO
OVERSPREAD THE LOWEST LEVELS...BRINGING HAZY CONDITIONS DURING THE
DAY AND LOW CLOUD COVER EACH NIGHT. MODELS ARE HINTING AT A WEAK
IMPULSE ALOFT MOVING SOMEWHAT CLOSE TO THE REGION AROUND THE RIDGE
FRIDAY OR SATURDAY...BUT TIMING AND LOCATION ARE STILL NOT WELL
DEFINED BY MODELS...AND STRONG CAPPING WOULD INHIBIT ANY
CONVECTION FROM APPROACHING FRO THE MOUNTAINOUS REGIONS TO THE
WEST. INSTEAD THIS WILL MAINLY PROVIDE THICKER CIRRUS SHIELD OVER
THE WEEKEND. MODEL DIVERGE ON THE FINAL RESULT OF THE RIDGING
MONDAY INTO TUESDAY...SO WILL NOT CHANGE ONGOING LONG RANGE
FORECAST.

MARINE...
NOW THROUGH WEDNESDAY NIGHT...WINDS HAVE BEEN NOT AS STRONG THIS
EARLY AFTERNOON ON THE LAGUNA AND WITH THE PRESSURE GRADIENT
PEAKING YESTERDAY WILL GO AND CANCEL THE SMALL CRAFT ADVISORY.
EXERCISE CAUTION WILL BE VALID AS WINDS AND SEAS WILL BE AT
MARGINAL SCA LEVELS THE REST OF TODAY AND INTO THE EVENING
OFFSHORE. MODERATE SOUTHEAST FLOW TO PERSIST WEDNESDAY AS HIGH
PRESSURE REPLACES THE LOWER PRESSURE OVER THE STATE AND BROAD HIGH
PRESSURE OVER THE GULF CONTINUES.

THURSDAY THROUGH SUNDAY...CONSISTENT SOUTHEAST FLOW CONTINUES
THROUGH THE WEEKEND WITH HIGH PRESSURE DOMINATING THE GULF AND
LACK OF OPPOSING LOW PRESSURE AREA TO THE WEST. SOUTHEAST WINDS
WILL GENERALLY RUN 10 TO 15 KNOTS THROUGH SUNDAY...WHICH WILL
PROVIDE SEAS OF 3 TO 4 OFFSHORE AND MODERATE CHOPPINESS ON THE
LAGUNA.

&&

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

$$

THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WEATHER.GOV/RGV

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