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000
FXUS64 KBRO 121736
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1236 PM CDT SUN MAY 12 2013

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

&&

.AVIATION...ABUNDANT CLOUD COVER AT AROUND 3 TO 5KFT IS SPREAD
ACROSS SOUTH TEXAS AT THIS TIME WITH LIGHT NORTHERLY WINDS. THESE
CLOUDS WILL BEGIN TO BREAK THIS AFTERNOON AND WINDS WILL PICK UP A
LITTLE BIT SHIFTING SLOWLY TO THE NORTHEAST. A CHANCE OF A FEW
SHOWERS DEVELOPING IS EXPECT THIS LATE AFTERNOON. INTO TONIGHT...
LIGHT AND CALM WINDS WILL PREVAIL THROUGH THE NIGHT WITH MVFR
CONDITIONS AND POSSIBLE SHOWER ACTIVITY ESPECIALLY OVER THE
WESTERN PORTION OF THE CWA. EARLY MONDAY WINDS WILL GRADUALLY
INCREASE AND SHIFT TO THE EAST.


&&

.PREV DISCUSSION... /ISSUED 621 AM CDT SUN MAY 12 2013/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...MORNING CONVECTION ACROSS SOUTH TEXAS TO TAPPER OFF
MID TO LATE MORNING THEN REDEVELOP LATE THIS AFTERNOON AND TONIGHT.
SKIES TO REMAIN CLOUDY WITH CIGS VARYING BETWEEN VFR AND MVFR WITH
MORE PERSISTENT MVFR TO IFR IN SHOWERS AND ISOLATED THUNDERSTORMS.
AS OF 6 AM A BAND OF SHOWERS IS DEVELOPING ALONG BOUNDARY FROM
PORT MANSFIELD TO NORTH OF HARLINGEN TO MCALLEN. LITTLE MOVEMENT
OF THE LINE OF SHOWERS IS NOTED.

PREV DISCUSSION... /ISSUED 340 AM CDT SUN MAY 12 2013/

SHORT TERM /NOW THROUGH MONDAY/...THE LARGE 500MB UPPER
TROUGH/LOW TO REMAIN NEARLY STATIONARY OR EVEN RETROGRADE SLIGHTLY
SOUTHWEST ACROSS NORTHWEST MEXICO THROUGH MONDAY. NORTHEASTERN
MEXICO AND DEEP SOUTH TEXAS REMAINS IN THE FAVORED MID TO UPPER
SOUTHWEST DIFFLUENT FLOW WITH A MOIST NORTHEAST TO EASTERLY FLOW
AT THE SURFACE TO KEEP A CHANCE OF SHOWERS AND THUNDERSTORMS IN
THE FORECAST. THE NE-E FLOW COUPLED WITH THE SW-W FLOW ALOFT WILL
MAINTAIN A WEAK BUT SUFFICIENT OVERRUNNING REGIME THROUGH MONDAY.
IT REMAINS DIFFICULT TO TIME THE UPPER DISTURBANCES AND JET MAXES
THAT ARE EXPECTED TO ROTATE AROUND THE UPPER TROUGH AND INITIATE
THE CONVECTION. NOCTURNAL CONVECTION HAS BEEN THE TREND THE LAST
TWO NIGHTS WITH THE GFS DOING AN EXCELLENT JOB ON THE PINPOINTING
DISTURBANCES RATHER WELL. MODELS CONTINUE TO TREND WITH HIGH END
CHANCE TODAY DROPPING OFF SLIGHTLY TONIGHT AND INCREASING DURING
THE DAY. OUR THINKING HERE IS TO MAINTAIN A PERSISTENT CHANCE OF
RAIN THROUGH THE PERIOD WITH LITTLE CHANGE IN THE OVERALL PATTERN.
CONVECTION COULD TAPPER OFF RATHER QUICKLY THIS MORNING AND MAY
WAIT UNTIL INITIATION OVER THE MEXICAN PLATEAU TONIGHT WITH THE
GFS INDICATING THE NEXT WAVE MOVING INTO THE WESTERN HALF OF THE
CWA OVERNIGHT. WILL MAINTAIN A CHANCE OF RAIN TODAY BUT DO NOT
EXPECT ANY TYPE OF WASH OUT FOR ANY MOTHERS DAY OUTING BUT KEEP AN
UMBRELLA HANDY. HEAVIER QPF VALUES WILL BE SPOTTY WITH SOME
ISOLATED HEAVY RAIN WITH THUNDER. HIGH TEMPERATURES TO REMAIN JUST
BELOW GUIDANCE TODAY AND MONDAY WITH MOSTLY CLOUDY SKIES AND THE
CHANCE OF RAIN LINGERING.

LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...LONG TERM PERIOD
STARTS WITH UPPER LOW OVER BAJA CALIFORNIA AND UPPER HIGH OVER THE
YUCATAN. DIFFLUENT FLOW WITH MINOR SHORTWAVES EJECTING FROM UPPER
LOW WILL LEAD TO CONTINUED THUNDERSTORM CHANCES MONDAY NIGHT INTO
TUESDAY...WILL BE LOOKING AT UPSLOPE THUNDERSTORMS FORMING OVER
THE HIGHER TERRAIN OF MEXICO AND MOVE INTO THE AREA. AS A JET
STREAK ROUNDS THE BASE OF THE UPPER TROUGH...THE LOW WILL OPEN UP
AND MOVE INTO THE SOUTHERN PLAINS WEDNESDAY AND POINTS EASTWARD
THURSDAY. PRECIPITATION CHANCES DECREASE AS THIS FEATURE PULLS
AWAY WITH THE FORECAST DRY FROM WEDNESDAY THROUGH SUNDAY WITH UPPER
RIDGING BUILDING IN. TEMPERATURES WILL INCREASE DURING THIS PERIOD
AND CONTINUED THE TREND OF STAYING ON THE WARM SIDE OF GUIDANCE
WITH READINGS APPROACHING THE CENTURY MARK IN THE UPPER VALLEY FOR
MAXES SATURDAY. A SHORTWAVE TROUGH COMES ASHORE THE NORTHWESTERN
CONUS THURSDAY WHICH WILL LEAD TO DEVELOPING SURFACE LEE TROUGHING
AND WINDS PICKING UP FROM THE SOUTHEAST BEGINNING THURSDAY.

MARINE /NOW THROUGH MONDAY/...A LIGHT TO MODERATE EASTERLY WIND
REGIME TO PERSIST THROUGH MONDAY AS SURFACE HIGH PRESSURE EXTENDS
ACROSS THE NORTHERN GULF AND UPPER LOW PRESSURE REMAINS ANCHORED
OVER NORTHERN MEXICO. A LOW TO MODEST SEA IS EXPECTED WITH THE
SWELL PERIOD LENGTHENING THROUGH MONDAY AS THE EAST FLOW OVER THE
NORTHERN GULF CONTINUES. THERE WILL REMAIN A CHANCE OF SHOWERS AND
THUNDERSTORMS THROUGH MONDAY.

MONDAY NIGHT THROUGH FRIDAY...
EASTERLY WINDS WILL CONTINUE INTO TUESDAY WITH SURFACE HIGH PRESSURE
CENTERED OVER THE SOUTHEAST CONUS. AS HIGH PRESSURE MOVES TO THE
EAST...SOUTHEASTERLY WINDS WILL RETURN BEGINNING TUESDAY NIGHT.
SPEEDS WILL LIKELY INCREASE BEGINNING WEDNESDAY AS LOW PRESSURE
DEVELOPS OVER THE HIGH PLAINS AND THE PRESSURE GRADIENT BECOMES
STRONGER. EXERCISE CAUTION OR LOW END SMALL CRAFT ADVISORIES WILL BE
POSSIBLE AT TIMES WEDNESDAY THROUGH FRIDAY. SEAS WILL ALSO BUILD
TOWARD THE LATTER HALF OF THE WORK WEEK AS WIND SPEEDS INCREASE AS
WELL.

&&

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

$$

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