000
FXUS64 KBRO 211724
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1224 PM CDT TUE MAY 21 2013

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

&&

.AVIATION...MVFR STRATUS STEADILY BREAKING UP AND LIFTING AS
DAYTIME MIXING COMMENCES. CU FIELD TO CONTINUE TO SHRINK BUT
RESIDUAL SCT-BKN TO CONTINUE ACROSS MOST AREAS THROUGH AT LEAST
20Z WITH THE COASTAL SECTIONS SEEING THE MOST CLEARING. STRATUS IS
EXPECTED TO REBUILD ONCE AGAIN A FEW HOURS AFTER SUNSET IN THE
VICINITY OF KBRO AND KHRL THE SPREAD NORTHWEST THE REMAINDER OF
THE NIGHT. SURFACE WIND GUSTS OF 25 TO 30 KNOTS TO CONTINUE THIS
AFTERNOON THEN DIMINISH AROUND OR AFTER SUNSET.

&&

.PREV DISCUSSION... /ISSUED 633 AM CDT TUE MAY 21 2013/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...MVFR CEILINGS AND MODERATE SOUTHEAST WINDS PREVAIL
ACROSS DEEP SOUTH TEXAS AND THE RIO GRANDE VALLEY THIS MORNING. VFR
CONDITIONS WILL DEVELOP BY MID TO LATE THIS MORNING WITH BREEZY TO
WINDY CONDITIONS. WINDS WILL BEGIN TO DECREASE AFTER SUNSET THIS
EVENING WITH LOW CLOUDS RETURNING LATER TONIGHT. LOW LEVEL JET IS
30 TO 35 KNOTS BETWEEN 2000-4000 FEET PER 12Z SOUNDING. THIS
SHOULD TRANSLATE TO THE SURFACE WITH SOUTHEAST SURFACE
WINDS GUSTING TO AT LEAST 30 KNOTS MID TO LATE MORNING AND INTO
THE AFTERNOON.

PREV DISCUSSION... /ISSUED 443 AM CDT TUE MAY 21 2013/

SHORT TERM NOW THROUGH WEDNESDAY/...500 MB TROUGH WILL CONTINUE TO
MOVE SLOWLY EASTWARD TODAY. SURFACE LOW PRESSURE OVER NORTHERN TEXAS
WILL INTERACT WITH HIGH PRESSURE OVER THE GULF OF MEXICO TODAY.
RESULTING IN BREEZY TO WINDY CONDITIONS LATER THIS MORNING INTO THE
AFTERNOON WITH GUSTS AROUND 30 MPH. HIGH TEMPERATURES TODAY WILL BE
IN THE LOW TO MID 80S NEAR THE COAST...LOW TO MID 90S ACROSS THE
VALLEY AND UPPER 90S TO AROUND 100 WEST. AN UPPER LEVEL DISTURBANCE
WILL MOVE ACROSS THE REGION TONIGHT. THIS FEATURE COULD TRIGGER A
FEW STORMS THIS EVENING AND MOVE TOWARDS THE RIO GRANDE RIVER LATER
TONIGHT. CONFIDENCE REMAINS LOW BUT WILL MAINTAIN THE LOW POPS FOR
TONIGHT OVER THE NORTHWEST. OVERNIGHT LOW TEMPERATURES TONIGHT WILL
REMAIN IN THE MID TO UPPER 70S. HIGH TEMPERATURES WEDNESDAY WILL BE
IN THE 90S...EXCEPT FOR THE LOW TO MID 80S NEAR THE COAST.

LONG TERM...WEDNESDAY NIGHT THROUGH MEMORIAL DAY...A PAIR OF 500
MB TROUGH/CLOSED LOWS OVER THE PACIFIC NW AND THE GREAT LAKES
REGIONS WILL BUILD RIDGING OVER THE CENTRAL PORTION OF THE COUNTRY
AND MEXICO LATE WED INTO THURS. THIS RIDGING WILL REMAIN IN PLACE
FOR THE MOST PART THROUGHOUT THIS WEEK THROUGH MEMORIAL DAY WHICH
WILL MAINTAIN THE SUMMERLIKE PATTERN OVER DEEP SOUTH TX. THE RIDGE
MAY BREAK DOWN SOMEWHAT AS THE WEEKEND APPROACHES AS SOME SHORT
WAVES MOVE OVER THE TOP OF THE RIDGE. THIS WOULD LEND SOME HOPE TO
SOME BETTER CONV CHCS LATE IN THE FORECAST PERIOD. HOWEVER THE
MAIN PROBLEM APPEARS TO BE LACKING MOISTURE LEVELS AND INSTABILITY
ANTICIPATED OVER THE REGION. BOTH THE GFS AND ECMWF TRY TO ADVECT
SOME BETTER MOISTURE UP AROUND THE WEST AND NORTH SIDE OF THE 700
MB RIDGE AXIS STARTING THIS COMING FRIDAY INTO THE UPCOMING
WEEKEND. BUT THE MAIN MOISTURE AND INSTABILITY AXIS APPEARS TO
REMAIN LOCATED TOO FAR TO THE WEST OF DEEP SOUTH TX TO HAVE MUCH
ON AN IMPACT OVER THE REGION. THE DIURNAL HEATING AND OROGRAPHIC
EFFECTS MAY FIRE OFF SOME AFTERNOON AND EVENING CONV OVER
NORTHEAST MEXICO AND SOUTH CENTRAL TX BUT AM NOT VERY CONFIDENT
THAT THIS ACTIVITY WILL LAST LONG ENOUGH TO MOVE INTO DEEP SOUTH
TX. SO WILL NOT INCREASE POPS ANY IN THE LONGER RANGE PERIOD AND
WILL MAINTAIN ONLY SILENT 10 % POPS AT THIS TIME.

THE LONGER RANGE GFS/ECMWF AND CMC GUIDANCE MAINTAINS GOOD OVERALL
AGREEMENT IN THE SYNOPTIC PATTERN THROUGH NEXT MONDAY. RUN TO RUN
AGREEMENT WITH THE MEX MOS TEMPS/POPS AND THE ECMWF NUMBERS REMAIN
IN GOOD AGREEMENT. SO WILL MAINTAIN LONGER RANGE TEMPS AND POPS
PRETTY CLOSE TO A GFS/ECMWF CONSENSUS.

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

MARINE...
NOW THROUGH WEDNESDAY...THE PRESSURE GRADIENT IS EXPECTED TO
INCREASE LATER TODAY AS HIGH PRESSURE OVER THE GULF INTERACTS WITH
LOW PRESSURE OVER NORTHERN TEXAS. SURFACE OBSERVATIONS ALONG THE
LAGUNA MADRE THIS MORNING HAVE BEEN INCREASED ESPECIALLY OVER MID
AND NORTHERN PORTIONS OF THE BAY. THEREFORE...HAVE ISSUED A SMALL
CRAFT ADVISORY FOR THE LAGUNA MADRE THROUGH 8 PM THIS EVENING.
CURRENTLY BUOY020 REPORTS SOUTHEAST WINDS AROUND 16 KNOTS WITH GUSTS
TO 18 KNOTS AND SEAS JUST UNDER 5 FEET. WILL ALLOW THE SMALL CRAFT
ADVISORY CURRENTLY IN EFFECT FOR THE GULF WATERS TO CONTINUE AS
MARGINAL SMALL CRAFT CONDITIONS STILL POSSIBLE. MODERATE SOUTHEAST
WINDS TO PREVAIL TONIGHT AND WEDNESDAY AS THE PRESSURE GRADIENT
RELAXES ACROSS THE LOWER TEXAS COASTAL WATERS.

WEDNESDAY NIGHT THROUGH SATURDAY...A SERIES OF BROAD SURFACE
RIDGES OVER THE SOUTHEASTERN STATES AND THE GULF OF MEXICO WILL
MAINTAIN A MODERATE PGF LATER THIS WEEK. THIS WILL ALLOW FOR
FAIRLY BENIGN MARINE CONDITIONS ACROSS BOTH THE BAY AND GULF
WATERS. NO SCA CONDITIONS EXPECTED DURING THIS PERIOD.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY FOR WINDS UNTIL 8 PM CDT THIS EVENING FOR
     GMZ130-132-135.

&&

$$

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