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000
FXUS64 KBRO 120725 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
225 AM CDT WED JUN 12 2013

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

&&

.AVIATION...IR SATL IMAGERY SHOWS SCT TO BKN HIGH LEVEL CLD COVER
MOVING OVER DEEP SOUTH TX. SCT TO NUMEROUS AREAS OF CONV ARE
DEVELOPING TO THE SOUTHEAST OF BRO OVER THE GULF WATERS AND ARE
MOVING UP TO THE N-NW. THE 00Z BRO SOUNDING SHOWS A PRETTY MOIST
AND UNSTABLE AIRMASS IN PLACE OVER THE REGION. EXPECT THE CONV TO
EVENTUALLY SPREAD INLAND LATER TODAY POSSIBLY PRODUCING SOME
REDUCTIONS TO VSBYS AND CEILINGS. AS THE MID LEVEL CLOSED LOW
SHIFTS FURTHER WEST AND NORTH AWAY FROM DEEP SOUTH TEXAS UPPER
LEVEL DIVERGENCE WILL GRADUALLY WEAKEN OVER THE REGION WHICH MAY
LIMIT THE CONV COVERAGE A BIT. GFS AND NAM GUIDANCE MAINTAIN GENERAL
VFR CONDITIONS THROUGHOUT THE NEXT 24 HOURS. WILL KEEP SOME PROB30
GROUPS FOR MVFR CONDITIONS FOR THE AFTERNOON HOURS DURING PEAK
HEATING.

&&

.PREV DISCUSSION... /ISSUED 646 PM CDT TUE JUN 11 2013/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...WITH THE LOSS OF THE HEATING OF THE DAY...MORE TRANQUIL
WEATHER WILL OCCUR OVERNIGHT...HOWEVER HIGH CIRRUS FROM NEIGHBORING
MEXICO WILL WAFT OVERHEAD FROM THE SOUTHWEST. TOMORROW...A 500 MB
LOW PRESSURE SYSTEM WILL GENERATE ADDITIONAL HEAVY SHOWERS...WITH
REDUCTIONS IN VISIBILITY LIKELY IN THEM. LIGHT WINDS TONIGHT WILL
BECOME MODERATE TOMORROW.

PREV DISCUSSION... /ISSUED 317 PM CDT TUE JUN 11 2013/

SHORT TERM.../NOW THROUGH WEDNESDAY NIGHT/...THE UPPER LEVEL LOW
THAT HAS LINGERED OVER THE REGION THE PAST FEW DAYS WILL CONTINUE
TO SLOWLY LIFT TOWARDS THE NORTH NORTHWEST TONIGHT AND INTO
WEDNESDAY WHILE RIDGING BUILDS OVER THE SOUTHERN PLAINS. AS THE
LOW SHIFTS AWAY FROM THE CWA ITS IMPACTS ON THE REGION WILL
LESSEN.

EARLIER CONVECTION THAT HAD BEEN STREAMING IN FROM NORTHERN
MEXICO ACROSS THE LOWER TEXAS COASTAL WATERS AND CAMERON COUNTY HAS
SLOWED AND REMAINS PRIMARILY SOUTH OF THE RIVER. MEANWHILE A FEW
STORMS POPPED UP OVER ZAPATA COUNTY LATE THIS MORNING AND ARE
ONGOING. IN BETWEEN...CONVECTION HAS BEEN SCARCE.  THE BIG QUESTION
FOR THIS FORECAST PACKAGE IS WHAT TO DO WITH THE POPS. THE LATEST
MODEL RUNS SHOWS LOW TO MID LEVEL RIDGING CENTERED OVER LA/MS. DRIER
AIR ASSOCIATED WITH THIS RIDGING BETWEEN 850 MB AND 700 MB APPEARS
TO BE BEING PULLED OVER THE WESTERN GULF WATERS AND ALONG THE LOWER
TEXAS COAST. THIS INTRUSION OF DRIER AIR COULD BE THE REASON WHY
LITTLE CONVECTION HAS FIRED UP ALONG THE SEA BREEZE SO FAR TODAY.
HAVE LOWERED POPS THIS AFTERNOON BUT HAVE KEPT A SLIGHT CHANCE IN
THROUGH THIS EVENING. WHILE THERE WILL BE LESS DIFFLUENCE ALOFT
WEDNESDAY THE ATMOSPHERE WILL REMAIN SOMEWHAT UNSTABLE AND
CONVERGENCE ALONG THE SEABREEZE MAY BE ABLE TO FIRE UP SOME
CONVECTION...SO HAVE MAINTAINED POPS FOR WEDNESDAY.

LONG TERM...THURSDAY THROUGH TUESDAY...THE LONGER RANGE FORECAST
PERIOD WILL BE DOMINATED BY 500 MB RIDGING BUILDING OVER MUCH OF
THE SOUTHERN STATES AND THE GULF OF MEXICO AS THE INVERTED 500 MB
TROUGH THAT HAS PERSISTED OVER THE REGION PUSHES FURTHER WEST.
THIS WILL ALLOW THE DEEP LAYER MOISTURE LEVELS TO DIMINISH OVER
THE REGION WITH 1000-500 MB THICKNESS VALUES INCREASING. THIS WILL
ALLOW FOR A RETURN OF ABOVE AVERAGE TEMPS AND BELOW NORMAL POPS
THROUGH DAY 7.

ECMWF/GFS AND CMC GUIDANCE ARE IN PRETTY GOOD AGREEMENT IN THE
STRENGTH AND POSITIONING OF THE MID LEVEL RIDGING PATTERN AND THE
OVERALL DECREASE IN THE MOISTURE VALUES OVER THE REGION. RUN TO
RUN COMPARISONS OF THE GFS MEX NUMBERS SHOWS PRETTY GOOD AGREEMENT
IN THE LONGER TERM. WILL GO WITH A BLEND OF THE ECX/MEX FOR TEMPS
AND WILL MAINTAIN SILENT 5 TO 10 POPS.

ECMWF/GFS BOTH HINT AT A TROPICAL WAVE MOVING CLOSE TO THE YUCATAN
PENINSULA AROUND 12Z ON THE 18TH. BOTH MODELS KEEP THIS FEATURE
MOVING WEST INTO THE SOUTHWESTERN GULF OF MEX. WITH THE MID LEVEL
RIDGING REMAINING STRONG OVER TX AM A LITTLE SCEPTICAL THAT MUCH
OF THE DEEP LAYER TROPICAL MOISTURE WILL ADVECT OVER DEEP SOUTH
TX BOOSTING UP POPS A BIT. STAY TUNED TO THE LATEST TROPICAL
WEATHER OUTLOOKS FROM NHC CONCERNING THIS POTENTIAL FEATURE.

MARINE...NOW THROUGH WEDNESDAY NIGHT...MODERATE SOUTHEAST WINDS AND
LOW TO MODERATE SEAS WILL PREVAIL THROUGH WEDNESDAY NIGHT WITH
GENERALLY FAVORABLE MARINE CONDITIONS. ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY WILL CONTINUE THROUGH THE PERIOD. STORMS WILL
BE CAPABLE OF LOCALLY GUSTY WINDS AND CLOUD TO SURFACE LIGHTNING.

THURSDAY THROUGH SUNDAY...SURFACE RIDGING WILL REMAIN ENTRENCHED
OVER THE GULF OF MEX INTO THE LONGER RANGE PERIOD KEEPING A STEADY
SE FLOW. THIS WILL KEEP MARINE CONDITIONS BELOW SCA LEVELS THROUGH
NEXT WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  89  80  94  78 /  20  10  10   0
BROWNSVILLE          90  79  95  77 /  20  10  10   0
HARLINGEN            92  78  95  77 /  20  10  10   0
MCALLEN              95  78  98  77 /  20   0   0   0
RIO GRANDE CITY      97  78 100  76 /  10   0   0   0
SOUTH PADRE ISLAND   85  80  88  79 /  20  20  10   0

&&

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

$$

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

SHORT TERM...60
LONG TERM...63