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000
FXUS64 KBRO 121740
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1240 PM CDT WED JUN 12 2013

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

&&

.AVIATION...CONVECTION TO OUR SOUTH DID NOT MAKE MUCH HEADWAY INTO
THE RGV THIS MORNING AND HAS GREATLY DIMINISHED. THE 12Z BRO
SOUNDING SHOWED A MOIST AND UNSTABLE AIRMASS OVER THE REGION THIS
MORNING. AVIATION FORECAST THIS AFTERNOON WILL DEPEND ON THE
DEVELOPMENT OF SEABREEZE ACTIVITY ACROSS THE REGION. AM NOT TOO
CONFIDENT AT THIS POINT THAT THERE WILL BE MUCH CONVECTIVE
ACTIVITY THIS AFTERNOON. VERY FEW CU HAVE DEVELOPED SO FAR TODAY
AND FLOW AT 700 MB IS FROM THE SOUTH. EXPECT GENERALLY VFR
CONDITIONS TO PREVAIL THROUGH MUCH OF THE PERIOD WITH PERIODS OF
MVFR TOWARDS DAYBREAK.

&&

.PREV DISCUSSION... /ISSUED 653 AM CDT WED JUN 12 2013/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...THE CONV COMPLEX TO OUR SOUTH HAS NOT MADE MUCH
PROGRESS TO THE NORTH OVER THE LOWER RGV AREA. THE 00Z BRO SOUNDING
SHOWS A PRETTY MOIST AND UNSTABLE AIRMASS IN PLACE OVER THE
REGION AND FORECAST SOUNDINGS DO NOT SHOW MUCH IN THE WAY OF DRIER
AIR FILTER INTO THE REGION. SO EXPECT CAPES AND PWATS TO REMAIN
HIGH THROUGHOUT THE DAY WHICH WILL LIKELY MAINTAIN SOME TYPE OF
CLD COVER OVER THE REGION. THE COMBINATION OF THE 500 MB LOW TO
OUR WEST...THE MOIST AND UNSTABLE AIRMASS AND THE DAYTIME HEATING
KICKING IN LATER WILL MAINTAIN THE THREAT OF SOME CONV POTENTIAL
THROUGHOUT THE DAY. HOWEVER AM NOT TERRIBLY CONFIDENT OF
WIDESPREAD COVERAGE TODAY AND WILL MAINTAIN ONLY SOME TEMPO
REMARKS FOR CONV MAINLY THIS AFTERNOON DURING THE PEAK HEATING.
EXPECT VFR CONDITIONS TO PREVAIL GENERALLY WITH SOME BRIEF
REDUCTIONS TO MVFR/IFR LEVELS.

PREV DISCUSSION... /ISSUED 435 AM CDT WED JUN 12 2013/

SHORT TERM /TODAY THROUGH THURSDAY/...THE 500 MB LOW WILL MAINTAIN
SOME INFLUENCE OVER DEEP SOUTH TEXAS THROUGHOUT THE SHORT TERM
PERIOD EVEN AS THE LOW SHIFTS GRADUALLY AWAY FROM THE REGION. ENOUGH
PVA WILL MEANDER ACROSS THE AREA TODAY AND THURSDAY TO MAINTAIN
DECENT DIVERGENCE ALOFT TO HELP FIRE OFF SOME CONV THROUGHOUT TODAY
AND TOMORROW. THE 00Z BRO SOUNDING SHOWS A FAIRLY MOIST AND UNSTABLE
ATMS OVER THE REGION WITH A PWAT OF 2.14 INCHES AND A CAPE OF
2589J/KG. BOTH THE NAM AND GFS FORECAST SOUNDINGS MAINTAIN THESE
ELEVATED PWAT AND CAPE VALUES THROUGH THURS AFTERNOON WITH DRIER AIR
FINALLY STARTING TO MOVE INTO THE REGION AFTER THURS. BELIEVE THAT
THE LINGERING INFLUENCE OF THE 500 MB LOW TO OUR WEST AND NORTH IN
COMBINATION WITH THE DAYTIME HEATING DESTABILIZING THE ATMS WILL BE
ENOUGH TO JUSTIFY SOME SLGT CHC/CHC POPS ON THROUGH THURS.

THE MAV AND MET GUIDANCE ARE IN PRETTY GOOD AGREEMENT IN THE TIMING
AND THE GENERAL MOVEMENT OF THE 500 MB LOW. THIS TRANSLATES TO
REASONABLE AGREEMENT WITH THE MODEL SETS CONCERNING TEMPS. THE NAM
IS A LITTLE WETTER VERSUS THE GFS FOR POPS THROUGH TOMORROW. THE
ECMWF LEANS CLOSER TO THE NAM FOR POPS. SO WILL GO WITH A BLEND OF
THE MAV/MET GUIDANCE FOR TEMPS WITH A BLEND OF THE MET AND ECMWF
NUMBERS FOR POPS.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...THE LONG TERM STARTS
WITH A 500 MB RIDGE ACROSS THE SOUTHERN PLAINS EXTENDING INTO THE
GULF OF MEXICO AND A 500 MB LOW NEAR THE TEXAS BIG BEND. WILL
MAINTAIN ISOLATED POPS ACROSS THE NORTHWEST FRIDAY INTO SATURDAY
DUE TO THE UPPER LEVEL FEATURE NEAR THE AREA. THE MID/UPPER LEVEL
RIDGE WILL MOVE EAST AND SOUTH THROUGH SATURDAY WHICH WILL
DIMINISH DEEP LAYER MOISTURE ACROSS AREA. ABOVE AVERAGE
TEMPERATURES AND BELOW NORMAL POPS CAN BE EXPECTED THROUGH THE
PERIOD AS RIDGING ALOFT CONTINUES ACROSS THE REGION. BOTH THE
ECMWF/GFS ARE IN PRETTY GOOD AGREEMENT IN THE OVERALL MID/UPPER
LEVEL PATTERN. THE LATEST ECMWF/GFS INDICATED THAT A TROPICAL WAVE
WILL MOVE ACROSS THE YUCATAN PENINSULA ON TUESDAY AND THE
SOUTHWESTERN GULF OF MEXICO ON WEDNESDAY. WILL MAINTAIN 10 POPS
OVER THE AREA BY MID WEEK AS THE 500 MB RIDGE SHOULD KEEP MOST OF
THE MOISTURE SOUTH OF THE RIO GRANDE VALLEY AT THIS TIME.

MARINE...TODAY THROUGH THURSDAY...BUOY020 REPORTS A SE WIND AROUND
13 KTS WITH SWELLS AROUND 3 FEET. EXPECT SURFACE RIDGING OVER THE
GULF COAST AND THE GULF OF MEXICO TO MAINTAIN PRETTY STEADY STATE
WIND AND MARINE CONDITIONS OVER THE BAY AND GULF WATERS THROUGH
THURS. NO SCA CONDITIONS EXPECTED AT THIS TIME.

THURSDAY NIGHT THROUGH SUNDAY...HIGH PRESSURE OVER THE GULF WILL
INTERACT WITH LOW PRESSURE OVER THE SOUTHERN PLAINS. THIS WILL
RESULT IN MODERATE ONSHORE FLOW AND LOW TO MODERATE SEAS.

&&

.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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