000
FXUS64 KBRO 131737 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1237 PM CDT THU JUN 13 2013

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

.AVIATION...SATELLITE AND RADAR IMAGES AS WELL AS SURFACE
OBSERVATIONS INDICATE A MIX OF MID TO HIGH LEVEL CLOUDS ACROSS THE
CWA WITH SHOWERS DEVELOPING ACROSS THE WESTERN PORTIONS EARLY THIS
AFTERNOON. CEILINGS WERE NEAR 7500FT AT KHBV TO NEAR 10000FT KT65.
EXPECT VFR CONDITIONS TO PREVAIL THE REST OF THE AFTERNOON WITH
SHOWERS IN THE VICINITY OF LOCAL AERODROMES AS A 500MB LOW ACROSS
NORTHERN MEXICO CONTINUES TO DRAW MOISTURE FROM THE WESTERN GULF
OF MEXICO INTO NORTHEAST MEXICO AND THE RIO GRANDE VALLEY. MVFR
CEILINGS WILL DEVELOP LATE TONIGHT AS MIXING DECREASES WITH THE
LOSS OF DIURNAL HEATING.
&&

.PREV DISCUSSION... /ISSUED 708 AM CDT THU JUN 13 2013/
DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...THE MARINE CONVECTION HAS PUSHED FURTHER WEST AND IS
NOW SITUATED OVER THE MID AND UPPER RGV MOVING TO THE NORTHWEST AT
AROUND 15 MPH. EXPECT SOME ISOLD TO SCT CONV TO REMAIN A PERIODIC
THREAT TO THE LOWER RGV AIRPORTS THROUGHOUT TODAY DUE TO THE
INFLUENCE OF THE 500 MB LOW TO OUR WEST AND THE MOIST TROPICAL
ATMS IN PLACE. MVFR/VFR CONDITIONS WILL PREVAIL FOR THE MOST PART.
WILL ALSO INCLUDE A MENTION OF SOME PROB30 REMARKS LATE IN THE TAF
PERIOD AS SOME LINGERING MARINE CONV MAY MOVE OVER HRL AND BRO
TOMORROW MORNING.

PREV DISCUSSION... /ISSUED 415 AM CDT THU JUN 13 2013/

SHORT TERM /TODAY THROUGH FRIDAY/...THE BROAD 500 MB LOW OVER THE
TX/MEX BORDER REGION CONTINUES TO DRIFT EVER SO SLOWLY TO OUR WEST
AND NORTH. THIS SLOW MOVEMENT IS MAINTAINING A GENERAL WEAKNESS IN
THE RIDGING OVER DEEP SOUTH TX THIS MORNING. AN ELONGATED LOBE OF
VORTICITY RUNS FROM NEAR THE FAR WESTERN TIP OF TEX SOUTHEAST INTO
THE FAR WESTERN GULF OF MEX. THIS LOBE OF VORTICITY WILL INTERACT
WITH PERSISTENT DEEP LAYER TROPICAL MOISTURE OVER DEEP SOUTH TX (THE
00Z BRO SOUNDING HAD A PWAT OF >2 INCHES WITH A CAPE OF 3883 J/KG)
TO MAINTAIN THE POTENTIAL FOR ISOLD TO SCT CONV FOR TODAY. THE NAM
SOLUTION FOR THIS FEATURE BRINGS THE VORTICITY SOUTH CLOSER TO THE
RGV WITH THE GFS KEEPING THIS VORTICITY POSITIONED FURTHER NORTH OF
THE BRO CWA. BECAUSE OF THE BETTER UPPER LEVEL SUPPORT INDICATED IN
THE MODEL THE NAM IS MUCH WETTER VERSUS THE GFS AND ECMWF GUIDANCE.

AT THIS TIME AM HESITANT TO GO FOR THE WETTER NAM SOLUTION AS THE
MODEL WENT DOWN THIS ROAD YESTERDAY WITH FAIRLY HIGH POPS AND DID
NOT VERIFY WELL AT ALL WITH THE GFS AND ECMWF REFLECTING THE MORE
SPARSE CONV COVERAGE BETTER YESTERDAY. SO WILL GO CLOSER TO THE
DRIER GFS AND ECMWF SOLUTION FOR THE SHORT TERM.

DUE TO THE SLOW NORTHWARD MOVEMENT OF THIS MID LEVEL LOW AND THE
DELAYED ADVECTION OF DRIER AND MORE STABLE AIR INTO THE REGION
TOMORROW WILL ONLY GRADUALLY REDUCE POPS FOR FRIDAY KEEPING 20 %
VALUES IN PLACE.

WITH THE MAV AND ECMWF GUIDANCE SHOWING A DRIER BIAS VERSUS THE NAM
NUMBERS THE MAV/ECMWF HIGHS ARE A BIT HIGHER VERSUS THE NAM. THE
FORECAST TEMPS THROUGH TOMORROW WILL BE CLOSER TO THE WARMER
MAV/ECMWF BLEND DUE TO THE CONTINUED DOUBT ASSOCIATED WITH THE NAM
SOLUTION.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...NO CHANGE IN THE
OVERALL TERM FORECAST REASONING. MID TO UPPER LEVEL RIDGING TO THE
EAST FRIDAY EVENING WILL BUILD OVERHEAD OVER THE WEEKEND INTO NEXT
WEEK. THIS WILL PROVIDE MODERATE SOUTHEAST WINDS AND DRY CONDITIONS
ACROSS THE AREA. WILL MAINTAIN THE INHERITED LOW POPS AS SEABREEZE
CONVECTION LOOKS TO BE VERY LIMITED THROUGH THE PERIOD. TYPICAL JUNE
WEATHER PATTERN EXPECTED FOR DEEP SOUTH TEXAS AND THE RIO GRANDE
VALLEY THROUGH NEXT WEDNESDAY WITH NORMAL TO SLIGHTLY ABOVE NORMAL
TEMPERATURES. AFTERNOON HIGHS RANGING FROM THE LOW 90S NEAR THE
COAST TO AROUND 100 FAR WEST. OVERNIGHT LOW TEMPERATURES WILL BE IN
THE 70S.

MARINE...TODAY THROUGH FRIDAY...THE PERSISTENT SURFACE RIDGING OVER
THE GULF OF MEX WILL MAINTAIN FAIRLY STEADY SE WINDS AND MODERATE
SEAS ACROSS THE LOWER TX BAY AND GULF WATERS THROUGHOUT FRIDAY. THE
PGF MAY STRENGTHEN JUST ENOUGH ALONG THE BAY WATERS TO REACH SCEC
CRITERIA HERE DURING THE AFTERNOON. HOWEVER WILL NOT MENTION THIS AT
THIS TIME. NO SCA CONDITIONS EXPECTED THROUGH FRIDAY.

FRIDAY NIGHT THROUGH MONDAY...FAVORABLE MARINE CONDITIONS EXPECTED
THROUGH THE FORECAST PERIOD. GENERALLY MODERATE ONSHORE FLOW AND
LOW TO MODERATE SEAS ANTICIPATED THROUGH EARLY NEXT WEEK. SCEC
POSSIBLE SATURDAY AND SUNDAY NIGHT AS SOUTHEAST WINDS BRIEFLY
INCREASE ACROSS THE LOWER TEXAS COASTAL WINDS.
&&

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

$$

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

61/53/VEGA