Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 300937
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
437 AM CDT TUE JUN 30 2015

.SHORT TERM /TODAY THROUGH WEDNESDAY/...LATEST WATER VAPOR IMAGERY
SHOWS THAT THE REGION IS BETWEEN TWO 500MB RIDGES...ONE OVER THE
ROCKIES AND THE OTHER OVER THE EASTERN GULF OF MEXICO. TWO FEATURES
PREVAIL OVER DEEP SOUTH TEXAS THIS MORNING. A 250MB TROUGH WITH THE
ASSOCIATED NORTHWEST FLOW IS PROVIDING SOME CIRRUS TO STREAM
OVERHEAD. ALSO...A WEAK 500MB LOW/INVERTED TROUGH OVER NORTHEAST
MEXICO INTO DEEP SOUTH TEXAS IS BRINGING SOME LOW TO MID LEVEL
MOISTURE ACROSS THE WESTERN GULF OF MEXICO INTO THE AREA THIS
MORNING. IR SATELLITE THIS MORNING SHOWS A PLUME OF MOISTURE OVER
THE SOUTHWEST GULF OF MEXICO...ALONG THE MEXICAN COAST LINE...MOVING
NORTHWARD. BROWNSVILLE RADAR CURRENTLY INDICATES SCATTERED SHOWERS
AND THUNDERSTORMS OVER THE LOWER TEXAS GULF WATERS AND SOUTH OF THE
RIO GRANDE RIVER. THIS CONVECTION WILL CONTINUE TO MOVE TO THE
NORTHWEST AND AFFECT MOST OF THE RIO GRANDE VALLEY THROUGH SUNRISE.

THE SURGE OF MOISTURE...THE PERSISTENT WEAKNESS OVERHEAD AND DAYTIME
HEATING WILL SUPPORT A CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS
THE AREA TODAY AND WEDNESDAY. DIFFERENCES CONTINUE THIS MORNING
BETWEEN THE NAM/GFS/ECMWF...THEREFORE WILL LEAN TOWARDS A MODEL
BLEND FOR POPS TODAY THROUGH WEDNESDAY. ALSO...WILL CONTINUE TO
MENTION HEAVY RAINFALL TODAY AND WEDNESDAY DUE TO THE DEEP TROPICAL
AIRMASS IN PLACE.

THE ABUNDANT CLOUD COVER AND INCREASE RAIN CHANCES WILL KEEP HIGH
TEMPERATURES BELOW NORMAL DOWN THROUGH THE PERIOD. HIGH TEMPERATURES
TODAY AND WEDNESDAY WILL RANGE FROM THE 80S ALONG THE BEACHES...THE
LOW 90S ACROSS THE VALLEY AND THE MID 90S ACROSS THE WEST. LOW
TEMPERATURES TONIGHT WILL BE IN THE MID 70S ACROSS THE NORTHERN
RANCHLANDS TO THE UPPER 70S TO AROUND 80 NEAR THE COAST.

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...LONGER RANGE
GUIDANCE MAINTAINS BROAD 500 MB TROFFING AND SOME DEEPER LAYER
MOISTURE IN PLACE OVER CENTRAL AND EASTERN MEXICO WED NIGHT
THROUGH FRI NIGHT. THE GFS AND ECMWF ARE NOW IN BETTER AGREEMENT
KEEPING THIS TROFFING AND ASSOCIATED TROPICAL MOISTURE SHUNTED A
BIT FURTHER SOUTH AND WEST OF THE RGV WHICH WILL TEND TO LIMIT THE
CONV POTENTIAL DURING THE LATTER HALF OF THE WORK WEEK. HOWEVER
DAYTIME HEATING MAY INITIATE SOME SPOTTIER CONV MAINLY DURING THE
AFTERNOON HOURS. SO WILL LEAVE IN SOME 20 TO 30 % POPS DURING THIS
PERIOD. AS THE HOLIDAY WEEKEND APPROACHES BOTH THE GFS AND ECMWF
MODELS INDICATE ANOTHER SURGE OF TROPICAL MOISTURE PUSHING INTO
DEEP SOUTH TX DURING THE PERIOD FROM SAT THROUGH SUN. SO WILL
MAINTAIN SOME HIGHER CHC POPS FOR THE WEEKEND WITH A LITTLE MORE
CONV COVERAGE EXPECTED.

BELIEVE THAT THE GFS MAY HAVE TOO LOW OF A BIAS FOR POPS IN THE
LONGER RANGE PERIOD AND WILL LEAN CLOSER TO THE HIGHER ECMWF POPS
THROUGH DAY 7.

FOR TEMPS EXPECT THE HIGHS TO A LITTLE MORE LIMITED IN THE LONGER
RANGE PERIOD AS THE CONV THREAT WILL TEND TO LIMIT THE DAYTIME
WARMUP SOMEWHAT. SO WILL GO A LITTLE BELOW GUIDANCE AND CLIMO FOR
HIGHS THROUGH MON AND CLOSER TO CLIMO FOR LOWS.

OVERALL CONFIDENCE IN THE LONGER RANGE FORECAST WORDING IS
GENERALLY A LITTLE ABOVE AVERAGE. MODELS CONTINUE TO SHOW SOME
PRETTY SIGNIFICANT DIFFERENCES FROM DAYS 3 THROUGH 7 IN THE
HANDLING OF THE PCPN POTENTIAL WITH THE ECMWF MAINTAINING A WET
BIAS VERSUS THE GFS.

.MARINE /NOW THROUGH WEDNESDAY/...LIGHT TO MODERATE SOUTH TO
SOUTHEAST WINDS PREVAIL ALONG THE LOWER TEXAS COAST THIS MORNING.
BUOY 42020 CURRENTLY REPORTING SOUTHEAST WINDS AT 17 KNOTS WITH SEAS
OF 3.6 FEET. BROAD HIGH PRESSURE OVER THE GULF INTERACTING WITH
LOWER PRESSURE OVER THE SOUTHWEST GULF WILL MAINTAIN LIGHT TO
MODERATE SOUTHEAST FLOW WITH SEAS GENERALLY 2 TO 4 FEET NEAR SHORE
AND 3 TO 5 FEET OFFSHORE FOR TODAY AND TONIGHT. THE FLOW BECOMES MORE
MODERATE ON WEDNESDAY AS THE GRADIENT STRENGTHENS. SHOWERS AND
THUNDERSTORMS ARE ANTICIPATED ACROSS THE LOWER TEXAS COASTAL WATERS
THROUGH THE PERIOD.

WEDNESDAY NIGHT THROUGH SATURDAY...THE PGF MAY INCREASE A BIT
ALONG THE LOWER TX COASTLINE PUSHING THE WINDS AND SEAS UP SOME
LATER THIS WEEK. THIS MAY RESULT IN SOME MARGINAL SCA CONDITIONS
AS THE HOLIDAY WEEKEND APPROACHES. THE ROUGHEST CONDITIONS WILL
LIKELY BE CONFINED TO THE GULF WATERS DURING THE PERIOD FROM THURS
THROUGH SAT.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  88  79  88  78 /  50  40  50  20
BROWNSVILLE          90  78  90  77 /  50  40  50  20
HARLINGEN            91  77  91  76 /  50  30  40  20
MCALLEN              92  77  92  78 /  50  40  50  20
RIO GRANDE CITY      94  76  94  75 /  50  20  40  20
SOUTH PADRE ISLAND   86  80  86  81 /  50  40  50  20

&&

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

$$

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

SHORT TERM...63
LONG TERM...60
GRAPHICAST/UPPER AIR...58



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