Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 182333 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
633 PM CDT FRI APR 18 2014

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

&&

.AVIATION...DRIER AIR HAS FILTERED IN FROM THE NORTHEAST AND HAS
TEMPORARILY ALLOWED FOR MVFR CIGS TO BECOME VFR. SUFFICIENT LOW
LEVEL MOISTURE REMAINS IN PLACE FOR REDEVELOPMENT OF MVFR CIGS
OVERNIGHT. ONSET OF THE LOWER CLOUD COVER IS EXPECTED AT OR AFTER
06Z WITH LOWEST CONDITIONS AN HOUR EITHER SIDE OF SUNRISE SATURDAY.
PATCHY FOG HAS A LOW PROBABILITY TO FORM AT THE TERMINAL AIRPORTS
AND IF IT DOES IT SHOULD ONLY LOWER VSBY TO MVFR BETWEEN 10-13Z.
MVFR CIGS TO MIX OUT SHORTLY AFTER 16Z SATURDAY WITH VFR CONDITIONS
RESUMING. LIGHT NORTHEAST WINDS TO TURN SOUTHEAST BY SATURDAY
REMAINING LESS THAN 15 KNOTS TONIGHT AND GUSTING TO 20 KNOTS
SATURDAY AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 224 PM CDT FRI APR 18 2014/

SHORT TERM /NOW THROUGH SATURDAY NIGHT/...COASTAL TROUGHING OVER THE
WESTERN GULF OF MEXICO IS LEADING TO A FEW AREAS OF LIGHT RAIN
ACROSS THE LOWER VALLEY. SATELLITE DEPICTS MULTILAYERED LOW AND MID
CLOUDS BLANKET THE AREA WITH LITTLE IF ANY SUNSHINE REACHING THE
SURFACE. ALOFT...THE AREA RESIDES UNDER UPPER LEVEL RIDGING WITH A
DEPARTING LOW PRESSURE AREA ACROSS THE SOUTHEAST CONUS AND AN UPPER
LEVEL TROUGH OFF THE SOUTHERN CALIFORNIA COAST. DEEP SUBTROPICAL TAP
IS IN PLACE TO OUR WEST WITH PLENTY OF MID AND UPPER LEVEL MOISTURE
BEGINNING TO STREAM INTO THE FOUR CORNERS AREA AND NORTHERN MEXICO.

COASTAL TROUGHING WILL WEAKEN AND DISSIPATE TONIGHT AS SFC HIGH
PRESSURE SETTLES ALONG THE NORTHERN TEXAS COAST. THIS WILL CAUSE
WINDS TO WEAKEN SIGNIFICANTLY AND DESPITE PARTLY TO MOSTLY CLOUDY
SKIES OVERNIGHT...PATCHY FOG WILL BE POSSIBLE ACROSS FOG PRONE AREAS
ALONG AND EAST OF HWY 281. INHERITED LOW TEMPERATURES LOOK
REASONABLE...READINGS IN THE 60S.

UPPER LEVEL TROUGH MOVES INTO THE DESERT SOUTHWEST SATURDAY AND
SATURDAY NIGHT. SUBTROPICAL STREAM AND ASSOCIATED MOISTURE MOVES
OVERHEAD WITH A DENSE CIRRUS SHIELD OVERSPREADING THE AREA. WITH
SOUTHWESTERLY FLOW ALOFT...WEAK EMBEDDED DISTURBANCES...AND BROAD
DIFFLUENCE ALOFT...ISOLATED THUNDERSTORMS WILL BE POSSIBLE WEST OF
THE CWA OVER THE HIGHER TERRAIN SATURDAY AFTERNOON AND EVENING.
THERE IS A CHANCE...ALBEIT SLIGHT CHANCE...THAT ONE OR TWO MAY MOVE
INTO THE WESTERN CWA. HOWEVER...THE CAP WILL BE STRONG OUT WEST
OWING TO SOUTHWESTERLY WINDS IN THE MID LEVELS. HAVE SLIGHT CHANCES
OF THUNDERSTORMS SATURDAY AFTERNOON AND EVENING FOR MAINLY
ZAPATA...JIM HOGG...AND STARR COUNTIES. NUDGED HIGHS SATURDAY DOWN A
DEGREE HERE AND THERE BASED ON EXPECTED CLOUD COVER. SATURDAY NIGHT
LOWS LOOKED GOOD.

LONG TERM /SUNDAY THROUGH FRIDAY/...A 500 MB TROUGH AXIS WILL
PUSH WEST ACROSS THE SOUTH CENTRAL PLAINS STATES FROM SUNDAY ON
THROUGH MONDAY AND TUESDAY. THIS TROUGH WILL THEN BE FOLLOWED BY
500 MB RIDGING PUSHING OVER THE AREA FROM TUES THROUGH WED WITH A
LARGE 500 MB CLOSED LOW PUSHING ACROSS THE UPPER MIDWEST DURING
THE LATTER HALF OF NEXT WEEK. OVERALL MOISTURE ADVECTION OVER THE
AREA LOOKS PRETTY LIMITED WITH RH VALUES DIMINISHING EVEN MORE
SOAS THE 500 MB RIDGING BUILDS IN OVER THE REGION. THE 500 MB
CLOSED LOW MOVING ACROSS THE UPPER MIDWEST WILL BE LOCATED WELL TO
THE NORTH OF DEEP SOUTH TEXAS TO PROVIDE ANY DECENT MOISTURE
ADVECTION LATER NEXT WEEK. SO WILL MAINTAIN ONLY A MENTION OF SLGT
CHC POPS AS THE 500 MB TROUGH MOVES OVER THE AREA EARLY NEXT WEEK.

SURFACE WAA AND THE 1000-500 MB THICKNESSES WILL BE ON THE
INCREASE THROUGHOUT THE LONGER RANGE PERIOD WHICH WILL ALLOW TEMPS
TO CONTINUE WARMING. THE ECMWF AND GFS MEX MOS TEMPS ARE IN
REASONABLE AGREEMENT THROUGH DAY 7 WITH THE ECMWF SHOWING A
SLIGHTLY WARMER BIAS. WILL LEAN TOWARDS A 50/50 MODEL BLEND
BETWEEN THE ECWMF AND GFS MODELS SETS FOR TEMPS.

RUN TO RUN CONSISTENCY WITH THE GFS MEX MOS GUIDANCE IS PRETTY
STABLE THROUGH DAY 7. MODEL TO MODEL CONSISTENCY BETWEEN THE GFS
AND ECMWF IS IN PRETTY GOOD AGREEMENT. SO OVERALL CONFIDENCE IN
THE LONGER RANGE FORECAST WORDING IS ABOVE AVERAGE.

MARINE...NOW THROUGH SATURDAY NIGHT...BUOY 42020 REPORTED NORTHEAST
WINDS AROUND 13 KNOTS GUSTING TO AROUND 16 KNOTS WITH SEAS
SLIGHTLY UNDER 6 FEET WITH A PERIOD OF 8 SECONDS AT 13 CDT/18 UTC.
SMALL CRAFT WILL LIKELY NEED TO EXERCISE CAUTION INTO TONIGHT FOR
THE GULF OF MEXICO WATERS EAST OF PADRE ISLAND DUE TO SEAS.
IMPROVED MARINE CONDITIONS ARE EXPECTED LATE TONIGHT INTO SATURDAY
NIGHT AS SURFACE HIGH PRESSURE BECOMES CENTERED ROUGHLY OVER THE
UPPER TEXAS COAST.

SUNDAY THROUGH WEDNESDAY...A MODERATE PGF WILL PREVAIL THROUGHOUT
THE LONGER RANGE CWF PERIOD AS SURFACE RIDGING PREVAILS OVER THE
GULF OF MEX. THIS WILL LIKELY KEEP THE BAY AND GULF WINDS AND SEAS
DOWN BELOW SCA LEVELS. HOWEVER ON AND AFTER WEDNESDAY...A SURFACE
LOW DEVELOPING OVER THE CENTRAL PLAINS STATES WILL LIKELY
STRENGTHEN THE PGF ALONG THE LOWER TX COASTLINE POSSIBLY PUSHING
CONDITIONS UP CLOSE TO SCA LEVELS.

&&

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

$$

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