Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 101726 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1226 PM CDT THU APR 10 2014

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

.AVIATION...SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATED
MOSTLY CLEAR SKIES ACROSS THE CWA EARLY THIS AFTERNOON. EXPECT VFR
CONDITIONS TO PREVAIL ACROSS THE RIO GRANDE VALLEY THE REST OF THE
AFTERNOON INTO THIS EVENING. LOW LEVEL MOISTURE WILL INCREASE
ACROSS THE AREA TONIGHT AS NOCTURNAL LOW LEVEL JET DEVELOPS.
EXPECT MVFR CONDITIONS TO DEVELOP ACROSS THE EASTERN PORTIONS OF
THE RIO GRANDE VALLEY LATE TONIGHT AS A RESULT.
&&

.PREV DISCUSSION... /ISSUED 630 AM CDT THU APR 10 2014/
DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...STRONG WINDS PERSIST IN THE LOWEST LEVELS OF THE ATMOSPHERE JUST OFF
THE SURFACE AND HAVE ADDED A NON CONVECTIVE LOW LEVEL WIND SHEAR
FORECAST TO THE TAFS. THOSE WINDS WILL BEGIN TO MIX DOWN AS SURFACE
WINDS AND GUSTS THROUGH THE NEXT 2 TO 3 HOURS. SOUTH TO
SOUTHEASTERLY WINDS GUSTING 28 TO 34 KNOTS THROUGH THE MID TO LATE
MORNING AND AFTERNOON. A SLOW DECREASE IN THE TOP END OF THE GUSTS
IS LIKELY THROUGH THE AFTERNOON AHEAD OF A MORE MARKED DECREASE
AFTER SUNSET. WINDS WILL STILL BE PERSISTENT THROUGH THE NIGHT
GUSTING AT ABOUT 12 TO 17 KNOTS. NEAR SURFACE LAYERS REMAIN DRY AND
VFR IS FORECAST THROUGH THE TAF PERIOD. A SMALL WINDOW FOR MVFR CIG
WILL OPEN BY SUNRISE FRIDAY MORNING.

PREV DISCUSSION... /ISSUED 407 AM CDT THU APR 10 2014/
SHORT TERM /NOW THROUGH FRIDAY/...MODEST MID LEVEL WAVE EVIDENT
ON WATER VAPOR IS APPROACHING THE REGION THIS MORNING WITH ITS
AXIS JUST EAST OF THE TEXAS BIG BEND. 850/925 MB PRESSURE GRADIENT
IS RESPONDING TO THIS TROUGH AND THE ASSOCIATED LEE TROUGHING FROM
WEST SOUTHWESTERLY WINDS OVER THE SIERRA MADRE MOUNTAINS AHEAD OF
THIS TROUGH. BRO VWP SHOWS WINDS OF 35 TO 40 KNOTS IN THE 1000 TO
4000 FT LAYER.

TODAY...THE TIMING OF THE PASSAGE OF THE UPPER TROUGH BY DAYBREAK OR
A LITTLE AFTER SHOULD MARK THE PEAK OF THE LOW LEVEL GRADIENT. WITH
THAT NOT QUITE FORECASTING A WIND ADVISORY DAY WITH THIS FORECAST
PACKAGE WITH WIND SPEEDS AT 25 TO 30 MPH GUSTING 35 TO 40 MPH...OR
IN THAT GENERAL VEIN...ACROSS ALMOST THE ENTIRE CWA. NAM/HIGH RES
WRF/NMM AND SREF SEEM TO AGREE WITH THAT GENERAL PROGRESSION OF
EVENTS AS WELL. NEVERTHELESS IT WILL BE A BREEZY WINDY DAY WITH
WINDS PICKING UP BY 9 TO 10 AM AND PERSISTING MUCH OF THE DAY.
MODELS DO NOTORIOUSLY UNDER DEVELOP THESE QUASI-CYCLONE/LEE TROUGH
INDUCED LOW LEVEL JETS SO THE MORNING BALLOON AT 6 AM MAY PROMPT AN
ADVISORY IF WINDS ARE STRONGER THAN ANTICIPATED.  OTHERWISE A WARM
AND DRY DAY WITH HIGHS IN THE MID 90S TO LOW 90S AND RELATIVE
HUMIDITY VALUES AT GENERALLY COMFORTABLE LEVELS AS THE REGIONAL
AIRMASS STILL HAS NOT RELOADED FROM THE DRY INTRUSIONS OF EARLIER
THIS WEEK.

TONIGHT...WE WILL KEEP SOME DEGREE OF BREEZINESS OVERNIGHT WITH
MOISTURE UP ANOTHER TICK FROM THURSDAY MORNING. LOWS IN THE MID 60S
WITH WIND SPEEDS OF 10 TO 15 MPH PUSHING 20 MPH IN THE EVENING ARE
FORECAST.

FRIDAY...THE LOW LEVEL PRESSURE GRADIENT WILL BE A LITTLE MORE
RELAXED...BUT STILL IMPACTED BY WESTERLY WINDS ALOFT AND SURFACE LEE
TROUGHING SO FORECASTING ANOTHER GENERALLY BREEZY DAY WITH WIND
SPEEDS 20 TO 25 MPH GUSTING 30 TO 35 MPH...ESPECIALLY EAST OF
HIGHWAY 281. HIGHS IN THE LOW TO MID 80S FOR MOST OF THE AREA
APPROACHING 90 TO 92 IN ZAPATA COUNTY.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...A SERIES OF 500 MB
TROUGHS AND A CLOSED LOW WILL DIG INTO THE CENTRAL PLAINS STATES.
THESE TROUGHS WILL EVENTUALLY CARVE OUT A BROAD AND DEEP 500 MB
LONG WAVE TROUGH AXIS DOMINATING MUCH OF THE LOWER 48 STATES EARLY
NEXT WEEK. THIS WILL PULL A PRETTY STRONG SPRING COLD FRONT DOWN
THROUGH DEEP SOUTH TX ON MONDAY WITH COOLER AND DRIER SURFACE HIGH
PRESSURE PREVAILING OVER THE REGION FOR THE FIRST HALF OF NEXT
WEEK. ANY COOLDOWN FROM THIS FRONT WILL BE PRETTY SHORT LIVED AS
500 MB RIDGING BUILDS BACK OVER THE AREA TUES AND WED AND THE
SURFACE HIGH SHIFTS STEADILY EAST ALLOWING FOR A RETURN OF WAA.
MOISTURE ADVECTION WITH THIS NEXT FROPA APPEARS PRETTY LIMITED
BOTH IN THE ECMWF AND GFS MODELS. SO WILL MAINTAIN ONLY 20 TO 30 %
POPS FOR MON AND MON NIGHT.

WILL STICK PRETTY CLOSE TO A MODEL CONSENSUS FOR TEMPS AND POPS AS
BOTH THE ECMWF AND GFS ARE PRETTY MUCH ON THE SAME PAGE IN THE
STRENGTH AND TIMING OF THE NEXT FRONT. RUN TO RUN CONSISTENCY WITH
THE GFS MEX MOS TEMPS AND POPS HAS REMAINED PRETTY STABLE OVER THE
LAST SEVERAL DAYS. OVERALL CONFIDENCE WITH THE LONGER RANGE
FORECAST WORDING IS ABOVE AVERAGE AT THIS TIME.

MARINE...NOW THROUGH FRIDAY...
A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THE LAGUNA MADRE DURING
THE DAY TODAY DUE TO STRONG SOUTH WINDS. WINDS ON THE GULF OF MEXICO
WILL BE A LITTLE LIGHTER BUT STILL AT EXERCISE CAUTION LEVELS ON THE
OFFSHORE WATERS. BREEZY CONDITIONS ARE EXPECTED TONIGHT...LIKELY AT
EXERCISE CAUTION LEVELS TONIGHT. WINDS ARE FORECAST TO BE A LITTLE
LIGHTER ON FRIDAY BUT MAY STILL REACH ADVISORY CRITERIA ON THE
LAGUNA MADRE.

FRIDAY NIGHT THROUGH MONDAY...AS SURFACE TROFFING BUILDS OVER
THE CENTRAL U.S. DUE TO THE DIGGING 500 MB FEATURES...THE PGF WILL
INCREASE ENOUGH TO RESULT IN A MODERATE TO STRONG S-SE SURFACE
LATE IN THE MARINE FORECAST PERIOD. SOME SCA CONDITIONS WILL BE
POSSIBLE AS THE WINDS AND SEAS STRENGTHEN.
&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY FOR WINDS UNTIL 6 PM CDT THIS EVENING FOR
     GMZ130-132-135.
&&

$$

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