Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 080555 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1255 AM CDT WED JUL 8 2015

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

.AVIATION...SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE
MOSTLY HIGH CLOUDS ACROSS THE CWA LATE TONIGHT WITH SOME PATCHY
HAZE. CEILINGS WERE NEAR 1600FT AT KHRL TO NEAR 2100FT AT KMFE.
VISIBILITIES WERE NEAR 5SM WITH HAZE AT KPIL TO NEAR 6SM WITH HAZE
AT KMFE. EXPECT MVFR CONDITIONS TO CONTINUE TO DEVELOP THE REST OF
TONIGHT INTO EARLY WEDNESDAY MORNING AS LOW LEVEL MOISTURE ALLOWS
LOW CLOUDS TO DEVELOP. EXPECT VFR CONDITIONS TO PREVAIL AFTER 15Z
WEDNESDAY AS MIXING INCREASES WITH DIURNAL HEATING ALLOWING LOW
CLOUDS TO ERODE AND BURN OFF.
&&

.PREV DISCUSSION... /ISSUED 623 PM CDT TUE JUL 7 2015/
DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...HIGH PRESSURE IN THE MID LAYERS TO KEEP SUFFICIENT
MOISTURE FOR CLOUD FORMATION AT OR BELOW 6000 FEET. DAILY VFR
CUMULUS FIELD TO DISSIPATE THROUGH THE EVENING WITH MOSTLY CLEAR
SKIES OVERNIGHT. MOIST SHALLOW LAYER TO SATURATE BEFORE SUNRISE
WITH PATCHY BRIEF MVFR CIGS AT THE THREE TERMINALS. STRATUS TO MIX
OUT WITH CUMULUS FIELD TO RISE WITH DAYTIME HEATING AND INCREASING
SOUTHEAST WIND PRODUCING SCT-BKN VFR SKIES. MAIN CONCERN IS THE STRONG
SOUTHEAST WINDS TO SLOWLY DIMINISH BY 03Z WITH GUSTS FALLING
BELOW 20 KNOTS. A LOW LEVEL JET OF 25 TO 30 KNOTS AT 2-4K FEET PERSIST
THROUGH THE NIGHT AND SHOULD MIX TO THE SURFACE WEDNESDAY
PROVIDING ANOTHER STRONG AND GUSTY DAY WITH GUSTS IN THEE
25 TO 30 KNOT RANGE.

PREV DISCUSSION... /ISSUED 335 PM CDT TUE JUL 7 2015/

SHORT TERM  /TONIGHT THROUGH WEDNESDAY NIGHT/...500 MB RIDGING OVER THE
WESTERN ATLANTIC WILL BUILD STEADILY WEST TOWARDS TX AND THE GULF OF
MEX WHILE A 500 MB CLOSED LOW DIGS INTO THE DESERT SW STATES. THIS
PATTERN WILL MAINTAIN A GENERALLY DRIER AND MORE STABLE ATMS OVER
DEEP SOUTH TX AS DEEP LAYER MOISTURE WILL TEND TO BE SHUNTED AROUND
THE WESTERN AND NORTHERN SIDES OF THE 500 MB RIDGE. SO EXPECT FAIRLY
STATUS QUO CONDITIONS TO CONTINUE ACROSS THE REGION WITH OVERALL
TEMPS FOR THE REGION REMAINING CLOSE TO A LITTLE BIT ABOVE CLIMO FOR
THE FIRST HALF OF JULY. ENOUGH SHALLOW LOW LEVEL MOISTURE WILL
LINGER OVER THE REGION TO MAINTAIN GENERALLY PARTLY CLOUDY
CONDITIONS FOR MUCH OF THE SHORT TERM. HOWEVER THE CONV POTENTIAL
WILL REMAIN NEAR ZERO. AS THE 500 MB CLOSED LOW PUSHES INTO THE
DESERT SW THE SURFACE PGF WILL REMAIN FAIRLY STRONG THROUGH WED
WHICH WILL KEEP BREEZY CONDITIONS IN PLACE INTO THE AFTERNOON HOURS.

THE SHORT TERM TEMP AND POP GUIDANCE IS IN PRETTY DECENT AGREEMENT
THROUGH WED NIGHT. A FEW DISCREPANCIES SHOW UP CONCERNING THE
OVERNIGHT LOWS WITH THE MAV AND MET COMING IN A BIT COOLER VERSUS
THE ECMWF NUMBERS. WILL LEAN A LITTLE CLOSER TO A MAV/MET BLEND FOR
LOWS TONIGHT AND WED NIGHT. HIGHS WILL BE A GENERAL BLEND

LONG TERM /THURSDAY THROUGH TUESDAY/...THE DRY OF JULY SOLDIERS
ON THROUGH THE MIDDLE OF THE MONTH AS THE HIGHLY ANTICIPATED
SPRAWLING 500 MB RIDGE SETS UP INITIALLY FROM THE SOUTHEAST U.S.
SOUTHWESTWARD TO CHIHUAHUA/COAHUILA STATE (MEXICO) TO CLOSE THE
WEEK AND START THE WEEKEND...THEN EASES WEST TO A POSITION
CENTERED OVER THE SOUTHERN PLAINS TO CLOSE THE WEEKEND BEFORE
PARKING OVER THE TEXAS PANHANDLE NEXT MONDAY AND TUESDAY. THE MORE
WESTERN REFORMATION COMES COURTESY OF DOWNSTREAM TROUGHING ACROSS
THE MID ATLANTIC AND NORTHEAST...WITH THE TROUGH AXIS EVENTUALLY
DIPPING INTO THE SOUTHEAST U.S. THE FARTHER WEST POSITION OF THE
500 MB HIGH IS QUITE CONSISTENT WITH BOTH A MODERATE TO STRONG
SUMMER EL NINO AND THE CLIMATOLOGICAL `CANICULA` PERIOD...WHEN
SEARING HEAT AND LOW RAINFALL MATCH THE RISING OF SIRIUS (DOG
STAR) WITH THE MORNING SUN FROM MID JULY TO MID AUGUST. DOG DAYS
INDEED.

FOR THE SENSIBLE WEATHER:  THE VALLEY WIND MACHINE THAT HAS PEAKED
TODAY WITH GUSTS NEAR 40 MPH AND IS LIKELY TO CONTINUE WEDNESDAY
WILL BEGIN TO SLOWLY RELAX ON THURSDAY AS THE SURFACE RIDGE OOZES
WEST THROUGH THE GULF WHILE LOWER PRESSURES RECEDE INTO THE NORTHERN
PLAINS. STILL ENOUGH RESIDUAL DEEP SOUTHERLY FLOW TO MAINTAIN SOME
HAZE...PART FROM THE SAHARA BUT A GOOD DEAL LIKELY FROM GENERAL
POLLUTION FROM CENTRAL AMERICAN NORTHWARD THROUGH EASTERN MEXICO.
BUT SKIES AND GOOD AIR QUALITY (FROM LOWER PARTICULATES) SHOULD
BECOME A BIT BLUER AS MEAN FLOW THROUGH 15K FEET BECOMES
SOUTHEASTERLY...FROM THE TROPICAL GULF AND WESTERN CARIBBEAN.

FRIDAY THROUGH SUNDAY WILL SEE FURTHER DROPPING OF WINDS TO MODERATE
LEVELS...10 TO 20 MPH BY DAY AND 5 MPH BY NIGHT...AS THE SURFACE
RIDGING SPREADS WEST. AS FOR PRECIPITATION...PREVIOUS FORECAST HAD
SPLOTCHY SHOWERS ACROSS PARTS OF THE VALLEY ON SATURDAY AND WHILE
THE GFS HINTS AT A SUBTLE UPTICK IN 850-700 MB MOISTURE JUST NOT
ENOUGH CONFIDENCE FOR MENTIONABLE RAIN...BUT WILL ACCOUNT FOR MORE
CLOUDINESS INLAND ON SATURDAY.

LATER SUNDAY AND ESPECIALLY MONDAY AND TUESDAY SEE FAIRLY DRAMATIC
DEEP ATMOSPHERIC DRYING...WHICH REDUCES CLOUD COVER TO NEAR NIL AT
MOST TIMES AND SHOULD HELP BOOST TEMPERATURES A FEW NOTCHES AS BOTH
1000-500 THICKNESS PUSHES TO NEAR 582 DM EACH AFTERNOON AND 850MB
TEMPERATURE OVER 22C FROM THE MID VALLEY TO THE RIO GRANDE PLAINS.
THIS WOULD SUGGEST CENTURY MARK LEVELS FINALLY REACH THE MID VALLEY
WITH SLIGHTLY LOWERING HUMIDITY DUE TO DRY AIR MIXING TO KEEP
APPARENT TEMPERATURES REASONABLE.  THE DELAY IN CENTURY-MARK
TEMPERATURES IS PARTLY DUE TO A SLIGHTLY `COOLER` ATMOSPHERE BUT
PROBABLY MORE DUE TO ABUNDANT SUBSOIL MOISTURE AND CONTINUED
EVAPOTRANSPIRATION INCLUDING TO THE RIO GRANDE PLAINS. THIS TYPE OF
PATTERN IS CLASSIC FOR RAPID DRYING AND SUBSOIL EFFECTS ARE LIKELY
TO DRY UP...LITERALLY...BY EARLY NEXT WEEK WHICH ALLOWS INSOLATION
TO GO STRAIGHT INTO HEATING AND AUGURS WELL FOR A STRING OF 100+
DEGREE DAYS RATHER THAN ONE-OFFS.

AT THE BEACH...UPWELLING HAS COOLED THE SURF INTO THE MID TO UPPER
70S AND THIS WILL CONTINUE THROUGH THE WORKWEEK.  THAT UPWELLING
ALSO SHARPLY REDUCES NEARSHORE AND BEACH WINDS...AND HAVE ACCOUNTED
FOR THIS IN THE FORECAST THURSDAY AND FRIDAY. BY SATURDAY...THE
TENDENCY FOR EAST-SOUTHEAST SURFACE WINDS WILL CREATE A BIT MORE
UNIFORMITY ALONG THE COAST AND INTO THE GULF...THOUGH SST RECOVERY
IN THE NEARSHORE WATERS MAY LAG A BIT AND HOLD WINDS DOWN FOR
ANOTHER DAY.

MARINE...NOW THROUGH WEDNESDAY NIGHT...SURFACE OBS NEAR THE LAGUNA
MADRE INDICATE THAT SOME FAIRLY STRONG INLAND WINDS MAY BE EDGING
INTO THE WESTERN PORTIONS OF THE BAY. SO WILL MAINTAIN THE SCA FOR
THE BAY WATERS THROUGH THIS AFTERNOON AND THIS EVENING. BUOY020
REPORTS A SSE WIND IN THE 15 TO 20 KNOT RANGE WITH SWELLS
REACHING AROUND 6 FEET. EXPECT THE PGF TO REMAIN STRONG ENOUGH
TONIGHT TO KEEP THE GULF SWELLS FAIRLY ELEVATED DESPITE THE COOLER
WATER TEMPS. THIS WILL BE STRONG ENOUGH TO MAINTAIN SOME MENTION
OF SCEC WORDING FOR THE OFFSHORE WATERS THROUGH TOMORROW NIGHT.

THURSDAY THROUGH FRIDAY:  AS MENTIONED ABOVE...UPWELLING
OF COOLER WATERS IN THE NEARSHORE WATERS CUTTING DOWN MIXING...TO AS
MUCH AS 25-40% OF BOUNDARY LAYER VALUES TODAY AS INDICATED BY TEXAS
A&M RESEARCH BUOY `J` WHICH IS ABOUT 8 MILES EAST OF SOUTH PADRE.
EXPECT THIS TO CONTINUE THURSDAY INTO FRIDAY AND WILL LOWER VALUES
SEVERAL KNOTS.

WINDS WILL STILL BE A BIT STIFF ACROSS THE LAGUNA MADRE FROM LATE
EACH MORNING THROUGH EARLY EVENING...BUT FAIRLY TOLERABLE FOR EARLY
MORNING FISHING/BOATING TRIPS.

SATURDAY AND SUNDAY:  THE BACKING OF WINDS TO THE EAST/SOUTHEAST
SHOULD HELP REDUCE UPWELLING AND BRING MORE UNIFORM MODERATE WINDS
ACROSS ALL WATERS...WHICH GENERALLY MEANS A NICE SITUATION FOR
BOATING AND FISHING ALIKE AS SEAS DIP WITH THE LOSS OF THE DEEPER
SOUTHEAST FLOW OVER THE FARTHER OFFSHORE WATERS.
&&

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

$$

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