Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 231805 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
105 PM CDT SAT AUG 23 2014

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

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL FOR THE REST OF THE
AFTERNOON INTO LATE THIS EVENING AS HIGH PRESSURE ALOFT AND AT THE
SURFACE PROVIDES SUBSIDENCE ACROSS THE RIO GRANDE VALLEY. MODERATE
SOUTHEAST WINDS WITH GUSTS UP TO 25 KNOTS WILL CONTINUE THROUGH
THIS EVENING. AMPLE LOW LEVEL MOISTURE AND WILL SUPPORT SOME PASSING
LOW CLOUDS OVERNIGHT. BRIEF MVFR CEILINGS BETWEEN 2000 TO 2500
FEET POSSIBLE AFTER 09Z BUT WILL NOT MENTION AT THIS TIME DUE TO
LOW FORECAST CONFIDENCE. OTHERWISE...EXPECT VFR CONDITIONS AND
LIGHT TO MODERATE SOUTHEAST WINDS OVERNIGHT THROUGH SUNDAY
MORNING.

&&

.PREV DISCUSSION... /ISSUED 617 AM CDT SAT AUG 23 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...VFR TAFS FOR THE NEXT 24 HOURS...WITH A CAVEAT.
SATELLITE IMAGERY SHOWS TROPICAL MOISTURE...MAINLY AC...MOVING
NORTH FROM THE SOUTHWEST GULF...AND FORECAST SOUNDINGS SUGGEST
THAT PWAT SHOULD BE ON THE RISE TOWARD TWO INCHES. THUS...A MORE
ACTIVE SEA BREEZE WILL BE ON THE TABLE FOR TODAY...THOUGH GREATER
AMOUNTS OF MID TO UPPER CLOUDS...DUE TO INCOMING MOISTURE...MAY
TEMPER HEATING AND ANY SEA BREEZE CONVECTION A BIT. DIDN`T PLACE
ANY OVERT MENTION OF POPS IN THE TAFS JUST YET SINCE TIMING AND
STRENGTH WILL BE SOMEWHAT PROBLEMATIC. MAY SEE BKN LOW CLOUDS
DEVELOP NEAR THE COAST FROM MID MORNING THROUGH AFTN...AND A SEA
BREEZE LINE WILL CONSIST MAINLY OF SHOWERS...BUT CEILINGS SHOULD
REMAIN ABOVE 3 KFT. LIGHT TO MDT SOUTHEAST WINDS EXPECTED.

PREV DISCUSSION... /ISSUED 341 AM CDT SAT AUG 23 2014/

SHORT TERM /TODAY THROUGH SUNDAY/...MID LEVEL RIDGING REMAINS
PARKED OVER THE LOWER MISSISSIPPI VALLEY...SUPPORTING HIGH
PRESSURE OVER THE NORTH GULF...WHICH WILL CONTINUE TO INFLUENCE
LOCAL WX CONDITIONS. SHORT WAVE TROUGHS WILL DIG INTO AND MOVE
AROUND THE LARGER SCALE TROUGH OVER THE PACIFIC
NORTHWEST...PRODUCING PRESSURE FALLS OVER THE CENTRAL HIGH PLAINS
AS THEY ASCEND NORTHEAST INTO THE PLAINS RIDGE. WITH DOMINANT HIGH
PRESSURE STRONGLY INFLUENCING SOUTH TEXAS...PRESSURE DECREASES
UPSTREAM WILL HAVE ONLY A WEAK EFFECT ON WINDS ACROSS THE CWA.
TROPICAL MOISTURE SOURCING FROM THE SOUTHWEST GULF WILL TEND TO
SURGE NORTH PERIODICALLY...TOWARD THE LOWER TEXAS
COAST...MARGINALLY INCREASING LOW END POPS CHANCES.

TODAY...MID TO HIGH LEVEL CLOUDS MAY FILTER OUT SOME OF THE EFFECTS
OF AMPLE SUNSHINE...BUT STILL ANTICIPATE MORE ACTIVITY FROM THE SEA
BREEZE TODAY COMPARED TO YESTERDAY...AS THE FORECAST PWAT SHOOTS
BACK UP TO AROUND TWO INCHES TODAY. HIGH TEMPERATURES...THOUGH NOT
RECORD SETTING...WILL BE ABOVE NORMAL BY A FEW TO SEVERAL DEGREES...
FROM THE MID 90S EAST TO A FEW DEGREES ABOVE THE CENTURY MARK OUT
WEST...AND HIGHER DEW POINTS WILL LEAD TO HEAT INDEX VALUES OF 105
TO 110 TODAY. LIGHT TO MODERATE SOUTHEAST WINDS WILL PREVAIL.

TONIGHT...EXPECT MOSTLY CLEAR SKIES WITH LOW TEMPS IN THE MID TO
UPPER 70S OR NEAR 80...WHILE NOCTURNAL SHOWERS MOVE UP FROM THE
SOUTH AND OVER THE NEAR SHORE WATERS AND POSSIBLY OVER COASTAL AREAS.

SUNDAY...ANOTHER DAY OF WARMER THAN NORMAL TEMPERATURES AND LIGHT TO
MODERATE SOUTHEAST WINDS UNDER PARTLY CLOUDY SKIES AS THE SYNOPTIC
PICTURE REMAINS VERY SIMILAR TO THAT OF TODAY.

MAINTAINED THE TREND OF THE PREVIOUS FORECAST PACKAGE. NO BIG MODEL
DIFFERENCES WERE NOTED AND A 50/50 BLEND OF THE OFFICIAL PLUS NEWER
GUIDANCE WAS USED.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...MID LEVEL RIDGE
LOCATED ACROSS THE SOUTHEAST CONUS WILL HOLD FIRM SUNDAY NIGHT
THROUGH TUESDAY AHEAD OF AN APPROACHING TROUGH THAT WILL MOVE INTO
THE CENTRAL PLAINS WEDNESDAY. MAINLY SUBSIDENCE AND DRY AIR WILL
RULE THE DAY THROUGH TUESDAY NIGHT WITH MAINLY DRY CONDITIONS AND
TEMPERATURES A FEW DEGREES ABOVE NORMAL EACH DAY. BASICALLY...
PERSISTENCE FROM THE PAST FEW FORECAST PACKAGES WITH NO MAJOR
CHANGES.

BOTH MODELS PROG A MID LEVEL INVERTED TROUGH MOVING WESTWARD ACROSS THE
GULF ON THE SOUTH SIDE OF THE WEAKENING HIGH PRESSURE AREA. THIS WILL
INCREASE PWATS BEGINNING WEDNESDAY WITH BETTER LOW/MID LEVEL
MOISTURE EXPECTED THURSDAY BELOW DRIER AIR ABOVE 500MB. BELIEVE
ISOLATED SHOWERS WILL OCCUR WEDNESDAY ALONG THE SEA BREEZE WITH A
LITTLE BETTER COVERAGE THURSDAY AND FRIDAY DUE TO THE AFOREMENTIONED
REASONS. WITH INCREASED LATE MORNING AND AFTERNOON CLOUD COVER AND
SHOTS OF PRECIPITATION...TEMPERATURES SHOULD BE MODERATED BY A
DEGREES OR TWO FOR HIGHS WEDNESDAY THROUGH FRIDAY.

HAVING SAID ALL THAT...CONFIDENCE IN SENSIBLE WEATHER DUE TO MODEL
DIFFERENCES IS LOW IN THE LATTER HALF OF THE WEEK DUE TO THE
WEAKENING HIGH PRESSURE AND THE STRENGTH/SPEED OF CENTRAL PLAINS
TROUGH. THE GFS IS STRONGER/FASTER WITH THE TROUGH AND EVEN SWINGS A
FRONT INTO SOUTH TEXAS FRIDAY. THE ECMWF IS SLOWER AND WEAKER WITH
THE TROUGH AND WASHES THE FRONT OUT WELL NORTH OF THE AREA. WILL
KEEP PERSISTENCE GOING FOR NOW AND USE WPC LONG RANGE GUIDANCE WHICH
IS IN THE ECMWF CAMP FOR NOW UNTIL BETTER AGREEMENT BETWEEN THE
MODELS IS MADE.

MARINE...TODAY THROUGH SUNDAY...MID LEVEL RIDGING OVER THE LOWER
MISSISSIPPI VALLEY WILL SUPPORT HIGH PRESSURE OVER GULF OF
MEXICO...WHICH WILL MEANDER OVER THE NORTH AND NORTHEAST GULF IN
THE SHORT TERM...AND WILL RESULT IN LIGHT TO MODERATE SOUTHEAST
WINDS AND ASSOCIATED LOW TO MODERATE SEAS. CONDITIONS WILL
CONTINUE TO BE MORE UNSETTLED OVER THE SOUTHWEST GULF AND SOME OF
THAT ACTIVITY IN THE FORM OF MOISTER AIR AND ISOLATED TO SCATTERED
SHOWERS AND TSTMS WILL TEND TO MOVE NORTH TOWARD AND INTO THE
LOWER TEXAS COASTAL WATERS. SMALL CRAFT ADVISORY CONDITIONS WILL
BE UNLIKELY THROUGH SUNDAY HOWEVER.

SUNDAY NIGHT THROUGH WEDNESDAY...FOR THE MOST PART HIGH
PRESSURE WILL PREVAIL ACROSS THE COASTAL WATERS THIS PERIOD. LIGHT
TO MODERATE SOUTHEAST WINDS AND LOW TO MODERATE SEAS ARE EXPECTED
THIS PERIOD. A FEW LATE NIGHT STREAMER SHOWERS CANNOT BE RULED OUT
WITH BETTER COVERAGE TUESDAY NIGHT INTO WEDNESDAY.

&&

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

$$

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