Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 290937
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
437 AM CDT MON JUN 29 2015

.SHORT TERM /NOW THROUGH TUESDAY/...LATEST WATER VAPOR IMAGERY
SHOWS 500MB RIDGING OVER THE ROCKIES AND OVER THE EASTERN GULF OF
MEXICO. DEEP SOUTH TEXAS AND THE RIO GRANDE VALLEY WILL CONTINUE
TO REMAIN BETWEEN THESE TWO FEATURES WITH BROAD WEAKNESS OVERHEAD
THROUGH THE FORECAST PERIOD. SOME HIGH LEVEL CLOUDINESS CONTINUES
TO STREAM OVERHEAD THIS MORNING DUE TO THE NORTHWEST FLOW ALOFT.
SURFACE OBSERVATIONS INDICATE THAT SOME PATCHY FOG HAS DEVELOPED
ACROSS PORTIONS OF THE NORTHERN RANCHLANDS AND THE RIO GRANDE
VALLEY OVERNIGHT. THE PATCHY FOG WILL LINGER ACROSS THE AREA NOW
THROUGH JUST AFTER SUNRISE BEFORE MIXING OUT BY MID MORNING.

LESS CONVECTION IS EXPECTED TODAY AS THE AREA REMAINS FAIRLY CAPPED
DUE TO THE SOUTHERLY FLOW AND DRYING BETWEEN 850-700MB. WILL
CONTINUE TO MENTION A SLIGHT CHANCE OF SEABREEZE CONVECTION
TODAY...ESPECIALLY ALONG AND EAST OF THE I-69C/HWY 281 CORRIDOR.
TROPICAL MOISTURE BEGINS TO SURGE INTO DEEP SOUTH TEXAS LATE TONIGHT
AS PRECIPITABLE WATER VALUES APPROACH 2 INCHES BY TUESDAY
MORNING...MAINLY NEAR THE COAST. WILL MENTION SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS ALONG THE COAST AFTER MIDNIGHT...AND A
CHANCE OF CONVECTION AREA WIDE FOR TUESDAY. ALSO WITH THE HIGHER
MOISTURE CONTENT...LOCALLY HEAVY RAINFALL IS POSSIBLE ON TUESDAY.

HIGH TEMPERATURES TODAY WILL RANGE FROM THE 80S ALONG THE
BEACHES...THE LOW TO MID 90S ACROSS THE VALLEY AND THE MID TO UPPER
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. HIGH TEMPERATURES TUESDAY WILL BE A FEW DEGREES LOWER
THAN TODAY DUE TO THE ABUNDANT CLOUD COVER AND THE INCREASE IN RAIN
CHANCES.

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...THE OVERALL SYNOPTIC
TREND FROM OVER THE LAST SEVERAL DAYS HAS REMAINED FAIRLY
UNCHANGED. A LARGE 500 MB RIDGE REMAINS ENCTRENCED OVER THE
WESTERN STATES WITH A PRETTY DEEP TROUGH PREVAILING OVER THE
EASTERN STATES. THIS CONFIGURATION KEEPS DEEP SOUTH TX UNDER A
FAIRLY WEAK PATTERN WITH SURGES OF DEEPER LAYER TROPICAL MOISTURE
STARTING TO ADVECT UP FROM SOUTH TO NORTH OVER NORTHEASTERN MEXICO
AND SOUTHERN TX. THE ECMWF ALSO REFLECTS DEVELOPMENT OF A BROAD
500 MB CLOSED LOW CLOSE TO OR TO THE SOUTH OF THE RGV WHILE THE
GFS SHOWS A BROADER LOW LOCATED FURTHER SOUTH OF THE RGV THAN THE
ECWMF. BOTH OF THESE MODELS TEND TO DRIFT THIS CLOSED LOW/TROUGH
GRADUALLY WESTWARD AROUND THE BASE OF THE WESTERN RIDGE AXIS BY
NEXT WEEKEND. THIS OVERALL TREND INDICATES THAT DEEP SOUTH TX WILL
SEE A SHIFT BACK TO A GENERALLY WETTER PATTERN FOR MOST OF THE
UPCOMING WEEK. HOWEVER THE BIG QUESTION STILL REMAINS AS WHICH
LONGER RANGE MODEL WILL VERIFY BETTER FOR POPS. SINCE THE GFS
KEEPS THE 500 MB TROFFING/CLOSED LOW A LITTLE FURTHER SOUTH OVER
MEXICO WITH THE RGV STAYING ON THE NORTHERN PERIPHERY OF THE
DEEPER LAYER MOISTURE THE MEX MOS POPS ARE LOWER VERSUS THE ECMWF
WHICH KEEPS THE TROPICAL MOISTURE POOL CLOSER TO THE RGV. SO
DECIDED TO GO WITH A GENERAL 50/50 BLEND OF THE GFS AND ECMWF
MODEL POPS THROUGH DAY 7.

THE STRATEGY FOR THE FORECAST TEMPS IN THE LONGER RANGE WILL BE
PRETTY STRAIGHT FORWARD. WITH BOTH MODELS SHOWING A GENERALLY
WETTER PATTERN EXPECT CLD COVER TO BE MORE WIDESPREAD WHICH WILL
TEND TO HOLD DOWN THE TEMPS CLOSER TO CLIMO FOR EARLY JULY. SO
WENT WITH A MODEL BLEND FOR MAXES AND MINS THROUGH DAY 7 MAYBE
LEANING CLOSER TO THE SLIGHTLY COOLER ECMWF NUMBERS.

THE RUN TO RUN CONSISTENCY WITH THE GFS MEX MOS TEMPS AND POPS
LOOKS OK FOR BOTH TEMPS AND POPS. OVERALL FORECAST CONFIDENCE AT
THIS TIME IS DECENT DESPITE THE PERSISTENT MODEL DIFFERENCES
SHOWING UP LATER IN THE FORECAST PERIOD.

.MARINE /NOW THROUGH TUESDAY/...LIGHT TO MODERATE SOUTH TO
SOUTHEAST WINDS PREVAIL ALONG THE LOWER TEXAS COAST THIS MORNING.
BUOY 42020 CURRENTLY REPORTING SOUTHEAST WINDS AT 14 KNOTS WITH
SEAS OF 3.3 FEET. BROAD HIGH PRESSURE OVER THE NORTHERN GULF WILL
PROVIDE GENERALLY FAVORABLE MARINE CONDITIONS FOR TODAY. THE
GRADIENT WILL BEGIN TO TIGHTEN TONIGHT AND TUESDAY RESULTING IN
INCREASING WINDS AND SLIGHTLY HIGHER SEAS. SMALL CRAFT EXERCISE
CAUTION IS POSSIBLE ON THE GULF WATERS TONIGHT DUE TO INCREASING
WINDS.

TUESDAY NIGHT THROUGH FRIDAY...MODERATE SURFACE RIDGING WILL
REMAIN IN PLACE OVER THE GULF OF MEXICO THROUGH THE END OF THE
WORK WEEK WHICH WILL MAINTAIN A MODERATE SE WIND REGIME OVER THE
LOWER TX BAY AND GULF WATERS. THIS WILL MAINTAIN FAIRLY ELEVATED
SEAS THROUGH FRI WITH SOME SCEC/MARGINAL SCA CONDITIONS POSSIBLE.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  91  79  89  79 /  20  20  50  40
BROWNSVILLE          92  79  90  78 /  20  20  50  40
HARLINGEN            94  77  92  76 /  20  10  50  40
MCALLEN              96  78  93  77 /  20  10  50  40
RIO GRANDE CITY      97  77  95  75 /  10  10  50  30
SOUTH PADRE ISLAND   88  80  87  80 /  20  20  50  50

&&

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

$$

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

SHORT TERM...60
LONG TERM...63
GRAPHICAST/UPPER AIR...65



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