Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 271800
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
100 PM CDT SAT JUN 27 2015

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

&&

.AVIATION...A FEW ISOLATED SHOWERS ARE DEVELOPING OVER THE COAST
AND EXTEND SOUTH TOWARDS BROWNSVILLE. AN AREA OF LOW LEVEL
CONVERGENCE WILL CONTINUE TO ENHANCE THIS SHOWERS NEAR THE COAST.
INCLUDED A TEMPO GROUP FOR KBRO WHERE THERE IS HIGHER POTENTIAL
TO SEE SOME CONVECTION THAT FAR WEST THIS AFTERNOON. DUE TO DRY
AIR ACROSS THE AREA AND UPPER LEVEL CONFLUENCE ALOFT ENHANCING
SUBSIDENCE WILL LIMIT THE POTENTIAL FOR RAIN EVERYWHERE WEST OF
HRL. SOUTHERLY FLOW WILL CONTINUE THROUGH THE AFTERNOOON AND
DECOUPLE A FEW HOURS AFTER SUNSET. THE WINDS WILL REMAIN LIGHT
OVERNIGHT WITH VFR CONDITIONS. INTO SUNDAY...SOUTHEAST WINDS BEGIN
TO INCREASE AS DAYTIME HEATING BEGINS BUT VFR CONDITIONS THROUGH
MID MORNING. THE MOISTURE CONTENT INCREASES ALLOWING FOR A CHANCE
OF SHOWERS BY MID AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 654 AM CDT SAT JUN 27 2015/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...IR SATL IMAGERY SHOWS GENERALLY CLEAR SKIES ACROSS
THE RGV WITH SOME MID AND HIGH LEVEL CLD COVER ADVECTING SOUTH OUT
WEST. THE 00Z BRO SOUNDING SHOWING A FAIRLY DRY PWAT OF 1.73
INCHES. EXPECT THE FAIRLY DRY AND STABLE CONDITIONS TO CONTINUE
THROUGH THE MORNING AND EVENING HOURS INDICATED BY THE LIMITED
NAM RH FIELDS. SOME FAIR WX CU/SC WILL DEVELOP LATER THIS MORNING
AND THIS AFTERNOON AS THE DAYTIME HEATING KICKS IN. SO WILL GO
WITH VFR CONDITIONS FOR ALL THREE RGV AIRPORTS THROUGH THE NEXT 24
HOURS.

PREV DISCUSSION... /ISSUED 432 AM CDT SAT JUN 27 2015/

SHORT TERM /TODAY THROUGH SUNDAY/...AS THE 500 BM TROFFING DIGS
OVER THE MID MISS RIVER/OHIO RIVER VALLEY SAT AND SAT NIGHT AN
AREA OF PV WILL PUSH INTO SOUTH CENTRAL TX WITH SOME BETTER
MOISTURE VALUES ALSO ADVECTING SLOWLY SOUTHWARDS THROUGH THE SHORT
TERM PERIOD. AS THIS PV AND MOISTURE PUSHES SOUTHWARDS EXPECT THE
POPS TO START REBOUNDING SAT NIGHT INTO SUN. THE DAYTIME HEATING
AND SOME POTENTIAL SEA BREEZE EFFECTS COULD RESULT IN SOME CHC
POPS ESPECIALLY LATE SUN MORNING INTO THE AFTERNOON HOURS.

FOR TEMPS WILL GO WITH A LITTLE WARMER TEMPS TODAY VERSUS SUNDAY
SINCE THE SLIGHTLY HIGHER POPS ON SUN WILL RESULT IN A LITTLE
LOWER HIGH TEMPS. THE FORECAST HIGHS AND LOWS WILL BE A GENERAL
BLEND OF THE MET/MAV AND ECS MODELS.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...THE LARGE SCALE
SYNOPTIC PATTERN WILL FEATURE AN H5 RIDGE OVER THE WEST AND AN
OPPOSING H5 TROUGH OVER THE GREAT LAKES AND SOUTHEAST. THESE TWO
FEATURES WILL ERODE OR FLATTEN OVER TIME...WITH AN H5 WEAKNESS
DEVELOPING OVER NORTHEAST MEXICO DURING THE FIRST HALF OF THE
WEEK. A LOW HEIGHT CENTER AT H2 OVER THE WEST GULF WILL START OUT
THE LONG TERM BUT WILL FILL AND LOSE DEFINITION AFTER THAT. AS THE
BERMUDA RIDGE BUILDS OVER THE NORTHEAST GULF LATER IN THE WEEK...
THE H5 WEAKNESS WILL SHIFT WEST A BIT...WITH ITS AXIS MORE OVER
WEST TEXAS AND NORTH CENTRAL MEXICO. THOUGHT HE DOOR WILL STILL BE
OPEN TO MARINE BASED CONVECTION FROM THE SOUTH...POP CHANCES OVER
THE CWA SHOULD DIMINISH COMPARED TO MID WEEK.

THE RIDGE OVER THE WEST WILL ALLOW A VERITABLE PARADE OF FRONTS
TO MOVE SOUTHEAST OUT OF CANADA EARLY ON...AND ONE WILL STALL
ACROSS THE NORTH GULF COAST AND EXTEND BACK INTO EAST AND POSSIBLY
CENTRAL TEXAS JUST NORTH OF THE CWA SUNDAY NIGHT AND MONDAY...
WHERE IT WILL REMAIN. AS THE FRONT DISSIPATES MONDAY... MODELS
INDICATE MID LEVEL DRIER AIR INFILTRATING THE WESTERN GULF...
LOWERING RAIN CHANCES FOR MONDAY. WINDS...HOWEVER...WILL INCREASE
FROM THE SOUTH AND THIS MAY INCREASE LOW LEVEL MOISTURE ENOUGH TO
SUPPORT A SLIGHT CHANCE OF RAIN IN THE AFTERNOON.

MOVING AHEAD FROM THE WEEKEND INTO THE EARLY AND MID PART OF NEXT
WEEK...AS THE H5 TROUGH OVER THE EAST FILLS...HIGH PRESSURE WILL
BEGIN TO BUILD OVER THE GULF OF MX...EXTENDING INTO THE NORTHWEST
GULF. SOUTH WINDS WILL STRENGTHEN TUESDAY THROUGH THURSDAY...WITH
INCREASING MOISTURE. RH VALUES IN THE SFC TO H5 LAYER WILL BE 50
TO 75 PERCENT AS A PULSE OF MOISTURE MOVES UP FROM THE SOUTH. THE
GFS SHOWS TROPICAL MOISTURE SEEPING NORTH TUESDAY AND SURGING
INTO THE REGION WEDNESDAY AS PWAT APPROACHES TWO INCHES. MODEL
GUIDANCE INDICATES AN UPTICK IN POPS MID WEEK...AND THE INHERITED
FORECAST REFLECTS THAT WITH 30 TO 50 PERCENT VALUES TUESDAY AND
WEDNESDAY AND SLIGHTLY LESS ON THURSDAY. EXPECT A MIX OF CLOUDS
AND SUN MONDAY AND AFTER THURSDAY MORNING...BUT MORE CLOUDS THAN
SUN FOR THE MIDDLE OF THE WEEK.

IN SUMMARY...AN INCREASE IN MOISTURE...THE H5 WEAKNESS...AND
DAYTIME HEATING WILL ALL COMBINE TO MAINTAIN CONVECTIVE POTENTIAL
THROUGH THE LONG TERM. THE BEST CHANCE WILL BE TUE AND WEDNESDAY
AS RETURNING HIGH PRESSURE TRIGGERS THE ARRIVAL OF A BURST OF
MOISTURE FROM THE SOUTH. MODELS GUIDANCE REMAINS CONSISTENT IN
TEMPERATURES WITH LITTLE VARIATION BETWEEN THE ECMWF AND GFS...
REFLECTING NEAR SEASONAL NORMS OF 90S BY DAY AND 70S BY NIGHT.

MARINE...
NOW THROUGH SUNDAY...SURFACE OBS FROM THE BAY AND GULF WATERS
SHOW PRETTY STRONG SOUTH WINDS BLOWING AT 15 TO 20 KNOTS AT
BUOY020. WILL MENTION SOME SCEC WORDING FOR THE GULF WATERS THIS
MORNING. OTHERWISE THE MODERATE PGF PROVIDED BY THE SURFACE
RIDGING OVER THE WESTERN GULF OF MEX WILL MAINTAIN CONDITIONS
GENERALLY BELOW SCA LEVELS THROUGH TONIGHT AND SUNDAY.

SUNDAY NIGHT THROUGH WEDNESDAY...HIGH PRESSURE WILL EXTEND WEST
ACROSS THE GULF FROM THE ATLANTIC INTO THE NORTHWEST GULF...WITH
SLIGHTLY LOWER PRESSURE TO THE SOUTH ACROSS THE SOUTHWEST GULF.
HIGH PRESSURE WILL BUILD OVER THE NORTHWEST GULF EARLY IN THE
WEEK...CAUSING SOUTHEAST WINDS TO INCREASE AND WAVE HEIGHTS TO
GROW LARGER. OFFSHORE WINDS WILL APPROACH 20 KNOTS TUESDAY...
WITH WAVE HEIGHTS INCREASING TO AROUND SEVEN FEET TUESDAY AFTN
AND NIGHT. SMALL CRAFT ADVISORY CONDITIONS WILL BE POSSIBLE THEN.
SMALL CRAFT EXERCISE CAUITON CONDTIONS WILL BE MORE LIKELY MONDAY
NIGHT INTO TUESDAY MORNING...AND WEDNESDAY.

&&

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

$$

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