Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 221008
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
408 AM CST SAT NOV 22 2014

.SHORT TERM /TODAY THROUGH SUNDAY/...DIFFICULT FORECAST IN THE OFFING
WITH THE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS LATE TODAY
INTO THE EVENING. POTENT MID LEVEL TROUGH/LOW BEGINNING TO PICK UP
FORWARD MOMENTUM AS IT DIVES INTO NORTHERN MEXICO JUST SOUTH OF
THE NEW MEXICO BOOTHEEL. MODELS ARE IN GOOD AGREEMENT TRACKING THE
TROUGH OVER SOUTH CENTRAL TEXAS THROUGH THE EVENING AND EAST OF
THE GULF COAST AFTER MIDNIGHT. THE POSITION OF THE MID LEVEL
TROUGH PLACES DEEP SOUTH TEXAS ON THE SOUTH SIDE WITH THE
STRONGEST MID AND UPPER LEVEL JET PASSING OVER THE REGION. LARGE
SCALE ASCENT IS ANTICIPATED AS THIS JET APPROACHES AND MOVES
OVERHEAD. MOISTURE CONTINUES TO DEEPEN AT ALL LEVELS WITH THE LOW
LEVEL JET/SOUTHEASTERLIES STRENGTHENING/AND THE SUBTROPICAL JET
SEEN STREAMING IN FROM THE PACIFIC. LOOKING AT THE CURRENT RADAR
TRENDS SHOWERS AND ISOLATED THUNDERSTORMS ARE INCREASING WITH BOTH
THE LOW LEVEL SE AND THE MID/UPPER LEVEL SW FLOW. MOISTURE, LIFT
ARE IN PLACE NOW WE NEED THE INSTABILITY. PREVIOUS DISCUSSION
MENTIONS STRONG SOUTHWESTERLIES AT 700MB DEVELOPING IN ADVANCE OF
THE MID LEVEL TROUGH. THIS IS STILL EXPECTED PRIOR TO MAIN IMPACT
OF THE JET DYNAMICS AND MAY INITIALLY LIMIT THUNDERSTORM ACTIVITY
OVER THE RGV THIS AFTERNOON. ANOTHER INHIBITING FACTOR MAY BE TOO
MUCH CLOUD COVER TO INCREASE SURFACE BASE INSTABILITY. HOWEVER THE
LARGE SCALE ASCENT LOOKS TO BE STRONG ENOUGH AS THE TROUGH MOVES
INTO THE REGION TO OVER COME THE LIMITING CAPPING INVERSION.
LOOKING AT ALL FACTORS BELIEVE THERE STILL WILL BE A SLIGHT CHANCE
FOR STORMS OR A LINE OF STORMS TO PRODUCE STRONG GUSTY WINDS.

FOR TODAY...SCATTERED SHOWER AND THUNDERSTORMS TO START OFF THE DAY
WITH ACTIVITY TAPERING OFF ACROSS THE MID AND LOWER VALLEY AS THE
CAPPING INVERSION TAKES HOLD. MOSTLY CLOUDY SKIES MAY BREAK ENOUGH
IN THE AFTERNOON TO ALLOW FOR BIT MORE SUNSHINE PUSHING TEMPERATURES
INTO THE LOWER 80S. AS FOR THE WIND STILL EXPECTING A BREEZY TO
WINDY DAY AS LOW LEVEL JET STRENGTHENS TO AROUND 35KNOTS. THE
BOUNDARY LAYER IS NOT EXPECTED TO MIX COMPLETELY WITH CLOUDS AND
LIMITED HEATING KEEPING THE FULL WIND POTENTIAL FROM REACHING THE
SURFACE. SO NO WIND ADVISORY BUT SOME GUSTS BETWEEN 30-35 MPH ARE
POSSIBLE.

LATE THIS AFTERNOON AND EVENING THROUGH MIDNIGHT WILL BE LOOKING
WESTWARD AS THUNDERSTORMS GETTING GOING OVER SOUTH CENTRAL TEXAS AND
THE HILL COUNTRY. SPC CONTINUES TO PLACE ALL OF SOUTH CENTRAL AND
SOUTHEAST TEXAS INCLUDING OUR CWA UNDER A SLIGHT RISK OF SEVERE
THUNDERSTORMS. THE INITIAL WAVE OF THUNDERSTORMS TO TRANSITION INTO
A MORE ORGANIZED SQUALL LINE OF SORTS AS THE DIVERGENT FLOW
INCREASES ALONG THE LEADING EDGE OF THE SURFACE BOUNDARY. TIMING OF
THE LINE OF THUNDERSTORMS TO MOVE ACROSS THE CWA IS 6 PM TO 10 PM
AND IT IS AT THIS TIME THAT SEVERE WEATHER WILL HAVE ITS GREATEST
POTENTIAL. MAIN IMPACTS WILL BE STRONG GUSTY WINDS /50-60 MPH/EITHER
WITH INDIVIDUAL CELLS ALONG THE LINE OR ALL ALONG THE LINE AS IT IS
EXPECTED TO BE MOVING RATHER QUICKLY EASTWARD.

AFTER MIDNIGHT AND SUNDAY...IF SQUALL LINE TIMING REMAINS IN PLACE
THE LINE WILL BE MOVING OFFSHORE SHORTLY BEFORE OR AROUND MIDNIGHT.
SOME LINGERING RAIN SHOWERS AND ELEVATED THUNDERSTORM IS POSSIBLE
ALONG THE COASTAL REGIONS CLOSE TO MIDNIGHT BEFORE WESTERLY WINDS
TAKE OVER AND BEGIN DRYING OUT AND STABLIZING THE LOW LAYERS. COOLER
TEMPERATURES TO RESULT OVERNIGHT. SUNDAY WILL BE QUIET PLEASANT AND
WARM WITH A DOWNSLOPING WESTERLY FLOW AND FULL SUNSHINE.
TEMPERATURES TO WARM INTO THE LOW TO MID 80S AND HUMIDITY LEVELS
WILL BE MUCH MORE COMFORTABLE.

.LONG TERM /SUNDAY NIGHT - FRIDAY/...ON THE WHOLE A CHAMBER OF
COMMERCE WEEK FOR THE RIO GRANDE VALLEY WHICH IS A NICE CHANGE OF
PACE FROM THE RECENT FLIP-FLOP PATTERN FROM SUMMER TO WINTER AND
BACK AGAIN. DEEP DRY AIR RESIDENT ACROSS THE SOUTHWEST U.S. AND
NORTHERN MEXICO...AIDED BY PERSISTENT 500 MB RIDGING IN THIS AREA
WITH NORTHWEST TO WEST-NORTHWEST FLOW NUDGING THE MASS OF DRY AIR
ACROSS MOST OF TEXAS THROUGH THE PERIOD. BOTTOM LINE? A GREAT WEEK
TO ENJOY THE REGION FOR THOSE PLANNING VISITS FOR THE THANKSGIVING
HOLIDAY AND TRAVEL PERIOD.

FOR THE SENSIBLE WEATHER...THE AFOREMENTIONED WARM TO HOT SUNDAY
WILL RECEDE TO FAIRLY AVERAGE TEMPERATURES SUNDAY NIGHT INTO EARLY
MONDAY /50S TO NEAR 60/. ECMWF AND GFS DIFFER A BIT ON THE ARRIVAL
OF COOLING NORTHERLY FLOW...BUT THE END RESULT IS A SEASONABLE DAY
WITH PERHAPS A FEW PERIODS OF BROKEN CLOUDS NEAR THE COAST
THROUGH MID DAY BUT ENOUGH SUNSHINE TO TAKE THE EDGE OFF THE
SLIGHTLY BREEZY MIDDAY THROUGH MID AFTERNOON.

WINDS SLACKEN MONDAY NIGHT AHEAD OF A MUCH MORE VIGOROUS WAVE
WHICH ARRIVES AND DIVES THROUGH TEXAS TUESDAY MORNING. WITH MOSTLY
CLEAR SKIES FOR MOST AREAS MOST OF THE NIGHT EXPECT TEMPERATURES
TO DIP INTO THE UPPER 40S TO LOWER 50S...A FEW DEGREES BELOW LATE
NOVEMBER AVERAGES. COULD SEE A PERIOD OF BROKEN CLOUDS NEAR THE
COAST AT DAYBREAK AS ENERGY ATTEMPTS TO BRING MOISTURE BACK BELOW
700 MB BUT FOR NOW HAVE SKY COVER AS PARTLY CLOUDY.

AS FOR TUESDAY...GFS AND ECWMF IN REMARKABLE AGREEMENT WITH TIMING
AND MOVEMENT OF THE EMBEDDED SHORT WAVE. THE TAKEWAY IS THE
ATMOSPHERIC COOLING...WITH 1000-500 MB THICKNESS DIPPING TO
546-552 DM FROM THE COASTAL BEND THROUGH THE RGV BY LATE
AFTERNOON/EARLY EVENING AND 850 TEMPERATURES SLIPPING TOWARD 4-6C
IN THE SAME AREA. TIME HEIGHT SECTIONS SHOW FAIRLY VIGOROUS
NORTH/NORTHWEST FLOW OFF THE DECK...SOME WHICH WILL TRANSLATE DOWN
TOWARD THE SURFACE AND COULD PRODUCE BREEZIER CONDITIONS THAT
CURRENTLY ADVERTISED BY MODEL BLENDS. FOR NOW...HAVE SUSTAINED
WINDS IN THE 10-15 KNOT RANGE DURING THE AFTERNOON BUT WOULD NOT
SURPRISE TO SEE THESE VALUES RAMPED UP TOWARD 15-20 KNOTS ON LAND
OVER THE NEXT DAY OR TWO. THOUGH THE ATMOSPHERE COOLS...SUNSHINE
DOMINATES BY AFTERNOON AND WITHOUT A POLAR FEED EXPECT
TEMPERATURES TO TRIM BACK BELOW AVERAGE BUT STILL ACHIEVE THE
LOWER 70S VALLEY AND AROUND 70 RANCHLANDS...A NICE DAY ESPECIALLY
FOR THOSE ARRIVING FROM THE UPPER MIDWEST AND THE NORTHERN PLAINS.

WINDS SHOULD LAY DOWN TUESDAY NIGHT LEADING TO A CLEAR BUT CHILLY
MORNING WEDNESDAY...BUT NOTHING CLOSE TO FREEZING AT THIS POINT
/UPPER 30S TO MID 40S OVERALL/. CHAMBER OF COMMERCE DAY WEDNESDAY ACROSS
TEXAS AS STRONG BUT PLEASANT HIGH PRESSURE SETTLES IN...ABOUT AS
GOOD A TRAVEL DAY AS ONE CAN EXPECT. THANKSGIVING DAY LOOKS
FANTASTIC AS WELL AND A SHADE WARMER AFTER ANOTHER CHILLY START
WITH WINDS VEERING TO THE SOUTH/SOUTHEAST BUT STILL LIGHT ENOUGH
TO ENJOY.

ECMWF/GFS FOR THIS CYCLE HAVE COME INTO AGREEMENT WITH CONTINUED
LIGHT SOUTHERLY FLOW INTO FRIDAY...WITH A GRADUAL INCREASE IN
MOISTURE LEADING TO FAIR WEATHER CUMULUS NEAR THE COAST DURING THE
AFTERNOON. TEMPERATURES SHOULD REMAIN SIMILAR TO THURSDAY...75 TO
80 OVERALL WITH PLENTY OF SUNSHINE EVEN WHERE SOME OF THE CLOUDS
FORM UP.

&&

.MARINE...TODAY THROUGH SUNDAY...SMALL CRAFT ADVISORIES TO REMAIN IN
PLACE TODAY WITH MARGINAL CONDITIONS OVER THE LAGUNA MADRE. STORM
SYSTEM DEVELOPING OVER WESTERN TEXAS TO KEEP A STRONG GRADIENT
ACROSS THE GULF WATERS BUT COOLER BAY WATERS TO LIMIT THE WIND
POTENTIAL ACROSS MUCH OF THE LAGUNA. GRADIENT DOES WEAKEN LATE
TODAY BUT RESIDUAL SEAS TO REMAIN HIGH. EXPECTING STRONG
THUNDERSTORMS TO FORM OVER INLAND AREAS DURING THE EARLY EVENING
HOURS MOVING OFFSHORE AROUND 9 PM AND RACING ACROSS THE COASTAL
WATERS EXITING THE REGION AROUND OR SHORTLY AFTER MIDNIGHT.
IMPROVING MARINE CONDITIONS SUNDAY WITH LIGHT WESTERLY WINDS AND
STEADILY LOWERING SEAS.

SUNDAY NIGHT THROUGH WEDNESDAY: LIGHT WINDS AND SLIGHT TO MODERATE
SEAS SUNDAY NIGHT WILL INCREASE TO CAUTION LEVELS...15 TO 20 KNOTS
WITH SEAS BUILDING TOWARD 6 FEET WITH FRONT NUMBER ONE ON MONDAY.
AFTER A BRIEF QUIETING MONDAY NIGHT THE AFOREMENTIONED UPPER
DISTURBANCE WILL PUSH A REINFORCING SHOT...FRONT NUMBER TWO...OF GUSTY
NORTHERLY WINDS TUESDAY AFTERNOON INTO EARLY EVENING...PERHAPS
REACHING 20 KNOTS WITH SEAS BUILDING TOWARD 7 FEET IN A FEW SPOTS.

AS QUICKLY AS WINDS AND SEAS RISE THEY`LL BE DIMINISHING/SUBSIDING
AGAIN TUESDAY NIGHT AND ESPECIALLY WEDNESDAY...SETTING UP QUITE
NICELY FOR THOSE PLANNING PRE-THANKSGIVING BOATING/FISHING TRIPS
INTO THE BAY OR GULF. STILL A HINT OF 5 FOOT SEAS WELL OFFSHORE
WEDNESDAY...BUT INSHORE/NEARSHORE WATERS SHOULD BE DELIGHTFUL.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  79  64  82  59 /  30  60   0   0
BROWNSVILLE          80  64  84  59 /  30  60   0   0
HARLINGEN            81  62  84  58 /  30  60   0   0
MCALLEN              82  62  86  58 /  20  40   0   0
RIO GRANDE CITY      84  59  87  57 /  30  50   0   0
SOUTH PADRE ISLAND   78  67  79  64 /  30  60   0   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR GMZ150-155-
     170-175.

&&

$$

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

SHORT TERM...59/GB
LONG TERM...52/BSG
MARINE...59/52
GRAPHICASTS...CAMPBELL





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