Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 130659 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
159 AM CDT SUN APR 13 2014

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

&&

.AVIATION...IR SATL IMAGERY SHOWS TWO CLD LAYERS OVER THE RGV AT
THE MOMENT. SCT TO BKN CIRRUS DECKS CONTINUE TO ADVECT OVER THE
AREA FROM WEST TO EAST. AT THE LOWER LEVELS RAGGED STRATUS DECKS
HAVE BEEN MOVING UP FROM THE SOUTH CAUSING PERIODIC REDUCTIONS TO
CEILINGS FOR ALL OF THE LOWER RGV AIRPORTS. EXPECT THE LOWER CLD
DECKS TO CONTINUE PLAGUING THE AREA THROUGHOUT THE EARLY MORNING
HOURS. AFTER SUNRISE THE STRONGER S-SE LOW LEVEL WINDS WILL MIX
DOWN TO THE SURFACE WHICH WILL TEND TO ERODE AWAY THE LOWER
CEILINGS ALLOWING FOR MVFR/VFR CONDITIONS TO RETURN LATER IN THE
MORNING AND CONTINUING INTO THE AFTERNOON HOURS. LOWER CEILINGS
WILL BE EXPECTED ONCE AGAIN LATE IN THE TAF PERIOD AS THE LAYER
FROM 950 MB DOWN TO THE SURFACE MOISTENS UP AFTER SUNSET. THIS
WILL ALLOW A RETURN OF MVFR/IFR CEILINGS LATE IN THE PERIOD.

&&

.PREV DISCUSSION... /ISSUED 653 PM CDT SAT APR 12 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...MVFR CIGS EXPECTED MOST OF THIS TAF PERIOD AT KBRO AND
KHRL AND A LITTLE LATER TONIGHT AT KMFE. CIGS WILL LOWER THROUGH
THE NIGHT AND IFR CIGS POSSIBLE CLOSER TO DAWN. SOUTHEASTERLY
WINDS WILL CONTINUE THIS PERIOD...GUSTY INITIALLY THEN LOSING THE
GUSTS TOWARDS MID EVENING. WILL NEED TO WATCH CLOSELY FOR WIND
SHEAR OVERNIGHT DEPENDING ON WHAT SFC WINDS DO. GUSTS RETURN AFT
15Z.

PREV DISCUSSION... /ISSUED 204 PM CDT SAT APR 12 2014/

SHORT TERM.../TONIGHT THROUGH SUNDAY NIGHT/...AN OPEN WAVE OVER THE
DESERT SOUTHWEST IS SUPPORTING PRESSURE FALLS OVER THE SOUTHERN HIGH
PLAINS. THIS WILL KEEP LOCAL WINDS FROM THE SOUTH SOUTHEAST ON THE
BREEZY SIDE THROUGH TONIGHT AND SUNDAY. OVERNIGHT TEMPS WILL BE IN
THE LOWER 70S WITH MOSTLY CLOUDY SKIES...INCLUDING A MIX OF LOW
CLOUDS AS WELL AS HIGHER CIRRUS MOVING FROM WEST TO EAST IN THE
SUBTROPICAL JET. WINDS WILL DECREASE TO MODERATE TONIGHT ALLOWING
LIGHT PATCHY FOG TO FORM...BUT LOW CLOUDINESS WILL BE THE MAIN
CONSIDERATION.

SUNDAY...MOISTURE MOVING NORTH OVER THE WEST GULF WILL BRING ISOLD
COASTAL SHOWERS TO THE LOWER TEXAS COAST AND MARINE AREAS FOR THE
DAY...AS WINDS INCREASE AGAIN TO BREEZY FROM THE SOUTH SOUTHEAST.
MOSTLY CLOUDY SKIES WILL AGAIN BE THE RULE WITH HIGH TEMPERATURES
FROM THE 80S NEAR THE COAST TO THE MID 90S INLAND WEST. THE PLAINS
LOW WILL EJECT NORTHEAST WHILE ANOTHER SHORT WAVE TROUGH DIGS SOUTH
ALONG THE ROCKIES...WITH COLDER HIGH PRESSURE MOVING OUT OF CANADA
AND SOUTH ACROSS THE PLAINS. THE CANADIAN AIR MASS WILL ORIGINATE IN
THE NORTHWEST...BUT TEMPS THERE ARE IN THE TEENS FAHRENHEIT...MUCH
TOO WARM TO BE CALLED ARCTIC AT THIS POINT IN THE YEAR.

SUNDAY NIGHT...THE COLD FRONT WILL ADVANCE INTO TEXAS...BUT WILL BE
TOO FAR NORTH TO HAVE ANY SIGNIFICANT IMPACT. LOCAL WINDS MAY RELAX
A BIT AS THE GRADIENT IS EXTINGUISHED. MOISTURE WILL RISE...FROM A
PWAT OF AROUND AN INCH NOW TO ABOUT AN INCH AND A HALF BY SUNDAY
NIGHT. ELEVATED DEW POINTS WILL PROP OVERNIGHT LOWS UP IN THE 70S...
WITH CLOUDY SKIES AND WIDER COVERAGE BY LIGHT FOG THAN SATURDAY
NIGHT.

LONG TERM.../MONDAY THROUGH SATURDAY/...ALL MODEL TRENDS CONTINUE
TO INDICATE A PRETTY SIGNIFICANT COLD FRONT TO MOVE THROUGH THE
CWA MONDAY AFTERNOON. CONFIDENCE REMAINS AVERAGE TO ABOVE AVERAGE
WITH MODEL CONSISTENCY IN GOOD AGREEMENT THROUGH WEDNESDAY. BEYOND
WEDNESDAY MODELS BEGIN TO DIVERGE THEIR SOLUTIONS SO A PERSISTENT
WILL BE THE BEST FORECAST UNTIL MODELS COME BETTER IN LINE.

MONDAY...LOOKING FOR FOR ATMOSPHERE TO DESTABILIZE AS THE FRONT
APPROACHES THE NORTHERN RANCHLANDS SHORTLY AFTER NOON. THEN CONTINUE
ITS STEADY TRACK SOUTH MOVING THROUGH MID VALLEY AROUND 3 TO 4 PM
AND LOWER VALLEY 5 TO 6 PM. SOUTH TO SOUTHWEST FLOW AT 850-700MB TO
WARM ATMOSPHERE PROVIDING A MORNING CAP WHICH SLOWLY ERODES DURING
THE AFTERNOON. TEMPERATURES TO PEAK PRIOR TO FRONTAL PASSAGE AND
MIGHT SPIKE ACROSS THE MID AND LOWER VALLEY IF MORNING LOW CLOUDS
BREAK UP SUFFICIENTLY. DID RAISE TEMPERATURES IN THE LOWER 90S IN
THE LOWER VALLEY AND MAYBE NOT ENOUGH IN THE MID VALLEY. THIS WILL
ALSO BE HIGHLY DEPENDENT ON TIMING OF THE FRONT. SPC HAS PLACED
THE CWA UNDER A GENERAL THUNDERSTORM OUTLOOK. THIS LOOKS ON TRACK
WITH LAPSE RATES REMAINING ON THE LOWER END AND MAIN DIVERGENT FLOW
AND UPPER DISTURBANCE REMAINING TO OUR NORTH AND EAST. FRONTAL
LIFT AND MODEST INSTABILITY /AVE. CAPE OF 1000-2000 J/KG/ SHOULD
BE SUFFICIENT FOR SCATTERED THUNDERSTORMS WITH ONE OR TWO BECOMING
STRONG ENOUGH TO PRODUCE SOME WIND GUSTS AND BRIEF HEAVY
DOWNPOURS. OTHER ISSUE WILL STRONG GRADIENT BEHIND THE FRONT WITH
NORTH WINDS INCREASING RIGHT BEHIND THE FRONT TO 20-25 MPH AND
GUSTY. WINDS DO NOT ABATE MUCH AND MAY EVEN INCREASE OVERNIGHT AS
GFS AND NAM SHOW 35-45 KNOT JET MAX AT 925-850MB COUPLED WITH
DOWNWARD OMEGA. THE STRONGEST GRADIENT IS ALONG AND EAST OF THE
HIGHWAY 77/69E AND OUT OVER THE COASTAL WATERS. WESTERN AREAS WILL
LIKELY SEE BREEZY CONDITIONS A FEW HOURS BEHIND THE FRONT WHILE
THE COASTAL COUNTIES WILL LIKELY SEE GUSTS OVER 30 MPH MONDAY
NIGHT. FOR OUR MARINE AREAS WILL LIKELY BE ENTERTAINING A GALE
WATCH THIS TIME TOMORROW FOR THE MONDAY NIGHT PERIOD WITH THE
STRENGTHENING GRADIENT BUT TO EARLY AT POINT IN TIME TO ISSUE.

TEMPERATURES TO FALL 10 DEGREES OR MORE WITHIN A FEW HOURS AFTER
FRONTAL PASSAGE AND CONTINUE TO FALL WITH GOOD COLD AIR ADVECTION.
MODEL CONSENSUS AVERAGES A FEW DEGREES LOWER THEN PREVIOUS
FORECAST MINIMUMS FOR TUESDAY MORNING EVEN WITH THE STRONG
SURFACE WINDS. UPDATED FORECAST ALSO TRENDS IN THIS THE LOWER
DIRECTION. CAA CONTINUES TUESDAY AND TEMPERATURES MIGHT HAVE A
TOUGH TIME BREAKING 70 IN THE EAST. SOME MID CLOUD TO LIMIT
SUNSHINE IN THE MORNING BUT MODEL SOUNDING SHOW DRIER AIR WORKING
ITS THROUGH ALL LEVELS OF THE ATMOSPHERE ALLOW FOR PLENTY OF SUN
IN THE AFTERNOON. SURFACE HIGH PRESSURE SETTLES ALONG THE COAST
TUESDAY NIGHT SETTING UP EXCELLENT RADIATIONAL COOLING FOR
WEDNESDAY MORNING. ANOTHER RATHER COOL TO COLD MORNING WITH
TEMPERATURES 15 DEGREES BELOW NORMAL. RECORDS ARE NOT IN JEOPARDY
AT THIS TIME WITH RECORDS SET AROUND 40 DEGREES AT BOTH
BROWNSVILLE AND HARLINGEN.

WARM UP BEGINS WEDNESDAY AFTERNOON BUT STILL COMFORTABLE INTO
THURSDAY AS RETURN FLOW WILL BE SLOW IN BECOMING ESTABLISHED.
REMAINDER OF THE FORECAST IS UNCHANGED AS MODELS DIFFER HIGHLY IN
THEIR SOLUTIONS. GFS SHOWS ANOTHER STRONG TROUGH MOVING INTO THE 4
CORNERS THURSDAY PUSHING A COLD FRONT THROUGH THE REGION LATE
FRIDAY. 00Z ECMWF SHOWS A TROUGH OVER THE NORTHERN ROCKIES WITH NO
FRONT IN THE REGION. CANADIAN IS SIMILAR TO THE GFS BUT FARTHER
NORTH. CONFIDENCE IS BELOW AVERAGE ON THE UPSTREAM SYSTEM SO WILL
MAINTAIN THE STEADY WARM UP AND KEEP FORECAST DRY THROUGH THE END
OF NEXT WEEK.

MARINE...TONIGHT THROUGH SUNDAY NIGHT...HIGH PRESSURE OVER THE NORTH
GULF OF MEXICO WILL INTERACT WITH DEEPENING LOW PRESSURE OVER THE
SOUTHERN HIGH PLAINS TO YIELD ELEVATED SOUTH SOUTHEAST WINDS AND
BORDERLINE SMALL CRAFT ADVISORY CONDITIONS TONIGHT. THE PRESSURE
FALLS OVER THE SOUTHERN HIGH PLAINS WILL OCCUR IN ADVANCE OF MID
LEVEL TROUGHING MOVING WEST TO EAST OVER THE SOUTHWEST UNITED
STATES. THE GRADIENT WILL SUPPORT 15 TO 20 KT WINDS SUNDAY AND
EVEN SUNDAY NIGHT...AHEAD OF A COLD FRONT OF ARCTIC AIR MASS
ORIGINS MOVING INTO NORTH TEXAS. GULF WATER TEMPERATURES ARE IN
THE MID TO UPPER 60S...COOL ENOUGH TO PROVIDE SOME DAMPING EFFECT
TO THE SYNOPTIC SCALE FORCING. THIS TENDS TO BE BEST NOTED NEAR
THE COAST...WHERE DAY TIME WINDS ON OR NEAR PADRE ISLAND CAN BE
LOWER BY 5 TO 10 MPH THAN WOULD OTHERWISE BE EXPECTED.

MONDAY THROUGH THURSDAY...STRONG COLD FRONT FOR MID APRIL TO MOVE
THROUGH THE COASTAL WATERS LATE MONDAY AFTERNOON. GRADIENT TO
STRENGTHEN MONDAY NIGHT INTO TUESDAY MORNING WITH A POSSIBLE WATCH
AS WIND GUSTS COULD EXCEED GALE FORCE WITH A 35 TO 40 KNOT
NORTHERLY JET OVER THE WESTERN GULF. STRONG NORTH WINDS CONTINUE
THROUGH TUESDAY AFTERNOON BEFORE SURFACE HIGH PRESSURE BUILDS
ALONG THE COAST TUESDAY NIGHT ALLOW FOR MARINE CONDITIONS TO
IMPROVE. SOUTHEAST WINDS TO RETURN GRADUALLY WEDNESDAY INTO
THURSDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  84  73  88  53 /  20  10  40  30
BROWNSVILLE          85  73  90  53 /  20  10  40  30
HARLINGEN            88  73  91  50 /  20  10  40  30
MCALLEN              90  73  90  51 /  10  10  40  20
RIO GRANDE CITY      94  72  88  52 /  10  10  40  20
SOUTH PADRE ISLAND   79  72  76  55 /  20  10  40  30

&&

.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





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