Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 281138 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
638 AM CDT THU MAY 28 2015

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

&&

.AVIATION...MULTI-LAYERED CLOUDS PRODUCING WIDESPREAD MVFR AND
PATCHY IFR CONDITIONS EARLY THIS MORNING. ISOLATED STREAMER
SHOWERS ARE TRACKING NORTH TO NORTHWEST AND MAY BRIEFLY BE IN
THE VICINITY OF THE AIR TERMINALS THROUGH 14Z. CLOUDS TO BREAK UP
AND LIFT THROUGH THE MORNING HOURS WITH VFR CONDITIONS THIS
AFTERNOON. SOUTHEAST WINDS. MODERATE SOUTHEAST WINDS WITH GUSTS
BETWEEN 20-25 KNOTS THIS AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 356 AM CDT THU MAY 28 2015/

SHORT TERM /NOW THROUGH FRIDAY/...MAIN CHALLENGE FOR THE SHORT
TERM IS THE POP FORECAST. WATER VAPOR LOOP INDICATES NEXT UPSTREAM
SHORTWAVE TROUGH EXTENDING FROM SW ARIZONA TO NEW MEXICO TRACKING
NORTHEAST OVER THE RIDGE PARKED OVER DEEP SOUTH TEXAS. MODELS
SUGGEST THE RIDGE GETS SHUNTED SOUTHWARD AS THE TROUGH MAKES ITS
WAY ACROSS TEXAS FRIDAY.

TODAY...ANOTHER HOT AND HUMID DAY WITH AN ISOLATED SHOWERS MOVING IN
FROM THE GULF EARLY THIS MORNING WITH A FEW SPRINKLES ACROSS THE
LOWER VALLEY. OTHERWISE...MORNING CLOUDS TO MIX OUT WITH PARTLY TO
MOSTLY CLOUDY SKIES THIS AFTERNOON. TEMPERATURES WARM TO NEAR
SEASONAL NORMAL WITH UPPER 80 TO MID 90S. MODERATE SOUTHEAST WINDS
BECOME BREEZY THIS AFTERNOON AS THE GRADIENT INCREASES AS PRESSURE
BEGIN TO LOWER OVER WESTERN TEXAS AND NE MEXICO IN RESPONSE TO AN
APPROACHING UPPER TROUGH.

TONIGHT...THE MID LEVEL TROUGH BEGINS TO MOVE INTO THE STATE BUT
MODEL PLACEMENT IS FARTHER NORTH AND TIMING OF A DISTURBANCE MOVING
ACROSS SOUTH CENTRAL TEXAS AFTER MIDNIGHT TONIGHT/FRIDAY MORNING
SUGGEST ANY THUNDERSTORMS OR MCS THAT DEVELOPS ARE LIKELY TO TRACK
JUST NORTH OF THE CWA. MODEL GUIDANCE ALSO CONTINUES VERY LOW POPS
FOR MOST AREAS WITH 20-30 PERCENT JUST ALONG THE NORTHERN RANCHLANDS
WHICH LOOKS RIGHT ON TRACK WITH CURRENT THINKING. WITH THAT SAID
SPC CONTINUES TO INDICATE A BROAD BRUSHED MARGINAL RISK AREA THAT
COVERS MUCH OF THE CWA. THIS MIGHT BE A BIT OVER PLAYED AS THE
SOUTHERN EXTENT OF THE DISTURBANCE TRAVERSES INTO A WEAK CAPPED AND
LOW SHEAR ENVIRONMENT. ANY STORMS OR MCS THAT DO FORM ARE LIKELY TO
TRACK JUST NORTH OR ALONG THE NORTHERN CWA BORDER OVER THE
RANCHLANDS. DEVELOPING SOUTHEAST LOW LEVEL JET 25-35 KNOTS COULD
SUSTAIN ANY THUNDERSTORMS WELL PASS MIDNIGHT WHICH IS IN GOOD
AGREEMENT WITH THE FORECAST AND MODEL OUTPUT.

FRIDAY...MID LEVEL TROUGH AXIS TO LIE OVER CENTRAL TEXAS AND ANY
ONGOING THUNDERSTORMS ARE LIKELY TO BE OVER THE NORTHERN RANCHLANDS
MAYBE EXTENDING INTO NORTHERN HIDALGO IN THE MORNING. ANY LEFT OVER
CAP CONTINUES TO WEAKEN AS 850-700MB COOLS SLIGHTLY. THIS MIGHT BE
SUFFICIENT FOR ADDITIONAL SHOWERS AND THUNDERSTORMS TO DEVELOP WITH
THE DAYTIME HEATING BUT CONFIDENCE IS LOW ON INCREASING POPS TO WILL
BE MAINTAINING LOW POPS WITH MOISTURE DEPTH AND VALUES MUCH LOWER
THEN THE LAST SEVERAL WEEKS. PWATS REMAIN BETWEEN 1.5 AND 1.7 INCHES
AND UPPER SUPPORT WILL BE TRACKING EASTWARD WITH MUCH BETTER
DIVERGENCE PASSING TO OUR NORTHEAST. MODELS OUTPUT REMAINS
CONSISTENT KEEPING POPS AT OR BELOW 30 PERCENT WITH THE HIGHEST POPS
ACROSS THE NORTH. ANOTHER MARGINAL RISK IS INDICATED FOR MUCH OF THE
CWA BUT THIS SEEMS OVER DONE AS WELL BUT CAN NOT RULE OUT A ROUGE
STORM WITH CAPE VALUES IN THE 2500 J/KG RANGE AND THE DECAYING
CAP.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...MID LEVEL PATTERN
WILL BE CHARACTERIZED BY TROUGH ACROSS THE EASTERN HALF OF THE
CONUS WITH A DEVELOPING CLOSED LOW ACROSS THE OZARKS AND SLOWLY
RETROGRADING SOUTHWESTWARD. THIS WILL SUPPORT THE TAIL END OF A
SOUTHWARD MOVING COLD FRONT INTO SOUTH TEXAS SUNDAY AND
MONDAY...EVENTUALLY DISSIPATING BY TUESDAY. RIDGING WILL DEVELOP
ACROSS THE WESTERN HALF OF THE CONUS THIS WEEKEND BEING UNDERCUT
BY A PROGGED TROPICAL CYCLONE ACROSS THE EASTERN PACIFIC AND A
SHORTWAVE TROUGH OVERTOPPING AND BREAKING DOWN THE RIDGE EARLY
NEXT WEEK.

MOISTURE WILL POOL IN THE LOW LEVELS SOUTH OF THE BOUNDARY BUT PWATS
ARE NOT OVERLY HIGH. WILL KEEP CHANCE POPS GOING SATURDAY ACROSS THE
INLAND AREAS. AS THE FRONT GETS CLOSER OUR LOW LEVEL WINDS BECOME
EASTERLY AND WEAK...A GOOD SETUP FOR SEABREEZE SHOWERS AND
THUNDERSTORMS BOTH SUNDAY AND MONDAY. HOWEVER...AM RELUCTANT TO GO
ANY HIGHER ON POPS DUE TO PWATS OF 1.5 SUNDAY AND 1.3 MONDAY.
THEREFORE WILL KEEP POPS AS IS AND COULD LOWER FOR MONDAY WITH
SUBSEQUENT SHIFTS. DRIER AIR CONTINUES MOVING IN TUESDAY AND
WEDNESDAY SO NO MORE THAN A SLIGHT CHANCE MENTION IS WARRANTED AT
THIS TIME.

WITH INCREASED CLOUDS A CHANCES FOR PRECIPITATION SATURDAY THROUGH
MONDAY KEPT TEMPERATURES CLOSER TO SUPERBLEND GUIDANCE WHICH IS
SLIGHTLY LOWER THAN MEX GUIDANCE AND CLIMO. WITH DRIER AIR AND LESS
CLOUD TUESDAY AND WEDNESDAY NUDGED TEMPERATURES TOWARDS MEX GUIDANCE
WHICH IS SLIGHTLY ABOVE CLIMO.

MARINE /NOW THROUGH FRIDAY/...PRESSURES LOWER OVER THE SOUTHERN
AND CENTRAL PLAINS THE NEXT 24-36 HOURS AS MID LEVEL LOW PRESSURE
TROUGH MOVES INTO TEXAS. THE LOWER PRESSURE TO COMBINE WITH THE
BROAD HIGH PRESSURE ACROSS THE GULF PROVIDE A MODERATE TO
MODERATELY STRONG PRESSURE GRADIENT. WINDS INCREASE ACROSS THE
LAGUNA DURING THE LATE MORNING AND AFTERNOON WITH EXERCISE CAUTION
CONDITIONS DEVELOPING. THE MODERATE FETCH TO MAINTAIN MARGINAL
SMALL CRAFT CONDITION SEAS TODAY AND FRIDAY

FRIDAY NIGHT THROUGH MONDAY...GENERALLY HIGH PRESSURE WILL STRETCH
ACROSS THE GULF OF MEXICO INCLUDING THE LOWER TEXAS COASTAL
WATERS. A COLD FRONT WILL MOVE SOUTHWARD INTO SOUTH TEXAS SUNDAY
AND MONDAY. SOUTHEASTERLY WINDS SATURDAY WILL GIVE WAY TO
DECREASING EASTERLY WINDS SUNDAY AND MONDAY. AS WIND DECREASE SO
WILL THE SEA HEIGHTS FROM 3-5 FEET SATURDAY TO NEAR 2 FEET BY
MONDAY. FAVORABLE MARINE CONDITIONS EXPECTED THIS PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  88  79  89  79 /  20  10  10  10
BROWNSVILLE          90  79  90  77 /  20  10  10  10
HARLINGEN            91  78  92  75 /  20  10  10  10
MCALLEN              93  78  94  76 /  10  10  10  10
RIO GRANDE CITY      93  76  93  76 /  10  20  10  10
SOUTH PADRE ISLAND   85  80  85  80 /  20  10  10  10

&&

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

$$

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