Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 312331 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
631 PM CDT TUE MAR 31 2015

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

&&

.AVIATION...BREEZY CONDITIONS WILL CONTINUE THROUGH THE EVENING
BEFORE LOWERING TO AROUND 10 KNOTS AS MIXING ENDS. HIGH CIRRUS
WILL CONTINUE THROUGH THE NIGHT...WITH LOW CLOUDS DEVELOPING BY
MIDNIGHT AREAWIDE. CIGS STILL EXPECTED TO FALL TO AROUND 1500.
HAZY AND FOGGY CONDITIONS WILL DEVELOP AGAIN LATE DUE TO MOISTURE
TRAPPED ALONG THE SFC AND SMOKE FROM FIRES TO THE SOUTH. CLOUDY
CONDITIONS WILL CONTINUE TOMORROW...WITH CIGS RISING BY LATE
MORNING. WINDY CONDITIONS ARE AGAIN EXPECTED TOMORROW...WITH WINDS
SUSTAINED 15 TO 20 KNOTS WITH GUSTS OF 25 TO 30KTS.

&&

.PREV DISCUSSION... /ISSUED 238 PM CDT TUE MAR 31 2015/

SHORT TERM.../NOW THROUGH WEDNESDAY NIGHT/...THE MAIN CHALLENGE
WILL BE THE MID LEVEL LOW MOVING ASHORE IN NORTHWEST MEXICO. THE
DISTURBANCE WILL PICK UP SPEED AND MOVE AT A GOOD CLIP ALONG THE
NORTHERN EDGE OF A SUBTROPICAL JET STREAK TONIGHT. IT WILL MOVE
ACROSS NORTHERN MEXICO TONIGHT AND WILL THEN OPEN UP AS IT MOVES
OVER TEXAS WEDNESDAY...EXITING TO THE EAST WEDNESDAY NIGHT. THERE IS
CURRENTLY A MIX OF LOW AND HIGH CLOUDS...FROM STRONG SOUTHEASTERLY
LOW LEVEL INFLOW AND THE PACIFIC MOISTURE MOVING OVER ALOFT. TEMPS
ARE MAINLY IN THE UPPER 70S TO LOWER 80S ACROSS THE CWA.

TONIGHT...NO REAL EXCITEMENT FOR THE AREA EARLY TONIGHT AS THE
DISTURBANCE WILL STILL WELL TO THE WEST. OVERNIGHT LOW TEMPERATURES
WILL BE IN MID TO UPPER 60S OR LOWER 70S...WITH A LIGHT TO MODERATE
SOUTHEAST WINDS BRINGING MOISTURE IN FROM THE GULF. A FEW SHOWERS OR
THUNDERSTORMS MAY DEVELOP OVER THE FRONT RANGE OF THE SIERRA MADRES
AFTER MIDNIGHT...AND COULD APPROACH THE UPPER VALLEY LATE. MENTIONED
A SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS FOR THE UPPER VALLEY FOR
THIS PERIOD.

WEDNESDAY...BEST RAIN CHANCES WILL BE WEDNESDAY AS THE TROUGH SHEARS
OUT OVER THE BIG BEND AND CENTRAL TEXAS. THE SCENARIO MAY EVOLVE AS
INCREASING CONVECTION DEVELOPING TO THE WEST TONIGHT MOVES INTO THE
CWA WEDNESDAY MORNING. BKN TO OVC LOW CLOUDS MAY HELP COUNTERACT THE
EFFECTS OF STRONGER DAYTIME HEATING...WITH HIGH TEMPS RUNNING FROM
THE MID AND UPPER 70S EAST TO THE MID 80S WEST. MAINTAINED POPS IN
THE 30 TO 40 PERCENT RANGE. THE FORECAST SOUNDING DOES NOT LOOK
TERRIBLY UNSTABLE BUT THERE IS NO CAP EITHER. THUS...GENERAL GARDEN
VARIETY TSTMS MAY DEVELOP. MODERATE TO BREEZY SOUTHEAST WINDS WILL
CONTINUE.

WEDNESDAY NIGHT...AS THE TROUGH SLIDES EAST CONDITIONS WILL SETTLE
DOWN AND THERE WILL BE SLIGHT CLEARING FROM WEST TO EAST. LOW TEMPS
WILL AGAIN RANGE FROM THE MID 60S ACROSS THE RANCHLANDS TO THE LOWER
70S AT THE COAST. LIGHT SOUTHEAST WINDS WILL PREVAIL UNDER PARTLY TO
MOSTLY CLOUDY SKIES.

LONG TERM /THURSDAY THROUGH TUESDAY/...GENERAL ZONAL PATTERN
ACROSS THE SOUTHERN U.S. WITH LOW PRESSURE TROUGHS ANCHORED ALONG
BOTH COASTS AND BROAD SUBTROPICAL HIGH PRESSURE OVER NORTHERN
MEXICO AND SOUTH TEXAS. A TYPICAL WARM AND BREEZY SPRING PATTERN
BRIEFLY INTERRUPTED BY A RATHER MODERATELY STRONG COLD FRONT
SATURDAY.

MUCH OF IMPETUS WILL BE FOCUSED ON A STRONG SHORTWAVE TRAVERSING
THE CENTRAL US THURSDAY INTO FRIDAY BUT MOVING INTO A CONFLUENT
FLOW WEAKENING AS IT MOVES EAST OF THE CENTRAL PLAINS. THIS SHOULD
WEAKEN THE FORCING ALONG A COLD FRONT AS IT MOVES INTO SOUTH TEXAS
FRIDAY AND OFF THE LOWER TEXAS COAST FRIDAY NIGHT INTO EARLY
SATURDAY. COASTAL TROUGH SETS UP SATURDAY AS A WEAK IMPULSE MOVES
INTO WEST TEXAS. THIS WILL SET THE STAGE FOR A COOL OVERRUNNING
PATTERN FOR AT LEAST THE FIRST HALF OF THE UPCOMING WEEKEND. THE
MAIN QUESTION WITH THIS FRONT WILL BE THUNDERSTORM ACTIVITY AND
HOW WIDESPREAD OR ISOLATED THEY WILL BE. STRONG CAP DEVELOPS IN
ADVANCE OF THE FRONT WITH WARM SOUTHWEST FLOW BETWEEN 925-700MB
CAP. THE CAP WEAKENS AS THE FRONT MOVES THROUGH THE REGION AFTER
MIDNIGHT FRIDAY NIGHT HOWEVER LARGE SCALE ASCENT IS LIMITED WITH
SUBTROPICAL HIGH PRESSURE NOSING INTO OUR REGION AND WEAK JET
DYNAMICS REMAINING WELL NORTH OF THE REGION. BETTER ELEVATED
INSTABILITY EXIST OVER THE NORTHERN RANCHLANDS WITH THE CAP
HOLDING ON ALONG WITH ONSET OF COOLER OVERNIGHT TEMPERATURES
LIMITING THE INSTABILITY KEEPING THE THUNDERSTORM CHANCES TO
ISOLATED AT BEST ACROSS THE RIO GRANDE VALLEY. WITH THIS SAID
HAVE BACKED OFF ON THE THUNDERSTORM CHANCES BUT KEPT THE
RAIN/DRIZZLE /LOW QPF/ IN THE GOOD CHANCE TO LIKELY RANGE.
TEMPERATURES WILL BE TRICKY WITH UNCERTAINTY ON HOW COOL THE
AIRMASS WILL BE. 12Z GFS MODEL GUIDANCE HAS COME IN LOWER WITH
NEAR 60 NORTH AND UPPER 60S SOUTH. CLIMATE RECORDS INDICATE SOME
EARLY APRIL COLD FRONTS HAVE LOWERED TEMPERATURES INTO THE LOWER
50S TO LOWER 60 DEGREES IN THE VALLEY. DO NOT ANTICIPATED THIS
TYPE OF COOL AIR BUT WITH THE OVERRUNNING AND A THICK LOW CLOUD
DECK AND PERIODIC RAIN MODEL GUIDANCE MIGHT BE ON TO SOMETHING
LOWERING TEMPERATURES THE LAST FEW RUNS. WILL TREND IN THIS
DIRECTION BY LOWERING FORECAST LOW FRIDAY NIGHT AND THE HIGHS ON
SATURDAY. RECOVERY IS SHOWN BY BOTH GFS AND ECMWF AS SOUTH WINDS
RETURNING RATHER QUICKLY AS PRESSURES LOWER ACROSS THE LEE SIDE OF
THE ROCKIES AND SOUTHERN PLAINS WITH THE RETREAT OF A WARM FRONT.
SOME RAIN MAY LINGER SUNDAY MORNING SPREADING/ENDING SOUTH TO
NORTH. MID LEVEL SOUTHWEST FLOW RESUMES EARLY NEXT WEEK WITH
TEMPERATURES ON THE RISE AS WILL THE SPRING TIME WINDS.

MARINE...NOW THROUGH WEDNESDAY NIGHT...MDT SEAS 3 TO 5 FEET IN
THE SHORT TERM...WITH MODERATE SOUTHEAST WINDS AS WELL...THOUGH
A LITTLE STRONGER TONIGHT OVER THE GULF...WITH EXERCISE CAUTION
CONDITIONS. A FEW SHOWERS AND THUNDERSTORMS MAY DEVELOP WEDNESDAY
AS A MID LEVEL DISTURBANCE ARRIVES FROM THE WEST AND MOVES OVER
THE AREA. A TIGHTER GRADIENT OVER THE GULF WILL RESULT IN AN
INCREASE OF THE SWELL COMPONENT AND SEAS MAY BUILD TO 6 FEET
OFFSHORE WEDNESDAY NIGHT.

THURSDAY THROUGH SUNDAY/...MODERATE SOUTHEASTERLY FLOW TO BE
BRIEFLY INTERRUPTED FRIDAY NIGHT THROUGH SATURDAY AS A LATE SEASON
COLD FRONT PUSHES THROUGH THE LOWER TEXAS COASTAL WATERS. THE
MODERATE COLD FRONT SHOULD BRING ABOUT A SHORT PERIOD OF SMALL CRAFT
ADVISORY CONDITIONS SATURDAY MORNING. NORTHEAST WINDS TAPER OFF
LATER SATURDAY AS A COASTAL TROUGH DEVELOPS. WINDS RETURN TO THE
SOUTH SUNDAY BUT COULD BECOME GUSTY LATER IN THE DAY AS THE PRESSURE
GRADIENT STRENGTHENS WITH LOW PRESSURE DEVELOPING OVER THE SOUTHERN
PLAINS. EXERCISE CAUTION LEVELS LOOK MORE LIKELY THAN FULL FLEDGED
ADVISORY CONDITIONS.

&&

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

$$

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