Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 241758
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1158 AM CST TUE FEB 24 2015

.DISCUSSION...NORTHWEST WINDS CONTINUE AT ABOUT 10 TO 15 MPH
ADVECTING IN MUCH COLDER AIR FROM CENTRAL AND NORTHERN TEXAS. LOW
LEVEL CONVERGENCE IS ALSO INCREASING OFFSHORE AS COASTAL TROUGHING
STRENGTHENS. A THICK LAYER OF OVERCAST BLANKETS THE REGION
FURTHER HELPING TO KEEP TEMPERATURES DOWN. ADJUSTED TODAYS MAX
TEMPS AND TONIGHTS MINS DOWN A FEW DEGREES AND FIT HOURLY TEMPS
CLOSER TO THE OBSERVED CURVE. THIS PUTS US CLOSE TO WIND CHILL
ADVISORY EARLY TOMORROW AND MAY NEED TO ADD THAT LATER TODAY. FOG
IS FORMING ON THE GULF WATERS AND ADDED A DENSE FOG ADVISORY FOR
THE COMBINATION OF WIND SPEEDS DECREASING AMID COLD AIR OVER WARM
WATER...AND THEN THE ONSHORE COMPONENT ADVECTING IN HIGHER
DEWPOINTS WILL LIKELY INCREASE FOG CHANCES.

&&

.AVIATION...
IFR OR LOW MVFR CONDITIONS ARE EXPECTED THROUGH THE AFTERNOON
DETERIORATING TO IFR TONIGHT UNTIL A FRONT ARRIVES AROUND
DAYBREAK. THIS WILL DRY THE LOW LEVELS AND SLOWLY IMPROVE
VISIBILITY THROUGH THE DAY WEDNESDAY. AS WINDS SLACKEN AND BECOME
ONSHORE THROUGH TONIGHT LOWER VISIBILITIES ARE A GOOD BET WITH FOG
FORMING. THIS FOG MAY FORM A LITTLE EARLIER THAN CURRENTLY
INDICATED IN THE TAFS...ESPECIALLY AS YOU GET CLOSER TO THE COAST.
ANY VISBY RESTRICTIONS SHOULD IMPROVE QUICKLY HOWEVER ONCE THE
WINDS SHIFT NORTHWESTERLY. /68-JGG/

&&

.MARINE...

&&

.PREV DISCUSSION... /ISSUED 532 AM CST TUE FEB 24 2015/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...LIGHT RAIN ASSOCIATED WITH WEAK OVERRUNNING IS
IMPACTING THE BRO AND HRL TERMINALS EARLY THIS MORNING WITH
TEMPORARY IFR CIGS AND MVFR VSBYS. OUTSIDE OF RAIN...CIGS WILL BE
PREDOMINATELY MVFR MOST OF THE DAY TODAY. BEST CHANCES FOR RAIN
WILL BE THIS MORNING. WINDS WILL CONTINUE FROM THE NORTH BUT WILL
VEER TO THE EAST THIS EVENING AS HIGH PRESSURE MOVES EAST AND
SURFACE LOW PRESSURE FORMS TO OUR SOUTH.

PREV DISCUSSION... /ISSUED 409 AM CST TUE FEB 24 2015/

SHORT TERM.../NOW THROUGH WEDNESDAY/...OVERRUNNING PATTERN WILL
CONTINUE TODAY ALTHOUGH IT WILL BECOME WEAK ACROSS THE WESTERN HALF
OF THE AREA AS SLIGHTLY DRIER AIR FILTERS INTO THAT AREA. FURTHER
EAST ISENTROPIC LIFT WILL HANG ON THROUGH MUCH OF THE DAY. WITH
EXPECTED CLOUD COVER AND CONTINUED NORTHERLY FLOW DID INDEED LOWER
HIGH TEMPERATURES FOR TODAY WITH UPPER 40S IN THE VALLEY AND MID 40S
IN THE RANCHLANDS. WITH DRIER AIR IN THE FAR WEST SECTIONS OF ZAPATA
COUNTY MAY REACH 50 DEGREES.

AN UPPER TROF WILL MOVE FROM THE DESERT SOUTHWEST ACROSS CENTRAL
TEXAS AND INTO THE ARKLATEX WEDNESDAY. THIS FEATURE WILL HELP
STRENGTHEN COASTAL TROUGHING AND SFC LOW PRESSURE DEVELOPING TO OUR
SOUTH AND WEST. OVERNIGHT...SFC WINDS WILL COME AROUND TO THE EAST
WHICH WILL HELP STABILIZE TEMPERATURES ESPECIALLY NEAR THE COAST
WHERE LOW TEMPERATURES WILL HOLD STEADY OR SLOWLY RISE OVERNIGHT.
PRECIPITATION CHANCES WILL RAMP BACK UP ONCE AGAIN LATE TUESDAY
NIGHT INTO EARLY WEDNESDAY WITH COASTAL TROUGHING STRENGTHENING AND
WEAK SYNOPTIC LIFT MOVING OVERHEAD. FRESH HIGH PRESSURE WILL MOVE
INTO THE AREA BEHIND THE SFC LOW PRESSURE AREA WEDNESDAY AFTERNOON
USHERING IN DRIER AIR AND A BRIEF RETURN TO NORTHERLY WINDS.

LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...IN A NUT SHELL
FORECAST CONTINUES TO BATTLE BETWEEN WINTER AND SPRING AT LEAST
HERE IN DEEP SOUTH TEXAS. WE WILL BE LOOKING AT A BRIEF SUBTLE
WARM UP THURSDAY BEFORE ANOTHER SHORT DURATION COOL DOWN FRIDAY
FOLLOWED BY A STEADY WARMING TREND NEXT WEEKEND INTO EARLY NEXT
WEEK.

MODELS IN FAIRLY GOOD AGREEMENT WITH THE BROAD LONG WAVE TROUGH
OVER NORTH AMERICA AND THE CONUS. ONE MORE SHOT OF ARCTIC AIR TO
INVADE THE NORTHERN PLAINS AND MOVE INTO THE SOUTH THROUGH MID
WEEK BEFORE THE DEEP COLD TAKES BREATHER WITH A MORE SUBSTANTIAL
TROUGH DEVELOPING ALONG THE WESTERN COAST BY BEGINNING OF MARCH.

WITH THE PASSING OF THE SOUTHERN STREAM SHORTWAVE WEDNESDAY WE CAN
EXPECT A CLEAR AND COOL WED NIGHT WITH FAIR AND MILD DAY ON
THURSDAY AS A BIT OF SUN WARMS US UP NEAR NORMAL. A SERIES OF
SHORTWAVES THEN RAPIDLY SPEED THROUGH THE ROCKIES AND ACROSS THE
CENTRAL PLAINS WITH ANOTHER SURGE OF HIGH PRESSURE NOSING INTO
TEXAS. GFS IS FARTHER SOUTH AND COLDER WITH THIS SYSTEM THEN THE
EC AT THIS TIME AND WILL TREND ON THE COOLER SIDE OF GUIDANCE AS
THE COLDER AIR BEGINS TO FILTER INTO THE CWA THU NIGHT. ANOTHER
OVERRUNNING SCENARIO DEVELOPS FRIDAY AS A SHEAR AXIS MOVES ACROSS
TEXAS. SOUTHERLY 850MB WINDS STRENGTHEN AND MOISTURE DEEPENS AS
THE COLDER AIR BECOME DAMNED UP AGAINST THE SIERRA MADRE. RAIN
CHANCES INCREASE AS THE ISENTROPIC LIFT STRENGTHENS IN RESPONSE
TO THE DEVELOPING WESTERN TROUGH.

AS THE WESTERN TROUGH DEEPENS NEXT SATURDAY AND THE MIDWEST SURFACE
HIGH SHIFTS TO THE EAST WARMER AIR TO ENSUE. RAIN CHANCES CONTINUE
INTO EARLY SATURDAY BUT CONFIDENCE REMAINS LOW WITH MORE CLOUDS
ANTICIPATED PROBABLY SOMETHING MORE LIKE THIS PASS WEEKEND. THE
WARMING TREND CONTINUES SUNDAY AND INTO NEXT WEEK AS THE SOUTHERLY
FLOW INCREASES EVEN MORE. A STRONGER S-SW FLOW ALOFT TO ALLOW FOR
SOME DRIER AIR AND THE INEVITABLE WIND TO MIX TO THE SURFACE
GIVING US MORE SUN TO WARM US UP. MODEL GUIDANCE CONTINUES TO SHOW
THIS WARMER AND WINDIER TREND KEEPING ANY FRONTS WELL NORTH OF
DEEP SOUTH TEXAS UNTIL AT LEAST THE MIDDLE OF NEXT WEEK.

MARINE...NOW THROUGH WEDNESDAY...SMALL CRAFT ADVISORIES OVER THE
GULF WATERS ARE SET TO EXPIRE AT 4AM LOCAL TIME AND BUOY 42020
SUPPORTS LETTING THE SCA EXPIRE WITH SUSTAINED WINDS 15-18 KNOTS AND
SEAS AROUND 6 FEET. THERE WILL BE A BRIEF REPRIEVE IN THE WINDS AND
SEAS TODAY AND MOST OF TONIGHT. LOW PRESSURE WILL DEVELOP TO OUR
SOUTH IN THE WESTERN GULF OF MEXICO AND AS THIS FEATURE STRENGTHENS
THE WINDS AND SEAS WILL RAMP UP ONCE AGAIN WITH SCA LIKELY
WEDNESDAY.

WEDNESDAY NIGHT THROUGH SUNDAY...MARINE CONDITIONS WILL CONTINUE
TO BE OVERALL UNSETTLED THROUGH THE LONGER TERM. HIGH PRESSURE TO
NOSE INTO THE WESTERN GULF THURSDAY GRADUALLY STRENGTHENING THE
PRESSURE GRADIENT THURSDAY INTO FRIDAY MORNING. SMALL CRAFT
ADVISORIES MAY BE NEEDED. WILL BE CONCERNED WITH A POSSIBLE
MODERATE TO STRONG LONG EASTERLY FETCH DEVELOPING OVER THE
NORTHCENTRAL GULF LATER FRIDAY INTO SUNDAY. STRONG HIGH PRESSURE TO
SPREAD OVER THE EASTERN SEA BOARD AND INTERACT WITH DEEPENING LOW
PRESSURE OVER THE ROCKY MOUNTAINS. THIS MAY PRODUCE A LONG PERIOD
SWELL TRAIN BEING DIRECTED TOWARDS THE LOWER TEXAS COAST. THE
LOCAL GRADIENT ALSO STRENGTHENS WITH SOUTHERLY FLOW STRENGTHENING
OVER THE WEEKEND. IN ANY CASE A LONG DURATION OF SMALL CRAFT
ADVISORIES MAY BE NECESSARY THROUGH THE COMING WEEKEND.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...DENSE FOG ADVISORY UNTIL 3 AM CST WEDNESDAY FOR GMZ150-155-170-
     175.

&&

$$

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