000
FXUS64 KBRO 270520 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1120 PM CST THU FEB 26 2015

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

&&

.AVIATION...SOME CLOUDINESS AROUND 3K FEET HAS MOVED OVER THE
BRO/HRL AERODROMES WITH CLEAR SKIES OVER MFE. A COLD FRONT
CONTINUES TO MOVE THROUGH SOUTH TEXAS...AND SHOULD PASS THROUGH
THE THREE MAJOR AERODROMES OF DEEP SOUTH TEXAS AND THE RIO GRANDE
VALLEY AROUND SUNRISE FRIDAY MORNING. VERY LIGHT PRECIPITATION
WITH REDUCED VISIBILITIES AND MUCH LOWER CEILINGS WILL DEVELOP AND
PREVAIL IN THE WAKE OF THE COLD FRONT TOMORROW.

&&

.PREV DISCUSSION... /ISSUED 547 PM CST THU FEB 26 2015/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...A COLD FRONT IS GRADUALLY PROGRESSING THROUGH CENTRAL
TEXAS AND SHOULD PASS THROUGH THE RIO GRANDE VALLEY AND DEEP SOUTH
TEXAS AROUND SUNRISE FRIDAY MORNING. VFR CONDITIONS ARE EXPECTED
TO PREVAIL UNTIL THAT TIME. AFTER THE FRONTAL PASSAGE...VERY LIGHT
PRECIPITATION WITH REDUCED VISIBILITIES AND LOWERING CEILINGS ARE
LIKELY.

PREV DISCUSSION... /ISSUED 239 PM CST THU FEB 26 2015/

SHORT TERM /NOW THROUGH FRIDAY NIGHT/...CURRENTLY FRONT IS LOCATED
OVER NORTH CENTRAL TEXAS HEADING SOUTH WITH HIGH PRESSURE GRADUALLY
BUILDING ACROSS THE COASTAL WATERS. SATELLITE IMAGERY AND
OBSERVATIONS SHOWS A PREDOMINANT EASTERLY WIND WEST OF HWY 83 WHILE
TOWARDS THE EAST THE NORTHEAST FLOW IS STARTING TO SET UP. THIS
FRONT WILL MAKE ITS WAY ACROSS DEEP SOUTH TEXAS WITH COLDER AIR MASS
MAINLY WESTWARD  HUGGING THE SIERRA MADRE. THE CLOUD COVER WILL
BEGIN TO INCREASE ACROSS THE AREA STARTING TONIGHT WITH TEMPERATURES
TRENDING LOWER. MOST LOCATIONS WEST OF HWY 77 AND 281 WILL
EXPERIENCE TEMPERATURES IN THE LOW 40S WHILE EAST OF HWY 77
TEMPERATURES WILL BE NEAR 50. ISENTROPIC LIFT WILL BEGIN TO SET UP
LATE TONIGHT INTO EARLY FRIDAY ALLOWING FOR LIGHT RAIN AND DRIZZLE
TO DEVELOP AND INCREASE BY THE EARLY MORNING HOURS FRIDAY. THIS
PATTERN WILL PREVAIL THROUGH THE DAY WITH A FEW BREAKS IN
BETWEEN...BUT THE COMBINATION OF THIS RAIN AND COLD TEMPERATURES
WILL MAKE IT FEEL UNCOMFORTABLE TO THOSE THAT ARE WORKING OUTSIDE.
THE CLOUD DECK WILL LOWER AND REMAIN AROUND 2 KFT TO 5 KFT KEEPING
THE COLD AND GREY DAY FRIDAY. THERE WILL BE A SHARP TEMP GRADIENT
SET UP ACROSS THE CWA AS A MORE EASTERLY FLOW DEVELOPS ALONG THE
COAST AND LOWER VALLEY WHILE WEST OF HWY 77 THE TEMPERATURES WILL
REMAIN COLDER IN THE MID TO LOW 40S THROUGH OUT THE DAY. HIGHS
TOWARDS THE COAST WILL REACH THE MID 60S. POTENTIAL FOR RAIN WILL
INCREASE INTO LATE FRIDAY INTO SATURDAY AS THE 295-300K ISENTROPIC
LIFT AND LOW CONDENSATION PRESSURE DEFICITS LEADS TO INCREASED
CHANCES FOR LIGHT RAIN ACROSS MUCH OF DEEP SOUTH TEXAS FRIDAY.
SLIGHT CHANCE TO CHANCE POPS LOOK REASONABLE WITH AMOUNTS ON THE
LIGHT SIDE. ABUNDANT CLOUD COVER WILL HOLD TEMPERATURES IN THE 40S
AND 50S.

LONG TERM /SATURDAY THROUGH THURSDAY/...OVERRUNNING CONDITIONS
ACROSS DEEP SOUTH TEXAS SATURDAY WILL MOVE NORTHWARD SUNDAY AS THE
COLD AIR ACROSS THE CWA LIFTS NORTHWARD AHEAD OF A WARM FRONT.
WARM AIR ADVECTION WILL CONTINUE SUNDAY INTO MONDAY EVEN AS HIGH
PRESSURE BUILDS INTO THE MIDWEST UNITED STATES IN THE WAKE OF THE
COLD AIR ENTRENCHED ACROSS THE EASTERN U.S. SATURDAY MOVING
EASTWARD. A 500MB LOW DEVELOPS ACROSS THE WEST U.S. COAST
SATURDAY INTO SUNDAY BEFORE EVOLVING INTO A LONGWAVE TROUGH ACROSS
THE WESTERN U.S. MONDAY INTO TUESDAY. SURFACE LOW PRESSURE WILL
DEVELOP ACROSS THE SOUTHERN ROCKIES AND MOVE INTO THE CENTRAL
PLAINS MONDAY INTO TUESDAY. THE GLOBAL MODELS DIVERGE AFTER
TUESDAY WITH THE GFS PROGGING A FRONTAL WAVE DEVELOPING ACROSS
SOUTH TX WEDNESDAY AND THE ECMWF BRINGING A COLD FRONT THROUGH
CENTRAL TX. HOWEVER...THEY ARE IN AGREEMENT WITH BRINGING ANOTHER
SURGE OF COLD AIR THROUGH THE RIO GRANDE VALLEY BY THE END OF THE
FORECAST PERIOD. WILL GO WITH A BLEND OF THE CONSENSUS MODELS AND
THE GFS FOR WEDNESDAY AND THURSDAY FOR NOW.

MARINE...
NOW THROUGH FRIDAY NIGHT...THE NORTHEAST WINDS HAVE STARTED TO
PICK UP WITH GUSTS UP TO 22 KNOTS AT THE BOUY 2020. AS THE COLD
FRONT MAKES ITS WAY ACROSS THE AREA...THE NORTHEAST FLOW WILL
CONTINUE TO INCREASE WITH SCA OVER THE GULF IN EFFECT THROUGH THE
NIGHT AND INTO EARLY FRIDAY. THE WINDS WILL SHIFT EAST AND LOWER
EARLY IN THE MORNING HOURS BUT WITH THE PRESSURE GRADIENT
STRENGTHENING ONCE AGAIN EXPECT EAST WINDS TO INCREASE WITH THE
POTENTIAL FOR SCA STARTING FRIDAY AFTERNOON INTO SATURDAY. SEAS
WILL BUILD AS A RESULT OF THE LONG EASTERLY FETCH DEVELOPING
ASSOCIATED TO THE BROAD HIGH PRESSURE ACROSS THE EASTERN PORTION
OF THE CONUS.

SATURDAY THROUGH TUESDAY...MODERATE TO STRONG EAST WINDS WILL
PREVAIL ACROSS THE COASTAL WATERS SATURDAY WITH SURFACE HIGH
PRESSURE ACROSS THE EASTERN UNITED STATES. WINDS SHOULD DIMINISH
SUNDAY AS THE PRESSURE GRADIENT WEAKENS ACROSS THE WESTERN GULF OF
MEXICO AND THE SURFACE RIDGE ACROSS THE EASTERN U.S. MOVES
EASTWARD. LIGHT EAST WINDS SUNDAY WILL VEER TO THE SOUTHEAST
MONDAY AND INCREASE AS LOW PRESSURE DEVELOPS ACROSS THE SOUTHERN
ROCKIES. MODERATE SOUTHEAST WINDS MONDAY WILL VEER TO THE SOUTH
TUESDAY AND INCREASE AS LOW PRESSURE MOVES INTO THE CENTRAL PLAINS
AND DEEPENS. SMALL CRAFT ADVISORIES WILL BE NEEDED FOR THE
OFFSHORE WATERS SATURDAY AND WILL LIKELY BE NEEDED FOR THE COASTAL
WATERS TUESDAY.

&&

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

&&

$$

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

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