000
FXUS64 KBRO 041153 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
553 AM CST WED MAR 4 2015

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

&&

.AVIATION...IR SATL IMAGERY SHOWS A FAIRLY RAGGED DECK OF LOW CLDS
IN PLACE OVER DEEP SOUTH TX THIS MORNING DUE TO THE STRONG AND
STEADY SOUTHERLY LOW LEVEL FLOW PERSISTING OVER THE REGION AHEAD
OF THE NEXT COLD FRONT APPROACHING THE REGION LATER TONIGHT. THE
CEILINGS MAY IMPROVE SOME LATER TODAY AS THE DAY TIME HEATING
INCREASES POSSIBLY RESULTING IN SOME MVFR/VFR CONDITIONS. AFTER
SUNSET THIS EVENING THE CEILINGS WILL LIKELY LOWER ONCE AGAIN AS A
FAIRLY MOIST NOCTURNAL INVERSION REFORMS RESULTING IN IFR/LIFR
CONDITIONS THIS EVENING AND TONIGHT. ALSO AS THE SURFACE WINDS
SLACKEN AHEAD OF THE NEXT COLD FRONT THE POTENTIAL FOR FOG WILL
INCREASE POSSIBLY REDUCING VSBYS DOWN INTO THE 2 TO 4 MILE RANGE
LATE TONIGHT. THE COLD FRONT WILL PUSH THROUGH THE RGV AIRPORTS
TOWARDS THE END OF THE 12Z TAF ISSUANCE RESULTING IN STRONGER
NORTHERLY SURFACE WINDS.

&&

.PREV DISCUSSION... /ISSUED 433 AM CST WED MAR 4 2015/

SHORT TERM /NOW THROUGH THURSDAY/...THE BROAD AND ELONGATED 500 MB
TROUGH AXIS SPRAWLING ACROSS THE MUCH OF THE NORTHERN AND WESTERN
STATES WILL PUSH STEADILY EAST THROUGH THE SHORT TERM PERIOD. THIS
WILL USHER THROUGH A PRETTY SIGNIFICANT COLD FRONT THROUGH THE AREA
LATE TONIGHT THROUGH EARLY THURSDAY MORNING. AHEAD OF THIS FRONT WAA
WILL PREVAIL TODAY DUE TO THE PERSISTENT S-SE LOW LEVEL FLOW AHEAD
OF THE FRONT. THIS WILL DRIVE THE AFTERNOON HIGHS ON INTO THE 80S.
WILL LEAN CLOSER TO THE SLIGHTLY WARMER MAV AND ECMWF GUIDANCE FOR
HIGHS TODAY. NAM MUCAPE VALUES AROUND THE TIME OF THE FROPA INCREASE
INTO THE 1000 TO 1300 J/KG RANGE AROUND 06Z TONIGHT. THESE VALUES
THEN DIMINISH PRETTY QUICKLY AS THE CAA INCREASES TOWARDS 12Z THURS.
SO WILL MAINTAIN A MENTION OF TRW THROUGH THE OVERNIGHT HOURS. THE
PCPN SHOULD THEN CONVERT OVER QUICKLY TO RW/R DURING THE DAY THURS
AS THE CAA STABILIZES THE ATMS.

THE SHORT TERM MODELS DIFFER QUITE A BIT ON THE DEGREE OF CAA MOVING
IN BEHIND THE FRONT ON THURS WITH THE MAV AND ECMWF COMING IN WARMER
THAN THE MET TEMP GUIDANCE. WILL GO WITH THE COOLER MET NUMBERS FOR
TEMPS THURS AS THE MET NUMBERS HAVE APPARENTLY BEEN DOING BETTER IN
HANDLING THE CAA EVENTS LATELY.

THE COMBINATION OF THE INCREASING CAA AND THE STRONG NORTH WINDS
WILL ALLOW THE WIND CHILL VALUES TO FALL DRAMATICALLY IN THE WAKE OF
THE FROPA POSSIBLE REACHING WIND CHILL ADVISORY LEVELS DURING THE
DAY THURS. ALSO SUSTAINED WIND SPEEDS AFTER THE FRONT COULD REACH
WIND ADVISORY CRITERIA ESPECIALLY ACROSS THE COASTAL COUNTIES OF
KENEDY...WILLACY AND CAMERON ON THURS. FOR NOW WILL HOLD OFF ON
POSTING THESE ADVISORIES AT THIS TIME TO SEE HOW THIS EVENT SHAPES
UP LATER TONIGHT INTO THURSDAY.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...ARCTIC SOURCE AIRMASS
WILL SETTLE OVER DEEP SOUTH TEXAS THURSDAY NIGHT THROUGH SATURDAY.
CAA WILL CONTINUE ACROSS THE AREA THURSDAY NIGHT INTO SATURDAY. LOW
TEMPERATURES THURSDAY NIGHT WILL BE IN THE 30S...WITH WIND CHILLS IN
THE UPPER 20S TO AROUND 30 DEGREES AS BRISK NORTH WINDS CONTINUE
ACROSS THE AREA. A WIND CHILL ADVISORY WILL BE POSSIBLE ACROSS
PORTIONS OF DEEP SOUTH TEXAS THURSDAY NIGHT INTO FRIDAY MORNING.
SOUTHWEST WINDS ALOFT WILL ALLOW OVERRUNNING CONDITIONS...PERSISTENT
CLOUDY SKIES WITH PATCHY DRIZZLE AND LIGHT RAIN...THURSDAY NIGHT
INTO SATURDAY MORNING. TEMPERATURES WILL REMAIN WELL BELOW NORMAL
THROUGH THE WEEKEND. HIGH TEMPERATURES FRIDAY WILL REMAIN GENERALLY
IN THE 40S UNDER CLOUDY SKIES WITH LIGHT RAIN AND
DRIZZLE...ESPECIALLY NEAR THE COAST. LOW TEMPERATURES FRIDAY NIGHT
WILL FALL INTO THE 30S ACROSS THE RANCHLANDS TO THE LOWER 40S NEAR
THE COAST. NO FREEZING TEMPERATURES EXPECTED AT THIS TIME ACROSS
DEEP SOUTH TEXAS.

THE DEVELOPMENT OF A COASTAL TROUGH OFF THE LOWER TEXAS COAST ALONG
WITH AN APPROACHING A 500MB TROUGH...WILL PROVIDE A CHANCE OF RAIN
SATURDAY AND SUNDAY. RAIN CHANCES WILL LINGER INTO EARLY NEXT WEEK
AS THIS SYSTEM WILL BE SLOW TO MOVE EASTWARD. A SLOW RECOVERY IN
TEMPERATURES CAN BE EXPECTED LATE IN THE WEEKEND INTO EARLY NEXT
WEEK.

MARINE /NOW THROUGH THURSDAY/...THE FIRST ITEM ON THE AGENDA FOR
THE MARINE AREAS TODAY WILL BE THE FOG POTENTIAL. WAA IS OCCURRING
DUE TO THE SOUTHERLY WINDS MOVING OVER THE LOWER TEXAS GULF
WATERS. THIS WAA IS SPREADING OVER FAIRLY COOL BAY AND SURF WATER
TEMPS IN THE UPPER 50S RESULTING IN AREAS OF DENSER MARINE FOG
NEAR PADRE ISLAND. WILL ISSUE A MARINE DENSE FOG ADVISORY FOR THE
BAY WATERS AND EXTENDING OFFSHORE TO 20 NM THROUGH MIDDAY TODAY.

EXPECT THE PGF TO STRENGTHEN DRASTICALLY JUST AFTER THE FRONT
PUSHING THROUGH THE LOWER TX MARINE WATERS BETWEEN 06 AND 12Z THURS.
THIS WILL PUSH THE MARINE CONDITIONS ACROSS THE BAY AND GULF WATERS
TO NEAR GALE FORCE LEVELS PRETTY QUICKLY ON THURS. ACCORDINGLY WILL
BE UPDGRADING THE GALE WATCH TO A GALE WARNING FOR ALL OF THE LOWER
TX MARINE AREAS FROM 06Z THURS THROUGH 00Z FRI.

THURSDAY NIGHT THROUGH SUNDAY...ADVERSE MARINE CONDITIONS WILL
CONTINUE ACROSS THE LOWER TEXAS COASTAL WATERS THURSDAY NIGHT INTO
FRIDAY DUE TO STRONG NORTH WINDS AND HAZARDOUS SEAS. MARINE
CONDITIONS GRADUALLY IMPROVE FRIDAY NIGHT THROUGH THE WEEKEND AS THE
PRESSURE GRADIENT WEAKENS. MODERATE NORTH TO NORTHEAST WINDS WILL
CONTINUE SATURDAY INTO SUNDAY. SMALL CRAFT ADVISORY CONDITIONS MAY
LINGER ACROSS THE GULF WATERS THROUGH THE LATTER PORTIONS OF THE
WEEKEND DUE TO ELEVATED SEAS.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  80  42  44  39 /  10  50  60  40
BROWNSVILLE          84  39  42  37 /  10  50  60  40
HARLINGEN            85  39  42  37 /  10  60  60  40
MCALLEN              87  38  40  36 /  10  60  50  30
RIO GRANDE CITY      88  40  41  35 /  10  60  40  10
SOUTH PADRE ISLAND   75  45  46  42 /  10  50  60  40

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR GMZ130-132-135-150-
     155.

     GALE WARNING FROM MIDNIGHT TONIGHT TO 6 PM CST THURSDAY FOR
     GMZ130-132-135-150-155-170-175.

&&

$$

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

SHORT TERM...60
LONG TERM...63
GRAPHICAST/UPPER AIR...67