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000
FXUS64 KBRO 061148 AAA
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
548 AM CST FRI DEC 6 2013

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

&&

.AVIATION...PREDOMINATE IFR CONDITIONS DUE TO LOW CEILINGS
EXPECTED TODAY AS SHALLOW ARCTIC AIR REMAINS IN PLACE. AS THE
AIRMASS DEEPENS LATER TODAY CIGS RISE JUST ABOVE IFR LEVELS.
CONFIDENCE IS LOW TO MODERATE IF MVFR CONDITIONS DEVELOP AND IF
THEY DO THEY ARE EXPECTED TO LAST 4 TO 8 TO HOURS. AS AREAS OF
LIGHT RAIN AND DRIZZLE DEVELOP TONIGHT CIGS TO LOWER WITH IFR
RESUMING AND PERSISTING THROUGH SATURDAY MORNING. MODERATE NORTH WINDS
OF 10 TO 15 KNOTS WITH GUSTS TO 20 KNOTS EXPECTED MOST LOCATIONS.
COASTAL AREAS TO SEE SUSTAINED WINDS AROUND 20 KNOTS WITH GUSTS TO
25 KNOTS.

&&

.PREV DISCUSSION... /ISSUED 359 AM CST FRI DEC 6 2013/

SHORT TERM /NOW THROUGH SATURDAY/...COLD AIR TO CONTINUE TO SPILL INTO
THE VALLEY THE NEXT 24-36 HOURS. TEMPERATURES ARE LIKELY TO FALL
OR REMAIN STEADY TODAY THEN BEGIN TO FALL AGAIN TONIGHT. SATURDAY
VERY LITTLE DIURNAL RANGE TO TAKE PLACE WITH 30S TO LOW 40S CWA
WIDE. EMPHASIS IS ON WINTER WEATHER HIGHLIGHTS WITH A FREEZE
WARNING FOR THE JIM HOGG...BROOKS AND KENEDY COUNTIES WITH ZAPATA
POSSIBLY BEING ADDED TO THE MIX IN THE NEXT FORECAST UPDATE. A
WIND CHILL ADVISORY WILL COVER THE ENTIRE CWA SHORTLY AFTER
MIDNIGHT AND GO THROUGH SATURDAY MORNING WITH LITTLE LET UP IN THE
BLUSTERY NORTH WINDS. THE NEXT CONCERN WILL BE RAIN/DRIZZLE AND IF
IT MAKES IT FAR ENOUGH NORTH AND WEST. ISENTROPIC LIFT IS BEST
OVER THE COASTAL REACHES AND ACROSS THE LOWER VALLEY WHERE LIGHT
ECHOS ARE SHOWING UP ON RADAR. MODELS SUGGEST THE ISENTROPIC
UPGLIDE STRENGTHENING LATE TONIGHT INTO SATURDAY AS SOUTHERLY FLOW
INCREASES WITH THE APPROACH OF UPPER TROUGH. PRECIPITATION IS
EXPECTED TO SPREAD NORTHWEST AND THIS PUTS THE NORTHERN RANCHLANDS
ON THE FENCE IF FREEZING RAIN/DRIZZLE DEVELOPS. FORECASTER
CONFIDENCE IS LOW AT THIS TIME WITH NOT ALL MODELS IN AGREEMENT.
GFS IS THE MOST BULLISH WITH THE HIGHER POPS. NAM IS INDICATING
LOWER POPS WITH THE ECMWF TRENDING IN BETWEEN BUT MORE LEANING
WITH THE GFS. WILL CONTINUE TO MONITOR THE COLD AIR AND THE LOW
PROBABILITY OF A FREEZING RAIN ADVISORY OR WARNING FOR FREEZING
RAIN/DRIZZLE ACROSS THE NORTHERN ZONES LATE TONIGHT AND SATURDAY
MORNING.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...ISENTROPIC LIFT
WILL BE ONGOING AT THE START OF THE LONG TERM PERIOD WITH CHANCES
OF LIGHT RAIN AND DRIZZLE MAINLY ALONG AND EAST OF HWY 281. AS IT
STANDS NOW...TEMPERATURES ACROSS BROOKS AND KENEDY COUNTIES WILL
BE ABOVE FREEZING SO NO WINTRY PRECIPITATION EXPECTED. AS SURFACE
LOW PRESSURE DEVELOPS OVER THE WESTERN GULF OF MEXICO...DRIER AIR
WILL WRAP AROUND THE BACKSIDE OF THE SYSTEM WITH PRECIPITATION
CHANCES COMING TO AN END OVER THE WESTERN HALF OF THE AREA SUNDAY
AND MAYBE A FEW PEAKS OF THE SUN BEFORE DUSK. THAT LOW PRESSURE
WILL WEAKEN AS A REINFORCING SHOT OF COLDER AIR WORKS INTO THE
AREA MONDAY. THIS COLD FRONT WILL KNOCK TEMPERATURES DOWN ABOUT 10
DEGREES FROM MONDAY HIGHS IN THE MID 50S TO MID 40S ON TUESDAY.
LIGHT RAIN AND DRIZZLE RETURNS TO THE FORECAST MONDAY AND TUESDAY
FOR THE EASTERN HALF OF THE AREA. FORECAST CONFIDENCE LOWERS AFTER
TUESDAY WITH RESPECT TO A SHORTWAVE ACROSS THE SOUTHWEST CONUS AND
NORTHERN MEXICO. WILL KEEP FORECAST AS IS WEDNESDAY/THURSDAY WITH
WEAK OVERRUNNING AND DRIZZLE ACROSS THE COASTAL COUNTIES AND
COASTAL WATERS.

MARINE...NOW THROUGH SATURDAY...SMALL CRAFT ADVISORIES REMAIN
IN PLACE WITH STRONG NORTH WINDS PERSISTING THROUGH SATURDAY.
STRONG HIGH PRESSURE BUILDS INTO NORTH TEXAS SATURDAY MORNING WITH
THE PRESSURE GRADIENT PEAKING AT THAT TIME. A SLIGHT LOWERING OF
WINDS AND SEAS COULD OCCUR BY THE END OF THE FORECAST PERIOD.

SATURDAY NIGHT THROUGH TUESDAY...SMALL CRAFT ADVISORIES WILL BE
ONGOING SATURDAY NIGHT AND POSSIBLY INTO SUNDAY AS LOW PRESSURE
DEVELOPS ACROSS THE WESTERN GULF OF MEXICO AND SLOWLY MOVES
NORTHWARD AND LOW PRESSURE STRENGTHENS ACROSS THE HIGH PLAINS.
SUNDAY NIGHT WILL BE A LULL IN THE WINDS BEFORE ANOTHER COLD FRONT
SWEEPS THROUGH AND BRINGS STRONG NORTHERLY WINDS AND SMALL CRAFT
ADVISORIES WITH GALE GUSTS POSSIBLE AS WELL MONDAY NIGHT INTO
TUESDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  50  37  47  41 /  60  60  50  40
BROWNSVILLE          50  37  44  39 /  60  60  50  40
HARLINGEN            49  35  42  37 /  60  50  50  40
MCALLEN              47  36  41  37 /  30  30  40  40
RIO GRANDE CITY      46  36  42  38 /  10  20  40  30
SOUTH PADRE ISLAND   54  42  51  45 /  60  60  50  50

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...FREEZE WARNING FROM 1 AM TO 11 AM CST SATURDAY FOR TXZ249>251.

     WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 11 AM CST SATURDAY
     FOR TXZ248>257.

GM...SMALL CRAFT ADVISORY FOR WINDS UNTIL 6 AM CST SATURDAY FOR
     GMZ130-132-135.

     SMALL CRAFT ADVISORY UNTIL 6 AM CST SATURDAY FOR GMZ150-155-170-
     175.

&&

$$

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

59...AVIATION/SHORT TERM
55...LONG TERM
CAMPBELL...GRAPHICAST