Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 191807
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1207 PM CST FRI DEC 19 2014

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

&&

.AVIATION...THE FRONT ITS MAKING ITS WAY THROUGH THE LOWER VALLEY
AS SEEING ON THE LATEST OBSERVATIONS WITH WINDS SHIFTING MORE NW
TO N WITH LOWERING TEMPS. EXPECT THE WINDS TO BECOME MORE NORTHERLY
THIS AFTERNOON AND REMAIN LIGHT THROUGH THE NIGHT. LOW CEILINGS
HAVE BEEN FLUCTUATING A BIT BUT EXPECT THIS AFTERNOON AND EVENING
TO RISE 2500 FEET. HOWEVER...AROUND MIDNIGHT CEILINGS WILL RETURN
TO LOWER MVFR THROUGH THE EARLY MORNING HOURS. INTO SATURDAY...THE
CEILINGS IMPROVE WITH NORTH WINDS GRADUALLY SHIFTING NE/E BY THE
AFTERNOON HOURS WITH VFR CONDITIONS AND CLOUD DECK BREAKING AS DRY
AIR MAKES ITS WAY INTO THE AREA.

&&

.PREV DISCUSSION... /ISSUED 910 AM CST FRI DEC 19 2014/

DISCUSSION...CHANGES WERE MADE TO POPS FOR TODAY AND THIS EVENING
AS MOST OF THE CONVECTION REMAINS CONCENTRATED TOWARDS THE COASTAL
COUNTIES EXTENDING FROM CORPUS TO HOUSTON. AS THE FRONT MAKES ITS
WAY SOUTH THIS AFTERNOON AND EVENING THE CHANCE OF ISOLATED SHOWERS
RETURNING. ACCUMULATIONS WILL BE BETWEEN A TENTH OF AN INCH OF LESS.
BETTER CHANCE STILL REMAINS OVER THE NORTHEAST COUNTIES THROUGH THE
AFTERNOON. NO ADDITIONAL CHANGES WERE MADE.

PREV DISCUSSION... /ISSUED 559 AM CST FRI DEC 19 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...A FRONTAL BOUNDARY LIES JUST NORTH OF THE CWA...WITH
AN APPROACHING MID LEVEL SHORT WAVE TROUGH OVER WEST TX PROVIDING
LIFT ALOFT AND RESULTING IN SCATTERED LGT ELEVATED SHOWERS. DRIER
AIR WILL BEGIN FILTERING IN AFTER THE MID LEVEL TROUGH MOVES EAST
OF THE AREA LATER TODAY. EVEN SO...CIGS WILL BE LIMITING BETWEEN
IFR AND MVFR MUCH OF THE DAY BECAUSE OF OVERRUNNING. SOME VSBY
REDUCTION IN MORNING FOG WILL ALSO OCCUR. LIGHT SOUTH WINDS IN THE
LWR VALLEY WILL VEER TO NORTHWEST AND THEN NORTH LATER TODAY AS
UPSTREAM HIGH PRESSURE MOVES INTO THE AREA.

PREV DISCUSSION... /ISSUED 339 AM CST FRI DEC 19 2014/

SHORT TERM /TODAY THROUGH SATURDAY/...A MID LEVEL SHORT WAVE
TROUGH WITH AXIS OVER NEW MEXICO AND WEST TEXAS IS PROVIDING SOME
LIFT OVER SOUTH CENTRAL TEXAS THIS MORNING. THE TROUGH HAS A
STALLED SURFACE BOUNDARY CUTTING ACROSS THE MIDDLE OF THE KBRO CWA
TO WORK WITH... WITH AMPLE LOW LEVEL MOISTURE BELOW 10 KFT AND DEW
POINTS IN THE 60S. THUS...UNSETTLED WEATHER IS EXPECTED THIS
MORNING AS THE TROUGH AXIS SLIPS BY OVER HEAD...AND ALREADY SEEING
RADAR RETURNS INCREASING IN COVERAGE...WITH SOME IMPROVEMENT LATER
IN THE DAY AFTER A COLD FRONT ARRIVES ON HIGH PRESS AND NORTH
WINDS. THE BEST UPPER DYNAMICS WILL LIE NORTH OF THE CWA...WITH
SCATTERED CONVECTION AND ISOLD THUNDERSTORM DEVELOPMENT LEFT TO
THE LIFT PROVIDED BY THE APPROACHING SURFACE FRONT THROUGH
AFTERNOON. MAX TEMPS WILL RANGE FROM THE UPPER 60S OVER THE
NORTHWESTERN RANCH LANDS TO THE MID 60S ACROSS THE LOWER VALLEY.
NORTH SFC WINDS UNDER WEST FLOW ALOFT WILL RESULT IN
OVERRUNNING...AND CLOUDINESS WILL BE THICKER ALONG THE SOUTHERN
BORDER...OR IVO THE RIO GRANDE.

CLOUD COVER WILL REMAIN IN PLACE AT THE LOWER LEVELS...EVEN AS THE
MID LEVELS DRY OUT. SOUTHWEST CAPPING FLOW AT H7...OR 10 KFT...WILL
SEE TO THAT. OVERNIGHT LOW TEMPS WILL RANGE FROM THE UPPER 40S
ACROSS THE NORTHERN RANCH LANDS TO THE MID 50 AT KBRO AND KSPI.
CLOUDINESS AND COOLER WEATHER WILL CONTINUE ON SATURDAY...WITH HIGH
TEMPS MAINLY IN THE MID 60S...JUST BELOW NORMAL FOR THIS TIME OF THE
YEAR. RAIN CHANCES WILL DIMINISH. ANOTHER SHORTWAVE TROUGH WILL
APPROACH FROM THE WEST...OR FROM NORTH CENTRAL MEXICO...AND THE
UPPER FLOW PATTERN WILL THUS NOT REALLY ALLOW FOR A CLEARING OUT
DURING THE SHORT TERM. OVERALL RAIN CHANCES WILL BE LESS THAN
TONIGHT.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...MID LEVEL S/W
TROUGH WILL BE MOVING ACROSS NORTHERN MEXICO SATURDAY NIGHT THEN
ACROSS TEXAS SUNDAY. WEAK SFC LOW PRESSURE WILL DEVELOP IN THE
WESTERN GULF IN RESPONSE TO THE MID LEVEL FEATURE THEN MOVE INTO
THE CENTRAL GULF SUNDAY NIGHT. UPPER FORCING AND ISENTROPIC LIFT
ON THE NORTH AND WEST SIDE OF THE SFC LOW WILL BE SUFFICIENT
ENOUGH TO DEVELOP SHOWERS OVER THE GULF WATERS WHICH WILL MOVE
NORTHWESTWARD INTO DEEP SOUTH TEXAS SATURDAY NIGHT THROUGH SUNDAY
WITH CHANCES WANING SUNDAY NIGHT AS THE LOW AND S/W TROUGH MOVES
EASTWARD. HAVE CHANCE POPS ALONG AND EAST OF HWY 281 WITH HIGHER
POPS OVER THE GULF WATERS. MONDAY WILL BE DRY WITH SUBSIDENCE ON
THE BACK SIDE OF THE TROUGH AND DRY AIR WORKS IN ON WESTERLY FLOW
ALOFT. ANOTHER S/W TROUGH WILL MOVE INTO THE HEART OF THE NATION
MONDAY WITH ADDITIONAL ENERGY MOVING INTO THE SOUTHERN PLAINS
TUESDAY WHICH WILL SUPPORT A COLD FRONTAL PASSAGE TUESDAY. MODELS
ARE TRENDING STRONGER WITH THIS OVERALL SYSTEM SO HAVE EDGED WINDS
UP WHILE NUDGING TEMPERATURES AND DEW POINTS DOWN SLIGHTLY. HAVE
ALSO INTRODUCED SHOWERS ACROSS THE GULF WATERS AS MOISTURE APPEARS
SUFFICIENT FOR AT LEAST PRECIPITATION THERE. SURFACE RIDGING WORKS
IN BEHIND THE FRONT FOR CHRISTMAS EVE WITH FAIRLY BENIGN WEATHER
EXPECTED WITH NEAR NORMAL HIGHS IN THE LOWER 70S. THE NEXT S/W
TROUGH ENTERS THE PACIFIC NORTHWEST WEDNESDAY WITH LEE TROUGH
STRENGTHENING ACROSS THE HIGH PLAINS THURSDAY. WAA AND
STRENGTHENING WINDS EXPECTED FOR CHRISTMAS DAY WITH HIGHS JUMPING
UP TO THE MIDDLE 70S... PARTLY CLOUDY SKIES... AND BREEZY
SOUTHERLY WINDS.

MARINE /TODAY THROUGH SATURDAY/...LIGHT TO MODERATE SOUTH WINDS
WILL TURN TO FRESH OR STRONG NORTH LATER TODAY AS A COLD FRONT
MOVES THROUGH THE AREA. SEAS WILL BE LOW TO MODERATE. THE GRADIENT
WILL TIGHTEN WITH A PUSH OF HIGH PRESSURE THIS EVENING AND
TONIGHT...WHEN NORTH WINDS ON THE GULF WILL APPROACH 20 KTS. SEAS
WILL BUILD TO JUST SHY OF SEVEN FEET. THUS...A FEW HOURS OF
ADVISORY CONDITIONS WILL BE POSSIBLE ON THE GULF WATERS TONIGHT
AND THE FIRST PART OF SATURDAY MORNING... WITH CONDITIONS SETTLING
DOWN THE REST OF SATURDAY.

/SATURDAY NIGHT THROUGH TUESDAY/...MORE MODERATE NORTHEAST
WINDS ARE EXPECTED SATURDAY NIGHT AND SUNDAY WITH A SLIGHT UPTICK IN
THE SEAS AS WEAK SFC LOW PRESSURE DEVELOPS IN THE SOUTHWEST GULF. AS
THIS FEATURE MOVES EASTWARD SUNDAY NIGHT HIGH PRESSURE BUILDS IN FOR
MONDAY WITH LIGHT AND VARIABLE WINDS BECOMING SOUTHERLY BY LATE
MONDAY AFTERNOON. A COLD FRONT IS EXPECTED TO MOVE THROUGH THE
COASTAL WATERS TUESDAY WITH STRONG NORTHWESTERLY WINDS IN ITS WAKE
AND SEA HEIGHTS RISING TO NEAR 7 FEET. SMALL CRAFT ADVISORIES ARE
POSSIBLE FOR TUESDAY.

&&

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

$$

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