Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 171800 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1200 PM CST WED DEC 17 2014

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

.AVIATION...SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE A
MIX OF LOW CLOUDS AND HIGH CLOUDS ACROSS THE CWA LATE THIS
MORNING. CEILINGS WERE NEAR 300FT AT KAPY TO NEAR 4200FT AT KBKS.
VISIBILITIES WERE NEAR 4SM WITH FOG AT KAPY. EXPECT VFR CONDITIONS
TO PREVAIL ACROSS MOST OF THE CWA THIS AFTERNOON INTO THIS EVENING AS
THE WARM FRONT ACROSS THE EXTREME WESTERN PORTIONS LIFTS
NORTHWARD. MVFR CONDITIONS WILL LIKELY RETURN TONIGHT WITH IFR
CONDITIONS LATE TONIGHT INTO EARLY THURSDAY MORNING AS MOISTURE
CONTINUES TO POOL ALONG THE WARM FRONT DRAPED JUST NORTH OF THE CWA
TONIGHT.
&&

.PREV DISCUSSION... /ISSUED 531 AM CST WED DEC 17 2014/
DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...IR SATL DEPICTS MULTILAYERED CLOUD DECKS STREAMING
MAINLY SOUTHWEST TO NORTHEAST ACROSS THE AREA. THERE ARE POCKETS
OF IFR/LOW MVFR CIGS BUT HARD TO SEE WITH SATL WITH SO MUCH MID/HIGH
LEVEL CLOUDS OVERHEAD. WARM FRONT HAS MOVED THROUGH THE VALLEY
WITH WIND DIRECTIONS FROM THE SOUTHEAST WITH MORE NORTHEASTERLY
NORTH OF THE FRONT FROM HBV-BKS NORTHWARD. SOUTHEASTERLY WINDS
WILL CONTINUE TODAY WITH GUSTS IN THE AFTERNOON 20-22 KNOTS. ASIDE
FROM TEMPO MVFR/IFR THIS MORNING...PREDOMINATE VFR THROUGH THE
AFTERNOON HOURS. MVFR WILL RETURN AFTER SUNSET AS COOLING
COMMENCES AND CLOUD DECKS LOWER.

PREV DISCUSSION... /ISSUED 350 AM CST WED DEC 17 2014/

SHORT TERM /NOW THROUGH THURSDAY/...COLD FRONT THAT MOVED
THROUGH THE AREA YESTERDAY HAS STALLED JUST SOUTH OF THE RIVER
AND IS EXPECTED TO MOVE BACK NORTHWARD AS A WARM FRONT THIS
MORNING AS AN UPPER TROUGH MOVES ACROSS THE WESTERN CONUS AND
CYCLOGENESIS OCCURS OVER NORTHEAST NEW MEXICO. ISENTROPIC LIFT IS
OCCURRING NOW WITH 00Z BRO SOUNDING SHOWING A MOIST SFC-800 MB
LAYER UNDERNEATH DRY MID/UPPER LEVEL AIR AND SOUTHERLY FLOW RIDING
OVER EASTERLY SFC FLOW. BRO RADAR THIS MORNING SHOWS ISOLATED TO
WIDELY SCATTERED SHOWERS DEVELOPING NORTH OF THE BOUNDARY ACROSS
MUCH OF DEEP SOUTH TEXAS. TEMPERATURES WERE MAINLY IN THE MID 60S
IN THE VALLEY TO AROUND 60 IN THE RANCH LANDS. MINOR CHANGES WERE
MADE TO EXPAND CHANCE COVERAGE INTO THE NORTHERN GULF BUT THAT WAS
ABOUT IT THROUGH 12Z.

WARM FRONT WILL LIFT NORTH OF THE AREA BY EARLY THIS AFTERNOON
TAKING MOST PRECIPITATION NORTHWARD WITH IT. SOUTHEAST SFC WINDS
RETURN SOUTH OF THE FRONT WITH AN UPTICK IN WINDS LATE THIS
MORNING INTO THE AFTERNOON HOURS WITH GUSTS TO 25 MPH. FURTHER
WEST ACROSS ZAPATA...TROUGHING WILL DEVELOPING WITH WINDS MAINLY
ON THE LIGHT SIDE TODAY. HIGHS WILL MAKE MID TO UPPER 70S ACROSS
MUCH OF THE AREA...A LITTLE LOWER ACROSS THE FAR WESTERN SECTIONS.

FRONT WILL HANG OUT NORTH OF THE AREA THROUGH WEDNESDAY NIGHT AND
THURSDAY. AS THE UPPER TROUGH GETS CLOSER...LEE TROUGHING
STRENGTHENS ACROSS NORTHERN MEXICO WITH WEAK CONVERGENCE ACROSS
THE WEST AND WEAK UPPER DIFFLUENCE OVERSPREADING THE AREA. RAIN
CHANCES COME BACK UP THURSDAY WITH CHANCE POPS ACROSS MOST OF THE
AREA BY THURSDAY AFTERNOON.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...A WEAK REMNANT
FRONTAL BOUNDARY WILL TEASE DEEP SOUTH TEXAS THURSDAY NIGHT...
LYING OVER THE AREA AND MAINTAINING A SLIGHT CHANCE OF LIGHT RAIN
IN AN OVERRUNNING SITUATION. A MID LEVEL SHORT WAVE TROUGH
UPSTREAM OVER WEST TEXAS WILL KEEP SOME DOWNSTREAM LIFT OVER THE
AREA...THOUGH MOST OF THE ENERGY WILL BE FOCUSED NORTH OF THE BRO
CWA. NONETHELESS...A SURFACE COLD FRONT WILL MOVE THROUGH THE
AREA FRIDAY AROUND MID DAY AS THE MID LEVEL TROUGH AXIS SWINGS
OVER THE NORTH AND CENTRAL PARTS OF TEXAS. SCATTERED SHOWERS AND A
FEW THUNDERSTORMS MAY DEVELOP ALONG THE COAST AND MOVE OFFSHORE
FRIDAY MORNING THROUGH AFTERNOON...BUT DRY AIR WILL MOVE IN
RAPIDLY LATE FRIDAY...CLEARING OUT UNSETTLED WEATHER. THE MODELS
APPEAR TO BE IN PRETTY GOOD AGREEMENT WITH THE ABOVE SCENARIO.

ABOVE AVERAGE TEMPS THURSDAY NIGHT AND FRIDAY WILL DECREASE
SATURDAY NIGHT HOWEVER...LANDING MUCH CLOSER TO NORMAL WITH SOME
MID TO UPPER 40S ACROSS THE NORTHERN RANCH LANDS AND BRUSH
COUNTRY. NORMAL HIGH TEMPERATURES SATURDAY IN THE MID 60S WILL
SEEM COOL. HIGH PRES WILL SPREAD OVER THE AREA IN THE WAKE OF THE
FRONT WITH NEAR NORMAL TEMPERATURES PERSISTING THROUGH MONDAY
THOUGH A SLOW WARMING TREND WILL BE UNDERWAY.

ANOTHER LOW LATITUDE MID LEVEL TROUGH WILL TRACK INTO WEST TEXAS
SATURDAY NIGHT. THE LIFT WILL INCREASE MOISTURE OVER THE AREA ON
SUNDAY AS SURFACE WINDS ARE VEERING TO EAST. AS THE TROUGH CLEARS
TO THE EAST...DRIER AIR WILL AGAIN FILTER IN FROM THE WEST WITH
HIGH TEMPERATURES ON TUESDAY IN THE 70S WITH SIGNIFICANT MID LVL
RIDGING BUILDING UPSTREAM. INDEED...HIGH PRESSURE WILL ARRIVE AS A
DRY FRONT ON TUESDAY WITH NORTH WINDS AND SUBSEQUENTLY SLIGHTLY
COOLER TEMPS.

MARINE...
NOW THROUGH THURSDAY...SEAS WERE NEAR 4 FEET WITH EAST-SOUTHEAST
WINDS NEAR 15 KNOTS WITH GUSTS NEAR 19 KNOTS AT BUOY020 EARLY THIS
MORNING. WINDS WILL VEER TO THE SOUTHEAST TODAY AS THE WARM FRONT
TO OUR SOUTH CONTINUES TO MOVE NORTHWARD INTO SOUTH TEXAS BY THIS
AFTERNOON. MARINERS WILL NEED TO EXERCISE CAUTION ACROSS THE GULF
WATERS THIS MORNING BEFORE WINDS DECREASE THIS AFTERNOON. MODERATE
SOUTHEAST WINDS CAN BE EXPECTED TONIGHT AND THURSDAY WITH SEAS
FALLING TO AROUND 3 FEET.

THURSDAY NIGHT THROUGH SUNDAY...THE MAIN IMPACT PERIOD WILL BE
FRIDAY NIGHT INTO SATURDAY MORNING AS NORTH WINDS BEHIND A FRONT
INCREASE TO AROUND 20 KNOTS AND SEAS BUILD TO BETWEEN 5 AND 7 FEET.
A FEW HOURS OF LOW END SMALL CRAFT ADVISORY CONDITIONS MAY DEVELOP.

THURSDAY NIGHT...HIGH PRESSURE OVER THE NORTH GULF WILL RETREAT
WHILE LOWER PRESSURE DEVELOPS OVER SOUTH TEXAS AS A MID LEVEL
SHORT WAVE TROUGH APPROACHES ACROSS THE DESERT SOUTHWEST. MDT
SOUTHEAST WINDS WILL PERSIST THROUGH THE NIGHT AND WILL THEN SHIFT
TO SOUTH EARLY FRIDAY IN ADVANCE OF A COLD FRONT ARRIVING AROUND
MID DAY. SCATTERED SHOWERS WILL DEVELOP FRIDAY WITH THE FRONT...
BUT IT LOOKS LIKE MOST OF THE ENERGY WILL BE FARTHER TO THE NORTH.
MODERATE TO BREEZY NORTH WINDS AND HIGHER SEAS WILL SET UP BEHIND
THE FRONT THROUGH FRIDAY NIGHT. A FEW HOURS OF LOW END SMALL CRAFT
ADVISORY CONDITIONS MAY DEVELOP. THE WEATHER WILL CLEAR UP FRIDAY
AS DRIER AIR ARRIVES. HIGH PRESSURE WILL SPREAD OVER THE AREA
SATURDAY WITH MODERATE WINDS SHIFTING TO NORTHEAST WHILE SEAS
REMAIN MDT THOUGH SLOWLY DECREASING. BY SATURDAY NIGHT WINDS WILL
BE OUT OF THE EAST WHILE A MID LEVEL SHORTWAVE TROUGH APPROACHES ON
A LOW LATITUDE TRAJECTORY...SWINGING OVER WEST TEXAS SATURDAY
NIGHT. THE TROUGH WILL RESULT IN UNSETTLED WEATHER SATURDAY NIGHT
THROUGH SUNDAY NIGHT...WITH DRIER AIR OF SIMILAR PRESSURE ARRIVING
IN THE NORTH WEST GULF...SHIFTING WINDS MORE TO SOUTHEAST AGAIN.
&&

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

$$

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