Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 310548 AAB
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1148 PM CST FRI JAN 30 2015

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

&&

.AVIATION...HIGH CLOUDS AROUND 6 KFT AND HIGHER WILL CONTINUE TO
STREAM ACROSS SOUTH TEXAS THROUGH THE NIGHT AND INTO TOMORROW AS A
DISTURBANCE MOVES INTO THE FOUR CORNERS REGION. SURFACE HIGH
PRESSURE WILL BEGIN TO SHIFT EAST VEERING WINDS TO THE SOUTHEAST
THROUGH THE NIGHT AND BECOMING LIGHT. THIS LIGHT WINDS AND HIGH
MOISTURE CONTENT WILL PROVIDE FAVORABLE CONDITIONS FOR AREAS OF
FOG AFTER MIDNIGHT. GRADIENT WILL STRENGTHEN TOMORROW INCREASING
SE WINDS WITH GUSTY WINDS PREVAILING THROUGH THE DAY BECOMING LIGHT
SATURDAY EVENING.

&&

.PREV DISCUSSION... /ISSUED 620 PM CST FRI JAN 30 2015/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...HIGH CLOUDS WILL CONTINUE TO STREAM ACROSS SOUTH
TEXAS THROUGH THE NIGHT AND INTO TOMORROW AS A DISTURBANCE
MOVES INTO THE FOUR CORNERS REGION. SURFACE HIGH PRESSURE WILL
BEGIN TO SHIFT EAST VEERING WINDS TO THE SOUTHEAST THROUGH THE
NIGHT. LIGHT WINDS WITH MOISTURE IN THE AREA WILL PROVIDE
FAVORABLE CONDITIONS FOR AREAS OF FOG AFTER MIDNIGHT. GRADIENT
WILL STRENGTHEN TOMORROW INCREASING SE WINDS WITH GUSTY WINDS
PREVAILING THROUGH THE DAY.

PREV DISCUSSION... /ISSUED 341 PM CST FRI JAN 30 2015/

SHORT TERM /NOW THROUGH SATURDAY NIGHT/...

RELEVANT FEATURES...A COLD FRONT...LARGELY IN NAME ONLY...HAS
CLEARED THE REGION AND IS NOW SITUATED ABOUT 50 MILES SOUTH OF
THE RIO GRANDE. MODEST NORTHEASTERLY WINDS HAVE SETTLED IN BEHIND
THE FRONT BUT ARE GRADUALLY SHIFTING MORE TO THE EAST AS HIGH
PRESSURE SHIFTS ACROSS THE PLAINS. A RELATIVELY LARGE UPPER
TROUGH/EMBEDDED CLOSED LOW IS SPINNING OFF THE CALIFORNIA COAST
WITH BROAD JET MOMENTUM MOSTLY TO ITS EAST HELPING TO SLOW THE
TROUGHS OVERALL EASTWARD PROGRESSION. THE AIR JUST OFF THE SURFACE
IS PRETTY DRY AND SUNSHINE IS WORKING THROUGH IN SEVERAL
SPOTS...ESPECIALLY NORTH OF THE VALLEY.

TONIGHT...SURFACE WINDS SPEEDS WILL FALL THROUGH THE NIGHT AND
GRADUALLY TURN TOWARDS THE SOUTHEAST AS LOCAL INFLUENCE FROM THE
APPROACHING UPPER TROUGH INCREASES. SURFACE DEWPOINTS/MOISTURE HAS
NOT REALLY DROPPED ALL THAT MUCH FROM 24 HOURS AGO AND DID INTRODUCE
A MENTION OF PATCHY FOG IN THE RGV METRO AREAS AGAIN TONIGHT DUE TO
THE SLACKENING WINDS UNDER BROKEN CIRRUS CLOUDS. SLIGHT RAIN CHANCES
CREEP INTO THE NORTHWESTERN ZONES TONIGHT AS UPPER DIFFLUENCE
INCREASES TO THE WEST BUT AMOUNTS SHOULD BE LOW AND THE VALLEY WILL
LIKELY REMAIN DRY.

SATURDAY...SOUTHEASTERLY RETURN FLOW WILL PICK UP QUICKLY IN THE
MORNING SETTING THE STAGE FOR A BREEZY DAY. WIND GUSTS WILL LIKELY
PUSH INTO THE 25 TO 30 MPH RANGE BY EARLY AFTERNOON. INCREASING
MOISTURE WILL BE RIDING ON THOSE SOUTHEASTERLIES WHICH WILL KEEP A
RAIN CHANCE IN PLACE IN ZAPATA/JIM HOGG/BROOKS COUNTIES WHERE
PERSISTENT BROAD DIFFLUENCE WILL REMAIN IN PLACE ALOFT. ALSO
CONTINUED A SLIGHT CHANCE OF MORNING SHOWERS IN THE COASTAL COUNTIES
BUT THE BULK OF THE DAY SHOULD BE DRY IN THE METRO AREAS.
TEMPERATURES WILL BE CLOSE TO TODAY OR SLIGHTLY WARMER...LOW TO MID
70S FOR HIGHS.

SATURDAY NIGHT...JET ACTIVITY ON THE EAST SIDE OF THE SLOWLY
ADVANCING UPPER LOW BECOMES STRONGER DURING THE LATE AFTERNOON AND
EVENING SATURDAY AND WE WILL BE JUST SOUTHEAST OF A MODERATELY
DIVERGENT LEFT EXIT REGION OF A 100KT SPEED MAX DURING THE NIGHT.
THE MID LEVEL ASCENT FROM THIS SHOULD HELP GET A FEW SHOWERS GOING
AND HAVE RAIN CHANCES IN THE 30 TO 40 PCT RANGE DURING THE NIGHT.
THE GFS/NAM BOTH APPEAR TO GENERATE SPURIOUS VORTICITY MAXIMA IN THE
RAPID SOUTHWEST FLOW OVER THE SIERRA MADRE MOUNTAINS AND THAT
CREATES MORE CONVECTION/QPF THAN THE LOW LEVELS OF ELEVATED
INSTABILITY AND SYNOPTIC FORCING WOULD SUGGEST. THE ECMWF IS
PREFERRED HERE SHOWING SOME HIT OR MISS SHOWERS/LOW END QPF AROUND
0.05 TO 0.10 INCHES WHICH AGREES WITH THE EXISTING SYNOPTIC PATTERN.
/68-JGG/

LONG TERM /SUNDAY THROUGH FRIDAY/...500MB SHORTWAVE TROUGH ACROSS
THE NORTHERN PLAINS SUNDAY WILL MOVE EASTWARD MONDAY AS A 500MB
LOW CUTS OFF ACROSS SOUTHERN BAJA CALIFORNIA. FRONTAL WAVE ACROSS
THE SOUTHERN PLAINS SUNDAY WILL BRING A COLD FRONT THROUGH THE RIO
GRANDE VALLEY SUN NIGHT INTO EARLY MONDAY AS THE LOW PRESSURE
ASSOCIATED WITH THE FRONTAL SYSTEM MOVES EASTWARD. RAIN CHANCES
WILL DEVELOP SUN NIGHT ALONG AND AHEAD OF THE FRONT BUT DIMINISH
MONDAY AS DRIER AIR FILTERS INTO SOUTH TEXAS FROM THE NORTH. A
COASTAL LOW/TROUGH IS EXPECTED TO DEVELOP ACROSS THE WESTERN GULF
OF MEXICO MON NIGHT INTO TUESDAY AND OVERRUNNING CONDITIONS WILL
DEVELOP ACROSS THE RIO GRANDE VALLEY. RAIN CHANCES WILL INCREASE
WILL MON NIGHT INTO TUESDAY WITH COOLER TEMPERATURES MONDAY AND
TUESDAY. RAIN CHANCES SHOULD DIMINISH FROM WEST TO EAST TUES NIGHT
INTO WEDNESDAY AS THE 500MB LOW ACROSS SOUTHERN BAJA CA FINALLY
MOVES NORTHEAST ACROSS SOUTHWEST TX WEDNESDAY. WARMER AND DRIER
CONDITIONS SHOULD PREVAIL WEDNESDAY AND THURSDAY BEFORE ANOTHER
COLD FRONT REACHES THE RIO GRANDE VALLEY FRIDAY.

MARINE...
NOW THROUGH SATURDAY NIGHT... GUSTY NORTHEAST WINDS WILL
CONTINUE THROUGH THE AFTERNOON BEFORE WIND SPEEDS DECREASE AND
SLOWLY SHIFT TO THE SOUTHEAST. WINDS WILL INCREASE AGAIN DURING THE
DAY SATURDAY AND EXERCISE CAUTION OR POSSIBLY SMALL CRAFT ADVISORY
CONDITIONS ARE POSSIBLE ON THE LAGUNA MADRE TOMORROW WITH GENERALLY
MODERATE WINDS AND SEAS ON THE GULF OF MEXICO. BREEZY CONDITIONS ARE
FORECAST ON THE GULF OF MEXICO SATURDAY NIGHT WITH WINDS AND SEAS
LIKELY BELOW EXERCISE CAUTION LEVELS.

SUNDAY THROUGH WEDNESDAY...LIGHT TO MODERATE SOUTH WINDS WILL
PREVAIL ACROSS THE COASTAL WATERS SUNDAY BEFORE A STRONG COLD
FRONT MOVES THROUGH THE LOWER TEXAS COAST LATE SUN NIGHT INTO
EARLY MON MORNING. STRONG NORTH WINDS WITH GUSTS TO NEAR GALE
FORCE WILL BE POSSIBLE MONDAY INTO MON NIGHT IN THE WAKE OF THE
FRONT. SMALL CRAFT ADVISORIES WITH POSSIBLE GALE WATCHES/WARNINGS
WILL BE NEEDED MONDAY AS A RESULT. WINDS AND SEAS WILL REMAIN HIGH
TUESDAY AS THE PRESSURE GRADIENT REMAINS STRONG ACROSS THE LOWER
TEXAS COAST AS A COASTAL LOW/TROUGH DEVELOPS ACROSS THE WESTERN
GULF OF MEXICO. SMALL CRAFT ADVISORIES WILL LIKELY CONTINUE
TUESDAY THROUGH TUES NIGHT. MODERATE TO STRONG NORTH TO NORTHEAST
WINDS TUESDAY WILL BACK TO THE NORTHWEST AND WEAKEN WEDNESDAY AS
THE COASTAL LOW/TROUGH MOVES NORTHEAST WEDNESDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  61  70  61  74 /  20  20  30  20
BROWNSVILLE          60  72  61  76 /  20  20  30  20
HARLINGEN            56  72  60  77 /  10  20  30  20
MCALLEN              59  73  60  79 /  10  20  30  20
RIO GRANDE CITY      60  74  59  79 /  20  20  40  20

&&

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

$$

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

67...AVIATION
59...SHORT TERM


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