Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 201827 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
127 PM CDT WED MAY 20 2015

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

&&

.AVIATION...DAYTIME HEATING IS PRODUCING A PRETTY GOOD FIELD OF
FAIR WX CU OVER THE RGV RESULTING IN VFR CEILINGS WITH A FAIRLY
BRISK SE SURFACE FLOW PREVAILING. THE LATEST NAM FORECAST
SOUNDINGS SHOW THAT ANOTHER FAIRLY MOIST LAYER WILL REFORM LATER
TONIGHT AFTER SUNSET WHICH SHOULD ALLOW THE OVERNIGHT CEILINGS TO
PERIODICALLY FALL TO MVFR LEVELS. ALTHOUGH THE CONV OUTLOOK FROM
SPC FOR THURS PLACES A GOOD CHUNK OF THE RGV IN A MARGINAL SVR WX
POTENTIAL EXPECT THE BEST CONV POTENTIAL TO FALL OUTSIDE THE 18Z
THURS END POINT OF THE CURRENT TAF SET. SO WILL LEAVE OUT ANY
MENTION OF CONV IN THE CURRENT TAF ISSUANCE FOR THE MOMENT.
MVFR/VFR CONDITIONS TO PREVAIL THROUGH THE NEXT 24 HOURS.

&&

.PREV DISCUSSION... /ISSUED 426 AM CDT WED MAY 20 2015/

DISCUSSION...INCLUDED SMALL CRAFT ADVISORY FOR WINDS OVER THE
LAGUNA MADRE AS THE INTERACTION OF THE LEE SIDE TROUGH TO THE
WEST WITH HIGH PRESSURE DOMINATING OVER THE GULF WILL ALLOW FOR
STRONGER WINDS TO MIX DOWN AND INCREASE SE WINDS OVER THE LAGUNA
MADRE. SMALL CRAFT SHOULD EXERCISE CAUTION OVER THE GULF WATERS.

PREV DISCUSSION... /ISSUED 333 AM CDT WED MAY 20 2015/

SHORT TERM /NOW THROUGH THURSDAY/...IR SATELLITE IMAGERY AND 500 MB
HEIGHTS CURRENTLY SHOW A WEST TO SOUTHWESTERLY FLOW ACROSS THE NORTHERN
MX WHILE RIDGE BUILDS OVER SOUTH TX. MID LEVEL IMPULSE OVER THE PACIFIC
COAST WILL DIG SOUTHWARD BEFORE ENTERING BAJA CA AND LIFT NORTHEAST IN
DIRECTIONS TOWARDS THE ROCKIES THURSDAY. NEAR THE SFC...A WEAK FRONTAL
WAVE MOVES SOUTH ACROSS THE CENTRAL PLAINS UNTIL IT DECAYS OVER NORTH
CENTRAL TX DUE TO BROAD ANTICYCLONE SHIFTING FROM THE HIGH C PLAINS
TOWARDS THE EAST.

TODAY...DRY AND STABLE CONDITIONS CONTINUE AS RIDGE IS DOMINATING OVER
SOUTH TEXAS. LOW LEVEL MOISTURE WITH DAY TIME MIXING WILL ALLOW FOR A
FEW CLOUDS IN THE AFTERNOON WITH ABUNDANT SUNSHINE. MOST OF THE DEEPER
LAYER MOISTURE WILL REMAIN CONFINED TO THE NORTH OF THE AREA THROUGH
WEDNESDAY NIGHT LIMITING ANY CONVECTION. DUE TO THE ABUNDANCE SUNSHINE
.HIGH TEMPERATURES WILL BE ALMOST CARBON COPIED OF TUESDAY TEMPERATURES
REACHING THE MID 90S OVER THE NORTHERN RANCHLANDS AND THE UPPER 80S NEAR
THE COAST.

TONIGHT INTO THURSDAY...CONDITIONS BEGIN TO CHANGE AS THE MID LEVEL WAVE
MOVES INTO THE DESERT SOUTHWEST INCREASING THE DIFFLUENCE ALOFT WHILE THE
FRONT REMAINS ALMOST STATIONARY OVER NORTH CENTRAL TEXAS THURSDAY. LOW`S
TEMPS ACROSS THE CWA REACH THE MID TO UPPER 70S AND LOW 70S TO THE NORTH.
DUE TO THE FRONT INTERACTION AND BROAD HIGH OVER THE GULF...SE FLOW WILL
CONTINUE WITH WINDS INCREASING DURING THE DAY. PRECIPITABLE WATER VALUES
ALSO INCREASE FROM 1.6 TO 1.9 INCHES. LOW/DEEP LAYER FLOW WILL BE WEAK
WITH BETTER INSTABILITY TOWARDS THE NORTHWEST BUT WINDS VEERING WITH
HEIGHT WHICH COULD ENHANCE A COUPLE OF CLUSTERS OF THUNDERSTORMS OVER THE
NORTHWEST PORTION OF THE CWA. THE MAIN THREAT WITH SOME OF THE STORMS THAT
DEVELOP WILL BE LARGE HAIL AND STRONG WINDS. SHOWER AND ISOLATED THUNDERSTORMS
WILL BE POSSIBLE NEAR THE VALLEY BUT MORE STABLE CONDITIONS WILL ALLOW FOR
LESS CHANCE OF STRONG STORMS TO DEVELOP. THE LOW LEVEL FLOW BETWEEN SFC FRONT
AND HIGH PRESSURE OVER THE GULF WILL SURGE DEEPER MOISTURE NORTH AND ALONG
THE SIERRA MADRE INCREASING THE POTENTIAL FOR MORE RAINFALL THURSDAY NIGHT.
HIGH TEMPERATURES WITH INCREASE IN CLOUD COVER WILL STILL BE NEAR 90S.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...LOW TO MID LEVEL
MOISTURE WILL BE HIGH ACROSS PORTIONS OF NORTHWEST AND NORTH
TEXAS THURS NIGHT INTO FRIDAY AS A 500MB LOW/TROUGH MOVES INTO
SOUTHERN CALIFORNIA FRIDAY. RAIN CHANCES WILL DEVELOP ACROSS THE
WESTERN PORTIONS OF THE CWA THURS NIGHT AND SPREAD EASTWARD
FRIDAY. THE UPPER LEVEL LOW/TROUGH IS EXPECTED TO MOVE INTO THE
SOUTHWEST UNITED STATES SATURDAY AND WITH MOISTURE REMAINING HIGH
ACROSS THE STATE THROUGH THE WEEKEND...A SLIGHT CHANCE TO CHANCE OF
SHOWERS AND THUNDERSTORMS WILL CONTINUE SATURDAY AND SUNDAY WITH
THE BEST CHANCE OF RAIN SUNDAY AS THE 500MB TROUGH ACROSS
NORTHWEST MEXICO MOVES EASTWARD. WILL KEEP A CHANCE OF RAIN EARLY
NEXT WEEK BEFORE THE SHORTWAVE TROUGH MOVES ACROSS THE SOUTHERN
PLAINS TUESDAY AND A SOMEWHAT ZONAL FLOW DEVELOPS ACROSS THE
SOUTHERN U.S. TOWARDS THE MIDDLE OF NEXT WEEK.

MARINE...
NOW THROUGH THURSDAY...RELATIVELY COOLER BAY AND SURF WATER TEMPS
IN THE UPPER 70S TO LOWER 80S WILL TEND TO LIMIT THE SURFACE
MARINE WINDS OVER THE LOWER TX MARINE AREAS THROUGHOUT THE SHORT
TERM PERIOD AS THE VERY WARM SE SURFACE FLOW CONTINUES. EXPECT
SEAS TO BUILD CLOSE TO 6 FEET OFFSHORE TODAY WITH SCEC OVER THE
GULF WATER FOR THE EARLY MORNING TODAY BUT IMPROVING INTO THIS
AFTERNOON. NO CHANCE OF SHOWERS IS EXPECTED WITH LOTS OF SUNSHINE.
THURSDAY SOUTHEAST WINDS WILL PICK UP ONCE AGAIN IN THE AFTERNOON
WITH A FEW ISOLATED SHOWERS AND THUNDERSTORMS POSSIBLE. SEAS WILL
REMAIN BETWEEN 2 TO 4 FEET.

THURSDAY NIGHT THROUGH SUNDAY...MODERATE SOUTHEAST WINDS WILL
PREVAIL ACROSS THE COASTAL WATERS THURS NIGHT INTO FRIDAY WITH
HIGH PRESSURE ACROSS THE EASTERN HALF OF THE COUNTRY AND LOW
PRESSURE ACROSS WEST TEXAS. WINDS AND SEAS WILL INCREASE SATURDAY
AS THE PRESSURE GRADIENT INCREASES ACROSS THE WESTERN GULF OF
MEXICO. MODERATE TO STRONG SOUTHEAST WINDS SATURDAY WILL CONTINUE
SUNDAY AND SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED FOR THE
OFFSHORE WATERS OF THE LOWER TEXAS COAST FRI NIGHT THROUGH SUNDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  78  87  77  86 /  10  20  20  20
BROWNSVILLE          79  89  76  88 /  10  20  20  30
HARLINGEN            78  90  75  89 /  10  20  20  30
MCALLEN              77  92  75  90 /  10  30  30  30
RIO GRANDE CITY      77  92  75  90 /  20  40  30  30
SOUTH PADRE ISLAND   79  84  77  83 /  10  20  10  30

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 PM CDT THIS EVENING FOR
     GMZ130-132-135.

&&

$$

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

SHORT TERM...60
LONG TERM...55


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