Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 231150 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
650 AM CDT TUE SEP 23 2014

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

&&

.AVIATION...SOME PATCHY CONV IS MOVING PRETTY STEADILY SOUTHWEST
JUST OFFSHORE OF KENEDY COUNTY THIS MORNING. THIS ACTIVITY LOOKS
LIKE IT WILL LIKELY SWEEP A LITTLE WEST OF THE RGV. HOWEVER WILL
INCLUDE SOME MENTION OF VCSH DURING THE LATE MORNING HOURS. SINCE
THE 00Z BRO SOUNDING SHOWS SOME FAIRLY DRY AIR IN PLACE OVER THE
AREA EXPECT THE CONV COVERAGE TO REMAIN FAIRLY LIMITED DURING THE
REST OF THE DAY. WILL MAINTAIN OVERALL VFR CONDITIONS THROUGH THE
UPCOMING TAF PERIOD.

&&

.PREV DISCUSSION... /ISSUED 605 AM CDT TUE SEP 23 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...MOSTLY CLEAR SKIES AND LIGHT WINDS PREVAIL ACROSS DEEP
SOUTH TEXAS THIS MORNING. PATCHY FOG MAY DEVELOP AND IMPACT TAF
SITES...REDUCING VISIBILITIES TO MVFR LEVELS NOW THROUGH 14Z.
OTHERWISE...VFR CONDITIONS AND LIGHT TO MODERATE NORTHEAST TO EAST WINDS
WILL PREVAIL ACROSS THE REGION FOR THE NEXT 24 HOURS. SPOTTY
SHOWERS AND THUNDERSTORMS WILL DEVELOP LATER THIS MORNING INTO THE
AFTERNOON HOURS BUT WILL ONLY MENTION VCSH DUE TO LOW CONFIDENCE.

PREV DISCUSSION... /ISSUED 425 AM CDT TUE SEP 23 2014/

SHORT TERM /NOW THROUGH WEDNESDAY/...DRIER AIR IN THE MID LEVELS
CONTINUES ACROSS DEEP SOUTH TEXAS THIS MORNING WITH THE 0Z BRO
SOUNDING INDICATING A PRECIPITABLE WATER VALUE OF 1.72 INCHES.
BROWNSVILLE RADAR CURRENTLY SHOWING SCATTERED SHOWERS ABOUT 80 MILES
SOUTH OF THE RIO GRANDE RIVER ASSOCIATED WITH A STATIONARY FRONT.
RADAR ALSO SHOWS CONVECTION INCREASING JUST NORTHEAST OF THE LOWER
TEXAS GULF WATERS IN RESPONSE TO MID LEVEL ENERGY PER LATEST NAM AND
WATER VAPOR IMAGERY. MOSTLY CLEAR SKIES...LIGHT WINDS AND THE WET
GROUND FROM RECENT RAINS HAS ALLOWED SOME PATCHY FOG TO
DEVELOP...MAINLY ACROSS THE MID VALLEY...THIS MORNING.

TODAY...PATCHY FOG POSSIBLE THROUGH MID MORNING. OTHERWISE...MID
LEVEL ENERGY MOVING INTO THE AREA FROM THE NORTHEAST COMBINED WITH
DAYTIME HEATING AND INCREASING MOISTURE WILL RESULT IN ISOLATED
SHOWERS AND THUNDERSTORMS ACROSS THE AREA TODAY. A MIX OF CLOUDS AND
SUN TODAY WITH HIGH TEMPERATURES RANGING FROM THE MID TO UPPER 80S
ALONG COAST TO AROUND 90 ELSEWHERE. PRECIPITABLE WATER VALUES BEGIN
TO INCREASE TODAY AS SURFACE HIGH PRESSURE ACROSS THE EASTERN U.S.
MOVES FARTHER EAST ALLOWING FOR DEEP TROPICAL MOISTURE TO INCREASE
ACROSS THE REGION. A WEAK COASTAL TROUGH DEVELOPS LATER TODAY ALONG
THE LOWER TEXAS COAST.

TONIGHT AND WEDNESDAY...THE WEAK CONVERGENCE ZONE ALONG THE COAST
COMBINED WITH INCREASING PRECIPITABLE WATERS SUGGEST ISOLATED
CONVECTION TONIGHT AND SCATTERED ACTIVITY FOR WEDNESDAY. OVERNIGHT
LOW TEMPERATURES TONIGHT WILL RANGE FROM THE LOWER 70S ACROSS THE
NORTHERN RANCHLANDS TO THE MID TO UPPER 70S ACROSS THE VALLEY AND
ALONG THE COAST. THE INCREASE IN RAIN CHANCES AND CLOUD COVER SHOULD
KEEP HIGH TEMPERATURES IN THE UPPER 80S TO AROUND 90.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...THE 500 MB RIDGING
WILL BE BREAKING DOWN OVER THE SOUTH CENTRAL PLAINS STATES AS A
STRONG 500 MB TROUGH DIGS SOUTH AND SOUTHWEST ACROSS THE MID
SECTION OF THE LOWER 48 STATES. A PORTION OF THIS TROUGH AXIS IS
EXPECTED TO CLOSE OFF SOMEWHERE OVER THE CENTRAL PORTION OF THE
COUNTRY. THE BIG QUESTION IS EXACTLY WHERE. THE GFS KEEPS THE
CLOSED LOW CENTERED MORE OVER THE CENTRAL PLAINS STATES WHILE THE
ECMWF WANTS TO CLOSE IT OFF SOMEWHERE OVER TX. AFTER CLOSING OFF
THIS MID LEVEL LOW BOTH OF THE MODELS THEN OPEN IT UP AND MOVE IT
OUT TO THE NORTHEAST AS ANOTHER LARGE CLOSED MID LEVEL LOW MOVES
EAST FROM THE WEST COAST TOWARDS THE CENTRAL STATES NEXT WEEKEND.

AS THE MID LEVEL TROFFING INCREASES OVER THE REGION DEEP LAYER
MOISTURE ADVECTION WILL INCREASE OVER SOUTH TX FROM THE SOUTH AND
SOUTHWEST RESULTING IN A BETTER CONV SETUP STARTING WED NIGHT AND
CONTINUING INTO THE WEEKEND. IN ADDITION TO THE 500 MB TROFFING
BOTH THE LONGER RANGE MODELS ARE INDICATING A STRONGER POTENTIAL
FOR SURFACE COASTAL TROFFING FORMING UP AND PERSISTING ALONG THE
LOWER TX COASTLINE THROUGHOUT MUCH OF THIS WEEK. THIS WILL IN TURN
PROVIDE BETTER SURFACE CONVERGENCE WHICH WILL ENHANCE THE CONV
POTENTIAL. SO CONSIDERING THE STRONGER SIGNALS INDICATED BY BOTH
THE GFS AND THE ECMWF WILL BE EDGING UP POPS A BIT ALONG THE
COASTAL AREAS FROM AROUND LATE WED THROUGH SAT. THE UPDATED
FORECAST POPS WILL BE A GENERAL BLEND OF THE ECMWF AND GFS MEX MOS
NUMBERS THROUGH DAY 7.

WILL MAINTAIN A LITTLE LOWER TEMPS THROUGH SATURDAY AS THE HIGHER
CLOUD COVER AND POP POTENTIAL WILL TEND TO HOLD THE TEMPS DOWN A
BIT. AFTER SATURDAY WILL START WARMING UP THE TEMPS A BIT AS DRIER
AIR STARTS TO FILTER INTO THE REGION. OVERALL TEMPS LEANED MORE
TOWARDS THE SLIGHTLY COOLER ECMWF NUMBERS.

OVERALL CONFIDENCE IN THE LONGER RANGE FORECAST WORDING IS A
LITTLE ABOVE AVERAGE. ON THE POSITIVE SIDE BOTH THE ECMWF AND GFS
ARE IN A LITTLE BETTER AGREEMENT IN THE DEVELOPMENT OF THE
CENTRAL U.S. MID LEVEL TROFFING LATER THIS WEEK. ON THE NEGATIVE
SIDE DIFFERENCES REMAIN BETWEEN THE MODELS IN EXACTLY WHERE THE
CLOSED LOW WILL FORM OVER THE CENTRAL STATES.

MARINE....MARINE...NOW THROUGH WEDNESDAY...BUOY 42020 CURRENTLY
REPORTING EAST WINDS OF 10 KNOTS WITH GUSTS NEAR 12 KNOTS WITH
SEAS OF 3.3 FEET. HIGH PRESSURE ACROSS THE NORTHERN GULF WILL
INTERACT WITH LOWER PRESSURE OVER THE SOUTHERN GULF. THIS WILL
RESULT IN MODERATE TO OCCASIONALLY STRONG NORTHEAST TO EAST FLOW
THROUGH THE PERIOD. EXERCISE CAUTION CONDITIONS WILL PREVAIL OVER
THE LOWER TEXAS GULF WATERS TODAY AND TONIGHT DUE TO THE INCREASE
IN WINDS AND SEAS. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
EXPECTED ACROSS THE LOWER TEXAS COASTAL WATERS TODAY THROUGH
WEDNESDAY.

WEDNESDAY NIGHT THROUGH SATURDAY...BROAD SURFACE RIDGING WILL
LIKELY PERSIST OVER THE GULF OF MEXICO THROUGH THE REST OF THIS
WEEK INTO THE WEEKEND. THIS WILL MAINTAIN A FAIRLY MODERATE AND
STEADY EAST TO NORTHEAST FLOW PATTERN OVER THE LOWER TX BAY AND
GULF WATERS. SURFACE COASTAL TROFFING DEVELOPING ALONG THE
COASTLINE LATER THIS WEEK MAY HELP MAGNIFY THE WINDS AND SEAS A
BIT. HOWEVER AT THIS TIME DO NOT EXPECT ANY SCA CONDITIONS.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  89  77  89  75 /  20  20  40  30
BROWNSVILLE          89  75  89  74 /  20  20  40  40
HARLINGEN            90  74  89  73 /  20  20  40  30
MCALLEN              89  74  90  73 /  20  20  40  30
RIO GRANDE CITY      90  73  90  72 /  20  20  40  30
SOUTH PADRE ISLAND   87  78  88  77 /  20  20  40  40

&&

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

$$

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

SHORT TERM...63
LONG TERM...60
GRAPHICAST/UPPER AIR...CAMPBELL




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