Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 192327
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
627 PM CDT SAT JUL 19 2014

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

&&

.AVIATION...CONVECTION HAS TAPERED OFF IN THE LAST HOUR...BUT A
RECOGNIZABLE BOUNDARY STILL EXISTS OVER SOUTHEASTERN HIDALGO
COUNTY SO AT LEAST SOME ADDITIONAL DEVELOPMENT IS POSSIBLE THROUGH
THE NEXT 1 TO 2 HOURS. AFTER THAT WINDS WILL GRADUALLY BECOME MORE
UNIFORM...ALEBEIT LIGHT...OUT OF THE SOUTHEAST WITH AN MVFR CIG
DEVELOPING. LOW LEVEL MOISTURE REMAINS VERY HIGH SO AT LEAST SOME
TEMPORARY DROPS TO IFR ARE POSSIBLE ESPECIALLY AROUND SUNRISE. CIG
WILL LIFT AND SCATTER TO VFR BY MID TO LATE MORNING AMID MODERATE
SOUTHEAST WINDS ON SUNDAY. /68-JGG/

&&

.PREV DISCUSSION... /ISSUED 324 PM CDT SAT JUL 19 2014/

DISCUSSION...LOOKING CLOSELY AT NEAR TERM CONVECTIVE TRENDS
MODERATE INTENSITY THUNDERSTORMS...WHICH APPEAR TO BE CLOSELY
ASSOCIATED WITH 850MB FRONTOGENETIC FORCING FROM INCREASED 850MB
SOUTHEASTERLIES ARE MEANDERING NORTH ACROSS THE RANCHLANDS.
FURTHER SOUTH IN THE VALLEY AN OUTFLOW BOUNDARY GENERATED BY THIS
CONVECTION IS GENERATING SPOTTY SHOWERS.

OF NOTE THROUGH THE NEXT 3 TO 5 HOURS IS EXTREME
INSTABILITY...WITH MIXED LAYER CAPE VALUES OF AROUND 3500 TO 4000
J/KG OVER THE RGV METRO AREAS AND LAYER PRECIPITABLE WATER VALUES
OF 2.2 INCHES. SFC-700MB THETA E DIFFERENTIALS OF 30 TO 35 C ARE
ALSO ANALYZED ON LAPS/MODIFIED OBSERVED AND NAM12 SOUNDINGS. SHEAR
IS QUITE LOW AND ANY UPDRAFTS THAT DO GO UP WILL LIKELY BE SHORT
LIVED...BUT COULD BE QUITE INTENSE.

THROUGH ABOUT 800 PM CDT WILL BE MONITORING CLOSELY FOR
DEVELOPMENT ALONG THIS OUTFLOW BOUNDARY AND ANY STRONGER CELLS
THAT FORM WILL ALMOST CERTAINLY PRODUCE TORRENTIAL
RAINS...POSSIBLY LEADING TO URBAN AREA FLOODING...AND WILL ALSO
POSE AN ATTENDANT WET MICROBURST POTENTIAL WITH SEVERE MICROBUSRTS
NOT TOTALLY OUT OF THE QUESTION. /68-JGG/

PREV DISCUSSION... /ISSUED 227 PM CDT SAT JUL 19 2014/

SHORT TERM /NOW THROUGH SUNDAY NIGHT/...SHOWERS AND TSTMS
CONTINUE TO PROGRESS NORTHWARD ACROSS THE GREATER RANCH LANDS TO
THE NORTH. A WEAK OUTFLOW BOUNDARY REMAINS NEARLY STATIONARY
ACROSS WILLACY AND HIDALGO COUNTIES...WHICH COULD PROVIDE THE
FOCUS FOR ANOTHER ROUND OF CONVECTION SIMILAR TO YESTERDAY
EVENING. SOUTHERLY WINDS WILL PUSH THE DENSER PLUME OF MOISTURE
NORTHWARD TONIGHT...WITH PW VALUES FALLING BELOW NORMAL AT 1.5 TO
1.6 INCHES BY SUNDAY MORNING. WITH THE LOSS OF MOISTURE TO FUEL
SHOWERS...POP CHANCES WILL END FOR THE VALLEY...WITH SKIES PARTLY
TO MOSTLY SUNNY. WITH LESS CLOUDS...TEMPERATURES WILL AGAIN SOAR
INTO THE UPPER 90S TO LOW 100S...WITH HEAT INDEX VALUES 105 TO
110.

LONG TERM /MONDAY THROUGH FRIDAY/...THE LONG TERM LOOKS RATHER
QUIET OVERALL. WE START OUT WITH MID LEVEL RIDGING SLOWLY BUILDING
OVER NEW MEXICO THROUGH TUESDAY...WITH A POSITIVE TILT TROUGH OVER
THE SOUTHEAST UNITED STATES. LOW PRESSURE OVER THE BAY OF CAMPECHE
AND ONGOING UNSETTLED WEATHER OVER THE MEXICAN MOUNTAINS WILL ROUND
OUT THE INITIAL CONDITIONS. WHILE THE RIDGE BUILDS OVER NEW MEXICO
AND WEST TEXAS INTO TUESDAY...A BUBBLE LOW WILL BREAK OFF FROM THE
TROUGH OVER THE NORTHERN GULF COAST OVER MOBILE. MOVEMENT WILL BE
SLOW...BUT THE FEATURE WILL DRIFT WEST UNDER THE RIDGE TOWARD THE
NORTHWEST GULF THROUGH WEDNESDAY. THIS MAY BRING A FEW SHOWERS OR
THUNDERSTORMS TO THE OFFSHORE MARINE AREAS. FURTHER MOVEMENT OVER
HEAD WEDNESDAY NIGHT AND THURSDAY MAY PRODUCE A LIMITED CHANCE OF
PRECIPITATION...ABOUT THE ONLY CHANCE IN THE LONG TERM. AFTER THAT
RIDGING WILL TEND TO BUILD BACK OVERHEAD FROM THE NORTH AND NORTH
WEST. TEMPERATURES WILL TEND TO RUN ABOVE NORMAL THROUGH THE LONG
TERM...MORE SO AT NIGHT HOWEVER. THIS WILL BE FORCED BY ELEVATED DEW
POINTS...WHICH WILL ALSO PRODUCE DAILY INLAND AFTERNOON HEAT INDEX
VALUES FROM ABOUT 104 TO 108...ON AVERAGE. MODERATE ONSHORE FLOW
WILL PREVAIL WITH A MIX OF CLOUDS AND SUN...MORE SUN EARLIER IN THE
WEEK WITH A FEW MORE CLOUDS BEGINNING AROUND MID WEEK.

MARINE...
NOW THROUGH SUNDAY NIGHT...LIGHT WINDS WILL CONTINUE FOR THE
MARINE ZONES TONIGHT AS WEAK GRADIENT CONTINUES TO AFFECT THE NW
GULF. THE LONGER FETCH ACROSS THE GULF HAS CONTINUED TO BRING
LONGER PERIOD SWELLS ACROSS THE GULF WATERS...VARYING BETWEEN 3
AND 4 FEET WITH A 7 TO 8 SECOND PERIOD. WINDS MAY PICK UP SOME
SUNDAY AFTERNOON FOR THE LAGUNA MADRE AS LOW PRESSURE INCREASES IN
FAR WEST TEXAS...BUT WINDS SHOULD REMAIN AROUND 15 KNOTS. LONG
FETCH SWELLS CONTINUE FOR THE GULF...RUNNING AROUND 3 OR 4 FEET
WITH A LONGER PERIOD.

MONDAY THROUGH WEDNESDAY...MID LEVEL RIDGING WILL BUILD OVER NEW
MEXICO AND WEST TEXAS...WITH BROAD HIGH PRESSURE CONTINUING OVER THE
WEST GULF. THE RESULT WILL BE LIGHT TO MODERATE SOUTH SOUTHEAST
WINDS AND MODERATE SEAS. A LOWER HEIGHT CENTER WILL BUBBLE OFF FROM
THE MID LEVEL TROUGH OVER THE SOUTHEAST UNITED STATES EARLY IN THE
WEEK...AND WILL DRIFT WEST ACROSS THE NORTH GULF THROUGH THE MIDDLE
OF THE WEEK AND THEN OVER AND THROUGH SOUTH TEXAS LATE IN THE WEEK.
THIS FEATURE MAY PROVIDE ENOUGH INSTABILITY TO TRIGGER A FEW SHOWERS
AND THUNDERSTORMS ACROSS THE LOWER TEXAS COASTAL WATERS AROUND MID
WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  81  93  81  94 /  30  10  10   0
BROWNSVILLE          80  94  79  95 /  30  10  10   0
HARLINGEN            79  98  79  98 /  30  10  10   0
MCALLEN              80 100  79 100 /  30  10  10   0
RIO GRANDE CITY      80  99  79 100 /  20  10  10   0
SOUTH PADRE ISLAND   80  90  80  91 /  30  10  10  10

&&

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

$$

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

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