Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 101745 AAC
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1245 PM CDT THU JUL 10 2014

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

.AVIATION...SATELLITE AND RADAR IMAGES AS WELL AS SURFACE
OBSERVATIONS CONTINUE TO INDICATE CONVECTION ACROSS THE SOUTHERN
AND EASTERN PORTIONS OF THE CWA MOVING NORTHWARD THIS AFTERNOON.
CEILINGS WERE NEAR 2400FT AT KHRL TO NEAR 10000FT AT KHBV.
VISIBILITIES WERE NEAR 3SM WITH LIGHT RAIN AND MIST AT KPIL TO
NEAR 5SM WITH LIGHT RAIN AND MIST AT KHRL. EXPECT MVFR CONDITIONS
TO CONTINUE THE REST OF THE AFTERNOON WITH SHOWERS AND ISOLATED
THUNDERSTORMS MOVING ACROSS THE NORTHERN PORTIONS OF THE CWA.
OTHERWISE...VFR CONDITIONS SHOULD PREVAIL THE REST OF THE
AFTERNOON INTO THE EVENING ACROSS THE REST OF THE CWA AS THE
ATMOSPHERE STABILIZES IN THE WAKE OF THE CONVECTION LIFTING
NORTHWARD ACROSS THE AREA.
&&

.PREV DISCUSSION... /ISSUED 923 AM CDT THU JUL 10 2014/
DISCUSSION...SATELLITE AND RADAR IMAGES INDICATE CONVECTIVE BURST
CONTINUES TO DEVELOP ACROSS NORTHERN TAMAULIPAS WHILE THE
CONVECTION THAT MOVED THROUGH THE COASTAL WATERS EARLIER THIS
MORNING CONTINUES TO LIFT NORTHWARD TOWARDS THE COASTAL BEND. WILL
GO AHEAD AND INCREASE POPS THIS MORNING AND AFTERNOON...MAINLY
ACROSS THE SOUTHERN AND WESTERN PORTIONS OF THE CWA...WHERE
CONVERGENCE AND MOISTURE APPEARS TO BE INCREASING. ALSO...WILL
MENTION HEAVY RAINFALL WITH THUNDERSTORMS TODAY AS RADAR ESTIMATES
ISOLATED RAINFALL RATES OF 2 TO 3 INCHES PER HOUR ACROSS NORTHEAST
MEXICO THIS MORNING.

PREV DISCUSSION... /ISSUED 602 AM CDT THU JUL 10 2014/
DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...THE CONVECTIVE THREAT FOR AVIATION INTERESTS WILL
DEFINITELY BE HIGHER TODAY...DUE TO TROPICAL SHOWERS/TSTMS MOVING
UP FROM THE SOUTH. LACK OF STRONG MARINE LAYER/INVERSION MAY
PRECLUDE EXCESSIVE LOW CLOUDS FOR NOW...WITH CEILINGS REMAINING
VFR EXCEPT IN ANY HEAVIER CONVECTION. ONE CLUSTER OF CONVECTION
MOVED NORTH EARLIER...BUT STAYED MAINLY OFFSHORE. EXPECT ANOTHER
ROUND LATER THIS MORNING AND MAYBE ANOTHER THIS AFTN. CONVECTION
WILL EVENTUALLY SHIFT INLAND LATER IN THE DAY HOWEVER. THE EXACT
TIMING OF CONVECTIVE BANDS COULD BE A BIT UNCERTAIN DEPENDING ON
THE STRENGTH OF NORTHWARD MOVING BOUNDARIES. BRO AIRPORT OPS
SHOULD BE PREPARED FOR AN AWW IF THUNDERSTORMS DEVELOP NEAR THE
FIELD. CONVECTION CHANCES SHOULD DECREASE THIS EVENING AND WILL
BE OF MUCH LESSER CONCERN ON FRIDAY. LIGHT TO MODERATE SOUTHEAST
WINDS WILL PREVAIL EXCEPT IF/WHEN DISRUPTED BY CONVECTIVE GUSTS
WHICH COULD BE UP TO 30 OR 35 MPH.

PREV DISCUSSION... /ISSUED 320 AM CDT THU JUL 10 2014/

SHORT TERM /TODAY THROUGH FRIDAY/...MODELS ARE IN AGREEMENT WITH
TURNING THE SPIGOT UP A NOTCH ON POPS FOR TODAY. INSTABILITY OVER
THE EAST AND NORTHEAST MEXICAN COAST WILL SUPPORT TROPICAL SHOWERS
AND THUNDERSTORMS TODAY...WHICH WILL MOVE NORTH INTO AND OVER DEEP
SOUTH TEXAS AND THE RGV...BUT ESPECIALLY THE COASTAL AREAS. PWAT AT
BRO IS PROGGED TO SPIKE UP TO TWO INCHES AND A QUARTER TODAY BEFORE
SETTLING BACK DOWN TO AN INCH AND A HALF ON FRIDAY. THE LATEST BATCH
OF CONVECTION IS MOVING THROUGH THE AREA EARLY THIS MORNING AND WILL
PASS ON TO THE NORTH...BUT ANOTHER CLUSTER OR TWO OF ACTIVITY IS
VISIBLE ON SATELLITE IMAGERY FROM 200 TO 250 MILES TO THE SOUTH. IT
IS NOT ENTIRELY CLEAR TO WHAT EXTENT THE HEAVIEST OF THE NEW
ACTIVITY WILL MOVE NORTH...AND MODEL GUIDANCE GRADUALLY TAPERS
OVERALL POPS DOWN THROUGH THE SHORT TERM...BUT SMALLER AREAS OF
ACTIVITY WILL LIKELY DEVELOP AND MOVE UP ON A REGULAR BASIS THROUGH
TONIGHT. THUS...BUMPED COASTAL AND MID VALLEY POPS UP TO 50 PERCENT
FOR TODAY...TAPERING OFF GRADUALLY THIS AFTERNOON AND TONIGHT. IF
COVERAGE PERSISTS HOWEVER...LIKE INTO THIS AFTERNOON AND OVER THE
PLAINS SOUTH OF THE RIVER...QUICK UPGRADES WILL NOT BE DIFFICULT.
MOSTLY CLOUDY SKIES WILL HOLD HIGH TEMPS DOWN TODAY...AND THE
CURRENT FORECAST HIGHS...MAINLY IN THE UPPER 80S...WILL BE A BIT
BELOW NORMAL AS A RESULT. LOWS TONIGHT WILL REPEAT IN THE MID 70S.
AS MENTIONED PREVIOUSLY...LIFT WILL SHIFT INLAND ON FRIDAY WITH
LESSER CHANCES FOR RAIN OVERALL...WITH HIGH TEMPS RECOVERING A FEW
DEGREES TO NEAR NORMAL.

LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
LITTLE CHANGE IN THE LONG TERM REASONING TONIGHT. GFS/ECMWF CONTINUE
TO MOVE THE MID LEVEL WEAKNESS THAT HAS BEEN PARKED OVER THE REGION
FOR SEVERAL DAYS TO THE EAST AND OUT OF THE PICTURE BY FRIDAY
EVENING. MID AND LOW LEVEL RIDGING TAKE ITS PLACE...BUT THE OVERALL
INTENSITY IS NOT ESPECIALLY LARGE AND AT LEAST EARLY IN THE LONG
TERM PERIOD THE UPPER LEVEL FLOW IS WEAK...WHICH PREVENTS LEE
TROUGHING TO THE WEST...AND THE LONGER WAVE TROUGHS ARE ALL WELL TO
THE NORTH.

THE RESULT IS A RELATIVELY LIGHT SYNOPTIC SCALE WIND PATTERN...WITH
MODERATE GENERALLY SOUTHEAST WINDS. THIS TRAJECTORY WILL ADVECT IN
PREVIOUSLY SUBSIDED MID AND LOWER LEVEL AIR...WHICH IN CONCERT WITH
LARGE SCALE SUBSIDENCE WILL CONTINUE TO DRY THE COLUMN SIGNIFICANTLY
THROUGH THE PERIOD. LOCKING US INTO A HOT AND DRY PATTERN FOR
SEVERAL DAYS.

THIS REMAINS THE CASE UNTIL PERHAPS WEDNESDAY OR THURSDAY WHEN
TROUGHING BEGINS TO DIG INTO THE CENTRAL PLAINS AND OUR LOW LEVEL
GRADIENT INCREASES WITH SOUTHWEST WINDS BECOMING GUSTIER. THERE ARE
ALSO INDICATIONS OF AN EASTERLY WAVE MOVING CLOSER TO THE AREA BY
THURSDAY/FRIDAY BUT RIGHT NOW ANY INFLUENCE APPEARS WEAK AND JUST
OUTSIDE THE SCOPE OF THE CURRENT FORECAST SO KEPT THE OUTLOOK DRY
AND HOT.

MARINE...
TODAY THROUGH FRIDAY...1015 TO 1020 MB HIGH PRESSURE UNDER MID LEVEL
RIDGING WILL CONTINUE TO EXTEND OVER THE NORTH GULF...RESULTING IN A
GENERAL ANTICYCLONIC FLOW PATTERN. LIGHT TO MODERATE SOUTHEAST WINDS
AND LOW TO MODERATE SEAS WILL CONTINUE IN THE SHORT TERM. UNSETTLED
WEATHER WILL PREVAIL ALONG THE NORTHEAST COAST OF MEXICO TODAY AND
TONIGHT AS A MID LEVEL WEAKNESS AND DIFFLUENT FLOW ALOFT PROVIDE A
FAVORABLE ENVIRONMENT FOR CONVECTION. SHOWERS AND THUNDERSTORMS WILL
TEND TO MOVE NORTH INTO THE LOWER TEXAS COASTAL WATERS AND COASTAL
COUNTIES.

FRIDAY NIGHT THROUGH TUESDAY...
GENERALLY FAVORABLE MARINE CONDITIONS ARE FORECAST THROUGH THIS
TIME FRAME. SOUTHEASTERLY WINDS SHOULD BE LIGHT TO MODERATE WITH LOW
TO MODERATE SEAS. RAIN AND THUNDERSTORM CHANCES ALSO APPEAR LOW.
&&

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

$$

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