Area Forecast Discussion
Issued by NWS Brownsville, TX

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934
FXUS64 KBRO 220908
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
408 AM CDT FRI MAY 22 2015

.SHORT TERM.../TODAY THROUGH SATURDAY/...

...THREAT OF LOCALIZED FLASH FLOODING CONTINUES ACROSS MOST OF
DEEP SOUTH TEXAS TODAY...

SATELLITE AND RADAR IMAGES CONTINUE TO INDICATE THE MCS ACROSS
THE MEXICAN PLATEAU CONTINUES TO WEAKEN AS IT MOVES EASTWARD.
HOWEVER...ISOLATED CONVECTION HAS BEGUN TO DEVELOP ACROSS
NORTHEAST MEXICO INTO EXTREME WESTERN PORTIONS OF THE RIO GRANDE
VALLEY EARLY THIS MORNING. IN ADDITION...ISOLATED TO SCATTERED
CONVECTION CONTINUES TO DEVELOP OFFSHORE THE LOWER TEXAS COAST AND
MOVE TOWARDS THE COASTAL BEND. WITH A WEAK STATIONARY FRONTAL
BOUNDARY DRAPED ACROSS THE NORTHERN RANCHLANDS THIS MORNING...LOW
TO MID LEVEL MOISTURE WILL CONTINUE TO POOL ACROSS THE CWA TODAY
AND THE BOUNDARY SHOULD PROVIDE A FOCUS FOR LOW LEVEL CONVERGENCE.
SHOWERS AND THUNDERSTORMS WILL LIKELY DEVELOP ALONG THE FRONTAL
BOUNDARY THIS AFTERNOON AND WITH PRECIPITABLE WATER VALUES NEAR
1.85 INCHES AS WELL AS WEAK STORM RELATIVE WINDS...THE POTENTIAL
FOR LOCALIZED FLASH FLOODING CONTINUES THROUGH THIS AFTERNOON.
WILL EXTEND FFA THROUGH 6 PM TODAY AND CONTINUE TO MENTION HEAVY
RAINFALL WITH STORMS TODAY.

WITH THE LOSS OF DIURNAL HEATING TONIGHT AND THE FRONTAL BOUNDARY
WASHING OUT AS A MORE SOUTHERLY FLOW DEVELOPS ACROSS THE RIO GRANDE
VALLEY...SHOWERS AND THUNDERSTORMS WILL DIMINISH IN COVERAGE THIS
EVENING BUT WILL MENTION A SLIGHT CHANCE OF RAIN THROUGH TONIGHT.
RAIN CHANCES WILL INCREASE SATURDAY AS THE 500MB LOW/TROUGH ACROSS
SOUTHERN CA/BAJA CA MOVES INTO THE SOUTHWEST UNITED STATES
SATURDAY...BUT MOST OF THE CONVECTION SHOULD BE MOSTLY NORTH OF THE
AREA. WILL GO WITH A CHANCE OF SHOWERS AND THUNDERSTORMS FOR MOST OF
THE CWA FOR NOW.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY..UPPER LEVEL LOW ENTERING
THE CA COAST IN THE SHORT TERM WILL PROGRESS SLOWLY EAST ACROSS THE
DESERT SOUTHWEST WITH A SERIES OF WAVES MOVING WITHIN THE FLOW BEFORE
LIFTING NORTHEAST INTO THE CENTRAL PLAINS. THIS SYSTEM WILL RESPONSIBLE
FOR THE ACTIVE WEATHER PATTERN DURING THE EARLY PORTION OF THE LONG
TERM PERIOD. THE SYSTEM WILL WEAKEN AS IT MOVES FURTHER EAST WITH RIDGE
BUILDING WEDNESDAY INTO THURSDAY LIMITING THE CHANCE OF RAIN TO AROUND
20 PERCENT OR LESS.

ANOTHER JET MAX WILL DIG FURTHER SOUTHEAST THE UPPER LEVEL TROUGH WHICH
PUTS THE CWA UNDER A GOOD AREA OF DIFFLUENCE FLOW ALOFT WITH ANOTHER
ROUND OF UPPER LEVEL WAVE TO SUPPORT FOR AN MCS TO DEVELOP OVER THE SIERRA
MADRE AND TRACK EAST/NORTHEAST. THE AREAS WITH HIGHER CHANCE OF BEING
IMPACTED INCLUDE THE NORTHERN RANCHLANDS AND WESTERN COUNTIES. CAN NOT
RULED OUT THAT SOME CONVECTION WILL DEVELOP AHEAD OF THIS ACTIVITY AND
INCREASE THE POTENTIAL FOR CONVECTION IN THE LOWER RGV THROUGH SUNDAY
AFTERNOON. DUE TO THE CONVECTION...OVERCAST CONDITIONS ARE EXPECTED WHICH
WILL MAINTAIN TEMPERATURES IN THE MID TO UPPER 80S ACROSS MUCH OF THE RGV.
DUE TO PREVIOUS HEAVY RAINFALL ALREADY RECEIVED ACROSS THE AREA...EXPECT
A POSSIBLE EXTENSION OF THE FLASH FLOOD WATCH. SOILS ACROSS THE CWA ARE
WELL OVER SATURATED WITH MANY AREAS WITH STANDING WATER. THIS WILL INCREASE
THE POTENTIAL FOR HIGHER FLOODING ACROSS THE CWA.

THE MAIN TROUGH SPEEDS UP AND BEGINS TO LIFT NORTHEAST ACROSS THE CENTRAL
PLAINS INTO EARLY NEXT WEEK AND WITH IT PUSHING NORTH THE PLUME OF RICH
MOISTURE. THE TAIL END WILL STILL EXTEND ALONG THE TEXAS COAST LINE INTO
SOUTH TEXAS ENHANCING MORE CONVECTION INTO MONDAY. THE SOUTHEASTERLY FLOW
PREVAILS AS BROAD HIGH PRESSURE TAKES CONTROL OF MOST OF THE EAST AND SE
COAST OF THE CONUS. THIS WILL KEEP A SOUTHEASTERLY FLOW ACROSS THE AREA
WITH THE SURGE OF LOW LEVEL MOISTURE CONTINUING. HOWEVER...RH LEVELS WILL
BE MUCH LESS COMPARED TO EARLY IN THE WEEK LIMITING HEAVY RAINFALL BUT A
FEW ISOLATED SHOWERS WILL STILL BE POSSIBLE UNDER A HUMID AND SULTRY DAY.

NEXT TROUGH WILL BRING DRY AIR MASS INTO THE AREA DRYING OUT CONDITIONS
AND BRINGING MORE SUNSHINE ACROSS THE CWA TUESDAY INTO WEDNESDAY. THE
GFS CONTINUES TO DRY CONDITIONS A LOT FASTER THAN THE ECMWF. DUE TO
THE INCONSISTENCY BETWEEN THE MODELS AND KEEPING IN CONSIDERATION THAT
THE VALLEY HAS BEEN IN A WET PATTERN...LEAN TOWARDS THE WET ECMWF WITH
A SLIGHT RISK OF RAIN FOR NOW. TEMPERATURES DUE TO BREAK IN CLOUDS HIGHS
WILL GRADUALLY RISE BACK TO THE MID 90S.

&&

.MARINE...TODAY THROUGH SATURDAY...SEAS WERE NEAR 3 FEET WITH EAST-
SOUTHEAST WINDS NEAR 14 KNOTS AT BUOY020 EARLY THIS MORNING.
LIGHT TO MODERATE SOUTHEAST WINDS WILL PREVAIL ACROSS THE COASTAL
WATERS TODAY AS A WEAK STATIONARY FRONTAL BOUNDARY DRAPED ACROSS
THE COASTAL BEND CONTINUES TO PROVIDE A WEAK PRESSURE GRADIENT
ACROSS THE WESTERN GULF OF MEXICO. THE PRESSURE GRADIENT IS
EXPECTED TO INCREASE TONIGHT AND MODERATE TO STRONG SOUTHEAST
WINDS WILL DEVELOP ACROSS THE LOWER TEXAS COAST. SMALL CRAFT
ADVISORIES MAY BE NEEDED FOR THE OFFSHORE WATERS TONIGHT. THE
PRESSURE GRADIENT WILL REMAIN STRONG SATURDAY WITH HIGH PRESSURE
ALONG THE EASTERN U.S. COAST AND LOW PRESSURE ALONG THE LEE SIDE
OF THE ROCKIES. MODERATE TO STRONG SOUTHEAST WINDS WILL PREVAIL
ACROSS THE LOWER TX COASTAL WATERS SATURDAY AND SMALL CRAFT
ADVISORIES WILL LIKELY BE NEEDED FOR THE LAGUNA MADRE AS WELL AS
THE OFFSHORE WATERS AS A RESULT.

SATURDAY NIGHT THROUGH FRIDAY NIGHT...AS THE TROUGH LIFTS SLOWLY
NE OVER THE DESERT SW AND CENTRAL PLAINS THE PRESSURE GRADIENT
WILL REMAIN STRONG ALONG THE GULF WATERS BUILDING SEAS AND
INCREASING WINDS THROUGH THE WEEKEND. SCA ARE POSSIBLE FROM
SATURDAY NIGHT THROUGH MONDAY AS THE DISTURBANCE MOVES FURTHER NE.
A BROAD AREA OF HIGH PRESSURE WILL DOMINATE THE EAST COAST AND THE
SE PLAINS WITH A BROAD SE RETURN FLOW DOMINATING INTO THE GULF OF
MEXICO. THIS WILL KEEP SE WINDS A BIT BREEZY MONDAY INTO TUESDAY
BUT AS THE GRADIENT WEAKENS SO WILL THE WINDS RETURNING TO AROUND
15 KNOTS. SEAS RETURN TO 5 FEET WITH A LOWERING OF THE WINDS BY
WEDNESDAY INTO THURSDAY AND REMAIN AROUND THAT WAY THROUGH SUNDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  87  77  88  78 /  30  20  20  40
BROWNSVILLE          89  75  88  77 /  30  20  20  40
HARLINGEN            90  75  91  77 /  40  20  20  50
MCALLEN              92  75  92  76 /  40  20  30  40
RIO GRANDE CITY      90  75  93  75 /  40  20  30  60
SOUTH PADRE ISLAND   84  78  85  79 /  30  20  20  30

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...FLASH FLOOD WATCH THROUGH THIS AFTERNOON FOR TXZ248>250-252-253.

GM...NONE.
&&

$$

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