Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 282001
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
301 PM CDT THU APR 28 2016

.SHORT TERM  /TONIGHT THROUGH FRIDAY NIGHT/...A 500 MB CLOSED LOW
JUST WEST OF THE FOUR CORNERS WILL MOVE EAST ACROSS THE DESERT
SOUTHWEST TONIGHT...PUSHING INTO THE SOUTHERN HIGH PLAINS BY
FRIDAY. THE APPROACH OF THE LOW WILL BE ASSOCIATED WITH A SURFACE
COLD FRONTAL SYSTEM MOVING INTO WEST TEXAS TONIGHT AND FRIDAY.
THAT DEVELOPMENT WILL TIGHTEN UP THE SURFACE PGF...INCREASING SE-S
WINDS TO MODERATE OR BREEZY FROM THE COAST TO THE MID VALLEY ON
FRIDAY

PERSISTENT SE-S LOW LEVEL FLOW COMBINED WITH 500 MB RIDGING THAT
WILL BUILD OVER THE GULF OF MEXICO...AND SUBSIDENT SOUTHWEST FLOW
ALOFT WILL MAINTAIN HIGH TEMPS WELL ABOVE CLIMO FOR LATE APRIL. A
DAY IN THE 90S WEST OF I-69E WILL BE ON TAP FRIDAY...WHEN NORMALS
ARE ONLY IN THE 80S.

DEEP LAYER MOISTURE OVER THE RGV AHEAD OF THIS NEXT 500 MB CLOSED
LOW WILL REMAIN LIMITED WITH ONLY MARGINAL MOISTURE RETURN LATE
TONIGHT INTO FRIDAY. CONSIDERING THE COMBINATION OF THE FAR
NORTHWARD TRACK OF THE CLOSED MID LEVEL LOW AND THE LIMITED MOISTURE
VALUES THROUGH THE SHORT TERM...WILL GO WITH RAIN CHANCES BELOW
MENTIONABLE.

A STABLE LOW LEVEL PROFILE AND MODERATE ONSHORE WINDS WILL SUPPORT
BKN TO OVC LOW LEVEL CLOUDS TONIGHT AND FRIDAY NIGHT...AND WILL ALSO
TRAP HAZE FROM AGRICULTURAL BURNING TO THE SOUTH...REDUCING VSBY
SLIGHTLY. OVERNIGHT LOWS THE NEXT COUPLE OF NIGHTS WILL BE IN THE
70S...HIGHER THAN THE NORMALS IN THE UPPER 60S.

THE LATEST TEXAS COMMISSION ON ENVIRONMENTAL QUALITY`S (TCEQ`S) AIR
QUALITY INDEX (AQI) PLACES THE RGV IN THE CATEGORY OF "UNHEALTHY FOR
SENSITIVE GROUPS" DUE TO THE ONGOING AGRICULTURAL FIRES BURNING
ACROSS MUCH OF MEXICO AND CENTRAL AMERICA. THE SE-S LOW LEVEL FLOW
PATTERN WILL PERSIST THROUGH FRIDAY AND INTO SATURDAY...WITH LIGHTER
WINDS OVER THE WEEKEND...PUSHING SMOKE AND HAZE OVER THE RGV AND
DEGRADING AIR QUALITY. WILL MAINTAIN THE MENTION OF HAZE TONIGHT
THROUGH FRIDAY NIGHT. HAZE WILL MIX WITH SEA AIR AT NIGHT...AS FOG
FORMATION TAKES PLACE DUE TO THE LOWER TEMP/DEWPOINT SPREAD.


.LONG TERM /SATURDAY THROUGH THURSDAY/....A SERIES OF UPPER LEVEL
SYSTEMS WILL TRAVEL ACROSS THE WESTERN CONUS INTO THE CENTRAL
PLAINS DURING THE LONG TERM PERIOD. THE SYSTEM OVER THE FOUR
CORNERS WILL PUSH A COLD FRONT ACROSS OUR AREA SATURDAY ENHANCING
CONVECTION OVER THE AREA. PRECIPITABLE WATER VALUES INCREASE TO
ABOVE 1.5 TO 1.7 INCHES ON THE NAM/GFS SOUNDINGS SHOWING AN
INCREASE OF MOISTURE AT LEAST UP TO 850MB OVER THE REGION. THE
BEST CHANCE WILL BE FOCUS OVER THE NORTHERN COUNTIES AND MID
VALLEY BUT LESS OF A CHANCE IN THE LOWER VALLEY. AS THE MAIN LOW
PRESSURE WEAKENS AND LIFTS NE...THE SOUTHWEST FLOW ALOFT RETURNS
WITH DRY AIR IN THE MID LAYERS MAKING ITS WAY INTO THE CWA WHILE
EASTERLY FLOW WILL STILL REMAIN IN THE LOWER LAYERS. LOW LEVEL
MOISTURE WILL STILL BE HIGH BELOW 850 MB AVERAGE OF 70 TO 80
PERCENT WHICH COULD INITIATE A FEW SHOWERS SUNDAY AFTERNOON. DRY
LINE WILL BEGIN TO SET UP ALONG THE CONTINENTAL DIVIDE AND SIERRA
MADRE OVER MX ENHANCING THUNDERSTORM ACTIVITY INTO NEXT WEEK. THE
POTENTIAL FOR RAIN WILL INCREASE MON OVER S TEXAS AS A
PERTURBATION MOVES ACROSS THE REGION. ONCE AGAIN WED ANOTHER
INFLUX OF MOISTURE OVER MEXICO WILL TRAVEL EAST ENHANCING
CONVECTION ACROSS THE CWA.

MODELS DIFFER INTO EARLY NEXT WEEK WITH THE ARRIVAL OF THE COLD
FRONT. GFS 12Z MODEL RUN SHOWS A DELAY WITH THE FRONT WHILE THE
ECMWF IS MORE PROGRESSIVE. EVENTHOUGH THERE ARE SOME DIFFERENCES...
ABUNDANT MOISTURE WILL BE AVAILABLE AHEAD OF THE FRONT WHICH WILL
ENHANCE THE CONVECTION ACROSS THE CWA FROM MON THROUGH MID WEEK
WITH DRY AIR MOVING IN.

&&

.MARINE...NOW THROUGH FRIDAY NIGHT...HIGH PRESSURE OVER THE GULF
WILL INTERACT WITH PRESSURE FALLS OVER THE SOUTHERN HIGH PLAINS...
RESULTING IN HIGHER WINDS AND SEAS THROUGH FRIDAY NIGHT. SMALL
CRAFT ADVISORY CONDITIONS WILL BE POSSIBLE TOMORROW...FRIDAY...WITH
MORNING WINDS IN THE 20 TO 25 KT RANGE. WINDS WILL DECREASE FRIDAY
NIGHT...BUT WAVE HEIGHTS ON THE GULF MAY REMAIN SEVEN FEET OR
ABOVE THROUGH THE NIGHT.

SATURDAY THROUGH THURSDAY...A FRONT WILL MOVE THROUGH THE LOWER
TEXAS COAST SATURDAY ENHANCING SHOWERS AND THUNDERSTORMS ACROSS THE GULF
WATERS. EXPECT SEAS GRADUALLY LOWERING TO 5 TO 6 FEET AS THE GRADIENT
WEAKENS. THE FRONT WILL BE WEAK ENOUGH THAT WINDS WILL BE MORE EASTERLY
TO SE. SCEC CONDITIONS IS POSSIBLE FOR THE EARLY PORTION OF SATURDAY.
THE WINDS AND SEAS WILL REMAIN MODERATE THROUGH THE REST OF THE WEEK WITH
A WEAK GRADIENT ACROSS THE AREA. A MOISTURE INFLUX AHEAD OF THE NEXT FRONT
MONDAY WILL ENHANCE ANOTHER ROUND OF CONVECTION THROUGH WEDNESDAY BUT
MODEL DIFFERENCES CONTINUE IN THE MODEL GUIDANCE.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  77  88  77  89 /  10  10  10  20
BROWNSVILLE          78  89  78  90 /  10  10  10  20
HARLINGEN            78  92  77  94 /  10  10  10  20
MCALLEN              77  95  77  96 /  10  10  10  20
RIO GRANDE CITY      77  98  76  97 /  10  10  10  20
SOUTH PADRE ISLAND   77  84  77  83 /  10  10  10  20

&&

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

$$

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