Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 011103 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
603 AM CDT WED JUL 1 2015

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

&&

.AVIATION...SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE
A MIX CLOUD OF DECKS...LOW CLOUDS NEAR THE COAST AND MID TO HIGH
LEVEL CLOUDS ACROSS THE WEST THIS MORNING. CEILINGS RANGE FROM
AROUND 4500 FEET AT MFE TO 12000 FEET AT EBG. A MIX OF VFR/MVFR
CONDITIONS WILL PREVAIL ACROSS THE REGION THIS MORNING AS CONVECTION
DEVELOPS AND MOVES INTO PORTIONS OF THE RIO GRANDE VALLEY AS A MID
LEVEL FEATURE MOVES OVERHEAD. LATEST BROWNSVILLE RADAR SHOWS
INCREASING CONVECTION SOUTH OF THE VALLEY. THIS ACTIVITY IS
EXPECTED TO IMPACT AREA AIRPORTS NOW THROUGH 16Z. CONVECTION MAY
LINGER THROUGH THE EARLY AFTERNOON HOURS AT MFE. OTHERWISE...VCSH
AND VFR CEILINGS WILL PREVAIL ACROSS DEEP SOUTH THIS AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 416 AM CDT WED JUL 1 2015/

SHORT TERM /NOW THROUGH THURSDAY/...LATEST WATER VAPOR IMAGERY
CONTINUES TO SHOW THAT THE REGION IS BETWEEN TWO 500MB RIDGES...ONE
OVER THE GREAT BASIN AND THE OTHER OVER THE EASTERN GULF OF MEXICO.
ALSO...TWO FEATURES ALOFT PREVAIL OVER DEEP SOUTH TEXAS THIS
MORNING. ONE IS A 250MB TROUGH WITH THE ASSOCIATED WEST TO NORTHWEST
FLOW IS PROVIDING SOME CIRRUS TO STREAM OVERHEAD. THE OTHER IS A
WEAK 500MB LOW/INVERTED TROUGH OVER NORTHEAST MEXICO EXTENDING INTO
DEEP SOUTH TEXAS WHICH IS BRINGING ABUNDANT LOW TO MID LEVEL
MOISTURE ACROSS THE WESTERN GULF OF MEXICO INTO THE AREA THIS
MORNING. IR SATELLITE THIS MORNING SHOWS A PLUME OF MOISTURE WITH
VERY COLD CLOUD TOPS OVER THE SOUTHWEST GULF OF MEXICO...ALONG THE
MEXICAN COAST LINE...SLOWLY MOVING NORTHWARD. BROWNSVILLE RADAR
CURRENTLY SHOWS A CLUSTER OF SHOWERS AND THUNDERSTORMS OVER THE
LOWER TEXAS GULF WATERS AND SOUTH OF THE RIO GRANDE RIVER. THIS
CONVECTION WILL CONTINUE TO MOVE TO THE NORTH-NORTHWEST AND AFFECT
MOST OF THE RIO GRANDE VALLEY THROUGH AROUND SUNRISE.

THE MAIN FORECAST ISSUE WILL BE THE COVERAGE OF POPS. THE LATEST
NAM/ECMWF/GFS ALL SUGGEST CHANCE TO LIKELY POPS FOR TODAY.
HOWEVER...THE ONGOING CONVECTION MOVING INTO THE AREA WITHIN THE
NEXT FEW HOURS MAY STABILIZE THE ATMOSPHERE. THE STABLE AIRMASS AND
ABUNDANT DEBRIS CLOUDINESS MAY LIMIT ADDITIONAL ACTIVITY LATER
TODAY. SO WILL LEAN TOWARDS THE LOWER SIDE OF THE MODEL GUIDANCE AND
KEEP POPS IN THE CHANCE CATEGORY. WITH THE DEEP TROPICAL MOISTURE IN
PLACE...PRECIPITABLE WATER VALUE OF 2.06 INCHES PER THE 0Z BRO
SOUNDING...WILL CONTINUE TO MENTION HEAVY RAINFALL IN THE GRIDS/TEXT
PRODUCTS FOR TODAY. THE INCREASE RAIN CHANCES AND CLOUD COVER WILL
KEEP HIGH TEMPERATURES TODAY GENERALLY IN THE UPPER 80S TO LOWER
90S.

RAIN CHANCES WILL DIMINISH TONIGHT WITH THE LOSS OF DAYTIME HEATING
AND AS SLIGHTLY DRIER AIR FILTERS INTO THE AREA. A FEW SHOWERS WILL
BE POSSIBLE TONIGHT INTO EARLY THURSDAY MORNING. LOW TEMPERATURES
TONIGHT WILL RANGE FROM THE MID 70S ACROSS THE NORTHERN RANCHLANDS
TO THE UPPER 70S TO AROUND 80 ALONG THE COAST. DRIER AIR BETWEEN 850
TO 650MB SHOULD ONLY SUPPORT ISOLATED CONVECTION ACROSS DEEP SOUTH
TEXAS ON THURSDAY...WHICH IS CLOSE TO THE LATEST NAM/GFS MOS
NUMBERS. LOWER RAIN CHANCES AND LESS CLOUD COVER WILL ALLOW HIGH
TEMPERATURES TO REACH THE LOW TO MID 90S THURSDAY AFTERNOON.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...500 MB LOW PRESSURE
RETROGRADING ACROSS THE BAY OF CAMPECHE WILL PRODUCE ISOLATED
SHOWERS AND THUNDERSTORMS DURING THE DAYLIGHT HOURS FROM FRIDAY
THROUGH SUNDAY. WITH THE GREATEST PRECIPITABLE WATER VALUES NEARER
THE COAST...THE CONVECTION IS LIKELY TO BE CONFINED OVER THE
CENTRAL AND EASTERN PORTIONS OF THE BRO CWFA AND ADJACENT COASTAL
WATERS. DRIER WEATHER IS ANTICIPATED FOR MONDAY AND TUESDAY AS 500
MB HIGH PRESSURE OVER THE FOUR CORNERS AREA RE-CENTERS OVER THE
TEXAS PANHANDLE AND BECOMES MORE DOMINANT OVER DEEP SOUTH TEXAS
AND THE RIO GRANDE VALLEY. INHERITED HIGH AND LOW TEMPERATURES
LOOKED REASONABLE FOR NOW AND WERE LARGELY RETAINED...BUT WITH
THE 500 MB HIGH BECOMING MORE DOMINANT EARLY NEXT WEEK...DAYTIME
HIGH TEMPERATURES MAY NEED TO BEGIN TO BE RAISED BY FUTURE SHIFTS
SOON.

MARINE...NOW THROUGH THURSDAY...LIGHT TO MODERATE SOUTH TO
SOUTHEAST WINDS PREVAIL ALONG THE LOWER TEXAS COAST THIS MORNING.
BUOY 42020 CURRENTLY REPORTING SOUTHEAST WINDS AT 18 KNOTS WITH
SEAS OF 4.3 FEET. HIGH PRESSURE OVER THE GULF WILL MAINTAIN LIGHT
TO MODERATE SOUTHEAST FLOW WITH SEAS BETWEEN 3 TO 5 FEET OVER THE
LOWER TEXAS GULF WATERS THROUGH THE FORECAST PERIOD. ABUNDANT
TROPICAL MOISTURE WILL SUPPORT A GOOD CHANCE OF SHOWERS AND
THUNDERSTORMS FOR TODAY.

THURSDAY NIGHT THROUGH TUESDAY...MODERATE WINDS AND SEAS ARE
LIKELY THROUGH THE FORECAST PERIOD WITH HIGH PRESSURE OVER THE
GULF OF MEXICO INTERACTING WITH LOW PRESSURE OVER NORTHERN MEXICO.
SMALL CRAFT WILL LIKELY NEED TO EXERCISE CAUTION FOR A PORTION OF
THE LOWER TEXAS COASTAL WATERS FROM THURSDAY NIGHT THROUGH MONDAY
NIGHT.

&&

.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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