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000
FXUS64 KBRO 090320 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
920 PM CST SUN DEC 8 2013

.DISCUSSION...A COUPLE OF FORECAST CHANGES FOR TONIGHT WERE MADE.
FIRST...ASOS AND AWOS OBSERVATIONS INDICATE WIDESPREAD FOG HAS
DEVELOPED AND IS PERSISTING WITHIN THE BRO CWFA...THEREFORE FOG WAS
ADDED FOR THE REMAINDER OF THE OVERNIGHT HOURS AND INTO TOMORROW
MORNING. SECOND...ASOS AND AWOS OBSERVATIONS ALSO INDICATE THAT
FORECAST LOW TEMPERATURES FOR TONIGHT OVER THE NORTHERN HALF OF
THE BRO CWFA WERE TOO COLD...WHILE TEMPERATURES IN THE SOUTHERN
HALF WERE TOO WARM...ALL BASED ON TRENDS AND DEWPOINTS...AND
CHANGES WERE MADE ACCORDINGLY. NO OTHER SHORT TERM FORECAST
ADJUSTMENTS NEEDED OR MADE.
&&

.PREV DISCUSSION... /ISSUED 532 PM CST SUN DEC 8 2013/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...PURE VFR WILL BE DIFFICULT TO FIND THROUGH THE NEXT
24 HOURS. LOW CEILINGS WILL LIKELY VARY IN HEIGHT TONIGHT AND
THROUGH MONDAY...AND CONFIDENCE IN THE EXACT ALTITUDE OF CLOUD
BASES IS LOW. HOWEVER...RECENT TRENDS IN CLOUD HEIGHTS SHOULD
HOLD THROUGH TONIGHT AND TOMORROW. NORTH TO NORTHWEST WINDS WILL
ALSO PERSIST.

PREV DISCUSSION... /ISSUED 254 PM CST SUN DEC 8 2013/

SHORT TERM.../NOW THROUGH MONDAY NIGHT/...
FLOW FROM ABOUT 3000 FT ON UP IS FAIRLY RAPID AND SOUTHWESTERLY WITH
THE AIR DRYING ACROSS AMID MODERATE SUBSIDENCE INDICATED ON WATER
VAPOR IN THE LEFT ENTRANCE REGION OF A WEAK JET MAX. HOWEVER THE
LARGER SCALE FLOW IS DIVERGENT WITHIN A RIGHT ENTRANCE REGION OF THE
LARGER POLAR JET AND THIS IS INDUCING WEAK LOW PRESSURE/COASTAL
TROUGHING OVER THE WESTERN GULF OF MEXICO. A 17Z ASCAT PASS SHOWS
THIS TROUGH NICELY AND A LITTLE SWIRL IS EVIDENT ON VISIBLE
SATELLITE ABOUT 80 TO 100 MILES EAST SOUTHEAST OF BROWNSVILLE. THE
BOUNDARY LAYER IS DECOUPLED BY REMNANT FRONTAL INVERSION/COLD AIR
AND THE FLOW AT THE SURFACE CONTINUES TO BE LIGHT OUT OF THE NORTH
TO NORTHEAST. THE CLOUDS ARE BEING MAINTAINED BY WEAK LOW LEVEL
CURVATURE CONVERGENCE AND PERSISTENT OVERRUNNING AT 1000 TO 3000 FT.
TEMPERATURES ARE A LITTLE WARMER THAN 24 HOURS AGO.

TONIGHT...SURFACE LOW PRESSURE STRENGTHENS AND IT LOOKS AS IF THE
BROAD TROUGH IN THE WESTERN GULF WILL CONSOLIDATE MORE AROUND A
CENTRAL CYCLONE ABOUT 130 MILES EAST OF THE COAST. THIS SHIFTS WINDS
TO THE NORTHEAST AND CONTINUES OVERRUNNING SOUTHWESTERLY WINDS...LOW
LEVEL CONVERGENCE...AND BRINGS A LITTLE MORE MOIST LOW LEVEL AIR
INTO THE REGION OFF THE GULF. EXPECTING TO KEEP THE LOW CLOUD LAYER
AND A FEW OVERNIGHT AREAS OF RAIN AND SHOWERS COUPLED WITH DRIZZLE.
TEMPERATURES WILL PROBABLY ONLY FALL A FEW DEGREES TONIGHT.

MONDAY...MORE OF THE SAME EXPECTED FOR MONDAY WITH LOW LEVEL CLOUD
COVER PERSISTING...ESPECIALLY EAST OF 281 AS LOW PRESSURE HANGS OFF
THE COAST. INTERMITTENT SHOWERS/RAIN WILL BE POSSIBLE WITH THE
OVERRUNNING CONTINUING. DRY AIR WILL NOT BE FAR OFF THE DECK...SO A
FEW BREAKS IN THE CLOUDS ARE POSSIBLE...BUT FOR THE MOST PART
EXPECTING TO BE SOCKED IN. WITH THE LACK OF COLD ADVECTION AND
SLIGHTLY THINNER CLOUD COVER WILL BE ABLE TO GET MAX TEMPS UP
ANOTHER FEW DEGREES.

MONDAY NIGHT...AS HIGH PRESSURE INTENSIFIES OVER THE PLAINS IT
NUDGES THE COASTAL TROUGHING SOUTH AND EAST. AT THE SAME TIME WINDS
INCREASE FROM THE NORTH...INTERACTING WITH THE TROUGHING...AND WE
WILL SEE ANOTHER DROP IN OVERNIGHT DEWPOINTS. CLOUD COVER SHOULD
CONTINUE MOST OF THE NIGHT WITH THE LAYER OF HIGH RH INCREASING
BEHIND THE FRONT. A FEW SPRINKLES OR SHOWERS AMID MODERATE
NORTHEASTERLY WINDS THAT WILL ALSO AID IN KEEPING OVERNIGHT LOWS UP.

LONG TERM.../TUESDAY THROUGH SUNDAY NIGHT/...
UPPER LEVEL TROUGH OVER THE SOUTHWESTERN PORTION OF THE CONUS WILL
MOVE ACROSS THE CENTRAL PLAINS LATE MONDAY INTO TUESDAY PUSHING A
COLD FRONT INTO SOUTH TEXAS EARLY TUESDAY. THIS WILL ENHANCE CHANCE
OF SHOWERS ACROSS THE CWA WITH THE FRONTAL PASSAGE AND CHANGING TO
LIGHT RAIN BEHIND FROPA TUESDAY AFTERNOON INTO WEDNESDAY. DAYTIME HIGH
WILL REMAIN IN THE MID TO UPPER 40S OVER THE NORTHERN RANCHLAND AND
LOW TO MID 50S ALONG THE RIO GRANDE. MOISTURE CONTENT WILL BE VERY
LIMITED KEEPING LOW RAINFALL ACCUMULATION ACROSS THE AREA. A SERIES
OF SHORTWAVES WILL MOVE EAST WITHIN THE FLOW BUT WILL REMAIN NORTH
OF THE CWA. SURFACE LOW PRESSURE OVER THE GULF WATERS WILL ALSO
ENHANCE LIGHT RAIN AND DRIZZLE ALONG THE COASTAL COUNTIES OF THE CWA
WITH OVERCAST SKIES PREVAILING THROUGH THE WEEK. EXPECT TEMPERATURES
TO RETURN TO THE MID 50S AND 60S BY THE END OF THE WEEK WITH MORE
NORTHEAST TO EAST FLOW AS WARMER AIR MOVES INTO THE AREA.

A CLOSED LOW OVER BAJA CA WILL BEGIN TO MOVE EASTWARD INTO AZ FRIDAY
INTO SATURDAY WHILE SURFACE HIGH PRESSURE OVER THE SOUTHEAST PORTION
OF THE CONUS SHIFTS EASTWARD VEERING WINDS MORE E/SE OVER THE GULF.
THIS WILL INCREASE THE MOISTURE CONTENT ACROSS THE AREA SATURDAY AND
SUNDAY. AS THE CLOSE LOW MOVES ACROSS THE CENTRAL PLAINS...COASTAL
TROUGH DEVELOPS OVER THE GULF WATERS INCREASING THE CHANCE OF
SHOWERS OVER THE COASTAL AREA THROUGH THE WEEKEND. THE FAVORABLE
UPPER LEVEL ENERGY AND MOISTURE CONTENT WILL REMAIN TO THE NORTHEAST
PORTION OF THE STATE BUT A CHANCE OF SHOWERS CAN NOT BE RULED OUT FOR
OUR AREA MAINLY FAVORING THE COASTAL COUNTIES. THIS LOWS WILL PUSH
ANOTHER COLD FRONT ACROSS SOUTH TEXAS SUNDAY. TEMPERATURES WILL COOL
DOWN TO THE UPPER 60S ACROSS THE CWA.

MARINE...NOW THROUGH MONDAY NIGHT...PATCHY FOG WILL BE POSSIBLE
THROUGH OVERNIGHT TONIGHT WITH LOW PRESSURE CENTERED ABOUT 80
MILES EAST OF SOUTH PADRE ISLAND. WINDS AND SEAS WILL REMAIN
MOSTLY MODERATE THROUGH TONIGHT AND EARLY MONDAY BUT BEGIN TO
INCREASE FROM THE NORTH AND NORTHEAST THROUGH THE LATE AFTERNOON
AND MONDAY NIGHT. SEAS WILL INCREASE IN CONCERT WITH THE STRONG
WINDS. SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED MONDAY NIGHT.

TUESDAY THROUGH SUNDAY NIGHT...COLD FRONT WILL MOVE ACROSS
THE AREA EARLY TUESDAY ENHANCING SHOWER ACTIVITY ACROSS THE GULF WATERS
WITH POSSIBLE ISOLATED THUNDERSTORM DEVELOPING. SEAS WILL BUILD 6 TO
8 FEET WITH SCA CONDITIONS THROUGH TUESDAY NIGHT. A SMALL BREAK TO SCEC
CONDITIONS WEDNESDAY BUT QUICKLY RISE THURSDAY WITH NORTHEAST FLOW
BUILDING SEAS THROUGH FRIDAY NIGHT. NEXT WEEKEND...ANOTHER COLD
FRONT WILL MOVE ACROSS THE AREA INCREASING THE NORTHERLY WINDS
WITH POSSIBLE SCA AND SEAS RISING UP TO 8 FEET.
&&

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

$$

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