Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 280726
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
226 AM CDT THU APR 28 2016

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

&&

.AVIATION...IR SATL IMAGERY AND SURFACE OBS FROM AROUND THE RGV
INDICATE THAT A LOW STRATUS DECK IS SPREADING STEADILY OVER THE
REGION REDUCING CEILINGS DOWN TO IFR LEVELS. IN ADDITION AREAS OF
FOG AND HAZE CONTINUE TO REDUCE THE VSBYS DOWN TO THE 2 TO 5 NM
RANGE. THE LOW CLDS AND FOG/HAZE WILL PERSIST ON THROUGH THE EARLY
TO MID MORNING HOURS. AFTER SUNRISE AND THE INCREASE IN THE LOW
LEVEL MIXING EXPECT CONDITIONS TO TREND CLOSER TO MVFR/VFR LEVELS
THROUGH THE AFTERNOON AND EARLY EVENING HOURS. BOTH THE NAM AND
GFS GUIDANCE THROUGH THE NEXT 24 HOURS SHOW THE LOWER CEILINGS
RETURNING LATE IN THE CURRENT TAF PERIOD RESULTING IN A RETURN OF
NEAR IFR LEVELS.

&&

.PREV DISCUSSION... /ISSUED 700 PM CDT WED APR 27 2016/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...HAZY CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD
WITH MOSTLY MVFR VSBYS. LOW CLOUDS RETURN THIS EVENING WITH
POSSIBLE IFR CIGS AROUND DAWN LASTING THROUGH MID MORNING. WINDS
PICK BACK UP AS A WARM FRONT MOVES NORTH OF THE AREA AND LOW
PRESSURE STRENGTHENS ACROSS THE PLAINS. GUSTS UP TO 25 KNOTS FROM
THE SOUTHEAST ARE POSSIBLE.

PREV DISCUSSION... /ISSUED 244 PM CDT WED APR 27 2016/

SHORT TERM /NOW THROUGH THURSDAY NIGHT/...THE WEAK FRONT THAT
HAS BEEN MENTIONED IN PREVIOUS DISCUSSION HAD ENOUGH MOMENTUM TO
CLEAR THE COAST THIS MORNING. DRIER AIR IS SPREADING SLOWLY
EASTWARD AND MAY MAKE IT TO THE COAST BY SUNSET WITH DEW POINTS
FALLING INTO THE MID TO UPPER 60S WITH 30S...40S AND 50S OUT WEST.
THE NORTHWEST TO NORTHEAST WINDS HAVE ALSO PUSHED BACK THE HAZE
FROM THE AGRICULTURAL BURNS OVER THE SOUTHERN MEXICO WITH MOST
AREAS SEEING SOME IMPROVEMENT.

FAIR CONDITIONS TO PERSIST INTO THE EVENING HOWEVER THE 12Z MODEL
SUITE SUGGEST THE FRONT PULLS UP STATIONARY THIS EVENING AND BEGINS
TO RETURN AS WARM FRONT LATER TONIGHT.  THIS WILL ALLOW FOR A LOW
STRATUS LAYER AND A MIX OF FOG AND HAZE TO RETURN OVERNIGHT INTO
THURSDAY MORNING. NAM, GFS AND ECMWF ALL SHOW SOME TRIVIAL LOW QPF
ALONG THE WARM FRONT BUT THIS SHOULD ONLY AMOUNT TO SOME DRIZZLE OR
A FEW SPRINKLES AND WILL ONLY MENTION 10 TO 14 PERCENT AT THIS TIME.
AS FOR TEMPERATURES LOWS ARE LIKELY TO OCCUR SHORTLY AFTER MIDNIGHT
OR JUST PRIOR TO THE WARM FRONT PASSAGE. LOWS MAY DIP INTO THE MID
60S ACROSS THE NORTH AND WEST AND MAYBE THE UPPER 60S IN THE RGV BUT
THEY HAVE A LONG WAY TO FALL WITH TEMPS TOPPING OUT IN THE 90S TO
NEAR 100 TODAY.

THURSDAY WILL START OFF CLOUDY BUT THE REGION SHOULD SEE SOME BREAKS
IN THE CLOUDS IN THE AFTERNOON AS THE WARM FRONT MOVES NORTH OF THE
CWA AND SOUTHEASTERLY WINDS INCREASE TO BREEZY LEVELS MIXING OUT
SOME OF THE LOW LEVEL MOISTURE. HIGHS TO RECOVER WELL INTO THE 90S
ABOUT THE SAME OR A DEGREE OR TWO LOWER THEN TODAY. EXPECTING THE
HAZE TO RETURN AS THE SOUTHEAST WINDS PICK UP WITH NO RELENT IN THE
AGRICULTURAL BURNING IN THE YUCATAN AND CENTRAL AMERICA.

THE LATEST AIR QUALITY FORECAST FROM TCEQ INDICATES THAT HAZE AND
SMOKE FROM AG BURNING ONGOING IN SOUTHERN MEXICO AND CENTRAL AMERICA
WILL CONTINUE IMPACT SOUTH TEXAS THURSDAY AND FRIDAY WITH LEVELS
ONCE AGAIN REACHING THE "UNHEALTHY FOR SENSITIVE GROUPS" CATEGORY.

LONG TERM /FRIDAY THROUGH WEDNESDAY/...A SERIES OF UPPER LEVEL
SYSTEMS WILL TRAVEL ACROSS THE WESTERN CONUS INTO THE CENTRAL
PLAINS DURING THE LONG TERM PERIOD. FIRST SYSTEM WILL EJECT
NORTHEAST INTO THE PLAINS FRIDAY WHILE THE SECOND SYSTEM DIGS INTO
THE FOUR CORNERS AND LIFTS NORTHEAST INTO THE NORTHERN ROCKIES BY
TUESDAY. THIS STRONG LOW PRESSURE WILL KEEP A SOUTHWESTERLY FLOW
ALOFT STRENGTHENING CAP ACROSS S TEXAS FRIDAY. NEAR THE SURFACE
THE GRADIENT WILL STRENGTHEN SE WINDS FRIDAY AFTERNOON WITH BREEZY
CONDITIONS BECOMING WINDY NEAR THE COASTAL COUNTIES. FRONTAL
BOUNDARY ASSOCIATED WITH THE LOW PRESSURE WILL MOVE ACROSS THE CWA
SATURDAY. 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. EXPECT DRY CONDITIONS FRIDAY
TRANSITIONING TO CHANCE OF SHOWERS AND THUNDERSTORMS SATURDAY WITH
THE PASSAGE OF THE BOUNDARY ACROSS THE AREA. 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 WINDS QUICKLY TURN BACK TO THE SOUTHEAST SUNDAY AND
DRY CONDITIONS RETURN.

SOUTHWESTERLY FLOW WILL DOMINATE THE WEATHER PATTERN FOR THE EARLY
PART OF THE WEEK AS ANOTHER LOW PRESSURE MAKES ITS WAY INTO THE
PACIFIC NORTHWEST AND INTO THE DESERT SW SUN INTO MON. MODELS
DIFFER INTO EARLY NEXT WEEK WITH THE PLACEMENT OF THE THIRD LOW.
ABUNDANT MOISTURE WILL BE AVAILABLE WITH SE FLOW CONTINUING ACROSS
THE REGION. THIS WILL ENHANCE CONVECTION MAINLY FAVOR S CENTRAL
TEXAS. THIS SYSTEM WILL BRING ANOTHER FRONT BUT THE TIMING STILL
DIFFERS WITH THE GFS A BIT FASTER AND STALLING OVER THE AREA WHILE
ECMWF SLOWS DOWN AND MOVES THROUGH THE CWA WITH A MORE N FLOW. THE
GFS ALSO IS A LITTLE DIFFERENT AND PLACES THE BETTER ATMOSPHERIC
CONDITIONS FURTHER NORTH AND A BULK OF THE PRECIPITATION THERE AS
WELL.

MARINE...NOW THROUGH THURSDAY NIGHT...WEAK FRONT HAS MOVED SE
OF THE COASTAL WATERS AND IS EXPECTED TO RETREAT NORTHWARD LATE
TONIGHT INTO THURSDAY MORNING. LIGHT NORTH TO EAST THE REST OF
THE DAY AND EARLY EVENING TO RETURN SOUTHEAST OVERNIGHT. STRONGER
WINDS DEVELOPING LATER THURSDAY AND THURSDAY NIGHT AS THE PRESSURE
GRADIENT STRENGTHENS IN RESPONSE TO ANOTHER MID LEVEL TROUGH
MOVING INTO THE DESERT SOUTHWEST. WINDS COULD APPROACH SMALL
CRAFT ADVISORY LEVELS OVER THE OUTER WATERS LATER THURSDAY NIGHT.

FRIDAY THROUGH WEDNESDAY...A SERIES OF LOW PRESSURE WILL TRAVEL
ACROSS THE DESERT SW INTO CENTRAL PLAINS THROUGH THE LONG TERM
STRENGTHENING THE PRESSURE GRADIENT ACROSS THE GULF OF MEXICO.
THIS WILL ALLOW FOR SE WINDS TO INCREASE TO WIND CONDITIONS.
EXPECT SCEC AND CLOSE TO SCA CONDITIONS BY FRIDAY AFTERNOON. THE
SEAS WILL BEGIN TO BUILD CLOSE TO 6 TO 8 FEET ACROSS THE GULF
WATERS. A FRONT WILL MOVE ACROSS THE GULF WATERS SATURDAY AND
ENHANCE A FEW SHOWERS AND THUNDERSTORMS IN THE AFTERNOON BUT WINDS
WILL RETURN QUICKLY TO THE E SUNDAY AND MONDAY. 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
SYSTEM WILL ENHANCE ANOTHER ROUND OF CONVECTION MONDAY THROUGH
WEDNESDAY BUT THERE ARE SOME DIFFERENCES IN THE MODEL GUIDANCE.

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

$$

THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WEATHER.GOV/RGV

SHORT TERM...60
LONG TERM...63



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