Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 272337
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
637 PM CDT SAT SEP 27 2014

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

&&

.AVIATION...RELATIVELY HEAVY SHOWERS ARE EXPECTED TO CONTINUE IN
CAMERON AND WILLACY COUNTIES FOR ANOTHER COUPLE OF HOURS ROTATING
AROUND A WEAK LOW PRESSURE AREA. WEST OF THERE RAINFALL SHOULD
PRETTY MUCH HAVE ENDED FOR THE NIGHT. COASTAL TROUGHING SHOULD
WEAKEN AS UPPER LEVEL LOW PRESSURE MOVES NORTHEAST OUT OF THE AREA
AND EXPECT A TRANSITION TOWARDS CLEARER WEATHER AND VFR CIG/VISBY
OVERNIGHT TONIGHT. WILL BE MONITORING FOR GROUND FOG IN THE EARLY
MORNING HOURS BUT PROBABILITY TOO LOW FOR TAF MENTION. BETTER
WEATHER AND VFR/CIG VISBY FORECAST ACROSS THE AREA SUNDAY WITH
VERY LOW RAIN CHANCES. /68-JGG/

&&

.PREV DISCUSSION... /ISSUED 603 PM CDT SAT SEP 27 2014/

DISCUSSION...LARGE UPPER LEVEL SHORTWAVE TROUGH THAT SHOULD MARK
A CHANGE TO STRONG SUBSIDENCE AND MID LEVEL DRYING IS MOVING INTO
THE CWA. THIS TROUGH IS ALSO HELPING CONTINUE COASTAL TROUGHING
THAT IS RESULTING IN ROUGH EASTERLY SWELL AND COASTAL FLOODING.

THE AREAS WHERE PRECIP HAS ALREADY ENDED APPEAR TO BE DONE FOR THE
NIGHT...BUT WILL BE MONITORING CAMERON/WILLACY/KENEDY WITH AMPLE
MOISTURE AND RESIDUAL LIFT. WATER VAPOR TRENDS SEEM TO SHOW THE
WAVE HAS STOPPED DIGGING AS VIGOROUSLY AND IT MAY TAKE ANOTHER
COUPLE OF HOURS TO SEE THE SPIGOT CUT OFF IN THE EAST...WHERE
2.1/2.2 PWATS AND ONGOING CONVECTION WILL STILL POSE A FLOOD CONCERN.

TIDAL GAUGES ARE A LITTLE HIGHER THAN ANTICIPATED AND WEBCAMS FROM
SOUTH PADRE ISLAND SHOW THE WATER LEVELS UP TO THE DUNE LINE. HIGH
TIDE IS STILL ABOUT 90 MINUTES AWAY WITH EASTERLY SWELL CONTINUING
SO REPLACED THE COASTAL FLOOD STATEMENT WITH A COASTAL FLOOD
ADVISORY FOR WATER INTO THE DUNE LINES THROUGH THIS HIGH TIDE
CYCLE. /68-JGG/

PREV DISCUSSION... /ISSUED 405 PM CDT SAT SEP 27 2014/

SHORT TERM /NOW THROUGH SUNDAY NIGHT/...WIDESPREAD RAIN EVENT FRO
THE PAST FEW DAYS WILL BEGIN TO WIND DOWN DURING THE NEXT 36 HOURS
AS DRY AIR CAPS OFF THE ATMOSPHERE. UNTIL THEN...SHOWERS AND A FEW
THUNDERSTORMS WILL CONTINUE TO PRODUCE VERY HEAVY RAINFALL IN PLACES
INTO TOMORROW MORNING.

TONIGHT...THE H5 LOW CURRENTLY CENTERED JUST NORTH OF DRT IS MOVING
NE...BEING DRAWN NORTHWARD BY THE RETREATING TROUGH AND PUSHED OUT
BY LARGER TROUGH ACROSS THE WEST COAST. SIGNIFICANTLY DRIER AIR IS
NOTED TO THE NW APPROACHING THE REGION. UNTIL WINDS ALOFT TURN FROM
THE SW TO THE NW...RAIN WILL CONTINUE TO AFFECT THE REGION AS MOIST
SW FLOW INTERACTS WITH WEAK COASTAL TROUGH.

SUNDAY...WITH THE H5 LOW AXIS TO THE EAST...NW WINDS WILL QUICKLY
INTRODUCE DRIER AIR AT MIDLEVELS. THIS WILL SLOWLY BRING TO AN END
THE SHOWER ACTIVITY AREAWIDE...WITH WESTERN AREA DURING THE EARLY
AFTERNOON AND COASTAL COUNTIES LATE IN THE AFTERNOON. SHOWERS WILL
BE MUCH MORE ISOLATED...AND WITH DRIER AIR INGESTING INTO THE
MIDLEVELS OF ANY SHOWERS...SHOWERS WILL HAVE A HARDER TIME PRODUCING
HEAVY RAINFALL. HIGH TEMPERATURES WILL CLIMB A FEW MORE DEGREES THAN
THE PAST SEVERAL DAYS...BUT WILL STILL REMAIN BELOW 90 DEGREES.

SUNDAY NIGHT...WITH THE LOSS OF DAYTIME HEATING AND FULLER
INTRODUCTION OF DRY AIR...WILL BE VERY TOUGH TO HAVE ANY SHOWERS
OVERNIGHT. THE BEST CHANCES WOULD BE ALONG THE IMMEDIATE COAST WITH
STREAMER SHOWERS MOVING ASHORE LATE.

LONG TERM /MONDAY THROUGH SATURDAY/...A SERIES OF 500 MB TROUGHS
WILL SWING ACROSS THE WESTERN AND CENTRAL PORTIONS OF THE LOWER
48 STATES OVER NEXT WEEK. THIS APPROACH AND PASSAGE OF THESE
FEATURES WILL ALLOW FOR DRIER AIR TO FILTER INTO THE REGION IN THE
MIDDLE AND UPPER PORTIONS OF THE ATMS. THIS WILL HOLD DOWN THE
PCPN CHCS EARLY NEXT WEEK. HOWEVER SOME DEEPER LAYER TROPICAL
MOISTURE WILL START TO ADVECT BACK UP TO THE NORTH FROM CENTRAL
MEXICO AND THE SOUTHWESTERN GULF OF MEXICO FRIDAY AND SATURDAY.
ALSO A COLD FRONT MOVING SOUTH OUT OF CENTRAL TX WILL START TO
PUSH INTO DEEP SOUTH TX FRIDAY NIGHT INTO SATURDAY WHICH WILL
LIKELY INCREASE THE SURFACE CONVERGENCE ALLOWING FOR SOME BETTER
CONV POTENTIAL.

THE LONGER RANGE MODELS ARE IN PRETTY GOOD AGREEMENT IN THE
OVERALL SYNOPTIC PATTERN ON THROUGH DAY 7. THE BIGGEST DIFFERENCE
IS THAT THE ECMWF MAINTAINS A LITTLE WETTER PATTERN THROUGH NEXT
SATURDAY VERSUS THE GFS. FOR OVERALL TEMP TRENDS BOTH THE MODELS
ARE IN GENERALLY GOOD AGREEMENT DURING THE OUTLOOK PERIOD. SO WILL
GO WITH A ROUGH 50/50 MODEL BLEND OF THE GFS AND ECMWF FOR BOTH
TEMPS AND POPS.

OVERALL CONFIDENCE IN THE LONGER RANGE FORECAST WORDING IS PRETTY
GOOD DUE TO GOOD AGREEMENT BETWEEN THE GFS AND THE ECMWF. ALSO RUN
TO RUN CONSISTENCY WITH THE GFS MEX MOS TEMPS AND POPS IS PRETTY
STABLE.

MARINE...NOW THROUGH SUNDAY NIGHT...AGITATED CONDITIONS WILL RELAX
AS THE COASTAL TROUGH COLLAPSES DURING THE DAY SUNDAY. SEAS WILL
BEGIN AROUND 6 FEET...BEING CHURNED BY LOCAL THUNDERSTORM
ACTIVITY...BEFORE RELAXING TO 2 TO 3 FEET BY SUNDAY EVENING. WINDS
OF 15 TO 20 KNOTS TONIGHT WILL RELAX TO AROUND 10 KNOTS BY SUNDAY
AFTERNOON...WITH IMPROVED MARINE ACTIVITY CONDITIONS.

MONDAY THROUGH THURSDAY...A FAIRLY WEAK PGF WILL PREVAIL ACROSS
THE LOWER TX BAY AND GULF WATERS ON MON AND TUES WHICH WILL
MAINTAIN FAIRLY LOW WINDS AND SEAS. HOWEVER A SURFACE LOW
DEVELOPING OVER THE TX/OK PANHANDLE REGION WILL INCREASE THE
SURFACE WINDS FROM THE S-SE FOR WED AND THURS. THIS WILL BUILD UP
THE WINDS AND SEAS A BIT MORE TOWARDS THE END OF NEXT WEEK. BUT
NOT SCA CONDITIONS EXPECTED AT THIS TIME.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...COASTAL FLOOD ADVISORY UNTIL 3 AM CDT SUNDAY FOR TXZ251-256-257.

GM...NONE.
&&

$$

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

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