Area Forecast Discussion
Issued by NWS Brownsville, TX

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS64 KBRO 011937
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
237 PM CDT MON SEP 1 2014

.SHORT TERM /NOW THROUGH TUESDAY NIGHT/...NEXT 36 HOURS BEGINS
TRANSITION FROM INVERTED TROUGH FROM THE PREVIOUS WEEK OVER TO THE
TROPICAL WAVE LURKING IN THE SE BAY OF CAMPECHE. PW VALUES THIS
MORNING WERE ABOVE 2 INCHES...AND MODELS KEEP DEEP MOISTURE IN THE
VICINITY AND SLOWLY BUILD IT AS THE GULF FEATURE DRIFTS WNW.

OVERNIGHT TONIGHT...VIS SATELLITE IMAGERY SHOWS A CONTINUAL FEED OF
STREAMER SHOWERS UPSTREAM FRO THE VALLEY...WHICH WILL CONTINUE TO
STREAM INTO THE REGION OVERNIGHT. OVERALL COVERAGE WILL BE LOW...BUT
HI PW SIGNAL WILL MEAN ANY SHOWER WILL PROVIDE AMPLE RAINFALL IN A
SMALL AREA. SHOWERS WILL BE LIMITED TO THE IMMEDIATE COASTAL AREAS
THROUGH SUNRISE. TOMORROW THE DISTURBANCE IS IN THE OPEN WATERS OF
THE BAY OF CAMPECHE...WELL TO THE SOUTH OF THE REGION. WITH THE H5
RIDGE BUILDING IN BEHIND THE DEPARTING TROUGH...THE GULF FEATURE
WILL LIKELY DEFLECT WWD TOWARD THE CENTRAL MEXICO COAST. INSTABILITY
AROUND THE OUTER EDGE OF THIS FEATURE AND INCREASED MOISTURE IN THE
ENTIRE PARCEL WILL INCREASE RAIN CHANCES...ESPECIALLY DURING DAYTIME
HEATING. MINOR FLOODING OF URBAN AREAS AND LOW LYING REGIONS WILL
BECOME A CONCERN TUESDAY AFTERNOON. HIGH TEMPERATURES WILL BE HELD
BACK BY INCREASED CLOUD COVER...KEEPING HIGHS ONLY IN THE LOW TO MID
90S.

PW CONTINUES TO INCREASE TUESDAY NIGHT...BUT HEATING INSTABILITY
WILL BE LOST. SHOWER AND THUNDERSTORM ACTIVITY WILL STILL BE
SCATTERED...ESPECIALLY NEAR THE COAST. WILL NEED TO WATCH FOR MORE
ORGANIZED CONVECTION MOVING IN FRO THE SOUTHWEST TUESDAY NIGHT
BRINGING HEAVIER RAINFALL.

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...THE MAIN FOCUS OF THE EARLY
PART OF THE LONG TERM PERIOD WILL BE THE TROPICAL SYSTEM IN THE BAY
OF CAMPECHE. CONDITIONS TO THE SOUTH FAVOR DEVELOPMENT BUT LONGEVITY
WILL BE AN ISSUE...WITH THE MODELS MOVING WHATEVER DEVELOPS ON THE
BAY OF CAMPECHE INTO THE EASTERN MEXICAN COAST TUESDAY NIGHT INTO
WEDNESDAY. WX RAMIFICATIONS FOR THE CWA WILL DEPEND ON THE MOISTURE
THAT FEEDS NORTH ON THE LARGER SCALE SOUTHEAST FLOW DOMINATING THE
GULF.

NONETHELESS...UNSETTLED WEATHER WILL RETURN TO THE CWA IN THE EARLY
LONG TERM AS DEEP TROPICAL MOISTURE INCREASES. PRECIPITABLE WATER
VALUES WILL CLIMB ABOVE TWO INCHES BY LATE TUESDAY...WHICH WILL
SUPPORT A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS TUESDAY THROUGH
LATE WEEK. THE GFS AND ECMWF WERE BALANCED WITH PERSISTENCE TO YIELD
BETTER THAN EVEN ODDS...OR 50 PERCENT...RAIN CHANCES FOR THE AREA.
SLIGHTLY HIGHER AMOUNTS WERE NOTED OVER THE MARINE AREAS. IN ANY
CASE...A FEW DAYS OF UNSETTLED WEATHER WILL BE IN STORE...WITH AREAL
AMOUNTS OF RAINFALL LIKELY TO VARY FROM A FEW TENTHS OF AN INCH TO A
FEW INCHES DEPENDING ON WHETHER ANY PARTICULAR SPOT ENDS UP UNDER A
HEAVILY LOADED TROPICAL TOWER.

THE ECMWF AND GFS POPS ARE FAIRLY SIMILAR WITH POPS WED THROUGH
THURS AS THE TROPICAL MOISTURE ASSOCIATED WITH THE BROAD SURFACE LOW
SURGES WEST AND NORTHWEST OVER THE REGION. DEEPER MOISTURE WILL
GRADUALLY DIMINISH AS THE WEEKEND APPROACHES...AND WILL THUS TREND
DOWN CONV CHCS INTO SATURDAY AND SUNDAY AS THE TROPICAL FEED SHIFTS
WEST AND NORTH AROUND THE WEST SIDE OF THE SOUTHERN U.S. 500 MB
RIDGE AXIS.

SINCE THE LONGER RANGE MODEL GUIDANCE IS IN PRETTY GOOD AGREEMENT IN
THE HANDLING OF THIS TROPICAL SYSTEM...OPTED TO GO WITH A GENERAL
MODEL BLEND OF THE ECMWF AND THE GFS FOR BOTH POPS AND TEMPS THROUGH
DAY 7. MAX TEMPS WILL LIKELY BE SUPPRESSED A BIT WED AND THURS AS
CONV CHCS MAX OUT OVER THE AREA. WILL THEN TREND THE TEMPS UP A BIT
LATER AS CONV CHCS FADE A BIT AND A LITTLE MORE DIURNAL HEATING IS
EXPECTED IN THE AFTERNOON.

OVERALL CONFIDENCE IN THE LONGER RANGE FORECAST WORDING IS ON THE
INCREASE AS THE MODEL GUIDANCE STARTS TO GEL TOWARDS A SIMILAR
SOLUTION. RUN TO RUN CONSISTENCY WITH THE GFS MEX MOS HAS ALSO
BEEN PRETTY STABLE OVER THE LAST SEVERAL RUNS KEEPING THE HIGHEST
POPS FOR WED AND THURS.

RAIN CHANCES WILL DECREASE TOWARD NEXT WEEKEND AS THE SYSTEM MOVES
INLAND...AND CONDITIONS WILL RECOVER WITH LOWER...MORE TYPICAL
MOISTURE. THERE WILL BE A GOOD MIX OF CLOUDS AND SUN...BUT LIKELY A
BIT MORE CLOUDS...AND HIGH TEMPS WILL BE HELD DOWN BELOW NORMAL. DEW
POINTS WILL REMAIN IN THE 70S HOWEVER...AND HEAT INDEX VALUES WILL
REMAIN WELL INTO THE 90S OR EVEN NEAR THE CENTURY MARK...INCLUDING
EASTERN SECTIONS.

&&

.MARINE...
NOW THROUGH TUESDAY NIGHT...INCREASING AGITATION FORECAST FOR THE
MARINE AREAS DURING THE NEXT 36 HOURS AS A TROPICAL SYSTEM
DEVELOPS IN THE BAY OF CAMPECHE. WINDS WILL INCREASE TO AROUND 15
KNOTS TOMORROW AS THE LOW MOVES ACROSS THE SOUTHERN GULF...WITH
SOME WINDS NEARING 20 KNOTS TUESDAY NIGHT. LONG PERIOD SWELLS WILL
START TO INCREASE LATER TOMORROW...WITH SEAS REACHING 6 TO 7 FEET
FOR THE GULF WATERS BY TUESDAY EVENING. SMALL CRAFT ADVISORIES MAY
BE NEEDED FOR THE WATERS BEYOND 20NM TUESDAY NIGHT UNTIL THE
TROPICAL FEATURE MOVES INLAND.

WEDNESDAY THROUGH FRIDAY...SMALL CRAFT ADVISORY CONDITIONS WILL
LIKELY BE IN EFFECT WEDNESDAY DUE TO SWELL FROM A TROPICAL SYSTEM
MOVING ACROSS THE BAY OF CAMPECHE TOWARD THE MEXICAN COAST. SOUTH
EAST WINDS WILL BE IN THE 15 TO 20 KNOT RANGE. THE ADVERSE MARINE
CONDITIONS WILL IMPROVE WEDNESDAY NIGHT HOWEVER...AS THE TROPICAL
SYSTEM MOVES INLAND AND THE ASSOC SWELL GENERATING WINDS DECREASE.
THURSDAY WILL THEREFORE BE MORE OF A SMALL CRAFT EXERCISE CAUTION
DAY. FRIDAY WILL RESULT IN FURTHER IMPROVEMENT IN MARINE WINDS AND
WAVES...WITH LOW TO MODERATE SOUTHEAST WINDS AND LOW SEAS. UNSETTLED
WEATHER WITH ONGOING SHOWERS AND A FEW THUNDERSTORMS WILL BE PART
AND PARCEL OF THE FORECAST.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  81  91  79  88 /  20  50  40  70
BROWNSVILLE          79  93  78  88 /  20  50  50  60
HARLINGEN            78  94  77  89 /  20  50  40  60
MCALLEN              79  96  78  90 /  10  50  30  60
RIO GRANDE CITY      80  98  78  90 /  10  40  30  60
SOUTH PADRE ISLAND   81  88  80  87 /  20  50  40  70

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...HIGH RIP CURRENT RISK UNTIL 7 PM CDT THIS EVENING FOR TXZ251-256-
     257.

GM...NONE.
&&

$$

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

64/54/MARTINEZ





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.