Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 291759
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1259 PM CDT FRI AUG 29 2014

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

&&

.AVIATION...CONVECTION ASSOCIATED WITH THE LOW PRESSURE HAS LOWER
OVER THE AREA WITH THE LATEST RADAR IMAGERY SHOWING A WEAK
CIRCULATION NE OF PORT MANSFIELD OVER THE LOWER TEXAS GULF WATERS.
AT THIS TIME...THERE ARE A FEW ISOLATED SHOWERS IN THE VICINITY OF
HARLINGEN AND BROWNSVILLE BUT MOST OF THE ACTIVITY IS NOT SHOWING
HIGHER REFLECTIVITY AND NO LIGHTNING ACTIVITY. WITH THE LACK OF
DAYTIME HEATING AND EARLIER RAINFALL AS THE ATMS STABILIZE ENOUGH
...EXPECT ACTIVITY CONTINUING TO REDUCE ANY ADDITIONAL DEVELOPMENT
AT THIS TIME. ANOTHER CHANCE OF SHOWERS RETURNS TONIGHT ACROSS THE
TERMINALS AS THE LOW RESTRENGTHENS THROUGH EARLY SATURDAY MORNING.

&&

.PREV DISCUSSION... /ISSUED 821 AM CDT FRI AUG 29 2014/

DISCUSSION...DUE TO LOW SWELLS AT THE BUOY WITH LIGHT TO MODERATE
WINDS CONTINUING...DECIDED TO CANCELLED THE HIGH RISK OF RIP
CURRENT AT THE BEACHES THIS MORNING. CONDITIONS WILL STILL BE
FAVORABLE FOR MODERATE RISK FOR TODAY.

PREV DISCUSSION... /ISSUED 722 AM CDT FRI AUG 29 2014/

DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

AVIATION...THE AVIATION OUTLOOK FOR TODAY WILL BE PRETTY
PROBLEMATIC DUE TO THE PRESENCE OF THE WEAK SURFACE LOW IN PLACE
OVER THE REGION. THE CURRENT CONV HAS BEEN HUGGING THE COASTLINE
THROUGHOUT THE OVERNIGHT HOURS AND HAS NOT MADE MUCH PROGRESS
SPREADING INTO THE LOWER RGV. THE PWAT VALUES OVER THE RGV REMAIN
VERY ELEVATED WITH A 00Z VALUE >2 INCHES WITH A PRETTY ELEVATED
CAPE FROM LAST NIGHT. WILL START OFF WITH VFR CONDITIONS INITIALLY
IN THE 12Z TAF SET WITH MENTIONS OF VCSH/TS. WILL MENTION SOME
TEMPO GROUPS LATER TODAY REDUCING CEILINGS AND VSBYS DOWN TO MVFR
LEVELS BY THE AFTERNOON HOURS. WILL THEN TRANSITION THE CONV MORE
TOWARDS SHRA LEVELS LATER THIS EVENING AS THE ATMS STABILIZES
SOMEWHAT.

PREV DISCUSSION... /ISSUED 358 AM CDT FRI AUG 29 2014/

SHORT TERM /NOW THROUGH SATURDAY/...CURRENTLY KBRO RADAR SHOWS AN
AREA OF CONV FIRING OVER KENEDY COUNTY AND EXTENDING DOWN SOUTHEAST
OVER THE LOWER TX COASTLINE INTO THE OFFSHORE GULF WATERS. THE
CELLULAR MOVEMENT WITHIN THIS AREA IS GENERALLY TO THE N-NW WITH THE
AREAL COVERAGE GRADUALLY EXPANDING OVER THE LAST SEVERAL HOURS. THE
00Z BRO SOUNDING SHOWED A VERY HEALTHY PWAT OF NEARLY 2.3 INCHES
WITH GOOD CAPE VALUES AROUND 3650 J/KG. SURFACE OBS INDICATE THAT
THE WEAK SURFACE LOW THAT WAS OFFSHORE MAY HAVE PUSHED INLAND AND
COULD BE CENTERED OVER THE RGV EARLY THIS MORNING. THIS SURFACE LOW
WILL LIKELY STAY NEARLY STATIONARY OR WILL DRIFT SLOWLY WEST LATER
TODAY THROUGH TONIGHT AND SATURDAY. THIS WILL LIKELY KEEP THE
EASTERN HALF OF THE BRO CWA ON THE MORE FAVORABLE SIDE OF THE
SURFACE LOW/TROUGH WHICH WILL PROVIDE A BETTER ENVIRONMENT FOR SLOW
MOVING HEAVY RAIN PRODUCING CONV DUE TO BETTER SURFACE CONVERGENCE.
THE CONV POTENTIAL THROUGHOUT THE SHORT TERM WILL ALSO BE ASSISTED
BY BROAD WEAKNESS IN THE 500 MB RIDGE AXIS ALOFT WHICH IS EXPECTED
TO LINGER OVER THE TX COASTLINE INTO SATURDAY. ADDING TO THIS...BOTH
THE NAM AND GFS FORECAST SOUNDINGS SHOW PRETTY DEEP LAYER TROPICAL
MOISTURE VALUES PERSISTING OVER THE CENTRAL AND EASTERN HALF OF THE
BRO CWA WITH BOTH MODELS SHOWING PWAT VALUES REMAINING WELL ABOVE
THE 2 INCH MARK THROUGH SATURDAY.

SO CONSIDERING ALL OF THESE FACTORS...THE MAIN ISSUE BOILS DOWN TO
HOW HIGH OF POPS TO GO WITH THROUGHOUT THE SHORT TERM. THE MAV POPS
ARE A LITTLE LOWER IN COMPARISON TO THE WETTER MET AND ECMWF
NUMBERS. WILL LEAN CLOSER TO THE MET AND ECMWF POPS WHICH APPEAR TO
HAVE A LITTLE BETTER HANDLE ON THE TIMING AND STRENGTH OF THE CONV
THROUGH SAT.

MULLED OVER ISSUING AN FFA FOR THE EASTERN PORTIONS OF THE CWA FOR
TODAY BUT DECIDED AGAINST IT AS SOIL MOISTURE VALUES REMAIN PRETTY
LOW DUE TO RECENT HIGH TEMPS AND DRY CONDITIONS. HOWEVER WILL
CONTINUE TO MENTION LOCALLY HEAVY RAINFALL POSSIBLE THROUGHOUT
TODAY. AN FFA MAY NEED TO BE RECONSIDERED LATER TONIGHT OR SATURDAY
IF THE CONV REMAINS MORE WIDESPREAD AND STATIONARY.

TEMP TRENDS WILL HINGE GREATLY ON THE CONV COVERAGE THROUGH SAT.
CONSIDERING THE HIGHER CONV CHCS AND CLD COVER WILL GO TOWARDS A
SLIGHTLY COOLER MODEL CONSENSUS FOR BOTH MAXES AND MINS.

LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
LITTLE CHANGE TO INHERITED FORECAST...BAY OF CAMPECHE SYSTEM NEXT
WEEK DETERMINES MUCH OF OUR WEATHER.

MODEST SOUTHEASTERLY LOW LEVEL FLOW WILL CONTINUE ON SUNDAY WHICH
SHOULD HELP LIMIT PRECIP POTENTIAL IN THE AFTERNOON DESPITE ABUNDANT
LOW LEVEL MOISTURE. CONTINUED A 20 PCT SLIGHT AFTERNOON CHANCE OVER
LAND WHICH CARRIED FORWARD INTO MONDAY AS MID LEVEL AND ULTIMATELY
SURFACE RIDGING BEGINS TO RECENTER MORE OVER FLORIDA AND GEORGIA
THAN OVER THE NORTH CENTRAL GULF OF MEXICO.

LATE MONDAY INTO TUESDAY A TROPICAL WAVE ENTERS THE BAY OF CAMPECHE
AND THE BEST OVERALL MOISTURE VALUES BEGIN TO MOVE INTO THE AREA AS
LOW LEVEL FLOW OVER THE GULF OF MEXICO BECOMES MORE EASTERLY. THAT
TROUGHING/LOW PRESSURE AREA DEPENDS ON WEDNESDAY AND OUR EASTERLY
FLOW BECOMES STRONGER. CONTINUED A 30 PCT POP BASICALLY FROM TUESDAY
AFTERNOON INTO WEDNESDAY AFTERNOON WITH ALL OF THE AVAILABLE
MOISTURE. GFS REMAINS MORE AGGRESSIVE WITH THE DEPTH OF THE
TROUGHING OVER THE BAY OF CAMPECHE AND USES THE LOW PRESSURE AND THE
INTERACTION WITH RIDGING OVER FLORIDA TO CREATE A LONG STRONG
EASTERLY FETCH OVER THE GULF. DISCOUNTED THESE WIND SPEEDS A BIT
CONSIDERING THE POSSIBILITY OF TROPICAL CYCLOGENESIS IN THIS AREA
WHICH WOULD CREATE A MUCH TIGHTER WINDFIELD THAN THE BROAD LUMBERING
LOW THE GFS IS SUGGESTING. PREFER THE ECMWF SOLUTION FOR NOW WHICH
HAS A MODEST TROPICAL WAVE MOVING SLOWLY OVER THE BAY BEFORE MOVING
INLAND ON THURSDAY WITH THE PEAK OF 500MB VORTICITY SOUTH OF HERE.

NHC CONTINUES TO HIGHLIGHT THIS REGION IN ITS TROPICAL WEATHER
OUTLOOK PRODUCT AS A LOW PROBABILITY AREA AND THAT APPEARS JUSTIFIED
GIVEN THE LOW SHEAR/WARM SST/OHC ENVIRONMENT THE WAVE/DISTURBANCE
WILL BE ENTERING. ITS NOT SCIENTIFICALLY POSSIBLE TO PROVIDE MUCH
MORE AT THIS TIME THAN ASK EVERYONE TO REMAIN AWARE OF FORECASTS
OVER THE NEXT FEW DAYS...PARTICULARLY LATE THIS WEEKEND INTO EARLY
NEXT WEEK BECAUSE CYCLONE OR NO CYCLONE COULD HAVE IMPLICATION ON OUR
FORECAST EVEN IF WE ARE NOT DIRECTLY IMPACTED.

THURSDAY INTO FRIDAY MID LEVEL RIDGING SHIFTS BACK WESTWARD AND THE
HOT AND DRY SOUTHEASTERLY REGIME RETURNS AND PRECIP CHANCES STEADILY
BEGIN TO DROP AS HIGH TEMPERATURES RISE. /68-JGG/

MARINE...
NOW THROUGH SATURDAY...CURRENTLY SURFACE OBS AND BUOY DATA
SHOWS A LIGHT TO MODERATE S-SE SURFACE FLOW CONTINUING OVER THE BAY
AND GULF WATERS EARLY THIS MORNING WITH OFFSHORE SEAS HOLDING AROUND
4 FEET. THIS LIGHT TO MODERATE SOUTH TO SOUTHEAST SURFACE FLOW WILL
LIKELY PERSIST INTO SATURDAY AS THE PGF REMAINS FAIRLY WEAK. THIS
SHOULD KEEP THE BAY AND GULF CONDITIONS WELL BELOW SCA CRITERIA
THROUGHOUT THE SHORT TERM.

SATURDAY NIGHT THROUGH WEDNESDAY...
MODERATE SOUTHEAST WINDS ARE FORECAST MONDAY AND TUESDAY TO BECOME
STRONGER AND MORE EASTERLY AS LOW PRESSURE FORMS IN THE SOUTHERN
GULF OF MEXICO/BAY OF CAMPECHE. SMALL CRAFT ADVISORY LEVEL WINDS
WILL BECOME POSSIBLE BY TUESDAY WITH SEAS BECOMING ROUGHER DUE TO A LONG
EASTERLY FETCH OVER THE GULF OF MEXICO. THERE IS A SMALL POSSIBILITY
OF TROPICAL CYCLONE FORMATION IN THE BAY OF CAMPECHE NEXT WEEK
AND MARINERS ARE ASKED TO REMAIN ALERT TO THE LATEST FORECASTS
REGARDING THIS SYSTEM.

&&

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

$$

THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
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