Area Forecast Discussion
Issued by NWS Brownsville, TX

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000
FXUS64 KBRO 301219 AAA
AFDBRO

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BROWNSVILLE TX
719 AM CDT SAT AUG 30 2014

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

&&

.AVIATION...THE 500 MB INVERTED TROUGH WILL DRIFT SLOWLY WEST
ACROSS DEEP SOUTH TEXAS TODAY WHICH WILL MAINTAIN THE CONV THREAT
ACROSS THE LOWER RGV THROUGHOUT THE MORNING AND AFTERNOON HOURS.
THE MORNING CONV AREAS CONTINUE MOVING GENERALLY NORTH MAINLY
ALONG AND EAST OF HIGHWAY 281. WILL GO WITH MAINLY VFR CONDITIONS
THROUGHOUT THE MORNING HOURS WITH THE MORNING CONV PERIODICALLY
REDUCING CEILINGS AND VSBYS DOWN TO MVFR LEVELS THROUGHOUT THE
FIRST HALF OF THE CURRENT TAF SET. THE ATMS SHOULD BECOME MORE
STABILIZED LATER TODAY AS OUTFLOW FROM THE MORNING AND AFTERNOON
CONV DIMINISHES THE INSTABILITY SOMEHWAT. SO WILL LEAVE OUT ANY
TEMPO GROUPS OF CONV IN THE LATER TAF PERIODS.

&&

.PREV DISCUSSION... /ISSUED 428 AM CDT SAT AUG 30 2014/

SHORT TERM /NOW THROUGH SUNDAY/...THE ATMS OVER THE AREA REMAIN
PRETTY MOIST AND UNSTABLE AS DEEP LAYER TROPICAL MOISTURE REMAINS
ENTRENCHED OVER THE AREA. THE 00Z BRO SOUNDING REMAINS PRETTY MOIST
AND UNSTABLE WITH A PWAT AROUND 2.4 INCHES AND A CAPE AROUND 2930
J/KG. THIS DEEP LAYER MOISTURE WILL INTERACT WITH THE 500 MB
INVERTED TROUGH AXIS OVER THE AREA TO INITIATE CONV THROUGHOUT THE
MORNING AND AFTERNOON HOURS. KBRO RADAR HAS SHOW A STEADY INCREASE
IN THE CONV COVERAGE OVER THE LAST SEVERAL HOURS. THE INVERTED 500
MB TROUGH WILL DRIFT SLOWLY WESTWARD TODAY AND TONIGHT AND WILL THEN
START TO WEAKEN SOMEWHAT LATE SUNDAY. THE DEEPER LAYER MOISTURE
LEVELS ALSO START TO DIMINISH SOME LATE IN THE DAY SUNDAY. THIS
SHOULD ALLOW FOR A LITTLE LESS CONV COVERAGE TOMORROW.

THE SHORT RANGE MODELS SHOW PRETTY GOOD AGREEMENT IN POPS FOR TODAY
AND TONIGHT AND THEN START TO DIVERGE ON SUNDAY WITH THE ECMWF AND
GFS GUIDANCE DRYING OUT THE MOISTURE LEVELS QUICKER THAN THE NAM
GUIDANCE WHICH MAINTAINS HIGHER POPS ON INTO SUNDAY. WILL LEAN
TOWARDS A BLEND OF THE MODEL POPS ESPECIALLY FOR SUNDAY AS AM A
LITTLE LEARY OF DROPPING THE POPS TOO QUICKLY IN LIGHT OF THE RECENT
SLOW MOVEMENT OF THE MID LEVEL TROUGH.

FOR TEMPS...THE NAM GUIDANCE IS THE COOLEST OF THE MODEL SETS SINCE
IT HOLDS ONTO THE HIGHER POPS THE LONGEST WITH THE MAV AND ECMWF
SHOWING CLOSER AGREEMENT. WILL LEAN CLOSER TO A MAV/ECMWF BLEND
SINCE THE MET TEMPS LOOK TO BE THE ODD MODEL OUT.

CONCERNING FLOODING POTENTIAL FOR THE AREA. SO FAR THIS MORNING THE
CONV HAS BE SCATTERED OUT ENOUGH AND FAIRLY QUICK MOVING TO KEEP
RAINFALL TOTALS SO FAR FAIRLY LOW. SO WILL NOT POST ANY FLASH FLOOD
WATCH AT THIS TIME BUT WILL MAINTAIN A MENTION OF LOCALLY HEAVY
RAINFALL POSSIBLE FOR TODAY. ANY FLOODING THAT MAY OCCUR WILL LIKELY
BE THE MINOR NUISANCE TYPE WHICH CAN BE COVERED BY FLS`S.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY NIGHT/...RAIN CHANCES
DECREASE SLIGHTLY FOR MONDAY AS THE MOISTURE CONTENT DECREASES AND
THE 500MB RIDGE ELONGATES ACROSS THE REGION. WILL MAINTAIN A
SLIGHT CHANCE OF COASTAL MORNING ACTIVITY AND SEA BREEZE
CONVECTION MONDAY DUE TO THE DEEP EASTERLY FLOW. AN UNSETTLED
WEATHER PATTERN BEGINS TO DEVELOP ACROSS THE AREA TUESDAY THROUGH
FRIDAY AS A TROPICAL WAVE MOVES INTO THE BAY OF CAMPECHE TUESDAY
AND WEDNESDAY. THE LATEST CMC/ECMWF/GFS AND NAM ARE IN BETTER
AGREEMENT AND INDICATE THAT A WEAK SURFACE LOW WILL DEVELOP ALONG
THE TROPICAL WAVE AS THIS FEATURE MOVES TOWARDS VERACRUZ MEXICO.
RAIN CHANCES BECOME PROBLEMATIC BY MID WEEK...IF WEAK LOW PRESSURE
DEVELOPS AS MOST OF THE MOISTURE COULD REMAIN SOUTH OF THE RIO
GRANDE VALLEY AND DEEP SOUTH TEXAS. KEPT MOST OF THE PREVIOUS
FORECAST POPS INTACT AS MODELS KEEP DEEP TROPICAL MOISTURE ACROSS
THE AREA THROUGH FRIDAY. PRECIPITABLE WATER VALUES BEING TO
DECREASE ACROSS THE REGION FRIDAY NIGHT INTO NEXT WEEKEND. PLEASE
REFER TO THE LATEST STATEMENTS AND OUTLOOKS FROM THE NATIONAL
HURRICANE CENTER CONCERNING THIS SYSTEM. TEMPERATURES WILL REMAIN
BELOW NORMAL WEDNESDAY THROUGH FRIDAY COURTESY OF THE INCREASE
CLOUD COVER AND RAIN CHANCES.

MARINE...NOW THROUGH SUNDAY...CURRENTLY SURFACE OBS AND BUOY DATA
SHOWS A LIGHT TO MODERATE SOUTHERLY SURFACE FLOW CONTINUING OVER
THE BAY AND GULF WATERS EARLY THIS MORNING WITH OFFSHORE SEAS
HOLDING AROUND 3 FEET. A LIGHT TO MODERATE SOUTH TO SOUTHEAST
SURFACE FLOW WILL LIKELY PERSIST INTO SUNDAY AS THE PGF REMAINS
FAIRLY WEAK. THIS SHOULD KEEP THE BAY AND GULF CONDITIONS WELL BELOW
SCA CRITERIA THROUGHOUT THE WEEKEND.

SUNDAY NIGHT THROUGH WEDNESDAY NIGHT...HIGH PRESSURE ACROSS THE
NORTHERN GULF WILL MAINTAIN LIGHT TO MODERATE WINDS AND MODERATE
SEAS THROUGH MONDAY. THE PRESSURE GRADIENT BEGINS TO STRENGTHEN BY
TUESDAY AS HIGH PRESSURE OVER THE NORTHERN GULF INTERACTS WITH A
TROPICAL WAVE ACROSS THE SOUTHWEST GULF. SMALL CRAFT ADVISORIES
MAY BE NECESSARY BY LATE TUESDAY DUE TO INCREASING WINDS AND SEAS.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  90  80  90  81 /  60  30  30  10
BROWNSVILLE          91  78  93  78 /  60  30  30  10
HARLINGEN            92  77  94  77 /  60  30  30  10
MCALLEN              94  78  96  78 /  60  30  30  10
RIO GRANDE CITY      95  79  98  79 /  30  20  30  10
SOUTH PADRE ISLAND   88  80  88  80 /  60  30  40  10

&&

.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
GRAPHICAST/UPPER AIR...58




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