Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 251131
AFDBRO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
631 AM CDT MON AUG 25 2014

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

&&

.AVIATION...VFR CONDITIONS HOLDING THROUGHOUT THE AREA AND SHOULD
THROUGH THE REMAINDER OF THE TAF PERIOD ALTHOUGH SCATTERED CLOUDS
AROUND 2000 FT WILL BE POSSIBLE FOR ANOTHER TWO TO THREE HOURS.
SEABREEZE FRONT WILL PICK UP WINDS OUT OF THE EAST LATE THIS
MORNING AND THIS AFTERNOON WITH WIND SPEEDS DECREASING AGAIN AFTER
SUNSET. THERE IS A SMALL CHANCE FOR SHOWERS TODAY BUT TOO LOW FOR
TAF MENTION AND THE CHANCE OF OPERATIONALLY SIGNIFICANT CONVECTION
APPEARS EVEN LOWER. /68-JGG/

&&

.PREV DISCUSSION... /ISSUED 404 AM CDT MON AUG 25 2014/

SHORT TERM /NOW THROUGH TUESDAY/...BROAD UPPER RIDGING CONTINUES
ALOFT AS DEEP SOUTH TEXAS SITS IN A FAIRLY THERMALLY UNIFORM
AIR MASS THAT IS A LITTLE LACKING IN MOISTURE DEPTH AND RICHNESS
THIS MORNING. AMSU/SSMI AND GOES SOUNDER DATA SUGGESTS THAT
DESPITE MODEST EAST TO NORTHEASTERLY FLOW AROUND 500/700MB THERE
STILL JUST IS NOT QUITE ENOUGH MOISTURE OVER THE WESTERN GULF OF
MEXICO TO SIGNIFICANTLY CHANGE OUR AIR MASS THROUGH ADVECTION. LOW
LEVEL PRESSURE GRADIENT IS LIGHT WITH WEAK RIDGING CENTERED
SOUTHWEST OF THE LOUISIANA COAST AND A LIGHT EAST TO SOUTHEAST
FLOW ACROSS MOST OF THE AREA. AN UPPER LEVEL LOW OVER
LOUISIANA/MISSISSIPPI IS HEADING THIS GENERAL DIRECTION BUT LIKELY
WON`T BEGIN TO SIGNIFICANTLY INFLUENCE AREA WEATHER FOR ABOUT
ANOTHER 24 TO 36 HOURS.

TODAY...LIGHT ONSHORE WIND REGIME WILL BE CONDUCIVE TO A STRONGER
SEA BREEZE GRADIENT TODAY AND THE ONSHORE FLOW WILL LIKELY KEEP
TEMPS A DEGREE OR TWO COOLER THAN YESTERDAY FROM HIGHWAY 281
EAST. LOW LAYER MOISTURE DEPTH/RICHNESS DOES NOT APPEAR TO BE
PARTICULARLY CONDUCIVE FOR DEEP CONVECTION TODAY. ALTHOUGH IT IS
NOTED THE NAM DOES SHOW A LITTLE BETTER MOISTURE OVER THE VALLEY
AND NAM AND THE ARW/NMM MESOSCALE MODELS DEVELOP AN AREA OF
CONVECTION WEST OF HIGHWAY 77 IN THE AFTERNOON. PRESENT WX/CLOUD
COVER AND AMSU/SSMI TOTAL PRECIPITABLE WATER ESTIMATES LEND SOME
CREDIBILITY TO THAT SOLUTION AND DEPICTED A SLIGHT CHANCE OF
SHOWERS/20 PCT BASICALLY IN BETWEEN HIGHWAY 77 AND 281 IN THE
SOUTHERN HALF OF THE CWA. COVERAGE/INTENSITY SHOULD BE ABOUT LIKE
TODAY WHERE A FEW CU MANAGE SOME SPRINKLES OR A BRIEF MODERATE
SHOWER.

TONIGHT...UPPER LEVEL LOW WILL BEGIN TO APPROACH BUT LIKELY NOT
QUITE COME CLOSE ENOUGH TO SIGNIFICANTLY CHANGE OUR MID LEVEL
LAPSE RATES/PRODUCE SIGNIFICANT LIFT BUT THERE SHOULD BE ENOUGH
INSTABILITY OVER THE WARMER GULF WATERS BEYOND 5 TO 10 NAUTICAL
MILES TO SPARK A FEW SHOWER AND POSSIBLY A THUNDERSTORM OVERNIGHT.
WIND REGIME OVERALL WILL BE VERY LIGHT AND WINDS COULD GO CALM IN
THE LATE OVERNIGHT AMID THE TYPICAL WARM AND SOUPY OVERNIGHT LOW
TEMPERATURES.

TUESDAY...BETTER MID LEVEL LIFT WILL BE MOVING INTO THE COASTAL BEND
REGION AND SLIGHTLY BETTER MOISTURE OVER THE NORTHERN HALF OF THE
CWA MAY WORK WITH LATE AFTERNOON SEA BREEZE TO PRODUCE A FEW ISOLATED
THUNDERSTORMS. ADDED A 20 PCT/SLIGHT CHANCE OF SHOWERS/STORMS MAINLY
IN THE TYPICAL FAVORED RAYMONDVILLE/SARITA/FALFURRIAS TRIANGLE IN
THE AFTERNOON AND KEPT MAX TEMPS SIMILAR TO MONDAY. KEPT THE VALLEY
DRY FOR NOW WITH THE UPPER LEVEL LOW CENTER STILL SEVERAL HUNDRED
MILES TO THE NORTHEAST AND THE NAM/ECMWF/GFS ALL AGREEING ON KEEPING
THE BEST 850/700MB MOISTURE NORTHEAST OF THE CWA THROUGH THIS TIME
PERIOD. /68-JGG/

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...A 593 DAM HGT CENTER
OVER THE CENTRAL MS VALLEY AT GATE TIME WILL EXTEND SOUTHWEST OVER
NORTH TX. SURFACE HIGH PRESSURE ACROSS THE SOUTHEAST...UNDER THE
RIDGE...WILL DRAW MOISTURE ACROSS THE NORTHERN GULF COAST FROM THE
EAST...WITH A WEAK MID LEVEL LOW OVER THE NORTHWEST GULF. EVEN SOME
MID TO HIGH LEVEL MOISTURE MAY BE SIPHONED AWAY FROM CRISTOBAL...
AROUND THE SOUTHERN PERIPHERY OF THE RIDGE AND INTO THE GULF. THE
INFLUX OF MOISTURE WILL CAUSE LOCAL PWAT TO ROCKET UP TO AROUND TWO
INCHES WEDNESDAY WITH ENHANCED SEA BREEZE POTENTIAL FOR WEDNESDAY
AFTERNOON. UNSETTLED WEATHER WILL CONTINUE OVER THE NORTHWEST GULF
THURSDAY THROUGH SATURDAY. A MORE TYPICAL SOUTHEAST WIND WILL
STRENGTHEN TOWARD THE END OF THE WEEK AS A SHORT WAVE TROUGH DIGS
INTO THE SOUTHERN PLAINS...WITH THE ASSOCIATED PRESSURE FALLS HELPING
TO SET UP A GRADIENT INTERACTING WITH HIGHER PRESSURE IN THE GULF.
DRIER AIR REALLY WON`T HAVE A CHANCE TO FILTER BACK IN TO THE CWA
UNTIL SUNDAY WHEN THE MID LEVEL TROUGH AXIS CLEARS EAST TEXAS. THAT
BRIEF INTERLUDE WILL NOT LAST LONG HOWEVER...AS GULF HIGH PRESSURE
WILL SET UP AND KEEP PUSHING TROPICAL MOISTURE THIS WAY.

THUS...TUESDAY INTO WEDNESDAY WILL REFLECT A BIT OF A CHANGE...WITH
OVERALL MOISTURE SEEING AN UPWARD TREND. NOT ONLY WILL THE UPPER
WEAKNESS BE OVER THE NORTHWEST GULF...WITH LESS LOCAL INFLUENCE BY
SURFACE HIGH PRESSURE AND THE UNSETTLED WX CONDITIONS JUST TO THE
NORTHEAST...BUT A PROGRESSIVE SHORT WAVE TROUGH WILL MOVE EAST FROM
THE PACIFIC NORTHWEST AND INTO THE CENTRAL PLAINS...PUSHING A WEAK
COLD FRONT INTO THE SOUTHERN PLAINS MID WEEK TO LATE WEEK IN ADVANCE
OF THE BUILDING RIDGE OVER THE DESERT SOUTHWEST. SHOWER ACTIVITY
WILL INCREASE JUST TO THE NORTH OF THE CWA...BOTH OVER THE GULF AND
OVER LAND AREAS AS THE MINOR WEAKNESS ALOFT LIES OVERHEAD. A WEAK
SURFACE TROUGH WILL ALSO SET UP JUST TO THE EAST OF THE CWA OVER THE
GULF. MEANWHILE...THE SURFACE FRONT WILL PUSH INTO CENTRAL TEXAS
AROUND THURSDAY AND THURSDAY NIGHT. THE GFS AND ECMWF SEEM TO BE IN
A LITTLE BETTER AGREEMENT WITH THE PLAINS SCENARIO THIS MORNING. THE
GFS SEEMS A LITTLE DEEPER/FARTHER SOUTH WITH THE TROUGH THROUGH
SATURDAY NIGHT...BUT THE OVERALL EFFECT ON DEEP SOUTH TEXAS WILL NOT
BE THAT GREAT AS A RESULT OF THE DIFFERENCE...AND THUS HAD AVERAGE
CONFIDENCE OR BETTER IN USING A BLEND OF BOTH MODELS WHICH REFLECTED
SIMILAR WEATHER ELEMENTS THROUGH THE LONG TERM.

TEMPERATURES WILL CONTINUE ABOVE NORMAL WITH HEAT INDEX VALUES IN
THE 103 TO 108 RANGE EACH AFTERNOON. PWAT WILL BE ELEVATED AND
ENOUGH TO SUPPORT A DAILY SEA BREEZE ON WHAT WILL BE LIGHT TO MDT
WINDS. AVAILABLE LOW LEVEL MOISTURE WILL SUPPORT A MIX OF CLOUDS AND
SUN WITH SCT TO BKN LOW CLOUDS. OVERNIGHT LOW TEMPS WILL CONTINUE TO
BE IN THE 75 TO 80 DEGREE RANGE. GFS GUIDANCE CALLS FOR A CHANCE OF
RAIN THURSDAY THROUGH SATURDAY...WHILE THE ECMWF SPREADS IT OUT AND
GOES FOR A CHANCE TO LIKELY WEDNESDAY THROUGH SATURDAY OR SATURDAY
NIGHT. THE BOTTOM LINE IS THAT A FEW DAYS OF INCREASED POTENTIAL FOR
RAIN APPEAR TO BE ON THE WAY.

MARINE...
NOW THROUGH TUESDAY...FAVORABLE MARINE CONDITIONS ARE FORECAST
THROUGH TUESDAY WITH LIGHT EAST TO SOUTHEAST WINDS AND LOW SEAS.
SMALL ISOLATED SHOWERS WILL BE POSSIBLE THROUGH EARLY MONDAY
MORNING AND A LITTLE MORE COVERAGE OF SHOWERS AND POSSIBLY A
THUNDERSTORM OR TWO IS EXPECTED MONDAY NIGHT INTO TUESDAY MORNING
WITH A SMALL CHANCE FOR SHOWERS CONTINUING INTO THE DAY ON
TUESDAY.

TUESDAY NIGHT THROUGH FRIDAY...MID LEVEL RIDGING WILL INITIALLY
STRETCH FROM WEST TEXAS ACROSS THE MID MISSISSIPPI VALLEY TO THE MID
ATLANTIC COAST. A WEAK MID LEVEL LOW WILL BE SITUATED OVER THE NORTH
WEST GULF AND WILL DESTABILIZE CONDITIONS ENOUGH TO EXCITE ENHANCED
SHOWER AND TSTM ACTIVITY TO THE NORTH...WITH SOME OF THAT CONVECTION
POSSIBLY MOVING SOUTH TOWARD THE LOWER TEXAS COAST. A BROAD...FLAT
PRESSURE FIELD OVER THE GULF WILL OTHERWISE RESULT IN MAINLY LIGHT
TO MODERATE ONSHORE WINDS...WITH SOME DISRUPTION TO TYPICAL MODERATE
SOUTHEAST WINDS BY NORTHEAST OR EAST FLOW EARLY IN THE PERIOD. SEAS
SHOULD CONTINUE IN THE LOW TO MODERATE RANGE...MAINLY 2 TO 4 FEET
OFFSHORE...BUT MAY BUILD A FOOT TOWARD THE END OF THE PERIOD WITH
THE RETURN OF STRONGER AND MORE TYPICAL SOUTHEAST WINDS AS HIGH
PRESSURE...WEAKENED BY CRISTOBAL MOVING UP THE EAST COAST...MAKES A
COMEBACK INTO THE GULF.

&&

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

$$

THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
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