Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 231139 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
639 AM CDT TUE AUG 23 2016

.DISCUSSION...Updated for latest aviation discussion below.

&&

.AVIATION...Mostly clear skies and light southeast winds prevail
across deep south Texas this morning. VFR conditions expected to
continue through the next 24 hours as a 500mb ridge builds
overhead and provides subsidence across deep south Texas. Light
southeast winds this morning will become breezy mid to late
morning. Winds will gradually diminish to around 10 knots by late
this evening.


&&

.PREV DISCUSSION... /issued 435 AM CDT TUE AUG 23 2016/

SHORT TERM (Today through Wednesday): Brownsville radar shows a few
showers across the Gulf waters this morning. This activity is due
some lingering moisture and weak instability off the lower Texas
coast. These showers are moving to the northwest and should begin to
diminish after sunrise. Water vapor imagery indicates an east to
west elongated 500 mb ridge over the northern Gulf of Mexico this
morning. This mid to upper level ridge will continue to build over
the region through the forecast period. This will result in hot, dry
and breezy conditions for today and Wednesday. High temperatures
today and Wednesday will be slightly above normal under mostly sunny
skies. Clear skies and light winds are expected tonight with low
temperatures generally in the upper 70s.

LONG TERM (Wednesday Night through Monday): 500 mb ridging will
prevail over the Gulf of Mexico and the southeastern U.S. for Wed
night and Thurs. This 500 mb ridging then gradually shifts north
and northeast as troffing deepens over the central and western
states. Deep layer moisture values then start to move into Deep
South TX from a couple of directions. The first being tropical
moisture starting to advect west and north around the periphery of
the ridge. The second being some better moisture values advecting
steadily east and northeast from central Mexico. As the deeper
moisture values start encroaching into the region and the 500 mb
ridge shifts farther away from the RGV expect the conv potential
to build gradually over the region.

With the tropical moisture values building over the region and the
500 mb ridging gradually lossing its grip over the RGV expect
temps to lower a bit late in the forecast period. The ECMWF and
GFS are in reasonable agreement for maxes and mins through the
longer term.

The ECMWF is a little wetter through day 7 versus the GFS since
the GFS is less aggressive with the moisture advection. Will opt
for a longer range model blend for pops and temps. The run to run
consistency with the GFS MEX guidance is pretty stable for temps
and pops. The 500 mb heights from the GFS and ECMWF are in pretty
decent agreement through day 7.

Overall confidence is above average for the longer temps and only
closer to average for pops due to the greater differences in the
model pops.

Tropics...Much of the longer range numerical guidance for tropical
invest AL99 places this system near Florida by Mon/Tues of next
week. NHC gives this tropical wave a 60% chance of development
into a tropical cyclone over the next 5 days. Please refer to the
latest statements and outlooks from NHC concerning the progress of
this system.

MARINE  (Now through Wednesday): Buoy 42020 reported southeast winds
around 16 knots gusting to near 19 knots with seas around 3.3 feet
with a period of 6 seconds at 300 AM CDT/08 UTC. Surface high
pressure across the Gulf of Mexico will maintain generally light to
occasionally moderate southeast winds and low to moderate seas along
the lower Texas coast through Wednesday.

Wednesday night through Saturday night: Surface ridging over the
Gulf of Mexico will gradually give way to broad surface troffing
over the Gulf as the 500 mb ridge moves farther north. This will
allow a light east to northeast flow to develop along the lower TX
coastline from Thursday on through Saturday night. The light
surface flow will allow low seas to prevail. No SCA conditions
expected through Saturday night.

&&

.BRO Watches/Warnings/Advisories...
TX...None.
GM...None.
&&

$$

This product is also available on the web at:
HTTP://WEATHER.GOV/RGV

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