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FXUS64 KBRO 201140 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
640 AM CDT Wed Sep 20 2017

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

&&

.AVIATION...Periodic low clouds and streamer showers will continue
to move off the Gulf waters through the morning hours. Otherwise,
high pressure will remain in control of the weather over Deep
South Texas today, with isolated to scattered convective activity
possible. Southeasterly winds will become gusty this afternoon
with winds dropping off after sunset.

&&

.PREV DISCUSSION... /issued 430 AM CDT Wed Sep 20 2017/

SHORT TERM (Today through Thursday): There will be a sense of
weather deja vu today as the warm and humid air mass remains in
place with high pressure ridging aloft. With this consistent of
a pattern, have not made many appreciable changes to the forecast
today. As such, above normal temps will continue across the
region this afternoon, with values once again nearing or exceeding
the century mark for McAllen and areas along and west of the
I-69C/HWY 281 corridor, with values in the mid to upper 90s
eastward. Meanwhile, isolated to scattered convection will be
possible with any seabreeze initiation given PWATS around 2.0".

For Thursday, the pattern begins to shift a little as the
subtropical ridge flattens and elongates over the Texas and the
Gulf. As this occurs, a lobe of low pressure will stretch across the
northern Gulf coast with an uptick of moisture possible across the
Texas Coastal Bend region. Precip should be a bit more scattered to
possibly widespread and have upped POPs a bit by Thursday afternoon,
mainly across the offshore waters and northern coastal areas. Temps
should edge downward a degree or two across the eastern counties.

LONG TERM (Thursday Night through Tuesday): Major 500 mb
troffing digging over the western U.S. will build an elongated
ridge axis from the south central U.S. through the northeastern
states. This will maintain above normal temps into this coming
weekend. The western trough axis then digs further south and east
which will in turn shift the eastern ridging closer to the East
Coast. AS the western trough digs further east it will tap into
the deeper tropical moisture located over central and southern
Mexico and will start advecting it northwards. Most of this better
moisture appears to be shunted just to the west of the RGV.
Accordingly both the ECMWF and the GFS tend to hold the conv pops
down in the 20 to 30 % range through day 7.

Expect fairly status quo temps initially in the longer range
period with the overall temps dropping a bit latter in the period
as the ridge axis looses some of its grip over the region. So will
go at or above model guidance for high temps and close to a model
blend of the ECMWF and GFS numbers for lows.

MARINE: (Now through Thursday): Overall good marine conditions will
continue through the next 36 hours with broad surface high pressure
over northeastern Gulf of Mexico. A generally weak surface pressure
gradient will  maintain light to moderate southeast winds and low to
moderate seas through the period. Meanwhile, increased showers or
storm will be possible on Thursday.

Thursday Night through Sunday Night...Persistent surface ridging
over the eastern States will maintain light to moderate SE winds
and pretty benign seas through Sunday. No SCA conditions expected.

&&

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

$$

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