Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 161129 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
529 AM CST Thu Nov 16 2017

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

&&

.AVIATION...Surface observations indicate fog is expanding across
the Rio Grande Valley with visibilities briefly dropping to 1
mile at times at HRL and MFE. Have kept IFR TEMPO groups in
through sunrise for low ceilings and visibilities due to satellite
trends. By mid-morning, conditions should improve with daytime
heating and winds increasing out of the southeast. This afternoon,
a few showers will be possible mainly in the vicinity of the BRO
and HRL airports, but VFR categories are expected through the day
as moisture depth is limited vertically.

A very dry layer just off the moist surface will possibly bring
another round of fog tonight into Friday morning. However,
slightly higher winds should keep fog from becoming dense or
widespread.

&&

.PREV DISCUSSION... /issued 423 AM CST Thu Nov 16 2017/

SHORT TERM (Now through Friday): Satellite imagery and surface
observations indicate fog is trying to develop early this morning,
but it is having trouble due to a stratus deck expanding across much
of the middle valley and northern ranchlands. A few areas could
still see patchy fog with reduced visibilities through mid morning
when daytime heating and winds are expected to increase. Later this
morning and afternoon, conditions will improve with scattered clouds
and another day of above-normal temperatures. Mid-level high
pressure still is the dominant feature across South Texas, keeping
the area mostly rain-free. At the surface, though, weak troughing of
low pressure along a dissipating front will provide an opportunity
for isolated showers along the coast and over the marine areas
today. Weak surface flow and warm temperatures may allow a weak
seabreeze to push a couple showers further west, but most areas
should remain dry as moisture is limited above the 850mb layer.

Friday, another round of fog and low clouds will be possible in the
morning as strong subsidence continues above a moist surface. The
winds may be a bit higher overnight, so not expecting widespread
dense fog at this time. In the afternoon, dry conditions and very
warm temperatures are expected again with highs ranging from the mid
80s east and low 90s in the Upper Valley, which may near record
levels. Winds will increase in the afternoon with gusts around 20
mph as the next storm system develops in the Central Plains.

LONG TERM (Friday Night through Wednesday): Saturday remains the
target day for the passage of a cold front. Isolated showers now
appear to be most likely along and east of the Interstate 69E
corridor Saturday afternoon through Saturday night, where
precipitable water values will be greatest. The passage of the
cold front will also serve to bring daytime high and overnight low
temperatures to more near normal levels after above normal values
Friday night and Saturday. 500 mb high pressure centered near the
Baja Peninsula and a mid-level flow out of the northwest and north
in the wake of the cold front will ensure dry weather for the
entire BRO CWFA Sunday through Wednesday.

MARINE (Now through Friday): Light to moderate southeast winds and
seas at 2 to 3 feet will continue today with surface high pressure
over the eastern U.S. and a weak pressure gradient. Low pressure
will develop in the Central Plains on Friday, which will increase
winds to 15 to 20 kts Friday night. Seas will also build to 4 feet
by the end of the short term period.

Friday Night through Wednesday: The early Saturday night passage
of a cold front through the Lower Texas coastal waters will
generate Small Craft Advisory winds and/or seas early Saturday
night through Sunday night. Ahead of the front, Small Craft
Exercise Caution winds and/or seas are possible for portions or
all of the Lower Texas coastal waters Friday night and Saturday.
After Sunday night, much more favorable winds and seas are
anticipated.

&&

.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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