Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 182323

Area Forecast Discussion
National Weather Service Brownsville TX
623 PM CDT Wed Oct 18 2017

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


.AVIATION...VFR conditions are expected overnight and into
Thursday. Similar to this morning, there could be some brief
visibility reductions early Thursday where we may flirt with MVFR
conditions at times. Conditions will quickly improve by
mid-morning. Surface winds will be light and variables through
this cycle.



.PREV DISCUSSION... /issued 248 PM CDT Wed Oct 18 2017/

SHORT TERM (Tonight through Thursday Night): Although somewhat
difficult to discern with absolute certainty, there doesn`t appear
to be much convective activity over the Gulf today. The GFS attempts
to bring low end pops toward the coast overnight, but it is less
bullish than a day ago. The ECMWF is not as aggressive, but it does
bring some pops into the coastal areas Thursday night. With PWat
values forecast to stay around an inch and continuing drier air in
the mid levels, rain doesn`t look to be a guarantee. Thus, kept pops
on the conservative end rather than buy off on the more aggressive
model blends, holding things to isolated showers over the Gulf and
no mentionable pops over land.

Otherwise, temperatures will continue to modify with the main high
pressure area to the northeast, shifting east. Winds will very to
east but will remain light through the short term. Dew points will
creep up into the mid 60s near the coast, and overnight low
temperatures may be still just low enough to support patchy fog
across the CWA. Most areas reported light fog this morning, and
would expect the same Thursday morning, so went ahead and put it in
the forecast for a few hours. High temperatures on Thursday will be
well into the 80s, with low temperatures  Thursday night in the
upper 60s to near 70.

The long east fetch developing on Thursday will build swells
Thursday night and into the long term. Not sure whether there will
be significant beach runup Thursday night, but it will be something
to keep an eye on, especially moving into the long term.

LONG TERM (Friday through Wednesday):
Going into the weekend, the H5 ridge will be pushing east as the
large scale trough moves ashore on the west coast, with the
leading edge sweeping through Texas. As the trough sweeps across
the US, it will begin to amplify and stretch across the central
US, trying to cutoff towards the lower Mississippi Valley later
Sunday. At the surface, Return flow will be continuing as surface
low pressure begins to build and sweep across Texas Sunday. Some
llvl moisture will be available ahead of the front, but will be
limited to very close to the surface. This will keep rain chances
very low, but a streamer shower would not be out of the question.
Models have again become more optimistic with rain chances with
the front, mainly Sunday afternoon and evening. With the H5 trough
moving east Monday, northwesterly flow behind the trough will
help keep the front moving southeastward, so drier air will
quickly infiltrate the region, allowing for cooler lows Sunday
night. Northerly flow continues through the first half of the
week, with a secondary area of high pressure moving into Texas
later Tuesday.

Now through Thursday Night: High pressure will shift east and
winds will veer to east and strengthen. The long east fetch across
the Gulf will drive slightly higher wave heights from Thursday
night into the long term. Northeast winds will be moderate to
fresh Thursday night and wave heights may sneak up to seven feet
offshore, into low end small craft advisory territory.

Friday through Sunday: Onshore flow remain modest Friday with high
pressure to the northeast, but the flow around the ridge will be
across most of the Gulf, so higher long period swells will be
continuing through the day and into Saturday. Conditions improve
briefly on Sunday morning, before the next cold front sweeps
through the region later Sunday afternoon. Gusty winds behind the
front will again push seas upwards, reaching near 7 feet Monday




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