Area Forecast Discussion
Issued by NWS Brownsville, TX

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531
FXUS64 KBRO 292344 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
544 PM CST Tue Nov 29 2016

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

&&

.AVIATION...A cold front moving through South Central Texas will
get here overnight, likely moving through just before dawn and
before the early flights. Light fog and lower ceilings may set up
tonight ahead of the front, and some low clouds may linger in its
wake, but by 12z moderate, gusty northwest winds will be in force
with decks lifting and VFR conditions at MFE and HRL, though
possibly not quite at BRO.

&&

.PREV DISCUSSION... /issued 255 PM CST Tue Nov 29 2016/

SHORT TERM (Tonight through Wednesday Night):
First of two surface boundaries to affect the area in short-term has
moved into MFE during the past hour with wind-shift to NW.  No
cooling to speak of, though, as temp still 93F there so will at
least tie the daily record; HRL has already broken its record for
today.

A second, more bona-fide cold front will move through Deep South
Texas and the Rio Grande Valley during the pre-dawn hours of
Wednesday, reaching the northern Ranchlands about 06Z and the RGV
between 09-12Z. Breezy to gusty northerly winds will prevail across
the region on Wednesday in the wake of the front. Moisture will be
lacking, though, so not expecting any precip. Knocked 2-4 degrees F
off of tonight`s min temps with less cloud cover expected and cold-
air advection looking slightly better in latest model runs.  Dry air
will be in place by late morning on Wednesday allowing high
temperatures to recover to the mid to upper 70s (pretty close to
normal) under mostly sunny skies.

Winds gradually veer to the ENE and slacken tomorrow night as high
pressure settles over East-Central Texas.  With the dry air in
place, lighter winds, and clear skies, min temps Thursday morning
will range from near 60F near the coast to the upper 40`s over
Zapata and Jim Hogg counties...again, actually pretty close to
normal though it will feel quite cool.

LONG TERM (Thursday through Tuesday): Thursday will start with
the return flow back into the region, bringing slightly more
moisture at the surface and moderating the temperatures back into
the upper 70s and lower 80s. Friday through the weekend is still a
considerable forecasting dilemma, as minor differences in each
model and run-to-run differences are producing wildly different
forecast solutions for Deep South Texas. All the models have begun
to come together closer to the slower solution noted the previous
couple days, with the H5 low now being cut off by all models in
northwest Mexico. The issue now is that the models are slightly
more to the west with the cutoff low, which in turn, induces the
surface trough further west, setting up just inland from the
coast. This has the effect of decreasing the amount of overrunning
for the valley, shifting better overrunning further north. With
this surface feature continuing to vary slightly, will hold onto
PoP chances for Friday and Saturday until the feature location
becomes more consistent. The cutoff low begins to eject across
Texas Sunday night into Monday. The location and timing of the
ejection has subsequent bearing on the surface trough and it`s
departure. Staying with the slower of the model runs, the trough
should wrap up and move northeast during the day Sunday,
strengthening the overrunning in the region for the day. Rain
chances thusly have increased for the latter half of the weekend.
Monday rain chances depend highly on how fast the surface low
exits the region, with the faster models drying things out quickly
Monday morning and the slower models hanging on to chances for
light rain and cloudy conditions through the afternoon. Since
there is some threat for rainfall, have kept rain chances through
the day Monday before coming to an end Monday evening.

MARINE:
Now through Wednesday night: As of 150 PM, Buoy 020 reporting
southerly winds around 18 knots with seas of 7 ft. Winds and seas
have been slower to subside than expected, but with the near-term
downward trend finally beginning, will go ahead and let the
current Small Craft Advisory expire at 3pm as seas should trend
below 7 ft. very soon.

The passage of a cold front in the wee hours Wednesday will generate
strong northerly winds in its wake.  Winds will quickly increase
into the 20-28 knot range across all of the coastal waters in the
wake of this front.  A brief period of isolated gale-force gusts are
also possible for a few hours with the passage of the cold front,
but confidence is lacking for a Gale Watch or Warning at this time.
After coordination with CRP, will be issuing a new set of SCA`s
shortly commencing at 09Z on Thursday. For now will run them through
18Z for the Laguna Madre and 00Z Friday for the Gulf waters since
seas will build to 8-10 ft. Wednesday morning and will only
gradually subside through the remainder of the day.  A SCA for
Hazardous Seas may be needed into tomorrow evening.

Thursday through Sunday: Conditions over the weekend will be
agitated by the developing coastal trough across the region.
Modest onshore flow will continue around the trough through the
weekend, starting from the east and gradually shifting from the
north by Sunday morning. Seas will be highly agitated, with long-
fetch seas running 4 to 6 feet throughout the forecast period.
Rainfall is expected area wide Friday through Sunday, with the
focus on Friday night and Sunday morning.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory for winds from 3 AM to noon CST Wednesday
     for GMZ130-132-135.

     Small Craft Advisory from 3 AM to 6 PM CST Wednesday for GMZ150-
     155-170-175.

&&

$$

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