Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 160602 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
102 AM CDT Tue May 16 2017

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


.AVIATION...MVFR ceilings will prevail for much of the next 12
hours, though they have risen to low-end VFR at MFE currently, as
robust, moist SE flow continues. Pressure gradient will generate high-
end breezy winds by mid-morning, lasting into the evening, though
latest guidance has backed off some on wind speeds from previous
solutions. Winds gusts will peak at 30-35KT, but not expecting AWW
criterion to be met for BRO/HRL for any significant length of
time. Ceilings may also lift back up to VFR via mixing and
associated raising of inversion height this afternoon, but
confidence on timing fairly low at this time. MVFR CIG`s
anticipated to redevelop at all TAF sites after sunset Tuesday.


.PREV DISCUSSION... /issued 631 PM CDT Mon May 15 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...MVFR ceilings will develop at all TAF sites this
evening and will persist through much of Tuesday. The other issue
will be wind. Breezy to windy conditions will develop Tuesday,
especially along the coast, thus impacting BRO and HRL most. Gusts
to 35 knots will be possible. The stronger winds will mix out low
clouds to some extent, but higher ceilings, if they are able to
lift to VFR, may remain transient and limited.

PREV DISCUSSION... /issued 303 PM CDT Mon May 15 2017/

SHORT TERM (Tonight through Tuesday Night):Deep South Texas will
be between the subtropical ridge over the Western GOM and NE
Mexico and a shortwave trough moving across the SW Deserts. Low
level moisture, albeit currently shallow, will be increasing over
the next 24-36 hours as the southerly flow strengthens. Tonight
we will continue to see clouds thicken and lower as the surface
base inversion strengthens. Warm and humid with a moderate breeze
anticipated. Tuesday still looks rainfree but dew points will be
increasing along with the wind as the pressure gradient strengthens
as surface pressures fall over West Texas. GFS guidance remains
bullish showing winds approaching wind advisory within our wind
corridor between the interstates 69C and 69E. Not all that
confident to issue a wind advisory at this time and will let the
overnight crew view the 00Z model package. As for temperatures
highs still ranging about 3 to 5 degrees above normal even with
the cloud cover but ovenight lows Tuesday night will be 6 to 8
degrees above normal with clouds and wind prevailing.

LONG TERM (Wednesday through Monday): Models are in fair
agreement and consistency with the mid level flow while the
surface features are also in decent agreement until near the end
of the forecast period. The most interesting day of the period
looks to be Wednesday as a moderately sharp shortwave trough
passes to the northeast of the forecast area. At the surface a
surface trough/dryline over SW TX/NE Mexico drifts eastward into
our western areas of the CWA winds turn northwest to north with
compressional heating to take place. Morning clouds to quickly
dissipate and temperatures to increase through the afternoon as
dew points drop. Held onto the previous forecasters high temps
(which are above guidance) with only a few minor adjustments in
the east where the dryline is not expected to reach and clouds
should hang on much of the day. The clouds and added moisture in
the eastern third of the region look to combine with the tail end
of the upper trough and a possible sea breeze to at least
initiate a slight chance of showers or thunderstorms.

As the shortwave passes to the east Wednesday broad Southwest flow
to dominate the rest of the period as a large scale upper
trough/low strengthens over the Rockies. This trough works its way
through the plains next weekend with some timing and placement
differences of a cold front. This will play havoc on rain chances
Saturday night through Monday with plenty of uncertainty and day
to day changes among the models. Have played down the chances
slightly and have gone broad brush slight chances (20%) at this
time. Temperatures will not see much variation until late in the
weekend and early next week with very warm overnight lows and
slightly above normal highs.

MARINE: Tonight through Friday...Pressure gradient increases
tonight through Tuesday night as a shortwave trough advances into
West Texas. Exercise caution conditions tonight will likely be
upgraded to small craft advisories Tuesday as the gradient peaks.
A surface trough moves into the Rio Grande Plains Wednesday with a
temporary weakening of the gradient at least for Wednesday
afternoon and evening. Broad upper level trough strengthens over
the Rockies Thursday and Friday with surface pressures lowering
over the Southern Plains. A moderate to strong southeast flow
ensues with seas building. Periodic small craft advisory
conditions are anticipated for the end of the work week.




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