Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 191744
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1244 PM CDT Sun Mar 19 2017

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

&&

.AVIATION...Mostly/all VFR conditions expected for the next 24
hours at the RGV airports.  Moderate winds have acquired a more
southerly component instead of SE early this afternoon. Cumulus
field already starting to thin out per visible satellite imagery.
This trend should continue over the next few hours as dry air
aloft beneath the high mixes down, with clear/mostly clear skies
expected by 21Z. Even with high pressure surface and aloft
continuing to dominate the weather pattern, will lean less on
persistence and more toward guidance by forecasting prevailing
VFR conditions for the evening and on into the early morning
hours. Very dry air aloft is progged to move into the eastern half
of the CWA (encompassing the terminals). Also, the surface high
centered over the west-central Gulf currently will be nudged a
bit eastward, tightening the pressure gradient, which will keep
wind speeds up around 8+ knots through the night. Prog soundings
show an inversion forming up around 015-020. Given all of this,
think that fog/low stratus formation will be greatly inhibited, so
will include only SCT low decks at this time. VFR continues with
breezy winds returning mid-late morning on Monday.

&&

.PREV DISCUSSION... /issued 631 AM CDT Sun Mar 19 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Areas of MVFR fog have developed at TAF locations
early this morning, with a low cloud deck bringing MVFR to LIFR
cigs. Conditions should improve rather quickly through the morning
as very dry air mixes down as surface heating starts. VFR
conditions with some gusty SE winds will prevail through the
afternoon, with winds decreasing this evening and potential low
clouds forming again early Monday morning.

PREV DISCUSSION... /issued 432 AM CDT Sun Mar 19 2017/

SHORT TERM (Today through Monday): Some patchy fog and low clouds
will continue through the overnight hours. High pressure aloft and
over the Central Gulf will continue to dominate the weather pattern
today and Monday. As such, it will be another warm, spring-like day
to round out the weekend, with highs a degree or two warmer then
yesterday. There is plenty of dry air to mix down and do expect
partly to mostly sunny conditions and the occasional higher wind
gust. As far as the beaches go, southeast swells are still slightly
elevated, and given the likelihood for crowded beaches, will go with
a Moderate Risk today. For Monday, the winds maybe a bit breezier as
the pressure gradient once again begins to tighten as low pressure
begins to deepen in the Panhandles region. Meanwhile, the warming
trend will continue as dry conditions remain in place.

LONG TERM (Monday Night through Saturday): 500 mb ridging will
dominate the south central Plains through Thurs maintain steady
low level WAA and elevated 1000-500 mb thicknesses. Then on Thurs
Night and Fri a deep 500 mb trough axis will dig across the
southern Plains states pulling a weak cold front through the
region late Fri night into early Sat. CAA does not look very
strong with this fropa with mainly drier air working its way into
the RGV lowering overnight lows a bit.

Overall moisture advection over the RGV appears to remain pretty
limited late next week. So will only mention some slgt chc pops
with the passage of the 500 mb trough and the associated cold
front.

The GFS and ECMWF models remain in pretty good agreement in the
placement of the 500 mb fields through Day 7 and accordingly show
decent agreement for both the temps and pops. The ECMWF has a
little bit of a warmer bias late in the forecast period versus the
GFS. The GFS MEX MOS temps and pops show good run to run
consistency over the last several days. So overall confidence in
the longer range forecast wording remains above average today.

MARINE (Now through Monday): High pressure remains in control of
the Gulf with Buoy 42020 reporting SSE winds at less than 10KTS and
seas between 3 to 4 feet as of 3 AM. Excellent marine conditions are
expected today with light to moderate S to SE winds and low to
moderate seas. The pressure gradient will tighten on Monday as high
pressure over the Gulf begins to interact with a deepening low
pressure system near the Panhandles Region. This will increase winds
across the Laguna Madre and SCEC conditions could develop.

Monday Night through Thursday Night: Surface ridging over the Gulf
of Mex will maintain light to moderate S-SE surface winds across
the lower Texas coastline into next week. Later next week as the
500 mb trough and associated cold front approaches from the
west...the PGF will start to strengthen on Thur possibly pushing
the S-SE surface flow and Gulf swells up to SCA levels late in the
CWF period.

&&

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

$$

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