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465
FXUS64 KBRO 250547 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1247 AM CDT Tue Jul 25 2017

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

&&

.AVIATION...Small area of BKN cigs around 2500 drifting past KMFE
currently will quickly drift northward during the next hour.
Similar cigs may return briefly through the night, but will
quickly drift through. Increased moisture moving into the region
today will bring more CU during the day, but most areas will
remain SCT or better. A couple seabreeze showers are possible this
afternoon, but coverage too minimal to add in TAFs at this time.
Breezes will again rise after sunrise, but will not reach as high
as on Monday.

&&

.PREV DISCUSSION... /issued 704 PM CDT Mon Jul 24 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...High pressure remains in control over the Gulf, with
an induced mid-level trough overhead between height centers over
both the Southern Plains and the Eastern Gulf. Boundary layer
moisture will increase tonight, supporting low level clouds below
an inversion showing up on the forecast sounding. Sufficient
clouds could invoke MVFR conditions. This is best seen developing
around midnight, with a less convincing profile by Tues morning.
Model guidance increases cloudiness in general on Tuesday, but
with ceilings above 3 kft. Coastal showers and/or sea breeze
activity will be possible Tuesday, with the ECMWF guidance more
robust with rain chances than either the NAM or GFS. Besides the
weak mid-level trough aloft, the right entrance region of a jet
streak will be at least partially over the CWA Tuesday afternoon,
so won`t rule out a few rumbles of thunder with any convection
that develops.

PREV DISCUSSION... /issued 302 PM CDT Mon Jul 24 2017/

SHORT TERM (Tonight through Tuesday Night): Water vapor analysis shows
the H5 ridge centered over Southern NM/AZ this afternoon with a
deepening trough across the Eastern U.S. Meanwhile, a weak mid-level
trough axis is stretched across the Northern Gulf coast back into
Eastern Texas. This area of troughing will allow a weak mid level
wave to skirt across Northern Mexico overnight, bringing a small
plume of tropical moisture into the RGV. The atmosphere is dry,
however, and think that it will be mostly mid to upper level clouds
that move in initially. Should low level moisture increase enough
overnight and through the day Tuesday, isolated shower/storms could
be generated in the heat of the afternoon along any seabreeze that
develops. However, the ridge of high pressure will continue to bring
strong subsidence and current thinking is that overall coverage of
showers will remain low on Tuesday. As far as temps go, warm
overnight lows will remain in places. Highs on Tuesday should be a
degree or two cooler, however this will highly depend on
clouds/rainfall.

LONG TERM (Wednesday through Monday): Broad ridging over the
Southern Plains/North Texas will continue to dominate much of the
long term forecast as deep troughing occasionally digs into the
eastern U.S.. Model guidance, especially the ECMWF, continues to
keep rain chances in the forecast for Wednesday and Thursday as an
upper level low approaches northeast Mexico Wednesday afternoon.
Moisture will definitely be sufficient for at least isolated
convection, but confidence is too low to go any higher at this
time, so have kept the previous forecast more or less in tact. As
we move into the end of the week, ridging continues to build in
across Deep South Texas with strong subsidence persisting through
early Sunday. Temperatures will likely rise to near record levels
Friday and Saturday with highs well above 100F in the Upper
Valley and Ranchlands.

Sunday into Monday, a surface low pressure system associated with
the deep upper trough is progged to move into the Southeast U.S.,
bringing the hint of a weak cold front behind it into the
Southern Plains. Obviously this would be very rare for this time
of year, so confidence isn`t there yet with how far south it will
end up. Regardless, models indicate moisture increasing ahead of
it early next week, so have kept isolated PoPs in for Sunday night
into Monday.

MARINE: (Now through Tuesday Night): At 2pm, Buoy 42020 was
reporting SSE winds of 10 to 15 knots with 5ft seas. Meanwhile,
winds of 15 to 20 knots were noted across the bay. These moderate
southerly winds across the Laguna Madre and lighter winds across the
Gulf waters east of Padre Island will continue through early evening
as the surface pressure gradient continues to weaken. Improving
marine conditions will continue overnight as high pressure sets up
across the west-central Gulf with lighter winds and lower seas on
Tuesday.

Wednesday through Monday: Surface high pressure will move westward
into the western Gulf, so the pressure gradient across the lower
Texas coastal waters will relax, improving marine conditions
across the Gulf. Winds may still be moderate out of the southeast,
but hazardous boating conditions aren`t likely. Seas will also
improve to 2 to 4 feet as we move into the second half of the
week.

&&

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

$$

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HTTP://WEATHER.GOV/RGV

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