Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 202307

Area Forecast Discussion
National Weather Service Brownsville TX
607 PM CDT Thu Jul 20 2017

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


.AVIATION...VFR conditions expected to prevail at area terminals
through the forecast period. The very isolated convection that
developed this afternoon along the seabreeze has dissipated.
Current gusty winds will diminish through the evening hours,
becoming light overnight, with the normal diurnal uptick by mid-
morning tomorrow. A few more clouds are possible tonight into
tomorrow morning as an inversion develops, but do not expect MVFR
ceilings to develop.


.PREV DISCUSSION... /issued 249 PM CDT Thu Jul 20 2017/

SHORT TERM (Tonight through Friday Night): A sea breeze will
move slowly inland this afternoon in above average low level
moisture. Convective development will be weak. Mostly clear skies
will take over tonight with high pressure over the Gulf supporting
light southeast winds, and with low temperatures in the mid 70s
to near 80 degrees. Mid-level ridging centered over the Southern
High Plains with extend south over the area, limiting significant
weather in the short term. A few low clouds Friday morning under a
weak inversion will mix out, yielding a mix of clouds and sun
Friday, and still enough moisture under light to moderate
southeast winds to yield a weak sea breeze. High temperatures
Friday may inch a degree or two higher under the persistent mid-
level ridging, ranging from the lower to mid 90s near the coast to
just above the century mark inland west. Heat index values will
range from 103 to 108 degrees mid Friday afternoon. Friday night
will once again be mostly clear with light southeast winds and low
temperatures in the mid 70s to near 80.

LONG TERM (Saturday through Thursday): Long term period begins
the the inverted trough/cutoff low continuing to trek westward
along the Gulf coast. The region will still be on the weaker west
side of the trough, so the subsidence will continue to bring hot
and dry conditions through the weekend. Highs both days will be
near or above 100 degrees, with heat index values approaching 110
each afternoon. By Monday, part of the energy from the cutoff low
will get absorbed northward into a larger passing trough across
the Great Lakes, but the remainder of the energy will continue
westward with the inverted trough. This will be passing by
Monday, beginning to bring more moisture into the region. Tuesday
will see an increase in shower activity as the seabreeze will be
tapping the instability from the passing trough. This instability
will continue into Wednesday. Models are differing after this
point, some keep the trough in the vicinity, while others stretch
the strong ridge back over Texas. Have kept low chances for pops
for the time being, and will wait for further model improvements.

Now through Friday night: Surface high pressure over the Gulf will
support light to moderate southeast to south winds and low to
moderate seas.

Saturday through Monday: Pressure gradient tightens through the
weekend as a front stalls across Oklahoma and North Texas. This
will push winds up to 15 to 20 knots through the period, which
will induce higher waves up to 4 to 6 feet.




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