Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 261131 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
631 AM CDT Tue Sep 26 2017

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


.AVIATION...Brownsville radar currently shows some lingering
convection across the western portions of deep south Texas and
a few streamer showers moving northwest across the lower Texas
coastal waters. Mostly VFR conditions expected through the next
24 hours, with exception of some brief MVFR ceilings around
sunrise from any streamer showers that may develop over the Gulf
waters and move inland. Isolated to scattered showers and
thunderstorms are expected across deep south Texas later today.
Light southeast winds this morning will become moderate later this
morning into the afternoon with some gusts around 20 knots. Winds
will diminish to around 10 knots or less by late this evening.


.PREV DISCUSSION... /issued 439 AM CDT Tue Sep 26 2017/

SHORT TERM (Now through Wednesday): Deep South Texas will remain
between a large-scale trough/500mb low over the western half of the
U.S. and a 500mb ridge over the western Gulf of Mexico through the
period. An upper-level disturbance moving northeast in the southwest
flow aloft is generating a large area of convection across the far
western portions of the CWA early this morning. Brownsville radar
currently shows the heaviest activity across Zapata county with a
few streamer showers moving northwest across the lower Texas coastal

The combination of shortwave impulses rotating through the region,
deep moisture and the seabreeze, should support a good chance of
showers and thunderstorms today and Wednesday. The best rain chances
will be across Zapata, Starr and Jim Hogg counties due to higher QPF
and close proximity to the 500mb trough. Rain chances expected to
linger across the western portions tonight with a few streamer
showers possible near the coast. Abundant cloud cover and increase
rain chances should hold high temperatures down into the low to mid
90s for today and Wednesday. Low temperatures tonight will generally
be in the 70s.

LONG TERM (Wednesday Night through Monday): Isolated to scattered
showers and thunderstorms will continue to be the rule during the
long term portion of the forecast, as deep tropical moisture
(precipitable water values around 2 inches) within Deep South
Texas and the Rio Grande Valley interacts with a pair of 500 mb
low pressure systems that will separately drop into the western
United States. Simultaneously at the surface, a weak cold front
will ease into the Lone Star State, stall, and dissipate north of
the BRO CWFA, helping to generate convection in conjunction with
the 500 mb lows. Near to slightly above normal daytime highs and
overnight lows are forecast through the period courtesy of the
rain chances and increased cloud coverage.

MARINE (Now through Wednesday): Surface high pressure across the
southeastern United States will support light to moderate onshore
winds and low to moderate seas through the period. Isolated to
scattered showers and thunderstorms will prevail at times through

Wednesday Night through Monday: Generally moderate winds and seas
are expected along the Lower Texas Coast Wednesday night through
Sunday night with high pressure over the northern Gulf of Mexico
interacting with low pressure over the Bay of Campeche. Small
Craft Exercise Caution or Small Craft Advisory winds and/or seas
are possible on Monday as the pressure gradient tightens slightly
over the basin.




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