Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 151135 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
635 AM CDT Sat Jul 15 2017

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


.AVIATION...Periodic LIRF to IFR visbys will continue at KHRL through
the next hour or so as field fog drifts by. Do think that
conditions will improve quickly after sunrise as it did on Friday.
Otherwise, low visbys have yet to materialize elsewhere and have
removed mention from KBRO and KMFE. Still expecting some some
seabreeze convection, however have not mentioned any VCSH given
that it will remain isolated. The next inverted trough will
approach late tonight with more moisture and increased cloud cover


.PREV DISCUSSION... /issued 415 AM CDT Sat Jul 15 2017/

SHORT TERM (Now through Sunday): The short term forecast will
continue to be rather benign for Saturday as subsidence continues
to affect Deep South Texas and the RGV in the wake of the inverted
trough exiting across West Texas. As such, it should be another
mostly to partly sunny day across the area with only small chances
of isolated convection across mainly the coastal counties or
locations east of I-69C/Hwy281 corridor. Any activity will likely be
seabreeze induced at that, and nothing widespread is expected. To
that west, dry air remains firmly in place and showers are unlikely.
it will be another warm day as well, with highs generally running
near or within a degree or so of the norm.

By Saturday night into Sunday, the next round of tropical moisture
will approach as yet another inverted trough moves into the coastal
waters. The chances for scattered showers and thunderstorms will
increase through the day Sunday as the wave moves west, although the
best chances may be across the Northern Ranchlands during the
afternoon. The upper level pattern looks to keep much of the
moisture funneled between the inverted trough and the high pressure
over the Southern Plains, pushing the best moisture to our north.
Models still differ slightly on the amount of available moisture.
The GFS remains drier, keeping PWATS right around normal, about
1.7", and POPs barely mentionable. Meanwhile, both the NAM and ECMWF
show deeper moisture with PWATS approaching 2.0" and markedly higher
POPs. Have trended back ever so slightly with POPs, but have still
left a good 30-40% mention across the region on Sunday. There could
be some possibility of locally heavy rainfall on Sunday, however
this would remain isolated. However, if training of shower/storms
occur, nuisance urban or street flooding will be possible.

At the very least, cloud cover should be more widespread. This will
in turn keep high temperatures lower on Sunday, and have generally
left them at 2 to 4 degrees cooler than today.

LONG TERM (Sunday Night through Friday): Warm and humid
conditions continue across Deep South Texas through the period.
Isolated to scattered scattered showers and thunderstorms will be
possible each day. The best rain chances will be Sunday night and
Monday as a 500mb inverted trough moves overhead. The ECMWF
continues to show robust pops across the area Sunday night and
Monday while the GFS remains drier suggesting that highest
precipitable water values should remain north and west of the Rio
Grande Valley. Mid-level ridging begins building over the western
Gulf from the north Tuesday into Wednesday. The GFS/ECMWF show some
disagreement towards the end of the week regarding the possible
approach of the next inverted trough and moisture surge.
Temperatures will be near to slightly above normal through the
period. High temperatures each day will range from the low to mid
90s near the coast to the upper 90s to triple digits across the
west. Overnight low temperatures will remain in the mid to upper 70s
to around 80 along the beaches.

MARINE (Now through Sunday): At 3 A.M. this morning, Buoy 42020 was
reporting light south winds of less than 10 knots and seas of 1 to 2
feet. Broad surface high pressure over the Gulf will keep the
pressure gradient weak through the weekend. Light southerly winds
will  be noted today through Sunday, although winds will become
variable Saturday night. Seas will generally remain less than 2
feet. However, showers/storm chances will increase Saturday night
and will continue to be scattered across the coastal waters on

Sunday Night through Wednesday Night: Favorable marine conditions
expected through midweek as broad surface high pressure remains in
control across the Gulf. Light to moderate south to southeast
winds and generally low seas will prevail along the lower Texas
coast through the period. Showers and thunderstorms will be
possible at times across the coastal waters Sunday night through
Wednesday night.




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