Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 280532 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1232 AM CDT Wed Jun 28 2017

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

.AVIATION...The previous suite of TAFs have been reworked to
reflect the waning convection offshore and the current run of
the HRRR model, which suggests a lack of showers/thunderstorms
Wednesday morning but an increase in the afternoon. Veering
surface winds are also anticipated as weak low pressure moves
up the Texas coastline.

.PREV DISCUSSION... /issued 653 PM CDT Tue Jun 27 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Daytime convection has waned with VFR to prevail
at the 3 air terminals overnight. Low pressure trough remains east
of the Padre Island and an upper level trough persist over South
Texas with abundant moisture in place keeping the chance of
additional showers and thunderstorms in the forecast. Expected
activity to refire over the gulf waters overnight and drift
towards the coast and the eastern counties around sunrise
Wednesday increasikng in coverage east to west during the late
morning and afternoon hours. Mostly VFR with some brief MVFR cigs
can be expected with the scattered convection. Winds will be light
and variable tonight with light east to southeast.

PREV DISCUSSION... /issued 320 PM CDT Tue Jun 27 2017/

SHORT TERM (Tonight through Wednesday Night): A weak mid-level
trough in the 500mb flow is located over South Texas along with
surface troughing along the lower Texas coast. With abundant
moisture from the surface up to 500mb, shower and thunderstorm
chances will continue through this evening. Locally heavy rainfall
will be possible with precipitable water values at 2.25",
measured from the 12Z BRO sounding. Tonight, a fairly weak
vorticity maximum is being noted in the 12Z model guidance, so
another round of showers or storms is possible late tonight across
Deep South Texas. The HRRR has consistently been picking up on
isolated convection as well, so have left slight chance PoPs in
for 00-06Z tonight.

Wednesday, mid-level trough axis will likely be oriented along the
coastal areas, so the main rain chances will be over the eastern
half of Deep South Texas and over the marine areas. Temperatures
should be able to warm up a few more degrees than today due to
slightly lower rain chances and clouds expected. Surface high
pressure will build over the Southeast US, so winds will return to
the southeast going into Thursday afternoon.

LONG TERM (Thursday through Tuesday): Weak H5 trough between
Ridges to the east and west will begin to break down Thursday into
Friday, allowing the eastern ridge to build back into south Texas.
There will still be enough instability and moisture in the region
Thursday to provide a slight chance for showers on Thursday, but
low level jet will increase shear on any of these showers. Drier
air moves in aloft by Friday morning, bringing nearly all shower
activity to an end at least through the weekend, and likely into
early next week. This will allow temperatures to slowly increase
each afternoon through the 90s and above the 100 degree mark out

MARINE: Now through Wednesday night: Weak surface troughing
along the coast will maintain light and mainly variable winds over
the lower Texas coastal waters tonight into Wednesday, with
exception to near any thunderstorms that develop. Surface high
pressure will build and shift to the Southeast US and return
southeast flow late in the period on Thursday. As low pressure
deepens in the Central Plains, winds will increase and seas will
eventually build to 3 to 4 feet.

Thursday through Sunday: Increasing gradient through the weekend
will cause gusty southeast winds for the marine areas. Southeast
winds will reach near 20 knots each day, approaching advisory
criteria. This will also kick seas up to 5 to 6 feet offshore and
cause choppy laguna waters. Some improvement is noted for Sunday,
with winds weakening to 10 to 15 knots. Seas may take a while to
decrease Sunday morning once the winds decrease.&&



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