Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 111740 AAC

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1240 PM CDT Wed Oct 11 2017

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

.AVIATION...Satellite and radar images as well as surface
observations indicate elevated convection across the southeast
portions of the CWA early this afternoon. Ceilings were near
1700ft at KBRO to near 3500ft at KAPY. Visibilities were near 5SM
with rain and mist at KPIL. Expect MVFR conditions to prevail
across most of the Rio Grande valley and northern ranchlands the
rest of the afternoon into the evening as low to mid level
moisture across northeast Mexico and deep south Texas in
combination with a stationary frontal boundary across the
northwest Gulf of Mexico continues to produce showers and
thunderstorms across the coastal sections of the CWA.

.PREV DISCUSSION... /issued 852 AM CDT Wed Oct 11 2017/
DISCUSSION...Satellite and radar images indicate elevated
convection across southeast portions of the CWA with surface-
based convection offshore the lower Texas coast this morning. The
heaviest rainfall is confined offshore with light to moderate
rainfall across the coastal sections of the CWA and lower Rio
Grande valley. Lighter rainfall...mainly stratiform and
elevated...continues to fall across the middle portions of the Rio
Grande valley. Have increased POPS across the eastern portions of
the CWA this morning and may have to increase rain chances this
afternoon. Have also increased QPF this morning...mainly across
the eastern portions of the reflect higher rainfall
amounts and may also need to increase these amounts later this

PREV DISCUSSION... /issued 633 AM CDT Wed Oct 11 2017/
DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Brownsville radar continues to indicate an area of
stratiform rainfall across Cameron county and some stronger
convection south of the Rio Grande River extending into the
Gulf waters. Otherwise, MVFR ceilings and light to moderate
northwest winds prevail across deep south Texas this morning.
Aviation conditions expected to trend closer to MVFR/VFR levels
later this morning into the afternoon with light rain/showers
lingering as surface coastal troffing is expected to form near the
lower TX coastline helping enhance the low level convergence.
MVFR ceilings will likely continue through this evening at BRO/HRL
and may return to MFE after 03z. VFR ceilings may develop late
tonight, mainly after 09z, at BRO/HRL.

PREV DISCUSSION... /issued 352 AM CDT Wed Oct 11 2017/

Cooler and Cloudy Today...

SHORT TERM (Today through Thursday): Brownsville radar currently
indicates some convection over the offshore Gulf waters and a few
showers across the ranchlands. The combination of deep moisture
in place and the formation of a weak coastal trough will continue
to produce isolated to scattered showers for today, mainly along
the coast. Rain chances will linger tonight and Thursday due to
the weak coastal trough and low to mid level moisture.
Temperatures will be below normal today due to abundant cloud
cover and slightly cooler air filtering into the region. High
temperatures today will generally be in the mid to upper 70s. The
cooler temperatures today will be short lived as above normal
temperatures return for Thursday. Low temperatures tonight are
expected to be in the 60s, except around 70 near the coast. High
temperatures on Thursday will be in the mid to upper 80s.

LONG TERM (Thursday Night through Tuesday): At the start of the
long term period the RGV will be between a high pressure system
across the southeast US and a stubborn coastal trough to our south
helping producing an overall easterly flow. This is important in
regards to potential convection right along the sea breeze. That
in mind, kept rain chances going through the weekend, especially
along and east of the I69C/HWY 281 corridor.

Aloft, high pressure will be in control which may help limit
aforementioned convection just slightly. This high should eventually
begin to build west and southwest with time. Warm to even hot
conditions (above climo) can be expected, especially inland. As the
ridge continues to build westward toward the Desert Southwest, our
upper level flow will begin to shift more out of the northwest a mid
level wave and surface frontal boundary progresses eastward across
the central United States on Monday. Globals actually agree pretty
well with timing and passage of this front (Monday PMish), however,
the exact strength and rainfall chances (if any) is still a bit
murky at the moment.

MARINE (Wednesday through Thursday): Moderate to strong north to
northeast winds prevail along the lower Texas coast early this
morning. The previous Small Craft Advisory for the Gulf waters has
now been extended until 10 am due to strong winds and elevated
seas. The pressure gradient will remain relatively strong across
the western Gulf of Mexico today resulting in moderate north to
northeast winds and elevated seas. Marine conditions will begin to
improve tonight as winds and seas diminish due to the weakening
pressure gradient. Light east winds and low to moderate seas
expected along the lower Texas coast on Thursday as high pressure
spreads over the area.

(Thursday night through Tuesday): An easterly fetch is expected
to develop Friday and into Saturday between the trough across the
Bay of Campeche and the surface high pressure across the
Appalachians. That said, the overall thinking is that the high
will be weakening a good bit, which should keep the pressure
gradient from causing much of a problem, at least through the
weekend. This should promote light to moderate winds and seas.
With the presence of the trough to our southeast, think off and
on/isolated to scattered showers may be possible for the adjacent
gulf waters this weekend.

Early next week a cold frontal boundary is poised to move into the
area. Once again, gusty winds and rougher seas will be likely,
however, exact specifics regarding marine impacts are still a bit



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