Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 210527 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1227 AM CDT Fri Apr 21 2017

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

.AVIATION...Satellite images and surface observations indicate
mostly clear skies across the CWA late tonight. Ceilings were near
2500ft at KBKS. Expect MVFR conditions to develop early Fri
morning as low level moisture allows clouds to develop. VFR
conditions will prevail after 15Z Friday as low clouds lift and
burn off as mixing increases with diurnal heating. 500mb ridge
across northern Mexico and southwest Texas will continue to
provide subsidence across the CWA Friday.

.PREV DISCUSSION... /issued 651 PM CDT Thu Apr 20 2017/
DISCUSSION...Updated for latest aviation discussion below.

AVIATION...VFR conditions expected through late this evening.
Lower ceilings will develop overnight, with MVFR ceilings likely
through mid morning when low level winds will increase. VFR
conditions will then prevail through Friday afternoon as high
pressure remains in control.

PREV DISCUSSION... /issued 252 PM CDT Thu Apr 20 2017/

SHORT TERM (Tonight through Friday Night): No big changes
expected in the short term. An H5 ridge resides across North
Central Mexico, with a lobe extending over much of Texas. High
pressure lies over the Gulf. Weak, transient low pressure over the
Southern High Plains is contributing slightly to the synoptic
scale pressure field. High pressure will displace Plains lower
pressure Friday night as a front pushes into Texas.

Scattered to broken low clouds will develop tonight, with low
temperatures in the upper 60s to lower 70s. Conditions on Friday
should be a lot like they have been today. Light southeast winds
will become moderate with daytime heating/mixing. Fair weather lines
of CU will form over the CWA, with a weak late morning to early
afternoon sea breeze. Except for isolated sea breeze showers, the
forecast remains dry. High temperatures Friday may be a a degree or
two higher than today, ranging from the mid 80s near the coast to
the mid 90s inland. Another round of low clouds will develop Friday
night, with light winds and low temperatures nudging into the lower

LONG TERM (Saturday through Thursday): The main story for
Saturday will be the approach and passage of a late season cold
front. The main storm system associated with the fropa will be
well to the north of Deep South Texas, passing across Oklahoma
into Arkansas. Given that all the better mid level forcing will be
to the north, and that the mid levels are still dry and stable,
have kept consistent with only slight to chance POPs for showers
and storms. However, the front will act to focus surface-based
forcing of storms in the early afternoon across the Northern
Ranchlands, with chances across the lower RGV in the late
afternoon and evening as the front moves through. Models hint at a
increase in moisture behind the fropa and elevated convection
will be possible mainly across the Western Ranchlands and Upper
Valley. Precip chances will linger across the the RGV through the
early morning hours on Sunday, although most of the activity will
be over by daybreak. Meanwhile, temps on Saturday will still be
will in to the mid 80s to mid 90s across the area ahead of any
precip activity.

Dry weather and cooler temps will begin Sunday with morning lows
in the upper 50s to mid 60s. However, it will be Sunday`s high in
the upper 70s to low to mid 80s that will be noticeably cooler.
High pressure aloft and at the surface will take control to start
the new week with dry conditions expected through mid week.
Monday morning lows could actually be a bit chilly with expected
readings in the low to upper 50s for much of Deep South Texas,
with lows in the 60s near the coast. However, these temperatures
won`t last and readings will again climb quickly through early
next week, given dry air, warm 850mb temps and the ridge in place.


Through Friday night: Surface high pressure over the Gulf will
control marine conditions in the short term. Light to moderate
southeast to south winds and low to moderate seas will prevail.

Saturday through Monday: Seas and winds will lower just ahead of
a cold frontal passage on Saturday. However, marine conditions
will turn hazardous as northerly winds increase behind the front
as the surface pressure gradient increases with a large high
pressure system move south through Texas. Winds and seas will
increase to at least SCA levels for the Gulf waters beginning late
Saturday night or very early Sunday morning and continue through
at least Sunday afternoon. Winds across the Laguna Madre may also
reach SCA conditions early on Sunday as well. The pressure
gradient will weaken late Sunday and much improved marine
conditions are expected for Monday.



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