Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 161123 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
623 AM CDT Mon Oct 16 2017

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

&&

.AVIATION...Low to mid level cloud decks and breezy north winds
prevail across deep south Texas this morning. Mainly VFR conditions
expected for all three terminals through the next 24 hours.
Northwest to north winds around 15 knots with wind gusts of 20 to
25 knots will be possible through this afternoon. North winds
diminish by late afternoon into this evening as surface high
pressure settles across the region. Clear skies and light north
winds will persist overnight.

&&

.PREV DISCUSSION... /issued 423 AM CDT Mon Oct 16 2017/

SHORT TERM (Today through Tuesday): Fall-like weather with cool
mornings and comfortable afternoons will prevail through Tuesday in
the wake of last night`s cold front. Elongated surface high pressure
across the area and dry northwest flow aloft will result in dry and
pleasant conditions for deep south Texas through the period. Cooler
and drier air will continue to advect into the area today. Gusty
northerly winds this morning will weaken through the day as skies
clear and surface high pressure builds across the area. High
temperatures today will range from the mid 70s along the coast to
the mid 80s inland and west, which is 5 to 8 degrees below normal
area-wide. Low temperatures tonight will be in the 50s, except for
low to mid 60s at the beaches, under mostly clear skies. High
temperatures Tuesday will be in the low to mid 80s, which is closer
to normal.

LONG TERM (Tuesday Night through Sunday): Dry and stable 500 mb
ridging will remain in place over the U.S./Mexico border region
Tues Night into Wed. The ridging will then start to break down as
a trough axis digs over the top of the ridge and will strengthen
over the southern Plains states Thurs and Fri. Another large 500
mb trough will then dig into the central states from the West
Coast Sat and Sun. The GFS tries to close off the southern end of
this trough axis over central TX on Sun which would keep this
feature somewhat stationary next week. The ECMWF also tries to
close off the southern end of this trough axis but does it much
further east over the central Gulf Coast region next week. Both
the GFS and ECMWF hint at the passage of a weak cold front late
next Sun/early Mon. The surface temps and dewpoints will be
increasing steadily throughout the upcoming longer range period as
the low level flow shifts around to a more east to southeasterly
direction through Day 7.

Deeper layer moisture from the SW Gulf of Mex is expected to
increase over the RGV starting Thurs with the better moisture
levels persisting into the weekend. This increase of moisture in
combination with the approaching 500 mb troughs will allow for
some increase in the conv chcs late in the period.

The GFS and ECMWF 500 mb fields are in reasonable agreement in the
pattern over TX through next Sat. However the models then start to
diverge in the development of the closed low near the Gulf Coast
on Sun. Accordingly the GFS and ECMWF temps and pops are in good
agreement through next weekend but then start diverging next week.

Overall forecast confidence remains above average at this time.
However will have to see if future runs of the ECMWF and GFS show
better consistency for next week. Otherwise will go with a 50/50
model blend through the extended period.

MARINE: (Now through Tuesday): Moderate to strong northerly winds
and elevated seas will prevail along the lower Texas coast today and
tonight. A Small Craft Advisory remains in effect until 1 pm on the
Laguna Madre due to strong winds. A Small Craft Advisory has been
extended and is now in effect for the Lower Texas Gulf waters
through 7 pm this evening. Winds will gradually diminish and seas
subside tonight as surface high pressure settles across the region.
Small Craft Exercise Caution conditions likely on the Gulf waters
Tuesday due to elevated seas.

Tuesday Night through Friday Night: Surface ridging over the
southeastern states will maintain a more onshore flow through Fri
Night. This surface ridging will also maintain a sustained east to
west fetch over the Gulf of Mex which will keep the Gulf swell
activity relatively elevated later this week. However SCA
conditions are not expected for the Gulf waters until possibly
late Fri.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory for winds until 1 PM CDT this afternoon for
     GMZ130-132-135.

     Small Craft Advisory until 7 PM CDT this evening for GMZ150-155-
     170-175.

&&

$$

This product is also available on the web at:
HTTP://WEATHER.GOV/RGV

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