Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 170920
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
420 AM CDT Tue Oct 17 2017

.SHORT TERM (Today through Wednesday): Fall-like weather will
continue for the next 36 hours as dry northwest flow aloft and
surface high pressure prevails across the region. Light northerly
flow at the surface and very dry air above 850mb will allow
temperatures to rebound into the low to mid 80s this afternoon.
Surface high pressure migrates to the mid-Atlantic coast tonight
allowing light onshore flow to return. Temperatures and dewpoints
gradually recover tonight into Wednesday with the steady onshore
flow. Low temperatures tonight will be in the 50s, except for the
low to mid 60s at the beaches. High temperatures Wednesday will
range from the low to mid 80s near the coast to the upper 80s to
around 90 degrees across the west. Measured water levels continue
to slowly trend down since high tide at 2:26 am this morning,
though are still running more than a foot above predicted. The
Coastal Flood Statement in effect until 5 am will be allowed to
expire.

.LONG TERM (Wednesday Night through Monday): A 500 mb trough will
be digging over the southwestern and south central states around
mid week. This trough will move slowly eastward through Thurs and
Thurs Night with moisture values slowly increasing over much of TX
through this period. Accordingly the conv chcs will gradually
increase on Thurs likely peaking on Fri as the 500 mb trough axis
clears the RGV. Another larger 500 mb trough axis will then dig
across the western states and the Rockies later this week pushing
into TX late Sat/early Sun. As this trough clears through the
region Sun it will usher another cold front through the RGV. Once
again some better moisture values pool over the RGV just ahead of
2nd 500 mb trough passage. So expect the conv potential to spike
once again on Sunday. 500 mb ridging will then prevail next Mon
and Tues resulting in fairly warm temps and low pops.

Although the GFS and ECMWF have come into better agreement in the
handling of the 500 mb pattern through Day 7, bigger disagreements
are showing up between the two longer range model sets concerning
pops. The GFS is going with a drier forecast mainly after Fri with
the ECMWF holding onto higher pops on through Sun. The ECMWF has
shown better run to run consistency for the conv potential with
the GFS showing more volitility for pops in recent runs. So will
lean closer to the wetter ECMWF numbers.

The ECMWF and GFS temps are in good agreement through Day 7 and
will go close to a blend of these two models for maxes and mins.

Despite the increasing disagreement in the pops between the GFS
and the ECMWF, overall confidence in the longer range forecast
period wording remains above average.

&&

.MARINE (Now through Wednesday): Marine conditions will continue to
improve along the lower Texas coast through the period. Small Craft
Exercise Caution conditions will linger on the Gulf waters 20 to 60
NM east of Padre Island through early this afternoon. More favorable
marine conditions develop on the Gulf waters by tonight with light
to occasional moderate northeast to east winds and seas of 3 to 4
ft.

Wednesday Night through Saturday Night: Surface ridging settling
over the southeastern and eastern states will maintain a moderate
east to southeast low level flow over the lower TX bay and Gulf
waters through Sat night. The Gulf swells may briefly push up to
SCEC or marginal SCA conditions late Thurs into Fri as the surface
winds offshore edge up a bit. However overall the Bay and Gulf
conditions should remain below SCA criteria for most of the longer
range period.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  80  62  84  68 /   0   0   0  10
BROWNSVILLE          84  60  86  67 /   0   0   0   0
HARLINGEN            83  57  87  65 /   0   0   0   0
MCALLEN              85  57  88  66 /   0   0   0   0
RIO GRANDE CITY      85  55  90  62 /   0   0   0   0
SOUTH PADRE ISLAND   80  66  83  72 /   0   0   0  10

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory until 4 AM CDT early this morning for
     GMZ150-155-170-175.

&&

$$

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

Short Term...63
Long Term...60
Graphicast/Upper Air...62



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