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FXUS64 KBRO 170956
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
356 AM CST Sat Nov 17 2018

.SHORT TERM (Today through Sunday): An elongated 500 mb trough axis
will dig southwards into the central Plains States today and Sun.
The approach of this trough axis will push a cold front down into
southern TX late Sun. Deeper layer moisture will pool ahead of this
elevated trough and cold front especially near the lower TX
coastline and extending out offshore in the western Gulf of Mex.
Since the 500 mb trough axis will likely be sheared out from west to
east across the central PLains, the cold front will have some
difficulty clearing the RGV. Accordingly, the MSL fields from the
short term guidance from the various model sets shows a strong
indication that coastal surface troffing will form up near the
lower TX coastline which will in turn help enhance the surface
convergence and the better pops/QPF values across the marine areas
starting tonight and continuing into Sun. Model blended pops
indicate chc pops starting tonight. The pops then increase and
become more widespread into Sun as the cold front pushes closer to
the RGV.

AS the moisture levels increase and the low level WAA continues
through tonight and Sun, the CAPE values will increase somewhat.
This will interact with the increasing low level convergence
associated with the approaching cold front to increase the risk of
some thunderstorms on Sun. So will maintain a mention of isold t-
storms for tomorrow.

Low level CAA will be somewhat limited in behind the cold front on
Sun. However the increasing cld cover and pcpn chcs will likely
lower the high temps some tomorrow. The NAM is the warmest for
highs tomorrow keeping the maxes in the lower 80s. The NAM MET
numbers are also the outlier in comparison to the GFS and the ECMWF
numbers. So will lean closer to a blend of these two model sets
since the NAM is the odd model out.

.LONG TERM (Sunday Night through Friday): An unsettled weather
pattern is expected through midweek. A weak cold front and surface
low pressure will move across deep south Texas Sunday night into
Monday. However, models continue to differ on the timing and the
placement of the front and surface low pressure. The cold front is
expected to become stationary south of the Rio Grande river on
Monday as a coastal trough develops off the lower Texas coast.
Overrunning should provide widespread rain across the area on Monday
and Monday night with the best rain chances along the coast. Higher
rain chances continue near the coast Tuesday into early Wednesday as
the coastal trough remains in place. A 500 mb shortwave trough
moves over Texas on Wednesday with mid level ridging build over the
region. The coastal trough is expected to move northeast late
Wednesday into Thanksgiving day. Lingering moisture may support
isolated showers along the coast Thanksgiving day.

The GFS remains the warmest of the models for temperatures, the NAM
is much colder, while the ECMWF is in the middle. Will lean towards
a combination of the latest Superblend and previous forecast.
Thanksgiving day looks nice with mild temperatures and clearing
skies.

&&

.MARINE (Today through Sunday): A moderate SE surface flow will
prevail across the lower TX Bay and Gulf waters this weekend as
surface ridging prevails over the Gulf of Mex. Expect the swell
activity to increase steadily tonight into Sun possibly pushing into
SCEC/borderline SCA criteria on Sun. For know will not post up any
SCAs as overall confidence in the Gulf conditions reaching SCA
levels for an extended period of time is low.

Sunday night through Wednesday night...A weak cold front arrives
Sunday night into Monday morning. Elevated seas and moderate winds
are expected to develop in the wake of the front Sunday night and
continue through Tuesday night. A Small Craft Advisory will be
possible across the lower Texas Gulf Waters Sunday and Monday.
Marine conditions are expected to improve on Wednesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL 78 67 77 61 / 20 50 70 60
BROWNSVILLE 80 67 78 61 / 20 50 60 60
HARLINGEN 79 65 78 59 / 20 40 60 60
MCALLEN 79 66 79 60 / 20 40 50 60
RIO GRANDE CITY 80 63 75 56 / 10 30 50 50
SOUTH PADRE ISLAND 78 70 74 63 / 20 60 70 60

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

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

Short Term...60
Long Term...63
Graphicast/Upper Air...67
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