Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 241146 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
646 AM CDT Sun Sep 24 2017

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

&&

.AVIATION...KBRO radar has shown some patchy marine showers
trying to edge in along the coastline from the Gulf of Mex
throughout the overnight hours. All of these patches of conv have
been dissipating as they reach the coastline and encounter more
stable air.  Accordingly will include a mention of vcsh for the
BRO and HRL areas for the first few hours of the current TAF set.
Expect daytime heating and the local sea breeze effects to fire
off some isold/sct conv during the afternoon and early evening
hours today. This activity will likely be sparse enough to limit
the aviation impacts to the local airports. So will go with
overall VFR conditions of the RGV aiports with some brief
reductions to MVFR levels due to lowered ceilings from any conv
that passes near the RGV airports. However will only mention vcts
during the afternoon hours.

&&

.PREV DISCUSSION... /issued 421 AM CDT Sun Sep 24 2017/

SHORT TERM (Now through Monday): KBRO radar shows some patchy
marine showers trying to edge in along the coastline from the Gulf
of Mex. The 00z BRO sounding shows that the atms CAPES and PWAT
values over the RGV have not changed much over the previous 24
hours. 500 mb troffing continues to slowly strengthen over the RGV
as a deep closed low digs east from the western states and another
open trough over the Gulf coast drifts west towards the TX coast.
This increasing 500 mb troffing will combine with the daytime
heating to help generate some afternoon and early evening conv over
the region. The GFS and ECMWF pops through the short term range
generally in the 20 % range through tomorrow while the NAM comes in
the wettest with conv chcs around 30 %. So will opt for a model
blend of the short term pops. For temps will edge back the highs a
bit today and Monday as the 500 mb troffing increases over the
region.

LONG TERM (Monday Night through Saturday): The forecast period
begins with a large scale mid-level trough over the western CONUS
and a mid-level ridge over the western Gulf of Mexico. The trough
weakens by mid-week with a cut-off 500mb low becoming centered near
the Four Corner region on Thursday. Mid-level ridging remains
anchored along the Texas coast through the period. Precipitable
water values near or above two inches will support scattered showers
and thunderstorms Tuesday through Thursday. The best rain chances
will remain across the western portions of deep south Texas due to
the close proximity to the mid-level low. The GFS remains the most
robust on rain chances for Tuesday through Thursday.

A cold front is expected to move across northern Texas on Tuesday
and will gradually move south through the week. Deep tropical
moisture is expected to pool ahead and along the frontal boundary.
The GFS/ECMWF continues to suggests the front will move into deep
south Texas Thursday night into Friday. Rain chances diminish Friday
night into Saturday as drier air slowly filters into the region in
the wake of the front. Temperatures will to remain above normal
through Thursday night due to abundant cloud cover and increase rain
chances. Near to slightly below normal temperatures are expected
Friday night through the weekend as surface high pressure builds
into the region.

MARINE (Now through Monday): Broad surface ridging sprawled over
the eastern states will maintain low to moderate winds and seas
across the lower TX coastline. Expect SE winds across the region
with Gulf seas ranging generally in the 2 to 3 foot range. A light
to moderate chop is expected on the Laguna Madre through tomorrow.
No SCA conditions expected through Monday.

Monday Night through Thursday Night...Favorable marine conditions
with light to moderate onshore flow and low to moderate seas will
prevail through late week. Isolated to scattered showers and
thunderstorms are expected at times, especially late night into the
early morning. A cold front is forecast to move through deep south
Texas and the adjacent coastal waters Thursday night into Friday.
Small craft exercise caution conditions likely in the wake of the
front due to higher winds and elevated seas.

&&

.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...62


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