Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 202319 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
619 PM CDT Fri Apr 20 2018

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

.AVIATION...Surface winds are beginning to diminish with a few low
clouds in place right now. Moderate winds are expected overnight
as cloud cover increases and slips into MVFR territory. A return
to VFR will occur tomorrow as breezy winds prevail and cloud decks

.PREV DISCUSSION... /issued 315 PM CDT Fri Apr 20 2018/

SHORT TERM (Tonight through Saturday Night): Upper-level low pressure over
the Four Corners region will continue to move eastward this evening
with broad diffluence in the mid layers through Saturday. At the
surface, winds are gradually shifting from the east to the southeast
today as higher pressure builds over the northern Gulf. At the
surface, a weak northward-moving boundary was evident on radar and
satellite imagery earlier. This was likely the cold front that moved
through yesterday, returning northward as a warm front. No real
impacts are seen with this front other than increasing cloudiness
across Deep South Texas. Shower activity has been absent as moisture
remains limited to near the surface. Dry air above 850mb, especially
over the RGV, will limit convection through the night and into
Saturday. Models are indicating very low PoPs, which seems
reasonable, but have kept mentionable chances on Saturday with the
upper low moving across North Texas and moderate southeast winds
bringing a bit more moisture in. Temperatures today have been
cooperating in the low to mid 80s range, which is just about normal
for this time of year. Highs tomorrow may be a few degrees warmer
with more of a southerly wind component compared to today.

LONG TERM (Sunday through Friday): 500mb low/trough across
southeast Oklahoma Sunday will move eastward across
Mississippi/Alabama Monday. At the surface...a frontal system
across the Arklatex Sunday will bring a weak cold front into the
Rio Grande valley. Moisture appears too limited to mention rain
chances except across extreme southeast portions of the CWA
Sunday. Surface high pressure will build into south Texas in the
wake of the front Sunday into Monday. Low to mid level moisture is
expected to increase across northeast Mexico Sun night into Monday
but convection should remain well to the southwest of the area. A
surge of drier air is progged to move into deep south TX Tuesday
as 500mb ridge across northern Mexico and west TX provides
subsidence across south TX. The global models continue to bring a
500mb shortwave trough across the northern plains Tuesday into the
midwest and Ohio River valley Wednesday. A weak cold front is
expected to move into south TX Wed afternoon before stalling.
Moisture is progged to increase across the CWA Wed night into
Thursday but will not mention rain chances Thursday. A stronger
500mb shortwave trough is expected to develop and move across the
east-central U.S. Thurs night into Friday. The 12Z GFS brings a
cold front through the Rio Grande valley Friday providing a slight
chance of showers and thunderstorms across the area Thurs night
into Friday. There are some differences between the ECMWF and GFS
Wednesday and Thursday but they appear to be somewhat in
agreement on Friday so will adjust temperature model blends
slightly cooler towards the end of the forecast period as a

MARINE (Now through Saturday): Higher pressure continues to build
over the northern Gulf, so winds are gradually shifting from the
east to southeast. Winds are a bit stronger on the bay waters, so
small craft should exercise caution this afternoon. Do not
anticipate any Small Craft Advisories, but winds may range from 15
to 20 knots on Saturday with moderate seas.

Sunday through Wednesday...Light south winds will shift to the
north and increase from the northeast Sunday as a weak cold front
moves through the coastal waters. Light northeast winds will
prevail across the western Gulf of Mexico Monday with surface
high pressure across south Texas and the western Gulf. The
pressure gradient will remain weak across the lower TX coast
Tuesday with surface high pressure across the western Gulf. Winds
will veer to the east but remain light Wednesday as a weak cold
front moves into south TX.



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