Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 152352 AAA

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
552 PM CST Fri Feb 15 2019

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

.AVIATION...The main concern tonight will be fog. Model guidance
suggests that fog will form at the aerodromes during the overnight
hours, but the intensity will likely be dictated by the strength
of the winds, and visibilities could easily be better or worse
than indicated in the current suite of TAFs. Full VFR is likely
tomorrow after sunrise.

.PREV DISCUSSION... /issued 311 PM CST Fri Feb 15 2019/

SHORT TERM (Now through Saturday night): Overall synoptic
pattern includes zonal flow aloft with a very dry atmosphere from
the near- surface up to 300mb, with only enough moisture for some
upper-level cirrus clouds this afternoon. In the low levels, winds
have picked up to 25 mph at times out of the S to SSW. This,
combined with mostly sunny skies, has led to well-above-normal
temperatures this afternoon across all of the CWA. A few locations
may hit 93 to 95F before peak heating ends in the next hour or
so. Mild conditions are expected this evening with above-normal
lows overnight. The main concern in the short term will be fog
potential. We are already seeing some marine fog develop, as
expected, this afternoon. And models indicate some radiational fog
will develop overnight. Patches of dense fog will be possible if
winds can lighten just enough.

Saturday will be another warm day, but should be a couple degrees
cooler than today. Models bring a weakening front in the northern
areas of the CWA, with only a mild backing of winds to the east and
possibly northeast up north. Still, the atmosphere is very warm in
the low levels, so above-normal temperatures are anticipated, with
highs in the upper 80s to low 90s out west. Continued to go well
above all model guidance, which has worked out so far today. If
light easterly flow develops along the coast, a sea breeze will be
possible, dropping temperatures a bit more Saturday afternoon.
Regardless, moisture will be very limited, with models showing RH
values of 30% right off the surface and into the mid levels.

LONG TERM (Sunday through Friday): A period of unsettled weather
is anticipated for the long term as a cold front moves through on
Sunday with an upper Western U.S. trough to set up and remain
quasi- stationary over the Desert SW until next weekend.

Model are in overall good consistency with the west coast trough but
differ in timing in the west to east movement of shortwaves and
disturbances within the developing deep southwest flow. Temperatures
begin to fall later Sunday with a more substantial drop to below
normal highs and lows Monday-Friday and may even linger into next
weekend with the trough axis remaining west of Texas and a coastal
trough/low lingering over the Western Gulf keeping our region in a
generally cool north-northeast surface flow. As for precipitation
chances probabilities trend upward post front but vary with the
passage of the mid/upper level disturbances and proximity of the
coastal troughing or weak low pressure area(s) that may form along
the coastal trough/old frontal boundary.

As for guidance pops and temperatures MEX/EC are in pretty good
agreement with both models pointing towards Wednesday and Thursday
as the coolest and wettest days of the week. Expect the forecast to
be advised day to day with lower confidence in timing of the
disturbances within the SW flow.

MARINE:(Now through Saturday night): The main concern with the
coastal waters will be fog potential. We are already seeing marine
fog develop along the nearshore Gulf waters, and is verified on
visible satellite and local webcams. Have issued a Marine Statement
for low visibilities, but conditions will need to be monitored for a
possible advisory if fog expands or thickens this evening and
overnight. Otherwise, moderate southerly winds will keep seas at 3
to 5 feet offshore and around 2 to 4 nearshore ahead of a weak front.

Sunday through Thursday: Moderate cold front moves through the
coastal waters Sunday afternoon and pulls up stationary near the
Lower Texas coast Monday and lingers nearby through much of the
week. A moderate to occasional strong north to northeast flow
provides unsettled marine conditions much of the period. The days
with the most unsettled conditions, which might warrant small craft
advisories, look like Sunday night and Monday then again Wednesday
into Thursday.



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