Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 220532 AAB

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1232 AM CDT Sat Apr 22 2017

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

.AVIATION...Satellite images and surface observations indicate a
few low clouds across the CWA late tonight. Expect MVFR conditions
to develop the rest of tonight into early Sat morning as low
clouds develop ahead of a cold front moving through central Texas.
VFR conditions will prevail after 15Z even as low level moisture
continues to increase along and ahead of the front. The front will
move through the CWA Sat afternoon and some isolated convection
will develop along the boundary.

.PREV DISCUSSION... /issued 655 PM CDT Fri Apr 21 2017/
DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Mainly VFR should prevail over the next 24 hours.
Breezy SE winds of this afternoon have already begun to settle
down. Overnight, expect that a low cloud deck will form around
midnight at 020-025, but confidence not particularly high that a
ceiling will prevail. SREF probabilities of MVFR CIG`s only in
the 20-30% range, and RAP BUFKIT soundings showing the thickness
of the cloud layer to be rather shallow. Patchy fog was inherited
in the public forecast grids, but currently thinking that winds
will stay up enough to prevent temps from cooling to the dewpoint.
SE breezes return mid-morning on Saturday, but should weaken by
mid-afternoon and back somewhat as the pressure gradient
decreases ahead of an approaching cold front.

At this time, model solutions are consistent in keeping the cold
front north of the RGV airports through 23/00Z. Isolated
convection may develop along and behind the front tomorrow
evening, with MFE perhaps being favored.

PREV DISCUSSION... /issued 245 PM CDT Fri Apr 21 2017/

SHORT TERM (Tonight through Saturday Night): The most
significant event in the short term portion of the forecast will
be the passage of a weak cold front through Deep South Texas and
the Rio Grande Valley early Saturday evening through early
Saturday night. The Storm Prediction Center has placed the entire
BRO CWFA in a general risk of thunderstorms from Saturday morning
through Sunday morning, and isolated showers and thunderstorms
will be included in the upcoming local forecast from Saturday
afternoon through Saturday night. Temperatures will prevail at
above normal levels in advance of the front, but cooled to below
normal levels Saturday night in the wake of the front.

LONG TERM (Sunday through Friday): Have not made any significant
changes to the forecast this afternoon. Current thinking is that
some light lingering rain will be possible across the Lower RGV
for a few hours Sunday morning, with the cold front now south of
the region. Any precip should exit the Deep South Texas by mid to
late morning with cloud cover continuing to hold on over the RGV
through mid day. After that, high pressure will build south into
the area will much drier Plains air. This will erode away cloud
cover rather quickly, with mostly sunny skies by the afternoon.
The real story will be how much cooler it will Sunday, with
readings topping out nearly 10 degrees lower than the day before.

By Monday morning, under mostly clear skies and near calm to light
high pressure winds, temperatures will have fallen into the 50s
for much of the areas, with the exception of locations right along
the coast. In fact, these readings could be around 10 degrees
below normal lows for late April. With ridging aloft and surface
high pressure in place to start the new work week, the dry air
will warm quickly and highs Monday will be right back to near
normal. The warming trend will continue through the week, with
both highs and lows warming a few degrees each day. Triple digit
readings across the mid to upper RGV and Western Ranchlands are
likely Wednesday though Friday, with mid to lower 90s from the
mid valley towards the coast. Meanwhile, the forecast is expected
to remain rain free.


Tonight through Saturday Night: Buoy 42020 reported south winds
around 12 knots with seas slightly under 3.5 feet with a period of
8 seconds at 13 CDT/18 UTC. Generally moderate winds and seas
will prevail along the Lower Texas Coast in advance of a cold
front, which will sweep from north to south through the waters
from early Saturday evening through early Saturday night.
Increasing winds and building seas are likely in the wake of the
front, and Small Craft Advisories may be needed for all or
portions of the Lower Texas coastal waters Saturday night after

Sunday through Tuesday: Hazardous winds and seas will continue
across the Gulf waters on Sunday, with any SCAs from the night
before continuing into the morning or afternoon hours due to the
tight surface pressure gradient behind the front. The winds and
seas will improve later on Sunday as high pressure quickly
settles across Deep South Texas and the Western Gulf with the
gradient relaxing. Light winds and lows seas will be noted on
Monday and for the better part of Tuesday. However, by later on
Tuesday, the pressure gradient will quickly tighten as the surface
high pressure shift into the Central Gulf of Mexico and interacts
with another developing low pressure system across the Panhandles
of Texas and Oklahoma. Winds and seas may approach SCA conditions
by Tuesday evening.



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