Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 260549 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1249 AM CDT Fri May 26 2017

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

&&

.AVIATION...Mostly cloudy skies with southeast winds around 15
knots prevail across Deep South Texas early this morning. Winds
will become breezy later this morning into the afternoon as low
pressure across west Texas interacts with Gulf high pressure. MVFR
ceilings expected to persist overnight with brief periods of
scattering out. Full VFR should return by early afternoon as the
cloud layer mixes out. MVFR ceilings will develop late in the
period mainly after 2z Saturday.

&&

.PREV DISCUSSION... /issued 646 PM CDT Thu May 25 2017/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...Tight pressure gradient across Texas and the Gulf of
Mexico will keep breezy SE winds going until an hour or so after
sunset, with winds expected to remain at moderate levels through
the night at all of the terminals. Winds quickly pick back up to
breezy levels by mid-morning, continuing into the afternoon, but
do not expect Airport Weather Warning criterion of 35KT to be
threatened at either BRO or HRL.

Lowered CIG slightly for the overnight hours at all three
terminals. Confident that MVFR ceilings will develop, though there
could be brief periods of scattering out, as suggested by MOS
guidance and RAP forecast soundings. Full VFR should return by
early afternoon as the cloud layer mixes out.

PREV DISCUSSION... /issued 249 PM CDT Thu May 25 2017/

SHORT TERM (Tonight through Friday Night): 500mb ridge across
the central United States this afternoon will begin to move
eastward tonight into Friday as a 500mb subtropical ridge develops
across northeast Mexico and the Rio Grande valley. This will
continue to provide subsidence across the CWA even as an onshore
flow continues to increase across the lower Texas coast tonight
into Friday. Very warm...breezy and humid conditions will prevail
across the Rio Grande valley and northern ranchlands tonight
through Fri night with no rain chances expected through the
period.

LONG TERM (Saturday through Thursday): Hot and dry weather will
prevail Saturday with weak ridging over the southeast United States
and high pressure over the Gulf. High temperatures locally will
range from the lower 90s to above the century mark. Heat index
values will increase to between 105 and 110 degrees Saturday
afternoon. A front will overtake the dry line upstream, provoking
convection over the Big Bend area of Texas. By Sunday, with a mean
trough over the upper Midwest and ridging again building over the
western United States, high pressure will spill southeast from the
upper northwest United States, pushing into central Tex. A similarly
hot day relative to Saturday will prevail Sunday, with upstream
convection edging closer with the slow moving front. Convection will
fire over the RGV Plains Sunday night with a few cells possibly
moving into the northwest sector of the CWA. The front will approach
the CWA on Monday, less emphatically than before, with winds
weakening and with some uncertainty as to whether the front will
have enough push to make it through. At any rate, the atmosphere
will be slightly destabilized resulting in an increase in rain
chances, particularly inland, where convection may fire late Monday
night into Tuesday morning. Southeast flow will regain its footing
on Tuesday and Wednesday, plus a destabilizing mid level low will
approach from the west, with diurnal showers firing over the CWA
while the lingering front is stalled or pushed back north. Only by
Thursday will rain chances settle down to the more benign coastal
sea breeze type, as the upstream low edges northeast. A weakness
above the southwest Gulf may begin to trigger convection offshore
the latter half of next week.

MARINE (Tonight through Friday night): Seas were near 4 feet with
south to southeast winds near 21 knots at buoy020 this afternoon.
Moderate to strong south to southeast winds will prevail across
the coastal waters tonight as low pressure across the southern
plains and high pressure across the eastern Gulf of Mexico
provides a tight pressure gradient across the western Gulf. Will
go ahead and extend the SCA for the bay waters through this
evening and post an SCA for the offshore for this evening through
Fri morning. The pressure gradient will remain strong across the
coastal waters Friday and small craft advisories will be needed
for the Laguna Madre Fri morning and the SCA for the offshore
waters may need to be extended possibly through Fri afternoon.
Small craft advisories will be needed for the offshore waters for
Fri night for strong southeast winds.

Saturday through Tuesday night: A persistent pattern of high
pressure will dominate the Gulf during this period. Thus, look for
mainly moderate southeast winds and seas. Seas of four to six feet
will be common offshore, qualifying for small craft should exercise
caution headlines.

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory until 7 AM CDT this morning for GMZ150-155-
     170-175.

&&

$$

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