Area Forecast Discussion
Issued by NWS Brownsville, TX

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FXUS64 KBRO 270551 AAB
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1251 AM CDT Wed Oct 27 2021

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

&&

.AVIATION...Breezy to gusty southeasterly winds are hanging in
there across the Rio Grande Valley this evening, and will only
back off slightly in the next few hours. MVFR ceilings will impact
all three TAF sights overnight, but VFR conditions will prevail
for the rest of the period. A cold front will move through mid
morning into the early afternoon, bringing gusty and windy
northerly winds and clearing skies.

&&

.PREV DISCUSSION... /issued 624 PM CDT Tue Oct 26 2021/

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...VFR conditions now with breezy and gusty to strong
southeast winds. Winds will decrease later this evening but will
remain moderate to breezy overnight ahead of a cold front due in
the lower Valley late Wednesday morning to early afternoon. Brief
MVFR ceilings will be possible overnight as winds decrease. Winds
will switch to moderate northwest Wednesday afternoon behind the
front. A few showers may occur along the front near the coast. BKN
to OVC low clouds will scatter out with the arrival of much drier
air moving in behind the front.

PREV DISCUSSION... /issued 256 PM CDT Tue Oct 26 2021/

SHORT TERM (Tonight through Wednesday Night): For the first half
of the short term period, temperatures will be above normal still
with a warm and muggy Tuesday evening with mostly cloudy skies. A
500mb trough across the western United States works its way east
through Texas bringing a weak cold front to the area. This front
is bringing a slightly cooler and drier airmass into the area with
little to no precipitation with it. There is good model agreement
with the timing of the incoming front arriving as early as
Wednesday afternoon.

Winds start to shift northwesterly as dewpoint temperatures plummet
into the 30s and 40s starting with the western counties of Zapata
and Jim Hogg first and slowly working its way southeast to Cameron
county by Wednesday afternoon. Deep South Texas will still be very
hot on Wednesday with an increase in wind speed following the
frontal passage. The dry airmass combined with gusty north to
northwesterly winds will produce conditions for erratic wildfire
behavior to all of the CWA. Currently, SPC has all of Deep South
Texas and Rio Grande Valley in a Critical Risk category for the
Day 2 Fire Weather Outlook. A Red Flag Warning has been issued for
all of the counties in the CWA from Wednesday afternoon until the
evening hours (15z-00z). Wednesday night will be pleasant as
northwesterly winds die down with dewpoints in the mid 30s and low
temperatures 10 degrees cooler than the previous night in the mid
60s.

LONG TERM (Thursday through Tuesday): The 500 mb trough that will bring a
cold front through Deep South Texas Wednesday will move off to the
east on Thursday. Northwesterly flow aloft will continue as a
surface ridge builds over the region through the end of the week
bringing much drier air to the area into the weekend. Afternoon high
temperatures behind the front will drop to near or just below normal
through Saturday with overnight lows falling to 5 to 10 degrees
below normal for most locations.

Late Saturday into Sunday, the surface ridge will begin to break
down, midlevel flow will become quasi-zonal and onshore flow will
redevelop. This will allow for dewpoints to increase across the
area late this weekend into early next week. While moisture
returns to the area, the forecast will remain dry through much of
the period with only slight POP chances returning for coastal
areas late Tuesday. Afternoon high temperatures and overnight lows
will begin to creep back up to just above seasonal norms early
next week.

MARINE (Tonight through Wednesday Night): A Small Craft Advisory
is in effect for the Laguna Madre and Gulf Waters for Wednesday
as the pressure gradient tightens and winds increase and turn
northwesterly in the wake of an incoming cold front. Seas will
build up to 6 feet on Wednesday. As winds begin to die down after
the frontal passage, seas will still be moderate and a Small Craft
Advisory still may be needed for Wednesday night.

Thursday through Sunday...Favorable conditions will gradually
return across the Gulf waters and the Laguna Madre through the
period. In wake of a cold front A Small Craft Advisory may be
needed for the offshore Gulf waters into midday Thursday with
continued gusty winds. Otherwise, small craft may need to
continue to exercise caution on the Gulf waters into Friday before
high pressure settles in across the area with winds and seas
decreasing. Winds will remain northerly through Friday night and
then become easterly and then southeasterly over the weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  94  62  83  61 /  10   0   0   0
BROWNSVILLE          98  61  86  60 /  10   0   0   0
HARLINGEN            97  59  86  57 /  10   0   0   0
MCALLEN              98  59  88  58 /   0   0   0   0
RIO GRANDE CITY      98  57  90  55 /   0   0   0   0
SOUTH PADRE ISLAND   89  71  80  70 /  20   0   0   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Red Flag Warning from 10 AM this morning to 7 PM CDT this
     evening for TXZ248>257-351-353.

GM...Small Craft Advisory from 4 AM early this morning to 7 PM CDT
     this evening for GMZ130-132-135.

     Small Craft Advisory until 7 PM CDT this evening for GMZ150-155-
     170-175.

&&

$$

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Aviation Update...69-Farris


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