488
FXUS64 KBRO 190826
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
324 AM CDT Sun May 19 2024

...New SHORT TERM, LONG TERM, MARINE...

.SHORT TERM...
(Today through Monday)
Issued at 322 AM CDT Sun May 19 2024

500 mb high pressure centered along the west coast of Mexico will
build northeast during the period, and will become more dominant
over the BRO CWFA. This will have the effect of not only producing
dry weather, but also well above normal, and increasing,
temperatures. Heat index values will max out between 103 and 108
degrees today, and from 105 to 110 degrees for Monday with a
couple of very isolated values of 111 degrees. As a result, a Heat
Advisory is not anticipated to be needed for any portion of Deep
South Texas and the Rio Grande Valley during the Short Term
forecast period. Will likely cover the higher heat indices on
Monday with a Special Weather Statement at that time.

&&

.LONG TERM...
(Monday night through Saturday)
Issued at 322 AM CDT Sun May 19 2024

A broad 500 mb ridge centered over northern Mexico will extend into
Deep South Texas and the Rio Grande Valley leading to hot
temperatures through the period. At the surface, steady southeast
winds, breezy at times, will allow for plenty of low-level moisture
flow to move into the region and thus keeping the very humid airmass
in place. The combination of lack of deep moisture and subsidence
will maintain rain-free conditions across region through the long
term.

Dangerous heat will be the main concern through the week and into
Memorial Day Weekend. Temperatures are expected in the triple digits
across the Rio Grande Plains Tuesday afternoon with mid to upper 90s
across the rest of the area, except for the 80s near the coast. The
triple digit heat will expand farther eastward through the week,
reaching the I-69c/US 77 corridor on Wednesday. High humidity
combined with the hot surface temperatures will lead to "feels like"
temperatures exceeding 110 degrees at many locations and Heat
Advisories may be needed on Tuesday. However, Heat Advisories will
be more likely later in the week as the heat indices over 111
degrees become more widespread across the area, especially Friday
into the next weekend. The latest NBM suggests that the max heat
index around 116 degrees will be possible for a few locations Friday
and into the Memorial Day weekend. Thus, Excessive Heat Warnings and
Watches may be needed during that time. Overnight temperatures each
night will remain warm with lows falling into the upper 70s to low
80s.

There is a Moderate to Major risk of heat-related impacts for anyone
without effective cooling and/or adequate hydration with heat
indices ranging up to around 111 degrees for Tuesday through
Thursday. Friday and especially into Saturday, a more widespread
Extreme heat risk with heat indices 111-115+ degrees across much of
Deep South Texas. This level of rare and/or long-duration extreme
heat with little to no overnight relief affects anyone without
effective cooling and/or adequate hydration.

In addition, fair to poor air quality is expected to prevail through
the long term for much of the Rio Grande Valley due to agricultural
burning in southeast Mexico/Yucatan and Central American wildfires
all being driven north/northwestward on the persistent south to
southeast flow.

&&

.AVIATION...
(06Z TAFS)
Issued at 1222 AM CDT Sun May 19 2024

MVFR to VFR will prevail at the aerodromes through the next 24
hours. Light to moderate winds with no precipitation is also
anticipated.

&&

.MARINE...
Issued at 322 AM CDT Sun May 19 2024

Today through Monday: Buoy 42020 reported east winds around 10
knots gusting to around 12 knots with seas slightly under 4 feet
with a period of 7 seconds at 250 CDT/750 UTC. A modest pressure
gradient will exist along the Lower Texas Coast through the
period, with high pressure dominating over the western Gulf of
Mexico. Light to moderate winds and low to moderate seas are
forecast, and neither Small Craft Should Exercise Caution nor
Small Craft Advisory are anticipated to be needed.

Monday night through Thursday night: Weak to moderate onshore flow
with generally moderate seas will persist through the period. A
locally enhanced pressure gradient could lead to Small Craft Caution
conditions on the Laguna Madre each afternoon into the early evening
on the Laguna Madre and the nearshore Gulf waters, Tuesday through
Saturday. Additionally, seas will slightly build Wednesday through
late week and may lead to Small Craft Exercise Caution conditions on
the offshore Gulf waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             94  79  95  80 /   0   0   0   0
HARLINGEN               95  75  97  77 /   0   0   0   0
MCALLEN                 99  78 100  80 /   0   0   0   0
RIO GRANDE CITY         99  77 100  78 /   0   0   0   0
SOUTH PADRE ISLAND      86  80  86  81 /   0   0   0   0
BAYVIEW/PORT ISABEL     89  78  92  79 /   0   0   0   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

SHORT TERM...66-Tomaselli
LONG TERM....63-KC
AVIATION...66-Tomaselli