122
FXUS64 KBRO 191927
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
227 PM CDT Sun May 19 2024

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

.SHORT TERM...
(Tonight through Monday night)
Issued at 148 PM CDT Sun May 19 2024

The main weather story will continue to be the building heat
through the short-term period and beyond. This is due to a
mid/upper level ridge axis anchored across Mexico expanding into
Texas and the remainder of the Southern Plains over the next few
days. Strong subsidence and limited moisture depth will keep a
rain-free forecast going. It does appear that we will have one
more day on Monday where heat advisory criteria (111 degree heat
indices) will be just shy of being met for most of the area. A
few isolated locations will likely reach 111 heat index or just
exceed it for an hour or two but not long enough or widespread
enough to warrant a heat advisory at this time for Monday. Heat
indices will generally peak between 105 and 110 degrees on Monday.

Geocolor satellite imagery continues to depict the core of the
agricultural smoke/haze over the open Gulf with the periphery of
this affecting portions of our CWA. Based upon the RAP-Smoke and
GEOS-5 models forecast of vertically integrated smoke and total
aerosols, have decided to add haze to the weather grids through
Monday.

&&

.LONG TERM...
(Tuesday through next Sunday)
Issued at 148 PM CDT Sun May 19 2024

Key Messages:

- Above normal temperatures and heat index values are expected
across Deep South Texas this week and Memorial Day weekend.

- The combination of above normal temperatures and humidity will
yield dangerous heat index values in the 110-120 degree range during
the day, and in the upper 80s to low 90s overnight.

- There will be an increased risk of heat related impacts,
especially those that do not take adequate breaks in the shade or
stay hydrated.

- Poor air quality will continue through the week for most of the
region.

Mid/upper level ridging centered over Mexico will maintain rain-free
conditions and above normal temperatures across Deep South Texas
into Memorial Day weekend. Meanwhile, persistent low level southerly
to southeasterly flow will result in continued humid conditions at
the surface. In addition to the heat and humidity, low level winds
will continue to transport smoke associated with agricultural
burning in southeast Mexico, which will maintain poor air quality
across portions of the region.

A steady increase in temperatures is expected through the week and
into the weekend as the ridge continues to build, with afternoon
high temperatures ranging from the mid to upper 80s along the Lower
Texas beaches, mid to upper 90s along/east of I-69, and above 100
degrees (100-106 degrees) west of I-69. In combination with the
humidity, "feels like" temperatures will range from upper 90s along
the Lower Texas beaches to around 112 degrees through Thursday, and
closer to 114-118 degrees Friday through the weekend, across the
Northern Ranchlands and Rio Grande Valley. In comparison to the
early May heat wave, one notable difference is the forecast of
higher minimum temperatures each night... with most of the Rio
Grande Valley expected to observe low temperatures in the low 80s.
In combination with the high dew points in place, there won`t be
much relief from the heat overnight as "feels like" temperatures
remain in the upper 80s and low to mid 90s.

This will result in a major to extreme risk of heat-related impacts,
especially towards the end of the week and into the weekend. Staying
properly hydrated, limiting time spent outdoors during the peak
heating of the day, taking frequent breaks in the shade, and wearing
light-colored, loose-fitting clothing will be necessary to prevent
any heat related illnesses.

Heat headlines may be needed for portions of the region Wednesday
and Thursday, and will likely be needed this Memorial Day weekend.
Regardless of the issuance of any heat products (Heat Advisory,
Excessive Heat Warning), the prolonged period of oppressive daytime
and nighttime temperatures will limit the ability to recover from
the heat, especially if spending several hours outside during the
day. If you have any outdoor plans this weekend for Memorial Day or
attending outdoor graduation ceremonies, make sure you are taking
the oppressive heat into account.

&&

.AVIATION...
(18Z TAFS)
Issued at 1122 AM CDT Sun May 19 2024

Thermal mixing has allowed most areas to rise to the VFR category
as of 16Z today. By 18Z this afternoon, all RGV TAF sites are
expected to be at the VFR category and remain at that level
through around 03-04Z. By that time in the evening, MVFR low
clouds will once again begin developing across the RGV TAF sites.
Much less fog is expected tonight given the less favorable
slightly stronger southeast flow. Could still see patchy IFR
conditions but overall we are anticipating MVFR conditions through
tonight and persisting into the morning hours.

Widespread haze reducing visibilities at times to 4-6 miles will
continue to affect at least the KBRO and KHRL TAF sites through
the period and beyond.

&&

.MARINE...
Issued at 148 PM CDT Sun May 19 2024

Tonight through Monday night...Generally weak onshore flow will
continue tonight. However 3-4 ft swells will persist but are
expected to slowly decay through the short-term. Overall, this
will tend to maintain a moderate risk of rip currents through
tonight with a borderline moderate risk of rips on Monday. The
flow will continue to veer through Monday as a more
climatologically normal return flow setup establishes itself. A
bit more in the way of a moderate onshore flow as a result will
establish itself by Monday afternoon and continue through Tuesday
morning. Seas will slowly respond and build back to 4 ft overnight
on Monday.

Tuesday through Saturday...Light to moderate winds and moderate seas
are expected through the weekend. A locally enhanced pressure
gradient may result in a brief period of Small Craft Exercise
Caution conditions each afternoon on the Laguna Madre and nearshore
Gulf waters. Small Craft Exercise Caution conditions will extend to
the offshore Gulf waters Thursday and Friday due to increased winds
and seas slightly building.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             79  95  80  94 /   0   0   0   0
HARLINGEN               75  97  77  97 /   0   0   0   0
MCALLEN                 78 100  79  99 /   0   0   0   0
RIO GRANDE CITY         77 100  77 101 /   0   0   0   0
SOUTH PADRE ISLAND      80  86  81  86 /   0   0   0   0
BAYVIEW/PORT ISABEL     78  92  79  92 /   0   0   0   0

&&

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

$$

SHORT TERM...80-MB
LONG TERM....22-Garcia
AVIATION...80-MB