796
FXUS64 KBRO 172312 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
612 PM CDT Thu Sep 17 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 606 PM CDT Thu Sep 17 2026

- A Special Weather Statement is in effect for the inland Coastal
  Counties for elevated heat indices this afternoon.

- There is a low to moderate (20 to 40%) chance of showers and
  thunderstorms across Deep South Texas today and tomorrow.

- Moderate (level 2 of 4) to Major (level 3 of 4) Heat Risk will
  continue to remain a concern over the next week.

- Conditions should be drier for the weekend, but low to moderate
  rain chances return early next week.

&&

.DISCUSSION...
Issued at 1222 PM CDT Thu Sep 17 2026

An unsettled weather pattern continues over the next few days as an
area of strong high pressure over the Southeastern CONUS backbuilds
westward, with northeasterly upper level flow beneath the underside
of of this high reaching Deep South Texas.  Because this
northeasterly airmass has spent considerable time over the Gulf,
the atmospheric profile is expected to remain deeply moist for
the next few days, with PWATs increasing to over 2 inches. This
will support low to moderate (20 to 40%) rain chances today and
tomorrow. The rain is expected to be overall beneficial, with most
areas receiving no more than half an inch. However, some heavier
showers and thunderstorms could cause locally higher amounts with
the potential for nuisance ponding.

As high pressure continues to build westward over northeastern Texas
though the weekend, upper-level subsidence should help dry out
conditions for the weekend. A shower or two cannot be ruled out
along the sea breeze, but rain chances remain below 20% for both
Saturday and Sunday. Rain chances are expected to pick up again next
week as high pressure and subsidence weaken but with continued
east-northeasterly moist upper-level flow. Sea breeze activity is
possible each day next week (mostly east of I-69C), and some
longer-range guidance hints at a pattern shift/potential
shortwave disturbance later next week that could bring widespread
low to moderate rain chances to all of Deep South Texas.

Heat Risk will remain a concern over the next week.  Though
increased cloud cover and rain chances may bring some small
temperature relief by a few degrees, the humid airmass will continue
to keep heat indices high.  A Special Weather Statement is in effect
today for the inland Coastal Counties, where Heat Indices could
reach between 108-111 degrees this afternoon.  Moderate (level 2 of
4) to Major (level 3 of 4) Heat Risk is expected to continue
throughout the next week.

&&

.AVIATION...
(00Z TAFS)
Issued at 606 PM CDT Thu Sep 17 2026

Gentle to moderate east-northeasterly winds this evening become
light and/or variable overnight tonight before returning tomorrow
afternoon. A brief period of light rain or two is possible
overnight at KHRL and KBRO, with the best chances tomorrow
morning before spreading east to KMFE tomorrow afternoon. Brief
light to moderate, perhaps isolated heavy, passing showers may
intermittently reduce visibility, leading to possible short
periods of MVFR as noted in the PROB30s.

&&

.MARINE...
Issued at 1222 PM CDT Thu Sep 17 2026

Favorable conditions are expected over the next several days with
light to moderate northeasterly winds and low to moderate (2 to 4
feet) wave heights. Offshore showers and thunderstorms are
possible throughout the next week, which could temporarily
deteriorate conditions in their immediate vicinity.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             79  95  78  95 /  20  20  10  20
HARLINGEN               76  97  74  98 /  30  20  10  10
MCALLEN                 79  98  77  99 /  10  30  10  10
RIO GRANDE CITY         78  98  75 100 /  30  20  10   0
SOUTH PADRE ISLAND      81  88  81  88 /  30  30  20  10
BAYVIEW/PORT ISABEL     78  94  77  94 /  30  30  10  10

&&

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

$$

SHORT TERM...55-MM
LONG TERM....55-MM
AVIATION...65-Irish