786
FXUS64 KBRO 111718
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1218 PM CDT Mon Aug 11 2025

...New DISCUSSION, AVIATION, MARINE...

.DISCUSSION...
Issued at 1212 PM CDT Mon Aug 11 2025

Convergence along seabreeze boundaries, diurnal instability and weak
forcing over deep south Texas are likely to continue to generate a
near daily low (20-30%) chance of brief isolated showers and
thunderstorms along and east of I-69 C as the region continues to be
wedged between a mid-level high pressure over the Desert Southwest
and another over the southern and southeastern US. Heavy downpours,
lightning and stronger gusts are possible within the strongest of
convection. Although subject to change, we currently anticipate the
best coverage of convection to fall on Wednesday and Friday as a
series of weak inverted troughs pass over the region as well less
than a 15% chance on Thursday. As the week progresses, the mid-level
high to the east is expected to slowly expand and shift westward
across the Gulf Coast, increasing subsidence aloft and reducing
probabilities of showers and thunderstorms to less than 15%,
possibly by Saturday and into the beginning of next week.

Temperatures are likely to remain near to a few degrees above
average, with afternoon highs in the mid to upper 90`s east of I-69
E and near or above 100 degF to the west as well as mid 80`s to the
mid 90`s along and near the coast (coolest along the immediate Gulf
Coast) while overnight lows in the 70`s inland and lower 80`s at the
coast continue. Meanwhile, surface high pressure dominating the Gulf
maintains southeasterly winds, pumping moisture into the region,
resulting in persistent humid conditions and afternoon heat indices
generally ranging between 100-110 degF throughout the period.
Special Weather Statements, and/or a brief Heat Advisory, may be
possible over the weekend as reduced cloud coverage and increased
humidity could cause indices to reach or top 111 degF for a brief
period of time in the afternoon across portions of the CWA.
Otherwise, a mainly moderate (level 2/4) heat risk continues through
next Monday. Pockets of major (level 3/4) heat risks are likely
across the Rio Grande Valley and coastal counties, possibly
expanding in area on Thursday and Saturday.

&&

.AVIATION...
(18Z TAFS)
Issued at 1212 PM CDT Mon Aug 11 2025

A moderate east-southeasterly to southeasterly breeze, gusting up
to 15-20 knots, is likely to persist through the rest of this
afternoon and into this evening, settling down to a light breeze
(5-10 knots) overnight. There is a low (20-30%) chance of isolated
showers and thunderstorms this afternoon, which could briefly
reduce ceilings and visibility down to MVFR. Otherwise, VFR
conditions prevail with winds picking back up to moderate early
Tuesday afternoon.

&&

.MARINE...
Issued at 1212 PM CDT Mon Aug 11 2025

Surface high pressure over the Gulf continues to result in mostly
favorable marine conditions with a gentle to moderate southeasterly
to southerly breeze and slight to moderate (1-3 feet) seas. There is
a low to medium (20-40%) chance of brief showers and thunderstorms
during the daytime Wednesday through Friday, with the highest
probabilities over the eastern offshore (20-60 nm) Gulf waters.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             79  96  79  96 /   0  20  10  20
HARLINGEN               75  98  75  98 /   0  20   0  20
MCALLEN                 79 102  79 102 /  10  20  10  20
RIO GRANDE CITY         78 103  78 102 /  10  20  10  10
SOUTH PADRE ISLAND      81  88  81  89 /   0  10  10  10
BAYVIEW/PORT ISABEL     78  94  78  94 /   0  10   0  20

&&

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

$$

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