519
FXUS64 KBRO 311723
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1223 PM CDT Sun Aug 31 2025

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

.KEY MESSAGES...
Updated at 1216 PM CDT Sun Aug 31 2025

-Heat continues to be a concern especially for tomorrow with a
 Moderate (level 2 out of 4) to Major (level 3 out of 4) Heat
 Risk.

-Rain chances increase for tomorrow and Tuesday.

-The Weather Prediction Center continues to highlight northern
 portions of Zapata, Jim Hogg, Brooks, and Kenedy counties in a
 Marginal Risk (level 1 of 4) of excessive rainfall for tomorrow.


&&

.DISCUSSION...
Issued at 1216 PM CDT Sun Aug 31 2025

The main concern for the remainder of the holiday weekend continues
to be the heat. As a mid-level ridge continues to linger over Deep
South Texas and the Rio Grande Valley, and low-level southerly to
southeasterly flow continues bring in more low-level moisture into
the region. These factors result in higher temperatures and higher
heat indices as well. With nearly a majority of the CWA in a major
(level 3 of 4) heat risk, and the rest of the region in a moderate
(level 2 of 4). With the range of the heat indices in the range of
105 to 110 for today and  tomorrow, additional Special Weather
Statements could be issued for elevated heat indices. For resources
on staying safe in the heat, visit weather.gov/heatsafety.

With the previously mentioned mid-level ridge over the area, the
chances for rain will remain low (less than 20%) for today. However,
a frontal boundary is expected to move southward and stall towards
the north of the CWA by tomorrow afternoon. With the southerly to
southeasterly low-level moisture flow expected at this time, there
will be an opportunity for moisture to pool ahead of the boundary
and allow for the development of showers and thunderstorms. Add in
some instability from the diurnal heating as well, and the
environment is capable of producing some showers and thunderstorms.
Current rain chances for tomorrow afternoon and Tuesday remain
around medium (40-50%). WPC has a small portion of the Northern
Ranchlands in a marginal risk (level 1 of 4). While the
environmental conditons seem favorable, the key to the forecast for
the rain will be where the frontal boundary stalls out. Should the
frontal boundary stall out further north, then the chances for rain
will decrease for tomorrow and Tuesday afternoon. Further updates on
this developing situation are expected.

The frontal boundary is expected to finally move through the region
Tuesday afternoon. At this point, the temperatures are not expected
to change much with this frontal passage, but the winds are expected
to shift towards the north after the frontal passage. Most of next
week generally has low rain chances (less than 30%). Most showers
and thunderstorms will be related to any sort of seabreeze activity.
There is some model guidance that suggests that another front may
try to move through the region late next week. The latest model
guidance does bring the chances of rain up to a medium chance (40-
60%) for next weekend, however further forecast shifts will need to
continue to monitor the model trends to see how the forecast
continues to evolve.

&&

.AVIATION...
(18Z TAFS)
Issued at 1216 PM CDT Sun Aug 31 2025

VFR conditions are expected to persist through the TAF cycle at
all TAF sites. Southerly to southeasterly winds are expected for
the period and should generally remain light. Some low-level
clouds are expected as well with the current flow pattern.

&&

.MARINE...
Issued at 1216 PM CDT Sun Aug 31 2025

Generally favorable conditions with mostly light to moderate
southerly to southeasterly winds and low to moderate seas. Medium
chances (40-50%) of rain are expected for tomorrow afternoon and
Tuesday as a frontal boundary stalls out towards the north. By
late Tuesday into Wednesday, the front is expected to push through
in the Lower Texas Coast and the winds are expected to turn to
towards the north while remaining light to moderate. The winds
should return to the south fairly quickly.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             79  95  79  95 /  10  40  40  70
HARLINGEN               75  97  75  95 /   0  50  50  70
MCALLEN                 79 101  79  97 /   0  40  50  70
RIO GRANDE CITY         77 101  77  96 /   0  30  60  60
SOUTH PADRE ISLAND      82  89  80  88 /  10  40  50  60
BAYVIEW/PORT ISABEL     78  93  77  92 /  10  40  50  60

&&

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

$$

SHORT TERM...64-Katz
LONG TERM....64-Katz
AVIATION...64-Katz