Brownsville, Texas 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

366
FXUS64 KBRO 052320
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
620 PM CDT Fri Sep 5 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 618 PM CDT Fri Sep 5 2025

 - Hot and rain-free conditions with Moderate (level 2 of 4) to
   Major (level 3 of 4) Heat Risk continues through Saturday.

 - Widespread wet and unsettled weather pattern returns for the
   weekend and early next week.

 - Expected rainfall totals remain highly uncertain, however WPC
   continues to maintain a marginal risk (level 1 of 4) for
   Excessive Rainfall Sunday through Sunday night.

.DISCUSSION...
Issued at 1213 PM CDT Fri Sep 5 2025

The main story for the forecast period continues to be the elevated
chances for rain starting tomorrow and continuing through the early
part of next week. Current model guidance does show that there is a
large plume of moisture that will make its way into Deep South Texas
and the Rio Grande Valley. This will allow for PWATs to be around 2
inches starting this weekend and continuing through the early part
of the week. Meanwhile, a frontal boundary is expected to stall out
to the north of the region. With southeasterly to easterly flow on
the surface, there will be plenty of low-level moisture in the
region to foster the development of showers and thunderstorms over
the region. There are several factors to this rainfall event that
bring a lot of uncertainty to the forecast. Notably, how far south
the front comes down will be a major factor as the further south the
front comes down the greater chances for rain would be for the
region. However, if the front stays further north, the chances for
rain could drop for the area. While the NBM 50th percentile
continues to suggest possible rainfall totals of 1.5 to 3 inches or
greater by Wednesday morning. While the NBM is a blend of different
forecasting models, there are some models that sit on the extremes
of this rainfall event adding in a lot of uncertainty to how much
rainfall could occur. Given the amount of uncertainty in the
forecast, it is hard to say which locations are likely to be
impacted the most at this time. With so much uncertainty in the
forecast, a blend of the NBM, GFS, and ECMWF were used to lower PoPs
and to reduce some of the bias that is in the NBM blends. Until we
can get more CAMs involved in the model blends, there will still be
a lot of uncertainty in the forecast. Any sort of persistent rain
over any area could lead to some localized flooding especially for
places in low-lying areas and other flood prone regions. It should
also be noted that given the high amount of moisture in the
environment, it is possible for some of these showers and
thunderstorms to produce a high amount of rainfall in an area in a
very short time, that could also lead to some localized flooding as
well. With all these factors combined, WPC maintains a marginal risk
(level 1 of 4) for excessive rainfall for Deep South Texas and the
Rio Grande Valley.

As for the temperatures in the forecast period, the highs for today
and tomorrow are expected to mostly be in the triple digits for the
region with areas along the coast could be in the upper 90s.
However, moving into the weekend and the rest of the forecast
period, temperatures are expected to decrease a bit due to the cloud
coverage over the area. Limiting the highs to mid to upper 90s for
the area. Low temperatures are expected to mostly remain in the 70s
for the forecast period as well.

&&

.AVIATION...
(00Z TAFS)
Issued at 618 PM CDT Fri Sep 5 2025

VFR condition expected at all airports with some possible high
clouds around 18z. Winds are expected to be light to moderate and
southeasterly for the duration of the forecast period.

&&

.MARINE...
Issued at 1213 PM CDT Fri Sep 5 2025

Mostly favorable marine conditions are expected for the forecast
period with light to moderate southeasterly to easterly winds and
low to moderate seas. Showers and thunderstorms are expected to be
more likely this weekend and through the early part of next week. A
frontal boundary is expected to stall out towards the north of the
Lower Texas Coast. Depending on how far north the front stalls out,
will impact the chances for rain.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             96  80  96  80 /  10  20  30  30
HARLINGEN              100  76  98  75 /  10  20  30  30
MCALLEN                103  81 102  80 /   0   0  30  20
RIO GRANDE CITY        104  78 102  78 /   0   0  20  20
SOUTH PADRE ISLAND      90  83  90  83 /  10  40  30  40
BAYVIEW/PORT ISABEL     95  79  94  78 /  10  20  30  40

&&

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

$$

SHORT TERM...64-Katz
LONG TERM....64-Katz
AVIATION...55-MM