662
FXUS64 KBRO 121725
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1225 PM CDT Tue Aug 12 2025

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

.KEY MESSAGES...
Updated at 1225 PM CDT Tue Aug 12 2025

 - Daily low precipitation chances (20% or less) along the sea
   breeze each afternoon through Thursday.

 - Influx of tropical moisture will bring low to medium
   precipitation chances (20-40%) Friday and Saturday, with the
   highest chances along/east of US-281/I-69C.

 - Moderate (level 2 of 4) to major (level 3 of 4) heat risk
   continues for most of Deep South Texas. Continue to practice
   heat safety!

&&

.DISCUSSION...
Issued at 1225 PM CDT Tue Aug 12 2025

The overall upper air pattern remains largely unchanged, with two
areas of high pressure centered over the Desert Southwest and
Southeastern US, respectively. Persistent low level southerly to
southeasterly flow maintains elevated moisture content, especially
along the immediate coast. In combination with diurnal heating
and weak forcing along the sea breeze, isolated showers and
thunderstorms cannot be ruled out each afternoon through Thursday.
Most activity that develops will be capable of gusty winds,
lightning, and brief heavy rainfall, and should diminish with the
loss of daytime heating.

By the end of the week and first half of the weekend, model
guidance continues to indicate slightly better opportunities for
rain chances region wide as a tropical wave translates toward the
region. This will also bring an influx of tropical moisture, with
precipitable water values increasing to around or upwards of
2.2-2.3 inches Friday and Saturday. All in all, there should be an
uptick in coverage of showers and thunderstorms along and east of
US-281/I-69C on Friday and across most of Deep South Texas on
Saturday. Precipitation chances range from low to medium (20-40%)
at this time, with the highest chances coinciding with the highest
moisture content. Efficient rain-producing showers and
thunderstorm may result in minor/nuisance flooding issues, mainly
across low-lying or flood-prone roads or areas. Expect additional
adjustments to the forecast as model guidance comes into better
agreement and begins to be captured by high res guidance.

Otherwise, a moderate to major heat risk will continue through
most of the week for all of Deep South Texas as highs warm into
the mid to upper 90s to around 103 degrees and heat index values
ranging from 105 to 111 degrees each afternoon. Well continue to
keep an eye on the potential for Heat Advisories. Continue to
practice heat safety to prevent heat-related illness and always
check the backseat before leaving your car.

&&

.AVIATION...
(18Z TAFS)
Issued at 1225 PM CDT Tue Aug 12 2025

VFR and southeast winds will prevail through the forecast period
at all TAF sites. Occasional gusts to 15-20 knots cannot be ruled
out during the afternoon hours. Otherwise, isolated convection may
develop along the sea breeze this afternoon but confidence in
location is too low to warrant a mention at this time.

&&

.MARINE...
Issued at 1225 PM CDT Tue Aug 12 2025

Generally favorable marine conditions will prevail through next
week with light to moderate southeast winds and low to moderate
seas. Isolated to scattered showers may develop each morning over
the Gulf waters. Low to medium precipitation chances (20-40%)
return Friday and Saturday over the Gulf waters and Laguna Madre.
Expect locally enhanced winds and seas within any showers and
thunderstorms.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             97  80  97  80 /  20   0  20   0
HARLINGEN               99  75  99  76 /  20   0  20   0
MCALLEN                103  80 103  79 /  20  10  20   0
RIO GRANDE CITY        103  78 104  78 /  10  10  10  10
SOUTH PADRE ISLAND      89  81  89  82 /  10   0  10   0
BAYVIEW/PORT ISABEL     93  78  95  79 /  10   0  20   0

&&

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

$$

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