148
FXUS64 KBRO 031818
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
118 PM CDT Sun Aug 3 2025

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

.KEY MESSAGES...
Updated at 100 PM CDT Sun Aug 3 2025

* Relentless heat, some of the hottest temps of the year, and dry
  conditions will prevail through next weekend.

* HeatRisk will range between Moderate (Level 2 of 4) and Major
  (Level 3 of 4) through next weekend.

* Triple digit heat will be widespread and common along and west of
  IH-69E most days; heat indices will range between 105-115F degrees
  through this week.

* Low, non-zero probability (10-30%) of an isolated shower or
  thunderstorm this afternoon/evening; additional chances
  possible this week, primarily along and east of IH-69C.

* Generally favorable marine conditions will continue with low to
  moderate winds and seas, and mainly low rip current risk. Low
  (10- 30%) chances of showers and thunderstorms over the Gulf
  Waters this week.

&&

.DISCUSSION...
Issued at 100 PM CDT Sun Aug 3 2025

Relentless (record to near record-breaking) heat, humid, mostly rain-
free, and at times breezy conditions with elevated cooling
demand/cooling degree days (CDDs) will continue to be the
main headline through the forecast period or through next
weekend. After yesterday`s record setting day at all three climate
sites, some of the hottest temperatures of the season are
expected to take place once again today, coinciding with peak
climatological temperature averages. While an elongated 591 dam
subtropical heat complex will envelope the Southern U.S. through
next weekend, forecast models and ensembles continue to depict an
anomalously strong and sprawling 594-600 dam subtropical Sonoran
heat dome (+2 to +4 STDEVs) over the Desert Southwest, at times
extending into Oklahoma and the west-northwestern half of Texas.
This feature is expected to weaken slightly early this week before
strengthening over the Desert Southwest U.S. into West Texas
going towards the middle parts of this week.

As mentioned, some of the hottest temperatures of the year are
expected to take place once again today and possible again later
this week. That`s when the Sonoran heat ridge "heat dome" will be
the most expansive across the Southwestern U.S. into the Plains.
Over Deep South Texas and the Rio Grande Valley, sampled 500 mb
heights will range between 591-595 dam. Meanwhile, sampled 1000-500
mb thickness heights are expected to range between 580-584 dam.
850 mb temperatures ranging between 21-23C will translate to sfc
high temperatures ranging between 95-106F degrees each day through
next weekend.

Triple digit heating will be widespread encompassing a vast majority
of real estate across Deep South Texas and the Rio Grande Valley,
basically extending from IH-69E and points west, nearly each day.
Today will be similar to Saturday as far as the magnitude of the
heat and again looks to be one of the hottest days of the forecast
period. We will continue to monitor temperature trends during the
middle parts of this week (Wednesday and/or Thursday) as potential
hottest days of the period candidates as the aforementioned heat
ridge strengthens and expands again, and potentially reach peak
magnitude. Daytime high temperatures along South Padre Island and
beaches along the Texas Coast are progged to continue to be in
the upper 80s to near 90F degrees.

Given the very humid, tropical-like environment, heat indices will
generally range between 105-115F degrees each day through next
weekend. Special Weather Statements (SPSs) are in place today for
Starr, Kenedy, Willacy, Cameron and Hidalgo Counties. Our first Heat
Advisories of the season and to a greater extent (degree of
confidence) additional Special Weather Statements (SPSs) may be
needed at times to acknowledge these hot temperatures through next
weekend. Given these hot temperatures, Moderate (Level 2 of 4) and
Major (Level 3 of 4) HeatRisk will be common through the forecast
period.

To learn more about HeatRisk, visit wpc.ncep.noaa.gov/heatrisk/. To
learn more about heat in general, visit www.heat.gov. Finally, we
urge everyone to take the necessary measures to protect yourself
from the heat. Heat is the #1 cause of weather related deaths,
nationally and for that matter globally. Drink plenty of water, take
frequent breaks, stay in a cool, air- conditioned location/shelter,
and check on your family, friends, elderly, neighbors, and pets.

While rain-free conditions, by and large, will prevail through the
forecast period, courtesy of the anomalously strong 594-600 dam
Sonoran heat dome in place driving strong subsidence over the
region, day-to-day chances or near day-to-day chances for showers
and thunderstorms along the seabreeze is possible. Despite the lack
of upper air/jet stream dynamics, the extremely hot temperatures
breaching Convective Temperature levels enhancing updraft ability
and a nearby frontal boundary (in CRP area), albeit weak, could
trigger an isolated showers/thunderstorm.

That said, after further analysis of hi-res (convective allowing
models) CAM guidances and collaboration with CRP, have decided to
bump up PoPs slightly this afternoon/evening to 15-30%.
Additional opportunities for showers and storms are possible this
week. Will continue to monitor trends in the coming days. Any
convection this week will largely be due to temporary weakness in
the 500 mb pattern. Right now, the best chances look to be on
Tuesday. For now have continued to implement low grade (20%)
chances for a shower or thunderstorm to develop on Tuesday from
IH-69C and points east to the Texas coast. Also have low grade
PoPs for Wednesday along and east of IH-69C for now.

Rip current risk will mainly be low through the period, but there
could be instances of moderate rip current risk and breezy
conditions.

&&

.AVIATION...
(18Z TAFS)
Issued at 100 PM CDT Sun Aug 3 2025

Through 18z Monday....VFR conditons will, by and large,  prevail
through the 18z TAF cycle. A few clouds, mainly diurnally driven,
will take place for the TAF sites (BRO/HRL) near the coast. Mainly
SKC skies will continue for MFE with strong mid-upper ridging
overhead.

Winds will continue out of the south-southeast 5-15 kts through the
forecast period. This afternoon into this evening there could be
gusts as high as 20 kts, courtesy of increased mixing heights and
some brief thermal and sfc pressure gradients.

&&

.MARINE...
Issued at 100 PM CDT Sun Aug 3 2025

Generally favorable marine conditions will prevail with low
to moderate seas and light to moderate south-southeasterly winds.
There will be low chances of showers and thunderstorms over the
Gulf Waters, especially offshore at times this week.

&&

.CLIMATE...
Issued at 1040 PM CDT Sat Aug 2 2025

Yesterday, Saturday August 2nd, all three climate sites set new
record highs. Brownsville broke a 123-year daily record high
yesterday with a high of 101 degrees (previously 100 degrees in
1902). Valley International in Harlingen set a new record high of
102 degrees (previously 101 degrees in 1953), and McAllen set of
new record high of 105 degrees (previously 104 degrees in 2009).
Additional records may be approached or broken Sunday and Monday.

Sunday, August 3rd Record High Temperatures
Brownsville: 102F in 1915
Harlingen: 102F in 2023
McAllen: 105F in 2022

Monday, August 4th Record High Temperatures
Brownsville: 101F in 2023
Harlingen: 102F in 2023
McAllen: 105F in 2023

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             80  97  79  95 /  10  10  10  30
HARLINGEN               76 100  75  97 /  10  10   0  30
MCALLEN                 79 103  79 100 /  20  10   0  20
RIO GRANDE CITY         77 105  78 101 /  20   0   0  10
SOUTH PADRE ISLAND      81  89  81  88 /  10   0  10  30
BAYVIEW/PORT ISABEL     78  94  78  93 /  10   0   0  30

&&

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

$$

SHORT TERM...23-Evbuoma
LONG TERM....23-Evbuoma
AVIATION...23-Evbuoma