303
FXUS64 KBRO 011738
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1238 PM CDT Thu Oct 1 2026

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

.KEY MESSAGES...
Updated at 1212 PM CDT Thu Oct 1 2026

 - Widespread Major (level 3 of 4) to Extreme (level 4 of 4) Heat
   Risk expected across the region today.

 - Cooler and wetter conditions are expected tonight into early
   next week due to a frontal passage and a multi-day rainfall
   event.

 - The Weather Prediction Center (WPC) has Deep South Texas under
   a Slight (level 2 of 4) to Moderate (level 3 of 4) Risk for
   flooding rainfall through tonight, a Marginal (level 1 of 4) to
   Slight Risk on Friday, and a Marginal Risk along the coast
   Saturday into Tuesday.

&&

.DISCUSSION...
Issued at 1212 PM CDT Thu Oct 1 2026

There remains a Major to Extreme risk of heat-related illness
today across most of the Rio Grande Valley. A Special Weather
Statement is in effect.

The weather pattern begins to change and turn unsettled today,
with increasing rain chances through the weekend, continuing
through the forecast period. An upper level trough, slow-moving
surface frontal boundary, and deep tropical moisture continue to
work east into this weekend and combine with humid southeasterly
flow off the Gulf to bring mostly beneficial rainfall into next
week.

The best chance of heavy rainfall into Saturday remains across
Zapata, Jim Hogg, Starr, Brooks, and Hidalgo counties, generally
working eastward through the Rio Grande Valley and lower Texas
coast with the front by late this weekend. A coastal trough and
surface low set up along the lower Texas coast by the end of the
weekend, continuing rain chances through most of the week and now
increasing the threat of heavy rainfall across the lower valley
Sunday into Tuesday.

Areas of advanced drought conditions may experience excessive
runoff and flash flooding where any heavy rain persists,
especially across the brush country, where flash flooding is more
common. The Weather Prediction Center has issued a Moderate Risk
(at least 40 percent chance) of flooding rainfall across Zapata,
Jim Hogg, Starr, western Brooks, and western Hidalgo counties
today through tonight, with a Slight Risk (at least 15-25 percent
chance) of flooding rainfall across the remainder of Brooks,
Hidalgo, most of Kenedy, western Willacy, and western Cameron
counties. The chance of flooding rainfall continues Friday into
Saturday across all of Deep South Texas and along the coast
Saturday into Tuesday.

The most likely rainfall amounts from today into early Sunday
morning are 2 to 4 inches across all Deep South Texas and the Rio
Grande Valley, with an additional 2 to 4 inches of rainfall
expected Sunday into Tuesday, mainly along the lower valley and
lower Texas coast.

Locally higher amounts are possible where any heavier rainfall
persists, with the latest probabilistic guidance of higher end or
reasonable worst case (10 percent chance) 48-HR rainfall amounts
of 5-8 inches across Zapata County into Saturday morning, and
generally 4-6 inches across the remainder of Deep South Texas and
the Rio Grande Valley into Sunday morning. Higher end or
reasonable worst case (10 percent chance) 48-HR rainfall amounts
of 3-6 inches are possible along the lower Texas coast and lower
valley from Sunday into Tuesday.

Expect another breezy afternoon today. The increased chance of
rain and cloud cover, as well as a northerly wind shift by the
weekend into early next week, will bring a taste of Fall and
welcomed break to the heat, with below normal temperatures
Saturday into early next week. Will continue to monitor beach and
marine hazards over the weekend, with a potential for tidal run-up
near high tides beginning Friday night and an elevated risk of
life-threatening rip currents.

&&

.AVIATION...
(18Z TAFS)
Issued at 1212 PM CDT Thu Oct 1 2026

VFR conditions are generally expected to prevail through the TAF
period, with MVFR ceilings and periodic showers possible Friday
morning streaming northwest from the Gulf towards BRO and HRL.
Gusty southeasterly winds diminish into this evening and remain
generally light through the remainder of the forecast period.

&&

.MARINE...
Issued at 1212 PM CDT Thu Oct 1 2026

An upper level low and slow-moving frontal boundary work through
Texas and approach coastal waters into this weekend before a
coastal trough of low pressure develops into mid next week. Expect
seas to build into this evening with SCEC to borderline SCA
conditions, with conditions improving into the weekend. Light to
moderate northerly winds are expected behind the frontal boundary
Saturday into late Sunday with Fall-like conditions and periods of
heavy rainfall and reduced visibility becoming more frequent into
Sunday night and through Monday. Marine conditions may
deteriorate again Monday and Tuesday due to the surface low and
coastal trough with SCEC to borderline SCA conditions.

&&

.HYDROLOGY...
Issued at 1212 PM CDT Thu Oct 1 2026

There is an increased threat of heavy rainfall along the Rio
Grande into this weekend which will lead to a rise in water levels
along the Rio Grande, Main Floodway, North Floodway, and Arroyo
Colorado into next week. The Falcon Reservoir remains very low and
has plenty of room to hold any increased flow along the Rio
Grande. For any interests stationed or positioned within levees
downstream of Falcon, including along the floodways and Arroyo
Colorado, through Starr, Hidalgo, and Cameron counties, please
continue to monitor river forecasts and water levels into next
week. Areas that have been dry for months may become inundated by
the weekend or early next week with flowing water.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             80  94  77  91 /  50  60  80  90
HARLINGEN               77  95  72  92 /  60  60  80  90
MCALLEN                 79  94  77  92 /  70  70  90  90
RIO GRANDE CITY         76  90  73  88 /  90  70  90  80
SOUTH PADRE ISLAND      82  88  80  86 /  40  50  80  90
BAYVIEW/PORT ISABEL     79  92  76  90 /  40  50  80  90

&&

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

$$

SHORT TERM...56-Hallman
LONG TERM....56-Hallman
AVIATION...56-Hallman