581 
FXUS64 KBRO 261111 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
511 AM CST Wed Nov 26 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 509 AM CST Wed Nov 26 2025

* Dangerous surf and some tidal run-up at the beach expected
  Wednesday afternoon.

* Difficult boating conditions arrive Wednesday for Laguna Madre 
  and the Gulf, continuing over the Gulf into Wednesday night.

* Some welcome rain (showers and storms) late tonight and
  Wednesday along a front. Marginal (Level 1 of 5) Risk for severe
  thunderstorms tonight into Wednesday (large hail greatest 
  threat).

* Marginal (Level 1 of 4) Risk for Excessive rainfall tonight 
  into Wednesday across Deep South Texas. Heavy rain resulting in 
  localized nuisance flooding is possible.
 
* Stronger front could arrive early Sunday with much cooler 
  temperatures and dangerous surf/boating conditions returning.

&&

.DISCUSSION...
Issued at 1040 PM CST Tue Nov 25 2025

Drastic changes to the weather pattern that includes notably cooler 
temperatures, multiple coastal/marine hazards, and much needed 
rainfall in the form of showers and thunderstorms (some of which can 
be strong to severe) are expected to take place within the next 12 
hours across Deep South Texas and the Rio Grande Valley. 

The latest sfc MSAS analysis showed the well advertised frontal 
boundary draped over Brush Country (i.e. Starr, Jim Hogg, and Brooks 
County) this evening with a strong to severe thunderstorm cell 
tracking over northwestern Zapata into south-central Webb County. 

Tonight through Wednesday: Through tonight, expect for shower and 
thunderstorm coverage to increase across Deep South Texas and the 
Rio Grande Valley as the aforementioned frontal boundary continues 
to gradually work its way southward into northeastern Mexico. 
Despite some capping per the 00z BRO sounding and weak flow aloft, 
mixed-layer (MLCAPE) values up to 1,500 J/kg and 0-6km bulk shear 
values between 30-40 kts will support a conditional threat for 
severe thunderstorms through tonight and into Wednesday morning with 
the main threat being large hail. The Storm Prediction Center (SPC) 
has placed all of Deep South Texas under a Marginal (Level 1 of 5) 
Risk for severe thunderstorms through tonight and into Wednesday 
morning. Heavy rainfall and the risk for some ponding/nuisance 
flooding will also be a concern as these storms are slow movers with 
highly efficient rainfall rates. The combination of rainfall 
chances, increased cloud coverage, and the fropa will result in a 
notable airmass change on Wednesday. Despite returning to near 
seasonable levels, temperatures on Wednesday will be 10-20F 
degrees cooler than on Tuesday with projected highs in the 70s 
most places to lower 80s across Cameron County. 

An enhanced pressure gradient associated with the frontal boundary 
will result in strong northeast winds with speeds as high as 25 mph 
and higher gusts developing after daybreak on Wednesday. These winds 
will result in hazardous coastal/marine conditions on Wednesday (see 
MARINE SECTION). 

Wednesday night through Saturday night: By Wednesday evening/night, 
any lingering showers should have come to an end with winds also 
becoming lighter leaving behind a pleasantly cooler night.
Overnight low temps are progged to be in the 50s most locations 
to the 60s across Cameron County and areas along the coast. Dry, 
tranquil, and notably cooler weather will persist through Friday 
with highs in the 70s to lower 80s. Winds will shift out of the 
southeast on Friday marking the onset of warm air advection (WAA) 
into the region. That said, Saturday will feature highs returning 
into the 80s across the region. The warmer than normal 
temperatures will be brief, however, as another cold front 
approaches from the north Saturday-Saturday night. 

Saturday night through Wednesday: Saturday night into Sunday, 
forecast models are suggesting another cold front will sweep through 
Deep South Texas. Highs on Sunday will be near normal levels and 
notably cooler from Saturday. As cold air advection continues to 
build/increase over the region, some of the coldest air of the 
season is set to arrive Sunday night through Tuesday night. Sunday 
night, overnight lows are expected to fall into the 40s across the 
Ranchlands to the 50s along the Rio Grande Valley. Widespread 40s
are expected Monday and Tuesday nights. Highs in the 60s are 
expected to take place Monday and Tuesday. By Wednesday, east- 
southeast flow will potentially begins the process of warmer air 
advecting into the region. Stratiform rain showers associated with
the marine layer are also possible Saturday night through Tuesday
especially areas closer to the coast. 

&&

.AVIATION...
(12Z TAFS)
Issued at 509 AM CST Wed Nov 26 2025

The cold front is working south from the ranchlands into the Rio
Grande Valley this morning, with an increasing chance of showers
and isolated thunderstorms. By late morning, the chance of rain
diminishes and northeasterly winds increase, becoming breezy to
windy into the evening. MVFR ceilings may persist into the early
evening before improving from west to east tonight. 

&&

.MARINE...
Issued at 1040 PM CST Tue Nov 25 2025

Hazardous marine conditions are expected to develop on Wednesday 
in response to an enhanced pressure gradient associated with a 
passing frontal boundary. Small Craft Advisory (SCA) conditions 
are expected on Wednesday into Wednesday night over the Laguna 
Madre and Gulf Waters. Small Craft Exercise Caution (SCEC) 
conditons are expected thereafter (Wednesday night into Thursday).
Thursday night into Friday, marine conditions are expected to 
deteriorate once again with SCA conditions developing are early 
as Friday evening ahead of a second cold front. Hazardous marine 
conditions are expected to continue through Sunday. Marine 
conditions could then begin to improve Monday through Wednesday of
next week.

&&

.CLIMATE...
Issued at 1229 PM CST Tue Nov 25 2025

The record/near record heat of the past week has pushed nearly all
RGV locations into the top five warmest Novembers on record
through the 24th. Those rankings may rise a bit higher after today
(25th). With day/night averages only expected to drop close to the
long-term normals, if not a touch above, Wednesday through Friday
- and another 10 degree above average number for Saturday - we're
  locking in on another top-ten warmest finish for everyone when
  we count the numbers at the end of November. Sunday's now
  expected cool-down won't be enough to flip the script.

Here are the rankings, and departure from the top, for available
locations (with minimal missing data) through the 24th:

Brownsville (since 1878): 76.3 degrees, #2, -0.8 degrees from #1
McAllen (since 1941):  76.9 degrees, #2, -1.1 degrees from #1
Harlingen (since 1912): 73.2 degrees, #6, -1.2 degrees from #1
Weslaco (since 1914):  74.6 degrees, #3, -1.3 degrees from #1
RGC (since 1897)*: 73.9 degrees, #4, -2.9 degrees from #1

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             79  66  78  66 /  80  20  10   0 
HARLINGEN               78  59  78  61 /  70  10   0   0 
MCALLEN                 78  61  78  64 /  60  10   0   0 
RIO GRANDE CITY         76  56  76  61 /  60   0   0  10 
SOUTH PADRE ISLAND      79  72  76  71 /  80  20  10   0 
BAYVIEW/PORT ISABEL     79  65  78  66 /  70  10   0   0 

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk through late tonight for TXZ451-454-455.

     High Surf Advisory from 9 AM this morning to 8 PM CST this 
     evening for TXZ451-454-455.

GM...Small Craft Advisory until midnight CST tonight for GMZ130-132-
     135-150-155-170-175.

&&

$$

SHORT TERM...23-Evbuoma
LONG TERM....23-Evbuoma
AVIATION...56-Hallman