588
FXUS64 KBRO 271121 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
521 AM CST Thu Nov 27 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 515 AM CST Thu Nov 27 2025

* Increasingly tranquil and mainly rain-free weather conditions with
  seasonable level temperatures are expected Thanksgiving Day and
  Black Friday with highs mostly in the 70s.

* A brief warm spike takes place on Saturday with highs in the 80s.

* A strong cold front Saturday night into Sunday will bring a
  notably cooler airmass (potentially the coldest since last
  February) to the region Sunday through early next week.

* Dangerous surf and boating conditions are expected to return
  Friday night and persist through at least Sunday in response to
  the strong cold front.

&&

.DISCUSSION...
Issued at 1100 PM CST Wed Nov 26 2025

The main weather headline during the forecast period will focus
on a strong cold front (Arctic origins) that will bring the
coldest airmass of the season (since last February) to all of Deep
South Texas and the Rio Grande Valley Saturday night/Sunday
through next Tuesday night (~November 29/30-December 3 timeframe).

Tonight through Friday, dry, increasing tranquil, and mainly rain-
free weather conditions will take place amid a 1030-1040 mb sfc
high pressure system centered over the central and northern Plains
and Midwest. Temperatures will remain cooler than prior days, but
will still remain slight warmer than normal levels with highs
topping out in the 70s most places (80s along the RGV) and
overnight lows in the 50s and 60s.

Friday night through Saturday, a warm front associated with a
developing mid-latitude cyclone over the central Rockies will result
in a warming trend taking place. Overnight lows Friday night are
progged to be in the 60s most places with some 70s along the RGV. On
Saturday, this warm front will result in high temperatures climbing
into the 80s across all of Deep South Texas. The warmup however will
be brief as there is a growing consensus amongst global forecast
models and ensembles that a major large-scale weather pattern shift
will take place over the weekend into the early parts of next week.
Numerous weather models/ensembles are advertising a highly amplified
and active 500mb pattern featuring a mild West U.S. vs. a Cold
Central and East U.S. developing late this week into the early parts
of next week (~November 30-December 3 timeframe).

While this will bring plenty of wintry weather across the northern
tier states, a strong cold front associated with the aforementioned
mid-latitude cyclone (low pressure system) over the central Rockies
will sweep through the state of Texas on Saturday. There still
remains some discrepancies amongst forecast guidances on the precise
timing of the cold fropa, which would impact high temperatures on
Sunday. Typically, these cold shallow airmasses tend to have a faster
timing than than what most global forecast models suggest. The hi-
res, CAM North American Model (NAM) captures these trends better.

That said, it appears that sometime Saturday night into Sunday, this
strong cold front with Arctic origins will sweep through all of Deep
South Texas and the Rio Grande Valley. In it`s wake will be the
coldest airmass of the season (since last February). High temperatures
on Sunday will likely be reached early in the day as temperatures
are expected to fall through the day. High temperatures from Saturday
to Sunday will be about 10F degrees cooler, but closer to seasonable
norms with values on Sunday in the low to mid 70s along the RGV and
60s over the Northern Ranchlands.

Clearing skies amid additional cold and dry air advection will
result in a markedly chilly Sunday night as overnight low
temperatures are expected to plunge into the 40s most places and
50s along the mid to lower valley and towards South Padre Island
(again some 10F degrees cooler than Saturday night). A full cold
and dry air advection regime will be in place by Monday. This
combined with a modified 1020-1025 mb sfc Arctic high pressure
system over the region will result in cooler than normal
temperatures with high temperatures failing to make it out of the
60s on both Monday and Tuesday. On Monday, highs could struggle to
make it out of the 50s over the Northern Ranchlands. Clear skies
and additional radiational cooling will result in overnight low
temperatures holding in the 40s most places (50s along the
immediate coast), which will be well below normal levels.

Stratiform rain showers are possible Saturday night through Monday
night in response and connection to the cold frontal boundary.
Currently, we have low to medium (20-50%) PoPs over Deep South
Texas during this time period with the best chances being near the
coast. Categorical PoPs are in place over the Gulf Waters during
this time period. Rain showers are also possible over the Gulf
Waters Friday night and Saturday in connection to the aforementioned
warm front and again Tuesday through Thursday of next week.
Hazardous coastal/marine conditions are expected to develop Friday
night into the weekend in response to this strong cold front (see
MARINE SECTION for more details).

Wednesday will make the onset of a warming trend as a return flow
develops out of the southeast resulting in increase warm air
advection. High temperatures on southerly winds will climb back
into the 70s across much of Deep South Texas (closer to normal
levels). By Thursday, additional warm air advection will result in
high temperatures climbing into the 80s most places. Overnight
lows Wednesday and Thursday nights will be in the 50s and 60s.

&&

.AVIATION...
(12Z TAFS)
Issued at 515 AM CST Thu Nov 27 2025

VFR TAFs are expected to persist through the TAF period at all TAF
sites. Generally northeasterly winds are expected for the period.
While winds should be light for the morning hours, gusty winds
around 20 knots are expected for the afternoon hours. These winds
should weaken later this evening.

&&

.MARINE...
Issued at 1100 PM CST Wed Nov 26 2025

Adverse (i.e. Small Craft Exercise Caution) conditions will continue
tonight through Friday in the wake of the first fropa. On the heels
of the first fropa and still adverse marine conditons, a second,
stronger cold front will sweep through the region Saturday night
into Sunday. Ahead of this front, hazardous or dangerous marine
conditions will develop Friday night into Saturday with Small Craft
Advisory (SCA) conditions being likely. These conditions are likely
to continue through at least Sunday before potentially improving early
next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             79  67  79  70 /   0   0  20  10
HARLINGEN               78  62  79  66 /   0   0  20  10
MCALLEN                 79  64  79  69 /   0   0  10  10
RIO GRANDE CITY         78  62  79  66 /   0  10  20  10
SOUTH PADRE ISLAND      77  72  77  73 /   0   0  20  20
BAYVIEW/PORT ISABEL     78  66  79  69 /   0   0  20  10

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk until 6 AM CST early this morning for
     TXZ451-454-455.

GM...None.
&&

$$

SHORT TERM...23
LONG TERM....23
AVIATION...64-Katz