492
FXUS64 KBRO 280434
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1034 PM CST Thu Nov 27 2025

...New KEY MESSAGES, DISCUSSION, AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1015 PM CST Thu Nov 27 2025

* Breezy southeasterly winds 15-25 mph with higher gusts Friday
  through Saturday.

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

* Big changes to the weather pattern as 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 and persist through at least Sunday in response to an
  enhanced pressure gradient and a strong cold front.

* Rain chances increase inland Saturday night through Monday and
  again Wednesday night through Thursday night. Greatest chances
  Sunday through Sunday night. Rain chances nearly everyday
  through next week for the Gulf Waters.

&&

.DISCUSSION...
Issued at 1015 PM CST Thu Nov 27 2025

The main weather headline during the forecast period will continue
to 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 Saturday, mainly rain-free weather is expected as a
1030-1040 mb sfc high pressure centered over the Midwest maintains
its influence over much of the country including Deep South Texas.
Light east-northeast winds tonight are expected to shift out of the
southeast on Friday as the aforementioned sfc high continues to
translate towards the eastern CONUS. A tightening pressure gradient,
courtesy of a developing low pressure system over the central
Rockies and the departing yet still strong sfc high pressure system
will result in a breezy day on Friday and Saturday with southeast
winds 15-25 mph gusting up to 30 mph or so. The strongest of winds
are expected to be over the open Gulf Waters where southeast winds
will have speeds between 20-25 kts or so. As a result of these
strong winds, a Small Craft Advisory has been issued for the
Laguna Madre and the Gulf Waters from Friday afternoon to Saturday
evening. Aided by the breezy southerly winds, a warm front will
lift over the region on Friday. Temperatures on Friday will be
similar to Saturday with highs mainly in the 70s and a few 80s
over parts of the Rio Grande Valley. Additional warm air advection
(WAA) on southerly winds will result in a warm spike on Saturday
with high temperatures topping out in the mid 80s for much of Deep
South Texas.

The warmup however will be brief as there is a strong 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
continue to advertise a highly amplified and active 500mb pattern
featuring a mild West U.S. vs. a Cold Central and East U.S. (PV lobe
tilted on the North America side) 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 an emerging 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 America 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 seen so far (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, some
15F degrees or so cooler than Saturday night, and some 10F degrees
cooler than normal. 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 continued
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 Monday and Tuesday nights
holding in the 40s most places (50s along the immediate coast),
which again will be well below normal levels.

Rain showers (some perhaps stratiform type) are possible Saturday
night through Monday in response and connection to the cold
frontal boundary. Currently, we have low to medium (20-60%) PoPs
over Deep South Texas during this time period with the best
chances being near the coast. Sunday- Sunday night is where we
expect the most widespread coverage. Additionally, we have
categorical PoPs along and east of IH-69C Sunday-Sunday night.
Even greater chances will take place over the open Gulf Waters
during this time. Rain showers are also possible over the Gulf
Waters Friday night and Saturday in connection to the aforementioned
warm front and again Monday night of next week. Hazardous
coastal/marine conditions are still expected to develop Friday
afternoon into the weekend in response to this strong cold front
and enhanced pressure gradient (see MARINE SECTION for more
details).

Wednesday will feature a slight warming trend as a return flow
develops out of the southeast resulting in increase warm air
advection (WAA). However, despite the slight warmup, another bout of
unsettled weather will develop over the forecast area as a nearby
shortwave trough/developing low pressure system will increase the
threat for showers and thunderstorms Wednesday night through
Thursday night. Currently, we have low to medium (20-40%) chances
across Deep South Texas with the higher chances located near the
coast. The combination of rain chances and increased cloud coverage
will limit warming potential Wednesday through Thursday. That said,
high temperatures Wednesday and Thursday are progged to reach the
70s across much of Deep South Texas to lower 80s along the RGV
(closer to normal levels). Overnight lows Wednesday and Thursday
nights will be in the 50s and 60s.

Thursday night into Friday, another cold front could be approaching
the area. This will result in warming remaining limited as high
temperatures on Friday will be similar to that of Wednesday and
Thursday (mostly 70s and lower 80s along the RGV). Overnight low
temperatures Friday night are expected to be in the 50s most places.

&&

.AVIATION...
(06Z TAFS)
Issued at 1015 PM CST Thu Nov 27 2025

Through 06z Saturday....VFR conditions are expected to prevail
through the 06z TAF cycle under an abundance of cloud cover. There
could be a time or two of MVFR ceilings.

Northeast winds will continue tonight with speeds between 5-10 kts.
On Friday, winds are expected to shift out of the southeast with
speeds between 10-15 kts and gusts between 25-30 kts.

&&

.MARINE...
Issued at 1015 PM CST Thu Nov 27 2025

Adverse (i.e. Small Craft Exercise Caution) conditions will continue
through tonight in the wake of the first fropa. An enhanced pressure
gradient driven by a developing low pressure system over the central
Rockies and a departing sfc high pressure system will result in breezy
southerly winds developing Friday through Saturday. As a result, a
Small Craft Advisory is in place for the Laguna Madre and the Gulf
Waters Friday afternoon through Saturday evening. A second, stronger
cold front will sweep through the region Saturday night into Sunday.
This will result in continued hazardous or dangerous marine conditions
to persist and a Small Craft Advisory may need to be extended into
at least Sunday. Marine conditions could improve by Tuesday night with
low to moderate winds and seas prevailing through next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             79  67  78  70 /   0  10  20  10
HARLINGEN               79  62  78  67 /   0  10  10  10
MCALLEN                 79  66  79  69 /  10   0  10  10
RIO GRANDE CITY         76  63  78  66 /  10  10  20  10
SOUTH PADRE ISLAND      76  71  77  73 /   0  10  20  10
BAYVIEW/PORT ISABEL     79  66  78  68 /   0  10  20  10

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory from noon Friday to 6 PM CST Saturday for
     GMZ130-132-135-150-155-170-175.

&&

$$

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