627
FXUS64 KBRO 301120 AAA
AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
520 AM CST Sun Nov 30 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 515 AM CST Sun Nov 30 2025

* Big changes to the weather pattern in store as a strong cold
  front tonight into Sunday will bring a notably cooler airmass
  (potentially the coldest since last February) to the region
  Sunday through early next week.

* Adverse to dangerous surf and boating conditions are expected to
  persist through at least Sunday in response to an enhanced
  pressure gradient and a strong cold front.

* Rain chances increase inland tonight through Monday (possibly
  lingering showers Monday night into Tuesday) and again
  Wednesday night through Friday night. Greatest chances Sunday
  through Sunday night. Rain chances nearly everyday through next
  week for the Gulf Waters.

&&

.DISCUSSION...
Issued at 1113 PM CST Sat Nov 29 2025

Big changes in the weather pattern are in the offing for all of Deep
South Texas and the Rio Grande Valley. Over the next 12 or so hours,
a strong southward advancing cold front (currently moving across
central Texas) will sweep across all of Deep South Texas and the Rio
Grande Valley. Associated with this cold front will be increased
rainfall chances and blustery conditions along with falling temperatures
throughout the day on Sunday.

Due to the timing of the cold fropa, the development of blustery
north winds 10-20 mph with higher gusts and increased cloud coverage
and rain chances, high temperatures will be reached during the
morning hours with values struggling to make it out of the 70s most
places (60s across parts of the Northern Ranchlands). Rain showers
and maybe a rumble or two of thunder will increase in coverage
during the morning hours on Sunday and persist through the day.
Currently, we have low to medium (20-50%) chances along and west
of IH-69E and categorical PoPs along and east of IH-69E. Due to
the front being progressive along with cold and dry air advecting
into the region, we expect mainly rain showers (stratiform type)
on Sunday. That said, we don not anticipate the risk for flash
flooding to occur though there could be areas of ponding.

Despite cloud coverage and maybe some rain showers lingering,
additional cold and dry air advection will result in a noticeably
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 remain in place on
Monday with some lingering rain showers. This combined with a
1020-1025 mb sfc high pressure system over the region will result
in continued cooler than normal temperatures with high
temperatures struggling to make it out of the 50s on Monday and
60s on Tuesday. 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 RGV and
immediate coast), which again will be well below normal levels.

Another bout of unsettled weather is expected to 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 Friday night. Currently, we have low to
medium (20-50%) chances across Deep South Texas with the higher
chances located near the coast.

Temperatures will gradually moderate through the week, however, the
combination of rain chances and increased cloud coverage will limit
warming potential. That said, high temperatures by Wednesday are
progged to reach the 70s across much of Deep South Texas. Highs
mainly in the 70s (lower 80s along the RGV) are then expected to
persist through next Sunday. Overnight lows Wednesday through
Saturday night will mainly be in the 50s. Given the explanation
above about model biases and after collaboration with neighboring
offices, have decided to use a blend of the NBM 25th percentile
and NAM12 through Tuesday.

&&

.AVIATION...
(12Z TAFS)
Issued at 515 AM CST Sun Nov 30 2025

The majority of the TAF period will see a mixture of MVFR to IFR
conditions as a cold front moves through the region bringing some
showers and thunderstorms to the region. The timing for the
showers have been based around the HRRR. Some gusty northerly
winds behind the front with those gusts around 20 to 25 knots.

&&

.MARINE...
Issued at 1113 PM CST Sat Nov 29 2025

Small Craft Exercise Caution (SCEC) conditions are expected
to persist through tonight. An enhanced pressure gradient from a
strong cold front will result in strong winds and increased seas on
Sunday. These hazardous marine conditions will persist into Monday
before showing some improvements. A Small Craft Advisory has been
issued from 6 AM CST Sunday to 6 AM CST Monday as a result.
Adverse to hazardous marine conditions are expected to persist
through Tuesday before becoming more favorable thereafter.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             74  49  58  54 /  70  60  40  30
HARLINGEN               71  47  56  49 /  60  50  30  20
MCALLEN                 71  49  58  52 /  30  40  20  20
RIO GRANDE CITY         66  47  60  50 /  20  40  20  10
SOUTH PADRE ISLAND      74  56  63  62 /  80  70  50  40
BAYVIEW/PORT ISABEL     74  49  59  53 /  70  60  40  30

&&

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

GM...Small Craft Advisory until 6 AM CST Monday for GMZ130-132-135-
     150-155-170-175.

&&

$$

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