231
FXUS65 KBOU 271022
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
322 AM MST Sat Dec 27 2025

.KEY MESSAGES...

- Warm and dry across the plains today before a cold front brings
  colder temperatures for Sunday.

- Mountain snow continues into early Sunday morning. The heaviest
  snow will be in the Park and Gore Ranges where a Winter Storm
  Warning is in effect. Moderate amounts are expected across the
  Front Range mountains with a Winter Weather Advisory in effect.

- Uncertainty in the snow amounts for the lower elevations from
  tonight into Sunday morning. Anticipate T-2" of snow expected
  on the east side of the I-25 corridor and 2-5" on the west side
  of the I-25 corridor.

&&

.UPDATE...
Issued at 322 AM MST Sat Dec 27 2025

One more day of mild temperatures is expected across the plains
today with highs in the mid 50s to lower 60s. Meanwhile, snow is
expected in the mountains. Satellite imagery shows Pacific
moisture streaming across the northern portion of the state. The
Winter Storm Warning remains in effect for the Park Range
mountains through 5 am Sunday. Better moisture arrives later today
for the central mountains, so a Winter Weather Advisory is in
effect beginning at 11 am today for the Front Range Mountains and
continues through Sunday.

The biggest concern in the near term is the continued uncertainty
in snowfall amounts across the lower elevations later tonight and
into Sunday morning. A strong cold front is expected to move
south by midnight. While there is favorable frontogenesis, there
is a lot of dry air in the lower levels. This is a quick hitting
system and it may take some time for the atmosphere to saturate.
Precipitation could begin as liquid before changing over to snow
and that could lead to slick roads. However, latest models also
show meager snow amounts for areas near the Wyoming border. For
the Front Range Foothills and Mountains, snow amounts could be
higher, especially with the potential for banding.

Snow will come to an end by midday Sunday, but temperatures will
remain cold. And with clearing skies and lighter winds Sunday
night, overnight lows will be in the single digits and teens.


.DISCUSSION /Through Friday/...
Issued at 240 PM MST Fri Dec 26 2025

Water vapor imagery shows shortwave troughs over northern
California and northwest Washington state with a broader trough
over the western US. These shortwave troughs will combine and move
into Colorado Saturday night into Sunday. Ahead of this trough, a
stream of Pacific moisture will move into far northern Colorado
tonight. This will bring snow to the Park Range mountains and the
Winter Storm Warning begins at midnight tonight as a result. A lot
of that moisture will miss the Front Range Mountains tonight and
Saturday morning so PoPs and QPF amounts are on the lower side
there. It is not until around midday Saturday that better
moisture and orographic flow arrives in the Front Range Mountains
that snow will begin there. Therefore, a Winter Weather Advisory
was issued starting at 11AM. Strong frontogenesis ahead of the
shortwave trough will create bands of moderate to heavy snow in
the mountains Saturday afternoon through Saturday night. Travel
will be poor to hazardous especially Saturday night when the sun
sets and road temperatures decrease below freezing. Orographic
snow showers will continue through midday in the mountains before
coming to an end. Storm total snowfall amounts are expected to be
between 8-18 inches in the Park and Gore Ranges and 4-12" in the
Front Range.

Across the I-25 corridor and eastern plains, Saturday will be mild
with highs in the upper 50s to low 60s. A strong cold front at
the surface will move across the plains shortly before midnight
near the Wyoming border and around 2-4 AM near the Palmer Divide.
Behind the front, northeast winds will develop which will create
upslope flow. That low level forcing will combine with the upper
level forcing from the PVA ahead of the trough and the mid level
frontogenesis to create a couple brief bands of snow that will
spread across the area. The latest ensemble guidance has decreased
the QPF and snow amounts slightly. Roughly 0.10-0.15" QPF is
forecast on the east side of the I-25 corridor with between
0.15-0.30" on the west side of the I-25 corridor. The snow amount
forecast was decreased slightly for the eastern I-25 corridor with
1-3" now forecast. The western I-25 corridor is still expected to
receive 2-5" of snow. Across the eastern plains, 0-2" of snow is
forecast with the highest amounts around Akron to Last Chance.
Due to the uncertainty, no winter weather highlights were issued
at this time. However, highlights may be needed especially for the
Sunday morning travelers which are expected to encounter poor
road conditions.

Snow will end Sunday around midday with clearing skies. Single
digit to low teen lows are forecast across the plains.

Colorado will be on the eastern edge of a ridge aloft late Monday
through the rest of the work week. This will lead to dry
conditions with warming temperatures. Highs in the 50s are
forecast Tuesday through Friday across the plains. The next chance
for precipitation will be next weekend for our forecast area.

&&

.AVIATION /12Z TAFS through 12Z Sunday/...

VFR will persist through at least 06Z Sunday. Then areas of snow
are expected to develop with MVFR/local IFR. Winds have
transitioned to a fairly normal south/southwest and are expected
to hold through about 18Z Saturday. After that, more uncertainty
enters the picture. Most short range higher resolution models
bring a stronger westerly component to the TAF sites by 18Z, while
other guidance is later or remaining VRB. We think the cirrus
should be thin enough to allow for mixing, and thus we`ve opted to
go more westerly with gusts around 20-24 kts possible but
starting closer to 20Z at KDEN and KBJC. KAPA could see them as
early as 17-18Z, and they`ll also have a chance of gusts >25 kts.
Winds are then most likely to turn west/northwest by 00Z in
prefrontal mode, and eventually north/northeast post initial weak
front/surge by 03Z-04Z Sunday. A strong cold front will likely
arrive by 06Z, with lower ceilings and bands of snow behind it.
The MVFR/local IFR conditions are most likely between 06Z and 12Z
Sunday with improvement expected by 18Z.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from midnight tonight to 5 AM MST Sunday
for COZ031.

Winter Weather Advisory from 11 AM Saturday to 11 AM MST Sunday
for COZ033-034.

&&

$$

UPDATE...Stark
DISCUSSION...Danielson
AVIATION...Stark/Barjenbruch

NWS BOU Office Area Forecast Discussion