545
FXUS65 KBOU 280317
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
817 PM MST Sat Dec 27 2025

.KEY MESSAGES...

- A cold front will bring below freezing temperatures to the
  forecast area Sunday morning.

- 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.

- Drying trend continues for the I-25 corridor. In general
  snowfall amounts of less than an inch are expected, with a
  couple of bands potentially producing 1-2".


&&

.UPDATE...
Issued at 803 PM MST Sat Dec 27 2025

Primary band of snow over the mountains, associated with the mid-
level frontogenesis, has slowly sunk south into the I-70 corridor
over the past few hours. Snow rates in the band are still fairly
impressive, where snow stakes at Eldora and Winter Park have
picked up a few inches of snow in about 2 hours. The current
winter highlights in the mountains have not changed.

Meanwhile, it`s hard to ignore the persistent dry signal across
most of today`s CAMs - and the 00z guidance has not been a source
for any optimism. While the HRRR is likely too dry - surface dew
points behind the front have been 3-5F more moist than 1hr
forecasts - even the more aggressive guidance only paints ~0.10"
of QPF anywhere in the urban corridor. There`s still a narrow
window where shallow upslope and a favorable jet axis overlap, but
in general it looks like it`ll be hard to get more than an inch
of snow in most of the metro. If a persistent band of snow can
develop at some point, there may be some localized totals of 1-3".
As a result, we`ve cut back on QPF/SnowAmt for most locations
east of the continental divide.

&&

.DISCUSSION /Through Saturday/...
Issued at 255 PM MST Sat Dec 27 2025

Current water vapor imagery shows a stream of Pacific moisture
moving into the high country, with snow showers ongoing in the Park
Range and northern Front Range mountains. We expect snow to become
more widespread this afternoon/evening as favorable orographics
ahead of an approaching shortwave trough will promote light to
moderate snowfall through tomorrow morning. Short and long range
guidance still favor strong frontogenesis later today and overnight,
which will create snowbands and promote localized heavy snowfall at
times, particularly in the Park Range. Areas of blowing snow will be
a concern, especially across high passes as winds could gust up
to 50 mph. With reduced visiblities and slick roads, expect
difficult to hazardous travel this evening through Sunday
morning. Still think total accumulations will range between 8-18"
in the Park and northern Gore Range and 4-12" along the Front
Range, with highest accumulations north of I-70.

For the plains, the trend is not our friend unfortunately as
expected snowfall amounts have decreased in the last 24 hours. A
strong cold front is progged to enter our forecast area this evening
and tonight, bringing gusty north/northeasterly winds and colder
temperatures. Ahead of this front, light rain and rain/snow mix will
occur before the cold air overcomes warm temperatures and allow
light snowfall. Most short range guidance have all trended towards
a slightly warmer and drier airmass at the lower levels, with
total snowfall accumulations between trace to a couple tenths, and
best area for snowfall across the Palmer Divide. However, long
range guidance has held relatively steady in areas along the lower
foothills/plains receiving a couple of inches by Sunday. Most
likely, the northern and eastern plains will receive a dusting to
an inch of snow by late Sunday morning. Due to favorable upsloping
and frontogenetical forcing, the Denver metro, western urban
corridor, and Palmer Divide could see slightly more
accumulations. Lastly, any banded snowfall will create localized
higher amounts (up to 2-3"). As temperatures are expected to dip
below freezing tonight and Sunday morning, expect slick roads
wherever precipitation falls.

Snow will gradually end late Sunday morning. Temperatures will stay
below freezing throughout the day, with low 30s as expected highs
across the plains, and single digits to mid teens for the high
country.

Quieter conditions are expected Monday and through the rest of the
week. Ensemble guidance has continued to indicate Colorado on the
eastern edge of an upper level ridge with a surface high pressure
settling over the western United States. With weak northwest flow
aloft, dry and warming conditions will prevail. Monday and Tuesday
will see near seasonal temperatures, with highs in the 40s both days
across the plains. Then, as the axis of the upper level ridge shifts
over Colorado towards the later half of the week, temperatures
should warm up to the mid-to-high 50s. Despite dry conditions
allowing relative humidity values to drop to 20% almost each day,
recent precipitation and relatively light winds should keep fire
weather concerns at bay. However, can`t rule out localized elevated
fire weather conditions, particularly in areas that don`t receive
precipitation.

Our next chance of precipitation comes towards the end of the
week/weekend, as ensemble solutions show an upper level trough
trekking over northern Colorado. As of right now, the bulk of the
precipitation is expected to be confined to the high country.
However, will continue to monitor for any changes.

&&

.AVIATION /00Z TAFS through 00Z Monday/...
Issued at 431 PM MST Sat Dec 27 2025

Cold front still expected to arrive close to 06z tonight, with
some stratus filling in behind the front. Recent trends are drier
across the metro tonight into Sunday AM but there should be a mix
of SCT/BKN 020-040 along with a few bands of light snow. There
could be periods of MVFR or IFR conditions through about 15z
before a gradual clearing is anticipated. Gusty NNE winds are
expected with the cold front initially, with some sort of
northerly component continuing through the day Sunday.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 5 AM MST Sunday for COZ031.

Winter Weather Advisory until 11 AM MST Sunday for COZ033-034.

&&

$$

UPDATE...Hiris
DISCUSSION...MAI
AVIATION...Hiris

NWS BOU Office Area Forecast Discussion