806
FXUS65 KBOU 051146
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
446 AM MST Fri Dec 5 2025

.KEY MESSAGES...

- Heavy, wind driven snow event likely (>80% chance) for the
  mountains Friday night through Saturday night, with difficult
  travel conditions.

- Stronger winds at times into early next week.

- Milder temperatures ahead, with above normal temperatures by
  early next week.

&&

.SHORT TERM /Through Friday/...
Issued at 216 PM MST Thu Dec 4 2025

Water vapor satellite imagery showing increasing moisture heading
towards northern Colorado as a shortwave in the northwest flow aloft
nears Colorado. This will bring snow back to the northern mountains
for tonight and Friday. Cross sections show the moist layer being
somewhat shallow, from the surface to roughly 600mb. This will keep
snowfall amounts on the light side across the northern mountains.
Just enough snow however for a Winter Weather Advisory for Western
Grand and Western Jackson Counties where 4 to 8 inches of snow will
be possible tonight and Friday. For the rest of the mountains, up to
5 inches will be possible.

For areas east of the Continental Divide, lower surface pressure
will bring increasing west to northwest winds to the Front Range
mountains and foothills. Some of these gusty winds may spread east
of the foothills. Localized blowing snow will be possible, but
widespread impacts are not expected. Temperatures are expected to
run near to slightly below normal tonight and Friday with highs in
the upper 30s to lower 40s across northeast Colorado. Can`t rule out
a little light rain/snow over the far northeast plains as the
shortwave moves across the region. Any precipitation will be very
light.

&&

.LONG TERM /Friday night through Thursday/...
Issued at 216 PM MST Thu Dec 4 2025

Main story of the long term period is the potentially significant
snow/wind event across the mountains this weekend.

While snow will be ongoing to start the forecast period, cross-
sections are fairly meager with the depth of moisture embedded in
the west-northwesterly flow aloft. That will be short lived, as a
another shortwave races towards the mountains late Friday night
into Saturday. Model cross-sections show well-aligned WNWerly flow
with moisture deepening to around 400mb by Saturday morning. As a
result, orographic snow should quickly pick up across the
mountains, with periods of moderate to heavy snow likely through
most of the day Saturday. Considerable blowing snow is also
expected, with 30-50kt boundary layer flow likely leading to at
least a few gusts of 50-60 mph across favored terrain features.
While gusty winds may reduce snow ratios a bit during the period
of heavy snow, the combination of snow and wind is expected to
lead to widespread travel issues across a majority of our mountain
passes. We went with an upgrade to a Winter Storm Warning, and
also tweaked the timing a bit to emphasize the period of highest
impact across the I-70 corridor. It`s possible some impacts extend
into Sunday, but a majority of the accumulating snow should fall
before midnight Saturday night.

Meanwhile, most of the lower elevations should be fairly dry with
a modest warming trend over the weekend. There may be a few light
rain or snow showers on Saturday as the shortwave passes, but
guidance is far from enthusiastic about precipitation chances for
most of the I-25 corridor. Highs on Saturday should reach the mid
to upper 40s, with low to mid 40s on Sunday.

As we enter next week, guidance is in reasonably good agreement
with the upper level pattern, as northwest flow continues to
prevail across the western CONUS. There will likely be a few
periods of snow across the mountains during the week as a few
shortwaves pass near the region. There may also be a period of
stronger wind gusts on Tuesday or Tuesday night following the
passage of a stronger shortwave to the north. Forecast confidence
decreases quite a bit by the latter half of next week, though some
deterministic guidance tries to bring much warmer weather to the
Denver metro and plains closer to next weekend.

&&

.AVIATION /12Z TAFS through 12Z Saturday/...
Issued at 418 AM MST Fri Dec 5 2025

VFR conditions expected throughout the TAF period. Winds at DEN
and APA will vary between southeast and southwest this morning but
the speeds will be light. At BJC, there will be periodic westerly
gusts up to 30 knots possible but most of the time will be spent
with light and variable winds.

BJC will see sporadic westerly gusts throughout the day today
with the highest likelihood of westerly gusts in the afternoon.
DEN and APA may see either light northeast winds or west-
northwesterly winds with gusts up to 15 knots. The northeast winds
are more likely so the TAF was adjusted to include that.

Moderate to strong drainage flow will develop Friday night. Winds
will shift to the northwest on Saturday with strong gusts up to 40
knots possible in the afternoon.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 PM MST this evening for COZ031.

Winter Storm Warning from 11 PM this evening to 11 PM MST
Saturday for COZ031-033-034.

&&

$$

SHORT TERM...12
LONG TERM....Hiris
AVIATION...Danielson

NWS BOU Office Area Forecast Discussion