071
FXUS65 KBOU 042237
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
337 PM MST Thu Dec 4 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 /18Z TAFS through 18Z Friday/...
Issued at 1036 AM MST Thu Dec 4 2025

VFR to prevail through tonight and Friday. Southerly winds at DEN
and APA will weaken and become light and variable 19-21Z. Winds
then return to a southerly drainage direction after 00Z Friday. At
BJC and areas along the foothills, gusty west winds to 30 knots
are expected to develop around 00Z and continue through the night.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from midnight tonight to 11 PM MST
Friday for COZ031.

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

&&

$$

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