449
FXUS65 KBOU 172310
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
410 PM MST Wed Dec 17 2025

.KEY MESSAGES...

- Strong downslope winds impacting foothills and I-25 corridor
  will end this evening. Widespread wind gusts of 60-80 mph and
  localized gusts up to 90 mph are possible. A cold front will
  bring northwest winds gusting 50-60 mph across the northern
  plains this evening.

- Strong winds will continue to impact the mountains this evening
  through tomorrow morning, with gusts up to 80-90 mph expected at
  times.

- Banded snowfall and strong winds will lead to treacherous travel
  conditions in the mountains this afternoon and evening.

- Strong winds and periods of high fire danger will return Friday,
  with questions remaining regarding the spatial extent of the
  strongest winds.

- Mountain snowfall looks to return for Saturday.

&&

.DISCUSSION /Through Wednesday/...
Issued at 350 PM MST Wed Dec 17 2025

Winds are currently peaking across the Front Range and lower
foothills, with multiple reports of 80+ mph wind gusts. Hi-res
guidance continues to indicate strong winds continuing for the
next couple of hours for the lower elevations before backing up
into the mountains again this evening. We are still on track to
let the High Wind Warning expire for the lower foothills this
evening, and let the High Wind Warning for the mountains to
continue through tomorrow morning. While there will be brief lulls
in strong winds along the mountains overnight, generally expect
gusts up to 80 mph at times, with a gradual weakening through
Thursday late morning/early afternoon.

For the plains, gusty winds will continue through early this evening.
Then, a cold front is progged to enter the northern plains by 6/7
PM and quickly sweep south. QG fields show deep subsidence over
the plains, which will likely help bring down strong winds to the
surface. Gusts up to 60 mph are possible, particularly off the
Cheyenne Ridge. However, short-range guidance has continued to
indicate the strong winds reaching all the way down to Washington
county, so have included them in the warning. After midnight,
northwest winds weaken below high wind criteria. However, expect
gusty winds up to 40-50 mph to continue through the morning hours
Thursday.

Critical fire weather concerns are expected to continue this
afternoon despite marginal relative humidity values. Strong winds
along the foothills and adjacent plains will promote rapid fire
spread, should a fire occur. However, as winds weaken this evening
along the foothills, conditions will improve to let the Red Flag
Warning expire. In addition, even with the strong winds expected
with the cold front, slightly higher relative humidity values and
cooler temperatures will keep fire weather concerns at bay.

The Winter Weather Advisory will continue through tonight. Current
radar imagery shows snow showers ongoing for the northern mountains,
with minimal accumulations so far. However, with guidance indicating
strengthening frontogenesis across the higher terrain, banded snow
is possible, with snowfall rates reaching 1"/hr to briefly 2"/hr.
Total snow accumulations of 3-8" is still on track, with localized
higher amounts of 10" possible near ridgetops. Strong winds will
cause blowing snow along high passes, which will greatly reduce
visiblities.

Now for tomorrow. In general, cool temperatures and gusty winds are
expected for the entire forecast area. However, the primary
concern for strong winds will be across the northeastern plains in
the morning. The core of the upper level jet streak is still
progged to be overhead Thursday morning, with the 700-mb flow
reaching up to 70-80 kts. Modeled soundings indicate steep lapse
rates at the same time, which will help mix strong winds down to
the surface. In addition, hi-res guidance has continued to show
gusts reaching, or barely exceeding, high wind criteria. For this
reason, have opted to upgrade Sedgwick and Phillips counties to a
High Wind Warning tomorrow, with gusts up to 55-65 mph possible.
Elevated to critical fire weather conditions are possible,
particularly over the eastern plains (see Fire Weather
Discussion).

Another mountain wave and high wind event is expected along the
front range and foothills late Thursday into Friday. Models are
showing cross barrier flow around 70 to 100kts at ridge top. There
is a robust pressure gradient shown in the Sangster, with MSL
differences around 13 to 14mb between GJT and DEN. Models are
hinting at a weak inversion around 600mb in the afternoon and
showing some inverse shear in mid levels (80kts to ~50kts higher
up). The relatively weak nature of these ingredients lower
confidence a bit in the winds making it down towards the I-25
corridor. But, as we saw with the current event, this can definitely
change as we get closer to the event. Right now, we have very high
confidence in strong winds impacting the higher elevations of the
front range, with lowering confidence of really strong winds the
further east we go. A High Wind Watch will be in effect late
Thursday through late Friday for the mountains and Friday afternoon
for zones 38 and 39. The strong winds and dry conditions will lead
to fire weather concerns as well (see Fire Weather Discussion).

Weak QG subsidence Friday afternoon will transition to weak ascent
in the evening as the left exit region of the upper level jet
approaches. The approach of the jet will help bring an end to the
high wind event and trigger some snow showers in the mountains. The
best chance for snow this weekend will be overnight Friday into
early Saturday afternoon, with lower chances (036.

High Wind Watch from Thursday evening through Friday afternoon
for COZ033>036.

Red Flag Warning until 6 PM MST this evening for COZ238>243-245-
246.

High Wind Warning until 7 PM MST this evening for COZ038-039.

Fire Weather Watch from Friday morning through Friday evening
for COZ238>240.

High Wind Watch from Friday morning through Friday afternoon for
COZ038-039.

High Wind Warning until midnight MST tonight for COZ042-044-048-
049.

High Wind Warning from 5 AM to noon MST Thursday for COZ050-051.

&&

$$

DISCUSSION...MAI/AP
AVIATION...Danielson
FIRE WEATHER...MAI/AP

NWS BOU Office Area Forecast Discussion