393
FXUS65 KBOU 032055
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
155 PM MST Sat Jan 3 2026

.KEY MESSAGES...

- Stronger downslope winds Sunday, combined with record/near
  record warmth and perpetual dryness, will lead to elevated to
  critical fire weather conditions for parts of the foothills and
  I-25 corridor.

- Next round of light to moderate mountain snow is still on track
  for Monday into Tuesday, favoring the northern mountains again.

- Lower elevations will remain dry and mild through Wednesday.

- Signs of colder and more unsettled weather returning for
  Thursday and Friday.

&&

.DISCUSSION /Through Saturday/...
Issued at 154 PM MST Sat Jan 3 2026

Model solutions for tonight and Sunday remain consistent, showing
potential for a weakly amplified mountain wave due to marginal
stability profile but strengthening mid level flow. The gradients
aren`t terrific per local Sangster output, but the mid level flow
and cross mountain component increases to around 40 kts late
tonight and Friday as the current upper level ridge axis shifts
eastward. Therefore, with the above ingredients, we expect the
bulk of the gusty mountain wave winds to hold in/immediately
adjacent to the foothills (aka Highway 93 Boulder- Golden), and
they shouldn`t have much success or persistence farther east. The
wind prone areas of the Front Range Mountains and Foothills should
still see a few gusts of 60-70 mph during the peak of the event
Sunday morning, with a slow retreat of those stronger winds into
the higher elevations of the Front Range as the forward shear
profile strengthens (weakening the mountain wave amplification).
See more regarding the resulting fire weather threat in the Fire
Weather Discussion section. Regarding temperatures, with a mild
start and then considerable sunshine behind the departing high
clouds of tonight, we`ll likely be approaching record warmth yet
again. Records for Sunday include 67 at Denver and Boulder, 68 in
Fort Collins, 69 at Akron, and 71 in Limon. Denver and Boulder
would have the greatest chance to reach/exceed records. We
wouldn`t be surprised if at least downtown Denver snags 70F for a
high.

By Monday, the next weather disturbance will arrive. This will
bring a return of snow to the mountains with modest Pacific
moisture and improving, but still westerly orographics. That will
once again favor the Park Range for at least moderate snow
accumulations of 6-12", with lighter amounts again as we head into
the Front Range and Summit County mountains. It will turn breezy
across the lower elevations, enough for more elevated fire weather
conditions as humidities remain close to critical thresholds
despite slight cooling (but still well above normal temperatures).

As we head into the middle to latter portions of next week, ensemble
mean solutions still show a transition from our current pattern
of weak shortwaves to one of greater trough amplification over the
western CONUS. This will open the door to a more winter-like
forecast for a change, with colder temperatures and potential for
more widespread snowfall. More than half of the ensembles members
have some snow for the plains, but the vast majority of those are
very light (less than 1-2 inches). That said, there are still a
few stronger solutions so we`ll continue to watch for that
potential Thursday into Friday. Given the change to a northwest
flow pattern later this week, that means colder weather (and even
potential opportunity of another snow) into next weekend.

&&

.AVIATION /18Z TAFS through 18Z Sunday/...
Issued at 1032 AM MST Sat Jan 3 2026

VFR through the TAF period. Light S/SSW winds expected to continue
til around 22Z, but then a weak shear zone develops that is likely
to bring variable or light northerly winds to KDEN and KBJC. KAPA
is farther south of that zone and should stay light southerly
through the entire TAF period.

KDEN will see a return to the S/SW winds by 02Z-03Z which will
hold through at least 18Z Sunday. Only later on Sunday (after
19Z-20Z) could it get warm enough to support a breezy W/SW wind
with gusts up to 20 kts. However, confidence is low enough to only
mention that as a TEMPO since the prevailing wind would favor a
turn more diurnal (E/NE upslope) Sunday afternoon.

At KBJC, winds should stay mostly light and VRB but enough
mountain wave enhancement and proximity to the foothills should
support TEMPO gusty west winds to 25-30 kts anytime after 09Z.

&&

.FIRE WEATHER...
Issued at 122 PM MST Sat Jan 3 2026

Record/near record warmth and dry conditions will combine with
downslope winds in/near the foothills and Palmer Divide to create
critical fire weather conditions. However, the areal extent of
those conditions will be limited by a couple factors. One,
parameters are not favorable for the stronger winds to push very
far off the foothills (limited gradient), and two, where the
strongest winds occur humidities will be above critical
thresholds. Therefore, we`ve opted to upgrade to Red Flag Warning
only where the worst combination of humidity and winds will occur,
namely from South Park through the southern Front Range Foothills
and into the Palmer Divide. And even all of those zones won`t
experience Red Flag conditions. However, areas like Cheesman
Reservoir and the foothills of southern Jefferson/Douglas Counties
will see gusts to 30-40 mph and humidity down to 10%, and combined
with recent dryness rapid wildfire spread is possible. For Denver
metro east of I-25, we have high confidence that only a few
channels or brief gusts would occur so we`ve cancelled the Fire Wx
Watch for the immediate Denver area along/east of I-25. Meanwhile,
the western suburbs and Boulder still have a higher risk of
stronger gusts, at least in the morning. However, the main threat
of widespread and stronger gusty winds shifts back into the
foothills during the afternoon when we`ll see the lowest humidity,
so we`ve kept the Fire Weather Watch in effect for the western
suburbs and Boulder.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 10 AM to 5 PM MST Sunday for COZ214-216-
241.

Fire Weather Watch from Sunday morning through Sunday afternoon
for COZ239.

&&

$$

DISCUSSION...20
AVIATION...20
FIRE WEATHER...20

NWS BOU Office Area Forecast Discussion