839
FXUS65 KBOU 050053
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
553 PM MST Sun Jan 4 2026

.KEY MESSAGES...

- Winds and fire danger decreasing quickly into this evening.

- Breezy again Monday afternoon through Tuesday with elevated fire
  weather conditions.

- Round of light to moderate snow for the mountains is still on
  track for Monday and Monday night, once again favoring the Park
  Range.

- Lower elevations will remain dry and mild through Wednesday.

- Still expecting colder and more unsettled weather returning for
  Thursday and Friday.

&&

.DISCUSSION /Through Sunday/...
Issued at 216 PM MST Sun Jan 4 2026

The bulk of the stronger winds have retreated to the foothills and
Palmer Divide pretty much as expected this afternoon. With the
relaxing flow aloft and loss of daytime heating, those winds will
decrease rather markedly by early this evening.

The next weather system will arrive in the mountains Monday
morning. That disturbance will be a weakening shortwave moving
across the Great Basin in advance of a deeper trough dropping
south in the eastern Pacific. Mid level moisture and instability
will be increasing with this ejecting shortwave, advecting in
today`s abundant mid level moisture from California and the Great
Basin. Snow will develop during the morning hours across the
northern Colorado mountains, and then continue through much of
Monday night before decreasing. While orographics aren`t terribly
impressive with a WSW flow initially, it will favor the northern
Gore and especially the Park Range. There will be enough mid
level moisture and instability to bring snow into the I-70
Mountain Corridor/Summit County, but flow only becomes about due
west which isn`t great for significant accumulations there. As a
result, we`ve issued the Winter Weather Advisory only for Zone 31
(the northern Gore and Park Ranges) where 6-14 inches of snow is
expected. The northern Front Range mountains will likely see
lesser amounts (closer to 3-8 inches), while totals along the I-70
Mountain Corridor and Summit County will be closer to 2-5 inches,
although the proximity of the jet coupled with mid level
instability does offer up a chance for more. Snow is expected to
decrease a little faster than earlier anticipated, now looking
more like late Monday night, with only scattered lingering light
snow showers by then that last into Tuesday.

On the plains, dry conditions will persist with deep westerly
downslope flow in place. It will also be breezy at times starting
tomorrow morning in/near the foothills, and then across most of
the remaining plains tomorrow afternoon. Despite some cooling
aloft, the downslope will promote deep mixing and thus
temperatures still warming to well above normal levels (lower 60s
for the plains and I-25 Corridor). A little more cooling is
anticipated Tuesday with mostly upper 50s for the plains, but
that`s still nearly 15 degrees above normal. With the continued
dry and breezy conditions, fire danger will be elevated but we
expect to stay shy of critical Red Flag conditions thanks to the
slight cooling.

Wednesday appears to be in between systems, although a few snow
showers will still be possible in the mountains and generally
light breezes and still mild temperatures for the plains.

The next system of interest is still on track to move into the
forecast area Thursday into Friday. While there is considerable
uncertainty in the details it does appear the main moisture laden
system coming across Baja will stay far too south to impact
Colorado. Thus, we`ll be impacted by the colder northern stream
energy dropping southeast across the Northern/Central Rockies and
Great Basin. However, there is a modest uncertainty in the track
and intensity of this feature. Most ensembles still show a light
snow event for most of the forecast area (and that seems the most
likely solution at this time), while just a couple have a few
inches. About 30% remain dry. Temperatures will be cold enough to
support entirely snow, if it precipitates.

It was interesting to note the ENS was most bullish with regard to
the snow chances, and it was also a tad slower. That slower
solution then allows a secondary shortwave to drop into the back
side of the developing Great Lakes low. If that`s the case, then
another reinforcing shot of cold air would be expected Saturday.
There`s a 30-40% chance that keeps high temperatures at/below
freezing for Friday and/or Saturday.

Beyond that, there`s a scary block that`s forecast to develop
over the western U.S. early the following week. That would just
send us back to the dry weather pattern we experienced through
much of this winter so far.

&&

.AVIATION /00Z TAFS through 00Z Tuesday/...
Issued at 542 PM MST Sun Jan 4 2026

VFR conditions through the TAF period. Light northeast winds will
eventually become southeast this evening before drainage winds
take over overnight.

Winds at all terminals will be either southwest or west during the
morning hours with speeds generally between 6-12 knots. With mild
conditions at the surface tomorrow afternoon, good mixing will
help to bring down gusty westerly winds aloft. Gusts may reach
30-35 knots at times at all airports. West winds will weaken
around sunset and eventually drainage winds will return tomorrow
evening.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 5 AM Monday to 5 AM MST Tuesday for
COZ031.

&&

$$

DISCUSSION...20
AVIATION...Danielson

NWS BOU Office Area Forecast Discussion