National Weather Service Forecast Discussion

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193
FXUS65 KBOU 210136
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
636 PM MST Sat Dec 20 2025

.KEY MESSAGES...

- Snow lingering across the mountains through this evening. Some
  travel impacts, especially over the Park Range and northern
  Front Range.

- A little warmer Sunday with winds picking up across the higher
  elevations by the afternoon or evening.

- Warmer, drier pattern returns again for next week. Some hints
  of a more wintry pattern in the mountains in the latter half of
  the week?

&&

.DISCUSSION /Through Saturday/...
Issued at 137 PM MST Sat Dec 20 2025

This morning`s backdoor cold front was a little more robust than
most guidance had advertised. The post-frontal stratus also helped
keep a deep inversion in place from 800-700mb (as noted from ACARS
soundings) and unsurprisingly temperatures have been cooler than
thought. Still, most locations were in the 50s earlier in the
morning and so our daily high temperatures and our afternoon
"high" temps will be pretty different.

Across the mountains, we continue to see one dominant band of snow
stretching across the northern tier of counties in our CWA.
Indeed, SNOTEL data confirms that a majority of the accumulating
snow with this event has been in the Park Range and northern Front
Range. Eventually we may see a secondary band try to develop
further south, but most if not all of the winter impacts will be
north of I-70. A little bit of moisture lingers over the mountains
into tomorrow but most of the accumulating snow will end by around
midnight tonight.

The flow aloft is expected to weaken a bit as we slowly start to
see a ridge build to our south. Drier air and slightly moderating
mid-level temperatures should allow temperatures to warm up into
the 50s to low 60s across the plains.

We will see the weather pattern across the country transition
from a westerly zonal flow to ridging over the south central and
southeast part of the country early next week. As the upper level
high builds northward, flow aloft across Colorado weakens. Flow
aloft also turns southwesterly over the Rockies and across the
western states as the ridge builds northward and an upper level
trough forms off the Pacific Northwest and British Columbia coast.
This will set up a very wet pattern for California. For Colorado,
the first part of the week will be mild and dry as the flow aloft
weakens and transitions to the southwest. Temperatures will be
well above normal with record highs possible on Monday. These very
warm temperatures continue through Christmas with only a slight
(5-10F degree) cool down on Tuesday.

The chance for snow returns to the mountains late Wednesday and
continues the rest of the week and into next weekend as Pacific
moisture finally reaches Colorado. Southwest flow aloft tends to
favor the west and more so the southwest mountains of Colorado.
The mountains of Grand and Summit Counties tend to be shadowed by
the mountains to the west, thus lighter snowfall amounts are to be
expected here than across western Colorado. The Gore and Park
Mountains in north central Colorado can see better snow under this
southwest flow. For the foothills and plains, the westerly
downslope flow will result in continued dry conditions. Winds will
be gusty at times in the mountains and foothills, however the
threat for strong/high winds looks very low at this time.

&&

.AVIATION /00Z TAFS through 00Z Monday/...
Issued at 634 PM MST Sat Dec 20 2025

The southeasterly winds currently at DIA are expected to become
normal drainage winds by 03Z later this evening. Cross sections
and soundings do no indicate any low Stratus or reduced
visiblities Sunday morning at DIA. There should not be any ceiling
issues.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight MST tonight for COZ031-
033-034.

&&

$$

DISCUSSION...Hiris/12
AVIATION...66

NWS BOU Office Area Forecast Discussion