750
FXUS65 KBOU 281909
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1209 PM MST Fri Nov 28 2025

.KEY MESSAGES...

- Real taste of winter this weekend, with much colder temperatures
  and at least light snow/flurries arriving tonight.

- Slick travel in spots across the I-25 Corridor and plains late
  tonight through early Saturday morning. Mountains will likely
  have more significant impacts with several inches of snow.

- Second round of snow for the mountains Sunday, with another
  round of light snow/flurries possibly spreading onto the urban
  corridor and plains (30-50% chance) late in the day.

&&

.UPDATE...
Issued at 323 AM MST Fri Nov 28 2025

Forecast is on track with the arrival of winter temperatures and
some snow tonight. However, there`s still uncertainty with
whether we finally get our first measurable snow on the plains.

Overall, the short range forecast models remain in pretty decent
agreement. There has been a slight bump in QPF for the mountains,
as we will get into the left exit region of the upper level jet
late this afternoon and evening. Despite limited moisture, the
increased QG lift is expected to support snow development in the
high country - first in the northern tier of mountains late this
afternoon spreading to the I-70 Corridor by early evening. As that
first round of synoptically supported snow and generally less
favorable orographics moves out, another round of increased
snowfall should arrive toward midnight as stronger cold advection
arrives in conjunction with better moisture and upper level trough
(currently in the Pacific Northwest). Lapse rates are quite
unstable (near 7 C/km), and with stronger orographics from the
WNW an enhanced period of accumulating snowfall is expected. While
some short range CAMs (convective allowing models) produce
runaway snow totals, we ran the local orographic snow model from
the synoptic model data which supports a 4-8" snow forecast most
areas, with locally heavier amounts in the northern Gore and Park
Ranges. Using a blend of QPF and modified snow to liquid ratios
(SLRs), those are essentially the amounts we`ve come up with in
the latest deterministic forecasts. Travel impacts will start
with the onset of more meaningful snowfall once the sun sets, and
given considerable post-holiday traffic, we`ve issued a Winter
Weather Advisory for our mountains starting 5 pm and lasting til 8
am Saturday. We do see a quick shutoff, even for the mountains,
Saturday morning as we quickly turn strongly subsident and drier.
That should allow better return travel conditions if not traveling
during the daylight hours today.

Now, for the I-25 Corridor and plains...A strong cold front will
arrive shortly after midnight tonight ushering in sharply colder
temperatures (source region in southern Alberta currently in the
teens). While most short range models don`t show the front
arriving til 3 am in Denver, I would not be surprised at all if
it`s a couple hours earlier than that considering we`re already
seeing a push into northern Montana. Whatever the case, it`s time
to get ready for winter cold that will last through the entire
weekend. With regard to snow, there are still some conflicting
signals in some models. One of the most detrimental would be a
later arrival of the front and thus any shallow upslope would be
fighting stronger subsidence. Even then, these fronts typically
produce at least some shallow light snow so we`ll maintain the
relatively high chances (~50-70%) for the majority of the lower
elevations late tonight. I`d like to go higher based on enough
forcing from the front, but there are also mixed signals regarding
depth of moisture and a rather quick arrival of subsidence.
Whatever the case, this won`t be a significant snowfall by any
means (most likely scenario for an inch or less). That said, as
temperatures drop it would still be cold enough to support a
relatively fast freeze and locally slick roads (where it does
snow) into early Saturday morning. Highest probabilities of that
would be roughly Boulder-Denver-east central Colorado (60-70%
chance), and lower probabilities (<50% chance) Greeley - Fort
Collins. Despite high temperatures staying at/below freezing,
enough solar insolation will get rid of any slick travel
conditions in the lower elevations by mid-late morning Saturday.

No other significant changes in the ensemble data for the later
periods, offering up additional chances of snow later Sunday, and
then again toward Wednesday.

&&

.SHORT TERM /Through Friday/...
Issued at 209 PM MST Thu Nov 27 2025

Zonal flow aloft with subsident flow has made for a pleasant
Thanksgiving. Most of the Denver metro has temperatures in the 50s
while the rest of the plains are in the 40s. Tonight, there will be
mild temperatures with dry conditions.

On Friday, the flow aloft will increase as a shortwave trough
approaches Colorado from the west. Stronger winds in the mountains
with gusts up to 50 mph are possible beginning midday. Slight low
level warm air advection will increase high temperatures tomorrow.
Denver will see a high in the low 60s with slightly cooler
temperatures across the rest of the plains. Moisture will increase
from the west throughout the day and snow showers will begin in the
mountains after about 2pm. PoPs and QPF were increased from 2-5pm to
account for this arrival of the snow showers. The plains will be dry
throughout the day.

&&

.LONG TERM /Friday night through Thursday/...
Issued at 209 PM MST Thu Nov 27 2025

Mild conditions and breezy west winds linger into the evening
hours across the mountains, foothills, and nearby plains.
Scattered rain showers are expected to form ahead of the
approaching system. The cold front surges south into northern
Colorado around midnight and then races southward through the
area. Temperatures rapidly fall, becoming cold enough for snow not
long after the front moves through. Most models and ensemble
members show snow late Friday night and early Saturday. However,
precipitation amounts are quite light, 0.05-0.10 (in), which seems
reasonable for this quick moving moisture starved system.
Northerly downslope winds off the Cheyenne Ridge could produce
enough drying to squash snowfall to the north of Denver from Fort
Collins to Greeley to Fort Morgan. Thus our snowfall forecast for
the lower elevations is zero to 2 inches. For the mountains, a
little more snow is expected with up to 6 inches in the northern
mountains.

Snow comes to end mid to late Saturday morning. Roads could be
slippery for a few hours Saturday morning where it snows. Clearing
will help melt the snow off the roads, but temperatures will be
cold with highs in the upper 20s to mid 30s across northeast
Colorado.

Skies cloud up Sunday ahead of the next system nearing the area
from the Pacific Northwest. The storm track is farther west as it
dives southeastward. This should result in a little more snow for
the mountains than the previous system. Snow is expected to
develop during the morning or early afternoon across the mountains
and then slowly increase into the evening hours. If traveling in
the mountains Sunday, expect road conditions to slowly worsen
through the afternoon and early evening hours, so best to travel
earlier in the day. Some of this snow may spread east onto the
plains, where light amounts will be possible again.

For Monday, north to northwest flow aloft will prevail behind the
exiting trough. Light snow may linger into the morning hours over
the mountains, while the main area of snow shifts south and east
of the area. Temperatures are expected to remain cool with highs
in the 30s across northeast Colorado. The next storm system
travels southward across British Columbia Monday, and then south-
southeast across the intermountain west Tuesday. Models show a
wide range of solutions with this system. Some models show a more
westerly track taking this system south across the Sierras. At the
other end of the spectrum, other models show this system
splitting. One piece of energy travels from the Pacific Northwest
to the Central Plains. The other part dives south-southeast to the
Four Corners. As far as Colorado weather goes, expect a warm up
Tuesday as flow aloft backs to the west ahead of this system. The
cooler temperatures and a chance for snow returns for Wednesday as
the trough will be near or over the region. With this system
traveling along the spine of the Rockies, moisture is expected to
be limited with snowfall amounts on the light side again. Cooler
temperatures likely continue into Thursday and depending on the
speed of this system, the chance for snow could continue into
Thursday as well.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1139 AM MST Fri Nov 28 2025

Very light southwest winds or variable winds are expected at all
three terminals for much of the afternoon. A weak boundary is
lurking to the northeast of DEN which could shift winds to the
northeast later this afternoon.

Tonight, some mid level frontogenesis will create rain showers
(possible mixed with snowflakes) around the terminals between
04-08Z. Minimal impacts are expected from these showers as
ceilings could decrease to 6,000 feet but a PROB30 was added.

A cold front will move through the terminals between 07-10Z. Gusty
winds are expected behind it with gusts up to 35 knots for brief
periods. Low clouds are likely to form with 2,000-3,000 foot ceilings
that could briefly get as low as 1,200 feet. Model data is
becoming more uncertainty about whether it will snow at the
terminals or not. There is still a 60% chance light snow falls but
the chance it remains dry seems to be increasing. If the snow does
occur, visibility would be in the 1-3 SM range.

Low ceilings will break in the mid to late morning hours with VFR
conditions expected the rest of the day Saturday. Northeast winds
will continue throughout the majority of the day with gusts up to
25 knots.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 5 PM this afternoon to 8 AM MST
Saturday for COZ031-033-034.

&&

$$

UPDATE...20
SHORT TERM...Danielson
LONG TERM...12
AVIATION...Danielson