222 
FXUS65 KBOU 122010
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
210 PM MDT Mon Oct 12 2026

.KEY MESSAGES...

- Change in the weather to cool, wet conditions is still on track.

- Showers will become more numerous in and near the mountains late
  Tuesday and Tuesday night, but then more widespread rain and
  mountain snow still on schedule for Wednesday - Wednesday night,
  before winding down Thursday. 

- Several inches of snow expected for the mountains above
  9,500-10,000 feet with some travel impacts late Wednesday -
  Thursday morning. Lighter snow and at least a dusting into the
  mountain valleys and higher foothills. 

- Drier and warmer again for next weekend. 

&&

.DISCUSSION /Through Monday/...
Issued at 210 PM MDT Mon Oct 12 2026

A cold front will ooze southward across northeast Colorado
tonight, ushering in the first wave of much cooler temperatures 
that will become increasingly chilly through Wednesday.
Precipitation chances will also be increasing through Wednesday 
and Wednesday night, most likely bringing a light to moderate 
rainfall for most of the lower elevations, and accumulating snow 
and the season's first travel impacts for the higher mountains. 

For tonight and Tuesday, the main shower chances will remain over
the mountains with the greatest chances closer to the upper level
low spinning over the Great Basin. The majority of these should
impact the far western mountains (in Jackson and Grand Counties)
being near the upper level jet and deeper moisture plume. There is
a 30% chance that a few showers could spill across the northern
foothills as one speed max ejects out of that trough axis late
tonight/early Tuesday morning. On the plains, mostly dry conditions
will prevail but low clouds will overspread most of the plains 
behind tonight's cold front. While low clouds are expected to 
slowly burn off/lift on Tuesday, we'll be entrenched in the cooler
low level airmass. We've knocked a couple more degrees off our 
forecast high temperatures and more in line with the cooler 
guidance, with upper 50s to mid 60s expected over most of the 
plains (coolest over the far north/east). 

For Tuesday night and Wednesday, the upper level low in the Great
Basin will start to eject slowly eastward toward the Four Corners
region. This means increasing upper level support and QG forcing.
However, cross sections still show a dry slot aloft (above 600
mb), that could certainly curtail widespread shower development
despite the synoptic lift and weak upslope. Normally, the lift
would be sufficient to aid moistening so will have to watch this.
If it is still too dry on Wednesday, we think Wednesday night will
offer up the best opportunity for more significant and widespread
precipitation as the column fully moistens and QG lift remains in
place. The duration of this is still in question, however, as some
models track the upper level low just north of Denver, while 
others would support a longer duration event with the upper level 
low passing just to our south. Ensembles are generally mixed, 
with >70% chance of 0.50" or more along the I-25 Corridor and 
northern plains, and >50% chance of 1" for the Front Range 
Mountains and Foothills. The EPS was generally trending on the
higher side while the GEFS was slightly lower (essentially
opposite the operational models). Precipitation amounts and 
chances would decrease to the south and east. Temperatures will be
quite chilly Wednesday, with highs struggling (and doubtful!) to
reach the 50 degree mark in Denver and the plains.  

Regarding mountain snow: The track of the upper low is favorable
for QPF (as discussed in the probabilities above). Temperatures 
will also be turning colder as the core of the upper low 
approaches and passes overhead Wednesday night into Thursday 
morning. At this point, model averages seem reasonable bringing 
minimum snow levels down to 8000 feet, but a few of the colder 
solutions bring snow down even further and closer to 6500-7000 
feet (20% chance). For the majority of the event, they will be 
higher than that so heaviest total accumulations would likely 
remain above 9500 feet, but can't rule out a couple inches down 
closer to 8000 feet. Several inches of snow are likely and the 
latest QPF/snow ratio forecasts would suggest a fairly high (70%)
probability of 6-10" in the higher mountains and over the higher 
passes. Thus, a Winter Weather Advisory may be needed as we get 
closer to the main mountain snow event late Wednesday - Thursday 
morning.

While there is uncertainty in how the upper level low finally
ejects (seems to be a combination of ejecting it into the Central
Plains with another piece shearing into the Desert Southwest), we
have increasing confidence that precipitation will be ending from
north to south on Thursday. That will set the stage for clearing
skies and likely the season's first light freeze/frost over most 
of the plains Thursday night and early Friday morning. 

Beyond that, upper level ridging and dry weather is largely
anticipated for the weekend ahead. That pattern would support 
temperatures returning to above normal levels with highs pushing 
back into the 70s for the I-25 Corridor and adjacent plains. 

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1150 AM MDT Mon Oct 12 2026

VFR conditions through late tonight before low stratus becomes 
likely early Tuesday. Winds will be south to southwest and gusty 
this afternoon with some gusts as high as 20-25 kts at KDEN and
KAPA. KBJC has some southeast winds at this time, but will also
turn to the southwest later this afternoon with some lower wind 
speeds than at the other two sites. The chance for southeast winds
to make it into KDEN over the next hour or so is low as seen on 
the latest velocity trends.

Guidance, including BUFKIT soundings and MOS guidance, is in good
agreement about low stratus for the sites on Tuesday morning. A 
pre-frontal push is slated to arrive around 5/6z turning winds to
the northwest before the front pushes through from north to south
around 10-12z and turns winds more to the north. Ceilings will 
start to lower after 5z, but then drop to as low as 1000-2000 ft 
AGL after 10z and lasting through at least 16z in general. As of
now, ceilings look lowest from ~13-16z Tuesday. Confidence is 
highest at KDEN with a shorter window for the low stratus 
currently expected at KAPA and slightly higher ceilings at KBJC.

Winds for tomorrow afternoon turn to the east for much of the
afternoon with speeds around 8-12 kts and ceilings slowly rising 
through the afternoon. Near the end of this TAF period, ceilings 
are again expected to lower ahead of the incoming storm system for
late Tuesday into at least Wednesday.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...20
AVIATION...MV