813
FXUS65 KBOU 271749
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1149 AM MDT Tue Oct 27 2026

.KEY MESSAGES...

- Warmer and mostly dry much of this week.

- Unsettled weather potentially returning late in the weekend and
  early next week, with a 20-30% chance of season`s first snow in
  lower elevations towards next Tuesday.

&&

.UPDATE...
Issued at 535 AM MDT Tue Oct 27 2026

Dense fog has developed overnight across the plains, with
visibility dropping as low as 1/4 mile in some locations. A Dense
Fog Advisory is in place until 9AM for the I-25 corridor and
adjacent plains, and until 10AM for the northeast corner, with
hazardous travel conditions expected for the morning commute. Take
it slow out there and remember to use your low beams!

&&

.DISCUSSION /Through Monday/...
Issued at 1149 PM MDT Mon Oct 26 2026

It`s relatively quiet across the forecast area this evening. We`re
just starting to see the first bit of fog/mist develop across
Lincoln county, and stratus/mist has slowly developed along the
northwest Denver metro/northern I-25 corridor over the past couple
of hours. We still expect fog to become more widespread across the
plains overnight tonight, with some dense fog likely over portions
of the I-25 corridor later tonight through the AM commute Tuesday.
Some dense fog advisories may be needed overnight, but would like
to see the fog actually develop before trying to pinpoint where
the dense fog is compared to the less impactful low stratus.

Fog and stratus should erode pretty quickly during the morning
hours Tuesday. Like today, temperatures will be slow to warm up
during the day, with highs generally in the low to mid 60s -
potentially a bit cooler for the northern I-25 corridor.

The rest of the upcoming week looks quiet, as dry
west/southwesterly flow aloft continues. A return to a more active
pattern begins towards the end of this week or this weekend. A
weak but well-defined shortwave lifts north out of New Mexico
into the central Great Plains on Friday. It looks like this will
track just to the east of our forecast area, but there should be
an increase in cloud cover along with a chance of showers along
the far eastern plains, with better chances in Kansas/Nebraska.
Around the same time, some moisture from the Pacific reaches
western Colorado either Friday or Saturday, leading to some
scattered light rain/snow showers across the mountains to start
the weekend.

A stronger, more organized system could approach the region by
the end of the weekend into next week. A strong upper trough is
projected to crash southeastward towards our forecast area,
potentially interacting with the moist subtropical jet streak. As
the previous shift noted, there is quite a bit of spread across
guidance. Several of deterministic models over the last 12 hours
have advertised the idea of a stronger upper low moving across
Colorado, though many still remain rather quiet across the state
with a disorganized trough quickly moving through. Ensemble
guidance continues to show a wide distribution of solutions,
ranging from almost no precip in our CWA to some rather juicy (and
at times, snowy) scenarios. Within the ensemble distribution,
there has not been a significant trend in any direction. Given
that we`re still several days out, most of these cycle to cycle
changes are simply noise, and it will take some time before a
clear trend emerges. Still, it`s worth monitoring for the few
days in an otherwise quite forecast period.

&&

.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1145 AM MDT Tue Oct 27 2026

VFR conditions are expected through the TAF period. There is a
low (~20%) chance that FG/low stratus could make it into KDEN
tonight explained in more detail below...

Fog was prevalent and quite dense at KBJC and KDEN for several
hours this morning and has finally been lifting over the last 2-3
hours. Each site is back to VFR conditions at this time. There is
a channel of stronger winds (gusts up to 20 kts) affecting KAPA,
but these are expected to lighten up in the next 60 to 90 minutes.
Additionally, satellite and web cameras show that there is a
mountain wave cloud near and west of KBJC. For this afternoon,
winds will turn to the east and stay under 12 kts. At KDEN, winds
could increase a bit to 10-15 kts later this afternoon. A weak
Denver cyclone looks to form tonight in Weld County causing rather
variable winds this evening. At this time, the cyclone is
expected to move far enough away from KDEN that drainage flow
occurs by about 5z- perhaps a bit later at KBJC- at all three TAF
sites through the overnight. Model guidance is in good agreement
that this would keep an fog to the north and east of KDEN from
far northern Adams County into Weld County. If the cyclone were to
be positioned further south, some fog could make it into KDEN and
approach KBJC, but there is only about a 20% chance that this
scenario could play out tonight. We have covered this potential
with a lengthy period of VCFG and a few low clouds in the TAF.

For tomorrow, winds will be vrb and light in the morning and
transition to an east/southeast wind with speeds slightly
increasing to 8-12 kts by the late afternoon.


&&

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

&&

$$

UPDATE...9
DISCUSSION...Hiris
AVIATION...MV

NWS BOU Office Area Forecast Discussion