174
FXUS65 KBOU 300011
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
611 PM MDT Thu Oct 29 2026

.KEY MESSAGES...

- Mild and mostly dry through the work week.

- Unsettled weather returns late this weekend and early next week.
  Mountain snow is likely (>70% chance) above 8500ft during this
  time. High uncertainty remains for the foothills and plains.

&&

.DISCUSSION /Through Thursday/...
Issued at 1257 PM MDT Thu Oct 29 2026

We`re looking at another potential fog event tonight. Light winds
and surface conditions near or at saturation could lead to dense fog
development overnight tonight and tomorrow morning. High res models
have fog developing over Kansas and the eastern plains and a surface
cyclone to the northeast of Denver. This circulation could usher
fog right into the urban corridor from the north. High res
ensembles currently have a medium to high chance (50% to 80%) that
patchy dense fog (vis <0.5mi) will develop across the urban
corridor, northern I-25 corridor, and portions of the eastern
plains. This could lead to dangerous travel conditions for the
Friday morning commute. A similar fog setup will be in place for
Saturday morning, leading to additional fog and travel concerns
for portions of the urban corridor and eastern plains for Saturday
morning.

A shortwave will move to the southeast of the area on Friday. While
most of the forcing and precipitation from the shortwave will be to
our east/southeast, our far eastern counties could be clipped by a
weak shower or two. No impacts are expected. On Saturday, another
shortwave will move through the southwest flow aloft bringing
isolated to scattered showers to our higher terrain in the
afternoon.

On Sunday, things start to get more uncertain. Late Saturday into
early Sunday there will be two upper level low pressure systems off
the west coast of North America. One will be off the coast of Baja
California while the other will be closer to the Pacific Northwest.
The southern one will bring significant moisture transport into the
four corners region on Sunday, bringing our PW values into the 200%
to 300% of normal range for Sunday and Monday. The northern system
will dig southeast, phasing with the other system sometime Sunday or
early Monday. Models tend to struggle with exactly how two troughs
phase together, which brings high uncertainty on the exact path of
the resulting system and the potential impacts for our area.

There will be widespread upper level support for showers ahead of
the approaching trough. Right now, peak QG forcing looks to be
Monday afternoon, which is when we`d expect the most widespread
showers. However the timing and strength of the trough could very
well change between now and late this weekend. A strong surface
front will move through sometime late Sunday and Monday, bringing
strong north/northwesterly winds to the plains. The current forecast
upper level and lower level winds, don`t look great for
additional topographic forcing and higher precip totals, with the
exception of maybe the Palmer, which tends to do better with
northerly winds than the rest of our area. However, we will be
keeping an eye on the development of the surface low and any
potential eastward turning of the winds, which would impact precip
totals in our area. Currently, liquid precip amounts look to stay
under an inch for our area, with much of the area remaining below
half an inch. In terms of snow, snow levels are forecast to start
out around 10kft or 11kft, dropping closer to 7,500ft by Tuesday
morning. Models remain too warm for snow on the plains, with the
NBM giving the plains a 0% chance of any measurable snowfall.

This system will move off to the east on Tuesday, bringing weak upper
level ridging and drier conditions. Northerly surface winds will
continue for Tuesday and Wednesday, helping keep temperatures near or
below normal.

&&

.AVIATION /00Z TAFS through 00Z Saturday/...
Issued at 536 PM MDT Thu Oct 29 2026

VFR conditions expected to persist through the evening before fog
develops and a Denver Cyclone pulls it south into KDEN and KBJC
for the overnight and first half of Friday morning. For the next
few hours, guidance portrays the cyclone moving northeast across
KAPA/KDEN that makes for some uncertainties in the wind forecast
while this occurs. The current TAF portrays the highest confidence
solution, with a few hours of northeasterly winds from now until
around 3Z at KDEN, before turning clockwise to the SSW by about
4Z. KAPA will likely see light and variable winds develop in the
next hour before they also turn to the SSW by around 4Z. KBJC will
likely see a NW transition by around 2Z before becoming light and
variable through late Friday morning.

Fog is likely to make it into KDEN/KBJC sometime between 9Z-10Z,
with it getting within the vicinity of both TAF sites between
7Z-8Z. Expecting visibility to drop down to 1/4SM or less once
the fog settles in. KAPA remains a wildcard with low confidence in
fog making it that far south, but it should make it within the
vicinity by around 9Z, and will have to monitor trends and
conditions to potentially add a PROB30 or TEMPO in the coming
hours. Guidance does show a fairly quick clearing between 15Z-16Z
Friday morning.

Friday looks similar to today, with NE winds developing by early
afternoon, becoming easterly and slightly increasing in magnitude
around 21Z, with another cyclone potentially moving across the TAF
sites Friday evening. While it`s outside of this TAF package, it
does look like we will have potential for fog to return early
Saturday morning that could at least make it into the vicinity of
both KBJC and KDEN.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory from 10 PM this evening to 8 AM MDT Friday
for COZ046-047.

&&

$$

DISCUSSION...AP
AVIATION...9