901
FXUS65 KBOU 310027
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
627 PM MDT Fri Oct 30 2026

.KEY MESSAGES...

- Areas of fog again tonight across northeast and eastern
  Colorado.

- Mild and mostly dry through Saturday.

- Unsettled weather returns late Sunday and Monday.Mountain snow
  is likely (>70% chance) above 8500ft during thistime. High
  uncertainty remains for the foothills and plains.

&&

.DISCUSSION /Through Friday/...
Issued at 111 PM MDT Fri Oct 30 2026

Water vapor satellite imagery showsa shortwave trough over
southern California bringing widespread clouds and scattered rain
showers to the Desert Southwest. Ahead of this, there is a dry
slot which will result in mostly clear skies for northeast
Colorado through this evening. High clouds then increase late
tonight and persist through Saturday morning. At the surface, the
pattern changes very little as a surface trough remains near the
base of the foothills, which will help keep low level moisture in
place over northeast Colorado. This will lead to another round of
fog late tonight and Saturday morning. The mid and high clouds
associated with the shortwave trough tracking east-northeast
across the intermountain west will shift east of the area midday
Saturday. Mostly sunny skies are expected during the afternoon,
helping to push temperatures into the upper 50s to mid 60s across
northeast Colorado.

Southwest flow aloft will increase during the day Sunday as two
systems off to the west take aim at the region. The first one
system, a shortwave trough moves across southern California and
tracks east-northeast Sunday and Monday. This system will run
ahead of the second system on Sunday, carrying subtropical
moisture with it and, like many of the recent systems, bring
moderate to heavy rain to the Desert Southwest and Four Corners
Region. For north central and northeast Colorado, this has
resulted in scattered showers over the mountains and just cloudy
skies for northeast Colorado. The second system tracks eastward
across Oregon and northern California Sunday and then moves across
Colorado Monday. The best chance for rain and mountain snow will
come late Sunday night and Monday as the main trough moves
overhead. The snow level starts off high, above 11,000 feet but
quickly lowers to 8,500 to 9,000 feet by Monday morning. Snow is
expected to continue into Monday night when flow aloft turns
north-northwesterly, a somewhat favorable direction for orographic
lift across the north central mountains. Temperatures will be
cool Monday due to the overhead trough and cloud cover. Northerly
flow behind the trough Tuesday will keep temperatures cool with
highs in the 50s with dry conditions.A few earlier model runs
combined these two systems over the Central Rockies producing a
strong storm system, but this scenario now looks very unlikely.

The broad troughiness shifts east of the area sometime late
Tuesday/early Wednesday with ridging replacingit, most likely for
Wednesday. We expect to see a bump up in temperatures with dry
conditions. The ridging is expected to progress east of the area
on Thursday. What replaces it is still unclear. The next upper
level trough moves over the western states onThursday. Still very
little model agreement on the placement, strength, and track of
the upper level trough for Thursday and Friday. For the forecast,
temperatures should be near normal. We will have some low PoPs in
the mountains and keep the plains dry for now.

&&

.AVIATION /00Z TAFS through 00Z Sunday/...
Issued at 551 PM MDT Fri Oct 30 2026

Some small adjustments have been made for potential impact timing
at all TAF sites with this TAF package. Fog is still anticipated
to develop overnight tonight and stick around through late
Saturday morning. In addition to KDEN/KBJC`s previously advertised
expected impacts, KAPA now has increased chances of potential
impacts as well, with a TEMPO now included in their TAF beginning
at 13Z. Additionally, guidance has started to move up the arrival
time of low stratus to as early as 5Z tonight at KDEN, so a TEMPO
has been included to account for this change. Similar to last
night, a cyclone is expected to bring light and variable winds to
the TAF sites, and fog is likely to be within the vicinity of
KDEN/KBJC sometime between 9Z-10Z, with prevailing LIFR conditions
anticipated by 12Z. There are still some uncertainties on if
there is an earlier development at KDEN, as latest hi-res guidance
is hinting at this potential, but we would like to see what the
0Z model trends give us before making any further adjustments.
KAPA is, once again, the wildcard, but it is starting to look like
NNW winds have a good chance of pulling the fog further south by
early Saturday morning that they could see a few hours of LIFR
conditions between 13Z-16Z. Conditions should start to improve
across all the TAF sites late Saturday morning, between 16Z-18Z,
with VFR conditions likely to return by 20Z.

Light northerly winds are expected by late Saturday morning,
becoming NE for the afternoon, and turning to the south for the
overnight hours.



&&

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

&&

$$

DISCUSSION...BM
AVIATION...9

NWS BOU Office Area Forecast Discussion