558
FXUS65 KBOU 241159
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
559 AM MDT Sat Oct 24 2026

.KEY MESSAGES...

- Cooler weather returns this weekend with chances for rain,
  mainly for the eastern plains.

- Still a rather uncertain precipitation forecast for much of the
  I-25 corridor and mountains... but increasing chance for light
  rain/snow Saturday night and again Sunday night.

- A cool start to next week, but a warming and drying trend likely
  by mid-week.

&&

.DISCUSSION /Through Friday/...
Issued at 1110 PM MDT Fri Oct 23 2026

Another day closer to this weekend`s storm system, and almost all
of the details regarding precipitation potential remain unclear.

We`ll start with what we know. A fairly strong surface cold front
is still on track to arrive Saturday morning, sometime not too
long after sunrise for most of the Denver metro. Unlike many of
our cool season fronts, it will take some time to saturate the low
levels, meaning that low/mid cloud cover will be slow to develop
in the morning before stratus becomes more widespread during the
afternoon hours. High temperatures Saturday afternoon may only
rebound into the low 50s across most of the lower elevations.

Meanwhile, the main upper level low of interest is spinning over
far southern California tonight, and should track off to the north
and east during the day Saturday. Today`s trends have been towards
a slower (further west) and slightly stronger low. As a result,
the deeper plume of moisture also ends up a touch further west.
Most of tonight`s CAMs throw a large precipitation shield from
south to north during the afternoon and evening hours, with modest
(~0.05-0.25") amounts as far west as the foothills and as far
north as a Longmont - Greeley line. However, most of the
global/regional deterministic guidance is not nearly as bullish
with this potential, nor are most ensemble members during this
time. It will be worth watching if either of these solutions fold
with the 06/12z guidance later tonight. Of note - some of these
wetter solutions also bring in favorable south-southeasterly flow
into Park County where there could be a few inches of snow
through Sunday AM.

By Sunday, forecast guidance really likes the idea of spinning up
a well-defined Denver cyclone. As noted in the previous discussion,
temperatures will probably warm up into the upper 50s to low 60s
where clear skies develop, while many locations along the northern
I-25 corridor and northeastern plains remain socked in stratus
and see temperatures similar to Saturday. The upper low is
expected to pivot across the region from Sunday afternoon into
Monday morning. Again, one notable trend is to have this low be
stronger/better defined, with a negatively tilted trough axis
noted by Sunday night. As a result, the surface low over eastern
Colorado ends up a bit more defined and low-level upslope is a
touch stronger, while QG ascent is placed over our forecast area.
Again, guidance is all over the place with the actual track of
both the upper level and surface features. The ECMWF has been
relatively consistent placing more substantial QPF over our
central/northern mountains into the adjacent plains, while many of
this evening`s CAMs kept most of the meaningful QPF closer to the
CO/WY border. Our preference here was closer the NBM/ECMWF
ensemble mean, though I would anticipate more changes to the
forecast over the next 24-36 hours. At the very least, there`s two
well-defined periods for potential rain (and mountain snow) this
weekend for those looking to see their favorite hydrometeors fall
out of the sky.

Once the trough lifts to the north of our area Monday, we`ll re-
enter another period of dry weather through most of the week. Cool
temperatures are still expected to stick around on Monday, with a
warming trend by Tuesday under a broad warm air advection regime.
Highs most days next week look to be somewhere in the 60s to near
70F.

Forecast confidence does decrease pretty quickly next week. Most
models show a complex (or simply messy) pattern across most of the
western CONUS. The dominant features will be a couple of strong
shortwaves/closed lows across the Pacific Northwest and the
northern Great Plains, with a couple weaker shortwaves associated
with the subtropical jet. The general pattern supports warm and
dry conditions, though there could be a couple periods of
cooler/cloudier weather based on the track of those. There are
signs that the subtropical jet becomes more active by next
weekend... but it`s difficult to translate that into an actual
forecast at this time. We`ll let this current weekend pass by
before worrying too much about it.

&&

.AVIATION /12Z TAFS through 12Z Sunday/...
Issued at 342 AM MDT Sat Oct 24 2026

Northerly winds have held on through the majority of the overnight
hours at KDEN/KAPA, with KBJC mainly staying light and variable.
We are still anticipating another northerly push later this
morning, with winds starting to increase around 13Z before a more
defined frontal push around 15Z. Could see some 20-25kt gusts with
the front. Wind speeds should start to diminish by the early
afternoon and gradually turn to the east to southeast through the
evening and overnight hours across all the TAF sites.

The main impacts today will be from the gradual lowering of cloud
decks through the afternoon as the lower levels become saturated
behind the front. While there continue to be inconsistencies
amongst guidance this morning, there is a clear trend that shows
that around 21Z-22Z is when we should expect broken decks to lower
to around 5,000-6,000 feet AGL. There has been a slight push back
to shower potential timing, with the better chances looking to be
after 22Z-23Z at KDEN, slightly sooner at KBJC/KAPA. Ceilings are
expected to lower with any showers that pass along with a
reduction in visibility down to 4-5SM with showers as well. We
will likely see periods of MVFR conditions through the evening,
with a nonzero chance we see a brief period of IFR, before we
start to see some scattering around 9Z when we see some more
persistent southeasterly winds.

A cyclone is expected to develop Sunday morning that will lead to
some uncertainties in wind directions for the afternoon, but that
will primarily be for the next TAF period.

&&

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

&&

$$

DISCUSSION...Hiris
AVIATION...9