130
FXUS65 KBOU 042346
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
546 PM MDT Sun Oct 4 2026

.KEY MESSAGES...

- Dry and unseasonably warm through at least Saturday, with
  record/near record warmth on Monday.

- Isolated showers possible (15-30% chance) most afternoons for
  the higher elevations, highest Tue. Precipitation, if any, will
  be highly localized.

&&

.DISCUSSION /Through Sunday/...
Issued at 1200 PM MDT Sun Oct 4 2026

A ridge-dominated pattern will result in an uncharacteristically
warm week through at least Saturday, featuring departures from
normal of up to 15-20 degrees across the lowlands both Monday and
Tuesday. Today, a southerly and easterly low-level post-frontal flow
pattern together with the more western ridge axis placement will
see us "only" climb into the upper 70`s to lower 80`s in the
plains. A modest amount of mid-level moisture trapped beneath the
ridge may support an isolated shower this afternoon in and around
Park County, but given the lack of forcing, any precipitation
would be light.

The ridge nudges eastward Monday, with the return of subsident
flow and a light downslope wind component pushing temperatures to
near daily records for many. It`s probable (>75% chance) that we
will register a few 90F+ readings across portions of the urban
corridor and South Platte River Valley. Once again, a spotty light
afternoon shower can`t be ruled out for parts of the high country
with lingering moisture around.

Come Tuesday we`ll see a slight relaxation of the ridge, with
height falls leading to modest cooling aloft and thus marginally
unstable conditions in the high country. This should allow for a
minor uptick in afternoon showers over the mountains, and perhaps
a weak thunderstorm or two. Elsewhere, moisture will be much too
limited to support any precipitation, although a little more cloud
cover can be expected. With surface winds taking on a more
upslope component, temperatures look to cool a couple of degrees
over the plains/urban corridor, but will remain plenty warm.

General flattening of the ridge Wednesday through Saturday may
allow for a few degrees of additional cooling, however ensembles
remain locked-in on the continuation of well above normal
temperatures. It appears we`ll hold on to sufficient mid-level
moisture to support slight chances (10-25%) of an afternoon shower
in the high country essentially each day under a more westerly
flow pattern.

There is broad agreement among both deterministic and ensemble
guidance in the development of longwave troughing across the
Intermountain West over the weekend, with a resultant pattern
change for Colorado come Sunday or Monday as said trough pushes
east. Forecast uncertainty skyrockets starting Sunday, with
continued variability in trough amplitude and speed among the
range of available guidance. Cluster analysis using the 10/4 0Z
guidance favors the slower solutions by roughly 2:1. Whatever the
case, run-to-run trends suggest a rising potential for widespread
precipitation in the October 11-13 period, accompanied by a
notable cooldown. As is typical with these flow patterns, impacts
would be favored earlier for our mountains versus the lower
elevations, so the current forecast does introduce higher PoPs for
the high country beginning Sunday.

&&

.AVIATION /00Z TAFS through 00Z Tuesday/...
Issued at 533 PM MDT Sun Oct 4 2026

VFR conditions are expected through this TAF package. Easterly
winds are currently making their way through DIA with speeds
around 12kts. A boundary with stronger southerly winds behind it
is currently moving north/northwest towards KDEN and KAPA. This
boundary is expected to move into KAPA around 01Z and KDEN around
01Z to 02Z. Winds behind this boundary will be 12 to 15 kts, with
occasional gusts around 20kts. These breezier winds will continue
through 05Z/06Z, before winds turn more to the southwest and
begin to weaken. Overnight, expect drainage winds around 7kts to
12kts. Tomorrow morning we`ll see a period of light and variable
winds again before they turn more to the E/NE. At KBJC, winds will
generally be light with periods of variable winds through the
next 24 hours.

&&

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

&&

$$

DISCUSSION...BRQ
AVIATION...AP

NWS BOU Office Area Forecast Discussion