050
FXUS65 KBOU 080527
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1127 PM MDT Mon Sep 7 2026

.KEY MESSAGES...

- Slightly cooler Tuesday into Wednesday with precipitation
  chances shifting mainly to areas south of I-70.

- Hotter and drier conditions Thursday and Friday.

- Return to more unsettled pattern and cooler weather favored for
  Sunday into Monday.

&&

.DISCUSSION /Through Monday/...
Issued at 1153 AM MDT Mon Sep 7 2026

Cloud cover made for a mild morning today, and has also slowed the
diurnal warming somewhat. ACARS soundings show abundant moisture
still in place (PW ~1" currently), and this should only increase
as the day progresses. Instability, which is a notch lower than
yesterday, will likely be maximized within the zone of southerly
flow south and east of the DCVZ. That said, the axis of better
shear is not particularly coincident, being shifted farther north
over the I-76 corridor where flow aloft will be stronger given
the approaching trough and jet. This makes it difficult to
pinpoint one specific area of greater coverage for afternoon
showers and thunderstorms. In any case, scattered showers look to
develop mid-afternoon over the urban corridor with potential for isolated
and mostly weak thunderstorms. The environment would support some
strengthening into the eastern plains where a few storms could be
strong to marginally severe later this afternoon and evening.
Temperatures will trend down for most areas given increased cloud
cover and upslope flow to the north of the DCVZ, with the warmest
temperatures focused over our southeast plains.

The upper-level trough will traverse the northern CONUS Tuesday,
pushing a weak cold front through the plains and lowering
temperatures 3-8 degrees for most areas. This will also lead to
more stable conditions and erosion of moisture across the northern
half of the forecast area, reducing precipitation chances
considerably. Areas roughly along and south of I-70, where better
instability, shear and PW will overlap, will remain favored for
afternoon convection and some locally heavy rain.

Drier westerly flow will settle into the region Wednesday as a
zonal pattern takes hold, potentially making Wednesday the coolest
day of the week with highs in the low/mid 80`s (only Sunday could
challenge that). Most will stay dry, though a chance of an
afternoon shower or thunderstorm will linger for Elbert and
Lincoln Counties. Those chances evaporate come Thursday as
moisture aloft decreases further. Temperatures look to rebound
back to above-normal values. Expect little change in those
conditions into Friday.

Forecast confidence lowers over the course of the weekend as models
begin to diverge in their treatment of an amplifying trough over
the PacNW. Most hint a subtle shortwave embedded within zonal flow
on Saturday and an associated weak cold front bringing initially
cooler temperatures and a return of precipitation chances. The
more significant cooldown however will likely wait until either
Sunday or Monday, depending on the timing of the stronger front
as the deeper trough approaches and lifts through the Northern
Rockies. Flow aloft will shift back to the southwest starting
Sunday with a strengthening jet in the mix as well. As such, we
should see a better window for a return to unsettled weather and
potentially some stronger thunderstorms and locally heavy rain,
but of course all of those details remain quite fuzzy.

&&

.AVIATION /06Z TAFS through 06Z Wednesday/...
Issued at 1122 PM MDT Mon Sep 7 2026

A weak boundary was moving across with a wind shift to the NE. By
07Z winds will become more light and variable and remain so
overnight. On Tue, winds will become ENE by 16z and then ESE by
19z. There will be a 20-30% chc of tstms by 21z, with the best
chance at APA with lower chances at BJC and DIA. For now will keep
in a prob30 between 21z and 01z. By 01z tstm chances should end
with winds becoming SE.

&&

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

&&

$$

DISCUSSION...BRQ
AVIATION...RPK

NWS BOU Office Area Forecast Discussion