165
FXUS65 KBOU 120551
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1151 PM MDT Fri Sep 11 2026

.KEY MESSAGES...

- Slight increase in shower/storm coverage this weekend. Cooler
  Saturday, then warmer Sunday.

- Unsettled pattern next week, with multiple cold fronts expected
  to bring a few more noticeable cooldowns.

&&

.DISCUSSION /Through Friday/...
Issued at 1245 PM MDT Fri Sep 11 2026

This morning`s wave cloud kept some heat relief in place for the
northern corridor for the first half of the day. Now that the
cloud has dissipated, temperatures are quickly heating, with KLMO
seeing an eight degree warming in the past hour alone.
Temperatures were adjusted slightly to account for the cooler
morning, but we are still expecting a hot day across the lower
elevations due to downsloping winds and a slight warming in
temperatures aloft. Water vapor imagery shows moisture has
slightly increased in the westerly flow aloft through the morning.
We still expect some isolated high-based showers to develop this
afternoon over the higher elevations, with some virga showers
expected to bring gusty outflows to the lower elevations. We may
manage to squeeze a few sprinkles out of some of them, but mostly
just expect 30-40 mph winds as virga passes over for areas east of
the mountains.

A cold front is expected late tonight/early Saturday morning that
will bring some gusty northerly winds across the plains and
cooler temperatures for Saturday. A slight increase in moisture
is expected with the front as well. Afternoon showers and a few
storms will be possible, with the best chances being over the
northern mountains where instability will be greatest, but can`t
rule out some holding together long enough to push off the higher
elevations. Have added a mention of at least slight chance for
PoPs to the forecast across the northern plains and areas along
the Palmer Divide.

Sunday is still on track to be the hottest day of the week in
between cold fronts. While the NBM seems to have a warm bias, most
guidance does show afternoon highs in the low to mid 90s, so
afternoon highs were trimmed back slightly to be more in line with
the majority of guidance. Either way, it will still be hot for the
second week of September. There will be some better instability
in place across the northeast plains that if tapped into, could
allow for some stronger to severe storms in the afternoon/evening.

Not much has changed in the long term forecast today, with the
northern tier still expected to remain active over the next week.
A few cold fronts are still progged to bring a few more cooldowns
through the week, and afternoon showers and storms will be
possible each afternoon.

&&

.AVIATION /06Z TAFS through 06Z Sunday/...
Issued at 1149 PM MDT Fri Sep 11 2026

Weak prefrontal wind shift will bring VRB winds in the very short
term, then a cold front is scheduled to arrive by 08Z at KDEN
with a push of gusty north-northeast winds to around 20 kts.
Front will make it to KAPA by ~09Z, then winds should gradually
weaken and turn more northeast (more VRB at KBJC and KAPA), before
taking on a more easterly component by 15Z-18Z.

Another round of virga showers will be possible Saturday
afternoon, likely starting 21Z-22Z. Although conditions look
slightly less favorable than Friday, a few microbursts with gusty
winds up to 30KT cannot be ruled out, particularly near KAPA.
Otherwise, winds will gradually turn more SE-S but could be gusty
to ~20 kts due to outflows from showers on the Palmer Divide.
Winds eventually return to fairly normal S-SW by 05Z-06Z Sunday.

&&

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

&&

$$

DISCUSSION...9
AVIATION...20

NWS BOU Office Area Forecast Discussion