638 
FXUS65 KBOU 112016
AFDBOU

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

.KEY MESSAGES...

- Very warm today with only isolated high based showers/virga 
  late this afternoon and evening.

- 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 /18Z TAFS through 18Z Saturday/...
Issued at 1206 PM MDT Fri Sep 11 2026

VFR expected through the TAF period. Winds over the region are 
currently light (<10KT) and NW/N, with the exception of a channel of 
stronger downsloping WNW winds near KBJC occasionally gusting up to 
20KT. We expect northwesterly flow to prevail this afternoon through 
sunset (01Z-02Z). There is a chance for high-based showers to take 
shape late this afternoon although coverage is expected to be 
sparse. Nevertheless, dry microbursts and outflows could lead to 
erratic winds gusting up to 35KT near the showers. 

Winds tonight are a bit uncertain although there will likely be a 
return to SW/S drainage flow by 04Z. A cold frontal passage will 
bring a northerly wind shift ~10Z. 

&&

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

&&

$$

DISCUSSION...9
AVIATION...AA