837 
FXUS65 KBOU 111808
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1208 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 Thursday/...
Issued at 231 AM MDT Fri Sep 11 2026

Zonal flow aloft will strengthen today, bringing a stronger
downslope component and thus a bit more warming. We expect highs 
to reach 90F or more over most of the plains and I-25 Corridor. 
To offset that, there is some mid/upper level moisture evident on 
satellite and radar now reaching northern Utah. This will continue
to push east today, resulting in enough for scattered virga,
isolated high based showers, and even a lone weak storm. The main
threat of any light precipitation would be over the northern 
mountains this afternoon, spreading to the northern plains this 
evening, but even there coverage would be sparse. Any high based 
showers/virga would support gusty outflow winds to 40 mph given 
increasing environmental flow and DCAPE increasing to 800-1200 
J/kg. 

For tonight, a cold front pushes south across the High Plains and
through northeast Colorado late tonight into early Saturday
morning. This will lead to cooler temperatures (near normal) for
Saturday. While moisture levels increase slightly, considerable
uncertainty exists for afternoon and evening shower/storm coverage
due to thermal profiles. For the most part, we don't think we'll
reach convective temps over the plains but still can't rule out
a few late day showers and storms spilling eastward from the
higher terrain due to mid level instability and moisture. 

Sunday will likely feature a return to much above normal
temperatures. MOS guidance suggest highs pushing into the mid 90s
for metro Denver and the I-25 Urban Corridor. That may be a bit
aggressive as there is some guidance (not surprisingly) slowing 
the redevelopment of lee troughing and erosion of low level
moisture. The record for Denver on the 13th is 96F set in 2018, 
1990, and 1895, but at this point it appears we'll most likely 
stay a couple degrees shy of that. With regard to convection, 
isolated showers and storms will be high based and relatively 
weak. However, if a storm or two can break the cap over the 
northeast plains they could certainly tap into higher MLCAPE and 
become severe. 

As discussed yesterday, the cooldown for Monday appears to be
tempered as the next cold front/upper trough has been delayed 
slightly. However, there is still high confidence in more 
significant cooling for Tuesday behind a moderately strong early 
(meteorological) autumn cold front. While daily uncertainties 
exist about the degree of cooling, there is modest agreement we'll
settle into highs in the 70s (and 30-40% chance of 60s) for the 
plains and I-25 Corridor. A brief warmup is possible for 
Wednesday before yet another front arrives Thursday. Ensembles are
in decent agreement holding a plume of mid/upper level moisture 
and higher than normal climatological precipitable water over us.
Thus, we should have daily chances of showers and storms most of 
the days this upcoming week. 

&&

.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...20
AVIATION...AA