662
FXUS65 KBOU 241849
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1249 PM MDT Mon Aug 24 2026

.KEY MESSAGES...

- Scattered afternoon and evening showers and storms through at
  least Thursday. A few storms could become severe, particularly
  for the eastern plains.

- Slightly cooler with near normal temperatures for Tuesday and
  Wednesday.

- Gradual drying and hotter temperatures by Friday and the
  weekend, but a few storms still possible.

&&

.DISCUSSION /Through Monday/...
Issued at 1249 PM MDT Mon Aug 24 2026

The airmass has dried a little since yesterday, with the main
drying observed in the low levels. That is resulting in less
instability, with MLCAPE less than 500 J/kg in all but the far
eastern plains. While lapse rates will still be conducive to
scattered showers and storms, they will be high based and capable
of producing gusty outflow winds to 40-55 mph as DCAPE grows to
1200-1400 J/kg over the plains and I-25 Corridor. There is still a
conditional threat of a couple severe storms over the northeast
plains this evening, as low level moisture is forecast to start
advecting westward from Nebraska. However, that airmass could be
more capped. If they develop or move southward from Nebraska,
then a threat of large hail and damaging winds would exist. The
SPC Slight Risk area looks reasonable there. Only an isolated
high wind gust threat would exist over the rest of the plains late
this afternoon and early evening.

A weak frontal boundary attempts to push southward across the
plains late tonight and Tuesday, with an uptick in low level
moisture. While some of this gets mixed out during peak heating
especially along the I-25 Corridor, instability and moisture
values are both forecast to increase from today. We expect
scattered showers and storms to develop over the mountains around
the noon hour, and then spread and intensify as they move eastward
into the higher instability airmass over the eastern plains. A
couple storms may become severe east of the I-25 Corridor where
instability grows to 1000-2000 J/kg as one heads east to the
eastern border.

For Wednesday, low level moisture is expected to increase further
and pool back closer to the Front Range and I-25 Corridor due to
persistent but light easterly flow behind an additional frontal
surge. While temperatures will be a little cooler (one day finally
near normal!), we do expect to build sufficient instability for
our highest chance of strong and potentially a couple severe
storms closer to the I-25 Corridor. Storms will also be capable of
locally heavy rainfall given the increase in low level moisture.

Thursday is still expected to see another round of scattered
showers and storms in the afternoon, but the ridge axis begins to
tilt toward the forecast area. We`ll still have sufficient
instability over the plains for a couple strong/severe storms, as
long as we can break the cap. The odds of storms decreases by
Friday as we see the ridge axis shifting across the forecast area,
with a drier and more capped airmass. There`s still uncertainty
about how fast we scour the eastern plains moisture, so we can`t
totally rule out a few storms. Temperatures will almost certainly
be warming up, with mid 90s the most likely outcome across the
plains by Friday as the ridge/thermal axis shifts overhead.

More uncertainty enters the picture for the weekend, but ensembles
do support more heat. We`ll also be getting into a little stronger
west/southwest component aloft, as a significant shortwave moves
east across the Northern Rockies. This would support increasing
breezes and an increase of elevated fire weather conditions for
the northern mountains. However, at the same time most ensemble
members keep mid/high level moisture streaming off the Central
Pacific, so humidity numbers might stay up sufficiently and also
be supportive of a few showers and storms. Saturday looks quite
hot again (mid 90s for the plains and I-25 Corridor), while
ensembles start to suggest some cooling by Sunday or Monday.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1159 AM MDT Mon Aug 24 2026

VFR conditons are expected to prevail through the TAF period. Winds
have made their northward turn and should stay there for the next
several hours. Recent ACARS soundings show the low-level inversion
dissipating, but we`re not seeing as much cumulus forming off the
foothills as we did at this time yesterday. The latest CAMs runs
have convection initiating in the area closer to 21Z over the Front
Range, and given both the timing of impacts yesterday and today`s
current conditions, we`ve opted to push back the TEMPO for KDEN to
22Z. Current observations show that we`re a little dryer today than
we were yesterday, and model soundings favor decent instability
around 21/22Z, so we should be in for more of a wind/outflow threat
than heavy precipitation. There is some uncertainty in when today`s
convection will move out of the area, so to account for any
lingering showers or outflows, we`ve kept a PROB30 in until 03Z.
Winds should then turn southwest towards drainage, and recent model
runs seem to have pulled back on the low cloud chances overnight. By
late morning (16-17Z) on Tuesday, winds should turn northward, and
another round of convection is expected again at roughly 21/22Z.

&&

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

&&

$$

DISCUSSION...20
AVIATION...AGS

NWS BOU Office Area Forecast Discussion