432
FXUS65 KBOU 221017
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
417 AM MDT Sat Aug 22 2026

.KEY MESSAGES...

- Heat eases, along with an increase in shower and storm coverage
  this weekend.

- Highest coverage of showers and storms expected today, along
  with a few severe storms on the plains this afternoon and
  evening and then again Sunday.

- Gradual drying next week, but continued storm chances through
  at least Wednesday or Thursday. Slight cooling but temperatures
  still above normal.

&&

.DISCUSSION /Through Friday/...
Issued at 249 AM MDT Sat Aug 22 2026

A slight cooldown is expected today after Friday`s record breaking
heat. While temperatures are still expected to remain above
normal, we should only see highs range from the mid 80s to the low
90s across the lower elevations before afternoon showers and
storms bring some heat relief. Not much has changed in today`s
forecast, as we still expect today to bring this week`s best
chance for wetting rains as PWATs are expected to be around 150%
of normal. Instability will increase today, with high-res models
showing a wide range of values (600-3500 J/kg of MLCAPE). Despite
these models having inconsistent MLCAPE values, they are in
fairly good agreement that the best environment for severe storms
will be along a line from the Cheyenne Ridge southeastward across
the plains, just east of DIA. As storms are expected to remain
high-based as they move off the higher terrain, they will be
capable of producing gusty outflows, with a few strong to severe
gusts expected throughout the afternoon and evening as storms move
across the plains. With the above normal PWATs in place, we could
have a few localized heavier rains too. Additionally, mid-level
lapse rates will be sufficiently steep (8-9 C/km) to support an
isolated hail threat. 0-6 km shear will be marginal (~30 kts), but
enough to support potential for storm organization.

The upper-level ridge is still expected to flatten out on Sunday
and Monday as a shortwave tracks east out of the Pacific
Northwest. While moisture isn`t expected to be as robust as today,
PWATs are still expected to be around 120% to 130% of normal each
afternoon that will support afternoon showers and storms, with a
few strong to severe storms possible each afternoon, and above
normal temperatures persisting before a chance at sub 90 degree
highs returns Tuesday and Wednesday.

The latest ensembles keep above normal PWATs in place through the
week though a gradual drying is still expected. This will keep
at least isolated to scattered afternoon showers and storms
possible through the week. The upper-level ridge is then expected
to rebuild, bringing temperatures right back into the 90s across
the plains to end the work week.

&&

.AVIATION /06Z TAFS through 06Z Sunday/...
Issued at 1221 AM MDT Sat Aug 22 2026

An outflow from severe storms over northeastern Colorado has
pushed across KDEN/KBJC turning winds to the north. The boundary
as slowed down as it passed over KDEN airfield that might keep it
from reaching KAPA, but for now it has at least slowed it down
from what is in the current TAF. With the upslope winds, weak
showers are starting to develop around the TAF sites. Have
introduced a PROB30 at KDEN/KAPA until 8Z to account for any
gusty winds that may be produced if these can hold together before
winds can make their way back to drainage in the next few hours.
Expect some sort of southeast to south transition over the next
few hours at KDEN while drainage tries to reestablish.

Drainage winds are expected to turn around the clock and land to
the northeast across all TAF sites by early this afternoon
(17-18Z). Greater storm coverage is expected this afternoon
compared to yesterday, with storms expected to move off the higher
elevations between 20-22Z and continue through late tonight
(5-6Z). Gusty winds are expected with passing storms, with gusts
between 35-45 kts possible, but can`t rule out a severe storm
passing over or near the TAF sites. Storms are expected to be
high-based, with guidance showing CIG staying above 9,000 feet
AGL. Like today, can`t rule out an outflow or two making their way
across the TAF sites after storms have diminished that could
disrupt or delay drainage winds from taking hold.

&&

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

&&

$$

DISCUSSION...9
AVIATION...9

NWS BOU Office Area Forecast Discussion