401
FXUS65 KBOU 281135
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
535 AM MDT Thu May 28 2026

.KEY MESSAGES...

- Thursday will bring scattered showers and thunderstorms over the
  far northeast plains and in and near the foothills and I-25
  corridor. Stronger storms could produce some hail.

- Thunderstorm chances will increase Friday through Saturday,
  across the plains, with a chance of severe thunderstorms
  especially on Saturday.

- Afternoon showers and thunderstorms will be possible through the
  long-term forecast period with near-normal temperatures
  expected.


&&

.DISCUSSION /Through Wednesday/...
Issued at 250 AM MDT Thu May 28 2026

A few spots to the south and east of Denver have seen some
mist/fog development over the past couple of hours. A few showers
are also noted over far northeastern Colorado this morning, with
little across the Denver metro and most of the high country.
There`s still some uncertainty regarding any advection/development
of stratus/mist/fog towards the I-25 corridor through the mid-
morning hours, but most guidance isn`t keen on moving that too far
to the northwest.

The overall synoptic pattern today will not change significantly
from yesterday, as the two main players - the weak wave off in the
Central Great Plains, and the cutoff low over central California -
won`t move much over the next 12-24 hours. The most notable change
will be temperatures returning to the mid 70s across the I-25
corridor as weak ridging tries to build across Colorado, but the
plains should remain fairly cool due to the more expansive cloud
cover. With dew points still in the upper 40s to low 50s this
afternoon, MLCAPE values are expected to increase to around
1000-1500 J/kg across the lower foothills and I-25 corridor... but
will that be enough for storms? Those odds are relatively high
(60-70%) across the Front Range. While the HREF is also bullish on
the potential across the Denver metro, forecast soundings also
have a ~50mb isothermal layer centered around 650mb, which may
serve as just enough of a cap to limit any convective activity
this afternoon. If we do manage a storm or two across the Denver
metro, some hail would be possible given the instability and
meager shear.

Friday`s setup is a bit more intriguing as the closed low over
California shunts off to the east and transitions into an open
wave. While this looks to arrive a bit too late for any meaningful
lift here, a more subtle wave does track across the region during
the afternoon hours. Combined with surface convergence from a
likely DCVZ setup, that should be enough for at least isolated to
widely scattered thunderstorms during the afternoon hours. Surface
moisture does look a bit more limited compared to today, but
steepening lapse rates and increased DCAPE would at least favor
a marginal wind threat... especially north of I-70 and east of
I-25 where there`s better confidence in sufficient low-level
moisture.

The shortwave finally should swing across Colorado sometime
Saturday morning or early Saturday afternoon. While that will
increase the mid-level flow (and deep layer shear magnitudes), it
should also scour out a lot of the lingering boundary layer
moisture. Just based on the timing of the wave, the best chance at
seeing additional storms would be across far northeastern
Colorado. A few strong/severe storms would be possible yet again
though the overall pattern would favor areas to the north and east
of our CWA.

Forecast uncertainty increases by this weekend into next week.
The Friday/Saturday shortwave is forecast to lift almost due north
over the weekend, eventually attempting to phase with another
northern stream shortwave. Most of the deterministic guidance
eventually closes off the 500mb low once again, which then makes
no real effort to move in any particular direction. That leaves
most of the region in a weak southwesterly flow regime most of
next week. There`s less confidence in how much
moisture/instability we`ll see on any given day, but there should
be at least a few showers and storms each afternoon across the
Front Range into the eastern plains. Temperatures should also
slowly warm during the period with highs in the upper 70s to mid
80s.

&&

.AVIATION /12Z TAFS through 12Z Friday/...
Issued at 530 AM MDT Thu May 28 2026

VFR conditions are anticipated through the TAF period. There`s
been some FG/BR along with LIFR cigs well to the northeast and
southeast of DEN out on the plains. Nighttime microphysics RGBs
suggest that this has made it into southeastern Arapahoe county,
but given that winds are out of the SSW at DEN/APA it seems
unlikely this will make much more of a westward progression before
burning off later this morning. Still left a prevailing FEW002 for
a couple hours but chances of impacts at any of the terminals
still looks low (

NWS BOU Office Area Forecast Discussion