170
FXUS65 KBOU 111118
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
518 AM MDT Mon May 11 2026

.KEY MESSAGES...

- Summerlike warmth and drier weather this week, with highs in the
  80s for the lower elevations.

- Warmest temperatures of the week (mid to upper 80s for the
  plains) on Wednesday and Thursday.

&&

.DISCUSSION /Through Sunday/...
Issued at 123 AM MDT Mon May 11 2026

Warm and mostly dry conditions are expected to dominate the weather
pattern through the end of the week as an upper level ridge of high
pressure builds over southwestern United States. Temperatures will
likely climb 10 to almost 20 degrees above normal each day, with
portions of the plains possibly reaching 90F by midweek.

Monday will be mostly quiet, with temperatures reaching up to the
mid-80s and relative humidity values dropping to the low teens
across the forecast area. Localized elevated to critical fire
weather conditions are possible, particularly for the
mountains/valleys where winds will be the strongest. The far
northeastern plains may briefly see elevated fire weather conditions
in the afternoon as well. However, winds should stay below 25 mph
across the plains throughout the day.

A cold front is expected to move through overnight Monday, with hi-
res guidance indicating isolated gusty winds of 30-40 mph behind it.
Despite this frontal passage, warm air advection will allow
temperatures to reach the mid-to-high 70s across the forecast area
by Tuesday afternoon. With mid-level moisture being advected into
the region and weak instability building, a few
showers/thunderstorms are possible for the Front Range.

Guidance continues to be in good agreement of heat peaking by
midweek, as the axis of the mid-level thermal ridge shifts east over
Colorado. The majority of the ECMWF ensemble members (29/50) do
indicate temperatures reaching 90F at KDEN. However, other ensemble
guidance and some new hi-res guidance do favor the `cooler` end of
solutions, with temperatures in the high 80s instead. With lingering
moisture in place, we could see another round of light rain showers
and isolated thunderstorms across the southern Front Range and
portions of the plains in the afternoon/evening.

Some uncertainty remains in the forecast Thursday through the
beginning of the weekend as models try to resolve an upper level
closed low trekking east from California. Most guidance keeps the
low north of Colorado, however there are inconsistencies between
model runs of the evolution of the low. It is interesting to note
that deterministic GFS and AIGFS have been consistent between the
last few runs of the closed low trekking across southern Colorado.
While it is most likely we remain mostly dry towards the weekend
with the low trekking north of Colorado like most guidance
indicates, a more southerly track of this system would bring more
showers/thunderstorms to the forecast area. Will continue to
monitor.

&&

.AVIATION /12Z TAFS through 12Z Tuesday/...
Issued at 518 AM MDT Mon May 11 2026

VFR conditions expected through the TAF period. Drainage flow will
give way to light and VRB winds for all terminals by mid-morning.
In the afternoon, there is some uncertainty in wind direction for
DEN and APA. Guidance indicates downslope northwesterly winds at
BJC by 22Z, but still unsure if they will make it all the way to
DEN (unlikely to make it to APA). If this does not materialize,
expect light (generally less than 8 kts) easterly winds instead.
Drainage flow will return by 03Z-04Z. Overnight tonight, a cold
front will pass through DEN and BJC by 10Z and APA by 11Z. A few
lower clouds may accompany the front, however no ceiling issues
are expected.

&&

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

&&

$$

DISCUSSION...MAI
AVIATION...MAI