860
FXUS65 KBOU 131903
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
103 PM MDT Wed May 13 2026

.KEY MESSAGES...

- Summerlike warmth through Friday with isolated high based
  showers and thunderstorms.

- Elevated to locally critical fire weather conditions each day
  through Friday.

- Shower and storm chances will increase this weekend into early
  next week. Trends have been wetter and cooler, especially by
  late Sunday and Monday.

&&

.DISCUSSION /Through Wednesday/...
Issued at 103 PM MDT Wed May 13 2026

Isolated high based showers and storms are attempting to develop,
but moisture so far is quite limited with MLCAPE less than 250
J/kg. However, mid level moisture is arriving from the southwest
in advance of an upper level disturbance, and that should support
further development of high based showers and isolated storms
into the evening hours. DCAPE is growing to near 1400 J/kg and
with LCLs near 20,000 ft MSL we expect strong, gusty outflow
winds/microbursts to be the main threat, lasting well into the
evening. Peak gusts of 40-45 mph expected with most of these, but
given above mentioned parameters an isolated severe gust to 60
mph is possible. A couple showers could linger well past midnight
in the mountains due to a weak shortwave passing through the
ridge.

For Thursday, the ridge axis continues to flatten as the weak
shortwave moves into the Central Plains. This will bring some
drying and stabilization, although the southern half of the
forecast area could still see enough moisture hold for isolated
high based convection. Weak cool advection occurs, but
temperatures will only be a degree or two lower than today and
near record levels (Record for Denver is 87 set in 2013).
Sufficient flow aloft and mixing means breezy conditions will
develop over the mountains and northern plains, resulting in
critical Red Flag conditions over the northern tier of the plains
where we`ve upgraded to a Red Flag Warning. Land managers
indicated fuel have greened up sufficiently in our mountain areas,
but remain locally critical in the foothills so will continue to
monitor.

Friday will be warm and mostly dry, although some return moisture
will support a few showers and storms over the foothills/Palmer
Divide area for the afternoon.

The weather is shifting toward a more active pattern as we head
through the weekend into early next week. For Saturday, there is a
chance low level moisture increases sufficiently over the plains
to support 500-1000 J/kg and thus a few stronger/isolated severe
storms, so something to watch over the next couple days. For
Sunday, shower and storm chances are expected to increase further
as an upper level trough drops through the Northern Rockies and
Great Basin. The trend has been for a deeper trough and potential
for higher shower/storm coverage and more meaningful precipitation
from Sunday afternoon into Monday. Temperatures will be turning
much cooler by late Sunday into Monday. While there is
considerable spread in the forecast temperatures from each
ensemble member, the 25th-75th percentiles suggest highs only in
the 50s by Monday. Cool and unsettled weather could last into the
middle of next week.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 1102 AM MDT Wed May 13 2026

VFR conditions will prevail for all terminals through the TAF
period. Winds over the next few hours will be rather variable,
generally favoring southeasterly directions but with lower
confidence for KAPA and KDEN given their proximity to a
convergence boundary. By 21-22Z, south to southwest winds will
become prevalent.

At around the same time, high-based (AOA ~120) convective -SHRA
or -TSRA will develop across the metro and push E/NE. With warm
and dry surface conditions, the environment will be conducive for
strong outflows with gusts to 40 kts in the vicinity of the
strongest showers/storms. TS coverage could be high enough to
warrant inclusion in TEMPO groups eventually, but will assess
trends through the morning prior to making such a change.

Expect robust drainage flow to prevail overnight with most of the
shower activity subsiding after 03-04Z, though some decaying
showers can`t be ruled out into the late evening hours.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 9 PM MDT Thursday for COZ238-242-
248-250-251.

&&

$$

DISCUSSION...20
AVIATION...BRQ

NWS BOU Office Area Forecast Discussion