695
FXUS65 KBOU 221824
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1224 PM MDT Mon Jun 22 2026

.KEY MESSAGES...

- Strong to severe storms expected for the plains this afternoon,
  producing large/very large hail, gusty winds, and possibly a
  weak landspout.

- Strong/severe t-storms to become more numerous Tue-Wed, with
  increasing potential for impacts to I-25 corridor and localized
  flash flooding. Temperatures to remain slightly below normal.

- Elevated to locally critical fire weather conditions in the
  mountains most afternoons, increasing in severity this weekend
  under building heat and strengthening winds.

- Drier and considerably hotter for the lower elevations starting
  Friday.

&&

.DISCUSSION /Through Sunday/...
Issued at 1220 AM MDT Mon Jun 22 2026

The last of the showers have dissipated, giving way to steady
clearing, although some low stratus and fog may creep into our
northeast plains before sunrise. A warm, moist and unstable
airmass remains in place today, most pronounced over the plains
with the dryline progged to nudge slightly farther west. A Denver
cyclone looks to develop early in the day and reinforce easterly
flow, which would help limit drying from daytime mixing which some
guidance remains rather bullish about. Bulk shear also appears
more favorable this afternoon for organized convection in the
plains, with values exceeding 45-50 kts. All of the lower
elevations may see thunderstorms this afternoon, although the
strongest storms capable of producing very large hail should
largely be focused east of the I-25 corridor within SPC`s Slight
Risk area. Initial convection may be helped along by the DCVZ, but
additional development will be possible through the afternoon
driven by established outflow boundaries. As for temperatures,
they`ll hold steady for the lower elevations under the easterly
flow regime, with the mountains seeing moderate warming given
rising heights.

A cold front early Tuesday will bring milder conditions to the
lower elevations, together with a renewed influx of low-level
moisture as lee cyclogenesis promotes strengthening of upslope
flow into the Front Range. Unsurprisingly, this will serve to
increase PW values into the 1-1.25" range across the lower
elevations. Combined with ample instability and favorable shear,
the environment will favor development of supercells with large
hail in the afternoon, and a widespread severe weather threat to
include the urban corridor. Meanwhile, much drier conditions will
be present in our mountains, where an opposite pattern of dry
westerly flow may promote critical fire weather conditions in the
afternoon.

Little changes on Wednesday, with the lower elevations holding
onto abundant moisture, instability and shear. Thus, expect
continued thunderstorm development in the afternoon, some of which
will become severe. Given the moisture availability and
successive days of convection, localized flash flooding will
become an increasing concern for the plains as the week
progresses. The severe weather threat looks to carry into Thursday
as well, before precipitation potential shifts to favoring our
high country on Friday as zonal flow increases ahead of a
developing trough over the West Coast.

Said trough looks to transition into a rather potent closed low
over the northern Rockies this weekend. The impacts are two-fold.
First, a considerable warming and drying pattern regionwide as
upper level ridging strengthens ahead of the trough, quickly
returning temperatures to above normal values and potentially the
hottest of the year so far come Saturday. Second, robust mid-level
southwest flow over the Four Corners region will promote a notable
increase in wind speeds, particularly for the high country,
lending increased confidence to a period of highly critical fire
weather conditions this weekend.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1211 PM MDT Mon Jun 22 2026

VFR conditions are expected throughout the forecast period. The
Denver Cyclone moved directly over KDEN between 15z and 17z this
morning. TDEN shows that the cyclone is now located a few miles to
the east of KDEN. As a result, winds have now shifted to NNW
across the entire KDEN airport property.

TSRA development is still on track for this afternoon with KAPA
having the highest chance. ACARS soundings show a cap still in a
place, so have pushed TSRA chances back to start at 19z at KAPA
and 20z at KBJC and KDEN. All three terminals have the chance to
experience gusty outflow winds this afternoon of about 25 to 30
kts from thunderstorms as they move to the east.

By this evening, winds will stay elevated with gusts as high as 25
kts given the continued outflow enhanced winds especially at KDEN
and KAPA. At KBJC, NNW winds should stay around 10 kts for most
of the night after about 05z. A front will push through from north
to south for all three terminals between 13z and 15z tomorrow
morning with gusty winds from the north. By tomorrow afternoon,
winds should settle into a more NE direction. Showers and
thunderstorms will likely be possible especially at KDEN and KAPA
tomorrow afternoon with the threat for gusty outflow winds once
again, but there is low confidence in exact placement of
thunderstorms at this time.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 8 PM MDT Tuesday for COZ212-213-
217.

&&

$$

DISCUSSION...BRQ
AVIATION...MV

NWS BOU Office Area Forecast Discussion