646
FXUS65 KBOU 081905
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
105 PM MDT Mon Jun 8 2026

.KEY MESSAGES...

- Strong to severe thunderstorms expected for the I-25 Corridor
  and eastern plains this afternoon. However, cooler temperatures
  may affect convective evolution.

- More heat ahead, with the hottest temperatures Tuesday. Highs
  generally in the lower to mid 90s across the I-25 Corridor, but
  just shy of 100 over the northeast plains.

- Widespread critical fire weather conditions expected (>90%
  confidence) in fuel-prone areas by Tuesday, potentially (60-70%
  chance) lasting into Wednesday.

- Brief heat relief expected Thursday, before a more substantial
  cooldown for the weekend.

&&

.DISCUSSION /Through Monday/...
Issued at 1238 PM MDT Mon Jun 8 2026

Strong to severe thunderstorms are expected this afternoon across
the I-25 Corridor and eastern plains, with supercells capable of
producing large to giant hail, damaging outflow winds, and a few
tornadoes. Strong southwest flow aloft is currently over Colorado,
with a surface low pressure located in southwestern Kansas,
allowing easterly winds to advect moisture into the plains
(dewpoint temperatures already reaching up to the 50s). MLCAPE
values are expected to reach up to 1500-2000 J/kg (better
instability east of Denver metro) this afternoon, with 0-6 Km bulk
shear up to 50 kts and mid-level lapse rates >8.0 dg C/Km. This
will support intense updrafts in supercells, and promote hail
sizes up to 2" and damaging outflow winds for the I-25 corridor.
Guidance is in good agreement of storms initiating between 1-3 PM
along the I-25 Corridor and trekking east through the afternoon.
However, current ACARS soundings still show a capped environment
due to early morning cloud cover. This could keep any severe
threat out of the metro early this afternoon. We will continue to
watch to see if the cap can erode in the next few hours.

As supercells travel east out of the metro this afternoon, they will
be entering an environment more favorable for 3"+ hail and a few
tornadoes, as evident in modeled soundings showing better
instability and curved hodographs. Areas along and around the I-70
corridor east of the metro have the best chance to see this, where
SPC has now upgraded us to an Enhanced risk (3/5) through this
evening. As storms continue east this evening, they should organize
into a line, where damaging outflow winds will be the main threat.
Expect storms to be completely out of the forecast area by 9 PM.

Hot temperatures return to the forecast on Tuesday as strong
southwest flow aloft promotes downsloping winds and thus
compressional heating. Highs are expected to be in the mid-90s, with
DIA having the chance to break the daily high record (Record: 95 in
2018; Forecast: 93). With widespread breezy winds and a dry airmass
over the region, elevated to critical fire weather conditions are
possible across the plains (See Fire Weather Discussion). Isolated
thunderstorms are possible Tuesday afternoon across the eastern
plains, however little precipitation is expected to reach the
ground, given LCLs up to 10K-11K ft AGL and fast storm motions.
However, we could have strong outflow wind gusts, given DCAPE values
expected to get up to 1500 J/kg. The best chance for the strongest
winds will be the far northeastern plains where SPC has put us in a
marginal risk (1/5) for severe thunderstorms.

A weak cold front overnight Tuesday, will slightly lower
temperatures for Wednesday, but still expect highs in the high 80s
to low 90s across the plains. A 500-mb jet will be over Colorado,
with cross barrier flow of 40-50 kts, resulting in breezy winds
across the high terrain. Wind prone areas along the I-25 corridor
will likely see some gusty winds throughout the day Wednesday, which
could bring another round of elevated to critical fire weather
conditions.

Zonal flow aloft is expected Thursday and into the weekend as
Colorado will be in between an upper level ridge in southern United
States and a closed low over northern U.S. and Canada. This will
result in relatively quiet conditions across the forecast area, with
temperatures generally between 80s to low 90s. Next chance for
precipitation looks to be Saturday ahead of an upper level trough.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1144 AM MDT Mon Jun 8 2026

Stratus clouds are starting to clear across the TAF sites with
KDEN the last to see them breaking up as the western flank remains
over the airfield, but should be seeing clearing skies within the
next hour. These will play a factor in what happens this
afternoon as they have kept temperatures quite modest underneath
their cover this morning. We are still expecting temps to warm
upon the clearing and we remain under potential for severe
thunderstorms to cross the TAF sites this afternoon, with KDEN
being upgraded to an enhanced threat by the SPC to include
potential for large hail, and in a level two intensity level
which signifies the environment will be capable of producing
destructive hail 3"+ in size. Both BJC and APA are just outside
the level two hatching, but still risk potential for 2"+ sized
hail with any storms that develop. With the delayed warming, we
may see a delay in convective initiation and timing until we
reach convective temps, therefore the PROB30 was continued rather
than upgrading to a TEMPO. The best timing for storms to impact
airports will be between 21-23Z, but we may still see some impacts
through 0Z, and anticipate there may be some gusty outflows that
we may need to contend with past that. We can expect CIG to drop
as low as 050 with passing storms, and heavy precipitation and
large hail will reduce VIS down to about 3SM.

Beyond the severe storms this afternoon, expecting winds to
transition to the south for the overnight hours before we see them
strengthen in magnitude for the majority of the day tomorrow,
starting by 15Z, with 25-35kt gusts expected through the
afternoon. Additionally, while we are thinking the best chances
for precip will be south and east of the TAF sites, but can`t rule
out high-based showers bringing some gusty and variable winds
across the TAF sites in the afternoon. Have introduced VCSH to
highlight this potential for now.

&&

.FIRE WEATHER...
Issued at 1238 PM MDT Mon Jun 8 2026

Elevated to critical fire weather conditions are expected Tuesday
and Wednesday across the plains. Winds could gust up to 30 to 40
mph, with relative humidity values dropping to single digits each
afternoon. Recent feedback about fuels status shows that
vegetation across the plains are susceptible to combustion, so
have opted in to upgrade the Fire Weather Watch to a Red Flag
Warning. Localized fire weather conditions remain possible on
Thursday and Friday due to expected low relative humidity values.
However, winds will be the limiting factor as guidance indicates
more localized nature of stronger winds.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 9 PM MDT Tuesday for COZ240>251.

&&

$$

DISCUSSION...MAI
AVIATION...9
FIRE WEATHER...MAI

NWS BOU Office Area Forecast Discussion