129
FXUS65 KBOU 012005
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
205 PM MDT Mon Jun 1 2026

.KEY MESSAGES...

- A chance for strong and severe thunderstorms this afternoon
  along the I-25 Corridor, with large hail, gusty winds, and a
  brief tornado possible.

- Severe storms will be possible again Tuesday afternoon, with
  locally heavy rain possible.

- Thunderstorm chances will continue on Wednesday with lower
  threat for severe storms, however, locally heavy rain will be
  possible.

- Trending warmer and drier by the end of the week.

&&

.DISCUSSION /Through Monday/...
Issued at 158 PM MDT Mon Jun 1 2026

The synoptic pattern shows a broad upper-level low is in place over
the Pacific Northwest, with a 80kt, southwest to northeast situated
upper-level jet residing across the Central Rockies on this Monday
morning. This is bringing southwesterly flow aloft across Colorado,
with fairly robust low-level moisture (50F dewpoints) advecting into
eastern Colorado via southeasterly upslope.

Latest East Meso-2 Day Cloud Phase shows cumulus clouds along the
Front Range Mountains are starting to show vertical growth early
this afternoon. These storms are expected to become more robust
within the next hour or two with potential for severe storms to
develop along the I-25 Corridor between the 1-2PM time frame, where
the SPC has the majority of our lower elevations in a Slight Risk
(2/5 threat level). Latest ACARS sounding shows MLCAPE values around
1000 J/kg, with only a few degrees of surface heating needed to
overcome a 700 mb inversion. Upslope flow to near 700 mb is also
visible on KFTG VAD Wind Profiler, with surface dewpoints ranging
from the upper-40s to mid-50s across the foothills and plains.
Expecting storms to initially be discrete in nature with large hail
(2-3") being the main threat, before progressing eastward where the
environment will be more conducive to a more linear storm mode, with
strong winds becoming the primary threat. While tornadoes are not
expected to be the main threat today, a brief tornado cannot be
ruled out where any low-level circulations can hold together. The
severe threat is expected to diminish from west to east, moving out
of metro Denver by 6PM and 8PM-9PM for the eastern plains. Hi-res
guidance has continued to show shower and non-severe thunderstorms
becoming reestablished behind the exiting severe threat, mainly
along the South Platte River Valley, by 11PM-12AM continuing to
around sunrise.

For Tuesday, flow aloft will transition to a more zonal pattern with
surface dewpoints expected to remain fairly robust once again.
MLCAPE values are not expected to be as strong as today, but values
between 500 to 1200 J/kg will be in place by the afternoon, with
conditions favorable for another day of severe storm potential
across the eastern plains. MUCAPE increasing to greater than 1500
J/kg mixed with steep mid-level lapse rates will support the
development of baseline severe hail size potential, with shear
weaker than today looking to keep the threat of anything larger than
2" limited and gusty outflows the most likely severe threat.
Expecting storms to initiate between 1PM to 3PM and coverage to be
far less than today, with the SPC having areas generally east of I-
25 in a Marginal risk (1/5 threat level).

Afternoon thunderstorms will be possible once again Wednesday, with
an isolated threat of some becoming severe, mainly for the eastern
plains. Temperatures are forecast to gradually increase through the
week, reaching for the 90s by Thursday as 700 mb flow warms by about
10C. Warmer and drier conditions are expected from Thursday onward,
with increasing elevated fire weather conditions expected as the
warmer and drier weather persists into the weekend, though with
greenup well underway and multiple chances for precip through
mid-week, any developing fire weather concerns will likely remain
limited and localized.


&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1158 AM MDT Mon Jun 1 2026

East to southeast winds have increased moisture across the area
and brought stratocumulus clouds at 3,500 to 5,000 feet. These
clouds will burn off soon as the airmass warms. This increase in
moisture will fuel thunderstorm development this afternoon
beginning around 19Z. Main time frame for a thunderstorm at DEN
will be 20Z to 23Z. Hail (possibly large), heavy rain, and wind
gusts to 50 knots will be possible under the stronger storms.
Models agree there should only be one round of thunderstorms this
afternoon, so by 22-00Z, expect storms to be east of DEN.

Low clouds will develop after midnight between 08Z and 10Z and
then linger most of Tuesday morning. Ceilings are expected to be
in the 1000 to 3000 foot range, with a slight chance (20%) of
ceilings under 1,000 feet. A Denver cyclone is expected to help
form the low clouds. Then mid morning winds become southeast. This
will end the threat of lower ceilings (~1000 feet) and slowly
erode the remaining low clouds. Another round of afternoon
thunderstorms is expected, beginning around 21Z. There`s a chance
the airmass is capped, with the best chance for this occurring
north of Denver.

&&

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

&&

$$

DISCUSSION...9
AVIATION...12