203
FXUS65 KBOU 180821
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
221 AM MDT Thu Jun 18 2026

.KEY MESSAGES...

- Elevated fire weather conditions in the mountains and valleys
  today and Friday with critical conditions expected on Saturday.

- Strong to severe storms possible across the eastern plains on
  Saturday.

- Scattered coverage of showers and storms on Sunday and Monday.


&&

.DISCUSSION /Through Wednesday/...
Issued at 218 AM MDT Thu Jun 18 2026

Relatively quiet weather expected today as northwest flow aloft
decreases as the upper level ridge begins shifting east. With the
passage of the cold front, temperatures today should be cooler
than yesterday, with the plains reaching up to the mid-upper 80s
by the afternoon. Elevated fire weather conditions are possible
for the mountains and high valleys. However, due to the expected
marginal conditions (winds generally at or under 25 mph) have
opted out of any highlights. There could be gusts up to 30-35 mph,
particularly across the southern Front Range mountains, but they
should be short in duration.

Temperatures will begin warming again on Friday, with highs in the
upper 80s, and possibly low 90s for portions of the eastern plains.
Another round of elevated fire weather conditions is possible for
the mountains and North Park. However, with relatively weak flow
aloft, winds should remain under 25 mph. For the plains, with some
mid-level moisture advecting into the region, there could be an
isolated shower/weak thunderstorm, mainly near the Palmer Divide
area in the late afternoon.

Saturday is looking to be an active day, with increasing fire
weather concerns over the mountains and strong-to-severe
thunderstorms for the plains. The upper level ridge will flatten due
to an incoming shortwave trough. This will allow winds across the
high terrain to strengthen, with westerly winds gusting up to 45 mph
throughout the afternoon. With the expected low relative humidity
values, have issued a Fire Weather Watch for the mountains and high
valleys. However, it is important to note that the northern Front
Range mountains, Park Range, and North Park may not see RH values
down to 15% due to the incoming system advecting moisture into the
region. Will be watching closely on the evolution of the shortwave,
as an earlier arrival of the system could keep those areas out of
fire weather highlights for Saturday.

For the plains, temperatures should once again warm up to the 90s by
the afternoon. With the arrival of the shortwave, showers and
thunderstorms are possible, with strong to severe storms becoming
increasingly likely for our eastern plains where a dry line will
set up. Modeled Skew-T soundings how MLCAPE up to 3000 J/kg, with
decent 0-6 Km bulk shear promoting good updrafts in storms. SPC
has portions of our plains in a Marginal (1/5) and Slight (2/5)
risk, which seems reasonable at this time.

Guidance continues to favor multiple shortwaves passing through
towards the beginning of next week. This will provide daily
chances of showers and thunderstorms throughout the week, mainly
for the foothills and plains. Seasonal temperatures are expected
for the first half of the week, with highs in the low-to-mid 80s.


&&

.AVIATION /06Z TAFS through 06Z Friday/...
Issued at 1117 PM MDT Wed Jun 17 2026

VFR conditions expected through the TAF period. With the passage
of the cold front, northeast winds have been gusting up to 35 kts.
Expect winds to gradually weaken in the next hour before speeds
decrease to less than 15-18 kts tonight. Winds will have a more
southerly component in drainage flow overnight, with DEN and APA
being closer to 160-180.

For Thursday, a cyclone is expected to develop, which will likely
keep APA east/southeast throughout the day and BJC more northeast.
Some uncertainty with winds at DEN, however generally expect them
to vary between southeast to northeast as the cyclone moves out of
the area. Speeds should remain under 15 kts.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Saturday afternoon through Saturday
evening for COZ211>214-217-218.

&&

$$

DISCUSSION...MAI
AVIATION...MAI

NWS BOU Office Area Forecast Discussion