412
FXUS65 KBOU 181751
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1151 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 /18Z TAFS through 18Z Friday/...
Issued at 1150 AM MDT Thu Jun 18 2026

VFR conditions will persist through the TAF period. Denver cyclone
developed this morning southwest of KDEN, and is now beginning to
shear eastward. Thus, light and VRB winds are now expected through
about 21Z. Then, a more diurnal E or NE wind is expected as the
cyclone is likely to transition into a shear zone south of the
Denver TAF sites. There is some uncertainty to the exact evolution
of course, but overall winds should remain 10 kts or less through
about 02Z. After 02-03Z, winds are expected to turn SE-S at KDEN
and KAPA and should be somewhat enhanced with sustained speeds
near 15 kts. Pressure patterns indicate those winds should then
weaken and transition more to the W-NW 11Z-15Z Friday, before
strengthening from the N-NE to around 12 kts behind a frontal
surge.

&&

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

&&

$$

DISCUSSION...MAI
AVIATION...20

NWS BOU Office Area Forecast Discussion