733
FXUS65 KBOU 171113
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
513 AM MDT Wed Jun 17 2026

.KEY MESSAGES...

- Warm this week, with heat peaking Wednesday. Portions of the
  plains could see afternoon highs in the low to mid 90s.

- Elevated to critical fire weather conditions possible each day
  this week, with widespread critical fire weather conditions
  likely for the mountains and valleys on Wednesday.

- More active weather may return by the weekend into early next
  week.


&&

.DISCUSSION /Through Tuesday/...
Issued at 229 AM MDT Wed Jun 17 2026

Hot and mostly dry conditions expected through the weekend as an
upper level ridge continues to dominate the weather pattern. Today,
breezy winds will bring critical fire weather conditions to the
mountains and valleys where a Red Flag Warning will be in effect in
the afternoon. Northwest flow aloft will strengthen, with a 45-55 kt
jet over Colorado. This will allow winds to gust up to 50 mph across
the mountains, with localized higher gusts possible.

For the lower elevations, downsloping winds will aid in
compressional heating and allow temperatures to possibly reach up to
the mid-90s by the afternoon. Winds gusting up to 25-35 mph (and
possibly higher for areas off the Cheyenne Ridge) possible
throughout the day. However, hi-res guidance does have a weak cold
front moving through the plains in the early morning, which would
keep weaker northeast winds in place. As of right now, models have
the front washing out, with downsloping winds returning by the
afternoon. However, despite most models not resolving it, downslope
winds usually do not materialize after a frontal passage. If we do
not mix out by the afternoon, temperatures would not reach their
forecasted highs. For this reason, have slightly lowered max
temperatures for the plains. We will likely not reach Heat Advisory
criteria, however guidance still has areas along the I-25 Corridor
(including the Denver metro) in a category 2 for Heat Risk. This
correlates to a moderate risk for those who are sensitive to
heat. Those who are vulnerable to heat should take necessary
precautions today.

A stronger cold front is progged to trek across Colorado Wednesday
evening. This will bring cooler temperatures for Thursday, with
forecasted highs in the mid-80s for the plains. However, this mild
reprieve in hot temperatures will be short lived, as the upper
level ridge is progged to shift east and the axis of the mid-level
thermal ridge situates itself over Colorado. Temperatures will
once again rise to the low 90s across the plains on Friday.

For the weekend, ensemble guidance has the upper level ridge flatten
due to an incoming shortwave trough. Compressional heating on
Saturday could allow temperatures to reach to the upper 90s. Current
ensemble solutions range from 91-99 F, with a few showing 100 F.
Although it is important to note that the 00Z GEFS has trended
cooler. Will keep an eye to see if that trend continues. With the
arrival of the shortwave, precipitation chances increase, mainly for
the eastern plains. Sunday could see a few thunderstorms, however
best instability looks to be just east of the forecast area.
Guidance looks to keep temperatures near seasonal normals Sunday
through Tuesday, with additional precipitation chances in the
afternoons.

&&

.AVIATION /12Z TAFS through 12Z Thursday/...
Issued at 500 AM MDT Wed Jun 17 2026

VFR conditions expected through the TAF period. Winds currently
from the west at all terminals, with gusts up to 20 kts. Expect
this to continue for the next few hours before a weak cold front
arrives by 15-17Z. Behind the front, winds should transition to a
more northerly/northeasterly component. Most guidance has
downslope northwest winds returning in the afternoon, however
there is still some uncertainty if that will happen. Rather, we
could have winds stay northeast, like it usually does in this
scenario. Due to low confidence and lack of model agreement, have
kept the northwest winds in the TAF for now. If we are able to mix
out, expect gusts up to 30-35 kts at times.

A stronger cold front will likely arrive by 02-04Z this evening,
with northeast winds gusting up to 25-30 kts. Winds should
gradually weaken by 06Z before transitioning to southeast
overnight.

&&

.FIRE WEATHER...
Issued at 229 AM MDT Wed Jun 17 2026

Critical fire weather conditions expected for the mountains and high
valleys today. Winds gusting up to 50 mph, with localized stronger
gusts up to 60-65 mph is possible. With downsloping winds possible
for the lower elevations, there could be localized elevated fire
weather conditions for the foothills and adjacent plains. However,
fuels have been deemed not critical, so no fire weather highlights
are expected. Another area of potential concern today are the far
northeastern plains. Winds off the Cheyenne Ridge could bring gusts
up to 35 mph. However, with a cold front arriving, RH values should
stay above 15%.

Elevated fire weather conditions possible Thursday and Friday for
the mountains and high valleys due to continued low RH values.
However, winds should be weaker, with speeds generally under 25 mph.
Gusts of 30-35 mph could occur, however they should be short in
duration. If guidance changes, may need to have highlights out.

With the upper level ridge flattening on Saturday, cross-barrier
flow is expected to increase, with winds becoming stronger and more
widespread across the mountains and valleys. Relative humidity
values will continue to range between 11-15% which will bring about
another round of critical fire weather conditions.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon today to 8 PM MDT this evening for
COZ211>214-217-218.

&&

$$

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

NWS BOU Office Area Forecast Discussion