302
FXUS65 KBOU 060020
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
620 PM MDT Tue Aug 5 2025

.KEY MESSAGES...

- Critical fire weather conditions for mountains and high valleys
  through at least Friday.

- Hot and dry all areas through Friday, likely peaking Thursday
  with a Heat Advisory for the I-25 Urban Corridor.

- Some relief this weekend with a chance of storms entering the
  forecast.

&&

.DISCUSSION /Through Tuesday/...
Issued at 243 PM MDT Tue Aug 5 2025

The main attention for the rest of this week will be fire weather
and heat. We`ll address the fire weather situation in the Fire
Weather section below. With regard to heat, not much has changed
over the last 24 hours with the center of a 600dm 500 mb high
expected to park itself over New Mexico through Friday. This,
along with passing shortwaves through the Northern Rockies, keeps
a fairly robust (for this time of year) west/southwest flow aloft
across the forecast area. That spells a continuation of downslope
flow while 700 mb temperatures warm to around 20C each afternoon.
As a result, high temperatures will soar well above normal into
the upper 90s/near 100F across the plains each day through Friday.
It still appears Thursday will be the hottest day, with record or
near record temperatures expected (e.g. Denver`s record is 99F
set in 1980). We think we`ll be right near 100F. That triple digit
heat also requires the issuance of a Heat Advisory for the I-25
Urban Corridor as that bumps up against climatological maxes.

Also adding this bit about smoke, the plumes from Rio Blanco
County fires will be pushing across the northern portion of our
forecast area this evening, and then settling (along with other
smoke from fires in the western U.S.) across much of the area
overnight through Wednesday morning. We`ll likely recycle the
whole thing over again for the rest of this week with active fire
behavior.

With regard to any storm chances, there is just a slight increase
in mid/upper level moisture rotating around the periphery of the
ridge and out of the Desert Southwest. It`s not much, but better
than today`s absolutely ridiculous single digits and teens
dewpoints in the high country. Thus, a couple sprinkles/virga
expected around Park and Summit Counties tomorrow pm. The same
could be said for Thursday. For Friday, it could/should actually
trend a bit drier with more of a westerly flow pattern as a
shortwave moves across the Northern Rockies.

That shortwave finally pushes a front into northeast Colorado by
Friday night, giving us a relief from the heat for this weekend
(highs in the 80s!). Storm chances have actually bumped up a bit
for this period as more troughiness is now advertised over eastern
Colorado. The best chances would be along/east of the Front Range
where low level moisture increases the most. We`ll keep our
fingers crossed for some measurable rainfall in the places that do
get it.

Ensembles suggest getting back into a west/northwest flow aloft
for early to mid part of next week. This would support drier
weather again with temperatures warming to near normal levels
toward Tuesday.

&&

.AVIATION /00Z TAFS through 00Z Thursday/...
Issued at 615 PM MDT Tue Aug 5 2025

VFR through Wednesday, but there will be wildfire smoke in the
area. The main plume is expected to stay north of the Denver area
through Wednesday morning, but there could be some slant
visibility issues in the morning. The plume late Wednesday could
be closer to Denver, but should be mainly aloft through the day.

Winds will be light and variable through about 03z, then normal
drainage patterns with south at KDEN/KAPA and west at KBJC.
There`s some uncertainty about midday Wednesday winds, likely
either light or west around 10 knots, then easterly winds around
10 knots will likely develop.

&&

.FIRE WEATHER...
Issued at 243 PM MDT Tue Aug 5 2025

Concern is for an extended period of critical fire weather
conditions through at least Friday. Humidity readings this
afternoon have plunged into the single digits with winds gusting
to 20-35 mph over the higher terrain. Those critical Red Flag
conditions will persist into the early evening, but winds slacken
off by 7-8 pm. Humidity recovery tonight will be poor in all but
valley locations where only moderate recovery occurs.

Wednesday will feature a continuation of very warm/hot
temperatures with elevated to critical fire weather conditions.
There will only be a very slight bump in minimum humidity compared
to today`s ridiculously low values, so we`ll still see critical
levels of just 8-15% over the forecast area. Winds will slacken
just a bit, but with gusts around 25 mph where stronger flow still
resides over the northern tier of mountains and high valleys
we`ve issued a Red Flag Warning for those zones (211, 213, 217,
and 218).

More critical fire weather conditions are expected Thursday and
Friday. There`s not much change for Thursday humidity-wise, but
unfortunately winds are expected to get an uptick in the high
country due to strengthening flow aloft. This occurs as yet
another shortwave moves across the Northern Rockies and tightens
the mid level pressure gradients. We`ll likely have extensions of
Red Flag Warnings for the mountains and high valleys, and possibly
down the foothills by Friday as winds strengthen even further.

Saturday trends a bit cooler, but we`ll still have some wind to
contend with. More significant relief should finally arrive by
Sunday as winds become light, temperatures cool to below normal
levels, and humidities rebound accordingly. The main chance of
measurable rainfall this weekend would be along and east of the
Front Range mountains.

&&

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

Red Flag Warning from noon to 8 PM MDT Wednesday for COZ211-213-
217-218.

Heat Advisory from 10 AM to 7 PM MDT Thursday for COZ038>040.

&&

$$

DISCUSSION...Barjenbruch
AVIATION...Gimmestad
FIRE WEATHER...Barjenbruch