066
FXUS65 KBOU 040618
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1218 AM MDT Tue Aug 4 2026

.KEY MESSAGES...

- Elevated to critical fire weather conditions likely across the
  high mountain valleys through the next few days.

- Cooler today and Wednesday before temperatures gradually warm
  back to the triple digits by next weekend.

&&

.DISCUSSION /Through Monday/...
Issued at 132 PM MDT Mon Aug 3 2026

As expected, it`s hot across the I-25 corridor and plains this
afternoon. Temperatures have already eclipsed 100F at several
locations, with places like KDEN not too far behind (currently
99F). These temperatures are rather impressive, especially given
the lingering haze/smoke across the plains along with some
scattered mid-level cloud cover. We probably have another couple
degrees of warming this afternoon, with highs generally hitting
the 100-103F range across the I-25 corridor.

What remains to be seen is how many showers are able to develop
this afternoon. ACARS soundings and SPC Mesoanalysis show very
meager instability, but DCAPE currently sits at about 1800 J/kg.
It also seems possible (probable) that the HRRR is overdoing the
amount of convection this afternoon, just based on satellite
trends to start the afternoon. We still expected isolated to
widely scattered showers, which would likely produce more wind
(gusts up to 50 mph) than rain.

Meanwhile, a strong cold front is still on track to arrive later
this afternoon. The front looks to be moving through Cheyenne at
the moment, with notable pressure rises across eastern Wyoming.
This is expected to reach the Denver metro by about 5-6PM today,
which should provide substantial relief from the heat... while
also advecting some near surface smoke into the area for the
evening hours. While smoke will persist through most of Tuesday,
we will at least see much cooler temperatures for the plains...
with highs in the mid/upper 70s. Temperatures will warm back into
the low to mid 80s by Wednesday.

The higher elevations won`t feel the effects of the cold front,
and will instead have to contend with fire weather concerns over
the next few days, as zonal flow aloft begins to strengthen. A Red
Flag Warning has been issued for North Park and Middle Park on
Tuesday and additional highlights may be needed for Wednesday and
Thursday.

Our brief cooldown will quickly be replaced by hotter and drier
conditions as the upper ridge once again strengthens over the
Four Corners region late this week into the upcoming weekend. With
mid-level temperatures once again approaching 20-22C this would
likely lead to highs approaching 100F on Saturday and Sunday. The
position of the upper ridge would also limit any chance of monsoon
moisture making a return until at least early next week.

&&

.AVIATION /06Z TAFS through 06Z Wednesday/...
Issued at 1145 PM MDT Mon Aug 3 2026

Current satellite and observations show stratus are quickly
developing along the Front Range late tonight from persistent
upslope flow. Latest KBDU METAR shows cloud base are around
6,000`AGL and approaching KBJC (already in the vicinity). With
upslope expected to remain in place overnight, continued
moistening of the lower levels should keep stratus developing and
spread eastward across the other two TAF sites within the next
hour. Latest guidance shows CIG should remain between 3,000` to
5,000` AGL before gradually scattering out after 12Z, but there is
still a low chance (10-15%) that we see a few hours of CIG as low
as 2,000` AGL, with KBJC having the best chances for this outcome.

Smoke is expected to remain in the area through the TAF period,
keeping potential for slant range visibility concerns, though
there may be a few hours of clearer skies throughout the day.

Winds are expected to maintain a NE to easterly component through
the day today. Low confidence in winds late tonight as latest hi-
res guidance shows drainage winds will struggle to settle in
as a cyclone forms near the TAF sites. Depending on where the
cyclone forms will determine wind speeds and direction as well as
where a potential shear zone forms.



&&

.FIRE WEATHER...
Issued at 132 PM MDT Mon Aug 3 2026

Observations early this afternoon show some spotty elevated fire
weather conditions across the high mountain valleys, where
humidity has fallen to around 15-20% with a few gusts of 20-25
mph. We may eventually see some elevated fire weather conditions
across the plains as winds increase this evening ahead of a fairly
strong cold front.

While the cold front will limit fire danger across the plains for
the next couple of days, the front doesn`t look to be deep enough
to provide much relief for the higher elevations. Zonal flow is
expected to develop on Tuesday, and with deep mixing... it looks
likely that North Park and Middle Park will see deep enough mixing
to support a few hours of Red Flag conditions during the afternoon
and early evening hours.

The flow aloft is expected to turn a little bit more northwesterly
by Wednesday and Thursday, with 700-500mb winds also weakening
slightly. Most guidance still supports at least elevated fire
weather conditions across most of the high mountain valleys... and
additional highlights may be needed later this week.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 1 PM to 7 PM MDT Tuesday for COZ211-213.

&&

$$

DISCUSSION...Hiris
AVIATION...9
FIRE WEATHER...Hiris

NWS BOU Office Area Forecast Discussion