097
FXUS65 KBOU 061928
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
128 PM MDT Thu Aug 6 2026

.KEY MESSAGES...

- Isolated thunderstorm possible for the far northeastern plains
  this afternoon.

- Elevated to locally critical fire weather conditions possible
  across the mountains and high valleys through the weekend.

- Hot this weekend with highs reaching 95 to 105 across northeast
  Colorado. A Heat Advisory has been issued for the Denver metro
  Saturday.

- Precipitation chances increase towards midweek next week.

&&

.DISCUSSION /Through Thursday/...
Issued at 122 PM MDT Thu Aug 6 2026

Relatively quiet conditions expected for the rest of the day today,
aside from an isolated threat of storm for the far northeastern
plains this late afternoon. With the upper level ridge
restrengthening over the desert southwest, heat has begun to build
over the plains today, and will likely continue to build through the
weekend. Despite increased smoke concentration, we have still been
able to warm up to the 90s by noon, and will likely reach mid 90s by
the end of the day.

In terms of any storm threat this afternoon/evening, surface
observations shows an axis of low-level moisture reaching up to the
far northeastern plains, with dewpoint temperatures in the low 60s.
Moderate instability will be in place, as evident in modeled Skew-T
soundings that show MLCAPE of 1400-1800 J/kg. While most CAMs keep
our forecast area capped and dry, some models do indicate an
isolated storm initiating in Nebraska and trekking down into
Sedgwick and Phillips counties. Confidence is low on this
occurring, especially given the lack of any forcing in the area.
However, have upped PoPs (10-20% chance) to account for that
possibility. If a storm is able to develop, strong out flow winds
of 40-50 mph and hail will be the main concerns.

Friday will be similar to today, with temperatures reaching up to
the mid-90s again and smoke creating hazy skies. There will be
elevated to locally critical fire weather conditions for the
mountains and high valleys given how dry we will be (relative
humidity values between 8-15%), however winds should remain below
critical thresholds for the most part.

The upper level ridge will continue to strengthen through the
weekend, with the axis of the mid-level thermal ridge shifting into
eastern Colorado by Saturday/Sunday. 700-mb temperatures are
expected to reach up to 19-22 C, resulting in highs soaring into
the 100s for most of the plains. Given HeatRisk levels reaching up
to 3 (correlating to high risk for much of the population,
especially those who are heat sensitive and those without
effective cooling/hydration), have opted in to issue a Heat
Advisory for the Denver metro and portions of the Urban corridor,
including Boulder. Overnight lows should dip into the 60s Saturday
night so decided against on the Heat Advisory going into the
overnight hours of Saturday. However, with temperatures soaring
to the high 90s/low 100s again on Sunday, another Heat Advisory
will likely be needed.

Another concern for Saturday will be elevated to locally critical
fire weather conditions for the northern mountains and high valleys.
Relative humidity values should drop to 9-15% by the afternoon, with
west/ northwesterly winds gusting up to 20-25 mph. There is still
some uncertainty in magnitude and duration of the stronger wind gusts,
so have refrained from any highlights. However, if we continue to
trend towards gusts of 20-30 mph for a large portion of the day,
then a Red Flag Warning will be needed.

With moisture slightly increasing by Sunday (still below normal
precipitable water values), afternoon showers and thunderstorm
chances begin to increase for the mountains. Towards the beginning
of next week, guidance does have the upper level high weakening, but
models continue to differ on exact evolution of the ridge. Will it
reside in the Four Corners region or track more east closer to
Texas? It is still uncertain right now, but this placement will
affect how much monsoonal moisture we receive towards midweek.
The ECMWF favors a weaker ridge with the axis shifting more east,
and thus better moisture for us. The GFS, however, favors a more
westerly placement of the high, and thus less moisture transport
into the region. It is interesting to note that the AIGFS aligns
more with the ECMWF, so will be keeping watch to see if future
runs of the GFS changes. Regardless, we are expecting increasing
chances for precipitation for the mountains and plains towards the
end of next week.

&&

.AVIATION /18Z TAFS through 18Z Friday/...
Issued at 1145 AM MDT Thu Aug 6 2026

As seen on ACARS soundings, the inversion that was in place this
morning is starting to mix out and should give way to northeast
winds this afternoon. HRRR Smoke continues to show smoke
persisting at all three terminals throughout the TAF period with
the possibility for some slantwise visibility issues at times.
Otherwise, a typical diurnal wind pattern is expected. No ceiling
issues are forecast and winds should stay under 12 kts.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM to 8 PM MDT Saturday for COZ039-040.

&&

$$

DISCUSSION...MAI
AVIATION...MV

NWS BOU Office Area Forecast Discussion