876
FXUS65 KBOU 311106
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
506 AM MDT Fri Jul 31 2026

.KEY MESSAGES...

- Isolated thunderstorms possible in the afternoon. A few storms
  could become severe, with strong outflow winds and hail as the
  main threats.

- Heat returns by the weekend, with temperatures reaching up to
  the 100s on Sunday and Monday.

- Heat Advisory for the Urban Corridor and Greeley Sunday
  afternoon.


&&

.DISCUSSION /Through Thursday/...
Issued at 239 AM MDT Fri Jul 31 2026

Current nighttime microphysics RGB satellite product shows low
stratus clouds in Nebraska trekking southwest. Guidance does keep
the stratus deck from entering Colorado (besides possibly the far
northeastern plains) this morning, which will help build a
favorable set-up for today`s thunderstorm potential. Isolated
showers and thunderstorms are possible this afternoon, with
convection initiating in the mountains by late morning/early
afternoon before spilling onto the adjacent plains through the
early evening. Modeled Skew-T soundings show steep low and mid-
level lapse rates, with DCAPE values of 1300-1600 J/kg. This would
favor strong-to-severe outflow winds up to 60 mph, particularly
for the southern I-25 Corridor and Palmer Divide area where
instability will be best. SPC has a Marginal Risk (1/5) for severe
storms for that area today. However, any strong storm that
develops over the plains has the potential for strong outflow
winds as well. While confidence is low, there is also an isolated
hail threat with the strongest storms today. One hindrance to
today`s storms would be near-surface smoke from wildfires in the
northwestern United States. If smoke is able to advect into the
plains this afternoon, it could act as a cap for storm
development.

The upper level ridge will likely restrengthen over the Four Corners
region by this weekend, which will bring the return of drier and
warmer conditions. Ensemble guidance continues to indicate
temperatures reaching near or over 100 F for the Urban Corridor by
Sunday. With Heat Risk expecting to get up to 3 (correlating to High
Risk for much of the population, especially those sensitive and
without effective cooling) have opted in to issue a Heat Advisory
for much of the Urban Corridor and the adjacent northern plains
(including Greeley where temperatures could reach up to 105 F).
Monday will likely see similar temperatures and an additional
Heat Advisory may be needed in the next forecast package.

We will likely see a reprieve of hot temperatures by Tuesday, as an
upper level trough is progged to trek north of Colorado. Ensemble
solutions favor temperatures in the mid-to-high 80s for much of the
plains. We could also see scattered showers and thunderstorms by
midweek, however ensemble guidance does not seem too optimistic
about widespread measurable rainfall. Temperatures should climb
back to the mid 90s towards the end of the week.

&&

.AVIATION /12Z TAFS through 12Z Saturday/...
Issued at 501 AM MDT Fri Jul 31 2026

VFR conditions expected through the TAF period. Winds are
currently light and generally from the northwest at all terminals.
Expect this to continue through the morning hours before northeast
winds take place. Isolated showers and thunderstorms are possible
this afternoon, however there is some uncertainty with exact
coverage of storms. Have kept the PROB30 as is for this reason.
Main concerns will be lightning and outflow winds of 30-35 kts.

With northwest flow aloft, guidance has smoke from wildfires in
the northwest advecting smoke into the plains by the afternoon.
Due to model run consistency, have opted in to put smoke in the
TAF for DEN, with the possibility of slant-wise visibility issues
on approaches.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon to 9 PM MDT Sunday for COZ038>043.

&&

$$

DISCUSSION...MAI
AVIATION...MAI

NWS BOU Office Area Forecast Discussion