646
FXUS65 KBOU 312358
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
558 PM MDT Fri Jul 31 2026

.KEY MESSAGES...

- Isolated thunderstorms through the afternoon and evening. A
  couple strong storms remain possible, with strong outflow winds
  and small hail as the main threats.

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

- Heat Advisory now in effect for the I-25 corridor from Sunday
  through late Monday evening.

- A little cooler for Tuesday and Wednesday, but warm and
  generally dry conditions will continue for the next several
  days.

&&

.DISCUSSION /Through Friday/...
Issued at 1226 PM MDT Fri Jul 31 2026

Water vapor satellite shows little moisture over most of the state
at this point, as a broad ridge sits near southern AZ/NM this
afternoon. There`s just enough surface moisture lingering across
the Front Range/I-25 corridor this afternoon, which has led to a
narrow corridor of MLCAPE >500 J/kg. Across some of the higher
elevations of the Front Range, we`ve already seen some weak
convective development, though most of the lower foothills and
urban corridor remain largely capped.

With continued light upslope through the rest of the afternoon,
most guidance slowly dissolves the CAP evident between 800-650mb
(per recent ACARS soundings), which should allow for convection to
gradually shift into the I-25 corridor later this afternoon and
evening. Any more robust updraft would be capable of producing at
least some small hail, but the primary threat would be gusty
outflow winds with ample DCAPE (>1250 J/kg) available today.

The upper ridge is expected to strengthen over the desert
southwest on Saturday, with 500mb heights approaching 600 dam.
The thermal ridge will largely stay to our west during the day,
but we should see temperature warm back into the low to mid 90s
across the plains. As subsidence increases and the little
remaining boundary moisture starting to mix out, only a couple of
weak showers are expected across the higher Front Range mountains
during the afternoon with mostly sunny skies elsewhere.

The ridge is expected to weaken/flatten a bit by Sunday and
Monday, but this also allows warmer mid-level temperatures to push
into our forecast area. 700mb temperatures reach roughly 20-22C
(near the edge of model climatology) both days, which should lead
to high temperatures reaching the upper 90s to low 100s. Guidance
continues to oscillate between what day will be the warmer of the
two - but either way, it will be hot. With overnight lows only
falling into the upper 60s/near 70F overnight, we`ve gone ahead
and extended the Heat Advisory all the way through Monday evening.

There should be a day or two of cooler weather next week as a cold
front attempts to push into the lower elevations Tuesday morning.
There may be enough moisture behind the front for a few scattered
showers/storms Tuesday, though widespread precipitation remains
unlikely. The main question is if cooler weather will manage to
continue into Wednesday, or if we`ll simply see a quick return to
above normal temperatures. It`s possible (probable?) that the NBM
is still too warm for Wednesday, with highs more likely to end up
in the mid/upper 80s vs the low 90s in the forecast.

Any cooler weather will quickly be replaced by highs in the
mid/upper 90s by the latter portion of the upcoming week, as the
ridge begins to restrengthen off to our west. With most of our
forecast area in zonal or northwesterly flow, there won`t be much
monsoon moisture to work with through most of next week.

&&

.AVIATION /00Z TAFS through 00Z Sunday/...
Issued at 557 PM MDT Fri Jul 31 2026

Current radar imagery shows a few thunderstorms in the vicinity of
KBJC and KAPA that are moving east over the Denver metro. As such,
we have extended the PROB30 for -TSRA and erratic gusty outflows
until 03Z. Winds are otherwise easterly over the region, and we
expect drainage S-SSW flow to kick in around 06Z this evening.

Conditions will be mostly clear and quiet for tomorrow. Winds will
follow a diurnal pattern, starting out SW and turning clockwise
throughout the day. There is a bit of uncertainty regarding smoke
concentrations from the wildfires in the Pacific Northwest. However,
concentrations will likely stay low enough to only impact slant-
range visibility around sunrise and sunset, when the sun angle is
low.

&&

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

&&

$$

DISCUSSION...Hiris
AVIATION...AA

NWS BOU Office Area Forecast Discussion