735
FXUS65 KBOU 152252
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
452 PM MDT Wed Jul 15 2026

.KEY MESSAGES...

- Hot weather continues through this weekend, peaking again toward
  Sunday. Elevated fire weather conditions across most of the
  area, although we`ll stay shy of any Red Flag criteria.

- Monsoonal moisture is lacking through Saturday with only
  isolated to scattered afternoon/early evening storms in the
  mountains. Dry plains.

- More significant monsoonal moisture and cooler temperatures are
  still on course to arrive early next week, along with a threat
  of locally heavy rainfall.

&&

.DISCUSSION /Through Wednesday/...
Issued at 130 PM MDT Wed Jul 15 2026

Hot and dry weather continues across the lower elevations, while
isolated to scattered storms are developing once again in the
mountains. This will be the daily routine through Saturday. Then a
significant weather pattern change is on track for early next
week.

The isolated to scattered storm coverage (most numerous in Park
and Summit Counties) will end early this evening with the loss of
daytime heating. The plains will remain dry, although there is a
very low risk of a brief isolated shower/storm developing near the
base of the foothills should an outflow boundary support enough
convergence to break a relatively weak cap. The rinse and repeat
forecast will remain in force through the rest of the week.
Sufficient moisture and the elevated heat source of the Rockies
will continue to support isolated to scattered convection over the
mountains each afternoon and early evening, while the plains will
almost certainly be capped off each day. After closer to normal
temperatures (still a few degrees above) Thursday and Friday,
temperatures will start to inch up with mid to upper 90s becoming
more common for highs across all of the plains and I-25 Corridor
by Saturday. That occurs as the heart of the upper level
subsidence appears to slide westward allowing some warming in the
mid levels. That may also drop coverage of any late day
showers/storms in the high country, or even shift them farther
west altogether into western Colorado.

Sunday is still shaping up to be the hottest day, with potential
of reaching the 100F degree mark in portions of the I-25 Corridor.
700 mb temperatures are advertised to increase to nearly 21C. With
warmer nights, we`ll likely be approaching Heat Advisory criteria
for Sunday.  Ensembles show just a slight uptick in monsoonal
moisture as the upper high parks itself over the region and
monsoonal plume shifts ever so slightly eastward. The exact
timing is uncertain, but appears it will be enough to see a bump
in mountain convection and a slight chance of storms moving onto
the I-25 Corridor as there are finally hints of a westerly
component in the steering flow.

Monday is when the weather pattern starts a meaningful change.
While it could still be hot, there is reasonable agreement that
precipitable water (PW) values take a jump to much above normal
values (nearly 1.2" for Denver). That would support higher storm
coverage and intensity, with a few storms potentially producing
locally heavy rainfall.

The odds of storms with locally heavy rain and even potential for
flash flood risk will be increasing into Tuesday and Wednesday.
There is excellent agreement in the ensembles that show the
full/deep plume of monsoonal moisture shifting across the
forecast area. At the same time, a weak backdoor cool front or two
will likely aid in upslope flow and low level moisture advection.
It was interesting to note that average PW increases to 1.3-1.5"
for the Denver area, with the EC ENS having the highest values
near 1.5" (seems overdone as only 3 soundings from Denver have
EVER exceeded 1.5" PW). But, even the GEFS average near 1.3" PW by
Wednesday is extremely impressive, and those values would
essentially put us near the average daily maxes for this time of
year! Thus, we`ll be watching this setup and of course all of the
daily challenges (e.g. frontal surges, stability, moisture
profiles, and PW) to assess and refine our potential for heavy
rain/flash flood risk as we move toward next Tuesday and
Wednesday. Whatever the case, we will be trending cooler to below
seasonal normals, with increasing chances of measurable if not
significant precipitation.

&&

.AVIATION /00Z TAFS through 00Z Friday/...
Issued at 446 PM MDT Wed Jul 15 2026

VFR conditions throughout the TAF period. East or east-southeast winds
will slowly veer towards a 140-150 direction later this evening.
These winds will be on the stronger side with gusts up to 25
knots at DEN and APA. A weak boundary will move through BJC around
08-10Z overnight shifting winds from the southeast to the
northwest. This boundary will likely move towards DEN and APA
between 11-13Z shutting off the drainage winds and shifting winds
more to the west or southwest.

Similar wind conditions to Wednesday are expected during the late
morning and afternoon on Thursday. Wind speeds will be a bit
lighter given less of a surface gradient and winds will likely
have a more northeasterly direction during the afternoon.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...20
AVIATION...Danielson