484
FXUS65 KBOU 200512
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1112 PM MDT Sun Jul 19 2026

.KEY MESSAGES...

- Hot weather continues through Monday, with highs pushing near
  100F over the I-25 Corridor and adjacent plains. A Heat Advisory
  remains in effect for the Denver Metro/I-25 corridor through 9
  PM Monday.

- Scattered afternoon/early evening storms in the mountains
  expected Monday, with the plains remaining dry.

- Arrival of monsoonal moisture still getting delayed slightly,
  but once it arrives it should last into late next week. Storms
  from Tuesday or Wednesday onward will be capable of producing
  locally heavy rainfall.

- Only a slight cooling trend forecast this week with the arrival
  of better moisture.


&&

.DISCUSSION /Through Sunday/...
Issued at 309 PM MDT Sun Jul 19 2026

Heat and hints of monsoonal moisture have allowed scattered
thunderstorms to develop over the Northern Mountains this afternoon,
and satellite imagery also shows cumulus cloud cover increasing over
the Front Range. Shower activity will diminish near sunset this
evening. Across the low elevations, temperatures have had no trouble
climbing into the upper 90s.

The forecast remains on track for tomorrow being the hottest day of
the week (and perhaps a contender for hottest day of the year), with
essentially all model guidance suggesting Denver will hit 100F in
the afternoon. These high temperatures are supported by a slight
eastward shift of the upper-level ridge axis. Additionally, the mid-
level core of the airmass accompanying this ridge will be centered
right over the state of Colorado Monday afternoon, with 700mb
temperatures nearing 20C, which exceeds the 95th percentile of
climatology.

Temperatures will generally trend "cooler" Tuesday through Saturday,
though still hot (closer to average for the time of year), reaching
the low to mid 90s each day at the low elevations. The mountains
will also see high temperatures near average (70s-80s) with a better
chance of experiencing some heat relief with isolated storms as
monsoonal moisture increases throughout the week.

We expect afternoon showers and thunderstorms over the high terrain
to become more scattered in nature Monday and Tuesday as the upper-
level ridge drifts southeast. However, model guidance has continued
to delay the arrival of the highly anticipated monsoonal moisture
with the brunt of the moisture now arriving late Wednesday into
Thursday. Nevertheless, each day will have a slightly different
setup regarding moisture and forcing mechanisms, especially over
the Denver metro and eastern plains.

A cold front will bring a northerly push of moisture to the eastern
Colorado plains Tuesday morning which, combined with weak
southeasterly flow, could aid in the development of a few showers
over the foothills and Palmer Divide in the late afternoon and
evening. More substantial moisture arrives on Wednesday as
another northerly push of moisture arrives from the northern
intermountain west region and southerly flow strengthens,
advecting moisture from the central plains. Model guidance has
also been suggesting the development of a lee cyclone north of the
Denver metro area, which would also help channel moisture farther
west into the I-25 corridor, the foothills, and the Northern
Mountains. Uncertainty remains regarding the fine details of how
the rainfall later this week will play out. However, it is worth
mentioning that long- range ensembles continue to suggest
precipitable water (PW) over the Denver metro area reaching or
even exceeding values of 1.4" Wednesday and Thursday, which is
about double the climatology for this time of year (0.7-0.8"). A
shortwave trough passage on Thursday could provide additional lift
for shower activity over the mountains and northern plains. Given
the weak flow aloft and and slow storm motions in place, we will
continue to watch how flash flood potential evolves through the
week.

&&

.AVIATION /06Z TAFS through 06Z Tuesday/...
Issued at 1108 PM MDT Sun Jul 19 2026

Winds will remain from the south overnight except at BJC which
will become light WNW by 07z. On Mon, light and variable winds in
the morning will become east by 18z and then more ESE by 23Z.
Outflow boundaries from tstms over the higher terrain may move
across by 01z which could lead to a 20-30 percent chc of tstms
thru 04z. Thus have included a Prob30 for this scenario.


&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 9 PM MDT Monday for COZ038>040-043.

&&

$$

DISCUSSION...AA
AVIATION...RPK

NWS BOU Office Area Forecast Discussion