613
FXUS65 KBOU 270555
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1155 PM MDT Sun Jul 26 2026

.KEY MESSAGES...

- Some relief from the heat arrives Monday, with increasing
  chances of showers and afternoon/evening thunderstorms.

- Increasing chances for thunderstorms with locally heavy rain
  Tuesday and Wednesday. Temperatures settle back closer to
  normal.

- Drying out again later in the week.

&&

.DISCUSSION /Through Sunday/...
Issued at 249 PM MDT Sun Jul 26 2026

The scorching heat continues across Colorado today with triple digit
afternoon highs expected for the low elevations. Given midday
temperatures in the upper 90s to even a few 100s, it is likely that
multiple station daily records will either be tied or broken. Below
is a sampling of forecast and record temperatures;

CityForecastOld Record

Denver:    102100 in 1910
Fort Collins:  102100 in 1910
Boulder:   101 98 in 1935
Greeley UNC:   105102 in 2003
Fort Morgan:   106106 in 1910
Akron:   101104 in 2003
Julesburg:   105105 in 1894
Limon:    100  98 in 2023

Monsoonal moisture has already facilitated the development of a few
showers and thunderstorms over the mountains. Just like yesterday,
these showers and storms will have the potential to produce gusty
outflow winds up to 40 mph as they move off the foothills and
dissipate over the Denver metro area in the late afternoon and
evening. The development of showers and outflows could encourage
sporadic periods of "cooler" breeziness that bring slight heat
relief. However, cloud cover could also work to trap heat near the
surface by preventing nighttime radiative cooling from occurring.
As such, we expect temperatures tonight to be rather warm, only
dropping into the mid 70s in parts of the Denver metro.

For tomorrow, the center of the upper level anticyclone associated
with the longwave ridge over the western CONUS will be positioned
over southeast Colorado. Very weak south to southwesterly flow aloft
will continue to allow monsoonal moisture to increase over the
region with precipitable water (PW) values that greatly exceed
climatological average (150%-200% of normal). For the Denver metro,
this means that PW values will range around 1.4"-1.6", with a few
long-range ensemble members suggesting as high as 1.8". Over the
mountains, PW values will be around 0.75" both west and east of the
Continental Divide. These anomalous PWs, combined with very slow
storm motions (< 15KT cloud layer winds), and long-skinny CAPE
sounding profiles, will lead to an increased risk of flash flooding
particularly with any storms that become anchored to the high
terrain. The only ingredient that does not seem to be favorable for
efficient rainfall production is a very shallow warm cloud layer,
which is surprising for the warm airmass in place.

Tuesday`s setup looks to be very similar to Monday`s. PWs will still
be around 150% of normal, and the warm cloud layer will perhaps a
bit more favorable for heavy rain, as deep as 5,000ft. By Wednesday,
PWs are still anomalously high although faster storm motions will be
in place due to flow aloft becoming more zonal. Model guidance has
also suggested a weak shortwave trough passage on Wednesday
afternoon, which could provide additional lift for showers and
thunderstorms to develop.

In summary, Monday, Tuesday, and Wednesday exhibit almost all of the
necessary ingredients to support localized heavy rainfall with only
a few fluctuations. It is difficult to tell which of these days will
have the highest rain chance given the erratic nature of monsoonal
storms as well as terrain interactions. High temperatures will run
closer to normal (low to mid 90s over the plains) due to the
increase in cloud cover and isolated to scattered shower coverage
each afternoon. Monsoonal moisture greatly decreases on Friday,
and long- range ensembles suggest a warming trend for the weekend,
with ensemble mean temperatures reaching the triple digits over
the plains once again for Sunday.

&&

.AVIATION /06Z TAFS through 06Z Tuesday/...
Issued at 1155 PM MDT Sun Jul 26 2026

Isolated showers had developed near KDEN at the start of this
period, and one more gusty southwest outflow moved through. Winds
may settle down again by 07Z-09Z and become VRB, depending on how
the current outflow reacts with the potential northerly surge
moving south across the northeast Colorado plains. Later tonight,
winds should settle to more of a W-SW at less than 10 kts, before
turning more northerly 15Z-18Z Monday. An isolated light
shower/sprinkle or two in the vicinity would be possible during
this period.

We expect an increase in convective activity as more moisture
moves across the region Monday afternoon and evening. However,
there is considerable uncertainty in timing and location due to
extensive mid level cloud cover, slight cooling, and capping.
Thus, we`ll maintain consistency at this point with a period of
gusty winds (TEMPO) due to -SHRA and/or -TSRA nearby anytime after
21Z Monday, potentially lasting into the late evening but with
lower PROB30.

&&

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

&&

$$

DISCUSSION...AA
AVIATION...20

NWS BOU Office Area Forecast Discussion