599
FXUS65 KBOU 261135
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
535 AM MDT Sun Jul 26 2026

.KEY MESSAGES...

- Record heat today, with highs 100-106 across the plains and I-25
  Corridor. Heat Advisory expanded to Palmer Divide.

- Scattered afternoon/evening thunderstorms, mostnumerous over
  the higher terrain.

- Increasing chances for thunderstorms with locally heavy rain
  Monday, Tuesday, and Wednesday. Some relief to extreme heat.

- Drying out again later in the week.

&&

.DISCUSSION /Through Saturday/...
Issued at 218 AM MDT Sun Jul 26 2026

Just when you think it couldn`t get any hotter, we`re staring into
the face of what looks to be the hottest day of the year today.
The heart of both the upper level ridge and mid level thermal
ridge will be centered across the Front Range. 700-600 mb
temperatures warm another 0.5-1.0C, which means we`ll tack on
another degree or two to yesterday`s highs that exceeded 100F
over most of the plains and I-25 Corridor. That means record
temperatures are forecast for many stations, with a sampling
below;

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

Given a further uptick in temperatures, we`ve expanded the Heat
Advisory to also include the Palmer Divide where more significant
heat impact levels are forecast. Warm overnight lows, and in some
places record high minimums, are only further intensifying the
heat impacts today.

With regard to any storm chances, the mid level water vapor loop
and latest ACARS soundings show similar to just a slight uptick in
moisture values across the area. Therefore, we expect a similar
day to yesterday when we saw scattered showers and a few storms in
the afternoon, with the highest coverage over the mountains and
Palmer Divide, and lower chances as we head to the east with
blazing sunshine expected through the afternoon. At least there
will be a little heat relief due to clouds and shower outflows
in/near the mountains late in the day.

For tonight, it`ll be another warm one as cloud cover is expected
to increase with a push in mid/upper level monsoonal moisture.
Some areas near the lower foothills and Denver metro area may only
reach the mid 70s for overnight lows. Fortunately, it appears the
clouds will help limit heating for Monday, with some of the short
term guidance showing sufficient cloudiness to keep us away from
another day of Heat Advisories. The clouds may also impact
convective development, but typically enough heating occurs to get
late day showers and storms going. This time, they may linger
well into the overnight hours Monday night which would be more
typical of a monsoonal moisture surge. As precipitable water (PW)
values increase to 150-200% of normal, some of the storms will be
capable of producing locally heavy rainfall.

That threat may very well grow into Tuesday as we`ll be approaching
climatological maxes for PW. At the same time, warm cloud depths
increase a little to 3,000-4,000 feet but that`s still less than
optimal given the very warm airmass and still deep subcloud
layer. All other parameters are more favorable including slow
storm motion (15 mph or less), high PW, and potential for skinny
CAPE profiles above the LCL. Thus, we`ll continue to watch for
locally heavy rainfall and any flash flood threat. Wednesday could
be another similar setup with scattered to numerous showers and
storms with locally heavy rainfall, although storm motions will
likely increase as the ridge flattens and a shortwave moves
through. Temperatures are expected to settle closer to normal
(still above, though) as we head into this more unsettled pattern
and a couple backdoor "cool" fronts are expected.

After that, the upper level ridge is still forecast to retrograde
into the Great Basin late next week through next weekend. This
would start to advect in drier air in the mid/upper levels in NW
flow aloft. At the same time, low level moisture could still hold
east of the Rockies. We do think overall coverage of afternoon/
evening showers and storms will be on the decrease, which means
temperatures will likely be on the rise by next weekend.

&&

.AVIATION /12Z TAFS through 12Z Monday/...
Issued at 535 AM MDT Sun Jul 26 2026

A quicker than normal turn to W-NW-N is expected through 16Z, with
N-NE winds prevailing 17Z-00Z. However, isolated high based
convection will likely throw some VRB winds at the airports
anytime 21/22Z-06Z. We`ve included a PROB30 for this potential.
Winds beyond 00Z through the overnight are tricky, with much of
the guidance pointing to a W-NW component so will lean that way
for now.

Record heat will lead to abnormally high density altitude (9,000
feet or more) during the peak heating hours today.


&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 10 AM this morning to 9 PM MDT this evening
for COZ038>051.

&&

$$

DISCUSSION...20
AVIATION...20