302
FXUS65 KBOU 201108
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
508 AM MDT Sun Jul 20 2025

.KEY MESSAGES...

- Slightly warmer with less thunderstorm coverage today.

- Increased moisture and slight cooling expected by midweek.

- Warmer again for next weekend.

&&

.UPDATE...
Issued at 501 AM MDT Sun Jul 20 2025

There are a few showers in the northeast corner and a thunderstorm
or two is possible over the next couple of hours. Also updated for
more cloud cover. Rest of the forecast for today is unchanged.

&&

.DISCUSSION /Through Saturday/...
Issued at 156 PM MDT Sat Jul 19 2025

Mid and upper-level moisture is evident on water vapor imagery, as
Gulf moisture is shown being transported into Colorado around an
upper-level high currently centered over OK. This moisture has
allowed cloud cover to keep temperatures a few degrees cooler than
forecast this morning, but the latest observations show that we are
quickly catching up as widespread 80s are now being reported across
the lower elevations. Current observations also show dewpoint
temperatures are in the mid to upper-60s near the NE/WY border,
dropping into the 40s and 50s near the base of the foothills. As the
day progresses, we are expecting afternoon showers and storms to
develop over the higher terrain where SBCAPE values between 500-1000
J/kg are already in place according to the SPC Mesoanalysis. ACARS
soundings show a small cap still in place across the plains, but
as this erodes and storms move off the higher elevations, storms
may strengthen as they enter a more unstable airmass, where
forecast soundings show MLCAPE values between 1000-2000 J/kg, and
35 to 45 kts of 0-6 km bulk shear near the WY/NE borders. Any
storms that develop/move into this environment would be capable of
producing large hail (greater than 2" in diameter), gusty winds
(60-70 mph), and with PWAT values >1", some localized heavy
rainfall would be possible too. Storms are expected to diminish
from west to east, moving out of the forecast area before midnight
tonight.

Slightly warmer and drier conditions are expected for Sunday across
our northern plains as Colorado remains under the aforementioned
broad upper-level ridge centered over the southeast US. Ensemble
means show PWAT values will remain slightly above the norm (~120%)
for the central and southern mountains and the Palmer Divide and
adjacent plains, where isolated to scattered afternoon showers and
ordinary thunderstorms will be possible. Slightly higher
instability and dewpoints are expected for the eastern fringes of
the forecast area that could allow for some stronger storms to
develop, but the greatest CAPE/shear/moisture combo looks to
remain to the east of our forecast area. High temperatures in the
90s are forecast for the plains, while the foothills and mountain
valleys max out in the 80s.

Warmer and drier conditions are expected to start the week on
Monday before we see a steady increase of monsoonal moisture make
it into the forecast area by mid-week. By Wednesday, ensemble
means show PWAT values increasing to near 160% of normal across
the lower elevations. With light winds expected under the
persistent ridge, slow moving showers and storms are forecast to
bring widespread wetting rains, increasing potential for some
heavy rainfall/localized flooding across the forecast area. High
temperatures across the plains are forecast to drop just below
90F for Wednesday and Thursday as the ridge sees some flattening
due to a shortwave passing through the upper-level flow. By the
end of the week, temperatures start their climb back into the 90s
once again as the ridge looks to rebuild, making for another hot
weekend next week.

&&

.AVIATION /12Z TAFS through 12Z Monday/...
Issued at 501 AM MDT Sun Jul 20 2025

VFR through tonight. Isolated thunderstorms are expected between
21z-03z. There is a 30% chance of a wind shift or two with gusts
to 30 knots during that period.

&&

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

&&

$$

UPDATE...Gimmestad
DISCUSSION...Bonner
AVIATION...Gimmestad