513
FXUS65 KBOU 110537
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1137 PM MDT Thu Sep 10 2026

.KEY MESSAGES...

- Mainly dry through Friday with warmer temperatures.

- Return to more unsettled pattern this weekend with a chance of
  thunderstorms especially on Sunday. Cooler Saturday, then warmer
  on Sunday.

- Unsettled pattern to persist through the week, with multiple
  cold fronts expected to bring a few more noticeable cooldowns.

&&

.DISCUSSION /Through Thursday/...
Issued at 1203 PM MDT Thu Sep 10 2026

Another quiet day is on tap for today as a dry airmass resides over
Colorado. Latest satellite and surface observations show that mostly
clear skies are allowing for efficient warming, with temperatures
across the plains already above 80 degrees, mid to upper 60s for
the higher elevations. Afternoon highs are expected to warm into
the mid to upper 80s across the plains, with a few locations
potentially reaching 90. The higher elevations are expected to be
about ten degrees cooler, with mid to upper 70s to low 80s
expected. A line of cumulus clouds resides along a convergence
zone stretching from the eastern Palmer Divide into the Nebraska
panhandle where the greatest surface moisture is in place. SPC
mesoanalysis shows MLCAPE values approaching 500 J/kg along and
east of the boundary today. Given some noticeable vertical growth
on the latest satellite imagery, limited PoPs have been maintained
this afternoon, as any convective development would most likely
occur along this boundary.

Not much has changed in the short term forecast today. Friday
is still expected to be another warm and mostly dry day across
the forecast area. A little increase in mid-level moisture
still looks to move into the higher elevations. We could see a
few high-based showers in our northern mountains in the
afternoon, but instability remains limited. CAMs show potential
for some high-based virga showers to move across the plains in
the late afternoon, but this would likely just lead to some gusty
outflows and nothing more than a trace of precipitation. Between a
few degrees of warming at the 700 mb level and downsloping winds,
afternoon highs are forecast to warm into the 90s across the
plains ahead of a cold front Friday night. A few late night
showers will be possible with the cold front, mainly for the
northern mountains and foothills.

A brief cooldown is expected on Saturday behind the cold front.
Ensembles are in agreement that we will see some better moisture
return to the forecast area throughout the day as the next
shortwave trough moves into the Pacific Northwest and starts to
turn flow aloft more southwesterly. However, they differ fairly
significantly on how much moisture we manage to tap into. Between
the ECMWF and GFS ensembles, PWAT anomalies will range from 100%
to 160% of normal Saturday afternoon. Even with the discrepancies,
between the increased moisture and better instability expected (a
few hundred Jules of MLCAPE), scattered afternoon showers/storms
are expected to return to the higher elevations.

Some slight changes in the long term forecast are present today
as the NBM seems to be getting a slightly better handle on the
arrival time of a few cooler air masses. Sunday is still on track
to be a hot one, with afternoon highs expected to reach the mid
90s across the plains. There is better agreement that moisture
will increase a tad more and move into the lower elevations.
MLCAPE is expected to bump up to 600-1000 J/kg across the plains,
which could allow for some stronger storms to develop.

A more active and cooler pattern will remain in place through the
week, with multiple cold fronts expected to bring a few cooldowns
and precipitation chances. Monday is now looking to be warmer than
previously expected, with afternoon temperatures within a few
degrees of normal ahead of a cold front that is now looking to
arrive overnight. While there is still some time for things to
change, it`s looking like Tuesday will bring a significant
cooldown, with afternoon highs struggling to climb out of the 60s
for much of the lower elevations, and at least one more cold front
possible by the end of the week.

&&

.AVIATION /06Z TAFS through 06Z Saturday/...
Issued at 1137 PM MDT Thu Sep 10 2026

Southerly enhanced drainage winds at KDEN will gradually relax
through 08Z, with normal speeds of 8-12 kts resuming. Light and
variable winds should then develop toward 16Z. There is still some
uncertainty in prevailing wind direction by 20Z, with a battle
between diurnal upslope and stronger westerlies trying to advance
off the foothills. For now, we`ve kept a NE-E component at KDEN
and KAPA, with a more W-NW wind likely at KBJC. We`re also
monitoring for a chance of virga with gusty outflow winds 22Z
Friday to 02Z Saturday, as DCAPE will abound (growing to 800-1200
J/kg) in what we think should be a relatively deep inverted-v
profile. We may need to add a PROB30 VRB G30kts to TAFs with
upcoming AMDs as probabilities continue to grow with enough mid
level moisture arriving late in the day.

&&

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

&&

$$

DISCUSSION...9
AVIATION...20

NWS BOU Office Area Forecast Discussion