132
FXUS65 KBOU 101821
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1221 PM MDT Mon Aug 10 2026

.KEY MESSAGES...

- Very warm temperatures to continue through Tuesday, then start
  to cool Wednesday and fall below normal Thursday.

- Another round of high-based virga showers today. Wind gusts
  of30-45 mph are possible from the showers.

- Slight chance for strong to severe thunderstorms over far
  northeast Colorado late this afternoon and evening.

- Monsoon moisture becomes plentiful beginning Wednesday bringing
  daily rounds of showers and thunderstorms through the rest week
  and weekend. Locally heavy rainfall and localized flooding are
  possible.

&&

.DISCUSSION /Through Monday/...
Issued at 1217 PM MDT Mon Aug 10 2026

The upper level ridge will continue to dominate the weather today
and tomorrow, before a pattern change brings relatively cooler
temperatures and increased chances in precipitation chances
beginning Wednesday. Today will be similar to what we have been
seeing over the weekend, with temperatures in the mid-to-upper
90s and scattered showers and thunderstorms for the mountains and
plains. Current satellite imagery shows that cumulus has
developed, with virga showers already popping up across mountains
and portions of the I-25 corridor. ACARS soundings still show a
very dry airmass at the low-levels, so expect most of the showers
to produce little to no rainfall for the plains. However, with the
increase in moisture, a few of the stronger storms likely will
produce light rainfall amounts. SPC mesoanalysis page has DCAPE
values ranging from 900-1300 J/kg, so gusty winds of 30-45 mph (a
few could be stronger) will be a concern this afternoon/evening.

As these storms track east later this afternoon/evening, they will
be tapping into a better environment (better low-level moisture, and
increased instability) that could support strong to severe storms.
CAMs this morning favor storms becoming more linear as they reach
the eastern plains, closer to Logan/Washington counties. Outflow
gusts of 60-70 mph are possible, with a lower threat for hail. SPC
upgraded portions of the eastern plains to a Slight Risk (2/5)
for this reason.

Tuesday will be similar, with hot temperatures in the mid/upper 90s
and high-based showers and thunderstorms in the afternoon. However,
instability does not look as favorable, so only expecting outflow
gusts up to 35 mph with isolated stronger. We should see a bit
more storms having rain reach the ground due continued increase in
mid- level moisture. Guidance has this mostly confined to the
mountains and high valleys due to better moisture availability.

By Wednesday, the upper level ridge will weaken and shift east as
a weak shortwave embedded in the flow will traverse the region
Wednesday evening/night. Southwest flow aloft will advect
monsoonal moisture into the region, where our mountains will
receive more widespread showers and thunderstorms. For the
plains, scattered showers/thunderstorms will occur, with the
possibility of some becoming strong-to-severe, particularly for
the eastern plains. Modeled Skew-T soundings show very favorable
shear profiles, with decent instability. SPC introduced a Slight
Risk (2/5) for this reason, which seems reasonable at this time.
Steep low/mid-level lapse rates will support strong outflow winds,
however there is also a hail threat. Precipitable water values
are expected to get up to 1- 1.3", so any strong storm has the
ability to produce localized flooding concerns. Storm motion
should be fast, so widespread flooding will not be a concern as of
right now.

For Thursday, more monsoonal moisture will arrive, with precipitable
water values increasing to 120-170% of normal. The upper level
shortwave will continue to trek across Colorado Thursday morning,
providing lift needed to generate more widespread beneficial
rainfall for the plains. Modeled soundings depict a favorable
profile for efficient precipitation (above average PWAT, deep warm
cloud layer, moist vertical profile) thus there is a higher
threat for flooding. WPC has a Slight Risk for excessive rainfall
for much of the mountains, I-25 Corridor, and plains for this
reason.

Friday and into the weekend, ensemble guidance continues to look
promising in keeping the upper level ridge out our southeast.
This will keep us relatively cool (highs in the 80s) with daily
chances of afternoon showers and thunderstorms.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1142 AM MDT Mon Aug 10 2026

Latest radar scans show some weak showers have started to move off
the foothills early this afternoon. So far, no microbursts or
significant outflows have been observed. This is expected to
change in the next few hours as instability increases and DCAPE
values gradually increase as well. While the best timing for
gusty outflows/microbursts continues to be from 21Z to 1Z, there
is still a nonzero chance for this to occur slightly sooner, and
continue through 1Z to 2Z this evening. Strong to severe storms
will be possible over the northeastern corner of Colorado this
evening that may send some easterly outflows towards the TAF sites
which may delay the southward wind transition, but exact timing
and location of said storms will heavily determine the wind
direction. Due to low confidence in these two things, have not
accounted for them in the current TAF, but there could be a few
hours of variable winds before the southerly winds take hold for
the overnight hours.

Smoke has not cleared out nearly as much as anticipated this
morning, so FU has been reintroduced to the TAF for the remainder
of the day. Guidance continues to show this diminishing but with
how much smoke is currently out there, we do expect slant range
visibility to be impacted while the heavier concentrations
persist.

For tomorrow, expecting a fairly normal diurnal wind pattern
through the morning, with drainage winds becoming light and
variable for a few hours before turning to the NE by around
17Z-18Z before returning to the north due to potential showers
passing across Larimer/Weld Counties. A PROB30 has been introduced
for potential for gusty outflows from passing showers by 21Z.

&&

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

&&

$$

DISCUSSION...MAI
AVIATION...9

NWS BOU Office Area Forecast Discussion