305
FXUS65 KBOU 261740
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1140 AM MDT Wed Aug 26 2026

.KEY MESSAGES...

- Scattered afternoon/evening thunderstorms expected for theI-25
  Corridor and plains. A few storms could become severe, with
  large hail and strong winds possible.

- Thunderstorm coverage decreases Thursday and Friday with mainly
  isolated high-based showers/storms with gusty winds.

- Temperatures return to the 90s Friday andSaturday across the
  plains.

- Thunderstorm coverage increases for late Saturday and Sunday.

&&

.DISCUSSION /Through Wednesday/...
Issued at 1140 AM MDT Wed Aug 26 2026

An upper level high will be centered over Arizona/NewMexico
today with ridging extending northward all the way to Alberta.
This will lead to a northwest flow aloft over Colorado. Outflow
from thunderstorms last night and thismorning increased low level
moisture but also cooled the airmass. Temperatures are slow to
warm this morning, with 11 AM readings only in the mid to upper
70s. DEN ACARS soundings still show a strong inversion centered
around 700mb. Forecast model soundings show this as well, but they
don`t appear strong enough regarding the inversion. This leads to
a highly uncertain thunderstorm forecast and severe threat for
later today. MLCAPE is still forecasted to climb to 1000-2000 J/kg
along and east of the I-25 corridor. The 0-6km bulk shear reaches
30-40 knots. The 30 knots is borderline for severe storms, but
where we see east to southeast surface winds around 10 knots, the
bulk shear will be closer to 40 knots. This favors areas east of a
line from Fort Collins to DIA for severe storms. Because of the
slower heating, storm development will likely be delayed with late
afternoonand early evening hours being favored. Again, given the
strength of the inversion, the severe thunderstorm threat remains
highly uncertain.

The upper-level high will remain centered to our southeast, but
the ridge axis shifts eastwardover Colorado on Thursday. This
will bring warmer temperatures and some drying. Precipitable water
valuesfall below an inch throughout the area, except for the far
eastern plains. Warmer air aloft, less moisture and instability
will lead to a notable decrease in thunderstorm activity. There
should be enough lingering moisture for isolated high-based
showers and thunderstorms. Any rainfall is expected to be light,
with gusty outflow winds up to 45 mph possible. However, southeast
winds will prevail over far eastern Colorado, helping to preserve
low level moisture. MLCAPE will reach 1000-2000 J/kg with 0-6km
bulk shear of around 40 knots, which would favor severe
thunderstorms. Warmer air aloft may cap convection, though.
Convergence along a boundary is likely needed for storms to
initiallyform, and models generally don`t show this happening.

The high intensifies (slightly) and drifts northeastward for
Friday. Temperatures warm further, with highs expected to reach
the lower to mid 90s across northeast Colorado. Models hint at a
slight increase in moisture, which should fuel a round of
afternoon/evening showers and thunderstorms. Given the warm
temperatures and limited moisture and instability, the
showers/storms are expected to be high-based with gusty outflows
being common.

For the weekend, an upper level trough (eventually strengthening
into a closed low)will track east across the northwest part of
the country. This will push the upper level high east of the
region, with southwest flow aloft developing over Colorado. We`ll
see an increase in monsoon moisture leading to a better chance for
showers and thunderstorms. The very warm air hangs on for
Saturday with lower to mid 90s expected again, but temperatures
will cool to the mid 80s to lower 90s for Sunday.

The weather pattern for next week starts to look like a late
summer/early fall pattern, featuring stronger west to southwest
flow aloft with one or two shortwave troughs passing across the
region. For now, models show enough moisture each day for a round
of showers and thunderstorms. However, wouldn`t be surprised if we
end up with a dry and breezy day due to subsidence behind an
exiting shortwave trough.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 1119 AM MDT Wed Aug 26 2026

Not sure about timing of convection due to capping inversion. It`s
possible tstm development around the area may hold off until after
22z and could linger thru 02z based on latest data. If a stronger
storm were to affect one of the airports (10% chance) brief
visibility down to 1 to 3 miles with ceilings blo 6000 ft would be
possible along with wind gusts to 50 mph along with hail. Tstm
threat should diminish after 02z.

As far as winds, they should trend to the east by 19z and linger
thru the aftn thru 02z. By 02z expect more of a SE direction which
will change to southerly by 04z. Overnight expect SSW winds which
will trend to light WSW by 14z.

&&

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

&&

$$

DISCUSSION...BM
AVIATION...RPK

NWS BOU Office Area Forecast Discussion