178
FXUS65 KBOU 042339
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
539 PM MDT Fri Sep 4 2026

.KEY MESSAGES...

- Remaining warmer than normal through most of next week.

- Isolated to scattered showers expected into Saturday, with a few
  thunderstorms Saturday for the northeast plains.

- Higher coverage of showers/storms expected Sunday into Monday,
  although mostly on the weaker side. Daily shower potential will
  carry into most of next week as well.

&&

.DISCUSSION /Through Friday/...
Issued at 1153 AM MDT Fri Sep 4 2026

Low and behold, there are no big revelations with this afternoon`s
forecast package. As expected, we`re running a few degrees warmer
than yesterday and thus on track for a hot afternoon as highs
climb into the mid 90`s for the lower elevations. Once more,
aircraft-derived profiles show pronounced dry air in place,
ratified by the tongue of dry air aloft evident in water vapor
imagery. We should have a touch more mid-level moisture later
today relative to yesterday, enough for a few isolated high-based
showers mostly initiating off the higher terrain of the southern
Front Range mountains and Palmer Divide, but with a lack of
forcing these will generally fall apart as they transition into
the plains. In any case, some localized gusty outflows as high as
30-40 mph will be possible in their vicinity.

For Saturday, we eek out yet another slight increase in moisture
under southerly flow aloft, resulting in a modest rise in shower
coverage (still largely scattered for the mountains and urban
corridor). Enhanced easterly flow at the surface will support
some moisture advection into the eastern plains, pushing MLCAPE
values into the 750-1,250 J/Kg range by late afternoon, creating
potential for a stronger thunderstorm or two mainly for our
northeast plains. Bulk shear will be capped at around 25-30 kts
however, limiting the severe potential to more marginal
thresholds.

By Sunday and Monday, we do manage to advect more appreciable
subtropical moisture into the region, leading to greater coverage
of showers and storms. Synoptic forcing will remain limited
though, buffering the intensity of such activity. We never quite
lose the influence of the high pressure even with the increase in
moisture, so temperatures will remain warm with highs climbing
above 90F for a majority of the plains and urban corridor.

As we progress through the work week, the ridge looks to flatten
somewhat but its axis also shifts westward over or at least
closer to Colorado, thereby maintaining above-normal temperatures.
At this point, the vast majority of ensemble members (> 85%)
support the continuation of warm temperatures. If the high
pressure can remain relatively flat, we should still maintain
sufficient low and mid- level moisture as it wraps around the
ridge to allow for daily isolated to scattered showers and
thunderstorms across most of the region.

&&

.AVIATION /00Z TAFS through 00Z Sunday/...
Issued at 539 PM MDT Fri Sep 4 2026

Isolated high-based showers have developed over the higher terrain
west and south of Denver. There`s a 20-30% chance a shower moves
over an airport and produces a brief microburst. A wind shift due
to organized outflow, is more likely (~75 percent). We will
continue the PROB30 for showers due to the microburst/wind gust
threat. Winds are expected to settle a southwest to south
direction for the night and Saturday morning. After this, the wind
will become light and turn northerly by 18Z. Will continue with
the PROB30 for variable winds and thunderstorms after 22Z
Saturday. It`s still unclear if there will be enough moisture and
instability for thunderstorms Saturday afternoon/evening, but the
chance is high enough to mention it.

&&

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

&&

$$

DISCUSSION...BRQ
AVIATION...BM

NWS BOU Office Area Forecast Discussion