471
FXUS65 KBOU 061956
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
156 PM MDT Sat Sep 6 2025

.KEY MESSAGES...

- Still hazy/smoky through this evening.

- Better chance for storms across the plains Sunday. A couple
  storms could be strong/severe over the far eastern plains.

- Isolated to scattered showers and storms most days this
  upcoming week but mainly over the higher terrain.

- Warmer for much of the week ahead, but chances of storms may
  increase along with cooler temperatures by the end of the week.

&&

.DISCUSSION /Through Saturday/...
Issued at 156 PM MDT Sat Sep 6 2025

Water vapor satellite imagery showing a shortwave trough tracking
across Utah with scattered/numerous showers and thunderstorms
over eastern Utah and western Colorado. As the shortwave tracks
northeast eastward it shears out some, losing some lift. In
addition to this, the airmass is more stable and drier across
eastern Colorado. This leads to the best chance for showers and
thunderstorms to be over the higher terrain. As the showers move
off the higher terrain, they are expected to be short lived as
they run into a more stable/capped airmass. With the shortwave
moving through the eastern part of Colorado tonight, can`t rule
out a few light showers.

For Sunday, flow aloft turns more westerly and is expected to
help decrease the amount of smoke in the air. Isolated/scattered
showers and storms are expected throughout the area Sunday.
Moisture and instability remains limited, resulting in mainly weak
showers and storms. A lee-side trough/dry line sets up over far
eastern Colorado. Better moisture will reside east of the surface
trough with dew points in the upper 50s. A few of the storms, may
be strong and can`t rule out a couple severe storms as well over
far eastern Colorado.

The upper level ridge that`s been off to our west slides east
across the Central Rockies Monday and Monday night. This is
expected to bring warmer and drier conditions with a slight chance
for a few weak showers and storms over the higher terrain.

Flow aloft turns southwesterly as the ridge pushes east of the
Central Rockies. Still a fair amount of uncertainty on how much
subtropical moisture gets pulled northward by the southwest flow
aloft. Looks to be enough for at least isolated/scattered showers
and thunderstorms each afternoon/evening, mainly focused over the
higher terrain.

For Friday and Saturday, models are hinting at general
troughiness over the western part of the country. This expected to
lead to slightly cooler temperatures and better chances for
showers and thunderstorms.

&&

.AVIATION /18Z TAFS through 18Z Sunday/...
Issued at 1136 AM MDT Sat Sep 6 2025

VFR to prevail through tonight and Sunday. However, smoke is
still expected to reduce slant approach visibilities through today
with some improvement expected Sunday. Scattered
showers/thunderstorms are expected over the mountains, but as they
track eastward off the higher terrain, they will struggle to
survive. Chances for a thunderstorm at DEN is low, 10-15 percent.

Wind direction forecast is expected to become very challenging
after 18Z as a Denver Cyclone forms. Expect winds to become a
northeast direction once the cyclone becomes more established. In
addition to this, outflow winds from the showers/storms to the
west may produce a wind shift or two as well, adding to the wind
direction uncertainty.

For Sunday, HRRR smoke model indicates the amount of smoke in the
Denver area decreases. Difficult to tell if it will be enough of
a smoke reduction for visual approaches. There will be a better
chance for thunderstorms across the plains and added a PROB30 for
thunderstorms after 21Z Sunday.

&&

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

&&

$$

DISCUSSION...Meier
AVIATION...Meier