Fort Logan, Colorado Weather Forecast Discussion

788
FXUS65 KBOU 291120
AFDBOU
Area Forecast Discussion
National Weather Service Denver/Boulder CO
520 AM MDT Mon Sep 29 2025
.KEY MESSAGES...
- Scattered showers and thunderstorms this afternoon and early
  evening.
- Isolated weak showers and thunderstorms Tuesday PM.
- Temperatures will remain above normal through Friday.
&&
.DISCUSSION /Through Sunday/...
Issued at 231 PM MDT Sun Sep 28 2025
The upper-level closed low centered over the Desert Southwest has
made a slow eastward progression since yesterday, now residing
over western Arizona, as evident in satellite water vapor imagery.
The slight eastward movement has allowed subtropical moisture to
migrate a little farther north and east into our higher terrain
today as expected. Instability is already sufficient for
scattered afternoon showers and weak storms as we are already
seeing some develop over the higher elevations. These will be
capable of producing some brief heavy rainfall, small hail, and
gusty outflow winds to around 40 mph in the strongest storms.
Additionally, a shear zone associated with a Denver Cyclone is in
place, and will potentially help initiate things along the Palmer
Divide. Anything that forms there would move northward, along the
urban corridor. The question is if things will hold together in
the lower elevations considering things are still pretty stable
off the terrain. The main impacts from anything that makes it off
the terrain would be gusty outflows as these would be high-based,
and DCAPE values are expected to be between 800 to 1000 J/kg. With
some extra cloud cover expected tonight, temperatures should be a
few degrees warmer than what we saw last night.
The long term portion of the forecast remains largely unchanged. The
low over the southwest is still on track to transition to an open
wave as it finally ejects over the Four Corners and across
Colorado tomorrow. This is still expected to be our best shot at
seeing some precipitation over the lower elevations, as QG
forcings will be greatest as it passes across the region. MLCAPE
values up to 1000 J/kg are portrayed in some hi-res solutions,
making the potential for some thunderstorms greater than what we
are seeing today. While we could see some brief heavy rainfall,
gusty winds, and small hail with the stronger cells, anything
severe is not anticipated.
Outside of some scattered afternoon showers/weak storms over the
highest elevations on Tuesday, things are expected to be mild and
dry across the forecast area for the majority of the week, with
temperatures running slightly above normal under a general zonal
flow pattern aloft. Temperatures will gradually warm through the
week, with the plains seeing mid to upper 80s by Thursday, which
is expected to be the warmest day of the week.
Ensembles still show things start to transition around
Thursday/Friday with increasing southwesterly flow aloft making
its way into Colorado ahead of the next upper-level trough
entering the Pacific Northwest. We still have some time to see how
things play out and allow for ensembles to come into better
agreement, but for now, we can expect some increasing moisture and
cooler temperatures by next weekend.
&&
.AVIATION /12Z TAFS through 12Z Tuesday/...
Issued at 520 AM MDT Mon Sep 29 2025
VFR through the TAF period. Southerly drainage winds are expected
to prevail through about 15Z Monday. Winds then become variable
as they transition to the northeast or east by early afternoon
(19Z) then east to southeast later in the afternoon (22Z). An
upper level system will bring increasing high clouds this morning
and then help trigger scattered showers and thunderstorms this
afternoon, after 20-21Z. The PROB30 for this still looks on
track for the Denver airports.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Bonner
AVIATION...Meier

NWS BOU Office Area Forecast Discussion