Fort Collins, Colorado Weather Forecast Discussion

458
FXUS65 KBOU 202337
AFDBOU
Area Forecast Discussion
National Weather Service Denver/Boulder CO
537 PM MDT Sat Sep 20 2025
.KEY MESSAGES...
- Seasonal temperatures for the weekend, with a chance of diurnal
  showers/storms mainly over the mountains.
- Cold front Monday with a good chance of showers late Monday,
  remaining cool with scattered showers Tuesday. High mountain
  snow likely Monday night into Tuesday.
- Turning warmer and drier again late next week.
&&
.DISCUSSION /Through Saturday/...
Issued at 302 PM MDT Sat Sep 20 2025
Current satellite and radar imagery show convection initiating off
a boundary over the eastern portion of the Palmer Divide and
plains. With the lack of cloud cover allowing instability to
build, hail up to 1" and wind gusts up to 60 mph will be the main
threats for the strongest storms as they travel east. In
addition, scattered high based showers are forming over the Front
Range mountains, but are dissipating as they spill onto the
adjacent plains due to an overall stable environment. Expect
showers and thunderstorms to mostly be confined to the higher
terrain this afternoon, with a few of the stronger storms possibly
spilling onto the adjacent plains. However, short term CAMs do
indicate storms developing off the Cheyenne ridge later this
afternoon and traveling across northern/northeastern Colorado.
With SPC Mesoanalysis showing MUCAPE ~500 J/kg and steep lapse
rates of 9 dg C/km, some of these storms could become sub-
severe/severe, with hail up to 1" and outflow winds up to 60 mph.
Sunday will be our warmest day of the forecast period, with highs
in the low 80s across the plains. With increasing northwest flow
aloft ahead of an incoming system, another round of showers/storms
are possible mainly for the higher terrain. A few showers may
might spill onto the adjacent plains, so have increased PoPs for
Sunday.
Models are still struggling to grasp the trajectory of the upper
level trough that will move into our area late Monday. Short range
solutions suggest the system will have a more easterly track,
while ensemble solutions like the ECMWF and GEFS have continued
to trend with a westerly track. If those solutions verify, we
could have more widespread precipitation late Monday and into
Tuesday. For now, NBM seems to have a good grasp on PoPs, with
increased precipitation chances for the eastern plains Monday
night and Tuesday. With cold air advecting into our region,
elevations above 10K ft. could see snow. In terms of temperatures,
the plains will be in the low-mid 60s on Tuesday, due to a cold
front moving through. Wednesday morning, some of the colder spots
on the the plains could have frost, but most of the area will be
in the low 40s.
After the upper level trough departs, a strong ridge will being to
build, which will bring temperatures back to seasonal normals by
Thursday.
&&
.AVIATION /00Z TAFS through 00Z Monday/...
Issued at 537 PM MDT Sat Sep 20 2025
VFR to prevail through tonight and Sunday. High-based showers to
the west of Denver may bring a wind shift to the west through 03Z.
Additional outflow winds from previous showers and thunderstorms
are tracking towards the Denver area. A boundary from the south
and one from the N/NE are on track to move through DEN 01Z at
their current pace, so 2-3 wind shifts will be possible 01-03Z.
Winds eventually settle a southerly direction for the night around
06Z. Additional high-based showers/thunderstorms with outflow
winds are expected Sunday after 21Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Ideker
AVIATION...Meier

NWS BOU Office Area Forecast Discussion