Bluebird Lake Trail, Colorado Weather Forecast Discussion

061
FXUS65 KBOU 230539
AFDBOU
Area Forecast Discussion
National Weather Service Denver/Boulder CO
1139 PM MDT Mon Sep 22 2025
.KEY MESSAGES...
- Numerous showers tonight with scattered evening thunderstorms
  mixed in.
- Widespread rain and mountain snow Tuesday, with travel impacts
  possible on high mountain passes due to slush/snow.
- Turning warmer and drier again for the rest of the week ahead.
&&
.DISCUSSION /Through Monday/...
Issued at 329 PM MDT Mon Sep 22 2025
Current radar shows scattered showers and storms across the high
terrain and northern plains, as moisture is increasing ahead of an
incoming upper level shortwave. Looking at surface observations,
our cold front just entered northern Colorado, with recorded wind
gusts up to 35 mph. Temperatures are about 10-15 degrees cooler
behind the front, so expect a cool down as it continues to travel
south, with breezy northerly winds.
Short and long range guidance are now in better agreement of the
upper level shortwave becoming a closed low and tracking down to
western Colorado tonight - although there are still some
discrepancies on exact track and intensity of the low despite
being just 24-30 hours out. ECMWF still favors a slightly more
westerly track than the GFS and the short range solutions like NAM
and HRRR, which would affect where highest precipitation amounts
will fall this evening and overnight. For now, leaning towards the
shortwave having a slightly more progressive track, with PoPs and
QPF in our grids favoring more precipitation for northern Front
Range mountains and plains.
For tonight, expect widespread showers and storms to continue,
with most areas receiving measurable precipitation by Tuesday
morning. Snow is likely above 10,000 ft., with minimal
accumulation this evening. In addition, there could be a few
strong storms this evening, especially along the eastern plains
where instability has been able to build.
By early Tuesday morning, most guidance has 700-mb winds
increasing as the mid level low shifts east across Central
Colorado, with temperatures reaching down between -1 to +1 deg C
(ECMWF continues to be the warmer solution). With favorable
upsloping, snow levels could lower to 9000 ft. if the colder
solutions verify. However, snow levels will also depend on
precipitation rate, where heavier precipitation could cause levels
to dip as low as 8500 ft. With the increased forecasted QPF
amounts (0.75-1.5" across the high terrain) and this being the
first measurable snowfall event of the season, have opted in for a
Winter Weather Advisory for the mountains, with most impacts
occurring above 9500 ft. Exact snowfall amounts are still
uncertain, but expect 3-8" on the high mountain passes, with up to
a foot of snow or more on our highest peaks. The Tuesday morning
commute will be affected, with slippery road conditions expected
through the afternoon.
For the plains, widespread stratiform rain will continue
throughout the day Tuesday, with guidance agreeing on 0.5-1.5" of
QPF, before diminishing by late evening. With the expected cloud
cover, temperatures should stay in the 50s for highs (or even
lower 50s along the I-25 Corridor). There could also be localized
fog wherever rain persists.
Much drier weather is expected starting Wednesday, as our most
recent storm system exits into the Midwest. An upper level ridge,
and a blocking one at that, will then dominate our weather through
most of the week ahead. This will support a return of sunshine and
warmer temperatures. The next chance of precipitation will likely
hold off until late in the weekend or early next week, and even
that looks like a low chance - only if the blocking ridge weakens
and an upper level low can drift northeast from the Desert
Southwest. Overall, some pretty nice autumn weather Wednesday
through most of this coming weekend.
&&
.AVIATION /06Z TAFS through 06Z Wednesday/...
Issued at 1133 PM MDT Mon Sep 22 2025
Ceilings are a bit messy at the moment, with various amounts of
low and mid-level cloud cover near the terminals. Though nighttime
microphysics satellite imagery is mostly blocked by higher clouds,
there does appear to be some filling in of the mid-level cloud
cover and guidance is in fairly good agreement that MVFR to IFR
cigs will quickly redevelop overnight into Tuesday morning. Fairly
likely that IFR conditions will continue most of Tuesday into
Tuesday evening from both rain/visby impacts and the lower
ceilings. Some uncertainty with the precipitation shield tomorrow,
but can`t rule out some brief RA to +RA though the potential for
TS is low.
Meanwhile, winds are also a little squirrelly tonight, with some
weak WSWerly flow. Again, we should see a shift to the north here
during the overnight hours which will more than likely continue
through the rest of the TAF period.
There should be steady improvement Tuesday evening as rain
diminishes and the stratus deck slowly rises... but MVFR
conditions are still likely through most of Tuesday night into
Wednesday AM.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM MDT Tuesday for COZ033-034.
&&
$$
DISCUSSION...Ideker/Barjenbruch
AVIATION...Hiris

NWS BOU Office Area Forecast Discussion