587
FXUS65 KBOU 222107
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
207 PM MST Wed Jan 22 2025

.KEY MESSAGES...

- Light mountain snow into tomorrow.

- Chilly and breezy through Thursday.

- Another system expected late Friday into Saturday, with
  generally light snow but travel impacts expected ( >70%
  confidence for the mountains, foothills, and I-25 Corridor but
  only 30-40% confidence farther east on the plains of any
  impactful snow.

- Dry weather expected early next week with moderating
  temperatures.

&&

.SHORT TERM /Through Thursday/...
Issued at 207 PM MST Wed Jan 22 2025

The first of two weak upper-level disturbances is currently
traversing northeast Colorado, with a small moisture layer between
650-500 mb helping to maintain light snow showers for the higher
mountain elevations. For the most part, near-surface conditions
are too dry to support precipitation for the lower elevations, but
a few elevated bands may produce a few flakes off the higher
elevations of the northern plains as well as the Palmer Divide
this afternoon, so have introduced slight (15-20%) PoPs.

Light snow aside, north winds will continue to mix down this
afternoon and peak before early evening, with gusts 30-45 mph,
highest in the eastern and northeastern plains. Winds will weaken
through the evening as we begin to decouple. Following today`s
cold advection and partial clearing overnight, temperatures will
be rather cold, with lows mostly in the single digits for the
urban corridor, and below zero in the mountains once again. Some
spots near the base of the foothills and northeast plains, where
breezy conditions may linger, will likely remain in the teens.

The second weak wave dips south into Colorado tomorrow, and should
be just enough to sustain some very light mountain snow showers
for the highest elevations (generally less than today). Overall
it`ll result in almost carbon copy conditions, will breezy north
winds developing in the afternoon in the plains, and similarly
chilly daytime temperatures that will hold fairly steady.

&&

.LONG TERM /Thursday night through Wednesday/...
Issued at 207 PM MST Wed Jan 22 2025

Flat ridging will build across the forecast area Thursday night,
but flow aloft will be strengthening. Cross sections show a
mountain top stable layer, and cross mountain flow component
increasing to around 40-45 knots by early Friday morning. With a
relatively strong gradient as shown in the Sangster wind program
output, would not surprised to see some gusts into the 50-60 mph
range for the wind prone areas of the Front Range Mountains and
Foothills. We think the majority of the snow that could blow has
already blown/drifted, so any impacts will be much less than
yesterday.

For Friday, a backdoor cold front will slip across the plains by
mid day or even a bit earlier, as the next upper level trough
drops south across the Northern Rockies. This trough elongates
into the western U.S. with a piece of stronger energy/closed low
redeveloping near Central California by Saturday. There is very
good ensemble agreement that the majority of our forecast area
sees light snow developing from north to south late Friday into
Friday night as mid level frontogenetic forcing is persistent,
and a weak upslope component develops. We expect this upslope
forcing to be quite weak, however, as the system drops so far away
from the forecast area. But, we`ll still have the F-gen to aid at
least light snowfall. If jet dynamics can get close enough, then a
band of moderate snowfall would still be possible. Temperatures
will certainly be much colder by Friday night and Saturday,
allowing road snow and thus another round of slick travel
conditions. The most favored areas for accumulating snow will be
in/near the mountains, foothills, and I-25 Corridor, but drier low
level air and less forcing farther to the east only means very
light snow or flurries over the eastern plains. Snow should
essentially diminish to flurries and come to an end Saturday night
into early Sunday morning as the upper low continues to
retrograde off the California coast and any mid level forcing/weak
upslope fades away.

We have high confidence (>80%) that we`ll return to dry weather
for early next week. This occurs as a upper level col is
eventually replaced by ridging in between the eastern U.S. trough
and the upper low in that moves slowly through the Desert
Southwest. Ensemble clusters support this trough to stay to our
south and shear, which supports a mainly dry forecast with
temperatures returning to near normal. However, there would be
just a 20% chance that the Desert Southwest low/trough moves far
enough north to provide a second chance of light snow.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 1021 AM MST Wed Jan 22 2025

Gusty N/NNW winds are still expected to gradually expand into the
urban corridor over the next 2-3 hours, although they will be
stronger due east of I-25 and particularly over the plains. Thus,
KDEN is best positioned to experience gusts 24-32 kts this
afternoon, with much lower confidence in any prolonged gusty
winds for KBJC and KAPA, hence the TEMPO groups. Winds will relax
this evening with a turn to W/SW flow under 9 kts. Near midday
Thu, expect shift to increasing W/NW winds.

All terminals will see VFR conditions through the TAF period.

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

&&

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

&&

$$

SHORT TERM...Rodriguez
LONG TERM...Barjenbruch
AVIATION...Rodriguez