806
FXUS65 KBOU 092108
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
208 PM MST Sat Nov 9 2024

.KEY MESSAGES...

- Finally quieting down tonight into Sunday.

- Windy Front Range Mountains and foothills tonight into Sunday
  morning and again Tuesday night into Wednesday.

- Chance of mountain snow showers Tuesday and Tuesday night.

&&

.SHORT TERM /Through Sunday/...
Issued at 120 PM MST Sat Nov 9 2024

So, Colorado, that was a week.

Outside of a few lingering showers across the northern
mountains/foothills, there`s not much left of our storm system to
talk about. Across the plains, skies are starting to clear out,
the final snow numbers have been tallied, and roads are starting
to (slowly) reopen. Thankfully, a quiet weather pattern is
returning to the region for Sunday... and may continue all the way
through the upcoming week.

There may be some briefly gusty winds across the higher elevations
tonight, as the flow turns a bit more westerly with some modest
mountain wave amplification possible. We`re generally looking at
peak wind gusts of 40-50 mph though it wouldn`t be surprising if a
couple gustier spots in the higher mountains see some 60 mph gusts
overnight. This should be fairly short lived however, as the flow
weakens by tomorrow.

The upper low will be replaced by some weak ridging by this time
tomorrow, leading to mild temperatures and mostly sunny skies. The
only lingering questions are (1) how much influence does the snow
pack have on temperatures east of Denver, and (2) how much fog
develops tonight and again tomorrow? Models with good snow depth
initialization generally keep temperatures in the 40s across the
deeper snow locations, with low to mid 50s elsewhere. For fog,
guidance is generally bearish on the idea but previous setups with
a very high moisture-content snowpack have outperformed models.
For now have added some patchy fog in the valleys tonight and will
hope the evening shift has some better ideas.

&&

.LONG TERM /Sunday night through Saturday/...
Issued at 120 PM MST Sat Nov 9 2024

The current active pattern looks to take a little break for the
extended forecast period. By Sunday night, westerly flow aloft is
expected to be in place over Colorado, which will allow for
modest mountain wave development. The downslope component will
help keep conditions dry on the lee side of the Rockies, and help
melt some of the recent snowfall, especially in our foothills
locations. Cross sections show a dry airmass remains in place
through Monday, with increasing moisture returning to the high
country ahead of the next approaching trough on Tuesday. Guidance
solutions still show slightly different amplitude and placement of
the passing trough, though the latest GFS has shifted the trough
slightly south, bringing it towards better agreement with the
ECMWF and Canadian solutions. This would bring some light snow to
our mountains Tuesday evening into Wednesday morning. Winds are
expected to increase as cross sections show a near ridgetop
stable layer form by Tuesday morning. Wind gusts between 45-55 mph
will be possible at our highest elevations and eastern slopes of
the Front Range mountains through Wednesday. Enhanced wind gusts
to 40 mph can be expected for our typical windy spots off the
Cheyenne Ridge in northern Larimer and Weld Counties as well
through Wednesday.

Northwesterly flow aloft will develop as the trough pushes eastward
Wednesday. Subsident flow will help keep dry conditions in place as
500mb ridging is expected through roughly Thursday before another
potential trough approaches by the weekend.

With the recent widespread snowfall this weekend, fog development
will be one thing to watch for in the coming days. With light winds
and mostly clear skies expected on Sunday night, conditions will be
favorable for fog to form over our plains, especially the South
Platte River Valley, as well as our mountain valleys that may lower
visibilities for the Monday morning commute. With increasing winds
expected for Tuesday morning, conditions will be less favorable for
fog.

For temperatures, daytime highs are expected to be near normal
through Wednesday before things warm up to above normal once again
on Thursday. Temperatures may fluctuate depending on melting snow
impacts. Have lowered temperatures in areas where heavy snowpack
is present. Especially over Lincoln County.

&&

.AVIATION /18Z TAFS through 18Z Sunday/...
Issued at 1041 AM MST Sat Nov 9 2024

Steadily improving conditions through this afternoon, with VFR
conditions likely after 00z. Varying ceiling heights under the
stratus deck right now, with lower cigs closer to the precip east
of DEN. Ceilings should rise through the afternoon and stratus
should burn off by this evening. A little uncertainty in the exact
timing but we look like we`re on track. There`s an outside chance
at some FG at the terminals tonight and again Sunday afternoon,
but not enough of a concern to include in the TAF right now.

VFR should persist into Sunday with light drainage winds through
most of the period. The exception to that may be BJC where there
could be a temporary push of gusty westerlies overnight tonight.

&&

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

&&

$$

SHORT TERM...Hiris
LONG TERM...Bonner
AVIATION...Hiris