707
FXUS65 KBOU 230320
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
820 PM MST Fri Nov 22 2024

.KEY MESSAGES...

- Dry with well above normal temperatures Saturday.

- Mountain snow and a rain and snow mix for the plains late
  Sunday into Monday morning.

- Mountain snow Tuesday through Thanksgiving morning, with
  widespread travel impacts likely.

- Snow may spread into the urban corridor and plains Tuesday
  night/Wednesday morning.

&&

.UPDATE...
Issued at 814 PM MST Fri Nov 22 2024

Our wave cloud is holding strong and there`s plenty of moisture
upstream. There may be a little decrease in moisture later tonight
and a bit more amplitude to the wave that could bring it back to
being focused on the Front Range rather than spreading downstream.
Or it may just be there to stay. Only change to the forecast at
this hour was more cloud cover. Forecast lows look alright. The
cold pools are shrinking and moderating but they`re still there.
It`s getting really warm for this time of year in areas that have
had some mixing. Average low for Denver on this date is 24, and
for Dillon is 9. We`ll be 10 to 15 degrees warmer than that
tonight.

&&

.SHORT TERM /Through Saturday/...
Issued at 214 PM MST Fri Nov 22 2024

GOES 18 Day Land Cloud RGB displays our mountain wave cloud breaking
in a few parts of the urban corridor. This will finally allow for
some additional heating before sunset for those areas west of the I-
25 corridor. Light northwest to west flow aloft prevails due to our
upper level ridge pattern. Tonight, surface winds remain light
across the forecast area. 500mb heights across the GFS and ECMWF
agree on tighter pressure gradients starting late Saturday
morning through Saturday afternoon as the incoming shortwave
enters western. This will increase southwest winds at the surface
for parts of Jackson and Larimer counties where wind gusts up to
30 mph could occur. With light snow on the ground, fire weather
concerns remain minimal. 700mb temperatures between 6-9C will
lead to a few warm spots Saturday afternoon but cloud cover will
limit warming similar to the last few days. Partly cloudy skies
are expected Saturday with the exception of areas south of I-70
mainly in Park and Summit counties. Dry conditions continue
Saturday.

&&

.LONG TERM /Saturday night through Friday/...
Issued at 214 PM MST Fri Nov 22 2024

Flow aloft turns westerly Sunday as a positively tilted upper
level trough tracks across the Northern Plains. The tail end of
the trough and left exit region of the jet is expected to bring
snow showers to the mountains Sunday and Sunday night. Cross
sections indicate the airmass is slow to saturate Sunday and
doesn`t moisten up until late in the day. Snowfall will mainly be
less than 6 inches in the mountains. Enough snow to make roads
snow covered and slippery in places Sunday night and Monday
morning.

At the surface weak high pressure builds in from the north,
creating an easterly upslope low Sunday and Sunday night. This
will usher in cooler air for Sunday. As the easterly winds
increase late Sunday, low level convergence increases leading to
weak lift. This is expected to bring light snow to the urban
corridor and eastern plains Sunday night. Models in fairly good
agreement keeping snowfall light (less than 2 inches) across the
lower elevations. Still can`t rule out a few slick spots for the
Monday morning commute, but overall impacts are expected to be
low.

Strong westerly flow aloft to prevail Monday through Wednesday.
Weak ridging embedded in the westerly flow will bring dry
conditions to the area Monday, Monday night, and into Tuesday. As
the ridge slides off to the east, better moisture and lift returns
to the mountains during the day Tuesday. Snow develops over the
mountains during the day Tuesday and continues Tuesday night. An
upper level trough moves into the Great Basin Wednesday, adding to
the lift. Models continue to trend towards snow spreading on the
urban corridor Wednesday due lift from the trough. Will trend PoPs
upward through out the area Tuesday through Wednesday night as
models slowly come into better agreement that we will see snow
leading up to Thanksgiving.

For Thanksgiving and Friday, models showing a dry and cool
northwest flow aloft across the Central Rockies. Temperatures are
expected to be below normal under this pattern with highs in the
upper 30s to lower 40s across northeast Colorado. However, if the
ground is snow covered, expected cooler temperatures than this.

&&

.AVIATION /00Z TAFS through 00Z Sunday/...
Issued at 513 PM MST Fri Nov 22 2024

VFR through Saturday. South winds around 10 knots at KDEN/KAPA
overnight, then light and variable with a tendency towards east
after 18z-20z Saturday. KBJC winds light.

&&

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

&&

$$

UPDATE...Gimmestad
SHORT TERM...AD
LONG TERM...Meier
AVIATION...Gimmestad