National Weather Service Forecast Discussion

000
FXUS65 KBOU 212020
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
120 PM MST Fri Jan 21 2022

.SHORT TERM...(This evening through Saturday)
Issued at 120 PM MST Fri Jan 21 2022

Light and at times moderate snow is occurring in many spots
across the area, in particular within the winter weather advisory.
The latest HRRR has backed off snow amounts in zone 39 (Boulder
to west metro Denver), but with cold road temperatures even 1-3"
of snow will cause issues for travel this evening. There are
still good signs pointing to convective instability moving south
along the Front Range later this afternoon and evening, which with
increased snow rates we still expect that could/should make for a
messy rush hour--especially in the foothills above 6,500 feet all
along the Front Range and the west part of the Palmer Divide. The
advisory looks like the right highlight through midnight for now.

Elsewhere a decent snow is possible along the higher elevations of
the Front Range and in the mountains along and south of I-70,
with 2-6" possible through midnight. The Park and Gore Ranges may
only see an inch or two as instability is lacking in that area
and there really isn`t any upslope flow. The northeast plains
won`t see much snow either, because of the downslope flow off the
Cheyenne Ridge, especially eastern Larimer, Weld, and points
eastward. Closer to the terrain of the Palmer Divide may see a
half inch of snow.

Snow should end tonight from north to south, by midnight if not
sooner as the upslope weakens and the trough moves even further
south of us into Arizona. The mountains in Park County and the
Palmer Divide near the El Paso line may hang onto light snow for a
few hours more, but no significant additional accumulation are
expected after midnight.

Any lingering icy/snow covered roads will quickly recover/improve
Saturday morning with no chance of snow, mostly sunny skies, and
much warmer temperatures advected from the northwest. Expect
highs in the 40s for the plains and I-25 urban corridor, with 30s
in the mountains valleys other than North and Middle Parks. It
looks like the inversions will hold strong on Saturday without
much wind to scour out the cold air. Highs will remain in the low
to mid 20s there. Winds will be weak across the area other than
the far northeast plains where west winds 10-20 mph with gusts to
25 mph are expected during the afternoon hours.

.LONG TERM...(Saturday night through Friday)
Issued at 120 PM MST Fri Jan 21 2022

Split weather pattern remains over Colorado through Sunday as a
closed low spins over the Desert Southwest and the main storm
track stays off to the northeast. This will result in mild
temperatures and dry conditions. Highs should climb into the lower
50s over northeast Colorado where the snow has melted off and
above the inversion.

Models are good agreement showing a trough diving south across
the Rockies late Monday and Tuesday. Timing is slightly different,
but not too far off. The center of the trough pushes southeast
over the Four Corners. A cold front associated with this system
pushes south through Colorado sometime Monday. Highs will depend
on the timing of the front, so a fair amount of uncertainty
remains with the temperature forecast for Monday. The highest
snowfall amounts should be west of I-25, along the east slopes of
the Front Range mountains and foothills. Here, upslope flow should
help produce a few more inches. At this time, looks close to
advisory amount snowfall with heaviest amounts being 4-8 inches in
the foothills and mountains. The far eastern plains are expected
to see only a little to no snowfall.

Northwest flow aloft will continue over the Central Rockies
Wednesday through Friday. A few models show a weak trough embedded
in the northeast flow aloft moves across Colorado. Most of the
ensemble members are dry during this period, so will keep PoPs
low, but can`t totally rule out snow during this time frame.
Expect temperatures to be near to slightly below normal under this
northwest flow. Could see a windy day or two as flow aloft
increases.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1035 AM MST Fri Jan 21 2022

The low VIS and CIGs have scattered out this morning from the
terminals. Light winds should shift to north-northeast around
noon, with occasional gusts around 20 kts. Lower CIGs should
follow a few hours later, but generally IFR or better
until/unless a decent snow showers move across the terminals.
First, at DEN, any snow that falls is expected to be light, with
under an inch expected between 3-7 PM. Snow chances drop
significantly after 7 PM but ILS conditions are expected to
continue until early morning Saturday. By sunrise at DEN it
should be VFR with light SSW winds. At BJC and APA, there are
better chances of accumulating snow, from about 2-8 PM. For now,
1-2" are expected but there will be a band of heavier snow that
sets up in the higher elevations west of BJC and APA. If for
whatever reason that band sets up further east, then 3-4" are
possible in that timeframe. Snow chances drop quickly after 8/9 PM
at BJC and APA, and VFR conditions should return before sunrise.

At all the terminals on Saturday, winds should be light and SSW
until early afternoon, then shift to north at under 10 kts.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight MST tonight for COZ035-
036-039.

&&

$$

SHORT TERM...Schlatter
LONG TERM...Meier
AVIATION...Schlatter

NWS BOU Office Area Forecast Discussion