A winter weather system brought moderate to heavy snow over the Palouse, Lewiston-Clarkston Valley, Camas Prairie, and Central Panhandle. The snow came in two waves: first wave in the morning with snow resulting in slippery roads for the morning commute and the second in the early afternoon hours.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS OTX wrote it up.
A winter weather system brought moderate to heavy snow over the Palouse, Lewiston-Clarkston Valley, Camas Prairie, and Central Panhandle. The snow came in two waves: first wave in the morning with snow resulting in slippery roads for the morning commute and the second in the early afternoon hours.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Spokane, WA wrote its last area forecast discussion before the first event at Dec 29, 10:05 PM PST, 2 hours 55 minutes earlier.
Area Forecast Discussion
National Weather Service Spokane WA
1005 PM PST Wed Dec 29 2021
.SYNOPSIS...
Very cold temperatures continue this week. Tonight into Thursday
another winter weather system will bring the potential for
moderate to heavy snow over the Cascades, Palouse, Camas Prairie,
and Central Panhandle. The next system looks to arrive late in the
weekend into early next week, with temperatures returning to
closer to normal starting Sunday.
&&
.UPDATE...
Winter weather advisories have been added for the eastern portion
of the Upper Columbia Basin, Spokane Area and Coeur d'Alene Area
for late tonight through mid afternoon Thursday. Snow is expected
to come in two waves. The first will be this morning with light
snow resulting in slippery roads for the morning commute. The
second will come for the early afternoon hours with a period of
light to moderate snow possible. All other warnings/advisories
already in effect appear to be on track. /SVH
&&
.DISCUSSION...
Tonight through Thursday night: Some low clouds
producing snow flurries have developed in the wake of this
mornings exiting weather disturbance with significant amounts of
sun filtering through the thinner higher cirrus clouds invading
the sky from the north this afternoon. They may linger for a spell
before they diminish and/or exit to the southeast. Otherwise a
persistent northwest flow continues to maintain the cold air in
place over the area as well as steering shortwaves down at times
to bring snowfall. Such a shortwave is expected to drop down for
the next significant snowfall Thursday. Snow to water ratios are
running high and the atmosphere is very cold and shows and
increase in conditional instability which should allow for a very
light and puffy snow. This will increase the snow amounts produced
by the passing shortwave. Winter weather highlights including
warnings and advisories are in place to address this snowfall.
/Pelatti
Friday through Tuesday: Friday will be a brief break between weather
systems with dry conditions moving in behind the southward moving
cold front and with ridging aloft. Temperatures will cool again
on Friday with the return of the northerly flow and breezy north
winds Friday morning. Highs will be in the single digits to low
teens. With skies clearing overnight Friday behind the departing
cold front, Saturday could feature the coldest widespread morning
temperatures of this cold snap. Our current forecast has
widespread temperatures in the negatives. There isn't much
confidence in this since many factors will have to perfect align
for us to cool that significantly, but the NBM is giving a greater
than 60% chance for many locations across the northern Basin into
the Spokane area and the northern valleys to see below 0 lows.
Slight changes in the arrival of the next round of clouds could
make or break this forecast.
The ridge begins to move east late Friday into Saturday morning
ahead of the next system. Weather will be quiet again on Saturday
outside of light snow and flurries associated with moderate warm
air advection. Snow looks to generally be light with less than an
inch of snow accumulation.
The next system is projected to slowly slide down the BC coast move
into the region late in the weekend into early next week. Models
haven't quite come into agreement on the exact position and
progression of this low as it moves down the coast. Therefore, exact
specifics on the related impacts remain fuzzy. Right now, there has
been decent agreement that this low will allow the PNW to return to
a more typical westerly/southwesterly flow aloft and moderate
temperatures back to near normal values. This trough will also
likely be the dominant weather feature through at least the middle
of next week.
Monday into Tuesday, model ensembles are highlighting the potential
for moderate to heavy snowfall across Okanogan Valley into the
Okanogan highlands, northeast Washington mountains, and northern
Idaho mountains. Although still 6 days out with high chances for
multiple changes before then, the NBM is currently giving the
northeast WA and northern ID mountains about an 70% chance to see
greater than 6 inches of snow. Monday also looks to feature
breezy to gusty southerly to southeasterly winds with a strong
surface pressure gradient. While the most impactful winds look to
remain in Oregon and far southern Washington, we could see wind
gusts across the Basin into the Palouse and the Spokane area up to
35 mph. The exact strength and timing will be dependent on the
evolution of the pattern, so confidence isn't very high. However,
with potential for multiple hazards across the region, this will
be the period to keep an eye on as the event gets closer. vmt
&&
.AVIATION...
06Z TAFS: A shortwave trough of lower pressure will drop down over
the region on Thursday. Snow will come in through with two
impulses. Morning snow will be relative light with IFR visibility
at KGEG-KSFF-KCOE-KPUW-KLWS. The second pulse of snow will arrive
in the afternoon. Snow rates are expected to be higher with
periods of moderate to heavy snow low to very low IFR conditions possible
at KPUW and KLWS. Snow will begin to shift out of the region to
the southeast Thursday evening. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 4 16 0 12 -5 17 / 70 70 0 0 0 20
Coeur d'Alene 7 18 4 15 0 20 / 80 70 0 0 0 20
Pullman 7 22 8 14 0 19 / 70 90 20 10 0 20
Lewiston 13 27 18 22 9 25 / 40 90 30 0 0 10
Colville 2 13 -6 12 -8 13 / 60 40 0 0 0 10
Sandpoint 9 17 7 17 3 17 / 70 30 0 0 0 30
Kellogg 8 19 10 16 2 20 / 70 80 20 10 0 30
Moses Lake 7 18 5 17 2 18 / 20 50 0 0 0 10
Wenatchee 8 16 8 16 5 18 / 10 70 10 0 0 10
Omak 2 14 3 12 3 17 / 10 50 0 0 0 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning from 4 AM Thursday to 4 AM PST Friday for
Idaho Palouse.
Winter Weather Advisory from 4 AM Thursday to 10 AM PST Friday
for Central Panhandle Mountains-Lewis and Southern Nez
Perce Counties.
Winter Storm Warning from 7 AM Thursday to 4 AM PST Friday for
Lewiston Area.
Winter Weather Advisory from 2 AM to 3 PM PST Thursday for Coeur
d'Alene Area.
WA...Winter Weather Advisory from 1 AM to 7 PM PST Thursday for
Western Chelan County.
Winter Storm Warning from 4 AM Thursday to 4 AM PST Friday for
Washington Palouse.
Winter Storm Warning from 7 AM Thursday to 4 AM PST Friday for
Lower Garfield and Asotin Counties-Northeast Blue
Mountains.
Winter Weather Advisory from 2 AM to 3 PM PST Thursday for
Spokane Area-Upper Columbia Basin.
&&The national radar mosaic for the moment the first event began.
2 heavy snow. Local standard time, as filed.
Snow began to accumulate at 1000 PST, and tapered off by 1700 PST. A total of 6 to 7 inches of snow fell across the Lewiston Valley. A new record was set, for total snow on December 30th, of 7.2 at the Lewiston Airport.
Snow began to accumulate at 0100 PST, and tapered off to flurries by 1600 PST. A total of 5 to 7 inches of snow fell from Moscow to Potlatch.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2021Every state in 2021This day in weather historyWarnings in Idaho, December 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 997141, 997143.