Heavy Snow and Winter Weather in Alaska, December 6 to 12, 2022

Name: Heavy Snow and Winter Weather in Alaska, December 6 to 12, 2022
Start: 2022-12-06T04:15
End: 2022-12-12T21:00
Location: Alaska

December 6 to 12, 2022 · NWS AFC · 9 events in 6 counties and zones

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 9

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.

What happened

The episode as NWS AFC wrote it up.

Three back-to-back snowstorms impacted Southcentral and, to a lesser degree, Southwest Alaska over the course of an 11-day window in early December. These snowfall events resulted in particularly significant impacts to the Matanuska-Susitna Borough and Anchorage Borough areas. These conditions occurred as a highly amplified and transitory pattern affected Southern Alaska, bringing 3 to 5 feet of snow to the Matanuska-Susitna and Anchorage Boroughs within the December 5 to 15, 2022 window.

There were a number of commonalities between the three snow events as follows:

1. All snowstorms occurred as a result of frontogenetically induced lift and associated banded snow.

2. All snowstorms occurred in conjunction with a mature trough, indicating increased instability associated with the pattern.

3. All snowstorms were reinforced by some version of an atmospheric river feeding the system.

4. All snowstorms were associated with a weak surface low. More frequently during the winter months, strong lows and associated wind fields produce upslope/downslope effects which tend to limit widespread heavy precipitation to the Gulf coast areas. In this case, winds crossing the mountains were generally weak, which allowed for a particularly long period of snow west of the Kenai and Chugach Mountains. | |It is uncommon to see three storms in a row with such similar characteristics.

In all cases, these ingredients came together to produce abundant snowfall, with the heaviest snowfall generally falling across the higher elevations. The three events occurred December 6-7, 2022, December 11-12, 2022, and December 14-15, 2022, resulting in 3 to 5 feet of snow total over the course 11-day period. Periods of light snowfall in between these dates were noted, but did not have a meaningful impact on snow totals.

These snowfall events hit a few records. For instance, in the city of Anchorage, they hit the 14th highest snowfall amount for a 2-day period December 11-12, 2022 with 16.2 inches of snow. More notably, the only other 11-day period to see higher amounts on record was in 1996 with 44.6 inches, while this 11-day period measured 41.1 inches of snow. To put this event in perspective, these systems pushed Anchorage to the third snowiest snow-year to date and within six tenths of an inch of the snowiest December on record as of December 16, 2022.

What forecasters said that day

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 Anchorage, AK wrote its last area forecast discussion before the first event at Dec 5, 4:43 PM AKST, 11 hours 32 minutes earlier.

Area forecast discussion, Dec 5, 4:43 PM AKST, 11 hours 32 minutes before

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
443 PM AKST Mon Dec 5 2022

.ANALYSIS AND UPPER LEVELS...

A broad area of low pressure is centered north of the Kamchatka
Peninsula with several shortwaves moving across the western and
central Bering and Aleutians. These features are producing small
areas of gales with rain and snow showers. A fairly strong front
is pushing across the eastern Bering and into Southwest Alaska.
This front is producing winds up to 35 to 45 knots across the
AKPen and coastal areas of the southwest. Rain was also reported
along the front across the Pribilofs, the AKPen, and the eastern
Aleutians with temperatures in the upper 30s to low 40s. Farther
east another front extending from Kodiak Island and northward
through the Kenai Peninsula and into Southcentral is making its
way eastward. This front is producing light snow across the Kenai
Peninsula northward towards Anchorage and the Mat-Su valleys.
Rain has been reported near this front at Kodiak City and around
Kachemak Bay with warmer temperatures near the coast. Finally,
the ridge that has been over the area has moved east near the
ALCAN border.

&&

.MODEL DISCUSSION...

Guidance is in good agreement with the large scale features,
however it continues to struggle with the front and triple point
low forming across the Gulf on Tuesday. Some models show the
strongest dynamics over the Gulf with a stronger surface low
near the central Gulf with only weak shortwaves moving inland.
While other models show a weaker low over the northern Gulf and
more dynamics moving inland. The main forecast challenge for
today will be the transition of sleet to all snow across the
Anchorage area, and the location of heavier snow bands and snow
amounts across Southcentral on Tuesday and Wednesday morning.

&&

.AVIATION...
PANC...IFR will lift to MVFR conditions this evening as snow will
taper off tonight with periods of flurries or light snow through
tomorrow morning with accumulations of a half inch or less
overnight. Snow is expected to increase in intensity tomorrow
afternoon, so expect IFR conditions for most of the day tomorrow.
Otherwise light northerly winds today becoming variable tonight.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2:
Monday afternoon through Wednesday afternoon)...

The first round of snowfall for Southcentral has moved through
today. While light snowfall will continue through the evening, it
should lighten up across most locations, and even a brief break
can be expected during the overnight hours tonight. Additional
snowfall is expected tomorrow as an upper level trough arrives to
Southcentral and continues to "dig" south and east, spreading snow
from west to east. While the models have shown better agreement
at 500 mb with the synoptic features, there is still a lot of
uncertainty with regard to the surface features with this event.
Thus, there is lower confidence in expected snowfall amounts,
particularly for the Tuesday into Wednesday timeframe.
Additionally, one complicating factor is the chance for a
deformation band to setup over Southcentral sometime Tuesday
evening. If this occurs, this feature would produce localized
heavier bursts of snow over a short period of time. Current
thinking is that there is a good chance for this feature to set
up over the Cook Inlet region, possibly extending from the
northern Kenai Peninsula through southern Susitna Valley, however
nailing down the exact location of where this heavier band will
setup is quite difficult. Meanwhile, Gulf coastal locations will
likely see a rain/snow mix on Tuesday, or mostly rain as
temperatures will remain warmer for Tuesday in those locations.

As far as the duration of this event, it does appear that
snowfall will linger a bit longer than previously anticipated,
with models now suggesting lingering snow showers through
Wednesday afternoon. There is higher confidence of this occurring
at higher elevations where upsloping is favorable.

As this upper level trough tracks eastward late Wednesday night,
expect a return of cold air and gusty northerly winds for the end
of the workweek.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...

The front stretching from a low near the Gulf of Anadyr is
continuing to move east along the Alaska Peninsula and inland
Southwest. Cold air is expected to advect from the west behind the
front and temperatures will trend cooler over the next few days.
Another weak shortwave will follow closely behind tomorrow morning
bring another wave of precipitation and gusty winds along the
coast and into Bristol Bay. Winds and precipitation will decrease
for Wednesday as a ridge builds from the west and flow will
predominantly be from the northwest.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...

Westerly flow across the Bering Sea and Aleutians will continue
through Tuesday night. Low end gale force winds were observed with
the scatterometer pass this afternoon. With a low near the Gulf
of Anadyr and a front through Southwest Alaska, much of the Bering
Sea and Aleutians are under more conditionally unstable airmass
with cumulus clouds and multiple shortwaves moving from west to
east. Winds, however, are expected to gradually decrease through
Tuesday night. A flattened ridge is expected to build over the
Aleutians Tuesday and spread eastward through Wednesday when a
North Pacific low moves toward the Aleutians. The low progression
appears to weaken as it moves northeast and the gale force,
easterly winds appear to be either be less likely or delayed.
There is some east-west disagreement in the models that could
affect where the precipitation, QPF, and strongest winds will
occur.

&&

.LONG TERM FORECAST (Days 4 through 7: Friday through Monday)...

Long term model guidance continues to show significant
discrepancies with placement of key synoptic features over the
weekend. Ensembles are initially in somewhat good agreement to
start the day 4 period on Friday. Weak ridge of high pressure will
be making its way into Southwest Alaska from the eastern Bering
while a trough of low pressure over the eastern Gulf of Alaska
slowly exits the region to the southeast. Thus average to above
average confidence exists in decreasing precipitation over
Southcentral along with decreasing temperatures over Southcentral
on Friday. This should also see any precipitation over the Bering
and Southwest also diminish on Friday with temperatures from the
Aleutians into Southwest remaining generally unchanged.

Saturday into Sunday is where confidence begins to drop off more
dramatically. The GFS ensemble brings a developing low across the
Aleutians, much further south than the EC, while amplifying a
ridge into Southeast Alaska. The EC ensemble paints a less
amplified pattern, with a weaker trough skirting the Aleutians and
a weaker ridge of high pressure over the Gulf of Alaska. The
implications being much stronger northerly flow with the GFS and
the potential for widespread gales through the Aleutians, Alaska
Peninsula and into the Gulf of Alaska by Sunday. The EC would
promote milder winds over the Aleutians on Saturday, but does
agree on enhanced drainage winds into the Gulf of Alaska on Sunday
as low pressure begins to build offshore of Southeast Alaska.
Ultimately, both ensembles have a more amplified trough building
into the eastern Gulf of Alaska by Monday with high pressure
ridging into the Central Aleutians.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Flood Advisory 155.
MARINE...Gale 130 131 132 150-165 173 175 177-179 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...RC
SOUTHCENTRAL ALASKA...KO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...VR
LONG TERM...BL

Event by event

5 heavy snow, 4 winter weather. Local standard time, as filed.

Winter Weather, Anchorage Muni to Bird Creek

When: December 6, 4:15 AM AKST to December 7, 4:00 PM AKST
Where: Anchorage Muni to Bird Creek forecast zone
Reported by: Trained Spotter

Snowfall event 1 of 3 had quite a few impacts to the greater Anchorage area. Most of the heavier snowfall occurred during the afternoon of 12/6/22. Snowfall rates were consistently 1 inch/hour at WFO Anchorage based on measurements (0-6z 12/7 Snowfall of 6.5 in was recorded).

Highest snowfall reports from a combination of spotters, NWS employees and the public ranged between about 10 to 13 inches on the west side of Anchorage to as much as 2 feet out towards the east Anchorage Hillside. Anchorage police dispatchers had reports of 143 vehicles that had slid or gotten stuck on snowy roads between midnight and 1pm Wednesday 12/7. Four accidents were reported. None of them involved injuries.

The Anchorage and Mat-Su Borough school districts decided early Wednesday 12/7 to close schools for the day. After-school activities were also canceled. The University of Alaska Anchorage and Alaska Pacific University also closed on 12/7.

Power outages in Anchorage also occurred and were focused towards the southern areas of of town on the morning of 12/7.

Winter Weather, Kenai Peninsula

When: December 6, 4:15 AM AKST to December 7, 12:00 PM AKST
Where: Kenai Peninsula forecast zone
Reported by: Public

Public report of an estimated 6 inches of snow was received from Soldotna between about 2 and 5 PM AKST 12/6/22. As much as 9 inches of snow fell across portions of the western Kenai Peninsula between 12/6 and 12/7, mainly focused across higher elevations near the Kenai Mountains.

Winter Weather, Matanuska Valley

When: December 6, 3:00 PM AKST to December 7, 4:00 PM AKST
Where: Matanuska Valley forecast zone
Reported by: Trained Spotter

Most of the heavier snowfall fell between the evening of 12/6/22 and the morning of 12/7. Storm total snowfall reports from public, spotters and NWS employees ranged from about 10 inches to 16 inches across the Matanuska Valley, with the highest amounts focused between Big Lake and Wasilla. The Big Lake, Wasilla, Goat Creek, and Knik River areas were hit with numerous power outages in connection with the heavy snowfall on the morning of 12/7.

Winter Weather, Kuskokwim Delta

When: December 8, 3:13 PM AKST to December 10, 9:01 AM AKST
Where: Kuskokwim Delta forecast zone
Reported by: AWOS

A low pressure system moving up into the Yukon-Kuskokwim Delta produced light snow and gusty southeast winds as it moved onshore between 12/9/22 and 12/10. The Kipnuk AWOS reported several hours of blowing snow and half mile visibility during the late overnight of 12/9 with southeast winds gusting as high as 50 mph.

Heavy Snow, Kenai Peninsula

When: December 10, 3:36 PM AKST to December 12, 9:00 AM AKST
Where: Kenai Peninsula forecast zone
Reported by: Trained Spotter

Spotter report of a measured 24 inches of new snow within a 24 hour period were received from Soldotna; the snow feel between the 11th and 12th.

Heavy Snow, Anchorage Muni to Bird Creek

When: December 10, 8:16 PM AKST to December 12, 9:00 AM AKST
Where: Anchorage Muni to Bird Creek forecast zone
Reported by: Trained Spotter

A second round of heavy snow occurred on December 11 through 12 resulting in 1 to 2 feet of snow across the Borough. New snow reports ranged from 12 to 24 inches, with the verifying observation coming in from the Anchorage Hillside with 24 inches of new snow measured within a 24 hour period.

Heavy Snow, Matanuska Valley

When: December 10, 8:16 PM AKST to December 12, 12:12 PM AKST
Where: Matanuska Valley forecast zone
Reported by: Trained Spotter

The second round of heavy snow occurred on December 11 through 12 resulting in 1 to 2 feet of snow across the Borough. Reports of snowfall measured ranged from 12 to 24 inches across the Matanuska Valley. The verifying report came in from Palmer with 24 inches of new snow measured within 24 hours.

Heavy Snow, Copper River Basin

When: December 10, 8:16 PM AKST to December 12, 9:00 PM AKST
Where: Copper River Basin forecast zone
Reported by: Trained Spotter

Heavy snow occurred on December 11 through 12 resulting in 1 to 2.5 feet of snow across the western portion of the Copper River Basin. The verifying observation was reported by trained spotter in Chickaloon, with 30 inches measured within a 24 hour period.

Heavy Snow, Susitna Valley

When: December 10, 8:16 PM AKST to December 12, 9:00 AM AKST
Where: Susitna Valley forecast zone
Reported by: Public

Heavy snow occurred on December 11 through 12 resulting in about a foot of snow across the southern portion of the Susitna Valley over a 24 hour period. Nearby observations include the Alexander Lake SNOTEL which recorded about 10 of snowfall measured, a |CoCoRaHS which showed 7.0 in Trapper Creek and another recording 6.3 in Talkeetna.

What these are

Winter Weather: Snow, sleet or freezing rain below warning levels that still caused disruption, damage or casualties.
Heavy Snow: Snowfall reaching the local warning threshold without the other hazards of a winter storm.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Alaska in 2022 Every state in 2022 This day in weather history Warnings in Alaska, December 2022

Sources

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: 1095013, 1095966, 1095967, 1097460, 1098710, 1098711, 1098712, 1098713, 1098715.