Winter Storm in Alaska, December 28 to 30, 2021

Name: Winter Storm in Alaska, December 28 to 30, 2021
Start: 2021-12-28T04:29
End: 2021-12-30T13:03
Location: Alaska

December 28 to 30, 2021 · NWS AFC · 4 events in 4 counties and zones

A low pressure system moving northward from the North Pacific met up with Arctic cold entrenched over southern Alaska. As a result, moisture from the Gulf spread inland and met up with the Arctic air in place leading to a myriad of winter weather precipitation types.

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 4

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.

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 27, 5:22 PM AKST, 11 hours 7 minutes earlier.

Area forecast discussion, Dec 27, 5:22 PM AKST, 11 hours 7 minutes before

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
522 PM AKST Mon Dec 27 2021

.ANALYSIS AND UPPER LEVELS...

Infrared and water vapor satellite imagery show a strong upper
level ridge in the North Pacific and a stacked low in the
northern Bering. A warm front extends off the Bering low and
stretches across much of Alaska. In the Southwest, rain is slowly
tapering off. Bethel and King Salmon have recorded just over 0.15
inches with the warm front, and this plentiful moisture is
producing fog over much of the Southwest. In Southcentral, fog
that began in the morning has mostly dissipated due to high clouds
moving in ahead of the warm front. Across the Aleutians, broad
southerly flow and warm advection has kept today's highs in the
40s, with temperatures in Unalaska and Adak reaching the 50s. The
advection of warm air aloft with yesterday and today's warm fronts
are apparent in the 00Z soundings for Bethel, King Salmon, and
Anchorage. In particular, the Anchorage sounding features a stout
inversion, with 26 degrees at the surface and 40 degrees at 900
ft.

&&

.MODEL DISCUSSION...

Models remain in good synoptic agreement through the short term.
Model differences are greatest for precipitation timing and
amounts for Tuesday's front. In the Southwest, the GFS keeps the
bulk of precipitation further north in the Kuskokwim Delta. In
contrast, the NAM and Canadian show higher QPF in Bristol Bay.
Tuesday evening, models differ with the timing of embedded
shortwaves entering Southcentral. As a result, the NAM and
Canadian bring precipitation over Southcentral earlier than the
GFS, suggesting higher total QPF and the potential for greater
freezing precipitation.

&&

.AVIATION...

PANC...Fog is likely (and light freezing drizzle is possible)
overnight due to warm air aloft and low-level moisture. Confidence
is high that ceilings will increase to at least MVFR Tuesday
morning as the temperature inversion lifts. However, confidence
with the timing and amount of freezing rain Tuesday afternoon is
low.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through
2/Tonight through Wednesday)...

A shortwave trough is pushing through Southcentral this evening.
Radar returns are filling in across the Anchorage Bowl southward
into the Turnagain Arm. Areas of light freezing drizzle will be
possible into the after-dark hours which will likely result in
slick and icy roadways tonight. Not to be outdone, a second area
of low pressure is forecast to move into Southcentral late Tuesday
with a higher chance of freezing rain across the Matanuska Valley
southward into the Kenai Peninsula. Latest numerical guidance has
trended slightly warmer with upper level temperatures and this
will favor initial precipitation in the form of freezing rain
through early Wednesday morning. Accumulations of up to a tenth of
an inch will be possible with locally higher amounts not out of
the question for the higher elevations, where warmer surface
temperatures may slow the transition to all snow. Cold air
advection will eventually bring a transition to all snow by early
Wednesday morning as low pressure continues eastward and a cold
front cools upper level temperatures over Southcentral. What
previously looked like a more straight forward forecast has
quickly become increasingly complicated with increased uncertainty
in duration of freezing rain as well as total ice accumulations.
We will be updating the forecast with additional information as
the finer details are worked out.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: This
afternoon through Thursday)...

A frontal system moving across the area will continue to produce
valley rain and snow in the higher elevations. This front will
quickly move away this evening with a brief break tonight, however
stratus and fog are likely across most valleys and coastal
locations through Tuesday. A stronger front will move across the
area beginning Tuesday morning bringing more rain to most valleys.
However, interior valleys, especially the lower Kuskokwim River
Valley, will see a wintry mix briefly before changing to all rain.
Winds will also increase from the south with this system with
gusts to 30 to 40 mph at times especially across the Y-K Delta.
Tuesday afternoon and evening a cold front will push inland which
will bring cooler air to the area. There could be a brief mix of
snow, but most of the precipitation will end by the time the cold
air arrives. Wednesday will be a slightly cooler day, but still
above normal for late December as a ridge of high pressure moves
over the area for Tuesday night and Wednesday. A pair of frontal
systems will approach, first on Wednesday afternoon and evening
bringing a rain snow mix to coastal areas of Bristol Bay and
possible farther inland. However, some uncertainty on how far
inland the snow will occur. A second stronger front moves inland
by Thursday bringing a good chance of snow to inland locations and
better chances of rain near the coast.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: This
afternoon through Thursday)...

Several fronts and low pressure systems will move across the area
through the next couple of days producing areas of Gales and
periods of rain. Areas of Gales are expected near a cold front
moving across the Bering through Tuesday. Otherwise a couple of
compact lows will move across the western Aleutians and Bering
through Wednesday producing small areas of Gales near the low. A
stronger low and frontal system will enter the central and eastern
Aleutians late Wednesday and Thursday producing a wider area of
Gales extending into the Bering, especially behind the low and
cold front as cold air enhances the winds on Thursday. The AKPen
will see periods of rain and Gales most of the period, however on
Tuesday night and Wednesday colder air will bring some snow to
the area but generally 1 to 3 inches in populated areas.

&&

.MARINE (Days 3 through 5: Thursday through Saturday)...

Bering...A North Pacific low tracks towards the Pribilofs
Thursday, then enters Southwest Alaska Friday. Winds will be
northerly across most of the Bering, peaking at high-end gales on
the backside of the low. Southerly small crafts are expected
ahead of the low. Starting Friday, a Kamchatka low brings
southerly gales as its front tracks into the Western and Central
Bering. Seas will be mostly 8-15 ft except 15-25 ft where gales
are expected.

Gulf of Alaska...Winds below small crafts and seas below 8 ft
persist through Thursday evening, when a low develops in the Gulf.
Expect widespread small crafts, with a gale-force barrier jet
along the northern Gulf Friday morning. As the low moves
southeast late Friday, cold outflow winds will develop with storm
force winds possible through Kamishak Gap. Seas 8 ft or lower
Thursday will increase to 15-25 ft by late Friday.

&&

.LONG TERM FORECAST (Days 4 through 8: Friday through Monday)...

An upper-level trough moves across the Southern Mainland Friday
through Saturday. Its associated surface low and fronts will
bring widespread precipitation across Southwest Friday,
transitioning to showers late Friday into Saturday. Precipitation
is expected to begin early Friday in Southcentral, tapering off
by late Saturday evening. Currently, mixed precipitation or rain
look likely over Kodiak and parts of the Southwest as 850 mb
temperatures peak just above freezing. In Southcentral,
precipitation is likely to remain snow.

Once precipitation ends, cold and mostly dry conditions are
expected through Monday for the Southern Mainland. A low in the
Gulf and a highly amplified ridge in the Bering Sea will allow for
northerly cold air advection and gusty gap winds. As a Kamchatka
front tracks eastward, it will bring rain across the Aleutians
Friday through Monday and push the ridge eastward into the
Southwest.

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning 120 130-132 138 165 170 172-178 185 351 352
					  411-414.
FIRE WEATHER...NONE.

&&

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

Event by event

4 winter storm. Local standard time, as filed.

Winter Storm, Anchorage Muni to Bird Creek

When: December 28, 4:29 AM AKST to 8:46 PM AKST
Where: Anchorage Muni to Bird Creek forecast zone
Reported by: Official NWS Observations

Ted Stevens International Airport ASOS station recorded light freezing rain beginning at 2:11 PM on the 28th of December and continued through 2:53 PM on the 28th. A trace of ice was recorded. |Another ASOS station in Birchwood reported light snow beginning at 2:38 PM which then changed to sleet or unknown precipitation at 2:56 PM and continued through 8:05 PM on the 28th. Precipitation then switched to rain and then unknown precipitation for a few minutes through 8:35PM on the 28th.|Spotter called the office and mentioned freezing rain in downtown around the same time observed at the office (could hear it on the roof). Another spotter called the office to report that Big Lake had 0.10 inches of ice accumulation and no snow.

Winter Storm, Matanuska Valley

When: December 28, 4:29 AM AKST to 8:46 PM AKST
Where: Matanuska Valley forecast zone
Reported by: AWOS

AWOS observation located at the Parks Highway at Hawk Lane MP53 (HKLA2) reported unknown precipitation and a road temperature of 30-31 F with an air temperature of 33-34 F beginning at 7:10 and continued through 8:10 on the 28th of December.|The Alaska 511 webpage at 5:30 PM on the 28th on the Glenn Highway between MP 29-66 recorded difficult road conditions, ice build-up, ice glaze, as well as wet, and icy roads.

Winter Storm, Kenai Peninsula

When: December 28, 1:04 PM AKST to 8:46 PM AKST
Where: Kenai Peninsula forecast zone
Reported by: NWS Employee

Issued due to a report from an NWS Employee of freezing rain in Kenai. They also said roads were bad, rain was full droplets, and 22 degree air temp.|A spotter called the office and reported solid rain from Kenai to Soldotna to Sterling at approximately 4:35PM on the 28th of December with an air temp 31 degrees and very slick roads. They also reported that the Spur Highway was closed about an hour prior and roads seem to also be sanded. Social media reports of rain & slick surfaces.|The Alaska 511 page reported at 2:35 PM on the 28th that all roads between Kenai, Soldotna, Sterling, and Kasilof River were difficult, black ice, frosted surface, ice, ice glaze, icy patches, road surfaces in poor condition, surface water hazard, wet and icy roads, and freezing rain. Also, social media reports came in of a large power outage effecting many on the Central Peninsula. Social media reports came in that Homer Electric Association was responding to a large power outage effecting over 4,000 members across the Kenai Peninsula and attached the article to the tweet.

Winter Storm, Kuskokwim Delta

When: December 29, 3:24 PM AKST to December 30, 1:03 PM AKST
Where: Kuskokwim Delta forecast zone
Reported by: Official NWS Observations

Toksook Bay ASOS observations reported snow and freezing fog with northeast winds of 26 mph with gusts to 33 mph and visibility of one half mile.|At the peak of the event, Toksook Bay ASOS reported snow and freezing fog with quarter mile visibility with northeast winds of 33 mph and gusts to 44 mph. |Toksook Bay ASOS was down at a half mile or less for 3-5 hours between 11:30 AM and 3 PM on the 29th. Webcams showed bad conditions. ASOS reported quarter mile visibility at 2:27PM on the 29th and was consistently down at a quarter mile or less even zero at times through 6 PM the evening of the 29th. Winds were sustained 35 mph gusting to 42 kts (48 mph).

What these are

Winter Storm: A storm that brought snow, sleet or freezing rain at warning levels, usually over several hours or days.

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

The same day elsewhere

Every storm in Alaska in 2021 Every state in 2021 This day in weather history Warnings in Alaska, December 2021

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: 1007080, 1007081, 1007082, 1007085.