A storm system moving northward from the North Pacific sent moisture associated with it over southern Alaska resulting in multiple precipitation type issues and hazardous weather. Arctic air already in place out ahead of the system remained entrenched at the surface.
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 AFC wrote it up.
A storm system moving northward from the North Pacific sent moisture associated with it over southern Alaska resulting in multiple precipitation type issues and hazardous weather. Arctic air already in place out ahead of the system remained entrenched at the surface. As warm air rode overtop the cold air at the surface, this resulted in precipitation type issues for certain areas.
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 19, 6:03 AM AKST, 9 hours 41 minutes earlier.
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 603 AM AKST Sun Dec 19 2021 .ANALYSIS AND UPPER LEVELS... A broad upper-level ridge has its axis moving through southwest Alaska this morning. Out west, a strong 300 mb jet spreads from southwest to northeast across the Bering, which is located in tandem with the upstream region of the ridge. An associated front is pushing eastward through the western and central Aleutians, and southerly flow is bringing warm, moist air from the North Pacific. Thus, rain and gusty gale force winds have been the predominant weather conditions for the Bering and Aleutians. Out east, subsidence ahead of the ridge has been creating low stratus for much of Southcentral. However, a warm front pushing eastward across Southwest and toward Southcentral is briefly lifting the low ceilings at times. This front is also moving in concert with an upper-level jet. Because there is a deep layer of warm air behind the front, there has been a relatively clean transition from snow to rain as it moves eastward. So far, this transition is evident over Southwest as the front is still pushing through this region this morning. && .MODEL DISCUSSION... Overall, the models continue to have good synoptic agreement through the middle of next week. However, disagreement remains in regards to the track and amplitude of a shortwave trough moving over a ridge (over Southcentral) on Tuesday. Currently, the NAM is very progressive and shows the highest wave amplitude and greatest QPF amounts, whereas the GFS has the flattest wave amplitude and lowest QPF amounts. The other model solutions are somewhere between the NAM/GFS solutions. Nonetheless, the track and amplitude of this shortwave will determine which Southcentral areas will end up seeing the most precipitation. The details of this feature will be closely monitored in the subsequent forecast packages. && .AVIATION... PANC...Expect ceilings to hover on the low end MVFR range today with the possibility for ceilings to drop to IFR by tonight. Low ceilings may briefly lift at times through the day as a warm front passes through. Winds are expected to be light and primarily out of the N to NE. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today through Wed morning)... A transient upper-level ridge is building across Southcentral this morning. Given the relatively weak flow both aloft and near the surface, low stratus continues to linger from Cook Inlet to the Mat-Su Valleys and across the Copper River Basin. Although some additional clearing is expected, the bulk of these clouds will be tough to scour out of the lower elevations completely. The challenge today will be whether we see any precipitation squeeze out of this low cloud deck. Guidance is all showing a weak mid- level trough moving over top the ridge from west to east through the day. A developing southwesterly flow ahead of this feature will begin to advect low-level moisture and warmer air aloft over the region, especially across Cook Inlet and the Anchorage Bowl. As the wave passes overhead, it may induce enough lift to allow for flurries, or perhaps some areas of freezing drizzle, from Kenai north to Talkeetna, from late Sunday morning into the evening hours. In fact, the 00z and 12z soundings from Anchorage do reflect a freezing drizzle profile. In addition, forecast soundings from Kenai to Talkeetna also indicate this possibility. Right now, flurries is in the forecast for these locations. However, the possibility of freezing drizzle will have to be closely monitored through the day as it is tough to forecast in advance. The ridge axis crests over the region Sunday night as a vigorous shortwave begins to move over Southwest Alaska. The flow aloft again turns to the west-southwest, allowing more moisture to move over the area from the North Pacific. Temperatures aloft will also warm, with areas along Cook Inlet possible climbing above zero degrees Celsius just as precipitation begins to develop over the area for Monday morning. Given this, locations in the Western Kenai Peninsula, mainly along the Sterling Highway from Anchor Point to Kenai, could see a brief period of a wintry mix of snow/sleet/freezing rain at the onset of precipitation before colder air advects in and the precipitation changes to all snow. For Homer, enough warmer air is expected to advect in the lower levels of atmosphere to push temperatures above freezing and allow for a quick transition to rain. Farther north, the precipitation is expected to be all snow for the Anchorage Bowl and Mat-Su Valleys. The snow, however, is expected to begin as wet snow Monday morning then become more powdery through the afternoon and evening hours as the southwesterly flow transitions to a northwesterly flow and temperatures cool both aloft and at the surface. The challenge to this forecast is snow amount. Usually, low amplitude waves moving over the region from west to east are rather moisture starved due to the blocking nature of the Alaska Range to our west. This shortwave, however, is tapping into a deep fetch of Pacific moisture that is well over the climatological norm (150% to 300% of normal precipitable water) for this time of year. Furthermore, there is more of a southwesterly than westerly component to the flow aloft, which should allow this moisture to move up Cook Inlet and not be inhibited by the Alaska Range to the west. As the upper-level flow becomes northwesterly Monday afternoon and colder air is advected in from the north, snow ratios will increase. This is expected to occur just as omega values, a signal of lift in the atmosphere, over the Anchorage Bowl and Matanuska Valley increase. Thus, snowfall rates are expected to increase from Palmer and along the Glenn Highway to east Anchorage by Monday evening with snow likely continuing through the overnight hours. Snow should eventually come to an end by Tuesday morning as the trough moves east of the area. Snowfall totals are expected to range from 1 to 3 inches across the Western Kenai Peninsula, 2 to 5 inches for the Susitna Valley, and 4 to 8 inches for the Matanuska Valley and Anchorage Bowl. Snow will also overspread the Copper River Basin and eastern Prince William Sound Monday afternoon through Tuesday morning. Snowfall amounts here are expected to range from 2 to 4 inches. Strong cold air advection is expected in the wake of the trough overnight Monday through the day Tuesday with strong gusty winds expected through the typical gaps wind areas (i.e. Seward, Whittier, Valdez, Thompson Pass, Barren Islands area, and Shelikof Strait). && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Sunday through Tuesday)... A warm front continues to push eastward across Southwest this morning. Ahead of the front light snow also continues across the Lower Kuskokwim Valley from Sleetmute to Sparrevohn. Previous snow across Aniak has since transitioned to rain while areas further west have cleared with fog and reduced visibilities being observed from Hooper Bay to Bethel to Dillingham. Through today, precipitation will shift further east and into Southcentral while Southwest experiences a brief period of drier conditions as a shortwave ridge overspreads interior Alaska. A cold front is forecast to move into the Kuskokwim Delta later this evening, eventually spreading southeastward across the remainder of Southwest through Monday. One of the main forecast challenges will be the possibility of light freezing rain for portions of the Lower Kuskokwim Valley. Numerical guidance is suggestive that much of the precipitation associated with the upcoming cold frontal passage tonight into Monday will precede the return of colder temperatures behind the cold front. Thus, freezing rain chances appear limited but not out of the question. The greatest potential for snow will exist on the backside of an upper trough as it translates southeastward from Central Alaska into the northern Gulf coast. As northerly winds redevelop on Tuesday, upslope flow over the west and north faces of the Kuskokwim Mountains will likely experience light to moderate snow on Tuesday. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Sunday through Tuesday)... A broad area of high pressure sits stationary to the south of the Eastern Aleutians and Alaska Peninsula this morning with strong southwesterly flow extending from the North Pacific into the Western Bering. Numerical guidance is in good agreement with the ridge remaining in place through next week with only occasional and temporary breakdowns from passing shortwave disturbances into the northern Bering. The end result will be a pattern change with multiple western Bering lows forecast to impact the Aleutian Chain through next week. For Sunday, widespread southwesterly gales are forecast across the Bering with a chance for storm force winds over zones 178 and 411. Seas over the western and central Bering will exceed 20 feet in most areas. Elevated winds will briefly diminish on Monday as one low pressure system weakens offshore of the Kuskokwim Delta. Meanwhile, the next upper low will be garnering strength over the western Bering. By late Monday night/early Tuesday an intense warm front is forecast to lift across the Aleutians with gale to potential storm force easterly winds. These winds will gradually expand across the western and central Bering while transitioning to a southerly direction as low pressure undergoes significant amplification west of the Aleutians. Rain, heavy at times, can also be anticipated across the Aleutians as ample moisture is drawn northward. && .MARINE (Days 3 through 5: Tuesday through Thursday)... Gulf of Alaska: Forecast confidence has greatly increased for Tuesday, with a deeper surface low crossing the Gulf and moderate to strong cold air advection behind it. This will lead to widespread gale force winds across the Gulf waters, with strong and gusty winds through bays and passes. There is some potential for a period of storm force winds, especially in the Kamishak Bay to Barren Islands corridor. Winds will diminish a bit on Wednesday, but another shot of cold air advection is likely on Thursday, so winds will strengthen again by Thursday - likely reaching gale force in a lot of areas once again. Bering Sea: Another deep low will track into the far western bering Sea on Tuesday. While there is some uncertainty in the track and depth of the low, it looks like a very large system which will impact much of the Bering Sea and Aleutians. The forecast largely indicates widespread gale force winds, but there is good potential for smaller areas of storm force winds - especially along the western Aleutians. Smaller and weaker systems will follow quickly behind the first storm for Wednesday and Thursday. It's too early to nail down the details for these storms, but it looks like they will top out at gale force winds and will affect a much smaller area. && .LONG TERM FORECAST (Days 4 through 7: Wednesday through Saturday)... There is a high degree of ensemble agreement that an Omega Block will extend across the North Pacific during the extended period. The ridge-axis is expected to extend northward from the central North Pacific to over Southwest Alaska. This upper level pattern will then continue to persist for the remainder of the extended period. This will lead to warmer temperatures across Southwest Alaska and the Alaska Peninsula. Temperatures will be cooler across Southcentral when compared to Southwest due to broadscale northwesterly flow to the east of the ridge-axis. Mostly sunny skies will continue across Southcentral due to strong subsidence. This pattern will also allow for cold nights across Southcentral due to clear skies and light winds which will allow for effective radiational cooling. The predominant storm track is expected to extend northeastward across the Bering Sea and into the Bering Strait/Seward Peninsula. This will allow a couple of warm fronts associated with lows to move across Southwest Alaska during this period. The first front will be on Wednesday, second will be on Friday and third will be later on Saturday. There is low forecast confidence at this time with respect to the specifics of weather with these fronts, though temperatures will likely be warm enough across Southwest to see a variety of precipitation-types. Chances for rain will be higher in low-lying coastal areas while snow chances will be higher across interior locations such as the lower Kuskokwim Valley and the higher elevations of the Kuskokwim and Alaska ranges. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...Gale Warning: 170, 173-181, 185, 411-414. FIRE WEATHER...NONE. && SYNOPSIS AND MODEL DISCUSSION...AF SOUTHCENTRAL ALASKA...TM SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...BL MARINE/LONG TERM...ED/SEB
6 winter storm, 2 heavy snow. Local standard time, as filed.
Ted Stevens International Airport reported a period of freezing drizzle between 3-4 PM on the 20th of December. Some spotters in Eagle River called the office and reported between 6 and 8 inches of snow through early December 21st.
Spotters reported between 6 to 8 inches of snow throughout portions of the Matanuska Valley. The 511 Alaska page also reported very difficult road conditions from Big Lake to Sutton.
Multiple reports came in across social media platforms. Most of them mentioned sleet and freezing rain occurring throughout the day on December 19th continuing into the 20th along the Sterling Highway from Kenai/Soldotna south to the Anchor Point area on the western Kenai Peninsula.
One of the people associated with the Department of Highways called the office to report 8 inches of new snow in Thompson Pass in the Copper River Basin.
Sparrevohn weather station in the Lower Kuskokwim Valley reported light freezing drizzle between 2:50 PM and 4 PM on December 22nd.
Bethel ASOS reported freezing rain between 2:52 am and 5:20 AM on December 22nd. ASOS ice sensors reported hourly ice accumulation up to 0.11 inches for the 3:53 am observation on December 22nd. The sensor then went down around 4:20 am but not before reporting another 0.02 inches from 3:53 am to 4:20 am. Trace amounts continued through 5:53 am. Bethel police department reported slushy conditions with problems walking or driving.
King Salmon ASOS reported freezing rain between approximately 7:34 am to 8:20 am with an accumulation of 0.04 inches during this time before changing over to all rain.
As the storm system began to pull away, residual moisture on the back side resulted in some light frozen precipitation in and around the Homer on the 22nd of December. The Homer ASOS reported freezing rain mixed with snow during the afternoon resulting in a trace of ice accumulation.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Alaska in 2021Every state in 2021This day in weather historyWarnings in Alaska, 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: 1002208, 1002209, 1002210, 1002211, 1002212, 1002213, 1002214, 1002215.