A north to south oriented frontal boundary brought periods of heavy snow, avalanche conditions, lowered visibilities, high winds and strong surf from west to east over the course of several days as the front shifted slowly east and developed into a triple point low over the western Gulf. Strong upper level dynamics and a deep moisture fetch made this an impactful storm for southern Alaska.
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 north to south oriented frontal boundary brought periods of heavy snow, avalanche conditions, lowered visibilities, high winds and strong surf from west to east over the course of several days as the front shifted slowly east and developed into a triple point low over the western Gulf. Strong upper level dynamics and a deep moisture fetch made this an impactful storm for southern Alaska.
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 3, 5:33 PM AKST, 11 hours 27 minutes earlier.
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 533 PM AKST Fri Dec 3 2021 .ANALYSIS AND UPPER LEVELS... An upper level ridge axis extends across the state from the Beaufort Sea south toward the Alaska Peninsula. Meanwhile, an upper level trough is in place over the northern Bering while a second upper level trough axis extends from the Alaska-Yukon border southward into the eastern Gulf. A front extends from north to south over the western coast of the state. This has produced blizzard conditions across the Kuskokwim Delta Coast with snow and blowing snow observed. Farther east, a persistent stratus layer has remained over the Copper River Basin. Fog and low level stratus also developed along Knik Arm this morning with some fog drifting into the Anchorage Bowl. Farther west, westerly gale force winds persist across the Bering. && .MODEL DISCUSSION... Model solutions are in good agreement through the short term and have been consistent with the arrival of a broad low over the mainland this weekend. Initially, the 12Z NAM painted a very different picture of the 300 mb jet pattern, showing more of a zonal orientation with the jet streak positioned farther eastward over Southcentral. Now with the 18Z NAM run, the solution is more in line with the GFS which has been depicting the jet streak oriented from southwest to northeast positioned over the Alaska Peninsula and not extending over Southcentral as much. Another difference previously observed between the NAM and GFS solution was the location of a triple point low spinning up along the frontal boundary. The GFS has consistently advertised this low developing in the vicinity of Kodiak Island while the NAM placed this low over Prince William Sound. However now that the NAM has fallen in line with the GFS, this has led to increased confidence in the GFS solution. Overall, we remain confident in an active winter weather pattern across the southern half of the state this weekend, however the finer details including snowfall amounts and potential for rain/snow mix in places are still being ironed out. Please stay tuned as we continue to closely monitor this developing situation. && .AVIATION... PANC...Fog and low stratus remain the biggest challenge. Expect low ceilings around the terminal with persistent MVFR to IFR conditions. However, there is potential for fog to develop over the terminal again tonight, reducing conditions to LIFR. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Tonight through Monday)... Light snow showers are developing near western Prince William Sound in response to an upper level wave and associated mesolow moving southeastward across Southcentral. Another mesolow will form near Seward, keeping showers around into the weekend along the northern Gulf coast as well as the offshore marine areas. A cold, dry airmass combined with clear skies will allow overnight temperatures to drop down in the single digits to below zero across the lower and higher elevation regions for tonight. Elsewhere, temperatures will be moderated due to cloud cover sticking around through Saturday morning. Otherwise, benign conditions will prevail as a ridge of high pressure dominates at least through Sunday. As the ridge axis moves east, a broad longwave trough over the Bering Sea will shift over the eastern half of the interior state and bring unsettled weather conditions into early next week. A triple point low will develop along a frontal boundary near the western Gulf and Kodiak Island, with strong winds and moderate to heavy snow for all areas. With strong dynamics and deep moisture fetch, this could be a significant snow event for Southcentral, but specific details in the forecast are still being ironed out. So stay tuned for the latest updates. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Tonight through Monday morning)... A weakening frontal system will continue to bring a band of snow across parts of the Kuskokwim Delta/Valley and Bristol Bay as it progresses eastward, with snowfall generally tapering off by tomorrow morning as the front disintegrates. Expect moderating temperatures behind the frontal system as well, with the entire area finally coming out of the deep freeze, with warming to at least single digits above 0F nearly everywhere by tomorrow afternoon. Attention immediately shifts to what will likely be the most significant winter storm system for the entire season thus far. An expansive and intense low moving across the far northern Bering will send a very potent attendant front and supporting 160 kt jet streak aloft directly across the whole forecast area late this weekend into early next week. A plethora of weather hazards will be possible as the front tracks across the Southwest from west to east, particularly from Saturday night to Monday morning. Strong southerly winds gusting as high as 55 mph will develop along the coastline Saturday evening, then spread inland over the Y-K Delta and Bristol Bay during the overnight. Moderate to heavy snowfall rates fueled by an influx of tropical moisture will follow in tandem with the winds, resulting in widespread areas of blowing snow that could produce near blizzard conditions near the peak of the event. The worst conditions are currently on track to peak earlier near the coast as the front arrives, or Sunday morning, with the worst of the wind/snow arriving later on Sunday into early Monday for further inland areas. On top of everything else, there is some chance the southerly and onshore winds will be strong enough to disrupt the newly formed ice pack, with potential for sea water to well up along/over shorefast ice. This could result in minor coastal flooding if enough water is able to make it through or past the existing sea ice near shore. The chance for this happening is highest where there are preexisting weaknesses in the ice, including near parts of Kuskokwim Bay. A Winter Storm Watch has been issued for the entire Southwest outlook area to cover the potential for all of the possible hazards mentioned above. Please see the product corresponding to your geographic area for further details on timing of impacts and expected snowfall amounts. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS/AKPEN (Days 1 through 3: Today through Monday morning)... A very powerful low and trailing frontal system will impact the entire forecast area during the course of the next two to three days. A North Pacific low will enter the far southwestern Bering this evening, then track northeast near the Kamchatka Peninsula as it rapidly deepens to near 950 mb by the time it approaches the Bering Strait on Sunday morning. To the south, the associated frontal system will bring a broad swath of gale to storm force winds that will affect nearly the entire Bering/Aleutians at one point or another, with impacts from wind and precip mainly in the form of heavy rain beginning earliest over the western Bering/Aleutians tomorrow morning. The strong winds and rain with the front will shift quickly eastward on Saturday across the southern Bering, easter Aleutians and Pribilofs, with storm force winds reaching the Southwest Coast and Alaska Peninsula by Sunday morning. The supporting low pressure center will stall in the northern Bering and support another area of westerly winds up to storm force, mainly over the northern and western Bering from Sunday to early Monday. && .MARINE (Days 3 through 5: Monday through Wednesday)... Gulf of Alaska: Flow becomes southerly and reaches gale force as a front enters the Western Gulf on Monday. Cyclonic development within the front near Prince William Sound shifts wind directions to west-northwest across the Gulf by Tuesday afternoon. Gales are likely initially through the Barren Island, becoming widespread across the Gulf throughout the rest of the day Tuesday. The GFS is hinting at a brief period of low end storm force winds through and east of the Barren Islands on Tuesday night. Bering Sea: A series of lows move in and out of the Bering through the early week. Two Russian lows skim the northern edge of the Bering Sea before drifting over Western Alaska, both of with look to produce widespread north-northwesterly gale force winds. The second low may bring a period of storm force winds to the northern Bering on Wednesday, per the GFS. A third, stronger, system out of the North Pacific enters the southern Bering on Wednesday night. The GFS solution is quite a bit more aggressive, but it is likely there will at least be areas of storm force winds Wednesday night into Thursday. && .LONG TERM FORECAST (Days 4 through 7/Tuesday through Friday)... Teleconnections support the amplified Rossby Wave pattern to continue across the North Pacific during the extended period. The Alaskan mainland will primarily remain under an upper trough which will allow for these cold temperatures to continue. Thursday appears to have the greatest chance of sunshine as the moderately positive Eastern Pacific Oscillation will weaken which supports a greater likelihood of upper level ridging to move over Southcentral. There is good ensemble agreement on this upper level ridge moving over Southcentral on Thursday, though it will be very short lived. Temperatures will remain cold as the upper ridging will help decrease cloud cover while the surface pressure set up will allow for a dry offshore flow pattern. This pattern can be conducive to nocturnal radiational cooling (clear skies and light winds) which allows for very cold temperatures overnight. With respect to snowfall, there is good deterministic agreement that a weak surface low pressure system will linger along the northern Gulf south of the Kenai Peninsula on Tuesday which will allow for snow showers to move from the northern Gulf into Prince William Sound. There is a high degree of uncertainty with respect to how much snow is expected. This surface low will then move southeastward and allow for cold air advection across Southcentral on Wednesday. Farther out west, there is the potential for a strong low pressure system to move across the Bering/Aleutians Wednesday through Friday. There is extremely low forecast confidence at this time due to poor agreement between deterministic and ensemble guidance. Both the GFS and GEM ensemble guidance show differences of 1.5 standard deviation or more between ensemble members which is a good indicator of a large variation of possible solutions. However, one common denominator expected with this low is a large area of gale force winds with the possibility of a smaller area of storm force winds within the aforementioned area of gale force winds. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...Winter Storm Watch 152 155 161. MARINE...Storm Warning 165 170 172-177 179 180 181 185 411-414. Gale Warning 155 171 178. Heavy Freezing Spray Warning 127 128 139. FIRE WEATHER...NONE. && SYNOPSIS AND MODEL DISCUSSION...KO SOUTHCENTRAL ALASKA...MF SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...AS MARINE/LONG TERM...KM/ED
4 winter weather, 3 winter storm, 3 heavy snow, 3 blizzard, 2 coastal flood, 2 high wind. Local standard time, as filed.
Bethel PD reported about 12 inches of snow. Hooper Bay PD reported 10-14 inches. Kipnuk PD reported only a little snow. Quinhagak PD reported 2-4 inches.
Reported observations of 19 inches at Eagle Song, 19 inches at Skwentna, 14 inches at Yentna, and 15.5 inches at Amber Lake.
Upper Tsaina SNOTEL 29.9 inches recorded.
Turnagain Pass SNOTEL recorded 14.1 inches. A spotter report from Lowell Point noted 8-11 inches of wet snow at 12/6/21 12PM. By 2PM, the road from Lowell Pt to Seward was closed due to an avalanche.
Kipnik PD reports flooding in airport overflow areas and one road covered in water.
PASL had a 24-hr QPF of 0.82 from 12/6 00Z to 12/7 00Z, or about 8 inches of snow using a 10:1 ratio.
Measurements: 1 inch of snow reported at office and 3 inches of snow reported in east Anchorage.
Report from NWS employee on 12/7: I left downtown about 3:50pm. Snowfall gradually increased with outright +SN at the Hiland exit on the Glenn Highway. Quite possibly approaching 8-12 of new snow in that area. Except for one section near the weigh station the snow was being blown in between the lanes and wasn't accumulating in the driving lanes. The snow rates decreased quickly in the first few miles up Hiland Road. It was clear this was a persistent feature as there was much less new snow in this area. Snowfall increased rapidly again past mile 5 of Hiland with moderate snow towards the end. So far I've had 8.5 new snow today with significant snow continuing as of 4:50 pm. 2.2 of new snow as of 8 am which was 12:1 ratio. The 6.3 was very low density fluff.
Lower Kachemak Creek SNOTEL recorded 17.6 inches and the McNeil Canyon SNOTEL recorded 9.2 inches. A trained spotter reported 13 of new snow overnight the 6th around 12 PM.
Blowing snow leading to half mile visibility at PALG and 3/4SM at several other neighboring airport ASOS.
PASN recorded: 30G36mph 1/4SM +SN FZFG VV006 at 12/8 10:20PM, while webcams showed whiteout conditions. PASN recorded 1/4 mile on numerous occasions as webcams showed whiteout conditions most of the night. PASN first went down to 1/2SM 36G58 mph SN on 12/8 at 2:47AM, diminishing to 1/4SM on 12/8 at 10:20PM.
Cold Bay recorded winds at 56G76 mph and Nelson Lagoon recorded west winds at 62G78 mph.
Nikolski recorded a peak wind at 52G105 mph on 12/9 at 2:02AM. The UNLA2 site in Unalaks recorded 79MPH 12/9 at 412AM. The Dutch Harbor APL crane recorded a 1s gust of 96 mph on 12/9/2021 at 2:07AM. The Dutch Harbor Pilot Station recorded 1s gust of 80 mph on 12/9/2021 at 2:12AM. Nikolski first reached warning criteria 12/8 at 5:42PM at 52G75mph.
Water over an Access Road near the harbor in Dillingham on Thu evening. (12/9)|Called Mitch (Port officer in Naknek) -- he said there were no known impacts, however in his 18 years of working there, he has never seen the water that high at the dock in Naknek...at high tide during the event, the water level rose to 1 foot below the dock. Mitch also mentioned precipitation went from SN to RA back to SN. He estimates he walked through about 2 ft drifts, but thinks actual snowfall was closer to 1 foot during this event. He also mentioned it was very windy.
Koliganek recorded winds of 39G52 mph and heavy snow with 1/4 sm visibility. Platinum and Cape Newenham airports reported frequent low visibilities of 1/2SM or less with winds to 35-53 mph in combination with moderate to heavy snow for a span of 12 hours. Similar conditions were recorded at Dillingham. Due to these conditions, power was knocked out, trees were toppled and phone service was cut off for about a week:https://www.kdlg.org/energy/2021-12-13/power-restored-to-nushagak-cooperatives-service-area-after-nearly-a-week-of-repairs.
Quinhagak and Kipnuk airports recorded visibilities of 1/2SM or less for a 3 hour period as winds gusted to 40 mph.
Exit Glacier SNOTEL recorded 14.0 inches. Received reports from spotter Karen Corrigan at 4PM on 12/9 of 9 inches and Dave (300 ft above Lowell Point) estimated 11 inches of snow between sunrise on 12/9 to 12/10 around 1 AM. At Moose Pass Railroad 9.6 inches were noted on 12/10 at 10:00AM.
Dennis Anderson (Homer, 12/9 7:15PM) estimated 6-8 in of wet/heavy snow with a foot in some places due to drifting & occasional whiteout conditions. Greg Arnold (Homer, 12/9 7:15PM) reported intermittent wet snow with an estimate of about 6 inches since the day before. Many reported deteriorated road conditions over Facebook along Cooper Landing.
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: 1007099, 1007179, 1007180, 1007181, 1007193, 1007194, 1007197, 1007198, 1007199, 1007200, 1007210, 1007230, 1007231, 1007232, 1007233, 1007234, 1007235.