A North Pacific Low approaching the South Mainland of Alaska brought an early season heavy snow event to many areas of the Susitna Valley. While this area can be accustomed to heavy snowfall, and is popular for winter recreating, heavy snow in the first week of November was unusual.
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 Pacific Low approaching the South Mainland of Alaska brought an early season heavy snow event to many areas of the Susitna Valley. While this area can be accustomed to heavy snowfall, and is popular for winter recreating, heavy snow in the first week of November was unusual.
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 Nov 27, 5:46 AM AKST, 1 hour 49 minutes earlier.
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 546 AM AKST Fri Nov 27 2020 .ANALYSIS AND UPPER LEVELS... A large trough extends from eastern eastern Russia to the AKPEN with a ridge over the Alcan border. Multiple strong shortwaves extend from the eastern Bering to the central Gulf just north of the primary jet axis. Active weather is present over the western Bering, Aleutian Chain and Southcentral while Southwest is mostly calm with low stratus. Over the Gulf, a compact low can be seen on satellite moving north towards the Prince William Sound. The low level circulation has taken on a slight negative tilt with the low center expanding in area as well. Radar returns over the Middleton island show convective showers to the north of the low center. The Kenai radar shows a narrow deformation band extending from Kenai city to Skwentna. This band is the primary focus for the eastern domain forecast in whether or not it will remain over the western Kenai Peninsula or drift east over Anchorage. Out west two compact lows can be seen on satellite. The stronger of the two is currently over Nikolski and brought storm force winds to the south of Adak early this morning. Surface observations at Adak measured peak winds of 43 kts. This storm is about 50 miles south of where it was forecast, resulting in lower windsover the central Aleutians. The second storm to the north of Shemya has also been measuring storm force winds at buoy 70. && .MODEL DISCUSSION... Models changed drastically in the afternoon and evening runs in regards to the track of the Gulf low. The evening package models indicated a deformation band setting up from Anchorage north to Willow which aligned with both the GFS and NAM 00Z models runs. Overnight the deformation band has moved slightly to the west and now extends north south from Skwentna to Kenai City which aligns with the 06Z NAM and GFS solutions. This deformation band formed with system that moved over the Cook Inlet Thursday afternoon. It is difficult to discern whether or not the band has been influenced by the low in the Gulf at the time the forecast issuance, however at this time there is no indication that the band will move back to the east to bring heavy snow from Anchorage north to Willow. && .AVIATION... PANC...Based on current radar observations the band of heavy snow which had the potential to cause periods of heavy snow over the area, has set up west of the airport. It is currently expected the band will mostly remain west of the airport for the day. However, potential eastward jogs may temporarily deteriorate conditions. Thus, have significantly improved the conditions over the airport today from previous forecasts. There still remains significant uncertainty, so left a period of MVFR snow in for later this morning, when the band is most likely to make its closes approach. If trends continue keeping the band west of the airport, the morning TAF will need to be improved to VFR for the entirety of the day, with only occasional snow showers that make it over the mountains being the only threat for snow. Expect further adjustments through the morning as certainty improves. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2: Today through Saturday Night)... An incredibly complex and dynamic weather scenario is unfolding across Southcentral this morning. An area of low pressure moved up Cook Inlet yesterday evening, with a Gulf low now having taken over as the main low. The importance of the first low was to set up a deformation band of snow over the Kenai Peninsula, extending into the western Susitna Valley. A number of the evening model runs indicated the band of snow would move east into Anchorage, the western Matanuska Valley, and along the Parks Highway. This has not happened. Instead, the band of snow remains parked in much the same area as it formed. The second Gulf low at this point is certainly feeding moisture into the snow band, but has not moved it much. If anything, the band has been slowly crawling westward with time. The latest NAM run shows the band perhaps drifting a back to the east a bit later this morning into the interior Kenai Peninsula, but keep all of the Anchorage Bowl and the Matanuska Valley dry. Any potential snow could occur if the influx of Gulf moisture widens the band such that south and west Anchorage may briefly get a bit of snow. Otherwise, any snow showers will be the stronger survivors of the downsloping largely keeping Anchorage and the Mat Valley dry today. Thus, have cancelled the Winter Weather Advisories for Anchorage and the Mat Valley. Meanwhile, for the Kenai Peninsula and the Susitna Valley, the steady snow associated with the band could result in large snowfall totals for areas that stay in the band longest, assuming it doesn't move all that much. Winter Weather Advisories are in effect for these zones, but would not be surprised if localized totals above a foot are realized, especially in the western Susitna Valley near Skwentna, which has the benefit of upslope enhancing the snowfall rates. Steady snow will continue all day through the Kenai Mountains, with Turnagain Pass potentially approaching 2 feet of new snow by the time the steadiest precipitation is over. For lower elevation locations, just enough warm air is allowing rain to mix in with the snow in Whittier and Portage. Seward may mix with rain at times as well today. Hazardous driving conditions from steady snow are expected all along the Seward Highway from Turnagain Pass south and along the Sterling Highway from Kenai-Soldotna east. The Gulf low will lift into Prince William Sound and the coastal mountains this afternoon and dissipate. This will also cause the inland snow band to rapidly fall apart and dissipate. The break in the weather will be very short, if there's one at all along the coast. A front associated with a strong low will move into Kodiak Island late this afternoon into this evening, then rapidly shift northward to the north Gulf Coast tonight. Winds with the barrier jet will increase into storm force late tonight into Saturday morning as the front approaches. The front will keep steady snow ongoing along the coastal mountains through the day on Saturday. The front itself will dissipate during the day, but the onshore flow behind the low will keep upslope precipitation ongoing. There remains some uncertainty, but the parent low center currently is expected to move into Prince William Sound late Saturday night into Sunday morning. Thus, expect the mountain snow along the coast to continue more-or-less steadily through Sunday morning. Some of that moisture could make it inland, especially into the southern Copper River Basin Saturday night, but with the incredible spread in the models with the present system, it can't be ruled out that the Cook Inlet region has at least some chance of snow with that track as well. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)... A fairly benign but cold weather pattern is instore for Southwest Alaska over the next 3 days. A storm system is moving east- northeastward across the eastern Aleutians and along the AKPEN, placing the Kuskokwim Delta and Bristol Bay to the northwest of the low center. This will promote strong cold air advection as east- northeasterly winds will bring in continental polar air from the Alaskan interior to the area. Observations and radar show snow falling across Bristol Bay as the outer snowbands are currently moving across that area. Precipitation type is not an issue for this system as temperatures will remain cold enough to support snow for the entirety of the event. The next 2 days will be fairly dry with a cooling temperature trend as brisk northeasterly offshore flow continues. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)... A storm system is currently moving east-northeastward along the central and eastern Aleutians today. Widespread storm force winds are expected across the area. The High Wind Warning was cancelled for the central Aleutians as observations and ASCAT data showed winds below warning level criteria during the peak of the event. Winds will gradually decrease across the central Aleutians today in the wake of this storm system. A second area of low pressure in the western Bering will gradually weaken today, though it will produce gale force winds in the western Bering/Aleutians. A third low pressure system will move into the western Aleutians Saturday evening and continue eastward through Monday afternoon. There is confidence the center of this low will remain well to the south, however the northern edge of this system will bring widespread gale force winds and areas of storm force winds Saturday night through Monday afternoon. The largest seas expected with this storm will be on the Pacific side of the Aleutians and will reach 20-30ft Monday morning through Tuesday morning. These seas will remain long in period. && .MARINE (Days 3 through 5/Sunday through Tuesday)... Gulf: The active pattern continues with high winds and waves following back to back storms into the Gulf. A gale force low will move into the Gulf Saturday afternoon, expected to dissipate throughout the day on Sunday. Monday morning, a front associated with a low south of the Chain will enter the western Gulf. This system could bring storm force winds as it propagates towards the northern Gulf Coast with a barrier jet looking to set up Monday evening. After this, strong southerly flow will overtake the Gulf Tuesday morning, expected to dissipate throughout the day. Bering: A large and strong area of low pressure looks to skirt the Chain beginning on Sunday morning bringing with it the potential for storm force winds and waves. Expect high winds and waves into the central Bering between Sunday morning and Tuesday afternoon. Tuesday evening, most of the high winds and waves look to remain confined to the eastern Aleutians and Bering which should begin to dissipate through Wednesday. After this, there looks to be a short break in the active pattern through Thursday with calm winds and seas. && .LONG TERM FORECAST (Days 4 through 7/Monday through Thursday)... The active weather pattern continues throughout the long term. Precipitation will continue for the northern Gulf Coast with snow for the higher elevations on Monday, as an area of low pressure continues to weaken as it moves further inland. Temperatures look to remain warm with this feature, with rain expected for the lower elevations and snow for the highest elevations. Right behind this is a front associated with a low in the North Pacific, bringing another round of precipitation to Kodiak Island and then to the coastal areas Monday afternoon, along with an increase in winds. Expect precipitation to make its way inland Monday evening with this front. Temperatures aloft look to remain relatively warm, with rainfall looking to be the dominant precipitation type with this system. We look to dry out a bit after this, with precipitation mostly remaining across the coastal locations and higher elevations Wednesday. This looks to continue through Thursday, with an increase in precipitation expected, as another low is anticipated to move from the southern Gulf into Prince William Sound. This could switch rain, from the previous low, to snow as warm air is replaced by cold air. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...Hurricane Force Wind Warning 174. Storm Warning 119 155 172 173 175 176 177 411. Gale Warning 120 125 130 131 138 139 150 160 165 170 171 178 180 351 352 413 414. Heavy Freezing Spray Warning 180 181. FIRE WEATHER...NONE. && SYNOPSIS AND MODEL DISCUSSION...CJ SOUTHCENTRAL ALASKA...JW SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ED MARINE/LONG TERM...KM/CK
2 heavy snow. Local standard time, as filed.
Eagle Song Lodge, located 25 mi SW of Willow, AK, reported 18 inches of snow in 12 hours. This brought their seasonal snow total up to 62 inches before the end of November. Further to the north near Yentna, AK, there were anecdotal reports of over 2 feet of snowfall.
Alaska DOT reported 4 to 6 inches of snowfall at Chulitna, AK. Further south at the Eagle Song Lodge, 25 mi SW of Willow, AK, a trained spotter reported 10 inches of new snow with snowfall rates exceeding 1 inch per hour.
These snowfall reports occurred in November and December, as snowfall began on November 30, and continued in most areas until the afternoon of December 1st.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Alaska in 2020Every state in 2020This day in weather historyWarnings in Alaska, November 2020
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: 930547, 930548.