A low tracked into Prince William Sound on Dec 12 as it rotated around a deep upper-level trough centered over Western Alaska. Snow spread west from the Copper Basin as the trough became northwest-southeast oriented.
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 low tracked into Prince William Sound on Dec 12 as it rotated around a deep upper-level trough centered over Western Alaska. Snow spread west from the Copper Basin as the trough became northwest-southeast oriented. Out west, the upper-level trough contributed to a strong push of cold air across the Bering Sea, which lead to blowing snow with widespread snow showers across the Alaska Peninsula.
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 12, 4:31 AM AKST, 4 hours 2 minutes earlier.
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 431 AM AKST Tue Dec 12 2023 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)... A high amplitude, longwave trough remains in place over western Alaska, extending south of Kodiak Island where it is anchored by a 510 dm upper-level low. Stout, southerly flow downstream of these features is drawing both copious amounts of moisture and a surface low north toward Prince William Sound this morning. The surface low is moving north-northwest along a stalled frontal boundary that is has been the focus for the heavy precipitation stretching from the central Gulf over the Central Chugach and Copper River Basin for the past 24 to 36 hours. To the west, conditions are quieter; however, residual moisture over Cook Inlet and a weak trough beginning to usher in colder air aloft has resulted in the redevelopment of scattered showers from Homer north to Anchorage. Snow levels did drop slightly overnight with rain changing to snow for Valdez, Cordova, and around the junction of the Edgerton and Richardson Highways in the southern Copper River Basin. Snow levels will likely remain steady through the day as the low tracks inland by mid morning and precipitation intensity during the afternoon and evening hours wanes. The exception to this is likely Cordova, where enough warmer air will work back in this morning to change snow, or mixed rain/snow, back to all rain for a time before colder air works back in later today. Farther west, the main challenge will not only be the extent of snow shower activity this morning across Cook Inlet, but whether the western edge of the precipitation shield makes it far enough over the Chugach to allow for some light snow for places like Anchorage and Palmer. The best chance for any light snow through the afternoon hours is over the Matanuska Valley. The parade of surface lows continues this evening as the next follows a similar track to the previous and moves toward Prince William Sound. Another round of heavy precipitation will move over the Central Chugach and across the Copper River Basin through Wednesday morning. Again, the biggest challenge will be the western extent of the precipitation. This system appears more likely to bring a round of steady, light snow to the Mat-Su Valleys, Anchorage Bowl and parts of the Kenai Peninsula Wednesday morning as the anchoring upper-level low to the west dips south and becomes more negatively tilted, drawing the surface feature and attendant shortwave back to the west. Snowfall amounts for these locations should be light, on the order of 1 to 3 inches. The southerly flow across the Gulf persists into Thursday with showers rotating around the lows. Much colder air will also advect in, bringing snow levels down to sea level across the Southcentral coast by Wednesday afternoon. TM && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Tonight through Thursday)... Conditions across the Bering Sea and Southwest Alaska remain largely driven by a large low pressure system in the Gulf of Alaska and a ridge set-up in the Western Bering Sea. The influence from these two systems is driving the strong influx of cold air from the northern Arctic down into the the Southwest coastline, Alaska Peninsula, and eastern Aleutians. This strong plunge of cold air will continue to produce gusty winds in the Eastern Bering, and across the the Alaska Peninsula through Wednesday. Storm-force gusts through gaps and passes along the Alaska Peninsula and Eastern Aleutians are expected during this time. Areas of blowing snow reducing visibility will be likely along the coastline from Bethel to Cold Bay. Similarly, this area will likely see new snowfall from persistent snow showers with the strong northerly winds diminishing only by Wednesday evening. The easing wind flow will weaken the presence of blowing snow across the aforementioned areas, however not out of the realm of possibility until about Thursday afternoon. The system that will eventually break the hold of this cold air flow will be a new low pressure system pushing in from the western Bering sea. This low pressure system will be initially noted by a leading frontal passage that will bring warmer southerly air arriving to the western-most Aleutians by Wednesday morning. The front will bring with it another round of precipitation, however this will likely come in the form of liquid rain due to the warmer temperatures. The front will be producing Gale-force southerly winds with some Storm-force winds possible further north into the Central Bering sea, however will likely be less "gusty" in nature due to the temperature of the air coming in being warmer than whats currently in place. The front will advance steadily eastward, reaching Unalaska by Thursday morning. As the front approaches, precipitation may initially begin as snowfall, but is expected to transition within a few hours to plain rain. By this time, the tight pressure gradient driving strong winds through the Eastern Aleutians will have relaxed, and the strong winds eased significantly. By Thursday morning, the parental low pressure center will enter the Western Bering sea, re-initializing the precipitation over the western- most Aleutians, however this time likely in the form of snowfall due to more colder air entrained in the system. CL && .LONG TERM FORECAST (Days 4 through 7)...Friday through Monday... The long-term forecast continues to feature general agreement on the continuation of the active pattern Friday through at least Monday. For Friday, a new deep upper trough drops into the western/central Bering Sea while a shortwave ridge moves over the eastern Bering and Southwest Alaska. The upper low that provided Southcentral Alaska with very active weather in the short-term continues to move eastward towards Southeast Alaska as the shortwave ridge builds over Southcentral. However, any break in weather associated with the ridge will not last long. Later on Friday and into Saturday, the deep trough in the Bering moves eastward and puts all of mainland Southern Alaska back in moist southerly to southwesterly flow. A front over then central and eastern Bering moves to the coast of Southwest later in the day on Friday and eventually to Southcentral on Saturday. There is lots of uncertainty exactly where a secondary low will spin up along the front in the Gulf on Saturday. All ensemble and deterministic guidance all show different solutions. However, generally speaking, coastal Southcentral chances for moderate to heavy precipitation are average. Southwest flow in the middle to upper levels continues for Monday as additional shortwaves lift northward through the Gulf and into Southcentral. The Bering Sea and Aleutians stay active Saturday through Monday as shortwaves pivot around the main trough. An additional low coming from Kamchatka looks to send its gale-force front from the western Aleutians Sunday afternoon to the central Aleutians by Monday morning. This will spread gusty winds and precipitation across the Aleutian Chain early next week. && .AVIATION... PANC...Expect scattered snow showers to continue through mid to late Tuesday morning. These snow showers could cause temporary reductions to ceilings and vis, especially between 12z and 15z. MVFR conditions are most likely in snow showers, but conditions could briefly drop as low as IFR. Conditions will improve during the morning hours on Tuesday, with dry conditions and VFR ceilings likely until snow with the next storm arrives sometime late Tuesday night or early Wednesday morning. Expect northerly winds to continue throughout the day, with the strongest winds, around 10 kt, through 18z. &&
SPECIAL WEATHER STATEMENT National Weather Service ANCHORAGE AK 447 AM AKST Tue Dec 12 2023 AKZ155-130300- Kuskokwim Delta- Including the cities of Bethel and Nunivak Island 447 AM AKST Tue Dec 12 2023 ...BLOWING AND DRIFTING SNOW ALONG THE KUSKOKWIM DELTA COAST THROUGH WEDNESDAY... Gusty northerly winds will persist across the Kuskokwim Delta through Wednesday. Wind gusts as high as 45 mph are forecast to continue along the Kuskokwim Delta coast and for Nunivak Island. No new snowfall is anticipated from Bethel west to the Kuskokwim Delta coast, though strong winds will continue to loft transportable snow already on the ground. As a result, visibility will be reduced at times, though will generally remain above one mile. Winds diminish on Wednesday, ending the threat of blowing and drifting snow. AKZ181-130300- Alaska Peninsula- Including the cities of Cold Bay and Sand Point 447 AM AKST Tue Dec 12 2023 ...BLOWING SNOW ALONG THE ALASKA PENINSULA THROUGH WEDNESDAY... Northerly winds gusting to 45 mph are currently combining with persistent snow showers to reduce visibility to one quarter mile at times. This evening, snow showers should decrease in intensity, allowing visibility to improve somewhat. However, intermittent reductions in visibility to one half mile will remain possible. Wind gusts are forecast to increase up to 65 mph Tuesday night, which may lead to prolonged periods of low visibility. Winds diminish on Wednesday, ending the threat of low visibility due to blowing snow.
Preliminary Local Storm Report
National Weather Service Anchorage AK
757 AM AKST Tue Dec 12 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0625 AM Snow Butte 61.53N 149.01W
12/12/2023 M2.7 inch Matanuska-Susitna AK Trained Spotter
A trained spotter measured 2.7 inches of
snow.
0712 AM Snow null 62.72N 143.89W
12/12/2023 M5.0 inch Copper River AK Trained Spotter
A trained spotter measured 5 inches of snow.
&&Preliminary Local Storm Report
National Weather Service Anchorage AK
802 AM AKST Tue Dec 12 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0712 AM Snow Slana 62.72N 143.89W
12/12/2023 M5.0 inch Copper River AK Trained Spotter
Corrects previous snow report from null. A
trained spotter measured 5 inches of snow.
&&4 winter weather, 1 blizzard. Local standard time, as filed.
Whittier MAWS reported visibility one half mile or lower with winds gusting in excess of 31 knots (36 mph) on the morning of December 12 through shortly after noon. Similar visibilities were observed at Portage Glacier during the same time period.
NWS employee measured 6 of snow located 3 miles east of office over a 9 hour period. Storm totals: 9.9 Strawberry and Northwood, 9-11 inches in southeast Anchorage. 11-14 inches on the Anchorage upper hillside. 8.8 inches in Eagle River. Information from LSRs.
The observation at PATO: 8:53am W 7G25 and ended at 12:53pm.
The Cold Bay ASOS reported visibility one half mile or less with winds gusting as high as 45 knots (52 mph) during a period of snow showers during the afternoon of December 12. Blizzard-like conditions were observed at times in Cold Bay and King Cove.
Convective snow showers induced by cold air passing over the relatively warm sea surface temperatures of the Bering Sea led to a five hour period of blizzard conditions recorded at the Port Heiden AWOS on December 13, during which winds gusted as high as 37 knots (43 mph). This was preceded by intermittent periods of blizzard-like conditions on December 12 and into the morning of December 13, caused by the showery nature of the snowfall. Observations to the north and south along the Alaska Peninsula did not show visibility drop below 3/4 mile.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Alaska in 2023Every state in 2023This day in weather historyWarnings in Alaska, December 2023
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: 1153638, 1151734, 1151736, 1153640, 1153681.