Alaska's Wild Winter Solstice Week
It’s been a very eventful December weather and climate wise across Alaska and northwest Canada. This post highlights some of the many happenings since the change in the weather pattern mid-month that brought an end to the record snow in southcentral Alaska and relatively mild temperature for most of mainland Alaska.
Periodic reminder: for this kind of weather and climate information in closer to real time feel free to follow me at https://mastodon.social/@AlaskaWx
Notable cold
Much of central and eastern Alaska has had quite low temperatures since mid-month. However, at climate stations with 40 or more years of observations there have been hardly any daily record low temperatures set. However, in many places this was still the coldest December weather in more than a decade, and the duration of the deep cold was significant in the eastern Interior. Fig. 1 plots the lowest temperatures reported from various weather and climate stations. Chicken, Alaska at -62F (-52.2C) and Pelly Crossing and Mayo, YT at -61F (-51.7C) were the lowest reliable reports. As always, slightly lower temperatures are sure to have occurred in other valley bottom locations.
Chicken: The NWS cooperative observer at Chicken reported five days in a row with highs in the 50s below and lows in 60s below, including a low of -62F (-52.2C), which will be the lowest reliable temperature in Alaska for 2022. This is the longest duration of temperatures this low since January 2009. Chicken has daily climate observations (with a few gaps) since the winter of 1996-97.
Eagle: A couple of pulses of downriver winds at Eagle busted the temperature inversion, so multi-day temperature averages are not especially unusual. However, the NWS cooperative observer on the morning December 24th reported a high temperature of -51F (-46.1C) and a low of -56F (-48.9C). That’s the lowest December high temperature since 1980 and the lowest December low temperature since 1995.
Tok: The commercial hub of the upper Tanana Valley, with an average temperature of -47.5F (-44.1C) December 19-23 and a low of -54F (-47.8C) made this was the coldest 5-day period since early December 2012. However, slightly lower daily temperatures were recorded in January 2022 and 2020 and in December 2013.
Anchorage: The Anchorage International Airport’s low temperature of -12F (-24.4C) on December 19 was the lowest temperature since January 2017. At Merrill Field the low temperature of -17F (-27.2C) was the lowest December temperature since 2012.
Kenai Airport: on December 20 the low temperature of -31F (-35C) was the lowest temperature since January 18, 2017. This is also the lowest temperature in December since 2001. The high temperature on the same date of -16F (-26.7C) is the lowest daily high temperature in December since 1970 and the lowest any date since the great January 1989 cold snap. Kenai airport had easily the lowest reported temperatures on the northwest Kenai Peninsula for this event, e.g. at Soldotna airport the lowest temperature in this cold snap was -23F (-30.6C) on the 20th.
Ketchikan: Most notably, the high temperature at the Ketchikan airport on December 19th and 20th of 17F (-8.3C) are the lowest December high temperatures since 1984. Daily record low temperatures were also set on December 19th (+5F, -15.0C) and 21st (+3F, -16.1C) and tied on December 20 (+8F, -13.3C).
Strong Winds
December 21 to December 23, 2022 brought extremely strong winds to portions of Alaska. On December 21st into the early hours of December 22nd, a northward moving weather front brought Cold Bay (lower Alaska Peninsula) an extended period of strong winds, capped off with seven consecutive hours of sustained winds in excess of 70 mph, and peak wind speed of 88 mph. Cold Bay is a windy place, but even so there was building damage reported around town. On December 22nd the core of the strong winds moved northeastward, with wind gusts over 60 mph at the upper Alaska Peninsula communities of Pilot Point, Naknek and King Salmon.
On December 23rd the strong winds moved into southern mainland Alaska. At Anchorage Airport, the peak wind speed of 68 mph is the highest since a 71 mph gusts on around midnight March 12-13, 2003. [This stat has been updated thanks to a reader who pointed me to the March 2003 event that produced wind gusts in excess of 100 mph in parts of Anchorage and produced widespread damage—RT Dec 25, 2022].
In the Mat-Su area, Palmer Airport peak wind 82 mph and Wasilla Airport reported a peak wind of 72 mph before the power went out early Friday afternoon. In the Palmer and Wasilla areas, while peak winds were similar to the early January 2022 windstorm, the strong winds this time around did not last as long and there appears to have been much less property damage. However, with plenty of snow on the ground, in many areas there was very poor visibility in blowing and drifting snow (which is exacerbated by headlights when driving) and conditions were poor enough that Alaska DOT and Mat-Su Borough strongly discouraged travel during the afternoon and evening hours. At Anchorage Airport, the peak wind speed of 68 mph is the highest since a 75 mph gust on March 3, 1989. In the Mat-Su area, Palmer Airport peak wind 82 mph and Wasilla Airport reported a peak wind of 72 mph before the power went out early Friday afternoon. As is often the case with strong winds in complex terrain, at the same time as downtown Anchorage was being buffeted by the winds, some frequently windy hillside neighborhoods had hardly any wind.
Power problems were reported in southwest Alaska on December 23rd, with peaks winds of 71 mph at Toksook Bay and 63 mph at Bethel. The FAA automated weather station at Hooper Bay has been offline since ex-Merbok hit in September, but sone building damage was reported.
The same weather feature aloft that sparked the strong winds in southcentral Alaska also had an impact on weather on the north side of the Alaska Range. Wind were not nearly as strong, but were enough to briefly break-up the (typical for mid-winter) strong surface temperature inversion and mix milder air right down to the ground. At McGrath, the temperature jumped from -30F (-34.4C) at 5am AKST to +15F (-9.4C) at 6am. This 45F (25C) increase is the largest one hour temperature change on record at McGrath (since 1948). Just between 530am and 545am the temperature rose 30F (16.7C). At Fairbanks Airport the increase wasn’t quite as dramatic because temperatures just above the ground were not as mild as at McGrath, but nonetheless the change from -28F (-33.3C) at 6am to -1F (-18.3C) at 7am is the second largest one-hour increase on record (since 1948).
The same basic weather pattern that brought cold to eastern Alaska and the Yukon also supported persistently warmer than normal conditions to much of far western and southwest Alaska.
Flooding Rains
Persistent southeast winds aloft brought repeated pulses of high moisture content air into the eastern Aleutian Islands, resulting in flooding rains at Unalaska. While there are significant gaps in the Unalaska daily precipitation observation record, the 5.18 inches (131.6 mm) of rain that fell December 20-22 appears the 3-day largest winter (December-February) precipitation total since January 1991. KUCB radio’s reporting on the impacts at Unalaska is here.
Lack of Sea Ice in the Northern Bering Sea
In the northern Bering Sea, repeated storminess in November and early December kept sea ice growth slow, and in early December total ice extent in the Bering Sea was near the lowest on record. The regional climate impacts of the lack of ice can be readily seen in Fig. 2, which plots the daily temperature departure from normal since October 1 at Nome (top) and Savoonga on St. Lawrence Island (bottom). Sea ice historically reached St. Lawrence Island sometime in November, and once there’s sea ice temperatures can get much colder since winds blowing from the north are coming off of ice and not open ocean water (which can not be colder than about 29°F). However, this year the ice has just reached the eastern shores of St. Lawrence Island as of December 24th, and this is reflected in the fact that Savoonga has not had a single day cooler than normal since before Thanksgiving. In contrast, Nome, on the southern Seward Peninsula coast and having a less (not none) sea ice effected climate, has had a couple spells of cooler than normal weather since late November.
The weather pattern change mid-month brought somewhat cooler temperature and turned winds around to a northeast to east direction to the northern Bering Sea region. This served to spread out what sea ice there was near the Alaska coast and push it westward, but in some areas where the wind was blowing from the land to the ocean, what thin ice was there was blown out to sea. The result of this at Nome is seen in Fig. 3, a stunning photograph by J. Oquilluk, who captured a beautiful winter solstice sunrise over the Bering Sea from the beach at Nome, looking southeast across completely ice free waters where just the day before there had been thin sea ice.
