The result of the Wrangell landslide is seen on Nov. 20. (Alaska Department of Transportation and Public Facilities photo)

The result of the Wrangell landslide is seen on Nov. 20. (Alaska Department of Transportation and Public Facilities photo)

An Alaska climate expert reviews 2023’s weather and climate highlights

While Alaska didn’t have an ex-typhoon Merbok style widespread high impact event in 2023, there was still lots to contend with. Here’s a selection, in chronological order.

March: Northwest Alaska storminess

March was excessively stormy in Northwest Alaska and Kotzebue was especially hard hit. Back-to-back blizzards created massive drifts in town, blocking access to buildings and critical infrastructure as illustrated in the above photo, prompting the city and state to issue emergency disaster declarations and a “boil water” advisory. Winds at the Kotzebue Airport averaged over 35 mph on March 4 and 5 and peaked at 71 mph. Note that while functioning during the event, communications with the automated weather station were unreliable during the storm so at this time we can’t report, e.g., hours at blizzard conditions. The situation at Kotzebue was reminiscent of the repeated storms of March 2009.

May: Spring break-up flooding

Following a cold April over much of mainland Alaska, river ice break-up in the spring was quite a bit later than usual on the big rivers. Ice went out the Tanana River at Nenana on May 8 and 10 days later on the Kuskokwim River at Bethel, at both locations the latest break-up since 2013. With the cold April and deep snowpack in many areas, flooding problems were expected and indeed that came to pass in May. Catastrophic flooding occurred at Circle City on the Yukon River on May 13 and Crooked Creek on the Kuskokwim River on May 15 and moderate to severe flooding occurred at a number of other communities. On May 14 a state disaster declaration for the flooding was issued by Alaska Gov. Mike Dunleavy and then in August a federal disaster was declared to allow those impacted to access federal assistance. There was also significant flooding at Buckland and Kwethluk on the Kuskokwim, as well as on the middle Yukon River between Tanana and Galena May 17-19. Snowmelt flooding occurred in parts of the Glennallen area during most of the second half of May.

August: Mendenhall River glacier dam outburst flooding

Severe flooding occurred on the Mendenhall River near Juneau from Aug. 4 to 6 from a glacier-dammed lake outburst on the Mendenhall Glacier, which pushed the river to the highest level on record. There was severe riverbank erosion and several homes that had been more than 100 feet from the river’s edge were swept away as the land collapsed into the river. Many other homes were flooded by the rushing water. This kind of flooding is very much climate change-driven (summer 2023 weather had nothing to do with it), as the glacial lake has formed due to thinning of the Mendenhall glacier system and this type of flooding did not occur on the Mendenhall River until 2011. However, it is now an annual occurrence, though previously the flooding was not anywhere near this severe.

There’s also a short summary of this event in the Summer 2023 NOAA/ECCC Alaska and Northwest Canada Quarterly Climate Outlook.

July-August: Wildfire

You might be surprised to see wildfire here. After all, total wildfire area burned in Alaska in 2023 was “only” about 295,000 acres (119,000 hectares), which is less than half of the 1991-2020 median. Indeed, prior to July 24 there was an almost complete absence of wildfire. That changed with the lightning burst on July 24, with over 19,000 lightning strikes in Alaska alone, the most in any day since 2019. However, resulting wildfires were concentrated in the central Interior, with several fires close enough to populated areas for evacuation recommendations; these included the Clear/Anderson area between Healy and Nenana, and the Salcha River area southeast of Fairbanks. The Lost Horse Creek fire near the Haystack subdivision north of Fairbanks was declared a federal disaster area on Aug. 3, 2023. For Fairbanks proper, just over 150 hours with visibility reducing during 11 days in August was the most late summer smoke since 2005. The dramatic increase in the duration of wildfire smoke since 2000 is evident in the accompanying graph.

Fairbanks Airport hours per year with visibility reduced to six miles or less in smoke. All of these are due to wildfire smoke. Impressionistically, a visibility of six miles typically corresponds with air quality in the “unhealthy for sensitive groups” category.

Fairbanks Airport hours per year with visibility reduced to six miles or less in smoke. All of these are due to wildfire smoke. Impressionistically, a visibility of six miles typically corresponds with air quality in the “unhealthy for sensitive groups” category.

November: Wrangell area landslide

In the rugged terrain that makes up much of Southeast Alaska, landslides are not new. In August 2015, more than 40 landslides occurred on Baranof and Chichagof islands, including one on Harbor Mountain in Sitka that killed three people and produced extensive property damage. In December 2020, record short duration rainfall caused a landslide near Haines that killed two people and also caused extensive property damage. And now in 2023, on Nov. 20, a landslide at Mile 11 of the Zimovia Highway outside of Wrangell took the lives of six people.

In each case the details of the immediate causative factors are slightly different. Both Sitka and Haines events were triggered by extreme short duration (6- to 30-hour) rainfall. In the Wrangell case, the combination of a very wet autumn, heavy (but not record) storm scale rain and probably strong winds contributed to the landslide.

November-December snow

I wrote about the very heavy snow in Anchorage in November. However, the snowy pattern persisted over parts of Southcentral and northern Southeast Alaska through much of December. Here are some of the impacts from the heavy precipitation:

Seward Highway near the Sterling Highway Junction was closed for about eight hours Christmas Eve due to an avalanche, cutting off traffic between Anchorage and most of the Kenai Peninsula communities.

Haines Road Highway 3, the road connecting Haines Junction, Yukon, to Alaska was closed most of the week between Christmas and New Year’s on the Canadian side due to repeated heavy snowfall as well as blowing and drifting.

The Haines Highway rockslide near Mile 15 on Dec. 23 closed the highway and damaged at least one vehicle. This is an unstable area with a history of rockslides but this one was larger than many and was likely exacerbated by heavy precipitation and repeated freeze-thaw cycles this early winter. DOT had a slow time of clearing the roadway because of the threat of additional slides.

Richardson Highway during the week of Christmas was intermittently closed at Thompson Pass and in the Paxson area due to both avalanches and avalanche mitigation efforts by DOT.

• Rick Thoman is an Alaska climate specialist at the University of Alaska Fairbanks. He lives in Fairbanks. This article was originally published by the Alaska and Arctic Climate Newsletter.

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