Tuesday, July 8, 2025

More Heat and Lightning

[Update July 10]

Rick Thoman pointed out that a SNOTEL site near Kobuk reached 93°F on Saturday, a remarkable temperature for this typically (slightly) more maritime area in the northwestern interior.  (Note that SNOTEL thermometers are more reliable than the warm-biased RAWS instruments.)

But it was back down to 30°F yesterday morning - that's quite a change.  Click to enlarge:


[end of update]

The second big heat wave of the summer for central and northern Alaska came to an end with a tremendous amount of lightning in the past couple of days.  The ALDN recorded over 12,000 cloud-to-ground lightning strikes in the 24 hour period ending at 6am today, with several regions of strong activity:


Yesterday was the 5th day this summer with over 10,000 ground strikes recorded, and this is the most of any summer in the modern ALDN history since 2012 (note that this calculation includes northwestern Canada to the west of 129°W).  Previously the record was 4 such days in both 2016 and 2017; but some summers don't see a single day this active - for example, the peak lightning day last summer was 6500 strikes on June 23.

In terms of total year-to-date strikes, 2025 remains in second place behind 2015.


Many new fires will have been started by this latest round of lightning, but the weather is now much cooler and more humid, which will greatly aid fire control efforts.  There are two substantial fires between Fairbanks and Nenana, collectively called the Nenana Ridge Complex, with expansive evacuation orders in place.  These fires have been burning since around June 20.


Looking back at the heat wave, it peaked over the holiday weekend, and was focused over the northern and northwestern interior, as well as the Brooks Range.  After seeing its latest measurable snow on record (again) only 4 weeks earlier, Bettles reached 90°F on Saturday, and that's only the second 90°F this century at Bettles - the other was in 2019.  Bettles is now running in second place for number of 80°F and 85°F days this summer (15 and 8 respectively).  What a turn-around from the cold start to summer:


Up at Anaktuvuk Pass, the temperature reached or exceeded 80°F for 4 days in a row, which is quite extraordinary for the location (2100' elevation at 68°N).  Even a single 80°F day is very unusual up there, but the count has now reached 6 days this summer; the previous record from recent decades (since the mid-1980s) is just 2 such days in 2016.

2 comments:

  1. FYI: Kobuk reached 93°F on Saturday, a remarkable temperature for this typically more maritime area in the northwestern interior.
    From Google: Kobuk, Alaska is not considered maritime.
    Kobuk is located on the Kobuk River in Northwest Alaska, near the Brooks Range. While the Kobuk River eventually flows to the Chukchi Sea (part of the Arctic Ocean), Kobuk itself is significantly inland and not directly on the coast.
    I did some survey work at Dahl Creek (near Kobuk) one summer, it was hot there!

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    Replies
    1. Fair enough, it's not maritime - but arguably "more maritime" in the sense that any western interior location is more often exposed to maritime air rather than Canadian/continental air.

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