Kotzebue has been seeing some rough weather lately, with the second big blizzard of the past two weeks winding down today. Twitter user Tundrabilly has been documenting the conditions.
3-4-23, noonish, Kotzebue, Alaska, -9 d Fah (-23 C), wind chill -41 d Fah (-41 C), wind speed E 38 mph (61.16 km/h, gusting to 48 mph (77.25 km/h). Didn't see anyone out . Winter's here perty hard. pic.twitter.com/kTburqpgNm
— Tundrabilly ❄☃️🇺🇸 (@tammaq13) March 4, 2023
Here's a chart showing the frequency of blizzard conditions as a percent of all hourly ASOS observations in the last 25 years. February is peak blizzard season, and the climatological frequency doesn't drop off a whole lot in March. However, the percentage only peaks at about 1%, so a true blizzard is unusual weather even at this time of year.
The much lower frequency in January might be at least partly a statistical artifact, but it appears in both the first and second half of this 25-year period, so I'm inclined to think it is a real feature of the climate. Presumably the jet stream drops far enough south in January that strong storms are less common in Kotzebue; but this is a topic for further investigation.
If we exclude the visibility requirement of the blizzard definition, then the December and November frequencies jump up above the February and March frequencies, respectively. It seems that low visibility is more readily attainable in late winter, perhaps because there's much more snow lying on the ground throughout the region (available to be blown around), or perhaps because the air tends to be drier in late winter (making snow more powdery).
That was quite a blizzard, 40-some continuous hours of by-the-book blizzard conditions (it seems some obs were missing toward the end and the anemometer may have been iced up or something, so hard to get an exact # hours). That's really something since the criteria is so hard to meet even in Alaska. By the way, on March 1st Juneau had 3 or so hours of blizzard conditions at the airport (possibly worse downtown?) NWS put out a rare blizzard warning for Juneau.
ReplyDeleteLooks like this winter is the first since 2004-05 that Kotzebue had blizzard conditions in every month from November through March. Impressive indeed.
DeleteI hadn't seen those obs from Juneau. 45+ knot wind gusts! But at/above freezing at the height of it - that's a warm blizzard.
https://www.ktoo.org/2023/03/08/kotzebue-declares-disaster-amid-back-to-back-blizzards-and-water-system-failures/
DeleteThanks for the link. Remarkable.
DeleteWarm blizzard... new term? It seems very often in Alaska, blizzard-like conditions coincide with warming, with a low moving in from the west or south and bringing in warmer air and/or stirring up the cold surface air, unlike places down south where a NW cold surge is responsible.
ReplyDeleteYes, good point; the classic Great Plains blizzard occurs with cold NW winds, but that's not typical everywhere.
DeleteI believe there used to be a temperature criterion in the NWS blizzard definition (20F???), but I can't find any documentation of it. I imagine that the fine, penetrating character of the driving snow in a classic blizzard is only found at low temperatures - a "cold blizzard" if you will.
If you've never been there have a look at most coastal communities on Google Earth or whatever....miles of water, ice, or tundra then BOOM dwellings and personal items stored outdoors. None or few natural weather breaks like trees or hills to arrest or deflect the prevailing winds.
ReplyDeleteIn old times they dug into the ground then covered an upper rounded portion of the dwellings with local materials. Crawled in through the roof or via a cold air trap tunnel. A fire hole and that entry was built into the roof. Now everything is square and fights the wind, with only the space between buildings for the snow to go.
Powerlines are above ground, and water and sewer, if available, is often disabled. It's a rough place requiring tough folks to survive.