The topic of this post is not ice on the Kuskokwim River, but rather a severe and long-duration freezing rain event ("ice storm") yesterday in the lower Kuskokwim region. Bethel seems to have been hard-hit, with schools closed yesterday (I'm guessing this doesn't happen often). The following photo, provided on Twitter by Mark Springer of Bethel, illustrates the kind of difficulties residents ran into (click to enlarge).
The observations from Bethel airport recorded the remarkable persistence of rain at sub-freezing temperatures; rain began at 1am on Tuesday with a temperature of 21°F, and it continued uninterrupted until 4am today, by which time the temperature had risen to 31°F. The midnight-to-midnight precipitation total was 0.52", which was all rain.
Yesterday's 3pm surface analysis from Environment Canada shows the situation: a low pressure system to the south, strong high pressure (with associated cold surface air) draped over northern Alaska, and a frontal zone just to the south of Bethel.
Surface temperatures showed a sharp gradient between the Y-K delta and the Alaska Peninsula - see the red numbers in the 7am plot below.
Looking at the lowest levels of yesterday's 3pm Bethel sounding (below), the cold surface flow is from the northeast, but not far above the surface the flow has a southerly component, and a substantial above-freezing layer is evident from about 980mb up to 880mb. This is a freezing rain temperature profile: snow formed at higher levels melts as it falls through the warm layer, but then it is super-cooled below freezing in the short journey through the surface cold layer - and then it freezes on impact with any surface object.
Farther up the valley in McGrath, freezing rain developed around noon (at a temperature of 15°F!) and persisted for about 12 hours, although it was mixed with ice pellets or other solid precipitation at times owing to the deeper, colder surface layer. Additional light amounts have been occurring on and off today.
It would be worth taking a look at historical data from Bethel and McGrath to see how often freezing rain events of this magnitude have occurred in the past. Fairbanks has seen a considerable number of freezing rain events in recent years, but the phenomenon is by no means just a recent one in interior Alaska (see e.g. here https://ak-wx.blogspot.com/2018/01/freezing-rain.html). A comprehensive study of whether and where freezing rain is becoming more common, and whether it's an expected consequence of a warming climate in the far north, would be interesting and useful.
Update Nov 8: here's a paper about rain-on-snow events in Alaska, suggesting that frequency is likely to increase in (interestingly) southwestern and interior regions.
And here's another of my posts from some years ago: