Tuesday, May 16, 2023

Severe Breakup Flooding

Unfortunately the worst-case scenario for ice jam flooding has occurred for some stretches of the Yukon and Kuskokwim rivers in recent days, as a "dynamic" breakup unfolds following the very cold April.

Flooding and damage has been particularly severe in Circle and Crooked Creek, located on those two rivers respectively.  Apparently the flood was equal to or worse than the record 1945 flood in Circle, and was worse than the benchmark 2011 flood in Crooked Creek.


As noted in this article, the risk of serious breakup problems was flagged ahead of time, with the combination of a cold April and deep snow pack being major contributing factors.  Rick Thoman highlighted historical examples of breakup flooding in his latest Substack post:


Courtesy of UAF's GINA group, here's a satellite-estimated view of severe flooding downstream of Circle on Sunday, after the breakup front moved downstream from the village.


Here are some NWS photos of the aftermath:


And Crooked Creek:

With very cold Aprils occurring with surprising frequency in recent decades, it seems that ice jam flooding will unfortunately remain a big problem for communities along Alaska's largest rivers for the foreseeable future.


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