I'm not sure but if you look at maps of both floods it seems that weather pattern in 1964 was a lot further north than the 1862 flood. Also, the wiki article for 1862 says that that was an El Nino year.
Calling out the atmospheric river implies a cause of purely precipitation, whereas the other floods are likely caused by some unfortunate combination of snowmelt runoff and high-precipitation events.
Comments
What separates the Christmas Flood of 1964[0] from these ARK storms? The wikipedia page discusses 1964 as an "atmospheric river".
[0] https://en.wikipedia.org/wiki/Christmas_flood_of_1964
I'm not sure but if you look at maps of both floods it seems that weather pattern in 1964 was a lot further north than the 1862 flood. Also, the wiki article for 1862 says that that was an El Nino year.
Calling out the atmospheric river implies a cause of purely precipitation, whereas the other floods are likely caused by some unfortunate combination of snowmelt runoff and high-precipitation events.