The forest fire near Chernobyl that broke out a week ago has spread radionuclides, notably plutonium, over eastern Europe, Asia, Alaska, and is now moving in over the west coast of the US.
This image from the downloaded Windows HYSPLIT atmospheric dispersion model shows the spread of this plume, as of 2 PM Eastern time on May 7.
This simulation uses actual winds, not predicted winds.
It has moved over southern Alaska, where it is currently raining, and northern B.C. Some tendrils have moved over NW Washington, Salinas CA, Fresno CA, Santa Barbara CA, and Las Vegas NV.
For users of Google Earth or other visualization software, a KML file is available here.
As of Friday morning, the rain outside of Fresno has some measure of this smoke plume mixed in with it, and is falling as snow in the mountains to the northeast.
The plume should become entrained in a storm that is developing in this area. This image is a forecast for Saturday night. A snowstorm is moving over the Rockies, and the rain and snow will later move over the northern plains, the upper Great Lakes, into Canada.