Yesterday I saw that a lot of sensors around the Kyoto area, especially along the north/west coast, were getting elevated radiation levels. I looked at the history graphs, and it looks like that whole area gets a big spike about every 4-5 days. Does anybody know why? Could it be related to the proximity to North Korea?

Next time it happens, compare the higher RADCON levels/stations with this Japan radar map and you will likely find that as the storm moves across Japan the radiation will rise. While this is real radiation and a concern, as long as it does match the radar... we should be able to rule out some new Fukushima style event.

http://www.jma.go.jp/en/radnowc/

Aha, that makes sense! Thanks. I imagine then, the same may be true for the USA if I see a similar pattern.

Correct, that is what I do for the USA map.