Weather radars operate on a handful of the same channels as access points do on the 5 Ghz band. It is required that, when a radar is active, all radios move to different channels. This alert is indicating that the configured channel for the access point heard a weather radar, and had to switch to a non-radar operating channel on 5 Ghz.
How to Troubleshoot
There is no need to troubleshoot this alert as it is purely informational. If it is causing client disconnections and frequent network issues, consider selecting 5 Ghz channels that are not used by weather radar.