The Cluster Failover alert indicates a change in the active node. This alert remains active for the amount of time specified in the alert's advanced settings.
To edit these settings, right-click the server in the Servers tree and select Configure Alerts. Click the Advanced button on the Cluster Failover Alert and edit the time.
Prevent cluster failover alerts when you have a scheduled failover
You can temporarily put the server into maintenance mode by right-clicking the server in the Servers tree and selecting Maintenance mode. When the scheduled failover is over, right-click the instance in the Servers tree and select Disable Maintenance Mode.