Alert on group

I'd like the ability to alert off of a group's status. You are able to set "Monitor count threshold to decide the monitor group's status" but you can't then alert off of this.

Our use case is that we group monitors by datacenter or zone and we'd like to create an escalated incident (via pagerduty) when the group hits a specific threshold. This allows us to page an "all hands on deck" type scenario.