Alerts aren't terribly "smart"...
The time dimension is really only available based on the Time Granularity:
So if you are looking at Previous Day, you would use Daily... I believe the alerts will fire a little bit after Midnight when the days data has finished processing.
As for a "per Campaign" type alert, sadly, I think this would require creating an alert for each campaign. Use a segment to pull out data for "campaign x" and "campaign y", etc, then you would just put the campaign name in the Title to identify it....
There is really no way to have a single alert drive an email for each campaign by name....
As opposed to an alert, if you want some sort of all in one campaign report, you might consider making a Daily emailed report that shows you your campaigns, and you could use some segments and logic to identify campaigns that dropped to 0 and highlight them in an area of the report?