Ares web alerts contain a time portion that can't be set in the UI
In the Ares Client, create a new system web alert for the next day. When you look at the record in the SystemAlerts table, you can see that the ActivateDate and InactiveDate fields contain the time component even though the UI in the Client only allows you to select a date, and the time component is set to the time of day the alert was created. So if you create an alert for the next day at noon, it won't show for users until noon the next day and the staff user doesn't have any control over this.
Released in Ares 4.6.6