How to force an alert during / after on a snoozed cell
The default behaviour is if an item is snoozed and the severity of that item changes if there is any action associated with a rule on that cell it will not fire.
This can be overruled within the action by setting Snoozing option under Restriction section to Always fire - as per screenshot below - this will mean that an action will fire if there is a severity change and the item is snoozed.
There is another way to generate an alert and that is to use the Ticker Event logger option. The behaviour is a little different from the first example - if there is a cell that is snoozed and the cell changes severity then this event will be added to the Event Ticker in the Active Console.
Note this option should be used with caution - as it is a system wide setting.