What you could do is use a time based interval for time being.

You could use signal throw and catch events to notify users based on that status field.

Let's say HIGH is 1 hour, medium is 2 hours and low is 3 hours.

Then you could use that field value to trigger a signal throw event and email the user based on your status field.

Although you need to train them to know why they are receiving what.

This is doable with Forms 11 Update 3.

You can use timer event and exclusive gateway to achieve it. The  conditional expression for gateway is such as "/dataset/_task_priority[@_step_id=3]="High"" , 3 is the step id of the user task.