Between July and September we always do morning EMH due to the afternoon storms. By the time the rain and thunder roll in, we are back at our resort for a mid day break. As a pp mentioned, these storms do take time out if your day. Not all storms are brief, passing showers; some storms can be intense, and last for some time.
Just have to comment upon reading those posts indicating they were not scanning guests during morning EMH at MK, thereby allowing everyone into the park at the same time. Not really sure what to think about this considering EMH is an onsite perk. I hope this is a temporary thing; if it isn't, I would imagine there will be a boatload of complaints.