I was not able to fit a mow in right before the grass went dormant this winter so it's really long (and sloppy looking) now. Weather is starting to warm up and the areas that had no grass (due some sprinkler issues) are starting to show new growth.

My question is: is it ok to go ahead and mow it now while it's still mostly dormant or will that harm the lawn in some way?

I would just be taking the top 'dead' layer off, not making it too short or anything.

If its ok, should i leave the clippings or the lawn or bag them? Do they provide any value if they're not green?