Experts and BHG readers answer.
Snow Mold and Thatch Buildup
You've already done what should be done for snow mold: rake out the crusted mat as soon as you see it. For most home lawn situations, this is all that needs to be done. As temperatures warm and conditions dry out, the snow mold should disappear.
A small amount of thatch in the lawn is OK. If, however, the thatch layer is thicker than about 3/4 inch, it would be a good idea to dethatch your lawn. The best time to do so is early fall (mid-September in most of Zone 5). Early spring as soon as the soil has dried a bit is the second best time to dethatch a cool-season lawn such as bluegrass.