When you cut the top low, the drop in photosynthesis in the plant will reduce the sugars sent to the roots and basically self prune the roots. I leave mine long all year.

I guess there is some difference to take into consideration if you might get snow. Maybe someone else will help.

I get snow and I'd still follow DChall's advice. A well-fed, well-cared for lawn doesn't have too much trouble with snow mold. I've never seen any on my lawn. I cut to 3 1/4" winter and summer, my color maintains until temperatures drop under twenty consistently, and greenup is nice and early.

Even with those that do, it's rarely that destructive unless the grass is very weak. My neighbor is an example of this as he loses large patches every year to it. He also never feeds, cuts when it reaches four to five inches and then scalps it, and never waters.

Or, in other words, I'm not surprised.

If snow mold is a worry, ordinary corn meal or cracked corn applied about now seems to prevent it (according to my Canadian friends).

I mow shorter in the fall because my lawn mower mulches leaves better at the lower setting. By the time I am done mulching leaves, the grass is dormant for winter... so photosynthesis isn't really a concern.

If I didn't have 12 mature oak trees in my yard and leaf mulching was not a continuing process for three months, I probably would mow at the same height all year.

I was mulch mowing leafs in the snow last week. ;-)