What exactly does "the lake effect" mean?

This was something I've been wondering ever since we knew we were moving to Erie. People always warned us about "the lake effect" and I would think to myself, "Listen, I grew up in Idaho, I know what a lot of snow is like. What is the big deal?"

Then tonight at about 8:00 Kinley looked outside on her way to bed and said "oh, the snow is coming back!!" It had just barely started coming down and she was already making sledding plans for tomorrow morning. Well, about 20 minutes later, just after I had turned their lights out, we noticed flashes of lightning and heard a bunch of thunder. "Odd," I thought. "That must be part of 'the lake effect' ".

By 9:00, the kids were asleep and I went down stairs to look out our back door. These first two pictures are what I saw.

Next, I realized that I was going to have to wear my Sorels just to take the garbage out (it gets picked up Sunday at midnight--weird.) So I put my boots on, went out to the garage, pushed the garage door opener and found this:

After about 10 minutes of shovelling, I had not even cleared enough of a path to get the garbage to the curb, so I went and recruited Abram.

If you saw pictures of our house earlier, you will remember that we have a walkway that slopes upward toward our house and then three steps up to the door. Now we don't:

So, I guess "the lake effect" means that over 16 inches of snow can accumulate in under 3 hours. The forecast calls for another 18 after midnight. You can guess what I am going to be doing tomorrow morning while Abram skis to school. Oh well! At least we got the first layer taken care of.