Check out this composite radar image from the National Weather Service, 20:18 UTC, February 10, 2008:
This is great imagery of lake effect snow bands. For folks who live to the immediate east of any of the Great Lakes, this is a well-known effect responsible for significant accumulations of snow. The basic idea is that cold arctic winds blow across these large bodies of water and pick up moisture. This moisture is deposited on the opposite shore, particularly if the land is considerably higher than the lake surface.
Lake effect snow storms tend to be very intense, especially if you happen to be caught in the middle of one of the bands. In fact, I was in just such a position only a few hours ago. It was very windy ("horizontal snow") and lake effect flakes tend to be very large and fluffy. Visibility was drastically reduced and I was lucky to see 100 meters in front of me at times. One particularly dangerous aspect of lake effect snow is its dependence on the wind direction. A slight shift and you can go from partly sunny skies to living in the heart of a snowman within minutes. If you are unfortunate enough to have a band stall over you overnight (i.e, wind keeps blowing but does not shift direction), you may wake up to several feet of fresh snow. It's kind of like having some monstrous skier's snow-making machine parked next to your house. On the plus side, those big, fluffy flakes are much easier to move than the dense little crystals we often see from storms which blow up from the south. That's like trying to shovel sugar.
While the bands are obvious over the western Great Lakes and Lake Erie, note the very thick band coming off of Lake Ontario (the most eastern lake) traveling due east. Underneath that big, fat, blob of green is the Tug Hill Plateau, one of the snowiest places in the lower 48 states. This area typically receives over 300 inches of snow per year. On the Tug Hill, the National Weather Service has a station at Montague which holds the 24 hour snowfall record for the lower 48 of some 77 inches. Yep. Nearly six and a half feet (almost two meters). I'm located just below that big green blob, just above I-90 (the obvious east-west highway that cuts the state in half). A few hours ago it was sunny, then it was white on white, and now it's sunny again.
You know, I remember a time about 20-30 years ago when lake effect snow only happened in November and December, and maybe, rarely, January.
And that's because, by February, the lakes had frozen over and weren't providing the water necessary to lake effect snow.
Geez, I wonder what's different now??????
This is (was) particularly true for Lake Erie which is relatively shallow, but Lake Ontario, being much deeper, never freezes over. We've gotten lake effect snow from November through April since I can remember.
Here's an even better image (after the front moved through) taken around 9 PM EST.