Ice on Great Lakes Vs. Snow

Heavy lake-effect snow will continue to be a problem this week for the Oswego area of New York State. Why there and not so much in Erie? Well, the Great Lakes still remain mostly ice free today, except for Lake Erie, which is completely frozen over.

Since the cold air won't encounter warm water, but rather cold ice, lake-effect snow will not happen (for a complete explanation of how lake-effect snow forms, see "Lake-Effect Lasagna").

Here is an image from the NOAA GLERL site, showing how much ice is on the lakes today. I have reversed their color scale here so the map is easier to understand.

You can actually see the ice-covered Lake Erie in this NASA camera-like visible satellite shot from Saturday:

The unusually warm December and early January kept the lakes much warmer than they would usually be, creating a ticking time bomb of pent-up lake-effect madness, which went off last week, bringing 146 inches of snow to one location east of Lake Ontario.

When did Lake Erie freeze over and why? It looks like it froze over during the first week in February this year (from this animation which you can open in Quicktime). Normally it happens before the end of January. The reason that Lake Erie freezes first is that is shallow compared to the other lakes (NWS-BUF). Last year's extended January warmth and relatively warm February kept the lake from freezing over until March, according to the animation mentioned above. This caused an extended lake-effect season for both lakes in 2006. That late freeze was close to the previously established record set between 1973 and 2002 (see image below, obtained from here).