mburchart-
frnash did a good job in his first post. What happens with some, but not all LES events off of Lakes Erie and Ontario (Ontario is the lake responsible for the big snows near Buffalo) is that when the winds blow from the WSW, they are able to travel over a long fetch (distance) of lake surface and pick up lots of heat and moisture. What also happens in some of these WSW LES events is that you get land breezes to form on both the north and south shores of the lake. They cause convergence of the air where the LES clouds/snow is occurring out over the lake and you get enhanced lift. All of these factors will lead to very intense bands of snow. Many times at 4-6"/hr. With rates like that, you do not need to have the winds change direction too fast to get lots of snow.
It is possible to get similar types of banding on the other Great Lakes, although they are typically much more rare. Not from the intensity standpoint, but because the banding typically does not last too long. Sometimes they will set up on the SE end of Lake MI and blow into far SW lower MI and/or NW IN. Intense banding can also blow off Lake Huron into portions of southern Ontario. I have experienced 2 episodes of 6"/hr snow here on the Keweenaw, although they only lasted around 20-30 minutes. I have also experienced several 4"/hr snows- that I have nicknamed "Bayfield Bombers" as the bands typically start just to the north of the Bayfield Peninsula and due to convergent winds cause a narrow, but intense band to hit the Keweenaw. Those have dumped 12-18"+ snows in a 24 hour period or less, but nothing even close to 6 feet!
A "once in a lifetime" snow event hit the Soo back in December 1995. A low caused some system snow to get strongly enhanced by SE winds off Lake Huron, then as the low passed off to the east of the Soo, the winds turned WNW and caused heavy LES to blow off of Superior. That was a multi-day event, but still produced just shy of 62" over the city and a depth of 50".
-John
