All summer the waters of seas and lakes have been sucking up the heat of the sunshine, and now that the sunshine is gone or greatly reduced, those open waters return that heat to the air. They are like radiators to our north, warming the arctic blasts as they head for us. They spare us the worst cold, until they freeze over. (Even when they first freeze over, these waters continue to radiate lesser amounts of heat while the ice is thin. Ice that is only six inches thick radiates roughly eight times as much heat as late-winter ice that is four feet thick, if I remember correctly.)
The above map and chart show that last year the Great Lakes were warmer than normal, but this year they are colder than normal. Here in New England we are that much less protected than we were last year.
This does not mean the Great Lakes will freeze over as badly as they did last year. The lakes seldom freeze over so completely two years in a row. However it does suggest the ice will start to form earlier than it did last year, with the water six degrees colder to begin with. The west and northwest winds will be colder, in New England, as the winter begins.
After that all depends on the pattern that develops. NOAA suggests an ordinary winter, however over at the Weatherbell site the excellent long-range forecasters Joseph D’Aleo and Joe Bastardi are suggesting a sort of worst-case-scenario may occur.
A worst-case-scenario would have a flow from the north, filled with Siberian air supplied by a cross-polar-flow, again pouring south over the Great Lakes. We would witness the rarity of the lakes freezing nearly completely two years in a row, and consequently New England will face extreme cold.
Hope for the best, but prepare for the worst.