Northern Hemisphere snow cover is running well above normal on this Halloween 2012, as recent building of snow across Canada and northern Russia adds to the above normal count.
You're probably thinking: Why should I care about Siberia?
Well, studies have proven that October snowfall in Siberia correlates well with winter conditions in North America. These studies have shown that, in above normal snowfall cases in Siberia, a negative Arctic Oscillation, or AO develops. This negative AO provides a base for cold air to drop into the United States. In a positive AO, warm air holds its ground in the Lower 48.
However, it appears that only October matters for this theory. Last year, snowfall was below normal in October yet above normal in November. As the studies indicated, warm air was then favored across the Lower 48, and this forecast did indeed verify.
Now, in October 2012, we found ourselves with the following:
-Slow start to snow cover in early October
-Gradual building of snow cover in mid October
-Burst of snowfall in late October
If we apply this to the correlation with the Arctic Oscillation, one would think that this winter will start out on the warm side, before gradually turning cooler. Late in the winter, it would be expected that a very frigid air mass would enter the United States and make for a brutal end of winter. However, because this is just one puzzle piece in an extremely complicated puzzle, this is in no way set in stone, nor is it my forecast. This is what would be expected to happen if this theory were the only factor that forecasted this winter.