2012 vs. 2011 tornadoes - Philadelphia News, Weather and Sports from WTXF FOX 29

What a difference a year makes. The 2012 U.S. tornado count through Tuesday September 25th is at 757. That's less than half of 2011's total of 1692. The months of October-December only average around 200 tornadoes. So even if the end of the year gets very active in terms of tornadoes, there's no chance 2012 will come close to 2011's count.

NOAA's Storm Prediction Center said that tornado events in the U.S. in 2012 have dropped well below the expected normal. The preliminary total of 757 tornadoes is about 400 tornadoes below what might be expected in a typical year. This chart shows that in late 2011, the annual running total was over 400 tornadoes above normal. This depicts the dramatic variability that can occur in tornado numbers from one year to the next.

The 2012 tornado season got off to an explosive start, with above normal activity into April. All of a sudden the jet stream or storm track lifted north and tornado frequency quickly died down. This was especially true over the summer as a huge heat dome of high pressure became established over the middle part of the country. As a result exceptionally dry conditions and drought affected a sprawling region from the Rocky Mountains to parts of the East Coast. This cut way down on tornado numbers.

But as the storm track shifted into Canada, our neighbors to the north became the new tornado alley. Canada experienced more tornadoes in July than the entire U.S., with Saskatchewan the new tornado alley:

Saskatchewan has had upwards of thirty tornadoes this summer, with most happening in July. In a typical year, there's an average of ten to twelve tornadoes in the province. What's more, Saskatchewan alone had the same amount of tornadoes in July as the entire United States.