With yet another widespread cold air mass headed for the Midwest, Mid-Atlantic and New England later this weekend, it is time to update the positive aspects of this cool spring with regards to tornadoes. Indeed, tornado activity for the 12 months is now the lowest it has been in 60 years (since 1954) and the number of fatalities has dropped significantly since the very active 2011 severe weather season. Through Thursday, there have been three tornado related fatalities compared to two years ago when more than 500 people were killed as a result of tornado activity.
In terms of the number of tornadoes, the year-to-date count is approaching the lowest 10% of all years on record according to NOAA’s Storm Prediction Center in Norman, Oklahoma. Only three tornadoes have formed so far in the month of May which is usually the USA’s most active month, and all three were rated at the weakest classification level (EF-0). According to NOAA, April 2013 ended up with 83 official tornado reports as compared with 206 last year and 758 in 2011. March 2013 ended up with only 18 tornadoes as compared with 154 last year and 75 in 2011.
In terms of the cause of the quiet tornado season, the cold has been so relentless across the Rockies, Plains, South and East during the past couple of months that it has stopped in its tracks one necessary requirement for severe weather and that is the advance northward of very warm and humid air from the Gulf of Mexico. This upcoming cold air outbreak will send many places 15 to 20 degrees below normal for this time of year later this weekend and early next week and it will no doubt inhibit tornado activity during that stretch of weather.