Tornado Season Off to Slow Start

(March 5) -- Last month was on the verge of becoming the first February in at least the past 60 years with no tornadoes reported, when one finally touched down on the 27th. The weak twister near Taft, Calif., caused no damage, and other than knocking February out of the record books, it did nothing to diminish the slow start of the tornado season across the United States. The relative quiet might continue through March.

According to a recent entry in the National Oceanic and Atmospheric Administration's Severe Weather Blog, the slow start means little or nothing when predicting whether the overall 2010 tornado count will remain lower than average.

From a purely statistical standpoint, that makes sense. February's three-year average is 78 tornadoes, which, while significant, pales in comparison to the peak monthly average of 305 tornadoes during May. One or two above-average months would quickly compensate for the slow start.

The lack of tornadoes, however, is a reflection of the current weather pattern, which might, in turn, give some guidance about whether this trend of fewer tornadoes will continue through March, a month where the three-year average of tornadoes increases to 138.

Tornado touches down in Riverside, Calif., on May 22, 2008.

Michael Ritter, AP

A tornado strikes Riverside, Calif., on May 22, 2008. The nation's tornado count was unusually low last month, but that doesn't mean the year's total will follow suit.

February was highlighted by numerous storm systems in the southern part of the country -- something that would result in frequent dangerous thunderstorms and perhaps tornadoes if the storms were to interact with unseasonably warm and humid air originating from the Gulf of Mexico. That part of the equation -- warmth and humidity from the Gulf -- was lacking. February temperatures were significantly below normal in areas along the Gulf Coast; in fact, on Feb. 12, snow was on the ground in every one of the 48 states in the continental U.S.

As we head through March, it appears that the active southern storm track will remain in place, but once again, the warmth and humidity needed for tornado formation may generally be lacking. The latest Climate Prediction Center 30-day forecast is predicting that temperatures will be below normal along the Gulf Coast.

CPC/NOAA

This is a recipe for fewer tornadoes than average, but this good news needs to be tempered by an understanding that March is different from February. With the same weather pattern, the potential for tornadoes is greater in March than it was in February. It's unlikely that the growing warmth of spring will not win the meteorological tug-of-war on at least one occasion despite temperatures likely averaging below normal along the Gulf Coast.

If a warm blast were to precede an approaching storm, then the always-dangerous tornado season would begin quickly -- even if the number of tornadoes is less than normal.