April without a tornado: unusual but not ‘rare’Published 3:17pm Thursday, May 10, 2012
While April can be an active month for severe and destructive weather in Alabama, the state didn’t have a single report of a tornado or even a tornado warning.
Having an April without a tornado is unusual, but it turns out that it isn’t exactly “rare” either, according to Alabama State Climatologist John Christy.
In the Doppler weather radar era, which started about 1992, the state has seen four tornado-free Aprils — 1993, 2001, 2004 and, now, 2012. In the 50 years before Doppler radars were installed around the country, Alabama had 11 Aprils without tornados, so pretty close to one April out of five before and after.
Of course, a number of tornadoes that would be counted now weren’t in years past because we had neither the radar hardware nor the network of trained storm spotters that we have now, Christy noted.
“A month without tornadoes was the good news from April,” said Christy, who is also a professor of atmospheric science at The University of Alabama in Huntsville. “Unfortunately, the weather systems that kept Alabama free from nature’s most violent storms also pushed away most of the rain. About half of the state saw less than 50 percent of its normal rainfall in April.”
The portion of Alabama designated as being in a drought more than doubled in April, from 42 percent on March 27 to almost 91 percent on May 1. Nearly all streams in the state are well below their average flow for this time of year, some in the one-in-100-year lowest level. The U.S. Army Corps of Engineers has started drought operations on the Chattahoochee and Appalachicola rivers, trying to maintain at least a minimum flow.
With the La Niña Pacific Ocean cooling event all but gone, however, any prediction for weather in May and the summer months should be taken with great caution, according to Dr. Christy. “That is especially true since May can have all sorts of weather, everything except winter storms and hurricanes. In May we have seen floods and droughts, heat waves and cool, hail, high winds and tornadoes.”