News and Tribune

March 3, 2013

Traditional severe weather season expected

March, April and May remain the hot months for tornadic activity

By DANIEL SUDDEATH
daniel.suddeath@newsandtribune.com

> SOUTHERN INDIANA — Weather experts concede it can be nearly impossible to forecast days or weeks ahead of time where an individual storm or tornado will strike. 

But predictions are made about weather patterns, and that information can help forecasters determine the likelihood of tornadic activity threatening a specific area. 

As opposed to recent years, 2013 is predicted to be more of a traditional season in terms of severe weather in the area according to Joe Sullivan, warning coordination meteorologist with the Louisville bureau of the National Weather Service. 

Tornadoes and severe weather struck the area during winter months in recent years, but it looks like March, April and May will be the most likely months for formidable storms in 2013, Sullivan said. The change in temperatures from winter to spring provide the conditions for severe weather, he said. The transition between seasons normally creates instability in the air that can trigger tornadoes and severe storms, Sullivan continued. 

“Traditionally the biggest storms occur when there’s a big transition from warm to cold weather or vice versa,” he said. 

Warm air at the surface and cold air aloft, moisture and a triggering mechanism such as a cold front are the conditions needed to produce severe weather, Sullivan continued. Such conditions are more likely during transitional seasons, and those time periods are usually when super cell tornadoes such as the one that struck Henryville last year occur, he said. In the area, the jet stream is typically further north during the summertime, so storms are usually shorter lived and less strong than those of the spring, Sullivan said. 

A plethora of unstable air, upper-level changes in the atmosphere and a warm front helped spawn the deadly Southern Indiana tornadoes last year, he said. This year, Sullivan said March is predicted to have higher-than-average temperatures and above-normal precipitation. 

“Taking the generalities in that, you’d say we’re probably going to have closer to a typical severe weather season, which hasn’t been typical around here in recent years,” Sullivan said. 

Weather experts may not be able to tell you if a tornado will strike in Floyd or Clark counties a month from now, but when a threat for severe weather is discovered, their forecasts could save your life. 

If severe weather is predicted for a specific area, people shouldn’t just wait to hear a tornado siren or listen to their weather radios, he said. 

“The best way to find out if you’re in danger is to watch the television stations or get online so you can see the path [of the storm] and where it’s headed,” Sullivan said.