> 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.