The perfect elixir for a tornado, a Texas Tech University associate professor says, is warm, moist air from the Gulf of Mexico coupled with a drop in elevation, even a slight decline, that creates a change in wind direction and wind speed.
Christopher Weiss, an associate profess of atmospheric science at Texas Tech, said those conditions “are critical for tornado-producing storms.” While Weiss studies the occurrence of tornadoes in the state of Oklahoma, which has the greatest number of tornadoes in the world other than areas of Bangladesh, the same conditions can form in the region.
“The fact that we are close to a warm body of water, we are fairly close to a mountain range and the fact we are at a latitude where we have the jet stream blowing over the top of us especially during the spring months fairly strongly — those things come together to give us a perfect recipe for tornadic thunderstorms,” Weiss said Thursday in a telephone interview from his office on campus.
These same conditions exist in western Ohio.
Todd Holsten, chief meteorologist of the National Weather Service office in Northern Indiana, told The Lima News in November he has his own theory about the increased frequency of tornadoes in the area. Similar to Weiss pointing to the drop of elevation from the Rocky Mountains to Oklahoma, Holsten points to the area around Bellefontaine, the highest elevation in Ohio, and the decrease in elevation to the Ohio-Indiana border.
According to USA.com, which ranks communities on a wide range demographics, it ranks Van Wert County as the eighth most likely county in the state for a tornado. It outranks Putnam County (31), followed by Allen County at 38 and Auglaize County at 47. These are all above the state average, while Hardin County at 53 is slightly below the state average for tornado activity.
Cloverdale in Putnam County was the site of a tornado in November. It had a maximum wind speed of 130 miles per hour and a maximum width of 440 yards. It lasted eight minutes, beginning at 4:55 p.m., and traveled 11.1 miles.
Cridersville in Auglaize County sustained straight-line winds and a downdraft in early July, and residents were victims of a tornado Oct. 26, 2010. Van Wert suffered a devastating tornado Nov. 10, 2002.
Weiss, who has researched the genesis and low-level wind structure of tornadoes for the past 13 years and maintains an interest in the processes responsible for the generation of the parent thunderstorms, said terrain can have a large influence. He cited the gradual decline from a high point can cause an increase in tornado activity, or a “tornado alley.”
“There have been a lot of studies that have looked at what is happening in a few counties up to a state in regard to terrain that can influence weather locally,” Weiss said. “There can be terrain features like an escarpment where the elevation drops a couple hundred meters, and that ends up being a significant feature meteorologically.”
Weiss, who grew up in the Detroit area, referenced the Irish Hills and the topography of the region contributing to the frequency of tornadoes, which is similar to the Bellefontaine area.
He said another factor can be bodies of water or a lake influence.
“Quite often people can see the development of weak tornadoes because storms run into the lake breeze boundary,” Weiss said. “It has been shown and it has been fairly well established like a lake breeze boundary can foster the development of tornadoes, especially weak ones and typically not huge ones.”
The lake breeze boundary is the land mass warms up more quickly than a body of water. The cool air above the lake which comes onto land is going to stop or slow down “much like a car stopping suddenly and the cars following colliding into the back of it and this effect creates upward motion.”
Weiss said “tornado alleys” can exist but to label an area as one would require a long period of data, at least 20 years or longer, to establish “an area as having more tornadoes than others because of terrain or climate but the lake breeze boundary we tend to see more of that activity.”
Speaking specifically about the late season activity, Van Wert and the entire area should be studied.
“These systems are occurring in a season where there typically is not a lot of high water vapor content because the air is cold, but these systems that race through are so dynamic that they have a lot of wind shear and this creates tornadic thunderstorms,” Weiss said. “It is amazing how often this is happening, but fortunately these events were fairly well predicted.”
By William Laney - The Lima News, Ohio (MCT)
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