FOR EXPERT COMMENT: Midwest Can Expect More Tornadoes, Severe Storms This Spring, MU Expert Says

March 8th, 2011

The views and opinions expressed in this “for expert comment” release are based on research and/or opinions of the researcher(s) and/or faculty member(s) and do not reflect the University’s official stance.

By Brad Fischer

COLUMBIA, Mo. – Midwesterners hoping for a calm stretch of weather after a cold, snowy winter might be disappointed. Tony Lupo, department chair and professor of atmospheric sciences in the College of Agriculture, Food and Natural Resources at the University of Missouri, says the approaching spring could be stormier than normal.

Lupo says the upcoming weather pattern is affected by La Niña, the same dominant atmospheric phenomenon that spawned this winter’s blizzards. La Niña occurs when cooler than normal water temperatures develop in the Equatorial Pacific Ocean. Lupo thinks La Niña will lead to increased spring and summer thunderstorm activity in states north of Tornado Alley, including Nebraska, Iowa, northern Illinois and Indiana. Tornado Alley is defined as North Texas, Oklahoma and Kansas.
The effects of La Niña are most noticeable in the winter, when it brings extreme cold to parts of the

nation. Lupo says that La Niña tends to shift the jet stream patterns northward over the U.S.  In a La Niña season, the jet streams pick up warm Pacific moisture and direct warm and unstable air to Nebraska, Iowa, Illinois and Indiana.  Storm systems and fronts tend to follow these streams.

“For a thunderstorm to develop, there must be moisture and warm air,” Lupo says. “When the jet stream is farther north, as it is in a La Niña event, you have a better chance of achieving these kinds of temperatures and dew points in these parts of the country.”

In Tornado Alley, Lupo forecasts a relatively calm year. Atmospheric models predict a dryer than normal spring and summer, taking away the fuel for supercell storms, which often spawn tornadoes.

Lupo received his doctorate from Purdue in 1995 and is currently the principal investigator at the Global Climate Change Group. The Global Climate Change Group investigates how global climate change may impact long-term weather patterns and the growing season in the Midwest. He has written 34 papers on factors that influence large-scale weather patterns. Lupo is also a member of the Intergovernmental Panel on Climate Change which shared the Nobel Peace Prize with Al Gore in October 2007.