Tornadoes 101: The basics
Getting familiar with this weather phenomenon.
Tuesday, March 15, 2011 - 13:15
STORM SEASON: It's on the horizon. (Photo: PedalFreak/Flickr)
The recent natural disaster in Japan reminds us all of just how staggering a visit from Mother Nature can be, even if we are prepared for it. In the Midwest, we witness a wide range of temperature problems and are sometimes held captive by extreme colds or heat waves that can be life threatening. Blizzards humble us and can shut down entire states with their ferocity. Flooding is always a concern, with the area on alert again this spring to see if higher temperatures will unleash runoff into the major rivers that cannot be contained, especially after the record breaking snows this winter have already raised the water levels.
But while these phenomena cause the most deaths and destruction, Americans are fascinated with the ravaging storm systems that appear in spring and bring on the T. rex of land storms: the mighty tornado.
Tornadoes occur when cold and warm air collide, most often during seasonal changes in the spring and fall, although they can find us at anytime of the year. Illinois witnessed a rare winter tornado on Nov. 22, 2010, as temperatures that week fluctuated between the 40s and 70s. They spawn from supercell thunderstorms and extend from clouds as the familiar, funnel-shaped menace with winds that can reach 300 mph and decimate everything in their path.
While most tornadoes follow some general rules, others color outside the lines and follow their own schedule. For instance, the majority occur in the evening hours, from 3 p.m. to 9 p.m., as this is the period of peak atmospheric heating and offers good fodder for storm systems. But that doesn't mean a funnel cloud won't come knocking at 6 a.m. Often tornadoes are preceded by very dark skies, sometimes with a greenish tint. They frequently accompany thunderstorms that produce hail and have low-lying clouds, especially if those clouds are rotating.
One of the best non-visual warning signs is the noise a tornado produces. If you are inside and not paying close attention to the storm, you don't have much time left to find safety if you hear the tornado barreling toward you like a freight train.
Illinois has hosted many of these beasts over the years, none more famous than the 1925 Tri-State Tornado that is listed as one of the worst natural disasters to strike American soil. Over 15,000 homes were destroyed when this storm system attacked Illinois, Indiana and Missouri, causing F5 damage and leaving 700 dead. Our state was also part of the biggest outbreak of tornadoes in April 1974. With 147 tornadoes touching down in 13 states and parts of Canada, this storm system blew out the record of 115 tornadoes caused by Hurricane Beulah in 1967.
For a lot of interesting facts about tornado science and the history of these storms, visit the Storm Prediction Center's website.
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