Jun 5, 2008 11:01 pm US/Central
Good Question: Your Tornado Questions Answered
(WCCO)
Tornados inspire fear, wonder and for WCCO viewers, many Good Questions. Before a storm, why does the sky turn green? Why don't tornados hit cities? And why does the north metro seem to get hit by more tornados than the south?
Why does the sky turn green before a tornado? Anne, White Bear Lake
It doesn't always turn green, and it doesn't always mean a tornado is coming. But scientists believe there's a mixing of two colors. The sun typically gives off a yellow glow, and storm clouds are typically deeper than normal clouds, and full of water droplets. Water droplets typically appear blue. When the yellow of the sun shines through the blue of the water droplets, the sky turns green.
Why do tornadoes usually hit outlying suburbs like Anoka and not in Minneapolis? Sara Fitterer, Minneapolis According to the President of the Center for Severe Weather Research in Boulder, Co., it's not about urban heat islands or anything complicated. It's more about probability.
Major cities are small spaces. Downtown Minneapolis and St. Paul aren't much larger than a couple square miles. The odds of a tornado hitting those tiny targets is by one estimate, 1 in 1000 years.
Tornado alley, in the Midwest, has only about a dozen major cities. The rest of the land is rural. It makes sense that tornados tend to his outlying areas, as there's simply more geography to hit.
Tornados have come close to Minneapolis. Two hit Fridley in 1965 just five miles from downtown.
Why do storms seem to target the North Metro area of Minneapolis and St. Paul?
Minnesota Public Radio's
News Cut blog found some great information on this from
City-data.com.
The data is organized by percentage above the national average for tornado activity. Of course, everywhere in Minnesota is above the national average for tornados, as we are in the Midwest. Many states never have tornados.
The I-90 corridor in southwestern Minnesota is way above the national average for tornados. Albert Lea is 88 percent above the average.
The north Metro is in the 30 to 40 percent range above the national average. Brooklyn Park is 35 percent above average and Anoka is 31 percent above average.
The southern Metro has had more tornadoes than the north, according to City-Data.com. Apple Valley is 46 percent higher than the average and Lakeville is 48 percent higher.
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