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The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

Spring finally brings warmth to region

Michelle Boss Correspondent

We are finally getting our first really good taste of warm weather across the Inland Northwest. Fortunately for us, the warmth has been accompanied by sunny skies or otherwise benign weather conditions. Across much of the nation east of the Rockies, however, springtime warmth has also been accompanied by deadly severe weather.

So far this year, there have been tornadoes reported in 27 states. Last weekend, 22 people were killed in tornadoes that swept across Oklahoma, Missouri and Georgia. During the first week of February, the death toll was even higher with 57 fatalities attributed to 82 confirmed tornadoes across the lower Ohio Valley and southern U.S.

The only tornado reported west of the Rockies occurred when a rare winter tornado swept through Vancouver, Wash., on Jan. 10. Fortunately no injuries were reported, though there was widespread damage.

With no other severe weather reports (large hail, damaging winds, or tornadoes) across either Idaho or Washington this year, can we consider ourselves more or less immune to the warm season’s most dangerous storms?

Although tornadoes are rare in the this part of the country, they can and do occur. Idaho averages three tornadoes per year while Washington and Oregon average two each. Contrast this to the yearly average of 139 tornadoes in Texas (though you have to consider the large size of the state), 57 for Oklahoma, and 55 for both Kansas and Florida. The tornadoes that do occur in this region are usually not as strong as those east of the Rockies.

Tornadoes are ranked on a damage scale called the EF-scale or “enhanced Fujita” scale, named after meteorologist and famed severe storms researcher Ted Fujita of the University of Chicago. The scale goes from EF-0, designating the weakest tornadoes which result in only minor damage, to EF-5 – tornadoes that can level homes down to their foundations. Though windspeeds are associated with each of the rankings, the ranking is based on damage alone, as it is nearly impossible to directly measure the windspeed of any given storm.

In Washington and Idaho, the strongest tornadoes on record were both EF-3s. One of three of these strong tornadoes in April 1972 proved deadly for six people in Clark County, Wash., with 300 people injured. In Idaho, the two EF-3s on record occurred in Nez Perce County in June 1936 and in Gem County in April 1940.

In the U.S., only two tornadoes on record have been given the EF-5 ranking. These were the Greensburg, Kan., tornado of May 2007 and the Moore, Okla., tornado of May 1999.

The main reason that the Northwest sees so few tornadoes (or severe thunderstorms for that matter) is that the necessary ingredients for these strong storms do not come together often. To set the stage for powerful thunderstorms you need three things: warm moist air, instability and lift. All three serve to cause the intense rising-air motions which fuel the strongest storms.

The “dry heat” we experience during summers is not conducive to severe thunderstorm formation. What we more often have to deal with, however, are potentially dangerous and damaging “straight line” (nontornadic) winds that can occur ahead of an approaching storm. It was this particular setup that resulted in the record breaking 77 mph winds recorded at the Spokane International Airport in June 2005. Damage from this storm included downed trees and power lines, and 28,000 people lost power across Eastern Washington and North Idaho.

If your home is ever in the path of potentially damaging straight line winds or tornadoes, the safest place to be is in a basement or interior room away from windows.