Area lacks key ingredients for severe storms

Severe weather, including numerous tornadoes, devastated parts of Kansas last weekend. The deadliest tornado struck Greensburg on May 5, flattening nearly the entire town and killing at least 10 people. Winds were estimated at 205 mph, and the twister carved out a 1.7-mile-wide track that was 22 miles long.

The damage that it produced, leveling homes and other structures to their foundations, was given an EF-5 rating. The tornado damage rating scale, the Fujita scale or “F-scale” was recently updated and renamed the EF-scale or Enhanced Fujita scale to better correlate wind speeds with structural damage. Based on damage surveys, the strongest tornadoes, such as the one that hit Greensburg, are given an EF-5 rating. The only other EF-5 tornado that has struck in recent years was the May 3, 1999, Moore, Okla., tornado.

In Idaho, the two most damaging tornadoes were EF-3s which occurred in Nez Perce County in June 1936 and later in Gem County in April 1940. While Kansas sees an average of 55 tornadoes per year (ranking third behind Oklahoma and Texas), Idaho averages only three. In fact, the last tornado to strike the Panhandle occurred nearly three years ago in June of 2004.

The main reason North Idaho has so few tornadoes (or any severe thunderstorms for that matter) is that the necessary ingredients for severe weather do not come together very often. To set the stage for powerful thunderstorms, you need three things: moisture, instability, and lift. All three serve to cause the intense rising air motions which fuel the storms.

Some thunderstorms did roll through the parts of the Panhandle south of Interstate 90 this past Tuesday. This came on the heels of the warmest day of the year so far, with temperatures soaring into the summerlike 80s. No records were broken, though Lewiston did reach a scorching high of 93 degrees. Coeur d’Alene’s record high of 90 degrees for May 8 (set in 1949) was left untouched when the city topped out at 83 degrees.

The warm day was a testament to spring’s wild fluctuations, as just four days earlier, wet snowflakes were reported in the area. Though the past week’s mild and mainly dry weather has been pleasant, more rain is needed this month as Coeur d’Alene has seen only .41 inches of rainfall in a month that averages nearly 2.25 inches.