The Inland Northwest has been dealing with a potpourri of interesting weather over the last couple of weeks. On May 6, a rare tornado was confirmed in Lincoln County, just northeast of Davenport, Wash. The tornado produced intermittent damage in a four-mile path from near Davenport toward Lake Roosevelt. The tornado was rated a 0 on the Enhanced Fujita scale, which assigns a rating based on estimated wind speeds and related damage. The scale ranges from EF0 to EF5, with associated three-second wind gust speeds ranging from 65 to 85 mph on the low end to over 200 mph on the high end. On average, both Washington and Idaho see only one to two weak tornadoes each year.
In addition to producing a tornado, that same storm evolved into what’s called a “bow echo” as it moved into Stevens County. The name bow echo comes from the fact that the storm takes on a bowed shape on the radar image (whereas a tornado is associated with what’s called a “hook echo” on radar). Storms that evolve into this bowed shape have the potential to produce damaging straight-line winds with speeds of 100 mph or more. In northern Spokane County, just south of Deer Park, a narrow six-mile swath of roof damage and uprooted trees was reported.
Fast forward one week, and it’s not severe thunderstorms we’re dealing with but rain, graupel, cold and the ever annoying wind. Folks who thought they had waited long enough and put in their veggie gardens last weekend, held their breath as temperatures in a few locales across Eastern Washington and North Idaho dipped below freezing. Morning low temperatures on Wednesday included 37 degrees at the Coeur d’Alene airport, 33 at Spokane’s Geiger Field, and 37 at Felts Field in the Spokane Valley. Some locations that did fall below freezing include Priest Lake with 30 degrees, Colville with 30 degrees, and Fairchild Air Force Base which dropped to 31.
Speaking of cold, May has definitely started out on the cool side, with average temperatures about 3 degrees below normal overall for the first half of the month. La Niña, the cooler-than-normal waters across the equatorial Pacific which are associated here with cold, snowy winters, and cold springs, is officially over with as of last month. Sea surface temperatures are now reflecting neutral or “La Nada” conditions. The Climate Prediction Center forecasts this scenario to continue throughout summer, which translates locally into a warmer and drier than normal summer.
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