A series of funnel clouds spotted in northern Lincoln County during an intense thunderstorm last Saturday have been classified as the lowest level of tornadoes by the National Weather Service.
Four funnel clouds formed along a boundary line between colder Canadian air that moved from northeast to southwest across the region and a milder air circulation moving from south to north. The line where the two air masses met, or the convergence area, triggered the funnel clouds, according to the weather service.
Those funnel clouds about 3 p.m. began on the ground, much like dust devils, and were drawn skyward by the updraft of the thunderstorm set off by the collision of the air masses, the weather service said.
That type of tornado is different from the more destructive variety often seen east of the Rocky Mountains in which twisters descend from a rotating supercell thunderstorm. Those tornadoes have distinctive features that are visible on radar as well as from the ground, facets that were lacking in the Lincoln County tornadoes on Saturday, meteorologist said in a report issued Wednesday.
The Saturday tornadoes in grain fields south or U.S. Highway 2 between Creston and Wilbur caused limited damage and were classified at the lowest level, zero, on the Enhanced Fujita Scale (EF0).
Under the scale, wind gusts could reach 65 to 85 mph in an EF0 tornado.
The thunderstorm was centered northwest of Sprague in Lincoln County. It dropped hail of one inch in diameter at the west side of Sprague Lake and caused flooding across a rural highway northwest of Sprague.