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National Weather Service releases report on Lincoln County tornado

Posted: Updated: May 11, 2009 10:05 AM PDT

SPOKANE, Wash. - A National Weather Service team sent to investigate damage from Wednesday's severe supercell thunderstorm in Lincoln and Stevens Counties determined that an F0 (weak) tornado briefly touched down NE of Davenport Wednesday evening. In a report released following the investigation the NWS Spokane Office said that shortly before 7:00 pm the storm developed north of Odessa, WA in western Lincoln County. The NWS reported receiving several reports of funnel clouds and evidence of a tornado touch down 9-13 miles NE of Davenport with measurable damage along a four mile path moving toward Lake Roosevelt and the town of Ford.

A radar loop provided by the NWS showed storm activity over a 1.5 hour period starting at about 8 p.m. Wednesday. Several photos of the storm northeast of Odessa captured well-defined funnel clouds. The NWS said that based on the photographs it was hard to determine if this particular funnel cloud in fact made contact with the ground.  They said If there was evidence of debris spinning near the ground that would have lead to a tornado classification.

According to the NWS after the tornado dissipated the thunderstorm evolved into what meteorologists call a "bow echo". The "bow echo" gets its name from the radar which shows a shape reminiscent of an archer's bow. The term was first used in 1978 Dr. Theodore Fujita of the University of Chicago in research on supercell thunderstorm systems. Bow echo systems can produce severe straight-line winds causing severe damage. In fact according to the National Oceanic and Atmospheric Administration a strong bow echo can produce more widespread and intense damage than the majority of tornadoes. The Inland Northwest is not typically known for tornado and funnel cloud activity however the National Severe Storms Laboratory at the National Oceanic and Atmospheric Administration "since most thunderstorms produce some straight-line winds as a result of outflow generated by the thunderstorm downdraft, anyone living in thunderstorm-prone areas of the world is at risk for experiencing this phenomenon."

The straight line wind gusts from the bow echo moved east from Lincoln County into northern Spokane & southern Steven counties where the NWS team found area of wind damage about six miles long about five miles south of Deer Park. According to the NWS team at least two structures sustained significant wind damage from this part of the storm. They also believe that the high winds were responsible for uprooting dozens of trees in the same area.