East Wenatchee Tornado - May 19th, 2004

At around 4pm PDT on May 19th a strong thunderstorm produced a short lived tornado over East Wenatchee, Washington. The following pictures were taken and submitted by the Krausman family of East Wenatchee. The first photo shows the tornado as evidenced by the debris or dust and soil present near the surface. This likely was formed by a process similar to dust devils and intensified by the updraft of the thunderstorm. The second photo shows hail that was produced by this thunderstorm. Estimates from the photo indicate the hail is approximately 3/4 inch.

Post analysis of the event suggests this was an example of a landspout, or a non-supercell tornado in a weak wind shear environment. They are not an unusual occurrence; one was sited near Moses Lake just last spring. Essentially, a landspout forms when a broad, weak area of rotation in the low levels of the atmosphere is caught up in the updraft of a developing cumulus cloud or thunderstorm. The effect is similar to that of a figure-skater pulling in her arms to spin faster. As the area of rotation is stretched and constricts, it spins faster until condensation occurs and the funnel becomes visible. In this case, the landspout was in contact with the ground as seen by the debris cloud. Thus, by definition, it was a tornado.

Webmaster
US Dept of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
Spokane Weather Forecast Office
2601 N. Rambo Rd.
Spokane, Washington 99224

Tel: (509) 244-0110