The forecast on Monday hardly featured a chance of thunderstorms in South Dakota. So when a tornado touched down in Watertown in the eastern part of the state, it surprised even a seasoned storm chaser.

Meteorologists said that just after 5:40 p.m., a “severe thunderstorm” that could generate a tornado was moving near Molalla at 50 mph, according to radar.

The National Weather Service issued the tornado warning for Northwestern Clackamas County in northwestern Oregon after a severe thunderstorm capable of producing a tornado was located near Molalla, or 17 miles south of Oregon City, moving northeast at 50 mph. The warning was cancelled just before 6 p.m. No damage has been reported.