Tornadoes in Lincoln County - June 6, 2009

On the afternoon of June 6th, several people spotted tornadoes in northern Lincoln County, Washington. The most impressive pictures of the tornadoes were taken by Dawn & Chris Nelson. They live about 5 miles south of Creston, WA and snapped the picture below around 254pm. Initially only one tornado was visible, but it appeared to split into 2 twisters.

Mark & Wendy Rosman also saw 3 different tornadoes. While they live just a few miles west of the Nelsons, they never saw multiple tornadoes at the same time.

David Ross was traveling westbound on Highway 2 east of Wilbur. Around 3pm he witnessed a single tornado ahead of him and just north of the highway. It appeared to be nearly stationary and lasted several minutes.

These tornadoes were also visible from a considerable distance. Norm & Donna Leech spotted one from their location in Deer Meadows (see map below).

With several eye witnesses from several different locations, it helps to see all of this on a map.

Click on the red dots to see more pictures taken from that location.

While it's possible that the tornadoes witnessed by John Hardin and Norm Leech from Deer Meadows were different than those seen by residents south of Highway 2, it's likely that they were the same. Not only was the time the same, but looking at the map below, the location was likely the same.

The map below shows the likely viewing angle of the witnesses from Deer Meadows. This is based on the rock-island in the river on Norm's pictures (below left) which is also on the Google map below. Also, in John's picture (below right) the wooded hill in the foreground in Ferry County, while the steep rock face to the left is along south bank of the Columbia River. Based on these land marks, it's likely that the tornadoes were just east of Wilbur near Highway 2. These would probably be tornadoes #1 and #2.

So, just how many tornadoes were there? As of this writing, there are at least 4 confirmed tornadoes. Other eyewitness reports may still change this number, and if so, this web page will be updated to reflect that new information. Here's a recap of what probably was observed.

Tornado #1 touched down around 250pm and was initially witnessed by Kirby Dreger. This tornado moved to the northwest and out of her viewing site as it dissipated. John Hardin from Deer Meadows also saw this tornado eventually dissipate and then redevelop. This redevelopment probably took place near Highway 2 east of Wilbur and was witnessed by David Ross as he was driving from Creston to Wilbur. Once again, this tornado weakened as evidenced by David's last picture. Shauni Ross saw this tornado from her house in east Wilbur, but it was moving south.

Tornado #2 formed as #1 was redeveloping, as witnessed by John Hardin. This tornado took a similar track to #1, but Wendy Rosman saw it fall apart south of Highway 2. It is possible that this was the tornado witnessed by Shauni.

Tornadoes #3 and #4 formed shortly after each other, resulting in the "twin" twisters that were photographed by Dawn Nelson (from the southwest) and Shelly Sieverkropp (from the north).

So what happened to cause all of these tornadoes to form? If you click here, there is a large (6.6Mb) loop of radar imagery. In the loop you can see fine lines of light blue reflectivity before any of the convection develops. These are indication of convergent boundaries. There aren't any clouds associated with these boundaries. Rather, they indicate lines where the air is converging. During the afternoon of the 6th, winds were coming from the northeast over the Spokane area, while over the Columbia Basin, winds were from the southwest. Where these two opposing winds met, the fine convergent lines form. These convergent lines were responsible for the formation of the thunderstorms in the Columbia Basin.

On a smaller scale, the velocity data observed by the radar in the vicinity of the tornadoes showed a similar convergent boundary. In this image, green colors indicate winds flowing from left to right (i.e. winds from the southwest), while red indicates winds blowing from right to left (winds from the northeast). The solid yellow line indicates the approximate location of the boundary, where the northeasterly and southwesterly winds meet.

The tornadoes that form in this situation are known as non-supercell tornadoes. In a supercell tornado, the entire thunderstorm is rotating. This rotation begins in the cloud, descends out of the base of the cloud, and then touches the ground. For the non-supercell tornadoes, the circulation actually originates from near the ground, caused by the convergent wind boundary. This circulation is then pulled up into the the thunderstorm by the updraft, which is the air that ascends into a thunderstorm. While often the weaker cousin of the supercell tornado, they still are strong enough to potentially cause damage. In this event, all of the tornadoes were rated a strength of EF0 since no damage was reported.

Was the Weather Radar able to see these tornadoes? Unfortunately, no. The radar beam spreads out as it travels from the radar. By the time the radar beam reaches the Wilbur/Creston area (about 40 miles from the radar site), the beam has a width of about 3700 feet. From the estimates based on photos and eyewitnesses, the width of these tornadoes was generally 100-200 feet. Therefore, the radar beam would have seen both the incoming and outgoing portion of the tornado circulation, and thus would be unable to detect which way the wind was blowing, which is necessary for the detection of a tornado.

If you have any photos or reports of these tornadoes to share with the National Weather Service, please e-mail us at w-otx.webmaster@noaa.gov