A couple times each year we get a (usually) weak tornado in our viewing area. That’s SW Washington down into NW Oregon and east into most of Eastern Oregon. They may be uncommon, but not unusual.

Back in March a weak tornado touched down near the mouth of the Columbia River, close to Ilwaco. That was an EF-0.

Last night a strong thunderstorm tracked through central Clark County. As it passed west of Battle Ground and then ENE to Yacolt, radar indicated some decent shear/rotation. The NWS issued a severe thunderstorm warning around 7:30pm, just as a tornado finished tracking through the area. Here’s the view at 7:35pm

Radar Default 2020.png

Soon after I heard from Tyler Mode, an avid weather “geek” and photographer from Battle Ground. He was watching the storm and recorded video of a tornado passing just north of the city. Check out his video…especially around the 1:10 mark: https://www.tylermodemedia.com/Weather/92721-Tornado-Battle-Ground/i-tKsZzwz Pretty exciting! Listen closely for the roar in the distance.

Shortly after seeing Tyler’s video, we received a great view from Gary Gerber. This video really shows the circulation, wind in the trees, and debris in the air. It doesn’t get much better than that in our area.

Once we saw these two videos it was obvious a tornado had touched down. The Portland NWS went out and did a storm survey today. Surprise! It was ANOTHER EF-0. This is from the NWS report

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Every tornado in our viewing area the past three years has been rated an EF-0. Note there have been no tornadoes so far this year in Oregon.

Recent Tornadoes.png

But we still have three months to go! And autumn has been a good time for tornadoes in our area. It’s interesting that mid-winter and mid-summer have the lowest chance of tornadoes; probably because we don’t get many showery patterns in July/August. And in mid-winter the showers are weaker, and thunder is rarer for inland areas.

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Of course, most of these tornadoes are weak. The vast majority the past 70 years have been in the EF-0 and EF-1 categories.

Tornado How Many Each Category.png

I often get two key questions about tornadoes:

Are there more tornadoes in the region than we used to see? Becoming more common?

The short answer is NO. Remember that 30 years ago almost no one was walking around with a camera attached to his/her hand (constantly). Now EVERYONE has a high-quality camera just a second away from use. Think about it; there’s a good chance that in pre-internet times, the storm in Battle Ground wouldn’t have been noticed except by a few homeowners wondering why part of the tree is across their lawn. And how many of them would have taken the time to call the Portland NWS office? There’s a reason that almost all reported tornadoes in the PACNW have been in populated areas. And the actual reported numbers have not increased dramatically either.

Is there some reason Clark County seems to attract tornadoes? A new “Tornado Alley”?

YES & NO. We have seen a couple of significant tornadoes in Vancouver (2008) and Battle Ground (2015) the past 20+ years. Those two were the most destructive. Other weaker tornadoes touched down in Salmon Creek (2017), Orchards (2017), east of Battle Ground (2013). The only deadly tornado on record in the Pacific Northwest was the F-3 that tore through Vancouver in April 1972, killing 6. A great study by Dave Elson at Portland NWS found that horizontal rolling of the southwesterly flow coming off the Tualatin Mountains (West Hills) may contribute to increased frequency downwind of that NW to SE topographic barrier as you can see in this image.


You can find his presentation here: https://www.ametsoc.org/chapters/oregon_archive/Minutes/2008/2008_11_20_Minutes_Powerpoint1.pdf

But no, there’s no new “tornado alley” developing in our area.

That’s it for now. Enjoy the (mainly) dry weather Wednesday. After more showers Thursday, October starts with 4-5 dry days.

Chief Meteorologist Mark Nelsen

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