On Tuesday, March 25, the National Weather Service’s Storm Prediction Center upgraded the likelihood that the thunderstorm approaching western Washington will become severe.
“As of this morning, the Storm Prediction Center in Oklahoma upgraded a good chunk of Puget Sound – basically from the Everett area down through Olympia and into the southwest interior of Washington – into the slight risk category of severe weather,” Maddie Kristell, a meteorologist with NWS Seattle, told McClatchy in a phone call.
Perhaps more notably, the warning claimed that the storm “may produce large hail, a brief tornado, and locally strong gusts.”
“They’ve also, in the same area of the slight, got a 2% to 4% chance of a tornado as well,” Kristell said. “So it’s, on paper, a small likelihood, with the primary threats being more aligned with hail and strong thunderstorm wind gusts, we certainly can’t rule out rotation or spin up.”
How common are tornadoes in WA?
Tornadoes are rare in Washington, but they do happen occasionally. The Washington Emergency Management Division estimates that there are around two tornadoes in the state each year.
According to the National Oceanic and Atmospheric Administration, the state has seen 64 tornadoes since 2000, although 49 of those registered at EF0, the lowest level on the tornado magnitude scale. 13 reached EF1 and one reached EF2 on the one through five scale, while one was unspecified.
There have been 4 in Benton County. In western Washington they’re even less common. Thurston County has seen 4 tornadoes since 2000, most recently in 2019. Pierce County has seen five this century, but none since 2015. Snohomish County has had three, while King and Whatcom Counties have had one each.
Are tornado warnings common in WA?
So how rare are weather warnings that come with the chance of a tornado in Washington? Kristell said that this is the first time the Storm Prediction Center has upgraded a Washington storm to the slight risk category since the late 2010s.
“I believe the last one that was a similar analog to this may have been 2017,” Kristell said. “So it’s definitely not something that we see every season, every year.”
More often, NWS Seattle will issue a tornado warning. However, that only occurs when signs of a tornado have been reported or forecasting indicates one is imminent. According to Washington state’s Emergency Management Division, it’s difficult to detect tornadoes in advance in Washington due to the mountainous terrain, and they often form with little to no warning.
“The last time we issued a tornado warning here at the Seattle office was this past November. It was shortly after the bomb cyclone and wind event,” Kristell said.
Kristell said that NWS Seattle has issued 14 tornado warnings for western Washington in the past 20 years, the majority of those have been along the state’s Pacific coast.
Could WA see a tornado?
After the upgrade to the “slight risk” category, the odds of western Washington seeing a tornado remain low. However, while a tornado isn’t likely, Kristell said that the low pressure system causing the storm has the potential to behave in an unpredictable way.
“We’ve got a low pressure system offshore and it’s tilted negatively,” Kristell said. “So it’s kind of not standing straight up, but tilted more in an east-west direction, and that makes an environment that’s more favorable for storms to develop, and in this case, become more likely to be severe.”
What to do in a tornado
In the event that a tornado does hit, EMD recommends that you take these steps:
- Duck under something sturdy and as close to the ground as you can.
- Cover your head.
- Wait until the storm has passed before you leave.
EMD recommends going to the lowest floor of the building you’re in, ideally a basement, and finding a closet or a small room with sturdy walls.
If you’re in a car when a tornado is nearby, EMD recommends that you leave and try to get indoors. If you can’t, you should find a ditch, lie flat and cover your head.
