There are a lot of benefits to living in a marine climate, and a lack of tornadoes is just one of them.
But while tornadoes are even rarer than a dry 3-day Memorial Day Weekend around here, they have made the occasional visit -- sometimes right even in the Seattle metro area.
The photo above, submitted by YouNews contributor Daaave, was taken of the F3 tornado that touched down in Kent on Dec. 12, 1969. Luckily, only one person was hurt and no one was killed.
"I remember the Kent tornado quite well," says Carolyn Walden. "I watched it from near where your photo (above) was taken (I worked at the Boeing Space Center down on West Valley Highway). It came in a northeast direction from near what was at least then called Midway, up on Kent’s West Hill, where my then-husband worked.
"The only real damage I remember was a billboard and a farm house (or one of its sheds or other outbuildings) right next to the Green River on the west side of the bridge that crossed the river on Kent-Des Moines Road (Hwy 516)... it was scary!"
Overall, only four* tornadoes have touched down in King County since records have been kept since 1880 -- three of them in the 1960s!
The first ever recorded tornado in the Seattle area struck the Sand Point neighborhood on Sept. 28, 1962 (just a few weeks before the great Columbus Day Storm!). Its wind speeds were clocked at 100 mph and was rated as an F1 tornado on the Fujita scale.
According to Historylink.org, the tornado damaged eight homes in Sand Point/View Ridge, then it turned into a waterspout as it crossed Lake Washington. The twister went all the way across the lake (what a sight that would have been had the 520 Bridge been built yet (1963)) and then made landfall again in the Juanita area of Kirkland, damaging more homes and toppling dozens of trees.
(In fact, there's an interesting anecdote on that Historylink summary that one person quoted in a Seattle P-I article back then as witnessing the tornado and experiencing damage at their Juanita home was Mary Gates -- the mother of Microsoft Chairman Bill Gates, who was 7 at the time.)
The third tornado (Aug. 18, 1964) and fourth tornado (June 11, 2001) were weak F0 tornadoes that didn't do any damage or cause any harm. (An F0 tornado that touched down in Buckley (Pierce County) in 2009 did stay on the ground long enough to get near Enumclaw (King County) but it's listed in the books as a Pierce County tornado.)
If we expand out to Snohomish and Pierce Counties, there have been quite a few more: Snohomish County has had 7 tornadoes, all since 1970 -- 2 F2s, 2 F1s and the rest F0s. That does not include the waterspout that touched down off Everett's shores last October that didn't hit land.
Pierce County has had five tornadoes -- earliest report in June 1978; most recent the one that hit Buckley on Sept. 6, 2009. Overall, four F1s and an F0.
Statewide, Washington averages about two tornadoes a year, most in the weak F0 to F1 category. That average recently was declared up from one a year -- most likely helped by our 1997 season that had a record 14 tornadoes.
Strong tornadoes need severe thunderstorms fed by large changes in temperature in the upper atmosphere. Severe thunderstorms typically need much colder air moving in aloft to make the air very unstable. The so-called "Tornado Alley" in the Midwest is ripe for severe weather due to frequent battles between cold, arctic air marching south of out Canada colliding with very warm, moist air moving north from the Gulf of Mexico.
But in the Pacific Northwest, the cool waters of the Pacific Ocean are a great moderating force that keeps temperature changes from being too drastic, and thus tornadoes are quite rare.
In fact, I don't think Western Washington has ever had an official Tornado Watch posted -- actually, I'm pretty sure we've never even had the lesser Severe Thunderstorm Watch. (Portland and Spokane, yes, but not Seattle area). We have had the occasional Severe Thunderstorm Warning and I can remember one tornado warning several years ago for Snohomish County -- that must have been the F0 reported on Aug. 25, 1997.
Has there ever been a bad tornado here?
Luckily what few tornadoes we have are weak and only four of them have ever officially injured anyone (including the aforementioned Kent one in 1969). There has only been one deadly tornado in recorded history in Washington -- an F3 tornado that touched down in Vancouver on April 5, 1972. Six people were killed and 300 were injured in that tornado.
What to do if there is ever another Seattle-area tornado?
One of my fears and wonders as a Seattle-area meteorologist is what would happen if we ever had a tornado similar to the ones that hit Kent and Sand Point in the 60s strike today. If we were to ever broadcast a tornado warning -- would anyone know what to do? Would anyone take it seriously?
I'd say if you have a few moments, just read this article on tornado safety tips. Odds are extremely low you'll ever need to use it around here, but just something to have in your brain bucket should a rare tornado ever appear.
The main points are: Get inside, and get as low and toward the middle of your home/building as possible. If you have a basement, even better.
We're lucky that the meteorological ingredients that create the massive, long-track destructive tornadoes that have done so much damage across the Midwest lately are nearly impossible to assemble in the Pacific Northwest, but history has proven that a tornado can form around here and at least be strong enough to do some damage.