What is a "Wet Microburst"? The cause of the stormy mayhem in Thurston County

Thurston County took the brunt of the damage from the system of powerful thunderstorms that moved through Western Washington on Thursday. (Photo: KOMO News)

Much of the I-5 corridor was hit with some semblance of thunderstorms Thursday, but Mother Nature kicked it up a notch in Thurston County.

Well, maybe make that two notches. Or three. Or 100…

Videos from Lacey, Olympia and Yelm showed an incredible seen of unbelievable torrential rains and amazing winds that looked like something Hollywood simulates for being in the middle of a hurricane. Turns out, that wouldn't be all that far off.

One particular cell among the many thunderstorms roaming around was so strong, it triggered what's called a "wet microburst".

It's when a cloud essentially lets go of a massive amount of rainfall that would be akin to taking a several hundred yard-wide diameter water balloon, and dropping it on the region. (Watch this video from Bryan Snider in Arizona to see what I mean.)

As the "water balloon" (but really: Just very intense rain) hits the ground, it spreads out in, creating a sudden and intense wind along the surface. The result is a freight train of wind and rain that can cause instant flooding and wind damage.

In Thurston County's case, the National Weather Service office in Seattle says based on damage and witness videos, they estimated the downburst winds likely in excess of 70 mph!

As for some of the damage: Several cars were trapped when strong winds toppled trees and power lines along Yelm Highway between Wiggins and Corporate Center Loop.

Some drivers were trapped in their cars for more than two hours until the live wires could be dealt with.

PHOTOS | Thurston County Storm Damage

About half a mile away, a tree nearly split a home in half in the 2500 block of 25th Loop SE. And several parked cars at a Lacey grocery store didn't stand a chance and were crushed by falling trees.

About 45,000 people lost power -- the majority in Thurston County.

The National Weather Service storm report read like a laundry list: Large tree down on apartments in Olympia. A large tree onto a truck in Olympia, numerous trees and power lines down on Olympia's Rich Road.

As for heavy rains, Observers with the CoCoRahs volunteer spotter netowrk reported anywhere from 0.99" to 1.26" with the storms Thursday -- most of that probably coming in less than an hour or so.

Wet microbursts are particuarly dangerous for aircraft as it can cause a sudden downward force. Luckily no such issues Thursday and those that were caught out in that can take solace that these type of events are exceedingly rare around here!

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