Impostor! Despite its looks, that was no tornado in Maple Valley this weekend

A likely "scud" cloud spotted in Maple Valley, Wash. on April 28, 2018 (Photo: Mark Taeschner)

It was a rather stormy day Saturday around the Puget Sound region, with some storms churning out heavy rains and even some interesting-looking clouds that had looked a little like we should be calling out to Aunty Em.

But they were not tornadoes, or even funnel clouds. Instead they were likely "scud" clouds -- harmless clouds that nonetheless sometimes attempt their best impersonation of a tornado.

Especially in the spring, when the air mass is unstable and we get those billowing clouds that bring heavy showers and a few bolts of lightning, these types of cells do tend to have a ragged cloud base with "strips" of clouds that can sure look like a funnel at first blush.

But 99 times out of 100, and perhaps even more frequently, these are harmless "scud" clouds. NOAA defines them as: "Low ragged and wind-torn appearing cloud fragments, usually not attached to the thunderstorm base, often seen in association with, and behind gust fronts. Scud clouds DO NOT produce severe weather. Scud clouds are often mistaken for wall clouds and tornadoes, especially when attached to the thunderstorm base."

And that's likely what happened in the photo above that looks quite tornadic. However, the National Weather Service office in Seattle confirmed radar data showed no rotation at all either in Maple Valley or the surrounding area during the 6 p.m. hour when that photo was taken. Instead, this was a bit of an optical illusion where one of those cloud fragments floated into a spot where it looked like it was attached to a base and a full-fledged funnel. (There was no sign of an actual tornado touchdown in the area, either.)

But it wasn't just in Maple Valley where the clouds were playing tricks. This video from Edgewood on Sunday has a little funnel imposter.

And over in Bremerton, an ominous cloud formed (that did have a little bit of rotation indicated in the radar, but not a lot) and brought another suspiciously looking funnel cloud imposter. But again, it wasn't a funnel -- it was a "tail cloud" that forms in an area where there is inflow into a storm. Jessica Lewis captured it on film:

Looks scary; ultimately harmless.

How to know if a cloud is just scud or a budding funnel? Three words: Rotation, rotation, rotation. A truly developing funnel cloud will have tight rotation forming and also be attached to the base of the cloud.

Like this:

Scud clouds tend to float aimlessly just below the clouds or not really attached.

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