Weather Blog

Storm clouds comin'



Tom Schonhoff sent in this great photo of storm clouds rolling in over Puget Sound with a state ferry below. You can submit photos through the YouNews section of our site and we'll showcase some of the best ones here on the blog.

Especially ones that can come with a good lesson on weather. For instance, this photo does a good job of illustrating a persistent problem in the Pacific Northwest -- false funnel cloud reports.  Many times we'll receive reports and photos purporting a funnel cloud dipping out of the cloud base. That wasn't the case here with Tom, who knew this was just a neat cloud. But the photo is a good example of a typical one we'll get with a false funnel cloud declaration. see how those jagged bottoms look sort of like a tornado in the making?  Instead, this is just called "scud" -- just a cloud with a ragged bottom.

The key to knowing the difference between scud and a true funnel cloud is to look for rotation. If the "funnel" is just drifting along or stationary, then it's harmless scud, which is the case about 99% of the time in the Northwest as funnel clouds are very rare.

We can, on rare occasion, get what are called "cold core" funnel clouds, which are tornado impostors. They have the look and feel of a developing tornado, but it's just some cold air spinning in a downdraft and rarely reach the ground. And even if they do, damage is minimal to non-existent because the wind speeds are comparatively very low.  They usually occur in the spring and fall when we get cold air moving in behind a storm that had passed either the night or day before. A Convergence Zone is also a good trigger for these events.

But that's not to say that the Northwest can't get a real honest tornado. Washington averages about one tornado a year somewhere in the state. They are almost always very weak -- especially by Midwest standards.  Washington has had only one deadly tornado in recorded history -- the April 1972 tornado that killed 6 and injured 300 in Vancouver, Washington. 

As for this storm pictured above? It probably managed to make a few who ventured out on the ferry's observation deck a little wet, but otherwise, just another passing rain shower.