You know a storm is pretty massive when it's in Eastern Washington, but can be seen throughout a wide swath of Western Washington.

But that was the case with a towering thunderstorm that formed just on the eastern side of the Cascade Mountains Monday evening.

Several people sent e-mails wondering what kind of cloud it was -- it's just a classic cumulonimbus cloud but admittedly they're pretty rare around here.

Eastern Washington does get these storms more often, but Monday night was a convergence of having the storm tower several miles high (radar estimated the top at 30,000-35,000 feet) and be located just to the east of the Cascade spine -- and at sunset to put a colorful palette on it to boot.

Here is what the storm looked like on radar, for your geographic reference:



The flat top -- otherwise known as the anvil -- is when the storm reaches a certain altitude where the temperature of the air rising air inside the storm is no longer much warmer than the air around it.

When that happens, the rising air stops rising and instead spreads out along this layer as if it's bumping up against an invisible lid. The appearance looks like a blacksmith's anvil and thus the name.