Dear Tom,

I was watching a new television show about forest fires, and they were referring to dry thunderstorms. Is there such a thing?

Mel Shaftel

Dear Mel,

There is. A dry thunderstorm is a conventional thunderstorm in all respects, except that it produces no rain at ground level. Rain falling from such a storm evaporates before it reaches the surface. This typically occurs when thunderstorm bases are very high, (generally 8,000 feet or more above the ground) and when air beneath the storm is hot and dry. By comparison Midwestern thunderstorm bases average under 3,500 feet owing to higher low-level humidity. We’re fortunate that rain almost always accompanies Midwestern thunderstorms, but dry thunderstorms are a common summer phenomenon of the intermountain region of the western United States and High Plains in the lee of the Rockies. They are a huge problem because lightning ground strikes from such storms start forest and brush fires that are not extinguished by rain.

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