Beware of Young, Innocent-Looking Cumulus Clouds

The building stage of a thunderstorm is usually the most dangerous.

Some things never change, and the danger of flying into the wrong thunderstorm is one of those things. In Bob Buck's superb 2002 memoir, North Star Over My Shoulder, the veteran pilot recalled flying a B-17 Flying Fortress all over the globe seeking out convective activity and performing research for the military on thunderstorms and static discharge within the atmosphere. An inspirational writer as well as a historically great pilot, Buck died last year in his 90s. His recollections from the 1940s are as vital to pilots today as they were to the wartime aviators for whom the research was intended. Starting with a quote from his wartime logbook, he then added parenthetical insight from subsequent years' experience:

"Flew through a small shower near Mt. Pocono, Pennsylvania, top estimated at 15,000 feet-innocent looking, but very high [static] fields and very, very rough." (This was probably a thunderstorm in the process of creation. This, we found, is the time the turbulence is often strongest, the primary stage of a thunderstorm. Lesson: don't think a pretty, white cumulus cloud building is innocent; it may pack a very hard punch.)

An addendum for today's Nexrad-enlightened pilots is, don't lose sight of the fact that your radar picture is at least four or five minutes old; that can be plenty of time for one of Buck's "small showers" to lose its youthful innocence and turn on you like a bare-knuckle boxer. The radar picture is an invaluable strategic tool for avoiding areas of intense weather, especially if you use the animation feature to track the building and movement of precipitation returns. But when conditions are prime for thunderstorm development, never count on a clear screen as a money-back guarantee of calm sky.