Stormy Weather July 18 08

It was one of these regular summer storms. It would get so dark that it looked all blue-black outside, and lovely; and the rain would thrash along by so thick that the trees off a little ways looked dim and spider-webby; and here would come a blast of wind that would bend the trees down and turn up the pale underside of the leaves; and then a perfect ripper of a gust would follow along and set the branches to tossing their arms as if they was just wild; and next, when it was just about the bluest and blackest—FST! it was as bright as glory, and you’d have a little glimpse of treetops a-plunging about away off yonder in the storm, hundreds of yards further than you could see before; dark as sin again in a second, and now you’d hear the thunder let go with an awful crash, and then go rumbling, grumbling, tumbling, down the sky towards the under side of the world, like rolling empty barrels down stairs—where it’s long stairs and they bounce a good deal, you know.

“Jim, this is nice,” I says. “I wouldn’t want to be nowhere else but here.”
—From the book Huckleberry Finn

I agree with Huck. There are few places I’d rather be than smack in the middle of a savage ripsnorter of a thunderstorm. I love a good storm.

I think most of us do. Weather is integral to the ambience of outdoor Michigan, and thunderstorms are all about ambience. The foreboding rumble of distant thunder; the malevolent scowl of an advancing arcus cloud; the sizzling intensity of lightning; the wet blast of the foreward-flank downdraft; the fresh smell of rain-washed air as the clouds roll off to the east…nothing grips the senses quite like a storm.

You know it’s true. When you were a kid, your mother told you to stay away from the window during a thunderstorm, didn’t she. But now that you’re grown, where is it you go when the thunder rumbles? Right—you head straight for the window. And who can blame you? A good storm is well worth seeing.

But not all storms are created equal. Here in Michigan, thunderstorms commonly line up in a squall line along an advancing cold front. Squall lines are prolific breeders of straight-line winds, intense lightning, and pea-size hail. Shorter squall lines may bulge out in the center, forming what is called a bow echo; the fiercest winds occur in these formations.

During the summer, warm air masses with mild winds aloft also favor single-cell thunderstorms that form and rapidly fade in the late afternoon. These popcorn storms are fairly benign diversions, and those with only an occasional, grudging flash of lightning practically beg you to take a walk in the rain.

On the other end of the spectrum is the supercell, the tornado breeder of the spring months. The isolated ones are the most dangerous, and relatively rare. More common in Michigan are supercells embedded in a squall line. Either way, forget about a walk in the rain. Think instead about a trip to the basement.

When a big thunderstorm is rolling in, though, chances are you’re not contemplating storm classification. No, you’re anticipating the experience. You’ve got a front row seat on a grand spectacle of the atmosphere, and the show is about to start. Overhead, a thin, milky canopy of cirrus has been gradually thickening over the past hour, deepening into gray. Above the distant hilltops, the skies look dark, and you can hear the first far-off mutterings of thunder.

(Look for part two next Friday.)