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The Dandelion Says Go Home

Do-it-yourself meteorology, as taught by the flora and fauna
By Steven M. Krauzer

What’s the best way to predict the weather when you’re in the backcountry? “Carry a radio,” says Peter Felsch, a meteorologist with the National Weather Service. Makes sense. A dedicated receiver tuned to NWS forecasts costs about $40, weighs less than a pound, and can warn you of any impending threats over the next one to three hours. But
like any technology, the weather radio is only a tool. Batteries die, reception can be spotty, and for most of us, self-sufficiency is the point of being out there in the first place. Which means using your senses and natural phenomena to gauge Mother Nature’s short-term plans.

Temperature. Rapidly falling mercury levels portend stormy conditions, so keep aware. If you don’t have a thermometer, try counting the chirps a cricket makes in one minute, subtract 40, divide by four, and then add 50–that’s the approximate temp. Two other handy indicators: Dandelions close up below 51 degrees, and your breath becomes visible at
45.

Wind. You can estimate a breeze’s speed and direction by watching which way and how forcefully it blows the surrounding branches, leaves, and grass; know, too, that clover shuts when gusts exceed 20 miles an hour. Pay particular attention to sudden, counterclockwise shifts in wind direction, especially those that move from north to south, which
often mean an approaching storm.

Humidity. Perhaps the most accurate harbinger of a really nasty thundershower, humidity is none too hard to determine when humping your pack–your rate of perspiration speaks volumes. But it’s less easy to estimate when you’ve stopped for a break near a stream or to take a dip in a mountain lake. For such times, keep in mind that frogs croak more
frequently in muggy weather–the increased humidity enables them to stay out of the water longer–and the scarlet pimpernel, long dubbed “the poor man’s weather glass,” folds its petals when humidity levels exceed 80 percent.

Pressure. Low barometric readings tend to indicate imminent rain. So look for bubbles forming around the rim of your coffee cup and campfire smoke hovering close to the ground–both occur when the barometer is falling.

Finally, if you want to approach do-it-yourself forecasting a bit more seriously, consider carrying a two-part “weather kit,” consisting of a Casio Pathfinder Triple Sensor wristwatch ($170; 800-962-2746), which displays temperature, altitude, and barometric pressure; and a chart to help you interpret the raw data. You can find the latter by pointing your Web browser to
www.usatoday.com/weather/wfbarrow.htm.

Illustration by Ross MacDonald