How to Make Your Own Weather Forecast

I used to hunt elk with a cowboy named Ettinger who’d had his skull kicked in by a rodeo bronc. He could tell when it was about to snow because the decreasing atmospheric pressure caused the gases in his head to expand, which pressed against the metal plate in his skull and gave him a headache. Most of us (luckily) don’t have anything like this to rely on. Instead, we adjust a radio dial or click a mouse. But if we pay attention to nature’s forecasters–clouds, stars, and barometric pressure–we may be rewarded with information that’s more accurate.

READING THE SKY
Speaking broadly, the higher the cloud cover, the better the weather. Start worrying when clouds combine and the sky turns milky. Mare’s tails that resemble apostrophes and mar an otherwise clear sky precede precipitation by up to 15 hours, giving, say, an observant antelope hunter enough time to get out of the badlands before rain turns the dirt roads into gumbo. A “mackerel sky” of overlapping altocumulus clouds is also a reliable long-range forecaster of souring weather. (To learn more about what cloud formations herald, see Sportsman’s Notebook, February 2004.)

Halos around the sun or moon are caused by ice crystals refracting light; they often presage an approaching warm front. Precipitation may not follow, but the brighter the circle, the greater the likelihood, hence the proverb–“Halo around sun or moon, rain or snow soon.” A red moon caused by dust pushed by a low-pressure front also portends rain.

PRESSURE POINTS
Barometric pressure is another key to predicting weather. My friend Ettinger’s headaches were a result of the same principle that causes swamps to stink more before rain–as pressure drops, the methane trapped on the bottom releases in greater quantities. Sounds such as birdcalls or the ringing of an axe also become sharper prior to stormy weather, as low-lying dense air causes sound waves to bend back toward the earth. And campfire smoke stays low.

Conversely, high pressure dissipates scents and sounds and allows smoke to rise. With high pressure, dust particles suspend at higher altitudes, turning the moon and sky hazy. When the next low-pressure system advances, those particles fall toward the ground, and the moon and the mountains loom large and clear.

Will knowing about mare’s tails and moon halos help you fill a deer tag or coax a trout to open its mouth? Maybe not. But by paying attention, you will have traveled closer to the heartbeat of nature, which is hunting and fishing’s truest reward.

ANIMAL ORACLES

FACT OR FICTION? Animals are excellent forecasters, but there are as many myths about their abilities as truths. Do you know which of these sayings are accurate and why?

–Swallows high, staying dry; swallows low, wet will blow.

Fact. In good weather, high-pressure systems carry insects aloft on warm thermal currents, making birds fly higher for their dinner.

–When the groundhog sees his shadow, there will be six more weeks of winter.

Fiction. No animal can predict long-range shifts in weather.

–Deer feed heavily before a storm.

Fact. Many mammals are sensitive to changes in air pressure and some can pick up low-frequency sound waves made by approaching storms, spurring them to fill their bellies before seeking shelter.

–Goose honk high, weather fair. Goose honk low, weather foul.

Fact. Geese choose altitudes where dense air provides lift for their wings. On sunny days, this may be thousands of feet up; it is closer to the ground when a low-pressure air mass moves in.

–Coming rain brings frogs out of the water and into song.

Fact. When air is dry, frogs rest low in the water; high humidity brings them onto land. Why they croak more-crows and ducks are also noisy on a falling barometer–nobody knows.

–Before the rain, bees stay close to the hive and ants march in a straight line.

Fact. Both probably pick up changes in atmospheric pressure and draw closer to cover.

–When the woolly bear’s brown band is wide, a bad winter abides.

Fiction. Animals can’t predict climate changes; they react only to prevailing atmospheric shifts.

–When the cicada falls silent, look to the sky for thunder.

Fact. Cicadas can’t vibrate their wings in high humidity, so they are quiet before rain. –K.M.