Calculate Trouble

Time is of the essence in the backcountry. Learn how long it will take an impending thunderstorm or avalanche to find you.

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When close won’t cut it, use these trail-tested tips to hit the mark.

Thunderstorm distance: Count the seconds between flash and boom: 5 seconds means 1 mile. The danger zone is anywhere inside 6 miles, but rogue bolts can strike people as far as 10 miles away. Storms move quickly, so take evasive action early.

Avalanche threat: Continuously scan the terrain for telltale signs, especially on the lee side of peaks, below cornices, and on slopes angled 35 to 45 degrees. Look for horizontal fracture lines in the snowpack, listen for hollow or thumping sounds, and be aware of recent fluctuations in temperature, precipitation, and wind. Check with local rangers and survey forecasts at

Calculate trail mileage: No GPS? If you have a topo map, measure your route with a string. Or do some reckoning: The average hiker covers 2 miles an hour on level trails with no breaks. Deduct 25 percent if the trail is rough or steep.

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