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Don’t Want to Hike in the Rain? Be Your Own Weather Forecaster

Labor Day has passed—but it’s still hiking season even if you have to be more careful now to avoid the rain. Michael Fagin, owner and lead forecaster for Washington Online Weather, will turn you into your own weather forecaster.

An avid hiker living in the notoriously wet Puget Sound region of Washington State, Fagin is always looking for the sunny side of the trail. The following weather forecasting tips are drawn from Fagin’s new book (co-authored with Skip Card), Best Rain Shadow Hikes: Western Washington (The Mountaineers Books, $16.95 paperback).

Most forecasters who watch the sky practice the art of cloud watching, says Fagin. Clouds change in a distinct progression as a warm front approaches; each change can indicate incoming weather.

Using your altimeter. Since most of these devices rely on changes in barometric pressure to calculate elevation, they can also be used to forecast weather. For example, hikers who maintain a fixed position but see their altitude rising can tell that the surrounding air pressure is dropping, an indication of a low-pressure system and the possible arrival of a warm wet front. (The rule of thumb is to monitor the altimeter every three hours. If altitude rises 80 feet every three hours, a low-pressure is probably on the way)

Cirrus clouds. These thin, fibrous clouds hover above 16,500 feet and consist of ice crystals. These clouds can act as a miniature prisms and split sunlight into its component colors, creating a halo effect. These wispy clouds do not produce precipitation. However, cirrus clouds that cover the entire sky can predict a different weather pattern. The clouds with the hooks are nicknamed “mare’s tails” and usually indicate strong winds in the jet stream. All signs are beginning to indicate an impending weather disturbance.

Jet plane trails. If you see a jet plane that has left in its path a lingering trail of condensation that stretches across the sky, instead of contrails that are small and quickly fade, this means that more moisture is in the air, another sign that a warm front is advancing.

Lenticular clouds. A large, mushroom-shaped cloud cap covering the summit of Mt Rainier—a lenticular cloud— indicates strong winds in the upper atmosphere and high-level moisture, two ingredients that often signal the arrival of a warm front. The combination of falling barometric pressure and a lenticular cloud that follows the previous cloud patterns will bring rain to the region 90 percent of the time. Lenticular clouds can occur atop all major volcanoes in the state, as well as nonvolcanic mountain barriers such as Mount Stuart. The clouds can sometimes be stacked vertically. At other times, winds can blow them away from a mountain peak and spread a dozen or more across the nearby sky.

Altostratus clouds. These sheetlike clouds are made up of water droplets, unlike the wispy cirrus clouds that consist of ice crystals. They sometimes produce a brief shower.

Adapted from Best Rain Shadow Hikes: Western Washington by Michael Fagin and Skip Card, The Mountaineers Books, $16.95 (paperback).

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