How Weather Affects Skiing
You should know what weather you are heading into so you'll be aware of the kinds of conditions you and your equipment may be up against. Often the knowledge of a possible storm may cause you to cancel a ski trip and seek other plans. Or maybe you are a person who enjoys skiing the backcountry in changing weather conditions, in which case the possibility of a storm makes you want even more to keep your plans. Here are some considerations to take into account.
Clear and quiet conditions are great for skiing. But if you are only a fair-weather skier you are missing a beautiful part of backcountry skiing. Understanding mountain weather allows you to take advantage of good conditions and avoid violent conditions. Always ask yourself, "If the weather does change, how will it affect me?" The best rule is this: Be prudent! Make camp or turn back before you are forced to. The good backcountry skier has a habit of constantly looking above and behind for weather changes and making mental notes on the route already skied.
Mountain Weather Changes Quickly
Each mountain has its own weather pattern that is associated with its shape and surroundings, causing air currents to lift, cool, and condense into clouds – this is called orographic lifting. Mountain valleys are warmer during periods of warm weather, but during the winter they become cold sinks holding super-chilled air at night. With the morning sun, air heats and rises up the mountain to create wind and storms on the peak tops. After sunset, air cools and once again descends into the valleys for the night.
Changes of Season and Storm Frequency
In the United States, storms occur more regularly during the middle of winter, from January up to and including March (roughly June, July, and August in southern latitudes). During winter, the sun is lower in the sky, with sunset occurring much earlier than in summer. Skiing normally occurs between about 8:00 AM and 3:00 PM during deep winter. It gets cold quickly as the sun drops in the sky. Spring rings fewer storms and longer days more suited for ski touring. For a seasonal overview of sunrise and sunset times and the length of days in the United States, consult the Farmer's Almanac and the internet.
Mountains close to oceans with coastal climates (Sierras, Alps, Cascades, and New Zealand Alps, for example) have higher humidity, and snowfalls of 3 feet (0.9 meters) are common. Mountains far inland from oceans have Continental climates (for example, Rockies and Wasatch) and have less humidity and snowfalls of 6 to 10 inches (15 to 25 centimeters) are more common, with occasional snowfalls over 2 feet (0.6 meters). Humidity is a natural junk maker as it keeps the snow settled with water, but this wetter snow stabilizes quickly with few avalanches (although it allows snow to stick to stepper slopes). Inland areas of the United States such as Colorado and Utah have dry, cold conditions perfect for dehydrated dry powder snow and powder avalanches.
New storms bring in new snow and powder skiing, but new snow can also impede progress by forcing you to break trail and thus increase energy expenditure and food demand. Waxing your skins with anti glop wax may be needed to accommodate new wet snow that is slowing your travel. Avalanche danger may increase, forcing you to reroute. Increased cold and wind demands more clothing. During deep winter ski tours, you will need more food, more stove fuel, and more clothing. With this in mind, snow camping could have been reserved for spring tours while hut tours are more ideal for the deep of winter.
Rain is the scourge of skiers. It can follow a recent snow when a warm, low-pressure system hits coastal mountains. Rain destroy the snow pack by cutting bonding layers between snow layers or between the whole snow pack and the ground. Skiing becomes difficult in rain because the snow is reduced to slush. Climbing skins can fall off due to moisture if they do not have a backup attachment system besides adhesive. The skiing is miserable and sloppy. Goggles fog up, making navigation difficult. It might be a good time to make camp or turn back.
Planning for Bad Weather
Have alternate routes planned in case of bad weather. It's good to have several high (haute) routes and low routes to choose from. Remember that the temperature normally drops 5 degrees Fahrenheit (-15 degrees Celsius) per 1,000 feet (305 meters) in elevation gained. Valleys may be sunny and comfortable, but you may still find blowing and snowing higher up. Higher routes are exposed to more weather and so they are better suited for periods of stable weather and low avalanche danger, like in the spring. Low routes are below the tree line, sheltered from the weather and avalanche activity. These two route design options let you ski the backcountry all winter long.
Getting the Complete Weather Picture!
You can get a good idea of what the weather will be doing by getting up to date weather forecasts before leaving home and by being observant in the field. An altimeter will back up your observations by detecting pressure changes in the atmosphere. At home there are several different sources of weather information. The internet and television are the primary sources of weather info these days. The satellite radar image shows where the big "storm cells" are. Ask yourself: How big is the storm mass? Does it have breaks and clearing areas? A mountain travel advisory with a winter storm warning that alerts motorists of blowing wind and poor visibility will also hold true for skiers. If you know where ski resorts are located and the snow amounts they are receiving, you can deduce the direction and speed of the storm. For long-term planning, a national weather bureau will have 5-, 10- and 30-day forecasts that are invaluable for multi day trips.