What's Behind an Avalanche Warning?

news image
Special Stories
23 Jan 2018 7:32 PM
Parts of the Cascade Mountains in Washington state were under avalanche warnings Tuesday as our latest winter storm moved into the Pacific Northwest. The warnings were due to heavy snow and high wind. https://twitter.com/NWSSeattle/status/955681415407923201 Avalanche Simply put, an avalanche is a rapid flow of snow sliding down a slope. Avalanches typically grow as they tear down slopes entraining more snow and at times trees, rocks, and other debris. They can be triggered by anything from gravity, to wind, to humans or animals, or even a change in temperature– just to name a few. The one constant between each of these events is that avalanches are never random, and no matter the type there are always precursors to a slide. In each slide, initiation occurs when the load exceeds the strength of the snow. The load is simply the weight of the snow, but the strength depends on everything from type of snow to the different layers of snow and even the steepness of the hill. And that just scratches the surface. https://media.weathernationtv.com/news/avalanche-danger-unstable-snowpack/ Wind Load The avalanche warnings for the Northwest were for heavy snow and high winds. This is known as a wind load. As strong winds blow new snow falling from the sky, it can do a few different things to cause an unstable snowpack.
  • Wind can cause snow to pile up in certain areas almost 10 times faster than it otherwise would just falling from the sky.
  • As snow blows in the wind the flakes erode and change shape, making for a much more dense and therefore heavier snowpack.
  • Strong wind can deposit snow on the leeside of a mountain, piling it up to the point of instability. Often in the form of a large cornice.
  • Wind can also erode snow from the windward side of the mountain, eating away at the essential portion of the snowpack for stability.
Avalanches and You The good news is that more than 90% of all avalanches involving a person, are caused by the person or people involved in the avalanche. This means that if you avoid the backcountry, you are safe. It is highly unlikely that a rogue avalanche will come down and sweep away your romantic mountain-side lodge. But if you plan on heading into the backcountry. Be safe. Know the dangers. And always check your local avalanche forecast center. https://www.facebook.com/WeatherNation/videos/10155053412479874/ For WeatherNation — Meteorologist Jeremy LaGoo 
All Weather News
More
Summertime Heat Prompts Fire Danger in the Northern Plains

Summertime Heat Prompts Fire Danger in the Northern Plains

NORTHERN PLAINS - Temperatures were incredibl

12 May 2025 10:40 PM
Florida’s Rainy Season Starting Ahead of Schedule

Florida’s Rainy Season Starting Ahead of Schedule

An upper-level low will meander around the Gu

12 May 2025 10:35 PM
Severe Threat Continues in the Southeast

Severe Threat Continues in the Southeast

The Southeast can not seem to shake the storm

12 May 2025 10:30 PM
Severe Weather Ramps Up Late Week

Severe Weather Ramps Up Late Week

We've been stuck in a pretty stagnant pattern

12 May 2025 7:55 PM
Northern Great Plains and Rockies Storm Threat

Northern Great Plains and Rockies Storm Threat

HIGH PLAINS - With temperatures pushing 80-90

12 May 2025 7:45 PM
Flood Threat Lingers in New England Saturday

Flood Threat Lingers in New England Saturday

A break in storms for the Northeast is on the

10 May 2025 7:25 PM
Huge Hail in the Mid-South Thursday, Storms Linger in the Carolinas Today

Huge Hail in the Mid-South Thursday, Storms Linger in the Carolinas Today

Hail over the size of tennis balls and baseba

9 May 2025 7:45 PM