The Northwest Avalanche Center offers daily avalanche risk forecasts. Here’s what these hazard levels mean.
SEATTLE – The mountains of the Pacific Northwest have some of the heaviest amounts of snow in the country. The snow can create picturesque mountain scenes that call skiers and snowboarders into the mountains of Washington, but it is also a risk of avalanches.
Every fall and winter, the Northwest Avalanche Center (NWAC) provides daily avalanche forecasts for 10 zones in Washington and northern Oregon. The areas include the Olympics, Mount Hood, and eight different regions of the Washington Cascades.
The NWAC categorizes avalanche risks using a five-point avalanche danger scale. The ratings are determined by the probability, size and distribution of the avalanches. The ratings and meanings are listed below:
Low: Generally safe avalanche conditions. Watch out for unstable snow in isolated terrain features.
Moderate: Increased avalanche conditions for certain terrain features. Carefully assess snow and terrain and identify any features of concern.
Considerable: Dangerous avalanche conditions. Careful snow cover assessments, careful route finding and conservative decisions are essential.
High: Very dangerous avalanche conditions. Traveling in avalanche terrain is not recommended.
Extreme: Avoid any avalanche terrain.
There is also a “no rating” which means people “watch out for signs of unstable snow such as new avalanches, snow pops, audible collapses, and avoid driving on or under similar slopes”.
So how does the NWAC determine the avalanche risk for each zone during the winter months?
According to NWAC, field-based avalanche forecasters and meteorologists collect and analyze snow observations and analyze the weather forecast for each zone. Avalanche and snowpack information is gathered not only from NWAC forecasters and professional observers, but also from professionals, backcountry travelers and remote weather stations from across the region.
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The NWAC has one of the most comprehensive mountain weather data networks in the US, consisting of over 50 remote weather stations. The data collected by the outstations help the center provide real-time weather and snow cover information to the public.
The NWAC also works with ski slopes, national park and ranger rangers, and highway avalanche control programs to share information throughout the winter.
The NWAC publishes the daily avalanche forecast daily at 6 p.m. and works with the National Weather Service (NWS) to issue and distribute avalanche warnings, watches and other special bulletins.
According to the NWAC, avalanche warnings are issued if a “high” avalanche danger is expected for “many areas” within 24 hours, which can mean large geographical areas or “several aspects and / or elevations in a certain geographical area”.
An avalanche warning is issued whenever the danger is “high” or “extreme” in the three altitude ranges “below the tree line”, “near the tree line” and “above the tree line”.
The NWS shared the following warning signs of unstable snow and possible avalanches:
- You see an avalanche or see evidence of previous slides
- Cracks form in the snow around your feet or skis
- The floor feels hollow
- You will hear a “throbbing” noise as you walk, indicating that the snow is setting and a sheet of snow could come off.
- Heavy snow or rain in the past 24 hours
- Significant warming or rapidly rising temperatures
- You will see surface patterns on the snow that were created by the force of high winds. This could indicate that snow has been transported and deposited in dangerous drifts that may be released
In addition to providing mountain weather and avalanche forecasts, the NWAC’s mission is to raise avalanche awareness and reduce the impact on the population by providing information and data.
Traveling into the backcountry always involves a certain degree of risk, especially if you have no formal avalanche training or have not attended a course. The NWAC said the best way to get out of danger is to “avoid avalanche terrain altogether”.
The NWAC shared the following tips to avoid danger:
- Stay away from closed areas and do not cross ropes or closed gates in ski resorts or on highways
- Stop, regroup, and take breaks in non-avalanche areas, far from places where avalanches could come from above
- If you want to cross or drive up inclines with an incline of more than 30 degrees, only ever sit 1 person on the incline
- Keep your group in visual and voice contact
- Communicate clearly with your group about the location of the avalanche site, any safer terrain nearby, and a plan for travel and regrouping
- If necessary, use visual signals or two-way radios to communicate remotely
- If a partner loses a ski or their snowmobile gets stuck on a slope, don’t help them. Observe them from safer terrain below the slope
Download the KING 5 app to check the interactive radar in your area, as well as the latest forecast, cameras, and current conditions.
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