Avalanche forecast, watch, or warning: when to change plans and avoid avalanche terrain

Read the label before the map

Outlooks, weather forecasts, avalanche forecasts, watches, and warnings are not interchangeable

The National Weather Service supplies current conditions and weather forecasts to regional avalanche forecast centers, which assess the snowpack and issue avalanche forecasts. NWS pages and NOAA Weather Radio can also carry Avalanche Warnings and special advisories. The product name tells you which decision it can support.

Weather outlook

An earlier, broader signal that a weather pattern may bring snow, rain, wind, or warming. It helps with awareness, but it does not rate the stability of a specific snowpack or slope.

NWS weather forecast

The expected precipitation, wind, temperature, and timing for a place and period. Those inputs can load, drift, wet, or warm a snowpack, but the weather forecast alone is not an avalanche danger rating.

Local avalanche forecast

The snowpack-focused assessment. Read the issue time, valid area, elevation bands, slope aspects, avalanche problems, and travel advice. Conditions may be different above, below, or outside the forecast zone.

Avalanche Watch

Dangerous avalanche conditions are possible. Be prepared to adjust or cancel plans if a Warning is issued, and choose a low-angle alternative before travel begins.

Avalanche Warning

Dangerous avalanche conditions currently exist. Avoid avalanche terrain until conditions improve—including terrain below or connected to a slope that can release.

Terrain is part of the hazard

Ask whether you are on, below, or connected to a slope that can avalanche

NWS guidance describes three ingredients: a steep enough slope, an unstable snowpack, and a trigger. Avalanches generally occur on slopes steeper than 30 degrees, but a person does not have to stand on the steepest part to be exposed. A gentler bench can sit in a runout zone, and a low-angle approach can connect to a steeper slope above.

• Trace the entire slope above and beside the route, not just the ground directly under your feet.
• Identify gullies, creek beds, road cuts, bowls, and the bases of open slopes where moving snow can funnel or pile deeply.
• Treat a forecast boundary as a limit of the product, not a line where the snowpack suddenly becomes safe.
• Select the low-angle route and a turnaround point at home. It is easier to keep a conservative plan before the group has invested time and effort in reaching the mountain.
• Remember that equipment and experience do not stabilize snow. The best rescue is avoiding a burial.

The snow can tell you to leave

Recent slides, cracks, collapsing snow, loading, and warming are warning signs

A forecast is regional; observations are immediate. NWS lists several signs of unstable snow. Any one deserves attention, and several together are a strong reason to move away from avalanche terrain rather than trying to find a safer line through it.

Do not use the absence of obvious signs as proof of stability. Weak layers can be hidden, and another slope with the same aspect or elevation can behave differently. Combine what you observe with the current forecast and choose the more conservative option.

A decision sequence before leaving

Use the avalanche forecast first, then test the plan against weather, terrain, and change

1. Open the newest local avalanche forecast. Check its issue time, valid area, elevation and aspect detail, avalanche problems, and recommended travel behavior.
2. Open the NWS point forecast and active alerts.Look for new snow, rain on snow, strong wind, and rapid warming, plus any Winter Storm or Avalanche Watch or Warning.
3. Choose terrain that fits the message. If a Warning is in effect, avoid avalanche terrain. If a Watch or concerning forecast is posted, move to a conservative plan before the trip starts.
4. Prepare the group. Everyone in avalanche terrain needs appropriate education, practiced rescue skills, a working transceiver, a probe, and a shovel. Check each transceiver at the start; the gear is a last line of defense, not permission to take more risk.
5. Keep reassessing. Watch for recent avalanches, cracks, collapses, drifting, precipitation, and warming. Turn around when the evidence no longer matches the plan.
6. Keep an outside contact informed. Share the route, group, vehicle, and expected return time. Carry more than one way to receive information when cellular coverage is weak.

Match the message to the decision

A simple avalanche information ladder