Trees, bushes or rocks that can help hold a slab in place.

The direction a slope faces.
ie: North, South, East, or West.

The surface on which an avalanche slides

When a snowpack collapses onto a buried weak layer. Also called whoomphing, this is an obvious sign of instability.

Natural avalanches possible. Human triggered avalanches PROBABLE.

An overhanging mass of snow created by the wind, usually near a sharp terrain break such as a ridge.

Large-grained, rounded crystals formed from repeated melting and freezing of the snow.

A steep gully in alpine terrain. In winter, a couloir is usually filled with snow bound by rocks on either side.

Wind blowing across a slope, depositing drifts on the sides of gullies or other terrain features.

The international standard ratings of avalanche danger: low, moderate, considerable, high and extreme.

Avalanches that break deeply into old weak layers of snow that formed some time ago.

Large-grained, faceted, cup-shaped crystals near the ground. Depth hoar forms because of large temperature gradients within the snowpack.

An avalanche that occurs in snow below freezing temperatures.

Widespread natural or human triggered avalanches CERTAIN.

Angular, larger-grained snow with poor bonding created from large temperature gradients within the snowpack.

When the entire snowpack slowly moves as a unit on the ground, similar to a glacier.

Heavely rimed new snow. Often shaped like little Styrofoam balls.

A slab avalanche composed of hard snow--usually deposited by strong winds or include old, hard layer of snow.

Natural and human triggered avalanches LIKELY.

When a snowmobiler ascends a slope to the highest point they can reach.

The downwind side of an obstacle such as a ridge.

The addition of weight on top of a snowpack, usually from wind drifting, new snow or rain.

An avalanche of loose snow-not a slab avalanche. Small loose snow avalanches are called sluffs.

Natural avalances very unlikely. Human triggered avalanches UNLIKELY.

Snow grains that have partially melted and then frozen again.

Natural avalanches unlikely. Human triggered avalanches POSSIBLE.

Weak layers that continue to produce avalanches several days or weeks after a storm or other rapid changes to the snowpack.

An avalanche of loose snow-not a slab avalanche. These avalanches start at a point and get wider as they move down the hill.

A metal rod used to probe through avalanche debris for buried victims.

The spreading of a fracture or crack within the snowpack.

A clear layer of ice formed from refrozen rain falling on the snow surface.

When a person triggers an avalanche some distance away.

An avalanche that occurs in an path that has avalanched previously in the season.

Supercooled water droplets that freeze to snowflakes in a cloud. Rimed snow often has a fuzzy appearence.

The zone where an avalanche looses speed and deposits debris at the bottom.

The angle, measured from horizontal, between the toe of the avalanche and the crown.

Wind eroded snow, which often looks rough as if it were sandblasted. Usually found on windward slopes.

The slow, deformation and densification of snow under the influence of gravity.

A relatively stronger layer of snow overlying a relatively weaker layer of snow. A slab avalanche is similar to a magazine sliding off an inclined table.

A small loose snow avalanche-not a slab. Also called point-release avalanche.

Same as avalanche.

Descend rapidly across an avalanche starting zone at about a 45-degree angle so that if an avalanche breaks, your momentum will carry you off the moving slab onto safe terrain.

Backcountry skiers and some snowboarders ascend slopes using climbing 'skins' attached to the bottom of their skis.

A slab avalanche of soft snow--usually just involving new snow.

When a slab avalanche slides a short distance and breaks down into deeper weak layers forming a stair-step pattern on the bed surface.

A thin, layer of ice formed by radiation from the sun. Not to be confused with melt-freeze crust or rain crust.

Frost that forms on the snow surface during calm, clear, humid conditions.

When one avalanche triggers another avalanche some distance away.

The change of temperature within the snowpack over a certain distance.

Terrain in which the consequences of an avalanche are especially hazardous, such as a gully, an abrupt transition, an avalanche path that terminates in trees, a crevasse field or a cliff.

A disturbance that initiates fracture within the weak layer causing an avalanche. In 90 percent of avalanche accidents, the victim or someone in the victim's party triggers the avalanche.

A place where a person triggers an avalanche.

New snow with relatively stronger snow on top of relatively weaker snow.

A relatively weaker layer of snow underlying a relatively stronger layer of snow.

A poor bond between two layers of snow.

An avalanche caused by snow loosing its strength after becoming damp, moist or saturated with water.

The upwind side of an obstacle such as a ridge. Usually snow is eroded from windward slopes making them relatively safer.

The added weight of wind drifted snow.

A slab of snow formed when wind deposits snow onto lee (or downwind) terrain. Wind slabs are often smooth and rounded and sometimes sound hollow.