Avalanche Forecast

Archived

Mar 23rd, 2026–Mar 24th, 2026

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Below Threshold.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Below Threshold.

Regions

Haines Pass, Chilkat Pass.

Reactive wind slabs in combination with buried weak layers necessitate simple, low-angled terrain selection.

Confidence

Moderate

We are uncertain due to a limited number of field observations.

Avalanche Summary

A very large avalanche resulted in a fatality on March 22 on Mt McDonell. More information can be found here.

Snowpack Summary

Cornices are large and looming. Avoid travelling underneath them.

40 to 60 cm of recent snow and strong winds have formed storm slabs over a weak layer of crust/facets that have recently been reactive to human triggers.

There are multiple persistent weak layers of facets or crust/facets combinations in the top 200 cm of the snowpack. These layers are most likely to trigger in wind-affected areas or a shallow or thick-to-thin snowpack.

Weather Summary

Monday Night

Mostly clear skies. 10 km/h southeast ridgetop wind. Treeline temperature -12 °C.

Tuesday

Mostly sunny. 20 to 40 km/h northeast ridgetop wind. Treeline temperature -12 °C.

Wednesday

Mix of sun and clouds. 30 km/h northeast ridgetop wind. Treeline temperature -14 °C.

Thursday

Mix of sun and clouds. 20 km/h east ridgetop wind. Treeline temperature -16 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Use conservative route selection. Choose simple, low angle terrain with no overhead hazard.
Be aware of the potential for large avalanches due to buried weak layers.
Be especially cautious as you transition into wind-affected terrain.
Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.
Cornice failures could trigger large and destructive avalanches.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Cornices

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.