Avalanche Forecast

Archived

Mar 25th, 2025–Mar 26th, 2025

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural and human triggered avalanches likely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Lizard-Flathead, Flathead, Lizard.

Rising temperatures and strong sun are creating very dangerous avalanche conditions. Natural avalanches are likely. Avoid avalanche terrain.

Confidence

Moderate

Avalanche Summary

Numerous natural and artificially triggered size 1 to 2.5 storm slab avalanches were reported on Monday.

Looking forward, we can expect this activity to continue as temperatures continue to climb, with the possibility of deeper avalanches running on buried weak layers.

Snowpack Summary

The upper snowpack is heavy and moist or wet at all elevations.

Where still intact, a crust is buried 30 to 100 cm deep, except on high-elevation north and east-facing slopes.

A surface hoar or facet layer from late January is buried 100 to 180 cm deep on north and east aspects at treeline and above. Although it been observed to be improving, we won't rule it out as a failure plane as balmy temperatures warm and weaken the snowpack on Wednesday.

Weather Summary

Tuesday night

Clearing skies. 20 to 30 km/h southwest ridgetop winds. Treeline temperature +5 °C. Freezing level rising to 2700 m.

Wednesday

Sunny. 10 to 20 km/h south ridgetop winds. Treeline temperature +10 °C. Freezing level rising to 3000 m.

Thursday

Flurries bringing 1 to 5 cm of snow. 30 to 40 km/h southwest ridgetop winds. Treeline temperature +1 °C. Freezing level 2500 to 2300 m.

Friday

Flurries bringing 1 to 5 cm of snow. 10 to 20 km/h northwest ridgetop winds. Treeline temperature -1 °C. Freezing level 1000 to 2000 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid exposure to overhead avalanche terrain; avalanches may run surprisingly far.
Be aware of the potential for large avalanches due to buried weak layers.
Only the most simple non-avalanche terrain with no overhead hazard is appropriate at this time.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

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.

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.