Avalanche Forecast

Archived

Apr 25th, 2025–Apr 28th, 2025

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

Purcells, Dogtooth, East Purcell, West Purcell.

Start early, watch the crust closely, and end your day before it completely breaks down.

Don't forget about the deeply buried weak layers that may avalanche as the snowpack heats up.

Confidence

Low

Avalanche Summary

On Wednesday, there were a few small wet loose avalanches from slopes facing the sun.

Observations are very limited at this time of year.

Snowpack Summary

A thin, soft surface crust is likely to form overnight and break down each day. On northerly slopes in the alpine, there is 10 to 30 cm of preserved soft snow over settled old snow. Everywhere else there is a thick crust buried 10 to 20 cm deep.

Concern remains for the lower snowpack, which contains weak, sugary facets that may cause large avalanches if the upper snowpack loses strength during prolonged warm temperatures.

Weather Summary

Friday Night

Clear skies. 10 to 20 km/h southwest ridgetop wind. Treeline temperature 1 °C. Freezing level 2600 m.

Saturday

Mix of sun and cloud. 10 km/h northwest ridgetop wind. Treeline temperature 6 °C. Freezing level 2700 m.

Sunday

Mix of sun and cloud with 2 cm/mm of snow/rain. 10 to 15 km/h northwest ridgetop wind. Treeline temperature 4 °C. Freezing level 2600 m.

Monday

Mostly cloudy with 1 to 2 cm/mm of snow/rain. 20 to 30 km/h southwest ridgetop wind. Treeline temperature 3 °C. Freezing level 2400 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

The more the snowpack warms up and weakens, the more conservative your terrain selection should be.
Avoid steep, sun-exposed slopes when the air temperature is warm or when solar radiation is strong.
Avalanche danger will increase as the surface crust breaks down.
Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Problems

Wet Slabs

Wet Slab avalanches are the release of a cohesive layer of snow (a slab) that is generally moist or wet when the flow of liquid water weakens the bond between the slab and the surface below (snow or ground). They often occur during prolonged warming events and/or rain-on-snow events. Wet Slabs can be very unpredictable and destructive.

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.