Dashboard Regions Weather Stations Radar Alerts Glossary
Contact About
Log In

Register for an account and never miss a forecast again!

Register

Avalanche Forecast

Archived

Mar 29th, 2021–Mar 30th, 2021

Alpine
Natural avalanches unlikely, human triggered possible.
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, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

South Coast.

Storm slabs at higher elevations may be reactive on Tuesday, especially in wind-loaded areas. 

The spring sun packs a punch and can quickly initiate natural avalanche activity and weaken cornices. Back off slopes if you see natural avalanches, snowballing and moist snow surfaces.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

A ridge of high pressure will dominate for the next couple of days bringing cooler and dryer conditions.

Tuesday: Mix of sun and cloud. Ridgetop wind light from the northwest. Alpine temperatures near -2 and freezing levels 700 m.

Wednesday: Mix of sun and cloud. Ridgetop wind moderate from the southwest. Alpine temperatures near +7 and freezing levels 2300 m. 

Thursday: Cloudy with light precipitation amounts. Ridgetop wind moderate from the southwest. Alpine temperatures near +6 and freezing levels 2100 m. 

Avalanche Summary

On Sunday, a recent MIN report showed the new 10 cm of storm snow was easily running on a firm crust below 1200 m. The recent storm snow may start to settle and bond by Tuesday. However, wind-loaded slopes at upper elevations may take longer. Wind slabs may be reactive to human triggers. 

Solar facing slopes could destabilize rapidly when the sun is on them and initiate natural wet loose avalanches. Cornices are large and could also deteriorate under the warm spring sun. They require a large berth from above and below.

Snowpack Summary

A mix of rain and snow brought 30-50 cm/mm of precipitation to the region since the weekend, accompanied by moderate to strong southerly winds. This precipitation fell on about 30-50 cm of older snow that fell last week. The average snowpack depth at treeline elevations is 350 cm. 

A solid melt-freeze crust exists at lower elevations that previously saw rain. 

Along ridgelines, cornices are large and may weaken when the sun comes out. 

Terrain and Travel

  • Brief periods of sun could quickly initiate natural avalanche activity.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Be aware of highly variable recent wind loading patterns.
  • Back off slopes as the surface becomes moist or wet with rising temperatures.
  • Cornices become weak with daytime heating or solar exposure.

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.