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Avalanche Forecast

Archived

Apr 20th, 2014–Apr 21st, 2014

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

This bulletin was issued using very limited field data. Please send your observations to [email protected] out this video and blog post for more insight into managing spring conditions.

Confidence

Poor - Due to the number of field observations

Weather Forecast

Monday: A mix of sun and cloud becoming overcast in the afternoon with light flurries / Moderate southerly winds / Freezing level at about 2000mTuesday: Light to moderate wet snowfall at higher elevations / Moderate southerly winds / Freezing levels are uncertain, although some models are indicating up to 2500mWednesday: Mainly overcast skies with light flurries / Moderate southerly winds / Freezing level at about 1800m

Avalanche Summary

Fairly widespread loose wet avalanche activity was reported on Saturday. The avalanche activity occurred in response to solar radiation and warm temperatures.

Snowpack Summary

Note: We have very little recent data to base this summary on. If you're out in the mountains ask other locals about the current conditions and spend some time making snow and weather observations to help assess local hazard. Prior to the weekend the region received up to 40cm of new snow with the snow line hovering between 1500 and 1700 m. This recent snowfall overlies a melt-freeze crust in many areas. My best guess is that stubborn wind slabs exist in high, north facing terrain while warm temperatures and solar radiation have created moist surfaces everywhere else. If there is a good overnight freeze these surfaces will exist as a hard crust.The deep facet/crust persistent weakness buried at the beginning of February (now down up to 80-100+ cm) should stay on your radar, especially on all alpine slopes during sunny periods. Any activity at this interface would be large and destructive. Also, give large sagging cornices a wide berth when traveling on or below corniced ridges.

Problems

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.