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Avalanche Forecast

Archived

Apr 14th, 2017–Apr 15th, 2017

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

Regions

South Rockies.

Observations from the region have been very limited recently. If you are out in the mountains, please consider posting your observations to the Mountain Information Network and help us improve the bulletin. Click here for more details.

Confidence

Low - Due to the number of field observations

Weather Forecast

SATURDAY: Cloudy with sunny periods / Light to moderate west wind / Alpine temperature -5 / Freezing level 1500mSUNDAY: Mix of sun and cloud / Light south wind / Alpine temperature -4 / Freezing level 1600mSUNDAY: Mix of sun and cloud / Light southeast wind / Alpine temperature 1 / Freezing level 2300m

Avalanche Summary

Recent reports indicate several natural storm slab and cornice triggered avalanches to size 2 on all aspects tree line and above. Exposure to large overhanging cornices remains a significant concern. As the sun comes out over the weekend I would expect see cornices weaken and loose snow avalanches run from steep sun exposed slopes during the warmest parts of the day.

Snowpack Summary

Moist new snow falling last week above tree line has been redistributed by south and southeast winds. Cornices remain large and continue to become more overhanging. The middle of the snowpack is generally well settled and continues to transition into a spring melt/freeze regime. Expect the entire thickness of the snowpack to be moist or wet at lower elevations. At upper elevations, the bottom third of the snowpack is composed of weak facets, however there still is uncertainty to this layer's reactivity. That being said, a heavy load like a cornice fall or rapid warming of the snowpack could potentially trigger this layer.

Problems

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.

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.