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Avalanche Forecast

Archived

Apr 7th, 2016–Apr 8th, 2016

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

Regions

South Columbia.

Plan to start and finish your day early while the weather is very warm and sunny. Minimize your exposure to large sunny slopes and overhead hazard. 

Confidence

Moderate

Weather Forecast

FRIDAY: Mainly sunny. The freezing level remains close to 3500 m and winds could rise to moderate or strong from the W-SW late in the day. SATURDAY: A mix of sun and cloud. The freezing level could drop to 2000 m and winds are generally light from the NW. SUNDAY: A mix of sun and cloud. The freezing level shoots up again to 2500 m and winds are light and variable.

Avalanche Summary

I suspect sunshine and rapidly rising temperatures set off a widespread loose wet cycle on steep sun-exposed slopes on Thursday. Some areas may have seen cornices popping off and perhaps isolated slab avalanche activity. Friday will be a very similar day in terms of weather. We could see loose wet sluffing taper off a little, but the potential for persistent slabs and cornices falls could be even higher as the snowpack warms even more.

Snowpack Summary

Sunshine and soaring temperatures may have resulted in moist or wet snow on all aspects and elevations, except possibly very high true-north slopes. The existence and strength of a surface crust will be important on Friday. If a crust doesn't form or it breaks down really early, then avalanche danger might stay elevated for the entire day. A couple crusts could exist in the top 60-80 cm up to around 2000 m. We could see loose wet snow sliding on the upper crust with the potential for wet slabs running on deeper crusts. The late February persistent weak layer is down 80 to 120 cm below the surface. This layer may be a concern in isolated terrain, but it will probably take a large trigger like a cornice fall or surface avalanche in motion to set it off.

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.

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.