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Avalanche Forecast

Archived

Apr 20th, 2019–Apr 21st, 2019

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

Regions

Purcells.

Travel early, a warming snowpack will increase the chance for loose wet avalanches through the day. Lingering wind slabs may still be found in the high alpine.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

SATURDAY NIGHT: Clear, light north wind, alpine temperature -2 C, freezing level 1300 m.

SUNDAY: Mostly sunny, light southwest wind, alpine temperature +4 C, freezing level 2600 m.

MONDAY: Increasing clouds and isolated flurries up to 5cm, moderate southwest wind, alpine temperature +1 C, freezing level 2300 m.

TUESDAY: Flurries 5 cm, moderate and gusty southwest wind, alpine temperature 0 C, freezing level 2700 m.

Avalanche Summary

A natural loose wet avalanche cycle was observed on Thursday with the increasing freezing level.

On Friday, a natural wet slab avalanche cycle to size 3 was reported on all aspects from 2200-2700 in the western part of the forecast region. Toward the east, natural wet loose avalanches size 1.5-2.5 were seen on north-northeast aspects at 1900 m.

Snowpack Summary

The freezing level hovered around 2300 m to 2500 m during Friday's storm. Up to 15 cm of snow likely accumulated above the freezing level. The snow fell with strong southwest wind, forming wind slabs in lee terrain features. The snowpack is wet below treeline from recent rain and warm air.

Weak and sugary faceted grains may remain at the bottom of the snowpack in the alpine, producing a low likelihood but high consequence scenario. Steep, rocky areas with a shallow snowpack are the most likely places to trigger this layer. Below 1200 m the brown pow is showing, bike season is fast approaching.

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.

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.