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Avalanche Forecast

Archived

Mar 8th, 2014–Mar 9th, 2014

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches possible, human triggered probable.
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, human triggered possible.

Regions

Sea To Sky.

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Tonight and Sunday: Heavy precipitation overnight (25-40 mm) drying out during the day. Expect a mix of sun and cloud Sunday. The freezing level should peak around 1600-1800 m, then drop to 1500 m. Winds are moderate to strong from the W-SW. Monday: Cloudy with sunny breaks and possible flurries. The freezing level is around 1200 m. Winds are light from the west. Tuesday: A mix of sun and cloud. The freezing level is around 1200 m and winds are light and variable.

Avalanche Summary

Several intentionally skier triggered slab avalanches up to size 1.5 were reported on Friday. These were within the recent storm snow. Expect the size and likelihood to have increased later on Saturday as snow accumulated. Natural slab avalanche activity should start to taper off on Sunday as conditions dry out; however, if the sun does poke out it could kick off a wet loose cycle on solar aspects and possible cause fresh cornice tabs to pop off.

Snowpack Summary

Another moist and mild storm was just starting to affect the region at the time of writing. It looks like this system could add another 30-60 cm of dense storm snow with very strong southerly winds. We could also see rain up to 1800 m near the coast. This adds to the previous 30-60 cm of rapidly settling storm snow late last week. Expect to find various storm snow instabilities and thin crusts within the recent snow. The early March melt-freeze crust is now down roughly 90-150 cm. This layer was found on all aspects at treeline and below, and on all but North aspects in the alpine. There are no new snowpack tests on this layer to report, but the continued loading and mild temperatures should help this weakness heal. The mid February crust/facet combo appears to be rounding and bonding in areas where it is buried 150 cm or deeper. In shallow snowpack areas, where the weak layer is buried less than 100 cm deep, it continues continue to fail with popping shears in snow profile tests. Big un-supported alpine North aspects are the most likely place to find (and potentially trigger) this well preserved weak layer.

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.

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.

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.