Archived

Avalanche Forecast

Dec 16th, 2017–Dec 17th, 2017

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Coast.

Fresh storm slabs may bond poorly to chunky, variable crusts. If you see more than 30cm new snow on a firm crust, consider the danger to be HIGH.

Confidence

Low - Intensity of incoming weather systems is uncertain on Sunday

Weather Forecast

We're looking at significant precipitation totals from Saturday evening right through all of Sunday. Unfortunately it will get warm on Sunday afternoon. SUNDAY: Snow changing to rain by noon. Accumulation 15-20 cm snow / 20mm rain. Ridge wind moderate from the southwest. High temperatures near +2. Freezing level rising to 1800 m.MONDAY: Cloudy with sunny breaks and isolated flurries. Accumulation 5-10 cm possible. Ridge wind light from the west. Temperature near 0. Freezing level 800 m.TUESDAY: Flurries. Accumulation 10-15 cm. Ridge wind light from the southeast. Temperature near -1. Freezing level 700 m.

Avalanche Summary

No new avalanches have been observed during the past week; however, an avalanche cycle is expected on Sunday.

Snowpack Summary

A widespread melt-freeze crust exists on all aspects and elevations. How well the incoming new snow bonds to this crust will be a critical determinant of avalanche danger on Sunday.Below the snow surface, the upper snowpack is well-settled and bonding well to the late-November rain crust. Below tree line the snow pack is thin and there are many early season hazards. Snowpack depths range from 30 cm at 800 m elevation to 180 cm at 1220 m.

Avalanche Problems

Storm Slabs

Significant uncertainty exists for the forecast amounts of snow (or rain in the afternoon), and how well it may bond to the underlying crust. A conservative approach makes sense, especially if more than 20cm of new snow sits on a firm crust.

Choose conservative lines and watch for clues of instability.Avoid overhead exposure during periods of heavy loading from new snow, wind.Watch for signs of instability such as whumpfing, cracking or recent natural avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 3