Avalanche Forecast

Issued: Jan 17th, 2020 4:00PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is high. Known problems include Storm Slabs.

Avalanche Canada cgarritty, Avalanche Canada

Rapid and continuous loading of new snow, strong wind, and rising temperatures are expected to bring a widespread natural avalanche cycle to the region this weekend. Travel in avalanche terrain is not recommended.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

Friday night: Cloudy with increasing snowfall bringing 15-20 cm of new snow by morning. Moderate southeast winds increasing to strong south by morning.

Saturday: Cloudy with continuing snowfall bringing 20-30 cm of new snow cm of new snow, continuing overnight. Strong south winds shifting southwest. Alpine high temperatures reaching -2 as freezing levels rise to 1300 metres by afternoon.

Sunday: Cloudy with continuing snowfall bringing a final 10 cm of new snow and 2-day snow totals to about 60 cm. Precipitation ending in light rain, with rain increasing again overnight. Moderate to strong south winds. Alpine temperatures reaching +1 as freezing levels rise to 1900 metres by afternoon and continue to rise overnight.

Monday: Cloudy with light rain, possible wet flurries in the alpine. Moderate south winds becoming light and shifting southeast. Alpine temperatures around 0 with freezing levels to 1700 metres.

Avalanche Summary

MIN reports from Wednesday on the North Shore described quite touchy conditions, with 5-15 cm-deep storm slabs triggering easily with skier traffic on steep slopes. Similar conditions are expected to have persisted through Thursday.

Looking forward, the coming storm is expected to form a widespread new storm slab problem as new snow accumulates and forms reactive slabs as a result of wind and rising temperatures.

Snowpack Summary

Up to 50 cm of new snow is expected to accumulate over the region by the end of the day on Saturday. This will bury wind-affected surfaces in exposed areas at all elevations and soft, low density snow in sheltered areas.

The new snow is expected to bring snow totals from the past week to about 170 cm. Collectively, all this snow rests on a hard melt hard melt-freeze crust below 1500 m and on previously wind-affected snow at higher elevations.

In some areas a weak layer of surface hoar exists above this crust. Recent snowpack tests on the North Shore have given variable, sometimes quite sudden results at this interface, particularly where this combination of crust and surface hoar was identified.

Terrain and Travel

  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
  • Avoid areas with overhead hazard.

Problems

Storm Slabs

An icon showing Storm Slabs

Heavy snowfall over Friday night and Saturday is expected to form a widespread new storm slab problem. Strong winds and rising temperatures will aid slab formation and promote natural avalanche activity.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely - Almost Certain

Expected Size

1 - 2

Valid until: Jan 18th, 2020 5:00PM