Avalanche Forecast

Issued: Jan 21st, 2020 4:00PM

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

Avalanche Canada shorton, Avalanche Canada

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Dangerous avalanche conditions exist on slopes that receive more than 25 cm of snow on Tuesday night.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

TUESDAY NIGHT: 15-40 cm of new snow, moderate wind from the southwest, treeline temperatures around -1 C.

WEDNESDAY: Cloudy with isolated flurries until a frontal system arrives in the evening bringing heavy rain and warming temperatures, moderate wind from the south, treeline temperatures around -1 C during the day.

THURSDAY: Heavy rain all day (50-70 mm), strong wind from the southwest, freezing level rises to 2000 m and treeline temperatures around +3 C.

FRIDAY: As the frontal system leaves the region freezing level lowers from 2000 to 1200 m meaning at some point rain will transition to snow (possible accumulations of 10-40 cm), moderate wind from the south, treeline temperatures around 0 C.

Avalanche Summary

Accumulations of new snow will likely create reactive storm slabs on Wednesday. Storm slabs could be extra reactive where they sit above hard crusts. Similar conditions existed on the weekend when a few small (size 1) human triggered slabs were reported (see this MIN report for an example).

Snowpack Summary

Between Tuesday morning and Wednesday morning 15-40 cm of new snow will accumulate. This snow is falling above wet and crusty snow left over from heavy rain a few days ago. Rain all the way to the top of the North Shore mountains ruined any remaining power from last week, but has also created a strong snowpack. The highest peaks of the region may still have dry snow and old wind slabs.

Terrain and Travel

  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • Be carefull around freshly wind loaded features.
  • Dial back your terrain choices if you are seeing more than 25cm of new snow.

Problems

Storm Slabs

An icon showing Storm Slabs

New storm slabs will form on Tuesday night as 15-40 cm of snow is expected to accumulate above wet and crusty interfaces. Be aware of steep slopes with deposits of new snow.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Jan 22nd, 2020 4:00PM