Date issued

Mar 10, 2018 - 8:01 AM

Valid until

Mar 11, 2018 - 9:00 AM

Prepared by

ian gale

We experienced a significant natural avalanche cycle yesterday. Expect the strong effects of the sun today to destabilize the snowpack again.

Regular season
Friday - March 9, 2018
Alpine

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation,cautious route-finding and conservative decision-making essential.

Natural avalanches possible;human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Below Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Saturday - March 10, 2018
Alpine

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Below Treeline

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Sunday - March 11, 2018
Alpine

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation,cautious route-finding and conservative decision-making essential.

Natural avalanches possible;human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Below Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Avalanche Problem 1: Wind Slabs

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

Strong south winds and recent storm snow have created wind slabs. Expect these slabs to be most reactive at ridgetop or in steep unsupported terrain. Today is forecast to be sunny and the strong solar radiation to make the windslab more reactive.

Travel and Terrain Advice
  • Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
  • Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Avalanche Problem 2: Persistent Slabs

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

Sun crusts are buried 30-60 cm on steep solar aspects. This interface provides a smooth bed surface and may contribute to larger than expected avalanches. It is possible for smaller avalanches to trigger this lingering problem.

Travel and Terrain Advice
  • If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
  • Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Avalanche Problem 3: Loose Wet

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

Today the new snow will get a blast of strong spring solar radiation. This should trigger a natural cycle of loose wet avalanches on solar aspects, most likely initiated from rock outcrops or dropping snow pillows.

Travel and Terrain Advice
  • Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.
  • Use extra caution on solar slopes or if the snow is moist or wet.

Avalanche Summary

Yesterday we experienced a significant natural avalanche cycle at Roger's Pass due to heavy snowfall and strong winds. Over 50 avalanches were observed, the largest were sz 3.5s and many ran to the full extent of their runouts. Expect another avalanche cycle again today with warm temps forecast and strong solar radiation.

Snowpack Summary

20cm of storm snow has fallen in the last 48hrs, this came in with strong, gusting extreme Southerly winds. Above freezing temps at valley bottom will have created a surface crust below ~1500m. A crust buried 60cm is present on steep solar aspects. Deep PWLs are dormant and buried over 1.5m. Cornices have seen new significant growth.

Weather Forecast

A strong upper ridge of high pressure is building over much of the province bringing sunny skies and warm temperatures. In our region we will see freezing levels at 1600m, an alpine high of -4 deg C and light ridge top wind. This warming trend will continue with freezing levels forecast to reach 2700m by mid week.

Danger Ratings Explained

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

Natural avalanches possible; human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

4 - High

Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

Natural avalanches likely; human-triggered avalanches very likely.

Large avalanches in many areas; or very large avalanches in specific areas.

5 - Extreme

Avoid all avalanche terrain.

Natural and human-triggered avalanches certain.

Large to very large avalanches in many areas.

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