Date issued

Jan 29, 2018 - 8:09 AM

Valid until

Jan 30, 2018 - 8:00 AM

Prepared by

ian gale

With heavy snowfall and warming temps today expect a reactive storm slab and natural activity.

Naturals will run far, avoid overhead hazard and stay out of avalanche runouts!

Regular season
Sunday - January 28, 2018
Alpine

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.

Treeline

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.

Below Treeline

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.

Monday - January 29, 2018
Alpine

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.

Treeline

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.

Below Treeline

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.

Tuesday - January 30, 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

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.

Below Treeline

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.

Avalanche Problem 1: Storm Slabs

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

Heavy snowfall and warming temperatures will create a reactive storm slab. If triggered, the slab could step down to deeper weak layers. With steady snowfall accumulation in the last week expect to see avalanches gaining mass and running far.

Travel and Terrain Advice
  • Use conservative route selection, choose moderate angled and supported terrain with low consequence.
  • If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Avalanche Problem 2: Persistent Slabs

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

Persistent weak layers present a lower likelihood / high consequence scenario with the Jan 16th, 4th &Dec 15th surface hoar layers buried deep. These layers could be overloaded and reach their tipping point with today's warming and heavy snowfall

Travel and Terrain Advice
  • Be aware of the potential for wide propagations.
  • Use caution on open slopes and convex rolls at treeline where buried surface hoar may be preserved.

Avalanche Summary

There was a skier triggered a size 2 on Saturday, see Avalanche Canada Mountain Information Network (MIN) for more details. During the overnight period there was a natural cycle to size 3 with debris running well into runouts. With additional precip in the next 24 hrs, expect avalanches to continue to run full path in areas like Connaught Crk

Snowpack Summary

13cm in past 24hrs, 60cm of settling storm snow with 160cm of snow accumulation over the past two weeks. Expect to find pockets of wind slab along ridge lines and lee features due to the moderate south winds in the Alpine. The Jan 16 surface hoar is down ~60cm, Jan 4 down ~80cm and Dec 15 down ~1m+ making for a complex sandwich of weak layers.

Weather Forecast

The storm pattern continues and we will see heavy snowfall accumulations the next 36 hrs. Today will be overcast with 15-20cms of snow accumulation. Ridge wind will be 25-40 km/hr from the SW and freezing level will climb to 1700m. Tonight we could see another 20 cm of snowfall with wind gusts to 85 km/hr

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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