Avalanche Forecast

South Coast

Date issued

Mar 24, 2018 - 3:31 PM

Valid until

Mar 25, 2018 - 2:00 PM

Prepared by

jmcbride

It's still winter in the mountains. Watch for storm slabs that sit on crusts, surface hoar and/or facets at upper elevations. These slabs may be surprisingly deep on leeward slopes near ridge crests.

Regular season
Saturday - March 24, 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 25, 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.

Monday - March 26, 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: Storm Slabs

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

Thursday's storm came in with moderate southerly wind that has likely formed slabs on alpine lee features that may remain sensitive to human triggering. Periods of sun may also induce natural avalanche activity on solar aspects on Sunday.

Travel and Terrain Advice
  • Minimize exposure to sun exposed slopes if solar radiation becomes strong.
  • Watch for whumpfing, shooting cracks and recent avalanches which indicate unstable storm slabs.
  • Be cautious as you transition into wind affected terrain.

Avalanche Summary

Thursday morning ski cutting work on the North Shore mountains produced loose, dry storm snow releases (size 1) above 1000 m and loose, wet size 1 releases below 1000 m.

There have been no reports from the northern part of the region around Squamish, however it's likely that a natural avalanche cycle occurred in high alpine terrain with the recent storm.

Snowpack Summary

Around 45 mm of precipitation has fallen since Thursday. Rain transitioned to snow above 1000 m Thursday morning which produced about 25 cm of snow with light to moderate east/southeast wind. The warm to cold nature of the storm has allowed the new snow to bond well to the old surface up to treeline.

The alpine likely saw very little if any rain and more snow/wind. Up high the new snow is likely sitting on a mixture of weak grains including a crust on solar aspects and potentially facets/surface hoar on polar aspects.

Below the recent storm snow the snowpack is generally well settled and strong.

Weather Forecast

SUNDAY: Increasing cloud and flurries in the afternoon. Accumulation trace. Ridge wind light, southwest. Temperature at treeline near -3. Freezing level 800 m.

MONDAY: Cloudy, flurries. Accumulation 10-15 cm. Ridge wind light, southwest. Temperature at treeline near -2. Freezing level 1000 m.

TUESDAY: Cloudy, flurries or light rain. Precipitation 10 -15 mm. Ridge wind moderate, southwest. Temperature at treeline +2. Freezing level rising to 1600 m.

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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