Avalanche Forecast

South Rockies

Date issued

Mar 30, 2018 - 4:23 PM

Valid until

Mar 31, 2018 - 2:00 PM

Prepared by

mconlan

Expect to find wind slabs in exposed terrain features from recent snowfall with strong winds. Although a cool day is forecasted, assess snowpack warming on southerly aspects from the sun -- it could weaken the snow and trigger avalanches.

Regular season
Friday - March 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

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.

Saturday - March 31, 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 - April 1, 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

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.

Avalanche Problem 1: Wind Slabs

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

New snow and strong variable winds have produced wind slabs in exposed terrain features. Observe for signs of wind effect and slab properties before committing yourself into avalanche terrain.

Travel and Terrain Advice
  • Use caution in lee areas in the alpine and treeline where wind slabs are expected.
  • Observe for signs of instability, such as cracking, whumpfing, and avalanche activity.
  • Keep an eye out for localized areas of deeper snow accumulation, particularly on eastern slopes.

Avalanche Summary

On Thursday, large wind slab avalanches were noted on south to easterly aspects in alpine and treeline terrain, being triggered naturally and by snowmobiles.

On Wednesday, small to large (size 1 to 3) wind slabs were triggered naturally, generally on northerly to easterly aspects, and in alpine terrain.

Snowpack Summary

10 to 20 cm of new snow fell at higher elevations, with associated strong westerly switching to easterly winds. This new snow fell on previous wind slabs that exist on all aspects in exposed terrain.  In sheltered locations, expect to find dry snow in shady areas. A melt-freeze crust is found at low elevations, where the precipitation fell as rain.

About 50 cm deep, a crust is found up to 2200 metres.  At a similar depth, a layer of surface hoar is found on shaded aspects at treeline in parts of the region.

The midpack is well-settled and strong. This overlies sugary facets in thin snowpack areas.

Weather Forecast

SATURDAY: Mostly sunny, light southwesterly winds, alpine temperature -13 C, freezing level 700 m.

SUNDAY: Increasing clouds with light snowfall, accumulation 2 to 5 cm, light southwesterly winds, alpine temperature -10 C, freezing level 800 m.

MONDAY: Cloudy with morning snowfall, accumulation 10 cm, light easterly winds, alpine temperature -15 C, freezing level 700 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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