Avalanche Forecast

South Coast

Date issued

Mar 21, 2018 - 5:03 PM

Valid until

Mar 22, 2018 - 2:00 PM

Prepared by

ghelgeson

Watch for deteriorating avalanche conditions and steadily increasing hazard throughout the day. Both natural and human triggered avalanches will become increasing likely, especially at upper elevations where all the precipitation should fall as snow.

Regular season
Thursday - March 22, 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.

Friday - March 23, 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

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 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.

Avalanche Problem 1: Storm Slabs

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

New snow may not bond well to the old surface which is a mix of moist grains, crusts, surface hoar and facets. Natural and human triggered avalanches are anticipated at upper elevation as storm snow accumulates throughout the day.

Travel and Terrain Advice
  • Storm slabs are expected to most sensitive to triggering in wind exposed terrain.
  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Avalanche Summary

No significant avalanche activity has been reported recently.  New rain, snow and wind Wednesday night into Thursday will likely generate fresh avalanche activity that will be most pronounced in higher elevation terrain. 

Snowpack Summary

New snow and rain Thursday will fall on a mix of moist grains, crusts and potentially surface hoar/facets on high elevation polar (north and east) aspects.  The storms transition from warm to cold should be largely copacetic for our snowpack, but it does have potential to generate touchy storm slabs at upper elevations.

Last week's storm brought up to 15 cm of new snow to the alpine while rain saturated the upper snowpack at treeline and below. Surface conditions on solar aspects and below about 1500 m have been affected by daily melt-freeze cycles. In the limited alpine terrain where the recent precipitation fell as snow, stubborn old wind slabs may remain sensitive to human triggering.

Below any recent snow accumulations, the overall snowpack is well settled and strong.

Cornices loom over many ridge lines. Cornices become more unstable during the day as the temperature rises, especially when they are receiving direct sun.

Weather Forecast

A rather complex pattern is expected to deliver a significant shot of precipitation and wind with a warm to cold trend.  This storm should be most intense Thursday and begin to clear as we enter the weekend.  This is a great time to check out the Mountain Weather Forecast for further details! (Link below)

WEDNESDAY NIGHT: Freezing level around 1500 m, strong to extreme southerly wind, about 10 mm of precipitation.

THURSDAY: Overcast, freezing level starting at 1500 m, lowering to 600 m by sundown, moderate to strong southerly wind, 20 to 30 mm of precipitation expected.

FRIDAY: Broken cloud cover, freezing level holding around 700 m, light southerly wind, 4 to 6 mm of precipitation possible.

SATURDAY:  Scattered cloud cover, freezing level beginning around 600 m rising to 1000 m, light variable wind, no significant precipitation expected. 

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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