Avalanche Forecast

Northwest Inland

Date issued

Mar 6, 2018 - 4:48 PM

Valid until

Mar 7, 2018 - 2:00 PM

Prepared by

jsmith

The sun can pack a punch this time of year. Be aware of signs of deteriorating stability such as snow pin-wheeling down slopes or small point-release avalanching below cliffs.

Regular season
Tuesday - March 6, 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.

Wednesday - March 7, 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.

Thursday - March 8, 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: Wind Slabs

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

Strong winds from a variety of directions over the weekend have redistributed snow into wind slabs on all aspects. Steep, convex, and rocky areas are the most likely spots to trigger these lingering wind slabs.

Travel and Terrain Advice
  • Watch for newly formed wind slabs as you transition into wind effected terrain.
  • Be aware of the potential for wide propagations due to the presence of hard windslabs.
  • Use ridges or ribs to avoid pockets of wind loaded snow.

Avalanche Summary

On Sunday, a few size 2 natural avalanches were reported on north and east aspects in the Howsons. A few large (up to size 3) cornices failed on east-facing slopes and triggered slabs on the very steep slopes below.

A MCR report from the Howsons (see here) reports widespread wind slab activity (size 1-2) during the peak of the storm last week and a decrease in activity by the weekend. A similar cycle of natural wind slab avalanches was also reported north of Hazelton. Although wind slab activity has declined, human-triggering remains possible.

Snowpack Summary

Moderate to strong outflow winds have redistributed 50-70 cm of recent storm snow in exposed areas. This storm snow has buried hard wind affected snow in exposed areas as well as sun crusts or dry facets in sheltered terrain.

A crust/surface hoar layer buried mid-January is now roughly 80-140 cm below the surface, and still has the potential to be triggered from a thin snowpack spot, or with a large trigger like a cornice fall.

It is unlikely, but may still be possible to trigger very large avalanches on facets at the bottom of the snowpack in steep, rocky, and shallow snowpack areas or with large triggers.

Weather Forecast

WEDNESDAY: Mix of sun and cloud / Light northwesterly ridgetop winds / Alpine high of -9

THURSDAY: Mostly sunny / Light southwesterly ridgetop winds / Alpine high of -9

FRIDAY: Mix of sun and cloud / Strong southwesterly ridgetop winds / Alpine high of -3

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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