Archived

Avalanche Forecast

Feb 5th, 2016–Feb 6th, 2016

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Regions: Glacier.

Avalanche danger will increase later today as a serious storm brings more snow, rising temps and lots of wind. Choose terrain carefully and minimize your exposure to the run-outs of avalanche paths when the storm hits.

Weather Forecast

A big system arrives today. Up to 10cm today, and another 20cm are expected overnight. Alpine temps are expected to rise to -2 but freezing levels will hopefully stay below ~1500m. Moderate SW winds, with strong gusts, will load lees. On Sat snow rates will taper off but moderate to strong W'ly winds will continue to load lees. Sun will be similar.

Snowpack Summary

Up to 40cm of light snow overlies settled snow from last weeks storm. In most areas the snow is loose and sluffs easily. Tests indicate that as it settles into a slab it may be triggerable. In some alpine areas wind slabs exist on lee features from S-SW winds. Jan 4th interface down 60-100cm and remains a concern in less traveled areas.

Avalanche Summary

Yesterday numerous size 2's and 1 size 3 occurred on steep N aspects, triggered by windloading, and ran into the fans. On Tues, size 2.5 avalanches occurred from S aspects at ~2300m. Wide crisp crowns up ~1m deep indicate that they likely failed on the Jan 4th. In addition, skiers could easily trigger the loose surface snow, sluffing fast.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Avalanche Problems

Storm Slabs

~40cm of light snow remains loose in many areas and sluffs easily. As the storm progresses, it is expected settle into a slab with added snow, mild temps and SW winds. Watch for signs like "upside-down" feeling snow or cracking that indicate a slab.

Ride slopes one at a time and spot your partners from safe locations.Be cautious of sluffing in steep terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Windslabs exist in some alpine areas, although they may now be hidden by the new snow. Be curious if you are venturing into the alpine; use your pole to probe into the snow and feel for windslabs and look for clues of wind-loading like drifts.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Use caution in lee areas. Recent wind loading have created wind slabs.

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Persistent Slabs

The Jan 4th layer is a lingering concern, and it is a tricky one to assess. Where it exists it is down 80-120cm, but it is not evenly distributed & is sporadically reactive. It has been triggered recently by cornices, resulting in large avalanches.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.Be cautious on convex rolls at and below treeline where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 3