Avalanche Advisory

Turnagain Area Avalanche Advisory Friday, December 20th 2013 6:16 am by John Fitzgerald ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.

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The general avalanche hazard is MODERATE today, with isolated areas of CONSIDERABLE hazard.  Steep wind loaded slopes in upper elevation starting zones will have the most reactive snow today.  It will be possible to find slabs up to 16” in depth in these areas.  In the lower elevations it will also be possible to find shallow pockets of reactive slabs that are sitting on weak snow.

Show the Complete North American Avalanche Danger Scale

North American Public Avalanche Danger Scale Avalanche danger is determined by the likelihood, size and distribution of avalanches. Danger Level Travel Advice Likelihood of Avalanches Avalanche Size and Distribution 5 Extreme Avoid all avalanche terrain. Natural and human- triggered avalanches certain. Large to very large avalanches in many 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. 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. 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. 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. Safe backcountry travel requires training and experience. You control your own risk by choosing where, when and how you travel.

2 Moderate Alpine / Above 2,500'

Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2 Moderate Treeline / 1,000'-2,500'

Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2 Moderate Below Treeline / Below 1,000'

Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Motorized access at Turnagain Pass and Johnson Pass open today.  Placer, Skookum, and Twentymile drainages remain closed.  Check the bottom of this page for the most up to date information on riding area openings and conditions.

Avalanche Problem 1

Wind and snow that came as a result of a quick hitting storm on 12/18 have left stiff wind slabs in upper elevation starting zones.  Winds from this recent storm deposited slabs on generally West, Southwest and South facing slopes.  These slabs are “upside down” where the wind was most prevalent and are sitting on weak snow on top of a crust.  It has been 24 hours since this last storm abated.  As a result the snow will be less reactive today.  That does not mean that things have “healed”.  Given the general makeup of our snowpack, it will still be possible to trigger old wind slabs that are not well bonded to the underlying snow.

If you experience collapsing like we did yesterday, it will be worth scaling back your objectives and terrain choices.  Collapsing is one of three obvious signs of instability (the others are recent avalanches and shooting cracks).  When any one of these signs are present it is the snow telling you to “back off”.  Avoiding steep slopes with snow that sounds hollow or has a rounded, pillowy look to it will help in avoiding this problem today. 

In the past 24 hours no new snow was reported.  Temperatures have risen overnight with increased cloud cover.  Ridge top temperatures are currently in the low 20s F.  Winds have been light out of the East and Southeast.

Today we can expect snow showers beginning in the morning and increasing late in the day into the overnight hours.  Accumulation of 1-2” is possible by the end of the day.  Temperatures will continue a general upward trend and should remain in the mid to upper 20s F at ridge tops.  Winds will be light out of the Southwest.

A trough of low pressure in the Bering Sea will continue to send small shots of moisture in our direction into the weekend.  Continued light snow showers and rising temps are on tap for the next several days.

This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Dec 18, 2018 )

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