Sat, January 04, 2014 Turnagain Pass Avalanche Forecast

Sat, January 4th, 2014

Alpine

Above 2,500'

3 - Considerable

Treeline

1,000'-2,500'

2 - Moderate

Below Treeline

Below 1,000'

2 - Moderate

0 - No Rating

1 - Low

2 - Moderate

3 - Considerable

4 - High

5 - Extreme


Travel Advice	Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.	Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.	Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential.	Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.	Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches	Natural and human-triggered avalanches unlikely.	Natural avalanches unlikely; human-triggered avalanches possible.	Natural avalanches possible; human-triggered avalanches likely.	Natural avalanches likely; human-triggered avalanches very likely.	Natural and human-triggered avalanches certain.
Avalanche Size and Distribution	Small avalanches in isolated areas or extreme terrain.	Small avalanches in specific areas; or large avalanches in isolated areas.	Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.	Large avalanches in many areas; or very large avalanches in specific areas.	Very large avalanches in many areas.

Avalanche Problem 1

Persistent Slabs

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

More info at Avalanche.org

A busy couple days in the backcountry brought a lot of avalanche activity through Turnagain Pass and Summit. On Thursday a group of skiers triggered at least 5 disconnected avalanches remotely from the ridge (See color picture below). Yesterday, a dog triggered an avalanche on the lower part of Tincan ridge (black and white photo below). Despite the search efforts of at least a dozen people, the dog was not found and is presumed dead. For reference, this is the same slide path that slid almost exactly a year ago.

Other reported avalanches include – Eddies, south and west aspects, Sunburst – SW aspect, Seattle ridge – Bowl 2. (Click on links to go to observations and more photos)

These avalanches are sliding on older and deeper weak layers. Once they get moving the entire depth of the snowpack can get stripped out. They are unmanageable in size, will trigger remotely, and can connect across large distances.

Terrain management is key to safe travel this weekend. This means stay off steep slopes and avoiding terrain traps and complex terrain.

Black and white photo – lower CFR, Tincan ridge. Crown at 2300 feet elevation

Upper Tincan ridge. Crowns near 3500 feet elevation.

Avalanche Problem 2

Storm Slabs

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

More info at Avalanche.org

New storm snow will exacerbate the persistent slab problem today as new stress gets added to the snowpack. By late today, the storm snow on its own may be deep enough to be its own distinct problem.

With over a foot of snow expected (possibly 2+ feet), we can expect natural avalanche activity to start late today and continue over night. We will likely reach HIGH avalanche danger during the peak of this storm.

Weather

Sat, January 4th, 2014

The last major storm was over the Dec 31st/Jan 1st holiday. Since then conditions have been mild and pleasant.

A big change is in the forecast today. A powerful storm is directing a moisture laden southern jet stream from warm lower latitudes straight at southcentral Alaska. The picture below describes the scenario far better than I could in words.

Snowfall is expected to start this morning and increase in intensity this afternoon and into the evening. Wind will be associated with this storm with a ridgetop wind from the East at 56-73mph. Rain at sea level is expected, transitioning to snow at 300-400 feet. Storm totals are predicted in the 16″-29″ range for the next 24 hours.

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
10/27/24	Turnagain	Observation: Tincan	Michael Kerst
10/21/24	Turnagain	Observation: Turnagain Pass Road Observation	Trevor Clayton
10/19/24	Turnagain	Observation: Tincan – Below Todds Run	Andy Moderow
10/18/24	Turnagain	Observation: Taylor Pass	Eli Neuffer
10/15/24	Turnagain	Observation: Tincan Common	John Sykes Forecaster
10/14/24	Turnagain	Avalanche: Tincan	CNFAC Staff
05/13/24	Turnagain	Observation: Eddie’s, Sunburst, Seattle, Cornbiscuit, Pete’s South	H Thamm
05/13/24	Turnagain	Observation: Turnagain Pass non-motorized side	Amy Holman
05/12/24	Turnagain	Observation: Warm up Bowl	Tony Naciuk
05/07/24	Turnagain	Observation: Turnagain Pass Wet Slabs	A S

Riding Areas

The riding areas page has moved. Please click here & update your bookmarks.