Sat, January 03, 2015 Turnagain Pass Avalanche Forecast

Sat, January 3rd, 2015

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

1 - Low

Below Treeline

Below 1,000'

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

Dense slabs are spread across the forecast zone. These slabs are strong and can support a lot of weight. Underlying these slabs are a variety of weak layers. The most widespread of these layers is buried surface hoar, roughly 2’ down and found above 2,500’. We currently have a snowpack structure that shows some potential for slab avalanches.

On the plus side the strength of the slab in most areas is high, making it difficult to trigger an avalanche. Time and settling has allowed the buried weak layers to adjust to the slabs resting over them. While the likelihood of triggering an avalanche is on the low end of the scale, our tests continue to show us that propagation is still possible across slopes.

The best way to stay out of trouble today is to avoid suspected trigger points. These points are found on steep (>40 degree) rollovers and in areas where the snow is shallow. It is in these areas where it is easier for a person or group to impact the weak layer.

Avalanche Problem 2

Wind Slabs

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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

Dense wind slabs formed over the early part of this past week. These slabs (4-10″ thick) are generally well bonded to the surfaces below. However, it is worth keeping an eye out for the occasional pocket of stiff old wind slab, especially in very steep terrain. Jumping on steep rollovers on small test slopes is the best way to assess this avalanche concern. If venturing into more committing terrain, have an escape route in mind before moving over these slabs and be ready to ski or ride off of them.

With navigating around both of these avalanche concerns, continue to practice good travel habits. In steep terrain expose only one person at a time. Use islands of safety for re grouping. Have escape routes planned should an avalanche occur. Have a plan and communicate well within your group. Be mindful of and minimize exposure to groups below you.

Weather

Sat, January 3rd, 2015

Yesterday brought clear skies and more winter like temperatures to the area. Ridgetop winds were light out of the East/Northeast. Temps were in the teens to low 20s F. No new precipitation was recorded.

Today expect clouds and the occasional flurry this morning to give way to clear skies by the end of the day. Winds will be light out of the North at 5-10 mph. Temperatures will be on the decline, averaging in the 20s F at ridgetop level and dipping into the single digits F tonight.

High pressure will take hold over mainland Alaska for the next several days. This weather pattern will bring clear skies, cold temps and no precipitation.

PRECIPITATION 24-hour data (6am – 6am)

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	22	0	0	34
Summit Lake (1400′)	16	0	0	7
Alyeska Mid (1700′)	23	0	0	25

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	18	var	7	20
Seattle Ridge (2400′)	19	E	7	25

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

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