Sat, March 28, 2015 Turnagain Pass Avalanche Forecast

Sat, March 28th, 2015

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

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

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

Moderate winds overnight that will continue today, combined with 5″ of new snow are enough to create pockets of fresh wind slab. Slab thickness will vary from 6-12″. Be on the lookout for recently formed slabs on the leeward side of ridges. General wind direction will be out of the East but remember that wind direction in the mountains is influenced by terrain. Snow that feels stiff, looks rounded or pillowy and produces shooting cracks should be avoided in steep terrain today.

Avalanche Problem 2

Dry Loose

Dry Loose

Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

More info at Avalanche.org

Natural and human triggered point release avalanches, also known as sluffs, will be possible on slopes over 40 degrees. Volume will be low to moderate but increase on sustained steep slopes and in the lower elevations. Sluffs will be dry above 2,000’ and gradually more damp with a decrease in elevation. Brief periods of sunshine will increase the likelihood of loose snow avalanche activity today.

Rollerballs and shallow wet loose avalanches observed on Magnum yesterday. More of the same can be expected in steep terrain today.

Magnum WL

Additional Concern

Cornice

Cornice

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

More info at Avalanche.org

Cornices have grown significantly over the last week. Steer clear of cornices and always know where the cornice begins and the underlying terrain ends. Pick routes on the way up that minimize time spent beneath these features.

Weather

Sat, March 28th, 2015

Over the past 24 hours temps have been mild. Snowfall and rain began overnight, with 5 €/.5 € of new (snow/H20) as of 6 am at the Center Ridge SNOTEL. The Girdwood Valley received 2 €/.2 €. Rain/snow line was around 500′. Ridgetop winds were out of the East averaging around 18 mph.

A broad area of low pressure to our South will spin and continue to pump light amounts of precipitation to the area today. Another 2-3 € of snow can be expected. Rain snow line will hover around the 1,800′ mark. Winds will be out of the East at 15-30 mph. Temperatures at 1,000′ will be in the mid 30s to low 40s F.

A continuation of unsettled weather will bring more of the same for the next several days. Warm Southerly flow associated with low pressure in the Gulf of Alaska will keep temps mild and precipitation coming in small doses.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	31	5	.5	63
Summit Lake (1400′)	33	trace	.1	11
Alyeska Mid (1700′)	34	2	.2	32

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	24	E	18	41
Seattle Ridge (2400′)	26	n/a	18	54

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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