Sat, April 23, 2016 Turnagain Pass Avalanche Forecast

Sat, April 23rd, 2016

Alpine

Above 2,500'

1 - Low

Treeline

1,000'-2,500'

3 - Considerable

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

Glide Avalanches

Glide Avalanches

Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.

More info at Avalanche.org

As mentioned in the advisories earlier this week, the glides have “migrated” across the road. Magnum and Cornbiscuit both had glide avalanches occur in West facing terrain in the last few days. New cracks continue to appear and existing cracks keep growing. With new glide avalanches being observed daily the travel advice remains the same… Avoid being under the runout of glide cracks. The small glide crack near the common skin track on Sunburst has grown and is above a terrain trap.

Magnum and Cornbiscuit

Sunburst glide crack

Avalanche Problem 2

Wet Loose

Wet Loose

Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

More info at Avalanche.org

The rain/snow line today is forecasted to be 4100′. The precipitation amounts should be minimal but the overall wetting of the snowpack will rise in elevation with the warm temperatures. There was little to no freeze last night. 2-5″ of snow fell on Tuesday above 2000′ (more in the Girdwood Valley). Below 1800′ the snowpack is saturated and barely supportable. All these ingredients combine for wet loose avalanche potential today. Below 2500′ triggering a wet loose avalanche is likely in very steep terrain. In the Alpine wet loose avalanches in the new snow may also be a consideration as the newer snow gets more and more saturated. Pay attention to how much snow is getting pushed while making a turn and watch for moving snow that may entrain surface snow as it gets moving.

Additional Concern

Normal Caution

Normal Caution

Normal Caution means triggering an avalanche is unlikely but not impossible.

More info at Avalanche.org

At elevations above approximately 2,500′ (in the Alpine) the snowpack is generally stable. Watch for unstable snow on isolated terrain features.

– Lingering wind slabs

– Wet loose avalanches

– Cornice falls

Weather

Sat, April 23rd, 2016

Yesterday was overcast and there were rain showers throughout the day. Temperatures were in the low 40Fs at 1000′ and the low-mid 30Fs at 3000′. Winds were moderate and easterly.

Today will be mostly cloudy with rain showers forecasted throughout the day. Temperatures are expected to climb into the 40Fs at 3000′. Easterly winds will be 10-25 mph.

Temperatures may cool a bit overnight but Sunday looks to be very similar to today. The overall pattern of cloudy skies and rain showers remains in place for the week to come.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	39	0	0	106
Summit Lake (1400′)	41	0	0	20
Alyeska Mid (1700′)	37	0	.15	90

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	31	ENE	20	41
Seattle Ridge (2400′)	33	SE	15	33

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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