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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Wednesday, March 23rd 2016
Created: Mar 23rd 4:25 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
0 NO RATING Below Treeline / Below 1,000'
 Show the Complete North American Avalanche Danger Scale
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The Bottom Line

The avalanche danger is CONSIDERABLE above 1,000’ today.  Human triggered wet loose and wet slab avalanches in steep terrain (greater than 35 degrees) will be likely and large enough to be dangerous as the moist surface snow extends up to ridgetops in many locations around Turnagain Pass. Natural wet avalanches will be possible.  Cautious terrain evaluation is essential today.

In addition, it will be possible to trigger a tender wind slab and/or cornice fall in the Alpine. In the mid-elevation band, the already active glide avalanche cycle seems to be ramping up. New glide cracks are appearing, growing and releasing very large avalanches in the past two days. Avoid travel underneath glide cracks.


Primary Concern

For the third night in a row temperatures stayed above freezing in the low to mid elevations and over 1.5" of rain fell on the snowpack in the last 24 hrs up to 2000' or higher at Turnagain Pass. Natural wet loose avalanches were observed yesterday and were large enough to injure or bury a person. Triggering a wet loose or a wet slab avalanche in this saturated snow will be likely today and may be occurring naturally as well. Wet avalanches once initiated can entrain more snow rapidly and are very hard to get out of. They can be particularly hazardous if they push you into a terrain trap and bury you deeply. Stick to low angle terrain and avoid runout zones where avalanches from above may catch you. Warm temperatures and rain showers are forecasted to continue today. There may also be some sunshine that could exacerbate the wet snow issues. Ski and snowmachine conditions will not be pleasant.

 

Turnagain Pass weather at 2:30 pm yesterday.


Secondary Concern

We have been talking about glide cracks and glide avalanches for months and the past couple weeks have been notably active. The past couple days maybe even more so as the snowpack gets wetter and more slurpy like. New cracks are appearing and releasing as very large glide avalanches. The idea of someone getting caught in one of these is pretty terrifying. Navigating through the mid-elevation band is getting more and more complex. There is a glide crack that is opening directly above the Seattle Ridge up-track. I couldn't get a good picture of it yesterday but I don't want to be parked or stuck under that and traveling under a glide crack is a total dice roll. The only way to mange this hazard is avoidance. 

 

Glide avalanche above the Bertha Creek parking lot.

 Debris pile from the avalanche above.

 Whiteline avalanche path glide crack to glide avalanche progression over 3 days. Images from 3.20, 3.21 and 3.22. Photos: Tim Glassett


Additional Concern

Wind slabs and Cornices:

Yesterday in the Alpine the precipitation was falling as snow and there were sustained easterly winds in the 20-30s with gusts into the 50s. This may have created tender wind slabs in ridgeline starting zones and added weight to already very large cornices. The wind slabs will be found in steep leeward terrain. Watch for cracking in wind-loaded areas and avoid travel on or under cornices. Warm temperatures can make cornices more likely to fail. 


Mountain Weather


Yesterday was overcast with broken clouds and rain/snow showers on and off throughout the day. Temperatures were above freezing at lower elevations and in the high 20Fs at 3000' and stayed warm overnight. Winds were easterly, 20-30 mph with gusts into the 50s. 

Today will be partly to mostly cloudy with isolated showers and light winds. Temperatures are forecasted to be in the 40Fs at 1000' and the mid to high 30Fs at 3000'.

Tomorrow may see a bit of clearing however the unsettled pattern with cloudy skies and showers persists throughout the week with more moisture on tap for the weekend. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 36   rain 1.7  129 
Summit Lake (1400') 37   drizzle .1   43
Alyeska Mid (1700')  35 rain  1.1   107

 

RIDGETOP 24-hour data (6am - 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 28  ENE  27  52 
Seattle Ridge(2400') 30  SE   25 52 

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).

Winter snowmachine use open/closed status and riding conditions updates

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: May 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

Subscribe to the Turnagain Area Avalanche Advisory:

The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
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