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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Monday, April 11th 2016
Created: Apr 11th 4:18 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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
Special Announcement
  • This will the final week of daily avalanche advisories. Between Monday, April 18th and Saturday, April 30th we will be issuing advisories on weekends and intermittently during the week.

  • The Chugach National Forest has closed some riding areas to motorized use due to snow melting out. Please see the table at the bottom of this page for a complete list. Snug Harbor, Summit Lake and Turnagain Pass (N. of Granite creek) will remain open. 

The Bottom Line

Below 2500' the avalanche danger is CONSIDERABLE today due to a continued pattern of warm temperatures, rain and an active glide avalanche cycle. Natural wet loose avalanches in steep terrain are possible and human triggered wet loose avalanches are likely. Avoid being under the runout of glide cracks.

In the Alpine the avalanche danger is MODERATE. Human triggered wind slabs are possible on leeward slopes and cornices remain a hazard along ridgelines. If there are extended periods of sunshine today the danger may rise to CONSIDERABLE in the Alpine.

***Travel is not recommended in avalanche terrain on the West (motorized side of Turnagain Pass).

If you are headed to the Summit Lake area don't forget to check Summit Lake Summary 


Primary Concern

After driving through Turnagain Pass yesterday and observing the state of Seattle Ridge and the uptrack, travel in avalanche terrain (including runout zones) on the motorized (West Side) is not recommended. The snowpack below 2500' is saturated; there is natural wet loose activity and a very active glide avalanche cycle going on. Unfortunately there really isn't a way to negotiate a route to the ridge without being in danger. Seattle Ridge is literally falling apart. Essentially the hazard is HIGH on this side of the pass. Until we get a very hard freeze, the glide avalanche cycle completely ends or all the snow in the starting zones that threaten the uptrack avalanches, traveling here is like playing Russian Roulette. 

Glide avalanche hazard also exists on the non-motorized slide. Travel underneath existing glide cracks is not recommended. In addition, be on the lookout for new glide cracks forming. 


Secondary Concern

Natural wet loose avalanche activity was observed yesterday and may continue today. Overnight there has been a slight cooling trend with mid elevation temperatures dipping below freezing. This may cause a superficial freeze and thin crust. However if the sun comes out, more rain falls or the temperatures climb, human triggered wet loose avalanches will continue to be likely in steep terrain below 2500' and natural wet loose avalanches will be possible. 

If the snow feels punchy, unsupportable or slushy and you find yourself sinking in on your skis or snowmachine it is time to get off the slope. 

 


Additional Concern

In the Alpine new snow and wind have likely formed wind slabs on steep leeward slopes. Yesterday there was evidence of blowing snow and wind effect. The fresh wind slabs may be quite tender along ridgelines and on unsupported terrain. There is potential for a little more snow today and easterly winds. Look for cracking and remember warm temperatures and sun can make these slabs even more touchy. 

Cornices: This hazard continues to loom along ridgelines in the Alpine and may be triggered by the weight of a skier or a snowmachiner. These may also fall naturally with additional snow/wind loading or rapid warming. Remember these break farther back than expected and travel on or underneath should be avoided. 

Wind plumes on Sunburst yesterday. photo: Joe Kurtak


Mountain Weather

Yesterday was mostly cloudy to partly sunny with rain/snow showers and gusty easterly winds. Temperatures were in the mid 20Fs to mid 40Fs depending on elevation. 

Today will be mostly to partly cloudy with rain/snow showers and a possibility of sun. Temperatures will be in the mid 20Fs to low 40Fs. Winds will be easterly 10-25 mph. 

For Tuesday there looks to be a break in the showery weather with clearing skies as a ridge of high pressure moves over the region. There is another low moving into the Gulf that will most likely put us back into the moist pattern of scattered showers later in the week. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  35  0  0* 114 
Summit Lake (1400')  37  0  32
Alyeska Mid (1700')  34  .5  100

*Center Ridge maybe under reporting, data has been wonky for the past two weeks

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  26  ENE  18  51
Seattle Ridge(2400')  29  SE 20*   38

*Seattle Ridge did not record winds from 5 am-10 am yesterday.

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: Mar 25, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: Open
Skookum Drainage: OpenSkookum drainage closes to motorized use on April 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Primrose Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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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
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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