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Avalanche Advisory

Turnagain Area Avalanche Advisory
Friday, April 17th 2015 5:20 am by Heather Thamm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

UPDATED Friday at 3:50pm:

TINCAN AVALANCHE: We just had a report of a very large skier triggered avalanche around noon today on both the North and South side of Tincan. We are currently gathering details; if anyone has any information please email wendy@chugachavalanche.org. At this time there are no known persons involved.

The slides were triggered remotely by a party of skiers on the CFR Ridge, below the top of Common Bowl. Both avalanches were reported to be 2-3' deep. The North slide may be over 1,500' wide and took out at least some of the Tincan Chutes area and further West along the ridge, running to the flats below. The South avalanche was in CFR bowl itself, under the corniced ridgeline. Todd's bowl did not avalanche.

Extreme caution is advised if you are thinking of heading out this afternoon. This includes avoiding avalanche terrain as well as runout zones from slopes above you.

 

The avalanche danger is MODERATE today both in the Alpine and at Treeline. Newly forming windslabs 4-8” thick could be tender on leeward terrain features. Should a large low-pressure system arrive earlier than expected the avalanche danger could become CONSIDERABLE by early evening. Wet loose avalanches will be possible at lower elevations should surface conditions become saturated due to warming day time temperatures and rain.  Evaluate snow and terrain carefully and pay close attention to changing snow conditions throughout the day. 


 Show the Complete North American Avalanche Danger Scale
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'
Special Announcement

We are currently issuing advisories 5 days a week until our final advisory on Thursday, April 30th.  Advisories will be posted at 7 am each day except Mondays and Wednesdays.


Avalanche Problem 1

Today up to 5” of new snow combined with moderate winds (20-30mph) from the Northeast could form isolated wind slabs up to 8" thick on leeward terrain features.  On shaded features in the Alpine (where a surface crust doesn’t exist) these wind slabs could stress the most recent storm slab up to 2’ thick. At lower elevations these wind slabs will be forming on a surface crust and could be tender. 

Wind slab thickness will depend on how much snow falls today. A large low-pressure system is expected to push into our region this evening. Winds are likely to increase into the 40s mph and an additional 8” of snow is expected this evening. Should this storm arrive earlier then expected the avalanche danger could increase to CONSIDERABLE by early evening. 

Careful snowpack and terrain evaluation are required for every group traveling in the mountains. If you find that the snowfall intensity and strong winds are causing rapid loading, keep your slope angles below 35° and avoid large open slopes.

Deeper Persistent Layers:

There are several old weak layers burried deep within our snowpack. Today's moderate winds and new snow will likely make visibility challenging. Should a window apear making steeper more extreme terrain appealing, condsider that we don't have a lot of current info about these layers. It has been 6 days since activity has been observed in these deeper layers, but it is uncertain how much additional loading + the right trigger will re-awaken them.

 


Avalanche Problem 2

Springtime requires us to pay close attention to how the snow changes throughout the day. We have seen intense solar affect almost every day. This is a reminder that our current snowpack can change dramatically from the morning into the afternoon. Although sun isn’t supposed to be an issue today, it has suprised us over the last few weeks and subtle warming affects are playing more of a role than noticed.

As this storm moves into our area expect rain/snow line to start moving up in elevation and could be as high as 1500’ by Saturday morning. Should the lower elevation snow become wet and saturated wet loose avalanches will be possible. 

 

 

Turnagain Pass looks more like winter than it has most of the season. The Forest Service is closely monitoring the snow depths and snow density on the motorized side of the road for a potential motorized opening. There isn't quite enough coverage yet to protect the vegetation below, but check back here should this next storm come in cold.

 


Mountain Weather

Yesterday cloud cover in the morning was thick and in the afternoon skies became partly sunny at times. Scattered snow and rain showers were observed throughout the day with little to no accumulation. Temperatures were between 30-40F at lower elevations and averaged in the mid 20s F along ridgetops. Winds were calm in the morning increasing to 15-20 mph from the Northeast in the afternoon.

Overnight temps at lower elevations dipped just below freezing and only a trace of precipitation was recorded. Winds were moderate 15-25mph from the Northeast along ridgetops.

Showery rain and snow conditions are expected throughout today. Winds will increase in the afternoon as a large low-pressure system arrives tonight bringing rain and strong winds. Rain/snow line may be as high as 1500’ by Saturday.

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 34  75 
Summit Lake (1400') 34  12 
Alyeska Mid (1700') 34  .19  43 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 24  ENE  13  45 
Seattle Ridge(2400') 26  n/a  17  31 

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 06, 2018 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: ClosedClosed as of April 20th
Placer River: ClosedClosed as of April 17th
Skookum Drainage: ClosedClosed as of April 1st.
Turnagain Pass: ClosedClosed as of May 7th. Happy summer, see ya when the snow flies!
Twentymile: ClosedClosed as of April 13th
Seward District
Carter Lake: ClosedClosed as of 4/27
Lost Lake Trail: ClosedClosed as of April 13th
Primrose Trail: ClosedClosed as of April 13th
Resurrection Pass Trail: ClosedClosed as of April 20th
Snug Harbor: ClosedClosed as of 4/27
South Fork Snow River Corridor: ClosedClosed as of April 13th
Summit Lake: ClosedClosed as of April 20th

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