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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Tuesday, February 19th 2013
Created: Feb 19th 6:37 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.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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The Bottom Line

There is a MODERATE avalanche danger today for fresh wind slab avalanches above treeline. These will be building through the course of the day with an increase in easterly wind as the next system moves in. Steering clear of areas where the wind is visibly loading slopes will be your best bet for avoiding a fresh and sensitive slab - not to mention maximizing the good powder conditions. Additionally, loose snow avalanches will continue to be easy to initiate in the steeper terrain. Below treeline there is a LOW avalanche danger.


Primary Concern

For anyone stricken with Powder Fever – President’s Day was just what the doctor ordered. It was one of those great days to enjoy the backcountry. The only avalanche activity seen/reported in the Turnagain area was confined to loose snow sluffs and very small and manageable wind slabs. However, outside of the Turnagain area there was one significant avalanche in the Carter Lake region south of Summit Lake toward Seward. This is outside of our forecasting zone but in our neck of the woods nonetheless.  Alex Mclain, Summit Lake's CNFAIC forecaster, will try to get a closer look this afternoon.

Today, fresh wind slabs will be our main concern as the east winds ramp up. There is a plethora of loose snow out there to be blown into soft and sensitive slabs. These should be easy to identify by watching where the wind is blowing and visibly loading slopes. Cracking in the snow around you will likely be your next clue. Wind patterns get pretty complex around Turnagain but suspect areas are upper elevation ridgelines and over rollovers on south, west and northerly aspects.  

Loose snow avalanches in areas out of the wind will be an additional concern. With the decrease in temperature overnight, these could run further and faster than they did yesterday. This issue pertains to below treeline elevations as well.


Secondary Concern

There remain two layers buried below the surface we still have our minds on:

First, a thin layer of weak snow that sits on a late January crust. This is now buried 2-6’ deep and we have not seen avalanche activity within this layer in the Turnagain region. This has been more of an issue in the Girdwood Valley where avalanche activity has been seen and possibly in other surrounding locations (i.e., Placer Valley and 20-mile).

Second, the weak snow near the ground from our early season. This is the deep slab problem we have not been talking about much lately. It has gone dormant for now in the Turnagain and Girdwood areas, but we are concerned with the possibility of it coming back to life with a large multi-day storm cycle and/or in the spring. However, in shallower snow pack areas, such as Summit Lake, it is still more up front in our minds. It looks as though the Carter Lake avalanche mentioned above broke in the weak snow near the ground. Hopefully we will get more information on this today.


Mountain Weather

Once again our break between storms is short lived. Yesterday’s mostly clear skies, light northerly winds and temps in the teens are being replaced by another system headed this way. Winds have already shifted to the east overnight but are still light (~10mph).  These will pick up through the day into the 20-40mph range. Temperature is on rise at the ridgetops, going from the single digits to the mid-teens. An inversion has set in at the lower elevations where temps are hovering around 10F. Clouds may hold back enough for good visibility for the first part of the day but look to fill the skies by this afternoon.

Tonight and into tomorrow another quick hitting system will move through. It looks as though we will pick up another 6-12” with snow to sea level and strong east winds on the ridgelines. Stay tuned.

 


 

Kevin will issue the next advisory tomorrow morning, February 20th.

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

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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
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