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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Kevin Wright  
Saturday, February 23rd 2013
Created: Feb 23rd 6:08 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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Special Announcement

The Chugach National Forest is looking for your comments in the Forest Plan Revision Process.  Public meetings are being held this week and next in Seward, Soldotna, Anchorage, Cooper Landing, Moose Pass Cordova and Valdez.  Forest Managers and decision makers are anxious to hear input from the people who live, recreate and make a livlihood on the Chugach National Forest.  For more information and meeting dates click here.


The Bottom Line

Today's avalanche forecast is largely based on the weather forecast.  A blizzard warning is in effect, meaning severe winter weather is expected or occuring.  The danger rating will start out as MODERATE above treeline this morning, and transition to CONSIDERABLE if storm snow builds to the 10 inches that may accumulate by this afternoon.  

Avalanches today will be low volume and shallow in depth, but will be found in many areas.  The main concern to backcountry travelers won't develop until later today.


Primary Concern

Building storm snow, combined with wind today will add a new slab on top of an already loose and weak surface.  We can expect tender soft slabs from wind buildup today to travel far and fast, but initially low volume.  We have a couple questions to answer while in the backcountry today.

1.  How much snow is building from today's storm?

2.  How is the new snow bonding to the old snow?

If the answer is "lots of new snow" and "poor bonding", then the danger rating will be bumping into CONSIDERABLE by the afternoon today. 

Yesterday we saw medium size natural and skier triggered sluffs, with a few small slabs from wind (see picture below from Pete's South).  With new snow expected today, we can expect a similar avalanche character but on a larger scale.  Loose snow sluffs are likely, and soft wind slabs 1-2 feet deep are possible by this afternoon.


Secondary Concern

I was almost ready to drop the discussion about persistent weak layers, then Wendy and Sean found a great example of this problem lingering in Turnagain Pass yesterday.  We still consider this problem to be isolated, but the red flags and pit results indicate that those isolated areas may still be triggerable by a person.  This problem is from the late January crust that produced a weak layer between 1900 and 3000 feet and has been responsible for a handful of human triggered avalanches.   Be aware of this problem at mid-elevations and especially in areas with a thinner snowpack where the weight of a person could collapse the problem weak layer.


Mountain Weather

Yesterday was sunny, with a little wind up high.  The sun from the last 2 days has just barely added a crust to direct south facing aspects, thin enough that it's not a big issue for skiing quality.  Wind had enough force to build and trigger some very shallow slabs in steep terrain. 

Today, a blizzard warning is in effect until 4pm.  5-10 inches of snow are predicted for the mountains of Turnagain Arm, with east wind 35-45mph.  Temperatures should remain cold enough for snow to sea level.  The front responsible for today's blizzard will pass by this evening, but snow showers remain in the forecast for tonight and the next several days.


Wendy will issue the next advisory tomorrow morning, February 24th.

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: Nov 18, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedOnly a few inches of snow sits at the motorized lot, not enough to open for snowmachining at this time. Updated Nov. 18, 2017
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail is expected to 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
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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