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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Tuesday, November 25th 2014
Created: Nov 25th 6:37 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
0 NO RATING Below Treeline / Below 1,000'
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Special Announcement

Good morning backcountry enthusiasts!  We've got a couple slight changes to the avalanche bulletin that we'd like to highlight:

First, we will be issuing danger ratings for three elevations bands this season- Alpine (above 2,500-3,000'), Treeline (1,500' to 2,500-3,000') and Below Treeline (Below 1,500'). These elevation numbers are not exact since treeline elevations vary across the region. This expansion will help forecasters, as well as the public to better describe and understand the differences in danger and avalanche concerns with respect to elevation.

Second, we have added a new table to the Mountain Weather section that will provide a quick snapshot of precip, temperature and winds at some key weather stations across our region.


The Bottom Line

The avalanche danger is LOW at and above treeline elevations today.  There still exists a possibility to trigger a wind slab in isolated terrain features, particularly in the higher elevations.  These wind slabs are variable in depth, and at the mid-elevations are resting on a slick rain crust. The continued lack of snow coverage results in no rating at our lower elevation band below about 1500’.  Another real hazard today deals with the potential for injury from collision with shallowly buried stumps, rocks and other hazards given the early season snowpack.

The next advisory will be Thursday morning (Thanksgiving Day!) at 7am. 
Outlook for Wednesday: 
With high pressure building into south-central Alaska today and through Wednesday, the weather and resulting avalanche conditions are expected to be very similar for tomorrow.


Primary Concern

Surface conditions appear to be shaping up in the Turnagain zone after last weeks onslaught of rain up to about 3,500’ that deposited a stout crust in what is now our mid snowpack.  Yesterday we found variable thickness wind slabs resting on this crust showing signs of good bonding.  This wind slab is capped off by 6-8” of new low-density snow that fell on Saturday and Sunday with very little associated wind.  Though no red flags were noted yesterday and stability tests did not produce any results, confidence in this forecast is low due to limited information and lack of travel into the upper elevations (above 3,000’) thus far.  Where we expect this mid-pack rain crust to finally disappear (~3,500’) wind slabs could be a bit touchier.  Approach these higher elevation alpine slopes with caution and evaluate the snow and terrain carefully before committing to a slope.

 

 

 

 

 

 

 

 

 

 

 

 

                     

 

                              An 'average' snowpit in the mid-elevation band.  Sunburst @ ~ 2,900 feet.


Secondary Concern

Glide cracks have been mostly covered up by this latest storm.  In this instance though, out of sight does not mean out of mind.  Keep a keen eye out for any new cracks opening up and steer clear of these dangerous features.  Conditions are ripe for new glide crack formation, particularly in the Turnagain area.  There is much to understand about this phenomenon but what is known is that these cracks can release very suddenly and without a real trigger.  Your best bet is to limit your exposure by steering clear of glide cracks.

An additional concern today and for the foreseeable  future involves the hazards associated with an early season snowpack.  Many rocks, stumps and previous glide cracks are thinly covered with this most recent storm.  Keep it conservative and in control, particularly in the lower elevations where snowpack is thinnest.  There is A LOT of winter to still be had and nobody likes being injured, especially early in the season!

 

 

 

 

 

 

 

 

 

 

 

 

Snowpack is thin at the lower elevations.  Expect to hike up to a half hour (Turnagain zone) before putting skis on.


Mountain Weather

Over the last 48-hours we’ve seen 6-8” of new low-density snow fall at the mid and upper elevations with just a dusting at the highway level (1,000’) through Turnagain pass.  Winds have been the big change over the last 2-days dropping off dramatically as we received this last bout of snow and averaging less than 10mph from the SE.  The rain/ snow line continue its march toward sea level with another ~1,200 -1,400 vertical feet to go.

Today we may see a few lingering flakes in the eastern Turnagain arm area with light winds (4-8mph) from the West.  Temperatures will continue a slight drop today and overnight with lows dipping into the mid-20’s at 1,000’.  This evening and into tomorrow we’ll usher in an upper ridge of high-pressure that should leave us under blue skies and light to moderate winds on Wednesday.


Below are the new weather tables for this season that give a brief snapshot of the past 24-hours for key weather stations in Turnagain Pass, Summit Lake and the Girdwood Valley.
Also, for a more in-depth look at our seasonal weather history click HERE.

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 31  0 19
Summit Lake (1400') 25   0 
Alyeska Mid (1539') 35   0 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 25  SE  14 
Seattle Ridge(2400')  28  variable 12 

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

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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