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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Friday, February 12th 2016
Created: Feb 12th 4:12 am
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.
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

Tomorrow Hatcher Pass Avalanche Center, Friends of the CNFAIC and Alaska Avalanche School are hosting a FREE companion rescue workshop from 10:30am-12:30pm at Hatcher Pass in the Gold Mint parking lot. Please join us! Click HERE for more information!


The Bottom Line

The avalanche danger is CONSIDERABLE for both wet avalanches and glide avalanches at elevations between 1,000' and 2,500'. This is due to rain-on-snow and warm temperatures that are weakening the snowpack in this mid-elevation band. Above 2,500', in the Alpine terrain, we also have a CONSIDERABLE avalanche danger, where human triggered wind slab avalanches are likely in steep leeward terrain and cornices will be tender.

Below Treeline  (-1000') a MODERATE danger exists where an avalanche in steep channeled terrain could run into this elevation band.

***Elevated caution is also advised in the Summit Lake area. Please see the Summit Lake Summary for more information and check out the observations page.


Primary Concern

Temperatures staying above freezing and rain falling to around 2200' have elevated the concern for glide avalanches. There are many glide cracks that haven't released, especially on Seattle Ridge, in terrain that threatens where people recreate. Today is a good day to stay away from these slopes and the runout zones. The large release on Eddies yesterday illustrates the magnitude of this hazard. New cracks may also appear and release without warning. This whole glide phenomenon is very unpredictable and the best advice is to steer clear! 

 

Glide avalanche on Eddies. This released sometime late 2/10-early 2/11.


Secondary Concern

An inch of water fell yesterday as rain to approximately 2200' (closer to 2" in Girdwood Valley). This began to saturate the settled storm snow and wet loose activity was observed.Temperatures at 1880' (Center Ridge) were above 32F for 24 hrs. Additional rain today will continue to add stress and decrease strength as it penetrates into the snow stitting on the 1/27 rain crust. Wet loose and wet slab avalanches are likely in the mid-elevation band (1000'-2500') in steep terrain.These may occur naturally or be triggered by the weight of skier or snowmachiner.

 

Skier triggered roller balls on Tenderfoot.


Additional Concern

There are a variety of storm snow concerns today.

Storm Slabs: This warm, wet snow should bond quickly to the surfaces below but the warmer snow over slightly colder snow may create storm slabs. Quick hand pits are a good way to determine if the new snow is sticking to the old snow. 

Wind slabs:  Yesterday above approximately 2200' we received a foot of new snow and sustained winds. It will be possible to trigger a wind slab in steep wind-loaded terrain. Be on the lookout for stiff, pillowed snow and shooting cracks.

Cornices: The fresh snow/wind combination will also add to already large cornices that may be very tender due to warm temperatures. Avoid travel on or below these behemoths.

Persistent Slab: In areas outside of our core forecast zone, including South of Turnagain Pass and the Summit Lake area, the snowpack is shallower and harbors various weak layers; the most notable weak layer is a layer of buried surface hoar 2-3' deep in the pack. We have found these to be unreactive in the past week but with the warm weather and additional load they could re-activate. For more information see this report from the Lynx Creek drainage and the avalanche triggered January 30th

 

Wind transport in the Alpine on Tenderfoot yesterday.


Mountain Weather

Yesterday was mostly cloudy and rain and snow fell throughout the day. The area recieved 1-2" of water, with snow falling above 2200'. Winds were from the ENE blowing in the 30s(mph) for most of the day and gusting into the 70s. Tempertatures were in the 30Fs. 

Today will be mostly cloudy with another few inches of snow possible or rain showers depending on elevation. Rain/snow line is again forecasted to be around 2200'. Winds will be Easterly 15-30 mph. Temperatures will be in the 30Fs. 

Tonight will be slightly cooler and rain/snow showers will continue into tomorrow as the overall pattern persists into the weekend.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  33  0  1 102 
Summit Lake (1400')  35  0 .3  31
Alyeska Mid (1700')  33  1.5 1  87

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  26  ENE 25   71
Seattle Ridge(2400')  28  n/a n/a  n/a 

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: Feb 09, 2016 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenJohnson Pass is OPEN for motorized use. Please DO NOT park in the turnaroud (near restroom) at the trailhead. Snowmachine access is through the (open) gate down the wagon road. Do not travel on the summer route as this is a non-motorized trail.
Placer River: ClosedInadequate snow at sea level.
Skookum Drainage: ClosedInadequate snow at sea level.
Turnagain Pass: OpenTurnagain Pass is OPEN for motorized use. Early season conditions still exist including creek beds and open water hazards in the flats. Please stay off of "Rookie Hill" (small feature directly out of the parking lot).
Twentymile: ClosedInadequate snow at sea level.
Seward District
Carter Lake: Open
Lost Lake Trail: ClosedDue to inadequate snow conditions and to prevent resource damage, operating or possessing a snowmobile on Lost Lake Trail is prohibited. Conditions will be monitored daily for a re-opening.
Primrose Trail: ClosedConditions are being monitored for an opening.
Resurrection Pass Trail: ClosedConditions are being monitored for an opening.
Snug Harbor: OpenPark in the lot at mile 9. No place to turn a truck around after this parking lot.
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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