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Avalanche Advisory

Turnagain Area Avalanche Advisory
Tuesday, March 26th 2019 7:00 am by Aleph Johnston-Bloom
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is MODERATE across the Advisory area today. Warm temperatures and direct sunshine will make triggering a wet loose avalanche possible on steep, solar aspects. Triggering a large, dangerous slab avalanche in the Alpine is also still possible. Choose terrain carefully. Give cornices and glide cracks a wide berth. Pay attention to changing surface conditions.

PORTAGE VALLEY - Byron Glacier trail.  There is a still a chance that direct sunshine and afternoon warming could initiate wet loose avalanches that run to lower elevations or loosen cornices above this terrain. Hiking the summer trail is not recommended. 

SUMMIT LAKE (& INTERIOR EASTERN KENAI MTS):  The snowpack in this zone is shallow and has many weak layers, with the direct sunshine and warm temperatures human triggered slab avalanches remain possible in upper elevation terrain. 

SEWARD/LOST LAKE: Similar to Turnagain -  Human triggered avalanches will be possible will today with warm temperatures and direct sunshine. Extra caution especially on steep, solar aspects in the Alpine is recommended.


 Show the Complete North American Avalanche Danger Scale
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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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Avalanche Problem 1

Wet Loose

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Boom! Sunshine and springtime avalanche conditions are the name of the game now.  After almost two weeks of rain, snow, strong winds and HIGH hazard the snowpack is stabilizing with clear skies and the temperatures dropping below freezing at night. However, there are still some avalanche problems to consider today. Wet loose avalanches will be possible on steep, solar aspects in the afternoon in the Alpine as the colder drier snow becomes wet. Rocky areas are most suspect. Watch for roller balls. The wet loose avalanches may entrain more snow if they gouge into saturated lower elevation snow. After serious concerns about continued natural wet slab avalanches yesterday with all the saturated snow from the weeks of the rain, observers were happy to report a thick supportable melt-freeze crust up to around 2800'. There was also good evidence that the lower elevation snowpack is draining and overall the possibility of triggering a wet slab has significantly decreased. The surface crust may soften by the afternoon and wet loose avalanches are also possible in the lower elevations late in the day as well. Watch for punchy snow and push-a-lanche conditions in steep terrain.  

Crust @ 1500'  at 11 am became soft and punchy at 4 pm. 3-25-19. 


Avalanche Problem 2

Deep Persistent Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Between 2800'- 3000' the snowpack transitions from Spring - supportable crust over moist snow back to Winter (ish) conditions with a drier, colder, deeper snowpack. This colder snow is now getting warmed by direct sunshine and rising temperatures in the Alpine. The warming of the potential slab adds to the lingering concern of triggering an avalanche that fails on an old persistent weak layer. Finding the trigger spot in a thin area could produce a very large avalanche. Signs of instability won't necessarily be present with this type of avalanche problem. Use good travel protocol and think about consequences if a slope does slide. It could be the 1st or 10th skier or machine on the slope that triggers the avalanche. In addition, if traveling in the Alpine look for areas that are more wind-loaded, watch for cracking and listen/feel for hollow snow indicating wind slabs in upper elevation terrain. 

CORNICES:  Cornices are very large and warm air temperatures and direct sunshine could destabilize them today. They have the potential to trigger very large avalanche on the slopes below and break way farther back than expected. Give them a wide berth. 

Snowpit @ 3100', March 8th old snow 100 cm below the surface. 3-25-19

 


Additional Concern

Glide Avalanches

There were multiple glide avalanches during the past week and many glide cracks are opening around the advisory area. These are very unpredictable and not triggered by humans. Glide avalanches fail at the ground pulling out the entire season's snowpack and could be very dangerous. The only way to avoid this hazard is by not spending time under terrain with glide cracks. 

Tincan glide avalanche and cracks, 3-25-19. 


Mountain Weather

Yesterday: Mostly cloudy skies in the morning became mostly sunny by the afternoon. Winds were light in the morning and became calm mid day. Temperatures were in the high 30Fs to high 40Fs at sea level up to mid-elevations. At upper elevations temperatures were in the low 30Fs to mid 20Fs. Skies were mostly clear overnight and temperatures were in the 20Fs and low 30Fs. Most mid and lower elevation weather stations saw temperatures dip below freezing. 

Today: Skies are forecast to be mostly clear and sunny. Winds will be light and northerly. Temperatures will rise by the afternoon to the low 30Fs at upper elevations and the mid to high 40Fs at lower elevations. Overnight should be mostly clear and temperatures should dip down again below freezing. 

Tomorrow: The weather looks to be very similar to today with slightly higher temperatures and a chance of more overnight cloud cover. Sunshine is in the forecast into next week as the high pressure parks over the area. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 35  71 
Summit Lake (1400')  32   24 
Alyeska Mid (1700')  34    0    0   65 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 26  17 
Seattle Ridge(2400')  31   E   10 

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, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: ClosedClosed as of 4.3.19
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: ClosedClosed as of 5/6. Thanks for a great season all, see you next winter!
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Closed
Lost Lake Trail: ClosedClosed as of 3.22.19 due to lack of snow
Primrose Trail: ClosedClosed as of 4.3.19 due to lack of snow
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: ClosedClose as of 5.1.2019
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
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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