CNFAIC LogoCNFAIC Logo

Avalanche Advisory

Turnagain Area Avalanche Advisory
Sunday, April 8th 2018 5:11 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
Previous ForecastNext Forecast
BROUGHT TO YOU BY
The Bottom Line

The avalanche danger remains MODERATE on all aspects and all elevations. On Northerly shaded aspects above 1,000', human triggered dry slab avalanches 1-2' thick are possible. On Southerly aspects, wet loose and wet slab avalanches are possible later in the day with daytime warming. If skies remain clear this afternoon, solar warming could increase significantly, increasing the chance for natural wet avalanches and cornice falls. 

Hikers and climbers in Portage Valley: Many popular hiking areas like Byron Glacier trail and even Portage Lake have avalanche terrain above them. Avoid being under large steep slopes where wet avalanche activity is possible in the afternoon and evening. 

For the Summit Lake Summary click HERE. 


 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.
Avalanche Problem 1

Persistent Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Spring has arrived and so has the sunshine. Yesterday was the first warm sunny Saturday of the year. We had reports of relatively small wet loose avalanches on Southerly aspects and one small dry slab on a Northerly aspect (pictured below). 

Triggering a dry slab avalanche remains a concern on shady aspects. These Northerly slopes have between 8" to 2' of soft settled powder from last week's snowfall. This snow fell on a variable old surface sporting everything from hard snow, facets and crusts. Bonding between the new and old snow was initially poor, but has improved over the past couple days. That said, we are still finding facets in areas under the storm snow and finding and triggering a slab avalanche remains possible. One of these was found yesterday on Tincan mentioned above. Getting your shovel out and quick hand pits are ways to help assess if the storm snow is sticking or not where you happen to be. Obvious signs on instability such as shooting cracks and whumpfing may not be present and these pockets could release further down the slope. As always, practice safe travel protocol, expose one person at a time, have escape routes planned and watch your partners. 
 

Deep Persistent Slabs:  Buried in the middle and toward the bottom of the snowpack are old weak layers of facets and buried surface hoar. These layers formed in January and though they have not been responsible for avalanche activity for over a month or more, the springtime warm up can re-activate old layers. Although very unlikely an avalanche will release in these, it's good to remember our snowpack has a poor structure. Most concerning areas are those with a thin snow cover such as the Girdwood Valley and the South end of Turnagain Pass and Summit Lake.

 

 Small slab avalanche triggered remotely on Tincan's Notherly aspect.


-


Avalanche Problem 2

Wet Loose

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Wet avalanche activity will again be a concern later in the day on sunlit aspects. Several wet loose avalanches were seen yesterday both natural and human triggered. All these we know of were generally small and easily avoided. Today will likely be a similar scenario. Temperatures are warm this morning at the higher elevations and even with clouds expected later today, the surface crusts are likely to soften. Once the sun crust melts and the snow becomes wet and 'punchy' to your boot, it's time to head to more shaded slopes. Even a small wet snow avalanche can push you around somewhere you don't want to go.

Wet Slabs: We have not seen any confirmed wet slab avalanche activity yet, but this could be just around the corner. There was a natural slab avalanche on a Westerly aspect in Portage Valley noted yesterday. We don't have quite enough details, but this could be a sign wet slabs may begin to occur if warm days continue. 

 Wet loose avalanches on Pete's South, on the Southerly end of Turnagain Pass. 

 

Slab avalanche seen yesterday in Portage Valley 

-


Mountain Weather

Sunny skies were over the region yesterday. Temperatures climbed into the mid 40's F at 1,000' and near 30F along the ridgetops. Overnight, valley bottoms have cooled into the upper 20's F while warm air streaming in aloft has kept ridgetop temperatures warm. In fact, the Sunburst weather station has jumped from 27F to 32F since midnight. Ridgetop winds were light from the Northwest, in the 5-10mph range, during the day before shifting Easterly along with the warm air moving in around midnight. 

Today, clear skies are expected this morning before cloud cover moves in later in the day. This is associated with a low pressure spinning in the Gulf slowly moving our way. There is a chance for a few snow flurries tonight, adding a trace of new snow (with light rain below 1,500'). Ridgetop winds will remain Easterly in the light to moderate range (5-15mph). Temperatures will again be warm. Ridgetops should see high temperatures in the 30-35F range while valley bottoms warm to the upper 40'sF. 

For Monday and Tuesday, the low pressure system in the Gulf will move in and should keep skies mostly cloudy. There will be a chance for a few inches of new snow above 2,000' and light rain below as temperatures remain spring-like.

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 35  80 
Summit Lake (1400') 34  33 
Alyeska Mid (1700') 35  77 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 28  20 
Seattle Ridge(2400') 32  NW  14 

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: Apr 20, 2018 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: ClosedClosed as of April 20
Placer River: ClosedClosed as of April 17th
Skookum Drainage: ClosedClosed as of April 1st.
Turnagain Pass: Open
Twentymile: ClosedClosed as of April 13th
Seward District
Carter Lake: Open
Lost Lake Trail: ClosedClosed as of April 13th
Primrose Trail: ClosedClosed as of April 13th
Resurrection Pass Trail: ClosedClosed as of April 20th
Snug Harbor: Open
South Fork Snow River Corridor: ClosedClosed as of April 13th
Summit Lake: ClosedClosed as of April 20th

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
© 2018 Chugach National Forest Avalanche Information Center. All rights reserved.
FCNFAIC