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Avalanche Advisory

Turnagain Area Avalanche Advisory
Monday, April 1st 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

Another day of VERY WARM temperatures will increase the avalanche danger from LOW this morning to CONSIDERABLE by this afternoon/evening. Dangerous wet loose, wet slab and glide avalanches may release naturally once the sun softens surface crusts and weakens the snowpack. All steep slopes above 1,000' facing East, South and West that see direct sunshine should be carefully evaluated before traveling. Avoid being under glide cracks and give cornices an extra wide berth! 

PORTAGE VALLEY:  Summer trails with avalanche terrain overhead, such as Byron Glacier Trail and Crow Pass, are not recommended in the afternoon or evening due to the possibility of an avalanche occurring above. 

SUMMIT LAKE (& INTERIOR EASTERN KENAI MTS):  Human triggered slab avalanches remain possible in upper elevation terrain on all aspects. This area has a thin snowpack with many weak layers. High elevation sun-affected slopes are the most suspect for triggering a slab. 

SEWARD/LOST LAKE:  The snowpack is warming up and dangerous avalanche conditions are occurring late in the day in this area as well. A large glide avalanche released on Mt. Marathon Thursday


 Show the Complete North American Avalanche Danger Scale
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.
Special Announcement
  • Warm conditions and large avalanches are occurring at Hatcher Pass as well. Be sure to check out yesterday's Hatcher Pass Avalanche Center forecast if you are heading that direction today. 




Avalanche Problem 1

Wet Loose

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Mid-March definitely came in like a lion with all the crazy weather and then March went out like an overheated lamb... Yesterday was the warmest day the advisory area has seen yet. Today should be very similar. Not only are the mid-elevations expected to see wet avalanches, we could see wet avalanche activity on sunny slopes in the high Alpine. Wet loose avalanches will be the most likely, but wet/moist slabs are possible.  The snowpack has already seen many days of a springtime melt-freeze pattern in the low and mid-elevations and with clear skies we did get a freeze overnight. However, with the intensity of the sun and the warm temperatures should be paying close attention to the potential for natural avalanches occurring in the afternoon/evening on solar aspects as crust break down and slopes get mushy. 

A safe day in the mountains includes planning ahead. Don't be an April Fool! Know the terrain you are traveling on and under and if it will be affected by the sun. The boot test is a great way to assess how the daytime warming is, or is not, affecting the surface. If your boot easily sinks into mushy wet snow, it's time to get onto shaded slopes or off the one you are on and well away from any runouts. Wet loose avalanches can start small from a person pushing soft wet snow as they ski or ride. If the terrain is large enough, this small slide can entrain snow and turn into a large and unmanageable avalanche. 

CORNICES: Cornices are very large and direct sunshine will destabilize them. A cornice fall has the potential to trigger an avalanche on the slope below and could break farther back than expected. 

Temperatures on Sunburst (3800') over the last week.  Note the high temperatures yesterday and the lower RH indicating clear skies at night allowing for a solid freeze. 

The avalanche danger on steep slopes on the southern end of the compass will increase to CONSIDERABLE this afternoon/evening. Play the aspects for the best conditions and to stay safe!

 Avalanche carnage on the southerly slopes of Tincan and in the Library. Avalanches from the past week and the storm avalanche cycle the week prior.


Avalanche Problem 2

Glide Avalanches

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Glide cracks are appearing throughout the advisory area and avalanching daily. Avoid traveling under glide cracks! Fresh glides avalanches were observed yesterday at 1:30 pm on Seattle Ridge and one was observed in motion at 4:30 pm on Tincan. The Seattle Ridge full depth avalanche that hit the uptrack Saturday is likely a glide that did not have a crack present before releasing; making our current avalanche situation more unpredictable. Remember, glides can release even if a hard surface crust is present (unlike the wet loose and wet slab avalanche problems). Many cracks are opening up in popular terrain and keep an eye out for them. 

Fresh glide avalanches observed at 1:30 pm yesterday, 3-31-19. These ran over old glide avalanches that released last week. 

 Glide avalanche that released on the uptrack on Saturday at 5:30 pm, 3-30-19. Photo: Travis Smith


Additional Concern

Deep Persistent Slabs

South of Turnagain in Summit Lake and areas in the interior Kenai Peninsula have a very poor snow structure with variety of old weak layers in the mid pack (facets and buried surface hoar.) Triggering a persistent slab 2-3’ deep as slopes warm in the afternoon sun is possible at the upper elevations. The avalanche seen on Butch Mtn. in Summit Lake last week is a good reminder that sunny hot days can surprise us! Keep in mind deeper weak layers could be lurking in these areas and sunlit slopes are the most suspect.


Mountain Weather

Yesterday: Clear and sunny skies with temperatures reaching as high as 40F at 4200' and mid 50Fs at sea level. Winds were light. Overnight temperatures were slightly inverted with valley bottoms seeing high 20Fs and ridge tops low to mid 30Fs. Winds remained light. 

Today: Clear and sunny again with temperatures in the 30Fs to 50Fs and light northwest winds. Overnight temperatures will dip down again in the high 20Fs to mid 30Fs. 

Tomorrow: Clear and sunny with slightly cooler temperatures on tap for Tuesday and Wednesday. There is a chance of clouds on Thursday and maybe a little precipitation but the pattern change is still uncertain. Stay tuned! Finger crossed for spring powder???

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 40   0 67 
Summit Lake (1400')  34    0 21 
Alyeska Mid (1700')  41    0  59  

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 36  variable   13
Seattle Ridge(2400') 39   E  8

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
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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