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Avalanche Advisory

Turnagain Area Avalanche Advisory
Monday, March 25th 2019 7:00 am by Aleph Johnston-Bloom
Previous Forecast
BROUGHT TO YOU BY
The Bottom Line

The avalanche danger is CONSIDERABLE this morning but will increase to HIGH by this afternoon with direct sunlight and very warm air temperatures making natural large wet slab avalanches likely. This is the first day of sunshine after many inches of rain and feet of snow at upper elevations. The snowpack needs time to adjust, drain and have a substantial overnight freeze. Avalanches could still gouge to the ground, run to valley bottoms and be very destructive. Above 3,000' deep slab avalanches and cornice falls are likely. Once again, travel in avalanche terrain is NOT recommended. 

PORTAGE VALLEY: Very large avalanches could continue to release naturally. Avoid summer hiking trails that travel through avalanche paths, such as Crow Pass, Byron Glacier and Johnson Pass Trail.

SUMMIT LAKE (& INTERIOR EASTERN KENAI MTS):  Despite less precipitation, natural and human triggered avalanches remain likely. The snowpack has many weak layers and the direct sunshine and warm temperatures will keep the hazard elevated in this region.  

SEWARD/LOST LAKE: Similar to Turnagain - the hazard will remain elevated as the potential for natural avalanches will continue today with warm temperatures and direct sunshine. Travel in avalanche terrain is not recommended.

 


 Show the Complete North American Avalanche Danger Scale
4 High Alpine / Above 2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
4 High Treeline / 1,000'-2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
4 High Below Treeline / Below 1,000' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
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Avalanche Problem 1

Wet Slab

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

After weeks of rain and HIGH danger the avalanche advisory may sound like a bit of a broken record. The sunshine and blue skies in the forecast today may be very enticing but the snowpack needs more time.  The rain has essentially made a giant slurpee on the slopes that has been avalanching, gouging to the ground and running to sea level. There was a superficial freeze last night that will quickly deteriorate. Today the slurpee is going to get heated by sunshine and unseasonably warm air temperatures with highs in the 40Fs. Free water running through the snow could stress the snowpack out and trigger large wet slab and wet loose avalanches, especially on solar aspects. Rocky areas and steep slopes in the direct sun will heat up first. Travel in avalanche terrain is not recommended today, this includes runout zones. The snowpack needs a solid freeze and time to drain and adjust. 

Glide avalanches are a totally unpredictable hazard that are also a concern today. There have been a number of glide avalanches throughout the advisory area over that past few days and there are cracks in popular terrain. This is another reason to steer clear of avalanche terrain. Don't mess with the brown frown! 

Lipps, 3-21-19.

Orca, 3-22-19. 


Avalanche Problem 2

Deep Persistent Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Above 3000' and the wet snow hazards the Alpine terrain has received feet of snow with strong winds. There is now a potential deep slab issue. Underneath all the snow the interface with the March 8th old snow is a concern. Buried facets and surface hoar at this interface was the suspected weak layer in the impressive avalanche cycle that occurred before this past week of feet of snow. Today the sunshine and warm upper elevation temperatures could stress the cold snow slabs as well. Large, deep slab avalanches are likely in the Alpine and could occur naturally or be triggered from thin spots by humans on skis or snowmachines. Don't be lured into avalanche terrain today on a quest for spring powder. These slabs could be very dangerous and destructive. Again, the snowpack needs time to adjust. Be patient and remember the travel advice for the day is travel in avalanche terrain is not recommended. 

Tincan North side avalanche on 3-18-19, Photo 3-19-19: Travis Smith. There is the potential for slab avalanches like this in the Alpine today. 


Additional Concern

Cornice

Cornices are very large and warm air temperatures and direct sunshine could destabilize them today. They have the potential to trigger very large and destructive avalanches on the slopes below and break way farther back than expected. Give them a wide berth and recognize that they could release naturally today. 


Mountain Weather

Yesterday: There was mostly cloudy skies with some pockets of clearing and light rain/snow showers. Temperatures were in the 20Fs in the Alpine and the 40Fs at sea level. Winds were easterly 15-25 mph with gusts into the 50s. Overnight skies became broken and temperatures cooled slightly. Easterly winds were in teens with gusts into the 20s. 

Today: Partly sunny skies with temperatures in the 30Fs and 40Fs. Winds will be very light and southerly. Overnight temperatures will be in the high 20Fs to 30Fs with partly cloudy skies. Valley fog is in the forecast as an inversion sets in. 

Tomorrow: Valley fog in the morning with mostly clear and sunny skies with highs in the 40Fs and light north winds. The week ahead looks to very similar as the ridge of high pressure is forecast to sit over the area. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 35    0  0.1  72 
Summit Lake (1400') 34   0 24 
Alyeska Mid (1700') 35   0 0.3  67

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  25  NE  16 55 
Seattle Ridge(2400')  30   SE   12 32 

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 22, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Open
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: Open
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Open
Lost Lake Trail: ClosedClosed as of 3/22. Unfortunately HEAVY rain over the past week has washed much of the snow off the lower stretches of this trail.
Primrose Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: Open
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
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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