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Avalanche Advisory

Turnagain Area Avalanche Advisory
Sunday, December 2nd 2018 7:00 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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BROUGHT TO YOU BY
The Bottom Line

The avalanche danger remains MODERATE above 2500’ in the Alpine. Human triggered slab avalanches up to 1-3’ thick remain possible due to a weak layer of snow under the Thanksgiving weekend storm snow. Additionally, watch for wind slabs that could form today, or did yesterday, with the continued southerly and easterly ridgetop winds.


 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.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
0 NO RATING Below Treeline / Below 1,000'
Special Announcement

Hatcher Pass saw snowfall yesterday and is expecting more snow today/tonight - make sure to check out Hatcher Pass Avalanche Center's forecast!! 


Avalanche Problem 1

Persistent Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Snowy skies are in the forecast for today and tonight. Although Turnagain Pass is not favored for this storm, up to 3" could fall by this evening and an additional 3 to 6" tonight. The Portage zone and areas on the southern Kenai should see rain at sea level but up to a foot of snow by tomorrow morning at the mid elevations. The rain line should hover near 1,000' and possibly lower. Will this system start building back the mid elevation snowpack? It could be a start, but another warm system looks to move in Monday night. 

At the higher elevations, even small amounts of new snow will add weight to our existing snowpack. Sitting anywhere from 1 to 3' below the snow surface is a thin layer of weak snow (buried surface hoar) . Friday's earthquake gave this layer a good shake and triggering a large slide may becoming less and less likely, however it is still a concern. We can't forget this layer is there in terrain above 2,500', which can be easy as any obvious signs of instability are not likely to be seen. What we can do is listen for whumpfing, use safe travel protocol and choose lower angle slopes if we wish to avoid any uncertainty. 


Avalanche Problem 2

Wind Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Moderate to strong ridgetop winds from the south and east are again over the area. Wind slabs lurking in catchment zones from yesterday as well as new slabs formed today are possible to find and trigger in steep terrain. Keep an eye out for yesterday's wind loading patterns, which could be obscured by last night's one to two inches of snow. Snowfall should accompany the strongest winds today, which are forecast for the afternoon. 


Mountain Weather

Yesterday:  Mostly cloudy skies were over the area with light snow showers adding 1-2" of snow in the evening. Winds were strong out of the northeast at Sunburst weather station, yet the main flow direction was more southerly. Temperatures were in the low 30's F at most mid and low elevations and in the upper 20's F along ridgelines.

Today:  Another round of light snowfall is expected later today (1 to 3") that could continue through tonight (an additional 3 to 6"). Snow/rain line should hover around 1,000'. This system is coming in from the SW and more favorable for snowfall in the Anchorage area and Hatcher Pass. Associated winds will again be southerly and easterly in the 20-30mph range with stronger gusts. Temperatures will remain in the low 30's near 1,000' and the mid to upper 20's along ridgetops.

Tomorrow:  A short break in weather systems will give us mostly sunny skies for Monday. Models are showing that Monday night clouds and precipitation move back in as another large low-pressure pushes a moist frontal band over Southcentral. 

*Seattle Ridge wind sensor is rimed over.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 32  0.2  12 
Summit Lake (1400') 28  0.1 
Alyeska Mid (1700') 31   0 0.15 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 23  NE  21  56 
Seattle Ridge(2400') 27  *no data  *no data   *no data  

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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