Avalanche Advisory

Turnagain Area Avalanche Advisory
Monday, January 4th 2016 7:00 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

Heavy precipitation and strong winds expected in the Eastern Turnagain Arm area today and tonight will increase the avalanche danger to HIGH at the upper elevations and CONSIDERABLE at the treeline elevations. Natural avalanches are likely and could run into snow-free zones below 1,000' where a MODERATE danger exists. Avalanche activity today will encompass both dry slab and wet snow avalanches. These are not only expected to occur naturally, but human triggered avalanches on slopes 35 degrees or steeper are likely.

*Travel in avalanche terrain is not recommended while the storm moves through the area. Today is yet another day to stick to mellow terrain and stay out from under steep slopes and gullies. This includes avoiding trails running under slide paths such as Johnson Pass Trail and Lynx Creek drainage.

 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.
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.
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Avalanche Problem 1

After a brief break between storms yesterday, yet another warm 'fire-hose' of sub-tropical moisture will be pumping our way today. Easterly winds are just picking up this morning and should reach gale force (or up to a 10 on the Beaufort Scale) by noon on the ridgetops. Precipitation has just begun as well and we can expect 1" of rain below 1,300' and around a foot of snow in the Alpine (another 1" is expected tonight with a rain/snow line dropping to ~600ft). What this all means is another day of HIGH avalanche danger in the mountains.

Avalanche issues today will be similar to those seen since Christmas Eve when this series of storms began. These are: WIND SLABS, STORM SLABS and CORNICE FALLS. Most of the activity we have seen so far has been initiated in the dry snow above treeline. Several slides have been big enough to deposit large amounts of debris at the bottom of the path. Today's storm is just as likely to create large avalanches and until we see a true break in weather, sticking to gentle slopes and areas well away from slide paths will be key. 

Just because you are in the trees and out of the wind doesn't mean the pack is stable; especially in the Summit Lake zone. Here the pack is shallower and harbors more weak layers under the recent storm snow. We went out to look at a snowboarder triggered avalanche from Saturday on Tenderfoot yesterday. What we found was a layer of buried surface hoar existing right around treeline (2,000-2,400') that was responsible for this avalanche. More details on that HERE and HERE

Avalanche Problem 2

With another spike in temperatures, rain up to 1,300' and wet snow to 2,000', we may see additional natural wet avalanche activity below 2,000'. Many of the gullies along the Seward Highway and Seattle Ridge have slide over the past week, wet debris can be seen in the bottom of these. Although most of these slides start as dry avalanches in the Alpine and run into wet snow on the descent, some do initiate below 2,000' as true wet avalanches. Needless to say, steering clear of runout zones is advised.

Additional Concern

Sitting under 5-7' of settled storm snow is a layer of old faceted snow over the Thanksgiving Rain Crust. As we pile more and more load on top of this facet/crust combo, we could see very large avalanches. Some of the large avalanche activity seen during this past week may have 'stepped-down' into this deeper layer. And, just one more reason to let the mountains be as these storms roll through.

Mountain Weather

Yesterday's weather saw intermittent light snowfall above 900' and light rain below this. Accumulation was 0-2". Skies were overcast with a few breaks in cloud cover. Winds were moderate (averaging in the teens with gusts in the 40'smph) from an Easterly direction. Temperatures were in the mid 20's F on the ridgetops and around 32F at 1,000'.

Overnight, temperatures have climbed to 39F at 1,000' on Turnagain Pass (I know, yikes!) and the upper 20's on the ridgetops. Winds are on the rise as well, averaging 40-50mph with gusts over 80mph. This is all in response to another large Pacific storm in the Gulf, which is ushering in sub-tropical moisture, and warm temperatures today. By 6pm tonight we are expecting 1" of rain to fall below 1,300' and up to a foot of snow at the high elevations; another 1" of water (10-12" snow up high) is expected tonight but the rain line should drop to ~600 (which is good news for snow at the parking lots). Winds today will be very strong - averages in the 50'smph with gusts over 90mph.

A break in storm systems tomorrow and Wednesday may allow skies to clear a bit before yet another warm/wind/wet storm arrives on Thursday/Friday.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 29  0.2  85 
Summit Lake (1400') 30  30 
Alyeska Mid (1700') 32   0.2  62


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  24  NE 23  80 
Seattle Ridge(2400') 26  N/A  N/A   N/A  

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 )

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.

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