Avalanche Advisory

Turnagain Area Avalanche Advisory
Monday, December 26th 2016 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

BACKCOUNTRY AVALANCHE WARNING was issued through the National Weather Service yesterday and remains in effect until 6 pm today for the Turnagain Pass area and surrounding mountains. 

Heavy snowfall and strong winds have created a HIGH avalanche danger in the mountains surrounding Turnagain Pass, Girdwood Valley, Portage Valley and areas on the Kenai seeing heavy snowfall. Dangerous avalanche conditions are expected on all slopes 30 degrees and steeper - including runout zones. Large avalanches are expected to release naturally, be easily triggered by people and could run to elevations below 1,000'. 

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.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
Special Announcement

Turnagain Pass is now OPEN to motorized use . This opening happens to coincide with HIGH AVALANCHE DANGER! It is recommended to AVOID AVALANCHE TERRAIN until this storm settles. There is plenty of fun riding to be had in the flats, away from avalanche terrain and runout zones. 

DOT plow drivers are doing their best to keep up with this storm. Keeping the Seward Highway clear is their priority over recreational parking. Please be respectful and avoid parking on the highway! As of last night (11PM) PARKING LOTS HAVE NOT BEEN PLOWED YET AT TURNAGAIN PASS. Berms were too large to drive a truck in. 

Check out the Summit Lake Summary HERE

Avalanche Problem 1

Yesterday natural avalanches 2 ft. deep were observed. These were long running and large enough to bury and kill a person. Cracking and collapsing (whumpfing) were also observed.

Red flags... Rapid loading = Expect dangerous avalanches.

STORM TOTALS in the upper elevations so far:

Turnagain Pass:     30+" and counting, 2.8" of H2O
Girdwood Valley:    20+" and counting,  1.6" of H2O
Summit Lake:         4-6", .4" of H2O

Snow continues to fall with another 1-4" inches expected today.  16"- 20" of snow was measured yesterday on Turngagain Pass. An additional 10+ inches has fallen since then. All of this new snow is forming thick slabs, especially in the alpine where consistent easterly winds have been blowing into the 40's. The weak surface snow and weak snowpack have been rapidly loaded. Expect natural avalanches today and that triggering an avalanche is very likely on any slopes over 30 degrees. Avalanches have the potential to be long running and could be remotely triggered. Avoid travel underneath avalanche terrain as well. This includes the Seattle Ridge up-track and all slopes, gullies and runout zones. 

This needs to be highlighted again today:

Treed areas such as the Tincan Trees:  Storm snow slab avalanches 2-3' thick are likely to be triggered in the trees. The new snow is denser than the underlying old snow - creating an upside down and unstable snowpack. Avoiding slopes over 30 degrees in treed areas is also recommended. Due to the weak faceted snow below the new snow the snowpack is "bottomless". Movement through the snow was challenging yesterday and will only be more of a struggle today. 

Travel in avalanche terrain is NOT recommended. Deep, dangerous avalanches are likely. BE PATIENT. 

Natural avalanche in the Snake Pit on Tincan, 12.25.16. The next gully over also slid. 

Mountain Weather

Yesterday skies were obscured and it snowed or rained depending on elevation throughout the day with periods of heavy precipitation. Easterly winds were in 20s gusting into the 40s. Temperatures were in the 20Fs at ridge tops and in 30s in the valleys. Rain/snowline fluctuated around 500'. The storm continued overnight and temperatures are rising slightly this am. 

Today will be cloudy and another 1-4" of snow is forecasted to fall, rain below 400'. Temperatures are forecasted to hover around freezing, either above or below depending on elevation. Winds will remain easterly 5-15 mph with higher gusts in the alpine. The snow showers are forecasted to continue overnight into tomorrow with temperatures cooling and winds becoming calm. 

Tomorrow is forecasted to be cloudy with a slight chance of snow showers, temperatures in the low 20Fs and light NW winds. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 29   20  2  50 + (estimate)
Summit Lake (1400')  31  2 .2   10
Alyeska Mid (1700') 31   10  .9  32


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') Under repair    Under repair  Under repair    Under repair 
Seattle Ridge(2400') 24  rimed  rimed  rimed 

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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