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Avalanche Advisory

Turnagain Area Avalanche Advisory
Monday, December 4th 2017 5:32 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

Continued snowfall, rain and wind will keep the avalanche danger at HIGH again today. A warm, wet and windy storm has overloaded the snowpack in the Girdwood, Portage, Turnagain Pass and Kenai Mtn regions. Natural avalanches are expected again today and human triggered avalanches are very likely. Travel in avalanche terrain is NOT recommended

Below 1,000' there is a CONSIDERABLE danger where predominantly rain is falling. Debris running into these lower elevations from avalanches above is likely along with wet loose avalanches on steep slopes. 


 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

**Increased avalanche conditions have been seen across Southcentral, Alaska. This includes elevated avalanche hazard at Hatcher Pass, see recent observations and report at hpavalanche.org.

Motorized use on Turnagain Pass is closed due to insufficient snow cover.  Please see riding area status at the bottom of this page for the most up-to-date information.

Snowmachine Specific – Avalanche Safety and Lessons Learned at AMDS, December 5th @ 6:30 pm - 8:00 pm | FREE Join CNFAIC forecasters at Alaska Mining and Diving Supply for a talk about lessons learned from past avalanche events and get your brain in gear for avalanche season.

The CNFAIC Events Calendar is filling up with avalanche education opportunities. Check it out and find a class that is right for you!


Avalanche Problem 1

As of this morning, the potent storm over us is slowly degrading and exiting. The good news is, winds (that were off the chart yesterday) have decreased overnight and snow is still falling. The rain/snow line is just above 1,000' currently and forecast to lower to around 800' with slightly cooling temperatures. We should see an additional 4-8" through the day at the higher elevations with another 3-4" tonight. Curious of the snow totals so far? 

Estimated Storm Totals (beginning 6am yesterday till 6am today):

Girdwood Valley:  ~2" rain lower elevations, 2-3+' snow high elevations
Turnagain Pass:  1.8" rain lower elevations, 2-3+' snow high elevations
Summit Lake:   .3" rain lower elevations, 3-8" snow high elevations

Recent avalanche activity? There is much uncertainty as to the extent of the natural avalanche cycle yesterday and overnight. As is the case during these stormy conditions, low visibility and darkness hamper visual observations. Nonetheless, we can expect that the mountains are still undergoing significant changes. Upper elevations have seen 2-3+' of feet of snow in less than 24 hours - and it's still snowing and blowing... This is a simple rapid loading event and a text book case for how-to-make-avalanches. Hence, steering clear of avalanche terrain (slopes over 30 deg) with nothing above you (avoiding runout zones) is essential.

 


If we dig a bit deeper into what the mountains are going through and a look to the future, many slopes could be sliding, or will soon, and fill back in. This is what we'd like to see because it helps to clean out the weak layers from November. However, there are those slopes that will hang in the balance and allow the snow to pile up. These are the most likely ones that can get us in trouble when the storm passes. They will still have the weak snow under the new snow, which makes them more susceptible to human triggers, and they will also produce larger avalanches. Telling the difference from slopes that have slid and ones that haven't can be difficult to impossible. Also, just because a slope slid doesn't mean it won't again, especially the first couple days after this cycle. Keep these thoughts in the back of your head as you look forward to enjoying the new snow.  


Mountain Weather

Yesterday's warm storm began around 9 am and as of 6am this morning ~1.5 - 2" of rain has fallen below 1,000' and 2-3+' of snow above. The rain/snow line crept up last night and is hovering just above 1,000'. Winds were some of the strongest we have seen for a while from the East, averaging 40-70mph with gusts over 100. Winds have backed off to the 20-30mph range for averages this morning, remaining from the East. Temperatures have been near 38F at sea level and the upper 20's on the higher ridgelines.

Today, we should see the rain/snow line lower to 800', possibly further, with .4-.5" of rain below and 4-8" of snow above. Tonight cooler air should continue to drop the rain/snow line and an additional 3-4" is possible at sea level with 4-6" at the higher elevations. Winds are forecast to shift Southerly and decrease somewhat to 15-30mph. Temperatures are expected to hover near 38F at sea level and the upper 20's on the 3,500' ridgelines.

Tuesday, the slightly cooler air is expected to stay in place as this system continues its slow exit. We could see continued snowfall with a rain/snow mix at sea level. Looking toward to later this week, warmer air and precipitation looks to filter back our way. Stay tuned.

*Center Ridge SNOTEL is reporting erroneous temperature data. See Turnagain Pass DOT weather station for accurate temperature at 1000'.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') *31  15  1.8  31 
Summit Lake (1400') 34  0.3 
Alyeska Mid (1700') 33  1.7  20 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 24  ENE  59  124!! 
Seattle Ridge(2400') 28  SE  25  61 

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, 2018 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: ClosedClosed as of April 20th
Placer River: ClosedClosed as of April 17th
Skookum Drainage: ClosedClosed as of April 1st.
Turnagain Pass: ClosedClosed as of May 7th. Happy summer, see ya when the snow flies!
Twentymile: ClosedClosed as of April 13th
Seward District
Carter Lake: ClosedClosed as of 4/27
Lost Lake Trail: ClosedClosed as of April 13th
Primrose Trail: ClosedClosed as of April 13th
Resurrection Pass Trail: ClosedClosed as of April 20th
Snug Harbor: ClosedClosed as of 4/27
South Fork Snow River Corridor: ClosedClosed as of April 13th
Summit Lake: ClosedClosed as of April 20th

Subscribe to the Turnagain Area Avalanche Advisory:

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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