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Avalanche Advisory

Turnagain Area Avalanche Advisory
Sunday, December 3rd 2017 5:29 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

Strong winds, heavy snowfall and rain expected today and tonight will increase the avalanche danger to HIGH. Naturally occurring avalanches will be likely as the storm pushes in and adds 10 - 20" of snow above 1,000' by this evening. Human triggered avalanches will be very likely and travel in avalanche terrain is not recommended.

Below 1,000' a CONSIDERABLE danger exists where rain is forecast to fall on snow, creating wet loose avalanches. Additionally, debris from avalanches releasing above may run into this low elevation band. This is a significant hazard to ice climbing routes located in avalanche paths. 


 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

**Be aware of changing weather and increasing avalanche conditions across Southcentral, Alaska. This includes elevated avalanche hazard at Hatcher Pass see 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

The first significant storm of the season is on the doorstep this morning, and it's a warm one. Temperatures have begun to climb and winds are picking up from the East. A moisture laden band of snow is on the way from the Gulf and between 10 - 20" of snow is expected today with another 10 - 20" tonight above 1,000'. This is just what the snowpack needs - a big warm storm to hopefully stomp out the shallow, weak and precarious existing snowpack. Not only will this 'rapid loading' event be enough to create natural avalanches in itself, the loading will occur on a VERY weak snowpack making it that much easier for avalanches to release

Again, travel in avalanche terrain during this storm is NOT recommended - in fact, today is a great day for Christmas shopping!

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During the past several days we have seen widespread human triggered avalanches due to our current snowpack structure. The set up is relatively simple, a slab averaging 12 - 20" thick is sitting precariously on a layer of weak facets. Skiers have been able to trigger multiple avalanches from ridges and areas hundreds of feet away - this is how touchy we are talking. With a new load of snow on the way piling up on the existing slab, we can expect the balance to be tipped and widespread natural avalanches breaking near the ground. 

Pre-storm snowpack structure from Sunburst at Turnagain Pass:

 

Tincan Common on Dec 1st - Skiers along looker's right hand ridge, out of view, remotely triggered these three pockets while descending (Victoria Lytle photo)  


Mountain Weather

Yesterday, the mountains saw mostly overcast skies and light snow showers. Turnagain Pass picked up 1" of snow in the past 24 hours and the upper elevations of Girdwood 2-4". Winds during this time were 10-15mph gusting in the 30's and temperatures in the mid 20's F at treeline and the low 30's at sea level.

Today, expect a potent storm day. Around 1+" of rain is expected to fall below 1,000' and possibly 1,500', this translates to 10 - 20" of snow at the higher elevations. Tonight we could see another 1+" of rain and another 10 - 20" of snow. Winds will be Easterly in the 30-50mph range with gusts to 80mph or more. Temperatures should climb to 30F on the 3,500' ridgelines and 40F at sea level. 

Monday, snowfall should taper off and temperatures cool slightly as the storm moves out. We may get a slight bit of visibility Monday afternoon before another front pushes in and a chance for additional snow on Tuesday. This week will be quite active weather wise. Stay tuned!

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

**Seattle Ridge weather station anemometer is covered with rime is not operating at this time. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') *30  1 .1  16 
Summit Lake (1400') 29 .1  10 
Alyeska Mid (1700') 30 .48  19 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 22  NE  19  57 
Seattle Ridge(2400') 25  **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, 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
© 2018 Chugach National Forest Avalanche Information Center. All rights reserved.
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