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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Thu, November 12th, 2020 - 7:00AM
Expires
Fri, November 13th, 2020 - 7:00AM
Forecaster
CNFAIC Staff
Conditions Summary

UPDATE:  7am Thursday, November 12

 

November is proving its worth! After 16-24″ of snow fell last weekend, snow has been falling again since Tuesday night. Looking at our storm total so far, upper elevations above the precipitation stations are estimated at 2.5′ in the high terrain around Portage Valley, 2′ in upper Girdwood Valley and 16″ at Turnagain Pass. Strong easterly winds accompanied the snowfall Tuesday night, but have been moderate (10-20mph with gusts in the 30’s mph) for the past 24 hours. This is all great news, but remember it comes with some avalanche issues discussed below.

Temperatures have been trending upwards overnight and a rain/snow mix is occurring at sea level along Turnagain Arm. Another 2-5″ of snow is expected through today before this final pulse of moisture moves out and clear(ish) skies move in for this weekend. Winds are expected to continue to decrease and blow from the north in the 5-15mph range today and increase to the 20’s mph tomorrow.

The snowpack is building. Roughly 2-3′ exists above 2,500′ and around 2′ at 2000′. Check out Andy Moderow’s report from Tincan yesterday (thanks Andy!). The strong winds have redistributed much of the snow above treeline and so depths are quite variable.

Snowpack structure: The main issue is a thin layer of facets (2-4″ thick) under a crust at the base of the snowpack. This is the culprit for all the ‘whumpfing’ that has been seen above treeline. These facets don’t exists below 1800′. Above the crust, the snow is showing signs of bonding to itself in areas where winds are not creating fresh wind slabs. Hence the two avalanche problems to watch out for are:

Persistent Slab avalanches:  An avalanche releasing in the facets at the bottom of the snowpack. The higher one goes in elevation – above 2,500′ – the more likely it will be to encounter this issue. Whumpfing is a sure sign this layer is reactive. Any snow covered slope is suspect, but wind loaded slopes are the most suspect. If an avalanche releases near the ground it will take the whole pack, resulting in a very dangerous slide.

Wind Slab avalanches:  Fresh wind slabs are likely to be found anywhere the wind has been loading slopes. Keep in mind even a small wind slab, you may not be worried about, could step down and trigger a larger avalanche due to the problem mentioned above.

RED FLAGS:  Recent avalanches, whumpfing (collapsing) in the snowpack and cracks is the snow that shoot out from you are all signs an avalanche could be triggered. Despite the early season thin snow cover, there is now plenty of snow to slide. It’s worth being very suspect of slopes moving forward as skies clear and travel in the Alpine is easier.

Snowpack at 2,600′ on Tincan. Note the sugary snow (facets) at the base of the pack. (Photo: Andy Moderow)

 

The mountains are getting whiter – but don’t forget about the facets below! (Photo: Andy Moderow) 

 

Storm totals from Tuesday night (11/10) through 6am Thursday morning (11/12):
Alyeska mid-mountain (1700′): 1.5″ SWE with 15″ snow
Portage Valley (115′):  2.3″ mostly rain/snow mix
Turnagain Pass (1800′): . 1″ SWE with 12″ snow
Summit lake (1400′): . .3″ SWE with 2″ snow

 


Avalanche Center Operations:  We will continue to provide conditions updates and are planning on issuing the first forecast around Thanksgiving.

Getting into the mountains? Please send us your snow/avalanche reports so we can post them on our observation page! Simply click ‘submit observation’ under the Observation tab. This is a huge benefit for the community and our forecasters.

*Keep tabs on early season conditions and events on Facebook and follow us on Instagram.*


EVENTS:

From Friday, November 6th – Check out the recording of the 2020 Virtual Southcentral Alaska Avalanche Workshop (SAAW). HERE.

Thursday, Nov 19:
SNOW STORIES III
The 3rd annual fundraiser will have an amazing line up of storytellers on the virtual stage. Watch Cody Townsend, Elyse Saugstad, Ian McIntosh, Israel Hale and Kathy Still share their personal stories on snow. Anticipate a wild evening of lessons learned, adventure and comradery. Expect to laugh, cry and maybe learn something new.
All proceeds made from ticket sales go to the Chugach National Forest Avalanche Information Center (CNFAIC).

Cost: 20$. For Zoom tickets register on HERE.

December 1, 15, 29 and January 14:

CNFAIC Forecaster Chat Series – VIRTUAL!
Time:
 7-8pm, Cost: FREE
Forecasters will hold a series of online chats. These will begin with a recap of last season, an outlook for the coming year, and move into an in depth discussion on the various avalanche problems and how they impact the Turnagain Pass region. These are great opportunity to ask questions about specific avalanche conditions and decision-making.

Thanks to our sponsors!
Thu, November 12th, 2020
Weather
Thu, November 12th, 2020

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 32 8″ 0.6″ 26″
Summit Lake (1400′) 32 1″ 0.2 9″
Alyeska Mid (1700′) 32 11″ 1″ ~27″

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 23 ENE 19 65
Seattle Ridge (2400′) 27 E 8 32
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Riding Areas
Updated Thu, November 26th, 2020

Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: mailroom_r10_chugach@fs.fed.us

Area Status Weather & Riding Conditions
Glacier District
Johnson Pass
Closed
Placer River
Closed
Skookum Drainage
Closed
Turnagain Pass
Open
Turnagain Pass open to motorized use as of Wednesday 11/25.
Twentymile
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Seward District
Carter Lake
Closed
Lost Lake Trail
Closed
Primrose Trail
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Resurrection Pass Trail
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Closed for the 2020/21 winter season
Snug Harbor
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South Fork Snow River Corridor
Closed
Summit Lake
Closed

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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.