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Avalanche Advisory

Turnagain Area Avalanche Advisory
Tuesday, April 16th 2019 7:00 am by Heather Thamm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is MODERATE on slopes above 2,500'. Triggering a slab 1-2’ deep is possible on steep Northern aspects in the alpine. Triggering a wet-loose avalanche is possible with daily warming on steep Southern aspects. Pay attention to surfaces conditions and if you notice the snow becoming wet and unsupportable - transition to firmer surfaces. As always, give cornices a wide berth and limit travel under glide cracks.

PORTAGE VALLEY: Cornice fall and/or avalanches from above have the potential to send debris to valley bottoms and into snow-free zones. Traveling along hiking trails, such as the Byron Glacier Trail with steep slopes overhead is not recommended in the afternoon or on rainy days.

LOST LAKE / SEWARD: Similar to Turnagain, wet loose avalanches on sunny slopes are possible with the heat of the day. Dry slab avalanches could be a concern on high elevation northerly slopes.

WEDNESDAY AVALANCHE OUTLOOK:
No avalanche forecast will be issued tomorrow. Similar avalanche conditions are expected Wednesday, Apr 17th. Overcast skies and scattered rain showers may prevent surfaces from re-freezing overnight. Evaluate surface conditions on all aspects and avoid steep terrain if your skis or machine are sinking into wet snow.


 Show the Complete North American Avalanche Danger Scale
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
0 NO RATING Below Treeline / Below 1,000'
Special Announcement
  • Advisories: For the remainder of April, avalanche advisories will be posted 4 days/week (on Tues, Thur, Sat and Sun). The avalanche center will close for the season on Saturday, April 27th when we will post our springtime tips. Thank you everyone for tuning in!
  • Please join the US and Canada in a joint survey looking into how to better serve you – the users!! We want to hear from all backcountry recreationalists, especially those that are just beginning to use the avalanche forecast. The survey takes about 30 minutes. Survey link: HERE.  (Participants will also be entered to win $500, so don’t delay!)


Avalanche Problem 1

Persistent Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

On shaded aspects in the alpine above 3,000', a weak layer of facets and buried surface hoar exists 1-2' below the surface. A layer of buried surface hoar was the culprit in two human triggered avalanches over the weekend in Seattle Creek. Both of these avalanches occurred at 3200’ on North aspects and released on a layer of buried surface hoar sitting on a melt freeze crust. One of these avalanches was triggered at the top of a chute. The other avalanche we suspect was remote triggered from 5-10’ away. In both incidents no one was caught. Yesterday an observer reported whumping and found a weak layer of facets in a hand pit in higher elevations above Girdwood. They also reported a recent large natural avalanche on a West aspect of Raggedtop.  Listening for whumpfing and digging test pits are good ways to gather information. Sticking to safe travel protocol is also wise; evaluate terrain for consequences, expose one person a time, watch partners and have an escape route planned.  

SPRINGTIME CAUTION:

WET LOOSE: The snowpack has gone through a few days of hot sunny weather and freezing overnight. Today looks like our last sunny day this week. Pay attention to surface snow melting later in the day and avoid steep South facing slopes if surfaces become saturated and punchy. The forecast tomorrow has overcast skies and scatter rain showers and a possibility of no re-freeze overnight. It will be key to monitor surface conditions as you travel - even if we don’t see any sun in the next few days.

CORNICES: There are lots of large cornices on ridge tops. These features can heat up with daily warming making them easier to trigger. Give them lots of space.

 

An avalanche in Seattle Creek in -2 Bowl that occurred sometime over the weekend on a NW aspect at 3200'. We suspect this avalanche remotely triggered due to the nearby tracks on the slope. The weak layer was buried surface on a melt freeze crust.

 

An avalanche triggered on Sunday (4/14/19) on a NE aspect at 3200'. On the back side of this ridge is the -2 Bowl avalanche. Although we couldn't access this crown we suspect the weak layer was buried surface hoar.  


Additional Concern

Glide Avalanches

It's been 10 days since our last known glide avalanche, but keep in mind glide cracks are continuing to creep down-hill. As always identify cracks and avoid traveling under their runout. They are unpredictable and can avalanche at any time. 


Mountain Weather

Yesterday: Skies were clear and sunny with a few clouds. Daytime temperatures reached the mid 50Fs at sea level, mid-40Fs at 1000' and mid-30Fs along ridgetops. Overnight temperatures were in the upper-20Fs along ridgetops and in the mid to low-30Fs in the mid and lower elevations. Ridgetops winds were 5-15mph from the East. No precipitation fell. 

Today: Partly cloudy skies becoming mostly cloudy tonight. Scattered rain showers are possible overnight. Temperature in the mid and lower elevations will be in the mid 40Fs to low 50Fs. Upper elevations will range from the upper 20Fs overnight to mid 30Fs during the day. Winds will be 5-15mph from the East. Up to 0.15" rain is possible overnight, 1-2" of snow above 2000'. 

Tomorrow: Expect overcast skies with scattered rain showers most of the day, 0.15" of rain possible, 1-2" of snow above 2500'. Temperatures at sea level will be in the upper-30Fs to upper-40Fs. Upper elevation temps in upper 20Fs to low-30Fs. Rain/snow line may will be between 2000' and 2500'. Easterly winds 5-15mph will remain.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 37  63 
Summit Lake (1400') 35  17 
Alyeska Mid (1700') 36   0 56 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  28 ENE 5 14 
Seattle Ridge(2400') 33  ESE  14 

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 )

AREA STATUS WEATHER AND RIDING CONDITIONS
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.


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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