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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, January 1st 2017
Created: Jan 1st 5:15 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
 Show the Complete North American Avalanche Danger Scale
The Libby Group
Special Announcement

Happy 2017 from the entire Chugach National Forest Avalanche Center crew!!!  The Center has come a long way from its humble roots as a phone line and basic website in 2002 to what it is today.  Our successes are a direct result of an amazing community of skiers, snowmachiners, snowboarders and businesses that support avalanche safety.  Furthermore, we owe much of our success and sustainability to the Board members that make up our Friends group, past and present.  Wishing everyone a safe, successful and happy New Year!

  • **Alaska DOT may not get to clearing the Turnagain Pass motorized lot for the New Year. Please park safely and respect plow operations.

  • Johnson Pass is open to motorized use. Please stay on the designated motorized trail - map HERE. Limited snowpack information remains - please read the advisory below.
  • If heading to Hatcher this New Year - unstable conditions exist - check the Hatcher Pass advisory HERE Mark your calendars for the FREE rescue workshop at Hatcher Pass on January 14th. More info HERE.

The Bottom Line

There is a MODERATE avalanche danger in the mountains surrounding Turnagain Pass on all slopes above 1,000' where winds have affected the snow. Triggering a wind slab avalanche on slopes steeper than 35 degrees will be possible. These slabs are hard and sitting on a variety of weak layers. They also have the potential to be triggering from below or when you are well onto them.  

Summit Lake area on the Kenai:  Heightened avalanche conditions exist - Please see Heather's Snowpack Summary from yesterday if you are considering this zone.

JOHNSON PASS REGION:  This area has a thinner and potentially more dangerous snowpack in open areas where Friday's winds wreaked havoc. Triggering a slab avalanche is possible on steep slopes loaded by winds - these could be pulled down from below and occur on small steep slopes as well. We are in need of information from this zone (Bottomless snow in the alders? Hard wind slab above the trees? Any avalanche activity?) - please considering submitting an observation if you head this way!! 


Primary Concern

The word on the street is Friday's wind event.... Very strong winds from the West and South did a number to the snow surface, the snowpack and triggered numerous natural wind slab avalanches. Certain areas are stripped to the ground while others have sastrugi and rock hard wind drifts 2-3' thick. In general, many slopes sport a variety of 4-8" supportable wind slabs, thinner breakable wind crusts and even some soft snow in between. Don't get too down though, there are zones that managed to survive and harbor soft settled snow, but folks seem a bit reluctant to give up the coordinates. The clear (but warm) weather forecast for the next week may start eating away at the hard surfaces and riding conditions could improve.  (Check out what folks reported yesterday HERE.)

PERSISTENT SLAB AVALANCHES (In our current case: Hard WIND SLABS SITTING ON WEAK SNOW):

What to keep in mind and watch for:

  • Wind slabs are likely to be sitting on any number of weak layers (facets and/or buried surface hoar)
  • Look for hard snow over soft snow - slabs can be strong enough to support the weight of a snowmachine or skier, allowing you onto them before they release
  • Triggering a slab from below is possible
  • Slabs on unsupported slopes in steep rocky terrain are prime suspects
  • Listen for whumphing
  • Look for cracking around your snowmachine, skis, board

It may be a busy New Year's Day - remember safe travel protocols:

  • Expose one person at a time
  • Watch your partners
  • Have an escape route planned
  • Watch for other groups
  • Consider, what will happen if the slope slides?

 
Photo below: Wind damage and older avalanche activity on Magnum's NW shoulder

 

Large natural wind slab avalanche from Friday on the Northerly aspect of Magnum (back along ridge toward Taylor Pass). Crown mostly filled in, debris ran up other side of creek bed near common up-track to Taylor Pass.

 

Illustrating the complex nature of our snowpack and multiple weak layers:  The Alaska Avlanche School Level 1 course had a CT (compression test) that resulted in three weak layers failing simultaneously on the 21st tap! This is a rare test result (top 2 layers were buried surface hoar and bottom layer was basal facets) Details HERE.

 

Summmit Lake area: Anti-tracks on Manitoba Mtn. Similar to scoured areas in Turnagain Pass. (photo J Haffener & S Galoob)

 


Additional Concern

Watch for cornices in unusual places from the Dec 30 wind event. Though these may seem rock hard and welded into place, it's good practice to always give them a wide berth - we do have warm, sunny weather on tap and this can help to weaken them.

Friday's Southwesterly winds across Sunburst ridge attempted to strip the large cornices formed by the predominately Easterly winds.


Mountain Weather

Mostly overcast skies filled the area yesterday. Ridgetop winds were light from the South and West. Temperatures were in the upper 20's F on the ridgelines and lower 20's F in the parking lots.

Today, we should see sunny skies with WARM and breezy conditions. A very warm air mass is over us associated with a "Blocking High Pressure". Temperatures will be near 32F on the ridgelines and in valley bottoms a bit cooler, in the 20's F. Ridgetop winds are slated for 5-15mph from the South and West.

The high pressure in place looks to remain through the week. From the NWS: "there is high confidence in a prolonged dry spell over Southcentral Alaska and Kodiak Island, on the order of 7 days or longer". Yes, not anything snow lovers want to hear. The next chance for snow does not show up in the longer range model runs, yet - fingers crossed!

*The new year is creating a glitch in some weather stations reporting after 11pm. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 28  39 
Summit Lake (1400') 16  12 
Alyeska Mid (1700') 27  27 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 30*  W*  6*  18* 
Seattle Ridge(2400') 32  NE  19 

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: Mar 28, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: OpenPlacer remains open but SKOOKUM DRAINAGE will close to motorized use on April 1st.
Skookum Drainage: OpenSKOOKUM DRAINAGE CLOSES TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Primrose Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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
© 2017 Chugach National Forest Avalanche Information Center. All rights reserved.
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