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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Saturday, January 21st 2017
Created: Jan 21st 4:24 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.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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Special Announcement
  • TODAY - Join CNFAIC forecasters at the Turnagain Pass motorized lot for a FREE avalanche rescue workshop!! Grab your buddies and practice your rescue skills from 11am-12:30pm before you head out for the day! This is a great opportunity to work on companion rescue with your beacon, shovel and probe and get a little feedback. This workshop is open to everyone and anyone, novices and experts, that recreate in avalanche terrain – snowmachiners, skiers, snowboarders, kicker-builders, etc!! More details HERE.
  • Dangerous avalanche conditions exist in Hatcher Pass. Click HERE for the Hatcher Pass Avalanche Center advisory and HERE for recent snowpack observations.
  • Lost Lake/Snug Harbor is out of the advisory area but has received significant snow from this storm that has fallen on a reported thin/weak snowpack. Expect dangerous avalanche conditions. 

The Bottom Line

There is a MODERATE avalanche danger in the Alpine where triggering a fresh wind slab on leeward terrain is possible and storm slabs could be an issue as the storm progresses throughout the day. If enough snow falls at Treeline and below the LOW avalanche danger could also rise to MODERATE. Watch for changing conditions and don't ignore signs of instability like recent avalanches, cracking and collapsing.

*Periphery zones such as Placer, the Girdwood Valley, Johnson Pass and Summit Lake may have a higher likelihood of triggering a slab avalanche breaking in older weak snow. Approach terrain with a cautious mindset. Practice safe travel protocols, always carry rescue gear and please let us know what you see out there!!

Summit Lake: Higher snowfall amounts fell on a generally weaker snowpack. Please check out the Saturday Summit Summary HERE


Primary Concern

Yesterday winds were moving snow, a few inches of snow fell overnight and more is in the forecast for today. Winds remain strong enough to load slopes. This wind direction is opposite of the wind event on Thursday so leeward slopes will also be opposite. Fresh wind slabs may form throughout the day and be sensitive to triggering. Steep, unsupported, leeward slopes and ridgeline starting zones will be most suspect. There may also be old stubborn wind slabs from previous loading. Be on the lookout for wind transporting snow and pillowed or drifted areas. Avoid places where the snow feels stiffer and more affected by winds and watch for cracking. 

 

 Wind transport on Seattle Ridge yesterday.

 

Cracking in wind affected snow on Tincan yesterday.

 


Secondary Concern

The storm is forecasted to continue today but there is still some uncertainty about how much snow will fall and which sections of the avalanche advisory area will be favored. So far the winner is Summit Lake with 9" overnight.  Center Ridge Snotel has only received 2" so far but expect the southern end of the Turnagain Pass towards Johnson to have higher snowfall amounts already. Turnagain Pass could receive anywhere from 4" to over a foot today. If the upper amounts are received there is potential for storm slab avalanches in places where the new snow doesn't bond to old snow surfaces. In addition to paying attention to new snow amounts watch for temperature changes within the storm. Warmer snow falling on colder snow can quickly make reactive slab conditions. New storm snow will also add to the potential for loose snow avalanches on steep slopes. Paying attention to changing conditions will be crucial today as the avalanche hazard could increase even at lower elevations if this storm produces. 


Additional Concern

A variety of weak layers exist within the snowpack and vary across our region. Following the most recent snowstorm (1/13-1/16) most of the avalanche activity has been observed in the Girdwood Valley. This makes sense since this storm favored this area and left 2-3’ of snow. A handful of small, but deep (to the ground) avalanches were spotted in the alpine this week on Southern aspects of Penguin Ridge, Raggedtop, and Magpie. Summit Lake also had natural avalanches from the Thursday wind event running on weak faceted snow. As more snow falls today remember triggering even a smaller persistent slab could bury a person or take you for a very unfavorable ride over rocks. Pay attention to areas where you can feel weak (sugary) snow under a stiffer snow. If you see recent avalanche activity, experience shooting cracks, or “whumpfing” these are obvious clues that you should avoid steep slopes. 

 


Mountain Weather

Yesterday was mostly cloudy with a few snowflakes falling in the afternoon.  Temperatures were in the high teens to low 20Fs, notably warmer than the previous few days.  Winds were Easterly blowing 15-25 mph gusting into the 30s. 

Overnight a front impacted the area favoring Summit Lake and south. Turnagain received a couple of inches and just inch fell in Girdwood. Snowfall is expected to continue throughout the day will an additional 4-7 inches possible. Winds will be from the SE 5-15 mph with gusts into the 20s. There is some convective potential with this system and overall uncertainty in total snowfall amounts. Temperatures will be in the teens into the mid 20Fs

Tonight snow showers may linger with another 2-4 inches and light E winds. Temperatures will be in the teens. Tomorrow the unsettled weather pattern continues as another system moves towards the region. Stay tuned for snow amounts and temperatures. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  16  2 .2  43 
Summit Lake (1400')  17  9  .9  24
Alyeska Mid (1700')  18  1  .1  38

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  14  ENE-ESE 15  28 
Seattle Ridge(2400')  13  SE  22 35 

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 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
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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