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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Thursday, January 15th 2015
Created: Jan 15th 6:21 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
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.
0 NO RATING Below Treeline / Below 1,000'
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Special Announcement

The CNFAIC Avalanche Rescue Workshop schedule for January 18th has been canceled due to lack of snow at the parking lot level in Turnagain Pass. The next hands-on rescue workshop is scheduled for Saturday February 7th.  Please check our calendar for up to date info. 


The Bottom Line

The avalanche danger is MODERATE today across the majority of the forecast area.  Wet loose and glide avalanches will be the primary concerns where rain has barraged the snowpack over the last 3-days. Above 3500’ where we have seen more snow than rain, the danger is CONSIDERABLE as storm snow has fallen on a slick, very supportable crust.  Wind slabs can be expected to continue to build in the 3 -5’ range on Westerly slopes throughout the day and may be reactive to human triggers.


Primary Concern

Another day of warm temps and steady rain continues to test our snowpack and our patience. Expect to put skis on at the snow line, around 1,500’ or higher.  Once on the snow, the primary avalanche concern will come in the form of wet loose avalanches as the pack at these lower elevations is quite saturated and lacks structure.  Several days of rain now has seasoned this elevation band and any wet loose avalanches should be a predictable problem encountered on steep (>35 degree) slopes.  Anticipate these wet loose avalanches and avoid terrain traps if you choose to continue ascending toward higher elevations and winter!  With increased elevation today through the rain zone, the potential exists to trigger a larger, wet (cohesive) slab avalanche where we have more structure in our snowpack.  I’d expect this to be more of an issue in the 2,500 – 3,500’ zone.


Secondary Concern

If you are still climbing and have hit the 3,500’ mark you’ll likely be very wet at this point.  We have very little info from upper elevations since this most recent storm hit.  What we do know is that 4 days ago there was a very supportable surface crust prior to 3”+ of water (estimated 30 – 40” of snow above 3500’) and high winds (40 - 80 mph from the East on Sunburst).  We lack info at this point to understand how well new snow is bonding to the pre-existing surface but expect to encounter fresh, potentially sensitive wind slabs on leeward slopes in the 3 – 5’ range above 4,000’.  It’ll be important to pay attention to any red flags (recent avalanches, cracking or whumphing), conduct your own stability assessment and exercise caution and conservative decision-making if travelling in the highest reaches of the forecast area today.  Dangerous avalanche conditions are likely to exist as we are still within an active weather pattern.

 


Additional Concern

Glide avalanches have been active across the Turnagain zone in steep terrain below 3,000’ since last weekend.  These have been observed littered across the eastern face of Seattle ridge, Eddies (including the final steep pitch on the SW Face), and Corn Biscuit.  Glide avalanches are impossible to predict when they may release so it’s best to simply avoid your exposure to any glide cracks as much as possible.  In channeled terrain, such as below Seattle ridge debris has been observed running out to as low as about 1,200’ (well below the ‘snow-line’).


Mountain Weather

Yesterday marked the 8th day in a row of unseasonably warm temperatures across south-central Alaska with temps at Turnagain pass averaging 37 degrees.  Last night we saw perhaps the peak intensity of this most recent storm with hourly rainfall amounts in the .1 - .2” of water/ hour from Turnagain pass to Girdwood.  Winds also picked up yesterday afternoon from the East with a max gust of 88mph at Sunburst.

Today looks to be more of the same with another 1” or more of water forecasted, moderate winds from the east in the 20-40mph range and unseasonable warm (low 40’s @ 1000’) temperatures.  The rain/ snow line is expected to drop (from roughly 2500’) throughout the day as cooler air aloft filters into our region tonight and the possibility of a rain/ snow mix at 1000’ by the evening hours.

After this current disturbance exits our region this evening we can expect temps to dip slightly to more ‘near-normal’ by tomorrow and a chance of rain/ snow in the forecast thru Sunday.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 35    0  1.8  29
Summit Lake (1400') 36   0 .38 
Alyeska Mid (1700') 36   0 2.3   19

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  28 38 88
Seattle Ridge(2400')  30 NNW  22  62 

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

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
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