Friday, April 15th 2016 6:34 am by Heather Thamm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
Below 2500' the avalanche danger is CONSIDERABLE today due to a continued pattern of warm temperatures and an active glide avalanche cycle. Natural wet loose avalanches in steep terrain are possible and human triggered wet loose avalanches are likely. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential to avoid being under the runout of glide cracks.
In the Alpine the avalanche danger is MODERATE. Human triggered wind slabs are possible on steep leeward slopes and cornices are also a concern for this elevation band along ridgelines.
***Travel is not recommended in avalanche terrain on the West (motorized side of Turnagain Pass).
|Show the Complete North American Avalanche Danger Scale|
|Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.|
|Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.|
- This is the final week of daily avalanche advisories. Between Monday, April 18th and Saturday, April 30th we will be issuing advisories on weekends and intermittently during the week.
- Click HERE to read the accident report of a fatal avalanche accident that killed a snowmachiner in the Hoodoo Mountains, Eastern Alaska Range, on April 3, 2016. This is one of 6 avalanche fatalities in Alaska this winter season.
Yesterday’s unexpected sunny weather and warm daytime temps appear to have accelerated yesterday’s glide activity. Numerous glides released between Turnagain Pass and Girdwood Valley including 3 that were captured by the DOT webcam on Repeat Offender during the heat of the day (2:30pm to 6:30pm.) The fact that we have been experience multiple nights without freezing temperatures in the 1000’-2000’ is concerning. This current snowpack combined with today’s weather (rain and possible sun) has us prepared for another round of glide activity.
Today we will continue to push our message to avoid all slopes with existing glide cracks, including all runout zones. Due to the dangerous and destructive power of even a small glide avalanche, we are recommending that people do not travel in avalanche terrain on the motorized side of Turnagain Pass (this include the up-track). Glide avalanche hazard also exists on the non-motorized side of Turnagain Pass. If you were to be in the wrong place at the wrong time getting caught up in a glide avalanche would not be survivable.
Glide activity yesterday on Repeat Offender, Seattle Ridge, as observed by the DOT web cam.
Close up view of the Seattle Ridge up-track. Notice all of the glide cracks in this area and a natural wet loose avalanche that occured mid day yesterday (4/14)
Yesterday numerous natural wet loose avalanches were observed on Southeast aspects due to intense solar heating. This wet loose activity started around 3pm when temperatures spiked and continued into early evening paralleling yesterday’s glide cycle. Yesterday’s sunny weather was a good reminder of how vulnerable the snowpack is right now in this mid elevation band, where a superficial crust quickly lost its strength.
Below 2000’ overnight temps have remained just above freezing and we have already seen 0.3” of rain in Turnagain Pass and Girdwood Valley. Today we should expect rain and sun, both of which will add stress to the snowpack. If the snow is unsupportable and your skis/snowmachine start sinking into punchy wet snow, this is an obvious sign the snow is loosing its strength. Today it is important to stay off steep slopes below 2500’.
In the Alpine it will be important to be aware of terrain features that could harbor newly formed wind slabs. On leeward aspects and on shaded aspects where the snow is drier, triggering a wind slab (6-10" thick) will be possible. Evaluate snow and terrain features carefully and be on the look out for shooting cracks or blowing snow.
Cornices remain large and warm daytime temperatures will be adding additional stress. Give them extra space and remember they have a tendency to break much further back than expected.
Yesterday skies were mostly sunny and daytime temperatures reached the mid 50F’s near sea level. At Center Ridge Weather station (1880’) daytime temperatures reached a high of 50F at 2pm and overnight temperatures hovered just above freezing. Easterly Ridgetop winds were, 10-25mph. Overnight 0.3" of rain was recorded.
Scattered rain and snow showers are expected throughout the day with mostly cloudy skis, but periods of sun are always possible. Rain/snow line will be around 2500’ with an addition 0.2” of (snow water equivalent) expected today. Ridgetop winds, averaging 10-20mph, will be from the East. Daytime high temperatures for 1000’ are expected to be around 45F and overnight lows in the mid 30F’s.
Similar temperatures and showery conditions are expected through the weekend.
PRECIPITATION 24-hour data (6am - 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880')||38||rain||.3||112|
|Summit Lake (1400')||40||0||0||29|
|Alyeska Mid (1700')||38||rain||.3||97|
RIDGETOP 24-hour data (6am - 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
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).
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: Apr 20, 2018 )
|AREA||STATUS||WEATHER AND RIDING CONDITIONS|
|Johnson Pass:||Closed||Closed as of April 20|
|Placer River:||Closed||Closed as of April 17th|
|Skookum Drainage:||Closed||Closed as of April 1st.|
|Twentymile:||Closed||Closed as of April 13th|
|Lost Lake Trail:||Closed||Closed as of April 13th|
|Primrose Trail:||Closed||Closed as of April 13th|
|Resurrection Pass Trail:||Closed||Closed as of April 20th|
|South Fork Snow River Corridor:||Closed||Closed as of April 13th|
|Summit Lake:||Closed||Closed as of April 20th|
SNOW AND AVALANCHE HOTLINE (907) 754-2369
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