Sunday, December 21st 2014 6:22 am by John Fitzgerald
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
The avalanche danger in the alpine (2,500-5,000’) is CONSIDERABLE. The chances of triggering an avalanche above 2,500’ are trending towards the low end of the scale but the consequences of being caught remain high. Slabs up to 3’ in depth could be triggered in steep terrain and propagate across entire slopes today.
The avalanche danger is MODERATE in the upper reaches of the treeline (2,000’-2,500’) elevations. It will be possible to trigger slabs 1-2' in depth in steep terrain over 40 degrees. Avalanches triggered in the alpine have the potential to run down into this elevation band today. Triggering an avalanche in the lower portion (1,000’-2,000’) of this elevation band is unlikely today and the avalanche danger is LOW.
Below 1,000’ there is not enough snow cover to issue a danger rating.
|Show the Complete North American Avalanche Danger Scale|
|Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.|
|Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.|
It has now been 5 days since the last storm abated. Slabs up to 3’ deep were dumped on top of a widespread layer of buried surface hoar. This layer has remained intact and is very slowly adjusting to this most recent load. This combination of slab over weak layer is keeping the danger elevated mainly because the consequences remain high if one were to trigger an avalanche today.
On the plus side, the likelihood of triggering an avalanche has been on the decline since this last loading event. As it becomes more difficult to trigger avalanches, it is important to pay attention to and avoid areas where that likelihood is higher. These areas are what we commonly refer to as trigger points.
Here are some examples of trigger points:
Steep rollovers and convex slopes. These features have gravity working against the snowpack making it easier for slabs to release.
Thin spots, where the snow is shallow and weak. In these areas it is easier to impact the weak layer because it is closer to the surface. Exposed rocks and partially wind scoured slopes are where you will typically find these spots.
These are the main areas to avoid today, especially when they connect directly to steeper and bigger terrain. Choosing to recreate on large, open slopes with a variety of slope angles and potential trigger points is a roll of the dice today. You might get away with not triggering a slide or you might not. The best tactic is to hedge your bets by sticking to lower angle non committing terrain and give this slab/weak layer combo more time to heal.
A quick video describing these concepts:
Yesterday was another day of relatively calm weather. Temperatures were in the 20s F at ridge top level, winds were calm and no new precipitation fell during the day.
Light snowfall has begun this morning with stations reporting 1-2” of new snow. Expect to see continued light snowfall as a weak low pressure center spins around the Kenai peninsula today. Accumulation of an additional 1-3" of snow is possible by the end of the day. Winds will be light out of the East at 5 mph. Temperatures at 1,000’ will be right around 32 degrees F.
The extended outlook is calling for a continuation of light snow showers into the early part of the week.
PRECIPITATION 24-hour data (6am - 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880')||29||1||.1||27|
|Summit Lake (1400')||25||trace||.1||4|
|Alyeska Mid (1700')||28||2.5||.2||17.3|
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: Jan 05, 2018 )
|AREA||STATUS||WEATHER AND RIDING CONDITIONS|
|Turnagain Pass:||Open||Turnagain Pass motorized area is open. Early season shallow snow cover conditions exist. Please avoid riding on “Rookie Hill“ and other areas with exposed vegetation. Thank you!|
|Lost Lake Trail:||Closed|
|Resurrection Pass Trail:||Closed||Resurrection Pass trail will be open to snowmachine use during the 2017/18 winter season as soon as conditions warrant.|
|South Fork Snow River Corridor:||Closed|
SNOW AND AVALANCHE HOTLINE (907) 754-2369
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