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ARCHIVED - Forecasts expire after 24 hours.
Issued
Mon, March 16th, 2015 - 7:00AM
Expires
Tue, March 17th, 2015 - 7:00AM
Forecaster
CNFAIC Staff
Avalanche risk The Bottom Line

The avalanche danger will climb to HIGH in the Alpine and CONSIDERABLE at Treeline by the end of the day.   Slabs up to 18″ thick will be very sensitive to human triggers and could release naturally.  

Dangerous conditions exist and require advanced travel and snowpack assessment skills.   Avalanches have the potential to run through multiple elevation bands.   Because of this, awareness of terrain looming overhead will be critical today and is why the danger will be MODERATE below Treeline in big channeled terrain.

Special Announcements

An avalanche accident involving a snowmachiner occurred over the weekend near Denali National Park.   Our thoughts are with the patient for a full recovery.   More details can be found HERE.

Mon, March 16th, 2015
Alpine
Above 2,500'
4 - High
Avalanche risk
Treeline
1,000'-2,500'
3 - Considerable
Avalanche risk
Below Treeline
Below 1,000'
2 - Moderate
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

Rapid loading as a result of new snow and wind will create unstable conditions today.  Slabs will vary in size and be thickest, up to 18” on leeward slopes.  With wind speeds over 40 mph expect loading to occur lower down on slopes and in areas that are normally protected from the wind.

The danger will be more in the MODERATE range in general this morning.  That will change quickly as the day progresses.  Becasue of this it will be important to pay attention to rapidly changing conditions and pick your terrain carefully.

Recent avalanches, shooting cracks, and collapsing are key indicators of unstable snow.  These signs should dictate where you travel today.  In other words, avoid avalanche terrain if and when you begin noticing these signs.

Travel in the Alpine elevations is not recommended for the latter part of the day.

Weather
Mon, March 16th, 2015

Low pressure currently centered over the Alaska Peninsula has brought precip, wind and warmer temps to the area.   Temperatures over the last 24 hours have seen a dramatic rise with ridgetops moving from 0 to 20 deg F.   Winds have picked up in a similar dramatic fashion, with ridegtops reporting speeds in the 35-40mph range this morning.   Storm totals so far are in the 5 €/.4 € (snow/H20) range.

Today expect snow to be heavy at times with up to 10 €/.9 € (snow/H20) of additional accumulation by the evening.   Winds will be strong out of the East at 30-40mph.   Temperatures will be in the low 30s F at 1,000′.   Rain/snow line will hover between 500-1,000′.

Precipitation will taper off late this evening.   Cloudy and showery conditions will continue through Tuesday with another round of significant precipitation on Wednesday.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 21 5 .3 47
Summit Lake (1400′) 22 1 .1 9
Alyeska Mid (1700′) 21 6 .4 31

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 12 ENE 26 76
Seattle Ridge (2400′) 15 na 24 48
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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.