ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Mon, March 10th, 2014 - 7:00AM
Expires
Tue, March 11th, 2014 - 7:00AM
Forecaster
John Fitzgerald
The Bottom Line
The avalanche hazard will be on a quick rise today. This morning the hazard is LOW at all elevations. New snow and wind will bump the hazard to CONSIDERABLE by the end of the day, as a winter storm impacts the area. Snowfall amounts in the 10 € to 14 € range will create slabs that will be very sensitive to human triggers and could release naturally.
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Mon, March 10th, 2014
Alpine Above 2,500'
Considerable (3)
Treeline 1,000'-2,500'
Considerable (3)
Below Treeline Below 1,000'
Considerable (3)
Alpine Above 2,500'
Considerable (3)
Treeline 1,000'-2,500'
Considerable (3)
Below Treeline Below 1,000'
Considerable (3)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
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.
Over the past several days we have been mapping the snow surface. A consistent theme around the forecast zone is a thin layer of weak snow sitting on a crust. This set up by itself is not a concern. Today that all changes as a slab will be sitting on this weak interface by the end of the day.
Snowfall amounts (and intensity) on their own will be enough to create unstable conditions. In areas where this slab/weak layer/crust combo exists, the snow will be very unstable. Avalanche terrain at all elevations will become more prone to activity as the new snow accumulates. As snowfall amounts begin pushing past the 6-8” range, it will become more likely for slabs and loose snow avalanches to occur naturally. Be on the lookout for obvious signs of unstable snow: recent avalanches, shooting cracks, & collapsing/whoompfing. If you start seeing any of these signs, it is time to scale back on terrain choices.
In favored locations and wind loaded areas slabs could grow into the 2 foot range. All slopes above 35 degrees or in the runout of terrain above should be avoided as slabs increase in depth throughout the day.
Weather
Mon, March 10th, 2014
In the past 24 hours ridgetop temperatures have averaged in the high teens F. Winds have picked up overnight and are currently 24 mph at the Sunburst station, 17 mph at Seattle Ridge, and 22mph at Alyeska (Max’s) out of the East. Clouds moved in overnight as the leading edge of a storm made its way into the area.
Winter part 3 has arrived!
A strong Low pressure system South of the Alaska Peninsula is moving towards Southcentral AK. Snow has begun to fall this morning. Expect snowfall intensities to pick up throughout the course of the day. Accumulations of up to up to 14 € (.9″ H20) can be expected by sunset (7:49pm). Ridgetop winds will be moderate to strong out of the East averaging 20-30 mph with gusts to 70 mph. Temperatures at 1,000′ will be in the high 20s to low 30s F.
Snow, which will be heavy at times, will continue overnight and should taper off by Tuesday evening. Another Low pressure system coming from the Southwest will move into the area on Wednesday, bringing another round of snow. An active weather pattern will continue through the week as a series of Lows track through the area.
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff.
Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations.
Riding area questions contact: mailroom_r10_chugach@fs.fed.us
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.
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