April 6, 2013

Advisory based on observational knowledge and weather forecast available at the time of posting.  Accuracy is subject to temporal and spatial variability.  Read the disclaimer and conduct your own assessment of conditions accordingly.  Accuracy expiration is less than 24 hours.



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What you need to know:

A winter weather advisory is currently in effect for the Anchorage Avalanche Center’s advisory zone.

The avalanche danger is increasing and will likely rise to considerable later today where it will remain through the weekend.  Expect the peak in avalanche danger to be late Saturday through early Sunday, as the possibility for well over a foot of new snow is on tap for our local mountains.  If the snow abates Sunday and winds remain light as currently forecast, a decreasing avalanche danger trend should begin later in the day on Sunday as the snowpack begins to adjust to its new load, storm snow and old surface snow has a chance to bond, and a stabilizing trend commences.

Danger trend:

Increasing through Saturday into Sunday.

Primary Concerns:


As of Saturday morning a few inches (3-6) of snow have likely already accumulated higher in the mountains.  It’s still snowing in earnest and is forecast to continue until midday Sunday when the snow should begin to taper off and has less probability of continuing.

Our new snow is falling on a weak surface ranging from a slick and solid to breakable melt-freeze crust on previously sun-exposed aspects (E, S, W) to dry and faceted snow with spotty surface hoar on northerly aspects and in other higher elevation (colder) sheltered areas.

The new snow falling now through Sunday is not likely to bond particularly well to any of the aforementioned old snow surfaces, will need to be approached with caution initially, and assessed thoroughly for real-time concerns during your travels in the local hills this weekend.


Although winds are forecast to be light and remain light for the short term, some moderate winds at the higher elevations are likely and will exacerbate new snow instabilities by creating sensitive wind slabs.  Ridge top weather stations are already reporting gusts on the cusp of moderate and likely strong enough to already be building cornices and soft wind slabs on leeward aspects (north to west, but especially northwest).

Peripheral Concern:


If the weather forecast holds, wet avalanches shouldn’t be a concern in the short term.  However, if the sun comes out, wet avalanches will be a serious issue to contend with considering the new snow that will quickly become wet and be prone to sun-induced shedding in the form of wet-loose avalanches.  Such wet-loose avalanches, should the sun come out and they occur, may even have the potential to trigger other new snow instabilities as they descend.

Travel Advice:

Visibility is likely to remain low through the weekend as the Anchorage area Chugach (Front Range and Eagle River) is enshrouded by this storm.  Low visibility will hide possibly dangerous slopes, their runout zones above and around you, as well as other features of concern that might normally alert you as to lurking avalanche problems.

Be on the lookout for red flags of instability like shooting cracks, collapsing or “whumphing“, and clues as to recent avalanches (likely only to be clues considering the lack of visibility so as to see thoroughly).  In assessing the wind slab concern, be on the lookout for some of the typical characteristics such as a rounded or “pillowy” look and hollow or “slabby” feel.

Mountain Weather:

Expect low visibility with snow continuing steadily until Sunday morning, when forecast to gradually start tapering off.  The potential for 1-2′ of new snow is on tap for the Front Range and Eagle River mountains.  Winds will be predominantly from the southeast and are forecast to blow light to moderate.  Mountain temperatures are likely to be in the lower 20s during the day.

Avalanche Outlook:

Sunday, April 7

Snow should be decreasing in intensity and tapering off through the day.  The peak in considerable avalanche danger may occur early Sunday before beginning the gradually decreasing trend towards moderate by Monday.

Monday, April 8

If the weather forecast (current as of Saturday morning) holds, avalanche danger should be on the decreasing trend and of a moderate nature.

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