Update – November 21, 2013

Precipitation forecast to return to the Front Range & Eagle River area Chugach this afternoon and through the weekend.

Snow and the potential for freezing rain is on tap.  Currently the forecast is calling for precipitation to start as snow (Thursday afternoon to evening), transition to freezing rain (late Thursday to Friday afternoon), and then transition back to snow (Friday evening).  The possibility for snow showers will remain through the weekend.

This could lead to increased instabilities within new storm snow due to density differences in the new snow being deposited as temperature and precipitation type fluctuates.  Forecast confidence is high that the Anchorage area will receive at least a few inches of snow and confidence is increasing that we’ll receive at least some freezing rain.  In the event of freezing rain, it could affect even the upper elevations (creating a crust as formed in Hatcher Pass last week) due to warmer air aloft and colder surface temperatures.

Additionally, the snow surface is currently quite variable and in many areas harboring surfaces (unconsolidated and faceted snow, thin layer of facets on top of wind-hardened snow, surface hoar in areas sheltered from wind, exposed rain and melt-freeze crusts) that will provide a weak layer and/or bed surface for new snow to release and slide on.

In general, thin early season snowpacks are weak and more prone to avalanches.  The Front Range and Eagle River area’s thin early season snowpack has been further weakened, and future avalanche problems exacerbated, by the past week of clear and extremely cold weather which has catalyzed faceting and surface hoar growth.

Expect the avalanche danger to increase accordingly towards the weekend with new snow.  We will continue to monitor conditions and will provide an update once we receive precipitation and are able to reassess conditions (likely Saturday or Sunday).

Check out this observation from Wednesday, November 13 to get an idea of conditions prior to the incoming storm.  Keep in mind that much faceting, surface hoar growth, and wind affect has occurred in the meantime.

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