Wednesday, April 3rd 2013 6:45 am by Kevin Wright
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
If you haven't already noticed, we've entered a spring pattern of warm days and intense sun affecting the snowpack. The avalanche danger will start the day at LOW and gradually rise to MODERATE as the day heats up. South faces should be avoided late in the day as some natural avalanches have been happening over the last few days.
Other problems can be found on shady aspects, including triggerable wind slab and buried surface hoar.
|Show the Complete North American Avalanche Danger Scale|
|Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.|
The Skookum drainage is now closed to motorized travel for the remainder of the season.
The most notable avalanche we saw yesterday was off Goat Mountain in the Girdwood valley. We believe a cornice failed due to daytime heating and triggered a slab beneath. This is a common occurrence in this place this time of year. The travel distance of the avalanche was impressive, and farther than I've personally seen that path slide.
With continued high daytime temperatures, wet avalanche activity in the afternoon remains the most likely problem to see today. There are numerous examples of this happening over the last few hot sunny days.
Heat induced avalanches are easy to avoid, especially when nighttime temperatures dip below freezing as they are currently. Sometime in the mid afternoon when the snow surface becomes soft or wet, it's time to avoid south faces, including spending time beneath south faces.
The cornice problem is really an extension of the heat problem. As the sun bakes the mountains and temperatures rise in the afternoon, unstable features like cornices lose strength and may fail spontaneously.
This problem can be especially dangerous if they trigger larger slabs on the slopes below, as happened on Goat Mountain yesterday.
Even shady aspects have had some avalanche activity since the last major snowfall. Some of these can be attributed to wind slab over loose near-surface-facets. Yesterday we found a low elevation north aspect slab that failed on buried surface hoar in the Placer valley. Everything we've seen with this character is breaking at the recent storm snow interfaces ~12-24 inches deep. These are common enough that all steep lines should be treated with a degree of respect.
Yesterday the warm and sunny weather continued. Wind up high reached into the teens and 20s overnight. Overall the only weather factor contributing to avalanche danger was the sun and warm temperatures.
Scattered rain and snow showers are forecasted today with mostly cloudy skies. Temperatures are still expected to reach into the 40s at sea level in the afternoon. If the sun doesn't shine today there will be less concern for wet avalanche activity on south faces. Wind should be light from the southeast.
Graham will issue the next advisory on Thursday, April 4th.
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 13, 2019 )
|AREA||STATUS||WEATHER AND RIDING CONDITIONS|
|Twentymile:||Closed||Closed. Forest Service is monitoring conditions.|
|Lost Lake Trail:||Open||Please stay on trail to avoid resource damage through forested areas.|
|Primrose Trail:||Open||Please stay on trail to avoid resource damage through forested areas.|
|Resurrection Pass Trail:||Closed||Closed for the 2018/19 season. Next season will be open to motorized use.|
|South Fork Snow River Corridor:||Open|
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