Monday December 19, 2005 Special Update
Hello and good morning, this is Toby Weed
of the
Mountain Weather:
Late last night, the National Weather
Service issued a Winter Storm Warning for the mountains of
Snowfall in the mountains should subside a bit today before increasing again this afternoon into tonight. Westerly winds will continue to be a factor today and should increase a bit tonight. Temperatures this week will be much warmer than last week's.
Avalanche Conditions:
The backcountry avalanche conditions changed drastically overnight. Last night, warming temperatures caused much heavier snow to fall on top of yesterday's super-light powder, and southwesterly winds picked up significantly. Last night's wind drifted lots of new snow onto lee slope avalanche paths. The wind was also strong enough to build drifts in fetch areas and to cross-load snow around terrain features like sub-ridges, gullies and rock outcroppings. On many slopes, this new load of snow is resting on weak surface snow and buried weak layers formed during last week's cold weather.
You could trigger avalanches today on lots of slopes in the region, with more dangerous conditions in areas that picked up the most snow overnight. Most of today's avalanche activity will include wind-drifted new snow, producing soft slab avalanches 1 or 2 feet deep (and deeper in places). Avalanches today could be pretty wide, with full-width avalanches possible on smoothed-in slopes. Today you should avoid and stay out from under slopes steeper than about 35 degrees with significant deposits of wind-drifted snow. Avalanches are most likely above about 8000' on wind-exposed slopes facing northwest through southeast, but they are possible on most steep slopes in the region.
Bottom Line:
In the backcountry today, there's a CONSIDERABLE avalanche danger on slopes steeper than 35 degrees with significant deposits of wind-drifted snow. This means you could trigger an avalanche on many slopes in the region. Slopes above 8000' facing northwest through southeast are the most suspect. There is a MODERATE danger on steep wind-drifted slopes in the northern part of the forecast zone, (near the Idaho State Line), where much less snow fell overnight.
General Information:
For a list of our upcoming classes and awareness talks, go to our education page
Snow nerds, check out the new Snow Profiles page.
Please send backcountry observations to [email protected], especially if you see or trigger an avalanche in the backcountry.
This advisory will expire on Tuesday morning. But, I will update it again on Tuesday night.
The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.
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National Weather Service - Salt Lake City - Snow.