Avalanche Advisory
| Advisory: Logan Area Mountains | Issued by Toby Weed for January 18, 2013 - 7:17am |
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Above 8,500 ft.
7,000-8,500 ft.
5,000-7,000 ft.
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bottom line There is a MODERATE (or level 2) danger in the backcountry today. Heightened avalanche conditions exist in sunny terrain with saturated surface snow and in previously drifted terrain at all elevations. You could trigger loose wet avalanches or persistent slab avalanches around a foot deep on steep slopes. Natural wet avalanches are possible in steep sunny terrain initiating in cliff bands or from snow falling off trees during the heat of midday. As usual, safer conditions exist in sheltered and lower angled terrain. Evaluate the snow and terrain carefully, avoid steep sun-warmed or previously drifted slopes and terrain traps below, and continue to practice safe travel protocols...
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current conditions It'll be a great day to get up into the mountains for some fresh air, balmy temperatures, and plenty of sunshine. You can still find some nice smooth re-crystallized powder in sheltered terrain and the fast snow makes lower angled slopes fun. In most areas you can still feel a rime crust from last week under a few or several inches of softer snow. Upper elevation terrain exposed to north winds is wind damaged and sunny slopes are beginning to undergo daily melt and refreeze cycles. The Tony Grove Snotel at 8400' reports 29 degrees this morning, there is 45 inches of total snow, and 67% of average water content for the date. The 9700' CSI Logan Peak weather station reports 26 degrees and west winds averaging 20 mph.
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recent activity No new avalanches were reported locally since the storm last Friday. (1-11) Here's a link to our updated avalanche list...
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Avalanche Problem 1over the next 8 hours
| type | aspect/elevation | characteristics |
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Above 8,500 ft.
7,000-8,500 ft.
5,000-7,000 ft.
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description
Mountain temperatures will rise well above freezing for the first time in quite a while today, with high temperatures forecast to be around 40 degrees in the shade at 9000' in elevation. It'll be downright toasty in the sun and with only a light westerly breeze, solar radiation will be magnified in sheltered sunny bowl areas like in a solar oven. Melting will cause the snow surface to become saturated, and loose wet avalanches are likely on steep slopes. Natural wet avalanches are likely during the midday heat where loose snow falls from cliff bands or trees onto steep slope below. Loose wet avalanches are generally manageable from above, but you have to make sure nobody is below because they have the tendency to widen out in descent or run further than expected. Consider and avoid potential terrain traps like gullies or trees below steep slopes.
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Avalanche Problem 2over the next 24 hours
| type | aspect/elevation | characteristics |
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Above 8,500 ft.
7,000-8,500 ft.
5,000-7,000 ft.
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description
Persistent slabs around a foot deep are unlikely in most areas, but still possible at all elevations on previously drifted slopes. Drifts formed on weak sugary faceted surface snow, in many areas capped by a rime crust from January 8th. The very weak and well preserved faceted snow from early January is a persistent weak layer that may haunt us for some time to come. The snow is especially weak at lower and mid elevations and where the snowpack is generally shallow, but. in most areas a slab layer consisting of harder snow above the weakness is lacking. Watch out for old wind slabs on the lee side of major ridges and in and around terrain features like cliff bands, sub-ridges, gullies, and scoops. Avoid stiff drifts on steep slopes, which often appear smooth or rounded and chalky looking, and they sometimes sound rather hollow. Stiff hard slabs might allow you to get out on them before releasing. Although a rather unlikely scenario in these conditions, you might trigger persistent slab avalanches remotely, from a distance or below. Cracking and audible collapsing are red flags.
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weather Expect sunny skies and warming temperatures in the mountains today. High temperatures will approach 40 degrees at 9000', and we'll feel a fairly light westerly breeze. A strong high pressure system will remain over the region with significant warming aloft continuing today. The resulting temperature inversion will persist and cold air and smog will continue to be trapped in the valleys through the weekend and well into next week. We'll find fair weather in the mountains during this time. A weakening disturbance will graze Northern Utah next Wednesday and Thursday, which might bring us a bit of relief from the smog... Check out the new Logan Mountain Weather page...
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| general annoucements Remember your information from the backcountry can save lives. If you see or trigger an avalanche, or see anything else we should know about, please send us your snow and avalanche observations. You can also call us at 801-524-5304 or email by clicking HERE. In the Logan Area you can contact Toby Weed directly at 435-757-7578. I will update this advisory on Monday, Wednesday, Friday, and Saturday mornings by around 7:30... This advisory is produced by the U.S.D.A. Forest Service, which is solely responsible for its content. It describes only general avalanche conditions and local variations always exist. |