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This is Simon Trautman of the Sawtooth National Forest Avalanche Center with your Backcountry Avalanche Advisory and Weather Forecast for Saturday, February 4, 2012 at 7:30 am.
Sun Valley Company & the Friends of the Sawtooth Avalanche Center bring you this advisory.
Special Announcement:
We are winding up the 6th Annual Avalanche Awareness Week.
There is a free Avalanche Rescue Clinic today from 1-3pm at the Avalanche Rescue Training Park at Baker Creek Trailhead. This will be a great opportunity to practice with your beacon, demo a new one, and learn the basics of avalanche rescue.
The 15th annual Friends Fundraiser, the Best of Banff Film Festival & Incredible Raffle, continues tonight at the NexStage Theater in Ketchum. Doors open at 6pm for a social hour with refreshments and food; the films begin at 7pm. As usual, the Friends will be raffling off an incredible array of amazing prizes, including skis, backpacks, showshoes, avalanche gear, a custom liner and orthotics package, clothing, and tons of gift certificates to local businesses. All tickets go back in the pot for the grand prize, a day of heli skiing for two! Raffle tickets are available at the event, and at Backwoods and the Elephants Perch.
This year's raffle prizes: http://www.sawtoothavalanche.com/docs/Raffle_Prize_List_2012.pdf
Check out this year's film list: http://www.mountain-fever.com/ketchumfilms.html
View this season's film trailer: http://youtu.be/DHDGv1RR2v4
Film tickets are available in advance at Backwoods, the Perch, or Chapter One.
Bottom Line by Zone:
 North Wood River Valley & Salmon Headwaters
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The avalanche danger is MODERATE. Although the likelihood is decreasing, it remains possible to trigger a deep and dangerous avalanche on a layer of facets buried 2-3 feet deep. The greatest risk exists in very steep, alpine-type terrain where trigger points such as shallow and rocky areas are more common. When making decisions, remember that the consequences of triggering one of these deep avalanches is dire. Watch for recent and older wind slabs in upper elevation, exposed terrain. These may remain sensitive, or may be adding additional weight to buried weak layers.
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 South & Central Wood River Valley
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The avalanche danger is MODERATE on mid to upper elevation shady slopes. Although the likelihood is decreasing, it remains possible to trigger an avalanche on very weak, sugary snow buried 1.5-2 feet deep. This poor snowpack structure is more pronounced in the Central Valley, but also exists in the South Valley on slopes that had pre-existing snow prior to the mid-January storms. The greatest risk exists on slopes steeper than 35 degrees, especially those with recent or past wind loading.
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Sawtooth Mountains
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The avalanche danger is MODERATE. Although the likelihood is decreasing, it remains possible to trigger a deep and dangerous avalanche on a layer of facets buried 3-4 feet deep. The greatest risk exists in very steep, alpine-type terrain where trigger points such as shallow and rocky areas are more common. When making decisions, remember that the consequences of triggering one of these deep avalanches is dire. Watch for recent and older wind slabs in upper elevation, exposed terrain. These may remain sensitive, or may be adding additional weight to buried weak layers.
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Soldier Mountains
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The avalanche danger is MODERATE. Although the likelihood is decreasing, it remains possible to trigger a deep and dangerous avalanche on a layer of facets buried 3-4 feet deep. The greatest risk exists in very steep, alpine-type terrain where trigger points such as shallow and rocky areas are more common. When making decisions, remember that the consequences of triggering one of these deep avalanches is dire. Watch for recent and older wind slabs in upper elevation, exposed terrain. These may remain sensitive, or may be adding additional weight to buried weak layers.
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Primary Avalanche Concern:
Winds picked up out of the southeast overnight and undoubtedly created a new pattern of wind slabs on leeward slopes. Expect isolated, but reactive, slabs and drifts on W-N-E slopes near and above treeline. Avalanches in these drifts will not be large, but they will be big enough to cause any amount of trouble in steep, complicated terrain.
Secondary Avalanche Concern:
In the North Valley, Salmon Headwaters, Sawtooths, and Soldiers we continue to be preoccupied with a deep slab stability problem. The layer of concern is 2-4 feet deep, and remains most problematic on mid to upper elevation slopes facing east through north through west. Observations and/or test results show that the faceted layer buried 1-17-12 (and responsible for the post storm avalanching) is gaining strength, and in many places seems to be losing its reactivity ... this hypothesis is best applied to the areas with a deeper snowpack such as the Salmon Headwaters and Sawtooth's. In the area from Galena Pass southwest to Durrance, the lower faceted layers are not as deep, and we are not seeing a corresponding increase in strength in the older basal facets (more specifically at the top of the faceted layer that was buried by December's big storm).
Conditions are very different in the South and Central Valley where the slab is thinner, and a very weak layer of sugary snow is buried 1.5-2.5 feet deep. Steep shaded slopes are most suspect (especially those protected pockets that held snow during the dry spell). The weak basal layer is more developed here than in our northern zones, and you can still trigger an avalanche on steep, exposed slopes where a dense slab remains perched on the weak faceted snow.
Sun Valley Heli reported the recent remnants of 2 slides on SE and East aspects above 9000 feet in the North Valley. Easterly and westerly slopes will be taking a lot of sun and/or radiation during the next several days, and it will be interesting to see how those semi-shaded, or marginal slopes hold up to the heat.
The take home message is that each consequential slope needs to be investigated thoroughly, and independently. We are not quite out of the woods with this deep slab issue. I believe it is still possible to trigger a deep avalanche on certain slopes, and the consequences are dire if you do. Any slope where the lower facets remain weak is suspect. The greatest risk exists in very steep, alpine-type terrain where trigger points such as shallow and rocky areas are more common. If you move into bigger terrain this weekend, choose consistent, supported slopes below 38 degrees in steepness, stay away from rollovers and terrain traps, and have an escape or exit route in mind.
Mountain Weather:
Mountain temperatures are generally in the teens, a pronounced inversion is in place (especially in the Sawtooth Valley where temperatures are well below zero), and skies are clear. Winds picked up out of the southeast after dark, but seem to be lightening this morning.
High pressure continues to build today, and Idaho becomes more firmly ensconced in the 'donut hole'. Upper level flow may back more to the east through the day, and ridgeline winds look light with periods of intermittent gusts. Temperatures rise into the mid to upper 20's in the mountains, and conditions will feel warm on solar slopes.
Welcome to high pressure everybody!
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| Observed Weather |
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| Temperatures |
| Overnight Low |
13 |
17 |
5 |
| 6am Temperature |
14 |
17 |
6 |
| 24 hr Maximum |
19 |
23 |
35 |
| Winds |
| Current Winds |
25 SE |
11 SE |
- |
| 24 hr Average |
17 SE |
10 SE |
- |
| Maximum Gust |
30 SE |
24 N |
- |
| Snow - Storm Interval # 12 |
| New Snow |
0" |
0" |
0" |
| Storm Total |
0" |
0" |
0" |
| Total Depth |
51" |
46" |
27" |
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Announcements:
Your observations are invaluable! Let us know what you're seeing in the backcountry - especially if you see or trigger any avalanches. Call our 24hr voicemail at (208)622-0099 or fill out our observer form on our website:
http://www.sawtoothavalanche.com/submit_observation.php
The Avalanche Rescue Training Park is installed and operational at the north end of the Baker Creek trailhead. Unfortunately, the light and siren are not working at the moment so these won't go off when you probe the target. We're working to get it fixed, but for now have someone watch the screen on the control box and tell you when you've found it.
The Sun Valley Ski Patrol has installed their new beacon practice area in the trees between Christmas Bowl and Christmas Ridge. Stop in at the patrol building atop Baldy with any questions.
The south slopes in Warm Springs are closed to protect wintering elk and deer. This includes the area north of Warm Springs Road from the West Fork of Warm Springs to Ketchum.
For Idaho road closures check http://511.idaho.gov
This advisory only applies to the backcountry and does not apply to highway programs or operating ski areas. Changing conditions and local variations may occur.
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