Sun Valley Avalanche Bulletin

This bulletin is from the Sawtooth National Forest Avalanche Center in Idaho.

Sawtooth National Forest Avalanche Advisory

This information 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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Bottom Line by Region:

Human triggered slides are still a concern for wind affected areas.

On east, north and northwest aspects one to two feet of snow has accumulated on weak faceted February snow and surface hoar. Although isolated to only some slopes, it remains possible to trigger a slide on these layers. They are most commonly found in the western Smoky Mountains and out Baker Creek, but it is important to continue to look for and avoid slopes with these weak layers throughout our region.

The danger of triggering a wet slide on steep, sunny aspects will increase with daytime heating. Temperatures promise to get very warm today. Upper elevations remained warmer than the valley bottoms last night so they will heat up faster.

South & Central Wood River Valley: Today the avalanche danger is estimated to be on steep, cooler aspects. About a foot of recent snow sits on top of weak faceted February snow and surface hoar.

Continued reports of collapsing and shooting cracks on north and east facing slopes in this region indicate poor stability.

Recent wind loading is also a concern; a skier triggered slide behind Woodside is evidence of wind blown snow cross loading at mid elevation and bonding poorly to the old snow surfaces.

danger exists on warmer aspects this morning, but the danger of triggering wet slides on steep slopes will increase with daytime heating.

Salmon Headwaters & Sawtooth Mountains: In the Salmon Headwaters the avalanche danger is estimated to be on steep shaded slopes. One and one half to two feet of snow sits on top of weak faceted February snow and surface hoar and it is still possible to trigger slides on this layer. Strong winds and light snow over the weekend have added to this slab and in some cases in exposed locations new wind slabs are poorly bonded to the underlying snow or crusts.

In the Sawtooth Mountains the avalanche danger is estimated to be . A more consolidated, stable snowpack exists in this region but isolated wind slabs and lesser amounts of recent snow on the buried weak layers are of concern.

The likelihood of triggering a wet slide on steep, sunny aspects will increase with daytime heating in all parts of this region. Temperatures promise to get very warm today. Upper elevations remained warmer than the valley bottoms last night so they will heat up faster.

Soldier Mountains: We provide the Bottom Line for the Soldier Mountains on Friday, Saturday, and Sundays at 7:30am. Please continue to read the full advisory as the information may be applicable to this region.

Primary Avalanche Concern:

Persistent Weak Layers: In wind sheltered areas on cooler aspects, the persistent weak layers continue to be a problem and should not be overlooked. In the Central and South Valley, one of our observers reported extensive collapsing and shooting cracks on the north facing slopes out Colorado Gulch. We may think it is March out in the sunshine, but the shady slopes continue to remind us of a cold winter with a shallow snowpack and weak snow. I would be extra cautious in any area with excessively weak snow such as cooler aspects in the Central and South Valley, the side canyons north of Ketchum and in the Pioneer Mountains.

Continue to look for buried surface hoar one to two feet deep in the snowpack on the shady slopes. This layer has been the culprit behind many triggered slides the past few weeks; although gaining strength, it is not gone and can still produce a slide. It is most commonly found on wind sheltered slopes and may be found mid slope even if it is not present on upper portions of the same slope.

Additional Concerns: Upper elevation winds could help to keep things a bit cooler today, but sheltered locations will become quite warm. Id be cautious on the shady aspects with these buried weak layers if it feels unusually warm as it may become easier to trigger a slab avalanche.

Secondary Avalanche Concern:

Current Conditions:

Temperatures at 9,000feet on Baldy and Titus are 27 degrees. Yesterday, temperatures climbed into the mid to upper forties at all elevations.

Southerly winds at upper elevations have increased in speed overnight, blowing 20mph at 7am on Titus and Soldier Mtn. Winds are forecast to be light today, but if they continue to blow they will keep temperatures cooler in exposed areas.

The avalanche conditions may sound complex, but there are some great backcountry options. Sunnier slopes are developing good spring snow conditions which means get on them early as they soften in the sun, get off them before they are wet and sloppy or before you begin punching through surface crusts. If you are searching for powder snow on cooler aspects, moderate slope angles do not pose the risk or require the constant evaluation of slopes steeper than low 30 degree slope angles.

Mountain Weather Forecast:

Expect cloudier skies on Wednesday with continued warm temperatures (but not as hot as today), and a slim chance of light rain and snow showers.

The winds may surprise us today and blow more than expected. The forecast is for southwest winds to remain under 10mph but some of our ridgeline weather stations indicate steady 20mph wind speeds since midnight.

Tip for the Day

Today and tomorrow are great opportunities to get in some practice.

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Reported Conditions

[These open in a new window]

• Titus Peak, Idaho, 10,080'
• Lower Titus Study Plot Idaho
• Sun Valley Bald Mountain, 9000'

Hazard Scale - [Full Size] [Pocket Reference]

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