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Archived

Avalanche Forecast

Apr 9th, 2018–Apr 10th, 2018
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Inland.

Rising freezing levels, light rain, and the sun's influence are the main concerns for the next few days. Watch for moist or wet snow. Recent wind slabs may also become more sensitive to triggering with the warming trend.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

TONIGHT: Mostly cloudy. Ridge wind moderate, south. Alpine temperature near 0. Freezing level 1600 m.TUESDAY: Cloudy, wet flurries. Accumulation 5-10 cm. Ridge wind strong to extreme southeast. Alpine temperature near 0. Freezing level 1600 m.WEDNESDAY: Mix of sun and cloud. Ridge wind moderate to strong, southeast. Alpine temperature near 0. Freezing level 1500 m. Snow beginning in the evening.THURSDAY: Mix of sun and cloud, snow ending. Accumulation 5-10 cm. Ridge wind light, southwest. Alpine temperature near -2. Freezing level 1200 m.

Avalanche Summary

On Sunday there was a report from the Howson range of a natural, size 2 wind slab release on a wind-loaded, northeast aspect at 2050 m, as well as evidence of previous widespread smaller activity as a result of wind loading.Last week, on Thursday a widespread natural avalanche cycle (up to size 2), triggered by intense wind loading was reported from the northern part of region.While on Wednesday, a natural size 3.5 avalanche that initiated as a storm slab then stepped down to a deeper weak layer, and a solar triggered size 2 avalanche were reported from the Howson range. Skier triggered size 1 storm slab releases on a buried sun crust (30 cm deep) on a southeast aspect at 1700 m were also reported in the same area.

Snowpack Summary

Rising freezing levels and daytime warming have created moist or wet snow surfaces on all but alpine, northerly aspects where 20 cm up to 50 cm of recent storm snow has been redistributed by strong winds. Weak layers buried around March 19th are roughly 40 cm below the surface (up to 100 cm in deeper snowpack areas). These weak layers include surface hoar on shaded aspects at high elevations and hard crust layers on solar aspects and below treeline.Near the bottom of the snowpack, weak and sugary facets are found in shallow, rocky snowpack areas. Storm slabs have stepped down to these facets and producing very large avalanches in northern parts of the region.

Avalanche Problems

Loose Wet

Recent storm snow may become unstable due to rising freezing levels and wet snow or rain. Once moving a loose wet release may have the potential to trigger a slab on a deeper weak layer.
Use extra caution on slopes if the snow is moist or wet.Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.

Aspects: North, North East, East, South East, South.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2

Wind Slabs

Strong to extreme winds have created widespread wind slabs in leeward areas in the alpine. With warming temperatures these slabs may still be sensitive to light triggers, such as a small slough or a skier/rider.
Be careful with wind loaded areas, especially near ridge crests and roll-overs.Pay attention to overhead hazards like cornices which may become weak with warming.

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2.5