Archived

Avalanche Forecast

Apr 5th, 2018–Apr 6th, 2018

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

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

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Inland.

Strong to extreme winds Thursday night and Friday will build wind slabs in exposed terrain at upper elevations. Watch for areas with stiff or chalky looking snow.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

TONIGHT: Flurries. Accumulation up to 4 cm. Ridge wind strong to extreme, southeast. Alpine temperature near -14. Freezing level valley bottom.FRIDAY: Cloudy, light flurries. Accumulation up to 2 cm. Ridge wind moderate to strong, south. Alpine temperature near -10. Freezing level 600 m.SATURDAY: Mix of sun and cloud. Ridge wind moderate to strong, east. Alpine temperature near -5. Freezing level 1100 m.SUNDAY: Cloudy, light flurries. Accumulation up to 2 cm. Ridge wind moderate, southwest. Alpine temperature near -5. Freezing level 1400 m.

Avalanche Summary

A natural, solar triggered size 2 avalanche was reported on Wednesday morning in the Howson range, as well as skier triggered size 1 storm slab releases on a buried sun crust (30 cm deep) on a southeast aspect at 1700 m.Friday of last week, a natural avalanche cycle up to size 2-3 occurred in response to storm snow loading.

Snowpack Summary

From 20 cm up to 40-50 cm of recent storm snow sits above a variety of crusts on all but high north aspects.Weak layers buried around March 19th are roughly 40 cm below the surface. 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

Wind Slabs

Strong to extreme winds and light amounts of new snow will create wind slabs on leeward and cross-loaded slopes at treeline and above.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading has created wind slabs.Be careful with wind loaded areas, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2.5