Archived

Avalanche Forecast

Jan 19th, 2015–Jan 20th, 2015

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

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

3: Considerable

The avalanche danger rating below treeline will be considerable

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

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Northwest Inland.

Snow, wind, and warming are on the menu this week. Expect slabs to build and avalanche danger to rise.

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Synopsis: The storm track looks like it will be aimed squarely at the Northwest for the next few days bringing a series of frontal systems. Expect 5-15 cm of snow on Tuesday, another 15-30 cm (or mm) Tuesday night through Wednesday, and it keeps coming down on Thursday. We should see a warming trend with freezing levels around 500-1000 m on Tuesday, and 1500-1700 m on Wednesday/Thursday. Winds should be consistently moderate or strong from the SW.

Avalanche Summary

A couple size natural size 2 wind slabs were reported from steep wind loaded terrain (northeast facing) on Sunday.

Snowpack Summary

Strong southerly winds are building wind slabs, generally depositing snow on N and NE aspects (other aspects may be getting cross-loaded or variable local wind effects too, so keep your eyes open). A surface hoar layer was reported to have been buried at the start of January in the northern part of the region. In the mid-pack, a crust weakness buried in mid-December seems to have fallen off most operators' radar for now. Near the base of the snowpack is a November crust-facet combination that could remain problematic, especially in shallower snowpack areas.

Avalanche Problems

Wind Slabs

Forecast snowfall and strong SW winds will build fresh wind slabs in exposed lee terrain and cross-loaded gully features. The size and likelihood of this problem will increase throughout the week.

Avoid freshly wind loaded features.>Use ridges or ribs to avoid pockets of wind loaded snow.>Choose well supported terrain without convexities.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Deep Persistent Slabs

Persistent slabs are most likely to be triggered from shallow snowpack areas, or with a very heavy load (i.e. cornice fall).

Use caution around convexities, ridge crests, rock outcroppings and anywhere else with a thin or variable snowpack.>Be aware of the potential for large, deep avalanches.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 6