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Avalanche Forecast

Apr 7th, 2013–Apr 8th, 2013
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
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: South Coast.

Recent snowfall amounts vary considerably from north to south. Danger ratings could be slightly higher in the Cascades where the bulk of the precipitation fell on Sunday.

Confidence

Fair - Due to limited field observations

Weather Forecast

Synopsis: The Cascades could see another 10-15 cm by Monday morning. A brief ridge of high pressure will result in drier conditions and sunny breaks on Monday. The next system arrives sometime on Tuesday bringing moderate precipitation through Wednesday. Monday: Cloudy with sunny breaks. The daytime freezing level rises to around 1500 m. Winds are light from the northwest. Tuesday: Increasing cloud with precipitation developing in the afternoon (~10-15 cm). The freezing level is around 1300-1500 m. Winds increase to moderate or strong from the southwest. Wednesday: Moderate precipitation continues. The freezing level is steady between 1300 and 1500 m.

Avalanche Summary

There are no new reports of avalanches from the region. Watch for an increase in solar related avalanche activity on Monday (loose wet, cornice) and the potential for triggering fresh wind slabs in lee alpine terrain.

Snowpack Summary

Recent snowfall amounts vary depending on location and elevation. Some alpine areas (above 1800-1900 m) could have accumulations of over 40 cm from the past couple days. New dense wind slabs are likely in exposed lee and cross-loaded terrain in the alpine. Most of the recent precipitation has fallen as rain below treeline. Rain had turned to snow down to 1000 m on Sunday morning leaving 10-20 cm of moist snow bonding well to wet grains below. Below the dusting of new snow the upper snowpack at lower elevations has become isothermal from recent warm temperatures and rain. Cornices are very large and could pop off with continued mild temperatures.

Avalanche Problems

Wind Slabs

New wind slabs have formed in exposed terrain at higher elevations. Triggering is possible on steep lee slopes and in cross-loaded gullies.
Be cautious as you transition into wind affected terrain.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4

Cornices

Cornices are large and weak and could pop off with additional growth or daytime warming.
Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 2 - 6

Loose Wet

Loose wet avalanches are possible in steep terrain during sunny periods, primarily at lower elevations.
Watch for wet loose or slab activity with forecast rain and/or warm temperatures.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3