Avalanche Forecast
Regions: North Columbia.
Minimize exposure to large looming cornices weakening in the sun on Monday. The new snow will be prone to point releases on south facing slopes and wind slabs may be found in immediate lees of exposed alpine terrain features.
Confidence
High -
Weather Forecast
Sunday night: Partly cloudy. Light northwest wind. Alpine temperature -8. Freezing level valley bottom.
Monday: Sunny. Light to moderate west wind. Alpine high temperatures around -2. Freezing level 2000 m.
Tuesday: Increasing cloud. Wind increasing to moderate to strong southwest. Alpine high temperatures around -2. Freezing level 2000 m.
Wednesday: 10-20 cm new snow. Strong southwest wind easing to light. Alpine temperature around -8. Freezing level 1500 m.
Avalanche Summary
Large (size 2-3) natural cornice failures have been reported recently, one on Sunday triggered a 30 cm deep storm slab. A size 2 skier triggered wind slab was reported in neighboring Glacier National Park on Saturday. Natural and skier triggered loose wet avalanches around size 1 have been reported in the past week.
On Tuesday, a skier triggered size 2.5 involvement was reported in neighboring Glacier National Park resulted in lost gear and minor injuries. The avalanche is suspected to have run on a buried crust in the upper snowpack.
Snowpack Summary
10-20 cm of recent snow may have seen some wind effect in immediate less of exposed alpine features. Reports indicate it is bonding well to underlying surfaces which include wind affected snow in the alpine or crust on solar aspects and below 1900 m. Below this elevation and on solar aspects the new snow dusts crusty surfaces down to 1500 m. Below 1500 m, the moist snowpack is quickly diminishing.
At alpine and treeline elevations, a widespread crust exists (except on north-facing slopes above 1800 m) buried 50-100 cm deep. Overall the snow seems to be bonding well at this interface, although there have been a few isolated avalanches running on deeper crust layers over the past few weeks.
Terrain and Travel
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
- Rocks will heat up with daytime warming and may become trigger points for loose wet avalanches
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
Avalanche Problems
Cornices
Cornices become weak with daytime warming. Cornice falls are dangerous in their own right and they can also trigger slabs on slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 2 - 3
Wind Slabs
Wind slabs will be most likely be isolated to immediate lees of ridgecrests and roll-overs in wind exposed alpine terrain.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 1 - 1.5
Loose Wet
Small loose avalanches can be expected in the new snow on steep solar aspects and at elevations where air temperature rises above freezing. Below treeline, loose wet avalanches are possible where snow did not refreeze overnight.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 1.5