Avalanche Forecast
Regions: South Columbia.
Fresh storm slabs at upper elevations will likely be reactive to human triggers; especially in lee features below ridgetops. Large avalanches could run to valley bottoms.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
SATURDAY NIGHT: Clear / Light, northwesterly winds / Alpine low -2 C / Freezing level 1300 m.
SUNDAY: Sunny / Light, westerly winds / Alpine high 4 C / Freezing level 2400 m.
MONDAY: Cloudy / Light, southwesterly winds / Alpine high 4 C / Freezing level 2400 m.
MONDAY NIGHT: Cloudy with rain/alpine flurries; 5-10 mm / Moderate, southwesterly winds / Alpine low -1 C / Freezing level 2300 m.
TUESDAY: Cloudy with rain/alpine flurries; 5-10 mm. / Moderate, southwesterly winds / Alpine high 2 C / Freezing level 2200 m.
Avalanche Summary
On Friday, Numerous loose wet and slab avalanches to size 2.5 on all aspects in the alpine were reported. Natural and human triggered avalanches will remain likely in the alpine on Sunday. Although not in this region, check out this MIN report from Saturday in Glacier National Park HERE.
Snowpack Summary
20-30 mm. of rain has soaked the snowpack at treeline and below. The rain/snow boundary on Friday was around 2200 m. New snow amounts in the alpine will taper rapidly with elevation and likely equate to around 15-20 cm of moist snow at upper elevations adding to the 20-40 cm recent snow which overlies a crust everywhere except high elevation, north facing terrain where preserved surface hoar (weak, feathery crystals) may be present in isolated locations down 30-60 cm. A similar layer buried in early April is down 50-80 cm. Smaller storm slab avalanches may step down to one of these deeper weak layers.
Below treeline, snow is disappearing rapidly.
Avalanche Problems
Storm Slabs
Fresh storm slabs at upper elevations will likely be reactive to human triggers; especially in lee features below ridgetops. Large avalanches could run to valley bottoms.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Pay attention to changing conditions with elevation/aspect.
- Use small slopes without consequence to test the bond of the recent snow.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Likely
Expected Size: 1 - 3
Loose Wet
If temperatures remain warm, loose wet avalanches are still possible with strong solar radiation; especially in the alpine where there is new snow.
- Avoid terrain traps such as cliffs and gullies that increase the consequence of small avalanches.
- A moist/wet snow surface, pinwheeling and natural avalanches all indicate a weakening snowpack.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood: Likely
Expected Size: 1 - 2