South Columbia

Intensity from the sun can make the snowpack weaken and the avalanche danger rise. Be aware of this and keep travel options open to adjust with  change.

Fair - Timing or intensity of solar radiation is uncertain on Sunday

Sunday: As the ridge shifts to the East, the region will remain under a NW flow which will keep alpine temperatures cooler yet we may see a high solar influence. However, some areas may see high cloud cover through the day. Ridgetop winds will blow Light out of the North. Treeline temperatures near -1 and freezing levels rising to 1400 m.Monday: The flattening ridge will start to retreat towards the South allowing a more zonal flow to set up. Ridgetop winds will switch and blow moderate from the West. Treeline temperatures will be near -2 and freezing levels near 1100 m.Tuesday: The pattern makes its change today and a cold front embedded in the zonal flow will move through the region bringing moderate precipitation amounts accompanied by strong winds from the SW. Treeline temperatures will fall to -6 and freezing levels will be near 1400 m.

Natural avalanche activity loose and slab avalanche activity up to size 2.5 continues through the region. Rider triggered avalanches are ongoing and we have continued to receive reports of rider triggered slab avalanches up to size 2. Most of these cases still involving the persistent weak layers below the surface. Avalanche activity may continue through the forecast period, additional concerns being solar radiation as a natural trigger.

20-40 cm of new snow adds to the recent storm slab which sits on a surface hoar layer and a sun crust layer that developed at the beginning of February. This layer continues to be reactive to rider triggers. Deeper down (between 40-80 cm) sits an old sun crust and well preserved surface hoar that was buried on January 23rd. This persistent slab has been reactive and easily triggered over the past few days, especially from solar aspects and at treeline and below treeline over steeper convex slopes. During recent snowpack testing this layer has shown  moderate compression results with sudden planar to resistent planar characteristics. This layer is getting stronger over time and less likely to trigger, but if triggered it will still produce a significant avalanche.Wind slabs exist in specific locations in the alpine and at treeline. The loading pattern may change due to winds switching from the SouthWest to the NorthWest and form pockets of wind slab in unsuspecting places. The mid-pack is well settled and strong. Watch the duration and intensity of the sun in your local riding area; it may weaken the upper snowpack. Cornices loom and threaten slopes below.