Avalanche Forecast
Regions: Purcells.
If storm totals surprise us and exceed 15 cm Saturday then alpine hazard will be considerable. The region has a weak and highly variable snowpack right now, it may not take much to produce natural persistent slab avalanches, especially if storm totals approach 25 cm.
Confidence
Low - Uncertainty is due to the limited number of field observations. Uncertainty is due to extremely variable snowpack conditions reported through the region. Forecast precipitation (either snow or rain) amounts are uncertain.
Weather Forecast
It’s late November and it looks like we’re entering a more winter-like pattern this weekend. The Purcells (especially the northern section) should get a nice re-fresh from the system.
FRIDAY NIGHT: Trace of snow possible, freezing level near valley bottom.
SATURDAY: Overcast, freezing level around 1000 m, moderate west/southwest wind, 1 to 10 cm of snow possible, with another 2 to 6 cm possible Saturday night.
SUNDAY: Broken cloud cover, freezing level around 1000 m, light to moderate northwest wind, 1 to 5 cm of snow possible.
MONDAY: Broken cloud cover initially with some clearing to scattered in the afternoon, freezing level around 500 m, light northwest breeze, 1 to 5 cm of snow possible.
Avalanche Summary
On Thursday In the central portion of the region a natural size 2 persistent slab avalanche was observed on a north/northeast facing slope at 2300 m. This could be a portent of things to come this weekend, especially if storm snow totals exceed 20 or so centimeters.
Snowpack Summary
Avalanche Problems
Storm Slabs
This is unlikely to be much of a problem Saturday, but it's important to recognize that this is a time of change. If we get surprised with 15 cm or more of snow, watch for a shallow soft slabs and small loose dry avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Unlikely - Possible
Expected Size: 1 - 1.5
Persistent Slabs
Very little is known about some of the crusts in the lower snowpack at this time, but a natural persistent slab avalanche observed Thursday suggests that persistent slabs remain problematic. It's time for conservative terrain choices, as little as 15 cm of snow could induce natural persistent slab avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1.5 - 2.5