Avalanche Forecast
Regions: Little Yoho.
Finally a change to the weather. After a dry January (56 cm total at Bosworth), the pattern has shifted and we expect 20-30 cm of new snow and strong winds through Saturday. Avalanche danger may rise quickly as the bond between new and old snow is poor. Small avalanches may run further than expected, even running-out below the treeline.
Confidence
Moderate
Avalanche Summary
No new slab avalanches were observed or reported on Thursday, but the storm was starting and visibility was limited. Our field team reported a lot of loose dry snow (spindrift) blowing around in the cliff and numerous dry loose sluffs starting to run.
Snowpack Summary
15-30 cm of new snow and strong winds will create storm and wind slabs that bond poorly to the underlying snow. Natural avalanches should be expected. The layer being buried on Jan 30 is a mix of crust, surface hoar and facets - none of which will bond well to the new snow. We expect avalanches to begin failing early in the storm with minimal accumulation. Friday and Saturday will be good days to avoid avalanche terrain and evaluate the changes to the snowpack.
Weather Summary
The weather pattern has changed significantly (finally), and there's now a strong onshore flow of moist Pacific air colliding with cold Arctic air. This combination will produce snow. We expect 10-15 cm through the day on Friday. Temperatures will be steady around -12 and winds will be strong from the northwest. The storm ends on Saturday with 25-30 cm total expected, and -25 arrives on Sunday night.
Terrain and Travel Advice
- Storm slab size and sensitivity to triggering will likely increase through the day.
Avalanche Problems
Storm Slabs
New snow combined with wind will create fresh slabs that will release easily as both natural and human-triggered avalanches. Give avalanche terrain a wide berth for a few days to evaluate the impact of the storm. The January 30 layer will be important to watch and monitor how the new snow bonds to it.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Very Likely
Expected Size: 1.5 - 3
Loose Dry
Dry loose avalanches are certain to occur in steep areas, cliffs and gullies as the new snow is coming in cold, will not bond to the old surface and will sluff easily.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Certain
Expected Size: 1 - 1.5