South Rockies

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Fair - Freezing levels are uncertain

Overnight and Wednesday: Some very light precipitation with very strong Northwest winds overnight, becoming moderate Northwest during the day. Freezing level rising to about 1800 metres during the day with some sunny periods.Thursday: Light to moderate Northwest winds with thin high cloud and a chance of sunny periods. Freezing level near 2000 metres.Friday: Warm air trapped at higher elevations. Above freezing temperatures in the alpine with sunny periods.

No new avalanches reported. Suspect extreme Westerly winds and warm temperatures have developed hard wind slabs. Areas with snow available for transport may have continued to experience natural wind slab avalanches. Forecast warm temperatures, limited precipitation, and continued very strong winds are expected to develop hard wind slabs and decrease natural avalanche activity. Avalanches that are triggered are expected to be large due to the amount of recent storm snow. Large storm snow avalanches may step down to buried persistent weak layers resulting in very large destructive avalanches.

Intense snow transport was reported from the Flathead area on the weekend. Expect extensive wind transport and wind slab development in all areas of the region. Recent storm snow varies from 40-70 cm across the region and I suspect that in some alpine areas storm snow has been transported into slabs that are more than a metre thick. Persistent weak layers of buried crusts/facets/surface hoar continue to be a concern, and may have been the failure plane for recent large natural avalanches. Very warm and windy conditions are expected to continue for the next few days. In the long term the warm temperatures should help with some settling and bonding of the buried weak layers. In the short term I don't like the hard wind slabs above weak layers with a rapid change in temperature.