Watch for wind loading at ridgetops, and use caution in wind-loaded features or areas with weak basal facets. These problems are still sensitive to human triggering.
With long nights and cold temperatures on deck, be ready for any unexpected delays.
Happy Holidays from the Banff Visitor Safety Team!
Recent snow and strong NW-SW winds have created small wind slabs in the alpine over the past few days. Watch for wind loading above you, and use caution in lee loaded areas as these still have potential for human triggering. If triggered, these wind slabs could step down to the deep persistent layer.
The bottom layers of the snowpack are facetted and weak in most areas. Human triggering remains possible and this could result in a larger avalanche. Given the unpredictable nature of this problem, use caution when venturing on to any steeper slope with consequence.
Wind loading and the deep persistent facets contributed to a close call near Bow Summit on Dec 23rd.
Over the past couple of days ski hill snow safety teams reported a few size 1-1.5 wind slabs as a result of explosives and ski-cutting work in alpine features and there were a few natural small wind slabs and wind-triggered loose dry avalanches in the alpine.
Newly formed wind slabs can be found in lee aspects at treeline and in the alpine. 5-10 cm of snow sits over the Dec 22 melt-freeze crust that extends to ~1900 m. 15-50 cm of snow sits over the Dec 5 crust that exists to ~2300 m, and is more prevalent in the southern part of the forecast area. The base of the snowpack is a mix of weak facets, depth hoar and a decomposing Oct crust. Low elevations consist of a re-frozen previously wet snowpack.
Treeline snow depths range from 50-95 cm.
Tuesday will be mainly cloudy with scattered flurries leading to trace accumulations. Strong to extreme southwest winds at ridgetop shifting to become west-northwest later in the day. Freezing levels at or near valley bottom.
The overnight low in the alpine is expected to be about -6°C and drop to -10°C during the day.
For more information, click Mountain Weather Forecast.
