Wednesday December 19, 2018
Storm Slab, Loose Wet
Travel & Terrain Advice
Avoid avalanche terrain during the height of the warm wet weather on Thursday. Be conservative, especially in wind loaded areas until the recent storm snow has had some time to become more stable. Pay close attention to signs of stability including recent avalanches, shooting cracks or whumpfing.
A break in the weather on Tuesday allowed some alpine and treeline terrain to be viewed. 1 small (size 1) natural storm slab avalanche about 50 cm deep was observed at 1485 m on a north aspect.
Incoming storm systems will likely continue to create storm and wind slabs at higher elevations especially on lee aspects (NW through NE). These slabs may be large in size (size 2 - 3).
Spiking freezing levels and moderate to heavy precipitation will almost certainly produce small (size 1) loose wet avalanches on all aspects below treeline.
The barrage of precipitation and high winds recently has deposited over 2 m of dry storm snow above 1400 m in eastern areas over the last eight days. Expect depths well over 3 m in western areas in the alpine and on the higher peaks of Strathcona Park. This new snow has been slow to settle at higher elevations and includes several poorly bonding weak layers. High winds have produced thick wind slabs in lee terrain in the alpine and open treeline areas. Below 1400 m, periods of rain and elevated freezing levels will have produced moist snow surfaces.
|Surface||Above 1400 m dry loose storm snow. Wind affected in open areas. Below 1400 m moist to wet snow.|
|Upper||Above 1400 m 60-90 cm of unconsolidated dry storm snow.|
|Mid||Rounding storm snow with varying densities.|
|Lower||Lower 20-30 cm melt freeze crust/facet combo.|
60-90 cm of new snow was deposited at treeline elevations and above since the last bulletin. This new snow accumulation was coupled with strong winds mainly from the SE. Freezing levels were around the 1300 m mark with snow levels resting a few hundred meters below that.
WEDNESDAY - 15-30 mm of precipitation with freezing levels around 1200 m. Winds moderate from the SW veering SE.
THURSDAY - 35-50 mm of precipitation with freezing levels spiking around 1900 m then dropping to 500 m. Winds strong from the west.
FRIDAY - 5-10 mm of precipitation with freezing levels around 600 m. Winds moderate from the SE
Posted on Wednesday December 19, 2018 by Dan Goodwin