Wednesday February 6, 2019
Wind Slab, Loose Dry
Travel & Terrain Advice
Ski cuts and slough management will be key this week and into the weekend. This is due to the low density snowfall from the past weekend and the additional incoming snowfall.
Be careful with wind loaded pockets on South to South East aspects, especially near ridge crests and roll-overs and Alpine and exposed Tree-line elevation bands.
Natural point releases have been reported up to size 1 on steep solar aspects. At Mt Washington, Avalanche Control ski cuts produced sloughs on steep unsupported terrain up to size 1. No avalanches observed in the Jutland snowmobile area up from Piggot Creek.
On Tuesday February 5th, Mt Washington ski patrol reported moderate to strong gusts from the north to north west loading leeward aspects and creating wind slabs. It could take up to 48 hours for these wind slabs to settle and bond to the pre-existing snowpack. Given the low density (powder snow) nature, you could expect wind slabs up to size 2.
Loose dry snow remains un-bonded to near surface crust. This powder snow will very likely be triggered on all aspects and all elevations on steep terrain. This problem could be triggered naturally and and as a result of human triggering. Expect the size of loose dry avalanches to be size 1 to size 1.5.
10-30 cm of new snow has fallen since Saturday resulting in a poorly bonded upper snowpack of low density snow. Below the low density snow is an extremely dense crust. The snowpack is generally speaking, extremely well consolidated and is composed of a number of melt freeze crusts. Snowpack tests in the Mt Washington area produced Hard Compression Test Results on a crust down 80 cm, no results were produced during extended column tests. A Surface hoar layer exists down 40 cm from the Surface of the snowpack however it is bonding extremely well due to the warm temperatures. The Alpine areas of Vancouver Island may hold more reactive surface hoar and facets due to the colder temps however we do not have reports that this is the case.
|Surface||10cm - 30 cm of light, fluffy dry snow bonding poorly to crust below|
|Upper||Thick 10cm melt freeze crust|
|Mid||Well bonded midpack that does include two weaker (PWL) layers (Facet layer and Surface layer)|
It has been cold and clear weather generally speaking. No new snow since Sunday. Today February 5th, Mt Washington reported moderate snow transport at Treeline and Alpine from the north to north west.
Generally speaking, the temperatures will remain cool with day time highs below zero into the weekend. More low density snow in the forecasted will combine with last weekends dry snow to create up 40cm of powder snow, and winds will be light from variable directions
Wednesday - No new snow, Temps -15 to -.5, Light Winds shifting from N to S, Freezing level 700M
Thursday - 6 cm of new snow, Temps -9 to -0.1, Light winds shifting from SW to ENE, Freezing Level 700M
Friday - 10 cm of new snow, Temps -15 to -0.9, Light Winds shifting from WNW to ENE , Freezing Level 400M
Posted on Wednesday February 6, 2019 by Ryan Shelly