North Columbia

Hazard will worsen during the day everywhere with new snow & wind. Con/Con/Mod is for higher snowfall zones where new snow buries a slippery surface hoar layer (e.g. SW Monashees). Farther north, where total recent snow is less than 20cm this past week, hazard Mod/Mod/Low. 

An offshore low will push warm bands of precipitation in upcoming days that are challenging to forecast the precise timing, freezing levels and total snowfall amounts. Where they "stall", higher snow fall amounts will accumulate. In general, total snowfall amounts are for the larger mountains in the Monashees and closer to the Transcanada.

Saturday night: Mostly cloudy with snow flurries, trace -10 cm new snow, moderate southwest ridge wind and alpine low temperature around -7C. (High Res says 20-15cm)

Sunday: Cloudy with snow flurries, 5-15 cm new snow, moderate southerly wind gusting strong and alpine high temperatures around -3C. Freezing level 700-1400 m. (High res says 10-20)

Monday: Southern regions: Heavy snow, 10-20 cm new snow, light southwest wind gusting moderate, alpine high temperatures near -3C and freezing levels rising to 900 m.  

Northern regions: A mix of sun and clouds with isolated flurries and trace to 5 cm new snow, light to moderate southeast wind, alpine high temperatures around -4C with freezing levels 600 m.

Tuesday: Southern regions: Cloudy with snow flurries, 10-20 cm new snow, light to moderate southeast wind gusting strong and alpine high temperatures around -3C with freezing level 700 m.  

Northern regions: Cloudy with sun breaks and isolated flurries, trace new snow, light southwest wind gusting moderate and alpine high temperatures around -6C with freezing levels valley bottom. 

Continued avalanche reactivity is reported from the Gorge in the Monashees. See this MIN from the 30th. Triggering small avalanches on North facing treeline slopes was reported in a couple of locations, including this MIN from the Gorge on the 29th. As more snow adds load to this weak layer, anticipate both the likelihood and consequence of triggering avalanches on this layer to increase. Elsewhere, avalanche active has tapered on Friday and Saturday with little to no new snow, light winds and cool temps. Loose dry avalanches (sluffs) in steep terrain to size 1 of recent low density snow overlying a slippery surface hoar layer continue to be widely reported, particularly below tree line. 

We're continuing to track a layer of surface hoar from early January, the most recent activity reported on this layer was January 17 from Clemina Creek documenting cracking and propagation in sheltered treeline and below treeline areas on surface hoar buried 40-50 cm deep. Although it has followed a trend toward being unreactive, this layer continues to sporadically produce easier, more sudden snowpack test results that make it worthy of continued monitoring.

5-15 cm of snow is forecast to fall overnight Saturday and into Sunday with moderate south winds, burying a surface hoar layer that was reported in sheltered locations at treeline. New snow will add to recent 5 -25 cm of snow from earlier this week that has covered a widespread layer of weak surface hoar. The highest snowfall amounts were reported in the south Monashees while in the far north there are regions with only trace amounts, as reported in this MIN from Clemina. The surface hoar (5-15 mm) that is buried 10-35 cm has recently been most reactive in sheltered north aspects (see avalanche summary). It sits on a variety of surfaces: old wind slabs and wind affect in exposed terrain, a thin sun crust on steep solar and faceted snow. Below 1600 m, 20-30 cm of snow is settling above a decomposing melt freeze crust. 

Observers continue to find a deeper preserved layer of surface hoar from earlier in January down 40-80 cm in sheltered, open slopes at and below treeline. Recent snowpack tests have produced sudden results on this layer, other tests have found it unreactive, as such it continues to warrant slope-specific assessment. 

Deeper in the snowpack are a couple of older persistent weak layers from December (decomposing surface hoar and crust) and early November (crust and facets). Prolonged periods of inactivity and unreactive snowpack test results suggest that these layers have trended towards dormancy. 

• Make observations and assess conditions continually as you travel.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.