Northwest Inland

There is quite a bit of uncertainty about the current snowpack structure complicated by variability regarding where and when it will rain. Forecast avalanche danger ratings are for the worst case scenario where rain falls on dry snow.

Good - Freezing levels are uncertain

By the end of Saturday a series of frontal systems will have brought up to 35 mm of precipitation to the northwest of the region and around 15mm to the area around Smithers. Unfortunately for the southern half of the region, rising freezing levels will mean that much of this will likely fall as rain. A temperature inversion will make freezing rain likely at lower elevations through until early Friday morning.5 to 10 mm of precipitation is forecast for Thursday with a freezing level of 2000m in the South and at valley bottom further north. Another 5 to 10 mm is forecast for Friday as a cold front moves over the region with the freezing level falling to 1500m. The freezing level will continue to drop to 1000m on Saturday when up to 5mm is expected. Winds will remain moderate to strong from the southwest throughout the forecast period.

Warming temperatures, wind, snow and rain are will drive a natural avalanche cycle that I expect to last the next couple of days. Activity over the weekend was mainly limited to short lived storm instabilities although at least one avalanche released on the early February surface hoar.  I suspect that some of the bigger ones that were reported may have stepped down to even deeper week layers.

I've been unable to access any of the weather stations in the region today and so I have based this update to the snowpack summary on Wednesday morning's weather forecast. I suspect that between 5 to 10cm of new snow have now fallen and may sit on a new layer of surface hoar. Deeper in the snowpack there are a number of weak layers although there is uncertainty about which of them are still players, and which are now dormant. The mid-February surface hoar layer is not found everywhere, but where it does exist it is buried between 30 and 70 cm down. The late January crust is probably down 75 to 150cm in the south of the region but is likely shallower in the north. The mid-January rain crust and surface hoar is probably down between 100 and 200cm. Finally, the crust/facet combination from November is near the ground.