Avalanche Forecast

Poor - Timing, track, or intensity of incoming weather is uncertainfor the entire period

A storm is in the region and forecast to continue for a couple of days. By end of the day Monday moderate accumulation of new snow will have occurred . Monday night to Wednesday afternoon: moderate snow easing to light, winds SW 60-100, freezing levels rising to 1800m. Cooler, calmer, and dryer on Thursday but this system has proven to be quite unpredictable so there's a fair amount of uncertainty for the whole period in the Purcells. Check back tomorrow for an update.

We're still pretty light on info from the field but nothing significant to report form the last 24 hours. I got a photo of the skier triggered 2.5 in Rogers Pass from last Friday and I sure wouldn't have wanted to be tangled up in that one. I'll see if I can get permission to post it and you can take look for yourself--check our photo gallery under the library tab and see if it's there. I did talk to one of our field teams in the South Rockies and they could hear natural avalanches running in the Lizard Range. I know that's quite far from here but they're in the same weather pattern so it might be relevant or a precursor. I think we're in for a cycle that will probably start Monday night or Tuesday morning and could last for a few days if the weather forecast is accurate.

On average, snowpack depths are looking like 60-80cm at treeline and probably 100-120 in the alpine as of end of the weekend. That said, distribution is highly variable, so on a small scale you'll likely see bare ground beside areas with well over 200cm of snow while on a larger scale, one mountain or drainage may have significantly more or less than the next. By the time you read this, the current storm will have been going for 12-24 hours so snow depths will have increased accordingly and the upper part of the snowpack will consist largely of new storm snow in sheltered areas and new wind slabs in exposed locations. How much and how widespread this condition is will vary from northern areas (perhaps somewhat less) to the south (likely somewhat more). I expect the storm and windslabs to be reactive for the next few days but I'll update in tomorrow's report if I get more solid data. There's some potential problems at the old/new interface and in the mid-pack including thin crusts and the November surface hoar, on which I think there is now general agreement that it's November 7th and is a persistent weak layer. It may not last as long as true winter surface hoar but it's down 100cm and has been around for 2 weeks so I guess a PWL it is. Even if these layers seem like they've died down a bit in the last few days, I suspect they'll reactivate in the next couple of days, perhaps not on a widespread basis but certainly locally on specific terrain (e.g. especially where no previous activity occurred). The deep snowpack is a bit of a mixed bag well facetted near the ground in many areas although it's possible this is less the case in places where the snowpack depths are deeper. This is a general overview--I'm hesitant to get too specific this early in the season when data is sparse and there's so much variability. If you think I'm out to lunch and want to set me straight: forecaster@avalanche.ca.