A strong storm today and tonight will rapidly increase avalanche hazard in the park. We are expecting widespread natural activity and touchy conditions for riders. Keep your plans flexible and adjust them accordingly.
Weather Forecast
A strong fast moving storm will move across the park today and tonight. The most intense period of the storm will be this afternoon with strong westerly winds, possibly gusting to extreme. Up to 30 cm of snow are forecast for today and another 10 cm tonight. Light snow will continue Saturday with moderate snow for Sunday in the forecast.
Snowpack Summary
10cm of low density snow overnight overlies hard and soft slabs. Hard slabs can be found in isolated lee features in the alpine deposited from southerly winds. Soft slab overlies a surface hoar layer down 30-50cm. This layer has been gaining strength but could still be reactive, especially between 17-1900m and where it sits on a sun crust.
Avalanche Summary
We have not observed any new natural activity in the past few days. There has also been a lack of observation or reports of skier-triggered avalanches on the Feb 12 surface hoar. Both natural and rider-triggered avalanche activity will increase with the incoming storm today. Avalanche control Wednesday produced a several avalanches to size 2.5.
Confidence
Forecast snowfall amounts are uncertain
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.