Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Regions
South Rockies.
This bulletin is based on limited data. Local variations in conditions are likely to exist. Check out the Forecaster Blog for further details on interpreting early season bulletins.
Confidence
Poor - Due to limited field observations for the entire period
Weather Forecast
The sunnier drier ridge bringing cooler temperatures at night and mild afternoon temperatures with low winds from the North West is forecasted to last until Wednesday. Increased cloud cover starting to build Tuesday or Wednesday, a sign that the next system is approaching the region. There is not much confidence in the timing of the arrival of the next system, but it looks like it should not effect the conditions covered by this bulletin. Watch for the weather update in the days to come.
Avalanche Summary
There has been a couple second hand reports of large whumphing in the Harvey pass area and triggering a large size avalanche that could have run on the lower November crust. If you and your friends have been out exploring and riding in the backcountry, and have some observations to share please send us an email to [email protected].
Snowpack Summary
The 15 to 30 cm of storm snow that was very reactive yesterday and created up to size 2 natural avalanche in the Lizard range should be in process of settling. However, the afternoon mild temperatures with the sun shining could weaken temporarily the storm slab and the windslabs. The November crust is now below 100 cm in the Alpine and is apparently still active and producing clean shears when tested. This persistent weak layer seems to be found mostly found above 1800m on slopes with smooth ground cover. Below treeline snow levels may just be reaching threshold. If you are traveling in this elevation band, be mindful of obstacles like rocks and trees that could be hiding under a thin layer of snow.
Problems
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.
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.