Avalanche Forecast
Issued: Dec 22nd, 2019 7:40AM
The alpine rating is Storm Slabs, Persistent Slabs and Deep Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeSolar input could initiate another large natural avalanche cycle today!
Deep snow and tree-well immersion is also a very real danger today as the new snow will take time to settle and bond to old layers.
Summary
Weather Forecast
Today will be the first day without any precipitation in some time. A benign weather pattern with cooling temperatures and clearing skies is the trend for this week.
A mix of sun and cloud today. Freezing levels are forecast at 1000m with an alpine high of -6C.
Snowpack Summary
The Atmospheric River dumped 75mm of precipitation since Thursday afternoon. The Dec 11th SH (5-12mm) is now down 90-120cm, and sits on a rounding midpack. The Nov 23 SH/Cr is down 160-185cm. Early season crusts still persist in the lower snowpack.
Avalanche Summary
Over the past two days, two full rounds of artillery control East and West of Rogers Pass summit produced numerous avalanches up to size 3.5 on all aspects and elevations. Slides were releasing in the storm snow then overloading the persistent slab of Dec 11, SH, down 90 - 120 deep.
Confidence
Problems
Storm Slabs
Solar input today could initiate another large natural avalanche cycle! Storm slabs are expected to be widespread and sensitive to human triggering.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
- The new snow will require several days to settle and stabilize.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
The Dec 11th Surface Hoar(SH), size 5-12mm is down 90cm+. This sliding layer was reactive in our control yesterday. Large avalanches will reach valley bottom.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
- Use conservative route selection, choose moderate angled and supported terrain with low consequence.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
The Nov 23 melt freeze crust is down deep in the snowpack. This layer may reach threshold for overload from avalanches triggered in upper snowpack layers or a large cornice release. The resulting avalanches will be very large.
- Use conservative route selection, choose moderate angled and supported terrain with low consequence.
- Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 23rd, 2019 8:00AM