Persistent warm temperatures are penetrating and destabilizing the upper snowpack. Natural avalanche activity is likely. Pay attention to sunny slopes and avoid travel under avalanche paths especially slopes with cornices overhead
Summary
Confidence
High -
Weather Forecast
Hot and sunny with freezing levels through the roof! No significant change during the forecast period. Very little temperature driven overnight re-freeze is expected. TUESDAY: Mostly clear skies and freezing levels holding strong above 3000 m. Alpine temperatures near + 7.0 degrees with a light southeast breeze at ridgetop. Alpine temperatures may drop to + 4.0 degrees overnight.WEDNESDAY: Repeat. Sunny skies with freezing levels above 3000 m. Alpine temperatures +7.0 degrees with light southeast ridgetop winds. Freezing levels may drop to 800 m overnight.THURSDAY: Sunny with some cloudy periods. Alpine temperatures near + 7.0 degrees and freezing levels 2800 m during the day.
Avalanche Summary
On Sunday, natural loose wet avalanches up to size 2 were reported from the region. These avalanches failed on all solar aspects (East through West) between 1600 to 2300 m. Saturday (which was colder and cloudier than Sunday) initiated a natural avalanche cycle that featured loose moist avalanches to size 2.5 on south and southeast facing slopes between 1400 and 1600 m as the old storm snow slid on a crust before stepping down to basal (deep) weak layers.With continued warming and a lack of overnight re-freeze we expect to see widespread natural avalanche activity on all aspects and elevations.
Snowpack Summary
Currently, solar aspects (south and west) are showing signs of melt by day and a freeze by night. In some locations, sheltered northerly aspects have new surface hoar forming and variable wind effect remains on exposed slopes at treeline and in the alpine. The current snowpack is complex and with the continued warming and little overnight re-freeze we're very concerned about the upper 20 to 30 cm of snow that sits on a mix of facets and crust.The bigger questions are deeper in the snowpack. We have at least three prominent weak layers in the upper meter of the snowpack. With little overnight re-freeze the warm temperatures will penetrate deeper allowing melt and a lot of water which will lubricate the upper snowpack. It also allows the upper snowpack to start creeping downhill at an accelerated rate. Its hard to say how many hot days and warm nights it will it take to wake up the more deeply buried weak layers. We're not sure, but now is probably a time to let the mountains do their thing from afar and check back in when the freezing levels return to seasonal norms which could happen by next weekend.
swerner,
Avalanche Canada
