It's hard to predict exactly how the snowpack will react to the forecasted rain and heat, followed by the extremely rapid passage of a cold front on Thursday morning. One thing is certain: avalanches won't be the only danger in the mountains on Thursday.
The heavy rain on Wednesday night will weaken the surface snow in areas sheltered from the wind, and produce wet loose avalanches on steep slopes. The problem should ease as the snowpack gradually refreezes.
In places where there were recent wind slabs, heavy rain could undo the cohesive bonds between the slabs and the old surface, producing avalanches of wet slabs.
No new avalanches reported or observed.
If you go into the backcountry, thanks for sharing your observations on the Mountain Information Network (MIN).
The thaw and rain will have greatly humidified and affected the height of the snowpack on Thursday morning. With the expected cold front, we can expect a significant refreezing crust to form progressively over the course of the day.
Prior to the passage of this low-pressure system, a multitude of old, very hard wind slabs were to be found in the Alpine region and in wind-affected areas. These slabs rest either on very hard surfaces or on a fragile layer of facetted grains.
The middle of the snowpack is well consolidated, resting on the December 30 combo of flat-faced grains and crust. Flat-faced grains and depth hoar are developping at the base of the snowpack.
Synopsis: The rain and heat brought by the massive Great Lakes low will be followed by a major cold front that will rapidly drop temperatures on Thursday morning.
Wednesday evening and night: Occasionally heavy rain 20-30 mm. Southwest wind 60-90 km/h. High +3. Freezing level at 2500m.
Thursday: Snow early morning then cloudy. 3 to 6 cm. Wind northwest 40 to 70 km/h. Temperatures dropping rapidly to -20C.
Friday: Sunny. Wind northwest 40 to 50 km/h. Maximum -18C.
Saturday: Alternating sun and clouds. Wind southwest 20 to 40 km/h. High -2. Freezing level at 500m.
For more details, check out the most recent alpine weather forecast.
