Avalanche Forecast
Issued: Apr 22nd, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Loose Wet.
bchristie,
Avalanche Canada
Start in mellow terrain, and watch how the surface snow is changing through the day. A wet and dynamic storm could bring rapid change to the snowpack.
The biggest concerns are fresh storm slabs in the alpine, and rain soaking any dry snow that remains around treeline.
Summary
Confidence
Avalanche Summary
During this week, storm snow was generally reactive to human traffic as seen in this Mountain Information Network post from the SkyPilot area, and this one from the Brohm ridge area. Both of these avalanches occurred on Thursday.
We expect that similar avalanches could be triggered by riders on Sunday within the new storm snow. Also, significant rain at treeline and below is making wet loose avalanches likely, especially in the morning.
Avoiding cornice exposure is also a good idea, as they are very large and looming at this time of year.
Snowpack Summary
By mid-day Sunday, 20-35 mm of rain will have soaked the surface snow to mountaintops in most of the forecast area. At very high elevations, or in places where it keeps precipitating as the temperature drops, you could find dry snow on the surface. The wind picks up from the southwest on Sunday, which means that in places where dry surface snow remains, deeper and touchier deposits may be found in leeward terrain.
The new rain or snow is falling on 120 cm of settling snow that accumulated over the past week.
The remainder of the snowpack is strong and well-bonded.
Cornices are large and looming at this time of year.
Weather Summary
Saturday Night
Cloudy. Moderate rain, 15-25 mm. Snow/rain line between 1500 and 2000 m. Treeline high 2 °C. Light to moderate southwest ridgetop wind.
Sunday
Cloudy. Light rain/snow, 5-10 mm. Snow/rain line around 1500 m first thing in the morning, cooling as precipitation tapers off. Treeline low around -3°C. Moderate to strong southwest ridgetop wind.
Monday
Low cloud. Light snow/rain overnight, isolated areas of 10 cm of snow. Snow/rain line around 1000 m, warming through the day, treeline high around 0°C. Light northwest ridgetop wind.
Tuesday
Low cloud. No new snow/rain expected. Freezing level rising from 1250 m to 1750 m. Light to moderate west or northwest ridgetop wind.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
- Choose relatively conservative lines and watch for clues of instability.
- Avoid terrain traps where the consequence of any avalanche could be serious.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Storm Slabs
20 to 40 cm of new snow in the alpine by the mid-day on Sunday is building fresh storm slabs. Use caution entering steep terrain features, around ridgecrests, and on convex slopes. Retreat to mellower terrain if you find signs of instability like shooting cracks, or recent avalanches.
Slabs may be deeper and toucher on northerly terrain features at high elevations in wind-exposed terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
The most problematic elevation is likely around treeline, where recent dry snow is getting hit by rain for the first time.
Wet loose avalanches may be less likely at low elevations, where most of the snowpack has already experienced several heavy rainfalls and significant warming, but if you are finding, deep, slushy, loose snow, use extra caution on steep slopes.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Apr 23rd, 2023 4:00PM
