Avalanche Forecast
Issued: Mar 15th, 2021 3:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Persistent Slabs and Cornices.
jcoulter,
Avalanche Canada
Avalanche hazard will rise with daytime warming and solar input. Time your day to move off slopes before they get moist or slushy. Consecutive days in a row of warm temperatures may increase the reactivity of deeper weak layers and cornices.
Summary
Confidence
Weather Forecast
MONDAY NIGHT: Decreasing cloud, trace precipitation possible, light to moderate south west wind, alpine low -4 C, freezing level dropping to valley bottom overnight in most parts of the region.
TUESDAY: Mostly sunny, light to moderate west wind, alpine high +3 C, freezing level 2100 m.
WEDNESDAY: Mostly sunny, light to moderate west wind, alpine high +2 C, freezing level 2200 m.
THURSDAY: Mostly sunny, light to moderate southerly wind, alpine high +2, freezing level 2200 m.
Avalanche Summary
There were wet loose avalanches size 1-2 from south and west facing alpine terrain reported over the weekend.
Snowpack Summary
Wind slabs in the alpine may linger, especially on northerly aspects. Snow on all solar aspects and elevation bands has been getting moist by mid morning and may not be getting a solid overnight re-freeze if there are some lingering clouds overnight. Reports suggest snow on northerly terrain above 1500 m has so far remained dry. Cornices are large and looming, and glide cracks are increasing in size...both should be considered unpredictable and given a wide berth.
Around 30 to 60 cm of snow sits above a persistent weak layer of sugary faceted grains that was buried in mid-February. There have been a handful of avalanches that released on this layer in the past few weeks. There is another persistent weak layer that was buried at the end of January, found around 50 to 80 cm deep. This layer consists of feathery surface hoar, facets, and/or a hard melt-freeze crust. Periodic avalanches continue to be triggered on these layers by riders, particularly where a stiff wind slab sits above them. Check out this MIN that shows the positioning of the layers in the snowpack near Crowsnest Pass.
Weak faceted snow and a decomposing melt-freeze crust can be found near the base of the snowpack.
Terrain and Travel
- Be alert to conditions that change with aspect and elevation.
- Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
- Use caution on large alpine slopes, especially around thin areas that may propagate to deeper instabilities.
- Cornices become weak with daytime heating or solar exposure.
Problems
Loose Wet
Sun and warm daytime temperatures can quickly destabilize solar slopes and increase the likelihood of avalanches. Things will deteriorate even faster if we don't get a good overnight re-freeze. Pinwheeling and a moist snow surface are signs that the stability of the upper snowpack is decreasing.
Even small avalanches can be a hazard in high consequence terrain and above terrain traps, and wet loose avalanches may trigger slabs where persistent layers still linger.
Aspects: South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Consecutive days of warm temperatures may reactivate persistent weak layers from January and February. Widespread avalanche activity has already occurred on the layers, but they could still be triggered anywhere they haven't already failed. Look for signs of instability and continue treating the snowpack as suspect if you are uncertain whether the layer is still present in your riding area.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornices are large and likely weakening with sun and significant daytime heating. Big cornice falls are a hazard on their own but can also trigger large persistent slab avalanches on the slopes below.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 16th, 2021 4:00PM
