Avalanche Forecast
Issued: Mar 22nd, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Persistent Slabs and Loose Wet.
LP,
Avalanche Canada
A stronger and deeper snowpack exists in the Yoho zone. Remain watchful for daytime heating and exposure to large triggers above slopes, such as cornices.
Summary
Confidence
Avalanche Summary
On Wednesday, only loose snow avalanches to size 2 were reported by field teams and ski hill snow safety teams. On Tuesday, there was a deep persistent slab reported on Observation peak and Sunshine patrol reported observing two size 2.5 deep slabs in the surrounding backcountry. One on Fatigue Mountain and one near Mt. Ball. Also on Tuesday, Lake Louise patrol reported triggering two old hard wind slabs size 1.5 in the White Horn gullies with explosives.
No other avalanches were observed or reported.
Snowpack Summary
Above 1600 m the surface is 10-25 cm of soft, settled snow with minimal wind effect. Suncrusts are forming on steep solar slopes and are more widespread below 1400 m. The middle of the snowpack holds several crust layers that continue to produce avalanches, and the base of the snowpack is weak facets that appear their strongest in deep snowpacks such as in Little Yoho.
Weather Summary
Thursday - will start clear with cloud building in the afternoon. We may see more solar induced avalanche activity, but it will depend on the incoming cloud an how warm it gets. Overall expect a cooler day (alpine highs of -4C) and westerly ridge top winds of 20-30 km/hr.
Friday - scattered flurries becoming more widespread in the afternoon, but only trace amounts are expected. Winds will generally be light westerly 10-20 km/hr. Overnight, along the eastern slopes, we may see up to 15 cm by Saturday morning, but there is variation between weather models, and we may not see that much.
Saturday - another upslope flow with another 5-10 cm possible on the Eastern slopes by Sunday.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Problems
Deep Persistent Slabs
The weak depth hoar at the bottom of the snowpack inspires little confidence. We have seen increased activity on this layer through the week in most areas of the forecast region with the exception of the deeper snowpack areas around Little Yoho. Give careful consideration to the slopes overhead as large avalanches may run well into the runout zone or into lower-angle terrain. Avoid big terrain features and be especially cautious in thin or rocky areas, where triggering is more likely.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Three persistent weak layers formed in January are down 60-120 cm. Buried sun crusts on steep solar slopes present the greatest concern for triggering, however, weak facets and isolated surface hoar can be found on the same interfaces on shaded aspects.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Wet
Clear skies and sunshine may produce wet avalanches on sun-exposed slopes. This will depend on the timing and extent of the afternoon cloud buildup which may keep surfaces cool versus direct solar warming associated with clearer skies. Rocky areas often increase this heating and low elevations may also be susceptible to this problem with prolonged sun exposure and heating.
Aspects: South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 23rd, 2023 4:00PM
