Avalanche Canada mgrist, Avalanche Canada

South Rockies Avalanche Forecast

Mar 16th, 2018 4:45PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Storm Slabs and Loose Wet.

Recent precipitation fell as snow at higher elevations and a mix of snow and rain at lower elevations.  Watch for signs of instability, such as cracking, whumpfing, and avalanche activity -- each elevation band will be different.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Saturday

Weather Forecast

We're looking at seasonal temperatures and generally light snowfall accumulations in a north / easterly flow pattern. The very north of the region may see 10-15cm snow through Saturday. SATURDAY: Cloudy with light snowfall, accumulation 5-10 cm with more possible in northern sections of the region, light northeasterly winds, alpine temperature -1 C, freezing level 1500 m.SUNDAY: Cloudy with light snowfall, accumulation 5 to 10 cm, light to moderate northerly winds, alpine temperature -3 C, freezing level 1100 m.MONDAY: Cloudy with isolated flurries, moderate westerly winds, alpine temperature +1 C, freezing level rising to 1600 m.

Avalanche Summary

Many wet loose and dry loose avalanches to size 1.5 were reported on sunny aspects on Friday. Isolated natural storm slab activity to size 2 was also noted on east facing fan features, likely running during Thursday's storm.

Snowpack Summary

Around 20 to 30 mm of water equivalent fell in the region on Thursday into Friday. This would have fallen as snow at higher elevations (up to 25 cm of snow) and partially as rain at low elevations. This precipitation fell on a thick melt-freeze crust that exists on all aspects from recent warm temperatures and rain, except for possibly higher elevations on north aspects. The upper snowpack may still be wet at low elevations.A weak layer of surface hoar buried mid-February exists in parts of the region around 50 to 80 cm deep. The lower snowpack is weak with a combination of crusts and facets near the bottom of the snowpack that are widespread.

Problems

Storm Slabs

An icon showing Storm Slabs

Likelihood

Likely - Possible

Expected Size

1 - 2
Around 15 to 25 cm of snow fell at higher elevations in the region, with north west winds. Watch for signs of poor bonding of the new snow with underlying surfaces.
Use caution in lee areas in the alpine and tree line, especially east facing slopes.Observe for signs of instability, such as cracking, whumpfing, and avalanche activity.Keep an eye out for localized areas of deeper snow accumulation, particularly on eastern slopes.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Loose Wet

An icon showing Loose Wet

Likelihood

Likely - Possible

Expected Size

1 - 2
High freezing levels and recent rain have moistened the snowpack at lower elevations. Use caution in terrain features where a small avalanche could have serious consequences.
Avoid terrain traps such as gullies and cliffs where small avalanches can have high consequence.Watch for signs that the snow is moistening such as pin-wheeling and point-releases below cliffs.

Aspects:

North, North East, East, South East, South.

Elevations:

Alpine.

Valid until: Mar 17th, 2018 2:00PM