Archived

Avalanche Forecast

Mar 17th, 2018–Mar 18th, 2018

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

1: Low

The avalanche danger rating in the alpine will be low

Treeline

1: Low

The avalanche danger rating at treeline will be low

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Rockies.

There is significant uncertainty with forecast snowfall amounts on Sunday. Watch for signs of instability, such as cracking, whumpfing, and avalanche activity at higher elevations.

Confidence

Low - Timing, track, or intensity of incoming weather system is uncertain on Sunday

Weather Forecast

Significant uncertainty exists with the formation of the weather-making lows in Alberta and Montana. Precipitation totals of 5mm for Sunday are most likely, but 10mm + could be possible as well. SUNDAY: Cloudy in the morning; light snowfall late in the day (accumulation 5 to 10 cm). Light northerly winds. Alpine temperature -1 C. Freezing level 1400 m.MONDAY: Cloudy with isolated flurries. Moderate westerly winds. Alpine temperature +1 C. Freezing level rising to 1600 m.TUESDAY: Cloudy with sunny breaks. Light westerly winds. Alpine temperature +2 C. Freezing level 1700 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. See this MIN post for more information.

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. Sunny conditions on Friday (and some locations on Saturday as well) created moist surface snow on sunny aspects, which froze to form a 2-5 cm thick crust overnight. 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.

Avalanche Problems

Storm Slabs

Watch for signs of poor bonding of the new snow with underlying surfaces, especially the March 15th crust, which can be found almost everywhere except high north facing aspects.

Keep an eye out for localized areas of deeper snow accumulation, particularly on eastern slopes.Observe for signs of instability, such as cracking, whumpfing, and avalanche activity.Use caution in lee areas in the alpine and tree line, especially east facing slopes.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 2