Avalanche Forecast

Issued: Nov 23rd, 2014 7:40AM

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

Avalanche Canada Peter, Avalanche Canada

Incoming storms will bring more snow up high, which could overload recently buried weak layers in the snowpack. It might be best to ease into the season with lower risk objectives.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Overview: A series of strong frontal systems are forecast to cross the province early this week bringing mild and wet conditions to most areas. The Columbia Mountains should expect moderate to locally heavy precipitation each day this period with the freezing level hovering between 1000 and 1500 m.Monday:10-20 cm; freezing level near 1400 m; Ridge winds are moderate to strong from the SW.Tuesday:10-20 cm; freezing level near 1400 m; Ridge winds are moderate from the W.Wednesday: Continued moderate precipitation; pretty uncertain about temps could cool a bit in a NW flow or could rise with the weather system.

Avalanche Summary

A relatively small natural avalanche cycle was reported in Glacier National Park on Saturday. Observers noted several slides up to size 2, but visibility was limited. It's likely other parts of the region saw similar avalanche activity. Given the weather forecast, I would not be surprised if we saw more widespread avalanche activity at some point early this week.

Snowpack Summary

This is an estimate of what the snowpack may look like based of a few observations and previous weather. If you plan on riding in avalanche terrain be sure to supplement this with your own observations and please pass along any data you collect (forecaster@avalanche.ca)Around 30-40 cm of new snow sits on a layer of surface hoar and/or a sun crust on southerly slopes. Below this is 20-30 cm of old snow, which is probably quite weak and facetted (sugary). A thick rain crust which formed a few weeks ago is now down 50-80 cm. The average snowpack depth in the alpine is around 100-120 cm. Recent strong and variable winds have probably created dense wind slabs in exposed terrain and resulted in variable snow distribution. At lower elevations expect travel to be difficult and potentially hazardous as many early season hazards are exposed or lightly buried (stumps, logs, rocks, open creeks, etc).

Problems

Storm Slabs

An icon showing Storm Slabs
New snow on Monday could overload weak layers beneath producing natural avalanches. Expect deep and dense wind slabs to form in exposed lee slopes and cross-loaded features.
Avoid freshly wind loaded features.>Be alert to conditions that change with elevation.>Choose conservative lines and watch for clues of instability.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Valid until: Nov 24th, 2014 2:00PM