A significant storm with heavy precipitation amounts and high freezing levels will result in a major avalanche cycle this week.
Summary
Confidence
Good - -1
Weather Forecast
A punchy, slow moving Pacific frontal system is tracking across this region, bringing wet and windy conditions for Tuesday through Thursday. Precipitation amounts of around 30 mm are anticipated for Tuesday, 40 mm for Wednesday, and 20mm for Thursday. Freezing levels will reach around 2000 m during Tuesday and Wednesday, dropping to around 1000 m on Thursday. Extreme ridgetop winds are predicted to gust to around 130 km/h from the SW Tuesday, to 110 km/h from the S on Wednesday and to 100 km/h from the SW on Thursday.
Avalanche Summary
A few natural size 1-1.5 windslabs were observed in the last 24 hours near Stewart.A natural size 1.5 was observed below treeline near Terrace.
Snowpack Summary
The snow tap is still firmly on in this region, with almost continuous precipitation melding one layer of storm snow into the next. Sunday's storm added a further 45 cm of new snow to the ever increasing total; snow depths are currently at record levels for this time of year. Strong southwest to westerly winds have set up touchy windslabs on lee slopes. Large sensitive cornices exist. Expect further significant wind and storm slab development with the forecast weather.In the mid snowpack, buried surface hoar and a crust-facet combo (which extends up to alpine elevations in the south and to 1000m in the north) have become less of a concern in the Terrace area as test results show that they have gained significant strength. Although the probability of reactivity on these layers has decreased, the nature of any avalanche on these layers would be deep and highly destructive.The lower snowpack is generally well settled and strong.
jfloyer,
Avalanche Canada
