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Weekend conditions update — Feb. 19

 | February 19, 2021

Every weekend SPIN will compile the current avalanche forecasts and weather for the Interior. As a reminder, we’ve pulled this information together for a convenient overview to help make your initial plans and recommend reading the full avalanche forecast, and checking and assessing conditions on your own specific to your unique location. Tune in at the end of each week to get the forecast before your weekend adventures begin!

A pair of frontal systems will spike avalanche danger ratings this weekend and Avalanche Canada warns of trouble in the mountains, especially on Sunday.

Extreme amounts of wind and snow mixed with rising temperatures could equate to a natural avalanche cycle Sunday in the Coastal ranges and human triggered avalanches in the Interior zones. Special caution in avalanche terrain and near terrain traps will be required if stepping into the backcountry this weekend.

Weather

The first frontal system will strike the Northwest Coastal ranges Saturday morning before delivering heavy snow to the South Coast Inland and Interior ranges later in the day.

The second and more active frontal systems will arrive Sunday and bring very heavy snowfall amounts, extreme mountaintop winds, and rising temperatures to the South Coast and Interior mountain ranges by the afternoon. The three combined weather events will give rise to dangerous avalanche conditions in most areas throughout B.C.

Wind speeds associated with the pair of frontal systems are expected to be around the 50-80km/h mark for Saturday and increase to 100-120km/h for Sunday. 

Snowfall will accumulate in the 5-10cm range for the Interior and 10-15cm range for the Coquihalla area on Saturday. Meanwhile Sunday is expected to get a dump of up to 50cm in the South Coast Inland zone and up to 15cm in the Interior ranges while other areas inland could receive up to 50cm and other Coastal zones could see up to a metre of snow.

Read the forecasters blog here to find out more about what this means for the snowpack and avalanche terrain travel.

As for Sun Peaks specifically, the Sun Peaks Resort LLP website is calling for only a trace to 2cm for tonight (Friday) and up to 3cm forecasted for Saturday with 40km/h gusts of wind. Temperatures will range from -6C to -11C before warming up to -3C Sunday. 

Avalanche Forecast

The South Coast Inland will see the greatest increase in avalanche danger ratings this weekend as it will receive the most amount of precipitation, wind, and temperature rise when compared to nearby Interior ranges.

Saturday is marked as considerable in the alpine and moderate treeline and below. Sunday will see the danger rating rise to high at treeline and above and considerable below treeline. 

The main issues in the region will be windslabs at treeline and above on all aspects with a possible to likely chance of triggering avalanches up to size 2.5 with the reactive areas being the areas where large amounts of snow have been transported by the wind, typically around ridges and lee slopes.

A secondary avalanche problem is formed by storm slabs treeline and above on all aspects with a possible chance of size 1-2 avalanches. More reactive storm slabs will be found in the south of the region due to slabs that sit atop a melt-freeze crust down 60-80cm in the Coquihalla area but have not been found to be very reactive.

Forecasting confidence is low in the region due to extremely variable snowpack conditions reported throughout the region according to avalanche.ca

The North and South Columbia regions will be forecasted at considerable in the alpine and moderate at treeline and below on Saturday before all elevations move to a considerable danger on Sunday.

This region’s avalanche problems will be associated with wind turning snow into slabs above weak facets and surface hoar layers treeline and above on all aspects with a possible chance of triggering large avalanches depending on snow accumulation amounts.

Persistent slabs are also evident on all elevations and aspects with a possible chance of triggering size 2-3.5 avalanches. This issue is most associated with steep terrain features and the weak layer is composed of either surface hoar, facets, and/or crusts down 60-120cm depending on where you are in the region.

The Cariboos’ danger ratings differ slightly as Saturday’s below treeline forecast is expected to be low while everything else remains the same as the North and South Columbia forecast.

Wind slabs also exist above facets and surface hoar in the region creating a problem treeline and above on northwest, north, northeast, east and southeast aspects. Avalanches are possible to likely and could be up to size two.

Persistent slabs 40-70cm thick are present at all elevations and aspects with a possible chance to trigger up to size 2.5 avalanches. This problem has been most sensitive around treeline.

A large human triggered avalanche was reported in Wells Gray on Wednesday due to conditions created by reverse wind loading, the report of the avalanche can be found here.

To read more details about the forecast visit www.avalanche.ca.

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