Avalanche Forecast
Issued: Jan 18th, 2019 4:52PM
The alpine rating is Storm Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeStorm slabs are gradually building above a touchy weak layer. Be extra cautious around steep rolls and wind loaded slopes.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
FRIDAY NIGHT: 5-10 cm of snow, moderate southwest wind, alpine temperatures drop to -5 C.SATURDAY: Scattered flurries with another 5-10 cm of snow, strong southwest wind, freezing level climbing to 1300 m, alpine high temperatures around -3 C.SUNDAY: Mostly cloudy with flurries possible later in the day, strong west wind easing throughout the day, freezing level climbing to 1000 m, alpine high temperatures around -6 C.MONDAY: Skies clearing throughout the day, light to moderate north wind, alpine high temperatures around -6 C.
Avalanche Summary
Small slab avalanches were reported in the top 10-15 cm of new snow on Friday and Thursday. Slab avalanches will become more likely as snow accumulates above the freshly buried weak layer. The key is watching for signs of this new slab becoming reactive, such as cracking, whumpfing, or stiffer deeper pockets of snow.Two large snowmobile triggered avalanches were reported last weekend. One was triggered on a thin, rocky, southwest facing feature near ridgecrest north of Fernie (see here for report). The other was triggered on a wind affected south facing slope at treeline in the Corbin area (see here for report). Deep persistent slab activity this season has been most common in parts of the region with shallow snowpacks (e.g. near the continental divide) and on alpine features with thin variable snowpack depths.
Snowpack Summary
By Saturday, 15-25 cm of snow will have buried a layer of large surface hoar crystals and sun crusts. This will create the potential for fast moving sluffs and/or thin slab avalanches with wide propagations. The most suspect terrain features will be steep slopes and rolls below 2000 m (where the largest surface hoar exists) and steep south-facing slopes in the alpine (where sun crusts exist).In shallow snowpack areas, the base of the snowpack may still be composed of weak faceted grains. In deeper snowpack areas, the middle and lower portions of the snowpack are generally considered to be well-settled and strong.
Problems
Storm Slabs
New snow is gradually accumulating above weak surface hoar and/or crusts. Touchy slabs can be expected in areas with more than 20 cm of new snow, such as wind loaded slopes.
Watch for signs of instability such as whumpfing, or cracking. Avoid shallow rocky areas where triggering deeper layers is more likely.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 19th, 2019 2:00PM