Avalanche Forecast

Disagreement between weather models has resulted in a high degree of uncertainty around snowfall amounts. The bulk of the storm will pass Tuesday night with unsettled convective activity following behind, resulting in scattered flurries through the day Wednesday.

Tuesday night: 20-40 cm of new snow in the west of the region with smaller amounts around Terrace. Extreme southwest wind easing to moderate and shifting northwest. Alpine high temperatures around -4. Freezing level 1000 m.

Wednesday: Lingering convective flurries. Moderate west winds. Alpine high temperatures around -4. Freezing level 1000 m.

Thursday: Mix of sun and cloud. Northwest wind increasing to strong. Alpine high temperatures around -7. Freezing level 800 m.

Friday: Mix of sun and cloud. Strong southwest wind. Alpine high temperatures around -3. Freezing level 1000 m.

Reports of avalanche activity on Monday come primarily from the southwest of the region, near the Howson range, including:

• At Shames, a skier accidentally triggered a storm slab size 1.5 on a northwest aspect around 1400 m.
• East of Kitimat, a natural cornice-triggered wind slab size 2 on an east aspect around 1000m. Crown depth ranged from 70 cm up to 2 m. The failure plane is suspected to be a layer of surface hoar buried in early March.
• Along the CN corridor west of Terrace, low elevation loose wet and wet slabs ran naturally size 1.5-2
• Also along the CN corridor west of Terrace, several natural glide slabs were observed size 2-3. This serves as a great reminder to avoid slopes with glide cracks on them at all times. They are inherently unstable and can release at any time.

10-40 cm of new snow is forecast to fall overnight Tuesday amid strong southwest wind, bringing storm totals to 20-60 cm. 50-90 cm below the surface a crust exists on solar aspects and below 1400 m. At higher elevations where this crust tapers out, the new snow has added significant load to a couple of deeply buried weak layers that we haven't quite ruled out as problems.

The first and most concerning is a roughly 70-100 cm-deep persistent weak layer of surface hoar buried March 12 on sheltered northerly aspects around treeline. Deeper down, around 100 to 300 cm now overlies another layer of surface hoar (and faceted snow) buried in mid-February that may still be a concern in shallower snowpack areas. Although they haven't produced recent avalanches, professionals in the region have been tracking and treating these layers with caution. If it hasn't already been occurring, there is a chance further loading during Tuesday's storm could result in some step-down activity to produce very large and destructive avalanches.

The mid and lower snowpack is well settled and strong in most areas.

• Be careful to keep storm day fever from luring you out into bigger terrain features.
• Continue to make conservative terrain choices while the storm snow settles and stabilizes.
• Avoid freshly wind loaded terrain features.
• Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.