Avalanche Forecast

Moderate - Timing of incoming weather systems is uncertain on Tuesday

Tuesday: 10-30cm of new snow / Strong to extreme southerly winds / Freezing level at 1000mWednesday: 25-45cm of new snow / Strong southerly winds / Freezing level at 1100mThursday: 10-25cm of new snow / Moderate southerly winds / Freezing level at 800m

An impressive natural storm slab avalanche cycle occurred in response to new snow and wind on Monday. In some of the big east-facing terrain to the west of the Upper Lillooet Valley, evidence of natural activity to size 4 was observed, while explosives control produced storm slabs in the size 1.5-3.5 range.Looking forward, forecast snow and wind will promote ongoing surface storm slab avalanche activity, while surprisingly deep releases within (or at the base of all of the recent storm) snow may be possible in isolated terrain.

The region has been pummeled by heavy snowfall and extreme southerly winds. By Monday morning the 48 hour snowfall totals were just over 100cm. Thanks to extreme southeast winds, I would anticipate extensive scouring and redistribution of the recent storm snow at all elevation bands with dense storm slabs lurking in lee and cross-loaded features. Impressive cornice growth is also expected to have occurred.About 150cm below the surface you'll find a crust that was buried mid-January and is present at all elevations. This crust is thin on northerly aspects and up to 3 cm thick on solar aspects. Most reports suggest an improving bond at this interface, but the load of the new snow may tip the balance and reactivate this layer in isolated terrain. Below this, the snowpack is generally strong and well-settled.