Avalanche Forecast

Fair - Intensity of incoming weather systems is uncertain

A warm, wet storm is expected to carry through from Friday night into Saturday morning. Friday night is expected to see 15-20 mm snow or rain, with freezing levels between 1500 and 2000 m. Saturday: during the day it looks as though there will be a brief clearing, before the next storm starts again in the afternoon. A further 5-10 mm is expected by the end of Saturday with freezing levels around 2400 m. Sunday: a further 10-20 mm is expected, with freezing levels remaining around 2400 m. Very strong southwest winds expected througout the period.

Forecast snow, rain, warm temperatures and high winds are a recipe for an avalanche cycle, especially when you throw in a couple of prominent weak layers. I anticipate an active cycle this weekend. Previous avalanche activity during and after the last storm system was widespread, with avalanches releasing up to size 3 on a variety of aspects and elevations.

Moist new snow and rain forecast for this weekend will fall on a moderately dense upper snowpack. A weak layer that comprises feathery surface hoar crystals up to 15 mm lies buried between 40 and 60 cm below the surface, and may sit above a crust, particularly on south-facing slopes. This "mid-January" weak layer is widespread and has been the main focus for recent avalanche activity and I anticipate it to be active through the weekend as it is loaded by new snow and rain.The still problematic mid-December surface hoar/crust layer is now buried anywhere from 60 to 110cm below the surface and continues to produce clean shears at and below treeline. Avalanches were reported to have stepped down to this layer during and after the most recent storm cycle. With additional loading and warm temperatures, I'd continue to treat this layer with respect and suspicion, particularly in the 1700-1900 m elevation band. A release on this layer would have very high consequences.