Valid until Wednesday February 15th 2012

Next update Wednesday Feb 15th 2012

Confidence:  Fair. Uncertainty about the intensity, timing and track of coming systems. Watch precipitation amounts particularly on Friday.

Main Concerns: (Avalanche problems)

Wind Slab - With coming precipitation and winds new wind slab will be formed in the alpine and at tree line on north, north east and east slopes on Thursday and also on north west slopes on Friday. These slabs will be triggerable by humans and will produce avalanches from small to large enough to bury, injure or kill a person.

Weather:

The Island Alps saw only light snow showers in a few places since Monday. Winds were generally light. Freezing levels were around 1100  meters though daytime warming saw them going  above tree line and snow getting moistened by sun on solar aspects. The outlook is as follows:

Wednesday: Continued high pressure with no precipitation and light south westerly winds. Freezing level around 1000m .

Thursday: Our first frontal system in some time will bring 10 to 15cm of snow. Winds will be moderate to strong south westerlies dropping to light south westerly with the passage of the front. Freezing levels around 900m.

Friday: Another quick moving front will bring an additional 5 to 20cm of snow (greatest amounts on the west coast). Winds will be moderate to strong south easterlies. Freezing level around 900m.

Snow Pack:

In the Alpine new wind slab will be forming on top of 10 to 20cm of last week ends new snow which in turn sits on a weak crust. Under the crust are moist facets/mixed forms which produce clean shears and Rutschblock 3 scores . Deeper in the snow pack is a stronger crust that delivers shear results in tests but they require hard forces to elicit. The Lower snowpack is strong and well consolidated. At treeline and below treeline two layers of crusts cap off the upper snowpack. The upper crust is breakable and a foot can penetrate from 0 to 25 cm into it depending on elevation and aspect. On cooler aspects if you break the crust it produces propagation cracks and shears easily in unsupported ski cuts. Surface facets and surface hoar have formed in shady, protected areas at tree line and below.

East Island snow packs are about 2.2 m on average at tree line. West Island snowpack are about 3.5 m on average and North Island snow pack is about 2 m on average.

Avalanche Activity:

No new avalanche activity since last report.

Travel Advisory:

Avoid areas of new wind loading on Thursday and Friday. Watch precipitation amounts carefully especially on Friday. If amounts are greater than those forecast above raise the hazard from Moderate to Considerable and increase caution particularly in wind loaded areas. Be aware that with greater snow loads weak layers deeper in the snow pack could be activated making for larger avalanches. Give cornices a wide berth whether you are traveling above or below them.

Prepared by Jan Neuspiel