Avalanche Forecast

A system will move mainly across Oregon and north California on Thursday night. This system should spread some moderate snow as far north as Mt Hood on Thursday night and Friday morning with way less in the Olympics and Washington Cascades.

Some snow showers should drift north over western Washington on Friday. Models vary on whether or not there will be a change to a light west wind  in the Cascade passes but this change will be indicated in the weather forecast along with a bump in the snow level for the central Cascades Friday afternoon. The snow showers should bring mostly light amounts of new snow in the Olympics and Washington Cascades and are not expected to cause a great change in snow conditions along the west slopes.

Avalanche problems should be mainly from layers formed during the snowfall seen about January 12-14th.

Wind slab from January 12-14th should be most likely on ridges and on north to southeast slopes near and above treeline. Watch for signs of hollow snow and firmer wind transported snow.

Storm slab where it might still exist from January 12-14th could linger on more varied aspects but should be becoming unlikely and should be stabilizing.

New wind or storm slab layers would be possible if there is more snow than expected on Friday. Be prepared to adjust your plans if you are out and find more than a few inches of new snow on Friday.

Deep storm snow that fell during mid-late December is well settled, homogeneous and has stabilized, so the focus on the current avalanche danger will be on the upper snowpack and the most recent storm snow.

Fair weather over the New Year caused extensive surface hoar and near surface faceted snow. This was buried by about 4-15 inches of snowfall along the west slopes from about January 3-6th. Several small avalanches occurred on the Jan 3rd layer last week. But the latest observations and tests along the west slopes indicate that this layer is generally no longer present or unreactive in snowpack tests.

Another fair weather period was seen from about January 7-11th. Surface hoar formed in many areas during this period.

The latest period of snowfall has been from about January 12-14th with about 7-20 inches along the west slopes. A cooling trend was seen at the tail end yesterday with a bump in temperatures in the Cascade passes when winds changed from east to west there.

Storm and wind slabs were more prevalent in the Mt Baker and Snoqualmie Pass area Wednesday. A natural cycle at Mt Baker was reported by the Mt Baker pro patrol Wednesday morning with widespread 1-2 foot storm or wind slab releases on steeper north facing slopes near tree line. Some slides caused sympathetic releases running to the valley floor depositing large debris. The Alpental pro patrol reported ski and explosive .5-1 foot slab releases with fair propagation, especially in the mid-mountain region around 4500 feet.

NWAC pro-observer Ian Nicholson was at Stevens Pass on Wednesday and reported mostly right side up snow with snow pit tests giving moderate low quality shears without propagation at about 30 cm down in the lower part of the most recent storm snow. No avalanches were observed. The bump in temperatures did cause a great change in snow conditions.

From a combination of  reports from the Mt Baker pro patrol and the NWAC Observations page, a 2-3 foot wind was remotely triggered today at about 5500 feet on the north side of Shuksan Arm. The report from the Mt Baker pro patrol indicates the interface was the surface hoar that was buried on about January 12th.