Avalanche Forecast

The WA Cascades will be between storms Thursday and the next system should move inland to have the greatest effect on the southern zones and mainly Mt Hood and south later Thursday and Thursday night. Only light amounts of new snow are expected in the north and central areas with gradually more storm snow in the south later Thursday and Thursday night at cool temperatures. 

The cool weather, expected light winds and precipitation holding off during the day, should allow for a further slow decrease in the avalanche danger through the day Thursday. 

Remain cautious, however, in steeper terrain giving storm instabilities time to settle. Look for wind slab mainly on lee NW-SE aspects near and above treeline. Watch for signs of firmer wind transported snow that can indicate wind slab layers near and below ridges.

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 that was later buried by light snowfall Jan 3rd-4th. Several small avalanches occurred on the Jan 3rd layer last week. Snowpack observations and tests along the west slopes indicate that this layer is no longer present or generally unreactive in snowpack tests. This could still be a layer of concern in isolated and sheltered locations near the Cascade Passes where offshore flow (east winds) has kept temperatures cooler and skies cloudier versus elsewhere along the west slopes, though observer Ian Nicholson searched sheltered areas extensively around Skyline Ridge, Stevens Pass, up to about 5000 feet Wednesday and found no buried surface hoar. In general, Ian found minimal storm slab conditions in that area with mostly settling storm snow with only a thin denser layer formed during warming Wednesday morning, but this was non-reactive in tests or in ski tests.  

Ian was on the S-SW slopes of Litchenburg Mt (Stevens Pass area) Tuesday and found a generally right-side up top portion of the snowpack with no layers of concern and a very thin (1cm) suncrust under Monday's light snowfall on solar aspects. He also observed light to moderate east winds building shallow wind slab on a SW aspect near tree-line Monday afternoon. Through 4 pm Monday, a few inches of new snow had accumulated with snow levels 4000-4500 ft, except near or below 3000 ft near the Cascade Passes.

Storm and wind slabs were more prevalent in the Mt Baker and Snoqualmie Pass area Wednesday, especially Mt Baker where heavier precipitation fell. A natural cycle was reported Wednesday morning with widespread 1-2 ft 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. Alpental pro patrol reported ski and explosive .5-1 ft slab releases with decent propagation, especially in the mid-mountain region around 4500 ft. These slides corresponded to warming following the frontal passage before cooling improved conditions late Wednesday.