Register for an account and never miss a forecast again!
RegisterRegister for an account and never miss a forecast again!
RegisterMar 19th, 2018–Mar 20th, 2018
.
Low Danger does not mean no danger. Continue to use normal travel practices. Deep Persistent Slab avalanches are very difficult to trigger, but the potential for high consequences lurks deep in the snowpack. Weak layers buried deep in old snow have been responsible for fatalities and serious injuries over the past month.
Low Danger means that triggering avalanches is unlikely but not impossible. While Deep Persistent Slabs are very difficult to trigger, the resulting avalanche could leave little chance of survival. Persistent weak layers have been the cause of avalanche fatalities or serious injuries every weekend for the past 4 weeks. Recent test results and avalanches show that these layers are still present, though getting harder to trigger. The best way to stay safe from the potential consequences is to limit your exposure to large avalanche paths. Stay out of start zones and large, complex avalanche paths.
You may see roller balls and small Loose Wet avalanches running on steep sunny slopes near rocks and trees. Until solar exposed slopes get softened by the sun they will remain hard and slick. It may be difficult to stop a fall on these slopes while they are still firm. Avoid traveling near or under areas with glide cracks and stay away from large cornices.
Expect warming temperatures and sun for Tuesday. While there may be some roller balls or small point releases, Loose Wet avalanches should not pose significant hazard. A dusting of light snow on Saturday and Sunday followed a warm, sunny stretch at the end of the work-week. Many sunny slopes have stout crusts in the top foot of the snowpack. At Mt. Baker, 6 inches of snow accumulated Wednesday, which quickly melted on sunny slopes. Mid to upper elevation, northerly slopes are staying soft and dry.
Below this most recent crust most observations indicate strong layers of dry snow intermixed with various melt freeze crusts. A more widespread deep persistent layer continues to be found 5-7 feet below the snow surface in the Mt. Baker zone. A thin layer of weak sugary facets have been observed just above a stout crust (2/8) on some aspects. Some snowpack tests (Compression Test and Extended Column Tests) will not be able to appropriately assess this deep weak layer. Deep Tap tests and Propagation Saw tests will yield the most reliable results. While snowpack tests are good for demonstrating the presence of a weak layer, they are not a decision-making tool to determining whether or not a slope is safe.
Observations
Baker
On Saturday, NWAC Observer Matt Primomo reported a large glide avalanche on a rock face on the south aspect of Mt Herman. The slope is known to commonly produce glide avalanches during warm conditions.
NWAC professional observer Lee Lazzara traveled to Ptarmigan Ridge Friday. New and recent wet loose avalanches, generally small, were visible on steep sunny slopes. Older wind slab found near and above treeline was unreactive. A thin sun crust from Thursday had extended it's reach to W-NW aspects. The 2/8 layer was down 6 feet in this area.
Lee was near Glacier Creek Thursday and found 3 to 8 inches of new snow well bonded to a forming melt-freeze crust. The 2/8 layer was down 6 feet in this area.