Avalanche Forecast Snoqualmie Pass
Friday 25th January 2019
Forecaster: Josh Hirshberg
The Bottom Line: Expect the warmest temperatures of the winter, so far. Warming, sun, and uncertainty of the snow layers at upper elevations will maintain heightened conditions. If you are heading to higher slopes, use caution on slopes 35 degrees and steeper.
Snow and Avalanche Discussion
The layer of buried surface hoar from January 17 is not as prevalent near Snoqualmie Pass, as it is in the nearby Stevens Pass and East-Central zones. That doesn’t mean it is absent. You would be most likely to find this persistent weak layer 1-2 ft below the snow surface in areas near Stampede Pass, or valleys outside of the main Pass locations.
Sat 26th Jan 14:48 - Robert Hahn
Fri 25th Jan 09:00
Zooming in to current conditions, a storm on January 22-23rd impacted most forecast zones. This weather system changed snow at the surface of the snowpack, drove an avalanche cycle, and tested or changed the latest persistent weak layers. The storm ramped up late on the 22nd in most areas. Intense precipitation (mostly snow) fell by dark with strong wind and warming temperatures. In the early morning hours of the 23rd snow switched to rain at the passes and western zones. Cold air to the east maintained low-density snowfall at most locations well east of the crest. In some areas, especially east of the crest, a new weak layer may have been buried at the January 22nd interface.
At the passes and in the western zones, reported avalanches were generally running either at the new/old snow interface or within the new snow. Observers reported a mix of soft slab, wet loose avalanches from near and below treeline with a few reports of shallow slabs above treeline. As of January 24th observations at upper elevations have been limited in most areas, due to lack of visibility and access.
In the eastern zones at areas like Washington Pass, Icicle Canyon, and the Wenatchee Mountains, some reported slab avalanches were confirmed or suspected to have involved persistent weak layers, notably the January 17th surface hoar/near surface facets. Some widely propagating and/or large avalanches were reported, up to destructive size 3. Wind loading was a factor in many avalanches that released at upper elevations. Observers reported a widespread point releases on steep sunny slopes in the new snow where skies cleared on the 23rd.
2 - 2
Aspects: All aspects.
Elevations: Alpine, Treeline.