East Slopes South

Heavy rain on a troubled snowpack will make for a very dangerous day across the East-South. Any slope that has not produced an avalanche yet could on Wednesday. Avoid travel below big, steep slopes, cornices, cliffs, and rocky terrain covered in snow.

The eastern cascades will see an impressive amount of rain over the next 24 hours. You’ll likely encounter the heaviest precipitation from Darland Mountain south. The forecast team thinks most areas with a shallower snowpack have probably produced avalanches, but we’re more concerned about those locations with a deeper snowpack for Wednesday that have yet to. These areas, like Darland Mountain or the east side of Mt Adams, hold a deeper snowpack with of old, weak layers lurking 3-4 ft below the surface. Once water percolates to these layers, watch out - we could see some very large avalanches. 

On Sunday, NWAC forecasters traveled into the S. Fork Manatash Creek Drainage and found widespread evidence of the recent warming and subsequent wet avalanche cycle. Wet loose avalanches were widespread, and they found an older slab avalanche that likely ran on a persistent weak layer earlier this month. A snow profile at 6200ft on a northerly aspect revealed a mostly dry snowpack. Although evidence of pooling on lower interfaces means drainage channels had formed, this only allows water impact and weaken a layer of faceted snow and surface hoar above the Solstice Crust. This problematic layer showed a likelihood for propagation in a snowpack test and has been the layer involved in widespread wet slab avalanches throughout East Central and East South. This is a good reminder that the prolonged warming has only prolonged the instability of these weak layers. Human-triggered large to very large wet slabs at Mission Ridge and near Stevens Pass are indications that even as natural avalanche activity decreases, you can still trigger one of these destructive avalanches. 

If you get out, let us know what you see by submitting a public observation!