Yesterday we received a report of another cornice fall in Warm-up Bowl possibly triggered by someone walking on the ridge. Sunday night we received multiple reports of cornice falls being triggered that day. Remember to give cornices a wide berth on the ridge as they can break off further back than expected and potentially take you for a nasty ride. They could also trigger a wind slab or larger avalanche below, creating an even bigger problem. It is also important to limit exposure time below them especially with so many people out enjoying the snow this holiday week. There is snow in the forecast today and increasing winds. This will decrease visibility and make it harder to determine where you are in relation to the cornices.
If snow amounts are higher than forecast watch for storm slabs forming today. There is weak snow on the surface and the new snow may not bond well to the old.
WIND SLABS: Winds are forecast to increase today. Any new snow falling may easily get blown into start zones and begin to form tender wind slabs. In addition, Saturday’s sustained NE winds that were strong enough to move snow around and form cornices also potentially created wind slabs on steep, unsupported slopes. Yesterday there were reports cornice falls triggering small pockets of wind slab. Continue to be on the lookout for these today. At this point the older wind slabs may be quite stubborn and could allow a person well out onto them before releasing. Watch for shooting cracks, hollow sounding snow and be especially aware of the terrain – if a wind slab or cornice does release where will you go?
Dog triggered cornice fall on December 23rd. Photo: Andy Moderow 12-24-18
Magnum ridge cornice, 12-24-18. Photo: Andy Moderow.
Buried weak layers roughly 2′ below the snow surface have been found in areas south of Turnagain Pass in both the Summit Lake zone and as far south as Lost Lake. We suspect the snowpack may be similar around Johnson Pass, Lynx drainage and Twin Peaks/Silver Tip. These weak layers are composed of facets associated with crusts and have been showing signs they could be reactive enough a person could trigger a large avalanche. If you are headed to areas south of Turnagain, keep in mind triggering a large slab avalanche is possible. Listen and feel for whumpfing (collapsing of the snowpack) and look for avalanche activity from the storm that may have steeped down into the deeper layers.
Yesterday two recent glide avalanches were observed in the Lynx Creek drainage along with multiple opening cracks. Observers reported the glide cracks on Sunburst and in Warm-up (-1) Bowl are opening and continue to see new glide cracks throughout the advisory area. It is important to remember glide avalanches can release at any time and are not associated with human triggers. Limit travel underneath. It’s a case of not wanting to be in the wrong place at the wrong time.
Recent glide avalanches in Lynx Creek,12-24-18. Photo: Andy Moderow
Cornice fall and glide gracks on Sunburst, 12-24-18. Photo: Andy Moderow
Yesterday: Skies were mostly clear with some valley fog. Temperatures were in the teens and 20Fs with some valley bottoms hitting single digits. Winds were light. Clouds moved in overnight and temperatures are slowly rising.
Today: Mostly cloudy skies with snow showers throughout the day, 1-7″ is forecast. Winds will be easterly 15-30 mph gusting into the 40s. Temperatures will be in the 20Fs to low 30Fs. Snow showers and gusty winds continue overnight.
Tomorrow: There is a chance of snow throughout the day with mostly cloudy skies, calm winds and temperatures in the 20Fs to low 30Fs. The overall weather pattern is forecast to be active at the end of the week into the weekend. Fingers crossed for a snowy 2019! #snowtosealevel
*Seattle Ridge weather station was heavily rimed and the anemometer (wind sensor) was destroyed.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||24||0||0||58|
|Summit Lake (1400′)||12||0||0||12|
|Alyeska Mid (1700′)||25||0||0||32|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||23||*N/A||*N/A||*N/A|