After enjoying sunny skies and a mostly stable snowpack a series of storms will begin to affect the advisory area today. Temperatures are on the rise, winds are increasing and precipitation will start to fall later in the day. Today is the day to expect changing conditions and be on the lookout for signs of instability. Initially increasing winds may trigger small loose snow avalanches but as they continue and intensify, wind slabs will build in exposed terrain. There is soft snow available for transport and wind slabs may be quite tender as they develop over very weak surface snow formed during the cold weather. Well developed surface hoar was observed at lower elevations and along some ridge tops. Near-surface faceted snow was observed at all elevations. Below 1500′ there is a crust below the weak snow. This is not a good set-up for new snow and wind-loading. Look for blowing snow, cracking, collapsing and be especially heads-up if natural wind slabs start releasing.
Rapidly warming temperatures and the additional blowing snow may also make cornices easy to trigger over the next few days. As always, give these a wide berth.
Weak surface and just below the surface snow on Center Ridge, 1-10-19.
Weak surface snow on the Gold Pan ridge, 1-11-19. Photo: Allen Dahl
South of Turnagain – Lynx Creek/Johnson Pass/Summit Lake zone: As the weather pattern changes and the potential for wind loading increases it becomes even more critical to remember that a poor snowpack structure exists in these areas. The Christmas buried surface hoar has been found as well as concerning facet/crust combinations in the bottom of the snowpack. Avalanches may initiate near the ground and be quite dangerous. If you’re headed this way, evaluate terrain exposure and the snowpack as you travel. Be on the lookout for signs of instability.
Identify glide cracks and avoid spending any time under these features. Glide cracks are opening and have avalanched within the last week. Glides are completely unpredictable and not human triggered. The rapid temperature rise and additional snow load over the next few days may or may not cause an increase in glide activity.
Yesterday: Skies were clear and temperatures were cold with daytime highs in the single digits. Valley bottoms remained below zero. Winds were light and easterly. Overnight clouds bulit and temperatures began to increase.
Today: Mostly cloudy skies with an increasing chance of precipitation throughout the day. Temperatures will continue to rise into the 20Fs. Easterly winds will build and blow 15-25 mph with gusts into the 40s. These are forecast to increase overnight. Snowfall will increase overnight and temperatures will rise with the potential for rain to fall at sea level.
Tomorrow: Cloudy skies and snow continues tomorrow with the brunt of the storm in the early morning. Winds will remain strong and temperatures will continue to rise with the warmest temperatures on tap for Monday. The series of fronts and lows are forecast to impact the region into the week.
*Seattle Ridge weather station was heavily rimed and the anemometer (wind sensor) was destroyed. We are currently working to replace it.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||6||0||0||53|
|Summit Lake (1400′)||-1||0||0||20|
|Alyeska Mid (1700′)||8||0||0||41|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||8||*N/A||*N/A||*N/A|