Today’s primary concern will focus on the increase in winds from overnight and the strong winds forecast for today. There is just enough loose snow available for transport that fresh wind slabs are likely to form along ridgelines and other exposed slopes. Watching for the usual suspects such as cracking in the snow, stiff snow over softer snow, and smooth wind loaded surfaces will be key. Cornices are also something to keep in mind and continue giving a wide berth to.
Ok, now to the impending change in weather and increase in avalanche danger for tomorrow: With a potent storm system at the doorstep, we are taking stock of not only how much snow will fall this weekend (up to a foot or more by tomorrow), but what types of surfaces it will fall on to. For those that have been enjoying the sunny days on Turnagain Pass last week, you will know that variable snow surfaces exist. These are: sun crusts on Southerly slopes, wind crusts on various aspects at all elevations and ridgelines and last, an abundance of soft loose faceting snow. On top of all these surfaces sits a layer of surface hoar that is anywhere from a few mm in size up to 2cm in places. What this all means is, any new snow that falls will fall on a weak layer of some type, limiting bonding between the new and old snow. In some areas, like South aspects, there will be a crust under the weak layer making bonding even more difficult. The good news is, we have strong winds today ahead of the snow which can blow over the surface hoar and generally make this set up less scary. But, this is not a sure bet and time will have to tell.
Surface conditions as seen yesterday along Seattle Ridge:
1-2cm surface hoar on top of Seattle Ridge 1-2cm sun crust with 3mm surface hoar on Southerly slopes
We did not see, or have any reports, of any glide cracks that released yesterday. That said, it’s the year to know where these cracks are and limit time under them as they can release with no warning.
Photo: Graham Predeger looks over at a large glide crack on the West side of Main Bowl (1st Bowl).
High clouds filtered over the region yesterday ahead of storm slated to move in this evening. During the past 24-hours winds have picked up slightly from the East along the ridgetops to the 10-20mph range and temperatures are holding steady, ~20F in the Alpine and ~30F at 1,000′.
Today we should see mostly cloudy skies with winds increasing into the 25-35mph range from a generally East direction. These winds should be the main player in weather considering snowfall is not expected to begin in earnest till the afternoon. Once snowfall does begin, we could see up to 5″ of snow by this evening (.5″ of water equivalent) and another 5-10″ (~1″ water equivalent) by Sunday morning. The rain/snow line looks to be around sea level today then possibly raise as high as 1,000′ tonight.
For Sunday, the main storm system looks to move out rather quickly but lingering instability showers and decreasing winds could add several inches of quality snow to the area. Temperatures look remain cold enough for snow to 1,000′ for the duration of the storm. Stay tuned on tomorrow’s advisory!
The Seattle Ridge weather station is back up with wind information – finally!!
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||26||0||0||101|
|Summit Lake (1400′)||24||0||0||30|
|Alyeska Mid (1700′)||28||0||0||85|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||20||SE||17||39|
|04/21/21||Turnagain||Observation: Sunburst||Schauer/ Behney Forecaster|
|04/19/21||Turnagain||Avalanche: Triangle, Seattle creek||Will Morrison|
|04/18/21||Turnagain||Avalanche: Turnagain Pass Road Obs||Andy Moderow|
|04/18/21||Turnagain||Observation: Seattle Ridge, approximately 300 yards south of the up track||Brent Byrne|
|04/17/21||Turnagain||Avalanche: Road obs||Johnston-Bloom / Moderow Forecaster|
|04/16/21||Turnagain||Avalanche: Seattle Ridge||Wendy Wagner Forecaster|
|04/16/21||Turnagain||Avalanche: Turnagain Pass, non-motorized side seen from Seattle Ridge||CNFAIC Staff Forecaster|
|04/16/21||Turnagain||Observation: Sunburst||Lance breeding|
|04/15/21||Turnagain||Observation: Tincan||Schauer/ Rothman Forecaster|
|04/13/21||Turnagain||Observation: Turnagain Pass Road Obs||A Schauer Forecaster|
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: firstname.lastname@example.org
|Area||Status||Weather & Riding Conditions|
This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.