#hellowinterwherewereyouinmarch. An active weather pattern starting Thursday April 17th brought snow and rain to the area and total water amounts ranging from 3.6″ at the Alyeska top station, 4+” in Portage, 2.1″ at Center Ridge on Turnagain Pass to 1.1″ in Summit Lake. This equates to upper elevations receiving between 10-40″ of snow favoring Girdwood and Portage. Temperatures cooled Sunday afternoon into Monday and brought light snow to sea level. Sunday there were strong sustained easterly winds that gusted as high as 78 mph on Sunburst. These eased off that evening and were mostly light yesterday. Triggering a 1-3′ slab will be possible on slopes 35 degrees and steeper today. Slabs will be the deepest on wind-loaded slopes. High elevation northerly aspects are the most suspect for poor bonding as the new snow fell onto weak older snow and possibly surface hoar. Warm temperatures for much of the weekend followed by cooling will have helped stabilize the new snow. However, the snowpack is untested and it will be important to look for recent avalanches, shooting cracks and drifted snow, and listen for whumphing. Ease carefully into steeper terrain and use safe travel protocols. There is some uncertainty today about cloud cover and direct sunshine. Pay attention to changing surface conditions and watch for roller balls. On solar aspects warming may increase instability and likelihood of triggering.
PERSISTENT SLABS: Steep northerly slopes above 3000′ also harbor buried surface hoar and near surface facets that were buried 1-2′ deep on April 5th. Two human triggered avalanches occurred just over a week ago failing on this layer. There is a chance that triggering an avalanche in the storm snow on a north aspect above 3000′ could step down resulting in a large avalanche breaking deeper in the snowpack.
Sunburst wind profile over the weekend. Pay attention to loading patterns and watch for cracking.
Wintery weather on Tincan, Sunday April 21st. Photo: Ray Koleser
There is a chance that the sun could come out today or tomorrow and warm up the new snow. If this happens watch for signs that the surface is becoming wet. Roller balls may build into loose wet avalanches. Due to the amount of new snow these could become large as they entrain snow. Change aspects if the snow starts to show signs of warming and be especially suspect of being on or under steep, rocky, southerly terrain.
CORNICES: There are still large cornices along ridge tops. They will have grown during the storm and may be tender. Give them lots of space as they can break farther back than expected.
GLIDE AVALANCHES: It’s been over two weeks since our last known glide avalanche, but keep in mind glide cracks are continuing to creep downhill. As always, limit traveling under their runout. They are unpredictable and can avalanche at any time.
Yesterday: Skies were mostly cloudy with pockets of good visibility. There were snow showers on and off throughout the day with snow falling to sea level and a few inches of accumulation. Winds were variable gusting into the 20s. Temperatures ranged from in the high teens and 20Fs at upper elevations to right around 30F at sea level. Overnight temperatures cooled slightly and winds remained light.
Today: Mostly to partly cloudy skies. There is a chance of snow showers. Winds will be light and easterly. Temperatures will be in the 30Fs to 40F at sea level and in the 20Fs at upper elevations. Overnight snow showers are likely, temperatures will cool slightly and winds remain light.
Tomorrow: Mostly to partly cloudy skies. Slight chance of snow showers. Winds continue to be light and temperatures will be similar to Tuesday. Looking ahead there is sunshine and warmer temperatures on tap for Thursday and Friday.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||27||1||0.1||74|
|Summit Lake (1400′)||27||2||0.2||21|
|Alyeska Mid (1700′)||27||2||0.19||69|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||23||SW||3||8|