Another round of snow and wind is on the doorstep today and into tonight. Turnagain only looks to receive a few inches out of this and Girdwood/Portage areas up to 6″ or more. What this will do to the snowpack is add an incremental load, which in our current snowpack set-up is significant. We did not receive any reports of avalanches being triggered yesterday, however on Friday (Feb 1st) several large slab avalanches were triggered. All of them failed on a weak layer of buried surface hoar 1-3′ below the surface. They are summarized in yesterday’s avalanche forecast if you missed it.
The concerning thing is, these avalanches are hard slabs, propagating across entire slopes and proving to still be reactive. They have been predominantly triggered remotely from or near ridgelines. Although the avalanches triggered so far have been in the Seattle Ridge zone, this weak layer is known to be widespread in the region. With another load of wind deposited snow today, these hard slabs on buried surface hoar are being pushed more toward their tipping point. The size and scope of this avalanche problem is nothing to mess with. Cautious route-finding is essential and steering clear of avalanche terrain above the trees is a good way to avoid the hazard. No signs of instability are likely to be present before a slope releases and therefore, we have to remember a bad layer is lurking below our feet.
Jr’s Run avalanche, triggered remotely from the ridge on February 1st (you can see snowmachine tracks along the ridge if looking close). Photo taken February 2nd. Although this looks like three separate slides, these were all triggered close to the same time from the ridge. Interesting how the middle portion remains intact.
Widowmaker avalanches, triggered February 1st. The ‘Looker’s right’ avalanche was triggered remotely from the ridge an hour or so after the main path ran. The main path was triggered near the crown by a snowboarder and that crown wraps around, out of view to the left side of photo. Very impressive, and scary, propagation.
The thin gray line the arrow points to is the weak layer under the surface we can’t forget about.
Ridgetop winds are picking up this morning from the east and expected to blow in the 25-35mph range today. With loose surface snow and 2-4″ of new snow available to transport, wind slabs on leeward slopes should be expected. These are expected be fairly shallow, a foot or less in thickness, yet could be easy to trigger.
It appears that glide cracks are opening again and a glide avalanche released in the Summit zone recently. Heads up to look for glide cracks and limit exposure under them!
Glide avalanche on a southerly slope just north of Manitoba. First noticed Feb 1st. Photo: Patrick Machacek
Yesterday: Partly cloudy skies and sunshine filled the region yesterday. Ridgetop winds were light and variable during the day and have switched to the east overnight, increasing to the teens with gusts to 30mph. Temperatures were civil, in the 20’sF at sea level and valley bottoms with the teens along ridgelines.
Today: A southwest flow is ushering moisture up Cook Inlet, bringing snow to the western Kenai mountains and setting the stage for significant snow in the Hatcher Pass area. This flow direction typically leaves Girdwood and Turnagain out of the fun. We can expect cloudy skies with 2-4″ of snow today and another 2-4″ tonight. Ridgetop winds will be 25-35mph from the east with stronger gusts. Temperatures look to rise to near 32F at sea level, bringing a rain/snow mix, while ridgetops should remain in the teens.
Tomorrow: A brief break between fronts may clear skies tomorrow during the daylight hours before warmer air and precipitation heads in later in the day and into Tuesday. An active pattern seems to be in place for most of the coming week.
*The Seattle Ridge anemometer (wind sensor) was destroyed. We are currently working to replace it.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||21||0||0||57|
|Summit Lake (1400′)||19||0||0||23|
|Alyeska Mid (1700′)||21||3||0.14||47|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Sunburst (3812′)||17||variable||8||30 from east|
|Seattle Ridge (2400′)||18||*N/A||*N/A||*N/A|