Although clear skies and excellent surface snow will greet us for the weekend and into the work week, there is a hidden layer of buried surface hoar that could cause us some problems. If you’ve been following along, you’ll know that the New Year’s storm cycle buried a couple layers of surface hoar formed around Christmas; these layers now sit 2-3′ below the surface. There has only been one human triggered avalanche (Jan 2nd) known to have released on one of the layers, which is good news, but more avalanches could be lurking. We are finding the layers in many of our snow pits, though not all of them, and typically only one of the layers. More often than not, they are not showing signs of reacting. Again, this is good news. All this said, it is still likely that isolated pockets exist where a human triggered slab avalanche, large enough to hurt us, will be possible to trigger.
This is a tricky situation. If choosing to avoid the problem all together, stick to lower angle slopes. If headed for the steep terrain, consider the consequences if part or all of the slope does release. Watch our partners and expose one person at a time. No obvious signs on instability are likely to be present and in fact the pack could feel and look completely stable.
A fantastic snow surface makes it hard to remember that there is a ‘thin gray line’ a couple feet under us. Note the line in Trip Kinney’s snow pit from Pete’s North 2,800′. This layer wasn’t reactive yesterday in his pit, but that doesn’t mean some booby-traps aren’t out there.
South of Turnagain – Lynx Creek/Johnson Pass/Summit Lake zone: Not only are we concerned that the Christmas buried surface hoar may cause problems in this area, there remains a poor snowpack structure in general. There are facet/crust combinations that exist in the bottom portion of the snowpack. The New Years storm is believed to have overloaded both the buried surface hoar as well as these deeper layers. Take a look at the photos from the avalanche activity throughout Summit Lake. If you’re headed this way, the pack does become more complex – evaluate terrain exposure and the snowpack as you travel. Remember ‘whumpfing’ and recent avalanches are obvious clues of instability.
Natural avalanche that released at the end of the storm on New Year’s Day on the west aspect between Wilson’s North and Wilson’s South. We are suspect that this avalanche failed on buried surface hoar.
Glide avalanches are expected to release over the weekend. Believe it or not, these cold snaps have been known to trigger releases. Several glide cracks have avalanched over the last few days. Glide cracks have been seen in popular ski and snowmachine terrain and some are covered by new snow from the New Years storm. The best way to manage the problem is to avoid traveling under glide cracks. As a reminder, glide avalanches have occurred on Lipps, Seattle Ridge, Penguin Ridge, Lynx Creek and Johnson Pass this week.
Recent glide crack that released in the northern portion of the Bench peak massif. This area is just southeast of Johnson Pass and seen from the Seward Highway.
Yesterday: Mostly clear skies with some valley fog covered the region. Ridgetop winds were light from a NW direction (5-10mph). Temperatures were cold and inverted; single digits in the parking lots and the teens F along ridgelines.
Today: Mostly clear skies and patchy valley fog will be over the area again today. Ridgetop winds are expected to remain light, 5-10mph, from the NW. Temperatures are cold (-5 to 5F) at the lower elevations and in valley bottoms as an inversion remains. Ridgeline temperatures are in the mid-teens with the warmest weather station being at the top of Max’s Mt above Alyeska at 18F.
Tomorrow: Sunny skies and cold temps are on tap to remain for Sunday and into the week. The good news is, ridgetop winds at this point look to remain light from a NW direction. Models are hinting at the next chance for a precip event next weekend.
*Seattle Ridge weather station was heavily rimed and the 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′)||10||0||0||60|
|Summit Lake (1400′)||-2||0||0||20|
|Alyeska Mid (1700′)||11||0||0||47|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||13||*N/A||*N/A||*N/A|