With a strong inversion in place some Alpine weather stations are already near or above freezing this morning. Alyeska Summit (3664′) is at 35F and the base of Alyeska (100′) is at 13F. Sunburst (3812′) is at 30F and Turnagain Pass DOT (1020′) is at 7F. Summit Lake MP 45 (3800′) is at 36F and Summit Lake DOT (1348′) is at 4F. This is the first day to see temperatures above freezing at upper elevations. It will be important to pay attention to changing conditions. This can sometimes make triggering an avalanche on a persistent weak layer more likely. Be most suspect on steep slopes getting direct sunshine. Look for roller balls and wet sluffs, signs that the snow is heating up. The slab avalanche issues today revolve around older weak layers within the snowpack (persistent weak layers). The most recent weak layer (the Valentine’s near surface facets) sits around a foot deep under the wind affected snow and old wind slabs. This layer has been showing signs that it could still be reactive if you find the trigger point. There was a small skier triggered avalanche observed yesterday looker’s right of Ragged Bowl (near Girdwood) that is suspected to have run on this layer. The second layer down is the MLK Jr buried surface hoar. Although found throughout the advisory area this layer is showing signs of only being reactive in the Summit Lake zone. Additionally in the Summit Lake region there is weak snow near the ground.
If you are headed out today watch for:
– Wind-loaded, steep, unsupported slopes are the most suspect for popping out a wind slab that may be sitting on weak snow.
– Larger and more dangerous avalanches are possible in the Summit Lake and Johnson/Bench peak area where a thinner snowpack exists.
– SUN EFFECT and moist/wet sluffs on steep rocky southerly terrain.
– Cornices. Warmer temperatures at higher elevations can help loosen these monsters and with good weather and ridgeline travel, don’t forget to give cornices a wide berth.
And remember to practice safe travel protocol!
Observer on Max’s yesterday found no signs of instability but found the buried Valentine’s facets to still be reactive, 2.24.19
Large natural avalanches triggered by high winds on 2.21.19 in Summit Lake. If heading that way remember the snowpack is harboring a number of weak layers.
Glide cracks are unpredictable, not associated with human triggers, and can release without warning at any time. The best way to manage this problem is to avoid traveling on slopes directly below glide cracks. A short list of known cracks in popular zones: Magnum, Lipps, Seattle Ridge, Eddies, Lynx Ck. See a new glide crack or one that appears to be opening up? Please snap a photo and send us a quick ob!
Yesterday: Mostly sunny with some high clouds, very light westerly winds and temperatures in the 20Fs in mid to upper elevations. Overnight valley bottoms saw temperatures in the single digits with the inversion in place.
Today: Mostly sunny with a chance of valley fog in the morning. Light winds. With the temperature inversion early morning temperatures in the Alpine are near or above freezing and valley bottoms are in the teens to single digits. Valley bottoms temperatures are forecast to rise into the 20Fs and then dip back down overnight. Upper elevations should stay in the 30Fs to high 20Fs.
Tomorrow: The ridge of high pressure looks to dominate the weather pattern and similar weather looks to be on tap for the remainder of the week with the high temperatures slightly increasing each day and lows in the teens at night in the valley bottoms.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||23||0||0||61|
|Summit Lake (1400′)||12||0||0||29|
|Alyeska Mid (1700′)||24||0||0||56|
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||24||NW||1||6|