Storm Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Very Likely
- Größe
- 2–3
After a week of high pressure the first series of January storms is upon us. Unfortunately, these are again fairly warm storms with a rain line up to 2,000' or so. That rain line might lower later in the week but for today it seems 2,000' is it. Ridgetop winds are increasing this morning from the east and should peak midday at 50-70 mph with gusts near 100 mph. Today is a day to let the storm do its thing without us being in the way.
Storm totals from yesterday with expected snowfall today - all snowfall guesses are above 2000':
- Girdwood: 1-1.5" water (~16" snow). Another 3-4" of water today (over 30" snow!)
- Turnagain Pass: 0.7-1" water (8-12" snow). Another 2-3" of water today (over 20" snow)
- Summit Lake: 0.3-0.5" water (3-5" snow). Another 1.5-2" of water today (over 15" snow)
- Seward/Lost Lake: 1-1.5" water (10-15" snow). Another 2-3" water today (over 20" snow)
Dry snow avalanches: Above 2,000' there could be precipitation rates of 2-3" of snow per hour. This is a textbook case for 'rapid loading', which results in natural storm snow avalanches. With 10-15" of snow last night and another 20+ inches today, storm slabs could be 2-3' deep and quite large and dangerous. All this new snow is falling on weak faceted snow, which will only make it more likely for the new snow to avalanche. Many of the alpine slopes will see significant wind loading as well. New wind slabs could build up to 5' or deeper before they avalanche. Finally, cornices. These should be getting bigger with the wet sticky snow and when chunks of cornices fall off, they are likely to trigger slab avalanches below.
Wet snow avalanches: We can safely assume that wet snow avalanches are occurring around 2,000' and below due to rain on snow. There is very little snow below 1,500' so these types of avalanches may be on the smaller side, but either way, avoiding any steep slope and staying out from under steep slopes above you are key for today. Some avalanches in the higher terrain could be large enough to run into snow-free zones.