There is a lot of snow available for transport and the winds bumped up early this morning, blowing from the east 20 mph gusting into the 40s on Sunburst. Maxs Mountain weather station saw gusts into the 50s. Look for tender wind slabs along ridgelines, especially on unsupported slopes. Girdwood Valley picked up another 5″ of snow in the last 24 hrs and Turnagain Pass an additional 3″. Since the storm on Sunday avalanche activity has been relegated to small pockets of storm slab, soft wind slab and loose snow sluffs. Today it will be important to watch for stiffer snow over softer snow, cracking and whumpfing (collapsing). Due to more snow in the Girdwood Valley wind slabs could be thicker. As always think about the consequences of even a small slab in steep terrain. As more snow falls today storm slabs may form quickly and be reactive.
Loose snow avalanches: In areas protected from the winds watch your sluff. Sluffs could start getting larger with the cooler temperatures and the quantity of soft snow.
Sunburst weather station’s bump in winds this morning. 12-19-18
Remember there is a lot of snow available for transport! New snow that fell Sunday in Girdwood. 12-16-18. Photo: Andy Moderow
As we have been mentioning for a while now, in thinner snowpack zones such as Summit Lake and Crow Pass, we are tracking buried layers of facets, crusts and buried surface hoar that sit 1-3′ under the snow surface. These layers are most prevalent in the mid-elevations (2000’ – 2700’). A lack of avalanche activity has been pointing to an unlikely chance for an avalanche releasing in these deeper layers. However, Summit Lake has poor snowpack structure and stability tests still show the potential for an avalanche to release. Wind loading this morning will potentially stress these weak layers in upper elevation start zones. As we push out into more and more terrain in areas that may have a thinner snowpack like Lynx Creek and Johnson Pass, we need to keep in mind the buried weak layers.
Fresno snow pit with weak snow near the ground, 12-18-18
We have had several reports that the glide cracks are opening. Glide cracks we know about are on Sunburst’s SW face under the weather station, SW face of Tincan Proper, Gold Pan area (behind Cornbiscuit/Magnum) and a crack that did release in the Johnson Pass area. These cracks can release at any moment. They are not associated with human triggers and the best way to manage the hazard is to avoid being on or beneath slopes with cracks.
Yesterday: Sky cover fluctuated between overcast and obscure. Light snow fell on and off throughout the day. Winds were light and easterly and temperatures were in the teens and 20Fs. Overnight snow showers continued. Temperatures stayed in the teens and 20Fs and winds were calm.
Today: At 4 am this morning easterly winds picked up blowing 20 mph and gusting as high as 56 mph on Maxs Mountain weather station. Today winds are forecast to be 10-20 mph with gusts into the 40s. Temperatures will be in the 20Fs and light snow is forecast to continue falling, 1-6″. Winds decrease overnight and temperatures will be in the teens with clouds clearing out.
Tomorrow: Thursday is forecast to be mostly sunny. Temperatures will be in the teens and winds will be light. Overnight temperatures will drop into the single digits. This cold and clear pattern looks to last into Saturday. Stay tuned for next low moving into the Gulf Saturday night.
*Seattle Ridge anemometer (wind sensor) is rimed over and not reporting. Temperature data went down at 1:00 pm yesterday.
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||20||3||0.2||39|
|Summit Lake (1400′)||20||1||0.1||14|
|Alyeska Mid (1700′)||
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||*18||*no data||*no data||*no data|