Summit & Central Kenai Mtns

Recent Avalanches: The storm that arrived last Sunday ended on Wednesday which made it possible to see new avalanches near ridgelines on Butch Mtn, and Fresno Mtn. It is likely they released on March 11 or 12 as high winds from the ridge were loading these slopes into fresh wind slabs. A few of these may have been triggered by a cornice collapse. On Thursday, multiple wet loose avalanches were seen on steep southerly aspects that were baking in the sun. On March 7 a large avalanche was observed on Templeton Mtn that likely released a few days prior on a buried weak layer.

Weather Recap: Friday and Saturday brought much appreciated periods of sunshine, light winds, and colder temperatures (0 to 20 F). From Sunday to Tuesday a storm tracked into Summit delivering about 5″ of new snow accompanied with strong northeast winds gusting 50+ mph. On Wednesday the clouds began to break and by Thursday the skies cleared with winds decreasing to 5 to 10 mph with 20 mph gusts from the northeast. Temperatures averaged 8 to 40F!

Weather Forecast: Another weekend storm should reach Summit on Friday night. On Saturday up to 5″ of new snow is expected with northeast winds (5 to 15 mph) and gusts (20 to 30 mph), picking up in the afternoon. This looks like a warmer storm with temperatures averaging 15 to 34 F and rain possibly creeping to 1500′ by Saturday night. On Sunday, sunshine may be able to poke through snow clouds in the afternoon with another few inches of wet snow expected. Ridgetop winds out of the east look to gust 20 to 30 mph and the rain line is expected to slowly drop to around 1300′ with temperatures averaging 25 to 35 F.

Although it is a long way off, next week may be sunny with solar aspects receiving a lot of heat from the sun. This may make is easier for slopes in the sun to avalanche.

Avalanche on Butch Mtn that likely released on March 11-12 during last week’s storm. Photo 3.14.2024

The main concern over the weekend will be easily triggering a fresh wind slab 1-1.5′ deep. To make matter worse these will likely be forming on top of a weak layer of surface hoar buried 5″ deep. This typically makes these avalanches easier to trigger and takes longer for them to stabilize. If the new snow comes in heavy and the sun comes out it could make these wind slabs even more likely to release naturally or be triggered by a human. This problem will exist at upper and mid elevations on wind loaded slopes. Areas such as below ridgelines and rollovers as well as in cross loaded gullies are all likely places to find a fresh wind slab. If you feel stiff snow over soft snow, see shooting cracks, or hear whumpfing, it is likely you are traveling on a wind loaded slope and it may be time to re-evaluate your terrain choices. Blowing snow on ridgelines is another clear sign of active wind loading. Because we are uncertain how reactive this the buried surface hoar is, we recommend avoiding steep, wind loaded slopes.

Wet loose avalanches will be likely on steep solar faces if the sun comes out on Sunday and starts warming slopes. March is the time when the sun is a major contributor to avalanche activity. These can be large enough to carry a person off a cliff, into a tree, or into a terrain trap where snow can pile up and bury a person. Rollerballs below rocks, trees, and underneath you, are great indicators that the snow is warming enough to cause a wet loose avalanche. It is best to avoid steep sunny slopes later in the day that have been baking in the sun.

Cornices: We have seen avalanches from last week’s storm that could have been triggered by a cornice fall. This storm will continue to build larger cornices. The afternoon sun can also quickly cause a cornice to fracture, triggering an avalanche from above. Look for cornices as you travel and try to limit time underneath them, especially in the afternoon on sunny days or if they are actively getting wind loaded.

Shooting crack on a small test slope. This is a good way to see how likely/easy it is to create a fracture in a shallow wind slab or weak layer that is closer to the surface. This layer released above a buried layer of surface hoar. Photo 3.14.2024

There are several buried weak layers in the snowpack 1 to 3′ deep that a human is capable of triggering into a potentially large avalanche. The most concerning is a layer of surface hoar buried 5″ deep found from the highway to 2,800′. Yesterday this layer was not bonding well and will be more concerning as the storm adds more snow (a thicker slab) on top of this layer. The President’s Day crust/facet combo is now buried 1 to 1.5′ deep and can be found from the highway to 2,400′. Although this layer is less concerning it is still possible for a human to trigger a surprise avalanche. The January facets are now buried 2 to 3′ deep and may be more sensitive above 2,200′ where the President’s Day crust is thin or does not exist. We have limited information above 2,600′ in Summit so we are uncertain how likely it is for a human to trigger a large avalanche on this layer.

In short, there are multiple weak layers at all elevations that are capable of causing a potentially large avalanche. The storm will add new snow and wind slabs above these layers which will add stress to the snowpack, especially the buried surface hoar. Shooting cracks on small test slopes, hand shear tests that fracture easily, seeing new avalanches, and a whumphfing sound underneath you can tell you the snow is capable of avalanching, however, there may be no clues until a “surprise” avalanche occurs. We can avoid this problem by choosing slopes that are not in avalanche terrain (less than 30 degrees). If you do find yourself traveling in avalanche terrain, it is important to practice safe travel protocols such as exposing one person at a time, moving from safe spot to safe spot, and have an escape route planned.

Several weak layers in the snowpack that are capable of creating an avalanche. Photo 3.14.2024