Greg Gagne
Forecaster
Our Week in Review highlights significant snowfall, weather, and avalanche events of the previous week. (Click here to review the archived forecasts for the Salt Lake mountains.)
The danger roses for the Salt Lake mountains from Friday, February 14 through Thursday, February 20, 2020:
Summary: A storm moves into the region on Sunday, bringing a period of heavy precipitation and widespread avalanche activity Sunday and Monday. Conditions stabilized as the week progressed.
A LINK to the reported avalanche activity from Friday, February 14 through Thursday, February 20. Below is a heat map showing the aspects and elevations of reported avalanche activity in the Salt Lake mountains from Friday, February 14 through Thursday, February 20:
Friday, February 14: No backcountry avalanches are reported.
Saturday, February 15: No backcountry avalanches are reported. However, several observations indicate weakening snow surface in the top 2-6" above the Feb 7 rain/rime crust, creating a weak layer on top of an excellent bed surface for avalanches to run on.
Sunday, February 16: A strong front enters the region on Sunday morning, bringing a period of very heavy snowfall with widespread natural and human-triggered avalanches reported. Avalanches were running at the new snow/old snow interface or failing in weak snow above the Feb 7 crust. Regardless of the weak layer, many avalanches were running fast and far on the crust.
Monday, February 17: Cold temperatures and increasing winds. Several human-triggered and natural avalanches reported again. One notable slide was a very large natural avalanche that likely ran early in the morning in Toledo Bowl (observation). This slide was 18" deep, 800' wide, and ran 1500' vertical.
The photo below is of a slide 18" deep and 100' wide, failing on a layer of low-density snow that fell at the onset of the storm on Sunday in Snake Creek area.
In the Ogden mountains, a very close call in the backcountry adjacent to Snowbasin Resort. Two riders exited a gate and entered the backcountry. The first rider triggered an avalanche 12" deep, 250' wide, that ran 500' vertical. The rider was fully buried apart for a ski tip sticking out of the snow. The second rider was not caught and was able to find the buried victim, reaching an airway within four minutes. Snowbasin patrol assisted with the rescue and, fortunately, the victim was uninjured. The victim was very lucky as neither rider were carrying any avalanche rescue gear. Link to the observation.
Tuesday, February 18: Two relatively slides are reported, including one in the Birthday Chutes that ran several hundred feet. (observation)
Wednesday, February 19: Two avalanches involving fresh wind drifts are reported, both 12" deep and about 30' wide, failing on weak snow above the Feb 7 crust.
Thursday, February 20: Increasing stability, and the only reported backcountry avalanche is Raymond Glade. Like most other avalanches this past week, this slide ran on weak snow just above the Feb 7 crust. (Observation)
Other observers noting the weakening snow surface due to the cold temperatures and clear skies, with widespread sluffing on steep, northerly aspects.