Early Avalanche Season SummaryDecember 6th, 2019
by Nikki Champion (Forecaster, Utah Avalanche Center)
In mid-September, we got our first dusting of snow in the Central Wasatch. On Sept 20th, we got about 3 inches of snow with .4 inches of water, followed by another 3 inches of snow and .85 inches of water. Following that we didn’t get much until mid-October. Between October 17th and October 21st, we got another 20 inches of snow. Following this initial pulse, a week of clear weather followed where temperature crusts on the northern aspects formed, and most of the snow on sunny aspects melted.
At the end of October, we got one more fall storm, bringing an additional 18 inches. After that, we were high and dry for most of November. The dry spell cleared most of the snow off the southern aspects, but what was sheltered on upper elevation north-facing slopes was a mixture of temperature crusts, buried surface hoar, and weak facets. This left a very weak, faceted snowpack to be the building blocks for the rest of the season.
Then Came the Thanksgiving Storm!
Before Monday, November 25th, November was on track to be the driest on record (since 1945) at the Alta Guard station. November totals at Alta Guard from Mark Saurer at UDOT are 58 inches of snow (4.53 inches SWE/Snow Water Equivalent). Total snowfall for this season at Alta Guard is 88 inches (7.32 inches SWE). 1976 had the driest November of 13.6 of snow.
Total snow since Monday, November 25th is:
- Central Wasatch Mountains: 50-70″ snow (3.5 – 4.34″ water)
- Park City Ridgeline: 30-40″ snow (2.5 – 3.0″ water)
- Ogden Mountains: 40-50″ snow (4.0 – 4.8″ water)
- Provo Mountains: 24-33″ snow (1.6 – 2.1″ water)
- Uinta Mountains: 25-35″ snow (2.0+” water)
Moving into the coming weeks the snowpack will slowly gain strength, but mid and upper elevation north-facing slopes are still suspect. Avalanche activity in the first week demonstrates that dangerous avalanche conditions still exist on any slope that had snow before the Thanksgiving storm. We now have a 2-3 foot slab of strong snow sitting on top of a foot of weak facets at the ground. These lingering facets can be found above 8000’ on aspects facing NW, N, NE, E. It is a slow healing process, and the snowpack needs time to adjust.