The History of Southern California Snow Conditions chart is the best expression I've devised for displaying the range and incidence of snow conditions. In order to construct such a chart it is necessary to have week by week reports of conditions. First Tracks Online provides at least weekly reports from Utah's Cottonwood Canyon areas to construct a chart for the past 3 seasons. Based upon early season snowfall incidence I can chart the 25th, 50th and 75th percentiles of Alta/Snowbird snow conditions. As I have personally skied these areas in March in 20+ seasons I can also construct the percentiles during the spring transition period.
The focus of these charts is to show coverage of terrain and
frequency/consistency of packed powder snow that has not been
through a melt/freeze. The weekly grades
are not a measure of fresh powder, which cannot be predicted in advance
for a specific week. In 2008 I derived a method to estimate percent of
powder days from monthly snowfall. I now apply that percentage to all
weeks rated A or B and show that percentage and an adjusted
total grade at far right. For details, see What Is
the Probability of a Powder Day?
|UTAH COTTONWOOD CANYON SNOW CONDITIONS|
|Park City Median||0||D||D||0||C||C||B||B||A||9||A||A||A||A||12||A||A||B||A||11||B||A||B||A||B||12||B||B||4||0||0||0||48||10||18||20||12%||56|
Alta's high base elevation and layout allow it to be about 75% open on a 3-4 foot base. Alta has had less than 100 inches by New Year's in only 2 of the past 41 seasons, and the 25th percentile of pre-New Year's snowfall is about 120 inches. Alta has arbitrary opening (3rd weekend of November) and closing (3rd or 4th weekend of April) dates, but with very early snow (as shown for 2004-05) Brighton will open as soon as there is a sufficient natural base. Snowbird requires more coverage than Alta, though it had enough to open November 5 in 2004.
Snowbird is the best Utah area for spring snow preservation and thus runs some lifts until late May in most seasons. The snowpack in 2004-05 was enough for Snowbird to stay open to July 4, though with its lower water content snow this is about a once-a-decade event vs. 30% at Mammoth. Utah is warmer than other regions in the Rockies, so even at Alta/Snowbird much of the snow will transition to spring conditions in March if it does not snow for a few days. Thus the percentiles show a "checkerboard" pattern from mid-March to April, reflecting the frequent new snow averaging 90 inches in March and 70 in April.
With 500-inch average snowfall it's no surprise that Alta/Snowbird produce high and consistent scores. The combination of Alta's early season and Snowbird's late season results in a bad year in Utah's Cottonwood Canyon being better than a good year in many western ski areas. 2014-15 was particularly noteworthy in having the lowest Alta/Snowbird snowfall on record. But since November and December were only slightly below normal the season was close to normal in length. Subjectively the Utah locals complained, because there weren't that many powder days and melt/freeze condtions prevailed through much of the unusually dry winter months.
A 25th percentile season for Alta/Snowbird would have lower than normal early snow, with Alta and Brighton reaching full operation around Christmas and rockier Snowbird and Solitude shortly after New Year's. The Cottonwood Canyons did not escape the extreme western drought of 1976-77 in early season, but did have substantial February and March snow. The score for 1976-77 would have been about 35 (before powder adjustment), but every other season would have scored at least 50.
Other Utah Areas:
The Cottonwood Canyon microclimate encompasses a relatively small geographic area. The Park City areas (includes Deer Valley and The Canyons) get 50-60% of the snowfall of Alta/Snowbird and also are at lower elevation. Park City on average reaches full operation by about New Year's as its lower terrain is mostly intermediate and has snowmaking assistance, while its steep terrain is high up and gets more natural snow. With sunny exposure the "checkerboard" pattern of spring conditions when there is no fresh snow starts about mid-February. The Park City median in the chart is inferior to even the second worst ever 2014-15 season in the Cottonwood Canyons, but Park City is actually about average for a western destination resort in terms of snow conditions. It would be almost identical to the Squaw Valley median except for Park City's arbitrary mid-April closing date.