Winter storms that affect Utah generally originate in the North Pacific Ocean, where cold Arctic air encounters the relatively warmer Pacific waters. As these storms move inland some of their moisture falls over the Cascade and Sierra Nevada Mountains. However, upon encountering the abrupt rises of the Wasatch and central/southern Utah mountain ranges, the cold, wet airmasses rise "orographically"--or are forced upward by the rise in surface elevation. The airmass cools further as it rises, leading to enhanced condensation and precipitation. Higher altitudes and generally lower temperatures produce the colder, drier "powdery" snow for which Utah is known.
It is the structure of the snow crystals that makes Utah snow unique. Utah is the second driest state in the nation (after Nevada), and the cold, relatively dry conditions produce light, crystalline snowflakes called "dendrites." These snowflakes are thick and symmetrical, and float slowly through the cold atmosphere to the surface, accumulating as fluffy "powder" in the mountains. Often, storm fronts that move through northern Utah are followed by brisk northwest upper-level winds, which are aimed directly the mountain peaks. Additional moisture is drawn from the warmer waters of the Great Salt Lake, which never freeze, and snowfall in the mountains may continue for days, even after the main storm has passed. It is not unusual to see an additional 24-36 inches of snowfall in the day or two following a storm, all because of this northwesterly flow of cold air across the Great Salt Lake and over the Wasatch Mountains. After such a storm, skiers will likely find several feet of fluffy powder at the resorts.
During late winter and early spring, tropical moisture sometimes arrives from the central Pacific. Due to the warmer source of this moisture, subsequent snowfall in Utah is often heavier and denser, with a higher moisture content. These late season wet snows undergo a thaw-freeze cycle as the days grow warmer, producing icy "corn snow" conditions, which makes for faster skiing.
Average temperatures in winter range from the single digits to the low 30's, with sub-zero readings common on clear nights following a storm. Highs may reach the 40's or 50's just preceding a storm front. Elevation is the greatest factor, as temperatures generally change 5°F per 1,000 feet in elevation. When inversions form in the valleys, ski resorts are often warmer. Of more concern is the wind-chill, which indicates the "apparent" temperature or "what it feels like." Wind chill is based on air temperature and wind speed. The higher the wind speed, the colder "it feels" on exposed flesh. Frostbite can occur quickly when wind-chills fall into the sub-zero range.
At Utah's northern ski resorts, mid-elevation snowfalls vary from 200 to over 500 inches per year. Utah's southwestern ski resorts average mid-elevation accumulations of over 300 inches per year. Most of the ski resorts in northern Utah usually receive their greatest monthly snowfall during December or January. The ski resorts in southwest Utah usually get their largest monthly snowfalls during January or March. The greatest six-month snowfall total ever recorded in Utah skiing history occurred from November 1983 through April 1984, when two of the highest ski resorts in northern Utah recorded snowfall totals of between 650 and 700 inches near their base elevations.
Estimated Average Snowfall at Utah's Ski Resorts:
* November-April snowfall
** Annual Snowfall
Elk Meadows/Mt. Holly**
Note: Base, Mid-level and Summit elevations are in "feet" above sea level. "Inches" means inches of snowfall.
Much of the information for this section originally appeared in the copyrighted book Utah's Weather and Climate, edited by Dan Pope and Clayton Brough, in 1996. UCCW Directors have received permission from the copyright owners of this book to reproduce such information on its website and to revise and updated it where appropriate.