How the mountains of Colorado make natural snow

Newsroom Snow Science How the mountains of Colorado make natural snow

Did you ever wonder why Colorado snow can often be fluffy, light and so much fun to ski or ride? Well, here’s the answer: Snow forms and falls in places where the temperatures are close to the freezing point of water (32 degrees Fahrenheit). Crystals within snowfalls may start to melt as they fall under those conditions and land and settle in as part of the snowpack. Rocky Mountain snow is dry because most of it falls at high altitudes just where we want it to fall, where the temps tend to drop below that freezing point.

Here’s how it works: When moist wind hits a mountain, it is forced to rise. Rising air expands due to lower pressure and this expanding air cools, allowing the moisture to condense into the snow. This process is called orographic lift and is responsible for creating more than half of the snow that falls for the resorts on larger mountains. Let’s take a look at the mountain ranges in Colorado, how these ranges create their own weather, and where you can find the highest snow totals.

Big snows at Vail
The pow day at Vail picked up 15 inches of snow. Pow Wow!

Precipitation in general (obviously including snow) requires three ingredients say the meteorologists at Colorado State University: a source of moisture; upward vertical motion or lift; and instability. We get these ingredients in specific ways during a Colorado winter. The moisture source comes to us from the Pacific Ocean (several states to the west of us). The air that flows over the mountains provides an upward lift. The passage of a storm front or the convergence of several different air masses provides instability.

The climate of Colorado is continental, meaning that it is far from an ocean moisture source. This often means less snowfall than states that are closer to the coast, but it also means light, dry snow is the normal type of powder. The Colorado mountains tend to wring out the moisture of the atmosphere, so that results in normally heavy snowfall during the prime skiing and snowboarding season. The mountains where we ski also benefit by being centrally situated where storms coming to Niña from the Pacific Northwest (Seattle) and the Southwest (Los Angeles) impact the snow totals.

Colorado Regions

These Colorado Regions pack in the snow.
These Colorado regions are known for the best snowfalls.

The most snow falls in the southern San Juan mountains and also in the Park range. You’ll notice that these two ranges are on the southern and northern edges of the state, and there is a good reason that the highest snowfall totals are found here. When moisture is blown in from the Pacific Ocean, the edges of Colorado rob the atmosphere of moisture (in the form of snow) before it reaches the middle of the state. Resorts like Wolf Creek and Silverton sit in the southern part of the San Juans and often see the most snow in the state. Steamboat is located in the Park Range and can also experience some of the highest totals in the state.

In fact, the average annual snowfall in Wolf Creek Pass (10,850 feet) is nearly 400 inches and some years it exceeds 600 inches. But Manassa, just east of Wolf Creek Pass barely receives 40 inches annually. Go figure.

The mountains nearest to Denver and along the continental divide can see the deepest snow from storms that linger to the southeast of Colorado and create winds from the east. These easterly winds strike the continental divide head on and create lots of snow. In fact, the highest 24-hour snowfall total in the United States is owned by a location in this region just up the road from Eldora ski area. The record was 76 inches in 24 hours and was set on April 14-15, 1921.

Mountains along Interstate 70 are some of the most skied in the state due to the access from the highway. These mountains do receive good snowfall, but mostly from one wind direction. Storms that bring winds from the northwest drop the most snow on mountains such as Vail, Copper, Breckenridge, and Loveland. This wind direction means that few mountains block the moisture before it hits the I-70 peaks and drops its powder.

Finally, the Elk range is a massive grouping of high peaks and includes resorts such as Aspen and Crested Butte. The most favorable wind direction for these mountains is from the west. The San Juans to the southwest tend to block storms coming from that direction, and a northwesterly wind tends to not provide as much snow as a wind from the west.

Snow amounts at one mountain can be double or triple those at a resort only 10 miles away, and this is all based on mountain location and wind direction.

Fun Facts

How important is that Colorado snowfall? Consider this: Much of the water supply for seven western states begins in the Colorado Rockies. Weather.com tells us that Colorado holds the record in the “lower 48” for the most snowfall in a 24-hour period. But, it was a while back. It happened when Silver Lake, 40 miles northeast of Denver,  received 75.8 inches of snow in 1921.

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