Deep Days Coming: The Science of Snow Forecasting
We’ve all felt it, the way those first stray flakes of a big winter storm turn thoughts from school or work to more important things like waxing your board or setting your ski boots next to the heater for the night.
It’s not even snowing yet, but the cars in the parking lot outside the Backcountry office already have their windshield wipers pointed skyward. It might be hopeful thinking, maybe a strange offering to the snow gods, but more likely it’s the knowledge that there’s a storm a-brewin’ and we’ll soon be milking the pow cow.
I spoke with Evan Thayer of Wasatchsnowforecast.com about predicting storms, about what makes good snow, and about what this particular storm means for us here in Utah and for skiers and riders throughout the American West.
“This is an extremely moisture-laden storm with sub-tropical origins,” Thayer said, explaining that we should have a prolonged period of high-elevation snowfall, which will be excellent for early-season snowpack. “While this snow isn’t the typical Utah fluff that makes for great power days, it is still very valuable because this type of dense snow makes for a great base for lighter snow to fall on later in the season.”
A sight to get our hearts pounding … forecast image from wasatchsnowforecast.com.
Thayer says that this storm should impact almost all of the western US, hitting the Cascades and the Sierra Nevada particularly hard. “Unfortunately for them,” he said, “snow levels could be an issue,” snow levels being the altitude at which precipitation becomes snowfall as opposed to rain. “In the Wasatch, our snow levels will rise, but we won’t see the rain at ski resort elevations that the Cascades and Sierra will see.”
I asked him what makes a good storm, and he explained that the three biggest factors are moisture, dynamics, and cold air. “Obviously you need cold air for snow to fall, so that’s a given,” he said. “The more moist a storm is, the more fuel it has to drop snow. Lastly, dynamics are key. This is how much strength and energy the system itself has. Frequently, a strong cold front and well-organized system can allow for intense precipitation rates. Add in plenty of moisture and cold air, and you have the ingredients of a major winter storm.”
Thayer has been a diehard skier and self-proclaimed weather nerd for as long as he can remember. “I grew up in Tahoe and religiously tracked storms moving into the Sierra Nevadas,” he said. “I originally went to school to study atmospheric sciences but decided that I didn’t have much interest in the profession aside from forecasting snow storms.”
He now works in IT, and his website is a labor of love that has become somewhat of a bible to a growing audience of skiers and snowboarders throughout Utah’s Wasatch range.
In forecasting storms, Thayer uses a variety of computer models, each of which is meant for different types of forecasting. Each model has areas where it excels as well as shortcomings, and different models are best for short, medium, or long-range forecasting.
“I keep very detailed records of previous storms and use intuition frequently to determine which forecasting model weight more heavily when making my forecasts,” Thayer said. “A lot of forecasting is dependent on confidence in certain scenarios playing out; I just try my best to use a combination of weather models and personal experience to increase my confidence in one specific scenario being the most likely during winter storms.”
So are these forecasts accurate? Is it safe to call in sick and get the powder planks waxed at the first hint of snow? Thayer explained that meteorology is far from a perfect science. “We still have a long way to go to improve accuracy,” he said. “However, we’ve come a long way in the past few decades, and we are improving every day. The farther out in time a storm is, the harder it typically is to forecast. Forecasts within a few days are generally pretty accurate, but all forecasters, myself included, know that no forecast is guaranteed and Mother Nature can always find ways to surprise us.”
While Thayer is predicting that this upcoming storm will be bringing lots of snow denser than the sought after Utah fluff, we can always hope that Mother Nature will surprise us with the light stuff. I asked just what makes Utah’s powder snow so legendary, and the answer is a combination of quantity and quality.
“Utah mountains get a lot of snow, with several areas receiving close to 500 inches annually,” he said. “Utah snow is also relatively dry and fluffy, owing to generally consistently cold temperatures during the winter. This dry fluffy snow is considered by most skiers to be the highest quality and best for powder skiing.”
According to Thayer, though few and far between, there are places that get more snow than Utah, and there are places like Colorado that can get drier, fluffier snow than Utah. “But,” he said, “there are hardly any places that have the combination of quantity and quality that Utah offers. That is what makes the snow so good.”
With the onset of climate change, each individual storm becomes more and more important for not only skiers and riders but for the world in general. Thayer explained that though climate change is difficult to quantify, he would expect average snow levels in Utah to gradually climb, meaning that snowfall at lower elevations will continue to decrease over time. “Luckily, rain events are still rare in the high elevations of Utah,” he said, “but we could see these become more and more frequent over the next 50 years.”
When asked what we can do to combat the effects of climate change, he said that climate change seems to be very closely related to CO2 emissions worldwide. “Doing what you can to reduce your carbon footprint and educate others about the dangers of climate change is the best way to combat the issue.”