This dry weather has us all wondering where the snow is this season. Will we be skiing on Thanksgiving? Or is there truth to the perception that the season is shortening and that the real snow won’t come until February or March?
Unfortunately, OutThere Colorado doesn’t have a snowpack crystal ball, but we spoke with someone who is probably as close as we can get in human form. Founder and CEO Joel Gratz of OpenSnow, the most trusted team of weather forecasters for skiers and riders around the world, let us in on some of his methods for predicting the 2016-2017 season. And as we learned, mountain forecasting is tricky business—Even the most seasoned forecasters with the most educated guesses are often stumped and proven wrong.
As Gratz explains, it turns out that predicting mountain snowfall has something to do with El Niño and La Niña, temperature, and wind direction. We talked about weather trends, wind direction cheat sheets, and the location that offers your best bet for a Colorado powder day this season.
Can you comment on some trends that you’ve observed over the past ten years while forecasting in Colorado? Or is that ultimately a useless metric and is it more useful to look at weather patterns and trends over much longer periods of time?
In terms of actual weather trends, 10 years is way too short of a time to look at trends. When you look at weather stations in the mountains for the last 30 to 40 years (all the data is available online), there is a noticeable trend for most mountain weather stations in Colorado: Not all, but many, show increasing temperatures by a couple of degrees. But in terms of precipitation (snowfall, rainfall), there’s not a clear statewide trend that I’ve seen in the data or that other researchers have seen. Over the last century, there’s a rather clear trend of increasing temperatures on average. Not every station will consistently show increasing temperatures, but on average the temperatures seem to be rising by a couple degrees. But the trend in precipitation is really flat, i.e., there’s no confident trend to tell us whether we’re having more or less precipitation.
What are some of the factors that you look for to come together for a powder day storm?
The biggest factor in Colorado is wind direction. So if you have a storm coming, the best thing you can do is look at the wind direction near the top of the mountain at about 10,000 to 15,000 feet. The wind direction is a big factor when figuring out which areas will have the most snow. That’s because when the wind hits a mountain, it’s forced to rise and rising air basically creates precipitation. You want wind to come from a certain direction so when the winds are going over the ski area, they are rising and not descending.
I have a cheat sheet of wind directions that are favorable for certain mountains, and I’ll often talk about that in the Daily Snow [regular weather updates] whether the wind is from the Northwest or the Southwest or the west or even from the east. Each mountain has a preferred wind direction that will help them get the most snow.
But wind direction is not the only thing that controls how much snow falls, there are many other factors. But I would say that if you get the wind direction right, you’ll get in the ballpark of which mountains may have gotten the most snow about two thirds of the time.
What’s the longest range you can comfortably forecast out? What does 2016-2017 look like?
The furthest out we can comfortably forecast any individual storm is about seven-ish days. Ish. And that’s not the details of a storm, that’s just knowing that a storm is coming in seven-ish days. It’s really in the two to four day window that we start to be able to finalize our forecasts and figure out which areas might have a powder day and when.
Beyond seven days, we’re basically looking at weather patterns over time and the relative conditions such as warmer and drier conditions or snowier and colder. So seven to 15 days out, we’re looking at patterns, but not necessarily storms.
And beyond 15 days, there’s very little foresight in the forecast, which leads into your next question about how we’re looking at the whole season. I would say I have nearly zero clue here in Colorado leaning one way or the other good or bad. At this point, average is still a pretty good forecast. One of the things that meteorologists look at when forecasting out many months into the future like you’re thinking about here is El Niño or La Niña, which are above or below average water temperatures out in the Pacific Ocean. Those water temperatures have a semi-predictable influence on the weather patterns in the US. I say “semi” because sometimes you can look at El Niño or La Niña, make a prediction for the season, and sometimes it comes to fruition and sometimes it doesn’t. Last year was a prime example: the 2015-2016 season had a strong El Niño, one of the strongest on record, and that often leads to more precipitation in the southwestern United States and less in the Northwest, but that didn’t exactly happen. The Northwest had a pretty good year and the Southwest started strong but ended on the drier side. So even last year with one of the strongest El Niños on record when we should have had more confidence and have made a more accurate long range prediction, it still was wrong. So now this year, we’ve got almost nothing. It’s not El Niño, it may be a very weak La Nina, but we don’t have a strong signal, so without that strong of a signal, our confidence in our ability to predict this season’s snowfall is limited. If you pushed me, I would say that the Northwestern parts of the U.S. and maybe the northern half of Colorado might do better than areas further south. I mean, that guess is supported by science, but it’s not very confident.
Which mountain is the most difficult to forecast?
Just like everywhere in the country and in the world has its unique challenges, every mountain has its unique meteorological challenges. If you look at it in the opposite way, a place like Wolf Creek is almost guaranteed that it’s going to dump when you get a southwestern storm with winds from the southwest. That ability to predict easily is semi-rare when you move more into the interior of Colorado or when you look at a place with mountains surrounding the entire resort. Wolf Creek is kind of on the edge of the mountains of Colorado down in the San Juans, and it has an unobstructed path from the southwest so when storms come in from that direction, it’s more of a sure bet that they’re going to have a ton of snow. Whereas, when you get winds from the west and northwest, it’s usually better for central and northern Colorado. But every mountain has its quirks, and other mountains can be a little bit more hit or miss. So I would say that one of the easier locations to forecast is Wolf Creek on a southwest flow.
There you have it, no one really knows when it’ll start to snow this season. So do your snow dances and keep the faith because this is Colorado, and ski season is well on its way. See you out on the slopes!
Joel Gratz has almost 20 years of forecasting experience. After graduating from Penn State University in 2003 with a degree in meteorology, he moved to Colorado to pursue graduate work at CU Boulder in Environmental Studies and an MBA. OpenSnow launched in 2011 and has since become the leading authority for mountain snowfall forecasts. To access his weather forecasts this winter season, check out opensnow.com or download the OpenSnow app. The OpenSnow team has also released a brand new app called OpenSummit dedicated to forecasting weather for Colorado fourteeners.
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