OpenSnow’s Joel Gratz: Long-range forecasting is like predicting the Super Bowl
EAGLE — How much might it snow this winter? No one really knows for sure, especially not this time of year.
Open Snow recently released its long-range forecast for parts of Colorado, but does it really matter?
“The thing is with these seasonal forecasts, most people just want to have a clue about what might happen,” meteorologist Joel Gratz said in August. “The seasonal forecasts are fun to talk about, but you have to keep in mind what’s predictable and what’s not.”
Top 10 Steamboat Resort winters
• 489 inches, 2007-08 (strong La Nina)
• 447.75 inches, 1996-97
• 447.5 inches, 1983-84 (weak La Nina)
• 441.25 inches, 1995-96 (moderate La Nina)
• 433 inches, 2010-11 (strong La Nina)
• 432 inches, 2005-06 (weak La Nina)
• 423.5 inches, 1992-93
• 405 inches, 2008-09 (weak La Nina)
• 383.5 inches, 1981-82
• 370 inches, 2015-16 (very strong El Nino)
Gratz likens snow forecasts this time of year to predicting who’s going to be in the Super Bowl at the start of the NFL season.
“It’s pretty fun to do the exercise and look at who’s on what team, who could really shine and what rookies could come through, but nobody really knows what’s going to happen,” he said.
What is reliable, Gratz said, is shorter-term forecasts.
“There’s rarely a storm now within sevenish days that occurs without knowing that the storm could occur,” Gratz said. “It could be much stronger or weaker and drop more snow or less snow, but you generally know within sevenish days or so that a storm is coming.”
How it works
Long-range forecasts this time of year focus on water temperatures across the globe, finding a weather pattern in the past 50 years that is similar and then looking back at past years to see what happened in the ensuing winters.
Are they reliable this far out?
“Not really,” Gratz said.
However, weather patterns this time of year fall under very strong, strong, moderate or weak groupings. Gratz said very strong patterns are very reliable, but once they drop to strong and lower, they’re not as reliable.
In the past 68 years, there have been three very strong El Nino patterns and seven strong La Ninas — 10 strong or very strong patterns in the past 68 years equates to one every 10 years. The last very strong El Nino was winter 2015-16, when Steamboat Resort received an above average 370 inches.
“The rest of the time, you’re kind of scrapping,” Gratz said.
Weather patterns are tricky to predict, Gratz said, and there’s much more to it than simply the water temperatures in the ocean — such as jet streams.
However, a common misconception is that there are independent variables related to weather patterns.
“The jet stream is not a driver of weather, it is the weather,” Gratz said.
When forecasters talk about El Nino and La Nina, they are also talking about what those mean to changing the jet stream and the moisture.
“When we talk about water temperatures effecting storm tracks, that’s what we’re talking about: El Nino effecting the jet stream and all of the things around it which bring us snow or doesn’t bring us snow.”
And when it comes to forecasting Colorado, the dividing line for weather patterns can run right through the state.
Read the full story at VailDaily.com.
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