Science behind snow not an exact one
Meteorologist says 2 major factors play into Steamboat snow totals
January 21, 2012
Steamboat Springs — Weather forecasters don't like to be wrong, especially when they are relied on by people trying to plan a powder day.
"I don't like surprises," said Joel Gratz, a meteorologist who founded http://www.opensnow.com, a website that provides daily forecasts specific to ski areas.
His website was calling for 10 to 15 inches of snow to fall overnight Saturday at Steamboat Ski Area. The National Weather Service in Grand Junction called for 8 to 12 inches.
Local powder hounds were looking at the forecast with cautious optimism. After all, the forecasts have been known to disappoint. Meteorologists say that's simply because weather in the mountains can be difficult to predict.
"Where you have mountains, you have a lot more micro climates than you have in the flat terrain like the Midwest," said Jim Pringle, a National Weather Service meteorologist.
Gratz said Steamboat Springs in particular is one of the more challenging areas to forecast for.
"I seem to be more surprised by snow in Steamboat more often than other areas," said Gratz, who was skiing in Steamboat this week while attending the 23rd annual Steamboat Weather Summit.
The summit is hosted by the ski area and attracts meteorologists from across the country who come to listen to speakers and shoot live, remote broadcasts.
Gratz said making accurate snow predictions at ski areas involves having specific knowledge about the area and how it is affected by storms.
There are two major factors for predicting storm totals at Steamboat, Gratz said.
The first is the wind direction. Steamboat is favored by storms that produce a wind coming from the west and northwest, Gratz said. To produce large amounts of snow, you need wind to hit the mountain directly and force air into the atmosphere.
"You need the air to rise, condense, cool and come down as moisture," Gratz said.
The second big factor in producing big snow totals at the ski area is whether there is cold air trapped in the valley.
"It almost acts like a little mountain in itself," Gratz said. "It creates more lift and more snow."
The mountains have a massive influence on the weather and can make it more difficult to predict.
"The computer models that we use aren't big enough to figure out the influence on the weather," Gratz said. "Models get you in the ballpark, but you need a lot of local knowledge."
Multiple computer models are used and the varying predictions are compared.
"We have to understand the basic weaknesses and strengths of the computer models," Pringle said.
He said when all the models give a consistent forecast, it usually proves to be correct.
That wasn't the case Jan. 18, when all the models were calling for 8 to 16 inches of snow on Mount Werner and wind gusts of 70 to 80 mph at higher elevations.
"We didn't get anywhere near that," Pringle said.
The jet stream ended up being farther north than expected, and Pringle thinks the strong winds stayed higher in the atmosphere.
For the National Weather Service, he said being wrong has become less of a problem.
"We are more accurate than what we used to be," Pringle said. "We just try to keep improving upon that."
To reach Matt Stensland, call 970-871-4247 or email mstensland@SteamboatToday.com