Weather service predicts weak El Nino
October 7, 2012
EAGLE COUNTY – The National Weather Service recently announced that the development of El Nino conditions in the Pacific Ocean has slowed.
What it means is that it’s now “unclear whether a fully coupled El Nino will emerge,” according to the weather service.
In terms of winter snow conditions, however, there’s no telling what it means.
El Nino, a weather phenomenon characterized by unusually warm water temperatures in parts of the Pacific Ocean, has brought huge amounts of snowfall to Colorado’s southern mountains in previous years, while La Nina, which features unusually cold water temperatures in the Pacific, has blessed the northern part of the state with massive snowfall.
The Vail area and Interstate 70 corridor, however, tend to fall in the middle of the storm tracks. Sometimes the northern storms will hit us, sometimes the southern storms will, and sometimes the central region is left out to dry.
The weak El Nino pattern doesn’t tell weather forecasters any more about snowfall for the region, either.
“Unfortunately, I think, (the weak El Nino) gives it toward equal chances instead of saying much about chances for excessive snowfall or a dry winter,” said Dennis Phillips, a forecaster with the National Weather Service in Grand Junction.
The weaker weather phenomenon just makes everything less certain – but how certain are weather forecasts, anyway?
They can be very certain, said meteorologist Joel Gratz, but it depends on how far out in advance they’re made.
Gratz, who runs the website opensnow.com which predicts storms that will bring powder to skiers and snowboarders, likes to make his predictions within about a week or two of when storms will actually arrive.
“Our main focus is to give actionable, useful information and long-term projections of snowfall for skiers and snowboarders are not actionable or useful,” Gratz said. “There’s not much we can say 1 to 6 months out about the weather.”
And the most recent news about El Nino doesn’t change anything, Gratz said. Average-to-weak El Ninos or La Ninas typically don’t help out the I-70 region much.
“There’s not much we can draw from that,” Gratz said. “Being in central Colorado, there’s not a whole lot El Nino can tell us.”
Because the central region isn’t very north or very south, there’s simply no way to know how the patterns will affect the area, Phillips said.
In comparing previous winters, the 2010-11 winter – the best in Vail’s history in terms of snowfall – was a moderate La Nina year. Last year – one of the worst seasons in Vail’s history – was a weak-to-moderate La Nina.
“It goes to show that (El Nino and La Nina is) just one factor of many controlling how much snow falls,” Gratz said.
At the National Weather Service in Grand Junction, climate expert and meteorologist Joe Ramey recently looked at data for El Nino seasons that follow La Nina seasons, such as the upcoming season.
Phillips said in that research, nothing stood out in terms of weather patterns.
“He decided there’s nothing you could really hang your hat on,” Phillips said.
That being said, the weather service’s current forecast for the upcoming winter is for precipitation in early winter or late fall, followed by a dry period and then “hoping for a wet spring.”
If the El Nino pattern appeared stronger, Gratz said he’d feel more comfortable about predicting general weather patterns for certain regions around the United States, although the Summit region wouldn’t be one of them.
“For central Colorado, it’s just very difficult,” he said.
Gratz will be watching individual storms, however (by the way, he said one is coming toward the end of this week that will bring rain and snow to the area), which can make or break and entire winter season.
Two seasons ago, the big snow season, Gratz looked at a weather station between Aspen and Crested Butte on Schofield Pass and noticed there were about 40 storms that passed through that winter. Two of those 40 storms accounted for 25 percent of the total snowfall at that weather station for the entire winter, Gratz said.
He looks at it as proof that while trying to predict storms ahead of time might be fun for powderhounds, a couple of storms that take the perfect path toward Summit could be all it takes to make or break a season.
And Gratz said not to put too much thought into early snowfall this month. He has researched whether snow in October is indicative of how the rest of the season turns out and has found no correlation.
During the 2007-08 winter, for example, there was almost no snow throughout the fall and early winter, and then about two weeks into December it started falling and barely stopped for the rest of the season.