LEXINGTON — Judah Cohen is positively giddy that we got hammered this winter. He loved the idea of a snowfall record, but more than that he loves being right.
“I’m really happy,” he says with a grin, sitting in his small, neat office dominated by a huge computer screen that seems in constant motion as he pulls up this weather map or that satellite image. “I thought we did a very good job predicting it.” In fact, his forecast proved better than that of the federal government.
Cohen, 52, a self-described “weather weenie,” is director of seasonal forecasting for Atmospheric and Environmental Research (AER), a Lexington weather-consulting company that counts NASA among its clients. Local weather enthusiasts might recognize him as Harvey Leonard’s go-to guy for long-range forecasts on WCVB-TV (Channel 5).
And Cohen isn’t at all sure that we’re through with winter yet — or rather, that winter is through with us. “The possibility of more snow will continue for at least the next two weeks,” he says.
Perhaps Cohen’s biggest claim to fame comes from the fact that he and his team’s seasonal forecasts of “temperature and precipitation anomalies” have been right 75 percent of the time, a rate that tops those of the major government weather centers, including the National Oceanic and Atmospheric Administration, the federal government’s main weather forecaster. (In fact, Cohen and his team, who have been making predictions for 15 years, bestedNOAA this winter.)
“In the scientific literature our model remains the most accurate to date,” he says.
Cohen’s meteorological prescience is not the only thing that sets him apart. His reliance on the snow cover in Siberia to predict wintry outcomes in America and Europe is unique.
Each October, Cohen looks at the amount and the rate of snowfall in Siberia that month to determine how snowy the eastern United States and Europe will be come winter. “The snow cover is the most efficient reflector of sunlight out into space, so more snow cover creates dense air masses that stay close to the ground,” he says. That cold, dense air spreads over the North Pole into North America and westward into Europe.
Cohen proceeds to go into more detail than the average human can stand, or understand, with terms like “The Aleutian Low” and “The Siberian High”. But for him and us, the bottom line is that this past October was Siberia’s second most extensive snowfall on record, and Cohen knew the implications for Boston and other East Coast cities.
In a nutshell, that’s the way Cohen works. His analysis embraces multitudes of facts and figures, but his forecasts describe big-picture trends. Like the Farmers’ Almanac, you may ask. Not exactly, he laughs. “The Farmers’ Almanac is not scientifically credible and should only be viewed for entertainment value.”
Cohen, by the way, has never been been to Siberia. His research, largely funded by the National Science Foundation, is all computer-based. “The closest I got was Moscow,” he says. He went when the Russian government wanted a winter forecast for 2007-08.
Cohen grew up in Brooklyn, N.Y., and attended Columbia University, where he earned a PhD in atmospheric science. He has loved snow since he can remember, and his office bookshelf is crammed with titles such as, “Blizzard! The Great Storm of ’88,” “Snow and Climate,” and “The North Atlantic Oscillation.”
At 52, the father of three teenagers still takes childlike pleasure in the white stuff. “I have a hard time sleeping during snowstorms,” he admits. “It’s a passion. People say, ‘Yeah, I used to love it, and then I grew up.’ I guess I never grew up.”
Cohen has been at AER since 1998, after finishing a postdoctoral fellowship at MIT, where he advises graduate students in the civil and environmental engineering department. Though he’s very proud of this winter’s prediction, he wasn’t as happy with last year’s. “I predicted it would be mild, but it was a cold, snowy winter,” he says. “It’s the only time I’ve had a miss.”
‘It’ll be an active and interesting winter. We’re predicting above normal precipitation for right along the East Coast. So a wet winter. But I’m especially bullish over the possibility of an above-normal snowfall.’
For the past four years, Leonard has hosted Cohen twice a year for his long-term outlooks: in the fall for the winter forecast, and in the spring for the summer forecast. On Nov. 25, before Boston had any snow, here’s what Cohen told Leonard: “It’ll be an active and interesting winter. We’re predicting above normal precipitation for right along the East Coast. So a wet winter. But I’m especially bullish over the possibility of an above-normal snowfall.”
The rest, as they say, is history.
Cohen’s thoughts these days are turning to summer; specifically, the forecast he’ll make on WCVB-TV before Memorial Day. Summer is always easier than winter.
“We’ve always been right,” he says. “And right now, we’re forecasting a warmer-than-normal summer.” He pulls up a map that is so red it practically glows. “There’s a robust, bullish signal for June, July, and August.”
Pushed for specifics, he’ll only say: “We’re predicting a one-degree warmer temperature for the three-month average, but it’s still early.”
Just after he tapes Leonard’s show in May, Cohen is headed to Ireland on a Fulbright Scholarship where he and faculty at the University of Limerick will provide weather information to farmers in Europe.
Despite his stellar track record, Cohen knows that long-term climate predictions are tough calls. “I do climate,” he explains. “Weather is what you get. Climate is what you expect.” His is a difficult field with a “very low bar for success,” he says.
Still, he laughs as he describes how friends constantly bug him for weather advice — “I get asked all the time” — and when he’s wrong, “I hear about it forever.”Bella English can be reached at email@example.com.