Polar vortex may help winter come in like a lamb, go out like a lion Irregularity in polar winds may create warm start, cold end to winter 
 
 Image 1 of / 1 Caption Close Image 1 of 1 Andrea Lang, an assistant professor of atmospheric and environmental science at the University of Albany, studies the polar vortex. She said the vortex, which pens in Arctic cold, is strong now, but could weaken later this winter. less Andrea Lang, an assistant professor of atmospheric and environmental science at the University of Albany, studies the polar vortex. She said the vortex, which pens in Arctic cold, is strong now, but could ... more Polar vortex may help winter come in like a lamb, go out like a lion 1 / 1 Back to Gallery 
 
 Albany 
 
 The polar vortex that brought strong winters to the Capital Region the last two years is showing signs that while winter won't come early this season, it might grow fierce enough later to keep the groundhog in his den, according to a national expert based in the University at Albany. 
 
 Now stronger than average, the vortex — made up of high-speed, high-altitude winds that spin around the North Pole each winter — should keep Arctic cold penned in through the start of the Christmas season or so, according to Andrea Lang, an assistant professor of atmospheric and environmental science who studies the vortex. 
 
 As Weather Channel buffs may already know, there are such vortexes above the planet's two polar regions; faster winds form a tighter circle, acting as a kind of fence to hold in extreme cold from flowing southward. While the polar vortex became a common term during the harsh winter of 2013-14, the science behind the vortex has its beginnings in the 1940s. 
 
 Retreating sea ice around the North Pole seems to be causing that vortex to weaken and loosen its shape, which the last two winters allowed extreme cold to plunge much farther south in the Northeast, including the Capital Region, while places untouched by the vortex, like Alaska, saw record heat and little snow. 
 
 More Information Watch University at Albany climate expert Andrea Lang talk about the polar vortex on the Weather Channel online at: http://bit.ly/1l2rtjk http://bit.ly/1k2WL9L 
 
 A warmer winter matches up with national long-range weather forecasts, which credit a stronger El Nino warming effect in the Pacific Ocean. But Lang said a stronger-than-average polar vortex at the start of winter has a greater chance to grow increasingly unstable as the season progresses, making it more likely that the vortex could become more misshapen, sending late blasts of cold air and snow to some southerly regions. 
 
 The vortex is usually at its weakest — and thus prone to wander — from late December through February. "There is a statistical likelihood that the vortex could become more volatile later in the winter," Lang said. "We will keep watching it." 
 
 But whatever the vortex does this season, consumers should remain snug in their homes without facing costly heating bills — prices for propane, heating oil and natural gas are near record lows and inventories are overflowing. 
 
 In New York, about a quarter-million homeowners, primarily in rural areas, heat with propane. Two years ago, a vortex-driven cold snap coincided with a nationwide propane shortage and rising prices, which added about $100 million to the heating bills in the state. 
 
 "Inventories of propane are at record highs. We have 100 million barrels waiting for winter, where normally we would have 50 million to 60 million," said Tucker Perkins, chief of business development for the Washington, D.C.-based Propane Education & Research Council. 
 
 State energy officials are also predicting that home heating bills should be lower for people who heat with propane (down 18 percent from last year), heating oil (down 25 percent) and natural gas (down 10 percent). 
 
 According to a report this week by the New York State Energy Research and Development Authority, the average home propane bill — which in 2013-14 was more than $4,300 — should be about $3,300 this year. For heating oil, the decline would be from $3,500 to about $2,300. For natural gas, the average bill for the period should drop from about $1,030 to about $930. 
 
 Propane users should breathe easy for the next few years, said Perkins. Supplies of propane, a byproduct of natural gas, are increasing, largely due to natural gas hydrofracking in Pennsylvania, Ohio and other states. 
 
 Since 2008, propane production in Eastern states has gone up more than 600 percent, about 10 times the rate of propane production overall, according to a report this week from the U.S. Department of Energy. 
 
 "For New York, we have more propane coming from the Marcellus Shale (in Pennsylvania). Now, we have a large supply, and flat demand," said Perkins. "Prices are down this year, and we expect prices to remain flat the next four to five years, which should give people who use propane some comfort." He encouraged homeowners to start the season with full propane tanks and have a dealer lined up through the winter to ensure timely deliveries. 
 
 bnearing@timesunion.com • 518-454-5094 ||||| Lane Turner/Globe Staff 
 
 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). 
 
 Advertisement 
 
 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. 
 
 Get The Weekender in your inbox: The Globe's top picks for what to see and do each weekend, in Boston and beyond. Sign Up Thank you for signing up! Sign up for more newsletters here 
 
 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. 
 
 Advertisement 
 
 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.” 
 
 Advertisement 
 
 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 english@globe.com
– Snowfall in Siberia during October has proved to be a remarkably accurate indication of how cold winters in the US will be, according to meteorologist Judah Cohen—and it looks like this winter could be a doozy. Siberia experienced record snowfall and its worst blizzard in 10 years this October, meaning the "Arctic Oscillation" pattern could once again cause the polar vortex to put the US' Northeast in a deep freeze, reports USA Today. But Cohen, an Atmospheric and Environmental Research scientist who describes himself as a "weather weenie," says the very strong El Nino pattern has made this year more complicated than most and for now, he predicts mild weather in the short term. "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," Cohen told the Boston Globe earlier this year while explaining why such an immense amount of snow had fallen on the city, and how Siberian snow predicted it. University of Albany polar vortex expert Andrea Lang tells the Albany Times Union that while mild weather may lie ahead until around Christmas this year, the vortex is currently stronger than usual, which raises the risk of it becoming weaker than usual later in the season, sending fiercely cold weather south. (The Old Farmer's Almanac says the coming winter will be incredibly cold, while the NOAA believes it could be balmier than usual in a lot of places.)