El Nino expected to bring a colder Md. winter
Forecasts call for snowiest year since 2002-2003, or not
By Frank D. Roylance Baltimore Sun reporter
October 16, 2009
If you're a Marylander and you love snow, you'll want to listen to AccuWeather.com's chief meteorologist, Joe Bastardi.
If he's right, Maryland is in for the coldest, snowiest winter we've seen since the memorable - and snow-choked - winter of 2002-2003.
But if you can barely tolerate the slippery, icy, sloppy stuff, maybe the winter forecast from the National Weather Service's Climate Prediction Center will sound better to you. Its forecasters expect a colder-than-average winter in the Mid-Atlantic states, but they're less confident about whether whatever falls from the sky will be snow or rain.
"We've seen with El Nino winters [like this one] a couple of years with absolutely no snow in this area. But we've also seen winters with some record-breaking snows. It's a feast-or-famine type of situation," said Mike Halpert, deputy director of the Climate Prediction Center.
October is the season for winter forecasts, and as usual, uncertainty reigns. AccuWeather.com's Bastardi is excited as always. (Last year he predicted 20 inches of snow for Baltimore; we got 9.)
The National Weather Service folks are characteristically cautious and measured. And in the end, nobody really knows what will happen until it happens.
"Seasonal forecasting is in its infancy," Halpert said. "We started issuing these forecasts back in the mid-'90s."
And here's how they've fared. They figure that random chance - "luck" - would make their seasonal forecasts (near average, above average or below average) correct one-third of the time.
"We're right for temperatures in the neighborhood of one-half the time," Halpert said. On precipitation, it's less than that.
For El Nino winters like this one, "we do typically score somewhat better than that." Strong El Nino events have produced some of the weather service's most successful seasonal forecasts.
El Ninos occur every three to five years when the surface waters of the central and eastern tropical Pacific become significantly warmer than the average - by a couple of degrees at present. That influences the track of the jet streams across the Pacific, which in turn influences weather patterns across North America in ways that scientists have come to understand fairly well.
For example, the northern and western states tend to be warmer than average during El Nino winters; California sees more storms off the ocean; the Midwest tends to be drier and milder than average; and the Southeast tends to be cooler and wetter than average.
At AccuWeather.com this week, Bastardi cited El Nino as the chief reason why he expects the core of this year's wintry weather to shift out of the Midwest, where it was last winter, and into the Mid-Atlantic states. Asked for a prediction for Baltimore, he did not hesitate to crawl out on a limb: "Twenty-five inches at BWI, and 2.7 degrees below normal," he said.
The average snowfall for Baltimore for the 30-year period from 1971 to 2000 was 18.2 inches, and the city has only topped that once since the big snows of 2002-2003. Even then (in 2005-2006), it was by less than an inch and a half.
Bastardi isn't predicting anything like the 55 inches the airport recorded in 2002-2003. But a snow total of 25 inches would seem like a lot after six winters in a row with less than that. The past two winters combined produced less than 18 inches of snow.
On the other hand, he said, "It has the potential to get there [55 inches]; don't get me wrong."
Among the other factors that Bastardi takes into account, in addition to El Nino, are winter analogs - past winters when conditions were similar to those setting up this year. He sees similarities between this year's patterns and those that prevailed during the winters of 1976-1977, which was very cold, and 1977-1978, which saw 34 inches of snow at BWI. He also sees a resemblance to the winter of 1957-1958, which brought 43 inches of snow to Baltimore and very wintry weather in February and March. "There are some very heavy hitters coming to the plate," Bastardi said.
Bastardi thinks the bad weather will get off to a late start.
"I would say that we will remember more what happens in January and February than in December." He predicts a "threat of 30 to 45 days of outstanding winter weather, with two or three snowstorms and temperatures averaging more than 5 degrees below normal for two or three weeks in the heart of winter."
Halpert, at the Climate Prediction Center, declined to offer any such specific predictions for our region.
"Snow is something we don't forecast here," he said. That's because whether precipitation falls as rain or snow is largely a matter of timing - that is, whether the storm strikes when cold air is in place or not. And that's too hard to predict months in advance.
Looking back over previous winters in the Baltimore- Washington area during El Nino events, Halpert said, "if you add all the years together there is a tendency for above-average snow." But that, he said, may be an "artifact" of the snowfall data. Snow totals cannot go below zero, but they can go far above average.
Some El Nino winters here, such as 1972-1973, and 1997-1998, saw almost no snow. Others, such as 1982-1983, 1986-1987 and 1994-1995, saw plenty.
This year? Stay tuned.
> Read Frank Roylance's blog on MarylandWeather.com
Copyright © 2009, The Baltimore Sun
By Frank D. Roylance Baltimore Sun reporter
October 16, 2009
If you're a Marylander and you love snow, you'll want to listen to AccuWeather.com's chief meteorologist, Joe Bastardi.
If he's right, Maryland is in for the coldest, snowiest winter we've seen since the memorable - and snow-choked - winter of 2002-2003.
But if you can barely tolerate the slippery, icy, sloppy stuff, maybe the winter forecast from the National Weather Service's Climate Prediction Center will sound better to you. Its forecasters expect a colder-than-average winter in the Mid-Atlantic states, but they're less confident about whether whatever falls from the sky will be snow or rain.
"We've seen with El Nino winters [like this one] a couple of years with absolutely no snow in this area. But we've also seen winters with some record-breaking snows. It's a feast-or-famine type of situation," said Mike Halpert, deputy director of the Climate Prediction Center.
October is the season for winter forecasts, and as usual, uncertainty reigns. AccuWeather.com's Bastardi is excited as always. (Last year he predicted 20 inches of snow for Baltimore; we got 9.)
The National Weather Service folks are characteristically cautious and measured. And in the end, nobody really knows what will happen until it happens.
"Seasonal forecasting is in its infancy," Halpert said. "We started issuing these forecasts back in the mid-'90s."
And here's how they've fared. They figure that random chance - "luck" - would make their seasonal forecasts (near average, above average or below average) correct one-third of the time.
"We're right for temperatures in the neighborhood of one-half the time," Halpert said. On precipitation, it's less than that.
For El Nino winters like this one, "we do typically score somewhat better than that." Strong El Nino events have produced some of the weather service's most successful seasonal forecasts.
El Ninos occur every three to five years when the surface waters of the central and eastern tropical Pacific become significantly warmer than the average - by a couple of degrees at present. That influences the track of the jet streams across the Pacific, which in turn influences weather patterns across North America in ways that scientists have come to understand fairly well.
For example, the northern and western states tend to be warmer than average during El Nino winters; California sees more storms off the ocean; the Midwest tends to be drier and milder than average; and the Southeast tends to be cooler and wetter than average.
At AccuWeather.com this week, Bastardi cited El Nino as the chief reason why he expects the core of this year's wintry weather to shift out of the Midwest, where it was last winter, and into the Mid-Atlantic states. Asked for a prediction for Baltimore, he did not hesitate to crawl out on a limb: "Twenty-five inches at BWI, and 2.7 degrees below normal," he said.
The average snowfall for Baltimore for the 30-year period from 1971 to 2000 was 18.2 inches, and the city has only topped that once since the big snows of 2002-2003. Even then (in 2005-2006), it was by less than an inch and a half.
Bastardi isn't predicting anything like the 55 inches the airport recorded in 2002-2003. But a snow total of 25 inches would seem like a lot after six winters in a row with less than that. The past two winters combined produced less than 18 inches of snow.
On the other hand, he said, "It has the potential to get there [55 inches]; don't get me wrong."
Among the other factors that Bastardi takes into account, in addition to El Nino, are winter analogs - past winters when conditions were similar to those setting up this year. He sees similarities between this year's patterns and those that prevailed during the winters of 1976-1977, which was very cold, and 1977-1978, which saw 34 inches of snow at BWI. He also sees a resemblance to the winter of 1957-1958, which brought 43 inches of snow to Baltimore and very wintry weather in February and March. "There are some very heavy hitters coming to the plate," Bastardi said.
Bastardi thinks the bad weather will get off to a late start.
"I would say that we will remember more what happens in January and February than in December." He predicts a "threat of 30 to 45 days of outstanding winter weather, with two or three snowstorms and temperatures averaging more than 5 degrees below normal for two or three weeks in the heart of winter."
Halpert, at the Climate Prediction Center, declined to offer any such specific predictions for our region.
"Snow is something we don't forecast here," he said. That's because whether precipitation falls as rain or snow is largely a matter of timing - that is, whether the storm strikes when cold air is in place or not. And that's too hard to predict months in advance.
Looking back over previous winters in the Baltimore- Washington area during El Nino events, Halpert said, "if you add all the years together there is a tendency for above-average snow." But that, he said, may be an "artifact" of the snowfall data. Snow totals cannot go below zero, but they can go far above average.
Some El Nino winters here, such as 1972-1973, and 1997-1998, saw almost no snow. Others, such as 1982-1983, 1986-1987 and 1994-1995, saw plenty.
This year? Stay tuned.
> Read Frank Roylance's blog on MarylandWeather.com
Copyright © 2009, The Baltimore Sun
