Odds are for a cold and snowy winter

Heading into winter, the region's highway departments might have enough salt and brine on hand to liquefy the Hubbard Glacier in Alaska. And based on the latest winter outlooks, they might need it.

Those who issue long-range forecasts readily acknowledge that they skate on thin scientific ice, that nailing tomorrow's weather is hard enough.

But the consensus is that this weekend's wintry turn is a trailer for what's to come, that the brisk storm traffic will continue.

"This is the first of what's going to be a series," said Henry Margusity, a meteorologist with Accu-Weather Inc. "This weather pattern is just amazing. I think for Philadelphia, you'll have snow on the ground for Christmas."

Forecasters caution that the two big forces driving the winter are imponderables: surprisingly warm water in the equatorial Pacific and a volatile air-pressure pattern in the North Atlantic that Leif Eriksson noticed a millennium ago.

That said, they generally agree that while it might not be memorably cold, it should be memorably stormy. Ten different outlooks by government, private, and TV meteorologists have called for near-average or below-average temperatures. Of the five that took cracks at seasonal snow totals, estimates ranged from near normal, about 20 inches in Philadelphia, to double that.

Even if snow projections fall short, it is likely to be a rough season for dune-challenged New Jersey beaches, and the wintry threats should be frequent enough to keep the salt trucks busy.

Worldwide, it has been a wild fall, featuring a record heat wave in Australia, an October snow blitz in North America followed by an astonishing melt, and high-energy, beach-denuding coastal storms, not to mention a teeming climate scandal.

A misbehaving El Niño already is a major player in juicing up the storm track, meteorologists say. During El Niño, surface water over thousands of square miles of the equatorial Pacific becomes abnormally warm. That generates strong upper-air winds that can kick-start storms that form in the Gulf of Mexico and transform into Atlantic coastal storms.

What was a weak El Niño blew up suddenly in late October, and is expected to maintain moderate strength well into the winter.

"We've popped big snowstorms in the middle of El Niño winters," said David Robinson, a Rutgers University professor who is the New Jersey state climatologist.

"This will keep us on our toes," said John Bolaris, the Fox29 meteorologist.

More elusive is the fate of the North Atlantic Oscillation, or NAO, which is critical to the cold-air supply necessary for snow.

It is measured by an index of air pressure - the weight of the atmosphere - at stations near Greenland and Portugal. When pressure near Greenland is higher, the index is said to be "negative," and the Eastern United States and Western Europe tend to get cold. The reverse is true when it is positive. It tends to be milder in the Northeast and Europe.

Although he didn't call it that, Leif Eriksson was well aware of the NAO, said Mark Serreze, director of National Snow and Ice Data Center at the University of Colorado. Eriksson, who spent a lot of time commuting on the ocean, observed that when it was pleasant in Greenland it was nasty in Europe, and vice versa.

As far as anyone knows, the Vikings did not rely on computer models to forecast the NAO phase, as meteorologists do today. Unfortunately, those NAO forecasts are unreliable beyond 10 days, and it switches phases over periods of days and weeks.

Starting about 1970, the NAO was positive more often than negative, said Serreze, perhaps a by-product of worldwide warming, but it has been more variable in recent years.

"We don't really understand what's driving it," said Yochanan Kushnir, senior research scientist at the Lamont-Doherty Earth Observatory in Palisades, N.Y.

Computer models have revolutionized short-term forecasting by solving complex equations. Over time, small errors make predictions less reliable, and the calculations don't work over weeks and months. So the long-ranger has to rely on correlations and recognize patterns.

Judah Cohen, a scientist at AER Inc. in Massachusetts, has found a connection between October snow cover in Siberia and winter in the United States. He went with cold in the East this year based on a late-breaking October snow blitz in Eurasia.

"It came down to my gut, and my indicators," he said, adding it was a tough call because November was so warm in the East. Robinson said it was one of the warmest Novembers on record in New Jersey.

In Philadelphia, the temperature hasn't hit freezing since Nov. 7, and before yesterday had gone above 50 every day for a month.

Winterphobes need not despair. Given the record of seasonal forecasting, warmth might well return and dominate until Easter. Last year, for example, Accu-Weather called for a cold December and February and a mild January. January was cold, and December and February were mild. NBC10's Glenn Schwartz went too high on the snow.

But Accu-Weather's Joe Bastardi said he was confident he wasn't overdoing his snow forecast of up to 30 inches for Philadelphia.

"If winter turned out colder and snowier, it wouldn't surprise me," he said. "I would be surprised if it turned out milder and less snowy."

EndText