Albany

Now might be the time to make sure the furnace is in good shape, as a Polar Vortex that has brought two bone-chilling winters to the Northeast this decade will be bringing an Arctic blast into the Capital Region next week.

By Tuesday night, temperatures are predicted to plummet into the teens, ushering in a cold snap expect to last at least through the week before Christmas. So snow gun operators at ski resorts should be able to make plenty of snow for the busy season between Chrismas and New Year's Day.

"A snap of cold like this is exactly what we are looking for. We will definitely be taking advantage of it," said Katie Vogel, marketing director of Jiminy Peak, in the Berkshire Mountains of Massachusetts.

This cold blast is being caused by a shift in the Polar Vortex, which are high-altitude winds that circle above the Arctic, said Andrea Lang, an assistant professor of atmospheric and environmental science at the University at Albany.

The vortex normally keeps the coldest Arctic air penned in, but in recent years the vortex has been weakening, causing it to sometimes become misshapen, which can allow warm air to move farther north than normal and super-cold air to flow farther south than normal.

"This kind of change in the vortex can happen in short bursts," she said. "But this pattern looks like it will be locking in a while." How long is still difficult to predict, she added.

The vortex is influenced by the temperature difference between the Arctic, which in recent decades has been warming at twice the global average, and more temperate regions to the south. Arctic sea ice has been shrinking for several decades as temperatures climb.

Last month, Arctic sea ice was at its third-lowest level for that month based on satellite records dating to 1979, according to the National Snow and Ice Data Center. The extent of ice was about 480,000 square miles less than the average for November from 1981 to 2010.

As the Arctic warms and loses more sea ice, that temperature difference with southerly regions has been narrowing, which causes the jet stream to weaken and wobble. This weakening also allows high-pressure systems to remain in place longer.

That wandering vortex is what caused extreme winter conditions in the Capital Region and the Northeast in 2013 and 2014.

Currently, an unusual high pressure system over the West Coast has begun to push warmer air against the vortex as far north as Alaska , which in turn is pushing the misshapen vortex more to the south in the eastern part of the country, which will let the Arctic air flow in, Lang said.

Starting next week, the Capital Region will be colder at night than the Alaskan city of Anchorage, with low temperatures in that city running about 10 degrees higher than in Albany, according to forecasts.

Last month, the National Weather Service warned of an Arctic blast, calling it a "major longwave pattern change" that would cause an outbreak of "below to much-below temperatures" in the eastern third of the U.S. "through at least mid-December."

And this week, the Albany office of the Weather Service sounded a similar alarm in one of its forecasts: "The potential for a strong Arctic air mass arrives by the middle of next week."

But whatever the vortex does this season, consumers should remain snug in their homes, as supplies of home heating fuels, particularly propane, are plentiful, according to a recent survey by the New York State Energy Research and Development Authority.

In New York, about a quarter-million homeowners, primarily in rural areas, heat with propane. In 2013, 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.

Propane stocks in New York have been steadily rising this fall, and by the end of November were about 5 million barrels, compared to about 4 million barrels this time last year. However, propane prices are about 20 percent higher statewide to start this winter compared to a year ago.

In the Capital Region, propane is averaging about $3 a gallon, compared to $2.58 a year ago, according to NYSERDA figures.

The state's electrical grid also is ready for any cold snap, according to the New York Independent System Operator (ISO), which oversees the grid.

Planners expect that state consumers will need about 24,400 megawatts of power this winter, which is less than the record set during the winter of 2014, when more than 25,700 megawatts were used.

Overall, about 38,600 megawatts can be generated statewide. A megawatt is enough power to maintain about 1,000 average homes.

More on the Polar Vortex On the Web 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 See More Collapse

Last month, ISO Vice President Wes Yeomans forecast that power supplies are adequate even if there is a complete loss of natural gas, since about half of the state's power plant capacity can operate on oil if natural gas is not available.