breaking news

Brightline adds safety features at crossings

Science Says: Why there's a big chill in a warmer world


Anchorage, Alaska, was warmer Tuesday than Jacksonville, Florida. The weather in the U.S. is that upside down.

That's because the Arctic's deeply frigid weather escaped its regular atmospheric jail that traps the worst cold. It then meandered south to the central and eastern United States.

And this has been happening more often in recent times, scientists say.

___

WHY IS IT SO COLD?

Super cold air is normally locked up in the Arctic in the polar vortex , which is a gigantic circular weather pattern around the North Pole. A strong polar vortex keeps that cold air hemmed in.

"Then when it weakens, it causes like a dam to burst," and the cold air heads south, said Judah Cohen, a winter storm expert for Atmospheric Environmental Research, a commercial firm outside Boston.

"This is not record-breaking for Canada or Alaska or northern Siberia, it's just misplaced," said Cohen, who had forecast a colder than normal winter for much of the U.S.

IS THIS UNUSUAL?

Yes, but more for how long — about 10 days — the cold has lasted, than how cold it has been. On Tuesday, Boston tied its seven-day record for the most consecutive days at or below 20 degrees that was set exactly 100 years ago.

More than 1,600 daily records for cold were tied or broken in the last week of December, according to the National Oceanic and Atmospheric Administration. For Greg Carbin of the National Weather Service's Weather Prediction Center, the most meaningful statistics are how last week's average temperature was the second coldest in more than a century of record-keeping for Minneapolis, Chicago, Detroit and Kansas City, third coldest in Pittsburgh and fifth coldest in New York City.

IS IT JUST THE U.S.?

Pretty much. While the United States has been in the deep freeze, the rest of the globe has been toastier than normal. The globe as a whole was 0.9 degrees (0.5 degrees Celsius) warmer than normal Tuesday and the Arctic was more than 6 degrees warmer than normal (3.4 degrees Celsius), according to the University of Maine Climate Change Institute's analysis .

WHAT'S NEXT?

The cold will continue and could actually worsen for much of the East Coast this weekend because of a monster storm that's brewing in the Atlantic and Caribbean, what meteorologists are calling a "snow hurricane" or "bomb cyclone."

But forecasters don't think the storm will hit the East Coast, keeping most of the snow and worst winds over open ocean, although parts of the Northeast are still likely to get high winds, waves and some snow.

"For the Northeast, this weekend might be the coldest of the coldest with the storm," said Jason Furtado, a University of Oklahoma meteorology professor. "We could be ending (the cold snap) with a big hurrah."

WHAT MAKES THE POLAR VORTEX MOVE?

This is an area of hot debate and research among scientists and probably is a mix of human-caused climate change and natural variability, said Furtado. Climate change hasn't made the polar vortex more extreme, but it probably is making it move more, which makes the weather seem more extreme, he said.

A recent study by Potsdam Institute climate scientist Marlene Kretschmer found the polar vortex has weakened and meandered more often since 1990, but that study focused more on Europe. Ongoing research shows that there seems to be a similar connection for more frequent Arctic cold snaps like what the U.S. is now experiencing, Kretschmer said.

HOW CAN IT BE SO COLD WITH GLOBAL WARMING?

Don't confuse weather — which is a few days or weeks in one region — with climate, which is over years and decades and global. Weather is like a person's mood, which changes frequently, while climate is like someone's personality, which is more long-term, Furtado said.

"A few cold days doesn't disprove climate change," Furtado said. "That's just silly. Just like a couple down days on the stock market doesn't mean the economy is going into the trash."

___

Follow Seth Borenstein on Twitter at @borenbears . His work can be found here .

___

This Associated Press series was produced in partnership with the Howard Hughes Medical Institute's Department of Science Education. The AP is solely responsible for all content.


Reader Comments ...


Next Up in Nation & World

10-month-old baby drowns after intoxicated mother falls asleep in tub, police say
10-month-old baby drowns after intoxicated mother falls asleep in tub, police say

A 35-year-old Melbourne Beach mother has been arrested in the drowning death of her 10-month-old baby, Brevard County authorities said. >> Read more trending news  Rosa Regina Feeney was arrested Monday and faces charges of aggravated manslaughter of a child and child neglect. Deputies said the investigation began Dec. 6 at Deangelo&rsquo...
3 sentenced in stomping that caused pregnant teen to miscarry brother’s child
3 sentenced in stomping that caused pregnant teen to miscarry brother’s child

Three members of a Texas family were sentenced to prison last week in the brutal 2013 beating and stomping of a 13-year-old relative who authorities said was raped -- and impregnated -- by her own brother.  Sharon Jones, 47, of Dallas, and two of her children, Cedric Jones Jr., 29, and Cecila McDonald, 28, pleaded guilty for their part in the...
Nelson votes to keep government running, reversing his Friday vote
Nelson votes to keep government running, reversing his Friday vote

Less than 72 hours after voting to shut down the federal government, Florida U.S. Sen. Bill Nelson and most of his Democratic colleagues softened their position on immigration Monday and supported an agreement to keep the government running through Feb. 8. Nelson — up for re-election this year and attacked by Republicans for his shutdown vote...
Schumer’s ‘cave’? Shutdown deal puts spotlight on Dem leader
Schumer’s ‘cave’? Shutdown deal puts spotlight on Dem leader

Republicans tried to make Senate Minority Leader Chuck Schumer the face of the government shutdown. Now, he’s becoming the face of the Democratic retreat. For two days, Schumer, perhaps the most powerful Democrat in Washington, succeeded in keeping his party unified in a bid to use the government funding fight to push for protections for some...
Cigarette butt leads to arrest after robbery during Hurricane Irma
Cigarette butt leads to arrest after robbery during Hurricane Irma

A cigarette butt left at a home that was burglarized during Hurricane Irma led to the arrest of a Florida woman and her alleged accomplice, sheriff officials said. Cassandra Taylor, 32, was arrested after deputies said she burglarized and ransacked a DeLeon Springs home on Billings Avenue in Volusia County last Sept. during the emergency evacuation...
More Stories