Science Says: Get used to polar vortex outbreaks

Polar vortex [image credit: NASA]

H/T Phys.org
Changing polar vortex patterns and wavy jetstreams – do they suggest solar magnetic changes as sunspots decline, or another 0.01% of trace gases in the atmosphere, or something else? Much scientific head-scratching, although research has been going on for a while.

It might seem counterintuitive, but the dreaded polar vortex is bringing its icy grip to parts of the U.S. thanks to a sudden blast of warm air in the Arctic, writes Seth Borenstein.

Get used to it. The polar vortex has been wandering more often in recent years.

It all started with misplaced Moroccan heat. Last month, the normally super chilly air temperatures 20 miles above the North Pole rapidly rose by about 125 degrees (70 degrees Celsius), thanks to air flowing in from the south. It's called "sudden stratospheric warming."

That warmth split the polar vortex, leaving the pieces to wander, said Judah Cohen, a winter storm expert for Atmospheric Environmental Research, a commercial firm outside Boston.

"Where the polar vortex goes, so goes the cold air," Cohen said.

By Wednesday morning, one of those pieces will be over the Lower 48 states for the first time in years. The forecast calls for a low of minus 21 degrees (minus 29 Celsius) in Chicago and wind chills flirting with minus 65 degrees (minus 54 Celsius) in parts of Minnesota, according to the National Weather Service.

The unusual cold could stick around another eight weeks, Cohen said.

"The impacts from this split, we have a ways to go. It's not the end of the movie yet," Cohen said. "I think at a minimum, we're looking at mid-February, possibly through mid-March."

Americans were introduced to the polar vortex five years ago. It was in early January 2014 when temperatures dropped to minus 16 degrees (minus 27 Celsius) in Chicago and meteorologists, who used the term for decades, started talking about it on social media.

This outbreak may snap some daily records for cold and is likely to be even more brutal than five years ago, especially with added wind chill, said Jeff Masters, meteorology director of the private weather firm Weather Underground.

When warm air invades the polar region, it can split the vortex or displace it, usually toward Siberia, Cohen said. Recently, there have been more splits, which increase the odds of other places getting ultra-cold, he said.

Pieces of the polar vortex have chilled Europe, Siberia and North America this time. (It's not right to call the frigid center of cold air the polar vortex because it is just a piece or a lobe, not the entire vortex, said University of Oklahoma meteorology professor Jason Furtado.)

When the forces penning the polar vortex in the Arctic are weak, it wanders, more often to Siberia than Michigan. And it's happening more frequently in the last couple decades, Furtado said.

A study a year ago in the Bulletin of the American Meteorological Society looked at decades of the Arctic system and found the polar vortex has shifted "toward more frequent weak states."

Continued here.

from Climate Change Skeptic Blogs via hj on Inoreader http://bit.ly/2FWds5E