'Polar Vortex' could freeze chunks of the US
THE polar vortex that brought even the Niagara Falls to a halt in the US last winter could make a return in the coming months.
Forecasters at AccuWeather.com predicted another harsh season for north-eastern states with more ice, snow and arctic winds causing below-freezing temperatures.
In his long-range forecast, Paul Pastelok said a polar vortex would make its presence felt when it "slips down" into the region.
"I think, primarily, we'll see that happening in mid-January into February but again, it's not going to be the same type of situation as we saw last year, not as persistent," he added.
"The cold of last season was extreme because it was so persistent. We saw readings that we haven't seen in a long time: 15- to 20-below-zero readings."
Mr Pastelok was also concerned about the region from the Tennessee Valley to the Gulf Coast for "extremes" including rain, storms and "ice events".
The picture looks more average for the American Midwest, Northern and Central Plains.
Long-term forecasts are not as reliable as shorter-term predictions, meteorologists cautioned, but news that the weather may not be so extreme will be welcome to the towns and cities that were frozen to a standstill in January.
All 50 states were affected by the weather phenomenon, which froze beaches in Chicago, entire buildings in Nebraska and saw temperatures drop as low as -37C.
Polar bears at a Chicago zoo had to be brought inside and an escaped prisoner turned himself in to get out of the cold after just a day on the run.
Even Hell froze over as the polar vortex took hold, with the Michigan town experiencing freezing temperatures of -26C.
A polar vortex is a circulating pattern of strong winds flowing around a low-pressure system of cold air, which normally sits over the Arctic during winter.
If it breaks down or splits into two, it can send very cold air further south, causing extreme conditions.