Chicago, January 31
The blast of Arctic air that brought record-breaking cold, causing at least a dozen deaths and cancelling or delaying thousands of flights in the US Midwest, spread eastward on Thursday, bringing frigid misery to the Northeast.
A forecast for warmer weather by the weekend offered little comfort to those enduring icy conditions, brutal winds and temperatures as low as -34°C. “This morning is some of the coldest of the temperatures in the Midwest, and we still have some dangerous wind chills,” Andrew Orrison, a forecaster for the National Weather Service, said in a phone interview.
In Minnesota and Upper Michigan, temperatures will be at -29°C on Thursday and parts of North Dakota can expect -30F, forecasters warned. The bitter cold was caused by displacement of the polar vortex, a stream of air that normally spins around the stratosphere over the North Pole but whose current was disrupted. It pushed eastward and states including Massachusetts, New York and Pennsylvania experienced bitterly cold temperatures. It has been more than 20 years since a similar Arctic blast covered a swath of the Midwest and Northeast. The cold has caused 12 deaths since Saturday across the Midwest, according to officials and news media reports. — Reuters
What is polar vortex?
Polar Vortex is a ‘large area of low pressure and cold air surrounding the Earth’s North and South Poles’, which can become unstable during winter in the Northern Hemisphere. It’s a band
of strong winds that keep bitterly cold air locked around the Arctic region. This circulation isn’t considered a single storm or even a weather pattern as such.
Why is it affecting the US?
Occasionally, the vortex can become distorted and meander far south than normal. That instability has led to an expansion of the vortex, sending frigid Arctic air south over the continental US. “At the moment, the vortex looks like two swirling blobs of cold air, one settled over North America, the other over Eurasia,” said Jennifer Francis, the senior scientist at the Woods Hole Research Centre.
from The Tribune http://bit.ly/2CXCBIX
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