The National Weather Service had earlier said the combination of two weather systems from the polar and sub-tropical jet streams would produce a "potentially historic" storm.

BBC: Snowstorm batters north-east US and Atlantic Canada

In a report in the journal Nature, US researchers say they have worked out how black holes emit jet streams of particles at close to light speed.

BBC: Black holes reveal more secrets

It will make its way into the jet stream and come the the US. The same jet streams that carried Japanese baloon bombs to the US in WW2.

FORBES: Coal Imports Bolster India's Private Ports

One possibility is that the jet streams that normally hit the west coast straight on will instead swing up into Alaska and dive down the coast, bringing along cold arctic winds with it.

CNN: La Nina spawns extreme weather

But keen viewers everywhere used several live streams of the event on the internet, including a feed from the Jet Propulsion Laboratory at Nasa.

BBC: Asteroid 2012 DA14 in record-breaking Earth pass