Deadly path of ‘bomb cyclone’

FIFTY-EIGHT million Americans are in the path of a brutal winter storm that has battered the east coast, bringing snow and freezing temperatures the likes of which some cities haven't seen in nearly 30 years.

The harsh conditions have been sparked by a bombogenesis blizzard - or a "bomb cyclone" - which occurs when a sharp drop in atmospheric pressure greatly intensifies a storm.

At least 17 people have died as a result of the severe conditions from Texas to New England, including a 96-year-old woman with dementia who was found frozen in a playground in Michigan wearing only a dressing gown and slippers.

Florida's capital Tallahassee received its first snow in nearly three decades on Wednesday, and parts of Georgia and South Carolina received their heaviest falls since the 1980s.

Meanwhile, New York City has been battered with heavy snow and gusty winds that have played havoc with commutes and shut down schools on Thursday.

As much as 20cm (eight inches) of snow was expected to fall across the city.

New York governor Andrew Cuomo declared a state of emergency and urged people not to drive.

"Unless it is essential for you to be out on the roads, you should not be," Mr Cuomo said.

"It becomes a question of common sense for New Yorkers."

States of emergency have also been declared for Florida, Georgia, North Carolina and Virginia.

The storm is now racing north, causing as many as 3000 flights to be cancelled.

"It's sort of akin to a hurricane travelling up the coast," Weather.US meteorologist Ryan Maue told AP.

WHAT IS A 'BOMB CYCLONE'?

Move over, "polar vortex". We have a new weather-nerd term to get our mittens on.
The term "bomb cyclone" turned up in a story in the Washington Post on Tuesday, which very quickly took on a life of its own on social media.

Despite the explosive terminology, it's not as scary as it sounds.

Based on the technical term "bombogenesis", a bomb cyclone is triggered when a storm's barometric pressure drops by 24 millibars in 24 hours - which greatly strengthens the storm.

The happen as many as 50 times a year, but mostly over the ocean.

"Bombogenesis is the technical term. Bomb cyclone is a shortened version of it, better for social media," said Mr Maue, who helped popularise "polar vortex" in 2014.

"The actual impacts aren't going to be a bomb at all.

"There's nothing exploding or detonating."

The worst of this storm will stay out to sea, but bitterly cold wind gusts of about 100km/h are likely to be more dramatic than snowfalls as the storm barrels northwards.

"We use the term bomb," University of Oklahoma meteorology professor Jason Furtado told AP. "We know what it means, but I do think it gets a little hyped up."

- with wires