US north-east braces for 'historic' snowstorm

The north-east US coast is braced for a big snowstorm that has already caused hundreds of flight cancellations.

The storm is set to cause power cuts and transport chaos as it arrives from the Great Lakes and brings blizzards to parts of New England on Friday.

It is expected to peak on Saturday morning east of Cape Cod.

Schools have already been closed in Boston, where sustained strong winds are set to exacerbate heavy snowfall - as much as two feet in some areas.

The National Weather Service said the combination of two weather systems from the polar and subtropical jet streams would produce a "potentially historic" storm, with weather warnings extending from New Jersey to Maine.

Winds of up to 35mph (55km/h) with significantly stronger hurricane-strength gusts were expected to create deep drifts.

Airlines have already cancelled hundreds of flights across the region.

In Boston, Mayor Thomas Menino urged businesses to consider allowing staff to stay home to reduce the risk of commuters getting stranded.

"We are hardy New Englanders, let me tell you, and used to these types of storms," said Mr Menino.

"But I also want to remind everyone to use common sense and stay off the streets of our city. Basically, stay home,"

In New York, where memories of October's Hurricane Sandy are still fresh in the mind, the famous Staten Island ferry has had its schedule reduced. While schools remain open for now, residents are being advised to prepare for the worst.

"Due to potential power outages and transportation difficulties, New Yorkers are advised to stock up on potential supplies, including medicine," said the city's mayor, Michael Bloomberg.

With up to a foot of snow expected over the next two days, Mr Bloomberg said snow ploughs and 250,000 tonnes of salt were being readied for use.

Storm system threatens to bring high winds, tornadoes to 10 states

A storm system stretching from Texas north to Michigan threatens to bring "widespread damaging winds and several tornadoes" to parts of 10 states, the National Weather Service said Tuesday.

"An increasing threat for severe thunderstorms will occur through tonight in advance of a strong cold front moving across the central United States," the weather service's Storm Prediction Center said. "The most intense thunderstorms are anticipated late this afternoon and especially into the overnight hours tonight across parts of the lower Ohio Valley, mid-South and lower Mississippi Valley."

States threatened by what the agency called a moderate risk of severe weather are Arkansas, southern Illinois, extreme southwestern Indiana, western Kentucky, western Tennessee, southern Missouri, northern Louisiana, northern Mississippi, southeastern Oklahoma and northeastern Texas, the agency said.But severe storms are possible along a line from the southern Great Lakes to the Louisiana coast, the Storm Prediction Center said.

Tornado watches were up Tuesday afternoon for portions of Arkansas, Kansas, Missouri, Illinois, Oklahoma and Texas.

Those storms could be at their most dangerous late Tuesday night into Wednesday morning, CNN meteorologist Sarah Dillingham said.

Extreme weather and a changing climate

Even outside the areas most at risk for tornadoes, wind gusts could reach 80 mph in some areas -- enough to bring down trees and power lines, she said.

On Wednesday, the threat shifts farther east, with parts of Alabama, Georgia, Tennessee, Kentucky, South Carolina, North Carolina, Virginia and West Virginia at moderate risk of severe weather, including damaging winds and isolated tornadoes, the Storm Prediction Center said.

After the severe weather, a cold-weather system could bring snow and freezing rain to the Midwest, beginning Wednesday, and the threat of extremely cold weather in the northern Plains states and Upper Midwest, particularly on Thursday.