The US northeast was battered by heavy snow and strong winds Thursday as a mighty storm carved a violent arc across several states, killing more than a dozen people and snarling holiday travel.

More than 3,000 flights have been cancelled since Christmas Day including 746 on Thursday, as the storm wreaked havoc from the Gulf of Mexico to the Great Lakes before heading northeast, according to tracker FlightAware.

In New York City, high winds caused major air traffic delays: 186 flights were cancelled outright at the three major airports -- Kennedy, LaGuardia and Newark.

"Winter weather has arrived for many parts of the state, so as a precaution we have opened the emergency operation center to coordinate response efforts using all state and local resources," New York governor Andrew Cuomo said.

New York Mayor Michael Bloomberg used residents still without power two months after deadly superstorm Sandy slammed into the city in October to seek refuge in emergency shelters.

Although the storm was winding down late Thursday, a warning for heavy snow remained in effect overnight in New Hampshire and western Maine, the National Weather Service said.

The storm was departing the region, the government forecasters said, "but not before dumping another six to eight inches (15 to 20 centimeters) of snow over portions of Maine."

So far, the heaviest snowfall has been recorded in northern New York, with 16 inches (40 centimeters) on the ground in the town of Edwards, near the border with Canada.

And a new storm was already looming, forecast to hit portions of New England, the mid-Atlantic, and the Ohio valley in the last weekend of 2012, according to forecasters at Accuweather.com.

The building storm was predicted to bring more snow, including to regions that only got rain in the first onslaught, the forecasters said.

In Canada, dozens of planes were grounded in Toronto, Ottawa and Montreal due to the wintry weather, with 18 inches of snow expected in the southern part of Quebec province.

Earlier in the week, nearly three dozen tornadoes were reported in the southern US states of Texas, Louisiana, Alabama and Mississippi.

More than 200,000 people lost power in Arkansas, Mississippi and Texas, and Entergy, the regional utility company, warned Wednesday that it could take crews up to a week to restore electricity in all areas.

The governors of both Mississippi and Alabama have declared states of emergency.

In Indiana, authorities dispatched nearly 600 trucks to clear highways and smaller state roads, and advised travelers to stay home if possible or else leave themselves extra time.

The storms have claimed at least 13 lives -- three in Arkansas, two each in Oklahoma, Indiana and Virginia, and one each in Louisiana, Ohio, Pennsylvania and Texas -- according to an AFP tally of official and media reports.

Seven dead as US storm snarls post-Christmas travel
Chicago (AFP) Dec 27, 2012 - A massive Christmas storm that whipped up tornadoes, ice and snow from the Gulf of Mexico to the Great Lakes has killed at least seven people and grounded more than 2,000 US flights.

The storm snarled holiday travel as people were warned to stay home rather than brave the strong winds, freezing temperatures and treacherous roads.

The National Weather Service warned of "dangerous travel conditions due to snow and ice covered roads" and said the weight of ice and snow could knock down power lines and trees.

Already, more than 200,000 people were without power, with tens of thousands of holiday travelers stranded across the country.

The weather service forecast up to 18 inches (46 centimeters) of snow from New York state up to Maine and warned of freezing rain, tornadoes and severe thunderstorms all the way down to the Carolinas.

Areas in the Rocky Mountains were also set to get about a foot of snow from a second storm system on Wednesday.

Albion, Illinois had already recorded 18.3 inches (47 centimeters) of snow by Wednesday afternoon while parts of Pennsylvania had recorded as much as half an inch of freezing rain as the storm continued to pound the region.

The Indiana state police said it had responded to 159 crashes near Indianapolis -- many of them with multiple vehicles -- in just the first few hours of the storm.

More than 1,500 US flights had been canceled by Wednesday evening, after 536 were grounded on Tuesday, according to flight tracker FlightAware.

Another 276 were already called off for Thursday.

"The biggest factor on both coasts is high winds and winds not aligned with runways," FlightAware chief Daniel Baker said.

"This causes significant capacity constraints that lead to long delays and cancellations."

The National Basketball Association meanwhile postponed a Wednesday night game in Indianapolis between the Indiana Pacers and the Chicago Bulls, saying it would be rescheduled.

Scores of homes and businesses were damaged Tuesday after 34 tornadoes were reported in the southern US states of Texas, Louisiana, Alabama and Mississippi.

James Bowman said he was sitting in his living room when a sudden wind rattled his rural Texas home Tuesday afternoon.

"The inside of the living room started falling down, so I just sat there in the recliner and then it didn't last but just a few seconds -- then it stopped," Bowman, who was alone at the time, told KTRE news.

"I just thank God that I wasn't hurt and the walls and stuff didn't fall in on me."

The governors of both Mississippi and Alabama have declared states of emergency.

More than 200,000 people remained in the cold and dark Wednesday after the storm knocked down power lines in Arkansas, Mississippi and Texas.

The regional utility company said it was bringing in outside crews to help, but it could be a week before service was fully restored.

"Road conditions are making travel very dangerous and slow," Entergy said.

"In addition, the threat of falling trees and tree limbs poses a substantial risk to our crews who are working to restore power as quickly as safely possible."

Two children were killed after their mother lost control of her vehicle on an icy road in Arkansas on Christmas Day, the state police said.

Another person was killed in the state early Wednesday as a result of the storm, the Arkansas emergency management service said.

A dozen people were hurt in a 21-vehicle pileup caused by icy roads in Oklahoma City that started when a truck jack-knifed on a major interstate and oncoming cars were not able to stop on the icy roadway, the Oklahoman reported.

Two women were killed in separate crashes in the state on Christmas Day, the state highway patrol said.

A man was killed in rural Louisiana when a tree hit his home on Christmas Day, and a Texas man died in similar circumstances in a Houston suburb, local media reported.