Après avoir lourdement frappé le centre des États-Unis mercredi, une puissante tempête de neige a commencé à sévir sur le nord-est du pays en fin de soirée, frappant ce secteur de forts vents, de neige et de pluie verglaçante.

Le système, qui a lourdement perturbé les déplacements pendant les Fêtes, provoqué des pannes d'électricité dans des milliers de foyers, a causé la mort d'au moins six personnes.

Des centaines de vols ont été annulés ou retardés et un nombre incalculable d'automobilistes ont été ralentis par des routes glacées ou ont abouti dans des bancs de neige.

Par ailleurs, des avertissements de blizzard ont été émis au moment où des rafales de près de 50 km/h enneigeaient les routes et les pare-brise, causant des conditions semblables à un voile blanc.

Le système, qui a engendré une série de tornades dans la région du golfe du Mexique le jour de Noël et déversé une quantité de neige historique en Arkansas, s'est déplacé vers la vallée de l'Ohio et poursuivait sa route vers le nord-est mercredi soir.

Les météorologues prédisaient entre 30 et 45 centimètres dans la région comprise entre l'ouest de l'État de New York et le Maine tard mercredi et jeudi, mais le système devait perdre de son intensité et verser un mélange de pluie et de neige non loin de la côte est. On prévoyait d'ailleurs de faibles accumulations dans des villes telles New York et Boston.

Après le passage de la tempête, les températures ont chuté radicalement, tandis que les météorologues prévoyaient que certaines parties du sud-est des États-Unis, de la Virginie à la Floride, seraient touchées par de violents orages.

«J'ai décrit ce système comme un blizzard de basse-échelle, mais c'est un peu comme parler d'un petit Tyrannosaurus Rex», a illustré John Kwiatkowski, du bureau du Service national météorologique à Indianapolis.

Le congé de la période des Fêtes signifie que de nombreux Américains échapperont aux transports chaotiques dans les prochains jours, mais ceux qui doivent se déplacer se sont fait conseiller de modifier leurs projets. La neige a été la cause d'une multitude d'accidents de la route aussi loin qu'au Maryland, vers l'est, et une vingtaine de comtés de l'Indiana et de l'Ohio ont diffusé des alertes de neige, demandant aux automobilistes de ne prendre la route qu'en cas de nécessité absolue.

Dans le centre de l'Indiana, où la neige tombait au rythme de 7,5 cm/h à certains endroits, une quarantaine de véhicules ont été incapables de gravir une côte glacée et pas moins de quatre chasse-neige ont dérapé au point de sortir de la route.

Dans l'Arkansas, deux passagers d'un véhicule qui circulait sur une autoroute enneigée sont morts quand leur voiture a traversé le terre-plein central et heurté un véhicule utilitaire sport.

Dans l'Oklahoma, deux personnes, dont une femme de 76 ans, ont été tuées mardi dans des accidents survenus sur des autoroutes. Des chutes d'arbres ont coûté la vie à deux personnes au Texas et en Louisiane.

En milieu de journée, plus de 1200 vols avaient été annulés à travers les États-Unis, selon le site FlightAware.com. Des retards de plus d'une heure ont été rapportés mercredi dans les trois aéroports de New York.

Alors que la tempête se dirige vers l'est, les responsables des autoroutes de la Nouvelle-Angleterre se préparent à affronter la situation en épandant du sel et en mobilisant les équipes de déneigement.

«Les gens achètent beaucoup de sel et de pelles aujourd'hui», a indiqué Andy Greenwood, assistant-gérant au magasin Aubuchon Hardware à Keene, au New Hampshire.

Des photos de nos collègues américains ici:
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  • The front wall of the parish hall at Trinity Episcopal Church on Dauphin Street in Mobile, Ala. was torn off by a tornado on Christmas Day, Tuesday, Dec. 25, 2012 in Mobile, Ala. The tornado hit midtown Mobile causing extensive damage to the church as well as Murphy High School. (AP Photo/AL.com, Bill Starling) MAGS OUT

  • Dauphin Street at North Carlen Street in the Midtown section of Mobile, Ala. is impassable after a tornado touched down Tuesday, Dec. 25, 2012. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/AL.com, Mike Kittrell) MAGS OUT

  • A portion of the roof of the auditorium at Murphy High School is seen laying on the ground Tuesday, Dec. 25, 2012 after a tornado hit midtown Mobile, Ala on Christmas Day. (AP Photo/AL.com, Bill Starling) MAGS OUT

  • Webb

    David Webb walks in front of Trinity Episcopal Church on Dauphin St. in Mobile, Ala. on Christmas Day, Tuesday, Dec. 25, 2012. A tornado hit midtown Mobile causing extensive damage to the church. (AP Photo/AL.com, Bill Starling) MAGS OUT

  • Patterson, McGee

    Matthew Patterson and Jenetta McGee work to tape plastic over the window of McGee's car after a tree smashed it Tuesday, Dec. 25, 2012. The tree, which is laying across South Carlen St. over a downed power line, was uprooted and knocked down by a tornado which hit midtown Mobile Christmas Day. (AP Photo/AL.com, Bill Starling) MAGS OUT

  • Firefighters go door-to-door on North Carlen Street in the Midtown section of Mobile, Ala. after a tornado touched down Tuesday, Dec. 25, 2012. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/AL.com, Mike Kittrell) MAGS OUT

  • A house in the Midtown section of Mobile, Ala. is damaged after a tornado touched down Tuesday, Dec. 25, 2012. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/AL.com, Mike Kittrell) MAGS OUT

  • A home in the Midtown section of Mobile, Ala. is damaged after a tornado touched down Tuesday, Dec. 25, 2012. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/AL.com, Mike Kittrell) MAGS OUT

  • A house in the Midtown section of Mobile, Ala. is damaged after a tornado touched down Tuesday, Dec. 25, 2012. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/AL.com, Mike Kittrell) MAGS OUT

  • A car tries to navigate down a street littered with downed tree limbs and other debris after a tornado touched down Tuesday, Dec. 25, 2012 in the Midtown area of Mobile, Ala. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/G.M. Andrews)

  • The nozzle of a gasoline pump sits on the ground after being blown from its pump after a tornado touched down Tuesday, Dec. 25, 2012 in Mobile, Ala. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/G.M. Andrews)

  • A home is damaged and its lawn is covered with debris after a tornado touched down Tuesday, Dec. 25, 2012 in Mobile, Ala. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/G.M. Andrews)

  • Downed tree limbs and other debris cover the street and sidewalk in front of an apartment building after a tornado touched down Tuesday, Dec. 25, 2012 in the Midtown area of Mobile, Ala. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/G.M. Andrews)

  • A car tries to navigate down a street littered with downed tree limbs and other debris after a tornado touched down Tuesday, Dec. 25, 2012 in the Midtown area of Mobile, Ala. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/G.M. Andrews)

  • A large tree covers the front lawn of a home after tornado touched down Tuesday, Dec. 25, 2012 in the Midtown area of Mobile, Ala. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/G.M. Andrews)

  • Residents walk down a street littered and partially blocked with downed tree limbs and other debris after tornado touched down Tuesday, Dec. 25, 2012 in the Midtown area of Mobile, Ala. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/G.M. Andrews)

  • A truck tries to navigate down a street littered and partially blocked with downed tree limbs and other debris after tornado touched down Tuesday, Dec. 25, 2012 in the Midtown area of Mobile, Ala. A Christmas Day twister outbreak left damage across the Deep South while holiday travelers in the nation's much colder midsection battled sometimes treacherous driving conditions from freezing rain and blizzard conditions. (AP Photo/G.M. Andrews)

  • In this image from video provided by WALA-TV in Mobile, Ala. a tornado touches down in Mobile on Tuesday, Dec. 25, 2012. The tornado hit some areas of downtown Mobile Tuesday, causing severe damage in the area before moving north, officials said. (AP Photo/WALA-TV) MANDATORY CREDIT: WALA-TV

  • A house in Tioga, La., is severely damaged after an apparent tornado tore through the area Tuesday, Dec. 25, 2012. (AP Photo/The Daily Town Talk, Melinda Martinez) NO SALES

  • Members of the Alpine Volunteer Fire Department and the VA Fire Department clear debris from U.S. 71 in the Tioga, La. area, after an apparent tornado tore through the area Tuesday, Dec. 25, 2012. (AP Photo/The Daily Town Talk, Melinda Martinez) NO SALES

  • Debris sits on a side street near Washington Street in Alexandria, La. after an apparent tornado tore through the area Tuesday, Dec. 25, 2012. (AP Photo/The Daily Town Talk, Melinda Martinez) NO SALES

  • Debris sits on the frontage road near I-49 in downtown Alexandria, La., after an apparent tornado tore through the area Tuesday, Dec. 25, 2012. (AP Photo/The Daily Town Talk, Melinda Martinez) NO SALES

  • A street sign is bent at a severe angle from a Christmas Day tornado as residents clean up and assess the damage Wednesday, Dec. 26, 2012 in Mobile, Ala. With only a handful of injuries and no deaths reported statewide from the storms, the head of the state's emergency response said it was difficult to fathom how the toll wasn't worse. (AP Photo/G.M. Andrews)

  • Murphy High School teacher Leland Howard tries to salvage items where his algebra classroom once stood in a temporary building at Murphy High School, Wednesday, Dec. 26, 2012, as residents clean up and assess the damage from a Christmas Day tornado Wednesday, Dec. 26, 2012 in Mobile, Ala. With only a handful of injuries and no deaths reported statewide from the storms, the head of the state's emergency response said it was difficult to fathom how the toll wasn't worse. (AP Photo/G.M. Andrews)

  • Murphy High School teacher Ryan Little looks around at the student desks and other items scattered from temporary classrooms demolished by a Christmas Day tornado at Murphy High School, as residents clean up and assess the damage Wednesday, Dec. 26, 2012 in Mobile, Ala. With only a handful of injuries and no deaths reported statewide from the storms, the head of the state's emergency response said it was difficult to fathom how the toll wasn't worse. (AP Photo/G.M. Andrews)

  • Residents and clean-up crews clear damaged trees and other debris left behind by a Christmas Day tornado Wednesday, Dec. 26, 2012 in Mobile, Ala. With only a handful of injuries and no deaths reported statewide from the storms, the head of the state's emergency response said it was difficult to fathom how the toll wasn't worse. (AP Photo/G.M. Andrews)

  • A portion of Trinity Episcopal Church's roof lies on the ground beside it as residents clean up and assess the damage from a Christmas Day tornado Wednesday, Dec. 26, 2012 in Mobile, Ala. With only a handful of injuries and no deaths reported statewide from the storms, the head of the state's emergency response said it was difficult to fathom how the toll wasn't worse. (AP Photo/G.M. Andrews)

  • This Wednesday, Dec. 26, 2012 photo shows a damaged hall at Trinity Episcopal Church as residents clean up and assess the damage from a Christmas Day tornado in Mobile, Ala. With only a handful of injuries and no deaths reported statewide from the storms, the head of the state's emergency response said it was difficult to fathom how the toll wasn't worse. (AP Photo/G.M. Andrews)

  • The roof of a damaged home rests against the side of a neighboring house as residents clean up and assess the damage from a Christmas Day tornado Wednesday, Dec. 26, 2012 in Mobile, Ala. With only a handful of injuries and no deaths reported statewide from the storms, the head of the state's emergency response said it was difficult to fathom how the toll wasn't worse. (AP Photo/G.M. Andrews)

  • Debris sits near the damaged auditorium building at Murphy High School as residents clean up and assess the damage from a Christmas Day tornado Wednesday, Dec. 26, 2012 in Mobile, Ala. With only a handful of injuries and no deaths reported statewide from the storms, the head of the state's emergency response said it was difficult to fathom how the toll wasn't worse. (AP Photo/G.M. Andrews)

  • Winter Storm Kentucky

    Motorists travel slowly on a snow-covered Interstate 24 during a winter storm Wednesday, December 26, 2012, in Paducah, Ky. The storm dumped several inches of snow making travel hazardous. (AP Photo/Stephen Lance Dennee)

  • Floodwaters cover Terry Road near U.S. 80 during storms on Christmas Day, Tuesday, Dec. 25, 2012 in Jackson, Miss. Heavy rain caused flash flooding on many of the city's streets. (AP Photo/The Clarion-Ledger, Greg Jenson)