AccuWeather.com

By Meghan Evans, Meteorologist

Apr 4, 2011; 7:12 AM ET

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Courtesy: Photos.com

An extensive line of severe thunderstorms will ignite along a powerful cold front today, threatening communities from the Ohio and Tennessee valleys to the western Gulf Coast.

The cold front triggering the severe storms early in the week is the same one that brought the threat of damaging storms from Dallas to Chicago on Sunday night.

With the threat of severe weather also expected to expand to the East Coast through tonight, this is forecast to be the biggest outbreak of severe weather so far this spring. All together, a quarter of the country may be impacted.

Severe Storm Threat Today

Some cities at risk for getting hit by severe storms today include: Houston, Texas, New Orleans, La., Jackson, Miss., Nashville and Memphis, Tenn., Louisville, Ky., Cincinnati and Columbus, Ohio, and Pittsburgh, Pa.

Damaging wind gusts over 60 mph will be the biggest and most widespread concern with the thunderstorms. Hail the size of quarters and larger and a few tornadoes could be produced by the strongest thunderstorms that erupt.

The winds could topple trees and power lines, while the largest hail can break windows.

The worst of the thunderstorms, including the greatest threat for tornadoes, are expected to fire up from eastern Kentucky to northern Mississippi.

Flash flooding will be a concern with the heaviest downpours. Motorists are urged to avoid driving across roadways with water over them.

Blinding downpours can also slow travel along major interstates, including I-10, I-20, I-40 and I-70.

Severe Storm Threat Tonight

Potentially life-threatening and damaging storms will continue to head eastward overnight. Areas from northern Florida through the southern parts of Pennsylvania and New Jersey will be in the path of the thunderstorms.

Cities that may endure a pounding from damaging storms overnight include: Pensacola and Jacksonville, Fla., Atlanta, Ga., Charlotte and Raleigh, N.C., Washington, D.C., and Philadelphia, Pa.

The cold front triggering the severe thunderstorms will continue to push eastward off the Southeast coast and southward across central and southern Florida on Tuesday. After tapering off along much of the Southeast Coast during the morning, showers and thunderstorms will erupt over central and southern Florida for much of the day.

Tampa and Orlando may have stormy weather all day, while the main threat in Miami will be later in the day.

Locally strong winds, isolated waterspouts and tornadoes, and flash flooding cannot be ruled out, but the main energy of the storm system will be too far to the north for organized severe weather.

AccuWeather.com meteorologists will continue to closely monitor the potential for severe weather in Florida, which was hammered by destructive storms over the last couple of days of March.

"This is a very serious weather situation, and we have been issuing pinpoint severe weather warnings the past several days," said Bradley J. Mitchell, Chief Commercial Officer of AccuWeather Enterprise Solutions.

Keep checking back with AccuWeather.com for the latest on the most widespread outbreak of severe weather so far this spring.