Tornado outbreak in the South kills 5 in Alabama

A tornado killed at least five people and injured several others in Calhoun County, Alabama, the county's coroner confirmed Thursday evening, according to NBC-affiliate WVTM13.

The big picture: A major tornado outbreak featuring high-end, "violent" tornadoes is underway across the South, with cities including Birmingham and Nashville at risk of severe weather.

The latest: The National Weather Service's Storm Prediction Center has issued a rare category 5 out of 5, "high risk" for severe weather, including potentially "violent" tornadoes, mainly for northern Alabama.

• A large tornado struck in or close to Brent and Centreville, Alabama, around 5 p.m. local time, prompting the Weather Service to issue a "tornado emergency" and warn of potentially "catastrophic" damage.
• Radar showed a large amount of debris from this tornado lofted into the atmosphere in what is known as a "debris ball" signature. "What you are seeing is graphic violence," said Birmingham TV meteorologist James Spann as he described the radar shown to viewers.

The National Weather Service issued a "particularly dangerous situation" tornado watch for much of Mississippi and Alabama through 8 p.m local time. The watch text indicates that "numerous tornadoes and several intense tornadoes" are expected in this area, along with storms containing very large hail and damaging straight-line winds.

• The watch area includes Jackson and Tupelo, Mississippi, and Birmingham, Alabama.
• Another tornado watch is in effect for southern Illinois, southern Indiana, western and central Kentucky, southeast Missouri, northeastern Mississippi and western and middle Tennessee until 11 p.m.
• This watch area includes Nashville, Tennessee, as well as Paducah, Kentucky.
• Earlier, one long-lasting severe thunderstorm tore a path across Alabama, causing significant damage.
• A large tornado from this storm passed south and east of Tuscaloosa at about 12:30 p.m. local time, prompting a rare "particularly dangerous situation" tornado warning.
• That storm then moved northeast toward Birmingham where it spawned another tornado southeast of Birmingham, prompting the National Weather Service to issue a tornado emergency.
• This tornado damaged Spann's home while he was broadcasting from the TV studio. He told viewers his family was ok, though his home sustained significant damage.

Details: The stage continues to be set for a dangerous evening in the South as warm, humid air flows north from the Gulf of Mexico, just as a pinwheeling area of low pressure at upper levels of the atmosphere moves in from the west. Fronts associated with these features are setting off multiple rounds of severe thunderstorms.

• Winds blowing at different speeds and/or directions with height are ensuring that storms have the propensity to rotate, putting large hail and tornadoes on the list of threats.
• The storms developed first in central to northern Alabama and Mississippi on Thursday afternoon, with the threat shifting north into Tennessee and parts of the Ohio Valley this evening into the overnight.

Between the lines: Severe weather in this region can be especially deadly due to the housing types that are prevalent here, including large numbers of mobile homes.

• With thick tree cover, hills and winding roads, tornadoes that can be wrapped in areas of heavy rain can be harder to spot than twisters in the Great Plains.
• Nighttime tornadoes are especially deadly, in part due to the difficulty of warning residents and ensuring they reach safe shelters in time. This severe thunderstorm outbreak is forecast to continue into the evening and possibly the overnight hours.