Yet another nasty tornado outbreak is getting under way across the south-central U.S., with tornadoes already sighted in northern Texas, southeastern Oklahoma and southwestern Arkansas.

This is a particularly dangerous situation with a risk of large, long-track tornadoes, especially from far northeastern Texas and northwestern Louisiana into Arkansas, northwestern Mississippi, western Tennessee, western Kentucky, southern Illinois and southern Missouri tonight.

Little Rock, Ark., Paducah, Ky., Carbondale, Ill., Cape Girardeau, Mo., Memphis, Tenn., Batesville, Miss., Shreveport, La., and Mt. Pleasant, Texas are included. The thunderstorms will be moving west to east across these areas this evening and overnight. As AccuWeather.com Senior Meteorologist Kristina Pydynowski pointed out, another major tornado outbreak is expected to erupt in many of these same areas late Tuesday into Tuesday night. [ accuweather ]

People in the path of these thunderstorms need to seek safe shelter immediately if a tornado or severe thunderstorm warning is issued. The safest place to be during a tornado is in the most interior room of the lowest level of a sturdy building. Mobile homes are not safe.

Tornadoes have already been spotted near Big Fork, Ark., Broken Bow, Okla., and Stephenville, Chalk Mountain, Cleburne, Itasca, Avalon and Troup, Texas. In Broken Bow, trees were reportedly downed onto roads and homes with widespread power outages resulting.

In addition to tornadoes, thunderstorms will be capable of producing hail larger than golf balls, damaging winds that can down trees, power lines and cause property damage and flooding downpours.

Some places have picked up nearly 10 inches of rain over the past few days with flooding already under way. Many weather-related deaths happen when people attempt to cross a flooded roadway and get swept away. Never attempt to cross a flooded roadway; always turn around and find an alternate route.

Severe thunderstorms have also been erupting along and south of a frontal boundary stretching from central Missouri through northern Pennsylvania with large hail and wind damage reported.

St. Louis, Mo., which was pummeled by a tornado that even hit the city's airport over the weekend, is at risk for these damaging thunderstorms tonight.

A few tornadoes were also sighted in western Tennessee with some of these thunderstorms earlier in the afternoon.