Tornadoes possible as major storm hits the South

Nearly 140 million Americans from the Rockies to the Northeast are under alert for dangerous weather this weekend due to a powerful storm taking shape in the central U.S. on Saturday.

Dangers include a severe weather outbreak and flash flood threat across the South; near blizzard conditions from the Plains to the Upper Midwest; and strong, damaging winds from Texas to the Northeast.

The complex system brought 3 to 4 feet of snow in Arizona and over 7 inches of rain in Alabama. As of early Saturday morning, Nashville, Tennessee, had recorded 11.5 inches of rain, making it the second-wettest February on record.

The storm system was bringing snow across the High Plains in New Mexico and Colorado on Saturday morning, as well as snow across parts of the Upper Midwest. High resolution forecast models are showing that locally 2 to 4 inches of rain could fall across parts of Tennessee and Mississippi during the morning hours of Saturday.

The storm will intensify and organize Saturday as it quickly slides off to the east. While blizzard conditions will spread across the Plains and into parts of the Midwest, the greatest concern will be a developing severe weather outbreak in the South. Models show supercells developing sometime during the early afternoon hours across the Mississippi River Valley.

Those supercells will head east, likely becoming quite intense during the early evening hours as they move into parts of northern Mississippi, Alabama and Tennessee.

There is a moderate risk for severe weather across northern Mississippi, southern Tennessee and western Alabama. In the moderate risk region there is the potential for dangerous tornadoes. Additionally, strong damaging winds will be likely across the entire region from Louisiana to Kentucky. Widespread wind damage is likely in this region.

This region has already seen a very wet week and additional rainfall will exacerbate flooding in the region. Flash flooding and river flooding is likely across parts of the southern U.S. through the weekend.

The storm will move into the Great Lakes and Northeast on Sunday with heavy rain heading for the Interstate 95 corridor, with some mixing for interior New England and some snow across Michigan and Wisconsin.

However, as the storm rapidly intensifies, powerful winds will slide in behind it and spread across the Midwest and into parts of the Northeast. Wind gusts of 45 to 60 mph are possible on Sunday for a large part of the region. These wind gusts will be strong enough to cause power outages and down trees. These high winds will spread into the Northeast on Sunday evening.

By Sunday night, the storm will have dumped locally 4 to 6 inches of rain across parts of the South and locally over 6 inches of snow across parts of the Midwest.