A destructive line of thunderstorms is sweeping through the mid-South this afternoon, bringing with it incredibly strong straight-line winds in excess of 80 MPH. The system will come dangerously close to Memphis by 2:00PM CDT, and will enter northern Mississippi and Alabama over the next few hours.
The above radar image from 1:34 PM CDT is two different products of the same view. The left image is base reflectivity, showing precipitation, and the right image is the base velocity, showing winds (in MPH) about 800 feet above ground level. Radar is showing winds just above the surface between 80 and 95 MPH, and these could easily translate to the ground.
The complex is responsible for producing wind damage from southeastern Kansas through northeastern Arkansas, with several spotters reporting 75-80 MPH winds along its path.
The system will continue to produce destructive winds in excess of 80 MPH as it moves through the northern Memphis metro area into southern Tennessee. If it continues on its current trajectory, it will pass through extreme northern Mississippi and move into northern Alabama over the next few hours, but there's a chance that it could take a more easterly route and continue through central Tennessee.
The storms are part of what's known as a mesoscale convective system (MCS), or a highly organized line of thunderstorms that develops an internal structure that allows it to produce extremely strong winds that can sometimes reach 100+ MPH. If an MCS lasts long enough and produces a large amount of damage over nearly 250 miles, it can be considered a derecho. Even if a storm isn't called a derecho, it can still be incredibly dangerous.
If you live in the path of the storms, make sure loose objects outside are secured or brought indoors, and that you are indoors yourself when the storms hit. This kind of thunderstorm hits like a wall of wind and can easily knock over trees, power lines, do structural damage, and send debris flying around.
[Images via GOES and Gibson Ridge]
Update 2:45 PM CDT: A new severe thunderstorm watch is in effect for the counties outlined in blue. The threat with these storms is strong straight-line winds with "scattered significant gusts to 80 MPH likely," according to the Storm Prediction Center. A few tornadoes and hail up to 2.00" in diameter (larger than a golf ball) are also possible.