What to know about the wild storms hitting the US

Severe storms and flash flooding across the US Midwest and South have killed at least 16 people, with Kentucky particularly hard hit.
Extensive flooding has closed hundreds of roads and submerged parts of Hopkinsville, Kentucky. Tennessee also experienced significant devastation.
The storms have spawned tornadoes and caused widespread travel disruptions, with hundreds of flights canceled or delayed.
The severe weather is attributed to a combination of warm temperatures, atmospheric instability, strong wind shear, and moisture from the Gulf.
Forecasters predict further severe weather, including a catastrophic risk of flash flooding in several states, and warn of potential disruptions to shipping and supply chains.