The corridor of atmospheric conflict, and with it a swath at risk of flooding rain, will shift slowly southward through Sunday night. Thus, the area threatened with excessive, flooding rain will span the mid-south from eastern Oklahoma and northeastern Texas east to the southwestern Appalachian highlands.

A few of the bigger cities here will be Little Rock, Ark., Memphis, Tenn., Nashville, Tenn., and even as far west as Dallas-Fort Worth, Texas.

Widespread rainfall of 1-3 inches will trigger urban and small stream flooding with marked rises on rivers. In areas of heaviest rainfall, locally 5-6 inches by Monday morning, flooding may be serious enough to necessitate evacuations.

For drivers, this guideline is potentially a lifesaver: do not drive through floodwaters. A foot of flowing water can sweep a car off the road.

Story by AccuWeather.com Senior Meteorologist Jim Andrews.