When flooding occurs across the northern Plains and Upper Midwest, the lowerMississippi often can hold its own. That's because the Ohio River is thebiggest contributor of the water that goes into the Mississippi south of Cairo,Ill.In this case, we have a situation in which several major rivers, including theMissouri and the Ohio, will be emptying a surplus of water into the Mississippiin the days and weeks ahead. One source of the extra water is coming from allthe snow melt that is occurring across the northern Plains and Midwest. There,moderate to major flooding is already taking place. There is also a tremendousamount of water coming out of the Appalachians, the result of recent rains andrising temperatures.

Residents along the lower Mississippi need to be aware that the water levelwill be rising, and flood stage may be reached at some points in the riverbeginning this weekend. This will be a long-term event which is likely topersist for at least a few weeks into the spring.

Story by AccuWeather.com Senior Meteorologist John Kocet.