The heat and humidity of Sunday gave way to more storms along a washed out frontal boundary; moreover, what started out as isolated convection near Franklin county, quickly developed into scattered showers and storms throughout the River Valley. Take a look at the radar image above. You are looking at 2 separate outflow boundaries from a complex of storms that originally developed near Ozark.

An outflow boundary is the rain cooled air that flows away from a thunderstorm. You can think of outflow like exhaust from an engine. These boundaries are typically picked up on radar, and they look like a fuzzy curved line moving away from storms. These outflow boundaries act like mini cold fronts that help lift the warm and humid air.

This particular outflow boundary created a line of strong storms from Marble City all the way to Poteau around 5:45 p.m.