Its a straight line wind event that develops along a dry line. Derechos act like a wall of storms arm to arm, working together, but never spinning into supercells. Because they all compete for the same sources of warm moist air (inflow) at the same time. The tornadic mesocyclonic storms are typically alone in the sky, spinning like a top. When all the storms fire at the same time, in close proximity, they cant spin. In turn, they form a wave of energy like a breaker on a reef. But it never breaks. Eventually, the center of the storm complexes cant outrun the strong northerly winds coming behind, and like a flimsy piece of sheet metal, it bends from the center out, (bow echo). The area that is between the troughs to the north and south of this "bow" is where the strongest winds are. The instense rainfall drags the real winds from up high down low with the rain shaft as gravity takes over... similar to a microburst, but different dynamics at play.
Once the "bow" has formed, it spreads out like a ripple and it will continue until it runs out of daylight. The sun is the engine, the storms feed off the humid warm air we dread. Its their gasoline. Once the sun sets, the surface of the earth cools and convection slows to a halt.
Hope that explains it well enough.
jk but scared stiff is the word
