GOES image: parallel trains of clouds. What to make of them?
The species is Stratocumuls undulatus Sc un.

They can form for example when cold, dry air moves over a warmer ground layer. A sharp wind shear at the boundary layer blows these waves. (Wikipedia on Sc).

They are not to be confused with Sc radiatus or yet another form, the so-called "cloud streets", which form along the wind direction.