Spaghetti plots were first used to track routing through factories.
The original idea was practical rather than meteorological: draw the paths taken by people, materials, or products through a workplace. When all those routes are placed on a floor plan, the lines can resemble strands of spaghetti. The visual makes unnecessary backtracking, crossings, and long walks easy to spot.
In manufacturing and lean operations, this kind of spaghetti diagram helps analysts redesign layouts and shorten movement. A factory may discover that a component repeatedly travels between distant machines, or that workers cross the same area many times. Relocating equipment or changing the sequence of operations can reduce wasted time and energy.
The method later spread to other settings. It can map office processes, transportation, patient movement, animal migration, or the path of a mortgage application through departments. Meteorologists also use the name for forecast plots, but that is a later application, not the origin. In that context, the lines represent different forecast solutions rather than routes through a building.