Bow Echo


A “bow echo” is a specific radar signature, typically attributed to thunderstorms that carry particularly strong winds. The strong winds are the result of a rear inflow jet, which stems from winds being drawn into a system and subsequently being driven towards the surface by the trailing portion of a thunderhead. The strong, descending winds force thunderstorms forward at a pace greater than areas where the inflow jet is nonexistent. The accelerated portion of a line of thunderstorms thereby leads to the bow shaped radar imagery, or “echo”.
Bow echoes can be of varying size, ultimately determined by the breadth, rather than the strength, of a rear inflow jet. They point to the direction of storm motion. At either end of a bow echo, the speed shear in the lower levels leads to vortices which can be conducive to tornadic development, with a bias towards the southern vorticies.

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