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This radar image shows a small bow echo moving into extreme northern Franklin County, Indiana.  Bow echoes are usually associated with damaging winds, but they do occasionally produce tornadoes.  These tornadoes are usually weak and short-lived.  Tornadoes that form from bow echoes usually occur just north of the bow's apex, or where it curves out the most.  These circulations typically develop near the ground and grow upward, which makes them different from supercellular circulations which develop aloft and build downward.  Since the lowest radar scan can sometimes be a few thousand feet off the ground, these "spin up" tornadoes can be difficult to detect because radar cannot see them forming so low.