A brief tornado touched down in Osborne County late this Thursday afternoon. Between 4:30 and 5:30 p.m. CDT, several small thunderstorms formed from southwest to northeast across Osborne County. At 5:30 p.m., the southernmost storm produced a weak, brief tornado that touched down in open country, near the town of Natoma. The track was short and no damage occurred. Based on detailed radar analysis and a photograph obtained from Facebook, this appeared to be a non-supercell tornado. There was no pre-existing mesocyclone associated with the storm. Deep layer shear and winds in the low-levels were too weak to support mid-level mesocyclone formation. A regional radar mosaic showed a very lengthy fine line, which extended south-southwest to north-northeast across multiple Plains states, including central Kansas. This storm, along with its neighbors, initiated along this boundary. This further suggests the tornado was non-supercellular given the presence of localized shear and the possible presence of misocyclones along the boundary.
A wavy frontal boundary extended across the Ohio and mid-Mississippi River valleys to a weak low pressure center over Nebraska. The front then turned southward over the western third of Kansas. The fine line appeared to be a separate feature within the warm sector, not associated with the front. In upper levels, the main band of westerlies was zonal over southern Canada. Small substropical highs were just off the coast of California and over the Tennessee Valley. A trough was exiting the Rockies and extended from western South Dakota to western Texas. Prior to thunderstorm development, temperatures were in the lower to middle 80s, with dewpoints in the 60s. Mid-level lapse rates were poor, resulting in MLCAPE around 1500 J/kg. 0-6 km shear was weak, estimated around 25 knots.