Vertical shears of horizontal winds play an important role in the dynamics of the middle and upper atmosphere. The presence of strong shears can significantly impact and even inhibit the upward propagation of atmospheric gravity waves (e.g., Fritts & Alexander, 2003). Shears in zonal winds are believed to play a central role in producing narrow layers of metal ions associated with Sporadic-E (e.g., Axford, 1963;M. F. Larsen et al., 2005;Whitehead, 1961). In regions of the middle and upper atmosphere where such shears become especially large, the atmosphere can become dynamically unstable, leading to the formation of Kelvin-Helmholtz instabilities (e.g., Li et al., 2005). While climatologies of the winds (e.g., HWM;Drob et al., 2015) reveal only modest wind shears in the lower thermosphere, high vertical-resolution observations (e.g., rocket-trail observations, M. F. Larsen, 2002) frequently reveal shears that are close to this instability threshold, which may have important implications for the neutral dynamics of this region, resulting in modified vertical constituent and heat fluxes as well as dynamo processes impacting the ionosphere.Both horizontal winds and their shears are especially strong in the region of the lower thermosphere where the background vertical temperature gradient turns positive (approximately 100-120 km altitude). These strong winds and shears are evident in global climatologies of the wind (e.g., McLandress et al., 1996;Shepherd et al., 2012), which highlight local amplitude maxima of atmospheric tides at these altitudes. In addition to such climatologies, strong winds and shears are especially notable in individual samples of the winds in this region, where the shears