Abstract
Winds and vertical velocities are examined in ten southerly low-level jets and then averaged in coordinate systems centered on the jet. The jet at 0600 CST is strongly supergeostrophic but is reflected in both geostrophic and ageostrophic components of the wind. Air is typically rising downstream from the wind maximum and sinking just upstream from the jet core. This orientation of vertical velocities provides a possible explanation for the high frequency of nocturnal thunderstorms in the midwest.
