Structure of an Atmospheric Undular Bore Generated from Colliding Boundaries during CaPE

Abstract

Abstract A case study of a sea-breeze front originating from the east coast of Florida colliding with a gust front moving toward the southeast is presented. Single- and multi-Doppler radar analyses combined with serial balloon ascents suggest that the denser sea-breeze flow undercut the cold pool behind the gust front and may have generated a westward-propagating undular bore. In addition, another undular bore was generated by the collision and propagated eastward through the CaPE network. The latter bore propagated upstream, against the southeasterly flow behind the sea-breeze front and was apparent as a narrow band, 5–6 km wide, of near-zero radial velocities embedded within an overall flow that was positive as seen by the CP-4 Doppler radar. As the eastern bore propagated through the dual-Doppler lobe defined by the NCAR CP-3 and CP-4 radars, a detailed and unique wind synthesis revealed its three-dimensional kinematic structure. Significant along-bore variability was shown in the convergence and verti...