This study utilized WSR-88D and research Doppler
radars, a boundary layer wind profiler, microwave radiometer, mesonetwork,
mobile CLASS soundings, and theory to understand the convection initiation process
associated with a prefrontal bore wave created by the intrusion of a gravity
current-like cold front into a shallow, surface-based stable layer. A line
of severe thunderstorms erupted behind the bore front. A low-level jetlet
accompanying the bore provided an efficient wave trapping mechanism, due to
wind curvature effects on the Scorer parameter profile, as well as the effects
of low-level shear on the mass convergence field.
Computations of the effects of the bore and subsequent gravity current passage
on the ambient atmosphere show that the strong bore-induced lifting was
insufficient to trigger the storms; rather, it was the dual lifting provided by
the bore and the gravity current that made it possible for parcels to reach
their level of free convection. These results suggest that lifting
sufficient to trigger deep convection must be sufficiently deep or have long
duration.