“…Gravity waves may propagate ahead of a system and thereby modify the inflow conditions (Fovell, 2002), and short gravity waves close to the system may contribute to triggering of new cells ahead (Fovell et al, 2006), especially where small but significant convective inhibition (CIN) may be modified by the waves (Morcrette et al, 2006;Marsham and Parker, 2006). Furthermore, a great deal of work has focussed on propagation mechanisms involving coupling between gravity waves and convection, as summarised by Cram et al (1992), including wave-CISK (convective initiation of the second kind) theories (Raymond, 1984) and the role of upper tropospheric gravity waves in exciting the rear inflow jet (Schmidt and Cotton, 1990). Pandya and Durran (1996) show that key features of two-dimensional squall lines can be accounted for directly from the gravity-wave response to the mean heating profile, largely that arising from the leading edge convection.…”