 Convective rainbands can form parallel to terrain on its windward side , due to lee waves triggered by hills just upstream of the cloud 's formation . Their spacing is normally 5 kilometres ( 3 @.@ 1 mi ) to 10 kilometres ( 6 @.@ 2 mi ) apart . When bands of precipitation near frontal zones approach steep topography , a low @-@ level barrier jet stream forms parallel to and just prior to the mountain ridge , which slows down the frontal rainband just prior to the mountain barrier . If enough moisture is present , sea breeze and land breeze fronts can form convective rainbands . Sea breeze front thunderstorm lines can become strong enough to mask the location of an approaching cold front by evening . The edge of ocean currents can lead to the development of thunderstorm bands due to heat differential at this interface . Downwind of islands , bands of showers and thunderstorms can develop due to low level wind convergence downwind of the island edges . Offshore California , this has been noted in the wake of cold fronts . 
