Monday, August 23. We were crossing the Sir Francis Drake Channel heading for Tortola. A heavy downpour overtook us and we circled a mile off shore waiting for land to reappear. As the stormed moved West and started to clear, we were again subjected to a thunderstorm advancing towards us from the same storm which had just passed over us.The 1000 foot island triggered the convection necessary to spawn a tropical storm. The storm turned from a squall into a thunderstorm in seconds. The clouds rocketed thousands of feet upwards before our eyes.The next morning this storm had become a hurricane - Dennis.It was amazing to see. All meterological eyes at that time we focussed on the Cape Verde islands. This storm was in our back yard. Had the convection begun fifty to hundred or so miles east of us we would not have had more than a couple of hours warning. Awesome thought!