The strong current of the Gulf Stream has been a subject of study from the early days of European settlement in North American. It was then and remains today a major influence on navigation. Benjamin Franklin was the first to map this current, but at that time there was little known of its contribution to weather. Apart from local impacts climate, warm waters of the Gulf Stream drive thunderstorms, hurricanes and help spawn dangerous nor’easters in winter months.
Because water loses heat at a slow rate than air, it responds less to day and night temperature cycles. This allows thunderstorm environments to be sustained for longer periods over the Gulf Stream. Rising warm air provides energy for storms and draws surrounding air in to reinforce the process. It’s for this reason that lightning over southeastern states is less pronounced than over the ocean as illustrated by the maps of lightning frequency below. This maximum persists year-round.
For hurricanes, the Gulf Stream is like a paved road. Steer off it, and chances of reaching your destination drop dramatically. Hurricanes often take paths that loosely follow the curvature of Gulf Stream due to the steering force of Bermuda High. This semi-permanent high pressure system is the same steering force responsible for the Gulf Stream itself, so this is no coincidence. When hurricanes travel this “road”, it allows them to reach much higher latitudes than they could reach otherwise.
Nor’easters are a great example of how temperature differences invigorate storm systems. This relates back to waters ability to retain heat. When an outbreak of cold spreads over the eastern U.S., it interacts with air warmed by the Gulf of Mexico and Gulf Stream. As these air masses collide, conditions become increasingly favorable for low pressure to strengthen rapid off the U.S. coast. When storms develop in these conditions and track along the coast, they batter New England states with high winds and heavy snow.