What cold area do tropical disturbances have to survive through to then be rejuvenated by heat and moisture of the warmer water of the mid-atlantic?

Tropical disturbances that form over the warm waters of the mid-Atlantic, have to survive the cold waters on that come down south alongside the west coast of North America. These cold waters come down from Greenland, along the west coast of Canada and then west coast of USA. They bring cold air masses with them that are more dense, heavier, and break down the hurricanes, which is why they are very limited (most of the time) to the southwest of the USA and the Caribbean surrounding area. As they go further north they are becoming weaker and eventually break down.

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.