Nicole went from subtropical storm to a tropical storm, but is there a difference?
MIAMI - Nicole went from being a subtropical storm to a tropical storm, but are they different or the same thing?
They are different but similar in some ways. They are both low pressure centers that can eventually become hurricanes but one is a completely warm core and the other is a mix of both warm and cold. So let's take a look at them and add one more low pressure system, extratropical.
Extratropical Storms
These are non-tropical lows that are attached to either a cold front, a warm front, or an occluded front. We see them on weather maps crossing the country at all times of the year. They bring precipitation and can move over land or ocean water. They have a cold core and their winds can be strongest far away from the center. Their energy comes from the contrast between cold air to the north and warm air to the south, that's why there is always a front tagging along.
Tropical Storms
We know these very well! They form over warm, ocean water which is the fuel and that water temp needs be at least 80 degrees. Heat energy is released when water vapor evaporates, it condenses and forms rain. The core is warm because of all this heat. High pressure sitting over the center can help the center of circulation breathe or ventilate. If conditions are favorable, a hurricane can form as winds reach at least 74mph. The strongest winds are usually close to the center or core.
Subtropical Storms
These are the hybrid storms. They are a combination of both tropical and non-tropical systems. They can start as an extratropical low over the ocean with the strongest winds away from the center. But as the warm ocean water starts to warm the core, it can transition into a tropical storm. They get their energy from both warm and cold air at the beginning. Over time, the warm water supplies the fuel.
These systems need to be watched and tracked since all three can evolve into a hurricane.
