What is a mid-latitude cyclone? It is the large area of low pressue with a warm and cold front associated that is so common to our weather. A hurricane has no fronts. These two can look similar when observed from radar or satellite but they are very different with a few similarities. Eastern North Carolina experiences both of these storms on a regular basis so let’s discuss briefly the similarities and differences of the two.
A hurricane is considered a “warm core” low, thus it derives its energy from the warm ocean water and the heat release of the condensation process. A mid-latitude cyclone is considered a “cold core” low and derives its energy from the contrast of the cold and warm air ahead of and behind the fronts.
Hurricanes usually weaken and get ripped apart with higher elevation (about 40,000 ft or higher), whereas a mid-latitude cyclone intensifies with higher elevations as there is a cold upper level low pressure that exists in those higher elevations.
A hurricane usually contains an eye with sinking air, whereas mid-latitude cyclones have a center of low pressure with rising air. Hurricanes have their strongest winds around the eye of the hurricane where mid-latitude cyclones have their strongest winds aloft, in the jet stream.
There are some similarities, however. Both are areas of surface low pressure and both have winds moving counter-clockwise around their respective centers. Some nor’easters (mid-latitude cyclones) actually possess some hurricane characteristics. One nor’easter in January 1989 actually formed a cloud free eye with winds about 85 mph spinning around the warm inner core.
In addition, some polar low pressure systems may also exhibit characteristics of a hurricane such as the symmetric bands of thunderstorms spiraling inward around a cloud free eye, a warm-core area of low pressure and strong winds near the center of the storm. Sometimes these are called Arctic hurricanes. Even hurricanes can become mid-latitude cyclones once they come on shore and get caught up in an upper level trough.
Two different storm systems but both have high impacts on eastern North Carolina, anywhere from flooding rains, high surf, beach erosion and high winds. Hurricanes have greater winds and can have a more devastating affect, however we see strong mid-latitude cyclones more often, which batters our coastline.