Extratropical cyclones are relatively well understood. They often follow the Norwegian Cyclone model, which was developed in the 1910's and 1920's. Because of their spatial extent, extratropical cyclones are often less intense than their tropical counterparts. Since they are so much larger and live longer over land, it is easy to get data about an extratropical cyclone.
Tropical cyclones, on the other hand, have faster winds and affect people in a more dramatic fashion. If an extratropical cyclone is announced in winter, a grocery store may run out of bread. If a tropical cyclone is announced, there may not be a clerk available to restock the shelves. Tropical cyclones often don't live very long over land and are smaller, so it is hard to get data about them. Because they are smaller and the wind speed change over distance is so much greater in extratropical cyclones than tropical cyclones, errors in the forecast tend to have more of a dramatic effect on tropical cyclones.
To summarize:
- Extratropical cyclones are often less intense.
- We have an abundance of data on extratropical cyclones.
- The theory behind the development of extratropical cyclones is longstanding and generally well established.
- Tropical cyclones are much more dramatic and concentrated.
- Forecast errors impact tropical cyclones more severely than extratropical cyclones (i.e. less predictable).
