Disturbances
All hurricanes start off as some type of tropical disturbance. These disturbance travel along the ITCZ in an East-to-West orientation. There are four main ‘seeds’ that can spark tropical cyclone development:
- Easterly Wave - an area of low pressure that moves westward in the tropical easterlies. The majority of tropical cyclones form from these types of disturbances.
- Old frontal boundary - typically happens late in the season, when energy from an old front will generate thunderstorms over the Gulf of Mexico or Caribbean Sea.
- TUTT - short for tropical upper tropospheric trough, refers to a low pressure in the upper atmosphere that can sometimes generate a tropical cyclone.
- WADL - short for West Africa disturbance line, a line of thunderstorms that moved off the African coast and over the waters of the Atlantic. These lines move faster than Easterly Waves.
Once the disturbance becomes more organized, if certain conditions are in place, it can strengthen into the beginnings of a tropical cyclone.