A tropical disturbance outside of hurricane season? What’s that? It’s actually more common than you might think. On May 1 of 2019 a tropical disturbance formed, moving through the Bahamas. A tropical disturbance is just a cluster of thunderstorms that hold together as a group for a few days, without having a circulation. These are very common in the tropics but we only think of them happening in hurricane season. All they tell you is that water around them is relatively warm and wind shear is fairly light, within a broad region of low pressure.
While the calendar hurricane season in the Atlantic runs from June through November, disturbances can happen at just about any time. In fact, disturbances that became tropical storms have been recorded in every month of the year. NOAA reports that 3% of tropical activity is outside of hurricane season.
Does an early-season tropical disturbance tell you anything about the upcoming hurricane season? No.
In 2018, just for example, there were 3 disturbances in May. In 2017 there were 2 in April. Each of the last 5 years had early-season disturbances but each of the seasons was very different.
Higher resolution satellites show us more things than we have been able to see in the past so expect to hear about more tropical systems outside of hurricane season, as years go by. Larger communication networks and social media now put more things in front of you than ever, but it doesn’t always mean things are changing.
Learn more about the tropics in the WKRG Weather Education web section.