Tropical activity typically remains fairly quiet in July before a noticeable uptick in August heading toward the statistical peak of the season on Sept. 10. Roughly two-thirds of all tropical systems in the Atlantic basin form in August or September.
Thankfully, no tropical development is expected anywhere in the Atlantic over the next five days.
Last week, we discussed the factors necessary for tropical development – warm sea surface temperatures, moist air, low wind shear and a tropical wave or disturbance.
In the very early stages of tropical development, an area of low pressure develops at the surface with a well defined, low-level center of circulation. Clouds, showers and thunderstorms swirl counterclockwise around the center.
A tropical cyclone with maximum sustained winds of less than 39 MPH is considered a tropical depression. Tropical depressions are assigned numbers in order of their development.
More and more warm and moist air then converges, rises and cools near the center of the system. Latent heat is released as water vapor condenses into liquid cloud droplets. The added heat released into the system creates more instability and rising motion in the atmosphere.
The pressure at the center of the system will drop as the process continues – surrounding warm and moist air near the surface rushes in toward the center, then rises and cools. More water vapor condenses into liquid water cloud droplets and more latent heat is released. The process allows the cyclone to strengthen. Once maximum sustained winds reach 39 MPH or greater, the cyclone is classified as a tropical or subtropical storm and given a name.
If favorable conditions for development persist, a tropical storm can intensify into a hurricane with maximum sustained winds of 74 MPH or greater. On average, the first hurricane of the season forms around Aug. 10. In a typical season, roughly six hurricanes will develop.
A hurricane is considered “major” once it reaches Category 3 strength or higher with maximum sustained winds of more than 110 MPH. These are the most powerful of tropical cyclones and can cause catastrophic damage. Only two or three hurricanes will reach Category 3 or higher strength in a typical season.
Tracking the Tropics is keeping you prepared and informed throughout the hurricane season. Watch live every Wednesday at 2 p.m. ET for an update.