A stationary frontal boundary has set up across the Gulf Coast and into northern Florida, and will persist across the region through at least this coming weekend. With this front, winds often converge, and that may create some spin in the atmosphere. By this weekend, some of the model guidance, especially the European model, is hinting that a weak tropical cyclone — tropical depression or low-end tropical storm — may develop either over the northeastern Gulf of Mexico or the southeastern U.S. coast.
In the past, the National Hurricane Center has even declared the formation of tropical cyclones over land, so this may be the case. Most recently, Tropical Storm Julia formed over the Florida Peninsula during the September of 2016. This was a weak storm, and based on history, these storms that form over or close to land tend to be hefty rain-producers.
Even if a tropical cyclone were to form, it would be very weak and the main impact would be heavy rain and localized flooding. Winds and storm surge will not be an issue, unlike with a strong tropical storm or hurricane. For the remainder of this week, most of the rain activity will be focused across Florida thanks to the stalled-out boundary. Rounds of rain and thunderstorms will move from west to east across the state, some of which will contain localized tropical downpours, especially across the northern portion of the state. Some model guidance indicates the potential that some towns could receive 6 to 12 inches of rainfall into next week on top of the already-saturated soil.
During the weekend shower and thunderstorm activity will arise across more of the Southeast. The most widespread of activity and the greatest risk for rain will be confined to Florida and the coast, but inland areas definitely have the chance for rain as well.
Now by the end of the weekend and into early-next week, a broad area of low pressure may form over the Southeast, specifically near the Florida-Georgia border. The ensemble members of the European model indicate about a 50-50 chance for tropical depression development and a 20-30% chance that this potential cyclone surges into a tropical storm once it moves off the Southeast coast and travels out to sea. If a tropical depression or storm were to form, the highest chance of it impacting the Southeast would be at the start of next week. It will then move offshore during the midweek. Heavy rain, localized flooding, and rip currents at the coast will be the main threats. It likely won’t even feel like a tropical system at all apart from the tropical downpours that will occur.