The system threatening an October surprise for the area doesn't have a human name yet, though meteorologists are calling it Invest 99L. For now, the system is a loosely linked mess of storms and rain hanging over western Cuba and the Straits of Florida.
The problem is that the water between Miami and Havana is extraordinarily hot right now, and — combined with an upper-level low over the Gulf — might be just enough fuel to help the system spin up into a bonafide tropical storm between now and Saturday night.
National Hurricane Center (NHC) forecasters give the system a 40 percent chance of developing into a named storm by Sunday, but they say regardless of how well it organizes, there's a good chance the storm will wreck your weekend plans in South Florida or the Keys.
"This system is likely to produce locally heavy rainfall over portions of central and western Cuba, the Florida Keys, the Florida Peninsula during the next several days," the NHC says in its 8 a.m. Friday advisory.
Forecasters also have bad news for Puerto Rico, the U.S. Virgin Islands, and the Leeward Islands that are still reeling after Hurricane Maria's terrifying attack last week. Another tropical wave is bubbling up in the northeastern Caribbean and — though it has only a 20 percent chance of developing now — could become better organized as it moves northwest.
That means Puerto Rico and its neighbors are, at the very least, due for some heavy downpours at a time when they need it least.
"This system is expected to bring locally heavy rains over the northern Leeward Islands, including Puerto Rico and the U.S. Virgin Islands," the NHC says.