An area of low pressure is drifting in the northwest Caribbean and could develop tropical conditions while it travels into the Gulf of Mexico and toward the west coast of Florida by the end of the week, according to the National Hurricane Center.
Forecasters place the chance of development around 40 percent in the next five days.
In the Tampa Bay area, flood warnings have been extended for the Alafia River in Lithia and the Little Manatee River at Wimauma as the National Weather Service continues to monitor the system.
And with more rain expected the next few days, even more rivers could be at risk, forecasters said.
Even if it did not develop into a tropical system, an already drenched region can expect even more showers and thunderstorms.
"At best, it will be spreading a lot of rain our way by the end of the week," said Paul Close, a meteorologist for the National Weather Service. "Most of the rain will fall on Friday and Saturday, it’s possible to continue into Sunday."
Close said this weekend will be cloudy with off-and-on rain that will be heavy in some areas.
According to Close, the gulf waters are not warm enough for a low-pressure system to sustain tropical conditions. Chances for development will be higher later in the year when Gulf waters warm over the summer.
But, Close warns, flooding could be a significant problem this week.
"Flooding will be a problem in general, especially urban flooding and low-lying areas," Close said. "We’ve had two or three days last week where we had 2-3 inches of rain within a few hours that flooded roads. That could happen this weekend."
A flood warning remains in effect for the Alafia River until Wednesday night. Flood stage is 13 feet. It had reached 14.2 feet Monday night and was expected to rise to 14.5 feet on Tuesday before subsiding Wednesday afternoon.
The Manatee River reached 11½ feet Monday night, a half-foot above flood stage.
Over the next two days, the Tampa Bay area will see that familiar summertime rain pattern of scattered showers and thunderstorms firing up primarily in the afternoon, forecasters said.
The rain has already caused some minor flooding in the area and caused four sinkholes to form at the Villages retirement community in Central Florida.
As the week grinds on, folks should plan their morning and evening commutes with rain in mind. Rain chances will be at 60 percent throughout the week, and Memorial Day weekend could be a washout, forecasters said.
730 PM Special Tropical Weather Outlook. Medium chance (40%) of development of a broad low pressure system is possible late this week over the central or eastern Gulf of Mexico. Locally heavy rainfall is the main threat across western Cuba & Florida during the next several days. pic.twitter.com/YOxqiGDPhf— NHC Atlantic Ops (@NHC_Atlantic) May 22, 2018