A confluence of storm systems developing in the Gulf of Mexico and off Florida’s east coast was set to drive a consistent pattern of heavy rainfall into the Miami area Wednesday through Thursday, which could lead to flooding, potentially exacerbated by high tides.
There is a moderate risk of widespread excessive rain of three to eight inches, which could lead to flooding from the Florida Keys through Miami and Fort Lauderdale and up to Boynton Beach. Computer forecast models show there could be significant rainfall within the confines of the Keys Wednesday morning, extending north by afternoon, Weather Prediction Center forecasters said.
Some uncertainty in the forecast
Although “wall-to-wall rain” was already falling across South Florida by early afternoon Wednesday, Brandon Orr, a local meteorologist with National Weather Service forecasters in Miami, said there was still some uncertainty about the timing of the heaviest rainfall and the exact location of the highest amounts. It would depend on how quickly the storm system developed off Florida’s southeast coast, but their best indication was that the bulk of the rainfall would be Wednesday afternoon into early Thursday morning.
A busy stretch of Biscayne Boulevard near downtown Miami was already flooded ahead of the heaviest rain Wednesday as vehicles slowed to navigate the area, according to midday footage from WPLG, a local ABC affiliate. And grassy areas along parts of Interstate 95 in Fort Lauderdale already looked like small bodies of water.
Despite those discrepancies, forecasters with the Weather Prediction Center said the models show a solid 90 percent probability of five inches of rainfall or more across the upper Keys into a zone stretching from Homestead up to Miami, giving them confidence until the heavy rain will fall.
High water and saturated soil can make it worse.
Much of this region already has saturated soil from recent rains, especially in Broward and southern Palm Beach Counties, where three to six inches of rain fell on Tuesday. Soil acts like a sponge: if you keep adding water to it, eventually it can’t hold any more.
It all depends on the timing, Weather Bureau forecasters said, but if heavy rain also falls around periods of high water in some coastal communities, the water will have trouble receding. The tides are not relatively as high as they have been when the tides peaked last month, but with the new moon and a strong onshore breeze, they will be moderately high on Wednesday.
When does it end?
This will most likely only last 24 hours. As the storm system moves past the area and up the coast, things should begin to slow down Thursday night. Conditions should gradually improve with drier air filtering in cooler air pushing through the area.
As of Wednesday morning, it was too early to say whether the system will bring significant rain along the East Coast as it moves north in the coming days.
Johnny Diaz contributed with reporting.