‘Life-threatening’ flooding in South Florida as severe rains continue to fall

MIAMI – “Life-threatening” flooding was ongoing into Wednesday evening in parts of South Florida, as the National Weather Service warned additional rounds of heavy rain were still to come. Cars waded through deep floodwaters in rush hour traffic on major roadways Wednesday night in Miami, as downpours fell even harder after two days of nearly nonstop rain.

A dire flash flood emergency had been issued for areas between Fort Lauderdale and Miami. Six flash flood warnings are in effect across different parts of South Florida into Wednesday evening, according to Miami’s National Weather Service office, which warned of another 5 to 7 inches of rain an hour that “will make flooding even worse.” The warnings were coupled with a severe thunderstorm warning.

Double-digit rain totals were being realized across a populous stretch of South Florida amid a dayslong torrential rainstorm that will bring downpours through Friday. Some weather stations near Hollywood showed nearly a foot of rain had fallen Wednesday alone. Storm total rainfall may exceed 18 inches in spots.

Stormwater pumps rumbled to life to help push the rainwater out to sea, but they couldn’t drain fast enough to avoid flooding streets and airport tarmacs. Pools of water left low-lying parts of downtown Miami and Brickell impassable. And though the sun wouldn’t set for another three hours, drivers flicked on their headlights and hazards as they warily navigated the flooded streets.

Flood watches were scheduled to cover South Florida, including Miami, Fort Lauderdale, Palm Beach, Fort Myers and Naples, and were extended through Thursday evening.

Rare flash flood emergency issued

A dire flash flood emergency was issued for Dania Beach and Hollywood during the late afternoon hours where 6 to 10 inches of rain had already fallen. Another 3 to 7 inches was anticipated as a band of slow-moving torrential downpours rode west to east along Alligator Alley, or Interstate 75. It was set to expire at 5 p.m. Eastern.

A personal weather station in Hollywood Beach, had tallied 11.59 inches of rain in five hours’ time, with several others logging 11.11 inches.

Through 5:40 p.m., 8.61 inches had fallen at Fort Lauderdale-Hollywood International Airport. That’s the third-wettest day on record at the airport, and it’s the all-time June record. If the airport makes it to 10.22 inches, then Wednesday’s rainfall may claim the second-place spot.

Fort Lauderdale also had its sixth-wettest hour on record between 1 and 2 p.m. Wednesday, when 2.41 inches fell.

Another weather station in Hollywood was up to 11.6 inches for the calendar day, 11.19 of which came down in just six hours. Statistically, that’s an event that should happen on average once every 100 to 200 years.

It’s been just over a year since catastrophic and unprecedented flooding dumped 22.5 inches of rain on the airport on April 12, 2023, and forced its closure.

Increased rainfall rates and more extreme flooding events are strongly linked to human-induced climate change. A warmer world is a wetter world by virtue of the fact that warm air can hold, and transport, more moisture. For every degree the air temperature warms, the air can hold more moisture.

Even though hourly record-keeping dates back to 1973 at Fort Lauderdale International, seven of the wettest hours on record have occurred in the past 10 years, and all have occurred since 2003.

Excessive rain across South Florida

At Sarasota Bradenton International Airport, 3.93 inches fell in a single hour between 7 and 8 p.m. Tuesday, the highest one-hour rain total observed there since hourly observations began in 1972. Some locations saw 8 inches in three hours’ time, an event that on average has just a 0.1 percent chance of happening in any given year.

Downtown Sarasota was virtually impassible for a time during the height of the rainfall, which left streets and intersections submerged as water lapped at area businesses. Some 9.15 inches of rain had been reported at the IMG Academy in nearby Bradenton to start the day.

The same storm system could even acquire some marginal tropical characteristics and is being monitored by the National Hurricane Center. It’s unlikely to develop but is a sign that the oceans are heating up, and it won’t be long before the atmosphere becomes conducive to the formation of tropical storms and hurricanes. In the unlikely event the system does mature, which the Hurricane Center estimates has only a 20 percent likelihood, it would be given the name Alberto.

Rainfall totals as of Wednesday evening

The heaviest rain was concentrated in a west to east zone along Alligator Alley, or Interstate 75. Some rural locations had exceeded 15 inches by 5:30 p.m. Eastern time on Wednesday. Here’s a roundup of 72 hour totals; note that, in the greater Miami-Ft. Lauderdale area, most fell just on Wednesday:

17.41 inches in Hollywood

15.58 inches in Sunny Isles Beach

15.47 inches in North Miami

15.37 inches along Highway 41 in the Everglades

15.0 inches in the Big Cypress National Preserve

14.94 inches along Alligator Alley in rural Collier County

14.07 inches in Miami Shores

13.8 inches in Everglades City

13.5 inches in Dania Beach

10.08 inches at the Desoto Nocatee boat ramp

8.49 inches in Fort Myers

8.29 inches in Lehigh Acres

8.27 inches at the Sarasota Bradenton International Airport

In addition, multiple tornado warnings were issued Wednesday morning as a few thunderstorms acquired rotation, probably because of spin in the vicinity of a stalled front over the area. One warning was for a “confirmed tornado” that was approaching Alligator Alley, the main west-east highway between Naples and Fort Lauderdale that bisects the Everglades. Radar confirmed debris lofted by the tornado. Another tornado warning was issued for a second storm shortly thereafter; that storm passed east of the Miccosukee Service Plaza.

A third warning, which was posted for 10:32 a.m., covered a storm in Martin County just south of Port St. Lucie that was also capable of producing a tornado. The National Weather Service was planning to investigate a possible tornado touchdown with that cell in Hobe Sound. A few additional tornado warnings may be issued before the event winds down Friday.

What’s next

The showers and storms will continue into late Friday, primarily south of a line from Tampa to the Space Coast. By Saturday, storms will become more scattered – typical of summer afternoons in the Sunshine State, though the remnant front may act as a focal mechanism for greater storm coverage.

That’s around the time the low-pressure system will pull northeast into the Northwest Atlantic, and the downpours over South Florida will relent. The surface low may acquire subtropical characteristics as it moves over the warm waters of the Gulf Stream.