Nearly 26 inches of rain brought Fort Lauderdale, Florida, to a screeching halt Thursday, swamping cars on highways, shutting down the city’s airport and closing schools.
The sheer magnitude of the tsunami from the skies took nearly everyone by surprise.
“Spotty flooding is expected,” the city posted in an update on its website early Wednesday morning. The National Weather Service expected up to six inches of rain but ultimately at least one location at the airport saw four times that.
If the preliminary report of 25.91 inches measured at a station at the Fort Lauderdale-Hollywood Airport is verified, it would break the state’s 24-hour rain record by 2.63 inches.
Much of Wednesday’s rain at a couple of weather stations – up to 20 inches – fell within six hours, reported weather service meteorologist Pablo Santos. Such an extreme rain amount has only a 1 in 1000 chance of occurring in Fort Lauderdale in any given year, Santos said.
Many locations in the city and surrounding Broward County received more than 11 inches.
More rain than some hurricanes
Florida is prone to storms that dump large sums of rain (that happens when you’re a peninsula surrounded on three sides by water).
Southerners, especially Floridians, are used to heavy rain. The state juts out like a hitchhiker’s thumb into the warm, moisture laden air of the Atlantic Ocean and the Gulf of Mexico, a conveyor belt for storms.
Rain falls by the feet during hurricanes and comes down by the inches during afternoon thunderstorms. The rainfall record during Hurricane Ian last fall was 26.95 inches.
Unfazed Florida drivers often push through sheets of rain so thick you can’t even see the nose of your car and grouse about out-of-towners driving with their flashers on. This storm, however, was anything but typical.
So what happened in Fort Lauderdale on Wednesday and why?
Frankly, it’s complicated. Several factors aligned in just the wrong way. And it left a rainmaker virtually stalled over the city for hours.
While early morning forecasts warned the alignment of weather systems could produce rainfall amounts up to six inches, the storms dumped up to four times that much rain over Broward County.
- Early Wednesday, a slow-moving frontal boundary to the south was lifting very slowly northward.
- Ahead of and alongside the front, winds converged from two different directions, bringing moist air and creating slow moving thunderstorms along the coast and offshore.
- The conflicting weather patterns interacted in a way that can be difficult to anticipate on a local basis.
- Storms continued to build as the warm front crept northward, drenching Broward County with the incredible rainfall totals.
One neighborhood near the airport became an island surrounded by water. A weather service crew on Thursday noted water three feet deep outside a building at a city park.
City officials said Fort Lauderdale’s stormwater system was built to handle 3 inches of rain within 24 hours, but more than a foot fell across broad swaths of the city. At the same time, higher than normal tides were pushing water inland along the coast.
Cities across the country are built for similar so-called 24-hour rainfalls and storms such as the estimated 1,000 year storm in Fort Lauderdale aren’t even contemplated.
Has similar rainfall happened before?
Yes. Even if Wednesday’s rain total is verified as the new state record in Florida, it won’t even move the state into the nation’s top three for 24-hour record rainfalls. Those spots belong to:
- 49.69 inches, April 2018, Waipa Garden, Kauai, Hawaii
- 42 inches, July 1979, Alvin, Texas
- 32.52 inches, July 1997, Dauphin Island Sea Lab, Alabama
But the rain records in Texas and Alabama were set during hurricanes and tropical storms – and Kauai is Hawaii’s rain forest.
Florida’s current record – 23.28 inches – was set on Nov. 11-12, 1980 in Key West.
Situations similar to Wednesday’s setup over South Florida have been blamed for other historic rainfalls.
In Waverly, Tennessee, 17 inches of rain shattered the state’s previous one-day record rainfall by more than 3 inches in August 2021. An upper-level low was steering Tropical Storm Henri northward, while a stationary boundary on the opposite side of that low was streaming moisture in from the Gulf of Mexico, building a lake in the skies overhead. The resulting flood killed 20 people.
Tremendous rain from similar colliding weather patterns has even happened in South Florida. On April 25, 1979, a trough of low pressure over the eastern Gulf and a large high pressure system over the western Atlantic became nearly stationary. Heavy thunderstorms intensified overnight and dumped more than 14 inches of rain between 1 a.m. and 7 a.m.
Weather service experts have said such systems can be among the most difficult to forecast on a hyper-local basis, but new models under development are expected to help them predict such epoch rainfall more precisely.
Could climate change play a role?
Simply put – yes.
Temperatures at the surface in the Gulf of Mexico have been warmer than normal for months. And warmer air holds more water: 7.5% more moisture for every 1.8 degree Fahrenheit increase in temperature.
With temperatures in the Gulf running 3 to 4 degrees above normal recently, that’s at least 15% more rainfall piled up on top of a “normal” storm.
The bathtub-like warmth in the Gulf already has been partially blamed for the all-time record tornadoes in the first three months of 2023, and the typical tornado season is only just getting started.
Some scientists say they’re seeing extreme rainfall events appear with increasing frequency as steering currents collapse and set heavy rain storms adrift over the landscape.
Over 140 years of weather records in the U.S., 45% of the standing 24-hour rain records were set in the last 30 years.
Scientists say the warming climate may help juice up convective storms even more in the future. But they don’t know yet how all the various factors that play into such storms will affect each other.
If Wednesday’s storm proves anything, it’s that if the right things come together, Mother Nature can still throw a mean – and unexpected – punch.
What about Florida’s historic rainfall during Hurricane Easy?
Sometimes it’s hard for a rainfall measurement to get the respect some people feel it deserves.
Many consider the 38.7 inches of rain that fell in Yankeetown, Florida on Sept. 5, 1950 to be the state record. However, NOAA’s state climate extremes committee has stated that even though that rain value to be considered reas [sic]
Value: 23.28 in.
Dates: November 11–12, 1980
Location: Key West
Station ID: 12836
The previously reported extreme of 38.70 inches at Yankeetown on September 5, 1950, is an estimated depth of rainfall calculated as part of a post-storm survey of Hurricane Easy (Cedar Keys Hurricane). Value has historically been considered reasonably accurate (and even an underestimate of actual rain fall), but as an estimate cannot be considered an official observation from a reliable precipitation gauge.
Source: Dinah Voyles Pulver, usatoday.com/story/news/nation/2023/04/13/fort-lauderdale-rain-flooding-explained/11660280002/