Fort Lauderdale flooding, what happened
The historical flooding in Broward County that shut down the airport, closed schools, stranded motorists and left even veteran meteorologists agog was caused when storms built upon themselves, something called "training."
In a 24-hour period, an unofficial 25.91 inches of rain collapsed onto Fort Lauderdale. The storm even spun up two short-lived tornadoes that sheered treetops and mangled metal siding in a Dania Beach mobile-home community.
“When you are looking at a rain gauge that says 18 to 20 inches, honestly, our first thought was, 'That can’t be right,' ” said George Rizzuto, a National Weather Service meteorologist in Miami. “Nobody was forecasting 20 inches because it’s such a very small possibility that it could happen.”
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What happened? How did they get so much rain?
∎ The atmosphere was primed by a counterclockwise swirl of low pressure in the Gulf of Mexico and the remnants of a front biding its time in the Florida Straits.
∎ The tail of the deepening low-pressure system, which at one point some forecasters thought might transition into a tropical cyclone, grabbed onto the stalled front, dragging it slowly north with a gooey mass of Caribbean moisture heavy with torrential rains.
∎ Energy from the low-pressure system and tropical juice from the front came together over Fort Lauderdale at the hottest time of the day, when the clash of rain-cooled air and Earth-warmed air is the most combustible, said George Rizzuto, a National Weather Service meteorologist in Miami.
∎ The steep difference in temperatures between the rain-cooled air and ambient air caused showers to back build or “train.” Training storms happen when a rush of rain-cooled air that falls from a storm creates an outflow that pushes ahead to form another storm in nearly the same area. Training can continue for hours in the same general vicinity, guaranteeing a relentless rain.
Was it a record rainfall in Broward County?
If the 25.91-inch measurement is verified, it would break the state record of 23.28 inches that fell in Key West on Nov. 11, 1980.
A State Climate Extremes Committee that includes the National Oceanic and Atmospheric Administration and the National Centers for Environmental Information will be convened to review the rainfall measurement, said Florida Climatologist David Zierden.
Fort Lauderdale airport flooding
There were a total of 1,114 flights canceled out of Fort Lauderdale-Hollywood International Airport since Wednesday (207 Wednesday, 659 Thursday, and 248 Friday), according to FlightAware.com. The airport had a total of 286 delays since Wednesday (102 Wednesday, 57 Thursday, and 127 Friday).
Albert Slap, President, RiskFootprint, a Boca Raton-based hazard assessment technology and resilience advisory services company, said the airport is vulnerable to flooding for multiple reasons that will get worse with climate change.
"The flooding of the airport is due to low elevation, how the land drains naturally, lack of permeable surfaces, and, ultimately, the inadequacy of the storm water system to handle such a large rainfall event," Slap said.
What are officials doing?
The South Florida Water Management District has installed additional pumps to drain water from flooded lands.
District Chief Engineer John Mitnik said the canals that drain the water are tidally influenced, meaning inland runoff is competing with saltwater influxes to pool in areas near the coast where water can't easily go out to sea. In some western areas, water is being pumped into water conservation area 3A to keep it from going east.
"There is persistent flooding to the west," Mitnik said. "We get into a balancing act of needing to relieve areas to the west without exacerbating the flooding to the east."
Mitnik said the system was designed for an inch of water a day, so it may take a few days to deal with the flooding from double digit rainfall.
"We had a forecast for a significant amount of rain, but this is an extreme amount of rain," Mitnik said. "It parked itself and did not stop all day long."
Fort Lauderdale flooding photos
When is Florida's rainy season?
The rainy season in South Florida begins May 15 and lasts through Oct. 15. South Florida receives about 36 inches of rain, or 70 percent of its annual rainfall amount, during the wet season.
Forecast for weekend
Rains should taper off for a drier Friday and Saturday. By Sunday, another cool front is expected to sweep through South Florida dragging showers with it. Temperatures won't plummet, but they should return to a seasonal normal with highs in the low- to mid-80s.
Kimberly Miller is a veteran journalist for The Palm Beach Post, part of the USA Today Network of Florida. She covers real estate and how growth affects South Florida's environment. Subscribe to The Dirt for a weekly real estate roundup. If you have news tips, please send them to kmiller@pbpost.com. Help support our local journalism, subscribe today.
This article originally appeared on Palm Beach Post: Why did Fort Lauderdale flood so badly and what is happening today
