Environment

Blame El Niño for South Florida’s soggy winter

El Niño is likely to cause wet weather this winter.
El Niño is likely to cause wet weather this winter.

Has El Niño unleashed its forewarned fury on South Florida or are we just get hammered by fluke winter rain?

The answer is both. When record rain drenched the region this month — one South Dade neighborhood got more than 10 inches in 24 hours — it was against a backdrop of the deepening El Niño over the Pacific. The weather pattern didn’t create the soggy front that has stalled over the region, or the above average temperatures and rain marking the year’s end. It just made them worse.

“You can’t point the finger at El Niño for every little thing,” said Robert Molleda, the National Weather Service’s warning coordination meteorologist for the Miami forecast office. But you can blame it for “setting the stage.”

And until it goes away, likely in late spring or early summer, climate scientists say there’s an 80 percent chance this El Niño will keep us plenty wet.

Coming off a damp November, December is already breaking records dating back nearly a century. Between Dec. 2 and Dec. 8, rainfall in eastern Miami-Dade County totaled 9.02 inches, according to the South Florida Water Management District. Eastern Broward had 5.89 inches. In an average year, the two areas get just 1.91 inches and 2.15 inches during those dates.

That much rain can cause all kinds of problems, and not just at Zoo Miami, which closed this week after zookeepers worried lions might ford water-filled moats. At the water management district, engineers began lowering water in the region a week ago, said Jeff Kivett, director of operations, engineering and construction. But even with water at the lowest level allowed to protect regional water supplies, the system still failed in places.

In Doral, lakes overflowed and filled fairways while cows huddled on higher dry land in flooded pastures. Water submerged roads from Homestead to Coconut Grove. Near Miami International Airport, water managers had to pump water into a rarely used reservoir built after a “no name” storm in 2000 dumped more than a foot of rain in less than 24 hours. Farmers in South Dade plan to meet Thursday to talk about seeking emergency relief from flooding.

When you get a storm of this magnitude, it just physically doesn’t have the capacity to move water out of the system fast enough.

Jeff Kivett, South Florida Water Management District

“When you get a storm of this magnitude, it just physically doesn’t have the capacity to move water out of the system fast enough,” Kivett said.

Water managers, along with climate scientists, have been anticipating the impacts of an El Niño since Pacific water temperatures began rising last year. They expected the El Niño system to form last year, only to have it falter.

In a complex network of basins, water managers try to balance flood protection against the risk of having too little water if rain falls below projections.

“Even in an El Niño you could have average rain, so we really watch both sides of the ledger,” Kivett said.

In November, South Florida felt more like May, forecasters said. A high pressure system over the eastern U.S. helped keep cold fronts from moving south, causing three fronts to stall just south of Lake Okeechobee. At Miami International Airport, temperatures were 3.5 degrees above the 30-year normal, forecasters said. Six minimum-temperature records for the month were either tied or broken. September and November were the second warmest on record since 1986.

The El Niño didn’t cause the fronts to stall, Molleda said, but they did pack the air with the moisture needed to create the wet cloudy days shrouding the region.

Scientists can’t say for sure what single event triggers an El Niño. Typically the weather pattern occurs in the Pacific after normal east-west winds weaken and ocean temperatures rise. In a normal year, winds blow from east to west along the equator in the Pacific, allowing warm water to pile up in the west and remain cold in the east, said University of Miami climate scientist Ben Kirtman.

Without the winds driving the water, the difference in water temperatures can lessen, further weakening winds.

“It’s sort of a range of possible phenomenons that we think we understand,” he said.

With winds disrupted, the subtropical jet stream that runs from the central Pacific over the Gulf of Mexico can strengthen and drift south, bringing more storms over the Florida peninsula.

“It brings the action a little further south,” said Brian McNoldy, a senior research associate at the University of Miami’s Rosenstiel School of Marine & Atmospheric Science.

In addition to rain, El Niños can fuel even more severe weather. During a 1998 El Niño, a chain of tornadoes in Central Florida killed 42 people and caused $24 million in damage.

“No one can predict how many or when this early on, but we do know based on past El Niños.... they set the stage for an increase or possibility of these stronger systems,” Molleda said.

Depending on how you measure it, this year’s El Niño could break the 1997-98 record. Last week, National Oceanic and Atmospheric Administration forecasters said they expect the pattern to peak this winter and weaken in the late spring or summer. Water temperatures in some areas of the Pacific could break records set in the 1950s, said NOAA forecasters, who plan to issue an updated three-month outlook Thursday.

While scientists are still trying to understand what role climate change may play in El Niños, Kirtman said a few tenths of a degree rise in temperature since the 1997-98 El Niño is probably a factor in how this year’s system is shaping up.

Even a relatively smaller El Niño may have bigger impacts because background temperatures have gone up.

Ben Kirtman, University of Miami climate scientist

“There’s no doubt the El Niños will be superimposed on a changing climate. That won’t go away,” he said. “So even a relatively smaller El Niño may have bigger impacts because background temperatures have gone up.”

More extreme conditions — this fall’s heavy rain follows a regional drought that parched parts of southern Miami-Dade County and Florida Bay — could also make managing water in the region tougher, he said.

“You have more extremes and amplitudes of extremes,” Kirtman said, “so I think the systems are going to be challenged even more.”

Jenny Staletovich: 305-376-2109, @jenstaletovich

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