The nation tied its all-time record from 2015 for average high tide flood days in 2018 with five such days, and experts at NOAA predict that 2019 will prove even wetter thanks to climate change.
But curiously, despite all the days water made roads impassable and King Tide flooded parks and coastal roads in South Florida, by NOAA’s count, the region saw no high tide flood days in 2018.
That’s because NOAA uses a national standard that doesn’t reflect how South Florida’s low-lying topography makes it much easier to flood than other regions, said NOAA oceanographer William Sweet, the lead author of the new report.
“It doesn’t mean you didn’t experience water in the street. … It’s just in terms of the severity of the flood we’re tracking. We’re tracking a slightly deeper, more severe impact,” Sweet said. “One threshold doesn’t fit all.”
It also means that NOAA’s 2019 prediction — of one to three high tide flood days for South Florida’s Virginia Key tidal gauge — likely means deeper and more frequent floods are in store. It could start with the year’s first King Tide, the highest tides of the year, from July 29 to Aug. 4.
“When we do reach those thresholds we often see sizable amounts of flooding,” said Gregory Dusek, chief scientist for NOAA’s Center for Operational Oceanographic Products and Services.
The predicted number of high tide flood days at the Virginia Key tidal gauge leaps to 10 to 55 days of flooding by 2050.
Record-breaking floodwaters, one of the prime warning signs of encroaching sea level rise, caused road closures, loss of business to coastal enterprises and damage to homes and buildings across the U.S. in 2018. Experts say weather conditions and the warming planet will bring more of them next year.
“The ocean is now at the brim, clogging storm water systems and routinely flooding U.S. coastal communities with saltwater, often with no storm in sight,” Sweet said. “This is high-tide flooding. This is sea level rise.”
While five high tide days a year is enough to break records now, NOAA predicts that by 2030, the national median for high tide days could jump to between seven and 15 days a year. By 2050, it could be between 25 and 75 days a year.
And that’s the median for the whole nation. Low-lying South Florida is likely to see a lot more flood days.
NOAA scientists predict the Southeast could see a 190% increase in flood days next year compared with 2000, the highest of any region in the country.
NOAA has 98 tidal gauges, some of which have been functioning since the early 1900s. One gauge in Baltimore started collecting information in 1902. Back then, Dusek said, it recorded 12 high tide flood days in the first 35 years it operated. Last year, Baltimore had 12 high tide flood days.
“I think this is a good example of how dramatically high tide flooding is changing due to sea level rise,” he said.