A look at weather extremes and the big-picture climate connections.

Tropical Storm Debby Floods Florida, Ends Drought

Thanks in large part to Tropical Storm Debby, much of central and northern Florida has made a stunning turnaround from extreme drought conditions to severe flooding in a matter of days.

June is now on track to become one of the wettest such months in the state’s history, and numerous locations throughout the state are making a run at their record for the wettest June, if they haven’t surpassed it already.

24-hour precipitation totals between June 25 and June 26 across northern Florida. Click on the image for a larger version. Credit: NOAA/NWS.

By following a slow and erratic path in the northeastern Gulf of Mexico, Tropical Storm Debby has dumped extraordinary amounts of rain on the Sunshine State, with many locations receiving at least 6 inches of rainfall — and the rain is still falling. Wind shear has kept the most active part of the storm on its eastern flank – directly on top of Florida.

For example, as of June 25, Tarpon Springs had already received 21.04 inches of rain during June, eclipsing the record for the wettest June by nearly 3 inches. It has also been the wettest June in Tampa since records began there in 1890, according to the National Weather Service.

On June 25, a persistent band of heavy rain set up across northern Florida, from just south of Tallahassee eastward to the Atlantic Coast. Some areas affected by this band saw 10-to-20 inches of rain in one day — thus it’s not surprising that parts of Highway 10, the main east-west thoroughfare across the Florida Panhandle, were closed due to flooding.

During a 72-hour period ending at 8 am on June 25, two observing locations reported rainfall totals more than 20 inches. Sanborn reported 26 inches of rain, while St. Marks reported 21.09 inches. Wakulla Springs State Park also was inundated with 18.79 inches.

U.S. Drought Monitor from May 15, showing the severe drought conditions across Florida and Georgia (shaded in red). Credit: Drought.gov.

The extraordinary rainfall totals from Tropical Storm Debby, as well as from a different rainfall event about two weeks prior, have all but erased what had been a very serious drought situation in central and northern Florida. The wet season in Florida typically begins sometime in May, aiding in drought recovery, but this year it has seemed more like a deluge season.

A sudden switch from drought to flood is rare but not unheard of. As global warming causes the water cycle to intensify, with wet and dry extremes increasing in frequency and severity, such whiplash events may become more frequent. Already, the atmosphere holds about 4 percent more water vapor now than it did during preindustrial times.

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