Tropical Storm Debby Inches Toward Florida

Tropical storm Debby continues to lash Florida and Alabama with heavy rainfall, coastal flooding, and tornadoes as it sits and spins about 75 miles offshore of Apalachicola, Fla. Dry air has choked off the thunderstorms that had developed close to the storm center, leaving a low-level swirl of clouds and showers along the Florida Panhandle, with rounds of squally rains whipping across central Florida.

Visible satellite image taken on June 25, showing the low level swirl of clouds near the storm's center, just south of the Florida Panhandle. Click on image for a larger version. Credit: NOAA.

At least one fatality was reported as a result of the more than a dozen tornadoes that touched down across the state over the weekend. Land-falling tropical storms and hurricanes often bring the threat of tornadoes, although they tend to be on the weaker end of the scale.

The main threat from Debby continues to be flooding from excessive rainfall, with radar estimates showing that 10 inches or more had already fallen during the past three days in central and northern Florida, with another foot or more yet to come, depending on the storm’s track and strength. The forecast does not call for Debby to move away from Florida and into the Atlantic Ocean until June 29.

Persistent tropical storm force winds from the south and southwest have also piled up water along the west coast of Florida, with moderate storm surges of up to 3-to-5 feet reported from Apalachicola to Tampa. The National Oceanic and Atmospheric Administration (NOAA) posts tidal data in real-time from many Florida locations, including Old Port Tampa, Cedar Key , and Apalachicola. In the coming years, climate change-related sea level rise, along with land elevation changes, are likely to exacerbate storm surge flooding from even weak tropical storms such as Debby.

The National Hurricane Center’s (NHC) 11 a.m. ET advisory stated that Debby had maximum sustained winds of 45 mph, down from 60 mph on Sunday, and the track forecast shows the storm meandering northeast, and then slowly east across northern Florida. The dry air is proving to be a significant hindrance to the storm, preventing intensification, the NHC stated.

“WITH DRY AIR LURKING AND WESTERLY SHEAR ON THE INCREASE OVER THE NEXT COUPLE DAYS . . . SIGNIFICANT RE-INTENSIFICATION OF THE CYCLONE PRIOR TO LANDFALL SEEMS UNLIKELY,” wrote an NHC forecaster in a technical discussion on Monday morning.

Florida rainfall during the past week, showing a swath of 10 inches or more across north central Florida. Click on image for a larger version. Credit: NWS.

Unlike on June 24, when computer models projecting the storm’s path gave weather forecasters wildly conflicting signals – with some taking the storm west toward Texas, and others moving it into Florida – the models have come into somewhat better agreement that Debby will eventually make landfall in the Sunshine State and move to the east, eventually making its way to the Atlantic Ocean.

However, where the center of the storm crosses the coast is not all that important, since the storm is so broad that it is dumping heavy rain well away from its center of circulation.