MIAMI - Post-Tropical Cyclone Isaias was churning north through central Alabama early Saturday, but the storm’s most dangerous threat remained squarely aimed at the Florida Panhandle and Big Bend region, where the National Hurricane Center warned localized rainfall totals could reach 15 inches through the weekend.
At 4 a.m. CDT Saturday, the NHC placed the center of Isaias about 25 miles southwest of Montgomery, Alabama, moving north at 14 mph with maximum sustained winds of 35 mph. The system’s minimum central pressure stood at 1002 millibars. Despite its post-tropical classification, NHC forecaster Blake warned that flash flooding, urban flooding, and river flooding remain likely across a wide swath of the Southeast, with the Florida Panhandle and Big Bend facing the most severe exposure.
“Considerable impacts” are expected across much of southern Alabama and the Florida Panhandle into southwestern Georgia, according to the advisory. The NHC projects 4 to 8 inches of rainfall across the Florida Panhandle and Big Bend through the weekend, with isolated pockets capable of receiving up to 15 inches - a threshold that would overwhelm drainage systems and trigger significant river flooding in low-lying coastal communities.
The tornado threat has not passed for Florida. The NHC advisory noted a risk for tornadoes persisting through Saturday afternoon across parts of the eastern Florida Panhandle, extending into Georgia and the Carolinas. Residents in Escambia, Santa Rosa, Okaloosa, Walton, Holmes, and Washington counties were urged to monitor local National Weather Service products through the day.
Along the Gulf Coast, storm surge that battered Florida’s coastline as Isaias made landfall is now receding. The NHC confirmed that all Storm Surge and Tropical Storm Warnings have been discontinued as of the 4 a.m. advisory - the 15th and final public advisory the National Hurricane Center will issue on Isaias. Responsibility for the system transfers to the Weather Prediction Center beginning at 10 a.m. CDT Saturday.
Swells generated by Isaias will continue affecting Gulf coasts of the United States, Mexico, and western Cuba through the weekend. The NHC characterized those swells as likely to produce life-threatening surf and rip current conditions, a warning that applies to Florida’s Gulf-facing beaches from the Panhandle south through the Nature Coast.
The NHC forecast track carries Isaias across Alabama and into the Tennessee Valley later Saturday, with a turn toward the north-northeast or northeast expected Sunday. The system is forecast to dissipate entirely by Sunday, at which point the Weather Prediction Center will issue the final advisories under AWIPS header TCPAT4.
For Florida residents in the Panhandle and Big Bend, the window of greatest flood risk runs through Saturday night and into Sunday morning as the heaviest rainfall bands rotate through. The NHC directed residents to the National Weather Service Storm Total Rainfall Graphic and Flash Flood Risk graphic at hurricanes.gov for updated rainfall projections as the system evolves. Local NWS offices in Tallahassee and Mobile are expected to issue updated flash flood watches and warnings throughout the day as rainfall totals come into focus.