US: Post-Tropical Cyclone Helene tracking north-northwestward over central Kentucky evening of Sept. 27 /update 8

Post-Tropical Cyclone Helene is tracking north-northwestward over central Kentucky the evening of Sept. 27, having made landfall as a Category 4 hurricane near Perry in Florida's Big Bend region around 11:10 EDT Sept. 26. As of 16:00 CDT, the system's center of circulation was approximately 80 km (50 miles) south-southeast of Louisville, Kentucky.

Forecast models indicate that the storm will weaken as it tracks west-northwestward across central Kentucky through early Sept. 28 before turning to track southwestward over western Kentucky through early Sept. 29. Helene will likely turn to track southeastward and dissipate over western Kentucky the afternoon of Sept. 29. Some uncertainty remains in the track and intensity forecast, and significant changes could occur over the coming hours and days.

As of the evening of Sept. 27, authorities have rescinded all coastal watches and warnings. The National Weather Services (NWS) has issued multiple tornado warnings, flash flood warnings, and flood warnings, as well as watches and advisories, across the southeastern US and the Tennessee Valley. As the storm system evolves, authorities will likely update and possibly extend the coverage of the weather advisories over the coming hours and days.

The storm is forecast to generate additional rainfall amounts of 2.5-5 cm (1-2 inches), leading to widespread rainfall totals of 15-30 cm (6-12 inches) with isolated higher totals around 50 cm (20 inches) over parts of the central and southern Appalachian mountains. This rainfall will likely result in catastrophic and potentially life-threatening flash and urban flooding and record-level riverine flooding. Numerous significant landslides are likely in the steep terrain across the southern Appalachians. 2.5-7.5 cm (1-3 inches) of rainfall is forecast over portions of the Ohio Valley through the evening of Sept. 29. Tornadoes are possible over southern Virginia and northeast North Carolina through the afternoon and evening of Sept. 27. Swells generated by Helene will continue to affect the coasts of Georgia and the Carolinas over the coming days. These swells are likely to cause life-threatening surf and rip current conditions.

Flooding, damage, and downed power lines have been reported across parts of the Southeast and Ohio Valley as of the evening of Sept. 27; damage assessments are ongoing and it will likely take some time before the full impact of the storm is confirmed. Authorities have reported at least 43 storm-related fatalities across the Southeast, including 17 people in South Carolina and 15 people in Georgia. Moreover, 15 people were injured and 14 buildings were damaged after a tornado passed through Rocky Mount, North Carolina, the afternoon of Sept. 27. Millions of people across the Southeast and Ohio Valley regions are without power as of the evening of Sept. 27, with the worst affected states being South Carolina, Georgia, North Carolina, and Florida.

Florida Gov. Ron DeSantis declared a state of emergency across 41 of the state's 67 counties Sept. 23 before expanding it to 61 counties Sept. 24. President Joe Biden approved a federal emergency declaration for Georgia, Florida, Alabama, North Carolina, and South Carolina. States of emergency have also been declared in Georgia, South Carolina, North Carolina, and Virginia. Mandatory and voluntary evacuation orders are in place across dozens of counties in Florida; for the latest information concerning evacuations, click HERE. Mandatory evacuations are also in place in parts of Asheville in western North Carolina following flooding and in downtown Newport, Tennessee following a catastrophic failure of the Waterville Dam. Water in the Lake Lure Dam in Rutherford County, North Carolina is overflowing; evacuations are in place from the Dam to Island Creek Road. More than 1,600 people across Leon County, Florida have taken shelter. Authorities have warned Tampa residents that it is too late to evacuate; residents should shelter in place. A curfew is also in effect from sunrise to sunset in Taylor County. Voluntary evacuation orders are also in place for Haywood County in North Carolina. Several schools and universities are closed across parts of the Southeast.

Thousands of flights have been canceled and delayed across the southeastern US since Sept. 25, with Tampa, Fort Myers, Atlanta, and Charlotte among the worst affected locations. Tampa International (TPA), St. Pete-Clearwater International (PIE), Tallahassee International (TLH), Peter O. Knight (TPF), Tampa Executive (VDF), and Plant City (PCM) airports have reopened Sept. 27 but additional flight disruptions are likely. Other airports affected by cancelations and delays include Southwest Florida International (RSW), Sarasota-Bradenton International (SRQ), Hartsfield–Jackson Atlanta International (ATL), Charlotte Douglas International (CLT), Jacksonville International (JAX), Miami International (MIA), Fort Lauderdale–Hollywood International (FLL), and Orlando International (MCO) airports.

Sustained heavy rainfall could trigger flooding in low-lying areas and those with easily overwhelmed drainage systems. If weather conditions prove hazardous, localized evacuations, flash flooding, and landslides are possible.

Inclement weather could trigger localized business, transport, and utility disruptions, rendering some bridges or roadways impassable. Flight disruptions at regional airports and temporary port closures are also possible. Stagnant pools of water during and after flooding increase insect- and waterborne diseases, such as dengue fever, cholera, and malaria. Exposure to raw sewage and other hazardous materials mixed with floodwaters poses a serious health threat.