As Florida’s Gulf Coast braces for the arrival of Hurricane Helene on Thursday evening, forecasters are warning that heavy rain and powerful winds could trigger flooding hundreds of miles inland.
With winds reaching up to 275 miles from its center, Helene is an enormous storm capable of causing severe inland flooding well after it makes landfall, according to the National Oceanic and Atmospheric Administration.
Due to its size, the southeastern U.S. will experience heavy rainfall even before the storm hits.
By Friday, areas in the southern Appalachian region could see up to 18 inches of rain.
Tallahassee, metro Atlanta, and western North Carolina are at significant risk of major urban flooding.
“Intense rainfall, particularly across the mountainous regions of the southern Appalachians, is expected to overwhelm communities with flash floods, landslides, and widespread river and stream flooding,” the NOAA warned in an unusual news release highlighting the threat of inland flooding.
Flooding has been the leading cause of deaths related to hurricanes and tropical cyclones in the U.S. over the past decade.
Destructive winds and flooding will reach far beyond Florida’s coastline.
Although the greatest threat of inland flooding is anticipated in the Appalachian region, the National Weather Service reports that a moderate risk of flooding stretches northward into southern Indiana, Ohio, and extends across the Washington, D.C. metro area.
“Hurricane Helene could trigger a severe flooding disaster in parts of the southeastern U.S., particularly in northern Georgia, upstate South Carolina, and western North Carolina,” warned AccuWeather’s Chief Meteorologist Jonathan Porter.
Flooding will result from a combination of pre-landfall rain and the heavy downpours expected as Helene moves inland.
AccuWeather reported that the region from northern Georgia to upstate South Carolina, western North Carolina, eastern Tennessee, southwestern Virginia, and southern West Virginia has already experienced flash flooding from 2 to 8 inches of rainfall earlier this week, unrelated to Helene.
Virginia Governor Glenn Youngkin has declared a state of emergency in anticipation of Hurricane Helene’s impact, highlighting that the western regions of the state may experience substantial rainfall and flooding on Friday and Saturday.
On a positive note, the heavy rains reaching parts of Virginia, West Virginia, and Kentucky could help alleviate the ongoing drought conditions in those areas.
Why so much rainfall inland?
In addition to its massive size, another element could enhance the inland rainfall from Hurricane Helene: the Fujiwhara effect, which involves the interaction of two storms rotating around one another.
Hurricane Helene may intertwine with another storm system in the south-central U.S., characterized by a trough of low pressure.
This could result in an overwhelming amount of rainfall in states located far from the storm’s center.
Forecasters indicate that the heavy, potentially flood-inducing rain could affect the Mid-South and Ohio Valley in the coming days.
The effect resembles a dance between two storm systems that rotate in the same direction, orbiting around a central point between them, which occurs when they are approximately 900 miles apart.
How to stay safe from extreme flooding
Officials advise that individuals even hundreds of miles from landfall should take safety precautions:
- Evacuate if local emergency management officials issue an evacuation order.
- Know if you reside in a flood-prone area.
- Develop a plan to safeguard your family and belongings.
- Assemble an emergency kit with essentials like water, nonperishable food, medications, and more. Here’s a list of items to include.
- Avoid flooded roads and do not attempt to drive through standing water.
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