Florence's Catastrophic Flood Threat Continues From Carolinas to Western Virginia and West Virginia

weather.com meteorologists
Published: September 16, 2018

Florence has weakened to a tropical depression but its siege of heavy rain continues, triggering flash flooding and river flooding from the Carolinas into western Virginia and eastern West Virginia. Portions of the Northeast will also see locally heavy rain from Florence's remnants.

(MORE: Florence's Northeast Impact)

Radar imagery Sunday morning showed bands of rain spreading from northern South Carolina and eastern North Carolina to the southern Appalachians.

Current Radar, Watches and Warnings

A flash flood emergency is in effect for Sampson County, North Carolina, until 9:45 a.m. EDT. Flash flood warnings are in effect for other parts of southeastern North Carolina. Numerous water rescues have reported Sunday morning in these areas.

Flash flood watches have been posted by the National Weather Service in much of South Carolina, North Carolina, southwestern Virginia and far southern West Virginia.

Flood Alerts

Two spots have preliminarily topped North Carolina's tropical cyclone rainfall record: Swansboro with 30.59 inches of rain and a site in Onslow County with 25.87 inches so far. The previous record was 24.06 inches from Hurricane Floyd in 1999.

(MORE: Florence Sets Preliminary North Carolina State Rain Record)

The greatest risk of additional flooding Sunday into early Monday is from northern South Carolina to North Carolina, southwest Virginia and eastern West Virginia.

Here's what to expect for additional rainfall totals, according to the National Hurricane Center:

- 4 to 6 inches (locally 8 inches) from southern North Carolina into northern South Carolina. Storm totals including what has already fallen will be 30 to 40 inches in southeastern North Carolina.
- 5 to 10 inches from central and western North Carolina to far southwest Virginia. Storm totals including what has already fallen are expected to be 15 to 20 inches in western North Carolina.
- 2 to 4 inches (locally 6 inches) in west-central Virginia.

It's important to note that you do not need rain nearly as heavy as what has fallen near the coast of the Carolinas to trigger major flash flooding and landslides in the Appalachians, due to the runoff enhancement of terrain.

The relentless rain that has caused catastrophic flooding in coastal North Carolina will finally let up by Monday but scattered showers and thunderstorms may continue in spots.

Florence Rainfall Outlook

With such extreme amounts of rain, major to record river flooding will continue for days in the Carolinas after the heaviest rain has departed.

Rivers are already high in some spots in eastern North Carolina as seen in the red and purple dots signifying moderate to major flood stage.

Current River Levels

Here are some notable locations where significant river flooding may occur, but keep in mind, forecast changes are possible.

Neuse River at Kinston, North Carolina: Major flooding (21 feet) is ongoing, and it may rise to near 25 feet during the week ahead. Homes and businesses begin flooding when the river reaches 21 feet. This would be just over two feet below the Floyd 1999 crest, and more than 3 feet below the Matthew 2016 crest.

N.E. Cape Fear River at Burgaw, North Carolina: Major flooding (16 feet) is forecast to begin Sunday, and record flooding could by Monday or Tuesday. The current flood of record is a crest of 22.5 feet from Hurricane Floyd in 1999. The National Weather Service noted that homes are flooded when the river reaches 16 feet, and many more take on water as it rises toward the record height.

N.E. Cape Fear River at Chinquapin, North Carolina: This location set a new record flood level Sunday morning, topping the previous record of 23.5 feet from Hurricane Floyd in 1999. "Devastating flooding" occurs across the county once the river reaches 23 feet, according to the National Weather Service. The river may rise a few more feet into early week.

Lumber River at Lumberton, North Carolina: Major flooding (19 feet) is expected on Sunday, and the river level could approach the record set in Hurricane Matthew (2016) of 24.39 feet. Flooding of homes can begin once the river reaches 17 feet. If it rises to 24 feet, Interstate 95 may experience flooding between exits 17 and 19.

Little River at Manchester, North Carolina: Major flooding (27 feet) is expected Sunday. The river could rise above Hurricane Matthew's record flood level of 32.19 feet early this week.

Cape Fear River at Fayetteville, North Carolina: Major flooding (58 feet) is forecast by Monday or Tuesday. It could rise to its fifth-highest level on record if it tops Matthew's flood of 58.94 feet.

Waccamaw River near Conway, South Carolina: Major flooding (14 feet) may by Tuesday, and record flooding is possible by the latter part of this week. The previous flood of record is 17.87 feet from Hurricane Matthew in 2016. Water begins to surround homes when the river reaches 13 feet. Records here date to at least 1894.

Major flooding is also forecast on the Little Pee Dee River at Galivants Ferry, South Carolina, the Neuse River near Goldsboro, North Carolina, the Yadkin River at Elkin, North Carolina, and the Dan River in southwestern Virginia.

Recent Major Inland Flood Events

The most notable recent inland flood from a tropical storm or hurricane was Hurricane Matthew, which produced a swath of 10 to 19 inches of rain from northeastern Florida through the eastern Carolinas and southeastern Virginia in October 2016, leading to flooding that topped levels from Floyd along the Neuse River at Goldsboro and Kinston, North Carolina.

A truck drives through floodwaters from Hurricane Matthew in Lumberton, North Carolina, Wednesday, Oct. 12, 2016.
(AP Photo/Chuck Burton)

The other most recent example in this region was Hurricane Floyd in 1999, when torrential rain on ground saturated from Tropical Storm Dennis a few weeks prior led to massive flooding in North Carolina.

Incredibly, the rainfall totals from Florence may top those during Floyd in parts of North Carolina.

Hurricane Irene in 2011 produced a swath of heavy rain up the East Coast, but it is probably most memorable for the massive inland flooding it triggered in Vermont and other parts of New England and New York state.

Arguably, the most notorious inland Eastern flood event in recent memory was also from a remnant tropical cyclone, Agnes, in June 1972, which resulted in $2.1 billion of damage in the U.S., most of which came from inland flooding.

Catastrophic inland flooding is likely in some areas from Florence, featuring both short-term flash flooding and lingering mainstem river flooding that could last for weeks.

According to a National Hurricane Center study, roughly three of every four deaths in tropical cyclones in the U.S. are from water, either from storm surge (49 percent) or rainfall flooding (27 percent). Only 8 percent of U.S. deaths are from wind. 

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