After more than 5 1-in-1000 flood events in August 2022, now rainfall in parts of northwest Georgia Sunday has been so heavy, that weather specialists estimate it is at least a one-in-200 year event. Stop the weather warfare!
“Portions of Chattooga and Floyd counties have received 10-13 inches, with more rain coming. These amounts have resulted in catastrophic flash flooding and a Flash Flood Emergency continues in that area,” the National Weather Service office in Atlanta said Sunday.
Rainfall of as much as 2 inches an hour are possible into Sunday evening, the weather service said, and more is expected into Tuesday.
Due to the “locally extreme rainfall” and additional rain forecast, the Weather Prediction Center upgraded to a level 3 out of 4 “moderate” risk for excessive rainfall Sunday afternoon through early Monday morning.
Georgia Gov. Brian Kemp issued a state of emergency order Sunday afternoon for severe flooding in Chattooga and Floyd counties. An estimated foot of rain in some places is expected to cause rivers to rapidly rise, according to the order.
?#BREAKING: Flash Flood Emergency for Chattooga GA
The National weather service has issued a Flash Flood Emergency for chattooga county GA where multiple reports of significant flooding is taking place as 6-10+ inches of rain has already fallen pic.twitter.com/W7WqUbATG8
— R A W S A L E R T S (@rawsalerts) September 4, 2022
“Preliminary assessments from county emergency management agencies and the Georgia Emergency Management and Homeland Security Agency indicate a need for assistance in the impacted counties,” the order read.
The area, including Summerville, Lyerly and the James H. Floyd State Park, is under a flash flood emergency warning Sunday.
America’s summer of floods continues.
Northwest Georgia’s Chattooga County has been slammed by 8-12 inches of rain in the last 12 hours leading to catastrophic flooding.
This is yet another 1-in-200+ year rain event. pic.twitter.com/CXpdikI2SJ
— Colin McCarthy (@US_Stormwatch) September 4, 2022
“This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW! Life threatening flash flooding of low water crossings, small creeks and streams, urban areas, highways, streets and underpasses,” the warning from the weather service said.
Jennifer Hurley, who has a salon in downtown Summerville, said it took her hours to get to her business because of flooding downtown. Her salon was among the businesses flooded in the town.
DRONE VIDEO: @GovKemp has declared a State of Emergency in Chattooga and Floyd Counties. Here is #SKYFOXDrone video captured in Summerville, Georgia that shows some of the damage in the hard hit communities. Georgia’s first responders are hard at work right now. @FOX5Atlanta #wx pic.twitter.com/K0aTtMipcn
— Billy Heath III (@BillyHeathFOX5) September 4, 2022
The Chattooga County Emergency Management Agency said more rain may be coming and urged residents not to venture out.
“We are expecting at least 2 more inches of rain today and we are asking everyone to PLEASE stay home and do not travel unless absolutely necessary,” the agency said on Facebook.
Here’s some of the images from Chattooga County, #Georgia where very significant flash flooding is ongoing still. Residents in Summerville are advised to boil water now. GA’s Governor had declared a state of emergency for the county + Floyd County as well. #GAwx #flood pic.twitter.com/4ZDRgajOBt
— Vortix ♦️CODE RED♦️ (@VortixWx) September 4, 2022
What ‘1-in-1,000-year’ means?
The term “1-in-1,000-year” rainfall event or flood event may sound like something that is only forecast to occur once every thousand years and that once you experience such an event, you’d expect to be in the clear until the year 3022.
That’s not quite how it works. Instead, that term is given to an event that forecasters deem only to have a 0.1% chance of occurring in any given year – a 1 in 1,000 chance. An 0.5% chance is deemed a “1-in-500-year” event, while a 1% chance is a “1-in-100-year” event, and so forth.
The National Oceanic and Atmospheric Administration’s Office of Water Prediction oversees researching historical rainfall events across the nation to classify how much rain needs to fall within certain periods (such as an hour, several hours, or days) relative to their climate averages to reach each probability threshold. For example, it took far less rain in Death Valley (just under 1.5 inches) than St. Louis (over 9 inches) to reach the 0.1% probability threshold.
With so many of what are supposed to be exceedingly rare events occurring with much more frequency, you might be wondering if the calculations are off. [CNN]