South Carolina's Catastrophic Floods Caused By One of the Most Prolific Rainfall Events in Modern U.S. History
October eight 2015 Ten:15 PM EDT
A Different View Of The Rain Totals
The catastrophic floods striking South Carolina will go down in the history books, not only because of the lives they've taken or the destruction they've wrought, but also because of the sheer amount of rainfall. By the time the last raindrop is counted, the October two thousand fifteen storm will go down as one of the most prolific rainfall events in the modern history of the United States.
Rainfall totals from the early October storm have shattered or jeopardized innumerable records in South Carolina.
- The official statewide 24-hour rainfall record was exceeded in several locations; an official determination may take months to accomplish.
- The unofficial state record for 5-day total rainfall, which had stood for one hundred seven years, has been surpassed at more than a dozen reporting sites.
- The rainfall exceeded that of any tropical cyclone in South Carolina history.
- Seven sites with more than fifty years of data achieved their moistest Octobers on record.
- The October monthly precipitation record for any location in the state has likely been cracked.
Data are still being assimilated into the National Oceanic and Atmospheric Administration's database, but here is how the Carolinas flood disaster stacks up in various categories.
Greatest 24-Hour Rainfall Total
The National Oceanic and Atmospheric Administration (NOAA) has a process in place for vetting measurements of "potentially record-setting extreme meteorological elements" for each state. The process concentrates on a petite number of high-profile weather variables – all-time high and low temperatures , all-time greatest snow depth and 24-hour snowfall , and all-time most powerful 24-hour precipitation total.
Any time a standing record is called into question – either because of a fresh record-breaking event or fresh doubts about the scientific validity of the official record value – a State Climate Extremes Committee (SCEC) can be convened to investigate the matter.
For South Carolina, the standing 24-hour precipitation record was set during Hurricane Floyd when 14.80 inches of rain fell in Myrtle Beach on Sept. 16, 1999.
South Carolina's committee will surely be called upon to investigate the astronomical rainfall totals recorded this week, as some emerge to surpass the standing record.
One possibility is the Weather Underground individual weather station on White Birch Circle in Columbia , which reported Eighteen.71 inches of rain inbetween Trio:55 p.m. EDT on Oct. Three and the same time Oct. Four.
The site piled up 17.72 inches on Oct. Four itself, of which 15.12 inches – enough to break the 24-hour record – fell in less than ten hours during the morning. However, a neighboring site about a mile away received only seven inches of rain in forty eight hours Oct. 3-4. Such a acute difference may be evidence that one or both gauges is not decently calibrated.
In any case, several other sites may also have a case for claiming the fresh state record:
- 16.61 inches of rain inbetween midnight and ten p.m. Oct. Four along Gills Creek in Columbia, according to the National Weather Service. The ensuing flash flood was so violent that it ruined the official flood gauge there, but not before surpassing and almost doubling the previous all-time record crest .
- 15.70 inches of rain betwen 12:44 p.m. Oct. Three and 12:31 p.m. Oct. Four at the South Carolina Department of Transportation office in Kingstree, according to its Weather Underground individual weather station .
- 15.02 inches of rain on Oct. Four at the Weather Underground individual weather station in Dalzell , Sumter County.
Regardless of the state record, several individual cities and towns eyed unprecedented rainfall.
In fact, of the fifty nine South Carolina sites in NOAA's climate database with at least fifty years of weather observations, nine set all-time one-day records for the month of October. More impressively, six of those nine sites also broke their one-day rainfall records for any month.
Historic One-Day Rainfall Totals
Charleston International Airport, which is actually in North Charleston, led that group of long-time stations. Its Oct. Three total of 11.50 inches bested all other days in the site's 77-year period of weather data.
The process of confirming a fresh state record in a major category is not a quick one. When South Carolina's all-time high temperature record was challenged by two sites on June 29, 2012, the SCEC undertook an exhaustive investigation involving very detailed scrutiny of thermometers, instrument shelters and technical procedures involved in the observations. It wasn't until mid-October that the committee voted to recognize a fresh all-time record of one hundred thirteen degrees at the University of South Carolina in Columbia, and the final decision wasn't made public until mid-December of that year .
While South Carolina may eventually see a fresh state record, the national 24-hour rainfall record of forty two inches set in Alvin, Texas, will stand untouched. It was set during Tropical Storm Claudette in July 1979.
Greatest Five-Day Rainfall Total
Part of the reason the South Carolina floods became so catastrophic is that tropical downpours lashed the same areas for several days.
South Carolina Flood Rainfall Cylinders
While NOAA does not maintain official state rainfall records for intervals other than twenty four hours, its climate database permits us to make those comparisons on other time scales.
The early October storm deluged the Carolinas for the better part of five days, so we took a look at the moistest five-day intervals on record in South Carolina history. At the embark of this month, the top five were:
- 17.44 inches in downtown Greenville (Aug. 22-26, 1908)
- 17.37 inches in Kingstree (July 12-16, 1916)
- 17.08 inches at Charleston International Airport (July 8-12, 1973)
- 16.93 inches in Gillisonville (Aug. 27-31, 1898)
- 16.80 inches in Myrtle Beach (Sept. 15-19, 1999)
The one thousand nine hundred sixteen event in Kingstree is the highest valid rainfall total from a tropical cyclone in South Carolina history. It remains to be seen whether NOAA will consider rainfall from the two thousand fifteen flood to be associated with Hurricane Joaquin, since its role in the deluge was indirect.
Even tho’ fairly a bit of information hasn't yet made it into NOAA's database, this storm has already re-written the record books for South Carolina. As of Thursday afternoon, these are the moistest five-day intervals on record in South Carolina history – all of them from the latest storm:
Moistest Five-Day Periods in South Carolina
As more reports are submitted, verified and added to the NOAA database, the list resumes to evolve. As of Thursday evening, the five highest rainfall totals on record in South Carolina were these:
- 27.15 inches in the Park West neighborhood of Climb on Pleasant (Oct. 1-5, 2015)
- 23.76 inches on near Clark Sound on James Island in Charleston (Oct. 1-5, 2015)
- 23.50 inches at Georgetown County Airport in Georgetown (Oct. 1-5, 2015)
- 22.04 inches near the Whitehouse Plantation area of James Island in Charleston (Oct. 2-6, 2015)
- 21.57 inches near Wappoo Creek in Charleston (Oct. 2-6, 2015)
- Note: the 2nd and fourth locations on this list are less than one mile apart.
Some rural co-operative stations only report on a monthly basis, so there may yet be some staggering totals that won't inject the records until next month.
In all, more than forty reporting sites have cracked the one thousand nine hundred eight record from Greenville, including Charleston International Airport with 17.70 inches of rain from Sept. Thirty through Oct. Four.
These five-day totals stack up impressively against the all-time five-day rainfall records for other states in the region:
- Virginia: 20.96 inches in Colonial Beach set Sept. 6-10, 2011; NOAA officially recognizes this as the top rainfall total from Tropical Storm Lee that year.
- North Carolina: 24.06 inches near Southport set Sept. 15-19, 1999; this is the official top rainfall total in any state from Hurricane Floyd.
- Georgia: 27.85 inches in Americus set July 4-8, 1994; this is the official top rainfall total from slow-moving Tropical Storm Alberto that year.
- Florida: 27.84 inches in Fresh Smyrna Beach set May 19-23, 2009. The setup was similar to this week's disaster: strong high pressure over the Northeast, low pressure in the upper atmosphere over Florida, and a long fetch of onshore winds from the western Atlantic.
The extreme rainfall wasn't just limited to Charleston, either. Of South Carolina's forty six counties, nine – Charleston, Williamsburg, Georgetown, Horry, Berkeley, Sumter, Richland, Dorchester and Orangeburg – received at least twenty inches of rain at one or more rain gauges from this storm system.
Moistest October on Record in Six Cities
As if all those short-term rainfall records weren't enough, seven longer-term reporting stations in South Carolina have already logged their moistest October on record – with twenty six or more days to spare!
Perhaps the most devastating example is the co-operative observation site four miles west of Summerville, just north of Charleston. After one hundred seventeen years of recordkeeping, that site broke its previous record for the entire month of October (Ten.76 inches in 1968) less than a week into the fresh month. The month-to-date total of 17.95 inches through Oct. Six had already surpassed the old record by a margin of more than seven inches.
It's no coincidence that one of the very first areas to deal with swift-water rescues in South Carolina was that area west of Summerville in Dorchester County on Saturday night, Oct. Trio.
The nearby Charleston International Airport in North Charleston has also sealed the deal for October with 17.32 inches of rain during the very first week of the month.
Arguably most incredible of all, the co-operative site at Andrews, in northeast South Carolina, has recorded its moistest month ever since records began there in November 1962; at 20.05 inches, this month has out-deluged even September one thousand nine hundred ninety nine and September 1989, the months that brought Hurricane Floyd and Hurricane Hugo, respectively.
Fresh State October Rainfall Record?
There are two ways to look at the question of the "moistest October" in South Carolina history. One is to look at the statewide average, something NOAA will do in early November in its monthly State of the Climate report.
The other is to look at individual cities and observation sites. Prior to this storm, the standing October rainfall record for the state was 25.81 inches measured in Hilton Head in October 1994.
As mentioned above, one site in Climb on Pleasant site reported 27.15 inches of rain just in the very first five days of October, and that shows up to be a fresh record for the most rainfall during October at any individual reporting site in South Carolina.
The moistest calendar month on record at any location in South Carolina occurred in July 1916, when Kingstree picked up 31.13 inches of rain. That community was severely flooded again in this storm, and a Weather Underground rain gauge there (not included in NOAA's database) recorded 23.73 inches of rain during the very first five days of October.
South Carolina – s Catastrophic Floods Caused By One of the Most Prolific Rainfall Events in Modern U
South Carolina's Catastrophic Floods Caused By One of the Most Prolific Rainfall Events in Modern U.S. History
October eight 2015 Ten:15 PM EDT
A Different View Of The Rain Totals
The catastrophic floods striking South Carolina will go down in the history books, not only because of the lives they've taken or the destruction they've wrought, but also because of the sheer amount of rainfall. By the time the last raindrop is counted, the October two thousand fifteen storm will go down as one of the most prolific rainfall events in the modern history of the United States.
Rainfall totals from the early October storm have shattered or jeopardized uncountable records in South Carolina.
- The official statewide 24-hour rainfall record was exceeded in several locations; an official determination may take months to accomplish.
- The unofficial state record for 5-day total rainfall, which had stood for one hundred seven years, has been surpassed at more than a dozen reporting sites.
- The rainfall exceeded that of any tropical cyclone in South Carolina history.
- Seven sites with more than fifty years of data achieved their moistest Octobers on record.
- The October monthly precipitation record for any location in the state has likely been cracked.
Data are still being assimilated into the National Oceanic and Atmospheric Administration's database, but here is how the Carolinas flood disaster stacks up in various categories.
Greatest 24-Hour Rainfall Total
The National Oceanic and Atmospheric Administration (NOAA) has a process in place for vetting measurements of "potentially record-setting extreme meteorological elements" for each state. The process concentrates on a petite number of high-profile weather variables – all-time high and low temperatures , all-time greatest snow depth and 24-hour snowfall , and all-time most powerful 24-hour precipitation total.
Any time a standing record is called into question – either because of a fresh record-breaking event or fresh doubts about the scientific validity of the official record value – a State Climate Extremes Committee (SCEC) can be convened to investigate the matter.
For South Carolina, the standing 24-hour precipitation record was set during Hurricane Floyd when 14.80 inches of rain fell in Myrtle Beach on Sept. 16, 1999.
South Carolina's committee will surely be called upon to investigate the astronomical rainfall totals recorded this week, as some emerge to surpass the standing record.
One possibility is the Weather Underground private weather station on White Birch Circle in Columbia , which reported Legitimate.71 inches of rain inbetween Trio:55 p.m. EDT on Oct. Three and the same time Oct. Four.
The site piled up 17.72 inches on Oct. Four itself, of which 15.12 inches – enough to break the 24-hour record – fell in less than ten hours during the morning. However, a neighboring site about a mile away received only seven inches of rain in forty eight hours Oct. 3-4. Such a acute difference may be evidence that one or both gauges is not decently calibrated.
In any case, several other sites may also have a case for claiming the fresh state record:
- 16.61 inches of rain inbetween midnight and ten p.m. Oct. Four along Gills Creek in Columbia, according to the National Weather Service. The ensuing flash flood was so violent that it demolished the official flood gauge there, but not before surpassing and almost doubling the previous all-time record crest .
- 15.70 inches of rain betwen 12:44 p.m. Oct. Three and 12:31 p.m. Oct. Four at the South Carolina Department of Transportation office in Kingstree, according to its Weather Underground private weather station .
- 15.02 inches of rain on Oct. Four at the Weather Underground private weather station in Dalzell , Sumter County.
Regardless of the state record, several individual cities and towns spotted unprecedented rainfall.
In fact, of the fifty nine South Carolina sites in NOAA's climate database with at least fifty years of weather observations, nine set all-time one-day records for the month of October. More impressively, six of those nine sites also broke their one-day rainfall records for any month.
Historic One-Day Rainfall Totals
Charleston International Airport, which is actually in North Charleston, led that group of long-time stations. Its Oct. Three total of 11.50 inches bested all other days in the site's 77-year period of weather data.
The process of confirming a fresh state record in a major category is not a quick one. When South Carolina's all-time high temperature record was challenged by two sites on June 29, 2012, the SCEC undertook an exhaustive investigation involving very detailed scrutiny of thermometers, instrument shelters and technical procedures involved in the observations. It wasn't until mid-October that the committee voted to recognize a fresh all-time record of one hundred thirteen degrees at the University of South Carolina in Columbia, and the final decision wasn't made public until mid-December of that year .
While South Carolina may eventually see a fresh state record, the national 24-hour rainfall record of forty two inches set in Alvin, Texas, will stand untouched. It was set during Tropical Storm Claudette in July 1979.
Greatest Five-Day Rainfall Total
Part of the reason the South Carolina floods became so catastrophic is that tropical downpours lashed the same areas for several days.
South Carolina Flood Rainfall Cylinders
While NOAA does not maintain official state rainfall records for intervals other than twenty four hours, its climate database permits us to make those comparisons on other time scales.
The early October storm deluged the Carolinas for the better part of five days, so we took a look at the moistest five-day intervals on record in South Carolina history. At the begin of this month, the top five were:
- 17.44 inches in downtown Greenville (Aug. 22-26, 1908)
- 17.37 inches in Kingstree (July 12-16, 1916)
- 17.08 inches at Charleston International Airport (July 8-12, 1973)
- 16.93 inches in Gillisonville (Aug. 27-31, 1898)
- 16.80 inches in Myrtle Beach (Sept. 15-19, 1999)
The one thousand nine hundred sixteen event in Kingstree is the highest valid rainfall total from a tropical cyclone in South Carolina history. It remains to be seen whether NOAA will consider rainfall from the two thousand fifteen flood to be associated with Hurricane Joaquin, since its role in the deluge was indirect.
Even however fairly a bit of information hasn't yet made it into NOAA's database, this storm has already re-written the record books for South Carolina. As of Thursday afternoon, these are the moistest five-day intervals on record in South Carolina history – all of them from the latest storm:
Moistest Five-Day Periods in South Carolina
As more reports are submitted, verified and added to the NOAA database, the list resumes to evolve. As of Thursday evening, the five highest rainfall totals on record in South Carolina were these:
- 27.15 inches in the Park West neighborhood of Climb on Pleasant (Oct. 1-5, 2015)
- 23.76 inches on near Clark Sound on James Island in Charleston (Oct. 1-5, 2015)
- 23.50 inches at Georgetown County Airport in Georgetown (Oct. 1-5, 2015)
- 22.04 inches near the Whitehouse Plantation area of James Island in Charleston (Oct. 2-6, 2015)
- 21.57 inches near Wappoo Creek in Charleston (Oct. 2-6, 2015)
- Note: the 2nd and fourth locations on this list are less than one mile apart.
Some rural co-operative stations only report on a monthly basis, so there may yet be some staggering totals that won't inject the records until next month.
In all, more than forty reporting sites have cracked the one thousand nine hundred eight record from Greenville, including Charleston International Airport with 17.70 inches of rain from Sept. Thirty through Oct. Four.
These five-day totals stack up impressively against the all-time five-day rainfall records for other states in the region:
- Virginia: 20.96 inches in Colonial Beach set Sept. 6-10, 2011; NOAA officially recognizes this as the top rainfall total from Tropical Storm Lee that year.
- North Carolina: 24.06 inches near Southport set Sept. 15-19, 1999; this is the official top rainfall total in any state from Hurricane Floyd.
- Georgia: 27.85 inches in Americus set July 4-8, 1994; this is the official top rainfall total from slow-moving Tropical Storm Alberto that year.
- Florida: 27.84 inches in Fresh Smyrna Beach set May 19-23, 2009. The setup was similar to this week's disaster: strong high pressure over the Northeast, low pressure in the upper atmosphere over Florida, and a long fetch of onshore winds from the western Atlantic.
The extreme rainfall wasn't just restricted to Charleston, either. Of South Carolina's forty six counties, nine – Charleston, Williamsburg, Georgetown, Horry, Berkeley, Sumter, Richland, Dorchester and Orangeburg – received at least twenty inches of rain at one or more rain gauges from this storm system.
Moistest October on Record in Six Cities
As if all those short-term rainfall records weren't enough, seven longer-term reporting stations in South Carolina have already logged their moistest October on record – with twenty six or more days to spare!
Perhaps the most devastating example is the co-operative observation site four miles west of Summerville, just north of Charleston. After one hundred seventeen years of recordkeeping, that site broke its previous record for the entire month of October (Ten.76 inches in 1968) less than a week into the fresh month. The month-to-date total of 17.95 inches through Oct. Six had already surpassed the old record by a margin of more than seven inches.
It's no coincidence that one of the very first areas to deal with swift-water rescues in South Carolina was that area west of Summerville in Dorchester County on Saturday night, Oct. Trio.
The nearby Charleston International Airport in North Charleston has also sealed the deal for October with 17.32 inches of rain during the very first week of the month.
Arguably most exceptional of all, the co-operative site at Andrews, in northeast South Carolina, has recorded its moistest month ever since records began there in November 1962; at 20.05 inches, this month has out-deluged even September one thousand nine hundred ninety nine and September 1989, the months that brought Hurricane Floyd and Hurricane Hugo, respectively.
Fresh State October Rainfall Record?
There are two ways to look at the question of the "moistest October" in South Carolina history. One is to look at the statewide average, something NOAA will do in early November in its monthly State of the Climate report.
The other is to look at individual cities and observation sites. Prior to this storm, the standing October rainfall record for the state was 25.81 inches measured in Hilton Head in October 1994.
As mentioned above, one site in Climb on Pleasant site reported 27.15 inches of rain just in the very first five days of October, and that emerges to be a fresh record for the most rainfall during October at any individual reporting site in South Carolina.
The moistest calendar month on record at any location in South Carolina occurred in July 1916, when Kingstree picked up 31.13 inches of rain. That community was severely flooded again in this storm, and a Weather Underground rain gauge there (not included in NOAA's database) recorded 23.73 inches of rain during the very first five days of October.