South Carolina Hurricane Climatology
Introduction
A Tropical cyclone is a non-frontal, low pressure system that develops over tropical or subtropical waters and has a definite organized cyclonic (counterclockwise) circulation. On the basis of the sustained (1-minute average) wind speed near the center of the storm, tropical cyclones are classified as: Tropical Depression, less than 34 knots (less than 39 miles per hour); Tropical Storms, 34 to 63 knots (39-73 miles per hour); or Hurricanes, greater than 63 knots (greater than 73 miles per hour). Only tropical storms and hurricanes are assigned names.
Geographic regions affected by tropical cyclones are known as tropical-cyclone basins. The Atlantic
tropical-cyclone basin is one of six in the world and includes much of the North Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico. (see Figure 1.)
The official Atlantic hurricane "season" begins June 1 and ends November 30 each year; however, the season can begin earlier and end later than its official time.
Early season tropical cyclones generally form in the western Caribbean Sea and the Gulf of Mexico. By the
end of June or in early July, the area of formation begins shifting eastward, accompanied by a slight decline in overall storm frequency. By late July, the area of formation has shifted farther eastward and storm frequency increases.
In late August, tropical cyclones are forming over a broad area of the eastern Atlantic, extending eastward to the area of the Cape Verde Islands off the coast of Africa. The period from about August 20 through about September 15 encompasses the maximum of these Cape Verde storms. Most Cape Verde storms cross-vast areas of the Atlantic Ocean before dying in the North Atlantic or making landfall in northern Europe. Those, which make landfall in the United States, are generally severe.Since 1906, twelve "Cape Verde storms" have mad landfall in the United States, eight of them being Category 3 or 4 hurricanes.
By Mid-September, storm frequency begins to decline, the formative area retreats westward to the Caribbean Sea and the Gulf of Mexico, and storm frequency in that area increases. Usually, by mid-November tropical-cyclone occurrence in the South Atlantic has ceased.
Records of tropical-cyclone occurrences in the Atlantic tropical-cyclone basin are kept by the National Climatic Data Center in Asheville, North Carolina, in cooperation with the National Hurricane Center in Miami, Florida.Records are updated annually and are available from the National Climatic Data Center. For the 115-year period 1871-1985, a total of 928 tropical cyclones were recorded in the Atlantic tropical-cyclone basin.For some of those years, however, the existing data does not allow accurate determinations of the types of tropical cyclones (tropical storms or hurricanes) nor the intensities of the storms. Other researchers have compiled fragmentary data on tropical cyclones dating back to the 15th Century. This information is available in some local libraries.
Historical Hurricanes in South Carolina
Despite the landfall average of once in every four to five year, hurricanes and tropical storms are irregular visitors to coastal South Carolina. In the period, 1901-1985, only 22 tropical cyclones (tropical storms or hurricanes) have made landfall on the South Carolina coast. Of these, only eight were of Category 2 to Category 4 intensity. (see Appendix). Since 1900, no Category 5 hurricanes has hit South Carolina or storms; there have been one Category 4 (Hazel, 1954) and two Category 3 hurricanes (September 17, 1945, and Gracie, 1959). It is possible that the "Great Storm of 1893" that struck the southern on coast on August 20 of that year was at least a Category 4 storm, but there is no way of knowing, since measures of tropical-cyclone intensity are not available for storms before 1900.
In the Colonial period tropical storms and hurricanes were known as "September gales," probably because the ones people remembered and wrote about were those which damaged or destroyed crops just before they were to be harvested.
One such storm that struck Charles Town on September 25, 1686, was "wonderfully horrid and destructive...Corne is all beaten down and lyes rotting on the ground... Aboundance of our hoggs and Cattle were killed in the Tempest by the falls of Trees..." The writer goes on to say that the storm also prevented a Spanish assault upon Charles Town by destroying one of their galleys and killing the commander-in-chief.
In autumn of 1700, "a dreadful hurricane happened at Charles Town which did great damage and threatened that total destruction of the Town, the lands on which it is built being low and level and not many feet about high water mark, the swelling sea rushed in with amazing impetuosity, and obliged the inhabitants
to fly to shelter..." A ship, Rising Sun, out of Glasgow and filled with settlers had made port just prior to the storm's landfall. It was dashed to pieces and all on board perished.
Of a storm which passes inland along the coast September 7-9, 1854, Adele Pettigru Allston wrote from Pawleys Island, "The tide was higher than has been known since the storm of 1822. Harvest had just commenced and that damage to the crops in immense. From Waverly to Pee Dee not a bank nor any appearance of land was to be seen...(just) one rolling, dashing Sea, and the water was Salt as the Sea."
By 1893, major population centers could be telegraphically alerted to storms moving along the coast, but there were no warnings for the Sea Islands and other isolated areas. The "Great Storm of 1893" struck the south coast at high tide on August 28, pushing an enormous storm surge ahead of it and creating a "tidal wave" that
swept over and submerged whole islands. Maximum winds in the Beaufort area were reported at 125 miles per hour, those in Charleston at 120 miles per hour. Water from the first wave probably stacked up in the marshes, held there by the wind until the next high tide, which was after the storm had passed. Lowered barometric pressure and the amount of "stacked" water created resonance-effect destruction equal to that of the "tidal wave."
At least 2,000 people lost their lives, and an estimated 20,000-30,000 were left homeless and with no mean of subsistence. Property damage was estimated at $10 million, equal to $119, 330, 000 in 1985 dollars.
Hazel (October 1954) and Gracie (September 1959) have been the most memorable storms in recent years. Hazel,
a Category 4 storm, made landfall near Little River, S.C., with 106-miles per hour winds and tides up to 16.9 feet. One
person was killed and damage was estimated at $27 million.
Gracie, a Category 3 hurricane, made landfall on St. Helena Island and continued toward the north-northwest, maintaining hurricane strength for more than 100 miles inland. Damage of disaster proportions occurred along the coast from Beaufort to Charleston. Heavy rains caused flooding through much of the State and crop damage was severe, but there was no loss of life.
Hugo (September 1989) made landfall as a Category 4 Hurricane near Sullivan's Island and immediately was downgraded to Category 3. It continued on a northwest track at 25-30 miles per hour and maintained hurricane force winds
as far inland as Sumter. Hugo exited the State southwest of Charlotte, N.C., before sunrise on September 22. The hurricane caused 13 directly related deaths and 22 indirectly related deaths, and it injured several hundred people in South Carolina. Damage in the State was estimated to exceed $7 billion, including $2 billion in crop damage. The forests in 36 counties along the path of the storm sustained major damage.
Although no hurricanes made landfall in South Carolina from 1990 through 2001, Hurricane Floyd (September 1999) was a very large storm that came very close, making landfall near Cape Fear, N.C. Heavy rain of more than 15 inches fell in parts of Horry County, S.C., causing major flooding along the Waccamaw River in and around the city of Conway for a month.
Saffir-Simpson Hurricane Scale
Category 1: Winds 74 to 95 miles per hour. Damage primarily to shrubbery, tree foliage, and unanchored mobile homes; no real damage to other structures.Some damage to poorly constructed signs. Minor pier damage; some small craft in exposed anchorages torn from moorings. Storm surges 4 to 5 feet above normal tide heights; low-lying coastal roads inundated.
Category 2: Winds 96 to 110 miles per hour. Considerable damage to shrubbery and tree foliage, some trees blown down. Major damage to exposed mobile homes; no major damage to buildings; some damage to roofing materials of buildings; some window and door damage. Extensive damage to poorly constructed signs. Considerable damage to piers, marinas flooded. Small craft in protected anchorages may be torn from moorings. Storm surges 6 to 8 feet above normal tide heights.Coastal roads and low-lying evacuation routes inland cut by rising water 2 to 4 hours before expected landfall. Evacuation of some shoreline and low-lying island areas necessary.
Category 3: Winds 111 to 130 miles per hour. Foliage torn from trees, large trees blown down. Mobile
homes destroyed, some structural damage to small buildings; some damage to roofing materials of buildings; some window and door damage. Practically all poorly constructed signs blown down. Storm surges 9 to 12 feet above normal tide heights. Low-lying evacuation routes inland cut by rising water 3 to 5 hours before expected landfall. Serious coastal flooding; many smaller structures near the coast destroyed, larger ones damaged by battering waves and floating debris. Inland flooding of areas less than 5 feet elevation; evacuation of low-lying
near shore areas necessary.
Category 4: Winds 131 to 155 miles per hour.Shrubs and trees blown down; all signs down. Complete destruction of mobile homes. Extensive damage to roofing materials, windows and doors. Complete failure of roofs on small buildings. Major damage to lower floors of near-shore structures due to flooding and battering by waves and floating debris. Storm surges 13 to 18 feet above normal tide heights.Low-lying evacuation routes inland cut by rising water 3 to 5 hours before expected landfall. Extensive inland flooding of areas less than 10 feet elevation. Major erosion of beaches. Evacuation of all residences in areas less than 10 ft. elevation required.
Category 5: Winds greater than 155 miles per hour. Shrubs and trees blown down; all signs down. Extensive shattering of glass in windows and doors; complete failure of roofs on many residences and industrial buildings. Complete destruction of mobile homes; small buildings overturned or blown down; some complete failures of other structures.Low-lying evacuation routes inland cut by floodwaters 3 to 5 hours before landfall. Storm surge greater that 18 feet about normal tide heights. Some islands completely swept by storm surge. Major damage to lower floors of all structures less than 15 feet above sea level within half-mile of shore. Evacuation of all residences in low-lying areas within 5-10 miles of shore possibly required.
SAFFIR/SIMPSON HURRICANE SCALE WITH CENTRAL BAROMETRIC PRESSURE RANGES
| CATEGORY |
CENTRAL
PRESSURE
(Millibars) |
CENTRAL
PRESSURE
(Inches) |
WINDS
(MPH) |
SURGE
(Feet) |
DAMAGE |
|---|
| 1 |
>980 |
>29.94 |
74-95 |
4-5 |
Minimal |
| 2 |
965-979 |
28.50-28.91 |
96-110 |
6-8 |
Moderate |
| 3 |
945-964 |
27.91-28.47 |
111-130 |
9-12 |
Extensive |
| 4 |
920-944 |
27.17-27.88 |
131-155 |
13-18 |
Extreme |
| 5 |
<920 |
<27.17 |
155+ |
>18 |
Catastrophic |
Tropical Weather Terminology
The Official Hurricane Season begins June 1 and ends November 30. Occasionally, tropical systems begin earlier and end later. A tropical cyclone is the general term for all cyclone circulations originating over tropical waters.
Watch and Warning Definition
| Tropical System |
Definition |
|---|
| Tropical disturbance |
A moving area of thunderstorms over the tropics maintaining its identity for 24 hours or more. |
| Tropical depression |
Thunderstorms with rotary surface circulation with winds up to 38 miles per hour. |
| Tropical Storm |
Thunderstorms with distinct rotary surface circulation with winds 39 to 73 miles per hour. |
| Hurricane |
Pronounced rotary circulation with sustained surface winds of 74 miles per hour or greater. |
| Hurricane Watch |
Issued for coastal areas when there is a threat within 24 to 36 hours. |
| Hurricane Warning |
Hurricane conditions expected within 24 hours or less. |
Remember, hurricanes produce life threatening winds, tornadoes, and other unforeseen dangers.
Be prepared to save property and lives.
Notable South Carolina Hurricanes
| Date |
Hurricane Data |
|---|
| August 28, 1893 |
Landfall near South Carolina / Georgia border, winds estimated at over 120 miles per hour, loss of life estimated at more than 2,000. |
| July 14, 1916 |
Landfall near Bulls Bay, South Carolina, winds estimated at over 80 miles per hour, slow-moving torrential rains produced eastern South Carolina's worst flood. Effingham, South Carolina, 13.25 inches of rain in 24 hours. |
| August 11, 1940 |
Landfall near Beaufort, South Carolina, winds 105 miles per hour, loss of life 34. Beaufort, South Carolina, 10.84 inches of rain in 24 hours. |
| October 15, 1954 |
"Hazel"- Landfall near South Carolina / North Carolina border, winds at Myrtle Beach reached 106 miles per hour, loss of life 1, oceanfront property from Pawleys Island, South Carolina northward destroyed. Storm surge 17 feet. Georgetown, South Carolina, 8.80 inches of rain in 24 hours. |
| September 29, 1959 |
"Gracie"- Landfall at St. Helena Island, South Carolina. Marine Corps Auxilary Air Station recorded gust of 138 miles per hour. Heavy flooding from 8 inches of rain (Walterboro, 8.30 inches in 24 hours). |
| September 21, 1989 |
"Hugo"- Landfall at Isle of Palms, South Carolina, winds 140 miles per hour with gust over 160 miles per hour. Costliest storm in South Carolina history at over 6 billion dollars, 35 related fatalities, storm surge 20+ feet. Severe inland damage as winds gusting to 109 miles per hour at Shaw Air Force Base, Sumter, South Carolina. |
