1947 Florida–Georgia hurricane

Add links
Source: Wikipedia, the free encyclopedia.

Hurricane Nine (King)
Surface weather analysis of the hurricane nearing Georgia on October 15
Meteorological history
FormedOctober 9, 1947 (October 9, 1947)
DissipatedOctober 16, 1947 (October 16, 1947)
Category 2 hurricane
1-minute sustained (SSHWS/NWS)
Highest winds105 mph (165 km/h)
Lowest pressure965 mbar (hPa); 28.50 inHg
(estimated)
Overall effects
Fatalities1 direct
Damage$3.26 million (1947 USD)
($44.5 million in 2024 USD)
Areas affected
IBTrACSEdit this at Wikidata
Part of the 1947 Atlantic hurricane season

The 1947 Florida–Georgia hurricane (

north by west until a few days later it struck western Cuba. The cyclone then turned sharply to the northeast, accelerated, and strengthened to a hurricane, within 30 hours crossing the southern Florida peninsula. Across South Florida, the storm produced widespread rainfall of up to 15 inches (380 mm) and severe flooding, among the worst ever recorded in the area, that led to efforts by the United States Congress
to improve drainage in the region.

Once over the Atlantic Ocean on October 13, the storm made history when it was the first to be targeted for modification by government and private agencies; dry ice was spread by airplanes throughout the storm in an unsuccessful effort to weaken the hurricane, though changes in the track were initially blamed upon the experiment. On the same day as that of the seeding, the cyclone slowed dramatically and turned westward, making landfall on the morning of October 15 south of Savannah, Georgia. Across the U.S. states of Georgia and South Carolina, the small hurricane produced tides up to 12 feet (3.7 m) and significant damage to 1,500 structures, but the death toll was limited to one person. The system dissipated the next day over Alabama, having caused $3.26 million in losses along its path.[nb 2]

Meteorological history

Map plotting the storm's track and intensity, according to the Saffir–Simpson scale
Map key
Saffir–Simpson scale
  Tropical depression (≤38 mph, ≤62 km/h)
  Tropical storm (39–73 mph, 63–118 km/h)
  Category 1 (74–95 mph, 119–153 km/h)
  Category 2 (96–110 mph, 154–177 km/h)
  Category 3 (111–129 mph, 178–208 km/h)
  Category 4 (130–156 mph, 209–251 km/h)
  Category 5 (≥157 mph, ≥252 km/h)
  Unknown
Storm type
triangle Extratropical cyclone, remnant low, tropical disturbance, or monsoon depression

At 18:00 

Isla de Providencia, Colombia, near 13°30′N 82°18′W / 13.5°N 82.3°W / 13.5; -82.3.[4][5] Moving generally west of due north, the depression gradually strengthened, becoming a tropical storm a day later. At 15:30 UTC on October 10, the Hurricane Hunters—reconnaissance aircraft—first intercepted the storm, registering a pressure of 1,000 mb (30 inHg), which suggested maximum sustained winds of 54 mph (87 km/h). Afterward, the storm began curving east of due north, while nearing the island of Cuba. At 07:00 UTC October 11, the deepening tropical cyclone made landfall near La Coloma, Pinar del Río Province, with winds of 65 mph (100 km/h). After crossing the western portion of the island, the cyclone underwent robust intensification over the southeastern Gulf of Mexico, with most of its strengthening occurring in under four hours.[6][7] At 17:16 UTC aircraft entered the eye of the storm and measured a pressure of 983 mb (29.0 inHg), which corresponded to winds of 85 mph (140 km/h), making the storm equivalent to a Category 1 hurricane on the present-day Saffir–Simpson scale. The cyclone then angled sharply northeastward, passing near the Dry Tortugas en route to peninsular Florida. At 02:00 UTC on October 12, the hurricane impacted Southwest Florida north of Cape Sable with a slightly stronger intensity of 975 mb (28.8 inHg), along with winds of 90 mph (150 km/h);[8] the estimated pressure was based on a barometric measurement of 29.00 inHg (982 mb) taken at 07:00 UTC in Fort Lauderdale, on the edge of the eye, that was "'still falling'" at the time.[9][10] Then a smaller-than-average storm, it crossed the mostly uninhabited Everglades and passed over the Miami metropolitan area between Fort Lauderdale and Pompano Beach.[11][nb 3]

Shortly before 08:00 UTC it entered the Atlantic Ocean near Hillsboro Inlet Light, which experienced the center of a hurricane for the second time in a month, with winds of 80 mph (130 km/h).[12] After leaving South Florida, the hurricane passed north of the Bahamas while gradually weakening. By 00:00 UTC on October 13, the cyclone degenerated into a strong tropical storm, but regained hurricane status 12 hours later. Over the next day, the storm slowed substantially and began veering landward, executing a semicircular turn northward and westward, a trajectory that threatened the Southeastern United States.[4] During the night of October 13–14 a dearth of in-situ observations prevented forecasters from appraising its exact location and movement.[13] At this time reconnaissance aircraft penetrating the storm reported winds of up to 55 kn (63 mph; 102 km/h), and data from the aircraft suggested the ill-defined center "split in two".[14][nb 4] The secondary center meandered westward and became dominant on October 14, while slowly consolidating and intensifying. Late that day aircraft reported peak winds of 80 kn (92 mph; 150 km/h) in the storm. At 00:00 UTC on October 15, the cyclone intensified into the equivalent of a low-end Category 2 hurricane, and began accelerating westward toward Georgia. Six hours later it attained its peak of 105 mph (165 km/h), which it maintained until landfall around 11:00 UTC near Ossabaw Island, approximately 15 mi (24 km) south of Savannah.[4][8] The lowest pressure in the eye at landfall was estimated to have been near 965 mb (28.5 inHg), based in part on a report from a ship just offshore more than eight hours earlier.[9] At the time, the coverage of hurricane-force winds was small, extending about 20 miles (32 km) in all directions from the eye.[16] The storm weakened rapidly as it crossed inland over Georgia, and by 00:00 UTC on October 16 it weakened to a tropical storm, dissipating 18 hours later over Alabama.[4]

Preparations

On October 10, watercraft in the

Key West.[19] On October 12, warnings were extended from the Miami metropolitan area to Vero Beach. A pair of 75-car trains were dispatched to evacuate the Lake Okeechobee area. Airline traffic out of Jacksonville was halted, and several hundred vessels sought shelter in the Miami River.[20] Owing to short notice of the storm, only an estimated 10% of businesses in Miami had erected shutters.[21]

Impact

Cuba and Florida

In Cuba, the cyclone generated gust of up to 57 mph (92 km/h) at Batista Field, near Havana.[7]

Surface weather analysis of the storm over South Florida on October 12

Upon striking southernmost Florida, the cyclone only produced $75,000 in wind-related losses, largely due to its having struck an area hit by the more powerful September hurricane.[16][12] Peak winds in Florida were unofficially estimated to have reached 95 mph (153 km/h) around Cape Sable, the area where the storm made landfall. At the Dry Tortugas, wind instruments reported readings up to 84 mph (135 km/h) before failing due to "'friction from lack of oil'"; higher winds, unofficially estimated to have reached 150 mph (240 km/h), were believed to have occurred thereafter.[22][7] An elevated anemometer at the Dry Tortugas Light, on Loggerhead Key, measured gusts of 125 to 140 mph (201 to 225 km/h) prior to its destruction.[nb 5] An observer at Fort Jefferson reported that the winds lofted small pine trees.[20][11] Elsewhere in South Florida, the U.S. Weather Bureau Air Station at Miami International Airport reported sustained winds of 80 mph (130 km/h), while the Weather Bureau Office in downtown Miami recorded peak winds of 62 mph (100 km/h). In the 7-mile (11 km) distance between the two stations, atmospheric pressure varied 3 mb (0.089 inHg), but the lowest pressure was not below 995.3 mb (29.39 inHg).[7]

Total rainfall from the storm in Florida

Region-wide, the hurricane produced significant

Everglades City.[24] Due to the floods, septic tanks overflowed, leaving canal banks and patches of ground isolated by floodwaters; reportedly, U.S. Route 1, locally called Federal Highway and built largely upon the Atlantic coastal ridge—the highest elevation in South Florida—was flooded out between Miami and Fort Lauderdale.[29][24] Having been isolated by the floods, deer, rattlesnakes, and other wildlife, along with horses and cattle, sought shelter upon the remaining exposed ground, particularly levee banks.[29][30]

The flooding that resulted from the storm and the earlier September hurricane was among the worst ever recorded in South Florida and became known as the "Flood of 1947" or, as the South Florida Sun-Sentinel newspaper in 1990 called it, "the Great South Florida Flood."

Orlando to the Florida Keys.[30] South of Lake Okeechobee, a 20-to-40-mile-wide (32 to 64 km), 1⁄2-to-10-foot-deep (0.15 to 3.05 m) sheet of standing water inundated much of the region, including the Everglades.[27] In the region, 5,000,000 acres (2,000,000 ha; 7,800 sq mi; 20,000 km2) of land were flooded as abnormally high coastal tides prevented water from being released through canals to the Atlantic Ocean.[30] The flooding divided many communities: near Fort Lauderdale, a temporary dam that had been erected by the U.S. Army Corps of Engineers to protect Davie—a town in which 90% of the homes by the end of October were at least partially submerged[27]—lowered waters in some areas but merely diverted them to others, flooding a neighborhood and leading to angry complaints by residents; the situation worsened after the October hurricane produced even more rain over flooded South Florida.[30]

The storm also generated many tornadoes in South Florida.[31] One of the twisters downed trees and damaged a home at Redlands.[20] Another, estimated to have been an F2, unroofed a pair of homes in Miami.[32]

Georgia and South Carolina

Upon making landfall, the storm produced high tides of up to 12 ft (3.7 m) at Parris Island, South Carolina, and 9 ft (2.7 m) at Charleston, South Carolina. Up to 1,500 or more buildings were significantly damaged due to wind gusts that reached 95 mph (153 km/h) at Savannah, Georgia. One person died due to high tides preceding the storm. Total property losses in Georgia and South Carolina reached $2,185,000 (1947 USD).[31]

Aftermath

In South Florida, the flooding from the September and October hurricanes led to the creation in 1949 of what is now the South Florida Water Management District, which under a Congressional plan was entrusted with the task of preventing a recurrence of significant flooding by forming an improved flood-control system to modulate the water table and by providing suitable water levels with which to water crops, prevent saltwater intrusion, and support recreational opportunities as well as the growing South Florida communities.[27][29][30] Large pumping systems were constructed, along with numerous new levees and canals, to mitigate the risk of large-scale flooding, yet population growth since the late 1940s is believed to have reduced the extent of vacant lands needed for effective drainage, thereby increasing the risk of damage during a flood similar to that of 1947.[24] In his 1974 book Beyond the Fourth Generation, former EDD Chief Engineer Lamar Johnson voiced his concerns about large-scale development near the levees, which separate the Everglades water conservation areas from the Miami metropolitan area. Johnson wrote, "It is my opinion...that anytime that area gets a foot or more of rainfall overnight, the shades of 1947's flood will be with them again."[33]

The cyclone was historically significant in that it was the first tropical cyclone to be modified as part of a multi-year operation called Project Cirrus.[34][35] In July 1946, General Electric (GE) scientists concluded after experimentation that dry ice seeding could induce heavy rainfall and thus ultimately weaken storms by cooling temperatures in the eye. To undertake Project Cirrus, GE, the United States Army Signal Corps, the Office of Naval Research, and the U.S. Weather Bureau functioned jointly on research and planning.[36][37] A pair of B-17s and a B-29 of the Hurricane Hunters were dispatched from MacDill Air Force Base.[38] Early on October 13, 1947, 200 pounds (3,200 oz) of dry ice were dropped throughout the storm, then located about 350 mi (560 km) east of Jacksonville, Florida. While the appearance of the clouds changed, the initial results of the seeding were inconclusive.[39] Shortly after the seeding took place, the hurricane turned sharply toward the Southeastern United States. While the move the leading GE scientist, Irving Langmuir, later blamed upon the seeding,[37] subsequent examination of the environment surrounding the storm determined that a large upper-level ridge was in fact responsible for the abrupt turn, which imitated that of a hurricane in 1906.[35][40]

See also

Notes

  1. ^ Starting in 1947 the United States Weather Bureau office in Miami, in conjunction with the military, informally applied the Joint Army/Navy Phonetic Alphabet to Atlantic tropical cyclones; the first storm to be so designated in public advisories was Hurricane Fox in 1950.[2][3]
  2. ^ All damage totals are in 1947 United States dollars unless otherwise noted.
  3. ^ Prior to reanalysis by the National Oceanic and Atmospheric Administration (NOAA) in 2012, HURDAT indicated that the storm intensified once over South Florida, a phenomenon observed in Tropical Storm Fay (2008), which struck the same region.[5]
  4. ^ Note, however, that reconnaissance-derived estimates of wind speed are considered unreliable prior to the mid-1970s, if not more than a decade later.[15]
  5. ^ The Saffir–Simpson scale uses an elevation of 10 m (33 ft) above mean sea level.[23]

References

  1. ^ Multiple sources:
  2. ^ Landsea, Christopher W.; Dorst, Neal M. (June 1, 2021). "Subject: Tropical Cyclone Names: B1) How are tropical cyclones named?". Hurricane FAQ – NOAA/AOML. Hurricane Research Division. Retrieved April 23, 2023.
  3. ^ Norcross 2007, pp. 138–9.
  4. ^ a b c d "Atlantic hurricane best track (HURDAT version 2)" (Database). United States National Hurricane Center. April 5, 2023. Retrieved April 19, 2024. Public Domain This article incorporates text from this source, which is in the public domain.
  5. ^ a b Multiple sources:
  6. ^ Norton 1947a, pp. 8–9.
  7. ^ a b c d Sumner 1947, p. 253.
  8. ^ a b Landsea, Strahan-Sakoskie & Hagen 2012, p. 4452.
  9. ^ a b Landsea, Chris; Anderson, Craig; Bredemeyer, William; et al. Documentation of Atlantic Tropical Cyclones Changes in HURDAT: 1947 Storm 9 (was storm 8) – Revised in 2014. Re-Analysis Project (Report). Miami, Florida: Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division. Retrieved April 19, 2024.
  10. ^ "Latest Storm Bulletin". Miami Herald. Vol. 37, no. 313. Miami. October 12, 1947. p. 1A. Retrieved April 26, 2023 – via Newspapers.com. Free access icon
  11. ^ a b Norton 1947a, p. 9.
  12. ^ a b Norcross 2007, p. 56.
  13. ^ Multiple sources:
  14. ^ Multiple sources:
  15. ^ Landsea, Strahan-Sakoskie & Hagen 2012, pp. 4444–5.
  16. ^ a b c Sumner 1947, p. 254.
  17. ^ Written at Miami. "Caribbean Storm Expected to Hit Cuba by Tonight". Sarasota Herald-Tribune. Vol. 23, no. 7. Sarasota, Florida. Associated Press. October 10, 1947. p. 1. Retrieved August 9, 2023.
  18. ^ Written at Miami. "Severe Storm Sweeping Toward Cuba". The Daily Gleaner. Vol. 113, no. 267. Kingston, Jamaica (published October 11, 1947). Associated Press. October 10, 1947. p. 1. Retrieved August 9, 2023 – via Newspaper Archive. Free access icon
  19. ^ "Winds of 60 MPH Expected In Miami". Miami Daily News. Vol. 52, no. 296 (Evening ed.). Miami. October 11, 1947. p. 1. Retrieved August 21, 2023 – via Newspapers.com. Free access icon
  20. ^ a b c d "Flooded Miami in Hurricane Path". Sarasota Herald-Tribune. Vol. 23, no. 8. Sarasota, Florida. Associated Press. October 12, 1947. p. 1. Retrieved July 29, 2012.
  21. ^ "Endangered Areas Given Little Time To Board Up". Miami Daily News. Vol. 52, no. 297. Miami. October 12, 1947. p. 1. Retrieved August 21, 2023 – via Newspapers.com. Free access icon
  22. ^ a b c d Barnes 1998, p. 175.
  23. ^ Simiu, Vickery & Kareem 2007, p. 1043.
  24. ^ a b c d e Norcross 2007, p. 57.
  25. ^ Kleinberg 2003, p. 220.
  26. ^ Schoner & Molansky 1956, pp. 170–1.
  27. ^ a b c d e f Written at Fort Lauderdale, Florida. "Three 1947 Storms Produced Record Rainfall". Broward News. Miami Herald. Vol. 68, no. 276 (First ed.). Miami. September 2, 1978. p. 2-BR. Retrieved April 26, 2023 – via Newspapers.com. Free access icon
  28. ^ Ling 2005, p. 180.
  29. ^ a b c d e f McIver 1983, pp. 135–7.
  30. ^ a b c d e f g h "The Great South Florida Flood". South Florida Sun-Sentinel. September 9, 1990.
  31. ^ a b USWB 1947, p. 203.
  32. ^ Grazulis 1993, p. 933.
  33. ^ Johnson 1974.
  34. ^ Barnes 1998, p. 177–9.
  35. ^ a b Norcross 2007, pp. 57–8.
  36. ^ Davies 2000, p. 85.
  37. ^ a b Willoughby et al. 1985, p. 505.
  38. ^ GERL 1952, p. 61.
  39. ^ Christopher Landsea (n.d.). "What was Project Stormfury?" (FAQ). Tropical Cyclone FAQ Subject C4. Hurricane Research Division. Retrieved April 22, 2023.
  40. ^ Whipple 1982, p. 151.

Bibliography

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=1947_Florida–Georgia_hurricane&oldid=1178955861"