The 1972 Atlantic hurricane season was a significantly below average season. Although it featured 12 tropical or subtropical storms, only two strengthened into hurricanes and neither exceeded Category 1 intensity (only 2013 has matched such in the reconnaissance era). It officially began on June 1, 1972, and lasted until November 30, 1972. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. The first storm, Subtropical Storm Alpha, developed on May 23 off the Southeast United States and struck Florida, causing minor damage and two fatalities.
The most significant storm of the season was Hurricane Agnes, which at the time was the costliest United States hurricane, until Frederic in 1979. After brushing the western tip of Cuba, the hurricane made landfall on the Florida Panhandle. It caused at least $2.1 billion (1972 USD) in damage and 131 fatalities, mostly from inland flooding in Pennsylvania and New York. The strongest hurricane of the season was Betty, which reached peak winds of 90 mph (150 km/h) while west of the Azores. Tropical Storm Carrie passed just offshore of Massachusetts, causing heavy rainfall and resulting in four fatalities, but leaving only $1.78 million in damage. The remaining tropical systems caused no significant effects on land.
Due to a strong El Niño only two systems strengthened into hurricanes, none of which intensified into major hurricanes. This was the first season to name subtropical storms in real time, and did so using the Phonetic Alphabet. Collectively, the storms of the 1972 Atlantic hurricane season resulted in 137 deaths and over $2.1 billion in damage.
Season summary
The Atlantic hurricane season officially began on June 1, 1972, although Subtropical Storm Alpha formed on May 23. A total of 17 tropical cyclones developed, with 12 strengthening to nameable storms, above the 1950-2000 average of 9.6 named storms per season.} Of the twelve tropical or subtropical storms, two of them strengthened into hurricanes, tying the record (with 1982 and 2013) for the lowest number in the satellite era. Neither hurricane became major hurricanes, which is Category 3 or greater on the Saffir–Simpson hurricane wind scale, and neither reached Category 2. Overall, the season was inactive, despite having a similar number of tropical waves as the previous season. The lack of activity was attributed to an El Niño – which causes below normal sea surface temperatures over the eastern Atlantic – and strong vertical wind shear. Collectively, the storms of the season caused at least 137 fatalities and more than $2.1 billion in damage. The last storm of the season, Subtropical Storm Delta, became extratropical on November 7, about 23 days before the official end of hurricane season on November 30.
Tropical cyclogenesis first occurred in the month of May, with the development of Subtropical Storm Alpha. The month of June featured two tropical cyclones, including Hurricane Agnes and a tropical depression. Two more systems formed in July, a subtropical storm and a tropical storm. August featured Hurricane Betty, Tropical Storm Carrie, and two tropical depressions. September featured slightly more cyclogenesis, with two unnamed tropical storms, Hurricane Dawn, Subtropical Storm Charlie, and a tropical depression. An additional two tropical depressions formed in October. Subtropical Storm Delta was the sole system in November, lasting from November 1 to November 7.
The season's activity was reflected with an Accumulated Cyclone Energy (ACE) rating of 36, the lowest value since 1962. Broadly speaking, ACE is a measure of the power of a tropical or subtropical storm multiplied by the length of time it existed. Therefore, a storm with a longer duration, such as Betty, will have high values of ACE. It is only calculated for full advisories on specific tropical and subtropical systems reaching or exceeding wind speeds of 39 mph (63 km/h). Accordingly, tropical depressions are not included here. After the storm has dissipated, typically after the end of the season, the NHC reexamines the data, and produces a final report on each storm. These revisions can lead to a revised ACE total either upward or downward compared to the operational value.
Systems
Subtropical Storm Alpha
The origins of Alpha were from a surface low northeast of Florida, associated with the larger-scale, cold core upper low. Late on May 23, it organized into a subtropical depression to the east of the Georgia/South Carolina border. A developing ridge blocked its northeast motion, turning the depression to the southeast. On May 25, a small, intense low-level center organized rapidly. By the next day, it attained gale-force winds and was moving southwestward. At 1600 UTC on May 26, the National Hurricane Center initiated advisories on Subtropical Cyclone Alpha, when the storm was about 225 mi (360 km) to the south of Cape Hatteras. Around that time, it reached its peak winds of 70 mph (110 km/h). Subtropical Storm Alpha was initially well-defined as it moved southwestward. The very small center was located along the eastern edge of the convection, while low-level cloud bands formed east of the center. The winds decreased steadily as it turned more westward on May 27. The National Hurricane Center initially thought the center might not have been at the surface, and the agency indicated low forecasting confidence, as they could not determine a circulation center. The difficulty arose from the large, sprawling nature of the storm, and by later on May 27 a new center formed, as confirmed by radar imagery and the Hurricane Hunters. That night, the extremely small center made landfall just south of Savannah, Georgia, affecting a very small area with winds of 65 mph (100 km/h) and a minimum pressure of 991 hPa (29.26 inHg). Around the time of landfall, Alpha developed a warm core, indicating some tropical characteristics. The storm weakened quickly over land, although it did not dissipate until two days later over the northeast Gulf of Mexico.
The interaction between Alpha and the high pressure system to its northeast caused cooler temperatures and gusty winds from Delaware southward. Wave heights reached up to 20 feet (6.1 m) along the Virginia capes. The storm dropped rainfall along the coast of North Carolina and Virginia, with a maximum of 6.97 inches (177 mm) reported in Ocracoke, North Carolina. While moving slowly off the North Carolina coast, Alpha caused heavy beach erosion, destroyed one house, and threatened the foundation of several other homes in the Outer Banks. Damage totaled over $50,000 (1972 USD). While the storm was traveling over the western Atlantic Ocean, the storm produced a large area of rough seas, which was considered the greatest threat from the storm. In northeastern Florida, police officers were stationed to ensure people did not swim in the dangerous seas. The high waves also halted work to deepen a harbor at the Mayport Naval Station. Two people drowned after the storm dissipated, when surf was still turbulent. Tides along the Georgia coast reached 2 to 3 feet (0.61 to 0.91 m) above normal, which caused some flooding and beach erosion. Wind gusts reached 58 mph (93 km/h) on Saint Simons Island. The winds knocked down trees and power lines, leaving some people without power in eastern Georgia. Damage was minor but widespread in the state, estimated at over $50,000 (1972 USD). Moderate rains spread in coastal areas from South Carolina through southern Florida.
Hurricane Agnes
A polar front and an upper trough over the Yucatán Peninsula spawned a tropical depression on June 14. The storm emerged into the western Caribbean Sea on June 15, and by the following day, it strengthened into Tropical Storm Agnes. The storm curved northward and brushed western Cuba on June 17. Agnes continued to intensify, and on June 18, it was upgraded to a hurricane. Minimal fluctuations in intensity occurred before the storm made landfall near Panama City, Florida, on June 19, with 75 mph (120 km/h) winds. After moving inland, Agnes rapidly weakened and was only a tropical depression when it entered Georgia. Thereafter, weakening slowed as the storm crossed over Georgia and into South Carolina. However, while over eastern North Carolina on June 21, Agnes re-strengthened into a tropical storm, as a result of baroclinic activity. It became post-tropical shortly thereafter, but continued to strengthen. Early the following day, the storm emerged into the Atlantic Ocean before re-curving northwestward and making landfall near New York City. Agnes quickly merged with a non-tropical low pressure system on June 23.
Heavy rainfall occurred in western Cuba, causing flooding that destroyed 97 houses, isolated a few cities, and flatted crops in low-lying areas. The storm left seven fatalities. Agnes caused a significant tornado outbreak, with at least 26 confirmed twisters, 24 of them in Florida and the other two in Georgia. The tornadoes alone resulted in over $4.5 million in damage and six fatalities. At least 2,082 structures in Florida suffered either major damage or were destroyed. About 1,355 other dwellings experienced minor losses. Though Agnes made landfall as a hurricane, no hurricane-force winds were reported. Abnormally high tides resulted in extensive damage, especially between Apalachicola and Cedar Key. The storm left nine deaths and approximately $40 million in damage in Florida. Generally minor effects were also recorded in the states of Alabama, Delaware, Georgia, Ohio, South Carolina, and Tennessee, as well as the New England region. However, one fatality was reported in Delaware and three were recorded in Georgia.
The most significant effects, by far, occurred in Pennsylvania, mostly due to severe flooding. Precipitation peaked at 18 in (460 mm) in Schuylkill County, causing several creeks and rivers crest at record height, including the Delaware, Juniata, Lackawanna, Susquehanna, and West Branch Susquehanna rivers. More than 100,000 people were forced to leave their homes due to flooding. In the state of Pennsylvania, more than 3,000 businesses and 68,000 homes were destroyed, leaving at least 220,000 people homeless. Agnes remains one of the worst natural disasters in Pennsylvania. New York also suffered severe damage. Similarly, rivers in the state crested high, including the Allegheny, Chemung, Genesee, Susquehanna, and Tioga rivers. Corning, Elmira, and Olean, as well as many other Southern Tier towns, were severely flooded. Throughout New York, 32,832 homes were damaged and 628 others were damaged. A total of 1,547 small businesses were extensively damaged or demolished. In Canada, a mobile home was toppled, killing two people. Overall, Agnes caused 131 fatalities and over $2.1 billion in damage.
Unnamed June tropical storm
As Agnes was moving over the southeastern United States, a subtropical storm formed approximately 510 mi (820 km) southwest of Bermuda on June 18. It moved northeastward and headed toward the island. After becoming fully tropical, the system dissipated on June 21.
Unnamed July subtropical storm
A subtropical depression developed offshore North Florida on July 11. Moving generally northward, the system made landfall as a subtropical storm near Cape Fear in North Carolina on July 12. It dissipated over Maryland about two days later. Generally light rainfall was reported in several states, though 8 in (200 mm) of precipitation was recorded on Cedar Island, North Carolina.
Unnamed July tropical storm
A tropical depression originated about 570 mi (920 km) west-southwest of Flores Island in the Azores on July 18. It trekked slowly until July 19, at which time the system curved northeastward. The following day, the system became a tropical storm. It dissipated about 450 mi (720 km) northeast of Flores Island on July 23.
Hurricane Betty (Bravo)
An area of disturbed weather appeared on satellite imagery while forming within an old frontal zone on August 21. At 1200 UTC on the following day, a subtropical depression developed about 290 mi (470 km) north-northeast of Bermuda. The system strengthened slowly as it headed east-northeastward or eastward and by August 24, it became Subtropical Storm Bravo. During the next 24 hours, minimal intensification occurred. However, a deepening high-level trough and a building ridge enhanced outflow and deep convection on August 25. Additionally, reconnaissance aircraft flights began indicating a transition to a warm-core. Unfavorable northwesterly winds briefly halted further development, though by late on August 26, Bravo resumed acquiring tropical characteristics after another deepening trough accelerated the storm eastward.