The 1973 Atlantic hurricane season was a below average tropical cyclone season overall. Of the 14 tropical or subtropical cyclones which developed, 12 became nameable storms, and of those, 5 became hurricanes, with 1 reaching major hurricane status (Category 3 or higher) on the newly implemented Saffir–Simpson hurricane wind scale.
The season officially began on June 1 and ended on November 30. These dates, adopted by convention, historically describe the period in each year when most tropical cyclones form in the North Atlantic. However, the formation of subtropical or tropical cyclones is possible at any time of the year, as demonstrated this season by the formation of multiple pre-season systems, none of which attained storm strength. The first named storm of the year, Hurricane Alice, did not form until July 1.
Two of the season's landfalling storms had severe impacts. In August, Hurricane Brenda struck the eastern coast of the Bay of Campeche, killing 10 people in Campeche, and causing the worst flooding there in decades. Then, early in September, Hurricane Delia hit the northwestern Gulf of Mexico coast, inundating parts of Texas and Louisiana with significant rainfall, which resulted in 5 fatalities and $6 million (1973 USD) in damage. The most intense cyclone of the season was Hurricane Ellen, which reached Category 3 strength during its trek over open water. Also, the season's final named storm, Tropical Storm Gilda, was meteorologically significant in that it became the first documented tropical cyclone on record to transition into a subtropical cyclone after having transitioned to an extratropical cyclone.
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Season summary The first storm of the 1973 hurricane season, forming in late April, developed more than a month before the official start of the season. Several other short-lived, weak depressions formed before and during June; however, none reached storm intensity. The first named storm, Alice, formed on July 1. Tracking generally to the north, Alice also became the first hurricane of the season as well as the first known cyclone to impact Bermuda during July. By the end of July, an unnamed tropical storm formed, which was closely followed by the formation of the season's first subtropical cyclone, given the name Alfa, developing off the east coast of the United States. This storm was short-lived and dissipated on August 2 just offshore southern Maine. The remainder of the first half of August featured no storms. However, later in the month, the season's second hurricane, Brenda, formed in the northwestern Caribbean. Peaking just below Category 2 status on the newly introduced Saffir–Simpson hurricane scale, Brenda made the first recorded landfall in the Mexican State of Campeche.
Later in August, Tropical Storm Christine became the easternmost forming tropical cyclone in the Atlantic basin on record, developing over the western African country of Guinea on August 25. The system traveled for several thousand miles before dissipating in the eastern Caribbean Sea in early September. At the start of the month, Hurricane Delia formed in the Gulf of Mexico, later becoming the first known cyclone to make landfall in the same city twice. After moving inland a second time, Delia eventually dissipated on September 7. As Delia dissipated another depression formed in the same region, eventually making landfall in the same city as Delia, Freeport, Texas. Another unnamed tropical storm formed several days later. On September 13, the strongest storm of the season, Ellen, formed over the eastern Atlantic. After tracking northwest for several days, Ellen eventually attained hurricane status as it turned westward. Several days later, the hurricane turned northeast due to an approaching frontal system. Shortly before becoming extratropical, Ellen reached major hurricane intensity at a record northerly latitude.
In late September, a brief subtropical depression affected northern Florida before dissipating. After a week of inactivity, two more storms formed: an unnamed tropical storm, and the second subtropical cyclone of the year. The latter of the two, named Bravo, gradually intensified, becoming fully tropical, at which time it was renamed Fran, a few days later. Upon being renamed, Fran had intensified into a hurricane and maintained this intensity for several days before dissipating east of the Azores on October 12. A few days after Fran dissipated, the final named storm of the year formed in the central Caribbean Sea. A slow moving system, Gilda gradually intensified just below hurricane-intensity before striking Cuba and moving over the Bahamas. A few days after passing through the islands, Gilda became the first storm on record to transition from a tropical cyclone into a subtropical cyclone. A large storm, Gilda eventually became extratropical near Atlantic Canada and dissipated later that month. Around the time Gilda was dissipating, a weak depression briefly existed near the Azores. The final storm of the year was a strong depression in the southern Caribbean Sea. This system was active for less than two days but may have briefly attained tropical storm intensity as it made landfall in southern Nicaragua.
Systems
Hurricane Alice
The first named storm formed out of the interaction between tropical wave and a mid-level tropospheric trough northeast of the Bahamas in late-June. A well-defined circulation became apparent by June 30 and satellite images depicted cyclonic banding features. On the following day, the system intensified into a tropical depression. On July 2 it became a tropical storm as reconnaissance aircraft recorded gale-force winds. An area of high pressure to the east of Alice steered the storm generally to the north. Decreasing wind shear allowed the storm to become increasingly organized and an evident eye developed by July 3. By this time, reconnaissance had determined that the storm had intensified into a hurricane, but a 2026 reanalysis found that Alice remained a strong tropical storm until a day later.
On July 4, the storm reached its peak intensity with winds of and a barometric pressure of 984 mbar (hPa; ), as the eastern portion of the eyewall brushed Bermuda. Alice was then a compact storm, with a smaller-than-usual eye diameter and elevated ambient pressures. At the time, Alice was regarded as the first July tropical cyclone to closely bypass Bermuda. After passing the island, Alice began to accelerate in response to a mid-level trough over the eastern United States and weakened. By July 6, winds head decreased below hurricane intensity as the storm neared Atlantic Canada. Later that day, Alice made landfall in western Newfoundland with winds of 60 mph (95 km/h), before transitioning into an extratropical cyclone.
During its passage of Bermuda, Alice produced sustained winds up to 75 mph (120 km/h) and gusts to 87 mph (140 km/h). The winds blew down a few trees and powerlines. The heavy rainfall, peaking at , ended a three-month drought in Bermuda. Although Alice tracked through Atlantic Canada, no impact was recorded.
Unnamed July tropical storm
On July 23, satellite and station data confirmed a closed low-pressure area over the Gulf of Honduras. The system quickly became a tropical storm, as shown by several reports of gales. After peaking with winds of 45 mph (75 km/h), the storm struck southern British Honduras a day later with the same winds. By July 25 the cyclone ended over southeastern Mexico.
Subtropical Storm Alfa
During late July, an upper-level low, with a non-tropical cold core, formed near Cape Hatteras, North Carolina and tracked southward. Gradually, the circulation lowered to the surface and developed subtropical characteristics. On July 31, the system attained gale-force winds off the Mid-Atlantic coast and was named Alfa, the first name from the list of subtropical storm names for the 1973 season. Tracking north-northeast, the system intensified very little as it paralleled the coastline. By August 1, the system weakened below subtropical storm intensity as it neared New England. The following day, Alfa dissipated just off the southern coast of Maine. The only effects from Alfa was light to moderate rainfall in New England, peaking at in Turners Falls, Massachusetts. Most of southern Maine recorded around , with a maximum of in Saco.
Hurricane Brenda
Hurricane Brenda originated from a tropical wave that moved off the western coast of Africa on August 9; however, the initial wave quickly weakened upon entering the Atlantic Ocean. By August 13, the wave began to regenerate as it passed through the Lesser Antilles. Several days later, convection associated with the system consolidated into a central, organized mass and on August 18, the system had become sufficiently organized to be declared a tropical depression while situated near the Yucatán Channel. Early the next day, the depression strengthened into Tropical Storm Brenda as it made landfall in the northern portion of the Yucatán Peninsula. After moving inland, a strong ridge of high pressure over Texas forced the storm to take an unusual track, eventually leading it to enter the Bay of Campeche on August 20.
Once back over water, Brenda began to intensify, attaining hurricane status late on August 20. The next day, a well-defined eye had developed and the storm attained its peak intensity as a high-end Category 1 hurricane with winds of 90 mph (150 km/h) and a minimum pressure of 977 mbar (hPa; ). It is possible that Brenda reached Category 2 intensity, but the data is inconclusive to support such. The storm made landfall later that day near Ciudad del Carmen, Mexico at this intensity, becoming the first hurricane on record to strike the region. After moving inland, Brenda rapidly weakened to a depression by the morning of August 22 and dissipated later that day.
Already suffering from severe flooding that killed at least 18 people and left 200,000 homeless, Hurricane Brenda worsened the situation with torrential rainfall and additional flooding. The storm killed at least 10 people in the country. Following the damage wrought by Brenda, a large earthquake struck the region, hampering relief efforts and collapsing numerous structures. Winds on land gusted up to 112 mph (180 km/h), leading to severe wind damage. Two of the fatalities occurred in Campeche after 80% of the city was flooded. This was considered the worst flooding in the city in over 25 years. An estimated 2,000 people were left homeless as a direct result of Brenda throughout Mexico. Offshore, a freighter with 25 crewman became trapped in the storm after its engines failed. They were safely rescued several days later once the storm had dissipated.
Tropical Storm Christine
Tropical Storm Christine originated from a tropical wave over Africa in mid-August. As it neared the Atlantic Ocean, the wave organized into a tropical depression shortly after emerging from Guinea at 16.4°W. It steadily tracked west across the Atlantic, and attained tropical storm intensity on August 28. Despite the lack of aircraft reconnaissance in the region, the intensity was determined by wind readings from a German cargo ship that passed through the storm. On August 30, the first reconnaissance mission into the storm found tropical storm-force winds and the first advisory was issued that day, immediately declaring the system as Tropical Storm Christine. Three days later, Christine attained its peak intensity, with winds of and a minimum pressure of 999 mbar (hPa; ). Shortly thereafter, increasing wind shear caused the storm to weaken as it neared the Leeward Islands. As it passed over Antigua on September 3, Christine weakened to a tropical depression and eventually dissipated near the Dominican Republic later that day.