1956 Atlantic hurricane season

The 1956 Atlantic hurricane season featured a decent number of tropical cyclones, although most tropical storms and hurricanes affected land. There were twelve tropical storms, a third of which became hurricanes. One of the hurricanes strengthened to the equivalent of a major hurricane, which is a Category 3 or greater on the Saffir–Simpson scale. The strongest hurricane of the season was Betsy, which was also the most damaging storm of the season: it destroyed 15,000 houses and left $40 million in damage in Puerto Rico. Betsy was also the deadliest of the season, having killed 18 people in the French West Indies, two from a shipwreck in the Caribbean Sea, and 16 in Puerto Rico. Tropical Storm Dora struck Mexico in September and killed 27 people.

The season officially started on June 15, although an unnamed storm developed about a week prior over the western North Atlantic Ocean. A later storm that formed over the Gulf of Mexico on June 12 alleviated drought conditions in the south-central United States. Hurricane Anna developed in late July and hit Mexico. Tropical storms Carla and Ethel both formed near the Bahamas and moved northeastward until dissipating. The only hurricane that hit the contiguous United States was Hurricane Flossy. One of the final storms of the year, Greta, was an unusually large hurricane that produced high waves from Florida to the Lesser Antilles. It developed in the western Caribbean and moved across much of the southeastern United States, causing $24.8 million in damage and 15 deaths.

Season summary

The season officially began on June 15, the date that the Weather Bureau office in Miami, Florida, under the direction of Gordon Dunn, began daily monitoring of all tropical disturbances and cyclones across the northern Atlantic Ocean. The agency had access to the hurricane hunters, a fleet of aircraft that obtain data by flying into storms. The Weather Bureau, in collaboration with other agencies, began a five–year project in 1956 to obtain and analyze data on the structure of hurricanes. The season officially ended on November 15.

There were a total of twelve tropical storms during the season, five of which were unnamed. In all, four storms strengthened into hurricanes. Compared to the average activity from the previous two decades, the season's activity was below normal despite average sea surface temperatures and a normal number of tropical waves. Instead, the inactivity was the result of the subtropical ridge being located further south than normal, which decreased the atmospheric instability across much of the basin. Such a pattern was different from the more active 1954 and 1955 seasons. Several tropical depressions formed that did not attain tropical storm status, many of which formed beneath an unfavorable upper-level trough.

The season's activity was reflected with a cumulative accumulated cyclone energy (ACE) rating of 54, which is categorized as being "below normal". ACE is, broadly speaking, a measure of the power of the hurricane multiplied by the length of time it existed, so storms that last a long time, as well as particularly strong hurricanes, have high ACEs. ACE is only calculated for full advisories on tropical systems at or exceeding or tropical storm strength. Thus, tropical depressions are excluded from the total.

Systems

Early June tropical storm

A dissipating cold front off the southeastern United States spawned a low-pressure area on June 6. On the next day, the system organized into a tropical storm off the coast of North Carolina. The storm moved southward and reached peak winds of , based on reports from ships. During its duration, the storm failed to develop an inner core, affected by cool, dry air to the northwest. The structure was likely akin to a subtropical storm, based on its formation beneath an upper-level trough. On June 8, the storm accelerated to the northeast ahead of an approaching cold front, weakening to a tropical depression the next day, and becoming an extratropical cyclone within the front on June 10. The system dissipated later that day as a larger storm developed within the front.

Mid-June tropical storm

During the second week of June, a tropical wave traversing the Yucatán Peninsula commenced interacting with a trough extending from the Gulf of Mexico to the western Atlantic Ocean, which generated a disturbance over the Bay of Campeche, that spawned a tropical depression on June 12. The newly developed tropical cyclone tracked northward, quickly intensifying into a tropical storm. It attained peak winds of on June 13, although it never developed a well-defined circulation. In addition, it had characteristics of both a tropical and extratropical cyclone, with cooler air aloft. Late on June 13, the storm made landfall near Cocodrie, Louisiana, and its lowest pressure of was measured over land, suggesting it did not weaken substantially after landfall. After moving inland, it dissipated on June 15 over Arkansas.

As the storm moved ashore, it did not develop rainbands, unlike other tropical cyclones. The heaviest rainfall occurred in a region east of where it moved ashore. Precipitation fell across the entire United States gulf coast, and the highest rainfall total was in Golden Meadow, Louisiana. The rains were beneficial to farmers, due to drought conditions persisting in the region. The storm produced higher than normal tides, peaking at in Biloxi, Mississippi; this was the highest since the 1947 Fort Lauderdale hurricane. The tides left damage to the Freeport Sulphur Company, as well as to boats, beaches, and piers. Three people died after their boat capsized, and there was another death after a driver skidded off the Lake Pontchartrain Causeway. A barge in the lake became disabled due to the storm and caused light damage to the causeway. Sustained winds during the storm's passage peaked at near Grand Isle, Louisiana, and a boat reported a gust of near Pilottown, Louisiana. Damage was estimated at $50,000.

Hurricane Anna

A westward-moving tropical wave traversed the Lesser Antilles on July 20. It moved across the Caribbean, and its thunderstorms increased on July 23 while passing south of Cuba and beneath a high-pressure area. There is evidence that it could have developed a circulation on July 24 before it struck the Yucatán Peninsula. It is confirmed to have developed into a tropical depression on July 25 in the Bay of Campeche. As it continued west-northwestward, it rapidly intensified into Tropical Storm Anna, and before moving ashore in Mexico near Ozuluama, Veracruz, on July 26 it attained hurricane status. Peak winds reached , although Anna rapidly dissipated on July 27 as it moved further inland. The high winds wrecked several homes in poor regions of Tampico, Tamaulipas, while rainfall of resulted in flooding. The high winds severed telegraph lines from Tampico to San Luis Potosí. The same area was affected by several hurricanes in the previous year. Damage totaled around $50,000, and there were no deaths.

Hurricane Betsy

A tropical wave moved off the coast of Africa on August 4. It developed into Tropical Storm Betsy developed on August 9 to the east of the Lesser Antilles. It rapidly developed into a hurricane before striking Guadeloupe with a minimum central pressure of . There, Betsy heavily damaged 1,000 houses and left severe crop destruction, and led to 18 deaths. As Betsy continued into the northeastern Caribbean, it capsized a ship, killing its crew of two. On August 12, a slightly weakened Betsy struck southeastern Puerto Rico near Maunabo with winds of and quickly crossed the island. Damage was heaviest where it moved ashore and in the territory's central portion. 15,023 houses were destroyed by Betsy, and multiple locations reported heavy crop damage, including Camuy, which reported a complete loss of the corn crop.

After exiting Puerto Rico, Betsy strengthened steadily as it headed generally northwestward, becoming a major hurricane on August 13 while centered north of the Turks and Caicos Islands. It attained peak winds of the next day to the east of the Bahamas. Betsy later turned northeastward, attaining its lowest central pressure of on August 17. It later became extratropical early on August 18. The remnants dissipated two days later to the north of the Azores. Hurricane Betsy was the first hurricane to be observed from the San Juan radar, and also resulted in the first hurricane warning on the island that was released on television. The hurricane left $40 million in damage and 16 deaths, which prompted the declaration of a federal disaster area. Locally the hurricane was known as the Santa Clara Hurricane.

Tropical Storm Carla

The origins of Tropical Storm Carla were from a tropical wave that spawned a depression near the Bahamas on September 7. It moved generally to the north, intensifying to a tropical storm the following day. An upper-level low located to the northeast of Carla produced hostile conditions that prevented significant strengthening, and Carla had a structure which resembled a subtropical storm. An approaching cold front turned the storm to the northeast, and despite the unfavorable atmosphere, Carla intensified, reaching peak winds of 60 mph (95 km/h) late on September 9. The interaction between the storm and a high-pressure system over the Great Lakes yielded a strong pressure gradient that produced gale-force winds over New England. After Carla passed to the north of Bermuda, it became extratropical on September 10, according to HURDAT—the official hurricane database—and the annual report in the Monthly Weather Review. As a post-tropical cyclone, ex-Carla strengthened to before weakening and dissipating by September 16.

Tropical Storm Dora

On September 10, a tropical depression developed over the Bay of Campeche. Later that day, hurricane hunters observed winds of tropical storm force, indicating that the depression had become Tropical Storm Dora, with winds of about . Dora moved generally westward due to a ridge to its north. A reconnaissance flight on September 11 estimated hurricane-force winds, but reanalysis assessed these as being unrepresentative of Dora's true strength. Early on September 12, Dora peaked at shortly before striking land near Tuxpan with a minimum central pressure of . It quickly dissipated early the next day, although the storm produced heavy rains across the region. The deluge caused a landslide as well as flooding, including along a river near San Andrés Tuxtla. In Puebla, there were 13 deaths and 20 injuries after a bus crashed into a washed out portion of the highway from Tuxpan to Mexico City. Overall, Dora caused 27 deaths in the country, but minor damage.

Tropical Storm Ethel

On September 11, a tropical depression developed along the southern end of a quasi-stationary cold front over Grand Exuma Island in the Bahamas. It moved to the northeast and encountered cold air from the north. This resulted in significant instability that allowed in quick strengthening. A hurricane hunters flight on September 12 reported winds of in the storm's northeast quadrant; as a result, the depression was upgraded to Tropical Storm Ethel. The flight observed a well-developed eye in diameter, although they only observed hurricane-force winds in one quadrant. Reassessment, however, discounted the observations of hurricane-force winds from the aircraft as being unrepresentative of Ethel's strength, and analyzed that Ethel peaked at late on September 12, with the lowest pressure reported being . Shortly after reaching peak intensity, Ethel began weakening and dissipated on September 14 to the southwest of Bermuda.

Hurricane Flossy