1970 Atlantic hurricane season

The 1970 Atlantic hurricane season officially began on June 1 and lasted until November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. The season was fairly average, with 14 named storms forming, of which seven were hurricanes. Two of those seven became major hurricanes, which are Category 3 or higher on the Saffir–Simpson scale. Also, this was the first season in which reconnaissance aircraft flew into all four quadrants of a tropical cyclone. though activity began slightly earlier with Hurricane Alma forming on May 17. Although 21 tropical depressions developed, only fourteen of them reached tropical storm intensity. However, this was well-above the 1950–2000 average of 9.6 named storms per season. Seven of these reached hurricane status, slightly above the 1950–2000 average of 5.9. The Atlantic hurricane season officially ended on November 30,

Systems

Hurricane Alma

An area of disturbed weather persisted over the southwestern Caribbean in the middle of May. It gradually organized, and a tropical depression formed on May 17. In response to low wind shear and warm sea surface temperatures, Impact was most severe in Cuba, where flash flooding caused seven fatalities, destroyed several homes, forced the evacuation of 3,000 people in Oriente Province, and forced 16 sugar mills to suspend operations. In other states, impact came mostly in the form of rain, though a tornado near Columbia, South Carolina, unroofed one building.

Tropical Storm Becky

A large disturbance began to detach from the Intertropical Convergence Zone near Panama on July 16. Some houses near Tallahassee were flooded with of water, resulting in the evacuation of 15 households by rowboat. More than 100 cars in the area were also submerged. In nearby Wakulla County, knee-deep waters were reported at the county courthouse in Crawfordville. In Louisiana, abnormally tides caused minor coastal flooding. The strongest sustained wind speeds in Texas were around , while winds gusts were estimated to have reached as high as in Nueces County. Severe damage was reported in Nueces County, with 85% of Celia's total property losses caused in Corpus Christi alone. Approximately 90% of downtown buildings were damaged or destroyed, while about one-third of homes in the city suffered severe impact or were demolished. In Texas, Celia caused 15 deaths and $930 million in damage.

August hurricane

A tropical depression developed off the west coast of Africa on August 7, with organized convection and banding features. A day later, the depression passed south of Cabo Verde as it moved across the tropical Atlantic. On August 10, it intensified into a tropical storm, after the thunderstorms became more concentrated. However, a Hurricane Hunters flight two days later observed a weak system, suggesting the storm weakened back to a tropical depression. While approaching the Lesser Antilles, the depression turned to the northwest and re-intensified back into a tropical storm, with hurricane-force wind gusts north of the center. Late on August 14, the circulation opened into a trough. On August 15, a circulation reformed, and the system became a tropical depression again as it bypassed the eastern Bahamas. A day later, the system re-intensified into a compact tropical storm while turning northward. On August 17, the storm made landfalls along the Outer Banks of North Carolina, first on Atlantic Beach and later at Rodanthe. As the storm accelerated northeastward, it intensified into a hurricane, with peak winds of 80 mph (130 km/h), based on the well-defined eye and a report from a nearby ship. On August 18, the system became extratropical south of Newfoundland, and subsequently it slowed and shifted its track back to the south, only to resume an easterly track on August 21. Late on August 24, the former hurricane dissipated north of the Azores. Minor wind damage was reported in Atlantic Beach and Morehead City, primarily limited to some trees, power lines, roof shingles, television antennas, and signs. From North Carolina to Maryland, lifeguards made dozens of rescues. Four drowning deaths occurred, with two in North Carolina and two in Virginia.

Tropical Storm Dorothy

A tropical wave moved off the western coast of Africa on August 13. Moving westward, a tropical disturbance spawned by the wave led to the formation of a tropical depression beginning east of the Lesser Antilles on August 18. As it moved west-northwestward, it slowly intensified, and was upgraded to Tropical Storm Dorothy several hours later. Around 06:00 UTC on August 20, Dorothy attained its peak intensity with maximum sustained winds of , several hours before striking Martinique. After passing through the Lesser Antilles, Dorothy moved under an upper-level cold-core trough, Banana, sugar cane, and other crops sustained heavy losses. Flooding rains also overspread Dominica and Guadeloupe, but with less severe effects. While the exact death toll of Dorothy is unknown, some sources claim that as many as 51 fatalities occurred. Storm damage amounted to $34 million.

Early September tropical storm

A tropical wave exited the coast of Africa on August 29 and progressed westward, with associated thunderstorms evident on satellite imagery. The system's structure organized, evolving into a tropical depression by September 3. A trough to its north steered the nascent depression northward. Despite the presence of wind shear, the depression intensified as its area of thunderstorms expanded. On September 5, the Hurricane Hunters flew into the system and estimated sustained winds of 45 mph (75 km/h), making it a tropical storm. The continued shear displaced the thunderstorms to the east of the center, as the circulation began moving to the west-southwest. On September 7, the storm weakened back to a tropical depression. On September 11, it passed north of the Lesser Antilles, still as a weak depression. After passing north of Puerto Rico, the depression dissipated on September 13 north of Hispaniola. The remnants continued westward without developing. Ella brought heavy rainfall to portions of northeastern Mexico. Several homes were destroyed and villages along the San Marcos River were inundated by water. One girl died after her house collapsed. Flooding and continuous precipitation prevented the transportation of relief items, including food and medicine, by helicopters. In Texas, tides peaked at above normal, but no coastal flooding damage was reported.

Tropical Storm Felice

On September 12, a tropical depression developed from an upper-level trough just south of Abaco Islands.

In advance of the cyclone, officials advised residents in vulnerable communities to evacuate their homes, and temporary storm shelters were established. However, the effects from Felice were generally light. Beneficial rains fell over parts of southern Florida, while sections of coastal Louisiana experienced minimal gale-force winds and above-normal tides. In Texas, winds gusting to 55 mph (89 km/h) at Galveston—and estimated near 70 mph (110 km/h) elsewhere—caused scattered power outages and minor tree damage, while heavy rainfall totaling over 6 in (150 mm) triggered some street flooding.

Early October hurricane

A tropical wave exited the west coast of Africa September 24, and for several days maintained a general westward track. On September 30, a flight from the Hurricane Hunters observed a well-defined circulation, while ships in the area reported gale-force winds; these observations indicated that a tropical storm had developed. The storm moved west-southwestward, passing St. Lucia and St. Vincent into the Caribbean Sea on October 2. It weakened thereafter, briefly degenerating into a trough before redeveloping into a tropical depression on October 5. It re-intensified into a tropical storm as it meandered south of Hispaniola, eventually hitting the Dominican Republic on October 8 as a tropical depression. It crossed the island into the Atlantic and moved northeastward ahead of an approaching cold front, briefly becoming a tropical storm again on October 10. The storm became extratropical as it integrated with the trough on October 11, moving quickly to the east and east-northeast. Thunderstorms increased on October 14, and a day later, the stalled about halfway between the Azores and Madeira due to a ridge over northern Europe. By that time, the system became integrated with an upper-level low while no longer associated with the front; as a result, it became a subtropical storm. Turning back to the west, the storm re-intensified, becoming a fully tropical hurricane on October 17. A day later, it attained peak winds of 85 mph (135 km/h). The hurricane turned to the north, weakening back to a tropical storm on October 20. A day later, it transitioned into an extratropical cyclone, which was absorbed by another cyclone southeast of Greenland on October 22. it left three deaths and moderate damage on the island. Another death was reported in the United States Virgin Islands. Torrential rainfall in Puerto Rico inflicted heavy damage, with precipitation peaking at in Jayuya, of which fell in a 24‑hour period, far exceeding the peak rainfall amounts during the 1928 and 1899 hurricanes. Most of the damage was inflicted to sugar cane and coffee crops. Additionally, at least 600 houses were destroyed and another 1,000 sustained damage, while about 10,000 people were left homeless. including 15 blocked by landslides, and 11 bridges destroyed. Overall, damage in Puerto Rico totaled $65 million. At least 18 people were killed on the island, As a result of gale-force winds being observed, the system was then designated as Tropical Storm Greta. However, the storm did not strengthen, despite favorable conditions, and as a result, it was described by the National Hurricane Center (NHC) as a "bomb that did not explode".

While approaching the Florida Keys, Greta abruptly weakened to a tropical depression, coinciding with deterioration of the cloud pattern. In addition, Hurricane Hunters reported rising pressures and lower winds. On the evening of September 27, Greta made landfall in Key West, Florida, with sustained winds of . Rainfall was mostly light, though of precipitation was observed in Fort Pierce. It continued to intensify and briefly became a Category 2 hurricane on October 17. The hurricane then accelerated rapidly northeastward, and made landfall on the Avalon Peninsula of Newfoundland as a Category 1 hurricane. Shortly thereafter, the hurricane transitioned into an extratropical cyclone on October 17.

The hurricane produced high winds on Bermuda, canceling classes, interrupting transportation, and closing businesses, though damage was minimal. In addition, light rain fell on the island. Throughout Newfoundland, hurricane-force winds caused damage to structures, mostly in the form of broken windows. Rough seas along the Atlantic coast of the island damaged fishing dories and a fishing ramp. Heavy rainfall was also reported in some areas of the region, reaching nearly 5 in (130 mm) in Quebec. Damage on the Burin Peninsula was in the thousands of Canadian dollars, although the specific figure is unknown. On the French territory of Saint Pierre and Miquelon, several buildings lost their roof due to high winds. This is the same list used in the 1966 season, with the exceptions of Felice and Isabel, which replaced Faith and Inez, respectively. A storm was named Felice for the first time in 1970.

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Alma
Becky
Celia
Dorothy
Ella
Felice
Greta

Retirement

The name Celia was later retired.

Season effects

This is a table of all of the storms that formed in the 1970 Atlantic hurricane season. It includes their name, duration, peak classification and intensities, areas affected, damage, and death totals. Deaths in parentheses are additional and indirect (an example of an indirect death would be a traffic accident), but were still related to that storm. Damage and deaths include totals while the storm was extratropical, a wave, or a low, and all of the damage figures are in 1970 USD.