The 1986 Atlantic hurricane season was a very inactive season that produced 10 depressions, 6 named storms, 4 hurricanes, and no major hurricanes. The season officially began on June 1, 1986, and lasted until November 30, 1986. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. During the 1986 season, the first subtropical depression formed in the first week of June, while the last tropical cyclone dissipated at the end of the third week of November. The 1986 season had lower than average activity because of an ongoing El Niño, and was the least active season in the North Atlantic since the 1983 Atlantic hurricane season. This was also the first season since 1972 to have no major hurricanes.
The season started on June 5 when Subtropical Depression One formed near the Bahamas, which would later gain tropical characteristics and become the first tropical storm of the season; Tropical Storm Andrew. On June 9, Andrew would later be absorbed by a larger low pressure system. On June 23, the season's first hurricane formed; Bonnie, although it attained hurricane status on June 25, just two days after Bonnie's formation. Two more tropical depressions followed suit later in the season. On August 13, the season's fifth tropical depression formed and would later become Hurricane Charley four days later. After Charley dissipated, two more tropical depressions formed on August 31 and September 1. Both dissipated on September 4. On September 7, Tropical Storm Danielle formed and would dissipate on September 10. Just after Danielle dissipated, Hurricane Earl formed and would later become the strongest system of the 1986 Atlantic hurricane season, peaking as a 105 mph Category 2 hurricane and 979 mbars in lowest pressure. No tropical cyclones formed during the months of October and the first half of November. That is, until Hurricane Frances became the latest sixth named storm on record since tropical cyclones were first named in 1950. The season came to a close on November 21, which was when Frances dissipated.
Seasonal forecasts
Forecasts of hurricane activity are issued before each hurricane season by noted hurricane experts such as Dr. William M. Gray and his associates at Colorado State University (CSU). A normal season, as defined by the National Oceanic and Atmospheric Administration (NOAA) in the period from 1981 to 2010, has approximately twelve named storms, with six of those reaching hurricane status. About three hurricanes strengthen into major hurricanes, which are tropical cyclones that reach at least Category 3 intensity on the Saffir–Simpson scale. In early 1986, the Weather Research Center (WRC) predicted eleven tropical storms and five hurricanes.
CSU issued forecasts on May 29 and July 28 indicating within both forecasts the anticipation of a below normal hurricane season, the former citing the absence of an El Niño event and eastward winds associated with the quasi-biennial oscillation. In May, a total of 8 named storms were expected, with four hurricanes expected, 15 days with hurricanes, and a total of 35 days with a tropical storm active in the northern Atlantic Ocean. In July, the numbers were dropped to a total of 7 named storms, 4 hurricanes, 10 hurricane days, and 25 days with a named tropical storm, which almost perfectly verified. CSU lowered their numbers from the previous prediction after data indicated high sea-level pressure anomalies over the Caribbean Sea and Gulf of Mexico and westward-oriented zonal wind anomalies, both of which favored less tropical cyclone activity.
Season summary
The season's activity was reflected with a cumulative accumulated cyclone energy (ACE) rating of 36, which is classified as "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 34 knots (39 mph; 63 km/h) or tropical storm strength. Subtropical cyclones are excluded from the total.
Systems
Tropical Storm Andrew
In early June, a large area of disturbed weather persisted over the Greater Antilles, bringing heavy rains to the islands. The area moved northward, developing a circulation over the Bahamas. Strong upper-level winds caused the structure to resemble a subtropical cyclone, and as a result, the system was classified as a subtropical depression on June 5. The depression moved to the northwest and transitioned into a tropical storm on June 6; it was named Andrew about 260 mi (420 km) southeast of Charleston, South Carolina. The storm approached the South Carolina coast within 115 mi (185 km) before recurving to the northeast on June 7. The storm passed within 70 mi (115 km) of Cape Hatteras while near its peak intensity with winds of 50 mph (85 km/h) and a minimum pressure of 999 mbar (29.5 inHg). Andrew accelerated northeastward and briefly crossed into the forecasting territory of Environment Canada. before being absorbed by a low pressure system over Canada on June 8.
While active, Andrew posed a threat to the Carolinas. Gale warnings were posted from Cape Lookout, North Carolina, to south of Virginia Beach, Virginia, on June 7. Waves reached heights of 12-foot (3.7 m) off the coast of the Carolinas, which killed a person on Ocracoke Island. Three companions were also swept out, all of whom made it back to shore. At Wrightsville Beach and Carolina Beach, at least 40 swimmers were caught in the currents, four of whom were hospitalized. The precursor to the storm produced heavy rainfall across Jamaica that caused a deadly flood event.
Hurricane Bonnie
During late June, a frontal trough drifted into the northeastern Gulf of Mexico, and by June 22, a surface circulation formed. Tracking west-northwestward, it developed into Tropical Depression Two on June 23 while located about 330 mi (530 km) south of Pensacola, Florida. The next day, it attained tropical storm status, and with continued favorable conditions attained hurricane status on June 25 to the south of Louisiana. Peaking with winds of 85 mph (140 km/h) early on June 26, Bonnie turned to the northwest and made landfall near Sea Rim State Park in Texas, with a barometric pressure of 990 mbar (29 inHg). The storm quickly weakened over land as it turned to the north and northeast, and on June 28, Bonnie was absorbed by an approaching frontal zone in southeastern Missouri.
Prior to moving ashore, 22,000 people were evacuated. Upon making landfall, Bonnie produced a storm surge peaking at 5.2 ft (1.6 m) at Sabine Pass. Rainfall from the storm peaked at 13 in (330 mm) in Ace, Texas, which caused some street flooding and destroyed a small dam in Liberty County. The hurricane also spawned eleven tornadoes, which, in combination with moderate winds, destroyed about 25 residences in southwestern Louisiana. Farther north, flooding damaged 507 homes and 20 businesses in Bossier, Caddo, and northern DeSoto parishes combined. Three deaths occurred in the Port Arthur, Texas, area; two from separate car accidents and another after a partially paralyzed woman died in a house fire. Bonnie caused damage totaling approximately $42 million.
Tropical Depression Three
The third tropical depression of the season was detected early on July 23 in the open waters of the Atlantic, southeast of Bermuda. While about 180 mi (290 km) north of the island on July 27, the storm was moving northward at 15 mph (24 km/h) while winds were about 30 mph (50 km/h), after maintaining sustained winds of 35 mph (55 km/h) on the previous two days. Later that afternoon, aircraft reconnaissance found no well-defined circulation and the storm's status was reduced from a depression. The depression never threatened any land areas.
Unnumbered tropical depression
A tropical disturbance was detected on August 4 in the northwestern Gulf of Mexico along the lower Texas coast. The low-pressure system moved slowly toward land, limiting the system's development. On August 5, the system became organized enough to be considered a tropical depression. The storm moved inland overnight, dumping several inches of rain over South Texas and causing street flooding in Brownsville and nearby South Padre Island. The system caused rainfall up to 4.45 in (113 mm) in some areas but had no major problems attributed to it. This storm was not carried as a depression operationally, and thus has no assigned number.
Hurricane Charley
A trough of low pressure persisted over Florida on August 11. After organizing and merging with a decaying frontal trough, a subtropical depression formed on August 13 near the mouth of the Aucilla River. The weak storm initially moved northeastward and then eastward, emerging into the Atlantic near Hilton Head Island, South Carolina, on August 15. That day, the system transitioned into a tropical cyclone and intensified into a tropical storm off the coast of South Carolina. Charley attained hurricane status on August 17, just before making landfall in North Carolina near Cape Lookout. After reemerging into the Atlantic near the North Carolina–Virginia state line early on August 18, Charley peaked with winds of 80 mph (130 km/h) and a minimum pressure of 987 mbar (29.1 inHg). It then gradually weakened over the north Atlantic before transitioning into an extratropical cyclone about 225 mi (360 km) southeast of Sable Island, Nova Scotia, though its remnants remained identifiable for over a week until after crossing the British Isles and dissipating on August 30.
The storm brought light to moderate rains along its path through the southeastern United States, alleviating drought conditions in Georgia and South Carolina. In North Carolina, tidal flooding and downed trees were the primary impact. The storm brought high winds to southeastern Virginia, where 110,000 people lost power. Minor damage extended along the Atlantic coastline northward through Massachusetts. Charley caused about $15 million in damage in the United States and five deaths, all due to indirect causes. One person drowned in Newfoundland. The extratropical remnants of Charley brought heavy rainfall and strong winds to the British Isles, causing at least 11 deaths. In Ireland, the rainfall set records for 24‑hour totals, including an accumulation of more than 7.8 in (200 mm), which remains the highest daily precipitation total in the country. Consequently, widespread flooding occurred, with two rivers overflowing their banks. In the Dublin area, 451 buildings were flooded, some up to a depth of 8 ft (2.4 m). In the United Kingdom, the storm downed trees and power lines, as well as flooded rivers.
Tropical Depression Five
This tropical depression formed in the eastern tropical Atlantic Ocean on August 31. The depression moved west-northwest, then northwest away from the Caribbean Sea without further development before dissipating east-southeast of Bermuda on September 4.
Tropical Depression Six
A tropical wave crossed the Caribbean sea, moving into a favorable upper environment in the western Caribbean sea on August 31. The system formed into a weak tropical depression before crossing the Yucatán peninsula, becoming better organized as it moved into the south-central and western Gulf of Mexico between September 1 and 3. The system moved ashore east-central Mexico before quickly dissipating as a tropical cyclone on September 4. Satellite imagery revealed that its residual cloud pattern persisted over Mexico for an additional couple of days before degenerating. Heavy rainfall fell primarily north of its track, with the maximum across northeast Mexico falling at El Barranco/Altamira, where a total of 9.33 inches (237 mm) was measured.
Tropical Storm Danielle
Around September 1, a tropical wave exited western Africa and proceeded westward. A tropical depression developed along the tropical wave early on September 7, located about 350 mi (565 km) north-northeast of the Suriname-French Guiana border. Satellite imagery indicated that it quickly intensified into Tropical Storm Danielle about 385 mi (620 km) east-southeast of Grenada. On September 8, Hurricane Hunters flew into Tropical Storm Danielle and reported maximum sustained winds of 60 mph (95 km/h), as well as a pressure of 1,000 millibars (30 inHg). The flight also observed wind gusts up to hurricane-force. On September 8, Danielle moved through the Windward Islands and entered the Caribbean Sea, where it weakened due to entrainment of dry air from northern South America. The circulation became dislocated from the convection. Late on September 9, the system weakened to tropical depression status, and the next day it dissipated in the western Caribbean.
As Danielle moved through the Lesser Antilles, it produced wind gusts to near hurricane-force on Saint Vincent, which destroyed the roofs of more than 30 houses and caused a power outage. The combination of winds and heavy rains caused heavy crop damage. Twelve days after Danielle struck, another rainstorm affected Saint Vincent and the Grenadines. The two storms damaged 436 buildings, including 100 that were destroyed, while also killing 120 animals and triggering landslides. Damage from the two storms totaled $9.3 million in the country. On Barbados, 12 homes were destroyed. Wind gusts reached 40 mph (64 km/h) in Bridgetown. A coast guard ship required rescue after it ran aground into a reef in the southern Grenadines. Further south, rainbands from Danielle swept through Trinidad and Tobago, producing up to 4 feet (1.2 m) of flooding. The flooding caused 27 landslides and destroyed 4 bridges. Damage in the country was estimated at $8 million (1986 TTD, $1.2 million 1986 USD). The storm also led to a tropical storm watch on Jamaica, where officials evacuated fishermen from two small islands as a precaution.