The 1997 Atlantic hurricane season was a below-average hurricane season. It officially began on June 1, and lasted until November 30 of that year. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. The 1997 season was fairly inactive, with only seven named storms forming, with an additional tropical depression and an unnumbered subtropical storm. It was the first time since the 1961 season that there were no active tropical cyclones in the Atlantic basin during the entire month of August—historically one of the more active months of the season—a phenomenon that would not occur again until 2022. A strong El Niño is credited with reducing activity in the Atlantic, while increasing the number of storms in the eastern and western Pacific basins to 19 and 26 storms, respectively. As is common in El Niño years, tropical cyclogenesis was suppressed in the tropical latitudes, with only two becoming tropical storms south of 25°N.
The first system, an operationally unnoticed subtropical storm, developed north of the Bahamas on June 1 and dissipated by the following day without any impact. Tropical Storm Ana developed offshore South Carolina on June 30 and dissipated on July 4, after causing minor affects in North Carolina. Hurricane Bill was a short-lived storm that lasted from July 11 to July 13 and produced light rainfall in Newfoundland. As Bill was dissipating, Tropical Storm Claudette developed and generated rough seas in North Carolina. The most devastating storm was Hurricane Danny, which caused extensive flooding, particularly in southern Alabama. Danny resulted in 9 fatalities and about $100 million (1997 USD) in damage. The outer bands of Hurricane Erika brought rough seas and gusty winds to the Lesser Antilles, resulting in two deaths and $10 million in losses. The precursor to Tropical Storm Grace caused flooding in Puerto Rico, while Tropical Depression Five and Tropical Storm Fabian did not impact any land. Collectively, the storms of the 1997 Atlantic hurricane season resulted in 12 fatalities and approximately $111.46 million in damages.
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), as well as the Weather Prediction Center (WPC). As stated by the National Oceanic and Atmospheric Administration (NOAA), an Atlantic hurricane season between 1981–2010 contained roughly twelve tropical storms, six hurricanes, three major hurricanes, and an accumulated cyclone energy (ACE) index of 66–103 units. NOAA typically categorizes a season as either above-average, average, of below-average based on the cumulative ACE Index; however, the number of tropical storms, hurricanes, and major hurricanes within a hurricane season is considered occasionally as well.
CSU's first outlook for the season, issued in December 1996, predicted eleven named storms, seven hurricanes, and three major hurricanes, which are defined as a tropical cyclone reaching at least a Category 3 rating on the Saffir–Simpson Hurricane Scale. These numbers went unchanged during their forecast updates released in April and May. CSU issued these predictions based on the possibility of El Niño weakening, a cessation of drought conditions over the Sahel, and nearly identical trade wind and atmospheric pressure patterns compared to the previous season. In August, however, CSU slightly decreased their predicted number of hurricanes and major hurricanes to six and two, respectively, after the El Niño strengthened instead. In early 1997, the WRC anticipated a less active season, forecasting seven named storms and four hurricanes, but issuing no prediction on the number of major hurricanes.
Seasonal summary
The Atlantic hurricane season officially began on June 1, and an unnamed subtropical storm developed on the same day. Only nine tropical depressions formed. Eight of the depressions attained tropical storm status, making 1997 the least active Atlantic hurricane season in the ongoing above-average era of tropical cyclogenesis, which began in 1995. Just three of these systems attained hurricane status and only one tropical cyclone intensified into a major hurricane, which was below the 1981–2010 average of three per season. Only Danny made landfall at hurricane strength during the season, although Hurricane Erika and Tropical Storm Grace also caused damage and fatalities. Those three cyclones collectively caused 12 deaths and $111.46 million in damage. The last storm of the season, Tropical Storm Grace, dissipated on October 17, over a month before the official end of the season on November 30.
The 1997 Atlantic hurricane season had a very active beginning. In June, two tropical cyclones developed – the unnoticed subtropical storm and Tropical Storm Ana. An unusual four tropical cyclones formed in the month of July, three of which reached tropical storm intensity, and two of them became hurricanes. Despite the active start, the other months of the season featured record low activity, especially in August and September, both of which combined produced only one tropical cyclone. As a result of the active start and subsequent lack of activity, it showed that early season activity has no correlation to the entire season. Further, this marked the first occurrence of no tropical cyclogenesis in August since 1961, and the most recent instance of no activity in that month until 2022. The lone tropical cyclone during the period was Hurricane Erika, which developed on September 3. In October, two short-lived tropical cyclones developed, Fabian and Grace. Tropical cyclogenesis ceased after Grace transitioned into an extratropical cyclone on October 17.
The season's activity was reflected with a low accumulated cyclone energy (ACE) rating of 41. 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. It is only calculated for full advisories on tropical systems at or exceeding 39 mph (63 km/h), which is the threshold for tropical storm strength.
Systems
Unnumbered subtropical storm
A cluster of thunderstorms developed over Florida in late May. A shortwave trough brought it to the northeast, enhancing convection around a developing center of circulation. The low pressure area, which formed on May 31, developed into a subtropical depression on June 1. Operationally, it was treated as a frontal low, but post-analysis suggested it remained separate throughout its lifetime, and was classified as an unnamed subtropical storm. It reached subtropical storm strength six hours later as it moved rapidly parallel to the East Coast of the United States. The convection continued to wrap around the center, and despite unfavorable conditions from an approaching cold front it continued to intensify. Late on June 1, it reached its peak intensity with maximum sustained winds of 50 mph (85 km/h) while off the coast of North Carolina. The storm turned to the east, and transitioned extratropical late on June 2 southeast of Massachusetts. Shortly thereafter, the remnants of the storm merged with a cold front.
Tropical Storm Ana
A frontal low pressure system off the coast of South Carolina developed into Tropical Depression One at 1200 UTC on June 30. It moved slowly eastward, and attained tropical storm status on July 1. After becoming a tropical storm, Ana slightly intensified. Early on July 2, Ana attained its peak intensity with maximum sustained winds of 45 mph (75 km/h) and a minimum central pressure of 1,000 mbar (30 inHg). Later on July 2, a shortwave trough forced Ana to northeastward, into a region of increasing vertical wind shear. Simultaneously, Ana began to weaken, as it was moving into an area of decreasing sea surface temperatures.
By late on July 3, Ana weakened to a tropical depression. The storm also lost tropical characteristics and transitioned into an extratropical cyclone early on July 4, over the western Atlantic Ocean. The extratropical remnants persisted until dissipating about twenty-four hours later. Minimal impact was reported as a result of Ana, other than rip currents in coastal North Carolina. Due to the rough seas, 14 rescues and one serious injury occurred at Carolina Beach. In addition, five rescues were made at Kure Beach and at least one person was hospitalized. However, there were no fatalities at either location.
Hurricane Bill
A large upper-level low separated from a trough north of Puerto Rico in early July. Convection increased on July 7 after a surface trough developed, and a low pressure area formed east of the Bahamas once the upper-level low retreated to the southwest. Wind shear decreased across the region, allowing the convection to increase and organize, and it is estimated the system developed into a tropical depression on July 11 about 330 mi (530 km) southwest of Bermuda. After developing, the cyclone moved northeastward in advance of an approaching cold front. It quickly intensified into Tropical Storm Bill, and briefly threatened to pass near Bermuda. As a result, a tropical storm warning was issued, although it was quickly dropped; there was no impact on the island from Bill.
Bill quickly intensified as it continued northeastward. By midday on July 12, an eye feature was observed on satellite images, which suggested that Bill intensified into hurricane status at a relatively high latitude. Bill had in fact intensified into a hurricane, and the storm had attained its peak intensity with maximum sustained winds of 75 mph (120 km/h) and a minimum pressure of 986 mbar (29.1 inHg). After only 12 hours at hurricane status, Bill weakened back to tropical storm status, and on July 13 was absorbed by the cold front about 185 mi (300 km) south of Cape Race, Newfoundland. Bill dropped very light rainfall on Newfoundland, peaking at slightly less than 1 in (25 mm).
Tropical Storm Claudette
The frontal system that influenced the track of Hurricane Bill spawned a non-tropical low off the southeast United States on July 11. The low remained nearly stationary as the front dissipated, and it developed into Tropical Depression Three on July 13 about 325 mi (525 km) south-southeast of Wilmington, North Carolina. The depression quickly intensified into Tropical Storm Claudette, based on reconnaissance aircraft data. It moved northeastward, passing southeast of the Outer Banks. Despite the presence of wind shear it developed banding features. On July 14, the storm reached peak winds of 45 mph (75 km/h). Thereafter, Claudette turned eastward ahead of a frontal system.
Its associated thunderstorm activity was sporadic and relatively disorganized, and the storm weakened to a tropical depression on July 16. Claudette briefly re-intensified into a tropical storm before becoming extratropical later that day. Shortly thereafter, it merged with a cold front, while the remnants were last noted near the Azores on July 23. Tropical Storm Claudette had minimal effects on land. Severe rip currents from Claudette in North Carolina caused several rescues and one person was injured, although no fatalities occurred. Some residents of coastal North Carolina were even disappointed that Claudette was to remain offshore, as the region was suffering from dry conditions.
Hurricane Danny
A tropical low over the northern Gulf of Mexico developed into Tropical Depression Four on July 16. The depression headed slowly east-northeastward, and intensified into Tropical Storm Danny on the following day. Danny continued east-northeastward, and reached hurricane strength just before landfall near Buras, Louisiana. Because of the narrowness of that piece of land, most of Danny remained over water and it lost little strength. Danny re-emerged into the Gulf of Mexico, and strengthened slightly making two landfalls in Alabama as a low-end Category 1 hurricane on July 19. After remaining stationary for a day, Danny moved northward and weakened to a tropical depression. Heading northward across Alabama, Danny turned to the east and crossed over the Southeastern United States. While centered over North Carolina, Danny interacted with a developing trough, which caused it to re-intensify into a tropical storm. Shortly thereafter, Danny emerged over the Atlantic Ocean near the North Carolina–Virginia border on July 24. Danny took a northward turn, and came within 30 mi (50 km) of Nantucket Island on July 26. It then turned out to sea and was absorbed by a front on July 27.
Although Danny was a hurricane upon landfall, strong winds were confined to a small area, with only portions of extreme eastern Louisiana reporting hurricane-force winds. Danny also dropped torrential amounts of rain in Louisiana, peaking at 11.40 in (290 mm) in Buras-Triumph. Flooding occurred in portions of the state due to heavy rainfall. The floods and high winds produced by Danny damaged over 300 houses and more than 170 businesses in Louisiana alone. In Mississippi, Danny dropped heavy rainfall on the southern portion of the state, resulting in minor street and house flooding. As Danny crossed Dauphin Island, Alabama on July 19, it dropped 37.75 in (960 mm) of rain. This made Danny the wettest tropical cyclone on record in Alabama. Hurricane force-winds were reported on Dauphin Island and the western shores of Mobile Bay. In the same area, many buildings had sustained roof damage. In addition, many homes on the Fowl and Fish Rivers reported significant damage. Further north in South Carolina and Virginia, Danny spawned several tornadoes; some of them caused significant damage. Heavy rainfall also occurred in some isolated areas; in central North Carolina between 8–12 in (200–300 mm) of rain was reported. Danny eventually affected Massachusetts, bring light rainfall and tropical storm-force winds to the southeastern portions of the state. Overall, Danny caused nine fatalities, and approximately $100 million in damage.