The 1998 Atlantic hurricane season was an active, catastrophic, and extremely deadly Atlantic hurricane season, which had the highest number of storm-related fatalities in 2 centuries and ranks as the second-deadliest season on record in the Atlantic, behind the 1780 season. Additionally, the season featured some of the costliest tropical cyclones ever in the basin at the time. The season had above average activity, due to the dissipation of an El Niño event and transition to La Niña conditions. It officially began on June 1 and ended on November 30, dates which conventionally delimit the period during which most tropical cyclones form in the Atlantic Ocean. The season had a rather slow start, with no tropical cyclones forming in June. The first tropical cyclone, Tropical Storm Alex, developed on July 27, one of the latest dates on record to see the formation of the first system in an Atlantic hurricane season. The season's final storm, Hurricane Nicole, became extratropical on December 1.
Several storms made landfall or directly affected land. Hurricane Bonnie made landfall in southeastern North Carolina as a Category 2 hurricane in late August, killing five people and causing about $1 billion in damage. Hurricane Earl caused $79 million in damage and three deaths after making landfall in Florida as a Category 1 hurricane.
The most notable storms were Hurricane Georges and Hurricane Mitch. Georges devastated Saint Kitts and Nevis, Puerto Rico and the Dominican Republic as a major Category 3 storm but peaked as a high-end Category 4 hurricane just before moving through many of the Caribbean Islands before affecting the southern US mainland, making its landfall near Biloxi, Mississippi, causing significant damage and at least 600 confirmed deaths. Mitch was a destructive Category 5 hurricane that affected much of Central America before making landfall in Florida as a tropical storm. It caused significant damage and killed at least 11,000 people in Central America, and was the second deadliest Atlantic hurricane in recorded history, behind only the Great Hurricane of 1780. Georges and Mitch caused $9.37 billion in damage and $6.08 billion USD) in damage, respectively. As a whole, the 1998 Atlantic hurricane season was, at the time, the second-costliest season on record, after the 1992 season.
Season forecasts
In advance of, and during, each hurricane season, several forecasts of hurricane activity are issued by national meteorological services, scientific agencies, and noted hurricane experts. These include forecasters from the United States National Oceanic and Atmospheric Administration (NOAA)'s National Hurricane and Climate Prediction Center's, William M. Gray and his associates at Colorado State University (CSU), as well as Weather Research Center (WRC). The forecasts include weekly and monthly changes in significant factors that help determine the number of tropical storms, hurricanes, and major hurricanes within a particular year.
As stated by NOAA and CSU, an average Atlantic hurricane season between 1981–2010 contains roughly 12 tropical storms, 6 hurricanes, 3 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 began issuing outlooks in December 1997 and initially predicted 9 named storms, 5 hurricanes, and 2 major hurricanes would occur in the upcoming season. Later, in April 1998, CSU released a forecast calling for 10 named storms, 6 hurricanes, and 2 major hurricanes. The predictions by CSU in June and August 1998 remained the same as the forecast in April. Additionally, forecasters at CSU predicted that the El Niño event that began in 1997 would dissipate either before or shortly after the 1998 season began. The WRC predicted 8 named storms and 5 hurricanes in early 1998, but did not include a forecast for the number of major hurricanes.
Seasonal summary
The Atlantic hurricane season officially began on June 1, 1998, with the first tropical cyclone developing on July 27. It was an above average season in which 14 tropical cyclones formed. All fourteen depressions attained tropical storm status and ten of these became a hurricane. Three hurricanes further intensified into major hurricanes. The dissipation of an El Niño in April and the development of a La Niña by June was attributed to the above average activity. Three hurricanes and three tropical storms made landfall during the season and caused at least 19,618 deaths and nearly $17.1 billion in damage. Hurricane Danielle also caused damage in Puerto Rico, although it never made landfall. The last storm of the season, Hurricane Nicole, dissipated on December 1, which was the day after the official season ending on November 30.
Activity in the season began very slowly, with the first tropical cyclone not forming until July 27. It did not become Tropical Storm Alex until July 29, which was an abnormally late first named storm for an Atlantic hurricane season. After a gap in activity for about two weeks, Hurricane Bonnie developed on August 19. Thereafter, tropical cyclogenesis became more frequent, with an additional three storms forming by the end of August. September was the most active month, coinciding with the climatological peak of the season. Six tropical cyclones formed in that month, four of which reached hurricane intensity. Four hurricanes were active on September 26, with Georges over the Straits of Florida, Ivan in the North Atlantic, Jeanne was located near Cape Verde, and Karl was situated over the Central Atlantic. This was the first such occurrence since August 22 in 1893. However, three hurricanes also co-existed in the Atlantic on September 11 in 1961, with a possible fourth. Following a busy September, activity began slowing into October, when only two tropical cyclones developed. However, both storms became a hurricane, with the second cyclone, Hurricane Mitch, becoming the most intense and deadliest storm of the 1998 Atlantic hurricane season.
Overall, the season's activity was reflected with a cumulative accumulated cyclone energy (ACE) rating of 182. 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 34 knots (39 mph; 63 km/h) or tropical storm strength.
Systems
Tropical Storm Alex
A tropical wave emerged off the west coast of Africa on July 26 and rapidly developed a surface circulation by the following day. As a result, it is estimated that Tropical Depression One formed at 1200 UTC on July 27, while centered about 345 miles (555 km) south-southwest of Cape Verde. Initially, minimal change in structure or convection occurred. However, after an increase in deep convection and satellite intensity estimates of 40 mph (64 km/h), the depression was upgraded to Tropical Storm Alex early on July 29. Under the influence of a deep-layer ridge, the storm tracked west to west-northwestward at 12 to 17 mph (19 to 27 km/h). A mid- to upper-level trough located north and west of Alex generated vertical wind shear starting on July 30, allowing for minimal intensification.
Later on July 30, a burst in deep convection resulted in slight strengthening of the storm. At 0000 UTC on July 31, Alex attained its peak intensity with a maximum sustained wind speed of 50 mph (80 km/h) and a minimum atmospheric pressure of 1,000 mbar (30 inHg). Vertical wind shear prevented Alex from strengthening further and instead caused it to weaken later that day. By August 1, the low-level circulation became exposed to the south of the remaining deep convection. Later that day, Alex curved northwestward and avoided any threat to the Lesser Antilles. At 1800 UTC on August 1, the storm was downgraded to a tropical depression. Early on the following day, Alex was considered dissipated after a reconnaissance aircraft failed to locate a closed low-level circulation.
Hurricane Bonnie
Tropical Depression Two developed from a tropical wave at 1200 UTC on August 19, while located well east of the Lesser Antilles. After tracking west-northwestward for 24 hours, the depression was upgraded to Tropical Storm Bonnie. While at tropical storm intensity, Bonnie passed north of Puerto Rico and the Virgin Islands on August 21. Early on the following day, a hurricane hunter aircraft indicated that the storm strengthened into a hurricane. Bonnie curved north-northwestward on August 23, shortly before it peaked with winds of 115 mph (185 km/h). The storm weakened slightly before making landfall near Wilmington, North Carolina with winds of 110 mph (180 km/h) early on August 27. The storm briefly weakened to a tropical storm later on August 27, though it re-strengthened into a hurricane as it was re-emerging into the Atlantic. Colder waters weakened Bonnie to a tropical storm by late on August 28. The storm then accelerated east-northeastward offshore New England and Atlantic Canada, before becoming an extratropical cyclone on August 30.
In South Carolina, strong winds were reported, particularly in Charleston, Georgetown, and Horry Counties. Many trees and power lines were downed in the area; there was also structural damage. The storm caused two deaths and about $25 million in losses in South Carolina. Strong winds lashed Eastern North Carolina, downing numerous trees and power lines, which left about 500,000 people without electricity. One person was killed in Barco when a tree fell on a house. In North Carolina alone, damage reached at least $240 million. Erosion was also severe, with numerous docks, piers, and bulkheads either damaged or destroyed; many protective dunes constructed after Hurricane Fran in 1996 were ruined. In Virginia, strong winds in the eastern portions of the state caused some structural damage and downed trees and power lines, leaving about 750,000 people without electricity.
Damage in Virginia reached approximately $95 million. Two other fatalities were reported, one in Rehoboth Beach, Delaware and the other at Cape Cod, Massachusetts. Later in its duration, Bonnie brought rough seas, strong winds, and light rainfall to Newfoundland and Nova Scotia, but caused little damage. Overall, there were five deaths and at least $720 million in damage, while other sources claimed that losses reached $1 billion.
Tropical Storm Charley
An area of disturbed weather developed into Tropical Depression Three at 0600 UTC on August 21, while located about 305 miles (491 km) east-southeast of Brownsville, Texas. The depression moved generally northwestward throughout its duration. Based on data from oil platforms in the northern Gulf of Mexico, the depression was upgraded to Tropical Storm Charley at 1800 UTC on August 21. The storm intensified further, with reconnaissance aircraft reporting sustained winds of 70 mph (110 km/h) at 0600 UTC on August 22. Shortly thereafter, Charley weakened and only four hours later, it made landfall near Port Aransas, Texas with winds of 45 mph (72 km/h). Late on August 22, the system weakened to a tropical depression. Charley persisted as a tropical cyclone for about 24 hours longer, before dissipating near Del Rio, Texas.
Heavy rainfall was reported throughout southern Texas. Del Rio recorded 17 inches (430 mm) of precipitation in a 24‑hour period, a record for the city. Charley was also responsible for serious local flooding in Val Verde County, Texas, where collectively about 2,000 houses, mobile homes, and apartments were destroyed. In that county alone, damage was estimated at $40 million. Throughout Texas, losses reached about $50 million and 13 deaths were confirmed, with an additional 6 people listed as missing. Flooding also occurred in northern Mexico, especially in the state of Coahuila. Ciudad Acuña was inundated with up to 6 feet (1.8 m) of water, which damaged about 450 houses in the city; seven deaths were also reported in the area.
Hurricane Danielle
A tropical wave emerged off the western coast of Africa on August 21. The wave moved west-northwestward, steered by the Azores High to its north. It produced an area of convection, which developed into a tropical depression on August 24 about 690 miles (1,110 km) west-southwest of the Cape Verde Islands. The depression quickly organized into Tropical Storm Danielle. A pinhole eye developed in the convection, and Danielle attained hurricane status on August 25. Early on August 26, Danielle attained its maximum sustained wind speed of 105 mph (169 km/h), one of four peak intensities. Soon thereafter, the eye became obscured and southeasterly vertical wind shear increased, and the hurricane weakened. The storm briefly re-strengthened slightly on August 27 and reached peak winds for a second time. Vertical wind shear persisted and Danielle soon began to weaken again, partly due to upwelling from Hurricane Bonnie roughly a week earlier.
By early on August 30, Danielle had weakened to the extent that it was only a minimal hurricane. Around that time, an anticyclone near Bermuda caused Danielle to curve northeastward. The hurricane re-intensified and reached its peak intensity for a third time on August 31. It weakened slightly again before attaining peak winds for a fourth and final time on September 1. On the next day, Danielle passed about 105 mi (170 km) north of Bermuda. Early on September 3, Danielle reached its minimum barometric pressure of 960 mbar (960 hPa; 28 inHg). On the next day, Danielle transitioned into an extratropical cyclone while located east-southeast of Newfoundland. The remnants of Danielle continued to the northeast, merging with an extratropical low pressure area north of Ireland on September 8.