Lably
Skip to content

2015 Atlantic hurricane season

  • 25 min read
  • 5 chapters

Explore on Lably

ToursExplore Lably’s 3D tours

Although most of the storms impacted land, overall effects were minimal. Ana caused minor flooding and wind damage in the Carolinas and left two dead in North Carolina. Tropical Storm Bill and its remnants caused flooding primarily in the South Central, Midwestern, and Mid-Atlantic regions of the United States, while its precursor also left flooding in Central America and Mexico. The storm resulted in two deaths in Honduras, two in Guatemala, one in Mexico, and three deaths in the United States. Additionally, the United States suffered at least $100 million (2015 USD) in damage. Claudette and Danny left very minimal impact on land. In late August, Tropical Storm Erika brought heavy rainfall to Dominica, leading to devastating floods. Erika caused nearly $500 million in damage and 30 fatalities, making it, at the time, the island's deadliest natural disaster since Hurricane David in 1979. The storm also flooded other nearby islands, but to a much lesser degree, such as Guadeloupe, Puerto Rico, and Hispaniola. Five additional deaths occurred in Haiti.

Fred prompted a hurricane warning for Cape Verde for the first time ever and was the first storm to pass through the islands as a hurricane since 1892. Strong winds there left about $2.5 million in damage. Two deaths were presumed to have occurred after two fishermen never returned to port. Seven other sailors likely drowned offshore Guinea-Bissau after their fishing boat collapsed. Tropical storms Grace, Henri, and Ida left negligible impact on land. Hurricane Joaquin's intensity and slow movement in the vicinity of the Bahamas resulted in severe damage on some islands. Additionally, the American cargo ship SS El Faro went missing near Crooked Island and eventually capsized during the storm, drowning 33 people. Rough seas in Haiti also caused damage and one death from a fisherman drowning. Joaquin was the most intense satellite era tropical cyclone of non-tropical origins. The remnants of Kate affected the British Isles, particularly Wales in the United Kingdom. Throughout the season, these storms collectively caused $733.81 million in damage and 89 deaths.

With the exception of Tropical Storm Risk's initial season prediction in December 2014, all major forecasting agencies called for a below or near-average season, due to the strong 2014–16 El Niño event and colder than average sea surface temperatures. Overall, the forecasts were fairly accurate.

Seasonal 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, Tropical Storm Risk, the United Kingdom's Met Office, and Philip J. Klotzbach, William M. Gray and their associates at Colorado State University (CSU). 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. According to NOAA and CSU, the average Atlantic hurricane season between 1981 and 2010 contained roughly 12 tropical storms, six hurricanes, three major hurricanes, and an accumulated cyclone energy (ACE) index of 66–103 units. Broadly speaking, ACE is a measure of the power of a tropical or subtropical storm multiplied by the length of time it existed. Therefore, a storm with a longer duration or stronger intensity will have high values of ACE. It is only calculated for full advisories on specific tropical and subtropical systems reaching or exceeding wind speeds of 39 mph (63 km/h). Accordingly, tropical depressions are not included here. After the storm has dissipated, typically after the end of the season, the NHC reexamines the data, and produces a final report on each storm. These revisions can lead to a revised ACE total either upward or downward compared to the operational value. NOAA typically categorizes a season as either above-average, average, or below-average based on the cumulative ACE Index, but the number of tropical storms, hurricanes, and major hurricanes within a hurricane season are considered occasionally as well.

Pre-season forecasts

On December 9, 2014, Tropical Storm Risk (TSR), a public consortium consisting of experts on insurance, risk management, and seasonal climate forecasting at University College London, issued its first outlook on seasonal hurricane activity during the 2015 season. In its report, the organization forecast activity about 20% below the 1950–2014 average, or about 30% below the 2005–2014 average, totaling to 13 (±4) tropical storms, 6 (±3) hurricanes, 2 (±2) major hurricanes, and a cumulative ACE index of 79 (±58) units. This forecast was largely based on an enhancement of low-level trade winds across the tropical Atlantic during the July to September period. TSR's report stressed that uncertainty in this forecast existed due to the unpredictability in the El Niño–Southern Oscillation and North Atlantic sea surface temperatures.

A few months later, on April 9, 2015, TSR updated its report, detailing its prediction of activity 45% below the 1950–2014 average, or about 50% below the recent 2005–2014 average, with 11 named storms, 5 hurricanes, 2 major hurricanes, and a cumulative ACE index of 56 units. TSR cited what were expected to be cooler than average ocean temperatures across the tropical North Atlantic and Caribbean Sea as reasoning for lower activity. In addition, the report stated that if the ACE forecast for 2015 were to verify, the total values during the three-year period from 2013 to 2015 would be the lowest since 1992–1994, signalling a possible end to the active phase of Atlantic hurricane activity that began in 1995.

On April 9, CSU also released its first quantitative forecast for the 2015 hurricane season, predicting 7 named storms, 3 hurricanes, 1 major hurricane, and a cumulative ACE index of 40 units. The combination of cooler than average waters in the tropical and subtropical Atlantic, as well as a developing El Niño predicted to reach at least moderate intensity, were expected to favor one of the least active seasons since the mid-1990s. The probabilities of a major hurricane striking various coastal areas across the Atlantic were lower than average, although CSU stressed that it only takes one landfalling hurricane to make it an active season for residents involved. On April 13, North Carolina State University (NCSU) released its forecast, predicting a near record-low season with just 4 to 6 named storms, 1 to 3 hurricanes, and 1 major hurricane.

On May 21, the United Kingdom Met Office (UKMO) issued its forecast, predicting a season with below-normal activity. It predicted 8 storms, with a 70% chance that the number of storms would be between 6 and 10; it predicted 5 hurricanes, with a 70% chance that that number would fall in the range of 3 to 7. UKMO's ACE index prediction was 74 units, with a 70% chance of the index falling in the range of 40 to 108 units. On May 27, NOAA released its seasonal forecast, predicting a below-normal season with 6 to 11 named storms, 3 to 6 hurricanes, and 0 to 2 major hurricanes. NOAA indicated that there was a 70% chance of a below-normal season, a 20% chance of a near-normal season, and a 10% chance of an above-normal season.

Mid-season outlooks

On June 1, CSU released an updated forecast, increasing the number of predicted named storms to 8, due to the early formation of Tropical Storm Ana, while keeping the predictions for hurricanes and major hurricanes at 3 and 1, respectively; the ACE index forecast was also kept at 40 units. Probabilities of a major hurricane making landfall on various coastal areas remained below average. CSU's third forecast, issued on July 1, remained unchanged. The fourth and final forecast issued by CSU on August 4 again predicted eight named storms and one major hurricane, but the number of hurricanes was decreased to two. On August 5, TSR updated their forecast and lowered the number of hurricanes developing within the basin to 4, with only 1 forecasted to be a major hurricane. The ACE index was also reduced to 44 units.

Sign in to keep reading

4 more chapters are free with a Lably account.

More in Earth science