The 2016 Atlantic hurricane season was the first above-average hurricane season since 2012, producing 15 named storms, 7 hurricanes and 4 major hurricanes. The season officially started on June 1 and ended on November 30, though the first storm, Hurricane Alex which formed in the Northeastern Atlantic, developed on January 12, being the first hurricane to develop in January since 1938. The final storm, Otto, crossed into the Eastern Pacific on November 25, a few days before the official end. Following Alex, Tropical Storm Bonnie brought flooding to South Carolina and portions of North Carolina. Tropical Storm Colin in early June brought minor flooding and wind damage to parts of the Southeastern United States, especially Florida. Hurricane Earl left 94 fatalities in the Dominican Republic and Mexico, 81 of which occurred in the latter. In early September, Hurricane Hermine, the first hurricane to make landfall in Florida since Hurricane Wilma in 2005, brought extensive coastal flooding damage especially to the Forgotten and Nature coasts of Florida. Hermine was responsible for five fatalities and about $550 million (2016 USD) in damage.
The strongest, costliest, and deadliest storm of the season was Hurricane Matthew, the southernmost Category 5 Atlantic hurricane on record and the first to reach that intensity since Felix in 2007, ending the longest streak of seasons without a hurricane of such intensity in the satellite era. With at least 603 deaths attributed to it, Matthew was the deadliest Atlantic hurricane since Stan of 2005. Furthermore, damage from Matthew is estimated to be at least $16.5 billion, making it the ninth costliest Atlantic hurricane on record at the time. Hurricane Nicole became the first major hurricane to directly impact Bermuda since Hurricane Fabian in 2003, leaving widespread but relatively moderate damage on the island. The final tropical cyclone of the season – Hurricane Otto – brought severe flooding to Central America in November, particularly in Costa Rica and Nicaragua. Otto left 23 deaths and about $190 million in damage. On November 25, the storm emerged into the Eastern Pacific basin, the first such occurrence since Hurricane Cesar–Douglas in 1996. Most of the season's tropical cyclones impacted land, and nine of those storms caused loss of life. Collectively, the storms left at least 736 fatalities and $17.49 billion in damage, making the season the costliest since 2012.
Most forecasting groups predicted above average activity in anticipation of a dissipating El Niño event and the development of a La Niña, as well as warmer than normal sea surface temperatures. Overall, the forecasts were fairly accurate.
Seasonal forecasts
Ahead of and during the season, several meteorological services and scientific agencies forecast how many named storms, hurricanes, and major hurricanes will form during a season, and/or how many tropical cyclones will affect a particular country. These agencies include the Tropical Storm Risk (TSR) Consortium of the University College London, the National Oceanic and Atmospheric Administration (NOAA), United Kingdom Met Office (UKMO), Coastal Carolina University (CCU), Colorado State University (CSU), and North Carolina State University (NCSU). 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. Some of these forecasts also take into consideration what happened in previous seasons and the predicted weakening of the 2014–2016 El Niño event. On average, an Atlantic hurricane season between 1981 and 2010 contained twelve tropical storms, six hurricanes, and two major hurricanes, with an accumulated cyclone energy (ACE) index of between 66 and 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 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.
Pre-season forecasts
The first forecast for the year was issued by CSU on December 11, who anticipated that one of four different scenarios could occur. The scenario considered most likely was that Atlantic multidecadal oscillation (AMO) and thermohaline circulation (THC) would be stronger, but effects from El Niño would remain, resulting in a slightly above average season. The next most likely scenario was that both the AMO and THC would strengthen and the El Niño effects would cease to exist, causing a well above average season. In the other two scenarios, which were given the same probability of occurrence, the AMO and THC would weaken and the effects of El Niño would either disappear or some would remain, resulting in either a near average or well below average season.
TSR subsequently issued their first outlook for the 2016 season during December 16, 2015 and predicted that activity would be about 20% below the 1950–2015 average, or about 15% below the 2005–2015 average. Specifically they thought that there would be 13 tropical storms, 5 hurricanes, 2 major hurricanes and an ACE index of 79 units. A few months later, TSR issued their second prediction for the season during April 6, 2016 and lowered the predicted number of named storms to 12 but raised the number of hurricanes to 6. On April 14, CSU predicted that the season would be near-normal, predicting 13 named storms, 6 hurricanes and 2 major hurricanes with ACE near 93. On April 15, NCSU predicted the season would be very active, with 15–18 named storms, 8–11 hurricanes and 3–5 major hurricanes. A month later, the UKMO released its forecast, predicting a slightly above-average season with 14 named storms and 8 hurricanes. It also predicted an ACE index of 125, above the defined average ACE index at 103.
On May 27, NOAA issued its first outlook calling for a near-normal season with a 70% chance that 10–16 named storms could form, including 4–8 hurricanes of which 1–4 could reach major hurricane status. NOAA also stated that there is a 45% chance of a near-normal season, 30% chance of an above-normal season and 25% chance of a below-normal season. Also on May 27, TSR substantially increased their forecast numbers, predicting activity would be about 30% above the average with 17 named storms, 9 hurricanes, 4 major hurricanes and an ACE near 130. The reason for the increased activity forecast was the increased likelihood of La Niña forming during the season in addition to a trend towards a negative North Atlantic Oscillation, which generally favors a warmer tropical Atlantic. TSR predicted that there is a 57% chance that the 2016 Atlantic season would be above-normal, a 33% chance it would be near-normal, and only a 10% chance it would be below-normal.
Mid-season outlooks
CSU updated their forecast on June 1 to include 14 named storms, 6 hurricanes and 2 major hurricanes to include Tropical Storm Bonnie. It was again updated on July 1 to include 15 named storms, 6 hurricanes and 2 major hurricanes, to accommodate for tropical storms Colin and Danielle. On July 5, TSR released their fourth forecast for the season, slightly lowering the predicted numbers to 16 tropical storms, 8 hurricanes and 3 major hurricanes. On August 5, TSR released their final forecast for the season, lowering the numbers to 15 named storms and 7 hurricanes due to the influence of La Niña being less than anticipated previously. NOAA updated their forecast on August 11, increasing their predictions to 12–17 named storms, 5–8 hurricanes, and 2–4 major hurricanes.
Seasonal summary
The 2016 Atlantic hurricane season officially began on June 1, 2016. It was an above average season and the most active since 2012, producing a total of 15 named storms, 7 hurricanes, and 4 major hurricanes. The first storm, Hurricane Alex, developed on January 12, while the final system, Hurricane Otto, made a crossover to the Eastern Pacific on November 25. The higher-than-normal activity was attributed to many factors. Most significantly, one of the strongest El Niño events recorded in history rapidly dissipated, transforming to cool-neutral conditions across the Pacific in late summer. This led to warmer than normal sea surface temperatures across the Atlantic, though the subtropical regions were slightly cooler than normal; slightly lower than normal sea level pressures; and reduced wind shear, especially in the Caribbean, which had experienced record values of wind shear in the past recent years. Moisture levels, however, were anomalously dry, which likely prevented some of the storms from becoming significant hurricanes. Steering currents had also been different from past years, which had previously had a trough of low pressure dominating the East Coast of the United States. The tropical cyclones of this season caused about $16.1 billion in damage and at least 748 deaths, being the costliest season since 2012, the deadliest since 2008. The Atlantic hurricane season officially ended on November 30, 2016.
The year opened up with an anomalous storm in January: Hurricane Alex, the first system of such intensity to develop in January since 1938. Activity picked up at the end of May into June, with three consecutive tropical storms: Bonnie, Colin, and Danielle. The latter two became the earliest third- and fourth-named storms on record respectively. July saw no storm development for the first time in four years, however. August saw the formation of five tropical cyclones, including Earl, Fiona, Gaston, Eight, and Hermine. A Category 1 hurricane, Earl wrought tremendous damage in Belize and Mexico. With 81 lives lost in Mexico during the passage of Earl, it was the deadliest Atlantic hurricane in the country since 2005. Gaston became the season's first major hurricane on August 28, attaining peak winds of 120 mph (195 km/h) over the central Atlantic. On September 1, Hermine struck the Florida Peninsula as a Category 1 hurricane, ending an 11-year drought of hurricane landfalls in the state, which began after Hurricane Wilma in October 2005.
September featured another five tropical cyclones: Ian, Julia, Karl, Lisa, and Matthew, the latter of which persisted into October. Matthew proved to be the most significant storm of the season, becoming the first Category 5 hurricane in the Atlantic since Hurricane Felix in 2007, and, with a death toll of over 700, it was the deadliest in the Atlantic basin since Hurricane Stan in 2005. It subsequently struck Haiti as a Category 4 hurricane, and inflicted catastrophic damage across the impoverished nation. Matthew also caused extensive damage in Cuba, the Bahamas, and the Southeastern United States. Concurrently, Hurricane Nicole meandered south of Bermuda for more than a week before making a direct hit on the territory as a major hurricane. The next four weeks were quiet, until Hurricane Otto formed in the southwestern Caribbean during late November. Otto eventually became the latest-forming major hurricane in the Atlantic basin on record, surpassing a storm in 1934. After striking Nicaragua and becoming the first hurricane on record to pass over Costa Rica, Otto – the final tropical cyclone of the season – then emerged into the Eastern Pacific basin on November 25, the first such occurrence since Hurricane Cesar–Douglas in 1996.
The season's activity was reflected with an accumulated cyclone energy index of 142.5 units, which was well above the 1981–2010 median of 92, as well as the highest value since 2010.
Systems
Hurricane Alex
A weak area of low pressure developed over northwestern Cuba in association with a stationary front on January 6. The frontal wave intensified as it moved into the central Atlantic, temporarily attaining hurricane-force winds by January 10. Steered by anomalous high pressure, the disturbance turned southeast and tracked over warmer waters. Its associated fronts dissipated, its wind field became more symmetric, and convection increased near the center, leading to the formation of Subtropical Storm Alex by 18:00 UTC on January 12. Despite marginal ocean temperatures, Alex benefited from rapidly cooling upper-air temperatures, and it intensified quickly while turning northeast. The presence of deeper convection near the center and an eye on conventional satellite showcased the storm's transition into a fully tropical cyclone and intensification into a hurricane by 06:00 UTC on January 14. Six hours later, it peaked with maximum sustained winds of 85 mph (135 km/h). Alex turned north after peak, and the storm weakened to a tropical storm before making landfall on Terceira Island, Azores. With decreasing core convection and an impinging warm front, Alex transitioned into an extratropical cyclone by 18:00 UTC on January 15 and was absorbed by a larger extratropical low two days later.
The precursor disturbance to Hurricane Alex produced gusts up to 60 mph (95 km/h) on Bermuda, as well as swells up to 20 ft (6 m) offshore; this disrupted air travel, downed trees, caused sporadic power outages, and suspended ferry services. In the Azores, the cyclone produced maximum rainfall accumulations up to 4.04 in (103 mm) in Lagoa. Peak gusts of 57 mph (92 km/h) affected Ponta Delgada, causing minor to moderate damage. Landslides also contributed to minor damage. One death occurred when a victim that suffered a heart attack was unable to be airlifted to a hospital due to unsettled conditions.