Hurricane Matthew nearing Category 5 intensity on the night of Sept. 30. (B. McNoldy)

The 2016 Atlantic hurricane season officially ends on Wednesday, and it was certainly a memorable season and a long one, from Hurricane Alex in January to Hurricane Matthew in October to Hurricane Otto over Thanksgiving.

The overall activity was the highest we’ve seen since 2010 and included several record-breaking events. It may have also been the deadliest hurricane season since 2005 with perhaps 1,700 or more fatalities*. The season ended with 15 named storms (normal is 12), seven hurricanes (normal is 6), three major hurricanes (normal is between 2 and 3), and 130 percent of the average season’s accumulated cyclone energy (ACE).

Tracks of the 16 tropical cyclones that formed in the Atlantic this year. Tracks are color-coded by intensity, and the peak wind and minimum central pressure of each storm are listed in the top right. (B. McNoldy)

Matthew was the most memorable and most destructive storm

Matthew’s track, warnings and wind swatch over its lifetime. (I. Livingston)

Of all of 2016’s storms, Hurricane Matthew was the showstopper.

Matthew formed from an easterly wave near the Windward Islands in late September. It explosively intensified to a Category 5 hurricane in the central Caribbean, becoming the first Category 5 storm in the Atlantic since 2007 and the southernmost Category 5 storm on record.

Next, Matthew made an abrupt right turn and slammed into the southwest coast of Haiti, passed over eastern Cuba and then the Bahamas, all as a Category 3-4 hurricane. The storm wrought massive destruction and was blamed for hundreds of fatalities in Haiti.

Radar image of Hurricane Matthew when the eye was just 35 miles east of Cape Canaveral. (NOAA and B. McNoldy)

Florida’s east coast had a perilous encounter with the storm, and while it was rocked by hurricane-force wind gusts and a storm surge several feet high, it was spared the worst since Matthew’s most powerful winds remained just miles offshore.

Before it finally weakened to a Category 2 hurricane near Jacksonville, Matthew spent an astounding 7.25 days as a major hurricane, the longest stretch on record for a late-season storm, and the fifth longest stretch for any storm (the top four occurred in late August and September).

But Matthew’s closing act was its most devastating for the United States. As it tracked along the curved coastline from Georgia to North Carolina, it dumped extremely heavy rain and generated a record-setting storm surge in some locations.

Eastern North Carolina experienced disastrous inland flooding from up to 15 inches of rain. Emergency officials conducted 2,000 rescues of people stranded in high water. Nearly half of the state’s 100 counties were in a state of emergency, and 52 shelters housed more than 4,300 displaced people.

Fuel tanks are seen after floodwaters rose because of Hurricane Matthew in Lumberton, N.C. (Chris Keane/Reuters)

How the season evolved

The season got off to an abnormally active start with Hurricane Alex in the northeast Atlantic. It formed on Jan. 13, passed through the Azores as a Category 1 hurricane and tropical storm, and lost its tropical characteristics on Jan. 15.

While one could argue Alex was actually a remnant of the 2015 hurricane season, it officially counts as part of the 2016 season. It was the first hurricane to form in January since 1938.

Tropical Storm Alex in the Azores on Jan. 15. (NRLMRY)

The next four storms also made landfall: Tropical Storm Bonnie hit South Carolina, Tropical Storm Colin hit Florida, Tropical Storm Danielle hit Mexico, and Hurricane Earl hit Belize. Bonnie formed and dissipated before the official beginning of the season. Colin and Danielle were the earliest third and fourth named storm formations on record.

Fiona was a short-lived tropical storm in the central Atlantic, but then Gaston formed in approximately the same location a few days later and strengthened into the season’s first major hurricane (defined to be Category 3 or higher on the Saffir-Simpson scale).

Hermine formed between the Florida Keys and Cuba in late August, tracked westward into the Gulf of Mexico, and then turned to the northeast. It intensified to a Category 1 hurricane as it approached Florida’s “Big Bend” coast and made landfall as a hurricane, finally ending that state’s record 10.8-year hurricane “drought.”

Hurricane Hermine making landfall in Florida on the morning of Sep 2, ending the almost-11-year hurricane drought in that state.
Hurricane Hermine making landfall in northern Florida on the morning of Sept. 2, ending the almost-11-year hurricane drought in that state. (NOAA)

Ian, Julia, Karl and Lisa were next in line, and were generally not very eventful or memorable, although Julia was unusual in that it formed over land in northeast Florida and spent its first 12 hours inland.

Nicole spent a good portion of its lifetime overshadowed by Matthew, though it also became a major hurricane. It approached Bermuda as a Category 4 hurricane, then passed over the island as a Category 3 hurricane, the strongest encounter on that island since 2003.

Hurricane Nicole passing over Bermuda on Oct. 13. (Bermuda Weather Service and B. McNoldy)

Otto formed in the southwest Caribbean in late November, passed just north of Panama, then intensified to a Category 2 hurricane as it made landfall in southern Nicaragua — the southernmost hurricane landfall in Central America. It was the latest hurricane formation in the Caribbean, and the first storm to cross from the Atlantic over to the east Pacific as an intact tropical cyclone since 1996.

Hurricane Otto making landfall near Nicaragua’s southern border on Nov. 24.

A review of preseason forecasts

Entering the season, many forecasters were expecting activity to be close to or slightly above average. Looking back at the NOAA outlook published on May 27, it predicted a 70 percent probability of 10-16 named storms, 4-8 hurricanes, 1-4 major hurricanes, and 65-140 percent of the median ACE. These are admittedly rather large and safe ranges, but 2016’s values did fit into the upper end of that outlook.

The company WeatherBell Analytics had a good year with its May outlook, while Colorado State University, the pioneer of hurricane seasonal forecasting, was a bit on the low side in its June outlook.

The chart below shows the timeline of the cumulative ACE values for an average season as well as for 2016. The biggest “deficit” in ACE this year occurred during September, which is on average the peak of hurricane season. But a surge in activity during October (Matthew and Nicole) pushed the values well above average.

Time series of the cumulative ACE values during an average season (purple curve) and during 2016 (yellow curve).

‘Major’ hurricane drought continues

Despite the active season, the major hurricane “drought” — that is the 11-year stretch without a Category 3 or higher storm making landfall in the United States — still stands. The last major hurricane to hit the United States was Wilma in October 2005.

While there have been several costly and deadly hurricane landfalls since then, they did not come with the damaging winds associated with Category 3, 4, and 5 storms. As I wrote in October: “If you have experienced the devastation caused by just the water-based facets of Category 1-2 hurricanes such as Ike, Irene, Sandy, and Matthew in the U.S., you can appreciate that a hurricane of any intensity means business. But the stakes are increased even higher when the destructive wind speeds are added from a Category 3+ hurricane.”

Amount of time between successive major hurricane landfalls in the United States.

Looking ahead to 2017

We are now six months from the 2017 hurricane season, and the first few names on the list of storms are Arlene, Bret, and Cindy. The only new name on the list is Irma, which replaces Irene (retired after slamming the Mid-Atlantic and Northeast 2011). The 2017 list was first used in 1981, and of the 21 original names, 13 are still in circulation.

* The specific number of fatalities is uncertain due to varying estimates for deaths in Haiti from Hurricane Matthew — ranging from around 500 to well over 1,000.