2017 Atlantic hurricane season (Sassmaster15/Money Hurricane/CobraStrike)

The 2017 Atlantic hurricane season became one of the most active hurricane seasons on record, only behind 2005 and 1950 in terms of named storms, hurricanes, and major hurricanes. With the continued strengthening of the La Niña event from 2016, activity was even higher than the previous season. The season was responsible for 26 depressions, of which 22 became named storms, 13 became hurricanes, and a record-tying eight became major hurricanes - a number not seen since 1950. Most tropical cyclones had devastating effects on land, with the southeastern continental United States and Caribbean taking devastating hits from many of the historic storms.

May & June
The season started nearly a month earlier than the official start date of June 1, with the formation of Tropical Depression One, later Hurricane Arlene, on May 12. Arlene made landfall on the Turks and Caicos in its weakening phase on May 15 as a strong tropical storm, later making landfall in southern Florida, causing minimal damage. The second pre-season storm developed weeks later on May 24, with this storm becoming Tropical Storm Bret a day later. Bret stayed out to sea during its lifetime, having caused no damage or fatalities.

June got off to an active start, much like in 2016, with the formation of a system that later became Hurricane Cindy, the first major hurricane of the season and the most intense tropical cyclone to form in June, with a minimum pressure of 952 mbar. Cindy took a track similar to Arlene less than a month earlier, causing severe damage in Turks & Caicos as well as the Bahamas as a major hurricane, with landfall in Miami, Florida as a Category 1 storm. Cindy became extratropical over the Gulf of Mexico and then made landfall in New Orleans as a regenerated subtropical storm with 60 MPH winds, causing minimal damage. Tropical Depression Four developed later in the month off the coast of South Carolina and traveling offshore the Eastern United States, bringing rain showers and flash flooding.

July & August
Tropical Storm Don formed on July 1 east of Barbados and later made landfall there as a tropical depression, bringing heavy rain showers and thunderstorms that persisted for an entire day. The system later strengthened into Don over the Caribbean, peaking at 50 MPH prior to weakening back down to a depression and hitting Nicaragua. On July 19, an extratropical system merged with a tropical wave which later gave way to Hurricane Emily, a powerful Category 4 hurricane, which later became the most intense Atlantic hurricane to form before August, ironically, breaking the record set by Hurricane Emily of 2005, which peaked as a Category 5 hurricane with minimum pressure of 929 mbar. Hurricane Emily of 2017, however, while a Category 4, hit a minimum pressure of 921 mbar at peak, going on to cause damage in Puerto Rico and South Carolina as a strong Category 4 hurricane, becoming the first hurricane to landfall in the state since Hurricane Hugo of 1989. A tropical wave developed into what would become Hurricane Franklin developed a day later, peaking as a 90 MPH Category 1 hurricane that would cause massive damage across Cape Verde, with the last storm to do that being Hurricane Fred of 2015. Franklin would later weaken to a tropical storm as it tracked northwest across the Northern Atlantic, making landfall in Bermuda as a 60 MPH tropical storm.

August became one of the most active months of the season with a total of seven storms forming during the month. Tropical Storm Gert developed from an extratropical low off the coast of South Carolina and tracked northeast for a period of two days as a weak tropical storm prior to making landfall in Newfoundland as an extratropical system. Hurricane Harvey developed on August 6 as a tropical storm near Cape Verde, eventually becoming a Category 4 major hurricane prior to making landfall in North Carolina as a high-end Category 2, causing widespread damage. Tropical Storm Irma developed three days later in the Gulf of Mexico, eventually making landfall in Port Arthur, Texas, resulting in a temporary shutdown of the oil refineries; however, these were re-opened shortly afterwards as damages were not as bad as initially anticipated. Hurricane Jose formed from an extratropical storm/tropical wave merger in the Caribbean on August 13, eventually making landfall in Cuba as a 70 MPH tropical storm, causing significant damage comparable to Dennis of 2005. Jose later strengthened to an 85 MPH Category 1 hurricane in the Gulf of Mexico, making landfall in Morgan City, Louisiana at that intensity, with damages amounting to nearly $700 million due to a large wind field and storm surge. Hurricane Katia was a powerful and long-lived Category 4 hurricane that formed from a Cape Verde tropical wave, eventually making an indirect hit on the Lesser Antilles and Puerto Rico as a Category 2 hurricane, which was still recovering from Hurricane Emily's hit earlier in the season. Katia then strengthened to Category 4 north of Turks & Caicos, followed by landfall in Bermuda at that intensity, which was still trying to rebuild from a direct hit from Category 5 Hurricane Hermine in the previous season. Katia later weakened to a Category 2 as the storm continued to track northward into Nova Scotia as a Category 2 hurricane, becoming one of the most damaging storms to make landfall there since Juan of 2003. Tropical Depression Thirteen brought torrential rainfall to the Azores on August 20, becoming the most northward depression of the season to form tropical, having lasted for less than a day, with the total time spent tropical being six hours, thus making it the shortest-lived tropical cyclone in the world. Hurricane Lee was also a powerful Category 4 fish storm that remained at sea for the majority of its life. At peak intensity, its minimum pressure was 912 mbar, making it the strongest storm of the season (at that point in time), as well as the strongest Category 4 hurricane in the Atlantic, surpassing Hurricane Opal's record of 916 mbar. Tropical Storm Maria formed near Cape Verde on August 31, seven days following the development of Hurricane Lee. Strong shear produced by Lee caused Maria to weaken and rapidly dissipate only a day later 45 miles WNW of Cape Verde.

September & October
September was the peak of activity during 2017, with the development of the first Category 5 of the season, Hurricane Nate, on September 6. Nate would peak at 165 MPH over the Central Atlantic, followed by landfalls in the British Virgin Islands and Puerto Rico as an upper-end Category 4 hurricane. Nate continued to track WNW, causing severe damage across Turks & Caicos as well as the Bahamas at C4 strength, followed by landfall in Miami, Florida as a Category 3 hurricane. Nate later emerged over the Gulf of Mexico as a tropical storm, taking a sharp turn north with a final landfall in Pensacola, Florida. After Nate's dissipation, it had left nearly $67 billion in damages, becoming the third costliest hurricane in Atlantic history (later fourth). The next storm to develop would also reach Category 5 status - Hurricane Ophelia. Ophelia would cause indirect effects on both Bermuda and the United States as the storm took a track similar to 2016's Hermine, but with no landfalls at hurricane intensity. Nova Scotia received a direct hit from Extratropical Storm Ophelia, causing widespread power outages and flooding across the region. Tropical Depression Eighteen developed on September 15 north of Venezuela and persisted for two days prior to dissipating 70 miles east of Nicaragua. A day later, Tropical Storm Philippe formed east of Bermuda and traveled east across the Northern Atlantic, passing to the north of the Azores, which received strong swells and rip currents from the storm. The extratropical remnants of Philippe caused minimal damage across Ireland and the UK, in addition to resulting in one death. On September 22, the strongest storm of the season, Hurricane Rina, formed, becoming the third and final Category 5 of the season, as well as being the final major hurricane of the season. Rina assisted in setting a record for the most Category 5 hurricanes to form in a month, with that number being three. Rina caused damage in the Bahamas and southern Florida as a Category 2 hurricane, followed by landfall in Galveston, Texas as a strong Category 4 hurricane shortly after reaching peak on September 29, becoming the second strongest landfalling hurricane in Texas history, only behind the 1900 Galveston hurricane, with Rina making landfall with a minimum pressure of 901 mbar, only one short behind the Galveston storm. Rina also became the second most intense hurricane to landfall in the United States at such an intensity, pushing Camille of 1969 and Katrina of 2005 to third and fourth places, respectively. Rina also became the 2nd costliest hurricane in Atlantic history, with total damages estimated to be $82 billion, only behind Katrina of 2005. Finally, Rina also became the costliest hurricane in Texas history, with fourteen counties being declared Federal Disaster Areas. Tropical Depression Twenty-One formed from an extratropical low off the coast of South Carolina and remained offshore from the Eastern United States as it later tracked into New Brunswick as a weak extratropical system.

October was significantly less active than the previous month, with only three storms forming during the month. Hurricane Sean was a low-end Category 2 hurricane that peaked over the Central Atlantic, with the extratropical remnants of the storm dropping torrential rain in Puerto Rico and Hispaniola, triggering massive mudslides and a widespread flooding event that caused more damage and fatalities than 2015's Tropical Storm Erika. Tropical Storm Tammy was a weak tropical storm that formed 123 miles northwest of Morocco, failing to develop due to increasing wind shear. Tammy had no effects on land whatsoever. Tropical Storm Vince developed from an upper-level low east of Barbados, with the precursor dropping torrential rain on the island. The system later became a subtropical depression over the Caribbean, later intensifying into a 50 MPH tropical storm on October 31. Vince later dissipated on November 5 after landfall in Cancún, where damage from the storm was virtually non-existent.

November & December
Hurricane Whitney was the only other "W" name to be used in the Atlantic basin, with the other being "Wilma", which was retired at the conclusion of the 2005 season, with Whitney being the replacement. Whitney peaked as an 85 MPH Category 1 hurricane in the Gulf of Mexico, with landfall at that strength in Cedar Key, Florida, causing moderate damage across the central part of the state with high winds and torrential rain. No other storms developed during the month of November.

December remained quiet until the end of the month, with the formation of a tropical wave that later became known as Tropical Storm Alpha, making 2017 the only other season in which the main list of names were exhausted and the Greek alphabet had to be utilized, with the first season being 2005. Tropical Storm Alpha slowly tracked across the Central Atlantic, with no landfalls during its life. Alpha persisted into January of 2018, making 2017 a rare season in which a storm persisted for two consecutive years, with others being 2005 (Tropical Storm Zeta) and 1955 (Hurricane Alice).

Hurricane Arlene
On May 11, a non-tropical area of low-pressure slowly began to attain tropical characteristics as it separated from its frontal boundaries while beginning to push west. Within several hours, the mid and upper-levels of circulation became much more well-defined as its feeder bands underwent an expansion phase, therefore slightly increasing the size of the system. By May 12, the National Hurricane Center (NHC) identified a closed circulation within system coupled with 35 MPH winds, resulting in an immediate upgrade to Tropical Depression One. One continued to drift westward at an extremely slow pace of 0.9 MPH, with a Tropical Storm Watch issued for Turks & Caicos as conditions remained favorable for further development. On May 13, One underwent explosive and rapid deepening as the pressure dropped to 991 mbar, from a high 1016 mbar, in addition to developing a well-defined core structure with rising cloud tops evident on sattelite imagery. Less than an hour later, winds exceeding 45 kt were found within the core after a barge reportedly drove through the storm, reporting intense conditions. Having heard this, the NHC operationally classified the storm as Tropical Storm Arlene. By May 14, Arlene reached its peak intensity of 70 MPH as it made landfall over the northern islands of Turks & Caicos. While not operationally classified as a hurricane, Arlene brought high winds and torrential rainfall to the islands, resulting in widespread electrical failure and uprooted power lines. Trees sustained heavy damage across the islands as gusts exceeding 75 MPH resulted in smaller ones being uprooted while larger ones lost multiple limbs, some of which fell on trees and dwellings, resulting in their absolute destruction. Arlene then underwent weakening as it passed west; bringing torrential rainfall to the Bahamas that persisted for hours. Heavy flooding occurred on three islands, with Paradise Island reporting a floodwater height, including storm surge, that sat at 4.7 feet. Power outages were also common across the islands as large tree limbs snapped and fell on lines, littering yards and public roads. Due to land interaction and minimal shelving prior to landfall, Arlene weakened to 45 MPH as it made landfall in Miami, Florida.

There was no significance of Arlene's Florida landfall as damages remained minimal and no fatalities were reported. However, intense rainfall totalling nearly twelve inches resulted in slick roads and saturated ground across the state, having caused nearly three dozen vehicle accidents, though no one died as a result of this. Trees sustained damage as continoully heavy rain brought tree branches down, sometimes crushing parked cars and houses. In the Everglades, the excessive rainfall caused the ponds within the wetlands to rise seven inches above normal, resulting in the terrain throughout the area to become extremely saturated, posing sinking hazards to both animals and humans alike. Moving across the southern end of the state, heavy rain inundated homes, with nearly 14% of homes in the state becoming uninhabitable, leaving nearly 620 residents homeless following Arlene. Damages still remained fairly lower than expected, amounting to only $3.4 million. Soon After, Arlene took a direct shift NNW over Tampa, with dry air entrainment resulting in an extratropical transition. Arlene rapidly degnerated thereafter, producing heavy rain across much of the Southeast United States as it traveled up the East Coast. Some minor tornadoes were produced in Geogia and the Carolinas, though none intensified past EF0. Damage, if any, was minimal and confined solely to trees. High winds brought some trees down onto Interstate 90 in Cleveland, Ohio, resulting in partial lane closures. The remnants of Arlene later dissipated over Nova Scotia on May 18.

Post-Analysis
While operationally classified as a severe tropical storm, in post-season analysis Arlene was found to be a minimal hurricane at peak, with winds of 75 MPH prior to landfall in Turks & Caicos, and damage across the islands much was found to be more severe then expected, at times being compared to the damage equivalent to a Category 1 hurricane. In the spring of 2016, the NHC officially classified Arlene as a Category 1 hurricane, thus upping its wind speed to 75 MPH. This marked Arlene as the first May hurricane and the most intense Atlantic tropical cyclone to form in May.

Tropical Storm Bret
Like Arlene, Bret developed from a non-tropical area of low-pressure drifting west across the Central Atlantic. High levels of wind shear and generally unfavorable conditions initially inhibited intensification, leaving the system a disorganized, slow-churning mess. However, the trough of wind shear the system was drifting through eventually dissipated on May 24. Soon thereafter, a gap wind event took place as the system underwent explosive deepening. Tropical Depression Two marked a rare occurrence in which the season had more then one pre-season storm to develop. The next day, Two developed strong inflow as large feeder bands began to form and wrap around the small yet unstable core of low pressure. The core continued to grow in size as its wind field began to expand, with the deepening core of low pressure resulting in an increase in wind speeds to 40 MPH, thus resulting in the storm being named Bret. Bret continued to track northwest over the next couple days as it underwent gradual weakening due to a large portion of ocean water east of Bermuda, where bret was tracking, remaining cool, despite decreasing levels of shear. By May 27, Bret's mid-level circulation began to dissipate as it slowly began unraveling, and its feeder bands separated from Bret and were absorbed by a frontal boundary, attaching itself to Bret's remnant area of low pressure. The following day, Bret's circulation was no longer visible on sattelite imagery nor radar, and any watches and warnings were discontinued. Because Bret never posed a threat to land, no damages or fatalities were reported.

Hurricane Cindy
At the beginning of June, the first tropical wave of the season began pushing west off the coast of Morocco. Bringing heavy rain and gusty winds to Cape Verde, the wave began pushing west while a centralized area of low pressure underwent the early stages of development around a warm core with unstable amounts of convection. Eventually, circulation began rapidly rotating around the central core, thus increasing the system's forward speed. Within the next several days, the system would go on to rapidly intensify, eventually becoming Tropical Storm Cindy 270 miles east of the Lesser Antilles on June 4.

Tropical Storm Don
Tropical Storm Don formed on July 1st as Tropical Depression 4 from a non-tropical low pressure system just east of the Barbados. The conditions in the area were largely unconducive to development, so forcasting agencies were not expecting Don to gain much intensity.