Hurricane Leslie (2018)

Origins, formation, and tropical transition The United States-based National Hurricane Center (NHC) began forecasting on 19 September 2018 that an extratropical low would form in a few days between the Azores and Bermuda. This system developed along the boundary of a front early on 22 September, approximately west-southwest of Flores Island. This system was associated with the southern portion of the remnants of Hurricane Florence, which had previously split into two storms on 18 September. Amid favorable environmental conditions, the system separated from the front, and its banding features became better established, signaling the formation of Subtropical Storm Leslie by 12:00 UTC on 23 September. The subtropical cyclone was located within an area of minimal steering currents, causing the storm's movement to be erratic. Moderate vertical wind shear and dry air hindered the development of thunderstorm activity or convection outside the southeastern portion of the system, as it tracked generally southwestward. The cyclone turned towards the south and later the east on 24 September. During that time, Leslie's cloud pattern became irregular, with several cloud swirls existing within a broadening circulation. Leslie weakened into a subtropical depression around 00:00 UTC on 25 September, due to the continuing wind shear and dry air. followed by a turn back to the east. Leslie became an extratropical cyclone around 12:00 UTC, after its circulation expanded along a baroclinic zone. At that time, an expansive stratocumulus cloud shield was becoming established and cold, stable air was entering the region. During the next couple of days, Leslie's track consisted of an incomplete counterclockwise loop. At the same time, the baroclinic processes strengthened the extratropical cyclone, leading to hurricane-force winds of by 00:00 UTC on 27 September. A weakening trend commenced during the middle of the day and persisted until 28 September. However, as Leslie tracked westward, it began to reacquire tropical characteristics and was declared a subtropical storm once more around 12:00 UTC. Over the next couple of days, the cyclone experienced minimal change in strength as it tracked in a southwesterly direction around the western edge of an extensive cyclonic circulation. Initial peak intensity and weakening Located within a region of cool sea surface temperatures and strong northwesterly wind shear, the tropical storm intensified little during the next couple of days. Leslie continued a west-southwestward to southwestward motion over the next day or so, while located in weak steering currents and positioned between high-pressure systems that were located to the west and northeast. The storm intensified into a hurricane around 06:00 UTC on 3 October. Leslie reached its initial peak at 18:00 UTC as a Category 1 hurricane, with 1-minute maximum sustained winds of . Moving over cooler, sea surface temperatures, Leslie began to weaken slowly on 4 October. The cyclone weakened to a tropical storm around 18:00 UTC. Convection refired over the storm's center later that day, although the maximum winds were located away. Leslie turned towards the east from late 5 October to 6 October, under the influence of mid-latitude westerly flow. Although the tropical storm traversed a region of even colder, sea surface temperatures during the next couple of days and was located in a region of moderate wind shear, the storm changed little in strength. Leslie turned towards the east-southeast on 7 October, still under the influence of the westerly flow. Leslie bottomed out as an tropical storm at 00:00 UTC, as it passed over an area of cool sea surface temperatures. Peak intensity, extratropical transition, and demise Leslie began to restrengthen later on 8 October, as an inner core began to develop and convection became more intense. While the storm continued to track in a southeastward direction, traversing an environment of warmer sea surface temperatures and lower wind shear, a mid-level eye feature began to develop. Turning towards the south, Leslie restrengthened into a hurricane around 06:00 UTC on 10 October. The cyclone began to proceed east-northeastward early on 11 October, as strengthening continued. Leslie peaked at 00:00 UTC on 12 October as a Category 1 hurricane, with maximum sustained winds of and a minimum central pressure of , while located approximately south-southwest of Flores Island. Leslie began to slowly weaken once more later that day, as sea surface temperatures decreased to and wind shear increased. The mid-latitude westerly flow began to rapidly accelerate Leslie towards the east-northeast, with the cyclone passing north-northwest of Madeira Island around 06:00 UTC on 13 October. The cyclone's convection continued to disintegrate as a result of even colder sea surface temperatures and strong wind shear. The NHC issued its final advisory on Leslie around 21:00 UTC on 13 October, after the storm became fully extratropical. An almost stationary, convective cold front over southern France was assisted by Leslie. The latter helped to spawn a surface low over the Mediterranean Sea which increased convection near the cold front, and it provided unstable air parcels, reduced evaporation, and added moisture to the mid-levels of the airmass over France. Leslie's remnant was absorbed into Hurricane Michael's extratropical remnant by 16 October, following a brief Fujiwhara interaction. ==Preparations==

on 13 October|alt=Satellite image of Leslie approaching the Iberian Peninsula from an easterly direction on 13 October, while becoming a tropical-storm-force extratropical cyclone A tropical storm watch was issued for Madeira on 11 October, at 21:00 UTC. The watch was upgraded to a warning at 03:00 UTC on 12 October. Multiple flights were canceled on 12 October, and all flights were canceled on 13 October. In Funchal, all bathhouses and a park were closed. Sea voyages to Porto Santo were postponed and fishermen were ordered to move ashore by authorities. At least 13 districts in Portugal were placed under a red alert from 13 to 14 October, in anticipation of adverse weather conditions from Leslie. Alerts were also issued by Portugal for Madeira and the Azores. A 1990s-themed party at the Lisbon International Fair was moved back a week as Leslie approached. Fishing vessels were asked to return to port and surfers were ordered to move ashore. Seaside streets were closed between Parede and Carcavelos, as well as river routes in the Tagus between Trafaria, Porto Brandão and Belém were closed on 13 October, as Leslie approached Portugal. Nine ports in Portugal were closed to naval traffic due to the storm. Several shows and events in Lisbon, including the Lisbon Marathon, were either canceled or postponed. A yellow alert was declared for 25 provinces in Spain during the storm. An orange alert was issued for the provinces of Barcelona, Castellón, Huesca, Lleida, Navarra, Tarragona, Teruel, Zaragoza, Girona, and the Balearic Islands. In Seville, parks were closed on 13 October as a precaution, due to Leslie's approach. All parks but the Parque de Los Príncipes were reopened the next day, which was closed for repairs. The Aude, Hérault, Pyrénées-Orientales, Tarn, Haute-Garonne, and Aveyron departments in France were all placed under an orange alert, due to the expectation of strong winds and flooding rainfall from the approaching Leslie. ==Impact==

In November 2018, Aon estimated that Leslie's damage total exceeded €424 million (US$500 million). Portugal As the cyclone reached the Portuguese Coast, it brought wind gusts of ; Leslie was considered the worst cyclone to affect Portugal since 1842, until Storm Kristin made landfall in 2026. Buoys at three locations along the coast recorded the height of wind-generated waves. Around 00:00 UTC on 14 October, waves up to high were observed offshore Faro. Waves affected Leixões and Sines around 08:00 UTC, with peak wave heights of occurring there, respectively. Across Portugal, at least 441 structures collapsed due to strong winds. Thousands of trees were felled by the storm. A 150-year-old araucaria columnaris, a member of a tree species rare to Portugal, was among the trees felled. The storm left 324,000 customers without power and injured a few dozen people. At least 61 people had to be evacuated from their houses due to damage from the storm; 57 people were from Coimbra, 3 from Viseu, and 1 from Leiria. The storm caused significant damage to the forest industry in Portugal. Over 1,000 vehicles were damaged across the country. Damage from Leslie in Portugal was estimated to be around €120 million (US$145 million), with half of the total stemming from 28,000 insurance claims for storm damage. Wind gusts of downed trees and traffic signs, with the former causing several traffic accidents. In the city, six vehicles were damaged by a collapsing building, and another five were damaged by falling trees. Multiple homes in the area were deroofed. Near the shoreline, a car was pulverized and a restaurant was reduced to rubble. A high-voltage power pole collapsed in Leirosa, falling on a house; the roof of the house subsequently collapsed. A surf instruction center near Praia da Leirosa was lifted onto another property. Strong winds picked up a trailer and tossed it on top of another. At least 80 trailers were either damaged or destroyed in the park. Figueira da Foz was considered the worst-hit municipality, with the storm inflicting €38 million (US$46.2 million) in damage. At least 3,500 trees were downed near Serra da Boa Viagem alone. The core trees of the forest, which had survived two wildfires in 1993 and 2005 and a major storm in 2013, was largely destroyed. Falling trees smashed concrete picnic tables at a park. The roofs of four bungalows sustained damage, and the balcony cover and glass of another was shattered. The Casa do Parque suffered roof damage; six changing rooms experienced both internal and roof damage, and a dishwashing station was destroyed. Nearly 40 percent of the trees in the Choupal National Forest were either damaged or felled by Leslie. In Soure, damage was estimated to be at least €1,000,000 (US$1,208,000), with around €600,000 (US$725,000) in damage being to sports infrastructure alone. Schools in the town were closed due to damage and power outages. Around 90 percent of the homes in 8 parishes were damaged by Leslie. The storm broke tiles on several streets and knocked down trees. A pavilion was deroofed in the village of Simões. Municipal authorities dispensed generators to multiple towns in the Soure municipality. Equipment and greenhouses also sustained damage. The Equestrian Center of Montemor-o-Velho was almost entirely destroyed by the storm. The power company EDP declared a state of emergency in Coimbra, as a result of damage to electrical infrastructure. A number of high voltage power poles were either felled or bent by the storm. Scaffolding and signage were damaged across the municipality. National Road 1 was closed in two places between Mealhada and Coimbra due to fallen trees. In Senhor da Serra, solar panels used to power a school were damaged, which caused the school to close for a day. A sanctuary, a chapel, and seven greenhouses received roof damage. A sports field and over a dozen homes were also damaged. Leiria District In the Buçaco National Forest, Leslie left 60 people in the Palace Hotel and another 14 in houses cut off from the outside world for days. The roof of Maritime Police facility was lifted away, and the structure had multiple walls destroyed. A restaurant was destroyed at Praia do Pedrógão. Winds blew away tents at the Praia da Vieira, prompting the evacuation of 60 people. Damage in the municipality was estimated to be €5 million (US$6.1 million). Around 50 campers were evacuated in Alcobaça. The A17 highway connecting Leiria to Aveiro was closed due to fallen trees. A gas leak also occurred at a restaurant. Players took refuge in locker rooms. Shipyards and a pavilion were damaged in Mealhada municipality, and a cafeteria sustained damage in Alameda municipality. A blackout occurred in Porto on a street in Trofa after a street light toppled over. Other districts Leslie brought wind gusts of to the Madeira archipelago. A vault at the Convento da Saudação in Évora partially collapsed due to strong winds from Leslie. A 300-year-old ash tree near the Largo da Misericórdia sustained damage during the storm. One person was killed by a falling tree in Amieiro. At least 70 trees fell and 73 structures were damaged in Viseu municipality. Spain Leslie brought torrential rainfall and flooding to the autonomous communities of Andalusia, Catalonia, Castilla-La Mancha, the Balearic Islands, and Valencia. The storm caused at least 17 injuries across Spain. Heavy rainfall caused the Sió river to overflow in Catalonia. In Castilla y León, winds downed trees and branches on roads in dozens of locations. The R1, R2, and R11 lines of the Rodalies de Catalunya and five roads, including the C-17 highway in Barcelona, were closed as a result of fallen trees. Girona and Barcelona experienced 14,000 power outages and 12 roads were impassable due to floodwaters; the latter forced the suspension of school transportation services for six municipalities. A gas station roof was blown off in the Malgrat del Mar neighborhood in Barcelona. Six people had to be evacuated from surrounding properties when a building collapsed in Tortosa. Over of rain fell in Montseny, and of rain fell in Viladrau. Strong winds caused a wall to collapse in Santo Ángel, forcing the closure of a road. The Albujón highway was closed in Cartagena, due to the storm. A fair was canceled in Avenida de Los Toreros after a tree fell and roofs of two stalls were ripped off. The Toledo Cathedral sustained damage to its cornice, with a piece falling off. A tunnel flooded in Beniaján, trapping a vehicle. Several skates turned upside down in El Prat de Llobregat, and in Palomares, the masts of two skates were snapped and another was bent. Detritus plant matter and other dregs were swept onto the Sant Salvador beach by the storm, covering most of it. An Algerian Kilo-class submarine and its accompanying tugboat, Al Moussif, anchored in the Spanish-controlled Ares Estuary during the storm. An electrical cable snapped in Zamora, sparking a ditch fire and leaving 390 residences without power. A crane toppled over, striking a building in Soria. A 12-hour rainfall total of was reported in the town of Trèbes. Around 1,000 people were evacuated in the Pezens Municipality after a dam overflowed. In Veillardonnel and Conques-sue-Orbiel, floodwaters reached the height of first-floor windows. Police asked citizens in the Aude to remain in their houses and stay off flooded roadways. A total of 15 people were killed throughout the Aude as a result of the floods: six in Trèbes, three in Villegailhenc, two in Villalier, one in Veillardonnel, one in Carcassonne, and one in Saint-Couat-d'Aude. At least 75 additional people were injured in the department. Flooding interrupted railway traffic along the Béziers-Narbonne section and other routes in Carcassonne. Several roads in Carcassonne were blocked by felled trees, and cars were either swept away by floodwaters or destroyed. Schools and universities throughout the city were closed from 15 to 16 October. Multiple waterspouts occurred near the region bordering Spain. At least 700 municipalities experienced flood damage, with an estimated total of €220 million (US$254 million). Elsewhere The Alta, a freighter ship, experienced an unrepairable mechanical issue. The United States Coast Guard and the crew considered towing the ship, but ultimately abandoned it due to the nearby Hurricane Leslie. The ship ran ashore in Ireland on 16 February 2020. Météo-France issued a yellow alert for the overseas territory of Martinique on 3 October due to high surf generated by Leslie. The highest surf experienced in Martinique was in the Dominica Channel. From late September through early October, Leslie brought high surf to the East Coast of the United States, inducing the highest swell observed in some locations for years. Leslie also generated the single-longest period of tropical swells observed in the Outer Banks in the last 20 years, producing surf at chest height or higher. The highest surf was observed on 26–28 September, when Leslie was a powerful extratropical cyclone with hurricane-force winds. Leslie and a low-pressure system inhibited a trough from tracking eastward from 29 to 30 September, causing fog to persist for 32 hours in Ferryland, Newfoundland. ==Aftermath==

Portugal A marketplace was closed in Figueira da Foz due to roof damage, causing losses of €700 thousand (US$853 thousand) to local fishermen. Tree removal work began immediately after the storm; However, the Institute for the Conservation of Nature and Forests estimated that the removal work would take at least 6 months. Around 80 percent of the trees planted in pine forests along the coast of Leiria, in areas heavily affected by wildfires and Leslie, died. In order to aid the recovery of the forest, plantings would continue for multiple years. Roads were also to be improved as a part of the project, which had a financial backing of €18 million (US$21.9 million). Around €220,000 (US$268,000) were donated to fund the removal and sawing of felled trees in the Bussaco National Forest. Additional funds were donated to finance the planting of over 35,000 additional trees. Near the Palace Hotel, 100 trees were planted in an area damaged by Leslie in order to honor the life of Nelson Mandela. Despite being considered a public interest, the 300-year-old ash tree was cut down on 14 November 2019. Months after Leslie, students protested about the condition of the College of Arts building at the University of Coimbra, which was one of those damaged during the storm. In Chernache, the Aerodrome Bissaya Barreto was closed from 30 May–7 June 2019, due to additional problems after Leslie had removed its windsock. Around 10,000 personnel were mobilized to deal with fallen trees and landslides in Mira. Municipal authorities worked to clear fallen trees and repair broken walls and signage. The district emergency plan was activated for Coimbra district. The Portuguese government anticipated an expenditure of €36 million (US$43.8 million) would be required to aid the forest industry. Fisheries near Figueira da Foz operated at below normal capacity through 2020, due to a reduction in sardine supply that occurred after Leslie moved through the area. Although the Portuguese government agreed to cover 70 percent of the costs of reconstruction for the Equestrian Center of Montemor-o-Velho, it had not provided the funds two years post-storm. Initially, on 27 November 2018, the Portuguese government rejected a proposal to provide relief funds for victims of the storm. The government provided €1.4 million (US$1.7 million) out of a maximum of €8.3 million (US$10.1 million) in aid to 24 municipalities in 2019. They provided another €3.6 million (US$4.3 million) to those municipalities in 2020. The legislature allocated €20 million (US$24.3 million) in aid to the agricultural sector. The Portuguese government opened up €15 million (US$17.7 million) in relief funds for farmers who sustained damage to buildings, equipment, livestock, and permanent crops. At least seven companies received financial aid totalling €391,000 (US$478,000). Social organizations that experienced large financial woes had not received relief funding from the Portuguese government two years after the storm. The legislative body was criticised for being slow in authorising the release of funds to these organizations. The Coimbra City Council approved a measure on 30 June to repair the Celas Integrated Sports Center and a building at the Campo Municipal da Arregaça, both of which were severely damaged by Leslie. Despite repairs having taken place at the sports center, it remained closed nearly a year after Leslie passed through the region. In 2021, the Rural Development Program provided €98,000 (US$120,000) in aid to help repair damage caused in the Choupal National Forest. At least 5,000 new trees were to be planted and 700 damaged ones either cut down or trimmed. To aid recovery efforts, €5 million (US$6.1 million) in funds were approved for a recovery plan for the Leiria National Forest in the Marinha Grande Municipality. The plan included the planting of at least 230 trees to restore the forest after Leslie and a 2017 fire destroyed most of it. The Miranda do Corvo city council approved €74,850 (US$91,400) in funds to rebuild the Senhor da Serra Pavilion, which was entirely destroyed by the storm. The council also approved €34,085 (US$41,600) in aid to repair the headquarters for the Vale do Açor Recreational, Cultural and Sports Association. France After the storm, victims in the Aude proceeded to shelters or lodged with their neighbors, and schools were closed. Around 700 firefighters, 160 police officers, and rescue agencies took part in cleanup and rescue operations in the department. Seven helicopters and one plane were mobilized for search and rescue missions in the Aude. The French Insurance Federation recorded 35,000 claims of damage in regards to the floods caused by Leslie, with 27,000 of those occurring in the Aude. Collectively, €17 million (US$20 million) in advances were paid to claimants. ==See also==