The 2017 Pacific typhoon season was a below-average season in terms of Accumulated Cyclone Energy and the number of typhoons and super typhoons, and the first since the 1977 season to not produce a Category 5-equivalent typhoon on the Saffir-Simpson scale. The season produced a total of 27 named storms, 11 typhoons, and only two super typhoons, making it an average season in terms of storm numbers. It was an event in the annual cycle of tropical cyclone formation, in which tropical cyclones form in the western Pacific Ocean. The season runs throughout 2017, though most tropical cyclones typically develop between May and October. The season's first named storm, Muifa, developed on April 25, while the season's last named storm, Tembin, dissipated on December 26. However, Tropical Storm Bolaven developed as a tropical depression on December 30 and persisted into 2018, when it strengthened to a tropical storm before dissipating on January 4. This season also featured the latest occurrence of the first typhoon of the year since 1998, with Noru reaching this intensity on July 23.
On January 7, the JMA began issuing advisories on a tropical depression located 400 km (250 mi) off Davao, Philippines. The JTWC issued a TCFA on the system around the same time, and began to issue advisories on the system as Tropical Depression 01W later that day after convection increased over the developing low level circulation, before they discontinued advisories after landfall the next day as the system weakened to a remnant low. The JMA continued to track the remnants of the system as a weak tropical depression, until the JTWC once again issued a TCFA on the redeveloping remains, before once again initiating advisories on the system as a tropical depression on January 15. The depression brushed the coast of vietnam, before dissipating again the next day as it lost its circulation. One death was reported relating to the storm in Vietnam, in relation to flooding caused by heavy rainfall.
On February 7, both PAGASA and the JMA initiated advisories on Tropical Depression Bising,which was located just inside the Philippines Area of Responsibility. The depression moved to the west, then north, before finally turning to the northeast, and dissipating out at sea on February 10, having had no impact on land whilst active.
On April 13, the JMA reported that a tropical depression had formed near Palau in the Federated States of Micronesia. Moving westwards into the Philippines area of responsibilty, it was named Crising by PAGASA, and on April 15, the JTWC issued a TCFA, and began to issue advisories on the system as Tropical Depression 02W. Late the following day, however, land interaction disrupted the circulation so much that it was declared a remnant low. Moving over the Philippines, the JMA and PAGASA continued to monitor the depression as it rounded the periphery of a subtropical ridge and moved towards Taiwan, dissipating to the west of the island as it was absorbed by a developing frontal system to its northeast. 10 people were reported to have died in relation to the flooding caused by the heavy rainfall associated with the storm.
During April 22, the JMA started to monitor a tropical depression that had developed near Guam. After moving westward for a couple of days, the JTWC began issuing advisories, and designated the storm 03W. By April 25, 03W organized and began consolidating further as the JMA upgraded the depression to a tropical storm, giving it the name Muifa. Muifa entered the Philippine Area of Responsibility the following day, and was named Dante by PAGASA. The storm, however, started moving northwards and immediately tracked out of the area by April 27. Following this, both the JMA and the JTWC downgraded Muifa to a tropical depression. Muifa dissipated early on April 29, and the JMA issued their final advisory on the storm.
On June 10, the JMA started to track a tropical depression to the west of Manila, Philippines. After the system entered a region favorable for further development, the depression rapidly organized, prompting the JTWC to start issuing advisories and give it the designation of 04W. A few hours later, 04W had intensified into a tropical storm, receiving the name Merbok as it starts to move in a north-northwestward direction. During June 12, Merbok reached its peak intensity with 10-minute winds of 100 km/h (65 mph) and a minimum pressure of 985 hPa, shortly before making landfall in Eastern Shenzen. On June 13, the JMA issued its final warning on Merbok, as the system dissipated over China.
Sustained winds of 95.0 km/h (59.0 mph) and a minimum pressure of 990.3 hPa (29.24 inHg) were recorded in Hong Kong as the eye passed nearby. Across Guangdong Province, 32 homes were destroyed, 122,000 people reported property damage, and 13,000 hectares of crops flooded. Total economic losses in South China were counted to be CN¥600 million (US$88.2 million).
On July 1, the JMA upgraded a low-pressure area it had been monitoring to a tropical depression, located south-southwest of Okinotorishima. Later that day, the JMA began issuing advisories once the depression's sustained winds were estimated at 55 km/h (35 mph). Shortly thereafter, the PAGASA classified the system as a tropical depression, assigning the local name Emong. On July 2, the JMA classified the system as a tropical storm, and assigned the official name Nanmadol. The JTWC followed suit and gave the internal designation of 05W. The cyclone continued to intensify, and was upgraded by the JMA to a severe tropical storm later that day. Nanmadol reached peak intensity at about 06:00 UTC on July 3, and maintained this strength until making landfall on the western coast of Kyushu several hours later. The cyclone began to accelerate while following a generally eastward course across the south of Japan. After brushing the southern coast of Japan, the JTWC issued its final advisory during the next day. The JMA followed suit late on July 4, when it had become extratropical. Its remnants moved out of the basin three days later.
Evacuation advisories were issued to at least 20,000 residents due to fears of possible flooding and landslides, especially in the prefectures of Niigata, Toyama and Nagano, which had experienced rainfall accumulations of up to 300 mm (12 in) in the preceding hours. At least three people were injured during the storm—a young boy's hand was injured when a school window broke in the city of Kumamoto, and two adults in Oita prefecture sustained minor injuries after falling due to the strong winds. A total of 41 people have been confirmed dead due to torrential rains which caused landslides and flooding, particularly in Kyushu. Total damages from the storm in Japan were amounted to be JP¥224 billion (US$2.04 billion).
Early on July 14, the JMA upgraded a low-pressure area in the South China Sea to a tropical depression after the system began to organize. Late the same day, the JMA began issuing advisories on the depression, and forecast it to develop into a tropical storm within the next 24 hours.
Talas made landfall near Vinh of Nghệ An Province in Central Vietnam at 01:00 ICT on July 17 (18:00 UTC on July 16) as a severe tropical storm. In Vietnam, the storm left 14 people dead and damaged around 2,700 houses. A coal ship with 13 crew members sank off the coast of Cửa Lò, leaving 3 dead and another 3 still unaccounted for. Damages in Vietnam were counted to be 1 trillion₫ (US$44 million). Total economic losses in Hainan Province reached CNY 60 million (US$8.9 million).
The JMA reported that a non-tropical low had transitioned into a tropical depression north-northwest of Wake Island early on July 19. Fluctuations in intensity occurred until late on July 29, when rapid intensification ensued. Total economic losses in Japan were counted to be US$100 million.
On July 20, the JMA started to monitor a tropical depression that formed over to the southwest of Midway Atoll, just to the west of the International Date Line. The JTWC classified the system as subtropical, however. By July 21, the subtropical storm started to show tropical characteristics, where it prompted both agencies to start issuing advisories, receiving the designation of 09W and the name Kulap. During the next day, Kulap briefly reached its peak intensity with 1-minute sustained winds of 95 km/h (60 mph) after imagery depicted some convection over near its compact center. After moving westward in a marginally favorable environment, the JMA had reported a minimum pressure of 1002 hPa with peak 10-minute winds of 75 km/h (45 mph) during the early hours of July 24. However several hours later, Kulap had entered in a very unfavorable environment such as cooler waters of 25 °C (77 °F). Due to strong shear and an interaction with Typhoon Noru to its south, Kulap had rapidly weakened; therefore, both agencies issued their final advisory on July 26. The JMA, however, tracked Kulap's remnants until July 28 when it was absorbed by the outflow of Typhoon Noru.
On July 21, both the JMA and the JTWC reported that Tropical Depression 08W had developed approximately 582 km (361 mi) to the south of Hong Kong. After moving westward for a couple of days, the system strengthened into a tropical storm by both agencies while nearing the island province of Hainan, receiving the name Sonca. By July 24, Sonca reached its maximum intensity with a minimum pressure of 994 hPa. Early on July 25, the JTWC issued its final advisory as the system made landfall over in Quảng Trị Province, Vietnam. The JMA issued its final advisory a few hours later when it had weakened into a tropical depression, although Sonca maintained its intensity over land until it had fully dissipated on July 29.
Flooding in Northern Cambodia drowned two people, blocked many roads and flooded several hundred houses. Damage across Sakon Nakhon, Thailand exceeded 100 million baht (US$3 million) and killed 23 people across Thailand.
The JMA noted the formation of a tropical depression southeast of Taiwan early on July 21. Assigning the numerical designation 10W, the JTWC upgraded the system to a tropical depression at about 18:00 UTC the same day. The system traveled in a generally northwesterly direction, and passed through the Luzon Strait, between Taiwan and the Philippines. Around the same time, the PAGASA began issuing advisories on the depression, and contributed the unofficial name Fabian. Early the next day, after the system had emerged into the South China Sea, both the JMA and the JTWC upgraded the system to a tropical storm, naming it Roke. Roke assumed a more westerly course, and tracked obliquely towards China's Guangdong coast. The JTWC downgraded the system to a tropical depression just 12 hours later, at 18:00 UTC, but the JMA maintained the cyclone's category as a tropical storm. Roke made landfall just east of the Hong Kong central business district at about 01:30 UTC on July 23, and passed over Shenzhen one to two hours later. Roke weakened to a depression a few hours later, though the JMA declared that it had dissipated on 18:00 UTC of the same day.
Schools, businesses and government offices were closed in Hong Kong as the Hong Kong Observatory (HKO) raised its typhoon warning signal to 8—the third highest of five levels—in preparation for Tropical Storm Roke. Ferry services in the city were suspended, and more than 50 flights were delayed. However, winds in the city were relatively light and no significant damage was reported.
The JMA upgraded a low-pressure area to a tropical depression east of the Philippines early on July 25.
Despite the storm not making landfall over in the Philippines, Nesat enhanced the southwest monsoon which brought torrential rainfall over most of the country. As of July 30, the NDRRMC had reported a total of Php 105.02 million (US$2.08 million) worth of damages. Total damages in Taiwan were counted to be NT$60 million(USD 2 million).Total damages in Mainland China were counted to be CNY 1.83 billion(USD 277.27 million).
A low-pressure area over the northern portion of the South China Sea was upgraded to a tropical depression by the JMA early on July 27. Despite an exposed LLCC with disorganized banding, the JTWC started initiating advisories, assigning the designation of 12W. During the next day, the system had strengthened into a tropical storm, with the JMA naming it as Haitang, after ASCAT image depicted 40 knot winds over in the southern portion of the storm. Due to the nearby Typhoon Nesat and moderate wind shear, Haitang maintained its intensity for several hours, until on July 30 when the system had deepened and reached its peak intensity with 10-minute sustained winds of 85 km/h (50 mph) with a minimum pressure of 985 hPa. Around the same time, Haitang entered the Philippine area of Responsibility, receiving the name Huaning by PAGASA, although the system had left the area during 12:00 UTC of the same day. Three hours later, the JTWC downgraded the system to a tropical depression, though it was re-upgraded into a tropical storm six hours later. By July 31, the JTWC issued their final advisory on Haitang after the system had made landfall over in the Pingtan County in Taiwan. During 06:00 UTC of that day, the JMA issued their final advisory after Haitang weakened into a remnant low.
During July 31, the JMA started to monitor a tropical depression located about 1,106 km (687 mi) to the northeast of Wake Island. During the next day, the JTWC started issuing advisories and designated it as 13W. By August 2, both agencies upgraded 13W to Tropical Storm Nalgae after imagery showed flaring convection and the storm was located in a region of low to moderate wind shear and warm SSTs. Moving in a northward direction, Nalgae slowly intensified for several days. Nalgae reached its peak intensity with 10-minute sustained winds of 85 km/h (55 mph) and a minimum barometric pressure of 988 hPa during August 5 for a brief time, as it was beginning to transition into an extratropical cyclone. The JTWC downgraded Nalgae to a tropical depression later that day and issued their final advisory after the storm was located in very unfavorable environments. The JMA followed suit early on August 6 when Nalgae fully transitioned into an extratropical cyclone, after which its remnants moved further north and were last noted during August 9.
On August 10, a tropical depression formed in the North Pacific Ocean. It strengthened into a typhoon on August 12, and reached its peak strength of 150 km/h (90 mph) on August 13. It weakened into a subtropical depression on August 17.
A low-pressure area developed into a tropical depression on August 19 while located to the southeast of Taiwan.
It gradually intensified and reached typhoon status on the afternoon of August 22 after entering the northeastern part of the South China Sea. On August 23, 07:00 HKT, Hato was approximately 100 km southeast of Hong Kong, bringing rain to the mainland as well as Hainan to the west. At 11:00 HKT the eye was approximately 60 km southwest of Hong Kong with the typhoon heading onto the mainland in a west-northwesterly direction.
Hong Kong Observatory issued Hurricane Signal No. 10 at 09:10 HKT, August 23, the first time since 2012. A total of 11 people were killed while total damages in Mainland China were counted to CN¥28.91 billion (US$4.38 billion). No people were killed in Hong Kong, while estimated damages in Hong Kong amounted to HK$8 billion (US$1.02 billion).In Macau, losses of 11.47 billion patacas (US$1.42 billion) were incurred when high tides exacerbated flooding in most of the lower lying areas, inundating ground floor shops and businesses. There were 12 deaths as a result of the typhoon including a number of people who drowned in flooded underground car-parks. Despite making landfall in South China, Hato triggered floods in Northern Vietnam and killed 1 person. The total damage by heavy rainfall in Bắc Kạn Province, were counted to be 25 billion₫ (US$1.12 million).
On August 26, Pakhar passed over the Philippines heading westward toward mainland China where it gathered strength before making landfall in Tianshan on August 27.
Total economic losses in South China have amounted to CN¥760 million (US$115 million) while a total of twelve people have been killed. Moreover, damages in the Philippines were recorded at PhP 41.27 million (US$808 thousand) and 2 billion ₫ (US$85,000) in Vietnam
On August 27, the JMA began to monitor a tropical depression that had developed about 441 km (274 mi) north-northeast of Saipan, although the system's nature was more of a monsoon depression. The JTWC followed suit on the following day, designating the system as 17W. Around the same time, the system had intensified into Tropical Storm Sanvu. By August 29, Sanvu increased in size, and therefore it prompted the JMA to upgrade it to a severe tropical storm. After moving in a westward direction, Sanvu stalled and entered a region of favorable conditions. As a ragged eye developed, both agencies upgraded Sanvu to a typhoon during August 31. Sanvu reached its peak intensity on September 1 as a Category 2 typhoon. Thereafter, the system steadily weakened as it started to move northwards with JTWC immediately downgrading the system to a tropical storm and issuing their final advisory late on September 2. The JMA still classified Sanvu as a typhoon until they issued their final advisory as the system had transitioned into an extratropical cyclone on September 3.
Sanvu did not caused any significant damage in the Mariana Islands, though a 33-year-old woman drowned at Obyan beach due to large waves on August 29.
On August 30, the JMA started to track a tropical depression to the north-northeast of Luzon, Philippines. Given the international designation of 18W by the JTWC, the JMA upgraded the system immediately to Tropical Storm Mawar. Slowly organizing, convection had rapidly developed and Mawar strengthened into a severe tropical storm early on September 2. On September 3, Mawar had weakened to a tropical storm after environments started to become unfavorable due to high wind shear. Later that day, Mawar weakened to a tropical depression and the JTWC issued their final advisory while making landfall over in Southeastern China between the cities of Shanwei and Shantou. The JMA followed suit early on September 4 when Mawar had fully dissipated.
The China's National Meteorological Center (NMC) issued a blue alert for the southern parts of Guangdong on September 1. During 2:00 a.m. local time on September 2, the Hong Kong Observatory issued a Tropical Cyclone Warning Signal No. 1 over in Hong Kong. Chinese authorities activated a natural disaster alert and response to help local civil affairs departments in areas such as the provinces of Fujian and Guandong to prepare for relief work. By September 3, the NMC had raised their warning signal to a yellow alert. Flooding from Mavar was a major concern with reports of rainfall of up to 80 mm (3.1 in) in some places which were impacted by Hato and Pakhar. Total economic losses in South China were counted to be CNY 10 million(USD 1.51 million).
On September 3, the JMA started to track a tropical depression that had developed to the east of Luzon, Philippines. During the next day, the PAGASA initiated advisories and gave the local name Kiko, while the JTWC followed suit by giving it the designation 19W. However, due to increased wind shear along with an exposed circulation, the JTWC issued its final advisory on 03:00 UTC September 5. Several hours later, deep convection was depicted and despite moderate to high shear, the JTWC re-initiated advisories, while the JMA had upgraded the system to a tropical storm, naming it as Guchol early on the next day. On 21:00 UTC of that day, the JTWC stopped issuing warnings on the system after convection significantly weakened. JMA later followed suit early in the next day by declaring it a remnant low as it neared Putian, Fujian on Strait of Taiwan. The remnant low would then make landfall over Pingtan County of Fujian in China late in the following day before it transitioned into an extratropical storm near Zhejiang as it merged with the cold front on September 8.
A tropical depression formed east of Guam on September 7. By the next day, the JTWC began issuing advisories on Tropical Depression 20W. On September 9, 20W organized into a tropical storm, with the JMA naming the system as Talim. With gradual intensification, the JMA upgraded Talim to a severe tropical storm. Talim further strengthened to a typhoon on September 11 where it simultaneously entered the PAR, with PAGASA naming it as Lannie. The JTWC, however, delayed their upgrade until September 12. Due to an ill-defined eye, Talim maintained its intensity until its eye became much clearer as rapid deepening ensued, as Talim became a Category 4 on September 14, and reached its peak intensity with 1-minute sustained winds of 220 km/h (140 mph). Talim began to curve eastward as it rapidly weakened to a tropical storm thereafter, making landfall in Kyushu on September 17, with a path of heavy rainfall up to the region east of Tokyo.
In total, 5 people were killed in Japan, and total damages were counted to be US$750 million.
As of September 19, the NDRRMC confirmed a total of 8 dead due to landslides and flooding while total damages were up to Ph₱267 million (US$5.23 million).
On September 15, Typhoon Doksuri made landfall in Quảng Bình Province, Vietnam as a Category 3 typhoon. Doksuri killed 15 people so far in Vietnam while estimated damages were about ₫16.36 trillion (US$720 million).Despite making landfall in Indochina, Doksuri affected Hainan and total economic losses were estimated to be CNY 100 million(USD 15.1 million)
A tropical depression formed to the west of Luzon on September 23, and was named "Nando" by PAGASA. The tropical depression quickly moved west-northwest and made landfall in Quảng Ninh, Vietnam, on September 25, before dissipating later on the same day. The China Observatory issued a "yellow" alert over in the eastern and southern regions due to rainstorms. Some areas have warned a possible precipitation of about 140 mm (5.5 in). Typhoon Signal No. 1 was raised over in Hong Kongduring September 24, with expected gusts of up to 70 km/h (42 mph) including rough swells. A voltage dip also occurred, causing 17 people to be trapped in lifts. As the depression approached Vietnam on September 25, the Vietnam National Center for Hydro-Meteorological Forecasting of Vietnam forecast rainfall of about 150 mm (5.9 in) in Hanoi and surrounding provinces, with rough waves up to 3 m (9.8 ft) in Ha Long Bay.
Early on October 7, a tropical depression formed to the west of the Philippines.
Early on October 10, the tropical depression made landfall in Hà Tĩnh Province, Vietnam, and dissipated shortly afterward. Consequently, both the JMA and the JTWC issued their final advisories for the storm.
Tropical Depression 23W caused severe flooding over provinces of Northern and Central Vietnam. Roughly more than 700 houses have been destroyed, while rescue efforts have saved 28 people from the danger zone. In total, 100 people were killed, and damages were about 13 trillion₫ (US$573 million). During October 10, the Red River was forecast to have waters exceed to the levels of 3–50 cm (2–20 in). In Hoàng Long river (Ninh Bình Province) flooding was the most severe since 1985.
According to the NDRRMC, Khanun killed only one person, with total damages of Php4.45 million (US$86,400).Authorities in Hong Kong and Macau raised the number 8 tropical cyclone warning on October 15 as gale-force winds affected the region. In total, damages from Khanun in South China were counted to be CNY2.46 billion (US$372.33 million).
The United States Naval Research Laboratory (NRL) initially mentioned a tropical disturbance over Chuuk on October 11. After the slow consolidation, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alertto the elongated system early on October 14, shortly after the Japan Meteorological Agency (JMA) started to monitor it as a low-pressure area. The agency upgraded it to a tropical depression almost one day later and began to issue tropical cyclone warnings since 06:00 UTC on October 15. In the afternoon, the JTWC also upgraded it to a tropical depression assigning the designation 25W, which formative but shallow convective bands had become more organized, and symmetrically wrapped into a defined low-level circulation center. About three hours later, the JMA upgraded it to the twenty-first Northwest Pacific tropical storm in 2017 and assigned the international name Lan, when it was located approximately 310 km (190 mi) to the northeast of Palau. Early on October 16, the JTWC upgraded Lan to a tropical storm too, based on T-number 2.5 of the Dvorak technique, shortly before it entered the Philippine Area of Responsibility and received the name Paolo from PAGASA. In total, 17 people were killed in Mainland Japan and total economic losses were counted to be US$2 billion.
Within the Northwest Pacific Ocean, both the Japan Meteorological Agency (JMA) and PAGASA assign names to tropical cyclones that develop in the Western Pacific, which can result in a tropical cyclone having two names. The Japan Meteorological Agency's RSMC Tokyo — Typhoon Center assigns international names to tropical cyclones on behalf of the World Meteorological Organization's Typhoon Committee, should they be judged to have 10-minute sustained windspeeds of 65 km/h (40 mph). PAGASA assigns names to tropical cyclones which move into or form as a tropical depression in their area of responsibility located between 135°E–115°E and between 5°N–25°N even if the cyclone has had an international name assigned to it. The names of significant tropical cyclones are retired, by both PAGASA and the Typhoon Committee. Should the list of names for the Philippine region be exhausted then names will be taken from an auxiliary list of which the first ten are published each season. Unused names are marked in gray.
During the season 27 tropical storms developed in the Western Pacific and each one was named by the JMA, when the system was judged to have 10-minute sustained windspeeds of 65 km/h (40 mph). The JMA selected the names from a list of 140 names, that had been developed by the 14 members nations and territories of the ESCAP/WMO Typhoon Committee. During the season, the names Hato and Lan were used for the first time, after they had replaced the names Washi and Vicente, which were retired after the 2011 and 2012 seasons, respectively.
After the season the Typhoon Committee retired the names Hato, Kai-tak and Tembin from the naming lists, while their replacement names will be announced in 2019.