2020 Pacific typhoon season

The 2020 Pacific typhoon season was the first with below-average tropical cyclone activity since 2001, with 23 named storms, 10 of which became typhoons and only 2 became super typhoons. This low activity was a consequence of La Niña that persisted from the summer of the year. It had the fifth-latest start in the basin on record, slightly behind 1973, and was the first to start that late since 2016. The first half of the season was unusually inactive, with only four systems, two named storms and one typhoon at the end of July. Additionally, the JTWC recorded no tropical cyclone development in the month of July, the first such occurrence since reliable records began. The season's first named tropical cyclone, Vongfong, developed on May 8, while the season's last named tropical cyclone, Krovanh, dissipated on December 24. However, the season's last system was an unnamed tropical depression which dissipated on December 29.

The scope of this article is limited to the Pacific Ocean to the north of the equator between 100°E and 180th meridian. Within the northwestern Pacific Ocean, there are two separate agencies that assign names to tropical cyclones which can often result in a cyclone having two names. The Japan Meteorological Agency (JMA) will name a tropical cyclone should it be judged to have 10-minute sustained wind speeds of at least anywhere in the basin, whilst the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) assigns names to tropical cyclones which move into or form as a tropical depression in their area of responsibility located between 135°E and 115°E and between 5°N–25°N regardless of whether or not a tropical cyclone has already been given a name by the JMA. Tropical depressions that are monitored by the United States' Joint Typhoon Warning Center (JTWC) are given a number with a "W" suffix.

__TOC__

Seasonal forecasts

During the year several national meteorological services and scientific agencies forecast how many tropical cyclones, tropical storms, and typhoons 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 University College London, PAGASA and Taiwan's Central Weather Bureau. The first forecast for the year was released by PAGASA on January 22 predicting the first half of 2020, within its monthly seasonal climate outlook. The PAGASA predicts that only 0–4 tropical cyclones are expected to form or enter the Philippine Area of Responsibility between January and March, while 5–8 tropical cyclones are expected to form between April and June. This was due to the fact that the El Niño–Southern Oscillation was seeing neutral conditions across the Pacific, and could persist until midyear. On May 21, the TSR issued their extended-range forecast for 2020, forecasting tropical activity below the average normal, with 26 tropical storms, 15 typhoons and 8 intense typhoons. These numbers were supported by the current values from the Indian Ocean Dipole, the Accumulated Cyclone Energy index and the sea-surface temperatures in the Niño 3.75 region, leading to a stronger than normal trade windspeed throughout much of the Western Pacific.

On June 24, the PAGASA issued a climate forecast, predicting the number of tropical cyclones for the second half of the season. They predicted that 6–10 tropical cyclones are expected to form between the months of July and September, while 4–7 tropical cyclones are expected to form between the months of October and December. On July 9, TSR issued their forecast for the season, predicting a well-below average season with 26 named storms, 14 typhoons and only 7 intense typhoons. On August 6, TSR issued their third and final forecast for the season, lowering their numbers to 21 named storms, 13 typhoons and 5 intense typhoons. They mentioned that the 2020 season is expected to be one of the "least active typhoon seasons on record", with a predicted ACE index barely half of the normal and a 96% probability of being a below-average season.

Season summary

The first few months of 2020 were inactive, with no tropical systems developing until May. On May 8, the season saw its first tropical system with the development of Tropical Depression 01W (Ambo), making it the sixth-latest starting season on record, as well as the latest since 2016. 2 days later, the system strengthened to the first officially named tropical storm of the season, Vongfong. Tropical Storm Vongfong then rapidly intensified into a significant typhoon and struck the central part of the Philippines on May 14, first making its landfall in San Policarpo, Eastern Samar, crossing 4 more islands and then hitting mainland Luzon.

After Vongfong, another month of inactivity ensued, and on June 10, a new tropical depression formed off the coast of Samar, Philippines, and was named Butchoy by the PAGASA a day later. Butchoy made landfall in the Philippines as the JTWC issued a TCFA for it. Once it exited Philippine landmass, Butchoy was upgraded into a tropical depression by the JTWC and all warnings issued by PAGASA were lifted, and Butchoy further intensified into a tropical storm in the South China Sea and was named Nuri by the Japan Meteorological Agency. After Nuri dissipated over mainland China, the basin became quiet again for more than a month with only Tropical Depression Carina forming east of Luzon; this led to the first time that no tropical storms developed within the month of July since reliable records began. The activity in the West Pacific increased somewhat with the formation of Tropical Storm Sinlaku, and the formation and intensification of Hagupit for a typhoon, ending a fast of more than 2 months without any significant typhoon. Hagupit affected China as a mid-Category 1-equivalent storm and caused US$441 million in damage. The storm then transitioned to an Extratropical cyclone and affected North Korea and Russia. A few days later, a new tropical depression formed, and then intensified into Tropical Storm Jangmi. Just southwest of Jangmi, a disorganized low-pressure area formed and would soon become Severe Tropical Storm Mekkhala, reaching China. A few days later, a new tropical depression formed in the South China Sea, and the PAGASA named the system as Helen. Shortly after, Helen intensified into a Severe Tropical Storm Higos, the 7th named storm on the 2020 typhoon season. Higos then went on to hit China. Soon after Higos dissipated, a new system formed in the east of the Philippines, and was named Igme. Igme then went on to become Tropical Storm Bavi and rapidly intensify in the coastal waters of Taiwan. In late August, Typhoon Maysak formed along
Super Typhoon Haishen, with the systems reached Korean Peninsula and Japan, respectively.

September started with Maysak weakening on its way to Korea, while a new Tropical Storm Haishen formed in the open Pacific, threatening the same areas that Maysak and previously Bavi affected. Typhoon Maysak made landfalls in South Korea and North Korea, while Typhoon Haishen intensified into the first super typhoon of the season. In mid-September, Tropical Storm Noul formed in the South China Sea, made landfall in Vietnam, and dissipated soon after. Later in the month, Tropical Storm Dolphin formed off the east coast of Japan and dissipated after a short life. Near the end of the month, Kujira formed and intensified into a severe tropical storm, before weakening and later becoming extratropical.

October was an extremely active month. The season started out with Typhoon Chan-hom, which lasted for 14 days before dissipating. On October 9, Tropical Storm Linfa formed, becoming the first of a train of tropical systems to affect Vietnam. Linfa killed more than 100 people and caused severe flooding in Vietnam and Cambodia. Nangka formed a few days after Linfa, though impacts were much less. A tropical depression, dubbed ''Ofel'' by the PAGASA went through the Philippines and then hit Vietnam, affecting the already flooded areas from Linfa.. After a short lull in systems, Typhoon Saudel formed on October 18, causing flooding in the Philippines. Afterwords, two very powerful typhoons formed after Saudel: Molave and Goni. The former killed 41 people throughout The Philippines, Vietnam, and Malaysia, while the latter became a Category 5-equivalent super typhoon. After Goni, Atsani formed and lashed Northern Luzon and Southern Taiwan as a tropical storm. As Atsani dissipates, another depression formed and affected Visayas as a depression, giving the name Tonyo. The next day, it was upgraded to a tropical storm, earning the name Etau. Etau lasted from November 7 until November 11. On November 8, a depression formed in the Philippine Area of Responsibility and was given the name Ulysses. The next day, it was upgraded to a tropical storm, giving the name Vamco. Vamco strengthened into an equivalent of a Category 2 typhoon as it brushed the Luzon landmass. It quickly exited the Philippine Area of Responsibility the next day as the PAGASA stated that it restrengthened as a typhoon. It rapidly strengthened and reached its peak intensity as a Category 4-equivalent typhoon. It weakened into a Category 1-equivalent typhoon as it approached Vietnam. It weakened further, finally, dissipated north of Laos. At last in the month of December, three systems formed with one named as Krovanh which formed at the South China Sea. Then the season concluded on December 29 with a weak depression close to the coast of Vietnam.

Systems

Typhoon Vongfong (Ambo)

A low-pressure area was first noted on May 9 by the JTWC near Micronesia and was given a medium chance of developing into a tropical cyclone. The following day, the JMA declared that it had developed into a tropical depression to the east of Mindanao, Philippines and was expected to slowly move west. The JTWC then issued a Tropical Cyclone Formation Alert (TCFA) for the system just hours later while convection began to gradually obscure the center. Later that day, the PAGASA followed suit and upgraded the system to a tropical depression, assigning it the name ''Ambo'', as it became the first tropical cyclone to enter their area of responsibility for 2020.

The system began to slowly drift westwards throughout the following days, and on the next day, the JTWC upgraded Ambo to a tropical depression, designating it as ''01W.'' The storm gradually intensified throughout the day and began to turn north. At this time, the JMA upgraded 01W to a tropical storm and assigned it the first name of the year, ''Vongfong''. Shortly after, the JTWC followed and upgraded the system to tropical storm intensity. Vongfong began to rapidly intensify due to favorable conditions by early May 13, With the JMA upgrading the system to a severe tropical storm and the JTWC upgrading the storm to a Category 1-equivalent typhoon with 1-minute sustained winds of as the structure quickly improved. The PAGASA and JMA would then upgrade the system to a typhoon later in the day, with the JTWC quickly upgrading the system to a Category 2-equivalent typhoon as the eye became clearer. A few hours later, Vongfong intensified to a Category 3-equivalent typhoon. Then, the storm later went an eyewall replacement cycle, quickly finishing the cycle while fluctuating in intensity. At 12:15 pm PST on May 14, Vongfong made its first landfall in San Policarpo, Eastern Samar. Vongfong gradually weakened shortly after, crossing over the Ticao Pass as it moved further inland. By the succeeding day, PAGASA recorded five more landfalls: hitting the islands of Dalupiri Island, Capul Island, Ticao Island, Burias Island, and San Andres, Quezon in Luzon Island's Bondoc Peninsula. Ambo weakened into a Category 1-equivalent typhoon following the landfalls. The system further weakened on May 15, and was downgraded by both the JMA and PAGASA to a severe tropical storm, with the JTWC downgrading it to a tropical storm as well. Vongfong made its seventh landfall on Real, Quezon, further weakening and being downgraded by the JMA and the PAGASA into a tropical storm. The weakening trend continued, and by May 16, Vongfong emerged into the Luzon Strait as a low-end tropical storm. 6 hours later, the JTWC downgraded Vongfong to a tropical depression, and issued their final warning. Soon after, PAGASA and the JMA followed suit as well. The remnants of the storm fully dissipated by May 17, with PAGASA downgrading the storm's remains into a low-pressure area.

In preparation for the incoming typhoon, Tropical Cyclone Wind Signal (TCWS) #3 warnings were issued for Northern Samar and the northern portion of Eastern Samar. According to the NDRRMC, Typhoon Vongfong (Ambo) left ₱1.57 billion (US$31.1 million) worth of damages in agriculture, and left 5 dead, as of May 27.
The international name Vongfong and Philippine name Ambo were retired from use by the Typhoon Committee and PAGASA, being replaced with ''Penha'' and ''Aghon'' respectively.

Tropical Storm Nuri (Butchoy)

On June 10, the JMA began monitoring on a weak tropical depression that had developed to the east of the Philippine island of Samar in Visayas. During the next day, the PAGASA began tracking the system, giving the local name ''Butchoy''. The storm then made its first landfall in Polillo Island in Quezon at 5:30 pm PHT, and making its second landfall in Infanta, Quezon shortly thereafter. Soon after, the JTWC issued a Tropical Cyclone Formation Alert for the storm. Afterwards, the JTWC officially upgraded Butchoy to a tropical depression, and designated it as 02W. With a favorable environment with low vertical wind shear, moderate equatorial outflow and 30–31 °C sea surface temperatures, Butchoy started to intensify in the South China Sea, becoming a tropical storm and receiving the name ''Nuri'' from the JMA later on the same day. Then, PAGASA issued their final warning on Nuri as it exited the Philippine Area of Responsibility. By the next day, Nuri intensified further and subsequently peaked in intensity, with the JMA analyzing the storm's peak winds of . Six hours later, the JTWC upgraded Nuri to a tropical storm. However, later in the same day, the JTWC downgraded Nuri into a tropical depression, citing that the storm has drifted into high vertical wind shear. The JMA followed suit, downgrading Nuri into a depression. The JTWC issued their final warning on Nuri as the storm subsequently made landfall in Yanjiang, China. The JMA followed suit six hours later, issuing their final warning on the system.

The PAGASA issued Tropical Cyclone Signal No. 1 for western Mindanao, southern Luzon, and Visayas on June 11 as Butchoy neared the Philippines. The combination of the system and prevailing southwesterly winds brought showers and thunderstorms across the Philippines. Heavy rainfall in Albay