Severe weather terminology (Japan)

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This article describes the Japan Meteorological Agency (JMA) severe weather terminology. The JMA defines precise meanings for nearly all its weather terms as the Information for Severe Weather Preparation ( 防災気象情報 , Bousai Kishō Jōhō). This article describes JMA terminology and related JMA weather scales. Some terms may be specific to certain regions.


Warning Categories

Severe weather bulletins are issued as an advisory or a warning, depending on the risk or severity of the event. Less severe events that could be a cause for concern will be issued as a bulletin or an advisory.

Meteorological Warnings

Weather advisories and warnings are issued when potentially hazardous weather is occurring or is forecast for the short-term period.

General Warnings

Due to its local-scale nature, an advisory is typically issued in advance for public forecast areas where conditions may be favorable for the development of severe weather. A warning is issued for areas where severe weather is imminent or occurring.



Marine Warnings 

Typhoons or Tropical Depressions 

Flood Forecasting

Seismological Warnings

Earthquake Information

Earthquake Early Warning

Tsunami Warnings

Volcano Information

See also

Notes and references

  1. "Emergency Warning System to be Launched 30 August 2013". Japan Meteorological Agency. 2013. Retrieved 3 August 2013.
  2. "JMA Brochure 2010" (PDF). Japan Meteorological Agency. 2010. Retrieved 31 March 2012.

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Japan Meteorological Agency National meteorological service of Japan

The Japan Meteorological Agency, abbreviated JMA, is an agency of the Ministry of Land, Infrastructure, Transport and Tourism. It is charged with gathering and providing results for the public in Japan that are obtained from data based on daily scientific observation and research into natural phenomena in the fields of meteorology, hydrology, seismology and volcanology, among other related scientific fields. Its headquarters is located in Minato, Tokyo.

Central Weather Bureau Meteorological service of the Republic of China (Taiwan)

The Central Weather Bureau is the government meteorological research and forecasting institution of the Republic of China (Taiwan). In addition to meteorology, the Central Weather Bureau also makes astronomical observations, reports on sea conditions, and conducts research into seismology and provides earthquake reports. The Central Weather Bureau is headquartered in Taipei City and is administered under the Ministry of Transportation and Communications.

In Japan, the Earthquake Early Warning (EEW) is a warning issued when an earthquake is detected by multiple seismometers. These warnings are primarily issued by the Japan Meteorological Agency (JMA), with guidance on how to react to them.

J-Alert Japanese disaster alert system

J-Alert is the early warning system used in Japan. J-Alert was launched in February 2007. The system is designed to quickly inform the public of threats and emergencies such as earthquakes, severe weather, and other dangers. The system was developed in the hope that early warnings would speed up evacuation times and help coordinate emergency response.

Tōkai earthquakes

The Tōkai earthquakes are major earthquakes that have occurred regularly with a return period of 100 to 150 years in the Tōkai region of Japan. The Tōkai segment has been struck by earthquakes in 1498, 1605, 1707, 1854, and 1923. Given the historic regularity of these earthquakes, Kiyoo Mogi in 1969 pointed out that another great shallow earthquake was possible in the "near future".

Typhoon Vongfong (2014) Pacific typhoon in 2014

Typhoon Vongfong, known in the Philippines as Typhoon Ompong, was the most intense tropical cyclone worldwide in 2014, and struck Japan as a large tropical system. It also indirectly affected the Philippines and Taiwan. Vongfong was the nineteenth named storm and the ninth typhoon of the 2014 Pacific typhoon season. Estimates assess damage from Vongfong to have been over US$160 million, mainly for striking mainland Japan. At least 9 people were killed along the path of the typhoon in those countries.

Typhoon Dujuan (2015) Pacific typhoon in 2015

Typhoon Dujuan, known in the Philippines as Typhoon Jenny, was the second most intense tropical cyclone of the Northwest Pacific Ocean in 2015 in terms of ten-minute maximum sustained winds, tied with Noul. The twenty-first named storm and the thirteenth typhoon of the 2015 Pacific typhoon season, Dujuan brought extremely powerful winds throughout the Yaeyama Islands and Taiwan in late September, causing 3 deaths in Taiwan. The typhoon also caused over ¥2.5 billion (US$392.9 million) damage in East China.

2016 Kumamoto earthquakes Earthquake in Japan

The 2016 Kumamoto earthquakes were a series of earthquakes, including a magnitude 7.0 main shock which struck at 01:25 JST on April 16, 2016 beneath Kumamoto City of Kumamoto Prefecture in Kyushu Region, Japan, at a depth of about 10 kilometres (6.2 mi), and a foreshock earthquake with a magnitude 6.2 at 21:26 JST (12:26 UTC) on April 14, 2016, at a depth of about 11 kilometres (6.8 mi).

Typhoon Megi (2016) Pacific typhoon in 2016

Typhoon Megi, known in the Philippines as Typhoon Helen, was a large and powerful tropical cyclone which affected Taiwan and eastern China in late September 2016. It is the seventeenth named storm and the seventh typhoon of the annual typhoon season.

Typhoon Nesat (2017)

Typhoon Nesat, known in the Philippines as Typhoon Gorio, was a strong tropical cyclone that impacted Taiwan and Fujian, China. It was the ninth named storm and the second typhoon of the annual typhoon season. After consolidating slowly for several days, Tropical Storm Nesat developed east of the Philippines on July 25. While experiencing favorable environmental conditions such as very warm sea surface temperatures and low Wind shear, Nesat strengthened into a typhoon and reached its peak intensity on July 28. On July 29, the typhoon made landfall near the Taiwanese city of Yilan, before weakening to a severe tropical storm and making landfall again near Fuqing on China's east coast late the same day. Moving into July 30, Nesat continued to weaken under the effects of land interaction.

Typhoon Trami Pacific typhoon in 2018

Typhoon Trami, known in the Philippines as Typhoon Paeng, was the second typhoon to affect Japan within a month. The twenty-fourth tropical storm and tenth typhoon of the annual typhoon season, Trami developed from a low-pressure area southeast of Guam on September 20. It intensified into a tropical storm on the next day, and intensified into a typhoon on September 22. Trami steadily intensified and reached its peak intensity late on September 24. On the following day, Trami slowed and drifted northward. It began to weaken due to upwelling. Trami accelerated and turned northeastward on September 29, before it struck Japan on the next day, and became extratropical on October 1. The extratropical remnants persisted for days until dissipated completely on October 8.

The 2019 Yamagata earthquake was an earthquake of magnitude 6.4 Mw which struck primarily the Hokuriku region in Japan on 18 June 2019 at 22:22 JST. The epicenter was close to the city of Tsuruoka, Yamagata. A tsunami warning was also issued.

Typhoon Francisco (2019) Pacific typhoon in 2019

Typhoon Francisco was a small tropical cyclone that impacted Japan and the Korean Peninsula in August 2019. Originating from a trough over the open Pacific Ocean on July 29, Francisco developed into a tropical depression on August 1. Tracking along a northwest course toward Japan, the system steadily intensified over the following days. It attained typhoon strength on August 5 and soon struck Kyushu at peak strength with winds of 130 km/h (80 mph). Thereafter, the weakened storm traversed the Korea Strait before striking South Korea on August 6. Turning toward the east, Francisco transitioned into an extratropical cyclone on August 7. It later impacted Hokkaido before continuing across the northern Pacific and dissipating.

Tropical Storm Ampil Pacific severe tropical storm in 2018

Severe Tropical Storm Ampil, known in the Philippines as Severe Tropical Storm Inday, was a tropical cyclone that caused moderate damage in the Ryukyu Islands and East and Northeast China in late July 2018. The tenth named storm of the annual typhoon season, Ampil developed into a tropical depression east of Luzon on July 17. The system gradually strengthened over the following days amid a marginally favorable environment and became a severe tropical storm late on July 19 as it moved northwest. Maintaining its strength, Ampil passed over Okinawa Island from July 20 to 21. Thereafter, Ampil weakened slightly while crossing the East China Sea, before making landfall in Shanghai, China, on July 22. The system weakened slowly over land and degraded to a tropical depression on July 23. The system turned eastwards as it continued weakening over land, diminishing to a remnant low on July 25 and dissipating fully a day later over the Russian Far East.

Typhoon Songda (2011) Pacific typhoon in 2011

Typhoon Songda, known in the Philippines as Typhoon Chedeng, was the strongest tropical cyclone worldwide in 2011, an exceptionally strong and catastrophic typhoon that lashed the eastern coast of the Philippines as a Category 5–equivalent super typhoon and affected the nearby Taiwan and Japan as a weakening tropical cyclone. The fourth tropical depression, second named storm and the first super typhoon of the 2011 Pacific typhoon season, Songda formed from a non-tropical low that was embedded from the Intertropical Convergence Zone on May 17. An area of low-pressure subsequently formed and became organized for the JTWC to issue a TCFA on the system and the JMA to issue advisories, before both agencies declared it a tropical storm, earning the name Songda. Under favorable conditions, Songda slowly intensified as it entered the Philippine Area of Responsibility, with the PAGASA naming it Chedeng on May 23. On the next day, the three agencies declared the system a typhoon before rapidly intensifying to a super typhoon over the Philippine Sea. As it entered an unfavorable environment for further strengthening, Songda slowly weakened as it passed near Taiwan, before becoming extratropical near Japan. The remnants of the system slowly moved to the northeast, before absorbing to another extratropical cyclone to the south of Alaska.

March 2021 Miyagi earthquake Earthquakes in Japan

On March 20, 2021 at 18:09 JST. The magnitude 6.9 or 7.0 earthquake struck offshore east of Tōhoku, Japan at a depth of 54.0 kilometers (33.6 mi) to 60 kilometers (37 mi). It had a maximum JMA intensity of Shindo 5+ while on the Mercalli intensity scale, it earned a rating of VII. Power outages and some slight damage in Miyagi was reported.

Tropical Storm Maliksi (2018) West Pacific Tropical storm in 2018

Severe Tropical Storm Maliksi, known in the Philippines as Severe Tropical Storm Domeng, was a tropical cyclone in June 2018 that brought rainfall to the Philippines and Japan. It caused 2 deaths and prompted the PAGASA to declare the beginning of the rainy season in the Philippines. The fifth named storm and 4th tropical cyclone in the Philippine Area of Responsibility (PAR), it was first noted as an area of convection on May 31.

Japan has a nationwide Tsunami Warning system. The system usually issues the warning minutes after an Earthquake Early Warning (EEW) is issued, should there be expected waves. The tsunami warning was issued within 3 minutes with the most serious rating on its warning scale during the 2011 Tōhoku earthquake and tsunami; it was rated as a "major tsunami", being at least 3 m (9.8 ft) high. An improved system was unveiled on March 7, 2013 following the 2011 disaster to better assess imminent tsunamis.

Typhoon In-fa Pacific typhoon in 2021

Typhoon In-fa, known in the Philippines as Typhoon Fabian, was a very large and costly tropical cyclone that brought record amounts of rainfall to China in July 2021, becoming the second-wettest tropical cyclone ever recorded in the country. It was also the first storm to impact the city of Shanghai since Typhoon Mitag of 2019. The ninth depression, sixth tropical storm and third typhoon of the 2021 Pacific typhoon season, the system was first noted by the Joint Typhoon Warning Center as an area of low pressure, located east of the Philippines on July 14. Favorable conditions helped the storm to intensify, becoming a tropical depression, two days later and a tropical storm on July 17, being assigned the name In-fa by the Japan Meteorological Agency. Located in a weak steering environment, the system struggled to organize under dry air and moderate wind shear before organizing further. It continued to move mostly westward, strengthening into a typhoon and deepening quickly. The storm struggled to organize itself significantly due to continuous dry air intrusions and its frequent motion changes. On July 21, it reached its peak intensity according to the JTWC with winds of 175 km/h (110 mph); the JMA estimated a lower numbers of 150 km/h (90 mph) on the system. Nevertheless, the system reached its minimum barometric pressure of 950 hPa (28.05 inHg), three days later after passing through the Ryukyu's. As the system entered the East China Sea, marginal conditions started to take toll on the system, with In-fa weakening steadily and slowly, until it made its consecutive landfalls over Putuo District of Zhoushan and Pinghu on July 25 and 26, respectively, as a tropical storm. For the next couple of days, the storm slowly moved inland while gradually weakening, before turning northward on July 29. Later that day, In-fa weakened into a remnant low over northern China. The remnants continued their northward trek for another couple of days, before dissipating near North Korea on July 31.

2022 Fukushima earthquake 2022 earthquake near Fukushima, Japan

On March 16, 2022, at 23:36 JST, a strong earthquake struck off the coast of Fukushima, Japan. The earthquake had a magnitude of 7.4 according to the Japanese Meteorological Agency (JMA), while the United States Geological Survey (USGS) gave a slightly lower estimate of 7.3. Immediately after the event a 30‑cm tsunami was reported. The event is known in Japanese as Fukushima-ken Oki Jishin. As a result of this natural disaster, four people died and 225 were injured.