Tropical Storm Etau (2009)
Encyclopedia
Tropical Storm Etau was the deadliest tropical cyclone
to impact Japan
since Typhoon Tokage in 2004. Forming on August 8 from an area of low pressure
, the system gradually intensified into a tropical storm. Tracking in a curved path around the edge of a subtropical
ridge
, Etau continued to intensify as it neared Japan. By August 11, the cyclone reached its peak intensity as a with winds of 75 km/h (45 mph 10-minute sustained) and a barometric pressure of 992 hPa (mbar). Shortly after, Etau began to weaken and was downgraded to a tropical storm early on August 11. Increasing wind shear
led to the center becoming devoid of convection
and the system eventually weakened to a tropical depression on August 13. The remnants of Etau persisted for nearly day before dissipating early on August 14.
Although Etau did not make landfall, the outer bands
of the storm produced torrential rainfall in Japan, peaking at 326.5 mm (12.9 in). These rains triggered deadly flooding and mudslides, especially in Hyōgo Prefecture
. Twenty-eight people were killed by the storm and ¥
7.1 billion (US$87.5 million) in damage occurred throughout the affected region. According to the Fire and Disaster Management Agency, a total of 5,602 homes were flooded and 183 were destroyed. Following the storm, 600 Japanese soldiers were deployed from Tokyo to assist in clean up efforts.
associated with disorganized convective
activity located about 550 km (280 mi) east-northeast of Guam
. The following day, the system relocated several dozen kilometers to the north. Convective turning began to appear on satellite imagery and a Tropical Upper Tropospheric Trough
(TUTT) cell to the north provided a northward component to the system's movement. Early on August 7, the Joint Typhoon Warning Center
(JTWC) issued a Tropical Cyclone Formation Alert
for the developing system as deep convection consolidated around the low pressure system. Around 0000 UTC on August 8, the Japan Meteorological Agency
(JMA) designated the system as a tropical depression.
Several hours later on August 8, the JTWC also declared the system a tropical depression, classifying it at 10W. Later that day, convection associated with the depression became disorganized, preventing intensification of the system. The depression generally tracked towards the northwest during the day in response a subtropical
ridge
to the north. By August 9, the center of circulation became more defined as convection wrapped around it. Around 1200 UTC, the JMA upgraded the depression to a tropical storm and gave it the name Etau. The JTWC, however, did not upgrade the system to a tropical storm for several more hours. On August 10, the JTWC briefly downgraded the storm to a tropical depression. By this time, the system had re-curved to the east around the western periphery of the subtropical ridge. Etau also became slightly disorganized as it began to interact with the baroclinic zone near Japan
. Early on August 11, the JMA reported that the storm winds had peaked at 75 km/h (45 mph 10-minute sustained) and a barometric pressure of 992 hPa (mbar). Later that day, the storm once more became slightly disorganized due to increased wind shear
; however, the JTWC reported that the storm intensified based on satellite intensity estimates and weather radar
imagery from Japan.
Later on August 11, the center of Etau became partially devoid of convection, with only a narrow band of shower and thunderstorm activity persisting to the southeast of the center. Increasing wind shear prevented convection from redeveloping and the storm continued to weaken. Early the following day, the JTWC issued their final advisory on Etau as they reported it had weakened to a tropical depression well to the east of Japan. Roughly 24 hours later, the JMA also downgraded the system to a tropical depression. The final advisory on Etau was issued by the JMA early on August 14 as it slowly tracked northward.
in Taiwan where at least 14 were killed in the country's worst flood in 50 years. Six flights in the country were canceled after a plane was struck by lightning
. Fifteen railway services were also canceled due to heavy rains. According to officials in Japan, nearly 140,000 people were evacuated to shelters in relation to flooding and landslides produced by Etau.
As Tropical Storm Etau brushed Japan on August 10, torrential rains fell within its outer bands
. In a 24 hour span, a record 326.5 mm (12.9 in) of rain fell, triggering extensive flooding and landslides. Initial reports stated that 13 people were killed and 10 others were missing due to the storm. Most of the fatalities took place in Hyōgo Prefecture where hundreds of homes were flooded and numerous others were damaged or destroyed by landslides. In some areas, flood waters reached a depth of 1.5 m (4.9 ft). One man drowned after driving his car into a flooded street and being overcome by the water. Another person was killed after her home was destroyed by a landslide in Okayama prefecture.
In Tokushima
, two people were listed as missing and two others sustained serious injuries. Later news reports stated that up to 18 people were missing following further landslides. The affected region was especially susceptible to landslides due to recent seismic activity, with a magnitude 6.4 earthquake
taking place on August 10. By August 11, one of the missing persons was confirmed to have been killed during the storm. About 800 people were placed in public shelters and 53,000 homes were left without running water. By August 12, a total of 18 people were confirmed to have been killed and nine others were still missing. Three bridges in Tokushima were also washed away. Days later, the Japanese Fire and Disaster Management Agency finalized the death toll at 26 with one other missing, making Etau the deadliest tropical cyclone to impact Hyōgo Prefecture
, Japan
since Typhoon Tokage in 2004. Throughout several prefectures, 5,602 homes were flooded and 183 were destroyed. Landslides triggered by the storm damaged another 2,109 structures, most of which were in Okayama
and Hyōgo prefectures. Following severe damages, in the town of Sayo it requested assistance from the national government
. As a result more than 200 troops were deployed to the town. A post-disaster office was also set up by the prime minister's office crisis management center. An additional 400 troops were deployed to the city by August 11 to assist in rescue efforts.
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
to impact Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
since Typhoon Tokage in 2004. Forming on August 8 from an area of low pressure
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
, the system gradually intensified into a tropical storm. Tracking in a curved path around the edge of a subtropical
Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone. As early as the 1950s, meteorologists were unclear whether they should be characterized as tropical or extratropical cyclones. They were officially recognized by the National...
ridge
Ridge (meteorology)
A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough....
, Etau continued to intensify as it neared Japan. By August 11, the cyclone reached its peak intensity as a with winds of 75 km/h (45 mph 10-minute sustained) and a barometric pressure of 992 hPa (mbar). Shortly after, Etau began to weaken and was downgraded to a tropical storm early on August 11. Increasing wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
led to the center becoming devoid of convection
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
and the system eventually weakened to a tropical depression on August 13. The remnants of Etau persisted for nearly day before dissipating early on August 14.
Although Etau did not make landfall, the outer bands
Rainband
A rainband is a cloud and precipitation structure associated with an area of rainfall which is significantly elongated. Rainbands can be stratiform or convective, and are generated by differences in temperature. When noted on weather radar imagery, this precipitation elongation is referred to as...
of the storm produced torrential rainfall in Japan, peaking at 326.5 mm (12.9 in). These rains triggered deadly flooding and mudslides, especially in Hyōgo Prefecture
Hyogo Prefecture
is a prefecture of Japan located in the Kansai region on Honshū island. The capital is Kobe.The prefecture's name was previously alternately spelled as Hiogo.- History :...
. Twenty-eight people were killed by the storm and ¥
Japanese yen
The is the official currency of Japan. It is the third most traded currency in the foreign exchange market after the United States dollar and the euro. It is also widely used as a reserve currency after the U.S. dollar, the euro and the pound sterling...
7.1 billion (US$87.5 million) in damage occurred throughout the affected region. According to the Fire and Disaster Management Agency, a total of 5,602 homes were flooded and 183 were destroyed. Following the storm, 600 Japanese soldiers were deployed from Tokyo to assist in clean up efforts.
Meteorological history
Tropical Storm Etau originated on August 5 out of an area of low pressureLow pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
associated with disorganized convective
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
activity located about 550 km (280 mi) east-northeast of Guam
Guam
Guam is an organized, unincorporated territory of the United States located in the western Pacific Ocean. It is one of five U.S. territories with an established civilian government. Guam is listed as one of 16 Non-Self-Governing Territories by the Special Committee on Decolonization of the United...
. The following day, the system relocated several dozen kilometers to the north. Convective turning began to appear on satellite imagery and a Tropical Upper Tropospheric Trough
Tropical Upper Tropospheric Trough
A tropical upper tropospheric trough , also known as the mid-oceanic trough, is a trough situated in upper-level tropics. Its formation is usually caused by the intrusion of energy and wind from the mid-latitudes into the tropics. It can also develop from the inverted trough adjacent to an upper...
(TUTT) cell to the north provided a northward component to the system's movement. Early on August 7, the Joint Typhoon Warning Center
Joint Typhoon Warning Center
The Joint Typhoon Warning Center is a joint United States Navy – United States Air Force task force located at the Naval Maritime Forecast Center in Pearl Harbor, Hawaii...
(JTWC) issued a Tropical Cyclone Formation Alert
Tropical Cyclone Formation Alert
A Tropical Cyclone Formation Alert is a bulletin released by the U.S. Navy-operated Joint Typhoon Warning Center in Honolulu, Hawaii or the Naval Maritime Forecast Center in Norfolk, Virginia, warning of the possibility of a tropical cyclone forming from a tropical disturbance that has been...
for the developing system as deep convection consolidated around the low pressure system. Around 0000 UTC on August 8, the Japan Meteorological Agency
Japan Meteorological Agency
The or JMA, is the Japanese government's weather service. Charged with gathering and reporting weather data and forecasts in Japan, it is a semi-autonomous part of the Ministry of Land, Infrastructure and Transport...
(JMA) designated the system as a tropical depression.
Several hours later on August 8, the JTWC also declared the system a tropical depression, classifying it at 10W. Later that day, convection associated with the depression became disorganized, preventing intensification of the system. The depression generally tracked towards the northwest during the day in response a subtropical
Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone. As early as the 1950s, meteorologists were unclear whether they should be characterized as tropical or extratropical cyclones. They were officially recognized by the National...
ridge
Ridge (meteorology)
A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough....
to the north. By August 9, the center of circulation became more defined as convection wrapped around it. Around 1200 UTC, the JMA upgraded the depression to a tropical storm and gave it the name Etau. The JTWC, however, did not upgrade the system to a tropical storm for several more hours. On August 10, the JTWC briefly downgraded the storm to a tropical depression. By this time, the system had re-curved to the east around the western periphery of the subtropical ridge. Etau also became slightly disorganized as it began to interact with the baroclinic zone near Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. Early on August 11, the JMA reported that the storm winds had peaked at 75 km/h (45 mph 10-minute sustained) and a barometric pressure of 992 hPa (mbar). Later that day, the storm once more became slightly disorganized due to increased wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
; however, the JTWC reported that the storm intensified based on satellite intensity estimates and weather radar
Weather radar
Weather radar, also called weather surveillance radar and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, estimate its type . Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the...
imagery from Japan.
Later on August 11, the center of Etau became partially devoid of convection, with only a narrow band of shower and thunderstorm activity persisting to the southeast of the center. Increasing wind shear prevented convection from redeveloping and the storm continued to weaken. Early the following day, the JTWC issued their final advisory on Etau as they reported it had weakened to a tropical depression well to the east of Japan. Roughly 24 hours later, the JMA also downgraded the system to a tropical depression. The final advisory on Etau was issued by the JMA early on August 14 as it slowly tracked northward.
Preparations, impact and aftermath
In anticipation of wind gusts up to 126 km/h (78.3 mph) and heavy rains, Japanese officials evacuated roughly 47,000 residents from western regions along the coast as gale warnings were declared by the JMA. Officials also feared that flooding from Tropical Storm Etau would mirror that of Typhoon MorakotTyphoon Morakot (2009)
Typhoon Morakot was the deadliest typhoon to impact Taiwan in recorded history. It formed early on August 2, 2009 as an unnamed tropical depression...
in Taiwan where at least 14 were killed in the country's worst flood in 50 years. Six flights in the country were canceled after a plane was struck by lightning
Lightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
. Fifteen railway services were also canceled due to heavy rains. According to officials in Japan, nearly 140,000 people were evacuated to shelters in relation to flooding and landslides produced by Etau.
As Tropical Storm Etau brushed Japan on August 10, torrential rains fell within its outer bands
Rainband
A rainband is a cloud and precipitation structure associated with an area of rainfall which is significantly elongated. Rainbands can be stratiform or convective, and are generated by differences in temperature. When noted on weather radar imagery, this precipitation elongation is referred to as...
. In a 24 hour span, a record 326.5 mm (12.9 in) of rain fell, triggering extensive flooding and landslides. Initial reports stated that 13 people were killed and 10 others were missing due to the storm. Most of the fatalities took place in Hyōgo Prefecture where hundreds of homes were flooded and numerous others were damaged or destroyed by landslides. In some areas, flood waters reached a depth of 1.5 m (4.9 ft). One man drowned after driving his car into a flooded street and being overcome by the water. Another person was killed after her home was destroyed by a landslide in Okayama prefecture.
In Tokushima
Tokushima, Tokushima
is the capital city of Tokushima Prefecture on Shikoku island in Japan.As of May 1, 2011, the city had an estimated population of 263,372, with 114,325 households, and a population density of 1,377.25 persons per km². Its total area is 191.23 km²....
, two people were listed as missing and two others sustained serious injuries. Later news reports stated that up to 18 people were missing following further landslides. The affected region was especially susceptible to landslides due to recent seismic activity, with a magnitude 6.4 earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
taking place on August 10. By August 11, one of the missing persons was confirmed to have been killed during the storm. About 800 people were placed in public shelters and 53,000 homes were left without running water. By August 12, a total of 18 people were confirmed to have been killed and nine others were still missing. Three bridges in Tokushima were also washed away. Days later, the Japanese Fire and Disaster Management Agency finalized the death toll at 26 with one other missing, making Etau the deadliest tropical cyclone to impact Hyōgo Prefecture
Hyogo Prefecture
is a prefecture of Japan located in the Kansai region on Honshū island. The capital is Kobe.The prefecture's name was previously alternately spelled as Hiogo.- History :...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
since Typhoon Tokage in 2004. Throughout several prefectures, 5,602 homes were flooded and 183 were destroyed. Landslides triggered by the storm damaged another 2,109 structures, most of which were in Okayama
Okayama Prefecture
is a prefecture of Japan located in the Chūgoku region on Honshū island. The capital is the city of Okayama.- History :During the Meiji Restoration, the area of Okayama Prefecture was known as Bitchū Province, Bizen Province and Mimasaka Province.- Geography :...
and Hyōgo prefectures. Following severe damages, in the town of Sayo it requested assistance from the national government
Government of Japan
The government of Japan is a constitutional monarchy where the power of the Emperor is very limited. As a ceremonial figurehead, he is defined by the 1947 constitution as "the symbol of the state and of the unity of the people". Power is held chiefly by the Prime Minister of Japan and other elected...
. As a result more than 200 troops were deployed to the town. A post-disaster office was also set up by the prime minister's office crisis management center. An additional 400 troops were deployed to the city by August 11 to assist in rescue efforts.
See also
- 2009 Pacific typhoon season2009 Pacific typhoon seasonThe 2009 Pacific typhoon season was the period that tropical cyclones formed in the Western Pacific Ocean. The season ran throughout the year during 2009, with most tropical cyclones forming between May and November. The scope of this article is limited to the Pacific Ocean, north of the equator...
- Timeline of the 2009 Pacific typhoon seasonTimeline of the 2009 Pacific typhoon seasonThis timeline documents all of the events of the 2009 Pacific typhoon season which was the period that tropical cyclones formed in the Western Pacific Ocean during 2009, with most of the tropical cyclones forming between May and November. The scope of this article is limited to the Pacific Ocean,...