Typhoon Roke, known in the Philippines as Tropical Storm Onyok, was a powerful and persistent
tropical cyclone
A tropical cyclone is a rapidly rotating storm system with a low-pressure area, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its locat ...
that affected
Japan
Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
, including some areas that had been damaged by
Talas just a few weeks prior. It was the fifteenth named storm, the tenth severe tropical storm, the sixth
typhoon
A typhoon is a tropical cyclone that develops between 180° and 100°E in the Northern Hemisphere and which produces sustained hurricane-force winds of at least . This region is referred to as the Northwestern Pacific Basin, accounting for a ...
of the
2011 Pacific typhoon season
The 2011 Pacific typhoon season was a below average season that produced a total of 21 named storms, 8 typhoons, and four super typhoons. This season was much more active than the 2010 Pacific typhoon season, previous season, although both seaso ...
and overall, the 27th tropical cyclone to be monitored by the
Japan Meteorological Agency
The Japan Meteorological Agency (JMA; ''気象庁, Kishō-chō'') is a division of the Ministry of Land, Infrastructure, Transport and Tourism dedicated to the Scientific, scientific observation and research of natural phenomena. Headquartered ...
during the year.
Meteorological history
On September 8, the Joint Typhoon Warning Center started to monitor a tropical disturbance that had developed about to the northeast of
Hagåtña, Guam
Hagåtña, formerly Agana or Agaña, is a coastal village and the capital of the United States territory of Guam. From the 18th through mid-20th century, it was Guam's population center, but today, it is the second smallest of the island's 19 ...
.
Unorganized deep convection was surrounding the disturbances developing low level circulation centre, in an area of low vertical windshear and improving outflow.
During that day the disturbance gradually developed further while moving westwards under the influence of a subtropical ridge of high pressure.
During September 9, as the system continued to move westwards, the
Japan Meteorological Agency
The Japan Meteorological Agency (JMA; ''気象庁, Kishō-chō'') is a division of the Ministry of Land, Infrastructure, Transport and Tourism dedicated to the Scientific, scientific observation and research of natural phenomena. Headquartered ...
reported that the disturbance had developed into a tropical depression.
Continuing to move westwards the system gradually developed further with the depressions low level circulation centre consolidating before it was declared Tropical Depression 18W by the Joint Typhoon Warning Center during the next day.
Over the next two days, the system gradually drifted west and intensified slightly, prompting the
Joint Typhoon Warning Center
The Joint Typhoon Warning Center (JTWC) is a joint United States Navy – United States Air Force command in Pearl Harbor, Hawaii. The JTWC is responsible for the issuing of tropical cyclone warnings in the North-West Pacific Ocean, South P ...
(JTWC) to issue a Tropical Cyclone Formation Alert (TCFA) on it. Convection gradually consolidated the low-level circulation center (LLCC) and the JTWC initiated advisories on the system on September 11, designating it with ''18W''. The next day, the depression drifted into the
Philippine Area of Responsibility
The Philippine Area of Responsibility (PAR) is an area in the Northwestern Pacific where PAGASA, the Philippines' national meteorological agency, monitors weather occurrences. Significant weather disturbances, specifically typhoons that enter o ...
(PAR) and the
(PAGASA) initiated advisories on the depression, naming it ''Onyok''. However, just as similar to Kulap, Onyok also exited the PAR in 6 hours from entering the region. In an advisory, the JTWC reported that there were at least two more
vortices
In fluid dynamics, a vortex (: vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in th ...
associated with the system, that caused an abrupt, erratic movement. However, being located in an area of warm
sea surface temperature
Sea surface temperature (or ocean surface temperature) is the ocean temperature, temperature of ocean water close to the surface. The exact meaning of ''surface'' varies in the literature and in practice. It is usually between and below the sea ...
s and low vertical wind shear, the depression continued to strengthen and on September 13, the JMA upgraded the depression to a tropical storm and named it ''Roke''.

On September 14, a
Tropical upper tropospheric trough
A tropical upper tropospheric trough (TUTT), also known as the mid-oceanic trough, is a trough situated in the upper-level (at about 200 hPa) tropics. Its formation is usually caused by the intrusion of energy and wind from the mid-latitudes into ...
(TUTT) cell located approximately 05 degrees to the west of the system caused strong
subsidence
Subsidence is a general term for downward vertical movement of the Earth's surface, which can be caused by both natural processes and human activities. Subsidence involves little or no horizontal movement, which distinguishes it from slope mov ...
prompting the JTWC to downgrade Roke to a tropical depression. However, because of favorable atmospheric conditions, Roke strengthened again, and the JTWC re-upgraded Roke to a tropical storm. On September 16, the previously exposed LLCC was being re-consolidated with convection and Roke continued to strengthen again. Despite the upper low over the LLCC, Roke remained a warm-core tropical cyclone and the JTWC predicted that there were chances of Roke become a hybrid or a
subtropical storm
A subtropical cyclone is a weather system that has some characteristics of both tropical and extratropical cyclones.
As early as the 1950s, meteorologists were uncertain whether they should be characterized as tropical or extratropical cyclones ...
. On continuing its west-northwestward movement, Roke eventually slowed to under with a tongue of cloud-free air entering the LLCC from the west side. Due to a mid-level warm anomaly, the subtropical transition was taking place at an unusually slow rate. Later, that day, Roke turned to the southwest and slowed with convection consolidating and deepening near the LLCC. What began as a monsoonal depression with an elongated and weak LLCC was now more stronger and organized. Also, the TUTT cell above the system started weakening and data from an ASCAT scatterometer pass revealed that the storm started to strengthen and the JTWC no longer expected a subtropical transition.
On September 17, the JTWC reported that Roke developed a small, deep convective eye with an unusually large convective band surrounding the southern periphery of the storm. At that time, Roke was approximately east of
Kadena Air Base
(International Air Transport Association airport code, IATA: DNA, International Civil Aviation Organization airport code, ICAO: RODN) is a United States Air Force base in the towns of Kadena, Okinawa, Kadena and Chatan, Okinawa, Chatan and the ...
,
Japan
Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
with winds of over . As a result, the JMA upgraded Roke to a severe tropical storm. However, Roke soon started become elongated around the northeast quadrant as a response to the strong
westerlies
The westerlies, anti-trades, or prevailing westerlies, are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes (about ...
ahead of a mid-latitude trough. But this was not for too long. Roke quickly became organized again and developed an excellent equatoward outflow and continued to strengthen. Then, being located in an area of low vertical wind shear and abnormally high sea surface temperatures, Roke underwent
rapid deepening
Rapid intensification (RI) is any process wherein a tropical cyclone strengthens very dramatically in a short period of time. Tropical cyclone forecasting agencies utilize differing thresholds for designating rapid intensification events, th ...
and became a Category 1 typhoon on the SSHS with a maximum sustained windspeed of (1-min sustained). The JTWC later reported that Roke underwent ''Explosive intensification'', a more extreme case of rapid deepening that involves a tropical cyclone deepening at a rate of at least 2.5
mbar
The bar is a metric unit of pressure defined as 100,000 Pa (100 kPa), though not part of the International System of Units (SI). A pressure of 1 bar is slightly less than the current average atmospheric pressure on Earth at sea ...
per hour for a minimum of 12 hours. Also, they added that Roke developed a eye and a good poleward
outflow
Outflow may refer to:
*Capital outflow, the capital leaving a particular economy
*Bipolar outflow, in astronomy, two continuous flows of gas from the poles of a star
* Outflow (hydrology), the discharge of a lake or other reservoir system
*Outflow ...
channel. On September 21, Typhoon Roke made landfall over
Hamamatsu
is a Cities of Japan, city located in western Shizuoka Prefecture, Japan. In September 2023, the city had an estimated population of 780,128 in 340,591 households, making it the prefecture's largest city, with a population density of over the t ...
, Japan at about 5:00 UTC (14:00
JST).
Soon Roke started weakening as cloud tops started getting warmed up and eye diameter started to decrease. However, the system still maintained a near radial outflow and the convective structure continued to remain organized that kept Roke from dissipating rapidly. Although Roke entered a de-intensification phase, it still had plenty of strength that posed a great threat to regions of Japan. Being located approximately southwest of
Yokosuka, Kanagawa
is a city in Kanagawa Prefecture, Japan.
, the city has a population of 373,797, and a population density of . The total area is . Yokosuka is the 11th-most populous city in the Greater Tokyo Area, and the 12th in the Kantō region. The city is ...
, the typhoon accelerated northeastward at approximately with winds of over (1-min sustained) being a Category 3 typhoon on the SSHS. Being embedded in the baroclinic zone, Roke started its
extratropical transition
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of p ...
. Also, land interaction severely weakened the storm to a minimal Category 1 typhoon with winds of under (1-min sustained). Only six hours later, the storm further weakened and accelerated northeastward at approximately with rapidly dissipating deep convection completely sheared to the northeast of the LLCC. As a result, the JTWC ceased advisories on the storm, as it became fully extratropical.
Preparations
Taiwan
On September 16, the
Central Weather Bureau
The Central Weather Administration (CWA; ) is the government meteorological research and forecasting institution of Taiwan (the Republic of China). In addition to meteorology, the Central Weather Administration also makes astronomical observation ...
, the government meteorological research and forecasting institution of the
Republic of China
Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...
(Taiwan) reported that the
outer bands of the storm might bring heavy rains to the northern part of the country over the next few days after slowly brushing the Japanese islands of
Okinawa
most commonly refers to:
* Okinawa Prefecture, Japan's southernmost prefecture
* Okinawa Island, the largest island of Okinawa Prefecture
* Okinawa Islands, an island group including Okinawa itself
* Okinawa (city), the second largest city in th ...
.
Japan

On September 16, the Japanese refiner company Nansei Sekiyu KK announced that they suspended marine operations for the rest of the week at its Nishihara refinery in
Okinawa Prefecture
is the southernmost and westernmost prefecture of Japan. It consists of three main island groups—the Okinawa Islands, the Sakishima Islands, and the Daitō Islands—spread across a maritime zone approximately 1,000 kilometers east to west an ...
that produces some as the storm neared land. Also, a
football
Football is a family of team sports that involve, to varying degrees, kick (football), kicking a football (ball), ball to score a goal (sports), goal. Unqualified, football (word), the word ''football'' generally means the form of football t ...
match was preponed by a day because of the storm's proximity to the island. The game was played during strong winds caused by Roke. On September 18, The national weather agency of Japan warned the residents of wide areas across the Japanese archipelago of heavy rainfall, landslides and flash flooding that the strengthening storm can trigger in Japan, after in changed course from heading towards the Okinawa Islands to mainland Japan. Also, concerns grew as the storm was heading towards the same area which was devastated by
Talas, an unusually large but weak tropical cyclone that hit the region just a few weeks ago. Parts of the
Kii Peninsula
The is the largest peninsula on the island of Honshū in Japan and is located within the Kansai region. It is named after the ancient Kii Province. The peninsula has long been a sacred place in Buddhism, Shinto, and Shugendo, and many people wou ...
which were still in ruins were in a great danger as water levels of the mud dam rose to 70 centimeters, just below its maximum capacity. It was feared that as the storm brushes the southern coast, it could worsen the conditions caused by Typhoon Talas. Hundreds of thousands of people in Japan were asked to evacuate their homes and move to safer places as Typhoon Roke neared southwestern Japan, on its way to hit the main island of
Honshu
, historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the list of islands by area, seventh-largest island in the world, and the list of islands by ...
with winds of over . It was reported that a further 23,000 people in western Japan were advised to seek shelter from flood and landslide prone areas. Over a million people, more than double the numbers for typhoon Talas, living in
Nagoya
is the largest city in the Chūbu region of Japan. It is the list of cities in Japan, fourth-most populous city in Japan, with a population of 2.3million in 2020, and the principal city of the Chūkyō metropolitan area, which is the List of ...
were also forced to evacuate. The typhoon was expected to batter the island nation for three continuous days, as it moved through the tsunami ravaged
Fukushima Prefecture
is a Prefectures of Japan, prefecture of Japan located in the Tōhoku region of Honshu. Fukushima Prefecture has a population of 1,771,100 () and has a geographic area of . Fukushima Prefecture borders Miyagi Prefecture and Yamagata Prefecture ...
. City officials in Nagoya upgraded the evacuation advisory to the strongest level available and doubled the number of people who are subjected to the notice as local rivers brimmed with heavy rain.
Impact
Japan
On approaching Japan, the typhoon instantly claimed four lives in central and western Japan, leaving two more missing in
Gifu Prefecture
is a Prefectures of Japan, prefecture of Japan located in the Chūbu region of Honshu. Gifu Prefecture has a population of 1,910,511 () and has a geographic area of . Gifu Prefecture borders Toyama Prefecture to the north; Ishikawa Prefecture ...
following widespread flooding triggered by the heavy rains. A large number of expressways were closed and up-to 200 flights were cancelled after floodwater reached knee-level.
Toyota Motor Corp
is a Japanese Multinational corporation, multinational Automotive industry, automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on August 28, 1937. Toyota is the List of manuf ...
, a
multinational automaker
The automotive industry comprises a wide range of companies and organizations involved in the design, development, manufacturing, marketing, selling, repairing, and modification of motor vehicles. It is one of the world's largest industries ...
headquartered in
Toyota City
, formerly known as Koromo, is a Cities of Japan, city in Aichi Prefecture, Japan. , the city had an estimated population of 426,162 and a population density of 464 people per km2. The total area was . It is located about 50 minutes from Nagoya ...
,
Aichi
is a prefecture of Japan located in the Chūbu region of Honshū. Aichi Prefecture has a population of 7,461,111 () and a geographic area of with a population density of . Aichi Prefecture borders Mie Prefecture to the west, Gifu Prefecture ...
, Japan, shut down 11 factories in central Japan eliminating evening shifts due to the typhoon. The
Chief Cabinet Secretary Osamu Fujimura
is a former Japanese politician of the Democratic Party of Japan, who served as Chief Cabinet Secretary under Prime Minister Yoshihiko Noda from 2011 to 2012. He was a member of the House of Representatives from 1993 to 2012.
Early life and c ...
said, "We need to exercise the maximum caution against heavy rain, strong winds and high waves in wide areas from western to northern Japan, according to the Meteorological agency". Soon, the strong winds and heavy rains cut power to more than 575,500 households in
Tokyo Electric Power Company
is a Japanese electric utility holding company servicing Japan's Kantō region, Yamanashi Prefecture, and the eastern portion of Shizuoka Prefecture. This area includes Tokyo. Its headquarters are located in Uchisaiwaicho, Chiyoda, Tokyo, an ...
's service area. Also, commuter trains were halted and thousands of passengers were stranded though they tried to go home early before the storm hit
Tokyo
Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...
. Later on September 21, local police and media reported that thirteen people were dead after being swept away by overflowing rivers. Unlike Talas, Roke moved significantly fast both inland and over the ocean. However, it was also unusually stronger. Also, the
Nissan Motor Company
is a Japanese multinational automobile manufacturer headquartered in Yokohama, Kanagawa, Japan. The company sells its vehicles under the ''Nissan'' and ''Infiniti'' brands, and formerly the ''Datsun'' brand, with in-house performance tuning pr ...
's spokesman Chris Keeffe said "workers at its Yokohama headquarters and nearby technical facilities were being told to go home early for safety reasons, and two plants were not operating."
Typhoon Roke caused no immediate problems other than broken security cameras at the Fukushima Dai-ichi nuclear power plant, which had been in its path overnight. The plant had been sent into meltdown by the March 11 earthquake and tsunami, and efforts are still under way to bring the reactors under control.
Other areas
The extratropical remnants of Typhoon Roke hit parts of
Russia
Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
,
Alaska
Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...
and
Canada
Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
. Heavy rain fell in the
Alaska Panhandle
Southeast Alaska, often abbreviated to southeast or southeastern, and sometimes called the Alaska(n) panhandle, is the southeastern portion of the U.S. state of Alaska, bordered to the east and north by the northern half of the Canadian provi ...
and
British Columbia
British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...
.
See also
*
Other tropical cyclones named Roke
*
Tropical Storm Talas (2011)
Severe Tropical Storm Talas (formerly called Typhoon Talas), was an unusually large tropical cyclone that caused severe damage and deadliest typhoon to hit Japan since Typhoon Etau in 2009. It was the 12th named storm and the 7th severe tropica ...
*
Typhoon Wipha (2013)
Typhoon Wipha, known in the Philippines as Typhoon Tino, was a large tropical cyclone, typhoon that caused extensive damage in Japan in mid-October 2013. The system originated from a tropical depression well to the east of Guam on October 8. ...
*
Typhoon Lionrock (2016)
*
Typhoon Noru (2017)
Typhoon Noru was the second-longest-lasting tropical cyclone of the Northwest Pacific Ocean on record—behind only 1986's Wayne and tied with 1972's Rita—and the second-most-intense tropical cyclone of the basin in 2017, tied with Talim an ...
References
External links
JMA General Informationof Typhoon Roke (1115) from Digital Typhoon
*The JMA'
Best Track Dataon Typhoon Roke (1115)
*The JMA'
RSMC Best Track Data (Graphics)on Typhoon Roke (1115)
*The JMA'
*The JTWC'
Best Track Dataon Typhoon 18W (Roke)
18W.ROKEfrom the U.S. Naval Research Laboratory
{{DEFAULTSORT:Roke (2011)
2011 Pacific typhoon season
2011 in Japan
2011 disasters in the Philippines
2011 in the Philippines
Typhoons in the Philippines
Roke
Roke is a hamlet in South Oxfordshire, about north of Wallingford. It has a sixteenth-century public house, the Home Sweet Home. It is now included in the neighbouring civil parish of Berrick Salome
Berrick Salome is a village and civil ...