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East Asian-western North Pacific storms/cyclones also known variously as (East Asia cyclones, East Asian maritime storms, East China Sea storms, East Asian winter storms, Spring storms (Japan), May storms (Japan) and Northwestern Pacific storms (too confusable with Pacific NW?)-http://journals.ametsoc.org/doi/abs/10.1175/1520-0493(1992)120%3C3029%3ACOECOT%3E2.0.CO%3B2 East Asia-West Pacific cyclones -http://www.iapjournals.ac.cn/aas/ch/reader/view_abstract.aspx?file_no=940301) are Extratropical cyclones which typically form in and have their greatest  frequencies around Japan in spring, Spring cyclones are most frequent and cause disastrous winds and widespread heavy rain episodes in Japan (Uemura 1981; Nishii et al. 2009).

form during the winter months of the year. Tropical typhoons and tropical storms are frequent in the region china taiwan and japan between July and September.

“This was a condition which is referred to as a ‘May Storm’ ” According to the JWA, such volatile conditions — where the stormy weather quickly builds up — is called a “bakudan” (bomb) low-pressure front. Bakudan teikiatsu (爆弾低気圧 literally “low pressure bomb”): A rapid drop in atmospheric pressure that precipitates a sudden and intense storm, applied to typhoons and extratropical winter storms in Japan.

cold, dry winter East Asian Monsoon, spring storm as warm subtropical air moves north and interacts with cold air outbreaks from the Siberian high continental asia

Main

 * http://tao.cgu.org.tw/pdf/v84p427.pdf

Cyclogenesis
In spring, while the growth rate of baroclinic eddies is smaller than that in winter, a cyclone frequency is greatest in March (Fig. 1). As the season progresses, the Pacific coastal track shifts northward off the east coast of Japan.

most rapid deepening tends to occur to the east of Japan south of 50˚N, in the vicinity of the Kuroshio Current.

Cyclogenesis occurring off the east coast of China and revealed that the strong north-south gradient of SST across the East China Sea played a significant role in winter cyclogenesis, surface baroclinicity associated with this temperature gradient is the dominant mechanism for cyclogenesis. Area of frequent bomb cyclogenesis.

the East Asian winter monsoon variability changes the baroclinicity, especially in the lower troposphere and the surface heat exchange between the Kuroshio Current and the Kuroshio Extension and the overlying atmosphere, playing an influential role in the concentration and the magnitude of the developing rate of explosive extratropical cyclones. http://www.sci.u-toyama.ac.jp/earth/e-kawamura/yoshiike_kawamura_JGR.pdf

''The relationships between large-scale wintertime circulation and extratropical cyclones that develop explosively (the so-called bomb cyclones) over the western North Pacific are investigated using Japanese long-term reanalysis project data. On a monthly basis, the East Asian winter monsoon variability strongly modulates the bomb cyclone activity in terms of its geographical distribution. When the monsoon is strong, the bomb cyclone activity tends to concentrate in the vicinity of the Kuroshio Current and the Kuroshio Extension near Japan, while when the monsoon is weak, it disperses over the broader areas. The enhancement of the monsoon increases the heat and moisture supply from warm currents, facilitating unstable conditions within the atmospheric boundary layer and intensifying baroclinicity in the lower troposphere. These factors are believed to play a role in inducing bomb cyclones, particularly along the warm currents. On submonthly timescales, the stationary Rossby wave propagation along the South Asian waveguide serves as a prominent trigger for the rapid reinforcement of synoptic-scale disturbances around Japan. When a pronounced bomb cyclone comes to its mature stage northeast of Japan, it is capable of exciting stationary Rossby waves downstream from the Asian jet exit region as vorticity forcing. The stationary wave packets developing southeastward across the North Pacific Ocean basin induce surface cyclogenesis in the vicinity of the Hawaiian Islands by leading to the equatorward advection of higher potential vorticity from the midlatitudes, bringing about the occurrence of kona storms, which cause weather hazards in Hawaii.''

western north pacific

Closest analogy to the Nor'easters of the North American continent, where cyclogenesis occurs above the Gulf stream, but also in Southern Hemisphere to the Australian east coast cyclones which form over the East Australian Current.

increase in bomb cyclogenesis between 1979 and 2011.

'''In the cold season, Japan is  located between the Siberian high  in the west  and the Aleutian  low  in the  east. This state holds  in  midwinter  and  is  often found in early and late winter, anti-correlated with seasonal variations in the storm track   activity   in   the   western   North   Pacific   (Nakamura   1992). Moreover, Nakamura et  al. (2002)  suggested  that the intensity of storm  activity  is  weak during winters with a strong Aleutian low pressure, and strong when the Aleutian low  pressure  is  weak. This seasonal and interannual variability  of  storm  activity has been comprehensively studied, and is well understood (Nakamura et al. 2004).''' Nakamura 2002 Arctic oscillation.

Tracks
In winter, cyclogenesis events over the Far East are concentrated into two areas: over the Sea of Japan, and from the East China Sea to the south of Japan (Chen et al. 1991).

As noted by Chen et al. (1991) and Asai et al. (1988), there are three cyclone tracks around Japan: (1) the Pacific coastal track, (2) the Japan Sea track (~40°N), and (3) the Asian continent track (~50°N). The latter two tracks are frequent in autumn and spring. The primary path of cyclones (grid with the largest frequencies along row direction of the EASE grid; see Supplement 1) is the Pacific coastal track, which starts from the southwestern tip of the Japanese Islands and extends northeastward to the western North Pacific in the vicinity of the Kuroshio Current and the Kuroshio Extension.

For heavy rain episodes, cyclone tracks in both the Asian continental and Pacific coastal tracks shift slightly northward compared with those of the moder- ate rain episodes. The Pacific coastal cyclone track starts from the East China Sea and crosses over western Japan, whereas that in moderate rain episodes is displaced southeastward to the primary climatological path. The cyclone center rarely crosses over Japan in the moderate rain episodes. The second characteristic is the traveling direction of the cyclones. The cyclones tend to move more poleward than the climatological path, which is located along oceanic frontal zone. Spatial distribution of the maximum developments of cyclones also shows differences between heavy and moderate rain episodes In the heavy rain episodes, the number of maximum developing cyclones increases over western Japan.

Two preferred routes of cyclone passage over Japan. One route through Northeast China, the Sea of Japan, and the ocean to the northeast of Japan, called Sea of Japan cyclones. Second route through Taiwan, the southern coast of Japan and the ocean to the southeast of Japan, called Nangan (southerly) cyclones.
 * Kuroshio/
 * Nangan/Sea of Japan cyclones

Kuroshio Current Tsushima Current

'''However, storm  track  frequency is  not  yet  well  understood. Hoskins and Hodges (2002) have constructeda global map of cyclone frequency by using their sophisticated  tracking  algorithm. In East  Asia,  two preferredroutes  toward  the western  North  Pacificwere  observed(Adachi  and  Kimura  2007),  andTakayabu (1991) and Inatsu (2009) discoveredtwo preferredroutes thatmerge tothe east of Japan. Thesemi-subjective weather  chart  analysisperformed  by Kusaka  and Kitahata (2009) also  supportsthe  analysis  findingthat  there  are  two preferredroutes  of  cyclone  passage  over  Japan. This study  showedoneroute  through Northeast China, the Sea of Japan, and the ocean to the northeast of Japan, and a secondroute  through  Taiwan,  the  southern  coast  of  Japan,  and  theocean to  thesoutheast of Japan. Cyclones followingthe first route are referred  to  as Sea  of Japan  cyclones  and  cyclones followingthe secondroute are called  Nangan cyclones. Although  these   routes   have   been   recognized   by   many   Japanese synopticians  (Takano  2002),  the  interannual  variability  of  the  route  has  not  yet been documented with an objective statistical analysis.'''

Examples

 * February 2014
 * -http://www.rms.com/Catastrophe/Catupdates/CatSummary?event_id=4116 http://www.accuweather.com/en/weather-news/heavy-snow-flooding-to-japan/22965265
 * -http://www.smh.com.au/world/second-japan-snow-storm-leaves-thousands-stranded-as-death-toll-rises-20140218-hvcwa.html


 * 6-7 April 2013 -http://www.bbc.co.uk/weather/features/22068996 3 deaths. http://www.japantimes.co.jp/news/2013/04/06/national/powerful-storm-dumps-rain-on-much-of-nation/ http://www.japantimes.co.jp/news/2013/04/09/national/parting-shots-are-forecast-after-big-storm-kills-three/ http://english.kyodonews.jp/photos/2013/04/218438.html
 * March 2-3 Sakhalin, Russia?
 * January_2013_Northwest_Pacific_bomb_cyclone
 * April 3 2012 -http://www.bloomberg.com/news/2012-04-03/japan-s-strongest-storm-since-1959-forecast-to-slam-into-tokyo.html -http://www.accuweather.com/en/weather-news/japan-storm-likened-to-typhoon-1/63588 -http://www.japantoday.com/category/national/view/kanto-workers-urged-to-go-home-early-ahead-of-typhoon-strength-winds -http://rt.com/news/japan-strongest-storm-tokyo-105/
 * 2011 18 December Kolskaya_(jack-up_rig)?? Russian far east.
 * 1988 14-15 March -http://www.sciencedirect.com/science/article/pii/S0422989408701090
 * 1994 12 February.
 * "Hokkaido Hurricane" May 1954 ???????????? could have been tropical-http://trove.nla.gov.au/ndp/del/article/23417157