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Ninomiya, K., 2014: Genesis of a weak polar mesoscale cyclone in the lee-side shear-zone south of the central part of Japan on 7-8 March 1992. : An observational case study. J. Meteor. Soc. Japan, 92, 347-361.
https://doi.org/10.2151/jmsj.2014-405

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Highlights:

• Genesis of a weak polar mesoscale cyclone (PMC) over the coastal Pacific south of central part of Japan on 7-8 March 1992 is studied using data obtained at two research vessels and observation stations, satellite cloud images and ERA40 data.
• A lee-side shear-zone formed to the south of Japan under the weak polar-air outbreak, between the northwesterly streams passing along the western side of the high-mountains area and northeasterly streams passing along the eastern side of the high-mountains area of Japan.
• A cumulus-line that formed in the shear-zone developed into a comma-shaped cloud system of the PMC within several hours (Fig.1).
• Despite strong baroclinicity in the low-middle troposphere, the PMC did not develop into a significant depression, and disappeared with in ∼2 days after generation (Fig.2). The synoptic-scale conditions for this non-developed PMC are compared with conditions for developed PMCs studied in previous articles. The conditions for this non-developed PMC were characterized by absence of the associated upper cold trough, lack of significant background low-level cyclonic circulation, and PMC location outside a zone of strong sea-surface temperature gradient.