Snowstorm over the Southwestern Coast of the Korean Peninsula Associated with the Development of Mesocyclone over the Yellow Sea

This study investigates the characteristics of a heavy snowfall event over the southwestern part of the Korean Peninsula on 4 December 2005.The snowstorm was a type of mesoscale maritime cyclone which resulted from barotropic instability,and diabatic heating from the warm ocean in continental polar air masses.Based on surface observations,radiosonde soundings,MTSAT-1R satellite data and the lO-km grid RDAPS (Regional Assimilation and Prediction System based on the PSU/NCAR MM5)data,the evolution of the mesocyclone is explained by the following dynamics;(1)In the initial stage,the primary role in the cyclogenesis process of the mesocyclone is a barotropic instability in the horizontal shear zone.(2)In the developing stage,the mesocyclone moves and deepens into a baroelinic zone corresponding to the surface heating and moistening.(3)In the mature stage,it is found that the mesocyclone is intensified by the destabilization caused by enhanced low-level heating and condensation,the moisture flux convergence,and the interaction between upper and lower-level potential vorticity anomalies. We suggest that a checklist with stepwise indicators responsible for development be prepared for the forecasting of heavy snowfall over the southwestern part of the Korean Peninsula.