A study of heavy, wet snowfall event from January 11 to 12, 2022 over Sapporo, and a comparison with previously recorded heavy snowfall events

Abstract

This study examined the reasons for the heavy wet snowfall measured from Jan. 11 to Jan. 12, 2022 over Sapporo and the singularity of the case. To examine the reasons, analyses using measurement data of AMeDAS from 2005 to 2022, pattern clustering of mean sea level pressure by self-organizing map (SOM), and numerical simulations by the meteorological model coupled with a process-tracking scheme were conducted. The analysis for the AMeDAS measurement data clarified that the snowfall density from Jan. 11th to Jan. 12th was the largest over the past 17 years. The SOM’s analysis indicated that the heavy, wet snowfall did not always occur under a common weather map pattern. The results of the numerical simulations elucidated that the heavy wet snowfall did not originate from rimed particles but from sleet or a mixture of rain and snow under conditions with high temperature and relative humidity.