Diagnostic Analysis of A Severe Regional Snowstorm Event in the Early Winter of 2016 in Henan Province, China
Received:June 06, 2018  
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KeyWord:Snowstorm  “Cold air wedge”  Frontogenesis  Moist potential vorticity  Symmetric instability
Author NameAffiliationE-mail
FENG Lisha Troops 61741 of PLA, Beijing 100094
Henan Meteorological Observatory, Zhengzhou 450003 
SONG Pan Troops 96941 of PLA, Beijing 102208 songpannj@163.com 
ZHENG Fei Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029  
HE Zhe Henan Meteorological Observatory, Zhengzhou 450003  
KONG Haijiang Henan Meteorological Observatory, Zhengzhou 450003  
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      Based on conventional observations, L-band soundings, and NCEP reanalysis data, the key mechanisms involved in initiating and enhancing the first severe regional snowstorm of the early winter of 2016 in Henan Province, China, were diagnosed. Results showed a large-scale circulation that included a full-latitude shortwave trough and a stable cold vortex to the northeast. Southerly mid- to upper-air and northerly lower-level winds played an important role in the snowstorm. When an 850-925 hPa northeasterly jet provided a “cold cushion” by forcing warm and humid air upward, it and a 500-700 hPa southwesterly jet formed a strong vertical wind shear and a deep frontogenetic zone. This was conducive to ascension and frontal secondary circulation, which considerably enhanced the snowstorm. The warm and humid southwest 700 hPa jet was a key feature of the storm, transporting beneficial water vapor and convergence with the cold air behind the northeast cold vortex in the Huang-Huai area. This caused considerable dynamic lifting. The north-south migration of the convergent shear at 700 hPa caused two snowfall centers in midwestern and southeastern Henan. The snow zone moved with the southward migration of the “cold air wedge.” The atmosphere above the snow zone showed a positive wet barotropic term and a negative wet baroclinic term with large absolute values of both during the entire process. This was conducive to the release of symmetric unstable energy and the development of the snowstorm. The essential and significant conditions of the snowstorm are the upper-air shortwave trough, the mid-air convergent shear, the lower-level “cold cushion” and a frontogenetic zone.