On the Mechanisms of a Snowstorm Associated with a Low-Level Cold Front and Low-Level Jet in the Western Mountainous Region of the Junggar Basin, Xinjiang, Northwest China

Abstract

Snowstorms frequently hit large parts of the Northern Hemisphere, and their causative factors have been drawing increasing attention in recent years. As the first in-depth study on the mechanisms of a snowstorm associated with a low-level cold front (LLCF) and low-level westerly jet (LLWJ) in the western mountainous region of the Junggar Basin, Xinjiang, based on both observations and numerical simulation, the major findings of this work are as follows: At the early stage, instabilities were mainly dominated by inertial instability (II) occurring near the core region of the LLWJ, while the lower level was mainly controlled by the baroclinic component of moist potential vorticity (MPV2), which was mainly contributed by the vertical shear of the horizontal wind, which is also located near the LLWJ. At the later stage, II was released significantly, whereas the MPV2 still supported snowfall clouds. Further analysis based on the decomposition of the frontogenetical forcing required for the release of the instabilities indicated that the slantwise term was the major contributor, whereas convergence and deformation also played significant roles at low levels above the windward slope. The slantwise term resulted from the combined effects of baroclinicity due to the LLCF and the inhomogeneity of the momentum due to the LLWJ.

Urbanization Effect on Changes in Extreme Climate Events in Urumqi, China, from 1976 to 2018

“…Urumqi, the provincial capital of Xinjiang, is the largest and the most-developed city in Xinjiang. It is located in the arid region of northwestern China, whose weather and climate are very sensitive to climate change [12,[37][38][39][40]. Therefore, it is important to study the UE on the local extreme climate events in Urumqi.…”

Simulations of a Heavy Snowfall Event in Xinjiang via the WRF Model Coupled with Different Land Surface Parameterization Schemes

“…So far, there have been few studies on the numerical simulations of heavy snowfall events in Xinjiang, especially those considering the impact of the land surface process on heavy snowfall [41]. This study selects a typical heavy snowfall event in Xinjiang from 9 to 13 December 2015 as the study case.…”

A Case Study on the Convection Initiation Mechanisms of an Extreme Rainstorm over the Northern Slope of Kunlun Mountains, Xinjiang, Northwest China

“…Consequently, associated natural hazards such as flash floods, urban waterlogging, landslides, and debris flows are posing serious threats to society, the economy, and personal safety [6][7][8][9]. Despite substantial progress in comprehending the structure and lifespan of convective systems, accurately forecasting the convective initiation (CI, which refers to the process by which air particles gain and maintain positive buoyancy after being lifted above the level of free convection, eventually forming deep convective clouds) remains one of the biggest challenges in meteorology [10][11][12][13][14][15][16][17][18][19][20][21].…”

“…Despite there being continuous improvements in weather forecasting and numerical simulation technologies, the prediction of localized short-term heavy precipitation remains a challenge due to the sparse observation stations and complex terrains in Xinjiang, especially in southern Xinjiang. Furthermore, in contrast to the relatively comprehensive and thorough investigations on intense rainfall events over the mid-eastern part of China [10,13,[38][39][40][41][42][43], there are relatively few studies on extreme rainfall events over the northern slope region of the Kunlun Mountains (KLM) in Xinjiang. In addition, to the authors knowledge, there has been no previous comprehensive and systematic study on the CI mechanisms of heavy rainfall in the northern slope region of the KLM based on high tempo-spatial resolution numerical simulations.…”