[10] reported a deep convective precipitation event caused by thermally induced convergence over the Tian Shan Mountains; the low-level flow on the northern slope was controlled by northernly anabatic wind, while the upper-level flow was controlled by southwesterly cross-ridge wind, resulting in a vertical wind shear of 700-500 hPa. Vertical wind shear may have several impacts on cloud dynamics [14; 15; 16; 17; 18]. Firstly, strong low-level wind shear may result in more significant entrainment mixing near the cloud edges, inhibiting the vertical development of clouds, especially at the early stage of convective clouds [15]. Meanwhile, if there is sufficient convective energy and the low-level wind shear is balanced by a gust front, convection can be enhanced and new cells can be triggered [15; 16; 19; 20]. Secondly, vertical wind shear may influence the organization of convective clouds. Previous modeling studies have shown that strong low-level wind shear is favorable for the generation of quasi-line convective systems [14; 16; 21], while increasing middle-level shear results in more supercellular-like structures in deep convective clouds because stronger deep shear favors rotation to form a supercell [22]. Thirdly, at upper levels, strong wind shear tends to limit the upward development of deep convection by enhancing the turbulence over the cloud top and extending the anvil horizontally, thus reducing the precipitation intensity [23; 24]. Vertical wind shear also influences cloud microphysics, since particle trajectories are strongly related to cloud organization [17; 25; 26]. For example, using an idealized simulation, [PERSON] et al. [25] showed that weak wind shear leads to a positive aerosol effect on convection development, while strong wind shear leads to a negative aerosol effect on convection. [PERSON] et al. [17] found that ice production through the riming-splinter process may be hampered by strong wind shear, which may further influence the cloud structure and precipitation rate. Most of the previous studies mentioned above were based on model simulations focusing on deep convective clouds, while a few focused on shallow cumulus [18]. Observations of the fine structures and evolution of orographic clouds in an ambient environment with strong vertical wind shear are still limited, especially over complex terrain such as the Tian Shan Mountains. With the advances of instruments, high-resolution observational techniques have been used to study the clouds and precipitation over complex terrain, among which millimeter radars have been demonstrated to be useful for investigating cloud structures because of their high temporal and spatial resolutions [27; 28; 29; 30]. Therefore, the aims of the present study are to investigate the fine structures of thermally forced orographic clouds over the Tian Shan Mountains using millimeter radars, including a Ka-band cloud radar and a K-band micro-rain radar, and to explore the roles of thermodynamic instability and vertical wind shear in cloud development based on the radar observations as well as a convection-permitting simulation using the Weather Research and Forecasting (WRF) model. The paper is organized as follows: Section 2 describes the field experiment carried out and the ambient conditions in this case, as well as the model setup; Section 3 shows the results of radar observations and the model simulation; Section 4 contains a discussion, and the conclusions are presented in Section 5.