Impacts of the Dabie Mountains on a Mesoscale Convective System that Occurred in the Background of the Northeast Cold Vortex

A severe convective case occurred in the background of the northeast cold vortex (CC) on May 14, 2017, in the Yangtze and Huaihe River Base, which brought short-term intense precipitation, hail, and high wind. The CC affected by topography and solar radiation needs to be studied; it is difficult to forecast because of complex influencing factors. In this paper, the ensemble Kalman filter technique is used to assimilate the radar radial wind, radar-retrieved wind, GPS water vapor, radiosonde, and hourly surface observational data. The occurrence and development process of the convective system are simulated, and the impacts of solar radiation and the Dabie Mountains are studied by sensitivity experiments. Observational and numerical experiments demonstrate that the cold pool of CC encounters the Dabie Mountains and triggers convection in the mountain, which is then amplified by the cold pool and organized into a short linear system with the CC. Results demonstrate that solar radiation is the main factor that affects the occurrence and development of CC and the Dabie Mountain convection (DMC), and the topography affects the occurrence and development of DMC through the strengthening effects of solar radiation. In this case, DMCs are generated at three places ( A, B, and C), and the main affecting factors are slightly different. Cold pool and solar radiation are the main factors that affect the occurrence and development of DMC, which is nearest to CC and on the north slope of the Dabie Mountains. The topography is a secondary factor affecting the development of convection by strengthening the lifting of the cold pool and the short wave radiation heating of solar radiation. The generation time of convection B and C is close, and they both have a certain distance from CC. The main influencing factor is solar radiation, and the topography is the secondary factor. Induced by their cold pools, the DMC and CC organize into a short linear system. The convergence area formed between the cold pools of DMC and CC establishes a connecting bridge between them so that the western DMC develops eastward, and the convection in the middle of them is amplified. Eventually, the eastern CC and the western DMC connect to form a short convective linear system.