Based on the Lband sounding data, automatic weather station data, conventional observation data, NCEP global 1°×1° reanalysis data, the formation mechanism, characteristics of development processes and transmission mechanism of a persistent advection fog occurring over the north of the Yellow Sea during 23-24 April 2012 were analyzed. The results show that this fog belongs to an advection cooling fog. It was a result of interaction between cold sea surface and warmwet air flow. The sustained ridge over the Yellow Sea blocked and weakened the cold air, and it was favorable in establishment of a stable stratification in the lower layer of atmosphere. The sustained and strengthened transport of moisture by the southerly in the lower layer over the Yellow Sea not only provided abundant moisture for formation of the fog but also facilitated northward spreading of the fog areas. The “warm dry layer” above the fog layer and the underlying cold waters in the northern Yellow Sea were the primary factors for development and maintenance of this advection fog. The dense fog area corresponded to the cold advection area and the moisture convergence zone in the nearsurface layer. The area of merging of the cold and warm advections was prone to fog occurence. Under stable synoptic situation, the increase of southerly wind speed in the northern Yellow Sea did not affect maintaining of the advection fog. This unique character can be evidently distinguished from radiation fog.

Based on CMA Tropical Cyclone Yearbook，FY-2G temperature of brightness blackbody (TBB) product (0.1°×0.1°), hourly rainfall observations from automatic weather stations, conventional observation and ERA-Interim reanalysis data（0.125°×0.125°）, the heavy precipitation process in the Liaodong Peninsula caused by typhoon Rumiba (1818) was analyzed preliminarily. The major conclusions are as follows: (1) The difficulty of “Rumiba” prediction was to predict the turning point and the track after landing. The eastward movement of westerly trough and continental high blocked the westward movement of “Rumiba”. The northward position of the subtropical high caused by northwesterly movement of typhoon “Soulik” and the continental high in northeast China were favorable for the northward movement of “Rumiba”. (2) The low-level southeast jet forming between typhoon “Rumiba”, “Soulik” and the subtropical high provided continuous water vapor and energy, which was conducive to maintaining the intensity of “Rumiba” and inducing continuous occurrence of the heavy precipitation in the Liaodong Peninsula. (3) The interaction of “Rumiba” in transformation process with westerly trough and low-level jet was beneficial to the development of spiraling cloud system on its north side. The heavy precipitation area was closely related to the cold and warm advection in the convergence zone of the north side of low-level typhoon circulation. And the energy front zone appearing at the intersection of cold and warm advection was a good indication for heavy rainfall. (4) There were great differences in the prediction of turning point and path after turning from numerical prediction models. In addition to referring to ensemble prediction products, the similarity prediction method can also be used to compare and analyze the large-scale environmental field of the similar individual cases, and the correction can be carried out with the help of the numerical prediction products and the similar individual cases.