%0 Journal Article %A ZHANG Junlan %A PENG Jun %T A Forecast Analysis of Precipitation Phase Transformation and Rainfall Intensity in Spring over Northern Xinjiang %D %R 10.7522/j.issn.1000-0534.2016.00094 %J Plateau Meteorology %P 939-949 %V 36 %N 4 %X A large-scale rain followed by snow and heavy snow process happened in northern Xinjiang from 13 to 15 April 2014, which has brought serious impact on local agricultural, works and people's life. Using the diagnosis method of the weather, the forecast index of phase transformation between rain and snow as well as rainfall intensity was studied. The result shows:(1) Change of temperature at middle-low level is the key factor and index to Forecast precipitation phase transformation in spring in Northern Xinjiang. (2) Temperature at the middle level is a key factor to distinguish between the snow and sleet. Sleet turning to snow when the temperature is less than -25℃ on 500 hPa and less than -12℃ on 700 hPa; Temperature at the low level can distinguish between the rain and sleet, rain turning to sleet in the case of the temperature less than -2℃ on 850 hPa and less than 2℃ on 925 hPa. Additionlly, the forecast index of sleet turning to snow when the temperature is less than -4.5℃ on 850 hPa. (3) Cooling condensation of water vapor plays an important role on precipitation process in spring over the northern edge of the Northern Xinjiang and the Tianshan mountainous. Cooling condensation of the lower water vapor is an important factor affecting the rainfall intensity. There are more water vapor、stronger cold air、thicker condensation which can induce longer and stronger rainfall. The rainfall intensity is decided by the cooling condensation of water vapor. %U http://www.gyqx.ac.cn/EN/10.7522/j.issn.1000-0534.2016.00094