Application of Convective Temperature in Local Thermal Convective Precipitation Forecasting
Thermal convective precipitation (TCP) is a usual weather phenomenon under subtropical high. TCP always occurs suddenly with small temporal and spacial scales, and it is a difficult point in the current weather forecasting operations. In this article, the convective temperature (Tc) is used to forecast TCP. First, the algorithm of Tc in MICAPS 3 is improved, and then the sounding and surface observation data from Nanjing Station in July and August during 2004-2013 are used to discuss the feasibility of forcasting TCP depending on Tc under the control of subtropical high. The results show that, the average probability of TCP occurrence at Nanjing Station is 1/6. The probability of TCP occurrence increases and then decreases with the change of temperature difference between the day high temperature Tmax and Tc. When Tmax-Tc is smaller than -0.5℃, the probability of occurrence is lower than average probability. When Tmax-Tc is 0.5 to 1.5℃, the probability of TCP occurrence is the highest, reaching 40%. The two requirements for TCP occurrence under the control of subtropical high are Tmax > 30℃ and Tmax-Tc > -3.5℃. In addition, statistics of 34 TCP cases show that TCP mainly occurs from 13:00-18:00 BT every day and its duration is 50 min averagely with the mean precipitation being 7.8 mm.