Investigation was conducted of the digitized radar data operating at Hangzhou and 1 h autographic rainfall from related 58 surface and 156 hydrological stations over Zhejiang province in typhoon seasons 1989～1992, deriving the echo vigor Z and rainfall intensity I associated only with typhoons striking the region during the seasons. Forecasts of 0～3h rainfall category were made following the Z-I relation obtained based on coefficients A and b in Z=A·I^b found over a range of domains in conjunction with the migration of echoes.