Forecasting of precipitation is discussed with the same idea of integrated atmosphere. As the precipitation is expressed by continuty equation, we integrated it by use of mean value theorems and found that the precipitation is shown approximately by following formula.
Where m: amount of precipitation per unit time and unit area, σ^*: mixing ratio on the 700 mb surface, Q^*: velocity divergence on the 700 mb surface. Q: velocity divergence on the 500 mb surface. And we tried to explain using above formula the synoptic situation and compared the calculated rain with the observed one.