Abstract
We made a quantitative forecast of precipitation based on the numerical prediction method, using three layer model of the atmosphere. Treating the transport of water vapour three dimensionally and considering the temperature change, the excess of water vapour over saturation was estimated, which we assumed to fall off entirely as precipitation.
These calculations were performed by the graphical method designed by Fjφrtoft, using the geostrophic approximation for the wind velocity.
The North American Continent was chosen as the forecasting a_??_ea. For 12 hour forecast, the coincidence between the observed and forecast precipitation was found to be fairly good both in amount and area. This result suggests the possibility of forecasting weather based on the large scale motion of the air.
Lastly, brief discussions were made on the non-adiabatic effect, which we disregarded in our practical forecasting.
