Kinetic energy budgets were prepared for lower tropospheric jet stream accompaning storm rainfalls of two courses in 1993 and 1994,with the use of analyses from a limited-area fine-mesh model (100× 100km²,ten layers) as well as objective analysis system. It shows that the generation rate of kinetic energy (K) by pressure forces is always two-three orders bigger than change rate of K for every time. But the average generation rate as 200—206W/m² respectively, and the former was a source of kinetic energy (characterized by a large-scale direct solenoidal circulation, the latter was a sink for subgrid-to grid-scale energy transfer,done by a indirect solenoidal circulation. So the kinetic energy changes of the small (subgrid-) scale flow (lead by storm motions) paralleled those of the large-scale flow. This indicates a need for considering the apparent phenomenon of negative viscosity in mesoscale numerical atmospheric modeling for prediction of storm rainfalls.