usable time造句

• The accuracy of the numeric weather forecasting is ascending steadily . now the short - term forecasting is obviously better than the subjective forecasting and the usable time of prognosis is 7 days . the forecasting content includes not only prognosis as in the past but also the forecasting of various weather factors and weather phenomena
  数值预报的准确率稳步上升，短期预报已明显优于主观预报，可用形势预报的时限已达7天，预报内容也从单纯的形势预报发展到各种气象要素和天气现象的预报。