Abstract
A mesoscale objective analysis of the wind and moisture field around the thunderstorms which developed over the NSSL observation network on May 28,1967 is made. The scheme of the objective analysis includes the “ time to space conversion ” of the observation relative to the mesosystems. The weighting function for the interpolation depends on both the distance between grid point and observation and the time difference between observation and analysis time. The distributions of wind and moisture obtained by the present analysis coincide fairly well with that obtained by subjective analysis.
The morphological description of the change in the environmental situation of the thunderstorms is also attempted on the basis of the obtained wind and moisture field. The convergence line, which is formed along the northern boundary of the predominant low-level southerly winds, is simultaneously intensified with the thunderstorms' development. While the middle tropospheric wind field is not modified by the thunderstorms' development, a remarkable change of winds is found at 250 mb level, where the upper outflow from the storms modifies the flow into a strong diffiuence flow pattern. The analysis of the moisture field indicates that the storms' development is associated with the increase of moisture convergence in the lower layer.
