On the use of Tephigrams for forecasting Nor'westers

Abstract

The special radiosonde ascents made Calcutta in  May 1951 and the  routine ascents of  the same days have been discussed with a view to  see how  far one can successfully  forecast   the occurrence of   nor' wester over Calcutta  subsequently  during the day on  the basis of  routine morning tephigram. It in found that the thermal structure of ten undergoes marked  variations  form  morning to evening  and that for  accurate estimate of the instability as is likely to develop by evening,  it is necessary to take due note of the synoptic  charts and also of the changes in the upper air temperatures during preceding days over stations to the west as shown by radiosonde data.