Rainfall around monsoon depressions over India

Abstract

Rainfall that occurrs for 2 to 3 days within a radius of 350 miles from the centre of a depression along its track has been combined using the data of all raingauge stations within that area. Such 'composite' charts of rainfall were prepared for a sample of three mid-monsoon depressions in the year 1944. Falls of heavy rain of 3 and above in 24 hours are confined to an area lying to the left hand side of the track. On any particular morning, the heavy rainfall area extends to about 300 miles ahead and to about 300 miles behind the centre of the depression on that morning, measured respectively along the expected and past track of the depression. The  width of the area is about 250 miles and extends to the left of the track. It is further noticed that out of this  belt, about 30 per cent of the area is almost the maximum over which there may be rainfall of 3" or more in 24 hour's. The results are discussed from a forecaster's point of view.