Forecasting hailstorms over India

Abstract

It is generally believed by forecasters that hail may occur whenever severe thunder storms are expected. However, it is seen that most severe thunderstorms in India are not normally accompanied by hail. Hence, synoptic-thermodynamic investigations of the conditions that produce hailstorms have been undertaken. After discussing -the geographic and seasonal distribution, of hail frequency over India, the authors, investigated the role of the height of freezing level on incidences of hailstorms. The general belief that hailstorms are invariably associated with thunderstorm clouds which tend to develop to great heights, has not been found to have been substantiated from the available data. The relationship between the magnitude of updrafts and hailstorm formation in cumulonimbus clouds have, also been investigated. The correlation between the southernmost extension of sub-tropical front and southernmost boundary of the region predominantly affected by hailstorms has been, pointed out The role of strong wind field and large vertical shear in hailstorm formation has also, been studied. Synoptic situations characteristic of hailstorm situations in India, to be of goat use to the forecasters, have been evolved.