What causes winter rain?
Be it winter or winter rain, you can put the blame on the Western Disturbance, very well known for causing trouble related to weather. You hear about it all the time, from the met guys, in the news, tabloids, everywhere! Western Disturbance is the primary winter system which brings change in the winter weather in North India from November to February. In the met language, a Western Disturbance is an extratropical storm which originates in the Mediterranean and brings sudden winter rain and snow to the northwestern parts of the Indian subcontinent, also affecting the weather in other countries, like Pakistan, Bangladesh and Nepal.
However, Western Disturbances aren’t the only cause of rain in India during winter. There’s something more that causes winter rains, and these are cyclonic circulations (induced system associated with the Western Disturbance). These systems are generally seen forming in Rajasthan, north Gujarat, extending up to parts of Madhya Pradesh. Cyclonic Circulations change the wind profile in North India and and acts in tandem with WD to give good amounts of rain and snow.
Winter rain different in February
In the thick of winter, i.e. in the month of January, the winter rain pattern is generally more extended and intense, as the winter systems travel in the lower latitudes and are much more frequent and strong in nature. This year, a short but strong spell of rain and snow, from 22nd to 23rd of January caused Jammu and Kashmir to receive its heaviest snowfall of this winter season.
But winter rain in February has different traits. Rain that occurs in the month of February is sporadic and not too intense. At times it occurs without a sufficient notice. Neither does the rain in February add largely to the winter chill , nor does it provide enough moisture in the air for dense fog to form or to affect for a longer time, unlike in January. Since the weather systems track southwards in India in the month of February, they bring light but widespread rain in not just North India but also in parts of Gujarat, Rajasthan and west Madhya Pradesh. February is the last month and the last opportunity for North, East and Central India to enjoy the winter season, before the transition to a new and warmer season.
What we missed this time
Though winter rain did occur this year, there were couple of things that were missing. The supposed icy month of December remained relatively warm this year and saw very little rain and snow that make the weather in the hills and plains of North India cold. Lesser number of dense fog days in North India this winter, have also been attributed to drier days, less rain and enough moisture for fog formation.
Thundershowers and hailstorms, another important feature of the winter rain in North and East India was missing this time around. “Hailstorms generally go unreported as they aren't too common or frequent. However, when they do occur, they cause significant damage to life and property and crops. We did record one or two instances of hailstorm in Kanpur in Uttar Pradesh in Jan 2014 which posed a threat to the wheat crop”, said a senior meteorologist at Skymet Weather.
“Thunderstorms and thundershowers, most common to the winter season also remained absent this year. Clearly, I do not remember more than one instance of thundershowers (January 22nd) this time”, added the meteorologist.
Photo by Ritika Acarya.