Indian Metrological Department, Government of India, issued a warning on the 7 February 2022, that there would be rainfall on the evenings of 9 and 10 February 2022 in Sikkim, along with 15 other states and union territories. These forecasts and warnings and rainfall/snowfall have been a frequent occurrence in recent months. Despite the fact that it hasn’t even been a fortnight into February, these rainy and snowy phenomena have been plaguing Northern, North-Western and North-Eastern parts of India. Due to the trending narrative of Climate Change, which is an evident phenomenon that has definitely helped some unprecedented weather appearances, but the current weather conditions are all indebted to a cascade of Western Disturbances. Indian meteorologists coined this term to describe the systems moving from the west to the east direction.
Western disturbances are extratropical storms originating in the Mediterranean region that brings sudden winter rain to the northern parts of the India. They are low-pressure systems that originate over the Mediterranean or the Caspian Sea and are pushed towards the Indian subcontinent due to the high-altitude westerly winds. These disturbances collect and bring in moisture from various sources including the Mediterranean Sea and the Arabian Sea to India. Western disturbances, specifically the ones in winter, bring moderate to heavy rain in low-lying areas and heavy snow to mountainous areas of the Indian Subcontinent. They are the cause of most winter and post-monsoon season rainfall across northwest India, as they attract moist winds from the North Indian Ocean and limits north-Westerly cold winds from Central Asia. Western disturbances are usually associated with cloudy sky, higher night temperatures and unusual rain.
Dr RM Saxena, a professional meteorologist at Sky met weather defines a Western Disturbance as “a low-pressure area or a trough over the surface or the upper-air in the westerly winds regime, north of 20 degrees north, causing changes in pressure, wind pattern and temperature fields. It is accompanied by cloudiness, with or without precipitation.” – via First post
The unusual snowfall in Sikkim the past couple of months, and in the past couple of winters, have all been because of the Western Disturbances that have been forecasted by the IMD. Speaking to Sikkim Chronicle, Dr Gopi Nath Raha, Scientist and Central Public Information Officer, Metrological Centre Gangtok, Indian Metrological Department, illuminated that Western Disturbances aren’t a phenomenon that’s uncommon, they are global phenomena, and there are generally 5-6 of these disturbances each month in winter.
“These forecasts and changes in weather aren’t a cause of the climate change, we need more time to analyze the data, maybe 3 to 4 more years’ worth of data to see if there have been any changes in the weather patterns other than because of the Western Disturbances” Raha said clarifying the changing weather patterns in Sikkim.
There have been forecasts owing to the surge of Western Disturbances since late December last year and early January this year, and they have been only increasing, while the forecast for 9th and 10th February was all due to two consecutive Western Disturbances that hit the Indian subcontinent.
“Western Disturbances are nothing but a system of weather patterns that can be tracked and forecasted more easily compared to other systems. They are a wave like pattern that originate from the Mediterranean or Caspian Sea, and they can be easily tracked due to their wave like patterns,” Raha explained.
“We can easily determine their positions with the help of satellite imagery and also from seeing pictures from our (IMD’s) observatories. The most important factors that cause winter rainfalls or snowfalls in Indian subcontinent are the strength of the Western Disturbances and their position” he added.
Raha also explained that what happened this year is that we have experienced 6 to 7 strong western disturbances compared to the last few years and that have facilitated the snowfall in the lower regions of Sikkim on 5 February as opposed to the snowfalls that occur in the higher regions, this was solely because of the strength of the western disturbances. He also informed that this was almost after 10 years that this happened.
“IMD issues long term analysis and what we have seen this year is that the minimum temperature was 1.1 degree Celsius which happened after 14 years, and if we move to Tadong region which is considerably in a lower altitude compared to Gangtok observatory height and the lowest temperature we observed was 2.3 degree Celsius, these numbers tend to change, and we cannot say that this is due to Climate Change, not before we get more data and do more analysis,” Raha clarified touching on the point whether the unprecedented weather conditions were because of the Climate change.