Northwestern India bore the brunt of one of the longest fog spells in recent years and recorded the second-lowest January rainfall in 123 years, with a deficit of at least 91%. The IMD said rainfall deficit across India has reached 58%.
A lack of snow at the start of the year has sparked widespread concern across the Himalayan states, with the region remaining largely dry as of Tuesday (January 30). However, a recent round of fresh snowfall has blanketed the mountain states. This is due to two strong western disturbances passing through the region one after another between this week and February 4th.
“The lack of rainfall is mainly due to a less active western disturbance this time around. Even those affected are very weak. Additionally, rainfall is usually not heavy in January, but this time it was particularly light. Our multi-model ensemble The forecast was also unable to predict it, especially for the north-western plains,” said Dr M Mohapatra, director of the Meteorological Department.
Why can’t IMD predict dry winters?
The unusually dry winter also appears to have taken the weather department by surprise, which had predicted above-normal rainfall in January in the plains of seven northern Indian districts. Four western disturbances affected the region starting on January 3, but all crossed India’s northernmost tip and were rather weak in intensity, leaving most mountaintops dry and snow-free.
According to Mohapatra, this could be due to a weather phenomenon called the North Atlantic Oscillation (NAO) index. “We realize that this is the root cause of the lack of rainfall. When the NAO index is negative, it is not conducive to winter precipitation.” said the head of IMD.
Meteorologists also noted a long-term trend of decreasing Western Disturbance (WD) frequency over northern India from December to February since 1990, a pattern linked to rising global temperatures and climate change.
“Winter precipitation totals are decreasing. Of course, the western areas are moving more northward. But that doesn’t mean it’s going to decrease every year,” Mohapatra added.
The longest period of fog and cold days
Amid sparse winter rainfall, the entire northern India was engulfed in one of the longest periods of fog that started on December 25 and continues till date. This also resulted in more than 10 to 15 days of cold weather in the Indo-Gangetic plains, with temperatures plummeting to below normal levels.
However, the intensity of this cold wave was much lower and affected a smaller area – mainly Punjab, Haryana, northern Rajasthan, Delhi and parts of Uttar Pradesh. The average monthly minimum temperature in January is about 14.6 degrees Celsius, slightly higher than the long-term average of 13.6 degrees Celsius, while the winter peak in northwest India in January is about 5.5 degrees Celsius.
February rainfall ‘above normal’
The IMD is confident that rainfall in February will be above normal, not just in northern India but in the entire country except southern peninsular India. February is still winter, but day and night temperatures will gradually begin to rise and are expected to be generally above normal this month.
The latest forecast shows that there will be no cold weather or cold wave weather in the country in the next five days. Northern parts of India will continue to experience intense winter rainfall and snowfall until February 4, with peak intensity occurring on February 1 and February 3-4. Most days are likely to be cloudy.
Isolated hailstones are likely to occur in parts of Punjab, Haryana and Delhi on Thursday (February 1), with strong and cold surface winds of 30 to 40 kilometers per hour expected to sweep across the region. The meteorological department also issued a fog warning until February 3.
Strong El Niño persists but may weaken from April
The IMD further said that the strong El Niño phenomenon in the equatorial Pacific persisted in January but may start to weaken from April. Forecasts indicate a 75% chance of El Niño transitioning to ENSO neutral between April and June, which could be a good sign for the southwest monsoon.
Mohapatra went on to add that most models indicate a rapid transition to La Niña around July to September, meaning Pacific surface temperatures are likely to get cooler. This is believed to be beneficial for monsoon rains in India. However, IMD will update its forecast next month.
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