Tribune News Service
New Delhi, July 13
A day after official forecaster India Meteorological Department (IMD) issued a detailed clarification over its inaccurate forecast on the progress of Southwest Monsoon to Northwest, including Delhi, the seasonal rains finally arrived over the National Capital on Tuesday, almost 16 days behind the normal date of onset. The rains also covered the entire country, later than the normal onset date of July 8.
In 2020, Monsoon had covered India by June 27, almost 12 days in advance.
The weather office said: “in association with the continued prevalence of moist easterly winds from the Bay
Under the influence of these conditions, “scattered to widespread to widespread rainfall” is very likely over parts of Northwest during next three days along with “isolated heavy to very rainfall” over Uttarakhand, Himachal Pradesh, and West Uttar Pradesh. It also warned of a thunderstorm with lightning over Punjab, Haryana, north Rajasthan, West Uttar Pradesh and Bihar during the next 24 hours. This may cause injuries leading to casualties to people and animals staying outdoors”, it cautioned.
Meanwhile, “fairly widespread to widespread rainfall with isolated heavy to very heavy falls” are also very likely along the west coast, adjoining inland areas, and peninsular India during the next four days.
Facing severe criticism over repeated wrong forecasts on monsoon’ arrival over Delhi, the weather department yesterday called such failure by numerical models in predicting its advance “rare and uncommon”.
“Such type of failure by numerical models in prediction of monsoon advance over Delhi is rare and uncommon,” it said as it explained how rains progressed till June 13 in association with favourable atmospheric circulation and a low-pressure system over the Bay of Bengal since onset over Kerala on June 3.
By June 13, it covered most parts of the country except for Northwest India.
On June 13, numerical weather prediction (NWP) models suggested favourable conditions for its further advance following which a statement was issued indicating likely advance of monsoon to Delhi by June 15, the IMD said.
However, on June 14, weather analysis based on satellite and NWP model consensus indicated the approach of a trough in mid-latitude westerly winds, leading to weakening of easterly winds over northwest India. Accordingly, the IMD issued an updated statement on June 14, indicating that further advance into the remaining parts of Northwest India, including Delhi, will be slow and delayed.
“However, this development of interaction with westerlies could not be anticipated by the weather prediction models,” it said.
On June 16, the IMD issued another statement indicating further delay and slow progress. Since June 20, there has been no further advancing due to weak/break monsoon conditions and statements were issued on June 22, June 24, June 26, and June 30 and July 1, indicating a delay in the remaining parts of Northwest, including Delhi and weak/break monsoon conditions over the country, the IMD clarified.
Then on July 5, it issued another statement, stating that monsoon will advance into remaining parts of West UP, some more parts of Punjab, Haryana, and Rajasthan and Delhi on July 10.