Failure of numerical model in predicting advance of monsoon in Delhi rare: IMD
Facing criticism over persistent errors in forecasting the progress of the southwest monsoon over Delhi, the India Meteorological Department (IMD) said on Monday that such failure by numerical models in forecasting monsoon over the capital is “rare”. and unusual”.
The Meteorological Department said its latest model analysis had indicated that low-lying moist easterly winds from the Bay of Bengal would spread over northwest India covering Punjab and Haryana by July 10, leading to the progress of the monsoon and an increase in rainfall activity. will increase. From July 10 in the entire region including Delhi.
Accordingly, moist easterly winds have spread over northwest India, the IMD said in a statement.
These moisture-laden winds cause cloud cover and increased relative humidity.
The weather department said that the winds have led to a revival of monsoon in the region and widespread or widespread rainfall activity has occurred over East Rajasthan, Himachal Pradesh, Uttarakhand, Jammu and Kashmir and scattered rains over Punjab and West Rajasthan.
However, it did not cause significant rainfall activity over Delhi even though there was rainfall activity over places around the national capital.
It also rained in the desert district of Jaisalmer and Ganganagar – the two last outposts for monsoon cover – and in peripheral areas of Delhi, but not in the capital.
“Such failure by numerical models in forecasting the advance of monsoon over Delhi is rare and unusual,” the IMD said.
“Needless to mention that the IMD has made good predictions with high accuracy about four to five days in advance about the advance of monsoon over Delhi in recent years and the advance of monsoon over different parts of the country during monsoon 2021. of it.” added this.
The IMD had said on June 13 that the southwest monsoon would reach the national capital by June 15.
After the onset of monsoon over Kerala on June 3, the wind system with favorable atmospheric circulation and a low pressure system over the Bay of Bengal continued to advance over the country till June 13, it said.
By June 13, it had covered most of the country except Northwest India.
On June 13, the Numerical Weather Prediction (NWP) model suggested favorable conditions with moist low-lying easterly winds over northwest India, bringing monsoon over most parts of Madhya Pradesh, remaining parts of Uttar Pradesh, Delhi, Haryana and Punjab. helped to move forward. in the subsequent 48 hours.
“Accordingly, a press release was issued on June 13 indicating the likely arrival of monsoon over Delhi by June 15,” the IMD said.
On June 14, however, weather analysis based on satellite and NWP model consensus indicated the approach of a trough in mid-latitude westerly winds, weakening the easterly winds over northwest India.
The IMD said that due to the unfavorable effect of this mid-latitude westerly winds, further advance of monsoon was not expected over remaining parts of northwest India including Delhi.
Accordingly, it issued an updated press release on 14 June indicating that the further advance of Southwest Monsoon into remaining parts of Northwest India including Delhi would be slow and delayed.
“However, this evolution of interaction with westerly winds could not be predicted from weather forecasting models,” the IMD explained.
On June 16, another press release was issued indicating a delay in the progress of monsoon over Delhi and slow progress over parts of northwest India.
Accordingly, Monsoon has further advanced into some more parts of Northwest India by 19 June. It did not move further due to weak or break conditions since June 20.
Press releases were issued on June 22, 24, 26 and 30 and July 1, showing the delay in the progress of monsoon over remaining parts of North West India including Delhi and weak monsoon conditions over the country.
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