Private weather forecaster Skymet Weather on Monday issued a revised forecast for the southwest monsoon, stating it now expects monsoon rainfall to be 85% of the long period average (LPA), with a 70% probability of drought. In its initial forecast issued in April, Skymet had forecast the monsoon to be 94% of the LPA, flagging a worsening trend, aided by a strengthening El Nino.
“Skymet predicts that August may end with a monthly shortfall of 16% rainfall of LPA. Growing El Nino and weak Indian Ocean Dipole (IOD) will cast a shadow, and the month of September is likely to be rain-deficit by 20% of LPA,” it said on Monday.
“Skymet foresees a 70% chance of drought and expects the seasonal rainfall to be 85% of the Long Period Average (LPA),” it said in a statement on Monday. Skymet said the remaining month of August is likely to see inequitable distribution over the four homogeneous regions of the country, with a strengthening El Nino and weak Indian Ocean Dipole (IOD) causing the deficit to increase further in September.
To be sure, the India Meteorological Department (IMD) in its April forecast had said the monsoon rainfall was likely to be 92% of LPA this year. However, in its June outlook, IMD revised this forecast downward — to 90% — and attached a 60% probability to a deficient season, meaning there is a better-than-even chance that total rainfall falls below the threshold that even qualifies as below-normal. As of August 17, the all India rainfall was 13% below LPA. August has largely seen the monsoon deficit stay static, between 11-13%. This deficit stood at -13% as of July 31 – an improvement from the -40% India saw at the end of June. Between June 1 and August 17, India has received 518.7mm, down from the 596.2mm it should have received normally during this period. India typically logs 870mm (87 cm) in the entire monsoon season.
IMD has not shared a revised forecast for the overall monsoon season since. This, despite substantial recovery in July, which brought the overall monsoon deficit down. Forecasts by IMD show the monsoon is already weakening in the second half of the month, with the trough shifting to the foothills. Skymet Managing Director Jatin Singh the El Nino was gaining strength and thus negatively impacting the monsoon. “Strong coupling of the atmospheric and oceanic circulation across the equatorial Pacific Ocean is raising the probability of a powerful El Nino. It is likely to make a transition from the ‘strong’ to ‘very strong’ category during early September. The ‘Super El Nino’ events tend to tilt the odds and presage a weaker monsoon.
it said the IMD has been issuing regular updates on the monsoon, including long-range forecasts at the end of every month While it did not comment on Skymet’s forecast. “Another update will be issued by the end of August,” a senior IMD official said. Positive Indian Ocean Dipole is likely to develop, but there remains some uncertainty in its timing and strength,” he said.
