Even as global models are drumming up a consensus over El Nino unfolding later this summer, the “spring predictability barrier” has prevented them from taking a call on the intensity or impact of the event on the June-September monsoon. Most models have concluded that the prolonged La Nina has ended, and the East Equatorial Pacific is transitioning into a “neutral” state before giving in later to alter ego El Nino. Here, the Application Laboratory of Jamstec, the Japanese national forecaster, stands out by suggesting that El Nino would be a weak event this year.
The La Niña decayed into a transitional “La Niña Modoki”-like state, the Japanese agency said. The SINTEX-F ensemble mean predicts that an El Niño will occur as early as in May, though there is a large uncertainty in the predictions of the amplitude. The ensemble mean of the SINTEX-F2-3DVAR version predicts a relatively weak El Nino.
Cooler pre-monsoon period
South Korea’s APEC Climate Centre says during April-June, the probability of “neutral” (neither El Nino or La Nina) conditions is expected to be 53 per cent, which is slightly higher than that of El Niño conditions. For the remaining forecast periods, El Nino probability increases and gradually becomes dominant (above 91 per cent). What is interesting could be the build-up during April and May, normally when the heat begins to build up over North-West India, adjoining Central India and even East India. Most models indicate prevailing thunderstorms would continue and cool down most of the country during April as well. This may rule out customary heat waves during this period, per these models.
An India Meteorological Department (IMD) outlook for March 23-29 has already indicated western disturbance activity and an induced cyclonic circulation will trigger isolated to scattered rain and thunderstorms over the hills of North-West India and adjoining plains during many days of the week. Similarly, a trough will combine with a cyclonic circulation over the East and the South to bring isolated to scattered rain and thunderstorm over the region. Overall, rains will likely stay above normal over the South and the hills of North-West India; below normal over North-East India; and near-normal over the rest of the country. Global models cited above say this pattern will continue through April.
Varying model outlook
businessline tracked temperature outlook for April to May (pre-monsoon months) and rainfall outlook for the South-West monsoon (June to September) of five different models, highlights of which are given below (the IMD is expected to come out with its eagerly awaited first long-range forecast for the 2023 monsoon by mid-April).
1. Application Laboratory, Jamstec, Japan
Temperature: April-May-June: Rajasthan, Gujarat, west Madhya Pradesh, west Maharashtra, coastal Karnataka, Kerala and south Tamil Nadu are likely to observe warmer than normal conditions. North-West India, East India, East-Central India and north Tamil Nadu may stay cooler than normal
Rainfall: April-May-June: Normal for North-West India; above-normal for East India and entire southern half of the country except parts of central Madhya Pradesh.
Rainfall: June-July-August: Normal for North-West India, Tamil Nadu, Karnataka and Kerala. Above normal for Saurashtra-Kutch, west Madhya Pradesh, rest of Central India, East India. Rain deficit over central Madhya Pradesh, east Uttar Pradesh, Bihar, Jharkhand, West Bengal and coastal Karnataka.
Rainfall: September-October-November: Normal to excess over most of country except North Peninsula including north interior Karnataka, Madhya Maharashtra, Marathwada, Telangana and coastal Andhra Pradesh.
2. APEC Climate Centre, South Korea
The South Korean agency gives detailed seasonal as well as monthly outlook for rainfall. It said India is likely to stay warm during April to May (pre-monsoon). Its rainfall outlook for individual is as follows.
April: Above normalfor most of country except the South Peninsula (coastal Karnataka, Kerala, Tamil Nadu, south interior Karnataka, Rayalaseema and coastal Andhra Pradesh) where it would be below normal.
May: Above normal for most of country including South. But below normal for parts of East India (Chhattisgarh, Odisha, Bihar, West Bengal and North-East India) and the foothills in Uttar Pradesh and Bihar.
June: Below normal for most of country except Jammu & Kashmir, Himachal Pradesh, and Punjab where it will be above normal. Excess also for Vidarbha, Goa, south Tamil Nadu and south Kerala.
July: Below normal for most of the country except East India (Chhattisgarh, Odisha, east UP, Bihar, Jharkhand, part of the plains and hills of West Bengal, North-East India and coastal Tamil Nadu where it will be above normal). Rain deficit likely to be predominant over coastal Karnataka and Kerala.
August: Rain deficit over western half of the country covering Rajasthan, west Uttar Pradesh, west Madhya Pradesh, Marathwada, Madhya Maharashtra, Telangana, Rayalaseema, south coastal Andhra Pradesh, Tamil Nadu, Karnataka and Kerala.
Above normal rain over Gujarat, Saurashtra-Kutch, Goa, extreme south Kerala and Tamil Nadu, east Madhya Pradesh, Chhattisgarh, Vidarbha, Odisha, foothills of Uttar Pradesh and Bihar, Jammu & Kashmir, Ladakh, Punjab, Himachal Pradesh and Uttarakhand.
September: Mostly below normal for entire country. Only regions to see above normal rain are parts of interior Maharashtra, parts of Chhattisgarh, Odisha and Bihar; West Bengal, North-East India and Ladakh.
3. European Centre for Medium-Range Weather Forecasts
April to May
Temperature: below normal to normal for most of country. Heat waves less likely.
Rainfall: Above normal over most of country except Jammu & Kashmir, Himachal Pradesh, Punjab, Ladakh, coastal Karnataka, Goa, Madhya Maharashtra and west Madhya Pradesh. The deficits will turn to normal from first week of April towards May with North-West India and East India being above normal.
4. IRI, Columbia University
April to May
Temperature: Normal except over Gujarat, Saurashtra and Kutch, Goa, coastal Karnataka and coastal Odisha.
Rainfall:
April-May-June: Normal for most of country except parts of southern parts of Kerala and Tamil Nadu and the ghats in between.
May-June-July: Normal for most of country.
June-July-August: Normal for most of country except Madhya Maharashtra and north interior Karnataka.
July-August-September: normal for entire country.
5. UK Met Office
April-May-June
Temperature: Warmer all over India except North-West India.
Rainfall: Above normal rain except parts of West and Central Madhya Pradesh, Telangana and coastal Andhra Pradesh.
May-June-July: Below normal over Gujarat, Saurashtra-Kutch, Rajasthan, Punjab, Haryana, Delhi, foothills of Uttar Pradesh and Bihar. Normal over rest of country.
June-July-August: Rain deficit over Gujarat, Rajasthan, Punjab and Haryana. Normal rain for the rest of the country.