Normal monsoon expected in 2022

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Monsoon 2022 prediction        (Posted on: April 14, 2022)                                                             

 

Prepared and copyrighted by WeatherCast Pvt Ltd

 

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The monsoon 2022 season is less than 60 days away and we at WeatherCast LLP analyzed all available data and maps and have come up with our version of the forecast. The forecasts presented in this document are a combination of statistical modeling, physical interpretation from long-range models on evolution of major drivers such as ElNino Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), Indian Ocean Sea surface temperature, Madden Julian Oscillation (MJO), sub-tropical jet stream and a few other minor drivers.

 

KEY POINTS ABOUT MONSOON 2022 

 

1. Based on our incisive analysis, we have come up with the following prediction for Monsoon 2022 season that runs from June to September. The country wide performance is expected to be between 94% to 106 % of Long Period Average (LPA), where LPA for India is 880 mm. 

 

To be more specific, we at WeatherCast LLP predict overall monsoon 2022 season to be at 100% ± 6% (model error), which translates to 94% to 106 % of LPA. Therefore, in terms of rainfall we expect anywhere between 827 mm to 930 mm with a mean value of 880 mm for the 4-month long monsoon season. Under the prevailing conditions, we give a 60% chance of a normal monsoon year. There is a dynamical reason for giving such a wide margin of ± 6% (model error), which we explain below.

 

Forecast range in %

Forecast range in numbers

Outlook

Confidence level

100% ± 6% (model error)

880 mm ± 52 mm

Normal season

60%

 

As per current conditions, there is a 60% chance of a NORMAL season while 20% chance of an above normal season and 20% chance of a below normal season exists. 

 

2. Monsoon predictions at this time of the year depends primarily on conditions in Pacific Ocean, Indian Ocean, and the northward movement of jet stream. Looking at all the drivers, our team felt that weak LA NINA conditions are likely to continue until July 2022. The easterly trade winds are active and a warm bias persists over Western Pacific. 

 

The IOD will start showing its effect from July onwards, and until then it is likely to be NEUTRAL. There is model divergence as to whether neutral conditions will prevail or negative IOD will develop. This is going to be a major factor in how monsoon currents evolve after July 2022.  Our team expects that weak La Nina will vane beginning August 2022, and neutral ENSO conditions would prevail. Therefore, we believe (with a 60% confidence) that this season is expected to be a mix of weak La Nina and neutral IOD. Any deviation in development of ENSO & IOD will impact the monsoon, which is the reason for a wide range of 94% to 106% (see above).

3. MJO is another factor, which if it becomes stationary in the Indian Ocean, then will cause monsoon to perform below normal and vice versa. Currently, the indications are that MJO will spend more time in Phases 3-5, which is good for monsoon. However, this is also with only a 50% confidence. 

 

Lastly, jet stream patterns are looking conducive for monsoon current to freely flow over India, which is good news. However, other major drivers (discussed above) have a tendency to impede the flow depending on their evolution. But for now, we are not putting too much emphasis on this. 

 

4. Given all the synoptic conditions, at present we are going ahead with an assumption of weak La Nina and neutral IOD year for 2022 (at least until July or mid-August 2022). Based on the statistical approach, the state-wise distribution would likely be as follows:




Yellow is a new color that we have added, which signifies “borderline” and means that the overall rainfall for the state could either be towards deficit or normal category.

 

Deficit means > -20% departure                      Normal means +20 to -20% departure                             Above normal means > 20% departure  

 

[Note: June and July months are likely to perform very well. The performance of August and September is very likely to depend on the evolution of IOD. If IOD remains neutral for whole of monsoon season, then good rains are expected in Aug & Sep, otherwise deficient for those months.] 

Our team will keep a close watch and keep revising the forecast as per the dynamical changes. And these revisions would be made much in advance, so as to help with planning and management.

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