The northeast monsoon is expected to bring better rainfall to southern Kerala this year even as northern parts of the state may receive below-normal rainfall, according to a meteorological assessment from the India Meteorological Department's recent seasonal outlook.
The IMD has forecast normal rainfall for South Peninsular India during the October to December period. However, meteorologists have cautioned that this broad regional forecast should not be interpreted as a single rainfall across Kerala. Regional variation is expected to be significant during the northeast monsoon season.
South Kerala Could Get Better Rainfall
Rajeevan Erikkulam, a meteorologist who is working in southern Kerala, said southern Kerala could see normal to above-normal rainfall during the northeast monsoon while northern areas of Kerala can expect below-normal rainfall.
He also cautions against viewing the IMD’s broader forecast for South Peninsular India as a forecast that every part of Kerala will receive normal rainfall. The distribution of rain can vary considerably between districts in the October to December season.
The northeast monsoon is also considered more erratic and spatially uneven than the southwest monsoon. Rainfall activity during the season can be strongly influenced by the development and movement of low-pressure areas and cyclonic systems over the Bay of Bengal.
Even if the seasonal outlook is favourable for southern Kerala in this regard, individual spells of heavy rain or extended dry periods can still happen depending on weather systems developing during the season.
Northeast Monsoon Expected In Third Week Of October
The northeast monsoon is expected to arrive over southern India around the third week of October according to the latest IMD outlook. The weather agency has forecast rainfall between 88 per cent and 112 per cent of the long-period average for South Peninsular India during October to December, which is within the normal range.
The South Peninsular India region includes Kerala, Tamil Nadu, parts of Andhra Pradesh and Karnataka. The northeast monsoon is particularly important for Tamil Nadu, where a large part of annual rainfall takes place in the October to December season.
For Kerala, the southwest monsoon is the principal rainy season. However, October is an important rainfall month during the post-monsoon period, with the southern parts of the state being particularly affected. Historical IMD rainfall data show that northeast monsoon rainfall is still contributing to Kerala's annual rainfall and that rainfall activity is gradually decreasing through November and December.
Kerala Enters Northeast Monsoon Season After Rainfall Deficit
The forecast is significant and crucial because Kerala, like many other parts of the country, had a deficient southwest monsoon this year.
The southwest monsoon season ended on September 30 with India having a nearly 13 per cent lower rainfall deficit compared to the long-period average. The shortfall has intensified the focus on October to December rainfall outlook for south peninsular areas in which the northeast monsoon can account for a large portion of the annual rainfall for a significant part of the total rainfall.
The seasonal outlook of IMD suggests that most of the country could receive below-normal rainfall during the post-monsoon season. Southern parts of Peninsular India are expected to experience normal to above-normal rainfall conditions.
At the same time, the IMD's current forecast for Kerala indicates that rainfall activity is still possible in the state during the transition period. The Thiruvananthapuram Meteorological Centre has forecast isolated heavy rainfall in Kerala on October 1, 2, and 4, along with thunderstorms and lightning in some areas.
The transition from the southwest to the northeast monsoon does not mean that rainfall will be stopped in Kerala altogether. Weather systems can still produce showers during this period, and the larger seasonal circulation gradually shifts.
For southern Kerala, the latest outlook is to expect better rainfall in the coming months. Northern Kerala may not benefit as much, however, and meteorologists expect below-normal rainfall in the region.
The actual distribution of rainfall will depend significantly on the development and movement of low-pressure systems and cyclonic circulations, particularly over the Bay of Bengal. As such the seasonal forecast should be viewed as a broad outlook not a district-level forecast for every rainfall event.
