As monsoon is gradually activating in the Bay of Bengal heading towards India’s Sikkim, Nepal will likely to see arrival of monsson oon. According to Meteorological Forecasting Division, there will be partly to generally cloudy throughout the country. Isolated Brief rain or thundershowers likely to occur at some places in the country.
According to India’ weather Chnnel skymetweather.com, Northern Limit of Monsoon (NLM) continues to pass through Mangalore, Mysore, Salem, Cuddalore, Goalpara, Alipurduar, and Gangtok.
The humid winds from the Bay of Bengal are feeding moisture to the Northeast India. Thus, we expect moderate rains with one or two heavy spells in Manipur, Mizoram and Nagaland while, Scattered light to moderate rains will be seen in the remaining parts of Northeast India, Sub-Himalayan West Bengal and Sikkim. Light rains are expected at few places in Bihar which might give some relief from the hot weather conditions. Coastal Odisha might witness one or two intense spells of thundershowers.
Conditions are becoming favourable for further advancement of Southwest Monsoon into some more parts of Central Arabian Sea, Karnataka, some parts of south Konkan & Goa, Andhra Pradesh, remaining parts of Tamil Nadu, some more parts of West Bay of Bengal, remaining parts of Northeast India, Sub-Himalayan West Bengal and Sikkim and some parts of Odisha in the next three to four days.
An off-shore trough is extending from Maharashtra coast up to Karnataka coast and now we expect light to moderate rains with one or two heavy spells to occur over Kerala and Coastal Karnataka. A trough is also extending from Gangetic West Bengal up to North Coastal Odisha. It will help in enhancing the rainfall activities over Coastal Andhra Pradesh. Light rains might occur over Telangana and Rayalaseema while isolated rains will be seen over South Interior Karnataka and Tamil Nadu.
In Central India, a trough is extending from Central Uttar Pradesh up to Southwest Madhya Pradesh. Scattered rain and thundershower activities are possible in West Madhya Pradesh, adjoining parts of Southeast Rajasthan and Gujarat region. Konkan and Goa would witness good rain and thundershower activities. Also, one or two short spells of thundershowers are possible in Chhattisgarh with isolated rains possible over rest of Madhya Pradesh and Vidarbha.
Finally, up in the North, a Cyclonic Circulation is over Central Uttar Pradesh. Therefore, scattered rains are possible in East and Central Uttar Pradesh. Isolated dust storm is a possibility in Punjab, Haryana and Rajasthan. Light rain is expected at few places in Jammu and Kashmir, Himachal Pradesh and Uttarakhand. Delhi will witness partly cloudy sky and temperatures are expected to increase marginally.
The systems in Bay of Bengal along with Monsoon Trough are main drivers of the advancement of Monsoon, also being major contributors of core Monsoon rains.
There are depressions that form in the Bay of Bengal, Arabian Sea and in land, known as insitu. Bay of Bengal has more frequent systems that the Arabian Sea with the ratio being 4:1. As the Monsoon months progress, systems increase with maximum systems forming in September, and lowest in June.
The insitu systems also intensify on land under the influence of a westerly trough or Western Disturbance with their ratio in terms of Bay being 1:6.
Monsoon depressions have a typical characteristic in terms of weather distribution. Southern half sees more rains as compared to the northern with the most amount of weather being in the southwest region.
June depressions which are responsible for advancement and progress of Monsoon, are different than the systems that develop during the thick of Monsoon. Withdrawal month systems are also different from typical Monsoon systems.
The systems in the Bay form in the Northern parts or as we can call it, the head Bay in the beginning, and as the season progresses, shift slightly south over the northern parts of Central Bay of Bengal.
June systems in Bay have coastline on either side, and do not have much pace due to which these systems do not intensify much. The systems that develop later in the core Monsoon months get more oceanic area making them more significant and helping them in gaining strength.
The tracks of the systems also varies, and with the Northern Limit of Monsoon being dictated by the track and movement of the Monsoon system developing in June. Similarly, the withdrawal line is dictated by the systems’ track forming in September.
Every month, on an average at least two systems are seen in the Bay of Bengal and anything less than two systems were deficit in terms of Monsoon systems for Bay.
However, this year, the first Circulation has come up in the Bay of Bengal which is taking shape now. The system is now likely to form a Low Pressure Area on June 20. While this system will remain feeble but will be responsible for carrying Monsoon further into central, eastern as well as southern parts.