Arabian Sea Monsoon To Lose Steam By June 4, Bay Of Bengal To The Rescue?

MAY 30, 2017, TUESDAY

Putting it in a nutshell, the Arabian Sea wing of the monsoon is going to lose some of its stamina because of the upper air cyclonic circulation/weak 'low' that will form off Goa coast on June 3-4. The hope of revival lies on the Bay of Bengal low pressure system/depression that will form off the Andhra Pradesh coast on June 7-8.

Cyclone Mora has been a knight in shining armour for the Indian rainy season. It will push monsoon into Indian northeast along with its Kerala debut. It has energised the Arabian Sea which is about to go hammer and tongs into Kerala today, coastal Karnataka tomorrow, and Goa on Thursday. Expect a very wet Kerala today.

As we said monsoon in its youthful vigour will reach Goa by June 2. Then the problem starts. The weak low pressure system that will form off the Goa coast. Now this system is going to gather a lot of monsoon's rain clouds/thunderstorms and take it for a ride to central Arabian Sea away from the Indian mainland. And the 'low' will go phut mid sea.

Even if the 'low' does not form, indications are the Arabian Sea branch of monsoon is set to lose momentum after June 5. Because the massive clusters of thunderstorms that will form off Goa on June 3-4 will drift aimlessly back into sea.

Hence do not expect a tumultuous entry of the monsoon into Mumbai. It will be more low key with a depleted monsoon trying to do its best. Expect monsoon reaching Mumbai by June 8-9. Poor Gujarat, Rajasthan will have to wait. 

Despite that good rains are expected in Vidarbha, Madhya Maharashtra, Telangana and Andhra Pradesh in early June. Meanwhile rainfall activity in Kerala, Karnataka will continue to remain vigorous.

All hopes lie on the Bay of Bengal after Arabian Sea loses steam on June 4. The Bay will oblige with a big rainmaker low pressure system/depression off the Andhra Pradesh coast on June 8, 2017. Where it will go is not certain at this stage. After an Andhra landfall it could swing north towards Chattisgarh/Bihar/Jharkhand. Or it go northwest towards Telangana,Madhya Pradesh. If it moves roughly in a westerly direction Mumbai/Gujarat could see nirvana.

All hopes on the Bay of Bengal system now. The Arabian Sea stream of monsoon is expected to revive after June 8.

In fact, putting it bluntly, the Arabian Sea branch of monsoon will get stuck near Goa after June 3-4. Till how long it is hard to say now. All the rain north of that latitude (Vidarbha, Madhya Maharashtra, Telangana) will be fed by the moisture coming from the Bay of Bengal. 

Rainfall Forecast Till May 30, 2016, In South Asia

MAY 29, 2016

Below is the rainfall forecast map for India, Pakistan, Bangladesh and Oman. It is valid till May 30, 2016, 1800 GMT. In other words, where will it rain in the next 48 hours?

Bangladesh will receive the heaviest falls. More than 5 inches in some parts. So will isolated parts in Sri Lanka.

Indian north eastern states too will record 1-2 inches. Especially in some parts of Assam and Tripura. More than 1 inch expected in Kerala. Karnataka and Telangana too will receive showers. 

Isolated showers in rest of the country except the northwest of India.

Indian Monsoon 2016 To Rev Up In Early June

MAY 28, 2016

Mumbai will receive upto 4-5 inches of rain by June 12, 2016. Hardly a sign of a delayed weak monsoon. Though the Indian Meteorological Department has warned that the onset over Kerala might be delayed, global forecast models say though monsoon activity may be subdued in the last days of May, things will begin to change by June 5.

Monsoon will gather momentum as it will clamber up the Indian west coast. Mumbai will receive its first heavy showers around June 10, 2016.

By that time rainfall will intensify over the states of Kerala, Karnataka, Andhra Pradesh, southern Maharashtra and Telangana. 

Gujarat will start receiving increased pre-monsoon showers. As will Madhya Pradesh. In fact looking at the rain forecast map below only Rajasthan will remain dry by June 13, 2016.

One can say that rainfall activity is going to accelerate in the second week of June.

The rain forecast map above shows the total precipitation from now till June 13, 2016. The figures are in inches.

Above map shows the average monsoon rainfall received by different regions of India.

Above map shows the progress of monsoon 2016 till May 27.