weekly weather forecast for the period from 23/06/23 to 29/06/23 for India and Kerala.
General weekly observations and observation from 00.00 hrs on 22/06/23 to 23.59 hrs 22-06-23.
By Kerala Weatherman
In the previous week ended on 22nd June, 2023, the SWM has further advanced into more parts of sub-himalayan west Bengal, Jharkhand, some more parts if coastal Andhra Pradesh and Ratnagiri. However, the advance has been rather slow due to multiple factors. The main reason for the slow advance in coastal Maharashtra is the cyclone that moved in.
Another main reason for the slow advance of monsoon over major tracts of central India is the Eurasian mid-latitudinal Rossby wave trains that has gone weak. These Rossby wave trains have been researched a lot and studies have observed that these wave trains have an impact on the advance of the Indian monsoon into the central and north western parts of India by modulating the geopotential height anomalies lying between 40°E and 50°E. Upper level negative height anomalies create conditions favourable for rains and development of lows. It has a spillover effect on the depth of the moisture incursion from Arabian sea as well. This year this has been generally below average and remained positive and has now slowly started to pick up pieces.
By now the SWM should have covered MP, Maharashtra, Andhrapradesh, Telengana, Chatisgarh and Odisha and entire north- east. The remnants of the cyclone which hit Gujarat, last week has further moved eastward and is lying over east- central Uttarpradesh. The trough associated with it is running east to west along with a shear zone running north to south extending from east Uttarpradesh to Telengana, with its axis tilting south east with height. Meanwhile the upper air circulation over central BoB off the Odisha coast would hasten the monsoon advance into Odisha and Jhatkhand in the next 48 hrs.
In the previous week moderate to heavy monsoon-induced rains occurred in Nagaland, Arunachal Pradesh, lower Assam, Khasi hills, Tripura, sub- himalayan west Bengal, and isolated heavy rains over over Chennai, Puducherry, in Tamil Nadu.
In Kerala, the monsoon's performance continues to be dismal and below normal by more than 50% deficiency except in Kollam and Pathanamthitta where the deficiency is 30%. Situation is more grim in Kozhikode, Wayanad, and Kasargod where the deficiency is more than 70%.
Forecast:( Effective from 4:00 hrs from 23/06/23 to 23:59 hrs 29/06/23.
An upper air circulation which is lying off the Odisha coast in BoB would quicken the monsoon advance into central. India.
The upper air circulation over BoB off the Odisha coast is likely to become a monsoon low and move westwards towards south Bihar, Jharkhand, Vidarbha and interior Maharashtra, south Madhyapradesh, Telengana west Uttarpradesh, Delhi, with heavy rains or thundershowers in all of the above areas particularly in Raipur, Nagpur, Indore, Allahabad, Jamshedpur and Gwalior. Heavy rains are also likely over west Madhyaprdesh, Ahmedabad, and south Rajasthan as the upper air circulation is likely to move westwards.
As already predicted last week, the monsoon is likely to cover Maharashtra, Chatisgarh, Odisha, gangetic west Bengal , Bihar, Jharkhand, Telengana, remaining parts of Andhrapradesh, interior Maharastra, Vidarbha eastern Uttarpradesh, Uttrakhand and Madhyaprdesh by 24th June and the monsoon could hit Delhi around 28th June.
In Kerala the offshore western trough is likely to stabilize around 24th June and interior eastern areas can expect good rains only after that. As I mentioned in the beginning of this post, more moisture incursion in Arabian Sea is linked to position of the Walker circulation descent over the Iran Syria snd eastern Mediterranean belt.