The 14-day observation of Solar Garbottam, having an impact on the rainfall season from June 21st to the end of December 2024, is given in the table below. Though the observation period started on 29th December when the Sun entered Purvashadha, I have come to an opinion that the observation period is relevant from the waxing phase of the month of Karthika as suggested by the Siddhasena school. It is because the onset of the SWM starts from the end of May, but the current model of Solar (Margazhi) Garbottam is relevant only from a month later. Good garbottam features seen from 25th to 28th December 2023 ensure that daily rainfall in Chennai would start before the date given in the table below.
A notable feature of this assessment is that from the 11th day of Garbottam onwards (8th Jan) there was no cloud movement during the daytime. Nighttime observation was impossible to do. So, I used satellite pictures to check the cloud movement at night from 8th January onwards. The prediction is based on those images.
The table shows rainfall in all months from June to the second week of December with continuous rainfall indicated in November.
A major feature of this garbottam was that it rained on three days of the Garbottam period, corresponding to the second fortnight of three months, namely, September, October and November. During the same days, there was cloudiness at night-time, which I could not observe with naked eyes but found out from the Satellite pictures provided by Mr. Balaji Thirugnanasambantham, a MTech student from BITS Pilani.
On 7th January, it rained, and it continued on the morning of 8th January too. The satellite picture provided by Balaji shows a heavy cluster of clouds over Chennai at pre-dawn. On physical observation, I found that it rained till 9 am on the 8th.
8th January pre-dawn – clouds over Chennai and rains till 9 am spoiled Garbottam.
This picture gave me confidence on the reliability of the satellite pictures for the night sky when physical observation is not possible. Nighttime observation is essential because last year I predicted deficient NEM on the basis of day time observation when there were no clouds. But the heavy rainfall in NEM to Chennai showed that it must have been triggered by night-time Garbottam. The above picture taken at pre-dawn looks reliable indicator for rains because I noticed rain since sun rise on that day.
Since the daytime of 8th, 9th and 10th January were almost blank indicating failure of NEM, I sought the maps and made my assessment based on the satellite pictures. My big thanks to Balaji for getting me the maps.
By the evening of 8th January, Chennai skies were covered with clouds. Heavy spread of clouds in South India shows good rains in South India which marred garbottam, but Chennai didn’t get rainfall in the evening. The clouds continued to hover over Chennai at night which made me expect rainfall in the corresponding period in November.
9th noon was cloudy both in naked eye observation and in the satellite map.
9th evening also showed Garbottam though to a lesser extent. Anyway, I assign rainfall in the corresponding period of November.
On the 10th pre-dawn time, the sky was cloudy sparingly over Chennai. There was fog till 7 am (naked eye observation). So, I marked rainfall in the corresponding period of November.
On 10th evening from 5 pm onwards, I noticed cloudiness which continued till 7 am on the 11th. The star Purvashadha was running then which favours rainfall.
Infact, the coastal stretch of Andhra and Bangalore are also showing a long patch of clouds indicating widespread rain in the second half of November. Chennai will be in the border of rainfall band at that time.
On the 11th pe-dawn time, a band of clouds had passed over Chennai indicating rainfall in the corresponding period in the beginning of December.
This lasted till 7 am only in naked eye observation. After that the sky had become clear over Chennai which can be seen in the satellite map too.
The corresponding date is December 11. There is no rainfall after December 11th.
But the overall picture is encouraging with regular rainfall to Chennai.
If not for the satellite maps, I would have ruled out rains during NEM for Chennai.
Last year’s bad judgment made me look for ways to find out nighttime Garbottam.
If this analysis proves true, we can safely depend on satellite pictures hereafter and not necessarily on physical observation.
In the next article, I will be posting the Daily Garbottam seen till the time of writing.
Jayasree's weather blog 
You must be logged in to post a comment.