Wednesday, July 14, 2010

As one reader has mentioned, the rainfall in this strategic region is very poor. Mahableshwar, the "water reservoir" of Maharashtra, is very important as it originates 5 rivers from its catchment. The most prominent, The Krishna river flows from the Mahbleshwar catchment down through the plains of Satara dist. rest of Maharashtra, thru A.P. into the Bay. The entire south Maharashtra and Ksishne Basin region of A.P. depends on the rains in this station.
This year, 2010, the station has recieved 890 mms till date, 14th. July, against a normal of 1920 mms required till date.
Last 3 years, end July totals are:
2006: 4733 mms
2007: 2118 mms,
2008: 1200 mms,
2009: 2662 mms.

The driest July was in 1899, with1084 mms during the month.
The highest ever seasonal rain was 10221 mms (1896)
and the lowest 3545 mms (1899).

But the rains are scanty in the ghats, and even though nearby Pune (60 kms away, but on the plains) has recieved 325 (+116) mms, and Satara, 60 kms away in the plains recieved 269 mms (_33). But,the actual rain days are less.
Rain days diagram of Pune and Mumbai (Coastal city) for rainy days comparison).
Another station, Lonavala, is also weak in rains this year.
As on end June, the rainfall there was 437 mms.

Last few years comparison of June shows the situation there.
2008: 1187 mms,
2009: 175 mms.
2010: 437 mms

What actually brings rains to the western ghats are depressions from the bay, not off shore troughs. Normally there should be at least 1 in June and 2/3 in July.This year, we have had none, and got 2 weak systems, that too UACs. Surprisingly, depressions are in drought this year, as are Pacific typhoons !


Atul said...

Thanks for the information :).
I have few questions

Do we foresee any depression from the bay by end of this month ?

Also is it possible to cover deficit rain in Mahabaleshwar and Lonavala in rest of monsoon season?

What could be reason for not forming depression in the bay?

Also what are the average number of depressions from the bay in August and Sept?

Anonymous said...

Thunderstorms have been forecasted for the Mumbai region by the BBC Weather site for tomorrow. This could be due to the UAC over Chattisgarh which is likely to move West. If we do get heavy thunderstorms in Mumbai it would be one of the rare instances of Thunderstorms in Mumbai so late after the Monsoon has set over the city. In any case by the personal records that I keep this Monsoon has had the one of the most 'Thunder heard' days so far in the recent times

rajesh said...

Sorry for replying late. I think personally, there will be a depression/low from the bay by 20th. though, as i have written in my blog, IMD had stated Friday (today).Reasons also have been given in the blog. I feel, one of the main reason is the lack of typhoons in the Pacific. My earlier year's archives give a detailed reasoning of this.Maybe a good Deep depression or two can make up for the lack of rains in the catchment.

I personaaly see the next "thunder occasion " in Mumbai when a low/depression becomes active. We generally, always get thunder after a break monsoon condition revives.
we've had thunder in July very often.

Anonymous said...

This is what the IMD bulletin of 15th 'Night' says:

•The axis of monsoon trough likely to shift slightly northwards from 18th onwards.
•No indication of major cyclonic genesis over Bay of Bengal during next 5 days.

We have technically not had the 'break monsoon' period as yet this Monsoon in Mumbai as it has rained practically everyday since the onset, although a few regions in the country could be experiencing very low monsoonal activity