Saturday, July 11, 2009

Its getting into the act now ! El Nino seems to be developing faster than expected.

US scientists say that the El Nino warming trend of the Pacific Ocean waters has returned, bringing with it almost certain changes in weather patterns around the world.
The El Nino climatological effect - the periodic warming of central and eastern tropical Pacific waters - occurs on average every two to five years and typically lasts about 12 months.
The US National Oceanic and Atmospheric Administration said the current El Nino was likely to develop further during the next several months, with additional strengthening possible and is expected to last through early 2010.

For us, in the sub continent, it is a certain El-Nino when the SOI, ( a difference in the pressures at Tahiti and Darwin) is -10. The latest figure has reched to -5.

The reason I am stressing on this now, is because, since the last 30 days, I see no proper system coming/developing for the Indian Sub Continent ( in the Bay, specially), in spite of several reputed forecasting agencies prophecising the same.

Today, 11th July, and yesterday, Rajasthan and parts of Punjab saw some rain. But, this was due to the interaction of the mentioned Easterlies with the Upper Air Circulation, now over M.P./Rajasthan. What I mean is , to get real Monsoon rains, meaningfull rains, we need a full scale system like a depression, at least. Till then how can such a big rain deficit (of the north/central/west) be wiped out ?

As of now, I do see any such system coming "in-situ" in the Bay till the 15th. The attached 825 hPa map shows the "UAC" in the west, another weak "UAC" over Bengal in the east, and the axis of the monsoon "line " joining the two. Rains are today seen along this axis line. With the fizzling out of the western UAC, I see the axis line shifting nortwards again. And diminishing the rains over the northern/central regions.
And the Arabian Sea low, seems to be a difficult proposition now. And if at all, it will too away to have any effect on India.

Mumbaites, my 4/5 days rain estimate will be over by Sunday evening. Expect less rains for next 4 days ( maybe 15-20 mms /day). And for Maharashtra, the winds rushing towards the Eastern Low, brought some rains (see map) last 2 days. Maybe lessening of precipitation next few days.
Gujarat, a day more of some rain, till the western low fizzles out. Maybe scanty rains next few days.

A fresh review, in a couple of days, may pop up some sudden surprises, hopefully.


Anonymous said...

Heavy rains have resumed in Mumbai from yesterday evening with very Gutsy winds. Is this because of the bay low? Which would be a bit surprising since the low is still over Northern Orrisa / W Bengal coasts and hasn't come inland. Mumbai generally gets a lot of rain when the low moves towards E - MP / Vidarbha.

Rajesh said...

Yes, you arecorrect.athats what I have mentioned in my next blog.

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