Tuesday, March 27, 2012

March has meant 7,000 weather records broken in the U.S...see International Page.
Global Warming Hysteria Page Updated..

An Early Prelude to the Monsoon Watch Series has become necassary as the La-Nina has ended a little faster than expected. 
MW Series will start around 10th April.

The 2011–12 La Niña event has ended:

This past week an active Madden-Julian Oscillation (MJO) moved into the western Pacific, cloudiness increased and easterly wind anomalies along the equator decreased. As a result, all key indicators of La Niña are now within neutral thresholds. 

With key indicators returning to neutral (neither El Niño nor La Niña) levels, the La-Nina is over !

The 2011–12 La Niña decline has been fairly typical, with a peak in January and a return to neutral conditions by early summer (or spring).

Sea surface temperatures across the equatorial Pacific Ocean have generally warmed (though only slightly) compared to those of two weeks ago. All three NINO indices monitored have warmed in the past fortnight. 
NINO3 −0.1 +0.1 0.2 °C warmer
NINO3.4 −0.4 −0.3 0.1 °C warmer
NINO4 −0.5 −0.3 0.2 °C warmer

The SST anomaly map for the week ending 26th March shows mostly near-normal sea-surface temperatures in the equatorial Pacific, with some residual cool anomalies across the central equatorial Pacific.

The Indian Ocean Dipole is now showing a "trend" towards a positive movement. Current SST show leaning more towards a +ve IOD. In fact it is not -ve at all.
A fully developed +ve IOD has proven to be good for the SWM in the Indian Sub Continent.

Likewise, Southern Oscillation Index (SOI) have also returned to near-normal values for this time of year. The 30-day SOI to 25 March is +7.1  
The Southern Oscillation Index (SOI) rose early in the last fortnight before holding around +7 for the past week, remaining within values indicative of neutral ENSO conditions. 
The SOI has remained within neutral values since mid to late February. The latest (25 March) 30-day SOI value is +7.1.

Sustained positive values of the SOI above +8 may indicate a La Niña event, while sustained negative values below −8 may indicate an El Niño event. Values of between about +8 and −8 generally indicate neutral conditions. 
It has been below the threshold of +8 since 19 February. 

The demise of the La Niña means the chances of a "super" SWM has ended. But, neutrality can indicate a normal (not super) SWM. 
While sea surface temperatures around the sub-continent remain coolerr than normal, there remains a chance of normal (or even slightly above normal) rainfall over the Indian regions.

As of today (according to me), The above two SST parameters (ENSO and IOD) indicate a normal SWM. But do not forget, there are another 6/7 parameters like the cyclone season in South Indian Ocean, the Mascrene Highs, April/May heat in central and NW India, cross equatorial winds, pressure gradients etc that will determine the strength and arrival date of the SWM. 

Excerpts from Aust.Bur.of Met,, Jamstec, Unysis and Vagaries'compilations.


Rajan Alexander said...

Hi Rajesh. Couldn't reply earlier was sick. Not blogging for quite awhile.

Can you elaborate "A fully developed +ve IOD has proven to be good for the SWM in the Indian Sub Continent" Which years?

Model forecasts show weakly positive IOD. What's its implications

Pradeep said...


I can help you with the data you require. Pls see the below link.


Rajesh said...

Rajan: Did not know you were not well. Hope you're ok now.
IOD is subjectively new, and older archives of SST have not been marked with the IOD Label.
But recent "rainy years" and drought years of last 20 years tally to the extent of around 80%, I think.

Pradeep has suggested a very useful and helpful link..Thanks Pradeep, I'll surely read through the site.

Rainfall for the period 1-3-2023 to 31-5-2023

    Number of Districts with above normal rainfall         :    504     Number of Districts with below normal rainfall         :    209     ...