Friday, March 18, 2011


The Sw Monsoon is now about 75 days away, and its about time to start analysing the important factor connected with it. The LA-Nina. Sure, it is one of the factors that will be considered when Vagaries starts with its annual ritual of the Monsoon Watch " series.

For the readers, information,, the Monsoon Watch will commence with its first article on 10th. April.

Today, just a brief write up with the latest on the La_Nina front.

The Pacific Ocean of the La-Nina region, has warmed up to aa certain extent . Upto last week, the warming was:
As of last week it was warmer by 0.6c in NINO3, 0.5c in NINO3.4 and 0.4c warmer in NINO4.
The actual SST anomaly was -0.5c,-1c and -1.3c in NINO3, NINO3.4 and NINO4 respectively.

However, in spite of this weakening of the La-Nina, the effects, atmospheric parameters, have not been as prominent. Meaning, trade winds (stronger than normal), cloudiness ( near the date-line continues to be strongly suppressed) and the Southern Oscillation Index (SOI). These remain consistent with a well developed LaNiña event.

The SOI as on 14th. March was +26, still posively strong. More of this in our Monsoon Watch, as, La-Nina will be one of the parameters. (Remember, El-Nino was a strong parameter in our previous MW).

The estimated life by IRI, of this event is shown in this histogram.

However, you can't be certain that the La Nina episode will end. The average of the models simulations just mildly crosses above the -0.5 °C threshold that defines the conditions.
In fact, the NOAA folks think that the ongoing La Nina episode will end and ENSO-neutral conditions will return by June 2011. That should still be enough for the ENSO cycle to negatively contribute to the global mean temperature throughout 2011, making it one of the cooler years.

2 comments:

Ganesh said...

Hi Rajesh,its amazing to see someone who keeps interest in weather and so knowledgeable.I too love tracking weather and glad that i found your blog.Keep posting!!

rajesh said...

Thanks Ganesh..since you track the weather too, your inputs for Vagaries are most welcome..and welcome to the Vagaries family..