Most of the agencies monitoring El Nino have been forecasting every month from the beginning of 2014 that an El Nino would begin in the next two months. The year 2014 has completed without a full fledged El Nino. Only two consecutive overlapping 3-month seasons SON and OND have had ONI index equal to or above +0.5ºC thresh hold till end of 2014. SON 2014= +0.5ºC and OND 2014 = +0.7ºC
At the end of January 2015 we have one more overlapping 3-month season NDJ with ONI index equal to or above +0.5ºC thresh hold. NDJ 2015 ONI=0.7ºC. This makes total of three consecutive overlapping 3-month seasons SON, OND & NDJ with ONI index equal to or above +0.5ºC thresh hold till end of January 2015. SON 2014= +0.5ºC and OND 2014 = +0.7ºC and NDJ 2015 ONI=0.7ºC.
El Niño: characterized by a positive ONI greater than or equal to +0.5ºC.
La Niña: characterized by a negative ONI less than or equal to -0.5ºC.
By historical standards, to be classified as a full-fledged El Niño or La Niña episode, these thresholds must be exceeded for a period of at least 5 consecutive overlapping 3-month seasons.
Southern Oscillation Index
The Southern Oscillation Index (SOI) has remained relatively stable over the past fortnight, hovering around the boundary of neutral and El Niño values. The latest 30-day SOI value from BOM-Australian Government for period ending 1st February is −8.3.
SOI Monthly graph from The Long Paddock – Queensland Government
Outlook:
Although the SST has declined during the last month, the ONI Index for the next seasonal 3 months DJF is expected to equal or exceed the thresh hold of +0.5ºC because the Nino 3-4 SST for December is +0.75ºC & January is 0.54ºC so even if Nino 3-4 SST for February is only +0.10ºC, the fourth consecutive seasonal period the conditions for ONI Index of +0.5ºC or higher will be fulfilled.
Hypothetically if Nino 3-4 SST for March 2015 manages to stay reasonable positive, then the next 3 monthly seasonal period JFM should also fulfill the ONI of +0.5ºC for declaring a full fledged El Nino.
One more interesting record would be that if indeed a full fledged El Nino develops within two months, this EL Nino would be the only EL nino to have been declared at the end of March from 1950 on wards.
Note: Most International agencies have now eased their forecast for chances for a full fledged El Nino currently.
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