( Continuation from..We have probably reached the peak...published on 28th January).
" In Meteorological terms, this El Nino is now in decline. But we cannot lower our guard, as it still quite strong and in humanitarian and economic terms, its impacts will continue for many months to come." ..WMO Secratary General Petterri Taalas.
A very straightforward and cautious statement.
The El Nino is surely on the wane. What we normally should observe initially is the Sea temperatures "below the surface'. If this lower "below sea level" waters start cooling, the cooler waters surface, and the sea surface temperatures drop in the wake of this process. Now, cooling sea water below surface are measured in the Eastern Pacific region.
However, Equatorial Pacific sea surface temperature anomalies (difference from normal) have cooled over the past fortnight. Actual temperature drop in Nino 3.4c is only 0.1c and
in Nino 3 it is 0.2c.
Since its the anomaly that has dropped, the El Nino levels remain at moderate to strong El Niño levels. So, the virtual disappearance of this El Nino phenomena is still a long time away. April /May/ June may see a transitional Neutral Stage of the ENSO.
In the January period, we generally see a variation and intra-seasonal variability in the atmosphere (wind and pressure). This directly affects the the Madden-Julian Oscillation (MJO) and OLR parameters. negative anomalies have been observed over the central and/or eastern Pacific.
Anomalous upper-level (200-hPa) easterlies were observed over most of the equatorial Pacific. Anomalous anti-cyclones straddled the equator.
SOI values cannot be considered as reliable during this ( January) period. Seasonal storm systems cause massive fluctuation, from -23 on 26th Jan.. to -9 on 14th February.
The ONI is based on SST departures from average in the Niño 3.4 region, and is important in monitoring and even forecasting the expected turn of the ENSO event.
Most recent ONI value is 2.3. ( +0.5 and over is El Nino; -0.5 and below indicates La Nina. But for a full fledged La Nina (or El Nino), it must be consistent for at least 5 overlapping seasons. So, a La Nina developing before August does not look possible.
Australian Bureau of Meteorology:- "Based on the 26 El Niño events since 1900, around 50% have been followed by a neutral year, and 40% have been followed by La Niña. International climate models suggest neutral is most likely for the second half of the year. However, La Niña in 2016 cannot be ruled out."
Vagaries would estimate, as stated earlier in its article, the El Nino effect on the Indian climate would wane and decline only after June 2016. This would mean a weak sluggish start to the South West Monsoon. The Monsoon gaining strength after July is possible, and may extend into October.
This would augur well for India, and would come as a relief after 2 consecutive drought years.
But, while determining the quantum of the 2016 Monsoon, we must understand and remember that ENSO is only 1 of the parameters. The IMD has 6 parameters to consider while giving its April forecast for the SWM. Gowarikar's method (still held in high esteem by Vagaries) has 16 parameters.
Next Part end of March.....