DJF 2017 ONI Index At -0.4ºC, Marginally Lower Than La Nina Threshhold – ENSO Neutral Conditions Over Nino 3.4 Region Of Pacific Ocean

ENSO Status on 6th March 2017

The ONI is based on SST departures from average in the Niño 3.4 region, and is a principal measure for monitoring, assessing, and predicting ENSO. Defined as the three-month running-mean SST departures in the Niño 3.4 region. Departures are based on a set of improved homogeneous historical SST analyses (Extended Reconstructed SST – ERSST.v4). The SST reconstruction methodology is described in Huang et al., 2015, J. Climate, vol. 28, 911-930.
CPC uses current Climatology based on 1986-2015 which has been changed late last year from base years 1981-2010. Explanation about Climatology base years change is given here.

NOAA Operational Definitions for El Niño and La Niña, 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.

CPC considers El Niño or La Niña conditions to occur when the monthly Niño3.4 OISST departures meet or exceed +/- 0.5ºC along with consistent atmospheric features. These anomalies must also be forecast to persist for 3 consecutive months.

Full fledged La Nina event had been confirmed at the end of January 2017 relying on the official NOAA definition for La Nina, because there were now five 3-monthly seasons JAS 2016 at -0.6ºC, ASO 2016 at -0.7ºC, SON 2016 at -0.8ºC, OND 2016 at -0.8ºC, NDJ 2017 at -0.7ºC having La Nina threshold. There is a variation of ONI index by 0.1 C for ASO 2016 where CPC reports -0.8ºC at the source cited.

ONI Index for DJF 2017 is -0.4ºC which is marginally lower than the La Nina thresh hold and hence now the Nino 3.4 Region of Pacific Ocean has entered ENSO Neutral zone.

Latest Oceanic Nino Index (ONI) Graph Showing Commencement Of Enso Neutral Event at end of February 2017

 

ONI_DJF2017

 

The Table below shows the monthly SST of Nino3.4 Region and the Climate adjusted normal SST and SST anomaly for last two years. Climate Base 1986-2015.

Period    Nino3.4 ClimAdjust
YR   MON  Temp.ºC Temp.ºC ANOM ºC


2015   2   27.25   26.80    0.45
2015   3   27.79   27.32    0.47
2015   4   28.59   27.86    0.73
2015   5   28.83   27.98    0.85
2015   6   28.70   27.76    0.94
2015   7   28.50   27.37    1.13
2015   8   28.47   27.02    1.45
2015   9   28.62   26.94    1.68
2015  10   28.86   26.91    1.95
2015  11   29.14   26.88    2.25
2015  12   29.04   26.80    2.24
2016   1   28.94   26.61    2.33
2016   2   28.89   26.80    2.09
2016   3   28.87   27.32    1.55
2016   4   28.97   27.86    1.11
2016   5   28.60   27.98    0.62
2016   6   27.82   27.76    0.06
2016   7   26.99   27.37   -0.38
2016   8   26.39   27.02   -0.63
2016   9   26.22   26.94   -0.72
2016  10   26.06   26.91   -0.84
2016  11   25.96   26.88   -0.93
2016  12   26.08   26.80   -0.72
2017   1   26.25   26.61   -0.37
2017   2   26.65   26.80   -0.15

 

CPC considers El Niño or La Niña conditions to occur when the monthly Niño3.4 OISST departures meet or exceed +/- 0.5°C along with consistent atmospheric features. These anomalies must also be forecast to persist for 3 consecutive months.

 

Southern Oscillation Index

 

As per BOM, Australia:

The 30-day Southern Oscillation Index (SOI) to 26 February is −1.2 (90 day value +0.4). SOI values have generally been within the neutral range since mid-October.

The latest 30-day Southern Oscillation Index (SOI) on 3rd February 2017 is -2.0 within the neutral ENSO range.

Sustained positive values of the SOI above +7 typically indicate La Niña while sustained negative values below −7 typically indicate El Niño. Values between about +7 and −7 generally indicate neutral conditions.

 soi30_030317

 

SOI Monthly graph up to February 2017 as per The Long Paddock – Queensland Government.

2017_February_SOI

 

SOI was -2.24 at the end of February 2017 and -2.36 on 2nd March 2017 as per The Long Paddock – Queensland Government.

 

Summary by: Climate Prediction Center / NCEP  Dated 27th February 2017

ENSO Alert System Status: Final La Niña Advisory ENSO-neutral conditions are present.* Equatorial sea surface temperatures (SSTs) are near-average across the central and east-central Pacific. They are above-average in the eastern Pacific Ocean. ENSO-neutral conditions have returned and are favored to continue through at least the Northern Hemisphere spring 2017.*
* Note: These statements are updated once a month (2nd Thursday of each month) in association with the ENSO Diagnostics Discussion, which can be found by clicking  here

As per BOM -Australia 28th February 2017

El Niño WATCH: likelihood of El Niño in 2017 increases

All earlier updates are listed below:

Click here for Update “2016/17 Qualifies As A La Nina Event

Click here for Update “Enso Neutral Conditions At End Of October 2016

Click here for Update “Full Fledged La Nina Not Possible During 2016

Click here for Update “Demise Of El Nino Brings ENSO Neutral Conditions At End Of July 2016”

Click here for Update “Moderate El Nino Persists Till End Of May 2016”

Click here for Update “Strong El Nino Persists Till April 2016”

Click here for Update “NOAA ERSST.v4 & ERSST.v3b & Effects On ENSO Events”

Click here for Update “Yet A Weak El Nino – 6th June  2105”

Click here for Update “El Nino Update – 5th May 2015”

Click here for Update “Weak El Nino Develops March 2015”

Click here for Update “El Nino Status – 6th March 2015”

Click here for Update “El Nino Status – 7th February 2015”

Click here for Update “El Nino Status – 6th January 2015”

Click here for Update “El Nino Status 6th November 2014”

 

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