ENSO Neutral Conditions Prevails With JAS 2017 ONI Index At -0.2ºC – La Nina Possible Earliest February 2018 Using NOAA Criteria

ENSO Status on 15th October 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 were based on a set of improved homogeneous historical SST analyses (Extended Reconstructed SST – ERSST.v4) and have now been updated to further improved homogeneous historical SST analyses (Extended Reconstructed SST – ERSST.v5). Explanation about ERSST.v5 is given here.

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.

Short lived La Nina ended with last 3-monthly season as NDJ 2017. Subsequently, Enso neutral conditions have prevailed thereafter.

Last five ONI Index are MAM 2017 +0.3ºC, AMJ 2017 +0.4ºC, MJJ 2017 +0.4ºC, JJA 2017 +0.1ºC and JAS 2017 -0.2ºC  (CPC/NOAA has it at -0.1°C ) hence the Nino 3.4 Region of Pacific Ocean continues to remain in ENSO Neutral zone.

 

Latest Oceanic Nino Index (ONI) Graph Showing Enso Neutral Event For Last Three 3- Monthly Seasons Ending September 2017

 

 

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. ERSST.v5

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

2015  10   29.07   26.75    2.32
2015  11   29.41   26.75    2.67
2015  12   29.26   26.65    2.60
2016   1   29.11   26.45    2.66
2016   2   29.00   26.66    2.34
2016   3   28.90   27.21    1.70
2016   4   28.73   27.73    0.99
2016   5   28.24   27.85    0.39
2016   6   27.70   27.65    0.05
2016   7   26.82   27.26   -0.44
2016   8   26.28   26.91   -0.63
2016   9   26.15   26.80   -0.65
2016  10   25.98   26.75   -0.78
2016  11   25.95   26.75   -0.80
2016  12   26.10   26.65   -0.55
2017   1   26.12   26.45   -0.33
2017   2   26.67   26.66    0.01
2017   3   27.31   27.21    0.11
2017   4   28.03   27.73    0.29
2017   5   28.29   27.85    0.44
2017   6   28.05   27.65    0.39
2017   7   27.53   27.26    0.27
2017   8   26.69   26.91   -0.22
2017   9   26.30   26.80   -0.50

 

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 8th October is +9.1 (90-day value +6.6), having passed into the La Niña value range within the last week.

The latest 30-day Southern Oscillation Index (SOI) on 14th October 2017 is +8.5 which is in the La Nina zone.

 

 

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.

 

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

 

 

30 Days average SOI was +6.16 at the end of September 2017 and +9.79 on 14th October 2017 as per The Long Paddock – Queensland Government.

 

Summary by: Climate Prediction Center / NCEP  Dated 9th October 2017

ENSO Alert System Status: La Niña Watch

ENSO-Neutral conditions are present.*
Equatorial sea surface temperatures (SSTs) are near-to-below average across the central and eastern Pacific Ocean.

There is an increasing chance(~55%-60%) of La Niña during the Northern Hemisphere fall and winter 2017-18.*

* 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


EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC 
DISCUSSION issued by CLIMATE PREDICTION CENTER/NCEP/NWS and the International Research Institute for Climate and Society

12 October 2017

ENSO Alert System Status: La Niña Watch

Synopsis: La Niña conditions are favored (~55-65%) during the Northern Hemisphere fall and
winter 2017-18.

As per BOM -Australia 10th October 2017

Weaker trade winds stall cooling in tropical Pacific – ENSO Outlook Inactive:

All earlier updates are listed below:

Click here for Update “Theoretically El Nino Not Possible During 2017”

Click here for Update “Theoretically El Nino Not Possible During The Indian Southwest Monsoon 2017”

Click here for Update “Full Fledged El Nino Not Possible During The Indian Southwest Monsoon 2017”

Click here for Update “ENSO Neutral Conditions At End Of February 2017”

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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