Enso Neutral Conditions Prevails July 2018 – ONI Index is Just +0.1C For MJJ 2018 – East Pacific Is Colder Than Normal

Posted on11/08/201825/06/2023AuthorAshok Patel239 Comments

Enso Status on 11th August 2018

Enso Neutral Conditions Prevails July 2018

How ONI is determined:

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 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.

Last five ONI Index are JFM 2018 -0.8ºC, FMA 2018 -0.6ºC, MAM 2018 -0.4ºC, AMJ 2018 -0.1ºC and MJJ 2018 +0.1ºC. Latest Nino 3.4 SST is +0.17ºC and the calculated ONI MJJ 2018 is +0.1ºC, though positive but in neutral zone. Hence ENSO neutral conditions continues to exist.

La Nina event 2017-18 had officially ended at the end of April 2018 (FMA 2018). ENSO neutral conditions exists since then.

Latest Oceanic Nino Index Graph Shows ENSO Neutral Conditions Continues MJJ 2018 Season

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

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   26.68   26.66    0.02
2017   3   27.33   27.21    0.12
2017   4   28.04   27.73    0.30
2017   5   28.30   27.85    0.45
2017   6   28.06   27.65    0.41
2017   7   27.54   27.26    0.28
2017   8   26.70   26.91   -0.21
2017   9   26.29   26.80   -0.51
2017  10   26.15   26.75   -0.60
2017  11   25.74   26.75   -1.01
2017  12   25.62   26.65   -1.04
2018   1   25.58   26.45   -0.88
2018   2   25.98   26.66   -0.68
2018   3   26.50   27.21   -0.71
2018   4   27.32   27.73   -0.41
2018   5   27.74   27.85   -0.11
2018   6   27.76   27.65    0.13
2018   7   27.43   27.26    0.17

Southern Oscillation Index

As per BOM, Australia:

The 30-day Southern Oscillation Index (SOI) to 29 July was +2.2, and the 90-day SOI was −0.4. The SOI is +1.9 on 2nd August 2018 and has been within the neutral range since late April.

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

Recent (preliminary) Southern Oscillation Index values as per The Long Paddock – Queensland Government.

30 Days average SOI was +1.79 at the end of July 2018 and was +1.18 on 1st August 2018 as per The Long Paddock – Queensland Government and 90 Days average SOI was -0.68.

SOI Monthly graph up to July 2018 as per The Long Paddock – Queensland Government.

Summary by: Climate Prediction Center / NCEP Dated 6th August 2018

ENSO Alert System Status: El Niño Watch

ENSO-neutral conditions are present.*
Equatorial sea surface temperatures (SSTs) are near-to-above average across most of the Pacific Ocean.
ENSO-neutral is favored through Northern Hemisphere summer 2018, with the chance for El Niño increasing to about 65% during fall, and to about 70% during winter 2018-19.

* 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 31st July 2018

ENSO outlooks

Most of the eight surveyed international climate models predict warming of central equatorial Pacific sea surface temperatures (SSTs) is likely to resume over the coming months. Five of the eight models suggest El Niño thresholds are likely to be reached in spring, with six of eight models exceeding the El Niño threshold value during December.
(Note: winter/spring is with reference to Southern Hemisphere)

NINO3.4 SST plumes from POAMA forecasts, updated daily

Ashok Patel’s Analysis & Commentary :

Using NOAA Criteria, Enso Neutral conditions continue to prevail from May 2018 (MAM 2018) with the latest 3-monthly season MJJ 2018 at +0.1ºC

La Nina event 2017-18 had officially ended at the end of April 2018 (FMA 2018) as per NOAA criteria.

Last five ONI Index are JFM 2018 -0.8ºC, FMA 2018 -0.6ºC, MAM 2018 -0.4ºC, AMJ 2018 -0.1ºC and MJJ 2018 +0.1ºC. The last three 3-monthly seasonal ONI Index indicates Enso Neutral conditions continue to prevail from May 2018. July 2018 SST anomaly for Nino 3.4 for is +0.17ºC.

Hence, currently neither Nino 3.4 SST anomaly nor the last ONI index has even reached the El Nino thresh hold for single month or a single 3-monthly seasons respectively.

The last two Nino 3.4 SST anomaly are June at +0.13ºC and July at +0.17ºC. Possibility for First 3-monthly season to reach El Nino thresh hold requires the ONI reaches +0.5ºC from the current +0.1ºC level. Possibilty of El Nino thresh hold in August is very low since the chances of August Nino 3.4 SST anomaly crossing +1.0ºC at the end of August is dismally low.

Using NOAA criteria, a full-fledged El Nino event is rules out during the Indian Summer Monsoon, since there are now only two 3-monthly seasons left till end of September 2018, namely JJA 2018 & JAS 2018, and Indian Summer Monsoon normally comes to an end by then (September end). Full fledged El Nino requires El Nino thresh hold to continue for five consecutive 3-monthly seasons.

અશોક પટેલ નું તારણ અને વિશ્લેષણ :

NOAA માપદંડ મુજબ 2018 જુલાઈ આખર ના ENSO ન્યુટ્રલ સ્થિતિ ચાલુ રહી છે.

છેલ્લા પાંચ ત્રી-માસિક સીઝન નું ONI ઈન્ડેક્સ આ પ્રમાણે છે: JFM 2018 -0.8ºC and FMA 2018 -0.6ºC, MAM 2018 -0.4ºC, AMJ 2018 -0.1ºC અને MJJ 2018 +0.1ºC. છેલ્લું ત્રી-માસિક સીઝન MJJ 2018 નું ONI ઈન્ડેક્સ +0.1°C, એટલે NOAA માપદંડ મુજબ મે 2018 તેમજ જૂન 2018 ની જેમ જુલાઈ 2018 નું ONI ઈન્ડેક્સ Enso ન્યુટ્રલ ઝોન માં છે. જુલાઈ 2018 નું નિનો 3.4 નું SST ઍનોમલી 0.17ºC છે. અત્યાર સુધી એક પણ મહિના નું નિનો 3.4 નું SST ઍનોમલી કે છેલ્લું ONI ઈન્ડેક્સ એલ નિનો ના ઉંબરા સુધી પહોંચેલ નથી. છેલ્લા બે મહિના નું SST ઍનોમલી જૂન 2018 +0.13ºC અને જુલાઈ +0.17ºC છે . ઓગસ્ટ માસ ની આખર માં SST ઍનોમલી +1.0ºC થવાની શક્યતા હાલ નથી. માટે ઓગસ્ટ આખર સુધી માં નિનો 3.4 એલ નિનો ના ઉંબરા સુધી પહોંચશે નહિ. તેમજ ભારતીય ચોમાસા દરમિયાન NOAA ના માપદંડ મુજબ વિધિવત ‘એલ નિનો’ થવાની શક્યતા પણ નથી. કારણ એમ છે કે ભારત નું ચોમાસુ સપ્ટેમ્બર આખરે પૂરું થતું હોય છે અને હવે સપ્ટેમ્બર આખર સુધી ફક્ત 2 ત્રી-માસિક સીઝન બાકી છે, જે છે JJA 2018 & JAS 2018 અને એલ નિનો માટે ઓછા માં ઓછી 5 ત્રી-માસિક સીઝન જોઈએ.