El Nino Ends & First Enso Neutral Thresh Hold Established End Of June 2024 – Full Fledged La Nina As Per NOAA Criteria Not Expected During Indian South West Monsoon 2024
Enso Status on 04th July 2024
Ashok Patel’s Analysis & Commentary :
ONI Data has been obtained from CPC – NWS – NOAA available here
The current forecast and analysis clearly indicates that the First ENSO Neutral thresh hold has been established at the end of June 2024, thereby ending the 2023-24 El Nino. The ONI has dropped to +0.4°C for AMJ2024 season. ENSO Neutral conditions expected to continue for couple of 3 monthly seasons. To be classified as A Full fledged La Nina episode characterized by a negative ONI less than or equal to -0.5ºC and these thresholds must be exceeded for a period of at least 5 consecutive overlapping 3-month seasons. Hence La Nina cannot be established during the Indian South West Monsoon season that ends at the end of September 2024.
Indian Monsoon & Enso relationship for India:
Based on earlier more than 100 years weather Data for Indian Summer Monsoon, The Average Rainfall in an El Nino years is 94% of LPA while in La Nina Years it has been 106 % of LPA for the whole country. El Nino or La Nina may affect the Monsoon differently for different Regions of India and warrants research for concrete co-relations for each region of India if any.
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).
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.
The Climate Prediction Center (CPC) is a United States Federal Agency that is one of the NECP, which are a part of the NOAA
Latest Oceanic Nino Index Graph Shows El Nino Has Ended With Enso Neutral Thresh Hold Established At The End Of June 2024
The Table below shows the monthly SST of Nino3.4 Region and the Climate adjusted normal SST and SST anomaly from February 2023. Climate Base 1991-2020. ERSST.v5
Period Nino3.4 ClimAdjust YR MON Temp.ºC Temp.ºC ANOM ºC 2023 2 26.30 26.76 -0.46 2023 3 27.19 27.29 -0.11 2023 4 27.96 27.83 0.14 2023 5 28.40 27.94 0.46 2023 6 28.57 27.73 0.84 2023 7 28.31 27.29 1.02 2023 8 28.21 26.86 1.35 2023 9 28.32 26.72 1.60 2023 10 28.44 26.72 1.72 2023 11 28.72 26.70 2.02 2023 12 28.63 26.60 2.02 2024 1 28.37 26.55 1.82 2024 2 28.28 26.76 1.52 2024 3 28.42 27.29 1.12 2024 4 28.60 27.83 0.78 2024 5 28.17 27.94 0.24 2024 6 27.89 27.73 0.16
Indications and analysis of various International Weather/Climate agencies monitoring Enso conditions is depicted hereunder:
Summary by: Climate Prediction Center / NCEP Dated 2nd July 2024
ENSO Alert System Status: Final El Niño Advisory / La Niña Watch
ENSO-neutral conditions are present.*
Equatorial sea surface temperatures (SSTs) are above average in the West Central Pacific Ocean, near average in the east-central Pacific Ocean, and below-average in the far eastern Pacific Ocean.
La Niña is favored to develop during July-September (65% chance) and persist into the Northern Hemisphere winter 2024-25 (85% chance during NovemberJanuary).*
Note: 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.
Recent (preliminary) Southern Oscillation Index values as per The Long Paddock – Queensland Government.
30 Days average SOI was -4.89 at the end of June 2024 and was -1.86 on 4th July 2024 as per The Long Paddock – Queensland Government and 90 Days average SOI was -1.15 on 4th July 2024.
Southern Oscillation Index
As per BOM, Australia
The 30-day Southern Oscillation Index (SOI) for the period ending 30th June 2024 was -3.1 and was -0.5 on 2nd July 2024 and is in the neutral area.
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.
As per BOM – Australia 25th June 2024
Neutral ENSO and IOD conditions continue
The El Niño–Southern Oscillation (ENSO) is currently neutral.
Sea surface temperatures (SSTs) in the central Pacific have been cooling since December 2023. This surface cooling is supported by a cooler than average sub-surface in the central and eastern Pacific. During June, the rate of cooling has decreased. Cloud and surface pressure patterns are currently ENSO-neutral.
Climate models suggest that SSTs in the central tropical Pacific are likely to continue to cool for at least the next 2 months. Four of 7 models suggest SSTs are likely to remain at neutral ENSO levels, and the remaining 3 suggest the possibility of SSTs at La Niña levels (below −0.8 °C) from September.
The Bureau’s ENSO Outlook is at La Niña Watch due to early signs that an event may form in the Pacific Ocean later in the year. A La Niña Watch does not guarantee La Niña development, only that there is about an equal chance of either ENSO neutral or a La Niña developing. Early signs of La Niña have limited relevance to mainland Australia and are better reflections of conditions in the tropical Pacific.
Note: All Seasons mentioned by BOM are with respect to Southern Hemisphere.
Ashok Patel’s Analysis In Sanj Samachar Daily Dated 5th July 2024
