|Real-time SOI Data|
Numerical data from here and values are calculated using the 1887-1989 base period. This information is usually updated every weekday at 2:00pm (AEST), public holidays excluded.
|Date||Pressure at Tahiti (hPa)||Pressure at Darwin (hPa)||Daily value||30-day average SOI||90-day average SOI|
|2-Jun-2020||1015.15||1014.15||-2.04 (-11.67)||2.54 (-0.31)||-1.19 (-0.12)|
|1-Jun-2020||1017.01||1014.35||9.63 (-10.38)||2.85 (+0.19)||-1.07 (+0.09)|
|31-May-2020||1018.69||1014.55||20.01 (+2.22)||2.66 (+0.67)||-1.16 (+0.31)|
|30-May-2020||1018.55||1014.70||17.79 (+8.89)||1.99 (+0.58)||-1.47 (+0.39)|
|29-May-2020||1017.14||1014.45||8.90 (+7.35)||1.41 (+0.08)||-1.86 (+0.28)|
|28-May-2020||1015.88||1014.15||1.55 (+6.66)||1.33 (-0.06)||-2.14 (-0.01)|
|27-May-2020||1014.86||1014.00||-5.11 (+1.23)||1.39 (-0.21)||-2.13 (-0.23)|
|26-May-2020||1015.25||1014.55||-6.34 (-2.76)||1.60 (+0.04)||-1.90 (-0.25)|
|25-May-2020||1015.86||1014.80||-3.58 (+10.50)||1.56 (+/-0.00)||-1.65 (-0.18)|
|24-May-2020||1014.49||1014.80||-14.08 (-9.66)||1.56 (-0.47)||-1.47 (-0.23)|
|23-May-2020||1014.65||1013.70||-4.42 (-9.57)||2.03 (-0.21)||-1.24 (-0.11)|
|22-May-2020||1014.55||1012.35||5.15 (-5.82)||2.24 (+0.26)||-1.13 (-0.01)|
|21-May-2020||1013.46||1010.50||10.97 (+17.54)||1.98 (+0.36)||-1.12 (+/-0.00)|
|20-May-2020||1011.07||1010.40||-6.57 (+2.14)||1.62 (-0.49)||-1.12 (-0.12)|
|19-May-2020||1010.59||1010.20||-8.71 (-8.88)||2.11 (-0.79)||-1.00 (+0.08)|
|18-May-2020||1011.55||1010.00||0.17 (-11.34)||2.90 (+0.18)||-1.08 (+0.20)|
|17-May-2020||1013.38||1010.35||11.51 (-1.15)||2.72 (+1.00)||-1.28 (+0.33)|
|16-May-2020||1013.38||1010.20||12.66 (+13.56)||1.72 (+0.98)||-1.61 (+0.34)|
|15-May-2020||1013.21||1011.80||-0.90 (-9.8)||0.74 (+0.15)||-1.95 (+0.24)|
|14-May-2020||1014.74||1012.05||8.90 (-6.36)||0.59 (+0.05)||-2.19 (+0.29)|
|13-May-2020||1015.42||1011.90||15.26 (+11.64)||0.54 (-0.04)||-2.48 (+0.30)|
|12-May-2020||1014.55||1012.55||3.62 (+1.92)||0.58 (-0.4)||-2.78 (+0.14)|
|11-May-2020||1014.00||1012.25||1.70 (-0.85)||0.98 (-0.12)||-2.92 (-0.01)|
|10-May-2020||1013.96||1012.10||2.55 (-7.89)||1.10 (+0.15)||-2.91 (-0.08)|
|9-May-2020||1014.69||1011.80||10.44 (+5.06)||0.95 (+0.30)||-2.83 (+0.08)|
|8-May-2020||1014.33||1012.10||5.38 (+16.62)||0.65 (-0.04)||-2.91 (+0.02)|
|7-May-2020||1012.61||1012.55||-11.24 (-1.07)||0.69 (-0.1)||-2.93 (-0.12)|
|6-May-2020||1012.50||1012.30||-10.17 (-8.43)||0.79 (+/-0.00)||-2.81 (-0.11)|
|5-May-2020||1013.75||1012.45||-1.74 (-6.74)||0.79 (-0.09)||-2.70 (-0.09)|
|ENSO Wrap Up (Source: here)|
Issued on 26 May 2020
Tropical Pacific cools; negative Indian Ocean Dipole possible in 2020
The El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) remain neutral. While neutral ENSO is likely for the southern hemisphere winter, some model outlooks suggest a La Niña-like state will develop in the tropical Pacific Ocean during spring. Most models suggest a negative IOD will develop in the Indian Ocean from mid-winter, but model skill is low at this time of year.
The IOD is currently neutral. Most international climate models surveyed by the Bureau suggest the development of a negative IOD from the middle of the southern hemisphere winter. However, each of the models show a broad spread of likely scenarios between the neutral IOD and negative IOD range, and more recent model outlooks having slightly lower likelihoods of negative IOD. Accuracy of IOD forecasts is low for forecasts made during autumn, with accuracy improving in winter. A negative IOD typically brings above average winter–spring rainfall to southern Australia.
Key indicators of ENSO, such as the Southern Oscillation Index (SOI), trade winds, cloudiness near the Date Line and sea surface temperatures in the tropical Pacific Ocean, generally persist at neutral ENSO levels. However, sea surface temperatures across the tropical Pacific Ocean have cooled over the past several weeks. This has been supported by recent cooling of tropical Pacific sub-surface temperatures.
International climate models surveyed by the Bureau indicate that ENSO is likely to stay neutral through the southern hemisphere winter. However, by early-to-mid spring, three models of the eight models currently reach or exceed La Niña levels. Like model outlooks for the IOD, ENSO predictions made during autumn tend to have lower accuracy than predictions made at other times of the year. This is because development of both ENSO and the IOD have greater sensitivity to random weather factors at this time.
The Bureau's ENSO Outlook is currently at INACTIVE. However, if recent cooling at both the surface and beneath the surface of the tropical Pacific Ocean persists, and any more models suggest La Niña-like conditions in spring, the ENSO Outlook will shift to La Niña WATCH.
The Southern Annular Mode (SAM) is currently positive and forecast to remain positive for the coming two weeks. However, it isn't expected to have a significant effect on rainfall during this time due to interactions with other climate drivers and local weather conditions.
The 30-day Southern Oscillation Index (SOI) for the 30 days ending 24 May was +1.8. The 90-day value was −2.3. Both values are well within the ENSO neutral range.
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.
Sea surface temperatures (SSTs) for the week ending 24 May have cooled compared to two weeks ago. Cooling has now been observed across the central and eastern tropical Pacific for the past 5 weeks. Ocean temperatures are now cooler than average in parts of the eastern half of the equatorial Pacific Ocean, while some parts of the far east and far west of the equatorial Pacific remain warmer than average. Much of the central tropical Pacific SSTs are close to average for this time of the year.
SSTs remain slightly warmer than average around parts of Australia. SSTs are warmer than average around northwest Western Australia, and along parts of the east coast of Australia.
The latest values of the three key NINO indices in the tropical Pacific for the week ending 24 May were: NINO3 −0.2 °C, NINO3.4 −0.3 °C and NINO4 +0.1 °C. All NINO indices have cooled over the past fortnight, with NINO3 and NINO3.4 cooling by a significant amount (0.4 °C and 0.5 °C respectively).
While most of the eight international climate models surveyed by the Bureau indicate central tropical Pacific sea surface temperatures in the NINO3.4 region will remain at ENSO-neutral levels through the southern hemisphere winter, two models exceed the La Niña threshold during September, and another model approaches the threshold in October.
ENSO predictions made during autumn tend to have lower accuracy than predictions made at other times of the year. This means that ENSO forecasts made during autumn should be used with some caution, with accuracy increasing for ENSO forecasts made during winter.
ENSO events — El Niño or La Niña — typically begin to develop during autumn, before strengthening in winter/spring. The Bureau will continue to closely monitor the potential for either to develop this year.
Last Accessed: Tue Jun 02 2020 16:22:08 HKT
Last Modified: Wed Jul 24 2019