Lightly Edited at 9:39 p.m. Saturday, May 12, 2023 to add some details that I was too exhausted to sort out when I published early this morning.
On the second Thursday of every month, NOAA issues its analysis of the status of ENSO. This includes determining the Alert System Status. NOAA again describes their Report as “ENSO Alert System Status: El Nino Watch”
There is not much doubt that we will have an El Nino.
From the NOAA Analysis:
The combination of a forecasted third westerly wind event in mid-late May, and high levels of above-average oceanic heat content, means that a potentially significant El Niño is on the horizon. While at least a weak El Niño is likely, the range of possibilities at the end of the year (November-January) include a 80% chance of at least a moderate El Niño (Niño-3.4 greater than or equal to 1.0°C) to a ~55% chance of a strong El Niño (Niño-3.4 greater than or equal to 1.5°C). It is still possible the tropical atmosphere does not couple with the ocean, and El Niño fails to materialize (5-10% chance).
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CLIMATE PREDICTION CENTER ENSO DISCUSSION
| The second paragraph is what is important:
The most recent IRI plume also indicates El Niño is likely to form during the May-July season and persist into the winter. The combination of a forecasted third westerly wind event in mid-late May, and high levels of above-average oceanic heat content, means that a potentially significant El Niño is on the horizon. While at least a weak El Niño is likely, the range of possibilities at the end of the year (November-January) include a 80% chance of at least a moderate El Niño (Niño-3.4 greater than or equal to 1.0°C) to a ~55% chance of a strong El Niño (Niño-3.4 greater than or equal to 1.5°C). It is still possible the tropical atmosphere does not couple with the ocean, and El Niño fails to materialize (5-10% chance). In summary, a transition from ENSO-neutral is expected in the next couple of months, with a greater than 90% chance of El Niño persisting into the Northern Hemisphere winter. [ Editors Note: the 5 to 10% chance that this El Nino will not materialize is good practice but I think it is very unlikely that this will happen] |
We now provide additional detail.
CPC Probability Distribution
Here are the new forecast probabilities. This information in the past has been released twice a month and the first release is based on a survey of Meteorologists, the second is based on model results. The probabilities are for three-month periods e.g. AMJ stands for April/May/June. The first forecast is used to develop the Seasonal Outlook which will be issued next Thursday so that is what I am focusing on.
Here is the current release
| You can clearly see the change in the probabilities from AMJ to MJJ. I pay a lot of attention to the middle month in the three-month period so J or June is what is being forecast. But this is just the forecast for the Nino 3.4 Index. So the impact on U.S. and World weather will take a little time to show up. The forecast does not extend beyond DJF but one does not see any tail-off in the probabilities for El Nino conditions in the Eastern Pacific. |
And here is the forecast from last month
And back in January
| In January we had a hint that we might have an El Nino. Now the probabilities of an El Nino are very high and the real question is how strong will it be. |
What Does the NOAA Proprietary ENSO Model Forecast?
| This model shows the scatter in the forecasts but the scatter is much less than last month. The dark dashed line is the mean of the ensemble forecasts. If you want to see an updated version you can view an updated version by clicking HERE. But the current reading is what is relevant in terms of the NOAA ENSO analysis released on May 11, 2023. It does seem to show a peak in OND and a slight tailing off after that. Something to watch. |
View of other Meteorological Agencies
They all agree that there will be an El Nino but there is a range of opinions on how strong it will be and I do not have forecasts of that out far enough in the future to be helpful at this point in time.
Looking at Actual Current Conditions.
NOAA reports some derived data that describes the current situation and a forecast. But what if we want to form our own opinion? After all, meteorologists are looking at the actual current situation and making predictions.
This shows the current actual situation for the surface of oceans. To update this graphic click HERE.
| You can already see the warm tongue of water extending from Ecuador and Peru. We still see the PDO Neg Pattern in the Northern Pacific. The warm water off of West Africa might be important re the Hurricane Season. |
Where is ENSO Measured?
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| You can mentally superimpose the Nino 3.4 area shown encompassing part of the yellow and part of the red areas in the above map and you can see that it is pretty much neutral in the Nino 3.4 area especially South of the Equator. However in the Nino 3 and Nino 1+2 Areas the water is very warm.-But it is still under the El Nino Threshold in Nino 3.4 but that will probably change very soon as the warm tongue extends to the west. From the NOAA Diagnostic Discussion: “Low-level wind anomalies were westerly during mid-April before switching back to easterly by the end of the month” . |
Putting the historical information in motion. Updates can be found HERE. but should not be needed.
Now we look at the below surface temperature anomalies. Mapping the details. (Cross-Section along the Equator). The data is a five-day average centered on the date shown.
And Last Month
And the prior month
And the prior month
And the prior month
| We now see that the warm water at depth has undercut the cool water in the Eastern Pacific and indeed there is warm water at the surface off of Peru. But in the Nino 3.4 area it is warm but not very warm. You can see that the process really speeded up this last month. It is like to continue to progress into El Nino Conditions. |
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Here is an animation of the above.
You should not need to update this since it seems to auto-update but HERE is the link.
Water temperatures in the top 300 meters (1,000 feet) of the tropical Pacific Ocean compared to the 1991–2020 average in February–April 2023. NOAA Climate.gov animation, based on data from NOAA’s Climate Prediction Center.
Here is another way of looking at it.
| Here we integrate the temperature of the layers to get the total heat anomaly for the different layers down to 300 meters. You can see how it went from colder than -0.5C to between -.05 C and +o.5C to now above +0.5C. But it is the surface temperature that counts and the area measured here is a little different than the Nino 3.4 area. So we can not translate this into weather but it shows how the structure of the subsurface has changed, I could probably provide a more complete explanation of the interconnection of the surface to the subsurface (direction of causality) during the different phases of ENSO but this provides a useful metric to describe how things have changed. |
Kelvin Wave: One explanation of the recent rapid change in the situation are Oceanic Kelvin Waves.
| This type of Kelvin Wave is one of the mechanisms for the warm water in the IndoPacific WarmPool to move to the east. This is a Hovmöller diagram It is sort of like a plotter graph as it shows the earlier time periods at the top and the most recent at the bottom. It is used a lot in meteorology. Notice the two dashed lines towards the bottom. It is showing that there was a weak downwelling Kelvin Wave that was not followed by an upwelling phase but instead by a subsequent and stronger downwelling phase. That broke the back of the La Nina. The MJO may have contributed to initiating the Kelvin Wave. Three consecutive years of La Nina caused the IndoPacific WarmPool to increase and begin to spread out. This makes it easier for this kind of Kelvin Wave to get started. That is why no one phase of ENSO can last indefinitely but it was a surprise to have three La Nina Winters in a row. [NOAA mentions a third earlier downwelling Kelvin Wave that did not seem to amount to anything at the time. Perhaps they are forecasting another Kelvin Wave very soon. The above is from the Monday ENSO Diagnostic so is probably a week old. ] |
Are the changes sufficient to move not just from La Nina to ENSO Neutral but all the way to El Nino?
We need to look at additional information.
I abbreviated this section because it seems that we can be confident that we have left or will soon leave ENSO Neutral conditions in terms of the sea surface temperatures in the Nino 3.4 measurement area but is the atmosphere responding?
| The SOI has been falling which is consistent with the end of La Nina and is now in the ENSO neutral range: approaching but not quite reaching the El Nino Range. So that is why I conclude that the 5% to 10% skepticism of NOAA is appropriate but I think not likely to happen. But there is always the question of exactly when it happens. |
Interesting article from the NOAA ENSO Blog
You can read the article by clicking HERE
What about the Indian Ocean Dipole (IOD)?
| The index is calculated as the monthly difference between the western (10°S-10°N, 50°-70°E) (WTIO) and eastern Indian Ocean (10°S-0°, 90°-108°E) (SETIO) sea surface temperature departures from average. |
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Australia BOM IOD forecast
And looking at some other models as well
| The IOD seems to possibly reoccur this summer. It may be bad news for Australia. It will impact all nations where their weather is impacted by the Indian Ocean. But the impacts will vary based on latitude. We should see this in the JAMSTEC World forecast which I plan to publish Saturday or Sunday.
Here is what the BOM says about the situation,
Here is what JAMSTEC says
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| I hope you found this article interesting and useful. |
