On the second Thursday of every month, NOAA issues its analysis of the status of ENSO. This includes determining the Alert System Status. NOAA describes their Report as “ENSO Alert System Status: Final La Niña Advisory”
If you read the fine print you can see that we are still in the transition. We have left La Niña but are not fully into ENSO Neutral. The rules seem to be that when you no longer meet the criteria for La Nina or El Nino, you are in ENSO Neutral even if the atmosphere has not fully transitioned to ENSO Neutral. This makes a lot of sense since in general, the atmosphere reacts to the ocean conditions rather than the ocean reacting to the atmosphere but it is not as clear cut as what I have just stated. But typically the reaction of the atmosphere lags the change in the ocean condition and the change in the atmosphere confirms that the change in the ocean will impact weather patterns.
Some of the models suggest a rapid change to El Nino during or after the Summer. It seems likely that the ENSO Neutral Phase will at the very least have an El Nino bias.
We have published a shorter version of our usual article since there is little disagreement that we are transitioning away from La Nina. It is also a bit too early to be confident that we will have an El Nino next winter. We need to get past the Spring Prediction Barrier (SPB) to be confident about having an El Nino soon.
The article includes a very interesting post from the ENSO Blog. It is worth reading. Among other things, it discusses the situation off of Peru which might increase the chances for an El Nino but it also is a warning as to some potentially problematic weather conditions for Peru.
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CLIMATE PREDICTION CENTER ENSO DISCUSSION
| The second paragraph is what is important: “The most recent CPC forecast indicates La Niña will persist into the Northern Hemisphere winter 2022-23, and then transition to ENSO-neutral in February-April 2023.” Later in the article, we discuss the situation in Peru which suggests that we have an additional reason to think that an El Nino is coming. There are also statistical reasons for thinking this might happen and this is discussed in the Emily Becker Blog which is provided later in this article. |
| 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. FMA stands for February/March/April. 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
And here is the forecast from last month
And here is the forecast from the prior month
| There is essentially no change for three months, especially the last two months. The chances of an El Nino seem to be increasing. |
What Does the NOAA Proprietary ENSO Model Forecast?
| This model shows the scatter in the forecasts. So it is difficult to have a lot of confidence in the ENSO situation later in 2023 other than it is not likely to be La Nina. The dark dashed line is the mean of the ensemble forecasts. NOAA tends to put more weight on the probability results that come out of their work with IRI but the two sets of results right now seem to be very similar. The above graphic does not auto-update but you can view and update by clicking HERE. But the current reading is what is relevant in terms of the NOAA ENSO analysis released on March 9, 2023. |
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And BOM? (Australian Bureau of Meteorology
| BOM has a different cut-off for La Nina than other meteorological agencies but they see a more rapid end (right now) of this La Nina. Based on their criteria, La Nina will end this month. Also, notice the movement toward El Nino. |
What do Other Meteorological Agencies Say
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| What I am showing here are NINO 3.4 forecasts for June of 2023. These are well-respected models. And using the U.S. threshold of -0.5 C they show that we will be in ENSO Neutral with an El Nino bias or in El Nino by June. Here is the link for this report and other ENSO information from BOM. |
But let us look out a little farther
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| By July the models are edging towards El Nino and using the U.S. criteria of +0.5C, many models are predicting El Nino by July. At any rate, the predictions are calling for ENSO Neutral with an El Nino Bias. Next month we should be more confident but still, we will not be past the Spring Prediction Barrier (SPB) |
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.
| Notice that La Nina conditions are gone along Equatorial Pacific. Notice the warm water off of Peru. Notice the cool water off of the North American West Coast clearly indicating PDO negative conditions while we have a steady stream of Atmospheric Rivers arriving. It is a big perplexing. |
Putting the historical information in motion (Updates can be found HERE.)
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 cool in the Nino 3.4 area especially South of the Equator. That is an oddity of this La Nina that is both westerly displaced and focused mostly south of the Equator. There is not much discussion of that and how that might impact our weather. It certainly explains why the NINO 3.4 Index is still in La Nina territory but warmer than last month.
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
| 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. |
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Are the changes significant? We need to look at additional information.
I abbreviated this section tonight because it seems that we can be confident that we have left La Nina 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. But the SOI has not yet quite fallen into the ENSO neutral range. NOAA (NWS CPS Div) prefers a slightly different index but it shows the same thing. |
This From the NOAA ENSO Blog is an interesting Post by Emily Becker
You can read her blog post by clicking HERE
The following is from her post and I found it very interesting.
The links are not active in the above but they can be accessed here, here, and here.
| The above is both interesting in terms of how it might predict an El Nino but also a warning as to some potentially problematic weather conditions for Peru. |
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 additional models
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| The IOD seems to possibly reoccur this summer. But it also is hard to predict. So I am not going to discuss that in detail tonight. If it is still in the forecast next month I will provide additional information on the possible impacts. |
| I hope you found this article interesting and useful. |
