More El Niño thoughts
November 27, 2023
Here is a look at the latest model forecast strength and duration for this El Niño event. Focus on the mean forecast bar graph on the bottom of the charts, as it is the most responsible estimate of strength and duration:
As you can see, the event peaks from December-February, and then starts to weaken. Will this event be gone by the spring? I don’t see that happening. Will it be weakening considerably by the spring? Yes, I see that happening…
What about the analogs? The best fit analog years from the past are very tough to come up with, because we are dealing with a strong east-based El Niño and a very negative/cold PDO. See the current PDO graph below:
We also have what is called a positive Indian Ocean Dipole…
The years that have had a positive IOD, a strong east-based El Niño, and a negative PDO are very limited…pretty much non-existent. However, the following graphic shows just the correlation with a positive IOD and a strong east-based El Niño. The following graphics show the precipitation anomalies and the temperature anomalies that occurred during the years that matched up. Plus, you will see years listed multiple times…that is due to those years having more weight than others. The time frame runs from December through April…
There are some dry signals in the Pacific Northwest and parts of the Northern Rockies/Plains, and Ohio Valley. Otherwise, a lot of the country ended up wetter than average. The southwest part of the country was colder than average and the north/northeast ended up warmer than average. Now, out of all those years…1972-73 was still my favorite analog of the bunch. I have talked about that for quite some time, but here is a refresher on what it looked like from December – April of that winter/spring.
It may be tough to get cold and stay as cold as it was in 1972-73, but the overall storm track across a large part of the country looks pretty active. While it isn’t the best model out there due to it overdoing things, the CFS model does have some takeaways about the pattern. See the precipitation anomaly forecast below:
February – April:
April – June:
While the CFS model does have a tendency to be too wet or too dry, the overall flavor may not be that far off. While we may not technically be in an El Niño after April, we may still be benefitting from the residual impact of it.
While the back half of 2024 is more uncertain, I do believe that we will revert back to a La Niña. Historically, the PDO usually will moderate or even turn positive when an El Niño occurs. That has not been the case, and likely won’t be the case going forward. Because of this, La Niña can more easily redevelop after the El Niño episode has ended. Historically, La Niña produces a decent monsoon for the southwest part of the country, and favors wetter than average conditions in the fall/winter, for the Pacific Northwest, Northern Rockies/Plains, while drying things out in the Desert Southwest, and the Western/Southern Plains.
I know we are talking about things a long way out there in time, but I know you are interested…and I wanted to share my thoughts. If you have questions, please let me know…