EasternLI

Some thoughts from the MJO desk weekly update from yesterday.

Intuitively, makes sense and I agree. The MC is a tricky area for convection though and can play games sometimes. We'll see what modeling trends decide to do with it over the coming days. I suspect it will make it as well, but we'll see.

The AAM is set for a rapid rise towards neutral. After having fallen to strongly negative values. The cause of this will be the addition of momentum from the upcoming pacific jet extention in conjunction with the MJO event. How this plays out should have an effect further down the road. The MJO is modeled differently on different systems currently. The EPS AI ensembles have been pretty robust with it. Ideally, we'd like to see the negative AAM anomalies propagate poleward to 60N over time. If so, there could be some actual potential for early winter northern blocking. Towards December perhaps. I'll be interested to see how this plays out..

By which metric is the Pacific warm pool warmer than last year at this time? NOAA keeps a dataset on that area here : https://psl.noaa.gov/data/correlation/pacwarm.data 2024 0.592 0.659 0.500 0.591 0.604 0.605 0.655 0.635 0.640 0.654 0.658 0.492 2025 0.536 0.459 0.448 0.433 0.473 0.382 0.472 0.483 0.458 That data doesn't agree with the assertion... As per their defined area, here are last year versus this year for visual comparison. Last year: This year: The negative IOD certainly front and center in this part of the world, as has been discussed in this thread. No issue with that whatsoever. However, the tropical western pacific is actually not as warm as it was at this time last year. Neither are the waters in the vicinity of Indonesia. NOAA data reflects this year being less impressive as well. So by which metrics is this years west pacific much warmer than last year? I'm not seeing it and I disagree.

This year is seemingly lining up to be an interesting case to watch regarding all of this. The paper did mention the addition of enso forcing alters things. Sometimes drastically. However over the course of the last 30 days, it does appear to be a stand out feature on the VP200 charts and OLR charts. I didn't notice any recent years, when looking back through that data, looking quite like this. So certainly a very valid feature to monitor.

Yeah, like I said, barring some other overpowering influences.

The negative IOD is kind of interesting. This is a good article about the IOD and it's effects. The relationship is modeled to weaken over time in the future with some changes to the sst gradients. However, for now and when you eliminate other factors. -IOD seemingly favors -NAO in and of itself if it were the dominating feature. Climate change alters the Indian Ocean Dipole and weakens its North Atlantic teleconnection https://www.nature.com/articles/s43247-025-02131-5

The funny part to me is that 2013 actually did do that. Similar timing. There seems to be this notion in here that there was this static warm pool in the NE Pacific for months on end that year. When that was not the case from what I've been seeing looking back at the data.

Modeled sst forecasts aside. It's at least slightly interesting to compare the north Pacific layout currently emerging this year, in early September, to the same time period from 2013.

I'm kinda impressed with the way this MJO is progressing. Plus it's of the slow moving variety. Which is good in this case because those are the more likely versions to affect the circulation. Velocity potential tells a better story then the RMM charts. It's interesting too, that models continually have tried to kill this wave in extended ranges. Since November really. Yet it still continues on. These are both from the GEFS. Check out where we were and compare it to where we are headed. Effectively muting the MC region, while allowing the western hemisphere to be more dominant in the forecast period. Cold enso base state is also is also identifiable on these but not overpowering everything like our most recent La ninas have. Top image I have saved from the 12/12 00z GEFS. With a forecast ending at 00z today, the 29th. Bottom image is last nights 00z GEFS.

Great post. I've done a fair amount of reading on this topic over the last several years. I think your thoughts are right on the mark as far as lining up with said reading. One thing I remember seeing, and I don't remember where, is that if one is looking for an ssw to deliver a colder pattern. There's a higher probability of that occurring from one that initiated during an already colder pattern. Which sounds like it lines up with your thinking on the phenomenon and kinda makes sense to me.

The PDO should continue to climb too, with the progged pattern. Which is interesting. This is a 5 day mean from the 12z eps.

Impressive poleward ridging from the 18z GEFS heading into the heart of January. It's interesting also, to see the eps weeklies now weakening the SPV pretty substantially by mid January. Which would be consistent with an mjo 7 response.