EasternLI

Yeah agree.

Looks like this latest WWB was the strongest of the summer.

Yeah, thought that was odd too.

CPC MJO update from today confirming the mid month constructive interference that was targeted and verified. Culminating in the current WWB activity. Also the difficulty in identifying the MJO due to the strong Nino. The propagation though the western hemisphere was making me think a recurving typhoon was possible as a consequence of that. But that looks like a failed idea on most recent guidance. So still waiting on that. A selection of the bullet points from the update below: • The strong El Niño continues to be the major influence on anomalous rainfall and tropical cyclone (TC) development throughout the global tropics. • During mid-August, the MJO began to constructively interfere with the strong El Niño similar to what occurred in July. • The MJO is expected to propagate eastward over the Western Hemisphere during late August and then shift back to the Indian Ocean by early September. • The strong El Niño and a favorable MJO are likely to result in multiple TCs developing over the East Pacific through the end of August. However, a robust monsoon response in the Desert Southwest of the U.S. is not expected. • High shear, associated with El Niño, will continue to inhibit TC formation in the Main Development Region of the Atlantic. • A wave-1 pattern persisted in the global upper-level velocity potential fields predominantly tied to the strong El Niño. • Although the strong El Niño is the main influence on the velocity potential anomalies, the MJO recently shifted east across the Pacific which led to the largest anomalous upper-level divergence in the past six months. • As the enhanced phase of MJO constructively interfered with the El Niño base state during early to mid-August, the RMM index exited the unit circle in Phase 6. • This behavior of the RMM based signal is very similar to the path taken earlier this summer. • Positive SST anomalies continue over the central and eastern Pacific, with anomalies now at 1.8°C across NINO 3.4. NINO 4 has gradually cooled during the past several weeks, associated with increased cloudiness over the region. • Remarkably strong positive subsurface temperature anomalies (> 2.5°C) persist across the Eastern Pacific. • Negative subsurface temperature anomalies have expanded eastward to near the Date Line. • A majority of GEFS and ECMWF ensemble members depict the RMM index remaining over phases 6 and 7 due to the strong El Niño. It is difficult to discern the MJO evolution during the next month.

This current WWB looking pretty impressive. This isn't even the anomalies, these are the actual zonal winds.

Well there you go. The current WWB is another record breaking one. As was suspected would be the case with the latest MJO assist.

Yeah, that's a totally valid point. Any records from that long ago are questionable at best. I know there are reanalysis methods but still. Wish there was a better normalized way to look at it. Not as tied to temperature anomalies. Especially if rising global temperatures are a concern. I get that RONI is attempting to do that, but not sure how I feel about that yet either. What I do know is that out of the entire JMA archive of VP 200 anomalies. This event (the current 30 day mean obs posted below) is already now more impressive looking than anything in their entire record. Which goes back to the 40's. That includes 15-16, 97-98, 82-83, 72-73 or anything else. Actually everything else in that data. At least as it stands right now and during this part of the year. That, to me, is making this event stand out much more than any temp anomalies ever could. It's fascinating to watch something extreme like this unfold. As an aside, I do not have high hopes for winter here locally. Very strong enso either + or - generally sucks historically here where I am. I will firmly believe that until proven otherwise because I've already lived through it. Extreme events are always interesting though, and this el nino is definitely that.

These are big claims, don't see why not though TBH.

Does the AAO signal anything to us (NH)? I don't remember. I want to say no, but I feel like I've heard that it did somewhere. Just wondering because it's been very positive through most of our summer. Which is the SH winter. Even getting above 4SD for a bit at the tail end of June.

MJO is really booking it this year. I've read WQBO can speed it up too, so that's a little interesting. But man this thing is really flying. I feel like all that's going to do is constructively interfere with this el nino more often. Seems like this would just encourage the nino to take center stage even more so. Not that it needs that..

Well, maybe there are... then again maybe there aren't lol, but if we can get something like the 12z AIFS-ENS below. It would probably keep going the right direction. Start seeing this kind of GOA low on a regular basis would do wonders for the eastern portion of it. Do that plus get some tropical cyclones to take a bite out of that north Pacific warmth that has pooled there from the persistent ridging in that area. Combined, that would go a long way towards transforming that index. As a side note, that's part of the reason I would like to see a couple recurving typhoons through that region. Some guidance is hinting at maybe there finally being some potential for that too as we close out the month. I'm keeping an eye on that. Could have a shot there for one.

Jamstec updated for August.

I've learned a great deal about the MJO over the years. Because I view it as an important phenomenon but also didn't like relying on others for real updates. I wanted to know more than what the simple phase space diagrams can offer. This is a challenging year to be trying to follow the MJO. Need to be able to dig into it a little deeper to really see what's going on with it. Or to even see it at all. Like I mentioned earlier in the thread, the RMM charts can be misleading sometimes. This year is one of those times. The following from the CPC global tropics discussion also points that out, updated yesterday: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/ghaz/index.php "The Madden Julian Oscillation (MJO) has continued a pattern of constructive and destructive interference with the El Nino low-frequency base state over the past few months as the El Nino signal has strengthened. Over the past week, the RMM-based index showed the MJO intensifying as it moved through the Maritime Continent and into the Western Pacific (Phase 6) where it once again began to constructively interfere with El Nino. The MJO signal has now reached a stronger amplitude than the last time it emerged in Phase 6, back in late June when the El Nino signal was superimposed on the enhanced phase of the MJO. Upper-level velocity potential anomalies over the past week show a weak MJO signal farther west moving through the Indian Ocean, suggesting that the strong El Nino background state may be distorting the position of the MJO in RMM-space. With this ongoing constructive interference with the El Nino base state, RMM-based forecasts keep the MJO signal over the Western Pacific (Phase 6) for the next two weeks. Although consistent with phasing, models are split on the amplitude of the signal, with the ECMWF and CFS predicting a robust MJO over the next week and the GEFS maintaining a weaker signal. During Weeks 2 and 3, the GEFS begins to amplify the signal and maintains a strong MJO, while the ECMWF shows a weakening signal moving into the unit circle. By the end of week-3, the models agree on the signal moving into Phase 7. Over the next four weeks, the upper-level velocity potential anomalies show a stationary wave-1 pattern with the enhanced divergence envelope remaining over the Eastern Pacific. However, eastward propagation of the MJO signal can be seen in the wave filtering, showing the signal propagating from the Indian Ocean into the far Eastern Pacific."

Looks like this would be an off the scale WWB over the next couple of days according to the 12z GEFS. Has another big one later in the month too.

Top of the scale WWB on the 00z EPS.

Another curious detail about this year. Decided to look at the AO data for those other strong and super nino's. In the Jun-Jul period it looks like they all average negative for that period. All of them. This year it was positive. Not sure what that ultimately means but thought it was interesting.

Yeah, will be fascinating to see how the north Pacific responds through this event. Given the deep -PDO state of the atmosphere it is encountering. El nino is certainly ramping up. AAM about to take another step up from the upcoming MJO cycling and associated WWB. Getting impressive too with a forecast mean remaining above 3 SD. If we look at the world view. We can see the SH jet has been, and is forecast to continue to be very impressive. Along with El nino conditions really getting comfortable in the tropics now as of late. A little bit of El nino's influence appears to be trickling into the NH now as well. The forecast has that continuing also and increasingly so as we get towards the tail end of the month. So envision a slow take over, if you will. As we go through the fall. That's my guess. Will be interesting to see if that's how it plays out. I think that makes some sense given the underlying resistance in the Pacific. I personally doubt that resistance will ultimately be too much for this event. Not one of this magnitude, this one's a behemoth. But that is a battle worth watching in the north Pacific for sure. Would still love to see a recurving typhoon or 2 as well but there's time for that.

Granted this is from the July run. But the Jamstec wasn't far off from a CFS or Cansips situation either. Will be interesting to see when it updates. Although, I'm on the same page with bluewave on these seasonal model runs. They're geared towards enso more than anything else. That's where they hold the most skill. So you often see straight enso composites from them the further you go out in time and they can miss things in the mid latitudes. They're simply not tuned for that. Interesting to see some of these solutions regardless.

I mean, the MJO is currently crossing the MC. Yet, suppression is remaining firmly in place through that. It's not everyday that happens. It's still slated to interact with the Nino right after mid month. Another big WWB is likely inbound.

Man this El Nino is getting really impressive already. VP 200 charts are in beast mode. These are 30 day means! Obs! Just blows 2023 out of the water. Starting to look more impressive vs 2015 even TBH. At least as far as compared to this same time period. Action centers even looking like pure textbook Nino too. Which is pretty cool to see on a chart. This thing is a powerhouse, no question. MC is even shut down.

You know what, yeah. I've been interested in mid month for something like that for a bit. Maybe that's still on track. I didn't even realize it at the time either, but all the models do have this wave train too. Will certainly be interesting to follow.

Maybe the NH is starting to come around slowly. If we use the JMA composite for warm enso in August. We see this wave train from the Pacific through NA. Then looking over the AIFS-ensembles 12z run, here is a 5 day mean. There is a wave train visible in the Pacific through NA similar to the one shown on the composite.

I think you're both right. The SST PDO is a reflection of a propensity of the atmosphere to favor that state. Whether that is positive or negative. There are also far longer term oscillations known, such as the IPO. Which can have a period of 40-60 years. I personally believe the IPO explains the long term negative period we have witnessed. There are also short term (+PDO) events within a long term -IPO, and vice versa. Although they are shorter lived than they otherwise would be when they oppose the IPO. With the + or - phase dominant over that entire period depending on the IPO. We are currently in a negative phase. We have been since the late 1990's. For one reason or another, the atmosphere has been predisposed towards -PDO thanks to that. I actually think this explains quite well a year like 23-24(-IPO). Where you can get an el nino with a -PDO. Or on the flip side, a year like 95-96(+IPO). Where you can get a la nina with a +PDO. The EOF of a +IPO is posted below followed by a few studies. Pay extra attention to the second one, as it relates to the North Pacific. Powerful enso events have the potential to flip the Pacific. As the la nina following 97-98 is attributed to beginning this current negative IPO phase. So we're closing in on 30 years now. In this context, I find an inbound record breaking el nino all the more interesting. There's a shot at flipping the longer term Pacific to something more like the following EOF. Instead of the opposite, which we've become accustomed to. The record wildfires in Australia several years ago also may have acted to extend this negative period beyond what it otherwise would have been. By driving the triple dip la nina of the 2020's. In fact it's been postulated that had those fires not happened. 2015-16 likely would have begun the transition to +IPO. The influence of the Interdecadal Pacific Oscillation on Temperature and Precipitation over the Globe https://link.springer.com/article/10.1007/s00382-015-2500-x "Since 1920, there are two warm (1924–1944 and 1977–1998) and two cold (1945–1976 and 1999–present) IPO phases, whose change is associated with abrupt shifts in North Pacific sea level pressure (SLP) and contrasting anomaly patterns in T and P and atmospheric circulation over the eastern and western Pacific." Statistical relationships between the Interdecadal Pacific Oscillation and El Niño–Southern Oscillation https://link.springer.com/article/10.1007/s00382-023-07035-8 " While the spatial SST patterns that represent the IPO and ENSO are similar, the IPO is meridionally broader in the central to eastern Pacific, which may be caused by a lagged relationship with low-frequency SST variability in the equatorial Pacific. In addition, North Pacific SST anomalies of opposite sign to the tropical Pacific SST anomalies is a unique feature of the IPO that cannot be explained by decadal ENSO variability. This suggests a clear IPO and ENSO relationship, but also independence in some of the IPO’s characteristics." The role of interannual ENSO events in decadal timescale transitions of the Interdecadal Pacific Oscillation https://link.springer.com/article/10.1007/s00382-021-05784-y "A long pre-industrial control run with CESM1 is analyzed to show that there is a greater chance of ENSO activity to contribute to an IPO transition when off-equatorial western Pacific Ocean heat content reaches either a maximum (for El Niño to contribute to a transition to positive IPO) or minimum (for La Niña to contribute to a transition to negative IPO) as seen in observations." 2019-2020 Australian bushfire smoke, multi-year La Niña, and implications for the Interdecadal Pacific Oscillation (IPO) https://www.nature.com/articles/s41612-025-01204-8

The H300 PDO or upper air PDO index came in at -2.03 for July. The last time this index was positive at all was 2015-16. The last time it was +1 or greater was 1997-98. 2026 1 -1.61 2026 2 -1.58 2026 3 -1.73 2026 4 -1.70 2026 5 -1.93 2026 6 -2.05 2026 7 -2.03