bluewave

Everyone has their own subjective likes and dislikes when it comes to the weather. I liked cooler and wetter in the summer when it used to keep the big beach crowds away from Long Beach. Since finding parking spaces was always a challenge there. So 1996 and 2009 are two of my favorite summers living in Long Beach. I didn’t mind having several days which were compete washouts since all the perfect days in the 70s and low 80s made up for it.

There are a few ways of looking at this. If you use a linear model, then you would be correct. But a non-linear process involving threshold temperarures of marine heatwaves potentially driving the forcing leading to that record breaking ridge would be a different case. The ridge out West was much stronger from November to March this year than the similar weak La Niña in 1995-1996. Such an increase could be the result SST forcing thresholds being met and the pattern becoming much more amplified and locking in over a longer duration. So rather than a gradual increase in temperatures and 500mb ridging, the warmer background pattern resulted in more of a jump. The CONUS was actually slightly colder in 1995-1996 instead of the warmest November to March on record in 2025-2026. There wasn’t the extended record warmth out West over the same period back in 1995-1996. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101499 Circus Tents, Convective Thresholds, and the Non-Linear Climate Response to Tropical SSTs Using model simulations, we demonstrate that the climate response to localized tropical sea surface temperature (SST) perturbations exhibits numerous non-linearities. Most pronounced is an asymmetry in the response to positive and negative SST perturbations. Additionally, we identify a “magnitude-dependence” of the response on the size of the SST perturbation. We then explain how these non-linearities arise as a robust consequence of convective quasi-equilibrium and weak (but non-zero) temperature gradients in the tropical free-troposphere, which we encapsulate in a “circus tent” model of the tropical atmosphere. These results demonstrate that the climate response to SST perturbations is fundamentally non-linear, and highlight potential deficiencies in work which has assumed linearity in the response.

Both the 2023 and 2026 early developing El Niños are having spring crop damage from cold following early record warmth. Newark Area, NJPeriod of record: 1843-05-01 through 2026-04-22DateHighest maximum temperatures (degrees F) Top Record 2nd Record 3rd Record 4/13 92 in 2023 86 in 1977 84 in 2018+ 4/14 93 in 2023 89 in 2026 88 in 2022+ 4/15 91 in 2026 88 in 1960 87 in 1941 4/16 92 in 2002 90 in 2026 89 in 1896

Models correcting stronger with the blocking to start May as this El Niño is developing at a record pace for this time of year. So the growing El Niño combining with other elements will cap the high end warmth potential for a while. We saw something like this back in the spring of 2023 following the April record 90°+ heat with that El Niño which formed early also. New run Old run

In effect that is what happened with the El Niño in 2018-2019 which had La Niña elements preventing it from fully coupling. Perhaps if the RONI and ONI can come into closer alignment it could suppress the Southeast ridge more than we saw back in 2023-2024. But that is really speculative at this point. It looks like we are headed for over +2.0 again on at least ONI and can use this as another test case. None of the seasonal models back in 2023-2024 were able to correctly forecast the stronger ridge building down into the Mid-Atlantic. As they all had the stock El Niño composite.

The 2023-2024 event highlighted the weakness of relying on RONI for that super El Niño when the surrounding tropics were so warm since it amplified the warming even more than the ONI value due to dual warming centers in the Pacific. When the RONI paper came out most of it was focused on the La Nina intensity getting masked by the rising Nino 3.4s while the differential between the WPAC warm pool driving the EWBs suggested the lower RONI than ONI. So the paper never really focused on higher end El Niño events with dual warming centers lowering the RONI. So the new RONI isn’t really a one size fits all solution or an adequate replacement for ONI with higher end El Niño events. https://www.nature.com/articles/s43247-025-02971-1 During the 2023-24 El Niño, the July 2023–June 2024 average global mean surface temperature peaked at 1.58 °C above pre-industrial levels, associated with a record 0.36 °C year-over-year rise. Here we use statistical models and a Green’s Function method to explore the causes for this rise. We show that sea surface temperature accounts for ~92% of the interannual warming, highlighting the critical role of El Niño diversity. Unlike typical El Niños, dual tropical Pacific warming centers in 2023-24 and an eastward-extended North Atlantic jet stream synergistically amplified sea surface temperatures across tropical basins, accelerating the pace of global warming. From an energy balance perspective, ocean heat content accumulated during the preceding La Niña and a continuous increase in absorbed shortwave radiation over the ocean drove sea surface temperature rise. Accelerated warming may push the climate system closer to critical tipping points, emphasizing the need for enhanced monitoring, mitigation, and adaptation strategies.

Yeah, could be related. Same for the El Nino trough in the East which was much weaker in 2015-2016 and 2023-2024. I also think the much warmer adjacent off equator and subtropical oceans could be warping the response also. Those subtropical seas were so much warmer this winter that the weak La Niña ridge in the Southwest was so much stronger than the 1995-1996 weak La Niña response. It’s a bit challenging to give a specific value to just how much each individual marine heatwave is contributing. I have also been noticing discussions already taking place about the new RONI index. I went back and reread the paper on RONI and seems like most of the value was with La Ninas where the off equator warmth was masking the La Niña response. But when it comes to the strongest El Niños they can appear weaker than the past ONI. But as we saw from 2023-2024, the weaker RONI didn’t correspond to a weaker ridge over Canada and the Northern Tier and any less warmth. Plus the global temperature jump was even more impressive than past even stronger ONI higher end El Niños. But we could make an argument that the weaker RONI and warmer off equator to subtropical SST warmth could have weakened the Aleutian trough and the trough in the East under the big ridge. This could also warp the rainfall response in some way than we normally get with such strong El niños related to the Southern Stream response. This is why we should probably still use the traditional ONI for the actual El Niño intensity and incorporate the RONI for the finer details like how the Aleutian Low and other troughs are responding.

Probably related to the big expansion of the +30C warm pool in the Pacific which is several degrees warmer than we would get back in the old days with the strongest El Niños before the oceans warmed so much.

At least for the next few weeks, it looks like the warmer days will be in the 70s rather than the 90s. Plenty of blocking setting up which should cap the higher end temperature potential. These impressive temperature swings seem to have increased in frequency starting around January 2005 with how quickly the record warmth reversed to significantly colder. But the warmest temperatures during the swings most of the time is more impressive than the coldest readings. Climatological Data for NY CITY CENTRAL PARK, NY - January 2005 Click column heading to sort ascending, click again to sort descending. Sum 1160 781 - - 1035 0 4.67 15.3 - Average 37.4 25.2 31.3 -2.4 - - - - 3.5 Normal 39.5 27.9 33.7 - 970 0 3.64 2005-01-01 60 40 50.0 14.8 15 0 0.00 0.0 0 2005-01-02 50 37 43.5 8.5 21 0 0.00 0.0 0 2005-01-03 58 49 53.5 18.7 11 0 0.45 0.0 0 2005-01-04 51 46 48.5 13.8 16 0 0.06 0.0 0 2005-01-05 46 35 40.5 6.0 24 0 0.28 T 0 2005-01-06 41 34 37.5 3.1 27 0 0.62 0.0 0 2005-01-07 42 36 39.0 4.8 26 0 T T 0 2005-01-08 41 35 38.0 3.9 27 0 0.59 T 0 2005-01-09 40 33 36.5 2.6 28 0 0.00 0.0 0 2005-01-10 48 39 43.5 9.7 21 0 0.00 0.0 0 2005-01-11 40 35 37.5 3.8 27 0 0.25 T 0 2005-01-12 39 35 37.0 3.4 28 0 0.12 0.0 0 2005-01-13 59 38 48.5 15.0 16 0 0.00 0.0 0 2005-01-14 66 34 50.0 16.6 15 0 1.03 0.0 0 2005-01-15 34 26 30.0 -3.4 35 0 0.00 0.0 0 2005-01-16 31 27 29.0 -4.3 36 0 0.00 0.0 0 2005-01-17 28 18 23.0 -10.3 42 0 0.03 0.5 T 2005-01-18 18 9 13.5 -19.7 51 0 T T 0 2005-01-19 26 9 17.5 -15.7 47 0 0.03 0.8 0 2005-01-20 30 20 25.0 -8.2 40 0 0.00 0.0 0 2005-01-21 20 9 14.5 -18.6 50 0 0.00 0.0 0 2005-01-22 25 6 15.5 -17.6 49 0 0.93 8.5 0 2005-01-23 26 9 17.5 -15.7 47 0 0.25 5.3 13 2005-01-24 24 8 16.0 -17.2 49 0 T T 14 2005-01-25 33 20 26.5 -6.7 38 0 0.00 0.0 13 2005-01-26 37 17 27.0 -6.2 38 0 0.01 T 13 2005-01-27 18 9 13.5 -19.8 51 0 0.00 0.0 13 2005-01-28 22 5 13.5 -19.9 51 0 0.00 0.0 11 2005-01-29 34 15 24.5 -8.9 40 0 0.00 0.0 11 2005-01-30 38 24 31.0 -2.5 34 0 0.02 0.2 11 2005-01-31 35 24 29.5 -4.1 35 0 0.00 0.0 11

This was a record breaking April temperature drop spanning around 5 days. These charts are just for hourly reports and miss highs or lows recorded between hours. Spots that radiate well dropped more than 60°. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=169&network=NJ_ASOS&zstation=EWR&v=tmpf&hours=111&month=apr&dir=cool&how=exact&syear=1900&_r=t&dpi=100&_fmt=png

FWIW, the April dynamical mean came in at 2.06 for the ONI. This is significantly ahead of 2023 and 2015 at the same point. 2023 was at 1.54 and 2.10 verified. April 2015 was at 1.30 and 2.80 verified. So for the two most recent El Niños reaching an ONI of 2.0 or greater, the spring predictability barrier resulted in too weak a forecast. https://iri.columbia.edu/our-expertise/climate/forecasts/enso/current/ April 2026 Average, Dynamical models 0.764 1.120 1.438 1.709 1.763 1.951 2.060 1.856 1.810 April 2023 Average, Dynamical models 0.460 0.785 1.098 1.328 1.406 1.481 1.547 1.473 1.386 April 2015 Average, dynamical models 0.8 1 1.2 1.3 1.4 1.3 1.3 1.3 1.1

Yeah, would be nice for some improvement of the lower soil moisture to get at least one major storm system while the blocking and STJ is in place.

I try not to get too far ahead of things and just say at this point the temperatures next winter will probably be warmer than last winter was in the Northeast. Just hoping we can keep some semblance of a benchmark track going especially as we approach late January and February. I wouldn’t mind a mild winter at all if we could get a least one nice backloaded style event. The difference between 2015-2016 and 2023-2024 was that we got a great blocking pattern one winter and not so great the other winter. Even 2023-2024 had a good one week period in February with 2 events. But they were narrowly focused into portions of NJ and SNE really couldn’t cash in as much. We did get that record STJ in February associated with the larger event. Obviously, we would want to avoid a 97-98 outcome where we really didn’t get much snow at all. Unfortunately, we just don’t have the technology to forecast snowfall and blocking so many months in advance. Climate Reanalyzer has the 500mb reanalysis maps. But they are delayed a bit to around the 8th of the following month. https://climatereanalyzer.org

As we saw back in 2023-2024, the atmospheric response from the El Nino Ridge parked just north in Canada and the Northern Tier of the CONUS was one of the strongest on record. But the El Niño trough expression through the Aleutian Low and trough across the south to the Mid-Atlantic was much weaker than usual for such a strong Nino ridge which lead to the record warmth with that event. So even the ONI reaching 2.1 really didn’t do that event justice since it failed to incorporate the record Nino 4 +30C warm pool which was the warmest on record. You will notice that the MEI and SOI responses were also much weaker than usual for such a strong event. It will be interesting to see as this one develops whether the SOI, MEI, and RONI lag behind again. All I can say at this early juncture is that the WWB atmospheric component from March and April was much stronger than in 2023 near all time record values leading to the very impressive OKW beneath the surface.

Looks like the STJ really becomes active as we head into May with the rapidly developing El Niño.

We are seeing elements of the spring 2023 pattern with how early and strongly this El Niño is developing. That year had a shift to stronger blocking in late April following early record 90 warmth. Notice the 2 matching dates from 2023 and how close in time the record warmth was. So it’s possible that this week will turn out to be the warmest we see for a while. But rainfall has been generally disappointing. Maybe the developing STJ can allow for some better rainfall opportunities especially by the early summer like we saw in 2023. Newark Area, NJPeriod of record: 1893-05-01 through 2026-04-16DateHighest maximum temperatures (degrees F)Top Record 2nd Record 3rd Record 4/13 92 in 2023 86 in 1977 84 in 2018+ 4/14 93 in 2023 89 in 2026 88 in 2022+ 4/15 91 in 2026 88 in 1960 87 in 1941 4/16 92 in 2002 90 in 2026 89 in 1896

I am curious to see how much rain we actually get vs just low clouds and onshore flow.

Yes, we have had numerous 90°+ events in the Northeast during developing El Niños in April. But the 500mb forecast most closely matches 2023 with a shift to strong blocking. Makes sense since this one is coupling with the atmosphere and is much stronger early on like 2023.

Yeah, the atmosphere seems to be following the April 2023 developing El Niño script. Both April 2023 and 2026 have featured early record 90°+ warmth in the Northeast. Then a reversal to cooler and strong blocking to close out the month.

Yeah, we may get one of our famous spring cut-off low patterns.

The STJ near the Baja is forecast to become more active with the developing El Niño. So it’s looking like more rainfall chances in late April. But the individual storm details will probably have to wait.

Yeah, we have been in an all or nothing snowfall pattern for 30 years now around NYC Metro. Nearly all seasons have been under 18” or over 30” with not many in the mid range. So it’s a bit like a power hitter that strikes out quite a bit between homers. The background warming loads the dice for more strikeouts over time. But the record SST warmth out near the Gulf Stream results in some very long homeruns like we saw back in late February when the STJ activates with good blocking. The ultimate question each season is how many duds will we have to endure before another gem of a season like 2025-2026?

Perhaps the rapid warming which began before the typical El Niño lag in the spring of 2023 is part of a larger change to more frequent strong to very strong El Niños. It’s possible that this is part of a shift in what some researchers have called the PCC. This warming occurred with the early Nino 1.2 rise in SSTs in the early spring of 2023. The cold tongue that was prominent in the EPAC during recent decades has been replaced by much warmer SSTs even during recent La Ninas. This line of research is still very new so it will probably take more observations to develop this theory more fully. But it would be a significant occurrence for the global temperatures and the weather patterns if this new climate state could produce 2.0+ ONI El Niños separated by only 3 years apart. https://www.nature.com/articles/s41467-024-52731-6?utm_campaign=related_content&utm_source=HEALTH&utm_medium=communities The eastern tropical Pacific has defied the global warming trend. There has been a debate about whether this observed trend is forced or natural (i.e., the Interdecadal Pacific Oscillation; IPO) and this study shows that there are two patterns, one that oscillates along with the IPO, and one that is emerging since the mid-1950s, herein called the Pacific Climate Change (PCC) pattern. Here we show these have distinctive and distinguishable atmosphere-ocean signatures. While the IPO features a meridionally broad wedge-shaped SST pattern, the PCC pattern is marked by a narrow equatorial cooling band. These different SST patterns are related to distinct wind-driven ocean dynamical processes. We further show that the recent trends during the satellite era are a combination of IPO and PCC. Our findings set a path to distinguish climate change signals from internal variability through the underlying dynamics of each. Much recent work focused on whether equatorial Pacific cooling over past decades is driven by anthropogenic effects or arises from internally-generated climate variability, like the IPO. A definitive anthropogenic link to the recent trends would allow us to reliably predict a cooler tropical Pacific. As the tropical Pacific is known to be a climatic pacemaker, for (at least) the near-future this would mitigate global warming via ocean heat uptake and low-level cloud feedbacks. Instead, if the cyclic IPO dominates the recent cooling, we may expect a strong warming when it reverses. In support of the first possibility, we have identified an emerging climate change signal in the tropical Pacific across different observational datasets and we call it the PCC. The PCC has distinctive ocean-atmosphere dynamics that differ from those associated with the IPO. We further demonstrate that the recent trends during the satellite era, which have been the focus of significant attention, result from a combination of IPO and PCC. The emerging PCC SST trend pattern features a narrow band of cooling in the eastern equatorial Pacific and warming elsewhere. This SST change is linked to thermocline shoaling/SSH decreases in the central-to-eastern Pacific and dipole-like changes in zonal surface wind stress. In contrast, the recurrent IPO-driven SST trend pattern is characterized by a meridionally broader cooling in the eastern Pacific, zonal dipole-like thermocline/SSH changes and an overall strengthening of tropical Pacific zonal wind stress. We have shown that these distinct ocean circulation changes are a response to different wind stress patterns. These oceanic responses account for surface cooling in the eastern Pacific, with the thermocline shoaling playing a dominant role in the PCC cooling and enhanced zonal advective cooling mainly driving the IPO-related cooling. While basic geophysical fluid dynamics proved sufficient to attribute the observed oceanic changes to surface wind stress, we have not addressed the origins of the wind stress patterns associated with the PCC and the IPO. New research is needed to elucidate the wind changes, but our leading hypothesis is as follows. In response to GHG forcings39,40temperature change in the upper troposphere are stronger than at the surface (Fig. S4), increasing atmospheric static stability. Consequently, the initial SST and surface wind response to rising GHGs might not be amplified as efficiently via Bjerknes feedback as is that for the internal modes on interannual to decadal timescales. Given the differences in thermocline and ocean current patterns associated with the PCC and the IPO, the coupled feedbacks related to ocean dynamics are also expected to differ, potentially contributing to distinct climate pattern formations for decadal variability and climate change. Additionally, climate variations outside of the tropical Pacific may influence the tropical Pacific trade winds26,27,41–44. Further, it has been argued that pronounced decadal-to-multidecadal SST variability in the Atlantic Ocean is also dominated by the response to the same external forcing that the tropical Pacific encounters45. Perhaps the co-occurrence of these long-term trends in different regions is not simply a direct response to rising GHGs but is influenced by inter-basin interactions. More work is needed to disentangle causal relationships among the long-term changes in different basins46,47. Throughout this paper we have taken for granted the widespread assumption that the IPO is an internal mode of the climate system. However, while we worked to distinguish between the recurrent IPO-related decadal variability and the emerging PCC signal, we are open to the possibility that these two may have become coupled together by anthropogenic forcing. They have much in common: shoaling of the thermocline in the east, enhanced upwelling somewhere in the central-to-eastern equatorial Pacific and an enhanced zonal SST gradient across the equatorial Pacific. It seems reasonable to postulate that if the response to radiative forcing is the emerging PCC pattern seen here, then it could initiate coupled ocean-atmosphere feedbacks that favor a negative IPO state that also has an enhanced SST gradient24. This might explain why the most recent IPO swing has been extreme and robust (Fig. S1b). If so, this suggests that in nature forcing is projecting onto natural modes of variability, while it is not clear whether climate models can reproduce this behavior. A new perspective on how internal variability interacts with the climate change signal will be needed in future studies.

Where was this blocking in early March?

If the models are still showing something similar with the June updates, then our first 2.0°+ ONI El Niño events within 3 years would become more likely.