bluewave

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.

Similar to the Euro which is what you would expect if these record WWBs continue past the spring forecast barrier.

There was very heavy rain and flooding early that July before the warmer conditions arrived as the El Niño first began to take hold. The late spring that year was defined by the record warmth in Canada and drought leading to all the wildfires and the record poor air quality conditions in NYC in early summer. That being said, each year is different which variation from previous El Niños. While it was a cooler summer relative to the 2020s, it was still warmer than most summers in the earlier decades. The progress of “cooler” summers since the 1990s

The summer of 2023 wasn’t really that cool at all. But relative to the other recent years it seemed that way. I guess the new definition of a cool summer in the 2020s is under 30 days reaching 90° at a warm spot like Newark as was the case in 2023. An actual cool summer like 2014 and 2009 had 15 or fewer days. A really cool summer like 1996 had under 10 days. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec Days Reaching 90° Click column heading to sort ascending, click again to sort descending. 2025 39 0 2024 33 0 2023 29 0 2022 49 0 2021 41 0 2020 31 0 Coolest summers since 1961 Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec Days Reaching 90° Click column heading to sort ascending, click again to sort descending. 1 1967 7 0 2 1996 9 0 3 1985 11 0 4 1982 12 0 - 1975 12 0 5 2004 13 0 6 2009 14 0 - 1962 14 0 7 2014 15 0 - 1976 15 0 - 1969 15 0 The thing to watch as we head into the summer is if a much wetter pattern than we have been experiencing can develop. Since we had some record rainfall and flooding events going into the summer in 2023. Hard to tell at this early stage if this El Niño will respond with that much wetness. Long range precipitation forecasting is very low skill.