bluewave

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 The cold tongue that was prominent in the EPAC during recent decades has been replaced by much warmer SSTs even during recent La Ninas.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.

The Nino regions have been steadily warming over the years. So it takes a lower ONI departure in a modern climate to record the same actual SSTs. The atmospheric forcing responds to the actual SSTs especially when getting close to the threshold temperatures. This is why we had such a strong El Niño response with regard to the 500mb and ridge over Canada and the Northern States with record warmth back in 2023-2024 with a lower ONI than 1997-1998. The totality of the SST warmth from Nino 1+2 to Nino 4 extending west of the Dateline was among the highest ever recorded for the actual SSTs during an El Niño. ONI and RONI values for just 3.4 won’t always reflect this. The lower RONI values may have been a result the lack of a significant El Niño trough in the East and South and weaker Aleutian low than normal. So we didn’t need ONI or RONI values as strong as 1997-1998 or 2015-2016 to create similar effects. So if this event can max out at around 2.0° ONI or higher in Nino 3.4, then it possible it can have an effect closer to 2.3° to +2.5° in the old days especially with the Nino ridge and warmth to the north. The actual SSTs may be more important than the specific departures in measuring the actual magnitude necessary to initiate a strong El Niño atmospheric response. Nino 3.4 got to 28.57° during the early winter back in 2023. https://www.cpc.ncep.noaa.gov/data/indices/oni.ascii.txt NDJ 2023 28.57 2.06 Notice how much mare expansive the +30C warm pool was in the Central Pacific in December 2023 than 1998 which lead to the record global temperature jump and warmth that winter. ONI and RONI values won’t always capture this.

Long range models are moving toward more blocking during the last week of April. This was what happened following the mid-April record warmth back in 2023 during the developing El Nino. So it will be interesting to see if the models like the EPS continue with the blocking as we get closer in time since these week 2 forecasts aren’t always the most reliable.

Developing El Niños in April have pretty reliably resulted in near to record highs over 90° around the area like we most recently experienced in mid-April 2023. Newark Area, NJPeriod of record: 1931-01-01 through 2026-04-11 Developing El Niños bolded Highest maximum temperatures (degrees F)Top Record 2nd Record 3rd Record 4/1 82 in 1978 81 in 2026 80 in 2016 4/2 83 in 1967 80 in 1963 78 in 1946 4/3 81 in 1967 80 in 1981 77 in 2002 4/4 82 in 1950 79 in 1974 78 in 2010 4/5 83 in 1985 81 in 2010 75 in 1974 4/6 83 in 2023 80 in 1947 77 in 2010+ 4/7 92 in 2010 85 in 1991 84 in 1942 4/8 88 in 1991 84 in 2010 84 in 1959 4/9 85 in 2013 84 in 1991 78 in 1970 4/10 82 in 2017 82 in 1955 77 in 2008 4/11 87 in 2011 84 in 2017 84 in 1955 4/12 90 in 1977 87 in 2023 82 in 1996 4/13 92 in 2023 86 in 1977 84 in 2018+ 4/14 93 in 2023 88 in 2022 88 in 1941 4/15 88 in 1960 87 in 1941 85 in 1949 4/16 92 in 2002 88 in 2012 88 in 2003 4/17 97 in 2002 88 in 1976 83 in 1941 4/18 93 in 2002 93 in 1976 85 in 1964 4/19 92 in 1976 91 in 2002 89 in 1985 4/20 91 in 1941 88 in 2005 85 in 1938 4/21 88 in 1957 84 in 1985 84 in 1936 4/22 87 in 1985 86 in 2001 86 in 1973+ 4/23 88 in 1996 86 in 2007 82 in 1990+ 4/24 87 in 2001 84 in 2011 83 in 1994 4/25 91 in 1960 90 in 2009 87 in 1939 4/26 93 in 2009 85 in 2011 83 in 1985 4/27 94 in 1990 92 in 1994 90 in 1962 4/28 90 in 2009 90 in 1990 89 in 2021+ 4/29 91 in 1974 86 in 2024 86 in 2017+ 4/30 91 in 1942 87 in 1985 85 in 1941

Great write up from ECMWF on how to interpret the recent El Nino forecast so early in the development process. https://www.ecmwf.int/en/about/media-centre/science-blog/2026/el-nino-2026

Looks like the usual NJ warm spots can see their first 90° readings of the season this week.