bluewave

December 2015 was unique since it was the first time we had a strong MJO 4-6 with a super El Niño due to the record WPAC warm pool up until that time for such a strong El Niño. So those two forces combining created the historic +13 December which was warmer than many Novembers were around NYC. Luckily, a great blocking pattern emerged leading to the historic snow event around NYC in late January. Plus NYC had their first below 0° reading since 1994 on Valentine’s Day. We had a variation on this much stronger WPAC warm pool theme for the 2023-2024 event. But more spread out winter warmth across the season than one month being some much warmer than the others like in 2015-2016. https://phys.org/news/2021-04-distinctive-mjo-super-el-nino.html#:~:text=Observations show that the western,MJO-related convection was enhanced. When compared to the previous super El Niño events, the warm SST anomaly, or change from average, of the 2015/16 El Niño was located more westward than during the other two extreme seasons. Additionally, no significant cold SST anomaly was detected in the western Pacific. Accordingly, the moisture and air temperature tended to increase in the central-western Pacific during the winter of 2015/16 unlike the previous super El Niño events.

Farmingdale only starts in 1999 so several warmer rankings prior to that would be missing. Islip finished 12th warmest. The strong onshore flow kept LI cooler in the rankings than NYC. Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. 1 2012-04-29 49.8 0 2 2010-04-29 49.0 0 3 2025-04-29 48.6 0 4 2024-04-29 47.9 0 5 1973-04-29 47.5 0 6 2023-04-29 47.3 0 - 2016-04-29 47.3 0 7 1991-04-29 47.1 0 8 2002-04-29 47.0 0 9 2021-04-29 46.4 0 - 1977-04-29 46.4 0 10 1976-04-29 46.3 0 11 1985-04-29 46.1 0 12 2026-04-29 46.0 0 - 2022-04-29 46.0 0 13 2020-04-29 45.8 0 - 1998-04-29 45.8 0 - 1995-04-29 45.8 0 14 2008-04-29 45.7 0 15 1999-04-29 45.6 0

You still haven’t apologized for your fake criticism of my guess that NYC, LGA, and JFK would struggle to reach 50” of snow which I made several years back.

It may be that the SSW in late November set off a chain of events that allowed the Northern Stream to weaken enough by late February for the KU BM event. This almost reminds me of a dance between the Northern Stream and Southern Stream. When the NS becomes too overpowering, it’s like it keeps stepping on the feet of the STJ dance partner suppressing it too much. When the Northern Stream backs off just enough and allows the STJ to lead, then it opens the door for great Benchmark KU events like in late February.

You probably won’t find much literature related to the Northern Stream intensity across the NP following SSWs since it’s a bit of a niche topic. Plus this stronger Northern Stream only emerged since 2018-2019 and might be to short of an interval to gain much interest for research.

Yeah, late November SSW didn’t translate into weaker Northern Stream until late January and especially February. This allowed the STJ to lead more allowing the KU BM event in late February. But the effect quickly wore off in March and we reverted to the 2020s mean of warm and snowless Marches with a dominant Northern Stream. Plus the NAO has been swinging more from one extreme to the other over time. So we weren’t able to get the extended November to May -NAO of 1995-1996. Several overlapping warming influences working against a 1995-1996 repeat. Especially the overpowering ridge in the Southwest resulting in the 2nd warmest winter for the CONUS.

I am happy that we got one of the earliest SSWs on record back in late November. It was a big reason that this was the first winter with below average temperatures and above average snowfall in 11 years around NYC Metro. It’s possible that if the SSW had occurred later in the season, then with the lag could have resulted in the benchmark track coming too late in March when temperatures would have been more marginal for heavy snows along the coast. As it was the SSW occurred in late November with a 2-3 month lagged response for the BM KU track to materialize. December snows were all Northern Stream clippers.

This was the 8th warmest March 1st to April 29th for NYC at 50.8°. Time Series Summary for NY CITY CENTRAL PARK, NY Warmest March 1 April 29 Click column heading to sort ascending, click again to sort descending. 1 1945-04-29 53.2 0 2 2012-04-29 52.8 0 3 2010-04-29 52.7 0 4 1921-04-29 52.1 0 5 2024-04-29 51.7 0 6 2016-04-29 51.0 0 7 2023-04-29 50.9 0 8 2026-04-29 50.8 0 9 2025-04-29 50.7 0 10 1985-04-29 50.2 0 11 1946-04-29 50.1 0 12 2021-04-29 50.0 0 - 2002-04-29 50.0 0 - 1977-04-29 50.0 0 13 1991-04-29 49.9 0 - 1903-04-29 49.9 0 14 1973-04-29 49.7 0 15 1979-04-29 49.5 0 16 1998-04-29 49.4 0 - 1986-04-29 49.4 0 - 1976-04-29 49.4 0 17 1910-04-29 49.2 0 18 2020-04-29 49.1 0 - 2006-04-29 49.1 0 - 1990-04-29 49.1 0 - 1987-04-29 49.1 0 19 1968-04-29 49.0 0 20 2000-04-29 48.9 0 - 1981-04-29 48.9 0 21 2022-04-29 48.8 0 22 2008-04-29 48.7 0 - 1938-04-29 48.7 0 - 1878-04-29 48.7 0 23 1963-04-29 48.5 0 24 2019-04-29 48.4 0 - 1913-04-29 48.4 0 25 2009-04-29 48.3 0 - 1995-04-29 48.3 0

This past winter was really interesting in that we got the warm pool east of Japan interacting with the warm pool off of California and the Baja. So it prevented us from getting a strong +PDO like we had in 1995-1996 with that weak La Niña. So while this was the best winter of the 2020s so far from NYC to Boston, the overpowering Northern Stream was only able to relax from late January to late February. This prevented the wall to wall historic snowy outcome from November 1995 to April 1996. Notice how much stronger the Northern Stream was this past winter compared to 1995-1996. My guess is that the warm pool east of Japan in concert with the much warmer climate may have increased the Northern Stream just enough to take the 1995-1996 historic snows off the table. But we still were able to get the outstanding February KU before the Northern Stream returned for March.

Yeah, I get the joking. It’s good to keep things light in here. We switched out of the traditional -PDO +PDO relationship following the big warming east of Japan after the 2015-2016 El Niño.This really increased following 2018-2019. So the current models are forecasting more of basin-wide warming where we get a zone of warm SSTs from Japan to the Baja. We saw that this past winter going into the spring with the record +PMM and remaining warm pool east of Japan. We will probably have to revisit this paper again after this event and see where things stand. https://www.nature.com/articles/s41558-025-02482-z Pan-basin warming now overshadows robust Pacific Decadal Oscillation The Pacific Decadal Oscillation (PDO) has served as a key index linking basin-scale climate variability to marine ecosystem changes in the North Pacific. However, recent apparent breakdowns of PDO–ecosystem correlations have raised concerns about the stability of the mode and its continued relevance in a warming climate. Here we show that basin-wide warming now overwhelms PDO-related sea surface temperature (SST) variability, although neither the PDO’s spatial pattern nor its strength have changed. We introduce the pan-basin pattern as a complementary index to describe the non-stationary SST baseline of the North Pacific. Regional SSTs increasingly reflect the superposition of these two signals, providing an explanation for weakened or inverted PDO–ecosystem correlations. Future use of the PDO index in management will require discerning the effects of internal dynamics from those of absolute changes in SST as extreme and no-analogue ocean conditions driven by interacting natural variability and anthropogenic warming become more common. We demonstrate that the leading mode of interdecadal North Pacific SST changes recently transitioned from the PDO to a pattern of unidirectional change across the entire basin (that is, the PBP). For the first prolonged period of the recent observational record, a negative ‘cold’ PDO phase failed to coincide with cool SST anomalies in the eastern Pacific—a harbinger of the increasing non-stationarity in relationships between the PDO and regional SSTs (Fig. 3d,e). Despite explaining proportionally less variance, ongoing robust PDO variability indicates that drivers of the mode’s SST anomaly footprint have been resilient to warming through the early twenty-first century (Figs. 1 and 2). As the PDO is a statistically emergent pattern integrating several processes (for example, stochastic Aleutian Low forcing, teleconnections with the tropics, and ocean Rossby waves)4,47, its future evolution will depend on how these contributing processes are cumulatively impacted by warming across timescales. Although the historical physical drivers of North Pacific decadal variability are relatively well understood4,48, the biophysical mechanisms through which ecosystems respond are less so. The PDO has historically served as a reliable proxy for SST in much of the North Pacific. However, as regional SST anomalies continue to diverge from those historically expected based on PDO signals (Fig. 3d–g), there will be a growing need to distinguish impacts associated solely with SST anomalies from those produced by the dynamics related to the PDO (for example, changes in upwelling, transport or source waters). For example, since the 2021 transition into the negative PDO phase (Figs. 3d,e and 4b,c), warming is superimposed on a cold PDO regime in the eastern North Pacific, leading to confusion in the community regarding the expected biological effects26. Further investigation into the mechanisms behind PDO–ecosystem relationships should prioritize discernment of temperature-specific effects on biology from the effects of other physical or biogeochemical processes. Given the ongoing stability of the PDO pattern, the PDO index probably remains a useful indicator of North Pacific climate variability, but perhaps with its ecological relevance in how it reflects changing dynamical processes rather than regional SST anomalies. As the PBP–temperature baseline climbs in concert with global ocean warming, local and regional SST anomalies that would historically have been associated with an exceptionally strong PDO and/or El Niño (for example, >2 standard deviations) will occur more frequently. For example, constructive signals between internal variability and secular warming from 2014–2020 contributed to warm temperature extremes during this period (for example, ref. 49). Quantification of the range of internal variability related to the PDO and other modes will be needed to constrain the potential for climate extremes resulting from interaction of internal variability and anthropogenic warming, leveraging approaches such as palaeoclimate records, long model simulations or large model ensembles50,51. Constraining internal variability and stability is also necessary for understanding the future of PDO impacts beyond the North Pacific (for example, theorized impacts on hydroclimate in western North America and northeastern Asia)52,53,54,55,56,57 and its role in modulating global climate. Global-scale trends and internal variability are now both important determinants of North Pacific climate48,58, with the influence of pan-basin warming surpassing that of the PDO within the past decade. The combination of long-term warming and natural variability has already begun to produce profound physical and ecological changes throughout the North Pacific, including severe marine heatwaves with ecosystem-wide impacts59,60, rapid sea ice declines and novel weather patterns in the Alaskan Arctic61, and new human–wildlife conflicts62. Management decisions based on historical baselines will fail to capture increasingly important emergent interactions between anthropogenic warming and internal variability. This increased uncertainty in associations between basin-scale variability and regional responses underscores the need for management approaches to incorporate dynamical modelling and prediction of North Pacific climate (for example, ref. 63), rather than relying on historical relationships with basin-scale indicators as predictors. Given that the internal variability of the North Pacific is especially strong, a similar emergence of pan-basin warming over internal variability is probably already occurring in other basins, suggesting that the recontextualization of indices of climate variability under warming is needed widely.

It will be interesting to see how things play out. But the long range models continue the warm pool east of Japan. We may have to wait until we get closer to the peak of this event to know for sure.

Nino 3.4 responding to the kelvin wave as it’s now the 3rd warmest for the date since the early 80s.

It has been mostly a brown lawn issue here since late 2024. But we did have our local reservoirs running low at times. Thankfully nothing as extreme as the water restrictions areawide back in 2002. The biggest issue for agriculture this spring has been the record temperature swing. While spring record warmth is arriving earlier these days, the last freeze date has held more steady. This has resulted in the big local crop losses.

It will be interesting to see if the coming El Niño can shift us out of this dry pattern which began in September 2024.

2009 was the last average temperature summer in Philly against the 1951-2000 mean. This was the first slightly cooler winter in Philly since 2015-2016. So it’s pretty representative of the wider trends across the region and nation.