bluewave

Wonder if it will be possible to get some 90° heat and dry conditions around Memorial Day for a change? The last time there was 90° heat was back in 2022 but there was some rain on Saturday. All the other 2020s holiday weekends featured cooler to near average temperatures or rain on at least one of the days. Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2025-05-24 69 50 -6.0 0.02 2025-05-25 71 50 -5.3 T 2025-05-26 75 54 -1.6 0.00 Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2024-05-25 81 63 6.2 T 2024-05-26 84 66 8.9 T 2024-05-27 78 66 5.6 0.33 Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2023-05-27 80 54 0.6 0.00 2023-05-28 80 56 1.3 0.00 2023-05-29 79 59 2.0 0.00 Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2022-05-28 79 66 5.8 0.24 2022-05-29 80 62 4.0 0.00 2022-05-30 91 62 9.2 0.00 Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2021-05-29 52 49 -16.5 0.58 2021-05-30 53 48 -16.8 1.15 2021-05-31 76 51 -4.2 T Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2020-05-23 71 55 -2.2 0.79 2020-05-24 68 53 -5.0 T 2020-05-25 73 56 -1.3 T

The tropical forcing tends to focus in areas where the absolute SSTs approach +30C regardless of the departures getting smaller due to climate change. This is one of the reasons that the forcing was so much further west in 2023-2024 and 2015-2016 than in 1997-1998. But it’s possible that if the RONI remains lower relative to the ONI again like in 2023-2024, we may not get the stronger Aleutian Low development like in earlier El Niños. Same for the trough that usually sets up over the Mid-Atlantic and Southeast which was missing back in 2023-2024. Still too early to tell if the troughs will be weaker again like in 2023-2024 allowing more Southeast ridge development than usual. It may be that if the El Niño gets stronger than 2023-2024 in both ONI and RONI, we get more of a traditional stronger Aleutian Low and low in the Southeast. Plus the warm pool east Japan could influence the jet development leading to weaker troughs also even if the SSTs are outside the 20N to 20S RONI range. Then we have the expansion of the subtropical ridges which could also come into play. Remember, we had a weak La Niña in 2025-2026 and the strongest subtropical ridge near the SW U.S. ever from November to March. So these ridges are becoming more dominant than the troughs.

My guess is that the ultimate peak we see in the fall will probably be influenced by how much WWB follow up we get. The recent models back off a bit for early May. They now forecast the next larger one by mid to late May. Could make the difference between a peak in the 2.0 to 2.4 range vs 2.5+. New run Old run

The all-time Nino 3.4 C record was 29.8C set in November 2015. It will be interesting to see the new Euro forecast in a few days. As the middle of its ensemble mean forecast was fairly close with the 2015-2016 event. https://www.cpc.ncep.noaa.gov/data/indices/ 18NOV2015 23.8 2.0 28.0 2.9 29.8 3.0 30.3 1.7 https://www.ecmwf.int/en/newsletter/151/meteorology/2015-2016-el-nino-and-beyond The 2015/16 El Niño broke warming records in the central Pacific, represented by the NINO3.4 and NINO4 indices. At its peak in November 2015, the NINO3.4 SST anomaly reached 3.0°C, breaking the previous record of 2.8°C set in January 1983. In the NINO4 region, large positive anomalies are hard to achieve because average conditions are already warm. In 2015, the anomaly reached 1.7°C, a substantial increase of 0.4°C on the previous record, set in 2009. SST analyses become less precise going back in time, but the size of the anomalies in NINO4 and NINO3.4 means we are fairly confident that these are record values for the whole of the observational period back to 1860. By contrast, in the eastern Pacific (monitored by indices for the NINO3 and NINO1+2 regions) the El Niño remained below the level of the 1982/83 and 1997/98 events. It must be borne in mind that the anomaly records depend on the reference climate, which in this case is a 30-year climate (1981–2010).

Pretty impressive for Nino 3.4 SSTs to be approaching 29C in early May. This is near the record for so early in the El Niño development. The 30C warm pool is fairly expansive near the Dateline.

Models backing off on the cooler temps they were recently showing to start May. We should make it into the 80s this week on the warmest day. The cooler days should be closer to 60° at the warm spots with 50s in other locations which is an improvement over cooler days earlier in the spring. Looks like the coldest departures will settle in over the Great Lakes with a little warmer near the coast.

It’s interesting that the CFS is also showing a -WPO at least in December.

This was one of our most -WPO winters in years. Maybe it’s related to the warm pool east of Japan extending all the way across to California. When the warm pool was there and we had a cold pool near California it lead to the 22-23 winter and the strong +WPO.

Even though the Cansips now gets to +2.0 on the ONI, the RONI looks weaker. So the big warm pool east of Japan seems to be resulting in a record -WPO for such a strong El Nino. Notice how the Aleutian low is substantially weakened and is further south just off of California. I agree with you that we typically haven’t seen cool anomalies near the Great Lakes with such strong events in the past. Perhaps the warm pool east of Japan could lead to a weaker Aleutian low and a more neutral WPO that we typically see with such strong El Niños. We know these long range model forecasts are often full of errors. If they can just get one thing right like the WPO, then I would consider it a valuable contribution. But it’s still to early to know for sure about details like the WPO this far out in time. I guess the one takeaway is that most of the models are now at or above +2.0 for at least ONI.

NYC was very close to JFK and LGA in staying under 50”. So even if there was a small undermeasurement, it would have been closer to 45” and not 50”. For NYC along with JFK and LGA they need a winter average temperature near 32.0° or lower just to have a chance at a 50” season. While it’s necessary, it’s not always sufficient. That’s what happened this season. ISP was able to have a 50”+season in 2017-2018 without NYC, JFK, and LGA averaging near freezing. Same for EWR coming closer to 50” in 2020-2021 than other local stations during another milder than average winter. ISP and EWR tend to get heavier snowfall totals than NYC, JFK and LGA, due to the best banding often setting up just west of the Hudson and out across Long Island. It’s on rare occasions like January 2016 and February 2006 that the jackpot band sets up directly over or near NYC, JFK, and LGA. So this was the first winter in 11 years that NYC averaged near 32° as the winters have warmed so much after the 2015-2016 global temperature baseline jump. It’s uncertain when the next one will occur. Since the challenge for NYC to reach 50” arises from a shrinking pool of winters near 32° as the climate warms. But I think that there could be a small chance that it could happen. NY LAGUARDIA AIRPORT WBAN 45.6 CT GUILFORD CENTER 2.7 WSW CoCoRaHS 45.5 NY JFK INTERNATIONAL AIRPORT WBAN 45.4 NY AMITYVILLE 0.6 NNE CoCoRaHS 45.4 NY BELLMORE 0.9 SSE CoCoRaHS 45.1 NJ WEST MILFORD TWP 2.5 SSE CoCoRaHS 45.0 NJ PALISADES PARK 0.2 WNW CoCoRaHS 44.9 NJ NEW PROVIDENCE 0.8 ESE CoCoRaHS 44.8 CT MYSTIC 0.9 W CoCoRaHS 43.9 NY NY CITY CENTRAL PARK WBAN 43.4 NY CORNWALL ON HUDSON 0.6 NNW CoCoRaHS 43.1 NY LINDENHURST 1.0 NE CoCoRaHS 43.1

December 2015 was unique since it was the first time we had a strong MJO 5 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 continuation of 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. No great blocking pattern in 2023-2024 so the seasonal snowfall was a disappointment for many. With the strongest MJO 4-7 activity in January and February. This was the 2nd time that such a strong El Niño had robust MJO activity in this region due to how far west the record +30 C warm pool extended in the Pacific. https://phys.org/news/2021-04-distinctive-mjo-super-el-nino.html#:~:text=Observations show that the western,MJO-related convection was enhanced. Observations show that the western Pacific MJO activity was strongly suppressed during the peak phase of the 1982/83 and 1997/98 super El Niño events. However, during the crest of the 2015/16 super El Niño event, western Pacific 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.