bluewave

Yeah, looks like a continuation from last winter. Probably related to localized warm pool and forcing south of Hawaii. The strong -PDO -PNA couplet was classic Maritime Continent Niña forcing. So a bit of a hybrid pattern.

Only the 5th time at Newark with an April max Temperature higher than May. Monthly Highest Max Temperature for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Year Apr May Season 2002 97 90 97 1990 94 83 94 2023 93 90 93 2009 93 87 93 1976 93 83 93

Based on these cooler May temperatures across the Arctic, the melt pond season is probably getting off to a slower start. This is what the melt pond model uses to project a September minimum when the data is released in June by Will Gregory CPOM. So this could mean that the 2012 record will be safe for another year. It’s the opposite of the May record warmth which lead to the big melt year in 2020. https://ocean.dmi.dk/arctic/meant80n.uk.php

And the Australian wildfires also.

Those +6C anomalies below the surface have been there since March and the best Nino 1+2 was able to do before backing off to +1.7 was +2.7. A true east based like 97-98 pushed close to +4 with +10C anomalies below the surface. That year had record WWBs from March onward which has been lacking this year. There haven’t been any big EPAC WWBs after March. So 1+2 couldn’t push to +4 like in 97-98 with the record WWBs. While this has started out east based, there haven’t been any signals yet of becoming a big east based event yet like 97-98. Especially with the record WPAC warm pool this year instead of the cold pool which was in place in 97-98.

Trade winds have always been a red herring. The important effect is in the thermocline, where the tidal forces rule. 9:14 AM · May 17, 2023 Necessary but not sufficient without the trades relaxing also. https://www.climate.gov/news-features/blogs/why-making-el-niño-forecasts-spring-especially-anxiety-inducing The heat in the subsurface tropical Pacific Ocean is a necessary precursor for El Niño but it is not always sufficient. Let’s focus on #1 first: the persistence of the surface winds. Dr. Capotondi has published research exploring the relationship of surface winds across the tropical Pacific with ENSO. She used a very detailed satellite-based wind dataset for her analysis and found that the interannual changes in the surface winds are the key ingredient for triggering El Niño (footnote #2). Without persistence of these tropical winds, many El Niño events struggle to achieve lift off and can fizzle. It is this interannual wind variability that determines whether you get a major El Niño (e.g. 1997-98) or an El Niño “bust” (e.g. 2014). Let’s examine the figures below to visualize this. Starting in March 1997, westerly wind anomalies (warm colors) began to form over the western tropical Pacific Ocean (left panel). In the 1997 case, the interannual variability in the winds (middle panel) was especially strong and long lasting, extending over a year and shifting very gradually eastward with time. A major El Niño event formed and peaked during the 1997-98 winter. Now let’s look at the same period of months during 2014, which, in the spring, was predicted to be a potentially major El Niño event. Right on cue, similar to 1997, the westerly wind anomalies began early in the calendar year and lasted through April (left panel below). However, for some unknown reason, the westerly winds began dissipating and the interannual wind variability was very weak-to-nonexistent for the rest of 2014 (middle panel below).

It’s why the models have been struggling so much with their El Niño forecasts since 2012. Record warmth in the WPAC drives stronger trade winds closer to the Dateline. So the models underestimate this influence longer range leading to too much El Niño warming in 3.4. The only model success was 15-16.

There are several papers on the expansion of the WPAC and NW Atlantic warm pools which have lead to the model biases that you mentioned. MJO stalling out longer in phases 4-6. Plus the long range under modeling of the SE Ridge or WAR.

@jconsor showed how the models beyond 10 have been underestimating the strength of the trades east of the Dateline. So the El Niño forecasts from various models won’t be very reliable longer range if this bias continues. Nino 3.4 will continue to lag 1.2 and the WPAC warm pool. The April monthly forecasts for May also overestimated the Nino 1+2 forcing and under estimated the WPAC warm pool forcing. April Forecast for May vs verification so far http://seasonal.meteo.fr/content/PS-previ-cartes?language=en

Trades still pretty strong east of Dateline so Nino 3.4 cooled a little bit in recent days.

The winter extremes since the 09-10 have been off the charts. Numerous individual season firsts including changes from year to year. So not an easy period for long range winter forecasts. Record SE Ridge or WAR patterns since December 2015 leading to first run of 8 warmer than average winters in Northeast. 09-10….Strongest -NAO -AO winter and all-time seasonal snowfall totals in Midatlantic. One of the strongest purely Modoki El Niño’s on record. 10-11 strongest -AO -NAO for such a strong La Niña and record 33 day snowfall totals around NYC metro. 11-12 very impressive +EPO and winter warmth leading to summer in March pattern. 12-13……Record snowfall rates and totals with Nemo. 13-14……Record NE PAC blocking and warm blob leading to cold and snowy in the East. 14-15 record NE PAC blocking continues combined with record +NAO and record Boston snowfall. Trades staying up result in weak Modoki signature. Several models forecast very strong El Niño early on. 15-16 furthest west based super El Niño. First MJO 4-6 so strong in December super El Niño leading to +13 December. All-time heaviest snowstorm in NYC during January. First below 0° in February since Jan 94. 16-17 unusually snowy on parts of Long Island for such a warm and weak La Niña. 60° warmth a day before blizzard in February. Have seen this warm to snowy or snowy to warm repeating more frequently. 17-18 great post Christmas to early January winter pattern with the record 950mb benchmark blizzard. Record La Niña shift to warm in February with first winter 80° around NYC in February. Highest 500 mb height on record for cold season in February in Northeast. Record 30” snows on Long Island in March. 18-19 very rare uncoupled El Niño due to record WPAC warm pool. 19-20 near record warmth and +NAO with 2nd strongest IOD 20-21 back to La Niña with unusually strong December +PNA for a -PDO. Also one of our more recent south based -AO blocks makes appearance in December with snowy outcome. Great finish to season in February especially for a La Niña which is usually more front-loaded. 21-22….Strongest January +PNA blocking following such a record October -PDO dipping below -3. 22-23….First December -AO so south based which was the 2nd overall most negative for month. Lowest December snowfall outcome for such strong -AO. Warmest rest of winter following such strong December blocking.

Yeah, we were getting clues in the fall of 18 that the El Niño wasn’t coupling. Then record IOD in the fall of 19 seems to have drove the record polar vortex and +NAO that winter. So the WPAC warm pool won out in 18-19 and the Indian Ocean in 19-20. https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.1005 Predictability of European winter 2019/20: Indian Ocean dipole impacts on the NAO Steven C. Hardiman, Nick J. Dunstone, Adam A. Scaife, Doug M. Smith, Jeff R. Knight, Paul Davies, Martin Claus, Richard J. Greatbatch First published: 30 July 2020 https://doi.org/10.1002/asl.1005 Citations: 26 Funding information: Met Office Hadley Centre Climate Programme funded by BEIS and Defra SECTIONS PDF TOOLS SHARE Abstract Northern Europe and the UK experienced an exceptionally warm and wet winter in 2019/20, driven by an anomalously positive North Atlantic Oscillation (NAO). This positive NAO was well forecast by several seasonal forecast systems, suggesting that this winter the NAO was highly predictable at seasonal lead times. A very strong positive Indian Ocean dipole (IOD) event was also observed at the start of winter. Here we use composite analysis and model experiments, to show that the IOD was a key driver of the observed positive NAO. Using model experiments that perturb the Indian Ocean initial conditions, two teleconnection pathways of the IOD to the north Atlantic emerge: a tropospheric teleconnection pathway via a Rossby wave train travelling from the Indian Ocean over the Pacific and Atlantic, and a stratospheric teleconnection pathway via the Aleutian region and the stratospheric polar vortex. These pathways are similar to those for the El Niño Southern Oscillation link to the north Atlantic which are already well documented. The anomalies in the north Atlantic jet stream location and strength, and the associated precipitation anomalies over the UK and northern Europe, as simulated by the model IOD experiments, show remarkable agreement with those forecast and observed. In winter 2019/20, the observed sea surface temperatures in the west/east parts of the Indian Ocean basin were anomalously warm/cold, leading to a positive Indian Ocean Dipole (IOD; Saji et al., 1999; Webster et al., 1999) that was the second strongest recorded since 1972 (Doi et al., 2020). A knowledge of the teleconnection pathways between the IOD and the North Atlantic gives greater confidence in the seasonal forecast skill they offer. The frequency of positive IOD events has doubled in the 20th century, and their intensity has also increased, with this trend projected to continue (Abram et al., 2020). It is likely, therefore, that such connections will become increasingly important for seasonal forecasting of European winters during the rest of the 21st century.

Some spots could approach record lows tonight.

ENSO has been competing with marine heatwaves in other regions. So the combination of multiple forcing areas yields new patterns. This is especially true with the El Niños due to the record WPAC warm pool imparting more of a MJO 4-6 La Niña influence. Just look at all the incorrect El Niño seasonal forecasts since 12-13. Several La Ninas over this period have featured Nino-like precipitation totals in California in years like 16-17 and 22-23. So we need to take a more comprehensive approach to seasonal forecasting. Pre-2010 analogs haven’t been working out in this newer climate era.

Yeah, the stronger years were colder near SA but still pretty cold back to Nino 4. Snowier composite NYC Less snowy

La Ninas seem to have been working differently since 10-11. Our strongest La Ninas years in multiyear events have been snowier around NYC. The weaker ones had less snow. Lowest fall into winter trimonthly ONI and NYC snowfall https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php 22-23….-1.0…2.3” 21-22…..-1.0…17.9” 20-21….-1.3…38.6”….strongest of 3 year event 17-18…..-1.0…..40.9”…strongest of 2 year event 16-17……-0.7….30.2” 11-12…..-1.1…..7.4” 10-11……-1.6…60.4”….strongest of 2 year event

Generally need much stronger WWBs getting east of dateline plus subsurface warmth near or over +2 to go super. We haven’t seen either yet. Really no way of knowing what the peak in 3.4 will be based off of May and June Nino 3.4 to 1.2 surface temperatures. The ENSO models will just continue the momentum forward of what the SSTs are initialized at. That only works out in years like 15-16 with high upper ocean heat at strong WWBs. The models showed excessive momentum in years like 2014 when the trades stayed up. If the trades can relax in next few months, then we could see a Nino 3.4 peak of +1.4 to +1.9. But if the trades stay up, then we would probably only peak +0.8 to +1.3 and run the risk of not coupling enough due to WPAC warm pool like got in 18-19. Then we would be looking at another Nina-like winter next year. The WPAC warm pool remains the wild card.

But the subsurface has leveled off around 1c instead of 2c at this time in 1997. So 1-2 had a peak a few weeks ago before leveling off. Now 3.4 has made it to around .5c. Main question is how much warmer 3.4 can get just based on 1.2 spreading out instead of strong WWBs and a warmer subsurface. Will be interesting how much warmer 3.4 needs to be for the trades to weaken since the WPAC warm pool is still so strong. Probably will need the trades to relax to make it to 1.5 strong. Was around 2C at this point in 1997 leading in steady rise to super El Niño over 2C in 3.4 So still no indication that we can have a super event this time around since WWBs and subsurface lagging those years. Models not good at forecasting Nino 3.4 peaks until the summer. https://www.climate.gov/news-features/blogs/enso So, what’s the big deal in the spring? Especially when it comes to predictions of El Niño? It comes down to uncertainty in two of the main ingredients that give rise to El Niño. In the spring, it is difficult to know whether surface west-to-east (“westerly”) wind anomalies across the tropical Pacific Ocean will continue through the summer and persist long enough to reinforce the developing El Niño. The heat in the subsurface tropical Pacific Ocean is a necessary precursor for El Niño but it is not always sufficient. Let’s focus on #1 first: the persistence of the surface winds. Dr. Capotondi has published research exploring the relationship of surface winds across the tropical Pacific with ENSO. She used a very detailed satellite-based wind datasetfor her analysis and found that the interannualchanges in the surface winds are the key ingredient for triggering El Niño (footnote #2). Without persistence of these tropical winds, many El Niño events struggle to achieve lift off and can fizzle. It is this interannual wind variability that determines whether you get a major El Niño (e.g. 1997-98) or an El Niño “bust”(e.g. 2014).

Need the southern stream low to keep moving on the Euro for heavier rains instead of getting suppressed like the CMC.

Top 10 coldest for late May. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Rank Ending Date Lowest Min Temperature May 25 to May 31 Missing Count 1 1949-05-31 39 0 2 1936-05-31 40 0 3 1961-05-31 42 0 - 1956-05-31 42 0 4 1967-05-31 43 0 - 1935-05-31 43 0 5 1938-05-31 44 0 6 1992-05-31 45 0 - 1963-05-31 45 0 - 1945-05-31 45 0 - 1940-05-31 45 0 7 2013-05-31 46 0 - 1947-05-31 46 0 - 1946-05-31 46 0

That was 2013.

Could be our first year with an April max higher than May since 2009. Monthly Highest Max Temperature for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Year Apr May Season 2023 93 90 93 2022 88 98 98 2021 89 96 96 2020 69 86 86 2019 80 90 90 2018 84 94 94 2017 87 94 94 2016 83 96 96 2015 82 91 91 2014 83 88 88 2013 85 94 94 2012 88 92 92 2011 87 92 92 2010 92 95 95 2009 93 87 93

The WPAC warm pool is still doing most of the forcing this month. There continues to be an extension to south of Hawaii like we saw last winter. That’s what gave California the localized more Nino-like record precipitation. Need the WPAC warm pool to cool enough to allow the El Niño forcing to develop. It’s an unknown how much Nino 3.4 needs warm to overcome the WPAC warm pool. Will +1.0 be enough or do we need at least +1.5 for the El Niño circulation to dominate. Remember, we had a super El Niño +2.5 range in December 2015 and still got the WPAC forcing with the record MJO 4-6. It’s possible the WPAC forcing can hold on and prevent a canonical El Niño response and we get some type of hybrid Pacific response that the long range seasonal models will miss. So it’s possible just looking at ENSO may not tell the whole story. http://seasonal.meteo.fr/content/PS-previ-cartes?language=en