bluewave

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

Looks like the far interior sections will have a freeze this week with the record +PNA block.

Great points by @jconsoron how the WWBs and VP anomalies have been shifting west of Dateline from the long range until we get to within 10 days. So the El Niño atmospheric response keeps getting pushed back. This would keep 3.4 neutral warm to weak for a while. It could also limit 1+2 to the +2s range instead of making a move higher. Stalling out near around +2 to +3 could signal an early peak since we haven’t had any follow up EPAC WWBs since the big one back in March. The strongest east based years like 97-98 and 82-83 were able to top out over +4 for the monthly average 1+2 anomalies. https://psl.noaa.gov/enso/dashboard.html

Those ECMWF charts are 15N to 15S. We are mainly focused on closer to the equator for impacting the El Niño. Need the WWB to focus within about 5N-5S to be effective. Notice how the WWBs have been closer to the equator in the IO. But too far north near 15N to have an impact on ENSO near equator. That’s why those Euro charts look more impressive than they really are.

The WWBs are still pretty far west of 180° even with the big dip in the SOI. In years like 1997 and 2016, the WWBs were already east of 180° from March onward. So the east based warming focus should continue for the present time. Need the WWBs to shift east and the WPAC warm pool to weaken a bit for Nino 3.4 to start catching up with 1+2 and 3.

The trades still up near the Dateline is still very Niña-like despite the recent SOI drop. So the record WPAC warm pool isn’t letting the El Niño atmospheric response develop yet. These are the weakest early May WWBs for any El Niño year since 04 an 02. Nothing like the super 2016 and 1997 WWBs. This is why there is still a big lag between 3.4 and 1+2.

This is the first time I can remember seeing a subsurface chart like this. The super events in 2015 and 1997 had much more warming near and below the surface in 3.4. The warming in 1+2 can only spread out so much. Really need the trades to relax to have a shot at +1.5 strong or +2.0 super in 3.4.

Nino 1+2 didn’t get above +2 until the summer in 1972 and 3.4 was at +1.0 borderline moderate. So there have been no known El Niño evolutions with 3.4 lagging so far behind 1+2. The WPAC didn’t have the record warm pool like we have now. So this event is technically starting out more east based than any other year. How this plays out later on is still to be determined. 7th week of Nino 1+2 first going above +2 this year minus 1972.

Maybe one last freeze for some interior spots.

Nino 1+2 has been above +2 for 7 weeks and 3.4 is only +0.4. By the 7th week in 2015 of 1+2 going above +2 Nino 3.4 was +1.2. At the same point in 1997 it was +0.9. So an unusually long lag in Nino 3.4 warming with the trades staying active near the Dateline.

We could have used the upcoming record +PNA 590 DM ridge last winter.

That’s a good question. My guess the actual PDO will be contingent on how long it takes the atmosphere to have a more Nino-like response. Those PDO forecasts are a function of how the El Niño atmospheric pattern develops.

Yeah, the WPAC warm pool was warmest on record for the month of April. The trades are much stronger now near the Dateline than in 2015 and 1997. The Central Pacific is much cooler with 3.4 lagging well behind 1+2. So we don’t really have any past instances of an early El Niño evolution like this.

You are in a unique spot where you can get a top 5 warmest and snowiest in the same season due to less ice and warmer Lakes.

I know that these seasonal forecasts aren’t great. But they are forecasting the -PDO to weaken a bit in the coming months. This would be expected if some of the stronger forecasts for the El Niño worked out. Still a tough call as to how strong in 3.4 it will get since the WWBs are still pretty far west of the Dateline. This will be a learning experience on how long it takes 3.4 to warm when the current subsurface still favors 1+2 and 3. Never had 1+2 this much warmer than 3.4 in the early development phases before. 3.4 was usually closer to +1 in past years when 1+2 was over +2 for this long. So not sure what this means going forward.

Spatially using that composite as to where the departure centers lined up wasn’t bad. But the magnitude of the warm departures was way beyond. I have noticed various seasonal forecasts sometimes getting where the departures were located correct but ultimately having a cold bias. April was 7° warmer than the composite is some spots. So not sure how much a forecaster would know ahead of time to warm an older composite. Several spots had their warmest April on record. https://www.nrcc.cornell.edu/services/blog/2023/05/02/index.html

After dipping below -2 recently the more +PNA let it rise a bit. https://s2s.worldclimateservice.com/climatepanel/

I know that we both understand that. I have done the same thing. But posters on this forum hear a specific year mentioned and then aren’t happy when the snowfall or temperature forecast isn’t exactly like that year. So I had to lean more on recent year composites rather than the specifics. I guess it’s just the way people hear things and relate to their favorite winters from the past.

Tough to say when. There was a great recent paper on the topic. Gives new meaning to persistence forecast.

When you use specific analogs from an earlier era you raise expectations among your readers. It’s probably better to just draw up the maps without references to pre 2010 analogs. The only winter forecast which has been reliable since 15-16 has been some version of the SE Ridge or WAR. This feature has been present whether we had El Niño, La Niña, neutral, or uncoupled El Niño.